The potential of using a hypoeutectic, instead of eutectic, Sn-Zn alloy as a lead-free solder has been discussed. The nonequilibrium melting behaviors of a series of Sn-Zn alloys were examined by differential thermal ...The potential of using a hypoeutectic, instead of eutectic, Sn-Zn alloy as a lead-free solder has been discussed. The nonequilibrium melting behaviors of a series of Sn-Zn alloys were examined by differential thermal analysis. It was found that at a heating rate of 5℃/min, Sn-6.SZn exhibited no melting range. Dipping and spreading tests were carried out to characterize the wettability of Sn-Zn alloys on Cu. Both tests exhibited that Sn-6.5Zn has significantly better wettability on Cu than Sn-9Zn. The reaction layers formed during the spreading tests were examined. When the Zn concentration fell between 2.5wt%-9wt%, two reaction layers were formed at the interface, a thick and flat Cu5Zn8 adjacent to Cu and a thin and irregular Cu-Zn-Sn layer adjacent to the alloy. Only a Cu0Sn5 layer was formed when the Zn concentration decreased to 0.5wt%. The total thickness of the reaction layer（s） between the alloy and Cu was found to increase linearly with the Zn concentration.展开更多
To study the efficiency ofDNA gyrase subunit B （gyrB） gene as means of diversity analysis, diversities of gyrB genes in three AMD samples collected from Dabaoshan Mine were studied by analyzing gyrB gene library. Ma...To study the efficiency ofDNA gyrase subunit B （gyrB） gene as means of diversity analysis, diversities of gyrB genes in three AMD samples collected from Dabaoshan Mine were studied by analyzing gyrB gene library. Many novel gyrB sequences and groups were detected. The results show that Acidithiobacillusferrooxidans-like bacteria represented 88.0% of the bacterial population in a sample. However, other two samples showed much high diversities. These diversities were characterized by the reciprocal of Simpson＇s index （l/D）, and show ferrous ion strongly influenced the composition of the microbial communities. The study indicate that gyrB Gene as a phylogenetic discriminator is a good tool to study different strains in same species that were difficult to be distinguished by 16S genes. But now gyrB Gene cannot define clearly unknown sequences to certain lineage, due to the incompleteness of the gyrB database.展开更多
To reveal the effects of Fe2＋ on bacterial communities in the early stages of minerals dissolution, two different acid mine drainage （AMD） samples were collected at Dabaoshan Mine and Shenbu Mine. Community success...To reveal the effects of Fe2＋ on bacterial communities in the early stages of minerals dissolution, two different acid mine drainage （AMD） samples were collected at Dabaoshan Mine and Shenbu Mine. Community successions of AMD niches were analyzed by Amplified Ribosomal DNA Restriction Analysis （ARDRA）, sequencing, and phylogenetic analysis in original AMD samples and their subculture under Fe2＋ concentrations. Although geochemical properties and community structures were greatly different between the two original AMD samples, bacterial community successions were still very similar under high Fe2＋ concentrations. The results showed that Acidithiobacillus ferrooxidans have competitive relationship with other bacterial species living in the AMD, including species that were also capable of oxidizing ferrous ion. A competitive relationship among different At. ferrooxidans strains likewise existed. Some of At. ferrooxidans can grow first under conditions of high ferrous ion concentration, and other At. ferrooxidans species decreased gradually and disappeared. This suggested that these species of At. ferrooxidans are most acidophilic bacteria and afford Fe3＋ to leach other metallic ion in the early stages of minerals dissolution.展开更多
Recently, the frequent extreme natural disasters made enormous damage to the electric grid leading to blackouts. The lifeline system aiming at providing continuous power supply for the important load in extreme natura...Recently, the frequent extreme natural disasters made enormous damage to the electric grid leading to blackouts. The lifeline system aiming at providing continuous power supply for the important load in extreme natural disasters was designed in that condition. In this paper, a developed model for planning of the transformer substation in lifeline system? which considered the effect of existing transformer substations, the motivated areas and punishment areas was proposed. The Hopfield NN was adopted to solve the feeders and the PSO was adopted to new the locations of the transformer substations based on the feeders. The planning result not only took fully use of the existing substation but also get the suitable location for new construction which was satisfactory.展开更多
文摘The potential of using a hypoeutectic, instead of eutectic, Sn-Zn alloy as a lead-free solder has been discussed. The nonequilibrium melting behaviors of a series of Sn-Zn alloys were examined by differential thermal analysis. It was found that at a heating rate of 5℃/min, Sn-6.SZn exhibited no melting range. Dipping and spreading tests were carried out to characterize the wettability of Sn-Zn alloys on Cu. Both tests exhibited that Sn-6.5Zn has significantly better wettability on Cu than Sn-9Zn. The reaction layers formed during the spreading tests were examined. When the Zn concentration fell between 2.5wt%-9wt%, two reaction layers were formed at the interface, a thick and flat Cu5Zn8 adjacent to Cu and a thin and irregular Cu-Zn-Sn layer adjacent to the alloy. Only a Cu0Sn5 layer was formed when the Zn concentration decreased to 0.5wt%. The total thickness of the reaction layer（s） between the alloy and Cu was found to increase linearly with the Zn concentration.
文摘To study the efficiency ofDNA gyrase subunit B （gyrB） gene as means of diversity analysis, diversities of gyrB genes in three AMD samples collected from Dabaoshan Mine were studied by analyzing gyrB gene library. Many novel gyrB sequences and groups were detected. The results show that Acidithiobacillusferrooxidans-like bacteria represented 88.0% of the bacterial population in a sample. However, other two samples showed much high diversities. These diversities were characterized by the reciprocal of Simpson＇s index （l/D）, and show ferrous ion strongly influenced the composition of the microbial communities. The study indicate that gyrB Gene as a phylogenetic discriminator is a good tool to study different strains in same species that were difficult to be distinguished by 16S genes. But now gyrB Gene cannot define clearly unknown sequences to certain lineage, due to the incompleteness of the gyrB database.
文摘To reveal the effects of Fe2＋ on bacterial communities in the early stages of minerals dissolution, two different acid mine drainage （AMD） samples were collected at Dabaoshan Mine and Shenbu Mine. Community successions of AMD niches were analyzed by Amplified Ribosomal DNA Restriction Analysis （ARDRA）, sequencing, and phylogenetic analysis in original AMD samples and their subculture under Fe2＋ concentrations. Although geochemical properties and community structures were greatly different between the two original AMD samples, bacterial community successions were still very similar under high Fe2＋ concentrations. The results showed that Acidithiobacillus ferrooxidans have competitive relationship with other bacterial species living in the AMD, including species that were also capable of oxidizing ferrous ion. A competitive relationship among different At. ferrooxidans strains likewise existed. Some of At. ferrooxidans can grow first under conditions of high ferrous ion concentration, and other At. ferrooxidans species decreased gradually and disappeared. This suggested that these species of At. ferrooxidans are most acidophilic bacteria and afford Fe3＋ to leach other metallic ion in the early stages of minerals dissolution.
文摘Recently, the frequent extreme natural disasters made enormous damage to the electric grid leading to blackouts. The lifeline system aiming at providing continuous power supply for the important load in extreme natural disasters was designed in that condition. In this paper, a developed model for planning of the transformer substation in lifeline system? which considered the effect of existing transformer substations, the motivated areas and punishment areas was proposed. The Hopfield NN was adopted to solve the feeders and the PSO was adopted to new the locations of the transformer substations based on the feeders. The planning result not only took fully use of the existing substation but also get the suitable location for new construction which was satisfactory.
