@article{JablonskiPoghossianSeverinetal.2021, author = {Jablonski, Melanie and Poghossian, Arshak and Severin, Robin and Keusgen, Michael and Wege, Christian and Sch{\"o}ning, Michael Josef}, title = {Capacitive Field-Effect Biosensor Studying Adsorption of Tobacco Mosaic Virus Particles}, series = {Micromachines}, volume = {12}, journal = {Micromachines}, number = {1}, publisher = {MDPI}, address = {Basel}, doi = {10.3390/mi12010057}, pages = {Artikel 57}, year = {2021}, abstract = {Plant virus-like particles, and in particular, tobacco mosaic virus (TMV) particles, are increasingly being used in nano- and biotechnology as well as for biochemical sensing purposes as nanoscaffolds for the high-density immobilization of receptor molecules. The sensitive parameters of TMV-assisted biosensors depend, among others, on the density of adsorbed TMV particles on the sensor surface, which is affected by both the adsorption conditions and surface properties of the sensor. In this work, Ta₂O₅-gate field-effect capacitive sensors have been applied for the label-free electrical detection of TMV adsorption. The impact of the TMV concentration on both the sensor signal and the density of TMV particles adsorbed onto the Ta₂O₅-gate surface has been studied systematically by means of field-effect and scanning electron microscopy methods. In addition, the surface density of TMV particles loaded under different incubation times has been investigated. Finally, the field-effect sensor also demonstrates the label-free detection of penicillinase immobilization as model bioreceptor on TMV particles.}, language = {en} } @article{HarzheimMuehmelHeuermann2021, author = {Harzheim, Thomas and M{\"u}hmel, Marc and Heuermann, Holger}, title = {A SFCW harmonic radar system for maritime search and rescue using passive and active tags}, series = {International Journal of Microwave and Wireless Technologies}, volume = {13}, journal = {International Journal of Microwave and Wireless Technologies}, number = {Special Issue 7}, publisher = {Cambridge University Press}, address = {Cambridge}, doi = {10.1017/S1759078721000520}, pages = {691 -- 707}, year = {2021}, abstract = {This paper introduces a new maritime search and rescue system based on S-band illumination harmonic radar (HR). Passive and active tags have been developed and tested while attached to life jackets and a small boat. In this demonstration test carried out on the Baltic Sea, the system was able to detect and range the active tags up to a distance of 5800 m using an illumination signal transmit-power of 100 W. Special attention is given to the development, performance, and conceptual differences between passive and active tags used in the system. Guidelines for achieving a high HR dynamic range, including a system components description, are given and a comparison with other HR systems is performed. System integration with a commercial maritime X-band navigation radar is shown to demonstrate a solution for rapid search and rescue response and quick localization.}, language = {en} } @article{MonakhovaDiehl2021, author = {Monakhova, Yulia and Diehl, Bernd W.K.}, title = {Novel approach of qNMR workflow by standardization using 2H integral: Application to any intrinsic calibration standard}, series = {Talanta}, volume = {222}, journal = {Talanta}, number = {Article number: 121504}, publisher = {Elsevier}, isbn = {0039-9140}, doi = {10.1016/j.talanta.2020.121504}, year = {2021}, abstract = {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.).}, language = {en} } @article{MonakhovaDiehl2021, author = {Monakhova, Yulia and Diehl, Bernd W. K.}, title = {A step towards optimization of the qNMR workflow: proficiency testing exercise at an GxP-accredited laboratory}, series = {Applied Magnetic Resonance}, volume = {52}, journal = {Applied Magnetic Resonance}, publisher = {Springer Nature}, address = {Wien}, issn = {1613-7507}, doi = {10.1007/s00723-021-01324-3}, pages = {581 -- 593}, year = {2021}, abstract = {Quantitative nuclear magnetic resonance (qNMR) is considered as a powerful tool for multicomponent mixture analysis as well as for the purity determination of single compounds. Special attention is currently paid to the training of operators and study directors involved in qNMR testing. To assure that only qualified personnel are used for sample preparation at our GxP-accredited laboratory, weighing test was proposed. Sixteen participants performed six-fold weighing of the binary mixture of dibutylated hydroxytoluene (BHT) and 1,2,4,5-tetrachloro-3-nitrobenzene (TCNB). To evaluate the quality of data analysis, all spectra were evaluated manually by a qNMR expert and using in-house developed automated routine. The results revealed that mean values are comparable and both evaluation approaches are free of systematic error. However, automated evaluation resulted in an approximately 20\% increase in precision. The same findings were revealed for qNMR analysis of 32 compounds used in pharmaceutical industry. Weighing test by six-fold determination in binary mixtures and automated qNMR methodology can be recommended as efficient tools for evaluating staff proficiency. The automated qNMR method significantly increases throughput and precision of qNMR for routine measurements and extends application scope of qNMR.}, language = {en} } @article{EngelmannShalabyShashaetal.2021, author = {Engelmann, Ulrich M. and Shalaby, Ahmed and Shasha, Carolyn and Krishnan, Kannan M. and Krause, Hans-Joachim}, title = {Comparative modeling of frequency mixing measurements of magnetic nanoparticles using micromagnetic simulations and Langevin theory}, series = {Nanomaterials}, volume = {11}, journal = {Nanomaterials}, number = {5}, publisher = {MDPI}, address = {Basel}, isbn = {2079-4991}, doi = {10.3390/nano11051257}, pages = {1 -- 16}, year = {2021}, abstract = {Dual frequency magnetic excitation of magnetic nanoparticles (MNP) enables enhanced biosensing applications. This was studied from an experimental and theoretical perspective: nonlinear sum-frequency components of MNP exposed to dual-frequency magnetic excitation were measured as a function of static magnetic offset field. The Langevin model in thermodynamic equilibrium was fitted to the experimental data to derive parameters of the lognormal core size distribution. These parameters were subsequently used as inputs for micromagnetic Monte-Carlo (MC)-simulations. From the hysteresis loops obtained from MC-simulations, sum-frequency components were numerically demodulated and compared with both experiment and Langevin model predictions. From the latter, we derived that approximately 90\% of the frequency mixing magnetic response signal is generated by the largest 10\% of MNP. We therefore suggest that small particles do not contribute to the frequency mixing signal, which is supported by MC-simulation results. Both theoretical approaches describe the experimental signal shapes well, but with notable differences between experiment and micromagnetic simulations. These deviations could result from Brownian relaxations which are, albeit experimentally inhibited, included in MC-simulation, or (yet unconsidered) cluster-effects of MNP, or inaccurately derived input for MC-simulations, because the largest particles dominate the experimental signal but concurrently do not fulfill the precondition of thermodynamic equilibrium required by Langevin theory.}, language = {en} } @article{SaretzkiBergmannDahmannetal.2021, author = {Saretzki, Charlotte and Bergmann, Ole and Dahmann, Peter and Janser, Frank and Keimer, Jona and Machado, Patricia and Morrison, Audry and Page, Henry and Pluta, Emil and St{\"u}bing, Felix and K{\"u}pper, Thomas}, title = {Are small airplanes safe with regards to COVID-19 transmission?}, series = {Journal of Travel Medicine}, volume = {28}, journal = {Journal of Travel Medicine}, number = {7}, publisher = {Oxford University Press}, address = {Oxford}, issn = {1708-8305}, doi = {10.1093/jtm/taab105}, year = {2021}, language = {en} } @article{KarschuckKaulenPoghossianetal.2021, author = {Karschuck, Tobias and Kaulen, Corinna and Poghossian, Arshak and Wagner, Patrick H. and Sch{\"o}ning, Michael Josef}, title = {Gold nanoparticle-modified capacitive field-effect sensors: Studying the surface density of nanoparticles and coupling of charged polyelectrolyte macromolecules}, series = {Electrochemical Science Advances}, volume = {2}, journal = {Electrochemical Science Advances}, number = {5}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {0938-5193}, doi = {10.1002/elsa.202100179}, pages = {10 Seiten}, year = {2021}, abstract = {The coupling of ligand-stabilized gold nanoparticles with field-effect devices offers new possibilities for label-free biosensing. In this work, we study the immobilization of aminooctanethiol-stabilized gold nanoparticles (AuAOTs) on the silicon dioxide surface of a capacitive field-effect sensor. The terminal amino group of the AuAOT is well suited for the functionalization with biomolecules. The attachment of the positively-charged AuAOTs on a capacitive field-effect sensor was detected by direct electrical readout using capacitance-voltage and constant capacitance measurements. With a higher particle density on the sensor surface, the measured signal change was correspondingly more pronounced. The results demonstrate the ability of capacitive field-effect sensors for the non-destructive quantitative validation of nanoparticle immobilization. In addition, the electrostatic binding of the polyanion polystyrene sulfonate to the AuAOT-modified sensor surface was studied as a model system for the label-free detection of charged macromolecules. Most likely, this approach can be transferred to the label-free detection of other charged molecules such as enzymes or antibodies.}, language = {en} } @article{HacklBuessKammerlohretal.2021, author = {Hackl, Michael and Buess, Eduard and Kammerlohr, Sandra and Nacov, Julia and Staat, Manfred and Leschinger, Tim and M{\"u}ller, Lars P. and Wegmann, Kilian}, title = {A "comma sign"-directed subscapularis repair in anterosuperior rotator cuff tears yields biomechanical advantages in a cadaveric model}, series = {The american journal of sports medicine}, volume = {49}, journal = {The american journal of sports medicine}, number = {12}, publisher = {Sage}, address = {London}, issn = {1552-3365}, doi = {10.1177/03635465211031506}, pages = {3212 -- 3217}, year = {2021}, abstract = {Background: Additional stabilization of the "comma sign" in anterosuperior rotator cuff repair has been proposed to provide biomechanical benefits regarding stability of the repair. Purpose: This in vitro investigation aimed to investigate the influence of a comma sign-directed reconstruction technique for anterosuperior rotator cuff tears on the primary stability of the subscapularis tendon repair. Study Design: Controlled laboratory study. Methods: A total of 18 fresh-frozen cadaveric shoulders were used in this study. Anterosuperior rotator cuff tears (complete full-thickness tear of the supraspinatus and subscapularis tendons) were created, and supraspinatus repair was performed with a standard suture bridge technique. The subscapularis was repaired with either a (1) single-row or (2) comma sign technique. A high-resolution 3D camera system was used to analyze 3-mm and 5-mm gap formation at the subscapularis tendon-bone interface upon incremental cyclic loading. Moreover, the ultimate failure load of the repair was recorded. A Mann-Whitney test was used to assess significant differences between the 2 groups. Results: The comma sign repair withstood significantly more loading cycles than the single-row repair until 3-mm and 5-mm gap formation occurred (P≤ .047). The ultimate failure load did not reveal any significant differences when the 2 techniques were compared (P = .596). Conclusion: The results of this study show that additional stabilization of the comma sign enhanced the primary stability of subscapularis tendon repair in anterosuperior rotator cuff tears. Although this stabilization did not seem to influence the ultimate failure load, it effectively decreased the micromotion at the tendon-bone interface during cyclic loading. Clinical Relevance: The proposed technique for stabilization of the comma sign has shown superior biomechanical properties in comparison with a single-row repair and might thus improve tendon healing. Further clinical research will be necessary to determine its influence on the functional outcome.}, language = {en} } @article{BiewendtBlaschkeBoehnert2021, author = {Biewendt, Marcel and Blaschke, Florian and B{\"o}hnert, Arno}, title = {Motivational factors in organisational change}, series = {SocioEconomic Challenges}, volume = {5}, journal = {SocioEconomic Challenges}, number = {3}, publisher = {ARMG}, address = {Sumy}, issn = {2520-6214}, doi = {10.21272/sec.5(3).15-27.2021}, pages = {15 -- 27}, year = {2021}, abstract = {The presented paper gives an overview of the most important and most common theories and concepts from the economic field of organisational change and is also enriched with quantitative publication data, which underlines the relevance of the topic. In particular, the topic presented is interwoven in an interdisciplinary way with economic psychological models, which are underpinned within the models with content from leading scholars in the field. The pace of change in companies is accelerating, as is technological change in our society. Adaptations of the corporate structure, but also of management techniques and tasks, are therefore indispensable. This includes not only the right approaches to employee motivation, but also the correct use of intrinsic and extrinsic motivational factors. Based on the hypothesis put forward by the scientist and researcher Rollinson in his book "Organisational behaviour and analysis" that managers believe motivational resources are available at all times, socio-economic and economic psychological theories are contrasted here in order to critically examine this statement. In addition, a fictitious company was created as a model for this work in order to illustrate the effects of motivational deficits in practice. In this context, the theories presented are applied to concrete problems within the model and conclusions are drawn about their influence and applicability. This led to the conclusion that motivation is a very individual challenge for each employee, which requires adapted and personalised approaches. On the other hand, the recommendations for action for supervisors in the case of motivation deficits also cannot be answered in a blanket manner, but can only be solved with the help of professional, expert-supported processing due to the economic-psychological realities of motivation. Identifying, analysing and remedying individual employee motivation deficits is, according to the authors, a problem and a challenge of great importance, especially in the context of rapidly changing ecosystems in modern companies, as motivation also influences other factors such as individual productivity. The authors therefore conclude that good motivation through the individual and customised promotion and further training of employees is an important point for achieving important corporate goals in order to remain competitive on the one hand and to create a productive and pleasant working environment on the other.}, language = {en} } @article{Gaigall2021, author = {Gaigall, Daniel}, title = {Test for Changes in the Modeled Solvency Capital Requirement of an Internal Risk Model}, series = {ASTIN Bulletin}, volume = {51}, journal = {ASTIN Bulletin}, number = {3}, publisher = {Cambridge Univ. Press}, address = {Cambridge}, issn = {1783-1350}, doi = {10.1017/asb.2021.20}, pages = {813 -- 837}, year = {2021}, abstract = {In the context of the Solvency II directive, the operation of an internal risk model is a possible way for risk assessment and for the determination of the solvency capital requirement of an insurance company in the European Union. A Monte Carlo procedure is customary to generate a model output. To be compliant with the directive, validation of the internal risk model is conducted on the basis of the model output. For this purpose, we suggest a new test for checking whether there is a significant change in the modeled solvency capital requirement. Asymptotic properties of the test statistic are investigated and a bootstrap approximation is justified. A simulation study investigates the performance of the test in the finite sample case and confirms the theoretical results. The internal risk model and the application of the test is illustrated in a simplified example. The method has more general usage for inference of a broad class of law-invariant and coherent risk measures on the basis of a paired sample.}, language = {en} } @article{PoghossianWeldenBuniatyanetal.2021, author = {Poghossian, Arshak and Welden, Rene and Buniatyan, Vahe V. and Sch{\"o}ning, Michael Josef}, title = {An Array of On-Chip Integrated, Individually Addressable Capacitive Field-Effect Sensors with Control Gate: Design and Modelling}, series = {Sensors}, volume = {21}, journal = {Sensors}, number = {18}, publisher = {MDPI}, address = {Basel}, issn = {1424-8220}, doi = {10.3390/s21186161}, pages = {17}, year = {2021}, abstract = {The on-chip integration of multiple biochemical sensors based on field-effect electrolyte-insulator-semiconductor capacitors (EISCAP) is challenging due to technological difficulties in realization of electrically isolated EISCAPs on the same Si chip. In this work, we present a new simple design for an array of on-chip integrated, individually electrically addressable EISCAPs with an additional control gate (CG-EISCAP). The existence of the CG enables an addressable activation or deactivation of on-chip integrated individual CG-EISCAPs by simple electrical switching the CG of each sensor in various setups, and makes the new design capable for multianalyte detection without cross-talk effects between the sensors in the array. The new designed CG-EISCAP chip was modelled in so-called floating/short-circuited and floating/capacitively-coupled setups, and the corresponding electrical equivalent circuits were developed. In addition, the capacitance-voltage curves of the CG-EISCAP chip in different setups were simulated and compared with that of a single EISCAP sensor. Moreover, the sensitivity of the CG-EISCAP chip to surface potential changes induced by biochemical reactions was simulated and an impact of different parameters, such as gate voltage, insulator thickness and doping concentration in Si, on the sensitivity has been discussed.}, language = {en} } @article{GorzalkaSchmiedtSchorn2021, author = {Gorzalka, Philip and Schmiedt, Jacob Estevam and Schorn, Christian}, title = {Automated Generation of an Energy Simulation Model for an Existing Building from UAV Imagery}, series = {Buildings}, volume = {11}, journal = {Buildings}, number = {9}, publisher = {MDPI}, address = {Basel}, issn = {2075-5309}, doi = {10.3390/buildings11090380}, pages = {15 Seiten}, year = {2021}, abstract = {An approach to automatically generate a dynamic energy simulation model in Modelica for a single existing building is presented. It aims at collecting data about the status quo in the preparation of energy retrofits with low effort and costs. The proposed method starts from a polygon model of the outer building envelope obtained from photogrammetrically generated point clouds. The open-source tools TEASER and AixLib are used for data enrichment and model generation. A case study was conducted on a single-family house. The resulting model can accurately reproduce the internal air temperatures during synthetical heating up and cooling down. Modelled and measured whole building heat transfer coefficients (HTC) agree within a 12\% range. A sensitivity analysis emphasises the importance of accurate window characterisations and justifies the use of a very simplified interior geometry. Uncertainties arising from the use of archetype U-values are estimated by comparing different typologies, with best- and worst-case estimates showing differences in pre-retrofit heat demand of about ±20\% to the average; however, as the assumptions made are permitted by some national standards, the method is already close to practical applicability and opens up a path to quickly estimate possible financial and energy savings after refurbishment.}, language = {en} } @article{BiewendtBlaschkeBoehnert2021, author = {Biewendt, Marcel and Blaschke, Florian and B{\"o}hnert, Arno}, title = {A review of contemporary challenges in business culture}, series = {International Journal of Applied Research in Business and Management}, volume = {2}, journal = {International Journal of Applied Research in Business and Management}, number = {1}, publisher = {Wohllebe \& Ross Publishing}, address = {Hamburg}, issn = {2700-8983}, doi = {10.51137/ijarbm.2021.2.1.1}, pages = {1 -- 12}, year = {2021}, abstract = {The following article deals with the basic principles of intercultural management and possible improvements in terms of cultural, ethnic and gender diversification. The results are exemplarily applied to a bank located in Germany. The aim of this paper is to find out to what extent intercultural management could improve the productivity of Relatos-Bank in dealing with foreign employees or employees with a different cultural background. To achieve this goal, the authors con-duct a literature research. The main sources of information are books, journal articles and internet sources. It becomes clear that especially the different perceptions of different generations have a potential for conflict, which can be counteracted by applying presented scientific models. Equalizing the salaries of female and male employees and equalizing the rights and distribution of power could also be the key to becoming an open-minded, dynamic and fair organization that is pre-pared for the rapidly changing environment in which it operates.}, language = {en} } @article{HeuermannHarzheimCronenbroeck2021, author = {Heuermann, Holger and Harzheim, Thomas and Cronenbroeck, Tobias}, title = {First SIMO harmonic radar based on the SFCW concept and the HR transfer function}, series = {Remote sensing}, volume = {13}, journal = {Remote sensing}, number = {24}, publisher = {MDPI}, address = {Basel}, issn = {2072-4292}, doi = {10.3390/rs13245088}, pages = {23 Seiten}, year = {2021}, abstract = {This paper presents a new SIMO radar system based on a harmonic radar (HR) stepped frequency continuous wave (SFCW) architecture. Simple tags that can be electronically individually activated and deactivated via a DC control voltage were developed and combined to form an MO array field. This HR operates in the entire 2.45 GHz ISM band for transmitting the illumination signal and receives at twice the stimulus frequency and bandwidth centered around 4.9 GHz. This paper presents the development, the basic theory of a HR system for the characterization of objects placed into the propagation path in-between the radar and the reflectors (similar to a free-space measurement with a network analyzer) as well as first measurements performed by the system. Further detailed measurement series will be made available later on to other researchers to develop AI and machine learning based signal processing routines or synthetic aperture radar algorithms for imaging, object recognition, and feature extraction. For this purpose, the necessary information is published in this paper. It is explained in detail why this SIMO-HR can be an attractive solution augmenting or replacing existing systems for radar measurements in production technology for material under test measurements and as a simplified MIMO system. The novel HR transfer function, which is a basis for researchers and developers for material characterization or imaging algorithms, is introduced and metrologically verified in a well traceable coaxial setup.}, language = {en} } @article{RichterBraunsteinStaeudleetal.2021, author = {Richter, Charlotte and Braunstein, Bjoern and St{\"a}udle, Benjamin and Attias, Julia and Suess, Alexander and Weber, Tobias and Mileva, Katja N. and Rittweger, Joern and Green, David A. and Albracht, Kirsten}, title = {Gastrocnemius medialis contractile behavior is preserved during 30\% body weight supported gait training}, series = {Frontiers in Sports and Active Living}, volume = {2021}, journal = {Frontiers in Sports and Active Living}, number = {2}, publisher = {Frontiers}, address = {Lausanne}, issn = {2624-9367}, doi = {10.3389/fspor.2020.614559}, pages = {Artikel 614559}, year = {2021}, abstract = {Rehabilitative body weight supported gait training aims at restoring walking function as a key element in activities of daily living. Studies demonstrated reductions in muscle and joint forces, while kinematic gait patterns appear to be preserved with up to 30\% weight support. However, the influence of body weight support on muscle architecture, with respect to fascicle and series elastic element behavior is unknown, despite this having potential clinical implications for gait retraining. Eight males (31.9 ± 4.7 years) walked at 75\% of the speed at which they typically transition to running, with 0\% and 30\% body weight support on a lower-body positive pressure treadmill. Gastrocnemius medialis fascicle lengths and pennation angles were measured via ultrasonography. Additionally, joint kinematics were analyzed to determine gastrocnemius medialis muscle-tendon unit lengths, consisting of the muscle's contractile and series elastic elements. Series elastic element length was assessed using a muscle-tendon unit model. Depending on whether data were normally distributed, a paired t-test or Wilcoxon signed rank test was performed to determine if body weight supported walking had any effects on joint kinematics and fascicle-series elastic element behavior. Walking with 30\% body weight support had no statistically significant effect on joint kinematics and peak series elastic element length. Furthermore, at the time when peak series elastic element length was achieved, and on average across the entire stance phase, muscle-tendon unit length, fascicle length, pennation angle, and fascicle velocity were unchanged with respect to body weight support. In accordance with unchanged gait kinematics, preservation of fascicle-series elastic element behavior was observed during walking with 30\% body weight support, which suggests transferability of gait patterns to subsequent unsupported walking.}, language = {en} } @article{GriegerSchwabedalWendeletal.2021, author = {Grieger, Niklas and Schwabedal, Justus T. C. and Wendel, Stefanie and Ritze, Yvonne and Bialonski, Stephan}, title = {Automated scoring of pre-REM sleep in mice with deep learning}, series = {Scientific Reports}, volume = {11}, journal = {Scientific Reports}, number = {Art. 12245}, publisher = {Springer Nature}, address = {London}, issn = {2045-2322}, doi = {10.1038/s41598-021-91286-0}, year = {2021}, abstract = {Reliable automation of the labor-intensive manual task of scoring animal sleep can facilitate the analysis of long-term sleep studies. In recent years, deep-learning-based systems, which learn optimal features from the data, increased scoring accuracies for the classical sleep stages of Wake, REM, and Non-REM. Meanwhile, it has been recognized that the statistics of transitional stages such as pre-REM, found between Non-REM and REM, may hold additional insight into the physiology of sleep and are now under vivid investigation. We propose a classification system based on a simple neural network architecture that scores the classical stages as well as pre-REM sleep in mice. When restricted to the classical stages, the optimized network showed state-of-the-art classification performance with an out-of-sample F1 score of 0.95 in male C57BL/6J mice. When unrestricted, the network showed lower F1 scores on pre-REM (0.5) compared to the classical stages. The result is comparable to previous attempts to score transitional stages in other species such as transition sleep in rats or N1 sleep in humans. Nevertheless, we observed that the sequence of predictions including pre-REM typically transitioned from Non-REM to REM reflecting sleep dynamics observed by human scorers. Our findings provide further evidence for the difficulty of scoring transitional sleep stages, likely because such stages of sleep are under-represented in typical data sets or show large inter-scorer variability. We further provide our source code and an online platform to run predictions with our trained network.}, language = {en} } @article{BechtSchollmayerMonakhovaetal.2021, author = {Becht, Alexander and Schollmayer, Curd and Monakhova, Yulia and Holzgrabe, Ulrike}, title = {Tracing the origin of paracetamol tablets by near-infrared, mid-infrared, and nuclear magnetic resonance spectroscopy using principal component analysis and linear discriminant analysis}, series = {Analytical and Bioanalytical Chemistry}, volume = {413}, journal = {Analytical and Bioanalytical Chemistry}, publisher = {Springer Nature}, issn = {1618-2650}, doi = {10.1007/s00216-021-03249-z}, pages = {3107 -- 3118}, year = {2021}, abstract = {Most drugs are no longer produced in their own countries by the pharmaceutical companies, but by contract manufacturers or at manufacturing sites in countries that can produce more cheaply. This not only makes it difficult to trace them back but also leaves room for criminal organizations to fake them unnoticed. For these reasons, it is becoming increasingly difficult to determine the exact origin of drugs. The goal of this work was to investigate how exactly this is possible by using different spectroscopic methods like nuclear magnetic resonance and near- and mid-infrared spectroscopy in combination with multivariate data analysis. As an example, 56 out of 64 different paracetamol preparations, collected from 19 countries around the world, were chosen to investigate whether it is possible to determine the pharmaceutical company, manufacturing site, or country of origin. By means of suitable pre-processing of the spectra and the different information contained in each method, principal component analysis was able to evaluate manufacturing relationships between individual companies and to differentiate between production sites or formulations. Linear discriminant analysis showed different results depending on the spectral method and purpose. For all spectroscopic methods, it was found that the classification of the preparations to their manufacturer achieves better results than the classification to their pharmaceutical company. The best results were obtained with nuclear magnetic resonance and near-infrared data, with 94.6\%/99.6\% and 98.7/100\% of the spectra of the preparations correctly assigned to their pharmaceutical company or manufacturer.}, language = {en} } @article{BergsMonakhovaDiehletal.2021, author = {Bergs, Michel and Monakhova, Yulia and Diehl, Bernd W. and Konow, Christopher and V{\"o}lkering, Georg and Pude, Ralf and Schulze, Margit}, title = {Lignins isolated via catalyst-free organosolv pulping from Miscanthus x giganteus, M. sinensis, M. robustus and M. nagara: a comparative study}, series = {Molecules}, volume = {26}, journal = {Molecules}, number = {4}, publisher = {MDPI}, address = {Basel}, issn = {1420-3049}, doi = {10.3390/molecules26040842}, year = {2021}, abstract = {As a low-input crop, Miscanthus offers numerous advantages that, in addition to agricultural applications, permits its exploitation for energy, fuel, and material production. Depending on the Miscanthus genotype, season, and harvest time as well as plant component (leaf versus stem), correlations between structure and properties of the corresponding isolated lignins differ. Here, a comparative study is presented between lignins isolated from M. x giganteus, M. sinensis, M. robustus and M. nagara using a catalyst-free organosolv pulping process. The lignins from different plant constituents are also compared regarding their similarities and differences regarding monolignol ratio and important linkages. Results showed that the plant genotype has the weakest influence on monolignol content and interunit linkages. In contrast, structural differences are more significant among lignins of different harvest time and/or season. Analyses were performed using fast and simple methods such as nuclear magnetic resonance (NMR) spectroscopy. Data was assigned to four different linkages (A: β-O-4 linkage, B: phenylcoumaran, C: resinol, D: β-unsaturated ester). In conclusion, A content is particularly high in leaf-derived lignins at just under 70\% and significantly lower in stem and mixture lignins at around 60\% and almost 65\%. The second most common linkage pattern is D in all isolated lignins, the proportion of which is also strongly dependent on the crop portion. Both stem and mixture lignins, have a relatively high share of approximately 20\% or more (maximum is M. sinensis Sin2 with over 30\%). In the leaf-derived lignins, the proportions are significantly lower on average. Stem samples should be chosen if the highest possible lignin content is desired, specifically from the M. x giganteus genotype, which revealed lignin contents up to 27\%. Due to the better frost resistance and higher stem stability, M. nagara offers some advantages compared to M. x giganteus. Miscanthus crops are shown to be very attractive lignocellulose feedstock (LCF) for second generation biorefineries and lignin generation in Europe.}, language = {en} } @article{BurgerRumpfDoetal.2021, author = {Burger, Ren{\´e} and Rumpf, Jessica and Do, Xuan Tung and Monakhova, Yulia and Diehl, Bernd W. K. and Rehahn, Matthias and Schulze, Margit}, title = {Is NMR combined with multivariate regression applicable for the molecular weight determination of randomly cross-linked polymers such as lignin?}, series = {ACS Omega}, volume = {6}, journal = {ACS Omega}, number = {44}, publisher = {ACS Publications}, address = {Washington, DC}, issn = {2470-1343}, doi = {10.1021/acsomega.1c03574}, pages = {29516 -- 29524}, year = {2021}, abstract = {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.}, language = {en} } @article{MonakhovaDiehl2021, author = {Monakhova, Yulia and Diehl, Bernd W. K.}, title = {Simplification of NMR Workflows by Standardization Using 2H Integral of Deuterated Solvent as Applied to Aloe vera Preparations}, series = {Applied Magnetic Resonance}, volume = {52}, journal = {Applied Magnetic Resonance}, number = {11}, publisher = {Springer}, address = {Cham}, issn = {1613-7507}, doi = {10.1007/s00723-021-01393-4}, pages = {1591 -- 1600}, year = {2021}, abstract = {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.).}, language = {en} } @article{BurmistrovaSobolevaMonakhova2021, author = {Burmistrova, Natalia A. and Soboleva, Polina M. and Monakhova, Yulia}, title = {Is infrared spectroscopy combined with multivariate analysis a promising tool for heparin authentication?}, series = {Journal of Pharmaceutical and Biomedical Analysis}, volume = {194}, journal = {Journal of Pharmaceutical and Biomedical Analysis}, number = {Article number: 113811}, publisher = {Elsevier}, address = {Amsterdam}, isbn = {0731-7085}, doi = {10.1016/j.jpba.2020.113811}, year = {2021}, abstract = {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.}, language = {en} } @article{PourshahidiAchtsnichtNambipareecheeetal.2021, author = {Pourshahidi, Ali Mohammad and Achtsnicht, Stefan and Nambipareechee, Mrinal Murali and Offenh{\"a}usser, Andreas and Krause, Hans-Joachim}, title = {Multiplex detection of magnetic beads using offset field dependent frequency mixing magnetic detection}, series = {Sensors}, volume = {21}, journal = {Sensors}, number = {17}, publisher = {MDPI}, address = {Basel}, issn = {1424-8220}, doi = {10.3390/s21175859}, pages = {16 Seiten}, year = {2021}, abstract = {Magnetic immunoassays employing Frequency Mixing Magnetic Detection (FMMD) have recently become increasingly popular for quantitative detection of various analytes. Simultaneous analysis of a sample for two or more targets is desirable in order to reduce the sample amount, save consumables, and save time. We show that different types of magnetic beads can be distinguished according to their frequency mixing response to a two-frequency magnetic excitation at different static magnetic offset fields. We recorded the offset field dependent FMMD response of two different particle types at frequencies ƒ₁ + n⋅ƒ₂, n = 1, 2, 3, 4 with ƒ₁ = 30.8 kHz and ƒ₂ = 63 Hz. Their signals were clearly distinguishable by the locations of the extremes and zeros of their responses. Binary mixtures of the two particle types were prepared with different mixing ratios. The mixture samples were analyzed by determining the best linear combination of the two pure constituents that best resembled the measured signals of the mixtures. Using a quadratic programming algorithm, the mixing ratios could be determined with an accuracy of greater than 14\%. If each particle type is functionalized with a different antibody, multiplex detection of two different analytes becomes feasible.}, language = {en} } @article{Staat2021, author = {Staat, Manfred}, title = {An extension strain type Mohr-Coulomb criterion}, series = {Rock mechanics and rock engineering}, volume = {54}, journal = {Rock mechanics and rock engineering}, number = {12}, publisher = {Springer Nature}, address = {Cham}, issn = {1434-453X}, doi = {10.1007/s00603-021-02608-7}, pages = {6207 -- 6233}, year = {2021}, abstract = {Extension fractures are typical for the deformation under low or no confining pressure. They can be explained by a phenomenological extension strain failure criterion. In the past, a simple empirical criterion for fracture initiation in brittle rock has been developed. In this article, it is shown that the simple extension strain criterion makes unrealistic strength predictions in biaxial compression and tension. To overcome this major limitation, a new extension strain criterion is proposed by adding a weighted principal shear component to the simple criterion. The shear weight is chosen, such that the enriched extension strain criterion represents the same failure surface as the Mohr-Coulomb (MC) criterion. Thus, the MC criterion has been derived as an extension strain criterion predicting extension failure modes, which are unexpected in the classical understanding of the failure of cohesive-frictional materials. In progressive damage of rock, the most likely fracture direction is orthogonal to the maximum extension strain leading to dilatancy. The enriched extension strain criterion is proposed as a threshold surface for crack initiation CI and crack damage CD and as a failure surface at peak stress CP. Different from compressive loading, tensile loading requires only a limited number of critical cracks to cause failure. Therefore, for tensile stresses, the failure criteria must be modified somehow, possibly by a cut-off corresponding to the CI stress. Examples show that the enriched extension strain criterion predicts much lower volumes of damaged rock mass compared to the simple extension strain criterion.}, language = {en} } @article{WeldenJablonskiWegeetal.2021, author = {Welden, Rene and Jablonski, Melanie and Wege, Christina and Keusgen, Michael and Wagner, Patrick Hermann and Wagner, Torsten and Sch{\"o}ning, Michael Josef}, title = {Light-Addressable Actuator-Sensor Platform for Monitoring and Manipulation of pH Gradients in Microfluidics: A Case Study with the Enzyme Penicillinase}, series = {Biosensors}, volume = {11}, journal = {Biosensors}, number = {6}, publisher = {MDPI}, address = {Basel}, issn = {2079-6374}, doi = {10.3390/bios11060171}, pages = {Artikel 171}, year = {2021}, abstract = {The feasibility of light-addressed detection and manipulation of pH gradients inside an electrochemical microfluidic cell was studied. Local pH changes, induced by a light-addressable electrode (LAE), were detected using a light-addressable potentiometric sensor (LAPS) with different measurement modes representing an actuator-sensor system. Biosensor functionality was examined depending on locally induced pH gradients with the help of the model enzyme penicillinase, which had been immobilized in the microfluidic channel. The surface morphology of the LAE and enzyme-functionalized LAPS was studied by scanning electron microscopy. Furthermore, the penicillin sensitivity of the LAPS inside the microfluidic channel was determined with regard to the analyte's pH influence on the enzymatic reaction rate. In a final experiment, the LAE-controlled pH inhibition of the enzyme activity was monitored by the LAPS.}, language = {en} } @article{AkimbekovDigelTastambeketal.2021, author = {Akimbekov, Nuraly S. and Digel, Ilya and Tastambek, Kuanysh T. and Sherelkhan, Dinara K. and Jussupova, Dariya B. and Altynbay, Nazym P.}, title = {Low-rank coal as a source of humic substances for soil amendment and fertility management}, series = {Agriculture}, volume = {11}, journal = {Agriculture}, number = {12}, publisher = {MDPI}, address = {Basel}, issn = {2077-0472}, doi = {10.3390/agriculture11121261}, pages = {25 Seiten}, year = {2021}, abstract = {Humic substances (HS), as important environmental components, are essential to soil health and agricultural sustainability. The usage of low-rank coal (LRC) for energy generation has declined considerably due to the growing popularity of renewable energy sources and gas. However, their potential as soil amendment aimed to maintain soil quality and productivity deserves more recognition. LRC, a highly heterogeneous material in nature, contains large quantities of HS and may effectively help to restore the physicochemical, biological, and ecological functionality of soil. Multiple emerging studies support the view that LRC and its derivatives can positively impact the soil microclimate, nutrient status, and organic matter turnover. Moreover, the phytotoxic effects of some pollutants can be reduced by subsequent LRC application. Broad geographical availability, relatively low cost, and good technical applicability of LRC offer the advantage of easy fulfilling soil amendment and conditioner requirements worldwide. This review analyzes and emphasizes the potential of LRC and its numerous forms/combinations for soil amelioration and crop production. A great benefit would be a systematic investment strategy implicating safe utilization and long-term application of LRC for sustainable agricultural production.}, language = {en} } @article{Kleefeld2021, author = {Kleefeld, Andreas}, title = {The hot spots conjecture can be false: some numerical examples}, series = {Advances in Computational Mathematics}, volume = {47}, journal = {Advances in Computational Mathematics}, publisher = {Springer}, address = {Dordrecht}, issn = {1019-7168}, doi = {10.1007/s10444-021-09911-5}, year = {2021}, abstract = {The hot spots conjecture is only known to be true for special geometries. This paper shows numerically that the hot spots conjecture can fail to be true for easy to construct bounded domains with one hole. The underlying eigenvalue problem for the Laplace equation with Neumann boundary condition is solved with boundary integral equations yielding a non-linear eigenvalue problem. Its discretization via the boundary element collocation method in combination with the algorithm by Beyn yields highly accurate results both for the first non-zero eigenvalue and its corresponding eigenfunction which is due to superconvergence. Additionally, it can be shown numerically that the ratio between the maximal/minimal value inside the domain and its maximal/minimal value on the boundary can be larger than 1 + 10- 3. Finally, numerical examples for easy to construct domains with up to five holes are provided which fail the hot spots conjecture as well.}, language = {en} }