Creep and anelastic backflow behaviors of pure copper （4N Cu） with grain size dg=40 μm were investigated at low temperatures of T〈0.3Tm （Tm is melting point） and ultra-low creep rates of ε≤1×10^-10 s^-1 b...Creep and anelastic backflow behaviors of pure copper （4N Cu） with grain size dg=40 μm were investigated at low temperatures of T〈0.3Tm （Tm is melting point） and ultra-low creep rates of ε≤1×10^-10 s^-1 by a high strain-resolution measurement （the helicoid spring specimen technique）. Analysis of creep data was based on the scaling factors of creep curves instead of the conventional extrapolated steady-state creep rate. Power-law creep equation is suggested to be the best for describing the primary transient creep behavior, because the pre-parameter does not apparently change with elapsed time. The observed anelastic strains are 1/6 of the calculated elastic strains, and linear viscous behavior was identified from the logarithm plot of the anelastic strain rate versus anelastic strain （slope equals 1）. Therefore, the creep anelasticity is suggested to be due to the unbowing of there-dimensional network of dislocations.展开更多
This review discussed the relationship among copper,human,and bacteria.Copper plays an important role in human immunity.Copper can boost human immune defense reactions at recommended intake level.The content mainly fo...This review discussed the relationship among copper,human,and bacteria.Copper plays an important role in human immunity.Copper can boost human immune defense reactions at recommended intake level.The content mainly focused on copper antibacterial activity and copper antibacterial mechanisms.Conclusions stated that copper antibacterial activity is affected by copper homeostasis mechanisms in bacteria,adhesion,humidity,strain specificity,and manufacturing methods of antibacterial agents.For the preparation of particle antibacterial agents and surface antibacterial agents,this review discussed several manufacturing methods,such as sol−gel,cold spray,and biosynthesis belonging to chemical synthesis,physical synthesis,and biological synthesis,respectively.Sol−gel method contributes to the preparation of particle agents and surface agents.Cold spray technique is utilized in synthesis of surface copper agent.Biosynthesis is a novel technology which can be applied in nanoparticle agent preparation.展开更多
A1N is used as high power LED package material because of its excellent thermal conductivity. But its poor adhesive with metal is not compatible with the later processing sequence. The properties of the bonding betwee...A1N is used as high power LED package material because of its excellent thermal conductivity. But its poor adhesive with metal is not compatible with the later processing sequence. The properties of the bonding between the deposited palladium, silver, copper and the clean Al-terminated （0001） surface of wurtzite AIN are investigated by using the density-functional the- ory. The results show that the sites of deposited metal atoms on N site are more stable than that on A1 site. Relaxations are found at all the studied interfaces. The bonding energies of Pd/A1N, Ag/A1N and Cu/A1N are respectively 2.75, 1.98, 2.26 eV. Hybridizations of s orbit and p orbit of the deposited metal atoms are observed, which contributes to the bonding energy of interface. The moving to lower energy state of the d orbit and the easier transfer of electrons to semi-empty d orbit in the case of deposited Pd results in the higher bonding energy of Pd/A1N interface.展开更多
The aim of this research was to develop effective alternative therapies to reduce antibiotic use in animal agriculture. In this study, the efficacy of copper-modified palygorskite（CM-Pal） in preventing diarrhea caus...The aim of this research was to develop effective alternative therapies to reduce antibiotic use in animal agriculture. In this study, the efficacy of copper-modified palygorskite（CM-Pal） in preventing diarrhea caused by Salmonella was specifically examined both in vitro and in vivo. The CM-Pal was prepared with palygorskite（Pal） and copper nitrate. The antibacterial activity of the CM-Pal was detected by comparing the differences in cell numbers on plate count agar before and after adding the CM-Pal to Salmonella typhimurium cultures. Seventy ICR mice were then allocated into seven groups. Five groups（the treatment groups） were infected with S. typhimurium by intraperitoneal（i.p.） injection and were given Pal, CM-Pal, montmorillonite powder, gentamicin, and physiological saline, respectively. One group（the prevention group） was given CM-Pal before infection with S. typhimurium. Another group（the uninfected group） was not infected with S. typhimurium. The effects of Pal, CM-Pal, montmorillonite powder, and gentamicin on the treatment or prevention of diarrhea in the mice were examined by stool studies, fecal scoring, and assessment of growth performance and villus height. The CM-Pal had satisfactory anti-bacterial properties in vitro： the antibacterial rate was 100% after 2 h incubation with S. typhimurium NJS1 cultures（1×10-6 colony-forming units（CFU）/ml）. In the in vivo experiment, the CM-Pal exerted superior effects in the treatment and prevention of diarrhea in mice compared with Pal, montmorillonite powder, and gentamicin. In the CM-Pal group, no mice showed signs of diarrhea at 24 h post infection（p.i.）, and all mice fully recovered from infection. However, the Pal group, montmorillonite group, and gentamicin group only recovered after 48, 48, and 96 h, respectively. The villus height level in the CM-Pal treatment group recovered at 3 d p.i. However, the recovery time of the other groups was longer（at least 5 d）. The CM-Pal prevention group had a better effect on weight gain than the other groups. This study suggested that CM-Pal may be an effective alternative to conventional antibiotics for the treatment and prevention of animal diarrhea caused by Salmonella.展开更多
This article examines a mathematical model to analyze the rotating flow of three-dimensional water based nanofluid over a convectively heated exponentially stretching sheet in the presence of transverse magnetic field...This article examines a mathematical model to analyze the rotating flow of three-dimensional water based nanofluid over a convectively heated exponentially stretching sheet in the presence of transverse magnetic field with additional effects of thermal radiation,Joule heating and viscous dissipation.Silver(Ag),copper(Cu),copper oxide(Cu O),aluminum oxide(Al_2O_3)and titanium dioxide(Ti O_2)have been taken under consideration as the nanoparticles and water(H_2O)as the base fluid.Using suitable similarity transformations,the governing partial differential equations(PDEs)of the modeled problem are transformed to the ordinary differential equations(ODEs).These ODEs are then solved numerically by applying the shooting method.For the particular situation,the results are compared with the available literature.The effects of different nanoparticles on the temperature distribution are also discussed graphically and numerically.It is witnessed that the skin friction coefficient is maximum for silver based nanofluid.Also,the velocity profile is found to diminish for the increasing values of the magnetic parameter.展开更多
The Cu Cr/1Cr18Ni9 Ti bi-metal materials were prepared by the solid-liquid bonding method. The microstructures, mechanical properties and formation mechanism of the bonding interface were studied. The results show tha...The Cu Cr/1Cr18Ni9 Ti bi-metal materials were prepared by the solid-liquid bonding method. The microstructures, mechanical properties and formation mechanism of the bonding interface were studied. The results show that there exists a serrated transition layer with a certain width at the interface of Cu Cr/1Cr18Ni9 Ti bi-metal materials, and the transition layer consists of Fe-based and Cu-based solid solutions. The elastic modulus and hardness reach the maximum values at the interface closing to the 1Cr18Ni9 Ti zone. The bonding temperature has a significant effect on the width and morphology of the transition layer. The interfacial bonding strength is at least 30% higher than that of the Cu Cr alloy, and the tensile fracture occurs at the side of the Cu Cr alloy rather than at the bonding interface.展开更多
基金Project(12JCYBJC32100)supported by the Tianjin Research Program of Application Foundation and Advanced Technology,ChinaProject([2013]693)supported by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry,China
文摘Creep and anelastic backflow behaviors of pure copper （4N Cu） with grain size dg=40 μm were investigated at low temperatures of T〈0.3Tm （Tm is melting point） and ultra-low creep rates of ε≤1×10^-10 s^-1 by a high strain-resolution measurement （the helicoid spring specimen technique）. Analysis of creep data was based on the scaling factors of creep curves instead of the conventional extrapolated steady-state creep rate. Power-law creep equation is suggested to be the best for describing the primary transient creep behavior, because the pre-parameter does not apparently change with elapsed time. The observed anelastic strains are 1/6 of the calculated elastic strains, and linear viscous behavior was identified from the logarithm plot of the anelastic strain rate versus anelastic strain （slope equals 1）. Therefore, the creep anelasticity is suggested to be due to the unbowing of there-dimensional network of dislocations.
基金financial support from the fund of State Key Laboratory of Powder Metallurgy,Central South University,China
文摘This review discussed the relationship among copper,human,and bacteria.Copper plays an important role in human immunity.Copper can boost human immune defense reactions at recommended intake level.The content mainly focused on copper antibacterial activity and copper antibacterial mechanisms.Conclusions stated that copper antibacterial activity is affected by copper homeostasis mechanisms in bacteria,adhesion,humidity,strain specificity,and manufacturing methods of antibacterial agents.For the preparation of particle antibacterial agents and surface antibacterial agents,this review discussed several manufacturing methods,such as sol−gel,cold spray,and biosynthesis belonging to chemical synthesis,physical synthesis,and biological synthesis,respectively.Sol−gel method contributes to the preparation of particle agents and surface agents.Cold spray technique is utilized in synthesis of surface copper agent.Biosynthesis is a novel technology which can be applied in nanoparticle agent preparation.
基金supported by the Foundation of Chongqing Science and Technology Commission (Grant Nos.CSTC2009AC4187,CSTC2008BB4408)
文摘A1N is used as high power LED package material because of its excellent thermal conductivity. But its poor adhesive with metal is not compatible with the later processing sequence. The properties of the bonding between the deposited palladium, silver, copper and the clean Al-terminated （0001） surface of wurtzite AIN are investigated by using the density-functional the- ory. The results show that the sites of deposited metal atoms on N site are more stable than that on A1 site. Relaxations are found at all the studied interfaces. The bonding energies of Pd/A1N, Ag/A1N and Cu/A1N are respectively 2.75, 1.98, 2.26 eV. Hybridizations of s orbit and p orbit of the deposited metal atoms are observed, which contributes to the bonding energy of interface. The moving to lower energy state of the d orbit and the easier transfer of electrons to semi-empty d orbit in the case of deposited Pd results in the higher bonding energy of Pd/A1N interface.
基金supported by the Foundation of Key Laboratory for Palygorskite Science and Applied Technology of Jiangsu Province(No.HPK201506)the Natural Science Foundation of Jiangsu Province(No.BK20130686)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD),China
文摘The aim of this research was to develop effective alternative therapies to reduce antibiotic use in animal agriculture. In this study, the efficacy of copper-modified palygorskite（CM-Pal） in preventing diarrhea caused by Salmonella was specifically examined both in vitro and in vivo. The CM-Pal was prepared with palygorskite（Pal） and copper nitrate. The antibacterial activity of the CM-Pal was detected by comparing the differences in cell numbers on plate count agar before and after adding the CM-Pal to Salmonella typhimurium cultures. Seventy ICR mice were then allocated into seven groups. Five groups（the treatment groups） were infected with S. typhimurium by intraperitoneal（i.p.） injection and were given Pal, CM-Pal, montmorillonite powder, gentamicin, and physiological saline, respectively. One group（the prevention group） was given CM-Pal before infection with S. typhimurium. Another group（the uninfected group） was not infected with S. typhimurium. The effects of Pal, CM-Pal, montmorillonite powder, and gentamicin on the treatment or prevention of diarrhea in the mice were examined by stool studies, fecal scoring, and assessment of growth performance and villus height. The CM-Pal had satisfactory anti-bacterial properties in vitro： the antibacterial rate was 100% after 2 h incubation with S. typhimurium NJS1 cultures（1×10-6 colony-forming units（CFU）/ml）. In the in vivo experiment, the CM-Pal exerted superior effects in the treatment and prevention of diarrhea in mice compared with Pal, montmorillonite powder, and gentamicin. In the CM-Pal group, no mice showed signs of diarrhea at 24 h post infection（p.i.）, and all mice fully recovered from infection. However, the Pal group, montmorillonite group, and gentamicin group only recovered after 48, 48, and 96 h, respectively. The villus height level in the CM-Pal treatment group recovered at 3 d p.i. However, the recovery time of the other groups was longer（at least 5 d）. The CM-Pal prevention group had a better effect on weight gain than the other groups. This study suggested that CM-Pal may be an effective alternative to conventional antibiotics for the treatment and prevention of animal diarrhea caused by Salmonella.
文摘This article examines a mathematical model to analyze the rotating flow of three-dimensional water based nanofluid over a convectively heated exponentially stretching sheet in the presence of transverse magnetic field with additional effects of thermal radiation,Joule heating and viscous dissipation.Silver(Ag),copper(Cu),copper oxide(Cu O),aluminum oxide(Al_2O_3)and titanium dioxide(Ti O_2)have been taken under consideration as the nanoparticles and water(H_2O)as the base fluid.Using suitable similarity transformations,the governing partial differential equations(PDEs)of the modeled problem are transformed to the ordinary differential equations(ODEs).These ODEs are then solved numerically by applying the shooting method.For the particular situation,the results are compared with the available literature.The effects of different nanoparticles on the temperature distribution are also discussed graphically and numerically.It is witnessed that the skin friction coefficient is maximum for silver based nanofluid.Also,the velocity profile is found to diminish for the increasing values of the magnetic parameter.
基金supported by the National Natural Science Foundation of China(Grant No.51371139)Science and Technique Innovation Program of Shaanxi Province(Grant No.2012KTCQ01-14)+1 种基金Pivot Innovation Team of Shaanxi Electric Materials and the Infiltration Technique(Grant No.2012KCT-25)Shaanxi Provincial Project of Special Foundation of Key Disciplines
文摘The Cu Cr/1Cr18Ni9 Ti bi-metal materials were prepared by the solid-liquid bonding method. The microstructures, mechanical properties and formation mechanism of the bonding interface were studied. The results show that there exists a serrated transition layer with a certain width at the interface of Cu Cr/1Cr18Ni9 Ti bi-metal materials, and the transition layer consists of Fe-based and Cu-based solid solutions. The elastic modulus and hardness reach the maximum values at the interface closing to the 1Cr18Ni9 Ti zone. The bonding temperature has a significant effect on the width and morphology of the transition layer. The interfacial bonding strength is at least 30% higher than that of the Cu Cr alloy, and the tensile fracture occurs at the side of the Cu Cr alloy rather than at the bonding interface.
