bluuebunny/crossref_metadata_2025 huggingface dataset:
Behavioural response of larval Atlantic menhaden to different rates of temperature change
Authors: De Vries M. C. , Forward R. B. , Hettler W. F.
Published: June 2006

Larval Atlantic menhaden Brevoortia tyrannus, spawned off North Carolina (U.S.A.) during the winter, undergo cross‐shelf transport from the western Gulf Stream edge to coastal bays and estuaries. Variation in water flow direction with depth provides larvae the opportunity to enhance shoreward transport, if they can regulate their depth behaviourally. Temperature, which normally decreases with depth on the continental shelf, is one possible cue for depth regulation. Laboratory‐reared larval menhaden of two different ages were exposed to varying relative rates of temperature increases and decreases, which were presented from both above and below the larvae. Temperature decreases from below caused an ascent response in both young and old larvae, but neither responded to this cue from above. The minimum (threshold) relative rates of decrease for initiating ascents were similar (7.9 × 10−2, 10.7 × 10−2° C min−1) for both age larvae as were the minimum absolute amounts of decrease that must occur before a response (0.1, 0.05°C). Young larvae did not respond to a temperature increase, while old larvae ascended regardless of whether the increase was presented from above or below. Threshold relative rates of increase were 8.59 × 10−2°C min−1 from below and 14.79 × 10−2° C min−1 from above. The threshold rates and range of larval speeds during vertical movements were used to calculate vertical temperature gradients that could be perceived. These values were compared to measured gradients in areas inhabited by menhaden larvae. On the continental shelf, detectable temperature gradients appear common for temperature decreases that would occur upon descending and temperature increases upon ascending. However, it is uncommon for larvae to encounter temperature increases upon descending that would initiate an ascent response. These results support the hypothesis that menhaden larvae are capable of using temperature gradients for depth regulation.
Electroporation of abalone sperm enhances sperm‐DNA association
Authors: Sin F. Y. T. , Mukherjee U. K. , McKenzie J. C. , Sin I. L.
Published: June 2006

The ability of sperm from the black‐footed abalone Haliotis iris to take up foreign DNA in solution has been demonstrated. The efficiency of DNA uptake is related to the conditions of electroporation, including field strength (625 V cm−1, 1000 V cm−1), pulse length (18.6 ms, 27.4ms) and number of pulses (1, 2), and DNA concentration (20, 100 μg ml−1). Sperm motility decreased with increased field strength and pulse number. At a field strength of 625 V cm−1, neither the pulse length nor pulse number enhanced DNA uptake. A 40% enhancement in DNA uptake was observed when the sperm were shocked at 1000 V cm−1 with two long pulses (27.4 ms each). Linear regression analysis revealed that pulse number (p= 0.013) and field strength (P=0.039) were the most important factors in sperm–DNA interaction. Higher DNA concentration enhanced sperm DNA uptake irrespective of field strength, pulse length and pulse number. The optimal electroporation conditions for DNA uptake were 1000 V cm‘, with two pulses of 27.4 ms each, and a DNA concentration of 100 μg ml−1.
Gene diversity analysis of mitochondrial DNA, microsatellites and allozymes in landlocked Atlantic salmon
Authors: Tessier N. , Bernatchez L. , Presa P. , Angers B.
Published: June 2006

This study investigates the patterns of genetic diversity detected in allozymes, mtDNA, and microsatellites, in order to assess their relative efficacy to differentiate sympatric landlocked salmon populations and to estimate changes in genetic diversity between wild and first‐generation hatchery fish. Overall, the three genetic markers indicated a genetic differentiation between two sympatric populations of Lake Saint‐Jean, Québec. MtDNA and microsatellites also showed significant differences between wild and first‐generation hatchery fish originating from the same river. Allozyme analysis was the most limited approach due to the low genetic diversity detected and the necessity to kill specimens. Although low polymorphism was found in mtDNA, it was the most discriminant marker between wild populations. Microsatellite analysis appears to be a promising approach due to its high sensitivity in differentiating wild populations, in detecting changes in allele composition between wild and first‐generation hatchery fish and its potential for increased resolution by augmenting the number of polymorphic loci. Given the benefits and disadvantages of the three methods, the combination of mtDNA and microsatellite analyses will best address our research objectives.
SELENIUM BLACK GLASS*
Authors: Austin Chester R. , Sullivan John D.
Published: June 2006

A black glass was made by melting a soda‐lime‐silica glass under a reducing atmosphere with the addition of 0.6% of selenium and 0.1% of cobalt carbonate, CoCOs. The light absorption of a specimen about 0.01 inch thick in the range of 400 to 750 mp was superior to that of commercial black glass. The maximum transmission was 27% at 750 mp. The use of nickel and iron oxides is less effective than cobalt oxide for obtaining selenium black glass.
Thermal Shock Analysis of Spherical Shapes
Authors: CRANDALL W. B. , GING J.
Published: June 2006

A method is described for studying the thermal shock characteristics of a brittle material. An analysis of the thermal stresses developed in a homogeneous isotropic solid sphere has led to the formulation of an equation relating the physical properties of the body to the temperature difference causing failure and time to maximum stress in a single‐cycle unsteady‐state test. The thermal shock test consisted of plunging a sphere at one uniform temperature into a medium at another temperature. If fracture occurred, the time to fracture was recorded. A large number of tests were run to determine the temperature difference which caused 50% of the spheres to fracture. The thermal shock relationships were tested using a high‐alumina body. The physical properties relating to the thermal shock equations were measured, and calculated temperature differences causing failure and times to maximum stress were compared with measured values. Sufficient agreement was found to lend support to the theory.

A method has been developed for studying the thermal shock characteristics of a brittle substance. The method consists of a single‐cycle test of unsteady‐state nature. Two testing conditions have been selected, one having a rather high surface heat transfer coefficient in a liquid bath and the other having a small finite surface heat transfer coefficient in an air bath. These two conditions are at either extremes regarding the thermal shock usually given a substance in practice.

The only fair agreement found in the calculated and experimental data indicates that further investigation is necessary. The importance of certain factors, such as time to maximum stress, which was found to be in rather good agreement for the salt bath heat transfer, cannot be overlooked. There are many applications in the high temperature‐high stress field in which the concept of time to maximum stress might well be examined. For example, when repeated high‐temperature heatings are made on a refractory piece, the cycling might be arranged so that the time to maximum stress was never reached for the particular heating cycle, although the (ΔT) was higher than that necessary to cause failure.

Much is to be learned from this type of study which may be applied to actual situations. It must be emphasized, however, that this work has been conducted on one single set of conditions and the factors found here do not necessarily apply to other situations.
Surface Energies of Solid Oxides and Carbides
Authors: LIVEY D. T. , MURRAY P.
Published: June 2006

The surface energies of the alkali halides are considered in relation to various parameters such as lattice energy, molar volume, and heat of formation. The conclusions derived are applied to a consideration of the surface energies of the oxides, which range in value from 250 ergs per sq. cm. for PbO to > 1420 ergs per sq. cm. for BeO. Agreement is generally good between the predicted value from those relations and the available data except for those oxides which contain heavy‐metal ions, such as Cd++ and Pb++, where polarization of the metal ion tends to produce surfaces of lower energy, and those oxides containing cations of high polarizing power, such as B3+ and Si4+, where polarization of the oxygen anions and surface screening of the cations also produce low‐energy surfaces. The surface energies of the oxides are compared with those of the refractory monocarbides as determined from wetting experiments. The surface energies of the monocarbides range in value from 800 ergs per sq. cm. for ZrC to 1675 ergs per sq. cm. for VC and show a linear relationship with the heat of formation.
Relation Between Refractive Index and Elastic Moduli of a Borosilicate Glass After Heat‐Treatment
Authors: SPINNER SAM , NAPOLITANO ALBERT
Published: June 2006

Several specimens of a borosilicate glass were subjected to a series of different annealing schedules and the refractive indices and elastic moduli were measured and compared after each heat‐treatment. The elastic moduli were determined by a dynamic resonance method at frequencies both within and slightly above the sonic range. The refractive indices were measured on the Grauer refractometer. A linear relation was found to exist between these two properties for specimens with different heat‐treatments. A linear relation has already been established between refractive index and density by several investigators. This indicates that a single fictive temperature (τ) scale can be used to characterize the condition of a glass with respect to three properties: index of refraction, density, and elastic moduli.
Phase Equilibrium Studies in the System Iron Oxide‐Al2O3‐Cr2O3
Authors: MUAN ARNULF , SÖMIYA SHIGEYUKI
Published: June 2006

Subsolidus phase relations in the system iron oride‐Al2O2‐Cr2O3 in air and at 1 atm. O2 pressure have been studied in the. temperature interval 1250° to 1500°C. At temperatures below 1318° C. only sesquioxides with hexagonal corundum structure are present as equilibrium phases. In the temperature interval 1318° to 1410°C. in air and 1318° to 1495° C. at 1 atm. O2, pressure the monoclinic phase Fe2O3. Al2O3 with some Cr2O3 in solid solution is present in the phase assemblage of certain mixtures. At temperatures above 1380°C. in air and above 1445°C. at 1 atm. O2 pressure a complex spinel solid solution is one of the phases present in appropriate composition areas of the system. X‐ray data relating d‐spacing to composition of solid solution phases are given.
Oxidation of Silicon Carbide
Authors: JORGENSEN PAUL J. , WADSWORTH MILTON E. , CUTLER IVAN B.
Published: June 2006

The rate of oxidation of silicon carbide was measured in an atmosphere of dry oxygen between 900° and 1600°C. The rate was studied by using a thermogravimetric apparatus and was found to be diffusion controlled. The products of oxidation were amorphous silica and cristobalite, depending on the temperature. The effect of surface area was determined, and a correlation between the various sizes was made with the aid of an equation derived on the assumptions that (1) the reaction was diffusion controlled, (2) the particles were essentially spherical, and (3) the interfacial area was constantly changing. The presence of water vapor in the gaseous atmosphere was found to be extremely critical.
Studies in Lithium Oxide Systems: III, Liquid Immiscibility in the System Li2O‐B2O3‐SiO2
Authors: SASTRY B. S. R. , HUMMEL F. A.
Published: June 2006

Glasses within the ternary system Li2O‐B2O2SiO2 containing less than 25.6% Li2Ocan be broadly classified into three groups according to their behavior during cooling or heating. One group, containing either more than 18% Li2Oor less than 20% SiO2, yields clear glasses during slow or rapid cooling. The second group, containing approximately 5 to 15% Li2O and 26 to 90% SiO2, yields dense white opal glass during slow or rapid cooling. The third group, located at the outer edge of the second group, cools to room temperature as clear glasses but develops opacity when reheated to temperatures between 550° and 8800°C. It has been shown by electron microscopy that the opacity is due to liquid immiscibility, the matrix glass containing well‐formed spheres of the dispersed phase. Some of the clear glasses of both groups have been shown to consist of two immiscible phases. The size of the dispersed units in the spontaneous opal glasses and also the reheat opal glasses can be controlled by the variation of the reheat treatments. The phase separation reported here is beyond the resolution of the petrographic microscope and can be detected only with the high resolution of the electron microscope. Accessory evidence is given to show that the phases are non‐crystalline.
Formation of BaTiO3 from BaCO3 and TiO2 in Air and in CO2
Authors: TEMPLETON LIESELOTTE K. , PASK JOSEPH A.
Published: June 2006

The formation of BaTiO3 from equimolar BaCO3 and TiO2 (rutile) mixtures was studied in air and in CO2. A small amount of BaTiO3 is formed first directly from BaCO3 and TiO2 at the surface of contact. From then on it is a diffusion‐controlled reaction, and both BaTiO3 and Ba2TiO4 are produced, with Ba2TiO4 being formed in much larger amounts. In 1 atmosphere of CO2, the intermediate Ba2TiO4 was suppressed up to a temperature of about 1100°C. in agreement with thermodynamic calculations. Ba2TiO4 reacts fast with 1 atmosphere of CO2 below about 1100°C. to produce BaTiO3and BaCO3
Sintering of High‐Purity Nickel Oxide, II
Authors: IIDA YOSHIO , OZAKI SHUNRO
Published: June 2006

The effects of particle size, compacting pressure, additives, and mode of preparation on the sintering of nickel oxide are presented. A low calcining temperature results in a high bulk density of a sintered compact. No appreciable change in the rate of sintering is found above 1000 kg. per sq. cm., whereas the unheated density increases with increasing pressures. Additions of CaO promote sintering, additions of Na2O, Fe2O3, and Al2O3 retard sintering, and CeO2 and Ag2O have no effect; B2O3 accelerates grain growth but retards densification. Nickel oxide from oxalate has a small rate of sintering as compared with nickel oxides from hydroxide, nitrate, and carbonate. The effects of the mode of preparation of nickel oxide are discussed in view of the activation energy of electronic conductivity and particle size.
Space‐Charge Development in Glass
Authors: PROCTOR T. M. , SUTTON PAUL M.
Published: June 2006

Data are given that graphically demonstrate space‐charge build‐up in a glass containing alkali and in a glass relatively free of alkali. The observed potential distributions show a decided asymmetry and have large potential drops near the electrodes with a linear potential change near the center of the sample. The observations qualitatively fit the expected theoretical distributions, according to Proctor and Sutton, for material having cations mobile and anions essentially immobile. Crude estimates arising from comparison with the theory yield carrier concentration near 2 × 1016 per cm3. mobility of the cation near 3 × 10‐6 cm.2 per volt second, and diffusion constant near 2 × 10‐6 cm.2 per second. These mobility and diffusion values are two orders of magnitude larger than values computed from conductivity data or computed from measurements of the diffusion coefficient for sodium cations, both in simple alkali silicates. According to the theory, these higher values are perhaps reasonable, since they are associated with only the more mobile portion of the cation population.
Determination of Spectral Emissivity of Ceramic Bodies at Elevated Temperatures
Authors: BLAIR G. RICHARD
Published: June 2006

A rapid and very simple technique using induction heating is reported for obtaining the spectral, or total, emissivity of a ceramic material up to its melting point. The measurement system employs a PbS detector, in conjunction with a sensitive galvanometer. Spectral emissivity data are shown for several alumina bodies and for three rare‐earth oxides, erbium, samarium, and gadolinium, up to 1700°C.
Phase Relations in the System Iron Oxide—Cr2O3 in Air
Authors: MUAN ARNULF , OMIYA SHIGEYUKI
Published: June 2006

The quenching method has been used to determine approximate phase relations in the system iron oxide‐Cr2O3 in air. Only two crystalline phases, a sesquioxide solid solution (Fe2O3–Cr2O3) with corundum structure and a spinel solid solution (approximately FeO ·Fe2O3–FeO – Cr2O3), occur in this system at conditions of temperature and O2 partial pressure (0.21 atm.) used in this investigation. Liquidus temperatures increase rapidly as Cr2O3 is added to iron oxide, from 1591°C. for the pure iron oxide end member to a maximum of approximately 2265°C. for Cr2O3. Spinel(ss) is the primary crystalline phase in iron oxide‐rich mixtures and sesquioxide (ss) in Cr2O3–rich mixtures. These two crystalline phases are present together in equilibrium with a liquid and gas (po2= 0.21 atm.) at approximately 2075°C.
Vibrational Spectra of Vitreous B2O3.xH2O
Authors: PARSONS J. L. , MILBERG M. E.
Published: June 2006

The infrared absorption spectra of boron oxide glasses of low and high water content have been obtained in the 400‐ to 4000‐cm.−1 region using thin films or fine powders dispersed in a liquid. A structural interpretation of the glass spectra has been made with the aid of the spectra of the closely related materials boric acid, orthorhombic metaboric acid, and partly deuterated boron oxide glass of high water content. It has been shown that the glass spectra are consistent with a random‐network structure in which each boron is triangularly coordinated by three oxygens and that the presence of water leads to weak hydrogen bonding between oxygen atoms. No evidence for a substantial amount of tetrahedral coordination of boron by oxygen has been found in glasses of either low or high water content.
Brittle‐Ductile Transition Temperatures in Ionic Crystals
Authors: MURRAY G. T.
Published: June 2006

The strain at fracture as measured in bending NaCl, LiF, and MgO has been shown to be markedly temperature dependent. Air aging, substructure, and grain boundaries act to elevate the transition temperature of NaCl. Aging in air increases the transition temperature of MgO, and this embrittlement can be removed by high‐temperature annealing followed by air quenching.
A Carbon Arc Image Furnace and Microscope for Studies at High Temperatures
Authors: NEWKIRK H. W. , BRENDEN B. B.
Published: June 2006

A description is given of the optical principles and the operational and radiation characteristics of a 10‐kw. carbon arc image furnace which employs paraboloidal mirrors 12 in. in diameter. The furnace was constructed for use in conjunction with an American Optical Company microscope having a working distance of 7.25 in. and a numerical aperture of 0.1. The maximum irradiance in the image was determined by photometry and by observing the stability of materials of known melting points. The experiments indicate that the maximum irradiance in the image is 2.1 watts per sq. mm., a flux density equivalent to the radiation from a black body at 2200°C. The value of the equipment for microscopy studies was demonstrated by recording on movie film the behavior of mixtures of uranium dioxide with silicon or silicon carbide at high temperatures. Selected photographs from the movie film are included in this paper. Stereo micrographs taken at room temperature show additional detail in the heated samples.
Strength and Static Fatigue of Abraded Glass Under Controlled Ambient Conditions: III, Aging of Fresh Abrasions
Authors: MOULD R. E.
Published: June 2006

The effect of aging under various conditions on the strength and static fatigue of freshly abraded specimens has been studied. For both grit‐blast and emery cloth abrasions the liquid nitrogen (fatigueless) strength increased with storage time after formation of the abrasions for specimens stored in liquid water or in an atmosphere containing water vapor. After 1 day of storage in water the strength increase was about 60% of the freshly abraded value for emery cloth abrasions and about 30% for grit‐blast abrasions. The aging depended strongly on the medium in which the specimens were stored and on the relative humidity when they were stored in air. In very dry air or vacuum the aging effect appeared to be eliminated. Static fatigue curves (strength vs. load duration) in water were measured for specimens containing fresh abrasions and aged abrasions. Ordinary aging did not change the static fatigue behavior of fresh abrasions. The liquid nitrogen strength and static fatigue also were studied for specimens which had been baked at 470°C. in high vacuum after being abraded. This treatment increased the fatigueless strength by approximately the same amount as aging in water. The rate of static fatigue, however, which was unaffected by ordinary aging, was reduced by a factor of approximately 25 for vacuum‐baked as compared with fresh abrasions. Possible mechanisms for aging are discussed in some detail. It is proposed that the observed aging effects on the fatigueless strength can be accounted for by an increase of the radii of the tips of the abrasion cracks in the surfaces of the specimens. The suppression of fatigue for the vacuum‐baked specimens is believed to be related to the non‐wettability of their surfaces which was observed in the course of the experiments.
X‐Ray Study of the Solid Solution of TiO, Fe2O3, and G, O3 in Mullite (3A12O3a2Si02)
Authors: MURTHY M. KRISHNA , HUMMEL F. A.
Published: June 2006

A study of the solid solution of TiO2, Fe2O3, and Cr203 in mullite was made by measuring the changes in lattice parameters and unit‐cell volume. Synthetic mullite (3O3‐2SiO2) was reacted with up to 12 weight % of the oxides at temperatures ranging from 1000° to 17000C. The approximate minimum temperature required for the formation of solid solution was 12000C. for Fe203 and 1400°C. for Cr2O3 and TiO3. The maximum amount of solid solution found was 2 to 4% TiO2 at 1600°C., 10 to 12% Fe2Os at 1300°C., and 8 to 10% CrZO3 at 1600OC. Lattice parameters and unit‐cell volumes for each solid solution series increased with increasing amounts of foreign oxide. There was good agreement between the calculated and observed increase in cell dimensions for the iron oxide series. Except in the case of titania, there was good agreement between X‐ray data and petrographic observations.
Apparent Thermal Conductivity of a Heterogeneous Ceramic Body Under Isothermal Conditions
Authors: WHITMORE D. H.
Published: June 2006

USING statistical arguments, Brown1 derived expressions for the apparent permittivity of a binary mixture of solid phases in terms of the volume fractions and the permittivitits of each phase. The purpose of the present note is to direct the attention of experimentalists working on heat‐transfer phenomena in ceramics to the fact that simple extensions of Brown's results will yield equations for the apparent thermal conductivity of a heterogeneow ceramic body at constant temperature, whether the heterogeneity arises from the existence of isometric pores in an otherwise homogeneous solid or as a result of two solid phases being present. It is demonstrated below that the averaging formula for the apparent thermal conductivity of a porous ceramic body derived by Loeb,2 and employed by Francl and Kingery, 2 is a consequence of terminating series expansions for the thermal conductivity after the fist term. Brown's generalized result is given by where, for the dielectric case, KO is the ratio of the polarization to the Lorentz field intensity and K is the ratio of averaged values of these quantities, A is the shape factor for the particles of the minor phase in a binary mixture, and VA is the volume fraction of that phase.
Microstructure of a Soda‐Lime Glass Surface
Authors: TICHANE ROBERT M. , CARRIER GERALD B.
Published: June 2006

Electron micrographs were made of replicas of a weathered soda‐lime glass surface before and after various chemical and fire polishing treatments. These micrographs were compared with an electron micrograph of a replica of a fractured soda‐lime glass surface which was used as a typically smooth surface. Using this comparison, the smoothest surfaces were formed by dilute hydrofluoric acid, dilute phosphoric acid, sodium citrate solution, a solution of the disodium salt of ethylenediaminetetraacetic acid, and a fire polish‐water wash combination. On the other hand, alkaline solutions tended to roughen the glass surface and leave residues on it. Selected electron micrographs are shown to illustrate the effect of these treatments on soda‐lime‐type glass.
Kinetics of Nickel Ferrite Formation
Authors: BLUM S. L. , LI P.‐C.
Published: June 2006

The rate of nickel ferrite formation is influenced by the milling technique and in the case of wet milling by the type of liquid media used. The reactivity of different types of α‐Fe2O3 of spherical shape decreases with an increase of the surface area ratio of α‐Fe2O3 to NiO. The particle shape of the iron oxides also affects their reactivity; cubical α‐Fe2O3 has the least reactivity in the formation of nickel ferrite. The validity of Jander's equation in ferrite formation is reviewed. Based on present findings the rate of ferrite formation is best represented by the equation dx/dt= (a‐x)/t, in which x is the percentage of ferrite formed, t the time, and a the kinetic isothermal reaction rate coefficient which is related to the surface area ratio of the reacting oxides. The application of the foregoing equation to the formation of magnesium ferrites from data found in the literature is also satisfactory.
Effect of Trace A12O3 on Transformation of Quartz to Cristobalite
Authors: CHAKLADER A. C. D.
Published: June 2006

The effect of additions of 0.22, 0.44, 0.88, and 1.76% A12O3 (Si4+/A13+ ratio of 200:1, 100:1, 50:1, and 25:1) on the transformation of Brazilian quartz to cristobalite was studied at 1500°, 1530°, and 1570°C. The smaller percentages of A12O3 (0.22 and 0.44%) catalyzed the transformation of quartz and the formation of cristobalite considerably. The rates of transformation of quartz with 0.88 and 1.76% A12O3 were slower than with 0.22 or 0.44%, indicating a critical A13+/Si4+ ratio where the catalytic effect was found to be maximum. This appeared to occur at about 0.5% A12O3. The transformation rate of quartz indicated that the reaction was first order. Cristobalite, however, showed two different rates; the initial rapid growth was followed by a slower rate. The point of changeover was found to be at about 30 ± 5% cristobalite. The critical nature of the A13−/Si4+ ratio at about 0.01 (or A12O3/SiO2± 0.005) may have some bearing on the properties of silica refractories with more or less than 0.5% A12O3.
Investigation of Rare‐Earth Doped Barium Titanate
Authors: TENNERY VICTOR J. , COOK RALPH L.
Published: June 2006

In this study the effect of additions of 0.0015 to 0.0030 mole fraction of rare‐earth oxides on the d.‐c. resistivity of sintered barium titanate was investigated. The substitution may be represented by (X2O3)M (BaTiO3)1‐M where X is the rare earth. The rare earths samarium, gadolinium, and holmium were introduced singly into the titanate, and the resistivity was measured as a function of temperature from −170° to +330°C. An anomalous increase near the tetragonal ‐ cubic transition temperature at 120°C. occurred which in some cases amounted to an increase in the resistivity of 4000 times the value in the tetragonal phase. The thermoelectric power of the material changed sign at the Curie temperature. The tetragonal phase exhibited n‐type behavior whereas the cubic phase was p‐type. The rhombohedra1 and orthorhombic phases exhibited conduction activation energies of the order of 0.2 e.v. whereas that in the tetragonal phase was approximately 0.1 e.v.
Conversion of Quartz to Tridymite
Authors: HOLMQUIST S. B.
Published: June 2006

The conditions under which tridymite becomes a stable phase have been reinvestigated. When quartz was heated with 2% alkali oxide, tridymite formed directly at 872° to 898°C. with Na2O, at 883° to 902°C. with K2O, and above 1005°C. with Li2O. Cristobalite occurred as an intermediate phase above 893°C. with Li2O, above 898°C. with Na2O, and above 902°C. with K2O. When quartz plus sodium chloride was heated in vacuum, tridymite did not form but cristobalite started to appear at 1050°C. The results showed that the formation of tridymite can be strictly a solid‐state process. New schematic tentative diagrams for the high‐silica region of binary systems are suggested. Quartz and cristobalite are regarded as the only stable crystalline phases of pure silica. Tridymite is pictured as a binary incongruently melting phase.
Relation Between Base Metal Composition, Surface Composition, Pickling Rate, and Direct‐On Adherence
Authors: RAHN H. N. , MAYER E. H. , FRAME J. W.
Published: June 2006

Changes in residual alloy concentration, particularly increases in copper and nickel, which take place in pickling were found to be due to the formation of a pickling film through galvanic plating of these elements dissolved in the acid. Before pickling, the steel surface was actually higher in copper and nickel than was the interior, owing to preferential oxidation of iron during mill processing. Pickling film buildup (such as surface copper) was found to have no direct telation to adherence. Slow pickling steels, however, on which adherence was less easily obtained, built up more copper on the surface; hence, an apparent correlation existed. Fast pickling steels, which gave good adherence with less metal removal than was required for slow pickling steels, showed much more surface roughening for the same amount of metal removal. This increased roughening is felt to be a contributing factor toward good direct‐on adherence.
Three Planes in the Quaternary System CaO‐ZnO‐Al2O3‐SiO2
Authors: SEGNIT E. R.
Published: June 2006

Equilibrium relations in part of the quaternary system CaO‐ZnO‐Al2O3‐SiO2 have been investigated by the quenching method. Liquidus surfaces and primary‐phase fields have been determined in planes containing respectively 8, 10, and 15% A12O3, as well as six quaternary invariant points. The minimum melting point in the system is 1030°± 5°C at a composition of 18.5% CaO, 22.5% ZnO, 8.2% A12O3, and 50.8% SiO2,. At this point the condensed phases in equilibrium are tridymite, willemite, melilite, anorthite, and liquid. The results have a bearing on reactions occurring in lead blast‐furnace slags, in some ceramic glazes, and in certain zinc‐bearing rocks and ores.
Compatibility of Hydrated Sodium MetasiIicate Glasses with Inorganic and Organic Compounds
Authors: BERTAUT EDGARD F.
Published: June 2006

By dehydrating crystalline Na2SiO3·9H2O, a very low melting glass of the approximate composition Na2SiO3·3H2O was obtained. The compatibility of selected inorganic compounds with this molten glass was found to be related to the nature of the cation or anion present in each compound. The behavior of organic indicator dyes in the glass melt provided further information on the nature of the molten glass, whereas the infrared spectrum of the glass gave an inconclusive result.
Constitution of Mixed‐Alkali Phosphate Glasses: Constitution of Lithium‐Rubidium Phosphate Glasses
Authors: MURTHY M. KRISHNA , WESTMAN A. E. R.
Published: June 2006

In a previous study of the constitution of lithium‐sodium‐potassium phosphate glasses slight but definite cationic effects were observed. The constitution of lithium‐rubidium phosphate glasses with n̄, the number average chain length, varying from 1.25 to 9.00 was determined by paper chromatographic methods to follow the effect of substituting the rather large rubidium ion (1.47 A) for the small lithium ion (0.68 A). Systematic changes were observed; these changes, however, were numerically small. With the increase in the rubidium substitution for lithium the pyrophosphate content of the glass decreased and the tripolyphosphate content increased. Glasses with n̄ values as low as 1.5 (Li/Rb = 1/1) could be made by quenching the platinum crucible containing the melt in water. The n̄= 1.25 glass, however, devitrified when thus made. It could be prepared only by the new copper‐block‐cooled strip furnace technique.
Calculation of Cohesive and Surface Energies of Thorium and Uranium Dioxides
Authors: BENSON G. C. , FREEMAN P. J. , DEMPSEY E.
Published: June 2006

The cohesive and surface energies of thorium and uranium dioxides were estimated theoretically by computations based on a Born‐Mayer type of model. The sensitivity of the results to changes in the data used for the calculations is illustrated and discussed.
A Reexamination of the Polymorphism of Ca3SiO5
Authors: MIYABE H. , ROY D. M.
Published: June 2006

Polymorphic transitions in CasSiO6 have been investigated by precise high‐temperature X‐ray diffractometer measurements and by differential thermal analyses. In addition to change caused by normal thermal expansion, three principal crystallographic transformations take place: α‐triclinic–β–triclinic (sluggish) in the range 550° to 700°C; 8‐triclinic‐monoclinic at 910°± 10°C; and monoclinic‐trigonal at 970°± 10°C. The sluggish 550° to 700° C reaction alternatively may be interpreted as two separate triclinic‐triclinic transitions, accompanied by broad endothermic heat effects at 575° and 675°C.
Effect of Silica on Transformations of Fibrillar Colloidal Boehmite and Gamma Alumina
Authors: ILER R. K.
Published: June 2006

The addition of silicic acid to fibrillar colloidal boehmite retarded the conversion at high temperature of gamma alumina to theta and alpha and permitted the formation of an intermediate kappa. Unusually sharp X–ray diffraction patterns for gamma, theta, and kappa transition aluminas are presented.
Molar Volume and Surface Tension of Fused Metaphosphate—Sulfate Systems
Authors: OWENS B. B. , MAYER S. W.
Published: June 2006

Molten oxides have been of potential interest as fuels for nuclear reactors. To obtain additional information about the constitution of these systems, the molar volume and surface tension of the NaPO4–Li2SO4, NaPO4–Na2SO4, NaPO4–Rb2SO4, and NaPO3–UO2SO4 solutions were determined for the NaPO2–rich region. The observed properties were found to vary linearly with temperature in all cases. Although the results of other types of investigations were found to be nonideal, the volume behavior of all the mixtures was additive.
Thermal Decomposition of Cerous Oxalate and Variation of Surface Area of the Products
Authors: RAO V. V. SUBBA , RAO R. V. O. , BISWAS A. B.
Published: June 2006

The thermal decomposition of hydrated cerous oxalate was studied in the temperature range 30° to 1000°C by measuring the surface area of the products and mass change at various stages. The products were characterized by infrared absorption and X‐ray diffraction analyses. Two peaks in the surface area vs. temperature curve were observed. The first peak was due to the decomposition of the oxalate, which caused an increase in surface area, followed by partial crystallization of the oxide which reduced the surface area. The increase in surface area in the region 440° to 650°C was attributed to the decomposition of the carbonaceous materials dispersed in the oxide matrix; it was followed by a decrease in area due to bulk sintering of the oxide.
Space Charge and Electrode Polarization in Glass, I
Authors: SUTTON PAUL M.
Published: June 2006

This is Part I of a two‐part series on space charge in glass. This part is primarily a review and covers the general nature of the observed phenomena, the relation of these phenomena to usual concepts such as dielectric constant and electrical conduction, and the present understanding of these phenomena in glass. This review serves to describe the background and motivation for the work set forth in Part 11, which is a discussion of recent theory and experiment on space charge in glass. Areas for further investigation also are suggested.
Oxidation‐Reduction Equilibria in Iron‐Containing Glass
Authors: JOHNSTON W. D.
Published: June 2006

The oxidation‐reduction equilibrium between ferrous and ferric iron in Na2O · 2Si02 glass melts was studied by equilibrating melts with various oxygen partial pressures. Exceedingly long equilibration times were required to obtain meaningful results. The reaction appears to be diffusion‐controlled and may be expressed as 202‐+ 4Fe3+$4 4Fe2++ O2. Data are presented in which the valence of iron varies from predominantly +3 to predominantly +2.
Semiconducting Oxide Glasses: General Principle for Preparation
Authors: MACKENZIE J. D.
Published: June 2006

A general principle for the preparation of semiconducting oxide glasses is presented. Some borates, phosphates, and germanates were prepared. The mechanism of electrical conduction was demonstrated to be electronic rather than ionic by (a) the absence of electrolysis, (b) the absence of electromotive force when the glass was used as an electrolyte, and (c) the magnitude of the activation energies for conduction.
Strengthening by Ion Exchange
Authors: NORDBERG MARTIN E. , MOCHEL ELLEN L. , GARFINKEL HARMON M. , OLCOTT JOSEPH S.
Published: June 2006

This paper is a brief review of the physical and chemical methods of strengthening glass, in particular that due to the large for small ion exchange resulting from treatment in molten salt at temperatures below the annealing range for the glass. Abrasion of treated glass is shown to reduce markedly the strength of experimental alkali‐lime‐silica glasses as well as commercial glasses of this and other types. Treated alkali‐alumina‐silica and alkali‐zirconia‐silica glasses, however, are less affected by abrasion. Strength after abrasion increases with alumina or zirconia content, reaching 117,000 psi for cane of a 35% alumina glass. The explanation for the aluminum or zirconium effect may involve an unusual ionic environment caused by their presence in the lattice.
Space Charge and Electrode Polarization in Glass, II
Authors: SUTTON PAUL M.
Published: June 2006

This paper is Part IT of a two‐part series reviewing the present understanding of space charge and electrode polarization in glass and the interrelations of these concepts with the usually measured electrical properties of glass. Emphasis is placed on a theory describing the distribution of static space charge in material having only a single mobile charge carrier. Charge dissociation and recombination are considered and the carriers are assumed to move under diffusion and conduction. The charge distributions predicted by the theory are discussed and are compared with the results of experiments which were undertaken specifically to verify essential features of the predictions. The theory is confirmed qualitatively by the observed charge distribution shapes and asymmetries. Quantitative confirmation is also shown in computed values of mobility, diffusion constant, and contact potential ratios. This theory has here been expanded to include a linearized ac treatment, and the phenomena predicted by this treatment fit the known data semi‐quantitatively. A large low‐frequency relaxation mechanism is predicted. Previous theory and experiment were briefly reviewed in Part I. In Part I1 the predicted and observed space charges are conceptually related to various phenomena such as conduction, electrode polarization, dielectric absorption, and dielectric loss. Needed improvements in the present theory and a number of ideas for more experiments are outlined in order to stimulate efforts to acquire a more detailed understanding of these phenomena.
The System AI2SiO5 at High Temperatures and Pressures
Authors: DeVRlES R. C.
Published: June 2006

Experiments on the system Al2SiO5 at high temperatures and pressures with the belt apparatus indicate that kyanite melts incongruently above about 1500°C at 25,000 bars to Al2O3 (corundum) plus liquid. The pressure‐temperature curves obtained by starting with either a 1/1 Al2O3/SiO2 gel or with kyanite are essentially identical but differ considerably from the results with andalu‐site and sillimanite. The structure of the starting material has considerable influence on the kinetics of the reaction and the metastable formation of corundum in this system. An “equilibrium” curve based on the andalusite‐sillimanite data is described by P= 33.8 × 10‐3T ‐ 26.4 (Pin kbars, Tin°C).
Effect of Gaseous Environment on Fracture Behavior of AI2O3
Authors: MOUNTVALA A. J. , MURRAY G. T.
Published: June 2006

The effect of various gaseous atmospheres (nitrogen, hydrogen, and water vapor) on the fracture strength of single‐crystal and poly‐crystalline A1203 was investigated. Sapphire specimens exposed to hydrogen and nitrogen at elevated temperatures and subsequently tested at room temperature did not become brittle or lose strength. Sapphire specimens exposed to moisture in a specific temperature range showed a definite impairment of strength in subsequent room‐temperature bend tests. The strength was recovered when the moisture‐exposed specimens were heated to 400°C. It is suggested that the loss of strength and the recovery are due to the formation and decomposition of a surface precipitate, presumably a hydrate of some type. Polycrystalline alumina (Lucalox) did not show any significant loss in strength when exposed to moisture.
Phase Relations in the System Lead—Oxygen
Authors: WHITE WILLIAM B. , ROY RUSTUM
Published: June 2006

Most of the known oxides of lead including the intermediate oxides Pb12O19 and Pb2O3 have been prepared under equilibrium conditions. Precise X‐ray powder data have been obtained for the intermediate oxide phases. Solid‐vapor equilibrium data have been obtained for reactions in the system lead‐oxygen over the range 200° to 900° C and 3 to 1400 bars Po2. Pressure‐temperature univariant equilibrium curves are presented for the reactions PbO2⇋ Pb12O19+ oxygen, Pb12O19⇋ Pb3O4+ oxygen, and Pb3O4⇋ PbO + oxygen. The enthalpies of reaction are, respectively, 26.8, 34.6, and 33.7 kcal per mole. Eutectic melting between PbO and Pb3O4 occurs at 875° C and 124 bars. A stability field for Pb2O3 exists above 1000 bars PO2 at 600° C. Approximate resistivity data are presented.
Dissolution in Ceramic Systems: 11, Dissolution of Aluminu, Mullite, Anorthite, and Silica in a Calcium‐Aluminum‐Silicate Slag
Authors: SAMADDAR B. N. , KINGERY W. D. , COOPER A. R.
Published: June 2006

Experimental measurements have been made on the rate of dissolution of sapphire, dense poly‐crystalline alumina, mullite, fused silica, and anorthite in a 20A12O3‐4OCaO‐40SiO2 slag at 1350° to 1500° C under conditions of free and forced convection. Dissolution rates and their temperature dependence were found to be controlled by transport within the liquid boundary layer. At low temperatures alumina is by far the most corrosion resistant; at higher temperatures differences between the refractories tested are less pronounced.
Phase Equilibria in the System MgO—MgCr2O4
Authors: ALPER A. M. , McNALLY R. N. , DOMAN R. C. , KEIHN F. G
Published: June 2006

The liquidus, solidus, and subsolidus in the system MgO‐MgCrz04 were redetermined. Petro‐graphic studies indicated that 47 wt% Cr203 could enter into the periclase lattice at about 235OO C. X‐ray and optical data showed that the solid solution decreased to 32 wt% Cr202 at 2165OC, 11 wt% at 1600°C, 5 wt% at 1400°C, 2.5 wt% at 1200°C, and 0 wt% at 1000°C. Petro‐graphic studies also suggested that picrochromite could contain about 5 wt% MgO in solid solution. The liquidus was much higher than has been indicated on previously published phase equilibrium diagrams.
High‐pressure Effects on Oxide Glasses: III, Densification in Nonrigid State
Authors: MACKENZIE J. D.
Published: June 2006

Densification of silica glass was carried out at IS kb and 2000°C and of boron oxide glass at 20 kb and 900° C. The subsequent annealing of the densified glasses was examined at atmospheric pressure. The annealing behavior of glasses densified in the nonrigid condition is shown to be drastically different from that of the rigidly densified materials. The annealing kinetics are discussed in terms of two different processes of volume flow.
Chemical Resistance of Refractories to AI and AI‐Mg Alloys
Authors: LINDSAY J. G. , BAKKER W. T. , DEWING E. W.
Published: June 2006

The chemistry of the reaction between molten aluminum alloys and some refractory oxides is discussed. High‐alumina brick containing 85, 94, and 99% Al2O3 periclase brick, and magnesia spinel brick were immersed for 48 hours in three aluminum alloys containing 0, 2.4, and 7.7% magnesium, respectively. All brick were discolored, although most of the discoloration disappeared after reheating at 1000°C in an oxidizing atmosphere. Only the 85 and 94% brick, which contained silica, showed permanently darkened reaction rims. X‐ray diffraction analysis of these darkened areas showed that the alloy containing 7.7% magnesium caused periclase formation in the rim whereas the alloy containing 2.4% magnesium produced spinel. Commercial aluminum caused only a decrease in the mullite content of the darkened area. Magnesia spinel and periclase were unaffected by all the alloys tested.
Formation of Lead Zirconate‐Lead Titanate Solid Solutions
Authors: MATSUO YOSHIHIRO , SASAKI HIROMU
Published: June 2006

Formation of the Pb(Zr,Ti)O3 solid solution in the system PbO‐TiO2‐ZrO2 was studied by chemical analysis and X‐ray powder diffrac‐tometry. Only PbTiO3 and Pb(Zr,Ti)O3 were found as reaction products. The following three elementary reactions seemed to be reasonable for the formation of the Pb(Zr,Ti)O3 phase: PbO + TiO2→ PbTiO3, PbTiO3+ PbO + ZrO2→Pb(Zr1‐λTiλ)O3, and Pb(Zrl‐λTiλ)O3+ PbTiO3→ Pb(Zr1‐λ′Tiλ′)O3 (λ<λ′).
Dehydroxylation of Kaolinite, Dickite, and Halloysite: DTA Curves Under PH2O= 15 to 10,000 psi
Authors: WEBER JON N. , ROY RUSTUM
Published: June 2006

The dehydration temperature of the kandites, observed by high‐pressure DTA, increases with increasing water pressure to about 400 psi. Above this pressure, dehydration occurs at lower temperatures. Under experimental conditions, the dehydroxylation of kaolinite, dickite, and halloysite is metastable, with dickite persisting in the stability field of kandite + water to temperatures as much as 265°C above its upper stability limit.
Phototropy of Reduced Silicate Glasses Containing the 570 m°Color Center
Authors: SWARTS E. L. , PRESSAU J. P.
Published: June 2006

Simple silicate glasses of high purity and melted under strong reducing conditions develop a characteristic visible color center on absorbing ionizing radiation. This center peaks at 570 mμ in soda‐silica glasses but changes position depending on the specific modifier ions. The center grows to relatively large concentrations in glass irradiated by long wavelength ultraviolet light but also decays rapidly at room temperature, imparting phototropic response to the glass. The 570 mμ center probably does not require specific ion impurities; however, minor additions of Ce, Eu, and Zr enhance its formation in certain base compositions. Transition series elements, even in small concentrations, inhibit the center. Sustained irradiation by ultraviolet light leads to lower equilibrium concentrations of the center and hence to fatigue of phototropic response.
Proof‐Testing Graphite and Its Design Implications
Authors: DALLY J. W. , HJELM L. N.
Published: June 2006

The influence of proof‐testing on the behavior of CFW graphite is described and the improvements in the strength associated with a given probability of failure are established. Damage induced in the graphite by the proof‐test process was examined in more detail by conducting low‐cycle fatigue tests. Fatigue deterioration of the strength of the graphite is cumulative and the number of cycles of load significantly influences the probability of failure. A modified Gaussian distribution function accounts for the influence of both the stress and the number of load cycles on the probability of failure.