The influence of chemical composition on corrosion resistance of AZ91D magnesium alloys ingots has been investigated. Mass loss method was applied to evaluate the corrosion resistance of AZ91D alloys and the data were...The influence of chemical composition on corrosion resistance of AZ91D magnesium alloys ingots has been investigated. Mass loss method was applied to evaluate the corrosion resistance of AZ91D alloys and the data were analyzed by multiple regression. The results show that the corrosion resistance of this alloy can be improved by increasing Al, Zn and Mn in a certain degree, and will drop with increasing Si and heavy metals (Fe, Cu, Ni). It is found that ingots received from company F should be listed into unusable materials in terms of the corrosion resistance, while among the five suppliers, the only local company E supplied excellent AZ91D magnesium alloy ingots with the best corrosion resistance.展开更多
Source apportionment of particulate matters with aerodynamic diameter less than 10 μm （PM10） was conducted in the suburban area of Changsha, China. PM10 samples for 24 h collected with TEOM 1400a and ACCU system in...Source apportionment of particulate matters with aerodynamic diameter less than 10 μm （PM10） was conducted in the suburban area of Changsha, China. PM10 samples for 24 h collected with TEOM 1400a and ACCU system in July and October 2008 were chemically analyzed by the wavelength dispersive X-ray fluorescence （WD-XRF）. Source appointment was implemented by the principal component analysis/absolute principal component analysis （PCA/APCA） to identify the possible sources and to quantify the contributions of the sources to PM10. Results show that as the PM10 concentration is increased from （85.6±43.7） μg/m3 in July 2008 to （107.6±35.7） μg/m^3 in October 2008, the concentrations of the anthropogenic elements （P, S, C1, K, Mn, Ni, Cu, Zn, and Pb） are basically increased but concentrations of the natural elements （Na, Mg, Al, Si, Ca, Ti, and Fe） are essentially decreased. Six main sources of PM10 are identified in the suburban of Changsha, China： soil dust, secondary aerosols, domestic oil combustion, waste incineration, traffic emission, and industrial emission contribute 57.7%, 24.0%, 9.8%, 5.0%, 2.0%, and 1.5%, respectively. Soil dust and secondary aerosols are the two major sources of particulate air pollution in suburban area of Changsha, China, so effective measures should be taken to control these two particulate pollutants.展开更多
The influence of chemical composition and cold deformation on aging precipitation behavior of 18Cr-16Mn-2Mo-I.IN （HNS-A）, 18Cr-16Mn-I.3N （HNS-B）, 18Cr-18Mn-2Mo-0.96N （HNS-C） and 18Cr-18Mn-2Mo-0.77N （I-INS-D） h...The influence of chemical composition and cold deformation on aging precipitation behavior of 18Cr-16Mn-2Mo-I.IN （HNS-A）, 18Cr-16Mn-I.3N （HNS-B）, 18Cr-18Mn-2Mo-0.96N （HNS-C） and 18Cr-18Mn-2Mo-0.77N （I-INS-D） high nitrogen austenitic stainless steels was investigated. The results show that the ＂nose＂ temperatures and incubation periods of the initial time-temperature-precipitation （TTP） curves of aged HNSs are found to be 850 ℃, 60 s; 850 ℃, 45 s; 850 ℃, 60 s and 900 ℃, 90 s, respectively. Based on the analysis of SAD patterns, the coarse cellular Cr2N precipitate which presents a lamellar structure has a hexagonal structure of a=0.478 nm and c=0.444 nm. The Z phase corresponding to a composition of Fe36Cr^2Mo10, is determined to be a body-centered cubic structure ofa=0.892 nm. The precipitating sensitivity presents no more difference with the nitrogen content increasing from 0.77% to 0.96%, but exhibits so obviously that the cellular precipitates nearly overspread the whole field. The addition of Mo element can restrain the TTP curves moving left and down, which means decreasing the sensitivity of aging precipitation. With increasing the cold deformation, the sensitivity of precipitation increases obviously.展开更多
Two experiments were conducted to study the effects of variety and maturity stage on chemical composition and in vitro dry matter degradability of oat and barley forages. In exp1, four oat varieties and one barley var...Two experiments were conducted to study the effects of variety and maturity stage on chemical composition and in vitro dry matter degradability of oat and barley forages. In exp1, four oat varieties and one barley variety were harvested at three maturity stages: stage 1, Two weeks before stage 2; stage 2, Mid-dough for oat and early-dough for barley; stage 3, One week after stage 2. All samples were analyzed for DM, CP, ether extract, ash, ADF(acid detergent fiber), NDF(neutral detergent fiber), ADL(acid detergent lignin), NDICP(neutral detergent insoluble crude protein) and IVDMD(In vitro dry matter digestibility). There was no difference in chemical components and IVDMD among oat variety. But maturity stage had a profound influence on some nutrient contents and IVDMD. With maturity advancing, CP decreased from15.5% to 11.03% and from 14.7% to 10.9% at stage 1 and stage 2 for oat and for barley, respectively, and IVDMD decreased slowly from 72.0% to 64.9% and from 73.5% to 68.8% for oat and for barley, respectively. For fiber fractions, NDF declined before stage 2 and then level off after stage 2, while ADF changed little throughout maturation. The ADL trended to increase with increased maturity. The results from the present experiment revealed that Bailor has relatively greater IVDMD value and kept lower ADL content than any other cultivars. The observed variation in chemical composition and ruminal digestibility among various oat cultivars would allow breeders choose suitable oat forages for cattle diet. In experiment. 2, the DaisyⅡ incubator was used to compare IVDMD values of forages of seven oat cultivars using rumen fluid or faecal liquor as the inoculum source. There was a strong linear relationship between the two estimates (R 2 = 0.809; P < 0.001), which indicated that fecal liquor method has the potential to be used instead of rumen fluid for estimation of in vitro digestibility of forage. It is suggested the method for determination of IVDMD using faecal liquor was appropriate for batch operation with precision and efficiency.展开更多
This study was to investigate the effects of three exogenous substances on chemical constituents of Isatis indigotica leavesand their efficacy in alleviating drought stress, and explore the methods of applying exogeno...This study was to investigate the effects of three exogenous substances on chemical constituents of Isatis indigotica leavesand their efficacy in alleviating drought stress, and explore the methods of applying exogenous substances to efficient cultivationof Isatis indigotica. Polyethylene glycol (PEG) was used to simulate drought stress to deal with seeds of Isatis indigotica at thegermination stage (concentration: 0, 10%, 15%, and 20%). Simultaneous operation of exogenous growth regulators [microbialinoculum (MI), γ-aminobutyric acid (GABA) and salicylic acid (SA)] and PEG were implemented in seeds of Isatis indigotica.The effects of drought stress and the mitigation of exogenous substances were observed by statistics of seed germination potential,germination rate, hypocotyl length, and radicle length of each treatment. The effects of exogenous substances on the content ofalkaloids, crude protein and free amino acids in the leaves of Isatis indigotica grown in a greenhouse were determined after sprayingexogenous substances on the plants. The differences of germination potential, germination rate, hypocotyl length, and radicle lengthamong 15% PEG stress treatment, 10% PEG stress treatment and the control were significant (P<0.05). According to the predesignedgermination standard, the seeds did not germinate under 20% PEG stress treatment. When the PEG concentration was 15%, the resultsof seed germination potential and germination rate after adding MI were significantly different from those under stress alone (P<0.05).When exposed to 10% PEG stress, the supplementation of GABA led to a notable increase in radicle length of Isatis indigotica seeds,showing significant differences compared to other three treatments. The application of MI and GABA under 15% PEG stress resultedin a significant increase in the radicle and hypocotyl length of Isatis indigotica seeds compared to other two treatments. The contentof the total alkaloids in leaves of Isatis indigotica was significantly increased after spraying GABA. Meanwhile, the contents of crudeprotein and the total free amino acids were kept constant after spraying exogenous substances. Application of MI and GABA couldalleviate drought stress of Isatis indigotica. The content of the total alkaloids in leaves of Isatis indigotica could significantly increaseafter spraying GABA.展开更多
This study was undertaken to optimize the solvent-free microwave extraction conditions and DPPH radicalscavenging activity of essential oil from Schisandra chinesis fruits.The uniform design method was employed for pr...This study was undertaken to optimize the solvent-free microwave extraction conditions and DPPH radicalscavenging activity of essential oil from Schisandra chinesis fruits.The uniform design method was employed for process optimization.The optimal extraction conditions were determined as follows:extraction time,50 rain;microwave power,800 W;and amount of water addition for pretreatment,40%.Under these conditions,the extraction yield of essential oil was 0.92%.A total of 35 compounds were identified by GC-MS in the obtained essential oil with a total content of 91.06%,mostly consisting of ylangene(34.81%),β-himachalene(10.74%)andα-bergamotene(9.22%).The ICs0 value of the essential oil against DPPH free radicals was determined as 3.01 mg/mL.In conclusion,solvent-free microwave extraction is a feasible method for essential oil extraction from Schisandra chinensis fruits.展开更多
文摘The influence of chemical composition on corrosion resistance of AZ91D magnesium alloys ingots has been investigated. Mass loss method was applied to evaluate the corrosion resistance of AZ91D alloys and the data were analyzed by multiple regression. The results show that the corrosion resistance of this alloy can be improved by increasing Al, Zn and Mn in a certain degree, and will drop with increasing Si and heavy metals (Fe, Cu, Ni). It is found that ingots received from company F should be listed into unusable materials in terms of the corrosion resistance, while among the five suppliers, the only local company E supplied excellent AZ91D magnesium alloy ingots with the best corrosion resistance.
基金Project (FANEDD 200545) supported by the Foundation for the Author of National Excellent Doctoral Dissertation of China Project (50408019) supported by the National Natural Science Foundation of China Project (2008BAJ12B03) supported by National Key Project of Scientific and Technical Supporting Programs of China
文摘Source apportionment of particulate matters with aerodynamic diameter less than 10 μm （PM10） was conducted in the suburban area of Changsha, China. PM10 samples for 24 h collected with TEOM 1400a and ACCU system in July and October 2008 were chemically analyzed by the wavelength dispersive X-ray fluorescence （WD-XRF）. Source appointment was implemented by the principal component analysis/absolute principal component analysis （PCA/APCA） to identify the possible sources and to quantify the contributions of the sources to PM10. Results show that as the PM10 concentration is increased from （85.6±43.7） μg/m3 in July 2008 to （107.6±35.7） μg/m^3 in October 2008, the concentrations of the anthropogenic elements （P, S, C1, K, Mn, Ni, Cu, Zn, and Pb） are basically increased but concentrations of the natural elements （Na, Mg, Al, Si, Ca, Ti, and Fe） are essentially decreased. Six main sources of PM10 are identified in the suburban of Changsha, China： soil dust, secondary aerosols, domestic oil combustion, waste incineration, traffic emission, and industrial emission contribute 57.7%, 24.0%, 9.8%, 5.0%, 2.0%, and 1.5%, respectively. Soil dust and secondary aerosols are the two major sources of particulate air pollution in suburban area of Changsha, China, so effective measures should be taken to control these two particulate pollutants.
基金Project(51304041) supported by the National Natural Science Foundation of ChinaProject(N100402015) supported by Fundamental Research Funds for the Central Universities of China+1 种基金Project(2012AA03A502) supported by the National High Technology Research and Development Program of ChinaProject supported by Program for Liaoning Innovative Research Team in University,China
文摘The influence of chemical composition and cold deformation on aging precipitation behavior of 18Cr-16Mn-2Mo-I.IN （HNS-A）, 18Cr-16Mn-I.3N （HNS-B）, 18Cr-18Mn-2Mo-0.96N （HNS-C） and 18Cr-18Mn-2Mo-0.77N （I-INS-D） high nitrogen austenitic stainless steels was investigated. The results show that the ＂nose＂ temperatures and incubation periods of the initial time-temperature-precipitation （TTP） curves of aged HNSs are found to be 850 ℃, 60 s; 850 ℃, 45 s; 850 ℃, 60 s and 900 ℃, 90 s, respectively. Based on the analysis of SAD patterns, the coarse cellular Cr2N precipitate which presents a lamellar structure has a hexagonal structure of a=0.478 nm and c=0.444 nm. The Z phase corresponding to a composition of Fe36Cr^2Mo10, is determined to be a body-centered cubic structure ofa=0.892 nm. The precipitating sensitivity presents no more difference with the nitrogen content increasing from 0.77% to 0.96%, but exhibits so obviously that the cellular precipitates nearly overspread the whole field. The addition of Mo element can restrain the TTP curves moving left and down, which means decreasing the sensitivity of aging precipitation. With increasing the cold deformation, the sensitivity of precipitation increases obviously.
文摘Two experiments were conducted to study the effects of variety and maturity stage on chemical composition and in vitro dry matter degradability of oat and barley forages. In exp1, four oat varieties and one barley variety were harvested at three maturity stages: stage 1, Two weeks before stage 2; stage 2, Mid-dough for oat and early-dough for barley; stage 3, One week after stage 2. All samples were analyzed for DM, CP, ether extract, ash, ADF(acid detergent fiber), NDF(neutral detergent fiber), ADL(acid detergent lignin), NDICP(neutral detergent insoluble crude protein) and IVDMD(In vitro dry matter digestibility). There was no difference in chemical components and IVDMD among oat variety. But maturity stage had a profound influence on some nutrient contents and IVDMD. With maturity advancing, CP decreased from15.5% to 11.03% and from 14.7% to 10.9% at stage 1 and stage 2 for oat and for barley, respectively, and IVDMD decreased slowly from 72.0% to 64.9% and from 73.5% to 68.8% for oat and for barley, respectively. For fiber fractions, NDF declined before stage 2 and then level off after stage 2, while ADF changed little throughout maturation. The ADL trended to increase with increased maturity. The results from the present experiment revealed that Bailor has relatively greater IVDMD value and kept lower ADL content than any other cultivars. The observed variation in chemical composition and ruminal digestibility among various oat cultivars would allow breeders choose suitable oat forages for cattle diet. In experiment. 2, the DaisyⅡ incubator was used to compare IVDMD values of forages of seven oat cultivars using rumen fluid or faecal liquor as the inoculum source. There was a strong linear relationship between the two estimates (R 2 = 0.809; P < 0.001), which indicated that fecal liquor method has the potential to be used instead of rumen fluid for estimation of in vitro digestibility of forage. It is suggested the method for determination of IVDMD using faecal liquor was appropriate for batch operation with precision and efficiency.
基金the Doctoral Research Initiation Foundation of Changzhi Medical College(BS202005)。
文摘This study was to investigate the effects of three exogenous substances on chemical constituents of Isatis indigotica leavesand their efficacy in alleviating drought stress, and explore the methods of applying exogenous substances to efficient cultivationof Isatis indigotica. Polyethylene glycol (PEG) was used to simulate drought stress to deal with seeds of Isatis indigotica at thegermination stage (concentration: 0, 10%, 15%, and 20%). Simultaneous operation of exogenous growth regulators [microbialinoculum (MI), γ-aminobutyric acid (GABA) and salicylic acid (SA)] and PEG were implemented in seeds of Isatis indigotica.The effects of drought stress and the mitigation of exogenous substances were observed by statistics of seed germination potential,germination rate, hypocotyl length, and radicle length of each treatment. The effects of exogenous substances on the content ofalkaloids, crude protein and free amino acids in the leaves of Isatis indigotica grown in a greenhouse were determined after sprayingexogenous substances on the plants. The differences of germination potential, germination rate, hypocotyl length, and radicle lengthamong 15% PEG stress treatment, 10% PEG stress treatment and the control were significant (P<0.05). According to the predesignedgermination standard, the seeds did not germinate under 20% PEG stress treatment. When the PEG concentration was 15%, the resultsof seed germination potential and germination rate after adding MI were significantly different from those under stress alone (P<0.05).When exposed to 10% PEG stress, the supplementation of GABA led to a notable increase in radicle length of Isatis indigotica seeds,showing significant differences compared to other three treatments. The application of MI and GABA under 15% PEG stress resultedin a significant increase in the radicle and hypocotyl length of Isatis indigotica seeds compared to other two treatments. The contentof the total alkaloids in leaves of Isatis indigotica was significantly increased after spraying GABA. Meanwhile, the contents of crudeprotein and the total free amino acids were kept constant after spraying exogenous substances. Application of MI and GABA couldalleviate drought stress of Isatis indigotica. The content of the total alkaloids in leaves of Isatis indigotica could significantly increaseafter spraying GABA.
文摘This study was undertaken to optimize the solvent-free microwave extraction conditions and DPPH radicalscavenging activity of essential oil from Schisandra chinesis fruits.The uniform design method was employed for process optimization.The optimal extraction conditions were determined as follows:extraction time,50 rain;microwave power,800 W;and amount of water addition for pretreatment,40%.Under these conditions,the extraction yield of essential oil was 0.92%.A total of 35 compounds were identified by GC-MS in the obtained essential oil with a total content of 91.06%,mostly consisting of ylangene(34.81%),β-himachalene(10.74%)andα-bergamotene(9.22%).The ICs0 value of the essential oil against DPPH free radicals was determined as 3.01 mg/mL.In conclusion,solvent-free microwave extraction is a feasible method for essential oil extraction from Schisandra chinensis fruits.
