用直角应变花测量某点应变的简便应变圆解法

通过理论推导，直接利用直角应变花的测量结果做出应变圆，并采用简单的方法解出主应变的大小和方向．     

Isokinetic and isometric muscle function of the knee extensors and flexors during simulated soccer activity: Effect of exercise and dehydration

Abstract

This study investigated the influence of dehydration during soccer-type intermittent exercise on isokinetic and isometric muscle function. Eight soccer players performed two 90-min high-intensity intermittent shuttle-running trials without (NF) or with (FL) fluid ingestion (5 ml · kg^?1 before and 2 ml · kg^?1 every 15 min). Isokinetic and isometric strength and muscular power of knee flexors and knee extensors were measured pre-exercise, at half-time and post-exercise using isokinetic dynamometry. Sprint performance was monitored throughout the simulated-soccer exercise. Isokinetic knee strength was reduced at faster (3.13 rad · s^?1; P = 0.009) but not slower (1.05 rad · s^?1; P = 0.063) contraction speeds with exercise; however, there was no difference between FL and NF. Peak isometric strength of the knee extensors (P = 0.002) but not the knee flexors (P = 0.065) was significantly reduced with exercise with no difference between FL and NF. Average muscular power was reduced over time at both 1.05 rad · s^?1 (P = 0.01) and 3.14 rad · s^?1 (P = 0.033) but was not different between FL and NF. Mean 15-m sprint time increased with duration of exercise (P = 0.005) but was not different between FL and NF. In summary, fluid ingestion during 90 min of soccer-type exercise was unable to offset the reduction in isokinetic and isometric strength and muscular power of the knee extensors and flexors.     

高产SOD乳酸菌培养条件的研究

本文从最适温度、初始pH、培养时间、培养基成份及培养方式等不同的方面对产SOD的乳酸菌发酵条件进行研究 找出最适发酵条件为:28～32℃,pH7.0,24h,静止培养     

Protective effects of therapeutic cold and heat against the oxidative damage induced by a muscle strain injury in rats

Abstract

The mechanisms of action of physical agents commonly used to treat skeletal muscle lesions are not well understood. In this study, we examined whether the modulation of oxidative stress is involved in the beneficial effects of cold and heat on gastrocnemius muscle strain injury. Adult male Wistar rats were submitted to a strain injury and treated with therapeutic agents in an isolated or combined form. Strain damage caused an increase in muscle and blood oxidative damage. We suggest that this oxidative damage might be related to the impairment of the muscle cell structure, since we observed a significant positive correlation between increased plasma creatine kinase activity and both oxidized dichlorofluoresceine and lipid peroxidation levels in muscle and blood. The intensity of the inflammatory response appears also to be an important factor in the genesis of oxidative damage immediately following a muscle strain injury. Therapeutic cold seems to be more effective in preventing the damage induced by a strain injury, possibly due to its capacity to control the impairment of muscle cell structure and to modulate the intensity of the inflammatory response that follows a muscle strain injury.     

微生物液化褐煤的工艺方法和作用效果研究

为有效利用煤炭资源、探索煤的微生物液化适宜方法,分别采用液体培养基溶煤和固体培养基溶煤方法.比较了10株茵种对硝酸氧化褐煤的液化作用效果.结果表明:对于微生物液体培养基溶煤,不同茵种在不同溶煤时期优势程度不一,溶煤效果不同.相比较而言,No.5、8和9茵种的溶煤速度快,总体溶煤效果好;采用粒径3-5mm煤样的固体培养基溶煤试验表明,No.2、4、5和7茵种的溶煤效果好,5d后可观察到液滴明显附着在煤粒表面上.对微生物液化溶煤的作用机理研究还发现,试验茵种在含氮培养基中的溶煤效果较好.大部分茵种符合微生物溶煤的碱溶机理.     

Gender influence on the adaptation of atrial performance to training

Background: High-intensity training has been associated with atrial remodelling and arrhythmias in men. Our purpose was to analyse atrial performance in female endurance athletes, compared to male athletes and controls. Methods: This was a cross-sectional study. We included four groups: female athletes, females controls, male athletes and male controls. Left (LA) and right atrial (RA) volumes and function were assessed using 2D and speckle-tracking echocardiography to determine peak atrial strain-rate at atrial (SRa) and ventricular contraction (SRs), as surrogates of atrial contractile and reservoir function, respectively. ANOVA and Bonferroni’s statistical tests were used to compare variables among groups. Results: We included 82 subjects, 39 women (19 endurance athletes, 20 controls) and 43 men (22 endurance athletes, 21 controls). Mean age was similar between groups (36.6?±?5.6 years). Athletes had larger bi-atrial volumes, compared to controls (women, LA 27.1 vs. 15.8?ml/m², p?<?0.001; RA 22.31 vs. 14.2?ml/m², p?=?0.009; men, LA: 25.0 vs. 18.5?ml/m², p?=?0.003; RA 30.8 vs. 21.9?ml/m², p?<?0.001) and lower strain-rate (women, LASRa ?1.60 vs. ?2.18?s^?1, p?<?0.001; RASRa ?1.89 vs. ?2.38?s^?1, p?=?0.009; men, LASRa ?1.21 vs. ?1.44?s^?1, p?=?1; RASRa ?1.44 vs. ?1.60?s^?1, p?=?1). However, RA indexed size was lower and bi-atrial deformation greater in female athletes, compared to male athletes. Conclusions: The atria of both male and female athletes shows specific remodelling, compared to sedentary subjects, with larger size and less deformation at rest, particularly for the RA. Despite a similar extent of remodelling, the pattern in women had greater bi-atrial myocardial deformation and smaller RA size.     

Comparison of estimates of Achilles tendon loading from inverse dynamics and inverse dynamics-based static optimisation during running

Tendon stress may be one of the important risk factors for running-related tendon injury. Several methods have been used to estimate Achilles tendon (AT) loading during a human performance such as inverse dynamics (ID) and inverse dynamics-based static optimisation (IDSO). Our purpose was to examine differences between ID and IDSO estimates of AT loading during running. Kinematic data were captured simultaneously with kinetic data. Imaging of the AT cross-sectional area was performed with ultrasound for 17 healthy runners (height: 170.2 ± 6.2 cm, mass: 63.9 ± 11.0 kg, age: 21.8 ± 1.4 years). AT stress, strain, and force were estimated from both ID and IDSO approaches. The two methods resulted in minimal differences (3.6–4.7%) in estimated peak AT stress, strain, and force (P = 0.051–0.054); however, IDSO estimates were greater (32.7–36.8%) during early-stance phase of running (P = 0.000–0.008). This difference in AT load during early-stance may be due to the inability of the ID to account muscle coactivation. The similarity between the peak AT loading for ID and IDSO methods revealed that the advantage of IDSO used to estimate muscle forces had little effect on the ankle plantar flexor peak forces during running. Therefore, the use of IDSO with a higher computational cost compared with ID may not be necessary for estimating AT stress during running.     

A new extension algorithm for cubic B-splines based on minimal strain energy

INTRODUCTION B-spline curves and surfaces have been widely used in Computer Graphics (CG) and Computer Aided Design (CAD) (Hoschek and Lasser, 1993; Piegl and Tiller, 1997). Many practical algorithms, such as those for position and derivatives evaluation, knot insertion, knot deletion and degree elevation, are usually implemented in a CAD system that uses B-spline as a shape design tool. In curve and surface design, a given B-spline curve or surface usually needs to be extended in …     

First genome sequence of Chilean Brucella canis SCL strain provides insights on the epidemiology and virulence factors,explaining differences between geographical origins

BackgroundBrucella canis is the etiological agent of canine brucellosis, a worldwide neglected zoonosis that constitutes one of the major infectious causes of infertility and reproductive failure in dogs. Although genomic information available for this pathogen has increased in recent years, here we report the first genome sequencing of a B. canis strain in Chile, and the differences in virulence genes with other B. canis strains.ResultsGenome assembly produced a total length of 3,289,216 bp, N50 of 95,163 and GC% of 57.27, organized in 54 contigs in chromosome I, and 21 contigs in chromosome II. The genome annotation identified a total of 1981 CDS, 3 rRNA and 36 tRNA in chromosome I, and 1113 CDS and 10 tRNA in chromosome II. There is little variation between the different strains and the SCL isolate. Phylogenetic analysis showed that the Chilean SCL strain is closely related to B. canis and B. suis strains. Small differences were found when compared to the Serbian isolate, but all strains shared the same recent common ancestor. Finally, changes in the sequence of some virulence factors showed that the SCL strain is similar to other South American B. canis strains.ConclusionsThis work sequenced and characterized the complete genome of B. canis strain SCL, evidencing the complete presence of all the genes of the virB operon, and minor changes in outer membrane proteins and in the urease operon. Our data suggest that B. canis was introduced from North America and then spread throughout the South American continent.How to cite: Borie C, Bravo C, Dettleff P, et al. First genome sequence of Chilean Brucella canis SCL strain provides insights on the epidemiology and virulence factors, explaining differences between geographical origins Electron J Biotechnol 2021;49. https://dx.doi.org/10.1016/j.ejbt.2020.10.002.     

仿扇贝形体的网壳结构建模及造型优化方法

扇贝形体是大自然进化的产物,是符合力学机理的空间壳体。本文针对扇贝形曲面进行形态仿生研究,应用计算机辅助几何设计中的双三次B样条方法重构曲面造型,并结合空间网壳结构特点,对曲面进行网格合理划分。同时,运用应变能最小原理,考察结构的整体力学性能,进行形体优化分析,最终实现了仿扇贝形体的网壳结构快速建模。