TY  - JOUR
A1  - Bandodkar, Amay J.
A1  - Molinnus, Denise
A1  - Mirza, Omar
A1  - Guinovart, Tomas
A1  - Windmiller, Joshua R.
A1  - Valdes-Ramirez, Gabriela
A1  - Andrade, Francisco J.
A1  - Schöning, Michael Josef
A1  - Wang, Joseph
T1  - Epidermal tattoo potentiometric sodium sensors with wireless signal transduction for continuous non-invasive sweat monitoring
JF  - Biosensors and bioelectronics
N2  - This article describes the fabrication, characterization and application of an epidermal temporary-transfer tattoo-based potentiometric sensor, coupled with a miniaturized wearable wireless transceiver, for real-time monitoring of sodium in the human perspiration. Sodium excreted during perspiration is an excellent marker for electrolyte imbalance and provides valuable information regarding an individual's physical and mental wellbeing. The realization of the new skin-worn non-invasive tattoo-like sensing device has been realized by amalgamating several state-of-the-art thick film, laser printing, solid-state potentiometry, fluidics and wireless technologies. The resulting tattoo-based potentiometric sodium sensor displays a rapid near-Nernstian response with negligible carryover effects, and good resiliency against various mechanical deformations experienced by the human epidermis. On-body testing of the tattoo sensor coupled to a wireless transceiver during exercise activity demonstrated its ability to continuously monitor sweat sodium dynamics. The real-time sweat sodium concentration was transmitted wirelessly via a body-worn transceiver from the sodium tattoo sensor to a notebook while the subjects perspired on a stationary cycle. The favorable analytical performance along with the wearable nature of the wireless transceiver makes the new epidermal potentiometric sensing system attractive for continuous monitoring the sodium dynamics in human perspiration during diverse activities relevant to the healthcare, fitness, military, healthcare and skin-care domains.
Y1  - 2014
U6  - http://dx.doi.org/10.1016/j.bios.2013.11.039
SN  - 1873-4235 (E-Journal); 0956-5663 (Print)
VL  - 54
SP  - 603
EP  - 609
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Laack, Walter van
T1  - Our world is well ordered in measurement and number : or why natural constants are as they are
JF  - American Journal of Humanities and Social Sciences (AHSS)
N2  - All the important natural constants can be logically explained with and derived from the first four ordinal numbers, 1, 2, 3 and 4, its addition to ten and finally the standard values for obviously maximal feasibility Ω and the optimum in our world, the Golden Section (GS), i.e. the number sequences 273 and 618. They both are the first three numbers of irrational results by an arithmetical transformation of simple geometrical relationships by creating multiplicity out of singularity. Both of them show that the infinite is inherent in finiteness and explain in a simple way the smallest deviations and fluctuations between the physical AS-IS state and the obvious spiritual ideal behind: Wherever we look in this world, and especially in important key-positions, we regularly find these sequences. All of the above mentioned numbers so seem to be key players in our world, what can be demonstrated by the derivation of natural constants.
Y1  - 2013
U6  - http://dx.doi.org/10.11634/232907811301390
SN  - 2329-079X
SN  - 2329-0781
VL  - 1
IS  - 4
SP  - 219
EP  - 221
ER  - 
TY  - CHAP
A1  - Tran, Thanh Ngoc
A1  - Staat, Manfred
T1  - Shakedown analysis of Reissner-Mindlin plates using the edge-based smoothed finite element method
T2  - Direct methods for limit states in structures and materials / Dieter Weichert ; Alan Ponter, ed.
N2  - This paper concerns the development of a primal-dual algorithm for limit and shakedown analysis of Reissner-Mindlin plates made of von Mises material. At each optimization iteration, the lower bound of the shakedown load multiplier is calculated simultaneously with the upper bound using the duality theory. An edge-based smoothed finite element method (ES-FEM) combined with the discrete shear gap (DSG) technique is used to improve the accuracy of the solutions and to avoid the transverse shear locking behaviour. The method not only possesses all inherent features of convergence and accuracy from ES-FEM, but also ensures that the total number of variables in the optimization problem is kept to a minimum compared with the standard finite element formulation. Numerical examples are presented to demonstrate the effectiveness of the present method.
Y1  - 2014
SN  - 978-94-007-6826-0 (Print) 978-94-007-6827-7 (Online)
U6  - http://dx.doi.org/10.1007/978-94-007-6827-7_5
SP  - 101
EP  - 117
PB  - Springer
CY  - Dordrecht [u.a.]
ER  - 
TY  - JOUR
A1  - Staat, Manfred
T1  - Limit and shakedown analysis under uncertainty
JF  - International journal of computational methods : IJCM
Y1  - 2013
SN  - 0219-8762
SP  - Publ. online
PB  - World Scientific Publishing
CY  - Singapore
ER  - 
TY  - JOUR
A1  - Laack, Walter van
T1  - Why natural constants are as they are
JF  - British journal of arts and social sciences
Y1  - 2013
SN  - 2046-9578 (E-Journal)
VL  - Vol. 15
IS  - Nr. 2
SP  - 198
EP  - 203
PB  - BritishJournal Publ. Inc
CY  - London
ER  - 
TY  - JOUR
A1  - Iken, Heiko
A1  - Ahlborn, K.
A1  - Gerlach, F.
A1  - Vonau, W.
A1  - Zander, W.
A1  - Schubert, J.
A1  - Schöning, Michael Josef
T1  - Development of redox glasses and subsequent processing by means of pulsed laser deposition for realizing silicon-based thin-film sensors
JF  - Electrochimica acta
Y1  - 2013
SN  - 1873-3859 (E-Journal); 0013-4686 (Print)
SP  - Available online 30.8.2013
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - CHAP
A1  - Frotscher, Ralf
A1  - Goßmann, Matthias
A1  - Temiz Artmann, Aysegül
A1  - Staat, Manfred
T1  - Simulation of cardiac cell-seeded membranes using the edge-based smoothed FEM
T2  - 1st International Conference "Shell and Membrane Theories in Mechanics and Biology: From Macro- to Nanoscale Structures", Minsk, Belarus, Sept. 16-20, 2013
Y1  - 2013
SN  - 978-985-553-135-8
SP  - 165
EP  - 167
PB  - Verl. d. Weißruss. Staatl. Univ.
CY  - Minsk
ER  - 
TY  - JOUR
A1  - Schusser, Sebastian
A1  - Menzel, S.
A1  - Bäcker, Matthias
A1  - Leinhos, Marcel
A1  - Poghossian, Arshak
A1  - Wagner, P.
A1  - Schöning, Michael Josef
T1  - Degradation of thin poly(lactic acid) films: characterization by capacitance-voltage, atomic force microscopy, scanning electron microscopy and contact-angle measurements
JF  - Electrochimica Acta
Y1  - 2013
SN  - 1873-3859 (E-Journal); 0013-4686 (Print)
VL  - Vol. 113
SP  - 779
EP  - 784
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Porschen, W.
A1  - Gartzen, J.
A1  - Gewehr, K.
A1  - Mühlensiepen, H.
A1  - Weber, Hans-Joachim
A1  - [u.a.], 
T1  - In vivo assay of the radiation sensitivity of hypoxic tumour cells : influence of γ-rays, cyclotron neutrons, misonidazole, hyperthermia and mixed modalities
JF  - The British journal of cancer / Supplement
N2  - Tumour cell death can be evaluated in the living mouse by externally measuring the rate of loss of tumour-bound DNA tracer. By sequentially labelling the tumour-bearing animals with ¹²⁵IUdR and ¹³¹IUdR 50 h apart, the average tumour cells at the time of the second injection are labelled by ¹²⁵IUdR and the euoxic tumour cells are specifically labelled with ¹³¹IUdR. Tumour treatment at this stage of labelling permits the observation of the reaction of euoxic cells and average tumour cells and finally yields data on hypoxic cells and thus on the oxygen enhancement ratio. This information adds to results from tumour control and growth delay.

With this technique effects were analysed of 60-Co γ-rays, cyclotron neutrons (E = 6 MeV), misonidazole (500 mg/kg body wt) and hyperthermia (42°C water-bath), or combinations of these.

Misonidazole (15 min before irradiation) altered the oxygen enhancement ratio by a factor of 1·5 for γ-rays and of 1·1 for neutrons; when evaluated from tumour-growth delay and TCD-50 misonidazole gave a dose modifying factor of 1·47 for γ-rays and of 1·2-1·3 for neutrons.

Based on percentage tumour regression 100 days after treatment, the enhancement ratio from hyperthermia (after irradiation) was 2·75 for γ-rays (at 10 Gray) and 2·2 for neutrons (at 3·2 Gray). For neutrons combined with misonidazole and hyperthermia the ratio was 2·4.

These results demonstrate that effects of neutron irradiation may be modified by electron-affinic substances and/or hyperthermia.
Y1  - 1978
SN  - 0306-9443
N1  - Section 6: Sensitization and Hypoxic Cytotoxicity: Effects of Hyperthermia and High Let
IS  - 3
SP  - 194
EP  - 197
PB  - Lewis
CY  - London
ER  - 
TY  - CHAP
A1  - Weber, Hans-Joachim
A1  - Porschen, W.
A1  - Dietzel, F.
A1  - [u.a.], 
ED  - Streffer, Christian
T1  - In vivo analysis of the influence of combined hyperthermia and gamma irradiation on euoxic and hypoxic tumor cells
T2  - Cancer therapy by hyperthermia and radiation : [proceedings of the 2. International Symposium on Cancer Therapy by Hyperthermia and Radiation, Essen, 2.-4.6.1977]
Y1  - 1978
SN  - 0-8067-1701-7
SN  - 3-541-71701-7
SP  - 276
EP  - 277
PB  - Urban and Schwarzenberg
CY  - Baltimore ; Munich [u.a.]
ER  - 
TY  - JOUR
A1  - Laack, Walter van
T1  - The genetic code should be seen as a positioning code
JF  - British journal of arts and social sciences. Vol. 14 (2013), No. 1
Y1  - 2013
SN  - 2046-9578
SP  - 93
EP  - 97
ER  - 
TY  - JOUR
A1  - Kramer, Friederike
A1  - Halamkova, Lenka
A1  - Poghossian, Arshak
A1  - Schöning, Michael Josef
A1  - Katz, Evgeny
A1  - Halamek, Jan
T1  - Biocatalytic analysis of biomarkers for forensic identification of ethnicity between Caucasian and African American
JF  - The analyst. August 2013
Y1  - 2013
SN  - 1364-5528 (E-Journal); 0003-2654 (Print)
VL  - Vol. 138
SP  - 6251
EP  - 6257
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Bohrn, Ulrich
A1  - Mucha, Andreas
A1  - Werner, Frederik
A1  - Trattner, Barbara
A1  - Bäcker, Matthias
A1  - Krumbe, Christoph
A1  - Schienle, Meinrad
A1  - Stütz, Evamaria
A1  - Schmitt-Landsiedel, Doris
A1  - Fleischer, Maximilian
A1  - Wagner, Patrick
A1  - Schöning, Michael Josef
T1  - A critical comparison of cell-based sensor systems for the detection of Cr (VI) in aquatic environment
JF  - Sensors and actuators. B: Chemical
Y1  - 2013
SN  - 1873-3077 (E-Journal); 0925-4005 (Print)
VL  - Vol. 182
SP  - 58
EP  - 65
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Miyamoto, Ko-ichiro
A1  - Ichimura, Hiroki
A1  - Wagner, Torsten
A1  - Schöning, Michael Josef
A1  - Yoshinobu, Tatsuo
T1  - Chemical imaging of the concentration profile of ion diffusion in a microfluidic channel
JF  - Sensors and actuators. B: Chemical
N2  - The chemical imaging sensor is a device to visualize the spatial distribution of chemical species based on the principle of LAPS (light-addressable potentiometric sensor), which is a field-effect chemical sensor based on semiconductor. In this study, the chemical imaging sensor has been applied to investigate the ion profile of laminar flows in a microfluidic channel. The chemical images (pH maps) were collected in a Y-shaped microfluidic channel while injecting HCl and NaCl solutions into two branches. From the chemical images, it was clearly observed that the injected solutions formed laminar flows in the channel. In addition, ion diffusion across the laminar flows was observed, and the diffusion coefficient could be derived by fitting the pH profiles to the Fick's equation.
Y1  - 2013
U6  - http://dx.doi.org/10.1016/j.snb.2013.04.057
SN  - 1873-3077 (E-Journal); 0925-4005 (Print)
N1  - Part of special issue "Selected Papers from the 26th European Conference on Solid-State Transducers"
VL  - 189
SP  - 240
EP  - 245
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - CHAP
A1  - Gerhards, Michael
A1  - Sander, Volker
A1  - Belloum, Adam
T1  - Seamlessly enabling the use of cloud resources in workflows
T2  - Cloud Computing 2013 : The Fourth International Conference on Cloud Computing, GRIDs, and Virtualization : May 27 - June 1, 2013 - Valencia, Spain
Y1  - 2013
SN  - 978-1-61208-271-4
SP  - 108
EP  - 114
PB  - Curren
CY  - Red Hook, NY
ER  - 
TY  - CHAP
A1  - Dikta, Gerhard
T1  - Fundamentals of applied probability and basic statistics
T2  - Critical care nephrology / [Hrsg.:] Claudio Ronco and Rinaldo Bellomo
Y1  - 1998
SN  - 978-94-010-6306-7
SP  - 51
EP  - 61
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - CHAP
A1  - Weber, Hans-Joachim
T1  - Applied physics of compressible and incompressible fluids
T2  - Critical care nephrology / [Hrsg.:] Claudio Ronco and Rinaldo Bellomo
Y1  - 1998
SN  - 978-94-010-6306-7
SP  - 63
EP  - 84
PB  - Springer
CY  - Dordrecht
ER  - 
TY  - JOUR
A1  - Murib, M. S.
A1  - Grinsven, B. van
A1  - Grieten, L.
A1  - Janssens, S. D.
A1  - Vermeeren, V.
A1  - Eersels, K.
A1  - Broeders, J.
A1  - Ameloot, M.
A1  - Michiels, L.
A1  - Ceuninck, W. De
A1  - Haenen, K.
A1  - Schöning, Michael Josef
A1  - Wagner, Patrick
T1  - Electronic monitoring of chemical DNA denaturation on nanocrystalline diamond electrodes with different molarities and flow rates
JF  - Physica Status Solidi (A). Vol. 210 (2013), iss. 5
Y1  - 2013
SN  - 0031-8965
SP  - 911
EP  - 917
PB  - Wiley-VCH
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Huck, Christina
A1  - Schiffels, Johannes
A1  - Herrera, Cony N.
A1  - Schelden, Maximilian
A1  - Selmer, Thorsten
A1  - Poghossian, Arshak
A1  - Baumann, Marcus
A1  - Wagner, Patrick
A1  - Schöning, Michael Josef
T1  - Metabolic responses of Escherichia coli upon glucose pulses captured by a capacitive field-effect sensor
JF  - Physica Status Solidi (A)
N2  - Living cells are complex biological systems transforming metabolites taken up from the surrounding medium. Monitoring the responses of such cells to certain substrate concentrations is a challenging task and offers possibilities to gain insight into the vitality of a community influenced by the growth environment. Cell-based sensors represent a promising platform for monitoring the metabolic activity and thus, the “welfare” of relevant organisms. In the present study, metabolic responses of the model bacterium Escherichia coli in suspension, layered onto a capacitive field-effect structure, were examined to pulses of glucose in the concentration range between 0.05 and 2 mM. It was found that acidification of the surrounding medium takes place immediately after glucose addition and follows Michaelis–Menten kinetic behavior as a function of the glucose concentration. In future, the presented setup can, therefore, be used to study substrate specificities on the enzymatic level and may as well be used to perform investigations of more complex metabolic responses. Conclusions and perspectives highlighting this system are discussed.
Y1  - 2013
U6  - http://dx.doi.org/10.1002/pssa.201200900
SN  - 0031-8965
VL  - 210
IS  - 5
SP  - 926
EP  - 931
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Schusser, Sebastian
A1  - Leinhos, Marcel
A1  - Bäcker, Matthias
A1  - Poghossian, Arshak
A1  - Wagner, Patrick
A1  - Schöning, Michael Josef
T1  - Impedance spectroscopy: A tool for real-time in situ monitoring of the degradation of biopolymers
JF  - Physica Status Solidi (A)
N2  - Investigation of the degradation kinetics of biodegradable polymers is essential for the development of implantable biomedical devices with predicted biodegradability. In this work, an impedimetric sensor has been applied for real-time and in situ monitoring of degradation processes of biopolymers. The sensor consists of two platinum thin-film electrodes covered by a polymer film to be studied. The benchmark biomedical polymer poly(D,L-lactic acid) (PDLLA) was used as a model system. PDLLA films were deposited on the sensor structure from a polymer solution by using the spin-coating method. The degradation kinetics of PDLLA films have been studied in alkaline solutions of pH 9 and 12 by means of an impedance spectroscopy (IS) method. Any changes in a polymer capacitance/resistance induced by water uptake and/or polymer degradation will modulate the global impedance of the polymer-covered sensor that can be used as an indicator of the polymer degradation. The degradation rate can be evaluated from the time-dependent impedance spectra. As expected, a faster degradation has been observed for PDLLA films exposed to pH 12 solution.
Y1  - 2013
U6  - http://dx.doi.org/10.1002/pssa.201200941
SN  - 1521-396X ; 0031-8965
VL  - 210
IS  - 5
SP  - 905
EP  - 910
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Poghossian, Arshak
A1  - Weil, M.
A1  - Cherstvy, A. G.
A1  - Schöning, Michael Josef
T1  - Electrical monitoring of polyelectrolyte multilayer formation by means of capacitive field-effect devices
JF  - Analytical and bioanalytical chemistry
N2  - The semiconductor field-effect platform represents a powerful tool for detecting the adsorption and binding of charged macromolecules with direct electrical readout. In this work, a capacitive electrolyte–insulator–semiconductor (EIS) field-effect sensor consisting of an Al-p-Si-SiO2 structure has been applied for real-time in situ electrical monitoring of the layer-by-layer formation of polyelectrolyte (PE) multilayers (PEM). The PEMs were deposited directly onto the SiO2 surface without any precursor layer or drying procedures. Anionic poly(sodium 4-styrene sulfonate) and cationic weak polyelectrolyte poly(allylamine hydrochloride) have been chosen as a model system. The effect of the ionic strength of the solution, polyelectrolyte concentration, number and polarity of the PE layers on the characteristics of the PEM-modified EIS sensors have been studied by means of capacitance–voltage and constant-capacitance methods. In addition, the thickness, surface morphology, roughness and wettabilityof the PE mono- and multilayers have been characterised by ellipsometry, atomic force microscopy and water contact-angle methods, respectively. To explain potential oscillations on the gate surface and signal behaviour of the capacitive field-effect EIS sensor modified with a PEM, a simplified electrostatic model that takes into account the reduced electrostatic screening of PE charges by mobile ions within the PEM has been proposed and discussed.
Y1  - 2013
U6  - http://dx.doi.org/10.1007/s00216-013-6951-9
SN  - 1432-1130 ; 1618-2642
VL  - 405
IS  - 20
SP  - 6425
EP  - 6436
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Werner, Frederik
A1  - Wagner, Torsten
A1  - Yoshinobu, Tatsuo
A1  - Keusgen, Michael
A1  - Schöning, Michael Josef
T1  - Frequency behaviour of light-addressable potentiometric sensors
JF  - Physica Status Solidi (A)
N2  - Light-addressable potentiometric sensors (LAPS) are semiconductor-based potentiometric sensors, with the advantage to detect the concentration of a chemical species in a liquid solution above the sensor surface in a spatially resolved manner. The addressing is achieved by a modulated and focused light source illuminating the semiconductor and generating a concentration-depending photocurrent. This work introduces a LAPS set-up that is able to monitor the electrical impedance in addition to the photocurrent. The impedance spectra of a LAPS structure, with and without illumination, as well as the frequency behaviour of the LAPS measurement are investigated. The measurements are supported by electrical equivalent circuits to explain the impedance and the LAPS-frequency behaviour. The work investigates the influence of different parameters on the frequency behaviour of the LAPS. Furthermore, the phase shift of the photocurrent, the influence of the surface potential as well as the changes of the sensor impedance will be discussed.
Y1  - 2013
U6  - http://dx.doi.org/10.1002/pssa.201200929
SN  - 1521-396X ; 0031-8965
VL  - 210
IS  - 5
SP  - 884
EP  - 891
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Itabashi, Akinori
A1  - Kosaka, Naoki
A1  - Miyamoto, Ko-ichiro
A1  - Wagner, Torsten
A1  - Schöning, Michael Josef
T1  - High-speed chemical imaging system based on front-side-illuminated LAPS
JF  - Sensors and actuators B: Chemical
N2  - The chemical imaging sensor is a semiconductor-based chemical sensor that can visualize the spatial distribution of specific ions on the sensing surface. The conventional chemical imaging system based on the light-addressable potentiometric sensor (LAPS), however, required a long time to obtain a chemical image, due to the slow mechanical scan of a single light beam. For high-speed imaging, a plurality of light beams modulated at different frequencies can be employed to measure the ion concentrations simultaneously at different locations on the sensor plate by frequency division multiplex (FDM). However, the conventional measurement geometry of back-side illumination limited the bandwidth of the modulation frequency required for FDM measurement, because of the low-pass filtering characteristics of carrier diffusion in the Si substrate. In this study, a high-speed chemical imaging system based on front-side-illuminated LAPS was developed, which achieved high-speed spatiotemporal recording of pH change at a rate of 70 frames per second.
Y1  - 2013
U6  - http://dx.doi.org/10.1016/j.snb.2013.03.016
SN  - 1873-3077
VL  - 182
SP  - 315
EP  - 321
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Feucht, Nikolaus
A1  - Schönbach, Etienne Michael
A1  - Lanzl, Ines
A1  - Kotliar, Konstantin
A1  - Lohmann, Chris Patrick
A1  - Maier, Mathias
T1  - Changes in the foveal microstructure after intravitreal bevacizumab application in patients with retinal vascular disease
JF  - Clinical Ophthalmology
Y1  - 2013
SN  - 1177-5483
VL  - 7
SP  - 173
EP  - 178
PB  - Dove Medical Press
CY  - Auckland, New Zealand
ER  - 
TY  - JOUR
A1  - Kotliar, Konstantin
A1  - Hanssen, Henner
A1  - Eberhardt, Karla
A1  - Vilser, Walthard
A1  - Schmaderer, Christoph
A1  - Halle, Martin
A1  - Heemann, Uwe
A1  - Baumann, M.
T1  - Retinal pulse wave velocity in young male normotensive and mildly hypertensive subjects
JF  - Microcirculation
Y1  - 2013
SN  - 1549-8719
N1  - Accepted Article (Accepted, unedited articles published online and citable. The final edited and typeset version of record will appear in future.)
PB  - Wiley
CY  - Malden
ER  - 
TY  - JOUR
A1  - Reisert, Steffen
A1  - Schneider, Benno
A1  - Geissler, Hanno
A1  - Gompel, Matthias van
A1  - Wagner, Patrick
A1  - Schöning, Michael Josef
T1  - Multi-sensor chip for the investigation of different types of metal oxides for the detection of H2O2 in the ppm range
JF  - physica status solidi (a)
N2  - In this work, a multi-sensor chip for the investigation of the sensing properties of different types of metal oxides towards hydrogen peroxide in the ppm range is presented. The fabrication process and physical characterization of the multi-sensor chip are described. Pure SnO2 and WO3 as well as Pd- and Pt-doped SnO2 films are characterized in terms of their sensitivity to H2O2. The sensing films have been prepared by drop-coating of water-dispensed nano-powders. A physical characterization, including scanning electron microscopy and X-ray diffraction analysis of the deposited metal-oxide films, was done. From the measurements in hydrogen peroxide atmosphere, it could be shown, that all of the tested metal oxide films are suitable for the detection of H2O2 in the ppm range. The highest sensitivity and reproducibility was achieved using Pt-doped SnO2.

Calibration plot of a SnO2, WO3, Pt-, and Pd-doped SnO2 gas sensor for H2O2 concentrations in the ppm range.
Y1  - 2013
SN  - 1862-6319
VL  - 210
IS  - 5
SP  - 898
EP  - 904
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Hennemann, Jörg
A1  - Kohl, Claus-Dieter
A1  - Reisert, Steffen
A1  - Kirchner, Patrick
A1  - Schöning, Michael Josef
T1  - Copper oxide nanofibres for detection of hydrogen peroxide vapour at high concentrations
JF  - physica status solidi (a)
N2  - We present a sensor concept based on copper(II)oxide (CuO) nanofibres for the detection of hydrogen peroxide (H2O2) vapour in the percent per volume (% v/v) range. The fibres were produced by using the electrospinning technique. To avoid water condensation in the pores, the fibres were initially modified by an exposure to H2S to get an enclosed surface. By a thermal treatment at 350 °C the fibres were oxidised back to CuO. Thereby, the visible pores disappear which was verified by SEM analysis. The fibres show a decrease of resistance with increasing H2O2  concentration which is due to the fact that hydrogen peroxide is an oxidising gas and CuO a p-type semiconductor. The sensor shows a change of resistance within the minute range to the exposure until the maximum concentration of 6.9% v/v H2O2. At operating temperatures below 450 °C the corresponding sensor response to a concentration of 4.1% v/v increases. The sensor shows a good reproducibility of the signal at different measurements. CuO seems to be a suitable candidate for the detection of H2O2 vapour at high concentrations.

Resistance behaviour of the sensor under exposure to H2O2 vapours between 2.3 and 6.9% v/v at an operating temperature of 450 °C.
Y1  - 2013
U6  - http://dx.doi.org/10.1002/pssa.201200775
SN  - 1862-6319
VL  - 210
IS  - 5
SP  - 859
EP  - 863
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - THES
A1  - Schieffer, Andre
T1  - Studies on diversity and coexistence in an experimental microbial community
N2  - Biodiversity and the coexistence of species have puzzled and fascinated biologists since decades and is a hotspot in todays’ natural sciences. Preserving this biodiversity is a great challenge as habitats and environments underlying tremendous changes like climate change and the loss of natural habitats, which are mainly due to anthropogenic influences. The coexistence of numerous species even in homogeneous environments is a stunning feature of natural communities and has been summarized under the term ‘paradox of plankton’. Up to now, there are several mechanisms discussed, which may contribute to local and global diversity of organisms. Several interspecific trade offs have been identified maintaining the coexistence of species like their abilities regarding competition and predator avoidance, their capability to disperse in space and time, and their ability to exploit variable resources. Further, micro-evolutionary dynamics supporting the coexistence of species have been added to our knowledge, and deriving from theoretical deterministic models, non-linear dynamics which describe the temporal fluctuation of abundances of organisms. Whereas competition and predation seem to be clue structural elements within interacting organisms, the intrinsic dynamic behavior – by means of temporal changes in abundance - plays an important role regarding coexistence within a community. The present work sheds light on different factors affecting the coexistence of species using experimental microbial model systems consisting of a bacterivorous ciliate as the predator and two bacteria strains as prey organism. Additionally, another experimental setup consisting of two up to five bacteria species competing for one limiting resource was investigated. Highly controllable chemostat systems were established to exclude extrinsic disturbances. According to theoretical analyses I was able to show - experimentally and theoretically - that phenotypic plasticity of one species within a microbial one-predator-two-prey food web enlarges the range of possible coexistence of all species under different dynamic conditions, compared to a food web without phenotypic plasticity. This was accompanied by non-linear (chaotic) population dynamics within all experimental systems showing phenotypic plasticity. The experiments on the interplay of competition, predation and invasion showed that all aspects have an influence on species coexistence. Under undisturbed controlled conditions all aspects were analyzed in detail and in combination. Populations showed oscillations which were shown by quasi-chaotic attractors in phase space diagrams. Competition experiments with two up to five bacteria species competing for one limiting resource showed that all organisms were able to coexist which was mediated by species oscillations entering a regime of chaos. Besides that fact it was found, that the productivity (biomass) as well as the total cell numbers – under the same nutrition supply – increased by an increasing number of species in the experimental systems. Up to now, the occurrence of non-linear dynamics in well controlled experimental studies has been recognized several times and this phenomenon seemed to be more common in natural systems than generally assumed.
N2  - Biodiversität und die Koexistenz von Arten fasziniert und verblüfft Biologen seit Jahr-zehnten und stellen einen Schwerpunkt in der heutigen Umweltforschung dar. Der Schutz und die Konservierung dieser Mannigfaltigkeit stellen eine große Herausfor-derung dar, da die natürlichen Lebensräume sowie die Umwelt enormen Verände-rungen unterworfen sind, welche meist in einem anthropogenen Ursprung wurzeln. Die Koexistenz vieler Arten, auch in relativ homogenen Habitaten ist ein faszinieren-des Charakteristikum natürlicher Lebensgemeinschaften und wird als ‚Paradox des Planktons‘ bezeichnet. Gegenwärtig werden diverse Ursachen diskutiert, welche vermutlich zur lokalen und globalen Diversität von Organismen beitragen. Einige die-ser möglichen Ursachen, die zur Aufrechterhaltung der Koexistenz der Arten beitra-gen, wurden identifiziert: Das Vermögen der Konkurrenz- und Prädationsvermeidung, die Fähigkeit räumlicher sowie zeitlicher Verteilung, sowie das Vermögen variable Ressourcen zu nutzen. Des Weiteren wurden mikro-evolutionäre Phänomene und Dynamiken identifiziert, sowie, von theoretischen deterministischen Modellen ausge-hend, nichtlineare Dynamiken, welche die zeitlichen Schwankungen der Abundanzen von Organismen beschreiben. Diese Aspekte stellen die Schlüsselkomponenten zwi-schen interagierenden Organismen dar, wobei das intrinsiche, nicht lineare dynami-sche Verhalten in Form von zeitlichen Veränderungen in Abundanzen eine zusätzli-che entscheidende Rolle bezüglich der Koexistenz von Arten spielen kann. Einige dieser Aspekte wurden in der vorliegenden Arbeit untersucht. In Anlehnung an theoretische Analysen konnte experimentell sowie theoretisch gezeigt werden, dass phänotypische Plastizität in einer Bakterienart in einem mikrobiellen Ein-Räuber-zwei-Beute-Nahrungsgewebe den Bereich der möglichen Koexistenz unter sich än-dernden experimentellen Bedingungen (Änderungen der Durchflussraten der Chemostate) – im direkten Vergleich zu einem experimentellen Nahrungsgewebe ohne phänotypische Plastizität – erweitern kann. Dies wurde begleitet durch nicht lineare Abundanzschwankungen in den Populationen aller untersuchten Versuchs-ansätze. In weiteren Untersuchungen wurde das Zusammenspiel von Konkurrenz, Prädation und Invasion in einer experimentellen mikrobiellen Gemeinschaft untersucht. Unter kontrollierten Bedingungen konnten diese Aspekte detailliert untersucht werden und es konnten Aufschlüsse darüber gewonnen werden, welche Reaktionen (Interaktionen) innerhalb der untersuchten Gemeinschaften stattfinden. Im Versuchsverlauf wurden Veränderungen in den Abundanzen sowie chaotische Schwankungen der Zellzahlen festgestellt. In Konkurrenzexperimenten von zwei bis zu fünf um eine limitierende Ressource konkurrierende Bakterienarten konnte gezeigt werden, dass alle Arten – vermittelt durch chaotische Abundanzschwankungen – nebeneinander koexistieren konnten. Begleitend dazu wurde herausgefunden, dass die Produktivität (Biomasse) sowie die Gesamtzellzahl bei gleicher Nahrungsverfügbarkeit der experimentellen Systeme mit steigender Artenzahl zunehmen. Gegenwärtig ist das Auftreten von Chaos in gut kontrollierten experimentellen Studien vereinzelt beobachtet worden, wobei dieses Phänomen jedoch häufiger in der Natur aufzutreten scheint als generell vermutet.
Y1  - 2012
N1  - Köln, Univ., Diss., 2012
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  - Heinzel, Alexander
A1  - Schäfer, Ralf
A1  - Müller, Hans-Wilhelm
A1  - Schieffer, Andre
A1  - Ingenhag, Ariane
A1  - Northoff, Georg
A1  - Franz, Matthias
A1  - Hautzel, Hubertus
T1  - Differential modulation of valence and arousal in high-alexithymic and low-alexithymic individuals
JF  - Neuroreport
N2  - High-alexithymic individuals are characterized by an impaired ability to identify and communicate emotions whereas low-alexithymic individuals have a wide-ranging ability to deal with emotions. This study examined the hypothesis that valence and arousal modifications of emotional stimuli differentially modulate cortical regions in high-alexithymic and low-alexithymic individuals. To this end, 28 high-alexithymic and 25 low-alexithymic individuals were investigated with event-related fMRI using visual emotional stimuli. We found differential neural activations in the dorsal anterior cingulate, the insula and the amygdala. We suggest that these differences may account for the impaired ability of high-alexithymic individuals to appropriately handle emotional stimuli.
Y1  - 2010
U6  - http://dx.doi.org/10.1097/WNR.0b013e32833f38e0
SN  - 1473-558X
VL  - 21
IS  - 15
SP  - 998
EP  - 1002
PB  - Lippincott Williams & Wilkins
CY  - London
ER  - 
TY  - JOUR
A1  - Heinzel, Alexander
A1  - Schäfer, Ralf
A1  - Müller, Hans-Wilhelm
A1  - Schieffer, Andre
A1  - Ingenhag, Ariane
A1  - Eickhoff, Simon B.
A1  - Northoff, Georg
A1  - Franz, Matthias
A1  - Hautzel, Hubertus
T1  - Increased Activation of the Supragenual Anterior Cingulate Cortex during Visual Emotional Processing in Male Subjects with High Degrees of Alexithymia: An Event-Related fMRI Study
JF  - Psychotherapy and Psychosomatics
N2  - Background: One of the most prominent neurobiological models of alexithymia assumes an altered function of the anterior cingulate cortex (ACC) as the crucial neural correlate of alexithymia. So far functional imaging studies have yielded inconclusive results. Therefore, we tested this hypothesis in healthy alexithymics and nonalexithymics in an event-related fMRI study.
Methods: Thirty high- and 30 low-alexithymic right-handed male subjects (selected by the 20-item Toronto Alexithymia Scale, TAS-20) were investigated with event-related fMRI using a picture viewing paradigm. The stimuli consisted of happy, fearful and neutral facial expressions (Ekman-Friesen) as well as positive, negative and neutral pictures from the International Affective Picture System.
Results: Contrasting the high-alexithymic with the low-alexithymic group we observed increased activation of the supragenual ACC for different emotional valences as well as for different emotional stimuli. Moreover, there was a positive correlation of the ACC with the individual TAS-20 scores but no correlations with the individual Beck Depression Inventory scores. Additionally, there was no difference in activity of the amygdala. 
Conclusions: We demonstrated that the supragenual ACC is constantly activated more strongly in alexithymic subjects and that this activation is related to the symptoms of alexithymia and not to associated symptoms such as depression. Therefore, our findings support the hypothesis of an altered function of the ACC in alexithymia.
Y1  - 2010
U6  - http://dx.doi.org/10.1159/000320121
SN  - 0033-3190
VL  - 79
IS  - 6
SP  - 363
EP  - 370
PB  - Karger
CY  - Basel
ER  - 
TY  - JOUR
A1  - Kirchner, Patrick
A1  - Oberländer, Jan
A1  - Suso, Henri-Pierre
A1  - Rysstad, Gunnar
A1  - Keusgen, Michael
A1  - Schöning, Michael Josef
T1  - Towards a wireless sensor system for real-time H2O2 monitoring in aseptic food processes
JF  - Physica status solidi (a)
N2  - A wireless sensor system based on the industrial ZigBee standard for low-rate wireless networking was developed that enables real-time monitoring of gaseous H2O2 during the package sterilization in aseptic food processes. The sensor system consists of a remote unit connected to a calorimetric gas sensor, which was already established in former works, and an external base unit connected to a laptop computer. The remote unit was built up by an XBee radio frequency (RF) module for data communication and a programmable system-on-chip controller to read out the sensor signal and process the sensor data, whereas the base unit is a second XBee RF module. For the rapid H2O2 detection on various locations inside the package that has to be sterilized, a novel read-out strategy of the calorimetric gas sensor was established, wherein the sensor response is measured within the short sterilization time and correlated with the present H2O2 concentration. In an exemplary measurement application in an aseptic filling machinery, the suitability of the new, wireless sensor system was demonstrated, wherein the influence of the gas velocity on the H2O2 distribution inside a package was determined and verified with microbiological tests.
KW  - calorimetric gas sensor;hydrogen peroxide;wireless sensor system
Y1  - 2013
U6  - http://dx.doi.org/10.1002/pssa.201200920
SN  - 1862-6319
VL  - 210
IS  - 5
SP  - 877
EP  - 883
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - CHAP
A1  - Duong, Minh Tuan
A1  - Nguyen, Nhu Hunyh
A1  - Staat, Manfred
T1  - Finite Element Implementation of a 3D Fung-type Model
T2  - ESMC-2012 - 8th European Solid Mechanics Conference, Graz, Austria, July 9-13, 2012
Y1  - 2012
SN  - 978-3-85125-223-1
PB  - Verlag d. Technischen Universität Graz
CY  - Graz
ER  - 
TY  - CHAP
A1  - Frotscher, Ralf
A1  - Raatschen, Hans-Jürgen
A1  - Staat, Manfred
ED  - Holzapfel, Gerhard A.
T1  - Effectiveness of the edge-based smoothed finite element method applied to soft biological tissues
T2  - ESMC-2012 - 8th European Solid Mechanics Conference, Graz, Austria, July 9-13, 2012
Y1  - 2012
SN  - 978-3-85125-223-1
PB  - Verlag d. Technischen Universität Graz
CY  - Graz
ER  - 
TY  - CHAP
A1  - Streun, M.
A1  - Al-Kaddoum, R.
A1  - Parl, C.
A1  - Pietrzyk, U.
A1  - Ziemons, Karl
A1  - Waasen, S. van
T1  - Simulation studies of optical photons in monolithic block scintillators
T2  - 2011 IEEE Nuclear Science Symposium Conference Record (NSS/MIC)
N2  - The interest in PET detectors with monolithic block scintillators is growing. In order to obtain high spatial resolutions dedicated positioning algorithms are required. But even an ideal algorithm can only deliver information which is provided by the detector. In this simulation study we investigated the light distribution on one surface of cuboid LSO scintillators of different size. Scintillators with a large aspect ratio (small footprint and large height) showed significant position information only for a minimum interaction depth of the gamma particle. The results allow a quantitative estimate for a useful aspect ratio.
Y1  - 2012
SN  - 978-1-4673-0120-6 (electronic ISBN)
SN  - 978-1-4673-0118-3 (print ISBN)
U6  - http://dx.doi.org/10.1109/NSSMIC.2011.6154621
SP  - 1380
EP  - 1382
PB  - IEEE
CY  - New York
ER  - 
TY  - JOUR
A1  - Parl, C.
A1  - Larue, H.
A1  - Streun, M.
A1  - Ziemons, Karl
T1  - Double-side-readout technique for SiPM-matrices
JF  - 2010 IEEE Nuclear Science Symposium Conference Record (NSS/MIC)
N2  - In our case the double-side-method is used to minimize the complexity of a matrix-readout. Here the number of channels is reduced to 2√N̅. It is also possible to benefit from the method in a single pixel readout system. One signal can be used to measure position and energy of the event, the other one can be applied to a fast trigger-circuit at the same time. In a next step we will investigate timing behavior and electrical crosstalk of the circuit.
Y1  - 2011
SN  - 1095-7863
SP  - 1486
EP  - 1487
PB  - IEEE
CY  - New York
ER  - 
TY  - JOUR
A1  - Herzog, Hans
A1  - Pietrzyk, Uwe
A1  - Shah, N. Jon
A1  - Ziemons, Karl
T1  - The current state, challenges and perspectives of MR-PET
JF  - Neuroimage
N2  - Following the success of PET/CT during the last decade and the recent increasing proliferation of SPECT/CT, another hybrid imaging instrument has been gaining more and more interest: MR-PET. First combined, simultaneous PET and MR studies carried out in small animals demonstrated the feasibility of the new approach. Concurrently, some prototypes of an MR-PET scanner for simultaneous human brain studies have been built, their performance is being tested and preliminary applications have already been shown. Through this pioneering work, it has become clear that advances in the detector design are necessary for further optimization.

Recently, the different issues related to the present state and future prospects of MR-PET were presented and discussed during an international 2-day workshop at the Forschungszentrum Jülich, Germany, held after, and in conjunction with, the 2008 IEEE Nuclear Science Symposium and Medical Imaging Conference in Dresden, Germany on October 27–28, 2008. The topics ranged from small animal MR-PET imaging to human MR-BrainPET imaging, new detector developments, challenges/opportunities for ultra-high field MR-PET imaging and considerations of possible future research and clinical applications. This report presents a critical summary of the contributions made to the workshop.
Y1  - 2010
U6  - http://dx.doi.org/10.1016/j.neuroimage.2009.10.036
SN  - 1053-8119
VL  - 49
IS  - 3
SP  - 2072
EP  - 2082
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Beer, S.
A1  - Streun, M.
A1  - Hombach, T.
A1  - Buehler, J.
A1  - Jahnke, S.
A1  - Khodaverdi, M.
A1  - Larue, H.
A1  - Minwuyelet, S.
A1  - Parl, C.
A1  - Roeb, G.
A1  - Schurr, U.
A1  - Ziemons, Karl
T1  - Design and initial performance of PlanTIS: a high-resolution positron emission tomograph for plants
JF  - Physics in Medicine and Biology
N2  - Positron emitters such as 11C, 13N and 18F and their labelled compounds are widely used in clinical diagnosis and animal studies, but can also be used to study metabolic and physiological functions in plants dynamically and in vivo. A very particular tracer molecule is 11CO2 since it can be applied to a leaf as a gas. We have developed a Plant Tomographic Imaging System (PlanTIS), a high-resolution PET scanner for plant studies. Detectors, front-end electronics and data acquisition architecture of the scanner are based on the ClearPET™ system. The detectors consist of LSO and LuYAP crystals in phoswich configuration which are coupled to position-sensitive photomultiplier tubes. Signals are continuously sampled by free running ADCs, and data are stored in a list mode format. The detectors are arranged in a horizontal plane to allow the plants to be measured in the natural upright position. Two groups of four detector modules stand face-to-face and rotate around the field-of-view. This special system geometry requires dedicated image reconstruction and normalization procedures. We present the initial performance of the detector system and first phantom and plant measurements.
Y1  - 2010
U6  - http://dx.doi.org/10.1088/0031-9155/55/3/006
SN  - 1361-6560
VL  - 55
IS  - 3
SP  - 635
EP  - 646
PB  - IOP
CY  - Bristol
ER  - 
TY  - JOUR
A1  - Streun, M.
A1  - Larue, H.
A1  - Parl, C.
A1  - Ziemons, Karl
T1  - A compact PET detector readout using charge-to-time conversion
JF  - 2009 IEEE Nuclear Science Symposium Conference Record (NSS/MIC)
N2  - The readout of gamma detectors is considerably simplified when the event intensity is encoded as a pulse width (Pulse Width Modulation, PWM). Time-to-Digital-Converters (TDC) replace the conventional ADCs and multiple TDCs can be realized easily in one PLD chip (Programmable Logic Device). The output of a PWM stage is only one digital signal per channel which is well suited for transport so that further processing can be performed apart from the detector. This is particularly interesting for large systems with high channel density (e.g. high resolution scanners). In this work we present a circuit with a linear transfer function that requires a minimum of components by performing the PWM already in the preamp stage. This allows a very compact and also cost-efficient implementation of the front-end electronics.
Y1  - 2009
SN  - 1082-3654
SP  - 1868
EP  - 1870
PB  - IEEE
CY  - New York
ER  - 
TY  - JOUR
A1  - Wedrowski, M.
A1  - Bruyndonckx, P.
A1  - Tavernier, S.
A1  - Zhi, L.
A1  - Dang, J.
A1  - Mendes, P. R.
A1  - Perez, J. M.
A1  - Ziemons, Karl
T1  - Robustness of neural networks algorithm for gamma detection in monolithic block detector, positron emission tomography
JF  - 2009 IEEE Nuclear Science Symposium Conference Record (NSS/MIC)
N2  - The monolithic scintillator block approach for gamma detection in the Positron Emission Tomography (PET) avoids estimating Depth of Interaction (DOI), reduces dead zones in detector and diminishes costs of detector production. Neural Networks (NN) are very efficient to determine the entrance point of a gamma incident on a scintillator block. This paper presents results on the robustness of the spatial resolution as a function of the random fraction in the data, temperature and HV fluctuations. This is important when implementing the method in a real scanner. Measurements were done with two Hamamatsu S8550 APD arrays, glued on a 20 × 20 × 10 mm3 monolithic LSO crystal block.
Y1  - 2009
SN  - 1082-3654
SP  - 2625
EP  - 2628
ER  - 
TY  - JOUR
A1  - Jahnke, Siegfried
A1  - Menzel, Marion I.
A1  - Dusschoten, Dagmar van
A1  - Roeb, Gerhard W.
A1  - Bühler, Jonas
A1  - Minwuyelet, Senay
A1  - Blümler, Peter
A1  - Temperton, Vicky M.
A1  - Hombach, Thomas
A1  - Streun, Matthias
A1  - Beer, Simone
A1  - Khodaverdi, Maryam
A1  - Ziemons, Karl
A1  - Coenen, Heinz H.
A1  - Schurr, Ulrich
T1  - Combined MRI–PET dissects dynamic changes in plant structures and functions
JF  - The Plant Journal
N2  - Unravelling the factors determining the allocation of carbon to various plant organs is one of the great challenges of modern plant biology. Studying allocation under close to natural conditions requires non-invasive methods, which are now becoming available for measuring plants on a par with those developed for humans. By combining magnetic resonance imaging (MRI) and positron emission tomography (PET), we investigated three contrasting root/shoot systems growing in sand or soil, with respect to their structures, transport routes and the translocation dynamics of recently fixed photoassimilates labelled with the short-lived radioactive carbon isotope 11C. Storage organs of sugar beet (Beta vulgaris) and radish plants (Raphanus sativus) were assessed using MRI, providing images of the internal structures of the organs with high spatial resolution, and while species-specific transport sectoralities, properties of assimilate allocation and unloading characteristics were measured using PET. Growth and carbon allocation within complex root systems were monitored in maize plants (Zea mays), and the results may be used to identify factors affecting root growth in natural substrates or in competition with roots of other plants. MRI–PET co-registration opens the door for non-invasive analysis of plant structures and transport processes that may change in response to genomic, developmental or environmental challenges. It is our aim to make the methods applicable for quantitative analyses of plant traits in phenotyping as well as in understanding the dynamics of key processes that are essential to plant performance.
Y1  - 2009
SN  - 1365-313X
VL  - 59
IS  - 4
SP  - 634
EP  - 644
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Ziemons, Karl
A1  - Bruyndonckx, P.
A1  - Perez, J. M.
A1  - Pietrzyk, U.
A1  - Rato, P.
A1  - Tavernier, S.
T1  - Beyond ClearPET: Next Aims
JF  - 5th IEEE International Symposium on Biomedical Imaging: From Nano to Macro Symposium Proceedings ISBI 2008
N2  - The CRYSTAL CLEAR collaboration, in short CCC, is a consortium of 12 academic institutions, mainly from Europe, joining efforts in the area of developing instrumentation for nuclear medicine and medical imaging. In the framework of the CCC a high performance small animal PET system, called ClearPET, was developed by using new technologies in electronics and crystals in a phoswich arrangement combining two types of lutetium- based scintillator materials: LSO:Ce and LuYAP:Ce. Our next aim will be the development of hybrid image systems. Hybrid MR-PET imaging has many unique advantages for brain research. This has sparked a new research line within CCC for the development of novel MR-PET compatible technologies. MRI is not as sensitive as PET but PET has poorer spatial resolution than MRI. Two major advantages of PET are sensitivity and its ability to acquire metabolic information. To assess these innovations, the development of a 9.4T hybrid animal MR-PET scanner is proposed based on an existing 9.4T MR scanner that will be adapted to enable simultaneous acquisition of MR and PET data using cutting- edge technology for both MR and PET.
Y1  - 2008
SN  - 978-1-4244-2003-2
SP  - 1421
EP  - 1424
ER  - 
TY  - JOUR
A1  - Streun, M.
A1  - Beer, S.
A1  - Hombach, T.
A1  - Jahnke, S.
A1  - Khodaverdi, M.
A1  - Larue, H.
A1  - Minwuyelet, S.
A1  - Parl, C.
A1  - Roeb, G.
A1  - Schurr, U.
A1  - Ziemons, Karl
T1  - PlanTIS: A positron emission tomograph for imaging 11C transport in plants
JF  - 2007 IEEE Nuclear Science Symposium Conference Record, Vol. 6
N2  - Plant growth and transport processes are highly dynamic. They are characterized by plant-internal control processes and by strong interactions with the spatially and temporally varying environment. Analysis of structure- function relations of growth and transport in plants will strongly benefit from the development of non-invasive techniques. PlanTIS (Plant Tomographic Imaging System) is designed for non-destructive 3D-imaging of positron emitting radiotracers. It will permit functional analysis of the dynamics of carbon distribution in plants including bulky organs. It will be applicable for screening transport properties of plants to evaluate e.g. temperature adaptation of genetically modified plants. PlanTIS is a PET scanner dedicated to monitor the dynamics of the 11C distribution within a plant while or after assimilation of 11CO2. Front end electronics and data acquisition architecture of the scanner are based on the ClearPETTM system [1]. Four detector modules form one of two opposing detector blocks. Optionally, a hardware coincidence detection between the blocks can be applied. In general the scan duration is rather long (~ 1 hour) compared to the decay time of 11C (20 min). As a result the count rates can vary over a wide range and accurate dead time correction is necessary.
Y1  - 2008
SN  - 1082-3654
SP  - 4110
EP  - 4112
ER  - 
TY  - JOUR
A1  - Mosset, J.-B.
A1  - Devroede, O.
A1  - Krieguer, M.
A1  - Rey, M.
A1  - Vieira, J.-M.
A1  - Jung, J. H.
A1  - Kuntner, C.
A1  - Streun, M.
A1  - Ziemons, Karl
A1  - Auffray, E.
A1  - Sempere-Roldan, P.
A1  - Lecoq, P.
A1  - Bruyndonckx, P.
A1  - Loude, J.-F.
A1  - Tavernier, S.
A1  - Morcel, C.
T1  - Development of an optimized LSO/LuYAP phoswich detector head for the Lausanne ClearPET demonstrator
JF  - IEEE Transactions on Nuclear Science
N2  - This paper describes the LSO/LuYAP phoswich detector head developed for the ClearPET small animal PET scanner demonstrator that is under construction in Lausanne within the Crystal Clear Collaboration. The detector head consists of a dual layer of 8×8 LSO and LuYAP crystal arrays coupled to a multi-anode photomultiplier tube (Hamamatsu R7600-M64). Equalistion of the LSO/LuYAP light collection is obtained through partial attenuation of the LSO scintillation light using a thin aluminum deposit of 20-35 nm on LSO and appropriate temperature regulation of the phoswich head between 30°C to 60°C. At 511keV, typical FWHM energy resolutions of the pixels of a phoswich head amounts to (28±2)% for LSO and (25±2)% for LuYAP. The LSO versus LuYAP crystal identification efficiency is better than 98%. Six detector modules have been mounted on a rotating gantry. Axial and tangential spatial resolutions were measured up to 4 cm from the scanner axis and compared to Monte Carlo simulations using GATE. FWHM spatial resolution ranges from 1.3 mm on axis to 2.6 mm at 4 cm from the axis.
Y1  - 2006
SN  - 0018-9499
VL  - 53
IS  - 1
SP  - 25
EP  - 29
ER  - 
TY  - JOUR
A1  - Khodaverdi, M.
A1  - Weber, S.
A1  - Streun, M.
A1  - Parl, C.
A1  - Ziemons, Karl
T1  - High resolution imaging with ClearPET™ Neuro - first animal images
JF  - 2005 IEEE Nuclear Science Symposium Conference Record, Vol. 3
N2  - The ClearPET™ Neuro is the first full ring scanner within the Crystal Clear Collaboration (CCC). It consists of 80 detector modules allocated to 20 cassettes. LSO and LuYAP:Ce crystals in phoswich configuration in combination with position sensitive photomultiplier tubes are used to achieve high sensitivity and realize the acquisition of the depth of interaction (DOI) information. The complete system has been tested concerning the mechanical and electronical stability and interplay. Moreover, suitable corrections have been implemented into the reconstruction procedure to ensure high image quality. We present first results which show the successful operation of the ClearPET™ Neuro for artefact free and high resolution small animal imaging. Based on these results during the past few months the ClearPET™ Neuro System has been modified in order to optimize the performance.
Y1  - 2006
SN  - 1082-3654
SP  - 1641
EP  - 1644
ER  - 
TY  - JOUR
A1  - Streun, M.
A1  - Brandenburg, G.
A1  - Khodaverdi, M.
A1  - Larue, H.
A1  - Parl, C.
A1  - Ziemons, Karl
T1  - Timemark correction for the ClearPET™ scanners
JF  - 2005 IEEE Nuclear Science Symposium Conference Record, Vol. 4
N2  - The small animal PET scanners developed by the Crystal Clear Collaboration (ClearPETtrade) detect coincidences by analyzing timemarks which are attached to each event. The scanners are able to save complete single list mode data which allows analysis and modification of the timemarks after data acquisition. The timemarks are obtained from the digitally sampled detector pulses by calculating the baseline crossing of the rising edge of the pulse which is approximated as a straight line. But the limited sampling frequency causes a systematic error in the determination of the timemark. This error depends on the phase of the sampling clock at the time of the event. A statistical method that corrects these errors will be presented
Y1  - 2006
SN  - 1082-3654
SP  - 2057
EP  - 2060
ER  - 
TY  - JOUR
A1  - Streun, M.
A1  - Brandenburg, G.
A1  - Larue, H.
A1  - Parl, C.
A1  - Ziemons, Karl
T1  - The data acquisition system of ClearPET neuro - a small animal PET scanner
JF  - IEEE Transactions on Nuclear Science
N2  - The Crystal Clear Collaboration has developed a modular system for a small animal PET scanner (ClearPET). The modularity allows the assembly of scanners of different sizes and characteristics in order to satisfy the specific needs of the individual member institutions. The system performs depth of interaction detection by using a phoswich arrangement combining LSO and LuYAP scintillators which are coupled to Multichannel Photomultipliers (PMTs). For each PMT a free running 40 MHz ADC digitizes the signal and the complete scintillation pulse is sampled by an FPGA and sent with 20 MB/s to a PC for preprocessing. The pulse provides information about the gamma energy and the scintillator material which identifies the interaction layer. Furthermore, the exact pulse starting time is obtained from the sampled data. This is important as no hardware coincidence detection is implemented. All single events are recorded and coincidences are identified by software. The system in Jülich (ClearPET Neuro) is equipped with 10240 crystals on 80 PMTs. The paper will present an overview of the data acquisition system.
Y1  - 2006
SN  - 0018-9499
VL  - 53
IS  - 3
SP  - 700
EP  - 703
ER  - 
TY  - JOUR
A1  - Khodaverdi, M.
A1  - Chatziioannou, A. F.
A1  - Weber, S.
A1  - Ziemons, Karl
A1  - Halling, H.
A1  - Pietrzyk, U.
T1  - Investigation of different MicroCT scanner configurations by GEANT4 simulations
JF  - IEEE Transactions on Nuclear Science
N2  - This study has been performed to design the combination of the new ClearPET (ClearPET is a trademark of the Crystal Clear Collaboration), a small animal positron emission tomography (PET) system, with a micro-computed tomography (microCT) scanner. The properties of different microCT systems have been determined by simulations based on GEANT4. We will demonstrate the influence of the detector material and the X-ray spectrum on the obtained contrast. Four different detector materials (selenium, cadmium zinc telluride, cesium iodide and gadolinium oxysulfide) and two X-ray spectra (a molybdenum and a tungsten source) have been considered. The spectra have also been modified by aluminum filters of varying thickness. The contrast between different tissue types (water, air, brain, bone and fat) has been simulated by using a suitable phantom. The results indicate the possibility to improve the image contrast in microCT by an optimized combination of the X-ray source and detector material.
Y1  - 2005
SN  - 0018-9499
VL  - 52
IS  - 1
SP  - 188
EP  - 192
ER  - 
TY  - JOUR
A1  - Ziemons, Karl
A1  - Auffray, E.
A1  - Barbier, R.
A1  - Brandenburg, G.
A1  - Bruyndonckx, P.
T1  - The ClearPET™ project: Development of a 2nd generation high-performance small animal PET scanner
JF  - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
N2  - Second generation high-performance PET scanners, called ClearPET™1, have been developed by working groups of the Crystal Clear Collaboration (CCC). High sensitivity and high spatial resolution for the ClearPET camera is achieved by using a phoswich arrangement combining two different types of lutetium-based scintillator materials: LSO from CTI and LuYAP:Ce from the CCC (ISTC project). In a first ClearPET prototype, phoswich arrangements of 8×8 crystals of 2×2×10 mm3 are coupled to multi-channel photomultiplier tubes (Hamamatsu R7600). A unit of four PMTs arranged in-line represents one of 20 sectors of the ring design. The opening diameter of the ring is 120 mm, the axial detector length is 110 mm.The PMT pulses are digitized by free-running ADCs and digital data processing determines the gamma energy, the phoswich layer and even the exact pulse starting time, which is subsequently used for coincidence detection. The gantry allows rotation of the detector modules around the field of view.

Preliminary data shows a correct identification of the crystal layer about (98±1)%. Typically the energy resolution is (23.3±0.5)% for the luyap layer and (15.4±0.4)% for the lso layer. early studies showed the timing resolution of 2 ns FWHM and 4.8 ns FWTM. the intrinsic spatial resolution ranges from 1.37 mm to 1.61 mm full-width of half-maximum (FWHM) with a mean of 1.48 mm FWHM. further improvements in image and energy resolution are expected when the system geometry is fully modeled.
Y1  - 2005
SN  - 0168-9002
N1  - Proceedings of the 7th International Conference on Inorganic Scintillators and their Use in Scientific and Industrial Applications
VL  - 537
IS  - 1-2
SP  - 307
EP  - 311
ER  - 
TY  - JOUR
A1  - Streun, M.
A1  - Christ, D.
A1  - Hellendung, A.
A1  - Larue, H.
A1  - Ziemons, Karl
A1  - Halling, H.
T1  - Effects of crosstalk and gain nonuniformity using multichannel PMTs in the Clearpet® scanner
JF  - Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
N2  - The ClearPET® scanners developed by the Crystal Clear Collaboration use multichannel PMTs as photodetectors with scintillator pixels coupled individually to each channel. In order to localize an event each channel anode is connected to a comparator that triggers when the anode signal exceeds a common predefined threshold. Two major difficulties here are crosstalk of light and the gain nonuniformity of the PMT channels. Crosstalk can generate false triggering in channels adjacent to the actual event. On the one hand this can be suppressed by sufficiently increasing the threshold, but on the other hand a threshold too high can already prevent valid events on the lower gain channels from being detected. Finally, both effects restrict the dynamic range of pulse heights that can be processed. The requirements to the dynamic range are not low as the ClearPET® scanners detect the depth of interaction by phoswich pixels consisting of LSO and Lu0.7Y0.3AP, two scintillators with different light yields. We will present a model to estimate the achievable dynamic range and show solutions to increase it.
Y1  - 2005
SN  - 0168-9002
N1  - Proceedings of the 7th International Conference on Inorganic Scintillators and their Use in Scientific and Industrial Applications
VL  - 537
IS  - 1-2
SP  - 402
EP  - 405
ER  -