Materials Literature
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Angle-resolved photoemission is shown to be a very versatile technique which probes electronic structure as well as geometric structure. All quantum numbers of an electronic state can be determined. In particular, energy and momentum of electrons in a solid are probed by measuring energy and momentum of photoelectrons…
Chemically prepared polypyrrole was treated with diphenyliodonium hexafluoroarsenate and upon u.v. irradiation a conductivity of 3 × 10–3Ω–1 cm–1 was attained.
Helium bubble formation was observed in austenitic stainless steels by transmission electron microscopy following implantation of 30 to 1000 appm helium at room temperature and annealing at 700 to 800°C. Helium bubble distributions at dislocations and at various grain boundaries and precipitates were studied. It was f…
Previous theoretical treatments of the scattering of conduction electrons at surfaces are reviewed and it is found that a more complete theory is necessary if the effects of surface scattering in transport phenomena are to be adequately understood. The boundary condition for the distribution function is derived and an…
Microscopical, miscibility and X-ray studies establish the existence of two new mesophases in the two enantiomers of 1 (methyl)-heptyl terephthalidene bis amino cinnamate. In one of this two mesophases the two enantiomers do not exhibit a total miscibility range; while for the second the untwisted form observed with t…
Exact calculations using transfer matrices on finite strips are performed to study the two-dimensional problem of one lattice animal with an attractive nearest neighbour interaction. Thermodynamic quantities such as specific heat, compressibility, thermal expansion are calculated. Finite size scaling with two strips o…
Les propriétés magnétiques statiques d'une chaîne isotrope formée en un ordre alterné de spins quantiques 1/2 et de spins classiques sont déterminées analytiquement en toute rigueur. La susceptibilité théorique est un bon accord avec les mesures de Verdaguer sur le composé CuMn(S2C2O 2)2(H2O)7,5.
A critical review is presented of published data on hydrogen, hydrides, and delayed hydrogen cracking (or hydrogen-induced delayed cracking, HIDC) in zirconium and its alloys. It is shown that factors such as solution temperature, cooling rate, and applied or residual stresses greatly affect the hydride morphology and…
Solutions are given for the spreading of a thin drop using lubrication theory. The relative importance of gravity to capillarity in the spreading is measured by the Bond number and all values of this number are covered. As usual when a moving contact line is present, a slip boundary condition is applied. For moderate…
Low-temperature reduction of LaNiO3 under hydrogen leads to new compounds such as La2Ni2O5 and LaNiO2 before total reduction. Hydrogen consumption, X-ray diffraction and XANES demonstrate the presence of these new phases. Ni3+ in LaNiO3 becomes Ni2+ in La2Ni2O5, and a pure monovalent nickel phase is obtained in LaNiO2…
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 ...
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…
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…
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…
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…
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…
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…
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…
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…
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…