Evaluation of the infectivity, gene and antigenicity persistence of rotaviruses by free chlorine disinfection

The effects of free chlorine disinfection of tap water and wastewater effluents on the infectivity, gene integrity and surface antigens of rotaviruses were evaluated by a bench-scale chlorine disinfection experiments. Plaque assays, integrated cell culture-quantitative RT-PCR (ICC-RT-qPCR), RT-qPCR, and enzyme-linked immunosorbent assays (ELISA), respectively, were used to assess the influence of the disinfectant on virus infectivity as well as genetic and antigenic integrity of simian rotavirus SA11 as a surrogate for human rotaviruses. The ICC-RT-qPCR was able to detect rotaviruses survival from chlorine disinfection at chlorine dose up to 20 mg/L (60 min contact), which suggested a required chlorine dose of 5 folds (from 1 to 5 mg/L) higher than that indicated by the plaque assay to achieve 1.8 log₁₀ reductions in tap water with 60 min exposing. The VP7 gene was more resistant than the infectivity and existed at chlorine dose up to 20 mg/L (60 min contact), while the antigencity was undetectable with chlorine dose more than 5 mg/L (60 min contact). The water quality also impacted the inactivation efficiencies, and rotaviruses have a relatively higher resistant in secondary effluents than in the tap water under the same chlorine disinfection treatments. This study indicated that rotaviruses have a higher infectivity, gene and antigencity resistance to chlorine than that previously indicated by plaque assay only, which seemed to underestimate the resistance of rotaviruses to chlorine and the risk of rotaviruses in environments. Present results also suggested that re-evaluation of resistance of other waterborne viruses after disinfections by more sensitive infectivity detection method (such as ICC-RT-qPCR) may be necessary, to determine the adequate disinfectant doses required for the inactivation of waterborne viruses.     

Preparation of Ti species coating hydrotalcite by chemical vapor deposition for photodegradation of azo dye

TiO_2 in anatase crystal phase is a very effective catalyst in the photocatalytic oxidation of organic compounds in water. To improve its photocatalytic activity, the Ti-coating Mg Al hydrotalcite(Ti–Mg Al–LDH) was prepared by chemical vapor deposition(CVD) method.Response surface method(RSM) was employed to evaluate the effect of Ti species coating parameters on the photocatalytic activity, which was found to be affected by the furnace temperature, N2 flow rate and influx time of precursor gas. Application of RSM successfully increased the photocatalytic efficiency of the Ti–Mg Al–LDH in methylene blue photodegradation under UV irradiation, leading to improved economy of the process.According to the results from X-ray diffraction, scanning electron microscopy, Brunner–Emmet–Teller and Barrett–Joyner–Hallender, thermogravimetric and differential thermal analysis, UV–vis diffuse reflectance spectra analyses, the Ti species(TiO_2or/and Ti~(4+)) were successfully coated on the Mg Al–LDH matrix. The Ti species on the surface of the Ti–Mg Al–LDH lead to a higher photocatalytic performance than commercial TiO_2-P25. The results suggested that CVD method provided a new approach for the industrial preparation of Ti-coating Mg Al–LDH material with good photocatalytic performances.     

Combined amendment reduces soil Cd availability and rice Cd accumulation in three consecutive rice planting seasons

The scientific application of stabilized materials has been considered an effective method for the in situ remediation of Cd-contaminated soil. This study aimed to investigate the persistence of the effect of a combined amendment of limestone and sepiolite(LS) on soil Cd availability and accumulation in rice grown in a mildly Cd-contaminated paddy field(0.45 mg/kg of Cd) over three consecutive rice seasons. 1125–4500 kg/ha of LS was applied to the soil before the first rice planting season and 5...     

东莞市景观生态演化特征的分析

利用多时相遥感手段,对东莞市的景观演化特征进行了回顾性分析,重点研究不同景观要素从1986～1994年的变化情况,探讨景观结构和功能变化与东莞市社会经济发展之间的对应关系。研究表明,高强度土地资源开发利用是东莞市景观变化的直接驱动因素,生物过程在景观动态变化过程中,居于次要地位;景观演化的基本格局是城市要素迅速膨胀,农业和自然要素则不断减少;由于缺乏必要的景观结构和功能的相互适应设计,在东莞市景观演化过程中,存在一些潜在的生态问题。初步探讨了东莞市景观生态保护的基本途径     

磁性纳米γ-Fe2O3/SiO2去除水中亚甲基蓝

以纳米γ-Fe₂O₃为磁性介质制备了磁性纳米γ-Fe₂O₃/SiO₂,并将其用于水中亚甲基蓝的吸附。表征结果显示：制备的γ-Fe₂O₃/SiO₂呈不规则核壳结构,平均粒径为38 nm,比表面积为74.35 m²/g,比饱和磁化强度为55 A·m²/kg。实验结果表明：γ-Fe₂O₃/SiO₂对亚甲基蓝的吸附适宜在中碱性条件下进行,4 h即可达吸附平衡;在初始亚甲基蓝质量浓度为180 mg/L、γ-Fe₂O₃/SiO₂加入量为2 g/L、初始溶液pH为7.0、吸附温度为298 K的条件下,吸附量最高为25.4 mg/g;共存金属离子会降低吸附效率,而少量的腐殖酸则会促进吸附;吸附过程符合准二级动力学方程,颗粒内扩散不是唯一的控速步骤;等温吸附满足Langmuir模型,该吸附是一个物理吸附过程;用乙醇洗涤的γ-Fe₂O₃/SiO₂重复使用4次时仍能保持约80%的原吸附量。     

三阶段控温堆肥过程中接种复合微生物菌群的变化规律研究

接种复合微生物是提高堆肥效率的主要方法之一,但由于堆料中土生微生物的竞争,较高浓度的土生微生物浓度会抑制接种微生物的长生繁殖.实验表明:当堆料中土生微生物初始浓度为4×10⁸CFU/g时,所接种的微生物不增殖,且随着堆肥的进行,浓度下降很快;而非接种微生物增殖很快,最高浓度可达10¹⁰CFU/g.当土生微生物浓度降低至4×10⁵个/g,接种微生物增殖较快,最高达10¹¹CFU/g.因此,本文利用堆肥自身产热和少许外来热源加热的三阶段控温法进行堆肥.使堆温在4 h内迅速升到70℃以上,并维持8 h,从而使土生微生物浓度降至4×10⁵个/g以下,并起到软化堆料,便于微生物降解的目的.待温度冷却至35℃～45℃时,接种复合微生物,使其快速生长繁殖,数量从10⁸ CFU/g上升到10¹¹CFU/g(干样品),且接种微生物以非接种做生物保持优势地位,从而快速分解垃圾中的有机物.由于在最终产品中含有大量接种有益微生物,可利用其作为菌肥进行回流接种堆肥,以增加堆料中接种微生物数目、改善堆肥微环境、节约菌剂用量、缩短堆肥发酵周期和降低堆肥成本.但利用接种微生物堆肥产品作为菌肥反复接种时,随着反复次数的增加,非接种微生物高浓度繁殖;接种微生物和非接种微生物浓度比约为1:3(反复接种5次),浓度情况发生了逆变.因此,回流菌肥反复接种5次后,接种菌剂基本上就不再起作用了.     

油茶籽饼粕有机脱毒及作猪饲料的营养价值

本文通过对油茶饼粕脱毒和营养成分的研究,结合含15%脱毒茶饼试验日粮作喂猪试验,得到当浸提次数 n=5次时,饼粕中皂素含量小于3%,喂猪的适口性好,且无毒理反应,脱毒茶饼中蛋白质含量达23.04%,可作为蛋白质饲料进行开发。     

长江中下游地下水中Cr,V,Co的形成及分布规律

以丰富的实际资源，论证了地下水中Ｃｒ、Ｖ、Ｃｏ元素的形成，含量及其分布规律，除了与地下水的含水介质成分有关外，主要爱乔石和氧化还原环境的控制。     

华北地区下古生界海相碳酸盐岩二次生烃作用机理研究

我国下古生界海相碳酸盐岩中有机质由于形成时间早，经历了漫长的地质历史演化，一部分有机质深埋已形成了烃类，由于后期构造运动抬升则停止了生烃过程，但当再次深埋时，源岩干酪根受热温度超过一次生烃温度时，源岩又开始第二次生烃。本文对我国古老的下古生界海相碳酸盐岩的二次生烃作用及其机理进行了较为详尽的研究。     

中低温厌氧处理城市污水污泥颗粒化的研究

用高径比为3∶1的UASB反应器分别在35℃和室温条件下处理模拟城市污水,研究了污泥的颗粒化过程。比较了在不同温度、浓度下形成的颗粒污泥的特征。水温为9~25℃,进水浓度为100~200 mg COD/L,水力上流速度(Vup)在0.013~0.11 m/h的4#UASB反应器在60 d内在形成了成熟的颗粒污泥。研究表明,进水中低的有机物浓度,低的Ca2+、Mg2+浓度和低的Vup没有抑制颗粒化进程。