Calcium antagonistic effects of Bambusa Rigida investigated by Ca and its protection on myocardial ischemia of rats

An investigation was conducted using 45Ca as a radioactive tracer to evaluate calcium antagonistic effects of several extracts from Bambusa Rigida in living rats. The relationship between the flavonoid and saccharide contents of Bambusa Rigida and calcium antagonistic effects were also analyzed. The protective effects of the alkali extracts ofBambusa Rigida on myocardial ischemia were investigated in living rats. The results indicated that the alkali extracts of Bambusa Rigida had a prominent influence on Ca2 influx and efflux in the isolated rat aorta and heart, as they could obviously block 45Ca entering into cells and stimulate efflux of intracellular Ca2 . Moreover, the alkali extracts of Bambusa Rigida had favorable protective effects on myocardial ischemia induced either by isoproterenol injection (ISO) or by the ligation of coronary artery. These results implied that the Bambusa Rigida had attractive potential for the treatment of heart, cerebrovascular and other diseases. However, the conclusion that whether the flavonoid or saccharide in Bambusa Rigida affected the calcium antagonistic effects and Ca2 channels or not was hard to make within the results of the investigation.     

麦草浆黑液燃烧系统的运行经验

在碱回收建成投产的几年中,中牟纸厂把大部分精力都投在燃烧炉方面,由于炉子结构不能适应麦草浆黑液的特点,故障接连发生。多年来的生产实践表明:草浆黑液在工艺操作、设备选型等方面都应该和木浆黑液有所区别。１文丘里系统的运行在投产的前期,我们一直采用的是间断进液大循环操作,这种办法在炉子生产不正常的情况下,为稳定黑液浓度,以利操作稳定起过积极作用。随着炉子生产的稳定,大循环浓缩黑液的办法已显得落后和麻烦,它的动力消耗大,工人操作劳动强度大。现改为小循环浓缩黑液,其流程为:为了稳定文丘里系统的生产,我们在旋风分离器、大…     

基于ANSYS的交流接触器电磁机构的三维有限元分析

本文以CJ20-25型交流接触器为例,借助大型有限元分析软件ANSYS,对其双E型电磁机构建立了三维有限元模型,得到了磁场分布图,完成了动态吸力特性和磁链的计算,并将结果与实测数据进行了比较和分析。     

Improved toughness and electromagnetic shielding-effectiveness for graphite-doped SiC ceramics with a net-like structure

The graphite-doped SiC ceramics with net-like structure was fabricated via tape casting and pressureless sintering. The ceramics exhibited a step-like fracture mode, which could be attributed to the net-like structure composed of long columnar SiC grains, layered graphite, and the three-modal pore distribution. The formation of warped epitaxial graphene and large size graphite could be attributed to the pyrolysis of organics in the tape casting system. In the net-like structure, the SiC grains provide the high strength, whereas the layered graphite and three-modal pores were used to deflect the cracks and release the stress at the tip, following the crack-tip-shielding mechanism. The sample with a net-like structure exhibited a combination of a variety of extrinsic toughening mechanisms, such as crack deflection, crack bridging, crack branching and delamination, pull-out, and rupture of layered graphite, which led to improved fracture toughness of 7?MPa?m^1/2, flexural strength of 400?MPa, and (work of fracture) WOF of 3.3?kJ?m^?2. When increasing the graphite content, the electrical conductivity of the graphite-doped SiC ceramics significantly increased from 7.15?×?10^?4 to 216 S/m. The high shielding effectiveness of 34.1?dB was due to the multi-absorption on the various surfaces during the multi-reflection by the net-like structure.     

1Cr13型马氏体不锈钢化学成分与淬火温度区间关系的研究

基于Jmat-Pro软件对合金元素含量不同的1Cr13马氏体不锈钢进行了组织模拟,得到了5种不同合金元素对铁素体转变温度的影响规律。同时,综合5种不同合金元素的作用,利用MATLAB多元线性回归拟合建立了1Cr13马氏体不锈钢合金含量与淬火温度的关系模型。     

Tribological Properties of Short Fiber C/SiC Brake Materials and 30CrSiMoVA Mate

In this study, the short fiber C/SiC brake materials were prepared by a combined process of the fibers dipped with resin, chopping, warm pressing, pyrolyzing, and the liquid silicon infiltration process. The tribological properties of short fiber C/SiC brake materials and 30CrSiMoVA mate were investigated. The results indicated that the average friction coefficient decreased with the increase of braking speed (initial braking speed), and the friction coefficient tended to be constant when the braking speed was higher than 20 m/s. The braking was stable when the braking speed was 5 m/s, and the braking was unstable when the braking speed was higher than 10 m/s. The wear rate of the C/SiC increased with the increase of braking speed when the braking speed was less than 10 m/s, decreased with the increase of braking speed when the braking speed was less than 20 m/s, and then increased afterward with the increase of braking speed. When the braking speed was higher than 20 m/s, an oxidation-abrasion mechanism could occur. With braking speed increasing, the number of the ribbon debris increased, and the ribbon debris got long and thick, and the number of big granular debris increased.     

Simulated three-dimensional transient temperature field during aircraft braking for C/SiC composite brake disc

In the present work, a theoretical model of three-dimensional transient temperature field for C/SiC composite brake discs was established by adopting a finite element method according to the theory of energy transformation and transportation. The variation regularities of transient temperature field and internal temperature gradient of the brake discs were obtained. The effects of initial velocity, deceleration and friction coefficient on the highest temperature of the brake discs were also discussed. The heat energy was mainly concentrated on the layer of friction surfaces. The highest temperature of the brake discs under normal landing, overload landing, and rejected take-off landing condition were 869.7 K, 1037.4 K and 1440.3 K, respectively. Furthermore, the highest temperature of the brake discs increased with the increase of the initial velocity and friction coefficient, but decreased with the increase of deceleration. Comparing simulation predictions with experimental results, it is found that the three-dimensional transient temperature field model was valid and reasonable.     

FEM网格对圆钢温度场计算结果的影响

采用３种不同网格划分，用有限元方法对圆钢待轧过程温度场进行了解析，结果表明，采用均匀网格所解出的温度分布曲线亦匀称光滑，反之，若相邻网格的尺寸相差过大或畸形，则解出的温度场将在相应的局部出现反常的温度波动。     

三维数值解析技术在轧制中的应用现状与展望

介绍了以有限元为代表的三维数值解析技术在轧制过程解析中的应用情况与展望。     

热带粗轧机组宽度变化规律的实验研究

采用铅作为模拟材料，对热带粗轧机组平辊立轧及随后水平轧制时轧件宽度变化规律进行了实验研究。分析和比较了宽展行为及头、尾部失宽行为与变形工艺参数之间的关系，并得到了相应的数学模型。