Convergence of series of dependent φ-subgaussian random variables

The almost sure convergence of weighted sums of φ-subgaussian m-acceptable random variables is investigated. As corollaries, the main results are applied to the case of negatively dependent and m-dependent subgaussian random variables. Finally, an application to random Fourier series is presented.     

Well Oriented ZnO Nanorods Array: Negative Resistance and Optical Switching

Well‐oriented ZnO nanorods (NRs) arrays were grown on Si, alumina, quartz, and FTO substrates through a ZnO seed layer followed by low temperature wet chemical process. The influence of sputtered ZnO seed layer thickness (100, 50, 32, and 16 nm), annealing temperature and CuO_x coverage on the characteristics of ZnO NRs were investigated in this study. The crystalline structural, chemical, morphological, optical, and electrical properties of ZnO NRs arrays were studied by X‐ray diffraction (XRD), field emission‐ scanning electron microscopy equipped by energy dispersive X‐ray spectroscopy (FE‐SEM/EDX), Raman scattering, UV/Vis ‐ near IR absorption spectroscopy and current‐voltage characteristic. XRD and Raman spectra measurement revealed that the synthesize ZnO displayed hexagonal wurtzite structure. The individual rod diameter, density, and orientation can be controlled by varying the seed layer thickness. The mean diameter and maximum length of ZnO NRs are around 55–66 nm and 282 nm, respectively. ZnO NRs/ ZnO thin film structure shows optical switching and negative differential resistance behavior as applicable to ON/OFF gate and memory devices.     

Viscosity based droplet size controlling in negative pressure driven droplets generator for large‐scale particle synthesis

The poor control and regulation of droplets limit the applications of negative pressure driven droplet generator (NPDDG). Here, we present a simple method to control droplet size in NPDDG via varying the oil viscosity. Depending on the infinite intersolubility of high viscous mineral oil and low viscous hexadecane, we obtain a series of oils with kinematic viscosities linearly varied from 4.2 to 194.6 mm²/s. By using these oils as continuous phases, monodisperse droplets are fabricated with controllable size in NPDDG. This viscosity‐based droplet regulation method is effective, reliable, and compatible with scale‐up processes. Compared with droplet generator driven by positive pressure, the presented method can fabricate hydrogel particles massively, without complicated multilayer chip structure and complex fluid controlling, which may extend the potential of NPDDG in droplets based high‐throughput assay or large‐scale materials synthesis.     

Snx[BPO4]1−x composites as negative electrodes for lithium ion cells: Comparison with amorphous SnB0.6P0.4O2.9 and effect of composition

A comparative study of two Sn-based composite materials as negative electrode for Li-ion accumulators is presented. The former SnB_0.6P_0.4O_2.9 obtained by in-situ dispersion of SnO in an oxide matrix is shown to be an amorphous tin composite oxide (ATCO). The latter Sn_0.72[BPO₄]_0.28 obtained by ex-situ dispersion of Sn in a borophosphate matrix consists of Sn particles embedded in a crystalline BPO₄ matrix. The electrochemical responses of ATCO and Sn_0.72[BPO₄]_0.28 composite in galvanostatic mode show reversible capacities of about 450 and 530 mAh g⁻¹, respectively, with different irreversible capacities (60% and 29%). Analysis of these composite materials by ¹¹⁹Sn Mössbauer spectroscopy in transmission (TMS) and emission (CEMS) modes confirms that ATCO is an amorphous Sn^II composite oxide and shows that in the case of Sn_0.72[BPO₄]_0.28, the surface of the tin clusters is mainly formed by Sn^II in an amorphous interface whereas the bulk of the clusters is mainly formed by Sn⁰. The determination of the recoilless free fractions f (Lamb-Mössbauer factors) leads to the effective fraction of both Sn⁰ and Sn^II species in such composites. The influence of chemical composition and especially of the surface-to-bulk tin species ratio on the electrochemical behaviour has been analysed for several Sn_x[BPO₄]_1−x composite materials (0.17<x<0.91). The cell using the compound Sn_0.72[BPO₄]_0.28 as active material exhibits interesting electrochemical performances (reversible capacity of 500 mAh g⁻¹ at C/5 rate).     

Energy dispersion relation for negative refraction (NR) materials

A general energy dispersion relation is developed for metamaterials having the negative-refraction (NR) property. It is shown that absorption effects are involved with NR phenomena, and the conditions under which NR occurs are discussed. Simple equations for NR are developed by using Lorentzian models.     

The use of trehalose in the preparation of specimens for molecular electron microscopy

Biological specimens have to be prepared for imaging in the electron microscope in a way that preserves their native structure. Two-dimensional (2D) protein crystals to be analyzed by electron crystallography are best preserved by sugar embedding. One of the sugars often used to embed 2D crystals is trehalose, a disaccharide used by many organisms for protection against stress conditions. Sugars such as trehalose can also be added to negative staining solutions used to prepare proteins and macromolecular complexes for structural studies by single-particle electron microscopy (EM). In this review, we describe trehalose and its characteristics that make it so well suited for preparation of EM specimens and we review specimen preparation methods with a focus on the use of trehalose.     

Comment on “Negative refraction in 1D photonic crystals” [Solid State Communications 147 (2008) 157-160]

It can be shown that negative refraction cannot occur in one-dimensional photonic crystals oriented as in Srivastava et al. (2008) [1].     

A PSDPF interaction to describe the 1 ?ω intruder states in sd shell nuclei

In the level schemes of sd shell nuclei, there is generally at relatively low excitation energies, coexistence of normal 0 ?ω positive parity states and of intruder 1 ?ω negative parity states. The aim of the present work is to describe these intruder states in the full p-sd-pf model space with a ⁴He core allowing one nucleon jump between the major shells. To construct our PSDPF interaction, we first modified the p-sd and sd-pf cross-monopole terms and then applied a fitting procedure to adjust all PSDPF parameters by comparing an extended set of experimental and calculated excitation energies. Results obtained with the new interaction have been finally compared with experimental data for nuclei throughout the sd shell.     

The electronic transport properties in C60 molecular devices with different contact distances

By applying non-equilibrium Green?s functions in combination with the density-functional theory, we investigate the transport behavior of molecular devices composed by metal electrode-C₆₀ molecule-metal electrode. Our results show that the electronic transport properties are affected obviously by the different contact distances between the electrodes, and the tunneling current decreases approximately exponentially at a certain bias with the increasing of contact distances. The negative differential resistance is observed and the peak-to-valley ratio can be tuned by different contact distances. The mechanisms of the contact distance effect and the negative differential resistance behavior are proposed.