作者机构:
[Wen, Shi-Zhi; Tang, Chun-Fang; Zhang, Ri-Qing; Li, Ke-Lin] College of Resource and Environment, Central South Forestry University, Changsha 410004, China;[Liu, Yun-Guo] College of Environmental Science and Engineering, Hunan University, Changsha 410082, China
通讯机构:
[Zhang, RQ ] ;Cent S Forestry Univ, Coll Resource & Environm, Changsha 410004, Peoples R China.
摘要:
The engineering application of natural hyperaccumulators in removing or inactivating metal pollutants from soil and surface water in field trials mostly presents the insurmountable shortcoming of low efficiency owing to their little biomass and slow growth. Based on further understanding of the molecular mechanism of metal uptake, translocation, and also the separation, identification, and cloning of some related functional genes, this article highlights and summarizes in detail the advances in research on transgenic techniques, such as Agrobacterium tumefaciens-mediated transformation and particle bombardment, in breeding of plants for metal resistance and accumulation, and points out that deepening the development of transgenic plants is one of the efficient approaches to improving phytoremediation efficiency of metal-contaminated environments. From the viewpoint of sustainable development, governments should strengthen support to the development of genetic engineering for metal resistance and accumulation in plants.
摘要:
Outbreaks of the migratory locust, Locusta migratoria L., occurred in the northwestern part of China. The processes leading to the outbreaks and successful control are described based on locusts collected in infested areas and information obtained from local experts and scientists. Swarms of adults landed on the grazing and farming lands of Jiminay County, Altay Prefecture, the Xingjian Uygur Autonomous Region in 2003 and 2004, and caused substantial damage to agricultural crops and pastures. In the spring of 2004, numerous nymphs that had developed black patterns appeared in Jiminay. They and migrants from the north were sprayed with insecticides during the period from July 20 to August 6, 2004. A total of 4,200 personnel were involved in this mission. As a result, further damage to crops and migration to other areas were prevented. Morphometric measurements indicated that the migrants had reached the body dimensions typical for gregarious forms.
摘要:
A close-looped process based on the membrane separation and electrolysis is proposed to regenerate the copper etchant in-situ, recover copper on-site and reuse it. It is characterized by selective separation of copper from the spent etchant, which is accomplished by the ion exchange membrane-electrowinning, and at the same time the other components useful for etching are reclaimed. The experiments show that at least 90% of electricity efficiency for copper removal can be maintained and the optimum condition for membrane-electrowinning is: cell voltage 2-2.5 V, operating temperature 40 - 50 degrees C and current density 500 - 1500 A/m(2). The regenerated etchant can be successfully reused to etch copper after adjusting its composition to the normal range, and its recycling property is as good as that of the fresh etchant after 50 times of use-disposal-regeneration cycles.
摘要:
The effects of photoperiod on nymphal growth and adult reproduction were investigated in a small cockroach, Margattea satsumana, living on the subtropical, Hachijo island (33degreesN), Japan. Nymphal development is slow under constant photoperiods at 25 degreesC. The shortest mean duration of nymphal development (176 days) is observed at LD 14 : 10 h, followed by LD 12 : 12 h (221 days) and LD 16 : 8 h (309 days). Nymphal development is further prolonged when the nymphs are transferred from LD 12 : 12 to LD 16 : 8 h at 90 days after hatching. However, rapid and synchronized development is observed when nymphs were transferred in the opposite direction. A decreased change in photoperiod from LD 14 : 10 to LD 12 : 12 h also reduces the duration of nymphal development, and this cannot be explained by the results obtained at constant photoperiods. Similarly, nymphs reared at LD 16 : 8 h during the first 60 days mature more rapidly when transferred to LD 12 : 12 h than when transferred to LD 14 : 10 h. The developmental suppression induced by long days may represent a form of summer diapause that is terminated rapidly by short days. Based on these observations and field-census data, it is suggested that this cockroach has a univoltine life cycle overwintering as nondiapause adults, and that this life cycle is stabilized by the response to changing photoperiod.
摘要:
A novel nickel stripper using ammonia as the key component was developed to substitute cyanide for removing nickel film from iron substrates. Its compositions are: ammonia 150 g/L, hydrogen peroxide 50 g/L, ammonium chloride 100 g/L, EDTA 7.5 g/L, copper chloride 15 g/L and glucopyrone 1.2 g/L. The optimum operating conditions are: pH 9.5 - 11, temperature 40 - 50 ℃ and stripping time 1 h. It shows many advantages over the traditional cyanide stripper including no toxicity, mild operation, lower cost, larger holding capacity, faster stripping rate and good protection for the base metal, and can meet the technical requirements in industry.