Materials Literature
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A combination of electrostatic interactions and covalent bonding is used to form films with low-molecular-weight chromophores by a layer-by-layer deposition process. Using a common, commercially available red dye, this deposition process results in noncentrosymmetric films (see scheme) that exhibit second-harmonic gen…
Mesoporous high-surface-area alumina was prepared by a modified aerogel procedure. Specific surface areas between 530-685 m(2)g(-1) were obtained after heat treatment at 500 degrees C. Nitrogen adsorption studies have shown that surface areas and pore characteristics change upon decomposition of aluminum hydroxide to…
The bisporphyrin host ZnH was synthesized, and its complexation with two aromatic diimide guest molecules, bis(pyridyl)naphthalenediimide NIN and bis(pyridyl)phenyldiimide PIN, was investigated by (1)H NMR and UV/Vis spectroscopy. The diimide guests were complexed simultaneously with both metalloporphyrins of the host…
Directed precipitation of silicic acid during the formation of diatom cell walls is promoted by polyamines (see picture) and peptides. These species-specific organic matrices, which direct the biomineralization process to amorphous SiO2, are accessible only after dissolution of the silica cell wall with hydrogen fluor…
An ambitious goal in the area of nanobiosciences is to combine the functionality and stability of nanostructured inorganic solids with the structural variety and the self-organizing abilities of biochemical molecules. How the ligand shell of nanoparticles needs to be built up to achieve a stable and specific conjugati…
Evaporation of ultrathin (1.3-10 nm nominal thickness) gold films onto quartz or mica leads to the formation of a layer of rather uniform gold islands on the transparent support. The morphology of ultrathin gold island films of various thicknesses was studied by using atomic force microscopy (AFM) and scanning electro…
A series of platinum (II) C empty set N empty set C complexes, [Pt(C empty set N empty set C) (L)] (HC empty set N empty set CH=2,6-diphenylpyridine (dppy); L=Ph(2)PB15C5 (1, B15C5=benzo[15]crown-5), Ph(2)PDMP (2, DMP=3,4-dimethoxyphenyl), pyCOA15C5 (3, A15C5=aza[15]crown-5), pyCON(CH(2)CH(2)OCH(3))(2) (4), pyC[triple…
Full-potential gradient corrected density functional calculations of the adsorption of potassium on the Ag(111) surface have been performed. The considered structures are Ag(111) (root 3 x root 3) R30degree-K and Ag(111) (2 x 2)-K. For the lower coverage, fcc, hcp and bridge site; and for the higher coverage all consi…
Building on an analogy with conformal invariance, local scale transformations consistent with dynamical scaling are constructed. Two types of local scale invariance are found which act as dynamical space-time symmetries of certain non-local free field theories. Physical applications include uniaxial Lifshitz points an…
Remarkable vapochromic effects are observed in a dinuclear platinum(II) complex, where changes in luminescence are facilitated in the presence of solvated organic molecules, such as acetonitrile and ethanol (see scheme).
Abstract Due to the increasing use of power electronics high frequency working voltages are occurring rather frequently. This means a very high stress for any kind of insulatation. This situation is further aggravated by decreasing dimensions due to miniaturization. Therefore this situation has to be taken into accoun…
The chemiluminescence generated from the reaction of a thermally stable phenylphosphate-substituted dioxetane Lumigen PPD at ambient temperature was studied in DMSO solution. The presence of trivalent metal ions Cr(3+), Ga(3+), Fe(3+) and Al(3+) was found to quench the resulting chemiluminescence dramatically. The sys…
The temperature dependence of electrical resistivity in LaSrNiO4 ± δ ceramics synthesized using various techniques and subjected to heat treatment is studied. The occurrence of a metal-semiconductor transition is shown to be accounted for by the Anderson carrier localization originating from the random arrangement of…
The effects of nitrogen postplasma treatment on the properties of a Cu/Ta/a-C:F structure were investigated. Interface reactions between Ta and a-C:F were also examined. A strong interaction between Ta and a-C:F at the interface and defluorination of a-C:F film occurred during Ta sputter deposition. Ta fluoride was ob…
Adhesil1e support treatments for the conservation of silk artifacts were evaluated by comparing the properlies and relative light stability of silk laminates and their components. Samples were prepared by adhering silk habutae, representing the artifact, to a silk or polyester crepeline support fabric with either Appr…
The influence of commercially available inhibitors on the absorption of hydrogen by steel (St 52, StE 460, StE 690, 42CrMo4) in 15% hydrochloric acid was studied. The pickling bath aged continuously due to the chemical reaction with oxidized steel sheets. The H+- and inhibitor concentration decreased with time. The in…
Abstract Clay minerals in early Jurassic sequences of shales, siltstones and sandstones deposited in non-marine, transitional and shallow marine environments have been examined by X-ray diffraction, electron microscopy and chemical analysis to study the relationship between clay minerals, their environment of depositi…
Doping nanocrystalline silicon ( nc -Si) films grown by laser ablation with gold leads to a considerable suppression of the nonradiative recombination of the charge carriers and excitons, an increase in the intensity and stability of the visible photoluminescence, and enhancement of the low-energy (1.5–1.6 eV) photolu…
From silica precursors we synthesized silica fillers in sol-gel reaction in the carboxylated acrylonitrile/butadiene rubber (XNBR). N-2-aminoethyl-3-aminopropyl-trimethoxysilane (DAMS) and tetraethoxysilane (TEOS) were used as fillers' precursors. It has been found that DAMS is a substance crosslinking XNBR. The netwo…
Diamond is a prototype mechanical material. Its hardness is greater than that of any other material. Its shear stiffness is greater than its bulk modulus, and the latter is greater than that of any other material. Its surface energy is greater than that of any other cubic crystal. The purpose of this manuscript is to…