Effect of Edge Reconstruction on the Growth Mechanism of Black Phosphorene.

Based on our previous studies, the reconstruction of interlayer edges of black phosphorene (BP) is identified as a key factor impeding the growth of large-size BP films through the CVD method. In this study, we systematically explore the complex growth mechanisms of BP, specifically focusing on how edge reconstruction influences the growth of BP. The results reveal that BP with reconstructed edges is highly stable.

Role of Edge Reconstruction in the Synthesis of Few-Layer Black Phosphorene.

Recent advancements in preparing few-layer black phosphorene (BP) are hindered by edge reconstruction challenges. Our previous studies have revealed the factors contributing to the difficulty of growing few-layer BP. In this study, we have successfully identified three reconstructed edges in bi- and multilayer BP through a combination of the crystal structure analysis by particle swarm optimization (CALYPSO) global structure search and density functional theory (DFT).

The Atomic Drill Bit: Precision Controlled Atomic Fabrication of 2D Materials.

The ability to deterministically fabricate nanoscale architectures with atomic precision is the central goal of nanotechnology, whereby highly localized changes in the atomic structure can be exploited to control device properties at their fundamental physical limit. Here, an automated, feedback-controlled atomic fabrication method is reported and the formation of 1D-2D heterostructures in MoS is demonstrated through selective transformations along specific crystallographic orientations. The atomic-scale probe of an aberration-corrected scanning transmission electron microscope (STEM) is used, and the shape and symmetry of the scan pathway relative to the sample orientation are controlled.

Association of COVID-19 patient's condition with fasting blood glucose and body mass index: A retrospective study.

Background: The COVID-19 pandemic broke out in 2019 and rapidly spread across the globe. Most of the severe and dead cases are middle-aged and elderly patients with chronic systemic diseases.

Objective: This study aimed to assess the association between fasting blood glucose (FPG) and body mass index (BMI) levels in patients with coronavirus disease 2019 (COVID-19) under different conditions.

Self-passivated edges of ZnO nanoribbons: a global search.

The edge structure of two-dimensional (2D) materials plays a critical role in controlling their growth kinetics and morphological evolution, electronic structures and functionalities. However, until now, the accurate edge reconstruction of ZnO nanoribbons remains absent. Here, we present results of a global search of ZnO edge structures having used the CALYPSO program combined with the density functional theory (DFT) method.

Structures and Electronic and Hydrogen Storage Properties of Magnesium Scandium Hydrides.

MgH is well known as a potential hydrogen storage material. However, its high thermodynamic stability, high dissociation temperature, slow absorption, and desorption kinetics severely limit its application. Aiming at these shortcomings, we try to improve the hydrogen storage property of MgH by doping with transition metal Sc atoms.

Atomically Sharp, Closed Bilayer Phosphorene Edges by Self-Passivation.

Two-dimensional crystals' edge structures not only influence their overall properties but also dictate their formation due to edge-mediated synthesis and etching processes. Edges must be carefully examined because they often display complex, unexpected features at the atomic scale, such as reconstruction, functionalization, and uncontrolled contamination. Here, we examine atomic-scale edge structures and uncover reconstruction behavior in bilayer phosphorene.

Why Carbon Nanotubes Grow.

Despite three decades of intense research efforts, the most fundamental question "why do carbon nanotubes grow?" remains unanswered. In fact, carbon nanotubes (CNTs) should not grow since the encapsulation of a catalyst with graphitic carbon is energetically more favorable than CNT growth in every aspect. Here, we answer this question using a theoretical model based on extensive first-principles and molecular dynamics calculations.

Mechanism of 2D Materials' Seamless Coalescence on a Liquid Substrate.

The seamless coalescence of parallelly aligned 2D materials is the primary route toward the synthesis of wafer-scale single crystals (WSSCs) of 2D materials. The epitaxial growth of various 2D materials on a single-crystal substrate, which is an essential condition of the seamless coalescence approach, has been extensively explored in previous studies. Here, by using hexagonal boron nitride (hBN) growth on a liquid gold surface as an example, we demonstrate that growth of WSSCs of 2D materials the seamless coalescence of self-aligned 2D islands on a liquid substrate is possible.

[Effects of hypoxia combined with LPS on the expression of pro- inflammatory cytokines and BNIP3 in primary cultured astrocyte].

To investigate the expression of Bcl-2/E1B-19K-interacting protein 3 (BNIP3) and inflammation in astrocytes under lipopolysaccharide ( LPS ) combined with hypoxia. Primary cultured astrocytes and neurons in vitro were divided into four groups: normoxia group; hypoxia group; LPS group; LPS plus hypoxia group (each group is provided with 3 duplicate holes). After treated with LPS(100 ng/ml), hypoxia group and LPS plus hypoxia group were placed in hypoxia cell incubator with 0.

Crystal Structures, Phase Stabilities, Electronic Properties, and Hardness of Yttrium Borides: New Insight from First-Principles Calculations.

Yttrium borides have attracted much attention for their superconducting and high chemical stability. However, the fundamental knowledge of the mechanical properties and hardness of yttrium borides is rather lack. Here, we performed a systematic investigation on yttrium borides with various stoichiometries based on an unbiased CALYPSO structure search method and first-principles calculations.

Self-passivation leads to semiconducting edges of black phosphorene.

The edges of black phosphorene (BP) have been extensively explored. The previous experimental observations that all the BP edges are semiconducting implies that the as-cut edges of BP tend to be reconstructed. Here we present a global structural search of three typical BP edges, namely armchair, zigzag and zigzag-1 edges.

Structures, Mobilities, and Electronic Properties of Functionalized Silicene: Superhalogen BO Adsorption.

The narrow band gap of silicene severely hinders its application in nanoelectronic devices. Therefore, it is significant to open the band gap of silicene and maintain its high carrier mobility. And for that, the adsorption of different coverage superhalogens BO on the silicene surface have been investigated based on density functional theory and the CALYPSO method.

Probing the structures, electronic and bonding properties of multidecker lanthanides: Neutral and anionic Ln(COT) (Ln = Ce, Nd, Eu, Ho and Yb; n, m = 1, 2) complexes.

The ground state structures of neutral and anionic Ln(COT) (Ln = Ce, Nd, Eu, Ho and Yb; n, m = 1, 2) complexes have been identified by density functional theory. Ln(COT) and Ln(COT) complexes are found to possess sandwich ground state structures in which Ln atoms and COT molecules are alternately stacked except for NdCOT. Our calculated AEA and VDE values show good agreement with the available experimental values, which validates that our obtained ground state structures are credible.

Prediction of hypervalent molecules: investigation on MC (M = Li, Na, K, Rb and Cs; n = 1-8) clusters.

New hypervalent molecules have emerged from a systematic exploration of the structure and bonding of MC (M = Li, Na, K, Rb and Cs; n = 1-8) clusters via an unbiased CALYPSO structure investigation combined with density functional theory. The global minimum structures are obtained at the B3LYP/6-311+G* and CCSD(T)/6-311+G* levels of theory. The observed growth behavior clearly indicates that the ground state of MC (M = Li, Na, K, Rb and Cs; n = 1-8) is transformed from a planar to a three-dimensional (3D) structure at n = 4.

Prediction of the Iron-Based Polynuclear Magnetic Superhalogens with Pseudohalogen CN as Ligands.

To explore stable polynuclear magnetic superhalogens, we perform an unbiased structure search for polynuclear iron-based systems based on pseudohalogen ligand CN using the CALYPSO method in conjunction with density functional theory. The superhalogen properties, magnetic properties, and thermodynamic stabilities of neutral and anionic Fe(CN) and Fe(CN) clusters are investigated. The results show that both of the clusters have superhalogen properties due to their electron affinities (EAs) and that vertical detachment energies (VDEs) are significantly larger than those of the chlorine element and their ligand CN.

Iron-based magnetic superhalogens with pseudohalogens as ligands: An unbiased structure search.

We have performed an unbiased structure search for a series of neutral and anionic FeL (L = BO, CN, NO, NO, OH, CH, NH, BH and LiH) clusters using the CALYPSO (Crystal structure Analysis by Particle Swarm Optimization) structure search method. To probe the superhalogen properties of neutral and anionic FeL clusters, we used density-functional theory with the B3LYP functional to examine three factors, including distribution of extra electron, pattern of bonding and the nature of the ligands. Theoretical results show that Fe(BO), Fe(NO) and Fe(NO) can be classified as magnetic superhalogen due to that their electron affinities even exceed those of the constituent ligands.

Investigation on the neutral and anionic BxAlyH2 (x + y = 7, 8, 9) clusters using density functional theory combined with photoelectron spectroscopy.

The structure and bonding nature of neutral and negatively charged BxAlyH2 (x + y = 7, 8, 9) clusters are investigated with the aid of previously published experimental photoelectron spectra combined with the present density functional theory calculations. The comparison between the experimental photoelectron spectra and theoretical simulated spectra helps to identify the ground state structures. The accuracy of the obtained ground state structures is further verified by calculating their adiabatic electron affinities and vertical detachment energies and comparing them against available experimental data.

Crystal Structures, Stabilities, Electronic Properties, and Hardness of MoB2: First-Principles Calculations.

On the basis of the first-principles techniques, we perform the structure prediction for MoB2. Accordingly, a new ground-state crystal structure WB2 (P63/mmc, 2 fu/cell) is uncovered. The experimental synthesized rhombohedral R3̅m and hexagonal AlB2, as well as theoretical predicted RuB2 structures, are no longer the most favorite structures.

Understanding the structural transformation, stability of medium-sized neutral and charged silicon clusters.

The structural and electronic properties for the global minimum structures of medium-sized neutral, anionic and cationic Sin(μ) (n = 20-30, μ = 0, -1 and +1) clusters have been studied using an unbiased CALYPSO structure searching method in conjunction with first-principles calculations. A large number of low-lying isomers are optimized at the B3PW91/6-311 + G* level of theory. Harmonic vibrational analysis has been performed to assure that the optimized geometries are stable.

Probing the structural and electronic properties of small aluminum dideuteride clusters.

Adsorption of deuterium on the neutral and anionic Aln(λ) (n=1-9, 13; λ=0, -1) clusters has been investigated systematically using density functional theory. The comparisons between the Franck-Condon factor simulated spectra and the measured photoelectron spectroscopy (PES) of Cui and co-workers help to search for the ground-state structures. The results showed that D2 molecule tends to be dissociated on aluminum clusters and forms the radial AlD bond with one aluminum atom.

Probing the geometries, relative stabilities, and electronic properties of neutral and anionic Ag(n)S(m) (n + m ≤ 7) clusters.

The geometry structures, relative stabilities, and electronic properties of neutral and anionic Ag(n)S(m) (n + m ≤ 7) clusters have been investigated systematically by means of density function theory (DFT). The results of geometry optimization show that the most stable configurations of binary Ag(n)S(m)⁰/⁻ clusters have an early appearance of 3D structure at n = 3, m = 1, differing from those of pure silver and sulfur clusters. Moreover, the ground-state structures prefer low spin multiplicity (singlet or doublet) except for S₂, Ag₂S₃, Ag₂S₄, Ag₄S₃, and Ag₂S₅.

Structural and relative stabilities, electronic properties, and hardness of iron tetraborides from first prinicples.

First-principles calculations were carried out to investigate the structure, phase stability, electronic property, and roles of metallicity in the hardness for recently synthesized FeB4 with various different structures. Our calculation indicates that the orthorhombic phase with Pnnm symmetry is the most energetically stable one. The other four new dynamically stable phases belong to space groups monoclinic C2/m, orthorhombic Pmmn, trigonal R3̅m, and hexagonal P63/mmc.