芳砜纶纤维原料对其成纱及织物性能的影响

研究了芳砜纶纤维纺纱中,纤维长度对成纱性能影响的规律。采用不同长度的芳砜纶纤维在棉纺设备上进行纺纱对比,并对不同长度芳砜纶纤维纱织物的性能进行对比得出:在纱支一定时,芳砜纶纱及织物的拉伸性能随纤维长度增加而增加;纤维超过一定长度后拉伸性能下降,成纱毛羽则是先减少后增加。成纱条干在一定的纤维长度范围内,变化不大,纤维长度过长,则成纱条干明显恶化。芳砜纶织物的撕破性能变化与成纱拉伸性变化趋势类似。芳砜纶成品性能最佳时纤维长度为52 mm。     

特高强度大规格钢丝绳吊索制作

介绍特高强度大规格钢丝绳吊索生产控制要点及工艺流程,分析影响索长和吊索强度的因素,通过钢丝绳预张拉处理、恒载索力定尺、二次测量法测量索长,并进行温度修正计算及长度调整等工序,确保索长精度达1/5 000;采用四氯乙烯作为清洗剂清除钢丝表面油污,锚杯预热温度控制在100～110℃,浇铸温度控制在(460±10)℃,浇铸熔融合金的化学成分控制:w(Zn)为(98±0.2)%,w(Cu)为(2±0.2)%,从而保证锚头合金浇灌填充率大于95%,被检测吊索强度不小于钢丝绳最小破断力。     

Effects of chop length of alfalfa and corn silage on milk production and rumen fermentation of dairy cows

Effects of chop length (shorter = 10 mm or longer = 19 mm) of alfalfa silage and corn silage were determined in 16 midlactation Holstein cows using a 4 × 4 Latin square design with a 2 × 2 arrangement of treatments. Experimental periods were 21 d long and consisted of 14 d of adaptation and 7 d of sampling. Cows received total mixed ration containing (dry matter basis) 44.0% barley grain-based energy supplement, 12.6% protein supplement, and 21.7% longer chop or shorter chop alfalfa silage and 21.7% longer chop or shorter chop corn silage. Reducing the chop length of alfalfa silage and corn silage reduced the average geometric particle length from 14.4 to 11.0 mm and from 14.2 to 10.4 mm, respectively. Reducing the chop length of both silages reduced the proportion of the diets retained by the 8-and 19-mm screen of the Penn State Particle Separator from 55.0 to 46.0% of dry matter. Reducing the alfalfa chop length increased total rumen volatile fatty acids at 4 to 5 h after feeding but did not affect rumen pH at 4 to 5 h after feeding, feed intake, and milk production. Reducing the corn silage chop length increased dry matter intake from 22.3 to 23.2 kg/d, increased rumen pH at 4 to 5 h after feeding from 6.12 to 6.20, but did not alter rumen volatile fatty acids at 4 to 5 h after feeding or milk production. Daily milk yield, milk fat percentage, and milk protein percentage averaged 38.2 kg/d, 2.62%, and 3.29%, respectively, across all diets. The low milk fat percentages suggest that all diets induced subacute ruminal acidosis (SARA), whereas the rumen pH did not indicate SARA. This discrepancy could be due to a difference in the time of rumen pH measurement and the time of the lowest rumen pH. Hence, the pH data need to be interpreted with caution. Diets could have induced SARA, because for all experimental diets the content of forage neutral detergent fiber was lower than recommended for barley grain-based diets.     

Pelvic suspension and fast post-mortem chilling: Effects on technological and sensory quality of pork - A combined NMR and sensory study

The effects of pre-rigor excision, which results in a fast post-mortem chilling; pelvic suspension, which results in a muscular stretching; control treatment of m. longissimus dorsi on water distribution measured by (1)H NMR relaxometry and on sensory properties were investigated in two sub-studies including a total of 16 pigs. Determination of sarcomere length revealed significant effects of the treatments on the degree of contraction, as pre-rigor excision and pelvic suspension resulted in shorter and longer sarcomere length, respectively. In addition, an effect of treatment on pH measured at 24h post-mortem was found, as pre-rigor excision was associated with a higher ultimate pH. NMR measurements revealed that water distribution in the meat was affected to a minor degree by the various treatments. However, an interaction between treatment and ageing period was observed, as the data demonstrated an effect of pre-rigor excision on water distribution in the cooked samples when meat was only aged for 2 days, but this effect was eliminated when meat was aged for 5 days. The effect of pre-rigor excision on water distribution in cooked meat after 2 days of ageing is suggested to reflect structural constraints in the meat that are eliminated during ageing. Sensory analyses demonstrated strong interactions between treatment and position on the muscle and between treatment and ageing period. However, in general pre-rigor-excised meat was sensed as significantly juicier compared with the other two treatments. Accordingly, the study demonstrates that under the present conditions the ultimate pH is more important for juiciness than the sarcomere length.     

Effect of temperature on the development of the yam moth, Dasyses rugosella Stainton (Lepidoptera: Tineidae)

Studies on the effect of temperature on the development of the yam moth, Dasyses rugosella Stainton were carried out in the laboratory at four different temperatures, 20°C, 24°C, 29°C and 33°C. The mean fecundity per female at 20°C, 24°C, 29°C and 33°C was 37.6±1.9, 84.2±2.7, 112.3±3.9 and 109.3±3.9 eggs, respectively. Oviposition period ranged from 4.7 days at 20°C to 2.9 days at 33°C. Hatchability of eggs was highest at 29°C with 70.0% and lowest at 20°C with 15.0%. The developmental time decreased with increase in temperature. The mean developmental time at 20°C, 24°C, 29°C and 33°C was 13.8±0.3, 7.8±0.2, 5.1±0.2 and 3.9±0.2 days for the egg, 90.0±0.7, 50.1±0.7, 36.1±0.8 and 23.6±0.8 days for the larval stages, 22.3±2.6, 12.2±0.2, 10.1±0.1, and 7.8±0.2 days for the pupa and 126.1±0.8, 70.1±0.8, 51.3±0.9, and 35.1±0.8 days for the period from egg hatching to adult emergence, respectively. Since fecundity, oviposition and development of the moth were impaired at 20°C, storage of yam tubers at low temperatures (well below 20°C but not lower than 12°C to avoid chilling injury) will significantly retard the development of D. rugosella and help in its control. Unmated individuals lived longer than their mated counterparts. Adult females were always larger than the males. The wing span of the female ranges from 16.9-18.5 and in males from 13.0-15.0 mm. The body length for males ranged from 5.0-6.5 and was 6.5-9.0 mm for females.     

喷气织机储纬器分析及维护

介绍了储纬器的作用与分类,重点分析了喷气织机储纬定长装置工作原理、特点及储纬器发热故障的维修方法。     

Evidence against the non-enzymatic calcium theory of tenderization

The objective of the present study was to determine whether variation in the tenderization of lamb longissimus could be attributed to variations in the rise in free calcium postmortem and sarcomere lengthening post rigor. The longissimus muscle of 10 crossbred lambs (Romney×Coopworth) was sampled at 1 and 7 days postmortem for determination of MIRINZ shear force, myofibrillar fragmentation index (MFI), sarcomere length, free calcium, and proteolysis of troponin-T. Despite considerable variation in tenderness and tenderization of the muscles, sarcomere lengthening was not observed. The concentration of free calcium at 7 days postmortem correlated significantly with the MFI (r=0.640; P<0.05) and tended to correlate with the shear force (r=−0.596; P<0.1) and degradation of troponin-T (r=0.625; P<0.1). Degradation of troponin-T was significantly correlated with tenderization (r=0.664; P<0.05). Troponin-T is a calpain substrate, but reportedly is not degraded through a direct effect from calcium. The present results, therefore, suggest that the variation in free calcium in postmortem muscle affects tenderization through an effect on the calpain system and not through a direct effect of calcium on myofibrillar proteins. Consequently, the results of this study do not support the (calcium) theory that calcium directly affects tenderization.     

纸的断裂韧性及其与纤维长度的关系

介绍了用断裂基功的概念测定纸张断裂韧性的新方法。并用此法研究了纤维长度对断裂韧性的影响，表明纸的断裂韧性与纤维长度几乎成直线关系；断裂韧性对纤维长度的依赖性比撕裂和抗张强度大。     

羽毛纱的纺纱研究

采用小针筒织带机形式的多功能纺纱小样机纺制了羽毛纱,详细介绍了纺纱工艺原理和工艺过程,探讨了羽毛的密度和长度与其他参数的关系,并且总结了生产羽毛纱的影响因素,认为纺制羽毛纱时主副电动机频率应协调配合,并调节好织针、割刀和导纱钩的位置.     

智能变电站光缆配套材料的选型及优化

介绍了各类光缆产品及光纤连接器,为智能变电站光缆和光纤连接器的选型提供了参考.结合实际工程案例,对智能变电站各智能电子设备间的光缆连接方式提出了可行方案,按照国家相关标准,论述了变电站内光缆的敷设方式.