拟南芥VTE1过量表达可以增加维生素E含量和提高烟草植株耐盐行

维生素E在动物细胞内具有抗氧化等重要作用，但在植物体内的功能却鲜为人知．本实验利用CaMV 35S启动子与来源于拟南芥的编码生育酚环化酶（TC）的cDNA（VTE1）构建的嵌合表达载体，以根癌农杆菌介导的叶盘法转化烟草W38．实验结果表明，具有卡那霉素抗性的再生植株经RT-PCR检测，得到了与阳性对照一致的495bp的目标片段；转基因植株的VE含量比对照植株高2倍左右，个别株系高达11倍．实验还发现，在耐盐性实验中转基因植株对盐的抗性明显高于野生型烟草；同时，在不同盐浓度（150、250mmoL／L）胁迫下转基因植株VE含量比未转化植株增加了1．3～1．8倍，首次证明VTE1与植物耐盐性之间的关系．     

基于CiteSpace的高校教师职业心理健康文献计量分析

为系统把握高校教师职业心理健康领域近10年的主要研究内容和研究方向,以中国知网(CNKI)作为数据源,经过2次检索得到2011—2020年10年间的文献,统计分析发文量,使用CiteSpace软件可视化处理,得到关键词共现图谱。结果表明:高校教师职业心理健康的相关研究主要集中于职业倦怠和职业压力,研究热点是成因和对策,重点研究对象为体育教师、青年教师、英语教师和女教师;通过内容分析发现,职业压力和职业倦怠均对高校教师职业心理健康存在消极影响;从社会、学校、个人3个层面有效干预可改善教师职业压力和职业倦怠,进而提升其心理健康。     

1种改进的流变模型在层状覆盖层坝基上的应用*

为了深入剖析深厚覆盖层中各层岩土体的流变性对大坝安全稳定的影响机理。探索新的流变元件模型H-KS以适应层状覆盖层坝基,借助Comsol建立数值模型,计算青湾坝安全稳定指标,分析坝基流变对大坝整体的影响。研究结果表明:对于岩性、物理力学性质差异较大的层状覆盖层坝基,采用H-KS流变模型能较好反应大坝应力、变形和渗流实际情况,与监测值对比,误差在5%以内;相比不考虑流变的模型而言,应力、变形分别增大了10%和15.7%,部分增量会影响大坝结构的安全稳定,应予以重视;流变导致大坝整体渗透性降低,粗细粒层孔隙水压力分别减小了约50%和2.5%,加速了流固耦合过程,对于重新评估大坝的渗透性有重要参考意义;由于流变性不同,深厚覆盖层中粗粒土层在变形、应力和渗流方面影响最大,细粒土的贡献相对较小,除了与岩性相关之外,还与土层所处位置、厚度等相关。研究结果可为层状覆盖层上的大坝安全稳定体系的建立提供理论支持。     

高应力条件下尾矿破碎特性及坝体稳定性研究*

高应力条件下尾矿破碎特性与坝体稳定性研究是高尾矿坝避免溃坝事故的重要参考。分析尾矿颗粒破碎过程中级配曲线的演化规律,提出采用BET测试颗粒比表面积以定量化表征颗粒破碎指标;在室内高应力三轴试验的基础上,阐述高应力条件下尾矿的力学行为,提出高应力条件下尾矿强度准则,并基于该准则对工程实例进行应用分析。结果表明:相比于常用破碎指标,从能量观点出发的BET法比表面积表征尾矿颗粒破碎更为合理;采用线性Mohr-Coulomb准则计算尾矿在低应力阶段的内摩擦角,采用幂函数Mohr强度准则计算尾矿在高应力阶段的内摩擦角;提出1套考虑高应力条件下尾矿强度折减的坝体稳定性分析方法,以供实际工程参考。     

双金属复合管线应力分析中当量折算模型的建立与应用*

针对目前高腐蚀性气田的集输系统管线应力分析标准中,未给出双金属复合管线的强度校核方法,依据当量折算理论,将双金属复合管的几何与材料特性转化为等效单层管,通过有限元法验证双层管与等效管模型的计算精度。研究结果表明:利用当量折算理论,可以快速将双金属管外径、壁厚、弹性模量、热膨胀系数、密度等参数等效转化为单层管道相关参数。经实际应用检验,该方法在解决工程问题时具备一定的实用性与准确性;双金属复合管系统当量折算模型具备计算方便和精度高等优点,该模型可用于双金属复合管线结构设计和强度校核。研究结果可为双金属复合管线的强度校核提供1种参考方法。     

五氯酚胁迫对转基因杨树光合光响应特性的影响

以从美国引入的转基因杨树(Populus deltoides×nigra,DN34)为材料,设置0、50、100 mg·kg~(-1)三个五氯酚胁迫质量分数开展温室盆栽试验,利用Li-6400便携式光合作用测量系统研究五氯酚污染胁迫下转基因杨树对光强的生理响应.结果表明:与对照相比,相同光强下50和100 mg·kg~(-1)质量分数的五氯酚胁迫均降低了转基因杨树叶片的净光合速率(P_n)、蒸腾速率(T_r)、胞间CO_2摩尔分数(C_i)和气孔导度(G_s).因此高质量分数五氯酚比低质量分数五氯酚对转基因杨树光合作用产生更大的抑制响应.     

热休克、Poly I:C上调草鱼GRP78基因表达

葡萄糖调节蛋白78(GRP78)是细胞内一种应急蛋白,它通过对细胞内、外胁迫因子产生强烈的应答而调节内质网稳态.草鱼(Ctenopharyngodon idellus)GRP78克隆于草鱼肝肾cDNA文库,全长2 490 bp.其中,5'非编码区为155 bp,含有7个热休克元件,3'非编码区为373 bp,最大开放阅读框为1 962 bp,编码653个氨基酸.序列分析表明,草鱼GRP78的N端包含3个HSP70家族的签名序列,C末端为内质网蛋白滞留信号KDEL,草鱼GRP78与人及其它动物的同源性很高.适应性进化分析也显示GRP78非常保守,受到强烈的功能约束,说明该蛋白质在进化中非常重要.RT-PCR分析表明,相对于本底水平,34℃热激和Poly I:c诱导后,草鱼GRP78在肝、肾等组织巾的表达明显上调.图4表1参16     

螺旋式旋流器的切向速度分析

借助CFD软件,采用RSM模型对螺旋式旋流器内的切向速度场进行了数值模拟。模拟结果表明:旋流器内部的流场分为螺旋通道内的准自由涡和内筒区域的准强制涡;在柱锥交界区域的内筒外壁附近有一低速区,易导致颗粒富集而出现高浓度区进而影响分离效率;此外通过改变入口速度和螺旋通道的螺距,研究对旋流器切向速度的影响。通过对流场特性的研究,为进一步充分认识此类旋流器的分离机理提供了依据。     

Soil amendments and cultivar selection can improve rice yield in salt-influenced (tsunami-affected) paddy fields in Sri Lanka

The tsunami disaster in the Indian Ocean in December 2004 caused devastation of agricultural soils by salt water over wide areas. Many rice fields located close to the coast were affected by the flood of seawater. Electric conductivity (EC) of soils in tsunami-affected rice fields was found to be higher compared to unaffected fields 2 years after the tsunami. Four soil amendments (gypsum, dolomite, cinnamon ash and rice-husk-charcoal) were tested for their influence on improving the yield parameters of rice grown in a tsunami-affected and a non-affected area. Yield parameters were compared with an untreated control of the same cultivar (AT362) and with a salt resistant rice variety (AT354). The salt resistant variety had the highest grain yield. The two amendments gypsum and rice-husk-charcoal led to an increase in grain yield compared to the untreated control, whereas dolomite and cinnamon ash had no significant effect on grain yield.     

Assessment of GM Crops in Commercial Agriculture

The caliber of recent discourse regarding geneticallymodified organisms (GMOs) has suffered from a lack of consensuson terminology, from the scarcity of evidence upon which toassess risk to health and to the environment, and from valuedifferences between proponents and opponents of GMOs. Towardsaddressing these issues, we present the thesis that GM should bedefined as the forcible insertion of DNA into a host genome,irrespective of the source of the DNA, and exclusive ofconventional or mutation breeding.Some defenders of the commercial use of GMOs have referred to thescientific work of GMO critics as ``junk science.' Such a claim isfalse and misleading, given that many papers critical of both theutility and safety of GMOs have been published in peer reviewedjournals by respected scientists. In contrast, there is a dearthof peer reviewed work to substantiate the frequently heardassertions of either safety or utility in GMOs. The polarity,which now characterizes much of the public discourse on GMOs,reflects not simply scientific disagreement, but alsodisagreement in underlying value assumptions. Value differencesstrongly affect the assessment of both benefit and harm fromGMOs.The concept of substantial equivalence occupies a pivotalposition in the GMO risk assessment process that is used in bothCanada and the US. A GMO judged to be substantially equivalent toa conventional product – as have all submissions to date – ispresumed to be safe enough for commercialization. The conclusionof safety – from both human health and environmental perspectives– should be based on scientific evidence, corroborated by actualexperimentation. However, regulators infer safety largely fromassumptions-based reasoning, with little or no experimentalvalidation. The judgement of safety because of substantialequivalence is a dubious argument by analogy.