Materials Literature
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A new method is described which produces fully dense, well-aligned Nd-Fe-B magnets from rapidly quenched ribbons. Full density is achieved by hot pressing at ∼15 kpsi in argon at 700 °C. A second hot press in a larger die cavity to allow deformation transverse to the press direction (die upsetting) introduces a prefer…
Time-of-flight drift mobility experiments have been carried out on pure and chlorine-doped amorphous selenium films. The temperature and field dependence of the drift mobility of both types of carriers have been investigated and the charge transport mechanism has been critically examined in terms of various shallow-tr…
Time-of-flight drift mobility experiments have been carried out on evaporated films of amorphous (a-)Se 0.995 As 0.005 with chlorine as an additive up to approximately 70 at.ppm; drift mobility has been measured as a function of temperature at various applied fields. It is shown that shallow hole traps at approximatel…
ABSTRACT The deposition of scale in the near-wellbore formation and production string can result in a significant decrease in well capacity. Correctly designed scale inhibitor squeezes can successfully prevent scale deposition and the corresponding productivity declines. However, inadequate knowledge of the chemistry…
ABSTRACT The objectives of the study reported in this paper were to evaluate the thermal stability of commercially available surfactants at typical steam injection temperatures and to investigate the kinetics of the thermal degradation process. Surfactant stability tests were performed under conditions of high tempera…
Abstract Electron energy-loss spectroscopy (e. e. l. s.) performed with an electron microscope can be used to obtain plasmon spectra, near-edge fine structure and extended electron energy-loss fine structure (ex. e. l. f. s.), as well as to do chemical analysis on truly microscopic samples. However, the very strength…
Abstract A number of mineralogical and synthetic precipitates undergo solid to solid phase changes via a solution phase. A review of the literature reveals a lack of both experimental data and a framework for its interpretation. A model is developed, for the case of a polymorphic phase transformation, which involves t…
A simple natural Landau theory of two- or three-component systems is described, which appears to give a region of the phase diagram in which quasicrystalline ordering is the state of lowest free energy. The quasicrystals are stabilized by special geometric relations between the length scales characterizing the compone…
Theories for elasticity and dislocation defects in two-dimensional pentagonal and three-dimensional icosahedral quasicrystals are presented.Received 4 February 1985DOI:https://doi.org/10.1103/PhysRevLett.54.1520©1985 American Physical Society
The crystal structure with icosahedral point-group symmetry and long-range orientational order observed by Shechtman et al. in Mn-Al alloys can be explained as a multiple-q density-wave structure with only one length scale. Its existence and stability can be understood from a simple Landau theory. The diffraction spot…
Influence de la composition du caoutchouc, des systemes vulcanisants, de la teneur en oxyde de zinc, du polyethylene chlorosulfone, des antioxygenes, des coagents
Abstract A method is proposed for solving the problem of temperature optimal control in tubular fixed‐bed reactors with reaction systems described by Langmuir‐Hinshelwood‐Hougen‐Watson kinetic equations. The optimization problem is formulated by N state differential equations corresponding to the N differential fixed‐…
Abstract Polarization measurements of two‐phonon absorption spectra in TISe and TlInSe 2 , and of the second‐order Raman scattering spectrum in TISe are carried out in the range of overtone and combination frequencies at room temperature. The observed peaks in the absorption and scattering spectra are interpreted by t…
Radon-222, a naturally occurring radioactive noble gas, is often a contaminant in natural gas. During fractionation at processing plants, Radon tends to be concentrated in the Liquified Petroleum Gas (LPG) product stream. Radon-222 decays into a number of radioactive metallic daughters which can plate out on the inter…
Abstract Poly[1‐(2‐oxazoline‐2‐yl)ethylene] ( 2a ), poly[1‐(5‐methyl‐2‐oxazoline‐2‐yl)ethylene] ( 2b ), poly[1‐(4,4‐dimethyl‐2‐oxazoline‐2‐yl)ethylene] ( 2c ), poly[1‐(4,4‐dimethyl‐5,6‐dihydro‐4 H ‐1,3‐oxazine‐2‐yl)ethylene] ( 2d ), and poly[1‐(4,4,6‐trimethyl‐5,6‐dihydro‐4 H ‐1,3‐oxazine‐2‐yl)ethylene] ( 2e ) were sy…
A description is given of detailed analyses of neutron powder diffraction data on Nd2Fe14B at several temperatures, and relationships between the crystal structure and the magnetic properties via comparison with other rare earth-transition metal systems, Nd2Fe17 in particular, are discussed. Diffraction studies have a…
Synopsis Substantivity of various (125)I-labelled collagen hydrolysates to virgin or bleached and dyed European hair or human callus was tested under conditions which simulated actual application of such hydrolysates in shampoos or foam baths. Factors which most strongly influence protein substantivity were identified…
The influence of acidity on the thermochemical stability of molten sodium nitrate‐nitrite mixtures used as heat‐transfer fluids (as in the case of the French electrosolar power system called Thémis) has been demonstrated by considering the diagram relative to redox systems corresponding to these mixtures and been esta…
The method for determining of optical constants of weakly absorbing plane-parallel films from the fringe pattern of the transmittance spectra is extended. The model supposes that the film thickness varies slowly but that the surface of the film is smooth, so that scattering of the beam can be neglected. A simple appro…
The systematics of [001] twist boundary structure is presented formally in terms of a structural unit/grain boundary dislocation hierarchical model and the earlier model of Sutton is generalized. By comparison with experimental observation and atomistic calculation using pair-potential models the physical significance…