Materials Literature
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Abstract Polyethylene and polystyrene composites filled with high‐volume content of filler particles (quartz or Al 2 O 3 ) were prepared by ordinary melt‐casting method to effectively increase the thermal conductivity. The result, however, suggested that fractional void volume cssentially occupied by filler particles…
Formation of radiation damage and its recovery in ${\mathrm{UO}}_{2}$ single crystals were investigated in the temperature range from 5 to 293 K. The samples were implanted with Xe ions at 5 K and subsequently in situ analyzed using the ion-channeling technique. Successive measurements were performed during the warmin…
Quasi-phase-matched second-harmonic generation has been observed in a periodically poled nonlinear optical polymer waveguide. Key elements in this demonstration include novel nonlinear optical polymers that can be spin coated, the design and fabrication of periodic electrodes for periodic poling and the optimization o…
A high-speed nematic liquid crystal modulator with response time less than 100 μs at room temperature was demonstrated. The effects that contribute to the observed high speed are the transient nematic effect, a new liquid crystal mixture, and a holding voltage technique.
Indirect evidence is presented that free-standing Si quantum wires can be fabricated without the use of epitaxial deposition or lithography. The novel approach uses electrochemical and chemical dissolution steps to define networks of isolated wires out of bulk wafers. Mesoporous Si layers of high porosity exhibit visi…
Analysis of anions ability to transfer from one structural position into another is applied for predicting the properties of apatite.
Abstract Stoichiometric Al-bearing ferrites[AlxFe3-xO4 (x=0.05–0.46)] are formed by a transformation reaction from γ-FeOOH in an aqueous suspension. The transformation reaction proceeds in a suspension containing γ-FeOOH, Fe(II) and Al ions without oxidation at 25°C and a pH of 9.5–11.0.
Abstract A novel substituted acetylene monomer, 4,4′‐(1,2‐ethynediyl) bis (phthalic anhydride) (EBPA) was made in six steps from 4‐nitro‐ N ‐methylphthalimide (4‐NPI) including two palladium‐catalyzed acetylene coupling steps. Several new polyimides were prepared from this monomer and six aromatic diamines. In additio…
Detailed information on the preparation and application of antiozonants to the production of rubber has been collected from the patents published till 1987 inclusive. From among the numerous organic compounds acting as antiozonants and antioxidants, several classes can be distinguished and grouped on the gasis of the…
Abstract X-Ray powder diffraction data and unit cell parameters of industrially produced, as well as bench scale prepared, ammonium paratungstate tetrahydrate are reported and compared with current Powder Data File (PDF) (1989) patterns. A least-squares refinement resulted in two slightly different unit cells. Both ce…
On the basis of broad experimental material, the authors made the following conclusions: inert fillers influence the combustion of polymeric materials strongly only at high weight content; the fillers, that decompose into volatile products as CO2 and H2O can more strongly influence the combustion of composite compound…
The dielectric properties of the nematic liquid crystal, 4-4′-n-pentylcyanobiphenyl (K15), and three binary mixtures of K15 with 4-[4′-alkylcyclohexyl]cyanophenyl homologs have been studied. The parallel, perpendicular and isotropic dielectric constants are given as a function of temperature. All measurements were mad…
Crystals of the calcium-containing lysozyme from horse milk have been grown by precipitation with sodium phosphate. The crystals are orthorhombic space group P2(1)2(1)2(1) with cell dimensions a = 53.2, b = 57.1, and c = 38.2 A and contain a single molecule in the asymmetric unit. The crystals are suitable for high re…
Different models for calculation of the temperature rise under an electron beam spot are reviewed. From a study of the cathodoluminescence (CL) shift as a function of temperature in CdS, a model for determining the temperature rise is proposed.
The effects of high external pressures on the micro-Raman spectra of potassium chromate, K 2 CrO 4 , and potassium tungstate, K 2 WO 4 , have been investigated for pressures approaching 45 kbar. There is no evidence for a pressure-induced phase transition in the chromate, but there is clearly such a transition at ∼13…
Abstract Polyetheretherketone‐polydimethylsiloxane (PEEK–PDMS) block copolymers were synthesized from the condensation of dimethylamino terminated PDMS and hydroxy terminated PEEK oligomers in 1‐chloronapthalene. Yields for block copolymers synthesised from low molecular weight PDMS oligomers were good but yields were…
The characteristics of excimer lasers and the nature of ablation and etching processes are described. The two kinds of laser ablation mechanisms, thermal and electronic, are discussed. Thermal processes all rely on an intense laser pulse to heat a surface very rapidly. Electronic mechanisms do not rely on heating. Two…
Some optical investigations including measurements of birefringence and angle between the extinction positions in different domains, have been performed on [N(CH3)4]2MnCl4, In addition the domain structure has been studied using an optical microscope. The observed anomalies in the birefringence measurements clearly co…
Abstract The effects of rubber content, particle size and interparticle spacing on the fracture behaviour of toughened polymers over a range of strain rates and temperatures are discussed with particular reference to high‐impact polystyrene and rubber‐toughened nylons. It is concluded that the limiting factor in deter…
The effect of local anesthesia containing epinephrine on the survival of split- and full-thickness skin grafts remains unclear. In this blinded study, Xylocaine with or without epinephrine was injected subdermally prior to harvesting of split-thickness and full-thickness skin grafts on the dorsum of rabbits. After pro…