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1.
TG and DSC were carried out on PMAA-net-POTM in order to elucidate the relation between the heterogeneity and the thermal changes; moreover, TG and DSC were carried out on PPOTMDM and PMAA to compare the results. The onset temperature in the last stage in the TG curve of PMAA-net-POTM increases as the concentrations of DMF and POTMDM in the polymerization decrease. This is explained in terms of plasticizers effects. A single peak due to fusion of POTM chains appears in the DSC curves of most copolymers. However, it is not seen in the DSC curves of copolymers with high heterogeneity. This is explained in terms of the freezing of POTM chains by frozen heterogeneous moieties.  相似文献   
2.
We investigated the in situ immobilization of ultrafine particles synthesized in a water/oil (w/o) microemulsion to silica for its possible application to supported metal catalysts. ZnS particles immobilized to silica by the ME method were consistent with those synthesized in a w/o microemulsion. Therefore, ZnS particles in a w/o microemulsion could be immobilized to silica without aggregation by this method. The relationship between the method of synthesizing Rh ultrafine particles in a w/o microemulsion and the diameter and diameter distribution of Rh particles immobilized to silica was studied. Rh-SiO(2) catalysts with a sharp diameter distribution could be prepared by immobilizing Rh-hydrazine complex particles because these complex particles would be very stable in a w/o microemulsion. The Rh particle diameters of Rh-SiO(2) catalysts prepared by changing the amount of silica produced were almost identical. Accordingly, the Rh particle diameter of Rh-SiO(2) catalysts could be controlled independently of Rh content by the ME method. Copyright 2001 Academic Press.  相似文献   
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Toda N  Ori M  Takami K  Tago K  Kogen H 《Organic letters》2003,5(3):269-271
[reaction: see text] A stereoselective total synthesis of (+)-benzastatin E (1) is described. The synthesis involves a diastereoselective Grignard addition to 2-acylindoline 2, which is derived from commercially available (S)-2-indolinecarboxylic acid (3). The unknown absolute configuration of (+)-1 is determined as (9S,10R).  相似文献   
5.
The proton dynamics in one-dimensional hydrogen-bonding system in molecular co-crystals of tetramethylpyrazine (TMP) with chloranilic acid (H2ca), as well as 2,6-dimethylpyrazine (DMP) with H2ca is studied by 35Cl NQR and 2H NMR spin-lattice relaxation measurements. No transfer motion of proton between the acid and base molecules is observed in DMP-H2ca, while the motion of the acid proton is excited in TMP-H2ca and the activation energy for the motion increases from 35 kJ mol???1 to 50 kJ mol???1 by the deuteration.  相似文献   
6.
The mean spherical model (MSM) equation has been solved for the aquare-well potential. Comparison of the MSM results with the simulation results shows the MSM radial distribution function and energy to be satisfactory in the liquid states.  相似文献   
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Experiments have been performed to investigate the freezing heat transfer characteristics in a return bend with a rectangular cross section. The experiments were carried out for two kinds of duct heights of 30 and 50 mm under the fixed size of 300 mm in duct width and 159 mm in curvature radius of convex wall. Both the convex and concave walls of a return bend were kept less than the freezing temperature of water. It was found that the freezing characteristics on the convex wall are markedly different from those on the concave wall of a return bend, and that the cooling temperature ratio is one of the most important parameters on the forced-convection freezing heat transfer in a return bend.  相似文献   
8.
Visual observations reveal a complicated flow in the liquid melt and a melting front configuration resulting from horizontal ice plate melting from above into a 20 wt% calcium chloride aqueous solution. The initial temperature of the ice plate and the mixture are both −5°C. Small scale “mountain and valley” structures (∼1 mm) appear on the flat melting front just after melting begins, which have been called “sharkskin”. Innumerable upward and downward flows appear near the sharkskin and are controlled by its “mountain and valley” structure. These typical flows will considerably promote the melting of the ice plate to be 30% larger as compared to the numerically predicted results assuming a flat melting front (i.e., without the sharkskin), and also by three times larger compared with the results for melting from below.  相似文献   
9.
Silica (SiO2)-coated ceria (CeO2) nanoparticles were prepared using water-in-oil microemulsion. Polyoxyethylene (15) cetylether and cyclohexane were used as a surfactant and organic solvent. SiO2-coated CeO2 nanoparticles were obtained by hydrolysis of metal alkoxide (tetraethylorthosilicate, TEOS) in the solution containing CeO2 precursor nanoparticles. The effects of CeO2 sources (Ce metal salt) and CeO2 particle-forming agents on the morphology of SiO2–CeO2 particles were investigated. Observation via transmission electron microscopy revealed that the type of particle-forming agent affected the nanoparticles' morphology and that CeO2 nanoparticles were spherically coated with SiO2 when using oxalic acid ((COOH)2) as a particle-forming agent of CeO2. Furthermore, the transmittance of the particles was high in the visible region (above 400 nm) and decreased in the ultraviolet region.  相似文献   
10.
Desilicated MTW zeolite was evaluated in methylation of 2-methylnaphthalene (2-MN) in a fixed-bed flow reactor at 450 °C. Mesoporous MTW was fabricated via a microwave-assisted desilication process using a harsh alkaline solution to improve the pore volume and the surface area. H-ZSM-12 zeolite was treated with 0.3 M of NaOH solution with different treatment times. Due to the harsh alkaline treatment, micropores were blocked by the deposition of the removed atoms. Due to the importance of methylnaphthalenes intermediates, modified MTW zeolites were evaluated in methylation of 2-MN. Methanol (MeOH), 2-MN and 1,3,5-trimethylbenzene (TMB) were fed to the reactor with a molar ratio of 15:15:70. Higher selectivity to 1-methylnaphthalene (1-MN) was observed rather than dimethylnaphthalene and trimethylnaphthalene with a yield of 13.6, 8 and 2.5 mol%, respectively. Moderate conversion up to 24.1 mol% was reached for 30 min reaction.  相似文献   
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