Materials Literature
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We describe a two-step conversion of C-alkylated zinc chlorins to zinc oxochlorins wherein the keto group is located in the reduced ring (17-position) of the macrocycle. The transformation proceeds by hydroxylation upon exposure to alumina followed by dehydrogenation with DDQ. The reactions are compatible with ethyne,…
An efficient procedure is described for catalyst recycling and easy product isolation in alkene epoxidation with hydrogen peroxide catalyzed by water-soluble iron(III) porphyrins in environmentally benign and ambient temperature ionic liquids.
The electronic absorption spectra of the bis(porphyrin) sandwich complexes of the metals Zr, Ce, and Th are studied with time-dependent density functional theory (TDDFT). A ground-state electronic structure analysis reveals that the highest occupied one-electron levels are, as expected, composed of the porphyrin a(1u)…
Ortho-carborane molecules have been inserted into single walled carbon nanotubes (SWNTs) and imaged directly by high resolution transmission electron microscopy (HRTEM); both discrete molecules and 'zig-zag' 1D chains of o-carborane 'petit pois' were observed to pack into the tubule capillaries.
The crystal structures of M(C(8)H(4)O(4))(H(2)O)(2), M = Mg, Mn, Fe and Co, have been determined by applying Monte Carlo simulated annealing techniques to synchrotron powder diffraction data and refined by the Rietveld method using both synchrotron and laboratory powder data. These isostructural compounds crystallize…
Abstract Clays are the most complicated objects in quantitative mineral analysis of sedimentary rocks. Complex quantitative analysis of clays comprises four major steps: measuring bulk quantities, quantifying the mixed layering, determining the three-dimensional organization, and measuring the particle size. Computeri…
Composite $({\mathrm{La}}_{0.67}{\mathrm{Ca}}_{0.33}{\mathrm{MnO}}_{3}{)}_{1\ensuremath{-}x}:(\mathrm{MgO}{)}_{x}$ films were prepared by metalorganic aerosol deposition on a (100)MgO substrate for different concentrations of the (MgO) phase $(0<~x<~0.8).$ At $x\ensuremath{\approx}0.3$ a percolation threshold in…
The hydrophobic channels in the structure of the dipeptide L-alanyl-L-valine act as supramolecular hosts for organic solvent molecules. In a series of data collections, it is demonstrated that small molecules like acetonitrile, methanol and acetone can be removed from the channels by drying without impairing the struc…
The tensile deformation behavior of poly(1-butene) and two of its ethylene copoloymers was studied at room temperature. This was done by investigating true stress−strain curves at constant strain rates, elastic recovery properties, and in-situ WAXS patterns during the deformation process. All samples showed a common r…
The structural chemistry of nanoscale materials encapsulated within single-walled carbon nanotubes (SWNTs) is reviewed. SWNTs form atomically thin channels within a restricted diameter range, and their internal van der Waals surfaces regulate the growth behavior of encapsulated crystals in a precise fashion, leading t…
We report the catalyst-free horizontal growth of carbon nanotubes on the Si face of hexagonal silicon carbide (6H-SiC) at temperatures above 1500 °C. These nanotubes are single walled with a very narrow distribution of diameters. Nanotubes tend to follow the atomic structure of the surface, leading to preferential ori…
BACKGROUND: Naked DNA and standard vectors have previously been used for gene delivery from implantable carrier matrices with great potential for gene therapeutic assistance of wound healing or tissue engineering. We have previously developed copolymer-protected gene vectors which are inert towards opsonization. Here…
Stable hollow silica microspheres were synthesized by a solgel method in nonionic W/O emulsion; the mesoporous shell wall of the spheres could have potential applications as controlled release capsules for drugs, dyes, cosmetics and inks, artificial cells, catalysts, and fillers.
If the full scientific and technological potential of mesostructured materials is to be achieved, systems with continuous domains in the form of single crystals or films must be prepared. Here we report a reliable and facile system for making large single-crystal particles of chalcogenido mesostructured materials with…
In this work, the use of a spinning disk reactor as a unit for a reaction−precipitation process is investigated. An experimental study is reported concerning the precipitation of barium sulfate from aqueous solutions at 25 °C on a spinning disk of 0.5 m in diameter. At a rotational speed higher than 900 rpm, spontaneo…
Interfering electrons in a mesoscopic ring are irradiated with both classical and nonclassical microwaves. The average intensity of the charges is calculated as a function of time and it is found that it depends on the nature of the irradiating electromagnetic field. For various quantum states of the microwaves, the e…
Using density functional methods we calculated structural and electronic properties of bulk chloroform and bromoform intercalated C60, C60 2CHX3 (X=Cl,Br). Both compounds are narrow band insulator materials with a gap between valence and conduction bands larger than 1 eV. The calculated widths of the valence and condu…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTUnique Morphology of Poly(ethylene succinate)/Poly(ethylene oxide) BlendsZhaobin Qiu, Takayuki Ikehara, and Toshio NishiView Author Information Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1, Ho…
The solid oxide fuel cell (SOFC) is a simple electrochemical device that operates at 1000°C, and is capable of converting the chemical energy in natural gas fuel to AC electric power at approximately 45% efficiency (net AC/LHV) when operating in a system at atmospheric pressure. Since the SOFC exhaust gas has a temper…
The magnetoconductive properties of ultrathin Pb films deposited on Si(111) are measured and compared with density-functional electronic band-structure calculations on two-dimensional, free-standing, 1 to 8 monolayers thick Pb(111) slabs. A description with free-standing slabs is possible because it turned out that th…