Carbon nanotubes （CNTs） were coated by tungsten using metal organic chemical vapor deposition. Magnetic stirring was employed to disperse the W-coated CNTs （W-CNTs） in a Cu matrix, and then, the mixed powders were...Carbon nanotubes （CNTs） were coated by tungsten using metal organic chemical vapor deposition. Magnetic stirring was employed to disperse the W-coated CNTs （W-CNTs） in a Cu matrix, and then, the mixed powders were consolidated by spark plasma sintering. The W-CNTs obtained a uniform dispersion within the Cu matrix when the W-CNT content was less than 5.0vo1%, but high content of W-CNTs （10vol%） resulted in the presence of clusters. The W-CNT/Cu composites containing low content of W-CNTs （〈5.0vol%） exhibited a higher thermal conductivity than the sintered pure Cu, while the CNT/Cu composites exhibited no increase in thermal conductivity after the incorporation of uncoated CNTs. The W-CNT content was found to play a crucial role in determining the thermal conductivity of the W-CNT/Cu composites. The thermal conductivity of the W-CNT/Cu composites increased first and then decreased with the W-CNT content increasing. When the W-CNT content was 2.5vo1%, the W-CNT/Cu composite obtained the maximum value of thermal conductivity. The thermal resistance of the （W-CNT）-Cu interface was predicted in terms of Maxwell-Gamett effective medium approximation, and its calculated value was about 3.0× 10-9 m2.K.W-l.展开更多
Nickel and chromium coatings were produced using plasma spraying and laser remelting on the copper sheet. The corrosion test was carried out in an acidic atmosphere, and the corrosive behaviors of both coatings and or...Nickel and chromium coatings were produced using plasma spraying and laser remelting on the copper sheet. The corrosion test was carried out in an acidic atmosphere, and the corrosive behaviors of both coatings and original copper samples were investigated by using an impedance comparison method. Experimental results show that nickel and chromium coatings display better corrosion resistance properties relative to the original pure copper sample. The corrosion rate of chromium coating is less than that of nickel coating, and corrosion resistances of laser remelted nickel and chromium samples are better than those of plasma sprayed samples. The corrosion deposit film of copper is loose compared with nickel and chromium.展开更多
Dielectric barrier discharge （DBD） cold plasma at atmospheric pressure was used for preparation of copper nanoparticles by reduction of copper oxide （CuO）. Power X-ray diffraction （XRD） was used to characterize ...Dielectric barrier discharge （DBD） cold plasma at atmospheric pressure was used for preparation of copper nanoparticles by reduction of copper oxide （CuO）. Power X-ray diffraction （XRD） was used to characterize the structure of the copper oxide samples treated by DBD plasma. Influences of H2 content and the treating time on the reduction of copper oxide by DBD plasma were investigated. The results show that the reduction ratio of copper oxide was increased initially and then decreased with increasing H2 content, and the highest reduction ratio was achieved at 20% H2 content. Moreover, the copper oxide samples were gradually reduced by DBD plasma into copper nanoparticles with the increase in treating time. However, the average reduction rate was decreased as a result of the diffusion of the active hydrogen species. Optical emission spectra （OES） were observed during the reduction of the copper oxide samples by DBD plasma, and the reduction mechanism was explored accordingly. Instead of high-energy electrons, atomic hydrogen （H） radicals, and the heating effect, excited-state hydrogen molecules are suspected to be one kind of important reducing agents. Atmospheric-pressure DBD cold plasma is proved to be an efficient method for preparing copper nanoparticles.展开更多
The objectives of this study were to study the effects of different levels of dietary copper on copper and zinc balance, plasma minerals and serum biochemical parameters of mink in the growing-furring periods. One hun...The objectives of this study were to study the effects of different levels of dietary copper on copper and zinc balance, plasma minerals and serum biochemical parameters of mink in the growing-furring periods. One hundred and five standard dark male mink were randomly assigned to seven groups with the following dietary treatments: basal diet with no supplemental Cu(Control); basal diet supplemented with either 6,12, 24, 48, 96, or 192 mg/kg Cu from copper sulfate,respectively. The average daily gain(ADG) linearly(P = 0.0026, P = 0.0006) responded to increasing levels of Cu; maximal growth was seen in the Cu24 group. Feed efficiency tended to improve with the increase of dietary copper level(linear P = 0.0010, quad, P = 0.0011). Fecal copper, urinary copper, retention copper responded in a linear(P < 0.05) fashion with increasing level of Cu. The effect of level of Cu was linear(P < 0.001) for plasma Cu concentration. The serum glutamic-oxalacetic transaminase(GOT) and glutamic-pyruvic transaminase(GPT) activities were increased linearly(P < 0.05) with dose of Cu, but serum total protein(TP) and albumin(ALB) concentrations decreased linearly(P < 0.05) as dietary copper levels increased. Effect of level of Cu was linear(P < 0.001) for serum ceruloplasmin(CER) concentration or Cu-Zn superoxide dismutase(Cu-Zn SOD) activity. Supplemental dose of Cu linearly decreased serum triglyceride(TG)(P = 0.011) and total cholesterol(TC)(P = 0.007). Our results indicated that the activity of Cu-dependent enzymes was enhanced by increasing dietary Cu concentration and that supplementation of Cu in the diet of mink could alter the plasma lipid profile and copper concentration.展开更多
Non-thermal plasma(NTP)surface modification technology is a new method to control the surface properties of materials,which has been widely used in the field of environmental protection because of its short action tim...Non-thermal plasma(NTP)surface modification technology is a new method to control the surface properties of materials,which has been widely used in the field of environmental protection because of its short action time,simple process and no pollution.In this study,Cu/ACF(activated carbon fiber loaded with copper)adsorbent was modified with NTP to remove H_(2)S and PH_(3) simultaneously under low temperature and micro-oxygen condition.Meanwhile,the effects of different modified atmosphere(air,N_(2) and NH_(3)),specific energy input(0–13 J/mL)and modification time(0–30 min)on the removal of H_(2)S and PH_(3) were investigated.Performance test results indicated that under the same reaction conditions,the adsorbent modified by NH_(3) plasma with 5 J/mL for 10 min had the best removal effect on H_(2)S and PH_(3).CO_(2) temperature-programmed desorption and X-ray photoelectron spectroscopy(XPS)analyzes showed that NH_(3) plasma modification could introduce amino functional groups on the surface of the adsorbent,and increase the types and number of alkaline sites on the surface.Brunauer-Emmett-Teller and scanning electron microscopy showed that NH_(3) plasma modification did not significantly change the pore size structure of the adsorbent,but more active components were evenly exposed to the surface,thus improving the adsorption performance.In addition,X-ray diffraction and XPS analysis indicated that the consumption of active components(Cu and Cu_(2)O)and the accumulation of sulfate and phosphate on the surface and inner pores of the adsorbent are the main reasons for the deactivation of the adsorbent.展开更多
基金supported by the National High-Tech Research and Development Program of China (No.2009AA03Z116)the National Natural Science Foundation of China (No.50971020)
文摘Carbon nanotubes （CNTs） were coated by tungsten using metal organic chemical vapor deposition. Magnetic stirring was employed to disperse the W-coated CNTs （W-CNTs） in a Cu matrix, and then, the mixed powders were consolidated by spark plasma sintering. The W-CNTs obtained a uniform dispersion within the Cu matrix when the W-CNT content was less than 5.0vo1%, but high content of W-CNTs （10vol%） resulted in the presence of clusters. The W-CNT/Cu composites containing low content of W-CNTs （〈5.0vol%） exhibited a higher thermal conductivity than the sintered pure Cu, while the CNT/Cu composites exhibited no increase in thermal conductivity after the incorporation of uncoated CNTs. The W-CNT content was found to play a crucial role in determining the thermal conductivity of the W-CNT/Cu composites. The thermal conductivity of the W-CNT/Cu composites increased first and then decreased with the W-CNT content increasing. When the W-CNT content was 2.5vo1%, the W-CNT/Cu composite obtained the maximum value of thermal conductivity. The thermal resistance of the （W-CNT）-Cu interface was predicted in terms of Maxwell-Gamett effective medium approximation, and its calculated value was about 3.0× 10-9 m2.K.W-l.
基金The work was supported by the Research Grants Council of the Hong Kong Special Administrative Region of China under Grant No. PolyU 5171/01E
文摘Nickel and chromium coatings were produced using plasma spraying and laser remelting on the copper sheet. The corrosion test was carried out in an acidic atmosphere, and the corrosive behaviors of both coatings and original copper samples were investigated by using an impedance comparison method. Experimental results show that nickel and chromium coatings display better corrosion resistance properties relative to the original pure copper sample. The corrosion rate of chromium coating is less than that of nickel coating, and corrosion resistances of laser remelted nickel and chromium samples are better than those of plasma sprayed samples. The corrosion deposit film of copper is loose compared with nickel and chromium.
基金supported by National Natural Science Foundation of China(No.21173028)the Science and Technology Research Project of Liaoning Provincial Education Department of China(No.L2013464)the Scientific Research Foundation for the Doctor of Liaoning Province of China(No.20131004)
文摘Dielectric barrier discharge （DBD） cold plasma at atmospheric pressure was used for preparation of copper nanoparticles by reduction of copper oxide （CuO）. Power X-ray diffraction （XRD） was used to characterize the structure of the copper oxide samples treated by DBD plasma. Influences of H2 content and the treating time on the reduction of copper oxide by DBD plasma were investigated. The results show that the reduction ratio of copper oxide was increased initially and then decreased with increasing H2 content, and the highest reduction ratio was achieved at 20% H2 content. Moreover, the copper oxide samples were gradually reduced by DBD plasma into copper nanoparticles with the increase in treating time. However, the average reduction rate was decreased as a result of the diffusion of the active hydrogen species. Optical emission spectra （OES） were observed during the reduction of the copper oxide samples by DBD plasma, and the reduction mechanism was explored accordingly. Instead of high-energy electrons, atomic hydrogen （H） radicals, and the heating effect, excited-state hydrogen molecules are suspected to be one kind of important reducing agents. Atmospheric-pressure DBD cold plasma is proved to be an efficient method for preparing copper nanoparticles.
基金Special Fund for Agro-scientific Research in the Public Interest(No.200903014)
文摘The objectives of this study were to study the effects of different levels of dietary copper on copper and zinc balance, plasma minerals and serum biochemical parameters of mink in the growing-furring periods. One hundred and five standard dark male mink were randomly assigned to seven groups with the following dietary treatments: basal diet with no supplemental Cu(Control); basal diet supplemented with either 6,12, 24, 48, 96, or 192 mg/kg Cu from copper sulfate,respectively. The average daily gain(ADG) linearly(P = 0.0026, P = 0.0006) responded to increasing levels of Cu; maximal growth was seen in the Cu24 group. Feed efficiency tended to improve with the increase of dietary copper level(linear P = 0.0010, quad, P = 0.0011). Fecal copper, urinary copper, retention copper responded in a linear(P < 0.05) fashion with increasing level of Cu. The effect of level of Cu was linear(P < 0.001) for plasma Cu concentration. The serum glutamic-oxalacetic transaminase(GOT) and glutamic-pyruvic transaminase(GPT) activities were increased linearly(P < 0.05) with dose of Cu, but serum total protein(TP) and albumin(ALB) concentrations decreased linearly(P < 0.05) as dietary copper levels increased. Effect of level of Cu was linear(P < 0.001) for serum ceruloplasmin(CER) concentration or Cu-Zn superoxide dismutase(Cu-Zn SOD) activity. Supplemental dose of Cu linearly decreased serum triglyceride(TG)(P = 0.011) and total cholesterol(TC)(P = 0.007). Our results indicated that the activity of Cu-dependent enzymes was enhanced by increasing dietary Cu concentration and that supplementation of Cu in the diet of mink could alter the plasma lipid profile and copper concentration.
基金funding for this study received from the Fundamental Research Funds for the National Natural Science Foundation of China(Nos.21876071,51968034,41807373 and 21667015)Science and Technology Program of Yunnan province(No.2019FB069).
文摘Non-thermal plasma(NTP)surface modification technology is a new method to control the surface properties of materials,which has been widely used in the field of environmental protection because of its short action time,simple process and no pollution.In this study,Cu/ACF(activated carbon fiber loaded with copper)adsorbent was modified with NTP to remove H_(2)S and PH_(3) simultaneously under low temperature and micro-oxygen condition.Meanwhile,the effects of different modified atmosphere(air,N_(2) and NH_(3)),specific energy input(0–13 J/mL)and modification time(0–30 min)on the removal of H_(2)S and PH_(3) were investigated.Performance test results indicated that under the same reaction conditions,the adsorbent modified by NH_(3) plasma with 5 J/mL for 10 min had the best removal effect on H_(2)S and PH_(3).CO_(2) temperature-programmed desorption and X-ray photoelectron spectroscopy(XPS)analyzes showed that NH_(3) plasma modification could introduce amino functional groups on the surface of the adsorbent,and increase the types and number of alkaline sites on the surface.Brunauer-Emmett-Teller and scanning electron microscopy showed that NH_(3) plasma modification did not significantly change the pore size structure of the adsorbent,but more active components were evenly exposed to the surface,thus improving the adsorption performance.In addition,X-ray diffraction and XPS analysis indicated that the consumption of active components(Cu and Cu_(2)O)and the accumulation of sulfate and phosphate on the surface and inner pores of the adsorbent are the main reasons for the deactivation of the adsorbent.
