TY  - JOUR
A1  - Hoffmann, Andreas
A1  - Rohrbach, Felix
A1  - Uhl, Matthias
A1  - Ceblin, Maximilian
A1  - Bauer, Thomas
A1  - Mallah, Marcel
A1  - Jacob, Timo
A1  - Heuermann, Holger
A1  - Kuehne, Alexander J. C.
T1  - Atmospheric pressure plasma-jet treatment of polyacrylonitrile-nonwovens—Stabilization and roll-to-roll processing
JF  - Journal of Applied Polymer Science
N2  - Carbon nanofiber nonwovens represent a powerful class of materials with prospective application in filtration technology or as electrodes with high surface area in batteries, fuel cells, and supercapacitors. While new precursor-to-carbon conversion processes have been explored to overcome productivity restrictions for carbon fiber tows, alternatives for the two-step thermal conversion of polyacrylonitrile precursors into carbon fiber nonwovens are absent. In this work, we develop a continuous roll-to-roll stabilization process using an atmospheric pressure microwave plasma jet. We explore the influence of various plasma-jet parameters on the morphology of the nonwoven and compare the stabilized nonwoven to thermally stabilized samples using scanning electron microscopy, differential scanning calorimetry, and infrared spectroscopy. We show that stabilization with a non-equilibrium plasma-jet can be twice as productive as the conventional thermal stabilization in a convection furnace, while producing electrodes of comparable electrochemical performance.
KW  - batteries and fuel cells
KW  - electrospinning
KW  - fibers
KW  - irradiation
KW  - porous materials
Y1  - 2022
U6  - http://dx.doi.org/10.1002/app.52887
SN  - 0021-8995 (Print)
SN  - 1097-4628 (Online)
N1  - Weitere Informationen: Bundesministerium für Bildung und Forschung, Fördernummer: 13XP5036E. Deutsche Forschungsgemeinschaft, Fördernummern: 390874152, 441209207, 327886311
VL  - 139
IS  - 37
SP  - 1
EP  - 9
PB  - Wiley
ER  - 
TY  - JOUR
A1  - Fiedler, Thomas M.
A1  - Orzada, Stephan
A1  - Flöser, Martina
A1  - Rietsch, Stefan H. G.
A1  - Schmidt, Simon
A1  - Stelter, Jonathan K.
A1  - Wittrich, Marco
A1  - Quick, Harald H.
A1  - Bitz, Andreas
A1  - Ladd, Mark E.
T1  - Performance and safety assessment of an integrated transmitarray for body imaging at 7 T under consideration of specificabsorption rate, tissue temperature, and thermal dose
JF  - NMR in Biomedicine
N2  - In this study, the performance of an integrated body-imaging array for 7 T with 32 radiofrequency (RF) channels under consideration of local specific absorption rate (SAR), tissue temperature, and thermal dose limits was evaluated and the imaging performance was compared with a clinical 3 T body coil.

Thirty-two transmit elements were placed in three rings between the bore liner and RF shield of the gradient coil. Slice-selective RF pulse optimizations for B1 shimming and spokes were performed for differently oriented slices in the body under consideration of realistic constraints for power and local SAR. To improve the B1+ homogeneity, safety assessments based on temperature and thermal dose were performed to possibly allow for higher input power for the pulse optimization than permissible with SAR limits.

The results showed that using two spokes, the 7 T array outperformed the 3 T birdcage in all the considered regions of interest. However, a significantly higher SAR or lower duty cycle at 7 T is necessary in some cases to achieve similar B1+ homogeneity as at 3 T. The homogeneity in up to 50 cm-long coronal slices can particularly benefit from the high RF shim performance provided by the 32 RF channels. The thermal dose approach increases the allowable input power and the corresponding local SAR, in one example up to 100 W/kg, without limiting the exposure time necessary for an MR examination.

In conclusion, the integrated antenna array at 7 T enables a clinical workflow for body imaging and comparable imaging performance to a conventional 3 T clinical body coil.
KW  - body imaging at 7 T MRI
KW  - thermal dose
KW  - tissue temperature
KW  - transmit antenna arrays
Y1  - 2022
U6  - http://dx.doi.org/10.1002/nbm.4656
SN  - 0952-3480 (Print)
SN  - 1099-1492 (Online)
VL  - 35
IS  - 5
SP  - 1
EP  - 17
PB  - Wiley
ER  - 
TY  - JOUR
A1  - Fagan, Andrew J.
A1  - Bitz, Andreas
A1  - Björkman-Burtscher, Isabella M.
A1  - Collins, Christopher M.
A1  - Kimbrell, Vera
A1  - Raaijmakers, Alexander J. E.
T1  - 7T MR Safety
JF  - Journal of Magnetic Resonance Imaging (JMRI)
Y1  - 2021
U6  - http://dx.doi.org/10.1002/jmri.27319
SN  - 1522-2586
VL  - 53
IS  - 2
SP  - 333
EP  - 346
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Rietsch, Stefan H. G.
A1  - Brunheim, Sascha
A1  - Orzada, Stephan
A1  - Voelker, Maximilian N.
A1  - Maderwald, Stefan
A1  - Bitz, Andreas
A1  - Gratz, Marcel
A1  - Ladd, Mark E.
A1  - Quick, Harald H.
T1  - Development and evaluation of a 16-channel receive-only RF coil to improve 7T ultra-high field body MRI with focus on the spine
JF  - Magnetic Resonance in Medicine
Y1  - 2019
U6  - http://dx.doi.org/10.1002/mrm.27731
SN  - 1522-2594
IS  - Early view
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Noureddine, Yacine
A1  - Kraff, Oliver
A1  - Ladd, Mark E.
A1  - Wrede, Karsten
A1  - Chen, Bixia
A1  - Quick, Harald H.
A1  - Schaefers, Georg
A1  - Bitz, Andreas
T1  - Radiofrequency induced heating around aneurysm clips using a generic birdcage head coil at 7 Tesla under consideration of the minimum distance to decouple multiple aneurysm clips
JF  - Magnetic Resonance in Medicine
Y1  - 2019
U6  - http://dx.doi.org/10.1002/mrm.27835
SN  - 1522-2594
IS  - Early view
SP  - 1
EP  - 17
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Noureddine, Yacine
A1  - Kraff, Oliver
A1  - Ladd, Mark E.
A1  - Wrede, Karsten H.
A1  - Chen, Bixia
A1  - Quick, Harald H.
A1  - Schaefers, Gregor
A1  - Bitz, Andreas
T1  - In vitro and in silico assessment of RF-induced heating around intracranial aneurysm clips at 7 Tesla
JF  - Magnetic Resonance in Medicine
Y1  - 2017
U6  - http://dx.doi.org/10.1002/mrm.26650
SN  - 1522-2594
IS  - Early view
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Rietsch, Stefan H. G.
A1  - Pfaffenrot, Viktor
A1  - Bitz, Andreas
A1  - Orzada, Stephan
A1  - Brunheim, Sascha
A1  - Lazik-Palm, Andrea
A1  - Theysohn, Jens M.
A1  - Ladd, Mark E.
A1  - Quick, Harald H.
A1  - Kraff, Oliver
T1  - An 8-channel transceiver 7-channel receive RF coil setup for high SNR ultrahigh-field MRI of the shoulder at 7T
JF  - Medical Physics
Y1  - 2017
U6  - http://dx.doi.org/10.1002/mp.12612
SN  - 0094-2405
IS  - Article in press
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Bank, Bart L. van de
A1  - Orzada, Stephan
A1  - Smits, Frits
A1  - Lagemaat, Miriam W.
A1  - Rodgers, Christopher T.
A1  - Bitz, Andreas
A1  - Scheenen, Tom W. J.
T1  - Optimized (31) P MRS in the human brain at 7 T with a dedicated RF coil setup
JF  - NMR in Biomedicine
Y1  - 2015
U6  - http://dx.doi.org/10.1002/nbm.3422
SN  - 1099-1492
VL  - 28
IS  - 11
SP  - 1570
EP  - 1578
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Lagemaat, Miriam W.
A1  - Maas, Marnix C.
A1  - Vos, Eline K.
A1  - Bitz, Andreas
A1  - Orzada, Stephan
A1  - Weiland, Elisabeth
A1  - Uden, Mark J. van
A1  - Kobus, Thiele
A1  - Heerschap, Arend
A1  - Scheenen, Tom W. J.
T1  - (31) P MR spectroscopic imaging of the human prostate at 7 T: T1 relaxation times, Nuclear Overhauser Effect, and spectral characterization
JF  - Magnetic Resonance in Medicine
Y1  - 2015
U6  - http://dx.doi.org/10.1002/mrm.25209
SN  - 1522-2594
VL  - 73
IS  - 3
SP  - 909
EP  - 920
PB  - Wiley
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Pöttgen, Philipp
A1  - Ederer, Thorsten
A1  - Altherr, Lena
A1  - Lorenz, Ulf
A1  - Pelz, Peter F.
T1  - Examination and optimization of a heating circuit for energy-efficient buildings
JF  - Energy Technology
N2  - The conference center darmstadtium in Darmstadt is a prominent example of energy efficient buildings. Its heating system consists of different source and consumer circuits connected by a Zortström reservoir. Our goal was to reduce the energy costs of the system as much as possible. Therefore, we analyzed its supply circuits. The first step towards optimization is a complete examination of the system: 1) Compilation of an object list for the system, 2) collection of the characteristic curves of the components, and 3) measurement of the load profiles of the heat and volume-flow demand. Instead of modifying the system manually and testing the solution by simulation, the second step was the creation of a global optimization program. The objective was to minimize the total energy costs for one year. We compare two different topologies and show opportunities for significant savings.
KW  - energy transfer
KW  - heating system
KW  - programming
KW  - system optimization
KW  - technical operations research
Y1  - 2015
SN  - 2194-4296
U6  - http://dx.doi.org/10.1002/ente.201500252
VL  - 4
IS  - 1
SP  - 136
EP  - 144
PB  - WILEY-VCH Verlag
CY  - Weinheim
ER  -