The effect of lignin structural units on enzymatic hydrolysis of lignocellulosic biomass was investigated,especially the inhibitory role of lignin in non-productive adsorption with enzymes.Milled wood lignin(MWL)was i...The effect of lignin structural units on enzymatic hydrolysis of lignocellulosic biomass was investigated,especially the inhibitory role of lignin in non-productive adsorption with enzymes.Milled wood lignin(MWL)was isolated from different hardwoods of poplar,eucalyptus and acacia.The isolated lignin samples were characterized by elemental analysis,gel permeation chromatography,nitrobenzene oxidation and fourier infrared spectroscopy.The mechanism of lignin structural units on enzymatic hydrolysis of cellulose was studied by quartz crystal microbalance(QCM).The results showed that different structural units of lignin had different adsorption capacity for enzymes.The results of nitrobenzene oxidation indicated that the S/G ratio(S:syringyl-like lignin structures;G:guaiacyl-like lignin structures)of lignin of poplar was 0.99,that of eucalyptus was 1.92 and that of acacia was 1.34.According to the results of QCM,the adsorption capacity of the three lignin films was as follows:Poplar MWL(S/G ratio 0.99)<Acacia MWL(S/G ratio 1.34)<Eucalyptus MWL(S/G ratio 1.92).Eucalyptus MWL with higher degree of condensation and S/G ratio showed stronger affinity to enzymes and more non-productive adsorption with enzymes,resulting in less adsorption between enzymes and cellulose,and lower enzymatic hydrolysis efficiency.展开更多
Mesoporous aluminosilicate with cubic ordered structure was synthesized by two-step crystallization, which showed stronger acid sites and more effective activity for catalytic alkylation of 2, 4-ditert-butylphenol wit...Mesoporous aluminosilicate with cubic ordered structure was synthesized by two-step crystallization, which showed stronger acid sites and more effective activity for catalytic alkylation of 2, 4-ditert-butylphenol with tert-butanol than conventional H-AlMCM-48 materials.展开更多
Because of the low price and abundant reserves of sodium compared with lithium,the research of sodium-ion batteries(SIBs)in the field of large-scale energy storage has returned to the research spotlight.Layered oxides...Because of the low price and abundant reserves of sodium compared with lithium,the research of sodium-ion batteries(SIBs)in the field of large-scale energy storage has returned to the research spotlight.Layered oxides distinguish themselves from the mains cathode materials of SIBs owing to their advantages such as high specific capacity,simple synthesis route,and environmental benignity.However,the commercial development of the layered oxides is limited by sluggish kinetics,complex phase transition and poor air stability.Based on the research ideas from macro-to micro-scale,this review systematically summarizes the current optimization strategies of sodium-ion layered oxide cathodes(SLOC)from different dimensions:microstructure design,local chemistry regulation and structural unit construction.In the dimension of microstructure design,the various structures such as the microspheres,nanoplates,nanowires and exposed active facets are prepared to improve the slow kinetics and electrochemical performance.Besides,from the view of local chemistry regulation by chemical element substitution,the intrinsic electron/ion properties of SLOC have been enhanced to strengthen the structural stability.Furthermore,the optimization idea of endeavors to regulate the physical and chemical properties of cathode materials essentially is put forward from the dimension of structural unit construction.The opinions and strategies proposed in this review will provide some inspirations for the design of new SLOC in the future.展开更多
The occurrence of coal-bearing strata in a variety of coal-bearing basins of China is characterized by late tectonic deformation and remarkable spatial and geochronologic differences.The main controlling factors,which...The occurrence of coal-bearing strata in a variety of coal-bearing basins of China is characterized by late tectonic deformation and remarkable spatial and geochronologic differences.The main controlling factors,which determine the tectonic framework of coalfields,include the geodynamic environment,tectonic evolution,deep structures,tectonic stress,and lithologic combination of the coal measures.The Chinese continent has experienced multi-stage tectonic movements since the Late Paleozoic.The spatial and temporal heterogeneity of its continental tectonic evolution,the complexity of its basement properties,and its stratigraphic configurations control the tectonic framework of its coalfields’present complex and orderly patterns.The concept of coal occurrence structural units is proposed in this paper and is defined as the structural zoning of coal occurrence.China’s coalfields are divided into five coal occurrence structural areas,and the structural characteristics of the coalfields in five main coal occurrence areas throughout the country are summarized.Based on the analysis of the relationship between the structure characteristics and occurrence of coal in these coalfields,the coal-controlling structures are divided into six groups:extensional structural styles,compressional structural styles,shearing and rotational structural styles,inverted structural styles,sliding structural styles,and syn-depositional structural styles.In addition,the distribution of coal-controlling structural styles is briefly summarized in this paper.展开更多
A thermodynamic model of calculating mass action concentrations for structural units or ion couples in NaClO4-H2O and NaF-H2O binary solutions and NaClO4-NaF-H2O ternary strong electrolyte aqueous solutions was develo...A thermodynamic model of calculating mass action concentrations for structural units or ion couples in NaClO4-H2O and NaF-H2O binary solutions and NaClO4-NaF-H2O ternary strong electrolyte aqueous solutions was developed based on the ion and molecule coexistence theory (IMCT). A transformation coefficient was needed to compare the calculated mass action concentration and the reported activity, because they were usually obtained at different standard states and concentration units. The results show that transformation coefficients between the calculated mass action concentrations and the reported activities of the same components change in a very narrow range. The transformed mass action concentrations of structural units or ion couples in NaClO4-H2O and NaF-H2O binary solutions agree well with the reported activities. The transformed mass action concentrations of structural units or ion couples in NaClO4-NaF-H2O ternary solution are also in good agreement with the reported activities in a total ionic strength range from 0.1 to 0.9 mol/kg H2O by the 0.1 mol/kg step with different ionic strength fractions of 0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1, respectively. The results indicate that the developed thermodynamic model can reveal the structural characteristics of binary and ternary strong electrolyte aqueous solutions, and the calculated mass action concentrations of structural units or ion couples also strictly follow the mass action law.展开更多
Compound [Cd_(1.5)(ppt)Br_2(H_2O)]_(2n)(1),where Hppt = 3-(pyridin-4-yl)-5-(pyrazin-2-yl)-1H-1,2,4-triazole,has been synthesized under hydrothermal conditions and characterized by elemental analysis,IR s...Compound [Cd_(1.5)(ppt)Br_2(H_2O)]_(2n)(1),where Hppt = 3-(pyridin-4-yl)-5-(pyrazin-2-yl)-1H-1,2,4-triazole,has been synthesized under hydrothermal conditions and characterized by elemental analysis,IR spectra,powder XRD,and X-ray diffraction.Compound 1 crystallizes in the triclinic system,space group P1 with a = 7.4402(6),b = 8.0570(7),c = 12.8674(11) A,α = 89.7300(10),β = 89.8570(10),γ = 68.3910(10)°,V = 717.13(10) A^3,Z = 1,Dc = 2.638 g/cm^3,μ = 7.824 mm^-1,F(000) = 534,the final R = 0.0324 and w R = 0.1084 for 2324 observed reflections with I 〉 2σ(I).X-ray diffraction analyses revealed that complex 1 is a 2D layered coordination polymer constructed from the linkage of [Cd_3(μ-Br)_4] trinuclear units with ppt-spacers,and a 3D supramolecular architecture is further assembled in 1 via hydrogen-bonding contacts.Fluorescence measurements show that 1 has medium fluorescent emission at 450 nm.展开更多
Radical copolymerization of acrylic acid(AA)with acrylamide(AM)or acrylamide/acrylonitrile(AM/AN)was initiated with ammonium persulfate as initiator to produce acrylic copolymers such as bicopolymer poly(AM-co-AA)and ...Radical copolymerization of acrylic acid(AA)with acrylamide(AM)or acrylamide/acrylonitrile(AM/AN)was initiated with ammonium persulfate as initiator to produce acrylic copolymers such as bicopolymer poly(AM-co-AA)and tercopolymer poly(AM-co-AN-co-AA)for revealing the effects of the structural units of the copolymers on the adhesion of the copolymers to polyester or cotton fibers for warp sizing.The adhesion was evaluated in terms of tensile strength and work-to-break of a roving impregnated with the copolymer solution.It was found that the adhesion strongly depended on type and amount of the units incorporated into the copolymeric chains.Whether the fiber is cotton or polyester,the adhesion of the bicopolymer poly(AM-co-AA)is greater than that of polyacrylic acid or polyacyamide.Excessively increasing the amount of AM or AA unit in poly(AM-co-AA)lowers the adhesion.To enhance the adhesion of the bicopolymer,a favorable mole ratio of AM to AA is 70/30.Based on this mole ratio,incorporation of acrylonitrile units into poly(AM-co-AA)to form tercopolymer enhances the adhesion.展开更多
Several novel aromatic liquid crystalline copolyesters with regular sequence structure were prepared by melt Sehotten-Baumann polycondensation via complex monomer. Polarizing microscope with hot stage, thermal analysi...Several novel aromatic liquid crystalline copolyesters with regular sequence structure were prepared by melt Sehotten-Baumann polycondensation via complex monomer. Polarizing microscope with hot stage, thermal analysis and X-ray diffraction were used to investigate the structure and properties of the copolyesters. The effects of structural units, such as flexible spacer, noncolinear meta-linked phenylene unit, crankshaft unit, kink with flexible bridging unit and various substituted benzene rings on melting temperature of aromatic copolyesters were studied and discussed on the basis of crystalline structure of the polymers.展开更多
To design the amorphous hydrogen storage alloy efficiently, the maximum hydrogen capacities for Zr - Ni amorphous alloy were calculated. Based on the Rhomb Unit Structure Model(RUSM) for amorphous alloy and the experi...To design the amorphous hydrogen storage alloy efficiently, the maximum hydrogen capacities for Zr - Ni amorphous alloy were calculated. Based on the Rhomb Unit Structure Model(RUSM) for amorphous alloy and the experimental result that hydrogen atoms exist in 3Zr1Ni and 4Zr tetrahedron interstices in Zr-Ni amolphous alloy, the numbers of 3Zr-1Ni and 4Zr tetrahedron interstices in a RUSM were calculated which correspond to the hydrogen capacity. The two extremum Zr distribution states were calculated, such as highly heterogeneous Zr distribution and homogeneous Zr distribution. The calculated curves of hydrogen capacity with different Zr contents at two states indicate that the hydrogen capacity increases with increasing Zr content and reaches its maximum when Zr is 75%. The theoretical maximum hydrogen capacity for Zr - Ni amorphous alloy is 2.0 (H/M). Meanwhile, the hydrogen capacity of heterogenous Zr distribution alloy is higher than that of homogenous one at the same Zr content. The experimental results prove the calculated results reasonable, and accordingly, the experimental results that the distribution of Zr atom in amorphous alloy occur heterogeneous after a few hydrogen absorption desorption cycles can be explained.展开更多
A model Cu-AlN composite has been prepared by ion implantation technique and annealing. The atomic configuration and lattice relationship of a low-energy inherent interface(11)Cn//(0001)AlN were studied by using trans...A model Cu-AlN composite has been prepared by ion implantation technique and annealing. The atomic configuration and lattice relationship of a low-energy inherent interface(11)Cn//(0001)AlN were studied by using transmission electron microscopy and geometrical modelling. By analysing the dichromatic pattern of the composite,a primary structural unit of the interface atomic configuration was determined for purpose of HREM image simulations and of studying the structurul relaxation state in the near-interface region.展开更多
In the global competition for talents,the massive inflow of Chinese students into the UK has drawn great attention.However,only a few studies examine students’interactions with socioeconomic structures in their study...In the global competition for talents,the massive inflow of Chinese students into the UK has drawn great attention.However,only a few studies examine students’interactions with socioeconomic structures in their study-to-work transition.This study used Higher Education Statistics AgencyHESA,22data and interview data collected from Chinese postgraduate students,and it aims to:investigate structural factors that influence post-study migration patterns of Chinese students;and explore how Chinese students interact with wider social structures.This study found that different configurations between students"goals,""actions,"and"reflexivity"would lead to different employment outcomes.Three different study-to-work transition strategies were identified:"proceeding without a fixed plan";"reaching a compromise";and"knowing goals and approaching goals".Findings suggest that the transition between study and work is more complex than what is described in human capital and push-pull approaches.A better understanding of students’decision-making processes would help higher education institutions in preparing graduates for careers in the global labour market.展开更多
Coal-fired power is the main power source and the biggest contributor to energy conservation in the past several decades in China.It is generally believed that advanced technology should be counted on for energy conse...Coal-fired power is the main power source and the biggest contributor to energy conservation in the past several decades in China.It is generally believed that advanced technology should be counted on for energy conservation.However,a review of the decline in the national average net coal consumption rate(NCCR)of China's coal-fired power industry along with its development over the past few decades indicates that the upgradation of the national unit capacity structure(including installing advanced production and phasing out backward production)plays a more important role.A quantitative study on the effect of the unit capacity structure upgradation on the decline in the national average NCCR suggests that phasing out backward production is the leading factor for the decline in the NCCR in the past decade,followed by the new installation,whose sum contributes to approximately 80%of the decline in the national average NCCR.The new installation has an effective affecting period of about 8 years,during which it would gradually decline from a relatively high value.Since the effect of phasing out backward production may remain at a certain degree given a continual action of phasing out backward capacity,it is suggested that the organized action of phasing out backward production should be insisted on.展开更多
The Chinese civilization is a highly developed,long-standing and comprehensive entity,materially,spiritually and institutionally created by the Chinese nation.Around 6000 BC,Early China in the cultural sense bears its...The Chinese civilization is a highly developed,long-standing and comprehensive entity,materially,spiritually and institutionally created by the Chinese nation.Around 6000 BC,Early China in the cultural sense bears its root,marking the first stage of the origin of Chinese civilization.Around 4000 BC,Early China in the cultural sense formally takes shape,marking the second stage of the origin of Chinese civilization.Around 3100 BC,with the emergence of Chinese civilization,the stage of the Archaic State begins.Around 2100 BC,Early China enters the stage of the Dynastic State.Chinese civilization,with its universalistic cosmology and united structure,is of a unique"Tianxia(all under heaven)civilization"pattern.The"Tianxia civilization"patern,together with other cultural genes such as ritualism,ancestral worship,sincerity,benevolence,and coexistence of all in harmony,is the root cause for the continuous development of Chinese civilization to date.展开更多
Raoultian activity coefficients γ0c of C in infinitely dilute Fe-C binary melts at temperatures of 1833, 1873, 1923, and 1973 K have been determined from the converted mass action concentrations Nc of C in Fe-C binar...Raoultian activity coefficients γ0c of C in infinitely dilute Fe-C binary melts at temperatures of 1833, 1873, 1923, and 1973 K have been determined from the converted mass action concentrations Nc of C in Fe-C binary melts by the developed AMCT-Ni model based on the atom-molecule coexistence theory (AMCT). The obtained expression of γ0c by the developed AMCT-Ni model has been evaluated to be accurate based on the reported ones from the literature. Meanwhile, three activity coefficients γc,f%,c, andfH,c of C coupled with activity aR,C or a%,c or aH,c have been obtained by the developed AMCT-Ni model and assessed through comparing with the predicted ones by other models from the literature. The first-order activity interaction coefficients ec, ec, and hcc related to γc f%,c, and fH,c are also determined and assessed in comparison with the reported ones from the literature. Furthermore, the integral molar mixing thermodynamic functions such as AmixHm,Fe-C, △mix-Sm,Fe-C, and △mixGm,Fe-C of Fe-C binary melts over a temperature range from 1833 to 1973 K have been determined and evaluated to be valid based on the determined ones from the literature.展开更多
Systems Science principles are the universal fundamental philosophical principles for analyzing, understanding, reforming and perfecting the objective world. This paper presents a Systems-Science-Based Knowledge Model...Systems Science principles are the universal fundamental philosophical principles for analyzing, understanding, reforming and perfecting the objective world. This paper presents a Systems-Science-Based Knowledge Model (SSBKM) to establish a more general knowledge structure model. It can be regarded as a development of frame representation for discovering and constructing slot structures as well as the frame structures. With this model the paper also presents a System-Sciences-Based Object-Oriented Analysis method (SSBOOA), which is a strategy to find and determine object classes and class structures, the relations between object instances of different classes, not to just explain classes. Finally, the paper illustrates knowledge analysis and computerizing (synthesizing) steps in an example of SSBKM of cognitive psychology-based CAI Network for Teaching Middle School Mathematics.展开更多
The Chinese Materials Research Society(C-MRS)Conference(2015)was held in the Guizhou Park Hotel International Conference Center,Guiyang,China,from July 10-14,2015.This conference consists of 30symposia,including 4...The Chinese Materials Research Society(C-MRS)Conference(2015)was held in the Guizhou Park Hotel International Conference Center,Guiyang,China,from July 10-14,2015.This conference consists of 30symposia,including 4international symposia.As one of 4international symposia,"Serration and noise behavior in advanced materials"展开更多
Blended-Wing-Body(BWB)aircraft is promoted as one of the most possible layouts to achieve more sustainable civil aviation.Due to the non-circular cross-section of the center-body,a bulge deformation forms over the upp...Blended-Wing-Body(BWB)aircraft is promoted as one of the most possible layouts to achieve more sustainable civil aviation.Due to the non-circular cross-section of the center-body,a bulge deformation forms over the upper surface of the body under the coupled loads of the internal pressurization of the cabin and the aerodynamic bending moments of the wing,which reduces the lift-to-drag ratio of BWB aircraft.Under a limited deformation,the relationship between the aerodynamic performance and the structural weight needs to be studied.In this work,the effects of stiffness constraints on the center-body deformation,structural weight of the airframe and aerodynamic performance were investigated by using an analytical model of the Pultruded Rod Stitched Efficient Unitized Structure(PRSEUS)for the airframe and the computational fluid dynamics method,respectively.The results show that as the stiffness constraint increases,the spacings between the rod stringers and the frame stiffeners decrease,and the structural weight increases inversely.A 5.2% reduction of the lift-to-drag ratio is encountered at cruise for a medium deformation design of 42.8 mm/m.A higher aerodynamic penalty is suffered when the stiffness constraint is further released.The final deformation criterion is different when the weight vector of the aerodynamic performance and structural weight is different.展开更多
基金National Natural Science Foundation of China(31730106,21704045).
文摘The effect of lignin structural units on enzymatic hydrolysis of lignocellulosic biomass was investigated,especially the inhibitory role of lignin in non-productive adsorption with enzymes.Milled wood lignin(MWL)was isolated from different hardwoods of poplar,eucalyptus and acacia.The isolated lignin samples were characterized by elemental analysis,gel permeation chromatography,nitrobenzene oxidation and fourier infrared spectroscopy.The mechanism of lignin structural units on enzymatic hydrolysis of cellulose was studied by quartz crystal microbalance(QCM).The results showed that different structural units of lignin had different adsorption capacity for enzymes.The results of nitrobenzene oxidation indicated that the S/G ratio(S:syringyl-like lignin structures;G:guaiacyl-like lignin structures)of lignin of poplar was 0.99,that of eucalyptus was 1.92 and that of acacia was 1.34.According to the results of QCM,the adsorption capacity of the three lignin films was as follows:Poplar MWL(S/G ratio 0.99)<Acacia MWL(S/G ratio 1.34)<Eucalyptus MWL(S/G ratio 1.92).Eucalyptus MWL with higher degree of condensation and S/G ratio showed stronger affinity to enzymes and more non-productive adsorption with enzymes,resulting in less adsorption between enzymes and cellulose,and lower enzymatic hydrolysis efficiency.
基金We thank financial support by the National Natural Science Foundation of China(grant 29973001).
文摘Mesoporous aluminosilicate with cubic ordered structure was synthesized by two-step crystallization, which showed stronger acid sites and more effective activity for catalytic alkylation of 2, 4-ditert-butylphenol with tert-butanol than conventional H-AlMCM-48 materials.
基金supported by the National Natural Science Foundation of China(51971124,52171217)the State Key Laboratory of Electrical Insulation and Power Equipment,Xi’an Jiaotong University(EIPE22208)+5 种基金the National Postdoctoral Program for Innovative Talents(BX20200222)the China Postdoctoral Science Foundation(2020M682878)Zhejiang Natural Science Foundation(LQ23E020002)Wenzhou Natural Science Foundation(G20220019)Cooperation between industry and education project of Ministry of Education(220601318235513)National Natural Science Foundation of China(52202284)。
文摘Because of the low price and abundant reserves of sodium compared with lithium,the research of sodium-ion batteries(SIBs)in the field of large-scale energy storage has returned to the research spotlight.Layered oxides distinguish themselves from the mains cathode materials of SIBs owing to their advantages such as high specific capacity,simple synthesis route,and environmental benignity.However,the commercial development of the layered oxides is limited by sluggish kinetics,complex phase transition and poor air stability.Based on the research ideas from macro-to micro-scale,this review systematically summarizes the current optimization strategies of sodium-ion layered oxide cathodes(SLOC)from different dimensions:microstructure design,local chemistry regulation and structural unit construction.In the dimension of microstructure design,the various structures such as the microspheres,nanoplates,nanowires and exposed active facets are prepared to improve the slow kinetics and electrochemical performance.Besides,from the view of local chemistry regulation by chemical element substitution,the intrinsic electron/ion properties of SLOC have been enhanced to strengthen the structural stability.Furthermore,the optimization idea of endeavors to regulate the physical and chemical properties of cathode materials essentially is put forward from the dimension of structural unit construction.The opinions and strategies proposed in this review will provide some inspirations for the design of new SLOC in the future.
基金This study was financially supported by the Geological Survey Project of China Geological Survey National Potential Evaluation of Coal Resources project(121211121043)the National Natural Science Foundation of China(41572141,41772156).
文摘The occurrence of coal-bearing strata in a variety of coal-bearing basins of China is characterized by late tectonic deformation and remarkable spatial and geochronologic differences.The main controlling factors,which determine the tectonic framework of coalfields,include the geodynamic environment,tectonic evolution,deep structures,tectonic stress,and lithologic combination of the coal measures.The Chinese continent has experienced multi-stage tectonic movements since the Late Paleozoic.The spatial and temporal heterogeneity of its continental tectonic evolution,the complexity of its basement properties,and its stratigraphic configurations control the tectonic framework of its coalfields’present complex and orderly patterns.The concept of coal occurrence structural units is proposed in this paper and is defined as the structural zoning of coal occurrence.China’s coalfields are divided into five coal occurrence structural areas,and the structural characteristics of the coalfields in five main coal occurrence areas throughout the country are summarized.Based on the analysis of the relationship between the structure characteristics and occurrence of coal in these coalfields,the coal-controlling structures are divided into six groups:extensional structural styles,compressional structural styles,shearing and rotational structural styles,inverted structural styles,sliding structural styles,and syn-depositional structural styles.In addition,the distribution of coal-controlling structural styles is briefly summarized in this paper.
基金supported by the Publication Foundation of China National Science and Technology Academic Books
文摘A thermodynamic model of calculating mass action concentrations for structural units or ion couples in NaClO4-H2O and NaF-H2O binary solutions and NaClO4-NaF-H2O ternary strong electrolyte aqueous solutions was developed based on the ion and molecule coexistence theory (IMCT). A transformation coefficient was needed to compare the calculated mass action concentration and the reported activity, because they were usually obtained at different standard states and concentration units. The results show that transformation coefficients between the calculated mass action concentrations and the reported activities of the same components change in a very narrow range. The transformed mass action concentrations of structural units or ion couples in NaClO4-H2O and NaF-H2O binary solutions agree well with the reported activities. The transformed mass action concentrations of structural units or ion couples in NaClO4-NaF-H2O ternary solution are also in good agreement with the reported activities in a total ionic strength range from 0.1 to 0.9 mol/kg H2O by the 0.1 mol/kg step with different ionic strength fractions of 0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1, respectively. The results indicate that the developed thermodynamic model can reveal the structural characteristics of binary and ternary strong electrolyte aqueous solutions, and the calculated mass action concentrations of structural units or ion couples also strictly follow the mass action law.
基金supported by the National Natural Science Foundation of China(No.21271098)Science and Technology Research Key Project of the Education Department of Henan Province(No.14B150034)
文摘Compound [Cd_(1.5)(ppt)Br_2(H_2O)]_(2n)(1),where Hppt = 3-(pyridin-4-yl)-5-(pyrazin-2-yl)-1H-1,2,4-triazole,has been synthesized under hydrothermal conditions and characterized by elemental analysis,IR spectra,powder XRD,and X-ray diffraction.Compound 1 crystallizes in the triclinic system,space group P1 with a = 7.4402(6),b = 8.0570(7),c = 12.8674(11) A,α = 89.7300(10),β = 89.8570(10),γ = 68.3910(10)°,V = 717.13(10) A^3,Z = 1,Dc = 2.638 g/cm^3,μ = 7.824 mm^-1,F(000) = 534,the final R = 0.0324 and w R = 0.1084 for 2324 observed reflections with I 〉 2σ(I).X-ray diffraction analyses revealed that complex 1 is a 2D layered coordination polymer constructed from the linkage of [Cd_3(μ-Br)_4] trinuclear units with ppt-spacers,and a 3D supramolecular architecture is further assembled in 1 via hydrogen-bonding contacts.Fluorescence measurements show that 1 has medium fluorescent emission at 450 nm.
基金Open Research Foundation of "Anhui Key Laboratory of Textile Materials",China(No.2006F2003)
文摘Radical copolymerization of acrylic acid(AA)with acrylamide(AM)or acrylamide/acrylonitrile(AM/AN)was initiated with ammonium persulfate as initiator to produce acrylic copolymers such as bicopolymer poly(AM-co-AA)and tercopolymer poly(AM-co-AN-co-AA)for revealing the effects of the structural units of the copolymers on the adhesion of the copolymers to polyester or cotton fibers for warp sizing.The adhesion was evaluated in terms of tensile strength and work-to-break of a roving impregnated with the copolymer solution.It was found that the adhesion strongly depended on type and amount of the units incorporated into the copolymeric chains.Whether the fiber is cotton or polyester,the adhesion of the bicopolymer poly(AM-co-AA)is greater than that of polyacrylic acid or polyacyamide.Excessively increasing the amount of AM or AA unit in poly(AM-co-AA)lowers the adhesion.To enhance the adhesion of the bicopolymer,a favorable mole ratio of AM to AA is 70/30.Based on this mole ratio,incorporation of acrylonitrile units into poly(AM-co-AA)to form tercopolymer enhances the adhesion.
文摘Several novel aromatic liquid crystalline copolyesters with regular sequence structure were prepared by melt Sehotten-Baumann polycondensation via complex monomer. Polarizing microscope with hot stage, thermal analysis and X-ray diffraction were used to investigate the structure and properties of the copolyesters. The effects of structural units, such as flexible spacer, noncolinear meta-linked phenylene unit, crankshaft unit, kink with flexible bridging unit and various substituted benzene rings on melting temperature of aromatic copolyesters were studied and discussed on the basis of crystalline structure of the polymers.
基金Supported by Foundation of National Nature Science(59872024)
文摘To design the amorphous hydrogen storage alloy efficiently, the maximum hydrogen capacities for Zr - Ni amorphous alloy were calculated. Based on the Rhomb Unit Structure Model(RUSM) for amorphous alloy and the experimental result that hydrogen atoms exist in 3Zr1Ni and 4Zr tetrahedron interstices in Zr-Ni amolphous alloy, the numbers of 3Zr-1Ni and 4Zr tetrahedron interstices in a RUSM were calculated which correspond to the hydrogen capacity. The two extremum Zr distribution states were calculated, such as highly heterogeneous Zr distribution and homogeneous Zr distribution. The calculated curves of hydrogen capacity with different Zr contents at two states indicate that the hydrogen capacity increases with increasing Zr content and reaches its maximum when Zr is 75%. The theoretical maximum hydrogen capacity for Zr - Ni amorphous alloy is 2.0 (H/M). Meanwhile, the hydrogen capacity of heterogenous Zr distribution alloy is higher than that of homogenous one at the same Zr content. The experimental results prove the calculated results reasonable, and accordingly, the experimental results that the distribution of Zr atom in amorphous alloy occur heterogeneous after a few hydrogen absorption desorption cycles can be explained.
文摘A model Cu-AlN composite has been prepared by ion implantation technique and annealing. The atomic configuration and lattice relationship of a low-energy inherent interface(11)Cn//(0001)AlN were studied by using transmission electron microscopy and geometrical modelling. By analysing the dichromatic pattern of the composite,a primary structural unit of the interface atomic configuration was determined for purpose of HREM image simulations and of studying the structurul relaxation state in the near-interface region.
基金This research is supported by the Wenzhou Social Science Fund(Grant No.21JD10).
文摘In the global competition for talents,the massive inflow of Chinese students into the UK has drawn great attention.However,only a few studies examine students’interactions with socioeconomic structures in their study-to-work transition.This study used Higher Education Statistics AgencyHESA,22data and interview data collected from Chinese postgraduate students,and it aims to:investigate structural factors that influence post-study migration patterns of Chinese students;and explore how Chinese students interact with wider social structures.This study found that different configurations between students"goals,""actions,"and"reflexivity"would lead to different employment outcomes.Three different study-to-work transition strategies were identified:"proceeding without a fixed plan";"reaching a compromise";and"knowing goals and approaching goals".Findings suggest that the transition between study and work is more complex than what is described in human capital and push-pull approaches.A better understanding of students’decision-making processes would help higher education institutions in preparing graduates for careers in the global labour market.
基金China Postdoctoral Science Foundation (No.2017M620758)Special Funds of the National Natural Science Foundation of China(Grant No.L1522032)the Consulting Project of Chinese Academy of Engineering(No.2015-ZCQ-06).
文摘Coal-fired power is the main power source and the biggest contributor to energy conservation in the past several decades in China.It is generally believed that advanced technology should be counted on for energy conservation.However,a review of the decline in the national average net coal consumption rate(NCCR)of China's coal-fired power industry along with its development over the past few decades indicates that the upgradation of the national unit capacity structure(including installing advanced production and phasing out backward production)plays a more important role.A quantitative study on the effect of the unit capacity structure upgradation on the decline in the national average NCCR suggests that phasing out backward production is the leading factor for the decline in the NCCR in the past decade,followed by the new installation,whose sum contributes to approximately 80%of the decline in the national average NCCR.The new installation has an effective affecting period of about 8 years,during which it would gradually decline from a relatively high value.Since the effect of phasing out backward production may remain at a certain degree given a continual action of phasing out backward capacity,it is suggested that the organized action of phasing out backward production should be insisted on.
基金the key project of the National Social Science Foundation"Study on the Civilization Process of Early China from the Eurasian Perspective"(18ZDA172)the key project of Source of China and Songshan Civilization Research Committee in Zhengzhou"The Regional Pattern Study on the Origination of Early Chinese Civilization".
文摘The Chinese civilization is a highly developed,long-standing and comprehensive entity,materially,spiritually and institutionally created by the Chinese nation.Around 6000 BC,Early China in the cultural sense bears its root,marking the first stage of the origin of Chinese civilization.Around 4000 BC,Early China in the cultural sense formally takes shape,marking the second stage of the origin of Chinese civilization.Around 3100 BC,with the emergence of Chinese civilization,the stage of the Archaic State begins.Around 2100 BC,Early China enters the stage of the Dynastic State.Chinese civilization,with its universalistic cosmology and united structure,is of a unique"Tianxia(all under heaven)civilization"pattern.The"Tianxia civilization"patern,together with other cultural genes such as ritualism,ancestral worship,sincerity,benevolence,and coexistence of all in harmony,is the root cause for the continuous development of Chinese civilization to date.
文摘Raoultian activity coefficients γ0c of C in infinitely dilute Fe-C binary melts at temperatures of 1833, 1873, 1923, and 1973 K have been determined from the converted mass action concentrations Nc of C in Fe-C binary melts by the developed AMCT-Ni model based on the atom-molecule coexistence theory (AMCT). The obtained expression of γ0c by the developed AMCT-Ni model has been evaluated to be accurate based on the reported ones from the literature. Meanwhile, three activity coefficients γc,f%,c, andfH,c of C coupled with activity aR,C or a%,c or aH,c have been obtained by the developed AMCT-Ni model and assessed through comparing with the predicted ones by other models from the literature. The first-order activity interaction coefficients ec, ec, and hcc related to γc f%,c, and fH,c are also determined and assessed in comparison with the reported ones from the literature. Furthermore, the integral molar mixing thermodynamic functions such as AmixHm,Fe-C, △mix-Sm,Fe-C, and △mixGm,Fe-C of Fe-C binary melts over a temperature range from 1833 to 1973 K have been determined and evaluated to be valid based on the determined ones from the literature.
文摘Systems Science principles are the universal fundamental philosophical principles for analyzing, understanding, reforming and perfecting the objective world. This paper presents a Systems-Science-Based Knowledge Model (SSBKM) to establish a more general knowledge structure model. It can be regarded as a development of frame representation for discovering and constructing slot structures as well as the frame structures. With this model the paper also presents a System-Sciences-Based Object-Oriented Analysis method (SSBOOA), which is a strategy to find and determine object classes and class structures, the relations between object instances of different classes, not to just explain classes. Finally, the paper illustrates knowledge analysis and computerizing (synthesizing) steps in an example of SSBKM of cognitive psychology-based CAI Network for Teaching Middle School Mathematics.
文摘The Chinese Materials Research Society(C-MRS)Conference(2015)was held in the Guizhou Park Hotel International Conference Center,Guiyang,China,from July 10-14,2015.This conference consists of 30symposia,including 4international symposia.As one of 4international symposia,"Serration and noise behavior in advanced materials"
基金supported partially by the National Key Laboratory Project,China(No.61422010201).
文摘Blended-Wing-Body(BWB)aircraft is promoted as one of the most possible layouts to achieve more sustainable civil aviation.Due to the non-circular cross-section of the center-body,a bulge deformation forms over the upper surface of the body under the coupled loads of the internal pressurization of the cabin and the aerodynamic bending moments of the wing,which reduces the lift-to-drag ratio of BWB aircraft.Under a limited deformation,the relationship between the aerodynamic performance and the structural weight needs to be studied.In this work,the effects of stiffness constraints on the center-body deformation,structural weight of the airframe and aerodynamic performance were investigated by using an analytical model of the Pultruded Rod Stitched Efficient Unitized Structure(PRSEUS)for the airframe and the computational fluid dynamics method,respectively.The results show that as the stiffness constraint increases,the spacings between the rod stringers and the frame stiffeners decrease,and the structural weight increases inversely.A 5.2% reduction of the lift-to-drag ratio is encountered at cruise for a medium deformation design of 42.8 mm/m.A higher aerodynamic penalty is suffered when the stiffness constraint is further released.The final deformation criterion is different when the weight vector of the aerodynamic performance and structural weight is different.