Materials Literature
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DNA and RNA polymerases use divalent metal ions for catalysis. Crystal structures of several polymerases reveal that two acidic residues are involved in coordinating two metal ions at the catalytic centre. Bacteriophage RNA polymerases contain a highly conserved C-terminus with the carboxylate positioned near the acti…
The luminescence decay kinetics of homogeneously and delta-doped ZnS:Mn thin film phosphors was investigated. A quantitative model based on the hopping model of energy transfer theory was developed to described the concentration quenching phenomenon in ZnS:Mn. The model predicted the dependence of the energy transfer…
The presence of a parasitic surface film of 80 nm thickness has been observed by x-ray reflectivity on the top of some p+ type porous silicon layers, related to a contamination of the substrate. After testing several methods to clean the substrate and to avoid this film, it was found that a 300 °C thermal annealing of…
Electrode processes at redox electrodes consist of mass transport to and from the electrode|electrolyte interface and of charge transfer across this interface. At n-type semiconductor electrodes, charge transfer may involve either direct exchange of conduction band electrons or direct exchange of valence band holes, a…
Analytical description of photoelectron and Auger-electron transport in solids requires values of the transport cross sections ${\ensuremath{\sigma}}_{\mathrm{tr}}$ for electron energies between 50 and 2000 eV. An analytical formula is proposed to provide needed values of ${\ensuremath{\sigma}}_{\mathrm{tr}}$ for ener…
We have re-investigated the well-studied hydrogen covered Si(100) surface using high resolution electron energy loss spectroscopy (HREELS) with a spectral resolution down to 13 cm1, representing an improvement by a factor of 3–4 compared to earlier work. For the first time in HREELS, it has been possible to clearly di…
A detailed study of coupled porous silicon (PS) microcavities (PSM's) is reported. The samples are investigated by room temperature photoluminescence and reflectivity. A splitting of the eigenmodes of the coupled cavity structure is observed, as well as a difference between the intensities of the cavity peaks related…
The dielectric behavior of pulsed laser deposited ferroelectric (Pb1−xLax)(Zr0.65Ti0.35)O3 films (PLZT x/65/35, x=0–9.75 at. %) has been studied experimentally. Epitaxial stoichiometric PLZT films were formed on a pulsed laser deposited layer of La0.5Sr0.5CoO3 (LSCO) on MgO (100) single-crystal substrates. The dielect…
The stability of plasma-polymerized allylamine films with autoclaving sterilization cycles was investigated. Polymerized films were deposited under pulsed plasma conditions using two different duty cycles to provide surfaces having different initial amino group concentrations. The film properties were analyzed by XPS…
Polymer layered silicates form an important class of nanocomposite materials. These structures may be formed by annealing layered silicate particles, whose surfaces have been chemically modified to render them organophilic, with a polymer melt. During intercalation, polymer molecules leave the bulk melt and enter the…
It is shown that the fundamental gauge-symmetry constraints superimposed on the admissible form of the exchange-correlation energy functional lead to the generalized local force theorem for small nonuniform rotations of the spin magnetic moments near equilibrium. The theorem suggests that the magnetic interactions res…
We have studied the effect of crystalline size and surface roughness on Raman intensity for PbS nanocrystalline semiconductors of different crystalline sizes prepared by an electrochemical route. Rutherford back scattering spectroscopy provides the estimation of surface roughness, thickness, and composition of the PbS…
A silver island film was thermally deposited on the top of an azobenzene self-assembled monolayer on gold, yielding a SERS-active system possessing a “sandwiched” structure of Ag|R 1 −Azo−R 2 S−|Au. For the first time, the positions of the Azo groups were controlled by using azobenzenealkanethiols with different termi…
Magnetic properties of REMe 0.5 Mn 0.5 O 3 with Me = Ni and Co are investigated for a series of rare earth (RE) elements. In both systems with Me = Ni and Co, the Curie temperature ( T C ), below which the magnetic moments of Me 2+ and Mn 4+ allign ferromagnetically, decreases remarkably as RE goes from La to heavier…
We track individual defects in the microdomain patterns of cylinder-forming polystyrene-block-polymethylmethacrylate films with atomic force microscopy to elucidate the evolution of diblock domain topology during annealing. This evolution takes place through relinking, joining, clustering, and annihilation of defects.…
We have examined the phase equilibrium and thermoelectric properties of Co1−xFexSb3 ternary system up to high iron context x=0.40. Traces of Sb were observed in the hot-pressed samples with x⩾0.06, and FeSb2 (Fe0.73Co0.27Sb2) compound with marcasite structure was also observed in the samples with x⩾0.25 by x-ray diffr…
The resistivity $\ensuremath{\rho}(T)$ and magnetoresistance (MR) $(\ensuremath{\Delta}\ensuremath{\rho}/\ensuremath{\rho})$ of an entangled single-wall carbon-nanotube network are investigated. The temperature dependence of the resistivity shows a negative $d\ensuremath{\rho}/dT$ from $T=4.3--300 \mathrm{K}$ with no…
The results of a cutback measurement of a glass-ceramic optical waveguide with single-mode fiber geometry have demonstrated that sub decibels per kilometer losses can be achieved. Difference spectra show that the limit of intrinsic scattering in these two-phase structures ought to be tens of decibels per kilometer.
We develop an analytic integral equation theory for treating polymer-induced effects on the structure and thermodynamics of dilute suspensions of hard spheres. Results are presented for the potential of mean force, free energy of insertion per particle into a polymer solution, and the second virial coefficient between…
Polymer molecules intercalated between the layers of calcium silicate hydrate during its precipitation from aqueous solution expand the interlayer dimension. Alteration in the structure by changes in bulk composition allows polymers of different charge to be intercalated. The polymer chains may adopt an extended linea…