TY  - JOUR
A1  - Block, Simon
A1  - Viebahn, Peter
A1  - Jungbluth, Christian
T1  - Analysing direct air capture for enabling negative emissions in Germany: an assessment of the resource requirements and costs of a potential rollout in 2045
JF  - Frontiers in Climate
N2  - Direct air capture (DAC) combined with subsequent storage (DACCS) is discussed as one promising carbon dioxide removal option. The aim of this paper is to analyse and comparatively classify the resource consumption (land use, renewable energy and water) and costs of possible DAC implementation pathways for Germany. The paths are based on a selected, existing climate neutrality scenario that requires the removal of 20 Mt of carbon dioxide (CO2) per year by DACCS from 2045. The analysis focuses on the so-called “low-temperature” DAC process, which might be more advantageous for Germany than the “high-temperature” one. In four case studies, we examine potential sites in northern, central and southern Germany, thereby using the most suitable renewable energies for electricity and heat generation. We show that the deployment of DAC results in large-scale land use and high energy needs. The land use in the range of 167–353 km2 results mainly from the area required for renewable energy generation. The total electrical energy demand of 14.4 TWh per year, of which 46% is needed to operate heat pumps to supply the heat demand of the DAC process, corresponds to around 1.4% of Germany's envisaged electricity demand in 2045. 20 Mt of water are provided yearly, corresponding to 40% of the city of Cologne‘s water demand (1.1 million inhabitants). The capture of CO2 (DAC) incurs levelised costs of 125–138 EUR per tonne of CO2, whereby the provision of the required energy via photovoltaics in southern Germany represents the lowest value of the four case studies. This does not include the costs associated with balancing its volatility. Taking into account transporting the CO2 via pipeline to the port of Wilhelmshaven, followed by transporting and sequestering the CO2 in geological storage sites in the Norwegian North Sea (DACCS), the levelised costs increase to 161–176 EUR/tCO2. Due to the longer transport distances from southern and central Germany, a northern German site using wind turbines would be the most favourable.
KW  - rollout
KW  - economics
KW  - Germany
KW  - negative emissions
KW  - carbon dioxide removal
KW  - climate neutrality
KW  - DAC
KW  - direct air capture
Y1  - 2024
U6  - https://doi.org/10.3389/fclim.2024.1353939
SN  - 2624-9553
VL  - 6
PB  - Frontiers
CY  - Lausanne
ER  - 
TY  - JOUR
A1  - Bhattarai, Aroj
A1  - Staat, Manfred
T1  - Computational comparison of different textile implants to correct apical prolapse in females
JF  - Current Directions in Biomedical Engineering
N2  - Prosthetic textile implants of different shapes, sizes and polymers are used to correct the apical prolapse after hysterectomy (removal of the uterus). The selection of the implant before or during minimally invasive surgery depends on the patient’s anatomical defect, intended function after reconstruction and most importantly the surgeon’s preference. Weakness or damage of the supporting tissues during childbirth, menopause or previous pelvic surgeries may put females in higher risk of prolapse. Numerical simulations of reconstructed pelvic floor with weakened tissues and organ supported by textile product models: DynaMesh®-PRS soft, DynaMesh®-PRP soft and DynaMesh®-CESA from FEG Textiletechnik mbH, Germany are compared.
Y1  - 2018
U6  - https://doi.org/10.1515/cdbme-2018-0159
VL  - 4
IS  - 1
SP  - 661
EP  - 664
PB  - De Gruyter
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Bragard, Michael
A1  - Conrad, M.
A1  - van Hoek, H.
A1  - De Doncker, R. W.
T1  - The integrated emitter turn-off thyristor (IETO) : an innovative thyristor-based high power semiconductor device using MOS assisted turn-off
JF  - IEEE transactions on industry applications
Y1  - 2011
U6  - https://doi.org/10.1109/TIA.2011.2161432
SN  - 0093-9994
VL  - 47
IS  - 5
SP  - 2175
EP  - 2182
PB  - IEEE
CY  - New York
ER  - 
TY  - JOUR
A1  - Scheer, Nico
A1  - Mclaughlin, Lesley A.
A1  - Rode, Anja
A1  - MacLeod, Alastair Kenneth
A1  - Henderson, Colin J.
A1  - Wolf, Roland C.
T1  - Deletion of thirty murine cytochrome P450 genes results in viable mice with compromised drug metabolism
JF  - Drug Metabolism and Disposition
N2  - In humans, 75% of all drugs are metabolized by the cytochrome P450-dependent monooxygenase system. Enzymes encoded by the CYP2C, CYP2D, and CYP3A gene clusters account for ∼80% of this activity. There are profound species differences in the multiplicity of cytochrome P450 enzymes, and the use of mouse models to predict pathways of drug metabolism is further complicated by overlapping substrate specificity between enzymes from different gene families. To establish the role of the hepatic and extrahepatic P450 system in drug and foreign chemical disposition, drug efficacy, and toxicity, we created a unique mouse model in which 30 cytochrome P450 genes from the Cyp2c, Cyp2d, and Cyp3a gene clusters have been deleted. Remarkably, despite a wide range of putative important endogenous functions, Cyp2c/2d/3a KO mice were viable and fertile, demonstrating that these genes have evolved primarily as detoxification enzymes. Although there was no overt phenotype, detailed examination showed Cyp2c/2d/3a KO mice had a smaller body size (15%) and larger livers (20%). Changes in hepatic morphology and a decreased blood glucose (30%) were also noted. A five-drug cocktail of cytochrome P450 isozyme probe substrates were used to evaluate changes in drug pharmacokinetics; marked changes were observed in either the pharmacokinetics or metabolites formed from Cyp2c, Cyp2d, and Cyp3a substrates, whereas the metabolism of the Cyp1a substrate caffeine was unchanged. Thus, Cyp2c/2d/3a KO mice provide a powerful model to study the in vivo role of the P450 system in drug metabolism and efficacy, as well as in chemical toxicity.
Y1  - 2014
U6  - https://doi.org/10.1124/dmd.114.057885
SN  - 1521-009X
VL  - 42
IS  - 6
SP  - 1022
EP  - 1030
PB  - ASPET
CY  - Bethesda, Md.
ER  - 
TY  - JOUR
A1  - Kleefeld, Andreas
T1  - The hot spots conjecture can be false: some numerical examples
JF  - Advances in Computational Mathematics
N2  - 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.
KW  - Numerics
KW  - Boundary integral equations
KW  - Potential theory
KW  - Helmholtz equation
KW  - Interior Neumann eigenvalues
Y1  - 2021
U6  - https://doi.org/10.1007/s10444-021-09911-5
SN  - 1019-7168
VL  - 47
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Scheer, Nico
A1  - Henderson, Colin James
A1  - Kapelyukh, Yury
A1  - Rode, Anja
A1  - Mclaren, Aileen W.
A1  - MacLeod, Alastair Kenneth
A1  - Lin, De
A1  - Wright, Jayne
A1  - Stanley, Lesley
A1  - Wolf, C. Roland
T1  - An extensively humanised mouse model to predict pathways of drug disposition, drug/drug interactions, and to facilitate the design of clinical trials
JF  - Drug Metabolism and Disposition
Y1  - 2019
U6  - https://doi.org/10.1124/dmd.119.086397
IS  - Early view
ER  - 
TY  - JOUR
A1  - Goßmann, Matthias
A1  - Frotscher, Ralf
A1  - Linder, Peter
A1  - Bayer, Robin
A1  - Epple, U.
A1  - Staat, Manfred
A1  - Temiz Artmann, Aysegül
A1  - Artmann, Gerhard
T1  - Mechano-pharmacological characterization of cardiomyocytes derived from human induced pluripotent stem cells
JF  - Cellular physiology and biochemistry
N2  - Background/Aims: Common systems for the quantification of cellular contraction rely on animal-based models, complex experimental setups or indirect approaches. The herein presented CellDrum technology for testing mechanical tension of cellular monolayers and thin tissue constructs has the potential to scale-up mechanical testing towards medium-throughput analyses. Using hiPS-Cardiac Myocytes (hiPS-CMs) it represents a new perspective of drug testing and brings us closer to personalized drug medication. Methods: In the present study, monolayers of self-beating hiPS-CMs were grown on ultra-thin circular silicone membranes and deflect under the weight of the culture medium. Rhythmic contractions of the hiPS-CMs induced variations of the membrane deflection. The recorded contraction-relaxation-cycles were analyzed with respect to their amplitudes, durations, time integrals and frequencies. Besides unstimulated force and tensile stress, we investigated the effects of agonists and antagonists acting on Ca²⁺ channels (S-Bay K8644/verapamil) and Na⁺ channels (veratridine/lidocaine). Results: The measured data and simulations for pharmacologically unstimulated contraction resembled findings in native human heart tissue, while the pharmacological dose-response curves were highly accurate and consistent with reference data. Conclusion: We conclude that the combination of the CellDrum with hiPS-CMs offers a fast, facile and precise system for pharmacological, toxicological studies and offers new preclinical basic research potential.
KW  - Inotropic compounds
KW  - Pharmacology
KW  - Ion channels
KW  - CellDrum
KW  - Heart tissue culture
KW  - Induced pluripotent stem cells
KW  - Cardiac myocytes
Y1  - 2016
U6  - https://doi.org/10.1159/000443124
SN  - 1421-9778 (Online)
SN  - 1015-8987 (Print)
VL  - 38
IS  - 3
SP  - 1182
EP  - 1198
PB  - Karger
CY  - Basel
ER  - 
TY  - JOUR
A1  - Bertz, Morten
A1  - Molinnus, Denise
A1  - Schöning, Michael Josef
A1  - Homma, Takayuki
T1  - Real-time monitoring of H₂O₂ sterilization on individual bacillus atrophaeus spores by optical sensing with trapping Raman spectroscopy
JF  - Chemosensors
N2  - Hydrogen peroxide (H₂O₂), a strong oxidizer, is a commonly used sterilization agent employed during aseptic food processing and medical applications. To assess the sterilization efficiency with H₂O₂, bacterial spores are common microbial systems due to their remarkable robustness against a wide variety of decontamination strategies. Despite their widespread use, there is, however, only little information about the detailed time-resolved mechanism underlying the oxidative spore death by H₂O₂. In this work, we investigate chemical and morphological changes of individual Bacillus atrophaeus spores undergoing oxidative damage using optical sensing with trapping Raman microscopy in real-time. The time-resolved experiments reveal that spore death involves two distinct phases: (i) an initial phase dominated by the fast release of dipicolinic acid (DPA), a major spore biomarker, which indicates the rupture of the spore’s core; and (ii) the oxidation of the remaining spore material resulting in the subsequent fragmentation of the spores’ coat. Simultaneous observation of the spore morphology by optical microscopy corroborates these mechanisms. The dependence of the onset of DPA release and the time constant of spore fragmentation on H₂O₂ shows that the formation of reactive oxygen species from H₂O₂ is the rate-limiting factor of oxidative spore death.
KW  - DPA (dipicolinic acid)
KW  - sterilization
KW  - Bacillus atrophaeus spores
KW  - optical trapping
KW  - Raman spectroscopy
KW  - optical sensor setup
Y1  - 2023
U6  - https://doi.org/10.3390/chemosensors11080445
SN  - 2227-9040
N1  - This article belongs to the Special Issue "Biosensors and Chemical Sensors for Food and Healthcare Monitoring—Celebrating the 10th Anniversary"
VL  - 8
IS  - 11
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Thiebes, Anja Lena
A1  - Klein, Sarah
A1  - Zingsheim, Jonas
A1  - Möller, Georg H.
A1  - Gürzing, Stefanie
A1  - Reddemann, Manuel A.
A1  - Behbahani, Mehdi
A1  - Cornelissen, Christian G.
T1  - Effervescent atomizer as novel cell spray technology to decrease the gas-to-liquid ratio
JF  - pharmaceutics
N2  - Cell spraying has become a feasible application method for cell therapy and tissue engineering approaches. Different devices have been used with varying success. Often, twin-fluid atomizers are used, which require a high gas velocity for optimal aerosolization characteristics. To decrease the amount and velocity of required air, a custom-made atomizer was designed based on the effervescent principle. Different designs were evaluated regarding spray characteristics and their influence on human adipose-derived mesenchymal stromal cells. The arithmetic mean diameters of the droplets were 15.4–33.5 µm with decreasing diameters for increasing gas-to-liquid ratios. The survival rate was >90% of the control for the lowest gas-to-liquid ratio. For higher ratios, cell survival decreased to approximately 50%. Further experiments were performed with the design, which had shown the highest survival rates. After seven days, no significant differences in metabolic activity were observed. The apoptosis rates were not influenced by aerosolization, while high gas-to-liquid ratios caused increased necrosis levels. Tri-lineage differentiation potential into adipocytes, chondrocytes, and osteoblasts was not negatively influenced by aerosolization. Thus, the effervescent aerosolization principle was proven suitable for cell applications requiring reduced amounts of supplied air. This is the first time an effervescent atomizer was used for cell processing.
KW  - tri-lineage differentiation
KW  - survival
KW  - twin-fluid atomizer
KW  - adipose-derived stromal cells (ASCs)
KW  - cell atomization
KW  - cell aerosolization
Y1  - 2022
U6  - https://doi.org/10.3390/pharmaceutics14112421
N1  - This article belongs to the Special Issue "Stromal, Stem, Signaling Cells: The Multiple Roles and Applications of Mesenchymal Cells"
VL  - 14
IS  - 11
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Breuß, Michael
A1  - Kleefeld, Andreas
T1  - Implicit monotone difference methods for scalar conservation laws with source terms
JF  - Acta Mathematica Vietnamica
N2  - In this article, a concept of implicit methods for scalar conservation laws in one or more spatial dimensions allowing also for source terms of various types is presented. This material is a significant extension of previous work of the first author (Breuß SIAM J. Numer. Anal. 43(3), 970–986 2005). Implicit notions are developed that are centered around a monotonicity criterion. We demonstrate a connection between a numerical scheme and a discrete entropy inequality, which is based on a classical approach by Crandall and Majda. Additionally, three implicit methods are investigated using the developed notions. Next, we conduct a convergence proof which is not based on a classical compactness argument. Finally, the theoretical results are confirmed by various numerical tests.
KW  - Entropy solution
KW  - Source term
KW  - Monotone methods
KW  - Implicit methods
KW  - Finite difference methods
KW  - Conservation laws
Y1  - 2020
U6  - https://doi.org/10.1007/s40306-019-00354-1
SN  - 2315-4144
N1  - Corresponding author: Andreas Kleefeld
VL  - 45
SP  - 709
EP  - 738
PB  - Springer Singapore
CY  - Singapore
ER  -