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El problema de la determinación: del contenido de cemento en morteros; y hormigones fraguados
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…
Resistencia química del hormigón Estudio de dos cementos portland frente al agua de mar
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…
Influence of particle size ratio on the continuity of aggregates
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…
A theory of a.c. conduction in chalcogenide glasses
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…
Study of electron transport in As-Se-Te glasses
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…
ChemInform Abstract: IMIDAZOLATE COMPLEXES OF FERRIC PORPHYRINS
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…
Plasticity in a Smectic-ALiquid Crystal
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.…
Periodic grain boundary structures in aluminium I. A combined experimental and theoretical investigation of coincidence grain boundary structure in aluminium
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…
Dimerized Organic Linear-Chain Conductors and the Unambiguous Experimental Determination of Electron-Molecular-Vibration Coupling Constants
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
New rhenium containing seignettomagnets and ferroelectrics
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…
Inversion domains in γ-brass type phases. Stabilisation mechanism – the role of electron concentration
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-…
Mechanism of superplastic deformation in a magnesium alloy. I. Structural changes and operative deformation mechanisms
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…
Luminescence of CdCl2-CdBr2Solid Solutions
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…
High-pressure studies of luminescent spectra and lifetimes in alkali halides doped withCu+andAg+
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…
Infrared-active phonons inCr2O3
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…
Linear and nonlinear susceptibilities of rare earth ferroic molybdates
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…
Raman spectroscopy of the charge-density-wave state in1T- and2H−TaSe2
The Raman spectrum of $1T\ensuremath{-}\mathrm{T}\mathrm{a}{\mathrm{Se}}_{2}$ has been studied for $2<T<480$ K. Changes in the Raman spectra have been observed which are correlated with the 473-K phase transition from the commensurate charge-density-wave (CDW) state to the incommensurate CDW state. The temperatu…
Electronic surface and bulk transitions on clean ZnO surfaces studied by electron energy-loss spectroscopy
Clean cleaved ($1\overline{1}00$), (0001), and ($000\overline{1}$) surfaces of ZnO have been studied by electron energy-loss spectroscopy with primary energies ${E}_{0}$ between 35 and 100 eV. Differences between the nonpolar ($1\overline{1}00$) and the polar (0001) surfaces can be explained by the optical anisotropy…
The Nearly Commensurate Phase and Effect of Harmonics on the Successive Phase Transition in 1T-TaS2
The phase transitions of the charge density wave (CDW) state in 1T-TaS 2 are studied both theoretically and experimentally. The positions and intensities of the fundamental and third-order harmonic of the CDW are determined by X-ray diffraction. In order to understand the successive phase transitions, a theory is pres…