TY - JOUR A1 - Steinbauer, Gerald A1 - Ferrein, Alexander T1 - 20 Years of RoboCup JF - KI - Künstliche Intelligenz Y1 - 2016 U6 - http://dx.doi.org/10.1007/s13218-016-0442-z SN - 1610-1987 VL - 30 IS - 3-4 SP - 221 EP - 224 PB - Springer CY - Berlin ER - TY - JOUR A1 - Ferrein, Alexander A1 - Steinbauer, Gerald T1 - The Interplay of Aldebaran and RoboCup JF - KI - Künstliche Intelligenz Y1 - 2016 U6 - http://dx.doi.org/10.1007/s13218-016-0440-1 SN - 1610-1987 VL - 30 IS - 3-4 SP - 325 EP - 326 PB - Springer CY - Berlin ER - TY - JOUR A1 - Niemueller, Tim A1 - Karras, Ulrich A1 - Ferrein, Alexander T1 - Meisterschaft der Maschinen: Die Industrial Logistic Liga JF - C´t Magazin für Computertechnik Y1 - 2017 IS - 26 ER - TY - JOUR A1 - Werkhausen, Amelie A1 - Albracht, Kirsten A1 - Cronin, Neil J. A1 - Meier, Rahel A1 - Mojsen-Moeller, Jens A1 - Seynnes, Olivier R. T1 - Modulation of muscle-tendon interaction in the human triceps surae during an energy dissipation task JF - Journal of Experimental Biology Y1 - 2017 U6 - http://dx.doi.org/10.1242/jeb.164111 SN - 0022-0949 VL - 220 IS - 22 SP - 4141 EP - 4149 ER - TY - JOUR A1 - Demmer, Julius K. A1 - Chowdhury, Nilanjan Pal A1 - Selmer, Thorsten A1 - Ermler, Ulrich A1 - Buckel, Wolfgang T1 - The semiquinone swing in the bifurcating electron transferring flavoprotein/butyryl-CoA dehydrogenase complex from Clostridium difficile JF - Nature Communications Y1 - 2017 U6 - http://dx.doi.org/10.1038/s41467-017-01746-3 SN - 2041-1723 N1 - Article number 1577 VL - 8 IS - 1 SP - 1 EP - 10 ER - TY - JOUR A1 - Breuer, Lars A1 - Mang, Thomas A1 - Schöning, Michael Josef A1 - Thoelen, Ronald A1 - Wagner, Torsten T1 - Investigation of the spatial resolution of a laser-based stimulation process for light-addressable hydrogels with incorporated graphene oxide by means of IR thermography JF - Sensors and Actuators A: Physical Y1 - 2017 U6 - http://dx.doi.org/10.1016/j.sna.2017.11.031 SN - 0924-4247 VL - 268 SP - 126 EP - 132 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Kotliar, Konstantin A1 - Hauser, Christine A1 - Ortner, Marion A1 - Muggenthaler, Claudia A1 - Diehl-Schmid, Janine A1 - Angermann, Susanne A1 - Hapfelmeier, Alexander A1 - Schmaderer, Christoph A1 - Grimmer, Timo T1 - Altered neurovascular coupling as measured by optical imaging: a biomarker for Alzheimer’s disease JF - Scientific Reports Y1 - 2017 U6 - http://dx.doi.org/10.1038/s41598-017-13349-5 SN - 2045-2322 N1 - Article 12906 VL - 7 IS - 1 SP - 1 EP - 11 PB - Springer Nature CY - Cham ER - TY - JOUR A1 - Ulber, Roland A1 - Tippkötter, Nils T1 - Nitratfreie Molke JF - Rundschau für Fleischhygiene und Lebensmittelüberwachung Y1 - 2009 IS - 4 SP - 150 EP - 152 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 - Tippkötter, Nils A1 - Stückmann, Henning A1 - Kroll, Stephen A1 - Winkelmann, Gunda A1 - Noack, Udo A1 - Scheper, Thomas A1 - Ulber, Roland T1 - A semi-quantitative dipstick assay for microcystin JF - Analytical and Bioanalytical Chemistry N2 - An immunochromatographic lateral flow dipstick assay for the fast detection of microcystin-LR was developed. Colloid gold particles with diameters of 40 nm were used as red-colored antibody labels for the visual detection of the antigen. The new dipstick sensor is capable of detecting down to 5 µg·l−1 (ppb; total inversion of the color signal) or 1 ppb (observation of color grading) of microcystin-LR. The course of the labeling reaction was observed via spectrometric wave shifts caused by the change of particle size during the binding of antibodies. Different stabilizing reagents showed that especially bovine serum albumin (BSA) and casein increase the assays sensitivity and the conjugate stability. Performance of the dipsticks was quantified by pattern processing of capture zone CCD images. Storage stability of dipsticks and conjugate suspensions over 115 days under different conditions were monitored. The ready-to-use dipsticks were successfully tested with microcystin-LR-spiked samples of outdoor drinking- and salt water and applied to the tissue of microcystin-fed mussels. Y1 - 2009 U6 - http://dx.doi.org/10.1007/s00216-009-2750-8 SN - 1618-2650 VL - 394 IS - 3 SP - 863 EP - 869 PB - springer CY - Berlin ER - TY - JOUR A1 - Ulber, R. A1 - Tippkötter, Nils A1 - Buchholz, H. A1 - Demmer, W. A1 - Scheper, T. T1 - Innovative Verfahren in der Molkeaufarbeitung zur Gewinnung neuer Produkte JF - Deutsche Milchwirtschaft Y1 - 2008 SN - 0012-0480 VL - 59 IS - 19 SP - 704 EP - 706 ER - TY - JOUR A1 - Tippkötter, Nils A1 - Roikaew, W. A1 - Ulber, R. T1 - Nitrate removal from whey concentrate with biotechnological regeneration of the waste water JF - European dairy magazine : EDM Y1 - 2008 SN - 0936-6318 IS - 1 SP - 30 EP - 32 ER - TY - JOUR A1 - Tippkötter, Nils A1 - Roikaew, N. A1 - Ulber, R. T1 - Nitratentfernung aus Molkekonzentrat mit biotechnologischer Regeneration der Abwässer JF - Deutsche Milchwirtschaft Y1 - 2007 SN - 0012-0480 VL - 58 IS - 15 SP - 540 EP - 542 ER - TY - JOUR A1 - Balzer, Hermann A1 - Streit, Daniel A1 - Heinze, Marcel ED - Krause, Stefan T1 - Implikationen der Digitalisierung für den Finanzbereich der Unternehmung und das Rollenbild des CFO JF - Betriebswirtschaftliche Implikationen der digitalen Transformation. ZfbF - Schmalenbachs Zeitschrift für betriebswirtschaftliche Forschung, Sonderheft 72 Y1 - 2017 U6 - http://dx.doi.org/10.1007/978-3-658-18751-4_14 N1 - ZfbF - Schmalenbachs Zeitschrift für betriebswirtschaftliche Forschung. Sonderheft 72. Arbeitskreis Finanzierung der Schmalenbach-Gesellschaft e.V. IS - 72 SP - 267 EP - 283 PB - Springer CY - Berlin ER - TY - JOUR A1 - Orzada, Stephan A1 - Bitz, Andreas A1 - Johst, Sören A1 - Gratz, Marcel A1 - Völker, Maximilian N. A1 - Kraff, Oliver A1 - Abuelhaija, Ashraf A1 - Fiedler, Thomas M. A1 - Solbach, Klaus A1 - Quick, Harald H. A1 - Ladd, Mark E. T1 - Analysis of an integrated 8-Channel Tx/Rx body array for use as a body coil in 7-Tesla MRI JF - Frontiers in Physics Y1 - 2017 U6 - http://dx.doi.org/10.3389/fphy.2017.00017 SN - 2296-424X N1 - Article number 17 VL - 5 IS - Jun ER - TY - JOUR A1 - Garibaldi, F. A1 - Beging, Stefan A1 - Canese, R. A1 - Carpinelli, G. A1 - Clinthorne, N. A1 - Colilli, S. A1 - Cosentino, L. A1 - Finocchiaro, P. A1 - Giuliani, F. A1 - Gricia, M. A1 - Lucentini, M. A1 - Majewski, S. A1 - Monno, E. A1 - Musico, P. A1 - Santavenere, F. A1 - Tödter, J. A1 - Wegener, Hans-Peter A1 - Ziemons, Karl T1 - A novel TOF-PET MRI detector for diagnosis and follow up of the prostate cancer JF - European Physical Journal Plus Y1 - 2017 U6 - http://dx.doi.org/10.1140/epjp/i2017-11662-x SN - 2190-5444 VL - 132 IS - 9 PB - Springer CY - Berlin ER - TY - JOUR A1 - Srivastava, A. A1 - Chahar, V. A1 - Sharma, V. A1 - Sun, Y. A1 - Bol, R. A1 - Knolle, F. A1 - Schnug, E. A1 - Hoyler, Friedrich A1 - Naskar, N. A1 - Lahiri, S. A1 - Patnaik, R. T1 - Study of uranium toxicity using low-background gamma-ray spectrometry JF - Journal of Radioanalytical and Nuclear Chemistry Y1 - 2017 U6 - http://dx.doi.org/10.1007/s10967-017-5466-9 SN - 1588-2780 IS - Online first SP - 1 EP - 7 PB - Springer CY - Berlin ER - TY - JOUR A1 - Höttges, Jörg T1 - QKan - Management of drainage system data with QGIS JF - Free and Open Source Software for Geospatial (FOSS4G) Conference Proceedings Y1 - 2017 VL - 17 IS - Article 13 SP - 95 EP - 100 ER - TY - JOUR A1 - Seifarth, Volker A1 - Grosse, Joachim O. A1 - Grossmann, Matthias A1 - Janke, Heinz Peter A1 - Arndt, Patrick A1 - Koch, Sabine A1 - Epple, Matthias A1 - Artmann, Gerhard A1 - Temiz Artmann, Aysegül T1 - Mechanical induction of bi-directional orientation of primary porcine bladder smooth muscle cells in tubular fibrin-poly(vinylidene fluoride) scaffolds for ureteral and urethral repair using cyclic and focal balloon catheter stimulation JF - Journal of Biomaterials Applications Y1 - 2017 U6 - http://dx.doi.org/10.1177/0885328217723178 SN - 1530-8022 VL - 32 IS - 3 SP - 321 EP - 330 PB - Sage CY - London ER - TY - JOUR A1 - Albanna, Walid A1 - Lueke, Jan Niklas A1 - Sjapic, Volha A1 - Kotliar, Konstantin A1 - Hescheler, Jürgen A1 - Clusmann, Hans A1 - Sjapic, Sergej A1 - Alpdogan, Serdan A1 - Schneider, Toni A1 - Schubert, Gerrit Alexander A1 - Neumaier, Felix T1 - Electroretinographic Assessment of Inner Retinal Signaling in the Isolated and Superfused Murine Retina JF - Current Eye Research Y1 - 2017 U6 - http://dx.doi.org/10.1080/02713683.2017.1339807 SN - 1460-2202 IS - Article in press SP - 1 EP - 9 PB - Taylor & Francis CY - London ER - TY - JOUR A1 - Schopp, Christoph A1 - Doll, Timo A1 - Gräser, Ulrich A1 - Harzheim, Thomas A1 - Heuermann, Holger A1 - Kling, Rainer A1 - Marso, Michael T1 - Capacitively Coupled High-Pressure Lamp Using Coaxial Line Networks JF - IEEE Transactions on Microwave Theory and Techniques N2 - This paper describes the development of a capacitively coupled high-pressure lamp with input power between 20 and 43 W at 2.45 GHz, using a coaxial line network. Compared with other electrodeless lamp systems, no cavity has to be used and a reduction in the input power is achieved. Therefore, this lamp is an alternative to the halogen incandescent lamp for domestic lighting. To serve the demands of domestic lighting, the filling of the lamp is optimized over all other resulting requirements, such as high efficacy at low induced powers and fast startups. A workflow to develop RF-driven plasma applications is presented, which makes use of the hot S-parameter technique. Descriptions of the fitting process inside a circuit and FEM simulator are given. Results of the combined ignition and operation network from simulations and measurements are compared. An initial prototype is built and measurements of the lamp's lighting properties are presented along with an investigation of the efficacy optimizations using large signal amplitude modulation. With this lamp, an efficacy of 135 lmW -1 is achieved. Y1 - 2016 U6 - http://dx.doi.org/10.1109/TMTT.2016.2600326 SN - 0018-9480 VL - 64 IS - 10 SP - 3363 EP - 3368 PB - IEEE CY - New York, NY ER - TY - JOUR A1 - Pilas, Johanna A1 - Yazici, Yasemen A1 - Selmer, Thorsten A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Optimization of an amperometric biosensor array for simultaneous measurement of ethanol, formate, d- and l-lactate JF - Electrochimica Acta N2 - The immobilization of NAD+-dependent dehydrogenases, in combination with a diaphorase, enables the facile development of multiparametric sensing devices. In this work, an amperometric biosensor array for simultaneous determination of ethanol, formate, d- and l-lactate is presented. Enzyme immobilization on platinum thin-film electrodes was realized by chemical cross-linking with glutaraldehyde. The optimization of the sensor performance was investigated with regard to enzyme loading, glutaraldehyde concentration, pH, cofactor concentration and temperature. Under optimal working conditions (potassium phosphate buffer with pH 7.5, 2.5 mmol L-1 NAD+, 2.0 mmol L-1 ferricyanide, 25 °C and 0.4% glutaraldehyde) the linear working range and sensitivity of the four sensor elements was improved. Simultaneous and cross-talk free measurements of four different metabolic parameters were performed successfully. The reliable analytical performance of the biosensor array was demonstrated by application in a clarified sample of inoculum sludge. Thereby, a promising approach for on-site monitoring of fermentation processes is provided. KW - Simultaneous determination KW - Enzymatic biosensor KW - Diaphorase KW - Dehydrogenase Y1 - 2017 U6 - http://dx.doi.org/10.1016/j.electacta.2017.07.119 SN - 0013-4686 VL - 251 SP - 256 EP - 262 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Röhlen, Desiree A1 - Pilas, Johanna A1 - Schöning, Michael Josef A1 - Selmer, Thorsten T1 - Development of an amperometric biosensor platform for the combined determination of l-Malic, Fumaric, and l-Aspartic acid JF - Applied Biochemistry and Biotechnology N2 - Three amperometric biosensors have been developed for the detection of L-malic acid, fumaric acid, and L -aspartic acid, all based on the combination of a malate-specific dehydrogenase (MDH, EC 1.1.1.37) and diaphorase (DIA, EC 1.8.1.4). The stepwise expansion of the malate platform with the enzymes fumarate hydratase (FH, EC 4.2.1.2) and aspartate ammonia-lyase (ASPA, EC 4.3.1.1) resulted in multi-enzyme reaction cascades and, thus, augmentation of the substrate spectrum of the sensors. Electrochemical measurements were carried out in presence of the cofactor β-nicotinamide adenine dinucleotide (NAD+) and the redox mediator hexacyanoferrate (III) (HCFIII). The amperometric detection is mediated by oxidation of hexacyanoferrate (II) (HCFII) at an applied potential of + 0.3 V vs. Ag/AgCl. For each biosensor, optimum working conditions were defined by adjustment of cofactor concentrations, buffer pH, and immobilization procedure. Under these improved conditions, amperometric responses were linear up to 3.0 mM for L-malate and fumarate, respectively, with a corresponding sensitivity of 0.7 μA mM−1 (L-malate biosensor) and 0.4 μA mM−1 (fumarate biosensor). The L-aspartate detection system displayed a linear range of 1.0–10.0 mM with a sensitivity of 0.09 μA mM−1. The sensor characteristics suggest that the developed platform provides a promising method for the detection and differentiation of the three substrates. Y1 - 2017 U6 - http://dx.doi.org/10.1007/s12010-017-2578-1 SN - 1559-0291 VL - 183 SP - 566 EP - 581 PB - Springer CY - Berlin ER - TY - JOUR A1 - Honarvarfard, Elham A1 - Gamella, Maria A1 - Poghossian, Arshak A1 - Schöning, Michael Josef A1 - Katz, Evgeny T1 - An enzyme-based reversible Controlled NOT (CNOT) logic gate operating on a semiconductor transducer JF - Applied Materials Today N2 - An enzyme-based biocatalytic system mimicking operation of a logically reversible Controlled NOT (CNOT) gate has been interfaced with semiconductor electronic transducers. Electrolyte–insulator–semiconductor (EIS) structures have been used to transduce chemical changes produced by the enzyme system to an electronically readable capacitive output signal using field-effect features of the EIS device. Two enzymes, urease and esterase, were immobilized on the insulating interface of EIS structure producing local pH changes performing XOR logic operation controlled by various combinations of the input signals represented by urea and ethyl butyrate. Another EIS transducer was functionalized with esterase only, thus performing Identity (ID) logic operation for the ethyl butyrate input. Both semiconductor devices assembled in parallel operated as a logically reversible CNOT gate. The present system, despite its simplicity, demonstrated for the first time logically reversible function of the enzyme system transduced electronically with the semiconductor devices. The biomolecular realization of a CNOT gate interfaced with semiconductors is promising for integration into complex biomolecular networks and future biosensor/biomedical applications. KW - Electrolyte–insulator–semiconductor KW - Capacitive field-effect KW - CNOT KW - XOR KW - Enzyme logic gate Y1 - 2017 U6 - http://dx.doi.org/10.1016/j.apmt.2017.08.003 SN - 2352-9407 VL - 9 SP - 266 EP - 270 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Lambers, Andreas A1 - Bragard, Michael T1 - Kinetische Skulptur - Treffen sich ein E-Techniker und ein Künstler ... JF - Elektor : learn, design, share N2 - Die Verbindung der Welten dressierter Elektronen und grenzenloser Kreativität bietet ein großes Potential; zum Beispiel bei modernen Skulpturen, deren Form sich durch Motoren verändern kann. An der FH Aachen wurde ein solches Projekt verwirklicht: Eine Matrix aus Holzkugeln kann Piktogramme anzeigen, aber auch mathematische Funktionen visualisieren. In diesem Artikel beschreiben wir die clevere Ansteuerung der Motoren. Y1 - 2017 SN - 0932-5468 VL - 48 IS - 9 SP - 78 EP - 83 PB - Elektor-Verlag CY - Aachen ER - TY - JOUR A1 - Tran, Linda A1 - Mottaghy, K. A1 - Arlt-Körfer, Sabine A1 - Waluga, Christian A1 - Behbahani, Mehdi T1 - An experimental study of shear-dependent human platelet adhesion and underlying protein-binding mechanisms in a cylindrical Couette system JF - Biomedizinische Technik Y1 - 2017 U6 - http://dx.doi.org/10.1515/bmt-2015-0034 SN - 0013-5585 VL - 62 IS - 4 SP - 383 EP - 392 PB - De Gruyter CY - Berlin ER - TY - JOUR A1 - Scholl, Fabio A1 - Morais, Paulo A1 - Gabriel, Rayla A1 - Schöning, Michael Josef A1 - Siqueira, Jose Roberto, Jr. A1 - Caseli, Luciano T1 - Carbon nanotubes arranged as smart interfaces in lipid Langmuir-Blodgett films enhancing the enzymatic properties of penicillinase for biosensing applications JF - Applied Materials & Interfaces N2 - In this paper, carbon nanotubes (CNTs) were incorporated in penicillinase-phospholipid Langmuir and Langmuir–Blodgett (LB) films to enhance the enzyme catalytic properties. Adsorption of the penicillinase and CNTs at dimyristoylphosphatidic acid (DMPA) monolayers at the air–water interface was investigated by surface pressure–area isotherms, vibrational spectroscopy, and Brewster angle microscopy. The floating monolayers were transferred to solid supports through the LB technique, forming mixed DMPA-CNTs-PEN films, which were investigated by quartz crystal microbalance, vibrational spectroscopy, and atomic force microscopy. Enzyme activity was studied with UV–vis spectroscopy and the feasibility of the supramolecular device nanostructured as ultrathin films were essayed in a capacitive electrolyte–insulator–semiconductor (EIS) sensor device. The presence of CNTs in the enzyme–lipid LB film not only tuned the catalytic activity of penicillinase but also helped conserve its enzyme activity after weeks, showing increased values of activity. Viability as penicillin sensor was demonstrated with capacitance/voltage and constant capacitance measurements, exhibiting regular and distinctive output signals over all concentrations used in this work. These results may be related not only to the nanostructured system provided by the film, but also to the synergism between the compounds on the active layer, leading to a surface morphology that allowed a fast analyte diffusion because of an adequate molecular accommodation, which also preserved the penicillinase activity. This work therefore demonstrates the feasibility of employing LB films composed of lipids, CNTs, and enzymes as EIS devices for biosensing applications. Y1 - 2017 U6 - http://dx.doi.org/10.1021/acsami.7b08095 SN - 1944-8252 VL - 9 IS - 36 SP - 31054 EP - 31066 PB - ACS CY - Washington ER - TY - JOUR A1 - Werner, Frederik A1 - Miyamoto, Ko-ichiro A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - Lateral resolution enhancement of pulse-driven light-addressable potentiometric sensor JF - Sensor and Actuators B: Chemical N2 - To study chemical and biological processes, spatially resolved determination of the concentrations of one or more analyte species is of distinct interest. With a light-addressable potentiometric sensor (LAPS), chemical images can be created, which visualize the concentration distribution above the sensor plate. One important challenge is to achieve a good lateral resolution in order to detect events that take place in a small and limited region. LAPS utilizes a focused light spot to address the measurement region. By moving this light spot along the semiconductor sensor plate, the concentration distribution can be observed. In this study, we show that utilizing a pulse as light excitation instead of a traditionally used continuously modulated light excitation, the lateral resolution can be improved by a factor of 6 or more. KW - Chemical images KW - LAPS KW - Light-addressable potentiometric sensor Y1 - 2017 U6 - http://dx.doi.org/10.1016/j.snb.2017.02.057 SN - 0925-4005 VL - 248 SP - 961 EP - 965 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Miyamoto, Ko-ichiro A1 - Hayashi, Kosuke A1 - Sakamoto, Azuma A1 - Werner, Frederik A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Yoshinobu, Tatsuo T1 - A high-Q resonance-mode measurement of EIS capacitive sensor by elimination of series resistance JF - Sensor and Actuators B: Chemical N2 - An EIS capacitive sensor is a semiconductor-based potentiometric sensor, which is sensitive to the ion concentration or pH value of the solution in contact with the sensing surface. To detect a small change in the ion concentration or pH, a small capacitance change must be detected. Recently, a resonance-mode measurement was proposed, in which an inductor was connected to the EIS capacitive sensor and the resonant frequency was correlated with the pH value. In this study, the Q factor of the resonant circuit was enhanced by canceling the internal resistance of the reference electrode and the internal resistance of the inductor coil with the help of a bypass capacitor and a negative impedance converter, respectively. 1% variation of the signal in the developed system corresponded to a pH change of 3.93 mpH, which was about 1/12 of the conventional method, suggesting a better performance in detection of a small pH change. KW - Negative impedance convertor KW - Resonance-mode measurement KW - Chemical sensor KW - EIS capacitive sensor Y1 - 2017 U6 - http://dx.doi.org/10.1016/j.snb.2017.03.002 SN - 0925-4005 VL - 248 SP - 1006 EP - 1010 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Arreola, Julio A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Effect of O2 plasma on properties of electrolyte-insulator-semiconductor structures JF - physica status solidi a : applications and materials sciences N2 - Prior to immobilization of biomolecules or cells onto biosensor surfaces, the surface must be physically or chemically activated for further functionalization. Organosilanes are a versatile option as they facilitate the immobilization through their terminal groups and also display self-assembly. Incorporating hydroxyl groups is one of the important methods for primary immobilization. This can be done, for example, with oxygen plasma treatment. However, this treatment can affect the performance of the biosensors and this effect is not quite well understood for surface functionalization. In this work, the effect of O2 plasma treatment on EIS sensors was investigated by means of electrochemical characterizations: capacitance–voltage (C–V) and constant capacitance (ConCap) measurements. After O2 plasma treatment, the potential of the EIS sensor dramatically shifts to a more negative value. This was successfully reset by using an annealing process. KW - surface functionalization KW - O2 plasma KW - hydroxylation KW - electrolyte-insulator semiconductor sensor (EIS) KW - annealing Y1 - 2017 U6 - http://dx.doi.org/10.1002/pssa.201700025 SN - 1862-6319 VL - 214 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Molinnus, Denise A1 - Poghossian, Arshak A1 - Keusgen, Michael A1 - Katz, Evgeny A1 - Schöning, Michael Josef T1 - Coupling of Biomolecular Logic Gates with Electronic Transducers: From Single Enzyme Logic Gates to Sense/Act/Treat Chips JF - Electroanalysis N2 - The integration of biomolecular logic principles with electronic transducers allows designing novel digital biosensors with direct electrical output, logically triggered drug-release, and closed-loop sense/act/treat systems. This opens new opportunities for advanced personalized medicine in the context of theranostics. In the present work, we will discuss selected examples of recent developments in the field of interfacing enzyme logic gates with electrodes and semiconductor field-effect devices. Special attention is given to an enzyme OR/Reset logic gate based on a capacitive field-effect electrolyte-insulator-semiconductor sensor modified with a multi-enzyme membrane. Further examples are a digital adrenaline biosensor based on an AND logic gate with binary YES/NO output and an integrated closed-loop sense/act/treat system comprising an amperometric glucose sensor, a hydrogel actuator, and an insulin (drug) sensor. Y1 - 2017 U6 - http://dx.doi.org/10.1002/elan.201700208 SN - 1521-4109 VL - 29 IS - 8 SP - 1840 EP - 1849 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Jildeh, Zaid B. A1 - Kirchner, Patrick A1 - Oberländer, Jan A1 - Kremers, Alexander A1 - Wagner, Torsten A1 - Wagner, Patrick H. A1 - Schöning, Michael Josef T1 - FEM-based modeling of a calorimetric gas sensor for hydrogen peroxide monitoring JF - physica status solidi a : applications and materials sciences N2 - A physically coupled finite element method (FEM) model is developed to study the response behavior of a calorimetric gas sensor. The modeled sensor serves as a monitoring device of the concentration of gaseous hydrogen peroxide (H2 O2) in a high temperature mixture stream in aseptic sterilization processes. The principle of operation of a calorimetric H2 O2 sensor is analyzed and the results of the numerical model have been validated by using previously published sensor experiments. The deviation in the results between the FEM model and experimental data are presented and discussed. Y1 - 2017 U6 - http://dx.doi.org/10.1002/pssa.201600912 SN - 1862-6319 IS - Early View PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Dantism, Shahriar A1 - Takenaga, Shoko A1 - Wagner, Torsten A1 - Wagner, Patrick A1 - Schöning, Michael Josef T1 - Differential imaging of the metabolism of bacteria and eukaryotic cells based on light-addressable potentiometric sensors JF - Electrochimica Acta N2 - A light-addressable potentiometric sensor (LAPS) is a field-effect-based potentiometric sensor with an electrolyte/insulator/semiconductor (EIS) structure, which is able to monitor analyte concentrations of (bio-)chemical species in aqueous solutions in a spatially resolved way. Therefore, it is also an appropriate tool to record 2D-chemical images of concentration variations on the sensor surface. In the present work, two differential, LAPS-based measurement principles are introduced to determine the metabolic activity of Escherichia coli (E. coli) K12 and Chinese hamster ovary (CHO) cells as test microorganisms. Hereby, we focus on i) the determination of the extracellular acidification rate (ΔpH/min) after adding glucose solutions to the cell suspensions; and ii) recording the amplitude increase of the photocurrent (Iph) related to the produced acids from E. coli K12 bacteria and CHO cells on the sensor surface by 2D-chemical imaging. For this purpose, 3D-printed multi-chamber structures were developed and mounted on the planar sensor-chip surface to define four independent compartments, enabling differential measurements with varying cell concentrations. The differential concept allows eliminating unwanted drift effects and, with the four-chamber structures, measurements on the different cell concentrations were performed simultaneously, thus reducing also the overall measuring time. Y1 - 2017 U6 - http://dx.doi.org/10.1016/j.electacta.2017.05.196 SN - 0013-4686 VL - 246 SP - 234 EP - 241 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Morais, Paulo V. A1 - Gomes, Vanderley F., Jr. A1 - Silva, Anielle C. A. A1 - Dantas, Noelio O. A1 - Schöning, Michael Josef A1 - Siqueira, José R., Jr. T1 - Nanofilm of ZnO nanocrystals/carbon nanotubes as biocompatible layer for enzymatic biosensors in capacitive field-effect devices JF - Journal of Materials Science N2 - The incorporation of nanomaterials that are biocompatible with different types of biological compounds has allowed the development of a new generation of biosensors applied especially in the biomedical field. In particular, the integration of film-based nanomaterials employed in field-effect devices can be interesting to develop biosensors with enhanced properties. In this paper, we studied the fabrication of sensitive nanofilms combining ZnO nanocrystals and carbon nanotubes (CNTs), prepared by means of the layer-by-layer (LbL) technique, in a capacitive electrolyte-insulator-semiconductor (EIS) structure for detecting glucose and urea. The ZnO nanocrystals were incorporated in a polymeric matrix of poly(allylamine) hydrochloride (PAH), and arranged with multi-walled CNTs in a LbL PAH-ZnO/CNTs film architecture onto EIS chips. The electrochemical characterizations were performed by capacitance–voltage and constant capacitance measurements, while the morphology of the films was characterized by atomic force microscopy. The enzymes glucose oxidase and urease were immobilized on film’s surface for detection of glucose and urea, respectively. In order to obtain glucose and urea biosensors with optimized amount of sensitive films, we investigated the ideal number of bilayers for each detection system. The glucose biosensor showed better sensitivity and output signal for an LbL PAH-ZnO/CNTs nanofilm with 10 bilayers. On the other hand, the urea biosensor presented enhanced properties even for the first bilayer, exhibiting high sensitivity and output signal. The presence of the LbL PAH-ZnO/CNTs films led to biosensors with better sensitivity and enhanced response signal, demonstrating that the adequate use of nanostructured films is feasible for proof-of-concept biosensors with improved properties that may be employed for biomedical applications. Y1 - 2017 U6 - http://dx.doi.org/10.1007/s10853-017-1369-y SN - 1573-4803 VL - 52 IS - 20 SP - 12314 EP - 12325 PB - Springer CY - Berlin ER - TY - JOUR A1 - Figueroa-Miranda, Gabriela A1 - Feng, Lingyan A1 - Shiu, Simon Chi-Chin A1 - Dirkzwager, Roderick Marshall A1 - Cheung, Yee-Wai A1 - Tanner, Julian Alexander A1 - Schöning, Michael Josef A1 - Offenhäusser, Andreas A1 - Mayer, Dirk T1 - Aptamer-based electrochemical biosensor for highly sensitive and selective malaria detection with adjustable dynamic response range and reusability JF - Sensor and Actuators B: Chemical N2 - Malaria infection remains a significant risk for much of the population of tropical and subtropical areas, particularly in developing countries. Therefore, it is of high importance to develop sensitive, accurate and inexpensive malaria diagnosis tests. Here, we present a novel aptamer-based electrochemical biosensor (aptasensor) for malaria detection by impedance spectroscopy, through the specific recognition between a highly discriminatory DNA aptamer and its target Plasmodium falciparum lactate dehydrogenase (PfLDH). Interestingly, due to the isoelectric point (pI) of PfLDH, the aptasensor response showed an adjustable detection range based on the different protein net-charge at variable pH environments. The specific aptamer recognition allows sensitive protein detection with an expanded detection range and a low detection limit, as well as a high specificity for PfLDH compared to analogous proteins. The specific feasibility of the aptasensor is further demonstrated by detection of the target PfLDH in human serum. Furthermore, the aptasensor can be easily regenerated and thus applied for multiple usages. The robustness, sensitivity, and reusability of the presented aptasensor make it a promising candidate for point-of-care diagnostic systems. Y1 - 2018 U6 - http://dx.doi.org/10.1016/j.snb.2017.07.117 SN - 0925-4005 VL - 255 IS - P1 SP - 235 EP - 243 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Muschallik, Lukas A1 - Molinnus, Denise A1 - Bongaerts, Johannes A1 - Pohl, Martina A1 - Wagner, Torsten A1 - Schöning, Michael Josef A1 - Siegert, Petra A1 - Selmer, Thorsten T1 - (R,R)-Butane-2,3-diol Dehydrogenase from Bacillus clausii DSM 8716T: Cloning and Expression of the bdhA-Gene, and Initial Characterization of Enzyme JF - Journal of Biotechnology N2 - The gene encoding a putative (R,R)-butane-2,3-diol dehydrogenase (bdhA) from Bacillus clausii DSM 8716T was isolated, sequenced and expressed in Escherichia coli. The amino acid sequence of the encoded protein is only distantly related to previously studied enzymes (identity 33–43%) and exhibited some uncharted peculiarities. An N-terminally StrepII-tagged enzyme variant was purified and initially characterized. The isolated enzyme catalyzed the (R)-specific oxidation of (R,R)- and meso-butane-2,3-diol to (R)- and (S)-acetoin with specific activities of 12 U/mg and 23 U/mg, respectively. Likewise, racemic acetoin was reduced with a specific activity of up to 115 U/mg yielding a mixture of (R,R)- and meso-butane-2,3-diol, while the enzyme reduced butane-2,3-dione (Vmax 74 U/mg) solely to (R,R)-butane-2,3-diol via (R)-acetoin. For these reactions only activity with the co-substrates NADH/NAD+ was observed. The enzyme accepted a selection of vicinal diketones, α-hydroxy ketones and vicinal diols as alternative substrates. Although the physiological function of the enzyme in B. clausii remains elusive, the data presented herein clearly demonstrates that the encoded enzyme is a genuine (R,R)-butane-2,3-diol dehydrogenase with potential for applications in biocatalysis and sensor development. Y1 - 2017 U6 - http://dx.doi.org/10.1016/j.jbiotec.2017.07.020 SN - 0168-1656 VL - 258 SP - 41 EP - 50 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Tippkötter, Nils A1 - Duwe, Anna-Maria A1 - Wiesen, Sebastian A1 - Sieker, Tim A1 - Ulber, Roland T1 - Enzymatic hydrolysis of beech wood lignocellulose at high solid contents and its utilization as substrate for the production of biobutanol and dicarboxylic acids JF - Bioresource Technology N2 - The development of a cost-effective hydrolysis for crude cellulose is an essential part of biorefinery developments. To establish such high solid hydrolysis, a new solid state reactor with static mixing is used. However, concentrations >10% (w/w) cause a rate and yield reduction of enzymatic hydrolysis. By optimizing the synergetic activity of cellulolytic enzymes at solid concentrations of 9%, 17% and 23% (w/w) of crude Organosolv cellulose, glucose concentrations of 57, 113 and 152 g L⁻¹ are reached. However, the glucose yield decreases from 0.81 to 0.72gg⁻¹ at 17% (w/w). Optimal conditions for hydrolysis scale-up under minimal enzyme addition are identified. As result, at 23% (w/w) crude cellulose the glucose yield increases from 0.29 to 0.49gg⁻¹. As proof of its applicability, biobutanol, succinic and itaconic acid are produced with the crude hydrolysate. The potential of the substrate is proven e.g. by a high butanol yield of 0.33gg⁻¹. Y1 - 2014 U6 - http://dx.doi.org/10.1016/j.biortech.2014.06.052 VL - 167 SP - 447 EP - 455 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Wiesen, Sebastian A1 - Tippkötter, Nils A1 - Muffler, Kai A1 - Suck, Kirstin A1 - Sohling, Ulrich A1 - Ruf, Friedrich A1 - Ulber, Roland T1 - Adsorption of fatty acids to layered double hydroxides in aqueous systems JF - Adsorption N2 - Due to their anion exchange characteristics, layered double hydroxides (LDHs) are suitable for the detoxification of aqueous, fatty acid containing fermentation substrates. The aim of this study is to examine the adsorption mechanism, using crude glycerol from plant oil esterification as a model system. Changes in the intercalation structure in relation to the amount of fatty acids adsorbed are monitored by X-ray diffraction and infra-red spectroscopy. Additionally, calcination of LDH is investigated in order to increase the binding capacity for fatty acids. Our data propose that, at ambient temperature, fatty acids can be bound to the hydrotalcite by adsorption or in addition by intercalation, depending on fatty acid concentration. The adsorption of fatty acids from crude glycerol shows a BET-like behavior. Above a fatty acid concentration of 3.5 g L−1, intercalation of fatty acids can be shown by the appearance of an increased interlayer spacing. This observation suggests a two phase adsorption process. Calcination of LDHs allows increasing the binding capacity for fatty acids by more than six times, mainly by reduction of structural CO32−. Y1 - 2015 VL - 21 IS - 6-7 SP - 459 EP - 466 PB - Springer CY - Berlin ER - TY - JOUR A1 - Wulfhorst, Helene A1 - Duwe, Anna-Maria A1 - Merseburg, Johannes A1 - Tippkötter, Nils T1 - Compositional analysis of pretreated (beech) wood using differential scanning calorimetry and multivariate data analysis JF - Tetrahedron N2 - The composition of plant biomass varies depending on the feedstock and pre-treatment conditions and influences its processing in biorefineries. In order to ensure optimal process conditions, the quantitative proportion of the main polymeric components of the pre-treated biomass has to be determined. Current standard procedures for biomass compositional analysis are complex, the measurements are afflicted with errors and therefore often not comparable. Hence, new powerful analytical methods are urgently required to characterize biomass. In this contribution, Differential Scanning Calorimetry (DSC) was applied in combination with multivariate data analysis (MVA) to detect the cellulose content of the plant biomass pretreated by Liquid Hot Water (LHW) and Organosolv processes under various conditions. Unlike conventional techniques, the developed analytic method enables the accurate quantification of monosaccharide content of the plant biomass without any previous sample preparation. It is easy to handle and avoids errors in sample preparation. Y1 - 2016 U6 - http://dx.doi.org/10.1016/j.tet.2016.04.029 VL - 72 IS - 46 SP - 7329 EP - 7334 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Al-Kaidy, Huschyar A1 - Kuthan, Kai A1 - Hering, Thomas A1 - Tippkötter, Nils T1 - Aqueous droplets used as enzymatic microreactors and their electromagnetic actuation JF - Journal of Visualized Experiments N2 - For the successful implementation of microfluidic reaction systems, such as PCR and electrophoresis, the movement of small liquid volumes is essential. In conventional lab-on-a-chip-platforms, solvents and samples are passed through defined microfluidic channels with complex flow control installations. The droplet actuation platform presented here is a promising alternative. With it, it is possible to move a liquid drop (microreactor) on a planar surface of a reaction platform (lab-in-a-drop). The actuation of microreactors on the hydrophobic surface of the platform is based on the use of magnetic forces acting on the outer shell of the liquid drops which is made of a thin layer of superhydrophobic magnetite particles. The hydrophobic surface of the platform is needed to avoid any contact between the liquid core and the surface to allow a smooth movement of the microreactor. On the platform, one or more microreactors with volumes of 10 µL can be positioned and moved simultaneously. The platform itself consists of a 3 x 3 matrix of electrical double coils which accommodate either neodymium or iron cores. The magnetic field gradients are automatically controlled. By variation of the magnetic field gradients, the microreactors' magnetic hydrophobic shell can be manipulated automatically to move the microreactor or open the shell reversibly. Reactions of substrates and corresponding enzymes can be initiated by merging the microreactors or bringing them into contact with surface immobilized catalysts. Y1 - 2016 U6 - http://dx.doi.org/10.3791/54643 SN - 1940-087X IS - Issue 126 ER - TY - JOUR A1 - Sieker, Tim A1 - Ulber, Roland A1 - Dimitrova, Darina A1 - Bart, Hans-Jörg A1 - Neuner, Andreas A1 - Heinzle, Elmar A1 - Tippkötter, Nils T1 - Silage : Fermentationsrohstoff für die chemische Industrie? JF - labor&more N2 - In Anbetracht des zu erwartenden Rückgangs der Verfügbarkeit fossiler Rohstoffe müssen nicht nur für den Energiesektor, sondern auch für die Herstellung industrieller Produkte alternative Rohstoffe gefunden werden. Ein Beispiel für einen nicht in Nahrungsmittelkonkurrenz stehenden nachwachsenden Rohstoff ist grüne Biomasse wie Gras und Klee. Diese lassen sich in Deutschland auf großen Flächen anbauen und enthalten eine Vielzahl potenzieller Substrate für Fermentationen. Y1 - 2009 IS - 2 SP - 44 EP - 45 ER - TY - JOUR A1 - Tippkötter, Nils A1 - Wollny, S. A1 - Kampeis, P. A1 - Oster, J. A1 - Schneider, H. A1 - Ulber, R. T1 - Magnetseparation von Proteinen : Separation von Zielmolekülen durch hochselektive Aptamere JF - GIT Labor-Fachzeitschrift N2 - Durch die Kombination von Oligonukleotid-Liganden (Aptameren) hoher Bindungsaffinitäten mit hochselektiv abtrennbaren magnetisierbaren Mikropartikeln wird eine einstufige Separation von Zielmolekülen aus mikrobiologischen Produktionsansätzen möglich. Die Aptamere werden hierfür reversibel auf den Partikeloberflächen gebunden und für die spezifische Isolierung von Bioprodukten eingesetzt. Die Abtrennung der beladenen Partikel erfolgt durch einen neuen Rotor-Stator-Separator mit Hochgradient-Magnetfeld. Y1 - 2011 VL - 55 IS - 10 SP - 666 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Hebel, Christoph T1 - Erfahrungen mit der RIN und aktuelle Weiterentwicklungen JF - Straßenverkehrstechnik: Organ der Forschungsgesellschaft für Straßen- und Verkehrswesen, der Bundesvereinigung der Straßenbau- und Verkehrsingenieure und der Österreichischen Forschungsgesellschaft Straße und Verkehr; Zeitschrift für Verkehrsplanung, Verkehrsmanagement, Verkehrssicherheit, Verkehrstechnik Y1 - 2017 SN - 0039-2219 N1 - gedruckt in der Bereichsbibliothek Bayernallee vorhanden VL - 61 IS - 7 SP - 443 EP - 448 PB - Kirschbaum-Verlag CY - Bonn ER - TY - JOUR A1 - Kappler-Tanudyaya, Nathalie A1 - Schmitt, Heike A1 - Tippkötter, Nils A1 - Meyer, Lina A1 - Lenzen, Sigurd A1 - Ulber, Roland T1 - Combination of biotransformation and chromatography for the isolation and purification of mannoheptulose JF - Biotechnology Journal N2 - Mannoheptulose is a seven-carbon sugar. It is an inhibitor of glucose-induced insulin secretion due to its ability to selectively inhibit the enzyme glucokinase. An improved procedure for mannoheptulose isolation from avocados is described in this study (based upon the original method by La Forge). The study focuses on the combination of biotransformation and downstream processing (preparative chromatography) as an efficient method to produce a pure extract of mannoheptulose. The experiments were divided into two major phases. In the first phase, several methods and parameters were compared to optimize the mannoheptulose extraction with respect to efficiency and purity. In the second phase, a mass balance of mannoheptulose over the whole extraction process was undertaken to estimate the yield and efficiency of the total extraction process. The combination of biotransformation and preparative chromatography allowed the production of a pure mannoheptulose extract. In a biological test, the sugar inhibited the glucokinase enzyme activity efficiently. Y1 - 2007 U6 - http://dx.doi.org/10.1002/biot.200700004 SN - 1860-7314 VL - 2 IS - 6 SP - 692 EP - 699 ER - TY - JOUR A1 - Tippkötter, Nils A1 - Deterding, A. A1 - Ulber, Roland T1 - Determination of acetic acid in fermentation broth by gas-diffusion technique JF - Engineering in Life Sciences N2 - Due to the interfering effects of acetic acid in many fermentation processes, a gas-diffusion technique was developed for the online determination of acetic acid. The measurements were accomplished with a flow diffusion analysis (FDA) unit from the TRACE Analytics GmbH, Braunschweig, Germany. The diffusion analysis is based on the UV-absorbance of acetic acid at 205 nm. The measurement was achieved by the separation of an acceptor and a carrier stream (acidified fermentation broth) using a gas permeable polytetrafluoroethylene (PTFE) membrane, whereby broth constituents that would otherwise disturb the UV-measurement of acetic acid, are held back efficiently. Merely, the fermentation by-products, e.g. formic acid, is capable of diffusing through the membrane. While formic acid can disturb the measurement, carbon dioxide does not absorb at 205 nm. The method operates with time-dependent sample enrichment. During the analysis, a small volume of the acceptor stream is stopped for a defined time interval in the acceptor chamber. During this period, the gaseous acetic acid diffuses through the membrane and is enriched in the acceptor chamber. Subsequently after the enrichment, the acceptor stream flows through a UV-detector. The intensity of the signal is proportional to the acetic acid concentration. Online measurements in bioreactors via a sterile filtration probe have been accomplished. A linear calibration in the range of 0.5–5.0 g/L acetic acid with a relative standard deviation of <5 % was obtained. A sampling rate of 8 samples per hour was possible. The system was applied for the determination of acetic acid in E. coli fermentation broth. The instrument is easy to clean, very user-friendly and does not require any toxic or expensive reagents. Y1 - 2008 U6 - http://dx.doi.org/10.1002/elsc.200820227 VL - 8 IS - 1, Special Issue: Technical Systems for the Use in Life Sciences SP - 62 EP - 67 ER - TY - JOUR A1 - Graf, Alain-Michel A1 - Steinhof, Rafael A1 - Lotz, Martin A1 - Tippkötter, Nils A1 - Kasper, Cornelia A1 - Beutel, Sascha A1 - Ulber, Roland T1 - Downstream-Processing mit Membranadsorbern zur Isolierung nativer Proteinfraktionen aus Kartoffelfruchtwasser JF - Chemie Ingenieur Technik N2 - Bei der Stärkeproduktion entstehendes Kartoffelfruchtwasser besitzt mit 2 – 3 % einen hohen Anteil an ernährungsphysiologisch interessanten Proteinen. Die industrielle Gewinnung dieser Proteinfracht liefert jedoch lediglich ein minderwertiges, denaturiertes Produkt. Mit Hilfe der Membranadsorber-Technologie lassen sich aus Kartoffelfruchtwasser unter milden Reaktionsbedingungen native bioaktive Proteinfraktionen gewinnen. Geeignete Trennbedingungen wurden im Labormaßstab entwickelt und in den Technikumsmaßstab übertragen. An Anionenaustauscher-Membranadsorbern mit einer Membranfläche von 10 000 cm2 wurde eine Patatinhaltige Fraktion (44 kDa) mit Bindungskapazitäten von 0,37 mg/cm2 isoliert. Eine niedermolekulare Proteinfraktion mit Protease-Inhibitoren konnte durch Kationenaustauscher-Membranadsorber mit Bindungskapazitäten von 1,00 mg/cm2 gewonnen werden. Sie ist für verschiedenste Applikationen in der pharmazeutischen, kosmetischen und der Nahrungsmittelindustrie interessant z. B. für Appetitzügler oder muskelaufbauende Proteinpräparate. Der Aufreinigung der nativen Proteinfraktionen durch Ultra-/Diafiltration schließt sich die Konfektionierung durch Sprühtrocknung an. Die bioanalytische Charakterisierung der Produkte belegt die Reinheit und die enzymatische Aktivität sowie die Abreicherung von Störkomponenten wie Glykoalkaloide und Polyphenoloxidasen. Y1 - 2009 U6 - http://dx.doi.org/10.1002/cite.200800139 VL - 81 IS - 3 SP - 267 EP - 274 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Ulber, Roland A1 - Poth, Sebastian A1 - Monzon, Magaly A1 - Tippkötter, Nils T1 - Prozessintegration von Hydrolyse und Fermentation von Cellulose- Faserstoff JF - Chemie Ingenieur Technik N2 - Ein viel versprechender erneuerbarer Rohstoff für die Produktion von Chemikalien und Treibstoffen ist Lignocellulose aus pflanzlicher Biomasse. Die darin enthaltenen Zucker können mittels enzymatischer Hydrolyse freigesetzt und fermentativ zu Ethanol umgesetzt werden. Ein interessanter Ansatz ist dabei die simultane Verzuckerung und Fermentation. Hefen und Enzyme haben mit 30 °C bzw. 50 °C zwar unterschiedliche Temperaturoptima, es konnte aber gezeigt werden, dass auch bei den niedrigeren Temperaturen eine Umsetzung der Cellulose zu Glucose erfolgt, wenn auch langsamer als bei optimalen Bedingungen. Außerdem konnte in Vorversuchen gezeigt werden, dass Ethanol in den zu erwartenden Konzentrationen keinen Einfluss auf die enzymatische Umsetzung hat. Y1 - 2010 U6 - http://dx.doi.org/10.1002/cite.200900103 SN - 1522-2640 N1 - Special Issue "Biokatalyse" VL - 82 IS - 1-2 SP - 135 EP - 139 ER - TY - JOUR A1 - Sieker, Tim A1 - Neuner, Andreas A1 - Dimitrova, Darina A1 - Tippkötter, Nils A1 - Bart, Hans-Jörg A1 - Heinzle, Elmar A1 - Ulber, Roland T1 - Grassilage als Rohstoff für die chemische Industrie JF - Chemie Ingenieur Technik N2 - Grassilage stellt einen nachwachsenden Rohstoff mit großem Potenzial dar. Neben Cellulose und Hemicellulose enthält sie auch organische Säuren, insbesondere Milchsäure. In einem Bioraffinerie-Projekt wird die Milchsäure aus der Silage isoliert und mit gentechnisch optimierten Stämmen zu L-Lysin weiterverarbeitet. Die Lignocellulose wird hydrolysiert und zu Ethanol fermentiert. Ein besonderes Augenmerk liegt auf der Integration der unterschiedlichen Prozesse sowie der einzelnen Prozessschritte zu einem Gesamtprozess, der sämtliche Inhaltsstoffe der Silage verwertet. Y1 - 2010 U6 - http://dx.doi.org/10.1002/cite.201000088 SN - 1522-2640 VL - 82 IS - 8, Special Issue: Industrielle Nutzung nachwachsender Rohstoffe SP - 1153 EP - 1159 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Tippkötter, Nils A1 - Roikaew, Wipa A1 - Ulber, Roland A1 - Hoffmann, Alexander A1 - Denzler, Hans-Jörg A1 - Buchholz, Heinrich T1 - Paracoccus denitrificans for the effluent recycling during continuous denitrification of liquid food JF - Biotechnology Progress N2 - Nitrate is an undesirable component of several foods. A typical case of contamination with high nitrate contents is whey concentrate, containing nitrate in concentrations up to 25 l. The microbiological removal of nitrate by Paracoccus denitrificans under formation of harmless nitrogen in combination with a cell retention reactor is described here. Focus lies on the resource-conserving design of a microbal denitrification process. Two methods are compared. The application of polyvinyl alcohol-immobilized cells, which can be applied several times in whey feed, is compared with the implementation of a two step denitrification system. First, the whey concentrate's nitrate is removed by ion exchange and subsequently the eluent regenerated by microorganisms under their retention by crossflow filtration. Nitrite and nitrate concentrations were determined by reflectometric color measurement with a commercially available Reflectoquant® device. Correction factors for these media had to be determined. During the pilot development, bioreactors from 4 to 250 mg·L-1 and crossflow units with membrane areas from 0.02 to 0.80 m2 were examined. Based on the results of the pilot plants, a scaling for the exemplary process of denitrifying 1,000 tons per day is discussed. Y1 - 2010 U6 - http://dx.doi.org/10.1002/btpr.384 SN - 8756-7938 VL - 26 IS - 3 SP - 756 EP - 762 PB - Wiley CY - Hoboken, NJ ER - TY - JOUR A1 - Poth, Sebastian A1 - Monzon, Magaly A1 - Tippkötter, Nils A1 - Ulber, Roland T1 - Lignocellulosic biorefinery: Process integration of hydrolysis and fermentation (SSF process) JF - Holzforschung N2 - The aim of the present work is the process integration and the optimization of the enzymatic hydrolysis of wood and the following fermentation of the products to ethanol. The substrate is a fiber fraction obtained by organosolv pre-treatment of beech wood. For the ethanol production, a co-fermentation by two different yeasts (Saccharomyces cerevisiae and Pachysolen tannophilus) was carried out to convert glucose as well as xylose. Two approaches has been followed: 1. A two step process, in which the hydrolysis of the fiber fraction and the fermentation to product are separated from each other. 2. A process, in which the hydrolysis and the fermentation are carried out in one single process step as simultaneous saccharification and fermentation (SSF). Following the first approach, a yield of about 0.15 g ethanol per gram substrate can be reached. Based on the SSF, one process step can be saved, and additionally, the gained yield can be raised up to 0.3 g ethanol per gram substrate. Y1 - 2011 N1 - 11th EWLP, Hamburg, Germany, August 16–19, 2010 VL - 65 IS - 5 SP - 633 EP - 637 PB - De Gruyter CY - Berlin ER - TY - JOUR A1 - Sieker, Tim A1 - Neuner, Andreas A1 - Dimitrova, Darina A1 - Tippkötter, Nils A1 - Muffler, Kai A1 - Bart, Hans-Jörg A1 - Heinzle, Elmar A1 - Ulber, Roland T1 - Ethanol production from grass silage by simultaneous pretreatment, saccharification and fermentation: First steps in the process development JF - Engineering in Life Sciences N2 - Grass silage provides a great potential as renewable feedstock. Two fractions of the grass silage, a press juice and the fiber fraction, were evaluated for their possible use for bioethanol production. Direct production of ethanol from press juice is not possible due to high concentrations of organic acids. For the fiber fraction, alkaline peroxide or enzymatic pretreatment was used, which removes the phenolic acids in the cell wall. In this study, we demonstrate the possibility to integrate the enzymatic pretreatment with a simultaneous saccharification and fermentation to achieve ethanol production from grass silage in a one-process step. Achieved yields were about 53 g ethanol per kg silage with the alkaline peroxide pretreatment and 91 g/kg with the enzymatic pretreatment at concentrations of 8.5 and 14.6 g/L, respectively. Furthermore, it was shown that additional supplementation of the fermentation medium with vitamins, trace elements and nutrient salts is not necessary when the press juice is directly used in the fermentation step. Y1 - 2011 U6 - http://dx.doi.org/10.1002/elsc.201000160 N1 - Special Issue "Bioprocess‐oriented plant design" VL - 11 IS - 4 SP - 436 EP - 442 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Tippkötter, Nils A1 - Al-Kaidy, Huschyar A1 - Wollny, Steffen A1 - Ulber, Roland T1 - Functionalized magnetizable particles for downstream processing in single-use systems JF - Chemie Ingenieur Technik N2 - Biotechnological downstream processing is usually an elaborate procedure, requiring a multitude of unit operations to isolate the target component. Besides the disadvantageous space-time yield, the risks of cross-contaminations and product loss grow fast with the complexity of the isolation procedure. A significant reduction of unit operations can be achieved by application of magnetic particles, especially if these are functionalized with affinity ligands. As magnetic susceptible materials are highly uncommon in biotechnological processes, target binding and selective separation of such particles from fermentation or reactions broths can be done in a single step. Since the magnetizable particles can be produced from iron salts and low priced polymers, a single-use implementation of these systems is highly conceivable. In this article, the principles of magnetizable particles, their synthesis and functionalization are explained. Furthermore, applications in the area of reaction engineering, microfluidics and downstream processing are discussed focusing on established single-use technologies and development potential. Y1 - 2013 U6 - http://dx.doi.org/10.1002/cite.201200130 VL - 85 IS - 1-2: Special Issue: Single-Use Technology SP - 76 EP - 86 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Thiel, Alexander A1 - Tippkötter, Nils A1 - Suck, Kirstin A1 - Sohling, Ulrich A1 - Ruf, Friedrich A1 - Ulber, Roland T1 - New zeolite adsorbents for downstream processing of polyphenols from renewable resources JF - Engineering in Life Sciences N2 - Commercial materials with polyvinylpolypyrrolidone and polymeric amberlites (XAD7HP, XAD16) are commonly used for the adsorptive downstream processing of polyphenols from renewable resources. In this study, beta-zeolite-based adsorbent systems were examined, and their properties were compared to organic resins. Batch adsorption experiments were conducted with synthetic solutions of major polyphenols. Adsorption isotherms and desorption characteristics of individual adsorbent were determined based on these results. Maximum adsorption capacities were calculated using the Langmuir model. For example, the zeolites had capacities up to 203.2 mg/g for ferulic acid. To extend these results to a complex system, additional experiments were performed on rapeseed meal and wheat seed extracts as representative renewable resources. HPLC analysis showed that with 7.5% w/v, which is regarded as the optimum amount of zeolites, zeolites A and B could bind 100% of the major polyphenols as well as release polyphenols at high yields. Additionally, regeneration experiments were performed with isopropyl alcohol at 99°C to evaluate how zeolites regenerate under mild conditions. The results showed only a negligible loss of adsorption capacity and no loss of desorption capacity. In summary, it was concluded that beta-zeolites were promising adsorbents for developing new processes to isolate polyphenols from renewable resources. Y1 - 2013 U6 - http://dx.doi.org/10.1002/elsc.201200188 VL - 13 IS - 3 SP - 239 EP - 246 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Al-Kaidy, Huschyar A1 - Duwe, Anna A1 - Huster, Manuel A1 - Muffler, Kai A1 - Schlegel, Christin A1 - Sieker, Tim A1 - Stadtmüller, Ralf A1 - Tippkötter, Nils A1 - Ulber, Roland T1 - Biotechnologie und Bioverfahrenstechnik – Vom ersten Ullmanns Artikel bis hin zu aktuellen Forschungsthemen JF - Chemie Ingenieur Technik N2 - Biotechnologie und die mit ihr verbundenen technischen Prozesse prägen seit Jahrtausenden die Entwicklung der Menschheit. Ausgehend von empirischen Verfahren, insbesondere zur Herstellung von Lebensmitteln und täglichen Gebrauchsgütern, haben sich diese Disziplinen zu einem der innovativsten Zukunftsfelder entwickelt. Durch das immer detailliertere Verständnis zellulärer Vorgänge können mittlerweile Produktionsstämme gezielt optimiert werden. Im Zusammenspiel mit moderner Prozesstechnik können so eine Vielzahl von Bulk- und Feinchemikalien sowie Pharmazeutika effizient hergestellt werden. In diesem Artikel werden exemplarisch einige der aktuellen Trends vorgestellt. Y1 - 2014 U6 - http://dx.doi.org/10.1002/cite.201400083 SN - 0009-286X VL - 86 IS - 12 SP - 2215 EP - 2225 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Wiesen, Sebastian A1 - Tippkötter, Nils A1 - Muffler, Kai A1 - Suck, Kirstin A1 - Sohling, Ulrich A1 - Ruf, Nils A1 - Ulber, Roland T1 - Adsorptive Vorbehandlung von Rohglycerin für die 1,3-Propandiol Fermentation mit Clostridium diolis JF - Chemie Ingenieur Technik N2 - Bei der Gewinnung von Fettsäuren aus Pflanzenölen, z. B. zur Herstellung von Biopolymeren, oder bei der Biodiesel- und Seifenproduktion, fällt Glycerin als Nebenprodukt an. Bei der Biokonversion dieses Rohstoffes zu 1,3-Propandiol wird der Produktionsorganismus Clostridium diolis durch Verunreinigungen im Rohglycerin gehemmt. Als inhibierende Substanzen konnten freie Fettsäuren identifiziert werden. Mithilfe eines adsorptiven Aufarbeitungsverfahrens ist es gelungen, die Fettsäuren zu entfernen und die Konversionseffizienz zu 1,3-Propandiol zu erhöhen. Y1 - 2014 U6 - http://dx.doi.org/10.1002/cite.201300080 N1 - Englischer Titel: Adsorptive Pretreatment of Crude Glycerol Prior to Fermentation to 1,3-Propanediole by Clostridium Diolis VL - 86 IS - 1-2 SP - 129 EP - 135 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Tippkötter, Nils A1 - Wollny, Steffen A1 - Suck, Kirstin A1 - Sohling, Ulrich A1 - Ruf, Friedrich A1 - Ulber, Roland T1 - Recycling of spent oil bleaching earth as source of glycerol for the anaerobic production of acetone, butanol, and ethanol with Clostridium diolis and lipolytic Clostridium lundense JF - Engineering in Life Sciences N2 - A major part of edible oil is subjected to bleaching procedures, primarily with minerals applied as adsorbers. Their recycling is currently done either by regaining the oil via organic solvent extraction or by using the spent bleaching earth (SBE) as additive for animal feed, etc. As a new method, the reutilization of the by-product SBE for the microbiologic formation of acetone, butanol, and ethanol (ABE) is presented as proof-of-concept. The SBE was taken from a palm oil cleaning process. The recycling concept is based on the application of lipolytic clostridia strains. Due to considerably long fermentation times, co-fermentation with Candida rugosa and enzymatic hydrolyses of the bound oil with a subsequent clostridia fermentation are shown as alternative routes. Anaerobic fermentations under comparison of different clostridia strains were performed with glycerol media, enzymatically hydrolyzed palm oil and SBE. Solutes, side product compositions and productivities were quantified via HPLC. A successful production of ABE solutes from SBE has been done with a yield of 0.15 g butanol per gram of bound glycerol. Thus, the biotechnological recycling of the waste stream is possible in principle. Inhibition of the substrate suspension has been observed. A chromatographic ion-exchange of substrates increased the biomass concentration. Y1 - 2014 U6 - http://dx.doi.org/10.1002/elsc.201300113 SN - 1618-2863 VL - 14 IS - 4 SP - 425 EP - 432 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Pasteur, Aline A1 - Tippkötter, Nils A1 - Kampeis, Percy A1 - Ulber, Roland T1 - Optimization of high gradient magnetic separation filter units for the purification of fermentation products JF - IEEE TRANSACTIONS ON MAGNETICS N2 - High gradient magnetic separation (HGMS) has been established since the early 1970s. A more recent application of these systems is the use in bioprocesses. To integrate the HGMS in a fermentation process, it is necessary to optimize the separation matrix with regard to the magnetic separation characteristics and permeability of the non-magnetizable components of the fermentation broth. As part of the work presented here, a combined fluidic and magnetic force finite element model simulation was created using the software COMSOL Multiphysics and compared with separation experiments. Finally, as optimal lattice orientation of the separation matrix, a transversal rhombohedral arrangement was defined. The high suitability of the new filter matrix has been verified by separation experiments. Y1 - 2014 U6 - http://dx.doi.org/10.1109/TMAG.2014.2325535 SN - 0018-9464 N1 - Article Sequence Number: 5000607 INSPEC Accession Number: 14663042 VL - 50 IS - 10 SP - Artikel 5000607 PB - IEEE CY - New York, NY ER - TY - JOUR A1 - Thiel, Alexander A1 - Muffler, Kai A1 - Tippkötter, Nils A1 - Suck, Kirstin A1 - Sohling, Ulrich A1 - Ruf, Friedrich A1 - Ulber, Roland T1 - Aufarbeitung von Polyphenolen aus Weizen mittels Zeolithen am Beispiel der Ferulasäure JF - Chemie IngenieurTechnik N2 - Aufarbeitung von Polyphenolen aus Weizenmittels Zeolithen am Beispiel der Ferulasa¨ ureAlexander Thiel1, Kai Muffler1, Nils Tippko¨ tter1, Kirstin Suck2, Ulrich Sohling2, Friedrich Ruf3und Roland Ulber1,*DOI: 10.1002/cite.201400031Bei der Ferulasa¨ure handelt es sich um einen Wertstoff, der aus Weizen gewonnen und in der Lebensmittel- und Pharma-industrie eingesetzt werden kann. Der Einsatz von Weizen als nachwachsende Rohstoffquelle ist allerdings nur dann wirt-schaftlich durchfu¨hrbar, wenn eine Prozessintegration in die bestehenden industriellen Verfahren gewa¨hrleistet oder einedirekte Konkurrenz zur Mehl- und Sta¨rkeindustrie vermieden werden kann. In diesem Artikel wird ein Verfahren aufge-zeigt, welches hohe Ausbeuten ermo¨glicht und eine Konkurrenz zu bestehenden Verwertungspfaden vermeidet. Y1 - 2015 U6 - http://dx.doi.org/10.1002/cite.201400031 N1 - Englischer Titel: Downstream Processing of Polyphenols from Wheat by Zeolites using the Example of Ferulic Acid VL - 87 IS - 1-2 SP - 128 EP - 136 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Schumann, Christiane A1 - Rogin, Sabine A1 - Schneider, Horst A1 - Tippkötter, Nils A1 - Oster, Jürgen A1 - Kampeis, Percy T1 - Simultane Atline-Quantifizierung von Magnetpartikeln und Mikroorganismen bei einer HGMS-Filtration JF - Chemie Ingenieur Technik N2 - Es wird eine neue Atline-Messmethode vorgestellt, mit der während einer Hochgradienten-Magnetseparation (HGMS)-Filtration eine simultane Quantifizierung von Magnetpartikeln und Mikroorganismen im Filtrat vorgenommen werden kann. Dabei gelingt die Quantifizierung signifikant besser als mit bisher verwendeten Messmethoden. Mit dieser Methode ist es möglich, die Trennleistung einer HGMS-Filtration zu bestimmen und einen Filterdurchbruch durch Konzentrationsanstiege im Bereich einiger µg L−1 von Magnetpartikeln im Filtrat frühzeitig zu detektieren, ohne dass nennenswerte Partikelmengen verloren gehen. Y1 - 2015 U6 - http://dx.doi.org/10.1002/cite.201300158 N1 - Englischer Titel: Simultaneous Atline Quantification of Magnetic Particles and Microorganisms in the HGMS Filtration VL - 87 IS - 1-2 SP - 137 EP - 149 ER - TY - JOUR A1 - Thiel, Alexander A1 - Muffler, Kai A1 - Tippkötter, Nils A1 - Suck, Kirstin A1 - Sohling, Ulrich A1 - Hruschka, Steffen M. A1 - Ulber, Roland T1 - A novel integrated downstream processing approach to recover sinapic acid, phytic acid and proteins from rapeseed meal JF - Journal of Chemical Technology and Biotechnology N2 - BACKGROUND Currently, several techniques exist for the downstream processing of protein, phytic acid and sinapic acid from rapeseed and rapeseed meal, but no technique has been developed to separate all of the components in one process. In this work, two new downstream processing strategies focusing on recovering sinapic acid, phytic acid and protein from rapeseed meal were established. RESULTS The sinapic acid content was enhanced by a factor of 4.5 with one method and 5.1 with the other. The isolation of sinapic acid was accomplished using a zeolite-based adsorbent with high adsorptive and optimal desorption characteristics. Phytic acid was isolated using the anion-exchange resin Purolite A200®. In addition, the processes resulted in two separated protein fractions. The ratios of globulin and albumin ratio to the total protein were 59.2% and 40.1%, respectively. The steps were then combined in two different ways: (a) a ‘sequential process’ using the zeolite and A200 in batch processes; and (b) a ‘parallel process’ using only A200 in a chromatographic system to separate all of the compounds. CONCLUSIONS It can be concluded that isolation of all three components was possible in both processes. These could enhance the added value of current processes using rapeseed meal as a protein source. © 2015 Society of Chemical Industry Y1 - 2015 U6 - http://dx.doi.org/10.1002/jctb.4664 VL - 90 IS - 11 SP - 1999 EP - 2006 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Al-Kaidy, Huschyar A1 - Duwe, Anna A1 - Huster, Manuel A1 - Muffler, Kai A1 - Schlegel, Christin A1 - Tim, Sieker A1 - Stadtmüller, Ralf A1 - Tippkötter, Nils A1 - Ulber, Roland T1 - Biotechnology and bioprocess engineering – from the first ullmann's article to recent trends JF - ChemBioEng Reviews N2 - For several thousand years, biotechnology and its associated technical processes have had a great impact on the development of mankind. Based on empirical methods, in particular for the production of foodstuffs and daily commodities, these disciplines have become one of the most innovative future issues. Due to the increasing detailed understanding of cellular processes, production strains can now be optimized. In combination with modern bioprocesses, a variety of bulk and fine chemicals as well as pharmaceuticals can be produced efficiently. In this article, some of the current trends in biotechnology are discussed. Y1 - 2015 U6 - http://dx.doi.org/10.1002/cben.201500008 VL - 2 IS - 3 SP - 175 EP - 184 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Al-Kaidy, Huschyar A1 - Tippkötter, Nils T1 - Superparamagnetic hydrophobic particles as shell material for digital microfluidic droplets and proof-of-principle reaction assessments with immobilized laccase JF - Engineering in Life Sciences N2 - In the field of biotechnology and molecular biology, the use of small liquid volumes has significant advantages. In particular, screening and optimization runs with acceptable amounts of expensive and hardly available catalysts, reagents, or biomolecules are feasible with microfluidic technologies. The presented new microfluidic system is based on the inclusion of small liquid volumes by a protective shell of magnetizable microparticles. Hereby, discrete aqueous microreactor drops with volumes of 1–30 μL can be formed on a simple planar surface. A digital movement and manipulation of the microreactor is performed by overlapping magnetic forces. The magnetic forces are generated by an electrical coil matrix positioned below a glass plate. With the new platform technology, several discrete reaction compartments can be moved simultaneously on one surface. Due to the magnetic fields, the reactors can even be merged to initiate reactions by mixing or positioned above surface-immobilized catalysts and then opened by magnetic force. Comparative synthesis routes of the magnetizable shell particles and superhydrophobic glass slides including their performance and stability with the reaction platform are described. The influence of diffusive mass transport during the catalyzed reaction is discussed by evaluation finite element model of the microreactor. Furthermore, a first model dye reaction of the enzyme laccase has been established. Y1 - 2016 U6 - http://dx.doi.org/10.1002/elsc.201400124 VL - 16 IS - 3 SP - 222 EP - 230 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Roth, Jasmine A1 - Tippkötter, Nils T1 - Evaluation of lignocellulosic material for butanol production using enzymatic hydrolysate medium JF - Cellulose Chemistry and Technology N2 - Butanol is a promising gasoline additive and platform chemical that can be readily produced via acetone-butanolethanol (ABE) fermentation from pretreated lignocellulosic materials. This article examines lignocellulosic material from beech wood for ABE fermentation, using Clostridium acetobutylicum. First, the utilization of both C₅₋ (xylose) and C₆₋ (glucose) sugars as sole carbon source was investigated in static cultivation, using serum bottles and synthetic medium. The utilization of pentose sugar resulted in a solvent yield of 0.231 g·g_sugar⁻¹, compared to 0.262 g·g_sugar⁻¹ using hexose. Then, the Organosolv pretreated crude cellulose fibers (CF) were enzymatically decomposed, and the resulting hydrolysate medium was analyzed for inhibiting compounds (furans, organic acids, phenolics) and treated with ionexchangers for detoxification. Batch fermentation in a bioreactor using CF hydrolysate medium resulted in a total solvent yield of 0.20 gABE·g_sugar⁻¹. Y1 - 2016 VL - 50 IS - 3-4 SP - 405 EP - 410 PB - Editura Academiei Romane CY - Bukarest ER - TY - JOUR A1 - Rösch, C. A1 - Kratz, F. A1 - Hering, T. A1 - Trautmann, S. A1 - Umanskaya, N. A1 - Tippkötter, Nils A1 - Müller-Renno, C.M. A1 - Ulber, R. A1 - Hannig, M. A1 - Ziegler, C. T1 - Albumin-lysozyme interactions: cooperative adsorption on titanium and enzymatic activity JF - Colloids and Surfaces B: Biointerfaces N2 - The interplay of albumin (BSA) and lysozyme (LYZ) adsorbed simultaneously on titanium was analyzed by gel electrophoresis and BCA assay. It was found that BSA and lysozyme adsorb cooperatively. Additionally, the isoelectric point of the respective protein influences the adsorption. Also, the enzymatic activity of lysozyme and amylase (AMY) in mixtures with BSA was considered with respect to a possible influence of protein-protein interaction on enzyme activity. Indeed, an increase of lysozyme activity in the presence of BSA could be observed. In contrast, BSA does not influence the activity of amylase. Y1 - 2016 U6 - http://dx.doi.org/10.1016/j.colsurfb.2016.09.048 VL - 149 IS - 1 SP - 115 EP - 121 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Horbach, Andreas A1 - Duong, Minh Tuan A1 - Staat, Manfred T1 - Modelling of compressible and orthotropic surgical mesh implants based on optical deformation measurement JF - Journal of the mechanical behavior of biomedical materials Y1 - 2017 U6 - http://dx.doi.org/10.1016/j.jmbbm.2017.06.012 SN - 1751-6161 VL - 74 SP - 400 EP - 410 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Michael, Hackl A1 - Mayer, Katharina A1 - Weber, Mareike A1 - Staat, Manfred A1 - van Riet, Roger A1 - Burkhart, Klau Josef A1 - Müller, Lars Peter A1 - Wegmann, Kilian T1 - Plate osteosynthesis of proximal ulna fractures : a biomechanical micromotion analysis JF - The journal of hand surgery Y1 - 2017 U6 - http://dx.doi.org/10.1016/j.jhsa.2017.05.014 SN - 0363-5023 VL - 42 IS - 10 SP - 834.e1 EP - 834.e7 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Pfaff, Raphael A1 - Enning, Manfred T1 - Güterwagen 4.0 - Der Güterwagen für das Internet der Dinge. Teil 2: Ausgewählte technische Aspekte und Prozesse JF - ETR - Eisenbahntechnische Rundschau Y1 - 2017 SN - 0013-2845 VL - 66 IS - 5 SP - 74 EP - 77 PB - DVV Media Group CY - Hamburg ER - TY - JOUR A1 - Pfaff, Raphael A1 - Schmidt, Bernd T1 - Daten in der Cloud - und dann? JF - Deine Bahn N2 - Schienenverkehrssysteme stehen in zunehmendem Wettbewerb, sowohl untereinander als auch mit anderen Verkehrsträgern. Als wichtiger Aspekt zur Steigerung der Kosteneffizienz wird die Digitalisierung des Betriebs und der Fahrzeuge betrachtet. Über eine Prognose der Ausfallwahrscheinlichkeit bzw. Restlebensdauer von Subsystemen können mittels Digitalisierung die Instandhaltungskosten gesenkt werden. Die geringen Fehlerraten im System Bahn machen die Nutzung besonderer Simulationstechniken notwendig. In diesem Beitrag wird gezeigt, wie sich die Subsystemverfügbarkeit aus den beobachteten Fehlerraten der Teilfunktionen vorhersagen lässt. Y1 - 2016 SN - 0948-7263 IS - 6 SP - 50 EP - 55 PB - Bahn-Fachverlag CY - Berlin ER - TY - JOUR A1 - Schneider, Wilhelm A1 - Schneider, Bettina A1 - Kinder, Stephanie A1 - Meinhardt, Kerstin T1 - Grundbegriffe der Abgabenordnung JF - Das Wirtschaftsstudium : wisu ; Zeitschrift für Ausbildung, Examen, Berufseinstieg und Fortbildung Y1 - 2017 SN - 0340-3084 N1 - Printausgabe in der Bibliothek Eupener Str. unter der Signatur 43 Z 568 VL - 46 IS - 5 SP - 575 EP - 581 PB - Lange CY - Düsseldorf ER - TY - JOUR A1 - Yoshinobu, Tatsuo A1 - Miyamoto, Ko-ichiro A1 - Werner, Frederik A1 - Poghossian, Arshak A1 - Wagner, Torsten A1 - Schöning, Michael Josef T1 - Light-addressable potentiometric sensors for quantitative spatial imaging of chemical species JF - Annual Review of Analytical Chemistry N2 - A light-addressable potentiometric sensor (LAPS) is a semiconductor-based chemical sensor, in which a measurement site on the sensing surface is defined by illumination. This light addressability can be applied to visualize the spatial distribution of pH or the concentration of a specific chemical species, with potential applications in the fields of chemistry, materials science, biology, and medicine. In this review, the features of this chemical imaging sensor technology are compared with those of other technologies. Instrumentation, principles of operation, and various measurement modes of chemical imaging sensor systems are described. The review discusses and summarizes state-of-the-art technologies, especially with regard to the spatial resolution and measurement speed; for example, a high spatial resolution in a submicron range and a readout speed in the range of several tens of thousands of pixels per second have been achieved with the LAPS. The possibility of combining this technology with microfluidic devices and other potential future developments are discussed. Y1 - 2017 U6 - http://dx.doi.org/10.1146/annurev-anchem-061516-045158 SN - 1936-1327 VL - 10 SP - 225 EP - 246 PB - Annual Reviews CY - Palo Alto, Calif. ER - TY - JOUR A1 - Sousa, Marcos A. M. A1 - Siqueira, Jose R. Jr. A1 - Vercik, Andres A1 - Schöning, Michael Josef A1 - Oliveira, Osvaldo N. Jr. T1 - Determining the optimized layer-by-layer film architecture with dendrimer/carbon nanotubes for field-effect sensors JF - IEEE Sensors Journal N2 - The capacitive electrolyte–insulator–semiconductor (EIS) structure is a typical device based on a field-effect sensor platform. With a simple silicon-based structure, EIS have been useful for several sensing applications, especially with incorporation of nanostructured films to modulate the ionic transport and the flat-band potential. In this paper, we report on ion transport and changes in flat-band potential in EIS sensors made with layer-by-layer films containing poly(amidoamine) (PAMAM) dendrimer and single-walled carbon nanotubes (SWNTs) adsorbed on p-Si/SiO 2 /Ta 2 O 5 chips with an Al ohmic contact. The impedance spectra were fitted using an equivalent circuit model, from which we could determine parameters such as the double-layer capacitance. This capacitance decreased with the number of bilayers owing to space charge accumulated at the electrolyte–insulator interface, up to three PAMAM/SWNTs bilayers, after which it stabilized. The charge-transfer resistance was also minimum for three bilayers, thus indicating that this is the ideal architecture for an optimized EIS performance. The understanding of the influence of nanostructures and the fine control of operation parameters pave the way for optimizing the design and performance of new EIS sensors. Y1 - 2017 U6 - http://dx.doi.org/10.1109/JSEN.2017.2653238 SN - 1558-1748 VL - 17 IS - 6 SP - 1735 EP - 1740 PB - IEEE CY - New York ER - TY - JOUR A1 - Gamella, Maria A1 - Zakharchenko, Andrey A1 - Guz, Nataliia A1 - Masi, Madeline A1 - Minko, Sergiy A1 - Kolpashchikov, Dmitry M. A1 - Iken, Heiko A1 - Poghossian, Arshak A1 - Schöning, Michael Josef A1 - Katz, Evgeny T1 - DNA computing system activated by electrochemically triggered DNA realease from a polymer-brush-modified electrode array JF - Electroanalysis N2 - An array of four independently wired indium tin oxide (ITO) electrodes was used for electrochemically stimulated DNA release and activation of DNA-based Identity, AND and XOR logic gates. Single-stranded DNA molecules were loaded on the mixed poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA)/poly(methacrylic acid) (PMAA) brush covalently attached to the ITO electrodes. The DNA deposition was performed at pH 5.0 when the polymer brush is positively charged due to protonation of tertiary amino groups in PDMAEMA, thus resulting in electrostatic attraction of the negatively charged DNA. By applying electrolysis at −1.0 V(vs. Ag/AgCl reference) electrochemical oxygen reduction resulted in the consumption of hydrogen ions and local pH increase near the electrode surface. The process resulted in recharging the polymer brush to the negative state due to dissociation of carboxylic groups of PMAA, thus repulsing the negatively charged DNA and releasing it from the electrode surface. The DNA release was performed in various combinations from different electrodes in the array assembly. The released DNA operated as input signals for activation of the Boolean logic gates. The developed system represents a step forward in DNA computing, combining for the first time DNA chemical processes with electronic input signals. Y1 - 2017 U6 - http://dx.doi.org/10.1002/elan.201600389 SN - 1521-4109 VL - 29 IS - 2 SP - 398 EP - 408 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Bronder, Thomas A1 - Poghossian, Arshak A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Label-free detection of double-stranded DNA molecules with polyelectrolyte-modified capacitive field-effect sensors T1 - Markierungsfreie Detektion doppelsträngiger DNA Moleküle mit Hilfe von Polyelektrolyt-modifizierten kapazitiven Feldeffekt-Sensoren JF - tm - Technisches Messen N2 - 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. Y1 - 2017 U6 - http://dx.doi.org/10.1515/teme-2017-0015 VL - 84 IS - 10 SP - 628 EP - 634 PB - De Gruyter CY - Oldenbourg ER - TY - JOUR A1 - Arreola, Julio A1 - Oberländer, Jan A1 - Mätzkow, M. A1 - Keusgen, Michael A1 - Schöning, Michael Josef T1 - Surface functionalization for spore-based biosensors with organosilanes JF - Electrochimica Acta N2 - 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. Y1 - 2017 U6 - http://dx.doi.org/10.1016/j.electacta.2017.04.157 SN - 0013-4686 VL - 241 SP - 237 EP - 243 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Balzer, Hermann A1 - Streit, Daniel T1 - Das Translationsrisiko multinationaler Konzerne in Deutschland: Eine explorative Analyse von Verständnis, Bedeutung und Management-Praxis mit Hilfe der Critical Incident Technique JF - Schmalenbachs Zeitschrift für betriebswirtschaftliche Forschung Y1 - 2017 U6 - http://dx.doi.org/10.1007/s41471-017-0029-x SN - 2366-6153 N1 - Arbeitskreis Finanzierung der Schmalenbach-Gesellschaft e.V. IS - Online first SP - 1 EP - 40 PB - Springer CY - Berlin ER - TY - JOUR A1 - Hansen, Volkert W. A1 - Bitz, Andreas A1 - Streckert, Joachim R. T1 - RF Exposure of Biological Systems in Radial Waveguides JF - IEEE Transactions on Electromagnetic Compatibility Y1 - 1999 U6 - http://dx.doi.org/10.1109/15.809852 SN - 1558-187X VL - 41 IS - 4 SP - 487 EP - 493 ER - TY - JOUR A1 - Sommer, Angela M. A1 - Streckert, Joachim A1 - Bitz, Andreas A1 - Hansen, Volkert W. A1 - Lerchl, Alexander T1 - No effects of GSM-modulated 900 MHz electromagnetic fields on survival rate and spontaneous development of lymphoma in female AKR/J mice JF - BMC Cancer Y1 - 2004 U6 - http://dx.doi.org/10.1186/1471-2407-4-77 VL - 77 IS - 4 ER - TY - JOUR A1 - Ndoumbè Mbonjo Mbonjo, H. A1 - Streckert, J. A1 - Bitz, Andreas A1 - Hansen, V. A1 - Glasmachers, A. A1 - Gencol, S. A1 - Rozic, D. T1 - Generic UMTS test signal for RF bioelectromagnetic studies JF - Bioelectromagnetics Y1 - 2004 U6 - http://dx.doi.org/10.1002/bem.20007 SN - 1521-186X VL - 25 IS - 6 SP - 415 EP - 425 ER - TY - JOUR A1 - Wissen, M. A1 - Bogdanski, N. A1 - Scheer, H.-C. A1 - Bitz, Andreas A1 - Ahrens, G. A1 - Gruetzner, G. T1 - Implication of the light polarisation for UV curing of pre-patterned resists JF - Microelectronic Engineering Y1 - 2005 U6 - http://dx.doi.org/10.1016/j.mee.2004.12.099 SN - 0167-9317 VL - 78-79 SP - 659 EP - 664 ER - TY - JOUR A1 - Franke, Helmut A1 - Streckert, Joachim A1 - Bitz, Andreas A1 - Goeke, Johannes A1 - Hansen, Volkert A1 - Ringelstein, E. Bernd A1 - Nattkämper, Heiner A1 - Galle, Hans-Joachim A1 - Stögbauer, Florian T1 - Effects of Universal Mobile Telecommunications System (UMTS) electromagnetic fields on the blood-brain barrier in vitro JF - Radiation Research Y1 - 2005 U6 - http://dx.doi.org/10.1667/RR3424.1 SN - 1938-5404 VL - 164 IS - 3 SP - 258 EP - 269 ER - TY - JOUR A1 - Sukhotina, Irina A1 - Streckert, Joachim R. A1 - Bitz, Andreas A1 - Hansen, Volkert W. A1 - Lerchl, Alexander T1 - 1800 MHz electromagnetic field effects on melatonin release from isolated pineal glands JF - Journal of Pineal Research Y1 - 2006 U6 - http://dx.doi.org/10.1111/j.1600-079X.2005.00284.x SN - 1600-079X VL - 40 IS - 1 SP - 86 EP - 91 ER - TY - JOUR A1 - Sommer, Angela M. A1 - Bitz, Andreas A1 - Streckert, Joachim A1 - Hansen, Volkert W. A1 - Lerchl, Alexander T1 - Lymphoma development in mice chronically exposed to UMTS-modulated radiofrequency electromagnetic fields JF - Radiation Research Y1 - 2007 U6 - http://dx.doi.org/10.1667/RR0857.1 SN - 1938-5404 VL - 168 IS - 1 SP - 72 EP - 80 ER - TY - JOUR A1 - Reinhardt, T. A1 - Bitz, Andreas A1 - El Ouardi, A. A1 - Streckert, J. A1 - Sommer, A. A1 - Lerchl, A. A1 - Hansen, V. T1 - Exposure set-ups for in vivo experiments using radial waveguides JF - Radiation Protection Dosimetry Y1 - 2007 U6 - http://dx.doi.org/10.1093/rpd/ncm370 SN - 1742-3406 VL - 124 IS - 1 SP - 21 EP - 26 ER - TY - JOUR A1 - Lerchl, Alexander A1 - Krüger, Heike A1 - Niehaus, Michael A1 - Streckert, Joachim R. A1 - Bitz, Andreas A1 - Hansen, Volkert T1 - Effects of mobile phone electromagnetic fields at nonthermal SAR values on melatonin and body weight of Djungarian hamsters (Phodopus sungorus) JF - Journal of Pineal Research Y1 - 2008 U6 - http://dx.doi.org/10.1111/j.1600-079X.2007.00522.x SN - 1600-079X VL - 44 IS - 3 SP - 267 EP - 272 ER - TY - JOUR A1 - Klomp, D. W. J. A1 - Bitz, Andreas A1 - Heerschap, A. A1 - Scheenen, T. W. J. T1 - Proton spectroscopic imaging of the human prostate at 7 T JF - NMR in Biomedicine Y1 - 2009 U6 - http://dx.doi.org/10.1002/nbm.1360 SN - 1099-1492 VL - 22 IS - 5 SP - 495 EP - 501 ER - TY - JOUR A1 - Schlamann, M. A1 - Yoon, M.-S. A1 - Maderwald, S. A1 - Pietrzyk, T. A1 - Bitz, Andreas A1 - Gerwig, M. A1 - Forsting, M. A1 - Ladd, S. C. A1 - Ladd, M. E. A1 - Kastrup, O. T1 - Auswirkungen der Magnetresonanztomografie auf die Elektrophysiologie des motorischen Kortex: eine Studie mit transkranieller Magnetstimulation T1 - Effects of MRI on the electrophysiology of the motor cortex: a TMS study JF - RöFo - Fortschritte auf dem Giebiet der Röntgenstrahlen und der bildgebenden Verfahren Y1 - 2009 U6 - http://dx.doi.org/10.1055/s-0028-1109038 SN - 1438-9029 VL - 181 IS - 3 SP - 215 EP - 219 PB - Thieme CY - Stuttgart ER - TY - JOUR A1 - Kraff, Oliver A1 - Bitz, Andreas A1 - Kruszona, Stefan A1 - Orzada, Stephan A1 - Schaefer, Lena C. A1 - Theysohn, Jens M. A1 - Maderwald, Stefan A1 - Ladd, Mark E. A1 - Quick, Harald H. T1 - An eight-channel phased array RF coil for spine MR imaging at 7 T JF - Investigative Radiology Y1 - 2009 U6 - http://dx.doi.org/10.1097/RLI.0b013e3181b24ab7 SN - 1536-0210 VL - 44 IS - 11 SP - 734 EP - 740 PB - Lippincott Williams & Wilkins ER - TY - JOUR A1 - Schlamann, Marc A1 - Yoon, Min-Suk A1 - Maderwald, Stefan A1 - Pietrzyk, Thomas A1 - Bitz, Andreas A1 - Gerwig, Marcus A1 - Forsting, Michael A1 - Ladd, Susanne C. A1 - Ladd, Mark E. A1 - Kastrup, Oliver T1 - Short term effects of magnetic resonance imaging on excitability of the motor cortex at 1.5T and 7T JF - Academic Radiology N2 - 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. Y1 - 2010 U6 - http://dx.doi.org/10.1016/j.acra.2009.10.004 SN - 1076-6332 VL - 17 IS - 3 SP - 277 EP - 281 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Bitz, Andreas A1 - Zhou, Yi A1 - El Quardi, Abdessamad A1 - Streckert, Joachim T1 - Occupational Exposure at Mobile Communication Base Station Antenna Sites JF - Frequenz Y1 - 2009 U6 - http://dx.doi.org/10.1515/FREQ.2009.63.7-8.123 SN - 2191-6349 VL - 63 IS - 7-8 SP - 123 EP - 128 ER - TY - JOUR A1 - Schlamann, Marc A1 - Voigt, Melanie A. A1 - Maderwald, Stefan A1 - Bitz, Andreas A1 - Kraff, Oliver A1 - Ladd, Susanne C. A1 - Ladd, Mark E. A1 - Forsting, Michael A1 - Wilhelm, Hans T1 - Exposure to high-field MRI does not affect cognitive function JF - Journal of Magnetic Resonance Imaging N2 - 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. Y1 - 2010 U6 - http://dx.doi.org/10.1002/jmri.22065 SN - 1522-2586 VL - 31 IS - 5 SP - 1061 EP - 1066 PB - Wiley-Liss CY - New York ER - TY - JOUR A1 - El Quardi, A. A1 - Streckert, J. A1 - Bitz, Andreas A1 - Münkner, S. A1 - Engel, J. A1 - Hansen, V. T1 - New fin-line devices for radiofrequency exposure of small biological samples in vitro allowing whole-cell patch clamp recordings JF - Bioelectromagnetics N2 - 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. Y1 - 2011 U6 - http://dx.doi.org/10.1002/bem.20621 SN - 1521-186X VL - 32 IS - 2 SP - 102 EP - 112 PB - Wiley CY - Weinheim ER - TY - JOUR A1 - Kraff, Oliver A1 - Bitz, Andreas A1 - Breyer, Tobias A1 - Kruszona, Stefan A1 - Maderwald, Stefan A1 - Brote, Irina A1 - Gizewski, Elke R. A1 - Ladd, Mark E. A1 - Quick, Harald H. T1 - A transmit/receive radiofrequency array for imaging the carotid arteries at 7 Tesla: coil design and first in vivo results JF - Investigative Radiology N2 - 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. Y1 - 2011 U6 - http://dx.doi.org/10.1097/RLI.0b013e318206cee4 SN - 1536-0210 VL - 46 IS - 4 SP - 246 EP - 254 PB - Wolters Kluwer CY - Köln ER - TY - JOUR A1 - Ciritsis, Alexander A1 - Horbach, Andreas A1 - Staat, Manfred A1 - Kuhl, Christiane K. A1 - Kraemer, Nils Andreas T1 - Porosity and tissue integration of elastic mesh implants evaluated in vitro and in vivo JF - Journal of Biomedical Materials Research: Part B: Applied Biomaterials N2 - Purpose In vivo, a loss of mesh porosity triggers scar tissue formation and restricts functionality. The purpose of this study was to evaluate the properties and configuration changes as mesh deformation and mesh shrinkage of a soft mesh implant compared with a conventional stiff mesh implant in vitro and in a porcine model. Material and Methods Tensile tests and digital image correlation were used to determine the textile porosity for both mesh types in vitro. A group of three pigs each were treated with magnetic resonance imaging (MRI) visible conventional stiff polyvinylidene fluoride meshes (PVDF) or with soft thermoplastic polyurethane meshes (TPU) (FEG Textiltechnik mbH, Aachen, Germany), respectively. MRI was performed with a pneumoperitoneum at a pressure of 0 and 15 mmHg, which resulted in bulging of the abdomen. The mesh-induced signal voids were semiautomatically segmented and the mesh areas were determined. With the deformations assessed in both mesh types at both pressure conditions, the porosity change of the meshes after 8 weeks of ingrowth was calculated as an indicator of preserved elastic properties. The explanted specimens were examined histologically for the maturity of the scar (collagen I/III ratio). Results In TPU, the in vitro porosity increased constantly, in PVDF, a loss of porosity was observed under mild stresses. In vivo, the mean mesh areas of TPU were 206.8 cm2 (± 5.7 cm2) at 0 mmHg pneumoperitoneum and 274.6 cm2 (± 5.2 cm2) at 15 mmHg; for PVDF the mean areas were 205.5 cm2 (± 8.8 cm2) and 221.5 cm2 (± 11.8 cm2), respectively. The pneumoperitoneum-induced pressure increase resulted in a calculated porosity increase of 8.4% for TPU and of 1.2% for PVDF. The mean collagen I/III ratio was 8.7 (± 0.5) for TPU and 4.7 (± 0.7) for PVDF. Conclusion The elastic properties of TPU mesh implants result in improved tissue integration compared to conventional PVDF meshes, and they adapt more efficiently to the abdominal wall. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 827–833, 2018. Y1 - 2018 U6 - http://dx.doi.org/10.1002/jbm.b.33877 SN - 1552-4981 VL - 106 IS - 2 SP - 827 EP - 833 PB - Wiley CY - New York, NY ER - TY - JOUR A1 - Kraff, Oliver A1 - Bitz, Andreas A1 - Dammann, Philipp A1 - Ladd, Susanne C. A1 - Ladd, Mark E. A1 - Quick, Harald H. T1 - An eight-channel transmit/receive multipurpose coil for musculoskeletal MR imaging at 7 T JF - Medical Physics N2 - Purpose: MRI plays a leading diagnostic role in assessing the musculoskeletal (MSK) system and is well established for most questions at clinically used field strengths (up to 3 T). However, there are still limitations in imaging early stages of cartilage degeneration, very fine tendons and ligaments, or in locating nerve lesions, for example. 7 T MRI of the knee has already received increasing attention in the current published literature, but there is a strong need to develop new radiofrequency (RF) coils to assess more regions of the MSK system. In this work, an eight-channel transmit/receive RF array was built as a multipurpose coil for imaging some of the thus far neglected regions. An extensive coil characterization protocol and first in vivo results of the human wrist, shoulder, elbow, knee, and ankle imaged at 7 T will be presented. Methods: Eight surface loop coils with a dimension ofurn:x-wiley:00942405:media:mp7176:mp7176-math-0001 were machined from FR4 circuit board material. To facilitate easy positioning, two coil clusters, each with four loop elements, were combined to one RF transmit/receive array. An overlapped and shifted arrangement of the coil elements was chosen to reduce the mutual inductance between neighboring coils. A phantom made of body-simulating liquid was used for tuning and matching on the bench. Afterward, the S-parameters were verified on a human wrist, elbow, and shoulder. For safety validation, a detailed compliance test was performed including full wave simulations of the RF field distribution and the corresponding specific absorption rate (SAR) for all joints. In vivo images of four volunteers were assessed with gradient echo and spin echo sequences modified to obtain optimal image contrast, full anatomic coverage, and the highest spatial resolution within a reasonable acquisition time. The performance of the RF coil was additionally evaluated by in vivo B1 mapping. Results: A comparison of B1 per unit power, flip angle distribution, and anatomic images showed a fairly homogeneous excitation for the smaller joints (elbow, wrist, and ankle), while for the larger joints, the shoulder and especially the knee, B1 inhomogeneities and limited penetration depth were more pronounced. However, the greater part of the shoulder joint could be imaged.In vivo images rendered very fine anatomic details such as fascicles of the median nerve and the branching of the nerve bundles. High-resolution images of cartilage, labrum, and tendons could be acquired. Additionally, turbo spin echo (TSE) and inversion recovery sequences performed very well. Conclusions: This study demonstrates that the concept of two four-channel transmit/receive RF arrays can be used as a multipurpose coil for high-resolutionin vivo MR imaging of the musculoskeletal system at 7 T. Not only gradient echo but also typical clinical and SAR-intensive sequences such as STIR and TSE performed well. Imaging of small structures and peripheral nerves could in particular benefit from this technique. Y1 - 2010 U6 - http://dx.doi.org/10.1118/1.3517176 SN - 2473-4209 VL - 37 IS - 12 SP - 6368 EP - 6376 PB - Wiley CY - Hoboken, NJ ER - TY - JOUR A1 - Orzada, Stephan A1 - Bitz, Andreas A1 - Schäfer, Lena C. A1 - Ladd, Susanne C. A1 - Ladd, Mark E. A1 - Maderwald, Stefan T1 - Open design eight-channel transmit/receive coil for high-resolution and real-time ankle imaging at 7 T JF - Medical Physics N2 - Purpose: At 1.5 T, real-time MRI of joint movement has been shown to be feasible. However, 7 T, provides higher SNR and thus an improved potential for parallel imaging acceleration. The purpose of this work was to build an open, U-shaped eight-channel transmit/receive microstrip coil for 7 T MRI to enable high-resolution and real-time imaging of the moving ankle joint. Methods: A U-shaped eight-channel transmit/receive array for the human ankle was built.urn:x-wiley:00942405:mp3399:equation:mp3399-math-0001-parameters and urn:x-wiley:00942405:mp3399:equation:mp3399-math-0002-factor were measured. SAR calculations of different ankle postures were performed to ensure patient safety. Inhomogeneities in the transmit field consequent to the open design were compensated for by the use of static RF shimming. High-resolution and real-time imaging was performed in human volunteers. Results: The presented array showed good performance with regard to patient comfort and image quality. High acceleration factors of up to 4 are feasible without visible acceleration artifacts. Reasonable image homogeneity was achieved with RF shimming. Conclusions: Open, noncylindrical designs for transmit/receive coils are practical at 7 T and real-time imaging of the moving joint is feasible with the presented coil design. Y1 - 2011 U6 - http://dx.doi.org/10.1118/1.3553399 SN - 2473-4209 VL - 38 IS - 3 SP - 1162 EP - 1167 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Prochnow, Nora A1 - Gebing, Tina A1 - Ladage, Kerstin A1 - Krause-Finkeldey, Dorothee A1 - Ourdi, Abessamad El A1 - Bitz, Andreas A1 - Streckert, Joachim A1 - Hansen, Volkert A1 - Dermietzel, Rolf T1 - Electromagnetic field effect or simply stress? Effects of UMTS exposure on hippocampal longterm plasticity in the context of procedure related hormone release JF - PLoS one N2 - Harmful effects of electromagnetic fields (EMF) on cognitive and behavioural features of humans and rodents have been controversially discussed and raised persistent concern about adverse effects of EMF on general brain functions. In the present study we applied radio-frequency (RF) signals of the Universal Mobile Telecommunications System (UMTS) to full brain exposed male Wistar rats in order to elaborate putative influences on stress hormone release (corticosteron; CORT and adrenocorticotropic hormone; ACTH) and on hippocampal derived synaptic long-term plasticity (LTP) and depression (LTD) as electrophysiological hallmarks for memory storage and memory consolidation. Exposure was computer controlled providing blind conditions. Nominal brain-averaged specific absorption rates (SAR) as a measure of applied mass-related dissipated RF power were 0, 2, and 10 W/kg over a period of 120 min. Comparison of cage exposed animals revealed, regardless of EMF exposure, significantly increased CORT and ACTH levels which corresponded with generally decreased field potential slopes and amplitudes in hippocampal LTP and LTD. Animals following SAR exposure of 2 W/kg (averaged over the whole brain of 2.3 g tissue mass) did not differ from the sham-exposed group in LTP and LTD experiments. In contrast, a significant reduction in LTP and LTD was observed at the high power rate of SAR (10 W/kg). The results demonstrate that a rate of 2 W/kg displays no adverse impact on LTP and LTD, while 10 W/kg leads to significant effects on the electrophysiological parameters, which can be clearly distinguished from the stress derived background. Our findings suggest that UMTS exposure with SAR in the range of 2 W/kg is not harmful to critical markers for memory storage and memory consolidation, however, an influence of UMTS at high energy absorption rates (10 W/kg) cannot be excluded. Y1 - 2011 U6 - http://dx.doi.org/10.1371/journal.pone.0019437 VL - 6 IS - 5 PB - PLOS CY - San Francisco ER - TY - JOUR A1 - Yazdanbakhsh, Pedram A1 - Solbach, Klaus A1 - Bitz, Andreas T1 - Variable power combiner for RF mode shimming in 7-T MR imaging JF - IEEE Transaction on Biomedical Engineering N2 - This contribution discusses the utilization of RF power in an MRI system with RF mode shimming which enables the superposition of circularly polarized modes of a transmit RF coil array driven by a Butler matrix. Since the required power for the individual modes can vary widely, mode-shimming can result in a significant underutilization of the total available RF power. A variable power combiner (VPC) is proposed to improve the power utilization: it can be realized as a reconfiguration of the MRI transmit system by the inclusion of one additional matrix network which receives the power from all transmit amplifiers at its input ports and provides any desired (combined) power distribution at its output ports by controlling the phase and amplitude of the amplifiers’ input signals. The power distribution at the output ports of the VPC is then fed into the “mode” ports of the coil array Butler matrix in order to superimpose the spatial modes at the highest achievable power utilization. The VPC configuration is compared to the standard configuration of the transmit chain of our MRI system with 8 transmit channels and 16 coils. In realistic scenarios, improved power utilization was achieved from 17% to 60% and from 14% to 55% for an elliptical phantom and a region of interest in the abdomen, respectively, and an increase of the power utilization of 1 dB for a region of interest in the upper leg. In general, it is found that the VPC allows significant improvement in power utilization when the shimming solution demands only a few modes to be energized, while the technique can yield loss in power utilization in cases with many modes required at high power level. Y1 - 2012 U6 - http://dx.doi.org/10.1109/TBME.2012.2205926 SN - 1558-2531 VL - 59 IS - 9 SP - 2549 EP - 2557 PB - IEEE CY - New York ER - TY - JOUR A1 - Umutlu, Lale A1 - Bitz, Andreas A1 - Maderwald, Stefan A1 - Orzada, Stephan A1 - Kinner, Sonja A1 - Kraff, Oliver A1 - Brote, Irina A1 - Ladd, Susanne C. A1 - Schroeder, Tobias A1 - Forsting, Michael T1 - Contrast-enhanced ultra-high-field liver MRI: a feasibility trial JF - European Journal of Radiology Y1 - 2013 U6 - http://dx.doi.org/10.1016/j.ejrad.2011.07.004 SN - 0720-048X VL - 82 IS - 5 SP - 760 EP - 767 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Finger, Felix T1 - Senkrechtstarter: FH-Absolvent wird für Transportdrohne ausgezeichnet JF - campushunter: das etwas andere Karrieremagazin - Wintersemester 16/17 Y1 - 2016 SN - 2196-9426 IS - 17. Regionalausgabe Aachen SP - 116 EP - 117 PB - Campushunter Media CY - Heidelberg ER - TY - JOUR A1 - Orzada, Stephan A1 - Maderwald, Stefan A1 - Poser, Benedikt Andreas A1 - Bitz, Andreas A1 - Quick, Harald H. A1 - Ladd, Mark E. T1 - RF excitation using time interleaved acquisition of modes (TIAMO) to address B1 inhomogeneity in high-field MRI JF - Magnetic Resonance in Medicine N2 - As the field strength and, therefore, the operational frequency in MRI is increased, the wavelength approaches the size of the human head/body, resulting in wave effects, which cause signal decreases and dropouts. Several multichannel approaches have been proposed to try to tackle these problems, including RF shimming, where each element in an array is driven by its own amplifier and modulated with a certain (constant) amplitude and phase relative to the other elements, and Transmit SENSE, where spatially tailored RF pulses are used. In this article, a relatively inexpensive and easy to use imaging scheme for 7 Tesla imaging is proposed to mitigate signal voids due to B1 field inhomogeneity. Two time-interleaved images are acquired using a different excitation mode for each. By forming virtual receive elements, both images are reconstructed together using GRAPPA to achieve a more homogeneous image, with only small SNR and SAR penalty in head and body imaging at 7 Tesla. Y1 - 2010 U6 - http://dx.doi.org/10.1002/mrm.22527 SN - 1522-2594 VL - 64 IS - 2 SP - 327 EP - 333 PB - Wiley-Liss CY - New York ER -