TY - JOUR A1 - Wolisz, Henryk A1 - Schütz, Thomas A1 - Blanke, Tobias A1 - Hagenkamp, Markus A1 - Kohrn, Markus A1 - Wesseling, Mark A1 - Müller, Dirk T1 - Cost optimal sizing of smart buildings' energy system components considering changing end-consumer electricity markets JF - Energy Y1 - 2017 U6 - https://doi.org/10.1016/j.energy.2017.06.025 VL - 137 SP - 715 EP - 728 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Bhattarai, Aroj A1 - Staat, Manfred T1 - A computational study of organ relocation after laparoscopic pectopexy to repair posthysterectomy vaginal vault prolapse JF - Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization Y1 - 2019 U6 - https://doi.org/10.1080/21681163.2019.1670095 SN - 2168-1171 PB - Taylor & Francis CY - London ER - TY - JOUR A1 - Quittmann, Oliver J. A1 - Abel, Thomas A1 - Albracht, Kirsten A1 - Meskemper, Joshua A1 - Foitschik, Tina A1 - Strüder, Heiko K. T1 - Biomechanics of handcycling propulsion in a 30-min continuous load test at lactate threshold: Kinetics, kinematics, and muscular activity in able-bodied participants JF - European Journal of Applied Physiology N2 - Purpose This study aims to investigate the biomechanics of handcycling during a continuous load trial (CLT) to assess the mechanisms underlying fatigue in upper body exercise. Methods Twelve able-bodied triathletes performed a 30-min CLT at a power output corresponding to lactate threshold in a racing recumbent handcycle mounted on a stationary ergometer. During the CLT, ratings of perceived exertion (RPE), tangential crank kinetics, 3D joint kinematics, and muscular activity of ten muscles of the upper extremity and trunk were examined using motion capturing and surface electromyography. Results During the CLT, spontaneously chosen cadence and RPE increased, whereas crank torque decreased. Rotational work was higher during the pull phase. Peripheral RPE was higher compared to central RPE. Joint range of motion decreased for elbow-flexion and radial-duction. Integrated EMG (iEMG) increased in the forearm flexors, forearm extensors, and M. deltoideus (Pars spinalis). An earlier onset of activation was found for M. deltoideus (Pars clavicularis), M. pectoralis major, M. rectus abdominis, M. biceps brachii, and the forearm flexors. Conclusion Fatigue-related alterations seem to apply analogously in handcycling and cycling. The most distal muscles are responsible for force transmission on the cranks and might thus suffer most from neuromuscular fatigue. The findings indicate that peripheral fatigue (at similar lactate values) is higher in handcycling compared to leg cycling, at least for inexperienced participants. An increase in cadence might delay peripheral fatigue by a reduced vascular occlusion. We assume that the gap between peripheral and central fatigue can be reduced by sport-specific endurance training. Y1 - 2020 U6 - https://doi.org/10.1007/s00421-020-04373-x SN - 1439-6327 IS - 120 SP - 1403 EP - 1415 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Edip, K. A1 - Sesov, V. A1 - Butenweg, Christoph A1 - Bojadjieva, J. T1 - Development of coupled numerical model for simulation of multiphase soil JF - Computers and Geotechnics N2 - In this paper, a coupled multiphase model considering both non-linearities of water retention curves and solid state modeling is proposed. The solid displacements and the pressures of both water and air phases are unknowns of the proposed model. The finite element method is used to solve the governing differential equations. The proposed method is demonstrated through simulation of seepage test and partially consolidation problem. Then, implementation of the model is done by using hypoplasticity for the solid phase and analyzing the fully saturated triaxial experiments. In integration of the constitutive law error controlling is improved and comparisons done accordingly. In this work, the advantages and limitations of the numerical model are discussed. Y1 - 2018 U6 - https://doi.org/10.1016/j.compgeo.2017.08.016 SN - 0266-352X VL - 96 SP - 118 EP - 131 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Rausch, Valentin A1 - Harbrecht, Andreas A1 - Kahmann, Stephanie Lucina A1 - Fenten, Thomas A1 - Jovanovic, Nebojsa A1 - Hackl, Michael A1 - Müller, Lars P. A1 - Staat, Manfred A1 - Wegmann, Kilian T1 - Osteosynthesis of Phalangeal Fractures: Biomechanical Comparison of Kirschner Wires, Plates, and Compression Screws JF - The Journal of Hand Surgery N2 - Purpose The aim of this study was to compare several osteosynthesis techniques (intramedullary headless compression screws, T-plates, and Kirschner wires) for distal epiphyseal fractures of proximal phalanges in a human cadaveric model. Methods A total of 90 proximal phalanges from 30 specimens (index, ring, and middle fingers) were used for this study. After stripping off all soft tissue, a transverse distal epiphyseal fracture was simulated at the proximal phalanx. The 30 specimens were randomly assigned to 1 fixation technique (30 per technique), either a 3.0-mm intramedullary headless compression screw, locking plate fixation with a 2.0-mm T-plate, or 2 oblique 1.0-mm Kirschner wires. Displacement analysis (bending, distraction, and torsion) was performed using optical tracking of an applied random speckle pattern after osteosynthesis. Biomechanical testing was performed with increasing cyclic loading and with cyclic load to failure using a biaxial torsion-tension testing machine. Results Cannulated intramedullary compression screws showed significantly less displacement at the fracture site in torsional testing. Furthermore, screws were significantly more stable in bending testing. Kirschner wires were significantly less stable than plating or screw fixation in any cyclic load to failure test setup. Conclusions Intramedullary compression screws are a highly stable alternative in the treatment of transverse distal epiphyseal phalangeal fractures. Kirschner wires seem to be inferior regarding displacement properties and primary stability. Clinical relevance Fracture fixation of phalangeal fractures using plate osteosynthesis may have the advantage of a very rigid reduction, but disadvantages such as stiffness owing to the more invasive surgical approach and soft tissue irritation should be taken into account. Headless compression screws represent a minimally invasive choice for fixation with good biomechanical properties. Y1 - 2020 U6 - https://doi.org/10.1016/j.jhsa.2020.04.010 SN - 0363-5023 VL - 45 IS - 10 SP - 987.e1 EP - 987.e8 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Dantism, Shahriar A1 - Röhlen, Desiree A1 - Dahmen, Markus A1 - Wagner, Torsten A1 - Wagner, Patrick A1 - Schöning, Michael Josef T1 - LAPS-based monitoring of metabolic responses of bacterial cultures in a paper fermentation broth JF - Sensors and Actuators B: Chemical N2 - As an alternative renewable energy source, methane production in biogas plants is gaining more and more attention. Biomass in a bioreactor contains different types of microorganisms, which should be considered in terms of process-stability control. Metabolically inactive microorganisms within the fermentation process can lead to undesirable, time-consuming and cost-intensive interventions. Hence, monitoring of the cellular metabolism of bacterial populations in a fermentation broth is crucial to improve the biogas production, operation efficiency, and sustainability. In this work, the extracellular acidification of bacteria in a paper-fermentation broth is monitored after glucose uptake, utilizing a differential light-addressable potentiometric sensor (LAPS) system. The LAPS system is loaded with three different model microorganisms (Escherichia coli, Corynebacterium glutamicum, and Lactobacillus brevis) and the effect of the fermentation broth at different process stages on the metabolism of these bacteria is studied. In this way, different signal patterns related to the metabolic response of microorganisms can be identified. By means of calibration curves after glucose uptake, the overall extracellular acidification of bacterial populations within the fermentation process can be evaluated. Y1 - 2020 U6 - https://doi.org/10.1016/j.snb.2020.128232 SN - 0925-4005 VL - 320 IS - Art. 128232 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Bayer, Robin A1 - Temiz Artmann, Aysegül A1 - Digel, Ilya A1 - Falkenstein, Julia A1 - Artmann, Gerhard A1 - Creutz, Till A1 - Hescheler, Jürgen T1 - Mechano-pharmacological testing of L-Type Ca²⁺ channel modulators via human vascular celldrum model JF - Cellular Physiology and Biochemistry N2 - Background/Aims: This study aimed to establish a precise and well-defined working model, assessing pharmaceutical effects on vascular smooth muscle cell monolayer in-vitro. It describes various analysis techniques to determine the most suitable to measure the biomechanical impact of vasoactive agents by using CellDrum technology. Methods: The so-called CellDrum technology was applied to analyse the biomechanical properties of confluent human aorta muscle cells (haSMC) in monolayer. The cell generated tensions deviations in the range of a few N/m² are evaluated by the CellDrum technology. This study focuses on the dilative and contractive effects of L-type Ca²⁺ channel agonists and antagonists, respectively. We analyzed the effects of Bay K8644, nifedipine and verapamil. Three different measurement modes were developed and applied to determine the most appropriate analysis technique for the study purpose. These three operation modes are called, particular time mode" (PTM), "long term mode" (LTM) and "real-time mode" (RTM). Results: It was possible to quantify the biomechanical response of haSMCs to the addition of vasoactive agents using CellDrum technology. Due to the supplementation of 100nM Bay K8644, the tension increased approximately 10.6% from initial tension maximum, whereas, the treatment with nifedipine and verapamil caused a significant decrease in cellular tension: 10nM nifedipine decreased the biomechanical stress around 6,5% and 50nM verapamil by 2,8%, compared to the initial tension maximum. Additionally, all tested measurement modes provide similar results while focusing on different analysis parameters. Conclusion: The CellDrum technology allows highly sensitive biomechanical stress measurements of cultured haSMC monolayers. The mechanical stress responses evoked by the application of vasoactive calcium channel modulators were quantified functionally (N/m²). All tested operation modes resulted in equal findings, whereas each mode features operation-related data analysis. Y1 - 2020 U6 - https://doi.org/10.33594/000000225 SN - 1421-9778 VL - 54 SP - 371 EP - 383 PB - Cell Physiol Biochem Press CY - Düsseldorf ER - TY - JOUR A1 - Akimbekov, Nuraly S. A1 - Digel, Ilya A1 - Abdieva, Gulzhamal A1 - Ualieva, Perizat A1 - Tastambek, Kuanysh T1 - Lignite biosolubilization and bioconversion by Bacillus sp.: the collation of analytical data JF - Biofuels N2 - The vast metabolic potential of microbes in brown coal (lignite) processing and utilization can greatly contribute to innovative approaches to sustainable production of high-value products from coal. In this study, the multi-faceted and complex coal biosolubilization process by Bacillus sp. RKB 7 isolate from the Kazakhstan coal-mining soil is reported, and the derived products are characterized. Lignite solubilization tests performed for surface and suspension cultures testify to the formation of numerous soluble lignite-derived substances. Almost 24% of crude lignite (5% w/v) was solubilized within 14 days under slightly alkaline conditions (pH 8.2). FTIR analysis revealed various functional groups in the obtained biosolubilization products. Analyses of the lignite-derived humic products by UV-Vis and fluorescence spectrometry as well as elemental analysis yielded compatible results indicating the emerging products had a lower molecular weight and degree of aromaticity. Furthermore, XRD and SEM analyses were used to evaluate the biosolubilization processes from mineralogical and microscopic points of view. The findings not only contribute to a deeper understanding of microbe–mineral interactions in coal environments, but also contribute to knowledge of coal biosolubilization and bioconversion with regard to sustainable production of humic substances. The detailed and comprehensive analyses demonstrate the huge biotechnological potential of Bacillus sp. for agricultural productivity and environmental health. KW - humic acid KW - Bacillus sp KW - lignite KW - Biosolubilization Y1 - 2021 SN - 1759-7277 VL - 12 IS - 3 SP - 247 EP - 258 PB - Taylor & Francis CY - London ER - TY - JOUR A1 - Eggert, Mathias A1 - Alberts, Jens T1 - Frontiers of business intelligence and analytics 3.0: a taxonomy-based literature review and research agenda JF - Business Research N2 - Researching the field of business intelligence and analytics (BI & A) has a long tradition within information systems research. Thereby, in each decade the rapid development of technologies opened new room for investigation. Since the early 1950s, the collection and analysis of structured data were the focus of interest, followed by unstructured data since the early 1990s. The third wave of BI & A comprises unstructured and sensor data of mobile devices. The article at hand aims at drawing a comprehensive overview of the status quo in relevant BI & A research of the current decade, focusing on the third wave of BI & A. By this means, the paper’s contribution is fourfold. First, a systematically developed taxonomy for BI & A 3.0 research, containing seven dimensions and 40 characteristics, is presented. Second, the results of a structured literature review containing 75 full research papers are analyzed by applying the developed taxonomy. The analysis provides an overview on the status quo of BI & A 3.0. Third, the results foster discussions on the predicted and observed developments in BI & A research of the past decade. Fourth, research gaps of the third wave of BI & A research are disclosed and concluded in a research agenda. Y1 - 2020 U6 - https://doi.org/10.1007/s40685-020-00108-y SN - 2198-2627 VL - 2020 IS - 13 SP - 685 EP - 739 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Smith, Wayne A1 - Kotliar, Konstantin A1 - Lammertyn, Leandi A1 - Ramoshaba, Nthai E. A1 - Vilser, Walthard A1 - Huisman, Hugo W. A1 - Schutte, Aletta E. T1 - Retinal vessel caliber and caliber responses in true normotensive black and white adults: The African-PREDICT study JF - Microvascular Research N2 - Purpose Globally, a detrimental shift in cardiovascular disease risk factors and a higher mortality level are reported in some black populations. The retinal microvasculature provides early insight into the pathogenesis of systemic vascular diseases, but it is unclear whether retinal vessel calibers and acute retinal vessel functional responses differ between young healthy black and white adults. Methods We included 112 black and 143 white healthy normotensive adults (20–30 years). Retinal vessel calibers (central retinal artery and vein equivalent (CRAE and CRVE)) were calculated from retinal images and vessel caliber responses to flicker light induced provocation (FLIP) were determined. Additionally, ambulatory blood pressure (BP), anthropometry and blood samples were collected. Results The groups displayed similar 24 h BP profiles and anthropometry (all p > .24). Black participants demonstrated a smaller CRAE (158 ± 11 vs. 164 ± 11 MU, p < .001) compared to the white group, whereas CRVE was similar (p = .57). In response to FLIP, artery maximal dilation was greater in the black vs. white group (5.6 ± 2.1 vs. 3.3 ± 1.8%; p < .001). Conclusions Already at a young age, healthy black adults showed narrower retinal arteries relative to the white population. Follow-up studies are underway to show if this will be related to increased risk for hypertension development. The reason for the larger vessel dilation responses to FLIP in the black population is unclear and warrants further investigation. Y1 - 2020 U6 - https://doi.org/10.1016/j.mvr.2019.103937 SN - 0026-2862 VL - 128 IS - Article 103937 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Valero, D. A1 - Bung, Daniel Bernhard A1 - Crookston, B. M. T1 - Closure to “Energy Dissipation of a Type III Basin under Design and Adverse Conditions for Stepped and Smooth Spillways” JF - Journal of Hydraulic Engineering Y1 - 2019 U6 - https://doi.org/10.1061/(ASCE)HY.1943-7900.0001669 VL - 146 IS - 2 PB - ASCE CY - Reston, Va. ER - TY - JOUR A1 - Streese, Lukas A1 - Kotliar, Konstantin A1 - Deiseroth, Arne A1 - Infanger, Denis A1 - Gugleta, Konstantin A1 - Schmaderer, Christoph A1 - Hanssen, Henner T1 - Retinal endothelial function in cardiovascular risk patients: A randomized controlled exercise trial JF - Scandinavian Journal of Medicine and Science in Sports N2 - The aim of this study was to investigate, for the first time, the effects of high-intensity interval training (HIIT) on retinal microvascular endothelial function in cardiovascular (CV) risk patients. In the randomized controlled trial, middle-aged and previously sedentary patients with increased CV risk (aged 58 ± 6 years) with ≥ two CV risk factors were randomized into a 12-week HIIT (n = 33) or control group (CG, n = 36) with standard physical activity recommendations. A blinded examiner measured retinal endothelial function by flicker light-induced maximal arteriolar (ADmax) and venular (VDmax) dilatation as well as the area under the arteriolar (AFarea) and venular (VFarea) flicker curve using a retinal vessel analyzer. Standardized assessments of CV risk factors, cardiorespiratory fitness, and retinal endothelial function were performed before and after HIIT. HIIT reduced body mass index, fat mass, and low-density lipoprotein and increased muscle mass and peak oxygen uptake (VO2peak). Both ADmax (pre: 2.7 ± 2.1%, post: 3.0 ± 2.2%, P = .018) and AFarea (pre: 32.6 ± 28.4%*s, post: 37.7 ± 30.6%*s, P = .016) increased after HIIT compared with CG (ADmax, pre: 3.2 ± 1.8%, post: 2.9 ± 1.8%, P = .254; AFarea, pre: 41.6 ± 28.5%*s, post: 37.8 ± 27.0%*s, P = .186). Venular function remained unchanged after HIIT. There was a significant association between ∆-change VO2peak and ∆-changes ADmax and AFarea (P = .026, R² = 0.073; P = .019, R² = 0.081, respectively). 12-weeks of HIIT improved retinal endothelial function in middle-aged patients with increased CV risk independent of the reduction in classical CV risk factors. Exercise has the potential to reverse or at least postpone progression of small vessel disease in older adults with increased CV risk under standard medication. Dynamic retinal vessel analysis seems to be a sensitive tool to detect treatment effects of exercise interventions on retinal microvascular endothelial function in middle-aged individuals with increased CV risk. Y1 - 2020 U6 - https://doi.org/10.1111/sms.13560 SN - 1600-0838 VL - 30 IS - 2 SP - 272 EP - 280 PB - Wiley CY - Oxford ER - TY - JOUR A1 - Schmidt, Aaron C. A1 - Turgut, Hatice A1 - Le, Dao A1 - Beloqui, Ana A1 - Delaittre, Guillaume T1 - Making the best of it: nitroxide-mediated polymerization of methacrylates via the copolymerization approach with functional styrenics JF - Polymer Chemistry N2 - The SG1-mediated solution polymerization of methyl methacrylate (MMA) and oligo(ethylene glycol) methacrylate (OEGMA, Mₙ = 300 g mol⁻¹) in the presence of a small amount of functional/reactive styrenic comonomer is investigated. Moieties such as pentafluorophenyl ester, triphenylphosphine, azide, pentafluorophenyl, halide, and pyridine are considered. A comonomer fraction as low as 5 mol% typically results in a controlled/living behavior, at least up to 50% conversion. Chain extensions with styrene for both systems were successfully performed. Variation of physical properties such as refractive index (for MMA) and phase transition temperature (for OEGMA) were evaluated by comparing to 100% pure homopolymers. The introduction of an activated ester styrene derivative in the polymerization of OEGMA allows for the synthesis of reactive and hydrophilic polymer brushes with defined thickness. Finally, using the example of pentafluorostyrene as controlling comonomer, it is demonstrated that functional PMMA-b-PS are able to maintain a phase separation ability, as evidenced by the formation of nanostructured thin films. Y1 - 2020 U6 - https://doi.org/10.1039/C9PY01458F VL - 11 IS - 2 SP - 593 EP - 604 PB - Royal Society of Chemistry (RSC) CY - Cambridge ER - TY - JOUR A1 - Hamou, Hussam Aldin A1 - Kotliar, Konstantin A1 - Tan, Sonny Kian A1 - Weiß, Christel A1 - Blume, Christian A1 - Clusmann, Hans A1 - Schubert, Gerrit Alexander A1 - Albanna, Walid T1 - Surgical nuances and placement of subgaleal drains for supratentorial procedures—a prospective analysis of efficacy and outcome in 150 craniotomies JF - Acta Neurochirurgica N2 - Background For supratentorial craniotomy, surgical access, and closure technique, including placement of subgaleal drains, may vary considerably. The influence of surgical nuances on postoperative complications such as cerebrospinal fluid leakage or impaired wound healing overall remains largely unclear. With this study, we are reporting our experiences and the impact of our clinical routines on outcome in a prospectively collected data set. Method We prospectively observed 150 consecutive patients undergoing supratentorial craniotomy and recorded technical variables (type/length of incision, size of craniotomy, technique of dural and skin closure, type of dressing, and placement of subgaleal drains). Outcome variables (subgaleal hematoma/CSF collection, periorbital edema, impairment of wound healing, infection, and need for operative revision) were recorded at time of discharge and at late follow-up. Results Early subgaleal fluid collection was observed in 36.7% (2.8% at the late follow-up), and impaired wound healing was recorded in 3.3% of all cases, with an overall need for operative revision of 6.7%. Neither usage of dural sealants, lack of watertight dural closure, and presence of subgaleal drains, nor type of skin closure or dressing influenced outcome. Curved incisions, larger craniotomy, and tumor size, however, were associated with an increase in early CSF or hematoma collection (p < 0.0001, p = 0.001, p < 0.01 resp.), and larger craniotomy size was associated with longer persistence of subgaleal fluid collections (p < 0.05). Conclusions Based on our setting, individual surgical nuances such as the type of dural closure and the use of subgaleal drains resulted in a comparable complication rate and outcome. Subgaleal fluid collections were frequently observed after supratentorial procedures, irrespective of the closing technique employed, and resolve spontaneously in the majority of cases without significant sequelae. Our results are limited due to the observational nature in our single-center study and need to be validated by supportive prospective randomized design. Y1 - 2020 U6 - https://doi.org/10.1007/s00701-019-04196-6 SN - 0942-0940 VL - 2020 IS - 162 SP - 729 EP - 736 PB - Springer Nature CY - Cham ER - TY - JOUR A1 - Roeth, A.A. A1 - Slabu, I. A1 - Kessler, A. A1 - Engelmann, Ulrich M. T1 - Local treatment of pancreatic cancer with magnetic nanoparticles JF - HPB Y1 - 2019 U6 - https://doi.org/10.1016/j.hpb.2019.10.959 SN - 1365-182X VL - 21 IS - Supplement 3 SP - S868 EP - S869 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Digel, Ilya A1 - Kern, Inna A1 - Geenen, Eva-Maria A1 - Akimbekov, Nuraly S. T1 - Dental plaque removal by ultrasonic toothbrushes JF - dentistry journal N2 - With the variety of toothbrushes on the market, the question arises, which toothbrush is best suited to maintain oral health? This thematic review focuses first on plaque formation mechanisms and then on the plaque removal effectiveness of ultrasonic toothbrushes and their potential in preventing oral diseases like periodontitis, gingivitis, and caries. We overviewed the physical effects that occurred during brushing and tried to address the question of whether ultrasonic toothbrushes effectively reduced the microbial burden by increasing the hydrodynamic forces. The results of published studies show that electric toothbrushes, which combine ultrasonic and sonic (or acoustic and mechanic) actions, may have the most promising effect on good oral health. Existing ultrasonic/sonic toothbrush models do not significantly differ regarding the removal of dental biofilm and the reduction of gingival inflammation compared with other electrically powered toothbrushes, whereas the manual toothbrushes show a lower effectiveness. Y1 - 2020 U6 - https://doi.org/10.3390/dj8010028 SN - 2304-6767 VL - 8 IS - 28 SP - 1 EP - 13 PB - MDPI CY - Basel ER - TY - JOUR A1 - Muschallik, Lukas A1 - Molinnus, Denise A1 - Jablonski, Melanie A1 - Kipp, Carina Ronja A1 - Bongaerts, Johannes A1 - Pohl, Martina A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Selmer, Thorsten A1 - Siegert, Petra T1 - Synthesis of α-hydroxy ketones and vicinal (R, R)-diols by Bacillus clausii DSM 8716ᵀ butanediol dehydrogenase JF - RSC Advances N2 - α-hydroxy ketones (HK) and 1,2-diols are important building blocks for fine chemical synthesis. Here, we describe the R-selective 2,3-butanediol dehydrogenase from B. clausii DSM 8716ᵀ (BcBDH) that belongs to the metal-dependent medium chain dehydrogenases/reductases family (MDR) and catalyzes the selective asymmetric reduction of prochiral 1,2-diketones to the corresponding HK and, in some cases, the reduction of the same to the corresponding 1,2-diols. Aliphatic diketones, like 2,3-pentanedione, 2,3-hexanedione, 5-methyl-2,3-hexanedione, 3,4-hexanedione and 2,3-heptanedione are well transformed. In addition, surprisingly alkyl phenyl dicarbonyls, like 2-hydroxy-1-phenylpropan-1-one and phenylglyoxal are accepted, whereas their derivatives with two phenyl groups are not substrates. Supplementation of Mn²⁺ (1 mM) increases BcBDH's activity in biotransformations. Furthermore, the biocatalytic reduction of 5-methyl-2,3-hexanedione to mainly 5-methyl-3-hydroxy-2-hexanone with only small amounts of 5-methyl-2-hydroxy-3-hexanone within an enzyme membrane reactor is demonstrated. Y1 - 2020 U6 - https://doi.org/10.1039/D0RA02066D SN - 2046-2069 VL - 10 SP - 12206 EP - 12216 PB - Royal Society of Chemistry (RSC) CY - Cambridge ER - TY - JOUR A1 - Welden, Rene A1 - Schöning, Michael Josef A1 - Wagner, Patrick H. A1 - Wagner, Torsten T1 - Light-Addressable Electrodes for Dynamic and Flexible Addressing of Biological Systems and Electrochemical Reactions JF - Sensors N2 - In this review article, we are going to present an overview on possible applications of light-addressable electrodes (LAE) as actuator/manipulation devices besides classical electrode structures. For LAEs, the electrode material consists of a semiconductor. Illumination with a light source with the appropiate wavelength leads to the generation of electron-hole pairs which can be utilized for further photoelectrochemical reaction. Due to recent progress in light-projection technologies, highly dynamic and flexible illumination patterns can be generated, opening new possibilities for light-addressable electrodes. A short introduction on semiconductor–electrolyte interfaces with light stimulation is given together with electrode-design approaches. Towards applications, the stimulation of cells with different electrode materials and fabrication designs is explained, followed by analyte-manipulation strategies and spatially resolved photoelectrochemical deposition of different material types. Y1 - 2020 U6 - https://doi.org/10.3390/s20061680 SN - 1424-8220 VL - 20 IS - 6 PB - MDPI CY - Basel ER - TY - JOUR A1 - Kerres, Karsten A1 - Gredigk-Hoffmann, Sylvia A1 - Jathe, Rüdiger A1 - Orlik, Stefan A1 - Sariyildiz, Mustafa A1 - Schmidt, Torsten A1 - Sympher, Klaus-Jochen A1 - Uhlenbroch, Adrian T1 - Future approaches for sewer system condition assessment JF - Water Practice & Technology N2 - Different analytical approaches exist to describe the structural substance or wear reserve of sewer systems. The aim is to convert engineering assessments of often complex defect patterns into computational algorithms and determine a substance class for a sewer section or manhole. This analytically determined information is essential for strategic rehabilitation planning processes up to network level, as it corresponds to the most appropriate rehabilitation type and can thus provide decision-making support. Current calculation methods differ clearly from each other in parts, so that substance classes determined by the different approaches are only partially comparable with each other. The objective of the German R&D cooperation project ‘SubKanS’ is to develop a methodology for classifying the specific defect patterns resulting from the interaction of all the individual defects, and their severities and locations. The methodology takes into account the structural substance of sewer sections and manholes, based on real data and theoretical considerations analogous to the condition classification of individual defects. The result is a catalogue of defect patterns and characteristics, as well as associated structural substance classifications of sewer systems (substance classes). The methodology for sewer system substance classification is developed so that the classification of individual defects can be transferred into a substance class of the sewer section or manhole, eventually taking into account further information (e.g. pipe material, nominal diameter, etc.). The result is a validated methodology for automated sewer system substance classification. Y1 - 2020 U6 - https://doi.org/10.2166/wpt.2020.027 SN - 1751-231X IS - 15 (2) SP - 386 EP - 393 PB - IWA Publishing CY - London ER - TY - JOUR A1 - Köhler, Klemens T1 - A conflict theory perspective of IT attacks – consequences for IT security education N2 - Cyberspace is "the environment formed by physical and non-physical components to store, modify, and exchange data using computer networks" (NATO CCDCOE). Beyond that, it is an environment where people interact. IT attacks are hostile, non-cooperative interactions that can be described with conflict theory. Applying conflict theory to IT security leads to different objectives for end-user education, requiring different formats like agency-based competence developing games. Y1 - 2020 IS - Preprint ER - TY - JOUR A1 - Finger, Felix A1 - Braun, Carsten A1 - Bil, Cees T1 - Impact of Battery Performance on the Initial Sizing of Hybrid-Electric General Aviation Aircraft JF - Journal of Aerospace Engineering N2 - Studies suggest that hybrid-electric aircraft have the potential to generate fewer emissions and be inherently quieter when compared to conventional aircraft. By operating combustion engines together with an electric propulsion system, synergistic benefits can be obtained. However, the performance of hybrid-electric aircraft is still constrained by a battery’s energy density and discharge rate. In this paper, the influence of battery performance on the gross mass for a four-seat general aviation aircraft with a hybrid-electric propulsion system is analyzed. For this design study, a high-level approach is chosen, using an innovative initial sizing methodology to determine the minimum required aircraft mass for a specific set of requirements and constraints. Only the peak-load shaving operational strategy is analyzed. Both parallel- and serial-hybrid propulsion configurations are considered for two different missions. The specific energy of the battery pack is varied from 200 to 1,000 W⋅h/kg, while the discharge time, and thus the normalized discharge rating (C-rating), is varied between 30 min (2C discharge rate) and 2 min (30C discharge rate). With the peak-load shaving operating strategy, it is desirable for hybrid-electric aircraft to use a light, low capacity battery system to boost performance. For this case, the battery’s specific power rating proved to be of much higher importance than for full electric designs, which have high capacity batteries. Discharge ratings of 20C allow a significant take-off mass reduction aircraft. The design point moves to higher wing loadings and higher levels of hybridization if batteries with advanced technology are used. Y1 - 2020 U6 - https://doi.org/10.1061/(ASCE)AS.1943-5525.0001113 SN - 1943-5525 VL - 33 IS - 3 PB - ASCE CY - Reston, Va. ER - TY - JOUR A1 - Jildeh, Zaid B. A1 - Kirchner, Patrick A1 - Oberländer, Jan A1 - Vahidpour, Farnoosh A1 - Wagner, Patrick H. A1 - Schöning, Michael Josef T1 - Development of a package-sterilization process for aseptic filling machines: A numerical approach and validation for surface treatment with hydrogen peroxide JF - Sensor and Actuators A: Physical N2 - Within the present work a sterilization process by a heated gas mixture that contains hydrogen peroxide (H₂O₂) is validated by experiments and numerical modeling techniques. The operational parameters that affect the sterilization efficacy are described alongside the two modes of sterilization: gaseous and condensed H₂O₂. Measurements with a previously developed H₂O₂ gas sensor are carried out to validate the applied H₂O₂ gas concentration during sterilization. We performed microbiological tests at different H₂O₂ gas concentrations by applying an end-point method to carrier strips, which contain different inoculation loads of Geobacillus stearothermophilus spores. The analysis of the sterilization process of a pharmaceutical glass vial is performed by numerical modeling. The numerical model combines heat- and advection-diffusion mass transfer with vapor–pressure equations to predict the location of condensate formation and the concentration of H₂O₂ at the packaging surfaces by changing the gas temperature. For a sterilization process of 0.7 s, a H₂O₂ gas concentration above 4% v/v is required to reach a log-count reduction above six. The numerical results showed the location of H₂O₂ condensate formation, which decreases with increasing sterilant-gas temperature. The model can be transferred to different gas nozzle- and packaging geometries to assure the absence of H₂O₂ residues. Y1 - 2020 U6 - https://doi.org/10.1016/j.sna.2019.111691 SN - 0924-4247 VL - 303 IS - 111691 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Rausch, Valentin A1 - Kahmann, Stephanie Lucina A1 - Baltschun, Christoph A1 - Staat, Manfred A1 - Müller, Lars P. A1 - Wegmann, Kilian T1 - Pressure distribution to the distal biceps tendon at the radial tuberosity: a biomechanical study JF - The Journal of Hand Surgery N2 - Purpose Mechanical impingement at the narrow radioulnar space of the tuberosity is believed to be an etiological factor in the injury of the distal biceps tendon. The aim of the study was to compare the pressure distribution at the proximal radioulnar space between 2 fixation techniques and the intact state. Methods Six right arms and 6 left arms from 5 female and 6 male frozen specimens were used for this study. A pressure transducer was introduced at the height of the radial tuberosity with the intact distal biceps tendon and after 2 fixation methods: the suture-anchor and the cortical button technique. The force (N), maximum pressure (kPa) applied to the radial tuberosity, and the contact area (mm²) of the radial tuberosity with the ulna were measured and differences from the intact tendon were detected from 60° supination to 60° pronation in 15° increments with the elbow in full extension and in 45° and 90° flexion of the elbow. Results With the distal biceps tendon intact, the pressures during pronation were similar regardless of extension and flexion and were the highest at 60° pronation with 90° elbow flexion (23.3 ± 53.5 kPa). After repair of the tendon, the mean peak pressure, contact area, and total force showed an increase regardless of the fixation technique. Highest peak pressures were found using the cortical button technique at 45° flexion of the elbow and 60° pronation. These differences were significantly different from the intact tendon. The contact area was significantly larger in full extension and 15°, 30°, and 60° pronation using the cortical button technique. Conclusions Pressures on the distal biceps tendon at the radial tuberosity increase during pronation, especially after repair of the tendon. Clinical relevance Mechanical impingement could play a role in both the etiology of primary distal biceps tendon ruptures and the complications occurring after fixation of the tendon using certain techniques. Y1 - 2020 U6 - https://doi.org/10.1016/j.jhsa.2020.01.006 SN - 0363-5023 VL - 45 IS - 8 SP - 776.e1 EP - 776.e9 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Attar, Mandana Hossein Zadeh A1 - Merk, Hans F. A1 - Kotliar, Konstantin A1 - Wurpts, Gerda A1 - Röseler, Stefani A1 - Moll-Slodowy, Silke A1 - Plange, Johann A1 - Baron, Jens Malte A1 - Balakirski, Galina T1 - The CD63 basophil activation test as a diagnostic tool for assessing autoimmunity in patients with chronic spontaneous urticaria JF - European Journal of Dermatology Y1 - 2019 U6 - https://doi.org/10.1684/ejd.2019.3680 VL - 29 IS - 6 SP - 614 EP - 618 ER - TY - JOUR A1 - Cosma, Cosmin A1 - Kessler, Julia A1 - Gebhardt, Andreas A1 - Campbell, Ian A1 - Balc, Nicolae T1 - Improving the Mechanical Strength of Dental Applications and Lattice Structures SLM Processed JF - Materials N2 - To manufacture custom medical parts or scaffolds with reduced defects and high mechanical characteristics, new research on optimizing the selective laser melting (SLM) parameters are needed. In this work, a biocompatible powder, 316L stainless steel, is characterized to understand the particle size, distribution, shape and flowability. Examination revealed that the 316L particles are smooth, nearly spherical, their mean diameter is 39.09 μm and just 10% of them hold a diameter less than 21.18 μm. SLM parameters under consideration include laser power up to 200 W, 250–1500 mm/s scanning speed, 80 μm hatch spacing, 35 μm layer thickness and a preheated platform. The effect of these on processability is evaluated. More than 100 samples are SLM-manufactured with different process parameters. The tensile results show that is possible to raise the ultimate tensile strength up to 840 MPa, adapting the SLM parameters for a stable processability, avoiding the technological defects caused by residual stress. Correlating with other recent studies on SLM technology, the tensile strength is 20% improved. To validate the SLM parameters and conditions established, complex bioengineering applications such as dental bridges and macro-porous grafts are SLM-processed, demonstrating the potential to manufacture medical products with increased mechanical resistance made of 316L. Y1 - 2020 U6 - https://doi.org/10.3390/ma13040905 SN - 1996-1944 VL - 13 IS - 4 SP - 1 EP - 18 PB - MDPI CY - Basel ER - TY - JOUR A1 - Rupp, Matthias A1 - Rieke, Christian A1 - Handschuh, Nils A1 - Kuperjans, Isabel T1 - Economic and ecological optimization of electric bus charging considering variable electricity prices and CO₂eq intensities JF - Transportation Research Part D: Transport and Environment N2 - In many cities, diesel buses are being replaced by electric buses with the aim of reducing local emissions and thus improving air quality. The protection of the environment and the health of the population is the highest priority of our society. For the transport companies that operate these buses, not only ecological issues but also economic issues are of great importance. Due to the high purchase costs of electric buses compared to conventional buses, operators are forced to use electric vehicles in a targeted manner in order to ensure amortization over the service life of the vehicles. A compromise between ecology and economy must be found in order to both protect the environment and ensure economical operation of the buses. In this study, we present a new methodology for optimizing the vehicles’ charging time as a function of the parameters CO₂eq emissions and electricity costs. Based on recorded driving profiles in daily bus operation, the energy demands of conventional and electric buses are calculated for the passenger transportation in the city of Aachen in 2017. Different charging scenarios are defined to analyze the influence of the temporal variability of CO₂eq intensity and electricity price on the environmental impact and economy of the bus. For every individual day of a year, charging periods with the lowest and highest costs and emissions are identified and recommendations for daily bus operation are made. To enable both the ecological and economical operation of the bus, the parameters of electricity price and CO₂ are weighted differently, and several charging periods are proposed, taking into account the priorities previously set. A sensitivity analysis is carried out to evaluate the influence of selected parameters and to derive recommendations for improving the ecological and economic balance of the battery-powered electric vehicle. In all scenarios, the optimization of the charging period results in energy cost savings of a maximum of 13.6% compared to charging at a fixed electricity price. The savings potential of CO₂eq emissions is similar, at 14.9%. From an economic point of view, charging between 2 a.m. and 4 a.m. results in the lowest energy costs on average. The CO₂eq intensity is also low in this period, but midday charging leads to the largest savings in CO₂eq emissions. From a life cycle perspective, the electric bus is not economically competitive with the conventional bus. However, from an ecological point of view, the electric bus saves on average 37.5% CO₂eq emissions over its service life compared to the diesel bus. The reduction potential is maximized if the electric vehicle exclusively consumes electricity from solar and wind power. Y1 - 2020 U6 - https://doi.org/10.1016/j.trd.2020.102293 SN - 1361-9209 VL - 81 IS - Article 102293 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Pietsch, Wolfram T1 - Augmenting voice of the customer analysis by analysis of belief JF - QFD-Forum Y1 - 2015 SN - 1431-6951 IS - 30 SP - 1 EP - 5 ER - TY - JOUR A1 - Mennicken, Max A1 - Peter, Sophia K. A1 - Kaulen, Corinna A1 - Simon, Ulrich A1 - Karthäuser, Silvia T1 - Transport through Redox-Active Ru-Terpyridine Complexes Integrated in Single Nanoparticle Devices JF - The Journal of Physical Chemistry C N2 - Transition metal complexes are electrofunctional molecules due to their high conductivity and their intrinsic switching ability involving a metal-to-ligand charge transfer. Here, a method is presented to contact reliably a few to single redox-active Ru-terpyridine complexes in a CMOS compatible nanodevice and preserve their electrical functionality. Using hybrid materials from 14 nm gold nanoparticles (AuNP) and bis-{4′-[4-(mercaptophenyl)-2,2′:6′,2″-terpyridine]}-ruthenium(II) complexes a device size of 30² nm² inclusive nanoelectrodes is achieved. Moreover, this method bears the opportunity for further downscaling. The Ru-complex AuNP devices show symmetric and asymmetric current versus voltage curves with a hysteretic characteristic in two well separated conductance ranges. By theoretical approximations based on the single-channel Landauer model, the charge transport through the formed double-barrier tunnel junction is thoroughly analyzed and its sensibility to the molecule/metal contact is revealed. It can be verified that tunneling transport through the HOMO is the main transport mechanism while decoherent hopping transport is present to a minor extent. Y1 - 2020 U6 - https://doi.org/10.1021/acs.jpcc.9b11716 SN - 1932-7455 VL - 124 IS - 8 SP - 4881 EP - 4889 PB - ACS Publications CY - Washington, DC ER - TY - JOUR A1 - Köhler, Klemens A1 - Röpke, René A1 - Wolf, Martin T1 - Through a mirror darkly – On the obscurity of teaching goals in game-based learning in IT security JF - ISAGA 2019: Simulation Gaming Through Times and Disciplines N2 - Teachers and instructors use very specific language communicating teaching goals. The most widely used frameworks of common reference are the Bloom’s Taxonomy and the Revised Bloom’s Taxonomy. The latter provides distinction of 209 different teaching goals which are connected to methods. In Competence Developing Games (CDGs - serious games to convey knowledge) and in IT security education, a two- or three level typology exists, reducing possible learning outcomes to awareness, training, and education. This study explores whether this much simpler framework succeeds in achieving the same range of learning outcomes. Method wise a keyword analysis was conducted. The results were threefold: 1. The words used to describe teaching goals in CDGs on IT security education do not reflect the whole range of learning outcomes. 2. The word choice is nevertheless different from common language, indicating an intentional use of language. 3. IT security CDGs use different sets of terms to describe learning outcomes, depending on whether they are awareness, training, or education games. The interpretation of the findings is that the reduction to just three types of CDGs reduces the capacity to communicate and think about learning outcomes and consequently reduces the outcomes that are intentionally achieved. KW - IT security education KW - Competence Developing Games KW - Game-based learning KW - Keyword analysis KW - Bloom’s Taxonomy Y1 - 2021 U6 - https://doi.org/10.1007/978-3-030-72132-9_6 N1 - ISAGA 2019 - International Simulation and Gaming Association Conference. 26-30 August 2019. Warsaw, Poland. Part of the Lecture Notes in Computer Science book series (LNCS, volume 11988) SP - 61 EP - 73 PB - Springer CY - Cham ER - TY - JOUR A1 - Pilas, Johanna A1 - Selmer, Thorsten A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Screen-printed carbon electrodes modified with graphene oxide for the design of a reagent-free NAD+-dependent biosensor array JF - Analytical Chemistry Y1 - 2019 U6 - https://doi.org/10.1021/acs.analchem.9b04481 VL - 91 IS - 23 SP - 15293 EP - 15299 PB - ACS Publications CY - Washington ER - TY - JOUR A1 - Capitain, Charlotte A1 - Ross-Jones, Jesse A1 - Möhring, Sophie A1 - Tippkötter, Nils T1 - Differential scanning calorimetry for quantification of polymer biodegradability in compost JF - International Biodeterioration & Biodegradation N2 - The objective of this study is the establishment of a differential scanning calorimetry (DSC) based method for online analysis of the biodegradation of polymers in complex environments. Structural changes during biodegradation, such as an increase in brittleness or crystallinity, can be detected by carefully observing characteristic changes in DSC profiles. Until now, DSC profiles have not been used to draw quantitative conclusions about biodegradation. A new method is presented for quantifying the biodegradation using DSC data, whereby the results were validated using two reference methods. The proposed method is applied to evaluate the biodegradation of three polymeric biomaterials: polyhydroxybutyrate (PHB), cellulose acetate (CA) and Organosolv lignin. The method is suitable for the precise quantification of the biodegradability of PHB. For CA and lignin, conclusions regarding their biodegradation can be drawn with lower resolutions. The proposed method is also able to quantify the biodegradation of blends or composite materials, which differentiates it from commonly used degradation detection methods. Y1 - 2020 U6 - https://doi.org/10.1016/j.ibiod.2020.104914 SN - 0964-8305 VL - 149 SP - In Press, Article number 104914 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Göddeke, Dominik A1 - Strzodka, Robert A1 - Mohd-Yusof, Jamaludin A1 - McCormick, Patrick A1 - Buijssen, Sven H.M. A1 - Grajewski, Matthias A1 - Turek, Stefan T1 - Exploring weak scalability for FEM calculations on a GPU-enhanced cluster JF - Parallel Computing Y1 - 2007 U6 - https://doi.org/10.1016/j.parco.2007.09.002 SN - 0167-8191 VL - 33 IS - 10-11 SP - 685 EP - 699 ER - TY - JOUR A1 - Grajewski, Matthias A1 - Köster, Michael A1 - Turek, Stefan T1 - Mathematical and Numerical Analysis of a Robust and Efficient Grid Deformation Method in the Finite Element Context JF - SIAM Journal on Scientific Computing Y1 - 2009 U6 - https://doi.org/10.1137/050639387 VL - 31 IS - 2 SP - 1539 EP - 1557 PB - Society for Industrial and Applied Mathematics CY - Philadelphia, Pa. ER - TY - JOUR A1 - Grajewski, Matthias A1 - Köster, Michael A1 - Turek, Stefam T1 - Numerical analysis and implementational aspects of a new multilevel grid deformation method JF - Applied Numerical Mathematics N2 - Recently, we introduced and mathematically analysed a new method for grid deformation (Grajewski et al., 2009) [15] we call basic deformation method (BDM) here. It generalises the method proposed by Liao et al. (Bochev et al., 1996; Cai et al., 2004; Liao and Anderson, 1992) [4], [6], [20]. In this article, we employ the BDM as core of a new multilevel deformation method (MDM) which leads to vast improvements regarding robustness, accuracy and speed. We achieve this by splitting up the deformation process in a sequence of easier subproblems and by exploiting grid hierarchy. Being of optimal asymptotic complexity, we experience speed-ups up to a factor of 15 in our test cases compared to the BDM. This gives our MDM the potential for tackling large grids and time-dependent problems, where possibly the grid must be dynamically deformed once per time step according to the user's needs. Moreover, we elaborate on implementational aspects, in particular efficient grid searching, which is a key ingredient of the BDM. Y1 - 2010 U6 - https://doi.org/10.1016/j.apnum.2010.03.017 SN - 0168-9274 VL - 60 IS - 8 SP - 767 EP - 781 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Grajewski, Matthias A1 - Hron, Jaroslav A1 - Turek, Stefan T1 - Numerical analysis for a new non-conforming linear finite element on quadrilaterals JF - Journal of Computational and Applied Mathematics Y1 - 2006 U6 - https://doi.org/10.1016/j.cam.2005.05.024 SN - 0377-0427 VL - 193 IS - 1 SP - 38 EP - 50 ER - TY - JOUR A1 - Grajewski, Matthias A1 - Hron, Jaroslav A1 - Turek, Stefan T1 - Dual weighted a posteriori error estimation for a new nonconforming linear finite element on quadrilaterals JF - Applied Numerical Mathematics N2 - After a short introduction of a new nonconforming linear finite element on quadrilaterals recently developed by Park, we derive a dual weighted residual-based a posteriori error estimator (in the sense of Becker and Rannacher) for this finite element. By computing a corresponding dual solution we estimate the error with respect to a given target error functional. The reliability and efficiency of this estimator is analyzed in several numerical experiments. Y1 - 2005 U6 - https://doi.org/10.1016/j.apnum.2004.09.016 SN - 0168-9274 VL - 54 IS - 3-4 SP - 504 EP - 518 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Knox, Ronald A1 - Bruggemann, Andrea A1 - Gossmann, Matthias A1 - Thomas, Ulrich A1 - Horváth, András A1 - Dragicevic, Elena A1 - Stoelzle-Feix, Sonja A1 - Fertig, Niels A1 - Jung, Alexander A1 - Raman, Aravind Hariharan A1 - Staat, Manfred A1 - Linder, Peter T1 - Combining physiological relevance and throughput for in vitro cardiac contractility measurement JF - Biophysical Journal N2 - Despite increasing acceptance of human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in safety pharmacology, controversy remains about the physiological relevance of existing in vitro models for their mechanical testing. We hypothesize that existing signs of immaturity of the cell models result from an improper mechanical environment. We cultured hiPSC-CMs in a 96-well format on hyperelastic silicone membranes imitating their native mechanical environment, resulting in physiological responses to compound stimuli.We validated cell responses on the FLEXcyte 96, with a set of reference compounds covering a broad range of cellular targets, including ion channel modulators, adrenergic receptor modulators and kinase inhibitors. Acute (10 - 30 min) and chronic (up to 7 days) effects were investigated. Furthermore, the measurements were complemented with electromechanical models based on electrophysiological recordings of the used cell types.hiPSC-CMs were cultured on freely-swinging, ultra-thin and hyperelastic silicone membranes. The weight of the cell culture medium deflects the membranes downwards. Rhythmic contraction of the hiPSC-CMs resulted in dynamic deflection changes which were quantified by capacitive distance sensing. The cells were cultured for 7 days prior to compound addition. Acute measurements were conducted 10-30 minutes after compound addition in standard culture medium. For chronic treatment, compound-containing medium was replaced daily for up to 7 days. Electrophysiological properties of the employed cell types were recorded by automated patch-clamp (Patchliner) and the results were integrated into the electromechanical model of the system.Calcium channel agonist S Bay K8644 and beta-adrenergic stimulator isoproterenol induced significant positive inotropic responses without additional external stimulation. Kinase inhibitors displayed cardiotoxic effects on a functional level at low concentrations. The system-integrated analysis detected alterations in beating shape as well as frequency and arrhythmic events and we provide a quantitative measure of these. Y1 - 2020 U6 - https://doi.org/10.1016/j.bpj.2019.11.3104 SN - 0006-3495 N1 - Raman, Arayind Hariharan im Artikel unter dem Namen: Raman, Alexander H. VL - 118 IS - Issue 3, Supplement 1 SP - 570a PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Vögele, Stefan A1 - Grajewski, Matthias A1 - Govorukha, Kristina A1 - Rübbelke, Dirk T1 - Challenges for the European steel industry: Analysis, possible consequences and impacts on sustainable development JF - Applied Energy N2 - The steel industry in the European Union (EU), important for the economy as a whole, faces various challenges. These are inter alia volatile prices for relevant input factors, uncertainties concerning the regulation of CO₂-emissions and market shocks caused by the recently introduced additional import duties in the US, which is an important sales market. We examine primary and secondary effects of these challenges on the steel industry in the EU and their impacts on European and global level. Developing and using a suitable meta-model, we analyze the competitiveness of key steel producing countries with respect to floor prices depending on selected cost factors and draw conclusions on the impacts in the trade of steel on emissions, energy demand, on the involvement of developing countries in the value chain as well on the need for innovations to avoid relocations of production. Hence, our study contributes to the assessment of sustainable industrial development, which is aimed by the Sustainability Development Goal “Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation countries”. By applying information on country-specific Human Development Indexes (reflecting aspects of life expectancy, education, and per capita income), we show that relocating energy-intensive industries from the EU may not only increase global energy demand and CO₂-emissions, but may also be to the disadvantage of developing countries. Y1 - 2020 U6 - https://doi.org/10.1016/j.apenergy.2020.114633 SN - 0306-2619 VL - 264 IS - Article number: 114633 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Wardoyo, Arinto Y.P. A1 - Noor, Johan A.E. A1 - Elbers, Gereon A1 - Schmitz, Sandra A1 - Flaig, Sascha T. A1 - Budianto, Arif T1 - Characterizing volcanic ash elements from the 2015 eruptions of bromo and raung volcanoes, Indonesia JF - Polish Journal of Environmental Studies N2 - The volcanic eruptions of Mt. Bromo and Mt. Raung in East Java, Indonesia, in 2015 perturbed volcanic materials and affected surface-layer air quality at surrounding locations. During the episodes, the volcanic ash from the eruptions influenced visibility, traffic accidents, flight schedules, and human health. In this research, the volcanic ash particles were collected and characterized by relying on the detail of physical observation. We performed an assessment of the volcanic ash elements to characterize the volcanic ash using two different methods which are aqua regia extracts followed by MP-AES and XRF laboratory test of bulk samples. The analysis results showed that the volcanic ash was mixed of many materials, such as Al, Si, P, K, Ca, Ti, V, Cr, Mn, Fe, Ni, and others. Fe, Si, Ca, and Al were found as the major elements, while the others were the trace elements Ba, Cr, Cu, Mn, P, Mn, Ni, Zn, Sb, Sr, and V with the minor concentrations. XRF analyses showed that Fe dominated the elements of the volcanic ash. The XRF analysis showed that Fe was at 35.40% in Bromo and 43.00% in Raung of the detected elements in bulk material. The results of aqua regia extracts analyzed by MP-AES were 1.80% and 1.70% of Fe element for Bromo and Raung volcanoes, respectively. Y1 - 2020 U6 - https://doi.org/10.15244/pjoes/99101 SN - 2083-5906 VL - 29 IS - 2 SP - 1899 EP - 1907 PB - HARD CY - Olsztyn ER - TY - JOUR A1 - Khayyam, Hamid A1 - Jamali, Ali A1 - Bab-Hadiashar, Alireza A1 - Esch, Thomas A1 - Ramakrishna, Seeram A1 - Jalil, Mahdi A1 - Naebe, Minoo T1 - A Novel Hybrid Machine Learning Algorithm for Limited and Big Data Modelling with Application in Industry 4.0 JF - IEEE Access N2 - To meet the challenges of manufacturing smart products, the manufacturing plants have been radically changed to become smart factories underpinned by industry 4.0 technologies. The transformation is assisted by employment of machine learning techniques that can deal with modeling both big or limited data. This manuscript reviews these concepts and present a case study that demonstrates the use of a novel intelligent hybrid algorithms for Industry 4.0 applications with limited data. In particular, an intelligent algorithm is proposed for robust data modeling of nonlinear systems based on input-output data. In our approach, a novel hybrid data-driven combining the Group-Method of Data-Handling and Singular-Value Decomposition is adapted to find an offline deterministic model combined with Pareto multi-objective optimization to overcome the overfitting issue. An Unscented-Kalman-Filter is also incorporated to update the coefficient of the deterministic model and increase its robustness against data uncertainties. The effectiveness of the proposed method is examined on a set of real industrial measurements. Y1 - 2020 SN - 2169-3536 U6 - https://doi.org/10.1109/ACCESS.2020.2999898 SP - 1 EP - 12 PB - IEEE CY - New York, NY ER - TY - JOUR A1 - Hailer, Benjamin A1 - Weber, Tobias A1 - Neveling, Sebastian A1 - Dera, Samuel A1 - Arent, Jan-Christoph A1 - Middendorf, Peter T1 - Development of a test device to determine the frictional behavior between honeycomb and prepreg layers under realistic manufacturing conditions JF - Journal of Sandwich Structures & Materials N2 - In the friction tests between honeycomb with film adhesive and prepreg, the relative displacement occurs between the film adhesive and the prepreg. The film adhesive does not shift relative to the honeycomb. This is consistent with the core crush behavior where the honeycomb moves together with the film adhesive, as can be seen in Figure 2(a). The pull-through forces of the friction measurements between honeycomb and prepreg at 1 mm deformation are plotted in Figure 17(a). While the friction at 100°C is similar to the friction at 120°C, it decreases significantly at 130°C and exhibits a minimum at 140°C. At 150°C, the friction rises again slightly and then sharply at 160°C. Since the viscosity of the M18/1 prepreg resin drops significantly before it cures [23], the minimum friction at 140°C could result from a minimum viscosity of the mixture of prepreg resin and film adhesive before the bond subsequently cures. Figure 17(b) shows the mean value curve of the friction measurements at 140°C. The error bars, which represent the standard deviation, reveal the good repeatability of the tests. The force curve is approximately horizontal between 1 mm and 2 mm. The friction then slightly rises. As with interlaminar friction measurements, this could be due to the fact that resin is removed by friction and the proportion of boundary lubrication increases. Figure 18 shows the surfaces after the friction measurement. The honeycomb cell walls are clearly visible in the film adhesive. There are areas where the film adhesive is completely removed and the carrier material of the film adhesive becomes visible. In addition, the viscosity of the resin changes as the curing progresses during the friction test. This can also affect the force-displacement curve. Y1 - 2020 U6 - https://doi.org/10.1177/1099636220923986 SN - 1530-7972 IS - Volume 23, Issue 7 SP - 3017 EP - 3043 PB - Sage CY - London ER - TY - JOUR A1 - Leise, Philipp A1 - Eßer, Arved A1 - Eichenlaub, Tobias A1 - Schleiffer, Jean-Eric A1 - Altherr, Lena A1 - Rinderknecht, Stephan A1 - Pelz, Peter F. T1 - Sustainable system design of electric powertrains - comparison of optimization methods JF - Engineering Optimization N2 - The transition within transportation towards battery electric vehicles can lead to a more sustainable future. To account for the development goal ‘climate action’ stated by the United Nations, it is mandatory, within the conceptual design phase, to derive energy-efficient system designs. One barrier is the uncertainty of the driving behaviour within the usage phase. This uncertainty is often addressed by using a stochastic synthesis process to derive representative driving cycles and by using cycle-based optimization. To deal with this uncertainty, a new approach based on a stochastic optimization program is presented. This leads to an optimization model that is solved with an exact solver. It is compared to a system design approach based on driving cycles and a genetic algorithm solver. Both approaches are applied to find efficient electric powertrains with fixed-speed and multi-speed transmissions. Hence, the similarities, differences and respective advantages of each optimization procedure are discussed. KW - Powertrain KW - stochastic optimization KW - global optimization KW - genetic algorithm Y1 - 2021 U6 - https://doi.org/10.1080/0305215X.2021.1928660 SN - 0305-215X PB - Taylor & Francis CY - London ER - TY - JOUR A1 - Kuerten, David A1 - Kotliar, Konstantin A1 - Fuest, Matthias A1 - Walter, Peter A1 - Hollstein, Muriel A1 - Plange, Niklas ED - Neri, Piergiorgio T1 - Does hemispheric vascular regulation differ significantly in glaucoma patients with altitudinal visual field asymmetry? A single-center, prospective study JF - International Ophthalmology N2 - Purpose Vascular risk factors and ocular perfusion are heatedly discussed in the pathogenesis of glaucoma. The retinal vessel analyzer (RVA, IMEDOS Systems, Germany) allows noninvasive measurement of retinal vessel regulation. Significant differences especially in the veins between healthy subjects and patients suffering from glaucoma were previously reported. In this pilot-study we investigated if localized vascular regulation is altered in glaucoma patients with altitudinal visual field defect asymmetry. Methods 15 eyes of 12 glaucoma patients with advanced altitudinal visual field defect asymmetry were included. The mean defect was calculated for each hemisphere separately (-20.99 ± 10.49 pro- found hemispheric visual field defect vs -7.36 ± 3.97 dB less profound hemisphere). After pupil dilation, RVA measurements of retinal arteries and veins were conducted using the standard protocol. The superior and inferior retinal vessel reactivity were measured consecutively in each eye. Results Significant differences were recorded in venous vessel constriction after flicker light stimulation and overall amplitude of the reaction (p \ 0.04 and p \ 0.02 respectively) in-between the hemispheres spheres. Vessel reaction was higher in the hemisphere corresponding to the more advanced visual field defect. Arterial diameters reacted similarly, failing to reach statistical significance. Conclusion Localized retinal vessel regulation is significantly altered in glaucoma patients with asymmetri altitudinal visual field defects. Veins supplying the hemisphere concordant to a less profound visual field defect show diminished diameter changes. Vascular dysregulation might be particularly important in early glaucoma stages prior to a significant visual field defect. KW - Glaucoma KW - Visual field asymmetry KW - Ocular blood flow KW - RVA KW - Vascular response Y1 - 2021 SN - 1573-2630 U6 - https://doi.org/10.1007/s10792-021-01876-0 VL - 41 IS - 41 SP - 3109 EP - 3119 PB - Springer CY - Berlin ER - TY - JOUR A1 - Albanna, Walid A1 - Conzen, Catharina A1 - Weiss, Miriam A1 - Seyfried, Katharina A1 - Kotliar, Konstantin A1 - Schmidt, Tobias Philip A1 - Kuerten, David A1 - Hescheler, Jürgen A1 - Bruecken, Anne A1 - Schmidt-Trucksäss, Arno A1 - Neumaier, Felix A1 - Wiesmann, Martin A1 - Clusmann, Hans A1 - Schubert, Gerrit Alexander T1 - Non-invasive assessment of neurovascular coupling after aneurysmal subarachnoid hemorrhage: a prospective observational trial using retinal vessel analysis JF - Frontiers in Neurology N2 - Delayed cerebral ischemia (DCI) is a common complication after aneurysmal subarachnoid hemorrhage (aSAH) and can lead to infarction and poor clinical outcome. The underlying mechanisms are still incompletely understood, but animal models indicate that vasoactive metabolites and inflammatory cytokines produced within the subarachnoid space may progressively impair and partially invert neurovascular coupling (NVC) in the brain. Because cerebral and retinal microvasculature are governed by comparable regulatory mechanisms and may be connected by perivascular pathways, retinal vascular changes are increasingly recognized as a potential surrogate for altered NVC in the brain. Here, we used non-invasive retinal vessel analysis (RVA) to assess microvascular function in aSAH patients at different times after the ictus. Y1 - 2021 U6 - https://doi.org/10.3389/fneur.2021.690183 SN - 1664-2295 VL - 12 IS - 12 SP - 1 EP - 15 ER - TY - JOUR A1 - Werfel, Stanislas A1 - Günthner, Roman A1 - Hapfelmeier, Alexander A1 - Hanssen, Henner A1 - Kotliar, Konstantin A1 - Heemann, Uwe A1 - Schmaderer, Christoph ED - Guzik, Tomasz J. T1 - Identification of cardiovascular high-risk groups from dynamic retinal vessel signals using untargeted machine learning JF - Cardiovascular Research N2 - Dynamic retinal vessel analysis (DVA) provides a non-invasive way to assess microvascular function in patients and potentially to improve predictions of individual cardiovascular (CV) risk. The aim of our study was to use untargeted machine learning on DVA in order to improve CV mortality prediction and identify corresponding response alterations. KW - Machine learning KW - Retinal vessels KW - Microcirculation KW - Haemodialysis KW - Myocardial infarction and cardiac death Y1 - 2022 U6 - https://doi.org/10.1093/cvr/cvab040 SN - 0008-6363 VL - 118 IS - 2 SP - 612 EP - 621 PB - Oxford University Press CY - Oxford ER - TY - JOUR A1 - Grundlach, Michael A1 - Baumann, Martin A1 - Engelmann, Ulrich M. ED - Dössel, Olaf T1 - How Multimodal Examinations Can Increase Sustainable Student Gain by Aligning Teaching and Assessment JF - Current Directions in Biomedical Engineering N2 - Modern industry and multi-discipline projects require highly trained individuals with resilient science and engineering back-grounds. Graduates must be able to agilely apply excellent theoretical knowledge in their subject matter as well as essential practical “hands-on” knowledge of diverse working processes to solve complex problems. To meet these demands, university education follows the concept of Constructive Alignment and thus increasingly adopts the teaching of necessary practical skills to the actual industry requirements and assessment routines. However, a systematic approach to coherently align these three central teaching demands is strangely absent from current university curricula. We demonstrate the feasibility of implementing practical assessments in a regular theory-based examination, thus defining the term “blended assessment”. We assessed a course for natural science and engineering students pursuing a career in biomedical engineering, and evaluated the benefit of blended assessment exams for students and lecturers. Our controlled study assessed the physiological background of electrocardiograms (ECGs), the practical measurement of ECG curves, and their interpretation of basic pathologic alterations. To study on long time effects, students have been assessed on the topic twice with a time lag of 6 months. Our findings suggest a significant improvement in student gain with respect to practical skills and theoretical knowledge. The results of the reassessments support these outcomes. From the lecturers ́ point of view, blended assessment complements practical training courses while keeping organizational effort manageable. We consider blended assessment a viable tool for providing an improved student gain, industry-ready education format that should be evaluated and established further to prepare university graduates optimally for their future careers. KW - constructive alignment KW - examination KW - long-term retention KW - multimodal KW - practical learning Y1 - 2021 SN - 2364-5504 U6 - https://doi.org/10.1515/cdbme-2021-2019 VL - 7 IS - 7/2 SP - 73 EP - 76 PB - De Gruyter CY - Berlin ER - TY - JOUR A1 - Altherr, Lena A1 - Ederer, Thorsten A1 - Lorenz, Ulf A1 - Pelz, Peter F. A1 - Pöttgen, Philipp ED - Lübbecke, Marco ED - Koster, Arie ED - Letmathe, Peter ED - Madlener, Reihard ED - Peis, Britta ED - Walther, Grit T1 - Experimental validation of an enhanced system synthesis approach JF - Operations Research Proceedings 2014 N2 - Planning the layout and operation of a technical system is a common task for an engineer. Typically, the workflow is divided into consecutive stages: First, the engineer designs the layout of the system, with the help of his experience or of heuristic methods. Secondly, he finds a control strategy which is often optimized by simulation. This usually results in a good operating of an unquestioned sys- tem topology. In contrast, we apply Operations Research (OR) methods to find a cost-optimal solution for both stages simultaneously via mixed integer program- ming (MILP). Technical Operations Research (TOR) allows one to find a provable global optimal solution within the model formulation. However, the modeling error due to the abstraction of physical reality remains unknown. We address this ubiq- uitous problem of OR methods by comparing our computational results with mea- surements in a test rig. For a practical test case we compute a topology and control strategy via MILP and verify that the objectives are met up to a deviation of 8.7%. Y1 - 2014 SN - 978-3-319-28695-2 U6 - https://doi.org/10.1007/978-3-319-28697-6_1 PB - Springer CY - Basel ER - TY - JOUR A1 - Sun, Hui A1 - Altherr, Lena A1 - Pei, Ji A1 - Pelz, Peter F. A1 - Yuan, Shouqi T1 - Optimal booster station design and operation under uncertain load JF - Applied Mechanics and Materials N2 - Given industrial applications, the costs for the operation and maintenance of a pump system typically far exceed its purchase price. For finding an optimal pump configuration which minimizes not only investment, but life-cycle costs, methods like Technical Operations Research which is based on Mixed-Integer Programming can be applied. However, during the planning phase, the designer is often faced with uncertain input data, e.g. future load demands can only be estimated. In this work, we deal with this uncertainty by developing a chance-constrained two-stage (CCTS) stochastic program. The design and operation of a booster station working under uncertain load demand are optimized to minimize total cost including purchase price, operation cost incurred by energy consumption and penalty cost resulting from water shortage. We find optimized system layouts using a sample average approximation (SAA) algorithm, and analyze the results for different risk levels of water shortage. By adjusting the risk level, the costs and performance range of the system can be balanced, and thus the system’s resilience can be engineered KW - Stochastic Programming KW - Chance Constraint KW - Engineering Application KW - Pump System KW - Water Distribution Y1 - 2018 U6 - https://doi.org/10.4028/www.scientific.net/AMM.885.102 SN - 1662-7482 VL - 885 SP - 102 EP - 115 PB - Trans Tech Publications CY - Bäch ER - TY - JOUR A1 - Altherr, Lena A1 - Brötz, Nicolas A1 - Dietrich, Ingo A1 - Gally, Tristan A1 - Geßner, Felix A1 - Kloberdanz, Hermann A1 - Leise, Philipp A1 - Pelz, Peter Franz A1 - Schlemmer, Pia A1 - Schmitt, Andreas T1 - Resilience in mechanical engineering - a concept for controlling uncertainty during design, production and usage phase of load-carrying structures JF - Applied Mechanics and Materials N2 - Resilience as a concept has found its way into different disciplines to describe the ability of an individual or system to withstand and adapt to changes in its environment. In this paper, we provide an overview of the concept in different communities and extend it to the area of mechanical engineering. Furthermore, we present metrics to measure resilience in technical systems and illustrate them by applying them to load-carrying structures. By giving application examples from the Collaborative Research Centre (CRC) 805, we show how the concept of resilience can be used to control uncertainty during different stages of product life. Y1 - 2018 SN - 1662-7482 U6 - https://doi.org/10.4028/www.scientific.net/AMM.885.187 VL - 885 SP - 187 EP - 198 PB - Trans Tech Publications CY - Bäch ER - TY - JOUR A1 - Rausch, Lea A1 - Friesen, John A1 - Altherr, Lena A1 - Meck, Marvin A1 - Pelz, Peter F. T1 - A holistic concept to design optimal water supply infrastructures for informal settlements using remote sensing data JF - Remote Sensing N2 - Ensuring access to water and sanitation for all is Goal No. 6 of the 17 UN Sustainability Development Goals to transform our world. As one step towards this goal, we present an approach that leverages remote sensing data to plan optimal water supply networks for informal urban settlements. The concept focuses on slums within large urban areas, which are often characterized by a lack of an appropriate water supply. We apply methods of mathematical optimization aiming to find a network describing the optimal supply infrastructure. Hereby, we choose between different decentral and central approaches combining supply by motorized vehicles with supply by pipe systems. For the purposes of illustration, we apply the approach to two small slum clusters in Dhaka and Dar es Salaam. We show our optimization results, which represent the lowest cost water supply systems possible. Additionally, we compare the optimal solutions of the two clusters (also for varying input parameters, such as population densities and slum size development over time) and describe how the result of the optimization depends on the entered remote sensing data. KW - water supply design KW - mathematical optimization KW - slum classification KW - remote sensing Y1 - 2018 SN - 2072-4292 U6 - https://doi.org/10.3390/rs10020216 VL - 10 IS - 2 SP - 1 EP - 23 PB - MDPI CY - Basel ER - TY - JOUR A1 - Altherr, Lena A1 - Joggerst, Laura A1 - Leise, Philipp A1 - Pfetsch, Marc E. A1 - Schmitt, Andreas A1 - Wendt, Janine T1 - On obligations in the development process of resilient systems with algorithmic design methods JF - Applied Mechanics and Materials N2 - Advanced computational methods are needed both for the design of large systems and to compute high accuracy solutions. Such methods are efficient in computation, but the validation of results is very complex, and highly skilled auditors are needed to verify them. We investigate legal questions concerning obligations in the development phase, especially for technical systems developed using advanced methods. In particular, we consider methods of resilient and robust optimization. With these techniques, high performance solutions can be found, despite a high variety of input parameters. However, given the novelty of these methods, it is uncertain whether legal obligations are being met. The aim of this paper is to discuss if and how the choice of a specific computational method affects the developer’s product liability. The review of legal obligations in this paper is based on German law and focuses on the requirements that must be met during the design and development process. KW - legal obligations KW - product liability KW - design of technical systems KW - optimization KW - resilience Y1 - 2018 SN - 1662-7482 U6 - https://doi.org/10.4028/www.scientific.net/AMM.885.240 VL - 885 IS - 885 SP - 240 EP - 252 PB - Trans Tech Publications CY - Bäch ER - TY - JOUR A1 - Pöttgen, Philipp A1 - Ederer, Thorsten A1 - Altherr, Lena A1 - Pelz, Peter F. T1 - Developing a control strategy for booster stations under uncertain load JF - Applied Mechanics and Materials N2 - Booster stations can fulfill a varying pressure demand with high energy-efficiency, because individual pumps can be deactivated at smaller loads. Although this is a seemingly simple approach, it is not easy to decide precisely when to activate or deactivate pumps. Contemporary activation controls derive the switching points from the current volume flow through the system. However, it is not measured directly for various reasons. Instead, the controller estimates the flow based on other system properties. This causes further uncertainty for the switching decision. In this paper, we present a method to find a robust, yet energy-efficient activation strategy. KW - Technical Operations Research (TOR) KW - Booster Station KW - Pump System KW - Discrete Optimization Y1 - 2015 SN - 1662-7482 U6 - https://doi.org/10.4028/www.scientific.net/AMM.807.241 N1 - Ebenfalls weltweit einsehbar unter: http://wl.fst.tu-darmstadt.de/wl/publications/paper_151123_SFB805_ ICUME_Developing_a_Control_Strategy_for_Booster_Stations_under_Uncertain_Load_poettgen_ederer_pelz_altherr.pdf VL - 807 IS - 807 SP - 241 EP - 246 PB - Trans Tech Publications CY - Bäch ER - TY - JOUR A1 - Pöttgen, Philipp A1 - Ederer, Thorsten A1 - Altherr, Lena A1 - Lorenz, Ulf A1 - Pelz, Peter F. T1 - Examination and optimization of a heating circuit for energy-efficient buildings JF - Energy Technology N2 - The conference center darmstadtium in Darmstadt is a prominent example of energy efficient buildings. Its heating system consists of different source and consumer circuits connected by a Zortström reservoir. Our goal was to reduce the energy costs of the system as much as possible. Therefore, we analyzed its supply circuits. The first step towards optimization is a complete examination of the system: 1) Compilation of an object list for the system, 2) collection of the characteristic curves of the components, and 3) measurement of the load profiles of the heat and volume-flow demand. Instead of modifying the system manually and testing the solution by simulation, the second step was the creation of a global optimization program. The objective was to minimize the total energy costs for one year. We compare two different topologies and show opportunities for significant savings. KW - energy transfer KW - heating system KW - programming KW - system optimization KW - technical operations research Y1 - 2015 SN - 2194-4296 U6 - https://doi.org/10.1002/ente.201500252 VL - 4 IS - 1 SP - 136 EP - 144 PB - WILEY-VCH Verlag CY - Weinheim ER - TY - JOUR A1 - Altherr, Lena A1 - Ederer, Thorsten A1 - Pöttgen, Philipp A1 - Lorenz, Ulf A1 - Pelz, Peter F. ED - Pelz, Peter F. ED - Groche, Peter T1 - Multicriterial optimization of technical systems considering multiple load and availability scenarios JF - Applied Mechanics and Materials N2 - Cheap does not imply cost-effective -- this is rule number one of zeitgeisty system design. The initial investment accounts only for a small portion of the lifecycle costs of a technical system. In fluid systems, about ninety percent of the total costs are caused by other factors like power consumption and maintenance. With modern optimization methods, it is already possible to plan an optimal technical system considering multiple objectives. In this paper, we focus on an often neglected contribution to the lifecycle costs: downtime costs due to spontaneous failures. Consequently, availability becomes an issue. KW - sustainability KW - availability KW - energy efficiency KW - mixed-integer linear programming KW - system synthesis Y1 - 2015 SN - 1660-9336 U6 - https://doi.org/10.4028/www.scientific.net/AMM.807.247 VL - 807 SP - 247 EP - 256 ER - TY - JOUR A1 - Kurz, Melanie T1 - Images of Sweden in Germany: from Sundborn and Bullerby to Ikea JF - nomad: the magazine for new design culture, business affairs and contemporary lifestyle Y1 - 2019 SN - 2513-0714 IS - 8 SP - 136 EP - 147 ER - TY - JOUR A1 - Monakhova, Yulia A1 - Diehl, Bernd W.K. T1 - Nuclear magnetic resonance spectroscopy as an elegant tool for a complete quality control of crude heparin material JF - Journal of Pharmaceutical and Biomedical Analysis N2 - Nuclear magnetic resonance (NMR) spectrometric methods for the quantitative analysis of pure heparin in crude heparin is proposed. For quantification, a two-step routine was developed using a USP heparin reference sample for calibration and benzoic acid as an internal standard. The method was successfully validated for its accuracy, reproducibility, and precision. The methodology was used to analyze 20 authentic porcine heparinoid samples having heparin content between 4.25 w/w % and 64.4 w/w %. The characterization of crude heparin products was further extended to a simultaneous analysis of these common ions: sodium, calcium, acetate and chloride. A significant, linear dependence was found between anticoagulant activity and assayed heparin content for thirteen heparinoids samples, for which reference data were available. A Diffused-ordered NMR experiment (DOSY) can be used for qualitative analysis of specific glycosaminoglycans (GAGs) in heparinoid matrices and, potentially, for quantitative prediction of molecular weight of GAGs. NMR spectrometry therefore represents a unique analytical method suitable for the simultaneous quantitative control of organic and inorganic composition of crude heparin samples (especially heparin content) as well as an estimation of other physical and quality parameters (molecular weight, animal origin and activity). KW - NMR spectroscopy KW - Heparin KW - Crude heparin KW - USP KW - Ions Y1 - 2022 U6 - https://doi.org/10.1016/j.jpba.2022.114915 SN - 0731-7085 VL - 219 IS - Article number: 114915 PB - Elsevier CY - New York, NY ER - TY - JOUR A1 - Uysal, Karya A1 - Creutz, Till A1 - Firat, Ipek Seda A1 - Artmann, Gerhard A1 - Teusch, Nicole A1 - Temiz Artmann, Aysegül T1 - Bio-functionalized ultra-thin, large-area and waterproof silicone membranes for biomechanical cellular loading and compliance experiments JF - Polymers N2 - Biocompatibility, flexibility and durability make polydimethylsiloxane (PDMS) membranes top candidates in biomedical applications. CellDrum technology uses large area, <10 µm thin membranes as mechanical stress sensors of thin cell layers. For this to be successful, the properties (thickness, temperature, dust, wrinkles, etc.) must be precisely controlled. The following parameters of membrane fabrication by means of the Floating-on-Water (FoW) method were investigated: (1) PDMS volume, (2) ambient temperature, (3) membrane deflection and (4) membrane mechanical compliance. Significant differences were found between all PDMS volumes and thicknesses tested (p < 0.01). They also differed from the calculated values. At room temperatures between 22 and 26 °C, significant differences in average thickness values were found, as well as a continuous decrease in thicknesses within a 4 °C temperature elevation. No correlation was found between the membrane thickness groups (between 3–4 µm) in terms of deflection and compliance. We successfully present a fabrication method for thin bio-functionalized membranes in conjunction with a four-step quality management system. The results highlight the importance of tight regulation of production parameters through quality control. The use of membranes described here could also become the basis for material testing on thin, viscous layers such as polymers, dyes and adhesives, which goes far beyond biological applications. Y1 - 2022 SN - 2073-4360 VL - 14 IS - 11 SP - 2213 PB - MDPI CY - Basel ER - TY - JOUR A1 - Abbas, Karim A1 - Balc, Nicolae A1 - Bremen, Sebastian A1 - Skupin, Marco T1 - Crystallization and aging behavior of polyetheretherketone PEEK within rapid tooling and rubber molding JF - Journal of Manufacturing and Materials Processing N2 - In times of short product life cycles, additive manufacturing and rapid tooling are important methods to make tool development and manufacturing more efficient. High-performance polymers are the key to mold production for prototypes and small series. However, the high temperatures during vulcanization injection molding cause thermal aging and can impair service life. The extent to which the thermal stress over the entire process chain stresses the material and whether it leads to irreversible material aging is evaluated. To this end, a mold made of PEEK is fabricated using fused filament fabrication and examined for its potential application. The mold is heated to 200 ◦C, filled with rubber, and cured. A differential scanning calorimetry analysis of each process step illustrates the crystallization behavior and first indicates the material resistance. It shows distinct cold crystallization regions at a build chamber temperature of 90 ◦C. At an ambient temperature above Tg, crystallization of 30% is achieved, and cold crystallization no longer occurs. Additional tensile tests show a decrease in tensile strength after ten days of thermal aging. The steady decrease in recrystallization temperature indicates degradation of the additives. However, the tensile tests reveal steady embrittlement of the material due to increasing crosslinking. KW - additive manufacturing KW - fused filament fabrication KW - crystallization KW - polyetheretherketone KW - rapid tooling Y1 - 2022 U6 - https://doi.org/10.3390/jmmp6050093 SN - 2504-4494 N1 - The article belongs to the Special Issue Advances in Injection Molding: Process, Materials and Applications VL - 6 IS - 5 SP - 1 EP - 12 PB - MDPI CY - Basel ER - TY - JOUR A1 - Topçu, Murat A1 - Madabhushi, Gopal S.P. A1 - Staat, Manfred T1 - A generalized shear-lag theory for elastic stress transfer between matrix and fibres having a variable radius JF - International Journal of Solids and Structures N2 - A generalized shear-lag theory for fibres with variable radius is developed to analyse elastic fibre/matrix stress transfer. The theory accounts for the reinforcement of biological composites, such as soft tissue and bone tissue, as well as for the reinforcement of technical composite materials, such as fibre-reinforced polymers (FRP). The original shear-lag theory proposed by Cox in 1952 is generalized for fibres with variable radius and with symmetric and asymmetric ends. Analytical solutions are derived for the distribution of axial and interfacial shear stress in cylindrical and elliptical fibres, as well as conical and paraboloidal fibres with asymmetric ends. Additionally, the distribution of axial and interfacial shear stress for conical and paraboloidal fibres with symmetric ends are numerically predicted. The results are compared with solutions from axisymmetric finite element models. A parameter study is performed, to investigate the suitability of alternative fibre geometries for use in FRP. KW - Natural fibres KW - Polymer-matrix composites KW - Biocomposites KW - Stress concentrations KW - Finite element analysis Y1 - 2022 U6 - https://doi.org/10.1016/j.ijsolstr.2022.111464 SN - 0020-7683 VL - 239–240 IS - Art. No. 111464 PB - Elsevier CY - New York, NY ER - TY - JOUR A1 - Mandekar, Swati A1 - Holland, Abigail A1 - Thielen, Moritz A1 - Behbahani, Mehdi A1 - Melnykowycz, Mark T1 - Advancing towards Ubiquitous EEG, Correlation of In-Ear EEG with Forehead EEG JF - Sensors N2 - Wearable EEG has gained popularity in recent years driven by promising uses outside of clinics and research. The ubiquitous application of continuous EEG requires unobtrusive form-factors that are easily acceptable by the end-users. In this progression, wearable EEG systems have been moving from full scalp to forehead and recently to the ear. The aim of this study is to demonstrate that emerging ear-EEG provides similar impedance and signal properties as established forehead EEG. EEG data using eyes-open and closed alpha paradigm were acquired from ten healthy subjects using generic earpieces fitted with three custom-made electrodes and a forehead electrode (at Fpx) after impedance analysis. Inter-subject variability in in-ear electrode impedance ranged from 20 kΩ to 25 kΩ at 10 Hz. Signal quality was comparable with an SNR of 6 for in-ear and 8 for forehead electrodes. Alpha attenuation was significant during the eyes-open condition in all in-ear electrodes, and it followed the structure of power spectral density plots of forehead electrodes, with the Pearson correlation coefficient of 0.92 between in-ear locations ELE (Left Ear Superior) and ERE (Right Ear Superior) and forehead locations, Fp1 and Fp2, respectively. The results indicate that in-ear EEG is an unobtrusive alternative in terms of impedance, signal properties and information content to established forehead EEG. KW - in-ear EEG KW - correlation KW - forehead EEG KW - impedance spectroscopy KW - biopotential electrodes Y1 - 2022 U6 - https://doi.org/10.3390/s22041568 SN - 1424-8220 VL - 22 IS - 4 SP - 1 EP - 19 PB - MDPI CY - Basel ER - TY - JOUR A1 - Defosse, Jerome A1 - Kleinschmidt, Joris A1 - Schmutz, Axel A1 - Loop, Torsten A1 - Staat, Manfred A1 - Gatzweiler, Karl-Heinz A1 - Wappler, Frank A1 - Schieren, Mark T1 - Dental strain on maxillary incisors during tracheal intubation with double-lumen tubes and different laryngoscopy techniques - a blinded manikin study JF - Journal of Cardiothoracic and Vascular Anesthesia KW - anaesthetic complications KW - dental trauma KW - difficult airway KW - double-lumen tube intubation KW - videolaryngoscopy Y1 - 2022 U6 - https://doi.org/10.1053/j.jvca.2022.02.017 SN - 1053-0770 VL - 36 IS - 8, Part B SP - 3021 EP - 3027 PB - Elsevier CY - New York, NY ER - TY - JOUR A1 - Peloni, Alessandro A1 - Ceriotti, Matteo A1 - Dachwald, Bernd T1 - Solar-sail trajectory design for a multiple near-earth-asteroid rendezvous mission JF - Journal of Guidance, Control, and Dynamics N2 - The scientific interest for near-Earth asteroids as well as the interest in potentially hazardous asteroids from the perspective of planetary defense led the space community to focus on near-Earth asteroid mission studies. A multiple near-Earth asteroid rendezvous mission with close-up observations of several objects can help to improve the characterization of these asteroids. This work explores the design of a solar-sail spacecraft for such a mission, focusing on the search of possible sequences of encounters and the trajectory optimization. This is done in two sequential steps: a sequence search by means of a simplified trajectory model and a set of heuristic rules based on astrodynamics, and a subsequent optimization phase. A shape-based approach for solar sailing has been developed and is used for the first phase. The effectiveness of the proposed approach is demonstrated through a fully optimized multiple near-Earth asteroid rendezvous mission. The results show that it is possible to visit five near-Earth asteroids within 10 years with near-term solar-sail technology. Y1 - 2016 U6 - https://doi.org/10.2514/1.G000470 SN - 0731-5090 VL - 39 IS - 12 SP - 2712 EP - 2724 PB - AIAA CY - Reston, Va. ER - TY - JOUR A1 - Bhattarai, Aroj A1 - May, Charlotte Anabell A1 - Staat, Manfred A1 - Kowalczyk, Wojciech A1 - Tran, Thanh Ngoc T1 - Layer-specific damage modeling of porcine large intestine under biaxial tension JF - Bioengineering N2 - The mechanical behavior of the large intestine beyond the ultimate stress has never been investigated. Stretching beyond the ultimate stress may drastically impair the tissue microstructure, which consequently weakens its healthy state functions of absorption, temporary storage, and transportation for defecation. Due to closely similar microstructure and function with humans, biaxial tensile experiments on the porcine large intestine have been performed in this study. In this paper, we report hyperelastic characterization of the large intestine based on experiments in 102 specimens. We also report the theoretical analysis of the experimental results, including an exponential damage evolution function. The fracture energies and the threshold stresses are set as damage material parameters for the longitudinal muscular, the circumferential muscular and the submucosal collagenous layers. A biaxial tensile simulation of a linear brick element has been performed to validate the applicability of the estimated material parameters. The model successfully simulates the biomechanical response of the large intestine under physiological and non-physiological loads. KW - biaxial tensile experiment KW - anisotropy KW - hyperelastic KW - constitutive modeling KW - damage Y1 - 2022 U6 - https://doi.org/10.3390/bioengineering9100528 SN - 2306-5354 N1 - Der Artikel gehört zum Sonderheft "Computational Biomechanics" VL - 9 IS - 10, Early Access SP - 1 EP - 17 PB - MDPI CY - Basel ER - TY - JOUR A1 - Colombo, Daniele A1 - Drira, Slah A1 - Frotscher, Ralf A1 - Staat, Manfred T1 - An element-based formulation for ES-FEM and FS-FEM models for implementation in standard solid mechanics finite element codes for 2D and 3D static analysis JF - International Journal for Numerical Methods in Engineering N2 - Edge-based and face-based smoothed finite element methods (ES-FEM and FS-FEM, respectively) are modified versions of the finite element method allowing to achieve more accurate results and to reduce sensitivity to mesh distortion, at least for linear elements. These properties make the two methods very attractive. However, their implementation in a standard finite element code is nontrivial because it requires heavy and extensive modifications to the code architecture. In this article, we present an element-based formulation of ES-FEM and FS-FEM methods allowing to implement the two methods in a standard finite element code with no modifications to its architecture. Moreover, the element-based formulation permits to easily manage any type of element, especially in 3D models where, to the best of the authors' knowledge, only tetrahedral elements are used in FS-FEM applications found in the literature. Shape functions for non-simplex 3D elements are proposed in order to apply FS-FEM to any standard finite element. KW - distorted element KW - ES-FEM KW - FS-FEM KW - non-simplex S-FEM elements KW - S-FEM Y1 - 2022 U6 - https://doi.org/10.1002/nme.7126 SN - 1097-0207 VL - 124 IS - 2 SP - 402 EP - 433 PB - Wiley CY - Chichester ER - TY - JOUR A1 - Kotliar, Konstantin A1 - Ortner, Marion A1 - Conradi, Anna A1 - Hacker, Patricia A1 - Hauser, Christine A1 - Günthner, Roman A1 - Moser, Michaela A1 - Muggenthaler, Claudia A1 - Diehl-Schmid, Janine A1 - Priller, Josef A1 - Schmaderer, Christoph A1 - Grimmer, Timo T1 - Altered retinal cerebral vessel oscillation frequencies in Alzheimer's disease compatible with impaired amyloid clearance JF - Neurobiology of Aging N2 - Retinal vessels are similar to cerebral vessels in their structure and function. Moderately low oscillation frequencies of around 0.1 Hz have been reported as the driving force for paravascular drainage in gray matter in mice and are known as the frequencies of lymphatic vessels in humans. We aimed to elucidate whether retinal vessel oscillations are altered in Alzheimer's disease (AD) at the stage of dementia or mild cognitive impairment (MCI). Seventeen patients with mild-to-moderate dementia due to AD (ADD); 23 patients with MCI due to AD, and 18 cognitively healthy controls (HC) were examined using Dynamic Retinal Vessel Analyzer. Oscillatory temporal changes of retinal vessel diameters were evaluated using mathematical signal analysis. Especially at moderately low frequencies around 0.1 Hz, arterial oscillations in ADD and MCI significantly prevailed over HC oscillations and correlated with disease severity. The pronounced retinal arterial vasomotion at moderately low frequencies in the ADD and MCI groups would be compatible with the view of a compensatory upregulation of paravascular drainage in AD and strengthen the amyloid clearance hypothesis. KW - Alzheimer's disease KW - Retinal vessel analysis KW - Vasomotions KW - Pulsations KW - Mild cognitive impairment Y1 - 2022 U6 - https://doi.org/10.1016/j.neurobiolaging.2022.08.012 SN - 0197-4580 VL - 120 SP - 117 EP - 127 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Maurischat, Andreas T1 - Algebraic independence of the Carlitz period and its hyperderivatives JF - Journal of Number Theory KW - Drinfeld modules KW - Periods KW - t-modules KW - Transcendence KW - Higher derivations Y1 - 2022 U6 - https://doi.org/10.1016/j.jnt.2022.01.006 SN - 0022-314X VL - 240 SP - 145 EP - 162 PB - Elsevier CY - Orlando, Fla. ER - TY - JOUR A1 - Philipp, Mohr A1 - Efthimiou, Nikos A1 - Pagano, Fiammetta A1 - Kratochwil, Nicolaus A1 - Pizzichemi, Marco A1 - Tsoumpas, Charalampos A1 - Auffray, Etiennette A1 - Ziemons, Karl T1 - Image reconstruction analysis for positron emission tomography with heterostructured scintillators JF - IEEE Transactions on Radiation and Plasma Medical Sciences N2 - The concept of structure engineering has been proposed for exploring the next generation of radiation detectors with improved performance. A TOF-PET geometry with heterostructured scintillators with a pixel size of 3.0×3.1×15 mm3 was simulated using Monte Carlo. The heterostructures consisted of alternating layers of BGO as a dense material with high stopping power and plastic (EJ232) as a fast light emitter. The detector time resolution was calculated as a function of the deposited and shared energy in both materials on an event-by-event basis. While sensitivity was reduced to 32% for 100 μm thick plastic layers and 52% for 50 μm, the CTR distribution improved to 204±49 ps and 220±41 ps respectively, compared to 276 ps that we considered for bulk BGO. The complex distribution of timing resolutions was accounted for in the reconstruction. We divided the events into three groups based on their CTR and modeled them with different Gaussian TOF kernels. On a NEMA IQ phantom, the heterostructures had better contrast recovery in early iterations. On the other hand, BGO achieved a better contrast to noise ratio (CNR) after the 15th iteration due to the higher sensitivity. The developed simulation and reconstruction methods constitute new tools for evaluating different detector designs with complex time responses. KW - TOF PET KW - Heterostructure KW - Metascintillator KW - Multiple TOF kernels KW - Image Reconstruction Y1 - 2022 U6 - https://doi.org/10.1109/TRPMS.2022.3208615 SN - 2469-7311 SN - 2469-7303 VL - 7 IS - 1 SP - 41 EP - 51 PB - IEEE CY - New York, NY ER - TY - JOUR A1 - Pourshahidi, Ali Mohammad A1 - Engelmann, Ulrich M. A1 - Offenhäusser, Andreas A1 - Krause, Hans-Joachim T1 - Resolving ambiguities in core size determination of magnetic nanoparticles from magnetic frequency mixing data JF - Journal of Magnetism and Magnetic Materials N2 - Frequency mixing magnetic detection (FMMD) has been widely utilized as a measurement technique in magnetic immunoassays. It can also be used for the characterization and distinction (also known as “colourization”) of different types of magnetic nanoparticles (MNPs) based on their core sizes. In a previous work, it was shown that the large particles contribute most of the FMMD signal. This leads to ambiguities in core size determination from fitting since the contribution of the small-sized particles is almost undetectable among the strong responses from the large ones. In this work, we report on how this ambiguity can be overcome by modelling the signal intensity using the Langevin model in thermodynamic equilibrium including a lognormal core size distribution fL(dc,d0,σ) fitted to experimentally measured FMMD data of immobilized MNPs. For each given median diameter d0, an ambiguous amount of best-fitting pairs of parameters distribution width σ and number of particles Np with R2 > 0.99 are extracted. By determining the samples’ total iron mass, mFe, with inductively coupled plasma optical emission spectrometry (ICP-OES), we are then able to identify the one specific best-fitting pair (σ, Np) one uniquely. With this additional externally measured parameter, we resolved the ambiguity in core size distribution and determined the parameters (d0, σ, Np) directly from FMMD measurements, allowing precise MNPs sample characterization. Y1 - 2022 U6 - https://doi.org/10.1016/j.jmmm.2022.169969 SN - 0304-8853 VL - 563 IS - In progress, Art. No. 169969 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Engelmann, Ulrich M. A1 - Pourshahidi, Mohammad Ali A1 - Shalaby, Ahmed A1 - Krause, Hans-Joachim T1 - Probing particle size dependency of frequency mixing magnetic detection with dynamic relaxation simulation JF - Journal of Magnetism and Magnetic Materials N2 - Biomedical applications of magnetic nanoparticles (MNP) fundamentally rely on the particles’ magnetic relaxation as a response to an alternating magnetic field. The magnetic relaxation complexly depends on the interplay of MNP magnetic and physical properties with the applied field parameters. It is commonly accepted that particle core size is a major contributor to signal generation in all the above applications, however, most MNP samples comprise broad distribution spanning nm and more. Therefore, precise knowledge of the exact contribution of individual core sizes to signal generation is desired for optimal MNP design generally for each application. Specifically, we present a magnetic relaxation simulation-driven analysis of experimental frequency mixing magnetic detection (FMMD) for biosensing to quantify the contributions of individual core size fractions towards signal generation. Applying our method to two different experimental MNP systems, we found the most dominant contributions from approx. 20 nm sized particles in the two independent MNP systems. Additional comparison between freely suspended and immobilized MNP also reveals insight in the MNP microstructure, allowing to use FMMD for MNP characterization, as well as to further fine-tune its applicability in biosensing. Y1 - 2022 U6 - https://doi.org/10.1016/j.jmmm.2022.169965 SN - 0304-8853 VL - 563 IS - In progress, Art. No. 169965 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Steuer-Dankert, Linda A1 - Sharma, Mamta Rameshwarlal A1 - Bleck, Wolfgang A1 - Leicht-Scholten, Carmen T1 - Diversity and innovation management in large research groups JF - International Journal of Innovation Management N2 - Contemporary research appreciates a diverse workforce as a potential source of innovation. Researchers explore the fine details of why diversity management is central for generating innovations in heterogeneous research groups and how it could be effectively implemented into organizations. Complex research associations that discuss topics with a high impact on society increasingly address the necessity of establishing a diverse workforce to confront the challenges of tomorrow. Characterized by complex management structures as well as hierarchies, research associations have not been a subject of investigation until now. For this reason, the presented research project aims to develop a diversity and innovation management strategy with the ultimate goal of inducing change in the corporate culture. The proposed approach consisted of six phases; the first two phases investigated the status quo of diversity in the existing organizational structures of member institutes and the variety of particular working cultures within the research association. The third and the fourth phases utilized qualitative and quantitative studies. The third phase focused on the connection of management level to diversity and innovation, and the need for diversity and innovation management, and tailor-made methods of implementing them. The first three phases have been accomplished successfully; preliminary results are already available. The fourth phase will mainly focus on exploring the mind-set of the employees. The fifth phase will consolidate the findings in the first four phases into an implementable strategy. The final phase will address the implementation of this strategy into the organization. Phases 4 to 6 have not yet been undertaken KW - diversity management KW - innovation management KW - research association KW - change management KW - engineering Y1 - 2017 SN - 1757-5877 VL - 5 IS - 2 SP - 49 EP - 72 ER - TY - JOUR A1 - Steuer-Dankert, Linda A1 - Gilmartin, Shannon K. A1 - Muller, Carol B. A1 - Dungs, Carolin A1 - Sheppard, Sheri A1 - Leicht-Scholten, Carmen T1 - Expanding engineering limits : a concept for socially responsible education of engineers JF - The international journal of engineering education Y1 - 2019 SN - 0949-149X VL - 35 IS - 2 SP - 658 EP - 673 ER - TY - JOUR A1 - Czarnecki, Christian A1 - Spiliopoulou, Myra T1 - A holistic framework for the implementation of a next generation network JF - International Journal of Business Information Systems N2 - As the potential of a next generation network (NGN) is recognised, telecommunication companies consider switching to it. Although the implementation of an NGN seems to be merely a modification of the network infrastructure, it may trigger or require changes in the whole company, because it builds upon the separation between service and transport, a flexible bundling of services to products and the streamlining of the IT infrastructure. We propose a holistic framework, structured into the layers ‘strategy’, ‘processes’ and ‘information systems’ and incorporate into each layer all concepts necessary for the implementation of an NGN, as well as the alignment of these concepts. As a first proof-of-concept for our framework we have performed a case study on the introduction of NGN in a large telecommunication company; we show that our framework captures all topics that are affected by an NGN implementation. KW - next generation network KW - telecommunication KW - NGN KW - IP-based networks KW - product bundling Y1 - 2012 U6 - https://doi.org/10.1504/IJBIS.2012.046291 SN - 1746-0972 VL - 9 IS - 4 SP - 385 EP - 401 PB - Inderscience Enterprises CY - Olney, Bucks ER - TY - JOUR A1 - Czarnecki, Christian A1 - Winkelmann, Axel A1 - Spiliopoulou, Myra T1 - Services in electronic telecommunication markets: a framework for planning the virtualization of processes JF - Electronic Markets N2 - The potential of electronic markets in enabling innovative product bundles through flexible and sustainable partnerships is not yet fully exploited in the telecommunication industry. One reason is that bundling requires seamless de-assembling and re-assembling of business processes, whilst processes in telecommunication companies are often product-dependent and hard to virtualize. We propose a framework for the planning of the virtualization of processes, intended to assist the decision maker in prioritizing the processes to be virtualized: (a) we transfer the virtualization pre-requisites stated by the Process Virtualization Theory in the context of customer-oriented processes in the telecommunication industry and assess their importance in this context, (b) we derive IT-oriented requirements for the removal of virtualization barriers and highlight their demand on changes at different levels of the organization. We present a first evaluation of our approach in a case study and report on lessons learned and further steps to be performed. KW - Telecommunication KW - Services KW - Process virtualization KW - Product bundling KW - Transformation Y1 - 2010 U6 - https://doi.org/10.1007/s12525-010-0045-8 SN - 1422-8890 VL - 20 IS - 3-4 SP - 197 EP - 207 PB - Springer CY - Berlin ER - TY - JOUR A1 - Lindner, Simon A1 - Burger, René A1 - Rutledge, Douglas N. A1 - Do, Xuan Tung A1 - Rumpf, Jessica A1 - Diehl, Bernd W. K. A1 - Schulze, Margit A1 - Monakhova, Yulia T1 - Is the calibration transfer of multivariate calibration models between high- and low-field NMR instruments possible? A case study of lignin molecular weight JF - Analytical chemistry N2 - Although several successful applications of benchtop nuclear magnetic resonance (NMR) spectroscopy in quantitative mixture analysis exist, the possibility of calibration transfer remains mostly unexplored, especially between high- and low-field NMR. This study investigates for the first time the calibration transfer of partial least squares regressions [weight average molecular weight (Mw) of lignin] between high-field (600 MHz) NMR and benchtop NMR devices (43 and 60 MHz). For the transfer, piecewise direct standardization, calibration transfer based on canonical correlation analysis, and transfer via the extreme learning machine auto-encoder method are employed. Despite the immense resolution difference between high-field and low-field NMR instruments, the results demonstrate that the calibration transfer from high- to low-field is feasible in the case of a physical property, namely, the molecular weight, achieving validation errors close to the original calibration (down to only 1.2 times higher root mean square errors). These results introduce new perspectives for applications of benchtop NMR, in which existing calibrations from expensive high-field instruments can be transferred to cheaper benchtop instruments to economize. Y1 - 2022 SN - 1520-6882 U6 - https://doi.org/10.1021/acs.analchem.1c05125 VL - 94 IS - 9 SP - 3997 EP - 4004 PB - ACS Publications CY - Washington, DC ER - TY - JOUR A1 - Monakhova, Yulia A1 - Diehl, Bernd W.K. T1 - Multinuclear NMR screening of pharmaceuticals using standardization by 2H integral of a deuterated solvent JF - Journal of Pharmaceutical and Biomedical Analysis N2 - NMR standardization approach that uses the 2H integral of deuterated solvent for quantitative multinuclear analysis of pharmaceuticals is described. As a proof of principle, the existing NMR procedure for the analysis of heparin products according to US Pharmacopeia monograph is extended to the determination of Na+ and Cl- content in this matrix. Quantification is performed based on the ratio of a 23Na (35Cl) NMR integral and 2H NMR signal of deuterated solvent, D2O, acquired using the specific spectrometer hardware. As an alternative, the possibility of 133Cs standardization using the addition of Cs2CO3 stock solution is shown. Validation characteristics (linearity, repeatability, sensitivity) are evaluated. A holistic NMR profiling of heparin products can now also be used for the quantitative determination of inorganic compounds in a single analytical run using a single sample. In general, the new standardization methodology provides an appealing alternative for the NMR screening of inorganic and organic components in pharmaceutical products. KW - NMR spectroscopy KW - Inorganic ions KW - Heparin KW - Standardization Y1 - 2022 SN - 0731-7085 U6 - https://doi.org/10.1016/j.jpba.2021.114530 VL - 209 IS - Article number: 114530 PB - Elsevier ER - TY - JOUR A1 - Burger, René A1 - Lindner, Simon A1 - Rumpf, Jessica A1 - Do, Xuan Tung A1 - Diehl, Bernd W.K. A1 - Rehahn, Matthias A1 - Monakhova, Yulia A1 - Schulze, Margit T1 - Benchtop versus high field NMR: Comparable performance found for the molecular weight determination of lignin JF - Journal of Pharmaceutical and Biomedical Analysis N2 - Lignin is a promising renewable biopolymer being investigated worldwide as an environmentally benign substitute of fossil-based aromatic compounds, e.g. for the use as an excipient with antioxidant and antimicrobial properties in drug delivery or even as active compound. For its successful implementation into process streams, a quick, easy, and reliable method is needed for its molecular weight determination. Here we present a method using 1H spectra of benchtop as well as conventional NMR systems in combination with multivariate data analysis, to determine lignin’s molecular weight (Mw and Mn) and polydispersity index (PDI). A set of 36 organosolv lignin samples (from Miscanthus x giganteus, Paulownia tomentosa and Silphium perfoliatum) was used for the calibration and cross validation, and 17 samples were used as external validation set. Validation errors between 5.6% and 12.9% were achieved for all parameters on all NMR devices (43, 60, 500 and 600 MHz). Surprisingly, no significant difference in the performance of the benchtop and high-field devices was found. This facilitates the application of this method for determining lignin’s molecular weight in an industrial environment because of the low maintenance expenditure, small footprint, ruggedness, and low cost of permanent magnet benchtop NMR systems. KW - NMR KW - PLS-regression KW - Molecular weight determination KW - Chemometrics KW - Biomass Y1 - 2022 SN - 0731-7085 U6 - https://doi.org/10.1016/j.jpba.2022.114649 VL - 212 IS - Article number: 114649 PB - Elsevier CY - New York, NY ER - TY - JOUR A1 - Monakhova, Yulia A1 - Soboleva, Polina M. A1 - Fedotova, Elena S. A1 - Musina, Kristina T. A1 - Burmistrova, Natalia A. T1 - Quantum chemical calculations of IR spectra of heparin disaccharide subunits JF - Computational and Theoretical Chemistry N2 - Heparin is a natural polysaccharide, which plays essential role in many biological processes. Alterations in building blocks can modify biological roles of commercial heparin products, due to significant changes in the conformation of the polymer chain. The variability structure of heparin leads to difficulty in quality control using different analytical methods, including infrared (IR) spectroscopy. In this paper molecular modelling of heparin disaccharide subunits was performed using quantum chemistry. The structural and spectral parameters of these disaccharides have been calculated using RHF/6-311G. In addition, over-sulphated chondroitin sulphate disaccharide was studied as one of the most widespread contaminants of heparin. Calculated IR spectra were analyzed with respect to specific structure parameters. IR spectroscopic fingerprint was found to be sensitive to substitution pattern of disaccharide subunits. Vibrational assignments of calculated spectra were correlated with experimental IR spectral bands of native heparin. Chemometrics was used to perform multivariate analysis of simulated spectral data. KW - IR spectroscopy KW - Chemometrics KW - Quantum chemistry KW - Molecular modelling KW - Quality control Y1 - 2022 SN - 2210-271X U6 - https://doi.org/10.1016/j.comptc.2022.113891 VL - 1217 IS - Article number: 113891 PB - Elsevier CY - New York, NY ER - TY - JOUR A1 - Monakhova, Yulia A1 - Diehl, Bernd W.K. T1 - Novel approach of qNMR workflow by standardization using 2H integral: Application to any intrinsic calibration standard JF - Talanta N2 - Quantitative nuclear magnetic resonance (qNMR) is routinely performed by the internal or external standardization. The manuscript describes a simple alternative to these common workflows by using NMR signal of another active nuclei of calibration compound. For example, for any arbitrary compound quantification by NMR can be based on the use of an indirect concentration referencing that relies on a solvent having both 1H and 2H signals. To perform high-quality quantification, the deuteration level of the utilized deuterated solvent has to be estimated. In this contribution the new method was applied to the determination of deuteration levels in different deuterated solvents (MeOD, ACN, CDCl3, acetone, benzene, DMSO-d6). Isopropanol-d6, which contains a defined number of deuterons and protons, was used for standardization. Validation characteristics (precision, accuracy, robustness) were calculated and the results showed that the method can be used in routine practice. Uncertainty budget was also evaluated. In general, this novel approach, using standardization by 2H integral, benefits from reduced sample preparation steps and uncertainties, and can be applied in different application areas (purity determination, forensics, pharmaceutical analysis, etc.). KW - qNMR KW - Deuterium NMR KW - Deuterated solvents KW - Standardization Y1 - 2021 SN - 0039-9140 U6 - https://doi.org/10.1016/j.talanta.2020.121504 VL - 222 IS - Article number: 121504 PB - Elsevier ER - TY - JOUR A1 - Burmistrova, Natalia A. A1 - Soboleva, Polina M. A1 - Monakhova, Yulia T1 - Is infrared spectroscopy combined with multivariate analysis a promising tool for heparin authentication? JF - Journal of Pharmaceutical and Biomedical Analysis N2 - The investigation of the possibility to determine various characteristics of powder heparin (n = 115) was carried out with infrared spectroscopy. The evaluation of heparin samples included several parameters such as purity grade, distributing company, animal source as well as heparin species (i.e. Na-heparin, Ca-heparin, and heparinoids). Multivariate analysis using principal component analysis (PCA), soft independent modelling of class analogy (SIMCA), and partial least squares – discriminant analysis (PLS-DA) were applied for the modelling of spectral data. Different pre-processing methods were applied to IR spectral data; multiplicative scatter correction (MSC) was chosen as the most relevant. Obtained results were confirmed by nuclear magnetic resonance (NMR) spectroscopy. Good predictive ability of this approach demonstrates the potential of IR spectroscopy and chemometrics for screening of heparin quality. This approach, however, is designed as a screening tool and is not considered as a replacement for either of the methods required by USP and FDA. KW - IR spectroscopy KW - Heparin KW - Authenticity KW - Principal component analysis KW - Soft independent modeling of class analogy Y1 - 2021 SN - 0731-7085 U6 - https://doi.org/10.1016/j.jpba.2020.113811 VL - 194 IS - Article number: 113811 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Monakhova, Yulia A1 - Diehl, Bernd W. K. T1 - Simplification of NMR Workflows by Standardization Using 2H Integral of Deuterated Solvent as Applied to Aloe vera Preparations JF - Applied Magnetic Resonance N2 - In this study, a recently proposed NMR standardization approach by 2H integral of deuterated solvent for quantitative multicomponent analysis of complex mixtures is presented. As a proof of principle, the existing NMR routine for the analysis of Aloe vera products was modified. Instead of using absolute integrals of targeted compounds and internal standard (nicotinamide) from 1H-NMR spectra, quantification was performed based on the ratio of a particular 1H-NMR compound integral and 2H-NMR signal of deuterated solvent D2O. Validation characteristics (linearity, repeatability, accuracy) were evaluated and the results showed that the method has the same precision as internal standardization in case of multicomponent screening. Moreover, a dehydration process by freeze drying is not necessary for the new routine. Now, our NMR profiling of A. vera products needs only limited sample preparation and data processing. The new standardization methodology provides an appealing alternative for multicomponent NMR screening. In general, this novel approach, using standardization by 2H integral, benefits from reduced sample preparation steps and uncertainties, and is recommended in different application areas (purity determination, forensics, pharmaceutical analysis, etc.). Y1 - 2021 U6 - https://doi.org/10.1007/s00723-021-01393-4 SN - 1613-7507 VL - 52 IS - 11 SP - 1591 EP - 1600 PB - Springer CY - Cham ER - TY - JOUR A1 - Burger, René A1 - Rumpf, Jessica A1 - Do, Xuan Tung A1 - Monakhova, Yulia A1 - Diehl, Bernd W. K. A1 - Rehahn, Matthias A1 - Schulze, Margit T1 - Is NMR combined with multivariate regression applicable for the molecular weight determination of randomly cross-linked polymers such as lignin? JF - ACS Omega N2 - The molecular weight properties of lignins are one of the key elements that need to be analyzed for a successful industrial application of these promising biopolymers. In this study, the use of 1H NMR as well as diffusion-ordered spectroscopy (DOSY NMR), combined with multivariate regression methods, was investigated for the determination of the molecular weight (Mw and Mn) and the polydispersity of organosolv lignins (n = 53, Miscanthus x giganteus, Paulownia tomentosa, and Silphium perfoliatum). The suitability of the models was demonstrated by cross validation (CV) as well as by an independent validation set of samples from different biomass origins (beech wood and wheat straw). CV errors of ca. 7–9 and 14–16% were achieved for all parameters with the models from the 1H NMR spectra and the DOSY NMR data, respectively. The prediction errors for the validation samples were in a similar range for the partial least squares model from the 1H NMR data and for a multiple linear regression using the DOSY NMR data. The results indicate the usefulness of NMR measurements combined with multivariate regression methods as a potential alternative to more time-consuming methods such as gel permeation chromatography. Y1 - 2021 U6 - https://doi.org/10.1021/acsomega.1c03574 SN - 2470-1343 VL - 6 IS - 44 SP - 29516 EP - 29524 PB - ACS Publications CY - Washington, DC ER - TY - JOUR A1 - Mueller, Tobias A1 - Segin, Alexander A1 - Weigand, Christoph A1 - Schmitt, Robert H. T1 - Feature selection for measurement models JF - International journal of quality & reliability management N2 - Purpose In the determination of the measurement uncertainty, the GUM procedure requires the building of a measurement model that establishes a functional relationship between the measurand and all influencing quantities. Since the effort of modelling as well as quantifying the measurement uncertainties depend on the number of influencing quantities considered, the aim of this study is to determine relevant influencing quantities and to remove irrelevant ones from the dataset. Design/methodology/approach In this work, it was investigated whether the effort of modelling for the determination of measurement uncertainty can be reduced by the use of feature selection (FS) methods. For this purpose, 9 different FS methods were tested on 16 artificial test datasets, whose properties (number of data points, number of features, complexity, features with low influence and redundant features) were varied via a design of experiments. Findings Based on a success metric, the stability, universality and complexity of the method, two FS methods could be identified that reliably identify relevant and irrelevant influencing quantities for a measurement model. Originality/value For the first time, FS methods were applied to datasets with properties of classical measurement processes. The simulation-based results serve as a basis for further research in the field of FS for measurement models. The identified algorithms will be applied to real measurement processes in the future. KW - Feature selection KW - Modelling KW - Measurement models KW - Measurement uncertainty Y1 - 2022 U6 - https://doi.org/10.1108/IJQRM-07-2021-0245 SN - 0265-671X IS - Vol. ahead-of-print, No. ahead-of-print. PB - Emerald Group Publishing Limited CY - Bingley ER - TY - JOUR A1 - Rübbelke, Dirk A1 - Vögele, Stefan A1 - Grajewski, Matthias A1 - Zobel, Luzy T1 - Hydrogen-based steel production and global climate protection: An empirical analysis of the potential role of a European cross border adjustment mechanism JF - Journal of Cleaner Production N2 - The European Union's aim to become climate neutral by 2050 necessitates ambitious efforts to reduce carbon emissions. Large reductions can be attained particularly in energy intensive sectors like iron and steel. In order to prevent the relocation of such industries outside the EU in the course of tightening environmental regulations, the establishment of a climate club jointly with other large emitters and alternatively the unilateral implementation of an international cross-border carbon tax mechanism are proposed. This article focuses on the latter option choosing the steel sector as an example. In particular, we investigate the financial conditions under which a European cross border mechanism is capable to protect hydrogen-based steel production routes employed in Europe against more polluting competition from abroad. By using a floor price model, we assess the competitiveness of different steel production routes in selected countries. We evaluate the climate friendliness of steel production on the basis of specific GHG emissions. In addition, we utilize an input-output price model. It enables us to assess impacts of rising cost of steel production on commodities using steel as intermediates. Our results raise concerns that a cross-border tax mechanism will not suffice to bring about competitiveness of hydrogen-based steel production in Europe because the cost tends to remain higher than the cost of steel production in e.g. China. Steel is a classic example for a good used mainly as intermediate for other products. Therefore, a cross-border tax mechanism for steel will increase the price of products produced in the EU that require steel as an input. This can in turn adversely affect competitiveness of these sectors. Hence, the effects of higher steel costs on European exports should be borne in mind and could require the cross-border adjustment mechanism to also subsidize exports. Y1 - 2022 U6 - https://doi.org/10.1016/j.jclepro.2022.135040 SN - 0959-6526 VL - 380 IS - Part 2, Art. Nr.:135040 PB - Elsevier ER - TY - JOUR A1 - Tran, Ngoc Trinh A1 - Trinh, Tu Luc A1 - Dao, Ngoc Tien A1 - Giap, Van Tan A1 - Truong, Manh Khuyen A1 - Dinh, Thuy Ha A1 - Staat, Manfred T1 - FEM shakedown analysis of structures under random strength with chance constrained programming JF - Vietnam Journal of Mechanics N2 - Direct methods, comprising limit and shakedown analysis, are a branch of computational mechanics. They play a significant role in mechanical and civil engineering design. The concept of direct methods aims to determine the ultimate load carrying capacity of structures beyond the elastic range. In practical problems, the direct methods lead to nonlinear convex optimization problems with a large number of variables and constraints. If strength and loading are random quantities, the shakedown analysis can be formulated as stochastic programming problem. In this paper, a method called chance constrained programming is presented, which is an effective method of stochastic programming to solve shakedown analysis problems under random conditions of strength. In this study, the loading is deterministic, and the strength is a normally or lognormally distributed variable. KW - limit analysis KW - shakedown analysis KW - chance constrained programming KW - stochastic programming KW - reliability of structures Y1 - 2022 U6 - https://doi.org/10.15625/0866-7136/17943 SN - 0866-7136 SN - 2815-5882 VL - 44 IS - 4 SP - 459 EP - 473 PB - Vietnam Academy of Science and Technology (VAST) ER - TY - JOUR A1 - Baringhaus, Ludwig A1 - Gaigall, Daniel T1 - A goodness-of-fit test for the compound Poisson exponential model JF - Journal of Multivariate Analysis N2 - On the basis of bivariate data, assumed to be observations of independent copies of a random vector (S,N), we consider testing the hypothesis that the distribution of (S,N) belongs to the parametric class of distributions that arise with the compound Poisson exponential model. Typically, this model is used in stochastic hydrology, with N as the number of raindays, and S as total rainfall amount during a certain time period, or in actuarial science, with N as the number of losses, and S as total loss expenditure during a certain time period. The compound Poisson exponential model is characterized in the way that a specific transform associated with the distribution of (S,N) satisfies a certain differential equation. Mimicking the function part of this equation by substituting the empirical counterparts of the transform we obtain an expression the weighted integral of the square of which is used as test statistic. We deal with two variants of the latter, one of which being invariant under scale transformations of the S-part by fixed positive constants. Critical values are obtained by using a parametric bootstrap procedure. The asymptotic behavior of the tests is discussed. A simulation study demonstrates the performance of the tests in the finite sample case. The procedure is applied to rainfall data and to an actuarial dataset. A multivariate extension is also discussed. KW - Bootstrapping KW - Collective risk model Y1 - 2022 U6 - https://doi.org/10.1016/j.jmva.2022.105154 SN - 0047-259X SN - 1095-7243 VL - 195 IS - Article 105154 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Levers, A. A1 - Staat, Manfred A1 - Laack, Walter van T1 - Analysis of the long-term effect of the MBST® nuclear magnetic resonance therapy on gonarthrosis JF - Orthopedic Practice Y1 - 2016 VL - 47 IS - 11 SP - 521 EP - 528 ER - TY - JOUR A1 - Koster, Arie A1 - Scheidweiler, Robert A1 - Tieves, Martin T1 - A flow based pruning scheme for enumerative equitable coloring algorithms JF - A flow based pruning scheme for enumerative equitable coloring algorithms N2 - An equitable graph coloring is a proper vertex coloring of a graph G where the sizes of the color classes differ by at most one. The equitable chromatic number is the smallest number k such that G admits such equitable k-coloring. We focus on enumerative algorithms for the computation of the equitable coloring number and propose a general scheme to derive pruning rules for them: We show how the extendability of a partial coloring into an equitable coloring can be modeled via network flows. Thus, we obtain pruning rules which can be checked via flow algorithms. Computational experiments show that the search tree of enumerative algorithms can be significantly reduced in size by these rules and, in most instances, such naive approach even yields a faster algorithm. Moreover, the stability, i.e., the number of solved instances within a given time limit, is greatly improved. Since the execution of flow algorithms at each node of a search tree is time consuming, we derive arithmetic pruning rules (generalized Hall-conditions) from the network model. Adding these rules to an enumerative algorithm yields an even larger runtime improvement. Y1 - 2016 U6 - https://doi.org/10.48550/arXiv.1607.08754 N1 - Lehrstuhl II für Mathematik, RWTH Aachen University SP - 1 EP - 30 ER - TY - JOUR A1 - Beckenbach, Isabel A1 - Scheidweiler, Robert T1 - Perfect ƒ-Matchings and ƒ-Factors in Hypergraphs - A Combinatorial Approach JF - Discrete Mathematics N2 - We prove characterizations of the existence of perfect ƒ-matchings in uniform mengerian and perfect hypergraphs. Moreover, we investigate the ƒ-factor problem in balanced hypergraphs. For uniform balanced hypergraphs we prove two existence theorems with purely combinatorial arguments, whereas for non-uniform balanced hypergraphs we show that the ƒ-factor problem is NP-hard. Y1 - 2016 U6 - https://doi.org/10.1016/j.disc.2017.05.005 SN - 2192-7782 N1 - Als Volltext auch bei ZIB (Zuse Institute Berlin) VL - 240 IS - 10 SP - 2499 EP - 2506 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Scheidweiler, Robert A1 - Triesch, Eberhard T1 - A note on the duality between matchings and vertex covers in balanced hypergraphs JF - Journal of Combinatorial Optimization N2 - We present a new Min-Max theorem for an optimization problem closely connected to matchings and vertex covers in balanced hypergraphs. The result generalizes Kőnig’s Theorem (Berge and Las Vergnas in Ann N Y Acad Sci 175:32–40, 1970; Fulkerson et al. in Math Progr Study 1:120–132, 1974) and Hall’s Theorem (Conforti et al. in Combinatorica 16:325–329, 1996) for balanced hypergraphs. KW - Hall’s Theorem KW - Koenig’s Theorem KW - Duality KW - Balanced hypergraph KW - Hypergraph KW - Vertex cover KW - Matching Y1 - 2016 U6 - https://doi.org/10.1007/s10878-015-9887-5 SN - 1573-2886 N1 - Lehrstuhl II für Mathematik RWTH Aachen VL - 32 IS - 2 SP - 639 EP - 644 PB - Springer CY - Berlin ER - TY - JOUR A1 - Niedermeyer, Angela A1 - Zhou, Bei A1 - Dursun, Gözde A1 - Temiz Artmann, Aysegül A1 - Markert, Bernd T1 - An examination of tissue engineered scaffolds in a bioreactor JF - Proceedings in Applied Mathematics and Mechanics PAMM N2 - Replacement tissues, designed to fill in articular cartilage defects, should exhibit the same properties as the native material. The aim of this study is to foster the understanding of, firstly, the mechanical behavior of the material itself and, secondly, the influence of cultivation parameters on cell seeded implants as well as on cell migration into acellular implants. In this study, acellular cartilage replacement material is theoretically, numerically and experimentally investigated regarding its viscoelastic properties, where a phenomenological model for practical applications is developed. Furthermore, remodeling and cell migration are investigated. Y1 - 2016 U6 - https://doi.org/10.1002/pamm.201610038 SN - 1617-7061 N1 - Joint Annual Meeting of DMV and GAMM 2016, 87th Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM) and Deutsche Mathematiker-Vereinigung (DMV), Braunschweig, DE, Mar 7-11, 2016 VL - 16 IS - 1 SP - 99 EP - 100 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Kilic, S. A. A1 - Raatschen, Hans-Jürgen A1 - Körfgen, B. A1 - Apaydin, N. M. A1 - Astaneh-Asl, A. T1 - FE Model of the Fatih Sultan Mehmet Suspension Bridge Using Thin Shell Finite Elements JF - Arabian Journal for Science and Engineering N2 - This paper presents the results of an eigenvalue analysis of the Fatih Sultan Mehmet Bridge. A high-resolution finite element model was created directly from the available design documents. All physical properties of the structural components were included in detail, so no calibration to the measured data was necessary. The deck and towers were modeled with shell elements. A nonlinear static analysis was performed before the eigenvalue calculation. The calculated natural frequencies and corresponding mode shapes showed good agreement with the available measured ambient vibration data. The calculation of the effective modal mass showed that nine modes had single contributions higher than 5 % of the total mass. They were in a frequency range up to 1.2 Hz. The comparison of the results for the torsional modes especially demonstrated the advantage of using thin shell finite elements over the beam modeling approach. KW - Suspension bridge KW - 3D nonlinear finite element model KW - Thin shell finite elements KW - Natural frequency KW - Effective modal mass Y1 - 2017 U6 - https://doi.org/10.1007/s13369-016-2316-y SN - 2191-4281 VL - 42 IS - 3 SP - 1103 EP - 1116 PB - Springer Nature ER - TY - JOUR A1 - Dantism, Shahriar A1 - Takenaga, Shoko A1 - Wagner, Torsten A1 - Wagner, Patrick A1 - Schöning, Michael Josef T1 - Differential imaging of the metabolism of bacteria and eukaryotic cells based on light-addressable potentiometric sensors JF - Electrochimica Acta N2 - A light-addressable potentiometric sensor (LAPS) is a field-effect-based potentiometric sensor with an electrolyte/insulator/semiconductor (EIS) structure, which is able to monitor analyte concentrations of (bio-)chemical species in aqueous solutions in a spatially resolved way. Therefore, it is also an appropriate tool to record 2D-chemical images of concentration variations on the sensor surface. In the present work, two differential, LAPS-based measurement principles are introduced to determine the metabolic activity of Escherichia coli (E. coli) K12 and Chinese hamster ovary (CHO) cells as test microorganisms. Hereby, we focus on i) the determination of the extracellular acidification rate (ΔpH/min) after adding glucose solutions to the cell suspensions; and ii) recording the amplitude increase of the photocurrent (Iph) related to the produced acids from E. coli K12 bacteria and CHO cells on the sensor surface by 2D-chemical imaging. For this purpose, 3D-printed multi-chamber structures were developed and mounted on the planar sensor-chip surface to define four independent compartments, enabling differential measurements with varying cell concentrations. The differential concept allows eliminating unwanted drift effects and, with the four-chamber structures, measurements on the different cell concentrations were performed simultaneously, thus reducing also the overall measuring time. Y1 - 2017 U6 - https://doi.org/10.1016/j.electacta.2017.05.196 SN - 0013-4686 VL - 246 SP - 234 EP - 241 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Jildeh, Zaid B. A1 - Kirchner, Patrick A1 - Oberländer, Jan A1 - Kremers, Alexander A1 - Wagner, Torsten A1 - Wagner, Patrick H. A1 - Schöning, Michael Josef T1 - FEM-based modeling of a calorimetric gas sensor for hydrogen peroxide monitoring JF - physica status solidi a : applications and materials sciences N2 - A physically coupled finite element method (FEM) model is developed to study the response behavior of a calorimetric gas sensor. The modeled sensor serves as a monitoring device of the concentration of gaseous hydrogen peroxide (H2 O2) in a high temperature mixture stream in aseptic sterilization processes. The principle of operation of a calorimetric H2 O2 sensor is analyzed and the results of the numerical model have been validated by using previously published sensor experiments. The deviation in the results between the FEM model and experimental data are presented and discussed. Y1 - 2017 U6 - https://doi.org/10.1002/pssa.201600912 SN - 1862-6319 IS - Early View PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Molinnus, Denise A1 - Poghossian, Arshak A1 - Keusgen, Michael A1 - Katz, Evgeny A1 - Schöning, Michael Josef T1 - Coupling of Biomolecular Logic Gates with Electronic Transducers: From Single Enzyme Logic Gates to Sense/Act/Treat Chips JF - Electroanalysis N2 - The integration of biomolecular logic principles with electronic transducers allows designing novel digital biosensors with direct electrical output, logically triggered drug-release, and closed-loop sense/act/treat systems. This opens new opportunities for advanced personalized medicine in the context of theranostics. In the present work, we will discuss selected examples of recent developments in the field of interfacing enzyme logic gates with electrodes and semiconductor field-effect devices. Special attention is given to an enzyme OR/Reset logic gate based on a capacitive field-effect electrolyte-insulator-semiconductor sensor modified with a multi-enzyme membrane. Further examples are a digital adrenaline biosensor based on an AND logic gate with binary YES/NO output and an integrated closed-loop sense/act/treat system comprising an amperometric glucose sensor, a hydrogel actuator, and an insulin (drug) sensor. Y1 - 2017 U6 - https://doi.org/10.1002/elan.201700208 SN - 1521-4109 VL - 29 IS - 8 SP - 1840 EP - 1849 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Arreola, Julio A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Effect of O2 plasma on properties of electrolyte-insulator-semiconductor structures JF - physica status solidi a : applications and materials sciences N2 - Prior to immobilization of biomolecules or cells onto biosensor surfaces, the surface must be physically or chemically activated for further functionalization. Organosilanes are a versatile option as they facilitate the immobilization through their terminal groups and also display self-assembly. Incorporating hydroxyl groups is one of the important methods for primary immobilization. This can be done, for example, with oxygen plasma treatment. However, this treatment can affect the performance of the biosensors and this effect is not quite well understood for surface functionalization. In this work, the effect of O2 plasma treatment on EIS sensors was investigated by means of electrochemical characterizations: capacitance–voltage (C–V) and constant capacitance (ConCap) measurements. After O2 plasma treatment, the potential of the EIS sensor dramatically shifts to a more negative value. This was successfully reset by using an annealing process. KW - surface functionalization KW - O2 plasma KW - hydroxylation KW - electrolyte-insulator semiconductor sensor (EIS) KW - annealing Y1 - 2017 U6 - https://doi.org/10.1002/pssa.201700025 SN - 1862-6319 VL - 214 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Miyamoto, Ko-ichiro A1 - Hayashi, Kosuke A1 - Sakamoto, Azuma A1 - Werner, Frederik A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - A high-Q resonance-mode measurement of EIS capacitive sensor by elimination of series resistance JF - Sensor and Actuators B: Chemical N2 - An EIS capacitive sensor is a semiconductor-based potentiometric sensor, which is sensitive to the ion concentration or pH value of the solution in contact with the sensing surface. To detect a small change in the ion concentration or pH, a small capacitance change must be detected. Recently, a resonance-mode measurement was proposed, in which an inductor was connected to the EIS capacitive sensor and the resonant frequency was correlated with the pH value. In this study, the Q factor of the resonant circuit was enhanced by canceling the internal resistance of the reference electrode and the internal resistance of the inductor coil with the help of a bypass capacitor and a negative impedance converter, respectively. 1% variation of the signal in the developed system corresponded to a pH change of 3.93 mpH, which was about 1/12 of the conventional method, suggesting a better performance in detection of a small pH change. KW - Negative impedance convertor KW - Resonance-mode measurement KW - Chemical sensor KW - EIS capacitive sensor Y1 - 2017 U6 - https://doi.org/10.1016/j.snb.2017.03.002 SN - 0925-4005 VL - 248 SP - 1006 EP - 1010 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Werner, Frederik A1 - Miyamoto, Ko-ichiro A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - Lateral resolution enhancement of pulse-driven light-addressable potentiometric sensor JF - Sensor and Actuators B: Chemical N2 - To study chemical and biological processes, spatially resolved determination of the concentrations of one or more analyte species is of distinct interest. With a light-addressable potentiometric sensor (LAPS), chemical images can be created, which visualize the concentration distribution above the sensor plate. One important challenge is to achieve a good lateral resolution in order to detect events that take place in a small and limited region. LAPS utilizes a focused light spot to address the measurement region. By moving this light spot along the semiconductor sensor plate, the concentration distribution can be observed. In this study, we show that utilizing a pulse as light excitation instead of a traditionally used continuously modulated light excitation, the lateral resolution can be improved by a factor of 6 or more. KW - Chemical images KW - LAPS KW - Light-addressable potentiometric sensor Y1 - 2017 U6 - https://doi.org/10.1016/j.snb.2017.02.057 SN - 0925-4005 VL - 248 SP - 961 EP - 965 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Scholl, Fabio A1 - Morais, Paulo A1 - Gabriel, Rayla A1 - Schöning, Michael Josef A1 - Siqueira, Jose Roberto, Jr. A1 - Caseli, Luciano T1 - Carbon nanotubes arranged as smart interfaces in lipid Langmuir-Blodgett films enhancing the enzymatic properties of penicillinase for biosensing applications JF - Applied Materials & Interfaces N2 - In this paper, carbon nanotubes (CNTs) were incorporated in penicillinase-phospholipid Langmuir and Langmuir–Blodgett (LB) films to enhance the enzyme catalytic properties. Adsorption of the penicillinase and CNTs at dimyristoylphosphatidic acid (DMPA) monolayers at the air–water interface was investigated by surface pressure–area isotherms, vibrational spectroscopy, and Brewster angle microscopy. The floating monolayers were transferred to solid supports through the LB technique, forming mixed DMPA-CNTs-PEN films, which were investigated by quartz crystal microbalance, vibrational spectroscopy, and atomic force microscopy. Enzyme activity was studied with UV–vis spectroscopy and the feasibility of the supramolecular device nanostructured as ultrathin films were essayed in a capacitive electrolyte–insulator–semiconductor (EIS) sensor device. The presence of CNTs in the enzyme–lipid LB film not only tuned the catalytic activity of penicillinase but also helped conserve its enzyme activity after weeks, showing increased values of activity. Viability as penicillin sensor was demonstrated with capacitance/voltage and constant capacitance measurements, exhibiting regular and distinctive output signals over all concentrations used in this work. These results may be related not only to the nanostructured system provided by the film, but also to the synergism between the compounds on the active layer, leading to a surface morphology that allowed a fast analyte diffusion because of an adequate molecular accommodation, which also preserved the penicillinase activity. This work therefore demonstrates the feasibility of employing LB films composed of lipids, CNTs, and enzymes as EIS devices for biosensing applications. Y1 - 2017 U6 - https://doi.org/10.1021/acsami.7b08095 SN - 1944-8252 VL - 9 IS - 36 SP - 31054 EP - 31066 PB - ACS CY - Washington ER - TY - JOUR A1 - Tran, Linda A1 - Mottaghy, K. A1 - Arlt-Körfer, Sabine A1 - Waluga, Christian A1 - Behbahani, Mehdi T1 - An experimental study of shear-dependent human platelet adhesion and underlying protein-binding mechanisms in a cylindrical Couette system JF - Biomedizinische Technik Y1 - 2017 U6 - https://doi.org/10.1515/bmt-2015-0034 SN - 0013-5585 VL - 62 IS - 4 SP - 383 EP - 392 PB - De Gruyter CY - Berlin ER - TY - JOUR A1 - Wulfhorst, Helene A1 - Duwe, Anna-Maria A1 - Merseburg, Johannes A1 - Tippkötter, Nils T1 - Compositional analysis of pretreated (beech) wood using differential scanning calorimetry and multivariate data analysis JF - Tetrahedron N2 - The composition of plant biomass varies depending on the feedstock and pre-treatment conditions and influences its processing in biorefineries. In order to ensure optimal process conditions, the quantitative proportion of the main polymeric components of the pre-treated biomass has to be determined. Current standard procedures for biomass compositional analysis are complex, the measurements are afflicted with errors and therefore often not comparable. Hence, new powerful analytical methods are urgently required to characterize biomass. In this contribution, Differential Scanning Calorimetry (DSC) was applied in combination with multivariate data analysis (MVA) to detect the cellulose content of the plant biomass pretreated by Liquid Hot Water (LHW) and Organosolv processes under various conditions. Unlike conventional techniques, the developed analytic method enables the accurate quantification of monosaccharide content of the plant biomass without any previous sample preparation. It is easy to handle and avoids errors in sample preparation. Y1 - 2016 U6 - https://doi.org/10.1016/j.tet.2016.04.029 VL - 72 IS - 46 SP - 7329 EP - 7334 PB - Elsevier CY - Amsterdam ER -