The methane(CH4) emissions from municipal solid waste(MSW) landfills in China in 2007 were estimated based on database of the three-dimensional emission factors matrix and point sources, by an IPCC recommended FOD(fir...The methane(CH4) emissions from municipal solid waste(MSW) landfills in China in 2007 were estimated based on database of the three-dimensional emission factors matrix and point sources, by an IPCC recommended FOD(firstorder decay) model. The location, capacity and age of landfills constitute the three dimensions of the emission factors matrix, which were obtained by laboratory analysis and in situ investigation. Key parameters such as waste composition,degradable organic carbon ratio, CH4 correction factor, oxidation factor and recovery rate, were carefully analyzed in terms of these three dimensions. The point sources database consists of 2,107 MSW landfills in cities and towns of China in 2007. The results show that the CH4 emissions from MSW landfills were 1.186 Mt in 2007. Compared with the CH4 emissions of 2.20 Mt in 2005, the significant discrepancy mainly comes from statistical data of landfills, e.g., number of landfills and amount of waste disposed in landfills. CH4 emissions were lower than 700 t for most of the landfills, whereas there were 279 landfills with emissions larger than 1,000 t, and only 10 landfills with emissions larger than 10,000 t.Jiangsu province ranks the largest emitter with 98,700 t while Tibet is the smallest emitter with 2,100 t. In general,the emissions from eastern provinces, such as Jiangsu, Guangdong and Zhejiang, were larger than those from western provinces, such as Ningxia, Tibet and Qinghai.展开更多
The existence and its movement rule of crystalline structure defect are closely related to the diffusion, solid phase reaction, sintering, phase transformation as well as the physical and chemical properties of materi...The existence and its movement rule of crystalline structure defect are closely related to the diffusion, solid phase reaction, sintering, phase transformation as well as the physical and chemical properties of materials. Point defect theory has been widely applied in material mineralization research, unfavorable transformation controlling, material modification, the research and development of new materials and so on. Point defect theory is one of the important theories for new material research and development. Herein we mainly discuss the application of point defect theory in some structural material researches.展开更多
A sensitive method based on solid phase PCR on oligonucleotide array was established to detect two point mutations 1896G-A and 1901G-A in hepatitis B virus (HBV) DNA, in which 6 probes including these two point mutati...A sensitive method based on solid phase PCR on oligonucleotide array was established to detect two point mutations 1896G-A and 1901G-A in hepatitis B virus (HBV) DNA, in which 6 probes including these two point mutations were immobilized on modified glass slides through 5' terminal linker, while the 3' terminal was made to be free. The mutated loci were designed to locate on the last nucleotides of 3' terminal respectively, and the positive control probes lacked the last nucleotide of 3' terminal in comparison with the probes used for detection. Probes fixed on oligonucleotide array were also the solid phase amplification primers. One pair of liquid primers was used to amplify the short template product from whole HBV DNA. Using target DNA as template, the solid primers were extended under the action of Taq DNA polymerase and incorporated with Cy-3dCTP as marker. During the thermal cycling reaction, probes served as solid phase amplification primers and amplification products bound to the oligonucleotide array, which could be visualized by incorporation with fluorescent dyes. After amplification, the oligonucleotide array was washed, performed with laser scanning, and then used for quantitative analysis to obtain the information for mutations. The hybridization results were compared with DNA sequencing. It was demonstrated that in case of sample A, the ratios of fluorescence intensities in wide type and in the mutated types of 1896G-A and 1901G-A mutations in HBV were 3.81:1 and 1:3.79 respectively, while, in case of sample B, those were 1:2.89 and 1:3.03 respectively, indicating the presence of point mutations in these two loci. These results correlated to those obtained from DNA sequencing analysis in which the fluorescence intensity ratios in wide type and in the mutated types of 1996G-A and 1901D-A mutations in HBV were 1.26:1 and 1.67:1 respectively. From the above observations, it is evident that the method using solid phase PCR based on oligonucleotide array appears to be a sensitive and promising way to detect mutations with low-density.展开更多
Indisputably, flooding is one of the predicaments that have plagued many countries throughout the world. Consequently, Improvement of Municipal Solid Waste Management-(MSWM) has recently become one of the ways that is...Indisputably, flooding is one of the predicaments that have plagued many countries throughout the world. Consequently, Improvement of Municipal Solid Waste Management-(MSWM) has recently become one of the ways that is believed to help in reducing the impact of flooding. Following the fact that Dar es Salaam, the commercial capital, has nearly 5 million inhabitants and several of the wards are in flood-prone areas, the City authorities introduced new models of MSWM by incorporating public-private partnership as a deliberate action envisioned to improve MSWM. Nevertheless, the extent to which the strategy is effective in minimizing flood risks had not been adequately researched, which prompted a need to conduct a study. Specifically, the study sought to: assess the current practice of SWM in the settlement;examine the extent to which flood risk had been reduced given the application of the new models of SWM. This is primarily a case study which used Keko Machungwa in Dar es Salaam as the study area. Different forms of data collections tools were used for instance interviews of households and officials, photographs, spatial data etc. The findings indicated that Jukwaa la Wanawake in Keko Machungwa, a newly emerged community-driven organization was doing a fairly good job in handling SWM. This social entity was capable of collecting 40 tons of solid wastes per week and arranged for transportation. Overall, there was a marked decrease in haphazard dumping within the settlement. Despite the improvement, however, flooding was still persistent and was an alarming challenge. To that effect, this study recommends that improving solid waste collection could help overcome the problem of flooding particularly if integrated with other initiatives which include 1) Investment in robust flood control structures;2) Adherence to Urban planning and disaster management policies which prohibit development in hazardous areas, an instance of which being demolishing the existing building structures located in the water way in Keko Machungwa and;3) Initiate large scale flood risk reduction settlement schemes.展开更多
基金funded by the Project Study on Key Issues of China City Carbon Emission Inventory (No. 41101500)supported by National Natural Science Foundation of China
文摘The methane(CH4) emissions from municipal solid waste(MSW) landfills in China in 2007 were estimated based on database of the three-dimensional emission factors matrix and point sources, by an IPCC recommended FOD(firstorder decay) model. The location, capacity and age of landfills constitute the three dimensions of the emission factors matrix, which were obtained by laboratory analysis and in situ investigation. Key parameters such as waste composition,degradable organic carbon ratio, CH4 correction factor, oxidation factor and recovery rate, were carefully analyzed in terms of these three dimensions. The point sources database consists of 2,107 MSW landfills in cities and towns of China in 2007. The results show that the CH4 emissions from MSW landfills were 1.186 Mt in 2007. Compared with the CH4 emissions of 2.20 Mt in 2005, the significant discrepancy mainly comes from statistical data of landfills, e.g., number of landfills and amount of waste disposed in landfills. CH4 emissions were lower than 700 t for most of the landfills, whereas there were 279 landfills with emissions larger than 1,000 t, and only 10 landfills with emissions larger than 10,000 t.Jiangsu province ranks the largest emitter with 98,700 t while Tibet is the smallest emitter with 2,100 t. In general,the emissions from eastern provinces, such as Jiangsu, Guangdong and Zhejiang, were larger than those from western provinces, such as Ningxia, Tibet and Qinghai.
基金This work was supported by the "863" program (No. 2003AA322020)
文摘The existence and its movement rule of crystalline structure defect are closely related to the diffusion, solid phase reaction, sintering, phase transformation as well as the physical and chemical properties of materials. Point defect theory has been widely applied in material mineralization research, unfavorable transformation controlling, material modification, the research and development of new materials and so on. Point defect theory is one of the important theories for new material research and development. Herein we mainly discuss the application of point defect theory in some structural material researches.
文摘A sensitive method based on solid phase PCR on oligonucleotide array was established to detect two point mutations 1896G-A and 1901G-A in hepatitis B virus (HBV) DNA, in which 6 probes including these two point mutations were immobilized on modified glass slides through 5' terminal linker, while the 3' terminal was made to be free. The mutated loci were designed to locate on the last nucleotides of 3' terminal respectively, and the positive control probes lacked the last nucleotide of 3' terminal in comparison with the probes used for detection. Probes fixed on oligonucleotide array were also the solid phase amplification primers. One pair of liquid primers was used to amplify the short template product from whole HBV DNA. Using target DNA as template, the solid primers were extended under the action of Taq DNA polymerase and incorporated with Cy-3dCTP as marker. During the thermal cycling reaction, probes served as solid phase amplification primers and amplification products bound to the oligonucleotide array, which could be visualized by incorporation with fluorescent dyes. After amplification, the oligonucleotide array was washed, performed with laser scanning, and then used for quantitative analysis to obtain the information for mutations. The hybridization results were compared with DNA sequencing. It was demonstrated that in case of sample A, the ratios of fluorescence intensities in wide type and in the mutated types of 1896G-A and 1901G-A mutations in HBV were 3.81:1 and 1:3.79 respectively, while, in case of sample B, those were 1:2.89 and 1:3.03 respectively, indicating the presence of point mutations in these two loci. These results correlated to those obtained from DNA sequencing analysis in which the fluorescence intensity ratios in wide type and in the mutated types of 1996G-A and 1901D-A mutations in HBV were 1.26:1 and 1.67:1 respectively. From the above observations, it is evident that the method using solid phase PCR based on oligonucleotide array appears to be a sensitive and promising way to detect mutations with low-density.
文摘Indisputably, flooding is one of the predicaments that have plagued many countries throughout the world. Consequently, Improvement of Municipal Solid Waste Management-(MSWM) has recently become one of the ways that is believed to help in reducing the impact of flooding. Following the fact that Dar es Salaam, the commercial capital, has nearly 5 million inhabitants and several of the wards are in flood-prone areas, the City authorities introduced new models of MSWM by incorporating public-private partnership as a deliberate action envisioned to improve MSWM. Nevertheless, the extent to which the strategy is effective in minimizing flood risks had not been adequately researched, which prompted a need to conduct a study. Specifically, the study sought to: assess the current practice of SWM in the settlement;examine the extent to which flood risk had been reduced given the application of the new models of SWM. This is primarily a case study which used Keko Machungwa in Dar es Salaam as the study area. Different forms of data collections tools were used for instance interviews of households and officials, photographs, spatial data etc. The findings indicated that Jukwaa la Wanawake in Keko Machungwa, a newly emerged community-driven organization was doing a fairly good job in handling SWM. This social entity was capable of collecting 40 tons of solid wastes per week and arranged for transportation. Overall, there was a marked decrease in haphazard dumping within the settlement. Despite the improvement, however, flooding was still persistent and was an alarming challenge. To that effect, this study recommends that improving solid waste collection could help overcome the problem of flooding particularly if integrated with other initiatives which include 1) Investment in robust flood control structures;2) Adherence to Urban planning and disaster management policies which prohibit development in hazardous areas, an instance of which being demolishing the existing building structures located in the water way in Keko Machungwa and;3) Initiate large scale flood risk reduction settlement schemes.
