After treated with low concentration of La^3 ＋ , the rate of producing active oxygen free radical, the relative permeability of cell membrane, the contents of bivalent iron ion in wheat seedling leaves under water st...After treated with low concentration of La^3 ＋ , the rate of producing active oxygen free radical, the relative permeability of cell membrane, the contents of bivalent iron ion in wheat seedling leaves under water stress were determined. The results show that in wheat seedling leaves, feasible concentrations of La^3 ＋ decreases the accumulation of active oxygen free radical, inhibits the increase of the relative permeability of cell membrane, reduces the content of peroxidation product MDA of membrane lipid, and prevents the plant cell producing more bivalent iron ion which can catalyzed the reaction of Haber-weiss and Fenton to produce more superoxide anion. In addition, purified plasma membrane was isolated by aqueous two-phase partitioning from wheat seedling leaves. The reduction rate of Fe（CN）6^3- by purified plasma membrane in La^3＋ -treated wheat seedling leaves is different from those in the absence of La^3＋ under water stress. The changing trend of the redox activity to La^3＋ is similar to that of the content of Fe^2＋ . The results reveal that extraneous La^3＋ can alleviate the damages of cell membrane caused by water stress via promoting the activity of redox system and the ability of eliminating ROS in wheat seedling leaves.展开更多
The effects of lanthanum on some redox system(PMRS) properties of the plasma membrane(PM) vesicles from Casuarina equisetifolia seedlings under artificial acid rain(pH 4.5)stress were studied. The results show tha...The effects of lanthanum on some redox system(PMRS) properties of the plasma membrane(PM) vesicles from Casuarina equisetifolia seedlings under artificial acid rain(pH 4.5)stress were studied. The results show that there are NADH oxidase and EDTA Fe 3+ reductase, and nitrate reductase in the seedling PM, and they have different responses to soaking seeds for 8 h in a series of LaCl 3 solution. The NADH oxidase activities and the Nitrate reductase activities can be stimulated when La 3+ concentrations is in the range of 50～200 mg·L -1 , but their activities are inhibited or fluctuate by the higher La 3+ concentrations. The EDTA Fe 3+ reductase activities can be stimulated by La 3+ concentrations in the range of 50～400 mg·L -1 . The research also revealed that La 3+ reduces the relative permeability of membranes and have the function in protecting membranes under acid rain stress by the way of inhibiting the leakage of electrolyte.展开更多
The unicellular halotolerant alga Dunaliella salina had the ability to oxidize NADH and reduce Fe(CN)63-. The redox reactions were to some extent stimulated by slight hyperosmotic shock (2.0 mol/L → 2.6 mol/L NaCl), ...The unicellular halotolerant alga Dunaliella salina had the ability to oxidize NADH and reduce Fe(CN)63-. The redox reactions were to some extent stimulated by slight hyperosmotic shock (2.0 mol/L → 2.6 mol/L NaCl), butmarkably inhibited by abrupt hyperosmotic shock (2.0mol/L → 3.5 mol/L NaCl) and hypoosmotic shock (2.0mol/L → 1.0 mol/L NaCl; 2.0 mol/L→0.67 mol/L NaCl).With the adaptation of algal cells to osmotic shock by accumulating or degrading intracellular glycerol, the plasmalemma redox activities were also restored. The O2 uptake stimulated by NADH could be promoted by FA and SHAM. Hypoosmotic shock increases the basal respiration rate of alga cells, but weakened the stimulating effects of NADH, FA and SHAM on O2 uptake. On the other hand, hyperosmotic shock reduced the basal respiration rate, but relatively enhanced the above effects of NADH, FA and SHAM. H+ extrusion of alga cells was inhibited by NADH and stimulated by Fe(CN)63- Vanadate and DES could inhibit H+ efflux, but had little effect in the presence of NADH and Fe(CN)63-. Both hyperand hypoosmotic shock stimulated H+ extrusion. This effect could be totally inhibited by vanadate and DES, but almost unaffected by 8-hydroxyquinoline. It was suggested that H+-ATPase probably played a more important role in H+ extrusion and osmoregulation under the conditions of osmotic shock.展开更多
The dependence of the molecular weights on the concentration of reactants in the polymerization of acrylonitrile initiated by vanadium (V)-thiourea redox system has been investigated. It was found that the molecular w...The dependence of the molecular weights on the concentration of reactants in the polymerization of acrylonitrile initiated by vanadium (V)-thiourea redox system has been investigated. It was found that the molecular weights of the polymer change nonlinearly with increasing concentrations of nitric acid and thiourea. Probably, the composition of the complexes exert a great influence on the chain initiation and termination. The reaction of 'complextermination' gives rise to the decrease of the molecular weights markedly while the concentrations of thiourea and vanadium (V)in the range from one to three molar ratios.展开更多
The initiation mechanism of acrylamide (AAM)polymerization using ceric ion/acetylacetone system as an initiator has been studied. The redox polymerization was revealed by the low value of overall activation energy of ...The initiation mechanism of acrylamide (AAM)polymerization using ceric ion/acetylacetone system as an initiator has been studied. The redox polymerization was revealed by the low value of overall activation energy of AAm polymerization. The structure of free radicals formed from above-mentioned initiation sytem were detected by radical trapping and ESR spectra techniques and the end groups of polymers obtained were determined by FT-IR spectra analysis method. Based on these results the initiation mechanism is proposed.展开更多
The kinetics of polymerization of acrylonitrile (AN) initiated by quinquevalent vanadium (V^(5+))-thiourea (TU) redox system has been investigated in aqueous nitric acid in the temperature range from 30 to 50℃. The p...The kinetics of polymerization of acrylonitrile (AN) initiated by quinquevalent vanadium (V^(5+))-thiourea (TU) redox system has been investigated in aqueous nitric acid in the temperature range from 30 to 50℃. The polymerization rate (R_p) can be expressed as follows: In the copolymerization of acryionitrile with methyl acrylate (MA), the reactivity ratios were found to be 1.0 and 1.1, respectively. The experimental observations suggest that the initiating species is probably a complex consisting of a central ion of Lewis acid-VO_2^+ and the ligands of Lewis bases-acrylonitrile, thiourea, and nitrate anions, while the initiating system in lower concentration, the polymerization of acrylonitrile does not occur if the thiourea is acidified prior to its reaction with quinquevalent vanadium. This indicates that the primary radicals (or the monomeric radicals in the present article) are produced by associated thiourea rather than isothlourea.展开更多
The polymerization of acrylonitrile (AN) in aqueous nitric acid initiated by metavanadate-containing anion exchange resin (PV)-thiourea (TU) redox system at 20—40℃. has been investigated. The overall rate of polymer...The polymerization of acrylonitrile (AN) in aqueous nitric acid initiated by metavanadate-containing anion exchange resin (PV)-thiourea (TU) redox system at 20—40℃. has been investigated. The overall rate of polymerization (R_p) is given byR_p=1.92×10~4e^(-6.860/RT) [AN]^(1.2) [PV]^(0.44) [TU]^(1.0)[HNO_3]^(1.0)The kinetic parameters differed from those of V^(5+)-TU system indicated that the generation of the primary radicals is mainly a difffusion-controlled reaction. The effect of macromolecular field arisen from the polymer matrix exerts a great influence on the polymerization process.展开更多
The in-situ FTIR spectroscopic results show that a hemi-ketal in- termediate may be produced in the electroreduction of benzoquinone or electro- oxidation of benzohydroquinone,which provides a valuable insight into th...The in-situ FTIR spectroscopic results show that a hemi-ketal in- termediate may be produced in the electroreduction of benzoquinone or electro- oxidation of benzohydroquinone,which provides a valuable insight into the me- chanism of the redox process.展开更多
A complex example of electrolytic redox system involving 47 species, 3 electron-active elements and five (3 am-phiprotic + 2 aprotic) co-solvents, is presented. Mixed solvates of the species thus formed are admitted i...A complex example of electrolytic redox system involving 47 species, 3 electron-active elements and five (3 am-phiprotic + 2 aprotic) co-solvents, is presented. Mixed solvates of the species thus formed are admitted in the system considered. It is proved that the Generalized Electron Balance (GEB) in its simplest form obtained according to the Approach II to GEB is identical with the one obtained for aqueous media and binary-solvent system, and is equivalent to the Approach I to GEB.展开更多
The Generalized Electron Balance (GEB), together with charge balance and concentration balances, completes the set of equations needed for resolution of electrolytic redox systems. The general formulae for GEB were ob...The Generalized Electron Balance (GEB), together with charge balance and concentration balances, completes the set of equations needed for resolution of electrolytic redox systems. The general formulae for GEB were obtained according to Approach II to GEB, i.e., on the basis of the equation 2?f(O) ? f(H) obtained from elemental balances: f(H) for H, and f(O) for O. Equivalency of the Approach II and the Approach I to GEB was proved for an aqueous solution and a binary-solvent system. On this basis, a compact form of GEB was derived.展开更多
Background: Weaning is known to result in barrier dysfunction and villus atrophy in the immediate post-weaning phase, and the magnitude of these responses is hypothesized to correlate with changes in the glutathione(G...Background: Weaning is known to result in barrier dysfunction and villus atrophy in the immediate post-weaning phase, and the magnitude of these responses is hypothesized to correlate with changes in the glutathione(GSH)redox system. Therefore, these parameters were simultaneously measured throughout the weaning phase, in piglets differing in birth weight category and weaning age, as these pre-weaning factors are important determinants for the weaning transition. Low birth weight(LBW) and normal birth weight(NBW) littermates were assigned to one of three weaning treatments;i.e. weaning at 3 weeks of age(3 w), weaning at 4 weeks of age(4 w) and removal from the sow at 3 d of age and fed a milk replacer until weaning at 3 weeks of age(3 d3 w). For each of these treatments, six LBW and six NBW piglets were euthanized at 0, 2, 5, 12 or 28 d post-weaning piglets, adding up 180 piglets.Results: Weaning increased the glutathione peroxidase activity on d 5 post-weaning in plasma, and duodenal and jejunal mucosa. Small intestinal glutathione-S-transferase activity gradually increased until d 12 post-weaning, and this was combined with a progressive rise of mucosal GSH up till d 12 post-weaning. Oxidation of the GSH redox status(GSH/GSSG Eh) was only observed in the small intestinal mucosa of 3 d3 w weaned piglets at d 5 postweaning. These piglets also demonstrated increased fluorescein isothiocyanate dextran(FD4) and horseradish peroxidase fluxes in the duodenum and distal jejunum during the experiment, and specifically demonstrated increased FD4 fluxes at d 2 to d 5 post-weaning. On the other hand, profound villus atrophy was observed during the weaning transition for all weaning treatments. Finally, LBW and NBW piglets did not demonstrate notable differences in GSH redox status, small intestinal barrier function and histo-morphology throughout the experiment.Conclusion: Although moderate changes in the GSH redox system were observed upon weaning, the GSH redox status remained at a steady state level in 3 w and 4 w weaned piglets and was therefore not associated with weaning induced villus atrophy. Conversely, 3 d3 w weaned piglets demonstrated GSH redox imbalance in the small intestinal mucosa, and this co-occurred with a temporal malfunction of their intestinal barrier function.展开更多
The plasma membrane was isolated and purified by using the method of aqueous two phase partitioning from rice (Oryza sativa) seedling roots. The effect of LaCl 3 on the activity of redox system of plasma membran...The plasma membrane was isolated and purified by using the method of aqueous two phase partitioning from rice (Oryza sativa) seedling roots. The effect of LaCl 3 on the activity of redox system of plasma membrane has been studied. The reduction rate of Fe(CN) 3- 6 and the oxidation rate of NADH in plasma membrane are stimulated below the concentration of 40 μmol·L -1 , but depressed in pace with the increasing of LaCl 3 over the concentration of 40 μmol·L -1 . The possible effect of LaCl 3 on the uptake of Fe element by rice seedling was also discussed.展开更多
The formalism realised according to the Generalised Approach to Electrolytic Systems (GATES) is presented and applied to typical redox systems known from the laboratory practice. In any redox system, the Generalized E...The formalism realised according to the Generalised Approach to Electrolytic Systems (GATES) is presented and applied to typical redox systems known from the laboratory practice. In any redox system, the Generalized Electron Balance (GEB), perceived as the law of the matter conservation, is derivable from linear combination 2·f(O) – f(H) of elemental balances: f(O) for oxygen and f(H) for hydrogen. It is an equation linearly independent from other (charge and concentration) balances referred to an electrolytic redox system (aqueous media) of any degree of complexity, and named as the primary form of GEB and then denoted as pr-GEB. A compact equation for GEB is obtained from linear combination of 2·f(O) – f(H) with other (charge and concentration) balances. For a non-redox electrolytic system, of any degree of complexity, the balance 2·f(O) – f(H) is not an independent equation. In the derivation of GEB, all known components (species) of the system tested, taken in their real (i.e., hydrated) form, are involved in the balances, and none simplifying assumptions are needed. The redox systems are simulated with use of an iterative computer program.展开更多
The sodium persulfate(Na_(2)S_(2)O_(8))-urea system has been proven to be an excellent scrubbing solution for the wet removal of NO.Commonly,seawater is used as a wet carrier in marine applications.To further explore ...The sodium persulfate(Na_(2)S_(2)O_(8))-urea system has been proven to be an excellent scrubbing solution for the wet removal of NO.Commonly,seawater is used as a wet carrier in marine applications.To further explore the feasibility of marine denitrification using Na_(2)S_(2)O_(8)-urea system,this study proposed the Na_(2)S_(2)O_(8)-urea-seawater composite redox system for NO removal from the marine exhaust gas.The effects of seawater carrier,reaction temperature,Na_(2)S_(2)O_(8)concentration,urea concentration,pH value,and NO concentration on NO removal were investigated.Additionally,the NO_(3)−concentration in the solution was measured.Results showed that the lowest normalized NO concentration was 0.099,with the corresponding mass of NO absorbed per unit volume of solution reaching 0.108 g·L^(−1).The addition of seawater carrier and incremental reaction temperature,Na_(2)S_(2)O_(8),and urea concentration promoted the NO removal performance.When the pH value increased within the range of 4-7,the NO removal performance decreased.The NO removal performance increased as the pH value further increased to 8,but decreased again when the pH value increased to 11.An increase in NO concentration was detrimental to NO removal.The Cl^(−),HCO_(3)^(−),and CO_(3)^(2−)in seawater could augment the total concentration of active free radicals to improve denitrification performance.展开更多
Metal halide perovskites(MHPs)with striking electrical and optical properties have appeared at the forefront of semiconductor materials for photocatalytic redox reactions but still suffer from some intrinsic drawbacks...Metal halide perovskites(MHPs)with striking electrical and optical properties have appeared at the forefront of semiconductor materials for photocatalytic redox reactions but still suffer from some intrinsic drawbacks such as inferior stability,severe charge-carrier recombination,and limited active sites.Heterojunctions have recently been widely constructed to improve light absorption,passivate surface for enhanced stability,and promote charge-carrier dynamics of MHPs.However,little attention has been paid to the review of MHPs-based heterojunctions for photocatalytic redox reactions.Here,recent advances of MHPs-based heterojunctions for photocatalytic redox reactions are highlighted.The structure,synthesis,and photophysical properties of MHPs-based heterojunctions are first introduced,including basic principles,categories(such as Schottky junction,type-I,type-II,Z-scheme,and S-scheme junction),and synthesis strategies.MHPs-based heterojunctions for photocatalytic redox reactions are then reviewed in four categories:H2evolution,CO_(2)reduction,pollutant degradation,and organic synthesis.The challenges and prospects in solar-light-driven redox reactions with MHPs-based heterojunctions in the future are finally discussed.展开更多
In this paper, it is proved that linear combination 2·f(O)?- f(H) of elemental balances: f(O) for O and f(H) for H is linearly independent on charge and elemental/core balances for all redox systems of any degree...In this paper, it is proved that linear combination 2·f(O)?- f(H) of elemental balances: f(O) for O and f(H) for H is linearly independent on charge and elemental/core balances for all redox systems of any degree of complexity;it is the primary form of the Generalized Electron Balance (GEB), , considered as the Approach II to GEB. The Approach II is equivalent to the Approach I based on the principle of common pool of electrons. Both Approaches are illustrated on an example of titration of acidified (H2SO4) solution of H2C2O4 with KMnO4. It is also stated, on an example of titration of the same solution with NaOH, that 2·f(O)?- f(H) is a linear combination of charge and elemental/core balances, i.e. it is not an independent balance when related to the non-redox system. These properties of 2·f(O)?- f(H) can be extended on redox and non-redox systems, of any degree of complexity, i.e. the linear independency/dependency of 2·f(O)?- f(H) on other balances related to a system in question is a criterion distinguishing redox and non-redox systems. The GEB completes the set of (charge and concentration) balances and a set of expressions for independent equilibrium constants needed for modeling the related redox system.展开更多
Peroxisome-proliferator-activated receptors(PPARs) comprise three subtypes(PPARα,δ and γ) to form a nuclear receptor superfamily.PPARs act as key transcriptional regulators of lipid metabolism,mitochondrial biogene...Peroxisome-proliferator-activated receptors(PPARs) comprise three subtypes(PPARα,δ and γ) to form a nuclear receptor superfamily.PPARs act as key transcriptional regulators of lipid metabolism,mitochondrial biogenesis,and anti-oxidant defense.While their roles in regulating lipid metabolism have been well established,the role of PPARs in regulating redox activity remains incompletely understood.Since redox activity is an integral part of oxidative metabolism,it is not surprising that changes in PPAR signaling in a specific cell or tissue will lead to alteration of redox state.The effects of PPAR signaling are directly related to PPAR expression,protein activities and PPAR interactions with their coregulators.The three subtypes of PPARs regulate cellular lipid and energy metabolism in most tissues in the body with overlapping and preferential effects on different metabolic steps depending on a specific tissue.Adding to the complexity,specific ligands of each PPAR subtype may also display different potencies and specificities of their role on regulating the redox pathways.Moreover,the intensity and extension of redoxregulation by each PPAR subtype are varied depending on different tissues and cell types.Both beneficial and adverse effects of PPAR ligands against cardiovascular disorders have been extensively studied by many groups.The purpose of the review is to summarize the effects of each PPAR on regulating redox and the underlying mechanisms,as well as to discuss the implications in the cardiovascular system.展开更多
Cancer is a big challenge that has plagued the human beings for ages and one of the most effective treatments is chemotherapy. However, the low tumor-targeting ability limits the wide clinical application of chemother...Cancer is a big challenge that has plagued the human beings for ages and one of the most effective treatments is chemotherapy. However, the low tumor-targeting ability limits the wide clinical application of chemotherapy. The microenvironment plays a critical role in many aspects of tumor genesis. It generates the tumor vasculature and it is highly implicated in the progression to metastasis. To maintain a suitable environment for tumor progression, there are special microenvironment in tumor cell, such as low pH, high level of glutathione(GSH) and reactive oxygen species(ROS), and more special enzymes, which is different to normal cell. Microenvironment-targeted therapy strategy could create new opportunities for therapeutic targeting. Compared to other targeting strategies, microenvironment-targeted therapy strategy will control the drug release into tumor cells more accurately. Redox responsive drug delivery systems(DDSs) are developed based on the high level of GSH in tumor cells. However, there are also GSH in normal cell though its level is lower. In order to control the release of drugs more accurately and reduce side effects, other drug release stimuli have been introduced to redox responsive DDSs. Under the synergistic reaction of two stimuli, redox dual-stimuli responsive DDSs will control the release of drugs more accurately and quickly and even increase the accumulation. This review summarizes strategies of redox dual-stimuli responsive DDSs such as pH, light, enzyme, ROS, and magnetic guide to delivery chemotherapeutic agents more accurately, aiming at providing new ideas for further promoting the drug release,enhancing tumor-targeting and improving anticancer effects. To better illustrate the redox dual-stimuli responsive DDS, preparations of carriers are also briefly described in the review.展开更多
Large-scale electrical energy storage with high energy density and round-trip efficiency is important to the resilience of power grids and the effective use of intermittent renewable energy such as solar and wind.Lith...Large-scale electrical energy storage with high energy density and round-trip efficiency is important to the resilience of power grids and the effective use of intermittent renewable energy such as solar and wind.Lithiumoxygen battery,due to its high energy density,is believed to be one of the most promising energy storage systems for the future.However,large overpotentials,poor cycling stability,and degradation of electrolytes and cathodes have been hindering the development of lithium-oxygen batteries.Numerous heterogeneous oxygen electrocatalysts have been investigated to lower the overpotentials and enhance the cycling stability of lithium-oxygen batteries.Unfortunately,the prevailing issues of electrode passivation and clogging remain.Over the past few years,redox mediators were explored as homogenous catalysts to address the issues,while only limited success has been achieved for these soluble catalysts.In conjunction with a flowing electrolyte system,a new redox flow lithium-oxygen battery(RFLOB)has been devised to tackle the aforementioned issues.The working mechanism and schematic processes will be elaborated in this review.In addition,the performance gap of RFLOB with respect to practical requirements will be analysed.With the above,we anticipate RFLOB would be a credible solution for the implementation of lithium-oxygen battery chemistry for the next generation energy storage.展开更多
基金Project supported bythe National Natural Science Foundation of China (30270744) and 863 Program(2002AA241121)
文摘After treated with low concentration of La^3 ＋ , the rate of producing active oxygen free radical, the relative permeability of cell membrane, the contents of bivalent iron ion in wheat seedling leaves under water stress were determined. The results show that in wheat seedling leaves, feasible concentrations of La^3 ＋ decreases the accumulation of active oxygen free radical, inhibits the increase of the relative permeability of cell membrane, reduces the content of peroxidation product MDA of membrane lipid, and prevents the plant cell producing more bivalent iron ion which can catalyzed the reaction of Haber-weiss and Fenton to produce more superoxide anion. In addition, purified plasma membrane was isolated by aqueous two-phase partitioning from wheat seedling leaves. The reduction rate of Fe（CN）6^3- by purified plasma membrane in La^3＋ -treated wheat seedling leaves is different from those in the absence of La^3＋ under water stress. The changing trend of the redox activity to La^3＋ is similar to that of the content of Fe^2＋ . The results reveal that extraneous La^3＋ can alleviate the damages of cell membrane caused by water stress via promoting the activity of redox system and the ability of eliminating ROS in wheat seedling leaves.
文摘The effects of lanthanum on some redox system(PMRS) properties of the plasma membrane(PM) vesicles from Casuarina equisetifolia seedlings under artificial acid rain(pH 4.5)stress were studied. The results show that there are NADH oxidase and EDTA Fe 3+ reductase, and nitrate reductase in the seedling PM, and they have different responses to soaking seeds for 8 h in a series of LaCl 3 solution. The NADH oxidase activities and the Nitrate reductase activities can be stimulated when La 3+ concentrations is in the range of 50～200 mg·L -1 , but their activities are inhibited or fluctuate by the higher La 3+ concentrations. The EDTA Fe 3+ reductase activities can be stimulated by La 3+ concentrations in the range of 50～400 mg·L -1 . The research also revealed that La 3+ reduces the relative permeability of membranes and have the function in protecting membranes under acid rain stress by the way of inhibiting the leakage of electrolyte.
文摘The unicellular halotolerant alga Dunaliella salina had the ability to oxidize NADH and reduce Fe(CN)63-. The redox reactions were to some extent stimulated by slight hyperosmotic shock (2.0 mol/L → 2.6 mol/L NaCl), butmarkably inhibited by abrupt hyperosmotic shock (2.0mol/L → 3.5 mol/L NaCl) and hypoosmotic shock (2.0mol/L → 1.0 mol/L NaCl; 2.0 mol/L→0.67 mol/L NaCl).With the adaptation of algal cells to osmotic shock by accumulating or degrading intracellular glycerol, the plasmalemma redox activities were also restored. The O2 uptake stimulated by NADH could be promoted by FA and SHAM. Hypoosmotic shock increases the basal respiration rate of alga cells, but weakened the stimulating effects of NADH, FA and SHAM on O2 uptake. On the other hand, hyperosmotic shock reduced the basal respiration rate, but relatively enhanced the above effects of NADH, FA and SHAM. H+ extrusion of alga cells was inhibited by NADH and stimulated by Fe(CN)63- Vanadate and DES could inhibit H+ efflux, but had little effect in the presence of NADH and Fe(CN)63-. Both hyperand hypoosmotic shock stimulated H+ extrusion. This effect could be totally inhibited by vanadate and DES, but almost unaffected by 8-hydroxyquinoline. It was suggested that H+-ATPase probably played a more important role in H+ extrusion and osmoregulation under the conditions of osmotic shock.
文摘The dependence of the molecular weights on the concentration of reactants in the polymerization of acrylonitrile initiated by vanadium (V)-thiourea redox system has been investigated. It was found that the molecular weights of the polymer change nonlinearly with increasing concentrations of nitric acid and thiourea. Probably, the composition of the complexes exert a great influence on the chain initiation and termination. The reaction of 'complextermination' gives rise to the decrease of the molecular weights markedly while the concentrations of thiourea and vanadium (V)in the range from one to three molar ratios.
基金The project was supported by the National Natural Science Foundation of China
文摘The initiation mechanism of acrylamide (AAM)polymerization using ceric ion/acetylacetone system as an initiator has been studied. The redox polymerization was revealed by the low value of overall activation energy of AAm polymerization. The structure of free radicals formed from above-mentioned initiation sytem were detected by radical trapping and ESR spectra techniques and the end groups of polymers obtained were determined by FT-IR spectra analysis method. Based on these results the initiation mechanism is proposed.
文摘The kinetics of polymerization of acrylonitrile (AN) initiated by quinquevalent vanadium (V^(5+))-thiourea (TU) redox system has been investigated in aqueous nitric acid in the temperature range from 30 to 50℃. The polymerization rate (R_p) can be expressed as follows: In the copolymerization of acryionitrile with methyl acrylate (MA), the reactivity ratios were found to be 1.0 and 1.1, respectively. The experimental observations suggest that the initiating species is probably a complex consisting of a central ion of Lewis acid-VO_2^+ and the ligands of Lewis bases-acrylonitrile, thiourea, and nitrate anions, while the initiating system in lower concentration, the polymerization of acrylonitrile does not occur if the thiourea is acidified prior to its reaction with quinquevalent vanadium. This indicates that the primary radicals (or the monomeric radicals in the present article) are produced by associated thiourea rather than isothlourea.
文摘The polymerization of acrylonitrile (AN) in aqueous nitric acid initiated by metavanadate-containing anion exchange resin (PV)-thiourea (TU) redox system at 20—40℃. has been investigated. The overall rate of polymerization (R_p) is given byR_p=1.92×10~4e^(-6.860/RT) [AN]^(1.2) [PV]^(0.44) [TU]^(1.0)[HNO_3]^(1.0)The kinetic parameters differed from those of V^(5+)-TU system indicated that the generation of the primary radicals is mainly a difffusion-controlled reaction. The effect of macromolecular field arisen from the polymer matrix exerts a great influence on the polymerization process.
文摘The in-situ FTIR spectroscopic results show that a hemi-ketal in- termediate may be produced in the electroreduction of benzoquinone or electro- oxidation of benzohydroquinone,which provides a valuable insight into the me- chanism of the redox process.
文摘A complex example of electrolytic redox system involving 47 species, 3 electron-active elements and five (3 am-phiprotic + 2 aprotic) co-solvents, is presented. Mixed solvates of the species thus formed are admitted in the system considered. It is proved that the Generalized Electron Balance (GEB) in its simplest form obtained according to the Approach II to GEB is identical with the one obtained for aqueous media and binary-solvent system, and is equivalent to the Approach I to GEB.
文摘The Generalized Electron Balance (GEB), together with charge balance and concentration balances, completes the set of equations needed for resolution of electrolytic redox systems. The general formulae for GEB were obtained according to Approach II to GEB, i.e., on the basis of the equation 2?f(O) ? f(H) obtained from elemental balances: f(H) for H, and f(O) for O. Equivalency of the Approach II and the Approach I to GEB was proved for an aqueous solution and a binary-solvent system. On this basis, a compact form of GEB was derived.
基金supported by a grant from the government agency for Innovation by Science and Technology (IWT-LO 100856)。
文摘Background: Weaning is known to result in barrier dysfunction and villus atrophy in the immediate post-weaning phase, and the magnitude of these responses is hypothesized to correlate with changes in the glutathione(GSH)redox system. Therefore, these parameters were simultaneously measured throughout the weaning phase, in piglets differing in birth weight category and weaning age, as these pre-weaning factors are important determinants for the weaning transition. Low birth weight(LBW) and normal birth weight(NBW) littermates were assigned to one of three weaning treatments;i.e. weaning at 3 weeks of age(3 w), weaning at 4 weeks of age(4 w) and removal from the sow at 3 d of age and fed a milk replacer until weaning at 3 weeks of age(3 d3 w). For each of these treatments, six LBW and six NBW piglets were euthanized at 0, 2, 5, 12 or 28 d post-weaning piglets, adding up 180 piglets.Results: Weaning increased the glutathione peroxidase activity on d 5 post-weaning in plasma, and duodenal and jejunal mucosa. Small intestinal glutathione-S-transferase activity gradually increased until d 12 post-weaning, and this was combined with a progressive rise of mucosal GSH up till d 12 post-weaning. Oxidation of the GSH redox status(GSH/GSSG Eh) was only observed in the small intestinal mucosa of 3 d3 w weaned piglets at d 5 postweaning. These piglets also demonstrated increased fluorescein isothiocyanate dextran(FD4) and horseradish peroxidase fluxes in the duodenum and distal jejunum during the experiment, and specifically demonstrated increased FD4 fluxes at d 2 to d 5 post-weaning. On the other hand, profound villus atrophy was observed during the weaning transition for all weaning treatments. Finally, LBW and NBW piglets did not demonstrate notable differences in GSH redox status, small intestinal barrier function and histo-morphology throughout the experiment.Conclusion: Although moderate changes in the GSH redox system were observed upon weaning, the GSH redox status remained at a steady state level in 3 w and 4 w weaned piglets and was therefore not associated with weaning induced villus atrophy. Conversely, 3 d3 w weaned piglets demonstrated GSH redox imbalance in the small intestinal mucosa, and this co-occurred with a temporal malfunction of their intestinal barrier function.
文摘The plasma membrane was isolated and purified by using the method of aqueous two phase partitioning from rice (Oryza sativa) seedling roots. The effect of LaCl 3 on the activity of redox system of plasma membrane has been studied. The reduction rate of Fe(CN) 3- 6 and the oxidation rate of NADH in plasma membrane are stimulated below the concentration of 40 μmol·L -1 , but depressed in pace with the increasing of LaCl 3 over the concentration of 40 μmol·L -1 . The possible effect of LaCl 3 on the uptake of Fe element by rice seedling was also discussed.
文摘The formalism realised according to the Generalised Approach to Electrolytic Systems (GATES) is presented and applied to typical redox systems known from the laboratory practice. In any redox system, the Generalized Electron Balance (GEB), perceived as the law of the matter conservation, is derivable from linear combination 2·f(O) – f(H) of elemental balances: f(O) for oxygen and f(H) for hydrogen. It is an equation linearly independent from other (charge and concentration) balances referred to an electrolytic redox system (aqueous media) of any degree of complexity, and named as the primary form of GEB and then denoted as pr-GEB. A compact equation for GEB is obtained from linear combination of 2·f(O) – f(H) with other (charge and concentration) balances. For a non-redox electrolytic system, of any degree of complexity, the balance 2·f(O) – f(H) is not an independent equation. In the derivation of GEB, all known components (species) of the system tested, taken in their real (i.e., hydrated) form, are involved in the balances, and none simplifying assumptions are needed. The redox systems are simulated with use of an iterative computer program.
基金supported by the National Natural Science Foundation of China(Grant No.U1906232)Major Scientific and Technological Innovation Project of Shandong Province(China)(No.2020CXGC011402)Shandong Excellent Young Scientists Fund Program(Overseas)(No.2023HWYQ-021).
文摘The sodium persulfate(Na_(2)S_(2)O_(8))-urea system has been proven to be an excellent scrubbing solution for the wet removal of NO.Commonly,seawater is used as a wet carrier in marine applications.To further explore the feasibility of marine denitrification using Na_(2)S_(2)O_(8)-urea system,this study proposed the Na_(2)S_(2)O_(8)-urea-seawater composite redox system for NO removal from the marine exhaust gas.The effects of seawater carrier,reaction temperature,Na_(2)S_(2)O_(8)concentration,urea concentration,pH value,and NO concentration on NO removal were investigated.Additionally,the NO_(3)−concentration in the solution was measured.Results showed that the lowest normalized NO concentration was 0.099,with the corresponding mass of NO absorbed per unit volume of solution reaching 0.108 g·L^(−1).The addition of seawater carrier and incremental reaction temperature,Na_(2)S_(2)O_(8),and urea concentration promoted the NO removal performance.When the pH value increased within the range of 4-7,the NO removal performance decreased.The NO removal performance increased as the pH value further increased to 8,but decreased again when the pH value increased to 11.An increase in NO concentration was detrimental to NO removal.The Cl^(−),HCO_(3)^(−),and CO_(3)^(2−)in seawater could augment the total concentration of active free radicals to improve denitrification performance.
基金financially supported by National Natural Science Foundation of China(No.22302155)the Fundamental Research Funds of the Center Universities(No.D5000240188)the research program of ZJUT(YJY-ZS-20240001)。
文摘Metal halide perovskites(MHPs)with striking electrical and optical properties have appeared at the forefront of semiconductor materials for photocatalytic redox reactions but still suffer from some intrinsic drawbacks such as inferior stability,severe charge-carrier recombination,and limited active sites.Heterojunctions have recently been widely constructed to improve light absorption,passivate surface for enhanced stability,and promote charge-carrier dynamics of MHPs.However,little attention has been paid to the review of MHPs-based heterojunctions for photocatalytic redox reactions.Here,recent advances of MHPs-based heterojunctions for photocatalytic redox reactions are highlighted.The structure,synthesis,and photophysical properties of MHPs-based heterojunctions are first introduced,including basic principles,categories(such as Schottky junction,type-I,type-II,Z-scheme,and S-scheme junction),and synthesis strategies.MHPs-based heterojunctions for photocatalytic redox reactions are then reviewed in four categories:H2evolution,CO_(2)reduction,pollutant degradation,and organic synthesis.The challenges and prospects in solar-light-driven redox reactions with MHPs-based heterojunctions in the future are finally discussed.
文摘In this paper, it is proved that linear combination 2·f(O)?- f(H) of elemental balances: f(O) for O and f(H) for H is linearly independent on charge and elemental/core balances for all redox systems of any degree of complexity;it is the primary form of the Generalized Electron Balance (GEB), , considered as the Approach II to GEB. The Approach II is equivalent to the Approach I based on the principle of common pool of electrons. Both Approaches are illustrated on an example of titration of acidified (H2SO4) solution of H2C2O4 with KMnO4. It is also stated, on an example of titration of the same solution with NaOH, that 2·f(O)?- f(H) is a linear combination of charge and elemental/core balances, i.e. it is not an independent balance when related to the non-redox system. These properties of 2·f(O)?- f(H) can be extended on redox and non-redox systems, of any degree of complexity, i.e. the linear independency/dependency of 2·f(O)?- f(H) on other balances related to a system in question is a criterion distinguishing redox and non-redox systems. The GEB completes the set of (charge and concentration) balances and a set of expressions for independent equilibrium constants needed for modeling the related redox system.
基金Supported by Grants from National Institutes of Health,1R01 HL085499 to Yang Q, NO.1R01 HL084456,and NO.T32 HL007457 to Kim Tthe ADA Basic Science Award,#7-12-BS-208,to Yang Q
文摘Peroxisome-proliferator-activated receptors(PPARs) comprise three subtypes(PPARα,δ and γ) to form a nuclear receptor superfamily.PPARs act as key transcriptional regulators of lipid metabolism,mitochondrial biogenesis,and anti-oxidant defense.While their roles in regulating lipid metabolism have been well established,the role of PPARs in regulating redox activity remains incompletely understood.Since redox activity is an integral part of oxidative metabolism,it is not surprising that changes in PPAR signaling in a specific cell or tissue will lead to alteration of redox state.The effects of PPAR signaling are directly related to PPAR expression,protein activities and PPAR interactions with their coregulators.The three subtypes of PPARs regulate cellular lipid and energy metabolism in most tissues in the body with overlapping and preferential effects on different metabolic steps depending on a specific tissue.Adding to the complexity,specific ligands of each PPAR subtype may also display different potencies and specificities of their role on regulating the redox pathways.Moreover,the intensity and extension of redoxregulation by each PPAR subtype are varied depending on different tissues and cell types.Both beneficial and adverse effects of PPAR ligands against cardiovascular disorders have been extensively studied by many groups.The purpose of the review is to summarize the effects of each PPAR on regulating redox and the underlying mechanisms,as well as to discuss the implications in the cardiovascular system.
基金National Natural Science Foundation of China (81202480,81302723)Natural Science Foundation of Liaoning Province (2015020749)。
文摘Cancer is a big challenge that has plagued the human beings for ages and one of the most effective treatments is chemotherapy. However, the low tumor-targeting ability limits the wide clinical application of chemotherapy. The microenvironment plays a critical role in many aspects of tumor genesis. It generates the tumor vasculature and it is highly implicated in the progression to metastasis. To maintain a suitable environment for tumor progression, there are special microenvironment in tumor cell, such as low pH, high level of glutathione(GSH) and reactive oxygen species(ROS), and more special enzymes, which is different to normal cell. Microenvironment-targeted therapy strategy could create new opportunities for therapeutic targeting. Compared to other targeting strategies, microenvironment-targeted therapy strategy will control the drug release into tumor cells more accurately. Redox responsive drug delivery systems(DDSs) are developed based on the high level of GSH in tumor cells. However, there are also GSH in normal cell though its level is lower. In order to control the release of drugs more accurately and reduce side effects, other drug release stimuli have been introduced to redox responsive DDSs. Under the synergistic reaction of two stimuli, redox dual-stimuli responsive DDSs will control the release of drugs more accurately and quickly and even increase the accumulation. This review summarizes strategies of redox dual-stimuli responsive DDSs such as pH, light, enzyme, ROS, and magnetic guide to delivery chemotherapeutic agents more accurately, aiming at providing new ideas for further promoting the drug release,enhancing tumor-targeting and improving anticancer effects. To better illustrate the redox dual-stimuli responsive DDS, preparations of carriers are also briefly described in the review.
基金supported by the National Research Foundation, Prime Minister’s Office, Singapore, under its Competitive Research Program (CRP Awards No.NRF-CRP10-2012-06)
文摘Large-scale electrical energy storage with high energy density and round-trip efficiency is important to the resilience of power grids and the effective use of intermittent renewable energy such as solar and wind.Lithiumoxygen battery,due to its high energy density,is believed to be one of the most promising energy storage systems for the future.However,large overpotentials,poor cycling stability,and degradation of electrolytes and cathodes have been hindering the development of lithium-oxygen batteries.Numerous heterogeneous oxygen electrocatalysts have been investigated to lower the overpotentials and enhance the cycling stability of lithium-oxygen batteries.Unfortunately,the prevailing issues of electrode passivation and clogging remain.Over the past few years,redox mediators were explored as homogenous catalysts to address the issues,while only limited success has been achieved for these soluble catalysts.In conjunction with a flowing electrolyte system,a new redox flow lithium-oxygen battery(RFLOB)has been devised to tackle the aforementioned issues.The working mechanism and schematic processes will be elaborated in this review.In addition,the performance gap of RFLOB with respect to practical requirements will be analysed.With the above,we anticipate RFLOB would be a credible solution for the implementation of lithium-oxygen battery chemistry for the next generation energy storage.
