Evacuation assistants are expected to spread the escape route information and lead evacuees toward the exit as quickly as possible. Their leading behavior influences the evacuees＇ movement directly, which is confirme...Evacuation assistants are expected to spread the escape route information and lead evacuees toward the exit as quickly as possible. Their leading behavior influences the evacuees＇ movement directly, which is confirmed to be a decisive factor of the evacuation efficiency. The transmission process of escape information and its function on the evacuees＇ movement are accurately presented by the proposed extended dynamic communication field model. For evacuation assistants and eevacuees, their sensitivity parameter of static floor field（SFF）, kL S, and kS, are fully discussed. The simulation results e indicate that the appropriate kL Sis associated with the maximum kSof evacuees. The optimal combinations of kL Sand e kSwere found to reach the highest evacuation efficiency. There also exists an optimal value for evacuation assistants＇ information transmission radius.展开更多
The thermodynamic behavior of twin-roll casting （TRC） lead alloy strip process directly affects the forming of the lead strip, the quality of the lead strip and the production efficiency. However, there is little re...The thermodynamic behavior of twin-roll casting （TRC） lead alloy strip process directly affects the forming of the lead strip, the quality of the lead strip and the production efficiency. However, there is little research on the thermodynamics of lead alloy strip at home and abroad. The TRC lead process is studied in four parameters： the pouring temperature of molten lead, the depth of molten pool, the roll casting speed, and the rolling thickness of continuous casting. Firstly, the thermodynamic model for TRC lead process is built. Secondly, the thermodynamic behavior of the TRC process is simulated with the use of Fluent. Through the thermodynamics research and analysis, the process parameters of cast rolling lead strip can be obtained： the pouring temperature of molten lead： 360-400 ℃, the depth of molten pool： 250-300 mm, the roll casting speed： 2.5-3 m/min, the rolling thickness： 8-9 mm. Based on the above process parameters, the optimal parameters（the pouring temperature of molten lead： 375-390 ℃, the depth of molten pool： 285-300 mm, the roll casting speed： 2.75-3 m/min, the rolling thickness： 8.5-9 mm） can be gained with the use of the orthogonal experiment. Finally, the engineering test of TRC lead alloy strip is carried out and the test proves the thermodynamic model is scientific, necessary and correct. In this paper, a detailed study on the thermodynamic behavior of lead alloy strip is carried out and the process parameters of lead strip forming are obtained through the research, which provide an effective theoretical guide for TRC lead alloy strip process.展开更多
Vaporization behavior （1163-1463 K） of lead in the slag system of FeO-CaO-SiO2-Al2O3 with CaC% was examined. A thermodynamic estimation with the principle of Gibbs free energy minimization showed that the major vapo...Vaporization behavior （1163-1463 K） of lead in the slag system of FeO-CaO-SiO2-Al2O3 with CaC% was examined. A thermodynamic estimation with the principle of Gibbs free energy minimization showed that the major vapor species from the sample of the FeO-CaO-SiO2-Al2O3 system＋PbO＋CaCl2 were metallic Pb, PbCl, PbCl2, and FeCl2, at the experimental temperature range. The experimental results show that the mole ratio of vaporized Cl in lead chlorides to vaporized Pb, simply expressed as Cl/Pb decreases with increasing temperature. The larger Cl/Pb means a larger ratio of gaseous PbCl2, since metallic Pb and PbCl vapors are formed in a similar reduction atmosphere. The evaporation is initially rapid and becomes steady after holding for 10 min. Gaseous PbCl2 is mainly formed during the heating period, and at the holding stage, it reacts with FeO to produce gaseous FeCl2 With regard to slag composition, FeO content and basicity significantly affect the evaporation of lead. High FeO content and high basicity promotes the formation of metallic Pb and PbCI, whereas, it prohibits PbCl2 evaporation.展开更多
A novel molten salt extraction process consisting of chlorination roasting and molten salt electrolysis was proposed to develop a more efficient and environmental friendly technology for recovering lead from spent lea...A novel molten salt extraction process consisting of chlorination roasting and molten salt electrolysis was proposed to develop a more efficient and environmental friendly technology for recovering lead from spent lead acid batteries(LABs).The feasibility of this process was firstly assessed based on thermodynamics fundamentals.The electrochemical behavior of Pb(II)on a tungsten electrode in the eutectic NaCl−KCl melts at 700℃ was then investigated in detail by transient electrochemical techniques.The results indicated that the reduction reaction of Pb(II)in NaCl−KCl melts was a one-step process exchanging two electrons,and it was determined to be a quasi-reversible diffusion-controlled process.Finally,potentiostatic electrolysis was carried out at−0.6 V(vs Ag/AgCl)in the NaCl−KCl−PbCl2 melts,and the obtained cathodic product was identified as pure Pb by X-ray diffraction analysis.This investigation demonstrated that it is practically feasible to produce pure Pb metal by electrochemical reduction of PbCl2 in eutectic NaCl−KCl melts,and has provided important fundamental for the further study on lead recovery from spent LABs via molten salt extraction process.展开更多
A field study was conducted to determine the behavior and distribution of arsenic during the pyrometallurgy process in a typical SKS(Shuikoushan) lead smelter in Hunan province, China. Environmental influences of arse...A field study was conducted to determine the behavior and distribution of arsenic during the pyrometallurgy process in a typical SKS(Shuikoushan) lead smelter in Hunan province, China. Environmental influences of arsenic in selected samples were evaluated. Arsenic contents in all input and output samples vary from 0.11% in raw lead to 6.66% in collected dust-2. More arsenic is volatilized in blast furnace and fuming furnace(73.02% of arsenic input) than bottom blowing furnace(10.29% of arsenic input).There are 78.97%, 13.69%, 7.31% of total arsenic distributed in intermediate materials, stockpiled materials and unorganized emissions, respectively. Matte slag-2, collected dust-1 and secondary zinc oxide are hazardous based on the arsenic concentrations of toxicity characteristic leaching procedure. According to risk assessment code(RAC) guideline, arsenic in collected dust-1 poses a very serious risk to the surrounding environment, arsenic in speiss, matte slag-2, water-quenched slag and secondary zinc oxide show low risk, while arsenic in matte slag-1, collected dust-2 and post dust has no risk to the environment.展开更多
The behaviors of lead zirconate titanate （PZT） deposited as the dielectric for high-voltage devices are investigated experimentally and theoretically. The devices demonstrate not only high breakdown voltages above 3...The behaviors of lead zirconate titanate （PZT） deposited as the dielectric for high-voltage devices are investigated experimentally and theoretically. The devices demonstrate not only high breakdown voltages above 350 V, but also excellent memory behaviors. A drain current–gate voltage （ID-VG） memory window of about 2.2 V is obtained at the sweep voltages of ±10 V for the 350-V laterally diffused metal oxide semiconductor （LDMOS）. The retention time of about 270 s is recorded for the LDMOS through a controlled ID-VG measurement. The LDMOS with memory behaviors has potential to be applied in future power conversion circuits to boost the performance of the energy conversion system.展开更多
The study treated 72 s,rague-Dawley rats that were divided into 4 groups, one controlgroup and low, middle and higa dose groups, through drinking lead acetate solutions for threemonths. On the basis of founding subcl...The study treated 72 s,rague-Dawley rats that were divided into 4 groups, one controlgroup and low, middle and higa dose groups, through drinking lead acetate solutions for threemonths. On the basis of founding subclinical lead poisoning model, behavioral toxicological testwhich consisted of neurobehavioral functions, neuroelectrophysiology and neurobiochemistry wascarried out. The results indicabo that low lvel lead exposure could result in the obvious changes orneurobehavioral function, neuroelectrophyslology and ueurobiochemistry, and the changes of neurobeltavioral runctiou had close correlatiom with P6B, Zap, NCV and DA, and they also had promlnant dose-response relatiouskips. The results suggested that the indexes of neurobehavioral functionmight be cousldered as early, semitive indexes for subolinical'lead poisoning. The combination ofneurobehavioral function with neuroectrophysiology could be used to evaluate the early neurotic toxicity of lead. The results also suggested that the change of dopamine metabolism of the central nervous system (CNS) might be one of the biological foundation of lead neurotic toxicity which changedthe neurobehavioral function of laboratory rats.展开更多
In this study, shear tests have been performed on the as-reflowed Sn3.5Ag solder bumps and joints to investigate the deformation behavior of Sn3.5Ag lead-free solder samples. Scanning electron microscopy （SEM） was e...In this study, shear tests have been performed on the as-reflowed Sn3.5Ag solder bumps and joints to investigate the deformation behavior of Sn3.5Ag lead-free solder samples. Scanning electron microscopy （SEM） was employed to characterize the microstructures of the samples and orientation imaging microscopy （OIM） with electron backscattered diffraction （EBSD） in SEM was used to obtain crystallographic orientation of grains to provide a detailed characterization of the deformation behavior in Sn3.5Ag solder samples after shear tests. The deformation behavior in solder samples under shear stress was discussed. The experimental results suggest that the dynamic recrystallization could occur under shear stress at room temperature and recrystallized grains should evolve from subgrains by rotation. Compared with that of non-recrystallized and as-reflowed microstructures, the microhardness of the recrystallized microstructure decreased after shear tests.展开更多
The transformation behaviors of Pb fractions during composting of Pb-polluted waste without inoculants and with the inoculants of Phanerochaete chrysosporium were studied.Results show that the active Pb ions with high...The transformation behaviors of Pb fractions during composting of Pb-polluted waste without inoculants and with the inoculants of Phanerochaete chrysosporium were studied.Results show that the active Pb ions with high toxicity and transferability are transformed into the inactive Pb with low toxicity and transferability,confirming that Pb ions can be efficiently immobilized during composting without or with the inoculants.The soluble-exchangeable Pb in composting without inoculants reaches 49.0 mg/kg at day 60,while that with the inoculants is reduced to 0 mg/kg dry mass compost.The higher contents of organic-bound Pb (59.0 mg/kg)and residual Pb(69.2 mg/kg)with low toxicity are found after 60-day composting with inoculants,compared with those without inoculants.The above data indicate the better immobilization effect of Pb and the greater alleviation of Pb hazards in composting with the inoculants of Phanerochaete chrysosporium than without inoculants,which may be due to the more microbial biomass and the higher pH value in composting of Pb-polluted waste with inoculants.展开更多
Whether the multi-biological toxicity from lead exposure could be transferred to progeny has not been clarified. In the present study, we explored the Caenorhabditis elegans to analyze the multiple toxicities from lea...Whether the multi-biological toxicity from lead exposure could be transferred to progeny has not been clarified. In the present study, we explored the Caenorhabditis elegans to analyze the multiple toxicities from lead exposure and their possibly transferable properties. The lead exposure could cause series of severe multi-biological defects with a concentration-dependent manner by affecting the endpoints of life span, development, reproduction and locomotion behaviors in nematodes. Moreover, most of these toxicities could be transferred to progeny from lead exposed animals and some of the defects in progeny appeared even more severe than in their parents, such as the body sizes and mean life spans. We summarized the defects caused by lead exposure into three groups according to their transferable properties or rescue patterns. That is, the defects caused by lead exposure could be largely, or partially, or became even more severe in progeny animals. Therefore, our results suggest that lead exposure can cause severely multi-biological defects, and most of these multiple toxicities can be considered as transferable for exposed animals in C. elegans.展开更多
The purpose of this study is to investigate the effects of collaboration with suppliers and lead users in new product development (NPD) on innovation behavior. Such collaborations are regarded as advanced forms of ext...The purpose of this study is to investigate the effects of collaboration with suppliers and lead users in new product development (NPD) on innovation behavior. Such collaborations are regarded as advanced forms of external alliances. Survey data from two hundred and fifty-two manufacturing companies were collected from the European Union. The results of multiple regression analysis showed that both suppliers’ and lead users’ collaboration in NPD significantly affected innovation behavior. Lead users’ collaboration showed higher impact on innovation behavior compared with suppliers’ collaboration.展开更多
Hypersonic vehicles are subjected to critical aerodynamic heating during flight,which poses a substantial challenge for the design of thermal protection systems(TPSs).Carbon-bonded carbon fiber(CBCF)composites are hig...Hypersonic vehicles are subjected to critical aerodynamic heating during flight,which poses a substantial challenge for the design of thermal protection systems(TPSs).Carbon-bonded carbon fiber(CBCF)composites are highly valuable materials for TPS in aerospace and military applications because of their lightweight structure and exceptional dimensional stability at elevated temperatures.However,these methods are constrained by a limited capacity for in-plane heat dissipation,which restricts their application under extreme thermal gradients.Therefore,incorporating enhanced in-plane directional heat-leading capabilities into CBCF composite designs represents a highly innovative approach that is expected to alleviate local thermal stress and achieve efficient thermal management.Herein,we propose a multifunctional design strategy involving the fabrication of SiBCN-modified carbon-bonded carbon fiber(CBCF/SiBCN)composites through the integration of high-efficiency in-plane heat conduction pathways with anisotropic thermal insulation structures.The preparation process,microscopic morphology,mechanical response and thermal performance of the CBCF/SiBCN composites were systematically investigated.The fabricated samples exhibited the compressive strength of 4.05-4.36 MPa in the in-plane direction and 1.30-1.36 MPa in the through-the-thickness direction,while maintaining the low density of 0.48-0.49 g·cm^(-3).Notably,the in-plane thermal conductivity of CBCF/SiBCN reached 60.9-61.5 W·m^(−1)·K^(−1)while remaining at 0.08 W·m^(−1)·K^(−1)in the direction of thermal insulation,demonstrating typical anisotropy and indicating significant potential for effective thermal management.This paper introduces an innovative design that focuses on the development of inplane directional heat-leading properties for thermally insulating composites,which potentially meet the critical requirements for thermal protection in aerospace applications.展开更多
HfCeSiC-modified carbon/carbon composite(C/CeHfCeSiC)sharp leading edges(SLEs)were prepared via precursor infiltration and pyrolysis for potential hypersonic applications.The effect of SiC proportion on the ablation b...HfCeSiC-modified carbon/carbon composite(C/CeHfCeSiC)sharp leading edges(SLEs)were prepared via precursor infiltration and pyrolysis for potential hypersonic applications.The effect of SiC proportion on the ablation behavior of the SLEs under oxyacetylene flames with 2.38 MW/m^(2) and 4.18 MW/m^(2) was investigated.The preferred sample with a volume ratio of HfC to SiC of 0.74 possessed almost zero degradation(linear recession rate 0.6 mm/s)up to a temperature of 2371℃.As the temperature increases to 2527℃ in the latter condition,the SLE with less SiC(the volume ratio of HfC to SiC is 1.10)exhibited a linear recession rate of 1.03 mm/s during cyclic ablation of 3×40 s.Relatively more SiC addition is favorable under lower heat flux due to the better oxygen barrier performance of the scale.However,superior ablation resistance is available under higher heat flux with less SiC addition due to the higher thermal stability of the resulting oxide scale.展开更多
基金Project supported by the National Basic Research Program of China(Grant No.2011CB706900)the National Natural Science Foundation of China(Grant Nos.71225007 and 71203006)+2 种基金the National Key Technology Research and Development Program of the Ministry of Science and Technology of China(Grant No.2012BAK13B06)the Humanities and Social Sciences Project of the Ministry of Education of China(Grant Nos.10YJA630221 and 12YJCZH023)the Beijing Philosophy and Social Sciences Planning Project of the Twelfth Five-Year Plan,China(Grant Nos.12JGC090 and 12JGC098)
文摘Evacuation assistants are expected to spread the escape route information and lead evacuees toward the exit as quickly as possible. Their leading behavior influences the evacuees＇ movement directly, which is confirmed to be a decisive factor of the evacuation efficiency. The transmission process of escape information and its function on the evacuees＇ movement are accurately presented by the proposed extended dynamic communication field model. For evacuation assistants and eevacuees, their sensitivity parameter of static floor field（SFF）, kL S, and kS, are fully discussed. The simulation results e indicate that the appropriate kL Sis associated with the maximum kSof evacuees. The optimal combinations of kL Sand e kSwere found to reach the highest evacuation efficiency. There also exists an optimal value for evacuation assistants＇ information transmission radius.
基金Supported by National Hi-tech Research and Development Program of China(863 Program,Grant No.2012AA063506)Natural Science Foundation of Jiangsu Higher Education Institutions of China(Grant No.14KJB460026)Suzhou Science and Technology Support Program of China(Grant No.SS201344)
文摘The thermodynamic behavior of twin-roll casting （TRC） lead alloy strip process directly affects the forming of the lead strip, the quality of the lead strip and the production efficiency. However, there is little research on the thermodynamics of lead alloy strip at home and abroad. The TRC lead process is studied in four parameters： the pouring temperature of molten lead, the depth of molten pool, the roll casting speed, and the rolling thickness of continuous casting. Firstly, the thermodynamic model for TRC lead process is built. Secondly, the thermodynamic behavior of the TRC process is simulated with the use of Fluent. Through the thermodynamics research and analysis, the process parameters of cast rolling lead strip can be obtained： the pouring temperature of molten lead： 360-400 ℃, the depth of molten pool： 250-300 mm, the roll casting speed： 2.5-3 m/min, the rolling thickness： 8-9 mm. Based on the above process parameters, the optimal parameters（the pouring temperature of molten lead： 375-390 ℃, the depth of molten pool： 285-300 mm, the roll casting speed： 2.75-3 m/min, the rolling thickness： 8.5-9 mm） can be gained with the use of the orthogonal experiment. Finally, the engineering test of TRC lead alloy strip is carried out and the test proves the thermodynamic model is scientific, necessary and correct. In this paper, a detailed study on the thermodynamic behavior of lead alloy strip is carried out and the process parameters of lead strip forming are obtained through the research, which provide an effective theoretical guide for TRC lead alloy strip process.
基金supported by the National Natural Science Foundation of China (No.50704004)
文摘Vaporization behavior （1163-1463 K） of lead in the slag system of FeO-CaO-SiO2-Al2O3 with CaC% was examined. A thermodynamic estimation with the principle of Gibbs free energy minimization showed that the major vapor species from the sample of the FeO-CaO-SiO2-Al2O3 system＋PbO＋CaCl2 were metallic Pb, PbCl, PbCl2, and FeCl2, at the experimental temperature range. The experimental results show that the mole ratio of vaporized Cl in lead chlorides to vaporized Pb, simply expressed as Cl/Pb decreases with increasing temperature. The larger Cl/Pb means a larger ratio of gaseous PbCl2, since metallic Pb and PbCl vapors are formed in a similar reduction atmosphere. The evaporation is initially rapid and becomes steady after holding for 10 min. Gaseous PbCl2 is mainly formed during the heating period, and at the holding stage, it reacts with FeO to produce gaseous FeCl2 With regard to slag composition, FeO content and basicity significantly affect the evaporation of lead. High FeO content and high basicity promotes the formation of metallic Pb and PbCI, whereas, it prohibits PbCl2 evaporation.
基金Project(gxyq2018012)supported by the Developing Program Foundation for the Excellent Youth Talents of Higher Education of Anhui Province,ChinaProject(SKF19-05)supported by Foundation of Anhui Province Key Laboratory of Metallurgical Engineering&Resources Recycling,ChinaProjects(51904003,U1703130)supported by the National Natural Science Foundation of China。
文摘A novel molten salt extraction process consisting of chlorination roasting and molten salt electrolysis was proposed to develop a more efficient and environmental friendly technology for recovering lead from spent lead acid batteries(LABs).The feasibility of this process was firstly assessed based on thermodynamics fundamentals.The electrochemical behavior of Pb(II)on a tungsten electrode in the eutectic NaCl−KCl melts at 700℃ was then investigated in detail by transient electrochemical techniques.The results indicated that the reduction reaction of Pb(II)in NaCl−KCl melts was a one-step process exchanging two electrons,and it was determined to be a quasi-reversible diffusion-controlled process.Finally,potentiostatic electrolysis was carried out at−0.6 V(vs Ag/AgCl)in the NaCl−KCl−PbCl2 melts,and the obtained cathodic product was identified as pure Pb by X-ray diffraction analysis.This investigation demonstrated that it is practically feasible to produce pure Pb metal by electrochemical reduction of PbCl2 in eutectic NaCl−KCl melts,and has provided important fundamental for the further study on lead recovery from spent LABs via molten salt extraction process.
基金Project(2011AA061001)supported by the National High Technology Research and Development Program of ChinaProject(51304251)supported by the National Natural Science Foundation of China+1 种基金Project(2013M542141)supported by China Postdoctoral FoundationProject(K1201010-61)supported by Planned Program of Science and Technology of Changsha,China
文摘A field study was conducted to determine the behavior and distribution of arsenic during the pyrometallurgy process in a typical SKS(Shuikoushan) lead smelter in Hunan province, China. Environmental influences of arsenic in selected samples were evaluated. Arsenic contents in all input and output samples vary from 0.11% in raw lead to 6.66% in collected dust-2. More arsenic is volatilized in blast furnace and fuming furnace(73.02% of arsenic input) than bottom blowing furnace(10.29% of arsenic input).There are 78.97%, 13.69%, 7.31% of total arsenic distributed in intermediate materials, stockpiled materials and unorganized emissions, respectively. Matte slag-2, collected dust-1 and secondary zinc oxide are hazardous based on the arsenic concentrations of toxicity characteristic leaching procedure. According to risk assessment code(RAC) guideline, arsenic in collected dust-1 poses a very serious risk to the surrounding environment, arsenic in speiss, matte slag-2, water-quenched slag and secondary zinc oxide show low risk, while arsenic in matte slag-1, collected dust-2 and post dust has no risk to the environment.
基金the National Basic Research Program of China(Grant No.50772019)the National Natural Science Foundation of China(Grant No.61204084)
文摘The behaviors of lead zirconate titanate （PZT） deposited as the dielectric for high-voltage devices are investigated experimentally and theoretically. The devices demonstrate not only high breakdown voltages above 350 V, but also excellent memory behaviors. A drain current–gate voltage （ID-VG） memory window of about 2.2 V is obtained at the sweep voltages of ±10 V for the 350-V laterally diffused metal oxide semiconductor （LDMOS）. The retention time of about 270 s is recorded for the LDMOS through a controlled ID-VG measurement. The LDMOS with memory behaviors has potential to be applied in future power conversion circuits to boost the performance of the energy conversion system.
文摘The study treated 72 s,rague-Dawley rats that were divided into 4 groups, one controlgroup and low, middle and higa dose groups, through drinking lead acetate solutions for threemonths. On the basis of founding subclinical lead poisoning model, behavioral toxicological testwhich consisted of neurobehavioral functions, neuroelectrophysiology and neurobiochemistry wascarried out. The results indicabo that low lvel lead exposure could result in the obvious changes orneurobehavioral function, neuroelectrophyslology and ueurobiochemistry, and the changes of neurobeltavioral runctiou had close correlatiom with P6B, Zap, NCV and DA, and they also had promlnant dose-response relatiouskips. The results suggested that the indexes of neurobehavioral functionmight be cousldered as early, semitive indexes for subolinical'lead poisoning. The combination ofneurobehavioral function with neuroectrophysiology could be used to evaluate the early neurotic toxicity of lead. The results also suggested that the change of dopamine metabolism of the central nervous system (CNS) might be one of the biological foundation of lead neurotic toxicity which changedthe neurobehavioral function of laboratory rats.
基金supported by the National Natural Science Foundation of China under Grant No.50905042the Shenzhen Special Funds for Overseas High-level Talents(No. KQC201109020053A)+1 种基金Shenzhen Technological Innovation Project (No.CXZZ20120829103358067)the Shenzhen Special Funds for Strategic Emerging Industries(No.JCYJ20120613140542764)
文摘In this study, shear tests have been performed on the as-reflowed Sn3.5Ag solder bumps and joints to investigate the deformation behavior of Sn3.5Ag lead-free solder samples. Scanning electron microscopy （SEM） was employed to characterize the microstructures of the samples and orientation imaging microscopy （OIM） with electron backscattered diffraction （EBSD） in SEM was used to obtain crystallographic orientation of grains to provide a detailed characterization of the deformation behavior in Sn3.5Ag solder samples after shear tests. The deformation behavior in solder samples under shear stress was discussed. The experimental results suggest that the dynamic recrystallization could occur under shear stress at room temperature and recrystallized grains should evolve from subgrains by rotation. Compared with that of non-recrystallized and as-reflowed microstructures, the microhardness of the recrystallized microstructure decreased after shear tests.
基金Project(50808073)supported by the National Natural Science Foundation of ChinaProject(2005CB724203)supported by the National Basic Research Program of China+1 种基金Project(2007)supported by the Program for Changjiang Scholars and Innovative Research Team in University,ChinaProject(2007185)supported by the Environmental Protection Technology Research Program of Hunan Province,China
文摘The transformation behaviors of Pb fractions during composting of Pb-polluted waste without inoculants and with the inoculants of Phanerochaete chrysosporium were studied.Results show that the active Pb ions with high toxicity and transferability are transformed into the inactive Pb with low toxicity and transferability,confirming that Pb ions can be efficiently immobilized during composting without or with the inoculants.The soluble-exchangeable Pb in composting without inoculants reaches 49.0 mg/kg at day 60,while that with the inoculants is reduced to 0 mg/kg dry mass compost.The higher contents of organic-bound Pb (59.0 mg/kg)and residual Pb(69.2 mg/kg)with low toxicity are found after 60-day composting with inoculants,compared with those without inoculants.The above data indicate the better immobilization effect of Pb and the greater alleviation of Pb hazards in composting with the inoculants of Phanerochaete chrysosporium than without inoculants,which may be due to the more microbial biomass and the higher pH value in composting of Pb-polluted waste with inoculants.
基金Project supported by the Southeast University Foundation for Excellent Young Scholars(No.4023001013)
文摘Whether the multi-biological toxicity from lead exposure could be transferred to progeny has not been clarified. In the present study, we explored the Caenorhabditis elegans to analyze the multiple toxicities from lead exposure and their possibly transferable properties. The lead exposure could cause series of severe multi-biological defects with a concentration-dependent manner by affecting the endpoints of life span, development, reproduction and locomotion behaviors in nematodes. Moreover, most of these toxicities could be transferred to progeny from lead exposed animals and some of the defects in progeny appeared even more severe than in their parents, such as the body sizes and mean life spans. We summarized the defects caused by lead exposure into three groups according to their transferable properties or rescue patterns. That is, the defects caused by lead exposure could be largely, or partially, or became even more severe in progeny animals. Therefore, our results suggest that lead exposure can cause severely multi-biological defects, and most of these multiple toxicities can be considered as transferable for exposed animals in C. elegans.
文摘The purpose of this study is to investigate the effects of collaboration with suppliers and lead users in new product development (NPD) on innovation behavior. Such collaborations are regarded as advanced forms of external alliances. Survey data from two hundred and fifty-two manufacturing companies were collected from the European Union. The results of multiple regression analysis showed that both suppliers’ and lead users’ collaboration in NPD significantly affected innovation behavior. Lead users’ collaboration showed higher impact on innovation behavior compared with suppliers’ collaboration.
基金supported by the National Natural Science Foundation of China(Nos.52472063 and 12090031)supported by the Fundamental Research Funds for the Central Universities.
文摘Hypersonic vehicles are subjected to critical aerodynamic heating during flight,which poses a substantial challenge for the design of thermal protection systems(TPSs).Carbon-bonded carbon fiber(CBCF)composites are highly valuable materials for TPS in aerospace and military applications because of their lightweight structure and exceptional dimensional stability at elevated temperatures.However,these methods are constrained by a limited capacity for in-plane heat dissipation,which restricts their application under extreme thermal gradients.Therefore,incorporating enhanced in-plane directional heat-leading capabilities into CBCF composite designs represents a highly innovative approach that is expected to alleviate local thermal stress and achieve efficient thermal management.Herein,we propose a multifunctional design strategy involving the fabrication of SiBCN-modified carbon-bonded carbon fiber(CBCF/SiBCN)composites through the integration of high-efficiency in-plane heat conduction pathways with anisotropic thermal insulation structures.The preparation process,microscopic morphology,mechanical response and thermal performance of the CBCF/SiBCN composites were systematically investigated.The fabricated samples exhibited the compressive strength of 4.05-4.36 MPa in the in-plane direction and 1.30-1.36 MPa in the through-the-thickness direction,while maintaining the low density of 0.48-0.49 g·cm^(-3).Notably,the in-plane thermal conductivity of CBCF/SiBCN reached 60.9-61.5 W·m^(−1)·K^(−1)while remaining at 0.08 W·m^(−1)·K^(−1)in the direction of thermal insulation,demonstrating typical anisotropy and indicating significant potential for effective thermal management.This paper introduces an innovative design that focuses on the development of inplane directional heat-leading properties for thermally insulating composites,which potentially meet the critical requirements for thermal protection in aerospace applications.
基金supported by the National Natural Science Foundations of China under Grant No.52293372the Key R&D projects in Shaanxi Province under Grant No.2023-YBGY-418the Fundamental Science Center for Aviation and Gas Turbine Engines under Grant No.P2021-A-IV-002-001.
文摘HfCeSiC-modified carbon/carbon composite(C/CeHfCeSiC)sharp leading edges(SLEs)were prepared via precursor infiltration and pyrolysis for potential hypersonic applications.The effect of SiC proportion on the ablation behavior of the SLEs under oxyacetylene flames with 2.38 MW/m^(2) and 4.18 MW/m^(2) was investigated.The preferred sample with a volume ratio of HfC to SiC of 0.74 possessed almost zero degradation(linear recession rate 0.6 mm/s)up to a temperature of 2371℃.As the temperature increases to 2527℃ in the latter condition,the SLE with less SiC(the volume ratio of HfC to SiC is 1.10)exhibited a linear recession rate of 1.03 mm/s during cyclic ablation of 3×40 s.Relatively more SiC addition is favorable under lower heat flux due to the better oxygen barrier performance of the scale.However,superior ablation resistance is available under higher heat flux with less SiC addition due to the higher thermal stability of the resulting oxide scale.
