The degradation behavior of ethyl xanthate(EX) salt was the most widely used collector in sulfide mineral flotation and emission of flotation tailings with residual EX was harmful to environment. In this work, hydroge...The degradation behavior of ethyl xanthate(EX) salt was the most widely used collector in sulfide mineral flotation and emission of flotation tailings with residual EX was harmful to environment. In this work, hydrogen peroxide(H2O2) was investigated by UV-visible spectroscopy(UV/Vis) at different p H values from 3 to 12. For p H value from 5 to 12, EX was oxidized into ethyl per xanthate(EPX) by H2O2. Then EPX was further oxidized into thiosulfate(TS) salt rather than ethyl thiocarbonate(ETC) and this step was the reaction-limited step. Then depending on p H values, TS was degraded into sulphate and carbonate salts(p H>7) or elemental sulfur(p H<7). The kinetics data show that the degradation rate of EX increases with increasing the H2O2 concentration and is independent on the p H values. Without H2O2, EX is hydrolyzed to carbon disulfide fast at p H value <3.0, but the reaction of hydrolysis is undetectable at p H value >3.0 during test time.展开更多
The thermal decomposition temperature is one of the most important parameters to evaluate fire hazard of organic peroxide. A quantitative structure-property relationship model was proposed for estimating the thermal d...The thermal decomposition temperature is one of the most important parameters to evaluate fire hazard of organic peroxide. A quantitative structure-property relationship model was proposed for estimating the thermal decomposition temperatures of organic peroxides. The entire set of 38 organic peroxides was at random divided into a training set for model development and a prediction set for external model validation. The novel local molecular descriptors of AT1, AT2, AT3, AT4, AT5, AT6 and global molecular descriptor of ATC have been proposed in order to character organic peroxides’ molecular structures. An accurate quantitative structure-property relationship （QSPR） equation is developed for the thermal decomposition temperatures of organic peroxides. The statistical results showed that the QSPR model was obtained using the multiple linear regression （MLR） method with correlation coefficient （R）, standard deviation （S）, leave-one-out validation correlation coefficient （RCV） values of 0.9795, 6.5676 ℃ and 0.9328, respectively. The average absolute relative deviation （AARD） is only 3.86% for the experimental values. Model test by internal leave-one-out cross validation and external validation and molecular descriptor interpretation were discussed. Comparison with literature results demonstrated that novel local and global descriptors were useful molecular descriptors for predicting the thermal decomposition temperatures of organic peroxides.展开更多
Several mixtures,based on urea derivatives and some inorganic oxidants,including also alumina,were studied by means of ballistic mortar techniques with TNT as the reference standard.The detonation pressure(P),detonati...Several mixtures,based on urea derivatives and some inorganic oxidants,including also alumina,were studied by means of ballistic mortar techniques with TNT as the reference standard.The detonation pressure(P),detonation velocity(D),detonation energy(Q),and volume of gaseous product at standard temperature and pressure(STP),V,were calculated using EXPLO5V6.3 thermochemical code.The performance of the mixtures studied was discussed in relation to their thermal reactivity,determined by means of differential thermal analysis(DTA).It is shown that the presence of hydrogen peroxide in the form of its complex with urea(i.e.as UHP)has a positive influence on the explosive strength of the corresponding mixtures which is linked to the hydroxy-radical formation in the mixtures during their initiation reaction.These radicals might initiate(at least partially)powdered aluminum into oxidation in the CJ plane of the detonation wave.Mixtures containing UHP and magnesium are dangerous because of potential auto-ignition.展开更多
Changes in erythrocyte membrane ATPases and plasma lipid peroxides（LPO） were studiedperioperatively in 15 abdominal surgical patients under intravenous procaine-balanced anesthesia.The resultsrevealed that erythrocy...Changes in erythrocyte membrane ATPases and plasma lipid peroxides（LPO） were studiedperioperatively in 15 abdominal surgical patients under intravenous procaine-balanced anesthesia.The resultsrevealed that erythrocyte membrne Na<sup>+</sup>-K<sup>+</sup>ATPase,Mg<sup>2+</sup>ATPase and Ca<sup>2+</sup>-Mg<sup>2+</sup>ATPase activities werenot significantly changed at 60～90 min after incision as compared with 30 min before anesthesia,but weredecreased markedly at 10 rain and 24 hours after completion of operation（P【0.01）.Plasma LPO wereincreased significantly by 24 hours after surgery（P【0.01） following an initially marked but transientreduction.Plasma LPO changes were not correlated with erythrocyte membrane ATPase activities,r=-0.0396,-0.0097 and-0.4383 respeetively（P】0.05）.These correlations are suggested to be inducedby neuroendoerine responses after anesthesia and/or surgical trauma.展开更多
In situ highly sensitive and accurate tumor sensing is of great significance for early cancer diagnosis and treatment.Fluorescence sensing of tumor biomarkers has attracted considerable attention due to its advantages...In situ highly sensitive and accurate tumor sensing is of great significance for early cancer diagnosis and treatment.Fluorescence sensing of tumor biomarkers has attracted considerable attention due to its advantages of high sensitivity,operational simplicity,and capability for real-time in situ detection.Achieving high-quality tumor fluorescence imaging fundamentally depends on high-performance luminescent probes,and developing near-infrared-Ⅱ(NIR-Ⅱ)fluorescent probes with excellent tissue penetration depth and ultra‑high response sensitivity provides a highly promising solution path for this.Herein,we report a NIR-Ⅱ fluorescent probe,4,4'-{6,7-di(thiophen-2-yl)-[1,2,5]thiadiazolo[3,4-g]quinoxaline-4,9-diyl}bis{N,N-dimethyl-N-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzyl]benzenaminium}(TQT-Bpin),featuring aggregation-induced emission(AIE)characteristics.This probe can specifically respond to the hydrogen peroxide overexpressed in the tumor region,thereby in situ activating NIR-Ⅱ fluorescence emission.It exhibits exceptional sensitivity and specificity,enabling real-time and responsive sensing and imaging of hydrogen peroxide in tumor areas,with advantages including an ultra-large Stokes shift(320 nm),excellent selectivity(limit of detection down to 3.6μmol/L),and superior stability.Such an NIR-Ⅱ probe,which integrates deep tissue penetration,high sensitivity,and in situ responsiveness,provides a novel strategy for early diagnosis of tumors.展开更多
Electrochemiluminescence(ECL)of luminol has been studied on a screen-printed gold electrode for a simple and sensitive detection of arsenic ions(As(III)).Cyclic voltammetry(CV)was applied as the proposed technique to ...Electrochemiluminescence(ECL)of luminol has been studied on a screen-printed gold electrode for a simple and sensitive detection of arsenic ions(As(III)).Cyclic voltammetry(CV)was applied as the proposed technique to study luminol's electrochemical behavior and to evaluate the arsenic's effect in the ECL system,while hydrogen peroxide(H_(2)O_(2))served as a co-reactant to enhance luminol's light emission under alkaline conditions.To achieve optimal electrode performance,key parameters including pH,scan rate,and the concentrations of H_(2)O_(2)and luminol were carefully optimized.The presence of As(III)induced a quenching effect on the luminol/H_(2)O_(2)ECL system,leading to a linear decrease in ECL signal across the wide concentration range of 1 nmol·L^(-1)to 150μmol·L^(-1).The system demonstrated a low detection limit of 1.21 nmol·L^(-1)and exhibited excellent repeatability with a relative standard deviation of 2.27%,highlighting its sensitivity and reliability for As(III)detection.A key advantage of this study was the successful use of commercial bare electrodes,which were readily available and required no modifications,proving their effectiveness for ECL-based arsenic sensing.The optimized buffer solution pH of 10 played a critical role in enhancing arsenic detection selectivity,as it facilitated the optimal deprotonation of luminol and ensured arsenic remained in its dissolved state,whereas other potential metal ion interferences were more likely to form solid metal(hydro)oxides.Furthermore,the developed sensor was successfully applied for As(III)detection in a seawater matrix,demonstrating its potential as a robust and effective ECL-based arsenic sensor for environmental applications.展开更多
Unveiling the active site of an electrocatalyst is fundamental for the development of efficient electrode material.For the two-electron water oxidation to produce H_(2)O_(2),competitive reactions,including four-and on...Unveiling the active site of an electrocatalyst is fundamental for the development of efficient electrode material.For the two-electron water oxidation to produce H_(2)O_(2),competitive reactions,including four-and one-electron water oxidation and surface reconstruction derived from the high-oxidative environment co-existed,leading to great challenges to identify the real active sites on the electrode.In this work,Ti/TiO_(2)-based electrodes calcined under air,nitrogen,or urea atmospheres were selected as electrocatalysts for two-electron water oxidation.Electrochemical analyses were applied to evaluate the catalytic activity and selectivity.The morphological and current change on the electrode surface were determined by scanning electrochemical microscopy,while the chemical and valence evolutions with depth distributions were tested by XPS combined with cluster argon ion sputtering.The results demonstrated that Ti/TiO_(2) nanotube arrays served as the support,while the functional groups of carbonyl groups and pyrrolic nitrogen derived from the co-pyrolysis with urea were the active sites for the H_(2)O_(2) production.This finding provided a new horizon to design efficient catalysts for H_(2)O_(2) production.展开更多
A new type of thermal stabilizer, antimony pent（isooctyl thioglycollate）(Sb(SCH2COOC8H17)5), was synthesized by using antimony trioxide, isooctanol and thioglycolic acid in 2 steps. Firstly, antimony trioxide was ox...A new type of thermal stabilizer, antimony pent（isooctyl thioglycollate）(Sb(SCH2COOC8H17)5), was synthesized by using antimony trioxide, isooctanol and thioglycolic acid in 2 steps. Firstly, antimony trioxide was oxidized into colloidal antimony peroxide. Then antimony peroxide and isooctyl thioglycollate reacted stoichiometrically for 2 h with the yield of 87%. This compound was used as thermal stabilizer for polyvinyl chloride（PVC）. The results show that the thermal stability time is 52min at 200℃ by heat-ageing oven test when adding 2.5% thermal stabilizer to PVC resin. Compared with antimony tris（isooctyl thiolycollate）, the initial thermal stability of antimony pent（isooctyl thioglycollate） is better than that of antimony tris（isooctyl thioglycollate）, while the long-term thermal stability time is shorter than that of antimony tris（isooctyl thioglycollate）. Meanwhile, the synergism of antimony pent（isooctyl thioglycollate） with calcium stearate was studied, indicating that when the mass ratio of antimony pent（isooctyl thioglycollate） to calcium stearate is （2∶1,） the thermal stability time of PVC is 58min.展开更多
Aim To investigate the protective effects of icariin（ICA） on oxidative injury of human umbilical vascu- lar endothelial cells （HUVEC） caused by H202 and analysis action machenisms of ICA. Methods HUVEC were cultur...Aim To investigate the protective effects of icariin（ICA） on oxidative injury of human umbilical vascu- lar endothelial cells （HUVEC） caused by H202 and analysis action machenisms of ICA. Methods HUVEC were cultured in DMEM medium with 10% fetal bovine serum and 1% antibiotic mixture comprising penicillin and strep- tomycin, at 37℃; with 5% CO2 in vitro. The model of oxidative injury was established by H202 （ 750 μmol · L^-1 ）. The cells were divided into six groups： control group, H202 group, H202 ＋ ICA（ 10-8, 10-7, 10-6 tool · L^-1 ） group and H202 ＋ DMSO （solvent） ; HUVEC were treated with different concentration ICA according to grou- os before 12h H202 treatment and cultured for 12, 24 and 36h respectively, the cell vitality （OD value） and the level of ROS was measured by MTT and ELISA. The apoptosis and death of HUVEC were detected using Annexin V-FITC/PI kit. Real Time RT-PCR was used to detect Bcl-2 and Bax mRNA expression in the HUVEC. Results Compared with control group, cell vitality significantly declined （P 〈 0.01 ） , the level of ROS and the number of apoptotic HUVEC notably increased （P 〈 0. 01 ） in H202 group. Compared with H202 group, ICA treatment could increase HUVEC vitality and reduce level of ROS （P 〈 0.01 or P 〈 0. 05） with manners of time-dependence and dose-dependence,ICA treatment could decrease the apoptosis and death rate of HUVEC （P 〈 0.01 ）. ICA treat- ment could also down-regulate the expression of Bax mRNA （ P 〈 0.05 ） and up-regulate the expression of Bcl-2 （ P 〈 0.05）. Conclusion The ICA can alleviate the oxidative injury of HUVEC induced by H202 treatment. The ac- tion mechanisms of ICA may, at least partly, be related to inhibit HUVEC apoptosis caused by H202 treatment through up-regulation of expression of Bcl-2 and down-regulation of expression of Bax mRNA.展开更多
Oxidative stress is one of the main causes of neurodegenerative diseases such as Alzheimer disease(AD).Our previous studies have shown that artemisinin,a anti-malaria Chinese medicine,with neuroprotective effect,howev...Oxidative stress is one of the main causes of neurodegenerative diseases such as Alzheimer disease(AD).Our previous studies have shown that artemisinin,a anti-malaria Chinese medicine,with neuroprotective effect,however,the antioxidative effect of artemisinin and its potential mechanism remain to be elucidated.In the present study,the protective effect and the underlying mechanism of artemisinin against injury of hydrogen peroxide(H_2O_2) in SH-SY5Y and hippocampal neurons were studied.Our results show that artemisinin protected SH-SY5Y and hippocampal neuronal cells from H_2O_2-induced cell death at clinically relevant concentrations in a concentration-dependent manner.Further studies showed that artemisinin significantly reduced cell death caused by H_2O_2 by restoring nuclear morphology,abnormal changes in intracellular ROS,activation of caspase 3,lactate dehydrogenase release and mitochondrial membrane potential.Hoechst staining and flow cytometry showed that artemisinin significantly reduced the apoptosis of SH-SY5Y cells exposed to H_2O_2.Western blotting analysis showed that artemisinin stimulated the phosphorylation and activation of AMP-activated protein kinase(AMPK) in SH-SY5Y cells in a time and concentration-dependent manner,whereas the application of AMPK inhibitor Compound C or decrease in expression of AMPKα with shRNA specific for AMPKα blocked the protective effect of artemisinin.Similar results were obtained in primary cultured hippocampal neurons.Taken together,these results indicate that artemisinin can protect neuronal cells from oxidative damage,at least in part through the activation of AMPK.Because artemisinin is relatively inexpensive and has few side effects,our findings support the role of artemisinin as a potential therapeutic agent for neurodegenerative diseases.展开更多
A rapid and sensitive fluorometric method for the enzymatic detection of ethanol using CdSe/ZnS quantum dots （QDs） is proposed. The photoluminescence of QDs is sensitive to H202. This finding leads to a novel approa...A rapid and sensitive fluorometric method for the enzymatic detection of ethanol using CdSe/ZnS quantum dots （QDs） is proposed. The photoluminescence of QDs is sensitive to H202. This finding leads to a novel approach for the determination of ethanol using alcohol oxidase （AOx） which, on oxidation of ethanol, produces H202. The method has higher sensitivity, wider analytical range （0.1-8 mmol/L）, and a lower detection limit （0.05 mmol/L）. The relationship between quenching of the photoluminescence of the QDs and the concentration of ethanol is linear.展开更多
OBJECTIVE N2L is a novel lipoic acid-niacin dimer regulating lipid metabolism with multifunction,including antioxidant effect.We investigated the protective effect of N2L and the underlying mechanisms under the ferrop...OBJECTIVE N2L is a novel lipoic acid-niacin dimer regulating lipid metabolism with multifunction,including antioxidant effect.We investigated the protective effect of N2L and the underlying mechanisms under the ferroptosis inducer RAS-selective lethality 3(RSL3)treat⁃ment in HT22 cells.METHODS HT22 cells were pretreated with N2L and then were treated with RSL3 to establish a ferroptosis cell model.MTT assay was used to detect the cell survival rate.Free radical probe(dihydroethidium,DHE)and ferrous probe FerroOrange were used to detect the contents of free radicals and ferrous ions in cells.The ultrastructure of mitochondria of treat⁃ed cells was observed by transmission electron microscope.The expression of ferroptosis-relat⁃ed proteins acyl-CoA synthetase long-chain family member 4(ACSL4),glutathione peroxidase 4(GPX4),cyclooxygenase-2(COX-2),ferritin Heavy Chain 1(FTH1),nuclear factor E2-related factor 2/heme oxygenase-1,and phosphoryla⁃tion levels of the c-Jun N-terminal kinase(JNK)/extracellular regulated protein kinases(ERK)pathway were detected by Western blotting.RE⁃SULTS RSL3 decreased the cell viability and induced excessive accumulation of(reactive oxy⁃gen species)ROS in HT22 cells.N2L pretreat⁃ment effectively protected HT22 cells against lipid peroxidation.What′s more,N2L recovered GPX4 protein expression and blocked the increase of COX-2 and ACSL4 expressions.Moreover,N2L also significantly prevented FTH1 from downregulation and maintained iron homeo⁃stasis.Finally,N2L pretreatment could decrease JNK/ERK activation induced by RSL3.CON⁃CLUSION N2L is an excellent ferroptosis inhibi⁃tor,and its anti-ferroptosis mechanism may be related to the reduction of lipid peroxidation and the regulation of iron homeostasis.展开更多
Water culture experiment was conducted to study the effects of selenium(Se) on glutathione peroxidase(GSH-Px) activity,reduced glutathione(GSH) concentration and the accumulation of malonaldehyde(MDA),the product of l...Water culture experiment was conducted to study the effects of selenium(Se) on glutathione peroxidase(GSH-Px) activity,reduced glutathione(GSH) concentration and the accumulation of malonaldehyde(MDA),the product of lipid peroxidation in rice seedling,as well as the effect of se on oxidizing ability of roots under ferrous stress.Results showed that appropriate amount of se significantly increased GSH-Px activity in rice leaves,F=5.5 *,enhanced the amount of GSH and oxidizing ability of roots and reduced the concentration of MDA,F=4.9 *.Compared with Se0+Fe treatment,Se treatments increased the dry matter weight of rice seedling from 10.06% to 10.43%,F=4.09 *.展开更多
Experiments were conducted to study the effects of selenium (Se) on glutathione peroxidase(GSH-Px) activity and the accumulation of malonaldehyde(MDA),the product of lipid peroxidation in soybean seedling, as well as ...Experiments were conducted to study the effects of selenium (Se) on glutathione peroxidase(GSH-Px) activity and the accumulation of malonaldehyde(MDA),the product of lipid peroxidation in soybean seedling, as well as the effect of Se on cell ultra structure of soybean leaf and nascent root under salt stress. Results showed that appropriate amount of Se addition increased GSH-Px activity in soybean leaves from 0. 810 to 1. 421μmol·g-1 fresh weight·min-1 F = 9.12, and reduced the concentration of MDA from 20.17 to 16.16 μmol·g-1 fresh weight, F = 5.44. Under salt stress,no obvious damage on chloplast membrane was observed in Se treated seedlings,and the structures of chloplast and mitochondrion were integrate,whereas in control (no Se addition),the cell membrane was destroyed seriously,chloplast degraded and mitochondrion disappeared. Compared with control,Se addition increased the dry matter weight of seedling by 2.92% to 21.86%, F =5.97.展开更多
Reports the effects of selenium on lipid peroxidation of soybean under continuous cropping stress.Results of pot culture and plot experiment showed that appropriate amount of Se addition increased the activity of glut...Reports the effects of selenium on lipid peroxidation of soybean under continuous cropping stress.Results of pot culture and plot experiment showed that appropriate amount of Se addition increased the activity of glutathione peroxidase (GSH-Px) significantly,and cleared away the excessive free radicals existing in soybean plant under continuous cropping stress,decreased the concentration of malonaldehyde(MDA),which is the end product of lipid peroxidation,maintained the perfection of chloroplast and mitochondrion structure,enhanced the resistance of continuous cropped soybean,and therefore increased the dry weight of seedlong and yield.展开更多
Four varieties of winter wheat with different return green rates were used to analyze the plasma membrane stability and the factors that affect winter wheat in the frigid region during winter. The removal of reactive ...Four varieties of winter wheat with different return green rates were used to analyze the plasma membrane stability and the factors that affect winter wheat in the frigid region during winter. The removal of reactive oxygen species, the degree of plasma membrane impairment, water composition and content, and the changes in cell viability in the crowns, which contain the growing point, were studied during the period from cold acclimation to the deep freezing. The results showed that electrical conductivity which reflects the degree of plasma membrane damaged under low temperature was significantly correlated with the free water and the total water content. The malondialdehyde （MDA） content, which reflects the degree of membrane peroxidation, was very significantly correlated with superoxide dismutase （SOD）, peroxidase, and ascorbic acid. During the deep freezing period, the SOD activity and glutathione （GSH） content of the winter wheat varieties were relative to their cold resistance. During this period, the MDA stability, SOD, GSH, and the total water and the free water content might be used to identify the cold resistance of winter wheat varieties.展开更多
基金Project(2013AA064102)supported by the National High Technology Research and Development Program of ChinaProject(B14034)supported by the Program of Introducing Talents of Discipline to Universities,ChinaProject supported by the 2011 Collaborative Innovation Center for Clean and Efficient utilization of Strategic Metal Mineral Resources,China
文摘The degradation behavior of ethyl xanthate(EX) salt was the most widely used collector in sulfide mineral flotation and emission of flotation tailings with residual EX was harmful to environment. In this work, hydrogen peroxide(H2O2) was investigated by UV-visible spectroscopy(UV/Vis) at different p H values from 3 to 12. For p H value from 5 to 12, EX was oxidized into ethyl per xanthate(EPX) by H2O2. Then EPX was further oxidized into thiosulfate(TS) salt rather than ethyl thiocarbonate(ETC) and this step was the reaction-limited step. Then depending on p H values, TS was degraded into sulphate and carbonate salts(p H>7) or elemental sulfur(p H<7). The kinetics data show that the degradation rate of EX increases with increasing the H2O2 concentration and is independent on the p H values. Without H2O2, EX is hydrolyzed to carbon disulfide fast at p H value <3.0, but the reaction of hydrolysis is undetectable at p H value >3.0 during test time.
基金Project(2015SK20823) supported by Science and Technology Project of Hunan Province,ChinaProject(15A001) supported by Scientific Research Fund of Hunan Provincial Education Department,China+2 种基金Project(2017CL06) supported by Hunan Provincial Key Laboratory of Materials Protection for Electric Power and Transportation,ChinaProject(k1403029-11) supported by Science and Technology Project of Changsha City,ChinaProject(CX2015B372) supported by the Hunan Provincial Innovation Foundation for Postgraduate,China
文摘The thermal decomposition temperature is one of the most important parameters to evaluate fire hazard of organic peroxide. A quantitative structure-property relationship model was proposed for estimating the thermal decomposition temperatures of organic peroxides. The entire set of 38 organic peroxides was at random divided into a training set for model development and a prediction set for external model validation. The novel local molecular descriptors of AT1, AT2, AT3, AT4, AT5, AT6 and global molecular descriptor of ATC have been proposed in order to character organic peroxides’ molecular structures. An accurate quantitative structure-property relationship （QSPR） equation is developed for the thermal decomposition temperatures of organic peroxides. The statistical results showed that the QSPR model was obtained using the multiple linear regression （MLR） method with correlation coefficient （R）, standard deviation （S）, leave-one-out validation correlation coefficient （RCV） values of 0.9795, 6.5676 ℃ and 0.9328, respectively. The average absolute relative deviation （AARD） is only 3.86% for the experimental values. Model test by internal leave-one-out cross validation and external validation and molecular descriptor interpretation were discussed. Comparison with literature results demonstrated that novel local and global descriptors were useful molecular descriptors for predicting the thermal decomposition temperatures of organic peroxides.
基金supported by means of the financial resources of Students Grant Projects No.SGSFCHT_2016002 of the Faculty of Chemical Technology at the University of Pardubice
文摘Several mixtures,based on urea derivatives and some inorganic oxidants,including also alumina,were studied by means of ballistic mortar techniques with TNT as the reference standard.The detonation pressure(P),detonation velocity(D),detonation energy(Q),and volume of gaseous product at standard temperature and pressure(STP),V,were calculated using EXPLO5V6.3 thermochemical code.The performance of the mixtures studied was discussed in relation to their thermal reactivity,determined by means of differential thermal analysis(DTA).It is shown that the presence of hydrogen peroxide in the form of its complex with urea(i.e.as UHP)has a positive influence on the explosive strength of the corresponding mixtures which is linked to the hydroxy-radical formation in the mixtures during their initiation reaction.These radicals might initiate(at least partially)powdered aluminum into oxidation in the CJ plane of the detonation wave.Mixtures containing UHP and magnesium are dangerous because of potential auto-ignition.
文摘Changes in erythrocyte membrane ATPases and plasma lipid peroxides（LPO） were studiedperioperatively in 15 abdominal surgical patients under intravenous procaine-balanced anesthesia.The resultsrevealed that erythrocyte membrne Na<sup>+</sup>-K<sup>+</sup>ATPase,Mg<sup>2+</sup>ATPase and Ca<sup>2+</sup>-Mg<sup>2+</sup>ATPase activities werenot significantly changed at 60～90 min after incision as compared with 30 min before anesthesia,but weredecreased markedly at 10 rain and 24 hours after completion of operation（P【0.01）.Plasma LPO wereincreased significantly by 24 hours after surgery（P【0.01） following an initially marked but transientreduction.Plasma LPO changes were not correlated with erythrocyte membrane ATPase activities,r=-0.0396,-0.0097 and-0.4383 respeetively（P】0.05）.These correlations are suggested to be inducedby neuroendoerine responses after anesthesia and/or surgical trauma.
文摘In situ highly sensitive and accurate tumor sensing is of great significance for early cancer diagnosis and treatment.Fluorescence sensing of tumor biomarkers has attracted considerable attention due to its advantages of high sensitivity,operational simplicity,and capability for real-time in situ detection.Achieving high-quality tumor fluorescence imaging fundamentally depends on high-performance luminescent probes,and developing near-infrared-Ⅱ(NIR-Ⅱ)fluorescent probes with excellent tissue penetration depth and ultra‑high response sensitivity provides a highly promising solution path for this.Herein,we report a NIR-Ⅱ fluorescent probe,4,4'-{6,7-di(thiophen-2-yl)-[1,2,5]thiadiazolo[3,4-g]quinoxaline-4,9-diyl}bis{N,N-dimethyl-N-[4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzyl]benzenaminium}(TQT-Bpin),featuring aggregation-induced emission(AIE)characteristics.This probe can specifically respond to the hydrogen peroxide overexpressed in the tumor region,thereby in situ activating NIR-Ⅱ fluorescence emission.It exhibits exceptional sensitivity and specificity,enabling real-time and responsive sensing and imaging of hydrogen peroxide in tumor areas,with advantages including an ultra-large Stokes shift(320 nm),excellent selectivity(limit of detection down to 3.6μmol/L),and superior stability.Such an NIR-Ⅱ probe,which integrates deep tissue penetration,high sensitivity,and in situ responsiveness,provides a novel strategy for early diagnosis of tumors.
基金Directorate of Research and Development,Universitas Indonesia under Bilateral Strategic Alliance(UI-UTM BISA)Research Collaboration Agreement(Matching Fund)2023(Grant No.NKB-1181/UN2.RST/HKP.05.00/2023)。
文摘Electrochemiluminescence(ECL)of luminol has been studied on a screen-printed gold electrode for a simple and sensitive detection of arsenic ions(As(III)).Cyclic voltammetry(CV)was applied as the proposed technique to study luminol's electrochemical behavior and to evaluate the arsenic's effect in the ECL system,while hydrogen peroxide(H_(2)O_(2))served as a co-reactant to enhance luminol's light emission under alkaline conditions.To achieve optimal electrode performance,key parameters including pH,scan rate,and the concentrations of H_(2)O_(2)and luminol were carefully optimized.The presence of As(III)induced a quenching effect on the luminol/H_(2)O_(2)ECL system,leading to a linear decrease in ECL signal across the wide concentration range of 1 nmol·L^(-1)to 150μmol·L^(-1).The system demonstrated a low detection limit of 1.21 nmol·L^(-1)and exhibited excellent repeatability with a relative standard deviation of 2.27%,highlighting its sensitivity and reliability for As(III)detection.A key advantage of this study was the successful use of commercial bare electrodes,which were readily available and required no modifications,proving their effectiveness for ECL-based arsenic sensing.The optimized buffer solution pH of 10 played a critical role in enhancing arsenic detection selectivity,as it facilitated the optimal deprotonation of luminol and ensured arsenic remained in its dissolved state,whereas other potential metal ion interferences were more likely to form solid metal(hydro)oxides.Furthermore,the developed sensor was successfully applied for As(III)detection in a seawater matrix,demonstrating its potential as a robust and effective ECL-based arsenic sensor for environmental applications.
基金Project(2021JJ30792) supported by the Natural Science Foundation of Hunan Province,ChinaProject(52170031) supported by the National Natural Science Foundation of ChinaProject supported by the Fundamental Research Funds for the Central Universities,China。
文摘Unveiling the active site of an electrocatalyst is fundamental for the development of efficient electrode material.For the two-electron water oxidation to produce H_(2)O_(2),competitive reactions,including four-and one-electron water oxidation and surface reconstruction derived from the high-oxidative environment co-existed,leading to great challenges to identify the real active sites on the electrode.In this work,Ti/TiO_(2)-based electrodes calcined under air,nitrogen,or urea atmospheres were selected as electrocatalysts for two-electron water oxidation.Electrochemical analyses were applied to evaluate the catalytic activity and selectivity.The morphological and current change on the electrode surface were determined by scanning electrochemical microscopy,while the chemical and valence evolutions with depth distributions were tested by XPS combined with cluster argon ion sputtering.The results demonstrated that Ti/TiO_(2) nanotube arrays served as the support,while the functional groups of carbonyl groups and pyrrolic nitrogen derived from the co-pyrolysis with urea were the active sites for the H_(2)O_(2) production.This finding provided a new horizon to design efficient catalysts for H_(2)O_(2) production.
基金Project supported by the Postdoctoral Foundation of Central South University
文摘A new type of thermal stabilizer, antimony pent（isooctyl thioglycollate）(Sb(SCH2COOC8H17)5), was synthesized by using antimony trioxide, isooctanol and thioglycolic acid in 2 steps. Firstly, antimony trioxide was oxidized into colloidal antimony peroxide. Then antimony peroxide and isooctyl thioglycollate reacted stoichiometrically for 2 h with the yield of 87%. This compound was used as thermal stabilizer for polyvinyl chloride（PVC）. The results show that the thermal stability time is 52min at 200℃ by heat-ageing oven test when adding 2.5% thermal stabilizer to PVC resin. Compared with antimony tris（isooctyl thiolycollate）, the initial thermal stability of antimony pent（isooctyl thioglycollate） is better than that of antimony tris（isooctyl thioglycollate）, while the long-term thermal stability time is shorter than that of antimony tris（isooctyl thioglycollate）. Meanwhile, the synergism of antimony pent（isooctyl thioglycollate） with calcium stearate was studied, indicating that when the mass ratio of antimony pent（isooctyl thioglycollate） to calcium stearate is （2∶1,） the thermal stability time of PVC is 58min.
文摘Aim To investigate the protective effects of icariin（ICA） on oxidative injury of human umbilical vascu- lar endothelial cells （HUVEC） caused by H202 and analysis action machenisms of ICA. Methods HUVEC were cultured in DMEM medium with 10% fetal bovine serum and 1% antibiotic mixture comprising penicillin and strep- tomycin, at 37℃; with 5% CO2 in vitro. The model of oxidative injury was established by H202 （ 750 μmol · L^-1 ）. The cells were divided into six groups： control group, H202 group, H202 ＋ ICA（ 10-8, 10-7, 10-6 tool · L^-1 ） group and H202 ＋ DMSO （solvent） ; HUVEC were treated with different concentration ICA according to grou- os before 12h H202 treatment and cultured for 12, 24 and 36h respectively, the cell vitality （OD value） and the level of ROS was measured by MTT and ELISA. The apoptosis and death of HUVEC were detected using Annexin V-FITC/PI kit. Real Time RT-PCR was used to detect Bcl-2 and Bax mRNA expression in the HUVEC. Results Compared with control group, cell vitality significantly declined （P 〈 0.01 ） , the level of ROS and the number of apoptotic HUVEC notably increased （P 〈 0. 01 ） in H202 group. Compared with H202 group, ICA treatment could increase HUVEC vitality and reduce level of ROS （P 〈 0.01 or P 〈 0. 05） with manners of time-dependence and dose-dependence,ICA treatment could decrease the apoptosis and death rate of HUVEC （P 〈 0.01 ）. ICA treat- ment could also down-regulate the expression of Bax mRNA （ P 〈 0.05 ） and up-regulate the expression of Bcl-2 （ P 〈 0.05）. Conclusion The ICA can alleviate the oxidative injury of HUVEC induced by H202 treatment. The ac- tion mechanisms of ICA may, at least partly, be related to inhibit HUVEC apoptosis caused by H202 treatment through up-regulation of expression of Bcl-2 and down-regulation of expression of Bax mRNA.
基金National Natural Science Foundation of China(31771128)the University of Macao (MYRG2016-00052-FHS+2 种基金MYRG2018-00134-FHS)Science and Technology Development Fund (FDCT)of Macao (FDCT 021/2015/A1016/2016/A1).
文摘Oxidative stress is one of the main causes of neurodegenerative diseases such as Alzheimer disease(AD).Our previous studies have shown that artemisinin,a anti-malaria Chinese medicine,with neuroprotective effect,however,the antioxidative effect of artemisinin and its potential mechanism remain to be elucidated.In the present study,the protective effect and the underlying mechanism of artemisinin against injury of hydrogen peroxide(H_2O_2) in SH-SY5Y and hippocampal neurons were studied.Our results show that artemisinin protected SH-SY5Y and hippocampal neuronal cells from H_2O_2-induced cell death at clinically relevant concentrations in a concentration-dependent manner.Further studies showed that artemisinin significantly reduced cell death caused by H_2O_2 by restoring nuclear morphology,abnormal changes in intracellular ROS,activation of caspase 3,lactate dehydrogenase release and mitochondrial membrane potential.Hoechst staining and flow cytometry showed that artemisinin significantly reduced the apoptosis of SH-SY5Y cells exposed to H_2O_2.Western blotting analysis showed that artemisinin stimulated the phosphorylation and activation of AMP-activated protein kinase(AMPK) in SH-SY5Y cells in a time and concentration-dependent manner,whereas the application of AMPK inhibitor Compound C or decrease in expression of AMPKα with shRNA specific for AMPKα blocked the protective effect of artemisinin.Similar results were obtained in primary cultured hippocampal neurons.Taken together,these results indicate that artemisinin can protect neuronal cells from oxidative damage,at least in part through the activation of AMPK.Because artemisinin is relatively inexpensive and has few side effects,our findings support the role of artemisinin as a potential therapeutic agent for neurodegenerative diseases.
基金Project(21005067)supported by the National Natural Science Foundation of ChinaProject(11JJ4015)supported by Natural Science Foundation of Hunan Province,China
文摘A rapid and sensitive fluorometric method for the enzymatic detection of ethanol using CdSe/ZnS quantum dots （QDs） is proposed. The photoluminescence of QDs is sensitive to H202. This finding leads to a novel approach for the determination of ethanol using alcohol oxidase （AOx） which, on oxidation of ethanol, produces H202. The method has higher sensitivity, wider analytical range （0.1-8 mmol/L）, and a lower detection limit （0.05 mmol/L）. The relationship between quenching of the photoluminescence of the QDs and the concentration of ethanol is linear.
文摘OBJECTIVE N2L is a novel lipoic acid-niacin dimer regulating lipid metabolism with multifunction,including antioxidant effect.We investigated the protective effect of N2L and the underlying mechanisms under the ferroptosis inducer RAS-selective lethality 3(RSL3)treat⁃ment in HT22 cells.METHODS HT22 cells were pretreated with N2L and then were treated with RSL3 to establish a ferroptosis cell model.MTT assay was used to detect the cell survival rate.Free radical probe(dihydroethidium,DHE)and ferrous probe FerroOrange were used to detect the contents of free radicals and ferrous ions in cells.The ultrastructure of mitochondria of treat⁃ed cells was observed by transmission electron microscope.The expression of ferroptosis-relat⁃ed proteins acyl-CoA synthetase long-chain family member 4(ACSL4),glutathione peroxidase 4(GPX4),cyclooxygenase-2(COX-2),ferritin Heavy Chain 1(FTH1),nuclear factor E2-related factor 2/heme oxygenase-1,and phosphoryla⁃tion levels of the c-Jun N-terminal kinase(JNK)/extracellular regulated protein kinases(ERK)pathway were detected by Western blotting.RE⁃SULTS RSL3 decreased the cell viability and induced excessive accumulation of(reactive oxy⁃gen species)ROS in HT22 cells.N2L pretreat⁃ment effectively protected HT22 cells against lipid peroxidation.What′s more,N2L recovered GPX4 protein expression and blocked the increase of COX-2 and ACSL4 expressions.Moreover,N2L also significantly prevented FTH1 from downregulation and maintained iron homeo⁃stasis.Finally,N2L pretreatment could decrease JNK/ERK activation induced by RSL3.CON⁃CLUSION N2L is an excellent ferroptosis inhibi⁃tor,and its anti-ferroptosis mechanism may be related to the reduction of lipid peroxidation and the regulation of iron homeostasis.
文摘Water culture experiment was conducted to study the effects of selenium(Se) on glutathione peroxidase(GSH-Px) activity,reduced glutathione(GSH) concentration and the accumulation of malonaldehyde(MDA),the product of lipid peroxidation in rice seedling,as well as the effect of se on oxidizing ability of roots under ferrous stress.Results showed that appropriate amount of se significantly increased GSH-Px activity in rice leaves,F=5.5 *,enhanced the amount of GSH and oxidizing ability of roots and reduced the concentration of MDA,F=4.9 *.Compared with Se0+Fe treatment,Se treatments increased the dry matter weight of rice seedling from 10.06% to 10.43%,F=4.09 *.
文摘Experiments were conducted to study the effects of selenium (Se) on glutathione peroxidase(GSH-Px) activity and the accumulation of malonaldehyde(MDA),the product of lipid peroxidation in soybean seedling, as well as the effect of Se on cell ultra structure of soybean leaf and nascent root under salt stress. Results showed that appropriate amount of Se addition increased GSH-Px activity in soybean leaves from 0. 810 to 1. 421μmol·g-1 fresh weight·min-1 F = 9.12, and reduced the concentration of MDA from 20.17 to 16.16 μmol·g-1 fresh weight, F = 5.44. Under salt stress,no obvious damage on chloplast membrane was observed in Se treated seedlings,and the structures of chloplast and mitochondrion were integrate,whereas in control (no Se addition),the cell membrane was destroyed seriously,chloplast degraded and mitochondrion disappeared. Compared with control,Se addition increased the dry matter weight of seedling by 2.92% to 21.86%, F =5.97.
基金National Nature Science Foundation projectgrant No:39870 4 70 Natural Scieuce Foundation of Heilongjiang Province
文摘Reports the effects of selenium on lipid peroxidation of soybean under continuous cropping stress.Results of pot culture and plot experiment showed that appropriate amount of Se addition increased the activity of glutathione peroxidase (GSH-Px) significantly,and cleared away the excessive free radicals existing in soybean plant under continuous cropping stress,decreased the concentration of malonaldehyde(MDA),which is the end product of lipid peroxidation,maintained the perfection of chloroplast and mitochondrion structure,enhanced the resistance of continuous cropped soybean,and therefore increased the dry weight of seedlong and yield.
基金Supported by the Postdoctoral Science Foundation of Heilongjiang Province(2010RCB17)Doctoral Research Startup Foundation of Northeast Agricultural University(LBH-Z10266)+2 种基金New Rural Project of Heilongjiang Provincial Department of EducationProject of Education Department in Heilongjiang Province(12521035)Postgraduate Innovation Project of Education Department in Heilongjiang Province (YJSCX2012-036HLJ)
文摘Four varieties of winter wheat with different return green rates were used to analyze the plasma membrane stability and the factors that affect winter wheat in the frigid region during winter. The removal of reactive oxygen species, the degree of plasma membrane impairment, water composition and content, and the changes in cell viability in the crowns, which contain the growing point, were studied during the period from cold acclimation to the deep freezing. The results showed that electrical conductivity which reflects the degree of plasma membrane damaged under low temperature was significantly correlated with the free water and the total water content. The malondialdehyde （MDA） content, which reflects the degree of membrane peroxidation, was very significantly correlated with superoxide dismutase （SOD）, peroxidase, and ascorbic acid. During the deep freezing period, the SOD activity and glutathione （GSH） content of the winter wheat varieties were relative to their cold resistance. During this period, the MDA stability, SOD, GSH, and the total water and the free water content might be used to identify the cold resistance of winter wheat varieties.
