The damage was noted during the usage of the pipe system which was made out of austenite steel 316L on the assembly line for the production of urea. In order to find out the cause of such damage, the samples of pipes ...The damage was noted during the usage of the pipe system which was made out of austenite steel 316L on the assembly line for the production of urea. In order to find out the cause of such damage, the samples of pipes were taken at the places where the most damage took place. Samples were taken in the form of film, sediment and/or sludge from inner and the outer surface of the pipes. As well as each pieces of pipes were further cut into 10 mm x 10 mm plates. The prepared samples were studied using X-ray diffraction, X-ray emission spectrometry, scanning electron microscope and microanalysis as well as a light microscope. The results implicate microstructural changes within the inner wall of the pipe which was caused by intercrystalline corrosion. Such corrosion in the investigated samples of sediment and/or sludge appeared due to the damage of the protective film during the aggressive phases,展开更多
Starch is one of the most promising natural polymers source However, the properties of starch-based materials are not satisfactory. because it is an adsorbent, universally available and low cost. This weakness can be ...Starch is one of the most promising natural polymers source However, the properties of starch-based materials are not satisfactory. because it is an adsorbent, universally available and low cost. This weakness can be overcome by adding other materials to form biocomposite. Biocomposite is a composite material of a natural polymer （organic phase） and reinforcement/filler （inorganic phase）. The use of filler material that has the properties of semiconductor will produce composite that have semiconducting properties as well. In this research, biocomposite was cast using ZnO as filler in the matrix of sweet potato starch plasticised by glycerol. From the results of XRD （X-ray diffraction） and SEM （scanning electron microscope） analysis showed that ZnO has been dispersed in the matrix and the results of FT-IR was found that sweet potato starch, glycerol, and ZnO are united to form biocomposite. From the test results of mechanical, physical and electrical properties were found that the addition of ZnO concentration of 1%, 3% and 6% lead to improvement of tensile strength from 24.68 kgf/cm2 to 34.43 kgffcm2, decrease in elongation from 26.96% to 8.5%, decrease in water vapour transmission rate from 8.6270 gr·m^2·h^-1 to 4.581 gr·m^2·h^-1, increase in UV absorbance, and conductivity of 5.864 × 10^-7 S/cm. Addition of glycerol concentration of 15%, 25% and 35% wt causes an increase in elongation from 8.75% to 33.04%, and decrease in tensile strength from 54.57% to 14.64%.展开更多
The staphylococcal nuclease, encoded by the nucl gene, is an important virulence factor of Staphylococcus aureus. However, the physiological role of the nuclease has not been fully characterized. The current study obs...The staphylococcal nuclease, encoded by the nucl gene, is an important virulence factor of Staphylococcus aureus. However, the physiological role of the nuclease has not been fully characterized. The current study observed that biofilm development could be prevented in staphylococcal nuclease-producing strains of S. aureus; however, when the nucl gene was knocked out, the ability to form a biofilm significantly increased. Scanning electron and confocal scanning laser microscopy were used to evaluate the role of the nucl gene in biofilm formation. Moreover, the nucl gene product, staphylococcal nuclease, and re- combinant NUC1 protein were found to have a visible effect on other biofilm-forming bacteria, such as Pseudomonas aeru- ginosa, Actinobacillus pleuropneurnoniae, and Haernophilus parasuis. The current study showed a direct relationship between staphylococcal nuclease production and the prevention of biofilm development. The findings from this study underscore the important role of staphylococcal nuclease activity to prevent biofilm formation in S. aureus. They also provided evidence for the biological role of staphylococcal nucleases in other organisms.展开更多
Porous silicon （PSi） prepared from Pt metal-assisted chemical etching （MACE） was demonstrated to possess higher hydrosi- lylation efficiency （-57%） than anodized PSi （-11%） by surface reaction with co-undeceny...Porous silicon （PSi） prepared from Pt metal-assisted chemical etching （MACE） was demonstrated to possess higher hydrosi- lylation efficiency （-57%） than anodized PSi （-11%） by surface reaction with co-undecenyl alcohol （UO）. Deconvolution of the SiHx （x = 1-3） stretching bands revealed the abundance of SiH2 species on MaCE PSi was 53%, -10% higher than on ano- dized samples, while both of Sill1 and Sill3 were -5% lower correspondently on MaCE PSi than on anodized samples. The surface SiHx abundances were suggested to account for the higher hydrosilylation efficiency on MaCE PSi. Optimization of Pt-assisted chemical etching parameters suggested a 7-15 nm thick Pt-coating and an etching time of 3-10 min for biochip ap- plications. Scanning electron microscopy images revealed that an isotropic top meso-porous layer was beneficial for hydrosi- lylation and long-term durability under ambient conditions. To end, an example of histidine-tagged protein immobilization and microarray was illustrated. Combining the materials＇ property, surface chemistry, and micro-fabrication technology together, we envision that silicon based biochip applications have a prosperous future.展开更多
Electron-positron pair production in an arbitrary polarized ultrastrong laser field is investigated in the first order perturbation approximation in which the Volkov states are used for convenient calculation of scatt...Electron-positron pair production in an arbitrary polarized ultrastrong laser field is investigated in the first order perturbation approximation in which the Volkov states are used for convenient calculation of scattering amplitude and cross section. It is found surprisingly that the optimal pair production depends strongly on the polarization. For some cases of field parameters, the optimal field is e11iptically polarized or evenly circularly polarized one, rather than the usual linear polarization as indicated by previous works interesting unexpected features are a/so discussed briefly. Some insights into pair generation are given and some展开更多
We present temperature and power dependent photoluminescence measurements on CdSe nanowires synthesized via vapor-phase with and without the use of a metal catalyst. Nanowires produced without a catalyst can be optimi...We present temperature and power dependent photoluminescence measurements on CdSe nanowires synthesized via vapor-phase with and without the use of a metal catalyst. Nanowires produced without a catalyst can be optimized to yield higher quantum efficiency, and narrower and spatially uniform emission, when compared to the catalyst-assisted ones. Emission at energies lower than the band-edge is also found in both cases. By combining spatially-resolved photoluminescence and electron microscopy on the same nanowires, we show that catalyst-free nanowires exhibit a low-energy peak with sharp phonon replica, whereas for catalyst-assisted nanowires low-energy emission is linked to the presence of nanostructures with extended morphological defects.展开更多
We report on electrical and optical properties of p＋-i-n＋ photodetectors/solar cells based on square millimeter arrays of InP nanowires （NWs） grown on InP substrates. The study includes a sample series where the p...We report on electrical and optical properties of p＋-i-n＋ photodetectors/solar cells based on square millimeter arrays of InP nanowires （NWs） grown on InP substrates. The study includes a sample series where the p＋-segment length was varied between 0 and 250 nm, as well as solar cells with 9.3% efficiency with similar design. The electrical data for all devices display clear rectifying behavior with an ideality factor between 1.8 and 2.5 at 300 K. From spectrally resolved photocurrent measurements, we conclude that the photocurrent generation process depends strongly on the p^-segment length. Without a p＋-segment, photogenerated carriers funneled from the substrate into the NWs contribute strongly to the photocurrent. Adding a p＋-segment decouples the substrate and shifts the depletion region, and collection of photogenerated carriers, to the NWs, in agreement with theoretical modeling. In optimized solar cells, clear spectral signatures of interband transitions in the zinc blende and wurtzite InP layers of the mixed-phase i-segments are observed. Complementary electroluminescence, transmission electron microscopy （TEM）, as well as measurements of the dependence of the photocurrent on angle of incidence and polarization, support our interpretations.展开更多
A zinc-blende （sphalerite） crystallographic structure of SnSi nanocrystals generated by molecular-beam epitaxy is observed by electron microscopy techniques in a Si matrix. Ab initio density-functional modeling reve...A zinc-blende （sphalerite） crystallographic structure of SnSi nanocrystals generated by molecular-beam epitaxy is observed by electron microscopy techniques in a Si matrix. Ab initio density-functional modeling reveals a stabilizing effect of the Si matrix, which results in the lowest formation enthalpy of SnSi nanocrystals having the unexpected zinc-blende structure. Such nanocrystals could be applied in Si photonics to function as non-centrosymmetric media for the nonlinear optical process of second harmonic generation.展开更多
文摘The damage was noted during the usage of the pipe system which was made out of austenite steel 316L on the assembly line for the production of urea. In order to find out the cause of such damage, the samples of pipes were taken at the places where the most damage took place. Samples were taken in the form of film, sediment and/or sludge from inner and the outer surface of the pipes. As well as each pieces of pipes were further cut into 10 mm x 10 mm plates. The prepared samples were studied using X-ray diffraction, X-ray emission spectrometry, scanning electron microscope and microanalysis as well as a light microscope. The results implicate microstructural changes within the inner wall of the pipe which was caused by intercrystalline corrosion. Such corrosion in the investigated samples of sediment and/or sludge appeared due to the damage of the protective film during the aggressive phases,
文摘Starch is one of the most promising natural polymers source However, the properties of starch-based materials are not satisfactory. because it is an adsorbent, universally available and low cost. This weakness can be overcome by adding other materials to form biocomposite. Biocomposite is a composite material of a natural polymer （organic phase） and reinforcement/filler （inorganic phase）. The use of filler material that has the properties of semiconductor will produce composite that have semiconducting properties as well. In this research, biocomposite was cast using ZnO as filler in the matrix of sweet potato starch plasticised by glycerol. From the results of XRD （X-ray diffraction） and SEM （scanning electron microscope） analysis showed that ZnO has been dispersed in the matrix and the results of FT-IR was found that sweet potato starch, glycerol, and ZnO are united to form biocomposite. From the test results of mechanical, physical and electrical properties were found that the addition of ZnO concentration of 1%, 3% and 6% lead to improvement of tensile strength from 24.68 kgf/cm2 to 34.43 kgffcm2, decrease in elongation from 26.96% to 8.5%, decrease in water vapour transmission rate from 8.6270 gr·m^2·h^-1 to 4.581 gr·m^2·h^-1, increase in UV absorbance, and conductivity of 5.864 × 10^-7 S/cm. Addition of glycerol concentration of 15%, 25% and 35% wt causes an increase in elongation from 8.75% to 33.04%, and decrease in tensile strength from 54.57% to 14.64%.
基金supported by the National Natural Science Foundation of China (Grant Nos. 31071515 and 31070113)the Special Foundation for Young Scientists of Sichuan Province,China (Grant No. 2011JQ0043)the Fundamental Research Funds for the Central Universities,Southwest University for Nationalities (Grant No. 09NZYZJ04)
文摘The staphylococcal nuclease, encoded by the nucl gene, is an important virulence factor of Staphylococcus aureus. However, the physiological role of the nuclease has not been fully characterized. The current study observed that biofilm development could be prevented in staphylococcal nuclease-producing strains of S. aureus; however, when the nucl gene was knocked out, the ability to form a biofilm significantly increased. Scanning electron and confocal scanning laser microscopy were used to evaluate the role of the nucl gene in biofilm formation. Moreover, the nucl gene product, staphylococcal nuclease, and re- combinant NUC1 protein were found to have a visible effect on other biofilm-forming bacteria, such as Pseudomonas aeru- ginosa, Actinobacillus pleuropneurnoniae, and Haernophilus parasuis. The current study showed a direct relationship between staphylococcal nuclease production and the prevention of biofilm development. The findings from this study underscore the important role of staphylococcal nuclease activity to prevent biofilm formation in S. aureus. They also provided evidence for the biological role of staphylococcal nucleases in other organisms.
基金the financial support of the National Basic Research Program of China(2013CB922101)the National Natural Science Foundation of China(20827001,91027019,21021062)
文摘Porous silicon （PSi） prepared from Pt metal-assisted chemical etching （MACE） was demonstrated to possess higher hydrosi- lylation efficiency （-57%） than anodized PSi （-11%） by surface reaction with co-undecenyl alcohol （UO）. Deconvolution of the SiHx （x = 1-3） stretching bands revealed the abundance of SiH2 species on MaCE PSi was 53%, -10% higher than on ano- dized samples, while both of Sill1 and Sill3 were -5% lower correspondently on MaCE PSi than on anodized samples. The surface SiHx abundances were suggested to account for the higher hydrosilylation efficiency on MaCE PSi. Optimization of Pt-assisted chemical etching parameters suggested a 7-15 nm thick Pt-coating and an etching time of 3-10 min for biochip ap- plications. Scanning electron microscopy images revealed that an isotropic top meso-porous layer was beneficial for hydrosi- lylation and long-term durability under ambient conditions. To end, an example of histidine-tagged protein immobilization and microarray was illustrated. Combining the materials＇ property, surface chemistry, and micro-fabrication technology together, we envision that silicon based biochip applications have a prosperous future.
基金Supported by the National Natural Science Foundation of China (NNSFC) under Grant Nos. 11175023, 11175020the Fundamental Research Funds for the Central Universities (FRFCU)
文摘Electron-positron pair production in an arbitrary polarized ultrastrong laser field is investigated in the first order perturbation approximation in which the Volkov states are used for convenient calculation of scattering amplitude and cross section. It is found surprisingly that the optimal pair production depends strongly on the polarization. For some cases of field parameters, the optimal field is e11iptically polarized or evenly circularly polarized one, rather than the usual linear polarization as indicated by previous works interesting unexpected features are a/so discussed briefly. Some insights into pair generation are given and some
文摘We present temperature and power dependent photoluminescence measurements on CdSe nanowires synthesized via vapor-phase with and without the use of a metal catalyst. Nanowires produced without a catalyst can be optimized to yield higher quantum efficiency, and narrower and spatially uniform emission, when compared to the catalyst-assisted ones. Emission at energies lower than the band-edge is also found in both cases. By combining spatially-resolved photoluminescence and electron microscopy on the same nanowires, we show that catalyst-free nanowires exhibit a low-energy peak with sharp phonon replica, whereas for catalyst-assisted nanowires low-energy emission is linked to the presence of nanostructures with extended morphological defects.
文摘We report on electrical and optical properties of p＋-i-n＋ photodetectors/solar cells based on square millimeter arrays of InP nanowires （NWs） grown on InP substrates. The study includes a sample series where the p＋-segment length was varied between 0 and 250 nm, as well as solar cells with 9.3% efficiency with similar design. The electrical data for all devices display clear rectifying behavior with an ideality factor between 1.8 and 2.5 at 300 K. From spectrally resolved photocurrent measurements, we conclude that the photocurrent generation process depends strongly on the p^-segment length. Without a p＋-segment, photogenerated carriers funneled from the substrate into the NWs contribute strongly to the photocurrent. Adding a p＋-segment decouples the substrate and shifts the depletion region, and collection of photogenerated carriers, to the NWs, in agreement with theoretical modeling. In optimized solar cells, clear spectral signatures of interband transitions in the zinc blende and wurtzite InP layers of the mixed-phase i-segments are observed. Complementary electroluminescence, transmission electron microscopy （TEM）, as well as measurements of the dependence of the photocurrent on angle of incidence and polarization, support our interpretations.
文摘A zinc-blende （sphalerite） crystallographic structure of SnSi nanocrystals generated by molecular-beam epitaxy is observed by electron microscopy techniques in a Si matrix. Ab initio density-functional modeling reveals a stabilizing effect of the Si matrix, which results in the lowest formation enthalpy of SnSi nanocrystals having the unexpected zinc-blende structure. Such nanocrystals could be applied in Si photonics to function as non-centrosymmetric media for the nonlinear optical process of second harmonic generation.
