Moldes de aluminio para las probetas cúbicas de hormigón
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Materials Literature
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Bloques Wilson
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Importancia del momento en que se realiza el curado del hormigón
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Lattice energy of ionic crystals
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Oxidation of Alloys Involving Noble Metals
Diffusion processes during the oxidation of alloys involving noble metals are analyzed theoretically. An oxide film of uniform thickness is stable only if diffusion in the alloy is relatively rapid compared with diffusion in the oxide of the less noble metal. Otherwise, there is the tendency to form a rugged alloy‐oxi…
Dynamic Method for Measuring the Pyroelectric Effect with Special Reference to Barium Titanate
A dynamic method has been developed for the study of the pyroelectric effect. Transient currents produced in single crystals of barium titanate when subjected to flashes of light are shown to be pyroelectric in origin. The illumination results in a small change in the temperature of the crystal which, in turn, causes…
Dielectric Behavior and Structure
Abstract not Available.
III. Dislocation densities in some annealed and cold-worked metals from measurements on the X-ray debye-scherrer spectrum
Two basic equations are derived for deducing the dislocation density in powdered materials from the particle size and strain breadth measured from the Debye-Schemer spectrum. In the particle size estimate, it is assumed that the material has a block structure similar to that found in microbeam studies and that the dis…
Field Emission Microscopy of an Allotropic Transformation:α−βTitanium
The field emission microscope has been applied to a study of the allotropic transformation in single microcrystals of titanium. Patterns with symmetry characteristic of the high and low temperature phases are presented. Techniques for analyzing the patterns are outlined. Data derived from the pattern analyses give an…
Ferromagnetic Resonance in Manganese Ferrite Single Crystals
The microwave properties of two types of manganese ferrite single crystals have been investigated by means of the ferromagnetic resonance phenomenon from 300\ifmmode^\circ\else\textdegree\fi{}K to 4.2\ifmmode^\circ\else\textdegree\fi{}K and at 24 000, 9100, 5600, and 2800 Mc/sec. The low resistivity of one of the crys…
Interpretation of the Optical Properties of Metal Surfaces
The surface optical properties of the metals Ag, Au, Cu, Pt, Ir, and Ni in the infrared are shown to obey a simple generalized form of the Drude formula for the free electron theory, but involving two types of free electrons. If the surface optical constants are not anomalous, this procedure may be interpreted as a so…
Hall Effect and Conductivity of InSb
Hall coefficient and conductivity of single-crystal InSb have been measured from 1.3\ifmmode^\circ\else\textdegree\fi{}K to 700\ifmmode^\circ\else\textdegree\fi{}K. Impurity band conduction and an acceptor ionization energy of 7\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}3}$ ev have been observed in $p$-typ…
Instability in the Motion of Ferromagnets at High Microwave Power Levels
Received 22 September 1955DOI:https://doi.org/10.1103/PhysRev.100.1788©1955 American Physical Society
Effects of temperature on the plastic properties of aluminium crystals
Abstract By changing the temperature of deformation, during tensile experiments on single crystals of aluminium , it has proved possible to separate reversible changes of flow stress with temperature from irreversible ones. Below 130° K the reversible change of flow stress is large; above room temperature it is hardly…
X-Ray Attenuation in Lead, Aluminum, and Concrete in the Range 275 to 525 Kilovolts
A great deal of work has been done in recent years to determine how the attenuation of an x-ray beam is modified by the contribution of radiation scattered in the absorber. This scattering contribution depends on the irradiated area and on the solid angle subtended by the detector at the absorbers. The limiting case o…
The Effect of Water and of Glycerol on the Decarboxylation of Oxalic Acid
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Effect of Water and of Glycerol on the Decarboxylation of Oxalic AcidLouis Watts ClarkCite this: J. Am. Chem. Soc. 1955, 77, 23, 6191–6192Publication Date (Print):December 1, 1955Publication History Published online1 May 2002Published inissue 1 December 1955https://pubs.…
Developmental modification of fleece structure by adverse maternal nutrition
As part of a series of investigations on the factors influencing the development of the secondary follicle population during foetal and early post-natal life of lambs, the influence of severe restriction of the feed intake of ewes throughout pregnancy is recorded. Adverse maternal nutrition reduced the body weight and…
Observations on Certain Fluorescent Spots in Raw Cotton Associated with the Growth of Microorganisms
Evidence is presented which indicates that certain fluorescent spots observed in raw cotton under ultraviolet light are associated with the prior growth of microorganisms on the fiber. A striking and characteristic type of spot which fluoresces bright greenish- yellow was noted frequently in classers' samples from the…
Thermodynamic Properties of Alkali Metal Fluoborates and the Fluoborate Ion
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThermodynamic Properties of Alkali Metal Fluoborates and the Fluoborate IonAubrey P. AltshullerCite this: J. Am. Chem. Soc. 1955, 77, 23, 6187–6188Publication Date (Print):December 1, 1955Publication History Published online1 May 2002Published inissue 1 December 1955https://…
Zur Kenntnis der Ferrate(VI)
Abstract Die Darstellung von reinem K 2 FeO 4 , Cs 2 FeO 4 , BaFeO 4 · aq und SrFeO 4 · aq wird beschrieben. Die thermische Zersetzung von K 2 FeO 4 im O 2 ‐Strom wird untersucht; sie führt höchstwahrscheinlich zur gleichzeitigen Bildung von K 3 FeO 4 und KFeO 2 . K 2 FeO 4 reagiert mit der berechneten Menge Na 2 O un…