Influence of vermicomposting on solid wastes decomposition kinetics in soils

The effect of vermicomposting on kinetic behavior of the products is not well recognized. An incubation study was conducted to investigate C mineralization kinetics of cow manure, sugarcane filter cake and their vermicomposts. Two different soils were treated with the four solid wastes at a rate of 0.5 g solid waste C per kg soil with three replications. Soils were incubated for 56 d. The CO2-C respired was monitored periodically and a first-order kinetic model was used to calculate the kinetic pa-rameters of C mineralization. Results indicated that the percentage of C mineralized during the incubation period ranged from 31.9% to 41.8% and 55.9% to 73.4% in the calcareous and acidic soils, respectively. The potentially mineralizable C (C0) of the treated soils was lower in the solid waste composts compared to their starting materials. Overall, it can be concluded that de-composable fraction of solid wastes has decreased due to vermicomposting.     

Extraction and stripping kinetics of copper （Ⅱ） by N902 using single drop technique

The kinetics of extraction and stripping of copper （Ⅱ） was investigated by the single drop technique with a new extractant N902 （a derivative of the salicylal-doxime） and the rate equations of extraction and stripping were derived, respectively. The apparent activation energies of extraction and stripping were estimated to be 20.14 kJ/mol and 30.0 k J/mol.     

酯水解的动力学常数测定实验的改进

对酯水解的动力学常数测定实验进行改进,通过使用带恒温装置的紫外可见分光光度计,在一定pH值和恒温条件下测定具有三脚架型的二乙烯三胺锌配合物催化磷酸双酯BNPP水解的吸光度随时间的变化,进一步求算出催化磷酸双酯水解的二级速率常数,有助于学生掌握测定配合物催化酯水解的动力学参数。     

The effects of baseball bat mass properties on swing mechanics,ground reaction forces,and swing timing

Swing trajectory and ground reaction forces (GRF) of 30 collegiate baseball batters hitting a pitched ball were compared between a standard bat, a bat with extra weight about its barrel, and a bat with extra weight in its handle. It was hypothesised that when compared to a standard bat, only a handle-weighted bat would produce equivalent bat kinematics. It was also hypothesised that hitters would not produce equivalent GRFs for each weighted bat, but would maintain equivalent timing when compared to a standard bat. Data were collected utilising a 500 Hz motion capture system and 1,000 Hz force plate system. Data between bats were considered equivalent when the 95% confidence interval of the difference was contained entirely within ±5% of the standard bat mean value. The handle-weighted bat had equivalent kinematics, whereas the barrel-weighted bat did not. Both weighted bats had equivalent peak GRF variables. Neither weighted bat maintained equivalence in the timing of bat kinematics and some peak GRFs. The ability to maintain swing kinematics with a handle-weighted bat may have implications for swing training and warm-up. However, altered timings of kinematics and kinetics require further research to understand the implications on returning to a conventionally weighted bat.     

我国优秀男子跳高运动员起跳阶段摆动腿技术的运动学研究

背越式跳高起跳技术主要由起跳腿的蹬伸技术与摆动腿的摆动技术所组成。目前,大多数人们集中于跳高起跳的"蹬伸"技术研究,对起跳阶段的"摆动"技术研究相对较少。文章运用现场技术录像和运动图像解析的方法,对我国优秀男子跳高运动员在起跳阶段摆动技术进行解析研究,结果表明:我国优秀男子跳高运动员起跳前摆动腿最大缓冲幅度比较大;在起跳阶段摆动腿蹬离瞬间,摆动腿膝关节角度变化较小。背越式跳高起跳过程中的摆动腿缓冲阶段,身体重心的高度、摆动腿膝角的变化情况与助跑水平速度的损失有显著性相关。助跑最后一步摆动腿的伸膝角度、伸膝速度与起跳腿着地时摆动腿的摆动速度、摆动腿离地后的最大摆动速度都有高度的相关性。     

Judo

Twenty male judo players (10 black belt; 10 novice) executed the major outer leg reap, osoto‐gari, with maximal effort. Each throw was recorded within the two‐dimensional sagittal plane using a 60 Hz video camera. Kinematic data that best described the power of the ‘tori's’ (thrower's) sweeping leg and the velocity of the ‘uke's’ (recipient's) falling body were analysed using a Peak Performance Technologies Inc. Motus system. Data from black belt and novice groups were statistically analysed using a one‐way MANOVA (p = .05). Statistical analysis found only two variables for the ‘tori’ (peak angular velocity of the trunk; TTRK, and peak angular velocity of the ankle; TANK) to be significantly different. Large TTRK values for the black belt group indicated a proficient ability to create large momentum on the upper body of the ‘uke’. Significantly larger differences in trunk rotation velocities of the ‘uke’ by the black belt group reinforced this notion. These differences were attributed to good upper body to upper body contact or impact, which is considered an important aspect of the ‘osoto‐gari’. Significant differences in TANK values stressed the importance of executing plantar flexion near sweep contact. The results emphasised the importance of using the sweeping leg in a sequential kinetic link motion rather than as a single rigid segment.     

Have we underestimated the kinematic and kinetic benefits of non-ballistic motion?

Explosive upper-body movements, with which the load is not thrown (non-ballistic), may comprise a phase during which forces are produced in opposition to the motion of the load. Thirty men completed three test sessions (free weight, ballistic, and pneumatic), each consisting of a one-repetition maximum (1-RM) and four explosive repetitions of a bench press at six loads (15, 30, 45, 60, 75, and 90% 1-RM). The end of the lifting phase for the non-ballistic conditions (free weight and pneumatic) was defined by: the point of peak barbell displacement and the point at which the vertical force became negative (positive work). When analysed by peak displacement, the ballistic condition elicited significantly greater mean velocity, force, and power at loads of 15–60% 1-RM compared with the free weight condition. When the period of negative work was removed, the mean free weight velocity, force, and power at loads below 60% 1-RM increased. Consequently, the only differences between the free weight and ballistic conditions were found at loads of 15% and 30% 1-RM. Including a period of negative work may underestimate all kinematic and kinetic variables dependent on the time to, or position of, the end of the lifting phase, for non-ballistic efforts.     

Biomechanical comparison of the double-push technique and the conventional skate skiing technique in cross-country sprint skiing

Abstract

The aims of the study were to: (1) adapt the “double-push” technique from inline skating to cross-country skiing; (2) compare this new skiing technique with the conventional skate skiing cross-country technique; and (3) test the hypothesis that the double-push technique improves skiing speed in a short sprint. 13 elite skiers performed maximum-speed sprints over 100 m using the double-push skate skiing technique and using the conventional “V2” skate skiing technique. Pole and plantar forces, knee angle, cycle characteristics, and electromyography of nine lower body muscles were analysed. We found that the double-push technique could be successfully transferred to cross-country skiing, and that this new technique is faster than the conventional skate skiing technique. The double-push technique was 2.9 ± 2.2% faster (P < 0.001), which corresponds to a time advantage of 0.41 ± 0.31 s over 100 m. The double-push technique had a longer cycle length and a lower cycle rate, and it was characterized by higher muscle activity, higher knee extension amplitudes and velocities, and higher peak foot forces, especially in the first phase of the push-off. Also, the foot was more loaded laterally in the double-push technique than in the conventional skate skiing technique.     

中、外优秀男子百米途中跑运动学研究及模型的构建

通过文献资料调研、影片解析等方法对中、外优秀男子短跑运动员途中跑最高速度时一个单步的技术结构进行运动学研究。通过对着地瞬间、后蹬瞬间、腾空瞬间的运动学指标分析，总结出男子优秀运动员共性的技术原理，运用灰色关联分析中关联度的大小，建立优秀男子百米专项运动技术模型。     

H2O/CO2污染对煤油燃料超声速燃烧影响数值研究

在纯净空气与H₂O/ CO₂污染空气来流对比试验结果基础上,采用数值计算方法和化学动力学方法,研究了H₂O和CO₂污染组分对煤油燃料超声速燃烧的影响,获得了试验手段难以得到的燃烧室流场参数和性能数据。完成了相应的煤油燃料超声速燃烧室二维数值计算,其中匹配了进口总温、总压、马赫数、氧气摩尔分数和工作当量油气比。将数值计算结果与相应试验测量值进行了对比分析,并结合燃烧室流场数据、性能参数分析了H₂O和CO₂污染的动力学影响、以及对燃烧室性能的影响。研究表明:(1)数值计算结果与实验测量值总体上吻合,两种手段均体现了纯净空气来流时不同煤油当量油气比的燃烧室性能,并反映了一致的“污染效应”影响趋势;(2) H₂O污染、H₂O+ CO₂污染的存在降低了煤油燃料超声速燃烧室性能,体现在燃烧诱导压升、燃烧效率、流向冲量增量的下降,而且随着污染组分含量的增加,燃烧室性能下降越加显著。 