@article{KernSchelthoffMathieu2011, author = {Kern, Alexander and Schelthoff, Christof and Mathieu, Moritz}, title = {Probability of lightning strikes to air-terminations of structures using the electro-geometrical model theory and the statistics of lightning current parameters}, series = {Atmospheric Research. 104 (2011)}, journal = {Atmospheric Research. 104 (2011)}, publisher = {Elsevier}, address = {Amsterdam}, isbn = {0169-8095}, year = {2011}, language = {en} } @article{SchiffelsBaumannSelmer2011, author = {Schiffels, Johannes and Baumann, Marcus and Selmer, Thorsten}, title = {Facile analysis of short-chain fatty acids as 4-nitrophenyl esters in complex anaerobic fermentation samples by high performance liquid chromatography}, series = {Journal of Chromatography A. 1218 (2011), H. 34}, journal = {Journal of Chromatography A. 1218 (2011), H. 34}, publisher = {Elsevier}, address = {Amsterdam}, isbn = {0021-9673}, pages = {5848 -- 5851}, year = {2011}, language = {en} } @article{LustfeldPithanReissel2012, author = {Lustfeld, H. and Pithan, C. and Reißel, Martin}, title = {Metallic electrolyte composites in the framework of the brick-layer model}, series = {Journal of the European Ceramic Society}, volume = {32}, journal = {Journal of the European Ceramic Society}, number = {4}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0955-2219}, doi = {10.1016/j.jeurceramsoc.2011.10.017}, pages = {859 -- 864}, year = {2012}, abstract = {It is well known that the already large dielectric constants of some electrolytes like BaTiO₃ can be enhanced further by adding metallic (e.g. Ni, Cu or Ag) nanoparticles. The enhancement can be quite large, a factor of more than 1000 is possible. The consequences for the properties will be discussed in the present paper applying a brick-layer model (BLM) for calculating dc-resistivities of thin layers and a modified one (PBLM) that includes percolation for calculating dielectric properties of these materials. The PBLM results in an at least qualitative description and understanding of the physical phenomena: This model gives an explanation for the steep increase of the dielectric constant below the percolation threshold and why this increase is connected to a dramatic decrease of the breakdown voltage as well as the ability of storing electrical energy. We conclude that metallic electrolyte composites like BaTiO₃ are not appropriate for energy storage.}, language = {en} } @article{SpiessWilfriedAlvarezetal.2011, author = {Spiess, Elmar and Wilfried, Reichardt and Alvarez, Gerardo and Gottrup, Marcus and {\"O}hlschl{\"a}ger, Peter}, title = {An Artificial PAP Gene Breaks Self-tolerance and Promotes Tumor Regression in the TRAMP Model for Prostate Carcinoma}, series = {Molecular Therapy}, volume = {20}, journal = {Molecular Therapy}, number = {3}, publisher = {Elsevier}, address = {Amsterdam}, isbn = {1525-0016}, pages = {555 -- 564}, year = {2011}, language = {en} } @article{OlaruKowalskiSethietal.2012, author = {Olaru, Alexandra Maria and Kowalski, Julia and Sethi, Vaishali and Bl{\"u}mich, Bernhard}, title = {Exchange relaxometry of flow at small P{\´e}clet numbers in a glass bead pack}, series = {Journal of Magnetic Resonance (JMR)}, volume = {220}, journal = {Journal of Magnetic Resonance (JMR)}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1096-0856}, doi = {10.1016/j.jmr.2012.04.015}, pages = {32 -- 44}, year = {2012}, abstract = {In this paper we consider low P{\´e}clet number flow in bead packs. A series of relaxation exchange experiments has been conducted and evaluated by ILT analysis. In the resulting correlation maps, we observed a collapse of the signal and a translation towards smaller relaxation times with increasing flow rates, as well as a signal tilt with respect to the diagonal. In the discussion of the phenomena we present a mathematical theory for relaxation exchange experiments that considers both diffusive and advective transport. We perform simulations based on this theory and discuss them with respect to the conducted experiments.}, language = {en} } @article{FischerKowalskiPudasaini2012, author = {Fischer, Jan-Thomas and Kowalski, Julia and Pudasaini, Shiva P.}, title = {Topographic curvature effects in applied avalanche modelling}, series = {Cold Regions Science and Technology}, volume = {74-75}, journal = {Cold Regions Science and Technology}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1872-7441}, doi = {10.1016/j.coldregions.2012.01.005}, pages = {21 -- 30}, year = {2012}, abstract = {This paper describes the implementation of topographic curvature effects within the RApid Mass MovementS (RAMMS) snow avalanche simulation toolbox. RAMMS is based on a model similar to shallow water equations with a Coulomb friction relation and the velocity dependent Voellmy drag. It is used for snow avalanche risk assessment in Switzerland. The snow avalanche simulation relies on back calculation of observed avalanches. The calibration of the friction parameters depends on characteristics of the avalanche track. The topographic curvature terms are not yet included in the above mentioned classical model. Here, we fundamentally improve this model by mathematically and physically including the topographic curvature effects. By decomposing the velocity dependent friction into a topography dependent term that accounts for a curvature enhancement in the Coulomb friction, and a topography independent contribution similar to the classical Voellmy drag, we construct a general curvature dependent frictional resistance, and thus propose new extended model equations. With three site-specific examples, we compare the apparent frictional resistance of the new approach, which includes topographic curvature effects, to the classical one. Our simulation results demonstrate substantial effects of the curvature on the flow dynamics e.g., the dynamic pressure distribution along the slope. The comparison of resistance coefficients between the two models demonstrates that the physically based extension presents an improvement to the classical approach. Furthermore a practical example highlights its influence on the pressure outline in the run out zone of the avalanche. Snow avalanche dynamics modeling natural terrain curvature centrifugal force friction coefficients.}, language = {en} } @article{FateriHoetterGebhardt2012, author = {Fateri, Miranda and H{\"o}tter, Jan-Steffen and Gebhardt, Andreas}, title = {Experimental and Theoretical Investigation of Buckling Deformation of Fabricated Objects by Selective Laser Melting}, series = {Physics Procedia}, volume = {39}, journal = {Physics Procedia}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1875-3892}, doi = {10.1016/j.phpro.2012.10.062}, pages = {464 -- 470}, year = {2012}, abstract = {Although Selective Laser Melting (SLM) process is an innovative manufacturing method, there are challenges such as inferior mechanical properties of fabricated objects. Regarding this, buckling deformation which is caused by thermal stress is one of the undesired mechanical properties which must be alleviated. As buckling deformation is more observable in hard to process materials, silver is selected to be studied theoretically and experimentally for this paper. Different scanning strategies are utilized and a Finite Element Method (FEM) is applied to calculate the temperature gradient in order to determine its effect on the buckling deformation of the objects from experiments.}, language = {en} } @article{WernerTakenagaTakietal.2013, author = {Werner, Frederik and Takenaga, Shoko and Taki, Hidenori and Sawada, Kazuaki and Sch{\"o}ning, Michael Josef}, title = {Comparison of label-free ACh-imaging sensors based on CCD and LAPS}, series = {Sensors and Actuators B: Chemical (2012)}, volume = {177}, journal = {Sensors and Actuators B: Chemical (2012)}, publisher = {Elsevier}, address = {Amsterdam}, isbn = {0925-4005}, pages = {745 -- 752}, year = {2013}, abstract = {Semiconductor-based chemical imaging sensors, like the light-addressable potentiometric sensor (LAPS) or the pH-imaging sensor based on a charge-coupled device (CCD), are becoming a powerful tool for label-free imaging of biological phenomena. We have proposed a polyion-based enzymatic membrane to develop an acetylcholine (ACh) imaging sensor for neural cell-activity observations. In this study, a CCD-type ACh-imaging sensor and a LAPS-type ACh-imaging sensor were fabricated and the prospect of both sensors was clarified by making a comparison of their basic characteristics.}, language = {en} } @article{KirchnerOberlaenderSucoetal.2013, author = {Kirchner, Patrick and Oberl{\"a}nder, Jan and Suco, Henri-Pierre and Rysstad, Gunnar and Sch{\"o}ning, Michael Josef}, title = {Monitoring the microbicidal effectiveness of gaseous hydrogen peroxide in sterilisation processes by means of a calorimetric gas sensor}, series = {Food control}, volume = {31}, journal = {Food control}, number = {2}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0956-7135}, doi = {10.1016/j.foodcont.2012.11.048}, pages = {530 -- 538}, year = {2013}, abstract = {In the present work, a novel method for monitoring sterilisation processes with gaseous H2O2 in combination with heat activation by means of a specially designed calorimetric gas sensor was evaluated. Therefore, the sterilisation process was extensively studied by using test specimens inoculated with Bacillus atrophaeus spores in order to identify the most influencing process factors on its microbicidal effectiveness. Besides the contact time of the test specimens with gaseous H2O2 varied between 0.2 and 0.5 s, the present H2O2 concentration in a range from 0 to 8\% v/v (volume percent) had a strong influence on the microbicidal effectiveness, whereas the change of the vaporiser temperature, gas flow and humidity were almost negligible. Furthermore, a calorimetric H2O2 gas sensor was characterised in the sterilisation process with gaseous H2O2 in a wide range of parameter settings, wherein the measurement signal has shown a linear response against the H2O2 concentration with a sensitivity of 4.75 °C/(\% v/v). In a final step, a correlation model by matching the measurement signal of the gas sensor with the microbial inactivation kinetics was established that demonstrates its suitability as an efficient method for validating the microbicidal effectiveness of sterilisation processes with gaseous H2O2.}, language = {en} } @article{HardtMartinMeissburgeretal.1978, author = {Hardt, Arno and Martin, S. and Meißburger, J. and Retz, R. and Wimmer, J.}, title = {The cryopump system of the QQDDQ magnet spectrometer BIG KARL}, series = {Vacuum}, volume = {28}, journal = {Vacuum}, number = {10-11}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1879-2715 (E-Journal); 0042-207X (Print)}, doi = {10.1016/S0042-207X(78)80026-8}, pages = {483}, year = {1978}, abstract = {Cryopumps without liquid nitrogen shielding are used to provide a vacuum of 10-6 torr in the spectrometer. The vacuum system is subdivided in three sections that can be separated by valves. The first section (scattering chamber) has a volume of 60 l, two rotation transmissions with 35 cm dia and a sliding seal that allows a rotation of 160° without deteriorating the vacuum. The second section includes the vacuum chambers inside the magnets with 6 × 80 cm cross-section and a length of 1200 cm. The third section (detector box) has a volume of 4300 l and contains a moveable detector system. The gas inside the detector with a pressure of 760 torr is separated from the vacuum by a 15 μm mylar foil with an area of 300 cm2. The detector box can be valved off by a valve with the dimension of 10 × 100 cm. The layout of system is given. The instrumentation and the interlock system are described. First experiences with this system are presented.}, language = {en} }