Materials Literature
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The grain structure in lamellar block copolymer samples undergoing a disorder-to-order transition was studied by a combination of depolarized light scattering (DPLS) and transmission electron microscopy (TEM). The 4-fold symmetry of the DPLS profiles indicated the presence of anisotropic grains. A pattern recognition…
Fet3p is a multicopper oxidase that uses four copper ions (one type 1, one type 2, and one type 3 binuclear site) to couple substrate oxidation to the reduction of O(2) to H(2)O. The type 1 Cu site shuttles electrons between the substrate and the type 2/type 3 Cu sites which form a trinuclear Cu cluster that is the ac…
Using ultraviolet photoelectron spectroscopy (UPS), temperature programmed desorption (TPD), and periodic density functional theory (DFT), we have investigated the oxidation chemistry of diamond (111) surface following its exposure to atomic oxygen generated from a remote radio frequency discharge. Partial O uptake oc…
In the pharmaceutical industry, a vast number of compounds are produced by solution crystallization, making the design and development of such processes of critical importance. The kinetics of crystal growth and nucleation, the fundamental mechanisms of a solution crystallization process, are strongly dependent on sup…
Polymer-on-polymer stamping, the direct transfer of polyelectrolytes to oppositely charged surfaces, has been used to create alternate regions of “plus/minus (+/−)” charge on surfaces for the fabrication of colloidal particle arrays. Here, new approaches are also presented to create two types of smaller-scale patterns…
Citrate-capped gold nanoparticles as well as planar gold surfaces can be efficiently grafted with a covalently attached polymer monolayer a few nanometers thick, by simple contact of the metal surface with dilute aqueous solutions of hydrophilic polymers that are end-capped with disulfide moieties, as shown by UV/vis…
The kinetics of bulk polymerization of 6-, 7-, 9-, 12-, 13-, 16-, and 17-membered lactones initiated with a zinc 2-ethylhexanoate/butyl alcohol system at 100 °C was studied and compared with that of lipase-catalyzed polymerization. Instantaneous concentrations of the lactone monomers were determined on the basis of th…
Dilute solutions of strongly charged polymer electrolytes undergo, upon addition of multivaltent salt to the solutions, a phase transition from extended conformations to collapsed or bundled ones. Upon further addition of salt they experience a second transition, a redissolution back into extended conformations. This…
Raspberrylike hybrid organic−inorganic materials consisting of spherical silica beads supporting smaller polystyrene particles were prepared through a heterophase polymerization process. In a first step, micrometer-sized silica particles were synthesized according to procedures inspired from the literature. In a secon…
The fluorescence of the water-soluble anionic conjugated polymer, poly[lithium 5-methoxy-2-(4-sulfobutoxy)-1,4-phenylenevinylene] (MBL-PPV), is quenched in dilute aqueous solution by cytochrome c, a small, naturally occurring electron-transfer protein. The large value obtained for the Stern-Volmer constant (K(sv) = 3.…
We report here on the structural characterization of polyelectrolytes multilayer films formed by poly( l -glutamic acid) and poly( l -lysine) (PGA/PLL). The growth of this system is compared to that of poly(styrenesulfonate)/poly(allylamine hydrochloride) (PSS/PAH) multilayers by means of in situ atomic force microsco…
The low temperature alloying of copper and nickel nanoparticles synthesized in a fatty acid film by a novel ion-entrapment process is described. Nanoparticles of copper and nickel were grown in thermally evaporated stearic acid films by immersion of the film sequentially in solutions containing Cu2+ ions and Ni2+ ions…
Starch and urea are used as fillers, owing to their good mechanical and degradable properties, in linear low density polyethylene matrix. Composites of varying amount of starch and urea composition are prepared. Various properties like tensile strength, elongation at break, Young's modulus, shore-D hardness, and water…
The enzyme L-rhamnulose-1-phosphate aldolase catalyzes the reversible cleavage of L-rhamnulose-1-phosphate to dihydroxyacetone phosphate and L-lactaldehyde. It is a homotetramer with an M(r) of 30 000 per subunit and crystallized in space group P3(2)21. The enzyme shows a low sequence identity of 18% with the structur…
A new route to a pentaerythritol-based tetraamine is delineated and subsequently contrasted to a previous report. Access to the pure tetraamine is facilitated by the smooth reduction of its tetraazide precusor. Characterization includes the preparation of a 4:1 Zn-tetraphenylporphyrin/tetraamine complex.
Hong et al. (1) reported that they had successfully produced arrays of single-crystal silver nanowires (of diameter 0.4 nm) formed in an ambient solution phase inside the pores of self-assembled calix[4]hydroquinone (CHQ) nanotubes. These nanowires, it was suggested, existed as coherently oriented three-dimensional ar…
The structures of Bacillus intermedius ribonuclease (binase), an extracellular 109-residue enzyme, and its complexes with 3'GMP and sulfate ions were solved at 1.65 and 2.0 A, respectively. The structures were refined using REFMAC. The crystal of free binase belongs to the space group C2, whereas the crystals of compl…
A structure of native concanavalin A (ConA), a hardy perennial of structural biology, has been determined in a dimeric crystal form at a resolution of 1.56 A (space group C222(1); unit-cell parameters a = 118.70, b = 101.38, c = 111.97 A; two molecules in the asymmetric unit). The structure has been refined to an R(fr…
The collagen model peptide T1-892 includes a C-terminal nucleation domain, (Gly-Pro-Hyp)(4), and an N-terminal (Gly-X-Y)(6) sequence taken from type I collagen. In osteogenesis imperfecta (OI) and other collagen diseases, single base mutations often convert one Gly to a larger residue, and T1-892 homologues modeling s…
The interaction-site-density-fluctuation correlators, the dipole-relaxation functions, and the mean-squared displacements of a system of symmetric dumbbells of fused hard spheres are calculated for two representative elongations of the molecules within the mode-coupling theory for the evolution of glassy dynamics. For…