Materials Literature
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Bilayer graphene (two coupled graphitic monolayers arranged according to Bernal stacking) is a two-dimensional gapless semiconductor with a peculiar electronic spectrum different from the Dirac spectrum in the monolayer material. In particular, the electronic Fermi line in each of its valleys has a strong $\mathbf{p}\…
A glass used to liquid‐phase sinter BaTiO 3 was developed and its properties were tested to determine the feasibility of using this glass to aid densification behavior. Glass was added to pure BaTiO 3 powder and pressed into dimpled pellets with glass contents varying from 4 to 20 vol%. The breakdown strength was meas…
Previous experiments showed that γ‐Al 2 O 3 ‐modified Al powder could continuously react with water and generate hydrogen at room temperature under atmospheric pressure. In this work, a possible physicochemical mechanism is proposed. It reveals that a passive oxide film on Al particle surfaces is hydrated in water. OH…
The effect of Li substitution for Mg and of Li-C co-substitution on the superconducting properties and crystal structure of MgB2 single crystals has been investigated. It has been found that hole doping with Li decreases the superconducting transition temperature Tc, but at a slower rate than electron doping with C or…
Glutaraldehyde has been used for several decades as an effective crosslinking agent for many applications including sample fixation for microscopy, enzyme and cell immobilization, and stabilization of protein crystals. Despite of its common use as a crosslinking agent, the mechanism and chemistry involved in glutarald…
We have performed the first experimental investigation of quantum interference corrections to the conductivity of a bilayer graphene structure. A negative magnetoresistance--a signature of weak localization--is observed at different carrier densities, including the electroneutrality region. It is very different, howev…
Two liquid chromatography techniques for single-walled carbon nanotube (SWNT) separation, size-exclusion chromatography (SEC), and ion-exchange chromatography (IEX) are combined to obtain small diameter semiconducting SWNTs with defined length and chirality. It is observed that these tubes elutes in the IEX separation…
Bacterial cellulose (BC) nanofibers were acetylated to enhance the properties of optically transparent composites of acrylic resin reinforced with the nanofibers. A series of BC nanofibers acetylated from degree-of-substitution (DS) 0 to 1.76 were obtained. X-ray diffraction profiles indicated that acetylation proceed…
Emerging complex functional materials often have atomic order limited to the nanoscale. Examples include nanoparticles, species encapsulated in mesoporous hosts, and bulk crystals with intrinsic nanoscale order. The powerful methods that we have for solving the atomic structure of bulk crystals fail for such materials…
The dependence of the optical properties of spherical gold nanoparticles on particle size and wavelength were analyzed theoretically using multipole scattering theory, where the complex refractive index of gold was corrected for the effect of a reduced mean free path of the conduction electrons in small particles. To…
Of rare-earth metal hexaoxotellurates(VI), only the structures of formula type RE2TeO6 are known so far. Diyttrium(III) hexaoxotellurate(VI), Y2TeO6, crystallizes isotypically with the orthorhombic La2TeO6-prototype structure in space group P212121. Single crystals were obtained by fusing a mixture of Y2O3 and TeO…
The application of time-dependent electric fields to a sample that exhibits dielectric loss results in the irreversible transfer of energy from the external field to the slow degrees of freedom in the material. These slow modes are coupled only weakly to the phonon bath and elevated fictive temperatures are thus assoc…
We introduce a scheme for the calculation of nonresonant hyper-Raman spectra of vitreous materials within a density-functional formulation. Hyper-Raman tensors are obtained through the application of finite electric fields and explicitly account for the nonlinear modulation of the dielectric susceptibility by longitud…
We report on an interlaboratory study on the precision and accuracy of determining dc soft magnetic properties, under the auspices of ASTM Committee A06 on Magnetic Properties. For certain quantities, the significant differences in the between-laboratory reproducibility results for high-permeability materials indicate…
Licht macht Gene munter: Die photochemische Steuerung der Genexpression dient zur Aufklärung biologischer Prozesse und zur Programmierung neuer biologischer Funktionen. Ein photoaktivierbares Molekül aktiviert die Proteinexpression in prokaryotischen Zellen bei Lichteinstrahlung (siehe Bild). Im speziellen Fall gelang…
The photoinduced energy and structural relaxation of aqueous iron(II)-tris-bipyridine ([FeII(bpy)3]2+), upon excitation into its singlet metal-to-ligand charge transfer (1MLCT) band, and the population of its short-lived (?0.6 ns) high-spin excited state have been characterized by combined ultrafast optical and X-ray…
We present fully atomistic molecular dynamics simulation results on a main-chain polymer, 1,4-polybutadiene, in the merging region of the α- and β-relaxations. A real-space analysis reveals the occurrence of localized motions ('β-like') in addition to the diffusive structural relaxation. A molecular approach provides…
Finite-size effects are analysed for the well-known BKS model of silica. Results are presented for thermodynamic as well as dynamic observables which play a key role in the analysis of the potential energy landscape. It turns out that, for the analysed temperature range ( T ≥3000 K), a system with only N = 99 particle…
The flow-induced microstructural distortions of dense colloidal dispersions under steady shearing are derived within a recent first-principles approach to the nonlinear rheology of colloidal fluids and glasses. The stationary structure factor is discussed to leading orders in shear rate . We find that shear affects th…
Corrosion resistance of aluminum alloys is related to the presence of a thin, passivating aluminum oxide film on the surface. In this paper, we perform first-principles quantum-mechanical calculations to provide atomic scale understanding of the initiation of corrosion in Al. Our results support the hypothesis that hy…