Materials Literature
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El acero embebido en el hormigón se encuentra sometido a un medio de elevada alcalinidad (pH comprendido entre 12 y 13), debido a la cal libre, a los álcalis que contiene el cemento, y al Ca(0H)2 que se forma durante la hidratación de los silicatos. En esta situación, el acero se halla recubierto por una capa de óxido…
El trabajo apunta la importancia que reviste el enfriador de clínker en el tema del ahorro de energía. Para un mejor conocimiento del funcionamiento de aquél se ha puesto a punto un modelo que permite predecir el efecto de cambios en la velocidad de parrilla, caudal de aire de enfriamiento, recirculación de gases cali…
Se trata en este trabajo de señalar el campo y las condiciones de aplicación del método NELC 5.01-a) para determinar la dosificación de cemento en morteros y hormigones fraguados, a la vista de los nuevos tipos de cemento del vigente y reciente Pliego de Prescripciones Técnicas Generales para la Recepción de Cementos…
El comportamiento de los morteros y hormigones sometidos a la acción del agua de mar ha sido objeto de numerosos trabajos como consecuencia de la gran cantidad de obras marítimas construidas a base de hormigón en masa y armado; de aquí, que sea un tema que ha preocupado y sigue interesando no sólo desde un punto de vi…
A model is developed which considers the volume fraction of dispersed phase necessary to form an infinitely long network as a function of the particle size ratio. Recognizing that neither a monolayer nor a double layer of dispersed particles around the primary phase is a necessary condition for continuity, the surface…
An electrical conductivity having a frequency dependence ∼ω s , where s < 1, has been reported for many amorphous semiconductors and chalcogenide glasses. It is the purpose of this paper to point out that the mechanism normally postulated for this behaviour, namely, thermally assisted quantum-mechanical tunnelling, is…
The low and high temperature DC and AC conductivities of As-Se-Te glasses have been studied with different Se:Te ratios. The transport behaviour has been discussed in terms of known transport mechanisms. The composition dependence of the conductivities are discussed in terms of known structures. The transport among ex…
Abstract Elektronenspektroskopische Untersuchungen zeigen, daß der aus dem Chloro‐tetraphenylporphinato‐Fe(III)‐Komplex (I) dargestellte Bis‐[imidazol]‐Komplex (II) durch verschiedene Basen wie Tetrabutylammoniumhydroxid,K‐tert.‐butoxid oder K‐imidazolat am Imidazol unter Bildung der Produkte (III) und (IV) deprotonie…
We present direct measurements of the layer rigidity in a smectic-$A$ liquid crystal, 4\ensuremath{'}-$n$-octyloxy-4-cyanobiphenyl. For low normal to the layers, the instantaneous induced stress is elastic and gives $B=0.8\ifmmode\times\else\texttimes\fi{}{10}^{7}$ cgs units at 60\ifmmode^\circ\else\textdegree\fi{}C.…
Abstract The results of a computer simulation of the structure of periodic grain boundaries between twin related crystals of aluminium are described. An interatomic potential derived on the basis of pseudo-potential theory was used. The algorithm employed allows simultaneous local atomic relaxation and rigid body tran…
We demonstrate that dimerized organic linear-chain conductors afford an unambiguous experimental determination of symmetry-allowed electron-molecular-vibration coupling constant.Received 25 July 1977DOI:https://doi.org/10.1103/PhysRevLett.39.1359©1977 American Physical Society
Complex investigations are made (neutron diffraction study, high temperature X-ray analysis, dielectric measurements at low and superhigh frequency ranges, resonance (ESR and Mössbauer effect) and magnetic measurements) on the known compounds A2BReO6 (A = Ba, Sr; B = Li, Mg, Ca, Mn, Fe, Co, Ni) and under high pressure…
The role of electron concentration in the formation and stabilisation of inversion anti-phase domain (IAPD) arrays in γ-brass type phases is determined by a study of γ-phases in the Ni-Zn, Co-Zn, and FeZn systems. IAPD arrays form in Ni-Zn alloys in the range Ni-75 at%Zn to Ni-80 at%Zn but are not observed in the Co-…
Structural changes and deformation processes acting during superplastic flow of a magnesium alloy (Mg + 1.5% Mn + 0.3% Ce, grain size Do ≈ 10 μm) in different regions of the σ-f(epsi;) curve are studied by a combination of techniques. It is experimentally established that the superplastic deformation of the alloy occu…
Studies of optical absorption and luminescence were carried out on CdCl 2 -CdBr 2 solid solutions in the whole concentration range. Three emission bands were observed in the regions of 2.1∼2.3 eV (Y-emission), of 2.4∼2.7 eV (G-emission) and of 3.2∼3.6 eV (UV-emission). When the concentration of CdBr 2 increases, the U…
The effect of pressure to 140 kbar has been measured on the room-temperature luminescent properties of some sodium and potassium halides doped with ${\mathrm{Cu}}^{+}$ and ${\mathrm{Ag}}^{+}$. The properties studied include peak location, peak half-width, and luminescent lifetime. A signal-averaging luminescent decay…
We have identified serious errors in a previously published assignment of the ir-active phonons for the $\ensuremath{\alpha}$-corundum structured crystal ${\mathrm{Cr}}_{2}$${\mathrm{O}}_{3}$. We have measured the ir-reflectance for the two principal polarizations, $\stackrel{\ensuremath{\rightarrow}}{\mathrm{E}}\ensu…
We have measured the linear and nonlinear susceptibilities of several mixed rare earth molybdates Ln2xGd2(1−x)(MoO4)3, where Ln is Nd, Sm, Gd, Tb, Ho, Yb. We conclude that the major part of the nonlinear optical properties is due to the MoO4 tetrahedra orientation and to the Mo–O bond hyperpolarizability. Extrapolated…