Zeolite X was synthesized by a two-step hydrothermal method using natural stellerite zeolite as the silicon seed,and its adsorption performance for Cd^(2+)and Ni^(2+)ions was experimentally and comprehensively investi...Zeolite X was synthesized by a two-step hydrothermal method using natural stellerite zeolite as the silicon seed,and its adsorption performance for Cd^(2+)and Ni^(2+)ions was experimentally and comprehensively investigated.The effects of p H,zeolite X dosage,contact time,and temperature on adsorption performance for Cd^(2+)and Ni^(2+)ions over were studied.The adsorption process was endothermic and spontaneous,and followed the pseudo-second-order kinetic and the Langmuir isotherm models.The maximum adsorption capacitiesfor Cd^(2+)and Ni^(2+)ions at 298 K were 173.553 and 75.897 mg.g-1,respectively.Ion exchange and precipitation were the principal mechanisms for the removal of Cd^(2+)ions from aqueous solutions by zeolite X,followed by electrostatic adsorption.Ion exchange was the principal mechanisms for the removal of Ni^(2+)ions from aqueous solutions by zeolite X,followed by electrostatic adsorption and precipitation.The zeolite X converted from stellerite zeolite has a low n(Si/Al),abundant hydroxyl groups,and high crystallinity and purity,imparting a good adsorption performance for Cd^(2+)and Ni^(2+)ions.This study suggests that zeolite X converted from stellerite zeolite could be a useful environmentally-friendly and effective tool for the removal of Cd^(2+)and Ni^(2+)ions from aqueous solutions.展开更多
Although LanTAaou is one of the most heavily polluted cities in China, the composition of its air pollutants have not yet been studied in detail. The data of four months on the concentrations and compositions of ions ...Although LanTAaou is one of the most heavily polluted cities in China, the composition of its air pollutants have not yet been studied in detail. The data of four months on the concentrations and compositions of ions from daily air-filter samples in the winter and spring during 2007-2008 were analyzed to investigate temporal trends and their possible causes. The results indicate that mean concentrations of almost all the aerosol components are greater in winter than in spring due to stronger emissions in winter and weaker localized dispersion. Spring dust storms are the major cause of the highest peak PM10 concentrations recorded during the study period; however, these elevated levels were transient. Ion concentrations related to coal combustion show the greatest reduction from winter to spring, while the concentrations of strong crustal components show a less-pronounced reduction. Strong cycles in the levels of particulate matter （PM） and all ions are also observed during the winter months due to meteorological conditions. Depending on the season, nine different ions accounted for 20%-50% of the PM concentration. The particle size of polluting ions was constant at times of increasing PM concentrations （particularly during winter）, whereas the particle size of crustal ions in- creased dramatically during spring dust storms. Local meteorological conditions （especially wind speed） have a strong influence on the levels of pollutants. Four dust storms were noted, including one during winter. In summary, the regional transport of desert dust from the Gobi can significantly affect air quality and the chemical composition of aerosols in Lanzhou. The dust storms can strongly increase concentration of crustal ions, which are characteristics of deserts in northwestern China. This observation is in agreement with back-trajectories, which show reduced levels of pollutant ions during dust storms. Data on nitrate：sulfate ratios indicate that stationary point sources are the main source of ions rather than mobile sources.展开更多
Wadsley-Roth (W-R) structured oxides featured with wide channels represent one of the most promising material families showing compelling rate performance for lithium-ion batteries.Herein,we report an indepth study on...Wadsley-Roth (W-R) structured oxides featured with wide channels represent one of the most promising material families showing compelling rate performance for lithium-ion batteries.Herein,we report an indepth study on the fast and extensive intercalation chemistry of phosphorus stabilized W-R phase PNb_(9)O_(25) and its application in high energy and fast-charging devices.We explore the intercalation geometry of PNb_(9)O_(25) and identify two geometrical types of stable insertion sites with the total amount much higher than conventional intercalation-type electrodes.We reveal the ion transportation kinetics that the Li ions initially diffuse along the open type Ⅲ channels and then penetrate to edge sites with low kinetic barriers.During the lithiation,no remarkable phase transition is detected with nearly intact host phosphorous niobium oxide backbone.Therefore,the oxide framework of PNb_(9)O_(25) keeps almost unchanged with all the fast diffusion channels and insertion cavities well-maintained upon cycling,which accomplishes the unconventional electrochemical performance of W-R structured electrodes.展开更多
If the operating voltage of anode materials is below 1.0 V versus Lit/Li,the side reaction between electrolyte and anode materials will occur extensively.Thus,high-voltage anode materials have aroused interest recentl...If the operating voltage of anode materials is below 1.0 V versus Lit/Li,the side reaction between electrolyte and anode materials will occur extensively.Thus,high-voltage anode materials have aroused interest recently.In this work,we report the preparation of PNb9O25 nanofiber via a facile electrospinning method.The PNb9O25 nanofiber shows the high rate performance and excellent cycling performance when it is used as anode in lithium ions batteries.For instance,the PNb9O25 nanofiber can deliver a capacity of 233,212.1,193.8,and 181.4 mA h g^(-1) at 0.2,1,3,and 6C,respectively.After 1000 cycles,it can reach at 134.3 mA h g^(-1) with capacity retention of 70.9%.Meanwhile,the ex situ X-ray photoelectron spectroscopy technique has been adopted to investigate the evolution in valence state of each element for PNb9O25 nanofiber.In addition,the PNb9O25 nanofiber is chosen as the anode material in lithium ion full cell in this work,demonstrating the potential for practical application.展开更多
The transition energies, wavelengths and oscillator strengths for the ls22s-ls2np （n≤9） transitions of Ni25＋ ion are calculated. In calculation of the energies, we not only take account of the first- order correct...The transition energies, wavelengths and oscillator strengths for the ls22s-ls2np （n≤9） transitions of Ni25＋ ion are calculated. In calculation of the energies, we not only take account of the first- order corrections from relativistic and mass-polarization effects, but also estimate the higher-order relativistic contribution and QED correction by introducing the effective nuclear charge. The results agree with experimental data available in literature satisfactorily. Grotrian diagram showing these transitions is given.展开更多
基金supported by the National Natural Science Foundation of China(51564008,41662005)Natural Science Foundation of Guangxi Province(2019GXNSFBA245083)。
文摘Zeolite X was synthesized by a two-step hydrothermal method using natural stellerite zeolite as the silicon seed,and its adsorption performance for Cd^(2+)and Ni^(2+)ions was experimentally and comprehensively investigated.The effects of p H,zeolite X dosage,contact time,and temperature on adsorption performance for Cd^(2+)and Ni^(2+)ions over were studied.The adsorption process was endothermic and spontaneous,and followed the pseudo-second-order kinetic and the Langmuir isotherm models.The maximum adsorption capacitiesfor Cd^(2+)and Ni^(2+)ions at 298 K were 173.553 and 75.897 mg.g-1,respectively.Ion exchange and precipitation were the principal mechanisms for the removal of Cd^(2+)ions from aqueous solutions by zeolite X,followed by electrostatic adsorption.Ion exchange was the principal mechanisms for the removal of Ni^(2+)ions from aqueous solutions by zeolite X,followed by electrostatic adsorption and precipitation.The zeolite X converted from stellerite zeolite has a low n(Si/Al),abundant hydroxyl groups,and high crystallinity and purity,imparting a good adsorption performance for Cd^(2+)and Ni^(2+)ions.This study suggests that zeolite X converted from stellerite zeolite could be a useful environmentally-friendly and effective tool for the removal of Cd^(2+)and Ni^(2+)ions from aqueous solutions.
文摘目的:探究急性缺血性脑卒中(Acute ischemic stroke,AIS)患者入院时血清25羟维生素D_(3)(25-hydroxyl vitamin D3,25-(OH)D3)、镁离子(Magnesium,Mg^(2+))、低密度脂蛋白胆固醇(Low density lipoprotein cholesterol,LDL-C)水平的变化及预测近期结局的价值。方法:回顾性分析2021年1月至2023年11月本院收治的67例AIS患者及同期60例健康者的临床资料,比较两组血清25(OH)D3、Mg^(2+)、LDL-C水平的差异;应用美国国立卫生院卒中量表将AIS患者按病情严重程度分为轻度组(n=25)、中度组(n=22)和重度组(n=20),比较三组上述指标的差异;同时出院后随访3 m以改良Rankin评分评价AIS近期结局,比较不同预后组上述指标的差异并应用受试者工作特征(Receiver operating characteristic,ROC)曲线和曲线下面积(Area under the curve,AUC)分析其预测价值。结果:AIS组血清25(OH)D3、Mg^(2+)水平低于健康组,LDL-C水平高于对照组(P<0.05);重度组AIS患者血清25(OH)D3、Mg^(2+)水平均低于中度组及轻度组,LDL-C水平高于中度组及轻度组(P<0.05);随访3 m将AIS患者分为预后不良组(n=29)和预后良好组(n=38),预后不良组血清25(OH)D3、Mg^(2+)水平低于预后良好组,LDL-C水平高于预后良好组(P<0.05);ROC分析显示,血清25(OH)D3、Mg^(2+)、LDL-C单独和联合检查的AUC分别为0.784、0.806、0.884、1.000,对AIS患者近期结局的预测均具有一定的价值(P<0.05),对不良预后的预测均具有一定的价值(P<0.05)。结论:AIS患者多表现血清25(OH)D3、Mg^(2+)水平下降和LDL-C水平升高,对于近期结局的预测具有一定的价值。
基金supported by the National Special Project for Commonweal Industry in China (GYHY201106034)the National Support Project for Science and Technology of China (2007BAC29B03+1 种基金 2009BAC53B02)the Project of National Natural Science Foundation of China(41075103)
文摘Although LanTAaou is one of the most heavily polluted cities in China, the composition of its air pollutants have not yet been studied in detail. The data of four months on the concentrations and compositions of ions from daily air-filter samples in the winter and spring during 2007-2008 were analyzed to investigate temporal trends and their possible causes. The results indicate that mean concentrations of almost all the aerosol components are greater in winter than in spring due to stronger emissions in winter and weaker localized dispersion. Spring dust storms are the major cause of the highest peak PM10 concentrations recorded during the study period; however, these elevated levels were transient. Ion concentrations related to coal combustion show the greatest reduction from winter to spring, while the concentrations of strong crustal components show a less-pronounced reduction. Strong cycles in the levels of particulate matter （PM） and all ions are also observed during the winter months due to meteorological conditions. Depending on the season, nine different ions accounted for 20%-50% of the PM concentration. The particle size of polluting ions was constant at times of increasing PM concentrations （particularly during winter）, whereas the particle size of crustal ions in- creased dramatically during spring dust storms. Local meteorological conditions （especially wind speed） have a strong influence on the levels of pollutants. Four dust storms were noted, including one during winter. In summary, the regional transport of desert dust from the Gobi can significantly affect air quality and the chemical composition of aerosols in Lanzhou. The dust storms can strongly increase concentration of crustal ions, which are characteristics of deserts in northwestern China. This observation is in agreement with back-trajectories, which show reduced levels of pollutant ions during dust storms. Data on nitrate：sulfate ratios indicate that stationary point sources are the main source of ions rather than mobile sources.
基金supported by the National Natural Science Foundation of China (51774251)the Hebei Natural Science Foundation for Distinguished Young Scholars (B2017203313)+7 种基金the Hundred Excellent Innovative Talents Support Program in Hebei Province (SLRC2017057)the Scientific Research Foundation for the Returned Overseas Chinese Scholars (CG2014003002)the Canada Foundation for Innovationthe Government of OntarioOntario Research Fund - Research Excellencethe University of Torontosupported by the National Natural Science Foundation of China (51702207 and 11972219)the Program for Professor of Special Appointment (Young Eastern Scholar Program) at Shanghai Institutions of Higher Learning。
文摘Wadsley-Roth (W-R) structured oxides featured with wide channels represent one of the most promising material families showing compelling rate performance for lithium-ion batteries.Herein,we report an indepth study on the fast and extensive intercalation chemistry of phosphorus stabilized W-R phase PNb_(9)O_(25) and its application in high energy and fast-charging devices.We explore the intercalation geometry of PNb_(9)O_(25) and identify two geometrical types of stable insertion sites with the total amount much higher than conventional intercalation-type electrodes.We reveal the ion transportation kinetics that the Li ions initially diffuse along the open type Ⅲ channels and then penetrate to edge sites with low kinetic barriers.During the lithiation,no remarkable phase transition is detected with nearly intact host phosphorous niobium oxide backbone.Therefore,the oxide framework of PNb_(9)O_(25) keeps almost unchanged with all the fast diffusion channels and insertion cavities well-maintained upon cycling,which accomplishes the unconventional electrochemical performance of W-R structured electrodes.
基金NSAF joint Fund(U1830106)National Natural Science Foundation of China(U1632114,21673064)K.C.Wong Magna Fund in Ningbo University.
文摘If the operating voltage of anode materials is below 1.0 V versus Lit/Li,the side reaction between electrolyte and anode materials will occur extensively.Thus,high-voltage anode materials have aroused interest recently.In this work,we report the preparation of PNb9O25 nanofiber via a facile electrospinning method.The PNb9O25 nanofiber shows the high rate performance and excellent cycling performance when it is used as anode in lithium ions batteries.For instance,the PNb9O25 nanofiber can deliver a capacity of 233,212.1,193.8,and 181.4 mA h g^(-1) at 0.2,1,3,and 6C,respectively.After 1000 cycles,it can reach at 134.3 mA h g^(-1) with capacity retention of 70.9%.Meanwhile,the ex situ X-ray photoelectron spectroscopy technique has been adopted to investigate the evolution in valence state of each element for PNb9O25 nanofiber.In addition,the PNb9O25 nanofiber is chosen as the anode material in lithium ion full cell in this work,demonstrating the potential for practical application.
文摘The transition energies, wavelengths and oscillator strengths for the ls22s-ls2np （n≤9） transitions of Ni25＋ ion are calculated. In calculation of the energies, we not only take account of the first- order corrections from relativistic and mass-polarization effects, but also estimate the higher-order relativistic contribution and QED correction by introducing the effective nuclear charge. The results agree with experimental data available in literature satisfactorily. Grotrian diagram showing these transitions is given.
