An Analysis to the Driving Forces for Water and Salt Absorption in Roots of Maize Seedlings Under Salt Stress

When maize seedlings were subjected to salt stress,a decline in root xylem pressure was observed within seconds,followed by a gradual increase in Na＋ deposition in the seedlings.The magnitude of xylem pressure response was positively correlated with,but not proportional to the intensity of the stress.A continuous recording of the xylem pressure profile showed that self-regulation of the xylem pressure existed before and after the imposition of salt stress when the environmental conditions were relatively stable.The salt induced increase in xylem tension dominated the total water potential of the plant when the salt stress was mild,but the osmotic potential became more prominent when the NaCl concentration in the root bathing solution was raised to over 100 mol m-3.The average transpiration rate of the seedlings dropped by 40% when the NaCl concentration in the root ambient was increased to 150 mol m-3.Although salt stress resulted in the decline of both the xylem pressure potential and the osmotic potential in the root xylem,the changes in the total water potential of the root xylem solution were always smaller than the changes in the water （osmotic） potentials of the solution bathing the root.An analysis to the water relations of maize seedlings showed that not only the water potential components,but the radial reflection coefficient of the roots was also dependent on the level of salinity.When the NaCl level in the root bathing solution was raised from 25 to 150 mol m-3,the radial reflection coefficient of the root declined from 0.43 to 0.31.This small change resulted in a remarkable increase in the normalised relative NaCl absorption by 2.4 times,indicating that the radial reflection coefficient of root played a very important role in regulating the absorption of NaCl in maize seedlings under salt stress.     

我国高校办学特色研究的现状与反思

近年来,我国高校办学特色研究主要集中在办学特色的意义建构、办学特色的影响因素以及办学特色的构建策略等方面。今后需重视高校办学定位研究,加强高校办学特色形成机制研究,注重高校办学特色跨学科整合性研究,倡导高校办学特色的元研究,突出高校办学特色实践取向研究。     

Husbandry stress exacerbates mycobacterial infections in adult zebrafish, Danio rerio (Hamilton)

Mycobacteria are significant pathogens of laboratory zebrafish, Danio rerio (Hamilton). Stress is often implicated in clinical disease and morbidity associated with mycobacterial infections but has yet to be examined with zebrafish. The aim of this study was to examine the effects of husbandry stressors on zebrafish infected with mycobacteria. Adult zebrafish were exposed to Mycobacterium marinum or Mycobacterium chelonae , two species that have been associated with disease in zebrafish. Infected fish and controls were then subjected to chronic crowding and handling stressors and examined over an 8-week period. Whole-body cortisol was significantly elevated in stressed fish compared to non-stressed fish. Fish infected with M. marinum ATCC 927 and subjected to husbandry stressors had 14% cumulative mortality while no mortality occurred among infected fish not subjected to husbandry stressors. Stressed fish, infected with M. chelonae H1E2 from zebrafish, were 15-fold more likely to be infected than non-stressed fish at week 8 post-injection. Sub-acute, diffuse infections were more common among stressed fish infected with M. marinum or M. chelonae than non-stressed fish. This is the first study to demonstrate an effect of stress and elevated cortisol on the morbidity, prevalence, clinical disease and histological presentation associated with mycobacterial infections in zebrafish. Minimizing husbandry stress may be effective at reducing the severity of outbreaks of clinical mycobacteriosis in zebrafish facilities.     

镇海石化成品可溶性物质对海洋环境的影响预测

本文采用Joseph-Sendner扩散模型,以龙海市镇海石化成品油罐区项目为例,对分散于水中可溶性物质对海洋水环境的影响进行预测、分析。在介绍Joseph-Sendner扩散模型的基础上,主要预测溶解油品、苯酚等可溶性物质以及施工挖泥产生的悬浮泥沙泄溢入海后的扩散、迁移变化状况以及影响范围,从而分析、探讨了分散于水中可溶性物质对海洋水环境的污染程度。     

对当前征占用林地管理主要问题之反思

根据全国连清资料,我国每年有林地转变为非林地的面积为56.2万hm2,目前我国林地管理存在着管理部门之间关系混乱、行政干预严重、林业部门自身执法犯法问题突出等问题。分析了造成这些问题的原因,提出了建立健全法制、理顺管理关系、加大案件查处力度、加强执法队伍建设、加大舆论宣传等对策。     

用主成分回归和偏最小二乘法定量测定谷物成分

用主成分回归和偏最小二乘方法分别处理谷物的付立叶变换近红外漫反射光谱,对谷物中含量分别为 10~(-1)的蛋白质、10~(-2)的脂肪、10~(-3)的赖氨酸进行了定量测定。表明这2种方法与经典化学方法没有系统偏差,结果优于逐步回归分析。     

Magnetic resonance imaging features of canine gliomatosis cerebri

A retrospective, case series study was undertaken to identify magnetic resonance imaging (MRI) characteristics of gliomatosis cerebri in dogs. Fourteen dogs were included by review of histopathological records and contemporaneous MRI. On MRI, all lesions presented as ill‐defined, intraaxial lesions within the left and right forebrain hemispheres with involvement of white and gray matter. Lesions presented as hyperintense areas on T2‐weighted and FLAIR sequences and as hypointense or isointense areas on T1‐weighted images, with mild parenchymal contrast enhancement in three dogs. Signal changes were noted in three to 10 cerebral lobes. Other most commonly affected structures were the thalamus (13), caudate nucleus (13), interthalamic adhesion (11), hypothalamus (11), callosal commissure (10), hippocampus (9), and quadrigeminal plate (8). Abnormalities within the caudal fossa were noted in 10 dogs. Solid tumor portions were identified in five dogs. The histopathological examination demonstrated in all dogs a widespread diffuse infiltration with neoplastic glial cells in white and gray matter with meningeal infiltration. Comparison between MRI and histopathology showed that all areas with signal changes on MRI corresponded to diffuse and dense infiltration with neoplastic cells. The signal intensity on T2‐weighted and FLAIR images reflected the density of neoplastic cells. In all dogs, MRI underestimated lesion extent and meningeal infiltration. Involvement of the caudal fossa was not seen on MRI in three dogs. Despite this, MRI allowed identification of lesions extending into at least three cerebral lobes and therefore satisfying the criteria used for diagnosis of diffuse glioma with gliomatosis cerebri growth pattern in humans.     

依法申请行政强制执行兽药案的思考

2017年,甘肃省夏河县农牧林业局对一起经营假兽药的违法行为进行了依法立案查处。在行政处罚决定书送达后当事人拒不履行行政处罚决定义务,执法机关申请人民法院进行了强制执行,案件执行完毕。本文通过对案件来源、查处过程和申请强制执行情况进行了讨论,梳理了假兽药认定和违法所得核算的相关依据,明确了申请强制执行的业务流程,为切实加强农业行政处罚管理,严格落实行政处罚措施提供参考。     

大型泵站噪声与治理

虽然《泵站设计规范》对泵站电动机层的噪声作了明确的规定,但实际上泵站机组运行产生的噪声多数超出了规范的要求.针对南水北调东线泵站工程年运行时间长,如何减小设备运行的噪声,减小其对运行人员的不利影响的问题,在分析噪声源的基础上,进行分析研究,以采取有效的减噪措施.首先根据水泵机组噪声产生的原理,针对噪声特点,在设备设计和制造方面采取优化电磁回路设计、选用优质材料、提高加工工艺标准等措施,从源头减小噪声;其次,结合设备结构和布置的特点,对主要噪声源——电动机和叶轮外壳采取阻尼隔音毡的措施,减小噪声的发射;最后在设备布置的空间内设置吸音材料,构建吸音空间等措施.多种减噪措施的组合,使泵站运行时电动机层的噪声小于85 dB,优于国家有关噪声的规范要求,改善了运行管理人员的工作环境.