Objective:To investigate the hepatic and reproductive toxicity of dichlorvos and lead acetate on male Wistar rats.Methods:Fifteen adult male Wistar rats(170-190 g)were randomly divided into three groups,with 5 rats in...Objective:To investigate the hepatic and reproductive toxicity of dichlorvos and lead acetate on male Wistar rats.Methods:Fifteen adult male Wistar rats(170-190 g)were randomly divided into three groups,with 5 rats in each group.Group 1 received 0.5 mL distilled water orally and served as the control group,while groups 2 and 3 were orally treated with 2 mg/kg body weight(b.w.)dichlorvos and 10 mg/kg b.w.lead acetate,respectively,for 55 days.Epididymal sperm,serum follicle stimulating hormone(FSH),luteinizing hormone(LH),testosterone concentrations,testicular 17β-hydroxysteroid dehydrogenase activity(17β-HSD),androgen receptor expression,aspartate aminotransferase(AST),alanine aminotransferase(ALT),testicular oxidant and antioxidant enzymes were evaluated with standard methods.Results:Sperm count,motility,morphology,FSH,LH,testosterone levels,17β-HSD,androgen receptor expression,and catalase activity were significantly reduced in the dichlorvos and lead acetate treated groups as compared with the control group(P<0.05).The liver AST,ALT activities and malondialdehyde concentration were significantly increased in the dichlorvos and lead acetate treated groups as compared with the control group(P<0.05).Conclusions:The reproductive and hepatic toxicity activities of dichlorvos and lead acetate in male Wistar rats are similar.展开更多
Objective:To evaluate the effect of different doses of lead acetate(1/20,1/40 and 1/60 of LD_(50))on body weight gain,blood picture,plasma prolein profile and the function of liver,kidney and thyroid gland.Methods:Mal...Objective:To evaluate the effect of different doses of lead acetate(1/20,1/40 and 1/60 of LD_(50))on body weight gain,blood picture,plasma prolein profile and the function of liver,kidney and thyroid gland.Methods:Male albino rats were divided into four groups,the first group represented the health control animals,while the second,third and fourth groups were ingested orally with sub lethal doses of load acetate(1/20,1/40 and 1/60)of the oral LD_(50),respectively.One dose was ingested every two days during the experimental period(14 weeks)including the adaptation time.Blood was collected and used for all analysis.Results:The results showed that,the ingestion of Pb^(2+)induced significant stimulation in glutamic-pyruvic transaminase(ALT)and glutamic-oxalacetic transaminease(AST)activity.Also,total soluble protein and albumin contents of plasma were significantly decreased,while the content of globulin was changed by the Pb^(2+)treatments.The cholinesteiase activity was inhibited,but the activities of alkaline and acid phosphates and lactate dehydrogenase were stimulated,while plasma glucose level was elevated as a result of lead acetate intoxication.In case of blood picture,Pb^(2+)ingestion reduced the contents of hemoglobin and RBCs count of intoxicated rat's blood and the plasma levels of T3,T4 and blood WBCs count were decreased.Conclusions:It can be concluded that lead acetate has harmful effect on experimental male albino rats.Therefore,the present work advises people to prevent exposure to the lead compound to avoid injurious hazard risk.展开更多
Grape seed extracts (GSE) are very potent antioxidant and exhibit numerous interesting pharmacologic activities, including an antioxidant property, and has been suggested to be of use in treatment of several diseases....Grape seed extracts (GSE) are very potent antioxidant and exhibit numerous interesting pharmacologic activities, including an antioxidant property, and has been suggested to be of use in treatment of several diseases. The present study has been undertaken to investigate the protective and therapeutic effect of GSE against lead-induced neuro and hepatotoxicity in rat. Male albino rats were divided into six groups: the 1st group, rats were injected daily with saline vehicle and served as negative control, the 2nd group (positive control group), the rats were injected (i.p.) with subacute dose (100 mg/kg b·w/day) of lead acetate (LA). The 3rd group (protective group), the rats were injected (i.p.) with LA (100 mg/kg b·w/day) for 7 days after treatment with GSE (100 mg/kg b·w/day) for 3 weeks. The 4th, 5th and 6th groups (therapeutics groups), rats were injected (i.p.) with subacut dose (100 mg/kg b·w/day) of lead acetate for 7 days, then treated with GSE (100 mg/kg b·w/day) for one, two and three weeks, respectively. The level of norepinephrine (NE), dopamine (DA), serotonin (5-HT) and 5-hydroxyindol acetic acid (5-HIAA) were evaluated in brain regions (cerebellum, brainstem, striatum, cerebral cortex, hypothalamus and hippocampus). The result indicated that the administration of subacute dose of LA (100 mg/kg/day, i.p.) induce a significant decrease in NE, DA, 5-HT and 5-HIAA content in all tested brain regions. Also the obtained data showed significant increase in liver enzymes: serum glutamate oxaloacetate transaminase (GOT), serum glutamate pyruvate transaminase (GPT) and Lactate dehydrogenase (LDH) level in group 2 (positive control). There is an improvement in neurotransmitters content. Also the obtained data showed significant in- crease in liver enzymes of protective (G3) and therapeutics groups (G4, G5 and G6) which received GSE compared with animal group that received lead acetate (G2). This is may be the presence of proanthocyanidins and procyanidins which have antioxidant and free radical scavenging activities. The result suggests that grape seed extract may prevent lead-induced neurotoxicity and hepatotoxicity.展开更多
Objectives: The aim of this study was to verify mitigating effects of the antioxidants α tocopherol (Vitamin E) and ascorbic acid (Vitamin C) on lead induced renal toxicity in adult male Wistar rats. Methods: A total...Objectives: The aim of this study was to verify mitigating effects of the antioxidants α tocopherol (Vitamin E) and ascorbic acid (Vitamin C) on lead induced renal toxicity in adult male Wistar rats. Methods: A total of 36 mature male Wistar rats separated into 1 control group fed with rat feeds and water only and 3 study groups fed with 10 mg/ml of lead acetate, 10 mg/ml of lead acetate + 200 mg/2ml of vitamin C and 10 mg/ml of lead acetate + 100 mg/2ml of vitamin E respectively in addition to feds and water for 28 days were used. Blood samples were obtained for renal indices and the kidneys of all rats were harvested, weighed and prepared for histological examination. Result: The percentage weight gain was highest among control rats (20.70%), followed by lead + vitamin E group (18.42%), lead + vitamin C group (17.00%) and the least amongst the lead group (9.50%). The mean serum uric acid of 419.20 ± 35.80 μmol/L in the lead treatment group was significantly higher than 395.50 ± 15.35 μmol/L, 393.30 ± 14.16 μmol/L and 387.67 ± 14.56 μmol/L in the lead + vitamin C group, lead + vitamin E group and controls respectively. The extent and proportion of renal tissue damage was higher in the lead-treated group and the commonest renal abnormalities observed were tubular and interstitial damage seen in 90.00% of rats in the lead-treated group compared to 75.00% and 60.00% in the lead + vitamin C and the lead + vitamin E groups respectively while the control rats had a normal histological appearance. Conclusions: The sub-acute administration of lead acetate may have inhibitory effect on growth of animals, and adversely affect renal function and histology with uric acid as a more reliable marker of lead induced renal toxicity compared to urea and creatinine. The histologic parameters of tubulointerstitial abnormalities were also consistent with lead toxicity. Antioxidants were useful in reducing lead induced renal damage and growth inhibition with vitamin E producing a more potent effect compared to Vitamin C.展开更多
Objective: To investigate the antioxidant and anti-caspase 3 effect of chitosan-Pinus merkusii extract nanoparticle on lead acetate-induced toxicity in rat testis. Methods: Chitosan-Pinus merkusii nanoparticles were i...Objective: To investigate the antioxidant and anti-caspase 3 effect of chitosan-Pinus merkusii extract nanoparticle on lead acetate-induced toxicity in rat testis. Methods: Chitosan-Pinus merkusii nanoparticles were identified by dynamic light scattering and scanning electron microscope. The male rats were divided into control group (rats were given with distilled water);lead acetate group [rats were injected with lead acetate 20 mg/kg body weight (BW) i.p.], and the treatment group (rats were given the chitosan-Pinus merkusii nanoparticle 150 mg;300 mg;600 mg/kg BW orally and were injected with lead acetate 20 mg/kg BW). The testis tissues were collected to evaluate the malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPx), histological evaluations of testis damage, and the caspase 3 mRNA expression was measured by reverse transcription-polymerase chain reaction. Results: The dynamic light scattering showed that the size of chitosan-Pinus merkusii nanoparticle was (530.2±38.2) nm. The scanning electron microscope images of the chitosan-Pinus merkusii nanoparticles showed an irregular shape, and the morphology surface showed the rough surface. The treatment with lead acetate resulted in significantly increasing MDA level and caspase 3 mRNA expression, and significantly decreasing level of SOD and GPx when compared with control group. The treatment with the chitosan-Pinus merkusii nanoparticle 600 mg/kg BW but not 150 and 300 mg/kg BW significantly decreased the MDA levels, caspase 3 mRNA expression, and also increased level of SOD and GPx when compared with lead acetate group. The lead acetate induced loss of the normal structure of testicular cells and necrosis, whereas treatment with chitosan-Pinus merkusii nanoparticle inhibited testicular cell necrosis. Conclusions: It can be concluded that chitosan-Pinus merkusii nanoparticle protects rat testis from oxidative damage and apoptosis caused by lead acetate, through increasing antioxidant and inhibiting caspase 3 expression.展开更多
Objective:To prove the effect of administered orally lead acetate exposure on Bax expression and the apoptosis index of granulosa cells on antral follicle female albino rats Wistar strain (Rattus norvegicus).Methods:P...Objective:To prove the effect of administered orally lead acetate exposure on Bax expression and the apoptosis index of granulosa cells on antral follicle female albino rats Wistar strain (Rattus norvegicus).Methods:Post-test only control group, using female albino rats Wistar strain aged (10-12) wk (reproductive age) weighing (100-200) g. Twenty-four animal samples were classified into one control group and three groups exposed to lead acetate in doses of 30, 100, and 300 ppm, respectively. Lead acetate was administered orally through a feeding tube over 30 d. Bax expression of granulosa cells on antral follicle was checked using immunohistochemistry, and apoptosis index were examined using Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL).Results:Lead increases apoptosis index on doses of 300 ppm. The increase of the Bax expression granulosa cell on antral follicle was not statistically significant.Conclusion:The exposure of lead acetate administrated orally can increase apoptosis index of granulosa cell on antral follicle although it doesn't affect Bax expression.展开更多
BACKGROUND: Lead can cause structural changes in the hippocampus, followed by damage to learning and memory functions, but its specific mechanisms are not yet clear. OBJECTIVE: To observe long-term toxicity of high-do...BACKGROUND: Lead can cause structural changes in the hippocampus, followed by damage to learning and memory functions, but its specific mechanisms are not yet clear. OBJECTIVE: To observe long-term toxicity of high-dose lead in drinking water on hippocampal tissue in rats, and analyze the potential association of oxidative damage, cell apoptosis, and pathology. DESIGN, TIME AND SETTING: A randomized, controlled animal experiment was performed at the Center for Medical Experiment, Lanzhou General Hospital of Lanzhou Military Area Command of Chinese PLA from May 2007 to October 2008. MATERIALS: Rabbit anti Bcl-2, Bax, and inducible nitric oxide synthase (iNOS) polyclonal antibodies were purchased from Santa Cruz Biotechnology, USA. An streptavidin-peroxidase immunohistochemistry kit and concentrated DAB kit were purchased from Beijing Zhongshan Biotechnology Company Limited, China. Crystal violet was purchased from Sigma, USA. METHODS: A total of 72 Wistar rats, aged 3 months, were randomly divided into control, low-, middle-, and high-dose lead groups, with 18 rats per group. Animal models were established through free drinking water contaminated by Pb2+ for 1, 3, and 6 months, respectively. MAIN OUTCOME MEASURES: The general toxicity of lead was dynamically observed; the levels of Pb2+ in the blood and brain tissue homogenate were detected using atomic absorption method; pathological changes were observed using hematoxylin-eosin staining and tigroid body staining; the protein expression levels of Bcl-2, Bax, and iNOS were dynamically observed using streptavidin-peroxidase immunohistochemistry of the hippocampus. RESULTS: Lead exposure reduced autonomic activities, produced a slumped appearance, slow responses, and lusterless fur, especially in the high-dose group. The amount of ingestion and hydroposia showed a decreasing trend, especially in middle- and high-dose groups. Lead levels in whole blood and brain homogenate were higher than controls (P < 0.01). Lead caused degeneration of hippocampal neurons and pyknosis, with fewer tigroid bodies, especially in high-dose lead group. Bcl-2 expression decreased with increasing lead dose (P < 0.01), whereas lead dose-dependently increased Bax levels (P < 0.01) and iNOS levels (P < 0.05). CONCLUSION: High levels of Pb2+ may disrupt hippocampal structure by passing through the blood brain barrier. Oxidative damage and apoptosis may be a toxicity mechanism of Pb2+ on the hippocampus.展开更多
Lead(Pb) is one of the most common environmental toxicants,exposure to which can cause significant neurotoxicity and an associated decline in brain function.This study investigated the possible neuroprotective role of...Lead(Pb) is one of the most common environmental toxicants,exposure to which can cause significant neurotoxicity and an associated decline in brain function.This study investigated the possible neuroprotective role of Indigofera oblongifolia leaf methanolic extract(IOLME) against lead-induced neurotoxicity.Rats were intraperitoneally injected with lead acetate,with or without IOLME(intragastric administration for 5 days),and the neuroprotective effect of IOLME was assessed by measuring the lead concentration,redox status(lipid peroxidation,nitric oxide and glutathione),enzymatic antioxidant activities(superoxide dismutase,catalase,glutathione peroxidase and reductase),PCR assays of apoptosis markers(Bax and Bcl-2)and histopathology of the brain.The increases in the lipid peroxidation,nitric oxide,and apoptosis,the decreases in the glutathione level and the activity of antioxidant enzymes,and the altered histology of the brain induced by lead acetate were mitigated in the brain of rats pre-treated with IOLME.These findings indicate that IOLME has beneficial effects and it mitigates lead acetate-induced neurotoxicity via its antioxidant and anti-apoptotic activities.展开更多
After intraperitoneal injection of 20 mg/kg lead acetate,rats received 8 weeks of treadmill exercise (15-22 m/min,25-64 minutes) and/or treadmill exercise at 1.6 km/h until exhaustion.The markers related to neurotoxic...After intraperitoneal injection of 20 mg/kg lead acetate,rats received 8 weeks of treadmill exercise (15-22 m/min,25-64 minutes) and/or treadmill exercise at 1.6 km/h until exhaustion.The markers related to neurotoxicity were measured by enzyme-linked immunosorbent assay method.8 weeks of treadmill exercise significantly increased brain-derived neurotrophic factor level in the hippocampus (P=0.04) and plasma level of total antioxidant capacity of rats exposed to lead acetate (P < 0.001),and significantly decreased plasma level of malondialdehyde (P < 0.001).Acute exercise only decreased the hippocampal malondialdehyde level (P=0.09) and increased brain-derived neurotrophic factor level in the hippocampus (P=0.66).Acute exercise also enhanced the total antioxidant capacity in rats exposed to lead acetate,insignificantly (P=0.99).These findings suggest that chronic treadmill exercise can significantly decrease neurotoxicity and alleviate oxidative stress in rats exposed to lead acetate.However,acute endurance exercise was not associated with these beneficial effects.展开更多
Two selenium(Se)-containing peptides from Se-enriched rice,TSeMMM and SeMDPGQQ,possess neuroprotective potency against lead(Pb2+)-induced cytotoxicity.However,the crosstalk between mRNA and microRNAs(miRNA)involved in...Two selenium(Se)-containing peptides from Se-enriched rice,TSeMMM and SeMDPGQQ,possess neuroprotective potency against lead(Pb2+)-induced cytotoxicity.However,the crosstalk between mRNA and microRNAs(miRNA)involved in the neuroprotection mechanism remains to be elucidated.In this study,RNA-sequencing and miRNA-sequencing were used to independently identify differentially expressed mRNAs and small RNAs profiles in Pb^(2+)-treated primary fetal rat cortical neurons and then the correlated miRNA-mRNA target pairs were obtained.It was found that 34 mRNAs related to oxidative phosphorylation could be reversed by pretreatment of TSeMMM and SeMDPGQQ.The protective effect of TSeMMM and SeMDPGQQ was mediated by upregulation of miR-107-3p,which downregulates the ATPase H+transporting V0 subunit e1(Atp6v0e1)mRNA level.A zebrafish model was applied to verify the relevance between the targeted mRNA and miRNA by real-time quantitative PCR.The results indicated that miR-107-3p was a potential therapeutic target to achieve neuroprotection of Se-containing peptides via stimulation of Atp6v0e1.展开更多
Epicatechin(EC)was used in this study to antagonize the cognitive dysfunction caused by lead(Pb)exposure in mice.Eight-week-old male Kunming mice were treated with PbCl_(2)(20 mg/kg)and/or EC(50 mg/kg)by gavage admini...Epicatechin(EC)was used in this study to antagonize the cognitive dysfunction caused by lead(Pb)exposure in mice.Eight-week-old male Kunming mice were treated with PbCl_(2)(20 mg/kg)and/or EC(50 mg/kg)by gavage administration for 4 weeks.Morris water maze test showed that EC could improve memory dysfunction induced by Pb.EC antagonized Ca^(2+)overload,activated Nrf2 signaling pathway and reduced the accumulation of Pb in the brain and serum,which suggested that EC might alter Pb distribution in mice.In vitro,spectroscopic analysis,potentiometric titration and docking studies were applied to inquiry into the interaction between bovine serum albumin(BSA)and Pb^(2+)in presence or absence of EC.EC was proved to chelate Pb^(2+)and reduced the interaction between BSA and Pb^(2+).In summary,EC might protect Pb-induced cognitive impairment by activating Nrf2 signaling pathway,and suppressing Pb accumulation via interference on the binding of Pb to albumin.展开更多
Lead iodide(PbI2) is a vital raw material for preparing perovskite solar cells(PSCs),and it not only takes part in forming the light absorption layer but also remains in the grain boundary as a passivator.In other wor...Lead iodide(PbI2) is a vital raw material for preparing perovskite solar cells(PSCs),and it not only takes part in forming the light absorption layer but also remains in the grain boundary as a passivator.In other words,the PbI2 content in the precursor and as formed film will affect the efficiency and stability of the PSCs.With moderate residual PbI2,it passivates the bulk/surface defects of perovskite,reduces the interfacial recombination,promotes the perovskite stability,minimizes the device hysteresis,and so on.Deficient PbI2 residue will reduce the interfacial passivation effect and device performance.In addition to facilitating the non-radiative recombination,over PbI2 residue can also lead to electronic insulation in the grain boundary and deteriorate the device performance.However,the impact and regulation of PbI2 residue on the device performance and stability is still not fully understood.Herein,a comprehensive and detailed review is presented by discussing the PbI2 residue impact and its regulation strategies(i.e., elimination,facilitation and conversion of the residue PbI2) to manipulate the PbI2 content,distribution and forms.Finally,we also show future outlooks in this field,with an aim to help further the progression of high-efficiency and stable PSCs.展开更多
Objective:To evaluate the effect of the ethyl acetate fraction derived from Sargassum pallidum extract against particulate matter(PM)-induced oxidative stress and inflammation in HaCaT cells and zebrafish.Methods:HaCa...Objective:To evaluate the effect of the ethyl acetate fraction derived from Sargassum pallidum extract against particulate matter(PM)-induced oxidative stress and inflammation in HaCaT cells and zebrafish.Methods:HaCaT cells and zebrafish were used to evaluate the protective effects of the ethyl acetate fraction of Sargassum pallidum extract against PM-induced oxidative stress and inflammation.The production of nitric oxide(NO),intracellular ROS,prostaglandin E2(PGE2),and pro-inflammatory cytokines,and the expression levels of COX-2,iNOS,and NF-κB were evaluated in PM-induced HaCaT cells.Furthermore,the levels of ROS,NO,and lipid peroxidation were assessed in the PM-exposed zebrafish model.Results:The ethyl acetate fraction of Sargassum pallidum extract significantly decreased the production of NO,intracellular ROS,and PGE2 in PM-induced HaCaT cells.In addition,the fraction markedly suppressed the levels of pro-inflammatory cytokines and inhibited the expression levels of COX-2,iNOS,and NF-κB.Furthermore,it displayed remarkable protective effects against PM-induced inflammatory response and oxidative stress,represented by the reduction of NO,ROS,and lipid peroxidation in zebrafish.Conclusions:The ethyl acetate fraction of Sargassum pallidum extract exhibits a protective effect against PM-induced oxidative stress and inflammation both in vitro and in vivo and has the potential as a candidate for the development of pharmaceutical and cosmeceutical products.展开更多
In this study,green zinc oxide(ZnO)/polypyrrole(Ppy)/cellulose acetate(CA)film has been synthesized via solvent casting.This film was used as supporting material for glucose oxidase(GOx)to sensitize a glucose biosenso...In this study,green zinc oxide(ZnO)/polypyrrole(Ppy)/cellulose acetate(CA)film has been synthesized via solvent casting.This film was used as supporting material for glucose oxidase(GOx)to sensitize a glucose biosensor.ZnO nanoparticles have been prepared via the green route using olive leaves extract as a reductant.ZnO/Ppy nanocomposite has been synthesized by a simple in-situ chemical oxidative polymerization of pyrrole(Py)monomer using ferric chloride(FeCl3)as an oxidizing agent.The produced materials and the composite films were characterized using X-ray diffraction analysis(XRD),scanning electron microscope(SEM),Fourier transform infrared(FTIR)and thermogravimetric analysis(TGA).Glucose oxidase was successfully immobilized on the surface of the prepared film and then ZnO/Ppy/CA/GOx composite was sputtered with platinum electrode for the current determination at different initial concentrations of glucose.Current measurements proved the suitability and the high sensitivity of the constructed biosensor for the detection of glucose levels in different samples.The performance of the prepared biosensor has been assessed by measuring and comparing glucose concentrations up to 800 ppm.The results affirmed the reliability of the developed biosensor towards real samples which suggests the wide-scale application of the proposed biosensor.展开更多
Forecasting uncertainties among meteorological fields have long been recognized as the main limitation on the accuracy and predictability of air quality forecasts.However,the particular impact of meteorological foreca...Forecasting uncertainties among meteorological fields have long been recognized as the main limitation on the accuracy and predictability of air quality forecasts.However,the particular impact of meteorological forecasting uncertainties on air quality forecasts specific to different seasons is still not well known.In this study,a series of forecasts with different forecast lead times for January,April,July,and October of 2018 are conducted over the Beijing-Tianjin-Hebei(BTH)region and the impacts of meteorological forecasting uncertainties on surface PM_(2.5)concentration forecasts with each lead time are investigated.With increased lead time,the forecasted PM_(2.5)concentrations significantly change and demonstrate obvious seasonal variations.In general,the forecasting uncertainties in monthly mean surface PM_(2.5)concentrations in the BTH region due to lead time are the largest(80%)in spring,followed by autumn(~50%),summer(~40%),and winter(20%).In winter,the forecasting uncertainties in total surface PM_(2.5)mass due to lead time are mainly due to the uncertainties in PBL heights and hence the PBL mixing of anthropogenic primary particles.In spring,the forecasting uncertainties are mainly from the impacts of lead time on lower-tropospheric northwesterly winds,thereby further enhancing the condensation production of anthropogenic secondary particles by the long-range transport of natural dust.In summer,the forecasting uncertainties result mainly from the decrease in dry and wet deposition rates,which are associated with the reduction of near-surface wind speed and precipitation rate.In autumn,the forecasting uncertainties arise mainly from the change in the transport of remote natural dust and anthropogenic particles,which is associated with changes in the large-scale circulation.展开更多
Drought events have become more frequent and intense over East Asia in recent decades,leading to huge socioeconomic impacts.Although the droughts have been studied extensively by cases or for individual regions,their ...Drought events have become more frequent and intense over East Asia in recent decades,leading to huge socioeconomic impacts.Although the droughts have been studied extensively by cases or for individual regions,their leading variability and associated causes remain unclear.Based on the Standardized Precipitation Evapotranspiration Index(SPEI)and ERA5 reanalysis product from 1979 to 2020,this study evealuates the severity of spring droughts in East Asia and investigates their variations and associated drivers.The results indicate that North China and Mongolia have experienced remarkable trends toward dryness during spring in recent decades,while southwestern China has witnessed an opposite trend toward wetness.The first Empirical Orthogonal Function mode of SPEI variability reveals a similar seesawing pattern,with more severe dryness in northwestern China,Mongolia,North China,South Korea,and Japan but increased wetness in Southwestern China and southeast Asia.Further investigation reveals that the anomalously dry(wet)surface in North(Southwestern)China is significantly associated with anomalously high(low)temperature,less(more)precipitation,and reduced(increased)soil moisture during the previous winter and early spring,regulated by an anomalous anticyclone(cyclone)and thus reduced(increased)water vapor convergence.The spring dry-wet pattern in East Asia is also linked to cold sea surface temperature anomalies in the central-eastern Pacific.The findings of this study have important implications for improving the prediction of spring drought events in East Asia.展开更多
The goal is to develop a hybrid IPN network of polyvinyl acetate (PVAc) and ethylene-vinyl acetate (VAE). In this research work, the vinyl acetate (VAc)/ VAE hybrid emulsion and polyvinyl acetate emulsion (PVAc) were ...The goal is to develop a hybrid IPN network of polyvinyl acetate (PVAc) and ethylene-vinyl acetate (VAE). In this research work, the vinyl acetate (VAc)/ VAE hybrid emulsion and polyvinyl acetate emulsion (PVAc) were effectively synthesized. Emulsions with various characteristics have been developed by adjusting the weight ratios between the vinyl acetate monomer and the VAE component. The impacts on the mechanical, thermal, and physical properties of the films were investigated using tests for pencil hardness, tensile shear strength, pH, contact angle measurement, differential scanning calorimetry (DSC), and viscosity. When 5.0 weight percent VAE was added, the tensile shear strength in dry conditions decreased by 18.75% after a 24-hour bonding period, the heat resistance decreased by 26.29% (as per WATT 91) and the tensile shear strength decreased by approximately 36.52% in wet conditions (per EN 204). The pristine sample’s results were also confirmed by the contact angle test. The interpenetrating network (IPN) formation in hybrid PVAc emulsion as primary bonds does not directly attach to PVAc and VAE chains. The addition of VAE reduced the mechanical properties (at dry conditions) and heat resistance as per WATT 91. Contact angle analysis demonstrated that PVAc adhesives containing VAE had increased water resistance when compared to conventional PVA stabilised PVAc homopolymer-based adhesives. When compared to virgin PVAc Homo, the water resistance of the PVAc emulsion polymerization was enhanced by the addition of VAE.展开更多
Lead(Pb) and furan are toxic agents, and persistent exposure may impair human and animal reproductive function. We therefore explored the effects of Pb and furan on male rat hypothalamic-pituitary-gonadal reproductive...Lead(Pb) and furan are toxic agents, and persistent exposure may impair human and animal reproductive function. We therefore explored the effects of Pb and furan on male rat hypothalamic-pituitary-gonadal reproductive status, oxidative stress, inflammation, and genomic integrity. We found that co-exposure to Pb and furan reduced the activities of testicular function enzymes, endogenous antioxidant levels, total sulfhydryl group,and glutathione. Sperm abnormality, biomarkers of oxidative stress, inflammation, and p53 expression were increased in a dose-dependent manner by treatment with furan and Pb. Typical rat gonad histoarchitecture features were also damaged. Conclusively, co-exposure to Pb and furan induced male reproductive function derangement by decreasing the antioxidant defences in rats, increasing abnormalities in spermatozoa morphology, and reducing reproductive hormone in circulation. These pathophysiological alterations, if persistent, might provide a permissive environment for potentiating reproductive dysfunction and infertility.展开更多
文摘Objective:To investigate the hepatic and reproductive toxicity of dichlorvos and lead acetate on male Wistar rats.Methods:Fifteen adult male Wistar rats(170-190 g)were randomly divided into three groups,with 5 rats in each group.Group 1 received 0.5 mL distilled water orally and served as the control group,while groups 2 and 3 were orally treated with 2 mg/kg body weight(b.w.)dichlorvos and 10 mg/kg b.w.lead acetate,respectively,for 55 days.Epididymal sperm,serum follicle stimulating hormone(FSH),luteinizing hormone(LH),testosterone concentrations,testicular 17β-hydroxysteroid dehydrogenase activity(17β-HSD),androgen receptor expression,aspartate aminotransferase(AST),alanine aminotransferase(ALT),testicular oxidant and antioxidant enzymes were evaluated with standard methods.Results:Sperm count,motility,morphology,FSH,LH,testosterone levels,17β-HSD,androgen receptor expression,and catalase activity were significantly reduced in the dichlorvos and lead acetate treated groups as compared with the control group(P<0.05).The liver AST,ALT activities and malondialdehyde concentration were significantly increased in the dichlorvos and lead acetate treated groups as compared with the control group(P<0.05).Conclusions:The reproductive and hepatic toxicity activities of dichlorvos and lead acetate in male Wistar rats are similar.
基金Supported by Management of Agriculture,Cario University
文摘Objective:To evaluate the effect of different doses of lead acetate(1/20,1/40 and 1/60 of LD_(50))on body weight gain,blood picture,plasma prolein profile and the function of liver,kidney and thyroid gland.Methods:Male albino rats were divided into four groups,the first group represented the health control animals,while the second,third and fourth groups were ingested orally with sub lethal doses of load acetate(1/20,1/40 and 1/60)of the oral LD_(50),respectively.One dose was ingested every two days during the experimental period(14 weeks)including the adaptation time.Blood was collected and used for all analysis.Results:The results showed that,the ingestion of Pb^(2+)induced significant stimulation in glutamic-pyruvic transaminase(ALT)and glutamic-oxalacetic transaminease(AST)activity.Also,total soluble protein and albumin contents of plasma were significantly decreased,while the content of globulin was changed by the Pb^(2+)treatments.The cholinesteiase activity was inhibited,but the activities of alkaline and acid phosphates and lactate dehydrogenase were stimulated,while plasma glucose level was elevated as a result of lead acetate intoxication.In case of blood picture,Pb^(2+)ingestion reduced the contents of hemoglobin and RBCs count of intoxicated rat's blood and the plasma levels of T3,T4 and blood WBCs count were decreased.Conclusions:It can be concluded that lead acetate has harmful effect on experimental male albino rats.Therefore,the present work advises people to prevent exposure to the lead compound to avoid injurious hazard risk.
文摘Grape seed extracts (GSE) are very potent antioxidant and exhibit numerous interesting pharmacologic activities, including an antioxidant property, and has been suggested to be of use in treatment of several diseases. The present study has been undertaken to investigate the protective and therapeutic effect of GSE against lead-induced neuro and hepatotoxicity in rat. Male albino rats were divided into six groups: the 1st group, rats were injected daily with saline vehicle and served as negative control, the 2nd group (positive control group), the rats were injected (i.p.) with subacute dose (100 mg/kg b·w/day) of lead acetate (LA). The 3rd group (protective group), the rats were injected (i.p.) with LA (100 mg/kg b·w/day) for 7 days after treatment with GSE (100 mg/kg b·w/day) for 3 weeks. The 4th, 5th and 6th groups (therapeutics groups), rats were injected (i.p.) with subacut dose (100 mg/kg b·w/day) of lead acetate for 7 days, then treated with GSE (100 mg/kg b·w/day) for one, two and three weeks, respectively. The level of norepinephrine (NE), dopamine (DA), serotonin (5-HT) and 5-hydroxyindol acetic acid (5-HIAA) were evaluated in brain regions (cerebellum, brainstem, striatum, cerebral cortex, hypothalamus and hippocampus). The result indicated that the administration of subacute dose of LA (100 mg/kg/day, i.p.) induce a significant decrease in NE, DA, 5-HT and 5-HIAA content in all tested brain regions. Also the obtained data showed significant increase in liver enzymes: serum glutamate oxaloacetate transaminase (GOT), serum glutamate pyruvate transaminase (GPT) and Lactate dehydrogenase (LDH) level in group 2 (positive control). There is an improvement in neurotransmitters content. Also the obtained data showed significant in- crease in liver enzymes of protective (G3) and therapeutics groups (G4, G5 and G6) which received GSE compared with animal group that received lead acetate (G2). This is may be the presence of proanthocyanidins and procyanidins which have antioxidant and free radical scavenging activities. The result suggests that grape seed extract may prevent lead-induced neurotoxicity and hepatotoxicity.
文摘Objectives: The aim of this study was to verify mitigating effects of the antioxidants α tocopherol (Vitamin E) and ascorbic acid (Vitamin C) on lead induced renal toxicity in adult male Wistar rats. Methods: A total of 36 mature male Wistar rats separated into 1 control group fed with rat feeds and water only and 3 study groups fed with 10 mg/ml of lead acetate, 10 mg/ml of lead acetate + 200 mg/2ml of vitamin C and 10 mg/ml of lead acetate + 100 mg/2ml of vitamin E respectively in addition to feds and water for 28 days were used. Blood samples were obtained for renal indices and the kidneys of all rats were harvested, weighed and prepared for histological examination. Result: The percentage weight gain was highest among control rats (20.70%), followed by lead + vitamin E group (18.42%), lead + vitamin C group (17.00%) and the least amongst the lead group (9.50%). The mean serum uric acid of 419.20 ± 35.80 μmol/L in the lead treatment group was significantly higher than 395.50 ± 15.35 μmol/L, 393.30 ± 14.16 μmol/L and 387.67 ± 14.56 μmol/L in the lead + vitamin C group, lead + vitamin E group and controls respectively. The extent and proportion of renal tissue damage was higher in the lead-treated group and the commonest renal abnormalities observed were tubular and interstitial damage seen in 90.00% of rats in the lead-treated group compared to 75.00% and 60.00% in the lead + vitamin C and the lead + vitamin E groups respectively while the control rats had a normal histological appearance. Conclusions: The sub-acute administration of lead acetate may have inhibitory effect on growth of animals, and adversely affect renal function and histology with uric acid as a more reliable marker of lead induced renal toxicity compared to urea and creatinine. The histologic parameters of tubulointerstitial abnormalities were also consistent with lead toxicity. Antioxidants were useful in reducing lead induced renal damage and growth inhibition with vitamin E producing a more potent effect compared to Vitamin C.
文摘Objective: To investigate the antioxidant and anti-caspase 3 effect of chitosan-Pinus merkusii extract nanoparticle on lead acetate-induced toxicity in rat testis. Methods: Chitosan-Pinus merkusii nanoparticles were identified by dynamic light scattering and scanning electron microscope. The male rats were divided into control group (rats were given with distilled water);lead acetate group [rats were injected with lead acetate 20 mg/kg body weight (BW) i.p.], and the treatment group (rats were given the chitosan-Pinus merkusii nanoparticle 150 mg;300 mg;600 mg/kg BW orally and were injected with lead acetate 20 mg/kg BW). The testis tissues were collected to evaluate the malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GPx), histological evaluations of testis damage, and the caspase 3 mRNA expression was measured by reverse transcription-polymerase chain reaction. Results: The dynamic light scattering showed that the size of chitosan-Pinus merkusii nanoparticle was (530.2±38.2) nm. The scanning electron microscope images of the chitosan-Pinus merkusii nanoparticles showed an irregular shape, and the morphology surface showed the rough surface. The treatment with lead acetate resulted in significantly increasing MDA level and caspase 3 mRNA expression, and significantly decreasing level of SOD and GPx when compared with control group. The treatment with the chitosan-Pinus merkusii nanoparticle 600 mg/kg BW but not 150 and 300 mg/kg BW significantly decreased the MDA levels, caspase 3 mRNA expression, and also increased level of SOD and GPx when compared with lead acetate group. The lead acetate induced loss of the normal structure of testicular cells and necrosis, whereas treatment with chitosan-Pinus merkusii nanoparticle inhibited testicular cell necrosis. Conclusions: It can be concluded that chitosan-Pinus merkusii nanoparticle protects rat testis from oxidative damage and apoptosis caused by lead acetate, through increasing antioxidant and inhibiting caspase 3 expression.
文摘Objective:To prove the effect of administered orally lead acetate exposure on Bax expression and the apoptosis index of granulosa cells on antral follicle female albino rats Wistar strain (Rattus norvegicus).Methods:Post-test only control group, using female albino rats Wistar strain aged (10-12) wk (reproductive age) weighing (100-200) g. Twenty-four animal samples were classified into one control group and three groups exposed to lead acetate in doses of 30, 100, and 300 ppm, respectively. Lead acetate was administered orally through a feeding tube over 30 d. Bax expression of granulosa cells on antral follicle was checked using immunohistochemistry, and apoptosis index were examined using Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL).Results:Lead increases apoptosis index on doses of 300 ppm. The increase of the Bax expression granulosa cell on antral follicle was not statistically significant.Conclusion:The exposure of lead acetate administrated orally can increase apoptosis index of granulosa cell on antral follicle although it doesn't affect Bax expression.
基金a Research Grant for Science From Gansu Provincial Science & Technology Department, No. 090NKCA106
文摘BACKGROUND: Lead can cause structural changes in the hippocampus, followed by damage to learning and memory functions, but its specific mechanisms are not yet clear. OBJECTIVE: To observe long-term toxicity of high-dose lead in drinking water on hippocampal tissue in rats, and analyze the potential association of oxidative damage, cell apoptosis, and pathology. DESIGN, TIME AND SETTING: A randomized, controlled animal experiment was performed at the Center for Medical Experiment, Lanzhou General Hospital of Lanzhou Military Area Command of Chinese PLA from May 2007 to October 2008. MATERIALS: Rabbit anti Bcl-2, Bax, and inducible nitric oxide synthase (iNOS) polyclonal antibodies were purchased from Santa Cruz Biotechnology, USA. An streptavidin-peroxidase immunohistochemistry kit and concentrated DAB kit were purchased from Beijing Zhongshan Biotechnology Company Limited, China. Crystal violet was purchased from Sigma, USA. METHODS: A total of 72 Wistar rats, aged 3 months, were randomly divided into control, low-, middle-, and high-dose lead groups, with 18 rats per group. Animal models were established through free drinking water contaminated by Pb2+ for 1, 3, and 6 months, respectively. MAIN OUTCOME MEASURES: The general toxicity of lead was dynamically observed; the levels of Pb2+ in the blood and brain tissue homogenate were detected using atomic absorption method; pathological changes were observed using hematoxylin-eosin staining and tigroid body staining; the protein expression levels of Bcl-2, Bax, and iNOS were dynamically observed using streptavidin-peroxidase immunohistochemistry of the hippocampus. RESULTS: Lead exposure reduced autonomic activities, produced a slumped appearance, slow responses, and lusterless fur, especially in the high-dose group. The amount of ingestion and hydroposia showed a decreasing trend, especially in middle- and high-dose groups. Lead levels in whole blood and brain homogenate were higher than controls (P < 0.01). Lead caused degeneration of hippocampal neurons and pyknosis, with fewer tigroid bodies, especially in high-dose lead group. Bcl-2 expression decreased with increasing lead dose (P < 0.01), whereas lead dose-dependently increased Bax levels (P < 0.01) and iNOS levels (P < 0.05). CONCLUSION: High levels of Pb2+ may disrupt hippocampal structure by passing through the blood brain barrier. Oxidative damage and apoptosis may be a toxicity mechanism of Pb2+ on the hippocampus.
基金the Deanship of Scientific Research at King Saud University for funding the work through the research group project,No.PRG-1436-02
文摘Lead(Pb) is one of the most common environmental toxicants,exposure to which can cause significant neurotoxicity and an associated decline in brain function.This study investigated the possible neuroprotective role of Indigofera oblongifolia leaf methanolic extract(IOLME) against lead-induced neurotoxicity.Rats were intraperitoneally injected with lead acetate,with or without IOLME(intragastric administration for 5 days),and the neuroprotective effect of IOLME was assessed by measuring the lead concentration,redox status(lipid peroxidation,nitric oxide and glutathione),enzymatic antioxidant activities(superoxide dismutase,catalase,glutathione peroxidase and reductase),PCR assays of apoptosis markers(Bax and Bcl-2)and histopathology of the brain.The increases in the lipid peroxidation,nitric oxide,and apoptosis,the decreases in the glutathione level and the activity of antioxidant enzymes,and the altered histology of the brain induced by lead acetate were mitigated in the brain of rats pre-treated with IOLME.These findings indicate that IOLME has beneficial effects and it mitigates lead acetate-induced neurotoxicity via its antioxidant and anti-apoptotic activities.
文摘After intraperitoneal injection of 20 mg/kg lead acetate,rats received 8 weeks of treadmill exercise (15-22 m/min,25-64 minutes) and/or treadmill exercise at 1.6 km/h until exhaustion.The markers related to neurotoxicity were measured by enzyme-linked immunosorbent assay method.8 weeks of treadmill exercise significantly increased brain-derived neurotrophic factor level in the hippocampus (P=0.04) and plasma level of total antioxidant capacity of rats exposed to lead acetate (P < 0.001),and significantly decreased plasma level of malondialdehyde (P < 0.001).Acute exercise only decreased the hippocampal malondialdehyde level (P=0.09) and increased brain-derived neurotrophic factor level in the hippocampus (P=0.66).Acute exercise also enhanced the total antioxidant capacity in rats exposed to lead acetate,insignificantly (P=0.99).These findings suggest that chronic treadmill exercise can significantly decrease neurotoxicity and alleviate oxidative stress in rats exposed to lead acetate.However,acute endurance exercise was not associated with these beneficial effects.
基金supported by the National Natural Science Foundation of China(32272319,31972020,32202032)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘Two selenium(Se)-containing peptides from Se-enriched rice,TSeMMM and SeMDPGQQ,possess neuroprotective potency against lead(Pb2+)-induced cytotoxicity.However,the crosstalk between mRNA and microRNAs(miRNA)involved in the neuroprotection mechanism remains to be elucidated.In this study,RNA-sequencing and miRNA-sequencing were used to independently identify differentially expressed mRNAs and small RNAs profiles in Pb^(2+)-treated primary fetal rat cortical neurons and then the correlated miRNA-mRNA target pairs were obtained.It was found that 34 mRNAs related to oxidative phosphorylation could be reversed by pretreatment of TSeMMM and SeMDPGQQ.The protective effect of TSeMMM and SeMDPGQQ was mediated by upregulation of miR-107-3p,which downregulates the ATPase H+transporting V0 subunit e1(Atp6v0e1)mRNA level.A zebrafish model was applied to verify the relevance between the targeted mRNA and miRNA by real-time quantitative PCR.The results indicated that miR-107-3p was a potential therapeutic target to achieve neuroprotection of Se-containing peptides via stimulation of Atp6v0e1.
基金supported by the National Key Research and Development Program of China under Grant(2022YFF1102800)the Graduate Scientific Research Innovation Project of Tianji(2022SKY109)+1 种基金the Project of Tianjin Science and Technology Program(22JCYBJC00360)the Project of Tianjin Science and Technology Program(21ZYJDJC00060)。
文摘Epicatechin(EC)was used in this study to antagonize the cognitive dysfunction caused by lead(Pb)exposure in mice.Eight-week-old male Kunming mice were treated with PbCl_(2)(20 mg/kg)and/or EC(50 mg/kg)by gavage administration for 4 weeks.Morris water maze test showed that EC could improve memory dysfunction induced by Pb.EC antagonized Ca^(2+)overload,activated Nrf2 signaling pathway and reduced the accumulation of Pb in the brain and serum,which suggested that EC might alter Pb distribution in mice.In vitro,spectroscopic analysis,potentiometric titration and docking studies were applied to inquiry into the interaction between bovine serum albumin(BSA)and Pb^(2+)in presence or absence of EC.EC was proved to chelate Pb^(2+)and reduced the interaction between BSA and Pb^(2+).In summary,EC might protect Pb-induced cognitive impairment by activating Nrf2 signaling pathway,and suppressing Pb accumulation via interference on the binding of Pb to albumin.
基金financially supported by the National Natural Science Foundation of China(U21A2078,22179042,and 12104170)the Natural Science Foundation of Fujian Province(2020J06021 and 2020J01064)Scientific Research Funds of Huaqiao University(23BS109)。
文摘Lead iodide(PbI2) is a vital raw material for preparing perovskite solar cells(PSCs),and it not only takes part in forming the light absorption layer but also remains in the grain boundary as a passivator.In other words,the PbI2 content in the precursor and as formed film will affect the efficiency and stability of the PSCs.With moderate residual PbI2,it passivates the bulk/surface defects of perovskite,reduces the interfacial recombination,promotes the perovskite stability,minimizes the device hysteresis,and so on.Deficient PbI2 residue will reduce the interfacial passivation effect and device performance.In addition to facilitating the non-radiative recombination,over PbI2 residue can also lead to electronic insulation in the grain boundary and deteriorate the device performance.However,the impact and regulation of PbI2 residue on the device performance and stability is still not fully understood.Herein,a comprehensive and detailed review is presented by discussing the PbI2 residue impact and its regulation strategies(i.e., elimination,facilitation and conversion of the residue PbI2) to manipulate the PbI2 content,distribution and forms.Finally,we also show future outlooks in this field,with an aim to help further the progression of high-efficiency and stable PSCs.
基金This work was supported financially by Korea Environment Industry&Technology Institute through Project to make multi-ministerial national biological research resources more advanced program,funded by Korea Ministry of Environment(grant number RS-2023-00230403).
文摘Objective:To evaluate the effect of the ethyl acetate fraction derived from Sargassum pallidum extract against particulate matter(PM)-induced oxidative stress and inflammation in HaCaT cells and zebrafish.Methods:HaCaT cells and zebrafish were used to evaluate the protective effects of the ethyl acetate fraction of Sargassum pallidum extract against PM-induced oxidative stress and inflammation.The production of nitric oxide(NO),intracellular ROS,prostaglandin E2(PGE2),and pro-inflammatory cytokines,and the expression levels of COX-2,iNOS,and NF-κB were evaluated in PM-induced HaCaT cells.Furthermore,the levels of ROS,NO,and lipid peroxidation were assessed in the PM-exposed zebrafish model.Results:The ethyl acetate fraction of Sargassum pallidum extract significantly decreased the production of NO,intracellular ROS,and PGE2 in PM-induced HaCaT cells.In addition,the fraction markedly suppressed the levels of pro-inflammatory cytokines and inhibited the expression levels of COX-2,iNOS,and NF-κB.Furthermore,it displayed remarkable protective effects against PM-induced inflammatory response and oxidative stress,represented by the reduction of NO,ROS,and lipid peroxidation in zebrafish.Conclusions:The ethyl acetate fraction of Sargassum pallidum extract exhibits a protective effect against PM-induced oxidative stress and inflammation both in vitro and in vivo and has the potential as a candidate for the development of pharmaceutical and cosmeceutical products.
文摘In this study,green zinc oxide(ZnO)/polypyrrole(Ppy)/cellulose acetate(CA)film has been synthesized via solvent casting.This film was used as supporting material for glucose oxidase(GOx)to sensitize a glucose biosensor.ZnO nanoparticles have been prepared via the green route using olive leaves extract as a reductant.ZnO/Ppy nanocomposite has been synthesized by a simple in-situ chemical oxidative polymerization of pyrrole(Py)monomer using ferric chloride(FeCl3)as an oxidizing agent.The produced materials and the composite films were characterized using X-ray diffraction analysis(XRD),scanning electron microscope(SEM),Fourier transform infrared(FTIR)and thermogravimetric analysis(TGA).Glucose oxidase was successfully immobilized on the surface of the prepared film and then ZnO/Ppy/CA/GOx composite was sputtered with platinum electrode for the current determination at different initial concentrations of glucose.Current measurements proved the suitability and the high sensitivity of the constructed biosensor for the detection of glucose levels in different samples.The performance of the prepared biosensor has been assessed by measuring and comparing glucose concentrations up to 800 ppm.The results affirmed the reliability of the developed biosensor towards real samples which suggests the wide-scale application of the proposed biosensor.
基金supported by the National Key Research and Development Program of China(No.2022YFC3700701)National Natural Science Foundation of China(Grant Nos.41775146,42061134009)+1 种基金USTC Research Funds of the Double First-Class Initiative(YD2080002007)Strategic Priority Research Program of Chinese Academy of Sciences(XDB41000000).
文摘Forecasting uncertainties among meteorological fields have long been recognized as the main limitation on the accuracy and predictability of air quality forecasts.However,the particular impact of meteorological forecasting uncertainties on air quality forecasts specific to different seasons is still not well known.In this study,a series of forecasts with different forecast lead times for January,April,July,and October of 2018 are conducted over the Beijing-Tianjin-Hebei(BTH)region and the impacts of meteorological forecasting uncertainties on surface PM_(2.5)concentration forecasts with each lead time are investigated.With increased lead time,the forecasted PM_(2.5)concentrations significantly change and demonstrate obvious seasonal variations.In general,the forecasting uncertainties in monthly mean surface PM_(2.5)concentrations in the BTH region due to lead time are the largest(80%)in spring,followed by autumn(~50%),summer(~40%),and winter(20%).In winter,the forecasting uncertainties in total surface PM_(2.5)mass due to lead time are mainly due to the uncertainties in PBL heights and hence the PBL mixing of anthropogenic primary particles.In spring,the forecasting uncertainties are mainly from the impacts of lead time on lower-tropospheric northwesterly winds,thereby further enhancing the condensation production of anthropogenic secondary particles by the long-range transport of natural dust.In summer,the forecasting uncertainties result mainly from the decrease in dry and wet deposition rates,which are associated with the reduction of near-surface wind speed and precipitation rate.In autumn,the forecasting uncertainties arise mainly from the change in the transport of remote natural dust and anthropogenic particles,which is associated with changes in the large-scale circulation.
基金National Natural Science Foundation of China(42230603,42275020)Guangdong Major Project of Basic and Applied Basic Research(2020B0301030004)+3 种基金Guangdong Province Key Laboratory for Climate Change and Natural Disaster Studies(2020B1212060025)Innovation Group Project of Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)(311021001)Open Fund of State Key Laboratory of Satellite Ocean Environment Dynamics,Second Institute of Oceanography,MNR(QNHX2310)Future Earth Early-Career Fellowship of the Future Earth Global Secretariat Hub China。
文摘Drought events have become more frequent and intense over East Asia in recent decades,leading to huge socioeconomic impacts.Although the droughts have been studied extensively by cases or for individual regions,their leading variability and associated causes remain unclear.Based on the Standardized Precipitation Evapotranspiration Index(SPEI)and ERA5 reanalysis product from 1979 to 2020,this study evealuates the severity of spring droughts in East Asia and investigates their variations and associated drivers.The results indicate that North China and Mongolia have experienced remarkable trends toward dryness during spring in recent decades,while southwestern China has witnessed an opposite trend toward wetness.The first Empirical Orthogonal Function mode of SPEI variability reveals a similar seesawing pattern,with more severe dryness in northwestern China,Mongolia,North China,South Korea,and Japan but increased wetness in Southwestern China and southeast Asia.Further investigation reveals that the anomalously dry(wet)surface in North(Southwestern)China is significantly associated with anomalously high(low)temperature,less(more)precipitation,and reduced(increased)soil moisture during the previous winter and early spring,regulated by an anomalous anticyclone(cyclone)and thus reduced(increased)water vapor convergence.The spring dry-wet pattern in East Asia is also linked to cold sea surface temperature anomalies in the central-eastern Pacific.The findings of this study have important implications for improving the prediction of spring drought events in East Asia.
文摘The goal is to develop a hybrid IPN network of polyvinyl acetate (PVAc) and ethylene-vinyl acetate (VAE). In this research work, the vinyl acetate (VAc)/ VAE hybrid emulsion and polyvinyl acetate emulsion (PVAc) were effectively synthesized. Emulsions with various characteristics have been developed by adjusting the weight ratios between the vinyl acetate monomer and the VAE component. The impacts on the mechanical, thermal, and physical properties of the films were investigated using tests for pencil hardness, tensile shear strength, pH, contact angle measurement, differential scanning calorimetry (DSC), and viscosity. When 5.0 weight percent VAE was added, the tensile shear strength in dry conditions decreased by 18.75% after a 24-hour bonding period, the heat resistance decreased by 26.29% (as per WATT 91) and the tensile shear strength decreased by approximately 36.52% in wet conditions (per EN 204). The pristine sample’s results were also confirmed by the contact angle test. The interpenetrating network (IPN) formation in hybrid PVAc emulsion as primary bonds does not directly attach to PVAc and VAE chains. The addition of VAE reduced the mechanical properties (at dry conditions) and heat resistance as per WATT 91. Contact angle analysis demonstrated that PVAc adhesives containing VAE had increased water resistance when compared to conventional PVA stabilised PVAc homopolymer-based adhesives. When compared to virgin PVAc Homo, the water resistance of the PVAc emulsion polymerization was enhanced by the addition of VAE.
文摘Lead(Pb) and furan are toxic agents, and persistent exposure may impair human and animal reproductive function. We therefore explored the effects of Pb and furan on male rat hypothalamic-pituitary-gonadal reproductive status, oxidative stress, inflammation, and genomic integrity. We found that co-exposure to Pb and furan reduced the activities of testicular function enzymes, endogenous antioxidant levels, total sulfhydryl group,and glutathione. Sperm abnormality, biomarkers of oxidative stress, inflammation, and p53 expression were increased in a dose-dependent manner by treatment with furan and Pb. Typical rat gonad histoarchitecture features were also damaged. Conclusively, co-exposure to Pb and furan induced male reproductive function derangement by decreasing the antioxidant defences in rats, increasing abnormalities in spermatozoa morphology, and reducing reproductive hormone in circulation. These pathophysiological alterations, if persistent, might provide a permissive environment for potentiating reproductive dysfunction and infertility.
