Mechanical behavior of Cu-Zr bulk metallic glasses （BMGs）： A molecular dynamics approach

In the present work, three-dimensional molecular dynamics simulation is carried out to elucidate the nanoindentation behaviors of CuZr Bulk metallic glasses (BMGs). The substrate indenter system is modeled using hybrid interatomic potentials including both many-body Finnis Sinclair (FS) and two-body Morse potentials. A spherical rigid indenter (diameter = 60(1 = 10-10 m)) is employed to simulate the indentation process. Three samples of BMGs including Cu25Zr75 , Cu50Zr50 , and Cu75Zr25 are designed and the metallic glasses are formed by rapid cooling from the melt state at about 2000 K. The radial distribution functions are analyzed to reveal the dynamical evolution of the structure of the atoms with different compositions and different cooling rates. The mechanical behavior can be well understood in terms of load-depth curves and Hardness-depth curves during the nanoindentation process. Our results indicate a positive linear relationship between the hardness and the Cu concentration of the BMG sample. To reveal the importance of cooling rate provided during the processing of BMGs, we investigate the indentation behaviors of Cu50Zr50 at three different quenching rates. Nanoindentation results and radial distribution function (RDF) curves at room temperature indicate that a sample can be made harder and more stable by slowing down the quenching rate.     

Sub-ppt level voltammetric sensor for Hg2+ detection based on nafion stabilized l-cysteine-capped Au@Ag core-shell nanoparticles

Journal of Solid State Electrochemistry - Bimetallic nanoparticles (BMNPs) have received considerable attention due to their distinctive properties when compared to the corresponding monometallic...     

Optimization of process parameters and its effect on structure and morphology of CuO nanoparticle synthesized via the sol−gel technique

This article describes systematic basic research on the optimization of the processing parameters of sol?gel technique for synthesis of the high purity CuO nanoparticles. Effect of the synthesis parameters such as copper salt concentration, solvent and gelating agent, optimized one at a time, was investigated by employing XRD, TEM, FESEM, micro-Raman, UV-visible-NIR and PL spectroscopies. XRD results clearly demonstrate the monoclinic structure of CuO nanoparticles with traceable impurities at a lower molar concentration of Cu²⁺, transition of nucleation system from homogeneous to heterogeneous state with the increase in concentration of Cu²⁺ from 0.05 to 0.15?M. It was also found that the isopropyl alcohol offers better results in comparison to ethanol and water. Moreover, the lattice parameters, space group, and crystal system were determined by powder X-ray diffraction method. Further we propose the optimization of synthesis process using ethylene glycol and citric acid (EG:CA). The Raman analysis confirmed the influence of ethylene glycol and citric acid ratio and TEM observations confirmed that EG:CA 1:2 ratio formulate homogenous flower-like nanostructures. The optical absorption of CuO nanostructures can be easily tuned by varying the concentration of citric acid without changing other conditions; it shows the role of synthesis parameters more significant. Our results suggest that the prepared CuO nanostructures have a potential to be used as absorbing material in solar cell applications.

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2D hydrogen-bonded manganese–picolinate coordination network: ionic liquid-induced synthesis,crystal structure and thermogravimetric analysis

A new manganese coordination complex of formula [Mn(2-picolinate)₂·2H₂O]·H₂O based on 2-picolinic acid has been synthesized hydrothermally at 120 °C for 48 h in presence of ionic liquid tetraethylammonium hydroxide (25% methanolic solution). 1 crystallizes in monoclinic crystal system and is hydrogen-bonded metal-organic network in which aqua ligands are instrumental in deciding structural features. The reported complex 1 is insoluble in almost all organic solvents as well as in water and shows good thermal stability upto 450 °C.     

Silanylidene and Germanylidene Anions: Valence‐Isoelectronic Species to the Well‐Studied Phosphinidene

The reduction of TipMCl₃ (Tip=2,4,6‐triisopropylphenyl) (M=Si, Ge) with KC₈ in the presence of cyclic alkyl(amino) carbene (cAAC) afforded the acyclic silanylidene and germanylidene anions in the form of potassium salt [K(cAAC)MTip]₂ (M=Si ( 1 ); Ge ( 2 )). The silanylidene and germanylidene anions are valence‐isoelectronic to the well‐studied phosphinidene and are a new class of acyclic anions of Group 14. Compounds 1 and 2 were isolated and well characterized by NMR and single‐crystal X‐ray structure analysis. Furthermore, the structure and bonding of compounds 1 and 2 was investigated by computational methods.     

Electronic and optical properties of quaternary selenides for optoelectronic applications: Insights from DFT+U-computations

The optical properties, electronic charge density, electronic structure of the new layered selenides materials, BaGdCuSe₃, CsUCuSe₃, CsZrCuSe₃, and CsGdZnSe₃ compounds have been calculated by using the full potential and linear augmented plane wave (FP-LAPW) methods as applied in the WIEN2k package, which is based on the density functional theory. The ALnMSe3 compound's structure of these was (A = Cs, Ba; Ln = Zr, Gd, U; M = Cu, Zn) is composed of (n = 1, 2) layers, which might be separated by A atoms. It is to be observed that there is strong hybridization between the s, p, and d states of Zr, Gd, and Cu atoms. Around the gadolinium atom, the charge density contours are completely circular, but the Gadolinium “Gd” atom shows an ionic nature. To calculate the refractive index, we used Kramer's Kronig correlations with the imaginary part dielectric function. The decrease in the refractive index is due to the lack of probability for direct excitation of the electrons, resulting in a loss of energy. The value of the static refractive index for all reference compounds is about 1.75–2.25, which is indication that the material used in optoelectronic devices.     

Comprehensive structural studies of 2',3'-difluorinated nucleosides: comparison of theory, solution, and solid state

The conformations of three 2',3'-difluoro uridine nucleosides were studied by X-ray crystallography, NMR spectroscopy, and ab initio calculations in an attempt to define the roles that the two vicinal fluorine atoms play in the puckering preferences of the furanose ring. Two of the compounds examined contained fluorine atoms in either the arabino or xylo dispositions at C2' and C3' of a 2',3'-dideoxyuridine system. The third compound also incorporated fluorine atoms in the xylo configuration on the furanose ring but was substituted with a 6-azauracil base in place of uracil. A battery of NMR experiments in D 2O solution was used to identify conformational preferences primarily from coupling constant and NOE data. Both (1)H and (19)F NMR data were used to ascertain the preferred sugar pucker of the furanose ring through the use of the program PSEUROT. Compound-dependent parameters used in the PSEUROT calculations were newly derived from complete sets of conformations calculated from high-level ab initio methods. The solution and theoretical data were compared to the conformations of each molecule in the solid state. It was shown that both gauche and antiperiplanar effects may be operative to maintain a pseudodiaxial arrangement of the C2' and C3' vicinal fluorine atoms. These data, along with previously reported data by us and others concerning monofluorinated nucleoside conformations, were used to propose a model of how fluorine influences different aspects of nucleoside conformations.     

Cavity QED based tuneable,delayed-choice quantum eraser

We propose an experimentally feasible idea for the delayed-choice quantum eraser, having adjustable path distinguishability/fringe visibility. The schematics are based on resonant, dispersive and Ramsey interactions of atoms under cavity QED scenario. The option for tuneability of the fringes in a delayed-choice setup stringently marks the conception of the time in the quantum theory, operational meanings of the state vector reduction and raises questions about Ψ$\Psi$-ontic models while helping to shed out the controversies surrounding the quantum eraser theme. The proposal can be efficiently executed experimentally within the prevailing cavity QED experimental research scenario with good overall success probability and fidelity.     

PVP Assisted Shape-Controlled Synthesis of Self-Assembled 1D ZnO and 3D CuO Nanostructures

Self-assembled one-dimensional (1D) zinc oxide (ZnO) rods and three-dimensional (3D) cupric oxide (CuO) cubes like nanostructures with a mean crystallite size of approximately 33 and 32 nm were synthesized through chemical route in the presence of polyvinylpyrrolidone (PVP) under mild synthesis conditions. The technique used for the synthesis of nanoparticles seems to be an efficient, inexpensive and easy method. X-Ray diffraction patterns confirmed well crystallinity and phase purity of the as prepared samples, followed by the compositional investigation using Fourier Transform Infrared (FT-IR) spectroscopy. The formation of ZnO nanorods and CuO nanocubes like structures were through Scanning Electron Microscopy (SEM) images. The mechanism and the formation factors of the self-assembly were discussed in detail. It was clearly observed from results that the concentration of precursors and PVP were important factors in the synthesis of self-assembly ZnO and CuO nanostructures. These self-assembly nanostructures maybe used as novel materials in various potential applications.