香菇中麦角甾醇生成维生素D_2的光化反应实验设计

蘑菇中的麦角甾固醇经紫外线照射后可产生维生素D2,能被人体吸收利用,是天然维生素D的重要来源之一。为了增进本科生对脂溶性维生素代谢的认识和理解,设计了从香菇中提取麦角甾醇,再经光化反应将麦角甾醇转化为维生素D2的生物化学教学实验。为简化实验步骤、方便教学,试验筛选出了样品预处理、光反应及热反应的最佳条件,确定了不经皂化处理,提取物先后用254、365 nm的紫外光照射1 h后,置于85℃水浴下处理15 min实验流程。经高效液相色谱分析,测得产物收率为4.5%。     

（NH4）2S2O8和KI反应级数测定实验的改进

对（NH4）2S2O8和K1反应级数测定的失败原因进行了分析,主要为长期存放的（NH4）2S2O8试剂部分变质,可以通过添加适量的Na2SO3,除去过硫酸铵（NH4）2S2O8分解产生的活性氧化物质,处理后的（NH4）2S2O8溶液用于反应级数测定实验,可以获得反应物浓度与反应速率的良好线性关系,同时优化了本实验测速剂Na2S2O3在不同室温下的“842”比例方案,改善了实验教学效果。     

置换法测金属原子量实验的微型化

对置换法测金属原子量实验进行了微型化研究,改进了实验装置,实现了药品的微量化．与常量制备的方法相比较,具有节约药品、省时、装置简便、操作安全快速等优点．     

磁约束核聚变环境中流道插件的热变形分析

对国际热核聚变实验堆的双冷锂铅包层进行流固共轭传热的三维数值模拟,计算两端不同约束下流道插件FCI结构的热变形和热应力分布,分析对流换热系数和热导率对FCI结构热变形和热应力的影响规律.结果表明,若钢壁与外界的对流换热系数增大,则FCI温度降低,导致热变形和热应力减小;高热导率的FCI材料将使得FCI沿厚度方向温度梯度减小,导致结构的热应力减小.     

Novel mathematical model to estimate ball impact force in soccer

To assess ball impact force during soccer kicking is important to quantify from both performance and chronic injury prevention perspectives. We aimed to verify the appropriateness of previous models used to estimate ball impact force and to propose an improved model to better capture the time history of ball impact force. A soccer ball was fired directly onto a force platform (10 kHz) at five realistic kicking ball velocities and ball behaviour was captured by a high-speed camera (5,000 Hz). The time history of ball impact force was estimated using three existing models and two new models. A new mathematical model that took into account a rapid change in ball surface area and heterogeneous ball deformation showed a distinctive advantage to estimate the peak forces and its occurrence times and to reproduce time history of ball impact forces more precisely, thereby reinforcing the possible mechanics of ‘footballer’s ankle’. Ball impact time was also systematically shortened when ball velocity increases in contrast to practical understanding for producing faster ball velocity, however, the aspect of ball contact time must be considered carefully from practical point of view.     

Effects of timing of signal indicating jump directions on knee biomechanics in jump-landing-jump tasks

A variety of the available time to react (ATR) has been utilised to study knee biomechanics during reactive jump-landing tasks. The purpose was to quantify knee kinematics and kinetics during a jump-land-jump task of three possible directions as the ATR was reduced. Thirty-four recreational athletes performed 45 trials of a jump-land-jump task, during which the direction of the second jump (lateral, medial or vertical) was indicated before they initiated the first jump, the instant they initiated the first jump, 300 ms before landing, 150 ms before landing or at the instant of landing. Knee joint angles and moments close to the instant of landing were significantly different when the ATR was equal to or more than 300 ms before landing, but became similar when the ATR was 150 ms or 0 ms before landing. As the ATR was decreased, knee moments decreased for the medial jump direction, but increased for the lateral jump direction. When the ATR is shorter than an individual’s reaction time, the movement pattern cannot be pre-planned before landing. Knee biomechanics are dependent on the timing of the signal and the subsequent jump direction. Precise control of timing and screening athletes with low ATR are suggested.     

Effect of 6-weeks WBVT on the behaviour of the lower limb muscle fibres during vertical jumping

The purpose of the current study was to examine the effect of 6 weeks of whole body vibration training (WBVT) on body composition, muscle activity of the gastrocnemius and vastus lateralis, gastrocnemius muscle architecture (static and dynamic) and ground reaction forces (performance jump) during the take-off phase of a countermovement jump in young healthy adult males. A total of 33 men (23.31 ± 5.62 years) were randomly assigned to a whole body vibration group (experimental group, EG_WBVT: n = 17; 22.11 ± 4.97 years) or a control group (CG: n = 16; 24.5 ± 6.27 years). The total duration of the intervention phase (WBVT) was 6 weeks with a frequency of 3 sessions per week. Statistically significant differences were observed (P ≤ 0.05) between pre- and post-test in the power peak (Δ 1.91 W · kg^?1; P = 0.001), take-off velocity (0.1 cm · s^?1; P = 0.002) and jump height (Δ 0.4 cm; P = 0.002) for EG_WBVT. There were no statistically significant differences in any of the body composition and muscle architecture variables. Moreover, no significant differences were found between EG_WBVT and CG nor changes in muscle activity during take-off phase of the gastrocnemius and vastus lateralis pre- versus post-training. This study suggests that a 6-week WBVT programme with increasing intensity improves jump performance but does not alter muscle activity nor muscle architecture in healthy young men.     

对优秀自由式滑雪空中技巧运动员反应时与背力的研究

研究目的：自由式滑雪空中技巧运动属技能类难美项群的一个典型项目,对反应速度和肌肉力量都有很高的要求。通过对我国优秀自由式滑雪空中技巧运动员的反应时和背力的测量,并与体育学院大学生的进行对比,了解运动员的身体形态和机能特点,为今后我国优秀自由式滑雪空中技巧运动员的训练和选材提供一些参考。研究方法：以中国自由式滑雪空中技巧国家队的运动员16人作为研究组,体育学院04级社体大学生25人作为对照组,测量两组研究对象反应时和背力指标。研究结果：与对照组相比,运动员的背力较好,有统计学意义（P〈0.05）,反应时无统计学意义,但有存在差异的趋势;健将级运动员的背力和反应时与一般运动员相比,并无明显差异。研究结论：我国国家队的运动员已经拥有较好的背力,说明运动员在训练中已经加强了背力的训练;但反应时不理想,在今后的训练中有必要对此方面注意。     

影响篮球裁判员预判能力的因素分析

篮球裁判员预判能力好坏,对比赛能否顺利进行具有重要的意义。利用文献资料法从运动生理学、心理学角度出发,分析影响篮球裁判员预判能力的因素。通过对诸多因素分析,提出一些相关的具体训练方法,旨在提高篮球裁判员执裁水平。     

食用香料庚酸烯丙酯的合成

用由庚醛氧化制取的庚酸和由甘油裂解还原制得的烯丙醇为原料,反应温度为90-93℃,压力为1333Pa,在对甲苯磺酸催化下合成庚酸烯丙酯,产率为75％。庚酸烯丙酯的分子式为C10H18O2,为无色透明液体,有菠萝香气味,不溶于水,熔点-66,沸点210℃,可用于配制日化香精和食用香精。