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51.
针对我国广泛应用的乙炔法氯乙烯合成固定床反应器,结合氯乙烯合成的反应动力学、催化剂的失活动力学,同时引入了传热方程,建立了完整的列管式氯乙烯合成固定床反应器的数学模型。将该模型用于工业生产,模拟了传热系数沿管长的变化,列管内反应温度沿管长的变化并与生产数据对比,验证了模型的正确性。最后分析了乙炔空速、冷却水温度对管内温度分布和乙炔转化率的影响。 相似文献
52.
采用微波辐照法制备了以聚氯乙烯(PVC)为骨架,邻苯二甲酸二烯丙酯(DAP)为支链的接枝聚合物PVC-g-DAP。通过红外光谱、差示扫描量热分析对聚合物的结构进行了表征,同时对聚合物的流变性能、耐热性和力学性能进行了测试分析。结果表明,DAP在微波辐照下成功接枝到PVC大分子链上,PVC-g-DAP聚合物只有1个Tg,且略高于PVC。PVC-g-DAP聚合物的流变性能较PVC有大幅度改善,同时力学性能、耐热性得到提升。 相似文献
53.
54.
Electrochemical Behavior of Single CuO Nanoparticles: Implications for the Assessment of their Environmental Fate 下载免费PDF全文
Giorgia Zampardi Jorg Thöming Hendrik Naatz Hatem M. A. Amin Suman Pokhrel Lutz Mädler Richard G. Compton 《Small (Weinheim an der Bergstrasse, Germany)》2018,14(32)
The electrochemical behavior of copper oxide nanoparticles is investigated at both the single particle and at the ensemble level in neutral aqueous solutions through the electrode‐particle collision method and cyclic voltammetry, respectively. The influence of Cl? and NO3? anions on the electrochemical processes occurring at the nanoparticles is further evaluated. The electroactivity of CuO nanoparticles is found to differ between the two types of experiments. At the single‐particle scale, the reduction of the CuO nanoparticles proceeds to a higher extent in the presence of chloride ion than of nitrate ion containing solutions. However, at the multiparticle scale the CuO reduction proceeds to the same extent regardless of the type of anions present in solution. The implications for assessing realistically the environmental fate and therefore the toxicity of metal‐based nanoparticles in general, and copper‐based nanoparticles in particular, are discussed. 相似文献
55.
Solubility isotherms of the ternary system (NH4Cl+CaCl2+H2O) were elaborately determined at T= (273.15 and 298.15) K by using the isothermal method. In the equilibrium phase diagram, there are two solubility branches corresponding to the solid phases CaCl2⋅6H2O and NH4Cl. Invariant point compositions are 36.32 wt% CaCl2 and 3.4 wt% NH4Cl at 273.15 K, and 45.86 wt% CaCl2 and 5.22 wt% NH4Cl at 298.15 K. A Pitzer-Simonson-Clegg thermodynamic model was applied to represent the thermodynamic properties of this ternary system and to construct a partial phase diagram of the ternary system at temperatures between (273.15 and 323.15) K. It was found in the predicted solubility phase diagram that the double salt 2NH4Cl⋅CaCl2⋅3H2O, found by other authors at (323.1 and 348.1) K, will disappear at temperatures below 298.15 K. Besides, it was found that there are two peritectic points in the ternary system with peritectic temperatures at 299.65 K and 298.15 K, and the former peritectic point falls just on the line between the composition points of NH4Cl and CaCl2⋅6H2O. According to phase rule, a solution made of this point will begin to crystallize at 299.65 K and end at 298 K and therefore can be acted as a “pseudo eutectic” phase change material (PCM). A heat storing and releasing experiment of 50 grams of the PCM was carried out, obtaining a satisfying result. 相似文献
56.
Yue WangAuthor Vitae Yasushi HasebeAuthor Vitae 《Sensors and actuators. B, Chemical》2011,155(2):722-729
Horseradish peroxidase (HRP) was chemically modified using cyanuric chloride (CC) as a linking agent onto a carbon felt (CF), which is a microelectrode ensemble of micro carbon fiber (>7 μm, diameter) with a random three-dimensional structure. The resulting HRP-modified CF (HRP-ccCF) exhibited well-defined redox waves based on the HRP heme FeIII/FeII redox couple at −0.23 V vs. Ag/AgCl (at pH 7.0), while the HRP-adsorbed CF (HRP-CF) showed no apparent redox couple in the same potential range, indicating that the chemical modification of HRP via CC facilitated the direct electron transfer (DET) between HRP and CF. The apparent heterogeneous electron transfer rate constant ks was estimated to be 35 s−1. Cyclic voltammetry and electrochemical impedance spectroscopy revealed that the interfacial properties (i.e., structure, morphology of enzyme-layer) of covalently modified HRP (HRP-ccCF) and physically adsorbed HRP (HRP-CF) are different, resulting in the difference in the electron transfer properties. The HRP-ccCF was successfully used as a working electrode unit in bioelectrocatalytic flow-through detector for highly sensitive amperometric determination of H2O2. Under the optimized conditions (i.e., applied potential, 0 V vs. Ag/AgCl; carrier flow rate, 3.25 ml/min; and carrier pH 7.0), the cathodic peak current of H2O2 linearly increased up to 3 μM (sensitivity, 1.94 μA/μM; the detection limit, 0.08 μM [S/N = 3]) with sample through-put of ca. 90 samples/h. 相似文献
57.
Mariana Emilia Rasa Orlando Christopher M.A. 《Sensors and actuators. B, Chemical》2009,142(1):308-315
A new approach for building a bio-conductive interface for enzyme immobilisation is described. This strategy permits very simple preparation of the enzyme biosensor and also reveals direct electron transfer features. A graphite-epoxy resin composite (GrEC) electrode modified with functionalised multi-wall carbon nanotubes (MWCNTs) immobilised by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide together with N-hydroxysuccinimide (EDC–NHS) in a chitosan (Chit) matrix was prepared and characterised by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in the presence of hexaammineruthenium (III) chloride. It was then used as a base for glucose oxidase (GOx) immobilisation by the simple method of crosslinking with glutaraldehyde (GA) with bovine serum albumin (BSA) as carrier protein. The resulting mediator-free biosensor was applied to the determination of glucose in amperometric mode at different applied potentials and the mechanism of reaction was also investigated by cyclic voltammetry, with and without dissolved oxygen in solution. Analytical parameters, as well as reproducibility, repeatability and stability were determined. Interferences were assessed using different compounds usually present in natural samples, such as wines, juices or blood, in order to evaluate the selectivity of the developed biosensor. The novel combination of carbon nanotubes immobilised with chitosan crosslinked with EDC–NHS and glucose oxidase immobilised by crosslinking with glutaraldehyde offers an excellent, easy to make biosensor for glucose determination without interferences. 相似文献
58.
煤矿井下抗静电阻燃塑料管接件 总被引:2,自引:0,他引:2
介绍煤矿井下用塑料管接件的实验研究,通过调整材料比及工艺,使材料性能达到了煤炭工业部MT181-88标准。 相似文献
59.
以氯乙烯和金属镁为原料,反应制得格氏试剂乙烯基氯化镁;再与β-紫罗兰酮发生加成反应得到合成维生素A的重要中间体乙烯基-β-紫罗兰醇。通过对反应条件和工艺的研究和优化,确定了最佳工艺条件为:金属镁与β-紫罗兰酮的摩尔比为1.3∶1.0,滴加β-紫罗兰酮的温度为0~5℃,在反应温度20~25℃时继续反应3~4h,得到乙烯基-β-紫罗兰醇的收率为98.0%,气相色谱(GC)分析含量为92.5%。该工艺条件得到了实验室放大的验证。 相似文献
60.
The geological repository of nuclear waste in concrete containers is a possible storage method explored by ANDRA (Agence Nationale
pour la gestion des Déchets RadioActifs).
The concrete must display a high confinement capacity for long periods, characterized by low transport properties and by the
acido-basic buffer of hydrated cement. During service life, these properties can be endangered by chemical attack of underground
water.
The cement type has an important influence on the concrete's performances. Then, it is essential to establish appropriate
mixtures with accurate components.
In this work an ordinary Portland cement and a fly ash and blast furnace slag blended cement are compared.
To determine confinement capacities, transfer properties and mortars microstructure were investigated.
To predict the long term behaviour, an ammonium nitrate test has been developed to enhance decalcification and to accelerate
hydrolysis of cementitious materials.
Measurement of degraded depth with time regarding calcium content was carried out. Impact of decalcification on transport
properties was evaluated.
Fly ash and blast furnace slag provide better properties for native mortars, and more particularly diffusion properties, but
not as much as necessary to limit leaching in degraded material by chemical attack. 相似文献