A new type of grain-interior planar defect in a ceramic phase in TiC doped cemented tungsten carbides was discovered.It is unique in that the monolayers of metal atoms exist stably in ceramic grains.The planar defects...A new type of grain-interior planar defect in a ceramic phase in TiC doped cemented tungsten carbides was discovered.It is unique in that the monolayers of metal atoms exist stably in ceramic grains.The planar defects were induced by the ordered heteroatoms distributing on certain crystal planes of the matrix,which are distinct from the known planar defects such as phase-,grain-,and twin-boundaries,stacking faults,and complexions.Detailed characterization on the atomic scale was performed for the composition,structure,and crystallography of the planar defects,and their energy state and stability were evaluated by modeling.It was found that the Ti monolayer assists nucleation of the new WC crystal along the normal direction to its basal plane.Due to the disturbance of the heteroatom layer,the deposition of W and C atoms deviates from the regular sites occupied in the perfect crystal lattice,resulting in variations of the W–C arrangement in the grain structure.Experiments confirmed that tailoring the distribution density of the planar defects could give the best comprehensive mechanical performance with simultaneously outstanding strength and fracture toughness in the materials containing the grain-interior planar defects.This study provides a new strategy to greatly enhance the mechanical properties of materials by introducing and tailoring planar defects in the grain interiors.展开更多
The evolution and transition of planar wave trains propagating through defects(obstacles) in an excitable medium are studied. When the frequency of the planar wave trains is increased, three different dynamical regime...The evolution and transition of planar wave trains propagating through defects(obstacles) in an excitable medium are studied. When the frequency of the planar wave trains is increased, three different dynamical regimes,namely fusion, "V" waves, and spiral waves, are observed in turn and the underlying mechanism is discussed. The dynamics is concerned with the shapes of the defects. Circle, triangle, and rectangle defects with different sizes are considered. The increase of pacing frequency broadens the fan-shaped broken region in the behind of a rectangle defect.The increase of width of a triangle defect leads to breakup of wave trains easier while the change of height shows opposite effect, which is presented in a phase diagram. Dynamical comparison on defects with different shapes indicates that the decrease of the defect width along the propagation of wave trains makes the fan-shaped region and the minimal frequency for breakup of spiral both increased.展开更多
Background: VANGL2 plays a variety of roles in various cellular processes, including tissue morphogenesis, asymmetric cell division, and nervous system development. There is currently a lack of systematic organization...Background: VANGL2 plays a variety of roles in various cellular processes, including tissue morphogenesis, asymmetric cell division, and nervous system development. There is currently a lack of systematic organization in the development and disease of the nervous system. Purpose: To explore the role of VANGL2 in the development of the nervous system and related diseases. Methods: Literature review and analysis of the role of VANGL2 in the development and disease of the nervous system. Results: VANGL2 defects lead to the development of the nervous system through the misconfiguration of various cells, which affects the development of the cochlea, the conduction of neural signals, and the development of nervous system-related diseases such as Alzheimer’s disease, GBM, Bohling-Opitz syndrome, and hydrocephalus. Conclusions: The VANGL2 gene is essential for nervous system development and its deficiency is linked to severe congenital conditions and various disorders, highlighting the need for more research on treatments for related gene defects.展开更多
针对铝合金厚板焊缝中易于出现的几种典型的面状缺陷,研究了其超声衍射时间差法(TOFD-time of flight diffraction)的检测特征,对获得的A扫描信号和B、D扫描图像的特征进行了分析和解释,并对B、D扫描图像进行了线性化处理。结果表明,结...针对铝合金厚板焊缝中易于出现的几种典型的面状缺陷,研究了其超声衍射时间差法(TOFD-time of flight diffraction)的检测特征,对获得的A扫描信号和B、D扫描图像的特征进行了分析和解释,并对B、D扫描图像进行了线性化处理。结果表明,结合A扫描信号和B、D扫描图像的特征,能够有效地对面状缺陷进行识别、定位和定量。线性化处理技术有效地提高了图像的时间分辨力,使面状缺陷的信号和图像的特征更明显,进而使定位定量更为精确。展开更多
基金supported by the National Natural Science Foundation of China(92163107,52171061,52101003,52271085,and 52101032).
文摘A new type of grain-interior planar defect in a ceramic phase in TiC doped cemented tungsten carbides was discovered.It is unique in that the monolayers of metal atoms exist stably in ceramic grains.The planar defects were induced by the ordered heteroatoms distributing on certain crystal planes of the matrix,which are distinct from the known planar defects such as phase-,grain-,and twin-boundaries,stacking faults,and complexions.Detailed characterization on the atomic scale was performed for the composition,structure,and crystallography of the planar defects,and their energy state and stability were evaluated by modeling.It was found that the Ti monolayer assists nucleation of the new WC crystal along the normal direction to its basal plane.Due to the disturbance of the heteroatom layer,the deposition of W and C atoms deviates from the regular sites occupied in the perfect crystal lattice,resulting in variations of the W–C arrangement in the grain structure.Experiments confirmed that tailoring the distribution density of the planar defects could give the best comprehensive mechanical performance with simultaneously outstanding strength and fracture toughness in the materials containing the grain-interior planar defects.This study provides a new strategy to greatly enhance the mechanical properties of materials by introducing and tailoring planar defects in the grain interiors.
基金Supported by the Natural Science Foundation of Zhejiang Province under Grant Nos.LQ14A050003 and LR17A050001Zhejiang Province Commonweal Projects under Grant No.GK180906288001China Scholarship Council under Grant No.201708330401
文摘The evolution and transition of planar wave trains propagating through defects(obstacles) in an excitable medium are studied. When the frequency of the planar wave trains is increased, three different dynamical regimes,namely fusion, "V" waves, and spiral waves, are observed in turn and the underlying mechanism is discussed. The dynamics is concerned with the shapes of the defects. Circle, triangle, and rectangle defects with different sizes are considered. The increase of pacing frequency broadens the fan-shaped broken region in the behind of a rectangle defect.The increase of width of a triangle defect leads to breakup of wave trains easier while the change of height shows opposite effect, which is presented in a phase diagram. Dynamical comparison on defects with different shapes indicates that the decrease of the defect width along the propagation of wave trains makes the fan-shaped region and the minimal frequency for breakup of spiral both increased.
文摘Background: VANGL2 plays a variety of roles in various cellular processes, including tissue morphogenesis, asymmetric cell division, and nervous system development. There is currently a lack of systematic organization in the development and disease of the nervous system. Purpose: To explore the role of VANGL2 in the development of the nervous system and related diseases. Methods: Literature review and analysis of the role of VANGL2 in the development and disease of the nervous system. Results: VANGL2 defects lead to the development of the nervous system through the misconfiguration of various cells, which affects the development of the cochlea, the conduction of neural signals, and the development of nervous system-related diseases such as Alzheimer’s disease, GBM, Bohling-Opitz syndrome, and hydrocephalus. Conclusions: The VANGL2 gene is essential for nervous system development and its deficiency is linked to severe congenital conditions and various disorders, highlighting the need for more research on treatments for related gene defects.
文摘针对铝合金厚板焊缝中易于出现的几种典型的面状缺陷,研究了其超声衍射时间差法(TOFD-time of flight diffraction)的检测特征,对获得的A扫描信号和B、D扫描图像的特征进行了分析和解释,并对B、D扫描图像进行了线性化处理。结果表明,结合A扫描信号和B、D扫描图像的特征,能够有效地对面状缺陷进行识别、定位和定量。线性化处理技术有效地提高了图像的时间分辨力,使面状缺陷的信号和图像的特征更明显,进而使定位定量更为精确。
