Materials Literature
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The novel, Mn-substituted undecatungstosilicate [(β2-SiW11MnO38OH)3]15- (1) has been characterized by IR spectroscopy, elemental analysis, and single-crystal X-ray diffraction. Anion 1 is composed of three [β2-SiW11MnO38OH]5- fragments linked via three Mn−O−W (145(1)°) bridges leading to a triangular, chiral entity. T…
Hyperbranched polyisobutylenes (PIBs) have been synthesized by carbocationic copolymerization of an inimer ( ini tiator-mono mer, IM ) and isobutylene (IB). The IM used was 4-(2-methoxyisopropyl)styrene ( p -methoxycumylstyrene, pMeOCumSt), in conjunction with TiCl 4 as a co-initiator in methylcyclohexane (MeCHx)/meth…
Dense, crack-free, and homogeneous nanocrystalline (RE 2 O 3 ) 0.08 (ZrO 2 ) 0.92 (RE = Sc, Y) thin films (≈0.58-μm thick) on monocrystalline silicon (100) wafers were fabricated by a simple sol−gel spin-coating method under reduced annealing temperature and were characterized by X-ray diffraction (XRD), scanning elec…
The polarity of polyelectrolyte (PE) multilayer films is investigated with pyrene as a polarity-sensitive probe. Multilayer films of poly(styrene sulfonate) (PSS) and various polycations were prepared by the layer-by-layer self-assembly technique. Pyrene (PY) molecules were inserted into the films by exposing the mult…
In situ time-resolved x-ray scattering measurements of hydrogen desorption in ${\mathrm{MgH}}_{2}\ensuremath{-}\mathrm{Nb}$ nanocomposites using synchrotron radiation are presented. Results show that niobium acts like a catalyst for hydrogen absorption and desorption. It is found that hydrogen desorption involves the…
A new method for fabricating macroporous inorganic and inorganic composite materials with tailored pore morphologies (i.e., pore wall thickness and open or closed pore structure) is described. Polystyrene (PS) colloidal spheres coated with polyelectrolyte (PE) multilayers (PS−PE) or silica nanoparticle (SiO 2 )/PE hyb…
We investigate the adsorption processes of a series of positively and negatively charged proteins onto the surface of polyelectrolyte multilayers. We find that proteins strongly interact with the polyelectrolyte film whatever the sign of the charge of both the multilayer and the protein. When the charges of the multil…
Raman and polarized infrared spectra of the mixed stack charge transfer crystal 2-chloro-5methyl-p-phenylendiamine- -2,5-dimethyl-dicyanoquinonediimine (ClMePD-DMeDCNQI) are reported as a function of temperature. A detailed spectral interpretation allows us to gain new insight into the temperature induced neutral-ioni…
We develop the theory for stick-slip motion in ultra-thin liquid films confined between two moving atomically-flat surfaces. Our model is based on hydrodynamic equation for the flow coupled to the dynamic order parameter field describing the ``shear melting and freezing'' of the confined fluid. This model successfully…
We performed dielectric spectroscopy on polypyrrole near the metal-insulator transition (MIT) down to 2 K. We evaluate the dependence of the plasma frequency and the scattering time (t) on the distance to the MIT, characterized by the Fermi-level relative to the band-edge of extended states, E_F-E_c. Especially the st…
A method is reported for obtaining silver colloids with a large particle size. It is based on the growth of seed colloidal particles obtained by chemical reduction of silver nitrate with citrate. These colloids were characterized by means of UV−visible spectroscopy and transmission electron microscopy. The nucleation…
Phosphor particles (ca. 60 nm in size) of yttrium oxide co-doped with Er 3+ and Yb 3+ ions were prepared by a precipitation method in the presence of EDTA. Their physical properties were compared to much larger particles (ca. 600−800 nm in size) prepared in the absence of EDTA. All of the particles were shown to have…
Nb-containing polyoxometalates (POMs) of the Wells-Dawson class inhibit HIV-1 protease (HIV-1P) by a new mode based on kinetics, binding, and molecular modeling studies. Reaction of alpha(1)-K(9)Li[P(2)W(17)O(61)] or alpha(2)-K(10)[P(2)W(17)O(61)] with aqueous H(2)O(2) solutions of K(7)H[Nb(6)O(19)] followed by treatm…
We report the characterization of defects in individual metallic single-walled carbon nanotubes by transport measurements and scanned gate microscopy. A sizable fraction of metallic nanotubes grown by chemical vapor deposition exhibits strongly gate voltage-dependent resistance at room temperature. Scanned gate measur…
We have used ellipsometry to study the thermal expansivity of thin polystyrene films on silicon substrates with thicknesses of 10-200 nm. We find well-defined glass transitions, and detailed analysis of the expansivities shows that for thinner films the transition width is broadened, while the strength of the transiti…
Molecular metals normally require charge transfer between two different chemical species. We prepared crystals of [Ni(tmdt)2] (tmdt, trimethylenetetrathiafulvalenedithiolate) and carried out crystal structure analyses and resistivity measurements. The analyses and measurements revealed that these single-component mole…
Mg(OH) 2 nanocrystallines with rod-, tube-, needle-, or lamella-like morphologies have been synthesized by a hydrothermal reaction using different magnesium precursors and solvents as the reactants. The products appeared to have narrow size distributions with a monodisperse nature. Subsequent thermal decomposition at…
A purification method has been developed that provides for the removal of metal catalysts and impurity carbon from laser-oven-grown single-wall carbon nanotube (SWNT) material. The oxidation rate of SWNTs in air at elevated temperatures is correlated to the metal content of the sample. Sample purity is documented with…
Inelastic neutron-scattering study of a deuterated crystal of Rochelle salt confirms the existence of a resonant mode near 25 ${\mathrm{cm}}^{\ensuremath{-}1}$ at 50 K which softens with increasing temperature and becomes overdamped on approaching the phase transition to the ferroelectric phase. We argue that this mod…
We present the first muon spin rotation/relaxation study of a nematic liquid crystal (5CB). We identify four different positions for muonium addition to this compound by correlating the dominant peaks in the Fourier transform of the muon precession signal obtained in an applied transverse magnetic field. Experiments p…