TY  - CHAP
A1  - Olderog, M.
A1  - Mohr, P.
A1  - Beging, Stefan
A1  - Tsoumpas, C.
A1  - Ziemons, Karl
T1  - Simulation study on the role of tissue-scattered events in improving sensitivity for a compact time of flight compton positron emission tomograph
T2  - 2020 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC)
N2  - In positron emission tomography improving time, energy and spatial detector resolutions and using Compton kinematics introduces the possibility to reconstruct a radioactivity distribution image from scatter coincidences, thereby enhancing image quality. The number of single scattered coincidences alone is in the same order of magnitude as true coincidences. In this work, a compact Compton camera module based on monolithic scintillation material is investigated as a detector ring module. The detector interactions are simulated with Monte Carlo package GATE. The scattering angle inside the tissue is derived from the energy of the scattered photon, which results in a set of possible scattering trajectories or broken line of response. The Compton kinematics collimation reduces the number of solutions. Additionally, the time of flight information helps localize the position of the annihilation. One of the questions of this investigation is related to how the energy, spatial and temporal resolutions help confine the possible annihilation volume. A comparison of currently technically feasible detector resolutions (under laboratory conditions) demonstrates the influence on this annihilation volume and shows that energy and coincidence time resolution have a significant impact. An enhancement of the latter from 400 ps to 100 ps leads to a smaller annihilation volume of around 50%, while a change of the energy resolution in the absorber layer from 12% to 4.5% results in a reduction of 60%. The inclusion of single tissue-scattered data has the potential to increase the sensitivity of a scanner by a factor of 2 to 3 times. The concept can be further optimized and extended for multiple scatter coincidences and subsequently validated by a reconstruction algorithm.
Y1  - 2021
SN  - 978-1-7281-7693-2
U6  - http://dx.doi.org/10.1109/NSS/MIC42677.2020.9507901
N1  - 2020 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC), 31 Oct.-7 Nov. 2020, Boston, MA, USA
PB  - IEEE
ER  - 
TY  - THES
A1  - Oflaz, Hakan
T1  - Entwicklung eines Prototypen zur Prognose von Frühgeburten : ein biomedizintechnischer Ansatz
Y1  - 2012
U6  - http://dx.doi.org/10.4126/38m-004639208
N1  - Köln, Univ., Diss., 2012
PB  - Deutsche Zentralbibliothek für Medizin
CY  - Köln
ER  - 
TY  - JOUR
A1  - Oberländer, Jan
A1  - Mayer, Marlena
A1  - Greeff, Anton
A1  - Keusgen, Michael
A1  - Schöning, Michael Josef
T1  - Spore-based biosensor to monitor the microbicidal efficacy of gaseous hydrogen peroxide sterilization processes
JF  - Biosensors and Bioelectronics
N2  - In this work, a spore-based biosensor is evaluated to monitor the microbicidal efficacy of sterilization processes applying gaseous hydrogen peroxide (H2O2). The sensor is based on interdigitated electrode structures (IDEs) that have been fabricated by means of thin-film technologies. Impedimetric measurements are applied to study the effect of sterilization process on spores of Bacillus atrophaeus. This resilient microorganism is commonly used in industry to proof the sterilization efficiency. The sensor measurements are accompanied by conventional microbiological challenge tests, as well as morphological characterizations with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The sensor measurements are correlated with the microbiological test routines. In both methods, namely the sensor-based and microbiological one, a tailing effect has been observed. The results are evaluated and discussed in a three-dimensional calibration plot demonstrating the sensor's suitability to enable a rapid process decision in terms of a successfully performed sterilization.
Y1  - 2018
U6  - http://dx.doi.org/10.1016/j.bios.2017.12.045
SN  - 0956-5663
VL  - 104
SP  - 87
EP  - 94
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Oberländer, Jan
A1  - Kirchner, Patrick
A1  - Keusgen, Michael
A1  - Schöning, Michael Josef
T1  - Strategies in developing thin-film sensors for monitoring aseptic food processes : Theoretical considerations and investigations of passivation materials
JF  - Electrochimica Acta
N2  - The sterilization of packages in aseptic food processes is highly significant to maintain a consumer-safe product with extended shelf-life. Today, the sterilization of food packages is predominantly accomplished by gaseous hydrogen peroxide (H2O2) in combination with heat. In order to monitor this sterilization process, calorimetric gas sensors as differential set-up of two platinum temperature sensors representing a catalytically active (additionally deposition of MnO2) and a passive segment have been recently developed. The temperature rise of the exothermic decomposition serves as an indicator of the present H2O2 concentration. In the present work, a theoretical approach considering the sensor’s thermochemistry and physical transport phenomena was formulated to evaluate the temperature rise based on the energy content of gaseous H2O2. In a further part of this work, three polymers have been analyzed with respect to their application as passivation materials. The examined polymers are photoresist SU-8, perfluoroalkoxy (PFA) and fluorinated ethylene propylene (FEP). Thermal analyses by means of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) have been conducted to determine the operation limits of the polymers. The overall chemical resistance and stability of the polymers against the harsh environmental conditions during the sterilization process have been examined by attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR).
Y1  - 2015
U6  - http://dx.doi.org/10.1016/j.electacta.2015.06.126
SN  - 0013-4686
VL  - 183
SP  - 130
EP  - 136
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - CHAP
A1  - Oberländer, Jan
A1  - Kirchner, Patrick
A1  - Keusgen, M.
A1  - Schöning, Michael Josef
T1  - Flexible polyimide-based calorimetric gas sensors for monitoring hy-drogen peroxide in sterilisation processes of aseptic filling machines
T2  - Sensoren und Messsysteme 2014 ; Beiträge der 17. GMA/ITG-Fachtagung vom 3. bis 4. Juni 2014 in Nürnberg. (ITG-Fachbericht ; 250)
Y1  - 2014
SN  - 978-3-8007-3622-5
SP  - 1
EP  - 4
PB  - VDE-Verl.
CY  - Düsseldorf
ER  - 
TY  - JOUR
A1  - Oberländer, Jan
A1  - Kirchner, Patrick
A1  - Boyen, Hans-Gerd
A1  - Schöning, Michael Josef
T1  - Detection of hydrogen peroxide vapor by use of manganese(IV) oxide as catalyst for calorimetric gas sensors
JF  - Physica status solidi A: Applications and materials science
N2  - In this work, the catalyst manganese(IV) oxide (MnO2), of calorimetric gas sensors (to monitor the sterilization agent vaporized hydrogen peroxide) has been investigated in more detail. Chemical analyses by means of X-ray-induced photoelectron spectroscopy have been performed to unravel the surface chemistry prior and after exposure to hydrogen peroxide vapor at elevated temperature, as applied in the sterilization processes of beverage cartons. The surface characterization reveals a change in oxidation states of the metal oxide catalyst after exposure to hydrogen peroxide. Additionally, a cleaning effect of the catalyst, which itself is attached to the sensor surface by means of a polymer interlayer, could be observed.
Y1  - 2014
U6  - http://dx.doi.org/10.1002/pssa.201330359
SN  - 1521-396X (E-Journal); 1862-6319 (E-Journal); 0031-8965 (Print); 1862-6300 (Print)
VL  - 211
IS  - 6
SP  - 1372
EP  - 1376
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Oberländer, Jan
A1  - Jildeh, Zaid B.
A1  - Kirchner, Patrick
A1  - Wendeler, Luisa
A1  - Bromm, Alexander
A1  - Iken, Heiko
A1  - Wagner, Patrick
A1  - Keusgen, Michael
A1  - Schöning, Michael Josef
T1  - Study of Interdigitated Electrode Arrays Using Experiments and Finite Element Models for the Evaluation of Sterilization Processes
JF  - Sensors
N2  - In this work, a sensor to evaluate sterilization processes with hydrogen peroxide vapor has been characterized. Experimental, analytical and numerical methods were applied to evaluate and study the sensor behavior. The sensor set-up is based on planar interdigitated electrodes. The interdigitated electrode structure consists of 614 electrode fingers spanning over a total sensing area of 20 mm2. Sensor measurements were conducted with and without microbiological spores as well as after an industrial sterilization protocol. The measurements were verified using an analytical expression based on a first-order elliptical integral. A model based on the finite element method with periodic boundary conditions in two dimensions was developed and utilized to validate the experimental findings.
Y1  - 2015
U6  - http://dx.doi.org/10.3390/s151026115
SN  - 1424-8220
N1  - This article belongs to the Special Issue "Gas Sensors—Designs and Applications"
VL  - 15
IS  - 10
SP  - 26115
EP  - 26127
PB  - MDPI
CY  - Basel
ER  - 
TY  - CHAP
A1  - Oberländer, Jan
A1  - Jildeh, Zaid B.
A1  - Kirchner, Patrick
A1  - Wendeler, Luisa
A1  - Bromm, Alexander
A1  - Iken, Heiko
A1  - Wagner, Patrick
A1  - Keusgen, Michael
A1  - Schöning, Michael Josef
T1  - Experimental and numerical evaluation of interdigitated electrode array for monitoring gaseous sterilization processes
T2  - 12. Dresdner Sensor-Symposium 2015
Y1  - 2015
U6  - http://dx.doi.org/10.5162/12dss2015/P3.11
SP  - 163
EP  - 168
ER  - 
TY  - JOUR
A1  - Oberländer, Jan
A1  - Bromm, Alexander
A1  - Wendeler, Luisa
A1  - Iken, Heiko
A1  - Palomar Duran, Marlena
A1  - Greeff, Anton
A1  - Kirchner, Patrick
A1  - Keusgen, Michael
A1  - Schöning, Michael Josef
T1  - Towards a biosensor to monitor the sterilisation efficiency of aseptic filling machines
JF  - Physica status solidi (a)
N2  - Sterilisation processes are compulsory in medicine, pharmacy, and food industries to prevent infections of consumers and microbiological contaminations of products. Monitoring the sterilisation by conventional microbiological methods is time- and lab-consuming. To overcome this problem, in this work a novel biosensor has been proposed. The sensor enables a fast method to evaluate sterilisation processes. By means of thin-film technology the sensor's transducer structures in form of IDEs (interdigitated electrodes) have been fabricated on a silicon substrate. Physical characterisation of the developed sensor was done by AFM, SEM, and profilometry. Impedance analyses were conducted for the electrical characterisation. As microbiological layer spores of B. atrophaeus have been immobilised on the sensing structure; spores of this type are a well-known sterilisation test organism. Impedance measurements at a fixed frequency over time were performed to monitor the immobilisation process. A sterilisation process according to aseptic filling machines was applied to demonstrate the sensor functionality. After both, immobilisation and sterilisation, a change in impedance could successfully be detected.
Y1  - 2015
U6  - http://dx.doi.org/10.1002/pssa.201431900
SN  - 1862-6319
VL  - 212
IS  - 6
SP  - 1299
EP  - 1305
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - CHAP
A1  - Oberländer, Jan
A1  - Arreola, Julio
A1  - Hansen, Christina
A1  - Greeff, Anton
A1  - Mayer, Marlena
A1  - Keusgen, Michael
A1  - Schöning, Michael Josef
T1  - Impedimetric Biosensor to Enable Fast Evaluation of Gaseous Sterilization Processes
T2  - MDPI Proceedings
Y1  - 2017
U6  - http://dx.doi.org/10.3390/proceedings1040435
N1  - Eurosensors 2017 Conference, Paris, France, 3–6 September 2017
VL  - 1
IS  - 4
ER  - 
TY  - JOUR
A1  - Näther, Niko
A1  - Rolka, David
A1  - Poghossian, Arshak
A1  - Koudelka-Hep, M.
A1  - Schöning, Michael Josef
T1  - Two microcell flow-injection analysis (FIA) platforms for capacitive silicon-based field-effect sensors
JF  - Electrochimica Acta. 51 (2005), H. 5
Y1  - 2005
SN  - 0013-4686
U6  - http://dx.doi.org/10.1016/j.electacta.2005.04.066
SP  - 924
EP  - 929
ER  - 
TY  - CHAP
A1  - Näther, Niko
A1  - Poghossian, Arshak
A1  - Platen, J.
A1  - Yoshinobu, T.
A1  - Koudelka-Hep, M.
A1  - Schöning, Michael Josef
T1  - Multi-parameter sensing of both physical and (bio-)chemical quantities using the same transducer principle
T2  - Biochemical sensing utilisation of micro- and nanotechnologies : Warsaw, [23rd - 26th] November 2005 / ed. by M. Mascini ...
Y1  - 2006
SP  - 172
EP  - 181
CY  - Warsaw
ER  - 
TY  - JOUR
A1  - Näther, Niko
A1  - Henkel, Hartmut
A1  - Schneider, Andreas
A1  - Schöning, Michael Josef
T1  - Investigation of different catalytically active and passive materials for realising a hydrogen peroxide gas sensor
JF  - physica status solidi (a) . 206 (2009), H. 3
Y1  - 2009
SN  - 1862-6319
N1  - Special Issue: Engineering of Functional Interfaces (EnFI 08)
SP  - 449
EP  - 454
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Näther, Niko
A1  - Emmerich, Rüdiger
A1  - Berger, Jörg
A1  - Friedrich, Peter
A1  - Henkel, Hartmut
A1  - Schneider, Andreas
A1  - Schöning, Michael Josef
T1  - A novel gas-phase hydrogen peroxide sensor basing on a combined physical/chemical transduction mechanism
JF  - Nanofunctional materials, nanostructures, and novel devices for biological and chemical detection : November 27 - December 1, 2006, Boston, Massachusetts, USA ; [at the 2006 MRS Fall Meeting].
Y1  - 2006
SN  - 978-1-60423-407-7
N1  - Materials Research Society symposium proceedings ; 951 ; MRS fall meeting ; (2006.11.27-12.01 : ; Boston, Mass.)
SP  - 63
EP  - 68
PB  - Materials Research Soc.
CY  - Warrendale, Pa.
ER  - 
TY  - JOUR
A1  - Näther, Niko
A1  - Auger, V.
A1  - Poghossian, Arshak
A1  - Koudelka-Hep, M.
A1  - Schöning, Michael Josef
T1  - A miniaturized flow-through cell in SU-8 technique for EIS sensors
JF  - Biomedizinische Technik. 49 (2004), H. 2
Y1  - 2004
SN  - 0932-4666
SP  - 994
EP  - 995
ER  - 
TY  - JOUR
A1  - Novacek, V.
A1  - Tran, Thanh Ngoc
A1  - Klinge, U.
A1  - Tolba, R. H.
A1  - Staat, Manfred
A1  - Bronson, D. G.
A1  - Miesse, A. M.
A1  - Whiffen, J.
A1  - Turquier, F.
T1  - Finite element modelling of stapled colorectal end-to-end anastomosis : Advantages of variable height stapler design
JF  - Journal of Biomechanics
N2  - The impact of surgical staplers on tissues has been studied mostly in an empirical manner. In this paper, finite element method was used to clarify the mechanics of tissue stapling and associated phenomena. Various stapling modalities and several designs of circular staplers were investigated to evaluate the impact of the device on tissues and mechanical performance of the end-to-end colorectal anastomosis. Numerical simulations demonstrated that a single row of staples is not adequate to resist leakage due to non-linear buckling and opening of the tissue layers between two adjacent staples. Compared to the single staple row configuration, significant increase in stress experienced by the tissue at the inner staple rows was observed in two and three rows designs. On the other hand, adding second and/or third staple row had no effect on strain in the tissue inside the staples. Variable height design with higher staples in outer rows significantly reduced the stresses and strains in outer rows when compared to the same configuration with flat cartridge.
KW  - Variable height stapler design
KW  - Anastomotic leakage
KW  - Finite element modelling
KW  - End-to-end colorectal anastomosis
KW  - Surgical staplers
Y1  - 2012
U6  - http://dx.doi.org/10.1016/j.jbiomech.2012.07.021
SN  - 1873-2380
VL  - 45
IS  - 115
SP  - 2693
EP  - 2697
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Nomdedeu, Mar Monsonis
A1  - Willen, Christine
A1  - Schieffer, Andre
A1  - Arndt, Hartmut
T1  - Temperature-dependent ranges of coexistence in a model of a two-prey-one-predator microbial food web
JF  - Marine Biology
N2  - The objective of our study was to analyze the effects of temperature on the population dynamics of a three-species food web consisting of two prey bacteria (Pedobacter sp. and Acinetobacter johnsonii) and a protozoan predator (Tetrahymena pyriformis) as model organisms. We assessed the effects of temperature on the growth rates of all three species with the objective of developing a model with four differential equations based on the experimental data. The following hypotheses were tested at a theoretical level: Firstly, temperature changes can affect the dynamic behavior of a system by temperature-dependent parameters and interactions and secondly, food web response to temperature cannot be derived from the single species temperature response. The main outcome of the study is that temperature changes affect the parameter range where coexistence is possible within all three species. This has significant consequences on our ideas regarding the evaluation of effects of global warming.
Y1  - 2012
U6  - http://dx.doi.org/10.1007/s00227-012-1966-x
SN  - 1432-1793
VL  - 159
IS  - 11
SP  - 2423
EP  - 2430
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Nguyen-Xuan, H.
A1  - Rabczuk, T.
A1  - Nguyen-Thoi, T.
A1  - Tran, Thanh Ngoc
A1  - Nguyen-Thanh, N.
T1  - Computation of limit and shakedown loads using a node-based smoothed finite element method
JF  - International Journal for Numerical Methods in Engineering
N2  - This paper presents a novel numerical procedure for computing limit and shakedown loads of structures using a node-based smoothed FEM in combination with a primal–dual algorithm. An associated primal–dual form based on the von Mises yield criterion is adopted. The primal-dual algorithm together with a Newton-like iteration are then used to solve this associated primal–dual form to determine simultaneously both approximate upper and quasi-lower bounds of the plastic collapse limit and the shakedown limit. The present formulation uses only linear approximations and its implementation into finite element programs is quite simple. Several numerical examples are given to show the reliability, accuracy, and generality of the present formulation compared with other available methods.
Y1  - 2011
U6  - http://dx.doi.org/10.1002/nme.3317
SN  - 1097-0207
VL  - 90
IS  - 3
SP  - 287
EP  - 310
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Nguyen, Nhu Huynh
A1  - Duong, Minh Tuan
A1  - Tran, Thanh Ngoc
A1  - Pham, Phu Tinh
A1  - Grottke, O.
A1  - Tolba, R.
A1  - Staat, Manfred
T1  - Influence of a freeze–thaw cycle on the stress–stretch curves of tissues of porcine abdominal organs
JF  - Journal of Biomechanics
N2  - The paper investigates both fresh porcine spleen and liver and the possible decomposition of these organs under a freeze–thaw cycle. The effect of tissue preservation condition is an important factor which should be taken into account for protracted biomechanical tests. In this work, tension tests were conducted for a large number of tissue specimens from twenty pigs divided into two groups of 10. Concretely, the first group was tested in fresh state; the other one was tested after a freeze-thaw cycle which simulates the conservation conditions before biomechanical experiments. A modified Fung model for isotropic behavior was adopted for the curve fitting of each kind of tissues. Experimental results show strong effects of the realistic freeze–thaw cycle on the capsule of elastin-rich spleen but negligible effects on the liver which virtually contains no elastin. This different behavior could be explained by the autolysis of elastin by elastolytic enzymes during the warmer period after thawing. Realistic biomechanical properties of elastin-rich organs can only be expected if really fresh tissue is tested. The observations are supported by tests of intestines.
KW  - Autolysis
KW  - Decomposition
KW  - Freeze–thaw process
KW  - Spleen
KW  - Liver
Y1  - 2012
U6  - http://dx.doi.org/10.1016/j.jbiomech.2012.07.008
SN  - 1873-2380
VL  - 45
IS  - 14
SP  - 2382
EP  - 2386
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Nguyen, N.-H.
A1  - Raatschen, Hans-Jürgen
A1  - Staat, Manfred
T1  - A hyperelastic model of biological tissue materials in tubular organs
Y1  - 2010
N1  - ECCM 2010, IV European Conference on Computational Mechanics, Paris, France, May 16-21, 2010.
SP  - 1
EP  - 12
ER  -