Due to a high energy density,layered transition-metal oxides have gained much attention as the promising sodium-ion batteries cathodes.However,they readily suffer from multiple phase transitions during the Na extracti...Due to a high energy density,layered transition-metal oxides have gained much attention as the promising sodium-ion batteries cathodes.However,they readily suffer from multiple phase transitions during the Na extraction process,resulting in large lattice strains which are the origin of cycledstructure degradations.Here,we demonstrate that the Na-storage lattice strains of layered oxides can be reduced by pushing charge transfer on anions(O^(2-)).Specifically,the designed O3-type Ru-based model compound,which shows an increased charge transfer on anions,displays retarded O3-P3-O1 multiple phase transitions and obviously reduced lattice strains upon cycling as directly revealed by a combination of ex situ X-ray absorption spectroscopy,in situ X-ray diffraction and geometric phase analysis.Meanwhile,the stable Na-storage lattice structure leads to a superior cycling stability with an excellent capacity retention of 84%and ultralow voltage decay of 0.2 mV/cycle after 300 cycles.More broadly,our work highlights an intrinsically structure-regulation strategy to enable a stable cycling structure of layered oxides meanwhile increasing the materials’redox activity and Nadiffusion kinetics.展开更多
The reactions of anionic zirconium oxide clusters ZrxOy- with C2H6 and C4H10 are investi-gated by a time of flight mass spectrometer coupled with a laser vaporization cluster source.Hydrogen containing products Zr2O5H...The reactions of anionic zirconium oxide clusters ZrxOy- with C2H6 and C4H10 are investi-gated by a time of flight mass spectrometer coupled with a laser vaporization cluster source.Hydrogen containing products Zr2O5H- and Zr3O7H- are observed after the reaction. Den-sity functional theory calculations indicate that the hydrogen abstraction is favorable in the reaction of Zr2O5- with C2H6, which supports that the observed Zr2O5H- and Zr3O7H- are due to hydrogen atom abstraction from the alkane molecules. This work shows a newpossible pathway in the reaction of zirconium oxide cluster anions with alkane molecules.展开更多
A rapid and concentration-dependent generation of superoxide anion （·O2^-）, measured with a superoxide-specific Cypridina luciferin-derived chemiluminescent reagent, was observed when two lanthanide salts （LaC...A rapid and concentration-dependent generation of superoxide anion （·O2^-）, measured with a superoxide-specific Cypridina luciferin-derived chemiluminescent reagent, was observed when two lanthanide salts （LaCl3 and CdCl3 ） were added to tobacco （ Nicotiana tabacum） cell suspension culture. Addition of superoxide dismutase （480 U·ml^-1） and Tiron （5 μmol·L^-1） to cell culture suspension decreases the level of lanthanide cation-induced ·O2^- generation, suggesting that ·O2^- generation is extra-cellular. Pretreatment of the cell culture suspension with diphenyleneiodonium （10 and 50 μmol·L^-1 ）, quinacrine （ 1 and 5 mmol· L^-1 ） and imidazol （ 10 mmol· L^-1 ）, inhibitors of NADPH oxidase, notably inhibits the generation of superoxide induced by lanthanide cation, implying the possible involvement of activation of NADPH oxidase. In addition, addition of SHAM （1 and 5 mmol· L^-1）, azide （0.2 and 1 mmol· L^-1 ）, inhibitor of peroxidase, has no influence on ·O2^- generation.展开更多
Objectives To study the changes of nitric oxide, angiotensin Ⅱ and superoxide anion in renal artery hypertension pathogenesis. Methods Male Wistar rats weighing 256 -285g were divided into 5 groups randomly, 10 rats ...Objectives To study the changes of nitric oxide, angiotensin Ⅱ and superoxide anion in renal artery hypertension pathogenesis. Methods Male Wistar rats weighing 256 -285g were divided into 5 groups randomly, 10 rats of each group. Control group: false operation was made and routine diet was given; Ligature group: left renal artery was ligatured uncompletely and routine diet was given; Ligature + Losartan group: left renal artery was ligatured uneompletely and Losartan 20mg · kg^(-1) · d^(-1) was added in the drinking water; Ligature + L -Arg group: left renal artery was ligatured uncompletely and L -Arg 2g · kg^(-1) · d^(-1) was added in the drinking water; Ligature + L - Arg + Losartan group: left renal artery was ligatured uncompletely and L - Arg 2g· kg^(-1)· d^(-1) and Losartan 20mg · kg^(-1)· d^(-1) was added in the drinking water. Blood pressure and heart rate were measured before and at the end of the experiment. One week after ligature, blood was drawn to determine angiotensin Ⅱ, cGMP, nitric oxide, nitric oxide synthase (NOS), O_2^-, superoxide dismutase (SOD). Results Systolic blood pressure was higher in ligature group than that in control group (p <0.05), systolic blood pressure was much lower in ligature + Losartan group than that in ligature group. Heart rate did not change significantly after experiment (p > 0. 05). AngⅡ was higher in ligature group than that in control group, even much higher in ligature + Losartan group (p < 0. 01 ). There was no difference of cGMP in each group (p >. 05). The concentration of NO was lower in ligature group (p <0.05), NO was higher in ligature + L - Arg + Losartan group than that in ligature group (p <0.05). O_2^- was higher in ligature group and ligature + L - Arg group than that in control group (p < 0. 05), O_2^- was lower in ligature + Losartan group than that in ligature group (p <0. 05). The level of SOD was lower in ligature group than that in control group (p <0.05), higher in ligature + L- Arg group and ligature + L - Arg + Losartan group than that in ligature group (p <0. 05). Conclusions AngⅡ,O_2^- and NO imbalance play an important role in hypertension pathogenesis, LArg and losartan may have protective effect.展开更多
TEMPO/NaOCl/NaBr treatment significantly increased the number of negative charges on the cellulose surface.Two concentrations of NaOCl,5 and 30 mmol/g of cellulose,were used in this study.The number of carboxyl groups...TEMPO/NaOCl/NaBr treatment significantly increased the number of negative charges on the cellulose surface.Two concentrations of NaOCl,5 and 30 mmol/g of cellulose,were used in this study.The number of carboxyl groups in the two cellulosic samples oxidized using TEMPO/NaOCl/NaBr was 0.5160 and 1.8461 mmol/g of cellulose,respectively.The oxidized cellulose samples treated with 5 and 30 mmol/g NaOCl exhibited higher crystallinity,at 81.15%and 80.14%,respectively,compared to untreated cellulose,which had a crystallinity of 75.95%.The pH effect indicated that the highest adsorption capacity for methylene blue was achieved under alkaline conditions(pH 9),while the highest adsorption capacity for rhemazol yellow FG was achieved under acidic conditions.The kinetic model of TEMPO-oxidized cellulose for methylene blue and rhemazol yellow FG conformed to the pseudo-second-order model.The initial concentration parameter revealed that the isotherm model for the adsorption of methylene blue and rhemazol yellow FG by TEMPO-oxidized cellulose conformed to the Langmuir model.The dye removal efficiencies for methylene blue and rhemazol yellow FG using TEMPOoxidized cellulose(30 mmol/g)were approximately 80.17%and 59.52%,respectively.These results demonstrate that TEMPO/NaOCl/NaBr-oxidized samples can effectively separate cationic and anionic dye mixtures.Furthermore,the use of TEMPO-oxidized cellulose showed good regeneration capability,maintaining more than 95%of its adsorption capacity after 8 cycles.展开更多
Oxide semimetals exhibiting both nontrivial topological characteristics stand as exemplary parent compounds and multiple degrees of freedom,offering a promise for the realization of novel electronic states.In this wor...Oxide semimetals exhibiting both nontrivial topological characteristics stand as exemplary parent compounds and multiple degrees of freedom,offering a promise for the realization of novel electronic states.In this work,we report the structural and transport phase transition in an oxide semimetal,SrNbO_(3),achieved through effective anion doping.Notably,the resistivity increased by more than three orders of magnitude at room temperature upon nitrogendoping.The extent of electronic modulation in SrNbO_(3)is strongly correlated with misfit strain,underscoring its phase instability to both chemical doping and crystallographic symmetry variations.Using first-principles calculations,we discern that elevating the level of nitrogen doping induces an upward shift in the conductive bands of SrNbO_(3−δ)N_(δ).Consequently,a transition from a metallic state to an insulating state becomes apparent as the nitrogen concentration reaches a threshold of 1/3.This investigation shows effective anion engineering in oxide semimetals,offering pathways for manipulating their physical properties.展开更多
The growth kinetics of microarc oxidation(MAO)coatings on Ti6Al4V alloy was studied by designing an electrolyte with low PO_(4)^(3−)content and high B_(4)O_(7)^(2−)content,using scanning electron microscopy,transmissi...The growth kinetics of microarc oxidation(MAO)coatings on Ti6Al4V alloy was studied by designing an electrolyte with low PO_(4)^(3−)content and high B_(4)O_(7)^(2−)content,using scanning electron microscopy,transmission electron microscopy,X-ray diffraction,and potentiodynamic polarization.The results showed that B_(4)O_(7)^(2−)increased the spark intensity and dissolved most of the oxides at high temperatures.Then,a thicker barrier layer at the coating/substrate interface was produced,which increased the polarization resistance of the coating.PO_(4)^(3−)at a low concentration also promoted the uniform growth of the MAO coating and the formation of hat-shaped holes in the outer deposition layer.The thickness of the MAO coatings obtained in Na_(2)B_(4)O_(7) electrolytes exhibited an exponential increase with time at spark discharge stage,while that of the MAO coating obtained in phosphate–tetraborate electrolytes showed a linear trend as the PO_(4)^(3−)content increased.展开更多
Water oxidation is the bottleneck of artificial photosynthesis.Since the first ruthenium-based molecular water oxidation catalyst,the blue dimer,was reported by Meyer’ s group in 1982,catalysts based on transition me...Water oxidation is the bottleneck of artificial photosynthesis.Since the first ruthenium-based molecular water oxidation catalyst,the blue dimer,was reported by Meyer’ s group in 1982,catalysts based on transition metals have been widely employed to explore the mechanism of water oxidation.Because the oxidation of water requires harsh oxidative conditions,the stability of transition complexes under the relevant catalytic conditions has always been a challenge.In this work,we report the redox properties of a CuⅢ complex(TAML-CuⅢ] with a redox-active macrocyclic ligand(TAML) and its reactivity toward catalytic water oxidation.TAML-CuⅢ displayed a completely different electrochemical behavior from that of the TAML-CoⅢ complex previously reported by our group.TAML-CuⅢ can only be oxidized by one-electron oxidation of the ligand to form TAML·+-CuⅢand cannot achieve water activation through the ligand-centered proton-coupled electron transfer that takes place in the case of TAML-CoⅢ.The generated TAML·+-CuⅢ intermediate can undergo further oxidation and ligand hydrolysis with the assistance of borate anions,triggering the formation of a heterogeneous B/CuOx nanocatalyst Therefore,the choice of the buffer solution has a significant influence on the electrochemical behavior and stability of molecular water oxidation catalysts.展开更多
Reducing dietary cation-anion difference （DCAD） has been proved an effective way to prevent milk fever in dairy cows. Based on the similar physiological gastro-intestinal tract anatomy and metabolic process between ...Reducing dietary cation-anion difference （DCAD） has been proved an effective way to prevent milk fever in dairy cows. Based on the similar physiological gastro-intestinal tract anatomy and metabolic process between female goats and dairy cows, this study was conducted to evaluate the effects of varying DCAD on fluid acid-base status, plasma minerals concentration and anti-oxidative stress capacity of female goats. Urinary pH, plasma Ca, P and Mg; and anti-oxidative stress indices of total superoxide dismutase （T-SOD）, hydrogen peroxide （HzO2）, glutathione peroxidase （GSH-Px） and malondialdehyde （MDA） were determined to evaluate the effect. Forty-eight Guizhou black female goats （（15±1.9） mon of old, （22.3±3.75） kg of BW） were randomly allocated to 4 blocks of 12 goats each and were fed 1 of 4 diets differed in DCAD level （calculated as Na＋K-C1-S, mEq kg-1 DM）. Levels of DCAD were preliminarily designed to be control （＋ 150 mEq kg^-1 DM, CON）, high DCAD （＋300 mEq kg^-1 DM, HD）, low DCAD （0 mEq kg^-1 DM, LD） and negative DCAD （-150 mEq kg^-1 DM, ND）, respectively. A commercial anionic salts （Animate） and sodium bicarbonate （NaHCO3） were supplemented to reduce and increase DCAD level, respectively. There was no difference in dry matter intake for 4 groups of goats. Urine pH was aggressively decreased （P〈0.0001） with reduced DCAD and there was a strong association between DCAD and urine pH （R2=0.793, P〈0.0001）. Compared with CON and HD feeding of LD and ND resulted in greater （P〈0.05） plasma Ca concentration. Plasma P level was increased （P〈0.05） when anionic salts were supplemented. The DCAD alteration did not affected （P〉0.05） plasma Mg level. There was no significant （P〉0.05） difference in plasma GSH-Px activity and H202, but anionic salts supplementation in LD and ND significantly increased （P〈0.05） plasma T-SOD activity and tended to reduce MDA （P〈0.1） over HD and CON. Results from this study indicated that reducing DCAD could decrease urine pH and increase plasma Ca concentration of female goats. Additionally, reducing DCAD was helpful to enhance anti-oxidative stress capability of female goats.展开更多
The surface oxidation of silicon （Si） wafers by atomic oxygen radical anions （O- anions） and the preparation of metal-oxide-semiconductor （MOS） capacitors on the O-oxidized Si substrates have been examined for t...The surface oxidation of silicon （Si） wafers by atomic oxygen radical anions （O- anions） and the preparation of metal-oxide-semiconductor （MOS） capacitors on the O-oxidized Si substrates have been examined for the first time. The O- anions are generated from a recently developed O- storage-emission material of [Ca24Al2sO64]^4＋·4O^- （Cl2A7-O^- for short）. After it has been irradiated by an O- anion bean： （0.5 μA/cm^2） at 300℃ for 1-10 hours, the Si wafer achieves an oxide layer with a thickness ranging from 8 to 32 nm. X-ray photoelectron spectroscopy （XPS） results reveal that the oxide layer is of a mixture of SiO2, Si2 O3, and Si2O distributed in different oxidation depths. The features of the MOS capacitor of 〈Al electrode/SiOx/Si〉 are investigated by measuring capacitance-voltage （C - V） and current-voltage （I - V） curves. The oxide charge density is about 6.0 × 10^1 cm^-2 derived from the （C - V curves. The leakage current density is in the order of 10^-6 A/cm^2 below 4 MV/cm, obtained from the I - V curves. The O- anions formed by present method would have potential applications to the oxidation and the surface-modification of materials together with the preparation of semiconductor devices.展开更多
Background: To investigate the effects of unsafe decompression on rat pulmonary endothelial function and its relevant mechanisms.Methods: Sixty male Sprague-Dawley(SD) rats were randomly divided into a control group(n...Background: To investigate the effects of unsafe decompression on rat pulmonary endothelial function and its relevant mechanisms.Methods: Sixty male Sprague-Dawley(SD) rats were randomly divided into a control group(n=30) and a decompression sickness(DCS) group(n=30). The DCS model was established by placing the rats in the DCS group in a pressurized cabin where they were exposed to a 600 k Pa compressed air environment for 60 min, and the pressure was then reduced by 100 k Pa/min until it reached atmospheric pressure. After the surviving rats in the DCS group and the rats in the control group were anesthetized, their pulmonary arteries were stripped to test the in vitro pulmonary artery endothelium-dependent vasodilation capacity. Western blotting was used to measure the expression and dissociation of endothelial nitric oxide synthase(e NOS) in pulmonary artery tissues and all protein nitration levels in pulmonary artery tissues; reactive oxygen species(ROS) formation was measured via in vitro pulmonary artery superoxide anion probe dihydroethidium(DHE) staining.Results: After experiencing unsafe decompression, 10 of the 30 rats in the DCS group died. The pulmonary artery endothelium-dependent vasodilation capacity in the surviving rats decreased significantly(P<0.05). The difference in e NOS expression between the DCS group and the control group was statistically insignificant(P>0.05), but the ratio of e NOS monomer/dimer in the DCS group was significantly higher than that in the control group(P<0.05). All protein tyrosine nitration levels in the pulmonary artery tissues of the DCS group were significantly higher than those of the control group(P<0.05). The results of DHE staining showed that the amount of ROS formation in the pulmonary arteries of the DCS group was significantly higher than that of the control group(P<0.05).Conclusion: Unsafe decompression during a simulated submarine escape process can lead to e NOS dimer uncoupling in the pulmonary artery endothelium. The dissociated e NOS monomer cannot synthesize nitric oxide(NO) and thus affect the endothelium-dependent vasodilation capacity. The e NOS monomer can promote peroxynitrite(ONOO–) synthesis, leading to an increase in protein tyrosine nitration levels in pulmonary artery tissues and causing disorder in cell cycle regulation. The e NOS monomer can also cause an increase in the formation of ROS and thus mediate peroxidation damage.展开更多
There are growing evidences on the role of adaptive mechanisms of all cell types in pathological processes: atherosclerosis, ischemic attack, bacterial infections, etc. All kinds of these processes involve as main mec...There are growing evidences on the role of adaptive mechanisms of all cell types in pathological processes: atherosclerosis, ischemic attack, bacterial infections, etc. All kinds of these processes involve as main mechanism oxidative stress. Aerobic organisms use oxygen in processes that accidentally or deliberately generate aggressive species for the biologic components in the form of radicals. Radicals were looked initially as “harmful” molecules and this is true for large quantities but in small or even moderate amounts these molecules prove to have a physiological role. Reactive species are highly reactive and as a consequence are short living species. Their impact is supposed to be limited in the proximity area of their formation. Instead recent evidences indicate their implications in cellular signaling suggesting that individual chemical properties of reactive species make a difference in their biological role. This paper presents superoxide, nitric oxide and peroxide radical generation under cellular changing conditions, the adapting behavior of the enzymes that synthesize and remove them as well as some therapeutic target in superoxide related pathology.展开更多
Anionic redox reaction(ARR) in layered manganese-based oxide cathodes has been considered as an effective strategy to improve the energy density of sodium-ion batteries.Mn-vacancy layered oxides deliver a high ARR-rel...Anionic redox reaction(ARR) in layered manganese-based oxide cathodes has been considered as an effective strategy to improve the energy density of sodium-ion batteries.Mn-vacancy layered oxides deliver a high ARR-related capacity with small voltage hysteresis,however,they are limited by rapid capacity degradation and poor rate capability,which arise from inferior structure changes due to repeated redox of lattice oxygen.Herein,redox-inactive Ti^(4+)is introduced to substitute partial Mn^(4+)to form Na_(2) Ti_(0.5)Mn_(2.5)O_7(Na_(4/7)[□_(1/7)Ti_(1/7)Mn_(5/7)]O_(2),□ for Mn vacancies),which can effectively restrain unfavorable interlayer gliding of Na2 Mn307 at high charge voltages,as reflected by an ultralow-strain volume variation of 0.11%.There is no irreversible O_(2) evolution observed in Na_(2) Ti_(0.5)Mn_(2.5)O_7 upon charging,which stabilizes the lattice oxygen and ensures the overall structural stability.It exhibits increased capacity retention of 79.1% after 60 cycles in Na_(2) Ti_(0.5)Mn_(2.5)O_7(17.1% in Na_(2) Mn_(3) O_7) and good rate capability(92.1 mAh g^(-1) at 0.5 A g^(-1)).This investigation provides new insights into designing high-performance cathode materials with reversible ARR and structural stability for SIBs.展开更多
Well - defined diblock copolymers Of styrene (St ) and ethylene oxide (EO )have been prepared by sequential living anionic polymerization of the twocomonomers in THF. Diphenyl methyl potassium has been used as initiat...Well - defined diblock copolymers Of styrene (St ) and ethylene oxide (EO )have been prepared by sequential living anionic polymerization of the twocomonomers in THF. Diphenyl methyl potassium has been used as initiator. Theblock copolymers were characterized in detail by methods Of size exclusion chromatography (SEC ) , 1H - Nab, FT - IR, dynamic mechanical analysis(Daal ) and WAXD.展开更多
Pyrite is widely distributed in estuarine sediments as an inexpensive natural Fenton-like reagent,however,the mechanism on the hydroxyl radical(HO^(·))production by pyrite under estuarine environmental conditions...Pyrite is widely distributed in estuarine sediments as an inexpensive natural Fenton-like reagent,however,the mechanism on the hydroxyl radical(HO^(·))production by pyrite under estuarine environmental conditions is still poorly understood.The batch experiments were performed to investigate the effects of estuarine conditions including aging(in air,in water),seawater anions(Cl^(-),Br^(-)and HCO_(3)^(-))and light on the HO^(·)production by pyrite oxidation.The one-electron transfer dominated the process from O_(2) to HO^(·)induced by oxidation of pyrite.The Fe(oxyhydr)oxide coatings on the surface of pyrite aged in air and water consumed hydrogen peroxide while mediating the electron transfer,and the combined effect of the two resulted in a suppression of HO^(·)production in the early stage of aging and a promotion of HO^(·)production in the later stage of aging.Corrosion of the surface oxide layers by aggressive anions was the main reason for the inhibition of HO^(·)production by Cl^(-)and Br^(-),and the generation of Cl^(·)and Br^(·)may also play a role in the scavenging of HO^(·).HCO_(3)^(-)increased the average rate of HO^(·)production through surface-CO_(2) complexes formed by adsorption on the surface of pyrite.The significant enhancement of HO^(·)production under light was attributed to the formation of photoelectrons induced by photochemical reactions on pyrite and its surface oxide layers.These findings provide new insights into the environmental chemical behavior of pyrite in the estuary and enrich the understanding of natural remediation of estuarine environments.展开更多
Fluoride is an impurity in nickel sulfate production,which is required for electric vehicle batteries.Hydrous zirconium oxide(HZO)was evaluated for removing fl uoride from nickel sulfate solution.Maximum fluoride remo...Fluoride is an impurity in nickel sulfate production,which is required for electric vehicle batteries.Hydrous zirconium oxide(HZO)was evaluated for removing fl uoride from nickel sulfate solution.Maximum fluoride removal occurred at pH value 4 and optimal pH value is 4–5,considering Zr solubility.Fluoride availability decreases with pH due to hydrogen fluoride and zirconium fluoride aqueous species.Fluoride removal is initially rapid,with 50 wt.%removal in 7 min,followed by slow removal up to 68 wt.%after 72 h and follows second order rate kinetics.Fluoride removal was dominated by an ion exchange mechanism and resulting Zr–F bonds were observed using Fourier-transform infrared spectroscopy.The presence of nickel sulfate decreased loading capacity compared to a salt-free solution.HZO maintained adsorption capacity through five cycles of loading and regeneration.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.12105197 and 52088101)Guangdong Basic and Applied Basic Research Foundation(Grant No.2022A1515010319)+1 种基金the open research fund of Songshan Lake Materials Laboratory(No.2022SLABFK04)Large Scientific Facility Open Subject of Songshan Lake,Dongguan,Guangdong
文摘Due to a high energy density,layered transition-metal oxides have gained much attention as the promising sodium-ion batteries cathodes.However,they readily suffer from multiple phase transitions during the Na extraction process,resulting in large lattice strains which are the origin of cycledstructure degradations.Here,we demonstrate that the Na-storage lattice strains of layered oxides can be reduced by pushing charge transfer on anions(O^(2-)).Specifically,the designed O3-type Ru-based model compound,which shows an increased charge transfer on anions,displays retarded O3-P3-O1 multiple phase transitions and obviously reduced lattice strains upon cycling as directly revealed by a combination of ex situ X-ray absorption spectroscopy,in situ X-ray diffraction and geometric phase analysis.Meanwhile,the stable Na-storage lattice structure leads to a superior cycling stability with an excellent capacity retention of 84%and ultralow voltage decay of 0.2 mV/cycle after 300 cycles.More broadly,our work highlights an intrinsically structure-regulation strategy to enable a stable cycling structure of layered oxides meanwhile increasing the materials’redox activity and Nadiffusion kinetics.
基金This work was supported by the Chinese Academy of Sciences （Hundred Talents Fund）, the National Natural Science Foundation of China （No.20703048 and No.20803083）, and the Center of Molecular Science Foundation of Institute of Chemistry, Chinese Academy of Sciences （No.CMS-LX200902）.
文摘The reactions of anionic zirconium oxide clusters ZrxOy- with C2H6 and C4H10 are investi-gated by a time of flight mass spectrometer coupled with a laser vaporization cluster source.Hydrogen containing products Zr2O5H- and Zr3O7H- are observed after the reaction. Den-sity functional theory calculations indicate that the hydrogen abstraction is favorable in the reaction of Zr2O5- with C2H6, which supports that the observed Zr2O5H- and Zr3O7H- are due to hydrogen atom abstraction from the alkane molecules. This work shows a newpossible pathway in the reaction of zirconium oxide cluster anions with alkane molecules.
文摘A rapid and concentration-dependent generation of superoxide anion （·O2^-）, measured with a superoxide-specific Cypridina luciferin-derived chemiluminescent reagent, was observed when two lanthanide salts （LaCl3 and CdCl3 ） were added to tobacco （ Nicotiana tabacum） cell suspension culture. Addition of superoxide dismutase （480 U·ml^-1） and Tiron （5 μmol·L^-1） to cell culture suspension decreases the level of lanthanide cation-induced ·O2^- generation, suggesting that ·O2^- generation is extra-cellular. Pretreatment of the cell culture suspension with diphenyleneiodonium （10 and 50 μmol·L^-1 ）, quinacrine （ 1 and 5 mmol· L^-1 ） and imidazol （ 10 mmol· L^-1 ）, inhibitors of NADPH oxidase, notably inhibits the generation of superoxide induced by lanthanide cation, implying the possible involvement of activation of NADPH oxidase. In addition, addition of SHAM （1 and 5 mmol· L^-1）, azide （0.2 and 1 mmol· L^-1 ）, inhibitor of peroxidase, has no influence on ·O2^- generation.
文摘Objectives To study the changes of nitric oxide, angiotensin Ⅱ and superoxide anion in renal artery hypertension pathogenesis. Methods Male Wistar rats weighing 256 -285g were divided into 5 groups randomly, 10 rats of each group. Control group: false operation was made and routine diet was given; Ligature group: left renal artery was ligatured uncompletely and routine diet was given; Ligature + Losartan group: left renal artery was ligatured uneompletely and Losartan 20mg · kg^(-1) · d^(-1) was added in the drinking water; Ligature + L -Arg group: left renal artery was ligatured uncompletely and L -Arg 2g · kg^(-1) · d^(-1) was added in the drinking water; Ligature + L - Arg + Losartan group: left renal artery was ligatured uncompletely and L - Arg 2g· kg^(-1)· d^(-1) and Losartan 20mg · kg^(-1)· d^(-1) was added in the drinking water. Blood pressure and heart rate were measured before and at the end of the experiment. One week after ligature, blood was drawn to determine angiotensin Ⅱ, cGMP, nitric oxide, nitric oxide synthase (NOS), O_2^-, superoxide dismutase (SOD). Results Systolic blood pressure was higher in ligature group than that in control group (p <0.05), systolic blood pressure was much lower in ligature + Losartan group than that in ligature group. Heart rate did not change significantly after experiment (p > 0. 05). AngⅡ was higher in ligature group than that in control group, even much higher in ligature + Losartan group (p < 0. 01 ). There was no difference of cGMP in each group (p >. 05). The concentration of NO was lower in ligature group (p <0.05), NO was higher in ligature + L - Arg + Losartan group than that in ligature group (p <0.05). O_2^- was higher in ligature group and ligature + L - Arg group than that in control group (p < 0. 05), O_2^- was lower in ligature + Losartan group than that in ligature group (p <0. 05). The level of SOD was lower in ligature group than that in control group (p <0.05), higher in ligature + L- Arg group and ligature + L - Arg + Losartan group than that in ligature group (p <0. 05). Conclusions AngⅡ,O_2^- and NO imbalance play an important role in hypertension pathogenesis, LArg and losartan may have protective effect.
文摘TEMPO/NaOCl/NaBr treatment significantly increased the number of negative charges on the cellulose surface.Two concentrations of NaOCl,5 and 30 mmol/g of cellulose,were used in this study.The number of carboxyl groups in the two cellulosic samples oxidized using TEMPO/NaOCl/NaBr was 0.5160 and 1.8461 mmol/g of cellulose,respectively.The oxidized cellulose samples treated with 5 and 30 mmol/g NaOCl exhibited higher crystallinity,at 81.15%and 80.14%,respectively,compared to untreated cellulose,which had a crystallinity of 75.95%.The pH effect indicated that the highest adsorption capacity for methylene blue was achieved under alkaline conditions(pH 9),while the highest adsorption capacity for rhemazol yellow FG was achieved under acidic conditions.The kinetic model of TEMPO-oxidized cellulose for methylene blue and rhemazol yellow FG conformed to the pseudo-second-order model.The initial concentration parameter revealed that the isotherm model for the adsorption of methylene blue and rhemazol yellow FG by TEMPO-oxidized cellulose conformed to the Langmuir model.The dye removal efficiencies for methylene blue and rhemazol yellow FG using TEMPOoxidized cellulose(30 mmol/g)were approximately 80.17%and 59.52%,respectively.These results demonstrate that TEMPO/NaOCl/NaBr-oxidized samples can effectively separate cationic and anionic dye mixtures.Furthermore,the use of TEMPO-oxidized cellulose showed good regeneration capability,maintaining more than 95%of its adsorption capacity after 8 cycles.
基金CAS Project for Young Scientists in Basic Research,Grant/Award Number:YSBR‐084China Postdoctoral Science Foundation,Grant/Award Number:2022M723353+4 种基金Jiangsu Funding Program for Excellent Postdoctoral TalentStrategic Priority Research Program(B)of the Chinese Academy of Sciences,Grant/Award Number:XDB33030200National Natural Science Foundation of China,Grant/Award Numbers:11974390,U22A20263,52250308,12347185National Key Basic Research Program of China,Grant/Award Numbers:2020YFA0309100,2019YFA0308500Postdoctoral Fellowship Program of CPSF,Grant/Award Number:GZC20230443。
文摘Oxide semimetals exhibiting both nontrivial topological characteristics stand as exemplary parent compounds and multiple degrees of freedom,offering a promise for the realization of novel electronic states.In this work,we report the structural and transport phase transition in an oxide semimetal,SrNbO_(3),achieved through effective anion doping.Notably,the resistivity increased by more than three orders of magnitude at room temperature upon nitrogendoping.The extent of electronic modulation in SrNbO_(3)is strongly correlated with misfit strain,underscoring its phase instability to both chemical doping and crystallographic symmetry variations.Using first-principles calculations,we discern that elevating the level of nitrogen doping induces an upward shift in the conductive bands of SrNbO_(3−δ)N_(δ).Consequently,a transition from a metallic state to an insulating state becomes apparent as the nitrogen concentration reaches a threshold of 1/3.This investigation shows effective anion engineering in oxide semimetals,offering pathways for manipulating their physical properties.
文摘The growth kinetics of microarc oxidation(MAO)coatings on Ti6Al4V alloy was studied by designing an electrolyte with low PO_(4)^(3−)content and high B_(4)O_(7)^(2−)content,using scanning electron microscopy,transmission electron microscopy,X-ray diffraction,and potentiodynamic polarization.The results showed that B_(4)O_(7)^(2−)increased the spark intensity and dissolved most of the oxides at high temperatures.Then,a thicker barrier layer at the coating/substrate interface was produced,which increased the polarization resistance of the coating.PO_(4)^(3−)at a low concentration also promoted the uniform growth of the MAO coating and the formation of hat-shaped holes in the outer deposition layer.The thickness of the MAO coatings obtained in Na_(2)B_(4)O_(7) electrolytes exhibited an exponential increase with time at spark discharge stage,while that of the MAO coating obtained in phosphate–tetraborate electrolytes showed a linear trend as the PO_(4)^(3−)content increased.
文摘Water oxidation is the bottleneck of artificial photosynthesis.Since the first ruthenium-based molecular water oxidation catalyst,the blue dimer,was reported by Meyer’ s group in 1982,catalysts based on transition metals have been widely employed to explore the mechanism of water oxidation.Because the oxidation of water requires harsh oxidative conditions,the stability of transition complexes under the relevant catalytic conditions has always been a challenge.In this work,we report the redox properties of a CuⅢ complex(TAML-CuⅢ] with a redox-active macrocyclic ligand(TAML) and its reactivity toward catalytic water oxidation.TAML-CuⅢ displayed a completely different electrochemical behavior from that of the TAML-CoⅢ complex previously reported by our group.TAML-CuⅢ can only be oxidized by one-electron oxidation of the ligand to form TAML·+-CuⅢand cannot achieve water activation through the ligand-centered proton-coupled electron transfer that takes place in the case of TAML-CoⅢ.The generated TAML·+-CuⅢ intermediate can undergo further oxidation and ligand hydrolysis with the assistance of borate anions,triggering the formation of a heterogeneous B/CuOx nanocatalyst Therefore,the choice of the buffer solution has a significant influence on the electrochemical behavior and stability of molecular water oxidation catalysts.
基金funded by the National Natural Science Foundation of China (30901038, 31160468)the State Key Laboratory of Animal Nutrition, Ministry of Science and Technology, China (2004DA125184F1115)the Key Technology Research and Development Program of Guizhou Province, China ([2009]3085)
文摘Reducing dietary cation-anion difference （DCAD） has been proved an effective way to prevent milk fever in dairy cows. Based on the similar physiological gastro-intestinal tract anatomy and metabolic process between female goats and dairy cows, this study was conducted to evaluate the effects of varying DCAD on fluid acid-base status, plasma minerals concentration and anti-oxidative stress capacity of female goats. Urinary pH, plasma Ca, P and Mg; and anti-oxidative stress indices of total superoxide dismutase （T-SOD）, hydrogen peroxide （HzO2）, glutathione peroxidase （GSH-Px） and malondialdehyde （MDA） were determined to evaluate the effect. Forty-eight Guizhou black female goats （（15±1.9） mon of old, （22.3±3.75） kg of BW） were randomly allocated to 4 blocks of 12 goats each and were fed 1 of 4 diets differed in DCAD level （calculated as Na＋K-C1-S, mEq kg-1 DM）. Levels of DCAD were preliminarily designed to be control （＋ 150 mEq kg^-1 DM, CON）, high DCAD （＋300 mEq kg^-1 DM, HD）, low DCAD （0 mEq kg^-1 DM, LD） and negative DCAD （-150 mEq kg^-1 DM, ND）, respectively. A commercial anionic salts （Animate） and sodium bicarbonate （NaHCO3） were supplemented to reduce and increase DCAD level, respectively. There was no difference in dry matter intake for 4 groups of goats. Urine pH was aggressively decreased （P〈0.0001） with reduced DCAD and there was a strong association between DCAD and urine pH （R2=0.793, P〈0.0001）. Compared with CON and HD feeding of LD and ND resulted in greater （P〈0.05） plasma Ca concentration. Plasma P level was increased （P〈0.05） when anionic salts were supplemented. The DCAD alteration did not affected （P〉0.05） plasma Mg level. There was no significant （P〉0.05） difference in plasma GSH-Px activity and H202, but anionic salts supplementation in LD and ND significantly increased （P〈0.05） plasma T-SOD activity and tended to reduce MDA （P〈0.1） over HD and CON. Results from this study indicated that reducing DCAD could decrease urine pH and increase plasma Ca concentration of female goats. Additionally, reducing DCAD was helpful to enhance anti-oxidative stress capability of female goats.
基金Project supported by the National Natural Science Foundation of China (Grant No 50772107)the National High Technology Development Program of China (Grant No 2006AA05Z118)
文摘The surface oxidation of silicon （Si） wafers by atomic oxygen radical anions （O- anions） and the preparation of metal-oxide-semiconductor （MOS） capacitors on the O-oxidized Si substrates have been examined for the first time. The O- anions are generated from a recently developed O- storage-emission material of [Ca24Al2sO64]^4＋·4O^- （Cl2A7-O^- for short）. After it has been irradiated by an O- anion bean： （0.5 μA/cm^2） at 300℃ for 1-10 hours, the Si wafer achieves an oxide layer with a thickness ranging from 8 to 32 nm. X-ray photoelectron spectroscopy （XPS） results reveal that the oxide layer is of a mixture of SiO2, Si2 O3, and Si2O distributed in different oxidation depths. The features of the MOS capacitor of 〈Al electrode/SiOx/Si〉 are investigated by measuring capacitance-voltage （C - V） and current-voltage （I - V） curves. The oxide charge density is about 6.0 × 10^1 cm^-2 derived from the （C - V curves. The leakage current density is in the order of 10^-6 A/cm^2 below 4 MV/cm, obtained from the I - V curves. The O- anions formed by present method would have potential applications to the oxidation and the surface-modification of materials together with the preparation of semiconductor devices.
基金supported by the Army on the Subject of China (10ZYZ219)
文摘Background: To investigate the effects of unsafe decompression on rat pulmonary endothelial function and its relevant mechanisms.Methods: Sixty male Sprague-Dawley(SD) rats were randomly divided into a control group(n=30) and a decompression sickness(DCS) group(n=30). The DCS model was established by placing the rats in the DCS group in a pressurized cabin where they were exposed to a 600 k Pa compressed air environment for 60 min, and the pressure was then reduced by 100 k Pa/min until it reached atmospheric pressure. After the surviving rats in the DCS group and the rats in the control group were anesthetized, their pulmonary arteries were stripped to test the in vitro pulmonary artery endothelium-dependent vasodilation capacity. Western blotting was used to measure the expression and dissociation of endothelial nitric oxide synthase(e NOS) in pulmonary artery tissues and all protein nitration levels in pulmonary artery tissues; reactive oxygen species(ROS) formation was measured via in vitro pulmonary artery superoxide anion probe dihydroethidium(DHE) staining.Results: After experiencing unsafe decompression, 10 of the 30 rats in the DCS group died. The pulmonary artery endothelium-dependent vasodilation capacity in the surviving rats decreased significantly(P<0.05). The difference in e NOS expression between the DCS group and the control group was statistically insignificant(P>0.05), but the ratio of e NOS monomer/dimer in the DCS group was significantly higher than that in the control group(P<0.05). All protein tyrosine nitration levels in the pulmonary artery tissues of the DCS group were significantly higher than those of the control group(P<0.05). The results of DHE staining showed that the amount of ROS formation in the pulmonary arteries of the DCS group was significantly higher than that of the control group(P<0.05).Conclusion: Unsafe decompression during a simulated submarine escape process can lead to e NOS dimer uncoupling in the pulmonary artery endothelium. The dissociated e NOS monomer cannot synthesize nitric oxide(NO) and thus affect the endothelium-dependent vasodilation capacity. The e NOS monomer can promote peroxynitrite(ONOO–) synthesis, leading to an increase in protein tyrosine nitration levels in pulmonary artery tissues and causing disorder in cell cycle regulation. The e NOS monomer can also cause an increase in the formation of ROS and thus mediate peroxidation damage.
文摘There are growing evidences on the role of adaptive mechanisms of all cell types in pathological processes: atherosclerosis, ischemic attack, bacterial infections, etc. All kinds of these processes involve as main mechanism oxidative stress. Aerobic organisms use oxygen in processes that accidentally or deliberately generate aggressive species for the biologic components in the form of radicals. Radicals were looked initially as “harmful” molecules and this is true for large quantities but in small or even moderate amounts these molecules prove to have a physiological role. Reactive species are highly reactive and as a consequence are short living species. Their impact is supposed to be limited in the proximity area of their formation. Instead recent evidences indicate their implications in cellular signaling suggesting that individual chemical properties of reactive species make a difference in their biological role. This paper presents superoxide, nitric oxide and peroxide radical generation under cellular changing conditions, the adapting behavior of the enzymes that synthesize and remove them as well as some therapeutic target in superoxide related pathology.
基金Financial supports from the National Natural Science Foundation of China (21822506 and 51761165025)the Tianjin Natural Science Foundation (19JCJQJC62400)the 111 project of B12015。
文摘Anionic redox reaction(ARR) in layered manganese-based oxide cathodes has been considered as an effective strategy to improve the energy density of sodium-ion batteries.Mn-vacancy layered oxides deliver a high ARR-related capacity with small voltage hysteresis,however,they are limited by rapid capacity degradation and poor rate capability,which arise from inferior structure changes due to repeated redox of lattice oxygen.Herein,redox-inactive Ti^(4+)is introduced to substitute partial Mn^(4+)to form Na_(2) Ti_(0.5)Mn_(2.5)O_7(Na_(4/7)[□_(1/7)Ti_(1/7)Mn_(5/7)]O_(2),□ for Mn vacancies),which can effectively restrain unfavorable interlayer gliding of Na2 Mn307 at high charge voltages,as reflected by an ultralow-strain volume variation of 0.11%.There is no irreversible O_(2) evolution observed in Na_(2) Ti_(0.5)Mn_(2.5)O_7 upon charging,which stabilizes the lattice oxygen and ensures the overall structural stability.It exhibits increased capacity retention of 79.1% after 60 cycles in Na_(2) Ti_(0.5)Mn_(2.5)O_7(17.1% in Na_(2) Mn_(3) O_7) and good rate capability(92.1 mAh g^(-1) at 0.5 A g^(-1)).This investigation provides new insights into designing high-performance cathode materials with reversible ARR and structural stability for SIBs.
文摘Well - defined diblock copolymers Of styrene (St ) and ethylene oxide (EO )have been prepared by sequential living anionic polymerization of the twocomonomers in THF. Diphenyl methyl potassium has been used as initiator. Theblock copolymers were characterized in detail by methods Of size exclusion chromatography (SEC ) , 1H - Nab, FT - IR, dynamic mechanical analysis(Daal ) and WAXD.
基金supported by the National Natural Science Foundation of China (No.51709157)the Youth Interdisciplinary Science and Innovative Research Groups of Shandong University (No.2020QNQT014)。
文摘Pyrite is widely distributed in estuarine sediments as an inexpensive natural Fenton-like reagent,however,the mechanism on the hydroxyl radical(HO^(·))production by pyrite under estuarine environmental conditions is still poorly understood.The batch experiments were performed to investigate the effects of estuarine conditions including aging(in air,in water),seawater anions(Cl^(-),Br^(-)and HCO_(3)^(-))and light on the HO^(·)production by pyrite oxidation.The one-electron transfer dominated the process from O_(2) to HO^(·)induced by oxidation of pyrite.The Fe(oxyhydr)oxide coatings on the surface of pyrite aged in air and water consumed hydrogen peroxide while mediating the electron transfer,and the combined effect of the two resulted in a suppression of HO^(·)production in the early stage of aging and a promotion of HO^(·)production in the later stage of aging.Corrosion of the surface oxide layers by aggressive anions was the main reason for the inhibition of HO^(·)production by Cl^(-)and Br^(-),and the generation of Cl^(·)and Br^(·)may also play a role in the scavenging of HO^(·).HCO_(3)^(-)increased the average rate of HO^(·)production through surface-CO_(2) complexes formed by adsorption on the surface of pyrite.The significant enhancement of HO^(·)production under light was attributed to the formation of photoelectrons induced by photochemical reactions on pyrite and its surface oxide layers.These findings provide new insights into the environmental chemical behavior of pyrite in the estuary and enrich the understanding of natural remediation of estuarine environments.
基金the financial support from the Brazilian research funding agencies Coordination for the Improvement of Higher Education Personnel(CAPES)for the postdoctoral scholarshipresearch fellow National Council for Scientific and Technological Development(CNPq-Process 308044/20185)+1 种基金Minas Gerais State Agency for Research and Development(FAPEMIG)the financial support from the University of Queensland Research Stimulus Allocation 2(Fellowships)scheme for the year of 2021 for awarding a post-doctoral fellowship。
文摘Fluoride is an impurity in nickel sulfate production,which is required for electric vehicle batteries.Hydrous zirconium oxide(HZO)was evaluated for removing fl uoride from nickel sulfate solution.Maximum fluoride removal occurred at pH value 4 and optimal pH value is 4–5,considering Zr solubility.Fluoride availability decreases with pH due to hydrogen fluoride and zirconium fluoride aqueous species.Fluoride removal is initially rapid,with 50 wt.%removal in 7 min,followed by slow removal up to 68 wt.%after 72 h and follows second order rate kinetics.Fluoride removal was dominated by an ion exchange mechanism and resulting Zr–F bonds were observed using Fourier-transform infrared spectroscopy.The presence of nickel sulfate decreased loading capacity compared to a salt-free solution.HZO maintained adsorption capacity through five cycles of loading and regeneration.
