Materials Literature
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Involatile OsO4! A tetrasubstituted olefin is immobilized on SiO2 and reacts with OsO4 to form a stable osmate(IV) ester (see scheme), which is a leak-proof heterogeneous catalyst for the cis-dihydroxylation of olefins.
Passivation of the metal surface by dendrons bearing a focal 4-pyridone functionality (the second-generation dendron is shown; C: gray, N: blue, O: red) allows controlled nucleation and growth of gold nanoclusters. The particle size is a direct function of the generation number of the dendritic ligands, with higher ge…
From the acid-catalyzed condensation of aryl aldehyde and pyrrole a new type of fused expanded porphyrins, N-fused pentaphyrins NFP5-Y (24 π, yellow) and NFP5-R (22 π, red) were obtained in total yields of 2–19 %. The two normal-type porphyrins are quantitatively interchanged through a redox reaction (see scheme). DDQ…
A surface anisotropy has been shown previously to be induced in thin films of photoreactive coumarin side-chain polymers by polarized UV illumination. Consequently, the resultant cross-linked polymer layers can be used as photoalignment layers for liquid crystal displays. Homogeneous alignment of a nematic liquid crys…
Abstract Description of Paper This paper discusses various mechanisms that can lead to the formation of iron sulfide scale downhole, techniques that can be used to prevent its formation and methods to remove it. Iron sulfide scale is present in oil and gas producing wells, water injection and supply wells. There are v…
Primary metallic or small-gap semiconducting nanotubes are tubes with band gaps that arise solely from breaking the bond symmetry due to curvature. We derive an analytic expression for these gaps by considering how a general symmetry breaking opens a gap in nanotubes with a well-defined chiral wrapping vector. This ap…
This paper draws attention to selected experiments on enzyme-catalyzed reactions that show convex Arrhenius plots, which are very rare, and points out that Tolman's interpretation of the activation energy places a fundamental model-independent constraint on any detailed explanation of these reactions. The analysis pre…
We study the adsorption of chlorine on the Ag(111) surface with full potential gradient corrected density functional calculations. When considering a root3 x root3 R30degree pattern, we find that the fcc hollow is the most favorable adsorption site. We obtain an Ag-Cl bond length of 2.62 Angstrom which is intermediate…
We have investigated the role of the stress-induced by the presence of the substrate in thin films of colossal magnetoresistive manganites on structural, resistive and magnetic properties. Because of the strong coupling between the small structural distortions related to the charge-ordering (CO) and the resistive prop…
Chiral recognition in organogels occurs in the coassembly of the chiral gelator 1 with the chiral guest molecule 2. The diastereomeric aggregates formed from (R,R)-2 with (R,R)-1 or (S,S)-1 were found to be truly different in structure and strength. Cooperativity makes a major contribution to the chiral recognition in…
Uniformly dispersed copper oxide nanoparticles in poly(vinyl alcohol) (CuO−PVA) have been synthesized by the sonochemical method. The properties of the as-prepared composite material are characterized by XRD, DSC, thermogravimetric analysis (TGA), TEM, and diffuse reflection spectroscopy (DRS). A band gap of 2.1 eV is…
Nanoparticles with high photoluminescence quantum yield have been recently considered as possible biolabels and as emitters in optoelectronic devices. Now gram amounts of nontoxic, chemically stable LaPO4:Ce,Tb nanocrystals (see picture) have been obtained in a coordinating solvent. These nanoparticles can be easily r…
The electrochemical behavior of a film of single-wall carbon nanotubes (SWNTs) functionalized with carboxylic acid groups was studied extensively on a glassy carbon (GC) electrode. One stable couple corresponding to the redox of the carboxylic acid group, which was supported by XPS and IR experiments, was observed. Th…
In this paper, we explore the optical properties of Ag nanoparticles chemically modified with alkanethiol self-assembled monolayers (SAMs) by measuring the localized surface plasmon resonance (LSPR) spectrum using UV−vis extinction spectroscopy. For all the experiments presented here, the Ag nanoparticles were fabrica…
The temporal shape evolution of CdSe quantum confined nanorods (quantum rods) in nonaqueous solvents with organometallic precursors was studied quantitatively and systematically. The experimental results revealed three distinguishable stages in the shape evolution. At high monomer concentrations, nanocrystals grow exc…
Spin dynamics of ceramic ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3}$ with $x=0,$ 0.05, and 0.15 and the relative ${\mathrm{Mn}}^{4+}$ concentration $c=0.18--0.22$ is investigated by measurements of the ac susceptibility and the relaxation of the thermoremanent magnetization (TRM). The ${\ensu…
A promising class of optical filters is introduced, based on diffraction at small apertures. The filters consist of straight pores with diameters in the micrometer regime and a length of up to one millimeter through a silicon wafer. In contrast to Bragg, Woods, or glass filters, the light is not transmitted in matter…
Fatigue-free and highly c-axis oriented Bi3.25La0.75Ti3O12 (BLT) thin films were grown on Pt/Ti/SiO2/Si(100) substrates using metalorganic solution decomposition. Films annealed above 500 °C were characterized by strong c-axis preferential growth with an in-plane alignment of grains. The BLT film capacitors with a Pt…
ZnS films were grown on Si (100) at high temperatures by pulsed laser deposition using a KrF excimer laser. The growth temperature was varied from 200 to 700 °C and all films were found to have a specific preferential orientation. With increasing Ts, growth rate decreased but the quality of the film improved. The high…
Dispersions of silica spheres (aerosil) in octylcyanobiphenyl (8CB) liquid crystal were investigated with deuteron NMR. For the lowest silica density dispersions, there is a field-induced liquid crystal alignment as the field anneals most elastic strains. Increasing the silica density, the molecular alignment is stabi…