bluuebunny/crossref_metadata_2025 huggingface dataset:
Genetic stock identification of Atlantic salmon using single locus minisatellite DNA profiles
Authors: Galvin P. , McKinnell S. , Taggart J. B. , Ferguson A. , O'Farrell M. , Cross T. F.
Published: June 2006

The successful application of genetic stock identification (GSI) in mixed fisheries for Pacific salmon species has demonstrated clearly the potential of the approach as an aid to effective management of salmonid populations. Low levels of genetic variability detectable by protein electrophoresis have limited its utilization in Atlantic salmon Salmo salar management. However, recent developments in the detection of highly variable minisatellite loci, mean that the GSI technique is now applicable in this species. An extensive baseline survey of the River Shannon system in Ireland, involving a total of 1252 juvenile Atlantic salmon collected from nine tributaries, screened for three highly variable minisatellite DNA loci (Ssa‐A45/1, Ssa‐A45/2/1 and Str‐A9), presented a suitable database to assess this type of mixed fisheries approach. Allozyme analysis, carried out on the same fish, allowed the performance of GSI on minisatellite DNA data to be compared directly with conventional data using simulations. Initial tests involved the creation of ‘mixture samples’ of specified compositions from the database, to determine the bias involved and the degree of precision achievable in the estimation of the composition of the mixture sample. Iterations of this procedure, simulated resampling of a mixture stock, thus enabled bias and precision to be estimated. The effect of size of the mixture sample was also assessed in this way. It was then possible to examine the compositions of actual mixture samples (using minisatellite DNA analysis only), which consisted of 200 unmarked grilse (one sea‐winter) and 50 unmarked multi‐sea‐winter salmon, collected as they passed upstream through traps located near the base of the system. Sampling in this case involved the non‐destructive collection of adipose fin cores (an important consideration as valuable broodstock were involved). The initial analysis revealed that allozymes require much larger sample sizes than minisatellites to achieve comparable accuracy and precision. It also appeared that GSI analysis, based on just three minisatellite loci, can provide very useful estimates of stock composition, even from a mixture sample comprising of stocks from within a single river system.
Studies in Lithium Oxide Systems: IX, Li2o‐Al2O3‐TiO2
Authors: KIM K. H. , HUMMEL F. A.
Published: June 2006

Compatible phases in the system Li2O‐Al2O3‐TiO2 at various temperature levels were determined mainly by solid‐state reactions for the portion of the ternary system bounded by Li2O Al2O2, Li2O.TiO2, Al2O, and TiO2. The existence of a ternary compound, Li2O.Al2O3.4TiO2, and nine joins was established. The ternary compound has a lower limit of stability at 1090°± 15°C. and dissociates and recombines rapidly at 1380°± 15°C.
Processing of Positive Temperature Coefficient Thermistors
Authors: SAUER H. A. , FISHER J. R.
Published: June 2006

The controlled addition of impurities such as lanthanum in barium titanate and barium strontium titanate systems results in thermistor materials which have large positive temperature coefficients of resistance over controlled temperature ranges. The resistivity in these systems is sensitive to the concentration of the trace additives, to undesirable impurities in the raw materials, and to the sintering and maturing conditions. Ceramic procedures well adapted to prepare these thermistors reproducibly have been developed.
Mechanism of Solid‐state Reaction Between Magnesium Oxide and Aluminum Oxide and Between Magnesium Oxide and Ferric Oxide
Authors: CARTER R. E.
Published: June 2006

Inert marker experiments have shown that the solid‐state reactions forming MgAl2O4 and MgFe2O4 occur by counterdiffusion of the Mg2+, Fe3+, and A13+ ions through the relatively rigid oxygen lattice of the spinel or ferrite. It is suggested that earlier claims that ZnAl2O4 forms by diffusion of Zn2+ and O2‐ ions were probably due to a splitting of the markers, leaving some marker on the specimen surface. Pores in one component of a reacting couple are shown to serve as inert markers. The formation of those materials, e.g., ferrites and stannates, which dissolve marker materials can now be studied.
Reaction Kinetics of Polycrystalline Yttrium Iron Garnet
Authors: HOLMQUIST W. R. , KOOI C. F. , MOSS R. W.
Published: June 2006

The formation of yttrium iron garnet, Y3Fe2‐(FeO4)3, starting with (1) Fe2O3 and Y2O3 and (2) Fe3O4 and Y2O3, was studied as a function of temperature and time by means of magnetic moment and X‐ray measurements. The reaction began at 600°C. and was completed at 1200°C. The perovskite phase appeared only between 600° and 800°C. Above 1200°C. only the garnet phase was present. The microwave line width and g‐factor at 9303 mc. per second were also measured and related to the preparation variables.
Properties of Soda Aluminosilicate Glasses: Coordination of Aluminum Ions
Authors: DAY DELBERT E. , RINDONE GUY E.
Published: June 2006

An X‐ray fluorescence technique has been used to study the coordination number of the aluminum ions in soda aluminosilicate glasses. The fact that the emission wavelength of the Kα line of aluminum is slightly different for aluminum ions in different coordination states is utilized in this technique. Using this small difference in wavelength, it is shown that, depending on the Al/Na ratio, the soda aluminosilicate glasses contain aluminum ions in either fourfold and/or sixfold coordination. The X‐ray fluorescence measurements are shown to support the structural model which has been proposed for the soda aluminosilicate glasses to explain the behavior of some of their physical properties.
Stresses in Glass Produced by Nonuniform Exchange of Monovalent Ions
Authors: KISTLER S. S.
Published: June 2006

A study was made of the rate of diffusion of alkali ions into a soda‐lime glass from nitrate melts, and the distortion of glass disks produced by the stresses thus developed was measured using an interference technique. A maximum of 124,000 psi was produced when Na+ was replaced by K+. Tensile stresses accompanying the replacement of a large ion by a smaller one or by leaching ions out of the surface with water or dilute acid may be large and can destroy the glass.
Action of Alkali and Alkali‐Vanadium Oxide Slags on Alumina‐SiIica Refractories
Authors: RIGBY O. R. , HUTTON R.
Published: June 2006

A series of alumina‐silica specimens ranging from pure alumina to pure silica was prepared. The specimens were then crushed and mixed with either sodium carbonate or a mixture of sodium carbonate and vanadium pentoxide. The mixtures were pressed into cylinders which were heated at temperatures between 800°C and either 1700° C or the melting point. Changes in dimensions were noted and the reaction products were studied by X‐ray diffraction. Some of the specimens showed large volume expansions associated with the formation of sodium alumi‐nate. Reaction products detected included al‐bite, nepheline, and the mineral jadeite.
Electrical Conductivity in the ZrO2‐Rich Region of Several M2O3—ZrO2 Systems
Authors: STRICKLER D. W. , CARLSON W. G.
Published: June 2006

The electrical conductivity of M2O3‐ZrO2 compositions containing 6 to 24 mole % M2O3, where M represents La, Sm, Y, Yb, or Sc, was examined. Only Sm2O3, Y2O3, and Yb2O3 formed cubic solid solutions with ZrO2 over most of this substitutional range. Scandia forms a wide cubic solid solution region with ZrO2 at temperatures above 130°C whereas the cubic solid solution region at room temperature is narrow (6 to 8 mole % Sc2O3). Lanthana additions to ZrO2produced no fluorite‐type cubic solid solutions within the compositional range investigated. Generally, the electrical conductivity of these cubic solid solutions increased as the size of the substituted cation decreased and the electrical conductivity for each binary system attained a maximum at about 10 to 12 mole % M2O3.
Hot Hardness of Selected Borides, Oxides, and Carbides to 1900°C
Authors: KOESTER R. D. , MOAK D. P.
Published: June 2006

The hot hardness of TiB2, W2B5, ZrB2, HfB2, ZrO2, Al2O3, NbC, Tic, TaC1‐x, HfG1+x, (Ta0.8Hf0.2)C1+x, W2C, and (W0.65Cr0.14Re0.14Ta0.07)2C of <95% density was determined to temperatures approaching 1900°C. In all cases, the hardness decreased rapidly with increasing temperature. The data are compared to those available in the literature.
Monoxide‐Type Compounds of Uranium and Plutonium: I, Oxycarbides
Authors: TAYLOR K. M. , ANDERSEN J. C. , STRASSER A. , STAHL D. , FORBES R. L.
Published: June 2006

Oxycarbides having the face‐centered cubic MO‐type structure were formed by the controlled reduction of mixtures of PuO2 and UO2 in helium and in vacuum. Carbon, UC, and U were used as reducing agents. Carbon appeared to be necessary to stabilize the monoxide structure. The maximum oxygen content for essentially single‐phase (U0.9Pu0.1)(OxC1‐x) is x= 0.4. Oxycarbide compositions with higher oxygen contents (approaching x= 0.6) can be produced but these products are multiphase containing appreciable quantities of a dioxide, MO2‐x in carbon reduction, and MO2‐x plus metal in U plus UC reduction. The single‐phase oxycarbides lack sufficient water‐corrosion resistance to be used as fuels in water‐cooled reactors; however, their thermal conductivity appears to be higher than that of the dioxide fuels.
Structure Transition in Alkali Silicate Glasses
Authors: LACY E. D.
Published: June 2006

The logarithm of measured high‐temperature fluidities is related to the square of the calculated probability of finding a nonbridging oxygen in a randomly chosen SO4 group. This is interpreted in terms of a flow mechanism (gliding) dependent on juxtaposition of two such oxygens. A theory of the glass transformation is developed. On cooling, the coordination number of nonbridging oxygens increases until, ideally, at T, each touches three oxygens of an external Si04 group (stabilization). Below this temperature, thermal expansion/contraction contains no coordination change component. These changes constitute a second‐order transition. Observed volume data are in agreement with hypothesis. On this view, stabilization creates vacant tetrahedral environments adjacent to existing ones. Migration of glass‐forming ions to these empty sites can unlock the structure and permit the operation of a new set of flow processes. The coordination requirements for stabilization severely restrict the types of local arrangement possible at high silica contents, and therefore reduce the configurational entropy and induce unmixing. The overall transformation is composite in character. Rather extensive bond rearrangement and unmixing (when present) are features of first‐order kind.
Kinetics of Crystallization in Li2O‐SiO2 Glasses
Authors: FREIMAN S. W. , HENCH L. L.
Published: June 2006

The kinetics of crystallization of Li2Si2O5 from glasses in the Li2O‐SiO2 system were studied using quantitative X‐ray diffraction. Analysis of the data using the Johnson‐Mehl‐Avrami equation showed that crystallization occurred through the nucleation and growth of rods. The spherulitic nature of the crystals was substantiated by petrographic examinations of the partially crystalline glass. Analysis of the temperature dependence of the crystallization rate using a modification of the Johnson‐Mehl‐Avrami equation showed that the activation energy for nucleation was a function of composition and thermal treatment.
Brittleness and Impact Resistance
Authors: STEVERDING B.
Published: June 2006

Impact resistance and brittleness have often been confused as identical properties for ceramic materials. This study determines the conditions under which the static characteristic of brittleness diverges from the dynamic characteristic of impact resistivity. It is shown that the parameter most responsible for the difference between static and dynamic material behavior is the ratio of shock duration to relaxation time, but that material size and geometry can also be decisive. An amplification factor is derived which indicates to what extent ductile materials may be “overstressed”—beyond the static limit of brittle materials—before fracture occurs.
Kinetics of Leaching of Lead Glass by Ethylenediaminetetraacetic Acid
Authors: OLSEN DOUGLAS A. , JOHNSON RICHARD E. , KIVEL JOSEPH , ALBERS FRANK C.
Published: June 2006

Treatment of lead glass with a hot basic solution of the sodium salt of ethylenediaminetetraacetic acid (EDTA) was shown to remove lead from the glass surface. A mechanism is proposed whereby lead is removed by a two‐step reaction involving hydroxyl ions and EDTA. The rate constant and the overall heat of activation were estimated for this reaction. Potassium and silicon are also removed from the glass surface and show a dependence similar to that of lead removal. Potassium and silicon, however, do not form complexes with EDTA. Thus, it appears that lead removal weakens the silicate structure of the glass surface, allowing the potassium and silicon to be attacked and removed by hydroxyl ions and/or water. Experimental results indicate that the silicon released from the glass surface is in the form of silica.
Growth of Complex Oxide Single Crystals from Fluoride Melts
Authors: WEAVER E. A. , LI C. T.
Published: June 2006

Single crystals of a barium magnesium tantalate, a lead tantalate, calcium niobate, and potassium germanate were synthesized by the reactions of oxides and fluorides at high temperatures. The technique is very much like the flux method, except that some of the fluoride cations combine chemically with the oxide nutrients. Starting compositions and conditions for growth are given. The most probable reactions were calculated using free energies of formation with known thermo‐chemical data for an analogous system. Complex fluoride‐forming reactions, hydrolysis reactions, and reactions which form fluorides and oxyfluorides are possible. The reaction products were also studied by X‐ray analysis of the single crystal and polycrystalline products. Lattice parameters, space groups, and X‐ray powder patterns are presented for the single crystal materials.
Unified Theory of Thermal Shock Fracture Initiation and Crack Propagation in Brittle Ceramics
Authors: HASSELMAN D. P. H.
Published: June 2006

A fracture‐mechanical theory is presented for crack propagation in brittle ceramics subjected to thermal shock. The criteria of crack stability are derived for a brittle solid uniformly cooled with triaxially constrained external boundaries. Thermal stress crack instability occurs between two values of critical crack length. For short initial crack length, crack propagation occurs kinetically, with the total area of crack propagation proportional to the factor St2 (1‐2v)/EG, where St is tensile strength, v is Poisson's ratio, E is Young's modulus, and G is surface fracture energy. Under these conditions the newly formed crack is subcritical and requires a finite increase in temperature difference before propagation will proceed. For long initial crack length, crack propagation occurs in a quasi‐static manner and can be minimized by maximizing the thermal stress crack stability parameter Rst= [G/α2E]1/2, where α is the coefficient of thermal expansion. For heterogeneous brittle solids, such as porous refractories, the concept of an “effective flaw length” is introduced and illustrated on the basis of experimental data in the literature. The relative change in strength of a brittle solid as a function of increasing severity of thermal shock is estimated. Good qualitative agreement with literature data is found.
Substructure and Perfection in UO2 Single Crystals
Authors: CHAPMAN A. T. , CLARK G. W. , HENDRIX D. E. , YUST C. S. , CAVIN O. B.
Published: June 2006

The quality of UO2 single crystals grown by arc‐melting, by a modified floating‐zone technique (ICZG), and by vapor deposition was studied using etch‐pit patterns, electron microscopy, and X‐ray topography. These techniques complemented each other and indicated significant variations between the crystals grown by the different techniques. Both types of melt‐grown crystals contained extensive substructure and approximately 106 etch pits/cm2; finely dispersed inhomogeneities were found in the vapor‐grown crystals. Stoichiometry control during growth permitted a major improvement in the perfection of the ICZG crystals.
Polymorphic Behavior of Thin Evaporated Films of Zirconium and Hafnium Oxides
Authors: EL‐SHANSHOURY I. A. , RUDENKO V. A. , IBRAHIM I. A.
Published: June 2006

Polymorphism in thin evaporated films of zirconium and hafnium oxides was investigated from 100° to 1500°C by electron diffraction and transmission electron microscopy. The films have metastable cubic structures at room temperature and at moderate temperatures. Zirconium oxide, depending on temperature, exists in cubic, tetragonal, and monoclinic forms, whereas hafnium oxide transforms directly from the cubic to the monoclinic structure. The transformation temperatures depend on the oxygen partial pressure. Air annealing of thin films of ZrO2 and HfO2 lowered the temperature of transformation of the tetragonal and the cubic structure into the monoclinic structure by about 150° and 100°C, respectively. The cubic/tetragonal transformation of ZrO2 is monotropic, whereas the tetragonal monoclinic transformation occurs by the typical nucleation and growth mechanism. Determination of grain size in ZrO2 at the tetragonal/monoclinic transformation temperature showed that the transformation occurs when a constant grain size of about 800 Å is reached. The oxygen partial pressure, grain size, and temperatures at which the metastable phases exist were correlated. The rate of grain growth is enhanced by increase in oxygen partial pressure. The accelerated transformation in air is attributed to rapid attainment of the critical size; grain boundary energy is an important controlling factor in transformation.
Oxygen Diffusion in Nickel Ferrous Ferrite
Authors: O'BRYAN H. M. , DIMARCELLO F. V.
Published: June 2006

The diffusion coefficients of oxygen in single crystals of nickel ferrite with Fe/Ni=3.4 were determined as a function of oxygen stoichiometry between 1140° and 1340°C. The diffusion kinetics were followed by measuring the rate of exchange of 18O between the gas and solid slabs of ferrite, and the oxygen stoichiometry was established by controlling total pressure of oxygen in the gas phase. At higher oxygen contents, the diffusion coefficient is independent of stoichiometry and is given by D=10‐2.3exp cm2/s. At low oxygen contents the diffusion rate depends strongly on oxygen stoichiometry and is smaller. In polycrystalline ferrite the diffusion at 1197°C is 40 times faster than in single crystals but shows the same dependence on oxygen stoichiometry. Probable diffusion mechanisms are discussed.
Retrograde Solubility of Periclase, Forsterite, and Dicalcium Silicate
Authors: BIGGAR G. M. , O'HARA M. J.
Published: June 2006

Published phase equilibria data are used to demonstrate that for certain compositions, including some commercial magnesites, the amount of one crystalline phase present with liquid can increase as the temperature is raised. This effect is important for periclase with forsterite+spinel+liquid and for dicalcium silicate with merwinite+periclase+liquid; it may influence bonding in commercial refractories.
A General Model for the Intermediate Stage of Sintering
Authors: JOHNSON D. LYNN
Published: June 2006

A model proposed for intermediate‐stage sintering relates the densification rate to the instantaneous geometry in the compact and to the volume and grain‐boundary diffusion coefficients, despite concurrent surface diffusion, vapor transport, and/or grain and pore growth. Quantitative stereological methods can be used to measure the necessary geometric parameters. The suggested experiments would provide a detailed description of the evolution of the microstructure and calculated values for the grain‐boundary and/or volume diffusion coefficients.
Creep of Doped Polycrystalline Al2O3
Authors: SUGITA TADAAKI , PASK JOSEPH A.
Published: June 2006

Creep behavior of polycrystalline A12O3 doped with MgO + NiO, both as‐hot‐pressed in graphite dies and additionally annealed, was determined for 1300° to 1470°C and for 1000 to 15,000 psi in compression. The deformed specimens contained intergranular separations. Creep rates were proportional to stress to the 1.1 and 1.3 powers and were independent of grain size changes occurring during creep. The suggested creep mechanism is localized plastic deformation at stress concentration points accommodated by grain‐boundary separations initiated by grain‐boundary sliding.
Electrical Properties and Defect Structure of ThO2
Authors: BRANSKY I. , TALLAN N. M.
Published: June 2006

The electrical conductivity and thermoelectric power of highpurity polycrystalline ThO2 in thermodynamic equilibrium with the gas phase were measured as a function of temperature from 1000° to 1600°C and as a function of oxygen partial pressure from 1 to 10−22 atm. An n‐type electronic contribution to the conductivity is observed above 1400°C at low oxygen pressures. An analytic solution is presented for the oxygen pressure dependence of the total conductivity in the mixed ionicelectron hole conduction region observed at higher oxygen pressures. The activation energies for p‐type and ionic conduction are 1.0 and 0.9 eV, respectively. The combined conductivity and thermal emf data give a lower limit of ∼6 cm2/V‐s for the electron hole mobility.
Kinetics of Solid‐State Reaction of Bi2O3 and Fe2O3
Authors: MUKHERJEE JAHAR L. , WANG FRANKLIN F. Y.
Published: June 2006

Solid‐state reactions of equimolar mixtures of Bi2O3 and Fe2O3 from 625° to 830°C and their kinetics were investigated. The reaction rates were determined from the integrated X‐ray diffraction intensities of the strongest peaks of the reactants and products. The activation energy for the formation of BiFeO3 was 96.6±9.0 kcal/mol; that for a second‐phase compound, Bi2Fe4O9, which formed above 675°C, was 99.4±9.0 kcal/mol. Specific rate constants for these simultaneous reactions were obtained. The preparation of single‐phase BiFeO3 from the stoichiometric mixture of Bi2O3 and Fe2O3 is discussed.
Point Defects and Sintering of Lead Zirconate‐Titanate
Authors: ATKIN R. B. , FULRATH RICHARD M.
Published: June 2006

The crystal chemistry of point defects in lead zirconate‐titanate is discussed. The results are used to interpret sintering and grain‐growth behavior. Lattice vacancies are created thermally, by substitutional impurities with incorrect valences, and by changes in stoichiometry. Charged O vacancies are introduced when Al3+ replaces Ti4+, and charged Pb vacancies occur when Nb5+ replaces Ti4+. These vacancies are believed to be associated with the impurity ions and cause them to be adsorbed at grain boundaries. This behavior retards grain growth and thereby expedites densification. Aluminum ions (deficient valence) compensate for niobium ions (excess valence). These “paired” defects are not associated with vacancies and are not adsorbed; thus, they do not impede grain growth. Sintering follows Coble's model of bulk diffusion of vacancies from pores to grain boundaries. Oxygen vacancies are believed to be the slowest‐moving species. Aluminum: niobium compensation is confirmed by ferroelectric measurements. Doping with Al decreases the mobility of ferroelectric domain boundaries, whereas Nb increases it. Doping with both ions produces ferroelectric properties similar to those of the undoped material.
Structure and Mechanical Properties of Codeposited Pyrolytic C‐SiC Alloys
Authors: KAAE J. L. , GULDEN T. D.
Published: June 2006

Alloys of pyrolytic carbon and silicon codeposited in beds of fluidized particles were investigated. X‐ray diffraction measurements revealed only two phases, turbostratic C and β‐SiC. Since the C crystallites are oriented randomly, the C was macroscopically isotropic, with apparent crystallite sizes in the range found for pure C deposited under similar conditions. Transmission and scanning electron microscopy showed that the SiC was generally distributed as small particles which tended toward larger particles and continuous laminations at high SiC concentrations. The fracture stress and Young's modulus were measured in 3‐point bending; they increased continuously with increasing SiC content from values for pure isotropic carbons to values for chemically‐vapor‐deposited SiC.
Sintering of Ag‐Pd in the Presence of a Reactive Glass
Authors: COLE SANDFORD S.
Published: June 2006

Sintering of an 80% Ag‐20% Pd powder in the absence of a liquid phase below 750°C proceeds according to a grain‐boundary diffusion model. The same powder was sintered with a glass which exhibited incomplete wetting. By comparing sintering rates, the occurrence of solution‐precipitation sintering in the glass‐bearing system was established. The data for the two systems are best compared by using expressions which allow fired size, L, to be plotted vs time to the nth power.
Estimate of Enthalpies of Formation and Fusion of Cordierite
Authors: NAVROTSKY A. , KLEPPA O. J.
Published: June 2006

The enthalpies of solution in molten 2PbO·B2O3 at 690°±2°C of cordierite, Mg2Al4Si5O18, and of a glass of cordierite composition were determined. From these data, the enthalpy of formation of cordierite from the component oxides is ‐16.1±1.7 kcal/mol and its heat of fusion +54.0±2.0 kcal/mol.
Neutron Activation of Masked Samples
Authors: VARSHNEYA A. K. , COOPER A. R. , DIEGLE R. B. , CHIN S. A.
Published: June 2006

A nonuniform distribution of a radioactive tracer was produced within a glass specimen by partially masking it with Cd and irradiating it with thermal neutrons. The calculated distribution of the tracer in the given geometry agreed reasonably well with the measured distribution. The latter, in turn, served as the initial condition for a self‐diffusion experiment which gave results consistent with previous studies. This technique avoids problems associated with interfaces in conventional diffusion couples.
Errors Associated with Temperature Measurements in Hot Glass
Authors: GLICKSMAN LEON R. , RENIER G.
Published: June 2006

The errors associated with temperature measurement in glass by thermocouples and optical means are examined. Thermocouple measurements will have significant errors when the thermocouple is placed near a bounding surface or in glass which has a significant temperature gradient. In the spectral scanning technique, spectral measurements at various wavelengths are used to infer the temperature distribution through the glass. Errors in spectral measurements are strongly magnified in the solution for the temperature profile; mathematical smoothing tends to reduce the error. Absorption techniques can be used to measure glass temperature accurately in certain circumstances.
Effect of Phase Separation on Helium Migration in Sodium Silicate Glasses
Authors: SHELBY J. E.
Published: June 2006

Helium permeability, diffusion, and solubility were measured in sodium silicate glasses containing 0 to 40 mol% Na2O. These properties appear to depend on the substructure of the glass, since definite inflections occur in the curves of diffusivity and solubility vs composition at the boundaries of the two‐phase region. Similar inflections occur for the activation energy for diffusion and enthalpy of solution at the phase boundaries. These effects are explained by use of a two‐component diffusion model within the miscibility gap and a one‐component model in the single‐phase region.
Properties and Structure of Glasses in the Systems M2O‐In2O3‐GeO2 (M = Li,Na,K)
Authors: FAIRWEATHER M. J. , MURTHY M. K.
Published: June 2006

The glass‐forming regions in the ternary systems M2O‐In2O3‐GeO2 (M = Li,Na,K) were determined. The region in each of the three ternaries is less extensive than in either of the analogous systems M2O‐Al2O3‐GeO2 and M2O‐Ga2O3‐GeO2; this behavior reflects the restrictive coordination requirements of the larger In ion. The In2O3‐containing glasses exhibit higher densities and refractive indices than the corresponding Al2O3 and Ga2O3‐containing glasses. Refractive index and density maxima are observed along lines of constant In2O3 in each of the three alkali indogermanate systems.
Equilibrium Oxygen Potential‐Composition Relations in U0.75Pu0.25O2‐x
Authors: WOODLEY R. E.
Published: June 2006

Variations in the composition of U0.75Pu0.25O2‐x as a function of the oxygen potential were determined by a thermogravimetric technique over the interval 950° to 1400°C. Oxygen potentials ranging from ‐100 to ‐155 kcal/mol were established by means of H2O‐H2‐O2 equilibria. The partial molar enthalpy and entropy of solution of O2 in the mixed oxide fuel were independent of temperature over the interval investigated but varied with the composition of the fuel.
Radiation‐Induced Creep of UO2
Authors: SOLOMON A. A.
Published: June 2006

In‐reactor creep tests were performed on stoichiometric UO2 helices enriched with 1.82%235U at fission rates of 2×1012 to 1.5×1013 fissions/cm3‐s and outer‐fiber shear stresses of 2890 and 2090 psi. Depending on the test procedure, the initial creep transient either decelerated continuously or was of the sigmoidal type; this difference is rationalized in terms of the radiation‐produced substructure. For constant substructure, however, strain rate was linearly proportional to fission rate. Strain recovery was also observed when the specimens were unloaded and then irradiated. Postirradiation creep tests conducted at zero fission rate showed that fission events are required for either creep or strain recovery to occur. Incremental‐temperature‐change experiments and normalized strain‐rate‐vs‐temperature plots verified that the deformation was athermal at T≤200°C. Postirradiation examination showed that 0.01% strain was recovered after a specimen was fractured and irradiated, but no measurable swelling, changes in density, grain size, or stoichiometry had occurred. No evidence of microfracture was observed on ceramographic sections. A model for radiation‐induced creep is proposed in which Frank loops and dislocations absorb interstitials produced locally by the fission spike and move with the aid of the localized thermal energy of the spike.
Holographic Storage in Quadratic PLZT Ceramics
Authors: MICHERON F. , MAYEUX C. , HERMOSIN A. , NICOLAS J.
Published: June 2006

Photoinduced changes in refractive index in a quadratic electrooptic PLZT ceramic were observed. Thick‐phase holograms were recorded with high diffraction efficiency (η∼ 0.10 to 0.50). The dependencies of the diffraction efficiency on the density of light energy and applied field were determined. The observed amplification effect is explained in terms of photoinduced electrical field components and the quadratic electrooptic properties of the ceramic.
Simplified Mathematical Model Simulating Heat Transfer in Glass‐Forming Molds
Authors: MANTHURUTHIL J. , SIKRI T. R. , SIMMONS G. A.
Published: June 2006

Heat transfer in glass‐forming operations depends on many factors, e.g. the properties of the glass, heat‐transfer coefficients at the glass/mold and mold/air interfaces, the characteristics of the mold material, and the glass/mold contact time. Using a computer model developed for one‐dimensional heat flow, the influences of these factors were calculated. The heat‐transfer parameters, which were analyzed individually, include e.g. the glass surface temperature, the peak inner mold surface temperature, the quantity of heat transferred from glass to mold during a steady‐state cycle, and the amplitude of mold surface temperature oscillation at steady state. Comments are given on the significance of the results.
Use of Stabilized ZrO2 to Measure O2 Permeation
Authors: KITAZAWA K. , COBLE R. L.
Published: June 2006

The rate of permeation of CaO‐stabilized ZrO2 (CSZ) by O2 gas was measured from 640° to 1200°C with the CSZ tubing used simultaneously as the sample and the O2 pressure detector. The apparent permeation rate depended significantly on the O2 pressure at the low‐pressure side. The rate measured by this method was orders of magnitude smaller than that measured under steady‐state conditions, except when the O2 partial pressure was high (>10−4 atm), in which case the agreement was good. The difference between steady‐state permeability and non‐steady‐state permeability is related to the deviation in stoichiometry in a sample or detector. The transient response (measured under variable pressure difference) may be very different from steady‐state permeation (measured under constant differential pressures across the membranes). To apply CSZ to typical O2 gas permeability measurements, the O2 pressure must be kept above ∼ 10−3.5 atm. In this range, the permeability of CSZ may be regarded as a temperature‐dependent material property which is governed by the electron‐hole mobility. At lower O2 pressures the permeation rate is a more complex function of the pressure difference and level.
Compound Formation and Phase Equilibria in the System PbO‐SiO2
Authors: SMART R. M. , GLASSER F. P.
Published: June 2006

Compound formation in the system PbO‐SiO2 was studied; the results are contrasted with those previously reported. Fifteen binary phases, 4 of which had not been reported, were prepared in the present study. The new phases include Pb5Si8O21, an orthorhombic polymorph of PbSiO3, Pb3SiO5, and a high‐SiO2 phase containing ∼ 60 mol% SiO2. It was shown that Pb3SiO5 is thermodynamically stable relative to Pb2SiO4 and 4PbO.SiO2 below 640±5°C. A revised phase equilibrium diagram is presented.
Use of Fracture Mirrors to Interpret Impact Fractures in Brittle Materials
Authors: KIRCHNER H. P. , GRUVER R. M. , SOTTER W. A.
Published: June 2006

The impact resistances and fracture mirror radii (rm) of rods of several ceramic materials were measured. The fracture stresses (σf) were determined from σfvs rm−1/2curves obtained from fiexural strength tests. An analysis, based on the assumption that the principal factor contributing to the impact energy absorbed is the energy (Ue) required to deflect the specimen to the fracture stress, indicated that the impact energy absorbed (U) per unit of specimen cross‐sectional area (A) increased in proportion to the square of the maximum stress. The analysis also indicated that the slopes of the curves ofU/Avs σf2are proportional to the reciprocal of Young's modulus. Experimental data for several materials are consistent with this analysis.
Concentration and Temperature Dependence of Diffusion and Conductance in Molten BeF2‐LiF Mixtures
Authors: VALLET C. E. , BRAUNSTEIN J.
Published: June 2006

Electromigrational depletion chronopotentiometry was used to study interdiffusion in molten BeF2‐LiF mixtures (78 to 98 mol% BeF2). The concentration and temperature dependencies of electrical conductance and interdiffusion were derived for 78 to 98 mol% BeF2 and 570° to 700°C. The Arrhenius energies are compared with those for viscous flow in the BeF2‐LiF system and in structurally related silicate systems.
Grain Boundary Phases in a Hot‐Pressed MgO Fluxed Silicon Nitride
Authors: CLARKE D. R. , THOMAS G.
Published: June 2006

Although high‐temperature strength loss in ceramics such as silicon nitride has been attributed to the presence of intergranular amorphous phases, until now no direct proof has been offered. The present paper describes high resolution electron microscopy lattice imaging studies of an MgO fluxed hot‐pressed silicon nitride. These studies indicate that intergranular second phases do indeed exist, but they are heterogeneously distributed, appearing especially at multiple grain junctions. These room temperature observations are compatible with the microstructures expected at elevated temperatures.
Slow Crack Growth from Controlled Surface Flaws in Hot‐Pressed Si3N4
Authors: MENDIRATTA M. G. , PETROVIC J. J.
Published: June 2006

The elevated‐temperature slow‐crack‐growth behavior of HS‐130 Si3N4 was studied by extending “controlled” surface cracks in bars loaded in 4‐point bending. Several such nonin‐teracting cracks were produced on the tensile surfaces of bend bars by Knoop microhardness indentation. The stress and dimensions of the subcritically growing cracks were used to calculate the stress‐intensity factor, K1, from fracture‐mechanics formulas for semielliptical surface cracks in bending. The crack‐growth velocity, v, was obtained by dividing crack extension by loading time interval. The data indicated very large scatter in measured velocities for given K1 values, which was interpreted as due to the interaction of the small cracks with local material heterogeneities. No simple functional relation between K I and v could be established for HS‐130 Si3N 4 from the v−K1 data.
Theory of the Narrow Sandwich Seal
Authors: GULATI S. T. , HAGY H. E.
Published: June 2006

An approximate theoretical treatment of the narrow sandwich seal provides the necessary correction factor for calculating true thermal expansion mismatch between seal members from the observed birefringence. The shape factor, which physically represents the extent to which the Poisson strain is developed in the narrow direction, is a strong function of the aspect ratio (width/thickness) of the core member. Its value is 0 to 1 for aspect ratios of 0 to >20. The effect of the thickness ratio (of the seal members) and elastic moduli on the shape factor is relatively small. It is found that large errors can arise in the calculated value of the thermal expansion differential if the shape factor is not taken into account.
Impurity‐Induced Exaggerated Grain Growth in Mn‐Zn Ferrites
Authors: YAN M. F. , JOHNSON D. W.
Published: June 2006

The effects of 20 oxide dopants on the microstructure development of Mn‐Zn ferrite during sintering were investigated by diffusion‐couple‐like experiments. Nine oxides enhanced grain growth in ferrite; the effects of TiO2 dopant were studied in detail. The TiO2‐induced exaggerated grain growth shows a parabolic time dependence, as was also true for the diffusion of Ti into ferrite as shown by X‐ray spectrometry. For samples sintered at a given temperature but for different times, the Ti concentrations at the growth fronts of the exaggerated grains are identical. Exaggerated grain growth kinetics and Ti diffusivities have similar activation energies. Furthermore, the mobility of the exaggerated grains is reduced to that of the matrix grains after the TiO2 layer is removed, showing that the exaggerated grain growth is sustained by Ti diffusion into ferrite. Probable mechanisms for TiO2‐promoted exaggerated grain growth are proposed. Some self‐consistent arguments are presented for the observed effects of other dopants. Grain boundary mobilities of undoped Mn‐Zn ferrite were measured and are in good agreement with those reported in the literature.
Grain‐Size Dependence of Spontaneous Cracking in Ceramics
Authors: RICE R. W. , POHANKA R. C.
Published: June 2006

Models based on energy and stress considerations are applied to the phenomenon of spontaneous fracture of materials due to phase transformations and thermal expansion anisotropy. Results are shown to be in reasonable agreement with observations of the grain‐size dependence of such cracking and the effects of internal stresses on strength. The occurrence and effects of sequential cracking in highly anisotropic materials are considered. Effects of the degree of anisotropy, twinning, porosity, and second phases on such cracking are noted.
Stability of the β″‐Alumina Phase in the System Na‐Al‐Fe‐O
Authors: ROLAND J. P. , TSENG T. Y. , VEST R. W.
Published: June 2006

X‐ray diffraction measurements were used to determine the equilibrium phases for Na2O·y(Al1‐xFex)2O3_m in air for values of x from 0.05 to 0.6 and values of y from 2.5 to 9. The β“ ‐alumina structure was the only single phase observed. At 1400°C, the β” single‐phase region extends for 3.5< y< 7.5 and 0.2< x< 0.55. Precision lattice parameters were determined as functions of x and y.
Density Profile of Small Glass Drops Chilled from the Liquid State and Subsequently Thermally Treated
Authors: TONINATO T. , COGONI G. , GOTTARDP V. , SCARINCI G.
Published: June 2006

The density profile was determined, from the surface to the core, of small soda‐lime glass drops obtained by quenching in water from the liquid state. It was shown that, initially, the density increases from the surface to the inner layers but this trend is reversed at a certain distance from the surface, so that the density values found in the innermost layers are unusually low. Other investigations confirmed the existence of structural situations in the core different from those at the surface of each sphere. The quenched spheres were then heated at different temperatures for different times and the densities of the various layers were measured to determine the response of each zone to heat treatment after quenching. Some hypotheses are proposed to explain the results.
Microstructure of a 12H Mg‐Si‐Al‐O‐N Polytype Alloy: Intergranular Phases and Compositional Variations
Authors: CLARKE D. R.
Published: June 2006

The mil‐restructure of a 12H polytype alloy having a composition Mg, 86A1,67Si2.47O3.19N3.81 was examined by transmission electron microscopy with the techniques of X‐ray spectroscopy microanalysis and lattice fringe imaging. An intergranular film (2.5 to 10 nm thick) is present at the majority of two‐grain junctions. At several boundaries, the polytype fringe spacing decreases abruptly near the boundary, indicating a change in poiytype structure and composition. The intergranular phase at three‐grain junctions is partially crystallized and the crystalline regions incorporate principally Mg and Si cations, whereas the surrounding amorphous phase contains Si, Mg, Ca, and Al cations. The composition of one of the glassy regions is calculated as about Mg2.5Si0.42Al0.13Ca0.95(ON).
Combining Data for Improved Weibull Parameter Estimation
Authors: BATDORF S. B. , SINES G.
Published: June 2006

Weibull parameters are often used by experimentalists to characterize the fracture behavior of structural materials. Frequently, several types of tests are performed, and theory indicates that the parameters for each type should be the same or have some specific relation to each other. In such cases, it is advantageous to combine the data to find the parameters best representing all the data. The present paper discusses techniques for carrying out this objective and analyzes two examples in detail to illustrate the principles involved. The first example compares uniaxial and equibiaxial fracture statistics and the second discusses fracture statistics for single fibers of several lengths.
Effect of Thermal Expansion Mismatch on the Thermal Diffusivity of Glass‐Ni Composites
Authors: POWELL BOB R. , YOUNGBLOOD G. E. , HASSELMAN D. P. H. , BENTSEN LARRY D.
Published: June 2006

The effect of interfacial decohesion, due to the thermal expansion mismatch, on the thermal diffusivity of a hot‐pressed glass matrix with a dispersed phase of nickel was investigated by the laser‐flash technique at 25° to 600°C. The interfacial gap formed on cooling acts as a barrier to heat flow and lowers the thermal diffusivity to values below those predicted from composite theory and also creates a strongly positive temperature dependence of the thermdl diffusivity. Preoxidation of the Ni spheres promotes interfacial bonding and yields values of thermal diffusivity higher than those for nonoxidized spheres and a thermal diffusivity which is relatively temperature‐independent. The results of the present study also confirm the criteria for the effective thermal diffusivity of composites established by Lee and Taylor.
Improved Impact Resistance in Soda‐Lime‐Silica Glasses Through Zinc Oxide Substitutions
Authors: MCCAULEY Ronald A. , DE Asok K. , CARR Dodd S.
Published: June 2006

Several soda‐lime‐silica glasses were melted in which up to 8.52 wt% zinc oxide was substituted for calcium and magnesium oxide. Sonic Young's modulus and Charpy impact resistance measurements were made. The results indicated that an increase of 8.52 wt % zinc oxide reduced the Young's modulus by 9.0% and increased the impact resistance of the soda‐lime‐silica glass by 4.1%.
Dielectric Relaxation Strength of a Low‐Alkali Glass
Authors: CORDARO J. F. , TOMOZAWA MINORU
Published: June 2006

The low‐frequency dielectric loss maxima for glasses with low alkali concentrations are often obscured by a much larger dc conductivity contribution to the dielectric loss. Therefore, quantitative determination of the dielectric relaxation strengths for these glasses is difficult. An approximate relation between the impedance, electric modulus, and dielectric constant relaxation maxima is developed for glasses exhibiting small dielectric relaxation strengths. Using the obtained relations, the dielectric relaxation strength, Δe, for a GeO2 glass containing 47 wt ppm Na2O is estimated to be ≅0.3.
Deuterium Treatment and Infrared Transmission Spectra of Fused Silica
Authors: Kumar Binod , Fernelius N. , Detrio J. A.
Published: June 2006

The effects of deuterium treatment on the in absorption bands infused silica were measured. The deuterium treatment progressively replaces the OH group by the OD group as determined by reduction in the intensity of OH bands. New OD bands of lower intensity were developed at longer wavelengths. The extinction coefficient of the OD group was determined to be 0.57 times lower than that of the OH group.
Systemic disease among cases of fatal opioid toxicity
Authors: Darke Shane , Kaye Sharlene , Duflou Johan
Published: June 2006

Aims To determine levels of systemic disease among cases of death due to opioid toxicity.

Design Analysis of coronial cases.

Setting Sydney, Australia.

Cases A total of 841 cases of death due to opioid toxicity (1 January 1998–31 December 2002).

Findings Ventricular hypertrophy was present in 5.9% of cases and severe coronary artery atherosclerosis in 5.7%. Severe coronary pathology was more pronounced among older cases. Pre‐existing bronchopneumonia was present in 13.2% of cases. Hepatic pathology was the most common type of pathology, and was far more marked among older cases. Cirrhosis was present in 25.3% of those aged > 44 years. Levels of renal pathology were comparatively low, but were related significantly to increasing age. Systemic disease in more than one organ system was present in 24.4% of cases, and was related to increasing age (44% of those aged > 44 years). The only pathology for which gender was an independent predictor among opioid cases was ventricular hypertrophy, more common in males.

Conclusions Systemic disease, most prominently liver disease, is common among fatal opioid toxicity cases, and may be a factor in understanding the dynamics and age demographics of opioid‐related death.
Alloimmunization among patients with transfusion‐dependent thalassemia in Taiwan
Authors: Wang L.‐Y. , Liang D.‐C. , Liu H.‐C. , Chang F.‐C. , Wang C.‐L. , Chan Y.‐S. , Lin M.
Published: June 2006

summary.  The development of erythrocyte alloantibodies complicates transfusion therapy in patients with thalassemia. However, no data are available on the frequency of erythrocyte alloimmunization in patients with transfusion‐dependent thalassemia in Taiwan. We analysed the clinical and transfusion records of 30 individuals (15 females and 15 males; mean age, 20 years; range, 4–31 years) with thalassemia who had regular transfusions for periods ranging from 0·5 to 20 years. Of the 30 patients, 28 who had β‐thalassemia major and two who had Hb H disease (α thalassemia), 11 (37%) were found to carry alloantibodies. All alloantibodies were clinically significant specificities, including four cases of anti‐E, two of anti‐E + c, two of anti‐‘Mia’, one of anti‐‘Mia’ + E, one of anti‐D and one of anti‐S. Alloimmunization to erythrocyte antigens is a frequent complication in transfusion‐dependent thalassemia.
Plica neuropathica in a 2‐year‐old boy
Authors: Kanwar Amrinder J. , De Dipankar
Published: June 2006

Plica neuropathica is a rare acquired condition of sudden onset characterized by irreversible tangling of hair. It is sparsely reported in the literature, though it does not seem to be uncommon, at least in Hindu‐religious persons of India. However, it has not been previously reported in patients as young as 2 years of age, and consequently this fact warranted reporting.