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排序方式: 共有252条查询结果,搜索用时 15 毫秒
31.
Sorber J Steiner G Schulz V Guenther M Gerlach G Salzer R Arndt KF 《Analytical chemistry》2008,80(8):2957-2962
The strong swelling ability of the pH-responsive poly(acrylic acid)/poly(vinyl alcohol) (PAA/PVA) hydrogel makes the development of a new type of sensor possible, which combines piezoresistive-responsive elements as mechanoelectrical transducers and the phase transition behavior of hydrogels as a chemomechanical transducer. The sensor consists of a pH-responsive PAA/PVA hydrogel and a standard pressure sensor chip. However, a time-dependent sensor output voltage mirrors only the physical swelling process of the hydrogel but not the corresponding chemical reactions. Therefore, an investigation of the swelling behavior of this hydrogel is essential for the optimization of sensor design. In this work, Fourier transform infrared (FT-IR) spectroscopic imaging was used to study the swelling of the hydrogel under in situ conditions. In particular, laterally and time-resolved FT-IR images were obtained in the attenuated total reflection mode and the entire data set of more than 80,000 FT-IR spectra was evaluated by principal component analysis (PCA). The first and third principal components (PCs) indicate the swelling process. Molecular changes within the carboxyl groups were observed in the second and fourth PC and identified as key processes for the swelling behavior. It was found that time-dependent molecular changes are similar to the electrical sensor output signal. The results of the FT-IR spectroscopic images render an improved chemical sensor possible and demonstrate that in situ FT-IR imaging is a powerful method for the characterization of molecular processes within chemical-sensitive materials. 相似文献
32.
Three‐dimensional high‐resolution numerical simulations of a gas–solid jet in a high‐density riser flow were conducted. The impact of gas–solid injection on the riser flow hydrodynamics was investigated with respect to voidage, tracer mass fractions, and solids velocity distribution. The behaviors of a gas–solid jet in the riser crossflow were studied through the unsteady numerical simulations. Substantial separation of the jetting gas and solids in the riser crossflow was observed. Mixing of the injected gas and solids with the riser flow was investigated and backmixing of gas and solids was evaluated. In the current numerical study, both the overall hydrodynamics of riser flow and the characteristics of gas–solid jet were reasonably predicted compared with the experimental measurements made at NETL. Published 2011 American Institute of Chemical Engineers AIChE J, 2012 相似文献
33.
D. Guenther T. Kempf A. Ishaque G. Ascheid 《Analog Integrated Circuits and Signal Processing》2012,73(2):597-612
In this paper, we analyze the potential as well as the limitations of multiprocessor system-on-chip (MPSoC) platforms when implementing software defined radio (SDR) applications for wireless communications. Suitable MPSoCs contain a potentially heterogeneous multi-core computing cluster and can be further equipped with application specific accelerators. The physical layer of a MIMO OFDM transceiver, for which the IEEE 802.11n standard serves as reference, is investigated in this work. To maintain portability, the platform independent algorithmic kernels (Nuclei) are identified first. In the following case study, efficient implementations (Flavors) of these Nuclei are implemented on an MPSoC platform. Resultant algorithmic performance (e.g., frame-error-rate) as well as the system performance (e.g., latency and throughput) are discussed. 相似文献
34.
Ulla Seibel-Ehlert Nicole Plank Asuka Inoue Guenther Bernhardt Andrea Strasser 《International journal of molecular sciences》2021,22(18)
G protein activation represents an early key event in the complex GPCR signal transduction process and is usually studied by label-dependent methods targeting specific molecular events. However, the constrained environment of such “invasive” techniques could interfere with biological processes. Although histamine receptors (HRs) represent (evolving) drug targets, their signal transduction is not fully understood. To address this issue, we established a non-invasive dynamic mass redistribution (DMR) assay for the human H1–4Rs expressed in HEK cells, showing excellent signal-to-background ratios above 100 for histamine (HIS) and higher than 24 for inverse agonists with pEC50 values consistent with literature. Taking advantage of the integrative nature of the DMR assay, the involvement of endogenous Gαq/11, Gαs, Gα12/13 and Gβγ proteins was explored, pursuing a two-pronged approach, namely that of classical pharmacology (G protein modulators) and that of molecular biology (Gα knock-out HEK cells). We showed that signal transduction of hH1–4Rs occurred mainly, but not exclusively, via their canonical Gα proteins. For example, in addition to Gαi/o, the Gαq/11 protein was proven to contribute to the DMR response of hH3,4Rs. Moreover, the Gα12/13 was identified to be involved in the hH2R mediated signaling pathway. These results are considered as a basis for future investigations on the (patho)physiological role and the pharmacological potential of H1–4Rs. 相似文献
35.
Dipl.-Phys. Andreas Neuber M. Sc. Guenther Carlos Krieger Dipl.-Ing. Markus Tacke Prof. Dr.-Ing Johannes Janicka 《Forschung im Ingenieurwesen》1996,62(7-8):188-194
Zusammenfassung Die laserspektroskopischen Me?methoden laserinduzierte Fluoreszenz und spontane Ramanspektroskopie werden eingesetzt zur Messung
der Konzentrationen von Stickoxid, Hydroxyl sowie der chemischen Hauptkomponenten und der Temperatur. Betrachtet wird die
thermische Umsetzung von Wasserstoff mit Luftsauerstoff. Es wird die experimentelle Vorgehensweise und Problematik dargestellt.
Ebenso wird der Weg der Modellierung und Berechnung turbulenter Verbrennungsvorg?nge am konkreten Beispiel skizziert. Die
Annahme chemischen Gleichgewichts stellt sich als ungenügend in der Berechnung der Stickoxid- und Hydroxylkonzentrationen
heraus. Eine deutlich bessere Vorhersage wird durch Einführen einer Reaktionsfortschrittsvariablen für das chemische Modell
erreicht. 相似文献
36.
M. Foerste H. Guenther O. Riediger J. Wiebe G. zu Putlitz 《Journal of Low Temperature Physics》1998,110(1-2):231-236
Mobility measurements of alkali-earth ions Be
+
, Mg
+
, Ca
+
, Sr
+
and Ba
+
in the temperature range 1.27 to 1.66 K are presented. The mobility of Be
+
shows a different behavior in comparison to that of Mg
+
, although the properties of the two elements are similar. This may suggest that Be
+
forms an alternate structure, perhaps a snowball, compared to the bubble like defect of Mg
+
. 相似文献
37.
38.
The temperature dependence of acoustic shear velocities are reported for Poly-Penco nylon, type G Plexiglass [poly(methyl methacrylate)], TFE Teflon (tetrafluoroethylene), low- and high-density polyethylene, Lexan (polycarbonate), and Delrin Acetal (nylon). Most of the data were obtained at a frequency of 1 Mc./sec. over the temperature range of 25–100°C. In addition, previously unreported longitudinal velocities to ~125°C. are reported for Lexan and Delrin Acetal. 相似文献
39.
Ultrasonic longitudinal wave velocities in layered materials were measured as a function of the lamination angle at several temperatures. It was found that the longitudinal wave velocity versus lamination angle curve maintains the same shape (for a given material) for temperatures between 25 and 125°C. Furthermore, it was found that the wave velocity versus lamination angle curve can be predicted to within 2% by a theoretical equation involving only the lamination angle, & thetas; (taken as the angle between the grain of the sample and the direction of sound propagation); c (0°), the measured wave velocity at an angle of 0°; and c (90°) the measured wave velocity at an angle of 90°. Finally, it was found that the longitudinal wave velocity of certain materials varies as much as 25% between lamination angles of 0° and 90°, while other materials show less variation, and some none at all. 相似文献
40.
Iam Choon Khoo Min-Yi Shih Wood M.V. Guenther B.D. Pao Hsu Chen Simoni F. Slussarenko S.S. Francescangeli O. Lucchetti L. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》1999,87(11):1897-1911
The basic mechanisms of photo-induced space charge field formation, director axis re-orientation, and refractive index changes in fullerene C60- and dye-doped nematic liquid crystals films are presented. In particular, in aligned methyl-red-doped nematic liquid crystal film, we observe a nonlinear index change coefficient as high as 10 cm2/W, associated with purely optically induced liquid crystal director axis re-orientation. Experimental observations of dynamic and high-resolution storage holographic grating formation, two beam coupling with gain of nearly 3000 cm-1, optical limiting action at nanowatt cw laser power, and incoherent-coherent image conversion at μW/cm2 light intensity level are discussed 相似文献