The discovery of efficient,selective,and stable electrocatalysts can be a key point to produce the largescale chemical fuels via electrochemical CO_(2) reduction(ECR).In this study,an earth-abundant and nontoxic ZnO-b...The discovery of efficient,selective,and stable electrocatalysts can be a key point to produce the largescale chemical fuels via electrochemical CO_(2) reduction(ECR).In this study,an earth-abundant and nontoxic ZnO-based electrocatalyst was developed for use in gas-diffusion electrodes(GDE),and the effect of nitrogen(N)doping on the ECR activity of ZnO electrocatalysts was investigated.Initially,a ZnO nanosheet was prepared via the hydrothermal method,and nitridation was performed at different times to control the N-doping content.With an increase in the N-doping content,the morphological properties of the nanosheet changed significantly,namely,the 2D nanosheets transformed into irregularly shaped nanoparticles.Furthermore,the ECR performance of Zn O electrocatalysts with different N-doping content was assessed in 1.0 M KHCO_(3) electrolyte using a gas-diffusion electrode-based ECR cell.While the ECR activity increased after a small amount of N doping,it decreased for higher N doping content.Among them,the N:ZnO-1 h electrocatalysts showed the best CO selectivity,with a faradaic efficiency(FE_(CO))of 92.7%at-0.73 V vs.reversible hydrogen electrode(RHE),which was greater than that of an undoped Zn O electrocatalyst(FE_(CO)of 63.4%at-0.78 V_(RHE)).Also,the N:ZnO-1 h electrocatalyst exhibited outstanding durability for 16 h,with a partial current density of-92.1 mA cm^(-2).This improvement of N:ZnO-1 h electrocatalyst can be explained by density functional theory calculations,demonstrating that this improvement of N:ZnO-1 h electrocatalyst comes from(ⅰ)the optimized active sites lowering the free energy barrier for the rate-determining step(RDS),and(ⅱ)the modification of electronic structure enhancing the electron transfer rate by N doping.展开更多
One of the primary challenges in relation to phosphoric acid fuel cells is catalyst poisoning by phosphate anions that occurs at the interface between metal nanoparticles and the electrolyte.The strong adsorption of p...One of the primary challenges in relation to phosphoric acid fuel cells is catalyst poisoning by phosphate anions that occurs at the interface between metal nanoparticles and the electrolyte.The strong adsorption of phosphate anions on the catalyst surface limits the active sites for the oxygen reduction reaction(ORR),significantly deteriorating fuel cell performance.Here,antipoisoning catalysts consisting of Pt-based nanoparticles encapsulated in an ultrathin carbon shell that can be used as a molecular sieve layer are rationally designed.The pore structure of the carbon shells is systematically regulated at the atomic level by high-temperature gas treatment,allowing O_(2) molecules to selectively react on the active sites of the metal nanoparticles through the molecular sieves.Besides,the carbon shell,as a protective layer,effectively prevents metal dissolution from the catalyst during a long-term operation.Consequently,the defect-controlled carbon shell leads to outstanding ORR activity and durability of the hybrid catalyst even in phosphoric acid electrolytes.展开更多
The variability in global oceanic evaporation data sets was examined for the period 1988-2000. These data sets are satellite estimates based on bulk aerodynamic formulations and include the NASA/Goddard Space Flight C...The variability in global oceanic evaporation data sets was examined for the period 1988-2000. These data sets are satellite estimates based on bulk aerodynamic formulations and include the NASA/Goddard Space Flight Center Satellite-based Surface Turbulent Flux version 2 （ GSSTF2）, the Japanese-ocean flux using remote sensing observations （J-OFURO）, and the Hamburg Ocean-Atmosphere Parameters and Fluxes from Satellite version 2 （HOAPS2）. The National Center for Environmental Prediction （NCEP） reanalysis is also included for comparison. An increase in global average surface latent heat flux （SLHF） can be observed in all the data sets. Empirical mode decomposition （EMD） shows long-term increases that started around 1990 for all remote sensing data sets. The effect of Mt. Pinatubo eruption in 1991 is clearly evident in HOAPS2 but is independent of the longterm increase. Linear regression analyses show increases of 9.4%, 13.0%, 7. 3%, and 3.9% for GSSTF2, J-OFURO, HOAPS2 and NCEP, for the periods of the data sets. Empirical orthogonal function （EOF） analyses show that the pattern of the first EOF of all data sets is consistent with a decadal variation associated with the enhancement of the tropical Hadley circulation, which is supported by other satellite observations. The second EOF of all four data sets is an ENSO mode, and the correlations between their time series and an SO1 are 0.74, 0.71,0.59, and 0.61 for GSSTF2, J-OFURO, HOAPS2, and NCEP in that order. When the Hadley modes are removed from the remote sensing data, the residue global increases are reduced to 2.2% , 7. 3%, and 〈 1% for GSSTF2, J-OFURO and HOAPS, respectively. If the ENSO mode is used as a calibration standard for the data sets, the Hadley mode is at least comparable to, if not larger than, the ENSO mode during our study period.展开更多
Accurate sea surface flux measurements are crucial for understanding the global water and energy cycles. The oceanic evaporation, which is a major component of the global oceanic fresh water flux, is useful for predic...Accurate sea surface flux measurements are crucial for understanding the global water and energy cycles. The oceanic evaporation, which is a major component of the global oceanic fresh water flux, is useful for predicting oceanic circulation and transport. The global Goddard Satellite-based Surface Turbulent Fluxes Version-2 （GSSTF2; July 1987–December 2000） dateset that was o？cially released in 2001 has been widely used by scientific community for global energy and water cycle research, and regional and short period data analyses. We have recently been funded by NASA to resume processing the GSSTF dataset with an objective of continually producing a uniform dataset of sea surface turbulent fluxes, derived from remote sensing data. The dataset is to be reprocessed and brought up-to-date （GSSTF2b） using improved input datasets such as a recently upgraded NCEP/DOE sea surface temperature reanalysis, and an upgraded surface wind and microwave brightness temperature V6 dataset （Version 6） from the Special Sensor Microwave Imager （SSM/I） produced by Remote Sensing Systems （RSS）. A second new product （GSSTF3） is further proposed with a finer temporal （12-h） and spatial （0.25° × 0.25°） resolution. GSSTF2b （July 1987–December 2008） and GSSTF3 （July 1999–December 2009） will be released for the research community to use by late 2009 and early 2011, respectively.展开更多
European Community policy concerning water is placing increasing demands on the acquisition of information about the quality of aquatic environments. The cost of this information has led to a reflection on the rationa...European Community policy concerning water is placing increasing demands on the acquisition of information about the quality of aquatic environments. The cost of this information has led to a reflection on the rationalization of monitoring networks and, therefore, on the economic value of information produced by these networks. The aim of this article is to contribute to this reflection. To do so, we used the Bayesian framework to define the value of additional information in relation to the following three parameters: initial assumptions (prior probabilities) on the states of nature, costs linked to a poor decision (error costs) and accuracy of additional information. We then analyzed the impact of these parameters on this value, particularly the combined role of prior probabilities and error costs that increased or decreased the value of information depending on the initial uncertainty level. We then illustrated the results using a case study of a stream in the Bas-Rhin department in France.展开更多
Aim: To evaluate data related to mental work functioning of workers with cancer diagnosis in radiotherapy in a private service in the city of Campinas, State of São Paulo, Brazil. Method: It consists in a c...Aim: To evaluate data related to mental work functioning of workers with cancer diagnosis in radiotherapy in a private service in the city of Campinas, State of São Paulo, Brazil. Method: It consists in a cross-sectional, observational and analytical study with comparison between cancer patients and healthy people, using the Brazilian version of the Work Role Functioning Questionnaire (WRFQ-Br). Descriptive and statistical analysis is performed by the Mann-Whitney test. Results: There was a significant difference between the groups in the evaluation of mental demand;however, the population diagnosed with malignant neoplasm submitted to radiotherapy had unexpected higher scores, reflecting lower mental exigency. Conclusions: The observed context may occur due to extensive support of family, government and interdisciplinary team of health care for individuals diagnosed with cancer. This data provide support for new research studies related to the importance of the work to promote mental health, considering aspects related to social interaction and productivity as the support system members. The importance of disseminating these results and limitation is based in the necessity of investments to improve research and actions to promote the permanence and early return to work for cancer survivors in Brazil and Latin America.展开更多
A process to convert models made by rapid prototypi ng techniques like SL(stereolitography)and LOM(laminated object manufacturing)or by conventional techniques(silicones,resins,wax,etc.)into metallic mould s or tools ...A process to convert models made by rapid prototypi ng techniques like SL(stereolitography)and LOM(laminated object manufacturing)or by conventional techniques(silicones,resins,wax,etc.)into metallic mould s or tools has been developed.The main purpose of this technique is to rapidly obtain the first prototypes of parts,for plastics injection,forging or any oth er manufacturing process using the tools produced by casting a metal into a cera mic mould.Briefly,it can be said that the ceramic moulds are produced by mixing in variab le proportions,depending on the type of ceramics employed,strength and roughne ss desired,a ceramic mixture composed by alumina and/or zirconium silicates bon ded with silica coming from a liquid binder,based on ethyl silicate.A catalyst is added to the slurry in order to produce a sol-gel reaction.The liquid slur ry is poured into the box containing the mould to be reproduced.After a short p eriod of time,controlled by the amount of gelling agent,the ceramic mixture ac quires a rubber consistency.The pattern is removed from the ceramic mould,whic h is fired to stop the gelation reaction.After this stabilization the ceramic m ould is sintered at high temperatures in order to generate an inert mould wi th the desired strength in which almost all metallic alloys can be cast.The effect of ceramic materials(shape,granulometric distribution,chemical com position,etc.),processing parameters(proportion binder/ceramic/catalyst,sint ering conditions,etc.)and casting conditions(mould pre-heating temperature a nd pouring temperature)were studied in order to obtain metallic moulds or tools with tailored properties(high dimensional accuracy,low roughness and high mec hanical strength).展开更多
Nanomaterials integrated surface acoustic wave(SAW)gas sensing technology has emerged as a promising candidate for realtime toxic gas sensing applications for environmental and human health safety.However,the developm...Nanomaterials integrated surface acoustic wave(SAW)gas sensing technology has emerged as a promising candidate for realtime toxic gas sensing applications for environmental and human health safety.However,the development of novel chemical interface based on two-dimensional(2D)sensing materials for SAW sensors for the rapid and sensitive detection of NH_(3)gas at room temperature(RT)still remains challenging.Herein,we report a highly selective RT NH_(3)gas sensor based on sulfur-doped graphitic carbon nitride quantum dots(S@g-C_(3)N_(4)QD)coated langasite(LGS)SAW sensor with enhanced sensitivity and recovery rate under ultraviolet(UV)illumination.Fascinatingly,the sensitivity of the S@g-C_(3)N_(4)QD/LGS SAW sensor to NH_(3)(500 ppb)at RT is dramatically enhanced by~4.5-fold with a low detection limit(~85 ppb),high selectivity,excellent reproducibility,fast response/recovery time(70 s/79 s)under UV activation(365 nm)as compared to dark condition.Additionally,the proposed sensor exhibited augmented NH_(3)detection capability across the broad range of relative humidity(20%–80%).Such remarkable gas sensing performances of the as-prepared sensor to NH_(3)are attributed to the high surface area,enhanced functional groups,sulfur defects,UV photogenerated charge carriers,facile charge transfer in the S@g-C_(3)N_(4)QD sensing layer,which further helps to improve the gas molecules adsorption that causes the increase in conductivity,resulting in larger frequency responses.The gas sensing mechanism of S@g-C_(3)N_(4)QD/LGS SAW sensor is ascribed to the enhanced electroacoustic effect,which is supported by the correlation of resistive type and COMSOL Multiphysics simulation studies.We envisage that the present work paves a promising strategy to develop the next generation 2D g-C_(3)N_(4)based high responsive RT SAW gas sensors.展开更多
基金supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF) (Grant Nos.2018R1A6A1A03024334,2019R1A2C1007637,2021M3I3A1082880,2021R1I1A1A01044174)the Basic Science Research Capacity Enhancement Project through Korea Basic Science Institute (Grant No.2019R1A6C1010024)。
文摘The discovery of efficient,selective,and stable electrocatalysts can be a key point to produce the largescale chemical fuels via electrochemical CO_(2) reduction(ECR).In this study,an earth-abundant and nontoxic ZnO-based electrocatalyst was developed for use in gas-diffusion electrodes(GDE),and the effect of nitrogen(N)doping on the ECR activity of ZnO electrocatalysts was investigated.Initially,a ZnO nanosheet was prepared via the hydrothermal method,and nitridation was performed at different times to control the N-doping content.With an increase in the N-doping content,the morphological properties of the nanosheet changed significantly,namely,the 2D nanosheets transformed into irregularly shaped nanoparticles.Furthermore,the ECR performance of Zn O electrocatalysts with different N-doping content was assessed in 1.0 M KHCO_(3) electrolyte using a gas-diffusion electrode-based ECR cell.While the ECR activity increased after a small amount of N doping,it decreased for higher N doping content.Among them,the N:ZnO-1 h electrocatalysts showed the best CO selectivity,with a faradaic efficiency(FE_(CO))of 92.7%at-0.73 V vs.reversible hydrogen electrode(RHE),which was greater than that of an undoped Zn O electrocatalyst(FE_(CO)of 63.4%at-0.78 V_(RHE)).Also,the N:ZnO-1 h electrocatalyst exhibited outstanding durability for 16 h,with a partial current density of-92.1 mA cm^(-2).This improvement of N:ZnO-1 h electrocatalyst can be explained by density functional theory calculations,demonstrating that this improvement of N:ZnO-1 h electrocatalyst comes from(ⅰ)the optimized active sites lowering the free energy barrier for the rate-determining step(RDS),and(ⅱ)the modification of electronic structure enhancing the electron transfer rate by N doping.
基金National Research Foundation of Korea(NRF),Grant/Award Number:2021R1A2C2012685Korea Institute of Energy Technology Evaluation and Planning(KETEP),Grant/Award Number:20203020030010Ministry of Trade,Industry&Energy(MOTIE,Korea),Grant/Award Number:20020400。
文摘One of the primary challenges in relation to phosphoric acid fuel cells is catalyst poisoning by phosphate anions that occurs at the interface between metal nanoparticles and the electrolyte.The strong adsorption of phosphate anions on the catalyst surface limits the active sites for the oxygen reduction reaction(ORR),significantly deteriorating fuel cell performance.Here,antipoisoning catalysts consisting of Pt-based nanoparticles encapsulated in an ultrathin carbon shell that can be used as a molecular sieve layer are rationally designed.The pore structure of the carbon shells is systematically regulated at the atomic level by high-temperature gas treatment,allowing O_(2) molecules to selectively react on the active sites of the metal nanoparticles through the molecular sieves.Besides,the carbon shell,as a protective layer,effectively prevents metal dissolution from the catalyst during a long-term operation.Consequently,the defect-controlled carbon shell leads to outstanding ORR activity and durability of the hybrid catalyst even in phosphoric acid electrolytes.
文摘The variability in global oceanic evaporation data sets was examined for the period 1988-2000. These data sets are satellite estimates based on bulk aerodynamic formulations and include the NASA/Goddard Space Flight Center Satellite-based Surface Turbulent Flux version 2 （ GSSTF2）, the Japanese-ocean flux using remote sensing observations （J-OFURO）, and the Hamburg Ocean-Atmosphere Parameters and Fluxes from Satellite version 2 （HOAPS2）. The National Center for Environmental Prediction （NCEP） reanalysis is also included for comparison. An increase in global average surface latent heat flux （SLHF） can be observed in all the data sets. Empirical mode decomposition （EMD） shows long-term increases that started around 1990 for all remote sensing data sets. The effect of Mt. Pinatubo eruption in 1991 is clearly evident in HOAPS2 but is independent of the longterm increase. Linear regression analyses show increases of 9.4%, 13.0%, 7. 3%, and 3.9% for GSSTF2, J-OFURO, HOAPS2 and NCEP, for the periods of the data sets. Empirical orthogonal function （EOF） analyses show that the pattern of the first EOF of all data sets is consistent with a decadal variation associated with the enhancement of the tropical Hadley circulation, which is supported by other satellite observations. The second EOF of all four data sets is an ENSO mode, and the correlations between their time series and an SO1 are 0.74, 0.71,0.59, and 0.61 for GSSTF2, J-OFURO, HOAPS2, and NCEP in that order. When the Hadley modes are removed from the remote sensing data, the residue global increases are reduced to 2.2% , 7. 3%, and 〈 1% for GSSTF2, J-OFURO and HOAPS, respectively. If the ENSO mode is used as a calibration standard for the data sets, the Hadley mode is at least comparable to, if not larger than, the ENSO mode during our study period.
基金supported by the Making Earth System data records for Use in Research En-vironments (MEaSUREs) Program of NASA Science Mission Directorate-Earth Science Division
文摘Accurate sea surface flux measurements are crucial for understanding the global water and energy cycles. The oceanic evaporation, which is a major component of the global oceanic fresh water flux, is useful for predicting oceanic circulation and transport. The global Goddard Satellite-based Surface Turbulent Fluxes Version-2 （GSSTF2; July 1987–December 2000） dateset that was o？cially released in 2001 has been widely used by scientific community for global energy and water cycle research, and regional and short period data analyses. We have recently been funded by NASA to resume processing the GSSTF dataset with an objective of continually producing a uniform dataset of sea surface turbulent fluxes, derived from remote sensing data. The dataset is to be reprocessed and brought up-to-date （GSSTF2b） using improved input datasets such as a recently upgraded NCEP/DOE sea surface temperature reanalysis, and an upgraded surface wind and microwave brightness temperature V6 dataset （Version 6） from the Special Sensor Microwave Imager （SSM/I） produced by Remote Sensing Systems （RSS）. A second new product （GSSTF3） is further proposed with a finer temporal （12-h） and spatial （0.25° × 0.25°） resolution. GSSTF2b （July 1987–December 2008） and GSSTF3 （July 1999–December 2009） will be released for the research community to use by late 2009 and early 2011, respectively.
文摘European Community policy concerning water is placing increasing demands on the acquisition of information about the quality of aquatic environments. The cost of this information has led to a reflection on the rationalization of monitoring networks and, therefore, on the economic value of information produced by these networks. The aim of this article is to contribute to this reflection. To do so, we used the Bayesian framework to define the value of additional information in relation to the following three parameters: initial assumptions (prior probabilities) on the states of nature, costs linked to a poor decision (error costs) and accuracy of additional information. We then analyzed the impact of these parameters on this value, particularly the combined role of prior probabilities and error costs that increased or decreased the value of information depending on the initial uncertainty level. We then illustrated the results using a case study of a stream in the Bas-Rhin department in France.
文摘Aim: To evaluate data related to mental work functioning of workers with cancer diagnosis in radiotherapy in a private service in the city of Campinas, State of São Paulo, Brazil. Method: It consists in a cross-sectional, observational and analytical study with comparison between cancer patients and healthy people, using the Brazilian version of the Work Role Functioning Questionnaire (WRFQ-Br). Descriptive and statistical analysis is performed by the Mann-Whitney test. Results: There was a significant difference between the groups in the evaluation of mental demand;however, the population diagnosed with malignant neoplasm submitted to radiotherapy had unexpected higher scores, reflecting lower mental exigency. Conclusions: The observed context may occur due to extensive support of family, government and interdisciplinary team of health care for individuals diagnosed with cancer. This data provide support for new research studies related to the importance of the work to promote mental health, considering aspects related to social interaction and productivity as the support system members. The importance of disseminating these results and limitation is based in the necessity of investments to improve research and actions to promote the permanence and early return to work for cancer survivors in Brazil and Latin America.
基金Teresa P DUARTE,Email:tpd@fe.up.ptF Jorge LINO,falves@fe.up.ptA BARBEDO,barbedo@fe.up.pt
文摘A process to convert models made by rapid prototypi ng techniques like SL(stereolitography)and LOM(laminated object manufacturing)or by conventional techniques(silicones,resins,wax,etc.)into metallic mould s or tools has been developed.The main purpose of this technique is to rapidly obtain the first prototypes of parts,for plastics injection,forging or any oth er manufacturing process using the tools produced by casting a metal into a cera mic mould.Briefly,it can be said that the ceramic moulds are produced by mixing in variab le proportions,depending on the type of ceramics employed,strength and roughne ss desired,a ceramic mixture composed by alumina and/or zirconium silicates bon ded with silica coming from a liquid binder,based on ethyl silicate.A catalyst is added to the slurry in order to produce a sol-gel reaction.The liquid slur ry is poured into the box containing the mould to be reproduced.After a short p eriod of time,controlled by the amount of gelling agent,the ceramic mixture ac quires a rubber consistency.The pattern is removed from the ceramic mould,whic h is fired to stop the gelation reaction.After this stabilization the ceramic m ould is sintered at high temperatures in order to generate an inert mould wi th the desired strength in which almost all metallic alloys can be cast.The effect of ceramic materials(shape,granulometric distribution,chemical com position,etc.),processing parameters(proportion binder/ceramic/catalyst,sint ering conditions,etc.)and casting conditions(mould pre-heating temperature a nd pouring temperature)were studied in order to obtain metallic moulds or tools with tailored properties(high dimensional accuracy,low roughness and high mec hanical strength).
基金the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.2020R1A2C2013385)Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(No.NRF-2020R1A6A1A03047771)Korea Institute of Planning and Evaluation for Technology in Food,Agriculture and Forestry(IPET),Korea Smart Farm Research and Development Foundation(KosFarm)through Smart Farm Innovation Technology Development Program,funded by Ministry of Agriculture,Food,and Rural Affairs(MAFRA)and Ministry of Science and ICT(MSIT),Rural Development Administration(RDA)(No.421029-4).
文摘Nanomaterials integrated surface acoustic wave(SAW)gas sensing technology has emerged as a promising candidate for realtime toxic gas sensing applications for environmental and human health safety.However,the development of novel chemical interface based on two-dimensional(2D)sensing materials for SAW sensors for the rapid and sensitive detection of NH_(3)gas at room temperature(RT)still remains challenging.Herein,we report a highly selective RT NH_(3)gas sensor based on sulfur-doped graphitic carbon nitride quantum dots(S@g-C_(3)N_(4)QD)coated langasite(LGS)SAW sensor with enhanced sensitivity and recovery rate under ultraviolet(UV)illumination.Fascinatingly,the sensitivity of the S@g-C_(3)N_(4)QD/LGS SAW sensor to NH_(3)(500 ppb)at RT is dramatically enhanced by~4.5-fold with a low detection limit(~85 ppb),high selectivity,excellent reproducibility,fast response/recovery time(70 s/79 s)under UV activation(365 nm)as compared to dark condition.Additionally,the proposed sensor exhibited augmented NH_(3)detection capability across the broad range of relative humidity(20%–80%).Such remarkable gas sensing performances of the as-prepared sensor to NH_(3)are attributed to the high surface area,enhanced functional groups,sulfur defects,UV photogenerated charge carriers,facile charge transfer in the S@g-C_(3)N_(4)QD sensing layer,which further helps to improve the gas molecules adsorption that causes the increase in conductivity,resulting in larger frequency responses.The gas sensing mechanism of S@g-C_(3)N_(4)QD/LGS SAW sensor is ascribed to the enhanced electroacoustic effect,which is supported by the correlation of resistive type and COMSOL Multiphysics simulation studies.We envisage that the present work paves a promising strategy to develop the next generation 2D g-C_(3)N_(4)based high responsive RT SAW gas sensors.
