Materials Literature
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Liquid crystals may be classified in two major categories, namely, thermotropic and lyotropic. Thermotropic liquid crystals are commonly prepared by heating organic compounds, whereas lyotropic liquid crystals are made by mixing two or more components. Thermotropic liquid crystals are mainly of interest in this paper.…
A finite-element elastic analysis is made of a skull. Measurements were made of the geometry and thickness of a skull. The skull was then idealized with a doubly curved and arbitrary triangular shell element. Results suggest that the skull is well built for resistance to front loads. The importance of using a composit…
Single layers of nylon fabric have been subjected to high-speed missile impact at velocities ranging from 116 to 537 m/sec. The transient responses of the fabric and missile have been observed by high-speed photography. The photo graphs have shown that fabric deformation was pyramidal before penetration and more conic…
A recent investigation of the binary borosilicate glass system has led to the realization of a useful cladding material for pure fused silica core fiber optical waveguides. The feature which makes the borosilicate glass useful is that its index of refraction is sufficiently less than that of pure fused silica to allow…
The siphonophore Nanomia has a pair of giant fibres running along the stem, the larger of which conducts at velocities up to 3 metres/second. Histologically the two giant fibres appear to be composite, partially syncytial structures representing specializations within the general ectodermal nerve plexus.
Ceramic materials of interest for electronic components, such as ferroelectrics, ferrites, and transition metal oxides have no natural glass-forming habit. A rapid cooling of their melt is required to obtain homogeneous glasses. This is the most important requirement for controlling crystallization and phase dispersio…
Abstract Samples of ordinary “ash‐free” cellulose papers and similar samples decrystallized by swelling in liquid ammonia were pyrolyzed in vacuo to a weight loss ranging from <0.1% to nearly 20%. The samples were then nitrated and their molecular weight distributions determined by gel permeation chromatography. Wh…
The properties of two soil groups widely found in Java and Sumatra are studied. The two groups, closely related, are known pedologically as latosols and andosols, and are formed under tropical weathering conditions from volcanic parent material. The latosols are reddish in colour and are found at altitudes up to about…
Abstract The effects of crystallinity, orientation and degree of polymerization on the vacuum pyrolysis of cellulose have been investigated. Natural, modified and manmade celluloses were characterized and the kinetics of their pyrolysis at 251°C studied. The high‐temperature pyrolysis of these samples was also investi…
Inositol-independent (inos(+)) revertants of Neurospora induced in inositol-requiring mutants by treatment with wild-type DNA in previous studies were found to be stable and to grow well in the absence of inositol. Genetic data presented in this paper show that a major proportion of these induced revertants rarely tra…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStereochemistry of low-spin cobalt porphyrins. I. Structure and bonding in a nitrosylcobalt porphyrin and their bearing on one rational model for the oxygenated protohemeW. Robert. Scheidt and J. L. HoardCite this: J. Am. Chem. Soc. 1973, 95, 25, 8281–8288Publication Date (P…
The power-law and constant-loss theories of secondary electron emission have been modified to include the effects of secondary scattering within the solid. For power-law exponent values of 1.35, 1.66, and 2.00, the scattering effects reduced penetration depths at maximum yield by almost a factor of 2 and decreased the…
A new magnetic symmetry of the rare-earth orthochromites and orthoferrites ($\mathrm{RM}{\mathrm{O}}_{3}$) below the second N\'eel temperature due to the reordering of the rare-earth spins is proposed. It is shown that the magnetic symmetry group is lowered to the subgroup of index two, thereby keeping the unit cell i…
Thermal decomposition of silicon diimide, Si(NH) 2 , in vacuum resulted in very‐high‐purity, fine‐particle‐size, amorphous Si 3 N 4 powders. The amorphous powder was isothermally aged at 50° to 100° intervals from 1000° to 1500°C for phase identification. Examination of ir spectra and X‐ray diffraction patterns indica…
In recent years a wide variety of methods has been used to describe the polarization characteristics of ultra low frequency (10−3 to 1 Hz) magnetic fields. This paper gives a more complete outline of some of the descriptions derived from the spectral matrices of n-variate stochastic processes. The matrices are expande…
(1973). Quantum properties of surface space-charge layers. C R C Critical Reviews in Solid State Sciences: Vol. 4, No. 1-4, pp. 499-514.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectron spectroscopy for chemical analysis of nickel compoundsC. A. Tolman, W. M. Riggs, W. J. Linn, C. M. King, and R. C. WendtCite this: Inorg. Chem. 1973, 12, 12, 2770–2778Publication Date (Print):December 1, 1973Publication History Published online1 May 2002Published in…
Abstract Aqueous solutions of poly(vinyl alcohol) were submitted to varying doses of electron beam irradiation. By modification of the classical Flory‐Huggins equations appropriate to the initial state of solution of the polymer, the molecular weight between crosslinks, M c , was calculated as a function of radiation…
The existence of depolarization fields in thin ferroelectric films is experimentally demonstrated by investigating an unconventional electrode-ferroelectric configuration consisting of a triglycine sulphate (TGS) film sandwiched between a gold and a doped-silicon electrode. Due to nonidentical electrodes, the compensa…
The phonon dispersion relations of ZrC, NbC, HfC, TaC, and UC are investigated using a phenomenological-model theory. For the transition-metal carbides, a shell model with a free-electron screening is used to describe the over-all shape of the phonon curves. The results strongly support the "covalent model," where the…