Materials Literature
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A new Landau free energy is derived for diblock copolymers of incompatible pairs based on the recently developed compressible random-phase approximation analysis. Finite compressibility of each block is generally allowed. The inhomogeneity of each block density and free volume is analyzed in the weak segregation regim…
A combination of NMR and MALDI was found to be a suitable tool to study the exchange reactions that occur during the melt mixing of Nylon-6 and poly(butylene terephthalate) (Ny6/PBT) blends. The results reveal the essential role of carboxyl end groups in the exchange reaction, and allow drawing a detailed mechanism fo…
We consider the micellization of block copolymers in solution, employing self-consistent field theory with an additional constraint that permits the examination of intermediate structures. From the information for an isolated micelle (structure, binding energy, free energy) we describe how the global thermodynamics of…
The Bacillus subtilis proteins involved in the utilization of L-arabinose are encoded by the araABDLMNPQ-abfA metabolic operon and by the araE/araR divergent unit. Transcription from the ara operon, araE transport gene and araR regulatory gene is induced by L-arabinose and negatively controlled by AraR. Additionally,…
Ring-opening polymerization of ε-caprolactone has been initiated by Y isopropoxide grafted onto silica, in the presence of 2-propanol, in toluene at 40 °C. The degree of polymerization is controlled by the initial monomer/(alcohol + alkoxide) molar ratio. Deactivation of the chains by an alcohol is essential for them…
Atomic force microscopy was adopted to study the nanoscopic structure formation of natural fibrous protein, fibroin from the Samia cynthia ricini wild silkworm. We have observed highly ordered nanoscale textile-fabric-like structures of fibroin molecules. From AFM and SDS-PAGE experiments, it was revealed that fibroin…
Supercooled liquids in the Y 2 O 3 –Al 2 O 3 system undergo a liquid–liquid phase transition between a high-temperature, high-density amorphous polymorph (HDA form), and one with lower density that is stable at lower temperature (LDA form). The two amorphous polymorphs have the same chemical composition, but they diff…
The configurational entropy Sc, which is a basic quantity in theoretical descriptions of the glass transition, is evaluated for a multicomponent polymer system using the lattice cluster theory. This theoretical treatment of Sc represents an extension of the Gibbs–DiMarzio theory to a mixture of semiflexible, interacti…
The binding and reversibility of Thermobifida fusca intact Cel5A, Cel5B, and Cel48A and their corresponding catalytic domains (CDs) to bacterial microcrystalline cellulose (BMCC) were studied at 5 degrees C. The binding of the intact cellulases and of corresponding CDs to BMCC was irreversible in all regions: Langmuir…
9R9. Mechanics of Solids and Shells: Theories and Approximations. - G Wempner (Georgia Inst of Tech, Atlanta GA) and D Talaslidis (Aristotle Univ, Thessaloniki, Greece). CRC Press LLC, Boca Raton FL. 2003. 529 pp. ISBN 0-8493-9654-9. $119.95.Reviewed by J Petrolito (Sch of Sci and Eng, La Trobe Univ, PO Box 199, Bendi…
The use of two orthogonal, external fields is shown to control the orientation of lamellar microdomains in three dimensions in diblock copolymer thin films. An elongational flow field was applied to obtain an in-plane orientation of the microdomains of the copolymer melt, and an electric field, applied normal to the s…
FliJ, a 17-kDa protein, is a soluble component of the Salmonella type III flagellar protein export system that has antiaggregation properties and several other characteristics that suggest it may have a chaperone-like function. We have now examined this protein in detail. Ten-amino-acid scanning deletions covering the…
We report the growth by molecular beam epitaxy and the optical characterization of GaN films nucleated on a Si(111) surface that has been patterned by dry etching an ordered array of nanometer-scale pores prior to the growth. The etching is performed using an anodized aluminum oxide membrane as a mask. The nanopore ar…
Brillouin scattering measurements on the nanocrystalline cubic phase of ${\mathrm{BC}}_{2}\mathrm{N},$ the hardest known solid after diamond, have been successfully performed using the ``emulated'' platelet scattering geometry. We were able to measure both longitudinal ${(V}_{p})$ and shear ${(V}_{s})$ velocities inde…
We report the electrical properties of a single conducting polyaniline nanotube measured by a standard four-terminal technique. Camphor sulfonic acid doped polyaniline nanotubes were self-assembled by a template-free method. The directly measured conductivity of the single polyaniline nanotube is very high (∼31.4 S/cm…
Molecular dynamics simulations are performed to investigate the behaviour of helium atoms generated from tritium decay in perfect Cu crystals at 300 K. At the early stage just after a 3 He atom generation, the lattice structure is badly deformed and the local temperature rises considerably above 300 K. Single 3 He ato…
Direct heteroepitaxial growth of uniform stoichiometric CuInS2 (CIS) thin films on sapphire (0001) substrates has been achieved by radio frequency reactive sputtering. X-ray ω–2θ scans reveal that the sputtered layers grow in a (112) orientation with a chalcopyrite structure. A rocking curve full width at half maximum…
Structures of (FeO) x (P 2 O 5 ) 1− x glasses with 0.2 ≤ x ≤ 0.5 are studied by x-ray diffraction using high energy photons from a synchrotron. Scattering intensities are obtained up to Q max of 250 nm −1 . P–O, Fe–O and O–O first-neighbour peaks are well resolved in the pair distribution functions. Constant P–O coord…
Adapting metabolic enzymes of microorganisms to low temperature environments may require a difficult compromise between velocity and affinity. We have investigated catalytic efficiency in a key metabolic enzyme (dihydrofolate reductase) of Moritella profunda sp. nov., a strictly psychrophilic bacterium with a maximal…
Simple p–n junctions have been fabricated using a simple heteroepitaxial structure of La0.67Ca0.33MnO3−δ/Nb-doped SrTiO3. In such junctions, the La0.67Ca0.33MnO3−δ exhibits semiconductor behavior due to oxygen deficiency, whereas the Nb–0.7 wt %-doped SrTiO3 shows a metal behavior. These junctions demonstrate good rec…