Theoretical Prediction of Chiral 3D Hybrid Organic–Inorganic Perovskites

Hybrid organic–inorganic perovskites (HOIPs), in particular 3D HOIPs, have demonstrated remarkable properties, including ultralong charge‐carrier diffusion lengths, high dielectric constants, low trap densities, tunable absorption and emission wavelengths, strong spin–orbit coupling, and large Rashba splitting. These superior properties have generated intensive research interest in HOIPs for high‐performance optoelectronics and spintronics. Here, 3D hybrid organic–inorganic perovskites that implant chirality through introducing the chiral methylammonium cation are demonstrated. Based on structural optimization, phonon spectra, formation energy, and ab initio molecular dynamics simulations, it is found that the chirality of the chiral cations can be successfully transferred to the framework of 3D HOIPs, and the resulting 3D chiral HOIPs are both kinetically and thermodynamically stable. Combining chirality with the impressive optical, electrical, and spintronic properties of 3D perovskites, 3D chiral perovskites is of great interest in the fields of piezoelectricity, pyroelectricity, ferroelectricity, topological quantum engineering, circularly polarized optoelectronics, and spintronics.     

浅论基于局域网的计算机机房管理维护

随着计算机技术的不断迅猛发展,现在的计算机机房面对大量的计算机设备,传统的管理维护方法已不能胜任,必须充分利用局域网的特性,大量采用新技术,新手段,新软件的辅助,批量的管理维护,提高效率,让计算机设备更好地为人们服务。本文就通过笔者的一些经验来讲述了对于局域网的计算机机房管理维护的一些基本方法。     

“水量平衡分析”的露天煤矿水资源综合利用途径

为有效解决我国北方矿区煤-水资源逆向分布和矿井水回用率低等问题，以神华某露天煤矿为例，基于“水量平衡分析”的方法，提出了水资源综合利用途径。通过分析矿区水资源利用现状与存在的问题，重点探讨矿坑污水处理厂水量变化规律，重构矿区水量平衡图，最终确定矿区水资源综合利用途径。结果表明：1）近三年矿坑涌水量、污水厂处理水量和回用水量均逐年降低，水资源利用率低；2）基于矿区污水处理厂处理水量变化分析，发现该矿区2016年到2018年的矿坑污水量主要受季节的影响较大；3）该矿区水资源在不同季节的回用方向和回用量也不同；4）综合考虑了时间和空间因素，确定了水资源综合利用技术，结合矿区实际用水需求，重构了水量平衡图，将采暖季与非采暖季的矿坑水资源利用率提高到89.9%与70.1%，促进了矿区的可持续发展，最终可实现煤-水资源的和谐共生。     

A novel design for stable self-assembly cubosome precursor-microparticles enhancing dissolution of insoluble drugs

Cubosomes have been presented to enhance dissolution of insoluble drugs, but their applications are limited by the practical hurdles associated with both preparation and storage instability, resulting in drug delivery failure. In the present study, an innovative cubosome precursor-microparticles (CPMs) spray dried from an aqua-free precursor solution was developed to improve cubosome stability during both preparation and storage as well as to enhance the dissolution of insoluble drugs. These CPMs spontaneously self-assembled in situ forming homogeneous cubosome dispersion by hydration and disintegration after exposure to the aqueous medium. The stable cubosome dispersion was obtained from self-assembly (SA) of CPMs after administration instead of fragmentation of bulk cubic phase gel into cubosomes, which settled the preparation instability due to avoidance of high energy fragmentation (e.g. ultrasonic effect, high speed shear and high pressure homogenization). Also, the subsequent storage instability issue can be excluded as the CPMs were stored in a solid stable form. The CPMs disintegration and cubosome SA were demonstrated by the notable morphology variation and the distinct microparticle size decrease from CPMs (10–20?μm) to SA-cubosomes (150–200?nm). The cumulative release of docetaxel (DTX, model insoluble drug) incorporated in CPMs increased to 96.4% within 120?minutes compared with only 75.2% for blank CPMs and DTX physical mixture, demonstrating that CPMs significantly enhanced the dissolution extent of insoluble drug. The SA-cubosomes possessed quite high drug entrapment efficiency (>95%) and an integrated drug dissolution content, which significantly increased the drug utilization rate.     

Effect of Ti3SiC2 Content on Tribological Behavior of Ni3Al Matrix Self-Lubricating Composites from 25 to 800 °C

The self-lubricating composites of Ni₃Al-Ti₃SiC₂-TiC-C (NMC) with varying Ti₃SiC₂ contents were fabricated by spark plasma sintering technique. Dry sliding pin-on-disc friction and wear tests of NMC against Si₃N₄ ceramic ball were undertaken at 25, 200, 400, 600, and 800 °C in air, respectively. The results showed that NMC with 15 wt.% Ti₃SiC₂ lubricant owned the excellent tribological properties over a wide temperature range from 25 to 800 °C, whose friction coefficients and wear rates were about 0.17-0.58 and 0.31-4.2 × 10^?5 mm³/N/m, respectively. A possible explanation for these results was that the subsurface microstructure self-refinement and the special stratification morphology of the tribo-layer were beneficial to the reduction of friction coefficient. Meanwhile, the protective action of the tribo-layer for the frictional surface could also decrease the wear rate.     

台风强度变化最快时涡度的解析解

利用旋转坐标系中的基本方程推导得到动能方程,通过动能的局地变化率定义刻画台风强度变化率的能量泛函,对泛函作变分得到Euler-Lagrange方程.分析方程可知,当台风强度变化率达到最大时,摩擦力、气压梯度力、重力和动能梯度满足四力平衡关系.因此,这四个力确定的向量可以作为台风强度的预报因子,更准确地确定台风系统强度变化率达到最大的时间点.进一步通过风场变分分解提取到有旋场中的最大涡旋,得到台风强度变化最快时涡度和流场的解析解,对研究台风发展过程中速度的变化趋势和台风的空间结构具有实用价值,为台风路径和强度预报提供了一定的理论指引.     

用密闭补偿技术提高固井质量

为解决江苏油田调整井固并质量差问题，使用了密闭补偿技术，即使用ＴＷＦ１４０─Ⅱ型水力式封隔器，限制水泥浆纵向膨胀；使用ＹＸ—１型发气水泥浆膨胀剂，补偿水泥浆凝结过程中的收缩。该项技术的应用大幅度提高了国井质量。文中阐述了该项技术的基本原理及应用方法，提出了进一步完善该项技术的几点建议。     

提取鼠肠道内微生物基因组DNA的方法研究

通过改进鼠肠道微生物基因组DNA提取方法以期更全面地反映鼠肠道茵群的真实情况.采用CTAB和SDS结合的方法裂解细胞,同时改进了传统的酚/氯仿抽提方法,提取全过程控制在2 h以内.通过紫外分光光度计,细菌通用引物PCR,总菌群实时定量PCR,变性梯度凝胶电泳(DGGE)对改进方法及两种试剂盒法提取DNA的结果进行比较,评价了所建立的高效提取方法.与试剂盒相比,改进的方法DNA得率较高,简便快速,成本低廉.同时后续的PCR鉴定及DGGE菌群多样性分析显示,改进的方法可以更好地揭示鼠肠道菌群分布和特性.     

基于MMA7260和μPD78F0547的水泵振动信号采集器

基于单片机μPD78F0547和加速度传感器MMA7260的水泵振动信号采集器的设计。该振动信号采集器可以实现对水泵振动信号的实时采集,并能通过RS232接口将振动数据传送到上位机,具有高灵敏度、高速、低成本、方便和实用等优点。以水泵正常运行和发生支座松动、不对中故障为例,进行水泵振动信号采集与小波消噪处理实验。实验表明该振动信号采集器可以很好地获取水泵各种工况下的振动信号。