A novel radiation tolerant SOI isolation structure,consisting of thin SiO2/polysilicon/field SiO2 multilayers,is proposed. A device with this structure does not show obvious changes in subthreshold characteristics and...A novel radiation tolerant SOI isolation structure,consisting of thin SiO2/polysilicon/field SiO2 multilayers,is proposed. A device with this structure does not show obvious changes in subthreshold characteristics and leakage current,indicating a superior radiation tolerance to traditional LOCOS.展开更多
A theoretical model of a friction pendulum system （FPS） is introduced to examine its application for the seismic isolation of spatial lattice shell structures. An equation of motion of the lattice shell with FPS bea...A theoretical model of a friction pendulum system （FPS） is introduced to examine its application for the seismic isolation of spatial lattice shell structures. An equation of motion of the lattice shell with FPS bearings is developed. Then, seismic isolation studies are performed for both double-layer and single-layer lattice shell structures under different seismic input and design parameters of the FPS. The influence of frictional coefficients and radius of the FPS on seismic performance are discussed. Based on the study, some suggestions for seismic isolation design of lattice shells with FPS bearings are given and conclusions are made which could be helpful in the application of FPS.展开更多
Panax notoginseng is a traditional Chinese medicine containing various constituents,including the saponins,polysaccharides,polyacetylenes,amino acids,etc.It has beneficial functions,such as the anti-inflammatory,antit...Panax notoginseng is a traditional Chinese medicine containing various constituents,including the saponins,polysaccharides,polyacetylenes,amino acids,etc.It has beneficial functions,such as the anti-inflammatory,antitumor,hepatoprotective,and anti-aging effects.Among these,P.notoginseng polysaccharides(PNPs)have been exploited because of their extensive pharmacological effects,being ranked as one of the current research hotspots,especially for the functional foods and medical practice.In this review,the literature related to PNPs in the past 20 years was surveyed and analyzed using both the China National Knowledge Infrastructure(CNKI)and Web of Science(WOS)databases.The visualization diagram shows that current studies on PNPs mainly focus on the antioxidant and immunomodulatory activities and structural characterization.In addition,the extraction,separation,purification,chemical analysis,structural characteristics,bioactivities,and applications of PNPs are outlined,in detail,aimed to provide valuable information for the further study,development,and utilization regarding PNPs.展开更多
Finding an optimal isolator arrangement for asymmetric structures using traditional conceptual design methods that can significantly minimize torsional response while ensuring efficient horizontal seismic isolation is...Finding an optimal isolator arrangement for asymmetric structures using traditional conceptual design methods that can significantly minimize torsional response while ensuring efficient horizontal seismic isolation is cumbersome and inefficient.Thus,this work develops a multi-objective optimization method to enhance the torsional resistance of asymmetric base-isolated structures.The primary objective is to simultaneously minimize the interstory rotation of the superstructure,the rotation of the isolation layer,and the interstory displacement of the superstructure without exceeding the isolator displacement limits.A fast non-dominated sorting genetic algorithm(NSGA-Ⅱ)is employed to satisfy this optimization objective.Subsequently,the isolator arrangement,encompassing both positions and categories,is optimized according to this multi-objective optimization method.Additionally,an optimization design platform is developed to streamline the design operation.This platform integrates the input of optimization parameters,the output of optimization results,the finite element analysis,and the multi-objective optimization method proposed herein.Finally,the application of this multi-objective optimization method and its associated platform are demonstrated on two asymmetric base-isolated structures of varying heights and plan configurations.The results indicate that the optimal isolator arrangement derived from the optimization method can further improve the control over the lateral and torsional responses of asymmetric base-isolated structures compared to conventional conceptual design methods.Notably,the interstory rotation of the optimal base-isolated structure is significantly reduced,constituting only approximately 33.7%of that observed in the original base-isolated structure.The proposed platform facilitates the automatic generation of the optimal design scheme for the isolators of asymmetric base-isolated structures,offering valuable insights and guidance for the burgeoning field of intelligent civil engineering design.展开更多
Semi-active dampers are used in base-isolation to reduce the seismic response of civil engineering structures. In the present study, a new semi-active damping system using variable amplification will be investigated f...Semi-active dampers are used in base-isolation to reduce the seismic response of civil engineering structures. In the present study, a new semi-active damping system using variable amplification will be investigated for adaptive baseisolation. It uses a novel variable amplification device （VAD） connected in series with a passive damper. The VAD is capable of producing multiple amplification factors, each corresponding to a different amplification state. Forces from the damper are amplified to the structure according to the current amplification state, which is selected via a semi-active control algorithm specifically tailored to the system＇s tmique damping characteristics. To demonstrate the effectiveness of the VAD-damper system for adaptive base-isolation, numerical simulations are conducted for three and seven-story base-isolated buildings subject to both far and near-field ground motions. The results indicate that the system can achieve significant reductions in response compared to the base-isolated buildings with no damper. The proposed system is also found to perform well compared to a typical semi-active damper.展开更多
Adopting a soft site model built on soft interlayer soil foundation,a shaking table test for soft interlayer soil-isolated structure interaction is conducted to investigate the seismic response of isolated structure o...Adopting a soft site model built on soft interlayer soil foundation,a shaking table test for soft interlayer soil-isolated structure interaction is conducted to investigate the seismic response of isolated structure on soft site,and analyze its isolation effect.Test results show that the test can reflect the earthquake response characteristics of isolated structure on soft site.It is on soft site that the dynamic characteristics of isolated structure,acceleration magnification factor(AMF)of isolated structure and isolation efficiency of the isolation layer differ from those on rigid foundation with an soil-structure interaction(SSI)effect,represented by the reduction in fundamental vibration frequency of isolated structure and the increase of damping ratio with changes of the SSI effect.SSI can either increase or decrease AMF of isolated structure on soft site,depending on the characteristics of earthquake motion input.Furthermore,the isolation efficiency of isolation layer on soft site is decreased with the SSI effect,which is related to the peak ground acceleration(PGA)and the characteristics of earthquake motion input.展开更多
The key points to consider in determining the effectiveness of using structural isolation with shape memory alloys （SMA） are the constitutive model, the SMA isolation device and the analysis method. In this paper, a...The key points to consider in determining the effectiveness of using structural isolation with shape memory alloys （SMA） are the constitutive model, the SMA isolation device and the analysis method. In this paper, a simplified constitutive model based on the classic theory of plasticity is proposed to simulate the behavior of the superelasticity of the SMA, in which the martensite volume fraction is considered as one of the state variables. Comparisons between simulation results and experimental results are made and indicate that the proposed constitutive model yields stress-strain curves that are in good agreement with the experimental ones. Thus, the proposed model can correctly simulate the yield mechanism and energy dissipation capacity of the SMA. Next, in order to make full use of the superelasticity of SMA, a new SMA isolator composed of pre-tensioned SMA bars is presented. Then, a finite element analytical model is established to simulate the behavior of the SMA isolator according to its configuration and simplified constitutive model. Finally, a simplified design method for long-span structures installed with SMA isolators is proposed, which is further used to investigate the isolation effects of a space grid structure. Results show that the SMA isolator can reduce the seismic responses of the structure effectively, which indicates the effectiveness of the proposed SMA isolation method.展开更多
The title compound 9S,9aS-neotuberostemonine （1） was isolated from the 95%ethanol extract of the roots of Stemona tuberosa. The crystal structure of 1, C22H33NO4, wasdetermined by single-crystal X-ray diffraction an...The title compound 9S,9aS-neotuberostemonine （1） was isolated from the 95%ethanol extract of the roots of Stemona tuberosa. The crystal structure of 1, C22H33NO4, wasdetermined by single-crystal X-ray diffraction analysis. The crystal belongs to orthorhombicsystem, space group P212121, with a-9.0115（11）, b = 10.612（4）, c = 22.074（3） A, V= 2110.9（8）S^3, Z= 4, Mr= 375.49, Dc= 1.182 g/cm3, λ= 0.71079 A,μ= 0.080 cm^-1, F（000） = 816, S = 1.019,R = 0.0579 and wR = 0.1358. A total of 3109 unique reflections were collected, of which 2902were observed （I〉 2σ（I））. The absolute configuration of 1 could be assigned by referring to theconserved configuration of the methyl groups at C（13） and C（20）. In the solid state, the moleculeswere linked into a chain along the a-axis through weak hydrogen bond C（ll）-H（11A）…O（2）.Compound 1 shows significant inhibition of cough by 24%, 44% and 65% at doses of 50, 100 and150 mg/kg, respectively.展开更多
In industrial processes,there exist faults that have complex effect on process variables.Complex and simple faults are defined according to their effect dimensions.The conventional approaches based on structured resid...In industrial processes,there exist faults that have complex effect on process variables.Complex and simple faults are defined according to their effect dimensions.The conventional approaches based on structured residuals cannot isolate complex faults.This paper presents a multi-level strategy for complex fault isolation.An extraction procedure is employed to reduce the complex faults to simple ones and assign them to several levels.On each level,faults are isolated by their different responses in the structured residuals.Each residual is obtained insensitive to one fault but more sensitive to others.The faults on different levels are verified to have different residual responses and will not be confused.An entire incidence matrix containing residual response characteristics of all faults is obtained,based on which faults can be isolated.The proposed method is applied in the Tennessee Eastman process example,and the effectiveness and advantage are demonstrated.展开更多
The method of collaborative work between steel plate anti-wind bearing(AWB) and rubber isolation bearing is proposed to study the vibration reduction effect of isolation structure under stronger wind load,and the func...The method of collaborative work between steel plate anti-wind bearing(AWB) and rubber isolation bearing is proposed to study the vibration reduction effect of isolation structure under stronger wind load,and the function mechanism is explained.Based on a practical project,three kinds of schemes with different isolation layers are put forward,the finite element software ETABS is used for time history analysis,and comparison is made on the seismic response of different isolated structure and aseismic structure.Comparison result shows that the isolation layer with rubber bearing and AWB can work reasonably,but further optimization on the designed parameters is needed.Moreover,the design value of horizontal bearing capacity of lead rubber bearing(LRB) is appropriate to be close to the seismic isolation layer under wind load excitation.Finally,numerical simulation and comparative analysis of shear test of the AWB are conducted.With a very small yield displacement and yield strength over 80% of the set of horizontal bearing capacity,the AWB is validated to satisfy the working conditions which provide the horizontal bearing capacity under normal operating conditions and designed earthquake.The AWB yields and malfunctions,when the maximum displacement is less than the displacement of the isolation layer.展开更多
Three novel interesting polychlorinated cyclodipeptides,designated dyssmide A(1),B(2),C(3)and a known compound,2,3-dihydrodyeamide C(4)were isolated from the sponge Dysidea sp.Their structures were elucidated by spect...Three novel interesting polychlorinated cyclodipeptides,designated dyssmide A(1),B(2),C(3)and a known compound,2,3-dihydrodyeamide C(4)were isolated from the sponge Dysidea sp.Their structures were elucidated by spectroscopic methods.展开更多
A new prenylated flavonol, maackiaflavonol, was isolated from the ethanol extract of the roots of Maackia tenuifolia. Its structure was elucidated as 7-hydrox-8-prenylflavonol by means of spectroscopic analysis (UV, I...A new prenylated flavonol, maackiaflavonol, was isolated from the ethanol extract of the roots of Maackia tenuifolia. Its structure was elucidated as 7-hydrox-8-prenylflavonol by means of spectroscopic analysis (UV, IR, MS, NMR and 1H-1H COSY) and confirmed by total synthesis.展开更多
A novel and unusual sterol with unsaturation in the△^(5(14)) position,5α-cholesta-8(14),24(25)-diene-3β,6α-diol 1,was isolated from the South China Ses sponge Dysidea sp.The structure and relative stereochemistry ...A novel and unusual sterol with unsaturation in the△^(5(14)) position,5α-cholesta-8(14),24(25)-diene-3β,6α-diol 1,was isolated from the South China Ses sponge Dysidea sp.The structure and relative stereochemistry of 1 was established by spectral analysis and comparison to the spectral data of known sterols.展开更多
Base isolation is one of the most promising alternatives among the structure control methods.In recent decades,base isolation has been seriously considered for civil structures,such as buildings and bridges,subjected ...Base isolation is one of the most promising alternatives among the structure control methods.In recent decades,base isolation has been seriously considered for civil structures,such as buildings and bridges,subjected to ground motion.The research achievements and development of seismic base isolation technique for civil structures in Huazhong University of Science and Technology(HUST)are introduced.The achievements include project applications,experimental research results and theoretical innovation.展开更多
A design procedure for improving the seismic performance of unequal-span underground structures by installing isolation devices at the top end of columns is proposed based on the seismic failure mode of frame-type und...A design procedure for improving the seismic performance of unequal-span underground structures by installing isolation devices at the top end of columns is proposed based on the seismic failure mode of frame-type underground structures and the design concept of critical support columns.A two-dimensional finite element model(FEM)for a soil-underground structure with an unequal-span interaction system was established to shed light on the effects of a complex subway station with elastic sliding bearings(ESB)and lead rubber bearings(LRB)on seismic mitigation.It was found that the stiffness and internal force distribution of the underground structure changed remarkably with the installation of isolation devices at the top end of the columns.The constraints of the beam-column joints were significantly weakened,resulting in a decrease in the overall lateral stiffness and an increase in the structural lateral displacement.The introduction of the isolation device effectively reduces the internal force and seismic damage of the frame column;however,the tensile damage to the isolation structure,such as the roof,bottom plate,and sidewall,significantly increased compared to those of the non-isolation structure.Although the relative slip of the ESB remains within a controllable range under strong earthquake excitation as well as frame columns with stable vertical support and self-restoration functions,the LRB shows a better performance during seismic failure and better lateral displacement response of the unequal-span underground structure.The analysis results provide new ideas and references for promoting the application of seismic isolation technology in underground structures.展开更多
The title compound, 4β,6α,9α-trimethy-2-carboxyltricyclo[6.3.0.0^（4,5）]undec-2-ene, is a sesquiterpene which was first isolated from Ligularia caloxantha and characterized by MS and NMR. In addition, the structur...The title compound, 4β,6α,9α-trimethy-2-carboxyltricyclo[6.3.0.0^（4,5）]undec-2-ene, is a sesquiterpene which was first isolated from Ligularia caloxantha and characterized by MS and NMR. In addition, the structure was determined by X-ray single-crystal diffraction. It crystallizes in orthorhombie, space group P212121 with a = 8.197（2）, b = 14.876（3）, c = 22.281（6） A, α = β = γ = 90°, V = 2716.9（11） ]A^3, Z = 8, C15H22O2, Mr = 234.34, Dc = 1.146 g/cm^3, μ（MoKa） = 0.074 mm^-1, F（000） = 1024, the final R = 0.0384 and wR = 0.0856 for 6200 independent reflections （Rint = 0.066） and 2538 observed ones （I 〉 2σ（I））. In the molecule, there are three fused five-membered rings; while in this crystal form, the asymmetric unit contains two molecules of the same hand and they are linked together by two intermolecular O-H...O hydrogen bonds to form a dimer.展开更多
Chemical vapor deposition is considered as the most hopeful method for the synthesis of large-area high-quality hexagonal boron nitride on the substrate of catalytic metal. However, the size the hexagonal boron nitrid...Chemical vapor deposition is considered as the most hopeful method for the synthesis of large-area high-quality hexagonal boron nitride on the substrate of catalytic metal. However, the size the hexagonal boron nitride films are limited to the size of growth chamber, which indicates a lower production efficiency. In this paper, the utilization efficiency of growth chamber is highly improved by alternately stacking multiple pieces of Cu foils and carbon fiber surface felt with porous structure. Uniform and continuous hexagonal boron nitride films are prepared on Cu foils through chemical vapor deposition utilizing ammonia borane as the precursor. This work develops a simple and practicable method for high-throughput preparation of hexagonal boron nitride films, which could contribute to the industrial application of hexagonal boron nitride. .展开更多
A new polysaccharide,GBW was obtained homogeneous as determined by HPLC from the roots of Glycyrrhizia uralensis Fisch. The molecular weight was estimated to be 4000. The component sugar was identified as glucose only...A new polysaccharide,GBW was obtained homogeneous as determined by HPLC from the roots of Glycyrrhizia uralensis Fisch. The molecular weight was estimated to be 4000. The component sugar was identified as glucose only. The specific rotation [α]^(28)_D (C=0.1,H_2O) was +1200. The α-configuration was established by IR and ^(13)C NMR. Methylation analysis, periodate oxidation, Smith degradation, partial hydrolysis, KI-I_2 reaction and ^(13)C NMR showed that GBW is a new (1→4)linked linear α-D-glucan. The structure is shown as 1.展开更多
A new Mutactimycin group antibiotic(XF-1)was isolated from the mycelium of Streptomyces sp.80-115 and its structure has been determined on the basis of its spectroscopical and chemical properties. XF-1 showed active a...A new Mutactimycin group antibiotic(XF-1)was isolated from the mycelium of Streptomyces sp.80-115 and its structure has been determined on the basis of its spectroscopical and chemical properties. XF-1 showed active against some Gram positive bacteria.展开更多
文摘A novel radiation tolerant SOI isolation structure,consisting of thin SiO2/polysilicon/field SiO2 multilayers,is proposed. A device with this structure does not show obvious changes in subthreshold characteristics and leakage current,indicating a superior radiation tolerance to traditional LOCOS.
基金National Natural Science Foundation of China Under Grand No.50778006Funding Project for Academic Human Resources Development in Institutions of Higher Learning Under the Jurisdiction of Beijing Municipality
文摘A theoretical model of a friction pendulum system （FPS） is introduced to examine its application for the seismic isolation of spatial lattice shell structures. An equation of motion of the lattice shell with FPS bearings is developed. Then, seismic isolation studies are performed for both double-layer and single-layer lattice shell structures under different seismic input and design parameters of the FPS. The influence of frictional coefficients and radius of the FPS on seismic performance are discussed. Based on the study, some suggestions for seismic isolation design of lattice shells with FPS bearings are given and conclusions are made which could be helpful in the application of FPS.
基金supported by the National Key R&D Program of China(2022YFC3501805)the Science and Technology Program of Tianjin in China(23ZYJDSS00030)+2 种基金the National Natural Science Foundation of China(82374030)the Science&Technology Development Fund of Tianjin Education Commission for Higher Education(2021KJ127)Tianjin Outstanding Youth Fund(23JCJQJC00030).
文摘Panax notoginseng is a traditional Chinese medicine containing various constituents,including the saponins,polysaccharides,polyacetylenes,amino acids,etc.It has beneficial functions,such as the anti-inflammatory,antitumor,hepatoprotective,and anti-aging effects.Among these,P.notoginseng polysaccharides(PNPs)have been exploited because of their extensive pharmacological effects,being ranked as one of the current research hotspots,especially for the functional foods and medical practice.In this review,the literature related to PNPs in the past 20 years was surveyed and analyzed using both the China National Knowledge Infrastructure(CNKI)and Web of Science(WOS)databases.The visualization diagram shows that current studies on PNPs mainly focus on the antioxidant and immunomodulatory activities and structural characterization.In addition,the extraction,separation,purification,chemical analysis,structural characteristics,bioactivities,and applications of PNPs are outlined,in detail,aimed to provide valuable information for the further study,development,and utilization regarding PNPs.
基金National Natural Science Foundation of China under Grant No.52278490。
文摘Finding an optimal isolator arrangement for asymmetric structures using traditional conceptual design methods that can significantly minimize torsional response while ensuring efficient horizontal seismic isolation is cumbersome and inefficient.Thus,this work develops a multi-objective optimization method to enhance the torsional resistance of asymmetric base-isolated structures.The primary objective is to simultaneously minimize the interstory rotation of the superstructure,the rotation of the isolation layer,and the interstory displacement of the superstructure without exceeding the isolator displacement limits.A fast non-dominated sorting genetic algorithm(NSGA-Ⅱ)is employed to satisfy this optimization objective.Subsequently,the isolator arrangement,encompassing both positions and categories,is optimized according to this multi-objective optimization method.Additionally,an optimization design platform is developed to streamline the design operation.This platform integrates the input of optimization parameters,the output of optimization results,the finite element analysis,and the multi-objective optimization method proposed herein.Finally,the application of this multi-objective optimization method and its associated platform are demonstrated on two asymmetric base-isolated structures of varying heights and plan configurations.The results indicate that the optimal isolator arrangement derived from the optimization method can further improve the control over the lateral and torsional responses of asymmetric base-isolated structures compared to conventional conceptual design methods.Notably,the interstory rotation of the optimal base-isolated structure is significantly reduced,constituting only approximately 33.7%of that observed in the original base-isolated structure.The proposed platform facilitates the automatic generation of the optimal design scheme for the isolators of asymmetric base-isolated structures,offering valuable insights and guidance for the burgeoning field of intelligent civil engineering design.
文摘Semi-active dampers are used in base-isolation to reduce the seismic response of civil engineering structures. In the present study, a new semi-active damping system using variable amplification will be investigated for adaptive baseisolation. It uses a novel variable amplification device （VAD） connected in series with a passive damper. The VAD is capable of producing multiple amplification factors, each corresponding to a different amplification state. Forces from the damper are amplified to the structure according to the current amplification state, which is selected via a semi-active control algorithm specifically tailored to the system＇s tmique damping characteristics. To demonstrate the effectiveness of the VAD-damper system for adaptive base-isolation, numerical simulations are conducted for three and seven-story base-isolated buildings subject to both far and near-field ground motions. The results indicate that the system can achieve significant reductions in response compared to the base-isolated buildings with no damper. The proposed system is also found to perform well compared to a typical semi-active damper.
基金supported by the Jiangsu Natural Science Foundation of China(Grant No.BK2012477)the Science Research Foundation of Nanjing Institute of Technology(CKJA201505,JCYJ201618)
文摘Adopting a soft site model built on soft interlayer soil foundation,a shaking table test for soft interlayer soil-isolated structure interaction is conducted to investigate the seismic response of isolated structure on soft site,and analyze its isolation effect.Test results show that the test can reflect the earthquake response characteristics of isolated structure on soft site.It is on soft site that the dynamic characteristics of isolated structure,acceleration magnification factor(AMF)of isolated structure and isolation efficiency of the isolation layer differ from those on rigid foundation with an soil-structure interaction(SSI)effect,represented by the reduction in fundamental vibration frequency of isolated structure and the increase of damping ratio with changes of the SSI effect.SSI can either increase or decrease AMF of isolated structure on soft site,depending on the characteristics of earthquake motion input.Furthermore,the isolation efficiency of isolation layer on soft site is decreased with the SSI effect,which is related to the peak ground acceleration(PGA)and the characteristics of earthquake motion input.
基金National Natural Science Foundation of China Under Grant No. 50725828 & No. 50808041Scientific Research Foundation of Graduate School of Southeast University Under Grant No. YBJJ1006Teaching and Research Foundation for Excellent Young Teacher of Southeast University
文摘The key points to consider in determining the effectiveness of using structural isolation with shape memory alloys （SMA） are the constitutive model, the SMA isolation device and the analysis method. In this paper, a simplified constitutive model based on the classic theory of plasticity is proposed to simulate the behavior of the superelasticity of the SMA, in which the martensite volume fraction is considered as one of the state variables. Comparisons between simulation results and experimental results are made and indicate that the proposed constitutive model yields stress-strain curves that are in good agreement with the experimental ones. Thus, the proposed model can correctly simulate the yield mechanism and energy dissipation capacity of the SMA. Next, in order to make full use of the superelasticity of SMA, a new SMA isolator composed of pre-tensioned SMA bars is presented. Then, a finite element analytical model is established to simulate the behavior of the SMA isolator according to its configuration and simplified constitutive model. Finally, a simplified design method for long-span structures installed with SMA isolators is proposed, which is further used to investigate the isolation effects of a space grid structure. Results show that the SMA isolator can reduce the seismic responses of the structure effectively, which indicates the effectiveness of the proposed SMA isolation method.
基金supported by Guangdong Key Scientific Project(2013A022100029)Zhongshan Scientific Scheme(2017B1134)
文摘The title compound 9S,9aS-neotuberostemonine （1） was isolated from the 95%ethanol extract of the roots of Stemona tuberosa. The crystal structure of 1, C22H33NO4, wasdetermined by single-crystal X-ray diffraction analysis. The crystal belongs to orthorhombicsystem, space group P212121, with a-9.0115（11）, b = 10.612（4）, c = 22.074（3） A, V= 2110.9（8）S^3, Z= 4, Mr= 375.49, Dc= 1.182 g/cm3, λ= 0.71079 A,μ= 0.080 cm^-1, F（000） = 816, S = 1.019,R = 0.0579 and wR = 0.1358. A total of 3109 unique reflections were collected, of which 2902were observed （I〉 2σ（I））. The absolute configuration of 1 could be assigned by referring to theconserved configuration of the methyl groups at C（13） and C（20）. In the solid state, the moleculeswere linked into a chain along the a-axis through weak hydrogen bond C（ll）-H（11A）…O（2）.Compound 1 shows significant inhibition of cough by 24%, 44% and 65% at doses of 50, 100 and150 mg/kg, respectively.
基金Supported by the National Natural Science Foundation of China(60574047)the National High Technology Research and Development Program of China(2007AA04Z168,2009AA04Z154)the Research Fund for the Doctoral Program of Higher Education in China(20050335018)
文摘In industrial processes,there exist faults that have complex effect on process variables.Complex and simple faults are defined according to their effect dimensions.The conventional approaches based on structured residuals cannot isolate complex faults.This paper presents a multi-level strategy for complex fault isolation.An extraction procedure is employed to reduce the complex faults to simple ones and assign them to several levels.On each level,faults are isolated by their different responses in the structured residuals.Each residual is obtained insensitive to one fault but more sensitive to others.The faults on different levels are verified to have different residual responses and will not be confused.An entire incidence matrix containing residual response characteristics of all faults is obtained,based on which faults can be isolated.The proposed method is applied in the Tennessee Eastman process example,and the effectiveness and advantage are demonstrated.
基金the National Natural Science Foundation of China(No.51578160)
文摘The method of collaborative work between steel plate anti-wind bearing(AWB) and rubber isolation bearing is proposed to study the vibration reduction effect of isolation structure under stronger wind load,and the function mechanism is explained.Based on a practical project,three kinds of schemes with different isolation layers are put forward,the finite element software ETABS is used for time history analysis,and comparison is made on the seismic response of different isolated structure and aseismic structure.Comparison result shows that the isolation layer with rubber bearing and AWB can work reasonably,but further optimization on the designed parameters is needed.Moreover,the design value of horizontal bearing capacity of lead rubber bearing(LRB) is appropriate to be close to the seismic isolation layer under wind load excitation.Finally,numerical simulation and comparative analysis of shear test of the AWB are conducted.With a very small yield displacement and yield strength over 80% of the set of horizontal bearing capacity,the AWB is validated to satisfy the working conditions which provide the horizontal bearing capacity under normal operating conditions and designed earthquake.The AWB yields and malfunctions,when the maximum displacement is less than the displacement of the isolation layer.
基金Supported by the National Natural Science Foundation the State Education Committee Of China
文摘Three novel interesting polychlorinated cyclodipeptides,designated dyssmide A(1),B(2),C(3)and a known compound,2,3-dihydrodyeamide C(4)were isolated from the sponge Dysidea sp.Their structures were elucidated by spectroscopic methods.
文摘A new prenylated flavonol, maackiaflavonol, was isolated from the ethanol extract of the roots of Maackia tenuifolia. Its structure was elucidated as 7-hydrox-8-prenylflavonol by means of spectroscopic analysis (UV, IR, MS, NMR and 1H-1H COSY) and confirmed by total synthesis.
文摘A novel and unusual sterol with unsaturation in the△^(5(14)) position,5α-cholesta-8(14),24(25)-diene-3β,6α-diol 1,was isolated from the South China Ses sponge Dysidea sp.The structure and relative stereochemistry of 1 was established by spectral analysis and comparison to the spectral data of known sterols.
基金funded by the National Natural Science Foundation of China(Grant No:50925828 and 50778077)
文摘Base isolation is one of the most promising alternatives among the structure control methods.In recent decades,base isolation has been seriously considered for civil structures,such as buildings and bridges,subjected to ground motion.The research achievements and development of seismic base isolation technique for civil structures in Huazhong University of Science and Technology(HUST)are introduced.The achievements include project applications,experimental research results and theoretical innovation.
基金the research funding provided by the National Natural Science Foundation of China(NSFC,No.51978333)the SINOMACH Science and Technology Major Project(SINOMAST-ZDZX-2020-03)。
文摘A design procedure for improving the seismic performance of unequal-span underground structures by installing isolation devices at the top end of columns is proposed based on the seismic failure mode of frame-type underground structures and the design concept of critical support columns.A two-dimensional finite element model(FEM)for a soil-underground structure with an unequal-span interaction system was established to shed light on the effects of a complex subway station with elastic sliding bearings(ESB)and lead rubber bearings(LRB)on seismic mitigation.It was found that the stiffness and internal force distribution of the underground structure changed remarkably with the installation of isolation devices at the top end of the columns.The constraints of the beam-column joints were significantly weakened,resulting in a decrease in the overall lateral stiffness and an increase in the structural lateral displacement.The introduction of the isolation device effectively reduces the internal force and seismic damage of the frame column;however,the tensile damage to the isolation structure,such as the roof,bottom plate,and sidewall,significantly increased compared to those of the non-isolation structure.Although the relative slip of the ESB remains within a controllable range under strong earthquake excitation as well as frame columns with stable vertical support and self-restoration functions,the LRB shows a better performance during seismic failure and better lateral displacement response of the unequal-span underground structure.The analysis results provide new ideas and references for promoting the application of seismic isolation technology in underground structures.
文摘The title compound, 4β,6α,9α-trimethy-2-carboxyltricyclo[6.3.0.0^（4,5）]undec-2-ene, is a sesquiterpene which was first isolated from Ligularia caloxantha and characterized by MS and NMR. In addition, the structure was determined by X-ray single-crystal diffraction. It crystallizes in orthorhombie, space group P212121 with a = 8.197（2）, b = 14.876（3）, c = 22.281（6） A, α = β = γ = 90°, V = 2716.9（11） ]A^3, Z = 8, C15H22O2, Mr = 234.34, Dc = 1.146 g/cm^3, μ（MoKa） = 0.074 mm^-1, F（000） = 1024, the final R = 0.0384 and wR = 0.0856 for 6200 independent reflections （Rint = 0.066） and 2538 observed ones （I 〉 2σ（I））. In the molecule, there are three fused five-membered rings; while in this crystal form, the asymmetric unit contains two molecules of the same hand and they are linked together by two intermolecular O-H...O hydrogen bonds to form a dimer.
文摘Chemical vapor deposition is considered as the most hopeful method for the synthesis of large-area high-quality hexagonal boron nitride on the substrate of catalytic metal. However, the size the hexagonal boron nitride films are limited to the size of growth chamber, which indicates a lower production efficiency. In this paper, the utilization efficiency of growth chamber is highly improved by alternately stacking multiple pieces of Cu foils and carbon fiber surface felt with porous structure. Uniform and continuous hexagonal boron nitride films are prepared on Cu foils through chemical vapor deposition utilizing ammonia borane as the precursor. This work develops a simple and practicable method for high-throughput preparation of hexagonal boron nitride films, which could contribute to the industrial application of hexagonal boron nitride. .
文摘A new polysaccharide,GBW was obtained homogeneous as determined by HPLC from the roots of Glycyrrhizia uralensis Fisch. The molecular weight was estimated to be 4000. The component sugar was identified as glucose only. The specific rotation [α]^(28)_D (C=0.1,H_2O) was +1200. The α-configuration was established by IR and ^(13)C NMR. Methylation analysis, periodate oxidation, Smith degradation, partial hydrolysis, KI-I_2 reaction and ^(13)C NMR showed that GBW is a new (1→4)linked linear α-D-glucan. The structure is shown as 1.
文摘A new Mutactimycin group antibiotic(XF-1)was isolated from the mycelium of Streptomyces sp.80-115 and its structure has been determined on the basis of its spectroscopical and chemical properties. XF-1 showed active against some Gram positive bacteria.
