Unraveling the essence of electronic structure effected by d-d orbital coupling of transition metal and methanol oxidation reaction(MOR)performance can fundamentally guide high efficient catalyst design.Herein,density...Unraveling the essence of electronic structure effected by d-d orbital coupling of transition metal and methanol oxidation reaction(MOR)performance can fundamentally guide high efficient catalyst design.Herein,density functional theory(DFT)calculations were performed at first to study the d–d orbital interaction of metallic Pt Pd Cu,revealing that the incorporation of Pd and Cu atoms into Pt system can enhance d-d electron interaction via capturing antibonding orbital electrons of Pt to fill the surrounding Pd and Cu atoms.Under the theoretical guidance,Pt Pd Cu medium entropy alloy aerogels(Pt Pd Cu MEAAs)catalysts have been designed and systematically screened for MOR under acid,alkaline and neutral electrolyte.Furthermore,DFT calculation and in-situ fourier transform infrared spectroscopy analysis indicate that Pt Pd Cu MEAAs follow the direct pathway via formate as the reactive intermediate to be directly oxidized to CO_(2).For practical direct methanol fuel cells(DMFCs),the Pt Pd Cu MEAAs-integrated ultra-thin catalyst layer(4–5μm thickness)as anode exhibits higher peak power density of 35 m W/cm^(2) than commercial Pt/C of 20 m W/cm^(2)(~40μm thickness)under the similar noble metal loading and an impressive stability retention at a 50-m A/cm^(2) constant current for 10 h.This work clearly proves that optimizing the intermediate adsorption capacity via d-d orbital coupling is an effective strategy to design highly efficient catalysts for DMFCs.展开更多
Lead(Pb)plays a significant role in the nuclear industry and is extensively used in radiation shielding,radiation protection,neutron moderation,radiation measurements,and various other critical functions.Consequently,...Lead(Pb)plays a significant role in the nuclear industry and is extensively used in radiation shielding,radiation protection,neutron moderation,radiation measurements,and various other critical functions.Consequently,the measurement and evaluation of Pb nuclear data are highly regarded in nuclear scientific research,emphasizing its crucial role in the field.Using the time-of-flight(ToF)method,the neutron leakage spectra from three^(nat)Pb samples were measured at 60°and 120°based on the neutronics integral experimental facility at the China Institute of Atomic Energy(CIAE).The^(nat)Pb sample sizes were30 cm×30 cm×5 cm,30 cm×30 cm×10 cm,and 30 cm×30 cm×15 cm.Neutron sources were generated by the Cockcroft-Walton accelerator,producing approximately 14.5 MeV and 3.5 MeV neutrons through the T(d,n)^(4)He and D(d,n)^(3)He reactions,respectively.Leakage neutron spectra were also calculated by employing the Monte Carlo code of MCNP-4C,and the nuclear data of Pb isotopes from four libraries:CENDL-3.2,JEFF-3.3,JENDL-5,and ENDF/B-Ⅷ.0 were used individually.By comparing the simulation and experimental results,improvements and deficiencies in the evaluated nuclear data of the Pb isotopes were analyzed.Most of the calculated results were consistent with the experimental results;however,a few areas did not fit well.In the(n,el)energy range,the simulated results from CENDL-3.2 were significantly overestimated;in the(n,inl)D and the(n,inl)C energy regions,the results from CENDL-3.2 and ENDF/B-Ⅷ.0 were significantly overestimated at 120°,and the results from JENDL-5 and JEFF-3.3 are underestimated at 60°in the(n,inl)D energy region.The calculated spectra were analyzed by comparing them with the experimental spectra in terms of the neutron spectrum shape and C/E values.The results indicate that the theoretical simulations,using different data libraries,overestimated or underestimated the measured values in certain energy ranges.Secondary neutron energies and angular distributions in the data files have been presented to explain these discrepancies.展开更多
目的探讨急性脑梗塞(ACI)患者血清N末端B型利钠肽原(NT-proBNP)/B型利钠肽(BNP)、肌酸激酶同工酶(CK-MB)、D-二聚体(D-D)水平变化及对并发脑心综合征(CCS)的预测价值。方法纳入2020年8月至2023年8月间合肥市第八人民医院收治的ACI患者92...目的探讨急性脑梗塞(ACI)患者血清N末端B型利钠肽原(NT-proBNP)/B型利钠肽(BNP)、肌酸激酶同工酶(CK-MB)、D-二聚体(D-D)水平变化及对并发脑心综合征(CCS)的预测价值。方法纳入2020年8月至2023年8月间合肥市第八人民医院收治的ACI患者92例,根据是否并发CCS分为ACI组58例和CCS组34例,另选取同时期本院招募的健康志愿者50名为对照组。采集各组患者血液,检测NT-proBNP、BNP、CK-MB、D-D水平并计算NT-proBNP/BNP值;统计分析上述指标与ACI患者并发CCS的关系和预测价值。结果各组的NT-proBNP、BNP、NT-proBNP/BNP、CK-MB、D-D水平均有CCS组>ACI组>对照组,差异具有统计学意义(P<0.05);NT-proBNP、BNP、NT-proBNP/BNP、CK-MB、D-D、吸烟、嗜酒、高血压、冠心病、糖尿病、高血脂为发生ACI的危险因素,NT-proBNP、BNP、NT-proBNP/BNP、CK-MB、D-D、吸烟、嗜酒为ACI并发CCS的危险因素(P<0.05);NT-proBNP/BNP、CK-MB、D-D联合诊断ACI并发CCS的曲线下面积(Area under curve,AUC)最大,优于单一检测(P<0.05);NT-proBNP、BNP、NT-proBNP/BNP、CK-MB均与D-D水平正相关(P<0.05)。结论血清NT-proBNP/BNP、CK-MB、D-D水平的升高与ACI患者并发CCS相关,对ACI患者并发CSS均具有预测价值。展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.52073214 and 22075211)Guangxi Natural Science Fund for Distinguished Young Scholars(No.2024GXNSFFA010008)+5 种基金Natural Science Foundation of Shandong Province(Nos.ZR2023MB049 and ZR2021QB129)China Postdoctoral Science Foundation(No.2020M670483)Science Foundation of Weifang University(No.2023BS11)supported by the open research fund of the Laboratory of Xinjiang Native Medicinal and Edible Plant Resources Chemistry at Kashi Universitysupported by the Tianhe Qingsuo Open Research Fund of TSYS in 2022 and NSCC-TJNankai University Large-scale Instrument Experimental Technology R&D Project(No.21NKSYJS09)。
文摘Unraveling the essence of electronic structure effected by d-d orbital coupling of transition metal and methanol oxidation reaction(MOR)performance can fundamentally guide high efficient catalyst design.Herein,density functional theory(DFT)calculations were performed at first to study the d–d orbital interaction of metallic Pt Pd Cu,revealing that the incorporation of Pd and Cu atoms into Pt system can enhance d-d electron interaction via capturing antibonding orbital electrons of Pt to fill the surrounding Pd and Cu atoms.Under the theoretical guidance,Pt Pd Cu medium entropy alloy aerogels(Pt Pd Cu MEAAs)catalysts have been designed and systematically screened for MOR under acid,alkaline and neutral electrolyte.Furthermore,DFT calculation and in-situ fourier transform infrared spectroscopy analysis indicate that Pt Pd Cu MEAAs follow the direct pathway via formate as the reactive intermediate to be directly oxidized to CO_(2).For practical direct methanol fuel cells(DMFCs),the Pt Pd Cu MEAAs-integrated ultra-thin catalyst layer(4–5μm thickness)as anode exhibits higher peak power density of 35 m W/cm^(2) than commercial Pt/C of 20 m W/cm^(2)(~40μm thickness)under the similar noble metal loading and an impressive stability retention at a 50-m A/cm^(2) constant current for 10 h.This work clearly proves that optimizing the intermediate adsorption capacity via d-d orbital coupling is an effective strategy to design highly efficient catalysts for DMFCs.
基金supported by the National Natural Science Foundation of China(Nos.11775311 and U2067205)the Stable Support Basic Research Program Grant(BJ010261223282)the Research and Development Project of China National Nuclear Corporation。
文摘Lead(Pb)plays a significant role in the nuclear industry and is extensively used in radiation shielding,radiation protection,neutron moderation,radiation measurements,and various other critical functions.Consequently,the measurement and evaluation of Pb nuclear data are highly regarded in nuclear scientific research,emphasizing its crucial role in the field.Using the time-of-flight(ToF)method,the neutron leakage spectra from three^(nat)Pb samples were measured at 60°and 120°based on the neutronics integral experimental facility at the China Institute of Atomic Energy(CIAE).The^(nat)Pb sample sizes were30 cm×30 cm×5 cm,30 cm×30 cm×10 cm,and 30 cm×30 cm×15 cm.Neutron sources were generated by the Cockcroft-Walton accelerator,producing approximately 14.5 MeV and 3.5 MeV neutrons through the T(d,n)^(4)He and D(d,n)^(3)He reactions,respectively.Leakage neutron spectra were also calculated by employing the Monte Carlo code of MCNP-4C,and the nuclear data of Pb isotopes from four libraries:CENDL-3.2,JEFF-3.3,JENDL-5,and ENDF/B-Ⅷ.0 were used individually.By comparing the simulation and experimental results,improvements and deficiencies in the evaluated nuclear data of the Pb isotopes were analyzed.Most of the calculated results were consistent with the experimental results;however,a few areas did not fit well.In the(n,el)energy range,the simulated results from CENDL-3.2 were significantly overestimated;in the(n,inl)D and the(n,inl)C energy regions,the results from CENDL-3.2 and ENDF/B-Ⅷ.0 were significantly overestimated at 120°,and the results from JENDL-5 and JEFF-3.3 are underestimated at 60°in the(n,inl)D energy region.The calculated spectra were analyzed by comparing them with the experimental spectra in terms of the neutron spectrum shape and C/E values.The results indicate that the theoretical simulations,using different data libraries,overestimated or underestimated the measured values in certain energy ranges.Secondary neutron energies and angular distributions in the data files have been presented to explain these discrepancies.
文摘目的探讨急性脑梗塞(ACI)患者血清N末端B型利钠肽原(NT-proBNP)/B型利钠肽(BNP)、肌酸激酶同工酶(CK-MB)、D-二聚体(D-D)水平变化及对并发脑心综合征(CCS)的预测价值。方法纳入2020年8月至2023年8月间合肥市第八人民医院收治的ACI患者92例,根据是否并发CCS分为ACI组58例和CCS组34例,另选取同时期本院招募的健康志愿者50名为对照组。采集各组患者血液,检测NT-proBNP、BNP、CK-MB、D-D水平并计算NT-proBNP/BNP值;统计分析上述指标与ACI患者并发CCS的关系和预测价值。结果各组的NT-proBNP、BNP、NT-proBNP/BNP、CK-MB、D-D水平均有CCS组>ACI组>对照组,差异具有统计学意义(P<0.05);NT-proBNP、BNP、NT-proBNP/BNP、CK-MB、D-D、吸烟、嗜酒、高血压、冠心病、糖尿病、高血脂为发生ACI的危险因素,NT-proBNP、BNP、NT-proBNP/BNP、CK-MB、D-D、吸烟、嗜酒为ACI并发CCS的危险因素(P<0.05);NT-proBNP/BNP、CK-MB、D-D联合诊断ACI并发CCS的曲线下面积(Area under curve,AUC)最大,优于单一检测(P<0.05);NT-proBNP、BNP、NT-proBNP/BNP、CK-MB均与D-D水平正相关(P<0.05)。结论血清NT-proBNP/BNP、CK-MB、D-D水平的升高与ACI患者并发CCS相关,对ACI患者并发CSS均具有预测价值。
