Li1.3Al0.3Ti1.7(PO4)3-coated LiMn2O4 was prepared by wet chemical route. The phase,surface morphology,and electrochemical properties of the prepared powders were characterized by X-ray diffraction,scanning electron mi...Li1.3Al0.3Ti1.7(PO4)3-coated LiMn2O4 was prepared by wet chemical route. The phase,surface morphology,and electrochemical properties of the prepared powders were characterized by X-ray diffraction,scanning electron micrograph,and galvanostatic charge-discharge experiments. Li1.3Al0.3Ti1.7(PO4)3-coated LiMn2O4 has similar X-ray diffraction patterns as LiMn2O4. The corner and border of Li1.3Al0.3Ti1.7(PO4)3-coated LiMn2O4 particles are not as clear as the uncoated one. The two powders show similar values of l...展开更多
A new fluorescent ＂on-off＇ chemosensor for Hg2＋ initiated by a derivative of rhodamine B was designed and synthesized. Compound 1 exhibited high sensitivity and selectivity for Hg2＋ over other commonly coexistent ...A new fluorescent ＂on-off＇ chemosensor for Hg2＋ initiated by a derivative of rhodamine B was designed and synthesized. Compound 1 exhibited high sensitivity and selectivity for Hg2＋ over other commonly coexistent metal ions in aqueous media, Upon the addition of Hg2＋, the spirocyclic ring of probe is opened and a significant enhancement of visible color and fluorescence in the range of 500-600 nm is observed, The colorimetric and fluorescent response to Hg2＋ can be conveniently detected by the naked eye, which provides a facile method for visual detection of Hg2＋, From the molecular structure and spectral results of 1, an irreversible, hydrolysis, desulfurization reaction mechanism is proposed.展开更多
The resonance light-scattering (RLS) of human serum albumin (HSA) and bovine serum albumin (BSA) is reported for the first time, and applied to study photochemical reaction of HSA and BSA. The fact of photocrosslinkin...The resonance light-scattering (RLS) of human serum albumin (HSA) and bovine serum albumin (BSA) is reported for the first time, and applied to study photochemical reaction of HSA and BSA. The fact of photocrosslinking self-association effect in HSA and BSA solutions is identified by the enhancement of RLS. The fluorescence quenching at about 350 nm and 700 nm proves that tryptophan (Trp) residues are one of the photochemical activity sites in HSA and BSA molecules. The Rayleigh scattering (RS) spectra of HSA and BSA that were neglected in fluorescence spectra before are found at about 296 nm, 592 nm and 888 nm for the first time, and are of adventageous to studying the aggregation of HSA or BSA. The possible photochemical reaction mechanism is also proposed.展开更多
Polyesters with cyclic structures in the main chain typically possess superior mechanical and thermal properties together with chemical recyclability.Ring-opening polymerization(ROP)of bridged or fused bicyclic lacton...Polyesters with cyclic structures in the main chain typically possess superior mechanical and thermal properties together with chemical recyclability.Ring-opening polymerization(ROP)of bridged or fused bicyclic lactones is a simple,and in most cases controlled method to synthesize polyesters with alicyclic moieties in the polymer backbone.The stereochemistry of the alicyclic structures has a great effect on the polymer properties,which can be regulated by varying the polymerization conditions.Here,we report a systematic investigation on the ROP of 2-oxabicyclo[2.2.2]octan-3-one([2.2.2]VL)under different conditions.When initiated byn-butyl lithium(n-BuLi)or catalyzed by trifluoromethanesulfonic acid(TfOH)in the presence of benzyl alcohol,P[2.2.2]VLs containing all cis^(-1),4 disubstituted cyclohexane ring were obtained.However,P[2.2.2]VLs initiated by sodium methoxide(MeONa)or catalyzed by organic superbase contained both cis and trans isomeric structural units.The cis to trans transformation mechanism under these conditions was manifested,and the effect of stereochemical variations on the properties ofP[2.2.2]VLwas revealed.The stereoregularP[2.2.2]VLs,bothcisandtrans,exhibited higher crystallinity and melting temperatures(Tm)than those of the stereoirregular isomers.Finally,the degradation of P[2.2.2]VL with acid at high temperature could recover 3-cyclohexenecarboxylic acid.展开更多
The copolymerization of dibenzofuran(DBF)and 3-methylthiophene(MET)was successfully achieved electrochemically by direct anodic oxidation of the monomer mixtures in boron trifluoride diethyl etherate.The effects of ap...The copolymerization of dibenzofuran(DBF)and 3-methylthiophene(MET)was successfully achieved electrochemically by direct anodic oxidation of the monomer mixtures in boron trifluoride diethyl etherate.The effects of applied polymerization potential and the monomer concentration ratios on the copolymerization were investigated by linear sweep voltammetry and cyclic voltammetry(CV).The structure of copolymer films were investigated by UV-Vis,infrared spectroscopy,thermal analysis.As-formed novel copolymers own...展开更多
For designing batteries with high-rate and long-life, electronic/ionic transport and reaction must be unified for metal oxide electrodes. However, it remains challenging for effectively integrating the whole substrate...For designing batteries with high-rate and long-life, electronic/ionic transport and reaction must be unified for metal oxide electrodes. However, it remains challenging for effectively integrating the whole substrate/active materials/electrolyte interfaces. Herein by taking Li ion battery as example, we propose a semiconductor-electrochemistry model by which a general but novel insight has been gained into interfacial effect in batteries. Different from those traditional viewpoints, this derived model lies across from physics to electrochemistry. A reaction driving force can be expressed in terms of Fermi energy change,based on the tradeoff between electronic and ionic concentration at the reaction interfacial region. Therefore, at thermodynamic-controlled interface I of substrate/electrode, increasing contact areas can afford higher activity for active materials. Whereas at kinetically-governed interface II of electrode/electrolyte or inside active materials, it is crucial to guarantee high-reaction Li ionic concentration, with which some sufficient reaction degrees can reach.展开更多
In the present paper, the electrochemical behavior of ergosterol has been investigated by in situ circular dichroism (CD) spectroelectrochemistry with long path-length thin layer cell. E-0 (1.02V), alpha n(alpha) (0.3...In the present paper, the electrochemical behavior of ergosterol has been investigated by in situ circular dichroism (CD) spectroelectrochemistry with long path-length thin layer cell. E-0 (1.02V), alpha n(alpha) (0.302) of the electroxidation process of ergosterol were obtained from the CD spectroelectrochemical data. The mechanism of the electroxidation process of ergosterol is suggested.展开更多
Two new reagents. dimethylammonium chlorochromale adsrbed on alumina and silicagel are describe as convenient reagents for efficient oxidation of a variety of primary and secondaryalcohols. These two reagents are very...Two new reagents. dimethylammonium chlorochromale adsrbed on alumina and silicagel are describe as convenient reagents for efficient oxidation of a variety of primary and secondaryalcohols. These two reagents are very stable and call be safely used for the oxidation of alcoholscontaining double bond.展开更多
The electrodeposition of neodymium on Pt and Cu electrodes was investigated in DMSO containing NdCl3 and a small mount of water at room temperature. Cyclic voltammetry indicated that the reduction process of Nd(III) o...The electrodeposition of neodymium on Pt and Cu electrodes was investigated in DMSO containing NdCl3 and a small mount of water at room temperature. Cyclic voltammetry indicated that the reduction process of Nd(III) on the Pt cathode was complicated. The one-step reduction wave showed two steps by adding 0.3 mol/L ethylenediamine(EN). A delicate yellow, lustrous, strongly adhering film on the Cu electrode was obtained using potentiostatic electrolysis at -1.80 V (vs. aq SCE).展开更多
The electrochemical behavior of the adenosine5diphosphate(ADP) was studied in 005 molL-1 MES buffer solution(pH 585) at mercury electrode. There are no reduction and oxidation waves for the adenosine5diphosphate in th...The electrochemical behavior of the adenosine5diphosphate(ADP) was studied in 005 molL-1 MES buffer solution(pH 585) at mercury electrode. There are no reduction and oxidation waves for the adenosine5diphosphate in the range of -04-14 V(vs. Ag/AgCl). In a mixture solution of Eu3+ and ADP(Eu3+ADP=14), a reduction peak is obtained at -078 V. Comparing with the cyclic voltammograms of Eu3+ ions under the same experimental conditions, it is found that the complex of Eu3+ADP can be produced in above solutions between Eu3+ion and ADP. The complex is strongly adsorbed at mercury electrode and has the following electrode reaction mechanism: Eu3++ADPEu3+ADP+e-Eu2+-ADP.展开更多
Diacholest-13(17)-ene ozonide(1a andlb) and 4, 4-dimethyldiacholest-13 (17)-eneozonides(2a and 2b) underwent pyrolysis to afford the coressponding 17-oxo-13,14;13,17- dis14-lactones (3a and 3b)and 4.4-dimethyl-17-ox...Diacholest-13(17)-ene ozonide(1a andlb) and 4, 4-dimethyldiacholest-13 (17)-eneozonides(2a and 2b) underwent pyrolysis to afford the coressponding 17-oxo-13,14;13,17- dis14-lactones (3a and 3b)and 4.4-dimethyl-17-oxo-13,14; 13,17-disecodiacholestano-13,14-lactones(4 and 4b), respectively. The stereochemi-stry of the migratingpoups was Proven to be conserved by comparison with the Baeyer-Villiger oxidation of the corresponding 13,17-secodiacholesta-13,17-diones (5) and 4,4-dimethyl-13, 17-secodiacholesta13, 17-diones(6).展开更多
The electrochemical properties of MEH-PPV were: studied in ionic liquid([bmim](+)[PF6](-)) by cyclic voltammetry, chronoamperometry and AC impedance measurements. Both p- and n-doping of MEH-PPV were observed in the c...The electrochemical properties of MEH-PPV were: studied in ionic liquid([bmim](+)[PF6](-)) by cyclic voltammetry, chronoamperometry and AC impedance measurements. Both p- and n-doping of MEH-PPV were observed in the cyclic voltammograms, The chronoamperometric and AC impedance results indicate that the p-doping of MEH-PPV was controlled by the linear diffusion of counterions.展开更多
A flow injection chemiluminescence (CL) method for the determination of catecholamines is described which is based on their inhibition of the intensity of CL from the luminol-hypochlorite system The hypochlorite was e...A flow injection chemiluminescence (CL) method for the determination of catecholamines is described which is based on their inhibition of the intensity of CL from the luminol-hypochlorite system The hypochlorite was electrogenerated on-line by a constant current electrolysis, resulting in the elimination of the instability of the hypochlorite solution prepared from a commercial reagent of sodium hypochlorite. The detection limits are 0.6 ng/ml for dopamine, 0.8 ng/ml for adrenaline and isoprenaline. The proposed method has been successfully applied to the determination of catecholamines in pharmaceutical injections.展开更多
The insulator Na2Ta4O11 has been considered as a potential photocatalyst.However,little attention has been given to the synthesis of Na2Ta4O11 nanoparticles,let alone the growth of two-dimensional(2D)layered Na2Ta4O11...The insulator Na2Ta4O11 has been considered as a potential photocatalyst.However,little attention has been given to the synthesis of Na2Ta4O11 nanoparticles,let alone the growth of two-dimensional(2D)layered Na2Ta4O11 flake,which may bring innovative properties and promising applications.Here,the 2D thin-layer Na2Ta4O11 flake was first produced by chemical vapor deposition(CVD)method,with the smallest thickness reported currently.We have also synthesized 2D Na2Ta4O11 flake over 100μm,which was the largest value over the 2D level reported to date.Our work proposed novel strategies to synthesize other 2D metal oxide material and endow the Na2Ta4O11 more properties and applications.展开更多
Gentiana rhodantha Franch.ex Hemsl.(G.rhodantha)is a perennial herb distributed in southwest China,belonging to the Gentiana genus of Gentianaceae family.Previous research indicated that G.rhodantha contains flavonoid...Gentiana rhodantha Franch.ex Hemsl.(G.rhodantha)is a perennial herb distributed in southwest China,belonging to the Gentiana genus of Gentianaceae family.Previous research indicated that G.rhodantha contains flavonoids,anthraquinones,terpenes and other compounds,which possess the effects of antioxidant,antibacterial,and antitumor.Besides,its dry herb is used as antiphlogistic and antitussive remedy for the treatment of lung,liver,and gallbladder diseases.This review outlines the chemical constituents and biological activities of G.rhodantha,which will be useful for the further research on this plant.展开更多
Lactose milk sugar is found only in the milk of mammals. In order to understand the mechanism of oxidation of lactose, a systematic kinetic study of oxidation of lactose with photochemicaUy generated radicals was carr...Lactose milk sugar is found only in the milk of mammals. In order to understand the mechanism of oxidation of lactose, a systematic kinetic study of oxidation of lactose with photochemicaUy generated radicals was carried out. The reaction has a first order dependence on chloramine-T as well as on substrate. The reaction is catalysed by H＋ ions as well. On the basis of kinetic results and product analysis a probable mechanism were suggested.展开更多
Green and sustainable options are needed to ease the current energy and environmental crisis, and alleviate the greenhouse effect and energy shortage. As an alternative carbon–neutral synthetic fuel, ammonia shows gr...Green and sustainable options are needed to ease the current energy and environmental crisis, and alleviate the greenhouse effect and energy shortage. As an alternative carbon–neutral synthetic fuel, ammonia shows great potential due to its high energy density, non-toxic by-products, and mature related infrastructures. However, related practical applications have been severely hampered on ammoniaoxidation due to the high cost of catalysts and immature energy utilization systems. Here, we comprehensively summarized the efforts which have been made in recent years with the aim of providing a deep sight into the development and deficiencies in this territory and trying to establish a simple framework of basic knowledge for researchers. The exploration of mechanism is discussed first and then the relevant catalysts studied in recent years are summarized. Besides, the progress of direct ammonia fuel cells(DAFCs) is also presented and the challenges as well as perspectives on future developments of electrocatalysts for ammonia electro-oxidation and its practical application are provided at the end.展开更多
Alien atom was used to obtain a series of Li Fe1-xLaxPO4/C(x=0,0.002,0.005,0.01,0.015)cathode materials with the aim of investigating the influence of participation of La on the electrochemical behavior of Li Fe PO4/C...Alien atom was used to obtain a series of Li Fe1-xLaxPO4/C(x=0,0.002,0.005,0.01,0.015)cathode materials with the aim of investigating the influence of participation of La on the electrochemical behavior of Li Fe PO4/C.Combination of X-ray diffractometer,scanning electron microscope equipped with energy dispersive spectrometer and high resolution transmission electron microscope was applied.The results show that all the La-doped Li Fe PO4/C samples are olivine type crystals,La ion is sufficiently introduced into the network,and every element is well homogeneously distributed.There are many pore spaces on the surface of particles.The content of carbon in the prepared cathode materials remains 13.6%calculated by TGA/DTA curves,and the particles are wrapped by a uniformly and continuous carbon layer with the thickness of about 2 nm.Similarly,the content of Fe2P also keeps the same basically in all the cathode materials as a result of the similar ratio(2.35)of peak intensity at 36.5o and 37.1o from XRD.The increasing trend is most pronounced at doped 0.005which presents the highest initial discharge capacity of 163 mA-h/g,lowest charge transfer resistance of 5.52-,superior diffuse ability of lithium ion(10-11 cm2/s)and the best capacity retention current rate of about 93%after 50 cycles at 0.1 C.展开更多
Efficient and stable bifunctional electrocatalysts for water splitting is essential for producing hydrogen and alleviating huge energy consumption.Meanwhile,charge transfer engineering is an efficient approach to modu...Efficient and stable bifunctional electrocatalysts for water splitting is essential for producing hydrogen and alleviating huge energy consumption.Meanwhile,charge transfer engineering is an efficient approach to modulate the localized electronic properties of catalysts and tune the electrocatalytic performance.Herein,we tactfully fabricate PtFeNi alloys/NiFe layered double hydroxides(LDHs)heterostructure by an easily electrochemical way with a small amount of Pt.The experimental and theoretical results unravel that the charge transfer on the alloy clusters modulated by the defective substrates(NiFe LDHs),which synergistically optimizes the adsorption energy of the reaction intermediates.The electrocatalyst exhibits an ultra‐low overpotential of 81 and 243 mV at the current density of 100 mA cm^(–2) for hydrogen evolution and oxygen evolution,respectively.Furthermore,the overall water splitting indicates that PtFeNi alloys/NiFe LDHs presents an ultra‐low overpotential of 265 and 406 mV to reach the current density of 10 and 300 mA cm^(–2),respectively.It proves that the PtFeNi alloys/NiFe LDHs catalyst is an excellent dual‐function electrocatalyst for water splitting and promising for industrialization.This work provides a new electrochemical approach to construct the alloy heterostructure.The prepared heterostructures act as an ideal platform to investigate the charge re‐distribution behavior and to improve the electrocatalytic activity.展开更多
A now sesquiterpenoid named as celastrine was isolated from the seed oil of Celastrus flagellaris Rupr. Its structure was determined as 1 alpha ,6 beta ,8 alpha ,13-tetraacetoxy-9 alpha -benzoyloxy-beta -dihydroagarof...A now sesquiterpenoid named as celastrine was isolated from the seed oil of Celastrus flagellaris Rupr. Its structure was determined as 1 alpha ,6 beta ,8 alpha ,13-tetraacetoxy-9 alpha -benzoyloxy-beta -dihydroagarofuran by UV, IR, MS and NMR(H-1 NMR, C-13 NMR, H-1-H-1 COSY, H-1-C-13 COSY, NOESY and HMBC) spectra.展开更多
基金the National Natural Science Foundation of China (No. 20873054)the Scientific Research Fund of Hunan Provincial Education Department, China (No. 07B060).
文摘Li1.3Al0.3Ti1.7(PO4)3-coated LiMn2O4 was prepared by wet chemical route. The phase,surface morphology,and electrochemical properties of the prepared powders were characterized by X-ray diffraction,scanning electron micrograph,and galvanostatic charge-discharge experiments. Li1.3Al0.3Ti1.7(PO4)3-coated LiMn2O4 has similar X-ray diffraction patterns as LiMn2O4. The corner and border of Li1.3Al0.3Ti1.7(PO4)3-coated LiMn2O4 particles are not as clear as the uncoated one. The two powders show similar values of l...
基金financially supported by the National Natural Science Foundation of China(Nos.20972143,21375113)Program for New Century Excellent Talents in University(No.NCET-11-0950)
文摘A new fluorescent ＂on-off＇ chemosensor for Hg2＋ initiated by a derivative of rhodamine B was designed and synthesized. Compound 1 exhibited high sensitivity and selectivity for Hg2＋ over other commonly coexistent metal ions in aqueous media, Upon the addition of Hg2＋, the spirocyclic ring of probe is opened and a significant enhancement of visible color and fluorescence in the range of 500-600 nm is observed, The colorimetric and fluorescent response to Hg2＋ can be conveniently detected by the naked eye, which provides a facile method for visual detection of Hg2＋, From the molecular structure and spectral results of 1, an irreversible, hydrolysis, desulfurization reaction mechanism is proposed.
基金the National Natural Science Foundation of China ! 29961001the Foundation for Talents Striding across the Century of Guangxi
文摘The resonance light-scattering (RLS) of human serum albumin (HSA) and bovine serum albumin (BSA) is reported for the first time, and applied to study photochemical reaction of HSA and BSA. The fact of photocrosslinking self-association effect in HSA and BSA solutions is identified by the enhancement of RLS. The fluorescence quenching at about 350 nm and 700 nm proves that tryptophan (Trp) residues are one of the photochemical activity sites in HSA and BSA molecules. The Rayleigh scattering (RS) spectra of HSA and BSA that were neglected in fluorescence spectra before are found at about 296 nm, 592 nm and 888 nm for the first time, and are of adventageous to studying the aggregation of HSA or BSA. The possible photochemical reaction mechanism is also proposed.
基金financially supported by the National Natural Science Foundation of China(Nos.21871014 and 21971005)。
文摘Polyesters with cyclic structures in the main chain typically possess superior mechanical and thermal properties together with chemical recyclability.Ring-opening polymerization(ROP)of bridged or fused bicyclic lactones is a simple,and in most cases controlled method to synthesize polyesters with alicyclic moieties in the polymer backbone.The stereochemistry of the alicyclic structures has a great effect on the polymer properties,which can be regulated by varying the polymerization conditions.Here,we report a systematic investigation on the ROP of 2-oxabicyclo[2.2.2]octan-3-one([2.2.2]VL)under different conditions.When initiated byn-butyl lithium(n-BuLi)or catalyzed by trifluoromethanesulfonic acid(TfOH)in the presence of benzyl alcohol,P[2.2.2]VLs containing all cis^(-1),4 disubstituted cyclohexane ring were obtained.However,P[2.2.2]VLs initiated by sodium methoxide(MeONa)or catalyzed by organic superbase contained both cis and trans isomeric structural units.The cis to trans transformation mechanism under these conditions was manifested,and the effect of stereochemical variations on the properties ofP[2.2.2]VLwas revealed.The stereoregularP[2.2.2]VLs,bothcisandtrans,exhibited higher crystallinity and melting temperatures(Tm)than those of the stereoirregular isomers.Finally,the degradation of P[2.2.2]VL with acid at high temperature could recover 3-cyclohexenecarboxylic acid.
基金This work was financially supported by the Natural Science Foundation of China(Nos.50663001,20564001)Ministry of Education(No.2007-207058).
文摘The copolymerization of dibenzofuran(DBF)and 3-methylthiophene(MET)was successfully achieved electrochemically by direct anodic oxidation of the monomer mixtures in boron trifluoride diethyl etherate.The effects of applied polymerization potential and the monomer concentration ratios on the copolymerization were investigated by linear sweep voltammetry and cyclic voltammetry(CV).The structure of copolymer films were investigated by UV-Vis,infrared spectroscopy,thermal analysis.As-formed novel copolymers own...
基金the National Natural Science Foundation of China(51872115)Program for the Development of Science and Technology of Jilin Province(20190201309JC)+5 种基金the Fundamental Research Funds for the Central Universities(Grant no.531107051230)The Open Project Program of Wuhan National Laboratory for Optoelectronicsthe Jilin Province/Jilin University co-Construction Project-Funds for New Materials(SXGJSF2017-3,Branch-2/440050316A36)Program for JLU Science and Technology Innovative Research Team(JLUSTIRT,2017TD-09)the Fundamental Research Funds for the Central Universities,JLU“Double-First Class”Discipline for Materials Science&Engineering。
文摘For designing batteries with high-rate and long-life, electronic/ionic transport and reaction must be unified for metal oxide electrodes. However, it remains challenging for effectively integrating the whole substrate/active materials/electrolyte interfaces. Herein by taking Li ion battery as example, we propose a semiconductor-electrochemistry model by which a general but novel insight has been gained into interfacial effect in batteries. Different from those traditional viewpoints, this derived model lies across from physics to electrochemistry. A reaction driving force can be expressed in terms of Fermi energy change,based on the tradeoff between electronic and ionic concentration at the reaction interfacial region. Therefore, at thermodynamic-controlled interface I of substrate/electrode, increasing contact areas can afford higher activity for active materials. Whereas at kinetically-governed interface II of electrode/electrolyte or inside active materials, it is crucial to guarantee high-reaction Li ionic concentration, with which some sufficient reaction degrees can reach.
文摘In the present paper, the electrochemical behavior of ergosterol has been investigated by in situ circular dichroism (CD) spectroelectrochemistry with long path-length thin layer cell. E-0 (1.02V), alpha n(alpha) (0.302) of the electroxidation process of ergosterol were obtained from the CD spectroelectrochemical data. The mechanism of the electroxidation process of ergosterol is suggested.
文摘Two new reagents. dimethylammonium chlorochromale adsrbed on alumina and silicagel are describe as convenient reagents for efficient oxidation of a variety of primary and secondaryalcohols. These two reagents are very stable and call be safely used for the oxidation of alcoholscontaining double bond.
文摘The electrodeposition of neodymium on Pt and Cu electrodes was investigated in DMSO containing NdCl3 and a small mount of water at room temperature. Cyclic voltammetry indicated that the reduction process of Nd(III) on the Pt cathode was complicated. The one-step reduction wave showed two steps by adding 0.3 mol/L ethylenediamine(EN). A delicate yellow, lustrous, strongly adhering film on the Cu electrode was obtained using potentiostatic electrolysis at -1.80 V (vs. aq SCE).
文摘The electrochemical behavior of the adenosine5diphosphate(ADP) was studied in 005 molL-1 MES buffer solution(pH 585) at mercury electrode. There are no reduction and oxidation waves for the adenosine5diphosphate in the range of -04-14 V(vs. Ag/AgCl). In a mixture solution of Eu3+ and ADP(Eu3+ADP=14), a reduction peak is obtained at -078 V. Comparing with the cyclic voltammograms of Eu3+ ions under the same experimental conditions, it is found that the complex of Eu3+ADP can be produced in above solutions between Eu3+ion and ADP. The complex is strongly adsorbed at mercury electrode and has the following electrode reaction mechanism: Eu3++ADPEu3+ADP+e-Eu2+-ADP.
文摘Diacholest-13(17)-ene ozonide(1a andlb) and 4, 4-dimethyldiacholest-13 (17)-eneozonides(2a and 2b) underwent pyrolysis to afford the coressponding 17-oxo-13,14;13,17- dis14-lactones (3a and 3b)and 4.4-dimethyl-17-oxo-13,14; 13,17-disecodiacholestano-13,14-lactones(4 and 4b), respectively. The stereochemi-stry of the migratingpoups was Proven to be conserved by comparison with the Baeyer-Villiger oxidation of the corresponding 13,17-secodiacholesta-13,17-diones (5) and 4,4-dimethyl-13, 17-secodiacholesta13, 17-diones(6).
基金the NSFC(29992530-4, 69986001) and the key projects of CAS(KJ951-A1-501-01)
文摘The electrochemical properties of MEH-PPV were: studied in ionic liquid([bmim](+)[PF6](-)) by cyclic voltammetry, chronoamperometry and AC impedance measurements. Both p- and n-doping of MEH-PPV were observed in the cyclic voltammograms, The chronoamperometric and AC impedance results indicate that the p-doping of MEH-PPV was controlled by the linear diffusion of counterions.
文摘A flow injection chemiluminescence (CL) method for the determination of catecholamines is described which is based on their inhibition of the intensity of CL from the luminol-hypochlorite system The hypochlorite was electrogenerated on-line by a constant current electrolysis, resulting in the elimination of the instability of the hypochlorite solution prepared from a commercial reagent of sodium hypochlorite. The detection limits are 0.6 ng/ml for dopamine, 0.8 ng/ml for adrenaline and isoprenaline. The proposed method has been successfully applied to the determination of catecholamines in pharmaceutical injections.
基金financial support from the National Natural Science Foundation of China(Nos.21975067,21705036)Natural Science Foundation of Hunan Province,China(No.2018JJ3035)。
文摘The insulator Na2Ta4O11 has been considered as a potential photocatalyst.However,little attention has been given to the synthesis of Na2Ta4O11 nanoparticles,let alone the growth of two-dimensional(2D)layered Na2Ta4O11 flake,which may bring innovative properties and promising applications.Here,the 2D thin-layer Na2Ta4O11 flake was first produced by chemical vapor deposition(CVD)method,with the smallest thickness reported currently.We have also synthesized 2D Na2Ta4O11 flake over 100μm,which was the largest value over the 2D level reported to date.Our work proposed novel strategies to synthesize other 2D metal oxide material and endow the Na2Ta4O11 more properties and applications.
文摘Gentiana rhodantha Franch.ex Hemsl.(G.rhodantha)is a perennial herb distributed in southwest China,belonging to the Gentiana genus of Gentianaceae family.Previous research indicated that G.rhodantha contains flavonoids,anthraquinones,terpenes and other compounds,which possess the effects of antioxidant,antibacterial,and antitumor.Besides,its dry herb is used as antiphlogistic and antitussive remedy for the treatment of lung,liver,and gallbladder diseases.This review outlines the chemical constituents and biological activities of G.rhodantha,which will be useful for the further research on this plant.
文摘Lactose milk sugar is found only in the milk of mammals. In order to understand the mechanism of oxidation of lactose, a systematic kinetic study of oxidation of lactose with photochemicaUy generated radicals was carried out. The reaction has a first order dependence on chloramine-T as well as on substrate. The reaction is catalysed by H＋ ions as well. On the basis of kinetic results and product analysis a probable mechanism were suggested.
基金supported by the National Natural Science Foundation of China (Grant Nos. 21905088, 21902047, 21573066, 21825201, 2187350, and 51402100)the Provincial Natural Science Foundation of Hunan (2020JJ5045)。
文摘Green and sustainable options are needed to ease the current energy and environmental crisis, and alleviate the greenhouse effect and energy shortage. As an alternative carbon–neutral synthetic fuel, ammonia shows great potential due to its high energy density, non-toxic by-products, and mature related infrastructures. However, related practical applications have been severely hampered on ammoniaoxidation due to the high cost of catalysts and immature energy utilization systems. Here, we comprehensively summarized the efforts which have been made in recent years with the aim of providing a deep sight into the development and deficiencies in this territory and trying to establish a simple framework of basic knowledge for researchers. The exploration of mechanism is discussed first and then the relevant catalysts studied in recent years are summarized. Besides, the progress of direct ammonia fuel cells(DAFCs) is also presented and the challenges as well as perspectives on future developments of electrocatalysts for ammonia electro-oxidation and its practical application are provided at the end.
基金Supported by the National Natural Science Foundation of China(No.21175012)Ministry of Science and Technology(No.2012DFR40240)
文摘Alien atom was used to obtain a series of Li Fe1-xLaxPO4/C(x=0,0.002,0.005,0.01,0.015)cathode materials with the aim of investigating the influence of participation of La on the electrochemical behavior of Li Fe PO4/C.Combination of X-ray diffractometer,scanning electron microscope equipped with energy dispersive spectrometer and high resolution transmission electron microscope was applied.The results show that all the La-doped Li Fe PO4/C samples are olivine type crystals,La ion is sufficiently introduced into the network,and every element is well homogeneously distributed.There are many pore spaces on the surface of particles.The content of carbon in the prepared cathode materials remains 13.6%calculated by TGA/DTA curves,and the particles are wrapped by a uniformly and continuous carbon layer with the thickness of about 2 nm.Similarly,the content of Fe2P also keeps the same basically in all the cathode materials as a result of the similar ratio(2.35)of peak intensity at 36.5o and 37.1o from XRD.The increasing trend is most pronounced at doped 0.005which presents the highest initial discharge capacity of 163 mA-h/g,lowest charge transfer resistance of 5.52-,superior diffuse ability of lithium ion(10-11 cm2/s)and the best capacity retention current rate of about 93%after 50 cycles at 0.1 C.
文摘Efficient and stable bifunctional electrocatalysts for water splitting is essential for producing hydrogen and alleviating huge energy consumption.Meanwhile,charge transfer engineering is an efficient approach to modulate the localized electronic properties of catalysts and tune the electrocatalytic performance.Herein,we tactfully fabricate PtFeNi alloys/NiFe layered double hydroxides(LDHs)heterostructure by an easily electrochemical way with a small amount of Pt.The experimental and theoretical results unravel that the charge transfer on the alloy clusters modulated by the defective substrates(NiFe LDHs),which synergistically optimizes the adsorption energy of the reaction intermediates.The electrocatalyst exhibits an ultra‐low overpotential of 81 and 243 mV at the current density of 100 mA cm^(–2) for hydrogen evolution and oxygen evolution,respectively.Furthermore,the overall water splitting indicates that PtFeNi alloys/NiFe LDHs presents an ultra‐low overpotential of 265 and 406 mV to reach the current density of 10 and 300 mA cm^(–2),respectively.It proves that the PtFeNi alloys/NiFe LDHs catalyst is an excellent dual‐function electrocatalyst for water splitting and promising for industrialization.This work provides a new electrochemical approach to construct the alloy heterostructure.The prepared heterostructures act as an ideal platform to investigate the charge re‐distribution behavior and to improve the electrocatalytic activity.
文摘A now sesquiterpenoid named as celastrine was isolated from the seed oil of Celastrus flagellaris Rupr. Its structure was determined as 1 alpha ,6 beta ,8 alpha ,13-tetraacetoxy-9 alpha -benzoyloxy-beta -dihydroagarofuran by UV, IR, MS and NMR(H-1 NMR, C-13 NMR, H-1-H-1 COSY, H-1-C-13 COSY, NOESY and HMBC) spectra.
