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11.
Mohsen K. Abou-Elregal Amira T. A. Mohamed Ahmed S. A. Youssef Magdy M. Hemdan Wael S. I. Abou-Elmagd 《合成通讯》2013,43(18):2347-2357
Reactions of 3-hyrazino-5,6-diphenyl-1,2,4-triazine with various carbonyl compounds such as ethyl acetoacetate, acetylacetone, benzoin, isatin, phthalic anhydride, phenyl isocyanate and acetic anhydride were discussed. Its reactions with α, β unsaturated compounds such as arylidinemalononitrile, diethyl acetylenedicarboxylate, dibenzylidine hydrazine were studied. These reactions led to the formation of various triazine and fused-triazine derivatives. The antitumor activity of the synthesized compounds was tested against HePG2 and MCF-7 cell lines. Some of the tested compounds were most active, whereas other compounds exhibited little or no activity. 相似文献
12.
Diffusion intermixing processes in nanostructured Ag/Sn thin-film system at room temperature were investigated by means of secondary neutral mass Spectrometry depth profiling technique. As it was confirmed by X-ray diffraction too, the reaction started already in the as-deposited sample. Since the bulk diffusion was frozen at room temperature, the Ag3Sn phase was formed along the grain boundaries (GBs), gradually consuming the interior of grains, and was grown perpendicular to the GBs. At the same time, formation and growth of a small compact reaction layer near the interface were observed and the shift of the bordering parallel interfaces was controlled by GB diffusion. From the kinetics of the diffusion process in the above two mechanisms, both the interface velocity in the diffusion-induced grain boundary motion regime as well as the coefficient of parabolic growth in the planar growth regime were determined. 相似文献
13.
14.
Garlic Powder as a Safe Environment Green Corrosion Inhibitor for Mild Steel in Acidic Media; Adsorption and Quantum Chemical Studies
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The corrosion inhibition of mild steel in H3PO4 solution by garlic powder was investigated using weight loss and polarization techniques. The adsorption of garlic powder was found to obey Langmuir adsorption isotherm. Maximum inhibition efficiency was 75% at 50 °C and 250 ppm inhibitor concentration. The values of heat of adsorption were negative indicating the spontaneous adsorption process. Quantum chemical calculations were used successfully to evaluate the theoretical inhibitor efficiency. Mathematical and statistical analyses were also used to represent the corrosion rate data with high correlation coefficients. Polarization measurements showed that garlic powder was a mixed — type inhibitor. 相似文献
15.
S. Abdallah T. A. El-Brolossy S. Negm H. Talaat 《The European physical journal. Special topics》2008,153(1):199-202
Photoacoustic absorption spectra of the
porous silicon samples (P-Si) of different thickness and porosity percentage
were measured at different modulation frequency. The absorption edge of the
P-Si layer for all samples shows a blue shift from that of crystalline
silicon (C-Si) at 1.1 eV. At low modulation frequency the estimated energy
gap (1.88 eV) is almost the same for all samples and the PA signal increases
as the porosity percentage increases. At the higher modulation frequency,
the spectra show an increase in the energy gap indicating the effect of
quantum confinement as the porosity increasing. The Raman shifts of the P-Si
samples are correlated with the particle size leading to an estimated
average particle size. The quantum confinement interpretation of the PA
results is in agreement with the Raman measurements that indicate the
presence of such nanostructure in the P-Si layer. 相似文献
16.
Understanding CHF is of an upmost importance in many industries, especially in the design and operation of boilers, nuclear power plants, cryogenic systems, etc. Due to safety issues related to the nuclear power plants, and the adaptation of CHF as the limiting criterion of power generation, it is important to understand the mechanisms of CHF relevant to nuclear systems operation. Moreover, CHF is expected to occur during transients than steady-state conditions. Therefore, knowledge of transient CHF is of great importance for the safety evaluation of nuclear reactors under transient condition. In this paper, the existing CHF experimental and modeling studies are discussed in order to understand the phenomena leading to CHF. Also, the effect of transient conditions on CHF for nuclear fuels has been evaluated. 相似文献
17.
T. A. El-Brolossy S. Abdallah T. Abdallah M. B. Mohamed S. Negm H. Talaat 《The European physical journal. Special topics》2008,153(1):365-368
We report on the optical absorption properties of as
prepared CdSe quantum dots (QDs) measured by the photoacoustic (PA) method.
CdSe QDs were fabricated by the chemical solution deposition (CD) technique.
With increasing growing time, the redshift of the PA spectra can be clearly
observed and optical absorption in the visible region due to CdSe Q-dots is
demonstrated. The average diameters of the CdSe QDs for each growth time
interval is estimated using the effective mass approximation giving
diameters ranging from 2.6 nm to 3.4 nm. These values are comparable to
those obtained by scanning tunnelling microscope (STM). Thus, PA
spectroscopy is useful to obtain the QDs sizes as grown and with no further
preparation. In addition, PA measurements provide also the thermal
diffusivity of samples of different sizes which in this case show an
increase by at least an order of magnitude than the bulk value. 相似文献
18.
Karolien De Wael Sandra Van Vlierberghe Hans Buschop Peter Dubruel Bart Vekemans Etienne Schacht Laszlo Vincze Annemie Adriaens 《Surface and interface analysis : SIA》2009,41(5):389-393
The aim of the present paper is to characterize a cross‐linked horse heart cytochrome c (HHC) film on cysteamine‐modified gold electrodes. The HHC film was deposited using 1‐ethyl‐3‐(3‐dimethylaminopropyl)‐carbodiimide (EDC) as a coupling agent. Attenuated total reflection infrared (ATR‐IR) spectroscopic analyses were performed to characterize the newly formed surface on a qualitative and conformational level. The film thickness was measured using a noncontact optical surface profiler, while quantitative data and information on the heterogeneity of the film were obtained by means of synchrotron radiation X‐ray micro fluorescence (SR micro‐XRF). Results indicate that, in addition to electrochemical studies, spectroscopic analysis methods are essential to gain insight in the effect of immobilization strategies on protein conformations. The latter is of relevance in the development and optimization of biosensors. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
19.
Wael Zaki 《Journal of the mechanics and physics of solids》2007,55(11):2427-2454
The model in the first part of this paper is extended to account for SMA behavior under cyclic loading. To this end, three new state variables are introduced: internal stress B, residual strain ?r and cumulated martensite volume fraction ze. Several parameters of the extended model depend on ze, making them evolve with cyclic phase change. Cyclic SMA effects including training and two-way shape memory are accounted for and several numerical simulations are provided and validated in the case of cyclic superelasticity. 相似文献