Materials Literature
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Abstract The real stucture of a new crystalline high temperature phase, metastable at room temperature, in the system sodium – bismuth – oxygen, β -Na 3 BiO 4 , was determinated using high resolution X-ray powder diffraction, pair distribution function analysis, and high resolution transmission electron microscopy. β…
We prepared polycrystalline samples of β-KxBa1−xCu2S2 (x=0,0.05,0.1) with a natural superlattice structure and measured the thermoelectric properties from room temperature to about 850K. The Seebeck coefficients are positive in the whole temperature range. The electrical resistivity and Seebeck coefficient decrease wi…
Using computer programs, we enumerate and classify the tiling behavior of small polyominoes (n ≤ 9), polyhexes (n ≤ 7), and polyiamonds (n ≤ 10). For tiles that tile the Euclidean plane, we give diagrams illustrating how they tile. We also show several larger tiles whose minimal fundamental domain in any admitted (per…
We demonstrate a flat microlens that exhibits hermaphroditic focusing properties. When the input polarization is parallel (perpendicular) to the liquid-crystal directors, the lens exhibits a positive (negative) focal length. To select the proper polarization, we could rotate the polarizer (or the lens) mechanically or…
The kinetics of the reaction of batches of powdered quartz and sodium carbonate was studied by in situ (23)Na nuclear magnetic resonance (NMR) spectroscopy using a laser-heated probe. We show for the first time that the technique allows one to study solid-state reactions at high temperatures with good time resolution…
The amidase activity of bovine pancreas trypsin in water-soluble complexes with poly(ethylene glycol)-block-poly(alpha,beta-aspartic acid) (PEG-PAA) was evaluated by a colorimetric assay using L-lysine p-nitroanilide as a substrate. The enzymatic reaction of trypsin was accelerated through the complexation with PEG-PA…
The influences of acetic acid addition to Mg‐methoxide on the stability of the precursor and the crystallization behavior of sol–gel‐derived MgO nano‐powders and thin films were investigated using X‐ray powder diffraction, transmission electron microscopy, Fourier‐transformed infrared spectroscopy, and thermogravimetr…
Preparation of Langmuir monolayers of a mixture of trans- and cis-isomers of an azobenzene derivative, 4-[4-[(4-octylphenyl)azo]phenoxy]butanoic acid, results in the segregation of birefringent trans-isomer domains embedded in an isotropic medium of cis-isomers. Brewster angle microscopy observations allow us to ident…
Bio-catalytic preparation, physical and biological properties, and potential utilization of novel Nodax™ copolymers are discussed. Nodax™ is a family of bacterially produced polyesters comprising 3-hydroxybutyrate (3HB) and medium-chain-length 3-hydroxyalkanoate (mcl-3HA) units. The biosynthesis of PHA copolymers invo…
Rigid-tube computations of simple (transverse) shear in crystalline nanotube ropes (CNTRs) reveal that shear modulus and strength increase and decrease with the tube radius, respectively. High modulus to strength ratios suggest that dislocations play a minor role during their plasticity. The computed shear moduli are…
The local structure and electronic properties of Mn in Na doped lanthanum manganites have been investigated by means of Mn-K edge XAFS, at various temperatures ranging from RT to 30 K. The hole content depends on the amount of doping, both with Na which injects two holes per doping atom and with oxygen nonstoichiometr…
Abstract 2,6‐Bis (4‐aminophenoxy) pyridine was prepared via reaction of 4‐aminophenol with 2,6‐dichloropyridine in the presence of potassium carbonate in N ‐methyl‐2‐pyrrolidone (NMP). This pyridine‐based ether diamine was reacted with two moles of trimellitic anhydride to synthesize related diimide‐diacid (DIDA). A h…
A new synthetic route is described that allows the reversible conversion of the inherently insoluble oligo-p-benzamides into soluble materials through the formation of imidoyl chlorides. Syntheses of the corresponding dimer, trimer, and tetramer are reported; these compounds can easily be purified by crystallization a…
Abstract 4,4′‐bis(Phenoxy)diphenyl sulfone (DPODPS) was synthesized by reaction of phenol with bis(4‐chlorophenyl) sulfone in tetramethylene sulfone in the presence of NaOH. Two poly(aryl ether sulfone ether ketone ketone)s (PESKKs) with high molecular weight were prepared by low temperature solution polycondensation…
BRL 42715, C6-(N1-methyl-1,2,3-triazolylmethylene)penem, is an active-site-directed inactivator of bacterial beta-lactamases. The crystal structure of Enterobacter cloacae 908R class C beta-lactamase in complex with BRL 42715, docking, and energy minimization studies explain stereoselectivity of the binding of C6-(het…
The electrochemical behavior of poly(ferrocenyldimethylsilane-b-dimethylsiloxane) (PFDMS-b-PDMS) films deposited on a glassy carbon electrode was investigated by means of cyclic voltammetry (CV). The influences of the solvent, film thickness, temperature, and PDMS block length in PFDMS-b-PDMS on the electrode process…
Gold porphyrins are often used as electron-accepting chromophores in donor-acceptor complexes for the study of photoinduced electron transfer, and they can also be involved in triplet-triplet energy-transfer interactions with other chromophores. Since the lowest excited singlet state is very short-lived (240 fs), the…
Abstract The fracture behavior of biodegradable fiber–reinforced composites as a function of fiber content under different loading conditions was investigated. Composites with different fiber content, ranging from 5 to 20 wt%, were prepared using commercial starch‐based polymer and short sisal fibers. Quasistatic frac…
Surface-enhanced Raman spectra of a single Fe-protoporphyrin IX molecule display drastic fluctuations in frequency and intensity. When analyzed in their temporal evolution, the vibrational modes of the molecule undergo an on-off switching behavior that is shown to follow a Lévy statistics. Such a time dependent proces…
Abstract A series of water‐soluble N‐substituted poly(alkylanilines) (PNAAs) have been enzymatically synthesized with a variety of groups, from methyl to n‐butyl, such as poly( N ‐methylaniline), poly( N ‐ethylaniline), poly( N ‐butylaniline) and poly( N ‐phenylethanolamine). The syntheses were made in the presence of…