Materials Literature
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More than 130 years ago it was first recognized that the observed response from many diverse substances may exhibit two distinct types of nonexponential relaxation. Although the Kohlrausch-Williams-Watts (KWW) stretched exponential and Curie-von Schweidler (CvS) power law have since been used to characterize the obser…
Reactive ion etching of PbZrxTi1−xO3 (PZT) thin films was studied by using Cl2/C2F6/Ar gas chemistry in an inductively coupled plasma (ICP). PZT films were deposited on Pt/Ti/SiO2/Si substrates by the sol–gel process. PZT films were etched by varying the etching parameters including coil rf power, dc-bias voltage to t…
High-resolution surface tension measurements have been carried out on the free-standing films of more than 30 selected liquid-crystal compounds in their smectic phases. Surface tension (γ) values falling into major categories of 27, 24, 21, 13, and 11.5 dyn/cm have been obtained. The dependence of γ on specific termin…
Biologically compatible implant materials are commonly used in medical applications. The physico-chemical nature of the implant surface influences macromolecular binding. In the case of titanium implants, these interactions are influenced by a thin titanium oxide layer (5–70 Å), the main oxide species is titanium diox…
A new layered nanocomposite, which is one-to-one interstratified with a montmorillonite layer and a mixed SiO 2 /TiO 2 sol particle one, has been prepared by ion exchange reaction of the Na + ion in montmorillonite with the positively charged SiO 2 /TiO 2 sol particles. The ion exchange reaction was performed at three…
The performance and safety of rechargeable batteries depend strongly on the materials used. Lithium insertion materials suitable for negative and positive insertion electrodes are reviewed. Future trends, such as alternative materials for achieving higher specific charges—the Figure shows a scheme for reversible lithi…
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…