Materials Literature
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We present a multigrid algorithm for self consistent solution of the Kohn-Sham equations in real space. The entire problem is discretized on a real space mesh with a high order finite difference representation. The resulting self consistent equations are solved on a heirarchy of grids of increasing resolution with a n…
We apply first principles calculations to study the opening of single-wall carbon nanotubes (SWNT's) by oxidation. We show that an oxygen rim can stabilize the edge of the open tube. The sublimation of CO$_2$ molecules from the rim with the subsequent closing of the tube changes from endothermic to exothermic as the t…
Open-system density functional theory may be formulated in terms of ensemble averages arising from interaction with a bath. The system is allowed to exchange particles with the bath and the states in the ensemble average are those corresponding to integer numbers of particles. The weights in the ensemble average are t…
Proximity-induced superconductivity in single-walled carbon nanotubes below 1 kelvin, both in a single tube 1 nanometer in diameter and in crystalline ropes containing about 100 nanotubes, was observed. The samples were suspended between two superconducting electrodes, permitting structural study in a transmission ele…
The microphase morphology of a polystyrene- block -polybutadiene- block -poly(ε-caprolactone) SBC triblock copolymer is studied through transmission electron microscopy. Even though crystallization of the PCL block takes place well below the PS glass transition, lamellar microphases and the formation of well-defined s…
Photodegradation of solvent-cast collagen type I films and photostabilization of collagen by vitamin E were studied. These films were exposed to polychromatic radiation from a medium-pressure mercury lamp or monochromatic radiation from the Okazaki Large Spectrograph (OLS). Changes in the molecular structure of collag…
We described in this work new glucose-persubstituted poly(amidoamine) dendrimers. The physicochemical properties of these new amphiphilic dendrimers were investigated in water, showing that these new amphiphilic dendrimers were able to solubilizate increasing quantities of hydrophobic compounds (pyrene or aromatic ket…
Reactions of HO(O)P(O t Bu) 2 with Al 2 Me 6 and [Al(O i Pr) 3 ] 4 gave the new molecular aluminum phosphate complexes [Me 2 AlO 2 P(O t Bu) 2 ] 2 ( 1 ) and [Al(O i Pr) 2 O 2 P(O t Bu) 2 ] 4 ( 2 ), respectively. In the solid state, 1 exists as a centrosymmetric dimer consisting of two four-coordinate Al centers bridge…
Poly(dl-lactide) (PLA) homopolymers and poly(dl-lactide-co-glycolide) (PLGA) copolymers were synthesized from their cyclic dimers, i.e. dl-lactide and glycolide, by ring-opening polymerization in the presence of catalyst stannous octoate and chain control agent lauryl alcohol. The effects of catalyst and chain control…
A series of nonionic sugar-based bolaamphiphiles having n -alkylene chain length of 9, 10, 11, 12, 13, 14, 16, or 18 carbon atoms, N,N ‘ -bis(2-deoxy- d -glucopyranosid-2-yl)alkane-1, n -dicarboxamide, 1( n ), have been synthesized in one step from commercially available glucosamine hydrochloride. Their self-assemblin…
Reaction of R 2 dbmH (R = H, Me, Et; dbmH is dibenzoylmethane) with MnCl 3 (generated in situ from MnCl 2 and MnO 4 - ) in MeCN yields the five-coordinate, square-pyramidal complexes [MnCl(R 2 dbm) 2 ] (R = H, 1; Me, 4; Et, 7 ). The same reaction with MnBr 2 yields [MnBr(R 2 dbm) 2 ] (R = H, 2; Me, 5; Et, 8 ). Slow hy…
Two new (dialkylamino)ethoxy-substituted poly( p -phenylene)s (PPP) have been prepared, poly[2,5-bis(3-{ N,N -diethylamino}-1-oxapropyl)-1,4-phenylene- alt -1,4-phenylene] (P−NEt 2 ) and poly[2,5-bis(3-{ N,N -dimethylamino}-1-oxapropyl)-1,4-phenylene- alt -1,4-phenylene] (P−NMe 2 ). These PPPs were synthesized via Pd-…
Angle resolved photoemission spectroscopy (ARPES) has been commonly applied to evaluate the shape of Fermi surfaces by employing simple criteria for the determination of the Fermi vector k_F parallel to the surface such as maximum photoemission intensity at the Fermi level or discontinuity in the momentum distribution…
At low temperatures, dynamics in amorphous silicon occurs through a sequence of discrete activated events that locally reorganize the topological network. Using the activation-relaxation technique, a data base containing over 8000 such events is generated, and the events are analyzed with respect to their energy barri…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTSuperior Fe-ZSM-5 Catalyst for Selective Catalytic Reduction of Nitric Oxide by AmmoniaRichard Q. Long and Ralph T. YangView Author Information Department of Chemical Engineering University of Michigan Ann Arbor, Michigan 48109-2136 Cite this: J. Am. Chem. Soc. 1999, 1…
The compartmental ligand H(2)L(A), containing an N(3)O(2) Schiff base and an O(2)O(3) crown like coordination site, has been prepared by reaction of 3,3'-(3-oxapentane-1,5-diyldioxy)bis(2-hydroxybenzaldehyde) with 1,5-diamino-3-azamethylpentane. The formation of a [1+1] macrocycle was inferred by IR, NMR, and mass spe…
The reduction of structural Fe affects many surface chemical properties of smectite clay minerals, including their hydration and interfacial forces. To expand our knowledge of these processes, Fourier transform infrared (FTIR) spectroscopy was used to investigate the effects of structural Fe oxidation state and hydrat…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTCharacterization of Poly(ethylene oxide)-block-poly(l-lactide) by HPLC and MALDI-TOF Mass SpectrometryHyunjung Lee, Wonmok Lee, Taihyun Chang, Siyoung Choi, Doosung Lee, Haining Ji, William K. Nonidez, and Jimmy W. MaysView Author Information Department of Chemistry and Polymer…
A new one-phase synthesis of thiol-functionalized platinum nanoparticles is presented. Using tetrahydrofuran as the solvent and lithium triethylborohydride (“superhydride”) as the reducing agent, platinum nanoparticles functionalized by octadecanethiol were prepared. Fourier transform infrared spectroscopy (FTIR), tun…
Many synthetic microspheres are spherical and symmetrical because of the thermodynamical limitations of the reaction systems. We developed modification techniques to prepare spherical microspheres with intrinsic unsymmetry, for example, a microsphere with both an anionic and a cationic part. The modification was perfo…