Cucumis sativus is an important vegetable crop in the world. Agrobacterium mediated transgenic technology is an important means to study plant gene function and variety improvement. In order to further accelerate the transgenic research and breeding process of cucumber, aiming at the Agrobacterium mediated genetic transformation method of cucumber, this paper expounds the research progress and existing problems of Agrobacterium mediated transgenic cucumber from the aspects of influencing factors of cucumber regeneration ability, genetic transformation conditions and various added substances in the process, and prospects the future of improving the efficiency of cucumber genetic transformation and the application of safety screening markers, in order to provide reference for cucumber stress resistance breeding and fruit quality improvement.
Two kinds of solar thermal power generation systems (trough and tower) are selected as the research objects. The life cycle assessment (LCA) method is used to make a systematic and comprehensive environmental impact assessment on the trough and tower solar thermal power generation. This paper mainly analyzes the three stages of materials, production and transportation of two kinds of solar thermal power generation, calculates the unit energy consumption and environmental impact of the three stages respectively, and compares the analysis results of the two systems. At the same time, Rankine cycle is used to compare the thermal efficiency of the two systems.
Distributed biomass energy technology has strong adaptability to the types of raw materials, flexible project scale, can meet the needs of special users, better economy in small scale, easier commercial development, in line with the characteristics of biomass resources and China’s national conditions. The distributed utilization of biomass energy mainly includes biomass briquette fuel and biogas. The key technologies include biomass briquette fuel processing and combustion, large and medium-sized biogas engineering technology, biomass gasification pyrolysis and gas utilization. At present, China’s distributed biomass energy technology is mainly in the stage of technological improvement and application demonstration. It is expected that by 2030, most of the key technologies will be basically mature and have the conditions for industrialization. The main development direction of China’s distributed biomass energy industry is the replacement of traditional coal-fired gas, urban/rural clean living energy supply, and rural ecological environmental protection. The pollution caused by burning coal/fuel oil, and at the same time centering on the national new urbanization strategy, provide sustainable clean energy for the construction of new rural areas, and improve the level of rural ecological and environmental protection. At present, the main bottleneck restricting the development of distributed biomass energy industry is economy and reliability. The state should increase investment in technological innovation and policy support, convert the environmental and social benefits of biomass energy into cost benefits, and promote biomass energy. The development of the industry can be distributed and utilized.
Metal organic framework is a class of hybrid network of supramolecular solid materials comprised of a large number of inorganic and organic linkers all bounded to metal ions in a well-organized fashion. This type of compounds possess a greater surface area with an advantage of changing pore sizes, diversified and beautiful structure which withdrew an intense interest in this field. In the present review articles, the structural aspects, classification, methods of synthesis, various factors affecting the synthesis and stability, properties and applications have been discussed. Recent advances in the field and new directions to explore the future scope and applications of MOFs have been incorporated in this article to provide current status of the field.
The analysis of the accumulation and export of nutrients by the cowpea crop is fundamental for a more sustainable fertilization program, because the definition of the doses of organic fertilizers based only on the estimated maximum yield does not guarantee the maintenance of soil fertility. The objective of this study was to evaluate the effect of fertilization with chicken manure on the productivity, accumulation and exportation of nutrients by the pods of cowpea. A randomized block design was used, with five doses of chicken manure (0; 5; 10; 20 and 40 t ha-1) and four repetitions. The highest levels of P and Mg were found in the leaves with the application of 40 t ha-1 of manure. The maximum pod length was 14.47 cm, estimated with the dose of 33.33 t ha-1 of manure. The highest values of diameter, number of pods per plant and pod productivity were observed at the highest dose of manure applied. In relative terms, that is, total exported in relation to the total extracted by the aerial part, phosphorus is the nutrient most exported by the pods, on average 58%, followed by N (55%), K (43%), Mg (40%), S (38%) and Ca (17%). At the highest dose, although Ca accumulation occurred in large quantities (31.3 kg ha-1), only 13% of it was exported by the pods. Fertilizing cowpea with chicken manure supplied essential nutrients and increased pod yield from 7.2 (no fertilization) to 16.3 t ha-1 (fertilization with 40 t ha-1 of chicken manure). The plant remains of the cowpea constitute an important source of nutrients, being obtained at the highest dose of manure applied (40 t ha-1) the following amounts of macronutrients (kg ha-1): N (51.4); P (5.1); K (27.6); Ca (27.1); Mg (8.2); S (5.1), which may return to the soil, with the incorporation of the plants.
The rare earth mining area in South China is the main production base of ionic rare earth in the world, which has brought inestimable economic value to the local area and even the whole nation. However, due to the lack of mining technology and excessive pursuit for economic profits, a series of environmental problems have arisen, which is a great threat to the ecosystem of the mining area. Taking Lingbei rare earth mining area in Ganzhou as an example, this paper discriminated and analyzed such aspects as the ecological source, ecological corridor and ecological nodes of the mining area based on the landscape ecological security pattern theory and the minimum cumulative resistance model (MCR) method, and constructed a landscape ecological security pattern of the mining area during the 2009, 2013 and 2018. The results show that: i) The patch area of the ecological source of rare earth mining area is small, mainly concentrated in the east and west sides of the mining area. ii) During the selected year, the ecological source area, ecological corridors, radiation channels and the number of ecological nodes in the rare earth mining area are increasing, indicating that the landscape ecological security of the rare earth mining area has been improved to some extent, but it remains necessary for relevant departments to make a optimized planning to further reconstruct the ecological security pattern of the rare earth mining area.
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