Particle-surface interaction in thin vitrified films for cryo-electron microscopy

The concentration of particles in thin vitrified films of suspensions is described as a function of various parameters such as the type of particles observed, the time the sample is left on the grid and the effect of different washing procedures. The thin films are prepared for cryo-electron microscopy by the classical, single-side blotting method or by blotting both sides of the grid simultaneously. The two-side blotting method gives the most faithful representation of the bulk solution. The single-side blotting method results in particles preferentially adsorbing to the non-blotted surface. This has the advantage that the concentration of particles in the thin vitrified film is higher than in the original suspension. The energy involved in adhesion of particles to the surface seems to be generally small. In most cases, it does not cause significant deformation of the particles or of the surface of the film. However, there are cases, as for example with lipid vesicles, where the particles are broken as a result of adsorption. Since particles remain adsorbed to the air-liquid interface, it is possible to wash or dialyse the solution directly on the grid with negligible loss of particles. This represents a very rapid and handy method for micro-dialysis. A thin film is then formed by blotting the specimen and vitrified by rapid cooling.     

场景视点偏移的激光雷达点云分割

目的 激光雷达采集的室外场景点云数据规模庞大且包含丰富的空间结构细节信息,但是目前多数点云分割方法并不能很好地平衡结构细节信息的提取和计算量之间的关系。一些方法将点云变换到多视图或体素化网格等稠密表示形式进行处理,虽然极大地减少了计算量,但却忽略了由激光雷达成像特点以及点云变换引起的信息丢失和遮挡问题,导致分割性能降低,尤其是在小样本数据以及行人和骑行者等小物体场景中。针对投影过程中的空间细节信息丢失问题,根据人类观察机制提出了一种场景视点偏移方法,以改善三维（3D）激光雷达点云分割结果。方法 利用球面投影将3D点云转换为2维（2D）球面正视图（spherical front view,SFV）。水平移动SFV的原始视点以生成多视点序列,解决点云变换引起的信息丢失和遮挡的问题。考虑到多视图序列中的冗余,利用卷积神经网络（convolutional neural networks,CNN）构建场景视点偏移预测模块来预测最佳场景视点偏移。结果 添加场景视点偏移模块后,在小样本数据集中,行人和骑行者分割结果改善相对明显,行人和骑行者（不同偏移距离下）的交叉比相较于原方法最高提升6.5%和15.5%。添加场景视点偏移模块和偏移预测模块后,各类别的交叉比提高1.6% 3%。在公用数据集KITTI（Karlsruhe Institute of Technology and Toyota Technological Institute）上与其他算法相比,行人和骑行者的分割结果取得了较大提升,其中行人交叉比最高提升9.1%。结论 本文提出的结合人类观察机制和激光雷达点云成像特点的场景视点偏移与偏移预测方法易于适配不同的点云分割方法,使得点云分割结果更加准确。     

DNA表达载体构建及HIV多表位核酸疫苗的设计与表达

目的利用塞姆利基森林病毒(SFV)复制子构建新型真核表达载体,并对含HIV-1中国流行株B亚型核心蛋白p24及多表位MEG嵌合基因的核酸疫苗进行表达与鉴定。方法将含SFV复制子的元件从pSFV-MCS中切下,连入含CMV启动子及增强子的pIRESneo载体中,构建新型真核表达载体pCS,再将含HIV-1 MEGp24基因插入至pCS载体中,构建重组核酸疫苗pCS-MEGp24。用脂质体法将重组质粒转染入BHK-21细胞,进行表达产物的检测。结果间接免疫荧光检测显示,重组质粒转染的BHK-21细胞能有效表达HIV-1 MEGp24,并与HIV阳性血清反应。结论所构建的核酸疫苗可在BHK-21细胞系内进行表达,且MEGp24基因的表达蛋白具有特异性,为构建新型HIV-1中国流行株核酸疫苗的可行性提供了重要实验依据。     

Virtualizing Network and Service Functions： Impact on ICT Transformation and Standardization

Virtualization of network/service functions means time sharing network/service（and affiliated）resources in a hyper speed manner.The concept of time sharing was popularized in the 1970s with mainframe computing.The same concept has recently resurfaced under the guise of cloud computing and virtualized computing.Although cloud computing was originally used in IT for server virtualization,the ICT industry is taking a new look at virtualization.This paradigm shift is shaking up the computing,storage,networking,and ser vice industries.The hope is that virtualizing and automating configuration and service management/orchestration will save both capes and opex for network transformation.A complimentary trend is the separation（over an open interface）of control and transmission.This is commonly referred to as software defined networking（SDN）.This paper reviews trends in network/service functions,efforts to standardize these functions,and required management and orchestration.     

Nanotechnology in castable refractory

In recent times nanotechnology has drawn significant attention in the field of refractory research. Different nano-powders and colloidal suspensions have been utilized to improve the properties of refractory castables. Various studies have been carried out worldwide with nano scaled binders; such as, hydratable alumina (HA), colloidal alumina (CA), colloidal silica (CS), micro silica, etc.; to improve the thermo mechanical properties of refractory materials. Nano scaled additives are also being applied to reduce the energy consumption and to improve the densification process at lower temperatures. In this paper, the contributions of nanotechnology in selection of raw materials, the binders and choice of additives to improve the quality of refractory materials, and the future of nanotechnology in refractory research are reviewed.