A simple high-temperature infrared cell and its application to the dehydroxylation of kaolinite

A simple method is described for making infrared measurements on solids at temperatures up to the melting point of KBr by using a fine nichrome heating coil wound directly on to the KBr disc containing the sample either in suspension or sedimented on to the surface. The usefulness of the method is illustrated by intensity measurements of the hydroxyl stretching bands in kaolinite as a function of temperature, which are compared with results obtained by the more conventional quenching method.     

Pseudotumour of the lung caused by infection with Bacillus sphaericus

A patient is described who suffered from severe chronic asthma complicated by repeated chest infections. She developed a large gelatinous pseudotumour of the lung which was found to be caused by Bacillus sphaericus.     

Mechanical properties of selected glasscrystal composites

Desirable physical properties not provided by single-phase materials are often conveniently attained by multiphase composites. This paper is concerned with the variation of the mechanical properties of bulk glass through the incorporation of a crystalline oxide phase. Glass-Al₂O₃ and glass-ZrO₂ composites containing 20 and 40 vol % spherical, crystalline inclusions, 125 to 150 rn in diameter, were prepared by hot pressing. The effects of internal stress and elastic properties of the crystalline inclusion on composite mechanical properties were studied. Experimental elastic-property values agreed well with theoretical values calculated from Hashin's equations. Flexural strength tests of all composite compositions revealed that the fracture path rarely traversed the crystalline oxide inclusions. The Al₂O₃ and ZrO₂ additions strengthened the glass considerably, except when internal stresses were of sufficient magnitude to cause cracking of the glassy matrix upon cooling and before flexural testing. Glass-Al₂O₃ composites were consistently stronger than the glass-ZrO₂ counterparts. This strength difference is attributed to the higher elastic moduli of the Al₂O₃ composites. Hypotheses which postulate strengthening as a result of restricted flaw size are apparently not applicable to these materials.This paper is based on part of a thesis submitted by W. J. Frey in partial fulfilment of the requirements for the degree of Master of Science in Materials, Rensselaer Polytechnic Institute, June 1966.     

Measuring the strength, structure, and reliability of free associations.

Criticizes current associative measures of word relatedness for being insufficiently versatile and for having inadequate statistical justification. This criticism is extended to a widely used measure, the mutual frequency score, which has been held to be based on the product-moment correlation. Measures of the reliability of free association are criticized on a similar basis. The reliability of free associations has typically been measured as the tendency of Ss to respond consistently on retesting. It is argued that the stability of the distribution of associations to a given stimulus, regardless of the behavior of individual Ss, is of greater interest and application. An association measure based on the product-moment correlation, and appropriate for measuring both word relatedness and the reliability of associations, is described. The prediction of free recall and the measurement of reliability in a study with 283 undergraduates is summarized. (34 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Composition and crystal structure of resorbable calcium phosphate thin films

Silicon stabilized tricalcium phosphate (Si-TCP) is formed, among other phases, as a result of sintering hydroxyapatite (HA) in the presence of silica (SiO₂) at >800°C. Calcium phosphate films sintered at 1000°C on quartz substrates are examined with and without additional SiO₂ added to the starting precipitate. Data from transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) separate the undoped film morphology into a surface layer with a monoclinic crystal structure P2₁/a characteristic of α or Si-tricalcium phosphate and grain size in the range 100–1000 nm and a substrate layer with a crystal structure which is predominantly apatitic P6₃/m and grain size in the range 30–100 nm. The silicon content is greatest in the substrate layer. The addition of SiO₂ to the film material during fabrication induces a more uniform grain size of 10–110 nm and a higher Si content. The structural and phase evolution of these films suggests the nucleation of α-TCP by the local formation of Si-TCP at a SiO₂-hydroxyapatite interface. The results are consistent with X-ray diffraction studies and are explained by a model of nucleation and growth developed for bulk powders.     

Variable thermochemical stability of RE2Si2O7 (RE = Sc,Nd, Er,Yb, or Lu) in high-temperature high-velocity steam

Five rare-earth (RE) disilicates (RE₂Si₂O₇, RE = Sc, Nd, Er, Yb, or Lu) were synthesized and exposed to high-velocity steam (up to 235 m/s) for 125 hours at 1400°C. Water vapor reaction products, mass loss, average reaction depths, and product phase microstructural evolution were analyzed for each material after exposure. Similar to steam testing results in the literature, RE₂Si₂O₇ (RE = Er, Yb, Lu) underwent silica depletion producing gaseous silicon hydroxide species, RE₂SiO₅, and RE₂O₃ product phases. Sc₂Si₂O₇ reacted with high-velocity steam to produce only a Sc₂O₃ product layer with no stable Sc₂SiO₅ phase detected by X-ray diffraction or microscopy techniques. Further, Nd₂Si₂O₇ rapidly reacted with steam to produce with no Nd₂SiO₅ or Nd₂O₃ reaction products. All RE₂Si₂O₇ that produced a silicate reaction product (RE = Nd, Er, Yb, Lu) showed densification of the product phase at steam velocities above 150 m/s that resulted in enhanced resistance. The results presented in this work demonstrate that rare-earth silicates show diverse steam reaction products, reaction product microstructures, and total reaction depths after high-temperature high-velocity steam exposure. Of the materials in this study, RE₂Si₂O₇ (RE = Yb, Lu) were most stable in high-temperature high-velocity steam, making them most desirable as environmental barrier coating candidates.     

Shakedown and limit analysis of 90° pipe bends under internal pressure,cyclic in-plane bending and cyclic thermal loading

The Linear Matching Method is used to create the shakedown limit and limit load interaction curves of 90° pipe bends for a range of bend factors. Two load cases are considered i) internal pressure and in-plane bending (which includes opening, closing and reversed bending) and ii) internal pressure and a cyclic through wall temperature difference giving rise to thermal stresses. The effects of the ratios of bend radius to pipe mean radius (R/r) and mean radius to wall thickness (r/t) on the limit load and shakedown behaviour are presented.     

Physical Properties of Co-crystalline Sugar and Honey

ABSTRACT: Clear and partially granulated honeys, were co-crystallized with sucrose in 3 proportions, 90:10, 85:15, 80:20, respectively. The products obtained by centrifugal filtration from both honeys were found by high-performance liquid chromatography to contain between 1% and 2% of honey. The moisture content of the products increased with the amount of honey added, whereas their powder flowability decreased. Differential scanning calorimetry showed a decrease in the overall crystallinity of the solidified products with an increase in the amount of honey added. Neither crystalline fructose nor glucose was detected by powder X-ray diffraction in any of the co-crystalline products. Glucose monohydrate crystallized on storage in some co-crystalline materials prepared from granulated honey.     

The effect of nano sized SrFe<Subscript>12</Subscript>O<Subscript>19</Subscript> additions on the magnetic properties of chromium-doped strontium-hexaferrite ceramics

Strontium hexaferrite (SrFe₁₂O₁₉) which crystallizes in the hexagonal system and has a uniaxial magnetoplumbite structure, displays distinctive magnetic characteristics, good chemical stability, good tribological properties and a weak temperature dependent coercivity at about room temperature. In the present work the synthesis conditions for the solid-state preparation of the chromium-doped hexaferrite SrCr_0.3Fe_11.7O₁₉ were optimised and the effect on the magnetic properties of this compound of additions of nanosized SrFe₁₂O₁₉ was studied. The nanosized SrFe₁₂O₁₉ additive, synthesized by the citrate–nitrate reaction, was substituted in varying amounts for a commercial calcium silicate borate sintering additive mixture. A combination of 0.75 wt% of nano-sized SrFe₁₂O₁₉ with 0.75 wt% of the commercial additive increases the intrinsic coercivity, remanence magnetization and rectangularity ratio and results in superior magnetic properties than obtained with 1.5 wt% of nanosized SrFe₁₂O₁₉ or the commercial sintering additive alone.