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排序方式: 共有474条查询结果,搜索用时 15 毫秒
1.
D. Amutha Rani Y. Yamamoto S. Mohri M. Sivakumar Y. Tsujita H. Yoshimizu 《Journal of Polymer Science.Polymer Physics》2003,41(3):269-273
In this study, a novel stepwise extraction method has been examined. The guest molecules housed between the helices of the clathrate δ form of syndiotactic polystyrene can be removed completely with this method. A systematic study of the preparation of a solvent‐free mesophase (emptied clathrate) membrane, its helical and residual solvent contents, and its structural transformations has been performed. In this first attempt, an enhancement in the TTGG helical content has been observed in the extracted membrane, and a conceptual mechanism is proposed. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 269–273, 2003 相似文献
2.
S. Mohri D. Amutha Rani Y. Yamamoto Y. Tsujita H. Yoshimizu 《Journal of Polymer Science.Polymer Physics》2004,42(2):238-245
Syndiotactic polystyrene (sPS) has various crystalline forms such as α, β, γ, and δ forms, and a mesophase depending on the preparation method. In this study, we focused on the mesophase with the molecular cavity of sPS, which is obtained by step‐wise extraction of the guest molecules from the sPS δ form. To prepare the mesophase containing different shapes and sizes of the cavity, two kinds of the sPS δ form membrane cast from either toluene or chloroform solution were first prepared and then the guest molecules were removed by a step‐wise extraction method using acetone and methanol. We could succeed in the preparation of two kinds of mesophase with different shapes and sizes of the molecular cavity. Either toluene or chloroform vapor sorption to the sPS mesophase membranes was examined at 25 °C. Sorption analysis indicates that the mesophase with large molecular cavities can mainly sorb large molecules; on the other hand, the mesophase with small cavities can sorb only the small molecules, and is unable to sorb a large amount of large molecule because the cavity was too small to sorb the large molecules. Therefore, the sPS mesophase membrane has sorption selectivity based on the size of the molecular cavity. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 238–245, 2004 相似文献
3.
Hard sphere diameters of liquid alkali metal alloys (Na-Cs and K-Rb) are calculated at 373 K ensuring the minimum Helmholtz
free energy of the system. These diameters are then used to fix the packing density of the alloy. On alloying, the hard sphere
diameters of Na in Na-Cs and K in K-Rb alloys expand whereas those of Cs and Rb contract. 相似文献
4.
The lattice dynamics of the b.c.c. lattice has been investigated using the central and the angular forces which are in general rotationally invariant. It has been observed that the four force constants are related to three elastic constants only. Dispersion curves for sodium were calculated and were found to be in excellent agreement with experiment. 相似文献
5.
Rani Siromoney Kamala Krithivasan Gift Siromoney 《Proceedings Mathematical Sciences》1973,78(2):72-88
Following the general linguistic approach proposed by Narasimhan to pattern recognition we proposed two generative models,viz., the matrix models and the more powerful two-dimensional array models. In this paper we generalize the matrix models ton-dimensions and establish that then-dimensional matrix models are closed under union, concatenation, Kleene closure, ∈-free homomorphism, inverse homomorphism and intersection with regular matrices. Symmetry operations such as translation, reflection and half-turn are examined. 相似文献
6.
Sangepu Bhavanarushi Zhi-Bin Luo Gandu Bharath JettiVatsala Rani Imran Khan Yin Xu Bin Liu Jimin Xie 《Journal of heterocyclic chemistry》2020,57(2):751-760
This paper investigates the seismic and collapse performance of shape memory alloy (SMA) braced steel frame structures considering the effects of various brace design parameters and ultimate state of SMAs. An SMA braced steel frame building is designed to have comparable strength and stiffness with a steel-moment resisting frame selected as case study building. Then, the stiffness and ultimate deformation capacity of the SMA braces in the initially designed reference SMA braced frame are systematically varied. First, the static pushover analysis and incremental dynamic analysis (IDA) are employed to illustrate the significance of SMA brace failure consideration in seismic performance assessment of steel frames with SMA elements. Then, the influence of SMA brace initial stiffness and ultimate deformation capacity on the seismic and collapse performance of SMA braced frames are studied through pushover analyses, nonlinear response history analyses, and IDA. The results show that the SMA brace initial stiffness does not affect the interstory drift and floor absolute acceleration response at design and maximum considered earthquake (MCE) level seismic hazard or collapse capacity of the frame. However, it has considerable influence on post-event functionality of the frame. It is also found that the SMA brace ultimate deformation capacity should be at least 80% of maximum inter-story drift demand at MCE level for satisfactory seismic performance, while larger values provide higher collapse capacity for the SMA braced frame. 相似文献
7.
Jhansi Rani Sunkara Sathish Mohan Botsa 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2020,94(2):392-400
Russian Journal of Physical Chemistry A - Recently the researchers have shown great interest on photocatalysis, especially in dyes degradation by nanocomposites under visible light. In this work,... 相似文献
8.
9.
Kathing C. Singh N. G. World Star Rani J. Nongrum R. Nongkhlaw R. 《Russian Journal of Organic Chemistry》2020,56(9):1628-1634
Russian Journal of Organic Chemistry - An efficient synthetic method for the highly selective synthesis of pharmacologically active 1,2-disubstituted benzimidazole derivatives... 相似文献
10.
Zeolites have taken a leading position in petrochemical, fine, and bulk chemical industries due to their porous architecture, pore sizes, tunable acidity, and thermal stability. Various strategies of zeolites preparation, including template‐free, solvent‐free, and toxic mineral‐free strategies are summarized. Moreover, the zeolite synthesis using naturally occurring minerals and sustainable natural templates is also discussed, which involves the synthesis of nanocrystalline zeolites of different framework structures using plant‐based natural templates and biomass‐derived renewable chemicals. Overall this personal account provides the fundamentals of various sustainable synthetic strategies reported in the literature for the synthesis of zeolites with suitable examples that will be useful for the students and will motivate experienced researchers to develop various novel sustainable methods for the synthesis of zeolites and other inorganic materials of industrial relevance. 相似文献