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  - 
TY  - JOUR
A1  - Gaigall, Daniel
T1  - Hoeffding-Blum-Kiefer-Rosenblatt independence test statistic on partly not identically distributed data
JF  - Communications in Statistics - Theory and Methods
N2  - The established Hoeffding-Blum-Kiefer-Rosenblatt independence test statistic is investigated for partly not identically distributed data. Surprisingly, it turns out that the statistic has the well-known distribution-free limiting null distribution of the classical criterion under standard regularity conditions. An application is testing goodness-of-fit for the regression function in a non parametric random effects meta-regression model, where the consistency is obtained as well. Simulations investigate size and power of the approach for small and moderate sample sizes. A real data example based on clinical trials illustrates how the test can be used in applications.
KW  - Brownian Pillow
KW  - Hoeffding-Blum-Kiefer-Rosenblatt independence test
KW  - not identically distributed
KW  - random effects meta-regression model
Y1  - 2020
U6  - https://doi.org/10.1080/03610926.2020.1805767
SN  - 1532-415X
VL  - 51
IS  - 12
SP  - 4006
EP  - 4028
PB  - Taylor & Francis
CY  - London
ER  - 
TY  - JOUR
A1  - Baringhaus, Ludwig
A1  - Gaigall, Daniel
T1  - On an asymptotic relative efficiency concept based on expected volumes of confidence regions
JF  - Statistics - A Journal of Theoretical and Applied Statistic
N2  - The paper deals with an asymptotic relative efficiency concept for confidence regions of multidimensional parameters that is based on the expected volumes of the confidence regions. Under standard conditions the asymptotic relative efficiencies of confidence regions are seen to be certain powers of the ratio of the limits of the expected volumes. These limits are explicitly derived for confidence regions associated with certain plugin estimators, likelihood ratio tests and Wald tests. Under regularity conditions, the asymptotic relative efficiency of each of these procedures with respect to each one of its competitors is equal to 1. The results are applied to multivariate normal distributions and multinomial distributions in a fairly general setting.
KW  - Volume of confidence regions
KW  - asymptotic relative efficiency
KW  - likelihood ratio test
KW  - multivariate normal distribution
KW  - multinomial distribution
Y1  - 2019
U6  - https://doi.org/10.1080/02331888.2019.1683560
SN  - 1029-4910
VL  - 53
IS  - 6
SP  - 1396
EP  - 1436
PB  - Taylor & Francis
CY  - London
ER  - 
TY  - JOUR
A1  - Baringhaus, Ludwig
A1  - Gaigall, Daniel
T1  - On an independence test approach to the goodness-of-fit problem
JF  - Journal of Multivariate Analysis
N2  - Let X₁,…,Xₙ be independent and identically distributed random variables with distribution F. Assuming that there are measurable functions f:R²→R and g:R²→R characterizing a family F of distributions on the Borel sets of R in the way that the random variables f(X₁,X₂),g(X₁,X₂) are independent, if and only if F∈F, we propose to treat the testing problem H:F∈F,K:F∉F by applying a consistent nonparametric independence test to the bivariate sample variables (f(Xᵢ,Xⱼ),g(Xᵢ,Xⱼ)),1⩽i,j⩽n,i≠j. A parametric bootstrap procedure needed to get critical values is shown to work. The consistency of the test is discussed. The power performance of the procedure is compared with that of the classical tests of Kolmogorov–Smirnov and Cramér–von Mises in the special cases where F is the family of gamma distributions or the family of inverse Gaussian distributions.
KW  - Goodness-of-fit test
KW  - Independence test
KW  - Parametric bootstrap
KW  - Vapnik–Čhervonenkis class
KW  - Gamma distribution
Y1  - 2015
U6  - https://doi.org/10.1016/j.jmva.2015.05.013
SN  - 0047-259X
VL  - 2015
IS  - 140
SP  - 193
EP  - 208
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Engelmann, Ulrich M.
A1  - Simsek, Beril
A1  - Shalaby, Ahmed
A1  - Krause, Hans-Joachim
T1  - Key contributors to signal generation in frequency mixing magnetic detection (FMMD): an in silico study
JF  - Sensors
N2  - Frequency mixing magnetic detection (FMMD) is a sensitive and selective technique to detect magnetic nanoparticles (MNPs) serving as probes for binding biological targets. Its principle relies on the nonlinear magnetic relaxation dynamics of a particle ensemble interacting with a dual frequency external magnetic field. In order to increase its sensitivity, lower its limit of detection and overall improve its applicability in biosensing, matching combinations of external field parameters and internal particle properties are being sought to advance FMMD. In this study, we systematically probe the aforementioned interaction with coupled Néel–Brownian dynamic relaxation simulations to examine how key MNP properties as well as applied field parameters affect the frequency mixing signal generation. It is found that the core size of MNPs dominates their nonlinear magnetic response, with the strongest contributions from the largest particles. The drive field amplitude dominates the shape of the field-dependent response, whereas effective anisotropy and hydrodynamic size of the particles only weakly influence the signal generation in FMMD. For tailoring the MNP properties and parameters of the setup towards optimal FMMD signal generation, our findings suggest choosing large particles of core sizes dc > 25 nm nm with narrow size distributions (σ < 0.1) to minimize the required drive field amplitude. This allows potential improvements of FMMD as a stand-alone application, as well as advances in magnetic particle imaging, hyperthermia and magnetic immunoassays.
KW  - key performance indicators
KW  - magnetic biosensing
KW  - coupled Néel–Brownian relaxation dynamics
KW  - frequency mixing magnetic detection
KW  - magnetic relaxation
KW  - micromagnetic simulation
KW  - magnetic nanoparticles
Y1  - 2024
U6  - https://doi.org/10.3390/s24061945
SN  - 1424-8220
N1  - This article belongs to the Special Issue "Advances in Magnetic Sensors and Their Applications"
VL  - 24
IS  - 6
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Horbach, Andreas
A1  - Staat, Manfred
T1  - Optical strain measurement for the modeling of surgical meshes and their porosity
JF  - Current Directions in Biomedical Engineering
N2  - The porosity of surgical meshes makes them flexible for large elastic deformation and establishes the healing conditions of good tissue in growth. The biomechanic modeling of orthotropic and compressible materials requires new materials models and simulstaneoaus fit of deformation in the load direction as well as trannsversely to to load. This nonlinear modeling can be achieved by an optical deformation measurement. At the same time the full field deformation measurement allows the dermination of the change of porosity with deformation. Also the socalled effective porosity, which has been defined to asses the tisssue interatcion with the mesh implants, can be determined from the global deformation of the surgical meshes.
Y1  - 2018
U6  - https://doi.org/10.1515/cdbme-2018-0045
SN  - 2364-5504
VL  - Band 4
IS  - 1
SP  - 181
EP  - 184
PB  - De Gruyter
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Akimbekov, Nuraly S.
A1  - Digel, Ilya
A1  - Tastambek, Kuanysh T.
A1  - Kozhahmetova, Marzhan
A1  - Sherelkhan, Dinara K.
A1  - Tauanov, Zhandos
T1  - Hydrogenotrophic methanogenesis in coal-bearing environments: Methane production, carbon sequestration, and hydrogen availability
JF  - International Journal of Hydrogen Energy
N2  - Methane is a valuable energy source helping to mitigate the growing energy demand worldwide. However, as a potent greenhouse gas, it has also gained additional attention due to its environmental impacts. The biological production of methane is performed primarily hydrogenotrophically from H2 and CO2 by methanogenic archaea. Hydrogenotrophic methanogenesis also represents a great interest with respect to carbon re-cycling and H2 storage. The most significant carbon source, extremely rich in complex organic matter for microbial degradation and biogenic methane production, is coal. Although interest in enhanced microbial coalbed methane production is continuously increasing globally, limited knowledge exists regarding the exact origins of the coalbed methane and the associated microbial communities, including hydrogenotrophic methanogens. Here, we give an overview of hydrogenotrophic methanogens in coal beds and related environments in terms of their energy production mechanisms, unique metabolic pathways, and associated ecological functions.
KW  - Coal
KW  - Methanogenesis
KW  - Methane
KW  - Hydrogenotrophic methanogens
KW  - H2
Y1  - 2024
U6  - https://doi.org/10.1016/j.ijhydene.2023.09.223
SN  - 1879-3487 (online)
SN  - 0360-3199 (print)
VL  - 52
IS  - Part D
SP  - 1264
EP  - 1277
PB  - Elsevier
CY  - New York
ER  - 
TY  - JOUR
A1  - Grotendorst, Johannes
A1  - Scott, Tony C.
A1  - Aubert-Frécon, Monique
A1  - Andrae, D.
A1  - Morgan III, J. D.
A1  - Glasser, M. L.
T1  - Exchange Energy for Two-Active-Electron Diatomic Systems within the Surface Integral Method / Scott,T. C .; Aubert-Frécon, M. ; Andrae, D. ; Grotendorst, J. ; Morgan III, J. D. ; Glasser, M. L.
JF  - Applicable Algebra in Engineering, Communication and Computing. 15 (2004), H. 2
Y1  - 2004
SN  - 0938-1279
N1  - zugl. Technical Report FZJ-ZAM-IB-2004-02, April 2004, 24 pages
SP  - 101
EP  - 128
ER  -