Electronic shell study of prolate Lin(n=15–17)clusters:Magnetic superatomic molecules

The non-spherical lowest-lying Lin(n=15–17)isomers were found with high symmetric compact structures,of which the stability was not rationalized in a previous report(J.Chem.Phys.1199444(2003)).Based on the newly proposed super-valence bond model,the three prolate lithium clusters can be viewed as magnetic superatomic molecules,which are composed by sharing valence electron pairs and nuclei between two superatom units,namely,Li10 or Li11,and thus their stability can be given a good understanding.Molecular orbital and chemical bonding analysis clearly reveal that the Lin(n=15–17)clusters with prolate shapes are magnetic superatomic molecules.Our work may aid in the developments of the cluster-assembled materials or superatom-bonds.

A Lightweight Electronic Water Pump Shell Defect Detection Method Based on Improved YOLOv5s

For surface defects in electronic water pump shells,the manual detection efficiency is low,prone to misdetection and leak detection,and encounters problems,such as uncertainty.To improve the speed and accuracy of surface defect detection,a lightweight detection method based on an improved YOLOv5s method is proposed to replace the traditional manual detection methods.In this method,the MobileNetV3 module replaces the backbone network of YOLOv5s,depth-separable convolution is introduced,the parameters and calculations are reduced,and CIoU_Loss is used as the loss function of the boundary box regression to improve its detection accuracy.A dataset of electronic pump shell defects is established,and the performance of the improved method is evaluated by comparing it with that of the original method.The results show that the parameters and FLOPs are reduced by 49.83%and 61.59%,respectively,compared with the original YOLOv5s model,and the detection accuracy is improved by 1.74%,which is an indication of the superiority of the improved method.To further verify the universality of the improved method,it is compared with the results using the original method on the PASCALVOC2007 dataset,which verifies that it yields better performance.In summary,the improved lightweight method can be used for the real-time detection of electronic water pump shell defects.

Semisolid forging electronic packaging shell with silicon carbon-reinforced copper composites

To fabricate electronic packaging shell of coppermatrix composite with characteristics of high ther mal conductivity and low thermal expansion coefficient, semisolid forming technology, and powder metallurgy was combined. Conventional mechanical mixing of Cu and SiC could have insufficient wettability, and a new method of semisolid processing was introduced for billets preparation. The SiC/Cu composites were first prepared by PM, and then, semisolid reheating was performed for the successive semisolid forging. Composite billets with SiC 35 % vol ume fraction were compacted and sintered pressurelessly, microstructure analysis showed that the composites pre pared by PM had high density, and the combination between SiC particles and Cualloy was good. Semisolid reheating was the crucial factor in determining the micro structure and thixotropic property of the billet. An opti mised reheating strategy was proposed： temperature 1,025 ℃and holding time 5 min.

Coulomb Interaction between Electrons and a New Concept of Atom

It is shown that the approximation of a strong Coulomb interaction between electrons results in a new model of the atom with a spatial quantization of electrons accompanied by their quantization in energy. This model implies that electrons rotate in circular orbits centered outside the atomic nucleus and only orbit axes pass through it. The Coulomb interaction between electrons leads to a spherically symmetric distribution of their orbits on the surfaces of equipotential spheres of a spherically symmetric electrostatic field of the nucleus. The distribution is similar to “inscribing” electron orbits into faces of regular nucleus-centered polyhedra so each polyhedron corresponds to a certain electron state (s, p, d, f), and a certain set of polyhedra corresponds to a certain period of the Mendeleev Table. It is shown that a spherically symmetric distribution of electron orbits gives rise to the formation of electron pairs in which electron orbits with a common axis are located symmetrically with respect to the nucleus and the orbital magnetic moments of the electrons are oppositely directed. The physical meaning of the electron spin concept becomes clear. The spin turns out to be related to the orbital magnetic moment of an electron and reflects the fact that two electrons of a pair rotate in opposite directions relative to their common axis. So the spin is one of characteristics of the electron state in the atom associated with electron rotation in the orbit centered outside the nucleus. The atomic model gives an insight into the periodicity of changes in the atomic properties with increasing nuclear charge and the reasons for an electron double energy quantization associated with different states and periods. The model shows that the atomic structure and properties can be explained by using concepts of classical mechanics and classical electrodynamics which regard the electron as a particle.

Observation of “Outlaw” Dual Aromaticity in Unexpectedly Stable Open-Shell Metal Clusters Caused by Near-Degenerate Molecular Orbital Coupling

The Hückel’s rule,Baird’s rule,and electronic shell closure model are classical and well-established concepts in chemistry,which have long been employed in rationalizing the aromaticity/antiaromaticity of organic species and stability of inorganic clusters.Thus,the observation of unique species featuring properties out of the fundamental frameworks of these rules is challenging but significant and helps in drawing a complete picture of fascinating concepts in chemistry.