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HM Lu DC Yin YM Liu WH Guo RB Zhou 《International journal of molecular sciences》2012,13(8):9514-9526
The protein structural entries grew far slower than the sequence entries. This is partly due to the bottleneck in obtaining diffraction quality protein crystals for structural determination using X-ray crystallography. The first step to achieve protein crystallization is to find out suitable chemical reagents. However, it is not an easy task. Exhausting trial and error tests of numerous combinations of different reagents mixed with the protein solution are usually necessary to screen out the pursuing crystallization conditions. Therefore, any attempts to help find suitable reagents for protein crystallization are helpful. In this paper, an analysis of the relationship between the protein sequence similarity and the crystallization reagents according to the information from the existing databases is presented. We extracted information of reagents and sequences from the Biological Macromolecule Crystallization Database (BMCD) and the Protein Data Bank (PDB) database, classified the proteins into different clusters according to the sequence similarity, and statistically analyzed the relationship between the sequence similarity and the crystallization reagents. The results showed that there is a pronounced positive correlation between them. Therefore, according to the correlation, prediction of feasible chemical reagents that are suitable to be used in crystallization screens for a specific protein is possible. 相似文献
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The present work provides a critical review of polymer crystallization studies using SALS; experimental methods, analysis techniques, observations and their relations with respect to other techniques are discussed. Furthermore, the fact that nucleation might be accompanied by large scale density fluctuations has been investigated for the flow‐induced crystallization of iPB. SALS was applied to measure density and orientation fluctuations, whereas complementary results were obtained from optical microscopy. The observations from both crystallization and melting experiments seem to indicate that the detected density fluctuations result from the presence of weakly anisotropic structures, rather than being an indication of densification before the onset of crystallization.
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采用差示扫描量热仪(DSC)对聚乳酸/环氧化聚丁二烯抗冲聚乳酸树脂(PLA/PB(EPB))的结晶性能进行了考察,并与纯聚乳酸(PLA)的结晶行为进行了对比,研究了环氧化聚丁二烯(EPB)对PLA等温/非等温条件下结晶行为的影响规律。结果表明:聚丁二烯橡胶(PB)对PLA的结晶行为影响较小,而EPB对PLA的晶体完善程度影响较为明显。PLA和PLA/PB更倾向于在低温条件下结晶,而PLA/EPB20.9%和PLA/EPB46.5%更倾向于在高温条件下结晶。抗冲聚乳酸树脂的结晶速率高于纯PLA,并且随着EPB环氧化度的增大,抗冲聚乳酸树脂的结晶速率呈逐渐增大的趋势。 相似文献
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利用工业结晶器对间苯二甲酸结晶动力学模型进行了研究,用工业试验数据对模型中的参数进行了拟合,推导出了间苯二甲酸结晶的成核速率和生长速率的动力学表达式.结果表明,计算值与试验值符合较好.在此基础上,将模拟结果应用于间苯二甲酸装置扩产改造中的结晶器设计,实测结果表明:产品粒度较装置改造前明显增大,粒度分布更加合理,模拟计算... 相似文献
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《分离科学与技术》2012,47(7):1056-1061
Separation of acetic acid from acetic acid and water mixture was carried out by melt crystallization. The effect of the cooling rate, the amount of seeds, the seeding temperature, the sweating rate, and the sweating fraction on the distribution coefficient was investigated. The acetic acid was successfully separated by single-stage melt crystallization. As the sweating fraction is increased, the crystalline layers grown at lower cooling rates are purified more highly. Eventually, the crystallization rate is much more important than the sweating rate. The effective distribution coefficient ranges from 0.01 to 0.25 for the crystal growth rates of 1.2 × 10?6 m/s to 4 × 10?6 m/s. 相似文献
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环保型阻垢剂聚天冬氨酸对碳酸钙结晶过程的影响 总被引:4,自引:0,他引:4
利用测量电极电位的方法,就环保型阻垢剂聚天冬氨酸对碳酸钙的结晶过程进行了研究。结果表明,聚天冬氨酸对碳酸钙结晶的抑制程度与药剂的质量浓度在初始钙质量浓度为300mg/L时,近似于三次曲线,而初始质量浓度为400~600mg/L时两者关系近似于一次曲线。 相似文献
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《分离科学与技术》2012,47(5):1021-1033
Abstract Ice crystalline layers were prepared from a binary eutectic mixture of acetic acid and water using layer melt crystallization. The crystalline layers were obtained under the conditions of the cooling temperature at 269, 268, and 267 K, the feed compositions of 0.5, 1.0, and 5.0 wt% acetic acid, and the cooling rates of 0.1, 0.5, and 1.0 K/min. After crystallization, sweating operations were carried out for various crystalline layers obtained in crystallization. The effect of sweating on the impurity behavior inside crystalline layer was investigated. The crystalline layer formed in higher growth rate was purified more easily by sweating operations. Effective distribution coefficient in the sweating process was in the range of 0.2 to 0.01, which depended on the crystalline layers formed in crystallization process. Eventually, layer melt crystallization can be used for the treatment of acetic acid wastewater. 相似文献
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丙烯酰胺的结晶动力学 总被引:3,自引:0,他引:3
采用MSMPR连续结晶器研究了丙烯酰胺的成核 -生长动力学。实验结果表明 ,丙烯酰胺的晶体生长基本符合生长速率与粒度无关的ΔL定律。在小于 1 0 0 μm的晶体粒度范围内 ,存在大量的细小晶粒 ,分析了产生这种现象的 4种可能原因。得到结晶温度分别为 1 0、1 5、2 0℃时 ,丙烯酰胺的成核 -生长动力学模型分别为 :n0 =1 2 6× 1 0 - 5G3 6 6 、n0 =3 92× 1 0 - 5G2 92 、n0 =7 65× 1 0 - 5G3 31 。在 1 0~ 2 0℃内 ,丙烯酰胺的成核 -生长动力学级数为 4 30。动力学级数对温度敏感性较小 ,不能通过调节晶浆密度来控制晶体产品的主粒度。进行了丙烯酰胺结晶的应用研究 ,完成了连续三步式结晶新工艺的概念设计。 相似文献
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本研究利用激光散射法研究了不同浓度下磷酸介稳区宽度的变化,同时还系统地考察了降温速率、搅拌强度、晶种加入量及典型杂质离子对介稳区宽度的影响关系。结果表明,介稳区宽度随降温速率的增加而相应变宽,由此根据不同浓度和不同降温速率的磷酸介稳区数据得到磷酸的表观二次成核级数为3.3;搅拌强度的增加和晶种加入量的减小,均使得磷酸介稳区宽度呈现逐渐变窄的变化。几种典型的杂质离子对磷酸介稳区宽度加大的影响作用不同,Fe2+对介稳区宽度的作用最为明显,F-的影响效果相对最弱,按照影响效果的强弱区分为:Fe2+SO42-F-。 相似文献
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A process for the recovery and purification of terephthalic acid (TA) from alkali reduction wastewater is reported. TA was first precipitated from alkali reduction wastewater by acidification with sulfuric acid, and then the produced crude TA was dissolved in dimethylacetamide (DMA) so that crude TA could be purified from the solution by cooling crystallization. The results indicated that acidification could reduce the chemical oxygen demand of the wastewater by 83 %, and the purity of TA by crystallization could reach 99.91 %. A correlation was proposed in describing the solubility of crude TA in DMA from 303.4 to 358.65 K, which gives a mean relative discrepancy of less than 1.14 %. The cooling rate of the mother liquor had a large influence on the crystal size distribution. At an average cooling rate of 1.18 K min–1, the particle size distribution of TA was narrow and the average size was about 100 μm. In a bench‐scale study, it was demonstrated that the crystallized product can be recycled as the raw material for polyethylene terephthalate production. 相似文献