Leaf-color mutations are a widely-observed class of mutations, playing an important role in the study of chlorophyll biosynthesis and plant chloroplast structure, function, genetics and development. A naturally-occurr...Leaf-color mutations are a widely-observed class of mutations, playing an important role in the study of chlorophyll biosynthesis and plant chloroplast structure, function, genetics and development. A naturally-occurring leaf-color rice mutant, Baihuaidao 7, was analyzed. Mutant plants typically exhibited a green-white-green leaf-color progression, but this phenotype was only expressed in the presence of a stress signal induced by mechanical scarification such as transplantation. Prior to the appearance of white ~eaves, mutant plant growth, leaf color, chlorophyll content, and chloroplast ultrastructure appeared to be identical to those of the wild type. After the changeover to white leaf color, an examination of the mutated leaves revealed a decrease in total chlorophyll, chlorophyll a, chlorophyll b, and carotenoid content, a reduction in the number of chloroplast grana lamella and grana, and a gradual degradation of the thylakoid lamellas. At maturity, the mutant plant was etiolated and dwarfed compared with wild-type plants. Genetic analysis indicated that the leaf mutant character is controlled by a recessive nuclear gene. Genetic mapping of the mutant gene was performed using an F2 population derived from a Baihuaidao 7 ~ Jiangxi 1587 cross. The mutant gene was mapped to rice chromosome 11, positioned between InDel markers L59.2-7 and L64.8-11, which are separated by approximately 740.5 kb. The mutant gene is believed to be a new leaf-color mutant gene in rice, and is tentatively designated as gwgl.展开更多
Neural stem cells,which are capable of multi-potential differentiation and self-renewal,have recently been shown to have clinical potential for repairing central nervous system tissue damage.However,the theme trends a...Neural stem cells,which are capable of multi-potential differentiation and self-renewal,have recently been shown to have clinical potential for repairing central nervous system tissue damage.However,the theme trends and knowledge structures for human neural stem cells have not yet been studied bibliometrically.In this study,we retrieved 2742 articles from the PubMed database from 2013 to 2018 using "Neural Stem Cells" as the retrieval word.Co-word analysis was conducted to statistically quantify the characteristics and popular themes of human neural stem cell-related studies.Bibliographic data matrices were generated with the Bibliographic Item Co-Occurrence Matrix Builder.We identified 78 high-frequency Medical Subject Heading(MeSH)terms.A visual matrix was built with the repeated bisection method in gCLUTO software.A social network analysis network was generated with Ucinet 6.0 software and GraphPad Prism 5 software.The analyses demonstrated that in the 6-year period,hot topics were clustered into five categories.As suggested by the constructed strategic diagram,studies related to cytology and physiology were well-developed,whereas those related to neural stem cell applications,tissue engineering,metabolism and cell signaling,and neural stem cell pathology and virology remained immature.Neural stem cell therapy for stroke and Parkinson’s disease,the genetics of microRNAs and brain neoplasms,as well as neuroprotective agents,Zika virus,Notch receptor,neural crest and embryonic stem cells were identified as emerging hot spots.These undeveloped themes and popular topics are potential points of focus for new studies on human neural stem cells.展开更多
A physical value mapping (PVM) algorithm based on finite element mesh from the stamped part in stamping process to the product is presented, In order to improve the efficiency of the PVM algorithm, a search way from...A physical value mapping (PVM) algorithm based on finite element mesh from the stamped part in stamping process to the product is presented, In order to improve the efficiency of the PVM algorithm, a search way from the mesh of the product to the mesh of the stamped part will be adopted. At the same time, the search process is divided into two steps: entire search (ES) and local search (LS), which improve the searching efficiency. The searching area is enlarged to avoid missing projection elements in ES process. An arc-length method is introduced in LS process. The validity is confirmed by the results of the complex industry-forming product.展开更多
Faults and fractures of multiple scales are frequently induced and generated in compressional structural system. Comprehensive identification of these potential faults and fractures that cannot be distinguished direct...Faults and fractures of multiple scales are frequently induced and generated in compressional structural system. Comprehensive identification of these potential faults and fractures that cannot be distinguished directly from seismic profile of the complex structures is still an unanswered problem. Based on the compressional structural geometry and kinematics theories as well as the structural interpretation from seismic data, a set of techniques is established for the identification of potential faults and fractures in compressional structures. Firstly, three-dimensional(3D) patterns and characteristics of the faults directly interpreted from seismic profile were illustrated by 3D structural model. Then, the unfolding index maps, the principal structural curvature maps, and tectonic stress field maps were obtained from structural restoration. Moreover, potential faults and fractures in compressional structures were quantitatively identified relying on comprehensive analysis of these three maps. Successful identification of the potential faults and fractures in Mishrif limestone formation and in Asmari dolomite formation of Buzurgan anticline in Iraq demonstrates the applicability and reliability of these techniques.展开更多
Taking autonomous driving and driverless as the research object,we discuss and define intelligent high-precision map.Intelligent high-precision map is considered as a key link of future travel,a carrier of real-time p...Taking autonomous driving and driverless as the research object,we discuss and define intelligent high-precision map.Intelligent high-precision map is considered as a key link of future travel,a carrier of real-time perception of traffic resources in the entire space-time range,and the criterion for the operation and control of the whole process of the vehicle.As a new form of map,it has distinctive features in terms of cartography theory and application requirements compared with traditional navigation electronic maps.Thus,it is necessary to analyze and discuss its key features and problems to promote the development of research and application of intelligent high-precision map.Accordingly,we propose an information transmission model based on the cartography theory and combine the wheeled robot’s control flow in practical application.Next,we put forward the data logic structure of intelligent high-precision map,and analyze its application in autonomous driving.Then,we summarize the computing mode of“Crowdsourcing+Edge-Cloud Collaborative Computing”,and carry out key technical analysis on how to improve the quality of crowdsourced data.We also analyze the effective application scenarios of intelligent high-precision map in the future.Finally,we present some thoughts and suggestions for the future development of this field.展开更多
"Synthetic"allopolyploids recreated by interspecific hybridization play an important role in providing novel genomic variation for crop improvement.Such synthetic allopolyploids often undergo rapid genomic s..."Synthetic"allopolyploids recreated by interspecific hybridization play an important role in providing novel genomic variation for crop improvement.Such synthetic allopolyploids often undergo rapid genomic structural variation(SV).However,how such SV arises,is inherited and fixed,and how it affects important traits,has rarely been comprehensively and quantitively studied in advanced generation synthetic lines.A better understanding of these processes will aid breeders in knowing how to best utilize synthetic allopolyploids in breeding programs.Here,we analyzed three genetic mapping populations(735 DH lines)derived from crosses between advanced synthetic and conventional Brassica napus(rapeseed)lines,using whole-genome sequencing to determine genome composition.We observed high tolerance of large structural variants,particularly toward the telomeres,and preferential selection for balanced homoeologous exchanges(duplication/deletion events between the A and C genomes resulting in retention of gene/chromosome dosage between homoeologous chromosome pairs),including stable events involving whole chromosomes("pseudoeuploidy").Given the experimental design(all three populations shared a common parent),we were able to observe that parental SV was regularly inherited,showed genetic hitchhiking effects on segregation,and was one of the major factors inducing adjacent novel and larger SV.Surprisingly,novel SV occurred at low frequencies with no significant impacts on observed fertility and yield-related traits in the advanced generation synthetic lines.However,incorporating genome-wide SV in linkage mapping explained significantly more genetic variance for traits.Our results provide a framework for detecting and understanding the occurrence and inheritance of genomic SV in breeding programs,and support the use of synthetic parents as an important source of novel trait variation.展开更多
Five-fold twinned nanostructures are intrinsically strained or relaxed by extended defects to satisfy the space-filling requirement.Although both of metallic and semiconductor five-fold twinned nanostructures show inh...Five-fold twinned nanostructures are intrinsically strained or relaxed by extended defects to satisfy the space-filling requirement.Although both of metallic and semiconductor five-fold twinned nanostructures show inhomogeneity in their cross-sectional strain distribution,the evident strain concentration at twin boundaries in the semiconductor systems has been found in contrast to the metallic systems.Naturally,a problem is raised how the chemical bonding characteristics of various five-fold twinned nanosystems affects their strain-relieving defect structures.Here using three-dimensional(3D)electron diffraction mapping methodology,the intrinsic strain and the strain-relieving defects in a pentagonal Ag nanowire and a star-shaped boron carbide nanowire,both of them have basically equal radial twin-plane width about 30 nm,are nondestructively characterized.The non-uniform strain and defect distribution between the five single crystalline segments are found in both of the five-fold twinned nanowires.Diffraction intensity fine structure analysis for the boron carbide five-fold twinned nanowire indicates the presence of high-density of planar defects which are responsible for the accommodation of the intrinsic angular excess.However,for the Ag five-fold twinned nanowire,the star-disclination strain field is still present,although is partially relieved by the formation of localized stacking fault layers accompanied by partial dislocations.Energetic analysis suggests that the variety in the strain-relaxation ways for the two types of five-fold twinned nanowires could be ascribed to the large difference in shear modulus between the soft noble metal Ag and the superhard covalent compound boron carbide.展开更多
In order to solve the problem of substantial computational resources of lattice structure during optimization, a local relative density mapping(LRDM) method is proposed. The proposed method uses solid isotropic micros...In order to solve the problem of substantial computational resources of lattice structure during optimization, a local relative density mapping(LRDM) method is proposed. The proposed method uses solid isotropic microstructures with penalization to optimize a model at the macroscopic scale. The local relative density information is obtained from the topology optimization result. The contour lines of an optimized model are extracted using a density contour approach, and the triangular mesh is generated using a mesh generator. A local mapping relationship between the elements’ relative density and the struts’ relative cross?sectional area is established to automatically determine the diameter of each individual strut in the lattice structures. The proposed LRDM method can be applied to local finite element meshes and local density elements, but it is also suitable for global ones. In addition, some cases are con?sidered in order to test the e ectiveness of the LRDM method. The results show that the solution time of the LRDM is lower than the RDM method by approximately 50%. The proposed method provides instructions for the design of more complex lattice structures.展开更多
The first important problem in the star forming process is the formation of proto star core in star forming regions of molecular cloud. The multi core structure in star forming regions is related to the forming of pro...The first important problem in the star forming process is the formation of proto star core in star forming regions of molecular cloud. The multi core structure in star forming regions is related to the forming of proto star core. The molecular radiation of C 18 O( J = 1-0) in Cepheus C has been observed. The C 18 O( J = 1-0) observations form the basis for an interesting study on the cloud cores and star formation activity in the cores of the Cepheus C. In order to study the multi core structure of C 18 O( J = 1-0) in the Cepheus C the channel maps and the position velocity diagrams of C 18 O( J = 1-0) will be shown. From the maps it is found that the contour level and distribution size of the three cores in Cepheus C are related to the channel velocity very much. The channel velocity of C 18 O( J = 1-0) molecules in core b, which distributed in all the channels velocity, is different with one in core a and core c very much. The C 18 O( J = 1-0) molecules in core a and core c of the Cepheus C mostly distributed in the blue shifted channel velocity relating to peak velocity, and only in -10.0 ~ -9.5 km/s, which is the red shifted channel velocity relating to peak velocity. And the contour level of C 18 O( J = 1-0) in -10.0 ~ -9.5 km/s is small and the distrbution size in the channel map is small. According to the position velocity diagrams the asymmetry of the distribution both blue shifted and red shifted components should reflect the asymmetry of the profile. From the diagrams it also is found that the contour level and the distribution size of the three cores are different from each other. Both results from the maps and diagrams are coincident with each other.展开更多
The cell mechanical features are largely regulated by actin cytokeleton. By analyzing the mechanical features, it is possible to evaluate the characteristics of the complicated actin cytoskeleton in diverse cell types...The cell mechanical features are largely regulated by actin cytokeleton. By analyzing the mechanical features, it is possible to evaluate the characteristics of the complicated actin cytoskeleton in diverse cell types. In this study, we examined the sub-membrane mechanical structures of normal fibroblasts TIG-1 cells, and cervical cancer Hela cells using local elasticity mapping method of atomic force microscope. Especially we aimed at clarifying the regulatory mechanisms of sub-membrane actin structures in these cells by activation of actomyosin formation using calyculin A. This technique revealed that TIG-1 and Hela cells bore clearly different sub-membrane mechanical structures. TIG-1 cells had aligned stiff filamentous structures, whereas Hela cells had crooked and relatively soft filaments. The surface stiffness of TIG-1 cells increased slightly by actomyosin formation due to stiffness increase of the aligned filamentous structures. On the other hand, the surface stiffness of Hela cells increased by actomyosin formation due to upregulation of the apical actin filaments. Therefore, the structural and regulatory differences of the apical actin filaments could be demonstrated by atomic force microscopy elasticity mapping analysis.展开更多
A new topology optimization method is formulated for lightweight design of multimaterial structures, using the independent continuous mapping (ICM) method to minimize the weight with a prescribed nodal displacement co...A new topology optimization method is formulated for lightweight design of multimaterial structures, using the independent continuous mapping (ICM) method to minimize the weight with a prescribed nodal displacement constraint. Two types of independent topological variable are used to identify the presence of elements and select the material for each phase, to realize the interpolations of the element stiffness matrix and total weight. Furthermore, an explicit expression for the optimized formulation is derived, using approximations of the displacement and weight given by first- and second-order Taylor expansions. The optimization problem is thereby transformed into a standard quadratic programming problem that can be solved using a sequential quadratic programming approach. The feasibility and effectiveness of the proposed multimaterial topology optimization method are demonstrated by determining the best load transfer path for four numerical examples. The results reveal that the topologically optimized configuration of the multimaterial structure varies with the material properties, load conditions, and constraint. Firstly, the weight of the optimized multimaterial structure is found to be lower than that composed of a single material. Secondly, under the precondition of a displacement constraint, the weight of the topologically optimized multimaterial structure decreases as the displacement constraint value is increased. Finally, the topologically optimized multimaterial structures differ depending on the elastic modulus of the materials. Besides, the established optimization formulation is more reliable and suitable for use in practical engineering applications with structural performance parameters as constraint.展开更多
Joha rice of Assam is a class of rice with aroma, good cooking qualities and excellent palatability, which are grown in different places of Assam with their adaptability to local situations. A total of 143 simple sequ...Joha rice of Assam is a class of rice with aroma, good cooking qualities and excellent palatability, which are grown in different places of Assam with their adaptability to local situations. A total of 143 simple sequence repeat markers were used in this study to reveal sufficient genetic variations among the 40 Joha and 14 non-Joha rice genotypes. Polymorphism information content of these markers were from 0.17 to 0.88, where the average of 3.7 alleles were observed. The model-based population assignment and dendrogram analysis identified three distinct groups in the 54 rice accessions, which established a clear identity of Joha accessions from the Basmati accessions, indicating high diversity and strong population structure in Joha rice. Furthermore, a total of 29 significant marker-trait associations(P < 0.05) for 10 characters were detected. The QTLs related with yield and grain quality can be used effectively in crop improvement programs and for further fine mapping and validation of specific genes to develop gene-based perfect markers in rice breeding and for mining of better alleles of these genes in Joha rice collections.展开更多
Membrane proteins are an important kind of proteins embedded in the membranes of cells and play crucial roles in living organisms, such as ion channels,transporters, receptors. Because it is difficult to determinate t...Membrane proteins are an important kind of proteins embedded in the membranes of cells and play crucial roles in living organisms, such as ion channels,transporters, receptors. Because it is difficult to determinate the membrane protein's structure by wet-lab experiments,accurate and fast amino acid sequence-based computational methods are highly desired. In this paper, we report an online prediction tool called Mem Brain, whose input is the amino acid sequence. Mem Brain consists of specialized modules for predicting transmembrane helices, residue–residue contacts and relative accessible surface area of a-helical membrane proteins. Mem Brain achieves aprediction accuracy of 97.9% of ATMH, 87.1% of AP,3.2 ± 3.0 of N-score, 3.1 ± 2.8 of C-score. Mem BrainContact obtains 62%/64.1% prediction accuracy on training and independent dataset on top L/5 contact prediction,respectively. And Mem Brain-Rasa achieves Pearson correlation coefficient of 0.733 and its mean absolute error of13.593. These prediction results provide valuable hints for revealing the structure and function of membrane proteins.Mem Brain web server is free for academic use and available at www.csbio.sjtu.edu.cn/bioinf/Mem Brain/.展开更多
Flexible,compact,lightweight and sustainable power sources are indispensable for modern wearable and personal electronics and small-unmanned aerial vehicles(UAVs).Hierarchical honeycomb has the unique merits of compac...Flexible,compact,lightweight and sustainable power sources are indispensable for modern wearable and personal electronics and small-unmanned aerial vehicles(UAVs).Hierarchical honeycomb has the unique merits of compact mesostructures,excellent energy absorption properties and considerable weight to strength ratios.Herein,a honeycomb-inspired triboelectric nanogenerator(h-TENG)is proposed for biomechanical and UAV morphing wing energy harvesting based on contact triboelectrification wavy surface of cellular honeycomb structure.The wavy surface comprises a multilayered thin film structure(combining polyethylene terephthalate,silver nanowires and fluorinated ethylene propylene)fabricated through high-temperature thermoplastic molding and wafer-level bonding process.With superior synchronization of large amounts of energy generation units with honeycomb cells,the manufactured h-TENG prototype produces the maximum instantaneous open-circuit voltage,short-circuit current and output power of 1207 V,68.5μA and 12.4 mW,respectively,corresponding to a remarkable peak power density of 0.275 mW cm^(−3)(or 2.48 mW g^(−1))under hand pressing excitations.Attributed to the excellent elastic property of self-rebounding honeycomb structure,the flexible and transparent h-TENG can be easily pressed,bent and integrated into shoes for real-time insole plantar pressure mapping.The lightweight and compact h-TENG is further installed into a morphing wing of small UAVs for efficiently converting the flapping energy of ailerons into electricity for the first time.This research demonstrates this new conceptualizing single h-TENG device’s versatility and viability for broad-range real-world application scenarios.展开更多
During mechanical alloying variables such as the type of mill,milling intensity,milling time,milling at- mosphere and ball-to-powder weight ratio(BPR)affect the morphology and constitution of the product. The effect o...During mechanical alloying variables such as the type of mill,milling intensity,milling time,milling at- mosphere and ball-to-powder weight ratio(BPR)affect the morphology and constitution of the product. The effect of milling time,milling atmosphere and BPR on the nature of the product formed in mechanical- ly alloyed pure Ti and blended elemental binary Ti-Al,and ternary Ti-AI-Nb alloy powders was described. Mechanical alloying of pure titanium results,after long milling times,in the formation of an fcc phase.In the binary alloy,a solid solution of aluminum in titanium,an amorphous phase,and a fcc phase form with increasing milling time.The fcc phase,which is probably a result of TiN formation,occurs more rapidly in air or nitrogen than in an inert atmosphere.Formation of the B2 phase in the ternary alloys depends both on alloy composition and the milling atmosphere,with 100% formation in all atmospheres in Ti-25Al-25Nb but not in Ti-24Al-11Nb,and an inert atmosphere favoring formation.The times required for the formation of the different phases decrease as the BPR increases;but their sequence is unaffected.Based on this infor- mation,“milling maps”which describe phase formation as a function of the BPR and milling time are con- structed.Contamination from the milling balls increased as the BPR was increased.展开更多
The open question raised by Reich is studied in a Banach space with uniform normal structure, whose norm is uniformly Gateaux differentiable. Under more suitable assumptions imposed on an asymptotically nonexpansive m...The open question raised by Reich is studied in a Banach space with uniform normal structure, whose norm is uniformly Gateaux differentiable. Under more suitable assumptions imposed on an asymptotically nonexpansive mapping, an affirmative answer to Reich' s open question is given. The results presented extend and improve Zhang Shisheng' s recent ones in the following aspects : (i) Zhang' s stronger condition that the sequence of iterative parameters converges to zero is removed; (ii) Zhang' s stronger assumption that the asymptotically nonexpansive mapping has a fixed point is removed; (iii) Zhang' s stronger condition that the sequence generated by the Banach Contraction Principle is strongly convergent is also removed. Moreover, these also extend and improve the corresponding ones obtained previously by several authors including Reich, Shioji, Takahashi,Ueda and Wittmann.展开更多
The ionization rate of Rydberg lithium atoms in a static electric field is examined within semiclassical theory which involves scattering effects off the core. By semiclassical analysis, this ionization process can be...The ionization rate of Rydberg lithium atoms in a static electric field is examined within semiclassical theory which involves scattering effects off the core. By semiclassical analysis, this ionization process can be considered as the promoted valence electrons escaping through the Stark saddle point into the ionization channels. The resulting escape spectrum of the ejected electrons demonstrates a remarkable irregular electron pulse train in time-dependence and a complicated nesting structure with respect to the initial launching angles. Based on the Poincaré} map and homoclinic tangle approach, the chaotic behaviour along with its corresponding fractal self-similar structure of the ionization spectra are analysed in detail. Our work is significant for understanding the quantum-classical correspondence.展开更多
The independent continuous mapping(ICM) method is integrated into element free Galerkin method and a new implementation of topology optimization for continuum structure is presented.To facilitate the enforcement of ...The independent continuous mapping(ICM) method is integrated into element free Galerkin method and a new implementation of topology optimization for continuum structure is presented.To facilitate the enforcement of the essential boundary condition and derivative of various sensitivities,a singular weight function in element free Galerkin method is introduced.Material point variable is defined to illustrate the condition of material point and its vicinity instead of element or node.The topological variables field is constructed by moving least square approximation which inherits the continuity and smoothness of the weight function.Due to reciprocal relationships between the topological variables and design variables,various structural responses sensitivities are derived according to the method for calculating the partial derivatives of compound functions.Numerical examples indicate that checkerboard pattern and mesh-dependence phenomena are overcome without additional restriction methods.展开更多
In lhis paper we draw some coincidence and common fixed point theorems fornonlinear hybrid contraction mappings on probabilistic metric spaces with a convexstructure.
基金supported by the Natural ScienceFoundation of Jiangsu Province of China (Grant No.SBK2010294)an Open Project Program of Jiangsu Key Laboratory of the Ministry of Education for Plant Functional Genomics (Grant No. K10001)
文摘Leaf-color mutations are a widely-observed class of mutations, playing an important role in the study of chlorophyll biosynthesis and plant chloroplast structure, function, genetics and development. A naturally-occurring leaf-color rice mutant, Baihuaidao 7, was analyzed. Mutant plants typically exhibited a green-white-green leaf-color progression, but this phenotype was only expressed in the presence of a stress signal induced by mechanical scarification such as transplantation. Prior to the appearance of white ~eaves, mutant plant growth, leaf color, chlorophyll content, and chloroplast ultrastructure appeared to be identical to those of the wild type. After the changeover to white leaf color, an examination of the mutated leaves revealed a decrease in total chlorophyll, chlorophyll a, chlorophyll b, and carotenoid content, a reduction in the number of chloroplast grana lamella and grana, and a gradual degradation of the thylakoid lamellas. At maturity, the mutant plant was etiolated and dwarfed compared with wild-type plants. Genetic analysis indicated that the leaf mutant character is controlled by a recessive nuclear gene. Genetic mapping of the mutant gene was performed using an F2 population derived from a Baihuaidao 7 ~ Jiangxi 1587 cross. The mutant gene was mapped to rice chromosome 11, positioned between InDel markers L59.2-7 and L64.8-11, which are separated by approximately 740.5 kb. The mutant gene is believed to be a new leaf-color mutant gene in rice, and is tentatively designated as gwgl.
基金supported by the National Natural Science Foundation of China,No.81471308(to JL)the Stem Cell Clinical Research Project in China,No.CMR-20161129-1003(to JL)the Innovation Technology Funding of Dalian in China,No.2018J11CY025(to JL)
文摘Neural stem cells,which are capable of multi-potential differentiation and self-renewal,have recently been shown to have clinical potential for repairing central nervous system tissue damage.However,the theme trends and knowledge structures for human neural stem cells have not yet been studied bibliometrically.In this study,we retrieved 2742 articles from the PubMed database from 2013 to 2018 using "Neural Stem Cells" as the retrieval word.Co-word analysis was conducted to statistically quantify the characteristics and popular themes of human neural stem cell-related studies.Bibliographic data matrices were generated with the Bibliographic Item Co-Occurrence Matrix Builder.We identified 78 high-frequency Medical Subject Heading(MeSH)terms.A visual matrix was built with the repeated bisection method in gCLUTO software.A social network analysis network was generated with Ucinet 6.0 software and GraphPad Prism 5 software.The analyses demonstrated that in the 6-year period,hot topics were clustered into five categories.As suggested by the constructed strategic diagram,studies related to cytology and physiology were well-developed,whereas those related to neural stem cell applications,tissue engineering,metabolism and cell signaling,and neural stem cell pathology and virology remained immature.Neural stem cell therapy for stroke and Parkinson’s disease,the genetics of microRNAs and brain neoplasms,as well as neuroprotective agents,Zika virus,Notch receptor,neural crest and embryonic stem cells were identified as emerging hot spots.These undeveloped themes and popular topics are potential points of focus for new studies on human neural stem cells.
基金This project is supported by National Natural Science Foundation ofChina(No.l9832020) and National Outstanding Youth Science Foundation ofChina(No.10125208).
文摘A physical value mapping (PVM) algorithm based on finite element mesh from the stamped part in stamping process to the product is presented, In order to improve the efficiency of the PVM algorithm, a search way from the mesh of the product to the mesh of the stamped part will be adopted. At the same time, the search process is divided into two steps: entire search (ES) and local search (LS), which improve the searching efficiency. The searching area is enlarged to avoid missing projection elements in ES process. An arc-length method is introduced in LS process. The validity is confirmed by the results of the complex industry-forming product.
基金Project(2014CB239205)supported by the National Basic Research Program of ChinaProject(20011ZX05030-005-003)supported by the National Science and Technology Major Project of China
文摘Faults and fractures of multiple scales are frequently induced and generated in compressional structural system. Comprehensive identification of these potential faults and fractures that cannot be distinguished directly from seismic profile of the complex structures is still an unanswered problem. Based on the compressional structural geometry and kinematics theories as well as the structural interpretation from seismic data, a set of techniques is established for the identification of potential faults and fractures in compressional structures. Firstly, three-dimensional(3D) patterns and characteristics of the faults directly interpreted from seismic profile were illustrated by 3D structural model. Then, the unfolding index maps, the principal structural curvature maps, and tectonic stress field maps were obtained from structural restoration. Moreover, potential faults and fractures in compressional structures were quantitatively identified relying on comprehensive analysis of these three maps. Successful identification of the potential faults and fractures in Mishrif limestone formation and in Asmari dolomite formation of Buzurgan anticline in Iraq demonstrates the applicability and reliability of these techniques.
基金National Key Research and Development Program(No.2018YFB1305001)Major Consulting and Research Project of Chinese Academy of Engineering(No.2018-ZD-02-07)。
文摘Taking autonomous driving and driverless as the research object,we discuss and define intelligent high-precision map.Intelligent high-precision map is considered as a key link of future travel,a carrier of real-time perception of traffic resources in the entire space-time range,and the criterion for the operation and control of the whole process of the vehicle.As a new form of map,it has distinctive features in terms of cartography theory and application requirements compared with traditional navigation electronic maps.Thus,it is necessary to analyze and discuss its key features and problems to promote the development of research and application of intelligent high-precision map.Accordingly,we propose an information transmission model based on the cartography theory and combine the wheeled robot’s control flow in practical application.Next,we put forward the data logic structure of intelligent high-precision map,and analyze its application in autonomous driving.Then,we summarize the computing mode of“Crowdsourcing+Edge-Cloud Collaborative Computing”,and carry out key technical analysis on how to improve the quality of crowdsourced data.We also analyze the effective application scenarios of intelligent high-precision map in the future.Finally,we present some thoughts and suggestions for the future development of this field.
基金supported by the National Natural Science Foundation of China(NSFC,31970564,32000397,32171982)the Fundamental Research Funds for the Central Universities(2662023PY004)。
文摘"Synthetic"allopolyploids recreated by interspecific hybridization play an important role in providing novel genomic variation for crop improvement.Such synthetic allopolyploids often undergo rapid genomic structural variation(SV).However,how such SV arises,is inherited and fixed,and how it affects important traits,has rarely been comprehensively and quantitively studied in advanced generation synthetic lines.A better understanding of these processes will aid breeders in knowing how to best utilize synthetic allopolyploids in breeding programs.Here,we analyzed three genetic mapping populations(735 DH lines)derived from crosses between advanced synthetic and conventional Brassica napus(rapeseed)lines,using whole-genome sequencing to determine genome composition.We observed high tolerance of large structural variants,particularly toward the telomeres,and preferential selection for balanced homoeologous exchanges(duplication/deletion events between the A and C genomes resulting in retention of gene/chromosome dosage between homoeologous chromosome pairs),including stable events involving whole chromosomes("pseudoeuploidy").Given the experimental design(all three populations shared a common parent),we were able to observe that parental SV was regularly inherited,showed genetic hitchhiking effects on segregation,and was one of the major factors inducing adjacent novel and larger SV.Surprisingly,novel SV occurred at low frequencies with no significant impacts on observed fertility and yield-related traits in the advanced generation synthetic lines.However,incorporating genome-wide SV in linkage mapping explained significantly more genetic variance for traits.Our results provide a framework for detecting and understanding the occurrence and inheritance of genomic SV in breeding programs,and support the use of synthetic parents as an important source of novel trait variation.
基金National Natural Science Foundation of China(Grant Nos.51201015 and U1532262).
文摘Five-fold twinned nanostructures are intrinsically strained or relaxed by extended defects to satisfy the space-filling requirement.Although both of metallic and semiconductor five-fold twinned nanostructures show inhomogeneity in their cross-sectional strain distribution,the evident strain concentration at twin boundaries in the semiconductor systems has been found in contrast to the metallic systems.Naturally,a problem is raised how the chemical bonding characteristics of various five-fold twinned nanosystems affects their strain-relieving defect structures.Here using three-dimensional(3D)electron diffraction mapping methodology,the intrinsic strain and the strain-relieving defects in a pentagonal Ag nanowire and a star-shaped boron carbide nanowire,both of them have basically equal radial twin-plane width about 30 nm,are nondestructively characterized.The non-uniform strain and defect distribution between the five single crystalline segments are found in both of the five-fold twinned nanowires.Diffraction intensity fine structure analysis for the boron carbide five-fold twinned nanowire indicates the presence of high-density of planar defects which are responsible for the accommodation of the intrinsic angular excess.However,for the Ag five-fold twinned nanowire,the star-disclination strain field is still present,although is partially relieved by the formation of localized stacking fault layers accompanied by partial dislocations.Energetic analysis suggests that the variety in the strain-relaxation ways for the two types of five-fold twinned nanowires could be ascribed to the large difference in shear modulus between the soft noble metal Ag and the superhard covalent compound boron carbide.
基金National Hi-tech Research and Development Program of China(863 Program,Grant No.2015BAF04B00)China Aerospace Science and Technology Corporation Program of China(CASIC Program,Grant No.461717)
文摘In order to solve the problem of substantial computational resources of lattice structure during optimization, a local relative density mapping(LRDM) method is proposed. The proposed method uses solid isotropic microstructures with penalization to optimize a model at the macroscopic scale. The local relative density information is obtained from the topology optimization result. The contour lines of an optimized model are extracted using a density contour approach, and the triangular mesh is generated using a mesh generator. A local mapping relationship between the elements’ relative density and the struts’ relative cross?sectional area is established to automatically determine the diameter of each individual strut in the lattice structures. The proposed LRDM method can be applied to local finite element meshes and local density elements, but it is also suitable for global ones. In addition, some cases are con?sidered in order to test the e ectiveness of the LRDM method. The results show that the solution time of the LRDM is lower than the RDM method by approximately 50%. The proposed method provides instructions for the design of more complex lattice structures.
文摘The first important problem in the star forming process is the formation of proto star core in star forming regions of molecular cloud. The multi core structure in star forming regions is related to the forming of proto star core. The molecular radiation of C 18 O( J = 1-0) in Cepheus C has been observed. The C 18 O( J = 1-0) observations form the basis for an interesting study on the cloud cores and star formation activity in the cores of the Cepheus C. In order to study the multi core structure of C 18 O( J = 1-0) in the Cepheus C the channel maps and the position velocity diagrams of C 18 O( J = 1-0) will be shown. From the maps it is found that the contour level and distribution size of the three cores in Cepheus C are related to the channel velocity very much. The channel velocity of C 18 O( J = 1-0) molecules in core b, which distributed in all the channels velocity, is different with one in core a and core c very much. The C 18 O( J = 1-0) molecules in core a and core c of the Cepheus C mostly distributed in the blue shifted channel velocity relating to peak velocity, and only in -10.0 ~ -9.5 km/s, which is the red shifted channel velocity relating to peak velocity. And the contour level of C 18 O( J = 1-0) in -10.0 ~ -9.5 km/s is small and the distrbution size in the channel map is small. According to the position velocity diagrams the asymmetry of the distribution both blue shifted and red shifted components should reflect the asymmetry of the profile. From the diagrams it also is found that the contour level and the distribution size of the three cores are different from each other. Both results from the maps and diagrams are coincident with each other.
文摘The cell mechanical features are largely regulated by actin cytokeleton. By analyzing the mechanical features, it is possible to evaluate the characteristics of the complicated actin cytoskeleton in diverse cell types. In this study, we examined the sub-membrane mechanical structures of normal fibroblasts TIG-1 cells, and cervical cancer Hela cells using local elasticity mapping method of atomic force microscope. Especially we aimed at clarifying the regulatory mechanisms of sub-membrane actin structures in these cells by activation of actomyosin formation using calyculin A. This technique revealed that TIG-1 and Hela cells bore clearly different sub-membrane mechanical structures. TIG-1 cells had aligned stiff filamentous structures, whereas Hela cells had crooked and relatively soft filaments. The surface stiffness of TIG-1 cells increased slightly by actomyosin formation due to stiffness increase of the aligned filamentous structures. On the other hand, the surface stiffness of Hela cells increased by actomyosin formation due to upregulation of the apical actin filaments. Therefore, the structural and regulatory differences of the apical actin filaments could be demonstrated by atomic force microscopy elasticity mapping analysis.
基金the National Natural Science Foundation of China (Grants 11072009 and 11872080)Beijing Education Committee Development Project (Grant SQKM201610005001).
文摘A new topology optimization method is formulated for lightweight design of multimaterial structures, using the independent continuous mapping (ICM) method to minimize the weight with a prescribed nodal displacement constraint. Two types of independent topological variable are used to identify the presence of elements and select the material for each phase, to realize the interpolations of the element stiffness matrix and total weight. Furthermore, an explicit expression for the optimized formulation is derived, using approximations of the displacement and weight given by first- and second-order Taylor expansions. The optimization problem is thereby transformed into a standard quadratic programming problem that can be solved using a sequential quadratic programming approach. The feasibility and effectiveness of the proposed multimaterial topology optimization method are demonstrated by determining the best load transfer path for four numerical examples. The results reveal that the topologically optimized configuration of the multimaterial structure varies with the material properties, load conditions, and constraint. Firstly, the weight of the optimized multimaterial structure is found to be lower than that composed of a single material. Secondly, under the precondition of a displacement constraint, the weight of the topologically optimized multimaterial structure decreases as the displacement constraint value is increased. Finally, the topologically optimized multimaterial structures differ depending on the elastic modulus of the materials. Besides, the established optimization formulation is more reliable and suitable for use in practical engineering applications with structural performance parameters as constraint.
基金Department of Biotechnology, Government of India for the research grant (Grant No.BT/PR-9309/AGR/02/408/2007)
文摘Joha rice of Assam is a class of rice with aroma, good cooking qualities and excellent palatability, which are grown in different places of Assam with their adaptability to local situations. A total of 143 simple sequence repeat markers were used in this study to reveal sufficient genetic variations among the 40 Joha and 14 non-Joha rice genotypes. Polymorphism information content of these markers were from 0.17 to 0.88, where the average of 3.7 alleles were observed. The model-based population assignment and dendrogram analysis identified three distinct groups in the 54 rice accessions, which established a clear identity of Joha accessions from the Basmati accessions, indicating high diversity and strong population structure in Joha rice. Furthermore, a total of 29 significant marker-trait associations(P < 0.05) for 10 characters were detected. The QTLs related with yield and grain quality can be used effectively in crop improvement programs and for further fine mapping and validation of specific genes to develop gene-based perfect markers in rice breeding and for mining of better alleles of these genes in Joha rice collections.
基金supported by the National Natural Science Foundation of China(Nos.61671288,91530321,61603161)Science and Technology Commission of Shanghai Municipality(Nos.16JC1404300,17JC1403500,16ZR1448700)
文摘Membrane proteins are an important kind of proteins embedded in the membranes of cells and play crucial roles in living organisms, such as ion channels,transporters, receptors. Because it is difficult to determinate the membrane protein's structure by wet-lab experiments,accurate and fast amino acid sequence-based computational methods are highly desired. In this paper, we report an online prediction tool called Mem Brain, whose input is the amino acid sequence. Mem Brain consists of specialized modules for predicting transmembrane helices, residue–residue contacts and relative accessible surface area of a-helical membrane proteins. Mem Brain achieves aprediction accuracy of 97.9% of ATMH, 87.1% of AP,3.2 ± 3.0 of N-score, 3.1 ± 2.8 of C-score. Mem BrainContact obtains 62%/64.1% prediction accuracy on training and independent dataset on top L/5 contact prediction,respectively. And Mem Brain-Rasa achieves Pearson correlation coefficient of 0.733 and its mean absolute error of13.593. These prediction results provide valuable hints for revealing the structure and function of membrane proteins.Mem Brain web server is free for academic use and available at www.csbio.sjtu.edu.cn/bioinf/Mem Brain/.
基金This research is supported by the National Natural Science Foundation of China Grant(Nos.51705429&61801525)the Fundamental Research Funds for the Central Universities,Guangdong Natural Science Funds Grant(2018A030313400)+1 种基金Space Science and Technology Foundation,111 Project No.B13044UK Engineering and Physical Sciences Research Council(EPSRC)for support under grant EP/P018998/1,Newton Mobility Grant(IE161019)through Royal Society.
文摘Flexible,compact,lightweight and sustainable power sources are indispensable for modern wearable and personal electronics and small-unmanned aerial vehicles(UAVs).Hierarchical honeycomb has the unique merits of compact mesostructures,excellent energy absorption properties and considerable weight to strength ratios.Herein,a honeycomb-inspired triboelectric nanogenerator(h-TENG)is proposed for biomechanical and UAV morphing wing energy harvesting based on contact triboelectrification wavy surface of cellular honeycomb structure.The wavy surface comprises a multilayered thin film structure(combining polyethylene terephthalate,silver nanowires and fluorinated ethylene propylene)fabricated through high-temperature thermoplastic molding and wafer-level bonding process.With superior synchronization of large amounts of energy generation units with honeycomb cells,the manufactured h-TENG prototype produces the maximum instantaneous open-circuit voltage,short-circuit current and output power of 1207 V,68.5μA and 12.4 mW,respectively,corresponding to a remarkable peak power density of 0.275 mW cm^(−3)(or 2.48 mW g^(−1))under hand pressing excitations.Attributed to the excellent elastic property of self-rebounding honeycomb structure,the flexible and transparent h-TENG can be easily pressed,bent and integrated into shoes for real-time insole plantar pressure mapping.The lightweight and compact h-TENG is further installed into a morphing wing of small UAVs for efficiently converting the flapping energy of ailerons into electricity for the first time.This research demonstrates this new conceptualizing single h-TENG device’s versatility and viability for broad-range real-world application scenarios.
文摘During mechanical alloying variables such as the type of mill,milling intensity,milling time,milling at- mosphere and ball-to-powder weight ratio(BPR)affect the morphology and constitution of the product. The effect of milling time,milling atmosphere and BPR on the nature of the product formed in mechanical- ly alloyed pure Ti and blended elemental binary Ti-Al,and ternary Ti-AI-Nb alloy powders was described. Mechanical alloying of pure titanium results,after long milling times,in the formation of an fcc phase.In the binary alloy,a solid solution of aluminum in titanium,an amorphous phase,and a fcc phase form with increasing milling time.The fcc phase,which is probably a result of TiN formation,occurs more rapidly in air or nitrogen than in an inert atmosphere.Formation of the B2 phase in the ternary alloys depends both on alloy composition and the milling atmosphere,with 100% formation in all atmospheres in Ti-25Al-25Nb but not in Ti-24Al-11Nb,and an inert atmosphere favoring formation.The times required for the formation of the different phases decrease as the BPR increases;but their sequence is unaffected.Based on this infor- mation,“milling maps”which describe phase formation as a function of the BPR and milling time are con- structed.Contamination from the milling balls increased as the BPR was increased.
文摘The open question raised by Reich is studied in a Banach space with uniform normal structure, whose norm is uniformly Gateaux differentiable. Under more suitable assumptions imposed on an asymptotically nonexpansive mapping, an affirmative answer to Reich' s open question is given. The results presented extend and improve Zhang Shisheng' s recent ones in the following aspects : (i) Zhang' s stronger condition that the sequence of iterative parameters converges to zero is removed; (ii) Zhang' s stronger assumption that the asymptotically nonexpansive mapping has a fixed point is removed; (iii) Zhang' s stronger condition that the sequence generated by the Banach Contraction Principle is strongly convergent is also removed. Moreover, these also extend and improve the corresponding ones obtained previously by several authors including Reich, Shioji, Takahashi,Ueda and Wittmann.
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10774093 and 10374061)
文摘The ionization rate of Rydberg lithium atoms in a static electric field is examined within semiclassical theory which involves scattering effects off the core. By semiclassical analysis, this ionization process can be considered as the promoted valence electrons escaping through the Stark saddle point into the ionization channels. The resulting escape spectrum of the ejected electrons demonstrates a remarkable irregular electron pulse train in time-dependence and a complicated nesting structure with respect to the initial launching angles. Based on the Poincaré} map and homoclinic tangle approach, the chaotic behaviour along with its corresponding fractal self-similar structure of the ionization spectra are analysed in detail. Our work is significant for understanding the quantum-classical correspondence.
基金Sponsored by the Ministerial Level Advanced Research Foundation (010896367)
文摘The independent continuous mapping(ICM) method is integrated into element free Galerkin method and a new implementation of topology optimization for continuum structure is presented.To facilitate the enforcement of the essential boundary condition and derivative of various sensitivities,a singular weight function in element free Galerkin method is introduced.Material point variable is defined to illustrate the condition of material point and its vicinity instead of element or node.The topological variables field is constructed by moving least square approximation which inherits the continuity and smoothness of the weight function.Due to reciprocal relationships between the topological variables and design variables,various structural responses sensitivities are derived according to the method for calculating the partial derivatives of compound functions.Numerical examples indicate that checkerboard pattern and mesh-dependence phenomena are overcome without additional restriction methods.
文摘In lhis paper we draw some coincidence and common fixed point theorems fornonlinear hybrid contraction mappings on probabilistic metric spaces with a convexstructure.