Materials Literature
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Filled and gum compounds of Isobutylene-Isoprene rubber were extruded through a laboratory extruder at various feeding rates, different temperatures and revolutions per minute. The extruded compounds were vulcanized up to their optimum cure times and the mechanical properties of the vulcanizates were determined. The p…
An overview will be given of some recent results of microstructural electron microscopy studies on martensitic systems. The precursor structure observed in a ternary Ni-Mn-Ti alloy and its correlation with the ensuing stacking sequence is presented. New types of materials of a well known alloy, in casu splat-cooled an…
Transmission electron microscopy and scanning force microscopy of negative-stained, carbon-coated replica and mica-adsorbed preparations of 200 microM poly r(A-U) and 50 microM ethidium bromide/200 microM poly r(A-U) have been employed to evaluate ethidium-induced changes in poly r(A-U) topology. Poly r(A-U) alone exh…
Temperature dependence of the magnon frequency was studied for cubic MnTe epilayers by the Raman scattering measurements. Experimental data are compared to the results of theoretical calculations performed within the framework of the Heisenberg model using Green's function formalism.
Rayleigh-Brillouin spectra near the α-INC-β phase transition of quartz were measured. Near the INC-phase, a plateau appears between the LA-mode and the Rayleigh line. In order to take account of the interaction between the continuum (two phonon scattering from the soft branch) and the discrete LA-mode, Fano's formula…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTNitrosamine/2,3-Dichloro-5,6-dicyano- 1,4-benzoquinone (DDQ) Complexes and the Formation of Donor-Appended DDQ Chains in the Solid StateMelinda L. Greer and Silas C. BlackstockView Author Information Department of Chemistry The University of Alabama Tuscaloosa, Alabama…
The stress-induced martensitic transformation has been studied at different temperatures T>Ms. The application of a stress o on a shape memory alloy leads to the apparition of oriented variants of martensite in the direction of the stress. It causes the superelastic effect. Beyond a critical stress o,, variants grow u…
Abstract Nanostructured mesoporous silicates displaying hexagonally arranged channels, templated using a liquid crystal mesophase, were investigated using H‐2 and N‐15 NMR spectroscopy. It is shown that N‐15 MAS NMR spectroscopy allows to estimate the surface acidity of mesoporous materials by measuring the N‐H bond l…
The field of atomic and molecular photoionization has undoubtedly been transformed by the use of synchrotron radiation. In the mid-1960's the 180 MeV electron synchrotron at the National Bureau of Standards, Washington, DC, was used to discover many resonances in the photoionization continua of atoms and simple molecu…
We report on the specific heat, $C(T)$, measurements in the temperature ranges 4.5 K $<T<$ 30 K and 130 K $<T<$ 730 K of a one-dimensional carbon crystal phase synthesized by condensation of high-temperature carbon gas. Even at the lowest achieved temperatures, the measured $C(T)$ dependence, to the first…
The temperature induced transformation of single crystalline Ni -31.1% Mn -17.7% Ga (at%) shape memory alloy with Ms -446 K has been studied by means of dynamic mechanical analysis (DMA), calorimetry (DSC).dilatometq.three point bending tests and TEM.Two maxima in internal friction (IF) spectra on cooling and a single…
Based on the Pippard-Buckingham-Fairbank relation, a theory of critical ultrasonics near the isotropic-nematic transition in a liquid crystal is developed. This allows us to demonstrate that the attenuation data at different frequencies do indeed collapse on a single scaling plot in the isotropic phase.
Contamination of structures to be analyzed in an electron microscope is a severe problem for dimensional metrology applications, especially for low voltage electron microscopy. Two methods for contamination reduction which do not use a temperature variation of the sample or its environment have been investigated in th…
Abstract The monomer unit triad sequence distribution and the cis/trans linkage configurations at the cyclic maleic anhydride (MA) units in the copolymers of styrene (ST) and MA prepared in CCl 4 with AIBN at 50°C were quantitatively determined by 13 C DEPT NMR spectroscopy. So much as 61 % of the linkages at the MA u…
Experiments on the kinetics of O 2 depletion in air-saturated (65 ppm O 2 ) Jet-A (POSF-2827) fuel containing 4 ppm Fe 2 O 3 were conducted with a near-isothermal flowing test rig (NIFTR) using passivated heat-exchanger tubing over the range 418−468 K. The kinetic data are consistent with an oxidation mechanism involv…
Germanium and silver atomic surroundings of ${\mathrm{Ag}}_{2}{\mathrm{GeS}}_{3}$ glass have been studied by anomalous wide-angle x-ray scattering. The structural parameters deriving from the simulations of the differential distribution functions, characterizing selectively Ge and Ag environments, show that the medium…
Hydrogen adsorption on a Cu/MgO catalyst is investigated using in situ 1 H NMR. The adsorption is largely homogeneous, demonstrating reasonable agreement with the Langmuir isotherm and only small variations in the frequency shift and spin−lattice relaxation time with increasing coverage. The catalyst is investigated u…
Abstract Cyclic voltammetry was used to characterize the oxidation‐reduction behavior of a series of novel hexacoordinate silicon(IV) porphyrin complexes. Each (Por)SiX 2 [Por = the dianions of the porphyrins: tetrakis( p ‐tolyl)porphyrin (TTP), tetraphenylporphyrin (TPP), tetrakis( p ‐trifluoromethylphenyl)porphyrin…
The mean value of a measurement set with precision σ has an offset relative to an accepted standard. Calibration of an instrument involves subtracting the offset between the mean value and the reference. Unfortunately, imaging characteristics for most types of microscopes are not constant. Slight changes in feature wa…
Small angle time-resolved X-ray diffraction was used to monitor the behaviour of the smectic layers during the electric field induced planar to homeotropic transition in a smectic A cell possessing a chevron layer geometry. The liquid crystal material used was S3, from Merck Ltd, and was sandwiched in a 15 mum paralle…