Recent advances in additive manufacturing have enabled the construction of metallic lattice structures with tailored mechanical and functional properties.One potential application of metallic lattice struc-tures is in...Recent advances in additive manufacturing have enabled the construction of metallic lattice structures with tailored mechanical and functional properties.One potential application of metallic lattice struc-tures is in the impact load mitigation where an external kinetic energy is absorbed by the deformation/crushing of lattice cells.This has motivated a growing number of experimental and numerical studies,recently,on the crushing behavior of additively produced lattice structures.The present study overviews the dynamic and quasi-static crushing behavior of additively produced Ti64,316L,and AlSiMg alloy lattice structures.The first part of the study summarizes the main features of two most commonly used additive processing techniques for lattice structures,namely selective-laser-melt(SLM)and electro-beam-melt(EBM),along with a description of commonly observed process induced defects.In the second part,the deformation and strain rate sensitivities of the selected alloy lattices are outlined together with the most widely used dynamic test methods,followed by a part on the observed micro-structures of the SLM and EBM-processed Ti64,316L and AlSiMg alloys.Finally,the experimental and numerical studies on the quasi-static and dynamic compression behavior of the additively processed Ti64,316L,and AlSiMg alloy lattices are reviewed.The results of the experimental and numerical studies of the dynamic properties of various types of lattices,including graded,non-uniform strut size,hollow,non-uniform cell size,and bio-inspired,were tabulated together with the used dynamic testing methods.The dynamic tests have been noted to be mostly conducted in compression Split Hopkinson Pressure Bar(SHPB)or Taylor-and direct-impact tests using the SHPB set-up,in all of which relatively small-size test specimens were tested.The test specimen size effect on the compression behavior of the lattices was further emphasized.It has also been shown that the lattices of Ti64 and AlSiMg alloys are relatively brittle as compared with the lattices of 316L alloy.Finally,the challenges associated with modelling lattice structures were explained and the micro tension tests and multi-scale modeling techniques combining microstructural characteristics with macroscopic lattice dynamics were recommended to improve the accuracy of the numerical simulations of the dynamic compression deformations of metallic lattice structures.展开更多
The pear(Pyrus spp.)is well known for diverse flavors,textures,and global horticultural importance.However,the genetic diversity responsible for its extensive phenotypic variations remains largely unexplored.Here,we d...The pear(Pyrus spp.)is well known for diverse flavors,textures,and global horticultural importance.However,the genetic diversity responsible for its extensive phenotypic variations remains largely unexplored.Here,we de novo assembled and annotated the genomes of the maternal(PsbM)and paternal(PsbF)lines of the hybrid‘Yuluxiang'pear and constructed the pear pangenome of 1.15 Gb by combining these two genomes with five previously published pear genomes representing cultivated and wild germplasm.Using the constructed pangenome,we identified 21224 gene PAVs(Presence-absence variation)and 1158812 SNPs(Single Nucleotide Polymorphism)in the non-reference genome that were absent in the PsbM reference genome.Compared with SNP markers,PAV-based analysis provides additional insights into the pear population structure.In addition,some genes associated with pear fruit quality traits have differential occurrence frequencies and differential gene expression between Asian and European populations.Moreover,our analysis of the pear pangenome revealed a mutated SNP and an insertion in the promoter region of the gene PsbMGH3.1 potentially enhance sepal shedding in‘Xuehuali'which is vital for pear quality.PsbMGH3.1 may play a role in the IAA pathway,contributing to a distinct low-auxin phenotype observed in plants by heterologously overexpressing this gene.This research helps capture the genetic diversity of pear populations and provides genomic resources for accelerating breeding.展开更多
The objective of this paper is to present a new method for designing absorbing or non-reflective boundary conditions (ABC) or (NRBC), illustrated by the case study of the modelling of a solid body in water, specifical...The objective of this paper is to present a new method for designing absorbing or non-reflective boundary conditions (ABC) or (NRBC), illustrated by the case study of the modelling of a solid body in water, specifically the capillary gravity waves generated by its motion at the surface. The study analyses the flow of an inviscid, barotropic, and compressible fluid around the stationary solid body. The dynamic behaviour of the fluid is analysed using a two-dimensional coupled Neumann-Kelvin model extended with capillarity and inertia terms. For computational purposes, it is necessary to truncate the unbounded spatial domain with artificial boundaries and then introduce appropriate absorbing boundary conditions. The propagation of short wavelength waves in a convective fluid medium with significant differences in properties between the interior and the surface of the fluid presents a number of difficulties in the design of these conditions. The results are illustrated numerically and commented upon.展开更多
The Atlantic Meridional Overturning Circulation(AMOC)is a crucial component of the Earth’s climate system due to its fundamental role in heat distribution,carbon and oxygen transport,and the weather.Other climate com...The Atlantic Meridional Overturning Circulation(AMOC)is a crucial component of the Earth’s climate system due to its fundamental role in heat distribution,carbon and oxygen transport,and the weather.Other climate components,such as the atmosphere and sea ice,influence the AMOC.Evaluating the physical mechanisms of those interactions is paramount to increasing knowledge about AMOC’s functioning.In this study,the authors used outputs from the Community Earth System Model version 2 and observational data to investigate changes in theAMOC and the associated physical processes.Two DECK experiments were evaluated:piControl and 1pctCO_(2),with an annual increase of 1%of atmospheric CO_(2).The analysis revealed a significant decrease in the AMOC,associated with changes in mixed layer depth and buoyancy in high latitudes of the North Atlantic,resulting in the shutdown of deep convection and potentially affecting the formation of North Atlantic Deep Water and Antarctic Bottom Water.A vital aspect observed in this study is the association between increased runoff and reduced water evaporation,giving rise to a positive feedback process.Consequently,the rates of freshwater spreading have intensified during this period,which could lead to an accelerated disruption of the AMOC beyond the projections of existing models.展开更多
Mixing efficiency in two-phase gas–liquid agitated vessel is one of the important challenges in the industrial processes.Computational fluid dynamics technique(CFD)was used to investigate the effect of four different...Mixing efficiency in two-phase gas–liquid agitated vessel is one of the important challenges in the industrial processes.Computational fluid dynamics technique(CFD)was used to investigate the effect of four different pitched blade impellers,including 15°,30°,45°and 60°,on the mixing quality of gas–liquid agitated vessel.The multiphase flow behavior was modeled by Eulerian–Eulerian multiphase approach,and RNG k-εwas used to model the turbulence.The CFD results showed that a strong global vortex plays the main role on the mixing quality of the gas phase in the vessel.Based on the standard deviation criterion,it was observed that the axial distribution of the gas phase in the 30°impeller is about 55%better than the others.In addition,the results showed that the 30°impeller has a uniform radial distribution over the other impellers and the maximum gas phase holdup in the vessel.Investigation of the power consumption of the impellers showed that the 30°impeller has the highest power consumption among the other pitched blade impellers.Also,examine the effect of same power condition for pitched blade impellers showed that the 30°impeller has the best mixing quality in this condition.展开更多
Long term hepatitis B virus (HBV) infection is a major risk factor in pathogenesis of chronic liver diseases,including hepatocellular carcinoma (HCC). The HBV encod-ed proteins,hepatitis B virus X protein and preS,app...Long term hepatitis B virus (HBV) infection is a major risk factor in pathogenesis of chronic liver diseases,including hepatocellular carcinoma (HCC). The HBV encod-ed proteins,hepatitis B virus X protein and preS,appear to contribute importantly to the pathogenesis of HCC. Both are associated with oxidative stress,which can damage cellular molecules like lipids,proteins,and DNA during chronic infection. Chronic alcohol use is another important factor that contributes to oxidative stress in the liver. Previous studies reported that treatment with antioxidants,such as curcumin,silymarin,green tea,and vitamins C and E,can protect DNA from damage and regulate liver pathogenesis-related cascades by reducing reactive oxygen species. This review summarizes some of the relationships between oxidative stress and liver pathogenesis,focusing upon HBV and alcohol,and suggests antioxidant therapeutic approaches.展开更多
AIM:To investigate the role of hepatitis B virus X-protein(HBx)-induced reactive oxygen species(ROS)on liver carcinogenesis in HBx transgenic mice and HepG2-HBx cells.METHODS:Cell growth rate was analyzed,and through ...AIM:To investigate the role of hepatitis B virus X-protein(HBx)-induced reactive oxygen species(ROS)on liver carcinogenesis in HBx transgenic mice and HepG2-HBx cells.METHODS:Cell growth rate was analyzed,and through western blotting,mitogenic signaling was observed.Endogenous ROS from wild and HBx transgenic mice and HepG2-Mock and HBx cells were assayed by FACS-calibur.Identification of oxidized and reduced phosphatase and tensin homolog(PTEN)was analyzed through N-ethylmaleimide alkylation,nonreducing electrophoresis.RESULTS:We observed that the cell-proliferation-related phosphoinositide 3-kinase/Akt pathway is activated by HBx in vivo and in vitro.Increased ROS were detected by HBx.Tumor suppressor PTEN,via dephosphorylation of Akt,was oxidized and inactivated by increased ROS.Increased oxidized PTEN activated the mitogenic pathway through over-activated Akt.However,treatment with ROS scavenger N-acetyl cysteine can reverse PTEN to a reduced form.Endogenously produced ROS also stimulated HBx expression.CONCLUSION:HBx induced ROS promoted Akt pathways via oxidized inactive PTEN.HBx and ROS maintained a positive regulatory loop,which aggravated carcinogenesis.展开更多
Burgeoning growth of tall buildings in urban areas around the world is placing new demands on their performance under winds.This involves selection of the building form that minimizes wind loads and structural topolog...Burgeoning growth of tall buildings in urban areas around the world is placing new demands on their performance under winds.This involves selection of the building form that minimizes wind loads and structural topologies that efficiently transfer loads.Current practice is to search for optimal shapes,but this limits buildings with static or fixed form.Aerodynamic shape tailoring that consists of modifying the external form of the building has shown great promise in reducing wind loads and associated structural motions as reflected in the design of Taipei 101 and Burj Khalifa.In these buildings,corner modifications of the cross-section and tapering along the height are introduced.An appealing alternative is to design a building that can adapt its form to the changing complex wind environment in urban areas with clusters of tall buildings,i.e.,by implementing a dynamic facade.To leap beyond the static shape optimization,autonomous dynamic morphing of the building shape is advanced in this study,which is implemented through a cyber–physical system that fuses together sensing,computing,actuating,and engineering informatics.This approach will permit a building to intelligently morph its profile to minimize the source of dynamic wind load excitation,and holds the promise of revolutionizing tall buildings from conventional static to dynamic facades by taking advantage of the burgeoning advances in computational design.展开更多
Accurate inversion of land surface evapotranspiration （ET） in arid areas is of great significance for understanding global eco-hydrological process and exploring the spatio-temporal variation and ecological response...Accurate inversion of land surface evapotranspiration （ET） in arid areas is of great significance for understanding global eco-hydrological process and exploring the spatio-temporal variation and ecological response of water resources. It is also important in the functional evaluation of regional water cycle and water balance, as well as the rational allocation and management of water resources. This study, based on model validation analysis at varied scales in fiwe Central Asian countries and China＇s Xinjiang, developed an appropriate approach for ET inversion in arid lands. The actual ET during growing seasons of the study area was defined, and the changes in water participating in evaporation in regional water cycle were then educed. The results show the simulation error of SEBS （Surface Energy Balance System） model under cloud amount consideration was 1.34% at 30-m spatial scale, 2.75% at 1-km spatial scale and 6,37% at 4-kin spatial scale. ET inversion for 1980-2007 applying SEBS model in the study area indicates： （1） the evaporation depth （May-September） by land types descends in the order of waters （660.24 ram） 〉 cultivated land （464.66 mm） 〉 woodland （388.44 mm） 〉 urbanized land （168.16 mm） 〉 grassland （160.48 mm） 〉 unused land （83.08 mm）; and （2） ET during the 2005 growing season in Xinjiang and Central Asia was 2,168.68x108 m3 （with an evaporation/precipitation ratio of 1.05） and 9,741.03x108 m3 （with an evaporation/precipitation ratio of 1.4）, respectively. The results unveiled the spatio-temporal variation rules of ET process in arid areas, providing a reference for further research on the water cycle and water balance in similar arid regions.展开更多
In response to limited availability of soil resources in basal root zone, plant extends its roots into nearby resource-rich zones to fulfill essential resource demands for survival and reproduction. This root prolifer...In response to limited availability of soil resources in basal root zone, plant extends its roots into nearby resource-rich zones to fulfill essential resource demands for survival and reproduction. This root proliferation into that enriched zones occupied by other plants constitutes interplant overlapping rooting zones and thereby the overlapping depletion zones, causing reduction in resource uptake by neighboring plants. By incorporating this mechanism into the classic resource competition model, we study interplant direct competition through their rooting system in an overlapping depletion zone. The model results indicate an extension of Tilman’s R* rule that has already been proved true when plants compete indirectly through their effect on shared resources. The results reveal that plant’s direct competitive ability (i.e., the ability to occupy an overlapping depletion zone by excluding others) can be characterized by its R*-value, where a best competitor having lowest R*-value excludes others from an overlapping zone and occupies the zone by depleting the resource level to the lowest as in its non-overlapping depletion zone. By analyzing the model, we find a suite of traits that confers R* variation among directly competing plants. This suite of traits would be a useful proxy measure for R* that do not necessarily require to establish equilibrium field monoculture—a requirement for R* measurement in the field.展开更多
Seasonal shifts play an important role in soil microbial community composition. This study examined the hypothesis that soil microbial community structure would vary with seasonal shifts in the Wuyi Mountains in South...Seasonal shifts play an important role in soil microbial community composition. This study examined the hypothesis that soil microbial community structure would vary with seasonal shifts in the Wuyi Mountains in Southeast China, and that two representative tree species （Castanopisi carlesii and Cunninghamia lanceolata） may have different soil microbial community composition. Phospholipids fatty acid analysis （PLFA） of seasonal shifts and was used to assess the effect vegetation types on soil microbial community structure. A total of 22 different PLFAs were identified from all the soil samples. The bacterial PLFAs accounted for 62.37% of the total PLFAs, followed by fungi （28.94%）, and the minimum was actinomycetes （6.41%）. Overall, the level of PLFAs in C. carlesii soil was greater than those in C. lanceolata soil, and significant differences were observed in some seasons. The amounts of total, bacteria, actinomycic and fungal PLFAs significantly changed with the seasons and followed a sequence order （summer 〉 autumn 〉 spring 〉 winter）. The bacteria/fungi PLFAs and G （＋）/G （-） PLFAs of two vegetation types also changed with the seasons and the ratios in summer and autumn were higher than those in spring and winter. The correlation analysis of microbial PLFAs and soil physicochemical properties showed that the total, bacteria, fungal, actinomycic, G （＋） and G （-） PLFAs were significantly positive correlation with TOC, TN, TP, TK and moisture content. We concluded that the seasonal shifts and vegetation types affect soil microbial community composition by changing the soil physicochemical properties.展开更多
Acetylcholinesterase(AChE) plays an important role in Alzheimer's disease(AD). The excessive activity of AChE causes various neuronal problems, particularly dementia and neuronal cell deaths. Generally, antiAChE d...Acetylcholinesterase(AChE) plays an important role in Alzheimer's disease(AD). The excessive activity of AChE causes various neuronal problems, particularly dementia and neuronal cell deaths. Generally, antiAChE drugs induce some serious neuronal side effects in humans. Therefore, this study sought to identify alternative drug molecules from natural products with fewer side effects than those of conventional drugs for treating AD. To achieve this, we developed computational methods for predicting drug and target binding affinities using the Schrodinger suite. The target and ligand molecules were retrieved from established databases. The target enzyme has 539 amino acid residues in its sequence alignment. Ligand molecules of 20 bioactive molecules were obtained from different kinds of plants, after which we performed critical analyses such as molecular docking; molecular dynamic(MD) simulations; and absorption, distribution, metabolism, and excretion(ADME) analysis. In the docking studies, the natural compound rutin showed a superior docking score of à 12.335 with a good binding energy value ofà73.313 kcal/mol. Based on these findings, rutin and the target complex was used to perform MD simulations to analyze rutin stability at 30 ns. In conclusion, our study demonstrates that rutin is a superior drug candidate for AD. Therefore, we propose that this molecule is worth further investigation using in vitro studies.展开更多
Ecosystem stays far from thermodynamic equilibrium. Through the interactions among biotic and abiotic components, and encompassing physical environments, ecosystem forms a dissipative struc- ture that allows it to dis...Ecosystem stays far from thermodynamic equilibrium. Through the interactions among biotic and abiotic components, and encompassing physical environments, ecosystem forms a dissipative struc- ture that allows it to dissipate energy continuously and thereby remains functional over time. Biotic regulation of energy and material fluxes in and out of the ecosystem allows it to maintain a homeostatic state which corresponds to a self-organized state emerged in a non-equilibrium thermodynamic system. While the associated self-organizational processes approach to homeostatic state, entropy （a measure of irre- versibility） degrades and dissipation of energy increases. We propose here that at a homeostatic state of ecosystem, biodiversity which includes both phenotypic and functional diversity, attains optimal values. As long as biodiversity remains within its optimal range, the corresponding homeostatic state is maintained. However, while embedded environmental conditions fluctuate along the gradient of accelerating changes, phenotypic diversity and functional diversity contribute inversely to the associated self-organizing proc- esses. Furthermore, an increase or decrease in biodiversity outside of its optimal range makes the eco- system vulnerable to transition into a different state.展开更多
Spatial organization of multiple plant species that appears as a non-random distribution of vegetative patches is one of the mostly observed spatial patterns in arid ecosystems. Yet understanding of ecological process...Spatial organization of multiple plant species that appears as a non-random distribution of vegetative patches is one of the mostly observed spatial patterns in arid ecosystems. Yet understanding of ecological processes allowing this spatial pattern to emerge through interspecific interactions is still lacking. With a proposed conceptual model involving interspecific trade-offs between species competitive ability and colonization ability, we have argued that within patch abundance dynamics regulated by the mechanisms of competition are strongly influenced by the between patches colonization dynamics that are maintained via this trade-offs and it holds a positive, intraspecific occupancy-abundance relationship, in which increased patch occupancy increases species density within inhabiting patches. In a constant environment, while local abundance dynamics approach toward a stable equilibrium point, a fixed spatial arrangement of species can be retained through this coupled dynamics. However, in fluctuating environments where existence of such stable equilibriums is highly uncertain, it may involve continuous transitions from one community state to another as species re-organized themselves over space through the rapid changes in local species abundances. While some of the inhabiting patches are destroyed exogenously or endogenously, or species responses to increasing environmental fluctuations vary increasingly with time, discontinuous transitions into an abrupt, irreversible state of the community dynamics may occur, as with this effect the inherent positive relationship between occupancy and abundance of species is no longer maintained.展开更多
基金the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No 101034425 for the project titled A2M2TECHThe Scientific and Technological Research Council of Türkiye (TUBITAK) with grant No 120C158 for the same A2M2TECH project under the TUBITAK's 2236/B program
文摘Recent advances in additive manufacturing have enabled the construction of metallic lattice structures with tailored mechanical and functional properties.One potential application of metallic lattice struc-tures is in the impact load mitigation where an external kinetic energy is absorbed by the deformation/crushing of lattice cells.This has motivated a growing number of experimental and numerical studies,recently,on the crushing behavior of additively produced lattice structures.The present study overviews the dynamic and quasi-static crushing behavior of additively produced Ti64,316L,and AlSiMg alloy lattice structures.The first part of the study summarizes the main features of two most commonly used additive processing techniques for lattice structures,namely selective-laser-melt(SLM)and electro-beam-melt(EBM),along with a description of commonly observed process induced defects.In the second part,the deformation and strain rate sensitivities of the selected alloy lattices are outlined together with the most widely used dynamic test methods,followed by a part on the observed micro-structures of the SLM and EBM-processed Ti64,316L and AlSiMg alloys.Finally,the experimental and numerical studies on the quasi-static and dynamic compression behavior of the additively processed Ti64,316L,and AlSiMg alloy lattices are reviewed.The results of the experimental and numerical studies of the dynamic properties of various types of lattices,including graded,non-uniform strut size,hollow,non-uniform cell size,and bio-inspired,were tabulated together with the used dynamic testing methods.The dynamic tests have been noted to be mostly conducted in compression Split Hopkinson Pressure Bar(SHPB)or Taylor-and direct-impact tests using the SHPB set-up,in all of which relatively small-size test specimens were tested.The test specimen size effect on the compression behavior of the lattices was further emphasized.It has also been shown that the lattices of Ti64 and AlSiMg alloys are relatively brittle as compared with the lattices of 316L alloy.Finally,the challenges associated with modelling lattice structures were explained and the micro tension tests and multi-scale modeling techniques combining microstructural characteristics with macroscopic lattice dynamics were recommended to improve the accuracy of the numerical simulations of the dynamic compression deformations of metallic lattice structures.
基金supported by the National Natural Science Foundation of China(Grant No.32102364)the General Program of Shandong Natural Science Foundation(Grant No.ZR2022MC064)+3 种基金the Shanxi Province Postdoctoral Research Activity Fund(Grant No.K462101001)the Doctoral Research Initiation Fund of Shanxi Datong University(Grant No.2023-B-15)the Earmarked Fund for Modern Agro-industry Technology Research System(Grant No.2023CYJSTX07)the Shanxi Province Excellent Doctoral Work Award Project(Grant No.606-02010609)。
文摘The pear(Pyrus spp.)is well known for diverse flavors,textures,and global horticultural importance.However,the genetic diversity responsible for its extensive phenotypic variations remains largely unexplored.Here,we de novo assembled and annotated the genomes of the maternal(PsbM)and paternal(PsbF)lines of the hybrid‘Yuluxiang'pear and constructed the pear pangenome of 1.15 Gb by combining these two genomes with five previously published pear genomes representing cultivated and wild germplasm.Using the constructed pangenome,we identified 21224 gene PAVs(Presence-absence variation)and 1158812 SNPs(Single Nucleotide Polymorphism)in the non-reference genome that were absent in the PsbM reference genome.Compared with SNP markers,PAV-based analysis provides additional insights into the pear population structure.In addition,some genes associated with pear fruit quality traits have differential occurrence frequencies and differential gene expression between Asian and European populations.Moreover,our analysis of the pear pangenome revealed a mutated SNP and an insertion in the promoter region of the gene PsbMGH3.1 potentially enhance sepal shedding in‘Xuehuali'which is vital for pear quality.PsbMGH3.1 may play a role in the IAA pathway,contributing to a distinct low-auxin phenotype observed in plants by heterologously overexpressing this gene.This research helps capture the genetic diversity of pear populations and provides genomic resources for accelerating breeding.
文摘The objective of this paper is to present a new method for designing absorbing or non-reflective boundary conditions (ABC) or (NRBC), illustrated by the case study of the modelling of a solid body in water, specifically the capillary gravity waves generated by its motion at the surface. The study analyses the flow of an inviscid, barotropic, and compressible fluid around the stationary solid body. The dynamic behaviour of the fluid is analysed using a two-dimensional coupled Neumann-Kelvin model extended with capillarity and inertia terms. For computational purposes, it is necessary to truncate the unbounded spatial domain with artificial boundaries and then introduce appropriate absorbing boundary conditions. The propagation of short wavelength waves in a convective fluid medium with significant differences in properties between the interior and the surface of the fluid presents a number of difficulties in the design of these conditions. The results are illustrated numerically and commented upon.
基金This work was possible through the financing of PEC-20480 Project between Royal Dutch Shell(Shell)and the Laboratório de Métodos Computacionais em Engenharia(LAMCE)and through the doctoral fellowship funding by CNPq for Elisa Passos Case number 141819/2016-2the postdoctoral fellowship funding by FAPERJ E 10/2020-Edital Inteligência Artificial Case Number E-26/203.327/2022-Enrollment No.Scholarship 2015.08297.7 for Lívia Sancho.
文摘The Atlantic Meridional Overturning Circulation(AMOC)is a crucial component of the Earth’s climate system due to its fundamental role in heat distribution,carbon and oxygen transport,and the weather.Other climate components,such as the atmosphere and sea ice,influence the AMOC.Evaluating the physical mechanisms of those interactions is paramount to increasing knowledge about AMOC’s functioning.In this study,the authors used outputs from the Community Earth System Model version 2 and observational data to investigate changes in theAMOC and the associated physical processes.Two DECK experiments were evaluated:piControl and 1pctCO_(2),with an annual increase of 1%of atmospheric CO_(2).The analysis revealed a significant decrease in the AMOC,associated with changes in mixed layer depth and buoyancy in high latitudes of the North Atlantic,resulting in the shutdown of deep convection and potentially affecting the formation of North Atlantic Deep Water and Antarctic Bottom Water.A vital aspect observed in this study is the association between increased runoff and reduced water evaporation,giving rise to a positive feedback process.Consequently,the rates of freshwater spreading have intensified during this period,which could lead to an accelerated disruption of the AMOC beyond the projections of existing models.
基金Semnan University for the financial support of this research(grant number 845)。
文摘Mixing efficiency in two-phase gas–liquid agitated vessel is one of the important challenges in the industrial processes.Computational fluid dynamics technique(CFD)was used to investigate the effect of four different pitched blade impellers,including 15°,30°,45°and 60°,on the mixing quality of gas–liquid agitated vessel.The multiphase flow behavior was modeled by Eulerian–Eulerian multiphase approach,and RNG k-εwas used to model the turbulence.The CFD results showed that a strong global vortex plays the main role on the mixing quality of the gas phase in the vessel.Based on the standard deviation criterion,it was observed that the axial distribution of the gas phase in the 30°impeller is about 55%better than the others.In addition,the results showed that the 30°impeller has a uniform radial distribution over the other impellers and the maximum gas phase holdup in the vessel.Investigation of the power consumption of the impellers showed that the 30°impeller has the highest power consumption among the other pitched blade impellers.Also,examine the effect of same power condition for pitched blade impellers showed that the 30°impeller has the best mixing quality in this condition.
基金Supported by The 21st Century Frontier Program in the Functional Human Genome Project, No. HGM0200934the International Collaboration Program of Science and Technology, No. FGM0600914the Ministry of Education, Science and Technology, and the KRIBB Research Initiative Program Grant, No. KGM3320911, South Korea
文摘Long term hepatitis B virus (HBV) infection is a major risk factor in pathogenesis of chronic liver diseases,including hepatocellular carcinoma (HCC). The HBV encod-ed proteins,hepatitis B virus X protein and preS,appear to contribute importantly to the pathogenesis of HCC. Both are associated with oxidative stress,which can damage cellular molecules like lipids,proteins,and DNA during chronic infection. Chronic alcohol use is another important factor that contributes to oxidative stress in the liver. Previous studies reported that treatment with antioxidants,such as curcumin,silymarin,green tea,and vitamins C and E,can protect DNA from damage and regulate liver pathogenesis-related cascades by reducing reactive oxygen species. This review summarizes some of the relationships between oxidative stress and liver pathogenesis,focusing upon HBV and alcohol,and suggests antioxidant therapeutic approaches.
基金Supported by The 21st century Frontier Program in the Functional Human Genome Project,No.HGM0200934the International Collaboration Program of Science and Technology,No. FGM0600914+1 种基金the Research Program for New Drug Target Discovery Grant from the Ministry of Education,Science & Technology,No.NBM3300711the KRIBB Research Initiative Program Grant,No.KGM3320911
文摘AIM:To investigate the role of hepatitis B virus X-protein(HBx)-induced reactive oxygen species(ROS)on liver carcinogenesis in HBx transgenic mice and HepG2-HBx cells.METHODS:Cell growth rate was analyzed,and through western blotting,mitogenic signaling was observed.Endogenous ROS from wild and HBx transgenic mice and HepG2-Mock and HBx cells were assayed by FACS-calibur.Identification of oxidized and reduced phosphatase and tensin homolog(PTEN)was analyzed through N-ethylmaleimide alkylation,nonreducing electrophoresis.RESULTS:We observed that the cell-proliferation-related phosphoinositide 3-kinase/Akt pathway is activated by HBx in vivo and in vitro.Increased ROS were detected by HBx.Tumor suppressor PTEN,via dephosphorylation of Akt,was oxidized and inactivated by increased ROS.Increased oxidized PTEN activated the mitogenic pathway through over-activated Akt.However,treatment with ROS scavenger N-acetyl cysteine can reverse PTEN to a reduced form.Endogenously produced ROS also stimulated HBx expression.CONCLUSION:HBx induced ROS promoted Akt pathways via oxidized inactive PTEN.HBx and ROS maintained a positive regulatory loop,which aggravated carcinogenesis.
基金the US National Science Foundation(CMMI-1562244 and CMMI-1612843)。
文摘Burgeoning growth of tall buildings in urban areas around the world is placing new demands on their performance under winds.This involves selection of the building form that minimizes wind loads and structural topologies that efficiently transfer loads.Current practice is to search for optimal shapes,but this limits buildings with static or fixed form.Aerodynamic shape tailoring that consists of modifying the external form of the building has shown great promise in reducing wind loads and associated structural motions as reflected in the design of Taipei 101 and Burj Khalifa.In these buildings,corner modifications of the cross-section and tapering along the height are introduced.An appealing alternative is to design a building that can adapt its form to the changing complex wind environment in urban areas with clusters of tall buildings,i.e.,by implementing a dynamic facade.To leap beyond the static shape optimization,autonomous dynamic morphing of the building shape is advanced in this study,which is implemented through a cyber–physical system that fuses together sensing,computing,actuating,and engineering informatics.This approach will permit a building to intelligently morph its profile to minimize the source of dynamic wind load excitation,and holds the promise of revolutionizing tall buildings from conventional static to dynamic facades by taking advantage of the burgeoning advances in computational design.
基金supported by the National Natural Science Foundation of China (40730633 and 40571030)
文摘Accurate inversion of land surface evapotranspiration （ET） in arid areas is of great significance for understanding global eco-hydrological process and exploring the spatio-temporal variation and ecological response of water resources. It is also important in the functional evaluation of regional water cycle and water balance, as well as the rational allocation and management of water resources. This study, based on model validation analysis at varied scales in fiwe Central Asian countries and China＇s Xinjiang, developed an appropriate approach for ET inversion in arid lands. The actual ET during growing seasons of the study area was defined, and the changes in water participating in evaporation in regional water cycle were then educed. The results show the simulation error of SEBS （Surface Energy Balance System） model under cloud amount consideration was 1.34% at 30-m spatial scale, 2.75% at 1-km spatial scale and 6,37% at 4-kin spatial scale. ET inversion for 1980-2007 applying SEBS model in the study area indicates： （1） the evaporation depth （May-September） by land types descends in the order of waters （660.24 ram） 〉 cultivated land （464.66 mm） 〉 woodland （388.44 mm） 〉 urbanized land （168.16 mm） 〉 grassland （160.48 mm） 〉 unused land （83.08 mm）; and （2） ET during the 2005 growing season in Xinjiang and Central Asia was 2,168.68x108 m3 （with an evaporation/precipitation ratio of 1.05） and 9,741.03x108 m3 （with an evaporation/precipitation ratio of 1.4）, respectively. The results unveiled the spatio-temporal variation rules of ET process in arid areas, providing a reference for further research on the water cycle and water balance in similar arid regions.
基金supported by the U.S.National Science Foundation’s Biocomplexity Program (DEB-0421530)LTER Program (DEB0620482)
文摘In response to limited availability of soil resources in basal root zone, plant extends its roots into nearby resource-rich zones to fulfill essential resource demands for survival and reproduction. This root proliferation into that enriched zones occupied by other plants constitutes interplant overlapping rooting zones and thereby the overlapping depletion zones, causing reduction in resource uptake by neighboring plants. By incorporating this mechanism into the classic resource competition model, we study interplant direct competition through their rooting system in an overlapping depletion zone. The model results indicate an extension of Tilman’s R* rule that has already been proved true when plants compete indirectly through their effect on shared resources. The results reveal that plant’s direct competitive ability (i.e., the ability to occupy an overlapping depletion zone by excluding others) can be characterized by its R*-value, where a best competitor having lowest R*-value excludes others from an overlapping zone and occupies the zone by depleting the resource level to the lowest as in its non-overlapping depletion zone. By analyzing the model, we find a suite of traits that confers R* variation among directly competing plants. This suite of traits would be a useful proxy measure for R* that do not necessarily require to establish equilibrium field monoculture—a requirement for R* measurement in the field.
基金supported by the National Natural Science Foundation of China (Grant No.31500443)Fujian Province Department of Education Foundation (Grant No.JA15178)
文摘Seasonal shifts play an important role in soil microbial community composition. This study examined the hypothesis that soil microbial community structure would vary with seasonal shifts in the Wuyi Mountains in Southeast China, and that two representative tree species （Castanopisi carlesii and Cunninghamia lanceolata） may have different soil microbial community composition. Phospholipids fatty acid analysis （PLFA） of seasonal shifts and was used to assess the effect vegetation types on soil microbial community structure. A total of 22 different PLFAs were identified from all the soil samples. The bacterial PLFAs accounted for 62.37% of the total PLFAs, followed by fungi （28.94%）, and the minimum was actinomycetes （6.41%）. Overall, the level of PLFAs in C. carlesii soil was greater than those in C. lanceolata soil, and significant differences were observed in some seasons. The amounts of total, bacteria, actinomycic and fungal PLFAs significantly changed with the seasons and followed a sequence order （summer 〉 autumn 〉 spring 〉 winter）. The bacteria/fungi PLFAs and G （＋）/G （-） PLFAs of two vegetation types also changed with the seasons and the ratios in summer and autumn were higher than those in spring and winter. The correlation analysis of microbial PLFAs and soil physicochemical properties showed that the total, bacteria, fungal, actinomycic, G （＋） and G （-） PLFAs were significantly positive correlation with TOC, TN, TP, TK and moisture content. We concluded that the seasonal shifts and vegetation types affect soil microbial community composition by changing the soil physicochemical properties.
基金DST-SERB (SB/YS/LS-109/2014) for providing financial assistance for this project
文摘Acetylcholinesterase(AChE) plays an important role in Alzheimer's disease(AD). The excessive activity of AChE causes various neuronal problems, particularly dementia and neuronal cell deaths. Generally, antiAChE drugs induce some serious neuronal side effects in humans. Therefore, this study sought to identify alternative drug molecules from natural products with fewer side effects than those of conventional drugs for treating AD. To achieve this, we developed computational methods for predicting drug and target binding affinities using the Schrodinger suite. The target and ligand molecules were retrieved from established databases. The target enzyme has 539 amino acid residues in its sequence alignment. Ligand molecules of 20 bioactive molecules were obtained from different kinds of plants, after which we performed critical analyses such as molecular docking; molecular dynamic(MD) simulations; and absorption, distribution, metabolism, and excretion(ADME) analysis. In the docking studies, the natural compound rutin showed a superior docking score of à 12.335 with a good binding energy value ofà73.313 kcal/mol. Based on these findings, rutin and the target complex was used to perform MD simulations to analyze rutin stability at 30 ns. In conclusion, our study demonstrates that rutin is a superior drug candidate for AD. Therefore, we propose that this molecule is worth further investigation using in vitro studies.
基金supported by the U.S. National Science Foundation's Biocomplexity Program (DEB-0421530)Long-Term Ecological Research Program (Sevilleta LTER,DEB-0620482)
文摘Ecosystem stays far from thermodynamic equilibrium. Through the interactions among biotic and abiotic components, and encompassing physical environments, ecosystem forms a dissipative struc- ture that allows it to dissipate energy continuously and thereby remains functional over time. Biotic regulation of energy and material fluxes in and out of the ecosystem allows it to maintain a homeostatic state which corresponds to a self-organized state emerged in a non-equilibrium thermodynamic system. While the associated self-organizational processes approach to homeostatic state, entropy （a measure of irre- versibility） degrades and dissipation of energy increases. We propose here that at a homeostatic state of ecosystem, biodiversity which includes both phenotypic and functional diversity, attains optimal values. As long as biodiversity remains within its optimal range, the corresponding homeostatic state is maintained. However, while embedded environmental conditions fluctuate along the gradient of accelerating changes, phenotypic diversity and functional diversity contribute inversely to the associated self-organizing proc- esses. Furthermore, an increase or decrease in biodiversity outside of its optimal range makes the eco- system vulnerable to transition into a different state.
基金supported by the U.S. National Science Foundation’s Biocom-plexity Program (DEB-0421530)Long-Term Ecological Research Program (Sevilleta LTER, DEB-0217774 and 0620482)University of California Agricultural Experiment Station
文摘Spatial organization of multiple plant species that appears as a non-random distribution of vegetative patches is one of the mostly observed spatial patterns in arid ecosystems. Yet understanding of ecological processes allowing this spatial pattern to emerge through interspecific interactions is still lacking. With a proposed conceptual model involving interspecific trade-offs between species competitive ability and colonization ability, we have argued that within patch abundance dynamics regulated by the mechanisms of competition are strongly influenced by the between patches colonization dynamics that are maintained via this trade-offs and it holds a positive, intraspecific occupancy-abundance relationship, in which increased patch occupancy increases species density within inhabiting patches. In a constant environment, while local abundance dynamics approach toward a stable equilibrium point, a fixed spatial arrangement of species can be retained through this coupled dynamics. However, in fluctuating environments where existence of such stable equilibriums is highly uncertain, it may involve continuous transitions from one community state to another as species re-organized themselves over space through the rapid changes in local species abundances. While some of the inhabiting patches are destroyed exogenously or endogenously, or species responses to increasing environmental fluctuations vary increasingly with time, discontinuous transitions into an abrupt, irreversible state of the community dynamics may occur, as with this effect the inherent positive relationship between occupancy and abundance of species is no longer maintained.
