水分胁迫对油松和侧柏生长发育的影响

模拟不同土壤含水量条件,对侧柏和油松的生长规律进行了研究。结果表明:高含水量土壤对这2种树的高度和地径变化的促进作用显著高于低含水量处理;叶绿素含量变化只有油松变化较为一致,在生长旺季的8月,两种树叶绿素含量相同,都是W3(60%)W4(70%)W2(50%)W1(40%)。     

一种新型燃气防泄漏多重保护装置的设计

介绍一种新型燃气防泄漏多重保护装置的结构和工作原理,并阐述了控制系统的特点。实验表明,它能在燃气使用前进行检测及自动报警、发生火灾或温度过高时自动关闭燃气开关、用户忘记关闭总闸时定时自动关闭总阀,该装置具有反应灵敏、制动迅速的特点,能够从根本上检测预防燃气的泄漏问题,具有十分广阔的应用前景。     

New technique of sex preselection for increasing female ratio in boar sperm model

In this study, we tried to optimize the porcine semen extender conditions to maximize the differences between live X chromosome-bearing (X) spermatozoa and to Y chromosome-bearing (Y) spermatozoa without a decline in the fertility rate at different pH conditions during storage. We observed the viability of X and Y boar spermatozoa in acidic (pH 6.2), original (pH 7.2), and alkaline condition (pH 8.2) for 5 days to investigate the effect of storage conditions on the X to Y spermatozoa ratio. The functional parameters of spermatozoa were also examined to evaluate sperm quality. Sperm motility was preserved at pH 7.2 and pH 6.2 for 3 days, while sperm motility at pH 8.2 decreased significantly after 2 days. Non-capacitated spermatozoa increased while capacitated spermatozoa decreased during storage. Sperm viability decreased significantly duration-dependent under all pH conditions, but there was no significant difference during storage at pH 6.2 and 7.2. The X: Y ratio of live spermatozoa in acidic condition was maximized (1.2:1) without affecting the sperm function and fertility-related protein expression after 2 days compared to original conditions. Moreover, insemination of sows using acidic extender increased the number of female pups on days 1 and 2 of preservation. These results indicate that the production of female offspring may increase when acidic BTS is used for 2 days without affecting the success rate of AI. Above all, this method is simple and economical compared to other methods.     

Effects of dietary lysozyme levels on growth performance,intestinal morphology,non‐specific immunity and mRNA expression in weanling piglets

The aim of the present study was to determine the effect of dietary lysozyme levels on growth performance, gut health and non‐specific immunity of weanling piglets. A total of 150 weanling piglets were allocated to six treatments. The piglets were fed the same basel diet supplemented with 0, 30, 60, 90 and 120 mg/kg lysozyme as well as antibiotics for 28 days. From day 14 to day 28 of dietary treatment, piglets fed 90 mg/kg lysozyme had greater average daily gain than piglets fed control diet. During the whole experimental period, piglets fed 120 mg/kg lysozyme tended to have greater average daily gain than piglets fed control diet. Compared with piglets fed control diet, piglets fed diets containing antibiotics and 90 mg/kg lysozyme had greater villus height to crypt depth ratio in duodenum and jejunum. Additionally, dietary supplementation of 60 and 90 mg/kg lysozyme as well as antibiotics enhanced the phagocytic activity of peritoneal macrophages in piglets. In conclusion, dietary lysozyme can accelerate the growth of weanling piglets by improving gut health and non‐specific immunity and supplementing 90 mg/kg lysozyme is as effective as antibiotics (20 mg/kg colistin sulphate + 50 mg/kg kitasamycin) in improving the growth performance of weanling piglets.     

Characterization and application of lactic acid bacteria for tropical silage preparation

Strains TH 14, TH 21 and TH 64 were isolated from tropical silages, namely corn stover, sugar cane top and rice straw, respectively, prepared in Thailand. These strains were selected by low pH growth range and high lactic acid‐producing ability, similar to some commercial inoculants. Based on the analysis of 16S ribosomal RNA gene sequence and DNA‐DNA relatedness, strain TH 14 was identified as Lactobacillus casei, and strains TH 21 and TH 64 were identified as L. plantarum. Strains TH 14, TH 21, TH 64 and two commercial inoculants, CH (L. plantarum) and SN (L. rhamnosus), were used as additives to fresh and wilted purple Guinea and sorghum silages prepared using a small‐scale fermentation method. The number of epiphytic lactic acid bacteria (LAB) in the forages before ensilage was relatively low but the numbers of coliform and aerobic bacteria were higher. Sorghum silages at 30 days of fermentation were all well preserved with low pH (3.56) and high lactic acid production (72.86 g/kg dry matter). Purple Guinea silage inoculated with LAB exhibited reduced count levels of aerobic and coliform bacteria, lower pH, butyric acid and ammonia nitrogen and increased lactic acid concentration, compared with the control. Strain TH 14 more effectively improved lactic acid production compared with inoculants and other strains. © 2016 Japanese Society of Animal Science     

小麦秸秆还田机粉碎装置性能影响因素试验与优化

利用设计的秸秆还田机粉碎装置进行了粉碎试验。以壳体包角、喂入速度、动定刀间隙为试验因素,秸秆的粉碎质量、粉碎功耗为试验指标,建立了粉碎质量和粉碎功耗的数学模型。随着喂入速度、壳体包角的增加和动定刀间隙的减小,粉碎功耗增大,粉碎质量提高。利用回归方程和主目标法,进行了参数的优化设计,结果为:粉碎室包角为70°、喂入速度为46.5m/s、动定刀间隙为10mm。     

天然花色苷的资源收集及稳定性测定

通过天然花色苷材料野外采集，共得到50种植物的花色苷样品，采用pH 1.0/pH 4.5溶液吸光值（△OD）差值法，对这些花色苷提取液进行了1年的测定和筛选，筛选出了花色苷颜色稳定性较好的桔梗（Platycodon grandiflorua A.）、蜀葵（Althaea. Rosea L.）、翠雀（Delphinium grandiflorum L.）和日本红菊（Chrysanthemum morifolium Ramat）等4种植物资源。对这4种花色苷进行酸碱性、光照、金属离子、热处理等条件下的稳定性测定，表明在pH4.0以下稳定，高于pH4.0稳定性则明显下降。日光、pH 1.0条件下上述4种花色苷溶液的半衰期分别为339d、255d、226d和234d。钙、镁离子对花色苷的稳定性无影响，铝、铜、锡和铁的存在降低花色苷的稳定性，其中铝影响较小，铜锡影响较大，铁影响最大。在100℃ 20min pH1.0热处理下色素损失率分别为2.7%、29.2%、20.0%和7.1%。桔梗花色苷稳定性明显优于其余3种花色苷。结果表明上述4种花色苷有希望开发成为食品色素添加剂。     

Loop细分技术在犁体曲面造型中的应用

阐述了细分方法的基本思想以及基于三角网格的Loop细分模式的原理和方法；提出了在相关几何造型、有限元分析和动态仿真软件配合下，基于OpenGL环境或CAD二次开发环境的复杂犁体曲面造型的细分方案；对犁体曲面的控制网格生成、边界限定等关键技术进行了讨论。利用该方法可以有效缩短复杂犁体曲面的造型、计算和分析时间。     

水土侵蚀过程分析的小波精细积分法

将小波配置方法和精细积分方法相结合,提出了一种对水土侵蚀模型进行数值分析的新方法——小波精细积分法。与传统的有限元方法相比,本文方法属于半解析方法,对时间步长不敏感,可有效提高计算效率。数值分析结果表明了该方法的有效性。     

温度对微小花蝽实验种群增长的影响

实验室饲养观察结果表明，在15－35℃温度范围内，随温度升高，微小花蝽的发育速率加快，成虫寿命缩短，在25℃下的世代存活率最高。根据实验数据计算出该虫的卵期发育起点温度为13．6℃，有效积温为1＝55．15日．度；若虫期发育起点温度为8．0℃，有效积温为270．1日．度。组建了25℃和30℃两种温度下的该虫的实验种群生命表。