微化工过程研究进展

微化工过程是化学工程学科的研究前沿和热点方向之一,是实现化工过程安全、高效、绿色的重要途径.近年来,关于微化工过程的研究主要集中在微尺度多相流动与结构调控、微尺度混合与多相传递以及微尺度反应过程等方面,并且取得了显著的进展.本文主要针对以上几个方面的研究进展进行综述,分析总结了微化工过程的优势和特点,并对其未来的发展方向进行了展望.     

煤层气治理与利用技术研究开发进展

煤层气作为一种非常规天然气,既是宝贵的清洁能源,其主要成分甲烷同时也是一种主要的温室气体;煤层气的直接排放不仅加剧了大气温室效应和环境污染,同时也是能源资源的极大浪费.近年来,煤层气的治理和利用受到了广泛关注,有关技术研究和开发取得了很大进展.本文对近年来煤层气的治理和利用技术研发进展进行了总结和评估,侧重于介绍煤层气分离系统中关键的中、高浓度煤层气催化燃烧脱氧技术以及乏风瓦斯逆向流催化燃烧减排及余热利用技术.最后对煤层气综合利用技术进行了展望.     

Application of heat flow calorimetry to the study of oilwell cements

The majority of previous studies of the hydration of cements using heat flow calorimetry have been carried out isothermally. However, with oilwell cements the slurry is mixed on the surface at ambient temperature and then gradually increases in temperature as it is pumped down the well. A Setaram C-80 calorimeter has been used to simulate the temperature ramp in API oilwell cement test schedules. This approach has enabled cementing reactions to be studied for the first time under conditions approaching those encountered in the field, and has shown that the results obtained from isothermal experiments may be misleading.The permission of the British Petroleum Company PLC to publish this paper is gratefully acknowledged.     

聚乳酸-聚乙二醇单甲醚共混体系的调制DSC分析

采用调制差示扫描量热法(MDSC)研究了聚乳酸(PLA)与聚乙二醇单甲醚(MPEG)共混体系的热性能。研究结果表明,MDSC可有效分辨PLA重结晶和熔融的重叠效应,在测试条件下,PLA的α’-α晶型转变与α晶体的熔融几乎同时进行。随着升温速率的加快和调制周期的延长,当增塑剂的质量分数为15%时,PLA-MPEG共混物分割在不可逆曲线的重结晶焓逐渐升高(最高约28J/g),熔融焓逐渐降低(最低约为3.3J/g);分割在可逆曲线的熔融峰逐渐由多重峰变为单峰,且焓变值逐渐升高(最高约66.1J/g),相应的可逆曲线熔融分割比例达到了95.2%。通过提高升温速率和延长调制周期,可使大部分熔融分割在可逆曲线上,但过快的升温速率和过长的调制周期会导致PLA相转变时的周期数过少,DSC调制功能的分辨率下降,设置测试条件时需综合考虑。     

A flow microcalorimeter for measuring the heats of mixing of binary liquids by A continuous process

In order to measure heats of mixing or heats of dilution for many solutions by a continuous process accurately, a twin conduction type flow microcalorimeter has been constructed, improving the design of the same type of calorimeter reported previously. The thermal stability of the heat sink was enhanced by enlarged contact area of the main heat sink block with a thermostated water bath. Mixing efficiency of the mixing cell and the stability of the base line were improved by the use of a new mixing cell having a long mixing zone and symmetrically arranged sample and reference cells. Waiting time for establishment of thermal steady state was also reduced by sandwiching each of the cell by a pair of wide thermopiles plates and a pair of sub-blocks. Heats of dilution of aqueous urea solutions were measured by a continuous process, and results obtained well agreed with accepted values by Guckeret al. The accuracy and thermal resolution in this calorimeter were estimated to be less than 0.05% and 3 J·s^–1.The authors are grateful to Professor S. Murakami of Osaka City University for helpful discussion.     

调制式DSC在高聚物研究中的应用

综述了一种新的热分析技术－－调制式差示扫描量热示（Modulated Differentail Scanning Calorimetry）。对其工作原理，优点及在高聚物研究中的应用作了简介。     

聚合物长支链的流变学表征方法

在聚合物中引入长支链能够显著地提高熔体强度,改善聚合物在拉伸流场中的加工性能,因此对长支链的表征显得十分重要。流变学被证实是一种非常有效且敏感的表征手段,近来受到普遍关注。本文总结了近年来国内外关于长支链聚合物流变学表征研究的最新进展,比较了不同类型流场下对长支链的流变学判断方法,尽量结合高分子链段分子结构解释了各种表征现象的含义,阐述了借助流变学对大分子拓扑结构的定性表征以及对长支链含量的定量表征方面的应用。     

DSC Study on Brain Tubulin and the Effect of Cisplatin

Microtubules, a class of cytoskeletal elements, appear to be present in all eukaryoticcells. The temporal and spatial control of assembly and disassembly of microtubulesis believed to be a key factor in cellular function. Microtubules and their subunits(Q-0 tubulin heterodimers, MW 1 10,000) maintain a dynamic equilibrium in the cellcytoplasm. In addition, it is postulated that the lability of cytoplasmic microtubulescaused by drug is related to their equilibrium. Calorimetry method has been…     

MHD Stagnation Point on Nanofluid Flow and Heat Transfer of Carbon Nanotube over a Shrinking Surface with Heat Sink Effect

This study is to investigate the magnetohydrodynamic (MHD) stagnation point flow and heat transfer characteristic nanofluid of carbon nanotube (CNTs) over the shrinking surface with heat sink effects. Similarity equations deduced from momentum and energy equation of partial differential equations are solved numerically. This study looks at the different parameters of the flow and heat transfer using first phase model which is Tiwari-Das. The parameter discussed were volume fraction nanoparticle, magnetic parameter, heat sink/source parameters, and a different type of nanofluid and based fluids. Present results revealed that the rate of nanofluid (SWCNT/kerosene) in terms of flow and heat transfer is better than (MWCNT/kerosene) and (CNT/water) and regular fluid (water). Graphically, the variation results of dual solution exist for shrinking parameter in range λc<λ≤−1 for different values of volume fraction nanoparticle, magnetic, heat sink parameters, and a different type of nanofluid. However, a unique solution exists at −1<λ<1, and no solutions exist at λ<λc which is a critical value. In addition, the local Nusselt number decreases with increasing volume fraction nanoparticle when there exists a heat sink effect. The values of the skin friction coefficient and local Nusselt number increase for both solutions with the increase in magnetic parameter. In this study, the investigation on the flow and heat transfer of MHD stagnation point nanofluid through a shrinking surface with heat sink effect shows how important the application to industrial applications.     

Effects of the type of calorimeter and the use of plasticizers and hydrophobizers on the measured hydration heat development of FGD gypsum

Thermal phenomena at the hydration of calcium sulphate hemihydrate (CaSO₄·0.5H₂O) are investigated in the paper. Time development of hydration heat of β-calcium sulphate hemihydrate prepared from flue gas desulphurization (FGD) gypsum is determined using two different types of calorimeter, namely the differential calorimeter DIK 04 and the isothermal heat flow calorimeter KC 01, and the differences in measured data analyzed. Then, the effects of plasticizers and hydrophobizers on the hydration process of analyzed gypsum mixtures are studied.     

Temperature and Heat Flow Calibration of A DSC-instrument in the Temperature Range Between −100 and 160°C

Thermoanalytical instruments are extensively used in R&D as well as in industrial quality control. A quantitative analysis of the data of a thermoanalytical measurement requires a careful calibration of the instrument. In differential scanning calorimetry (DSC) the quantities that have to be calibrated are the temperature and the heat flow. These two quantities are usually calibrated by evaluating melting or solid-solid transitions of some reference materials with well known transition enthalpies and temperatures. In this contribution we investigate temperature and heat flow calibration in the temperature range between −100 and 160°C. We included 9 different samples for the analysis and established some general rules for the calibration process. As a result we found that with a well calibrated instrument the heat flow can be measured with 90% confidence to about ± 3% accuracy in this temperature range. With respect to temperature calibration we find that accuracies of ±0.8°C (90% confidence) may be expected. These values represent general accuracy limitations of DSC’s due to varying heat transfer conditions within the samples. This revised version was published online in July 2006 with corrections to the Cover Date.     

A Modulated Differential Scanning Calorimetric study

Modulated Differential Scanning Calorimetry^? has been applied to frozen sucrose solutions in the concentration range 10–80% w/w. The results from this study present, for the first time, information on the reversing and non-reversing nature of events that occur in these solutions. The study demonstrates the potential benefits of this new technique to help separate complex transitions that can occur in the total heat-flow curves obtained using traditional differential scanning calorimetry. The results illustrate how this new technique can separate the different enthalpic events, which relate to the glass transition and the onset of ice dissolution that occurs during the heating of these frozen systems, by nature of their “reversing” and “non-reversing” contributions to the total heat flow.     

低浓度甲烷流向变换催化燃烧的研究

甲烷在煤矿工业中被称作为瓦斯,在富含甲烷的矿井中甲烷的体积分数为0．1％～1．0％,在煤矿开采过程中甲烷的体积分数达到5％～15％就会造成瓦斯爆炸。如果能够将煤矿中的甲烷抽取出来利用,不但可以减少矿难事故的发生,而且能够提供更多可利用的清洁能源。因此,如何将此低品位的资源转化为可利用的能源,具有重要的研究价值。另外,甲烷的温室效应是CO2的21倍。因此,将伴随某些工业生产以及石油开采过程产生的低浓度甲烷直接排放到大气中,势必会造成严重后果。     

氨基酸与蛋白质体系热容研究

氨基酸与蛋白质都是生命现象和分子生物学研究的最基本和最重要的研究对象.利用热力学方法,特别是从热容的角度出发对其研究,对深入了解蛋白质的折叠与伸展、变性机理、稳定性及生命体的新陈代谢等问题均具有一定的意义.近年来,研究者们对蛋白质或氨基酸体系的热容研究做了大量工作,取得了很大进展,本文对此进行了概述。     

Poiseuille and extensional flow small-angle scattering for developing structure–rheology relationships in soft matter systems

As the rheoscattering community has grown, so has the breadth of experiments both in terms of materials systems, and also in terms of flow types and analysis approaches. In this review, we seek to highlight important recent developments in rheoscattering that go beyond simple shear measurements. In particular, this review will focus on Poiseuille flow and extensional flow small-angle scattering and results from recent experiments that lead to the development of structure–function relationships in a wide variety of soft materials.     

微型整体分析系统法及其进展

介绍了一种与微电子技术及微制造技术相关的微型整体分析系统,主要是有关以电渗流为基础的微型流动注射分析系统的发展。讲述了产生的原因和仪器的制备,近几年的发展,未业的发展趋势和应用。     

Identification of micro-scale calorimetric devices

Summary Using an RC model, the behavior of a TAM high-performance calorimeter (Thermometric AB, Sweden) equipped with a flow-mixing insertion vessel using independent pumps for each reactant is studied. The model shows a reliable sensitivity behavior for mixtures realized inside the cell. The model behavior is compared with experimental measurements.</o:p>     

微流控层流技术的研究

基于微型通道自身的层流特点而发展起来的多相层流技术，从最初的液-液微萃取开始，由于其结构加工简单、操作方便和分析功能强大，已逐渐发展成为一种加工分析方法，为微流控分析的研究应用打开了一个崭新的局面。本文概述了层流的基本原理，总结了近10年来在这方面的研究，包括层流界面间的分子扩散、转移现象和化学反应，以及层流刻蚀加工技术及其在制备纳米材料和在生命医学方面的应用。具体介绍了应用层流技术进行微芯片的加工制作，微型反应器的制备，离子、分子的分离分析，聚合物薄膜的形成和应用，微通道内有机合成反应的控制，溶液的浓度梯度控制以及在免疫检测中的应用，对细胞、生物大分子的操作控制，以及对生物试剂的预处理分析等。     

Fluorescence‐based lateral flow assays for rapid oral fluid roadside detection of cannabis use

With the recent worldwide changes in the legalization of marijuana, there is a significant need for rapid, roadside screening test for driving under the influence of drugs. A robust, sensitive, lateral flow assay has been developed to detect recent use via oral‐fluid testing for Δ⁹‐tetrahydrocannabinol (THC). This proof‐of‐concept assay uses a fluorescent‐based immunoassay detection of polymeric beads, conjugated to antibodies against native THC. The fluorescent technique allows for significantly lower limits of detection and higher precision determination of recent marijuana use without the use of urine or blood sampling—thus allowing for roadside identification. Detection levels of 0.01 ng/mL were distinguished from background and the lower limit of quantification was determined to approach 1 ng/mL.