Materials Literature
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Optically isotropic films of an amorphous copolymer containing azobenzene moieties (pDR1M- co -MMA) were irradiated by interfering two circularly contrarotating polarized laser beams and permanent holographic diffraction gratings were prepared. These involve the formation of both birefringence and surface relief grati…
Abstract Soils, subsoils, and aquifer materials can be modified with hydrophobic cationic surfactants to increase their sorptive capabilities for organic contaminants. In this study, we evaluated the adsorption/desorption of hexadecyltrimethylammonium (HDTMA) by smectitic soils, and the sorptive characteristics of the…
We report here a detailed experimental study, establishing the surface-initiated mechanism for the photoinduced relief grating formation on azobenzene functionalized polymer films. The grating formation process is found to be strongly dependent on the nature of the surface (20−200 Å), while the birefringent grating ap…
The packing in self-assembled nanocrystal superlattices is determined to a large extent by the geometry of the nanocrystals, as is demonstrated here by the preparation and analysis of wellordered arrays of predominantly tetrahedral silver nanocrystals. The Figure shows the model proposed to explain the monolayer self-…
The zero shear melt viscosity, eta0, for a variety of dendritic poly(benzyl ether) macromolecules has been measured. The viscosity of low generation dendrimers exhibits a strong molecular mass, M, dependence, yet, direct proportionality between eta0 and M is observed at higher generations. The viscosity scales with M…
The magnetization of a ${\mathrm{Mn}}_{12}$-acetate single crystal was measured with a cantilever magnetometer to temperatures below 60 mK. Contrary to expectations we did not observe steps in the hysteretic magnetization with indices higher than 11. The data suggest a significant degree of higher-order anisotropy. Th…
Abstract The most common cause of composition modification to a specimen during electron probe microanalysis is the field induced migration of light elements. This is an indirect effect which occurs in response to the long range electric fields that form when dielectric specimens suffer charge imbalance. The result is…
Abstract A novel terephthalic acid derivative based on benzocyclobutene, XTA, has been used as a comonomer in the preparation of thermally crosslinkable poly(ethylene terephthalate) copolymers. We have examined the rheological properties of a series of such polymers containing varying monomer percentages of the XTA co…
The thermal expansion characteristics of the reinforcement and matrix constituents in ceramic composites have a strong influence on a number of aspects of the composite performance. Thus the toughn ...
The cofactor specificity of serine hydroxymethyltransferase (SHMT) activities was tested in extracts of several methanogens using tetrahydromethanopterin (H 4 MPt) from Methanobacterium thermoautotrophicum Marburg, tetrahydrosarcinapterin (H 4 SPt) from Methanosarcina barkeri, and tetrahydrofolate (H 4 folate) as the…
Molecular sieves of the type CoAPO-5 have been studied by TEM and ac susceptibility measurements. In the as-synthesised state the material is paramagnetic due to the isolated cobalt ions and microstructurally it looks very homogeneous. After calcination the system develops very small cobalt-containing particles of A s…
Conventional magnetic parameters and Barkhausen noise have been measured in pressure vessel steel samples both as-received and irradiated with doses of up to 10/sup 18/ n/cm/sup 2/. The conventional magnetic parameters, i.e. coercive force, remanence and maximum induction did not change significantly with irradiation,…
Abstract Most solids which are handled in large quantities are stored in the form of small particles, for ease of handling. The storage containers for these solids are generically termed silos, though several other words are in use for special applications. Silos are used in most countries in the world to store a huge…
Hysteretic energy losses which occur for arbitrary, not only cyclic, variations of the magnetic field are the subject of this paper. These losses are derived for the media which can be described by the vector Preisach model of hysteresis. An algorithm for computation of the losses is obtained based on the state diagra…
The oxygen nonstoichiometry, the total conductivity, and the electronic conductivity of were measured by using high temperature gravimetry, dc four‐terminal method, and Hebb‐Wagner's dc polarization technique, respectively. The change in the oxygen nonstoichiometry was explained by assuming Ce' Zr , Ca'' Zr , and as m…
Single crystals of GeS 2 are grown by two methods: crystallization from a melt and chemical vapor transport. All crystals are found to have a monoclinic structure with the unit-cell parameters a =11.45 Å, b =16.09 Å, c =6.7 Å, and β =91°. The reflection and transmission spectra are measured in the region of the absorp…
The X-ray crystal structures of thioindigo derivatives, 4,4‘7,7‘-tetrachlorothioindigo and 4,4‘,5,5‘,7,7‘-hexachlorothioindigo, have been determined to clarify the photocarrier generation process in these compounds. The crystals belong to the same space group ( P 2 1 / a ), but the stacking manner of the molecules dif…
Pure nickel coupons were used as substrates in the deposition of alumina (Al 2 O 3 ) from the reaction of aluminum chloride (AlCl 3 ) with hydrogen/carbon dioxide gas mixtures in the temperature range of 954°–1100°C and system pressures of 2.7–13.3 kPa. The apparent activation energy estimated from the coating growth…
Influence of surface roughness on magnetic properties of Fe/sub 78/Si/sub 9/B/sub 13/ and Fe/sub 78/Si/sub 14/B/sub 8/ amorphous alloy ribbons was investigated. Magnetic induction in an external field of 800 A/m, B/sub 8/ of Fe/sub 78/Si/sub 9/B/sub 13/ ribbon increased slightly with decreasing surface roughness, whil…
The effects of vanadium content, ranging from 0.002 to 0.011 wt-%, and annealing temperature on recrystallisation and grain growth characteristics, texture development, and magnetic properties in cold rolled 0.3% Si electrical steel have been studied.The results indicate that fine VN and VC, precipitated during hot ba…