Materials Literature
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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…
The structural relaxation caused by the plastic deformation of polymer glasses is not yet fully understood. In particular, the size scale of the localized plastic relaxation events is currently unknown. In this work, the effect of molecular entanglement density on the shear activation volume of glassy polymers has bee…
We have examined the effect of monomer structure on amine−anhydride reactions at a polymer−polymer interface. The thermodynamic interaction parameter χ was varied by changing the backbone chemical structure, holding molecular weight constant. To eliminate the effects of mixing, experiments were performed with bilayer…
A magnetostructural correlation (conformational electron spin exchange modulation) within an isostructural series of biradical complexes is presented. X-ray crystal structures, variable-temperature electron paramagnetic resonance spectroscopy, zero-field splitting parameters, and variable-temperature magnetic suscepti…
The direct oxyfunctionalization of a model polyolefin, polyethylene- alt -propylene (PEP), was achieved utilizing a straightforward, mild process. In the presence of a manganese complex, manganese meso- tetra-2,6-dichlorophenylporphyrin acetate (Mn(TDCPP)OAc), imidazole, a phase transfer agent, and potassium peroxymon…
We have fabricated a p–n junction, consisting of p-type manganite (La0.7Sr0.3MnO3) and n-type ZnO layers grown on sapphire substrate. This junction exhibits excellent rectifying behavior over the temperature range 20–300 K. Electrical characteristics of La0.7Sr0.3MnO3 (LSMO) film in this heterostructure are found to b…
AlN films grown by gas-source molecular beam epitaxy were doped with different levels of Mn during growth. High resolution x-ray diffraction characterization revealed good crystallinity in single phase material, with lattice constant decreasing with increasing Mn concentration. Single phase AlMnN was found to be p typ…
The biosynthetic pathway of medium-chain-length (MCL) polyhydroxyalkanoates (PHAs) from fatty acids has been established in fadB mutant Escherichia coli strain by expressing the MCL-PHA synthase gene. However, the enzymes that are responsible for the generation of (R)-3-hydroxyacyl coenzyme A (R3HA-CoAs), the substrat…
As a result of a pseudosymmetry search, the double perovskite compounds Sr 2 MWO 6 (M = Ni, Zn, Co, Cu) were identified as good candidates for presenting Landau-type phase transitions at high temperatures. In the present work, the phases observed at different temperatures are reported and the phase transitions are dis…
The causality of waves propagating in a double-negative (DNG) metamaterial (epsilon (r)<0 and mu(r)<0) has been investigated both analytically and numerically. By considering the one-dimensional electromagnetic problem of a pulsed current sheet radiating into a DNG medium, it is shown that causality is maintained in t…
The transformation of nanodiamonds into carbon onions, and vice versa, has lead to the introduction of a new intermediate phase of carbon, coined ``bucky diamond,'' with a diamond core encased in an onion-like shell. Using a model based on the atomic heat of formation to describe the phase stability of carbon nanopart…
Synchrotron-based time-resolved x-ray diffraction (TR-XRD), x-ray absorption near edge spectroscopy (XANES), Raman spectroscopy (RS), and first-principles density functional (DF) calculations were used to study the structural and electronic properties of Ce–Ca mixed-metal oxides. The XRD results and DF calculations sh…
The magnetic and electronic structure of strontium hexaferrite SrFe 12 O 19 has been investigated using density functional theory within the local spin density approximation. The calculations show that in this ferrite all the Fe 3+ ions are fully spin polarized with S = 5/2. The electronic structure of this ferrite is…
Time-resolved reflectivity is employed as an in situ diagnostic in thermal chemical vapor deposition of vertically aligned arrays of multiwall carbon nanotubes (VAA–MWNT). Fabry–Ṕerot interference fringes and attenuation of a reflected HeNe laser beam are used to measure the length of VAA–MWNT throughout the first 3–8…
The effect of surface composition and wettability on the adsorption of human serum albumin (HSA) was studied. Self-assembled monolayers (SAMs) containing mixtures of longer chain methyl- and shorter chain hydroxyl-terminated alkanethiols on gold were used to produce a range of surfaces with different wettabilities and…
The levels of the 4f n −1 5d configuration of Ce 3+ ( n = 1), Pr 3+ ( n = 2), and Tb 3+ ( n = 8) in compounds are compared with each other. A model is presented that, by means of energy shift operations performed on the five 5d levels of Ce 3+ , reproduces the energies of those for Pr 3+ and Tb 3+ . Using Tb 3+ data,…
The hyperthermophilic Archaeon Sulfolobus solfataricus metabolizes glucose by a non-phosphorylative variant of the Entner-Doudoroff pathway. In this pathway glucose dehydrogenase and gluconate dehydratase catalyze the oxidation of glucose to gluconate and the subsequent dehydration of gluconate to 2-keto-3-deoxyglucon…
We outline the current state of experimental study and basic ideas for describing phase transitions in topologically disordered condensed matter, such as liquids and amorphous solids. Reviewing briefly the study of molten elementary substances under pressure, we pay primary attention to the results for liquid Se, S, a…
The affinity of maltose-binding protein (MBP) for maltose and related carbohydrates was greatly increased by removal of groups in the interface opposite the ligand binding cleft. The wild-type protein has a KD of 1200 nM for maltose; mutation of residues Met-321 and Gln-325, both to alanine, resulted in a KD for malto…