Materials Literature
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A simple method was used to assemble single-walled carbon nanotubes into indefinitely long ribbons and fibers. The processing consists of dispersing the nanotubes in surfactant solutions, recondensing the nanotubes in the flow of a polymer solution to form a nanotube mesh, and then collating this mesh to a nanotube fi…
The central problem in the determination of protein structures form x-ray diffraction dada (x-ray crystallography) corresponds to a phase retrieval problem with undersampled amplitude data. Algorithms for this problem that have an increased radius of convergence have the potential for reducing the amount of experiment…
The electronic structure and linear optical properties of the pyroborate A2B2O5 (A = Mg, Ca, Sr) compounds are reported here. These compounds, which crystallize with four formula units in the monoclinic space group P21/c, are modeled in terms of the cluster units (A2B2O5)2. The calculated electronic structures show th…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTPhotochemical Control of the Macroconformation of Polystyrene Using Azobenzene Side ChainsGilles Clavier, Faysal Ilhan, and Vincent M. RotelloView Author Information Department of Chemistry, University of Massachusetts, Amherst, Mas…
Directed synthesis of metal catalyzed carbon nanofibers and graphite encapsulated metal nanoparticles is demonstrated where the catalyst metal nanoparticles of Ni have been preformed prior to introduction into a reactive hydrocarbon growth environment. Control of the chemical environment by additives governs the type…
Fibril reconstruction process, that is, the nucleation and growth of mixed type I collagen fibril of shark and pig, progressed faster than that of the individual collagen species of shark or pig. The reconstructed mixed collagen fibril had a greater resistance to return to the solution or to melt into gelatin in compa…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTSingle-Bubble SonophotoluminescenceMuthupandian Ashokkumar and Franz GrieserView Author Information Particulate Fluids Processing Centre School of Chemistry, University of Melbourne Parkville, VIC, 3010, Australia. Cite this: J. Am. Chem. Soc. 2000, 122, 48, 12001–1200…
Spatially rhythmic (i.e., concentric ring and symmetric radial band) patterns appeared from droplets of collagen solutions during evaporation. A morphology diagram representing the pattern generation and bifurcation versus collagen concentration and evaporation time was determined. The pattern structures were examined…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTEfficient One-Pot Synthesis of Polysubstituted PyrrolesAlan R. Katritzky, Tian-Bao Huang, Michael V. Voronkov, Mingyi Wang, and Hartmuth KolbView Author Information Department of Chemistry, Center for Heterocyclic Compounds, University of Florida, Gainesville, Florida 32611-720…
Triblock nanospheres with hydroxylated polyisoprene (PHI) coronas, cross-linked poly(2-cinnamoyloxyethyl methacrylate) shells, and poly(acrylic acid) (PAA) cores were prepared following a method described previously. Equilibrating such nanospheres with a PdCl 2 solution in methanol enabled the loading of Pd 2+ into th…
Hybrid organic−inorganic materials derived from 3-glycidoxypropyltrimethoxysilane have been synthesized via sol−gel using BF 3 etherate as a catalyst of organic polymerization. Different amounts of BF 3 etherate have been used, from B/Si = 0.01 up to B/Si = 0.1, to prepare powder samples. The materials have been chara…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTNonlinear Optical Properties of Molecularly Bridged Gold Nanoparticle ArraysJames P. Novak, Louis C. Brousseau, Fredrick W. Vance, Robert C. Johnson, Buford I. Lemon, Joseph T. Hupp, and Daniel L. FeldheimView Author Information Department of Chemistry North Carolina S…
A series of alkanethiolate-passivated PbS nanoparticles were synthesized with varied feed ratios of the starting reactants, lead acetate and alkanethiols, and characterized by using a variety of spectroscopic and electrochemical techniques. Transmission electron microscopic studies revealed that, of all the samples pr…
Experiments determining the lifetime of excited electrons in crystalline copper reveal states which cannot be interpreted as Bloch states [S. Ogawa {\it et al.}, Phys. Rev. B {\bf 55}, 10869 (1997)]. In this article we propose a model which explains these states as transient excitonic states in metals. The physical ba…
Linear-scaling electronic-structure techniques, also called O(N) techniques, rely heavily on the multiplication of sparse matrices, where the sparsity arises from spatial cut-offs. In order to treat very large systems, the calculations must be run on parallel computers. We analyse the problem of parallelising the mult…
First-principles calculations are performed for electronic structures of two high pressure phases of solid selenium, $β$-Po and bcc. Our calculation reproduces well the pressure-induced phase transition from $β$-Po to bcc observed in selenium. The calculated transition pressure is 30 GPa lower than the observed one, b…
We present the theory of analytical Hartree-Fock gradients for periodic systems as implemented in the code CRYSTAL. We demonstrate how derivatives of the integrals can be computed with the McMurchie-Davidson algorithm. Highly accurate gradients with respect to nuclear coordinates are obtained for systems periodic in 0…
Poly(urethane-benzoxazine) films as novel polyurethane (PU)/phenolic resin composites were prepared by blending a benzoxazine monomer (Ba) and PU prepolymer that was synthesized from 2,4-tolylene diisocyanate (TDI) and polyethylene adipate polyol (MW ca. 1000) in 2 : 1 molar ratio. DSC of PU/Ba blend showed an exother…
Heat capacity of a quasi-one-dimensional organic conductor (DIMET) 2 I 3 has been measured by chopped-light ac calorimetry below room temperature. An anomaly due to a metal-insulator transition has been clearly detected around 40 K. The magnitude of the anomaly is analyzed through comparison with other Q1D conductors.…
The electronic and magnetic properties of double-layered Roddlesdon-Popper compounds, ${\mathrm{La}}_{1+2x}{\mathrm{Sr}}_{2\ensuremath{-}2x}{\mathrm{Mn}}_{2}{\mathrm{O}}_{7}$ with different doping x from 0.0 to 0.2 have been calculated using the full-potential linear muffin-tin orbital method. The total energies, band…