Catalytic performance of supported metal catalysts not only depends on the reactivity of metal,but also the adsorption and diffusion properties of gas molecules which are usually affected by many factors,such as tempe...Catalytic performance of supported metal catalysts not only depends on the reactivity of metal,but also the adsorption and diffusion properties of gas molecules which are usually affected by many factors,such as temperature,pressure,properties of metal clusters and substrates,etc.To explore the impact of each of these macroscopic factors,we simulated the movement of CO molecules confined in graphene nanoslits with or without supported Pt nanoparticles.The results of molecular dynamics simulations show that the diffusion of gas molecules is accelerated with high temperature,low pressure or low surface-atom number of supported metals.Notably,the supported metal nanoparticles greatly affect the gas diffusion due to the adsorption of gas molecules.Furthermore,to bridge a quantitative relationship between microscopic simulation and macroscopic properties,a generalized formula is derived from the simulation data to calculate the diffusion coefficient.This work helps to advise the diffusion modulation of gas molecules via structural design of catalysts and regulation of reaction conditions.展开更多
Development of hydrothermally stable,low-temperature catalysts for controlling nitrogen oxides emissions from mobile sources remains an urgent challenge.We have prepared a metal oxide-zeolite composite catalyst by dep...Development of hydrothermally stable,low-temperature catalysts for controlling nitrogen oxides emissions from mobile sources remains an urgent challenge.We have prepared a metal oxide-zeolite composite catalyst by depositing Mn active species on a mixture support of CeO_(2)/Al_(2)O_(3) and ZSM-5.This composite catalyst is hydrothermally stable and shows improved low-temperature SCR activity and significantly reduced N_(2)O formation than the corresponding metal oxide catalyst.Comparing with a Cu-CHA catalyst,the composite catalyst has a faster response to NH_(3) injection and less NH_(3) slip.Our characterization results reveal that such an oxide-zeolite composite catalyst contains more acidic sites and Mn^(3+)species as a result of oxide-zeolite interaction,and this interaction leads to the generation of more NH_(4)^(+)species bound to the Br?nsted acid sites and more reactive NOxspecies absorbed on the Mn sites.Herein,we report our mechanistic understanding of the oxide-zeolite composite catalyst and its molecular pathway for improving the low-temperature activity and N_(2) selectivity for NH_(3)-SCR reaction.Practically,this work may provide an alternative methodology for low-temperature NO_(x) control from diesel vehicles.展开更多
Hydrous iron oxide and hydrous aluminum oxide were loaded successfully onto a polymeric adsorbent(D301) to modify adsorbing materials(HIOD301 and HAOD301). The adsorptive equilibrium of atrazine was investigated in an...Hydrous iron oxide and hydrous aluminum oxide were loaded successfully onto a polymeric adsorbent(D301) to modify adsorbing materials(HIOD301 and HAOD301). The adsorptive equilibrium of atrazine was investigated in an aquatic environment using HIOD301 and HAOD301 under different experimental conditions. The results indicated that both HIOD301 and HAOD301 showed good adsorption capacities for atrazine at p H 4. The Langmuir and Freundlich isotherm equations were used to study the interactions between the adsorbate and adsorbent.The adsorption kinetics of atrazine at different concentrations was well described in terms of a pseudosecond-order equation in regard to the correlation coefficients and adsorption capacity. The removal percentages of atrazine for HIOD301 and HAOD301 were still more than 95% in the presence of sodium chloride.展开更多
Background Soil-transmitted helminths(STHs)were previously endemic in Shandong Province,China.This study aimed to analyze the STHs prevalence trend and the natural,social,and human cognitive and behavioural factors in...Background Soil-transmitted helminths(STHs)were previously endemic in Shandong Province,China.This study aimed to analyze the STHs prevalence trend and the natural,social,and human cognitive and behavioural factors infuencing the discrepancies between high and low infection levels from 2016 to 2020 in Shandong Province in eastern China.Methods STHs surveillance data of Shandong Province from 2016 to 2020 were obtained from China Information Management System for Prevention and Control of Parasitic Diseases.STHs infections were detected by modifed Kato–Katz method.Comprehensive information on the natural and social factors,STHs-related knowledge and behaviours were collected through questionnaire surveys.Retrospective spatial scan analysis was performed using SaTScan v10.1 to evaluate any identifed spatial clusters of STHs infection for statistical signifcance and Bayes discriminant analysis was used to discriminate the high or low infection groups of the villages.Results In total,72,160 participants were involved in our survey from 2016 to 2020.The overall STHs prevalence rate was 1.13%,with the eastern region of Shandong Province having the highest rate(2.02%).The predominant species was T.trichiura,with the prevalence rate of 0.99%and the≥70-year age group possessed the highest rate of 2.21%.The STHs prevalence rate showed an annual linear downward trend from 2016 to 2020(χ_(trend)^(2) =127.600,P<0.001).Respondents aged≥60 years had the lowest awareness level of STHs-related prevention knowledge(all P<0.05),and were the most likely to adopt the practice of fertilizing with fresh stool(χ^(2)=28.354,P<0.001).Furthermore,the southern region demonstrated the highest temperature and rainfall level and the lowest GNP and annual net income per capita(all P<0.05).Conclusions There is a remarkable declining in STHs prevalence in Shandong Province from 2016 to 2020.However,the prevalence rates of STHs especially T.trichiura in the southern and eastern regions were still high,and the elderly were more susceptible to be infected with STHs owning to their low awareness level of STHS-related prevention knowledge and high adoption rate of dangerous production and living behaviours.Integrated approaches of health education,environment improvement and behaviour change should be strengthened to obtain a further reduction of STHs prevalence in China.展开更多
基金the financial support from the National Natural Science Foundation of China(NSFC-21625604,21878272,91934302 and 21706229)。
文摘Catalytic performance of supported metal catalysts not only depends on the reactivity of metal,but also the adsorption and diffusion properties of gas molecules which are usually affected by many factors,such as temperature,pressure,properties of metal clusters and substrates,etc.To explore the impact of each of these macroscopic factors,we simulated the movement of CO molecules confined in graphene nanoslits with or without supported Pt nanoparticles.The results of molecular dynamics simulations show that the diffusion of gas molecules is accelerated with high temperature,low pressure or low surface-atom number of supported metals.Notably,the supported metal nanoparticles greatly affect the gas diffusion due to the adsorption of gas molecules.Furthermore,to bridge a quantitative relationship between microscopic simulation and macroscopic properties,a generalized formula is derived from the simulation data to calculate the diffusion coefficient.This work helps to advise the diffusion modulation of gas molecules via structural design of catalysts and regulation of reaction conditions.
基金in part supported by BASF Environmental Catalyst and Metal Solutionsthe support of the National Natural Science Foundation of China(Nos.21976117,22125604 and 22276119)the sponsor by“Chenguang Program”supported by Shanghai Education Development Foundation and Shanghai Municipal Education Commission(No.21CGA48)。
文摘Development of hydrothermally stable,low-temperature catalysts for controlling nitrogen oxides emissions from mobile sources remains an urgent challenge.We have prepared a metal oxide-zeolite composite catalyst by depositing Mn active species on a mixture support of CeO_(2)/Al_(2)O_(3) and ZSM-5.This composite catalyst is hydrothermally stable and shows improved low-temperature SCR activity and significantly reduced N_(2)O formation than the corresponding metal oxide catalyst.Comparing with a Cu-CHA catalyst,the composite catalyst has a faster response to NH_(3) injection and less NH_(3) slip.Our characterization results reveal that such an oxide-zeolite composite catalyst contains more acidic sites and Mn^(3+)species as a result of oxide-zeolite interaction,and this interaction leads to the generation of more NH_(4)^(+)species bound to the Br?nsted acid sites and more reactive NOxspecies absorbed on the Mn sites.Herein,we report our mechanistic understanding of the oxide-zeolite composite catalyst and its molecular pathway for improving the low-temperature activity and N_(2) selectivity for NH_(3)-SCR reaction.Practically,this work may provide an alternative methodology for low-temperature NO_(x) control from diesel vehicles.
基金Supported by the Program for Changjiang Scholars,Innovative Research Team in University,NSFC(Nos.51438008 and 21276027)the Natural Science Foundation of Shandong Province,China(No.ZR2015BL031)+2 种基金Higher Educational Science and Technology Program of Shandong Province,China(Nos.J14LC05 and J15LD04)Key Research and Development Plan Project of Shandong Province,China(2015GGX104012)the Natural Science Foundation of Binzhou University,China(No.BZXYG1406)
文摘Hydrous iron oxide and hydrous aluminum oxide were loaded successfully onto a polymeric adsorbent(D301) to modify adsorbing materials(HIOD301 and HAOD301). The adsorptive equilibrium of atrazine was investigated in an aquatic environment using HIOD301 and HAOD301 under different experimental conditions. The results indicated that both HIOD301 and HAOD301 showed good adsorption capacities for atrazine at p H 4. The Langmuir and Freundlich isotherm equations were used to study the interactions between the adsorbate and adsorbent.The adsorption kinetics of atrazine at different concentrations was well described in terms of a pseudosecond-order equation in regard to the correlation coefficients and adsorption capacity. The removal percentages of atrazine for HIOD301 and HAOD301 were still more than 95% in the presence of sodium chloride.
文摘Background Soil-transmitted helminths(STHs)were previously endemic in Shandong Province,China.This study aimed to analyze the STHs prevalence trend and the natural,social,and human cognitive and behavioural factors infuencing the discrepancies between high and low infection levels from 2016 to 2020 in Shandong Province in eastern China.Methods STHs surveillance data of Shandong Province from 2016 to 2020 were obtained from China Information Management System for Prevention and Control of Parasitic Diseases.STHs infections were detected by modifed Kato–Katz method.Comprehensive information on the natural and social factors,STHs-related knowledge and behaviours were collected through questionnaire surveys.Retrospective spatial scan analysis was performed using SaTScan v10.1 to evaluate any identifed spatial clusters of STHs infection for statistical signifcance and Bayes discriminant analysis was used to discriminate the high or low infection groups of the villages.Results In total,72,160 participants were involved in our survey from 2016 to 2020.The overall STHs prevalence rate was 1.13%,with the eastern region of Shandong Province having the highest rate(2.02%).The predominant species was T.trichiura,with the prevalence rate of 0.99%and the≥70-year age group possessed the highest rate of 2.21%.The STHs prevalence rate showed an annual linear downward trend from 2016 to 2020(χ_(trend)^(2) =127.600,P<0.001).Respondents aged≥60 years had the lowest awareness level of STHs-related prevention knowledge(all P<0.05),and were the most likely to adopt the practice of fertilizing with fresh stool(χ^(2)=28.354,P<0.001).Furthermore,the southern region demonstrated the highest temperature and rainfall level and the lowest GNP and annual net income per capita(all P<0.05).Conclusions There is a remarkable declining in STHs prevalence in Shandong Province from 2016 to 2020.However,the prevalence rates of STHs especially T.trichiura in the southern and eastern regions were still high,and the elderly were more susceptible to be infected with STHs owning to their low awareness level of STHS-related prevention knowledge and high adoption rate of dangerous production and living behaviours.Integrated approaches of health education,environment improvement and behaviour change should be strengthened to obtain a further reduction of STHs prevalence in China.
