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991.
Chinnasamy Gandhimathi Subramanian Sundarrajan Takeshi Matsuura Dinesh Kumar Srinivasan He Wei Dong Xuecheng Seeram Ramakrishna 《应用聚合物科学杂志》2021,138(17):50296
Electrospun nanofiber membranes (ENM) made of polymers such as polysulfone and poly(vinylidene fluoride) (PVDF) have a much higher contact angle (CA) and also more hydrophobic when compared to the virgin polymers. For water treatment applications, membranes with hydrophilic nature are highly desirable in order to achieve high flux and less fouling potentials. Hence, in the present study, highly hydrophilic electrospun nanofiber membranes (ENMs) were prepared by blending PVDF polymer with amphiphilic polyethylene-block-poly (ethylene glycol) (PE-b-PEG) copolymer. Resulting amphiphilic ENMs were highly porous (77%–92%) and the breaking elongation of 140% with a young's modulus of 2.55 MPa was observed. When compared with the control PVDF membrane, PE-b-PEG blended ENMs revealed higher water permeation flux owing to the enrichment of the hydrophilic PEG segments at the membrane surface, which was confirmed by using X-ray photoelectric spectroscopy and Energy-dispersive spectroscopy measurements. When compared to the phase inversion process (CA of 97.3°) blended ENM had CA of 0°, which indicates that besides hydrophilic block copolymer segments, the nature of membrane formation also contributes its role in influencing the hydrophilicity of the membrane. This improved hydrophilicity in combination with larger pore sizes of the PVDF/ PE-b-PEG membranes have contributed to enhancement of pure water flux, protein solution permeability and water flux recovery, which can be applied potentially for water treatment applications. 相似文献
992.
993.
概述了汽车用薄钢板和硅钢片的现状与未来展望。指出对于薄钢板,应该尽量降低因提高强度而导致的成形性的恶化,同时论述了获得有利于车体轻量化的现代高强度钢所适宜的显微组织及其制备的物理冶金方法。讨论了混合型汽车电机铁芯要求的电磁性能,认为降低高频区的铁损非常重要,并可以通过钢的纯净化和织构的适宜控制得以实现。 相似文献
994.
This paper describes a new approach to restoring scanned color document images where the backside image shows through the paper sheet. A new framework is presented for correcting show-through components using digital image processing techniques. First, the foreground components on the front side are separated from the background and backside components through locally adaptive binarization for each color component and edge magnitude thresholding. Background colors are estimated locally through color thresholding to generate a restored image, and then corrected adaptively through multi-scale analysis along with comparison of edge distributions between the original and the restored image. The proposed method does not require specific input devices or the backside to be input; it is able to correct unneeded image components through analysis of the front side image alone. Experimental results are given to verify effectiveness of the proposed method. 相似文献
995.
To obtain a fundamental understanding of the corrosion behavior of lead-free solder, the corrosion behavior of tin-based eutectic alloys in sulfuric and nitric acids saturated with oxygen was investigated. The presence of bismuth in a Sn-Bi alloy (43Sn-57Bi (wt.%)) slightly accelerated the preferential dissolution of tin instead of dissolving itself in 0.05 M H2SO4 and greatly accelerated, in 0.1 M HNO3 compared with that of pure tin. In both acids, dissolution of both tin and zinc from a Sn-Zn alloy (91Sn-9Zn (wt.%)) occurred depending on the ratio of composition, and dissolution of tin from a Sn-Ag alloy (96.5Sn-3.5Ag (wt.%)) was accelerated. Dipping tests in H2SO4 and HNO3 of pH 4 showed that dissolution of only zinc and lead occurred, suggesting that the tin-based alloys investigated in this study are preferable to substitutes for lead solders in terms of corrosion resistance. 相似文献
996.
A. Ohno 《JOM Journal of the Minerals, Metals and Materials Society》1986,38(1):14-16
To prevent the nucleation of crystals on the mold wall in the continuous casting of metals, a heated mold that maintained that temperature above the solidification temperature of the cast metal was used instead of the conventional cold mold. The cooling of the ingot was conducted outside of the mold. Heat was conducted axially along the ingot from the mold zone to the cooling zone. The principle of the O.C.C. (Ohno Continuous Casting) Process® was applied to the horizontal casting and vertical (upward) casting of wire and platelike ingots of Sn and Al. The ingots consisted of a completely unidirectionally solidified structure. It was possible to obtain a long single crystal ingot as a result of the growth competition of crystals. 相似文献
997.
Hiroshi Kimura Takeshi Ohura Makoto Takeishi Shigeo Nakamura Yoshiharu Doi 《Polymer International》1999,48(11):1073-1079
The effective microbial production of copolyesters of 3‐hydroxybutyrate (3HB) and 4‐hydroxybutyrate (4HB) with high mole fractions of 4HB units by a wild‐type strain of Ralstonia eutropha H16 was investigated in culture solutions containing 4‐hydroxybutyric acid (4HBA) and various carbon substrates in the presence of a nitrogen source such as ammonium sulfate. The addition of glucose or acetic acid to the culture solution containing 4HBA in the presence of ammonium sulfate resulted in the production of random copolymers of P(3HB‐co‐4HB) with compositions of up to 82 mol% 4HB, but the yield of copolymers was less than 7 wt% of dried cell weights. In contrast, when n‐alkanoic acids such as propionic acid, butyric acid, valeric acid and hexanoic acid, being subject to β‐oxidation metabolism in the cell, were used as the co‐substrates of 4HBA in the presence of ammonium sulfate, a mixture of copolymers with two different 4HB compositions was produced, and copolyesters with compositions of 93–100 mol% 4HB were isolated from chloroform–n‐hexane insoluble fractions in the mixture of copolymers. Especially, when this wild‐type Ralstonia eutropha H16 was cultivated in a medium containing 4HBA (15 g litre−1), propionic acid (5 g litre−1) and ammonium sulfate (5 g litre−1), namely C/N (mol/mol) = 10, the P(4HB) homopolymer was produced at maximally 34 wt% of dry cell weight (7.8 g litre−1), and the conversion yield of 4HBA to P(4HB) homopolymer resulted in values as high as 21 mol%. © 1999 Society of Chemical Industry 相似文献
998.
A new type of epoxy resin containing anthracene moiety in the backbone was synthesized and was confirmed by elemental analysis, infrared spectroscopy, and 1H nuclear magnetic resonance spectroscopy. Thermal properties of its cured polymer with phenol novolac were examined by thermomechanical, dynamic mechanical, and thermogravimetric analyses. The cured polymer with phenol novolac showed higher glass transition temperature (Tg), lower thermal expansion, lower moisture absorption, and higher anaerobic char yield at 700°C than a cured polymer having a phenylene group in place of anthracene moiety. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 953–959, 1999 相似文献
999.
The storage modulus (E′) and loss modulus (E″) of Japanese lacquer films were measured over a temperature range of −150 to 400°C. Three relaxation processes labeled α, β, and γ were detected at 80, −60, and −140°C, and their apparent activation energies (ΔE) were 63–91, 13, and 9 kcal/mol, respectively. These were attributed to the micro-Brownian motions of polymerized urushiol, the molecular motion related to the absorbed water, and the motions of methylene groups in the side chains, respectively. With aging at room temperature, the location of the α peak shifted to higher temperature and its ΔE value decreased. This result was ascribed to the autoxidative polymerization of urushiol. The E′ of lacquer films increased with heat treatments at 100°C or above. When treated at temperatures below 200°C, the location of the α peak shifted to higher temperature, with a reduction in the ΔE value. Heat treatments at 200°C or above resulted in remarkable shrinkage and weight loss of films owing to the pyrolysis of lacquer constituents. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1727–1732, 1999 相似文献
1000.
Hiroshi KATANODA Takeshi MATSUOKA Seiji KURODA Jin KAWAKITA Hirotaka FUKANUMA Kazuyasu MATSUO 《热科学学报(英文版)》2005,14(2):126-129
To clarify the characteristics of gas flow in high velocity oxy-fuel (HVOF) thermal spray gun, aerodynamic research is performed using a special gun. The gun has rectangular cross-sectional area and sidewalls of optical glass to visualize the internal flow. The gun consists of a supersonic nozzle with the design Mach number of 2.0 followed by a straight passage called barrel. Compressed dry air up to 0.78 MPa is used as a process gas instead of combustion gas which is used in a commercial HVOF gun. The high-speed gas flows with shock waves in the gun and jets are visualized by schlieren technique. Complicated internal and external flow-fields containing various types of shock wave as well as expansion wave are visualized. 相似文献