目的:研究盐酸乐卡地平Ⅰ、Ⅱ晶型及无定型对制剂制备的影响,为其制剂开发及一致性评价提供理论基础。方法:采用X-射线粉末衍射(XRD)、红外分光光度(IR)和差式扫描量热(DSC)法鉴定盐酸乐卡地平的3种晶型;采用XRD法比较粉粹、研磨、加压...目的:研究盐酸乐卡地平Ⅰ、Ⅱ晶型及无定型对制剂制备的影响,为其制剂开发及一致性评价提供理论基础。方法:采用X-射线粉末衍射(XRD)、红外分光光度(IR)和差式扫描量热(DSC)法鉴定盐酸乐卡地平的3种晶型;采用XRD法比较粉粹、研磨、加压工艺,湿法制粒中黏合剂溶剂(水、乙醇)和干燥温度(50、60、70℃)对盐酸乐卡地平3种晶型稳定性的影响;比较3种晶型盐酸乐卡地平片在水、盐酸、p H 4.5醋酸盐缓冲液、p H 6.8磷酸盐缓冲液4种介质中的体外溶出度。结果:XRD显示,Ⅰ、Ⅱ晶型均有特征衍射峰,且2θ值不一致,无定型无特征衍射峰;IR显示,3种晶型具有不同的吸收强度和吸收峰数目;DSC显示,Ⅰ、Ⅱ晶型分别在194.6、207.3℃有明显吸热峰,无定型在86.1℃有明显吸热峰、299.8℃有放热峰。粉粹、研磨、加压及干燥温度对3种晶型转变均无影响;湿法制粒时水对晶型转变无影响,乙醇会引起Ⅰ晶型的晶型转变。除在盐酸中Ⅰ晶型与Ⅱ晶型片比较f_2=68外,4种介质中3种晶型盐酸乐卡地平片溶出度两两比较的f_2均小于50。结论:XRD、IR、DSC法均能鉴定盐酸乐卡地平的3种晶型。用Ⅰ晶型制备盐酸乐卡地平片时,湿法制粒应避免使用乙醇作为黏合剂溶剂,建议使用水。不同晶型会影响所制盐酸乐卡地平片的体外溶出度。展开更多
Surface cell Madelung constant is firstly defined in calculating surface free energy of nanosized crystal grains, which explains the physical performance of small crystals and may be great benefit to make surface anal...Surface cell Madelung constant is firstly defined in calculating surface free energy of nanosized crystal grains, which explains the physical performance of small crystals and may be great benefit to make surface analysis and study dynamics of crystal nucleus growth. A new approximative expression of surface energy and relevant thermodynamic data was used in this calculation. A new formula and computing method for calculating the Madelung constant a of any complex crystals is proposed, and surface free energies and surface electrostatic energies of nanosized crystal grains as well as Madelung constant of some complex crystals are theoretically calculated in this paper. The surface free energy of nanosized crystal grain TiO2 and surface electrostatic energy（absolute value） of nanosized crystal grain α-A12O3 are found to be the biggest among other crystal grains.展开更多
The plastic anisotropy of sheet metal is usually caused by preferred orientation of grains, developed by mechanical deformation and thermal treatment. In the present study, a Taylor-like polycrystal model suggested by...The plastic anisotropy of sheet metal is usually caused by preferred orientation of grains, developed by mechanical deformation and thermal treatment. In the present study, a Taylor-like polycrystal model suggested by Asaro and Needleman is applied to investigate the evolution of the anisotropic behavior of a face centered cubic (FCC) polycrystalline metal, which is considered having {111} 110 slip systems, by stretching it along an arbitrary direction after it has undergone a plane-strain compression that rationally simulates the cold rolling process of FCC polycrystalline pure aluminium. By using the Taylor-like polycrystal model, pole fgures are obtained to describe the texture development of polycrystalline aggregate after plane-strain compression, and then the plastic anisotropy of polycrystalline aggregate is evaluated by stretch- ing the polycrystalline aggregate in different direction in term of yield stress. According to the results, the contours of longitudinal fow stress in three-dimensional orientation space are given and analyzed. Experiment results similar to the prediction of planar anisotropy can be found in the literature written by Takahashi et al. that indirectly show the correctness of the prediction of non-planar plastic anisotropy by this analysis.展开更多
This paper presents a mechanism theory principle for equivalent substitution in kinematic chain of a higher pair for lower pairs. This is the opposite of the principle of the equivalent substitution of lower pairs for...This paper presents a mechanism theory principle for equivalent substitution in kinematic chain of a higher pair for lower pairs. This is the opposite of the principle of the equivalent substitution of lower pairs for a higher pair. Also presented here is a new approach for isomorphism identification in kinematic chains containing higher pairs(KCCHs). Based on this approach, an algorithm for generating nonisomorphic KCCHs has been developed. This algorithm is not restricted by the number of links, the degree of freedom or the number of higher pairs. Using this algorithm, nonisomorphic KCCHs can be generated automatically from the kinematic chains that contain only lower pairs. As an application of this algorithm, all the nonisomorphic KCCHs with N<10(N, the number of links), F≤3 (F, the degree of KCCHs), and H≤2(H, the number of higher pairs) are computer generated.展开更多
文摘目的:研究盐酸乐卡地平Ⅰ、Ⅱ晶型及无定型对制剂制备的影响,为其制剂开发及一致性评价提供理论基础。方法:采用X-射线粉末衍射(XRD)、红外分光光度(IR)和差式扫描量热(DSC)法鉴定盐酸乐卡地平的3种晶型;采用XRD法比较粉粹、研磨、加压工艺,湿法制粒中黏合剂溶剂(水、乙醇)和干燥温度(50、60、70℃)对盐酸乐卡地平3种晶型稳定性的影响;比较3种晶型盐酸乐卡地平片在水、盐酸、p H 4.5醋酸盐缓冲液、p H 6.8磷酸盐缓冲液4种介质中的体外溶出度。结果:XRD显示,Ⅰ、Ⅱ晶型均有特征衍射峰,且2θ值不一致,无定型无特征衍射峰;IR显示,3种晶型具有不同的吸收强度和吸收峰数目;DSC显示,Ⅰ、Ⅱ晶型分别在194.6、207.3℃有明显吸热峰,无定型在86.1℃有明显吸热峰、299.8℃有放热峰。粉粹、研磨、加压及干燥温度对3种晶型转变均无影响;湿法制粒时水对晶型转变无影响,乙醇会引起Ⅰ晶型的晶型转变。除在盐酸中Ⅰ晶型与Ⅱ晶型片比较f_2=68外,4种介质中3种晶型盐酸乐卡地平片溶出度两两比较的f_2均小于50。结论:XRD、IR、DSC法均能鉴定盐酸乐卡地平的3种晶型。用Ⅰ晶型制备盐酸乐卡地平片时,湿法制粒应避免使用乙醇作为黏合剂溶剂,建议使用水。不同晶型会影响所制盐酸乐卡地平片的体外溶出度。
文摘Surface cell Madelung constant is firstly defined in calculating surface free energy of nanosized crystal grains, which explains the physical performance of small crystals and may be great benefit to make surface analysis and study dynamics of crystal nucleus growth. A new approximative expression of surface energy and relevant thermodynamic data was used in this calculation. A new formula and computing method for calculating the Madelung constant a of any complex crystals is proposed, and surface free energies and surface electrostatic energies of nanosized crystal grains as well as Madelung constant of some complex crystals are theoretically calculated in this paper. The surface free energy of nanosized crystal grain TiO2 and surface electrostatic energy（absolute value） of nanosized crystal grain α-A12O3 are found to be the biggest among other crystal grains.
基金Project supported by the National Natural Science Foundation of China(No.50371070),the Aviation Science Foun-dation of China(No.01C53015)and the Doctoral Foundation of Northwestern Polytechnical University.
文摘The plastic anisotropy of sheet metal is usually caused by preferred orientation of grains, developed by mechanical deformation and thermal treatment. In the present study, a Taylor-like polycrystal model suggested by Asaro and Needleman is applied to investigate the evolution of the anisotropic behavior of a face centered cubic (FCC) polycrystalline metal, which is considered having {111} 110 slip systems, by stretching it along an arbitrary direction after it has undergone a plane-strain compression that rationally simulates the cold rolling process of FCC polycrystalline pure aluminium. By using the Taylor-like polycrystal model, pole fgures are obtained to describe the texture development of polycrystalline aggregate after plane-strain compression, and then the plastic anisotropy of polycrystalline aggregate is evaluated by stretch- ing the polycrystalline aggregate in different direction in term of yield stress. According to the results, the contours of longitudinal fow stress in three-dimensional orientation space are given and analyzed. Experiment results similar to the prediction of planar anisotropy can be found in the literature written by Takahashi et al. that indirectly show the correctness of the prediction of non-planar plastic anisotropy by this analysis.
文摘This paper presents a mechanism theory principle for equivalent substitution in kinematic chain of a higher pair for lower pairs. This is the opposite of the principle of the equivalent substitution of lower pairs for a higher pair. Also presented here is a new approach for isomorphism identification in kinematic chains containing higher pairs(KCCHs). Based on this approach, an algorithm for generating nonisomorphic KCCHs has been developed. This algorithm is not restricted by the number of links, the degree of freedom or the number of higher pairs. Using this algorithm, nonisomorphic KCCHs can be generated automatically from the kinematic chains that contain only lower pairs. As an application of this algorithm, all the nonisomorphic KCCHs with N<10(N, the number of links), F≤3 (F, the degree of KCCHs), and H≤2(H, the number of higher pairs) are computer generated.
