Preplanting indicators of survival and growth of desiccated Abies procera bareroot planting stock

Plant moisture loss during preplanting handling is considered one of the major elements in transplanting shock. The aim of the present study was to evaluate test parameters that may be suitable for assessment of the physiological condition of noble fir (Abies procera Rehd.) planting stock that has been subjected to desiccation stress. The transplanting-sensitive species was subjected to full exposure (roots and shoots) for 0, 0.5, 1.5, 3.0 and 6?h, or partial exposure (shoots) for 0, 3, 10, and 24?h before planting. The effects of desiccation on moisture content (MC), shoot water potential (ψ), root growth potential (RGP), root electrolyte leakage (REL), survival and height growth were evaluated. Desiccation effects on plant parameters and performance were generally significant after 1.5?h of full or 10?h of partial exposure to treatment. REL explained the largest percentage of performance variation in fully exposed plants, followed by MC and ψ. RGP tended to underestimate performance potential. Factors affecting the reliability of the test parameters, e.g. moisture loss rate, root rewetting and site conditions, are discussed.     

颗粒体积浓度对半开式叶轮离心泵泄漏涡和磨损的影响

固液两相流条件下半开式叶轮离心泵中颗粒冲击、泄漏涡发展和颗粒轨迹之间存在紧密交互作用,导致过流部件的磨损行为复杂多变。该研究结合双向耦合欧拉-拉格朗日方法和颗粒磨损Finnie模型,对不同颗粒体积浓度下半开式叶轮离心泵固液两相流场进行求解,分析了颗粒体积浓度对泄漏涡结构特征、颗粒运移轨迹和磨损特性的影响,揭示了颗粒体积浓度、叶顶间隙泄漏涡和过流部件表面磨损规律的关联机制。结果表明：随着颗粒体积浓度的增加,颗粒的频繁撞击加剧了叶片压力面进水边和后盖板磨损程度,叶片吸力面出水边的磨损范围向进水边方向延伸;颗粒体积浓度小于1%时,颗粒的轴向运动和叶顶间隙泄漏涡的阻碍作用导致颗粒易与叶片前缘靠近叶根处和吸力面出水边靠近叶顶的区域发生撞击,诱发严重磨损,且呈现点状磨损;当颗粒体积浓度大于3%时,叶轮后盖板的整体磨损强度大于叶片,颗粒体积浓度的增加造成流入叶顶间隙层的颗粒数增加,颗粒对叶顶间隙泄漏涡的冲击导致涡流的破碎、分离、再融合,加剧不稳定流动,泵的扬程和效率均明显下降。该研究可为固液两相半开式叶轮离心泵优化设计和安全稳定运行提供理论参考。     

Differential Sensitivity of Rice Cultivars to Salinity and Its Relation to Ion Accumulation and Root Tip Structure

Abstract

Effects of NaCl on the growth, ion content, root cap structure and Casparian band development were examined in four rice (Oryza sativa L.) cultivars with different salt resistance (salt-sensitive indica-type IR 24 and japonica-type Nipponbare and salt-resistant indica-type Nona Bokra and Pokkali). Experiments were conducted to find the differences in salinity resistance during early seedling and developed seedling stages among the cultivars. For salinity treatment, sodium chloride (NaCl) was added to nutrient solution at concentrations of 0, 25 and 50 mM for 7 days from germination to the 7th day (early seedling stage) or from the 7th day to 14th day (developed seedling stage). Growth inhibition by salinity was more prominent in the early seedling stage than in the developed seedling stage. Based on the growth, the order of the sensitivity was IR24 > Nipponbare > Nona Bokra > Pokkali. The growth of NaCl-treated rice cultivars relative to control was significantly and negatively correlated with the Na⁺ content and Na⁺/K⁺ ratio in roots and shoots in both stages. Scanning electron microscopic observation revealed that the root cap tissues proliferated and extended to the basal part of the root tip by salinity. The length of root cap was, however, reduced by 50 mM NaCl in sensitive cultivars due to peeling off. An endodermal Casparian band was formed in the basal region of the root tip. Development of the Casparian band was more prominent in sensitive cultivars than in tolerant cultivars. Root cap proliferation might be related to NaCl resistance in rice seedlings, but the Casparian band may not function efficiently in Na⁺ exclusion. Essentially the present results suggest that exclusion of Na⁺ from roots plays a critical role in expression of Na⁺ resistance in rice seedlings and the root cap is important for Na⁺ exclusion.     

七叶树与马褂木抗寒性比较分析

[目的]为七叶树、马褂木在北方推广应理论依据和有益参考.[方法]以七叶树、马褂木幼树1年生休眠枝条为材料,测定了不同冷冻处理条件下枝条的相对电导率和K＋相对渗出率,利用Logistic方程计算了各树种的半致死温度（LT50）,并通过苗木生长恢复试验进行了验证.[结果]随着处理温度的下降,七叶树、马褂木枝条的相对电导率和K＋相对渗出率均随处理温度的降低而呈“S”型上升,其枝条的LT50分别为-26.1 ～-27.3℃、-14.6～-15.2℃,与生长恢复试验的结果基本吻合.[结论]马褂木抗寒能力比七叶树低,推广应用时,应适当注意.     

Current experimental models,assessment and dietary modulations of intestinal permeability in broiler chickens

Maintaining and optimising the intestinal barrier (IB) function in poultry has important implications for the health and performance of the birds. As a key aspect of the IB, intestinal permeability (IP) is mainly controlled by complex junctional proteins called tight junction proteins (TJ) that link enterocytes together. The disruption of TJ is associated with increased gut leakage with possible subsequent implications for bacterial translocation, intestinal inflammation, compromised health and performance of the birds. Despite considerable data being available for other species, research on IP in broiler chickens and in general avian species is still an understudied topic. This paper reviews the available literature with a specific focus on IP in broiler chickens with consideration given to practical factors affecting the IP, current assessment methods, markers and nutritional modulation of IP. Several experimental models to induce gut leakage are discussed including pathogens, rye-based diets, feed deprivation and stress-inducing agents such as exogenous glucocorticoids and heat stress. Although various markers including fluorescein isothiocyanate dextran, expression of TJ and bacterial translocation have been widely utilized to study IP, recent studies have identified a number of excreta biomarkers to evaluate intestinal integrity, in particular non-invasive IP. Although the research on various nutrients and feed additives to potentially modulate IP is still at an early stage, the most promising outcomes are anticipated for probiotics, prebiotics, amino acids and those feed ingredients, nutrients and additives with anti-inflammatory properties. Considerable research gaps are identified for the mechanistic mode of action of various nutrients to influence IP under different experimental models. The modulation of IP through various strategies (i.e. nutritional manipulation of diet) may be regarded as a new frontier for disease prevention and improving the health and performance of poultry particularly in an antibiotic-free production system.     

Exogenous application of humic acid and salicylic acid to alleviate seedling drought stress in two corn (Zea mays L.) hybrids

Efficacy of 1?mM humic (HA) and salicylic (SC) acids on SC 260 and SC 705 corn seedlings to alleviate drought stress via polyethylene glycol was studied via hydroponics at Shiraz University, Iran in a factorial, randomized design, with four replicates each. Under stress, SC 260 had higher electrolyte leakage compared to SC 705, and exogenous application of HA combined with SA decreased SC 705 electrolyte leakage. As a general trend, photosynthetic pigment content, relative water content, root and shoot length, mean number and diameter of central and peripheral root metaxylem, and K⁺ accumulation were higher in SC 705 treated with HA and SA compared to SC 260. Application of HA with SA could be an effective and low cost approach to ensure seedling establishment and plant growth in fields affected by soil drought in the early season, especially for the SC 705 corn hybrid in semi-arid regions.     

玉米作为地质封存CO_2泄漏耐受植物的评估

二氧化碳的捕获与储存(CO2capture and storage,CCS)是全球CO_2减排最重要技术战略,其存在CO_2泄漏的风险,会对周围农田生态产生重要影响。深入认识植物对高浓度CO_2的响应并筛选对CO_2的耐受植物,为CCS项目区农业生产决策提供参考数据。本文设置玉米对不同CO_2浓度的响应情形,选择株高、鲜重、干重、净光合速率、蒸腾速率、气孔导度和胞间CO_2浓度作为玉米耐受的观测指标。结果表明,当CO_2浓度为10 000、20 000μmol/mol时,玉米株高增高7%～12%,生物量增加10%～15%,净光合速率增加高达60%左右;当CO_2浓度为40 000、80 000μmol/mol时,玉米株高度减少9%～12%,生物量减少10%～17%,净光合速率减少35%～45%左右。一定程度CO_2浓度的增加,对玉米生长发育具有"施肥"效应;在更高CO_2浓度下,会抑制其生长发育,并未出现植株死亡的现象。通过CO_2耐受指数法(LCTI)计算得出,玉米可以作为地质封存CO_2泄漏的耐受植物。     

管道泄漏分布式光纤监测时-空大数据分析方法

分布式光纤传感器能够灵敏地感知管道任意位置泄漏导致的局部温度变化,但是海量监测数据却具有显著的时-空非平稳性特征,难以直接根据监测数据进行泄漏诊断。在统计模式识别框架下,提出一种基于滑动窗口离群值分析的时-空大数据分析方法,仅利用分布式温度监测数据的内秉特征即可实现管道泄漏的智能化识别,确定了滑动窗口长度和异常状态诊断窗口长度的取值方法,并且进行了原型保温钢管泄漏监测的物理模拟。结果表明:在管道完好的状态下,该方法不会发生误报警的情况,而管道一旦发生泄漏,该方法能够快速识别管道泄漏事件,并对泄漏位置进行精准定位。该方法是一种无监督的人工智能大数据处理方法,在埋地管道泄漏监测中具有良好的应用前景。     

全球漏磁管道检测技术发明专利发展趋势

漏磁管道检测技术是一种应用较为广泛的无损检测技术。为了帮助中国企业了解更多的行业竞争态势,合理制定企业知识产权布局,对近年来漏磁检测技术相关专利信息进行了系统梳理。通过检索全球漏磁管道检测技术领域的专利信息,分析了漏磁管道检测技术在全球的专利布局情况和主要国家、主要申请人的专利布局策略。研究结果表明:近年来中国在漏磁管道检测技术方面的专利申请量和公开量增长迅猛,国外申请量保持平稳态势;国外主要申请人全部为企业,而中国主要申请人为高校、科研院所等,说明中国有大量研究成果尚停留在实验室阶段,有待实现产业应用。     

大型LNG储罐泄漏扩散研究进展

大型LNG 储罐一旦发生泄漏,将会对周边人员和财产构成重大威胁。基于充分调研,分别从理论、试验及数值模拟3 个方面论述了国内外关于LNG 泄漏扩散的研究进展,尤其是近年来国内外在数值模拟方面的突破性研究成果。大型LNG 储罐泄漏后的气体扩散理论模型主要有高斯模型、唯象模型、箱及相似模型、浅层模型;通过LNG 泄漏试验获取了大量基础数据,主要包括气象条件参数、气云、液池燃烧的相关数据;在数值模拟方面,对LNG 泄漏气云扩散开展了大量研究,尤其是针对不同影响因素耦合作用下LNG 的泄漏扩散演变过程、气云变化形态、影响区域、爆炸范围等进行了模拟分析。通过对比分析发现,数值模拟方法具有成本低、精度高、可操性强等优点,既能有效拓展理论和试验研究成果,又能开展复杂工况下LNG 泄漏扩散的研究。对3 种方法的研究趋势进行了预测,提出大型LNG 储罐泄漏扩散的研究还需与接收站实际情况相结合,指出在今后的研究中应以数值模拟研究为主、试验与理论研究为辅。