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991.
Three kinds of polyamides were synthesized from three diamines and 1,3,5‐benzenetricarbonyl trichloride (TMC). The diamines used were m‐phenylene diamine, N‐methyl‐m‐phenylenediamine, and N,N′‐dimethyl‐m‐phenylenediamine. The average free volume sizes of the polyamides were measured by positron annihilation lifetime spectroscopy (PALS), and the free volume fractions were evaluated by molecular dynamics (MD) simulations. The methyl substitution on amino groups of diamines brought about an increase in interstitial space of molecular chains of the polyamides. In addition, reverse osmosis (RO) membranes were prepared by interfacial polymerization from the three diamines and TMC. The increase in the degree of methyl‐substitution of diamines led to increased chlorine resistance and decreased salt rejections of the polyamide RO membranes. Thus, the methyl‐substitution of diamines significantly influenced membrane performance. The vacancy sizes and fractional volumes in polyamides evaluated by PALS measurement and MD simulation were well correlated with salt rejection of polyamide RO membranes. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
992.
Glycerol polyglycidyl ether (GPE) and polyglycerol polyglycidyl ether (PGPE) were cured with ε‐poly(L ‐lysine) (PL) using epoxy/amine ratios of 1 : 1 and 2 : 1 to create bio‐based epoxy cross‐linked resins. When PGPE was used as an epoxy resin and the epoxy/amine ratio was 1 : 1, the cured neat resin showed the greatest glass transition temperature (Tg), as measured by differential scanning calorimetry. Next, the mixture of PGPE, PL, and montomorillonite (MMT) at an epoxy/amine ratio of 1 : 1 in water was dried and cured finally at 110°C to create PGPE‐PL/MMT composites. The X‐ray diffraction and transmission electron microscopy measurements revealed that the composites with MMT content 7–15 wt % were exfoliated nanocomposites and the composite with MMT content 20 wt % was an intercalated nanocomposite. The Tg and storage modulus at 50–100°C for the PGPE‐PL/MMT composites measured by DMA increased with increasing MMT content until 15 wt % and decreased at 20 wt %. The tensile strength and modulus of the PGPE‐PL/MMT composites (MMT content 15 wt %: 42 and 5300 MPa) were much greater than those of the cured PGPE‐PL resin (4 and 6 MPa). Aerobic biodegradability of the PGPE‐PL in an aqueous medium was ~ 4% after 90 days, and the PGPE‐PL/MMT nanocomposites with MMT content 7–15 wt % showed lower biodegradability. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
993.
The effects of oxygen supply conditions and specific biofilm interfacial area on the phenol removal rate in a three‐phase fluidized bed bioreactor were evaluated. The experimental data were well‐explained by the semi‐theoretical equation based on the assumption that the reaction rate follows first‐order reaction kinetics with respect to oxygen and zero‐order one with respect to phenol. Two cases, biological reaction as rate‐controlling step and oxygen absorption as rate‐controlling step, were both explicable by this semi‐theoretical equation. The maximum volumetric phenol removal rate was 27.4 kg·m?3·d?1. 相似文献
994.
The southern cowpea weevil, Callosobruchus chinensis (Coleoptera: Bruchidae), is a major pest of stored legumes in warm temperate and tropical climates. The female sex attractant
pheromone was extracted from filter-paper shelters taken from containers that housed virgin females. The extracts were purified
by various chromatographic techniques, and the biologically active components in the fractions were screened by gas chromatographic–electroantennographic
detection analysis with male antennae. Two compounds that elicited electrophysiological responses were isolated, and gas chromatography–mass
spectrometry, nuclear magnetic resonance, and micro-chemical analyses suggested that the active compounds were homofarnesals,
(2Z,6E)- and (2E,6E)-7-ethyl-3,11-dimethyl-2,6,10-dodecatrienals. Males of C. chinensis were significantly attracted to filter paper discs loaded with the synthetic compounds at 0.01–0.1 ng compared to solvent
control in a Y-tube olfactometer assay. These pheromone components represent unique chemical structures within the genus Callosobruchus. 相似文献
995.
Hidetaka Uehara Tomomi Suganuma Satoshi Negishi Yukihiro Uda Yoshinori Furukawa Satoru Ueno Kiyotaka Sato 《Journal of the American Oil Chemists' Society》2008,85(1):29-36
Thermal properties, powder X-ray diffraction patterns and FT-IR absorption spectra of crystals of two isomers of conjugated
linoleic acid (CLA), 9-cis, 11-trans-CLA (c9t11), 10-trans, 12-cis-CLA (t10c12) were examined. To search for polymorphic modifications, we carefully performed crystallization from melt and
solution phases, and isolated one type of crystalline form in c9t11 and t10c12. The melting temperature (T
m) was 14.9 °C, enthalpy of fusion (ΔH) was 38.7 kJ/mol, and entropy of fusion (ΔS) was 134 J/mol K for c9t11, and T
m = 19.8 °C, ΔH = 35.6 kJ/mol and ΔS = 122 J/mol K for t10c12. The X-ray diffraction and FT-IR measurements indicated O⊥ subcell packing in the crystals of c9t11 and t10c12, and long spacing values of 4.22 nm for c9t11 and 3.88 nm for t10c12.
The unique molecular structures of the two isomers of CLA are discussed in comparison to the polymorphism of oleic acid, petroselinic
acid, elaidic acid and linoleic acid, all of which are unsaturated fatty acids having the same carbon number of 18 as that
of the two CLA isomers. 相似文献
996.
研究一种典型的微尺度康铜线/聚合物膜结构在力电耦合作用下的屈曲行为。根据卸载后康铜线从聚合物基底上屈曲的现象,评估康铜线与聚合物基底间的界面韧性。此外,力电耦合作用还会诱发新的失稳模态。在电载荷和拉伸载荷作用下,康铜线易在屈曲时发生断裂。在电载荷和压缩载荷作用下,康铜线易在屈曲区域的顶部发生折叠,偶尔还会向聚合物基底内部方向发生屈曲。分析了这些失稳模态的产生机理。 相似文献
997.
The microstructure of electrodeposited Zn-SiO2 composites before and after corrosion tests has been studied by using scanning electron microscopy-energy dispersive X-ray spectroscopy, X-ray diffraction and X-ray photoelectron spectroscopy. As-deposited Zn-SiO2 composites are composed of SiO2-rich and SiO2-poor phases. After a wet and dry cyclic corrosion test, including NaCl solution spray, zinc hydroxychloride is formed on the SiO2-rich phase which surrounds the uncorroded SiO2-poor phase. Zinc hydroxide, zinc oxide and zinc hydroxychloride are also formed on the surface of the Zn-SiO2 composites. The high corrosion resistance of the composites is attributed to the formation of protective corrosion products in the composite layer supported by SiO2. 相似文献
998.
Selective seeding for growing diamond on Si substrates was performed by conventional lithography using photoresist mixed with fine diamond particles. The selectivity was improved by filtering the diamond powder-photoresist mixture and carrying out reactive ion etching of patterned substrates. As a result, a selectivity up to 2.0 × 102 or higher was achieved. The resolution was of the order of 1 μm. Field emission from diamonds prepared using this selective growth method was observed without any postgrowth treatment. The measured current vs. voltage plot of a diode showed a rectifying characteristic. Under a forward bias, a current of about 15 μA was obtained at about 570 V, with a turn-on voltage of about 480 V. The emission current was comparable with that which had been observed for Si field emitter tips. 相似文献
999.
Carbon oxidation with platinum supported catalysts 总被引:3,自引:0,他引:3
Junko Oi Uchisawa Akira Obuchi Zhen Zhao Satoshi Kushiyama 《Applied catalysis. B, Environmental》1998,18(3-4):L183-L187
The effect of the support oxide, Pt precursor and reactant gas composition on the catalysis of soot oxidation was investigated using carbon black as a model soot and simulated exhaust gases. The Pt precursors used were Pt(NH3)4(OH)2, H2PtCl6·6H2O, Pt(NH3)4(NO3)2, and Pt(NH3)4Cl2. The support metal oxides used were SiO2, Al2O3, and ZrO2. Pt/SiO2 prepared from Pt(NH3)4(OH)2 showed the highest carbon oxidation activity. It had much higher activity in the condition of N2+O2+H2O+NO+SO2 than without NO and SO2. 相似文献
1000.
Observation of magnetic domains with in-plane magnetisations is demonstrated by scanning near-field optical microscopy (SNOM) in reflection mode. The longitudinal and transverse magneto-optical Kerr effects are employed as the contrast mechanisms; these are observed as either a change in the polarisation of the reflected light or reflectance, depending on magnetisation direction. SNOM images of Co and Ni thin films show magneto-optical contrast depending on polarisation of the incident and detected light. For the smooth cobalt thin films, the orientation for magnetic domains is estimated, based on the correlation between the contrasts in SNOM images obtained in different polarisation configurations and the directions of the magnetic vectors of the incident and reflected light. For the nickel films with pronounced topographic structures, the resulting near-field polarisation dependencies are more complicated, suggesting that the magneto-optical contrast in SNOM images are affected by the topographic cross-talk due to the depolarisation effects on surface topographic features. 相似文献