垃圾填埋场中真细菌群落16S rRNA基因的分析

回灌式垃圾填埋场渗滤液中真细菌群落的多样性同样通过不依赖于微生物培养的分析而获得。利用特异性的引物对,选择性地扩增渗滤液DNA中的真细菌16S rRNA基因片断(16S rDNA),并用于构建16S rDNA克隆文库。文库内真细菌16S rDNA的遗传多样性通过限制片断长度多态性分析(RFLP,限制性内切酶Hin PII和Msp I)而获得。初步的结果表明,随机选出的200个真细菌克隆子被分为147个不同的RFLP型(组),当中丰度最高的两个型均仅含有9个克隆子,两者共占所有被分析克隆子的不到10%;克隆子数≥2的型共有21个(包括以上2个丰度最高的型),它们共代表74个克隆子,占所有被分析克隆子的37%;而剩下的126个型均只含有1个克隆子,它们共占整个基因文库的63%。由此可见,李坑垃圾渗滤液中的真细菌具有非常复杂的群落结构。     

非离子表面活性剂对污泥调理脱水效果的影响

现有污泥脱水技术仅使污泥含水率降到80%左右,难以满足日益严格的污泥处置要求.以污泥比阻（SRF）、脱水率为考察指标,比较了两大类非离子型表面活性剂（辛基酚聚氧乙烯醚OPEO型和烷基糖苷APG）对剩余污泥的脱水效果,并对原泥及调理后污泥进行了显微观察.结果表明,非离子表面活性剂可使污泥絮体粒径变小,不规则程度降低,改善了污泥的脱水性能,而且烷基糖苷APG脱水效果优于OPEO型.APG投加量为0.05%干固体时,污泥比阻即可降低到原泥的42%,脱水率可达到93%.以烷基糖苷APG为调理剂进行板框脱水实验,结果表明,当APG投加量为0.05%干固体时,脱水泥饼含水率比原泥脱水泥饼含水率低约10%,脱水率可达到97%.本研究为APG应用于污泥脱水,改善污泥脱水性能提供一些参考.     

Coupling effects of the explosion shock wave and heat radiation on the dynamic response of a fixed-roof tank

The occurrence of leakage in large tank farms or oil deposits can lead to fire or explosion accidents. Coupling effects of fire and explosion loadings can cause considerably more damage to adjacent tanks or buildings than either loading individually does. In this study, the combined loadings of the explosion shock wave and heat radiation from a pool fire on a neighboring empty fixed-roof tank were numerically investigated. The effects of the explosion shock wave intensity and relative height of the explosion center [the ratio of the height of the explosion center to the height of the tank (h_r)] were analyzed. The results indicate that tanks damaged by explosion shock waves have decreased fire resistance and critical buckling temperature. Moreover, the thermal buckling deformation of the predamaged tank largely depends on the explosion shock wave. With an increase in the explosion shock wave intensity or a decrease in h_r, the explosion shock wave has greater influence on the fire resistance of the tank, and the critical buckling temperature decreases. This paper can provide an understanding of the dynamics of a tank under explosion shock wave loading, and of the critical failure criterion and failure modes of a target tank under the coupled loading of the explosion shock wave and an adjacent pool fire.     

电力配电房在火灾下的有限元模拟分析

针对钢框架结构形式的电力配电房在基本荷载组合工况下构件承载能力的关键问题,运用ABAQUS有限元分析软件对模型进行空间静力分析,得出电力配电房在各种工况下的最不利荷载及其位置;针对电力配电房在火灾工况下构件耐火性能的关键问题,运用ABAQUS模拟分析其在火灾工况下的温度场分布和钢框架结构的承载能力和力学性能,并对这两类工况对比分析。研究结果表明:在基本荷载工况下,电力配电房在恒荷载与活荷载形成的组合效应下产生的沿X、Y、Z方向的剪力和弯矩最大,且其形成的竖向位移也最大;在火灾工况下,电力配电房最大应力位置与普通荷载工况大致相同,但最大位移位置不同;虽有局部钢材应力超限,但钢框架结构仍具备承载能力,设计人员可将应力超限的构件替换为屈服强度更高的钢材而非全部替换,既保证了整体结构的安全性,又达到节约材料降低造价的目的。     

氟碳涂层体系在我国水环境中防腐性能研究

通过现场曝露试验,获得氟碳涂层体系在我国淡水、海水和盐湖水环境中4年腐蚀结果,总结了它们的腐蚀行为。无论是在自然环境下的曝露试验,还是实验室条件下的盐雾试验和紫外光老化试验结果,都表明氟碳涂层具有优异的耐候性和耐水性;水气渗透性试验也表明氟碳涂层具有较低的渗水率;氟碳涂层虽具有低的表面能,但在淡水和海水环境中,其抗水生物附着性能仍不理想。     

Indigenous bacteria may interfere with the biocontrol of plant diseases

Prodigiosin is a reddish antibiotic pigment that plays an important role in the biocontrol of plant diseases by the bacterium Serratia marcescens. However, its activity is unstable under agricultural conditions; further, it can be degraded by various environmental factors. To examine the effect of epiphytic microbes on the stability of prodigiosin used for biological control processes, we collected a total of 1,280 bacterial isolates from the phylloplane of cyclamen and tomato plants. Approximately 72% of the bacterial strains isolated from the cyclamen plants and 66% of those isolated from the tomato plants grew on minimal agar medium containing 100 μg ml⁻¹ prodigiosin. Certain isolates obtained from both plant species exhibited prodigiosin-degrading activity. We compared the 16S rRNA gene sequences derived from the isolates with sequences in a database. The comparison revealed that the sequences determined for the prodigiosin-degrading isolates were homologous to those of the genera Pseudomonas, Caulobacter, Rhizobium, Sphingomonas, Janthinobacterium, Novosphingobium, and Rathayibacter. These results indicate that indigenous epiphytic microorganisms may interfere with the interaction between plant pathogens and biocontrol agents by degrading the antibiotics produced by the agents.     

低真空度下土工离心机产热机理试验研究

目的为1000 g以上的大型高速土工离心机提供散热方案,保证土工离心机的正常工作。方法通过试验研究和理论分析相结合的方法,研究低真空度下高速转子的产热机理,分析散热模式。结果绝对压力越高,离心室内的升温速度越快。不同真空度下(绝对压力10000、5000、3000、2000、1000 Pa),离心机驱动电机的输入功耗分别为2.17、3.79、5.17、7.66、11.56 kW。超重力高速土工离心机的产热主要由空气与高速转子的摩擦引起的第一热源,由高速旋转空气与离心舱壁面摩擦产生的第二热源,还有其他机构摩擦、空气与底部顶部摩擦产生的少量热源。结论第一热源产生的壁面热量可以通过设置冷却夹套快速带走,离心舱中心产生的第二热源的热量可以通过通入适量的冷风加以冷却,还可以通过注入冷却剂快速蒸发,利用汽化潜热进行快速冷却。     

飞机起落架材料防护技术现状及研究进展

介绍了飞机起落架高强度钢的防护工艺及其防护特点.传统的防护工艺主要是镀铬和镀镉工艺,目前出现了无氰镀镉-钛、高速火焰喷涂(HVOF)涂层、低氢脆刷镀镉等新型防护工艺.通过对各新型防护工艺与传统工艺的工艺性能及耐腐蚀性能进行对比发现,各新型防护工艺都能很好地取代传统的防护工艺应用于飞机起落架的保护.     

抗铅、镉菌株对土壤铅、镉生物有效性的影响

将从土壤中分离到的2株能同时耐铅(Pb)、镉(Cd)的抗性菌株(编号为H1和H2)分别接种至Pb、Cd污染的土壤中进行小白菜盆栽试验,研究2株抗性菌株对土壤Pb、Cd生物有效性的影响。结果表明:H1菌株可专一性的钝化交换态Cd,降幅为43.78%,并能显著促进小白菜地上部生长,与对照相比增产79.62%;H2菌可同时降低交换态Pb、Cd的比重,降幅分别为30.31%和27.61%,但小白菜产量与对照无显著差异。此外,与对照相比,接菌处理均能显著降低小白菜地上部Pb、Cd含量。     

电石渣和石灰对污泥的改性效果比较

在含水率为86.1%的脱水污泥中分别添加10%的电石渣和工业生石灰,其搅拌30min后及自然晾晒24,48,72,96,120 h后的含水率持续线性下降,自然晾晒120 h后可达到填埋标准;添加电石渣及石灰的污泥,其单位质量水分蒸发速率与原污泥有本质差异;两种改性剂均可使污泥比阻降低50%左右;经板框压滤机压滤出的泥饼...