Materials Literature
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We study the effect of planar defects in phononic crystals of spherical scatterers. It is shown that a plane of impurity spheres introduces modes of vibration of the elastic field localized on this plane at frequencies within a frequency gap of a pure phononic crystal; these show up as sharp resonances in the transmit…
An ab initio study of the doping of alkali halide crystals (AX: A = Li, Na, K, Rb; X = F, Cl, Br, I) by ns2 anions (Ag- and Cu-) is presented. Large active clusters with 179 ions embedded in the surrounding crystalline lattice are considered in order to describe properly the lattice relaxation induced by the introduct…
The room temperature structure of aluminum, copper and gold infinite nanowires is studied. The molecular dynamics simulation method and the same type of the embedded atom potentials made by Voter and coworkers are used. It was found that multi-shelled and various filled metallic nanowires exist depending on the metal…
Four different redox states of the trinuclear ruthenium clusters of general formula [Ru3(μ3-O)(μ-CH3CO2)6(L)3] (L = xylyl isocyanide (1), tert-butyl isocyanide (2)) were generated electrochemically in solution and studied by reflectance infrared spectroelectrochemistry. The IR spectra in the ν(C⋮N) region show multipl…
Two new lupane derivatives, 3beta,6alpha-dihydroxylup-20(29)-ene (1) and 6alpha-hydroxylup-20(29)-en-3beta-octadecanoate (2), have been isolated from the stems of Periploca aphylla, in addition to beta-sitosterol and lupeol. The structures of 1 and 2 were determined by spectral and chemical methods. Compound 1 showed…
This chapter explores crystals in formulated products. Having developed a process for preparing a product in a crystalline form, it is important to appreciate that these crystals usually then have to be transformed into a product. In some cases, this is achieved by further chemical reaction, in others by formulation.…
Ultracentrifuge and light scattering measurements are performed to study static and dynamic properties for a suspension of well-defined platelike colloids to first order in concentration. Both the form factor and the diffusion coefficient at infinite dilution match theoretical expressions if polydispersity is incorpor…
A series of homoleptic bis[2,3,9,10,16,17,23,24-octakis(octyloxy)phthalocyaninato] rare earth(III) sandwich complexes {M[Pc(OC8H17)8]2 (M = La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Y, Ho, Er, Tm) (1) and (3)–(13), and HCe[Pc(OC8H17)8]2 (2)} has been prepared by the cyclic tetramerization of 4,5-di(octyloxy)phthalonitrile on th…
Waste minimisation has a number of aims which include enhancing the intrinsic selectivity of any given process, providing a means of recovering reagents in a form which allows easy regeneration and the replacement of stoichiometric processes with catalytic ones. Solids, as catalysts or as supports for other reagents,…
Colloidal silica has been polymerized in the aqueous domain of lyotropic liquid crystal phases in ternary surfactant (Pluronic F127 or P123)−cosurfactant (butanol, pentanol, or hexanol)−water systems to create optically transparent mesostructured surfactant−cosurfactant−silica monoliths. The use of ternary systems enr…
Poly(amidoamine), or PAMAM, dendrimers in the G5−G10 range were imaged by tapping mode atomic force microscopy (AFM). Individual dendrimer molecules could be clearly observed in the AFM images, which showed that these dendritic particles appear to be monodispersed, dome-shaped, and randomly distributed on the mica sur…
The exfoliation of acid-exchanged K 4 Nb 6 O 17 with tetra( n -butyl)ammonium hydroxide in water produces a colloidal suspension of individual sheets, which roll into loosely bound tubular structures. The tubule shape can be made permanent via precipitation of the colloid with alkali cations. Atomic force microscopy a…
In this letter we report that the current induced destabilization of the charge ordered (CO) state in a rare-earth manganite gives rise to regions with ferromagnetic correlation. We did this experiment by measurement of the I-V curves in single crystal of the CO system Pr$_{0.63}$Ca$_{0.37}$MnO$_{3}$ and simultanously…
The formation of coherently strained three-dimensional islands on top of the wetting layer in Stranski-Krastanov mode of growth is considered in a model in 1+1 dimensions accounting for the anharmonicity and non-convexity of the real interatomic forces. It is shown that coherent 3D islands can be expected to form in c…
Nano-diameter tubules made of folded graphitic sheets have drawn the attention of physicists ever since the advent of fullerene research. These are interesting because of their conductivity (depends upon chirality) as well as their mechanical properties. Bunches of such tubes, single-walled and each of same diameter (…
<italic>From Molecules to Crystallizers</italic> begins by stating that crystallization is one of the oldest separation processes used in the chemical industry and is still one of the most important. It is also going through an exciting renaissance, the text argues, with the result that it is becoming yet more central…
A calculation of the optical conductivity and related optical properties of liquid silicon is presented. Starting from the results of a single superchain/effective medium approximation for the electronic properties, the frequency dependent conductivity is evaluated in terms of the Kubo-Greenwood formula. For a fast co…
We present the results of crystallization and amorphization studies on a thin-film sample of Ge(2)Sb(2.3)Te(5), encapsulated in a quadrilayer stack as in the media of phase-change optical disk data storage. The study was conducted on a two-laser static tester in which one laser, operating in pulsed mode, writes either…
A general method for the functionalization of Si-Cl terminated carbosilane dendritic molecules via organolithium or organomagnesium reagents is described. Quantitative exchange of the bromine atoms of 4-bromophenyl-functionalized dendrimers affords polylithiated species that are valuable starting materials for further…
Dendronization with the first generation (G1) building block 10b of the polystyrenes 13c and 14c carrying first (G1) and second generation (G2), amino-terminated appendant dendrons is reported. Comparison of the 1 H and 13 C NMR spectra of the resulting G2 and G3 polystyrenes ( 15, 17a ) with those recorded of the sam…