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Development of electrorheological chip and conducting polymer-based sensor

Xianzhou ZHANG, Weihua LI, Weijia WEN, Yanzhe WU, Gordon WALLACE,

《机械工程前沿（英文）》 2009年第4卷第4期页码 393-396 doi: 10.1007/s11465-009-0043-8

摘要： This paper presents the development of an integrated sensor using two types of smart materials: electrorheological (ER) fluids and conducting polymers (CPs). The developed ER chip worked as an actuator, and it was driven by different voltages and control frequencies. When the four electrodes are controlled synchronously, the diaphragm acts as a vibrator whose frequency can be adjusted in accordance with the frequency of the electrical signals. The response signals of the CP sensor were recorded, and its properties were analyzed. Experimental results show that the amplitude decreases monotonically when the frequency increases, owing to the time delay in the pressure buildup in the ER chip. However, the displacement fluctuation of the diaphragm below 20Hz can be detected clearly even if the value is very low. When the vibration frequency is larger than 20Hz, the CP sensor can hardly detect the displacement fluctuation. Thus, the upper limit frequency that the CP sensor can detect is about 20Hz. The practical applications of this microdevice are also discussed.

关键词： electrorheological (ER) fluids conducting polymer (CP) polydimethylsioxane (PDMS) driving frequency amplitude bubble counter

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Development of an electrorheological chip and conducting polymer based sensor

Xianzhou ZHANG, Weihua LI, Weijia WEN, Yanzhe WU, Gordon WALLACE,

《机械工程前沿（英文）》 2009年第4卷第4期页码 472-472 doi: 10.1007/s11465-009-0077-y

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Fabrication and performance of PEN SOFCs with proton-conducting electrolyte

ZHONG Li, LUO Jingli, Karl Chuang

《化学科学与工程前沿（英文）》 2007年第1卷第1期页码 40-44 doi: 10.1007/s11705-007-0008-6

摘要： A positive-electrolyte-negative (PEN) assembly solid oxide fuel cell (SOFC) with a thin electrolyte film for intermediate temperature operation was fabricated. Instead of the traditional screen-printing method, both anode and cathode catalysts were pressed simultaneously and formed with the fabrication of nano-composite electrolyte by press method. This design offered some advantageous configurations that diminished ohmic resistance between electrolyte and electrodes. It also increased the proton-conducting rate and improved the performance of SOFC due to the reduction of membrane thickness and good contact between electrolyte and electrodes. The fabricated PEN cell generated electricity between 600?C and 680?C using HS as fuel feed and air as oxidant. Maximum power densities 40 mW " cm and 130 mW " cm for the PEN configuration with a Mo-Ni-S-based composite anode, nano-composite electrolyte (LiSO+AlO) film and a NiO-based composite cathode were achieved at 600?C and 680?C, respectively.

关键词： proton-conducting positive-electrolyte-negative temperature operation Mo-Ni-S-based composite advantageous

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Computer-Aided Design System for CP Single-Screw Compressor

SHEN Jing-feng, YAO Fu-sheng

《机械工程前沿（英文）》 2006年第1卷第1期页码 21-25 doi: 10.1007/s11465-005-0018-3

摘要：

To design various optimum parameters and simulate the working process of CP single-screw compressor, the Computer-Aided Design (CAD) system for the CP single-screw compressor has been established. A new method based on computer graphics technology, database technology, object-oriented programming technology, and visual simulation technology has been adopted in this CAD system. The system has integrated solid modeling function with parameterization design function and animator simulation function based on analyzing the working principle of the CP single-screw compressor. The experimental results show that the CAD system for the CP single-screw compressor is practical and feasible.

关键词： CP single-screw database technology simulation technology programming technology animator simulation

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Overcoming the challenges of conducting translational research in cell therapy

Sowmya Viswanathan, Armand Keating

《医学前沿（英文）》 2011年第5卷第4期页码 333-335 doi: 10.1007/s11684-011-0166-2

摘要： Cell therapy holds promise in addressing a number of unmet medical needs but despite its considerable impetus, faces numerous challenges including support for translational research in this area. Here, we examine the challenges confronting cell therapy research including the limited funding available for translational research partly due to the uncompetitive nature of required validation studies in cell therapy that of necessity are not hypothesis-driven. Other issues include lack of standardization of definitions of cell products, uncertainty regarding optimum preclinical animal models, duplication of efforts to secure regulatory approval and a lack of uniformity of nomenclature for some cell products. Nonetheless, several initiatives to address all of these issues are underway.

关键词： stem cells clinical trials funding animal models standardization common definitions

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Microfluidic dual loops reactor for conducting a multistep reaction

Si Hyung Jin, Jae-Hoon Jung, Seong-Geun Jeong, Jongmin Kim, Tae Jung Park, Chang-Soo Lee

《化学科学与工程前沿（英文）》 2018年第12卷第2期页码 239-246 doi: 10.1007/s11705-017-1680-9

摘要： Precise control of each individual reaction that constitutes a multistep reaction must be performed to obtain the desired reaction product efficiently. In this work, we present a microfluidic dual loops reactor that enables multistep reaction by integrating two identical loop reactors. Specifically, reactants A and B are synthesized in the first loop reactor and transferred to the second loop reactor to synthesize with reactant C to form the final product. These individual reactions have nano-liter volumes and are carried out in a stepwise manner in each reactor without any cross-contamination issue. To precisely control the mixing efficiency in each loop reactor, we investigate the operating pressure and the operating frequency on the mixing valves for rotary mixing. This microfluidic dual loops reactor is integrated with several valves to realize the fully automated unit operation of a multistep reaction, such as metering the reactants, rotary mixing, transportation, and collecting the product. For proof of concept, CdSeZn nanoparticles are successfully synthesized in a microfluidic dual loops reactor through a fully automated multistep reaction. Taking all of these features together, this microfluidic dual loops reactor is a general microfluidic screening platform that can synthesize various materials through a multistep reaction.

关键词： microfluidics multistep reaction rotary mixing nanoparticle

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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

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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

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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.

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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

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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

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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

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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 S_a (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

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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

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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