Materials Literature
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Of 140 newly synthesized chalcone-analogous materials, 56 specimens were observed to be efficient for nonlinear optical second harmonic generation (SHG). The SHG efficiency of 3-(4-chlorophenyl)-1-(3-pyridyl)-2-propen-1-one is discussed on the basis of crystal structure and MO calculation. In this crystal, molecules a…
Various synthetic protocols were used to prepare several classes of polysiloxane–silica filler systems. The structures of these fillers and their interactions with the polysiloxane matrices were studied using small-angle X-ray and neutron scattering. In addition, the mechanical properties of the composites were charac…
A general neural approach to magnetic hysteresis modeling is proposed. The general memory storage properties of systems with rate independent hysteresis are outlined. Thus, it is shown how it is possible to build a neural hysteresis model based on feed-forward neural networks (NN's) which fulfills these properties. Th…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTPicosecond Molecular Switch Based on Bidirectional Inhibition of Photoinduced Electron Transfer Using Photogenerated Electric FieldsDavid Gosztola, Mark P. Niemczyk, and Michael R. WasielewskiView Author Information Chemistry Division, Argonne National Laboratory Argon…
The formation of an anisotropic gel—a member of a new class of gel—is described. A structure is proposed for the liquid-crystalline gel (see also the cover of this issue), which was formed by the gelation of a room-temperature nematic liquid crystal, achieved by the self-aggregation of low-molecular-weight molecules t…
The antiferroelectric to ferroelectric phase transition in NaNbO3 was investigated by Raman scattering between 295 and 10 K. The transition occurs at 185 K on cooling and the antiferroelectric and ferroelectric phases coexist at low temperature. The transition occurs at 210 K on heating and the relatively large hyster…
Abstract The interface between plastic and wood fibers strongly influences the mechanical properties of a plastic/wood‐fiber composite. This paper presents a means for evaluating the effectiveness of surface treatment on the wood‐fibers in the PVC/wood‐fiber composites by investigating the adhesion between PVC and lam…
Guided-mode resonant grating filters have numerous applications. However, in weakly modulated gratings designed for use at normal incidence, the filtering resonance of these subwavelength-period devices splits for angles of incidence that are even slightly off normal incidence. Strongly modulated gratings are designed…
New strategies are reported for assembling Au nanoparticles into coupled 1D arrays. The mehods employ porous filtration membranes as templates to entrap and align particles along the long axis of the pores. Following alignment, nanoparticles were linked by 1,6-hexanedithiol to make shorter linear nanoparticle arrays (…
Extension of the surface sol-gel process to form molecularly alternate metal oxide/polymer films is reported. The Figure is a schematic illustration of the chemical structure of TiO2/poly(acrylic acid) multilayers grown using this method. It is demonstrated that films can also be assembled using aluminum, zirconium, n…
Carbon formed from CO in CO 2 at around 500 °C deposited as nanotubes and encapsulating carbons on a supported Ni catalyst without H 2 or as filaments if H 2 was present. A thermodynamic model explains how hydrogen in low concentrations controls filament morphology and why equilibrium is shifted from that for graphite…
The syntheses, crystal structures, and physical properties of the series of radical salts made with bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF or ET) and monosubstituted α-Keggin polyoxoanions of formula [XZ(H 2 O)M 11 O 39 ] 5 - (XZM 11 = Si IV Fe III Mo 11, Si IV Cr III W 11, P V Co II W 11, P V Ni II W 11, P V…
The origin of the long-term gelation of clay suspensions was recently questioned. We have investigated this problem by looking at the chemical stability of the laponite solid particles as a function of the preparation, the long-term storage, and the age of the suspensions. Under ambient atmosphere, ${\mathrm{Mg}}^{2+}…
Excited-state energy migration among a collection of pigments forms the basis for natural light-harvesting processes and synthetic molecular photonic devices. The rational design of efficient energy-transfer devices requires the ability to analyze the expected performance characteristics of target molecular architectu…
The Hall resistivity ${\ensuremath{\rho}}_{H}$ and magnetoresistance of ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3}$ ${(T}_{c}=265$ K) have been measured at temperatures to 360 K in fields $H$ to 14 T. By comparing ${\ensuremath{\rho}}_{H}$ with the magnetization $M$, we have extracted the ano…
The palladium-catalyzed amination of aryl halides, in conjunction with an orthogonal protective group scheme, forms the basis of two routes to oligoaniline precursors. One method consists of a bidirectional chain growth from a symmetric core piece, whereas the other involves a divergent−convergent synthesis of nonsymm…
Chemical control over the size of nanoparticles is a prerequisite for their application. The synthesis of protective polymers having cyano or mercapto groups (e.g., MMS-NVP, see Figure) is reported, together with the influence of these polymers on the size and size distribution of gold nanoparticles synthesized by KBH…
Electrooptical and structural studies on self-assembled films composed of CdSe nanoparticles, poly( p -phenylene vinylene) (PPV), and different nonconjugated polyelectrolytes are reported. It is demonstrated by optical spectroscopy and X-ray reflectivity measurements that CdSe nanoparticles and PPV can successfully be…
Molecular dynamics (MD) simulations are used to study the static and dynamic properties of 2:1 layered silicates ion exchanged with alkyl-ammonium surfactants. These systems are in the form of oligomeric alkanes grafted by cationic groups on atomically smooth crystalline layers 10 Å thick and several microns wide. The…
A survey is given on recent research on “metal dusting” i.e. a catastrophic carburization or rather graphitization of metals and alloys occuring in carbonaceous atmospheres at carbon activities aC>1. The thermodynamics are explained, the mechanisms for iron, low and high alloy steels, nickel and Ni-base alloys are des…