Sequential samples of single precipitation event were collected by the use of specially de-signed semi-automatic sequential precipitation collector in the spring of 1988 in Guilin City. ThePH value and soluble chemica...Sequential samples of single precipitation event were collected by the use of specially de-signed semi-automatic sequential precipitation collector in the spring of 1988 in Guilin City. ThePH value and soluble chemical species such as SO, NO, NH, Ca ̄(2+), Mg ̄(2+), Na ̄+, K`+, F ̄- andCl ̄- were analyzed. An apparent decrease in the concentration of all ions except H ̄+ and NO wasobserved at the initial portion of the events. The relative acidity increased as the event progress.The concentration of H ̄+ was the result of comprehensive actions of all ions. The average scavengingratio of events was calculated and it is found that SO was the major contributor for acid rain inGuilin and Ca ̄(2+) was the important neutralizer.展开更多
The below-cloud aerosol scavenging process by precipitation is one of the most important mechanisms to remove aerosols from the atmosphere.Due to its complexity and dependence on both aerosol and raindrop sizes,wet sc...The below-cloud aerosol scavenging process by precipitation is one of the most important mechanisms to remove aerosols from the atmosphere.Due to its complexity and dependence on both aerosol and raindrop sizes,wet scavenging process has been poorly treated,especially during the removal of fine particles.This makes the numerical simulation of below-cloud scavenging in large-scale aerosolmodels unrealistic.To consider the slip effects of submicron particles,a simplified expression for the diffusion scavenging was developed by approximating the Cunningham slip correction factor.The derived analytic solution was parameterized as a simple power function of rain intensity under the assumption of the lognormal size distribution of particles.The resultant approximated expression was compared to the observed data and the results of previous studies including a 3D atmospheric chemical transport model simulation.Compared with the default GEOS-Chem coefficient of 0.00106R0.61 and the observation-based coefficient of 0.0144R0.9268,the coefficient of a and b in∧m=aRb spread in the range of 0.0002-0.1959 for a and 0.3261-0.525 for b over a size distribution of GSD of 1.3–2.5 and a geometric mean diameter of 0.01-2.5μm.Overall,this study showed that the scavenging coefficient varies widely by orders of magnitude according to the size distribution of particles and rain intensity.This study also demonstrated that the obtained simplified expression could consider the theoretical approach of aerosol polydispersity.Our proposed analytic approach showed that results can be effectively applied for reduced computational burden in atmospheric modeling.展开更多
During the decommissioning of the Fukushima Daiichi nuclear power plant,it is important to consider the retrieval of resolidified debris both in air and underwater configurations.For the subsequent retrieval of debris...During the decommissioning of the Fukushima Daiichi nuclear power plant,it is important to consider the retrieval of resolidified debris both in air and underwater configurations.For the subsequent retrieval of debris from the reactor building,the resolidified debris must be cut into smaller pieces using various cutting methods.During the cutting process,aerosol particles are expected to be generated at the submicron scale.It has been noted that such aerosols sizing within the Greenfield gap(0.1-1μm)are difficult to remove effectively using traditional spraying methods.Therefore,to improve the aerosol removal efficiency of the spray system,a new aerosol agglomeration method was recently proposed,which involves injecting water mist to enlarge the sizes of the aerosol particles before removing them using water sprays.In this study,a series of experiments were performed to clarify the proper spray configurations for effective aerosol scavenging and to improve the performance of the water mist.The experimental results showed that the spray flow rate and droplet characteristics are important factors for the aerosol-scavenging efficiency and performance of the water mist.The results obtained from this study will be helpful for the optimization of the spray system design for effective aerosol scavenging during the decommissioning of the Fukushima Daiichi plant.展开更多
The gut microbiota significantly influences host physiology and provides essential ecosystem services.While diet can affect the composition of the gut microbiota,the gut microbiota can also help the host adapt to spec...The gut microbiota significantly influences host physiology and provides essential ecosystem services.While diet can affect the composition of the gut microbiota,the gut microbiota can also help the host adapt to specific dietary habits.The carrion crow(Corvus corone),an urban facultative scavenger bird,hosts an abundance of pathogens due to its scavenging behavior.Despite this,carrion crows infrequently exhibit illness,a phenomenon related to their unique physiological adaptability.At present,however,the role of the gut microbiota remains incompletely understood.In this study,we performed a comparative analysis using 16S rRNA amplicon sequencing technology to assess colonic content in carrion crows and 16 other bird species with different diets in Beijing,China.Our findings revealed that the dominant gut microbiota in carrion crows was primarily composed of Proteobacteria(75.51%)and Firmicutes(22.37%).Significant differences were observed in the relative abundance of Enterococcus faecalis among groups,highlighting its potential as a biomarker of facultative scavenging behavior in carrion crows.Subsequently,E.faecalis isolated from carrion crows was transplanted into model mice to explore the protective effects of this bacterial community against Salmonella enterica infection.Results showed that E.faecalis down-regulated the expression of pro-inflammatory cytokines tumor necrosis factor alpha(TNF-α),interferon gamma(IFN-γ),and interleukin 6(IL-6),prevented S.enterica colonization,and regulated the composition of gut microbiota in mice,thereby modulating the host’s immune regulatory capacity.Therefore,E.faecalis exerts immunoregulatory and anti-pathogenic functions in carrion crows engaged in scavenging behavior,offering a representative case of how the gut microbiota contributes to the protection of hosts with specialized diets.展开更多
Saharan dust represents more than 50%of the total desert dust emitted around the globe and its radiative effect significantly affects the atmospheric circulation at a continental scale.Previous studies on dust vertica...Saharan dust represents more than 50%of the total desert dust emitted around the globe and its radiative effect significantly affects the atmospheric circulation at a continental scale.Previous studies on dust vertical distribution and the Saharan Air Layer(SAL)showed some shortcomings that could be attributed to imperfect representation of the effects of deep convection and scavenging.The authors investigate here the role of deep convective transport and scavenging on the vertical distribution of mineral dust over Western Africa.Using multi-year(2006-2010)simulations performed with the variable-resolution(zoomed)version of the LMDZ climate model.Simulations are compared with aerosol amounts recorded by the Aerosol Robotic Network(AERONET)and with vertical profiles of the Cloud-Aerosol Lidar with Orthogonal Polarization(CALIOP)measurements.LMDZ allows a thorough examination of the respective roles of deep convective transport,convective and stratiform scavenging,boundary layer transport,and advection processes on the vertical mineral dust distribution over Western Africa.The comparison of simulated dust Aerosol Optical Depth(AOD)and distribution with measurements suggest that scavenging in deep convection and subsequent re-evaporation of dusty rainfall in the lower troposphere are critical processes for explaining the vertical distribution of desert dust.These processes play a key role in maintaining a well-defined dust layer with a sharp transition at the top of the SAL and in establishing the seasonal cycle of dust distribution.This vertical distribution is further reshaped offshore in the Inter-Tropical Convergence Zone(ITCZ)over the Atlantic Ocean by marine boundary layer turbulent and convective transport and wet deposition at the surface.展开更多
Senescence is the last developmental process in plant,which has an important impact on crop yield and quality.In this study,a stable hereditary early-senescence line BC64 was isolated from the high-generation recombin...Senescence is the last developmental process in plant,which has an important impact on crop yield and quality.In this study,a stable hereditary early-senescence line BC64 was isolated from the high-generation recombinant inbred lines of 93-11 and Wuyunjing7(W7).Genetic analysis showed that the premature aging phenotype was controlled by a dominant gene derived from 93-11.By linkage analysis,the gene was primarily mapped in the region between marker B4 and B5 near the centromere of chromosome 4,described as ES(4).Through multiple backcrossing with W7,the near-isogenic line of ES(4)(NIL-ES(4))was obtained.Compared with wild-type W7,NIL-ES(4)plants showed more sever senescence phenotype in both nature and dark conditions.In NIL plants,leaves turned yellow at the fully tillering stage;photosynthetic rate,pollen fertility and seed setting rate were decreased.Moreover,the malondialdehyde,proline content and relative conductivity in NIL-ES(4)were significantly higher than those in W7;both transcript level and activities of reactive oxygen species scavenging enzymes were repressed;H2O2 and O^(2−)were significantly accumulated.This study provides a basis for further cloning and function identification of ES(4).展开更多
The role of phoretic forces in the identification of particles acting as ice nuclei in mixed phase cloud is discussed. A method used to identify the effective ice nucleating particles is to sample ice crystals, which ...The role of phoretic forces in the identification of particles acting as ice nuclei in mixed phase cloud is discussed. A method used to identify the effective ice nucleating particles is to sample ice crystals, which are afterwards sublimated, and to examine the particles remaining after evaporation. The procedure takes into account only crystal with a maximum diameter of 20 μm, by assuming that small crystals do not scavenge aerosol during growth, and therefore that crystals contain only the effective nucleating particles. This assumption is questionable, however, as experiments have shown that even small ice crystals can scavenge aerosol. Another approach has been to compare the number and elemental composition of residual particles in small ice crystals and of aerosol near the cloud. By considering as example soot and black carbon aerosol, contradictory conclusions on their importance in the processes of ice nucleation have been reported in the literature. We suggest that, in addition to physico-chemical properties of soot/carbon aerosol particles, even the microphysical and environmental parameters involved in the transition of aerosol from gas phase to ice crystals in cloud should be considered. The contribution of phoretic forces should also be considered. After initial growth ice crystals can continue to grow by water vapour diffusion. Laboratory experiments confirm the contribution of diffusiophoresis with Stefan flow in the scavenging by snow crystals up to 3 mm in diameter. The particle scavenging efficiency of snow crystals is related to crystalline shape and depends on air relative humidity and temperature.展开更多
A crude polysaccharide was extracted from Physalis alkekengi L. fruit. HPLC was used for the component analysis of the polysaccharide. The results indicate that Physalis alkekengi L. polysaccharide(PAP) was composed...A crude polysaccharide was extracted from Physalis alkekengi L. fruit. HPLC was used for the component analysis of the polysaccharide. The results indicate that Physalis alkekengi L. polysaccharide(PAP) was composed of rhamnose, xylose, arabinose, galactose, and glucose. Free radicals scavenging activity of PAP was studied through 3 free radicals scavenging tests. PAP exhibited high scavenging effects on OH and DPPH radicals, and both the scavenging rates were about 80%. The scavenging rate of O2^- radical was about 22%.展开更多
Antioxidants have attracted the attention of researchers due to their beneficial effects as free radical scavengers. Application of a stable free radical named 1,1 diphenyl 2 picrylhydrazyl(DPPH) to screen the free ra...Antioxidants have attracted the attention of researchers due to their beneficial effects as free radical scavengers. Application of a stable free radical named 1,1 diphenyl 2 picrylhydrazyl(DPPH) to screen the free radical scavenging activity in 27 species of Chinese seaweed showed that 15 of them had significant activity in at least one of the organic solvent extracts. The most interesting seaweed species were Gelidium amansii, Gloiosiphonia capillaris, Polysiphonia urceolata, Sargassum kjellmanianum, Desmarestia viridis, and Rhodomela teres.展开更多
The Chinese dwarf cherry(Cerasus humilis(Bge.) Sok.) is a small shrub with edible fruits. It is native to northern and western China. This species was included as a medicinal plant in the ‘‘Chinese Pharmacopeia...The Chinese dwarf cherry(Cerasus humilis(Bge.) Sok.) is a small shrub with edible fruits. It is native to northern and western China. This species was included as a medicinal plant in the ‘‘Chinese Pharmacopeia’’ and has emerged as an economically important crop for fresh fruit consumption, processing into juice and wine and nutraceutical products as well. To gain a better understanding of flavonoid biosynthesis and help develop value added products and better cultivars with greater health benefits, we analyzed total flavonoid content(TFC), composition, and radical scavenging activities in fruit extracts of 16 Chinese dwarf cherry genotypes. Fruit peel TFC ranged from 33.5 to72.8 mg/g REáFW(RE: rutin equivalent, FW: fresh weight)while fruit flesh TFC ranged from 4.3 to 16.9 mg/g REáFW.An HPLC analysis revealed that fruit extracts contained 14 flavonoids with considerable variation in their profiles across genotypes. The most abundant flavonoids in most genotypes were proanthocyanidin B1(PA-B1), proanthocyanidin B2(PA-B2), phloretin 20-O-glucoside(PG), and phloretin 20,40-O-diglucoside(PDG). Principal component analysis showed that PG, PA-B1, and PA-B2 had large,positive factor loading values in the first principal component for each genotype. Increased scavenging activity of2,2-diphenyl-1-picrylhydrazyl(DPPH) radicals was apparent in genotypes ‘Nongda 4’, ‘Nongda 3’, ‘Nongda 6’,‘Wenfenli’, and ’10-32’, suggesting promising applications in the production of nutraceutical products. In summary, our results will aid in breeding, fruit processing, and developing medicinal uses of the Chinese dwarf cherry.展开更多
Objective:To study the phytochemical screening of different extracts from Citrullus colocynthis(C.colocynthis)seeds extracts and to assess their antioxidant activity on the DPPH free radical scavenging.Methods:Phytoch...Objective:To study the phytochemical screening of different extracts from Citrullus colocynthis(C.colocynthis)seeds extracts and to assess their antioxidant activity on the DPPH free radical scavenging.Methods:Phytochemical screening,total content of polyphenols and flavonoids of C.colocynthis seeds extracts,including a crude aqueous extract(E1),a defatted aqueous extract(E2),a hydromethanolic extract(HM),an ethyl acetate extract(EA)and a n-butanol extract(n-B)was carried out according to the standard methods and to assess their corresponding effect on the antioxidant activity of this plant.Results:None of these extracts contained detectable amount of alkaloid,quinone,antraquinone,or reducing sugar.Catechic tannins and flavonoids were abundant in E1,MM and EA,whilst terpenoids were abundantly present in E1 and n-B but only weekly in HM.Coumarins were found in E2,EA and n-B.Polyphenols,expressed as gallic acid equivalent,amounted,per 100 g plant matter,to 329,1002 and 150 mg in EA,HM an E1 respectively.Flavonoids,expressed as catechin equivalent,amounted.per 100 g plant matter to 620,241 and 94 mg in EA,HM and E1 respectively.Comparable values were found in n-B and E1,with lower values in E2.Quercetin,myricetin and gallic acid were found in the EA and HM extracts by thin layer chromatography,The antioxidative effect of these extracts yielded,when tested at a concentration of 2000μg/mL in a 1,1-diphenyl-2-picrylhydrazyl assay,a reducing percentage of 88.8%with EA,74.5%with HM and 66.2%with E1,and corresponding IC_(50)of 350,580and 500μg/mL as compared to 1.1μg/mL for ascorbic acid.Conclusions:These qualitative and quantitative analytical data document the presence in C.colocynthis extracts of such chemical compounds as flavonoids responsible for the antioxidant activity,as well as other biological activities of this plant.展开更多
A light purple organic active substance capable of scavenging hydroxyl radical(OH) with a high efficiency was extracted from Oyster shell at an extraction rate of 2.49%. It was found for the first time that this act...A light purple organic active substance capable of scavenging hydroxyl radical(OH) with a high efficiency was extracted from Oyster shell at an extraction rate of 2.49%. It was found for the first time that this active substance may scavenge OH with the efficiency far higher than that of vitamin C. This active substance may scavenge also superoxide radical(O2) although the scavenging efficiency is far lower than that of vitamin C. Infrared spectrometry and routine chemical analysis primarily reveal that this active substance belongs to glycoprotein.展开更多
The dynamics of Cd scavenging from solutions by Fe/Mn oxides in natural surface coatings (NSCs) was investigated under laboratory conditions. Selective extraction methods were employed to estimate the contributions ...The dynamics of Cd scavenging from solutions by Fe/Mn oxides in natural surface coatings (NSCs) was investigated under laboratory conditions. Selective extraction methods were employed to estimate the contributions of Fe/Mn oxides, where hydroxylamine hydrochloride (0.01 mol/L NH2OH-HCl + 0.01 mol/L HNO3), sodium dithionite (0.4 mol/L Na2S2O4) and nitric acid (10% HNO3) were used as extraction reagents. The Cd scavenging was accomplished with developing periods of the NSCs (totally 21 data sets). The resulting process dynamics fitted well to the Elovich equation, demonstrating that the amount of Cd scavenged was proportional to the increments of Fe/Mn oxides that were accumulated in the NSCs. The amount of Cd bound to Fe oxides (MCdFe) and Mn oxides (MCdMn) could be quantified by solving two equations based on the properties of two extraction reagents. The amount of Cd scavenged by Fe/Mn oxides could also be estimated using MCdFe and MCdMn divided by the total amounts of Fe and Mn oxides in the NSCs, respectively. The results indicated that the Cd scavenging by Fe/Mn oxides was dominated by Fe oxides, with less roles attributed to Mn oxides. The estimated levels of Cd scavenging through Fe and Mn oxides agreed well with those predicted through additive-adsorption and linear-regression models.展开更多
Objective:To investigate the antioxidant activity of soil-borne aetinobacteria.Methods:The total phenolic contents,the level of antioxidant potential by DPPH radical scavenging activity,MO scavenging activity,and ABTS...Objective:To investigate the antioxidant activity of soil-borne aetinobacteria.Methods:The total phenolic contents,the level of antioxidant potential by DPPH radical scavenging activity,MO scavenging activity,and ABTS radical scavenging activity in ethyl acelale extract were determined.Results:The 16 S rDNA sequencing analysis revealed that Streptomyces sp.strain MJM 10778.which was isolated from Hambak Mountain.Korea,has 99.9% similarity to Streptomyces misionensis(S.misionenis) NBRC 13063.The physiological and the morphological test revealed that the strain MJM 10778 has different characteristics from the strain NBRC.13063.The entire antioxidant assay with the ethyl acelale extract displayed good radical scavenging activity.The IC_(50) values of the strain MJM 10778 extract on DPPH,.NO.and ABTS radicals were identified to he 92.8 μg/mL,0.02 μg/ml,and 134.9 μg/mL,respectively.The ethyl acetate extract of the strain MJM 10778 showed an 81.500% of cell viability at 100 μg/mL in Raw264.7cell viability assay.Conclusions:The results obtained suggesl that the ethyl acetate extract of Streptomyces sp.strain MJM 10778 could be considered as a potential source of drug for the diseases that is caused by free radicals with its anti-oxidant activities and low cytotoxicity.展开更多
In vitro antioxidant activities of resveratrol and piceid against peroxynitrite(ONOO-) were examined by the inhibition of 3-nitrotyrosine formation.Trolox was used as a positive control.Resveratrol and piceid exhibi...In vitro antioxidant activities of resveratrol and piceid against peroxynitrite(ONOO-) were examined by the inhibition of 3-nitrotyrosine formation.Trolox was used as a positive control.Resveratrol and piceid exhibited high ONOO--scavenging activities in a concentration dependent manner.The antioxidant activities(the concentration of test compound required to yield a 50% inhibition of tyrosine nitration,IC 50) of resveratrol and piceid against ONOO-were(48.34±0.97) and(74.69±1.49) μmol/L,respectively.Compared with that of trolox[(105.40±1.16) μmol/L],their scavenging activities were 2.2-and 1.5-fold higher for resveratrol and piceid.Formation of nitroresveratrol as shown by UV-Vis spectroscopy and liquid chromatography-tandom mass spectrometry(LC-MS/MS) analysis indicates that resveratrol could directly scavenge ONOO-via nitration reaction.Our results demonstrate that foods and medicinal herbs with resveratrol and piceid as stronger ONOO-scavengers are valuable ingredients and have healthy application in preventing humans from peroxynitrite-mediated oxidative damage by scavenging peroxynitrite efficiently.展开更多
A new chalcone glycoside, butein-4-methoxyl-4′-O-(6"-O-acetyl)-β-D-glucopyranoside(2), along with seven known compounds, namely, quercitrin(1), luteolin-7-O-β-D-glucopyranoside(3), butein-4'-O-β-D-glucop...A new chalcone glycoside, butein-4-methoxyl-4′-O-(6"-O-acetyl)-β-D-glucopyranoside(2), along with seven known compounds, namely, quercitrin(1), luteolin-7-O-β-D-glucopyranoside(3), butein-4'-O-β-D-glucopyranoside(4), butein-4-methoxyl-4'-O-β-D-glucopyranoside(5), butin-7-O-β-D-glucopyranoside(6), isoquercitrin(7), and sulfurein(8) was isolated from aerial parts of Bidens ceruna L. Their structures were elucidated on the basis of spectroscopic studies. Compounds 1-8 were tested for their DPPH radical scavenging activity and, except compounds 2 and 5, other compounds showed scavenging activitv.展开更多
Extracts of 40 green, black or oolong high quality tea samples from China, Japan or India among others, have been prepared according to the manufacturer instructions and assayed for total polyphenols content using the...Extracts of 40 green, black or oolong high quality tea samples from China, Japan or India among others, have been prepared according to the manufacturer instructions and assayed for total polyphenols content using the Folin-Ciocalteu phenol reagent. In addition, the antioxidant activity was assessed by the CUPRAC method and the free-radical scavenging activity was determined using the antioxidant-promoting decay of the stable free-radical DPPH. Caffeine and the most important catechins were identified using RP-HPLC previously validated method. Results from this study suggest that teas, even though they content similar amounts of caffeine, differ considerably in polyphenolic content and therefore in antioxidant and free-radical scavenging activities, depending on the part of the plant used and the process applied to the material for the preparation of the final tea presentation. Correlations among Folin-Ciocalteau’s reactivity of tea samples, the neocuproine reactivity, the DPPH decolourization and the HPLC analysis suggest that the antioxidant activity is due essentially to polyphenolic compounds present in teas, mainly EGCG. The best extraction method of tea powder was the one indicated by dealers. In general, the richest samples belong to green teas and the poorest samples belong to the black teas.展开更多
Objective:To perform phytochemical screening,estimate total phenolics,flavonoids and to evaluate antioxidant potential of Moringa peregrina(M.peregrina) leaves.Methods:The dried powdered leaves of M.peregrina(150 g) w...Objective:To perform phytochemical screening,estimate total phenolics,flavonoids and to evaluate antioxidant potential of Moringa peregrina(M.peregrina) leaves.Methods:The dried powdered leaves of M.peregrina(150 g) were extracted exhaustively by Soxhlet with ethanol and then fractionated into hexane,chloroform,ethy alacetate and methanol.All the prepared extracts were also analyzed by gas chromatography-mass spectrometry to identify and characterize the chemical compounds present in the crude extracts.Folin- Ciocalteu reagent and aluminium chloride colorimetric methods were used to estimate total phenolic and flavonoid content of extracts.Hydrogen peroxide and 1,1 diphenyl-2-picrylhydrazyl were used to determine in vitro antioxidant activity.Results:Phytochemical analysis of ethanol extract showed presence of major classes of phytochemicals.Gas chromatography-mass spectrometry results revealed presence of 19 phytoconstituents in hexane extract,6 in ethyl acetate and 7 compounds in methanolic extract.Methanol extract was found to contain the highest phenolic content and flavonoids.In vitro antioxidant activities of all crude extracts were significant and comparable with the standard ascorbic acid.Conclusions:Results of this study show that the leaves of M.peregrina are the rich source of phenolic compounds that can play an important role in preventing the progression of many diseases.展开更多
The phenolic extracts of the seeds of African yam bean (Sphenostylis stenocarpa) were studied using different extraction solvents (70% ethanol, 80% acetone and acidic 70% acetone) and two heat treatment methods (dry h...The phenolic extracts of the seeds of African yam bean (Sphenostylis stenocarpa) were studied using different extraction solvents (70% ethanol, 80% acetone and acidic 70% acetone) and two heat treatment methods (dry heating on a hot plate with acid-washed sea sand at 135℃ for 25 min and wet heating in an autoclave at 120℃ for 20 min). The study examined the total phenolic content (TPC), total flavonoid content (TFC), and condensed tannin content (CTC) of the seed extracts, as well as their free radical scavenging and antioxidant properties. The raw African yam bean seed was dry heated in air oven at 100℃ for 5 min (control). Heat treatments application affected the phenolic contents of the seeds significantly (p < 0.05). The free radical scavenging activity of the phenolics were done using 2,2-diphenyl- 1-picrylhydrazyl (DPPH). The effectiveness of the extract was determined using DPPH at 50 mg/g, 10 mg/g and 5 mg/g of the extracts. At 5 mg/g, the extract was most effective indicating that higher concentration of extract gave higher antioxidant activity. The seed has high antioxidant capacity and an appreciable amount of phenolic extracts.展开更多
文摘Sequential samples of single precipitation event were collected by the use of specially de-signed semi-automatic sequential precipitation collector in the spring of 1988 in Guilin City. ThePH value and soluble chemical species such as SO, NO, NH, Ca ̄(2+), Mg ̄(2+), Na ̄+, K`+, F ̄- andCl ̄- were analyzed. An apparent decrease in the concentration of all ions except H ̄+ and NO wasobserved at the initial portion of the events. The relative acidity increased as the event progress.The concentration of H ̄+ was the result of comprehensive actions of all ions. The average scavengingratio of events was calculated and it is found that SO was the major contributor for acid rain inGuilin and Ca ̄(2+) was the important neutralizer.
基金supported by the FRIEND(Fine Particle Research Initiative in East Asia Considering National Differences)Project through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(No.2020M3G1A1114617)the Technology Development Program to Solve Climate Changes through the National Research Foundation of Korea(NRF)funded by the Ministry of Science,ICT(No.2019M1A2A2103953)+1 种基金the National Research Foundation of Korea Grant from the Korean Government(MSIT)(Nos.NRF2021M1A5A1065672/PN22011,NRF2021R1F1A1046878,and NRF2020R1A2C1003215)This research was also supported by Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(No.2020R1A6A1A03044834).
文摘The below-cloud aerosol scavenging process by precipitation is one of the most important mechanisms to remove aerosols from the atmosphere.Due to its complexity and dependence on both aerosol and raindrop sizes,wet scavenging process has been poorly treated,especially during the removal of fine particles.This makes the numerical simulation of below-cloud scavenging in large-scale aerosolmodels unrealistic.To consider the slip effects of submicron particles,a simplified expression for the diffusion scavenging was developed by approximating the Cunningham slip correction factor.The derived analytic solution was parameterized as a simple power function of rain intensity under the assumption of the lognormal size distribution of particles.The resultant approximated expression was compared to the observed data and the results of previous studies including a 3D atmospheric chemical transport model simulation.Compared with the default GEOS-Chem coefficient of 0.00106R0.61 and the observation-based coefficient of 0.0144R0.9268,the coefficient of a and b in∧m=aRb spread in the range of 0.0002-0.1959 for a and 0.3261-0.525 for b over a size distribution of GSD of 1.3–2.5 and a geometric mean diameter of 0.01-2.5μm.Overall,this study showed that the scavenging coefficient varies widely by orders of magnitude according to the size distribution of particles and rain intensity.This study also demonstrated that the obtained simplified expression could consider the theoretical approach of aerosol polydispersity.Our proposed analytic approach showed that results can be effectively applied for reduced computational burden in atmospheric modeling.
基金financially supported by the Nuclear Energy Science and Technology and Human Resource Development Project of the Japan Atomic Energy Agency/Collaborative Laboratories for Advanced Decommissioning Science(No.R04I034)Ruicong Xu appreciates the scholarship(financial support)from the Chinese Scholarship Council(CSC No.202106380073).
文摘During the decommissioning of the Fukushima Daiichi nuclear power plant,it is important to consider the retrieval of resolidified debris both in air and underwater configurations.For the subsequent retrieval of debris from the reactor building,the resolidified debris must be cut into smaller pieces using various cutting methods.During the cutting process,aerosol particles are expected to be generated at the submicron scale.It has been noted that such aerosols sizing within the Greenfield gap(0.1-1μm)are difficult to remove effectively using traditional spraying methods.Therefore,to improve the aerosol removal efficiency of the spray system,a new aerosol agglomeration method was recently proposed,which involves injecting water mist to enlarge the sizes of the aerosol particles before removing them using water sprays.In this study,a series of experiments were performed to clarify the proper spray configurations for effective aerosol scavenging and to improve the performance of the water mist.The experimental results showed that the spray flow rate and droplet characteristics are important factors for the aerosol-scavenging efficiency and performance of the water mist.The results obtained from this study will be helpful for the optimization of the spray system design for effective aerosol scavenging during the decommissioning of the Fukushima Daiichi plant.
基金supported by the National Key Research and Development Program of China(2022YFC2601602)Major Program of National Natural Science Foundation of China(32090023)Beijing Wildlife Rescue Center,China。
文摘The gut microbiota significantly influences host physiology and provides essential ecosystem services.While diet can affect the composition of the gut microbiota,the gut microbiota can also help the host adapt to specific dietary habits.The carrion crow(Corvus corone),an urban facultative scavenger bird,hosts an abundance of pathogens due to its scavenging behavior.Despite this,carrion crows infrequently exhibit illness,a phenomenon related to their unique physiological adaptability.At present,however,the role of the gut microbiota remains incompletely understood.In this study,we performed a comparative analysis using 16S rRNA amplicon sequencing technology to assess colonic content in carrion crows and 16 other bird species with different diets in Beijing,China.Our findings revealed that the dominant gut microbiota in carrion crows was primarily composed of Proteobacteria(75.51%)and Firmicutes(22.37%).Significant differences were observed in the relative abundance of Enterococcus faecalis among groups,highlighting its potential as a biomarker of facultative scavenging behavior in carrion crows.Subsequently,E.faecalis isolated from carrion crows was transplanted into model mice to explore the protective effects of this bacterial community against Salmonella enterica infection.Results showed that E.faecalis down-regulated the expression of pro-inflammatory cytokines tumor necrosis factor alpha(TNF-α),interferon gamma(IFN-γ),and interleukin 6(IL-6),prevented S.enterica colonization,and regulated the composition of gut microbiota in mice,thereby modulating the host’s immune regulatory capacity.Therefore,E.faecalis exerts immunoregulatory and anti-pathogenic functions in carrion crows engaged in scavenging behavior,offering a representative case of how the gut microbiota contributes to the protection of hosts with specialized diets.
基金The authors wish to thank the Ecosystem Approach to the management of fisheries and the marine environment in the West African Waters(AWA)project.They also acknowledge support from the international joint laboratory ECLAIRS.The Laboratoire de Météorologie Dynamique(LMD)and the Global Challenges Research Fund(GCRF)African Science for Weather Information and Techniques(SWIFT)Programme.NASA,CNES,and ICARE are acknowledged for providing access to CALIOP and Sun photometer AERONET data.
文摘Saharan dust represents more than 50%of the total desert dust emitted around the globe and its radiative effect significantly affects the atmospheric circulation at a continental scale.Previous studies on dust vertical distribution and the Saharan Air Layer(SAL)showed some shortcomings that could be attributed to imperfect representation of the effects of deep convection and scavenging.The authors investigate here the role of deep convective transport and scavenging on the vertical distribution of mineral dust over Western Africa.Using multi-year(2006-2010)simulations performed with the variable-resolution(zoomed)version of the LMDZ climate model.Simulations are compared with aerosol amounts recorded by the Aerosol Robotic Network(AERONET)and with vertical profiles of the Cloud-Aerosol Lidar with Orthogonal Polarization(CALIOP)measurements.LMDZ allows a thorough examination of the respective roles of deep convective transport,convective and stratiform scavenging,boundary layer transport,and advection processes on the vertical mineral dust distribution over Western Africa.The comparison of simulated dust Aerosol Optical Depth(AOD)and distribution with measurements suggest that scavenging in deep convection and subsequent re-evaporation of dusty rainfall in the lower troposphere are critical processes for explaining the vertical distribution of desert dust.These processes play a key role in maintaining a well-defined dust layer with a sharp transition at the top of the SAL and in establishing the seasonal cycle of dust distribution.This vertical distribution is further reshaped offshore in the Inter-Tropical Convergence Zone(ITCZ)over the Atlantic Ocean by marine boundary layer turbulent and convective transport and wet deposition at the surface.
基金supported by grants from the Science Foundation of Jiangxi Province(Grant No.20212ACB215003)the National Natural Science Foundation of China(Grant No.31960403).
文摘Senescence is the last developmental process in plant,which has an important impact on crop yield and quality.In this study,a stable hereditary early-senescence line BC64 was isolated from the high-generation recombinant inbred lines of 93-11 and Wuyunjing7(W7).Genetic analysis showed that the premature aging phenotype was controlled by a dominant gene derived from 93-11.By linkage analysis,the gene was primarily mapped in the region between marker B4 and B5 near the centromere of chromosome 4,described as ES(4).Through multiple backcrossing with W7,the near-isogenic line of ES(4)(NIL-ES(4))was obtained.Compared with wild-type W7,NIL-ES(4)plants showed more sever senescence phenotype in both nature and dark conditions.In NIL plants,leaves turned yellow at the fully tillering stage;photosynthetic rate,pollen fertility and seed setting rate were decreased.Moreover,the malondialdehyde,proline content and relative conductivity in NIL-ES(4)were significantly higher than those in W7;both transcript level and activities of reactive oxygen species scavenging enzymes were repressed;H2O2 and O^(2−)were significantly accumulated.This study provides a basis for further cloning and function identification of ES(4).
文摘The role of phoretic forces in the identification of particles acting as ice nuclei in mixed phase cloud is discussed. A method used to identify the effective ice nucleating particles is to sample ice crystals, which are afterwards sublimated, and to examine the particles remaining after evaporation. The procedure takes into account only crystal with a maximum diameter of 20 μm, by assuming that small crystals do not scavenge aerosol during growth, and therefore that crystals contain only the effective nucleating particles. This assumption is questionable, however, as experiments have shown that even small ice crystals can scavenge aerosol. Another approach has been to compare the number and elemental composition of residual particles in small ice crystals and of aerosol near the cloud. By considering as example soot and black carbon aerosol, contradictory conclusions on their importance in the processes of ice nucleation have been reported in the literature. We suggest that, in addition to physico-chemical properties of soot/carbon aerosol particles, even the microphysical and environmental parameters involved in the transition of aerosol from gas phase to ice crystals in cloud should be considered. The contribution of phoretic forces should also be considered. After initial growth ice crystals can continue to grow by water vapour diffusion. Laboratory experiments confirm the contribution of diffusiophoresis with Stefan flow in the scavenging by snow crystals up to 3 mm in diameter. The particle scavenging efficiency of snow crystals is related to crystalline shape and depends on air relative humidity and temperature.
基金Supported by the Science and Technique Foundation of Jilin Province, China(No20020503-2)
文摘A crude polysaccharide was extracted from Physalis alkekengi L. fruit. HPLC was used for the component analysis of the polysaccharide. The results indicate that Physalis alkekengi L. polysaccharide(PAP) was composed of rhamnose, xylose, arabinose, galactose, and glucose. Free radicals scavenging activity of PAP was studied through 3 free radicals scavenging tests. PAP exhibited high scavenging effects on OH and DPPH radicals, and both the scavenging rates were about 80%. The scavenging rate of O2^- radical was about 22%.
文摘Antioxidants have attracted the attention of researchers due to their beneficial effects as free radical scavengers. Application of a stable free radical named 1,1 diphenyl 2 picrylhydrazyl(DPPH) to screen the free radical scavenging activity in 27 species of Chinese seaweed showed that 15 of them had significant activity in at least one of the organic solvent extracts. The most interesting seaweed species were Gelidium amansii, Gloiosiphonia capillaris, Polysiphonia urceolata, Sargassum kjellmanianum, Desmarestia viridis, and Rhodomela teres.
基金financially supported by the Major Subject of Shanxi Science and Technology Research(Grant No.20121101010)the Platform Construction of Science and Technology of Shanxi Province(Grant No.2013091004-0101)the Doctoral Research Fund of Shanxi Agriculture University(Grant No.2015ZZ19)
文摘The Chinese dwarf cherry(Cerasus humilis(Bge.) Sok.) is a small shrub with edible fruits. It is native to northern and western China. This species was included as a medicinal plant in the ‘‘Chinese Pharmacopeia’’ and has emerged as an economically important crop for fresh fruit consumption, processing into juice and wine and nutraceutical products as well. To gain a better understanding of flavonoid biosynthesis and help develop value added products and better cultivars with greater health benefits, we analyzed total flavonoid content(TFC), composition, and radical scavenging activities in fruit extracts of 16 Chinese dwarf cherry genotypes. Fruit peel TFC ranged from 33.5 to72.8 mg/g REáFW(RE: rutin equivalent, FW: fresh weight)while fruit flesh TFC ranged from 4.3 to 16.9 mg/g REáFW.An HPLC analysis revealed that fruit extracts contained 14 flavonoids with considerable variation in their profiles across genotypes. The most abundant flavonoids in most genotypes were proanthocyanidin B1(PA-B1), proanthocyanidin B2(PA-B2), phloretin 20-O-glucoside(PG), and phloretin 20,40-O-diglucoside(PDG). Principal component analysis showed that PG, PA-B1, and PA-B2 had large,positive factor loading values in the first principal component for each genotype. Increased scavenging activity of2,2-diphenyl-1-picrylhydrazyl(DPPH) radicals was apparent in genotypes ‘Nongda 4’, ‘Nongda 3’, ‘Nongda 6’,‘Wenfenli’, and ’10-32’, suggesting promising applications in the production of nutraceutical products. In summary, our results will aid in breeding, fruit processing, and developing medicinal uses of the Chinese dwarf cherry.
文摘Objective:To study the phytochemical screening of different extracts from Citrullus colocynthis(C.colocynthis)seeds extracts and to assess their antioxidant activity on the DPPH free radical scavenging.Methods:Phytochemical screening,total content of polyphenols and flavonoids of C.colocynthis seeds extracts,including a crude aqueous extract(E1),a defatted aqueous extract(E2),a hydromethanolic extract(HM),an ethyl acetate extract(EA)and a n-butanol extract(n-B)was carried out according to the standard methods and to assess their corresponding effect on the antioxidant activity of this plant.Results:None of these extracts contained detectable amount of alkaloid,quinone,antraquinone,or reducing sugar.Catechic tannins and flavonoids were abundant in E1,MM and EA,whilst terpenoids were abundantly present in E1 and n-B but only weekly in HM.Coumarins were found in E2,EA and n-B.Polyphenols,expressed as gallic acid equivalent,amounted,per 100 g plant matter,to 329,1002 and 150 mg in EA,HM an E1 respectively.Flavonoids,expressed as catechin equivalent,amounted.per 100 g plant matter to 620,241 and 94 mg in EA,HM and E1 respectively.Comparable values were found in n-B and E1,with lower values in E2.Quercetin,myricetin and gallic acid were found in the EA and HM extracts by thin layer chromatography,The antioxidative effect of these extracts yielded,when tested at a concentration of 2000μg/mL in a 1,1-diphenyl-2-picrylhydrazyl assay,a reducing percentage of 88.8%with EA,74.5%with HM and 66.2%with E1,and corresponding IC_(50)of 350,580and 500μg/mL as compared to 1.1μg/mL for ascorbic acid.Conclusions:These qualitative and quantitative analytical data document the presence in C.colocynthis extracts of such chemical compounds as flavonoids responsible for the antioxidant activity,as well as other biological activities of this plant.
基金Supported by the Natural Science Foundation of Fujian Province, China(NoC0510029)the Specialized Foundation for Creative Team of Young and Middle-aged Teachers of Jimei University, China(No2006A003)
文摘A light purple organic active substance capable of scavenging hydroxyl radical(OH) with a high efficiency was extracted from Oyster shell at an extraction rate of 2.49%. It was found for the first time that this active substance may scavenge OH with the efficiency far higher than that of vitamin C. This active substance may scavenge also superoxide radical(O2) although the scavenging efficiency is far lower than that of vitamin C. Infrared spectrometry and routine chemical analysis primarily reveal that this active substance belongs to glycoprotein.
基金The National Basic Research Program (973) of China (No. 2004CB3418501)
文摘The dynamics of Cd scavenging from solutions by Fe/Mn oxides in natural surface coatings (NSCs) was investigated under laboratory conditions. Selective extraction methods were employed to estimate the contributions of Fe/Mn oxides, where hydroxylamine hydrochloride (0.01 mol/L NH2OH-HCl + 0.01 mol/L HNO3), sodium dithionite (0.4 mol/L Na2S2O4) and nitric acid (10% HNO3) were used as extraction reagents. The Cd scavenging was accomplished with developing periods of the NSCs (totally 21 data sets). The resulting process dynamics fitted well to the Elovich equation, demonstrating that the amount of Cd scavenged was proportional to the increments of Fe/Mn oxides that were accumulated in the NSCs. The amount of Cd bound to Fe oxides (MCdFe) and Mn oxides (MCdMn) could be quantified by solving two equations based on the properties of two extraction reagents. The amount of Cd scavenged by Fe/Mn oxides could also be estimated using MCdFe and MCdMn divided by the total amounts of Fe and Mn oxides in the NSCs, respectively. The results indicated that the Cd scavenging by Fe/Mn oxides was dominated by Fe oxides, with less roles attributed to Mn oxides. The estimated levels of Cd scavenging through Fe and Mn oxides agreed well with those predicted through additive-adsorption and linear-regression models.
基金supported by a grant from next-generation BioGreen 21 pmjcet(No.PJ009643).RDA Korea
文摘Objective:To investigate the antioxidant activity of soil-borne aetinobacteria.Methods:The total phenolic contents,the level of antioxidant potential by DPPH radical scavenging activity,MO scavenging activity,and ABTS radical scavenging activity in ethyl acelale extract were determined.Results:The 16 S rDNA sequencing analysis revealed that Streptomyces sp.strain MJM 10778.which was isolated from Hambak Mountain.Korea,has 99.9% similarity to Streptomyces misionensis(S.misionenis) NBRC 13063.The physiological and the morphological test revealed that the strain MJM 10778 has different characteristics from the strain NBRC.13063.The entire antioxidant assay with the ethyl acelale extract displayed good radical scavenging activity.The IC_(50) values of the strain MJM 10778 extract on DPPH,.NO.and ABTS radicals were identified to he 92.8 μg/mL,0.02 μg/ml,and 134.9 μg/mL,respectively.The ethyl acetate extract of the strain MJM 10778 showed an 81.500% of cell viability at 100 μg/mL in Raw264.7cell viability assay.Conclusions:The results obtained suggesl that the ethyl acetate extract of Streptomyces sp.strain MJM 10778 could be considered as a potential source of drug for the diseases that is caused by free radicals with its anti-oxidant activities and low cytotoxicity.
基金Supported by the National Basic Research Program of China(Nos.2012CB721105,2011CBA00802,2007CB714301)the National Natural Science Foundation of China(No.30873400)the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20090032110015)
文摘In vitro antioxidant activities of resveratrol and piceid against peroxynitrite(ONOO-) were examined by the inhibition of 3-nitrotyrosine formation.Trolox was used as a positive control.Resveratrol and piceid exhibited high ONOO--scavenging activities in a concentration dependent manner.The antioxidant activities(the concentration of test compound required to yield a 50% inhibition of tyrosine nitration,IC 50) of resveratrol and piceid against ONOO-were(48.34±0.97) and(74.69±1.49) μmol/L,respectively.Compared with that of trolox[(105.40±1.16) μmol/L],their scavenging activities were 2.2-and 1.5-fold higher for resveratrol and piceid.Formation of nitroresveratrol as shown by UV-Vis spectroscopy and liquid chromatography-tandom mass spectrometry(LC-MS/MS) analysis indicates that resveratrol could directly scavenge ONOO-via nitration reaction.Our results demonstrate that foods and medicinal herbs with resveratrol and piceid as stronger ONOO-scavengers are valuable ingredients and have healthy application in preventing humans from peroxynitrite-mediated oxidative damage by scavenging peroxynitrite efficiently.
文摘A new chalcone glycoside, butein-4-methoxyl-4′-O-(6"-O-acetyl)-β-D-glucopyranoside(2), along with seven known compounds, namely, quercitrin(1), luteolin-7-O-β-D-glucopyranoside(3), butein-4'-O-β-D-glucopyranoside(4), butein-4-methoxyl-4'-O-β-D-glucopyranoside(5), butin-7-O-β-D-glucopyranoside(6), isoquercitrin(7), and sulfurein(8) was isolated from aerial parts of Bidens ceruna L. Their structures were elucidated on the basis of spectroscopic studies. Compounds 1-8 were tested for their DPPH radical scavenging activity and, except compounds 2 and 5, other compounds showed scavenging activitv.
文摘Extracts of 40 green, black or oolong high quality tea samples from China, Japan or India among others, have been prepared according to the manufacturer instructions and assayed for total polyphenols content using the Folin-Ciocalteu phenol reagent. In addition, the antioxidant activity was assessed by the CUPRAC method and the free-radical scavenging activity was determined using the antioxidant-promoting decay of the stable free-radical DPPH. Caffeine and the most important catechins were identified using RP-HPLC previously validated method. Results from this study suggest that teas, even though they content similar amounts of caffeine, differ considerably in polyphenolic content and therefore in antioxidant and free-radical scavenging activities, depending on the part of the plant used and the process applied to the material for the preparation of the final tea presentation. Correlations among Folin-Ciocalteau’s reactivity of tea samples, the neocuproine reactivity, the DPPH decolourization and the HPLC analysis suggest that the antioxidant activity is due essentially to polyphenolic compounds present in teas, mainly EGCG. The best extraction method of tea powder was the one indicated by dealers. In general, the richest samples belong to green teas and the poorest samples belong to the black teas.
基金Supported by the Department of Pharmacy.Oman MedicalCollege.Muscat,Oman(Grant No.OMC-PHAR/425-05/13)
文摘Objective:To perform phytochemical screening,estimate total phenolics,flavonoids and to evaluate antioxidant potential of Moringa peregrina(M.peregrina) leaves.Methods:The dried powdered leaves of M.peregrina(150 g) were extracted exhaustively by Soxhlet with ethanol and then fractionated into hexane,chloroform,ethy alacetate and methanol.All the prepared extracts were also analyzed by gas chromatography-mass spectrometry to identify and characterize the chemical compounds present in the crude extracts.Folin- Ciocalteu reagent and aluminium chloride colorimetric methods were used to estimate total phenolic and flavonoid content of extracts.Hydrogen peroxide and 1,1 diphenyl-2-picrylhydrazyl were used to determine in vitro antioxidant activity.Results:Phytochemical analysis of ethanol extract showed presence of major classes of phytochemicals.Gas chromatography-mass spectrometry results revealed presence of 19 phytoconstituents in hexane extract,6 in ethyl acetate and 7 compounds in methanolic extract.Methanol extract was found to contain the highest phenolic content and flavonoids.In vitro antioxidant activities of all crude extracts were significant and comparable with the standard ascorbic acid.Conclusions:Results of this study show that the leaves of M.peregrina are the rich source of phenolic compounds that can play an important role in preventing the progression of many diseases.
文摘The phenolic extracts of the seeds of African yam bean (Sphenostylis stenocarpa) were studied using different extraction solvents (70% ethanol, 80% acetone and acidic 70% acetone) and two heat treatment methods (dry heating on a hot plate with acid-washed sea sand at 135℃ for 25 min and wet heating in an autoclave at 120℃ for 20 min). The study examined the total phenolic content (TPC), total flavonoid content (TFC), and condensed tannin content (CTC) of the seed extracts, as well as their free radical scavenging and antioxidant properties. The raw African yam bean seed was dry heated in air oven at 100℃ for 5 min (control). Heat treatments application affected the phenolic contents of the seeds significantly (p < 0.05). The free radical scavenging activity of the phenolics were done using 2,2-diphenyl- 1-picrylhydrazyl (DPPH). The effectiveness of the extract was determined using DPPH at 50 mg/g, 10 mg/g and 5 mg/g of the extracts. At 5 mg/g, the extract was most effective indicating that higher concentration of extract gave higher antioxidant activity. The seed has high antioxidant capacity and an appreciable amount of phenolic extracts.