Papers by Keyword: Molecular Structure

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Authors: A.P. Othman, Amin Aadenan, Muhammad Mus Ab Anas, G.A. Gopir
Abstract: The topology of electron density is a sketch that gives a clear picture about electronic distribution and details information of natural molecular bonding. In quantum mechanics or particularly in quantum chemistry, the electron density is a measure of the probability of an electron occupying at any infinitesimal element of space surrounding at any given point.Studies about the topology of electron density in Cd0.5Zn0.5S at plane (101) were conducted by the application of density functional theory (DFT) within linear augmented plane wave (LAPW) by using the WIEN2k software. In this calculation, generalized gradient approximation (GGA) methods were used to calculate the exchange-correlation potential of the electrons. Based on this calculation, the topology of electron density were presented in a contour plot (2D) and also inarelief map plot (3D) in order to see the way electron density, ρ of Cd0.5Zn0.5S defines the gradient field and hence the bonding type. From these plots, we identified the bond paths that coincide with the contours of electron to suggest that Cd0.5Zn0.5S exhibited characteristics of covalent and a slightly ionic bond character.
Authors: Qing Hua Zeng, Ai Bing Yu, Gao Qing Max Lu
Abstract: Polymer nanocomposites are recognized as the next generation of polymer composites due to their exceptional properties. Understanding the molecular origin of the reinforcement mechanism is crucial to the development of such promising materials. This paper reports our recent molecular dynamic study on clay-based polyurethane nanocomposites. The effect of clay platelets on phase separation behavior of polyurethane, at the clay-polyurethane interface, is quantified in terms of molecular interactions, structure and dynamics. The results show that the nanoconfinement of polyurethane chains in clay gallery impedes the development of phase separation commonly observed in bulk polyurethane. The absence of phase separation of intercalated polyurethane is believed to be related to the competitive interactions among clay platelet, polyurethane and surfactant.
Authors: Liu Ting, Liu Juan, Yang Jian Qiong
Abstract: Pathological changes in animal models of autoimmune hepatitis and liver cells were similar to the mechanism of injury and viral hepatitis, the thesis of the active component of several common liver substances studied, wild chrysanthemum extract has anti-bacterial, anti-viral, pharmacological effects such as anti-inflammatory and immune liver and nerve protection, Dicliptera polysaccharide with excellent hepatoprotective activity of the liver that can be used as an adjunct to clinical medicine. Introduction
Authors: Shun Li, Qi Jun Yu, Jiang Xiong Wei, Ya Jun Ji
Abstract: The polycarboxylate water reducers(PCs) with different molecular structure were synthesized. The effects of molecular structure on their performance in cement paste were investigated. The results show that the PCs with a medium density of PEO side chain and/or a moderate molecular weight and its distribution have a higher dispersibility and a stronger dispersion retention stability at the same time, and that those PCs with a shorter PEO side chain exhibit a stronger dispersion retention stability. The PCs with a higher molecular weight, a lower density and/or a shorter length of PEO side chain are more easy to adsorb on the surface of cement particles. The earlier induction period is shortened while the dormant period is prolonged during the process of cement hydration in the presence of PCs. The PCs with a shorter PEO side chain show a stronger retarding effct. This effect is not very obvious with the decreasing molecular weight.
Authors: Jing Zhang, Jiang Long Yu, Huan Zhao, Jun Shuai Liu
Abstract: β-Sialonwhiskers which the molecular structuralformula of β-Sialonis Si3Al3O3N5(z = 3) were synthesized from fly ash and graphite under appropriate technological conditions by carbothermal reduction–nitridation process. The effects of carbon content, reaction temperature and reaction time on synthesis ofβ-Sialonwere analysed by XRD, SEM techniques. The results proved that, the condition of the carbon content over 80% is the best parameter to promote theβ-Sialon powder production. Compared to other kinds of temperature, 1430 °C is the optimal temperature to promoteβ-Sialon powder generation. Compared to 3h, holding time of 6h is promoting theβ-Sialon powder generation.The main morphology of β-Sialon was rod-like whisker.
Authors: Hai Yan Wang, Yu Wen Liu, Ji Feng Tian, Bin Sun, Shi Jie Huang
Abstract: The failure behavior of Poly (ether urethanes) in ozone atmosphere was investigated by FTIR, UV-Vis spectra and SEM analysis. It is found that some oxygen-containing groups such as the hydroxyl group and the carbonyl group increase first and then slightly decrease with the ozone oxidation time and the carbohydryl and ether bonds decrease slowly. After oxidation by ozone, the polyurethane molecule chains break on C-O in ether and urethane groups instead of chain crosslinking. In addition, ozone oxidization increases the color difference and lowers the UV light transparence of polyurethane.
Authors: Ming Liu, Jia Heng Lei, Xiao Di Du, Bo Huang
Abstract: The properties of polycarboxylate superplasticizers(PCs) are related to their structures. For better understanding the different properties between PCs, their structures should be examined. In this paper, three kinds of PCs are synthesized by radical copolymerization method. The structure and property of PCs are studied by means of high performance liquid chromatography, zeta potential, water reducing rate and fluidity of cement paste. The results show that the conversion rate of reaction monomers is over 97%, and the reaction monomers are fully in the polymerization. The ester-type PCs has a higher water reduction capacity than the ether-type. At the same dosage, the adsorption and dispersion ability of ester-type PCs are stronger than that of ether-type PCs, yet the ether-type PCs has better slump retention performance in the cement pastes.
Authors: Wu Jie Ge, Qun Shao, Hui Xu, Ya Li Wan
Abstract: The paper studied the change of the coal characteristics based on the influence of lignite naturally oxidated in air. The original lignite and lignite naturally oxidated under different time were analyzed by the FTIR technology. The reason that metamorphism of lignite was vulnerable by oxygen was analyzed from the side of coal molecular structure. It indicates that lignite of a low rank coal easily oxidated is mainly because lignite has more active groups in coal molecular such as methyl, methylene, hydroxyl, aromatic ether, oxygen button and ether key. In lignite molecular, side chains of aromatic ring structure unit is firstly oxidized. The bridge button or side chains of coal molecular structure unit are easily oxidized at the same time with the structure of the bridge between units fracturing oxidation. Number of aromatic hydrocarbons remains stable after oxidation. General trend of cycloparafin hydrocarbon as well as aliphatic hydrocarbon are gradually reduced over the oxidized time.
Authors: Ulmas Gafurov
Abstract: A modeling method is suggested on the basis of measurable structural and deformation parameters to estimate the interrelation between the interconnecting chains over amorphous segments conformation structure distribution and the elastic modulus in tension experimental value for a loaded oriented linear amorphous- crystalline polymer. Macromolecule chain pulling out value of polymer crystallite was defined using the Frenkel-Kontorowa’s dislocation model .
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