Materials Literature
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The syntheses and mesomorphism of novel octaalkoxymethyl-substituted tetra-2,3-thiophenophorphyrazines, heterocyclic phthalocyanine analogues in which the benzene rings are replaced by thiophene rings, are reported. NMR analysis indicates that these materials exist as isomeric mixtures due to the asymmetry induced by…
Polycrystalline thin films of n-CdSe0.6Te0.4 were deposited in a vacuum of 5×10−5 Torr by thermal flash evaporation with a deposition rate of 20±1 Å/s on indium oxide coated glass plates [σ=1.25×104 (Ω cm)−1] held at 200 °C. Application of surface treatment techniques such as annealing and photoelectrochemical etching…
In a systematic investigation of the effect of dopant composition on dosimetric characteristics of thermoluminescent LiF:Mg,Cu,P phosphor, 130 samples were prepared with different concentrations of all activators over the following ranges: Mg (0-1.0 mol%), Cu (0-0.5 mol%) and P (0-5.0 mol%). From each material a group…
The effect of proline on the prevention of trichloroacetic acid (TCA)-induced protein precipitation is studied. It is found that proline at high concentrations (> 4.0 M) completely prevents TCA-induced precipitation of hen egg white lysozyme. Other osmolytes such as ethylene glycol, glycerol and sucrose fail to preven…
Ni and mixed Ni‐Co oxide films were formed at Pt substrates by the sol‐gel technique and studied electrochemically in 1 M NaOH solutions. All sol‐gel films under study have to be found amorphous. The charge densities of these films are quite high compared to oxides formed by the anodic oxidation of metallic substrates…
In this paper we describe the peculiar structures and preferential codon usage found in wild silkworm fibroin genes. We determined a 1350 bp nucleotide sequence from the Chinese oak silkworm, Antheraea pernyi. The deduced amino acid sequence was partitioned into thirteen polyalanine-containing repetitive motifs, which…
A variety of phenyl-containing polymer surfaces have been oxidized using low pressure non-equilibrium O 2 glow discharges. Characterization by X-ray photoelectron spectroscopy has shown that the level of oxygen incorporation can be correlated to the intensity of the C(1s) π−π* valence transition measured for the untre…
The energy states of oxygen-deficient type defects in the vacuum ultraviolet region are discussed based on the experimental results of vacuum ultraviolet absorption, temperature dependence of the photoluminescence (PL) intensities at 4.3 and 3.1 eV, and lifetimes of the PLs. It was found that the oxygen-deficient type…
We have measured the fracture toughness, G c, of an interface between polystyrene (PS) and poly (2-vinylpyridine) (PVP) reinforced with triblock copolymers (PVP- b -dPS- b -PVP) as a function of the areal chain density, Σ, of the copolymers at the interface. The failure mechanisms of the interface are studied by trans…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTRational Design of a Hexagonal Columnar Mesophase in Telechelic Alternating Multicomponent Semifluorinated Polyethylene OligomersV. Percec, D. Schlueter, and G. UngarView Author Information The W. M. Keck Laboratories for Organic Synthesis, Department of Macromolecular Science,…
The peroxy radical (ROO) is unique among reactive oxygen species implicated in the production of DNA damage in that it possesses an extremely long half-life (order of seconds) and is predicted to have a relatively greater chemical selectivity in its reactions relative to other radical intermediates. Yet no product stu…
Fluoromethylene cyanate ester resins derived from the monomer series N⋮CO−CH 2 (CF 2 ) n CH 2 −OC⋮N (where n = 3, 4, 6, 8, and 10) have been synthesized and characterized. Monomer melting points range from −8 to 181 °C, and characterization includes 1 H, 13 C, and 19 F NMR and IR spectroscopy and DSC. Purification is…
The new generation of silicon‐carbide‐based fibres made from organosilicon precursors, cross‐linked by electron irradiation, have been compared with the earlier fibres which have undergone cross‐linking in air. The latest fibres, known as Tyranno Lox‐E and Hi‐Nicalon, possess a lower oxygen content (≈5 wt% and ≈0.5 wt…
The peculiar feature of copper ion-exchanged mordenite in dinitrogen (N 2 ) adsorption has been investigated through the measurements of infrared (IR) and emission spectra (ES) and X-ray absorption fine structure (XAFS). IR spectra provided the definitive evidence for the existence of at least two kinds of adsorption…
A combination of two in situ small-angle scattering techniques are employed to compare the texture and molecular order in flowing LCPs that exhibit constant viscosities (region II) and shear thinning (region I) at low shear rates. The microstructure is characterized by an overall molecular orientation S eff, a texture…
We have measured the V 2p3/2 and O 1s X-ray absorption spectra of singlecrystal V2O5 and compared them with linear-combination-of-atomic-orbitals density-of-states (DOS) calculations. The spectra change dramatically with incident angle and the use of polarized light and a single crystal limits the number of transition…
Investigations have been performed on the La‐modified (1 ‐ x )Pb(Mg 1/3 Nb 2/3 )O 3 —( x )PbTiO 3 crystalline solution for compositions close to the morphotropic phase boundary (MPB) using energy‐dispersive X‐ray spectrometry (EDS). Studies were performed on specimens with La contents between 0 and 10 at.% for x = 0.3…
The present status of the dominant mechanisms of charge-carrier scattering in lead telluride is analyzed critically. It is shown that the role of the Coulomb potential of the vacancies and the role of the deformation potential of acoustic phonons in carrier scattering in PbTe has been strongly overestimated in most ex…
The structure of nanocomposites fabricated using carbon nanotube templates using transmission electron microscopy and electron energy‐loss spectroscopy will be described here. Examples for filled, network substituted and uniformly coated nanotubes will be described. The novelty of such nanocomposite structures and the…
Several molecular devices based on the electronic switching properties of conducting polymers have been described previously and involve an addition/removal of a proton/electron to/from the polymer chain. This “doping” process creates charged topological defects such as polarons or bipolarons, which act as charge carr…