Salts are Mostly NOT Ionized
The popular assumption that all salts are totally ionized in aqueous solution is false. Moreover, it is approximated only by alkali metal salts and by salts of alkaline earth metals with high atomic numbers.
Materials Literature
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Diffusion of Aroma Compounds into Packaging Films under High Pressure
Diffusion of the aroma compounds p-cymene and acetophenone into three different packaging films was studied at 500 MPa for kinetic measurement, and in the range of 0.1–450 MPa for measurement of the diffusion rate as a function of pressure. Absorption of aroma compounds was lower in pressurized than in nonpressurized…
Polymorphism of Extended Fullerene Networks: Geometrical Parameters and Electronic Structures
The morphology of fullerene networks can be widely extended by introducing heptagonal or octagonal rings, which produce a Gaussian negative curvature. Their presence makes it possible to form donut-, coil- and sponge-shaped networks of carbon atoms. We discuss the geometry of the polymorphous forms based on the net di…
Polybenzimidazoles, new thermally stable polymeres
Wholly aromatic polybenzimidazoles were synthesized from aromatic tetraamines and difunctional aromatic acids and characterized as new thermally stable polymers. The melt polycondensation of aromatic tetraamines and the diphenyl esters of aromatic dicarboxylic acids was developed as a general procedure of wide applica…
Highly precise non-contact instrumentation for magnetic measurement of mechanical stress in low-carbon steel wires
The magnetoelastic properties of steel wires are used for measuring a mechanical load in tension. A microcomputer-controlled measuring instrument was designed. The dependence of magnetic behaviour on a previous state is eliminated by the suggested method of commutated measurement of amplitude permeability from saturat…
Flow patterns and disclination-density measurements in sheared nematic liquid crystals II: Tumbling 8CB
We examine the behaviour of nematic 4,4′-n-octylcyanobiphenyl (8CB) subjected to steady torsional shear flow at a temperature where this nematic is ‘tumbling’, i.e. the ratio α3/α2 of Leslie viscosities is negative. If the disc rotation speed is gradually increased from zero ( < 10−6 rad s−2), the director eventually…
<title>Applications of torsional shape memory alloy actuators for active rotor blade control: opportunities and limitations</title>
A shape memory alloy rod, if it is pre-twisted to create stress induced martensitic transformation, will exhibit a torsional shape memory effect, namely, some of the pre-twist will be recovered once the SMA rod is heated above its austenitic start temperature. If the pre- twisted SMA rod is constrained, a large recove…
Stretched-exponential relaxation modeled without invoking statistical distributions
Relaxation phenomena in disordered systems are often described by stretched exponentials; such behavior has traditionally been explained by invoking statistical distributions. In hydrogenated amorphous silicon, the relaxation has been associated with dispersive diffusion of hydrogen, related to a distribution of energ…
The Powder Diffraction file: Past, present, and future
data along with the appropriate crystallographic, physical and experimental information. This paper reviews the development and growth of the PDF and discusses the role of the ICDD in the maintenance and dissemination of the file.
Thermodynamics of the Si‐O‐N System: II, Stability of Si 2 N 2 O(s) by High‐Temperature Mass Spectrometric Vaporization
The Si 2 N 2 O(s) compound is vaporized in a multiple Knudsen‐cell connected to a mass spectrometer. Comparison of SiO(g) and N 2 (g) pressures between different samples in the Si‐N‐O system, as triphasic or diphasic mixtures from Si(s), Si 3 N 4 (s), and Si 2 N 2 O(s), allows the determination of the SiO(g) evaporati…
Electron inelastic mean free path and stopping power modelling in alkali halides in the 50 eV–10 keV energy range
A model for calculating the electron inelastic mean free path and stopping power in insulators in the 50 eV–10 keV energy range is presented. Both valence and core electron contributions have been considered. The valence part has been estimated following the dielectric theory modified to include the energy gap; the co…
A model for thin film texture evolution driven by surface energy effects
Abstract A model was developed in order to calculate the texture evolution of a growing film with large atomic diffusion on the surface. The tendency for lowest surface energy was taken as the driving force for the evolution. The orientation dependent surface energy y was approximated by a function with a sharp minimu…
Flow patterns and disclination-density measurements in sheared nematic liquid crystals I: Flow-aligning 5CB
We report the first direct measurements of disclination density during shear flow of a nematic liquid crystal. Samples of 4,4′-n-pentylcyanobiphenyl, or 5CB, are initially aligned in the homeotropic configuration within a torsional shear cell using surface treatment with lecithin. For low shearing rates, the director…
Optical-DC-Field Induced Space Charge Fields and Photorefractive-Like Holographic Grating Formation in Nematic Liquid Crystals
We present a detailed theoretical discussion of the fundamental mechanisms for dc field assisted optically induced space charge fields and molecular reorientation effects in nematic liquid crystal films. In fullerene C60-doped film, persistent director axis reorientation is observed, allowing the recording of holograp…
Cynanchum – Rhodostegiella – Vincetoxicum – Tylophora (Asclepiadaceae): new considerations on an old problem
Summary Liede, S.: Cynanchum – Rhodostegiella – Vincetoxicum – Tylophora (Asclepiadaceae): new considerations on an old problem. – Taxon 45: 193‐211. 1996. – ISSN 0040‐0262. On the basis of morphological and chemical data, the genus Vincetoxicum is recognized as separate from Cynanchum. Tylophora is identified as the…
Influence of one-fold-coordinated atoms on mechanical properties of covalent networks
One-fold-coordinated atoms in a covalent network mechanically soften a network if it is overcoordinated, and conversely, mechanically stiffen the network if it is undercoordinated. They play no part in network rigidity if the network is optimally coordinated. These features follow directly from constraint theory and p…
Low-Velocity Perforation of Punch-Impact-Loaded Metal Plates
An approximate quasi-static theoretical analysis is presented for the behavior of punch-impact-loaded metal plates. Based on the principle of virtual work, load-deflection relationships are first obtained and then used to predict the energy-absorbing capabilities of plates subjected to low-velocity impacts that cause…
Orientation of triblock copolymers in planar extension
Abstract Three commercial styrenic triblock copolymers were subjected to planar extension in a lubricated channel die, as a model for the orientation that may occur during processing operations. Materials that contain cylinders of polystyrene show a pronounced orientation of the cylinder axis in the flow direction, as…
Highly Selective Adsorption Resins. I. Preparation of Chitosan Derivatives Containing 2-Pyridylmethyl, 2-Thienylmethyl, and 3-(Methylthio)propyl Groups and Their Selective Adsorption of Precious Metals
Abstract Crosslinked N-(2-pyridylmethyl)chitosan, N-(2-thienylmethyl)chitosan, and N-[3-(methylthio)propyl]chitosan were newly synthesized. The amino group of the active adsorption site of chitosan was protected by Schiff’s base formation prior to being crosslinked by 2-(chloromethyl)oxirane. The final chitosan deriva…
A time-resolved current method for the investigation of charging ability of insulators under electron beam irradiation
In the present article, a convenient method for the direct measurement of the displacement current caused by electron trapping is developed to measure the trapped charge in insulators under electron beam irradiation from a scanning electron microscope. The trapping process during electron beam irradiation can be direc…