[Objectives]To explore the extraction conditions of essential oil from eucalyptus leaves.[Methods]The essential oil of eucalyptus leaves was extracted by steam distillation,and the yields of essential oil from eucalyp...[Objectives]To explore the extraction conditions of essential oil from eucalyptus leaves.[Methods]The essential oil of eucalyptus leaves was extracted by steam distillation,and the yields of essential oil from eucalyptus leaves under different extraction times,soaking times and different solid-liquid ratios were analyzed through orthogonal test with three factors and three variables.[Results]The effects of various factors on extraction results were:distillation time>solid-liquid ratio>soaking time.When the extraction time and soaking time were 1.5 and 2 h,and the solid-liquid ratio of eucalyptus leaves to distilled water was 1:10,the yield of essential oil was the highest(0.8%).The yield of essential oil increased with the increase of extraction and soaking time,but when reaching the optimal value,the yield decreased with the extension of time.Increasing the solid-liquid ratio can improve the yield of essential oil,but beyond a certain value the yield increased gradually while the cost performance decreased.[Conclusions]The results will provide some reference for the recovery and utilization of eucalyptus leaves.展开更多
Potassium bismuth titanate nanosized powders were prepared by the hydrothermal method using Ti(C_4H_9O)_4 and Bi(NO_3)_3·5H_2O as raw materials in alkaline solution.The phase composition,particle size and morphol...Potassium bismuth titanate nanosized powders were prepared by the hydrothermal method using Ti(C_4H_9O)_4 and Bi(NO_3)_3·5H_2O as raw materials in alkaline solution.The phase composition,particle size and morphology of the powders were studied by XRD and TEM analysis.The results showed that the powders were well crystallized and dispersed.The crystal phase of the powders was K_(0.5)Bi_(0.5)TiO_3 with the grain size of about 50 nm～100 nm.Hydrothermal temperature and alkaline concentrations had great effects on the phase composition and morphology of the resultant powders.Pure K_(0.5)Bi_(0.5)TiO_3 powders could be synthesized at 170℃～180℃with KOH concentration of 8 mol/L～12 mol/L.展开更多
The exergy losses and thermodynamic efficiency of MSF plant with brine recirculation are discussed bymeans of temperature difference functions proposed by the auther.In a MSF plant,the irreversible losses are found ma...The exergy losses and thermodynamic efficiency of MSF plant with brine recirculation are discussed bymeans of temperature difference functions proposed by the auther.In a MSF plant,the irreversible losses are found mainly in irreversible heat-transfer and flash evaporationprocesses.However,the basic variables are the temperature drop from stage to stage and the temperaturedifferences between flashed vapor and cooling water.In this paper,the flash temperature difference func-tion,the heat transfer temperature difference function and the total temperature difference function are sug-gested.The proposed temperature difference functions of MSF plant provide a convenient tool to analyse theirreversible behavior and evaluate the exergetic efficiency of this system,because without such improvement thecalculation of the exergetic efficiency of a MSF plant according to the classical formula will be not onlyinconvenient but also insignificant.As a result of present analysis,the reasonable parameters based on theenergy consumption are easily chosen.The above-mentioned principles are confirmed by commercial plants and a pilot plant in Tianjin.展开更多
[Objectives] To study the optimal extraction process for polysaccharides of Urtica fissa E. Pritz. [Methods] Leaves of wild U. fissa E. Pritz. collected in Nyingchi of Tibet were used as raw materials. Water extractio...[Objectives] To study the optimal extraction process for polysaccharides of Urtica fissa E. Pritz. [Methods] Leaves of wild U. fissa E. Pritz. collected in Nyingchi of Tibet were used as raw materials. Water extraction method was used to extract polysaccharides from U. fissa E. Pritz. Besides,comparison was made for the effects of extraction time,extraction temperature and solid-to-liquid ratio on the yield rate of polysaccharides from U. fissa E. Pritz. In addition,using the extraction time,extraction temperature and solid-to-liquid ratio as factors,L9( 33) orthogonal experiment was carried out to determine the optimal process parameters for water extraction of polysaccharides from U. fissa E. Pritz.[Results] The optimal process parameters: hot water extraction time was 4 h,the extraction temperature was 90℃,and the mass ratio of water to leaves of U. fissa E. Pritz. was 1∶ 25. Under such extraction conditions,the yield rate of polysaccharides from U. fissa E. Pritz.was up to 11. 611%. [Conclusions]This experiment is expected to provide certain reference for reasonable development and utilization of wild U. fissa E. Pritz. resources in Tibet.展开更多
The effect of the deformation condition on the axial compressive precision forming process of tube with curling die was investigated by using a rigid-plastic FEM. The results show that the forming accuracy depends mai...The effect of the deformation condition on the axial compressive precision forming process of tube with curling die was investigated by using a rigid-plastic FEM. The results show that the forming accuracy depends mainly on geometric condition rp/d0, little on tube material properties and friction condition; the relative gap △/2rp of double-walled tubes obtained decreases with Increasing rp/d0, and there is a parameter k for a given to/do or rp/t0, when rp/d0 >k, △/2rp< 1, otherwise △/2rp>1.展开更多
The gold deposits in the Jiaodong Peninsula constitute the largest gold mineralized province in China.The mineralization shows common characteristics in their tectonic setting,ore-forming fluid and metallogenic system...The gold deposits in the Jiaodong Peninsula constitute the largest gold mineralized province in China.The mineralization shows common characteristics in their tectonic setting,ore-forming fluid and metallogenic system.Sulfidation and fluid immiscibility are two important mechanisms controlling gold precipitation,both of which consume sulfur in the oreforming fluids.The escape of H2S from the main ore-forming fluids and the decrease of total sulfur concentration not only lead to the efficient precipitation of gold,but also result in the crystallization of reducing minerals such as pyrrhotite and oxidizing minerals such as magnetite.Quartz solubility shows strong dependence on temperature,pressure,and CO2 content.The dependence of quartz solubility on pressure is weak at low temperatures,and progressively stronger at higher temperatures.Similarly,the temperature dependence of quartz solubility is relatively low at low pressures,but becomes gradually stronger at high pressures.The results of solubility modeling can constrain the dissolution and reprecipitation behavior of quartz in the oreforming veins and the formation mechanism of different types of quartz veins.The multi-stage mineralization fluid activity resulted in the complex dissolution structure of quartz in the Jiaodong gold veins.Pyrite in the main metallogenic period in the Jiaodong gold deposits shows complex microstructure characteristics at single crystal scale.The trace elements(mainly the coupling of As-and Au-rich belt)and sulfur isotope composition also display a certain regularity.The As-rich fluids might have formed by the initial pulse of ore-forming fluids through As-rich metasedimentary strata,while the As-Au oscillation zone at the margin of pyrite grains is related to the pressure fluctuation caused by fault activity and the local phase separation of fluids.There is a temporal and spatial evolution of gold fineness in the Jiaodong gold deposits.Water/rock reaction(sulfidation)was the main ore-forming mechanism of early gold mineralization,forming relatively high fineness gold,while significant pressure drop in the shallow part accompanied by fluid phase separation promoted the late gold mineralization,forming low fineness gold.Under cratonic destruction setting,dehydration of the amphibolite and granulite facies metamorphic lower-crust resulted in the formation of Au-CO2-rich ore-forming fluids,which rose along the deep fault and secondary structure,and formed the largescale fault-controlled gold deposits in Jiaodong.展开更多
The microstructure and corrosion resistance of Mg-0.5 Zn-0.2 Ca-0.2 Ce alloy with different processing conditions were investigated.The composition was detected by X-ray fluorescence(XRF),and the microstructure was an...The microstructure and corrosion resistance of Mg-0.5 Zn-0.2 Ca-0.2 Ce alloy with different processing conditions were investigated.The composition was detected by X-ray fluorescence(XRF),and the microstructure was analyzed by optical microscopy(OM)and scanning electron microscope(SEM)equipped with energy-dispersive spectroscopy(EDS).The corrosion behavior was investigated by hydrogen evolution tests,weight loss tests and electrochemical measurements.The Mg-0.5 Zn-0.2 Ca-0.2 Ce alloy has much better corrosion resistance compared with the commercial AZ31 sheet,which can be attributed to its dispersive second phases and protective corrosion products film on the alloy surface.Moreover,the as-rolled Mg-0.5 Zn-0.2 Ca-0.2 Ce alloy shows much better corrosion resistance compared with the as-extruded Mg-0.5 Zn-0.2 Ca-0.2 Ce alloy.This can be due to three aspects:The as-rolled alloy has smaller grain size;the as-rolled alloy has lower(1010)/(1120)texture intensity;the residual stress of the as-rolled alloy is eliminated during the annealing process,but large residual stress exists in the asextruded alloy produced by the extrusion process.展开更多
Microwave technology is fit for the processing of berry products,but it may affect nutrition components of berry fruit.To improve the nutritional value of the berry products,the influences of microwave vacuum puffing ...Microwave technology is fit for the processing of berry products,but it may affect nutrition components of berry fruit.To improve the nutritional value of the berry products,the influences of microwave vacuum puffing conditions on the anthocyanin content of raspberry snack were investigated using central composite experiments.Results indicated that vacuum pressure had the most significant effect on the anthocyanins of berry snack,followed by the puffing time,microwave power,and initial moisture content.The interaction between microwave power and puffing time on the anthocyanins was extremely significant.Under microwave power of 2.68 kW and the puffing time of 81.00 s,the anthocyanin content of raspberry snack was retained at high level.The results can provide some technological basis for the berry fruit products processed with high quality.展开更多
基金Supported by Doctoral Start-up Fund of Guangxi Minzu Normal University(2021 BS003).
文摘[Objectives]To explore the extraction conditions of essential oil from eucalyptus leaves.[Methods]The essential oil of eucalyptus leaves was extracted by steam distillation,and the yields of essential oil from eucalyptus leaves under different extraction times,soaking times and different solid-liquid ratios were analyzed through orthogonal test with three factors and three variables.[Results]The effects of various factors on extraction results were:distillation time>solid-liquid ratio>soaking time.When the extraction time and soaking time were 1.5 and 2 h,and the solid-liquid ratio of eucalyptus leaves to distilled water was 1:10,the yield of essential oil was the highest(0.8%).The yield of essential oil increased with the increase of extraction and soaking time,but when reaching the optimal value,the yield decreased with the extension of time.Increasing the solid-liquid ratio can improve the yield of essential oil,but beyond a certain value the yield increased gradually while the cost performance decreased.[Conclusions]The results will provide some reference for the recovery and utilization of eucalyptus leaves.
文摘Potassium bismuth titanate nanosized powders were prepared by the hydrothermal method using Ti(C_4H_9O)_4 and Bi(NO_3)_3·5H_2O as raw materials in alkaline solution.The phase composition,particle size and morphology of the powders were studied by XRD and TEM analysis.The results showed that the powders were well crystallized and dispersed.The crystal phase of the powders was K_(0.5)Bi_(0.5)TiO_3 with the grain size of about 50 nm～100 nm.Hydrothermal temperature and alkaline concentrations had great effects on the phase composition and morphology of the resultant powders.Pure K_(0.5)Bi_(0.5)TiO_3 powders could be synthesized at 170℃～180℃with KOH concentration of 8 mol/L～12 mol/L.
文摘The exergy losses and thermodynamic efficiency of MSF plant with brine recirculation are discussed bymeans of temperature difference functions proposed by the auther.In a MSF plant,the irreversible losses are found mainly in irreversible heat-transfer and flash evaporationprocesses.However,the basic variables are the temperature drop from stage to stage and the temperaturedifferences between flashed vapor and cooling water.In this paper,the flash temperature difference func-tion,the heat transfer temperature difference function and the total temperature difference function are sug-gested.The proposed temperature difference functions of MSF plant provide a convenient tool to analyse theirreversible behavior and evaluate the exergetic efficiency of this system,because without such improvement thecalculation of the exergetic efficiency of a MSF plant according to the classical formula will be not onlyinconvenient but also insignificant.As a result of present analysis,the reasonable parameters based on theenergy consumption are easily chosen.The above-mentioned principles are confirmed by commercial plants and a pilot plant in Tianjin.
基金Supported by Project of Natural Science Foundation of Tibet Autonomous Region(2016ZR-15-31)
文摘[Objectives] To study the optimal extraction process for polysaccharides of Urtica fissa E. Pritz. [Methods] Leaves of wild U. fissa E. Pritz. collected in Nyingchi of Tibet were used as raw materials. Water extraction method was used to extract polysaccharides from U. fissa E. Pritz. Besides,comparison was made for the effects of extraction time,extraction temperature and solid-to-liquid ratio on the yield rate of polysaccharides from U. fissa E. Pritz. In addition,using the extraction time,extraction temperature and solid-to-liquid ratio as factors,L9( 33) orthogonal experiment was carried out to determine the optimal process parameters for water extraction of polysaccharides from U. fissa E. Pritz.[Results] The optimal process parameters: hot water extraction time was 4 h,the extraction temperature was 90℃,and the mass ratio of water to leaves of U. fissa E. Pritz. was 1∶ 25. Under such extraction conditions,the yield rate of polysaccharides from U. fissa E. Pritz.was up to 11. 611%. [Conclusions]This experiment is expected to provide certain reference for reasonable development and utilization of wild U. fissa E. Pritz. resources in Tibet.
基金The authors would like to thank NSFC for support toenable the performing of this research (No. 59775055).
文摘The effect of the deformation condition on the axial compressive precision forming process of tube with curling die was investigated by using a rigid-plastic FEM. The results show that the forming accuracy depends mainly on geometric condition rp/d0, little on tube material properties and friction condition; the relative gap △/2rp of double-walled tubes obtained decreases with Increasing rp/d0, and there is a parameter k for a given to/do or rp/t0, when rp/d0 >k, △/2rp< 1, otherwise △/2rp>1.
基金supported by the National Key Research and Development Program(Grant No.2016YFC0600105)the National Natural Science Foundation of China(Grant Nos.41672094,41772080)。
文摘The gold deposits in the Jiaodong Peninsula constitute the largest gold mineralized province in China.The mineralization shows common characteristics in their tectonic setting,ore-forming fluid and metallogenic system.Sulfidation and fluid immiscibility are two important mechanisms controlling gold precipitation,both of which consume sulfur in the oreforming fluids.The escape of H2S from the main ore-forming fluids and the decrease of total sulfur concentration not only lead to the efficient precipitation of gold,but also result in the crystallization of reducing minerals such as pyrrhotite and oxidizing minerals such as magnetite.Quartz solubility shows strong dependence on temperature,pressure,and CO2 content.The dependence of quartz solubility on pressure is weak at low temperatures,and progressively stronger at higher temperatures.Similarly,the temperature dependence of quartz solubility is relatively low at low pressures,but becomes gradually stronger at high pressures.The results of solubility modeling can constrain the dissolution and reprecipitation behavior of quartz in the oreforming veins and the formation mechanism of different types of quartz veins.The multi-stage mineralization fluid activity resulted in the complex dissolution structure of quartz in the Jiaodong gold veins.Pyrite in the main metallogenic period in the Jiaodong gold deposits shows complex microstructure characteristics at single crystal scale.The trace elements(mainly the coupling of As-and Au-rich belt)and sulfur isotope composition also display a certain regularity.The As-rich fluids might have formed by the initial pulse of ore-forming fluids through As-rich metasedimentary strata,while the As-Au oscillation zone at the margin of pyrite grains is related to the pressure fluctuation caused by fault activity and the local phase separation of fluids.There is a temporal and spatial evolution of gold fineness in the Jiaodong gold deposits.Water/rock reaction(sulfidation)was the main ore-forming mechanism of early gold mineralization,forming relatively high fineness gold,while significant pressure drop in the shallow part accompanied by fluid phase separation promoted the late gold mineralization,forming low fineness gold.Under cratonic destruction setting,dehydration of the amphibolite and granulite facies metamorphic lower-crust resulted in the formation of Au-CO2-rich ore-forming fluids,which rose along the deep fault and secondary structure,and formed the largescale fault-controlled gold deposits in Jiaodong.
基金the National Natural Science Foundation of China(Nos.51671041,51701029 and 51531002)the National Key Research and Development Program of China(No.2016YFB0301100)+2 种基金the Fundamental Research Funds for the Central Universities(No.106112016CDJXZ138811)China Postdoctoral Science Foundation Funded Project(Nos.2017M620410 and 2018T110942)the Chongqing Postdoctoral Scientific Research Foundation(No.Xm2017010)。
文摘The microstructure and corrosion resistance of Mg-0.5 Zn-0.2 Ca-0.2 Ce alloy with different processing conditions were investigated.The composition was detected by X-ray fluorescence(XRF),and the microstructure was analyzed by optical microscopy(OM)and scanning electron microscope(SEM)equipped with energy-dispersive spectroscopy(EDS).The corrosion behavior was investigated by hydrogen evolution tests,weight loss tests and electrochemical measurements.The Mg-0.5 Zn-0.2 Ca-0.2 Ce alloy has much better corrosion resistance compared with the commercial AZ31 sheet,which can be attributed to its dispersive second phases and protective corrosion products film on the alloy surface.Moreover,the as-rolled Mg-0.5 Zn-0.2 Ca-0.2 Ce alloy shows much better corrosion resistance compared with the as-extruded Mg-0.5 Zn-0.2 Ca-0.2 Ce alloy.This can be due to three aspects:The as-rolled alloy has smaller grain size;the as-rolled alloy has lower(1010)/(1120)texture intensity;the residual stress of the as-rolled alloy is eliminated during the annealing process,but large residual stress exists in the asextruded alloy produced by the extrusion process.
基金The authors thank the financial support by the National Natural Science Foundation of China(No.31071579&31271911)the Key Program of the Natural Science Foundation of Heilongjiang Province of China(No.ZD201013)Key Project of Education Department of Heilongjiang Province of China(No.12521z003)for this research project.
文摘Microwave technology is fit for the processing of berry products,but it may affect nutrition components of berry fruit.To improve the nutritional value of the berry products,the influences of microwave vacuum puffing conditions on the anthocyanin content of raspberry snack were investigated using central composite experiments.Results indicated that vacuum pressure had the most significant effect on the anthocyanins of berry snack,followed by the puffing time,microwave power,and initial moisture content.The interaction between microwave power and puffing time on the anthocyanins was extremely significant.Under microwave power of 2.68 kW and the puffing time of 81.00 s,the anthocyanin content of raspberry snack was retained at high level.The results can provide some technological basis for the berry fruit products processed with high quality.
