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61.
Sang Cheol Lee Won Kook Lee 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1992,55(3):251-261
The extraction of penicillin G from simulated media was performed by water/oil/water (w/o/w) emulsion liquid membranes (ELMs) and studied under various operational conditions in a batch system. The degree of extraction achieved was between 80% and 95% under specific conditions. A concentration of greater than nine times the initial concentration of penicillin G in the external phase was obtained in the internal phase. The pH of the internal aqueous solution, containing a basic salt, was theoretically calculated on the basis of the amount of penicillin G transported into the internal phase. The calculated results agreed with the experimental data well and were used to select a suitable type and concentration of a basic salt in the internal phase to give a pH within the range 5 to 8 where penicillin G was stable after the termination of extraction. The extraction of penicillin G was successfully performed by the ELM process with sodium carbonate in the internal phase. 相似文献
62.
本文研究了LF6铝合金的超塑性/扩散连接组合工艺,用变形和再结晶的方法细化晶粒,成功地进行了SPF/DB工艺试验,利用电子探针观察了扩散连接接头的界面微观区域,并从机理上分析了金属的超塑性/扩散连接两种工艺之间的内部联系及其金属学行为。 相似文献
63.
Quenching with gases rather than oil or other liquid media has the advantages of reducing the risks concerning health and environment, while simultaneously homogenizing the quenching results and minimizing distortion due to a wide range of possible process parameter variations and the pure convective heat transfer. In this contribution, a coupled solution for increasing homogenization of quenching results within high pressure gas quenching will be presented. In the first stage, an experimental test facility was set up for flow investigations and in the second stage a numerical simulation model was generated. The numerical and experimental results of the flow through the chamber were compared for several boundary conditions. Finally, after complete verification of the simulation, the model may be used to assist in parameter variation for optimization of homogeneous high pressure gas quenching. 相似文献
64.
This paper is the second dealing with measurement-related uncertainties of overcoring data undertaken at the Äspö Hard Rock Laboratory and focuses on the biaxial test data from CSIRO HI overcore samples. The first paper dealt with measurement-related uncertainties in connection with the overcoring phase [1].The uncertainties identified in connection to biaxial tests of CSIRO HI overcore samples include too large applied pressures and poor sampling frequency. At the Äspö HRL, the results yield that most overcore samples fractured during biaxial testing, meaning that a significant part, 56%, of available strain gauge combinations were removed from calculations of the elastic parameters. Remaining strain gauge combinations indicate average values of 62±5 GPa for Young's modulus and 0.25±0.01 for Poisson's ratio, which are considerably lower than previously published values [2–5], and are in good agreement with results from biaxial tests on Borre Probe overcore samples [6–10]. The stress calculations were obtained from re-analyzed elastic parameters and strains, and show primarily a reduction in stress magnitudes. Overall, the stress field obtained with different stress measurement methods and its variation with depth is now quite well resolved. The overcoring data suggest that the principal stresses are inclined with a vertical component dipping about 65° from the horizontal over the investigated rock volume (140–420 m depth). This is interpreted as a result of influence from the sub-vertical NE-2 Fracture Zone that divides the stress data into two stress domains [11], although it may also be an artefact because the σ2- and σ3-magnitudes are of the same order of magnitude. 相似文献
65.
Polymer blends based on polyolefins are of a great interest owing to their broad spectrum of properties and practical applications. However, because of poor compatibilities of components, most of these systems generally exhibit high interfacial tension, a low degree of dispersion and poor mechanical properties. It is generally accepted that polypropylene (PP) and nylon 6 (N6) are not compatible and that their blending results in poor materials. The compatibility can be improved by the addition of a compatibilizer, and in this study PP was functionalized by maleic anhydride (MAH) in the presence of an optimized amount of dicumyl peroxide (DCP). The reaction was carried out in the molten state using an internal mixer. Then, once the compatibilizer polypropylene‐graft‐maleic anhydride (PP‐g‐MAH) was prepared, it was added at various concentrations (2.5–10 wt%) to 30/70 glass fibre reinforced N6 (GFRN6) PP, and the mechanical properties were evaluated. It was found that the incorporation of the compatibilizer enhanced the tensile properties (tensile strength and modulus) as well as the Izod impact properties of the notched samples. This was attributed to better interfacial adhesion as evidenced by scanning electron microscopy (SEM). The optimum in these properties was achieved at a critical PP‐g‐MAH concentration. Copyright © 2005 Society of Chemical Industry 相似文献
66.
Lutgendorf Susan K.; Russell Daniel; Ullrich Philip; Harris Tamara B.; Wallace Robert 《Canadian Metallurgical Quarterly》2004,23(5):465
This study prospectively examined the relationship between religious attendance, interleukin-6 (IL-6) levels, and mortality rates in a community-based sample of 557 older adults. Attending religious services more than once weekly was a significant predictor of lower subsequent 12-year mortality and elevated IL-6 levels (> 3.19 pg/mL), with a mortality ratio of .32 (95% confidence interval [CI] = 0.15,0.72; p 相似文献
67.
Fault-based side channel cryptanalysis is very effective against symmetric and asymmetric encryption algorithms. Although straightforward hardware and time redundancy based concurrent error detection (CED) architectures can be used to thwart such attacks, they entail significant overhead (either area or performance). In this paper we investigate two systematic approaches to low-cost, low-latency CED for symmetric encryption algorithm RC6. The proposed techniques have been validated on FPGA implementations of RC6, one of the advanced encryption standard finalists. 相似文献
68.
以CHESS系统为例,介绍了差分跳频通信系统的基本原理,对其抗常规有意干扰的性能作了简要分析;在此基础上,初步探索了对CHESS系统进行侦察干扰的方法,并在计算机上对干扰效果进行了仿真比较。 相似文献
69.
70.
Solubility of dimethyl-2,6-naphthalene dicarboxylate in acetic acid, N,N-dimethylfonnamide, N,N-dimethyl acetamide, dimethyl sulphoxide, and N-methyl-2-ketopyrrolidine were determined using a dynamic method. The measured systems were correlated by UNIFAC group contribution method. A new main group (aromatic ester, ACCOO) was defined to express the activity coefficients of the aromatic ester. New interaction parameters of the ACCOO group were expressed as the first-order function of temperature and were determined from the experimental data. The calculated results for the new interaction parameters were satisfactory. The measured systems were also correlated with the Wilson and 2-h models, and the results were compared with those of the UNIFAC model. 相似文献