Materials Literature
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Lightly etched single-walled carbon nanotubes are chemically reacted to form rings. The rings appear to be fully closed as opposed to open coils, as ring-opening reactions did not change the structure of the observed rings. The average diameter of the rings was 540 nanometers with a narrow size distribution. The nanot…
4-dimethylaminopyridine (DMAP) is the answer to the quest for an efficient transfer of metallic nanoparticles from organic to aqueous solutions. The picture shows the transfer of gold nanoparticles from toluene to water by the addition of DMAP (0.1 M, pH 10.5). This method enables the generation of high concentrations…
ADVERTISEMENT RETURN TO ISSUEPREVArticleDendritic Catalysts and Dendrimers in CatalysisDidier Astruc and Françoise ChardacView Author Information Laboratoire de Chimie Organique et Organométallique, UMR CNRS N°5802, Université Bordeaux I, 33405 Talence Cedex, France Cite this: Chem. Rev. 2001, 101, 9, 2991–3024Publica…
The Metropolis Monte Carlo (MMC) technique performance is compared to the performance of an iterative deconvolution method. In the MMC approach to deconvolution two Monte Carlo Procedure (MCP) are run at the same time. In one the blurred data is used as a distribution function for selection of pixels. And the second M…
Scalable rotary actuators are being developed with the help of Shape Memory Alloy (SMA) wires. Subjected to elevated temperatures SMA wires deliver large strains and high stresses. Yet their bandwidth is limited because of the time required for cooling. Bandwidth can be enhanced by miniaturizing the actuating system,…
We report our studies on the electronic structure and linear and nonlinear optical (NLO) properties of KNbO 3 using a first-principles method in the local density approximation (LDA). The calculated results for the refractive indices and second-harmonic-generation (SHG) coefficients agree well with experimental result…
Using a generalized tight-binding model, we study the changes induced in the electronic and mechanical properties of carbon nanotubes with encapsulated C 60 s. Provided enough overlap exists between the electronic states of the nanotube and those of the C 60 s, a tiny gap (~0.01-0.02 eV) opens in the band structure of…
The magnetic properties and 57 Fe Mössbauer spectra of the compounds YFe 11 TiH x ( x = 0, 1) were investigated. The magnetocrystalline anisotropy of YFe 11 Ti and its hydride was studied by analysing the hard and easy magnetization curves of single crystal samples in the temperature range 4.2–300 K. The spontaneous m…
A general concept for photoinduced structural phase transitions is developed, in terms of the hidden multi-stability of the ground state and the proliferations of optically excited states. Taking the ionic (I) to neutral (N) phase transition in the organic charge transfer (CT) crystal, tetrathiafuluvalene-p-chloranil,…
The energies of 135 Kramers doublets extending up to the 2 H1 11/2 multiplet for Nd 3+ in a monoclinic C 2/ c space group (No 15) NdAl 3 (BO 3 ) 4 (NAB) single crystal laser have been determined from polarized optical absorption and photoluminescence measurements at 7 K. The strongly polarized character of the Nd spec…
The native point defect states in ZnO have been calculated by using a full-potential linear muffin-tin orbital method. The results show that Zn vacancy and O interstitial produce the shallow acceptor levels above the valence band. The O vacancy produces a deep donor level, while Zn interstitial produces a shallow dono…
Fe4+ content and ordering of anion vacancies in partially reduced AFexTi1-xO3-y (A = Ca, Sr; x⩽0.6) perovskites. An 57Fe Mössbauer spectroscopy study, J C Waerenborgh, F M Figueiredo, J R Frade, M T Colomer, J R Jurado
Supported metal particles may exhibit properties fundamentally different from the corresponding bulk materials. To gain insight into principles underlying size- and structure-dependent phenomena, a structural characterization of small aggregates at the atomic level is crucial, while far from straightforward. A long-st…
Abstract The prediction of chemical structures that possess higher glass‐transition temperatures ( T g 's) is crucial for designing polyimides. Because of a lack of suitable parameters, several estimation methods cannot be used for this purpose. In this study, therefore, we used molecular dynamic simulation with the D…
Abstract Adsorption of 1,3‐thiazolidine‐2‐thione (ttz), 2,5‐dimercapto‐1,3,4‐thiadiazole (dmtd) and 2‐thiouracil on a silver surface was studied by the FT‐SERS technique. The FT‐SERS spectra of all these molecules indicate dissociative adsorption on the silver surface to the corresponding thiolate ion. For ttz and 2‐t…
The “bottom-up” approach to development of direct-drop processes is a powerful, yet simple, strategy that every process chemist should consider for the development of efficient, cost-effective, and environmentally friendly processes. This approach is aided by a “parallel crystallization” technique, which allows for ra…
This paper presents research aimed at actively altering the twist distribution of a tiltrotor blade between hover and forward flight. Three different concepts-extension-twist coupled composites, bimoment actuation and discrete SMA torque tube actuation - are considered, and the torque tube appears the most feasible. P…
NMR spectroscopy experiments on thermally aged cross-linked hydroxyl-terminated polybutadiene (HTPB)/isophorone diisocyanate (IPDI) based polyurethane rubber indicated only a slight temperature dependence for the degradation products distribution but revealed the presence of chemical and dynamic heterogeneities. The s…
Rheological and near-infrared (NIR) spectroscopic investigations have been undertaken for two different interpenetrating polymer networks (IPNs) based on a model vinyl ester (VER, composed of bisphenol A diglycidyl ether dimethacrylate, bisGMA, in 30 wt % styrene) cured with azobis(isobutyronitrile) (AIBN) and an epox…
Reactions between [M(N(4)-macrocycle)](2+) (M = Zn(II) and Ni(II); macrocycle ligands are either CTH = d,l-5,5,7,12,12,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane or cyclam = 1,4, 8, 11-tetrazaazaciclotetradecane) and [M(CN)(6)](3-) (M = Fe(III) and Mn(III)) give rise to cyano-bridged assemblies with 1D linear cha…