Methylene blue sensitized singlet oxygen oxidation of dl-α-tocopherol in dodecylsulfate (SDS) or cetyl trimethyl ammonium brondde (CTAB) ndcelles led to the formation, besidesα-tocopherol quinone and its epoxide, of...Methylene blue sensitized singlet oxygen oxidation of dl-α-tocopherol in dodecylsulfate (SDS) or cetyl trimethyl ammonium brondde (CTAB) ndcelles led to the formation, besidesα-tocopherol quinone and its epoxide, of a hitherto unknown spiro compound 6-hydroxy-2,6,8,9-tetramethyl-2-phytyl- 1-oxaspiro [4, 5] dec -8 - en - 7, 10-dione.展开更多
For catalytic materials,the characteristics of one-dimension and hollowness are the promotion factors for their full presentation of catalytic activity,and through a template-as sis ted method,both above superiorities...For catalytic materials,the characteristics of one-dimension and hollowness are the promotion factors for their full presentation of catalytic activity,and through a template-as sis ted method,both above superiorities can be fused simultaneously.Here,we proposed a novel strategy inspired by Pearson's principle with Cu_(2)O wires as templates,and prepared FeOOH hollow tubes,which covered by FeOOH scales.When applied as oxygen evolution reaction(OER)catalyst,the FeOOH scaly hollow tubes(FeOOH SHTs)showed outstanding catalytic activity with a low overpotential of 245 mV to drive a current density of10 mA·cm^(-2),excellent kinetics manifesting as a low Tafel slope of 46.9 mV·dec^(-1),and robust stability.This work provides a new synthesis strategy for an ideal OER catalyst,FeOOH,with high inherent activity and enhances the feasibility to broaden the design ideas of transition metalbased catalysts.展开更多
The LiNi 1- y Co y O 2 as cathode material of lithium ion battery was prepared by solid reaction at high temperature and oxygen pressure. The influences of the prepared conditions on electrochemical properties of prod...The LiNi 1- y Co y O 2 as cathode material of lithium ion battery was prepared by solid reaction at high temperature and oxygen pressure. The influences of the prepared conditions on electrochemical properties of products were discussed which include the pressure of oxygen, synthesis time and temperature as well as the molar ratio of the raw materials. The optimal synthetic conditions are as follows: reactive time is 8 h and 10 h; oxygen pressure is 0.20 MPa; reactive temperature is 800 ℃; and molar ratio of the reactants is Li∶Ni∶Co =1.2∶0.9∶0.1. LiNi 0.9 Co 0.1 O 2 was synthesized with the perfect crystal structure and the good electrochemical properties. Its discharged capacity is up to 189.4 mAh/g. The results of X ray diffraction and SEM analysis reveal that the product presents a layered structure of LiNiO 2. The increase of the oxygen pressure during the reactive processes has important effects on the structure and electrochemical properties of the product.展开更多
Cold stress substantially affects plant growth and productivity.Chloroplasts are primary sites for the pro-duction of reactive oxygen species(ROS)and biosynthesis of the defense hormone salicylic acid(SA)under environ...Cold stress substantially affects plant growth and productivity.Chloroplasts are primary sites for the pro-duction of reactive oxygen species(ROS)and biosynthesis of the defense hormone salicylic acid(SA)under environmental stress conditions.However,the mechanisms by which plants integrate ROS and SA signaling to adapt to stress remain elusive.Here,we report that Arabidopsis FILAMENTOUS TEMPERATURE-SENSITIVE H5/YELLOW VARIEGATED1(FtsH5/VAR1),a thylakoid-localized ATP-dependent zinc metalloprotease,is essential for plant cold-stress tolerance.The var1-1 mutant exhibits pronounced chlorosis and variegation,as well as retarded growth under cold stress conditions.We observed a strong correlation between elevated SA biosynthesis/signaling and the cold-sensitive phenotype of var1.Reducing SA accumulation,either by overexpressing the salicylate hydroxylase gene(NahG)or knocking out SA biosynthesis-related genes(ICS1,EDS1,or PAD4),partially suppressed the chlo-rosis phenotype of var1.Furthermore,we demonstrated that EXECUTOR1(EX1)-mediated singlet oxygen(1O2)signaling acts upstream of EDS1 to regulate the expression of SA-responsive genes(SARGs)in var1 under cold stress.Notably,we identified a critical role for EX2,in which the mutation in EX2 significantly suppressed the cold-sensitive phenotype of var1,in activating the expression of SARGs while repressing photosynthesis-associated nuclear genes.Collectively,our results suggest a vital role for VAR1 in plant cold tolerance and highlight the tight connection between ^(1)O_(2) and SA signaling,elucidating a previously unheeded function of EX2,which likely operates independently of EX1-mediated ^(1)O_(2) signaling.展开更多
Magnetic CuO nanosheet(Mag-CuO), as a cheap, stable, efficient and easily separated peroxymonosulfate(PMS) activator, was prepared by a simple one-step precipitation method for the removal of organic compounds from sa...Magnetic CuO nanosheet(Mag-CuO), as a cheap, stable, efficient and easily separated peroxymonosulfate(PMS) activator, was prepared by a simple one-step precipitation method for the removal of organic compounds from salt-containing wastewater.The experiments showed that the removal efficiencies of various organic pollutants including Acid Orange 7, Methylene Blue, Rhodamine B and atrazine in a high-salinity system(0.2 mol/L Na2SO4) with the Mag-CuO/PMS process were 95.81%, 74.57%, 100% and 100%,respectively.Meanwhile, Mag-CuO still maintained excellent catalytic activity in other salt systems including one or more salt components(NaCl, NaNO3, Na2HPO4, NaHCO3).A radical-quenching study and electron paramagnetic resonance analysis confirmed that singlet oxygen(1O2) was the dominant reactive oxygen species for the oxidation of organic pollutants in high-salinity systems, which is less susceptible to hindrance by background constituents in wastewater than radicals(·OH or SO4·-).The surface hydroxylation of the catalyst and catalytic redox cycle including Cu and Fe are responsible for the generation of1O2.The developed Mag-CuO catalyst shows good application prospects for the removal of organic pollutants from saline wastewater.展开更多
Nogo-A is considered one of the most important inhibitors of myelin-associated axonal regeneration in the central nervous system.It is mainly expressed by oligodendrocytes.Although previous studies have found regulato...Nogo-A is considered one of the most important inhibitors of myelin-associated axonal regeneration in the central nervous system.It is mainly expressed by oligodendrocytes.Although previous studies have found regulatory roles for Nogo-A in neurite outgrowth inhibition,neuronal homeostasis,precursor migration,plasticity,and neurodegeneration,its functions in the process of oxidative injury are largely uncharacterized.In this study,oligodendrocytes were extracted from the cerebral cortex of newborn Sprague-Dawley rats.We used hydrogen peroxide(H2O2)to induce an in vitro oligodendrocyte oxidative damage model and found that endogenously expressed Nogo-A is significantly upregulated in oligodendrocytes.After recombinant virus Ad-ZsGreen-rat Nogo-A infection of oligodendrocytes,Nogo-A expression was increased,and the infected oligodendrocytes were more susceptible to acute oxidative insults and exhibited a markedly elevated rate of cell death.Furthermore,knockdown of Nogo-A expression in oligodendrocytes by Ad-ZsGreen-shRNA-Nogo-A almost completely protected against oxidative stress induced by exogenous H2O2.Intervention with a Nogo-66 antibody,a LINGO1 blocker,or Y27632,an inhibitor in the Nogo-66-NgR/p75/LINGO-1-RhoA-ROCK pathway,did not affect the death of oligodendrocytes.Ad-ZsGreen-shRNA-Nogo-A also increased the levels of phosphorylated extracellular signal-regulated kinase 1/2 and inhibited BCL2 expression in oligodendrocytes.In conclusion,Nogo-A aggravated reactive oxygen species damage in oligodendrocytes,and phosphorylated extracellular signal-regulated kinase 1/2 and BCL2 might be involved in this process.This study was approved by the Ethics Committee of Peking University People’s Hospital,China(approval No.2018PHC081)on December 18,2018.展开更多
Oxidative post-translational modifications of specific chloroplast proteins contribute to the initiation of retrograde signaling.The Arabidopsis thaliana EXECUTER1(EX1)protein,a chloroplast-localized singlet oxygen(^(...Oxidative post-translational modifications of specific chloroplast proteins contribute to the initiation of retrograde signaling.The Arabidopsis thaliana EXECUTER1(EX1)protein,a chloroplast-localized singlet oxygen(^(1)O_(2))sensor,undergoes tryptophan(Trp)643 oxidation by^(1)O_(2),a chloroplast-derived and light-dependent reactive oxygen species.The indole side chain of Trp is vulnerable to^(1)O_(2),leading to the generation of oxidized Trp variants and priming EX1 for degradation by a membrane-bound FtsH protease.The perception of^(1)O_(2)via Trp643 oxidation and subsequent EX1 proteolysis facilitate chloroplast-to-nucleus retrograde signaling.In this study,we discovered that the EX1-like protein EX2 also undergoes^(1)O_(2)-dependent Trp530 oxidation and FtsH-dependent turnover,which attenuates^(1)O_(2)signaling by decelerating EX1-Trp643 oxidation and subsequent EX1 degradation.Consistent with this finding,the loss of EX2 function reinforces EX1-dependent retrograde signaling by accelerating EX1-Trp643 oxidation and subsequent EX1 proteolysis,whereas overexpression of EX2 produces molecular phenotypes opposite to those observed in the loss-of-function mutants of EX2.Intriguingly,phylogenetic analysis suggests that EX2 may have emerged evolutionarily to attenuate the sensitivity of EX1 toward^(1)O_(2).Collectively,these results suggest that EX2 functions as a negative regulator of the EX1 signalosome through its own^(1)O_(2)-dependent oxidation,providing a new mechanistic insight into the regulation of EX1-mediated^(1)O_(2)signaling.展开更多
Metal-free heteroatom doped nanocarbons are promising alternatives to the metal-based materials in catalytic ozonation for destruction of aqueous organic contaminants. In this study, N, S co-doped hollow carbon micros...Metal-free heteroatom doped nanocarbons are promising alternatives to the metal-based materials in catalytic ozonation for destruction of aqueous organic contaminants. In this study, N, S co-doped hollow carbon microspheres (NSCs) were synthesized from the polymerization products during persulfate wet air oxidation of benzothiazole. The contents of doped N and S as well as the structural stability were maneuvered by adjusting the subsequent N_(2)-annealing temperature. Compared with the prevailing single-walled carbon nanotubes, the N_(2)-annealed NSCs demonstrated a higher catalytic ozonation activity for benzimidazole degradation. According to the quantitative structure-activity relationship (QSAR) analysis, the synergistic effect between the graphitic N and the thiophene-S which redistributed the charge distribution of the carbon basal plane contributed to the activity enhancement of the N_(2)-annealed NSCs. Additionally, the hollow structure within the microspheres served as the microreactor to boost the mass transfer and reaction kinetics via the nanoconfinement effects. Quenching and electron paramagnetic resonance (EPR) tests revealed that benzimidazole degradation was dominated by the produced singlet oxygen (^(1)O_(2)) species, while hydroxyl radicals (^(·)OH) were also generated and participated. This study puts forward a novel strategy for synthesis of heteroatom-doped nanocarbons and sheds a light on the relationship between the active sites on the doped nanocarbons and the catalytic performance.展开更多
Oxygen reduction reaction(ORR)plays a pivotal role in advanced electrochemical energy conversion devices.However,the ORR conversion efficiency is extremely limited.The major obstacles originate from the adsorption and...Oxygen reduction reaction(ORR)plays a pivotal role in advanced electrochemical energy conversion devices.However,the ORR conversion efficiency is extremely limited.The major obstacles originate from the adsorption and activation of O_(2)on the electrode surface.A novel nanocomposite catalyst,photosensitizers(PS)meso-tetraphenylporphyrin iron(III)chloride(FePcCl)/NiCoFe-layered double hydroxides(NiCoFe-LDHs)is designed in this study.Herein,owing to excellent oxygen molecules activation ability and remarkable illumination absorption feature,FePcCl/NiCoFe-LDHs is employed to uncover the relationship between the intrinsic ORR activity and PS behaviour.Interestingly,the reaction mechanism of singlet 1O_(2)is proposed owing to the combination of electrochemical ORR catalysed via LDHs and PS.The boosted cathodic ORR properties exhibit singlet 1O_(2)dependent response arising from the synergistic effect to selectively produce active intermediates in alkaline medium.This work imparts the promising new mechanism about the high 4-electron ORR selectivity via material design,which will guide the development of photo-assisted energy conversion devices.展开更多
Background: The neutrophils (PMN) are our main blood cells to combat fungi, bacteria, and fibrin. For normal function, an activated PMN generates a certain concentration of reactive oxygen species (ROS). If the genera...Background: The neutrophils (PMN) are our main blood cells to combat fungi, bacteria, and fibrin. For normal function, an activated PMN generates a certain concentration of reactive oxygen species (ROS). If the generated blood ROS concentration is too low, then fungi, bacteria or fibrin might threaten the life of the patient, and it could be of great medical interest to stimulate PMN by physiologic drugs. Granulocyte-Colony Stimulating Factor (G-CSF) is a cell hormone that increases the cell number of PMN and that stimulates the individual PMN. The blood ROS generation assay (BRGA) is an innovative physiologic test to monitor the ROS generation of PMN in blood. Here the ROS generating action of G-CSF on normal PMN is quantified. Material and Methods: 40 μl 0 - 10.3 ng/ml (final conc.) G-CSF (in 5% human albumin) in black Brand? 781608 high quality polystyrene F-microwells was incubated in triplicate with 125 μl Hanks’ balanced salt solution (HBSS;modified without phenol red) and 10 μl normal citrated blood. Immediately (BRGA) or after 60 min (BRGA-60-) 10 μl 5 mM luminol sodium salt in 0.9% NaCl and 10 μl 0 or 36 μg/ml zymosan A in 0.9% NaCl was added. The photons were counted within 0 - 318 min (37°C) in a photons-multiplying microtiter plate luminometer. At about 0.5 t-maxn (0.5 fold the time to normal maximum) the approx. SC200 of G-CSF was determined. Results and Discussion: The approx. SC200 of G-CSF on normal blood ROS generation was 0.2 μg/l (=20 IU/ml). In clinical situations where an increased blood ROS generation is pharmacologically required, few micrograms of G-CSF could be a sufficient dosage for an adult patient. The BRGA helps to find out the correct stimulating G-CSF dosage for each individual. An enhanced PMN function could favor a better clinical outcome in situations of wanted increase of the innate immunology or in cellular fibrinolysis. G-CSF plasma concentrations of 0.1 - 1 μg/l might favor singlet oxygen generation without immunosuppression or cell fragment-induced thrombin generation.展开更多
Investigation of the substitution process can provide a better understanding of the superconducting mechanisms in cuprous oxide materials. In this work the effects of substitution Lanthanum (La) for Gadolinium (Gd) on...Investigation of the substitution process can provide a better understanding of the superconducting mechanisms in cuprous oxide materials. In this work the effects of substitution Lanthanum (La) for Gadolinium (Gd) on the structure and oxygen content for x = 0.0 - 0.5 in the compound Gd1-xLaxBa2Cu3O7-δ (GLBCO-123 phase) have been investigated. Samples were synthesized by using a wet-mixing method from powders of Gd2O2, La2O2, BaO, CuO, and solution of HNO3. Based on the analysis of XRD data and SEM-EDXA, it confirms that the sample has formed the GLBCO-123 phase, as expected. It has been obtained that the lattice parameters a and c are increased while the parameter b is slightly decreased with increasing content of Lanthanum. The oxygen content slightly decreased and structure of the Gd1-xLaxBa2Cu3O7-δ phase changed from orthorhombic to tetragonal with increasing the content of Lanthanum.展开更多
文摘Methylene blue sensitized singlet oxygen oxidation of dl-α-tocopherol in dodecylsulfate (SDS) or cetyl trimethyl ammonium brondde (CTAB) ndcelles led to the formation, besidesα-tocopherol quinone and its epoxide, of a hitherto unknown spiro compound 6-hydroxy-2,6,8,9-tetramethyl-2-phytyl- 1-oxaspiro [4, 5] dec -8 - en - 7, 10-dione.
基金financially supported by the National Key Research and Development Program of China(No.2018YFA0703700)the National Natural Science Foundation of China(Nos.12004031,12034002 and 51971025)+3 种基金Beijing Natural Science Foundation(No.2212034)Foshan Talents Special Foundation(No.BKBS202003)the Scientific and Technological Innovation Foundation of Foshan(No.BK22BE005)Foshan Science and Technology Innovation Project(No.2018IT100363)。
文摘For catalytic materials,the characteristics of one-dimension and hollowness are the promotion factors for their full presentation of catalytic activity,and through a template-as sis ted method,both above superiorities can be fused simultaneously.Here,we proposed a novel strategy inspired by Pearson's principle with Cu_(2)O wires as templates,and prepared FeOOH hollow tubes,which covered by FeOOH scales.When applied as oxygen evolution reaction(OER)catalyst,the FeOOH scaly hollow tubes(FeOOH SHTs)showed outstanding catalytic activity with a low overpotential of 245 mV to drive a current density of10 mA·cm^(-2),excellent kinetics manifesting as a low Tafel slope of 46.9 mV·dec^(-1),and robust stability.This work provides a new synthesis strategy for an ideal OER catalyst,FeOOH,with high inherent activity and enhances the feasibility to broaden the design ideas of transition metalbased catalysts.
文摘The LiNi 1- y Co y O 2 as cathode material of lithium ion battery was prepared by solid reaction at high temperature and oxygen pressure. The influences of the prepared conditions on electrochemical properties of products were discussed which include the pressure of oxygen, synthesis time and temperature as well as the molar ratio of the raw materials. The optimal synthetic conditions are as follows: reactive time is 8 h and 10 h; oxygen pressure is 0.20 MPa; reactive temperature is 800 ℃; and molar ratio of the reactants is Li∶Ni∶Co =1.2∶0.9∶0.1. LiNi 0.9 Co 0.1 O 2 was synthesized with the perfect crystal structure and the good electrochemical properties. Its discharged capacity is up to 189.4 mAh/g. The results of X ray diffraction and SEM analysis reveal that the product presents a layered structure of LiNiO 2. The increase of the oxygen pressure during the reactive processes has important effects on the structure and electrochemical properties of the product.
基金supported by grants from the National Natural Science Foundation of China(NSFC,32270285 and 32470290)the 111 Project of the Ministry of Education of China(B23033)+1 种基金the Shanghai Collaborative Innovation Center of Agri-Seeds(ZXWH2150201/022)the Partner Group Program of The Max Planck Society to G.-Z.W.
文摘Cold stress substantially affects plant growth and productivity.Chloroplasts are primary sites for the pro-duction of reactive oxygen species(ROS)and biosynthesis of the defense hormone salicylic acid(SA)under environmental stress conditions.However,the mechanisms by which plants integrate ROS and SA signaling to adapt to stress remain elusive.Here,we report that Arabidopsis FILAMENTOUS TEMPERATURE-SENSITIVE H5/YELLOW VARIEGATED1(FtsH5/VAR1),a thylakoid-localized ATP-dependent zinc metalloprotease,is essential for plant cold-stress tolerance.The var1-1 mutant exhibits pronounced chlorosis and variegation,as well as retarded growth under cold stress conditions.We observed a strong correlation between elevated SA biosynthesis/signaling and the cold-sensitive phenotype of var1.Reducing SA accumulation,either by overexpressing the salicylate hydroxylase gene(NahG)or knocking out SA biosynthesis-related genes(ICS1,EDS1,or PAD4),partially suppressed the chlo-rosis phenotype of var1.Furthermore,we demonstrated that EXECUTOR1(EX1)-mediated singlet oxygen(1O2)signaling acts upstream of EDS1 to regulate the expression of SA-responsive genes(SARGs)in var1 under cold stress.Notably,we identified a critical role for EX2,in which the mutation in EX2 significantly suppressed the cold-sensitive phenotype of var1,in activating the expression of SARGs while repressing photosynthesis-associated nuclear genes.Collectively,our results suggest a vital role for VAR1 in plant cold tolerance and highlight the tight connection between ^(1)O_(2) and SA signaling,elucidating a previously unheeded function of EX2,which likely operates independently of EX1-mediated ^(1)O_(2) signaling.
基金supported by the National Water Pollution Control and Management Program of China (No.2017ZX07107002).
文摘Magnetic CuO nanosheet(Mag-CuO), as a cheap, stable, efficient and easily separated peroxymonosulfate(PMS) activator, was prepared by a simple one-step precipitation method for the removal of organic compounds from salt-containing wastewater.The experiments showed that the removal efficiencies of various organic pollutants including Acid Orange 7, Methylene Blue, Rhodamine B and atrazine in a high-salinity system(0.2 mol/L Na2SO4) with the Mag-CuO/PMS process were 95.81%, 74.57%, 100% and 100%,respectively.Meanwhile, Mag-CuO still maintained excellent catalytic activity in other salt systems including one or more salt components(NaCl, NaNO3, Na2HPO4, NaHCO3).A radical-quenching study and electron paramagnetic resonance analysis confirmed that singlet oxygen(1O2) was the dominant reactive oxygen species for the oxidation of organic pollutants in high-salinity systems, which is less susceptible to hindrance by background constituents in wastewater than radicals(·OH or SO4·-).The surface hydroxylation of the catalyst and catalytic redox cycle including Cu and Fe are responsible for the generation of1O2.The developed Mag-CuO catalyst shows good application prospects for the removal of organic pollutants from saline wastewater.
基金This work was supported by the National Natural Science Foundation of China,No.81870996(to JZ).
文摘Nogo-A is considered one of the most important inhibitors of myelin-associated axonal regeneration in the central nervous system.It is mainly expressed by oligodendrocytes.Although previous studies have found regulatory roles for Nogo-A in neurite outgrowth inhibition,neuronal homeostasis,precursor migration,plasticity,and neurodegeneration,its functions in the process of oxidative injury are largely uncharacterized.In this study,oligodendrocytes were extracted from the cerebral cortex of newborn Sprague-Dawley rats.We used hydrogen peroxide(H2O2)to induce an in vitro oligodendrocyte oxidative damage model and found that endogenously expressed Nogo-A is significantly upregulated in oligodendrocytes.After recombinant virus Ad-ZsGreen-rat Nogo-A infection of oligodendrocytes,Nogo-A expression was increased,and the infected oligodendrocytes were more susceptible to acute oxidative insults and exhibited a markedly elevated rate of cell death.Furthermore,knockdown of Nogo-A expression in oligodendrocytes by Ad-ZsGreen-shRNA-Nogo-A almost completely protected against oxidative stress induced by exogenous H2O2.Intervention with a Nogo-66 antibody,a LINGO1 blocker,or Y27632,an inhibitor in the Nogo-66-NgR/p75/LINGO-1-RhoA-ROCK pathway,did not affect the death of oligodendrocytes.Ad-ZsGreen-shRNA-Nogo-A also increased the levels of phosphorylated extracellular signal-regulated kinase 1/2 and inhibited BCL2 expression in oligodendrocytes.In conclusion,Nogo-A aggravated reactive oxygen species damage in oligodendrocytes,and phosphorylated extracellular signal-regulated kinase 1/2 and BCL2 might be involved in this process.This study was approved by the Ethics Committee of Peking University People’s Hospital,China(approval No.2018PHC081)on December 18,2018.
基金This research was supported by the Strategic Priority Research Program from the Chinese Academy of Sciences(grant no.XDB27040102)the 100-Talent Program of the Chinese Academy of Sciences and the National Natural Science Foundation of China(NSFC)(grant no.31871397)to C.K.Support from a President's International Fellowship Initiative(PIFI)postdoctoral fellowship from the Chinese Academy of Sciences(no.2019PB0066)to V.D.is also acknowledged.
文摘Oxidative post-translational modifications of specific chloroplast proteins contribute to the initiation of retrograde signaling.The Arabidopsis thaliana EXECUTER1(EX1)protein,a chloroplast-localized singlet oxygen(^(1)O_(2))sensor,undergoes tryptophan(Trp)643 oxidation by^(1)O_(2),a chloroplast-derived and light-dependent reactive oxygen species.The indole side chain of Trp is vulnerable to^(1)O_(2),leading to the generation of oxidized Trp variants and priming EX1 for degradation by a membrane-bound FtsH protease.The perception of^(1)O_(2)via Trp643 oxidation and subsequent EX1 proteolysis facilitate chloroplast-to-nucleus retrograde signaling.In this study,we discovered that the EX1-like protein EX2 also undergoes^(1)O_(2)-dependent Trp530 oxidation and FtsH-dependent turnover,which attenuates^(1)O_(2)signaling by decelerating EX1-Trp643 oxidation and subsequent EX1 degradation.Consistent with this finding,the loss of EX2 function reinforces EX1-dependent retrograde signaling by accelerating EX1-Trp643 oxidation and subsequent EX1 proteolysis,whereas overexpression of EX2 produces molecular phenotypes opposite to those observed in the loss-of-function mutants of EX2.Intriguingly,phylogenetic analysis suggests that EX2 may have emerged evolutionarily to attenuate the sensitivity of EX1 toward^(1)O_(2).Collectively,these results suggest that EX2 functions as a negative regulator of the EX1 signalosome through its own^(1)O_(2)-dependent oxidation,providing a new mechanistic insight into the regulation of EX1-mediated^(1)O_(2)signaling.
基金financial supports from the National Natural Science Foundation of China (No21978324)Tianjin Municipal Science and Technology Bureau (No.18YFYSZ00170)+1 种基金Beijing Natural Science Foundation (No. 8192039)Science Foundation of China University of Petroleum,Beijing(No. 2462020YXZZ034)。
文摘Metal-free heteroatom doped nanocarbons are promising alternatives to the metal-based materials in catalytic ozonation for destruction of aqueous organic contaminants. In this study, N, S co-doped hollow carbon microspheres (NSCs) were synthesized from the polymerization products during persulfate wet air oxidation of benzothiazole. The contents of doped N and S as well as the structural stability were maneuvered by adjusting the subsequent N_(2)-annealing temperature. Compared with the prevailing single-walled carbon nanotubes, the N_(2)-annealed NSCs demonstrated a higher catalytic ozonation activity for benzimidazole degradation. According to the quantitative structure-activity relationship (QSAR) analysis, the synergistic effect between the graphitic N and the thiophene-S which redistributed the charge distribution of the carbon basal plane contributed to the activity enhancement of the N_(2)-annealed NSCs. Additionally, the hollow structure within the microspheres served as the microreactor to boost the mass transfer and reaction kinetics via the nanoconfinement effects. Quenching and electron paramagnetic resonance (EPR) tests revealed that benzimidazole degradation was dominated by the produced singlet oxygen (^(1)O_(2)) species, while hydroxyl radicals (^(·)OH) were also generated and participated. This study puts forward a novel strategy for synthesis of heteroatom-doped nanocarbons and sheds a light on the relationship between the active sites on the doped nanocarbons and the catalytic performance.
基金the financial support from the Major State Basic Research Development Program of China(973 Program)(No.2014CB932101)the National Natural Science Foundation of China(Nos.21571013 and 52073023)Program for Chang Jiang Scholars and Innovative Research Team in University(No.IRT1205).
文摘Oxygen reduction reaction(ORR)plays a pivotal role in advanced electrochemical energy conversion devices.However,the ORR conversion efficiency is extremely limited.The major obstacles originate from the adsorption and activation of O_(2)on the electrode surface.A novel nanocomposite catalyst,photosensitizers(PS)meso-tetraphenylporphyrin iron(III)chloride(FePcCl)/NiCoFe-layered double hydroxides(NiCoFe-LDHs)is designed in this study.Herein,owing to excellent oxygen molecules activation ability and remarkable illumination absorption feature,FePcCl/NiCoFe-LDHs is employed to uncover the relationship between the intrinsic ORR activity and PS behaviour.Interestingly,the reaction mechanism of singlet 1O_(2)is proposed owing to the combination of electrochemical ORR catalysed via LDHs and PS.The boosted cathodic ORR properties exhibit singlet 1O_(2)dependent response arising from the synergistic effect to selectively produce active intermediates in alkaline medium.This work imparts the promising new mechanism about the high 4-electron ORR selectivity via material design,which will guide the development of photo-assisted energy conversion devices.
文摘Background: The neutrophils (PMN) are our main blood cells to combat fungi, bacteria, and fibrin. For normal function, an activated PMN generates a certain concentration of reactive oxygen species (ROS). If the generated blood ROS concentration is too low, then fungi, bacteria or fibrin might threaten the life of the patient, and it could be of great medical interest to stimulate PMN by physiologic drugs. Granulocyte-Colony Stimulating Factor (G-CSF) is a cell hormone that increases the cell number of PMN and that stimulates the individual PMN. The blood ROS generation assay (BRGA) is an innovative physiologic test to monitor the ROS generation of PMN in blood. Here the ROS generating action of G-CSF on normal PMN is quantified. Material and Methods: 40 μl 0 - 10.3 ng/ml (final conc.) G-CSF (in 5% human albumin) in black Brand? 781608 high quality polystyrene F-microwells was incubated in triplicate with 125 μl Hanks’ balanced salt solution (HBSS;modified without phenol red) and 10 μl normal citrated blood. Immediately (BRGA) or after 60 min (BRGA-60-) 10 μl 5 mM luminol sodium salt in 0.9% NaCl and 10 μl 0 or 36 μg/ml zymosan A in 0.9% NaCl was added. The photons were counted within 0 - 318 min (37°C) in a photons-multiplying microtiter plate luminometer. At about 0.5 t-maxn (0.5 fold the time to normal maximum) the approx. SC200 of G-CSF was determined. Results and Discussion: The approx. SC200 of G-CSF on normal blood ROS generation was 0.2 μg/l (=20 IU/ml). In clinical situations where an increased blood ROS generation is pharmacologically required, few micrograms of G-CSF could be a sufficient dosage for an adult patient. The BRGA helps to find out the correct stimulating G-CSF dosage for each individual. An enhanced PMN function could favor a better clinical outcome in situations of wanted increase of the innate immunology or in cellular fibrinolysis. G-CSF plasma concentrations of 0.1 - 1 μg/l might favor singlet oxygen generation without immunosuppression or cell fragment-induced thrombin generation.
文摘Investigation of the substitution process can provide a better understanding of the superconducting mechanisms in cuprous oxide materials. In this work the effects of substitution Lanthanum (La) for Gadolinium (Gd) on the structure and oxygen content for x = 0.0 - 0.5 in the compound Gd1-xLaxBa2Cu3O7-δ (GLBCO-123 phase) have been investigated. Samples were synthesized by using a wet-mixing method from powders of Gd2O2, La2O2, BaO, CuO, and solution of HNO3. Based on the analysis of XRD data and SEM-EDXA, it confirms that the sample has formed the GLBCO-123 phase, as expected. It has been obtained that the lattice parameters a and c are increased while the parameter b is slightly decreased with increasing content of Lanthanum. The oxygen content slightly decreased and structure of the Gd1-xLaxBa2Cu3O7-δ phase changed from orthorhombic to tetragonal with increasing the content of Lanthanum.
