Material flow and phase transformation were studied at the interface of dissimilar joint between Al 6013 and Mg, produced by stir friction welding （FSW） experiments. Defect-free weld was obtained when aluminum and m...Material flow and phase transformation were studied at the interface of dissimilar joint between Al 6013 and Mg, produced by stir friction welding （FSW） experiments. Defect-free weld was obtained when aluminum and magnesium were placed in the advancing side and retreating side respectively and the tool was placed 1 mm off the weld centerline into the aluminum side. In order to understand the material flow during FSW, steel shots were implanted as indexes into the welding path. After welding, using X-ray images, secondary positions of the steel shots were evaluated. It was revealed that steel shots implanted in advancing side were penetrated from the advancing side into the retreating side, whereas the shots implanted in the retreating side remained in the retreating side, without penetrating into the advancing side. The welded specimens were also heat treated. The effects of heat treatment on the mechanical properties of the welds and the formation of new intermetallic layers were investigated. Two intermetallic compounds, Al3Mg2 and Al12Mg17, were formed sequentially at Al6013/Mg interface.展开更多
Chromium ore fines containing coal (COFCC) can be rapidly heated by microwave to conduct the voluminal reduction, which lays a foundation of getting sponge ferrochromium powders with a lower content of C. Under the co...Chromium ore fines containing coal (COFCC) can be rapidly heated by microwave to conduct the voluminal reduction, which lays a foundation of getting sponge ferrochromium powders with a lower content of C. Under the conditions of COFCC with n(O)-n(C) (molar ratio) as 1.00-0.84 and n(SiO2)-n(CaO) as 1.00-0.39, the samples were heated by 10 kW microwave power to reach the given temperatures and held for different times respectively. The results show that the low-C-Cr ferrochromium metal phase in the reduced materials forms before the high-C-Cr ferrochromium metal phase does. With increasing temperature the C content of ferrochromium metals is in a positive correlation with the content of Cr. The C content of ferrochromium metal in reduced materials is 0-10.07% with an average value of 4.68%. With the increase of holding time the Cr content in ferrochromium metals is in a negative correlation with the content of C, while the content of Fe changes in the contrary way. In the microwave field the kinetic conditions of carburization are closely related with the temperature of microwave heating, holding time and carbon fitting ratio.展开更多
An actin encoding gene was cloned by using RT-PCR, 3’ RACE and 5’ RACE from abalone Haliotis discus hannai. The full length of the gene is 1532 base pairs, which contains a long 3’ untranslated region of 307 base p...An actin encoding gene was cloned by using RT-PCR, 3’ RACE and 5’ RACE from abalone Haliotis discus hannai. The full length of the gene is 1532 base pairs, which contains a long 3’ untranslated region of 307 base pairs and 79 base pairs of 5’ untranslated sequence. The open reading frame encodes 376 amino acid residues. Sequence comparison with those of human and other mollusks showed high conservation among species at amino acid level. The identities was 96%, 97% and 96% respectively compared with Aplysia californica, Biomphalaria glabrata and Homo sapience β-actin. It is also indicated that this actin is more similar to the human cytoplasmic actin (β-actin) than to human muscle actin.展开更多
In order to further improve the driving performance of ionic polymer metal composites(IPMCs),Nafion/graphene quantum dots(GQDs)hybrid membranes incorporating GQDs with various contents of 0,0.1 wt.%,0.5 wt.%,1.0 wt.%,...In order to further improve the driving performance of ionic polymer metal composites(IPMCs),Nafion/graphene quantum dots(GQDs)hybrid membranes incorporating GQDs with various contents of 0,0.1 wt.%,0.5 wt.%,1.0 wt.%,2.0 wt.%and 4.0 wt.%were fabricated by solution casting,and then IPMCs were manufactured by electroless plating.The water contents and elastic moduli of the hybrid membranes were tested.The morphology characteristics of the hybrid membranes and the IPMCs were observed,and the current,AC impedance,blocking force and displacement of the IPMCs were measured.The results show that the elastic modulus of the hybrid membranes decreases,the water content increases,and the actuation performance of the IPMCs improves significantly after the addition of GQDs.IPMC with 1.0 wt.%GQDs exhibits the best driving property.Compared with the IPMC without GQDs,the working current,ion conductivity,blocking force,and tip displacement increase by 94.67%,311.11%,53.66%,and 66.07%,respectively.These results lay a solid foundation for the preparation of IPMCs with high performance,and further broaden their applications in biomedical devices and bionic robots.展开更多
Microbiological investigation of the fossil animals preserved in permafrost represents obvious interest for science. Lack of data in this sphere gives even greater importance to any findings giving us opportunity to l...Microbiological investigation of the fossil animals preserved in permafrost represents obvious interest for science. Lack of data in this sphere gives even greater importance to any findings giving us opportunity to learn more about remote past of microorganisms. In this respect, preserved remains of fossil are considered as unique biological materials for scientific investigations. Bacillus bacteria strains isolated from the paleomicrobiota of mammoth fauna are not only have high durability （20-30 thousand of years） in permafrost, but are still able to produce biologically active substances. Strains of bacteria of the genus Bacillus, isolated from the tissues of the representatives of the mammoth fauna have strong antagonistic properties to hemolytic streptococci--Streptococcus equi, pathogenic for animals--Salmonella abortus equi, also toxigenic micromycetes genera Aspergillus, Alternuria, Penicillum and fungal pathogens of plant diseases--Botrytis cimeria and Fuzarium oxysporium. The strains of bacteria of the genus Bacillus are not pathogenic to plants and animals, but initially resistant to wide range of antibiotics. Dominance strains of Bacillus bacteria, producing strong bacteriocins in the soft tissues of fossil animals, contributing to their long cryo bio conservation. In addition, bacterial strains of Bacillus subtilis, isolated from paleo microbiota have strong oxidizing properties. Microbiota of fossils preserved in permafrost of Yakutia is of particular interest for microbiology and modem biotechnology.展开更多
In the research of bio-molecular chips and sensors, extra electric biases are most often employed to control and manipulate the DNA and protein molecules moving through micro/nano-fluidic channels. In order to accurat...In the research of bio-molecular chips and sensors, extra electric biases are most often employed to control and manipulate the DNA and protein molecules moving through micro/nano-fluidic channels. In order to accurately and flexibly control the bio-molecules as they move within the channels, a clear understanding of how the current changes within the buffer solution caused by an applied bias is fundamental. In this report, the current changed value of different buffer solutions, e.g., KC1, TE, and TBE was systematically studied with real-time monitoring and quantitative analysis in the situation of the buffers moving through a fluidic channel with a 5 μm inner diameter, driven by biases of 50 or 100 mV. The results revealed that the relation- ship between the current changed value and the pause interval of the applied electric field is highly consistent with the Hill Equation, which is helpful for accurately detecting and manipulating single biomolecules in microfluidic sensors and biochips.展开更多
文摘Material flow and phase transformation were studied at the interface of dissimilar joint between Al 6013 and Mg, produced by stir friction welding （FSW） experiments. Defect-free weld was obtained when aluminum and magnesium were placed in the advancing side and retreating side respectively and the tool was placed 1 mm off the weld centerline into the aluminum side. In order to understand the material flow during FSW, steel shots were implanted as indexes into the welding path. After welding, using X-ray images, secondary positions of the steel shots were evaluated. It was revealed that steel shots implanted in advancing side were penetrated from the advancing side into the retreating side, whereas the shots implanted in the retreating side remained in the retreating side, without penetrating into the advancing side. The welded specimens were also heat treated. The effects of heat treatment on the mechanical properties of the welds and the formation of new intermetallic layers were investigated. Two intermetallic compounds, Al3Mg2 and Al12Mg17, were formed sequentially at Al6013/Mg interface.
基金Project(50474083) supported by the National Natural Science Foundation of ChinaProject supported by the Baoshan Iron & Steel Co. Ltd. of China
文摘Chromium ore fines containing coal (COFCC) can be rapidly heated by microwave to conduct the voluminal reduction, which lays a foundation of getting sponge ferrochromium powders with a lower content of C. Under the conditions of COFCC with n(O)-n(C) (molar ratio) as 1.00-0.84 and n(SiO2)-n(CaO) as 1.00-0.39, the samples were heated by 10 kW microwave power to reach the given temperatures and held for different times respectively. The results show that the low-C-Cr ferrochromium metal phase in the reduced materials forms before the high-C-Cr ferrochromium metal phase does. With increasing temperature the C content of ferrochromium metals is in a positive correlation with the content of Cr. The C content of ferrochromium metal in reduced materials is 0-10.07% with an average value of 4.68%. With the increase of holding time the Cr content in ferrochromium metals is in a negative correlation with the content of C, while the content of Fe changes in the contrary way. In the microwave field the kinetic conditions of carburization are closely related with the temperature of microwave heating, holding time and carbon fitting ratio.
基金supported by the Special Funds for the Major State Basic Research Projects(G1999012012)the Key Laboratory of Mariculture of Ministry of Education,Ocean University of China
文摘An actin encoding gene was cloned by using RT-PCR, 3’ RACE and 5’ RACE from abalone Haliotis discus hannai. The full length of the gene is 1532 base pairs, which contains a long 3’ untranslated region of 307 base pairs and 79 base pairs of 5’ untranslated sequence. The open reading frame encodes 376 amino acid residues. Sequence comparison with those of human and other mollusks showed high conservation among species at amino acid level. The identities was 96%, 97% and 96% respectively compared with Aplysia californica, Biomphalaria glabrata and Homo sapience β-actin. It is also indicated that this actin is more similar to the human cytoplasmic actin (β-actin) than to human muscle actin.
基金Projects(51605220,U1637101)supported by the National Natural Science Foundation of ChinaProject(BK20160793)supported by the Jiangsu Provincial Natural Science Foundation,ChinaProject(NS2020029)supported by the Fundamental Research Funds for the Central Universities,China。
文摘In order to further improve the driving performance of ionic polymer metal composites(IPMCs),Nafion/graphene quantum dots(GQDs)hybrid membranes incorporating GQDs with various contents of 0,0.1 wt.%,0.5 wt.%,1.0 wt.%,2.0 wt.%and 4.0 wt.%were fabricated by solution casting,and then IPMCs were manufactured by electroless plating.The water contents and elastic moduli of the hybrid membranes were tested.The morphology characteristics of the hybrid membranes and the IPMCs were observed,and the current,AC impedance,blocking force and displacement of the IPMCs were measured.The results show that the elastic modulus of the hybrid membranes decreases,the water content increases,and the actuation performance of the IPMCs improves significantly after the addition of GQDs.IPMC with 1.0 wt.%GQDs exhibits the best driving property.Compared with the IPMC without GQDs,the working current,ion conductivity,blocking force,and tip displacement increase by 94.67%,311.11%,53.66%,and 66.07%,respectively.These results lay a solid foundation for the preparation of IPMCs with high performance,and further broaden their applications in biomedical devices and bionic robots.
文摘Microbiological investigation of the fossil animals preserved in permafrost represents obvious interest for science. Lack of data in this sphere gives even greater importance to any findings giving us opportunity to learn more about remote past of microorganisms. In this respect, preserved remains of fossil are considered as unique biological materials for scientific investigations. Bacillus bacteria strains isolated from the paleomicrobiota of mammoth fauna are not only have high durability （20-30 thousand of years） in permafrost, but are still able to produce biologically active substances. Strains of bacteria of the genus Bacillus, isolated from the tissues of the representatives of the mammoth fauna have strong antagonistic properties to hemolytic streptococci--Streptococcus equi, pathogenic for animals--Salmonella abortus equi, also toxigenic micromycetes genera Aspergillus, Alternuria, Penicillum and fungal pathogens of plant diseases--Botrytis cimeria and Fuzarium oxysporium. The strains of bacteria of the genus Bacillus are not pathogenic to plants and animals, but initially resistant to wide range of antibiotics. Dominance strains of Bacillus bacteria, producing strong bacteriocins in the soft tissues of fossil animals, contributing to their long cryo bio conservation. In addition, bacterial strains of Bacillus subtilis, isolated from paleo microbiota have strong oxidizing properties. Microbiota of fossils preserved in permafrost of Yakutia is of particular interest for microbiology and modem biotechnology.
基金supported by the Major Research Plan of the National Natural Science Foundation of China(Grant No.91123030)the Interna-tional Cooperation Foundation of the National Science and Technology Major Project of the Ministry of Science and Technology of China(Grant No.2011DFA12220)the National Natural Science Foundation of China(Grant No.61378083)
文摘In the research of bio-molecular chips and sensors, extra electric biases are most often employed to control and manipulate the DNA and protein molecules moving through micro/nano-fluidic channels. In order to accurately and flexibly control the bio-molecules as they move within the channels, a clear understanding of how the current changes within the buffer solution caused by an applied bias is fundamental. In this report, the current changed value of different buffer solutions, e.g., KC1, TE, and TBE was systematically studied with real-time monitoring and quantitative analysis in the situation of the buffers moving through a fluidic channel with a 5 μm inner diameter, driven by biases of 50 or 100 mV. The results revealed that the relation- ship between the current changed value and the pause interval of the applied electric field is highly consistent with the Hill Equation, which is helpful for accurately detecting and manipulating single biomolecules in microfluidic sensors and biochips.
