The development of highly active and stable bifunctional electrocatalysts in acidic media is crucial to hydrogen production by proton exchange membrane.In this study,we designed a RuO_(2)-IrO_(2)heterostructure cataly...The development of highly active and stable bifunctional electrocatalysts in acidic media is crucial to hydrogen production by proton exchange membrane.In this study,we designed a RuO_(2)-IrO_(2)heterostructure catalyst coupled by carbon quantum dots(CQDs).The catalyst showed excellent electrocatalytic performance for water splitting under acidic conditions.The overpotentials of oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)were as low as 180 and 15 mV at 10 mA/cm^(2)in 0.5 M H_(2)SO_(4),respectively.The acid electrolytic cell developed with RuO_(2)-IrO_(2)@CQDs as anode and cathode operated stably at 10 m A/cm^(2)for 120 h.In situ measurements and theoretical calculation reveal that the unique lattice oxygen mechanism path of RuO_(2)-IrO_(2)@CQDs can bypass the OOH^(*)intermediate and breaks the linear relationship of adsorbent evolution mechanism path,resulting in higher OER catalytic activity.展开更多
Salinization in estuarine wetlands significantly alters the balance between their nitrogen(N)removal and retention abilities but these processes have not yet been characterized effectively.In the present study,the pot...Salinization in estuarine wetlands significantly alters the balance between their nitrogen(N)removal and retention abilities but these processes have not yet been characterized effectively.In the present study,the potential rates of sediment denitrification,anaerobic ammonium oxidation(anammox),and dissimilatory nitrate reduction to ammonium(DNRA)were mapped using N isotope tracing methods along salinity gradients across the Yellow River Delta wetland(YRDW)in China.The contribution of anammox to total dissimilatory N transformations in YRDW was merely 6.8%,whereas denitrification and DNRA contributed 52.3%and 40.9%,respectively.The potential rate of denitrification(5.82μmol/kg/h)decreased significantly along salinity gradients and markedly exceeded DNRA potential rate(2.7μmol/kg/h)in fresh wetlands,but was lower than that of DNRA in oligohaline wetlands(3.06 and 3.18μmol/kg/h,respectively).Moreover,a significantly positive relationship between salinity and DNRA/denitrification was obeserved,indicating that increased salinity may favor DNRA over denitrification.Furthermore,total sulfur(TS)content and ratio of total organic carbon to total nitrogen(C/N)increased with the salinity gradient and showed evident positive relationships with the DNRA/denitrification ratio.In this study,we proved that increased salinization resulted in the dominance of DNRA over denitrification,possible through the addition of S and alteration of the C/N in estuarine wetlands,leading to increased N retention in estuarine wetlands during salinization,which would enhance the eutrophication potential within wetlands and in downstream ecosystems.展开更多
Iron-chromium redox flow batteries (ICRFBs) possess advantages of high safety,long cycle time,and lowcost.Increasing Cr^(3+)/Cr^(2+)reaction activity is suggested as one of the most promising strategies to improve the...Iron-chromium redox flow batteries (ICRFBs) possess advantages of high safety,long cycle time,and lowcost.Increasing Cr^(3+)/Cr^(2+)reaction activity is suggested as one of the most promising strategies to improve the performance and prolong the lifetime of ICRFBs.To improve the slow reaction kinetics of the negative electrode,a type of defected carbon cloth with Bismuth (Bi) catalyst introduction is prepared by defect engineering method and electrochemical deposition,which provided defect sites and active sites to catalyze the redox couple’s reaction of ICRFBs.Furthermore,this modified carbon cloth adsorbs Cr(Ⅲ)hydrate more easily,which has a more stable structure and can significantly improve the performance of ICRFBs.Both experimental analysis and theoretical calculation indicated that the modified electrode has excellent electrocatalytic ability,which can enhance the reaction rate of Cr^(3+)/Cr^(2+),improve capacity retention and stabilize cycling performance.The capacity degradation rate of an ICRFB single cell with the modified electrodes is just 0.23%per cycle at a current density of 140 m A/cm^(2).Additionally,the energy efficiency (EE) remains around 83%,which is 8.45%higher than that of the pristine electrode assembled battery under 60 cycles.This work supplies a simple method to obtain a high-performance electrode material for ICRFBs and makes it a practical solution to promote ICFRBs large-scale commercialization process.展开更多
A silylated melamine sponge(SMS)was prepared by two simple steps,namely,immersion and dehydration of a melamine sponge coated with methyltrichlorosilane.The silylated structure of SMS was characterized by FT-IR(Fourie...A silylated melamine sponge(SMS)was prepared by two simple steps,namely,immersion and dehydration of a melamine sponge coated with methyltrichlorosilane.The silylated structure of SMS was characterized by FT-IR(Fourier-transform infrared)spectroscopy,SEM(Scanning electron microscopy)and in terms of water contact angles.Its oil-water absorption and separation capacities were measured by FT-IR and UV-visible spectrophoto-metry.The experimental results have shown that oligomeric silanol covalently bonds by Si-N onto the surface of melamine sponge skeletons.SMS has shown superhydrophobicity with a water contact angle exceeding 150°±1°,a better separation efficiency with regard to diesel oil(by 99.31%(wt/wt%)in oil-water mixture and even up to 99.99%(wt/wt%)for diesel oil in its saturated aqueous solution.Moreover,SMS inherited the intrinsicflame retardancy of the melamine sponge.In general,SMS has shown superhydrophobicity,high porosity,excellent selectivity,remarkable recyclability,and better absorption capacity for various oils and organic solvents,and a high separation efficiency for oil in saturated aqueous solutions.展开更多
The interfaces of perovskite solar cells(PSCs)are well known to be rich in deep-level carrier traps,which serve as non-radiative recombination centers and limit the open-circuit voltage(Voc)and power conversion effici...The interfaces of perovskite solar cells(PSCs)are well known to be rich in deep-level carrier traps,which serve as non-radiative recombination centers and limit the open-circuit voltage(Voc)and power conversion efficiency(PCE)of PSCs.Defect chemistry and surface passivators have been researched extensively and mainly focused on the neutralization of uncoordinated lead or anion defects.Herein,a novel brominated passivator 2-bromophenethylammonium iodide(2-Br-PEAI)is introduced for a multi-functional passivation effect at the perovskite interface.The brominated species readily form 2D perovskite on top of the 3D perovskite and multi-interact with the 3D perovskite surface.Apart from the halide vacancy filling and anion bonding ability,the Br atoms on the benzene ring can interact with the FA cations via strong hydrogen bonding N-H…Br and interact with the[PbI_(6)]^(4−)inorganic framework.The interface defects in the PSCs are well passivated,minimizing non-radiative recombination and enhancing device performance.As a result,a champion PCE of 24.22%was achieved with high V_(oc)and fill factor.In addition,modified devices also showed enhanced operational stability(retention of>95%initial PCE after 400 h)and humidity resistance(>90%initial PCE maintained after 1500 h under~50%RH).展开更多
To generate high-frequency radio frequency(RF) vector signals, a vector signal generation method by optical frequency sextupling using a dual-parallel modulator is proposed. The method modulates vector signal on +3 rd...To generate high-frequency radio frequency(RF) vector signals, a vector signal generation method by optical frequency sextupling using a dual-parallel modulator is proposed. The method modulates vector signal on +3 rd order optical sideband and local oscillator(LO) signal on-3 rd order sideband using the intermodulation process in the DPMZM. After suppressing of the optical carrier and other sidebands through proper adjustment for modulator biases and modulation index, a frequency sextupled millimeter-wave vector signal can be generated after photodetection. The frequency sextupling will lower the bandwidth of the modulator, the local oscillator and the driving circuits. In addition, the phase of generated signal is not distorted after detection, and the power fading after fiber transmission can be avoided. In the simulation, a 500-MSym/s QPSK signal at 60 GHz is generated by 10-GHz drive signal. After travelling over fiber with length of 20/30/40-km, receiver power penalty keeps below 2.5 dB.展开更多
Carbon monoxide(CO)stands as one of the most valuable and economically viable products in the electrochemical reduction of CO_(2).In this study,we introduced high-surface-area porous carbon and anion-exchange ionomer ...Carbon monoxide(CO)stands as one of the most valuable and economically viable products in the electrochemical reduction of CO_(2).In this study,we introduced high-surface-area porous carbon and anion-exchange ionomer to silver nanoparticles,rapidly constructing a tri-phase interface that enhances CO_(2)transport and proton conduction.The ionomer-encapsulated tri-phase interface further improves reaction selectivity by increasing HCO_(3)^(-)concentration.Flow cell tests revealed that the 80%Ag/C catalyst doubles the partial current density of CO as compared to commercial Ag nanoparticles.To integrate the synthesized 80%Ag/C into industrial-scale membrane electrode assembly(MEA)electrolyzers(10 cm×10 cm),we developed a comprehensive evaluation system incorporating CO selectivity,cell voltage,and actual gas conversion ratio(λ_(act))with only one piece of MEA.This approach allowed systematic evaluation of current density and gas flow rate effects,followed by operational parameter optimization to 300 mA·cm^(-2)and 1000 standard cubic centimeters per minute(sccm).Under optimal conditions,the 80%Ag/C catalyst demonstrated stable operation for over 60 h with a cell voltage of 3 V.The observed CO Faradaic efficiency decay rate suggests a projected operational lifetime exceeding 500 h.This work not only presents an efficient modification strategy to enhance the CO_(2)reduction performance of silver-based catalysts,but also establishes a design-of-experiment(DOE)methodology for industrial-scale testing conditions optimization,thereby facilitating the advancement of CO_(2)reduction reaction(CO_(2)RR)toward practical industrial applications.展开更多
目的:探讨红细胞分布宽度/白蛋白比值(red blood cell distribution width-to-albumin ratio,RAR)与白蛋白–胆红素(albumin–bilirubin,ALBI)评分联合(ALBI-RAR)在肝细胞癌(hepatocellular carcinoma,HCC)根治性切除术后复发风险预测...目的:探讨红细胞分布宽度/白蛋白比值(red blood cell distribution width-to-albumin ratio,RAR)与白蛋白–胆红素(albumin–bilirubin,ALBI)评分联合(ALBI-RAR)在肝细胞癌(hepatocellular carcinoma,HCC)根治性切除术后复发风险预测中的价值,并比较其与单一指标的预测性能。方法:回顾性分析2013年1月至2023年12月在兰州大学第二医院接受肝切除术的257例HCC患者的临床资料,收集术前一般信息、实验室指标、肿瘤学特征及随访数据。通过受试者工作特征曲线(receiver operating characteristic curve,ROC)分析确定RAR的最佳截断值(3.245),并据此建立RAR分级及ALBI-RAR联合评分分组。以无复发生存期(recurrence-free survival,RFS)为终点,采用Kaplan–Meier法绘制生存曲线并行Log-rank检验,利用Cox比例风险回归分析复发的独立危险因素,并通过时间依赖性ROC曲线(最近邻估计法)评估预测性能。结果:单因素分析显示,肿瘤最大径、TNM分期、白蛋白水平、ALBI评分、RAR分级及ALBI-RAR联合评分均与术后复发显著相关(P<0.05);多因素分析证实,ALBI-RAR联合评分为术后复发的独立危险因素:与1级相比,4级复发风险显著升高(HR=14.6,95%CI:1.8~118.0,P=0.012)。Kaplan–Meier分析显示联合评分在不同风险层级间的RFS区分最为明显(1~4级中位RFS为96、48、24和5个月,P<0.0001),优于单独的ALBI或RAR。36个月时,ALBI、RAR及ALBI-RAR的曲线下面积(area under the curve,AUC)分别为0.715、0.709和0.751,联合评分预测性能最高。结论:ALBI-RAR联合评分能够更准确地区分HCC根治性切除术后不同复发风险患者,预测性能优于单项指标,具有简便、客观且可重复的优势,可为术前风险评估及个体化随访策略制定提供有力依据。展开更多
Hypobaric and hypoxic conditions in high-altitude areas have adverse effects on the respiratory system,circulatory system,and nervous system,and these effects have unique impacts on human health and survival.Owing to ...Hypobaric and hypoxic conditions in high-altitude areas have adverse effects on the respiratory system,circulatory system,and nervous system,and these effects have unique impacts on human health and survival.Owing to the geography and climate of these regions,long-term residents face a variety of health challenges.High-altitude hypoxia can cause symptoms of altitude sickness,such as insomnia,headache,nausea and dyspnea,and in severe cases,high altitude pulmonary edema or high altitude cerebral edema.Human populations that have inhabited high-altitude envi-ronments for thousands of years,including Andeans.展开更多
基金supported by the Natural Science Foundation of Shandong Province ZR2024MB087the National Natural Science Foundation of China(No.52122308,51973200,52202050,and 21905253)+3 种基金the Natural Science Foundation of Henan(202300410372)the Joint Fund of Science and Technology R&D Plan of Henan Province(232301420042)the China Postdoctoral Science Foundation(2022TQ0286)the Center for Modern Analysis and Gene Sequencing of Zhengzhou University for supporting this project。
文摘The development of highly active and stable bifunctional electrocatalysts in acidic media is crucial to hydrogen production by proton exchange membrane.In this study,we designed a RuO_(2)-IrO_(2)heterostructure catalyst coupled by carbon quantum dots(CQDs).The catalyst showed excellent electrocatalytic performance for water splitting under acidic conditions.The overpotentials of oxygen evolution reaction(OER)and hydrogen evolution reaction(HER)were as low as 180 and 15 mV at 10 mA/cm^(2)in 0.5 M H_(2)SO_(4),respectively.The acid electrolytic cell developed with RuO_(2)-IrO_(2)@CQDs as anode and cathode operated stably at 10 m A/cm^(2)for 120 h.In situ measurements and theoretical calculation reveal that the unique lattice oxygen mechanism path of RuO_(2)-IrO_(2)@CQDs can bypass the OOH^(*)intermediate and breaks the linear relationship of adsorbent evolution mechanism path,resulting in higher OER catalytic activity.
基金supported by the National Key Research and Development Program of China(No.2017YFC0404401)the Central Public-interest Scientific Institution Basal Research Fund(No.HKY-JBYW-2018-07)。
文摘Salinization in estuarine wetlands significantly alters the balance between their nitrogen(N)removal and retention abilities but these processes have not yet been characterized effectively.In the present study,the potential rates of sediment denitrification,anaerobic ammonium oxidation(anammox),and dissimilatory nitrate reduction to ammonium(DNRA)were mapped using N isotope tracing methods along salinity gradients across the Yellow River Delta wetland(YRDW)in China.The contribution of anammox to total dissimilatory N transformations in YRDW was merely 6.8%,whereas denitrification and DNRA contributed 52.3%and 40.9%,respectively.The potential rate of denitrification(5.82μmol/kg/h)decreased significantly along salinity gradients and markedly exceeded DNRA potential rate(2.7μmol/kg/h)in fresh wetlands,but was lower than that of DNRA in oligohaline wetlands(3.06 and 3.18μmol/kg/h,respectively).Moreover,a significantly positive relationship between salinity and DNRA/denitrification was obeserved,indicating that increased salinity may favor DNRA over denitrification.Furthermore,total sulfur(TS)content and ratio of total organic carbon to total nitrogen(C/N)increased with the salinity gradient and showed evident positive relationships with the DNRA/denitrification ratio.In this study,we proved that increased salinization resulted in the dominance of DNRA over denitrification,possible through the addition of S and alteration of the C/N in estuarine wetlands,leading to increased N retention in estuarine wetlands during salinization,which would enhance the eutrophication potential within wetlands and in downstream ecosystems.
基金supported by the National Natural Science Foundation of China(No.52211530034)General project of Beijing Natural Science Fund(No.3222018)。
文摘Iron-chromium redox flow batteries (ICRFBs) possess advantages of high safety,long cycle time,and lowcost.Increasing Cr^(3+)/Cr^(2+)reaction activity is suggested as one of the most promising strategies to improve the performance and prolong the lifetime of ICRFBs.To improve the slow reaction kinetics of the negative electrode,a type of defected carbon cloth with Bismuth (Bi) catalyst introduction is prepared by defect engineering method and electrochemical deposition,which provided defect sites and active sites to catalyze the redox couple’s reaction of ICRFBs.Furthermore,this modified carbon cloth adsorbs Cr(Ⅲ)hydrate more easily,which has a more stable structure and can significantly improve the performance of ICRFBs.Both experimental analysis and theoretical calculation indicated that the modified electrode has excellent electrocatalytic ability,which can enhance the reaction rate of Cr^(3+)/Cr^(2+),improve capacity retention and stabilize cycling performance.The capacity degradation rate of an ICRFB single cell with the modified electrodes is just 0.23%per cycle at a current density of 140 m A/cm^(2).Additionally,the energy efficiency (EE) remains around 83%,which is 8.45%higher than that of the pristine electrode assembled battery under 60 cycles.This work supplies a simple method to obtain a high-performance electrode material for ICRFBs and makes it a practical solution to promote ICFRBs large-scale commercialization process.
基金funded by Qingyang Science and Technology Support Project(KT2019-03)。
文摘A silylated melamine sponge(SMS)was prepared by two simple steps,namely,immersion and dehydration of a melamine sponge coated with methyltrichlorosilane.The silylated structure of SMS was characterized by FT-IR(Fourier-transform infrared)spectroscopy,SEM(Scanning electron microscopy)and in terms of water contact angles.Its oil-water absorption and separation capacities were measured by FT-IR and UV-visible spectrophoto-metry.The experimental results have shown that oligomeric silanol covalently bonds by Si-N onto the surface of melamine sponge skeletons.SMS has shown superhydrophobicity with a water contact angle exceeding 150°±1°,a better separation efficiency with regard to diesel oil(by 99.31%(wt/wt%)in oil-water mixture and even up to 99.99%(wt/wt%)for diesel oil in its saturated aqueous solution.Moreover,SMS inherited the intrinsicflame retardancy of the melamine sponge.In general,SMS has shown superhydrophobicity,high porosity,excellent selectivity,remarkable recyclability,and better absorption capacity for various oils and organic solvents,and a high separation efficiency for oil in saturated aqueous solutions.
基金supported by the National Natural Science Foundation of China(21872080)State Key Laboratory of Power System and Generation Equipment(No.SKLD21Z03,SKLD20M03)China Postdoctoral Science Foundation(No.043240004).
文摘The interfaces of perovskite solar cells(PSCs)are well known to be rich in deep-level carrier traps,which serve as non-radiative recombination centers and limit the open-circuit voltage(Voc)and power conversion efficiency(PCE)of PSCs.Defect chemistry and surface passivators have been researched extensively and mainly focused on the neutralization of uncoordinated lead or anion defects.Herein,a novel brominated passivator 2-bromophenethylammonium iodide(2-Br-PEAI)is introduced for a multi-functional passivation effect at the perovskite interface.The brominated species readily form 2D perovskite on top of the 3D perovskite and multi-interact with the 3D perovskite surface.Apart from the halide vacancy filling and anion bonding ability,the Br atoms on the benzene ring can interact with the FA cations via strong hydrogen bonding N-H…Br and interact with the[PbI_(6)]^(4−)inorganic framework.The interface defects in the PSCs are well passivated,minimizing non-radiative recombination and enhancing device performance.As a result,a champion PCE of 24.22%was achieved with high V_(oc)and fill factor.In addition,modified devices also showed enhanced operational stability(retention of>95%initial PCE after 400 h)and humidity resistance(>90%initial PCE maintained after 1500 h under~50%RH).
基金Sponsored by the Programme of Introducing Talents of Discipline to Universities(Grant No.B08038)
文摘To generate high-frequency radio frequency(RF) vector signals, a vector signal generation method by optical frequency sextupling using a dual-parallel modulator is proposed. The method modulates vector signal on +3 rd order optical sideband and local oscillator(LO) signal on-3 rd order sideband using the intermodulation process in the DPMZM. After suppressing of the optical carrier and other sidebands through proper adjustment for modulator biases and modulation index, a frequency sextupled millimeter-wave vector signal can be generated after photodetection. The frequency sextupling will lower the bandwidth of the modulator, the local oscillator and the driving circuits. In addition, the phase of generated signal is not distorted after detection, and the power fading after fiber transmission can be avoided. In the simulation, a 500-MSym/s QPSK signal at 60 GHz is generated by 10-GHz drive signal. After travelling over fiber with length of 20/30/40-km, receiver power penalty keeps below 2.5 dB.
基金supported by the National Natural Science Foundation of China(No.22175127).
文摘Carbon monoxide(CO)stands as one of the most valuable and economically viable products in the electrochemical reduction of CO_(2).In this study,we introduced high-surface-area porous carbon and anion-exchange ionomer to silver nanoparticles,rapidly constructing a tri-phase interface that enhances CO_(2)transport and proton conduction.The ionomer-encapsulated tri-phase interface further improves reaction selectivity by increasing HCO_(3)^(-)concentration.Flow cell tests revealed that the 80%Ag/C catalyst doubles the partial current density of CO as compared to commercial Ag nanoparticles.To integrate the synthesized 80%Ag/C into industrial-scale membrane electrode assembly(MEA)electrolyzers(10 cm×10 cm),we developed a comprehensive evaluation system incorporating CO selectivity,cell voltage,and actual gas conversion ratio(λ_(act))with only one piece of MEA.This approach allowed systematic evaluation of current density and gas flow rate effects,followed by operational parameter optimization to 300 mA·cm^(-2)and 1000 standard cubic centimeters per minute(sccm).Under optimal conditions,the 80%Ag/C catalyst demonstrated stable operation for over 60 h with a cell voltage of 3 V.The observed CO Faradaic efficiency decay rate suggests a projected operational lifetime exceeding 500 h.This work not only presents an efficient modification strategy to enhance the CO_(2)reduction performance of silver-based catalysts,but also establishes a design-of-experiment(DOE)methodology for industrial-scale testing conditions optimization,thereby facilitating the advancement of CO_(2)reduction reaction(CO_(2)RR)toward practical industrial applications.
文摘目的:探讨红细胞分布宽度/白蛋白比值(red blood cell distribution width-to-albumin ratio,RAR)与白蛋白–胆红素(albumin–bilirubin,ALBI)评分联合(ALBI-RAR)在肝细胞癌(hepatocellular carcinoma,HCC)根治性切除术后复发风险预测中的价值,并比较其与单一指标的预测性能。方法:回顾性分析2013年1月至2023年12月在兰州大学第二医院接受肝切除术的257例HCC患者的临床资料,收集术前一般信息、实验室指标、肿瘤学特征及随访数据。通过受试者工作特征曲线(receiver operating characteristic curve,ROC)分析确定RAR的最佳截断值(3.245),并据此建立RAR分级及ALBI-RAR联合评分分组。以无复发生存期(recurrence-free survival,RFS)为终点,采用Kaplan–Meier法绘制生存曲线并行Log-rank检验,利用Cox比例风险回归分析复发的独立危险因素,并通过时间依赖性ROC曲线(最近邻估计法)评估预测性能。结果:单因素分析显示,肿瘤最大径、TNM分期、白蛋白水平、ALBI评分、RAR分级及ALBI-RAR联合评分均与术后复发显著相关(P<0.05);多因素分析证实,ALBI-RAR联合评分为术后复发的独立危险因素:与1级相比,4级复发风险显著升高(HR=14.6,95%CI:1.8~118.0,P=0.012)。Kaplan–Meier分析显示联合评分在不同风险层级间的RFS区分最为明显(1~4级中位RFS为96、48、24和5个月,P<0.0001),优于单独的ALBI或RAR。36个月时,ALBI、RAR及ALBI-RAR的曲线下面积(area under the curve,AUC)分别为0.715、0.709和0.751,联合评分预测性能最高。结论:ALBI-RAR联合评分能够更准确地区分HCC根治性切除术后不同复发风险患者,预测性能优于单项指标,具有简便、客观且可重复的优势,可为术前风险评估及个体化随访策略制定提供有力依据。
基金supported by the National Natural Science Foundation of China(No.82200762)the Postdoctoral Fellowship Program of China Postdoctoral Science Foundation(No.GZC20242289)research grants from the Natural Foundation of Shigatse.
文摘Hypobaric and hypoxic conditions in high-altitude areas have adverse effects on the respiratory system,circulatory system,and nervous system,and these effects have unique impacts on human health and survival.Owing to the geography and climate of these regions,long-term residents face a variety of health challenges.High-altitude hypoxia can cause symptoms of altitude sickness,such as insomnia,headache,nausea and dyspnea,and in severe cases,high altitude pulmonary edema or high altitude cerebral edema.Human populations that have inhabited high-altitude envi-ronments for thousands of years,including Andeans.
