An emulsion-congealing technique is used to prepare solid lipid microparticles （SLM） containing ibuprofen with glyceryl behenate, tripalmitin and beewax as excipients. The difference of the solubility parameters bet...An emulsion-congealing technique is used to prepare solid lipid microparticles （SLM） containing ibuprofen with glyceryl behenate, tripalmitin and beewax as excipients. The difference of the solubility parameters between the excipients and ibuprofen are used to analyze their compatibility. Both the solubility parameter analysis and the experimental results show that glyceryl behenate is the best among the three excipients. The solid particles disperse well in aqueous phase when the drug loading reaches 10% （relative to lipid only）. Glycerides exhibit marked polymorphism and their rapid rates of crystallization accelerate the formation of metastable crystal modification. The metastable crystal modification characterizes high drug loading capacity but less stability. Increasing the content of lipophilic drug in a lipid matrix facilitates the transformation of excipients to more stable polymorphic forms.展开更多
Horizontal directional solidification experiments were carried out with a monophasic Sn-2%Sb（mass fraction） alloy to analyze the influence of solidification thermal parameters on the morphology and length scale of t...Horizontal directional solidification experiments were carried out with a monophasic Sn-2%Sb（mass fraction） alloy to analyze the influence of solidification thermal parameters on the morphology and length scale of the microstructure. Continuous temperature measurements were made during solidification at different positions along the length of the casting and these temperature data were used to determine solidification thermal parameters, including the growth rate（VL） and the cooling rate（TR）. High cooling rate cells and dendrites are shown to characterize the microstructure in different regions of the casting, with a reverse dendrite-to-cell transition occurring for TR5.0 K/s. Cellular（λc） and primary dendrite arm spacings（λ1） are determined along the length of the directionally-solidified casting. Experimental growth laws relating λc and λ1 to VL and TR are proposed, and a comparative analysis with results from a vertical upward directional solidification experiment is carried out. The influence of morphology and length scale of the microstructure on microhardness is also analyzed.展开更多
以湖南鲁塘、湖南新化和陕西凤县典型矿区采集的不同石墨化度的天然煤系隐晶质石墨为研究对象,利用日本理学D/Max-2500PC型粉末X射线衍射仪和英国Renishaw in Via型显微拉曼光谱仪对煤系隐晶质石墨的晶体结构进行分析,通过表征不同石墨...以湖南鲁塘、湖南新化和陕西凤县典型矿区采集的不同石墨化度的天然煤系隐晶质石墨为研究对象,利用日本理学D/Max-2500PC型粉末X射线衍射仪和英国Renishaw in Via型显微拉曼光谱仪对煤系隐晶质石墨的晶体结构进行分析,通过表征不同石墨化度样品电阻率的变化,来探索石墨微晶结构与其导电性能的关系变化趋势。研究结果表明,室温时石墨的电阻率与其微晶层间距d002的变化趋势呈现正相关,而与其平均微晶尺寸La的变化趋势呈现负相关;煤系石墨成矿过程中,石墨化度的增加有利于石墨导电性能的形成,而石墨无序度增加则不利于石墨导电性能的形成。展开更多
基金Supported by the National Natural Science Foundation of China （No.20536020, No.20476033）, the China Distinguished Young Scientist Fund （No.20225620） and Guangdong Province Science Fund （No.04020121）.
文摘An emulsion-congealing technique is used to prepare solid lipid microparticles （SLM） containing ibuprofen with glyceryl behenate, tripalmitin and beewax as excipients. The difference of the solubility parameters between the excipients and ibuprofen are used to analyze their compatibility. Both the solubility parameter analysis and the experimental results show that glyceryl behenate is the best among the three excipients. The solid particles disperse well in aqueous phase when the drug loading reaches 10% （relative to lipid only）. Glycerides exhibit marked polymorphism and their rapid rates of crystallization accelerate the formation of metastable crystal modification. The metastable crystal modification characterizes high drug loading capacity but less stability. Increasing the content of lipophilic drug in a lipid matrix facilitates the transformation of excipients to more stable polymorphic forms.
基金the financial support provided by IFPA, Federal Institute of Education, Science and Technology of Para, FAPESP-Sao Paulo Research Foundation,Brazil (grants 2016/18186-1 and 2017/15158-0)CNPq,The Brazilian Research Council (grants 301600/2015-5 472745/2013-1 and 308784/2014-6)
文摘Horizontal directional solidification experiments were carried out with a monophasic Sn-2%Sb（mass fraction） alloy to analyze the influence of solidification thermal parameters on the morphology and length scale of the microstructure. Continuous temperature measurements were made during solidification at different positions along the length of the casting and these temperature data were used to determine solidification thermal parameters, including the growth rate（VL） and the cooling rate（TR）. High cooling rate cells and dendrites are shown to characterize the microstructure in different regions of the casting, with a reverse dendrite-to-cell transition occurring for TR5.0 K/s. Cellular（λc） and primary dendrite arm spacings（λ1） are determined along the length of the directionally-solidified casting. Experimental growth laws relating λc and λ1 to VL and TR are proposed, and a comparative analysis with results from a vertical upward directional solidification experiment is carried out. The influence of morphology and length scale of the microstructure on microhardness is also analyzed.
文摘以湖南鲁塘、湖南新化和陕西凤县典型矿区采集的不同石墨化度的天然煤系隐晶质石墨为研究对象,利用日本理学D/Max-2500PC型粉末X射线衍射仪和英国Renishaw in Via型显微拉曼光谱仪对煤系隐晶质石墨的晶体结构进行分析,通过表征不同石墨化度样品电阻率的变化,来探索石墨微晶结构与其导电性能的关系变化趋势。研究结果表明,室温时石墨的电阻率与其微晶层间距d002的变化趋势呈现正相关,而与其平均微晶尺寸La的变化趋势呈现负相关;煤系石墨成矿过程中,石墨化度的增加有利于石墨导电性能的形成,而石墨无序度增加则不利于石墨导电性能的形成。
