In-situ TEM observation of the evolution of helium bubbles in Mo during He+ irradiation and post-irradiation annealing

The evolution of helium bubbles in purity Mo was investigated by in-situ transmission electron microscopy (TEM) during 30 keV He⁺ irradiation (at 673 K and 1173 K) and post-irradiation annealing (after 30 keV He⁺ irradiation with the fluence of 5.74×10¹⁶ He⁺/cm² at 673 K). Both He⁺ irradiation and subsequently annealing induced the initiation, aggregation, and growth of helium bubbles. Temperature had a significant effect on the initiation and evolution of helium bubbles. The higher the irradiation temperature was, the larger the bubble size at the same irradiation fluence would be. At 1173 K irradiation, helium bubbles nucleated and grew preferentially at grain boundaries and showed super large size, which would induce the formation of microcracks. At the same time, the geometry of helium bubbles changed from sphericity to polyhedron. The polyhedral bubbles preferred to grow in the shape bounded by {100} planes. After statistical analysis of the characteristic parameters of helium bubbles, the functions between the average size, number density of helium bubbles, swelling rate and irradiation damage were obtained. Meanwhile, an empirical formula for calculating the size of helium bubbles during the annealing was also provided.     

基于微波频差转换的光学拍频研究

光学拍频是大学物理和光学实验教学中的重要内容.由于激光器存在中心波长漂移问题,实验中不易产生可观测的拍频信号.受到微波光子技术中微波波段和光波波段相互作用机理的启发,提出了基于微波频差转换的光学拍频方法.借助强度调制和相位调制将两个频差较小的微波信号调制到同一光载波上,结合光学滤波器获得了两个频差极小的稳定光信号,利用光电探测器实现光学拍频,从仿真和实验两个层面分别获得了可视化的低频拍频信号.该研究为大学物理和光学实验提供了与科学前沿相结合的实验方案,可拓展教学内容和教学深度,有利于培养学生的科学素养.     

Simultaneous Spectrophotometric Determination of Imipramine Hydrochloride with Chlordiazepoxide and Nortriptyline Hydrochloride with Fluphenazine Hydrochloride

Spectrophotometry was used with multivariate calibration to simultaneously determine compounds in mixtures. Two antidepressant mixtures were investigated: imipramine hydrochloride and chlordiazepoxide and nortriptyline hydrochloride and fluphenazine hydrochloride. Considerable spectral overlap and large differences in component concentrations were challenges. Since this type of analysis is often performed using complex algorithms, a simple strategy was used here for the simultaneous determination of both mixture components by classical least squares, principal component regression, and partial least squares. Experimental design was used to select the optimum parameters including the wavelength range, sampling interval, software, and derivative order. Accuracy was enhanced by proper wavelength selection. In addition, derivatives of the raw spectra improved the selectivity. The standard deviation, deviation of mean recovery from 100%, and prediction ability of the models were used as the responses. In respect to these terms, first-order derivatization of the spectra and a sampling interval of 1?nm provided the best results. In particular, the low concentration compounds in the mixtures (chlordiazepoxide and fluphenazine) were determined more accurately with precision lower than 3%. The strategy was used for the quality control of pharmaceuticals containing the mixtures without chemical pretreatment.     

用动光弹性法研究材料引入的分配层对应力波传播的影响

本文用动态光弹性模拟试验分析方法，观察和分析研究了材料不同的分配层对应力波在结构中传播的影响，比较分析了冲击荷载产生的应力波在洞室结构顶部的传播及相互过程，得到指定点处的应力—时间关系曲线，为结构震塌机理的进一步的研究和防护结构的改进提供参考。     

超低间隙钛合金低温动态力学性能

本文利用实验应变模态分析方法，在低温条件下（液氦到室温）研究了航天材料超低间隙钛合金ＴＡ７－Ｄ试样的动态力学性能，使用时域系统识别技术分析了材料在不同温度点的模态参数，并根据基频给出了其动态模量随温度的变化。     

充满水的金属圆柱壳经受轴向撞击时屈曲过程的实验研究

本文报道了五种规格充满水的圆柱壳经受大质量低速度轴向撞击作用时屈曲过程的实验结果。研究表明由于液体的存在，圆柱壳的屈曲模态呈轴对称型的环带波纹，整个撞击过程可以明显地分为振荡的动力加载、平稳发展的后屈曲和迅速下降的弹性卸载三个阶段。并讨论了试件壁厚和高度等几何参数对其屈曲性能的影响。     

A microfluidic membrane chip for in situ fouling characterization

A new method for non-invasive in situ monitoring of a microfiltration process is described. In microfiltration systems, local information on the deposition characteristics can be used to determine the cake behavior during a filtration run. Typically, non-invasive methods of fouling study are restricted to specialized membranes, or require highly complex systems. This study employs the use of synthetic embedded channel membranes, with channels separated by a porous structure (active membrane). The characteristics of the active membrane have been analyzed. Deposition on the membrane surface can be observed and monitored optically across the width of the feed channel. This can be used to observe the liquid hydrodynamics in the channel as well as the local cake properties in time. In dead end filtration, it has been observed that with 6 μm particles, the cake initially deposits towards the end of the membrane. However, as filtration continues, the deposition changes with more local deposition towards the channel entrance, leading to a more homogeneous cake layer.     

Computational performance and cross‐validation error precision of five PLS algorithms using designed and real data sets

An evaluation of computational performance and precision regarding the cross‐validation error of five partial least squares (PLS) algorithms (NIPALS, modified NIPALS, Kernel, SIMPLS and bidiagonal PLS), available and widely used in the literature, is presented. When dealing with large data sets, computational time is an important issue, mainly in cross‐validation and variable selection. In the present paper, the PLS algorithms are compared in terms of the run time and the relative error in the precision obtained when performing leave‐one‐out cross‐validation using simulated and real data sets. The simulated data sets were investigated through factorial and Latin square experimental designs. The evaluations were based on the number of rows, the number of columns and the number of latent variables. With respect to their performance, the results for both simulated and real data sets have shown that the differences in run time are statistically different. PLS bidiagonal is the fastest algorithm, followed by Kernel and SIMPLS. Regarding cross‐validation error, all algorithms showed similar results. However, in some situations as, for example, when many latent variables were in question, discrepancies were observed, especially with respect to SIMPLS. Copyright © 2010 John Wiley & Sons, Ltd.     

Sulfuretin protects against cytokine-induced ��-cell damage and prevents streptozotocin-induced diabetes

NF-κB activation has been implicated as a key signaling mechanism for pancreatic β-cell damage. Sulfuretin is one of the main flavonoids produced by Rhus verniciflua, which is reported to inhibit the inflammatory response by suppressing the NF-κB pathway. Therefore, we isolated sulfuretin from Rhus verniciflua and evaluated if sulfuretin could inhibit cytokine- or streptozotocin-induced β-cell damage. Rat insulinoma RINm5F cells and isolated rat islets were treated with IL-1β and IFN-γ to induce cytotoxicity. Incubation of cells and islets with sulfuretin resulted in a significant reduction of cytokine-induced NF-κB activation and its downstream events, iNOS expression, and nitric oxide production. The cytotoxic effects of cytokines were completely abolished when cells or islets were pretreated with sulfuretin. The protective effect of sulfuretin was further demonstrated by normal insulin secretion of cytokine-treated islets in response to glucose. Treatment of mice with streptozotocin resulted in hyperglycemia and hypoinsulinemia, which was further evidenced by immunohistochemical staining of islets. However, the diabetogenic effects of streptozotocin were completely prevented when mice were pretreated with sulfuretin. The anti-diabetogenic effects of sulfuretin were also mediated by suppression of NF-κB activation. Collectively, these results indicate that sulfuretin may have therapeutic value in preventing β-cell damage.