二甲基硅油的乳化实验

乳化硅油作为消泡剂,在实际的生活生产中有着广泛的应用。在实验的过程中,我们发现硅油的乳化实验受到多种因素的影响,比如各种物质的用量、搅拌的速度等等。     

Magnesium status and the physical performance of volleyball players: effects of magnesium supplementation

Abstract

The aim of this study was to test the hypothesis that magnesium supplementation influences the physical performance of volleyball players, as the efficacy of this approach remains questionable. Twenty-five professional male volleyball players were assigned randomly to experimental (350 mg Mg · d^–1, 4 weeks) and control groups (500 mg maltodextrin · d^–1, 4 weeks) maintaining inter-group homogeneity of urinary magnesium. Erythrocyte, plasma and urinary magnesium levels, plasma creatine kinase activity, lactate production, maximal oxygen uptake (VO₂ max) and plyometric (squat jump, countermovement jump, countermovement jump with arm swing) and isokinetic (peak torque, potency and total work) performances were evaluated before (T₀) and after (T₁) supplementation. Levels of erythrocyte and urinary magnesium and creatine kinase activity and VO₂ max remained within normal ranges in both groups. Plasma magnesium decreased significantly only within the experimental group. Significant decreases in lactate production and significant increases (of up to 3 cm) in countermovement jump and countermovement jump with arm swing values were detected in the experimental group following magnesium supplementation, but not in the control group at T₁. It is concluded that magnesium supplementation improved alactic anaerobic metabolism, even though the players were not magnesium-deficient.     

无水高氯酸镁重量法测定液氯中水含量

随着氯碱企业氯气干燥工艺的改进,设备和下游涉氯产品对水份要求的提高,,大部分氯碱厂液氯含水量都能达到400mg／L以下,有些厂能达到50mg／L以下。无水高氯酸镁是吸水性较强又不和氯气反应的干燥剂,气体通过高氯酸镁的剩余湿度低至O．0002mg／L,吸水后成为三水过氯酸镁,可用于液氯中微量水分的测定。     

碳化法从硼泥中制取轻质碳酸镁转化条件研究

碳化法从硼泥中制取轻质碳酸镁是在催化剂作用下,利用石灰Ca(OH)2和硼泥中的MgCO3经转化反应生成易于碳化的Mg(OH)2,后经碳化、热解等操作制取轻质碳酸镁的一种经济、有效、工艺简单的提镁方法.其中转化反应是影响镁提取率高低的主要因素,文章通过实验讨论了影响转化反应的几个重要因素,确定了最佳转化反应条件.实验表明,镁制取率高,轻质碳酸镁质量符合HG/T2959-1988(1997)的标准要求.     

Mathematical Model and Simulation of Cutting Force in Plunge Milling Process

Plunge milling,also calledZ-axis milling,is one ofthe most effective machining methods in high speed metalremoval machining.Asfor curvedsurface of difficult-to-ma-chine material ,slot-cut working and machining withlongercutter of suspendinglength,the mach…     

轿车轻量化技术发展趋势的研究

轿车轻量化技术的研究一直是汽车行业中的热门话题,也是困扰汽车工业发展的一道难题。如何制造出安全性高,又节能环保的轿车,是整个汽车行业乃至全社会都非常关注的问题。为此,可结合未来汽车轻量化技术,从桥车车身的生产材料、发动机缸体制造方法及运行材料入手,这是汽车行业早日实现高效节能减排的一条捷径。     

镁与心血管疾病

介绍了镁在心脑血管疾病加心律失常、心力衰竭、AMI发病中的作用及镁的每日需要量，并从食物缺镁及生理因素病理因素缺镁等方面探讨了低镁血症的病因。     

Mitigation of Blast Effects on Aluminum Foam Protected Masonry Walls

Terrorist attacks using improvised explosive devices (IED) can result in unreinforced ma-sonry (URM) wall collapse. Protecting URM wall from IED attack is very complicated. An effective solution to mitigate blast effects on URM wall is to retrofit URM walls with metallic foam sheets to absorb blast energy. However, mitigation of blast effects on metallic foam protected URM walls is currently in their infancy in the world. In this paper, numerical models are used to simulate the per-formance of aluminum foam protected URM walls subjected to blast loads. A distinctive model, in which mortar and brick units of masonry are discritized individually, is used to model the perform-ance of masonry and the contact between the masonry and steel face-sheet of aluminum foam is modelled using the interface element model. The aluminum foam is modelled by a nonlinear elas-toplastic material model. The material models for masonry, aluminum foam and interface are then coded into a finite element program LS-DYNA3D to perform the numerical calculations of response and damage of aluminum foam protected URM walls under airblast loads. Discussion is made on the effectiveness of the aluminum foam protected system for URM wall against blast loads.