Central region coarse grains and centerline segregation are common defects in aluminum ingots fabricated by direct chill(DC)casting.A double cooling field was introduced into the DC casting process to reduce these def...Central region coarse grains and centerline segregation are common defects in aluminum ingots fabricated by direct chill(DC)casting.A double cooling field was introduced into the DC casting process to reduce these defects,whereby the external cooling was supplied by the mold and water jets,and intercooling was achieved by inserting a rod of the same alloy into the molten pool along the central axis of the ingot.Rather than forming a good metallurgical interface during solid-liquid compound casting,in the present work,the purpose of inserting the rod is to enforce internal cooling and consequently decrease the sump depth.Moreover,the insertion provides more nucleation sites with the unmoltenα-Al particles.The structure and the macrosegregation of 2024 Al alloy ingots prepared by DC casting with and without the inserts were investigated.Results show that when the inserting position is 50 mm above the upper edge of the graphite ring,significant grain refinement in the central region of the ingot and a reduced centerline segregation are achieved.展开更多
Land use practice significantly affects soil properties. Soil is a major sink for atmospheric carbon, and soil organic carbon （SOC） is considered as an essential indicator of soil quality. The objective of this stud...Land use practice significantly affects soil properties. Soil is a major sink for atmospheric carbon, and soil organic carbon （SOC） is considered as an essential indicator of soil quality. The objective of this study was to assess the effects of N and P applied to Suaeda salsa on biomass production, SOC concentration, labile organic carbon （LOC） concentration, SOC pool and carbon management index （CMI） as well as the effect of the land use practice on soil quality of coastal tidal lands in east coastal region of China. The study provided relevant references for coastal exploitation, tidal land management and related study in other countries and regions. The field experiment was laid out in a randomized complete block design, consisting of four N-fertilization rates （0 （NO）, 60 （N1）, 120 （N2） and 180 kg ha-1 （N3））, three P-fertilization rates （0 （P0）, 70 （P1） and 105 kg ha-~ （P2）） and bare land without vegetation. N and P applied to S. salsa on coastal tidal lands significantly affected biomass production （above-ground biomass and roots）, bulk density （Pb）, available N and P, SOC, LOC, SOC pool and CMI. Using statistical analysis, significantly interactions in N and P were observed for biomass production and the dominant factor for S. salsa production was N in continuous 2-yr experiments. There were no significant interactions between N and P for SOC concentration, LOC concentration and SOC pool. However, significant interaction was obtained for CMI at the 0-20 cm depth and N played a dominant role in the variation of CMI. There were significant improvements for soil measured attributes and parameters, which suggested that increasing the rates of N and P significantly decreased Pb at the 0-20 cm depth and increased available N and P, SOC, LOC, SOC pool as well as CMI at both the 0-20 and 20-40 cm depth, respectively. By correlation analysis, there were significantly positive correlations between biomass （above- ground biomass and roots） and SOC as well as展开更多
Copper sulfide Cu2S is a p-type semiconducting compound that has attracted great attentions in the thermoelectric （TE） community most recently. Considering the intrinsic ultralow lattice thermal conductivity, the en...Copper sulfide Cu2S is a p-type semiconducting compound that has attracted great attentions in the thermoelectric （TE） community most recently. Considering the intrinsic ultralow lattice thermal conductivity, the enhancement of TE performance in CuzS should be achieved through improving its electrical transport properties. To achieve this goal, lithium element was doped into CuzS in this study. A series of Cu2_xLixS samples with different Li contents （x = 0, 0.005, 0.010, 0.050, and 0.100） was synthesized by the melting-annealing method. When x 〈 0.05, the Cuz_xLixS samples are stable and pure phases, having the same monoclinic structure with the pristine Cu2S at room temperature. The electrical conductivities in the Cu2_xLixS samples are greatly improved with the Li-doping content increasing due to the enhanced carrier concentrations. Meanwhile, doping Li into CuzS increases the ionic activation energy and lessens the influence of mobile Cu ions on the heat-carrying phonons. Thus, the thermal conductivities of the Li-doped Cu2S samples increase. A maximal figure of merit （zT） of 0.84 at 900 K is obtained in Cul.99Lio.018, about 133% improvement as compared with that in Cu2S matrix.展开更多
A prompt gamma-neutron activation analysis(PGNAA) system was developed to detect the iron content of iron ore concentrate. Because of the self-absorption effect of gamma-rays and neutrons, and the interference of chlo...A prompt gamma-neutron activation analysis(PGNAA) system was developed to detect the iron content of iron ore concentrate. Because of the self-absorption effect of gamma-rays and neutrons, and the interference of chlorine in the neutron field, the linear relationship between the iron analytical coefficient and total iron content was poor, increasing the error in the quantitative analysis. To solve this problem, gamma-ray self-absorption compensation and a neutron field correction algorithm were proposed, and the experimental results have been corrected using this algorithm. The results show that the linear relationship between the iron analytical coefficient and total iron content was considerably improved after the correction. The linear correlation coefficients reached 0.99 or more.展开更多
Sinter is the main raw material in the blast furnace iron-making process,and basicity(CaO/SiO2)is an important quality index of sinter.Prompt gamma neutron activation analysis is a multi-elemental online detection tec...Sinter is the main raw material in the blast furnace iron-making process,and basicity(CaO/SiO2)is an important quality index of sinter.Prompt gamma neutron activation analysis is a multi-elemental online detection technology that has been successfully applied in cement,coal,etc.Compared with cement as a raw material,sinter exhibits poor moderation ability and a large neutron absorption cross section.Therefore,cement detection devices are not suitable for sinter mixture detection.In this study,a prompt gamma neutron activation analysis equipment used for testing cement was re-optimized to render it suitable for measuring a sinter mixture.Using Monte Carlo simulation,the comprehensive detection efficiency of the detection device improved by 71.52%.Because of the gamma-ray self-shielding effect of the sinter mixture,the detection errors of CaO and SiO2 are significant.By applying the gamma-ray self-shielding correction algorithm,the detection accuracies improved,and their linear correlation coefficients R2 exceeded 0.99.Furthermore,by applying an improved analyzer to a sintering plant,the first-grade product rate of the factory increased by 4.64%.展开更多
Background Maternal smoking during pregnancy may be associated with low birth weight(LBW)in offspring and global risk estimates have not been summarized previously.We aimed to systematically explore evidence regarding...Background Maternal smoking during pregnancy may be associated with low birth weight(LBW)in offspring and global risk estimates have not been summarized previously.We aimed to systematically explore evidence regarding maternal smoking and the LBW risk in offspring globally and examine possible causes of heterogeneity across relevant studies.Methods Comprehensive search of PubMed,Ovid Embase,Ovid Medline(R),and Web of science from inception until October 2021 was carried out.A random-effects meta-analysis was used to estimate the pooled odds ratio(OR)and corresponding 95%confidence interval(CI).Restricted cubic spline analysis with three knots was used to further examine the dose-response relationship.Results Literature searches yielded 4940 articles,of which 53 met inclusion criteria(comprising 55 independent studies).Maternal smoking during pregnancy was significantly associated with the risk of LBW in offspring(OR=1.89,95%CI=1.80-1.98).Furthermore,an obvious dose-response relationship between the amount of cigarettes daily smoked in pregnancy and the risk of LBW in offspring was observed.The results of subgroup analyses indicated that the risk of maternal smoking on LBW was larger in more recently conducted studies(P=0.020)and longer period of active smoking during pregnancy(P=0.002).No evidence of publication bias was found.Conclusions In summary,maternal smoking in pregnancy was significantly associated with a higher risk of LBW in offspring on a global scale.The risk of maternal smoking on infant LBW seems to be increasing over time,and was higher with longer smoking duration throughout pregnancy and more cigarettes smoked daily.展开更多
基金financially supported by the Natural Science Foundation of Liaoning Province(Nos.2019-ZD-0002,2019KF-0503)the Fundamental Research Funds for the Central Universities(Nos.N2002025,N2109006)the National Natural Science Foundation of China(No.51674078)。
文摘Central region coarse grains and centerline segregation are common defects in aluminum ingots fabricated by direct chill(DC)casting.A double cooling field was introduced into the DC casting process to reduce these defects,whereby the external cooling was supplied by the mold and water jets,and intercooling was achieved by inserting a rod of the same alloy into the molten pool along the central axis of the ingot.Rather than forming a good metallurgical interface during solid-liquid compound casting,in the present work,the purpose of inserting the rod is to enforce internal cooling and consequently decrease the sump depth.Moreover,the insertion provides more nucleation sites with the unmoltenα-Al particles.The structure and the macrosegregation of 2024 Al alloy ingots prepared by DC casting with and without the inserts were investigated.Results show that when the inserting position is 50 mm above the upper edge of the graphite ring,significant grain refinement in the central region of the ingot and a reduced centerline segregation are achieved.
基金support of the Special Fund for Public-Welfare Industrial (Agriculture) Research of China (200903001)the National Natural Science Foundation of China (41171181,41101199)+1 种基金the Key Technology R&D Program of Jiangsu Province, China (BE2010313)the Prospective Project of Production Education Research Cooperation of Jiangsu Province, China (BY2010013)
文摘Land use practice significantly affects soil properties. Soil is a major sink for atmospheric carbon, and soil organic carbon （SOC） is considered as an essential indicator of soil quality. The objective of this study was to assess the effects of N and P applied to Suaeda salsa on biomass production, SOC concentration, labile organic carbon （LOC） concentration, SOC pool and carbon management index （CMI） as well as the effect of the land use practice on soil quality of coastal tidal lands in east coastal region of China. The study provided relevant references for coastal exploitation, tidal land management and related study in other countries and regions. The field experiment was laid out in a randomized complete block design, consisting of four N-fertilization rates （0 （NO）, 60 （N1）, 120 （N2） and 180 kg ha-1 （N3））, three P-fertilization rates （0 （P0）, 70 （P1） and 105 kg ha-~ （P2）） and bare land without vegetation. N and P applied to S. salsa on coastal tidal lands significantly affected biomass production （above-ground biomass and roots）, bulk density （Pb）, available N and P, SOC, LOC, SOC pool and CMI. Using statistical analysis, significantly interactions in N and P were observed for biomass production and the dominant factor for S. salsa production was N in continuous 2-yr experiments. There were no significant interactions between N and P for SOC concentration, LOC concentration and SOC pool. However, significant interaction was obtained for CMI at the 0-20 cm depth and N played a dominant role in the variation of CMI. There were significant improvements for soil measured attributes and parameters, which suggested that increasing the rates of N and P significantly decreased Pb at the 0-20 cm depth and increased available N and P, SOC, LOC, SOC pool as well as CMI at both the 0-20 and 20-40 cm depth, respectively. By correlation analysis, there were significantly positive correlations between biomass （above- ground biomass and roots） and SOC as well as
基金financially supported by the National Natural Science Foundation of China (Nos. 51472262 and 51625205)the Key Research Program of Chinese Academy of Sciences (No.KFZD-SW-421)the Shanghai Government (No. 15JC1400301)
文摘Copper sulfide Cu2S is a p-type semiconducting compound that has attracted great attentions in the thermoelectric （TE） community most recently. Considering the intrinsic ultralow lattice thermal conductivity, the enhancement of TE performance in CuzS should be achieved through improving its electrical transport properties. To achieve this goal, lithium element was doped into CuzS in this study. A series of Cu2_xLixS samples with different Li contents （x = 0, 0.005, 0.010, 0.050, and 0.100） was synthesized by the melting-annealing method. When x 〈 0.05, the Cuz_xLixS samples are stable and pure phases, having the same monoclinic structure with the pristine Cu2S at room temperature. The electrical conductivities in the Cu2_xLixS samples are greatly improved with the Li-doping content increasing due to the enhanced carrier concentrations. Meanwhile, doping Li into CuzS increases the ionic activation energy and lessens the influence of mobile Cu ions on the heat-carrying phonons. Thus, the thermal conductivities of the Li-doped Cu2S samples increase. A maximal figure of merit （zT） of 0.84 at 900 K is obtained in Cul.99Lio.018, about 133% improvement as compared with that in Cu2S matrix.
基金supported by the National Key Scientific Instrument and Equipment Development Projects(No.2012YQ240121)Liaoning science and technology project(No.2017220010)Changchun Science and Technology Bureau Local Company and College(University,Institution)Cooperation Projects(No.17DY023)
文摘A prompt gamma-neutron activation analysis(PGNAA) system was developed to detect the iron content of iron ore concentrate. Because of the self-absorption effect of gamma-rays and neutrons, and the interference of chlorine in the neutron field, the linear relationship between the iron analytical coefficient and total iron content was poor, increasing the error in the quantitative analysis. To solve this problem, gamma-ray self-absorption compensation and a neutron field correction algorithm were proposed, and the experimental results have been corrected using this algorithm. The results show that the linear relationship between the iron analytical coefficient and total iron content was considerably improved after the correction. The linear correlation coefficients reached 0.99 or more.
基金This work was supported by the National Key Scientific Instrument and Equipment Development Projects(No.2012YQ240121)Liaoning Science and Technology Project(No.2017220010)the Major Special Science and Technology Plan of Liaoning Province in 2020(No.2020JH1/10100009).
文摘Sinter is the main raw material in the blast furnace iron-making process,and basicity(CaO/SiO2)is an important quality index of sinter.Prompt gamma neutron activation analysis is a multi-elemental online detection technology that has been successfully applied in cement,coal,etc.Compared with cement as a raw material,sinter exhibits poor moderation ability and a large neutron absorption cross section.Therefore,cement detection devices are not suitable for sinter mixture detection.In this study,a prompt gamma neutron activation analysis equipment used for testing cement was re-optimized to render it suitable for measuring a sinter mixture.Using Monte Carlo simulation,the comprehensive detection efficiency of the detection device improved by 71.52%.Because of the gamma-ray self-shielding effect of the sinter mixture,the detection errors of CaO and SiO2 are significant.By applying the gamma-ray self-shielding correction algorithm,the detection accuracies improved,and their linear correlation coefficients R2 exceeded 0.99.Furthermore,by applying an improved analyzer to a sintering plant,the first-grade product rate of the factory increased by 4.64%.
基金This study was funded by the by the National Social Science Foundation of China(Grant No.18ZDA085).
文摘Background Maternal smoking during pregnancy may be associated with low birth weight(LBW)in offspring and global risk estimates have not been summarized previously.We aimed to systematically explore evidence regarding maternal smoking and the LBW risk in offspring globally and examine possible causes of heterogeneity across relevant studies.Methods Comprehensive search of PubMed,Ovid Embase,Ovid Medline(R),and Web of science from inception until October 2021 was carried out.A random-effects meta-analysis was used to estimate the pooled odds ratio(OR)and corresponding 95%confidence interval(CI).Restricted cubic spline analysis with three knots was used to further examine the dose-response relationship.Results Literature searches yielded 4940 articles,of which 53 met inclusion criteria(comprising 55 independent studies).Maternal smoking during pregnancy was significantly associated with the risk of LBW in offspring(OR=1.89,95%CI=1.80-1.98).Furthermore,an obvious dose-response relationship between the amount of cigarettes daily smoked in pregnancy and the risk of LBW in offspring was observed.The results of subgroup analyses indicated that the risk of maternal smoking on LBW was larger in more recently conducted studies(P=0.020)and longer period of active smoking during pregnancy(P=0.002).No evidence of publication bias was found.Conclusions In summary,maternal smoking in pregnancy was significantly associated with a higher risk of LBW in offspring on a global scale.The risk of maternal smoking on infant LBW seems to be increasing over time,and was higher with longer smoking duration throughout pregnancy and more cigarettes smoked daily.
