Structure and properties of linear polyethylene-montmorillonite nanocomposites

Nanocomposites based on PE and three types of montmorillonite are prepared by melt blending on a Brabender plastograph. The structure of hybrid materials is studied with the use of X-ray diffraction analysis and transmission electron microscopy. The type of modifier and the polarity of the polyolefin matrix affect the character of the filler structure (intercalated and exfoliated) formed during blending with the polymer. A correlation is found between the parameters of structural organization and the mechanical and barrier properties of nanocomposites. The tensile modulus of the nanocomposites containing 3?C5 wt % modified montmorillonite is 75% higher than that of the unfilled PE, whereas the time of combustion and the rate of flame propagation are 20 and 10% smaller, respectively.     

Structure and parameters of vacuum arc cathode spots

The effect of such parameters of cathode materials as the heat of atom evaporation, atomic weight, work function of electrons on the structure of cathode spots of a vacuum arc, conditions of charged particle generation, and, most important, the F-emission of electrons, is considered. Determining the interrelation of cathode parameters and processes in a vacuum arc cathode spot helps develop conditions for a vacuum arc to effectively modify the surfaces of materials.     

On the Pinsky Phenomenon

When n>2 it is well known that the spherical partial sums of n-fold Fourier integrals of a characteristic function of the ball D={x:|x|²<1} do not converge at the origin. In the mathematical literature this result is called “the Pinsky phenomenon”. In 1993 Pinsky established necessary and sufficient conditions for a piecewise smooth function, supported on D, which guarantee the convergence at the origin its spherical partial sums. We prove this result for nonspherical partial sums, i.e. for Fourier integrals under summation over domains bounded by level surfaces of elliptic polynomials.     

Triethoxysilane Express Analysis Method

Journal of Applied Spectroscopy - A technique for express analysis of triethoxysilane (TES), which is the main intermediate of chemical reactions occurring in silane synthetic processes, was...     

Analysis of Porous Nanosilicon by Raman Spectroscopy

Journal of Applied Spectroscopy - Technologies for the production of nanostructured silicon and porous nanosilicon are presented. A method for the synthesis of porous nanosilicon by electrochemical...     

On continuous wavelet transforms of distributions

Wavelet analysis is a universal and promising tool with very rich mathematical content and great potential for applications in various scientific fields, in particular, in signal (image) processing and the theory of differential equations. On the other hand distributions are widely used in these fields. And to apply wavelet analysis in these areas it is important to define and investigate wavelet transforms of distributions. In this paper we introduce continuous wavelet transforms of distributions and study convergence properties of these transforms.     

The Morphology and Electronic Properties of Si Nanoscale Structures on a CaF2 Surface

Technical Physics - The surface morphology, crystal structures, and band-energy parameters have been studied for nanofilms and regularly arranged nanoscale Si phases with a thickness of 1–2...     

Almost everywhere summability of multiple Fourier integrals

We obtain sufficient conditions for the Riesz means of spectral expansions converge to the function to be expanded.     

Conformational dimorphism in o‐nitrobenzoic acid: alternative ways to avoid the O…O clash

Polymorphism is a challenging phenomenon and the competitive packing alternatives which are characteristic for polymorphs may be encountered for essentially rigid molecules. A second crystal form of the well known compound o‐nitrobenzoic acid, C₇H₅NO₄, an important intermediate in the production of dyes, pharmaceuticals and agrochemicals, is described. Although obtained serendipitously, its intra‐ and intermolecular features match expectations from database searches and theoretical calculations. O—H…O hydrogen‐bonded carboxylic acid dimers represent the building blocks in both polymorphs. For steric reasons and in agreement with a calculated potential energy surface, the carboxylic acid and nitro groups cannot simultaneously be coplanar with the benzene ring but have to tilt. In the well established crystal form, this out‐of‐plane torsion is more pronounced for the nitro substituent. In contrast, the new polymorph is characterized by a major tilt of the carboxylic acid group. The molecules in both alternative crystal forms achieve a similar compromise with respect to acceptable intramolecular O…O contacts.