科创中国

The accurate measurement on the compressibility and thermal expansion coefficients of density standard liquid at 2329kg/m3(DSL-2329) plays an important role in the quality control for silicon single crystal manufacturing. A new method is developed based on hydrostatic suspension principle in order to determine the two coefficients with high measurement accuracy. Two silicon single crystal samples with known density are immersed into a sealed vessel full of DSL-2329. The density of liquid is adjusted with varying liquid temperature and static pressure, so that the hydrostatic suspension of two silicon single crystal samples is achieved. The compression and thermal expansion coefficients are then calculated by using the data of temperature and static pressure at the suspension state. One silicon single crystal sample can be suspended at different state, as long as the liquid temperature and static pressure function linearly according to a certain mathematical relationship. A hydrostatic suspension experimental system is devised with the maximal temperature control error ±50 μK; Silicon single crystal samples can be suspended by adapting the pressure following the PID method. By using the method based on hydrostatic suspension principle, the two key coefficients can be measured at the same time, and measurement precision can be improved due to avoiding the influence of liquid surface tension. This method was further validated experimentally, where the mixture of 1, 2, 3-tribromopropane and 1,2-dibromoethane is used as DSL-2329. The compressibility and thermal expansion coefficients were measured, as 8.5′10–4 K–1 and 5.4′10–10 Pa–1, respectively.

提出一种CPLD和Cortex-M3相配合的视频采集控制系统的设计方法.以ARMv7中的Cortex-M3作为CPLD控制芯片,使用EPM7128作为主控芯片,对视频解码芯片SAA7111A进行视频数据采集,具有适应性和灵活性.介绍一种高效率、低功耗的视频采集控制系统,详细论述了软硬件的设计和实现方案.采用VHDL语言编程的仿真结果表明了该系统在高速下的顺利运行.

This paper shows that a turned trochoidal function disturbance may lead to peripheral drops production. The resulting model is used to describe that a turned trochoidal disturbance leads to peripheral drops production on the liquid jet surface without the necessity for superimposed disturbances. The trochoid is a non-unique parametric function. Only non-unique parametric functions disturbances may lead to peripheral drops production. The trochoidal function disturbance is decomposed to Fourier series. Every Fourier element receives an amplification factor in accordance to the Rayleigh inviscid jet model. Peripheral drops are received on the jet surface. The paper shows that all trochoidal disturbance functions, prolate cycloid, cycloid and curtate cycloid have a capability of peripheral drops producing. A limited capability of peripheral drops production is introduced for the trochoidal curtate cycloid. Produced drops size are reduced for increasing the jet velocity and wave number. Smaller drops are also received by transition from the prolate cycloid to curtate cycloid disturbance.

目的 探讨LASS2/TMSG-1基因沉默对PC-3M-2B4细胞增殖、迁移及侵袭的影响及其作用机制.方法 将实验分为3组:空白对照组(仅转染PBS的PC-3M-2B4细胞)、无关阴性对照siRNA组及LASS2/TMSG-1 siRNA转染组.首先针对LASS2/TMSG-1基因,设计并合成siRNA;在脂质体介导下瞬时转染人前列腺癌PC-3M-2B4细胞24h后分别采用Western blot 和RT-PCR技术检测细胞内LASS2/TMSG-1蛋白及ATP6L mRNA表达水平;使用BCECF AM H+敏感荧光探针检测转染24、36、48、96 h后3组细胞的细胞内H+浓度;用MTT法检测细胞增殖;划痕修复实验和Transwell体外侵袭实验分别检测PC-3M-2B4细胞的迁移和侵袭能力.结果 转染LASS2/TMSG-1 siRNA 24 h后,LASS2/TMSG-1 siRNA组LASS2/TMSG-1蛋白表达与对照组相比下降65%,ATP6L mRNA表达水平与对照组比较提高75%.通过BCECF AM荧光探针检测LASS2/TMSG-1 siR-NA转染组细胞内H+浓度明显下降,且与空白对照组及无关阴性对照siRNA组相比,差异有统计学意义(P<0.05).MTT法检测显示,PC-3M-2B4细胞在转染24、48 h后,3组细胞生长速度无明显差异(P>0.05);转染72 h后LASS2/TMSG-1 siRNA转染组细胞生长速度明显升高,与空白对照组、无关阴性对照siRNA组比较,差异均有统计学意义(P均<0.05).划痕修复试验和Transwell体外侵袭实验显示,转染LASS2/TMSG-1 siRNA 24 h后,与空白对照组及无关阴性对照siRNA组相比,能显著促进细胞迁移和侵袭能力(P<0.05).结论 体外合成的siRNA能有效沉默LASS2/TMSG-1基因表达,同时上调V-ATPase质子泵中关键性亚基—ATP6L mRNA的表达水平,且基因沉默后其细胞内H+浓度下降,提示LASS2/TMSG-1基因可能与ATP6L相互作用、共同参与对细胞内pH值的影响,导致肿瘤细胞内外微环境的改变并影响肿瘤细胞的生物学行为,如增殖、迁移及侵袭能力.

用密度泛函理论对具有分子导线潜在应用前景的线性金属配合物Cr3 (dpa)4Cl2的对称构型1,非对称构型2及其氧化态[ Cr3 (dpa)4Cl2]+3进行理论计算,并结合自然键轨道理论对配合物1~3的Cr-Cr键进行分析.结果表明:(1)中性构型1和2中只形成Cr63++的d2z轨道组成的三中心三电子σ键,α电子由两端向中间的Cr离域,β电子由中间向两端的Cr离域,α电子的离域更显著.由于离域和dpa -配体的螺旋盘绕作用,Cr63+的π轨道中dxz和dyz轨道成份较小且绕金属轴(Z轴)发生不同程度的旋转,难以重叠形成π键.(2)氧化态3中,因配体的螺旋作用,Cr的dxy轨道绕Z轴发生不同程度旋转而无法有效重叠形成δ键,故Cr-Cr短键只存在1个σ键和2个π键的三重键.(3)中性分子的HOMO轨道为σ非键轨道,电子云集中在两端Cr上,两端的Cr(2的长键端的Cr)是失电子形成氧化态3的中心.

等级医院评审标准为医院管理带来了新的理念.为适应评审标准的要求,达到评审的目的,护理部通过解读标准、强化培训、反复自查整改等措施,逐步使各级人员落实标准的意识不断增强,各项工作的落实更加规范,持续质量改进的理念不断强化,逐步形成了按照标准良性运行的有效机制.

基于Ness和Helleseth等人对二元不同周期的m序列之间的互相关函数的研究,研究了不同周期的p元m序列之间的互相关性质,给出了周期为p2 m-1和pm-1的m序列之间的互相关函数所满足的方程,同时证明了当p等于3时,互相关函数至少是3个值的.

The transient behavior of centrifugal pumps during transient operating periods,such as startup and stopping,has drawn more and more attention recently because of urgent needs in engineering.Up to now,almost all the existing studies on this behavior are limited to using water as working fluid.The study on the transient behavior related to solid-liquid two-phase flow has not been seen yet.In order to explore the transient characteristics of a high specific-speed centrifugal pump during startup period delivering the pure water and solid-liquid two-phase flow,the transient flows inside the pump are numerically simulated using the dynamic mesh method.The variable rotational speed and flow rate with time obtained from experiment are best fitted as the function of time,and are written into computational fluid dynamics(CFD)code-FLUENT by using a user defined function.The predicted heads are compared with experimental results when pumping pure water.The results show that the difference in the transient performance during startup period is very obvious between water and solid-liquid two-phase flow during the later stage of startup process.Moreover,the time for the solid-liquid two-phase flow to achieve a stable condition is longer than that for water.The solid-liquid two-phase flow results in a higher impeller shaft power,a larger dynamic reaction force,a more violent fluctuation in pressure and a reduced stable pressure rise comparing with water.The research may be useful to understanding on the transient behavior of a centrifugal pump under a solid-liquid two-phase flow during startup period.

报告1例变形综合征.患者男,42岁,具有偏侧肥大、巨趾、脊柱侧凸、线状表皮痣、淋巴管瘤等变形综合征的表现.文中对该病进行文献回顾性总结及对最新诊断标准进行讨论.

水平衡测试是加强用水科学管理,最大限度地节约用水与合理用水的一项基础工作.解释了水平衡测试的定义及开展测试工作的依据,分析了水平衡测试参数之间关系,介绍了水平衡测试的方法,结合承德市中心医院水平衡测试实例,分析其用水现状,为制定用水定额和计划用水量指标,提供了较准确的基础数据,为今后节约用水提出了合理化的建议.