Sheet metal spinning is an incremental forming process for producing axisymmetric thinwalled parts through continuous local deformation under the action of rollers.While studying the spinning process by finite element...Sheet metal spinning is an incremental forming process for producing axisymmetric thinwalled parts through continuous local deformation under the action of rollers.While studying the spinning process by finite element(FE)method,a critical bottleneck is the enormous simulation time.For beating off this challenge,a novel multi-mesh method is developed.The method can dynamically track the movement of rollers and adaptively refine the mesh.Thus,a locally refined quadrilateral computation mesh can be generated in the locally-deforming zone and reduce the unnecessary fine elements outside the locally-deforming zone.In the multi-mesh system,the fine elements and coarse elements are extracted from a storage mesh and a background mesh,respectively.Meanwhile,the hanging nodes in the locally refined mesh are removed by designing 4-refinement templates.Between computation mesh and storage mesh,a bi-cubic parametric surface fitting algorithm and accurate remapping methods are conducted to transmit geometric information and physical fields.The proposed method has been verified by two spinning processes.The results suggest that the method can save time by up to about 67%with satisfactory accuracy,especially for distributions of thickness and strain compared with the fully refined mesh.展开更多
Transposable element-based molecular markers can be utilized to investigate genetic diversity and to create genetic linkage maps.In this study,Class I and class II transposons were employed to obtain a comparative acc...Transposable element-based molecular markers can be utilized to investigate genetic diversity and to create genetic linkage maps.In this study,Class I and class II transposons were employed to obtain a comparative account of genetic diversity between wild and cultivated barley genotypes.Three types of PCR-based techniques were used:IMP(Inter MITE Polymorphism),IRAP(Inter-Retrotransposon Amplified Polymorphism)and REMAP(Retrotransposon-Microsatellite Amplified Polymorphism).Specific primer pairs for IMP,IRAP,and REMAP detected a total of 200 bands with an average of 20 bands per marker.The mean polymorphic information content(PIC)and discrimination power(D)values in all 47 genotypes from these three types of transposon-based polymorphisms were 0.910 and0.935,respectively.Unweighted Pair Group Method with Arithmetic mean(UPGMA)-based cluster analysis classified all 47 genotypes,both wild and cultivated,into separate groups consistent with their geographical origins.Sequencing followed by chromosome location of polymorphic bands enables precise gene introgression from wild gene pool to cultivated barley.The highly polymorphic nature of these marker systems makes them suitable for use in varietal identification and MAS-based breeding programs in barley and other cereals.展开更多
Acute central nervous system injuries are among the most common causes of disability worldwide,with widespread social and economic implications.Motor tract injury accounts for the majority of this disability;therefore...Acute central nervous system injuries are among the most common causes of disability worldwide,with widespread social and economic implications.Motor tract injury accounts for the majority of this disability;therefore,there is impetus to understand mechanisms underlying the pathophysiology of injury and subsequent reorganization of the motor tract that may lead to recovery.After acute central nervous system injury,there are changes in the microenvironment and structure of the motor tract.For example,ischemic stroke involves decreased local blood flow and tissue death from lack of oxygen and nutrients.Traumatic injury,in contrast,causes stretching and shearing injury to microstructures,including myelinated axons and their surrounding vessels.Both involve blood-brain barrier dysfunction,which is an important initial event.After acute central nervous system injury,motor tract reorganization occurs in the form of cortical remapping in the gray matter and axonal regeneration and rewiring in the white matter.Cortical remapping involves one cortical region taking on the role of another.cAMP-response-element binding protein is a key transcription factor that can enhance plasticity in the peri-infarct cortex.Axonal regeneration and rewiring depend on complex cell-cell interactions between axons,oligodendrocytes,and other cells.The RhoA/Rho-associated coiled-coil containing kinase signaling pathway plays a central role in axon growth/regeneration through interactions with myelin-derived axonal growth inhibitors and regulation of actin cytoskeletal dynamics.Oligodendrocytes and their precursors play a role in myelination,and neurons are involved through their voltage-gated calcium channels.Understanding the pathophysiology of injury and the biology of motor tract reorganization may allow the development of therapies to enhance recovery after acute central nervous system injury.These include targeted rehabilitation,novel pharmacotherapies,such as growth factors and axonal growth inhibitor blockade,and the implementation of neurotechnologies,such as central nervous system stimulators and robotics.The translation of these advances depends on careful alignment of preclinical studies and human clinical trials.As experimental data mount,the future is one of optimism.展开更多
基金co-supported by the supports of Guangdong Basic and Applied Basic Research Foundation(No.2019B1515120047)the National Natural Science Foundation of China(No.52130507)。
文摘Sheet metal spinning is an incremental forming process for producing axisymmetric thinwalled parts through continuous local deformation under the action of rollers.While studying the spinning process by finite element(FE)method,a critical bottleneck is the enormous simulation time.For beating off this challenge,a novel multi-mesh method is developed.The method can dynamically track the movement of rollers and adaptively refine the mesh.Thus,a locally refined quadrilateral computation mesh can be generated in the locally-deforming zone and reduce the unnecessary fine elements outside the locally-deforming zone.In the multi-mesh system,the fine elements and coarse elements are extracted from a storage mesh and a background mesh,respectively.Meanwhile,the hanging nodes in the locally refined mesh are removed by designing 4-refinement templates.Between computation mesh and storage mesh,a bi-cubic parametric surface fitting algorithm and accurate remapping methods are conducted to transmit geometric information and physical fields.The proposed method has been verified by two spinning processes.The results suggest that the method can save time by up to about 67%with satisfactory accuracy,especially for distributions of thickness and strain compared with the fully refined mesh.
基金support of the Natural Sciences and Engineering Research Council (NSERC-Discovery) of Canada (RGPIN-2015-06652)
文摘Transposable element-based molecular markers can be utilized to investigate genetic diversity and to create genetic linkage maps.In this study,Class I and class II transposons were employed to obtain a comparative account of genetic diversity between wild and cultivated barley genotypes.Three types of PCR-based techniques were used:IMP(Inter MITE Polymorphism),IRAP(Inter-Retrotransposon Amplified Polymorphism)and REMAP(Retrotransposon-Microsatellite Amplified Polymorphism).Specific primer pairs for IMP,IRAP,and REMAP detected a total of 200 bands with an average of 20 bands per marker.The mean polymorphic information content(PIC)and discrimination power(D)values in all 47 genotypes from these three types of transposon-based polymorphisms were 0.910 and0.935,respectively.Unweighted Pair Group Method with Arithmetic mean(UPGMA)-based cluster analysis classified all 47 genotypes,both wild and cultivated,into separate groups consistent with their geographical origins.Sequencing followed by chromosome location of polymorphic bands enables precise gene introgression from wild gene pool to cultivated barley.The highly polymorphic nature of these marker systems makes them suitable for use in varietal identification and MAS-based breeding programs in barley and other cereals.
基金supported in part by JSPS“KAKENHI”Grant-in-Aid for Early-Career Scientists,Grant No.18K16566(to HT)Research Abroad from the Japan Brain Foundation(to HT)+2 种基金Mochida Memorial Foundation for Medical and Pharmaceutical Research of Japan(to HT)the Rotary Foundation Global Scholarship Grants,(Grant Nos.GG1759314,GG1876795)(to HT)the National Institute of Neurological Disorders and Stroke of USA,No.R25 NS065743(to RWR).
文摘Acute central nervous system injuries are among the most common causes of disability worldwide,with widespread social and economic implications.Motor tract injury accounts for the majority of this disability;therefore,there is impetus to understand mechanisms underlying the pathophysiology of injury and subsequent reorganization of the motor tract that may lead to recovery.After acute central nervous system injury,there are changes in the microenvironment and structure of the motor tract.For example,ischemic stroke involves decreased local blood flow and tissue death from lack of oxygen and nutrients.Traumatic injury,in contrast,causes stretching and shearing injury to microstructures,including myelinated axons and their surrounding vessels.Both involve blood-brain barrier dysfunction,which is an important initial event.After acute central nervous system injury,motor tract reorganization occurs in the form of cortical remapping in the gray matter and axonal regeneration and rewiring in the white matter.Cortical remapping involves one cortical region taking on the role of another.cAMP-response-element binding protein is a key transcription factor that can enhance plasticity in the peri-infarct cortex.Axonal regeneration and rewiring depend on complex cell-cell interactions between axons,oligodendrocytes,and other cells.The RhoA/Rho-associated coiled-coil containing kinase signaling pathway plays a central role in axon growth/regeneration through interactions with myelin-derived axonal growth inhibitors and regulation of actin cytoskeletal dynamics.Oligodendrocytes and their precursors play a role in myelination,and neurons are involved through their voltage-gated calcium channels.Understanding the pathophysiology of injury and the biology of motor tract reorganization may allow the development of therapies to enhance recovery after acute central nervous system injury.These include targeted rehabilitation,novel pharmacotherapies,such as growth factors and axonal growth inhibitor blockade,and the implementation of neurotechnologies,such as central nervous system stimulators and robotics.The translation of these advances depends on careful alignment of preclinical studies and human clinical trials.As experimental data mount,the future is one of optimism.
