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排序方式: 共有84条查询结果,搜索用时 15 毫秒
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Medjahed Sidali Kheloufi Abdelkrim Bobocioiu Ema Kefaifi Aissa Kerkar Fouad Lebbou Kheirreddine 《SILICON》2022,14(1):87-97
Silicon - In this work the reverse flotation as beneficiation process for high-purity silica valorization from Draissa quartz deposits (Algeria) is studied as a potential raw material for... 相似文献
3.
Side‐chain polyesters were synthesized from N‐octyl‐, N‐dodecyl‐ or N‐hexadecyl‐diethanolamine and succinic acid anhydride. These polyesters were then transformed into polyester hydrochlorides by protonation of the amino groups using different amounts of HCl (20–100 mol%). Above 60 mol% the reaction is not quantitative and a degree of protonation of up to 88% is obtained. The structures of the synthesized polyesters and their hydrochlorides were determined by 1H nuclear magnetic resonance spectroscopy. The thermal properties of the synthesized polyesters and their hydrochlorides were also studied using differential scanning calorimetry in relation to the side‐chain length and the degree of polyester protonation. The polyester with octyl side chains and its hydrochlorides were amorphous liquids at room temperature, while the polyester and polyester hydrochlorides with hexadecyl side chains formed a smectic crystalline phase, SmB, or its tilted analogues. The polyester with a dodecyl side chain was also an amorphous liquid at room temperature, while its hydrochlorides with various degrees of protonation were smectic liquid crystals, as determined by X‐ray diffraction. By simply varying the degree of protonation the liquid crystal isotropization temperature was increased from 32 °C to 82 °C. Copyright © 2011 Society of Chemical Industry 相似文献
4.
Kronek J Kroneková Z Lustoň J Paulovičová E Paulovičová L Mendrek B 《Journal of materials science. Materials in medicine》2011,22(7):1725-1734
Poly(2-oxazolines) with varying alkyl chain lengths (e.g., methyl, ethyl, aryl) and molar masses have been tested for cell
cytotoxicity in vitro. A standard 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used for the
estimation of cell viability. Two monomers, 2-methyl-2-oxazoline and 2-ethyl-2-oxazoline, were found to provide polymers with
non-cytotoxic properties. The dependence of cell viability on molar mass confirmed the expected trend; the viability increased
with the higher molar mass of poly(2-ethyl-2-oxazoline) (PETOX), up to 15,000 g/mol. The results obtained for the polymers
with aliphatic side chains were compared with the analogues that possessed an aromatic moiety. All results confirmed low cytotoxicity
of the polymers prepared by cationic polymerization of 2-alkyl- and 2-aryl-2-oxazolines, which supports their utilization
in biomedical applications. Fluorescence microscopy and steady-state fluorescence were used to observe pyrene-labeled polymer
interactions with living cells. Polymer accumulated within the cells was found to be dependent on polymer concentration in
media. The immunoefficiency of aromatic and aliphatic oxazoline polymers and copolymers was also studied. Phagocytic and metabolic
activities of macrophages were used to assess the immunosuppressive effects of the selected copolymers for possible applications
in drug delivery and immunobiology. Overall, the tested polymers demonstrated no significant influences on the cellular immunological
parameters. 相似文献
5.
Kazuhiro Ema Hidemi Shigekawa Shin-ichi Hyodo 《Journal of the American Ceramic Society》1984,67(6):104-C
During strength measurements on plastic-coated optical glass fibers, the positions of fracture origins were determined by an acoustic technique. For samples other than those in which fracture was initiated at or very near the fixed ends, Weibull plots of the strength data exhibited a single-mode distribution with low variability (m=20 to 25, corresponding to a coefficient of variation of 6.6 to 10.6%). 相似文献
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A uniform Ni2Y layer was formed on a nickel substrate by electrolysis of yttrium ions in molten LiC-KCl-NaCl at 500°C, and the diffusion coefficient of yttrium in Ni2Y was found to be (2.84 ± 0.40) × 10–8 cm2s–1 using an electrochemical transient technique. 相似文献
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Atsuhiko Yamanaka Tooru Kitagawa Masayuki Tsutsumi Toshihiro Kashima Hiroyuki Fujishiro Kimiko Ema Yoshinobu Izumi Shigehiro Nishijima 《应用聚合物科学杂志》2004,93(6):2918-2925
High strength polyethylene fiber (Toyobo, Dyneema® fiber: hereinafter abbreviated to DF) has a negative thermal expansion coefficient. Relation between fiber structure and thermal strain of DF used as reinforcement of DF reinforced plastic (DFRP) for cryogenic use was investigated. The crystallinities and orientation angles of several kinds of polyethylene fibers having different modulus from 15 to 134Gpa (herein after abbreviated to DFs) were measured by NMR and X‐ray. We obtained the parameters of the mechanical series‐parallel model composed of crystal and amorphous by crystallinity and modulus. Thermal expansion coefficients of DFs were estimated by mechanical series‐parallel model. All DFs having different modulus showed negative thermal expansion coefficients in the temperature range from 180 to 300K, and absolute values of those markedly increased by increasing tensile modulus of DF. The estimated thermal expansion coefficients showed negative values, and thermal strains showed a similar curve to observed ones mostly. Average thermal expansion coefficients in the temperature range from 180 to 300K estimated by mechanical model agreed with the observed ones. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2918–2925, 2004 相似文献
10.
Noriaki Takagi Yoshinobu Izumi Kimiko Ema Tadashi Yamamoto Kazushige Nishizawa 《溶剂提取与离子交换》2013,31(6):1461-1471
ABSTRACT Dicyclohexano- 18-crown-6 (DC18C6), dissolved in chloroform, 1-octanol, toluene or cyclohexane, was irradiated by 60Co γ-rays. Radiolytic destruction of DC18C6, measured by gas chromatography, decreased in the order: chloroform > cyclohexane > 1-octanol > toluene. Distribution coefficients in the solvent extraction of strontium from nitric acid solution were measured. These distribution coefficients were minimally affected by γ-irradiation in toluene solution, but decreased with the absorbed dose in chloroform solution. It was suggested that the distribution coefficient for the liquid-liquid extraction system was influenced by radiolytic products. The effect of radiolytic products on the distribution coefficients was evaluated by considering DC18C6 remaining in the organic phase after irradiation. The distribution coefficient measured for the organic phase with radiolytic products was larger than that without radiolytic products. The radiolytic products were thus shown to contribute to the increase in the distribution coefficient. 相似文献