Materials Literature
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Properties such as the glass transition temperature ( T(g)) and the diffusion coefficient of ultrathin polymeric films are shown to depend on the dimensions of the system. In this work, a hard-sphere molecular dynamics methodology has been applied to simulate such systems. We investigate the influence that substrates…
We find a correlation between the dynamics of fluorescence intermittency and spectral diffusion in the spectroscopy of single CdSe nanocrystal quantum dots (QD). A statistical analysis of the data suggests two populations of blinking events: blinking followed by large spectral diffusion shifts and blinking with small…
Electrochemical characteristics of supercapacitors built from multiwalled carbon nanotubes electrodes have been investigated and correlated with microtexture and elemental composition of the materials. Capacitance has been estimated by cyclovoltammetry at different scan rates from 1 to 10 mV/s, galvanostatic discharge…
This contribution presents a systematic light scattering study of a series of boron oxide glasses which are characterized by different thermal histories. The thermal treatment was obtained by annealing the samples close to the glass transition temperature for times of several hours. Both low-frequency (0.1–30 cm−1) an…
We study the phase behavior of the Zwanzig model of suspensions of hard rods, allowing for polydispersity in the lengths of the rods. In spite of the simplified nature of the model (rods are restricted to lie along one of three orthogonal axes), the results agree qualitatively with experimental observations: the coexi…
Some new analytic results concerning the foam drainage equation are described. The temporal approach to the equilibrium profile of the foam is shown to be exponential, in agreement with numerical calculations. The effect of including the equilibrium distribution of the liquid fraction as an initial condition is discus…
The polymerization of solid acetylene under pressure has been studied by Fourier transform infrared (FTIR) spectroscopy. Controlled laser irradiation cycles and the employment of infrared sensors to measure the sample pressure, allowed to separate the photochemical and the pressure effect on the injection and on the e…
We have investigated with extensive Monte Carlo simulations in the isothermal isobaric ensemble a system of N=8192 elongated attractive-repulsive biaxial Gay–Berne (GB) particles. We have found uniaxial and biaxial nematic phases and a biaxial orthogonal smectic phase in this thermotropic model system.
Diffusion of a particle in the N-dimensional external potential which is periodic in one dimension and unbounded in the other N-1 dimensions is investigated. We find an analytical expression for the overdamped diffusion and study numerically the cases of moderate and low damping. We show that in the underdamped limit,…
The criteria for the existence of supersonic and multiple topological excitations (kinks) in the driven Frenkel-Kontorova model (a chain of atoms placed into an external periodic potential) with anharmonic (exponential) interatomic interactions are studied.
Geometric structures of three types of supramolecular aggregates composed of bis(phthalocyaninato)lutetium (Lu(Pc) 2 ) radicals are investigated by means of ESR measurements and theoretical calculations. The tetra-crown-substituted complex, Lu(CR 4 Pc)(Pc) (CR 4 Pc = tetra-15-crown-5 substituted Pc), forms an aggregat…
Polycrystalline single- and double-layer BaTiO 3 (BT) and SrTiO 3 (ST) films on flexible polymer films were synthesized by hydrothermal treatments of sol−gel amorphous titanium oxide films with M(OH) 2 (M = Ba, Sr) aqueous solutions from 60 to 150 °C. The amorphous titanium oxide films were prepared by a dip-coating m…
The length of alkyl chains attached to NLO chromophores exerts a critical control on their crystal structures and SHG capability. Systems with short as well as long alkyl chains form centrosymmetric lattices whereas those with chains of intermediate length, typically butyl chains, form noncentrosymmetric lattices and…
New enantiomerically pure binaphthyl derivatives bearing triphenylphosphine or phosphonate groups have been synthesized and used as building blocks to prepare the first optically active TTF and TCAQ dimers. Due to the restricted rotation of the two naphthalene rings, binaphthyl derivatives are ideal candidates to be u…
Serine hydroxymethyltransferase (SHMT) is a pyridoxal phosphate-dependent enzyme that catalyzes the reversible conversion of serine and tetrahydrofolate to glycine and methylenetetrahydrofolate. This reaction generates single carbon units for purine, thymidine, and methionine biosynthesis. The enzyme is a homotetramer…
The first hydrogen porous metallic membrane was a palladium tube with 1 mm wall thickness which T. Graham[1] used for measuring the hydrogen permeability at different temperatures. His experiments ...
Carbon nitride powder has been prepared by solid-state reaction between cyanuric chloride or its fluoro analogue and lithium nitride. The determined, by elemental analysis, atomic N/C ratio (1.33) in the synthesized material is entirely consistent with the C 3 N 4 stoichiometry. Combined material characterization data…
Heat capacities of the spin quantum number S = 1 / 2 two-dimensional Heisenberg antiferromagnet bis(2-amino-5-chloropyridinium) tetrabromocuprate(II) [(5CAP) 2 CuBr 4 ] crystal and its nonmagnetic analogue, the bis(2-amino-5-chloropyridinium) tetrabromozincate(II) [(5CAP) 2 ZnBr 4 ] crystal, were measured by adiabatic…
CdTe nanocrystals sequestered and passivated in an amorphous TiO 2 thin film matrix have been prepared by RF sputtering from a composite TiO 2 :CdTe target. The CdTe nanocrystal size and volume fraction increases from 15 to 40 nm and 2 to 20% respectively as the film thickness increases, typically from 0.05 to 0.25 µm…
Supramolecular enantiodifferentiating photoisomerization of (Z)-cyclooctene (1Z) to the chiral (E)-isomer (1E) via inclusion and sensitization by modified alpha-, beta-, and/or gamma-cyclodextrin derivatives, possessing benzoate (2a, 3a, 4a), isomeric phthalates (3b-d), and tethered benzamide (3e) chromophores, has be…