纳米结构ZnO晶体合成方法的研究进展

近年来,纳米结构ZnO在涂料、化妆品、橡胶和复合材料涂层等领域受到了广泛关注。纳米结构ZnO表面具有优异的表面效应与体积效应,故其磁性、光吸收特性、化学活性、催化活性、热阻及熔点等较普通粒子皆发生了很大的变化。纳米结构ZnO的合成方法主要包括水热合成法、化学气相沉积以及溶胶凝胶法。详细介绍了ZnO的结构及其物理性质,论述了几种常见的纳米结构ZnO制备方法,总结了不同制备方法合成纳米结构ZnO的研究进展,最后针对各合成方法的优缺点进行分析。

重庆儿科住院医师规范化培训的评价调查

目的以我国儿科住院医师规范化培训示范基地重庆医科大学附属儿童医院(简称重医儿院)为依托,探索评价现阶段儿科住培学员的规培效果。方法以重医儿院2009~2012年儿科医师住院规范化培训学员为调查对象,利用形成性评价的考核量表进行学员全程考核,主要包括住院医师规范化培训反馈调查表、住院医师规范化培训责任导师反馈调查表、住院医师规范化培训结业学员反馈调查表等,从临床、教学、科研三方面评价培训学员的培训质量。结果目前重医儿院儿科住院医师规范化培训学员逐渐年轻化,高学历学员人数逐年增加明显。各年级学员临床知识和技能培养评价较高。作为普通住院医师素质和能力过硬,能得到工作单位肯定。结论重医儿院住院医师规范化培训模式对提高学员总体培养质量有较好的促进作用,应不断改革和进一步探索。

铝基碳纳米管阵列超疏水表面的制备

为实现金属铝换热器表面的滴状冷凝以提高其传热效率和能源利用率,通过化学气相沉积法在金属铝表面直接生长得到具有高导热系数的垂直定向碳纳米管阵列超疏水结构,其高度和直径分别为7μm和30nm。采用正交试验法探究反应温度、反应时间、催化剂质量浓度以及溶液注射速率4个因素对疏水角大小的影响程度。结果表明:催化剂质量浓度和溶液注射速率对样品表面疏水性能的影响程度较大,反应温度和反应时间对样品表面疏水性能的影响程度较小,可以通过改变催化剂质量浓度和溶液注射速率进一步对样品接触角大小进行调控,得到理想疏水效果的铝基超疏水结构。

基于梯度感知的单幅图像超分辨

随着生成对抗网络在图像超分辨(SR)领域的应用,一些感知驱动的SR方法可以恢复出纹理细节更加丰富的SR图像,有效地缓解了由PSNR主导的SR方法导致重建图像趋于平滑的问题。然而梯度信息作为图像纹理的一种重要表现形式,鲜有SR方法能准确、高效地利用。为此,提出一种基于梯度感知的图像超分辨(GASR)算法,可以更准确地利用梯度信息。一方面,使用梯度域的特征图作为作用在图像域特征图上的卷积核,有效地避免了不同域特征图串联所带来的域冲突问题;另一方面,通过对卷积核尺寸等设计细节的调整使两个分支对应位置所输出的图像域与梯度域特征图的感受野一致。此外,由于实际应用对网络轻量化需求的提高,提出的GASR算法还有效降低了参数量和计算量。与同样利用梯度信息的SPSR相比,GASR最终以约1/6的参数量与1/10的计算量取得了与其相近的性能。在Set14数据集上,LPIPS与PSNR分别提升了0.0022与0.217。实验结果验证了GASR可以在纹理生成与图像平滑度之间取得一个很好的平衡,视觉化效果也验证了GASR不仅可以准确地恢复SR图像,而且在一定程度上缓解了杂乱纹理的生成。

Study of targeted and controlled release of 5-fluorouracil-loaded PLA nanoparticles and microspheres on treatment of gastric tumor

The aim of this paper was to evaluate controlled release behavior and the therapeutic efficacy of 5-FU-loaded Poly(lactic acid) (PLA)microspheres to human gastric cancer xenograft, and the targeting effect of VEGF/5-FU loaded PLA nanoparticles. 5-FU-loaded PLA microspheres were prepared by an emulsion evaporation method, and were characterized by scanning electron microscopy (SEM). 5-FU loaded PLA nanoparticles were characterized by (TEM), and particle size analyzer determined the distribution of nanoparticles size. The release performances of 5-FU microspheres in vitro were studied in PH 7.4 phosphate buffered saline. The therapeutic efficacy of 5-FU-loaded PLA microspheres in vivo were studied using MGC-803 (human stomach cancer) xenograft. 32 nude mice were divided into four groups (n =8), 5-FU loaded PLA microspheres were injected at tumor site. VEGF121 monoclonal antibody was connected with 5-FU loaded PLA nanoparticles through carbodimide. The targeted effect of VEGF 5-FU loaded nanoparticles in vivo were observed by single photon emission computed tomography (SPECT) after tail vein injection at 1 h and 2 h. SEM observation showed that microspheres were spherical, and the diameters of two kinds of microspheres were 1 μm and 5 μm respectively. The mean diameter of nanoparticles was 191.0 nm, and the index of polydispersity was 0.202. The drug was released following biphasic kinetics, initial burst and the following steady phase. 1 μm and 5 μm 5-FU-loaded microspheres both resulted in increased life span (1 μm microspheres median survival time=40.63 days, 5 μm microspheres median survival time=62.25 days), against 5-FU pure drug (median survival time=14.5 days). These results strongly suggest that 5-FU-loaded PLA microspheres increase life span of nude mice bearing MGC-803 tumors. After injection for 2 h, almost all the VEGF/5-FU loaded PLA nanoparticles could centralize at the human gastric cancer xenograft sites. That demonstrated VEGF monoclonal antibody remain its bioactivity after connection with nanoparticles, VEGF/5-FU loaded PLA nanoparticles had very exact targeting function for gastric tumor xenograft.

Preparation and Evaluation in Vitro of BCNU-Loaded PLA Nanoparticles

In this study,using a spontaneous emulsification/solvent extraction method,BCNU-loaded PLA nanoparticles (NPs) with small particle size and narrow size distribution have been acquired. The particle size of the NPs ranged from 40~60 nm and 100~200 nm according to different requirements. SEM and TEM showed that the particle size considerably decreases with increasing emulsification concentration and decreasing PLA concentration and ratio of oil to water. The highest drug loading ratio and drug encapsulation efficiency of NPs were 5.63% and 33.45%. The results demonstrated that decrease of initial BCNU content resulted in a noticeably increased encapsulation yield. A thorough study in vitro showed that the drug could be steadily released from NPs for one week. In addition,drug-loaded NPs had higher antitumor activity,compared with free BCNU,and sustained drug release characteristics as well.

Influences of Organic Solvents on Particle Size and Drug-loading Efficiency for 5-Fluorouracil Poly(lactic acid)Nanoparticles

The objective of this study was to investigate the influences of organic solvents on particle size, drug content, loading efficiency and yield for 5 Fluorouracil Poly(lactic acid) nanoparticles . The 5 Fluorouracil was entrapped into poly(lactic acid)(PLA) nanoparticles using a water in oil in water solvent evaporation technique. During the preparation process, ethyl acetate and acetone were used as organic solvents since they are less toxic than the more commonly used dichloromethane. The effect of the three solvents on particle size, drug content, loading efficiency and yield of nanopartcles was compared. When the solvent of the oil phase was acetone, the highest drug content, smallest particle size and lowest yield were obtained for the PLA nanoparticles.