This study presents a facile and rapid method for synthesizing novel Layered Double Hydroxide(LDH)nanoflakes,exploring their application as a photocatalyst,and investigating the influence of condensed phosphates'g...This study presents a facile and rapid method for synthesizing novel Layered Double Hydroxide(LDH)nanoflakes,exploring their application as a photocatalyst,and investigating the influence of condensed phosphates'geometric linearity on their photocatalytic properties.Herein,the Mg O film,obtained by plasma electrolysis of AZ31 Mg alloys,was modified by growing an LDH film,which was further functionalized using cyclic sodium hexametaphosphate(CP)and linear sodium tripolyphosphate(LP).CP acted as an enhancer for flake spacing within the LDH structure,while LP changed flake dispersion and orientation.Consequently,CP@LDH demonstrated exceptional efficiency in heterogeneous photocatalysis,effectively degrading organic dyes like Methylene blue(MB),Congo red(CR),and Methyl orange(MO).The unique cyclic structure of CP likely enhances surface reactions and improves the catalyst's interaction with dye molecules.Furthermore,the condensed phosphate structure contributes to a higher surface area and reactivity in CP@LDH,leading to its superior photocatalytic performance compared to LP@LDH.Specifically,LP@LDH demonstrated notable degradation efficiencies of 93.02%,92.89%,and 88.81%for MB,MO,and CR respectively,over a 40 min duration.The highest degradation efficiencies were observed in the case of the CP@LDH sample,reporting 99.99%for MB,98.88%for CR,and 99.70%for MO.This underscores the potential of CP@LDH as a highly effective photocatalyst for organic dye degradation,offering promising prospects for environmental remediation and water detoxification applications.展开更多
Free cholesterol has been considered to be a critical risk factor of nonalcoholic fatty liver disease(NAFLD).It remains unknown whether dietary intake of condensed tannins(CTs)have distinguishable effects to alleviate...Free cholesterol has been considered to be a critical risk factor of nonalcoholic fatty liver disease(NAFLD).It remains unknown whether dietary intake of condensed tannins(CTs)have distinguishable effects to alleviate liver damage caused by a high cholesterol diet.Male C57BL/6 mice were fed a high cholesterol diet for 6 weeks,and given CTs treatment at a dosage of 200 mg/(kg·day)at the same time.The results indicated that compared with mice fed a normal diet,a high cholesterol diet group resulted in significant weight loss,dysregulation of lipid metabolism in blood and liver,and oxidative stress in the liver,but CTs treatment dramatically reversed these negative effects.Hematoxylin and eosin(H&E)staining and frozen section observation manifested that CTs treatment could effectively reduce the deposition of liver cholesterol and tissue necrosis caused by high cholesterol intake.CTs alleviated liver injury mainly by regulating the expression of related genes in cholesterol metabolism pathway and AMPK phosphorylation.Our results confirmed that CTs have remarkable cholesterol lowering and anti-liver injury effects in vivo.展开更多
Tannin was extracted from different subspecies of Acacia nilotica,Acacia nilotica nilotica(Ann),Acacia nilotica tomentosa(Ant)and Acacia nilotica adansonii(Ana).The aim was to elucidate their structure and evaluate th...Tannin was extracted from different subspecies of Acacia nilotica,Acacia nilotica nilotica(Ann),Acacia nilotica tomentosa(Ant)and Acacia nilotica adansonii(Ana).The aim was to elucidate their structure and evaluate their reactivity as bioadhesives in the wood industry.The extracts were prepared by hot water extraction(90°C tem-perature).Their gel time with paraformaldehyde was used atfirst to compare their reactivity.The tannin contents and the percentage of total polyphenolic materials in different solutions of the extracts spray dried powder were determined by the hide powder method.Concentrated solutions(47%)were tested by both MALDI ToF,13CNMR.The thermomechanical analysis(TMA)was performed to evaluate their modulus of elasticity(MOE)at different pHs.The gel times of all the three tannin extracts showed that their reactivity and it was com-parable to other known procyanidin/prodelphinidin tannin extract types.Ana,Ann and Ant showed highest per-cent of total polyphenolic materials at 70%,64%,and 57%,respectively.The 13CNMR spectra showed that the three subspecies of condensed tannins were mainly constituted of procyanidins(PC)and prodelphinidins(PD)in slightly different ratios.Ann(56.5%PC and 43.4%PD),Ant(57%PC and 43%PD)and Ana(58%PC and 42%PD).MALDI–TOF spectra showed the presence offlavonoid monomers,and oligomers some of which linked to short carbohydrates monomers or dimers.TMA revealed that the three types of tannins had high MOE at their initial pH(5).展开更多
Some proteins perform their biological functions by changing their material states through liquid-liquid phase separation.Upon phase separation,the protein condenses into a concentrated liquid phase and sometimes into...Some proteins perform their biological functions by changing their material states through liquid-liquid phase separation.Upon phase separation,the protein condenses into a concentrated liquid phase and sometimes into a gel phase,changing its dynamic properties and intermolecular interactions,thereby regulating cellular functions.Although the biological significance of this phenomenon has been widely recognized by researchers,there is still a lack of a comprehensive understanding of the structural and dynamic properties of the protein in the condensed phase.In this phase,molecules usually contain domains with varied dynamic properties and undergo intermediate exchanges.Magic angle spinning(MAS)solid-state NMR(SSNMR)experiments are very powerful in studying rigid protein polymers such as amyloid.The incorporation of solution-like experiments into SSNMR and the development of J-coupling based MAS SSNMR techniques extend its ability to study partially mobile segments of proteins in a condensed liquid or gel phase which are not visible by solution NMR or dipolar-coupling based SSNMR.Therefore,it has been applied in studying protein condensation and has provided very important information that is hard to obtain by other techniques.展开更多
In frequent tree pattern mining, the number of frequent subtrees generated is often too large. To tackle this problem, the concept of condensed frequent subtree base is proposed. The base consists of the maximal frequ...In frequent tree pattern mining, the number of frequent subtrees generated is often too large. To tackle this problem, the concept of condensed frequent subtree base is proposed. The base consists of the maximal frequent subtrees for a series of support thresholds. It is a subset of frequent subtrees, and is used to approximate the support of arbitrary frequent subtrees with guaranteed maximal error bound. In addition, an algorithm is developed to mine such a condensed subtree base in a database of labeled rooted ordered trees. The algorithm adopts the way of fight-most extension to generate systematically all frequent rooted ordered subtrees. Several techniques are proposed to prune the branches that do not correspond to the maximal frequent subtrees. Heuristic techniques are used to arrange the order of computation so that relatively expensive computation is avoided as much as possible. Experimental results show that the size of the base is less than 10% of that of the complete set, and the algorithm outperforms the previous algorithms.展开更多
On the basis of the two geological factors rock structure and ground stress environment,a visco elastic plastic model is established to analyze the rock stability of dam foundation and dam abutment during excavation...On the basis of the two geological factors rock structure and ground stress environment,a visco elastic plastic model is established to analyze the rock stability of dam foundation and dam abutment during excavation by a kind of FE condensed method.Rock mechanics is applied in analysing the dynamic process of displacements,stresses,yielding destruction of construction base level,soft interface of dam foundation.Results of the FE analysis indicate that theories and methods in this paper are reasonable and reliable.展开更多
Sodium pyrophosphate (pyro-P, Na4P2OT), sodium tripolyphosphate (tripoly-P, Na3P3O10), and sodium hexametaphosphate (meta-P, (NaPO3)6) were selected as the model compounds of condensed phosphate to investigate...Sodium pyrophosphate (pyro-P, Na4P2OT), sodium tripolyphosphate (tripoly-P, Na3P3O10), and sodium hexametaphosphate (meta-P, (NaPO3)6) were selected as the model compounds of condensed phosphate to investigate the adsorption behavior of condensed phosphate on aluminum hydroxide. The adsorption was found to be endothermic and divisible into two stages: (1) fast adsorption within 1 h; and (2) slow adsorption between 1 and 24 h. The modified Freundlich model simulated the fast adsorption stage well; the slow adsorption stage was described well by the first-order kinetics. The activation energies of pyro-P, tripoly-P, and meta-P adsorption on aluminum hydroxide were determined to be 20.2, 22.8 and 10.9 kJ/mol P adsorbed, respectively, in the fast adsorption stage and to be 66.3, 53.5 and 72.5 kJ/mol P adsorbed, respectively, in the slow adsorption stage. The adsorption increased the negative charge of the aluminum hydroxide surface. Transmission electron microscopy and energy dispersive X-ray analysis analyses provided evidence that the adsorption was not uniform on the surface and that the small crystals contributed more to the fast adsorption than the normal sites did. The results from X-ray fluorescence spectrometry and X-ray photoelectron spectroscopy tests also revealed the uneven adsorption of condensed phosphate as a function of the penetration depth. More condensed phosphates were adsorbed on the outer surface of aluminum hydroxide than in its inner parts.展开更多
The static flux chamber method was applied to study natural emissions of methane to the atmosphere in the Luntai fault region of Yakela Condensed Oil/Gas Field in the Tarim Basin, Xinjiang Municipality, northwestern C...The static flux chamber method was applied to study natural emissions of methane to the atmosphere in the Luntai fault region of Yakela Condensed Oil/Gas Field in the Tarim Basin, Xinjiang Municipality, northwestern China. Using an online method, which couples together a gas chromatography/high-temperature conversion/isotope ratio mass spectrometry (GC/C/MS), 13^C/12^C ratios of methane in flux chambers were measured and showed that methane gases are liable to migrate from deep oil/gas reservoirs to the surface through fault regions and that a part of the migrated methane, which remains unoxidized can be emitted into the atmosphere. Methane emission rates were found to be highest in the mornings, lowest in the afternoons and then increase gradually in the evenings. Methane emission rates varied dramatically in different locations in the fault region. The highest methane emission rate was 10.96 mg/m^2·d, the lowest 4.38 mg/m^2, and the average 7.55 mg/ m^2·d. The 13^C/12^C ratios of the methane in the flux chambers became heavier as the enclosed methane concentrations increased gradually, which reveals that methane released from the fault region might come from thermogenic methane of the deep condensed oil/gas reservoir.展开更多
A static flux chamber method was applied to study natural emissions of methane into the atmosphere in the Yakela condensed oil/gas field in Talimu Basin, Xinjiang, China. Using an online method, which couples a gas ch...A static flux chamber method was applied to study natural emissions of methane into the atmosphere in the Yakela condensed oil/gas field in Talimu Basin, Xinjiang, China. Using an online method, which couples a gas chromatography/high-temperature conversion/isotope ratio mass spectrometry (GC/C/MS) together, the 13C/12C ratios of methane in the flux chambers were measured. The results demonstrated that methane gases were liable to migrate from deep oil/gas reservoir to the surface through microseepage and p...展开更多
As a kind of low-cost and readily available industrial byproduct, ethylene tar (ET) was for the first time utilized for the preparation of heat-resistant condensed polynuclear aromatic resin (COPNAR). The basic pr...As a kind of low-cost and readily available industrial byproduct, ethylene tar (ET) was for the first time utilized for the preparation of heat-resistant condensed polynuclear aromatic resin (COPNAR). The basic properties of ET and the resulted COPNAR were characterized by FT-IR, IH-NMR, TGA and elemental analysis. The test results showed that ET with high aromatic content (〉50%) was suitable for the synthesis of COPNAR with superior heat resistance. The average molecular structure of ET was obtained by means of the improved Brown-Ladner method, and the reaction mechanism was considered as an acid-catalyzed positive ion-typed polymerization. Our findings have provided a new route to develop ET into technology-added heat-resistant resins.展开更多
A new type of Galerkin finite element for first-order initial-value problems(IVPs)is proposed.Both the trial and test functions employ the same m-degreed polynomials.The adjoint equation is used to eliminate one degre...A new type of Galerkin finite element for first-order initial-value problems(IVPs)is proposed.Both the trial and test functions employ the same m-degreed polynomials.The adjoint equation is used to eliminate one degree of freedom(DOF)from the test function,and then the so-called condensed test function and its consequent condensed Galerkin element are constructed.It is mathematically proved and numerically verified that the condensed element produces the super-convergent nodal solutions of O(h^(2m+2)),which is equivalent to the order of accuracy by the conventional element of degree m+1.Some related properties are addressed,and typical numerical examples of both linear and nonlinear IVPs of both a single equation and a system of equations are presented to show the validity and effectiveness of the proposed element.展开更多
Aluminum(Al) particles are commonly added to energetic materials including propellants,explosives and pyrotechnics to increase the overall energy density of the composite,but aluminum agglomeration on the combustion s...Aluminum(Al) particles are commonly added to energetic materials including propellants,explosives and pyrotechnics to increase the overall energy density of the composite,but aluminum agglomeration on the combustion surface may lower the combustion efficiency of propellants,resulting in a loss in twophase flow.Therefore,it is necessary to understand the agglomeration mechanism of aluminum particles on the combustion surface.In this paper,a high-pressure sealed combustion chamber is constructed,and high-speed camera is used to capture the whole process of aluminum accumulation,aggregation and agglomeration on the combustion surface,and the secondary agglomeration process near the combustion surface.The microscopic morphology and chemical composition of the condensed combustion products(CCPs) are then studied by using scanning electron microscopy coupled with energy dispersive(SEM-EDS) method.Results show that there are three main types of condensed combustion products:small smoke oxide particles oxidized by aluminum vapor,usually less than 1 μm;typical agglomerates formed by the combustion of aluminum agglomerates;carbonized agglomerates that are widely distributed,usually formed by irregular movements of aluminum agglomerates.The particle size of condensed combustion products is measured by laser particle size meter.As the pressure increases from 0.5 MPa to 1.0 MPa in nitrogen,the mass average particle size of aluminum agglomerates decreases by 49.7%.As the ambient gas is changed from 0.5 MPa nitrogen to 0.5 MPa air,the mass average particle size of aluminum agglomerates decreases by 67.3%.Results show that as the ambient pressure increases,the higher oxygen content can improve combustion efficiency and reduce the average agglomeration size of aluminum particles.展开更多
Lead has caused serious environmental pollution due to its toxicity, accumulation in food chains and persistence in nature. In this paper, removal of lead from aqueous solutions is investigated using a novel gel adsor...Lead has caused serious environmental pollution due to its toxicity, accumulation in food chains and persistence in nature. In this paper, removal of lead from aqueous solutions is investigated using a novel gel adsorbent synthesized from natural condensed tannin. The novel adsorbent performs in aqueous solutions as a weak base with valid basic groups of 1.2mmol·g-1 tannin gel particles and therefore results in the elevation of pH value of aqueous solutions. Even when initial pH is 3.6, final pH at equilibrium can climb up to 6.5 that is above the pH value for Pb(OH)2 precipitation formation and then lead can be removed from wastewater by this so-called surface precipitation. The adsorption isotherm can be expressed by the Langmuir equation and the maximum capacity for adsorption of Pb is up to 92 mg·g-1 (based on dry adsorbent) when initial pH value is 3.6. Hence, the adsorbent does offer favorable properties in lead removal with respect to its high adsorption capacity at low initial pH value, which is advantageous to lead removal from acidic wastewater. A model is put forward to describe the individual adsorption phenomenon of the tannin gel adsorbent.展开更多
The chaotic ratchet effect for Bos-Einstein condensed atoms in an optical lattice is investigated. By using the direct perturbation method we obtain the chaotic solution of the condensed system. Theoretical analysis r...The chaotic ratchet effect for Bos-Einstein condensed atoms in an optical lattice is investigated. By using the direct perturbation method we obtain the chaotic solution of the condensed system. Theoretical analysis reveals that the transport of the condensed atoms in the ratchet potential is a chaotic one, and corresponding numerical results agree well with the theoretical results.展开更多
According to the definitions of molecular connectivity and hyper-Wiener index, a novel set of hyper-Wiener indexes (Dn, ^mDn) were defined and named as condensed extended hyper-Wiener index, the potential usefulness...According to the definitions of molecular connectivity and hyper-Wiener index, a novel set of hyper-Wiener indexes (Dn, ^mDn) were defined and named as condensed extended hyper-Wiener index, the potential usefulness of which in QSAR/QSPR is evaluated by its correlation with a number of C3-C8 alkanes as well as by a favorable comparison with models based on molecular connectivity index and overall Wiener index.展开更多
In this paper n-hexane is chosen as typical volatile in condensed mode polymerization process, and the adsorption equilibrium of volatile in polyethylene particles is studied through experiments at different temperatu...In this paper n-hexane is chosen as typical volatile in condensed mode polymerization process, and the adsorption equilibrium of volatile in polyethylene particles is studied through experiments at different temperatures, pressures and particle diameters. It is found that more adsorbed quantity of volatile at equilibrium can be obtained with lower temperature, higher pressure and smaller particle diameter. Under polymerization conditions, the adsorbed quantity at equilibrium is more strongly affected by temperature than by pressure, and if the diameter distribution of particles is very wide the effect of diameter on the adsorbed quantity must be taken into consideration. With theoretical analyses a model is proposed for calculating the adsorbed quantity of volatile at equilibrium.展开更多
The study of wave propagation in finite/infinite media has many applications in geotechnical and structural earthquake engineering and has been a focus of research for the past few decades. This paper presents an anal...The study of wave propagation in finite/infinite media has many applications in geotechnical and structural earthquake engineering and has been a focus of research for the past few decades. This paper presents an analysis of 2D anti- plane problems (Love waves) and 2D in-plane problems (Rayleigh waves) in the frequency domain in media consisting of a near-field irregular and a far-field regular part. The near field part may contain structures and its boundaries with the far-field can be of any shape. In this study, the irregular boundaries of the near-field are treated as consistent boundaries, extending the concept of Lysmer's vertical consistent boundaries. The presented technique is called the Condensed Hyperelements Method (CHM). In this method, the irregular boundary is limited to a vertical boundary at each end that is a consistent boundary at the far-field side. Between the two ends, the medium is discretized with hyperelements. Using static condensation, the stiffness matrix of the far-field is derived for the nodes on the irregular boundary. Examples of the application of the CHM illustrate its excellent accuracy and efficiency.展开更多
Our understanding of how photons couple to different degrees of freedom in solids forms the bedrock of ultrafast physics and materials sciences.In this review,the emergent ultrafast dynamics in condensed matter at the...Our understanding of how photons couple to different degrees of freedom in solids forms the bedrock of ultrafast physics and materials sciences.In this review,the emergent ultrafast dynamics in condensed matter at the attosecond timescale have been intensively discussed.In particular,the focus is put on recent developments of attosecond dynamics of charge,exciton,and magnetism.New concepts and indispensable role of interactions among multiple degrees of freedom in solids are highlighted.Applications of attosecond electronic metrology and future prospects toward attosecond dynamics in condensed matter are further discussed.These pioneering studies promise future development of advanced attosecond science and technology such as attosecond lasers,laser medical engineering,and ultrafast electronic devices.展开更多
GCP and APP were used as flame retardants for poplar wood and larch wood,and their flame retardancy(OI), permeability (Surface electron spectroscopy), water-re pellency and corrosion toward nail evaluated. The results...GCP and APP were used as flame retardants for poplar wood and larch wood,and their flame retardancy(OI), permeability (Surface electron spectroscopy), water-re pellency and corrosion toward nail evaluated. The results showed that GCP is in advance of APP. From the thermal analysis and char composition analysis, it is concluded that GCP mainly functions in condensed phase.展开更多
基金the National Research Foundation of Korea(NRF)funded by the Korean Government(MSIT)(No.2022R1A2C1006743)。
文摘This study presents a facile and rapid method for synthesizing novel Layered Double Hydroxide(LDH)nanoflakes,exploring their application as a photocatalyst,and investigating the influence of condensed phosphates'geometric linearity on their photocatalytic properties.Herein,the Mg O film,obtained by plasma electrolysis of AZ31 Mg alloys,was modified by growing an LDH film,which was further functionalized using cyclic sodium hexametaphosphate(CP)and linear sodium tripolyphosphate(LP).CP acted as an enhancer for flake spacing within the LDH structure,while LP changed flake dispersion and orientation.Consequently,CP@LDH demonstrated exceptional efficiency in heterogeneous photocatalysis,effectively degrading organic dyes like Methylene blue(MB),Congo red(CR),and Methyl orange(MO).The unique cyclic structure of CP likely enhances surface reactions and improves the catalyst's interaction with dye molecules.Furthermore,the condensed phosphate structure contributes to a higher surface area and reactivity in CP@LDH,leading to its superior photocatalytic performance compared to LP@LDH.Specifically,LP@LDH demonstrated notable degradation efficiencies of 93.02%,92.89%,and 88.81%for MB,MO,and CR respectively,over a 40 min duration.The highest degradation efficiencies were observed in the case of the CP@LDH sample,reporting 99.99%for MB,98.88%for CR,and 99.70%for MO.This underscores the potential of CP@LDH as a highly effective photocatalyst for organic dye degradation,offering promising prospects for environmental remediation and water detoxification applications.
基金supported by the National Basic Research Program of China(2013CB127106)。
文摘Free cholesterol has been considered to be a critical risk factor of nonalcoholic fatty liver disease(NAFLD).It remains unknown whether dietary intake of condensed tannins(CTs)have distinguishable effects to alleviate liver damage caused by a high cholesterol diet.Male C57BL/6 mice were fed a high cholesterol diet for 6 weeks,and given CTs treatment at a dosage of 200 mg/(kg·day)at the same time.The results indicated that compared with mice fed a normal diet,a high cholesterol diet group resulted in significant weight loss,dysregulation of lipid metabolism in blood and liver,and oxidative stress in the liver,but CTs treatment dramatically reversed these negative effects.Hematoxylin and eosin(H&E)staining and frozen section observation manifested that CTs treatment could effectively reduce the deposition of liver cholesterol and tissue necrosis caused by high cholesterol intake.CTs alleviated liver injury mainly by regulating the expression of related genes in cholesterol metabolism pathway and AMPK phosphorylation.Our results confirmed that CTs have remarkable cholesterol lowering and anti-liver injury effects in vivo.
基金the fund provided by NAPATA program,jointly funded by France campus and the Ministry of Higher Education and Scientific research,SudanLab facilities provided by LERMAB which is supported by a grant of the French Agence Nationale de la Recherche(ANR)in the ambit of the laboratory of excellence(Labex)ARBRE is also aknowledged.
文摘Tannin was extracted from different subspecies of Acacia nilotica,Acacia nilotica nilotica(Ann),Acacia nilotica tomentosa(Ant)and Acacia nilotica adansonii(Ana).The aim was to elucidate their structure and evaluate their reactivity as bioadhesives in the wood industry.The extracts were prepared by hot water extraction(90°C tem-perature).Their gel time with paraformaldehyde was used atfirst to compare their reactivity.The tannin contents and the percentage of total polyphenolic materials in different solutions of the extracts spray dried powder were determined by the hide powder method.Concentrated solutions(47%)were tested by both MALDI ToF,13CNMR.The thermomechanical analysis(TMA)was performed to evaluate their modulus of elasticity(MOE)at different pHs.The gel times of all the three tannin extracts showed that their reactivity and it was com-parable to other known procyanidin/prodelphinidin tannin extract types.Ana,Ann and Ant showed highest per-cent of total polyphenolic materials at 70%,64%,and 57%,respectively.The 13CNMR spectra showed that the three subspecies of condensed tannins were mainly constituted of procyanidins(PC)and prodelphinidins(PD)in slightly different ratios.Ann(56.5%PC and 43.4%PD),Ant(57%PC and 43%PD)and Ana(58%PC and 42%PD).MALDI–TOF spectra showed the presence offlavonoid monomers,and oligomers some of which linked to short carbohydrates monomers or dimers.TMA revealed that the three types of tannins had high MOE at their initial pH(5).
基金supported by the National Natural Science Foundation of China(No.32171185,No.31770790)the National Key R&D Program of China(No.2017YFA0504804).
文摘Some proteins perform their biological functions by changing their material states through liquid-liquid phase separation.Upon phase separation,the protein condenses into a concentrated liquid phase and sometimes into a gel phase,changing its dynamic properties and intermolecular interactions,thereby regulating cellular functions.Although the biological significance of this phenomenon has been widely recognized by researchers,there is still a lack of a comprehensive understanding of the structural and dynamic properties of the protein in the condensed phase.In this phase,molecules usually contain domains with varied dynamic properties and undergo intermediate exchanges.Magic angle spinning(MAS)solid-state NMR(SSNMR)experiments are very powerful in studying rigid protein polymers such as amyloid.The incorporation of solution-like experiments into SSNMR and the development of J-coupling based MAS SSNMR techniques extend its ability to study partially mobile segments of proteins in a condensed liquid or gel phase which are not visible by solution NMR or dipolar-coupling based SSNMR.Therefore,it has been applied in studying protein condensation and has provided very important information that is hard to obtain by other techniques.
文摘In frequent tree pattern mining, the number of frequent subtrees generated is often too large. To tackle this problem, the concept of condensed frequent subtree base is proposed. The base consists of the maximal frequent subtrees for a series of support thresholds. It is a subset of frequent subtrees, and is used to approximate the support of arbitrary frequent subtrees with guaranteed maximal error bound. In addition, an algorithm is developed to mine such a condensed subtree base in a database of labeled rooted ordered trees. The algorithm adopts the way of fight-most extension to generate systematically all frequent rooted ordered subtrees. Several techniques are proposed to prune the branches that do not correspond to the maximal frequent subtrees. Heuristic techniques are used to arrange the order of computation so that relatively expensive computation is avoided as much as possible. Experimental results show that the size of the base is less than 10% of that of the complete set, and the algorithm outperforms the previous algorithms.
文摘On the basis of the two geological factors rock structure and ground stress environment,a visco elastic plastic model is established to analyze the rock stability of dam foundation and dam abutment during excavation by a kind of FE condensed method.Rock mechanics is applied in analysing the dynamic process of displacements,stresses,yielding destruction of construction base level,soft interface of dam foundation.Results of the FE analysis indicate that theories and methods in this paper are reasonable and reliable.
文摘Sodium pyrophosphate (pyro-P, Na4P2OT), sodium tripolyphosphate (tripoly-P, Na3P3O10), and sodium hexametaphosphate (meta-P, (NaPO3)6) were selected as the model compounds of condensed phosphate to investigate the adsorption behavior of condensed phosphate on aluminum hydroxide. The adsorption was found to be endothermic and divisible into two stages: (1) fast adsorption within 1 h; and (2) slow adsorption between 1 and 24 h. The modified Freundlich model simulated the fast adsorption stage well; the slow adsorption stage was described well by the first-order kinetics. The activation energies of pyro-P, tripoly-P, and meta-P adsorption on aluminum hydroxide were determined to be 20.2, 22.8 and 10.9 kJ/mol P adsorbed, respectively, in the fast adsorption stage and to be 66.3, 53.5 and 72.5 kJ/mol P adsorbed, respectively, in the slow adsorption stage. The adsorption increased the negative charge of the aluminum hydroxide surface. Transmission electron microscopy and energy dispersive X-ray analysis analyses provided evidence that the adsorption was not uniform on the surface and that the small crystals contributed more to the fast adsorption than the normal sites did. The results from X-ray fluorescence spectrometry and X-ray photoelectron spectroscopy tests also revealed the uneven adsorption of condensed phosphate as a function of the penetration depth. More condensed phosphates were adsorbed on the outer surface of aluminum hydroxide than in its inner parts.
基金This study was supported by the Natural Science Foundation of China (grant No. 40273034)the Science Foundation of Hongzhou Danzi University.
文摘The static flux chamber method was applied to study natural emissions of methane to the atmosphere in the Luntai fault region of Yakela Condensed Oil/Gas Field in the Tarim Basin, Xinjiang Municipality, northwestern China. Using an online method, which couples together a gas chromatography/high-temperature conversion/isotope ratio mass spectrometry (GC/C/MS), 13^C/12^C ratios of methane in flux chambers were measured and showed that methane gases are liable to migrate from deep oil/gas reservoirs to the surface through fault regions and that a part of the migrated methane, which remains unoxidized can be emitted into the atmosphere. Methane emission rates were found to be highest in the mornings, lowest in the afternoons and then increase gradually in the evenings. Methane emission rates varied dramatically in different locations in the fault region. The highest methane emission rate was 10.96 mg/m^2·d, the lowest 4.38 mg/m^2, and the average 7.55 mg/ m^2·d. The 13^C/12^C ratios of the methane in the flux chambers became heavier as the enclosed methane concentrations increased gradually, which reveals that methane released from the fault region might come from thermogenic methane of the deep condensed oil/gas reservoir.
基金the National Natural Sci-ence Foundation of China (No. 40273034)the Science Foundation of Hangzhou Dianzi University
文摘A static flux chamber method was applied to study natural emissions of methane into the atmosphere in the Yakela condensed oil/gas field in Talimu Basin, Xinjiang, China. Using an online method, which couples a gas chromatography/high-temperature conversion/isotope ratio mass spectrometry (GC/C/MS) together, the 13C/12C ratios of methane in the flux chambers were measured. The results demonstrated that methane gases were liable to migrate from deep oil/gas reservoir to the surface through microseepage and p...
基金supported by the Program for New Century Excellent Talents in University, China Ministry of Education, 2009 (No. NCET-10-0768)the National Natural Science Foundation of China (Nos. 20876176 and 51172285)the Natural Science Foundation of Shandong Province (ZR2011EL031, ZR2011EL030)
文摘As a kind of low-cost and readily available industrial byproduct, ethylene tar (ET) was for the first time utilized for the preparation of heat-resistant condensed polynuclear aromatic resin (COPNAR). The basic properties of ET and the resulted COPNAR were characterized by FT-IR, IH-NMR, TGA and elemental analysis. The test results showed that ET with high aromatic content (〉50%) was suitable for the synthesis of COPNAR with superior heat resistance. The average molecular structure of ET was obtained by means of the improved Brown-Ladner method, and the reaction mechanism was considered as an acid-catalyzed positive ion-typed polymerization. Our findings have provided a new route to develop ET into technology-added heat-resistant resins.
基金Project supported by the National Natural Science Foundation of China(Nos.51878383 and51378293)。
文摘A new type of Galerkin finite element for first-order initial-value problems(IVPs)is proposed.Both the trial and test functions employ the same m-degreed polynomials.The adjoint equation is used to eliminate one degree of freedom(DOF)from the test function,and then the so-called condensed test function and its consequent condensed Galerkin element are constructed.It is mathematically proved and numerically verified that the condensed element produces the super-convergent nodal solutions of O(h^(2m+2)),which is equivalent to the order of accuracy by the conventional element of degree m+1.Some related properties are addressed,and typical numerical examples of both linear and nonlinear IVPs of both a single equation and a system of equations are presented to show the validity and effectiveness of the proposed element.
基金supported by the National Natural Science Foundation of China (Grant No.52006099)the Fundamental Research Funds of the Central Universities (Grant No.30920021102,No.309181B8812)the Six Talent Peaks Project of Jiangsu Province of China (Grant No.2016-HKHT-017)。
文摘Aluminum(Al) particles are commonly added to energetic materials including propellants,explosives and pyrotechnics to increase the overall energy density of the composite,but aluminum agglomeration on the combustion surface may lower the combustion efficiency of propellants,resulting in a loss in twophase flow.Therefore,it is necessary to understand the agglomeration mechanism of aluminum particles on the combustion surface.In this paper,a high-pressure sealed combustion chamber is constructed,and high-speed camera is used to capture the whole process of aluminum accumulation,aggregation and agglomeration on the combustion surface,and the secondary agglomeration process near the combustion surface.The microscopic morphology and chemical composition of the condensed combustion products(CCPs) are then studied by using scanning electron microscopy coupled with energy dispersive(SEM-EDS) method.Results show that there are three main types of condensed combustion products:small smoke oxide particles oxidized by aluminum vapor,usually less than 1 μm;typical agglomerates formed by the combustion of aluminum agglomerates;carbonized agglomerates that are widely distributed,usually formed by irregular movements of aluminum agglomerates.The particle size of condensed combustion products is measured by laser particle size meter.As the pressure increases from 0.5 MPa to 1.0 MPa in nitrogen,the mass average particle size of aluminum agglomerates decreases by 49.7%.As the ambient gas is changed from 0.5 MPa nitrogen to 0.5 MPa air,the mass average particle size of aluminum agglomerates decreases by 67.3%.Results show that as the ambient pressure increases,the higher oxygen content can improve combustion efficiency and reduce the average agglomeration size of aluminum particles.
文摘Lead has caused serious environmental pollution due to its toxicity, accumulation in food chains and persistence in nature. In this paper, removal of lead from aqueous solutions is investigated using a novel gel adsorbent synthesized from natural condensed tannin. The novel adsorbent performs in aqueous solutions as a weak base with valid basic groups of 1.2mmol·g-1 tannin gel particles and therefore results in the elevation of pH value of aqueous solutions. Even when initial pH is 3.6, final pH at equilibrium can climb up to 6.5 that is above the pH value for Pb(OH)2 precipitation formation and then lead can be removed from wastewater by this so-called surface precipitation. The adsorption isotherm can be expressed by the Langmuir equation and the maximum capacity for adsorption of Pb is up to 92 mg·g-1 (based on dry adsorbent) when initial pH value is 3.6. Hence, the adsorbent does offer favorable properties in lead removal with respect to its high adsorption capacity at low initial pH value, which is advantageous to lead removal from acidic wastewater. A model is put forward to describe the individual adsorption phenomenon of the tannin gel adsorbent.
基金the Key Research Foundation of the Education Bureau of Hunan Province of China under Grant No.08A015the Natural Science Foundation of Hunan Province of China under Grant No.06JJ2014 and 04JJ40006the National Natural Science Foundation of China under Grant No.10575034
文摘The chaotic ratchet effect for Bos-Einstein condensed atoms in an optical lattice is investigated. By using the direct perturbation method we obtain the chaotic solution of the condensed system. Theoretical analysis reveals that the transport of the condensed atoms in the ratchet potential is a chaotic one, and corresponding numerical results agree well with the theoretical results.
文摘According to the definitions of molecular connectivity and hyper-Wiener index, a novel set of hyper-Wiener indexes (Dn, ^mDn) were defined and named as condensed extended hyper-Wiener index, the potential usefulness of which in QSAR/QSPR is evaluated by its correlation with a number of C3-C8 alkanes as well as by a favorable comparison with models based on molecular connectivity index and overall Wiener index.
文摘In this paper n-hexane is chosen as typical volatile in condensed mode polymerization process, and the adsorption equilibrium of volatile in polyethylene particles is studied through experiments at different temperatures, pressures and particle diameters. It is found that more adsorbed quantity of volatile at equilibrium can be obtained with lower temperature, higher pressure and smaller particle diameter. Under polymerization conditions, the adsorbed quantity at equilibrium is more strongly affected by temperature than by pressure, and if the diameter distribution of particles is very wide the effect of diameter on the adsorbed quantity must be taken into consideration. With theoretical analyses a model is proposed for calculating the adsorbed quantity of volatile at equilibrium.
文摘The study of wave propagation in finite/infinite media has many applications in geotechnical and structural earthquake engineering and has been a focus of research for the past few decades. This paper presents an analysis of 2D anti- plane problems (Love waves) and 2D in-plane problems (Rayleigh waves) in the frequency domain in media consisting of a near-field irregular and a far-field regular part. The near field part may contain structures and its boundaries with the far-field can be of any shape. In this study, the irregular boundaries of the near-field are treated as consistent boundaries, extending the concept of Lysmer's vertical consistent boundaries. The presented technique is called the Condensed Hyperelements Method (CHM). In this method, the irregular boundary is limited to a vertical boundary at each end that is a consistent boundary at the far-field side. Between the two ends, the medium is discretized with hyperelements. Using static condensation, the stiffness matrix of the far-field is derived for the nodes on the irregular boundary. Examples of the application of the CHM illustrate its excellent accuracy and efficiency.
基金supported by the National Key Research and Development Program of China(Grant No.2021YFA1400200)the National Natural Science Foundation of China(Grant Nos.12025407,92250303,and 11934003)+3 种基金Chinese Academy of Sciences(Grant Nos.YSBR047 and XDB330301)financial support from the National Science Fund for Distinguished Young Scholars(Grant No.12304096)China Postdoctoral Science Foundation(Grant No.2022TQ0362)Special Research Assistant of Chinese Academy of Sciences Foundation。
文摘Our understanding of how photons couple to different degrees of freedom in solids forms the bedrock of ultrafast physics and materials sciences.In this review,the emergent ultrafast dynamics in condensed matter at the attosecond timescale have been intensively discussed.In particular,the focus is put on recent developments of attosecond dynamics of charge,exciton,and magnetism.New concepts and indispensable role of interactions among multiple degrees of freedom in solids are highlighted.Applications of attosecond electronic metrology and future prospects toward attosecond dynamics in condensed matter are further discussed.These pioneering studies promise future development of advanced attosecond science and technology such as attosecond lasers,laser medical engineering,and ultrafast electronic devices.
文摘GCP and APP were used as flame retardants for poplar wood and larch wood,and their flame retardancy(OI), permeability (Surface electron spectroscopy), water-re pellency and corrosion toward nail evaluated. The results showed that GCP is in advance of APP. From the thermal analysis and char composition analysis, it is concluded that GCP mainly functions in condensed phase.