水工混凝土的常见病害及预防对策

在水利工程建设与运行实践中,水工混凝土经常受到裂缝、冻胀、冲磨、空蚀、碱骨料反应、碳化、溶蚀和侵蚀等病害的威胁,严重影响其耐久性。文章对水工混凝土的常见病害进行了分析,并从工程设计、施工原材料、施工工艺、运行管理等方面提出了相应的预防对策。

混凝土桥梁的化学检测与预防性养护

化学反应是物理病害出现的前提条件。只有在物理病害出现前做好化学指标的检测和不良化学反应的遏制,才能实现桥梁的预防性养护。文章分析了现行桥梁检测和养护工作的不足,提出了化学检测的必要性,并介绍了桥梁化学检测和预防性养护的方法与流程。

臭氧水对土壤微生物群落的影响

对设施蔬菜喷洒臭氧水来探究臭氧水对土壤微生物群落的影响.以喷洒清水和百菌清农药为对照,分别以低质量浓度(3 mg·L^(-1))、中浓度(6 mg·L^(-1))和高浓度(9 mg·L^(-1))的臭氧水对土壤进行喷洒.通过Mis Seq 2×300 bp高通量测序来分析了喷洒臭氧水对土壤微生物多样性的影响.结果表明:臭氧水不会改变微生物群落结构,对组成土壤微生物中的重要的微生物群落无伤害.

Effect of Silicon and Nitrogen Nutrition on Pest and Disease Intensity in Rice

Nutrition management is the most important for high yield production but it may affect the response of rice plants to pest and diseases due to the change of microclimate under rice plant canopy. The knowledge of nutrition management and its relation with pest and diseases are basis for setting up a high yield production system. Most of the pest and disease control procedures used by farmers can be considered as soil fertility management and these nutrition practices can have impact on the physiological susceptibility of crop plants to pest and diseases by affecting the plant resistance. Silicon content of plants is particularly effective against pest and diseases in rice and certain rice genotypes are more efficient accumulators of silicon, thus making them more resistant. In the absence of natural heritable resistance in rice varieties, resistance could be induced by altemate strategies to suppress certain pest and pathogens. Hence experiments were carried out in two stages during kharif 2010 and 2011 to assess the concentration of silicon in the index leaves of rice plant utilizing 133 varieties in four locations. The silica content of promising varieties ranged from 1.50% to 3.20%, 1.60% to 3.15%, 1.49% to 3.20% and 1.55% to 3.06% with a mean values of 2.50%, 2.48%, 2.51% and 2.43% at Jagtial, Warangal, Rajendranagar and Rudrur centres of Telangana region and not much variation in mean silica content in index leaves at different places. The overall yield from four locations ranged from 2,653 kg/ha to 6,860 kg/ha with a mean of 5,624 kg/ha. The yields recorded at Jagtial, Warangal, Rajendranagar and Rudrur centres ranged from 2,886 to 7,198, 2,653 to 6,831, 2,653 to 6,860 and 4,399 to 5,950 kg/ha, respectively. The lowest mean yield 5,069 kg/ha was noticed at Rudrur and the highest yield 5,940 kg/ha was found at Warangal. The variations in yields might be due to genotypic variations and also due to variations in climatic conditions of different locations.

Pest Management in Museum Collections and Storage Areas （New ApproachmOnline Sensors for Pest Detection）

Common denominator and one of the goals in the ＂storage＂ of many, even different, commodities （agricultural, etc.） is their protection against invasion by biological pests; protection of objects of cultural heritage deposited in museums, galleries, archives and other institutions of a similar type is one of the specific case. The present article is an overview of basic （potential） biological pests of some ＂storage＂ commodities （with emphasis on the protection of objects of cultural heritage） as well as methods used for their detection. In the final section, a modular system of the ongoing assessment of the environmental characteristics of depositaries and exhibitions （including ＂biological＂） is briefly presented; its advantage is the possibility of on-line monitoring of the evaluated parameters （temperature, humidity, lighting, etc.） including the detection of presence of crawling and airborne insects.

A STAGE-STRUCTURED SI ECO-EPIDEMIOLOGICAL MODEL WITH TIME DELAY AND IMPULSIVE CONTROLLING

This paper formulates a robust stage-structured SI eco-epidemiological model with periodic constant pulse releasing of infectious pests with pathogens. The authors show that the conditions for global attractivity of the ＇pest-eradication＇ periodic solution and permanence of the system depend on time delay, hence, the authors call it ＂profitless＂. Further, the authors present a pest management strategy in which the pest population is kept under the economic threshold level （ETL） when the pest population is uniformly persistent. By numerical analysis, the authors also show that constant maturation time delay for the susceptible pests and pulse releasing of the infectious pests can bring obvious effects on the dynamics of system.

Forest Bio-disaster Status and its Basic Research in China

This review outlines the characteristics and de- velopmental trends of forest bio-disasters (including disease, insect and rodent pests) of recent years in China, summarizes the achievements of the basic researches supported by the National Natural Sci- ence Foundation of China, defines the main draw- backs, and proposes some important issues to be highlighted in the basic research in the future in order to integrate research resources, concentrate re- search objectives and to accelerate the develop- ment of forest bio-disaster basic research in China .

Nine Pathogenic Fungi of Waterhyacinth Isolated in China

The native pathogens of waterhyacinth in China, were studied and compared on pathogenicity by Koch＇s postulate. Nine pathogenic fungi, YBH, YBB, YB, YYX, YY, YBA1, YBA2, YBA3 and YYB12, were isolated from diseased waterhyacinth plants, and collected from Zhejiang province and Shanghai. According to cultural characteristics, the nine isolates were preliminarily identified. Isolates YBH and YBB were Collectotrichum sp.; YB, YYX and YY were placed in fungi imperfecti; the isolates YBA1, YBA2, YBA3 and YYB12 were Alternaria sp. The isolate YBH was the highly virulent with a disease index （DI） of 65.28% after one month inoculation. The isolate YBA3 was equily virulent, with the disease index of 6770 after 7 day introduction. These two pathogens appear to have the potential as biocontrol agents and they deserve further study.