Deep Charge: A Deep Learning Model of Electron Density from One-Shot Density Functional Theory Calculation

Electron charge density is a fundamental physical quantity, determining various properties of matter. In this study, we have proposed a deep-learning model for accurate charge density prediction. Our model naturally preserves physical symmetries and can be effectively trained from one-shot density functional theory calculation toward high accuracy. It captures detailed atomic environment information, ensuring accurate predictions of charge density across bulk, surface, molecules, and amorphous structures. This implementation exhibits excellent scalability and provides efficient analyses of material properties in large-scale condensed matter systems

Ionic Liquid-assisted Synthesis of Polyaniline/Gold Nanocomposite and Its Biocatalytic Application

In this report, a novel chemical synthesis of polyaniline/gold nanocomposite is explored using ionic liquid (IL) 1-Butyl-3-methylimidazolium hexafluorophosphate. The direct chemical synthesis of polyaniline/gold nanocomposite was initiated via the spontaneous oxidation of aniline by AuCl4−in IL. A nearly uniform dispersion of polyaniline/Au particles with a diameter of 450 ± 80 nm was produced by this method, which indicates that this method is more suitable for controlling particle dimensions. It was also found that the electrical conductivity of the polyaniline/gold nanocomposite was more than 100 times higher than that of the pure polyaniline nanoparticles. The polyaniline/gold nanocomposite displays superior function in the biocatalytic activation of microperoxidase-11 because of the high surface area of the assembly and the enhanced charge transport properties of the composite material. We also report the possible application of polyaniline/gold nanocomposite as a H2O2biosensor

In Vitro Studies of Cells Grown on the Superconductor PrOxFeAs

The recent discovery of arsenic-based high temperature superconductors has reignited interest in the study of superconductor : biological interfaces. However, the new superconductor materials involve the chemistry of arsenic, their toxicity remain unclear [ Nature, 2008, 452(24):922]. In this study the possible adverse effects of this new family of superconductors on cells have been examined. Cell culture studies in conjunction with microscopy and viability assays were employed to examine the influence of arsenic-based superconductor PrOxFeAs (x=0.75) material in vitro. Imaging data revealed that cells were well adhered and spread on the surface of the superconductor. Furthermore, cytotoxicity studies showed that cells were unaffected during the time-course of the experiments, providing support for the biocompatibility aspects of PrOxFeAs-based superconductor material.Comment: Are the FeAs based superconductors toxic

Using soft lithography to pattern highly oriented polyacetylene (HOPA) films via solventless polymerization

A new application of the combination of soft lithography and solventless polymerization is described (see Figure)-the patterning of ultra-hard microstructures in selected areas using highly oriented polyacetylene (HOPA) films as a precursor. It is expected that this simple, low-cost, and mild process will lead to the formation of highly oriented films of other materials, e.g., electro-optically active polymers

Giant exchange bias and the vertical shifts of hysteresis loops in gamma-Fe2O3-coated Fe nanoparticles

We fabricated core/shell-structured Fe nanoparticles, in which the alpha-Fe core is about 5 nm in diameter and the gamma-Fe2O3 shell is about 3 nm thick, and systematically studied their structural and magnetic properties. The magnetic hysteresis (M-H) loops, measured at low temperatures, after the particles were cooled from 350 K in a 50 kOe field, show significant shifts in both horizontal and vertical directions. It has been found that the exchange-bias field can be as large as 6.3 kOe at 2 K, and that the coercive field is also enhanced greatly in the field-cooled (FC) loops. The large exchange bias and vertical shifts of the FC loops at low temperatures may be ascribed to the frozen spins in the shells. A simple model is proposed to interpret the observations. (C) 2004 American Institute of Physics

Performance modulation of a-MnO2 nanowires by crystal facet engineering

Modulation of material physical and chemical properties through selective surface engineering is currently one of the most active research fields, aimed at optimizing functional performance for applications. The activity of exposed crystal planes determines the catalytic, sensory, photocatalytic, and electrochemical behavior of a material. In the research on nanomagnets, it opens up new perspectives in the fields of nanoelectronics, spintronics, and quantum computation. Herein, we demonstrate controllable magnetic modulation of α-MnO 2 nanowires, which displayed surface ferromagnetism or antiferromagnetism, depending on the exposed plane. First-principles density functional theory calculations confirm that both Mn- and O-terminated α-MnO2(1 1 0) surfaces exhibit ferromagnetic ordering. The investigation of surface-controlled magnetic particles will lead to significant progress in our fundamental understanding of functional aspects of magnetism on the nanoscale, facilitating rational design of nanomagnets. Moreover, we approved that the facet engineering pave the way on designing semiconductors possessing unique properties for novel energy applications, owing to that the bandgap and the electronic transport of the semiconductor can be tailored via exposed surface modulations

The Behavior of gallium confined in carbon nanotubes during heating and cooling

The thermal expansion of gallium (Ga) encapsulated in carbon nanotubes has been studied. It is demonstrated that the volumetric expansion and contraction of the Ga confined in the carbon nanotubes display a linear relationship with temperature. While the level of the tip of the Ga column changes linearly with temperature, it returns to its previous position, without any hysteresis, when reheated or cooled to the original temperature, provided the Ga has not frozen and electron-beam irradiation is minimized. It is shown that electron beam irradiation can cause shrinkage in carbon-nanotube diameter, and that a high-intensity electron beam can also induce the formation of new carbon shells inside the carbon nanotubes. Upon freezing, the solid Ga has two unique orientation relationships with the carbon nanotubes.4 page(s

Low temperature spin-glass-like phases in magnetic nano-granular composites

It is a common understanding that the dipole-dipole interaction among the magnetic nanoparticles may result in a low-temperature spin-glass phase, which has been evidenced by observation of aging effect and memory effect. However, several studies on the nano-particles systems showed that some of the observed spin-glass-like phenomena could be due to the existence of spin-glasslike shells surrounding the ferrimagnetic cores. Therefore, it is very important to understand that how the dipole-dipole interaction induce the spin-glass phase. In order to address this issue, we have fabricated Co-SiO 2 and Fe-SiO 2 nano-granular thin films and measured the memory effect for them. Spin-glass-like phase has been observed at low temperatures. We found that, after annealing, the size of the clusters increased significantly. Based on a simple model, the dipole-dipole interaction between the clusters must be increased accordingly for the annealed samples. Interestingly, the memory effect is greatly weakened in the annealed films, which strongly suggested that the dipole-dipole interaction may not be the major factor for the formation of the low-temperature spin-glass-like phase. Copyright © 2012 American Scientific Publishers All rights reserved