Effect of ligand passivation on morphology,optical and photoresponse properties of CdS colloidal quantum dots thin film

In the present report, cadmium sulfide (CdS) colloidal quantum dots (CQDs) with average diameter of 6 nm were synthesized by using oleylamine as ligand and solvent. The insulating oleylamine ligands form barriers around the CdS CQDs to decrease carrier mobility. In order to remove the ligands and improve the photoelectrical properties of the closed-packed film, ethanedithiol, mercaptopropionic acid and cetyltrimethylammonium bromide (CTAB) were applied for solid state ligand exchange. CTAB treated film had the fastest 3 dB bandwidth of 144.7 Hz and yielded the highest detectivity of 1.37 × 10⁸ Jones. The excellent properties of ligand passivation have important application in nanocrystals based electronic and optoelectronic devices.     

主动磁悬浮轴承支承旋转机械的减振性能研究

针对旋转机械的振动噪声问题,在对轴承工作特性及系统振动传递特性进行理论分析的基础上,提出了采用新型主动磁悬浮轴承取代传统机械轴承以实现整机减振降噪的设想.以某工程试验样机为研究对象,利用有限元软件考察了轴承的刚度变化对该样机轴承座机脚振动不平衡响应的影响,进而开展了专门的振动对比实验来对主动磁悬浮轴承的减振性能进行实际评估.结果表明:减小轴承刚度的思路对于降低旋转机械的机脚振动确实可行;相比于机械轴承,采用主动磁悬浮轴承支承对于减小整机振动水平具有显著实际效果.相关结论可为拓展主动磁悬浮轴承技术的应用领域和场合提供重要思路及数据支持,同时也为其今后的工程化实用奠定研究基础.     

Comparison of the effects of Mg–6Zn and titanium on intestinal tract in vivo

To evaluate the ability of Mg–6Zn to replace titanium nails in the reconstruction of the intestinal tract in general surgery, we compared the Mg–6Zn and titanium implants with respect to their effects on rat’s intestinal tract by biochemical, radiological, pathological and immunohistochemical methods. The results indicated that Mg–6Zn implants started to degrade at the third week and disintegrate at the fourth week. No bubbles appeared, which may be associated with intestinal absorption of the Mg–6Zn implants. Pathological analyses (containing liver, kidney and cecum tissues) and biochemical measurements, including serum magnesium, creatinine, blood urea nitrogen, glutamic–pyruvic–transaminase and glutamic–oxaloacetic–transaminase proved that degradation of Mg–6Zn did not harm the important organs, which is an improvement over titanium implants. Immunohistochemical results showed that Mg–6Zn could enhance the expression of transforming growth factor-β₁. Mg–6Zn reduced the expression of tumor necrosis factor at different stages. In general, our study demonstrates that the Mg–6Zn alloy had good biocompatibility in vivo and performed better than titanium at promoting healing and reducing inflammation. It may be a promising candidate for stapler pins in intestinal reconstruction.     

Theoretical analysis of long-lived radioactive waste in pressurized water reactor

Background The accelerator-driven subcritical transmuta-tion system(ADS)is an advanced technology for the harmless disposal of nuclear waste.A theoretical analy...     

数码相机面壳注射成型的浇口优化设计

通过运用Moldnow软件对数码相机面壳注射成型进行了流动模拟分析,预测在不同浇口位置和数目的情况下可能存在的气泡和熔接痕位置,确定了最佳的浇口数目和位置.     

Two-dimensional MX Dirac materials and quantum spin Hall insulators with tunable electronic and topological properties

We propose a novel class of two-dimensional(2D)Dirac materials in the MX family(M=Be,Mg,Zn and Cd,X=Cl,Br and I),which exhibit graphene-like band structures with linearly-dispersing Dirac-cone states over large energy scales(0.8–1.8 eV)and ultra-high Fermi velocities comparable to graphene.Spin-orbit coupling opens sizable topological band gaps so that these compounds can be effectively classified as quantum spin Hall insulators.The electronic and topological properties are found to be highly tunable and amenable to modulation via anion-layer substitution and vertical electric field.Electronic structures of several members of the family are shown to host a Van-Hove singularity(VHS)close to the energy of the Dirac node.The enhanced density-of-states associated with these VHSs could provide a mechanism for inducing topological superconductivity.The presence of sizable band gaps,ultra-high carrier mobilities,and small effective masses makes the MX family promising for electronics and spintronics applications.     

基于“双芯”51内核的学习机设计

嵌入式系统在教育领域的应用产生了各种类型的学习机,重点论述了一种基于M CS-51内核的“双芯”的嵌入式学习机系统,满足了职业学校学生录入练习的需求。通过对这个系统的分析和论述提出一种在51内核上运行复杂系统的方法。     

Mathematical modeling in the geoinformation problem of the dynamics of geomigration under space–time nonlocality

A mathematical model is set up to analyze the dynamics of locally time- and space-nonequilibrium migration–consolidation processes in a porous earth saturated with salt solutions under mass transfer. The corresponding nonlinear boundary-value problem is stated, an algorithm of its approximate solution is presented, and the results of the numerical implementation of the algorithm are given.