Materials Literature
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Magneto-transport measurements of ferromagnetic MnAs epilayers grown by molecular beam epitaxy reveal the presence of both positive and negative charge carriers. Electrical transport at high temperatures is dominated by holes, and at low temperatures by electrons. We also observe distinct changes in the magnetoresista…
Core−shell composite materials consisting of a silica core and a polystyrene (PS) shell were prepared by colloidal assembly of PS nanospheres onto silica microspheres. The assembly process was controlled by specific chemical (amine−aldehyde) or biochemical (avidin−biotin) interactions between the nanospheres and micro…
We report here on the influence of changes in the solution salt concentration on the structure of multilayers of weak polyelectrolytes. For poly(acrylic acid) (PAA) and poly(allylamine) (PAH) multilayers assembled by the layer-by-layer process in the presence of sodium chloride, washing with pure water after depositio…
Established bond-valence parameter tables rely on the assumption that the bond-valence sum of a central atom is fully determined by interactions to atoms in its first coordination shell. In this work the influence of higher coordination shells is tested in detail for bonds between lithium and oxygen. It is demonstrate…
The amino acid sequence of the heavy chain of Bombyx mori silk fibroin was derived from the gene sequence. The 5,263-residue (391-kDa) polypeptide chain comprises 12 low-complexity "crystalline" domains made up of Gly-X repeats and covering 94% of the sequence; X is Ala in 65%, Ser in 23%, and Tyr in 9% of the repeats…
We present two models for the stepwise copolymerization between a three-functional monomer A 3 and a bifunctional monomer B 2 where both intramolecular reaction and different intrinsic reactivities of reactive sites are present. The difference in reactivities may be either on the A sites or the B sites, leading to two…
The temperature and time dependence of electric-field-induced motion of thermally generated protons in 20 nm amorphous ${\mathrm{SiO}}_{2}$ films has been investigated. The short-time behavior is found to involve an activation energy of \ensuremath{\sim}0.38 eV and a hopping distance of \ensuremath{\sim}0.55 nm. The a…
Acidity constants (in terms of K(i) values) can be fine-tuned, their values can be pushed to extremes, and their location can be placed either at the basic or acidic range of the pH scale, by tailoring intra-cage properties of SiO(2) sol--gel materials with surfactants. With the entrapped "solid-state pseudomicelles",…
We investigate the role of static disorder on defect energetics on examples of interstitial oxygen atoms in amorphous $(a)\ensuremath{-}{\mathrm{SiO}}_{2}.$ We generate representative amorphous structures using molecular dynamics with empirical potentials and refine them using the periodic plane-wave density-functiona…
Rh(III) porphyrin complexes with bridging hydrazine and substituted hydrazine ligands were characterized in solution by (1)H NMR spectroscopy and in the solid state by X-ray diffraction. Addition of further ligand to these species afforded 1:1 complexes in which methylhydrazine and N,N-dimethylhydrazine preferentially…
A series of 1,3,5-phenylene-based rigid dendritic porphyrins were synthesized by Suzuki coupling between a porphyrin core and dendron units. The intramolecular energy transfer was studied by absorption and fluorescence spectroscopies. The encapsulation of the porphyrin core within the 1,3,5-phenylene dendron units was…
CO adsorption on Pd atoms deposited on MgO(100) thin films has been studied by means of thermal desorption (TDS) and Fourier transform infrared (FTIR) spectroscopies. CO desorbs from the adsorbed Pd atoms at a temperature of about 250 K, which corresponds to a binding energy, E(b), of about 0.7 +/- 0.1 eV. FTIR spectr…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTMechanism of Hydrogen Sorption in Single-Walled Carbon NanotubesHansong Cheng, Guido P. Pez, and Alan C. CooperView Author Information Computational Modeling Center and Corporate Science and Technology Center, Air Products and Chemicals, Inc. 7201 Hamilton Boulevard, A…
We have observed magnetic circular dichroism (MCD) in the soft x-ray absorption spectra of the semiconducting ferromagnet ${\mathrm{CdCr}}_{2}{\mathrm{Se}}_{4}$ and the metallic ferromagnets ${\mathrm{CuCr}}_{2}{\mathrm{S}}_{4}$ and ${\mathrm{CuCr}}_{2}{\mathrm{Se}}_{4}.$ The Cr $2p$ x-ray absorption and MCD spectra s…
An attempt was made to encapsulate nickel into the cavity of the carbon nanotubes, which were prepared by the pyrolytic carbon deposition on the nanochannels of anodic aluminum oxide film. For nickel loading, the MOCVD (metal organic chemical vapor deposition) method using nickelocene was applied to the carbon-coated…
The radio-frequency-induced plasma polymerization of allylamine has been investigated in the plasma-gas phase by mass spectrometry and at the plasma−solid interface by means of an ion flux probe and a quartz mass balance. The surface chemistry of the deposits has been determined by X-ray photoelectron spectroscopy. Th…
Barnacle cement is an underwater adhesive that is used for permanent settlement, and is an insoluble protein complex. A method for rendering soluble the cement of Megabalanus rosa has been developed, and three major proteins have been identified in a previous study. To survey the M. rosa cement proteins in a lower mol…
When determining crystal structures of organic molecular materials from high-resolution powder diffraction data, the key step is the generation of reliable trial structures for final refinement. The subject of the study reported here is the pharmaceutical material anhydrous theophylline (3,7-dihydro-1,3-dimethyl-1 H -…
The magnetic anisotropy of the cyclic octanuclear Fe(III) cluster [Cs subsetFe(8)[N(CH(2)CH(2)O)(3)](8)]Cl was investigated. Based on a spin Hamiltonian formalism and the consequent use of all symmetries, the magnetic anisotropy could be calculated exactly to first order, i.e., in the strong exchange limit. Experiment…
We find that in the presence of an electric field there is an attractive intergrain interaction in superconductors which is small. When charge on the ball is permitted to vary with the ball radius, very large balls can be formed. The pairing energy makes the ball compact and hence reduces the size of the ball compared…