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51.
Jia-Yi Feng Yan-Qing Xie Peng Zhang Qian Zhou Afsar Khan Zhi-Hong Zhou Xian-Song Xia Lu Liu 《Molecules (Basel, Switzerland)》2022,27(11)
Traditional Chinese Medicine is generally used as a decoction to guard health. Many active ingredients in the decoction are chemical ingredients that are not usually paid attention to in phytochemical research, such as polysaccharides, etc. Based on research interest in Chinese herbal decoction, crude polysaccharides from G. wilfordii (GCP) were purified to obtain two relatively homogeneous polysaccharides, a neutral polysaccharide (GNP), and an acid polysaccharide (GAP) by various chromatographic separation methods, which were initially characterized by GC-MS, NMR, IR, and methylation analysis. Studies on the hepatoprotective activity of GCP in vivo showed that GCP might be a potential agent for the prevention and treatment of acute liver injury by inhibiting the secretion levels of ALT, AST, IL-6, IL-1β, TNF-α, and MDA expression levels, increasing SOD, and the GSH-Px activity value. Further, in vitro assays, GNP and GAP, decrease the inflammatory response by inhibiting the secretion of IL-6 and TNF-α, involved in the STAT1/T-bet signaling pathway. 相似文献
52.
Shagufta Perveen Areej Mohammad Al-Taweel Nawal Al-Musayeib Ghada Ahmed Fawzy Afsar Khan Rashad Mehmood 《Natural product research》2015,29(7):615-620
Two new flavonol glycosides, brachysides C and D, together with three known flavonol glycosides, were isolated from the leaves of Caragana brachyantha. The structures of brachysides C and D were elucidated on the basis of detailed spectroscopic analysis as quercetin 5-O-[α-l-rhamnopyranosyl-(1 → 6)-β-d-glucopyranoside]-7-O-[α-l-rhamnopyranoside] and quercetin 5-O-[α-l-rhamnopyranosyl-(1 → 6)-β-d-glucopyranoside]-7-O-[α-l-rhamnopyranoside]-4′-O-[α-l-rhamnopyranoside], respectively. The presence of flavonol tetra- and triglycosides bearing a sugar moiety at position 5 was the first report from this genus Caragana. 相似文献
53.
This study focuses on the finite element analysis of thermoelastic field in a thin circular functionally graded material (FGM) disk subjected to a thermal load and an inertia force due to rotation of the disk. Due to symmetry, the FGM disk is assumed to have exponential variation of material properties in radial direction only. As a result of nonuniform coefficient of thermal expansion (CTE) and nonuniform temperature distribution, the disk experiences an incompatible eigenstrain which is taken into account. Based on the two dimensional thermoelastic theories, the axisymmetric problem is formulated in terms of a second order ordinary differential equation which is solved by finite element method. Some numerical results of thermoelastic field are presented and discussed for an Al2O3/Al FGM disk. The analysis of the numerical results reveals that the thermoelastic field in an FGM disk is significantly influenced by temperature distribution profile, radial thickness of the disk, angular speed of the disk, and the inner and outer surface temperature difference, and can be controlled by controlling these parameters. 相似文献
54.
B3LYP and MP2 calculations with the commonly-used 6-31+G(d) basis set predict qualitatively different structures for the Tyr–Gly conformer book1, which is the most stable conformer identified in a previous study. The structures differ mainly in the ψtyr Ramachandran angle (138° in the B3LYP structure and 120° in the MP2 structure). The causes for the discrepant structures are attributed to missing dispersion in the B3LYP calculations and large intramolecular BSSE in the MP2 calculations. The correct ψtyr value is estimated to be 130°. The MP2/6-31+G(d) profile identified an additional conformer, not present on the B3LYP surface, with a ψtyr value of 96° and a more folded structure. This minimum is, however, likely an artefact of large intramolecular BSSE values. We recommend the use of basis sets of at least quadruple-zeta quality in density functional theory (DFT), DFTaugmented with an empirical dispersion term (DFT-D) and second-order Møller-Plesset perturbation theory (MP2 ) calculations in cases where intramolecular BSSE is expected to be large. 相似文献
55.
Hussain J Ullah R Khan A Khan FU Muhammad Z Shah MR 《Natural product communications》2011,6(2):171-173
A new tricyclic clerodane-type diterpenoid, trivially named phlomeoic acid (1), was isolated from the methanolic extract of Phlomis bracteosa, together with two known compounds, ursolic acid and glutinol, isolated for the first time from this species. Their structures were elucidated by means of spectroscopic and mass spectrometric techniques and comparison with literature data. 相似文献
56.
A. M. Afsar N. M. L. Huq J. I. Song 《Archive of Applied Mechanics (Ingenieur Archiv)》2010,80(4):401-412
This study presents an analytical solution to elastic field in a roller-guided panel of symmetric cross-ply laminated composite
material. The mixed boundary value two-dimensional plane stress elasticity problem is formulated in terms of a single displacement
potential function. This reduces the problem to the solution of a single fourth order partial differential equation of equilibrium
as the other equilibrium equation is satisfied automatically. The solution is obtained in terms of an infinite Fourier series.
To present some numerical results, a panel of glass/epoxy laminated composite is considered and different components of stress
and displacement at different sections of the panel are presented graphically. To justify the present analytical solution,
it is compared with the finite element solution obtained by using the commercial software ANSYS. It is found that the two
solutions agree well with each other. This ensures that the formulation developed in this study based on the displacement
potential approach can be used to obtain analytical solution of an elastic field in structural elements of laminated composite
under any mode of boundary conditions prescribed in terms of either stress, displacement or any combination of these. 相似文献
57.
Ultimate method for unambiguous identification of all donors in epitaxial GaAs and related compounds
M. N. Afsar Kenneth J. Button A. Y. Cho H. Morkoc 《International Journal of Infrared and Millimeter Waves》1981,2(6):1113-1121
When epitaxial GaAs is grown by the method of molecular beam epitaxy (mbe) it would be p-type unless it is intentionally doped lightly during growth by using a particular substitutional donor atom. We have chosen the tin donor in this case to render the specimen n-type. Then the conventional far infrared photoconductivity technique is used to observe the 1s to 2p transition of the electron of the tin donor. The identity of the donor, the energy of the quantum transition as a function of applied magnetic field intensity, and the line shape characteristics of that particular donor then become unquestionable.Work supported by the U.S. Air Force Office of Scientific Research under Contract #AFOSR-78-3708-D.Supported by the National Science Foundation 相似文献
58.
Using a geometric model to study the structure of hadrons, baryons having one, two and three heavy quarks have been studied
here. The study reveals diquark structure in baryons with one and two heavy quarks but not with three heavy identical quarks. 相似文献
59.
The present work shows that the Co3+ coordination to the deprotonated pyridine-amide ligands orients the noncoordinated or hanging pyridine rings, thus furnishing a cleft in which Zn2+ ions coordinate. The building block approach points out a strategy to incorporate a Lewis acidic metal center in the periphery. This strategy has been used to synthesize Co3+-centered-Zn2+-peripheral heterobimetallic complexes. These heterobimetallic complexes have been thoroughly characterized including structural studies and have been successfully shown to catalyze the Beckmann rearrangement of the aldoximes and ketoxime to their respective amides. 相似文献
60.
Michael B. Hursthouse K. M. Abdul Malik Pradip K. Bakshi A. Afsar Bhuiyan M. Qamrul Ehsan Syed Z. Haider 《Journal of chemical crystallography》1996,26(11):739-745
Thiamine hydrochloride (vitamin B1) reacts with antimony trichloride in methanol to produce a crystalline compound which has been characterized as the salt 2[C12H18N4OS]·[Sb2Cl10] by X-ray crystallography. The compound crystallizes in the triclinic space group
,b=11.029(2),c=12.234(2) Å, =108.75(2), =102.67(2), =103.59(2)°,U=1041.52 Å3,D
c=1.80 g cm–3,Z=1. The crystal structure consists of discrete [C12H18N4OS]2+ cations and chloro bridged [Cl4Sb(-Cl)2SbCl4]4- anions in 2:1 ratio, held together by hydrogen bonds and electrostatic forces. 相似文献