大型贯流式泵站快速门加速启动过渡过程

为研究大型贯流式泵站机组闸门加速启动过程中的外特性参数变化及流态变化,对灯泡贯流泵机组进行三维建模,采用Fluent软件中的UDF来控制闸门的启动过程,使用铺层法动网格技术来控制闸门处网格生成与消灭,并设定S-A模型作为湍流模型,对灯泡贯流泵机组启动过程进行瞬态数值模拟.计算结果表明:当贯流泵机组快速门以10倍设计速度启动时,机组的转速与流量将以更快的速度达到额定转速与额定流量,同时瞬间最大倒灌流量相比未加速启动时增加了30%.当贯流泵机组处于倒流状态时,靠近轮毂处叶轮叶道压力面的压强呈现出从叶轮进水边向出水边逐渐递增的分布规律.当机组处于零流量的临界状态时,混乱的流态导致压力集中及脱流现象加重,叶轮进水边负压区范围扩大且程度加深.     

基于玻璃化转变的稻谷变温热风干燥工艺研究

为保证稻谷干燥后品质、提高干燥效率,基于不同含水率稻谷的玻璃化转变温度,提出变温热风干燥工艺。采用三因素五水平中心组合试验方法,以稻谷温度、初始含水率和热风风速为影响因素,以稻谷爆腰指数、整精米率和干燥时间为评价指标,研究稻谷玻璃化转变温度、恒温和变温干燥特性,模拟解析稻谷干燥过程中传热传质规律,以5、10、15℃的变温幅度进行变温干燥试验。结果表明,稻谷玻璃化转变温度与其含水率呈负相关,恒温干燥最佳工艺参数为稻谷温度47℃、初始含水率22.0%、热风风速0.50 m/s,干燥后稻谷爆腰指数70、整精米率57.67%、干燥时间195 min;与恒温干燥相比,以5℃和10℃为变温幅度的变温干燥工艺,干燥后稻谷爆腰指数分别降低了20和10,整精米率提高12.6、7.7个百分点,干燥时间缩短30 min和60 min。研究表明,基于玻璃化转变的稻谷变温热风干燥工艺明显改善了稻谷干燥后品质,提高了干燥效率。     

Comparison of cholesterol levels among lipoprotein fractions separated by anion-exchange high-performance liquid chromatography in periparturient Holstein–Friesian dairy cows

Changes in lipoprotein profiles occur in dairy cows during the periparturient period and in cows with transition cow disease. Here, the lipoprotein profiles of Holstein–Friesian dairy cows during the periparturient period were obtained by anion-exchange, high-performance liquid chromatography to evaluate the usefulness of lipoprotein profile evaluation during the periparturient period and in cows with fatty liver and milk fever. Lipoprotein levels (including total and high- (HDL-C) and low-density lipoprotein (LDL-C) cholesterol) in 10 healthy cows were low 4 weeks prepartum, with the lowest values at calving or within 1 week of calving; the values increased at 8 weeks postpartum. The lipoprotein levels were measured in 16 cows diagnosed with fatty liver (n=10) or milk fever (n=6) and compared to 10 healthy dairy cows. A significant difference was observed in HDL-C between healthy cows (at calving and 1 week postpartum), and the fatty liver and milk fever cows. Cows with fatty liver and milk fever had a lower mean HDL-C than the 10 healthy dairy cows at calving and 1 week postpartum. HDL-C might be a good indicator of energy balance for differentiating healthy cows from those with transition cow disease.     

MicroRNA-145 inhibits epithelial-mesenchymal transition in human renal cancer A-498 cells by ADAM28

AIM: To investigate the inhibitory effect of microRNA-145 (miR-145) on epithelial-mesenchymal transition (EMT) in renal cancer A-498 cells. METHODS: The A-498 cells were transfected with miR-145 mimics (M145) and mimic negative control(MNC), which served as M145 group and MNC group, respectively. Mock control (MC) group was set up using untreated A-498 cells. The expression level of miR-145 in each group was detected by RT-qPCR. Transwell assay was used to detect the invasion ability of the cells. The protein expression of vimentin, E-cadherin and ADAM28 was determined by Western blot. Bioinformatic method was used to predict the target genes of miR-145. Antagonistic effect of ADAM28 over-expression on the inhibition of EMT by miR-145 was detected by Western blot. The relationship between miR-145 and ADAM28 was analyzed by dual-luciferase reporter assay. RESULTS: The expression level of miR-145 in M145 group was significantly up-regulated than that in MC group (P<0.05). The number of invasive cells in M145 group was 12.78±3.37, which was significantly lower than that in MC group (P<0.05). ADAM28 may be the target gene of miR-145. Compared with MC group, the protein expression of vimentin and ADAM28 in M145 group was significantly decreased (P<0.05), while the protein expression of E-cadherin was significantly increased (P<0.05).After ADAM28 over-expression, the protein expression of vimentin in the A-498 cells of M145 group was significantly increased (P<0.05), and the protein expression of E-cadherin was significantly decreased (P<0.05). The results of dual-lucife-irasei reporter assay showed that ADAM28 was a downstream target gene of miR-145. CONCLUSION: miR-145 may inhibit the expression of EMT-related proteins through the downstream target gene ADAM28 and inhibit the EMT process of renal cancer A-498 cells.     

建筑玻璃幕墙的节能技术分析

随着建筑玻璃幕墙的被广泛应用,在提升建筑物的通透性、艺术性的同时,对现有的节能技术进行分析,并提出了建筑玻璃幕墙节能的技术要求及其可行性.     

FRW阻燃胶合板的DMA分析

目前世界范围内木材资源短缺的情况日益加剧,发展人造板工业已成为世界各国解决木材资源严重不足的重要途径.其中,胶合板作为室内装饰的主要材料,其产量和需求量都在急剧增长.我国胶合板产量从1980年的33.00万m3增长到2004年的2 098.62万m3,呈现大幅度增长的趋势(张文标等,2000).但由于普通胶合板具有易燃性,在许多领域的应用上受到限制.因为一旦发生火灾,不仅造成重大的经济损失,而且往往会发生人员伤亡.1950-2003年全国共发生火灾4 177 730起,直接经济损失2 434.525 1亿元,因火灾死亡174 855人,受伤329 352人.     

空调制冷行业与环保的关系

本文就大气保护制冷行业的关系并从保护臭氧层、大气变暖的角度，论述了空调制冷行业与环保的关系。     

稻壳灰同时制备脱色剂和水玻璃的研究

基于稻壳灰（RHA）含有均匀分布的主要由SiO2组成的高含量矿物质的事实，研究了RHA综合利用的方法。RHA先经碱法处理后转化为水玻璃和脱硅RHA（DRHA），然后DRHA用硫酸活化制得应用于植物油精炼中的脱色剂纯RHA（PRHA）。分别探讨了影响水玻璃模数和PRHA脱色能力的因素。结果表明，在2-3mol／L范围内改变NaOH浓度或在2-3h范围内改变溶煮时间，可获得2．3～3．6模数的水玻璃产品。高脱硅率有利于PRHA的多孔性形成。在NaOH溶液浓度2mol／L和溶煮时间2h条件下，RHA转化为模数3．3的水玻璃和DRHA，SiO2溶出率达到94.83％。活化DRHA制备PRHA的最佳工艺为：硫酸质量分数5％、活化时间4h、活化温度90℃。PRHA对中性大豆毛油的脱色能力是目前植物油工业中常用的活性凹凸棒石粘土的3倍。     

国外国有林管理体制与产权变革及对我国的启示

简要分析了欧美市场经济国家国有林的管理体制及其改革动向，然后重点对原苏联东欧等经济转轨国家的国有林管理体制改革及其经验教训进行了分析。在此基础上，分析了其对我国国有林管理的启示与政策含义。     

Land Cover Transition in Northern Tanzania

Land conversion in sub‐Saharan Africa has profound biophysical, ecological, political and social consequences for human well‐being and ecosystem services. Understanding the process of land cover changes and transitions is essential for good ecosystem management policy that would lead to improved agricultural production, human well‐being and ecosystems health. This study aimed to assess land cover transitions in a typical semi‐arid degraded agro‐ecosystems environment within the Pangani river basin in northern Tanzania. Three Landsat images spanning over 30 years were used to detect random and systematic patterns of land cover transition in a landscape dominated by crop and livestock farming. Results revealed that current land cover transition is driven by a systematic process of change dominated by the following: (i) transition from degraded land to sparse bushland (10·8%); (ii) conversion from sparse bushland to dense bushland in lowland areas (6·0%); (iii) conversion from bushland to forest (4·8%); and (iv) conversion from dense bushland to cropland in the highlands (4·5%). Agricultural lands under water harvesting technology adoption show a high degree of persistence (60–80%) between time slices. This suggests that there is a trend in land‐use change towards vegetation improvement in the catchment with a continuous increase in the adoption of water harvesting technologies for crop and livestock farming. This can be interpreted as a sign of agricultural intensification and vegetation regrowth in the catchment. Copyright © 2015 John Wiley & Sons, Ltd.