Bis-1,3-dithiolium chloride: an unusually stable organic radical cation
Treatment of bis-1,3-dithiole with 1 equiv. of chlorine affords a very stable radical cation which is amenable to full chemical and spectroscopic characterization.
Materials Literature
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A Reinterpretation of Organic Liquid-Polytetrafluoroethylene Surface Interactions
The wettability of polytetrafluoroethylene (PTFE) by organic liquids is reanalyzed in terms of dispersion-polar interactions across the liquid-solid interface. The analysis provides values of γs d = 19.6 dyne/cm, and γS D = 2.0 dyne/cm for the respective dispersion and polar parts of the surface tension γs = 21.6 for…
The temperature and strain-rate dependence of the shear strength of mild steel
An account is given of experiments in which the shear flow stress of mild steel was measured at temperatures from 195 to 713°K and strain rates from 10−3 to 4 × 104 sec−1. The experimental results obtained at room temperatures are compared with those of earlier tension tests. The rate sensitivity of the flow stress, (…
Stress tensor for a nematic liquid crystal
Constitutive equations for nematic liquid crystals were first established by Ericksen and Leslie. They used a stress tensor with six viscosity coefficients αi (i = 1...6). It is shown in this paper that the Onsager reciprocal relations lead to the relation α2 + α 3 = α6 - α5 . Hence there are only five independent vis…
Small Gaussian Expansions of Slater-Type Orbitals
Small Gaussian expansions of Slater-type orbitals by the method of least squares are presented. Expansion lengths are from one to six. Slater-type orbitals 1s through 5g are included. The least-squares equations were solved by a full-matrix method. Expectation values, r−2, r−1, r, and r2 for the several expansions are…
Atomic vibrations in vitreous silica
Frequency spectra and normal modes of vibration have been computed for vitreous silica. They have been calculated from atomic arrangements in physical models based on the random network theory. The positions of bands in the computed spectra agree well with observed features in the experimental infra-red and Raman spec…
Alumina as a ceramic material
INTRODUCTION. NOMENCLATURE. PREPARATION OF ALUMINA PHASES. Bauxite. Preparation of Bayer Alumina. Wet Alkaline Processes. Wet Acid Processes. Furnace Processes. Carbothermic Processes. Electrolytic Processes. Amorphous and Gel Aluminas. Preparation of the Alumina Trihydroxides. Gibbsite. Bayerite. Nordstrandite, Bayer…
Handbook of Tables for Applied Engineering Science
New tables in this edition cover lasers, radiation, cryogenics, ultra-sonics, semi-conductors, high-vacuum techniques, eutectic alloys, and organic and inorganic surface coating. Another major addition is expansion of the sections on engineering materials and compos-ites, with detailed indexing by name, class and usag…
The Coordination Number – an “Inorganic Chameleon”
Abstract The purpose of the present article is to describe the changing ambiguous character of the term “coordination number” and its present‐day definition in structural chemistry, particularly of typical solids (assemblies of particles with short‐range and long‐range order). An effort is made at the same time to des…
Small-polaron versus band conduction in some transition-metal oxides
In this paper an attempt is made to establish the nature of free charge carriers and of charge carriers bound to centres in p-type NiO, CoO and MnO and in n-type MnO and α-Fe2O3. For free charge carriers, d.c. conductivity, Seebeck coefficient and Hall effect are considered. Effects arising from inhomogeneous conducti…
Theory of magnetic suspensions in liquid crystals
The present paper discusses some properties of small, elongated particles suspended in a nematic or cholesteric phase, with low concentrations (typical volume fraction occupied by the particle f ≊ 10-3). We find that in most cases the particle axis should be locked and parallel to the local nematic axis n(r). If such…
A Novel Principle of the Computation of Stress Intensity Factors
A state of plane strain in a notched or cracked elastic domain under the action of boundary tractions is considered. It is shown that the stress intensity factor K at a root of a notch can be re presented in the form of a weighted average of the tractions, and that the weight functions involved can be derived from the…
A Statistical Theory of Solid Solution Hardening
Abstract The critical shear stress τ c to move a dislocation through a random array of obstacles in the glide plane is calculated using a statistical theory. The result is an expression for τ c in terms of the obstacle concentration, the line tension of the dislocation, and of the interaction force between the disloca…
Non-symmetrical dielectric relaxation behaviour arising from a simple empirical decay function
The empirical dielectric decay function γ(t)= exp –(t/τ0)β may be transformed analytically to give the frequency dependent complex dielectric constant if β is chosen to be 0.50. The resulting dielectric constant and dielectric loss curves are non-symmetrical about the logarithm of the frequency of maximum loss, and ar…
Zur weiteren Kenntnis des Chlorophylls und des Hämins, XXX1) Photoprotoporphyrine und ihre Umwandlung in Spirographis‐ sowie Isospirographis‐porphyrin2)
Abstract Das durch Einwirkung von Licht und Sauerstoff auf Protoporphyrin‐IX‐dimethylester (1a) entstehende Photoprotopophyrin wird chromatographisch in zwei Isomere getrennt. Spektroskopische Daten und chemische Reaktionen beweisen hierfür die Strukturen 2 und 3 . Reduktion, Umlagerung und anschließende Glykolspaltun…
The Fermi surfaces of the noble metals
Abstract Precision measurements of the angular dependence of the de Haas-van Alphen frequencies F (proportional to extremal areas of the Fermi surface) of the noble metals have been made, using the technique of following the oscillations in magnetic properties as the crystal is slowly rotated in a fixed magnetic field…
Method of Complex Coordinates for Three-Body Calculations above the Breakup Threshold
A method is proposed for calculating elastic and inelastic three-particle scattering amplitudes in the breakup region using a coordinate-space variational approach, with each coordinate multiplied by a complex phase factor. The trial wave functions have relatively simple asymptotic forms. The method applies to short-r…
Localization of Antigenic Determinants in the Polypeptide Chains of Collagen
After being injected with collagen from rat or guinea pig skin, rabbits form high titer, species-specific antibodies to collagen. Antibody is directed primarily against the alpha2 chain of collagen with little reaction with the alpha1 chain. The amino terminal peptide of cyanogen bromide cleavage of the alpha2 chain o…
Contribution to the study of mechanism of stabilizing action of esters of phosphorous acid
Abstract The rate of the reaction of a series of phosphites with cyclohexene hydroperoxide and cyclohexene peroxy radicals was studied. The results of the measurements were compared with the stabilization efficiency of the same compounds in isotactic and in atactic polypropylene at 160°C and 120°C respectively and dur…
Optical Phonons in Sodium Chlorate
The frequencies of the optical phonons in NaCl${\mathrm{O}}_{3}$ have been located by measuring the infrared reflectivity and the Raman scattering spectra. By using the Lyddane-Sachs-Teller relationship, a value of 5.6 was found for the static dielectric constant. Dielectric transition strengths were determined from t…