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161.
Hamid Moghimi Amir Moradi Javad Hamedi Mina Basiri 《Applied biochemistry and biotechnology》2016,178(6):1207-1219
162.
Assembly of an Achiral Chromophore into Light‐Responsive Helical Nanostructures in the Absence of Chiral Components
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Prof. Dr. Mina Han Prof. Dr. Sung June Cho Dr. Yasuo Norikane Prof. Dr. Masaki Shimizu Prof. Dr. Takahiro Seki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(12):3971-3975
The chirality found in living organisms is one of unsolved mysteries on Earth. It is crucial to understand the manner in which small achiral molecules evolve into helical superstructures in the absence of chiral components because this process can provide important insights regarding the origin of chirality in nature. 1) the uncommon helical assembly of an achiral trigonal chromophore into helical nanostructures with aggregation‐induced emission enhancement (AIEE) characteristics and 2) the tunability of the helical pitch and fluorescence intensity in response to light is reported. The Rietveld refinement of X‐ray diffraction (XRD) patterns and the growth process suggest that a striking transformation from an achiral to an asymmetric molecule can occur as a result of specific interactions with certain solvents, presumably leading to the unique helical assembly. More importantly, exposure to UV or visible light promoted not only the formation of irregular helical structures with a wide range of pitch lengths but also an increase in fluorescence intensity. 相似文献
163.
Youssef Z. Boutros Mina B. Abd-el-Malek Nagwa A. Badran Hossam S. Hassan 《Meccanica》2006,41(6):681-691
The boundary-layer equations for two-dimensional steady flow of an incompressible, viscous fluid near a stagnation point at
a heated stretching sheet placed in a porous medium are considered. We apply Lie-group method for determining symmetry reductions
of partial differential equations. Lie-group method starts out with a general infinitesimal group of transformations under
which the given partial differential equations are invariant. The determining equations are a set of linear differential equations,
the solution of which gives the transformation function or the infinitesimals of the dependent and independent variables.
After the group has been determined, a solution to the given partial differential equations may be found from the invariant
surface condition such that its solution leads to similarity variables that reduce the number of independent variables of
the system. The effect of the velocity parameter λ, which is the ratio of the external free stream velocity to the stretching
surface velocity, permeability parameter of the porous medium k
1, and Prandtl number Pr on the horizontal and transverse velocities, temperature profiles, surface heat flux and the wall
shear stress, has been studied. 相似文献
164.
This paper is concerned with the initial boundary value problem for the p‐system with nonlinear damping and fixed boundary condition. We show that the corresponding problem admits a unique global solution, and such a solution tends time asymptotically to the corresponding nonlinear diffusion wave governed by the classical Darcy's law provided that the corresponding prescribed initial error function is sufficiently small. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
165.
Mina Saeedi Shirin Ansari Mohammad Mahdavi Reyhaneh Sabourian Tahmineh Akbarzadeh Alireza Foroumadi 《合成通讯》2013,43(20):2311-2318
A novel series of 1,2,3-triazole-dihydro[3,2-c]chromenone derivatives were synthesized through an efficient three-step reaction starting from 4-hydroxybenzaldehyde. All the newly synthesized compounds were characterized by infrared and NMR spectroscopy as well as elemental analysis and evaluated for their acetylcholinesterase inhibitory activity. 相似文献
166.
Dr. Riccardo Amorati Dr. Luca Valgimigli Dr. Peter Dinér Dr. Khadijeh Bakhtiari Dr. Mina Saeedi Prof. Lars Engman 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(23):7510-7522
Hydroxyaryl alkyl tellurides are effective antioxidants both in organic solution and aqueous biphasic systems. They react by an unconventional mechanism with ROO. radicals with rate constants as high as 107 M ?1 s?1 at 303 K, outperforming common phenols. The reactions proceed by oxygen atom transfer to tellurium followed by hydrogen atom transfer to the resulting RO. radical from the phenolic OH. The reaction rates do not reflect the electronic properties of the ring substituents and, because the reactions occur in a solvent cage, quenching is more efficient when the OH and TeR groups have an ortho arrangement. In the presence of thiols, hydroxyaryl alkyl tellurides act as catalytic antioxidants towards both hydroperoxides (mimicking the glutathione peroxidases) and peroxyl radicals. The high efficiency of the quenching of the peroxyl radicals and hydroperoxides could be advantageous under normal cellular conditions, but pro‐oxidative (thiol depletion) when thiol concentrations are low. 相似文献
167.
Masoud Salavati-Niasari Mina Gholami-Daghian Mahdiyeh Esmaeili-Zare Fatemeh Sadat Sangsefidi 《Journal of Cluster Science》2013,24(4):1093-1101
A novel and simple one-step solid state reaction in the presence of a suitable surfactant, sodium dodecyl sulfate (SDS), and a novel precursor, [bis(acetylacetonato)zinc(II)]; [Zn(acac)2]; has been developed to synthesize uniform zinc oxide microflakes with an average thickness of 0.3–2.4 μm. In the absence of SDS the product samples contained microrods. The formation of zinc oxide microflakes depends on the molar ratio of Zn(II)/SDS and the experimental procedure. The products were characterized by X-ray diffraction, photoluminescence spectroscopy, FT-IR spectroscopy, surface area, scanning electron microscopy and transmission electron microscopy to depict the phase and morphology. The synthesized ZnO microflakes have a hexagonal zincite structure. 相似文献
168.
Morteza Moradi Yadollah Yamini Moslem Tayyebi Hamid Asiabi 《Analytical and bioanalytical chemistry》2013,405(12):4235-4243
Novel ultrasonically enhanced supramolecular solvent microextraction (USESSM) then high-performance liquid chromatography with ultraviolet detection have been used for extraction and determination of phthalates in water and cosmetics. Coacervates consisting of decanoic acid-based nano-structured aggregates, specifically reverse micelles, have been used the first time as solvents for ultrasound-assisted emulsification microextraction (USAEME). Sonication accelerated mass transfer of the target analytes into the nano-structured solvent from the aqueous sample, thus reducing extraction time. Several conditions affecting extraction efficiency, for example the concentrations of major components of the supramolecular solvent (tetrahydrofuran and decanoic acid), sample solution pH, salt addition, and ultrasonication time, were investigated and optimized. Under the optimum conditions, preconcentration of the analytes ranged from 176 to 412-fold and the linear range was 0.5–100 μg?L?1, with correlation coefficients (R 2)?≥?0.9984. The detection sensitivity of the method was excellent, with limits of detection (LOD, S/N?=?3) in the range 0.10–0.70 μg?L?1 and precision in the range 4.1–11.7 % (RSD, n?=?5). This method was successfully used for analysis of phthalates in water and cosmetics, with good recovery of spiked phthalates (91.0–108.5 %). 相似文献
169.
The present paper reports a comprehensive and complementary study on structural, electronic and phonon properties of face centered cubic fluorites, namely CaF2, BaF2 and SrF2, using first principles density functional calculations within the generalized gradient approximation. The calculated lattice constants and bulk modulus are in good agreement with available experimental data. The analysis of band structure and density of states confirms the ionic character for all the three fluorides. The phonon dispersion curves and corresponding phonon density of states obtained in the present work are consistent with the available experimental and other theoretical data. The LO-TO splitting is maximum for CaF2, which confirms that the ionicity is maximum in the case of CaF2. The phonon properties for SrF2 have been calculated for the first time. 相似文献
170.
A technique is developed and luminescence quenching of complexes immobilized on cation-exchange membranes is considered. The
mechanism of the luminescence quenching of the complexes by molecular oxygen is discussed. 相似文献