Materials Literature
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In systems like glass-forming melts in the vicinity of the vitrification temperature or polymers, the elastic strains which evolve as a result of formation and growth of an ensemble of clusters may result in a partial or total inhibition of cluster growth and Ostwald ripening already in the absence of elastic interact…
Syndiotactic polystyrene (sPS) films were obtained either by casting or by melt crystallization in the β form. Different thermal treatments of the melt led to mixed α and β forms. The structural organization was investigated by x-rays, transport properties, and Fourier transform infrared analysis. The β form is charac…
A computationally simple, but accurate, model for porphyrin ring-current shifts is presented and calibrated by using X-ray and n.m.r. data from cytochrome c, cytochrome C551, cytochrome b 5, and pyridine and picoline complexes of zinc porphyrin . The model involves a multipole expansion in terms of Legendre polynomial…
Abstract X‐ray photoelectron spectroscopy and cyclic voltammetry have been used to characterize 4.9 wt.% platinum‐on‐graphite catalysts used for the oxidation with molecular oxygen of methyl α‐ D ‐glucoside in aqueous solution. Cyclic voltammetry indicates that a surface oxidic layer is formed on the platinum particle…
Abstract The structure of a disordered II b Mg-chamosite was studied using Rietveld refinement techniques and powder X-ray diffraction (CuK α , 18–120° 2 θ in 0.02° 2 θ increments). The refinement in space group CĪ yielded high precision lattice parameters (a = 5.36982(5)Å, b = 9.3031(9)Å, c = 14.2610(6)Å, α = 90.315(…
Abstract A new method for coating the inner surface of ultrahigh‐vacuum (UHV) vessels with an inert material is proposed, namely coating with highly oriented graphite layers which precipitate on the surface of a carbon‐doped nickel substrate. By using various surface analytical methods, characterization of the precipi…
NOx exhaust emissions for gas turbine engines with lean-premixed combustors are examined as a function of combustor pressure (P), mean residence time (τ), fuel-air equivalence ratio (φ), and inlet mixture temperature (Ti). The fuel is methane. The study is accomplished through chemical reactor modeling of the combusto…
The charge behavior in an organic photoconductor (OPC), which can be used as an electrophotographic receptor, was observed using the pressure wave propagation method. When a pulse pressure wave passes through the sample, a displacement current is generated. The charge distribution is obtained from the measurement of t…
With application in infrared lenses , lanthanum sulphide and calcium lanthanum sulphide are ceramic materials which require a low defect density in order to minimize light scattering and maximize mechanical strength. Solution routes to monodispersed ceramics are investigated, offering materials with improved packing i…
Partial discharge (PD) detection for live UHV/EHV power cables and accessories is the most important test on cable systems, to prevent problems caused by minor mistakes in jointing the cable. A new PD detecting method is proposed. A REDI (resonance type partial discharge) sensor was developed for detecting PD occurrin…
Plate impact experiments are conducted to study the dynamic fracture processes which occur on submicrosecond time scales. These experiments involve the plane strain loading of a plane crack by a square tensile pulse with a duration of approximately one microsecond. The crack-tip loading rates achieved are K1 ˜ 108MPam…
Poly(ethylene oxide) (PEO)‐based Zn(II) halide electrolytes with optimized compositions exhibit rather high conductivities compared to other PEO solutions of divalent cation salts. Chemical diffusion studies have clearly demonstrated that both Zn(II) and Br(‐ I) are mobile. It appears that Zn(II) cations occur in two…
Abstract According to Lippmann (1977, 1982) wide compositional variations and excess enthalpies of mixing calculated with electrostatic models imply that clay minerals of variable composition are dis-equilibrium solids. However, recent ATEM analyses of illite samples indicate compositional homogeneity of single illite…
Abstract Polymide films made from diarylanhydrides with oxygen, carbonyl, and hexafluoroisopropylidene 6F bridging groups are photolabile when irradiated with unfiltered light from a medium‐pressure mercury lamp. The presence of oxygen is necessary to the photolytic degradation process, which results in the ultimate o…
RATIONALE AND OBJECTIVES: The authors investigated whether iron oxide particles can be used as a magnetic resonance imaging (MRI) contrast agent to image abscesses in a two-stage experimental design. METHODS: Human buffy coat was incubated with iron oxide particles of different sizes and coatings. Smears of the incuba…
The influence of redox site loading, supporting electrolyte concentration, pH, and temperature on the rate of homogeneous charge transport, characterized by , and the rate of heterogeneous electron transfer, characterized by the standard rate constant , has been examined for films on glassy carbon electrodes in sulfat…
Abstract Hydroxyaluminosilicate (HAS) ions prepared from hydroxy-Al (HyA) ions and orthosilicic acid at different NaOH/Al molar and Si/Al atomic ratios were fixed in the interlayer spaces of vermiculite (Vt). The electric charge and surface characteristics of HAS-Vt and HyA-Vt complexes formed were investigated in the…
SUMMARY A new three‐parameter function is proposed that improves the ‘classical’ power‐law function for background subtraction processing at low energy losses in electron energy‐loss spectroscopy. The variation of the edge integrals with the width of the pre‐edge window Γ is reduced by a factor of at least five (of in…
NiK-edge EXAFS and XANES and optical spectroscopy indicate strong differences in the Ni environments in glasses of feldspar stoichiometry, in relation to the polarizing power of the associated alkali. Mostly 4 Ni and coexisting 4 Ni and 5 Ni are found in K 2 NiSi 3 O 8 and NaNiSi 3 O 8 glasses respectively
The authors have developed a new method for the detection of AC dissipation in dielectric materials under high AC field. Using this technique, high-field dielectric loss properties and their relation to AC dissipation current of low-density polyethylene (LDPE) films are measured. Near room temperature, tan delta of a…