汽车轮胎模板压铸模设计

汽车轮胎花纹各式各样,其成型的质量直接影响汽车的使用性能。轮胎塑胶成型前需要首先加工出轮胎模板。本文就汽车轮胎模板的成型结构工艺性进行分析,并对成型模具进行设计。生产表明,此模具生产效率高,成型工件满足质量要求。     

AZ31B镁合金TIG焊接过程组织分析

以AZ31B镁合金为研究对象,采用光学显微镜分析测试手段,对变形镁合金AZ31B的TIG交流平板对接焊接头进行了微观组织观察,结果发现在熔焊条件下AZ31B镁合金焊缝附近的纤维组织消失,在焊缝区出现了细晶粒,而热影响区(HAZ)的晶粒明显粗大。     

偏最小二乘分光光度法同时测定钙镁

本文研究了在PH10.5的NH_3片-NH_4Cl缓冲溶液存在下,以Ca(或M_g)-酸性铬兰K-OP为体系,用偏最小二乘分光光度法同时测定合成样中的钙镁。在0～6.4×10~(-5)mol/l范围内Ca、Mg均符合Beer定律,结果表明满足微量分析要求。     

硫酸镁对实验性心律失常的防治作用

静注硫酸镁125mg/kg,可拮抗氯化钡及肾上腺素所致麻醉家兔室性心律失常,但对乌头碱引起的大鼠心律失常无拮抗作用。     

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.     

浅析适合高职学生的英语词汇教学

当传统的3P词汇教学模式受到抨击后,新的词汇教学理念纷纷涌现,但高职学生并未因此而从如何记忆词汇的困惑中解放出来。笔者在多年的词汇教学中,通过研究学生课堂学习和自主学习词汇的过程和结果,总结出了一些适合高职学生的词汇教学方法。     

Comparison of hot water immersion at 37.8°C with or without salt for rapid weight loss in mixed martial arts athletes

ABSTRACT

Hot water immersion, known as a hot bath, is used by MMA athletes to produce rapid weight loss (RWL) by means of passive fluid loss. This study investigated the magnitude of body mass losses using a standardized hot bath protocol with or without the addition of salt. In a crossover design, eleven male MMA athletes (28.5 ± 4.6 y; 1.83 ± 0.07 m; 82.5 ± 9.1 kg) performed a 20-min immersion at 37.8°C followed by a 40-min wrap in a warm room. This bath and wrap was performed twice per visit. During one visit, only fresh water was used (FWB), and in the other visit, magnesium sulphate (1.6% wt/vol) was added to the bath (SWB). Prior to each visit, 24 h of carbohydrate, fibre, and fluid restriction was undertaken as part of the RWL protocol. Body mass losses induced by the hot bath protocols were 1.63 ± 0.75 kg and 1.60 ± 0.80 kg for FWB and SWB, respectively, and equivalent to ~2.1% body mass. Under the conditions employed, the magnitude of body mass loss in SWB was similar to FWB. However, further research should explore bathing in a temperature that is consistent with that habitually used by fighters, and/or higher concentrations of salt.     

环保型氢氧化镁阻燃剂的制备研究

氢氧化镁阻燃剂属于无机阻燃剂,具有热稳定性好、无毒、低烟、不产生腐蚀性气体、价格低廉等优点,备受世界各国的青睐。本实验采用氨水法制备氢氧化镁无机阻燃剂,并通过实验讨论了初始反应温度和氨镁摩尔浓度比对反应转化率的影响。实验结果表明：最佳初始温度为20℃,氨镁摩尔浓度比为4：1。     

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.