Up to now,how the secretion modes of intestinal fluid(i.e.,pancreaticobiliary secretion and wall secretion)can regulate intestinal acid-base environment has not been fully understood.Understanding the regulation mecha...Up to now,how the secretion modes of intestinal fluid(i.e.,pancreaticobiliary secretion and wall secretion)can regulate intestinal acid-base environment has not been fully understood.Understanding the regulation mechanism is not only of great significance for intestinal health but may also lead to optimized designs for bio-inspired soft elastic reactors(SERs).In this work,the mixing and reaction of acidic gastric juice and alkaline intestinal fluid in a 3D duodenum with moving walls were modelled.A unique feature of this model is the implementation of both pancreaticobiliary and wall secretion of intestinal fluid as boundary conditions.This model allowed us to quantitatively explore the influence of secretion modes on pH regulation.The results demonstrated that coexistence of both pancreaticobiliary and wall secretions is the key to maintain the average pH in the duodenum at about 7.4.Their coexistence synergistically promotes the mixing and reaction of acid-base digestion liquids and provides a suitable catalytic environment for lipase in the intestine.展开更多
Heavy oil millisecond gas-phase in-line catalytic dehydrogenation over bifunctional catalysts was adopted to produce low-carbon olefins.In this study,the effect of the uncatalyzed reaction composition and distribution...Heavy oil millisecond gas-phase in-line catalytic dehydrogenation over bifunctional catalysts was adopted to produce low-carbon olefins.In this study,the effect of the uncatalyzed reaction composition and distribution of atmosphere residue(AR)pyrolysis vapor at 650℃ was investigated for the first time.In the pyrolysis vapor,the yield of low-carbon olefins was only 15.2%.The yield of 1-olefin and n-alkanes,which are the primary products of rapid heavy oil pyrolysis,reached approximately 54.0%.To achieve further catalytic dehydrogenation,AR pyrolysis volatiles were catalyzed over single calcium aluminate(C_(12)A_(7)),ZSM-5,and C_(12)A_(7)-ZSM-5(CZ)catalysts at 650℃,which possess different pore structures,and acid-base properties.The ZSM-5 catalyst obtained the highest low-carbon olefin yield after catalytic dehydrogenation of pyrolysis volatiles.Finally,the C_(12)A_(7) and CZ stepwise coupling bifunctional catalysts increased the catalytic activity,and thus increased the higher low-carbon olefin yield but reduced the yields of alkanes and aromatics fraction.Notably,the yields of propylene and butane were important sources of the low-carbon olefins.Thus,heavy oil millisecond gas-phase in-line catalytic dehydrogenation could achieve the maximum conversion of these residues to produce low-carbon olefins.展开更多
The nitrogen-coordinated metal single-atom catalysts(M−N−C SACs)with an ultra-high metal loading synthetized by direct high-temperature pyrolysis have been widely reported.However,most of metal single atoms in these c...The nitrogen-coordinated metal single-atom catalysts(M−N−C SACs)with an ultra-high metal loading synthetized by direct high-temperature pyrolysis have been widely reported.However,most of metal single atoms in these catalysts were buried in the carbon matrix,resulting in a low metal utilization and inaccessibility for adsorption of reactants during the catalytic process.Herein,we reported a facile synthesis based on the hard-soft acid-base(HSAB)theory to fabricate Co single-atom catalysts with highly exposed metal atoms ligated to the external pyridinic-N sites of a nitrogen-doped carbon support.Benefiting from the highly accessible Co active sites,the prepared Co−N−C SAC exhibited a superior oxygen reduction reactivity comparable to that of the commercial Pt/C catalyst,showing a high turnover frequency(TOF)of 0.93 e^(−)·s^(-1)·site^(-1)at 0.85 V vs.RHE,far exceeding those of some representative SACs with a ultra-high metal content.This work provides a rational strategy to design and prepare M−N−C single-atom catalysts featured with high site-accessibility and site-density.展开更多
Proton exchange membrane fuel cells (PEMFCs) provide an appealing sustainable energy system,with the solid-electrolyte membrane playing a crucial role in its overall performance.Currently,sulfonated poly(1,4-phenylene...Proton exchange membrane fuel cells (PEMFCs) provide an appealing sustainable energy system,with the solid-electrolyte membrane playing a crucial role in its overall performance.Currently,sulfonated poly(1,4-phenylene ether-ether sulfone)(SPEES),an aromatic hydrocarbon polymer,has garnered considerable attention as an alternative to Nafion polymers.However,the long-term durability and stability of SPEES present a significant challenge.In this context,we introduce a potential solution in the form of an additive,specifically a core–shell-based amine-functionalized iron titanate (A–Fe_(2)TiO_(5)),which holds promise for improving the lifetime,proton conductivity,and power density of SPEES in PEMFCs.The modified SPEES/A–Fe_(2)TiO_(5)composite membranes exhibited notable characteristics,including high water uptake,enhanced thermomechanical stability,and oxidative stability.Notably,the SPEES membrane loaded with 1.2 wt%of A–Fe_(2)TiO_(5)demonstrates a maximum proton conductivity of 155 mS ccm^(-1),a twofold increase compared to the SPEES membrane,at 80°C under 100%relative humidity (RH).Furthermore,the 1.2 wt%of A–Fe_(2)TiO_(5)/SPEES composite membranes exhibited a maximum power density of 397.37 mW cm^(-2)and a current density of 1148 mA cm^(-2)at 60°C under 100%RH,with an opencircuit voltage decay of 0.05 m V/h during 103 h of continuous operation.This study offers significant insights into the development and understanding of innovative SPEES nanocomposite membranes for PEMFC applications.展开更多
Lithium metal batteries,with their light mass anode and high theoretical specific capacity of 3860 m Ah/g,have great potential for development in achieving high energy density.However,the generation of lithium dendrit...Lithium metal batteries,with their light mass anode and high theoretical specific capacity of 3860 m Ah/g,have great potential for development in achieving high energy density.However,the generation of lithium dendrites and the loss of dead lithium pose a serious threat to the safety and long-cycle stability of batteries.Herein,we utilize the Lewis acid-base interaction principle for lithium-ion migration regulation.Through loading solid-acids onto molecular sieves to immobilize Lewis base(PF_(6^(-))),we achieve accelerated dissociation of lithium salts and successfully increase the lithium ion transference number to 0.44.Lewis acid-base interaction helps lithium metal batteries achieve more uniform lithium deposition,with an average CE improved to 92.8%.The symmetrical cells can be plated/stripped stably for more than 800 h of cycling.Full cell with high surface-loaded LFP cathode(14 mg/cm^(2))exhibits impressively high capacity retention of 90.7%after 120 cycles at 0.5 C.展开更多
The alkaline hydrogen evolution reaction(HER)is a crucial process for sustainable hydrogen production,yet it requires efficient and stable electrocatalysts to overcome the high activation energy barrier.The article di...The alkaline hydrogen evolution reaction(HER)is a crucial process for sustainable hydrogen production,yet it requires efficient and stable electrocatalysts to overcome the high activation energy barrier.The article discusses a novel strategy for enhancing the performance of Ni-Fe layered double hydroxide(Ni-Fe LDH)in the alkaline HER by modifying it with a frustrated Lewis acid-base pair(FLP)constructed through vacancy engineering.The study found that the modified Ni-Fe LDH exhibited improved alkaline HER performance.Density functional theory(DFT)calculations demonstrate that the introduction of FLP can activate water and protons more efficiently than monometallic sites,thus reducing the alkaline HER energy barrier and overpotential.In HER under alkaline conditions,the Volmer step involves an additional hydrolysis dissociation compared to acidic conditions,which is one of the factors contributing to the slow reaction kinetics.This paper demonstrates that FLPs can alter the rate-determining step in alkaline HER from the Volmer step to a step with a lower energy barrier,more suitable for hydrogen desorption.The work provides new insights into the role of FLPs in regulating the mechanism and kinetics of HER and opens a new direction for the design and optimization of LDH-based and other electrocatalysts.展开更多
为系统分析方正银鲫的肌肉营养品质,测定了5个方正银鲫群体的肌肉基本营养成分,以及氨基酸、脂肪酸的组成和含量,为方正银鲫的养殖推广及种质资源开发利用提供基础。结果表明:方正银鲫的水分含量为71.49%~76.63%,粗脂肪含量为2.28%~5.1...为系统分析方正银鲫的肌肉营养品质,测定了5个方正银鲫群体的肌肉基本营养成分,以及氨基酸、脂肪酸的组成和含量,为方正银鲫的养殖推广及种质资源开发利用提供基础。结果表明:方正银鲫的水分含量为71.49%~76.63%,粗脂肪含量为2.28%~5.16%,粗蛋白含量为17.36%~18.91%,属于中低脂鱼类,含有较高蛋白;17种氨基酸总量为14.02~14.95 g/100 g,必需氨基酸含量为4.65~5.10 g/100 g,呈味氨基酸含量为5.53~5.84 g/100 g,必需氨基酸评分、化学指数和必需氨基酸指数均高于联合国粮食及农业组织/世界卫生组织(Food and Agriculture Organization of the United Nations/World Health Organization,FAO/WHO)推荐比值,鲜味氨基酸占比较高;21种脂肪酸中,饱和脂肪酸在总脂肪酸中占23.77%~27.04%,多不饱和脂肪酸占32.67%~36.73%,脂肪酸组成符合中国淡水鱼的脂肪组成。综上所述,方正银鲫肌肉具有蛋白质含量高,味道鲜美等特性,能够作为人类所需营养的优质来源进行推广养殖。展开更多
Acetol is a major light oxygenate and readily produced from staged or fast pyrolysis of lignocellulose biomass. Herein we report that acetol can be selectively converted to methyl pyruvate, an important fine chemical,...Acetol is a major light oxygenate and readily produced from staged or fast pyrolysis of lignocellulose biomass. Herein we report that acetol can be selectively converted to methyl pyruvate, an important fine chemical, through oxidative esterification over Au-based catalysts. Detailed experimental studies showed that Au on amphoteric supports with appropriate strength and balanced ratio of acid and base sites can facilitate the desired oxidative-esterification pathway without accelerating undesired aldol-condensation or Cannizzaro reactions. In particular, hydroxyapatite (with a Ca/P ratio of 1.62) supported Au achieved 87% selectivity to methyl pyruvate at an acetol conversion of 62%.展开更多
As a mono-sodium salt form of alendronic acid,alendronate sodium presents multi-level ionization for the dissociation of its four hydroxyl groups.The dissociation constants of alendronate sodium were determined in thi...As a mono-sodium salt form of alendronic acid,alendronate sodium presents multi-level ionization for the dissociation of its four hydroxyl groups.The dissociation constants of alendronate sodium were determined in this work by studying the piecewise linear relationship between volume of titrant and p H value based on acidbase potentiometric titration reaction.The distribution curves of alendronate sodium were drawn according to the determined p Ka values.There were 4 dissociation constants(pKa_1=2.43,pKa_2=7.55,pKa_3=10.80,pKa_4=11.99,respectively) of alendronate sodium,and 12 existing forms,of which 4 could be ignored,existing in different p H environments.展开更多
5-Hydroxymethylfurfural(5-HMF),as a key platform compound for the conversion of biomass to various biomass-derived chemicals and biofuels,has been attracted extensive attention.In this research,using Pickering high in...5-Hydroxymethylfurfural(5-HMF),as a key platform compound for the conversion of biomass to various biomass-derived chemicals and biofuels,has been attracted extensive attention.In this research,using Pickering high internal phase emulsions(Pickering HIPEs)as template and functional metal-organic frameworks(MOFs,UiO-66-SO;H and UiO-66-NH;)/Tween 85 as co-stabilizers to synthesis the dual acid-base bifunctional macroporous polymer catalyst by one-pot process,which has excellent catalytic activity in the cascade reaction of converting cellulose to 5-HMF.The effects of the emulsion parameters including the amount of surfactant(ranging from 0.5%to 2.0%(mass)),the internal phase volume fraction(ranging from 75%to 90%)and the acid/base Pickering particles mass ratio(ranging from 0:6 to 6:0)on the morphology and catalytic performance of solid catalyst were systematically researched.The results of catalytic experiments suggested that the connected large pore size of catalyst can effectively improve the cellulose conversion,and the synergistic effect of acid and base active sites can effectively improve the 5-HMF yield.The highest 5-HMF yield,about 40.5%,can be obtained by using polymer/MOFs composite as catalyst(Poly-P12,the pore size of(53.3±11.3)μm,the acid density of 1.99 mmol·g^(-1)and the base density of 1.13 mol·g^(-1))under the optimal reaction conditions(130℃,3 h).Herein,the polymer/MOFs composite with open-cell structure was prepared by the Pickering HIPEs templating method,which provided a favorable experimental basis and theoretical reference for achieving efficient production of high addedvalue product from abundant biomass.展开更多
Objective:To improve the diagnosis and therapeutic effect of occurrence and development of hyponatremia and disorder of acid-base balance among patients with hepatic encephalopathy(HE) by elucidating the regularity an...Objective:To improve the diagnosis and therapeutic effect of occurrence and development of hyponatremia and disorder of acid-base balance among patients with hepatic encephalopathy(HE) by elucidating the regularity and mechanism,as well as its influence on prognosis.Methods:327 HE patients admitted to our hospital from January 1990 to June 2010 were enrolled.Meanwhile 316 patients hospitalized in the medical department of the same hospital were chosen as the control group.Patients in both groups were given the same methods to measure arterial blood gas parameters(pH value,PaCO2,[HCO3-],TCO2,BE and SaO2),blood biochemistry([Na+],[K+],[Cl-]),liver function,kidney function and blood glucose,serum sodium,and thereupon tocalculate the anion gap(AG) and the potential [HCO3-],and acid-base balance disorder.Results:Among the 327 HE patients,hyponatremia was found in 188 cases(57.4%),of whom 132 patients died(70.2%).While among the 316 patients in control group,68 presented with hyponatremia(21.5%),and 19 died(27.9%).The incidence and mortality were significantly different between the two groups(P<0.001).All the 327 patients presented with different degrees of acid-base balance disorder and 178 died(54.4%),in whom 164(50.2%) belonged to simple acid-base balance disorder and 74(45.1%) died,136(41.6%) were dual acid-base balance disorder and 80(58.8%) died,27(8.2%) were triple acid-base disturbance and 24(88.9%) died.Whereas in the control group only 83 patients(26.2%) were recognized as simple and dual acid-base balance disorder,and 18(21.7%) died.There was higher incidence of acid-base balance disorder and mortality rate in HE group than control one(P<0.001).Conclusion:Hyponatremia is valuable to judge HE patients' prognosis.The key parameters in the judgment and evaluation on acid-base balance disorder among HE patients are the change of pH values and serum electrolyte values.When pH value ≤ 7.30 or > 7.55,it generally suggests a poor prognosis.展开更多
Two dehydroabietic acid-based arylamines have been synthesized and characterized by FTIR, 1H NMR, 13C NMR, MS spectra and elemental analysis. Their spatial structures were determined by X-ray diffraction analysis. UV-...Two dehydroabietic acid-based arylamines have been synthesized and characterized by FTIR, 1H NMR, 13C NMR, MS spectra and elemental analysis. Their spatial structures were determined by X-ray diffraction analysis. UV-Vis absorption and fluorescence spectral characteristics of these compounds in methanol were investigated. Their fluorescence emission spectra in different polarity solvents were further evaluated. Fluorescent properties and structural relationship of the compounds showed that fluorescence intensity and quantum yield inversely increase with the non-coplanar degree. In addition, the solvent polarity has different effects on the fluorescence emission spectra of two compounds.展开更多
Cerium oxide(ceria)plays an important and fascinating role in heterogeneous catalysis as illustrated by its versatile use as a catalyst,a catalyst support,or a promotor in various oxidation and reduction reactions.Cen...Cerium oxide(ceria)plays an important and fascinating role in heterogeneous catalysis as illustrated by its versatile use as a catalyst,a catalyst support,or a promotor in various oxidation and reduction reactions.Central to these reactions is the rich defect chemistry,facile redox capability,and unusual acid-base properties of ceria.Understanding the unique redox and acid-base properties of ceria is essential to build the structure-catalysis relationship so that improved catalytic functions can be achieved for ceria-based materials.Among the characterization toolbox,spectroscopic approach indisputably stands out for its unparalleled power in offering chemical insights into the surface properties of ceria at atomic and molecular level.In this review,we summarize advances in revealing the redox and acid-base properties of ceria via a variety of spectroscopic methods including optical,X-ray,neutron,electronic and nuclear spectroscopy.Both direct spectroscopy characterization and its coupling with probe molecules are analyzed to illustrate how the nature,strength and density of different surface sites are influenced by the pretreatment,the morphology and size of ceria nanoparticles.Further directions in taking advantage of in situ/operando spectroscopy for better understanding the catalysis of ceria-based materials are proposed in the summary and outlook section.展开更多
基金the National Natural Science Foundation of China(21978184)the“Jiangsu Innovation and Entrepreneurship(Shuang Chuang)Program”,the“Jiangsu Specially-Appointed Professors Program”the“Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions”.
文摘Up to now,how the secretion modes of intestinal fluid(i.e.,pancreaticobiliary secretion and wall secretion)can regulate intestinal acid-base environment has not been fully understood.Understanding the regulation mechanism is not only of great significance for intestinal health but may also lead to optimized designs for bio-inspired soft elastic reactors(SERs).In this work,the mixing and reaction of acidic gastric juice and alkaline intestinal fluid in a 3D duodenum with moving walls were modelled.A unique feature of this model is the implementation of both pancreaticobiliary and wall secretion of intestinal fluid as boundary conditions.This model allowed us to quantitatively explore the influence of secretion modes on pH regulation.The results demonstrated that coexistence of both pancreaticobiliary and wall secretions is the key to maintain the average pH in the duodenum at about 7.4.Their coexistence synergistically promotes the mixing and reaction of acid-base digestion liquids and provides a suitable catalytic environment for lipase in the intestine.
基金the financial sponsored by the CNPC Innovation Found(No.2022DQ02-0402)the Natural Science Basic Research Program of Shaanxi(No.2024JC-YBMS-085)+2 种基金Shandong Provincial Postdoctoral Science Foundation(No.SDCX-ZG-202303044)the State Key Laboratory of Heavy Oil Processing(No.SKLHOP202201004,No.SKLHOP202403001)the Graduate Student Innovation and Practical Ability Training Program of Xi'an Shiyou University(No.YCS23213078).
文摘Heavy oil millisecond gas-phase in-line catalytic dehydrogenation over bifunctional catalysts was adopted to produce low-carbon olefins.In this study,the effect of the uncatalyzed reaction composition and distribution of atmosphere residue(AR)pyrolysis vapor at 650℃ was investigated for the first time.In the pyrolysis vapor,the yield of low-carbon olefins was only 15.2%.The yield of 1-olefin and n-alkanes,which are the primary products of rapid heavy oil pyrolysis,reached approximately 54.0%.To achieve further catalytic dehydrogenation,AR pyrolysis volatiles were catalyzed over single calcium aluminate(C_(12)A_(7)),ZSM-5,and C_(12)A_(7)-ZSM-5(CZ)catalysts at 650℃,which possess different pore structures,and acid-base properties.The ZSM-5 catalyst obtained the highest low-carbon olefin yield after catalytic dehydrogenation of pyrolysis volatiles.Finally,the C_(12)A_(7) and CZ stepwise coupling bifunctional catalysts increased the catalytic activity,and thus increased the higher low-carbon olefin yield but reduced the yields of alkanes and aromatics fraction.Notably,the yields of propylene and butane were important sources of the low-carbon olefins.Thus,heavy oil millisecond gas-phase in-line catalytic dehydrogenation could achieve the maximum conversion of these residues to produce low-carbon olefins.
基金supported by Shanxi Province Science Foundation for Youths(202203021212300)Taiyuan University of Science and Technology Scientific Research Initial Funding(20212064)Outstanding Doctoral Award Fund in Shanxi Province(20222060).
文摘The nitrogen-coordinated metal single-atom catalysts(M−N−C SACs)with an ultra-high metal loading synthetized by direct high-temperature pyrolysis have been widely reported.However,most of metal single atoms in these catalysts were buried in the carbon matrix,resulting in a low metal utilization and inaccessibility for adsorption of reactants during the catalytic process.Herein,we reported a facile synthesis based on the hard-soft acid-base(HSAB)theory to fabricate Co single-atom catalysts with highly exposed metal atoms ligated to the external pyridinic-N sites of a nitrogen-doped carbon support.Benefiting from the highly accessible Co active sites,the prepared Co−N−C SAC exhibited a superior oxygen reduction reactivity comparable to that of the commercial Pt/C catalyst,showing a high turnover frequency(TOF)of 0.93 e^(−)·s^(-1)·site^(-1)at 0.85 V vs.RHE,far exceeding those of some representative SACs with a ultra-high metal content.This work provides a rational strategy to design and prepare M−N−C single-atom catalysts featured with high site-accessibility and site-density.
基金BK21 FOUR Program by Jeonbuk National University Research Grantsupported by “Regional Innovation Strategy (RIS)” through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (MOE)(2023RIS-008)H2KOREA funded by the Ministry of Education(2024 Hydrogen Industry-002, Innovative Human Resources Development Project for Hydrogen Industry)。
文摘Proton exchange membrane fuel cells (PEMFCs) provide an appealing sustainable energy system,with the solid-electrolyte membrane playing a crucial role in its overall performance.Currently,sulfonated poly(1,4-phenylene ether-ether sulfone)(SPEES),an aromatic hydrocarbon polymer,has garnered considerable attention as an alternative to Nafion polymers.However,the long-term durability and stability of SPEES present a significant challenge.In this context,we introduce a potential solution in the form of an additive,specifically a core–shell-based amine-functionalized iron titanate (A–Fe_(2)TiO_(5)),which holds promise for improving the lifetime,proton conductivity,and power density of SPEES in PEMFCs.The modified SPEES/A–Fe_(2)TiO_(5)composite membranes exhibited notable characteristics,including high water uptake,enhanced thermomechanical stability,and oxidative stability.Notably,the SPEES membrane loaded with 1.2 wt%of A–Fe_(2)TiO_(5)demonstrates a maximum proton conductivity of 155 mS ccm^(-1),a twofold increase compared to the SPEES membrane,at 80°C under 100%relative humidity (RH).Furthermore,the 1.2 wt%of A–Fe_(2)TiO_(5)/SPEES composite membranes exhibited a maximum power density of 397.37 mW cm^(-2)and a current density of 1148 mA cm^(-2)at 60°C under 100%RH,with an opencircuit voltage decay of 0.05 m V/h during 103 h of continuous operation.This study offers significant insights into the development and understanding of innovative SPEES nanocomposite membranes for PEMFC applications.
基金supported by the National Natural Science Foundation of China(No.22179007)。
文摘Lithium metal batteries,with their light mass anode and high theoretical specific capacity of 3860 m Ah/g,have great potential for development in achieving high energy density.However,the generation of lithium dendrites and the loss of dead lithium pose a serious threat to the safety and long-cycle stability of batteries.Herein,we utilize the Lewis acid-base interaction principle for lithium-ion migration regulation.Through loading solid-acids onto molecular sieves to immobilize Lewis base(PF_(6^(-))),we achieve accelerated dissociation of lithium salts and successfully increase the lithium ion transference number to 0.44.Lewis acid-base interaction helps lithium metal batteries achieve more uniform lithium deposition,with an average CE improved to 92.8%.The symmetrical cells can be plated/stripped stably for more than 800 h of cycling.Full cell with high surface-loaded LFP cathode(14 mg/cm^(2))exhibits impressively high capacity retention of 90.7%after 120 cycles at 0.5 C.
基金financially supported by National Natural Science Foundation of China(Nos.52301011,52231008,52142304,52177220,U23A200767,52302236,and 22369005)Hainan Provincial Natural Science Foundation of China(Nos.524QN226 and 524QN222)+2 种基金the Key Research and Development Program of Hainan Province(No.ZDYF2022GXJS006)Starting Research Fund from the Hainan University(No.KYQD(ZR)23026)International Science&Technology Cooperation Program of Hainan Province(No.GHYF2023007).
文摘The alkaline hydrogen evolution reaction(HER)is a crucial process for sustainable hydrogen production,yet it requires efficient and stable electrocatalysts to overcome the high activation energy barrier.The article discusses a novel strategy for enhancing the performance of Ni-Fe layered double hydroxide(Ni-Fe LDH)in the alkaline HER by modifying it with a frustrated Lewis acid-base pair(FLP)constructed through vacancy engineering.The study found that the modified Ni-Fe LDH exhibited improved alkaline HER performance.Density functional theory(DFT)calculations demonstrate that the introduction of FLP can activate water and protons more efficiently than monometallic sites,thus reducing the alkaline HER energy barrier and overpotential.In HER under alkaline conditions,the Volmer step involves an additional hydrolysis dissociation compared to acidic conditions,which is one of the factors contributing to the slow reaction kinetics.This paper demonstrates that FLPs can alter the rate-determining step in alkaline HER from the Volmer step to a step with a lower energy barrier,more suitable for hydrogen desorption.The work provides new insights into the role of FLPs in regulating the mechanism and kinetics of HER and opens a new direction for the design and optimization of LDH-based and other electrocatalysts.
文摘为系统分析方正银鲫的肌肉营养品质,测定了5个方正银鲫群体的肌肉基本营养成分,以及氨基酸、脂肪酸的组成和含量,为方正银鲫的养殖推广及种质资源开发利用提供基础。结果表明:方正银鲫的水分含量为71.49%~76.63%,粗脂肪含量为2.28%~5.16%,粗蛋白含量为17.36%~18.91%,属于中低脂鱼类,含有较高蛋白;17种氨基酸总量为14.02~14.95 g/100 g,必需氨基酸含量为4.65~5.10 g/100 g,呈味氨基酸含量为5.53~5.84 g/100 g,必需氨基酸评分、化学指数和必需氨基酸指数均高于联合国粮食及农业组织/世界卫生组织(Food and Agriculture Organization of the United Nations/World Health Organization,FAO/WHO)推荐比值,鲜味氨基酸占比较高;21种脂肪酸中,饱和脂肪酸在总脂肪酸中占23.77%~27.04%,多不饱和脂肪酸占32.67%~36.73%,脂肪酸组成符合中国淡水鱼的脂肪组成。综上所述,方正银鲫肌肉具有蛋白质含量高,味道鲜美等特性,能够作为人类所需营养的优质来源进行推广养殖。
基金supported by the National Natural Science Foundation of China(91545114,91545203,and 21576227)the 985 Program of the Chemistry and Chemical Engineering disciplines of Xiamen University~~
文摘Acetol is a major light oxygenate and readily produced from staged or fast pyrolysis of lignocellulose biomass. Herein we report that acetol can be selectively converted to methyl pyruvate, an important fine chemical, through oxidative esterification over Au-based catalysts. Detailed experimental studies showed that Au on amphoteric supports with appropriate strength and balanced ratio of acid and base sites can facilitate the desired oxidative-esterification pathway without accelerating undesired aldol-condensation or Cannizzaro reactions. In particular, hydroxyapatite (with a Ca/P ratio of 1.62) supported Au achieved 87% selectivity to methyl pyruvate at an acetol conversion of 62%.
基金the support of Key Laboratory of Chinese Medicine Preparation of Solid Dispersion,Gansu Longshenrongfa Pharmaceutical Industry Co.,Ltd.,Gansu Province,China
文摘As a mono-sodium salt form of alendronic acid,alendronate sodium presents multi-level ionization for the dissociation of its four hydroxyl groups.The dissociation constants of alendronate sodium were determined in this work by studying the piecewise linear relationship between volume of titrant and p H value based on acidbase potentiometric titration reaction.The distribution curves of alendronate sodium were drawn according to the determined p Ka values.There were 4 dissociation constants(pKa_1=2.43,pKa_2=7.55,pKa_3=10.80,pKa_4=11.99,respectively) of alendronate sodium,and 12 existing forms,of which 4 could be ignored,existing in different p H environments.
基金financially supported by the National Natural Science Foundation of China(No.21606100)the Natural Science Foundation of Jiangsu Province(No.BK20180850)+1 种基金the China Postdoctoral Science Foundation(Nos.2019M651740 and 2019T120397)the Young Talent Cultivate Programme of Jiangsu University。
文摘5-Hydroxymethylfurfural(5-HMF),as a key platform compound for the conversion of biomass to various biomass-derived chemicals and biofuels,has been attracted extensive attention.In this research,using Pickering high internal phase emulsions(Pickering HIPEs)as template and functional metal-organic frameworks(MOFs,UiO-66-SO;H and UiO-66-NH;)/Tween 85 as co-stabilizers to synthesis the dual acid-base bifunctional macroporous polymer catalyst by one-pot process,which has excellent catalytic activity in the cascade reaction of converting cellulose to 5-HMF.The effects of the emulsion parameters including the amount of surfactant(ranging from 0.5%to 2.0%(mass)),the internal phase volume fraction(ranging from 75%to 90%)and the acid/base Pickering particles mass ratio(ranging from 0:6 to 6:0)on the morphology and catalytic performance of solid catalyst were systematically researched.The results of catalytic experiments suggested that the connected large pore size of catalyst can effectively improve the cellulose conversion,and the synergistic effect of acid and base active sites can effectively improve the 5-HMF yield.The highest 5-HMF yield,about 40.5%,can be obtained by using polymer/MOFs composite as catalyst(Poly-P12,the pore size of(53.3±11.3)μm,the acid density of 1.99 mmol·g^(-1)and the base density of 1.13 mol·g^(-1))under the optimal reaction conditions(130℃,3 h).Herein,the polymer/MOFs composite with open-cell structure was prepared by the Pickering HIPEs templating method,which provided a favorable experimental basis and theoretical reference for achieving efficient production of high addedvalue product from abundant biomass.
文摘Objective:To improve the diagnosis and therapeutic effect of occurrence and development of hyponatremia and disorder of acid-base balance among patients with hepatic encephalopathy(HE) by elucidating the regularity and mechanism,as well as its influence on prognosis.Methods:327 HE patients admitted to our hospital from January 1990 to June 2010 were enrolled.Meanwhile 316 patients hospitalized in the medical department of the same hospital were chosen as the control group.Patients in both groups were given the same methods to measure arterial blood gas parameters(pH value,PaCO2,[HCO3-],TCO2,BE and SaO2),blood biochemistry([Na+],[K+],[Cl-]),liver function,kidney function and blood glucose,serum sodium,and thereupon tocalculate the anion gap(AG) and the potential [HCO3-],and acid-base balance disorder.Results:Among the 327 HE patients,hyponatremia was found in 188 cases(57.4%),of whom 132 patients died(70.2%).While among the 316 patients in control group,68 presented with hyponatremia(21.5%),and 19 died(27.9%).The incidence and mortality were significantly different between the two groups(P<0.001).All the 327 patients presented with different degrees of acid-base balance disorder and 178 died(54.4%),in whom 164(50.2%) belonged to simple acid-base balance disorder and 74(45.1%) died,136(41.6%) were dual acid-base balance disorder and 80(58.8%) died,27(8.2%) were triple acid-base disturbance and 24(88.9%) died.Whereas in the control group only 83 patients(26.2%) were recognized as simple and dual acid-base balance disorder,and 18(21.7%) died.There was higher incidence of acid-base balance disorder and mortality rate in HE group than control one(P<0.001).Conclusion:Hyponatremia is valuable to judge HE patients' prognosis.The key parameters in the judgment and evaluation on acid-base balance disorder among HE patients are the change of pH values and serum electrolyte values.When pH value ≤ 7.30 or > 7.55,it generally suggests a poor prognosis.
基金supported by the National Natural Science Foundation of China (No. 31170539)
文摘Two dehydroabietic acid-based arylamines have been synthesized and characterized by FTIR, 1H NMR, 13C NMR, MS spectra and elemental analysis. Their spatial structures were determined by X-ray diffraction analysis. UV-Vis absorption and fluorescence spectral characteristics of these compounds in methanol were investigated. Their fluorescence emission spectra in different polarity solvents were further evaluated. Fluorescent properties and structural relationship of the compounds showed that fluorescence intensity and quantum yield inversely increase with the non-coplanar degree. In addition, the solvent polarity has different effects on the fluorescence emission spectra of two compounds.
文摘Cerium oxide(ceria)plays an important and fascinating role in heterogeneous catalysis as illustrated by its versatile use as a catalyst,a catalyst support,or a promotor in various oxidation and reduction reactions.Central to these reactions is the rich defect chemistry,facile redox capability,and unusual acid-base properties of ceria.Understanding the unique redox and acid-base properties of ceria is essential to build the structure-catalysis relationship so that improved catalytic functions can be achieved for ceria-based materials.Among the characterization toolbox,spectroscopic approach indisputably stands out for its unparalleled power in offering chemical insights into the surface properties of ceria at atomic and molecular level.In this review,we summarize advances in revealing the redox and acid-base properties of ceria via a variety of spectroscopic methods including optical,X-ray,neutron,electronic and nuclear spectroscopy.Both direct spectroscopy characterization and its coupling with probe molecules are analyzed to illustrate how the nature,strength and density of different surface sites are influenced by the pretreatment,the morphology and size of ceria nanoparticles.Further directions in taking advantage of in situ/operando spectroscopy for better understanding the catalysis of ceria-based materials are proposed in the summary and outlook section.
