The Synthesis of Symmetrical Phthalocyanines
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Enhanced Raman microprobe imaging of single-wall carbon nanotubes
We explore Raman microprobe capabilities of visualizing single-wall carbon nanotubes (SWCNTs). Although this technique is limited to the micron scale, we demonstrate that images of individual SWCNTs, bundles, or their agglomerates can be generated by mapping Raman active elementary excitations. We measured the Raman r…
Self-Assembled Nanocoils
Ceramics are generally thought to be much more brittle than metals or polymers. At the nanoscale, however, ceramic materials can exhibit surprising flexibility. In his Perspective, Korgel discusses work reported in the same issue by Kong et al. on the synthesis of nanocoils of zinc oxide. Nanoribbons created by vapor…
Interfacial phase formation in Cu–Mg alloy films on SiO2
We report the chemical changes and phase formation at the film-SiO2 interface during vacuum annealing of supersaturated Cu–10 at. % Mg alloy films sputter-deposited on SiO2. High-resolution transmission electron microscopy, energy dispersive x-ray spectroscopy and electron energy loss spectroscopy reveal that both Cu…
Photoluminescence and photosensitive properties of ZnO strands self-twined by nanowires
Using argon as the transporting gas, freestanding macroscopic ZnO strands have been synthesized by evaporating metal zinc pellets at 900 °C in a quartz tube. Scanning electron microscopy images show that the macroscopic ZnO strands are self-twined by ZnO nanowires with a diameter in the range of 20–30 nm. A ZnO strand…
Interaction of colloids with a nematic-isotropic interface
The Landau-de Gennes free energy is used to calculate the interaction between long cylindrical colloids and the nematic-isotropic (NI) interface. This interaction has two contributions: one is specific of liquid crystals and results from the deformation of the director field close to the particles or to the interface,…
Electron field emission from room temperature grown carbon nanofibers
The observation of field induced electron emission from room temperature grown carbon nanofibers at low (5 V/μm) macroscopic electric fields is reported. The nanofibers were deposited using methane as a source gas in a conventional rf plasma enhanced chemical vapor deposition reactor using a Ni metal catalyst previous…
Structure of Two Azide Salts of a Copper(II) Macrocycle and Magnetic Properties of Cu(14ane)Cu(N3)4
Synthesis of azide complexes with the copper(II) macrocycle complex Cu(14ane)(2+) (where 14ane = 1,4,8,11-tetraazacyclothetradecane) has yielded two compounds. Cu(14ane)Cu(N(3))(4) contains micro(1,3)-azido bridged chains of Cu(14ane)(2+) cations and Cu(N(3))(4)(2)(-) anions. Magnetic studies reveal the presence of fe…
Ultrafast collective dynamics in the charge-density-wave conductor K0.3MoO3
Low-energy coherent charge-density wave excitations are investigated in blue bronze (K(0.3)MoO(3)) and red bronze (K(0.33)MoO(3)) by femtosecond pump-probe spectroscopy. A linear gapless, acousticlike dispersion relation is observed for the transverse phasons with a pronounced anisotropy in K(0.33)MoO(3). The amplitud…
Dynamically cured polypropylene/epoxy blends
Abstract The dynamic vulcanization process, usually used for the preparation of thermoplastic elastomers, was used to prepare polypropylene (PP)/epoxy blends. The blends had crosslinked epoxy resin particles finely dispersed in the PP matrix, and they were called dynamically cured PP/epoxy blends. Maleic anhydride gra…
Epitaxial PbTiO3 thin films grown on (100) MgO by pulsed-laser deposition for optical waveguiding properties
Perovskite single phased PbTiO3 thin films have been grown by pulsed-laser deposition on (100) MgO single crystals in order to prepare high quality optical waveguides. The substrate temperature and the oxygen pressure during the deposition have been optimized to improve crystalline quality and to grow epitaxial thin f…
Novel Coassembly Route to Cu−SiO2 MCM-41-like Mesoporous Materials
A series of mesostructured Cu-SiO2 composites have been synthesized with sodium metasilicate (Na2SiO3) and cuprammonia nitrate (Cu(NH3)4(NO3)2) respectively used as Si and Cu sources. The synthetic procedures were conducted at room temperature, and cetyltrimethylammonia bromide was used as a template. Under our experi…
Theory of the acoustic realignment of nematic liquid crystals
When an ultrasonic wave is applied to a nematic liquid-crystal cell, the molecules change their orientation, leading to a change in the optical intensity transmitted through the cell. Modeling this acousto-optic effect involves three separate theoretical issues: (a) calculating the intensity of sound transmitted throu…
Interpretation of x-ray and neutron diffraction patterns for liquid and amorphous yttrium and lanthanum aluminum oxides from computer simulation
Simulation models, based on an ionic description of closed-shell species and which incorporate many-body polarization effects, are derived for both yttrium and lanthanum aluminates using physically transparent mixing and scaling arguments. Three compositions $(20%{\mathrm{Y}}_{2}{\mathrm{O}}_{3}/80%{\mathrm{Al}}_{2}{\…
Crystallization of Eflucimibe Drug in a Solvent Mixture: Effects of Process Conditions on Polymorphism
Nucleation and metastability of the eflucimibe ( S )-2‘,3‘,5‘-trimethyl-4‘-hydroxy-dodecylthiophenyl-acetanilide, a new acyl-coenzyme A:cholesterol O -acyltransferase (ACAT) inhibitor, have been investigated according to a polythermal method. Eflucimibe exhibits two polymorphs, A and B, which crystallize simultaneousl…
Functionalization of carbon nanotubes using phenosafranin
Spectroscopic analysis and atomic force microscopy (AFM) phase imaging studies show self-assembly of phenosafranin (PSF) to multiwalled carbon nanotubes (MWNTs). The shift in absorption spectra is associated with charge transfer of valence electrons from PSF to electron accepting sites on the MWNTs. The Raman-active d…
Ferrocenylethynylbenzenes as Precursors to in Situ Synthesis of Carbon Nanotube and Fe Nanoparticle Compositions
Several ferrocenyl-aryl-acetylenic compounds were synthesized and thermally converted in situ to carbon nanotube−Fe nanoparticle compositions. Upon melting, the ferrocenyl compounds are cured to a shaped configuration through the acetylenic units. Further heating of the polymeric composition results in the decompositi…
Vibrational signature of broken chemical order in aGeS2glass: A molecular dynamics simulation
Using density-functional molecular dynamics simulations, we analyze the broken chemical order in a ${\mathrm{GeS}}_{2}$ glass and its impact on the dynamical properties of the glass through the in-depth study of the vibrational eigenvectors. We find homopolar bonds and the frequencies of the corresponding modes are in…
Oxamidate-Bridged Dinuclear Five-Coordinate Nickel(II) Complexes: A Magneto−Structural Study
The preparation, spectroscopic characterization, and magnetic study of three new oxamidate-bridged nickel(II) dinuclear complexes of formulas ([Ni(Me3[12]aneN3)]2(mu-oa))(PF6)2 (1), ([Ni(Me3[12]aneN3)]2(mu-dmoa))(PF6)2 (2), and ([Ni(Me3[12]aneN3)]2(mu-dpoa))(PF6)2 (3) (Me3[12]aneN3 = 2,4,4-trimethyl-1,5,9-triazacyclod…
Infrared-laser induced photon avalanche upconversion in Ho3+–Yb3+ codoped fluoroindate glasses
An intense green upconversion emission due to a photon avalanche mechanism has been observed in Ho3+–Yb3+ codoped fluroindate glasses, measured at 200 K, under excitation at around 750 nm. The influence of the Yb3+ concentration on the photon avalanche process has been studied. The pump power threshold of the avalanch…