Materials Literature
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Changes in the structural properties of sodium alumino-silicate glasses of general formula Na 2 O· x Al 2 O 3 ·(3− x )SiO 2 were investigated as a function of Al 2 O 3 concentration. The experimental evidences provided by density, elastic modulus, glass chemical resistance measures, 29 Si and 27 Al MAS NMR investigati…
The following tungsten fluorides have been synthesized by simple addition reactions or by reduction with tungsten metal at elevated temperature: KWF7, K2WF8, MWF6 (M = K, Na, Rb, Cs), K2WF7, M3WF8 (M = K, Na, Rb), and K3WF6. The compounds were characterized by their Raman spectra and by cyclic voltammetry in the molte…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTPreparing High-Density Polymer Brushes by Mechanically Assisted Polymer AssemblyTao Wu, Kirill Efimenko, and Jan GenzerView Author Information Department of Chemical Engineering, North Carolina State University, Raleigh, North Carol…
The magnetic and magnetotransport properties of field-aligned half-metallic ${\mathrm{CrO}}_{2}$ powders have been studied. Needle-shaped nanoparticles of ${\mathrm{CrO}}_{2}$ have been aligned in a strong magnetic field. The aligned powder sample shows a strong anisotropy along the alignment direction. The conduction…
We found the effect of a hidden photoalignment of a dye-doped nematic liquid crystal (LC) on a nonphotosensitive polymer surface after polarized irradiation of the cell in the isotropic phase. We observed that irradiation resulted in a uniform planar orientation of the LC after cooling to the mesophase. The direction…
The influence of homoatomic d 10 ···d 10 interactions in the structural and physical properties of some copper-containing oxides has been investigated by using semiempirical band structure calculations of the extended Hückel type. Comparison of the band structures of CuAlO 2 and Cu 2 O, two compounds with Cu(I) ions i…
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…