Idiosyncratic hepatotoxicity accounts for many drug failures in the clinic and is a leading cause for black-boxed and withdrawn drugs. This toxicity has proven difficult to predict preclinically, but correlates with o...Idiosyncratic hepatotoxicity accounts for many drug failures in the clinic and is a leading cause for black-boxed and withdrawn drugs. This toxicity has proven difficult to predict preclinically, but correlates with oxidative stress/reactive metabolites (OS/RM). As noted previously for antiepileptic compounds, many drugs causing idiosyncratic adverse drug effects are detected by OS/RM gene expression responses in the rat. In the present study, two immune activation models, low dose lipopolysaccharide (1 mg/kg IV) and 5% dextran sulphate sodium (DSS) in drinking water, were examined to determine if either would convert the non-toxic idiosyncratic toxicant carbamazepine (225 mg/kg) into a rat hepatotoxicant at 24 hours. Using the low dose LPS model, about 1/3 of the carbamazepine-treated rats either showed robust ALT and AST elevations with histopathological evidence of hepatotoxicity, or died. Rats in this LPS/carbamazepine group were subdivided based on ALT values into non-responders, responders or robust responders. Whereas most carbamazepine-induced mRNAs were repressed by LPS across all rats in this group, the OS/ RM genes aflatoxin aldehyde reductase (Afar) and glutathione transferase Ya (Gstya) were repressed only in the robust responder subgroup;it is unclear whether repression of these genes contributes to or results from hepatotoxicity. The OS/RM gene microsomal epoxide hydrolase (mEphx) showed repression across all rats. NAD(P)H: menadione oxidoreductase (Nmor) is an OS/RM-responsive gene that is also induced by LPS, confounding interpretation of its changes. After pretreatment with 5% DSS at 24 hours or for 5 days, using a protocol that reportedly produces increased endotoxin absorption, carbamazepine was not converted to a hepatototoxicant in any rats. Instead, DSS produced a pronounced (2- to 6-fold) and selective potentiation of carbamazepine induction of OS/RM-responsive mRNAs. The lack of repressive effects of DSS on these mRNAs or in converting carbamazepine to a hepatotoxicant was not due to desensitization of endotoxin responses since LPS was at least as effective when administered to DSS-pretreated rats. OS/RM gene repression may contribute to development of hepatotoxicity of carbamazepine in immune activation models.展开更多
The reactive materials filled structure(RMFS)is a structural penetrator that replaces high explosive(HE)with reactive materials,presenting a novel self-distributed initiation,multiple deflagrations behavior during pen...The reactive materials filled structure(RMFS)is a structural penetrator that replaces high explosive(HE)with reactive materials,presenting a novel self-distributed initiation,multiple deflagrations behavior during penetrating multi-layered plates,and generating a multipeak overpressure behind the plates.Here analytical models of RMFS self-distributed energy release and equivalent deflagration are developed.The multipeak overpressure formation model based on the single deflagration overpressure expression was promoted.The impact tests of RMFS on multi-layered plates at 584 m/s,616 m/s,and819 m/s were performed to validate the analytical model.Further,the influence of a single overpressure peak and time intervals versus impact velocity is discussed.The analysis results indicate that the deflagration happened within 20.68 mm behind the plate,the initial impact velocity and plate thickness are the crucial factors that dominate the self-distributed multipeak overpressure effect.Three formation patterns of multipeak overpressure are proposed.展开更多
Reactive compatibilization has been widely applied to enhance the compatibility of polymer blends,thereby improving their mechanical properties.However,it generally reduces the chain mobility and regularity,often lead...Reactive compatibilization has been widely applied to enhance the compatibility of polymer blends,thereby improving their mechanical properties.However,it generally reduces the chain mobility and regularity,often leading to slower polymer crystallization.Here,we demonstrate that reactive compatibilization in poly(lactic acid)/poly(butylene adipate-co-terephthalate)(PLA/PBAT)blends unexpectedly promotes PLA matrix crystallization during injection molding,in contrast to the retarded kinetics observed in differential scanning calorimetry isothermal crystallization studies.The phase morphology,rheological behavior,and crystalline structure were systematically analyzed to elucidate markedly different crystallization kinetics under static and shear fields.The potential mechanism underlying crystallization enhancement is attributed to PBAT domain refinement and viscosity increase induced by reactive compatibilization,which,under shear flow,create favorable conditions for crystallization by enhancing PBAT fibril nucleation and retarding the relaxation of oriented PLA chains.This study offers new perspectives on the effect of reactive compatibilization on the polymer crystallization behavior.展开更多
Rubber-toughened thermoplastic materials have become ubiquitous in modern society owing to their lightweight nature and desirable combination of advantageous performances.Despite the ever-increasing demand,the develop...Rubber-toughened thermoplastic materials have become ubiquitous in modern society owing to their lightweight nature and desirable combination of advantageous performances.Despite the ever-increasing demand,the development of polymer alloys that are lightweight,high-strength,and high-toughness remains an ongoing challenge.Inspired by the unique“salami”microstructure from commercial acrylonitrile butadiene styrene copolymer(ABS)and high-impact polystyrene(HIPS),a facile approach was developed to overcome the trade-off between enhancing the toughness and rigidity of fully polymer-based alloys by virtue of elastomeric salami particles.This strategy entails pre-grafting rigid poly(lactic acid)(PLLA)chains with glycidyl methacrylate-grafted octene ethylene copolymer(POE-g-GMA)using complementary reactive groups.It can be envisaged that the PLLA grafts featuring strong incompatibility with polypropylene(PP)remain fixed in elastomer phase upon the subsequent melt compounding,facilitating the in situ formation of“hard core(PLLA)-soft shell(polyolefin elastomer,POE)”particles in polypropylene(PP)matrix.The all-polymer alloys containing elastomeric salami particles demonstrated unprecedented performance combinations,including upper notched impact strengths(56.8 kJ/m2),even higher tensile strength(36.8 MPa),and Young’s modulus(0.93 GPa)than that of the PP matrix.Furthermore,these materials are lightweight without the incorporation of reinforcing nano-fillers,which is competitive with industrial engineering plastics.It is highly anticipated that this universal and highly efficient protocol will be appropriate for arbitrary rubber toughened/reinforced systems,offering a paradigm in the design of advanced all-polymer alloys.展开更多
Biochar and zero-valent iron are promising materials for the removal of trichloroethylene(TCE)from groundwater,but further research is still required on the synergistic mechanism and hydraulic performance in the perme...Biochar and zero-valent iron are promising materials for the removal of trichloroethylene(TCE)from groundwater,but further research is still required on the synergistic mechanism and hydraulic performance in the permeable reactive barriers(PRBs)with biochar-iron composites.In this work,biochar-iron composites were synthesized by two different methods,and subjected to the microscopic analysis,batch experiments and the PRB’s model tests.The results indicated that the removal rates of TCE on biochar-iron composites reached above 90%,and the optimal removal conditions were the initial pH of 6.0 and a biochar/iron mass ratio of 5:1.The removal of TCE on biochar-iron composites followed the pseudo-second-order and Freundlich models,and the maximum adsorption capacity of TCE was 25.95 mg/g.The adsorption of biochar and dechlorination of nZVI dominated the removal of TCE.Biochar significantly enhanced the dechlorination of TCE on nZVI through modifying the electrochemical characteristics to lower its corrosion potential of nZVI,promote direct electron transfer,and improve electronic transfer capability.M-5BC-1nZVI exhibited excellent hydraulic performance for maintaining an adequate permeability coefficient(10^(−6)to 10^(−5)m/s).展开更多
Achieving high selectivity to 2,5-furandicarboxylic acid(FDCA)in the photocatalytic oxidation of 5-hydroxymethylfurfural(HMF)in aqueous solution advocates the principle of green and sustainable chemistry,but still rem...Achieving high selectivity to 2,5-furandicarboxylic acid(FDCA)in the photocatalytic oxidation of 5-hydroxymethylfurfural(HMF)in aqueous solution advocates the principle of green and sustainable chemistry,but still remains a significant challenge.Herein,manipulating the reactive oxygen species(ROS)has been realized and dramatically promotes the selective photocatalytic oxidation of HMF in aqueous solution.A high FDCAyield of 98.6% has been achieved after 3 h of visible light irradiation over the as-prepared FeO_(x)-Au/TiO_(2) catalyst,being one of the leading photocatalytic performances.Furthermore,satisfactory FDCA yields of higher than 80%could be realized even in the outdoor environment under natural sunlight irradiation,regardless of sunny or cloudy weather.A combination study including physical characterization,kinetic analysis,radical trapping experiments and density functional theory calculations unveils the rate-determining step(oxidation of hydroxyl group)and respective contributions of the generated ROS(1O_(2) and·O_(2)-)in each step of the entire reaction network.The present work would push ahead the understanding of HMF photocatalytic oxidation and contribute to the rational design of high-performance photocatalysts.展开更多
We are sorry for the mistakes of Affiliation,"a State Key Laboratory of Advanced Fiber Materials,Center for Advanced Low-Dimension Materials,Donghua University,Shanghai 201620,China"should be replaced by&quo...We are sorry for the mistakes of Affiliation,"a State Key Laboratory of Advanced Fiber Materials,Center for Advanced Low-Dimension Materials,Donghua University,Shanghai 201620,China"should be replaced by"a State Key Laboratory of Advanced Fiber Materials,Center for Advanced Low-Dimension Materials,College of Materials Science and Engineering,Donghua University,Shanghai 201620,China".We apologized for the inconvenience caused by this error.展开更多
In real industrial microgrids(MGs),the length of the primary delivery feeder to the connection point of the main substation is sometimes long.This reduces the power factor and increases reactive power absorption along...In real industrial microgrids(MGs),the length of the primary delivery feeder to the connection point of the main substation is sometimes long.This reduces the power factor and increases reactive power absorption along the primary delivery feeder from the external network.Besides,the giant induction electro-motors as the working horse of industries requires remarkable amounts of reactive power for electro-mechanical energy conversions.To reduce power losses and operating costs of the MG as well as to improve the voltage quality,this study aims at providing an insightful model for optimal placement and sizing of reactive power compensation capacitors in an industrial MG.In the presented model,the objective function considers voltage profile and network power factor improvement at the MG connection point.Also,it realizes power flow equations within which all operational security constraints are considered.Various reactive power compensation strategies including distributed group compensation,centralized compensation at the main substation,and distributed compensation along the primary delivery feeder are scrutinized.A real industrial MG,say as Urmia Petrochemical plant,is considered in numerical validations.The obtained results in each scenario are discussed in depth.As seen,the best performance is obtained when the optimal location and sizing of capacitors are simultaneously determined at the main buses of the industrial plants,at the main substation of the MG,and alongside the primary delivery feeder.In this way,74.81%improvement in power losses reduction,1.3%lower active power import from the main grid,23.5%improvement in power factor,and 37.5%improvement in network voltage deviation summation are seen in this case compared to the base case.展开更多
Enhanced UV-B radiation represents a major environmental factor impacting global cereal production.Researchers have explored various approaches to reduce the detrimental impact of UV-B radiation on crops.Recently,engi...Enhanced UV-B radiation represents a major environmental factor impacting global cereal production.Researchers have explored various approaches to reduce the detrimental impact of UV-B radiation on crops.Recently,engineered nanoparticles,particularly cerium oxide nanoparticles(CeO_(2)-NPs),have attracted widespread interest for their ability to boost plant tolerance to a range of abiotic stresses.This study investigates how CeO_(2)-NPs application affects the morphology,physiology,biochemistry,and transcriptomics profiles of wheat seedling roots subjected to enhanced UV-B stress.The findings demonstrate that CeO_(2)-NPs notably promoted root length,fresh and dry weights,and root activity(p<0.05)under enhanced UV-B stress.CeO_(2)-NP treatment reduced the content of hydrogen peroxide<(H_(2)O_(2))and malondialdehyde(MDA)in wheat,alleviating oxidative damage in seedling roots and partially restoring the root phenotype.Under non-UV-B stress conditions,CeO_(2)-NP treatment triggered the difference of 237 transcripts in plants relative to the control group.Under enhanced UV-B stress,CeO_(2)-NP treatment exhibited differentially expressed genes(DEGs)linked to the antioxidant defense mechanism responsible for reactive oxygen species(ROS)scavenging,compared to the non-nanoparticle control.This suggests that ROS scavenging may be a key mechanism by which CeO_(2)-NPs enhance wheat resistance to enhanced UV-B radiation.This study elucidates a potential molecular mechanism through which CeO_(2)nanoparticles may enhance wheat tolerance to UV-B stress.展开更多
An optimized volt-ampere reactive(VAR)control framework is proposed for transmission-level power systems to simultaneously mitigate voltage deviations and active-power losses through coordinated control of large-scale...An optimized volt-ampere reactive(VAR)control framework is proposed for transmission-level power systems to simultaneously mitigate voltage deviations and active-power losses through coordinated control of large-scale wind/solar farms with shunt static var generators(SVGs).The model explicitly represents reactive-power regulation characteristics of doubly-fed wind turbines and PV inverters under real-time meteorological conditions,and quantifies SVG high-speed compensation capability,enabling seamless transition from localized VAR management to a globally coordinated strategy.An enhanced adaptive gain-sharing knowledge optimizer(AGSK-SD)integrates simulated annealing and diversity maintenance to autonomously tune voltage-control actions,renewable source reactive-power set-points,and SVG output.The algorithm adaptively modulates knowledge factors and ratios across search phases,performs SA-based fine-grained local exploitation,and periodically re-injects population diversity to prevent premature convergence.Comprehensive tests on IEEE 9-bus and 39-bus systems demonstrate AGSK-SD’s superiority over NSGA-II and MOPSO in hypervolume(HV),inverse generative distance(IGD),and spread metrics while maintaining acceptable computational burden.The method reduces network losses from 2.7191 to 2.15 MW(20.79%reduction)and from 15.1891 to 11.22 MW(26.16%reduction)in the 9-bus and 39-bus systems respectively.Simultaneously,the cumulative voltage-deviation index decreases from 0.0277 to 3.42×10^(−4) p.u.(98.77%reduction)in the 9-bus system,and from 0.0556 to 0.0107 p.u.(80.76%reduction)in the 39-bus system.These improvements demonstrate significant suppression of line losses and voltage fluctuations.Comparative analysis with traditional heuristic optimization algorithms confirms the superior performance of the proposed approach.展开更多
Background:Theworld is nowexperiencing many crises and adversities of great impact that pose serious threats to both physical and mental health.Threats to mental health include major depressive disorder,which can be s...Background:Theworld is nowexperiencing many crises and adversities of great impact that pose serious threats to both physical and mental health.Threats to mental health include major depressive disorder,which can be severe and disabling.The current study aimed to identify the prevalence of one type of depressive disorder,reactive depression(RD),and its relationship to demographic and psychological variables.Methods:For this study,RD is defined as an abnormal emotional response to traumatic situations involving mood difficulties.This study created an online self-report reactive depression questionnaire consisting of 23 items distributed across three subscales:1)bad feelings and life attitudes,2)loss of hope and loneliness,and 3)feeling sad and loss of confidence.The questionnaire was administered to a volunteer sample of 362male and female Iraqi university students.Exploratory Factor Analysis(EFA),Confirmatory Factor Analysis(CFA),t-tests,and one-way Analysis of Variance(ANOVA)were used to investigate exploratory and confirmatory factor structures of the questionnaire.Results:Evidence of reactive depression was found in 18.2%of the students.Female students had significantly higher levels of reactive depression than males(female N=205,mean=85.00,SD=11.30;male N=157,mean=76.46,SD=11.51).The high levels of reactive depression identified in these students demonstrate the value of assessing reactive depression in university students.Conclusion:The study underscores that the loss of emotional and psychological security,particularly in the face of traumatic and permanent events such as the death of a loved one,may contribute to the onset and progression of depressive symptoms.Future research should explore the role of specific cultural factors and further validate the reactive depression questionnaire in broader populations.Additionally,there is a need for improvedmental health support in Iraqi universities,particularly for female students,who may face unique challenges.展开更多
Effects of sodium nitroprusside (SNP), a nitric oxide (NO) donor, on the germination and metabolism of reactive oxygen species were surveyed in wheat (Triticum aestivum L.) seeds. Germination of wheat seeds and even t...Effects of sodium nitroprusside (SNP), a nitric oxide (NO) donor, on the germination and metabolism of reactive oxygen species were surveyed in wheat (Triticum aestivum L.) seeds. Germination of wheat seeds and even the elongation of radicle and plumule were dramatically promoted by SNP treatments during the germination under osmotic stress. Meanwhile, activities of amylase and EP were enhanced, thus leading to the degradation of storage reserve in seeds. After osmotic stress was removed, higher viability of wheat seeds was also maintained. In addition, the activities of CAT, APX and the content of proline were increased by SNP treatment simultaneously, but activities of LOX were inhibited, and both of which were beneficial for improving the antioxidant capacity during the germination of wheat seeds under osmotic stress. It was also shown that the increase of the activity of amylase induced by SNP in embryoless half-seeds of wheat in the beginning period of germination (6 h) might be indirectly related to GA(3).展开更多
AIM: To investigate the effects of N-acetylcysteine (NAC) on endoplasmic reticulum (ER) stress and tissue injury during liver ischemia reperfusion injury (IRI).
Rice is one of the main staple food crops in the world, but it may suffer serious water stress during growth period. Water stress during grain filling results in decreased grain yeild, but its mechanism generating and...Rice is one of the main staple food crops in the world, but it may suffer serious water stress during growth period. Water stress during grain filling results in decreased grain yeild, but its mechanism generating and scavenging the active oxygen is unclear under continuance of the water stress. The experiment was carried out in growth chamber to investigate the effects of water stress on the production of superoxide free radical （O2）, hydrogen peroxide （H202）, malondialdehyde （MDA）, reduced glutathione （GSH）, ascorbic acid （AsA）, and antioxidative enzyme activities in three rice hybrids with differing drought resistant under both normal and drought conditions during grain-filling stage. The results showed that water stress aggravated the membrane lipid peroxidation in rice leaves, which was more severe in less drought resistant hybrids than that in more tolerant ones. Also O2＇ and H2O2 accumulated more rapidly in less drought resistant hybrids than that in more tolerant ones. During water stress, decreases of GSH, AsA, chlorophyll, and relative water contents in more drought resistant hybrids were obvious less than those in less tolerant ones. Activities of superoxide dismutase （SOD）, catalase （CAT） and peroxidase （POD） in/eaves increased obviously in 0-14 d after heading and subsequently decreased rapidly, and those in more drought resistant hybrids were more than those in less tolerant ones. The results showed that changes of O2, H2O2, MDA, GSH, and AsA contents and antioxidative enzyme activities correlated significantly to drought resistance of rice hybrids, and more drought resistant hybrids possessed high ant oxidation capacity.展开更多
Astrocytes are the most abundant type of glial cell in the central nervous system.Upon injury and inflammation,astrocytes become reactive and undergo morphological and functional changes.Depending on their phenotypic ...Astrocytes are the most abundant type of glial cell in the central nervous system.Upon injury and inflammation,astrocytes become reactive and undergo morphological and functional changes.Depending on their phenotypic classification as A1 or A2,reactive astrocytes contribute to both neurotoxic and neuroprotective responses,respectively.However,this binary classification does not fully capture the diversity of astrocyte responses observed across different diseases and injuries.Transcriptomic analysis has revealed that reactive astrocytes have a complex landscape of gene expression profiles,which emphasizes the heterogeneous nature of their reactivity.Astrocytes actively participate in regulating central nervous system inflammation by interacting with microglia and other cell types,releasing cytokines,and influencing the immune response.The phosphoinositide 3-kinase(PI3K)/protein kinase B(AKT)signaling pathway is a central player in astrocyte reactivity and impacts various aspects of astrocyte behavior,as evidenced by in silico,in vitro,and in vivo results.In astrocytes,inflammatory cues trigger a cascade of molecular events,where nuclear factor-κB serves as a central mediator of the pro-inflammatory responses.Here,we review the heterogeneity of reactive astrocytes and the molecular mechanisms underlying their activation.We highlight the involvement of various signaling pathways that regulate astrocyte reactivity,including the PI3K/AKT/mammalian target of rapamycin(mTOR),αvβ3 integrin/PI3K/AKT/connexin 43,and Notch/PI3K/AKT pathways.While targeting the inactivation of the PI3K/AKT cellular signaling pathway to control reactive astrocytes and prevent central nervous system damage,evidence suggests that activating this pathway could also yield beneficial outcomes.This dual function of the PI3K/AKT pathway underscores its complexity in astrocyte reactivity and brain function modulation.The review emphasizes the importance of employing astrocyte-exclusive models to understand their functions accurately and these models are essential for clarifying astrocyte behavior.The findings should then be validated using in vivo models to ensure real-life relevance.The review also highlights the significance of PI3K/AKT pathway modulation in preventing central nervous system damage,although further studies are required to fully comprehend its role due to varying factors such as different cell types,astrocyte responses to inflammation,and disease contexts.Specific strategies are clearly necessary to address these variables effectively.展开更多
Fracture(fault)reactivation can lead to dynamic geological hazards including earthquakes,rock collapses,landslides,and rock bursts.True triaxial compression tests were conducted to analyze the fracture reactivation pr...Fracture(fault)reactivation can lead to dynamic geological hazards including earthquakes,rock collapses,landslides,and rock bursts.True triaxial compression tests were conducted to analyze the fracture reactivation process under two different orientations of σ_(2),i.e.σ_(2) parallel to the fracture plane(Scheme 2)and σ_(2) cutting through the fracture plane(Scheme 3),under varying σ_(3) from 10 MPa to 40 MPa.The peak or fracture reactivation strength,deformation,failure mode,and post-peak mechanical behavior of intact(Scheme 1)and pre-fractured(Schemes 2 and 3)specimens were also compared.Results show that for intact specimens,the stress remains nearly constant in the residual sliding stage with no stick-slip,and the newly formed fracture surface only propagates along the σ_(2) direction when σ_(3) ranges from 10 MPa to 30 MPa,while it extends along both σ_(2) and σ_(3) directions when σ_(3) increases to 40 MPa;for the pre-fractured specimens,the fractures are usually reactivated under all the σ_(3) levels in Scheme 2,but fracture reactivation only occurs when σ_(3) is greater than 25 MPa in Scheme 3,below which new faulting traversing the original macro fracture occurs.In all the test schemes,both ε_(2) and ε_(3) experience an accumulative process of elongation,after which an abrupt change occurs at the point of the final failure;the degree of this change is dependent on the orientation of the new faulting or the slip direction of the original fracture,and it is generally more than 10 times larger in the slip direction of the original fracture than in the non-slip direction.Besides,the differential stress(peak stress)required for reactivation and the post-peak stress drop increase with increasing σ_(3).Post-peak stress drop and residual strength in Scheme 3 are generally greater than those in Scheme 2 at the same σ_(3) value.Our study clearly shows that intermediate principal stress orientation not only affects the fracture reactivation strength but also influences the slip deformation and failure modes.These new findings facilitate the mitigation of dynamic geological hazards associated with fracture and fault slip.展开更多
Excessive fluoride exposure is known to contribute to reproductive system dysfunction,ultimately leading to pathological damage and apoptosis in cells. Although both oxidative and endoplasmic reticulum（ER） stresses ...Excessive fluoride exposure is known to contribute to reproductive system dysfunction,ultimately leading to pathological damage and apoptosis in cells. Although both oxidative and endoplasmic reticulum（ER） stresses have been implicated in fluorosis, the signaling pathways and their roles in sodium fluoride（Na F）-induced apoptosis of Sertoli cells have been sparsely described. In this study, oxidative damage, ER stress, and apoptosis were analyzed after Sertoli cells were treated with varying doses of Na F for 24 hr. Moreover, the antioxidant N-acetylcysteine（NAC） and pro-apoptotic transcription factor CHOP knockdown were used to clarify the precise interplay between reactive oxygen species（ROS）, ER stress and their roles in NaF-induced apoptosis in Sertoli cells. The present study indicated that NaF significantly decreased cell viability and induced apoptosis in Sertoli cells. In addition, NaF exposure facilitated the accumulation of ROS and increased nuclear translocation of nuclear factor erythroid 2-related factor 2（Nrf2） in Sertoli cells. Treatment with NAC caused remarkable recovery from these NaF-induced responses. Meanwhile, excessive NaF triggered ER stress as evidenced by up-regulated glucose-regulated protein 78 k Da（GRP78）, PKR-like ER kinase（PERK）, phosphorylation of eukaryotic translation initiation factor 2α（p-eI F2α） and CCAAT/enhancer-binding protein-homologous protein（CHOP）, without affecting total eukaryotic translation initiation factor 2α（e IF2α）. NAC effectively blocked the activation of ER stress, suggesting that Na F-induced ROS is an early event that triggers ER stress. Taken together, the results demonstrate that the ROS-mediated ER stress pathway is the crucial mechanistic event involved in NaF-induced apoptosis of Sertoli cells.展开更多
As one of the most severe environmental stresses, freezing stress can determine native flora in nature and severely reduce crop production. Many mechanisms have been proposed to explain the damage induced by freezing-...As one of the most severe environmental stresses, freezing stress can determine native flora in nature and severely reduce crop production. Many mechanisms have been proposed to explain the damage induced by freezing-thawing cycle, and oxidative stress caused by uncontrollable production of harmful reactive oxygen species (ROS) are partially contributed to causing the injury. Plants in temperate regions have evolved a unique but effective metabolism of protecting themselves called cold acclimation. Cold-acclimating plants undergo a complex but orchestrated metabolic process to increase cold hardness triggered by exposure to low temperature and shortened photoperiod and achieve the maximum freezing tolerance by a concerted regulation and expression of a number of cold responsive genes. A complicated enzymatic system have been evolved in plants to scavenge the ROS to protect themselves from oxidative stress, therefore, cold-acclimating plants are expected to increase the de novo synthesis of the genes of antioxidant genes. Indeed, many antioxidant genes increase the expression levels in response to low temperature. Furthermore, the higher expression of many antioxidant enzymes are positively correlated to inducing higher tolerance levels against freezing. All the information summarized here can be applied for developing crop and horticultural plants to have more freezing tolerance for higher production with better quality. There have been extensive studies on the activities of antioxidant enzymes and the gene regulation, however, more researches will be required in near future to elucidate the most effective antioxidant enzymes to induce highest freezing tolerance in a crop plant in a transformation process or a breeding program.展开更多
Acute pancreatitis(AP)is a common acute gastrointestinal disorder affecting approximately 20%of patients with systemic inflammatory responses that may cause pancreatic and peripancreatic fat necrosis.This condition of...Acute pancreatitis(AP)is a common acute gastrointestinal disorder affecting approximately 20%of patients with systemic inflammatory responses that may cause pancreatic and peripancreatic fat necrosis.This condition often progresses to multiple organ failure,significantly increasing morbidity and mortality.Oxidative stress,characterized by an imbalance between the body’s reactive oxygen species(ROS)and antioxidants,activates the inflammatory signaling pathways.Although the pathogenesis of AP is not fully understood,ROS are increasingly recognized as critical in the disease's progression and development.Modulating the oxidative stress pathway has shown efficacy in mitigating the progression of AP.Despite numerous basic studies examining this pathway,comprehensive reviews of recent research remain sparse.This systematic review offers an in-depth examination of the critical role of oxidative stress in the pathogenesis and progression of AP and evaluates the therapeutic potential of antioxidant interventions in its management.展开更多
OBJECTIVE: To study the molecular mechanism of Buyang Huanwu Tang( 补阳还五汤)(BHT) protecting retinal ganglion cells(RGCs) from oxygen induced oxidative stress and apoptosis after anterior ischemia. METHODS: In this ...OBJECTIVE: To study the molecular mechanism of Buyang Huanwu Tang( 补阳还五汤)(BHT) protecting retinal ganglion cells(RGCs) from oxygen induced oxidative stress and apoptosis after anterior ischemia. METHODS: In this study, the Chinese herbs of BHT were extracted by first boiling in water, then were filtered, concentrated, and freeze-dried. The chemical profile of BHT extract was determined by liquid chromatography mass spectrometry(LC-MS). H2O2-induced RGC-5 cells were used as a cell model to investigate the protective effect and mechanism of BHT on RGCs. RESULTS: The survival rate of damaged RGC-5 by BHT was significantly increased by the 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazolium-romid method. Fluorescence activating cell sorter(FACS analysis) showed that BHT could significantly reduce apoptosis induced by oxidative stress via the reactive oxygen species(ROS)-mitogen-activated protein kinase(MAPK)-Caspase-3 signal pathway. CONCLUSION: BHT possesses a high antioxidant capacity and could significantly reduce ROS levels of RGC-5 cells damaged by H2O2.Therefore, the present study has provided possible alternative strategies for the prevention and treatment of ischemic optic disease by using traditional Chinese herbal formulas.展开更多
文摘Idiosyncratic hepatotoxicity accounts for many drug failures in the clinic and is a leading cause for black-boxed and withdrawn drugs. This toxicity has proven difficult to predict preclinically, but correlates with oxidative stress/reactive metabolites (OS/RM). As noted previously for antiepileptic compounds, many drugs causing idiosyncratic adverse drug effects are detected by OS/RM gene expression responses in the rat. In the present study, two immune activation models, low dose lipopolysaccharide (1 mg/kg IV) and 5% dextran sulphate sodium (DSS) in drinking water, were examined to determine if either would convert the non-toxic idiosyncratic toxicant carbamazepine (225 mg/kg) into a rat hepatotoxicant at 24 hours. Using the low dose LPS model, about 1/3 of the carbamazepine-treated rats either showed robust ALT and AST elevations with histopathological evidence of hepatotoxicity, or died. Rats in this LPS/carbamazepine group were subdivided based on ALT values into non-responders, responders or robust responders. Whereas most carbamazepine-induced mRNAs were repressed by LPS across all rats in this group, the OS/ RM genes aflatoxin aldehyde reductase (Afar) and glutathione transferase Ya (Gstya) were repressed only in the robust responder subgroup;it is unclear whether repression of these genes contributes to or results from hepatotoxicity. The OS/RM gene microsomal epoxide hydrolase (mEphx) showed repression across all rats. NAD(P)H: menadione oxidoreductase (Nmor) is an OS/RM-responsive gene that is also induced by LPS, confounding interpretation of its changes. After pretreatment with 5% DSS at 24 hours or for 5 days, using a protocol that reportedly produces increased endotoxin absorption, carbamazepine was not converted to a hepatototoxicant in any rats. Instead, DSS produced a pronounced (2- to 6-fold) and selective potentiation of carbamazepine induction of OS/RM-responsive mRNAs. The lack of repressive effects of DSS on these mRNAs or in converting carbamazepine to a hepatotoxicant was not due to desensitization of endotoxin responses since LPS was at least as effective when administered to DSS-pretreated rats. OS/RM gene repression may contribute to development of hepatotoxicity of carbamazepine in immune activation models.
基金the support received from the National Natural Science Foundation of China(Grant No.12302460)the State Key Laboratory of Explosion Science and Safety Protection(Grant No.YBKT24-02)。
文摘The reactive materials filled structure(RMFS)is a structural penetrator that replaces high explosive(HE)with reactive materials,presenting a novel self-distributed initiation,multiple deflagrations behavior during penetrating multi-layered plates,and generating a multipeak overpressure behind the plates.Here analytical models of RMFS self-distributed energy release and equivalent deflagration are developed.The multipeak overpressure formation model based on the single deflagration overpressure expression was promoted.The impact tests of RMFS on multi-layered plates at 584 m/s,616 m/s,and819 m/s were performed to validate the analytical model.Further,the influence of a single overpressure peak and time intervals versus impact velocity is discussed.The analysis results indicate that the deflagration happened within 20.68 mm behind the plate,the initial impact velocity and plate thickness are the crucial factors that dominate the self-distributed multipeak overpressure effect.Three formation patterns of multipeak overpressure are proposed.
基金financially supported by the National Natural Science Foundation of China(No.52573053).
文摘Reactive compatibilization has been widely applied to enhance the compatibility of polymer blends,thereby improving their mechanical properties.However,it generally reduces the chain mobility and regularity,often leading to slower polymer crystallization.Here,we demonstrate that reactive compatibilization in poly(lactic acid)/poly(butylene adipate-co-terephthalate)(PLA/PBAT)blends unexpectedly promotes PLA matrix crystallization during injection molding,in contrast to the retarded kinetics observed in differential scanning calorimetry isothermal crystallization studies.The phase morphology,rheological behavior,and crystalline structure were systematically analyzed to elucidate markedly different crystallization kinetics under static and shear fields.The potential mechanism underlying crystallization enhancement is attributed to PBAT domain refinement and viscosity increase induced by reactive compatibilization,which,under shear flow,create favorable conditions for crystallization by enhancing PBAT fibril nucleation and retarding the relaxation of oriented PLA chains.This study offers new perspectives on the effect of reactive compatibilization on the polymer crystallization behavior.
基金financially supported by the National Natural Science Foundation of China(Nos.52373070,52273071 and U25A20255)the Special Support Plan for High-Level Talents in Zhejiang Province(No.2022R51008)the HZNU scientific research and innovation team project(No.TD2025004).
文摘Rubber-toughened thermoplastic materials have become ubiquitous in modern society owing to their lightweight nature and desirable combination of advantageous performances.Despite the ever-increasing demand,the development of polymer alloys that are lightweight,high-strength,and high-toughness remains an ongoing challenge.Inspired by the unique“salami”microstructure from commercial acrylonitrile butadiene styrene copolymer(ABS)and high-impact polystyrene(HIPS),a facile approach was developed to overcome the trade-off between enhancing the toughness and rigidity of fully polymer-based alloys by virtue of elastomeric salami particles.This strategy entails pre-grafting rigid poly(lactic acid)(PLLA)chains with glycidyl methacrylate-grafted octene ethylene copolymer(POE-g-GMA)using complementary reactive groups.It can be envisaged that the PLLA grafts featuring strong incompatibility with polypropylene(PP)remain fixed in elastomer phase upon the subsequent melt compounding,facilitating the in situ formation of“hard core(PLLA)-soft shell(polyolefin elastomer,POE)”particles in polypropylene(PP)matrix.The all-polymer alloys containing elastomeric salami particles demonstrated unprecedented performance combinations,including upper notched impact strengths(56.8 kJ/m2),even higher tensile strength(36.8 MPa),and Young’s modulus(0.93 GPa)than that of the PP matrix.Furthermore,these materials are lightweight without the incorporation of reinforcing nano-fillers,which is competitive with industrial engineering plastics.It is highly anticipated that this universal and highly efficient protocol will be appropriate for arbitrary rubber toughened/reinforced systems,offering a paradigm in the design of advanced all-polymer alloys.
基金supported by the National Key R&D Program of China(No.2023YFC3707900)the National Natural Science Foundation of China(No.51978157).
文摘Biochar and zero-valent iron are promising materials for the removal of trichloroethylene(TCE)from groundwater,but further research is still required on the synergistic mechanism and hydraulic performance in the permeable reactive barriers(PRBs)with biochar-iron composites.In this work,biochar-iron composites were synthesized by two different methods,and subjected to the microscopic analysis,batch experiments and the PRB’s model tests.The results indicated that the removal rates of TCE on biochar-iron composites reached above 90%,and the optimal removal conditions were the initial pH of 6.0 and a biochar/iron mass ratio of 5:1.The removal of TCE on biochar-iron composites followed the pseudo-second-order and Freundlich models,and the maximum adsorption capacity of TCE was 25.95 mg/g.The adsorption of biochar and dechlorination of nZVI dominated the removal of TCE.Biochar significantly enhanced the dechlorination of TCE on nZVI through modifying the electrochemical characteristics to lower its corrosion potential of nZVI,promote direct electron transfer,and improve electronic transfer capability.M-5BC-1nZVI exhibited excellent hydraulic performance for maintaining an adequate permeability coefficient(10^(−6)to 10^(−5)m/s).
基金supported by the National Natural Science Foundation of China(22278021)State Key Laboratory of Chemical Engineering(No.SKL-ChE-23A01).
文摘Achieving high selectivity to 2,5-furandicarboxylic acid(FDCA)in the photocatalytic oxidation of 5-hydroxymethylfurfural(HMF)in aqueous solution advocates the principle of green and sustainable chemistry,but still remains a significant challenge.Herein,manipulating the reactive oxygen species(ROS)has been realized and dramatically promotes the selective photocatalytic oxidation of HMF in aqueous solution.A high FDCAyield of 98.6% has been achieved after 3 h of visible light irradiation over the as-prepared FeO_(x)-Au/TiO_(2) catalyst,being one of the leading photocatalytic performances.Furthermore,satisfactory FDCA yields of higher than 80%could be realized even in the outdoor environment under natural sunlight irradiation,regardless of sunny or cloudy weather.A combination study including physical characterization,kinetic analysis,radical trapping experiments and density functional theory calculations unveils the rate-determining step(oxidation of hydroxyl group)and respective contributions of the generated ROS(1O_(2) and·O_(2)-)in each step of the entire reaction network.The present work would push ahead the understanding of HMF photocatalytic oxidation and contribute to the rational design of high-performance photocatalysts.
文摘We are sorry for the mistakes of Affiliation,"a State Key Laboratory of Advanced Fiber Materials,Center for Advanced Low-Dimension Materials,Donghua University,Shanghai 201620,China"should be replaced by"a State Key Laboratory of Advanced Fiber Materials,Center for Advanced Low-Dimension Materials,College of Materials Science and Engineering,Donghua University,Shanghai 201620,China".We apologized for the inconvenience caused by this error.
文摘In real industrial microgrids(MGs),the length of the primary delivery feeder to the connection point of the main substation is sometimes long.This reduces the power factor and increases reactive power absorption along the primary delivery feeder from the external network.Besides,the giant induction electro-motors as the working horse of industries requires remarkable amounts of reactive power for electro-mechanical energy conversions.To reduce power losses and operating costs of the MG as well as to improve the voltage quality,this study aims at providing an insightful model for optimal placement and sizing of reactive power compensation capacitors in an industrial MG.In the presented model,the objective function considers voltage profile and network power factor improvement at the MG connection point.Also,it realizes power flow equations within which all operational security constraints are considered.Various reactive power compensation strategies including distributed group compensation,centralized compensation at the main substation,and distributed compensation along the primary delivery feeder are scrutinized.A real industrial MG,say as Urmia Petrochemical plant,is considered in numerical validations.The obtained results in each scenario are discussed in depth.As seen,the best performance is obtained when the optimal location and sizing of capacitors are simultaneously determined at the main buses of the industrial plants,at the main substation of the MG,and alongside the primary delivery feeder.In this way,74.81%improvement in power losses reduction,1.3%lower active power import from the main grid,23.5%improvement in power factor,and 37.5%improvement in network voltage deviation summation are seen in this case compared to the base case.
基金supported by Graduate Innovation Project of Shanxi Normal University(Grant No.2021Y443).
文摘Enhanced UV-B radiation represents a major environmental factor impacting global cereal production.Researchers have explored various approaches to reduce the detrimental impact of UV-B radiation on crops.Recently,engineered nanoparticles,particularly cerium oxide nanoparticles(CeO_(2)-NPs),have attracted widespread interest for their ability to boost plant tolerance to a range of abiotic stresses.This study investigates how CeO_(2)-NPs application affects the morphology,physiology,biochemistry,and transcriptomics profiles of wheat seedling roots subjected to enhanced UV-B stress.The findings demonstrate that CeO_(2)-NPs notably promoted root length,fresh and dry weights,and root activity(p<0.05)under enhanced UV-B stress.CeO_(2)-NP treatment reduced the content of hydrogen peroxide<(H_(2)O_(2))and malondialdehyde(MDA)in wheat,alleviating oxidative damage in seedling roots and partially restoring the root phenotype.Under non-UV-B stress conditions,CeO_(2)-NP treatment triggered the difference of 237 transcripts in plants relative to the control group.Under enhanced UV-B stress,CeO_(2)-NP treatment exhibited differentially expressed genes(DEGs)linked to the antioxidant defense mechanism responsible for reactive oxygen species(ROS)scavenging,compared to the non-nanoparticle control.This suggests that ROS scavenging may be a key mechanism by which CeO_(2)-NPs enhance wheat resistance to enhanced UV-B radiation.This study elucidates a potential molecular mechanism through which CeO_(2)nanoparticles may enhance wheat tolerance to UV-B stress.
基金supported by Yunnan Power Grid Co.,Ltd.Science and Technology Project:Research and application of key technologies for graphical-based power grid accident reconstruction and simulation(YNKJXM20240333).
文摘An optimized volt-ampere reactive(VAR)control framework is proposed for transmission-level power systems to simultaneously mitigate voltage deviations and active-power losses through coordinated control of large-scale wind/solar farms with shunt static var generators(SVGs).The model explicitly represents reactive-power regulation characteristics of doubly-fed wind turbines and PV inverters under real-time meteorological conditions,and quantifies SVG high-speed compensation capability,enabling seamless transition from localized VAR management to a globally coordinated strategy.An enhanced adaptive gain-sharing knowledge optimizer(AGSK-SD)integrates simulated annealing and diversity maintenance to autonomously tune voltage-control actions,renewable source reactive-power set-points,and SVG output.The algorithm adaptively modulates knowledge factors and ratios across search phases,performs SA-based fine-grained local exploitation,and periodically re-injects population diversity to prevent premature convergence.Comprehensive tests on IEEE 9-bus and 39-bus systems demonstrate AGSK-SD’s superiority over NSGA-II and MOPSO in hypervolume(HV),inverse generative distance(IGD),and spread metrics while maintaining acceptable computational burden.The method reduces network losses from 2.7191 to 2.15 MW(20.79%reduction)and from 15.1891 to 11.22 MW(26.16%reduction)in the 9-bus and 39-bus systems respectively.Simultaneously,the cumulative voltage-deviation index decreases from 0.0277 to 3.42×10^(−4) p.u.(98.77%reduction)in the 9-bus system,and from 0.0556 to 0.0107 p.u.(80.76%reduction)in the 39-bus system.These improvements demonstrate significant suppression of line losses and voltage fluctuations.Comparative analysis with traditional heuristic optimization algorithms confirms the superior performance of the proposed approach.
文摘Background:Theworld is nowexperiencing many crises and adversities of great impact that pose serious threats to both physical and mental health.Threats to mental health include major depressive disorder,which can be severe and disabling.The current study aimed to identify the prevalence of one type of depressive disorder,reactive depression(RD),and its relationship to demographic and psychological variables.Methods:For this study,RD is defined as an abnormal emotional response to traumatic situations involving mood difficulties.This study created an online self-report reactive depression questionnaire consisting of 23 items distributed across three subscales:1)bad feelings and life attitudes,2)loss of hope and loneliness,and 3)feeling sad and loss of confidence.The questionnaire was administered to a volunteer sample of 362male and female Iraqi university students.Exploratory Factor Analysis(EFA),Confirmatory Factor Analysis(CFA),t-tests,and one-way Analysis of Variance(ANOVA)were used to investigate exploratory and confirmatory factor structures of the questionnaire.Results:Evidence of reactive depression was found in 18.2%of the students.Female students had significantly higher levels of reactive depression than males(female N=205,mean=85.00,SD=11.30;male N=157,mean=76.46,SD=11.51).The high levels of reactive depression identified in these students demonstrate the value of assessing reactive depression in university students.Conclusion:The study underscores that the loss of emotional and psychological security,particularly in the face of traumatic and permanent events such as the death of a loved one,may contribute to the onset and progression of depressive symptoms.Future research should explore the role of specific cultural factors and further validate the reactive depression questionnaire in broader populations.Additionally,there is a need for improvedmental health support in Iraqi universities,particularly for female students,who may face unique challenges.
文摘Effects of sodium nitroprusside (SNP), a nitric oxide (NO) donor, on the germination and metabolism of reactive oxygen species were surveyed in wheat (Triticum aestivum L.) seeds. Germination of wheat seeds and even the elongation of radicle and plumule were dramatically promoted by SNP treatments during the germination under osmotic stress. Meanwhile, activities of amylase and EP were enhanced, thus leading to the degradation of storage reserve in seeds. After osmotic stress was removed, higher viability of wheat seeds was also maintained. In addition, the activities of CAT, APX and the content of proline were increased by SNP treatment simultaneously, but activities of LOX were inhibited, and both of which were beneficial for improving the antioxidant capacity during the germination of wheat seeds under osmotic stress. It was also shown that the increase of the activity of amylase induced by SNP in embryoless half-seeds of wheat in the beginning period of germination (6 h) might be indirectly related to GA(3).
基金Supported by First Affiliated Hospital of Nanjing Medical University and the National Natural Science Foundation of China,Grant No.81100270,No.81070380,No.81310108001,No.81210108017 and No.81273261
文摘AIM: To investigate the effects of N-acetylcysteine (NAC) on endoplasmic reticulum (ER) stress and tissue injury during liver ischemia reperfusion injury (IRI).
基金supported by the National 863 Program of China (2002AA2Z4011)the Foundation for Personnel of Henan University of Science and Technology China.
文摘Rice is one of the main staple food crops in the world, but it may suffer serious water stress during growth period. Water stress during grain filling results in decreased grain yeild, but its mechanism generating and scavenging the active oxygen is unclear under continuance of the water stress. The experiment was carried out in growth chamber to investigate the effects of water stress on the production of superoxide free radical （O2）, hydrogen peroxide （H202）, malondialdehyde （MDA）, reduced glutathione （GSH）, ascorbic acid （AsA）, and antioxidative enzyme activities in three rice hybrids with differing drought resistant under both normal and drought conditions during grain-filling stage. The results showed that water stress aggravated the membrane lipid peroxidation in rice leaves, which was more severe in less drought resistant hybrids than that in more tolerant ones. Also O2＇ and H2O2 accumulated more rapidly in less drought resistant hybrids than that in more tolerant ones. During water stress, decreases of GSH, AsA, chlorophyll, and relative water contents in more drought resistant hybrids were obvious less than those in less tolerant ones. Activities of superoxide dismutase （SOD）, catalase （CAT） and peroxidase （POD） in/eaves increased obviously in 0-14 d after heading and subsequently decreased rapidly, and those in more drought resistant hybrids were more than those in less tolerant ones. The results showed that changes of O2, H2O2, MDA, GSH, and AsA contents and antioxidative enzyme activities correlated significantly to drought resistance of rice hybrids, and more drought resistant hybrids possessed high ant oxidation capacity.
基金supported by Fondo Nacional de Desarrollo Científico y Tecnológico(FONDECYT)#1200836,#1210644,and#1240888,and Agencia Nacional de Investigación y Desarrollo(ANID)-FONDAP#15130011(to LL)FONDECYT#3230227(to MFG).
文摘Astrocytes are the most abundant type of glial cell in the central nervous system.Upon injury and inflammation,astrocytes become reactive and undergo morphological and functional changes.Depending on their phenotypic classification as A1 or A2,reactive astrocytes contribute to both neurotoxic and neuroprotective responses,respectively.However,this binary classification does not fully capture the diversity of astrocyte responses observed across different diseases and injuries.Transcriptomic analysis has revealed that reactive astrocytes have a complex landscape of gene expression profiles,which emphasizes the heterogeneous nature of their reactivity.Astrocytes actively participate in regulating central nervous system inflammation by interacting with microglia and other cell types,releasing cytokines,and influencing the immune response.The phosphoinositide 3-kinase(PI3K)/protein kinase B(AKT)signaling pathway is a central player in astrocyte reactivity and impacts various aspects of astrocyte behavior,as evidenced by in silico,in vitro,and in vivo results.In astrocytes,inflammatory cues trigger a cascade of molecular events,where nuclear factor-κB serves as a central mediator of the pro-inflammatory responses.Here,we review the heterogeneity of reactive astrocytes and the molecular mechanisms underlying their activation.We highlight the involvement of various signaling pathways that regulate astrocyte reactivity,including the PI3K/AKT/mammalian target of rapamycin(mTOR),αvβ3 integrin/PI3K/AKT/connexin 43,and Notch/PI3K/AKT pathways.While targeting the inactivation of the PI3K/AKT cellular signaling pathway to control reactive astrocytes and prevent central nervous system damage,evidence suggests that activating this pathway could also yield beneficial outcomes.This dual function of the PI3K/AKT pathway underscores its complexity in astrocyte reactivity and brain function modulation.The review emphasizes the importance of employing astrocyte-exclusive models to understand their functions accurately and these models are essential for clarifying astrocyte behavior.The findings should then be validated using in vivo models to ensure real-life relevance.The review also highlights the significance of PI3K/AKT pathway modulation in preventing central nervous system damage,although further studies are required to fully comprehend its role due to varying factors such as different cell types,astrocyte responses to inflammation,and disease contexts.Specific strategies are clearly necessary to address these variables effectively.
基金funding support from the National Nature Science Foundation of China(Grant No.42272334)the National Key Research and Development Program of China(Grant No.2022YFE0137200)the Taishan Scholars Program(Grant No.2019RKB01083).
文摘Fracture(fault)reactivation can lead to dynamic geological hazards including earthquakes,rock collapses,landslides,and rock bursts.True triaxial compression tests were conducted to analyze the fracture reactivation process under two different orientations of σ_(2),i.e.σ_(2) parallel to the fracture plane(Scheme 2)and σ_(2) cutting through the fracture plane(Scheme 3),under varying σ_(3) from 10 MPa to 40 MPa.The peak or fracture reactivation strength,deformation,failure mode,and post-peak mechanical behavior of intact(Scheme 1)and pre-fractured(Schemes 2 and 3)specimens were also compared.Results show that for intact specimens,the stress remains nearly constant in the residual sliding stage with no stick-slip,and the newly formed fracture surface only propagates along the σ_(2) direction when σ_(3) ranges from 10 MPa to 30 MPa,while it extends along both σ_(2) and σ_(3) directions when σ_(3) increases to 40 MPa;for the pre-fractured specimens,the fractures are usually reactivated under all the σ_(3) levels in Scheme 2,but fracture reactivation only occurs when σ_(3) is greater than 25 MPa in Scheme 3,below which new faulting traversing the original macro fracture occurs.In all the test schemes,both ε_(2) and ε_(3) experience an accumulative process of elongation,after which an abrupt change occurs at the point of the final failure;the degree of this change is dependent on the orientation of the new faulting or the slip direction of the original fracture,and it is generally more than 10 times larger in the slip direction of the original fracture than in the non-slip direction.Besides,the differential stress(peak stress)required for reactivation and the post-peak stress drop increase with increasing σ_(3).Post-peak stress drop and residual strength in Scheme 3 are generally greater than those in Scheme 2 at the same σ_(3) value.Our study clearly shows that intermediate principal stress orientation not only affects the fracture reactivation strength but also influences the slip deformation and failure modes.These new findings facilitate the mitigation of dynamic geological hazards associated with fracture and fault slip.
基金supported by the Key Science and Technology Research Project of Henan province of China (No: 13A330735)
文摘Excessive fluoride exposure is known to contribute to reproductive system dysfunction,ultimately leading to pathological damage and apoptosis in cells. Although both oxidative and endoplasmic reticulum（ER） stresses have been implicated in fluorosis, the signaling pathways and their roles in sodium fluoride（Na F）-induced apoptosis of Sertoli cells have been sparsely described. In this study, oxidative damage, ER stress, and apoptosis were analyzed after Sertoli cells were treated with varying doses of Na F for 24 hr. Moreover, the antioxidant N-acetylcysteine（NAC） and pro-apoptotic transcription factor CHOP knockdown were used to clarify the precise interplay between reactive oxygen species（ROS）, ER stress and their roles in NaF-induced apoptosis in Sertoli cells. The present study indicated that NaF significantly decreased cell viability and induced apoptosis in Sertoli cells. In addition, NaF exposure facilitated the accumulation of ROS and increased nuclear translocation of nuclear factor erythroid 2-related factor 2（Nrf2） in Sertoli cells. Treatment with NAC caused remarkable recovery from these NaF-induced responses. Meanwhile, excessive NaF triggered ER stress as evidenced by up-regulated glucose-regulated protein 78 k Da（GRP78）, PKR-like ER kinase（PERK）, phosphorylation of eukaryotic translation initiation factor 2α（p-eI F2α） and CCAAT/enhancer-binding protein-homologous protein（CHOP）, without affecting total eukaryotic translation initiation factor 2α（e IF2α）. NAC effectively blocked the activation of ER stress, suggesting that Na F-induced ROS is an early event that triggers ER stress. Taken together, the results demonstrate that the ROS-mediated ER stress pathway is the crucial mechanistic event involved in NaF-induced apoptosis of Sertoli cells.
文摘As one of the most severe environmental stresses, freezing stress can determine native flora in nature and severely reduce crop production. Many mechanisms have been proposed to explain the damage induced by freezing-thawing cycle, and oxidative stress caused by uncontrollable production of harmful reactive oxygen species (ROS) are partially contributed to causing the injury. Plants in temperate regions have evolved a unique but effective metabolism of protecting themselves called cold acclimation. Cold-acclimating plants undergo a complex but orchestrated metabolic process to increase cold hardness triggered by exposure to low temperature and shortened photoperiod and achieve the maximum freezing tolerance by a concerted regulation and expression of a number of cold responsive genes. A complicated enzymatic system have been evolved in plants to scavenge the ROS to protect themselves from oxidative stress, therefore, cold-acclimating plants are expected to increase the de novo synthesis of the genes of antioxidant genes. Indeed, many antioxidant genes increase the expression levels in response to low temperature. Furthermore, the higher expression of many antioxidant enzymes are positively correlated to inducing higher tolerance levels against freezing. All the information summarized here can be applied for developing crop and horticultural plants to have more freezing tolerance for higher production with better quality. There have been extensive studies on the activities of antioxidant enzymes and the gene regulation, however, more researches will be required in near future to elucidate the most effective antioxidant enzymes to induce highest freezing tolerance in a crop plant in a transformation process or a breeding program.
基金Supported by the National Natural Science Foundation of China,No.8217030254.
文摘Acute pancreatitis(AP)is a common acute gastrointestinal disorder affecting approximately 20%of patients with systemic inflammatory responses that may cause pancreatic and peripancreatic fat necrosis.This condition often progresses to multiple organ failure,significantly increasing morbidity and mortality.Oxidative stress,characterized by an imbalance between the body’s reactive oxygen species(ROS)and antioxidants,activates the inflammatory signaling pathways.Although the pathogenesis of AP is not fully understood,ROS are increasingly recognized as critical in the disease's progression and development.Modulating the oxidative stress pathway has shown efficacy in mitigating the progression of AP.Despite numerous basic studies examining this pathway,comprehensive reviews of recent research remain sparse.This systematic review offers an in-depth examination of the critical role of oxidative stress in the pathogenesis and progression of AP and evaluates the therapeutic potential of antioxidant interventions in its management.
基金Supported by China Postdoctoral Science Foundation (Experimental Study on the Inhibitory Effect of Yiqi Tongluo Method on RGCs Apoptosis in AION Model Rats, No. 2017M621180)。
文摘OBJECTIVE: To study the molecular mechanism of Buyang Huanwu Tang( 补阳还五汤)(BHT) protecting retinal ganglion cells(RGCs) from oxygen induced oxidative stress and apoptosis after anterior ischemia. METHODS: In this study, the Chinese herbs of BHT were extracted by first boiling in water, then were filtered, concentrated, and freeze-dried. The chemical profile of BHT extract was determined by liquid chromatography mass spectrometry(LC-MS). H2O2-induced RGC-5 cells were used as a cell model to investigate the protective effect and mechanism of BHT on RGCs. RESULTS: The survival rate of damaged RGC-5 by BHT was significantly increased by the 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazolium-romid method. Fluorescence activating cell sorter(FACS analysis) showed that BHT could significantly reduce apoptosis induced by oxidative stress via the reactive oxygen species(ROS)-mitogen-activated protein kinase(MAPK)-Caspase-3 signal pathway. CONCLUSION: BHT possesses a high antioxidant capacity and could significantly reduce ROS levels of RGC-5 cells damaged by H2O2.Therefore, the present study has provided possible alternative strategies for the prevention and treatment of ischemic optic disease by using traditional Chinese herbal formulas.
