TY - JOUR A1 - Nehr, Sascha A1 - Baus, Lukas A1 - Çinar, Hasan A1 - Elsen, Ingo A1 - Frauenrath, Tobias T1 - Indoor environmental quality assessment in passively ventilated classrooms in Germany and estimation of ventilation energy losses JF - Journal of Building Engineering N2 - In this field study we present an approach for the comprehensive and room-specific assessment of parameters with the overall aim to realize energy-efficient provision of hygienically harmless and thermally comfortable indoor environmental quality in naturally ventilated non-residential buildings. The approach is based on (i) conformity assessment of room design parameters, (ii) empirical determination of theoretically expected occupant-specific supply air flow rates and corresponding air exchange rates, (iii) experimental determination of real occupant-specific supply air flow rates and corresponding air exchange rates, (iv) measurement of indoor environmental exposure conditions of T, RH, cCO2 , cPM2.5 and cTVOC, and (v) determination of real energy demands for the prevailing ventilation scheme. Underlying assessment criteria comprise the indoor environmental parameters of category II of EN 16798-1: Temperature T = 20 ◦C–24 ◦C, and relative humidity RH = 25 %–60 % as well as the guide values of the German Federal Environment Agency for cCO2 cPM2.5 and cTVOC of 1000 ppm, 15 μg m⁻³, and 1 mg m ⁻³, respectively. Investigation objects are six naturally ventilated classrooms of a German secondary school. Major factors influencing indoor environmental quality in these classrooms are the specific room volume per occupant and the window opening area. It is concluded that the rigorous implementation of ventilation recommendations laid down by the German Federal Environment Agency is ineffective with respect to anticipated indoor environmental parameters and inefficient with respect to ventilation energy losses on the order of about 10 kWh m⁻² a ⁻¹ to 30 kWh m⁻² a ⁻¹. KW - Indoor air quality KW - Indoor environmental quality KW - Energy-efficient ventilation KW - CO2 KW - PM2.5 Y1 - 2024 SN - 2352-7102 VL - 97 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Cheilytko, Andrii A1 - Alexopoulos, Spiros A1 - Pozhuyev, Andriy A1 - Kaufhold, Oliver T1 - An analytical approach to power optimization of concentrating solar power plants with thermal storage JF - Solar N2 - This paper deals with the problem of determining the optimal capacity of concentrated solar power (CSP) plants, especially in the context of hybrid solar power plants. This work presents an innovative analytical approach to optimizing the capacity of concentrated solar plants. The proposed method is based on the use of additional non-dimensional parameters, in particular, the design factor and the solar multiple factor. This paper presents a mathematical optimization model that focuses on the capacity of concentrated solar power plants where thermal storage plays a key role in the energy source. The analytical approach provides a more complete understanding of the design process for hybrid power plants. In addition, the use of additional factors and the combination of the proposed method with existing numerical methods allows for more refined optimization, which allows for the more accurate selection of the capacity for specific geographical conditions. Importantly, the proposed method significantly increases the speed of computation compared to that of traditional numerical methods. Finally, the authors present the results of the analysis of the proposed system of equations for calculating the levelized cost of electricity (LCOE) for hybrid solar power plants. The nonlinearity of the LCOE on the main calculation parameters is shown KW - analytical approach KW - optimization model KW - solar multiple factor KW - design factor KW - hybrid solar power plants KW - thermal storage KW - concentrated solar power Y1 - 2024 U6 - https://doi.org/10.3390/solar4030024 SN - 2673-9941 VL - 4 IS - 3 SP - 509 EP - 525 PB - MDPI CY - Basel ER - TY - JOUR A1 - Böhnisch, Nils A1 - Braun, Carsten A1 - Marzocca, Pierre A1 - Muscarello, Vincenzo T1 - Impact of aerodynamic interactions on aeroelastic stability of wing-propeller systems JF - Applied Sciences N2 - This paper presents initial findings from aeroelastic studies conducted on a wing-propeller model, aimed at evaluating the impact of aerodynamic interactions on wing flutter mechanisms and overall aeroelastic performance. The flutter onset is assessed using a frequency-domain method. Mid-fidelity tools based on the time-domain approach are then exploited to account for the complex aerodynamic interaction between the propeller and the wing. Specifically, the open-source software DUST and MBDyn are leveraged for this purpose. The investigation covers both windmilling and thrusting conditions. During the trim process, adjustments to the collective pitch of the blades are made to ensure consistency across operational points. Time histories are then analyzed to pinpoint flutter onset, and corresponding frequencies and damping ratios are identified. The results reveal a marginal destabilizing effect of aerodynamic interaction on flutter speed, approximately 5%. Notably, the thrusting condition demonstrates a greater destabilizing influence compared to the windmilling case. These comprehensive findings enhance the understanding of the aerodynamic behavior of such systems and offer valuable insights for early design predictions and the development of streamlined models for future endeavors. Y1 - 2024 U6 - https://doi.org/10.3390/app14198709 SN - 2076-3417 N1 - This article belongs to the Special Issue "Advances in Unsteady Aerodynamics and Aeroelasticity" VL - 14 IS - 19 PB - MDPI CY - Basel ER - TY - JOUR A1 - Tix, Julian A1 - Gotthardt, Leon A1 - Bode, Joshua A1 - Karabacak, Burak A1 - Nordmann, Janne A1 - Hengsbach, Jan-Niklas A1 - Ulber, Roland A1 - Tippkötter, Nils T1 - Enhancement of succinic acid production by Actinobacillus succinogenes in an electro-bioreactor JF - Fermentation N2 - This work examines the electrochemically enhanced production of succinic acid using the bacterium Actinobacillus succinogenes. The principal objective is to enhance the metabolic potential of glucose and CO2 utilization via the C4 pathway in order to synthesize succinic acid. We report on the development of an electro-bioreactor system to increase succinic acid production in a power-2-X approach. The use of activated carbon fibers as electrode surfaces and contact areas allows A. succinogenes to self-initiate biofilm formation. The integration of an electrical potential into the system shifts the redox balance from NAD+ to NADH, increasing the efficiency of metabolic processes. Mediators such as neutral red facilitate electron transfer within the system and optimize the redox reactions that are crucial for increased succinic acid production. Furthermore, the role of carbon nanotubes (CNTs) in electron transfer was investigated. The electro-bioreactor system developed here was operated in batch mode for 48 h and showed improvements in succinic acid yield and concentration. In particular, a run with 100 µM neutral red and a voltage of −600 mV achieved a yield of 0.7 gsuccinate·gglucose−1. In the absence of neutral red, a higher yield of 0.72 gsuccinate·gglucose−1 was achieved, which represents an increase of 14% compared to the control. When a potential of −600 mV was used in conjunction with 500 µg∙L−1 CNTs, a 21% increase in succinate concentration was observed after 48 h. An increase of 33% was achieved in the same batch by increasing the stirring speed. These results underscore the potential of the electro-bioreactor system to markedly enhance succinic acid production. KW - A. succinogenes KW - power-to-X KW - electrofermentation KW - electro-bioreactor KW - succinate Y1 - 2024 U6 - https://doi.org/10.3390/fermentation10100504 SN - 2311-5637 N1 - Corresponding author: Nils Tippkötter N1 - This article belongs to the Special Issue "Advance in Microbial Electrochemical Technologies" VL - 10 IS - 10 PB - MDPI CY - Basel ER - TY - JOUR A1 - Gong, Jing A1 - Raut, Amod A1 - Pelzer, Marcel A1 - Hüning, Felix T1 - Marking-based perpendicular parking slot detection algorithm using LiDAR sensors JF - Vehicles N2 - The emergence of automotive-grade LiDARs has given rise to new potential methods to develop novel advanced driver assistance systems (ADAS). However, accurate and reliable parking slot detection (PSD) remains a challenge, especially in the low-light conditions typical of indoor car parks. Existing camera-based approaches struggle with these conditions and require sensor fusion to determine parking slot occupancy. This paper proposes a parking slot detection (PSD) algorithm which utilizes the intensity of a LiDAR point cloud to detect the markings of perpendicular parking slots. LiDAR-based approaches offer robustness in low-light environments and can directly determine occupancy status using 3D information. The proposed PSD algorithm first segments the ground plane from the LiDAR point cloud and detects the main axis along the driving direction using a random sample consensus algorithm (RANSAC). The remaining ground point cloud is filtered by a dynamic Otsu’s threshold, and the markings of parking slots are detected in multiple windows along the driving direction separately. Hypotheses of parking slots are generated between the markings, which are cross-checked with a non-ground point cloud to determine the occupancy status. Test results showed that the proposed algorithm is robust in detecting perpendicular parking slots in well-marked car parks with high precision, low width error, and low variance. The proposed algorithm is designed in such a way that future adoption for parallel parking slots and combination with free-space-based detection approaches is possible. This solution addresses the limitations of camera-based systems and enhances PSD accuracy and reliability in challenging lighting conditions. KW - point cloud processing KW - RANSAC KW - line detection KW - automated parking KW - LiDAR KW - parking slot detection Y1 - 2024 U6 - https://doi.org/10.3390/vehicles6040083 SN - 2624-8921 N1 - Corresponding author: Felix Hüning VL - 6 IS - 4 SP - 1717 EP - 1729 PB - MDPI CY - Basel ER - TY - JOUR A1 - Luft, Angela A1 - Balc, Nicolae A1 - Bremen, Sebastian T1 - Experts' perspectives on the adoption of additive manufacturing in the industry and its interrelated implications in production structures JF - Acta Technica Napocensis N2 - Additive Manufacturing (AM) is a topic that is becoming more relevant to many companies globally. With AM's progressive development and use for series production, integrating the technology into existing production structures is becoming an important criterion for businesses. This study qualitatively examines the actual state and different perspectives on the integration of AM in production structures. Seven semi-structured interviews were conducted and analyzed. The interview partners were high-level experts in Additive Manufacturing and production systems from industry and science. Four main themes were identified. Key findings are the far-reaching interrelationships and implications of AM within production structures. Specific AM-related aspects were identified. Those can be used to increase the knowledge and practical application of the technology in the industry and as a foundation for economic considerations. KW - AM implementation KW - thematic analysis KW - interviews KW - manufacturing management KW - production systems KW - Additive manufacturing Y1 - 2024 SN - 1221-5872 VL - 67 IS - 1s SP - 159 EP - 168 PB - Technical University of Cluj-Napoca CY - Cluj-Napoca ER - TY - JOUR A1 - Luft, Nils A1 - Arntz, Kristian T1 - The impact and challenges of Industry 4.0 on factory design, organization and management JF - Acta Technica Napocensis N2 - The fourth industrial revolution is on its way to reshape manufacturing and value creation in a profound way. The underlying technologies like cyber-physical systems (CPS), big data, collaborative robotics, additive manufacturing or artificial intelligence offer huge potentials for the optimization and evolution of production systems. However, many manufacturing companies struggle to implement these technologies. This can only in part be attributed to the lack of skilled personal within these companies or a missing digitalization strategy. Rather, there is a fundamental incompatibility between the way current production systems and companies (Industry 3.0) are structured across multiple dimensions compared to what is necessary for industry 4.0. This is especially true in manufacturing systems and their transition towards flexible, decentralized and autonomous value creation networks. This paper shows across various dimensions these incompatibilities within manufacturing systems, explores their reasons and discusses a different approach to create a foundation for Industry 4.0 in manufacturing companies. KW - Manufacturing Process Chains KW - Tool Making KW - Operational Control KW - Technology Planning KW - Factory Planning KW - Industry 4.0 Y1 - 2024 SN - 1221-5872 VL - 67 IS - 1s SP - 151 EP - 158 PB - Technical University of Cluj-Napoca CY - Cluj-Napoca ER - TY - JOUR A1 - Abbas, Karim A1 - Balc, Nicolae A1 - Bremen, Sebastian A1 - Hedwig, Lukas T1 - Polyetheretherketone (PEEK) in rapid tooling: advancements and applications for fused filament fabrication of rubber molds JF - Acta Technica Napocensis N2 - Establishing high-performance polymers in additive manufacturing opens up new industrial applications. Polyetheretherketone (PEEK) was initially used in aerospace but is now widely applied in automotive, electronics, and medical industries. This study focuses on developing applications using PEEK and Fused Filament Fabrication for cost-efficient vulcanization injection mold production. A proof of concept confirms PEEK’s suitability for AM mold making, withstanding vulcanization conditions. Printing PEEK above its glass transition temperature of 145 °C is preferable due to its narrow process window. A new process strategy at room temperature is discussed, with micrographs showing improved inter-layer bonding at 410°C nozzle temperature and 0.1 mm layer thickness. Minimizing the layer thickness from 0.15 mm to 0.1 mm improves tensile strength by 16%. KW - Process Parameters KW - Rapid Tooling KW - Polyetheretherketone (PEEK) KW - Tensile Strength KW - Fused Filament Fabrication KW - Additive Manufacturing Y1 - 2024 SN - 1221-5872 VL - 67 IS - 1s SP - 13 EP - 22 PB - Technical University of Cluj-Napoca CY - Cluj-Napoca ER - TY - JOUR A1 - Eichler, Fabian A1 - Balc, Nicolae A1 - Bremen, Sebastian A1 - Schleser, Markus A1 - Schwarz, Alexander T1 - Research on reducing residual stresses of SLM parts made for downstream welding process JF - Acta Technica Napocensis N2 - In the face of the current trend towards larger and more complex production tasks in the SLM process and the current limitations in terms of maximum build space, the welding of SLM components to each other or to conventionally manufactured parts is becoming increasingly relevant. The fusion welding of SLM components made of 316L has so far been rarely investigated and if so, then for highly specialised laser welding processes. When welding with industrial gas welding processes such as MIG/MAG or TIG welding, distortions occur which are associated with the resulting residual stresses in the components. This paper investigates process-side influencing factors to avoid resulting residual stresses in SLM components made of 316L. The aim is to develop a strategy to build up SLM components as stress-free as possible in order to join them as profitably as possible with a downstream welding process. For this purpose, influencing parameters such as laser power, scan speed, but also scan vector length and different scan patterns are investigated with regard to their influence on residual stresses. KW - Residual Stresses KW - Hybrid Manufacturing KW - Welding KW - SLM KW - LPBF KW - Additive Manufacturing Y1 - 2024 SN - 1221-5872 VL - 67 IS - 1s SP - 69 EP - 78 PB - Technical University of Cluj-Napoca CY - Cluj-Napoca ER - TY - JOUR A1 - Valero, Daniel A1 - Felder, Stefan A1 - Kramer, Matthias A1 - Wang, Hang A1 - Carrillo, José M. A1 - Pfister, Michael A1 - Bung, Daniel Bernhard T1 - Air–water flows JF - Journal of Hydraulic Research N2 - High Froude-number open-channel flows can entrain significant volumes of air, a phenomenon that occurs continuously in spillways, in free-falling jets and in hydraulic jumps, or as localized events, notably at the toe of hydraulic jumps or in plunging jets. Within these flows, turbulence generates millions of bubbles and droplets as well as highly distorted wavy air–water interfaces. This phenomenon is crucial from a design perspective, as it influences the behaviour of high-velocity flows, potentially impairing the safety of dam operations. This review examines recent scientific and engineering progress, highlighting foundational studies and emerging developments. Notable advances have been achieved in the past decades through improved sampling of flows and the development of physics-based models. Current challenges are also identified for instrumentation, numerical modelling and (up)scaling that hinder the formulation of fundamental theories, which are instrumental for improving predictive models, able to offer robust support for the design of large hydraulic structures at prototype scale. Y1 - 2024 U6 - https://doi.org/10.1080/00221686.2024.2379482 SN - 0022-1686 (Print) SN - 1814-2079 (Online) VL - 62 IS - 4 SP - 319 EP - 339 PB - Taylor & Francis ER - TY - JOUR A1 - Myburgh-Jacobsz, Catharina Elizabeth A1 - Botha-Le Roux, Shani A1 - Kotliar, Konstantin A1 - Wentzel, Annemarie A1 - Jacobs, Adriaan A1 - De Boever, Patrick A1 - Goswami, Nandu A1 - Strijdom, Hans A1 - Smith, Wayne T1 - Retinal vessel functional responses in South Africans living with and without HIV: the EndoAfrica-NWU study JF - Microcirculation Y1 - 2024 U6 - https://doi.org/10.1111/micc.12878 SN - 1073-9688 (Print) SN - 1549-8719 (Online) IS - Early View PB - Wiley CY - Malden, MA ER - TY - JOUR A1 - Freyer, Nils A1 - Kempt, Hendrik A1 - Klöser, Lars T1 - Easy-read and large language models: on the ethical dimensions of LLM-based text simplification JF - Ethics and Information Technology N2 - The production of easy-read and plain language is a challenging task, requiring well-educated experts to write context-dependent simplifications of texts. Therefore, the domain of easy-read and plain language is currently restricted to the bare minimum of necessary information. Thus, even though there is a tendency to broaden the domain of easy-read and plain language, the inaccessibility of a significant amount of textual information excludes the target audience from partaking or entertainment and restricts their ability to live life autonomously. Large language models can solve a vast variety of natural language tasks, including the simplification of standard language texts to easy-read or plain language. Moreover, with the rise of generative models like GPT, easy-read and plain language may be applicable to all kinds of natural language texts, making formerly inaccessible information accessible to marginalized groups like, a.o., non-native speakers, and people with mental disabilities. In this paper, we argue for the feasibility of text simplification and generation in that context, outline the ethical dimensions, and discuss the implications for researchers in the field of ethics and computer science. KW - Large language models KW - Easy read KW - AI ethics KW - Natural language processing KW - Accessibility Y1 - 2024 U6 - https://doi.org/10.1007/s10676-024-09792-4 SN - 1388-1957 (Print) SN - 1572-8439 (Online) VL - 26 PB - Springer CY - Dortrecht ER - TY - JOUR A1 - Akimbekov, Nuraly A1 - Digel, Ilya A1 - Zhubanova, Azhar A1 - Tastambek, Kuanysh T. A1 - Tepecik, Atakan A1 - Sherelkhan, Dinara T1 - Biotechnological potentials of surfactants in coal utilization: a review JF - Environmental Science and Pollution Research N2 - The quest for scientifically advanced and sustainable solutions is driven by growing environmental and economic issues associated with coal mining, processing, and utilization. Consequently, within the coal industry, there is a growing recognition of the potential of microbial applications in fostering innovative technologies. Microbial-based coal solubilization, coal beneficiation, and coal dust suppression are green alternatives to traditional thermochemical and leaching technologies and better meet the need for ecologically sound and economically viable choices. Surfactant-mediated approaches have emerged as powerful tools for modeling, simulation, and optimization of coal-microbial systems and continue to gain prominence in clean coal fuel production, particularly in microbiological co-processing, conversion, and beneficiation. Surfactants (surface-active agents) are amphiphilic compounds that can reduce surface tension and enhance the solubility of hydrophobic molecules. A wide range of surfactant properties can be achieved by either directly influencing microbial growth factors, stimulants, and substrates or indirectly serving as frothers, collectors, and modifiers in the processing and utilization of coal. This review highlights the significant biotechnological potential of surfactants by providing a thorough overview of their involvement in coal biodegradation, bioprocessing, and biobeneficiation, acknowledging their importance as crucial steps in coal consumption. KW - Coal KW - Surfactants KW - Microorganisms KW - Biosolubilization KW - Biobeneficiation Y1 - 2024 U6 - https://doi.org/10.1007/s11356-024-34892-5 SN - 1614-7499 VL - 31 SP - 55099 EP - 55118 PB - Springer CY - Berlin ER - TY - JOUR A1 - Adels, Klaudia A1 - Thönnessen, Vera A1 - Monakhova, Yulia T1 - Complementary instrumental techniques applied to pain relieving tablets in an undergraduate laboratory experiment JF - Journal of Chemical Education N2 - Several unconnected laboratory experiments are usually offered for students in instrumental analysis lab. To give the students a more rational overview of the most common instrumental techniques, a new laboratory experiment was developed. Marketed pain relief drugs, familiar consumer products with one to three active components, namely, acetaminophen (paracetamol), acetylsalicylic acid (ASA), and caffeine, were selected. Common analytical methods were compared regarding the performance of qualitative and quantitative analysis of unknown tablets: UV–visible (UV–vis), infrared (IR), and nuclear magnetic resonance (NMR) spectroscopies, as well as high-performance liquid chromatography (HPLC). The students successfully uncovered the composition of formulations, which were divided into three difficulty categories. Students were shown that in addition to simple mixtures handled in theoretical classes, the composition of complex drug products can also be uncovered. By comparing the performance of different techniques, students deepen their understanding and compare the efficiency of analytical methods in the context of complex mixtures. The laboratory experiment can be adjusted for graduate level by including extra tasks such as method optimization, validation, and 2D spectroscopic techniques. KW - Instrumental analysis KW - Spectroscopy KW - Liquid chromatography KW - Qualitative and quantitative determination KW - Drugs Y1 - 2024 U6 - https://doi.org/10.1021/acs.jchemed.4c00681 SN - 0021-9584 (Print) SN - 1938-1328 (Online) PB - ACS ER - TY - JOUR A1 - Sanchez-Cespedes, Lina Maria A1 - Leasure, Douglas Ryan A1 - Tejedor-Garavito, Natalia A1 - Amaya Cruz, Glenn Harry A1 - Garcia Velez, Gustavo Adolfo A1 - Mendoza Beltrán, Andryu Enrique A1 - Marín-Salazar, Yenny Andrea A1 - Esch, Thomas A1 - Tatem, Andrew J. A1 - Ospina Bohórquez, Mariana Francisca T1 - Social cartography and satellite-derived building coverage for post-census population estimates in difficult-to-access regions of Colombia JF - Population studies : a Journal of Demography N2 - Effective government services rely on accurate population numbers to allocate resources. In Colombia and globally, census enumeration is challenging in remote regions and where armed conflict is occurring. During census preparations, the Colombian National Administrative Department of Statistics conducted social cartography workshops, where community representatives estimated numbers of dwellings and people throughout their regions. We repurposed this information, combining it with remotely sensed buildings data and other geospatial data. To estimate building counts and population sizes, we developed hierarchical Bayesian models, trained using nearby full-coverage census enumerations and assessed using 10-fold cross-validation. We compared models to assess the relative contributions of community knowledge, remotely sensed buildings, and their combination to model fit. The Community model was unbiased but imprecise; the Satellite model was more precise but biased; and the Combination model was best for overall accuracy. Results reaffirmed the power of remotely sensed buildings data for population estimation and highlighted the value of incorporating local knowledge. KW - modelled population estimates KW - population and housing census KW - GIS KW - remote sensing KW - Bayesian statistics Y1 - 2023 U6 - https://doi.org/10.1080/00324728.2023.2190151 SN - 1477-4747 VL - 78 IS - 1 SP - 3 EP - 20 PB - Taylor & Francis CY - London ER - TY - JOUR A1 - Varriale, Ludovica A1 - Hengsbach, Jan-Niklas A1 - Guo, Tianyi A1 - Kuka, Katrin A1 - Tippkötter, Nils A1 - Ulber, Roland T1 - Sustainable production of lactic acid using a perennial ryegrass as feedstock—a comparative study of fermentation at the bench- and reactor-scale, and ensiling JF - Sustainability N2 - Perennial ryegrass (Lolium perenne) is an underutilized lignocellulosic biomass that has several benefits such as high availability, renewability, and biomass yield. The grass press-juice obtained from the mechanical pretreatment can be used for the bio-based production of chemicals. Lactic acid is a platform chemical that has attracted consideration due to its broad area of applications. For this reason, the more sustainable production of lactic acid is expected to increase. In this work, lactic acid was produced using complex medium at the bench- and reactor scale, and the results were compared to those obtained using an optimized press-juice medium. Bench-scale fermentations were carried out in a pH-control system and lactic acid production reached approximately 21.84 ± 0.95 g/L in complex medium, and 26.61 ± 1.2 g/L in press-juice medium. In the bioreactor, the production yield was 0.91 ± 0.07 g/g, corresponding to a 1.4-fold increase with respect to the complex medium with fructose. As a comparison to the traditional ensiling process, the ensiling of whole grass fractions of different varieties harvested in summer and autumn was performed. Ensiling showed variations in lactic acid yields, with a yield up to 15.2% dry mass for the late-harvested samples, surpassing typical silage yields of 6–10% dry mass. KW - lactobacillus KW - lactic acid KW - ensiling KW - fermentation KW - perennial ryegrass KW - renewable resources KW - bio-based economy Y1 - 2024 U6 - https://doi.org/10.3390/su16188054 SN - 2071-1050 N1 - This article belongs to the Section "Environmental Sustainability and Applications" VL - 16 IS - 18 PB - MDPI CY - Basel ER - TY - JOUR A1 - Ortner, Marion A1 - Hauser, Christine A1 - Schmaderer, Christoph A1 - Muggenthaler, Claudia A1 - Hapfelmeier, Alexander A1 - Sorg, Christian A1 - Diehl-Schmid, Janine A1 - Kurz, Alexander A1 - Förstl, Hans A1 - Ikenberg, Benno A1 - Kotliar, Konstantin A1 - Holger, Poppert A1 - Grimmer, Timo T1 - Decreased vascular pulsatility in Alzheimer’s disease dementia measured by transcranial color-coded duplex sonography JF - Neuropsychiatric disease and treatment N2 - Purpose: Impaired paravascular drainage of β-Amyloid (Aβ) has been proposed as a contributing cause for sporadic Alzheimer’s disease (AD), as decreased cerebral blood vessel pulsatility and subsequently reduced propulsion in this pathway could lead to the accumulation and deposition of Aβ in the brain. Therefore, we hypothesized that there is an increased impairment in pulsatility across AD spectrum. Patients and Methods: Using transcranial color-coded duplex sonography (TCCS) the resistance and pulsatility index (RI; PI) of the middle cerebral artery (MCA) in healthy controls (HC, n=14) and patients with AD dementia (ADD, n=12) were measured. In a second step, we extended the sample by adding patients with mild cognitive impairment (MCI) stratified by the presence (MCI-AD, n=8) or absence of biomarkers (MCI-nonAD, n=8) indicative for underlying AD pathology, and compared RI and PI across the groups. To control for atherosclerosis as a confounder, we measured the arteriolar-venular-ratio of retinal vessels. Results: Left and right RI (p=0.020; p=0.027) and left PI (p=0.034) differed between HC and ADD controlled for atherosclerosis with AUCs of 0.776, 0.763, and 0.718, respectively. The RI and PI of MCI-AD tended towards ADD, of MCI-nonAD towards HC, respectively. RIs and PIs were associated with disease severity (p=0.010, p=0.023). Conclusion: Our results strengthen the hypothesis that impaired pulsatility could cause impaired amyloid clearance from the brain and thereby might contribute to the development of AD. However, further studies considering other factors possibly influencing amyloid clearance as well as larger sample sizes are needed. Y1 - 2019 U6 - https://doi.org/10.2147/NDT.S225754 SN - 1178-2021 IS - 15 SP - 3487 EP - 3499 PB - Dove Medical Press CY - Albany, Auckland ER - TY - JOUR A1 - Bandlitz, Stefan A1 - Nakhoul, Makram A1 - Kotliar, Konstantin T1 - Daily variations of corneal white-to-white diameter measured with different methods JF - Clinical and experimental optometry N2 - Purpose: A precise determination of the corneal diameter is essential for the diagnosis of various ocular diseases, cataract and refractive surgery as well as for the selection and fitting of contact lenses. The aim of this study was to investigate the agreement between two automatic and one manual method for corneal diameter determination and to evaluate possible diurnal variations in corneal diameter. Patients and Methods: Horizontal white-to-white corneal diameter of 20 volunteers was measured at three different fixed times of a day with three methods: Scheimpflug method (Pentacam HR, Oculus), placido based topography (Keratograph 5M, Oculus) and manual method using an image analysis software at a slitlamp (BQ900, Haag-Streit). Results: The two-factorial analysis of variance could not show a significant effect of the different instruments (p = 0.117), the different time points (p = 0.506) and the interaction between instrument and time point (p = 0.182). Very good repeatability (intraclass correlation coefficient ICC, quartile coefficient of dispersion QCD) was found for all three devices. However, manual slitlamp measurements showed a higher QCD than the automatic measurements with the Keratograph 5M and the Pentacam HR at all measurement times. Conclusion: The manual and automated methods used in the study to determine corneal diameter showed good agreement and repeatability. No significant diurnal variations of corneal diameter were observed during the period of time studied. Y1 - 2022 U6 - https://doi.org/10.2147/OPTO.S360651 SN - 0816-4622 IS - 14 SP - 173 EP - 181 PB - Taylor & Francis CY - London ER - TY - JOUR A1 - Knödler, Matthias A1 - Rühl, Clemens A1 - Emonts, Jessica A1 - Buyel, Johannes Felix T1 - Seasonal weather changes affect the yield and quality of recombinant proteins produced in transgenic tobacco plants in a greenhouse setting JF - Frontiers in Plant Science N2 - Transgenic plants have the potential to produce recombinant proteins on an agricultural scale, with yields of several tons per year. The cost-effectiveness of transgenic plants increases if simple cultivation facilities such as greenhouses can be used for production. In such a setting, we expressed a novel affinity ligand based on the fluorescent protein DsRed, which we used as a carrier for the linear epitope ELDKWA from the HIV-neutralizing antibody 2F5. The DsRed-2F5-epitope (DFE) fusion protein was produced in 12 consecutive batches of transgenic tobacco (Nicotiana tabacum) plants over the course of 2 years and was purified using a combination of blanching and immobilized metal-ion affinity chromatography (IMAC). The average purity after IMAC was 57 ± 26% (n = 24) in terms of total soluble protein, but the average yield of pure DFE (12 mg kg−1) showed substantial variation (± 97 mg kg−1, n = 24) which correlated with seasonal changes. Specifically, we found that temperature peaks (>28°C) and intense illuminance (>45 klx h−1) were associated with lower DFE yields after purification, reflecting the loss of the epitope-containing C-terminus in up to 90% of the product. Whereas the weather factors were of limited use to predict product yields of individual harvests conducted for each batch (spaced by 1 week), the average batch yields were well approximated by simple linear regression models using two independent variables for prediction (illuminance and plant age). Interestingly, accumulation levels determined by fluorescence analysis were not affected by weather conditions but positively correlated with plant age, suggesting that the product was still expressed at high levels, but the extreme conditions affected its stability, albeit still preserving the fluorophore function. The efficient production of intact recombinant proteins in plants may therefore require adequate climate control and shading in greenhouses or even cultivation in fully controlled indoor farms. KW - batch reproducibility KW - environmental correlation KW - fluorescent protein carrier KW - greenhouse cultivation KW - plant molecular farming Y1 - 2019 U6 - https://doi.org/10.3389/fpls.2019.01245 SN - 1664-462X (online-ressource) IS - 10 PB - Frontiers Media CY - Lausanne ER - TY - JOUR A1 - Bernau, C. R. A1 - Knödler, Matthias A1 - Emonts, Jessica A1 - Jäpel, Ronald Colin A1 - Buyel, Johannes Felix T1 - The use of predictive models to develop chromatography-based purification processes JF - Frontiers in Bioengineering and Biotechnology N2 - Chromatography is the workhorse of biopharmaceutical downstream processing because it can selectively enrich a target product while removing impurities from complex feed streams. This is achieved by exploiting differences in molecular properties, such as size, charge and hydrophobicity (alone or in different combinations). Accordingly, many parameters must be tested during process development in order to maximize product purity and recovery, including resin and ligand types, conductivity, pH, gradient profiles, and the sequence of separation operations. The number of possible experimental conditions quickly becomes unmanageable. Although the range of suitable conditions can be narrowed based on experience, the time and cost of the work remain high even when using high-throughput laboratory automation. In contrast, chromatography modeling using inexpensive, parallelized computer hardware can provide expert knowledge, predicting conditions that achieve high purity and efficient recovery. The prediction of suitable conditions in silico reduces the number of empirical tests required and provides in-depth process understanding, which is recommended by regulatory authorities. In this article, we discuss the benefits and specific challenges of chromatography modeling. We describe the experimental characterization of chromatography devices and settings prior to modeling, such as the determination of column porosity. We also consider the challenges that must be overcome when models are set up and calibrated, including the cross-validation and verification of data-driven and hybrid (combined data-driven and mechanistic) models. This review will therefore support researchers intending to establish a chromatography modeling workflow in their laboratory. KW - biopharmaceutical production process KW - Data-driven models KW - downstream processing design KW - experiment quality KW - hybrid model validation Y1 - 2022 U6 - https://doi.org/10.3389/fbioe.2022.1009102 SN - 2296-4185 (online-ressource) IS - 10 PB - Frontiers Media CY - Lausanne ER -