Isolation, partial characterisation and immunomodulatory activities of polysaccharide from Morchella esculenta

BACKGROUND: Polysaccharides extracted from fungi or algae have shown a variety of medical activities, and the exploitation of polysaccharides for application in pharmacy has been very promising. In this study, the immunomodulatory properties of polysaccharides from Morchella esculenta were investigated to identify immunostimulatory activity and potentially contribute to the therapeutic potential of Morchella esculenta. RESULTS: A water‐soluble polysaccharide, MEP, was obtained from the fermentation broth of Morchella esculenta. Two fractions of this polysaccharide (MEP‐I and MEP‐II) were extracted and purified. High‐performance gel permeation chromatography analysis showed the average molecular weights of two polysaccharides. Structural properties and compositions of these two fractions were examined by Fourier transform infrared and a high‐performance liquid chromatography with an evaporative light scattering detector. Active experiments suggested that the MEP had typical immunostimulatory activity. CONCLUSION: These bioactivity tests showed that the polysaccharides from Morchella esculenta presented significant immune modulating activity, and this finding may offer the basis for the popular use of polysaccharides in functional foods or medicine. Copyright © 2011 Society of Chemical Industry     

用溶聚丁苯橡胶改进轮胎的使用性能

从二十世纪六十年代初以来,溶聚丁苯橡胶已商品化,本文就聚合物特性、工艺性能及硫化性能作了比较,特别是对轮胎使用性能的对比试验作了比较。在同样的结合苯乙烯含量和同样的杨氏模量指数下,对滚动阻力、干湿牵引和磨耗性进行了比较。     

应用过油管防砂技术降低完井费用

很多老井由于原先的完井工艺不合适或储层性质发生变化而导致出砂。对于这些井的二次完井来说，常规的防砂方法和作业设备在经济上往往不可行。应用过油管二次完井方法，通过对完井系统的优化设计，完井费用大幅度下降，同时这种完井方法提高了完井成功率和完井系统的适应性。     

倾斜界面的三维声波波场

三维有限差分法已被用于钻井穿透倾斜层情况下的声波波场的模拟。体积源和点力产生的声波波场可表示成通常的单极和偶极响应，本文主要分析了倾斜层的透射系数和反射系数以及准剪切各向异性。我们发现倾斜层对声波波场的主要影响是使单极和偶极源产生的透射／反射系数产生变化，当偶极源场从松软地层穿过倾斜界面到坚硬地层中时，其透射比穿过水平层时要小得多。ＳＶ波和ＳＨ波穿过倾斜界面时不同透射导致了较大的方位振幅变化，由此     

双主电源并联运行的微电网小信号稳定性分析与控制参数优化北大核心

在基于多主从电源控制的微电网系统中,主电源逆变器的控制参数对系统的稳定性和动态性能有着至关重要的影响。文中以含有两个主电源的双主电源为电网系统为例,首先介绍了系统的控制方式,然后对系统建立了详细的小信号模型,通过计算系统状态矩阵的特征值和参与因子,分析了系统的稳定性和动态性能。在此基础上提出了含有根轨迹法与粒子群算法的控制参数综合优化方案,对逆变器的控制参数进行了协调优化,仿真和实验结果验证了参数优化方案的有效性。     

Single-element ultrasound transducer for combined vessel localization and ablation

This report describes a system that utilizes a single high-intensity focused ultrasound (HIFU) transducer for both the localization and ablation of arteries with internal diameters of 0.5 and 1.3 mm. In vitro and in vivo tests were performed to demonstrate both the imaging and ablation functionalities of this system. For imaging mode, pulsed acoustic waves (3 cycles for in vitro and 10 cycles for in vivo tests, 2 MPa peak pressure) were emitted from the 2-MHz HIFU transducer, and the backscattered ultrasonic signal was collected by the same transducer to calculate Doppler shifts in the target region. The maximum signal amplitude of the Doppler shift was used to determine the location of the target vessel. The operation mode was then switched to the therapeutic mode and vessel occlusion was successfully produced by high-intensity continuous HIFU waves (12 MPa) for 60 s. The system was then switched back to imaging mode for residual flow to determine the need for a second ablation treatment. The new system might be used to target and occlude unwanted vessels such as vasculature around tumors, and to help with tumor destruction.     

Diisopropylammonium chloride: a ferroelectric organic salt with a high phase transition temperature and practical utilization level of spontaneous polarization

A simple organic salt, diisopropylammonium chloride, shows the highest ferroelectric phase transition temperature among molecule-based ferroelectrics with a large spontaneous polarization, making it a candidate for practical technological applications.