Materials Literature
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The effects of the inclusion of manganese in small ZnS nanocrystals are investigated. Our calculation is based on a tight-binding model with renormalized parameters similar to those of the defect-molecule approach for substitutional transition-metal ions in semiconductors. The nanocrystals of Mn-doped ZnS were 1.1--3.…
Peroxide induced crosslinking and degradation of polyvinyl chloride (PVC) were experimentally investigated using an on-line electron spin resonance (ESR) spectroscopy technique. The reaction variables included temperature, peroxide type and concentration. A single line ESR spectrum was observed with its peak-to-peak w…
Transport data for paratoluene sulfonate dope polypyrrole films in the insulating regime and near the metal-insulator (M-I) boundary are presented and analyzed. Samples in the insulating region show a crossover from Mott to Efros–Shklovskii variable range hopping conduction at T=5 K and magnetoconductance of these sam…
Degradation of poly(methyl methacrylate) (PMMA) thin films by vacuum ultraviolet (VUV) monochromatic synchrotron radiation was investigated by ultraviolet photoelectron spectroscopy. The photodegradation reaction was analyzed, for the first time, by different spectrometry techniques and ab initio molecular orbital cal…
A beam of light incident upon a diffractive structure can under resonance conditions be subject to a rather large lateral displacement. The effect is demonstrated with a Gaussian profile beam and two geometries based on a waveguide grating and a single-mode waveguide.
The doping of the chemical vapor deposition (CVD)-diamond $(100):\mathrm{H}(2\ifmmode\times\else\texttimes\fi{}1)$ surface with B and N has been studied using the density-functional tight-binding method. In agreement with recent experimental results, B doping is found to lower the abstraction energies and remove diffu…
We present a microscopic model to understand the magnetoelectric and second-harmonic spectra of ${\mathrm{Cr}}_{2}{\mathrm{O}}_{3}$ and the interference effect between the magnetic $({\ensuremath{\chi}}^{m})$ and electric $({\ensuremath{\chi}}^{e})$ second-order optical polarizations. The spin-orbit interaction and th…
We study the depletion interaction between spherical particles of radius R immersed in a dilute solution of rigid rods of length L . The computed interaction potential is, within numerical accuracy, exact for any value of L / R . In particular we find that for L ∼ R , the depth of the depletion well is smaller than th…
Highly branched poly(ε-caprolactones) with novel and well-defined molecular architectures have been synthesized by the use of new multifunctional initiators. The ring-opening polymerization methods used to prepare these new structures allowed accurate control of molecular weight and narrow molecular weight distributio…
Transparent oxyfluoride glass-ceramics can provide a low- phonon energy fluoride environment for active rare earth ions while maintaining the durability, formability, and mechanical strength of an oxide glass. Fluorescence from RE doped samples indicate substantial partitioning into the fluoride crystals. Eu<SUP>3+</S…
We have established time–temperature transformation and continuous-heating transformation diagrams for poly(ether–ether–ketone) (PEEK) and PEEK/poly(ether–imide) (PEI) blends, in order to analyze the effects of relaxation control on crystallization. Similar diagrams are widely used in the field of thermosetting resins…
The effects of electron-electron interaction on properties of zigzag carbon nanotubes with caps at both ends are theoretically investigated by employing an extended Peierls-Hubbard model. The electron-electron interaction is treated within the frame of Hartree-Fock approximation. Then the electronic structures and opt…
The process of order-to-disorder transition (ODT) has been studied in a symmetric diblock copolymer AB and in an asymmetric miktoarm star block copolymer of the AB3 type. We find that the TODT depends on the ordering temperature just as the melting temperature in semicrystalline homopolymers depends on the crystalliza…
The melting behavior of poly(ethylene terephthalate co-1,4-cyclohexylene dimethylene terephthalate) [PET/CT] random copolyesters has been studied. The basis of this analysis was the triple melting behavior of PET homopolymers, which is commonly observed after a period of isothermal crystallization followed by linear h…
A first-principles study of the frequency-dependent second-harmonic generation (SHG) coefficients of various SiC polytypes $(2H$, $4H$, $15R$, $6H$, and $3C)$, a group spanning the complete range of ``hexagonality,'' was carried out. It uses a recently developed computational approach based on the self-consistent line…
The gene fgd, which codes for F420-dependent glucose-6-phosphate dehydrogenase (FGD), was cloned from Mycobacterium smegmatis, and its sequence was determined and analyzed. A homolog of FGD which has a very high similarity to the M. smegmatis FGD-derived amino acid sequence was identified in Mycobacterium tuberculosis…
ABA-type block copolymers of poly(trimethylene carbonate) with poly(ethylene glycol) (Mn 6820), PTMC-b-PEG-b-PTMC, were synthesized by the ring-opening polymerization of 1,3-dioxan-2-one (trimethylene carbonate) in the presence of poly-(ethylene glycol) with stannous octoate catalyst, and the copolymers with various c…
Two chalcone-derivative isomers, 4,4′-diaminochalcone (4DAC) and 3,3′-diaminochalcone (3DAC), were synthesized and used as monomers together with tetracarboxylic dianhydrides to prepare novel photosensitive polyimides that contain a chalcone moiety in the main chain. The polyimides were characterized and their photoch…
SrRuO 3 epitaxial thin films were prepared by pulsed laser deposition (PLD) under a range of growth conditions to study the impact of bombardment on properties. Growth conditions favoring energetic bombardment resulted in SrRuO3 films with expanded in-plane and out-of-plane lattice constants. In particular, SrRuO3 fil…
The gene encoding the Escherichia coli Class I fructose-1, 6-bisphosphate aldolase (FBP aldolase) has been cloned and the protein overproduced in high amounts. This gene sequence has previously been identified as encoding an E. coli dehydrin in the GenBanktrade mark database [gene dhnA; entry code U73760; Close and Ch…