Materials Literature
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The surface chemistry of coke precursors on spent fluid catalytic cracking catalysts during the oxidative regeneration process was investigated by temperature-programmed desorption and temperature-programmed oxidation experiments and IR spectroscopy. NH 3 and HCN are formed via cracking and hydrolysis reaction of coke…
Aluminum was incorporated into the mesoporous framework of ethane−silica by one-pot condensation of Al(O i Pr) 3 with 1,2-bis(trimethoxysilyl)ethane using octadecyltrimethylammonium chloride as surfactant. Powder X-ray diffraction patterns, nitrogen sorption analysis, and TEM results reveal the formation of an ordered…
In this article we report on the conductance of bundles of single-wall carbon nanotubes as a function of temperature and bias voltage. We focus on the nonlinearity in the IV curves near zero bias, i.e., a pronounced conductance dip. While we observe that all temperature dependent data scale onto a single curve, we als…
A novel method for the purification of single-walled and multiwalled carbon nanotubes is described. The method involves acid washing followed by hydrogen treatment in the 700−1000 °C range. While acid washing dissolves the metal particles, the hydrogen treatment removes amorphous carbon as well as the carbon coating o…
Abstract Contact angles and surface tension data were measured to obtain the surface tension components of polyacrylamide (PAM). According to Van Oss, Chaudhury, and Good (VCG) theory, the surface tension components were used to calculate the PAM solubility in five different polar solvents: water, ethylene glycol (EG)…
A new class of discotic liquid crystals derived from tris(N-salicylideneanilines) existing exclusively in their C3h and Cs keto-enamine tautomeric forms is reported. These compounds self-assemble to form columnar liquid crystalline phases with a small core-core separation as evidenced by X-ray diffraction studies.
Abstract A method has been developed for the quantitative determination of the composition of thermoplastic wood composites. The method involves area measurements of the two peaks in the derivative curve of a tracing produced by the thermogravimetric analysis (TGA) of a thermoplastic composites sample in an inert atmo…
Abstract Toughening of recycled poly(ethylene terephthalate) (PET) was carried out by blending with a maleic anhydride grafted styrene‐ethylene/butylene‐styrene triblock copolymer (SEBS‐ g ‐MA). With 30 wt % of the SEBS‐ g ‐MA, the notched Izod impact strength of the recycled PET was improved by more than 10‐fold. SEM…
Visible quantum cutting (visible two-photon luminescence) through downconversion is observed for the Gd3+–Eu3+ couple in Eu3+-doped KGd3F10 (KG3F) and KGd2F7 (KG2F). The dependence of the efficiency of cross-relaxation required for visible quantum cutting on the Eu3+-doping concentration and crystal structure is discu…
Synthesis and characterization of organic spin clusters, high-spin poly(arylmethyl) polyradicals with 24 and 8 triarylmethyls, are described. Polyether precursors to the polyradicals are prepared via modular, multistep syntheses, culminating in Negishi cross-couplings between four monofunctional branch (dendritic) mod…
First through fourth generation (G1-G4) dendronized macromonomers, 3, 5, 7, and 9, with a methyleneoxycarbonyl spacer between the polymerizable group and dendritic side chain (dendron) were synthesized, and their polymerization behavior to the corresponding dendronized polymers PG1s, PG2s, PG3s, and PG4s, respectively…
It has been observed that a ring-type magnetoelectric laminate composite of circumferentially magnetized magnetostrictive Tb1−xDyxFe2 and circumferentially polarized piezoelectric Pb(Zr,Ti)O3 layers has a large magnetoelectric voltage gain effect, offering potential in high-power miniature transformer applications.
We quantify experimentally the efficiency of excitation transfer from a semiconducting polymer matrix to quantum dot nanocrystals. We study 5±0.5 nm PbS nanocrystals embedded in MEH-PPV (poly[2-methoxy-5-(2′-ethylhexyloxy-p-phenylenevinylene)]) polymer. We determine the excitation transfer efficiency from normalized p…
Hard x-ray valence band photoemission spectroscopy (PES) is realized using high-energy and high-brilliance synchrotron radiation. High-energy (∼6 keV) excitation results in larger probing depths of photoelectrons compared to conventional PES, and enables a study of intrinsic electronic property of materials in actual…
We report a measurement of the parity-violating asymmetry in fixed target electron-electron (M\o{}ller) scattering: ${A}_{\mathrm{PV}}=[\ensuremath{-}175\ifmmode\pm\else\textpm\fi{}30(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}20(\mathrm{syst})]\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}$. This first direc…
Periodic density functional theory (DFT) based on plane waves (PW) and Hartree−Fock (HF) based on the linear combination of atomic orbitals (LCAO) calculations using slabs separated by vacuum gaps were carried out to model the H 2 O−TiO 2 (rutile) (110) interface. Positions of all atoms were allowed to relax except at…
Tensile stress–strain curves demonstrate that single-phase nanocrystalline face-centered-cubic (fcc) metals are intrinsically ductile and their failure begins with necking. However, the area reductions and the fracture behaviors were found to be dependent on the grain size. When plastic deformation is governed by disl…
Ionically dispersed Rh over CeO 2 in Rh/CeO 2 catalysts prepared by a single step solution combustion method is shown to improve the redox property and catalytic activity. The H 2 /Rh ratio obtained from hydrogen uptake measurement was 5.4, 2.4, and 2.1, respectively in 0.5, 1, and 2% Rh/CeO 2, indicating a significan…
The addition of Pd into Ni/SiO 2 improved the catalytic activity and life for methane decomposition into hydrogen and carbon nanofibers. Thus, Pd-added Ni/SiO 2 (denoted as Pd−Ni/SiO 2 ) was characterized by measuring the Ni and Pd K-edge XANES and EXAFS and TEM images. Methane decomposition on Ni/SiO 2 or Pd/SiO 2 fo…
The structure of homogeneous binary SiO 2 −Al 2 O 3 glasses with 0.4 to up to 12.0 wt % Al 2 O 3 have been studied using high-resolution 27 Al, 17 O, and 29 Si NMR spectroscopic techniques. All glasses are found to contain a mixture of 4-, 5-, and 6-fold coordinated Al sites (Al IV, Al V, and Al VI ). The relative pro…