Materials Literature
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Transparent alumina gels have been prepared with a simple precursor system, aluminum tri- sec -butoxide−2,4-pentanedione−2-propanol−nitric acid, at optimal acacH/ASB mole ratios of 0.3−0.4. The specific surface areas ( S BET ) of the prepared gels are in the range 552−560 m 2 /g after calcination at 400 °C for 2 h. It…
Decane has been used as swelling agent to enlarge the pore size of pure silica MCM-41 materials. The synthesis conditions such as the swelling agent/surfactant molar ratio, the adding sequence of swelling agent, etc., have been studied. The role of decane and the effect of crystallization time and temperature on the s…
The potential- and coverage-dependent infrared absorption spectroscopy (IRAS) of linearly bound CO on single-phase polycrystalline arc-melted Pt, PtRu(1/1), PtRu(8/2), PtOs(8/2), PtRuOs(8/1/1), PtRuOs(65/25/10), and Ru electrodes in 0.5 M H 2 SO 4 are correlated with the potential-dependent X-ray photoelectron spectro…
We reconsider the exponents s and μ that characterize the behaviors of the viscosity and the elastic modulus near the Sol−Gel transition. This is done by studying the dynamics of the elastic chain that connects neighboring nodes. We assume that the characteristic time for the latter is the same as for the whole cluste…
We study analytically kinetics of an elementary bimolecular reaction scheme of the Langmuir-Hinshelwood type taking place on a d-dimensional catalytic substrate. We propose a general approach which takes into account explicitly the influence of spatial correlations on the time evolution of particles mean densities and…
A number of recent studies have explored the energetics of intermediate-sized clusters, such as small fullerenes. For example, the isomer energies of C 20 have proven difficult to ascertain as different theoretical methods give widely varying results. For cluster sizes around 20−30 atoms, it is not immediately clear w…
Elastin-mimetic peptide polymers have been synthesized, and the morphological properties of fabricated small diameter fibers and nonwoven fabrics have been characterized. An 81 kDa recombinant protein based upon the repeating elastomeric peptide sequence of elastin (Val-Pro-Gly-Val-Gly) 4 (Val-Pro-Gly-Lys-Gly) was obt…
We provide a wet chemical approach for organizing randomly tangled single-walled carbon nanotubes (SWCNTs) on gold surfaces. The as-grown nanotubes were first chemically cut into short pipes and thiol-derivatized at the open ends. The ordered assembly of SWCNTs was made by their spontaneous chemical adsorption to gold…
Microstructured particles were synthesized by growing colloidal crystals in aqueous droplets suspended on fluorinated oil. The droplets template highly ordered and smooth particle assemblies, which diffract light and have remarkable structural stability. The method allows control of particle size and shape from sphere…
We measured the two-photon absorption (TPA) cross sections inside (beta) -BBO crystal during UV harmonic generation. We found that the 2-photon absorption is dominating the absorption effect inside the BBO crystal during UV harmonic generation. Both 2 UV photons and 1 UV photon + 1 fundamental photon absorption cross…
A stereoselective synthesis of 11Z-retinal 2, which is the chromophore of visual pigment (rhodopsin), was accomplished from the beta-ionylideneacetaldehyde-tricarbonyliron complex 3. The Peterson reaction of 3 using ethyl trimethylsilylacetate smoothly proceeded to afford predominantly the Z-ester 6. Transformation of…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTCrystallization-Induced Morphological Changes of a Poly(l-lactide)/Poly(oxyethylene) Diblock Copolymer from Sphere to Band via Disk: A Novel Macromolecular Self-Organization Process from Core−Shell Nanoparticles on SurfaceTomoko Fuj…
A poly[(R)-3-hydroxybutyrate] (P(3HB))-degrading marine bacterium (strain NK-1, JCM10458) was isolated from the Pacific Ocean deep-sea floor (1165 m in depth) in Japan. The organism was a motile and Gram negative, aerobic, and rod-shaped bacterium, and its DNA had a guanine-plus-cytosine content of 57.7 mol%. On the b…
Orotidine 5'-monophosphate decarboxylase (ODCase) catalyzes the decarboxylation of orotidine 5'-monophosphate, the last step in the de novo synthesis of uridine 5'-monophosphate. ODCase is a very proficient enzyme [Radzicka, A., and Wolfenden, R. (1995) Science 267, 90-93], enhancing the reaction rate by a factor of 1…
The structure buildup in hyperbranched polyesters from 2,2-bis(hydroxymethyl)propionic acid (bis-MPA) was studied experimentally. Bis-MPA and its dendritic trimer were both polymerized in bulk using acid catalyst. The fractions of terminal, dendritic, and linear repeating units were monitored by 13 C NMR during the co…
The magnetic susceptibility chi and specific heat C versus temperature T of the spin-1/2 antiferromagnetic alternating-exchange (J1 and J2) Heisenberg chain are studied for the entire range 0 \leq alpha \leq 1 of the alternation parameter alpha = J2/J1. For the uniform chain (alpha = 1), detailed comparisons of the hi…
Disilazane reagents of type HN(SiR 1 R 2 2 ) 2 carrying organic substituents R 1,2 = H, Me, Ph, n -Bu, n -Oct, Vin (Vin = vinyl) of varying longitudinal and lateral extension are reacted with high quality MCM-41 samples of different pore sizes, i.e., effective pore diameters of 2.8 and 3.8 nm according to the BJH pore…
Numerous molecular compounds in which a paramagnetic Ln(III) ion is in interaction with a second spin carrier such as a transition metal ion or an organic radical have been described. However, except for the isotropic Gd(III) ion, very little is known concerning the nature ( ferro - or antiferromagnetic ) and mechanis…
We describe the preparation and photophysical characterization of two model compounds designed to test a new approach for the quantitative determination of Fluorescence Resonance Energy Transfer (FRET) in biological systems. The method enables modulation of FRET by exploiting the unique reversible spectral properties…
Computer simulations of a simple model of liquid crystals confined between parallel walls have been used to investigate the properties of nematic wetting films and the planar nematic–isotropic interface. Comparison is made with the theoretical predictions of Onsager’s density-functional theory, obtained by numerical m…