Urban growth has promoted the use of underground spaces,where explosion accidents can be catastrophic.In this study,we investigated the effect of placing flexible construction in front of rigid obstacles on methane ex...Urban growth has promoted the use of underground spaces,where explosion accidents can be catastrophic.In this study,we investigated the effect of placing flexible construction in front of rigid obstacles on methane explosion protection by using an experimental platform and adjusting the blockage rate and spacing of the obstacles.It aims to reduce the risk of gas explosions in urban underground spaces.The results of the study show that the flame propagation peak speed and peak overpressure are reduced with the decrease in the blocking rate of the flexible obstacle when the blocking rate of the flexible obstacle is less than or equal to the blocking rate of the rigid obstacle,with the decrease in the spacing,the better the protection effect of the methane explosion.When the blockage rate of the flexible obstacle is greater than the blockage rate of the rigid obstacle and spacing is less than the height of the flexible obstacle,rigid and flexible obstacles are connected as a whole,increasing the strength of the explosion.This study can provide a theoretical basis and scientific guidance for optimizing rigid and flexible object hybrid layouts and methane explosion protection technology in urban underground spaces.展开更多
Single-atom catalysis,the catalysis by single-atom catalysts(SACs),has attracted considerable attention in recent years as a new frontier in the heterogeneous catalysis field.SACs have the advantages of both homogeneo...Single-atom catalysis,the catalysis by single-atom catalysts(SACs),has attracted considerable attention in recent years as a new frontier in the heterogeneous catalysis field.SACs have the advantages of both homogeneous catalysts(isolated active sites)and heterogeneous catalysts(stable and easy to separate),and are thus predicted to be able to bridge the homo-and heterogeneous catalysis.This prediction was first experimentally demonstrated in 2016.In this mini-review,we summarize the few homogeneous catalysis progresses reported recently where SACs have exhibited promising application:a)Rh/ZnO and Rh/CoO SAC have been used successfully in hydroformylation of olefin of which the activity are comparable to the homogeneous Wilkinson’s catalyst;b)a Pt/Al2O3 SAC has shown excellent performance in hydrosilylation reaction;and c)M-N-C SACs(M=Fe,Co etc.)have been applied in the activation of C–H bonds.All of these examples suggest that fabrication of suitable SACs could provide a new avenue for the heterogenization of homogeneous catalysts.These pioneering works shed new light on the recognition of single-atom catalysis in bridging the homo-and heterogeneous catalysis.展开更多
CO oxidation is of great importance in both fundamental study and industrial application.Supported noble metal catalysts are highly active for CO oxidation but suffer from the scarcity and high cost.Single-atom cataly...CO oxidation is of great importance in both fundamental study and industrial application.Supported noble metal catalysts are highly active for CO oxidation but suffer from the scarcity and high cost.Single-atom catalysts(SACs)can maximize the metal atom efficiency.Herein,ZnO nanowire(ZnO-nw)supported Rh,Au,and Pt SACs were successfully developed to investigate their CO oxidation performance.Interestingly,it was found that Rh1/ZnO-nw showed much higher activity than the other noble metals which are usually regarded as good candidates for CO oxidation.In addition,the Rh SAC possessed high stability in high-temperature CO oxidation under simulated conditions in the presence of water and hydrocarbons.The high activity and stability make Rh1/ZnO-nw promising for practical applications,especially in the automotive exhaust emission control.Theoretical calculations indicate that the CO oxidation proceeds via the Mars-van Krevelen mechanism and the lowest barrier for the rate-limiting O2 dissociation at a surface oxygen vacancy site is a key factor in determining the observed highest activity of Rh1/ZnO-nw amongst the studied SACs.展开更多
The idea that single metal atoms dispersed on a solid support can act as an efficient heterogeneous catalyst was raised in2011when single Pt atoms on an FeOx surface were reported to be active for CO oxidation and pre...The idea that single metal atoms dispersed on a solid support can act as an efficient heterogeneous catalyst was raised in2011when single Pt atoms on an FeOx surface were reported to be active for CO oxidation and preferential oxidation of CO in H2.The last six years have witnessed tremendous progress in the field of single‐atom catalysis.Here we introduce the major achievements on this topic in2015and2016.Some particular aspects of single‐atom catalysis are discussed in depth,including new approaches in single‐atom catalyst(SAC)synthesis,stable gold SACs for various reactions,the high selectivity of Pt and Pd SACs in hydrogenation,and the superior performance of non‐noble metal SACs in electrochemistry.These accomplishments will encourage more efforts by researchers to achieve the controllable fabrication of SACs and explore their potential applications.展开更多
With the enrollment expansion of college and continuous reform of college education system and college charging system,the number of college students with financial difficulties is increasing. The college students wit...With the enrollment expansion of college and continuous reform of college education system and college charging system,the number of college students with financial difficulties is increasing. The college students with family financial difficulties not only bear the huge economic burden,but also bear the huge pressure of learning and mental stress,and they have many kinds of psychological problems including psychological distress of tension and anxiety,psychological conflict of self-respect and self-abasement,conflict of desire for interpersonal interaction and self-containment and strong vanity and dependence mentality. This paper puts forward the corresponding recommendations to solve these problems.展开更多
Background:The incidence of idiopathic nlembranous nephropathy(IMN)has recently increased remarkably.Immune dysfunction caused by disordered intestinal flora might be an important factor affecting IMN.The Jian Pi Qu S...Background:The incidence of idiopathic nlembranous nephropathy(IMN)has recently increased remarkably.Immune dysfunction caused by disordered intestinal flora might be an important factor affecting IMN.The Jian Pi Qu Shi Formula(JPQSF)shows promise in treating IMN.Here,we sequenced 16S rRNA genes to compare intestinal flora between patients with IMN and healthy persons.We also conducted a randomized controlled clinical trial to further compare the intestinal flora of patients with IMN treated with traditional Chinese medicine(TCM)and western medicine(WM).Methods:Among 40 patie nls with IMN treated at Department of Nephrology in Xiyuan Hospital,Chinese Academy of Traditional Chinese Medicine between July 2016 and December 2018,we compared 30 of them with 10 healthy persons(controls).The IMN group was randomly assigned to receive JPQSF(TCM)or immunosuppressant WM therapy in(n=15 per group)for 6 months.Intestinal microbiota diversity was analyzed using alpha diversity and beta diversity.Intestinal flora that significantly differed between the groups was analyzed using MetaStat.The effects and safety of the therapies were determined based on the values for plasma albumin,24-h urine protein excretion,serum creatinine,urea nitrogen,estimate glomerular filtration rate(eGFR),complete blood count,and liver enzymes.All data were statistically analyzed using Statistical Package for the Social Sciences(SPSS)20.0 statistical software.Results:Baseline characteristics did not significanlly differ between the IMN and healthy groups,or the TCM and WM groups.After six months of treatment,24-h urinary protein significantly declined in the TCM and WM groups(before and after treatment:3.24±1.74 vs.1.73±1.85 g,P<0.05 and 3.94±1.05 vs.1.91±1.18 g,P<0.05,respectively).Plasma albumin was significantly increased in the TCM group(before vs.after treatment:32.44±9.04 vs.39.99±7.03 g/L,P<0.05),but did not significantly change in the WM group(31.55±4.23 vs.34.83±9」4 g/L,P>0.05).Values for urea nitrogen,serum creatinine,and eGFR did not significanlly change in either group.The alpha diversity index for intestinal flora differed between the IMN and healthy groups,and the TCM and WM groups.Comparisons of multiple samples(beta diversity)revealed differences in intestinal flora between the IMN and healthy groups,and the TCM and WM groups.The Metastat analysis findings showed that the main genera that differed between the IMN group before treatment and the healthy group were Christensenellaceae_R-7_group,Bifidobacterium(77),Dorea,Escherichia-Shigella,Parabacteroides,Bifidobacterium,and Coprococcus_3.AfterTCM therapy,the main differential genera were Butyricimonas,Bacteroides,Alistipes,and Lachnospira,and after WM therapy,these were Ruminococcus_2,Lachnospiraceae_ND3007_group,Lachnospira,Bifidobacterium,Alistipes,and[Eubacterium]_ventriosum_group.Conclusion:Patients with IMN might have disordered intestinal flora,and JPQSF can regulate intestinal flora in patienls with IMN.展开更多
Alcohol-based disinfectants have protected people in the coronavirus disease 2019(COVID-19)pandemic,but olfactory stimuli of ethanol may evoke unpleasant memories associated with stressful situations in the devastatin...Alcohol-based disinfectants have protected people in the coronavirus disease 2019(COVID-19)pandemic,but olfactory stimuli of ethanol may evoke unpleasant memories associated with stressful situations in the devastating infectious disease.The smell of ethanol in household cleaning and disinfectant products can be covered up by the fragrance additives,and 3-hexenol is especially appreciated for the characteristic,strong odor of green plants.Industrial production of 3-hexenol relies on the selective hydrogenation of 3-hexyn-1-ol,where Lindlar catalyst is normally used for the superior selectivity.Although achieving such catalytic transformation in ethanol solution seems as a direct way to produce a disinfectant with green aroma,a popular consumer product in the post-COVID era,severe leaching of toxic Pb hinders Lindlar catalyst as a promising candidate.We find that the Fe_(2)O_(3) supported Pd single-atom catalyst is highly selective to fulfill semi-hydrogenation of 3-hexyn-1-ol in 75%ethanol,and the aforementioned household product is readily generated after filtrating the stable,solid catalyst out of reaction solution.Single-atom catalysts have been frequently utilized for fine-chemical synthesis,while in this work they make stunning debut in practical manufacture of daily used products.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.52274177)Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJZD-K202401501)+1 种基金Chongqing Graduate Student Research Innovation Program(Grant No.CYS240800)The Science and Technology Innovation Project for Graduate Students of Chongqing University of Science and Technology(Grant No.YKJCX2420702).
文摘Urban growth has promoted the use of underground spaces,where explosion accidents can be catastrophic.In this study,we investigated the effect of placing flexible construction in front of rigid obstacles on methane explosion protection by using an experimental platform and adjusting the blockage rate and spacing of the obstacles.It aims to reduce the risk of gas explosions in urban underground spaces.The results of the study show that the flame propagation peak speed and peak overpressure are reduced with the decrease in the blocking rate of the flexible obstacle when the blocking rate of the flexible obstacle is less than or equal to the blocking rate of the rigid obstacle,with the decrease in the spacing,the better the protection effect of the methane explosion.When the blockage rate of the flexible obstacle is greater than the blockage rate of the rigid obstacle and spacing is less than the height of the flexible obstacle,rigid and flexible obstacles are connected as a whole,increasing the strength of the explosion.This study can provide a theoretical basis and scientific guidance for optimizing rigid and flexible object hybrid layouts and methane explosion protection technology in urban underground spaces.
基金supported by National Natural Science Foundation of China(21606222,21776270)Postdoctoral Science Foundation(2017M621170,2016M601350)~~
文摘Single-atom catalysis,the catalysis by single-atom catalysts(SACs),has attracted considerable attention in recent years as a new frontier in the heterogeneous catalysis field.SACs have the advantages of both homogeneous catalysts(isolated active sites)and heterogeneous catalysts(stable and easy to separate),and are thus predicted to be able to bridge the homo-and heterogeneous catalysis.This prediction was first experimentally demonstrated in 2016.In this mini-review,we summarize the few homogeneous catalysis progresses reported recently where SACs have exhibited promising application:a)Rh/ZnO and Rh/CoO SAC have been used successfully in hydroformylation of olefin of which the activity are comparable to the homogeneous Wilkinson’s catalyst;b)a Pt/Al2O3 SAC has shown excellent performance in hydrosilylation reaction;and c)M-N-C SACs(M=Fe,Co etc.)have been applied in the activation of C–H bonds.All of these examples suggest that fabrication of suitable SACs could provide a new avenue for the heterogenization of homogeneous catalysts.These pioneering works shed new light on the recognition of single-atom catalysis in bridging the homo-and heterogeneous catalysis.
基金supported by the National Natural Science Foundation of China(21606222,21776270)Liaoning Revitalization Talents Program(XLYC1807068)+1 种基金DNL Cooperation Fund,CAS(180403)US National Science Foundation under CHE-1465057~~
文摘CO oxidation is of great importance in both fundamental study and industrial application.Supported noble metal catalysts are highly active for CO oxidation but suffer from the scarcity and high cost.Single-atom catalysts(SACs)can maximize the metal atom efficiency.Herein,ZnO nanowire(ZnO-nw)supported Rh,Au,and Pt SACs were successfully developed to investigate their CO oxidation performance.Interestingly,it was found that Rh1/ZnO-nw showed much higher activity than the other noble metals which are usually regarded as good candidates for CO oxidation.In addition,the Rh SAC possessed high stability in high-temperature CO oxidation under simulated conditions in the presence of water and hydrocarbons.The high activity and stability make Rh1/ZnO-nw promising for practical applications,especially in the automotive exhaust emission control.Theoretical calculations indicate that the CO oxidation proceeds via the Mars-van Krevelen mechanism and the lowest barrier for the rate-limiting O2 dissociation at a surface oxygen vacancy site is a key factor in determining the observed highest activity of Rh1/ZnO-nw amongst the studied SACs.
基金supported by the National Natural Science Foundation of China(21606222,21303184,21573232)China Postdoctoral Science Foundation(2016M601350)+2 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(XDB17020100)National Key Projects for Fundamental Research and Development of China(2016YFA0202801)Department of Science and Technology of Liaoning Province(2015020086-101)~~
文摘The idea that single metal atoms dispersed on a solid support can act as an efficient heterogeneous catalyst was raised in2011when single Pt atoms on an FeOx surface were reported to be active for CO oxidation and preferential oxidation of CO in H2.The last six years have witnessed tremendous progress in the field of single‐atom catalysis.Here we introduce the major achievements on this topic in2015and2016.Some particular aspects of single‐atom catalysis are discussed in depth,including new approaches in single‐atom catalyst(SAC)synthesis,stable gold SACs for various reactions,the high selectivity of Pt and Pd SACs in hydrogenation,and the superior performance of non‐noble metal SACs in electrochemistry.These accomplishments will encourage more efforts by researchers to achieve the controllable fabrication of SACs and explore their potential applications.
基金Supported by Basic Scientific Research Project on Ideological and Political Theory in Northwest Forestry and Forestry University in 2017(2017RWSZ01)Fine Student Project in Northwest Forestry and Forestry University in 2016(2016JP002)
文摘With the enrollment expansion of college and continuous reform of college education system and college charging system,the number of college students with financial difficulties is increasing. The college students with family financial difficulties not only bear the huge economic burden,but also bear the huge pressure of learning and mental stress,and they have many kinds of psychological problems including psychological distress of tension and anxiety,psychological conflict of self-respect and self-abasement,conflict of desire for interpersonal interaction and self-containment and strong vanity and dependence mentality. This paper puts forward the corresponding recommendations to solve these problems.
基金This study was supported by grants from the National Key R&D Plan of China(No.2019 YFC1708500)the National Natural Science Foundation of China(No.81374036)the Natural Science Foun dation of Wan nan Medical College under Grant(No.WYRCQD2018009).
文摘Background:The incidence of idiopathic nlembranous nephropathy(IMN)has recently increased remarkably.Immune dysfunction caused by disordered intestinal flora might be an important factor affecting IMN.The Jian Pi Qu Shi Formula(JPQSF)shows promise in treating IMN.Here,we sequenced 16S rRNA genes to compare intestinal flora between patients with IMN and healthy persons.We also conducted a randomized controlled clinical trial to further compare the intestinal flora of patients with IMN treated with traditional Chinese medicine(TCM)and western medicine(WM).Methods:Among 40 patie nls with IMN treated at Department of Nephrology in Xiyuan Hospital,Chinese Academy of Traditional Chinese Medicine between July 2016 and December 2018,we compared 30 of them with 10 healthy persons(controls).The IMN group was randomly assigned to receive JPQSF(TCM)or immunosuppressant WM therapy in(n=15 per group)for 6 months.Intestinal microbiota diversity was analyzed using alpha diversity and beta diversity.Intestinal flora that significantly differed between the groups was analyzed using MetaStat.The effects and safety of the therapies were determined based on the values for plasma albumin,24-h urine protein excretion,serum creatinine,urea nitrogen,estimate glomerular filtration rate(eGFR),complete blood count,and liver enzymes.All data were statistically analyzed using Statistical Package for the Social Sciences(SPSS)20.0 statistical software.Results:Baseline characteristics did not significanlly differ between the IMN and healthy groups,or the TCM and WM groups.After six months of treatment,24-h urinary protein significantly declined in the TCM and WM groups(before and after treatment:3.24±1.74 vs.1.73±1.85 g,P<0.05 and 3.94±1.05 vs.1.91±1.18 g,P<0.05,respectively).Plasma albumin was significantly increased in the TCM group(before vs.after treatment:32.44±9.04 vs.39.99±7.03 g/L,P<0.05),but did not significantly change in the WM group(31.55±4.23 vs.34.83±9」4 g/L,P>0.05).Values for urea nitrogen,serum creatinine,and eGFR did not significanlly change in either group.The alpha diversity index for intestinal flora differed between the IMN and healthy groups,and the TCM and WM groups.Comparisons of multiple samples(beta diversity)revealed differences in intestinal flora between the IMN and healthy groups,and the TCM and WM groups.The Metastat analysis findings showed that the main genera that differed between the IMN group before treatment and the healthy group were Christensenellaceae_R-7_group,Bifidobacterium(77),Dorea,Escherichia-Shigella,Parabacteroides,Bifidobacterium,and Coprococcus_3.AfterTCM therapy,the main differential genera were Butyricimonas,Bacteroides,Alistipes,and Lachnospira,and after WM therapy,these were Ruminococcus_2,Lachnospiraceae_ND3007_group,Lachnospira,Bifidobacterium,Alistipes,and[Eubacterium]_ventriosum_group.Conclusion:Patients with IMN might have disordered intestinal flora,and JPQSF can regulate intestinal flora in patienls with IMN.
基金supported by the National Natural Science Foundation of China(Nos.22378079,22102210)Guangzhou Projects for Fundamental Research(No.202102020202)+1 种基金the Guangdong Provincial Key Laboratory of Plant Resources Biorefinery(No.2021GDKLPRB10)the start-up funding of Guangdong University of Technology.
文摘Alcohol-based disinfectants have protected people in the coronavirus disease 2019(COVID-19)pandemic,but olfactory stimuli of ethanol may evoke unpleasant memories associated with stressful situations in the devastating infectious disease.The smell of ethanol in household cleaning and disinfectant products can be covered up by the fragrance additives,and 3-hexenol is especially appreciated for the characteristic,strong odor of green plants.Industrial production of 3-hexenol relies on the selective hydrogenation of 3-hexyn-1-ol,where Lindlar catalyst is normally used for the superior selectivity.Although achieving such catalytic transformation in ethanol solution seems as a direct way to produce a disinfectant with green aroma,a popular consumer product in the post-COVID era,severe leaching of toxic Pb hinders Lindlar catalyst as a promising candidate.We find that the Fe_(2)O_(3) supported Pd single-atom catalyst is highly selective to fulfill semi-hydrogenation of 3-hexyn-1-ol in 75%ethanol,and the aforementioned household product is readily generated after filtrating the stable,solid catalyst out of reaction solution.Single-atom catalysts have been frequently utilized for fine-chemical synthesis,while in this work they make stunning debut in practical manufacture of daily used products.
