Materials Literature
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There are three members of the HtrA family of serine proteases, YkdA, YvtA, and YyxA, encoded in the chromosome of Bacillus subtilis. In this study, we report on the promoter structure and regulation of ykdA expression. The ykdA gene is heat inducible, exhibiting a biphasic pattern of expression during a 60-min interv…
A computer simulation method is devised whereby the change in location of a triple point is followed as one of the parameters of the interaction potential is modified. The method, a two-dimensional Clapeyron integration, is illustrated here for the case of a hard-core plus repulsive Yukawa potential of variable range.…
Electrical conductivity effects in biaxially stretched polyethylene terephthalate (PET) films of 6 μm thickness and 68% degree of crystallinity were investigated by means of dielectric relaxation spectroscopy in the frequency range 10−2–106 Hz and at temperatures higher than the glass transition temperature (∼85 °C) u…
A set of new aromatic polyamides were synthesized by the direct phosphorylation condensation of 4-(1-adamantyl)-1,3-bis-(4-aminophenoxy)benzene with various diacids. The polymers were produced with high yields and moderate to high inherent viscosities (0.43–1.03 dL/g), and the weight-average molecular weights and numb…
An analysis of the second-order resonant Raman spectra of single-walled carbon nanotubes using different laser energies in the range 1.58--2.71 eV is presented. Major emphasis is given to the overtones and combination modes associated with the two dominant features of the first-order spectra, the radial breathing mode…
Optical properties of Nd 3+ -doped phosphate glasses have been studied on the basis of the Judd-Ofelt theory. With the intermediate cross-section value and the weak 4 / 6 parameter, we expect a relatively prominent 4 F 3/2 4 I 11/2 laser emission. The quenching effect of the emission intensity is discussed in terms of…
We have synthesized samples in the system CaTi 1 - x Fe x O 3 - x /2 with x = 0.05 - 0.38 at temperatures of 900 - 1320 °C under controlled conditions of oxygen fugacity. After drop quenching, samples were characterized by x-ray diffraction, transmission electron microscopy (TEM) and Mössbauer spectroscopy. Electrical…
Most stable structures and physical properties are studied for silicon-doped ${\mathrm{Al}}_{13},$ ${\mathrm{Al}}_{19},$ and ${\mathrm{Al}}_{23}$ clusters using the ab initio molecular-dynamics method within the framework of a plane-wave pseudopotential approach and the local density as well as the generalized gradien…
The surface loss probabilities of hydrocarbon radicals on the surface of amorphous hydrogenated carbon (C:H) films are investigated by depositing films inside a cavity with walls made from silicon substrates. This cavity is exposed to a discharge using different hydrocarbon source gases. Particles from the plasma can…
We have investigated, in single crystals of ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Ca}}_{x}{\mathrm{MnO}}_{3},$ the insulator-metal (IM) transition at the ground state induced by carrier doping or applying pressure around the critical doping level ${(x}_{c}\ensuremath{\approx}0.22).$ The up turn of the resistivity…
Transient photoconductivity in thin-film ${\mathrm{Nb}}_{x}{\mathrm{Ti}}_{1\ensuremath{-}x}{\mathrm{O}}_{2}$ and ${\mathrm{TiO}}_{2}$ was studied as a function of temperature, light intensity, illumination time, and ambient composition in a time range of ${10}^{\ensuremath{-}2}--{10}^{7}\mathrm{s}.$ Both excitation an…
Ultrasonic microspectroscopy technology, using the line-focus-beam and plane-wave ultrasonic material characterization system, is applied to characterization of silica glass. Eight types of commercial silica glasses fabricated by different production methods and conditions are used as specimens to measure their acoust…
Luminescence and excitation spectra of ${\mathcal{R}}^{3+}$-doped thorium oxide $({\mathcal{R}}^{3+}={\mathrm{Eu}}^{3+}{,\mathrm{}\mathrm{Dy}}^{3+})$ are reported and analyzed. ${\mathrm{ThO}}_{2}$ was synthesized and grown as crystal using the flux technique. Usually, ${\mathcal{R}}^{3+}$ ions substitute ${\mathrm{Th…
A “coupling to” approach was developed for the synthesis of hybrid dendritic–linear block copolymers. Fréchet-type polyether dendrons were prepared by the convergent growth approach and coupled with well-defined functionalized polystyrene backbones prepared by living free radical procedures. The subtle interplay betwe…
The chronic inflammatory response associated with the abluminal surface of polymeric vascular grafts has been suggested to affect adversely graft neovascularization, the cellular response at the luminal surface of vascular grafts, and overall graft patency. To better understand the source for this chronic inflammation…
Photoemission and x-ray absorption spectroscopy have been used to study silicon nanowires prepared by a laser ablation technique together with Si(100) and porous silicon. Si $2p$ and valence-band spectra show that the Si nanowires are essentially crystalline Si encapsulated by silicon oxide. HF etching removes the sur…
A thermally stimulated luminescence (TSL) study in the temperature range 20--300 \ifmmode^\circ\else\textdegree\fi{}C has been performed after x-ray irradiation on mixed ${\mathrm{Lu}}_{x}{\mathrm{Y}}_{1\ensuremath{-}x}{\mathrm{AlO}}_{3}:\mathrm{C}\mathrm{e}$ crystals $(x=0.1--0.3)$ and on ${\mathrm{YAlO}}_{3}:\mathrm…
Activated carbon fibers (ACFs) are microporous carbons consisting of a three-dimensional disordered network of nano-graphites with a mean in-plane size of about 30 Å. We investigated the structure, electronic properties and iodine doping effects for ACF samples heat-treated up to 2800° C. The samples heat-treated belo…
The competitive ablation and polymerization (CAP) principle relates the ablation of materials in plasma to the deposition of materials in plasma. Plasma polymerization and plasma treatment cannot be elucidated without consideration of the fragmentation of molecules in both the gas and solid phases. The general fragmen…
By a judicious choice of implantation and annealing conditions, an n-type conducting layer with activation energy of about 0.32 eV has been created in oxygen-implanted diamond. This conclusion was reached as a result of performing three similar implantations in identical, high-purity (type IIa) diamonds. They have bee…