影响胶料中游离硫含量变化关键因素的研究

本文主要介绍利用高效液相色谱法对胶料中游离的可溶性硫含量的测试方法。并模拟混炼与压延生产工艺生产条件,考察影响胶料中游离的可溶性硫含量的关键因素,为实际生产工艺条件的选择与调变提供技术支撑。     

Evaluation of morphology and mechanical properties of austenitic stainless steel 316L exposed to high-velocity liquid PbBi at high temperature

In the accelerator driven sub-critical system(ADS) cooled by liquid PbBi alloy,the austenitic stainless steel 316 L is one of the candidates of structural materials.However,the corrosion and wear behavior of 316 L steel in the high-velocity stream of liquid PbBi is the most essential issue,which is urgent to be paid close attention.In order to acquire the morphology and mechanical properties of 316 L steel in the conditions of different relative flowing velocity(RFV),respectively 2.62 m/s,3.69 m/s,4.77 m/s,the experiment was carried out in dynamic liquid PbBi at 550℃,up to about 1 500 h.According to the results,the surface of 316 L has been corroded badly and the elements of Ni,Cr,etc.were found to dissolve a lot.With the increase of the RFV,the feature of 316 L surface changed from the surface with much deeper pits and looser structures to the relative planar one,and the thickness of the outer oxide layer decreased gradually while that of the inner oxide layer diminished a little,and the microhardness of the outermost substrate also declined increasingly,in addition,the domain of the partial substrate with its microhardness being altered deepened further.These experimental data would offer theoretical basis and practical values to study corrosion condition of 316 L steel in liquid PbBi with high-velocity.     

液膜电化学刻蚀法制备纳米电极的数学模型

介绍了液膜电化学刻蚀法制备纳米电极的原理及过程。根据钨棒刻蚀后的几何形状、电化学反应的基本原理及液体表面张力相关理论,建立了纳米电极制备的数学模型,为液膜电化学刻蚀法制备纳米电极奠定了理论基础。     

Visualization of water drying in porous materials by X‐ray phase contrast imaging

We present in this study results from X‐ray tomographic microscopy with synchrotron radiation performed both in attenuation and phase contrast modes on a limestone sample during two stages of water drying. No contrast agent was used in order to increase the X‐ray attenuation by water. We show that only by using the phase contrast mode it is possible to achieve enough water content change resolution to investigate the drying process at the pore‐scale. We performed 3D image analysis of the time‐differential phase contrast tomogram. We show by the results of such analysis that it is possible to obtain a reliable characterization of the spatial redistribution of water in the resolved pore system in agreement with what expected from the theory of drying in porous media and from measurements performed with other approaches. We thus show the potential of X‐ray phase contrast imaging for pore‐scale investigations of reactive water transport processes which cannot be imaged by adding a contrast agent for exploiting the standard attenuation contrast imaging mode.     

基于Fluent—BP神经网络的液体动静压轴承热特性分析

针对液体动静压轴承运转发热复杂的问题,应用Fluent软件对液体动静压轴承进行CFD仿真分析,获得不同输入状态下的油膜温度场分布以及轴承运转时的平均温度和最高温度。并在此基础上通过正交试验将Fluent仿真与BP神经网络相结合,实现对任意输入参数下轴承工作温度的预测,并对转速与供油压力以及供油压力与供油温度的综合作用效果进行分析。结果表明,主轴转速对轴承作用的效果比较显著,当轴承在高转速状态下运行时,需要提供高的供油压力来保证轴承的正常运转;当供油压力下降和供油温度上升同时出现时,轴承运转温度骤升,必须谨慎对待。利用BP神经网络的泛化功能,以少量的样本,可得到均匀全面的网络训练样本点,从而能快捷有效地实现对液体动静压轴承的热特性分析。     

Analysis of internal crack in a six-ton P91 ingot

P91 is a new kind of heat-resistant and high-tensile steel. It can be extruded after ingot casting and can be widely used for different pipes in power plants. However, due to its mushy freezing characteristics, a lack of feeding in the ingot center often generates many defects, such as porosity and crack. A six-ton P91 ingot was cast and sliced, and a representative part of the longitudinal section was inspected in more detail. The morphology of crack-like defects was examined by X-ray high energy industrial CT and reconstructed by 3D software. There are f ive main portions of defects larger than 200 mm~3, four of which are interconnected. These initiated from continuous liquid f ilm, and then were torn apart by excessive tensile stress within the brittle temperature range(BTR). The 3D FEM analysis of thermo-mechanical simulation was carried out to analyze the formation of porosity and internal crack defects. The results of shrinkage porosity and Niyama values revealed that the center of the ingot suffers from inadequate feeding. Several criteria based on thermal and mechanical models were used to evaluate the susceptibility of hot crack formation. The Clyne and Davies' criterion and Katgerman's criterion successfully predicted the high hot crack susceptibility in the ingot center. Six typical locations in the longitudinal section had been chosen for analysis of the stresses and strains evolution during the BTR. Locations in the defects region showed the highest tensile stresses and relative high strain values, while other locations showed either low tensile stresses or low strain values. In conclusion, hot crack develops only when stress and strain exceed a threshold value at the same time during the BTR.     

封闭玻璃管道内液体折射率的非接触测量

为了实时、原位和非接触测量工业生产过程中封闭管道系统内透明、半透明液体折射率,提出了一种简单的基于玻璃管壁光学特性的液体折射率测量方法。该方法通过涂覆在玻璃管壁外表面上的透射散射层,将入射激光束转换为进入玻璃管壁的大角度分布的透射散射光;透射散射光到达玻璃管壁与液体的界面上后,符合全反射条件的散射光反射到透射散射层上,自动形成与玻璃管内液体折射率值相关的椭圆形暗斑图像。根据椭圆形暗斑长轴长度与液体折射率之间的解析关系,即可实现玻璃管内液体折射率的原位、非接触测量。对几种常见的透明、半透明液体的折射率进行了实验测量,结果表明:该测量方法的准确性与目前商用数字阿贝折射仪相当(±2×10-4 RIU)。该测量方法具有成本低、稳定性好、抗干扰且光源稳定等优点,而且在处理与液体折射率相关的光学图像时无需调试,光照即显,有望用于封闭管道在非常温、非常压状态下液体折射率的实时、自动和非接触在线监测。     

Preparation of novel 2-(2-oxo-2H-chromen-4-yl)-3- arylthiazolidin-4-one derivatives using an efficient ionic liquid catalyst

An eco-friendly procedure for synthesis of 2-(2-oxo-2H-chromen-4-yl)-3-arylthiazolidin-4-one derivatives by three-component reaction of 2-oxo-2H-chromene-4-carbaldehydes, aromatic amines and thioglycolic acid, with tetramethylbutane-1,4-diammonium acetate as a low-cost ionic liquid catalyst under reflux condition is described. The use of an ionic liquid as a catalyst has the advantages of high yields, short reaction time and environmentally friendly reaction media.     

中温时效对17-4PH不锈钢液体氮化后组织性能的影响

目的研究低温盐浴氮化17-4PH不锈钢经中温时效处理后氮化层组织性能的变化情况。方法采用光学显微镜(OM)分析氮化层的厚度和显微组织,利用X射线衍射仪(XRD)检测渗氮层的相组成,利用显微硬度计测定渗层的硬度,利用冲刷腐蚀实验评价渗层的耐腐蚀性能。结果 17-4PH不锈钢氮化后在425~475℃时效保温处理,其渗层厚度随时效时间的延长而增加。时效处理使渗层中N原子的浓度发生改变,过饱和扩展奥氏体发生分解,析出与其结构同为面心立方结构的Fe4N、Fe2N和Cr N。时效温度的升高能加速扩展奥氏体的分解,促进Cr N析出及氧化物的生成。经过渗氮时效后,渗层深度可达27.4μm。根据热力学公式计算出N原子在时效过程中的扩散激活能为216.2 k J/mol,表面显微硬度在初期显著升高,达到了近1150HV0.1,随后逐渐降低。在475℃、50 d的时效条件下,冲刷腐蚀中的失重率达到最大值30.3 mg/(h·dm~2)。结论不锈钢氮化后在一定的温度和时间内时效处理会达到最大表面硬度,在随后的保温过程中硬度开始下降。时效处理后17-4PH不锈钢的耐冲刷腐蚀性能下降。     

Identification of Human UDP-Glucuronosyltransferase 1A4 as the Major Isozyme Responsible for the Glucuronidation of 20(S)-Protopanaxadiol in Human Liver Microsomes

20(S)-protopanaxadiol (PPD), one of the representative aglycones of ginsenosides, has a broad spectrum of pharmacological activities. Although phase I metabolism has been investigated extensively, information regarding phase II metabolism of this compound remains to be elucidated. Here, a glucuronidated metabolite of PPD in human liver microsomes (HLMs) and rat liver microsomes (RLMs) was unambiguously identified as PPD-3-O-β-d-glucuronide by nuclear magnetic resonance spectroscopy and high resolution mass spectrometry. The chemical inhibition and recombinant human UDP-Glucuronosyltransferase (UGT) isoforms assay showed that the PPD glucuronidation was mainly catalyzed by UGT1A4 in HLM, whereas UGT1A3 showed weak catalytic activity. In conclusion, PPD-3-O-β-d-glucuronide was first identified as the principal glucuronidation metabolite of PPD in HLMs, which was catalyzed by UGT1A4.