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药物晶型转化与控制的研究进展 总被引:2,自引:1,他引:1
药物晶型可显著影响药品质量、安全性和有效性,国家"医药工业十二五发展规划"将药物晶型研究列为提升药物质量安全的主要任务和重点技术。本文介绍了药物多晶型的溶解度行为以及晶型转化的液相和固相介导机理,溶剂、添加剂/模板剂对药物晶型的控制有着重要的作用,而物理场效应(超声波、微波、超重力场等)对晶型转化过程起强化效应;过程分析技术的快速发展为晶型转化机理的研究以及过程优化、控制提供了先进手段。未来药物晶型转化与控制的研究将聚焦分子的组装与调控行为、过程分析以及药物的构效关系等方面。 相似文献
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以红辉沸石为原料,采用两步水热法将其转化为A型分子筛,系统地探讨A型分子筛的转化机理。对不同晶化时间的样品进行系统表征,深入解析天然红辉沸石转化A型分子筛的成核机制、生长控制、晶型稳定转化等结构基础问题。研究表明,A型分子筛的生长可分为3个阶段:在成核诱导期(晶化时间≤0.5 h),凝胶中的β笼通过双四元环构筑成α笼,生成较多晶核及少量1 μm小晶体;此后为快速生长期(晶化时间1~4 h),大量晶核通过聚集生长形成2 μm大晶体;在生长稳定期(晶化时间5~8 h),通过二次成核凝胶将会转化为更多的分子筛晶体。A型分子筛的形成遵循:铝硅酸盐凝胶→四元环、六元环→双四元环、β笼→α笼的晶化过程,因而其转化过程符合液相转化机理。 相似文献
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P_2O_5含量对石膏碳铵转化过程的影响 总被引:1,自引:0,他引:1
以纯 Ca SO4 · 2 H2 O添加水溶 P2 O5进行石膏碳酸铵溶液转化反应实验 ,探索 P2 O5含量对转化过程的影响。实验结果表明 ,石膏中水溶 P2 O5含量增加 ,SO4 2 -转化率下降 ,产物的物性变坏。 X衍射分析与扫描电镜观察发现 :石膏所含 P2 O5会改变转化过程的 Ca CO3 晶型及晶体形状 ,减缓了 Ca CO3 由球霞石型转为方解石型的速率 ,晶粒变细而不规则、粘结聚集包裹 Ca SO4 · 2 H2 O,形成产物层 ,增加传质阻力 ,降低转化率 ,使产物过滤性能变坏。因此 ,工业化过程中应将磷石膏水溶性 P2 O5控制在 1%以下 相似文献
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试验以磷石膏为原料,在以正己醇/十六烷基三甲基溴化铵(CTAB)/水构成的反相微乳液体系中制备α型半水石膏,并通过改变CTAB与水的比例(表水比)对晶体微观形貌进行调控,研究了反应温度、反应时间对磷石膏的脱水转化过程以及表水比对所得α型半水石膏晶体微观形貌的影响.结果表明,反相微乳液中磷石膏转化为α型半水石膏的过程需要一定的转化时间,且转晶速率与反应温度成正比.当反应温度为105℃、表水比为1.5时,磷石膏中的二水石膏5h即可完成向α型半水石膏的转化;α型半水石膏晶体尺寸随表水比的增大而减小,表水比从0.5增加到4.5的过程中,α型半水石膏的晶体平均长度由40μm降低至25μm,平均直径由6μm降低至500 nm. 相似文献
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本文介绍了天然气转化工艺过程中 型变换催化剂的使用情况 通过加强工艺管理,搞好气体净化,定期分析测定,正确判定催化剂活性,B109型催化剂使用寿命可长达11年,吨氨耗催化剂消耗量为0.0787kg。 并对使用寿命长的原因进行了分析。 相似文献
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分散染料的晶型对超细旦纤维染色的影响 总被引:2,自引:0,他引:2
本文从理论上分析了分散染料的晶型,提出了分散染料的晶型影响超细旦纤维染我的一个重要因素。用X-射线衍射,显微镜照像等方法检测了晶型转化现象,检测了C.I.分散红135晶型转化前后的粒度分布。 相似文献
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Masahiro Yoshida Xinghe Fan Hidekazu Yoshizawa Toshio Itahara Yoshinobu Kawano Yoshimitsu Uemura Yasuo Hatate 《Chemical Engineering Communications》2001,185(1):183-199
We synthesized a ferroelectric liquid crystal monomer possessing both carboxyl p-benzolxy-benzoate and carboxyl (s)-(-)-2-methylbutyl ester in its side chain. The liquid crystal and styrene monomers were utilized to form matrices of microspheres prepared by the dispersion or suspension polymerization. In this study, we characterized in detail physicochemical properties, thermo-responses, or electro-optical responses in the microspheres. We demonstrated the following results: (1) the volume-averaged diameters of microspheres prepared by the dispersion or suspension polymerization were of 1.5 or 45 μm, respectively, (2) the microspheres prepared showed liquid crystal abilities at the prescribed temperature, (3) the phase transition temperatures toward the liquid crystal phase of the microspheres prepared by copolymerizing the liquid crystal and styrene monomers could be decreased with increasing styrene monomer concentrations, and (4) the microspheres obtained remarkably exhibited electro-optical responses at the appointed voltage. 相似文献
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This paper investigates the enthalpy of solid phase transition of isotactic polypropylene from the mesomorphic phase to the monoclinic crystal form using DSC. iPP fibres with either monoclinic crystal form or mesomorphic phase were obtained by varying the conditions of melt spinning. XRD and mechanical tests were used to confirm the crystal forms. It is found that conventional DSC techniques fail to detect the transition enthalpy; a technique using silicon oil as the thermal medium was then employed to determine the transition enthalpy, which is of 3% the melting enthalpy for crystallites with monoclinic form, or 6.1 J/g on 100% crystallinity basis. 相似文献
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采用重结晶法在二甲基甲酰胺(DMF)/H2O、二甲基亚砜(DMS)O/H2O和N-甲基吡咯烷酮(NMP)/H2O等不同溶剂体系中得到FOX-7晶体,用扫描电子显微镜(SEM)测试晶体的形貌、变温X-射线粉末衍射(XRD)分析晶型和相变、差示扫描量热仪(DSC)测试其热性能。结果表明,不同溶剂重结晶得到的FOX-7晶体形貌有较大差别,在DMSO/H2O溶剂中得到的晶体质量要优于其他两种;3种溶剂中得到FOX-7晶体的晶型和相变过程相同,即常温下FOX-7的晶型为α晶型,在120℃时,FOX-7完成α→β相变,至185℃时,完成β→γ相变;重结晶的FOX-7晶体5s爆发点温度提高了4~9℃,说明热稳定性增强。 相似文献
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We have isolated ribulose-1,5-bisphosphate-carboxylase/oxygenase (RUBISCO) from the red algae Galdieria Sulphuraria. The protein crystallized in two different crystal forms, the I422 crystal form being obtained from high salt and the P21 crystal form being obtained from lower concentration of salt and PEG. We report here the crystallization, preliminary stages of structure determination and the detection of the structural phase transition in the P21 crystal form of G. sulphuraria RUBISCO. This red algae enzyme belongs to the hexadecameric class (L8S8) with an approximate molecular weight 0.6MDa. The phase transition in G. sulphuraria RUBISCO leads from two hexadecamers to a single hexadecamer per asymmetric unit. The preservation of diffraction power in a phase transition for such a large macromolecule is rare. 相似文献
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The effect of diglycerides (DG) on the phase transition of various polymorphic forms of normal triglycerides (TG) of sal fat
was investigated by differential scanning calorimetry. Three levels of DG, 5, 10 and 15%, were used. DG delayed the phase
transition of lower melting crystal forms to higher forms of TG when the samples were brought to a congealed state by rapid
cooling (20 C/min) and heated at rates ranging from 1.25 to 10 C/min; the extent depended on the level of DG and the rate
of heating. As the level of DG and the rate of heating increased, the delay in phase transition of crystal forms I → II →
III was more pronounced. The phase transition of crystal forms I, II and III to form IV was delayed at 5 and 10% levels of
DG, while at the 15% level the phase transition of form I to higher forms was completely stopped when the samples were tempered
at 0 C for 18 hr and heated at 10 C/min. DG at 10 and 15% levels retarded the phase transition of form IV to the most stable
(V) form of TG when the samples were tempered at 0 C for 1 hr followed by 3 hr at 26 C. 相似文献
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Mechanism of solid phase transformation of α to β form crystal of syndiotactic polystyrene (sPS) was investigated in supercritical CO2. The phase transformation occurred in the original pure α and mixed (α+β) form sPS in supercritical CO2 was traced as a function of temperature and pressure by means of wide angle X-ray diffraction (WAXD), differential scanning calorimetry (DSC). At appropriate temperature and pressure, sPS underwent solid phase transitions from α to β form. Higher temperature or higher pressure favored this transformation. Compared to the original pure α form sample, the original β form crystal in the mixed (α+β) form sample acted as the nucleus of β form crystal, so that reduced the transition temperature and pressure. 相似文献
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分别研究了温度对壬基酚聚氧乙烯醚(NP-10)/水体系和十二烷基聚氧乙烯醚(AEO12)/水体系形成的立方相液晶线性黏弹性的影响。5~23.5℃,NP-10/水体系形成的双连续立方相表现出明显的黏弹性特征,但其强度随温度的升高而降低,在15℃时有强度突变点;连续升温证明,由AEO12/水体系形成的不连续立方相在21.8~22.5℃存在玻璃态转化现象。 相似文献