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21.
Abdel Raouf F. Elhefnawy Galal M. Moatimid Abd Elmonem Khalil Elcoot 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2004,86(2):63-91
The nonlinear electrohydrodynamic stability of
cylindrical interface, supporting surface charge, among two
conducting fluids is investigated. The two fluids are subjected to
a radial electric field. The analysis based on the multiple scale
technique. It is shown that the evolution of the amplitude is
governed by two partial differential equations. These equations
are combined to yield two alternate Schrödinger equations with
cubic nonlinearity. One of which calculates the nonlinear cutoff
electric field, separating stable and unstable disturbances, while
the other is used to analyze the stability of the system. The
stability criteria are analytically discussed and numerically
confirmed. Numerical calculations resulted in set of graphs to
indicate the stability picture of the considered system. 相似文献
22.
Amir Abbas Matin Ramin Maleki Mir Ali Farajzadeh Khalil Farhadi Reza Hosseinzadeh Abolghasem Jouyban 《Chromatographia》2007,66(5-6):383-387
A new method for extraction and analysis of acetone in human urine based on headspace solid phase microextraction using a
mixture of activated carbon and zeolite as sorbents in a PVC matrix coated on a silver wire and its application to the determination
of ketone bodies is described. Unlike commercial fibers, which are coated on fused silica, the coating adheres strongly to
the silver wire and is thermally stable up to 250 °C. After optimization of coating composition and microextraction conditions
the fiber was used for the analysis of acetone in human urine. 相似文献
23.
Muhammad Faisal Nobuaki Sato Armando T. Quitain Hiroyuki Daimon Koichi Fujie 《国际化学动力学杂志》2007,39(3):175-180
The kinetics and pathway of hydrothermal decomposition of aspartic acid were studied using a continuous‐flow tubular reactor. The reaction was carried out in the temperature range of 200–260°C and at a pressure of 20 MPa. Deamination was the primary reaction, indicated by the presence of significant amount of ammonia, fumaric acid, or maleic acid in the products. Other reaction products were pyruvic acid, malic acid, and traces of succinic and lactic acid. Traces of alanine were also detected, showing the possibility of decomposing high‐molecular weight amino acids to obtain simple amino acids such as glycine or alanine. Results on the effect of reaction parameters demonstrated that decomposition of aspartic acid is highly temperature dependent under hydrothermal conditions. For a slight temperature difference of 60°C (from 200 to 260°C), the first‐order reaction rate constants of 0.003 significantly increased to 0.231 s?1. The activation energy was 144 kJ/mol, as calculated by the Arrhenius equation. No significant effect was exhibited by other reaction parameters such as pH and pressure. The results are useful in controlling the hydrolysis of proteinaceous materials toward high yield of aspartic acid under hydrothermal conditions. © 2007 Wiley Periodicals, Inc. 39: 175–180, 2007 相似文献
24.
A. Saxena D. Fabris G. Prete D. V. Shetty G. Viesti B. K. Nayak D. C. Biswas R. K. Choudhury S. S. Kapoor M. Lunardon S. Moretto G. Nebbia S. Pesente V. Rizzi A. M. Samant M. Barbui E. Fioretto M. Cinausero A. Brondi G. La Rana R. Moro E. Vardaci N. Gelli F. Lucarelli 《Nuclear Physics A》2004,730(3-4):299-315
Pre-scission and post-scission multiplicities of neutrons and alpha particles have been simultaneously measured for the fission-like reactions of 340 MeV 28Si on 232Th. Dynamical model calculations using HICOL code predict that about 90% of the observed events are of quasi-fission type while the remaining 10% are from compound nucleus fission decay. Moving source fits were carried out to the observed neutron and alpha particle spectra, measured at different angles with respect to the fragment directions. The pre-scission and post-scission neutron multiplicities are deduced to be 8.7±2.0 and 9.4±2.0, respectively. The corresponding multiplicity values for alpha particles are found to be 0.22±0.08 and 0.1±0.03. From the measured post-scission neutron multiplicity, it is inferred that about 65±20 MeV of the initial excitation energy remains at scission. This may be compared to the value of 85±30 MeV estimated from PACE2 statistical model calculations, adjusted to reproduce the measured pre-scission neutron multiplicity. From a comparison of the Statistical Model predictions with the measured pre-scission neutron multiplicity, the fission delay is estimated to be of 5+7−3×10−20 s which overlaps with the average duration of fission-like process from the contact to the scission point (2×10−20 s) as determined from HICOL-based dynamical calculations. For the delay time deduced as above, the pre-scission alpha particle multiplicity calculated by the PACE2 code is about a factor two larger than the experimental one, demonstrating the difficulties in modelling the alpha particle emission from highly elongated shapes that characterize the fissioning system from the contact point to scission. 相似文献
25.
26.
Nanocrystalline thin films of copper selenide have been grown on glass and tin doped-indium oxide substrates using chemical method. At ambient temperature, golden films have been synthesized and annealed at 200 °C for 1 h and were examined for their structural, surface morphological and optical properties by means of X-ray diffraction (XRD), scanning electron microscopy and UV-vis spectrophotometry techniques, respectively. Cu2−xSe phase was confirmed by XRD pattern and spherical grains of 30 ± 4 - 40 ± 4 nm in size aggregated over about 130 ± 10 nm islands were seen by SEM images. Effect of annealing on crystallinity improvement, band edge shift and photoelectrochemical performance (under 80 mW/cm2 light intensity and in lithium iodide electrolyte) has been studied and reported. Observed p-type electrical conductivity in copper selenide thin films make it a suitable candidate for heterojunction solar cells. 相似文献
27.
Muhammad Taher Abuelma'atti 《International Journal of Infrared and Millimeter Waves》1995,16(2):391-400
A Fourier-series model describing the current-voltage characteristic of a quantum-well diode (QWD) is presented. Using this model, closed-form expressions are obtained for the harmonic and intermodulation performance of a QWD excited by a multisinusoidal voltage superimposed on a dc voltage. 相似文献
28.
Roshdi Khalil 《Annali di Matematica Pura ed Applicata》1990,157(1):245-249
Summary In this note we prove that: if T is a contraction in L(lp) that maps elements of disjoint support to elements of disjoint support, then T is an extreme point of the unit ball of L(lp), 1
i) form a p-orthonormal sequence or the nonzero elements of (yi) form a p-orthonormal sequence for which supp (yi)=N. 相似文献
29.
Hung‐Chuan Cheng Li‐Tang Wang Ashraf Taha Khalil Yao‐To Chang Yu‐Chi Lin Ya‐Ching Shen 《中国化学会会志》2004,51(2):431-435
Phytochemical investigation of the stem bark of Calophyllum inophyllum resulted in the isolation of a new dipyrenoxanthone, calophinone ( 1 ), together with four related xanthones ( 2–5 ). Identification of the isolated compounds was achieved through intensive studies of their spectral data, especially 2D NMR. 相似文献
30.
Dynamic Interfacial Tension Behavior of Water/Oil Systems Containing In situ-Formed Surfactants 总被引:1,自引:0,他引:1
Time-dependent interfacial tension (IFT) has been investigated for an interfacially reactive immiscible system composed of model-acidified oil and alkaline water. The acidified oil was composed of either lauric acid or linoleic acid dissolved in n-dodecane. Drop volume tensiometry was employed to measure the interfacial tension between the two phases. In the case of lauric acid, the IFT value was found to decrease sharply with increasing alkali concentration, even at low drop formation times. In the case of linoleic acid, the IFT decrease with the drop formation time was more gradual, especially at low alkali concentration. The rate of formation of the interfacial area was also found to be dependent on alkali concentration. 相似文献