Materials Literature
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A fine Au powder, with a mean particle diameter of 4 nm, has been successfully fabricated. The crystalline structure of the 4 nm Au nanoparticles remains in fcc symmetry. No structural changes were found between 15 and 450 K. A crossover from a positive thermal expansion at low temperatures to a negative thermal expan…
A propanesulfonic acid-derivatized mesoporous SBA-15 catalyst was synthesized, characterized in terms of surface properties, and shown to have high selectivities for alcohol coupling to form ethers, specifically from methanol and isobutanol coupling to form methyl isobutyl ether with no detectable formation of butenes…
Micro-Raman scattering was used to characterize spinel CoFe 2 O 4 at high temperature up to 870 K and under an external magnetic field up to 6.0 kOe. It was found that the rapid increase in the linewidth of the Raman modes was related to the inter-site cation migration starting at ∼390 K. A red-shift of the Raman peak…
Abstract The glass transition temperature of the hard‐segment phase and the storage modulus of segmented polyurethane increased substantially in the presence of a small amount of tethered nano‐sized layered silicates from montmorillonite compared with their pristine state (by 44°C and by 2.8‐fold, respectively). Furth…
Ozonation of single-walled carbon nanotubes (O 3 -SWNTs) produces oxygenated functional groups, e.g., carboxylic acid, ester, and quinone moieties, which can be removed from the SWNT surface by heating at 600−800 °C. The annealed SWNTs appear to be pristine. The electrical resistance of the O 3 -SWNTs depends on the d…
Abstract During mechanical loading–unloading cycles shape‐memory alloys (SMA) are able to undergo large deformations without showing residual strains ( pseudoelasticity ) or recovering them through thermal cycles ( shape memory effect ). Motivated by stress‐induced solid phase transformations, these unique behaviours…
A recent theory that determines the properties of disordered solids as the solid accumulates damage is applied to the special case of fiber bundles with global load sharing and is shown to be exact in this case. The theory postulates that the probability of observing a given emergent damage state is obtained by maximi…
The resistivity, temperature, and magnetic field dependence of the anomalous Hall effect in a series of metallic Ga1-xMnxAs thin films with 0.015=
To obtain the probability distribution of 2D crack patterns in mesoscopic regions of a disordered solid, the formalism of Paper I requires that a functional form associating the crack patterns (or states) to their formation energy be developed. The crack states are here defined by an order parameter field representing…
This is the first of a series of three articles that treats fracture localization as a critical phenomenon. This first article establishes a statistical mechanics based on ensemble averages when fluctuations through time play no role in defining the ensemble. Ensembles are obtained by dividing a huge rock sample into…
The properties of the Hamiltonian developed in Paper II are studied showing that at a particular strain level a ``localization'' phase transition occurs characterized by the emergence of conjugate bands of coherently oriented cracks. The functional integration that yields the partition function is then performed analy…
We theoretically investigate the ground state properties of ferromagnetic metal/conjugated polymer interfaces. The work is partially motivated by recent experiments in which injection of spin polarized electrons from ferromagnetic contacts into thin films of conjugated polymers was reported. We use a one-dimensional n…
The state excited from the ground singlet of ${\mathrm{Co}}^{3+}$ in ${\mathrm{LaCoO}}_{3}$ was investigated by submillimeter-wave electron spin resonance (ESR) measurements. Clear ESR signals with zero-field splitting were observed above 20 K for the first time. The activation energy is estimated to be $\ensuremath{\…
The electron-phonon coupling strength in single-wall carbon nanotube (SWNT) bundles has been studied directly in the time-domain by femtosecond time-resolved photoelectron spectroscopy. We have measured the dependence of H(T_e,T_l), the rate of energy-transfer between the electronic system and the lattice as a functio…
Molecular electronic devices are the upmost destiny of the miniaturization trend of electronic components. Although not yet reproducible on large scale, molecular devices are since recently subject of intense studies both experimentally and theoretically, which agree in pointing out the extreme sensitivity of such dev…
Room-temperature drift mobilities of 4500 square centimeters per volt second for electrons and 3800 square centimeters per volt second for holes have been measured in high-purity single-crystal diamond grown using a chemical vapor deposition process. The low-field drift mobility values were determined by using the tim…
A series of electrochemically polymerizable Ni dithiolene complexes have been prepared and their electrochemical and spectroscopic properties have been characterized. Three thiophene-substituted complexes were anodically polymerized to give polymer films whose electrochemical properties correlated well with their pred…
The X-ray crystal structure has revealed two similar alpha/beta domains of aspartate racemase (AspR) from Pyrococcus horikoshii OT3, and identified a pseudo mirror-symmetric distribution of the residues around its active site [Liu et al. (2002) J. Mol. Biol. 319, 479-489]. Structural homology and functional similarity…
A simple triacetylide complex of chromium(III) is synthesized for use as a potential precursor to metal-dicarbide clusters. Reaction of Me(3)SiCCLi with [(Me(3)tacn)Cr(CF(3)SO(3))(3)] (Me(3)tacn = N,N',N"-trimethyl-1,4,7-triazacyclononane) in THF generates [(Me(3)tacn)Cr(CCSiMe(3))(3)], which subsequently reacts with…
In this study, the evolution of the flow stress for grain sizes ranging from about 16 to 2 μm under shear deformation was simulated using two-dimensional discrete dislocation dynamics. The analyses were confined to a single slip system and to the collective behaviour of a large number of edge dislocations, modelled as…