Materials Literature
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We show that epd (gapB) mutants lacking an erythrose 4-phosphate (E4P) dehydrogenase are impaired for growth on some media and contain less pyridoxal 5'-phosphate (PLP) and pyridoxamine 5'-phosphate (PMP) than their epd+ parent. In contrast to a previous report, we found that gapA epd double mutants lacking the glycer…
The magnitudes and orientations of the principal elements of the 15 N chemical shift and 1 H− 15 N dipolar coupling interaction tensors pertaining to the glycine residue in 15 N -acetyl glycine (NAG) and [ 15 N-Gly]collagen were determined by the analysis of one-dimensional dipolar chemical shift powder patterns. A on…
Isothermal crystallizations from the melt of samples of syndiotactic polypropylene having different degrees of syndiotacticity have been performed. The thermal behavior and the structural features of the melt-crystallized samples have been analyzed by differential scanning calorimetry and X-ray diffraction. According…
A disordered three-dimensional perovskite phase SrTa2-xNbxO6 (x = 0, 0.2, 0.4) is formed by topochemical dehydration of acid-exchanged Ruddelsden Popper compounds K2SrTa2-xNbxO7. The metastable perovskite is a stoichiometric precursor to the structurally unrelated, stable tetragonal tungsten bronze phase. Dehydration…
Chitosan fibers were wet spun from a 6% by weight chitosan in 3% by volume acetic acid solution. The fibers were collected as a 20 filament yarn intended for use as a chaff substrate. The yarn had to be sufficiently dry following spinning to allow for winding and subsequent separation of the filaments. Drying of the y…
Temperature dependence of absorption spectra for thin films of doped manganites ${R}_{0.6}{\mathrm{Sr}}_{0.4}{\mathrm{MnO}}_{3},$ where $R$ is a rare-earth atom, has been investigated by systematically changing the averaged ionic radius $〈{r}_{A}〉$ of perovskite $A$ site. We have observed a specific absorption band at…
The irreversible polymerization of a monomer liquid has been studied by molecular-dynamics simulation in two and three dimensions. The growth process is studied under good solvent conditions in the dilute regime and up to semidilute and concentrated regimes. In the dilute regime we observe a reaction limitation due to…
We show that photoluminescence from a thin silicon-on-insulator (SOI) layer with a thickness of about 0.1 μm excited by ultraviolet (UV) light originates from the recombination of electrons and holes in their condensed phase. The UV excitation increases the density of electrons and holes in the SOI layer, since the UV…
Mesoporous silica, SBA-2, has been investigated by using high-resolution transmission electron microscopy supported by computer image simulations. The complete pore structure connecting the discrete supercages of which the silica is composed has been determined. In addition, unexpected well-defined cubic-hexagonal (po…
A tight-binding model is used to investigate confinement and shape effects on the optical absorption spectrum of CdSe nanocrystals up to 5 nm diam. The effects of size dispersion are studied and we show that to simulate the spectrum of a collection of nanocrystals it is not always sufficient to broaden inhomogeneously…
The voltage and film composition dependence of leakage currents of ferroelectric SrBi2Ta2O9 thin films, sandwiched between Pt has been studied. Schottky emission dominated the leakage current at voltages above the ohmic conduction regime, while space charge limited currents (SCLC), for which the observed temperature d…
Nitrogenated and hydrogenated amorphous carbon (a-C:H:N) films have been deposited by a plasma beam source using a gas mixture of C2H2, Ar and N2. The Ar/C2H2 ratio is kept constant at a ratio of 3, with the nitrogen flow allowed to vary. Nonnitrogenated films, with Ar/C2H2 ratios of 3 and 6 were also deposited and an…
We report in situ measurements of four-probe dc resistance (R) and thermopower (S) of Cs- and K-doped single-wall carbon nanotube (SWNT) mats as a function of a doping and temperature (T). With increasing dopant exposure, the mat resistance has been found to first decrease and then increase, exhibiting a minimum for o…
We study the conductance of carbon nanotube wires in the presence of disorder, in the limit of phase-coherent transport. For this purpose, we have developed a simple numerical procedure to compute transmission through carbon nanotubes and related structures. Two models of disorder are considered, weak uniform disorder…
Surfactant-mediated transport of insoluble, hydrophobic polymers can be exploited to produce a novel interleaved metal oxide/polymer composite containing poly(p-phenylene). The synthetic route is illustrated in the scheme, whereby a surfactant bilayer between the MoO3 layers is displaced by the PPP/surfactant dispersi…
New AB 2 type monomers, with a various number of phenylene units, were prepared and converted to hyperbranched poly(ether ketones) by polymerization. Four kinds of AB 2 type monomers, 4-hydroxy-3‘,5‘-bis(4-fluorobenzoyl)-biphenyl, 1, 4-hydroxy-3‘‘,5‘‘-bis(4-fluorobenzoyl)- p -terphenyl, 2, 4-hydroxy-3‘‘‘,5‘‘‘-bis(4-fl…
Two series of thermoplastic polyurethane elastomers [poly(propylene glycol) (PPG) based PP samples and poly(oxytetramethylene)glycol (PTMG) based PT samples] were synthesized from isophorone diisocyanate (IPDI)/1,4-butanediol (BD)/PPG and IPDI/BD/PTMG. The IPDI/BD based hard segments contents of polyurethane prepared…
Ln 2 CuSnO 6 (Ln = Pr, Nd, and Sm) and La 2 CuZrO 6 have been stabilized in the same layered double perovskite structure as La 2 CuSnO 6 at high pressures of 6−8 GPa. Their crystal structures and magnetic properties were investigated. Replacement of La 3+ by smaller lanthanide ions and Sn 4+ by larger Zr 4+ increased…
The biodegradable poly(L-lactide-co-trimethylene carbonate) [poly(LLA-co-TMC)] was synthesized by molten ring-open copolymerization and the structure and properties of the copolymer were investigated by GPC, NMR, FTIR, DSC, and Instron testing. The copolymer with a higher LLA content had a higher initial molecular wei…
Optical conductivity spectra of single crystals of the perovskite-type ${3d}^{1}$ metallic alloy system ${\mathrm{Ca}}_{1\ensuremath{-}x}{\mathrm{Sr}}_{x}{\mathrm{VO}}_{3}$ have been studied to elucidate how the electronic behavior depends on the strength of the electron correlation without changing the nominal number…