Sustained-release pellets of nifedipine using microcrystals combined with MCC-based matrix

The purpose of this study was to prepare sustained-release pellets of nifedipine (NSPs) based on MCC matrix. Wet-milling and extrusion-spheronization techniques were employed to prepare the microcrystals and pellets, respectively. The drug release mechanism and the influencing factors were investigated. After milled with HPMC (E5), the mean particle size of nifedipine in co-grinding mixture (CGM) was 5?μm, which is 15-fold smaller than that of raw material. DSC, X-ray powder diffraction and microscopic observation confirmed the microcrystals of drug were maintained in the CGM. With increased milling time and the content of HPMC, the dissolution rate was greatly enhanced compared with the raw material. The NSPs prepared by MCC and the CGM, which was obtained by cogrinding nifedipine with 5% HPMC solution for 210?min, exhibited sustained release pattern within 8?h. Nifedipine release from MCC-based NSPs followed the Korsmeyer model and closely related to the microstructure of pellet. High stability of NSPs was confirmed after 6 months of accelerated stability test. Using commercially available sustained product as reference, bioequivalence study in beagle dogs was executed and two formulations were bioequivalent. This sustained release pellet formulation of nifedipine was advantageous with convenient and easy scaled-up preparation process.     

冯家塔煤矿采空区隐蔽火源位置探测

在分析冯家塔煤矿1201、1202、1203工作面采空区自然发火情况的基础上,采用同位素测氡法分两次探测了采空区隐蔽火区的范围,详细查明了采空区隐蔽火源的平面分布位置、立面具体位置,为灭火方案的制定奠定了理论基础。     

全国煤炭矿业权分布规律研究

基于全国矿业权实地核查成果数据库,确认煤炭矿业权在我国所有矿业权中占绝对优势的地位。在此基础上,从矿业权性质、地域分布、矿山开采规模、开采方式、矿业权获取方式等方面系统统计分析了煤炭矿业权分布特点和规律;归纳分析了煤炭矿业权分布所反映的主要问题,提出下一步加强煤炭矿业权管理的建议。     

基于融合CDN构建未来智能内容管道

详细探讨了传统CDN向融合CDN的演进方案、融合CDN构建智能内容管道的方法及在管道中的作用.为了更好地支撑业务发展,融合CDN需要与承载网络相互渗透,具备网络感知、业务感知、用户感知三大能力.为了保障移动业务的更好体验,提出CDN的网络位置应该下移到无线网络中,并根据无线网络的特性进行适配和优化.     

基于Android手机的万用表设计

Android万用表设计,在分压电路、限流电路、滤波电路等基础上用7721_LP3结合STC12LE5A60S2和Bluetooth技术,实现高精度的测量,自动切换量程、功能,快速高精度A/D转换并把测量结果发送到手机端.可测量直流电压、电流,交流电压、电流,电阻、电容、频率、占空比.在网络技术的支持下,可以实现自动化生产中的低成本在线测量,远程分析决策.本设计是把手机和万用表集为一体,将万用表简化为一个测量单元,而现代人不可或缺的手机将成为显示和存储设备.大大提高了万用表的便携性和可拓展性,基于Android手机APP开发的灵活性和多样性,将可激发万用表的潜在功能,可作为各种电量输出传感器的检测与无线变送装置,实现真正名称意义上“万用”.     

基于扫描激光雷达的列车速度测量系统

针对传统列车速度测量装置存在量程小、调试复杂等问题,基于扫描激光雷达技术,设计了一套适用于高速列车动态限界测量的列车速度测量系统。将扫描激光雷达固定在距列车10m 左右的位置上,根据激光脉冲飞行时间测距原理,沿列车行驶方向对进入扫描范围内的列车车身逐点扫描,获得由测量点组成的车身轮廓信息;通过最小二乘拟合车厢测量点,得到列车行驶轨迹,确定列车行驶方向;采用分段线性差值确定相邻两次测量周期内列车行驶的距离,完成列车速度的测量。结果表明:该测速系统操作方便,量程可达600km/h,测速误差控制在1.2%以内,可以满足高速列车速度测量需求。