Fine nickel ferrite precursors NiFe2（C204）3·6H2O were obtained via co-precipitation method with low grade nickel matte as the raw material. Thermodynamic analysis of NiClz-FeC12-（NH4）2C204-H20 system for prec...Fine nickel ferrite precursors NiFe2（C204）3·6H2O were obtained via co-precipitation method with low grade nickel matte as the raw material. Thermodynamic analysis of NiClz-FeC12-（NH4）2C204-H20 system for precipitation identified that the theoretical optimum co-precipitation pH value is 2, and C2O2 has strong complexation with Ni2＋ and Fe2＋ ions. Based on these theoretical considerations, the effects of parameters on the precipitation rates and precursors size were investigated systematically. The results show that the optimum co-precipitation conditions are pH=2, temperature 45 ℃, 1.2 times theoretical amount of （NH4）2C204 dosage and 3% PEG400 addition. Under these conditions, the precipitation rates of Ni2＋ and Fe2＋ are both over 99.8%, with the precursors size of 1-2 urn. Furthermore, X-ray diffraction （XRD） and thermogravimetry-differential thermal analysis （TG-DTA） demonstrate that the precursors are single-phase solid solution, wherein the nickel/iron atoms are replaced by the iron/nickel atoms reciprocally.展开更多
A new hydrometallurgical route for separation and recovery of Cu from Cu-As-bearing copper electrorefining black slime was developed. The proposed process comprised oxidation acid leaching of Cu-As-bearing slime and s...A new hydrometallurgical route for separation and recovery of Cu from Cu-As-bearing copper electrorefining black slime was developed. The proposed process comprised oxidation acid leaching of Cu-As-bearing slime and selective sulfide precipitation of Cu from the leachate. The effects of various process parameters on the leaching and precipitation of Cu and As were investigated. At the first stage, Cu extraction of 95.2% and As extraction of 97.6% were obtained at 80 ℃ after 4 h with initial H2 SO4 concentration of 1.0 mol/L and liquid-to-solid ratio of 10 mL/g. In addition, the leaching kinetics of Cu and As was successfully reproduced by the Avrami model, and the apparent activation energies were found to be 33.6 and 35.1 kJ/mol for the Cu and As leaching reaction, respectively, suggesting a combination of chemical reaction and diffusion control. During the selective sulfide precipitation, about 99.4% Cu was recovered as CuS, while only 0.1% As was precipitated under the optimal conditions using sulfide-to-copper ratio of 2.4:1, time of 1.5 h and temperature of 25 ℃.展开更多
A strain HB-03 to produce alkaline extracellular lipase was isolated from oil-rich soil samples and identified as Aspergillus awamori. The growth conditions and nutritional factors for lipase production by strain HB-0...A strain HB-03 to produce alkaline extracellular lipase was isolated from oil-rich soil samples and identified as Aspergillus awamori. The growth conditions and nutritional factors for lipase production by strain HB-03 were optimized, and the maximum lipase production of （45.9±2.3） U/mL was obtained at 30 ℃ and pH 7.0 after 36 h using olive oil （1%） and sucrose （0.5%） as carbon sources and combination of peptone （2%）, yeast extract （0.5%） and ammonium sulfate （0.1%） as nitrogen sources. The lipase was purified to homogeneity with 10.6-fold, 18.84% yield and a specific activity of 1 862.2 U/mg using ammonium sulfate precipitation followed by SephadexG-75 gel filtration chromatography. The purified lipase with molecular mass of 68 ku was estimated by SDS-PAGE. The optimum pH and temperature for the purified lipase were found to be 8.5 and 40 ℃, respectively. The lipase kept more than 80% of activity in pH 7.0-10.0 and temperatures up to 45 ℃. The metal ions of Mn2＋, Ba2＋ significantly enhanced the lipase activity, whereas Cu2＋, Fe3＋ and Mg2＋ strongly reduced the lipase activity. The Km and Vmax values of the purified enzyme for p-nitrophenyl palmitate were 0.13 mrnol/L and 60.6 mmol/（L.min）, respectively. The results show that this novel lipase has potential industrial applications.展开更多
Biochemical changes of natural actomyosin from fresh pale, soft, exudative (PSE) and normal pork were studied,and the effects of different storage temperatures and different incubation temperature and times on sample ...Biochemical changes of natural actomyosin from fresh pale, soft, exudative (PSE) and normal pork were studied,and the effects of different storage temperatures and different incubation temperature and times on sample superprecipitation,total sulfhydryl (-SH) content, and ATP (adenosine triphosphate) sensitivity were investigated. The results demonstrated that ATPase activity and thermal stability of PSE actomyosin were lower than those of normal pork; and that PSE actomyosin had higher -SH content than that of normal pork at all incubation temperatures and times tested.展开更多
LiFePO4 cathode material is synthesized by a simple solid-state reaction method with FePO42H20 as iron source and citric acid as reductive agent and carbon source. This study examines the effects of different oxidatio...LiFePO4 cathode material is synthesized by a simple solid-state reaction method with FePO42H20 as iron source and citric acid as reductive agent and carbon source. This study examines the effects of different oxidation routes to prepare FePO4＂2H20 on the electrochemical performance of as-synthesized LiFePO4. Iron phosphate was prepared by two routes from FeSO4＇7H20. One is the formation of Fe3（PO4）2 precipitate in the first step and subsequent oxidation to FePO4 precipitate. The other is the oxidation of ferrous to ferric ion firstly, and then to form FePO4 precipitate directly. The results indicate that substantial differences in the structure and electrochemical properties of LiFePO4 depend on the behavior of FePO4. Iron phosphate obtained through one step precipitation has a smaller particle size and more uniform particle distribution, which is demonstrated to be more applicable as the iron source to synthesize LiFePO4/C. As-prepared LiFePO4/C shows an excellent rate capability and cycle performance. The initial discharge capacities of 160.6 mAh/g and 107 mAh/g are achieved at 0.1 C and 10 C, respectively. The good capacity retention of 97% after 300 cycles is maintained at the rate of 5 C.展开更多
The BINOL-amino alcohol enantiomeric pair （S）-I and （R）-I are discovered to conduct both enantioselective and diastereose- lective fluorescent discrimination of the four stereoisomers of threonine derivatives. Thi...The BINOL-amino alcohol enantiomeric pair （S）-I and （R）-I are discovered to conduct both enantioselective and diastereose- lective fluorescent discrimination of the four stereoisomers of threonine derivatives. This study utilizes different fluorescence responses of one sensor at two emission wavelengths toward the stereoisomeric substrates which expands the capability of the sensor in chiral recognition. In addition, the sensor pair also allows visual recognition of the N-protected L-allo-threonine and D-allo-threonine by enantioselective precipitation.展开更多
基金Project(2012BAB10B04) supported by National Key Technology R&D Program of ChinaProject supported by Hunan Provincial Innovation Foundation for Postgraduate,China
文摘Fine nickel ferrite precursors NiFe2（C204）3·6H2O were obtained via co-precipitation method with low grade nickel matte as the raw material. Thermodynamic analysis of NiClz-FeC12-（NH4）2C204-H20 system for precipitation identified that the theoretical optimum co-precipitation pH value is 2, and C2O2 has strong complexation with Ni2＋ and Fe2＋ ions. Based on these theoretical considerations, the effects of parameters on the precipitation rates and precursors size were investigated systematically. The results show that the optimum co-precipitation conditions are pH=2, temperature 45 ℃, 1.2 times theoretical amount of （NH4）2C204 dosage and 3% PEG400 addition. Under these conditions, the precipitation rates of Ni2＋ and Fe2＋ are both over 99.8%, with the precursors size of 1-2 urn. Furthermore, X-ray diffraction （XRD） and thermogravimetry-differential thermal analysis （TG-DTA） demonstrate that the precursors are single-phase solid solution, wherein the nickel/iron atoms are replaced by the iron/nickel atoms reciprocally.
基金financial supports from the National Natural Science Foundation of China (51634010,51904354)the National Science Fund for Distinguished Young Scholars of China (51825403)+1 种基金the National Key R&D Program of China (2018YFC1900306,2019YFC1907405)Key Research and Development Program of Hunan Province,China (2019SK2291)。
文摘A new hydrometallurgical route for separation and recovery of Cu from Cu-As-bearing copper electrorefining black slime was developed. The proposed process comprised oxidation acid leaching of Cu-As-bearing slime and selective sulfide precipitation of Cu from the leachate. The effects of various process parameters on the leaching and precipitation of Cu and As were investigated. At the first stage, Cu extraction of 95.2% and As extraction of 97.6% were obtained at 80 ℃ after 4 h with initial H2 SO4 concentration of 1.0 mol/L and liquid-to-solid ratio of 10 mL/g. In addition, the leaching kinetics of Cu and As was successfully reproduced by the Avrami model, and the apparent activation energies were found to be 33.6 and 35.1 kJ/mol for the Cu and As leaching reaction, respectively, suggesting a combination of chemical reaction and diffusion control. During the selective sulfide precipitation, about 99.4% Cu was recovered as CuS, while only 0.1% As was precipitated under the optimal conditions using sulfide-to-copper ratio of 2.4:1, time of 1.5 h and temperature of 25 ℃.
文摘A strain HB-03 to produce alkaline extracellular lipase was isolated from oil-rich soil samples and identified as Aspergillus awamori. The growth conditions and nutritional factors for lipase production by strain HB-03 were optimized, and the maximum lipase production of （45.9±2.3） U/mL was obtained at 30 ℃ and pH 7.0 after 36 h using olive oil （1%） and sucrose （0.5%） as carbon sources and combination of peptone （2%）, yeast extract （0.5%） and ammonium sulfate （0.1%） as nitrogen sources. The lipase was purified to homogeneity with 10.6-fold, 18.84% yield and a specific activity of 1 862.2 U/mg using ammonium sulfate precipitation followed by SephadexG-75 gel filtration chromatography. The purified lipase with molecular mass of 68 ku was estimated by SDS-PAGE. The optimum pH and temperature for the purified lipase were found to be 8.5 and 40 ℃, respectively. The lipase kept more than 80% of activity in pH 7.0-10.0 and temperatures up to 45 ℃. The metal ions of Mn2＋, Ba2＋ significantly enhanced the lipase activity, whereas Cu2＋, Fe3＋ and Mg2＋ strongly reduced the lipase activity. The Km and Vmax values of the purified enzyme for p-nitrophenyl palmitate were 0.13 mrnol/L and 60.6 mmol/（L.min）, respectively. The results show that this novel lipase has potential industrial applications.
基金Project (No. 200019) supported by the Natural Science Foundation of Zhejiang Province,China
文摘Biochemical changes of natural actomyosin from fresh pale, soft, exudative (PSE) and normal pork were studied,and the effects of different storage temperatures and different incubation temperature and times on sample superprecipitation,total sulfhydryl (-SH) content, and ATP (adenosine triphosphate) sensitivity were investigated. The results demonstrated that ATPase activity and thermal stability of PSE actomyosin were lower than those of normal pork; and that PSE actomyosin had higher -SH content than that of normal pork at all incubation temperatures and times tested.
基金supported by a project issued by the National Key Technologies R&D Program of China (2009BAG19B00)National High Technology Research and Development Program of China (SS2012AA110301)
文摘LiFePO4 cathode material is synthesized by a simple solid-state reaction method with FePO42H20 as iron source and citric acid as reductive agent and carbon source. This study examines the effects of different oxidation routes to prepare FePO4＂2H20 on the electrochemical performance of as-synthesized LiFePO4. Iron phosphate was prepared by two routes from FeSO4＇7H20. One is the formation of Fe3（PO4）2 precipitate in the first step and subsequent oxidation to FePO4 precipitate. The other is the oxidation of ferrous to ferric ion firstly, and then to form FePO4 precipitate directly. The results indicate that substantial differences in the structure and electrochemical properties of LiFePO4 depend on the behavior of FePO4. Iron phosphate obtained through one step precipitation has a smaller particle size and more uniform particle distribution, which is demonstrated to be more applicable as the iron source to synthesize LiFePO4/C. As-prepared LiFePO4/C shows an excellent rate capability and cycle performance. The initial discharge capacities of 160.6 mAh/g and 107 mAh/g are achieved at 0.1 C and 10 C, respectively. The good capacity retention of 97% after 300 cycles is maintained at the rate of 5 C.
文摘The BINOL-amino alcohol enantiomeric pair （S）-I and （R）-I are discovered to conduct both enantioselective and diastereose- lective fluorescent discrimination of the four stereoisomers of threonine derivatives. This study utilizes different fluorescence responses of one sensor at two emission wavelengths toward the stereoisomeric substrates which expands the capability of the sensor in chiral recognition. In addition, the sensor pair also allows visual recognition of the N-protected L-allo-threonine and D-allo-threonine by enantioselective precipitation.
