A rapid method for the determination of impurity elements, such as Zn, Ni, Co, Cr, Cu, Cd and Pb in manganese tetroxide was developed, using inductively coupled plasma atomic emission spectrometry （ICP-AES）. The cri...A rapid method for the determination of impurity elements, such as Zn, Ni, Co, Cr, Cu, Cd and Pb in manganese tetroxide was developed, using inductively coupled plasma atomic emission spectrometry （ICP-AES）. The critical instrumental parameters such as sample flow rate and radio frequency incident were thoroughly optimized. The effect of matrix was also examined. The sensitivity was investigated using calibration curves obtained in presence of the matrix. The obtained recoveries for Ni, Co, Cr, Cu, and Cd at the μg· g^ -1 level were satisfactory and practically independent of the matrix used for the calibration standards. The recoveries of Pb and Zn were less suffwient. The method can be applied for routine analysis and quality control purposes at μg· g^-1 level of concentration.展开更多
Microphase separation and lamellar structure of segmented polyether- and polyester-polyurethanes have been investigated by means of transmission electron microscopy with the ruthenium tetroxide staining technique. The...Microphase separation and lamellar structure of segmented polyether- and polyester-polyurethanes have been investigated by means of transmission electron microscopy with the ruthenium tetroxide staining technique. The results show that the RuO_4 staining technique is simpler and may give better image contrast than other staining methods for this polymer. Microphase separation and lamellar structure of segmented polyether-and polyester-polyurethanes were directly observed and discussed.展开更多
Manganese tetroxide(Mn_(3)O_(4))nanofibers were prepared by electrospinning homogeneous viscous solution of 20 wt%,28 wt%and 36 wt%manganese acetate in poly vinyl alcohol(PVA)and calcining the nanofibers at 1000℃for ...Manganese tetroxide(Mn_(3)O_(4))nanofibers were prepared by electrospinning homogeneous viscous solution of 20 wt%,28 wt%and 36 wt%manganese acetate in poly vinyl alcohol(PVA)and calcining the nanofibers at 1000℃for 2 h.Electrospinning was carried out at 9 kV DC with tip to collector distance(TCD)of 7 cm.Thermo gravimetric analysis(TGA)of the fibers indicates the pure phase of manganese oxide above 500℃.XRD analysis of calcined(at 1000℃)nanofibers indicates the formation of phase-pure tetragonal Mn_(3)O_(4).Scanning electron microscopy(SEM)studies show the fibers cylindrical with the diameters in the range of 100-600 nm and aspect ratio>1000.In general,the average diameter of the green fibers decreases with the increase in manganese acetate concentration.The diameter of calcined nanofibers is reduced by 34%.展开更多
A new chiral polymer-metal complex, wool-osmium tetroxide(wool-OsO4) complex was prepared by a very simple method. This complex was found to be able to catalyze the asymmetric dihydroxylation of allylamine to get (R)-...A new chiral polymer-metal complex, wool-osmium tetroxide(wool-OsO4) complex was prepared by a very simple method. This complex was found to be able to catalyze the asymmetric dihydroxylation of allylamine to get (R)-(+)-3-amino-l, 2-propanediol. The experimental results showed that OsO4 content in the complex, reaction time, allylamine/OsO4 molar ratio all have great effects on the chemical and optical yields of product. Additionally, wool-OsO4 complex catalyst could be reused without remarkable change in optical catalytic activity.展开更多
基金Supported bythe financial support of Sino-Romanian GovernmentalInternational Science and Technology Cooperation Projeet( No.37-11)the Scientific and Technological Project of Tackle Key Problemin Science and Technology Branch of Hunan Province ( No.00GKY2020 +4 种基金01GKY2027 03GKY2022)Key Project of Hunan Pro-vincial Educational Branch(No.02A040) Key Project of RegionalUniversityin Chinese Ministry of Education(No.204103)and Fundfor Returned Overseas Scholars ,China University of Geosciences(No.XLX04901)
文摘A rapid method for the determination of impurity elements, such as Zn, Ni, Co, Cr, Cu, Cd and Pb in manganese tetroxide was developed, using inductively coupled plasma atomic emission spectrometry （ICP-AES）. The critical instrumental parameters such as sample flow rate and radio frequency incident were thoroughly optimized. The effect of matrix was also examined. The sensitivity was investigated using calibration curves obtained in presence of the matrix. The obtained recoveries for Ni, Co, Cr, Cu, and Cd at the μg· g^ -1 level were satisfactory and practically independent of the matrix used for the calibration standards. The recoveries of Pb and Zn were less suffwient. The method can be applied for routine analysis and quality control purposes at μg· g^-1 level of concentration.
文摘Microphase separation and lamellar structure of segmented polyether- and polyester-polyurethanes have been investigated by means of transmission electron microscopy with the ruthenium tetroxide staining technique. The results show that the RuO_4 staining technique is simpler and may give better image contrast than other staining methods for this polymer. Microphase separation and lamellar structure of segmented polyether-and polyester-polyurethanes were directly observed and discussed.
文摘Manganese tetroxide(Mn_(3)O_(4))nanofibers were prepared by electrospinning homogeneous viscous solution of 20 wt%,28 wt%and 36 wt%manganese acetate in poly vinyl alcohol(PVA)and calcining the nanofibers at 1000℃for 2 h.Electrospinning was carried out at 9 kV DC with tip to collector distance(TCD)of 7 cm.Thermo gravimetric analysis(TGA)of the fibers indicates the pure phase of manganese oxide above 500℃.XRD analysis of calcined(at 1000℃)nanofibers indicates the formation of phase-pure tetragonal Mn_(3)O_(4).Scanning electron microscopy(SEM)studies show the fibers cylindrical with the diameters in the range of 100-600 nm and aspect ratio>1000.In general,the average diameter of the green fibers decreases with the increase in manganese acetate concentration.The diameter of calcined nanofibers is reduced by 34%.
文摘A new chiral polymer-metal complex, wool-osmium tetroxide(wool-OsO4) complex was prepared by a very simple method. This complex was found to be able to catalyze the asymmetric dihydroxylation of allylamine to get (R)-(+)-3-amino-l, 2-propanediol. The experimental results showed that OsO4 content in the complex, reaction time, allylamine/OsO4 molar ratio all have great effects on the chemical and optical yields of product. Additionally, wool-OsO4 complex catalyst could be reused without remarkable change in optical catalytic activity.
