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Recovery of free volume in PIM-1 membranes through alcohol vapor treatment

Faiz Almansour, Monica Alberto, Rupesh S. Bhavsar, Xiaolei Fan, Peter M. Budd, Patricia Gorgojo

《化学科学与工程前沿(英文)》 2021年 第15卷 第4期   页码 872-881 doi: 10.1007/s11705-020-2001-2

摘要: Physical aging is currently a major obstacle for the commercialization of PIM-1 membranes for gas separation applications. A well-known approach to reversing physical aging effects of PIM-1 membranes at laboratory scale is soaking them in lower alcohols, such as methanol and ethanol. However, this procedure does not seem applicable at industrial level, and other strategies must be investigated. In this work, a regeneration method with alcohol vapors (ethanol or methanol) was developed to recover permeability of aged PIM-1 membranes, in comparison with the conventional soaking-in-liquid approach. The gas permeability and separation performance, before and post the regeneration methods, were assessed using a binary mixture of CO and CH (1:1, v:v). Our results show that an 8-hour methanol vapor treatment was sufficient to recover the original gas permeability, reaching a CO permeability>7000 barrer.

关键词: polymer of intrinsic microporosity (PIM)     PIM-1     physical aging     gas separation     vapor-phase regeneration    

无源互调测量——挑战与解决方案 Review

蔡张华, 刘列, Francesco de Paulis, 漆一宏

《工程(英文)》 2022年 第14卷 第7期   页码 181-191 doi: 10.1016/j.eng.2022.02.012

摘要: 当部件的其他射频(RF)性能设计良好时,无源互调(PIM)干扰可能成为限制系统SNR的重要因素。无论是基站、室内分布式天线系统还是卫星系统,都存在严格的PIM级别要求,以最大程度地减少干扰并增强多载波网络中的网络容量。尤其是5G无线通信等大功率、大带宽的系统,PIM干扰更严重。本文介绍了国际电工委员会(IEC)等标准组织推荐的当前主要PIM 测量方法,以及PIM 测量中的几个关键挑战及其解决方案(包括PIM 测试仪的设计、
PIM源的定位、紧凑型PIM暗室的设计,以及PIM暗室的评估方法)。这些挑战对于解决实际无线通信系统中设备可能出现的PIM问题具有重要意义。

关键词: 无源互调 (PIM)     PIM源定位     消声室    

Combination of biomaterial transplantation and genetic enhancement of intrinsic growth capacities to

Bin Yu, Xiaosong Gu

《医学前沿(英文)》 2019年 第13卷 第2期   页码 131-137 doi: 10.1007/s11684-018-0642-z

摘要: The inhibitory environment that surrounds the lesion site and the lack of intrinsic regenerative capacity of the adult mammalian central nervous system (CNS) impede the regrowth of injured axons and thereby the reestablishment of neural circuits required for functional recovery after spinal cord injuries (SCI). To circumvent these barriers, biomaterial scaffolds are applied to bridge the lesion gaps for the regrowing axons to follow, and, often by combining stem cell transplantation, to enable the local environment in the growth-supportive direction. Manipulations, such as the modulation of PTEN/mTOR pathways, can also enhance intrinsic CNS axon regrowth after injury. Given the complex pathophysiology of SCI, combining biomaterial scaffolds and genetic manipulation may provide synergistic effects and promote maximal axonal regrowth. Future directions will primarily focus on the translatability of these approaches and promote therapeutic avenues toward the functional rehabilitation of patients with SCIs.

关键词: spinal cord injury     biomaterial     extrinsic barrier     intrinsic regeneration capacity    

IP组播路由协议的研究与实现

李炜

《中国工程科学》 2002年 第4卷 第1期   页码 82-88

摘要: 分析了协议独立的组播路由一稀疏模式(PIM-SM)的缺陷,提出多个会聚 点(RPs)的PIM-SM的改进机制。多个RPs机制有效地提高了原有单个RP的PIM-SM协议的健壮性,有利 于实现负载均衡、分类业务及提高系统的容错性能,并讨论多个RPs机制的开销问题。分析了 PIM-SM实现细 节和组播技术的前景。

关键词: 协议独立的组播路由一稀疏模式(PIM-SM)     多会聚点(RPs)     组播    

Organic conjugated polymers and polymer dots as photocatalysts for hydrogen production

《能源前沿(英文)》 2021年 第15卷 第1期   页码 667-677 doi: 10.1007/s11708-021-0767-7

摘要: Owing to the outstanding characteristics of tailorable electronic and optical properties, semiconducting polymers have attracted considerable attention in recent years. Among them, organic polymer dots process large breadth of potential synthetic diversity are the representative of photocatalysts for hydrogen production, which presents both an opportunity and a challenge. In this mini-review, first, the organic polymer photocatalysts were introduced. Then, recent reports on polymer dots which showed a superior photocatalytic activity and a robust stability under visible-light irradiation, for hydrogen production were summarized. Finally, challenges and outlook on using organic polymer dots-based photocatalysts from hydrogen production were discussed.

关键词: polymer dots (Pdots)     photocatalysis     hydrogen production    

Construction of interfacial dynamic bonds for high performance lignin/polymer biocomposites

《化学科学与工程前沿(英文)》 2023年 第17卷 第10期   页码 1372-1388 doi: 10.1007/s11705-023-2302-3

摘要: Lignin is the largest natural aromatic biopolymer, but usually treated as industrial biomass waste. The development of lignin/polymer biocomposites can promote the high value utilization of lignin and the greening of polymers. However, the weak interfacial interaction between industrial lignin and polymer induces poor compatibility and serious agglomeration in polymer owing to the strong intermolecular force of lignin. As such, it is extremely difficult to prepare high performance lignin/polymer biocomposites. Recently, we proposed the strategy of in situ construction of interfacial dynamic bonds in lignin/polymer composites. By taking advantage of the abundant oxygen-containing polar groups of lignin, we inserted dynamic bonding connection such as hydrogen bonds and coordination bonds into the interphase between lignin and the polymer matrix to improve the interfacial interactions. Meanwhile, the natural amphiphilic structure characteristics of lignin were utilized to construct the hierarchical nanophase separation structure in lignin/polymer composites. The persistent problems of poor dispersity and interfacial compatibility of lignin in the polymer matrix were effectively solved. The lignin-modified polymer composites achieved simultaneously enhanced strength and toughness. This concise review systematically summarized the recent research progress of our group toward building high-performance lignin/polymer biocomposites through the design of interfacial dynamic bonds (hydrogen bonds, coordination bonds, and dynamic covalent bonds) between lignin and different polymer systems (polar plastics, rubber, polyurethane, hydrogels, and other polymers). Finally, the future development direction, main challenges, and potential solutions of lignin application in polymers were presented.

关键词: lignin     polymer     interfacial dynamic bonds    

Effect of polymer structures on electro-optical properties of polymer stabilized liquid crystal films

WANG Shoulian, HE Jie, ZENG Yu, YAN Bin, WANG Yinghan

《化学科学与工程前沿(英文)》 2008年 第2卷 第3期   页码 265-268 doi: 10.1007/s11705-008-0054-8

摘要: The polymer stabilized liquid crystal (PSLC) film is a relatively novel electro-optical material, which is generally obtained by dissolving a small amount of a bifunctional photoreactive monomer in a low molecular mass liquid crystal. In this paper, the PSLC films were prepared with photoreactive biphenyl methacrylate monomers by photopolymerization induced phase separation. The effects of liquid crystal concentration, curing time, monomer structures and alignment layer on the electro-optical properties of PSLC films were investigated. The results show that the transmittance in the OFF state () increased with the liquid crystal concentration, but the driving voltage decreased. was also influenced by the curing time. Furthermore, when polyimide was used as alignment layer, the films prepared from the bifunctional monomer shows a higher T, while those from the single functional monomer exhibited a deformed electro-optical curve due to the unsteady polymer networks.

Deformation analysis of shape memory polymer for morphing wing skin under airflow

Weilong YIN, Jingcang LIU, Jinsong LENG,

《机械工程前沿(英文)》 2009年 第4卷 第4期   页码 447-449 doi: 10.1007/s11465-009-0062-5

摘要: The method for analyzing the out-of-plane deformation of a flexible skin under airflow is developed in this paper. The aerodynamic analysis is performed using the CFD software, and the structural analysis is performed using finite element method. The chief aim of the present study is to investigate the out-of-plane deformation of the shape memory polymer (SMP) skin at different temperatures. Numerical results show that the maximum out-of-plane displacement of the SMP skin increases with increasing temperature. When the SMP skin is heated to 53°C, the maximum out-of-plane displacement is about 7 mm. It decreases by 72%, when the SMP skin is applied with a uniform pre-strain of 0.1.

关键词: aircraft     morphing     skin     shape memory polymer (SMP)     deformation     pre-strain    

Fracture model for the prediction of the electrical percolation threshold in CNTs/Polymer composites

Yang SHEN, Pengfei HE, Xiaoying ZHUANG

《结构与土木工程前沿(英文)》 2018年 第12卷 第1期   页码 125-136 doi: 10.1007/s11709-017-0396-8

摘要: In this paper, we propose a 3D stochastic model to predict the percolation threshold and the effective electric conductivity of CNTs/Polymer composites. We consider the tunneling effect in our model so that the unrealistic interpenetration can be avoided in the identification of the conductive paths between the CNTs inside the polymer. The results are shown to be in good agreement with reported experimental data.

关键词: electrical percolation     CNTs/Polymer composites     fracture model     electric conductivity     tunnelling effects    

Experimental investigation on freeze−thaw durability of polymer concrete

《结构与土木工程前沿(英文)》 2021年 第15卷 第4期   页码 1038-1046 doi: 10.1007/s11709-021-0748-2

摘要: Assessing the durability of concrete is of prime importance to provide an adequate service life and reduce the repairing cost of structures. Freeze–thaw is one such test that indicates the ability of concrete to last a long time without a significant loss in its performance. In this study, the freeze–thaw resistance of polymer concrete containing different polymer contents was explored and compared to various conventional cement concretes. Concretes’ fresh and hardened properties were assessed for their workability, air content, and compressive strength. The mass loss, length change, dynamic modulus of elasticity, and residual compressive strength were determined for all types of concretes subjected to freeze–thaw cycles according to ASTM C666-procedure A. Results showed that polymer concrete (PC) specimens prepared with higher dosages of polymer contents possessed better freeze–thaw durability compared to other specimens. This high durability performance of PCs is mainly due to their impermeable microstructures, absence of water in their structure, and the high bond strength between aggregates and a polymer binder. It is also indicated that the performance of high-strength concrete containing air-entraining admixture is comparable with PC having optimum polymer content in terms of residual compressive strength, dynamic modulus of elasticity, mass loss, and length change.

关键词: durability test     freeze-thaw resistance     polymer concrete     residual compressive strength     ASTM C666-15    

炼化企业设备的本质安全可靠与监管智能化对策研究

王庆锋,刘家赫,柳建军,王学斌,李中

《中国工程科学》 2019年 第21卷 第6期   页码 129-136 doi: 10.15302/J-SSCAE-2019.10.002

摘要:

国内炼化企业设备事故频发,设备本质安全可靠运行面临众多挑战,其中设备可靠性设计 /制造、风险管理、监测控制智能化是工程迫切需求。为提升炼化企业设备的本质安全可靠与监管智能化水平,本文揭示了设备本质安全可靠与监管智能化内涵,阐述了可靠性设计 /制造、风险管理、监测控制智能化技术发展趋势,提出了设备本质安全可靠与监管智能化的对策、措施和建议。完成了某催化装置的主风机本质安全可靠与监管智能化改造案例研究,结果表明设备本质安全可靠与监管智能化改造对设备安全运行具有重要工程意义。

关键词: 本质安全     可靠性设计     可靠性制造     风险管理     监管智能化    

Tribological study on the surface modification of metal-on-polymer bioimplants

《机械工程前沿(英文)》 2022年 第17卷 第2期 doi: 10.1007/s11465-022-0682-6

摘要: The tribological performance of artificial joints is regarded as the main factor of the lifespan of implanted prostheses. The relationship between surface roughness and coefficient of friction (COF) under dry and lubricated conditions is studied. Results show that under dry test, friction coefficient is not reduced all the time with a decrease in surface roughness. On the contrary, a threshold of roughness value is observed, and frictional force increases again below this value. This critical value lies between 40 and 100 nm in Sa (roughness). This phenomenon is due to the transfer of friction mechanisms from abrasion to adhesion. Under wet test, COF always decreases with reduction in surface roughness. This result is mainly attributed to the existence of a thin layer of lubricant film that prevents the intimate contact of two articulating surfaces, thus greatly alleviating adhesion friction. Furthermore, surface texturing technology is successful in improving the corresponding tribological performance by decreasing friction force and mitigating surface deterioration. The even-distribution mode of texturing patterns is most suitable for artificial joints. By obtaining the optimal surface roughness and applying texturing technology, the tribological performance of polymer-based bioimplants can be greatly enhanced.

关键词: artificial joints     surface roughness     friction     surface texturing    

Hyperbranched magnetic polymer: highly efficient removal of Cr(VI) and application in electroplating

《化学科学与工程前沿(英文)》 2023年 第17卷 第10期   页码 1568-1580 doi: 10.1007/s11705-023-2303-2

摘要: By using a two-step hydrothermal method and trithiocyanuric acid (TTCA), 2,4,6-trihydrazino-1,3,5-triazine (THT), and Fe3O4 as raw materials, a spherical magnetic adsorbent polymer (TTCA/THT@Fe3O4) was synthesized to achieve the efficient removal of Cr(VI) from wastewater. Under optimal adsorption conditions, the maximum adsorption capacity of TTCA/THT@Fe3O4 for Cr(VI) can reach 1340 mg∙g‒1. Notably, the removal efficiency can approach 98.9%, even at the lower concentration of 20 mg∙L‒1 Cr(VI). For actual wastewater containing Cr(VI), the Cr(VI) concentration was reduced from 25.8 to 0.4 mg∙L‒1, a remarkable 20% lower than the current industry discharge standard value. A mechanism for the high adsorption performance of Cr(VI) on TTCA/THT@Fe3O4 was investigated using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and density functional theory. It can be plausibly attributed to the formation of Cr/N and Cr/S coordination bonds. Additionally, surface electrostatic adsorption, reduction effects, and the spherical polymer structure increase the contact area with Cr(VI), maximizing adsorption. The synergistic effect of adsorption and reduction enhances the adsorption performance of TTCA/THT@Fe3O4 for Cr(VI) and total chromium in water. The resultant polymer has a simple preparation process, excellent adsorption performance, easy magnetic separation, and promising application for actual wastewater.

关键词: magnetic polymer     chromium removal     hydrogen bonding     recyclability     actual wastewater    

Selective sorption of perfluorooctane sulfonate on molecularly imprinted polymer adsorbents

Shubo DENG, Danmeng SHUAI, Qiang YU, Jun HUANG, Gang YU

《环境科学与工程前沿(英文)》 2009年 第3卷 第2期   页码 171-177 doi: 10.1007/s11783-009-0017-4

摘要: Perfluorooctane sulfonate (PFOS), as a potential persistent organic pollutant, has been widely detected in water environments, and has become a great concern in recent years. PFOS is very stable and difficult to decompose using conventional techniques. Sorption may be an attractive method to remove it from water. In this study, the molecularly imprinted polymer (MIP) adsorbents were prepared through the polymerization of 4-vinylpyridine under different preparation conditions in order to remove perfluorooctane sulfonate (PFOS) from water. The MIP adsorbents using perfluorooctanoic acid (PFOA) as the template had good imprinting effects and could selectively remove PFOS from aqueous solution. The sorption behaviors including sorption kinetics, isotherms, and effect of pH, salt, and competitive anions were investigated. Experimental results showed that the sorption of PFOS on the MIP adsorbents was very fast, pH-dependent, and highly selective. The achieved fast sorption equilibrium within 1 h was attributed to the surface sorption on the fine adsorbents. The sorption isotherms showed that the sorption selectivity of PFOS on the MIP adsorbents decreased at high PFOS concentrations, which may be due to the double-layer sorption and the formation of PFOS micelles on the sorbent surface. The sorption of PFOS on the MIP adsorbents was mainly dominated by the electrostatic interaction between the protonated vinylpyridine on the adsorbent surface and the anionic PFOS. The prepared MIP adsorbents can potentially be applied in water and wastewater treatment for selective removal of PFOS.

关键词: perfluorooctane sulfonate (PFOS)     molecularly imprinted polymer (MIP) adsorbents     selective sorption     electrostatic interaction    

Intrinsic kinetics and external diffusion of catalytic steam gasification of fine coal char particles

Xuantao Wu, Jie Wang

《化学科学与工程前沿(英文)》 2019年 第13卷 第2期   页码 415-426 doi: 10.1007/s11705-018-1725-8

摘要: Catalytic steam gasification of fine coal char particles was carried out using a self-made laboratory reactor to determine the intrinsic kinetics and external diffusion under varying pressures (0.1–0.5 MPa) and superficial gas flow velocities (GFVs) of 13.8–68.8 cm?s . In order to estimate the gas release rate at a low GFV, the transported effect of effluent gas on the temporal gasification rate pattern was simulated by the Fluent computation and verified experimentally. The external mass transfer coefficients ( ) and the effectiveness factors were determined at lower GFVs, based on the intrinsic gasification rate obtained at a high GFV of 55.0 cm?s . The was found to be almost invariable in a wider carbon conversion of 0.2–0.7. The variations of at a median carbon conversion with GFV, temperature and pressure were found to follow a modified Chilton-Colburn correlation: (0.04< <0.19), where is total pressure and is atmospheric pressure. An intrinsic kinetics/external diffusion integrating model could well describe the gasification rate as a function of GFV, temperature and pressure over a whole gasification process.

关键词: coal char     catalytic steam gasification     pressure     kinetics     diffusion    

标题 作者 时间 类型 操作

Recovery of free volume in PIM-1 membranes through alcohol vapor treatment

Faiz Almansour, Monica Alberto, Rupesh S. Bhavsar, Xiaolei Fan, Peter M. Budd, Patricia Gorgojo

期刊论文

无源互调测量——挑战与解决方案

蔡张华, 刘列, Francesco de Paulis, 漆一宏

期刊论文

Combination of biomaterial transplantation and genetic enhancement of intrinsic growth capacities to

Bin Yu, Xiaosong Gu

期刊论文

IP组播路由协议的研究与实现

李炜

期刊论文

Organic conjugated polymers and polymer dots as photocatalysts for hydrogen production

期刊论文

Construction of interfacial dynamic bonds for high performance lignin/polymer biocomposites

期刊论文

Effect of polymer structures on electro-optical properties of polymer stabilized liquid crystal films

WANG Shoulian, HE Jie, ZENG Yu, YAN Bin, WANG Yinghan

期刊论文

Deformation analysis of shape memory polymer for morphing wing skin under airflow

Weilong YIN, Jingcang LIU, Jinsong LENG,

期刊论文

Fracture model for the prediction of the electrical percolation threshold in CNTs/Polymer composites

Yang SHEN, Pengfei HE, Xiaoying ZHUANG

期刊论文

Experimental investigation on freeze−thaw durability of polymer concrete

期刊论文

炼化企业设备的本质安全可靠与监管智能化对策研究

王庆锋,刘家赫,柳建军,王学斌,李中

期刊论文

Tribological study on the surface modification of metal-on-polymer bioimplants

期刊论文

Hyperbranched magnetic polymer: highly efficient removal of Cr(VI) and application in electroplating

期刊论文

Selective sorption of perfluorooctane sulfonate on molecularly imprinted polymer adsorbents

Shubo DENG, Danmeng SHUAI, Qiang YU, Jun HUANG, Gang YU

期刊论文

Intrinsic kinetics and external diffusion of catalytic steam gasification of fine coal char particles

Xuantao Wu, Jie Wang

期刊论文