Materials Literature
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Effect of the aggregation state of montmorillonite clays of types SAz-1 and SWy-1 on the adsorption of the monovalent organic cation chlordimeform was studied. The shapes of the adsorption isotherms were related to the degree of dispersion of the clay, changing from S- to L-type by decreasing clay concentration. Unlik…
Handbook of thermal analysis , Handbook of thermal analysis , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
Sequential addition of a polyanion, poly(styrene sulfonate), and a polycation, polyaniline, lead to the formation of layer-by-layer films at different solid surfaces. The prime variables which determine the films formation of poly(styrene sulfonate) (PSS)/polyaniline (PANI) were the polymer charge and ionic strength.…
The selection rules for dipole and Raman activity can be relaxed due to local distortion of a crystalline structure. In this situation a dipole-inactive mode can become simultaneously active in Raman scattering and in dipole interaction with the electromagnetic field. The later interaction results in disorder-induced…
This communication describes preliminary results of an experimental investigation of the binding of Cu(II) ions to poly(amidoamine) (PAMAM) dendrimers in aqueous solutions. Dendrimers are highly branched polymers with controlled composition and architecture consisting of three structural components: a core, interior b…
We report on the effects of using SrFe7Al5O19 as a buffer layer for growth of high-quality epitaxial barium-ferrite thin films on sapphire substrates. X-ray diffraction studies reveal that the buffer layer causes the interfacial strains in the barium-ferrite films to relax. As a result, the ferromagnetic resonance lin…
The Stokes flow occurring within a non-neutrally buoyant spherical droplet translating by buoyancy through an immiscible liquid which is undergoing simple shear is shown to be chaotic under many circumstances for which the droplet translates by buoyancy through the entraining fluid. This flow is easily produced, for e…
A Cu (400 Å)/Al (50 Å)/polyimide system showed larger adhesion strength than that of Cu (400 Å)/polyimide after N2+ ion beam mixing. X-ray emission spectroscopy was performed to elucidate the mechanism of adhesion enhancement of the ion beam mixed Cu (400 Å)/polyimide with a thin Al buffer layer. Cu L2,3 x-ray emissio…
The electrical activity of numerous electroceramics originates with space charge potential across internal interfaces. Space charge formation and the resultant potential barrier at interfaces are believed to be responsible for many interesting and useful properties of electroceramics, ranging from nonlinear current–vo…
We have used coherent soft-x-ray dynamic light scattering at the Bragg peak to measure the thermally driven layer fluctuations in freely suspended films of five different smectic- $A$ liquid crystals: 4O.8, 7O.7, 8CB, 8OCB, and 10OCB. The measured relaxation times at a scattering wave vector corresponding to the inter…
Azobenzene polymers and oligomers show intriguing surface relief features when irradiated with polarized laser light. We show through atomic force microscopic investigation of side-chain azobenzene polymers after irradiation through an amplitude mask that large peaks or trenches result depending on the architecture of…
The transition from normal to fast regimes of the longitudinal sound velocity has been studied by inelastic x-ray scattering in liquid water as a function of momentum transfer ( $1--12{\mathrm{nm}}^{\ensuremath{-}1}$) and temperature (260--570 K), using pressure (0--2 kbar) to keep the density at $\ensuremath{\rho}\en…
Recent high pressure x-ray experiments show that, contrary to traditional expectations, the NaCl structure is not present in covalent semiconductors, and the diatomic $\ensuremath{\beta}\ensuremath{-}\mathrm{Sn}$ structure is absent in all compound semiconductors. We explain these systematic absences in terms of dynam…
An optically addressed ultraviolet light modulator has been demonstrated which exploits the optical anisotropy in a ZnO film epitaxially grown on (011̄2) sapphire. This device achieves both high contrast and high speed by exploiting the anisotropic bleaching of the anisotropic absorption and concomitant ultrafast pola…
Nearly a 50% decrease of resistivity ρ(T,x) due to just 4% Cu doping on the Mn site of La(2/3)Ca(1/3)Mn(1-x)Cu(x)O(3) is observed. Attributing the observed phenomenon to the substitution induced decrease of the spin polaron energy E_s(x) below the Curie point T_C(x)=T_C(0)(1-x), all data are found to be well fitted by…
We propose a first principles computation of the equilibrium thermodynamics of simple fragile glasses starting from the two body interatomic potential. A replica formulation translates this problem into that of a gas of interacting molecules, each molecule being built of $m$ atoms, and having a gyration radius (relate…
The thermal conductivity of polycrystalline semiconductors with type-I clathrate hydrate crystal structure is reported. Ge clathrates (doped with Sr and/or Eu) exhibit lattice thermal conductivities typical of amorphous materials. Remarkably, this behavior occurs in spite of the well-defined crystalline structure and…
Short jute fiber-reinforced polypropylene (PP) composites were prepared using a high-speed thermokinetic mixer. A compatibilizer was used to improve the molecular interaction between jute and PP. Both the percent weight fraction of the jute fiber and compatibilizer were varied to study the dynamic mechanical thermal (…
The mechanical properties of tossa jute fibers were improved by using NaOH treatment process to improve the mechanical properties of composites materials. Shrinkage of fibers during this process has significant effects to the fiber structure, as well as to the mechanical fiber properties, such as tensile strength and…
Polymerization of 4,4′-bismaleimidediphenyl methane and N-phenylmaleimide was conducted in dimethyl formamide, catalyzed by nanocrystalline titania. The monomers and polymers involved were characterized with infrared spectroscopy, 1H-NMR, and 13C-NMR, respectively. The mechanism of the catalyzed polymerization was dis…