Self-expandable hydrogel biliary stent design utilizing the swelling property of poly(vinyl alcohol) hydrogel

We have developed a novel self-expandable biliary stent comprising poly(vinyl alcohol) (PVA). The swelling ratio of the dried PVA hydrogels decreased from 6.7 to 2.6 as the saponification degree increased from 95 to 99.9, whereas the storage modulus and tear strength increased from 17 to 400 kPa and from 0.5 to 10 N mm⁻¹, respectively. The dimensional ratios of the inner- and outer-diameter and the length of the dried tube-shaped hydrogels (saponification degree of 98.5) prepared by simple air drying isotropically increased 1.4–1.5 times in physiological saline. Meanwhile, the dimensional ratios of the dried hydrogels prepared by drying under extension increased by twice, whereas the length decreased slightly, indicating anisotropic swelling. The radial force of the reswollen tube-shaped hydrogels (6.6 ± 0.6 mN mm⁻²) was significantly higher than that of a conventional metallic stent (4.4 ± 0.3 mN mm⁻²), suggesting that PVA hydrogels were applicable as self-expandable stents. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48851.     

Selective production of hydrogen by partial oxidation of methanol over catalysts derived from CuZnAl‐layered double hydroxides

Hydrogen production by partial oxidation of methanol (POM) reaction (CH₃OH + (1/2)O₂ ⇌ ₂H₂ + CO₂) was investigated over a series of CuZnAl ternary oxide catalysts derived from CuZnAl hydroxycarbonate precursors containing hydrotalcite‐like layered double hydroxide as a major phase. These catalysts exhibited a good catalytic activity and high H₂ selectivity. A methanol conversion of about 40–60% was obtained at 200°C with high selectivity of H₂ and CO₂. The undesirable by‐product, CO was virtually not produced over most of the catalysts at this temperature. The catalytic activity was found to decrease with increasing (Cu + Zn)/Al atomic ratio in the precursor and, was correlated with Cu metal surface areas, Cu dispersion and Cu particle sizes, which were calculated by both XRD and TPR‐N₂O passivation methods. The catalyst with higher Cu surface areas and Cu dispersion displayed a higher catalytic activity. Lifetime experiments showed that these catalysts were stable over a period of 24 h of continuous operation. Catalyst precursors containing hydroxycarbonates other than LDH as a major phase offered considerable amount of dimethyl ether as a by‐product. This revised version was published online in July 2006 with corrections to the Cover Date.     

一种CDMA接收机在单频点阻塞干扰环境中的性能分析

本文考虑同步码分多址通信系统在单频点阻塞干扰环境中,一种抗多址干扰单用户检测接收机(I.Acax等人1994年提出)的误码率特性.结果表明,这种接收机(A-T接收机)在系统用户数很大时仍具有良好的抗单频点阻塞干扰性能。     

Effects of miscibility on probe tack of natural-rubber-based pressure-sensitive adhesives

Natural rubber (NR) was blended in various ratios with 29 kinds of tackifier resins, which were prepared from rosin, terpenes, and petroleum. Miscibilities of all the blend systems were illustrated as phase diagrams in our previous articles. From these blend systems, we selected 7 systems having typical phase diagrams [completely miscible, completely immiscible, and lower critical solution temperature (LCST) types] and carried out measurements of probe tack. Probe tack values were measured at various rates of separation and temperatures to obtain master curves. In the case of miscible pressure sensitive adhesives (PSAs) at the condition of measurement, the peak position in the master curve of probe tack shifted to the lower velocity (higher temperature) as the tackifier content increased. On the contrary, immiscible PSAs had much smaller probe tack values than miscible ones and did not give manifest shift of peaks. © 1998 John Wiley & Sons, Inc. J. Appl. Polym. Sci. 70: 771–776, 1998     

角蛋白基吸附剂的研究进展

角蛋白在羊毛、人的头发和鸟的羽毛中大量存在,是一种潜在有用的可再生生物聚合物。在角蛋白的主链和侧链上含有多种官能团,可通过物理或化学吸附机制分离有毒有害物质,是制备生物质基吸附剂的理想材料。本文详细综述了角蛋白基吸附剂的制备方法、原理及在废水处理中的应用,揭示了其吸附机理,最后指出了角蛋白基吸附剂的制备、吸附和再生过程中存在的问题及今后的发展方向。     

In-situ observation of structural change in MWCNTs under high-pressure H2 gas atmosphere

Multi-walled carbon nanotubes having a tube-opened framework (o-MWCNTs) have been pressurized in an atmosphere of hydrogen up to 2.5 GPa and at room temperature using a diamond-anvil cell (DAC). Compression up to 0.57 GPa was accompanied by expansion of the honeycom-lattice structure of graphene sheets in spite of decreasing interlayer distance. A deviation in the in-plane C–C distance was obtained to be 3.8 × 10^− 4 nm at 0.57 GPa. The expansion in the honeycom-lattice structure suggests generation of charge-transfer interaction between graphite and hydrogen. This is one of the proofs that hydrogen is intercalated in the interlayer space of o-MWCNTs.     

Development of high performance,waterborne coatings. Part I: Emulsification of epoxy resin

A new manufacturing process of high performance, waterborne coatings for can coating applications is developed, which includes emulsification of an epoxy resin with or without its hardener by incorporation of an acrylic resin. It becomes possible by this new process to emulsify a variety of resins with minimum effects of the surfactant acrylic resin. Thus, latitude to design formulations is widened and the performance of epoxy resin and its hardener can be fully developed.     

关于CMA盲均衡算法的稳态剩余误差的研究

CMA是一种广泛应用的盲均衡算法，但由于分析的困难，人们对它的了解还不充分。本文研究了CMA收敛后的剩余误差问题，发现CMA的超量均方误差与信号的统计特性有关，这一发现揭示了CMA本质特性的一个方面，有助于加深对CMA的认识；另外本文还给出了一个能大致反映超量均方误差与信号关系的特征值，对工程应用和理论分析有一定的帮助。     

Insulation properties of a CO2/N2 50% SF6 gas mixture in a nonuniform field

This paper describes partial discharge (PD) inception and breakdown voltage characteristics of a CO₂/N₂/SF₆ gas mixture in a nonuniform field. These voltage characteristics were investigated with ac high voltage by changing the mixture rate of each gas of CO₂, N₂, and SF₆ gas and the gas pressure from 0.1 MPa to 0.6 MPa. It was found that adding a small amount of CO₂ gas into a N₂/SF₆ mixture causes a drastic increase in the breakdown voltage. For instance, when the mixture rate of SF₆ in N₂/SF₆ gas mixture is 50%, with the addition of 1% CO₂ the maximum breakdown voltage becomes 1.31 and 1.15 times higher than that of a 50% N₂/50% SF₆ gas mixture and pure SF₆ gas, respectively. Moreover, those voltage characteristics of a CO₂/N₂/SF₆ gas mixture were also investigated by changing the electric field utilization factor as well as by applying positive and negative standard lightning impulse voltages in order to discuss the corona stabilization effect, which seems to be one reason for the drastic increase in the breakdown voltage. These results and breakdown mechanism of the CO₂/N₂/SF₆ gas mixture are discussed on the basis of the corona stabilization effect and the dissociation energies of the component gases by observing PD light images, PD light intensities through a blue and red filter, and PD current waveforms. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 140(3): 34–43, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10019