Materials Literature
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Abstract PTFE surfaces have been exposed to neutral atoms and molecules, and to electrons originating from a modified RF nitrogen plasma, able to filter out the cations. The changes in surface energy of the modified polymer, determined by the water contact angle, are linearly related to the increase of the nitrogen co…
Novel Ag on TiO2 films are generated by semiconductor photocatalysis and characterized by ultraviolet-visible (UV/Vis) spectroscopy, scanning electron microscopy (SEM), and atomic force microscopy (AFM), as well as assessed for surface-enhanced Raman scattering (SERS) activity. The nature and thickness of the photodep…
Abstract Several 2- and 3-(phenylazo)pyridine derivatives were prepared. Most of their trans isomers have a large absorption band (∼2 × 104 M−1 cm−1 (1 M = 1 mol dm−3)) around 320 nm and a small absorption band (∼400 M−1 cm−1) around 450 nm. All of these compounds photoisomerize upon irradiation of the shorter (trans-…
Abstract— We studied the infrared reflectance (IR), Raman, and cathodoluminescence (CL) spectroscopic signatures and scanning electron microscope‐cathodoluminescence (SEM‐CL) images of three different types of impact glasses: Aouelloul impact glass, a Muong Nong‐type tektite, and Libyan desert glass. Both backscattere…
The oxidation behavior of SiCN–ZrO 2 fibers and SiCN at 1350°C are compared. The as‐measured parabolic rate constants for the two materials are nearly the same (15–20 × 10 −18 m 2 /s). However, after implementing a correction for the difference in the compositions, the rate constant is 13.2 × 10 −18 m 2 /s for the fib…
Preliminary research has shown that triboluminescent (TL) phosphors show promise for use as the active element in impact sensors. For ZnS:Mn, preliminary results indicate that impact energies greater than 1.6/spl times/10/sup -2/ J produced measurable TL light. A so-called "smart" structure with embedded TL material c…
We have investigated the antiferromagnetic (AF) resonance modes (AFMR) of NiO, theoretically using a model that includes the effects of exchange, dipolar coupling, and a small cubic anisotropy, and experimentally using Brillouin scattering. Using only superexchange between next nearest Ni atoms the model accounts for…
Peridotite soils were perceived to be redder than serpentinite soils. These redness differences were confirmed by relating soil redness to bedrock specific gravities and to heavy mineral concentrations in fine sand fractions of soils. The redness differences are explained by mineralogical differences between peridotit…
This is the first of a two-part series on the chemical, morphological, and electrical changes of polydimethylsiloxane (PDMS) and alumina trihydrate (ATH) material system subjected to dry-band discharges produced on the material surface by sustained moisture and contamination buildup. This system possesses both stable…
A silicon diimide gel Si(NH) x (NH 2 ) y (NMe 2 ) z was prepared by an acid‐catalyzed ammonolysis of tris(dimethylamino)silylamine. Pyrolysis of the gel at 1000°C under NH 3 flow led to the formation of an amorphous silicon nitride material without carbon contamination. All of the gel and pyrolyzed products exhibited…
A comprehensive model is presented to study the deformation of and damage to woven fabrics under small projectile impacts. The approach dynamically follows the strain wave propagation along each individual yarn away from the impact point. As in previous work, the mechanics of wave propagation is formulated in terms of…
Two modeling methods are used to predict the tensile properties of air-jet spun yarns. A numerical simulation provides a useful insight into the flow characteristics and wrap ping formation process of edge fibers in the nozzle of an air-jet spinning machine. By analyzing the results of the numerical simulation, the ef…
Abstract The two new compounds Mn 2 (L)Sb 2 S 5 (L = diethylenetriamine = DIEN, N-methyl-1,3- diaminopropane = MDAP) were prepared under solvothermal conditions using the elements as starting materials. Both compounds crystallise in the monoclinic space group P2 1 /c with the lattice parameters a=10.669(7), b=12.805(2…
A new method is proposed for the treatment of Raman spectra of amorphous-nanocrystalline silicon films serving as a major component in solar cells. The method is based on the well-known theory of strong spatial localization (confinement) of phonons and offers the possibility of estimating the fractional content of the…
We describe a technique for measuring heat capacities (Cmin≈1 μJ/K at 0.1 K) of small solid samples at low temperatures (0.03 K<T<6 K) and in high magnetic fields (B<12 T). In this compensated heat-pulse technique the thermal losses are compensated through a background heating. A detailed analysis…
The purpose of this study was to investigate the degradation in performance of four major alloys of orthodontic wires, namely nickel-titanium, beta titanium, stainless steel, and cobalt-chromium-nickel, caused by hydrogen absorption during short-term immersion in an acid fluoride solutions. The hydrogen-related degrad…
The effect of chitosan on the growth and morphology of Fusarium oxysporum f. sp. albedinis (Foa), the causal agent of Bayoud disease, and its ability to elicit a defence reaction against this fungus in date palm roots were investigated. Chitosan at 1 mg ml-1 reduced the growth of Foa on potato dextrose agar medium by…
In this work, a model based on field criterion has been developed to represent the flashover phenomenon, which occurs due to surface pollution on high voltage insulators, under ac voltage. The values of potential and electric field on an insulator surface have been determined using the finite element method (FEM). The…
Abstract Two samples of isotactic polypropylene (iPP) representing the crystalline α‐ and β‐modifications are compared with regard to their semicrystalline morphology and the resulting micromechanical mechanisms. Processes at room temperature (23°C) and at −40°C have been investigated by means of different microscopic…
A mean-field theory for the geometry and diffusive growth rate of soap bubbles in dry 3D foams is presented. Idealized foam cells called isotropic Plateau polyhedra (IPPs), with F identical spherical-cap faces, are introduced. The geometric properties ( e.g. , surface area S , curvature R , edge length L , volume V )…