Cuticle and cortical cell morphology and the ellipticity of cashmere are affected by nutrition of goats

Cuticle scale edge height and frequency are used to identify animal fibres but exhibit a large range in dimensions, the reasons for which have not been elucidated. Cuticle and cortical cell dimensions along with the ellipticity of fibres were investigated in cashmere samples from a controlled nutrition experiment. Cuticle scale frequency, cuticle thickness, cortical cell dimensions and ellipticity were affected by nutritional treatment, with significant differences between cashmere from goats fed to grow and those which maintained live weight or lost weight. Cuticle scale frequency, cell thickness and ellipticity (contour) varied with fibre diameter, fibre growth rate and the size of the animals. Cuticle thickness and ellipticity were related. Cashmere grown by goats with higher levels of nutrition had longer cortical cells with greater diameter, volume and a higher length:diameter ratio compared with cashmere grown by goats in restricted nutrition treatments. The results show that the fundamental physical structures of cashmere do not have fixed dimensions. The consequences of the variations in cuticle morphology and ellipticity will be variation in surface friction, bending rigidity, softness, lustre, colour attributes, fibre cohesion during processing, felting and wear properties of textiles. There are also important consequences upon the determination of cashmere origin.     

Natural gene expression variation studies in yeast

The rise of sequence information across different yeast species and strains is driving an increasing number of studies in the emerging field of genomics to associate polymorphic variants, mRNA abundance and phenotypic differences between individuals. Here, we gathered evidence from recent studies covering several layers that define the genotype–phenotype gap, such as mRNA abundance, allele‐specific expression and translation efficiency to demonstrate how genetic variants co‐evolve and define an individual's genome. Moreover, we exposed several antecedents where inter‐ and intra‐specific studies led to opposite conclusions, probably owing to genetic divergence. Future studies in this area will benefit from the access to a massive array of well‐annotated genomes and new sequencing technologies, which will allow the fine breakdown of the complex layers that delineate the genotype–phenotype map. Copyright © 2016 John Wiley & Sons, Ltd.     

通风量对菇渣好氧发酵温度时空特性的影响

采用不同通风量进行菇渣与猪粪高温共发酵,研究通风对发酵过程中堆体温度的时空变化的影响。结果表明,通风使堆体温度呈现出明显的梯度效应,不同处理各发酵时期的温度分布均由剖面中部向四周不断降低。高温区域的位置和面积随发酵时间呈动态变化规律,升温期温度在发酵罐中上部积聚,高温分布区类似椭圆形,高温期椭圆面积逐渐向堆体中部扩散和扩大,随后高温面积不断递减并向中下部迁移,降温期堆体各区域温度趋于一致。由等值线的疏密程度可知,温度的空间变异性大体呈现出高温期>第2次高温期>升温期>降温期的规律。结合试验各阶段的温度变化并考虑节能降耗,得出发酵升温期和高温期分别以0.05,0.067m3/(d·m3)进行通风,二次高温期与降温期以0.033 m3/(d·m3)进行通风条件最佳。     

Application of a Damped Spring-Mass Human Vibration Simulator in Vibration Testing of Vehicle Seats

Abstract

There is a need for standardized methods for testing vehicle seats. Such methods would allow for the direct comparison of the merits of seats of diverse types and designs. At the present time standardized testing procedures are not possible because the dynamic characteristics of the human subjects occupying the seat during testing vary widely from man to man and affect the seat response. Testing with dead weight loading does not accurately portray the dynamic characteristics of the seat. A damped spring-mass system closely approximating to the dynamic characteristics of a seated man to vertical modes of vibration has been developed as the basis on which a standardized vehicle seat testing procedure can be built. Analysis of the problem by means of mechanical impedance techniques indicated that a two-degree-of-freedom system was sufficient to simulate the major dynamic characteristics of man in the frequencies below 10 Hz where seat vibration is most severe. Test procedures have been developed which utilize the man-simulator as the seat load. Results of these tests will be useful because they do not contain the subject variable and therefore can be compared directly with results obtained in other laboratories using the same methods.     

电流密度对微弧氧化热损耗和膜层致密性的影响

在硅酸盐电解液体系中对AZ91D镁合金进行微弧氧化试验,考察了不同电流密度(3、6、9、12、15 A/dm2)对溶液温度变化量、热损耗和膜层致密性的影响.结果表明,随电流密度的增加,体系温度变化量从18℃持续增加到33℃;体系热损耗先减小后增大;膜层的致密度先增大后减小.     

Mathematical model and tooth surfaces of recess action worm gears with double-depth teeth

In this study, the surface equations of recess action (RA) worm gears with double-depth teeth, generated by a ZN worm-type hob cutter, are proposed. Based on the generation mechanism and the theory of gearing, a mathematical model of a series of worm gears, semi RA, full RA and standard proportional tooth types, with double-depth teeth is developed as the function of design parameters of the ZN worm-type hob cutter. According to the derived tooth surface equations, computer graphs of a series of worm gears with double-depth teeth are plotted. Tooth surface variations of the generated RA worm gears due to the varying pitch line, pressure angle and tooth height of the hob cutter are also investigated.     

Computational study of effects of traffic force on the ventilation in highway curved tunnels

A computational study using dynamic mesh method was carried out to investigate the effects of traffic force caused by a moving vehicle on ventilation in a straight road tunnel and several curved road tunnels with various radii. It has been found that the effect of the radius of the curved tunnel on the traffic force is significant, especially in a curved tunnel with a smaller radius. The traffic force induced by a moving vehicle and the effective drag coefficient increase with the decrease of the radius of the tunnel. The difference between the traffic force in curved tunnels and that in a straight tunnel is negligible when the radius is greater than 2000 m. The static pressure around the vehicle is significantly lower than it is away from vehicle due to the combination of the boundary layer separation and the airflow retardation. And the lowest value occurs at the front of the vehicle. With the decrease of the radius of curved tunnels, the suction around and behind the vehicle is obviously subjected to the limited space due to a bigger vortex approximately approaching the right concave wall and this consequently causes a lower static pressure and a lower dynamic pressure.     

单调荷载下的砂土宏观和细观力学性状关联度试验研究

基于压缩试验的细观观测,研究了土体宏观力学性状和颗粒细观参数的定量关系。通过对单调压缩荷载下砂土颗粒的运动分析,研究了砂土颗粒的长轴L、短轴B、y轴投影长度、形心x坐标与形心y坐标5个细观力学指标与宏观力学性状孔隙比的关联,提出细观力学参数与孔隙比的量化计算式。依据中砂半模压缩试验结果修正了量化计算式,砂样顶面圆心处^#1观测点的计算孔隙比e小于砂样底面圆心处^#2观测点的e;砂样1/2高度水平面上,环刀与砂样中轴线间距离的中点^#3观测点的e小于环刀内侧壁处^#4观测点的e,根据计算结果绘出各观测点的e–p曲线。各观测点的计算孔隙比表明,观测点位置影响了颗粒运动及孔隙比变化。通过对砂土细观力学性状与孔隙比之间关联度的试验研究,从散体细观力学出发,提出了一种基于试验的土体宏、细观力学性状相关联的研究方法。     

邕江水源水质特征与变化趋势

通过对南宁市两个水源点2007-2009年监测数据的统计分析,得出邕江水源的自然水质特征和污染指标表现情况.结果表明,邕江原水的自然水质特征主要表现为浊度受季候水期影响较大,水的酸碱度为中性略偏弱碱,硬度适中;粪大肠菌群指标对邕江水源水质状况影响最大,近年来邕江水源的水质总体上保持稳定,未出现劣变的趋势.