高浓度CO2在MEA溶液中平衡溶解度的实验研究

采用气液搅拌平衡装置,通过酸碱滴定和皂泡流量计测定了高浓度CO2在不同MEA溶液中的平衡溶解度。利用正交实验设计方法,考察了温度、CO2分压力、MEA质量浓度等因素对CO2平衡溶解度的影响。结果表明,在实验参数选定范围内,影响MEA中CO2平衡溶解度的因素主次顺序为：CO2分压力〉MEA质量浓度〉温度;MEA溶液中CO2的平衡溶解度随压力的增大而增大,随MEA质量浓度的增大而减小,随温度的增大而减小。     

Facile patterning of reduced graphene oxide film into microelectrode array for highly sensitive sensing

In this study, we develop a new technique to fabricate a reduced graphene oxide (rGO)-based microelectrode array (MEA) with low-cost soft lithography. To prepare patterned rGO, a polydimethylsiloxane (PDMS) mold with an array of microwells on its surface is fabricated using soft lithography, and GO is assembled on an indium tin oxide (ITO) electrode with a layer-by-layer method. The rGO pattern is formed by closely contacting the assembled GO film onto the ITO electrode with the PDMS mold filled with hydrazine solution in the microwells to selectively reduce the localized GO into the rGO. The MEA with patterned rGO as the microelectrode is characterized with Kelvin probe force microscopy (KFM), atomic force microscopy (AFM), and cyclic voltammetry (CV) with ferricyanide in aqueous solution as the redox probe. The KFM and AFM results demonstrate that each rGO pattern prepared under the present conditions is 3 μm in diameter, which is close to that of the PDMS mold we use. The CV results show that the rGO patterned onto the ITO exhibits a sigmoid-shaped voltammogram up to 200 mVs(-1) with a microampere level current response, suggesting that the rGO-based electrode fabricated with soft lithography behalves like a MEA. To demonstrate the potential electroanalytical application of the rGO-based MEA, prussian blue (PB) is electrodeposited onto the rGO-based MEA to form the PB/rGO-based MEA. Electrochemical studies on the formed PB/rGO-based MEA reveal that MEA shows a lower detection limit and a larger current density for the detection of H(2)O(2), as compared with the macroscopic rGO electrode. The method demonstrated here provides a simple and low-cost strategy for the fabrication of graphene-based MEA that are useful for electroanalytical applications.     

Achieving excellent strength-ductility synergy in twinned NiCoCr medium-entropy alloy via Al/Ta co-doping

Alloying is an effective strategy to tailor microstructure and mechanical properties of metallic materials to overcome the strength-ductility trade-offdilemma.In this work,we combined a novel alloy design prin-ciple,i.e.harvesting pronounced solid solution hardening (SSH) based on the misfit volumes engineering,and simultaneously,architecting the ductile matrix based on the valence electron concentrations (VEC)criterion,to fulfill an excellent strength-ductility synergy for the newly emerging high/medium-entropy alloys (HEAs/MEAs).Based on this strategy,Al/Ta co-doping within NiCoCr MEA leads to an efficient synthetic approach,that is minor Al/Ta co-doping not only renders significantly enhanced strength with notable SSH effect and ultrahigh strain-hardening capability,but also sharply refines grains and induces abnormal twinning behaviors of (NiCoCr)92Al6Ta2 MEA.Compared with the partially twinned NiCoCr MEA,the yield strength (σy) and ultimate tensile strength (σUTS) of fully twinned Al/Ta-containing MEA were increased by ～102 ％ to ～600 MPa and ～35 ％ to ～ 1000 MPa,respectively,along with good ductility beyond 50 ％.Different from the NiCoCr MEA with deformation twins (DTs)/stacking faults (SFs) domi-nated plasticity,the extraordinary strain-hardening capability of the solute-hardened (NiCoCr)92Al6Ta2 MEA,deactivated deformation twinning,originates from the high density of dislocation walls,micro-bands and abundance of SFs.The abnormal twinning behaviors,i.e.,prevalence of annealing twins (ATs)but absence of DTs in (NiCoCr)92Al6Ta2 MEA,are explained in terms of the relaxation of grain boundaries(for ATs) and the twinning mechanism transition (for DTs),respectively.     

水泥中MgO膨胀剂水化产生的膨胀应力表征

本文研制了一套膨胀应力测试装置,并以此为基础测试了约束条件下MgO膨胀剂(MEA)压实体和掺MgO膨胀剂水泥浆体中水化产生的膨胀应力;采用X射线衍射法定量分析了MgO的含量,并计算MgO的水化程度。结果表明:活性指数为23s和46s的MgO膨胀剂压实体水化22d产生的膨胀应力分别为38.9MPa和62.7MPa;掺水泥浆体的膨胀应力随MEA掺量增大、MEA活性指数提高和MgO水化程度增加而增大,不掺MgO膨胀剂的水泥浆体63d时的收缩应力为1.3MPa,掺12%活性指数为23s和46s的MgO膨胀剂水泥浆体在63d时的膨胀应力分别为1.8MPa和3.0MPa。     

质子交换膜燃料电池膜电极的结构优化

膜电极(membrane electrode assembly,MEA)是质子交换膜燃料电池(proton exchange membrane fuel cell,PEMFC)的核心部件,为PEMFC提供了多相物质传递的微通道和电化学反应场所。为了实现燃料电池商业化目标,需要制备高功率密度、低Pt载量、耐久性好的MEA。在MEA中除了催化剂以外,各功能层结构、层与层之间的界面都对MEA的性能具有重要影响。传统方法(CCS法和CCM法)制备的MEA在结构上有很多缺陷,明显制约了Pt的利用率和系统传质能力。通过优化各功能层结构消除缺陷,将有利于进一步提升PEMFC综合性能。本文从传统MEA结构存在的问题出发,梳理了近年来关于催化层、质子交换膜和气体扩散层结构优化方面的文献,归纳总结了各先进结构的制备方法、构效关系以及优缺点,对未来高性能、低成本和长寿命的MEA的开发具有指导意义。     

直接甲醇燃料电池MEA材料的研究及制作进展

综述了近年来直接甲醇燃料电池的膜电极制作材料的研究、质子交换膜的研究、电极结构的研究、MEA的制作工艺等。     

Production new chelating fibers of polyacrilonitrile for removing metal ions

In this work, raw acrylic fibers (RAF) have been modified with ethanolamine to provide new chelating fibers and prepared polyacrylonitrile‐monoethanolamine (PAN‐MEA). PAN‐MEA fiber was prepared by conversion nitrile groups into hydroxyle groups using ethanolamine solution with different concentration under refluxing at different temperatures and different times. The fiber structure has been investigated by different experimental techniques of characterization such as Fourier transform infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and the physical and mechanical properties has also been investigated in this study. The PAN‐MEA was examined as chelating material in a series of batch adsorption experiments for removal Cu (II), Pb (II) and Ni (II) ions. The ion adsorption of PAN‐MEA was determined with the atomic adsorption method. PAN‐MEA show adsorption metal ions more than usual fiber because of the modification.     

Microelectrode Array-evaluation of Neurotoxic Effects of Magnesium as an Implantable Biomaterial

Magnesium(Mg)-based biomaterials have shown great potential in clinical applications. However,the cytotoxic effects of excessive Mg~(2+) and the corrosion products from Mg-based biomaterials,particularly their effects on neurons,have been little studied. Although viability tests are most commonly used,a functional evaluation is critically needed. Here,both methyl thiazolyl tetrazolium(MTT) and lactate dehydrogenase(LDH) assays were used to test the effect of Mg~(2+) and Mg-extract solution on neuronal viability.Microelectrode arrays(MEAs),which provide long-term,real-time recording of extracellular electrophysiological signals of in vitro neuronal networks,were used to test for toxic effects. The minimum effective concentrations(EC_(min)) of Mg~(2+) from the MTT and LDH assays were 3 mmol/L and 100 mmol/L,respectively,while the EC_(min) obtained from the MEA assay was 0.1 mmol/L. MEA data revealed significant loss of neuronal network activity when the culture was exposed to 25% Mg-extract solution,a concentration that did not affect neuronal viability. For evaluating the biocompatibility of Mg-based biomaterials with neurons,MEA electrophysiological testing is a more precise method than basic cell-viability testing.     

Bibliometric analysis of diabetes mellitus research output from Middle Eastern Arab countries during the period (1996–2012)

The main objective of this study was to analyze research productivity originating from Middle East Arab (MEA) countries in the field of diabetes mellitus (DM). Data from January 1, 1996 till December 31, 2012 were searched for documents with specific words in diabetes as a “source title” and a list of 13 MEA countries as affiliation country. Research productivity was evaluated based on number of publications, citation analysis, indexing in Institute for Scientific Information and impact factor (IF). The 13 MEA countries published a total of 479 documents in 41 diabetes journals. This number represents 0.75 % of the total documents produced globally in the field of DM. The number of published documents increased by around fivefold from early 2000 to 2012. Of the 41 journal titles retrieved, 24 (58.5 %) had their IF listed in the journal citation reports 2012. Forty-two documents (14.5 %) were published in journals that had no official IF. The total number of citations for documents published from MEA countries in the field of DM, at the time of data analysis, was 5,565 with an h index of 35. The median (inter-quartile range) citation for documents from the 13 MEA countries was 4 (1–11). The top productive institution in the field of DM was United Arab Emirates University with 51 documents (10.6 %). Authors from MEA countries collaborated mostly with authors in countries like United Kingdom, USA, and Germany. The present data show promising and relatively good diabetes research productivity in MEA countries especially after 2008.     

Fabrication of a nanosize-Pt-embedded membrane electrode assembly to enhance the utilization of Pt in proton exchange membrane fuel cells

A procedure to locate the Pt nanostructure inside the hydrophilic channel of a Nafion membrane was developed in order to enhance Pt utilization in PEMFCs. Nanosize Pt-embedded MEA was constructed by Cu electroless plating and subsequent Pt electrodeposition inside the hydrophilic channels of the Nafion membrane. The metallic Pt nanostructure fabricated inside the membrane was employed as an oxygen reduction catalyst for a PEMFC and facilitated effective use of the hydrophilic channels inside the membrane. Compared to the conventional MEA, a Pt-embedded MEA with only 68% Pt loading showed better PEMFC performance.     

PEMFC膜电极电催化层的制备和性能

膜电极催化层的组成和电催化剂的活性对质子交换膜燃料电池的性能有很大影响．采用浸渍还原法制备出了Pt平均粒径为3．1nm的Pt／C催化剂．催化剂中Pt的粒径和在碳黑载体（VulcanXC-72）表面的分散程度采用透射电镜（TEM）进行测试．用Pt／C催化剂、适量的Nation溶液和PrFE乳液制备出质子交换膜燃料电池（PEMFc）膜电极的催化剂层,并研究了该催化剂层中PTFE含量对其性能的影响．实验表明,PTFE强烈的疏水性可以迫使部分水分向阳极反扩散,催化层中加入适量的PTFE可以使膜电极具有一定的水管理能力,在去掉辅助增湿系统的条件下具有良好的极化性能．     

Effect of amine structure on CO2 capture by polymeric membranes

Abstract

Poly(amidoamine)s (PAMAMs) incorporated into a cross-linked poly(ethylene glycol) exhibited excellent CO₂ separation properties over H₂. However, the CO₂ permeability should be increased for practical applications. Monoethanolamine (MEA) used as a CO₂ determining agent in the current CO₂ capture technology at demonstration scale was readily immobilized in poly(vinyl alcohol) (PVA) matrix by solvent casting of aqueous mixture of PVA and the amine. The resulting polymeric membranes can be self-standing with the thickness above 3 μm and the amine fraction less than 80 wt%. The gas permeation properties were examined at 40 °C and under 80% relative humidity. The CO₂ separation performance increased with increase of the amine content in the polymeric membranes. When the amine fraction was 80 wt%, the CO₂ permeability coefficient of MEA containing membrane was 604 barrer with CO₂ selectivity of 58.5 over H₂, which was much higher than the PAMAM membrane (83.7 barrer and 51.8, respectively) under the same operation conditions. On the other hand, ethylamine (EA) was also incorporated into PVA matrix to form a thin membrane. However, the resulting polymeric membranes exhibited slight CO₂-selective gas permeation properties. The hydroxyl group of MEA was crucial for high CO₂ separation performance.     

Ternary Complexes of Flurbiprofen with HP-ß-CD and Ethanolamines Characterization and Transdermal Delivery

ABSTRACT

Binary and multicomponent systems complexes prepared with HP-ß-CD and/or with monoethanolamine (MEA), diethanolamine (DEA) or triethanolamine (TEA) were obtained.

The results of solid-state studies indicated the presence of strong interactions between the components in the binary and the ternary systems. Drug solubility and dissolution rate in water were notably improved by employing the HP-ß-CD and the alkanolamines. The combined use of cosolvency and complexation with MEA in the presence of HP-ß-CD on the permeation of flurbiprofen through the human skin was evaluated. The combination of IPM, PG, and HP-ß-CD yield the highest permeation for the flurbiprofen–MEA complex.     

质子交换膜燃料电池CCM的制备条件对其性能的影响

采用催化剂涂覆的膜(CCM)和碳纸扩散层组成质子交换膜燃料电池的膜电极.CCM采用直接喷涂的方法制备,研究了与直接喷涂技术相关的影响因素,包括催化层中Nafion的含量和分布、有机溶剂的种类、喷涂操作条件等.CCM的表面形貌和孔结构采用扫描电镜(SEM)方法表征,MEA的电化学特性通过单体PEMFC的I-V曲线进行评价.实验结果表明,在优化条件下制备的CCM膜电极的结构和性能有明显的改善.     

Pulsed Activation of a Fuel Cell on the Basis of a Proton-Exchange Polymer Membrane

The influence of pulsed activation on the electrochemical characteristics of fuel cells based on the Nafion proton-conducting membrane is studied. The activation was a repeated pulsed operation of the membrane–electrode assembly (MEA), which was characterized by alternating a constant load of the MEA near a short-circuit current at voltage U_L = 0.1 V and its “idle time” corresponding to the open circuit voltage of the MEA, U_OCV ≈ 0.95 V. It is shown that there is an optimal ratio of the time parameters of the pulsed load at which the activation is much more efficient than in the case of constant potentiostatic or galvanostatic regimes often used in practice.     

Synthesis of offretite: Part 2. Using a combination of tetramethylammonium cations and monoethanolamine or 1,2-diaminoethane as template

In the synthesis of offretite, tetramethylammonium (TMA) cations are preferentially located in the gmelinite cages. Additional TMA cations, monoethanolamine or 1,2-diaminoethane molecules are then needed to ensure that the linear channels of the offretite are maintained. However, when either MEA or DAE is used, stricter adherence to the optimum synthesis conditions is necessary to avoid excess alkali in the product. The substitution of either MEA or DAE for TMA leads to different crystallite morphologies.     

Multinozzle emitter arrays for nanoelectrospray mass spectrometry

Mass spectrometry (MS) is the enabling technology for proteomics and metabolomics. However, dramatic improvements in both sensitivity and throughput are still required to achieve routine MS-based single cell proteomics and metabolomics. Here, we report the silicon-based monolithic multinozzle emitter array (MEA) and demonstrate its proof-of-principle applications in high-sensitivity and high-throughput nanoelectrospray mass spectrometry. Our MEA consists of 96 identical 10-nozzle emitters in a circular array on a 3 in. silicon chip. The geometry and configuration of the emitters, the dimension and number of the nozzles, and the micropillar arrays embedded in the main channel can be systematically and precisely controlled during the microfabrication process. Combining electrostatic simulation and experimental testing, we demonstrated that sharpened-end geometry at the stem of the individual multinozzle emitter significantly enhanced the electric fields at its protruding nozzle tips, enabling sequential nanoelectrospray for the high-density emitter array. We showed that electrospray current of the multinozzle emitter at a given total flow rate was approximately proportional to the square root of the number of its spraying-nozzles, suggesting the capability of high MS sensitivity for multinozzle emitters. Using a conventional Z-spray mass spectrometer, we demonstrated reproducible MS detection of peptides and proteins for serial MEA emitters, achieving sensitivity and stability comparable to the commercial capillary emitters. Our robust silicon-based MEA chip opens up the possibility of a fully integrated microfluidic system for ultrahigh-sensitivity and ultrahigh-throughput proteomics and metabolomics.     

Influences of organic ligands on the microstructure and properties of sol-gel antimony-doped tin oxide thin films

The antimony-doped tin oxide (ATO) thin films were prepared by sol-gel dip-coating process from SnCl2 2H2O and SbCl3 in alcoholic solutions. The influences of organic ligands, including acetic acids (HAc), acetic acids with monoethanolamine (in brief HAc + MEA), and acetic acids with acetylacetone (in brief HAc + AcAc), on the the microstructure and electrical properties of the thin films have been investigated. The thermal behavior of the ATO gels powders and the microstructures of the thin films have been characterized by using thermogravimetric (TG), differential scanning calorimetric (DSC), Fourier transform infra-red spectral (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) analysis. The electrical resistivity of the thin films was detected by four-probe instrument measurement. The thin films with HAc + MEA as coordination ligands had a good crystal quality and showed a preferred orientation along (101) plane when heated at 450 degrees C. As a consequence, it exhibited the best electrical performance. An electrical resistivity of about 6.3 x 10(-3) omega cm could be achieved for the films with 500 nm thickness.     

改进的思维进化算法在阵列天线综合中的应用

思维进化算法(Mind Evolutionary Algorithm,MEA)采用趋同和异化操作,通过模仿人类思维进化的过程进行寻优,克服了早熟现象,提高了算法的搜索能力.针对基本思维进化算法中产生初始种群的盲目性、补充淘汰临时子群体的单一性以及现有搜索方式易陷入小区域局部收敛的问题,提出了一种多混沌思维进化算法.该算法采用两种不同的混沌序列,提高了种群的多样性,扩大了搜索范围.将多混沌思维进化算法应用于等间距直线阵列天线综合.良好的仿真结果表明了多混沌思维进化算法在阵列天线综合的优越性.     

Deposition of platinum nanoparticles on organic functionalized carbon nanotubes grown in situ on carbon paper for fuel cells

Deposition of small Pt nanoparticles of the order of 2-2.5?nm on carbon nanotubes (CNTs) grown directly on carbon paper is demonstrated in this work. Sulfonic acid functionalization of CNTs is used as a means to facilitate the uniform deposition of Pt on the CNT surface. The organic molecules attached covalently to the CNT surface via electrochemical reduction of corresponding diazonium salts are treated with concentrated sulfuric acid and the sulfonic acid sites thus attached are used as molecular sites for Pt ion adsorption, which are subsequently reduced to yield the small Pt nanoparticles. Cyclic voltammograms reveal that, after removal of the organic groups during high temperature reduction, these Pt nanoparticles are in electrical contact with the carbon paper backing. A typical Pt loading of 0.09?mg?cm(-2) is achieved, that shows higher specific surface area of Pt than an E-TEK electrode with Pt loading of 0.075?mg?cm(-2). A membrane and electrode assembly (MEA) is prepared with a Pt/CNT electrode as cathode and an E-TEK electrode as anode, and it offers better performance than a conventional E-TEK MEA.