It is necessary to understand all the prerequisites, which result in gas hydrate formation for safe design and control of a variety of processes in petroleum industry. Thermodynamic hydrate inhibitors (THIs) are norma...It is necessary to understand all the prerequisites, which result in gas hydrate formation for safe design and control of a variety of processes in petroleum industry. Thermodynamic hydrate inhibitors (THIs) are normally used to preclude gas hydrate formation by shifting hydrate stability region to lower temperatures and higher pressures. Sometimes, it is difficult to avoid hydrate formation and hydrates will form anyway. In this situation, kinetic hydrate inhibitors (KHIs) can be used to postpone formation of gas hydrates by retarding hydrate nucleation and growth rate. In this study, two kinetic parameters including natural gas hydrate formation induction time and the rate of gas consumption were experimentally investigated in the presence of monoethylene glycol (MEG), L-tyrosine, and polyvinylpyrrolidone (PVP) at various concentrations in aqueous solutions. Since hydrate formation is a stochastic phenomenon, the repeatability of each kinetic parameter was evaluated several times and the average values for the hydrate formation induction times and the rates of gas consumption are reported. The results indicate that from the view point of hydrate formation induction time, 2 wt% PVP and 20 wt% MEG aqueous solutions have the highest values and are the best choices. It is also interpreted from the results that from the view point of the rate of gas consumption, 20 wt% MEG aqueous solution yields the lowest value and is the best choice. Finally, it is concluded that the combination of PVP and MEG in an aqueous solution has a simultaneous synergistic impact on natural gas hydrate formation induction time and the rate of gas consumption. Furthermore, a semi-empirical model based on chemical kinetic theory is applied to evaluate the hydrate formation induction time data. A good agreement between the experimental and calculated hydrate formation induction time data is observed.展开更多
In order to distinguish the source and migration direction of natural gas by geochemical characteristics of butane,the components and carbon isotopes of natural gas from major hydrocarbonbearing basins in China were a...In order to distinguish the source and migration direction of natural gas by geochemical characteristics of butane,the components and carbon isotopes of natural gas from major hydrocarbonbearing basins in China were analyzed.The results showed that：（1） Oil-type gas has i-C 4 /n-C 4 0.8,δ 13 C butane -28‰,δ 13 C i-butane -27‰,δ 13 C n-butane -28.5‰,whereas coal-type gas has i-C 4 /n-C 4 0.8,δ 13 C butane -25.5‰,δ 13 C i-butane -24‰,δ 13 C n-butane -26‰.（2） When δ 13 C i-butane-δ 13 C n-butane is greater than 0,the maturity of oil-type gas is generally more than 2.4% and that of coal-type gas is greater than 1.4%,whereas when the difference is less than 0,the maturity of oil-type gas is generally less than 1.1% and that of coal-type gas is less than 0.8%.（3） When natural gas migrates through dense cap rocks,the value of i-C 4 /n-C 4 increases,whereas when it migrates laterally along a reservoir,the value of i-C 4 /n-C 4 decreases.（4） Sapropelic transition zone gas with composition and carbon isotopic signatures similar to those of oil-type gas in the low thermal evolution stage is found to have a relatively high butane content.（5） The values of i-C 4 /n-C 4 and δ 13 C n-butane δ 13 C i-butane of gas which has suffered biological degradation are significantly higher than those obtained from thermogenic and bio-thermocatalytic transition zone gas.Thus,natural gas of different genetic types can be recognized through component analysis and carbon isotopic signatures of butane,the natural gas maturity can be estimated from the difference in carbon isotopic content between isobutane and n-butane,and the migration direction of natural gas can be determined from i-C 4 /n-C 4 ratios and transport conditions,which can also be used to thermogenic and bio-thermocatalytic transition zone gas.展开更多
Environmental sociology and the sociology of natural resources are two key subdisciplines of the sociological study on the interactions between nature and human society.Previous discussion on the relationships of thes...Environmental sociology and the sociology of natural resources are two key subdisciplines of the sociological study on the interactions between nature and human society.Previous discussion on the relationships of these two fields has largely focused on their distinctions and synthesis in western(particularly American) academia.Environmental sociology emerged as an important sociological subdiscipline in China in the early 1990s and is under vigorous disciplinary construction at present.By contrast,the sociology of natural resources is still a novel term for most Chinese researchers.This article provides a systematic review of recent literature on the relationships between environmental and natural resource sociologies,which should provide important implications for the further development of environmental sociology in China.展开更多
Influenza virus poses a significant threat to global public health,causing serious repercussions on human life and social well-being.Over the past decades,various antiviral drugs targeting either the virus itself or i...Influenza virus poses a significant threat to global public health,causing serious repercussions on human life and social well-being.Over the past decades,various antiviral drugs targeting either the virus itself or its host were identified.However,the emergence of drug-resistant influenza virus strains has posed a critical challenge to the effectiveness of these existing anti-influenza agents .Consequently,there is an urgent need to develop novel molecules with new chemical frameworks.Macrocyclic natural products serve as a crucial resource for validating targets and discovering lead compounds.However,the number of naturlly crring macrocyclic natural products is limited due to inherent biosynthetic pathways,which restricts the development of macrocyclic drugs.In contrast,artificially synthesized pseudonatural products show enhanced availability and greater structural diversity,while possessing similar biological functions[5]and have attracted significant interest from medicinal chemists.Hence,it is valuable to develop effective synthetic methods to expedite the discovery of macrocyclic lead compounds.展开更多
Natural Products always exhibit more intellectual bioactivities and atom economy,and it’s also an important source of innovative drugs.Prof.SUN Han-Dong,Academician of Chinese Academy of Sciences from Kunming Institu...Natural Products always exhibit more intellectual bioactivities and atom economy,and it’s also an important source of innovative drugs.Prof.SUN Han-Dong,Academician of Chinese Academy of Sciences from Kunming Institute of Botany,has made outstanding contributions to natural product chemistry,andsetagoodexamplefor ouryounggeneration.Onthe occasion ofProfSun’s 80th birthday,I’d like to express my deep respect to him,and wish Prof.SUN a happy birthday and good health.展开更多
Alfalfa (Medicago sativa L.) is an important forage and conservation crop in North America but occurrences of naturalized alfalfa in rangelands are rare. A naturalized population of yellow-flowered alfalfa in mixed-gr...Alfalfa (Medicago sativa L.) is an important forage and conservation crop in North America but occurrences of naturalized alfalfa in rangelands are rare. A naturalized population of yellow-flowered alfalfa in mixed-grass prairie on the Grand River National Grassland in South Dakota has potential agricultural value for the region. Despite this value, the distribution pattern of this alfalfa among and within native plant communities in the northern Great Plains is unknown. Field studies were conducted from 2003 through 2006 along topographic positions at two sites where yellow-flowered alfalfa was naturalized to evaluate the relationships of yellow-flowered alfalfa on biomass production, cover, species diversity, and alfalfa seedbank distribution characteristics. High yellow-flowered alfalfa cover (>50%) was associated with increased total biomass and occurred exclusively in swales and toeslopes that had silty loam soils. However, species diversity and non-alfalfa biomass were reduced when yellow-flowered alfalfa cover was high. Yellow-flowered alfalfa cover was lower and species richness was higher on backslopes and shoulder areas where sandy loam soils were present. A strong positive linear association existed between yellow-flowered alfalfa cover and alfalfa seedbank density (r values ranged from 0.76 to 0.82, P < 0.0001). Greater than 99% of the seeds were viable but germination rate was only 4%, indicating a high percentage of hard seed in this alfalfa population. Naturalized yellow-flowered alfalfa was a dominant component of a stable, low diversity plant community composed of mainly introduced species in rich soils of swales/toeslopes that contributed to forage production and quality in mixed-grass prairie in the northern Great Plains.展开更多
Caspian Gas into Balkans over medium to long term becames Albanian case on June 2013 when TAP route was selected. After Albanian National Territory Council approved TAP AG＇s Compound Development Permit, the project s...Caspian Gas into Balkans over medium to long term becames Albanian case on June 2013 when TAP route was selected. After Albanian National Territory Council approved TAP AG＇s Compound Development Permit, the project should start Construction Phase 1. Existing gas pipeline connections of Albania within the European network via TAP, is highly estimated by energy authorities in both technical and regulating aspects. New pipelines are projected to be build in order to meet local energy consume and seasonal fluctuations, as well as needs of Kosovo and FYROM. Some of important points： determination on the capacity sector building for a due Albanian Gas Market Model, supply options on the future gasification, alternatives of opening underground gas storages in the salt domes of Dumre region and extending pipelines to neighboring countries. By assistance of the Secretariat of Energy Community, MEI starts drafting the new gas law to meet Third Energy Package. TAP project, IAP project, Albania-Kosovo Pipeline, an LNG plant and terminals coastal construction, can contribute on the diversification of gas supply. Underground Gas Storage potentials are geologic solution target, considering the Upper Miocene depleted sandstone gas fields of Divjaka, as well as the Dumre evaporitic deposits diapir of the Upper Triassic.展开更多
The problem of solid waste landfills on Caspian Sea coastlines is one of the current concerns of the Iranian environmental authorities. Physical and environmental constraints as well as shortcomings in present municip...The problem of solid waste landfills on Caspian Sea coastlines is one of the current concerns of the Iranian environmental authorities. Physical and environmental constraints as well as shortcomings in present municipal solid waste management are the main factors for environmental pollution and natural resources destruction in this geographical region. In order to reduce the above problems, this study has been carried out on the basis of a comparative assessment of the existing condition of landfill sites in natural ecosystems. In this study, 48 cities of the region have been investigated. All of them are located in Gilan and Mazandaran provinces. Total daily waste production in the study area is about 1209 tons that are dumped in open spaces and/or in aquatic and terrestrial ecosystems. Surveying of 53 physical, adaptability and constraint parameters as well as hygiene and environmental parameters in the landfills, based on “Monavari-94 Method” indicate that the main problem in all of them is a high groundwater table. In 42% of landfills, the groundwater level is between from 0.5 to 2 meters. This phenomenon may cause severe risks due to the infiltration of leachate into potable groundwater. Indeed, the results of the study show that 87.5% of the landfills are located in areas with unacceptable conditions. In spite of geographical and environmental problems and constraints and as a final alternative in this respect, the need for sanitary and technical solid waste management is the main need of the study areas.展开更多
Conjugate effects heat and mass transfer on free convection flow across an isothermal sphere immersed in a viscous incompressible fluid in the presence of species concentration with radiation heat loss has been invest...Conjugate effects heat and mass transfer on free convection flow across an isothermal sphere immersed in a viscous incompressible fluid in the presence of species concentration with radiation heat loss has been investigated in this paper. The governing boundary layer equations are first transformed into a non-dimensional form and the resulting nonlinear systems of partial differential equations are then solved numerically using Finite—difference method with Keller-box Scheme. We have focused our attention on the evaluation velocity profiles, temperature profiles and species concentration profiles of the fluid as well as the local skin friction coefficient, local heat transfer rate and local species concentration transfer rate for a wide range of radiation parameter Rd, Schmidt number Sc and Prandlt number Pr.展开更多
Inflammatory bowel disease(IBD)is a chronic inflammatory illness of the intes-tine.While the mechanism underlying the pathogenesis of IBD is not fully under-stood,it is believed that a complex combination of host immu...Inflammatory bowel disease(IBD)is a chronic inflammatory illness of the intes-tine.While the mechanism underlying the pathogenesis of IBD is not fully under-stood,it is believed that a complex combination of host immunological response,environmental exposure,particularly the gut microbiota,and genetic suscept-ibility represents the major determinants.The gut virome is a group of viruses found in great frequency in the gastrointestinal tract of humans.The gut virome varies greatly among individuals and is influenced by factors including lifestyle,diet,health and disease conditions,geography,and urbanization.The majority of research has focused on the significance of gut bacteria in the progression of IBD,although viral populations represent an important component of the microbiome.We conducted this review to highlight the viral communities in the gut and their expected roles in the etiopathogenesis of IBD regarding published research to date.展开更多
In this study, an occupancy factor model was developed and used to calculate the average time spent for outdoor and indoor activities along the coastline of the Erongo region of Namibia. A closed ended questionnaire w...In this study, an occupancy factor model was developed and used to calculate the average time spent for outdoor and indoor activities along the coastline of the Erongo region of Namibia. A closed ended questionnaire was developed and administered to 800 respondents who visited the coastline for leisure, occupational and other activities. The mean time allocated for leisure activities ranges from 13.00 to 1.00 h, occupational mean time between 10.18 to 9.06 h and the values of other activities range from 16.66 to 11.00 h. The average computed time spent outdoor was found to be 11.46 h and indoor calculated to be 12.54 h. This shows an outdoor factor of 0.48 and indoor factor of 0.52 respectively. From the results obtained, the value of the absorbed dose rate ranged from 93.27 to 105.95 nGy·h<sup>ǃ</sup> and the annual effective dose rate ranged from 121.01 to 176.61 μSv·y<sup>ǃ</sup> (UNSCEAR factor) and 292.60 to 413.63 μSv·y<sup>ǃ</sup> (present factor). The values obtained for annual effective dose are higher than the acceptable limit. However, from this study, we can conclude that the use of the UNSCEAR outdoor factor in the coastline will lead to underestimation of effective dose by 24% based on the present factor.展开更多
Road traffic flow forecasting provides critical information for the operational management of road mobility challenges, and models are used to generate the forecast. This paper uses a random process to present a novel...Road traffic flow forecasting provides critical information for the operational management of road mobility challenges, and models are used to generate the forecast. This paper uses a random process to present a novel traffic modelling framework for aggregate traffic on urban roads. The main idea is that road traffic flow is random, even for the recurrent flow, such as rush hour traffic, which is predisposed to congestion. Therefore, the structure of the aggregate traffic flow model for urban roads should correlate well with the essential variables of the observed random dynamics of the traffic flow phenomena. The novelty of this paper is the developed framework, based on the Poisson process, the kinematics of urban road traffic flow, and the intermediate modelling approach, which were combined to formulate the model. Empirical data from an urban road in Ghana was used to explore the model’s fidelity. The results show that the distribution from the model correlates well with that of the empirical traffic, providing a strong validation of the new framework and instilling confidence in its potential for significantly improved forecasts and, hence, a more hopeful outlook for real-world traffic management.展开更多
Aims:Reed(Phragmites australis)is a plant species with a seasonal reproductive cycle;it has a very high biomass in U Minh Thuong National Park,in Vietnam.This study aims to evaluate fresh and dry biomass of the reed a...Aims:Reed(Phragmites australis)is a plant species with a seasonal reproductive cycle;it has a very high biomass in U Minh Thuong National Park,in Vietnam.This study aims to evaluate fresh and dry biomass of the reed and the production of biochar from the plants.The biochar is then used as a bio-organic fertilizer for watermelon cultivation in agriculture.Methods:To achieve these objectives the following experiments were conducted(1)investtigating the fresh and dry biomass of reeds producing biochar using local methods;(2)adsorption with pig urine and chemical fertilizers(nitrogen,phosphorus and potash)to examine the uptake of chemical components into the water environment;(3)mixing biochar with inorganic mineral fertilizers and peat to creat inorganic fertilizer–biochar formulas,followed by an analysis of the chemical compositions of the mixtures;(4)using various biochar-based fertilizers to grow watermelon with local varieties.Results:The results show that reeds produce very high for biomass biochar fertilizer production.Reed biochar can adsorb components of pig urine,such as ammonium,nitrate,nitrogen and phosphorus along with inorganic substances such as nitrogen,phosphorus and potash.Therefore this study proposes the use of this biochar for watermelon cultivation and environment treatment in polluted regions.Conclusions:Biomass and biochar of reed are very high.The biochar can adsorb nitrogen,phosphorus and potash fertilizers.Additionally,biochar can be mixed with peat and inorganic mineral fertilizers for to watermelon cultivation in Mekong Delta.Implications of the research:Forest fires in U Minh Thuong National Park,caused by reed vegetation,occur annually and result in damage to property and human livelihoods.This research not only exploits renewable raw materials but also helps control the risk of forest fires.Originality/Valeu:This study aims to provide methods for controlling forest fires by producing biochar of from reed(Phragmites australis)U Minh Thuong National Park Vietnam.This species thrives and produces a large biomass during the rainy season,supllying dry material that contributes to the intensity of forest fires in the dry season in Vietnam.展开更多
Human well-being and livelihoods depend on natural ecosystem services(ESs).Following the increment of population,ESs have been deteriorated over time.Ultimately,land use/land cover(LULC)changes have a profound impact ...Human well-being and livelihoods depend on natural ecosystem services(ESs).Following the increment of population,ESs have been deteriorated over time.Ultimately,land use/land cover(LULC)changes have a profound impact on the change of ecosystem.The primary goal of this study is to determine the impacts of LULC changes on ecosystem service values(ESVs)in the upper Gilgel Abbay watershed,Ethiopia.Changes in LULC types were studied using three Landsat images representing 1986,2003,and 2021.The Landsat images were classified using a supervised image classification technique in Earth Resources Data Analysis System(ERDAS)Imagine 2014.We classified ESs in this study into four categories(including provisioning,regulating,supporting,and cultural services)based on global ES classification scheme.The adjusted ESV coefficient benefit approach was employed to measure the impacts of LULC changes on ESVs.Five LULC types were identified in this study,including cultivated land,forest,shrubland,grassland,and water body.The result revealed that the area of cultivated land accounted for 64.50%,71.50%,and 61.50%of the total area in 1986,2003,and 2021,respectively.The percentage of the total area covered by forest was 9.50%,5.90%,and 14.80%in 1986,2003,and 2021,respectively.Result revealed that the total ESV decreased from 7.42×10^(7) to 6.44×10^(7) USD between 1986 and 2003.This is due to the expansion of cultivated land at the expense of forest and shrubland.However,the total ESV increased from 6.44×10^(7) to 7.76×10^(7) USD during 2003-2021,because of the increment of forest and shrubland.The expansion of cultivated land and the reductions of forest and shrubland reduced most individual ESs during 1986-2003.Nevertheless,the increase in forest and shrubland at the expense of cultivated land enhanced many ESs during 2003-2021.Therefore,the findings suggest that appropriate land use practices should be scaled-up to sustainably maintain ESs.展开更多
Lirispirolides A−L(1−12),twelve novel sesquiterpene-monoterpene heterodimers featuring distinctive carbon skeletons,were isolated from the branches and leaves of Chinese tulip tree[Liriodendron chinense(L.chinense)],a...Lirispirolides A−L(1−12),twelve novel sesquiterpene-monoterpene heterodimers featuring distinctive carbon skeletons,were isolated from the branches and leaves of Chinese tulip tree[Liriodendron chinense(L.chinense)],a rare medicinal and ornamental plant endemic to China.The structural elucidation was accomplished through comprehensive spectroscopic analyses,quantum-chemical calculations,and X-ray crystallography.These heterodimers exhibit a characteristic 2-oxaspiro[4.5]decan-1-one structural motif,biosynthetically formed through intermolecular[4+2]-cycloaddition between a germacrane-type sesquiterpene and an ocimene-type monoterpene.The majority of the isolated compounds demonstrated significant anti-neuroinflammatory effects in lipopolysaccharide(LPS)-induced BV-2 microglial cells by reducing the production of pro-inflammatory mediators,specifically tumor necrosis factor-α(TNF-α)and nitric oxide(NO).Further investigation revealed that the lirispirolides’inhibition of NO release correlated with decreased messenger ribonucleic acid(mRNA)expression of inducible NO synthase(iNOS).展开更多
Isoflavones which mainly distributed in leguminous plants have plenty of health benefits.Isoflavone synthase(IFS)is a membrane-associated cytochrome P450 enzyme(CYP450)which carries out the unique aryl-ring migration ...Isoflavones which mainly distributed in leguminous plants have plenty of health benefits.Isoflavone synthase(IFS)is a membrane-associated cytochrome P450 enzyme(CYP450)which carries out the unique aryl-ring migration and hydroxylation.So far,few crystal structures of plant P450s have been obtained.We determined the crystal structure of IFS from Medicago truncatula at 1.9 by MAD method using a selenomethionine substituted crystal and conducted molecular docking and mutagenesis study.The structure of IFS complexed with imidazole exhibits the helix Iα-loop-helix Iβmotif which corresponds to helix I of other P 450s.Compared with structures of common P450s,IFS/imidazole structure contains an extra domain,i.e.,theγ-domain.The structure reveals a homodimer in which theγ-domain of one molecule interacts with theβ-domain of another.The plane of heme group makes an angle of approximately 40°with the helix Iα-loop-helix Iβmotif.Molecular docking combined with mutagenesis study suggested that Trp-128 and Asp-300 might play important roles in substrate binding and recognition.Phe-301,Ser-303 and Gly-305 from the helix Iα-loop-helix Iβmotif may play important roles in the aryl-ring migration.These novel structural features reveal insights into the unique reaction mechanism of IFS and provide a basis for engineering IFS in leguminous crops for health purpose.展开更多
Melanomas are aggressive cancers,with a high rate of metastatic disease.Cutaneous(CM)and uveal(UM)melanomas are intrinsically different diseases,and most cell death inducers effective for CM do not function for UM.Thi...Melanomas are aggressive cancers,with a high rate of metastatic disease.Cutaneous(CM)and uveal(UM)melanomas are intrinsically different diseases,and most cell death inducers effective for CM do not function for UM.This is primarily due to the fact the eye is an immunologically privileged organ,and it fails to achieve the efficacy of immune checkpoint inhibitors(ICIs)comparable to that for CM.However,approaches utilizing specific melanomaassociated antigens are being developed for metastatic forms of CM and UM.The most promising to date are gp100 and tyrosinase related protein 1(TYRP1),primarily for the design of targeting chimeric molecules and for autologous T-/NK-cell products with a chimeric antigen receptor.The difference in the mutational profile of apoptosis-related genes in CM and UM also makes counterproductive the use of the same drugs re-activators of the intrinsic pathway of apoptosis.Therefore,the discovery of novel pathways of regulated cell death such as ferroptosis and cuproptosis may help in the development of new drugs for melanomas resistant to already available inducers of regulated cell death.Here we consistently discuss the latest advances in the therapy of melanomas,and above all-UM,which is classified as an orphan disease.展开更多
Changes in food production,often driven by distant demand,have a significant influence on sustainable man agement and use of land and water,and are in turn a driving factor of biodiversity change.While the connection ...Changes in food production,often driven by distant demand,have a significant influence on sustainable man agement and use of land and water,and are in turn a driving factor of biodiversity change.While the connection between land use and demand through value chains is increasingly understood,there is no comprehensive concep tualisation of this relationship.To address this gap,we propose a conceptual framework and use it as a basis for a systematic review to characterise value-chain connection and explore its influence on land-use and-cover change.Our search in June 2022 onWeb of Science and Scopus yielded 198 documents,describing studies completed after the year 2000 that provide information on both value-chain connection and land-use or-cover change.In total,we used 531 distinct cases to assess how frequently particular types of land-use or-cover change and value-chain connections co-occurred,and synthesized findings on their relations.Our findings confirm that 1)market inte gration is associated with intensification;2)land managers with environmental standards more frequently adopt environmentally friendly practices;3)physical and value-chain distances to consumers play a crucial role,with shorter distances associated with environmentally friendly practices and global chains linked to intensification and expansion.Incorporating these characteristics in existing theories of land-system change,would significantly advance understanding of land managers’decision-making,ultimately guiding more environmentally responsible production systems and contributing to global sustainability goals.展开更多
Herbivorous ungulates are vital elements of forest ecosystems,yet their impact on tree regeneration and forest dynamics is challenging to assess.Despite their significant influence,few studies measure browsing pressur...Herbivorous ungulates are vital elements of forest ecosystems,yet their impact on tree regeneration and forest dynamics is challenging to assess.Despite their significant influence,few studies measure browsing pressure independently of precise ungulate population data.This study aimed to determine the regeneration mechanisms of palatable tree species in natural forest ecosystems by measuring the forage abundance from young trees of focal species and estimating the browsing pressure exerted by ungulates.We analyzed an extensive dataset of 2,838 tree saplings in two national parks in Poland to examine relationships between variables using a zero-intercept linear regression,and multiple linear regression models,and performed parametric and nonparametric tests.We found that the browsing intensity index(BI)is a good predictor of browsing pressure.Both total abundance and twig dry mass loss due to ungulate browsing were more pronounced in shorter saplings,with these effects decreasing as sapling height increased.Picea abies was the most abundant browse source in the Tatra National Park(TNP),whereas Fagus sylvatica dominated in the Roztocze National Park(RNP).Acer pseudoplatanus and Sorbus aucuparia experienced significantly higher browsing pressure in the TNP,whereas Carpinus betulus was more heavily browsed than other species in the RNP.The increase in browse abundance rapidly reduced ungulate browsing pressure on highly palatable tree species.We conclude that despite the high browsing pressure on the palatable species,the contribution of browse from focal species helps to mitigate this pressure and supports their regeneration in the forest canopy.Therefore,this finding provides valuable insights for managing and conserving tree species vulnerable to ungulate browsing in natural forest ecosystems.In addition,the method we used in this study is novel to estimate browsing pressure and assess the recruitment potential of vulnerable tree species;hence,it can be applied in large-scale studies with similar scenarios.展开更多
文摘It is necessary to understand all the prerequisites, which result in gas hydrate formation for safe design and control of a variety of processes in petroleum industry. Thermodynamic hydrate inhibitors (THIs) are normally used to preclude gas hydrate formation by shifting hydrate stability region to lower temperatures and higher pressures. Sometimes, it is difficult to avoid hydrate formation and hydrates will form anyway. In this situation, kinetic hydrate inhibitors (KHIs) can be used to postpone formation of gas hydrates by retarding hydrate nucleation and growth rate. In this study, two kinetic parameters including natural gas hydrate formation induction time and the rate of gas consumption were experimentally investigated in the presence of monoethylene glycol (MEG), L-tyrosine, and polyvinylpyrrolidone (PVP) at various concentrations in aqueous solutions. Since hydrate formation is a stochastic phenomenon, the repeatability of each kinetic parameter was evaluated several times and the average values for the hydrate formation induction times and the rates of gas consumption are reported. The results indicate that from the view point of hydrate formation induction time, 2 wt% PVP and 20 wt% MEG aqueous solutions have the highest values and are the best choices. It is also interpreted from the results that from the view point of the rate of gas consumption, 20 wt% MEG aqueous solution yields the lowest value and is the best choice. Finally, it is concluded that the combination of PVP and MEG in an aqueous solution has a simultaneous synergistic impact on natural gas hydrate formation induction time and the rate of gas consumption. Furthermore, a semi-empirical model based on chemical kinetic theory is applied to evaluate the hydrate formation induction time data. A good agreement between the experimental and calculated hydrate formation induction time data is observed.
基金supported by NSFC (Grant No. 41202100)the National Science and Technology Major Projects(Grant No. 2008ZX05007-003)
文摘In order to distinguish the source and migration direction of natural gas by geochemical characteristics of butane,the components and carbon isotopes of natural gas from major hydrocarbonbearing basins in China were analyzed.The results showed that：（1） Oil-type gas has i-C 4 /n-C 4 0.8,δ 13 C butane -28‰,δ 13 C i-butane -27‰,δ 13 C n-butane -28.5‰,whereas coal-type gas has i-C 4 /n-C 4 0.8,δ 13 C butane -25.5‰,δ 13 C i-butane -24‰,δ 13 C n-butane -26‰.（2） When δ 13 C i-butane-δ 13 C n-butane is greater than 0,the maturity of oil-type gas is generally more than 2.4% and that of coal-type gas is greater than 1.4%,whereas when the difference is less than 0,the maturity of oil-type gas is generally less than 1.1% and that of coal-type gas is less than 0.8%.（3） When natural gas migrates through dense cap rocks,the value of i-C 4 /n-C 4 increases,whereas when it migrates laterally along a reservoir,the value of i-C 4 /n-C 4 decreases.（4） Sapropelic transition zone gas with composition and carbon isotopic signatures similar to those of oil-type gas in the low thermal evolution stage is found to have a relatively high butane content.（5） The values of i-C 4 /n-C 4 and δ 13 C n-butane δ 13 C i-butane of gas which has suffered biological degradation are significantly higher than those obtained from thermogenic and bio-thermocatalytic transition zone gas.Thus,natural gas of different genetic types can be recognized through component analysis and carbon isotopic signatures of butane,the natural gas maturity can be estimated from the difference in carbon isotopic content between isobutane and n-butane,and the migration direction of natural gas can be determined from i-C 4 /n-C 4 ratios and transport conditions,which can also be used to thermogenic and bio-thermocatalytic transition zone gas.
文摘Environmental sociology and the sociology of natural resources are two key subdisciplines of the sociological study on the interactions between nature and human society.Previous discussion on the relationships of these two fields has largely focused on their distinctions and synthesis in western(particularly American) academia.Environmental sociology emerged as an important sociological subdiscipline in China in the early 1990s and is under vigorous disciplinary construction at present.By contrast,the sociology of natural resources is still a novel term for most Chinese researchers.This article provides a systematic review of recent literature on the relationships between environmental and natural resource sociologies,which should provide important implications for the further development of environmental sociology in China.
基金supported by the Natural Science Foundation of Jiangsu Province(No.BK20201332).
文摘Influenza virus poses a significant threat to global public health,causing serious repercussions on human life and social well-being.Over the past decades,various antiviral drugs targeting either the virus itself or its host were identified.However,the emergence of drug-resistant influenza virus strains has posed a critical challenge to the effectiveness of these existing anti-influenza agents .Consequently,there is an urgent need to develop novel molecules with new chemical frameworks.Macrocyclic natural products serve as a crucial resource for validating targets and discovering lead compounds.However,the number of naturlly crring macrocyclic natural products is limited due to inherent biosynthetic pathways,which restricts the development of macrocyclic drugs.In contrast,artificially synthesized pseudonatural products show enhanced availability and greater structural diversity,while possessing similar biological functions[5]and have attracted significant interest from medicinal chemists.Hence,it is valuable to develop effective synthetic methods to expedite the discovery of macrocyclic lead compounds.
文摘Natural Products always exhibit more intellectual bioactivities and atom economy,and it’s also an important source of innovative drugs.Prof.SUN Han-Dong,Academician of Chinese Academy of Sciences from Kunming Institute of Botany,has made outstanding contributions to natural product chemistry,andsetagoodexamplefor ouryounggeneration.Onthe occasion ofProfSun’s 80th birthday,I’d like to express my deep respect to him,and wish Prof.SUN a happy birthday and good health.
文摘Alfalfa (Medicago sativa L.) is an important forage and conservation crop in North America but occurrences of naturalized alfalfa in rangelands are rare. A naturalized population of yellow-flowered alfalfa in mixed-grass prairie on the Grand River National Grassland in South Dakota has potential agricultural value for the region. Despite this value, the distribution pattern of this alfalfa among and within native plant communities in the northern Great Plains is unknown. Field studies were conducted from 2003 through 2006 along topographic positions at two sites where yellow-flowered alfalfa was naturalized to evaluate the relationships of yellow-flowered alfalfa on biomass production, cover, species diversity, and alfalfa seedbank distribution characteristics. High yellow-flowered alfalfa cover (>50%) was associated with increased total biomass and occurred exclusively in swales and toeslopes that had silty loam soils. However, species diversity and non-alfalfa biomass were reduced when yellow-flowered alfalfa cover was high. Yellow-flowered alfalfa cover was lower and species richness was higher on backslopes and shoulder areas where sandy loam soils were present. A strong positive linear association existed between yellow-flowered alfalfa cover and alfalfa seedbank density (r values ranged from 0.76 to 0.82, P < 0.0001). Greater than 99% of the seeds were viable but germination rate was only 4%, indicating a high percentage of hard seed in this alfalfa population. Naturalized yellow-flowered alfalfa was a dominant component of a stable, low diversity plant community composed of mainly introduced species in rich soils of swales/toeslopes that contributed to forage production and quality in mixed-grass prairie in the northern Great Plains.
文摘Caspian Gas into Balkans over medium to long term becames Albanian case on June 2013 when TAP route was selected. After Albanian National Territory Council approved TAP AG＇s Compound Development Permit, the project should start Construction Phase 1. Existing gas pipeline connections of Albania within the European network via TAP, is highly estimated by energy authorities in both technical and regulating aspects. New pipelines are projected to be build in order to meet local energy consume and seasonal fluctuations, as well as needs of Kosovo and FYROM. Some of important points： determination on the capacity sector building for a due Albanian Gas Market Model, supply options on the future gasification, alternatives of opening underground gas storages in the salt domes of Dumre region and extending pipelines to neighboring countries. By assistance of the Secretariat of Energy Community, MEI starts drafting the new gas law to meet Third Energy Package. TAP project, IAP project, Albania-Kosovo Pipeline, an LNG plant and terminals coastal construction, can contribute on the diversification of gas supply. Underground Gas Storage potentials are geologic solution target, considering the Upper Miocene depleted sandstone gas fields of Divjaka, as well as the Dumre evaporitic deposits diapir of the Upper Triassic.
文摘The problem of solid waste landfills on Caspian Sea coastlines is one of the current concerns of the Iranian environmental authorities. Physical and environmental constraints as well as shortcomings in present municipal solid waste management are the main factors for environmental pollution and natural resources destruction in this geographical region. In order to reduce the above problems, this study has been carried out on the basis of a comparative assessment of the existing condition of landfill sites in natural ecosystems. In this study, 48 cities of the region have been investigated. All of them are located in Gilan and Mazandaran provinces. Total daily waste production in the study area is about 1209 tons that are dumped in open spaces and/or in aquatic and terrestrial ecosystems. Surveying of 53 physical, adaptability and constraint parameters as well as hygiene and environmental parameters in the landfills, based on “Monavari-94 Method” indicate that the main problem in all of them is a high groundwater table. In 42% of landfills, the groundwater level is between from 0.5 to 2 meters. This phenomenon may cause severe risks due to the infiltration of leachate into potable groundwater. Indeed, the results of the study show that 87.5% of the landfills are located in areas with unacceptable conditions. In spite of geographical and environmental problems and constraints and as a final alternative in this respect, the need for sanitary and technical solid waste management is the main need of the study areas.
文摘Conjugate effects heat and mass transfer on free convection flow across an isothermal sphere immersed in a viscous incompressible fluid in the presence of species concentration with radiation heat loss has been investigated in this paper. The governing boundary layer equations are first transformed into a non-dimensional form and the resulting nonlinear systems of partial differential equations are then solved numerically using Finite—difference method with Keller-box Scheme. We have focused our attention on the evaluation velocity profiles, temperature profiles and species concentration profiles of the fluid as well as the local skin friction coefficient, local heat transfer rate and local species concentration transfer rate for a wide range of radiation parameter Rd, Schmidt number Sc and Prandlt number Pr.
文摘Inflammatory bowel disease(IBD)is a chronic inflammatory illness of the intes-tine.While the mechanism underlying the pathogenesis of IBD is not fully under-stood,it is believed that a complex combination of host immunological response,environmental exposure,particularly the gut microbiota,and genetic suscept-ibility represents the major determinants.The gut virome is a group of viruses found in great frequency in the gastrointestinal tract of humans.The gut virome varies greatly among individuals and is influenced by factors including lifestyle,diet,health and disease conditions,geography,and urbanization.The majority of research has focused on the significance of gut bacteria in the progression of IBD,although viral populations represent an important component of the microbiome.We conducted this review to highlight the viral communities in the gut and their expected roles in the etiopathogenesis of IBD regarding published research to date.
文摘In this study, an occupancy factor model was developed and used to calculate the average time spent for outdoor and indoor activities along the coastline of the Erongo region of Namibia. A closed ended questionnaire was developed and administered to 800 respondents who visited the coastline for leisure, occupational and other activities. The mean time allocated for leisure activities ranges from 13.00 to 1.00 h, occupational mean time between 10.18 to 9.06 h and the values of other activities range from 16.66 to 11.00 h. The average computed time spent outdoor was found to be 11.46 h and indoor calculated to be 12.54 h. This shows an outdoor factor of 0.48 and indoor factor of 0.52 respectively. From the results obtained, the value of the absorbed dose rate ranged from 93.27 to 105.95 nGy·h<sup>ǃ</sup> and the annual effective dose rate ranged from 121.01 to 176.61 μSv·y<sup>ǃ</sup> (UNSCEAR factor) and 292.60 to 413.63 μSv·y<sup>ǃ</sup> (present factor). The values obtained for annual effective dose are higher than the acceptable limit. However, from this study, we can conclude that the use of the UNSCEAR outdoor factor in the coastline will lead to underestimation of effective dose by 24% based on the present factor.
文摘Road traffic flow forecasting provides critical information for the operational management of road mobility challenges, and models are used to generate the forecast. This paper uses a random process to present a novel traffic modelling framework for aggregate traffic on urban roads. The main idea is that road traffic flow is random, even for the recurrent flow, such as rush hour traffic, which is predisposed to congestion. Therefore, the structure of the aggregate traffic flow model for urban roads should correlate well with the essential variables of the observed random dynamics of the traffic flow phenomena. The novelty of this paper is the developed framework, based on the Poisson process, the kinematics of urban road traffic flow, and the intermediate modelling approach, which were combined to formulate the model. Empirical data from an urban road in Ghana was used to explore the model’s fidelity. The results show that the distribution from the model correlates well with that of the empirical traffic, providing a strong validation of the new framework and instilling confidence in its potential for significantly improved forecasts and, hence, a more hopeful outlook for real-world traffic management.
文摘Aims:Reed(Phragmites australis)is a plant species with a seasonal reproductive cycle;it has a very high biomass in U Minh Thuong National Park,in Vietnam.This study aims to evaluate fresh and dry biomass of the reed and the production of biochar from the plants.The biochar is then used as a bio-organic fertilizer for watermelon cultivation in agriculture.Methods:To achieve these objectives the following experiments were conducted(1)investtigating the fresh and dry biomass of reeds producing biochar using local methods;(2)adsorption with pig urine and chemical fertilizers(nitrogen,phosphorus and potash)to examine the uptake of chemical components into the water environment;(3)mixing biochar with inorganic mineral fertilizers and peat to creat inorganic fertilizer–biochar formulas,followed by an analysis of the chemical compositions of the mixtures;(4)using various biochar-based fertilizers to grow watermelon with local varieties.Results:The results show that reeds produce very high for biomass biochar fertilizer production.Reed biochar can adsorb components of pig urine,such as ammonium,nitrate,nitrogen and phosphorus along with inorganic substances such as nitrogen,phosphorus and potash.Therefore this study proposes the use of this biochar for watermelon cultivation and environment treatment in polluted regions.Conclusions:Biomass and biochar of reed are very high.The biochar can adsorb nitrogen,phosphorus and potash fertilizers.Additionally,biochar can be mixed with peat and inorganic mineral fertilizers for to watermelon cultivation in Mekong Delta.Implications of the research:Forest fires in U Minh Thuong National Park,caused by reed vegetation,occur annually and result in damage to property and human livelihoods.This research not only exploits renewable raw materials but also helps control the risk of forest fires.Originality/Valeu:This study aims to provide methods for controlling forest fires by producing biochar of from reed(Phragmites australis)U Minh Thuong National Park Vietnam.This species thrives and produces a large biomass during the rainy season,supllying dry material that contributes to the intensity of forest fires in the dry season in Vietnam.
文摘Human well-being and livelihoods depend on natural ecosystem services(ESs).Following the increment of population,ESs have been deteriorated over time.Ultimately,land use/land cover(LULC)changes have a profound impact on the change of ecosystem.The primary goal of this study is to determine the impacts of LULC changes on ecosystem service values(ESVs)in the upper Gilgel Abbay watershed,Ethiopia.Changes in LULC types were studied using three Landsat images representing 1986,2003,and 2021.The Landsat images were classified using a supervised image classification technique in Earth Resources Data Analysis System(ERDAS)Imagine 2014.We classified ESs in this study into four categories(including provisioning,regulating,supporting,and cultural services)based on global ES classification scheme.The adjusted ESV coefficient benefit approach was employed to measure the impacts of LULC changes on ESVs.Five LULC types were identified in this study,including cultivated land,forest,shrubland,grassland,and water body.The result revealed that the area of cultivated land accounted for 64.50%,71.50%,and 61.50%of the total area in 1986,2003,and 2021,respectively.The percentage of the total area covered by forest was 9.50%,5.90%,and 14.80%in 1986,2003,and 2021,respectively.Result revealed that the total ESV decreased from 7.42×10^(7) to 6.44×10^(7) USD between 1986 and 2003.This is due to the expansion of cultivated land at the expense of forest and shrubland.However,the total ESV increased from 6.44×10^(7) to 7.76×10^(7) USD during 2003-2021,because of the increment of forest and shrubland.The expansion of cultivated land and the reductions of forest and shrubland reduced most individual ESs during 1986-2003.Nevertheless,the increase in forest and shrubland at the expense of cultivated land enhanced many ESs during 2003-2021.Therefore,the findings suggest that appropriate land use practices should be scaled-up to sustainably maintain ESs.
基金supported by the National Natural Science Foundation of China(Nos.82373752 and 21937002)the Science and Technology Commission of Shanghai Municipality(No.22ZR1414400).
文摘Lirispirolides A−L(1−12),twelve novel sesquiterpene-monoterpene heterodimers featuring distinctive carbon skeletons,were isolated from the branches and leaves of Chinese tulip tree[Liriodendron chinense(L.chinense)],a rare medicinal and ornamental plant endemic to China.The structural elucidation was accomplished through comprehensive spectroscopic analyses,quantum-chemical calculations,and X-ray crystallography.These heterodimers exhibit a characteristic 2-oxaspiro[4.5]decan-1-one structural motif,biosynthetically formed through intermolecular[4+2]-cycloaddition between a germacrane-type sesquiterpene and an ocimene-type monoterpene.The majority of the isolated compounds demonstrated significant anti-neuroinflammatory effects in lipopolysaccharide(LPS)-induced BV-2 microglial cells by reducing the production of pro-inflammatory mediators,specifically tumor necrosis factor-α(TNF-α)and nitric oxide(NO).Further investigation revealed that the lirispirolides’inhibition of NO release correlated with decreased messenger ribonucleic acid(mRNA)expression of inducible NO synthase(iNOS).
文摘Isoflavones which mainly distributed in leguminous plants have plenty of health benefits.Isoflavone synthase(IFS)is a membrane-associated cytochrome P450 enzyme(CYP450)which carries out the unique aryl-ring migration and hydroxylation.So far,few crystal structures of plant P450s have been obtained.We determined the crystal structure of IFS from Medicago truncatula at 1.9 by MAD method using a selenomethionine substituted crystal and conducted molecular docking and mutagenesis study.The structure of IFS complexed with imidazole exhibits the helix Iα-loop-helix Iβmotif which corresponds to helix I of other P 450s.Compared with structures of common P450s,IFS/imidazole structure contains an extra domain,i.e.,theγ-domain.The structure reveals a homodimer in which theγ-domain of one molecule interacts with theβ-domain of another.The plane of heme group makes an angle of approximately 40°with the helix Iα-loop-helix Iβmotif.Molecular docking combined with mutagenesis study suggested that Trp-128 and Asp-300 might play important roles in substrate binding and recognition.Phe-301,Ser-303 and Gly-305 from the helix Iα-loop-helix Iβmotif may play important roles in the aryl-ring migration.These novel structural features reveal insights into the unique reaction mechanism of IFS and provide a basis for engineering IFS in leguminous crops for health purpose.
基金supported by the Russian Science Foundation,project no.23-14-00285。
文摘Melanomas are aggressive cancers,with a high rate of metastatic disease.Cutaneous(CM)and uveal(UM)melanomas are intrinsically different diseases,and most cell death inducers effective for CM do not function for UM.This is primarily due to the fact the eye is an immunologically privileged organ,and it fails to achieve the efficacy of immune checkpoint inhibitors(ICIs)comparable to that for CM.However,approaches utilizing specific melanomaassociated antigens are being developed for metastatic forms of CM and UM.The most promising to date are gp100 and tyrosinase related protein 1(TYRP1),primarily for the design of targeting chimeric molecules and for autologous T-/NK-cell products with a chimeric antigen receptor.The difference in the mutational profile of apoptosis-related genes in CM and UM also makes counterproductive the use of the same drugs re-activators of the intrinsic pathway of apoptosis.Therefore,the discovery of novel pathways of regulated cell death such as ferroptosis and cuproptosis may help in the development of new drugs for melanomas resistant to already available inducers of regulated cell death.Here we consistently discuss the latest advances in the therapy of melanomas,and above all-UM,which is classified as an orphan disease.
文摘Changes in food production,often driven by distant demand,have a significant influence on sustainable man agement and use of land and water,and are in turn a driving factor of biodiversity change.While the connection between land use and demand through value chains is increasingly understood,there is no comprehensive concep tualisation of this relationship.To address this gap,we propose a conceptual framework and use it as a basis for a systematic review to characterise value-chain connection and explore its influence on land-use and-cover change.Our search in June 2022 onWeb of Science and Scopus yielded 198 documents,describing studies completed after the year 2000 that provide information on both value-chain connection and land-use or-cover change.In total,we used 531 distinct cases to assess how frequently particular types of land-use or-cover change and value-chain connections co-occurred,and synthesized findings on their relations.Our findings confirm that 1)market inte gration is associated with intensification;2)land managers with environmental standards more frequently adopt environmentally friendly practices;3)physical and value-chain distances to consumers play a crucial role,with shorter distances associated with environmentally friendly practices and global chains linked to intensification and expansion.Incorporating these characteristics in existing theories of land-system change,would significantly advance understanding of land managers’decision-making,ultimately guiding more environmentally responsible production systems and contributing to global sustainability goals.
基金funded by Polish National Science Foundation(NCN)(grant No.2018/31/B/NZ8/02786,project title:“How do largescale disturbances influence the relationship between ungulate herbivory and natural regeneration in temperate forests?”)from the Ministry of Science and Higher Education of the Republic of Poland within the framework of statutory activities SUB/040011-D019/2020 of the Department of Forest Biodiversity,University of Agriculture in Krakow.
文摘Herbivorous ungulates are vital elements of forest ecosystems,yet their impact on tree regeneration and forest dynamics is challenging to assess.Despite their significant influence,few studies measure browsing pressure independently of precise ungulate population data.This study aimed to determine the regeneration mechanisms of palatable tree species in natural forest ecosystems by measuring the forage abundance from young trees of focal species and estimating the browsing pressure exerted by ungulates.We analyzed an extensive dataset of 2,838 tree saplings in two national parks in Poland to examine relationships between variables using a zero-intercept linear regression,and multiple linear regression models,and performed parametric and nonparametric tests.We found that the browsing intensity index(BI)is a good predictor of browsing pressure.Both total abundance and twig dry mass loss due to ungulate browsing were more pronounced in shorter saplings,with these effects decreasing as sapling height increased.Picea abies was the most abundant browse source in the Tatra National Park(TNP),whereas Fagus sylvatica dominated in the Roztocze National Park(RNP).Acer pseudoplatanus and Sorbus aucuparia experienced significantly higher browsing pressure in the TNP,whereas Carpinus betulus was more heavily browsed than other species in the RNP.The increase in browse abundance rapidly reduced ungulate browsing pressure on highly palatable tree species.We conclude that despite the high browsing pressure on the palatable species,the contribution of browse from focal species helps to mitigate this pressure and supports their regeneration in the forest canopy.Therefore,this finding provides valuable insights for managing and conserving tree species vulnerable to ungulate browsing in natural forest ecosystems.In addition,the method we used in this study is novel to estimate browsing pressure and assess the recruitment potential of vulnerable tree species;hence,it can be applied in large-scale studies with similar scenarios.
