Materials Literature
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Recently new smectic phases have been discovered: the SmF and Sml phases. They appear in some coumpounds when the length of the aliphatic chains reaches a sufficient value to minimize the interlayer coupling. They are characteristic of new stages between the three-dimensionaly (3D) ordered SmB and SmG and the “2D liqu…
In order to model fluid capillarity effects, the Dutch physicist Korteweg formulated in 1901 a constitutive equation for the Cauchy stress that included density gradients. Specifically, Koretweg proposed for study a compressible fluid model in which the "elastic" or "equilibrium" portion of the Cauchy stress tensor T…
Molecules that are photostable in the solid state can be rendered photoactive if, by burial within crystals of closely analogous monomers, they can be made to mimic the molecular conformation of the latter; this fact is demonstrated for a pair of cyclopentanone derivatives, and the general significance of this result…
Abstract Four acid montmorillonitic soil profiles were sampled to study thermodynamic‐stability relationships and chemical weathering of soil minerals. Solid‐ and solution‐phase characterization indicated smectite to be the metastable precursor of kaolinite with the highest rate of transformation occurring in topsoil…
ABSTRACT Clay mineral transformations of 10 North Sea wells have been studied, and several transformation stages picked out and correlated with geothermal variations: smectite disappears at 149 to 167°F (65 to 75°C), whereas transformations in the mixed-layer illite-smectite clay minerals are observed between 113 and…
A pin-on-disk tribometer was used to study the coefficient of friction as a function of temperature for tricresylphosphate (TCP) on CVM M-50 tool steel under the following conditions: TCP was present in a liquid reservoir (bulk lubrication), and TCP was applied as a liquid layer directly to the disk (limited lubricati…
Precipitation of 6 phase in an Fe-25Cr-7Ni-3Mo alloy with α/γ duplex structure has been studied systematically and the following results were obtained:(1) TTP diagram for the a phase precipitation was a C-type with a nose at 820°C.(2) σ phase nucleated on the α/γ interfaces and grew into α grains as a eutectoid reacti…
Manufacture of ceramics microstructure of ceramics mechanisms of corrosion experimental methods resistance of ceramics thermodynamic calculations properties and applications of different types of ceramics choosing a ceramic for a corrosive environment.
Abstract Structural phase transitions in the LaMnO 3+λ system are studied at various temperatures and with different Mn 4+ ion concentrations. Two structural phase transitions are established. The O′‐orthorhombic – O‐orthorhombic transition (O′O transition) is due to removing the cooperative Jahn‐Teller distortions a…
Titanium and its alloys have been commercially available for over three decades. Its high strength-to-weight ratio plus its resistance to corrosion were recognized early and utilized by the aerospace and chemical industries, as well as by the medical profession. The benefits of corrosion resistance, biocompatibility,…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMoessbauer spectra of oxidized iron porphyrinsDaniel R. English, David N. Hendrickson, and Kenneth S. SuslickCite this: Inorg. Chem. 1983, 22, 2, 367–368Publication Date (Print):January 1, 1983Publication History Published online1 May 2002Published inissue 1 January 1983http…
The silica in some biominerals has been investigated by electron microscopy and i.r. and n.m.r. spectroscopy and has been shown to be amorphous and to contain many Si–OH units.
Abstract A new single‐crystal scintillator intended for applications in a scanning electron microscope (SEM) is presented. It is a single‐crystal disc of yttrium aluminium perovskite activated by trivalent cerium free of traces of Fe ions. The single crystals of YAlO 3 : Ce 3+ (YAP: Ce 3+ ) were prepared by the Czochr…
Abstract The consistency of fats can be measured with the cone penetrometer (AOCS Method Cc 16‐60). Several suggestions have been made to convert readings of penetration depth into parameters such as yield value, hardness or hardness index. This may extend the usefulness of the method. Motor‐driven penetrating devices…
The energy shift of the He 11S0−21P1 transition, ΔE(n), can be used to determine the density, n, of He in bubbles in metals. A self-consistent band structure calculation for solid fcc He yields a linear relationship ΔE=C.n with C th=22 × 10−3 eV nm3. Systematic electron energy loss spectroscopy and transmission electr…
Normal arteries have properties which match the low output impedance of the heart to the high peripheral impedance. These properties can be assessed in terms of compliance (% diameter change per unit pressure change) as well as by other haemodynamic parameters. Experiments were designed using vein, Dacron and expanded…
Measurements are presented in this paper of the pulsation amplitude of an individual air bubble that is levitated in a glycerine–water mixture by a stationary acoustic wave operating at a frequency of 22.2 kHz. Observations of the bubble pulsation for a wide range of bubble sizes demonstrate the existence of the n=2 h…
Eight new cardenolide glycosides, 19-deoxyuscharin (1b), 4′β-hydroxygomphoside (1k), 3′-didehydrogomphoside (1d), 3′-epigomphoside (1e), 3′-epiafroside (2e), 3′-epigomphoside 3′-acetate (1f), 3′-didehydroafroside (2d), and 3′-epiafroside 3′-acetate (2f), have been isolated from Asclepias fruticosa R. Br. The structure…
Abstract
The synthesis of tetra-arylporphyrins, for studies in solar energy conversion, is described. They are derived from 5,10,15,20-meso-tetrakis(4-hydroxyphenyl)porphyrin (4) which, in basic media, forms a green intermediate that is probably the tetraphenoxide (6). The porphyrins (10) and (13), were synthesised as prospect…