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Lattice structures are crucial for weight reduction, and laser powder bed fusion (LPBF) is an efficient fabrication method. However, there's a notable research gap in understanding the residual deformation of LPBF-fabricated lattice structures. This study investigates the residual deformation of three basic lattice structures, body centre cell (BCC), face centre cell (FCC), and diamond cell (DC), fabricated via LPBF to reveal their deformation mechanisms. Analysis covers horizontal direction, building direction, and total deformations, unveiling complex structural responses. Lower relative densities exhibit a prevalent structural deformation mode (SDM) causing significant deformations, while higher densities shift to an intrinsic deformation mode (IDM) dominated by contraction during fabrication. The FCC structure shows optimal stability with minimal residual deformation across most densities. This study offers insightful findings and a detailed mechanistic analysis of residual deformation in LPBF-fabricated lattice structures, applicable across various configurations, ensuring design process uniformity and reliability.

Selective laser melting (SLM) produces a large amount of residual stress which limits its applicability. Despite the increasing number of studies to understand the relationship between the process parameters and the residual stress, the underlying complex mechanisms are yet to be understood. In this work, a 3D finite element model (FEM) is established to investigate the relationship between the process parameters and the residual stress during SLM. When the process parameters are in different ranges, the residual stress behavior is different. The complex relationship between the residual stress and the process parameters could be the reason for the contradictory parametric effects reported in the literature. The magnitude of the parametric effect on the residual stress is obtained. The influence of the scanning speed is stronger than that of the laser power, which is in turn stronger than that of the hatch spacing. These results can bring insights into the understanding of the residual stress during SLM.

The selective installation of quaternary carbon substituents on arenes is a highly challenging synthetic goal. Here, the authors report a chromium-catalyzed para-selective functionalization of benzamides with tertiary organometallic reagents under mild conditions.

Selective para-functionalization of substituted arenes is a formidable challenge in homogeneous catalysis. Here, the authors achieved the para-selective C-H difluoromethylation of anilides, indolines and tetrahydroquinolines with a ruthenium catalyst in good yields and apply it to the synthesis of bioactive compounds.

Using first-principles calculations, we computationally designed a new two-dimensional (2D) inorganic material, Be3N2 monolayer with a flat hexagonal structure similar to graphene. Good stability of the Be3N2 monolayer is demonstrated by its moderate cohesive energy, the absence of imaginary modes in its phonon spectrum, and the high melting point predicted by molecular dynamics (MD) simulations. The Be3N2 monolayer is a direct band gap semiconductor with a band gap of 3.831 eV that can be effectively tuned by employing an external strain. The wide band gap and outstanding strain-engineered properties make Be3N2 monolayer a highly versatile and promising 2D material for innovative applications in microelectromechanical and nanoelectronic devices. Additionally, the one-dimensional Be3N2 nanoribbons which divided by Be3N2monolayer, are computed to have quite rich characteristics such as direct band gaps with various values, depending on the direction of the division and the width of nanoribbons.

The electronic properties and optical properties of single and double Au-doped phosphorene have been comparatively investigated using the first-principles plane-wave pseudopotential method based on density functional theory. The decrease from direct band gap 0.78 eV to indirect band gap 0.22 and 0.11 eV are observed in the single and double Au-doped phosphorene, respectively. The red shifts of absorbing edge occur in both doped systems, which consequently enhance the absorbing of infrared light in phosphorene. Band gap engineering can, therefore, be used to directly tune the optical absorption of phosphorene system by substitutional Au doping. [ABSTRACT FROM AUTHOR]

Palladium-catalyzeddirect ortho-silylation ofoxalyl amide-protected phenylmethanamine and phenethylamine with commerciallyavailable disilanes is reported. Germanylation products were alsoproduced under the same reaction conditions. This protocol toleratedoxalyl amide-protected aliphatic amines, which gave γ-C–Hsilylation products. [ABSTRACT FROM AUTHOR]

A novel and efficient synthetic method for o-fluorobenzylamines via palladium catalyst using an easily accessible oxalyl amide as directing group has been developed. The cheap N-fluorobenzenesulfonimide could be used as an effective [F+] source and f-amyl-OH as the solvent with R Pd(OAc)2 as catalyst Selective mono- or difiuorination of oxalyl amide-protected benzylamine derivatives were achieved by modifying the reaction conditions, which presented an efficient method for the preparation of orfho-fluorinated benzylamines. [ABSTRACT FROM AUTHOR]

It is reported a weakly coordination-assisted alkynylation of aryl and heteroaryl carboxylic acids with iridium catalysis. The reaction is catalyzed by [{Cp*IrCl2}2] complex without cyclization, forming ortho-alkynylated aryl and heteroaryl carboxylic acids, and features high functional group tolerance and broad substrate scope under an air atmosphere. 2-(Hetero)aryl-substituted acetic acids were amenable to the alkynylation by forming an unusual six-membered ring cycloiridiated intermediate. [ABSTRACT FROM AUTHOR]