A simple and convenient method, free of template, has been proposed to synthesize hollow carambolashaped Ag2 S microspheres with Ag NO3, thiourea（TU）, Na Cl and diethanolamine as reagents using a microwave-assisted ...A simple and convenient method, free of template, has been proposed to synthesize hollow carambolashaped Ag2 S microspheres with Ag NO3, thiourea（TU）, Na Cl and diethanolamine as reagents using a microwave-assisted method, at low temperatures of below 100 ℃. Powder X-ray diffraction（XRD）,scanning electron microscopy（FESEM） and high resolution transmission electron microscopy（HRTEM）were employed to characterize the morphology and composition of those microspheres. The results indicated that the hollow carambola-shaped silver sulfide microspheres（with high purity and homogeneous morphology） were prepared by an Ostwald ripening process. A possible formation mechanism of hollow carambola-shaped Ag2 S microspheres was proposed.展开更多
A wet-chemical method was presented for preparation of spherical, flowerlike, hexagonal, and triangular microsized silver crystals. Well-defined particles were prepared by mixing of iron（II） sulfate heptahydrate sol...A wet-chemical method was presented for preparation of spherical, flowerlike, hexagonal, and triangular microsized silver crystals. Well-defined particles were prepared by mixing of iron（II） sulfate heptahydrate solution with silver nitrate solution at the presence of different modifiers with high-speed stirring at 8-20℃. It is found that the diameters of resulting products are 0.6-6.0 um and the morphologies of the silver microcrystals are greatly affected by the introduced modifiers. It is concluded that the microsized silver crystals with different morphologies can be synthesized by introducing appropriate modifiers at appropriate experimental parameters. Scanning electron microscopy and X-ray diffraction were used to characterize the resulting products.展开更多
Silver nanoplates were synthesized in aqueous solution by photoinduced chemical reduction method with tungsten lamp as light source.The growth process was analyzed and characterized.The linear absorption spectra showe...Silver nanoplates were synthesized in aqueous solution by photoinduced chemical reduction method with tungsten lamp as light source.The growth process was analyzed and characterized.The linear absorption spectra showed that,along with the growth process,the surface plasmon resonance of silver seed nanoparticles at 395 nm decreased gradually,while a new plasmon band at 740 nm corresponding to silver nanoplates appeared and increased gradually.Z-scan technique was used to explore the nonlinear optical properties of silver nanoplates.The results displayed that with the reaction time increases from 0 h to 24 h,the value of nonlinear absorption（NLA） coefficient and the value of nonlinear refraction（NLR） index of the products increased from 0 to 3.167 cm/GW and from 0.64×10^ 4 to 6.83×10 ^4 cm 2 /GW,respectively.展开更多
NT build 443, or profile fitting method, is often used to measure the diffusion coefficient of chloride in concrete. However, this method is quite laborious and needs special equipment. Colorimetric method is a quick ...NT build 443, or profile fitting method, is often used to measure the diffusion coefficient of chloride in concrete. However, this method is quite laborious and needs special equipment. Colorimetric method is a quick and simple method to measure the penetration depth of chloride by spraying 0.1 mol/L silver nitrate solution. The objective of this work is to study the possibility of the use of colorimetric method in the calculation of non-steady-state diffusion coefficient. Twelve concrete mixtures with different supplementary cementitious materials and water-to-cement ratios of 0.35, 0.48 and 0.6 were used for study. According to NT build 443, the concrete specimens were immersed in 165 g/L NaC1 （2.8 mol/L） solution for 42 d. Both water-soluble （convert to free chloride） chloride and acid-soluble chloride at different layers of specimens were measured. The results show that the mean value of free chloride concentration at the color change boundary Cd was 0.306 mol/L. The surface free chloride concentration cs was obtained by profile fitting method, which was 40% lower than the chloride concentration of exposure solution after an immersion period of 42 d. Chloride diffusion coefficients obtained by the colorimetric method was not well correlated with those obtained by profile fitting method.展开更多
Silver-tin oxide composite powders and silver powders were synthesized by hydrothermal method using NH3 to complex Ag+, SO 32?to reduce Ag (NH3)+2 and Na2SnO3 as the source of tin. The powders were characterized by XR...Silver-tin oxide composite powders and silver powders were synthesized by hydrothermal method using NH3 to complex Ag+, SO 32?to reduce Ag (NH3)+2 and Na2SnO3 as the source of tin. The powders were characterized by XRD, SEM and EDX. The results show that there are macroscopic and microscopic differences between two kinds of powders. Spherical silver powders are 3 μm in diameter, and silver-tin oxide composite powders are mainly flake of about 0.3 μm in thickness. Silver crystal in silver-tin oxide composite powders is preferentially oriented in the (111) crystallographic direction and its oriented index is 2.581. Crystal lattice parameter of silver crystal of silver tin-oxide composite powders is 0.409 34 nm, larger than 0.408 68 nm of silver powders. The XPS analysis shows that silver in silver-tin oxide composite powders is metallic silver and tin oxide in silver tin-oxide composite powders has the red shift for Sn4+(3d5/2) and O2-(1s).展开更多
Shaped silver nanoparticles with sphere, wire and dendrite were prepared by sonoelectrochemical deposition from an aqueous solution of AgNO3 in the presence of ethylenediaminetetraacetic acid disodium salt （EDTA） an...Shaped silver nanoparticles with sphere, wire and dendrite were prepared by sonoelectrochemical deposition from an aqueous solution of AgNO3 in the presence of ethylenediaminetetraacetic acid disodium salt （EDTA） and polyvinylpyrrolidone （PVP）. The diameter of spherical silver particles was about 30 nm. The diameter of the silver nanowires was also about 30 nm and the length was 200-900 nm. The dendrites were synthesized with the concentration of silver solution increasing. Silver nanoparticles were characterized by transmission electron microscope （TEM）, X-ray powder diffraction （XRD）, scanning probe microscope （SPM） and UV-vis absorption spectrum. XRD patterns revealed that silver particles were of face-centered cubic structure. UV-vis absorption spectra indicated that different morphology and size of silver particles could influence the optical properties.展开更多
Silver tin oxide composite powders were synthesized by the hydrothermal method with a silver ammine solution and a Na2SnO3 solution as raw materials. H2C2O4 was used as the co-precipitator of silver ions and tin ions....Silver tin oxide composite powders were synthesized by the hydrothermal method with a silver ammine solution and a Na2SnO3 solution as raw materials. H2C2O4 was used as the co-precipitator of silver ions and tin ions. The co-precipitation conditions were investigated. The results show that the co-precipitate of Ag2C2O4 and Sn（OH）4 is available when the pH value of the solution is 4.27-8.36. Using the obtained precipitate as precursor,the reduction of Ag＋ and the crystallization of tin oxide were carried out simultaneously by the hydrothermal method and silver tin oxide composite powders were obtained. The composite powders were characterized by X-ray diffraction （XRD） analysis,scanning electron microscope （SEM）,and energy spectrum analysis. The results show that the silver tin oxide composite powders are small with a diameter of about 2 μm and with homogeneous distribution of tin.展开更多
The title compound [Ag(CH3CONHC(S)NH2)2](NO3) has been prepared by hydrothermal synthesis and characterized by single-crystal X-ray diffraction. It crystallizes in mo-noclinic, space group P21/c with Mr = 406.20 (C6H1...The title compound [Ag(CH3CONHC(S)NH2)2](NO3) has been prepared by hydrothermal synthesis and characterized by single-crystal X-ray diffraction. It crystallizes in mo-noclinic, space group P21/c with Mr = 406.20 (C6H12Ag N5O5S2), a = 12.0680(6), b = 6.8056(5), c = 18.0173(1) ? b = 111.383(4), V = 1377.9(2) 3, Z = 4, Dc = 1.958 g/cm3 , F(000) = 808, = 1.789 mm-1, R = 0.0361 and wR = 0.1015. Of 4185 reflections ((2)max = 55.00?, 3147 were unique (Rint = 0.0174) and 2820 with I > 2(I) were used to solve the structure. The silver(I) atom adopts V-shape geometry with the AgS bond distance of 2.4271(7) and 2.7229(9) , respectively. Seven atoms of one acetylthiocarbamide ligand are coplanar, while only four atoms of another acetylthio-carbamide ligand are fairly planar. The [Ag(CH3CONHC(S)NH2)2]+ cation and nitrate anion NO3- are connected by hydrogen bonds to form a three dimensional hydrogen bonding network..展开更多
Silver nanoparticles were synthesized using eco-friendly method with extract of Carica papaya as reducing and stabilizing agent. The silver precursor used was silver nitrate solution. A visible colour change from colo...Silver nanoparticles were synthesized using eco-friendly method with extract of Carica papaya as reducing and stabilizing agent. The silver precursor used was silver nitrate solution. A visible colour change from colourless to reddish brown confirmed the formation of the nanoparticles and the UV-Vis spectroscopy showed surface plasmon resonance of 435 nm for the silver nanoparticle. The mean particle size was 250 nm while the polydispersity index was 0.22. The antimicrobial activity of the synthesized nanoparticles was studied against Pseudomonas aeruginosa, Escherichia coli, Bacillus subtilis and Staphylococcus aureus. The silver nanoparticles biosynthesized showed satisfactory antimicrobial activity against the test isolates. Antimicrobial property of the nanoparticles was similar (P > 0.05). Generally, MIC values of the samples against the microorganisms tested ranged from 25 - 100 mg/ml. Pseudomonas aeruginosa was most sensitive while Staphylococcus aureus and Bacillus subtilis were least sensitive to the silver nanoparticles.展开更多
Lung smears of mice and lung sections of rats or human case with Pneumocystis cariniiinfection were stained using the Grocott's modification method of Gomori's methenamine-silver nitratetechnic, in which 5% so...Lung smears of mice and lung sections of rats or human case with Pneumocystis cariniiinfection were stained using the Grocott's modification method of Gomori's methenamine-silver nitratetechnic, in which 5% sodium periodate and 5% chromic acid were used as oxidant respectively. Theoxidation time for the mouse lung smears was 5,15,60 minutes and the oxidation temperature was 20℃.The time of silver impregnation was 90 minutcs and the temperature was 60℃ for the all smearo. Whenthe oxidation time was under 15 minutes. Pneumocystis cariniic cysts showed light or dark brown, and theparenthesis-like structure could clearly be found in part of the cysts. However, if the time of oxidationWas longer, the cysts showed black and secmed to have damaged. In the same batch of the mouse lungsmears oxidated for 5 minutes, the samiples oxidated by sodium periodate showed more the cysts with theparen thesis-like structure than those oxidated by chromic acid.In the rat or patient's lung sectionsoxidated by. sodium periodate, this structure could also be found. The result of the experiment showsthat sodium periodate as an oxidant in the subsequent step of the the silver impregnation is preferable tochromic acid. And then,it is useful to clinical practice that the step of sodium bisulfate can be omittedin the study.展开更多
基金supported by the Fundamental Research Funds for the Central Universities(No.2232013A3-05)the National Science and Technology Ministry(No.ID 2012BAK30B03)
文摘A simple and convenient method, free of template, has been proposed to synthesize hollow carambolashaped Ag2 S microspheres with Ag NO3, thiourea（TU）, Na Cl and diethanolamine as reagents using a microwave-assisted method, at low temperatures of below 100 ℃. Powder X-ray diffraction（XRD）,scanning electron microscopy（FESEM） and high resolution transmission electron microscopy（HRTEM）were employed to characterize the morphology and composition of those microspheres. The results indicated that the hollow carambola-shaped silver sulfide microspheres（with high purity and homogeneous morphology） were prepared by an Ostwald ripening process. A possible formation mechanism of hollow carambola-shaped Ag2 S microspheres was proposed.
文摘A wet-chemical method was presented for preparation of spherical, flowerlike, hexagonal, and triangular microsized silver crystals. Well-defined particles were prepared by mixing of iron（II） sulfate heptahydrate solution with silver nitrate solution at the presence of different modifiers with high-speed stirring at 8-20℃. It is found that the diameters of resulting products are 0.6-6.0 um and the morphologies of the silver microcrystals are greatly affected by the introduced modifiers. It is concluded that the microsized silver crystals with different morphologies can be synthesized by introducing appropriate modifiers at appropriate experimental parameters. Scanning electron microscopy and X-ray diffraction were used to characterize the resulting products.
基金Supported by the National Natural Science Foundation of China(11174229)
文摘Silver nanoplates were synthesized in aqueous solution by photoinduced chemical reduction method with tungsten lamp as light source.The growth process was analyzed and characterized.The linear absorption spectra showed that,along with the growth process,the surface plasmon resonance of silver seed nanoparticles at 395 nm decreased gradually,while a new plasmon band at 740 nm corresponding to silver nanoplates appeared and increased gradually.Z-scan technique was used to explore the nonlinear optical properties of silver nanoplates.The results displayed that with the reaction time increases from 0 h to 24 h,the value of nonlinear absorption（NLA） coefficient and the value of nonlinear refraction（NLR） index of the products increased from 0 to 3.167 cm/GW and from 0.64×10^ 4 to 6.83×10 ^4 cm 2 /GW,respectively.
基金Project(2010QZZD018) supported by Central South Universtiy,China,and Ghent University,Belgium
文摘NT build 443, or profile fitting method, is often used to measure the diffusion coefficient of chloride in concrete. However, this method is quite laborious and needs special equipment. Colorimetric method is a quick and simple method to measure the penetration depth of chloride by spraying 0.1 mol/L silver nitrate solution. The objective of this work is to study the possibility of the use of colorimetric method in the calculation of non-steady-state diffusion coefficient. Twelve concrete mixtures with different supplementary cementitious materials and water-to-cement ratios of 0.35, 0.48 and 0.6 were used for study. According to NT build 443, the concrete specimens were immersed in 165 g/L NaC1 （2.8 mol/L） solution for 42 d. Both water-soluble （convert to free chloride） chloride and acid-soluble chloride at different layers of specimens were measured. The results show that the mean value of free chloride concentration at the color change boundary Cd was 0.306 mol/L. The surface free chloride concentration cs was obtained by profile fitting method, which was 40% lower than the chloride concentration of exposure solution after an immersion period of 42 d. Chloride diffusion coefficients obtained by the colorimetric method was not well correlated with those obtained by profile fitting method.
文摘Silver-tin oxide composite powders and silver powders were synthesized by hydrothermal method using NH3 to complex Ag+, SO 32?to reduce Ag (NH3)+2 and Na2SnO3 as the source of tin. The powders were characterized by XRD, SEM and EDX. The results show that there are macroscopic and microscopic differences between two kinds of powders. Spherical silver powders are 3 μm in diameter, and silver-tin oxide composite powders are mainly flake of about 0.3 μm in thickness. Silver crystal in silver-tin oxide composite powders is preferentially oriented in the (111) crystallographic direction and its oriented index is 2.581. Crystal lattice parameter of silver crystal of silver tin-oxide composite powders is 0.409 34 nm, larger than 0.408 68 nm of silver powders. The XPS analysis shows that silver in silver-tin oxide composite powders is metallic silver and tin oxide in silver tin-oxide composite powders has the red shift for Sn4+(3d5/2) and O2-(1s).
基金[This work was financially supported by the National Natural Science Foundation of China (No. 50271046).]
文摘Shaped silver nanoparticles with sphere, wire and dendrite were prepared by sonoelectrochemical deposition from an aqueous solution of AgNO3 in the presence of ethylenediaminetetraacetic acid disodium salt （EDTA） and polyvinylpyrrolidone （PVP）. The diameter of spherical silver particles was about 30 nm. The diameter of the silver nanowires was also about 30 nm and the length was 200-900 nm. The dendrites were synthesized with the concentration of silver solution increasing. Silver nanoparticles were characterized by transmission electron microscope （TEM）, X-ray powder diffraction （XRD）, scanning probe microscope （SPM） and UV-vis absorption spectrum. XRD patterns revealed that silver particles were of face-centered cubic structure. UV-vis absorption spectra indicated that different morphology and size of silver particles could influence the optical properties.
文摘Silver tin oxide composite powders were synthesized by the hydrothermal method with a silver ammine solution and a Na2SnO3 solution as raw materials. H2C2O4 was used as the co-precipitator of silver ions and tin ions. The co-precipitation conditions were investigated. The results show that the co-precipitate of Ag2C2O4 and Sn（OH）4 is available when the pH value of the solution is 4.27-8.36. Using the obtained precipitate as precursor,the reduction of Ag＋ and the crystallization of tin oxide were carried out simultaneously by the hydrothermal method and silver tin oxide composite powders were obtained. The composite powders were characterized by X-ray diffraction （XRD） analysis,scanning electron microscope （SEM）,and energy spectrum analysis. The results show that the silver tin oxide composite powders are small with a diameter of about 2 μm and with homogeneous distribution of tin.
基金This work was supported by the Natural Science Foundation of Shandong province (No.Y2002B06) and Science Research Foundation of Qingdao University of Science and Technology (No. 03Z08)
文摘The title compound [Ag(CH3CONHC(S)NH2)2](NO3) has been prepared by hydrothermal synthesis and characterized by single-crystal X-ray diffraction. It crystallizes in mo-noclinic, space group P21/c with Mr = 406.20 (C6H12Ag N5O5S2), a = 12.0680(6), b = 6.8056(5), c = 18.0173(1) ? b = 111.383(4), V = 1377.9(2) 3, Z = 4, Dc = 1.958 g/cm3 , F(000) = 808, = 1.789 mm-1, R = 0.0361 and wR = 0.1015. Of 4185 reflections ((2)max = 55.00?, 3147 were unique (Rint = 0.0174) and 2820 with I > 2(I) were used to solve the structure. The silver(I) atom adopts V-shape geometry with the AgS bond distance of 2.4271(7) and 2.7229(9) , respectively. Seven atoms of one acetylthiocarbamide ligand are coplanar, while only four atoms of another acetylthio-carbamide ligand are fairly planar. The [Ag(CH3CONHC(S)NH2)2]+ cation and nitrate anion NO3- are connected by hydrogen bonds to form a three dimensional hydrogen bonding network..
文摘Silver nanoparticles were synthesized using eco-friendly method with extract of Carica papaya as reducing and stabilizing agent. The silver precursor used was silver nitrate solution. A visible colour change from colourless to reddish brown confirmed the formation of the nanoparticles and the UV-Vis spectroscopy showed surface plasmon resonance of 435 nm for the silver nanoparticle. The mean particle size was 250 nm while the polydispersity index was 0.22. The antimicrobial activity of the synthesized nanoparticles was studied against Pseudomonas aeruginosa, Escherichia coli, Bacillus subtilis and Staphylococcus aureus. The silver nanoparticles biosynthesized showed satisfactory antimicrobial activity against the test isolates. Antimicrobial property of the nanoparticles was similar (P > 0.05). Generally, MIC values of the samples against the microorganisms tested ranged from 25 - 100 mg/ml. Pseudomonas aeruginosa was most sensitive while Staphylococcus aureus and Bacillus subtilis were least sensitive to the silver nanoparticles.
文摘Lung smears of mice and lung sections of rats or human case with Pneumocystis cariniiinfection were stained using the Grocott's modification method of Gomori's methenamine-silver nitratetechnic, in which 5% sodium periodate and 5% chromic acid were used as oxidant respectively. Theoxidation time for the mouse lung smears was 5,15,60 minutes and the oxidation temperature was 20℃.The time of silver impregnation was 90 minutcs and the temperature was 60℃ for the all smearo. Whenthe oxidation time was under 15 minutes. Pneumocystis cariniic cysts showed light or dark brown, and theparenthesis-like structure could clearly be found in part of the cysts. However, if the time of oxidationWas longer, the cysts showed black and secmed to have damaged. In the same batch of the mouse lungsmears oxidated for 5 minutes, the samiples oxidated by sodium periodate showed more the cysts with theparen thesis-like structure than those oxidated by chromic acid.In the rat or patient's lung sectionsoxidated by. sodium periodate, this structure could also be found. The result of the experiment showsthat sodium periodate as an oxidant in the subsequent step of the the silver impregnation is preferable tochromic acid. And then,it is useful to clinical practice that the step of sodium bisulfate can be omittedin the study.
