Size matters: Nanometer‐sized gaps in aggregates of silver nanoparticles are generated by covering the nanoparticle surface with a bilayer of cetyltrimethylammonium bromide. The nanometer‐ to micrometer‐sized wells are lithographically generated on polydimethylsiloxane surfaces. The wells filled with the modified nanoparticles (see picture) and the effect of the aggregate size on SERS enhancement are investigated.
The kinetics of a proton transfer into dilute acid solutions containing natural zeolitic tuff was studied by following the
pH evolution of the liquid phase. Four different solutions with tuff contents of 9, 3, 1 and 0.5 (% wt) and three different
particle size fractions (≤ 2000 μm) were studied. The proton concentration of the solution was decreased by increasing the
zeolite amount and decreasing the particle size fraction. The proton transfer reaction was analyzed with chemical reactions
and diffusion model equations. Analysis shows that the adsorption and/or ion exchange are possible mechanisms and are expressed
by a second order reaction model. 相似文献
The structural and lattice dynamical properties of TmX (X=As, P) compounds were investigated using normconserving pseudopotentials within the generalized gradient approximation correction (GGA) of Perdew–Burke–Ernzerhof (PBE) in the framework of density functional theory (DFT). The structural parameters (a0, B, B′, Ecoh) were determined through total energy and interatomic force minimization and the overall agreement was found to be good. The pressure dependence of the ratios of normalized lattice parameters a/a0, normalized volume V/V0, bulk modulus, elastic constants, Zener anisotropy factor, Poisson's ratio, Young's modulus, shear modulus, and the brittleness were presented and discussed. The thermodynamical properties such as thermal expansion, heat capacity, Debye temperature, and Grüneisen parameter were calculated employing the quasi-harmonic Debye model at different temperatures (0–1000 K) and pressures (0–30 GPa). The phonon dispersion curves and corresponding density of states (DOS) of TmX (X=As, P) were also obtained, and the salient results were interpreted. 相似文献
The crystal structure of hexakis(4-phormylphenoxy)cyclotriphosphazene is determined by using X-ray diffraction and then the
molecular structure is investigated with density functional theory (DFT). X-Ray study shows that the title compound has C-H…π
interaction with phosphazene ring. The molecules in the unit cell are packed with Van der Waals and dipole-dipole interactions
and the molecules are packed in zigzag shaped. Optimized molecular geometry is calculated with DFT at B3LYP/6-311G(d,p) level.
The results from both experimental and theoretical calculations are compared in this study. 相似文献
A new compound of (C27H25N3S) has been synthesized and characterized by 1H NMR, 13C NMR, IR, UV-Visible spectroscopy, and single crystal X-ray diffraction. The compound crystallizes in the monoclinic space
group P21/c and crystals of (I) were found approximately 0.5:0.5 ratio to be twinned. The crystal structure is stabilized by N–H···N
inter molecular hydrogen bonding. In addition to the molecular geometry and dimeric structure from X-ray experiment, the optimized
molecular geometry for monomer and dimer, vibrational frequencies, atomic charges distribution, and total energies of the
title compound in the ground state have been calculated using ab initio method. Density Functional Theory (B3LYP) and Hartree-Fock
(HF) methods with basis sets 6-31G(d, p) and 3-21G were used in the calculations. Calculated frequencies are in good agreement
with the corresponding experimental data. UV-Vis absorption spectra of the compound have been ascribed to their corresponding
molecular structure and electrons orbital transitions. 相似文献
In this study, Darcy Forchheimer flow paradigm, which is a useful paradigm in fields such as petroleum engineering where high flow velocity effects are common, has been analyzed with artificial intelligence approach. In this context, first of all, Darcy–Forchheimer flow of Ree–Eyring fluid along a permeable stretching surface with convective boundary conditions has been examined and heat and mass transfer mechanisms have been investigated by including the effect of chemical process, heat generation/absorption, and activation energy. Cattaneo–Christov heat flux model has been used to analyze heat transfer properties. Within the scope of optimizing Darcy–Forchheimer flow of Ree–Eyring fluid; three different artificial neural network models have been developed to predict Nusselt number, Sherwood number, and skin friction coefficient values. The developed artificial neural network model has been able to predict Nusselt number, Sherwood number, and skin friction coefficient values with high accuracy. The findings obtained as a result of the study showed that artificial neural networks are an ideal tool that can be used to model Darcy–Forchheimer Ree–Eyring fluid flow towards a permeable stretch layer with activation energy and a convective boundary condition. 相似文献