Materials Literature
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The variance in the sedimentation speed for a homogeneous suspension of solid spheres in a Stokes fluid is calculated for a particular choice of the distribution function of the spheres. In the infinite particle number limit, the variance is found to be infinite.
The polyaniline (PANI) is an interesting material because it can be a very stable electronic conductive polymer. It shows several electrochemical redox systems which have to be elucidated. For the application as battery material, it is the polymer probably which has the larger charge density (Ah/kg).
This paper reports on the effect of additives on the properties of injection moulded composites based on polypropylene (PP) and high density polyethylene (HDPE) filled with wood and cellulose flour. Three types of additives were studied: dispersion aids, elastomeric additives, and adhesion promoting agents. Some of th…
The fiftieth foundation anniversary of the Building and Cement Institute (Instituto de la Construcción y del Cemento "Eduardo Torroja ") has been celebrated. On this occasion, an exhibition of Eduardo Torroja’s works has been opened with the collaboration of the Civil Engineers College. At the same time, Scientific an…
Some materials usually employed in building edification have been analyzed for their radioactive contents. The specific activities of all the gamma rays emisors present in fourteen differents samples have been determined. In all the cases, only low activities (under 2 Bq/g) have been found for these samples collected…
A description is given of the properties of lead sheet for roofing and cladding purposes. Basic rules as far as installations are concerned are given, specially with respect to dimensions of the pieces, characteristics of Joints and fixings, and watertightness conditions. Compatibility of lead with other building mate…
Limits fixed in Codes for the chemical characteristics of cements have been established with semi-empirical methods, given the complexity of influencing phenomena, without correspondence between these values and the physico-chemical or mechanical properties as durability or strength. Knowledge of statistical distribut…
In Colombian ways and means, since the application of no traditional constructive systems is growing up, and having recourse to the new Seismic Construction Code, it is necessary to work with cement mortars of defined and reproducible characteristics. An analysis of the variability affecting the mortars behaviour was…
A close relationship was found between the pH of soil suspensions in the SMP buffer solution (pHsmp) and the potential acidity of soils (H + Al) extracted by a neutral calcium acetate solution (r = 0.98), for twenty six soil samples of the State of Sao Paulo, Brazil, This relationship was represented by the equation l…
The equations of acoustoelasticity are formulated in both natural and initial frames of reference and applied to investigate the propagation of ultrasonic waves in orthotropic elastic solids with initial stresses. The foundation of the equations is re-examined for the purpose of applying them to the measurement of res…
A system which shows a relatively large blue-phase range is investigated. Owing to the small value of the cholesteric pitch the blue-phase shows no Bragg-reflections in visible light. Nevertheless, electric-field induced birefringence shows quite large values. The response times are a few tens of microseconds below 10…
Abstract When natural rubber is epoxidized under carefully controlled conditions, it can be converted to a totally new polymer with some properties more akin to speciality rubbers and some properties that appear to be advantageous for tire treads. Three levels of epoxidation have been extensively evaluated. They were…
The quinoid-benzenoid-diimine form, (=(C6H4)=N-(C6H4)-N=)x of “polyaniline” shows excellent cathode characteristics including recyclability when used in conjunction with a zinc anode in an aqueous electrolyte of (l. 0M ZnCl2 + 0. 5M NH4Cl) having a pH of ∼ 4. The reduced form of this material, (-(C6H4)-N(H)-(C6H4)-N(H…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTExcited-state properties of a triply ortho-metalated iridium(III) complexK. A. King, P. J. Spellane, and Richard J. WattsCite this: J. Am. Chem. Soc. 1985, 107, 5, 1431–1432Publication Date (Print):March 1, 1985Publication History Published online1 May 2002Published inissue…
“Polyaniline” has been synthesized in various forms both chemically and electrochemically in aqueous media. The qulnoid-benzenoid-diimine form, an insulator, is doped by dilute aqueous protonic acids to the metallic regime ([sgrave] = 5 ohm−1cm−1; compressed pellet) to give the corresponding iminium salt. This represe…
ABSTRACT: Effective interresidue contact energies for proteins in solution are estimated from the numbers of residue-residue contacts observed in crystal structures of globular proteins by means of the quasi-chemical approximation with an approximate treatment of the effects of chain connectivity. Employing a lattice…
Starting from the dielectric function of a two-band model, a generalised Horie formula (1959) for the wavevector-dependent frequency omega p (q), of the valence plasmon is derived. The dispersion is determined by band-structure effects and the q-dependence of the oscillator strength. The latter is calculated using kp…
For part II, see ibid., vol.17, p.4725 (1984). Measurements of the inelastic neutron scattering spectrum of molten MgCl 2 show directly the existence of a weak soft mode in the momentum transfer range 1.5<Q<1.8 AA -1 . Such modes are not directly observed in molten CaCl 2 and have not been seen in other molten salts.…
Resistivity and X-ray diffraction measurements have been made for the quasi-one-dimensional conductors (MSe 4 ) 2 I (M=Ta and Nb). (TaSe 4 ) 2 I is known to undergo a phase transition at T c approximately=260K. A phase transition of (NbSe 4 ) 2 I was found to take place at T c approximately=210K. Non-linear conduction…