Materials Literature
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Ultradrawing of atactic poly(acrylonitrile) (PAN) was investigated for a Mv series, ranging 8.0 × 104–2.3 × 106. Samples for the draw were prepared from 0.5–30 wt % solutions of PAN in N,N′-dimethylformamide. The solutions were converted to a gel by quenching from 100 to 0°C. The dried gel films were initially drawn u…
Metastable alumina phases developed in plasma sprayed alumina were studied by both electron diffraction and high-resolution transmission electron microscopy. A new alumina polymorph with monoclinic symmetry, denoted θ″-Al2O3, was identified. The crystal structure of θ″-Al2O3 was described by the A12/n1 space group and…
Abstract The structure of a cubic Al 67.4 Pd 11.4 Mn 14.4 Si 6.8 phase, which is referred as an 1/1 rational approximant of an icosahedral phase, was determined by means of single crystal X-ray structural analysis: space group Pm 3 (No. 200), a = 12.281(1) Å, V = 1852.0(3) Å 3 , Mo K α ( λ = 0.71069 Å); refined as Al…
A new technique for nanometer-scale gap formation was proposed and investigated for the possibility in vacuum microelectronic device application. When the temperature is down at the end of oxidation, the compressive stress induced at the initially connected slim polysilicon patterns forces to be separated into two par…
Crystalline and amorphous thin films of tungsten(VI) oxide can be prepared by chemical vapor deposition using a variety of volatile precursors below 500 °C. Deposition parameters for preparation of WO3 films from tungsten hexacarbonyl [W(CO)6], tungsten hexafluoride (WF6), tungsten ethoxides [W(OEt)x, x = 5, 6] and te…
Summary The analysis of X‐ray diffraction (XRD) patterns by the Rietveld method was tested for characterizing quantitatively the mineralogical composition of a ferralitic soil from southern Mali. Quantitative analysis of two samples from this soil revealed kaolinite and quartz as major components and smaller amounts o…
The oxidation of Nicalon fibers is a concern, because of its potential as a reinforcement of high‐temperature composites, whose service conditions involve high‐temperature, oxidizing environments. Two limiting types of oxidation mechanisms are often used to describe the kinetics: chemical‐reaction‐controlled oxidation…
A special test fixture has been developed for fracture mechanical testing of brittle materials inside an environmental scanning electron microscope. The fixture loads a double cantilever beam specimen with pure bending moments and provides stable crack growth. Crack growth is detected by in situ observation and acoust…
In the far anodic regime, the anodic dissolution of silicon exhibits a resonant behavior, which results from an oscillating behavior on the microscopic scale. The interface has been investigated using in situ infrared spectroscopy in the strong oscillating regime. The interface oxide film varies in thickness by up to…
Abstract The effects of heating and cooling rates on the structure of N660 and N299 carbon black particles have been investigated using Raman spectroscopy, X-ray scattering, and the BET technique. Carbon blacks were kept at 2700 K for various lengths of time and next cooled down at different rates. The size of crystal…
The paper describes an evaluation of kinetic parameters for sintering from the analysis of stepwise isothermal dilatometry data for the pore‐forming process of macroporous alpha‐Al 2 O 3 ceramics fabricated by extrusion. The experimental results demonstrated that isothermal shrinkage data for the sintering process can…
The mechanism of heat aggregation of proteins proposed by the author involves the stage of irreversible denaturation, the stage of nucleation, and the stage of growth of aggregates. It was shown that the initial parts of the kinetic curves of aggregation followed by monitoring the increase in absorbance (A) or intensi…
Hi‐Nicalon/SiC minicomposite specimens containing three oxide interphase layers (amorphous SiO 2 , monoclinic ZrO 2 , and amorphous SiO 2 ) were prepared by chemical vapor deposition. The minicomposites exhibited graceful composite failure behavior with reasonable load‐carrying capability in room‐temperature tensile t…
Ellipsometric studies are generally carried out in the reflection mode rather than in the transmission mode, requiring invariably opaque substrates or substrates in which the backreflection is minimized or suppressed by different methods. In the present research we used a transmission and reflection photoellipsometry…
In this study the wound healing response of full-thickness skin defects was enhanced through the use of acidic fibroblast growth factor using a collagen scaffold. The objectives of this study were (1) to compare the facilitatory effects of acidic fibroblast growth factor on the cellular response (fibroblast, neutrophi…
Studies are outlined which have led to the production of large samples, of dimensions 2-10 cm, of organic electro-optic materials. The perfection of these is defined. The influence of lattice imperfections on the evaluation of fundamental physical parameters related to electro-optic device behaviour is discussed. The…
The microscopic mechanism of diffusion-type solid-solid first-order transitions was studied in boron nitride. This substance exhibits an extreme case of transitions between very different lattices, hexagonal (graphite-like) and cubic (diamond-like) phases, accompanied by a large change in the volume. A boundary betwee…
The columnar arrangement of π-stacked phthalocyanines (Pcs) is a promising structure for materials with special optical, electrical, and photo- and semiconducting properties. The requirements for obtaining optimal materials properties are discussed, and approaches towards the synthesis of mesomorphic Pcs that satisfy…
The quiescent nonisothermal bulk crystallization kinetics of two high-density polyethylene resins were investigated by a modified light-depolarizing microscopy (LDM) technique. The technique allows studies at average cooling rates up to 2500°C/min. The polymer was found to crystallize at a pseudo-isothermal temperatur…
A numerical model is developed describing the very fast process of microstructure evolution under the common action of nucleation and diffusional growth of minority phase droplets during cooling of a hypermonotectic alloy through the miscibility gap. The model is validated comparing it with an analytical solution obta…