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121.
Hf(1-x)Lu(x)W(2)O(8-y) solid solutions up to x = 0.04, based on a negative thermal expansion material HfW(2)O(8), were synthesized by a solid state reaction method. X-ray diffraction experiments of these solid solutions from 90 to 560 K indicated thermal contraction with increasing temperature. Temperatures of order-disorder phase transition (T(trs)) associated with the orientation of WO(4) tetrahedra were determined from disappearance of a characteristic diffraction peak (310). The T(trs) of the solid solutions drastically decreased with increasing Lu content. Saturated order parameters (eta(s)) associated with the orientational order of the WO(4) pairs were estimated from the characteristic diffraction peak at sufficient low temperature. These behaviors of Hf(1-x)Lu(x)W(2)O(8-y) are consistent with those of Zr(1-x)M(x)W(2)O(8-y) (M = Sc, Y, In, Lu). The drastic suppression of T(trs) in Hf(1-x)Lu(x)W(2)O(8-y) can be interpreted in the framework of a model proposed for Zr(1-x)M(x)W(2)O(8-y), which states the existence of a local nanoregion including the WO(4) pairs having the frozen-in orientational disorder. To understand the substitution effect on the order-disorder phase transition comprehensively, classification based on the saturated order parameter eta(s) of the phase transition of AW(2)O(8) (A = Hf, Zr)-based solid solutions was carried out and discussed. 相似文献
122.
Thermally reversible polyesters were obtained by the ester formation reaction of thermoplastic polyesters with hydroxyl end groups and the diacid anhydride of tetra carboxylic acid as a thermally reversible chain extender. Typical example of the thermally reversible polyesters was obtained by the reaction of PBT (polyburylene terephthalate) and PMA (pyromellitic dianhydride). This material having twice as large molecular weight as the original PBT exhibited almost the same melt viscosity as the original. Also that thermally reversible chain extension reaction occurred without unfavorable side reaction such as cross-linking. This material shows both good processability and superior mechanical properties due to its thermally reversible characters. 相似文献
123.
Toshihide Baba 《Catalysis Surveys from Japan》2000,4(1):17-29
This review describes the preparation, characterization and application of KNH2 loaded on alumina and KF loaded on alumina. These strong solid bases catalyze a variety of organic reactions in a very selective manner. The reactions include isomerizations of alkenes and alkynes, dimerization of alkynes, Tishchenko reaction, and the reaction of silanes to form of Si–C, Si–N and Si–O bonds. 相似文献
124.
Mihaya Kotajima Jae-Hoon Choi Mitsuru Kondo Corina N. DAlessandro-Gabazza Masaaki Toda Taro Yasuma Esteban C. Gabazza Yukihiro Miwa Chiho Shoda Deokho Lee Ayaka Nakai Toshihide Kurihara Jing Wu Hirofumi Hirai Hirokazu Kawagishi 《Molecules (Basel, Switzerland)》2022,27(24)
Two compounds 1 and 2 were isolated from the culture broth of Lepista luscina. This is the first time that compound 1 was isolated from a natural source. The structure of compound 1 was identified via 1D and 2D NMR and HRESIMS data. Compounds 1 and 2 along with 8-nitrotryptanthrin (4) were evaluated for their biological activities using the A549 lung cancer cell line. As a result, 1 and 2 inhibited the expression of Axl and immune checkpoint molecules. In addition, compounds 1, 2 and 4 were tested for HIF inhibitory activity. Compound 2 demonstrated statistically significant HIF inhibitory effects on NIH3T3 cells and 1 and 2 against ARPE19 cells. 相似文献
125.
126.
Using Grand Canonical Monte Carlo simulation, we have studied the effects of confinement on argon and methanol adsorption in graphitic cylindrical and slit pores. Linear chain, zigzag and incomplete helical packing are observed for argon adsorption in cylindrical pores. However, for methanol adsorption different features appear because the electrostatic interactions favour configurations that maximize the hydrogen bonding among methanol molecules. We have found zigzag chains with hydrogen-bonded structures for methanol adsorption in cylindrical and slit pores. To investigate how dense the adsorbed phase is and how many molecules could be packed per unit physical volume of the solid, we consider two different definitions of pore density; one based on the physical volume and the other on the accessible volume. That based on accessible volume gives a measure of the fluid density, while that based on the physical volume gives a measure of how much adsorbate can be stored per unit volume of the adsorbent. It is found that the adsorbate is denser in cylindrical pores, but that slit pores can pack more molecules per unit solid volume. We also discuss the effects on the isosteric heat of argon and methanol of pore size, pore geometry and loading. 相似文献
127.
K Tanaka T Muraoka D Hirayama A Ohnish 《Chemical communications (Cambridge, England)》2012,48(68):8577-8579
Enantiomeric resolution of various sulfoxides using a homochiral MOF-silica composite as a new chiral stationary phase for HPLC has been successfully demonstrated. 相似文献
128.
Toshihide Ibaraki Takashi Imamichi Yuichi Koga Hiroshi Nagamochi Koji Nonobe Mutsunori Yagiura 《Mathematical Programming》2011,127(2):297-343
MAX-2-SAT is one of the representative combinatorial problems and is known to be NP-hard. Given a set of m clauses on n propositional variables, where each clause contains at most two literals and is weighted by a positive real, MAX-2-SAT asks
to find a truth assignment that maximizes the total weight of satisfied clauses. In this paper, we propose branch-and-bound
exact algorithms for MAX-2-SAT utilizing three kinds of lower bounds. All lower bounds are based on a directed graph that
represents conflicts among clauses, and two of them use a set covering representation of MAX-2-SAT. Computational comparisons
on benchmark instances disclose that these algorithms are highly effective in reducing the number of search tree nodes as
well as the computation time. 相似文献
129.
130.
Saito Naoki Saito Takeshi Yamazaki Taichi Fujimine Yoshinori Ihara Toshihide 《Accreditation and quality assurance》2017,22(4):171-178
Accreditation and Quality Assurance - Recently, it has become possible to examine metabolism abnormalities by detecting increases in specific acylcarnitines in blood tests of newborn babies using... 相似文献