@article{BronderPoghossianKeusgenetal.2017, author = {Bronder, Thomas and Poghossian, Arshak and Keusgen, Michael and Sch{\"o}ning, Michael Josef}, title = {Label-free detection of double-stranded DNA molecules with polyelectrolyte-modified capacitive field-effect sensors}, series = {tm - Technisches Messen}, volume = {84}, journal = {tm - Technisches Messen}, number = {10}, publisher = {De Gruyter}, address = {Oldenbourg}, doi = {10.1515/teme-2017-0015}, pages = {628 -- 634}, year = {2017}, abstract = {In this study, polyelectrolyte-modified field-effect-based electrolyte-insulator-semiconductor (EIS) devices have been used for the label-free electrical detection of double-stranded deoxyribonucleic acid (dsDNA)molecules. The sensor-chip functionalization with a positively charged polyelectrolyte layer provides the possibility of direct adsorptive binding of negatively charged target DNA oligonucleotides onto theSiO2-chip surface.EIS sensors can be utilized as a tool to detect surface-charge changes; the electrostatic adsorption of oligonucleotides onto the polyelectrolyte layer leads to a measureable surface-potential change. Signals of 39mV have been recorded after the incubation with the oligonucleotide solution. Besides the electrochemical experiments, the successful adsorption of dsDNA onto the polyelectrolyte layer has been verified via fluorescence microscopy. The presented results demonstrate that the signal recording of EISchips, which are modified with a polyelectrolyte layer, canbe used as a favorable approach for a fast, cheap and simple detection method for dsDNA.}, language = {en} } @article{ArreolaOberlaenderMaetzkowetal.2017, author = {Arreola, Julio and Oberl{\"a}nder, Jan and M{\"a}tzkow, M. and Keusgen, Michael and Sch{\"o}ning, Michael Josef}, title = {Surface functionalization for spore-based biosensors with organosilanes}, series = {Electrochimica Acta}, volume = {241}, journal = {Electrochimica Acta}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0013-4686}, doi = {10.1016/j.electacta.2017.04.157}, pages = {237 -- 243}, year = {2017}, abstract = {In the present work, surface functionalization of different sensor materials was studied. Organosilanes are well known to serve as coupling agent for biomolecules or cells on inorganic materials. 3-aminopropyltriethoxysilane (APTES) was used to attach microbiological spores time to an interdigitated sensor surface. The functionality and physical properties of APTES were studied on isolated sensor materials, namely silicon dioxide (SiO2) and platinum (Pt) as well as the combined material on sensor level. A predominant immobilization of spores could be demonstrated on SiO2 surfaces. Additionally, the impedance signal of APTES-functionalized biosensor chips has been investigated.}, language = {en} } @article{BalzerStreit2017, author = {Balzer, Hermann and Streit, Daniel}, title = {Das Translationsrisiko multinationaler Konzerne in Deutschland: Eine explorative Analyse von Verst{\"a}ndnis, Bedeutung und Management-Praxis mit Hilfe der Critical Incident Technique}, series = {Schmalenbachs Zeitschrift f{\"u}r betriebswirtschaftliche Forschung}, journal = {Schmalenbachs Zeitschrift f{\"u}r betriebswirtschaftliche Forschung}, number = {Online first}, publisher = {Springer}, address = {Berlin}, issn = {2366-6153}, doi = {10.1007/s41471-017-0029-x}, pages = {1 -- 40}, year = {2017}, language = {de} } @article{HansenBitzStreckert1999, author = {Hansen, Volkert W. and Bitz, Andreas and Streckert, Joachim R.}, title = {RF Exposure of Biological Systems in Radial Waveguides}, series = {IEEE Transactions on Electromagnetic Compatibility}, volume = {41}, journal = {IEEE Transactions on Electromagnetic Compatibility}, number = {4}, issn = {1558-187X}, doi = {10.1109/15.809852}, pages = {487 -- 493}, year = {1999}, language = {en} } @article{SommerStreckertBitzetal.2004, author = {Sommer, Angela M. and Streckert, Joachim and Bitz, Andreas and Hansen, Volkert W. and Lerchl, Alexander}, title = {No effects of GSM-modulated 900 MHz electromagnetic fields on survival rate and spontaneous development of lymphoma in female AKR/J mice}, series = {BMC Cancer}, volume = {77}, journal = {BMC Cancer}, number = {4}, doi = {10.1186/1471-2407-4-77}, year = {2004}, language = {en} } @article{NdoumbeMbonjoMbonjoStreckertBitzetal.2004, author = {Ndoumb{\`e} Mbonjo Mbonjo, H. and Streckert, J. and Bitz, Andreas and Hansen, V. and Glasmachers, A. and Gencol, S. and Rozic, D.}, title = {Generic UMTS test signal for RF bioelectromagnetic studies}, series = {Bioelectromagnetics}, volume = {25}, journal = {Bioelectromagnetics}, number = {6}, issn = {1521-186X}, doi = {10.1002/bem.20007}, pages = {415 -- 425}, year = {2004}, language = {en} } @article{WissenBogdanskiScheeretal.2005, author = {Wissen, M. and Bogdanski, N. and Scheer, H.-C. and Bitz, Andreas and Ahrens, G. and Gruetzner, G.}, title = {Implication of the light polarisation for UV curing of pre-patterned resists}, series = {Microelectronic Engineering}, volume = {78-79}, journal = {Microelectronic Engineering}, issn = {0167-9317}, doi = {10.1016/j.mee.2004.12.099}, pages = {659 -- 664}, year = {2005}, language = {en} } @article{FrankeStreckertBitzetal.2005, author = {Franke, Helmut and Streckert, Joachim and Bitz, Andreas and Goeke, Johannes and Hansen, Volkert and Ringelstein, E. Bernd and Nattk{\"a}mper, Heiner and Galle, Hans-Joachim and St{\"o}gbauer, Florian}, title = {Effects of Universal Mobile Telecommunications System (UMTS) electromagnetic fields on the blood-brain barrier in vitro}, series = {Radiation Research}, volume = {164}, journal = {Radiation Research}, number = {3}, issn = {1938-5404}, doi = {10.1667/RR3424.1}, pages = {258 -- 269}, year = {2005}, language = {en} } @article{SukhotinaStreckertBitzetal.2006, author = {Sukhotina, Irina and Streckert, Joachim R. and Bitz, Andreas and Hansen, Volkert W. and Lerchl, Alexander}, title = {1800 MHz electromagnetic field effects on melatonin release from isolated pineal glands}, series = {Journal of Pineal Research}, volume = {40}, journal = {Journal of Pineal Research}, number = {1}, issn = {1600-079X}, doi = {10.1111/j.1600-079X.2005.00284.x}, pages = {86 -- 91}, year = {2006}, language = {en} } @article{SommerBitzStreckertetal.2007, author = {Sommer, Angela M. and Bitz, Andreas and Streckert, Joachim and Hansen, Volkert W. and Lerchl, Alexander}, title = {Lymphoma development in mice chronically exposed to UMTS-modulated radiofrequency electromagnetic fields}, series = {Radiation Research}, volume = {168}, journal = {Radiation Research}, number = {1}, issn = {1938-5404}, doi = {10.1667/RR0857.1}, pages = {72 -- 80}, year = {2007}, language = {en} } @article{ReinhardtBitzElOuardietal.2007, author = {Reinhardt, T. and Bitz, Andreas and El Ouardi, A. and Streckert, J. and Sommer, A. and Lerchl, A. and Hansen, V.}, title = {Exposure set-ups for in vivo experiments using radial waveguides}, series = {Radiation Protection Dosimetry}, volume = {124}, journal = {Radiation Protection Dosimetry}, number = {1}, issn = {1742-3406}, doi = {10.1093/rpd/ncm370}, pages = {21 -- 26}, year = {2007}, language = {en} } @article{LerchlKruegerNiehausetal.2008, author = {Lerchl, Alexander and Kr{\"u}ger, Heike and Niehaus, Michael and Streckert, Joachim R. and Bitz, Andreas and Hansen, Volkert}, title = {Effects of mobile phone electromagnetic fields at nonthermal SAR values on melatonin and body weight of Djungarian hamsters (Phodopus sungorus)}, series = {Journal of Pineal Research}, volume = {44}, journal = {Journal of Pineal Research}, number = {3}, issn = {1600-079X}, doi = {10.1111/j.1600-079X.2007.00522.x}, pages = {267 -- 272}, year = {2008}, language = {en} } @article{KlompBitzHeerschapetal.2009, author = {Klomp, D. W. J. and Bitz, Andreas and Heerschap, A. and Scheenen, T. W. J.}, title = {Proton spectroscopic imaging of the human prostate at 7 T}, series = {NMR in Biomedicine}, volume = {22}, journal = {NMR in Biomedicine}, number = {5}, issn = {1099-1492}, doi = {10.1002/nbm.1360}, pages = {495 -- 501}, year = {2009}, language = {en} } @article{SchlamannYoonMaderwaldetal.2009, author = {Schlamann, M. and Yoon, M.-S. and Maderwald, S. and Pietrzyk, T. and Bitz, Andreas and Gerwig, M. and Forsting, M. and Ladd, S. C. and Ladd, M. E. and Kastrup, O.}, title = {Auswirkungen der Magnetresonanztomografie auf die Elektrophysiologie des motorischen Kortex: eine Studie mit transkranieller Magnetstimulation}, series = {R{\"o}Fo - Fortschritte auf dem Giebiet der R{\"o}ntgenstrahlen und der bildgebenden Verfahren}, volume = {181}, journal = {R{\"o}Fo - Fortschritte auf dem Giebiet der R{\"o}ntgenstrahlen und der bildgebenden Verfahren}, number = {3}, publisher = {Thieme}, address = {Stuttgart}, issn = {1438-9029}, doi = {10.1055/s-0028-1109038}, pages = {215 -- 219}, year = {2009}, language = {de} } @article{KraffBitzKruszonaetal.2009, author = {Kraff, Oliver and Bitz, Andreas and Kruszona, Stefan and Orzada, Stephan and Schaefer, Lena C. and Theysohn, Jens M. and Maderwald, Stefan and Ladd, Mark E. and Quick, Harald H.}, title = {An eight-channel phased array RF coil for spine MR imaging at 7 T}, series = {Investigative Radiology}, volume = {44}, journal = {Investigative Radiology}, number = {11}, publisher = {Lippincott Williams \& Wilkins}, issn = {1536-0210}, doi = {10.1097/RLI.0b013e3181b24ab7}, pages = {734 -- 740}, year = {2009}, language = {en} } @article{SchlamannYoonMaderwaldetal.2010, author = {Schlamann, Marc and Yoon, Min-Suk and Maderwald, Stefan and Pietrzyk, Thomas and Bitz, Andreas and Gerwig, Marcus and Forsting, Michael and Ladd, Susanne C. and Ladd, Mark E. and Kastrup, Oliver}, title = {Short term effects of magnetic resonance imaging on excitability of the motor cortex at 1.5T and 7T}, series = {Academic Radiology}, volume = {17}, journal = {Academic Radiology}, number = {3}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1076-6332}, doi = {10.1016/j.acra.2009.10.004}, pages = {277 -- 281}, year = {2010}, abstract = {Rationale and Objectives The increasing spread of high-field and ultra-high-field magnetic resonance imaging (MRI) scanners has encouraged new discussion of the safety aspects of MRI. Few studies have been published on possible cognitive effects of MRI examinations. The aim of this study was to examine whether changes are measurable after MRI examinations at 1.5 and 7 T by means of transcranial magnetic stimulation (TMS). Materials and Methods TMS was performed in 12 healthy, right-handed male volunteers. First the individual motor threshold was specified, and then the cortical silent period (SP) was measured. Subsequently, the volunteers were exposed to the 1.5-T MRI scanner for 63 minutes using standard sequences. The MRI examination was immediately followed by another TMS session. Fifteen minutes later, TMS was repeated. Four weeks later, the complete setting was repeated using a 7-T scanner. Control conditions included lying in the 1.5-T scanner for 63 minutes without scanning and lying in a separate room for 63 minutes. TMS was performed in the same way in each case. For statistical analysis, Wilcoxon's rank test was performed. Results Immediately after MRI exposure, the SP was highly significantly prolonged in all 12 subjects at 1.5 and 7 T. The motor threshold was significantly increased. Fifteen minutes after the examination, the measured value tended toward normal again. Control conditions revealed no significant differences. Conclusion MRI examinations lead to a transient and highly significant alteration in cortical excitability. This effect does not seem to depend on the strength of the static magnetic field.}, language = {en} } @article{BitzZhouElQuardietal.2009, author = {Bitz, Andreas and Zhou, Yi and El Quardi, Abdessamad and Streckert, Joachim}, title = {Occupational Exposure at Mobile Communication Base Station Antenna Sites}, series = {Frequenz}, volume = {63}, journal = {Frequenz}, number = {7-8}, issn = {2191-6349}, doi = {10.1515/FREQ.2009.63.7-8.123}, pages = {123 -- 128}, year = {2009}, language = {en} } @article{SchlamannVoigtMaderwaldetal.2010, author = {Schlamann, Marc and Voigt, Melanie A. and Maderwald, Stefan and Bitz, Andreas and Kraff, Oliver and Ladd, Susanne C. and Ladd, Mark E. and Forsting, Michael and Wilhelm, Hans}, title = {Exposure to high-field MRI does not affect cognitive function}, series = {Journal of Magnetic Resonance Imaging}, volume = {31}, journal = {Journal of Magnetic Resonance Imaging}, number = {5}, publisher = {Wiley-Liss}, address = {New York}, issn = {1522-2586}, doi = {10.1002/jmri.22065}, pages = {1061 -- 1066}, year = {2010}, abstract = {Purpose To assess potential cognitive deficits under the influence of static magnetic fields at various field strengths some studies already exist. These studies were not focused on attention as the most vulnerable cognitive function. Additionally, mostly no magnetic resonance imaging (MRI) sequences were performed. Materials and Methods In all, 25 right-handed men were enrolled in this study. All subjects underwent one MRI examination of 63 minutes at 1.5 T and one at 7 T within an interval of 10 to 30 days. The order of the examinations was randomized. Subjects were referred to six standardized neuropsychological tests strictly focused on attention immediately before and after each MRI examination. Differences in neuropsychological variables between the timepoints before and after each MRI examination were assessed and P-values were calculated Results Only six subtests revealed significant differences between pre- and post-MRI. In these tests the subjects achieved better results in post-MRI testing than in pre-MRI testing (P = 0.013-0.032). The other tests revealed no significant results. Conclusion The improvement in post-MRI testing is only explicable as a result of learning effects. MRI examinations, even in ultrahigh-field scanners, do not seem to have any persisting influence on the attention networks of human cognition immediately after exposure.}, language = {en} } @article{ElQuardiStreckertBitzetal.2011, author = {El Quardi, A. and Streckert, J. and Bitz, Andreas and M{\"u}nkner, S. and Engel, J. and Hansen, V.}, title = {New fin-line devices for radiofrequency exposure of small biological samples in vitro allowing whole-cell patch clamp recordings}, series = {Bioelectromagnetics}, volume = {32}, journal = {Bioelectromagnetics}, number = {2}, publisher = {Wiley}, address = {Weinheim}, issn = {1521-186X}, doi = {10.1002/bem.20621}, pages = {102 -- 112}, year = {2011}, abstract = {The development and analysis of three waveguides for the exposure of small biological in vitro samples to mobile communication signals at 900 MHz (GSM, Global System for Mobile Communications), 1.8 GHz (GSM), and 2 GHz (UMTS, Universal Mobile Telecommunications System) is presented. The waveguides were based on a fin-line concept and the chamber containing the samples bathed in extracellular solution was placed onto two fins with a slot in between, where the exposure field concentrates. Measures were taken to allow for patch clamp recordings during radiofrequency (RF) exposure. The necessary power for the achievement of the maximum desired specific absorption rate (SAR) of 20 W/kg (average over the mass of the solution) was approximately Pin = 50 mW, Pin = 19 mW, and Pin = 18 mW for the 900 MHz, 1800 MHz, and 2 GHz devices, respectively. At 20 W/kg, a slight RF-induced temperature elevation in the solution of no more than 0.3 °C was detected, while no thermal offsets due to the electromagnetic exposure could be detected at the lower SAR settings (2, 0.2, and 0.02 W/kg). A deviation of 10\% from the intended solution volume yielded a calculated SAR deviation of 8\% from the desired value. A maximum ±10\% variation in the local SAR could occur when the position of the patch clamp electrode was altered within the area where the cells to be investigated were located.}, language = {en} } @article{KraffBitzBreyeretal.2011, author = {Kraff, Oliver and Bitz, Andreas and Breyer, Tobias and Kruszona, Stefan and Maderwald, Stefan and Brote, Irina and Gizewski, Elke R. and Ladd, Mark E. and Quick, Harald H.}, title = {A transmit/receive radiofrequency array for imaging the carotid arteries at 7 Tesla: coil design and first in vivo results}, series = {Investigative Radiology}, volume = {46}, journal = {Investigative Radiology}, number = {4}, publisher = {Wolters Kluwer}, address = {K{\"o}ln}, issn = {1536-0210}, doi = {10.1097/RLI.0b013e318206cee4}, pages = {246 -- 254}, year = {2011}, abstract = {Objective: To develop a transmit/receive radiofrequency (RF) array for magnetic resonance imaging (MRI) of the carotid arteries at 7 T. The prototype is characterized in numerical simulations and bench measurements, and the feasibility of plaque imaging at 7 T is demonstrated in first in vivo images. Materials and Methods: The RF phased array coil consists of 8 surface loop coils. To allow imaging of both sides of the neck, the RF array is divided into 2 coil clusters, each with 4 overlapping loop elements. For safety validation, numerical computations of the RF field distribution and the corresponding specific absorption rate were performed on the basis of a heterogeneous human body model. To validate the coil model, maps of the transmit B1+ field were compared between simulation and measurement. In vivo images of a healthy volunteer and a patient (ulcerating plaque and a 50\% stenosis of the right internal carotid artery) were acquired using a 3-dimensional FLASH sequence with a high isotropic spatial resolution of 0.54 mm as well as using pulse-triggered proton density (PD)/T2-weighted turbo spin echo sequences. Results: Measurements of the S-parameters yielded a reflection and isolation of the coil elements of better than -18 and -13 dB, respectively. Measurements of the g-factor indicated good image quality for parallel imaging acceleration factors up to 2.4. A similar distribution and a very good match of the absolute values were found between the measured and simulated B1+ transmit RF field for the validation of the coil model. In vivo images revealed good signal excitation of both sides of the neck and a high vessel-to-background image contrast for the noncontrast-enhanced 3-dimensional FLASH sequence. Imaging at 7 T could depict the extent of stenosis, and revealed the disruption and ulcer of the plaque. Conclusions: This study demonstrates that 2 four-channel transmit/receive RF arrays for each side of the neck is a suitable concept for in vivo MRI of the carotid arteries at 7 Tesla. Further studies are needed to explore and exploit the full potential of 7 T high-field MRI for carotid atherosclerotic plaque imaging.}, language = {en} }