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The flow of powders and of liquids of high viscosity

It is argued that powders have so many particles per unit volume that they can be treated in a manner similar to conventional liquids. They have an entropy S(V,N), but as energy is not important the place of temperature delta E/ delta S is taken by delta V/ delta S. Equations capable of giving plug flow are derived. I…

Influence of hydrogen-consuming bacteria on cellulose degradation by anaerobic fungi

The presence of methanogens Methanobacterium arboriphilus, Methanobacterium bryantii, or Methanobrevibacter smithii increased the level of cellulose fermentation by 5 to 10% in cultures of several genera of anaerobic fungi. When Neocallimastix sp. strain L2 was grown in coculture with methanogens the rate of cellulose…

Pitting Corrosion of Al and Al‐Cu Single Crystals

Pitting of single crystals of Al and homogenized Al‐Cu alloys has been studied on low index surfaces as a function of surface orientation and alloy content in . The potentials at which pitting phenomena occurred were determined potentiodynamically using single‐cycle pitting tests at a scan rate of 0.5 mV/s. Galvanosta…

Radiofrequency plasma deposition of oxygen‐containing films on polystyrene and poly(ethylene terephthalate) substrates improves endothelial cell growth

Polystyrene and poly(ethylene terephthalate) substrates were modified by radiofrequency plasma deposition with organic vapors comprised of carbon, oxygen, and hydrogen (acetone, methanol, glutaraldehyde, formic acid, allyl alcohol, and ethylene oxide). The treatments resulted in the deposition of a film at least 100 A…

The structure of sodium silicate glass

Atomistic scale computer simulations can provide a more detailed understanding of the structure of glasses. Our results on sodium silicate glasses show that sodium ions are associated with nonbridging oxygens and that the sodium ions and nonbridging oxygens tend to aggregate to form silica rich regions and alkali rich…

A surface-electrochemical basis for the direct logarithmic growth law for initial stages of extension of anodic oxide films formed at noble metals

Measurements on anodic surface oxidation of noble metals as a function of time and electrode potential show that the initial extension and subsequent thickening of such oxide films is directly logarithmic in time. A striking feature of this behavior is that the direct logarithmic extension law already applies to incre…

Scanning electron microscopy of vascular corrosion casts--technique and applications: updated review.

The present paper states very briefly the main steps leading to the technique of scanning electron microscopy (SEM) of vascular corrosion casts. From the terms presently used (injection method, microcorrosion cast, injection replica, vascular corrosion cast, vascular cast) the use of "vascular corrosion cast" for lymp…

Anticipations of the Geometric Phase

In science we like to emphasize the novelty and originality of our ideas. This is harmless enough, provided it does not blind us to the fact that concepts rarely arise out of nowhere. There is always a historical context, in which isolated precursors of the idea have already appeared. What we call “discovery” sometime…

Array-type universal profile function for powder pattern fitting

An array-type universal profile function for powder-pattern fitting is described. It is defined as an array of unknown parameters representing the profile heights at discrete angular steps. The unknown parameters are determined during least-squares fitting together with the integrated intensity, the peak position, the…

Far-infrared spectroscopic investigations on CuO

Far-infrared reflection spectra of a polycrystalline sample of monoclinic CuO were measured in the frequency range from 30 to 700 ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ at temperatures between 10 and 300 K. The six observed lattice vibrational modes at 147, 161, 321, 478, 533, and 587 ${\mathrm{cm}}^{\mathrm{\ensu…

High Temperature Corrosion of Engineering Alloys

This extensive materials selection and application book is the first of its kind. It describes a comprehensive treatment of all forms of high temperature corrosion problems encountered in industry, especially gas turbine and aerospace, heat treating, mineral and metallurgical processing, ceramic, electronic and glass…

Fatigue and switching in ferroelectric memories: Theory and experiment

A theoretical model of fatigue in ferroelectric thin-film memories based upon impact ionization (e.g., Ti+4 to Ti+3 conversion in PbZr1−xTixO3), resulting in dendritic growth of oxygen-deficient filaments, is presented. The predictions of spontaneous polarization versus switching cycles Ps(N) are compared with both Mo…

Anion-exchange reactions of layered double hydroxides

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAnion-exchange reactions of layered double hydroxidesMartina Meyn, Klaus Beneke, and Gerhard LagalyCite this: Inorg. Chem. 1990, 29, 26, 5201–5207Publication Date (Print):December 1, 1990Publication History Published online1 May 2002Published inissue 1 December 1990https://p…

Structure of a ferroelectric and ferroelastic monodomain crystal of the perovskite BiFeO3

A ferroelec. and ferroelastic monodomain single crystal of BiFeO3 at space group R3c is rhombohedral, with a 5.57874(16), c 13.8688(3) .ANG.; arh 5.6343 .ANG., arh 59.348 Deg; d. (calcd.) = 8.337 for Z = 6. Final R = 2.4, Rw = 1.9% for 422 reflections. The structure can be described as a rhombohedrally distorted simpl…

Occurrence, metabolism, metabolic role, and industrial uses of bacterial polyhydroxyalkanoates

Polyhydroxyalkanoates (PHAs), of which polyhydroxybutyrate (PHB) is the most abundant, are bacterial carbon and energy reserve materials of widespread occurrence. They are composed of 3-hydroxyacid monomer units and exist as a small number of cytoplasmic granules per cell. The properties of the C4 homopolymer PHB as a…

Structure of the Reduced TiO 2 (110) Surface Determined by Scanning Tunneling Microscopy

The scanning tunneling microscope has been used to image a reduced TiO(2)(110) surface in ultrahigh vacuum. Structural units with periodicities rangng from 21 to 3.4 angstroms have been clearly imaged, demonstrating that atomic resolution imaging of an ionic, wide band gap (3.2 electron volts) semiconductor is possibl…

57Fe-Bearing Oxide, Silicate, and Aluminosilicate Minerals

Correlations have been sought between Mossbauer spectral parameters and several crystal structure properties of Mg-Al oxide and silicate minerals hosting iron cations as minor constituents. Plots of isomer shift (I.S.) versus various bond length-related parameters, including mean metal-oxygen distance (R) of a coordin…

Structure of Phototrophic Prokaryotes

INTRODUCTION to the PHOTOTROPHIC BACTERIA and the USE of ELECTRON MICROSCOPY in THEIR STUDY. INTRODUCTION. PHOTOTROPIC PROKARYOTES. Introduction. Oxygenic Phototrophs. Cyanobacteria. Chloroxybacteria. Anoxygenic Phototrophs. Purple Phototrophs. Green Phototrophs. Heliobacteria. ELECTRON MICROSCOPY. Introduction. Scann…

Brittle-ductile transition in intrinsic fracture behavior of crystals

A transition of brittle to ductile propagation of a sharp crack in a crystal is observed by molecular-dynamics simulation and the transition mechanism shown to be the emission of dislocations at the crack tip and activation of specific slip systems appropriate to the crystal structure. Implications for extension of cu…