Materials Literature
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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…
We describe a method to estimate the thermal conductivity of the substrate, the dielectric layer, the phase-change (PC) layer, and the reflective layer of PC optical recording media. The method relies on the amorphous-to-crystalline phase transition that occurs in the PC layer and takes advantage of the difference in…
Enzymatic synthesis, employing horseradish peroxidase (HRP), has been used to prepare a novel photoactive azopolymer, poly(4-phenylazophenol), from 4-phenylazophenol. FTIR, FT-Raman, and NMR ( 1 H, 13 C) spectroscopy show that the coupling reaction occurs primarily at the ortho positions with some coupling at the meta…
[equation--see text] Introducing 3-methoxy or 3,5-dimethoxy substituents on the 4-hydroxyphenacyl (pHP) photoremovable protecting group has been explored with two excitatory gamma-amino acids, L-glutamic acid and gamma-amino butyric acid (GABA). These substituents significantly extend the absorption range of the pHP c…
The character of adsorbed layers containing both polyelectrolyte and surfactant depends on the type of polyelectrolyte used and the surfactant concentrations, as demonstrated by several recent studies. However, the layer properties also depend on the experimental pathway. This shows that the adsorbed layers can be tra…
Results are reported of thermocapillary flow experiments performed aboard the Spacelab. Oscillatory thermocapillary flows were investigated in open cylindrical containers filled with 2 cS kinematic viscosity (Prandtl number = 27 at 25 °C) silicone oil. The fluid was heated by a cylindrical cartridge heater placed at t…
We conducted three sets of depth-of-penetration experiments with limestone targets and 3.0 caliber-radius-head (CRH), ogive-nose steel rod projectiles. The ogive-nose rod projectiles with length-to-diameter ratios of ten were machined from 4340Rc45 and Aer Met 100Rc53 steel, round stock and had diameters and masses of…
This article addresses a fundamental problem faced by the ab initio community: the lack of an effective formalism for the rapid exploration and exchange of new methods. To rectify this, we introduce a novel, basis-set independent, matrix-based formulation of generalized density functional theories which reduces the de…
Magnetization, heat capacity, electrical resistivity, thermoelectric power, and Hall effect have been investigated on single-crystalline Ce_2PdSi_3. This compound is shown to order antiferromagnetically below N'eel temperature (T_N) \~3 K. The Sommerfeld coefficient far below T_N is found to be about 110 mJ/K^2 mol Ce…
This paper is an introduction to some of the main present issues in the theory of structural glasses. After recalling a few experimental facts, it gives a short account of the analogy between fragile glasses and the mean field discontinuous spin glasses. The many valley picture is presented, and a brief account of rec…
The ZnO film with 6 mm symmetry is one kind of functional films with different use. The columnar microstructure in the film has an affect on the properties of materials. In this paper, ZnO/Si film was deposited by planar magnetron sputtering. The columnar microstructure was examined with SEM and TEM. The SEM cross ima…
A new synthesis technique, namely double mechanical alloying (DMA), has been developed to prepare Al-Fe-V-Si nanocrystalline powders, and during the DMA, XRD result indicate that a transformation from α-Al 13 (Fe,V) 3 Si + fcc-Al phase to quasicrystalline + fcc-Al phase was observed.