Muscle force characteristics of male and female collegiate cross-country runners during overground running

ABSTRACT

Males and females demonstrate unique running mechanics that may contribute to sex-related differences in common running related injuries. Understanding differences in muscle forces during running may inform intervention approaches, such as gait retraining addressing muscle force distribution. The purpose of this study was to compare muscle force characteristics and inter-trial variability between males and females during running. Twenty female and 14 male collegiate cross-country runners were examined. Three-dimensional kinetic and kinematic data were collected during overground running and used to estimate muscle forces via musculoskeletal modelling. Principle components analysis was used to capture the primary sources of variance from the muscle force waveforms. The magnitude of the forces for the hamstrings, gastrocnemius, and soleus muscles were higher across the majority of stance in male runners regardless of footstrike pattern. Males also demonstrated greater inter-trial variability in the timing of the peak gluteus maximus force and the magnitude of local peaks in the gastrocnemius force waveform. Male and female collegiate cross-country runners appear to employ unique lower extremity muscle force characteristics during overground running.     

过碳酸钠热分解动力学研究(Ⅱ)-最佳实验点的确定

采用置信域容积最小为目标的实验设计方法，对过碳酸钠分解动力学实验进行了统计设计，确定了最佳实验点的位置，研究结果表明，在过碳酸钠分解率0．1及0．85两个位置做实验，能够对过碳酸钠分解动力学模型中的两参数k和t0精确估值。     

丛枝菌根真菌对氮素的吸收作用和机制

丛枝菌根真菌可以与绝大多数陆生植物共生,它可以吸收铵态氮、硝态氮、一些氨基酸和一些复杂的有机氮素,吸收的氮素在根外菌丝中转化成精氨酸,并以这种形式运输到根内菌丝,在根内菌丝和根细胞界面,精氨酸再进一步转化为NH4^＋后转移到宿主植物体,参与植物氮素代谢,而转移的氮量及对宿主植物氮营养的贡献与宿主植物、真菌以及基质养分和水分条件有关．     

FeSO4溶液氧气氧化制备非晶δ-FeOOH的研究

以FeSO4为原料,在添加剂EDTA(乙二胺四乙酸二钠盐)存在下,氧气氧化Fe(OH)2可直接生成纯相非晶δ-FeOOH.研究了EDTA浓度、初始pH对δ-FeOOH形成的影响.使用TEM、IR对产物进行了表征,并讨论了在EDTA作用下的氧气氧化Fe2 的反应机理.     

低浓度苯胺在大孔树脂上吸附的动力学研究

测定了水相中苯胺在NKA—Ⅱ和AB-8这2种大孔吸附树脂上的吸附等温线和吸附速率曲线．结果表明：极性的NKA—Ⅱ对苯胺的吸附量要高于弱极性的AB-8对苯胺的吸附量，苯胺在2种吸附树脂上的相平衡关系符合Freundlich方程；苯胺在NKA—Ⅱ和AB-8上的吸附受腱扩散控制．动态吸附实验和模拟结果表明：模拟透过曲线与实验透过曲线比较吻合，所建立的模型能够较好地描述苯胺在2种大孔吸附树脂填充柱上的吸附透过过程．     

水环境监测工作中存在的几个问题

说明了水环境监测工作中存在的几个问题,并对产生问题的原因进行了分析。     

苯甲酸氧弹燃烧法测定植物体中的硼含量

以苯甲酸为助燃剂，用氧弹燃烧法灰化植物体进行硼元素测定，操作简便、快捷、无污染。     

Recovery of Dilute Acetic Acid by Catalytic Distillation Using NKC-9 as Catalyst

The reaction kinetics of dilute acetic acid with methanol using NKC-9 as catalyst was studied at temperatures of 308 K, 318 K, 323 K, 328 K. The kinetic model based on Langmuir-Hinshel-wood rate model was derived and the activation energy was 6.13×104 kJ/kmol. The experiment of recovery of dilute acetic acid was conducted in a packed bed catalytic distillation column. The optimal process parameters and operational conditions determined to make up to 85.9% conversion of acetic acid are as follows:the height of catalyst bed is 1 100 mm, reflux ratio is 4:1, and the ratio of methanol to acetic acid is 2:1. The method can be used as a guide in industrial scale recovery of 15%-30% dilute acetic acid.     

^125I在鹌鹑Coturnix coturnix中的吸收动态及其分布

利用同位素示踪法研究了125I(NaI)在鹌鹑Coturnix coturnix中的吸收动态及其分布.鹌鹑对经口喂的125I的吸收过程可以分为快清除期和平台期,0～1 d为快清除期,在这期间,鹌鹑快速的排出进入体内的125I.1～7 d为平台期,鹌鹑体内的125I维持在一个相对恒定的平台,此时体内的放射性活度占起始活度的10%～15%,表明鹌鹑能利用部分进入体内的碘.进入体内的125I主要分布于甲状腺中,5 h时125I在甲状腺中的比活度高达6180 060Bq·g-1,约占体内总量的75%～80%.