Splitless injection of large volumes: Improved carrier gas regulation system

The classical vaporizing injector has been modified for splitless injection of large volumes: during solvent evaporation in the packed vaporizing chamber, the carrier gas supply is interrupted and the septum purge outlet fully opened. This prevents vapors penetrating the gas regulation system and keeps the pressure increase in the injector to a minimum.     

9MeV电子直线加速器X射线测量

 高能工业CT采用9MeV电子加速器产生轫致辐射，利用高能X射线能够有效地穿透物质以及同物质对射线吸收和散射不同这一原理来检查物体内部缺陷或内部结构。加速器电子束的焦点、X射线的最高能量、X射线剂量及均匀性与工业CT成像的质量和速度密切相关；对探测器的电子线路部分进行的X射线屏蔽关系到探测器的使用寿命。X射线测量结果表明，所用9MeV电子直线加速器满足高能工业CT检测的要求。     

一种非矩形平行平板流动腔的定常流分析

高度远小于横向和纵向几何尺寸的平行平板流动腔是当前用以体外研究细胞力学行为的主要工具之一·人们常用的是上下两平行平板是矩形边界的流动腔·这种流动腔内（除入口端和出口端的邻近区域外）的流场是均匀的［１］，因而每次实验只能观测底部培养细胞受一种切应力值的影响情况·本文提出一种上下两平行平板不是矩形的平行平板流动腔·通过对腔内流体作定常流动的流场进行详细分析，给出了流动腔内流速和腔底切应力值的分布·结果发现，利用这种非矩形平行平板流动腔可以同时研究底部培养细胞在多种切应力值下的力学行为·本文理论结果与超声多普勒技术检测流速的实验结果吻合得相当好·     

阳极改性对单室微生物燃料电池性能的影响

构建了老龄垃圾渗滤液为底物的空气阴极型单室微生物燃料电池,以考察阳极不同改性方式对微生物燃料电池产电性能和对老龄垃圾渗滤液处理效果的影响。结果表明,碳毡阳极经过热处理、浓硝酸、酸性重铬酸钾、混酸的改性后,电池的最大输出功率密度分别提高了104%、241%、51%、181%,COD的去除率变化不大,但氨氮去除率分别增加了22.2%、21.8%、2.3%、47.3%。垃圾渗滤液pH值升高、电导率呈下降趋势。     

Fast transient infrared studies in material science: development of a novel low dead-volume, high temperature DRIFTS cell

A prototype DRIFTS flow reaction chamber was designed and developed in order to find analytical application in the study of heterogeneous catalysts operating at high temperatures under fast transient gas feed conditions. Minimisation of dead-volumes allows gas replacement in 8-10 s at 10 mL min⁻¹ total flow. To overcome problems related to the reactivity of the cell walls under alternating oxidizing/reducing gases, the cell was built with Inconel 600™, which was tested to be very inert even at high temperatures. The sample holder, which was developed to closely resemble a micro plug-flow reactor, poses some problems in terms of heat transfer to the outer body of the cell (limiting then the maximum reachable temperature) and of the correct measurement of the actual sample temperature. These problems were solved with a careful re-design of the upper part of the cell. The second prototype thus derived is able to reach temperatures up to 803 K and allows gas replacement in less than 4 s at 10 mL min⁻¹. The cell is inserted in a MCT-FT-IR, which allows to collect high quality spectra with a 1 s time-resolution. The downstream flow can be analysed by a quadrupole mass spectrometer equipped with an enclosed source and by a commercial GC. The performances of this prototype cell are presented showing some tests carried out with ceria-zirconia (Ce_xZr_1−xO₂) catalysts for CO abatement under real operando conditions.     

The MICE facility – a new tool to study plant–soil C cycling with a holistic approach

Plant–soil interactions are recognized to play a crucial role in the ecosystem response to climate change. We developed a facility to disentangle the complex interactions behind the plant–soil C feedback mechanisms. The MICE (‘Multi-Isotope labelling in a Controlled Environment’) facility consists of two climate chambers with independent control of the atmospheric conditions (light, CO₂, temperature, humidity) and the soil environment (temperature, moisture). Each chamber holds 15 plant–soil systems with hermetical separation of the shared above ground (shoots) from the individual belowground compartments (roots, rhizosphere, soil). Stable isotopes (e.g. ¹³C, ¹⁵N, ²H, ¹⁸O) can be added to either compartment and traced within the whole system. The soil CO₂ efflux rate is monitored, and plant material, leached soil water and gas samples are taken frequently. The facility is a powerful tool to improve our mechanistic understanding of plant–soil interactions that drive the C cycle feedback to climate change.     

顶爆和拱腰侧爆同时作用下锚固洞室的动态响应

基于相似模型试验,采用显式非线性动力分析程序LS-DYNA3D研究了地下锚固洞室在拱顶和拱腰侧两处集中装药爆源同时爆炸作用下应力波传播规律、裂纹形成机理以及洞壁围岩位移分布特征。通过对比分析顶爆试验和计算模型的压应力时程曲线,发现模拟与试验结果吻合,且符合应力波的传播规律,表明数值模拟结果可靠。爆源爆炸后,应力波以圆形向周围岩体传播,两应力波相遇处压应力强度明显大于周围岩体;当应力波传到自由面时,会反射形成拉伸波,在地表下方和洞室上方发生“层裂”现象,在拱顶和拱腰侧爆源中间沿洞室径向有裂纹延伸,由于拉伸波的叠加,在爆源下方出现“八”字形的锥形裂纹面。锚杆能够起到加固岩体的作用,锚固洞室比毛洞裂纹分布少,毛洞迎爆侧裂纹主要为横向裂纹,而锚固洞室则为径向劈裂和横向裂纹。两爆源中点洞室径向处的洞壁围岩位移峰值最大,极易产生破坏。     

Determination of the Pressure Dependence of the Shear Viscosity of Polymer Melts Using a Capillary Rheometer with an Attached Counter Pressure Chamber

A capillary rheometer with an attached counter pressure chamber was used to determine the effect of pressure on the shear viscosity of several polymer melts, i.e., poly(?-caprolactam) (PA6), poly(ethylene terephthalate) (PET), low-density polyethylene (LDPE), and polypropylene (PP). In order to study the rheological properties of the polymer melts at a constant pressure, the measured values of shear viscosity were recalculated with respect to a series of pressures by the least square fitting based on the Barus equation. Different calculation methods were used to calculate the pressure coefficients from the recalculated viscosity values. The resulting pressure coefficients of the shear viscosity demonstrated that the degree of the pressure dependence was highest for PP, followed by PET and then LDPE. PA6 exhibited the lowest pressure coefficient.     

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给出了氦冷却固体增殖剂中子学和产氚包层模块(NT-TBM-HCSB)聚变中子诊断的初步设计,提出了用固定或可移动位置微型裂变室探测器和可移动封装薄箔活化分析系统测量中子倍增器之后、固体氚增殖剂中及其后的中子通量;用可移动天然金刚石探测器的紧凑型能谱仪测量中子能谱。此诊断系统可用于中子倍增器的倍增效率,氚增殖层的增殖率与热核实验聚变堆的运行参数、加热和加料方式、磁流体不稳定性、能量约束以及大破裂等离子体参数和状态之间的工程和物理相关关系的实验研究,测量倍增层、氚增殖包层及其后进入屏蔽层的中子通量和能谱,并与MCNP计算相比较,优化和改进中子倍增器、氚增殖包层以及屏蔽层设计,提高氚增殖率。     

化学气相沉积法碳化硅外延设备技术进展

碳化硅(SiC)是制作高温、高频、大功率电子器件的理想电子材料,近20年来随着外延设备和工艺技术水平不断提升,外延膜生长速率和品质逐步提高,碳化硅在新能源汽车、光伏产业、高压输配线和智能电站等领域的应用需求越来越大。与硅半导体产业不同,碳化硅器件必须在外延膜上进行加工,因此碳化硅外延设备在整个产业链中占据承上启下的重要位置,而且也是整个产业链中最复杂、最难开发的设备。本文从碳化硅外延生长机理出发,结合反应室设计和材料科学的发展,介绍了化学气相沉积(CVD)法碳化硅外延设备反应室、加热系统和旋转系统等的技术进展,最后分析了CVD法碳化硅外延设备未来的研究重点和发展方向。