苏子提取物对高脂血症大鼠模型血脂水平的影响

采用高脂饮食法建立大鼠高脂血症模型,分别测定正常对照组、高脂模型组、苏子提取物低剂量组(0.1 g/mL)、中剂量组(0.5 g/ml)、高剂量组(1.0 g/mL)血清中的TC、TG、LDL-C、HDL-C含量,研究苏子提取物(EPS)对大鼠模型高脂血症血清血脂水平的影响。结果表明,EPS能显著降低大鼠血清中的TC、TG、LDL-C水平,提高血清中HDL-C的含量,提示EPS具有一定的调节血脂作用。     

Physics and hydraulics of the rhizosphere network

Take home message Mucilage secreted by roots and EPS produced by microorganisms alter the physical properties of the soil solution and impact the water dynamics in the rhizosphere. The high viscosity of mucilage and EPS is responsible for the formation of thin filaments and interconnected thin lamellae that span throughout the soil matrix maintaining the continuity of the liquid phase across the pore space even during severe drying. The impact of these mechanisms on plant and microorganisms needs to be explored.     

噻枯唑对水稻白叶枯病菌作用机制研究初报

 透射电镜观察,噻枯唑在离体条件下能使水稻白叶枯病菌菌体内形成许多颗粒状物质,并出现大的空泡结构。噻枯唑在浓度较低时能刺激菌体的呼吸作用,对菌体胞外多糖的产生有抑制作用,但对菌体胞外水解酶的活性没有影响。噻枯唑能和金属Cu⁺⁺形成螯合物,但这种螯合作用没有改变噻枯唑的抑菌活性。     

Bacterial induction of the accumulation of phaseollin,pisatin and rishitin and their antibacterial activity

Bean hypocotyls, pea pods and tomato fruits were tested for phaseollin, pisatin and rishitin production when challenged with the phytopathogenic bacteriaErwinia carotovora, Pseudomonas phaseolicola, P. pisi andP. solanacearum, and their isolated extracellular polysaccharides. All bacteria induced phytoalexin accumulation, whereas only phaseollin and pisatin, but not rishitin, were elicited by EPS. The inhibitory effect of these three phytoalexins on bacterial growth was studied in liquid medium; whereas phaseollin and pisatin strongly inhibited growth, only a slight inhibitory effect resulted from the presence of rishitin in the medium.Samenvatting Bonehypocotylen, erwtepeulen en tomatevruchten werden onderzocht op hun vermogen tot vorming van respectievelijk faseolline, pisatine en rishitine, na inoculatie met de fytopathogene bacteriënErwinia carotovora, Pseudomonas phaseolicola, P. pisi enP. solanacearum en na behandeling met oplossingen van hun extracellulaire polysacchariden (EPS). Alle bacteriesoorten induceerden fytoalexinevorming, terwijl hun EPS wel faseolline- en pisatine-, maar geen rishitinevorming induceerden. Faseolline en pisatine remden de groei van de bacteriën in vloeibaar medium sterk; rishitine daarentegen had slechts een geringe groeiremming tengevolge.     

膜脂流动性的研究方法──DSC,ESR与FP

在介绍差示扫描量热法、电子自旋共振及荧光探针３种物理方法的基本原理基础上,测定了二棕榈酰磷脂胆碱（ＤＰＰＣ）的相变温度,讨论了３种方法应用于研究细胞膜或膜脂流动性上的差异。     

基于有限元分析的EPS助力电机轴等效刚度确定

在建立电动助力转向系统数学模型时,各部件的特性参数对其性能影响很大;电动助力转向系统的助力电机通过蜗轮、蜗杆减速后实现对驾驶员助力,而蜗轮、蜗杆传动机构通过橡胶缓冲套支撑在轴承上,且蜗轮与蜗杆啮合属接触问题,用工程力学无法计算电机轴等效刚度,从而在产品开发阶段建立电机动力学模型时其等效扭转刚度很难确定,本文基于有限元法对该机构等效刚度计算方法进行了研究,该算法还可用于根据系统性能要求确定机构形状和尺寸。     

电动助力转向系统(EPS)电动机电流控制的研究

分析了电动助力转向系统比例控制电动机电流的方法,发现系统有振动。在此基础上,提出了对电动机电流进行微分补偿的改进措施,设计了比例加微分控制电动机电流的方法。分析结果证实,所设计的比例加微分控制电动机电流具有良好的性能。试验结果表明,提出的控制方法是有效的,对电动助力转向开发有指导意义。     

冰糖橙与枸橼C-05对溃疡病菌生长特性的影响

【目的】采用新的接种方式,比较冰糖橙与枸橼C-05叶片对溃疡病菌生长特性的的影响,探讨冰糖橙与枸橼C-05对溃疡病菌敏感度的差异性。【方法】将完全展开、颜色淡绿的冰糖橙与枸橼C-05叶片进行75%酒精和1% NaClO消毒并切割后,分别与溃疡病菌在离体条件下共培养,观察叶片在MT培养基（对照）、MT中间嵌入NYGA培养基（MA）中对溃疡病菌生长的影响;分别提取冰糖橙和枸橼C-05叶片的粗提液,并以25%、50%和75%的比例添加至MT培养基中,观察冰糖橙和枸橼C-05叶片提取液分别对溃疡病菌生长的影响;同时以不同比例的叶片粗提液添加至NYGB培养基中,观察冰糖橙与枸橼C-05叶片提取液分别对溃疡病菌胞外多糖含量的影响。【结果】Xac在培养冰糖橙叶片的MT培养基中生长迅速,接种1周后即出现Xac的增殖现象,菌斑直径均值比对照大0.5 mm;接种2周后菌斑直径均值为5.27 mm,几乎是对照的3倍;而2-3周为Xac的急速生长期,菌斑直径由5.27 mm快速增长至13.41 mm,是对照菌斑直径的5倍多;3周后菌斑生长缓慢趋于平稳;各个时间点的菌斑直径与对照相比均达到极显著差异水平。在培养冰糖橙叶片的MA培养基中,Xac生长1 d后菌斑直径均值为4.58 mm,小于对照的6.19 mm;接种3 d后Xac继续生长,菌斑直径几乎与对照组相同,差异不显著;但是在接种5 d后,菌斑直径快速增长至21.31 mm,大于对照组的16.33 mm,3个菌斑长势连在一起,两者差异达到极显著水平。冰糖橙的叶片提取液对溃疡病菌的生长及胞外多糖含量均有促进作用,随着其添加浓度的增加,促进效果越明显,与对照相比均可达到极显著水平。Xac在培养枸橼C-05叶片的MT培养基中生长较为缓慢,在接种1周后菌斑直径与对照相比差异不显著;2周后菌斑直径约为对照的一半;3周时,菌斑直径均值为2.06 mm,小于对照的2.62 mm;2周和3周时的菌斑直径与对照相比均达到显著水平。在培养枸橼C-05叶片的MA培养基中,Xac生长较为缓慢,菌斑直径均小于对照组,在1、3和5 d时与对照相比均达到极显著水平。枸橼C-05的叶片提取液对溃疡病菌生长和胞外多糖含量的影响不大,与对照相比均差异不显著。【结论】冰糖橙叶片中存在可促进溃疡病菌的生长、增加胞外多糖含量的物质,这种物质可能突破了其自身免疫系统,导致其对Xac高度敏感而极易感病。枸橼C-05叶片与溃疡病菌共培养时,分泌抑制溃疡病菌生长的物质,使得枸橼C-05对Xac具有较低敏感度而表现抗性。     

料液上升流速对厌氧产氢颗粒污泥的影响

为研究水力因素对升流式厌氧污泥床(UASB)反应器产氢颗粒污泥的影响,通过内循环方式改变料液上升流速,探讨其对颗粒污泥性能和产氢效能的影响。结果表明,料液上升流速从0.15 m·h~(-1)增至0.6 m·h~(-1),颗粒污泥胞外聚合物(EPS)含量从99.48 mg·g~(-1)VSS增至214.51 mg·g~(-1)VSS,平均粒径从0.7 mm增至1.48 mm;松散附着的胞外聚合物(LB-EPS)在EPS中含量百分比减少,而紧密粘附的胞外聚合物(TB-EPS)含量百分比增加;颗粒污泥强度增大;产氢细菌相对丰度从59.52%增至66.45%;此过程产氢速率维持在16.08～17.04 L·d~(-1)。上升流速增至1.2 m·h~(-1),污泥沉降性能变差,产氢率显著降低。研究揭示水力因素对产氢颗粒污泥特性的影响,为UASB产氢反应器调控提供参考。     

Carbohydrates in cyanobacterial soil crusts as a source of carbon in the southwest Kalahari, Botswana

Semiarid ecosystems, also known as drylands, contain small amounts of carbon (C). To date only few studies have evaluated soil C dynamics in these ecosystems. Cyanobacterial soil crusts are considered a major source of organic C in semiarid ecosystems through photosynthesis, increasing soil organic C (SOC) pool as carbohydrates. This study considers cyanobacterial soil crusts as a source of C in the southwest Kalahari. Cyanobacterial soil crusts are well adapted to drylands because extracellular polysaccharide (EPS) secretions provide stabilization of soil and resistance to desiccation. The carbohydrate and chlorophyll a content were evaluated in the upper soil profile on Kalahari Sands and pan soils. Topsoil carbohydrate concentration decreased exponentially with depth. The carbohydrate content produced in cyanobacterial soil crusts in the southwest Kalahari represents up to 75% of the total SOC and is thus an essential component for the fertility of Kalahari Sand soils.