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排序方式: 共有195条查询结果,搜索用时 875 毫秒
181.
Simion Corina A. Margineanu Romul M. Bolos Petru Patrascu Vasile 《Journal of Radioanalytical and Nuclear Chemistry》2021,330(3):619-629
Journal of Radioanalytical and Nuclear Chemistry - Determination of tritium along Danube River Banks, in shallow waters, from Bazia? to Sulina, led to an average value of 29 TU and to a slight... 相似文献
182.
Anton A. Goloborodko Corina Mayerhofer Alexander R. Zubarev Irina A. Tarasova Alexander V. Gorshkov Roman A. Zubarev Mikhail V. Gorshkov 《Rapid communications in mass spectrometry : RCM》2010,24(4):454-462
Estimation of false discovery rate (FDR) for identified peptides is an important step in large‐scale proteomic studies. We introduced an empirical approach to the problem that is based on the FDR‐like functions of sets of peptide spectral matches (PSMs). These functions have close values for equal‐sized sets with the same FDR and depend monotonically on the FDR of a set. We have found three of them, based on three complementary sources of data: chromatography, mass spectrometry, and sequences of identified peptides. Using a calibration on a set of putative correct PSMs these functions were converted into the FDR scale. The approach was tested on a set of ~2800 PSMs obtained from rat kidney tissue. The estimates based on all three data sources were rather consistent with each other as well as with one made using the target‐decoy strategy. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
183.
Flow of a Maxwell fluid between two side walls induced by a constantly accelerating plate 总被引:1,自引:0,他引:1
Waseem Akhtar Corina Fetecau Victor Tigoiu Constantin Fetecau 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2009,60(3):498-510
The unsteady flow of a Maxwell fluid induced by a constantly accelerating plate between two side walls perpendicular to the
plate is studied. Exact solutions for the velocity field are established by means of the Fourier sine transforms. The adequate
tangential stresses are also determined. The similar solutions for a Newtonian fluid are obtained as limiting cases of our
solutions. In the absence of the side walls, the similar solutions for the unsteady flow over an infinite flat plate are recovered.
Finally, for comparison, the velocity field in the middle of the channel and the shear stresses at the bottom wall and on
the side walls are plotted for different values of the material constants.
相似文献
184.
Curschellas C Keller R Berger R Rietzler U Fell D Butt HJ Limbach HJ 《Journal of colloid and interface science》2012,374(1):164-175
Foamed products are a popular class of food products. The mechanism of stabilization of the air bubbles is often only partially understood. The current study aims at better understanding the stabilization of air-water interfaces through the low molecular weight surfactant polyglycerol ester (PGE). We chose PGE films as an exemplary case for a non-equilibrium situation at an air-water interface--a situation that requires the development of new experimental techniques. Several different film preparation and transfer methods onto solid substrates have been tested. The films were then investigated by scanning force microscopy, and structural artifacts associated to the sample preparation were identified and discussed. In addition to the study of Langmuir monolayers and Gibbs adsorption layers, we have proposed a new approach to investigate the skins of foam bubbles. We thereby were able to determine that PGE indeed covers bubbles by a multilayer structure and that the pH plays a role in the structuring of the films. We show that a combination of different film preparation methods allows us to get an insight into the aggregation behavior of PGE at the air-water interface and thereby better understand the stabilization mechanism of this particular surfactant. 相似文献
185.
We introduce an algebraic operator framework to study discounted penalty functions in renewal risk models. For inter-arrival and claim size distributions with rational Laplace transform, the usual integral equation is transformed into a boundary value problem, which is solved by symbolic techniques. The factorization of the differential operator can be lifted to the level of boundary value problems, amounting to iteratively solving first-order problems. This leads to an explicit expression for the Gerber-Shiu function in terms of the penalty function. 相似文献
186.
The structural evolution of zirconia thin films and gel powders has been evaluated by X-ray diffraction. Maxima (r
1 and r
2) of the experimental radial distribution function RDF and the bond angles were determined and correlated with TGA (thermogravimetric analysis), DTA (differential thermal analysis) and MS (mass spectrometry). The results indicate that the topological short-range structure (<5 Å) of amorphous zirconia thin films, independent of drying temperature, resembles that of crystalline tetragonal ZrO2. In contrast, amorphous zirconia powder gels dried at temperatures below 120°C show atomic arrangements similar to that of tetragonal ZrO2. The structure of these gels annealed at temperatures between 165–340°C resembles a distorted tetragonal ZrO2, monoclinic-like structure. Zirconia powders and films contain crystalline tetragonal ZrO2 at 400°C. 相似文献
187.
Harshitha Barike Aiyappa Patrick Wilde Thomas Quast Justus Masa Corina Andronescu Yen‐Ting Chen Martin Muhler Roland A. Fischer Wolfgang Schuhmann 《Angewandte Chemie (International ed. in English)》2019,58(26):8927-8931
Determination of the intrinsic electrocatalytic activity of nanomaterials by means of macroelectrode techniques is compromised by ensemble and film effects. Here, a unique “particle on a stick” approach is used to grow a single metal–organic framework (MOF; ZIF‐67) nanoparticle on a nanoelectrode surface which is pyrolyzed to generate a cobalt/nitrogen‐doped carbon (CoN/C) composite nanoparticle that exhibits very high catalytic activity towards the oxygen evolution reaction (OER) with a current density of up to 230 mA cm?2 at 1.77 V (vs. RHE), and a high turnover frequency (TOF) of 29.7 s?1 at 540 mV overpotential. Identical location transmission electron microscopy (IL‐TEM) analysis substantiates the “self‐sacrificial” template nature of the MOF, while post‐electrocatalysis studies reveal agglomeration of Co centers within the CoN/C composite during the OER. “Single‐entity” electrochemical analysis allows for deriving the intrinsic electrocatalytic activity and furnishes insight into the transient behavior of the electrocatalyst under reaction conditions. 相似文献
188.
Tsvetan Tarnev Harshitha Barike Aiyappa Alexander Botz Thomas Erichsen Andrzej Ernst Corina Andronescu Wolfgang Schuhmann 《Angewandte Chemie (International ed. in English)》2019,58(40):14265-14269
“Single entity” measurements are central for an improved understanding of the function of nanoparticle‐based electrocatalysts without interference arising from mass transfer limitations and local changes of educt concentration or the pH value. We report a scanning electrochemical cell microscopy (SECCM) investigation of zeolitic imidazolate framework (ZIF‐67)‐derived Co?N‐doped C composite particles with respect to the oxygen evolution reaction (OER). Surmounting the surface wetting issues as well as the potential drift through the use of a non‐interfering Os complex as free‐diffusing internal redox potential standard, SECCM could be successfully applied in alkaline media. SECCM mapping reveals activity differences relative to the number of particles in the wetted area of the droplet landing zone. The turnover frequency (TOF) is 0.25 to 1.5 s?1 at potentials between 1.7 and 1.8 V vs. RHE, respectively, based on the number of Co atoms in each particle. Consistent values at locations with varying number of particles demonstrates OER performance devoid of macroscopic film effects. 相似文献
189.
Corina A. Olah 《PAMM》2007,7(1):2120017-2120018
We use a stabilized FEM with Gear time-stepping to study periodically forced internal flows. The time-periodically forced Navier-Stokes equations always admit a time-periodic solution but we show that this time-periodic solution might not be stable, even in 2-D. Numerical results are presented for a time-periodic lid driven cavity. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
190.
Pulsed field gradient NMR self-diffusion studies of water were used to determine surface-to-volume ratios and specific surface areas of the grains forming a glacial sand deposit. Both quantities exhibit a noninteger power-law dependence as a function of the diameters of the grains. The associated fractal dimensions of the surface area ( D(s)) and of the pore volume ( D(v)) are found to be D(s)-D(v) = -0.70+/-0.05 and D(s) = 2.20+/-0.05. The results demonstrate that NMR studies with native pore fluids are suitable to investigate the fractal nature of natural, unconsolidated porous materials. 相似文献