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Effect of Moisture on the Thermal Protective Performance of Heat-Resistant Fabrics

The effect of fabric moisture on thermal insulation properties of twelve heat resistant fabrics made with polybenzimidazole (PBI), aromatic polyamide (aramid) and blends of PBI with aramid or with flame retardant rayon fibers is investigated in several high intensity radiant and convective heat exposures. Three fabric…

The engineering geology of clay minerals: swelling, shrinking and mudrock breakdown

Abstract Swelling, shrinking and physical breakdown processes are reviewed with reference to well-known mudrock and overconsolidated clay formations in the UK and USA. Swelling results from two processes: the equilibration of depressed porewater pressures following stress relief, and the physico-chemical (osmotic) res…

Grain‐Boundary Effect in Ceria Doped with Trivalent Cations: I, Electrical Measurements

The “grain‐boundary effect,” which leads to a greatly reduced dc ionic conductivity due to the presence of a blocking layer in the vicinity of the grain boundaries, is studied in detail for ceria ceramics doped with various trivalent dopants (particularly Y 3+ , Gd 3+ , and La 3+ ). The effects of porosity, of sinteri…

Standard X-Ray Diffraction Powder Patterns from The JCPDS Research Associateship

The following new or updated patterns are submitted by the JCPDS Research Associateship at the National Bureau of Standards. The patterns are a continuation of the series of standard X-ray diffraction powder patterns published previously in the NBS Circular 539, the NBS Monograph 25, and in this journal. The methods o…

Compound materials for reversible, phase-change optical data storage

Results of rapid (laser induced) and slow (heating stage induced) crystallization studies on Te1−xGex, 0≤x≤0.6, are reported. The time it takes to laser crystallize varies with x by more than four orders of magnitude. Films with stoichiometric compositions, Te and GeTe, can be crystallized using laser pulses of less t…

Oxidation Kinetics of Silicon Carbide Crystals and Ceramics: I, In Dry Oxygen

The oxidation kinetics of several single‐crystal and polvcrystalline silicon carbide materials and single‐crystal silicon in dry oxygen over the temperature range 1200° to 1500°C were fitted to the linear‐parabolic model of Deal and Grove. The lower oxidation rates of silicon carbide compared to silicon can be rationa…

Phonons, phasons, and dislocations in quasicrystals

In this paper we examine the detailed relationship between the density-wave and unit-cell descriptions of quasicrystals. We show that phonons, phasons, and dislocations correspond to translations, distortions, and rearrangements of unit cells. The associated density-wave images closely resemble experimental electron m…

Theory of lyotropic polymer liquid crystals

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTheory of lyotropic polymer liquid crystalsTheo OdijkCite this: Macromolecules 1986, 19, 9, 2313–2329Publication Date (Print):September 1, 1986Publication History Published online1 May 2002Published inissue 1 September 1986https://pubs.acs.org/doi/10.1021/ma00163a001https://…

Zero-dimensional "excitons" in semiconductor clusters

Semiconductor crystallites of characteristic dimension\sim20-100Å can be made by precipitation in liquids and dielectrics. These crystallites have bulk-like internal lattices. The optical spectra show partially resolved discrete features that result from carrier spatial confinement in three dimensions. Spectral shifts…

Transient cavities near boundaries. Part 1. Rigid boundary

The growth and collapse of transient vapour cavities near a rigid boundary in the presence of buoyancy forces and an incident stagnation-point flow are modelled via a boundary-integral method. Bubble shapes, particle pathlines and pressure contours are used to illustrate the results of the numerical solutions. Migrati…

CrO2predicted as a half-metallic ferromagnet

The band structure of chromium dioxide, which is an important material because of its magnetic properties, has been calculated with the augmented spherical wave method by performing self-consistent spin-polarised calculations. The majority-spin electrons are metallic, whereas the minority-spin electrons are semiconduc…

Dendritic macromolecules: synthesis of starburst dendrimers

ADVERTISEMENT RETURN TO ISSUEPREVArticleDendritic macromolecules: synthesis of starburst dendrimersDonald A. Tomalia, H. Baker, J. Dewald, M. Hall, G. Kallos, S. Martin, J. Roeck, J. Ryder, and P. SmithCite this: Macromolecules 1986, 19, 9, 2466–2468Publication Date (Print):September 1, 1986Publication History Publish…

Crystalline syndiotactic polystyrene

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCrystalline syndiotactic polystyreneN. Ishihara, T. Seimiya, M. Kuramoto, and M. UoiCite this: Macromolecules 1986, 19, 9, 2464–2465Publication Date (Print):September 1, 1986Publication History Published online1 May 2002Published inissue 1 September 1986https://pubs.acs.org/…

Mathematical models of hysteresis

A new approach to the scalar Preisach model of hysteresis, which emphasizes its phenomenological nature and mathematical generality, is described. The theorem, which gives the necessary and sufficient conditions for the representation of actual hysteresis nonlinearities by the scalar Preisach model, is reported. The s…

Modified Starches Properties and Uses

SECTION I: MODIFIED STARCHES-THEIR CHEMISTRY AND PROPERTIES. Converted Starches. Cross-Linked Starches. Acetylated Starch and Miscellaneous Organic Esters. Hydrox-yethylated Starches. Hydroxypropylated Starches. Phosphory-lated Starches and Miscellaneous Inorganic Esters. Cationic Starches. Succinate and Substituted S…

EPR and thermoluminescence studies in RT X-irradiated CaO single crystals

Thermoluminescence and EPR measurements in RT X-irradiated CaO are reported. Two glow peaks at 360 and 400K are associated with the thermal destruction of two new donor-type paramagnetic defects of extrinsic character. The EPR spectrum of the defect that produces the first glow peak consists of an intense central line…

Computer simulation studies of cation migration mechanisms in sodium beta-alumina

The authors report the results of a molecular dynamics (MD) simulation of stoichiometric (S) and non-stoichiometric (NS) sodium beta -Al 2 O 3 . Results confirm the hopping diffusion up to 1000K governed by the flatness of the sodium-ion potential surface in the conduction plane. A detailed analysis of the Na + -ion d…

Multicriticality in Hexatic Liquid Crystals

A theory is presented for the successive sixfold Fourier components, ${C}_{6n}$, in the bondorientational order in the neighborhood of a $\mathrm{s}\mathrm{m}\mathrm{e}\mathrm{c}\mathrm{t}\mathrm{i}\mathrm{c}\ensuremath{-}A\ensuremath{-}\mathrm{h}\mathrm{e}\mathrm{x}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{c}\ensuremath{…

Development and origin of conical structures on XeCl laser ablated polyimide

Stable, well-defined conical structures have been observed to develop on the surface of excimer laser etched polyimide. Deliberate seeding shows that these are induced by the shielding effect of particulate impurities and indicates means for controlling the surface microstructure.