To understand the behavior of molybdenum and tungsten extracted by tri-alkyl phosphine oxide(TRPO)from peroxide solution,the extraction mechanism was studied by slope method and Raman and FTIR spectroscopy.The empiric...To understand the behavior of molybdenum and tungsten extracted by tri-alkyl phosphine oxide(TRPO)from peroxide solution,the extraction mechanism was studied by slope method and Raman and FTIR spectroscopy.The empirical formulas of molybdenum and tungsten extraction distribution ratio(D_(Mo)and D_(W))as functions of equilibrium pH,TRPO concentration and temperature were obtained by establishing mathematical models.Furthermore,the reliability of the empirical formula was verified in the H^(+)-W-Mo-H_(2)O_(2) solution.The results indicate that the calculated values of D_(Mo)or D_(W)were consistent with the experimental values.The apparent extraction equilibrium constants of molybdenum and tungsten wereK_(Mo)^(app)=8.51×10^(3)(0.74≤pH_(e)≤1.7),K_(Mo)^(app)=99.89×10^(3)(1.7<pH_(e)≤4.62)andK_(W)^(app)=2.65×10^(3)(0.92<pH_(e)<2.16)at 20°C,respectively.The main extraction complex of molybdenum or tungsten was[H_(2)(Mo or W)_(2)O_(3)(O_(2))_(4)(H_(2)O)_(2)]·2TRPO.These empirical formulas can be used to analyze and estimate the extraction and separation of Mo and W from low molybdenum and tungsten concentration solutions.展开更多
Two-electron(2 e^(-))oxygen reduction reaction(ORR)shows great promise for on-site electrochemical synthesis of hydrogen peroxide(H_(2)O_(2)).However,it is still a great challenge to design efficient electrocatalysts ...Two-electron(2 e^(-))oxygen reduction reaction(ORR)shows great promise for on-site electrochemical synthesis of hydrogen peroxide(H_(2)O_(2)).However,it is still a great challenge to design efficient electrocatalysts for H_(2)O_(2)synthesis.To address this issue,the logical design of the active site by controlling the geometric and electronic structures is urgently desired.Therefore,using density functional theory(DFT)computations,two kinds of hybrid double-atom supported on C_(2)N nanosheet(RuCu@C_(2)N and PdCu@C_(2)N)are screened out and their H_(2)O_(2)performances are predicted.PdCu@C_(2)N exhibits higher activity for H_(2)O_(2)synthesis with a lower overpotential of 0.12 V than RuCu@C_(2)N(0.59 V),Ru_(3)Cu(110)facet(0.60 V),and PdCu(110)facet(0.54 V).In aqueous phase,the adsorbed O_(2)is further stabilized with bulk H_(2)0 and the thermodynamic rate-determining step of 2 e^(-) ORR change.The activation barrier on PdCu@C_(2)N is 0.43 eV lower than the one on RuCu@C_(2)N with 0.68 eV.PdCu@C_(2)N is near the top of 2 e^(-) ORR volcano plot,and exhibits high selectivity of H_(2)O_(2.)This work provides guidelines for designing highly effective hybrid double-atom electrocatalysts(HDACs)for H_(2)O_(2)synthesis.展开更多
The preparation of hydrogen peroxide from anthrahydroquinone by reactive extraction was investigated.The integration process of oxidation of anthrahydroquinone by air and extraction of hydrogen peroxide from the organ...The preparation of hydrogen peroxide from anthrahydroquinone by reactive extraction was investigated.The integration process of oxidation of anthrahydroquinone by air and extraction of hydrogen peroxide from the organic phase with water was carried out in a sieve plate column under pressure.The conversion of anthrahydroquinone increased with increasing pressure resulting in an increase of hydrogen peroxide concentration in the aqueous phase.However,no change in extraction efficiency of hydrogen peroxide was observed.A mathematical model for gas-liquid-liquid reactive extraction was established.In themodel,the effects of pressure and gas superficial velocity on reaction were considered.With increasing gas superficial velocity,the conversion of anthrahydroquinone increased,and the fraction of hydrogen peroxide extracted reached a plateau with a maximum of 72.94%.However,both the conversion of anthrahydroquinone and the fraction of hydrogen peroxide extracted decreased with increasing organic phase superficial velocity.展开更多
This study probed the protective effect of recombinant Lactobacillus plantarum against hydrogen peroxide(H_(2)O_(2))-induced oxidative stress in human umbilical vein endothelial cells(HUVECs).We constructed a new func...This study probed the protective effect of recombinant Lactobacillus plantarum against hydrogen peroxide(H_(2)O_(2))-induced oxidative stress in human umbilical vein endothelial cells(HUVECs).We constructed a new functional L.plantarum(NC8-pSIP409-alr-angiotensin-converting enzyme inhibitory peptide(ACEIP))with a double-gene-labeled non-resistant screen as an expression vector.A 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide(MTT)colorimetric assay was carried out to determine the cell viability of HUVEC cells following pretreatment with NC8-pSIP409-alr-ACEIP.Flow cytometry(FCM)was used to determine the apoptosis rate of HUVEC cells.Cysteinyl aspartate specific proteinase(caspase)-3/8/9 activity was also assayed and western blotting was used to determine protein expression of B-cell lymphoma 2(Bcl-2),Bcl-2-associated X protein(Bax),inducible nitric oxide synthase(iNOS),nicotinamide adenine dinucleotide phosphate oxidase 2(gp91phox),angiotensin II(AngII),and angiotensin-converting enzyme 2(ACE2),as well as corresponding indicators of oxidative stress,such as reactive oxygen species(ROS),mitochondrial membrane potential(MMP),malondialdehyde(MDA),and superoxide dismutase(SOD).NC8-pSIP409-alr-ACEIP attenuated H_(2)O_(2)-induced cell death,as determined by the MTT assay.NC8-pSIP409-alr-ACEIP reduced apoptosis of HUVEC cells by FCM.In addition,compared to the positive control,the oxidative stress index of the H_(2)O_(2)-induced HUVEC(Hy-HUVEC),which was pretreated by NC8-pSIP409-alr-ACEIP,iNOS,gp91phox,MDA,and ROS,was decreased obviously;SOD expression level was increased;caspase-3 or-9 was decreased,but caspase-8 did not change;Bcl-2/Bax ratio was increased;permeability changes of mitochondria were inhibited;and loss of transmembrane potential was prevented.Expression of the hypertension-related protein(AngII protein)in HUVEC cells protected by NC8-pSIP409-alr-ACEIP decreased and expression of ACE2 protein increased.These plantarum results suggested that NC8-pSIP409-alr-ACEIP protects against H_(2)O_(展开更多
基金support from the National Natural Science Foundation of China(No.51604304)。
文摘To understand the behavior of molybdenum and tungsten extracted by tri-alkyl phosphine oxide(TRPO)from peroxide solution,the extraction mechanism was studied by slope method and Raman and FTIR spectroscopy.The empirical formulas of molybdenum and tungsten extraction distribution ratio(D_(Mo)and D_(W))as functions of equilibrium pH,TRPO concentration and temperature were obtained by establishing mathematical models.Furthermore,the reliability of the empirical formula was verified in the H^(+)-W-Mo-H_(2)O_(2) solution.The results indicate that the calculated values of D_(Mo)or D_(W)were consistent with the experimental values.The apparent extraction equilibrium constants of molybdenum and tungsten wereK_(Mo)^(app)=8.51×10^(3)(0.74≤pH_(e)≤1.7),K_(Mo)^(app)=99.89×10^(3)(1.7<pH_(e)≤4.62)andK_(W)^(app)=2.65×10^(3)(0.92<pH_(e)<2.16)at 20°C,respectively.The main extraction complex of molybdenum or tungsten was[H_(2)(Mo or W)_(2)O_(3)(O_(2))_(4)(H_(2)O)_(2)]·2TRPO.These empirical formulas can be used to analyze and estimate the extraction and separation of Mo and W from low molybdenum and tungsten concentration solutions.
基金supported by the National Natural Science Foundation of China(Grant No 21625604,21671172,21776251,21706229 and 91934302)。
文摘Two-electron(2 e^(-))oxygen reduction reaction(ORR)shows great promise for on-site electrochemical synthesis of hydrogen peroxide(H_(2)O_(2)).However,it is still a great challenge to design efficient electrocatalysts for H_(2)O_(2)synthesis.To address this issue,the logical design of the active site by controlling the geometric and electronic structures is urgently desired.Therefore,using density functional theory(DFT)computations,two kinds of hybrid double-atom supported on C_(2)N nanosheet(RuCu@C_(2)N and PdCu@C_(2)N)are screened out and their H_(2)O_(2)performances are predicted.PdCu@C_(2)N exhibits higher activity for H_(2)O_(2)synthesis with a lower overpotential of 0.12 V than RuCu@C_(2)N(0.59 V),Ru_(3)Cu(110)facet(0.60 V),and PdCu(110)facet(0.54 V).In aqueous phase,the adsorbed O_(2)is further stabilized with bulk H_(2)0 and the thermodynamic rate-determining step of 2 e^(-) ORR change.The activation barrier on PdCu@C_(2)N is 0.43 eV lower than the one on RuCu@C_(2)N with 0.68 eV.PdCu@C_(2)N is near the top of 2 e^(-) ORR volcano plot,and exhibits high selectivity of H_(2)O_(2.)This work provides guidelines for designing highly effective hybrid double-atom electrocatalysts(HDACs)for H_(2)O_(2)synthesis.
文摘The preparation of hydrogen peroxide from anthrahydroquinone by reactive extraction was investigated.The integration process of oxidation of anthrahydroquinone by air and extraction of hydrogen peroxide from the organic phase with water was carried out in a sieve plate column under pressure.The conversion of anthrahydroquinone increased with increasing pressure resulting in an increase of hydrogen peroxide concentration in the aqueous phase.However,no change in extraction efficiency of hydrogen peroxide was observed.A mathematical model for gas-liquid-liquid reactive extraction was established.In themodel,the effects of pressure and gas superficial velocity on reaction were considered.With increasing gas superficial velocity,the conversion of anthrahydroquinone increased,and the fraction of hydrogen peroxide extracted reached a plateau with a maximum of 72.94%.However,both the conversion of anthrahydroquinone and the fraction of hydrogen peroxide extracted decreased with increasing organic phase superficial velocity.
基金This work is supported the National Key Research and Development Program of China(Nos.2017YFD0501000 and 2017YFD0501200)the National Natural Science Foundation of China(Nos.31672528,31941018,and 32072888)+1 种基金the Science and Technology Project of Jilin Provincial Department of Education(No.JJKH20190942KJ)the Science and Technology Development Program of Jilin Province(Nos.20180201040NY and 20190301042NY),China.
文摘This study probed the protective effect of recombinant Lactobacillus plantarum against hydrogen peroxide(H_(2)O_(2))-induced oxidative stress in human umbilical vein endothelial cells(HUVECs).We constructed a new functional L.plantarum(NC8-pSIP409-alr-angiotensin-converting enzyme inhibitory peptide(ACEIP))with a double-gene-labeled non-resistant screen as an expression vector.A 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide(MTT)colorimetric assay was carried out to determine the cell viability of HUVEC cells following pretreatment with NC8-pSIP409-alr-ACEIP.Flow cytometry(FCM)was used to determine the apoptosis rate of HUVEC cells.Cysteinyl aspartate specific proteinase(caspase)-3/8/9 activity was also assayed and western blotting was used to determine protein expression of B-cell lymphoma 2(Bcl-2),Bcl-2-associated X protein(Bax),inducible nitric oxide synthase(iNOS),nicotinamide adenine dinucleotide phosphate oxidase 2(gp91phox),angiotensin II(AngII),and angiotensin-converting enzyme 2(ACE2),as well as corresponding indicators of oxidative stress,such as reactive oxygen species(ROS),mitochondrial membrane potential(MMP),malondialdehyde(MDA),and superoxide dismutase(SOD).NC8-pSIP409-alr-ACEIP attenuated H_(2)O_(2)-induced cell death,as determined by the MTT assay.NC8-pSIP409-alr-ACEIP reduced apoptosis of HUVEC cells by FCM.In addition,compared to the positive control,the oxidative stress index of the H_(2)O_(2)-induced HUVEC(Hy-HUVEC),which was pretreated by NC8-pSIP409-alr-ACEIP,iNOS,gp91phox,MDA,and ROS,was decreased obviously;SOD expression level was increased;caspase-3 or-9 was decreased,but caspase-8 did not change;Bcl-2/Bax ratio was increased;permeability changes of mitochondria were inhibited;and loss of transmembrane potential was prevented.Expression of the hypertension-related protein(AngII protein)in HUVEC cells protected by NC8-pSIP409-alr-ACEIP decreased and expression of ACE2 protein increased.These plantarum results suggested that NC8-pSIP409-alr-ACEIP protects against H_(2)O_(
