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261.
Impact of strain induced by polymer curing in benzocyclobutene embedded semiconductor nanostructures
Genziana Bussone Emmanouil Dimakis Raphael Grifone Andreas Biermanns Abbes Tahraoui Dina Carbone Lutz Geelhaar Tobias U. Schülli Ullrich Pietsch 《固体物理学:研究快报》2014,8(12):1007-1010
Polymers such as benzocyclobutene are commonly used as embedding materials for semiconductor nanostructures. During the curing process of the polymer up to 250 °C, a significant impact of strain can be induced on the embedded semiconductor material due to different thermal expansion coefficients. This strain has been revealed by X‐ray diffraction in free‐standing GaAs nanowires grown on a silicon substrate, embedded in a polymer matrix. It will be shown that this strain is released during the X‐ray irradiation if additionally an external static electric field is applied.
262.
Sergey Pasechnik Ildar Nasibullayev Dina Shmeliova Valentin Tsvetkov Liu Zhijian 《Liquid crystals》2013,40(10):1153-1165
We present an experimental study of thin liquid crystal (LC) layers under the action of a harmonically varied pressure gradient. Optical measurements were performed to register the linear oscillations of a nematic director related to homeotropic and homeoplanar (hybrid) initial states. In the latter case one of the inner surfaces of the rectangular channels was treated by ultraviolet light to provide a relatively weak planar anchoring. The optical response of hybrid and homeotropic LC cells under an oscillating pressure gradient was investigated in relation to on the amplitude and frequency of the pressure gradient. A hydrodynamic model is developed taking into account the LC polar anchoring strength and the surface viscosity responsible for a fast LC surface dynamics. Our estimates show that the thickness of the boundary layer corresponding to the surface viscosity does not exceed 10?6 m, and further experiments are needed with thinner LC cells and higher frequency oscillations to achieve a more precise value. An oscillating Poiseuille flow in the hybrid cell was found to be useful for characterizing elastic and viscous properties of a weakly anchoring LC surface layer in a fast surface dynamic process. 相似文献
263.
Abstract Fully acetylated 1-thio-β-D-glucopyranosyl esters of N-protected amino acids (4–13) were prepared in high yields by condensation of 2,3,4,6-tetra-O-acetyl-1-thio-β-D-glucopyranose (1) with a pentachlorophenyl esters of N-protected amino acids (2) in the presence of imidazole, or bN-protected amino acids (3) in the presence of DCC + imidazole. High tendency of the S-acyl aglycon group in 4–13 to undergo S → O and S → N migrations was demonstrated in reactions with several alcohols and amines. 相似文献
264.
265.
Nahed M. El-Enany Dina T. El-Sherbiny Amina A. Abdelal Fathalla F. Belal 《Journal of fluorescence》2010,20(2):463-472
A sensitive, simple and selective spectrofluorimetric method was developed for the determination of Lamotrigine (LMT) in pharmaceutical
formulations and biological fluids. The method is based on reaction of LMT with o-phthalaldehyde in presence of 2-mercaptoethanol in borate buffer of pH 9.8 to yield a highly fluorescent derivative that
is measured at 448 nm after excitation at 337 nm. The different experimental parameters affecting the development and stability
of the reaction product were carefully studied and optimized. The fluorescence-concentration plot was rectilinear over the
range of 0.1–1.0 μg ml−1 with lower limit of detection (LOD) 0.02 μg ml−1 and limit of quantification (LOQ) 0.06 μg ml−1 respectively. The proposed method was successfully applied to the the analysis of commercial tablets. Statistical comparison
of the results obtained by the proposed and reference method revealed no significant difference in the performance of the
two methods regarding the accuracy and precision respectively. The proposed method was further extended to the in-vitro and in-vivo determination of the drug in spiked and real human plasma. The mean percentage recoveries in spiked and real human plasma
(n = 3) were 95.78 ± 1.37 and 90.93 ± 2.34 respectively. Interference arising from co-administered drugs was also studied. A
proposal for the reaction pathway with o-phthalaldehyde was postulated. 相似文献
266.
Dina T. El-Sherbiny Dalia R. El-Wasseef Mohammed E. Abd El-Ghaffar Saadia M. El-Ashry 《Journal of fluorescence》2010,20(1):251-260
Simultaneous determination of two structurally related ß2 adrenergic receptor agonists namely, Ritodrine HCl (RTH) and Isoxsuprine HCl (ISP) was performed using coupling technique of synchronous fluorimetry and H-point standard addition method. Under optimum conditions, linear determination ranges were 1.48 – 14.80?×?10?6 mol L?1 and 1.54 – 15.44?×?10?6 mol L?1 for ISP and RTH respectively. RTH and ISP could be determined simultaneously without interference from each other when their concentration ratio varies from 5:1 to 1:5 in the mixed sample. The proposed method was applied to the determination of RTH and ISP in synthetic mixture of pharmaceutical samples, the accuracy and precision of the results were satisfactory. 相似文献
267.
Carbonyl(tetraisopropylcyclopentadienyl)copper has been synthesized and isolated and can be stored at room temperature for several days. [(C5HR4)Cu(CO)] (R = CHMe2) has been characterized by 1H and 13C NMR, C,H analysis, mass spectrometry, and IR spectroscopy. Its reaction with white phosphorus yields a mixture of [(C5HR4)Cu(η2-P4)] with edge-opened P4 coordinated to a CuIII atom and [(C5HR4)Cu(μ,η2:1-P4)Cu(C5HR4)] with an additional Cu(C5HR4) fragment coordinated to one atom of the P4 ligand (R = CHMe2). 相似文献