The Impact of Compressible Liquids
Consideration is given to liquid impact in the supersonic regime in order to characterize pressure loading and other mechanisms which could damage a solid target such as a jet in flight. The liquid ...
Materials Literature
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Dry Etch Resistance of Organic Materials
The dry etch resistance of metal‐free organic materials, mainly resist materials, has been studied. Etch rates have been measured under argon ion‐beam, oxygen ion‐beam, and oxygen plasma etching conditions. It is found that the etch rate under ion bombardment has a linear dependence on the of the etched materials, whe…
Chloramphenicol Acetyltransferase: Enzymology and Molecular Biology
Naturally occurring chloramphenicol resistance in bacteria is normally due to the presence of the antibiotic inactivating enzyme chloramphenicol acetyltransferase (CAT) which catalyzes the acetyl-S-CoA-dependent acetylation of chloramphenicol at the 3-hydroxyl group. The product 3-acetoxy chloramphenicol does not bind…
Wave Propagation in the Split Hopkinson Pressure Bar
Elastic wave propagation in the split Hopkinson pressure bar (SHPB) is discussed with an emphasis on the origin and nature of the oscillations that often trail the leading edge of the pressure wave. We show that in the conditions of the SHPB test the pressure bars vibrate in the fundamental mode and that elastic wave…
Evaluation of Collagen Crosslinking Techniques
The properties of collagen films crosslinked by physical and chemical techniques were compared to the properties of films crosslinked with glutaraldehyde (GTA). Physical techniques studied include exposure to short wave (254 nm) u.v. irradiation and severe dehydration. Chemical techniques studied include immersion of…
The optical properties of thallium-like impurities in alkali-halide crystals
Per me si va nella citt`a dolente Per me si va nell'eterno dolore Per me si va tra la perduta gente Dante, Inferno, III, 1–3 Experimental and theoretical investigations of optical absorption and emission spectra of alkali-halides doped with Tl+-like impurities are reviewed. The Jahn—Teller effect plays an important ro…
Energetics and formation kinetics of helium bubbles in metals
Recent theoretical work on the energetics and formation kinetics of helium bubbles in metals is reviewed. The energetics are discussed in particular for bubbles with radii between 10 and 1000 Å containing helium under very high pressures (nonideal gas bubbles). For this size range, the bubble formation free energy is…
Colloidal crystals
The so-called colloidal crystals are monodisperse colloids in which colloidal particles organize themselves in long-range-ordered crystals. First, the monodispersity of colloidal particles and their interactions, essential for crystallization phenomenon, are discussed and illustrated using examples of natural and synt…
Structural destabilization induced by lithium intercalation in MoS2 and related compounds
2H-MoS 2 is a semiconductor with a hexagonal layered structure. Each Mo atom is prismatically coordinated by six S atoms. Our in situ X-ray diffraction results indicate that, upon intercalation, the MoS 2 host lattice undergoes a first order phase transition in which the Mo coordination changes from trigonal prismatic…
Studies on the Relationship Between Water‐satured State and Crystallinity by the Diffraction Method for Moistened Potato Starch
Abstract Crystallinity was measured by X‐ray diffraction method and water‐saturated state was determined by means of the moisture contents calculated from the crystallinity for moistened cellulose and potato starch. In the X‐ray diffractograms the upper areas which were separated by the straight line joined the points…
Microfibrillated cellulose, a new cellulose product: properties, uses, and commercial potential
A new form of cellulose, which is expanded to a smooth gel when dispersed in polar liquids, is produced by a unique, rapid, physical treatment of wood cellulose pulps. A 2% suspension of microfibrillated cellulose (MFC) in water has thixotropic viscosity properties and is a stable gel on storage, or when subjected to…
Vibrational investigations of polyoxometalates. 2. Evidence for anion-anion interactions in molybdenum(VI) and tungsten(VI) compounds related to the Keggin structure
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTVibrational investigations of polyoxometalates. 2. Evidence for anion-anion interactions in molybdenum(VI) and tungsten(VI) compounds related to the Keggin structureClaude Rocchiccioli-Deltcheff, Michel Fournier, Raymonde Franck, and Rene ThouvenotCite this: Inorg. Chem. 198…
An empirical method for correcting diffractometer data for absorption effects
Absorption effects usually present the most serious source of systematic error in the determination of structure factors from single-crystal X-ray diffraction measurements if the crystal is not ground to a sphere or cylinder. A novel method is proposed for the correction of these effects for data collected on a diffra…
Shake-up processes accompanying electron transitions in atoms
Elementary processes in many-electron atoms—radiative and Auger transitions, photoionization, ionization by electron impact, etc.—are usually accompanied by relaxation of the electron shells. The conditions under which such an inherently many-electron problem can be solved in the shake-up approximation are examined, a…
Characterization of Metamorphism through Mineral Equilibria
Volume 10 of Reviews in Mineralogy reviews the use of a powerful probe into metamorphic process: mineral assemblages and the composition of minerals. Put very simply, this volume attempts to answer the question: "What can we learn about metamorphism through the study of minerals in metamorphic rocks?" It is not an enc…
On the parametrisation of semi-empirical methods for ionic crystals
Several INDO calculations of the electronic structure of pure LiF crystal were performed in order to investigate the dependence of predicted crystalline properties upon the parameters used in the method. A new parametrisation scheme is proposed for ionic crystals.
Orientation dependence of the23Na nuclear quadrupole spin-lattice relaxation in sodium nitrite
The orientation dependence of W 2 /W 1 for 23 Na in NaNO 2 has been measured at room temperature by a CW double-resonance method. With the exception of one point, the data are in very good agreement with the general theoretical orientation dependence. The following ratios of the M-tensor components are given by the th…
Vibrational spectra and phase transitions in ferroelectric-ferroelastic langbeinites: K2Mn2(SO4)3, (NH4)2Cd2(SO4)3and Tl2Cd2(SO4)3
Complete vibrational spectra (Raman, infrared and far-infrared) have been recorded for the ferroelastic, ferroelectric langbeinites, K 2 Mn 2 (SO 4 ) 3 , (NH 4 ) 2 Cd 2 (SO 4 ) 3 and Tl 2 Cd 2 (SO 4 ) 3 . From the polarised single-crystal Raman spectra the vibrational modes, corresponding to the 'internal' vibrations…
Tests of Universality of Percolation Exponents for a Three-Dimensional Continuum System of Interacting Waterlike Particles
Molecular-dynamics calculations for interacting waterlike particles are used to estimate values of percolation exponents. Results are consistent with accepted values for ordinary random-bond percolation for a three-dimensional lattice. Study of a correlated-site percolation problem, defined by the connectivity of thos…
Some theoretical and structural aspects of gold cluster chemistry
Abstract The bonding in tertiary phosphine cluster compounds of gold is sufficiently straightforward to permit an effective interaction between theoretical concepts developed from semi-empirical molecular orbital calculations and synthetic and structural chemistry. At the simplest conceptual level the isolobal nature…