Metalloporphyrins as chemical mimics of cytochrome P-450 systems
Abstract
Materials Literature
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Cationic Ring-Opening Polymerization of Cyclosiloxanes Initiated by Electron-Deficient Organosilicon Reagents 1a
The cationic ring-opening polymerization of octamethylcyclotetrasiloxane initiated by R 3 SiH−Ph 3 C + B(C 6 F 5 ) 4 - (trityl TPFPB) in the absence of protic acids has been investigated. Mechanistic studies demonstrate that the polymerization proceeds by a single “long-lived” oxonium ion end. This novel polymerizatio…
Dynamics of the three methionyl side chains of Streptomyces subtilisin inhibitor. Deuterium NMR studies in solution and in the solid state
Streptomyces subtilisin inhibitor (SSI) contains three methionine residues in a subunit: two (at positions 73 and 70) in the crucial enzyme-recognition sites P1 and P4, respectively, and one (Met 103) in the hydrophobic core. The motions of the side chains of these three Met residues and the changes in mobility on bin…
Synthesis and characterization of various MgO and related systems
Various magnesium oxide catalysts have been prepared by thermal treatment of two different precursors: Mg(OH)2 and Mg5(OH)2(CO3)4. An additional system based on MgO and doped with B2O3 was also prepared. The textural and acid–base properties of the catalysts were investigated. The synthesized solids were characterized…
Application of a coupled-integral-equations technique to ridged waveguides
Cut-off frequencies of all TE and TM modes of a ridged rectangular waveguide are accurately determined using a coupled-integral equations technique (CIET). The technique analyzes both symmetric and asymmetric situations in one step. Basis functions, which include the edge conditions and mirror images in the waveguide…
Computational aspects of a softening plasticity model for plain concrete
Several computational aspects of the fracture energy based softening plasticity model for plain concrete are considered. A need for a more robust stress return strategy is identified, as the basic closest point projection algorithm leads to regions of nonconvergence, associated with zones of high curvature near the co…
Differential Charging in XPS. Part I: Demonstration of Lateral Charging in a Bulk Insulator Using Imaging XPS
Recent literature has drawn a distinction between charging across the surface (lateral differential charging) and charging with depth (vertical differential charging) for insulating samples. In this study, differential charging in a bulk insulator was investigated using imaging and small-area spectra acquired with a m…
Effects of Tween 20 on the desorption of proteins from polymer surfaces
The effects of Tween 20 on the desorption of proteins from polyethylene and polyurethane were studied, using single protein solutions of the human proteins fibrinogen (Fb), immunoglobulin G (IgG), serum albumin (HSA), high density lipoproteins (HDL), and plasma. The surfactant may partly or even completely desorb the…
Examination of Fatty Acid Exchanged Layered Double Hydroxides as Supports for Photochemical Assemblies
The incorporation of titanium oxide into the interlayers of a myristic acid exchanged lithium aluminum layered double hydroxide was done by partitioning of titanium butoxide into the interlayer, followed by hydrolysis under ambient conditions. Upon excitation with near-ultraviolet radiation in the presence of viologen…
Study of thermal decomposition mechanism of the Fe/sub 17/Sm/sub 2/N/sub 3/ phase
We studied the high temperature decomposition mechanism for the Fe/sub 17/Sm/sub 2/N phase using several different experimental techniques, as thermomagnetic and thermogravimetric analyses. Our results show that the decomposition occurs in a two step scheme. In the first reaction we hare the formation of SmN and a sol…
Dielectric and Mechanical Relaxation in the Blends of a Polymer Liquid Crystal with Polycarbonate
Bisphenol A polycarbonate (PC) and PET/0.6PHB polymer liquid crystal (PLC), where PET is poly(ethylene terephthalate), PHB is p -hydroxybenzoic acid, and 0.6 is the mole fraction of PHB in the copolymer, were studied along with their blends from the PC side up to 20 wt % PLC. Dielectric relaxation in the range 10 -2 −…
Fracture Toughness of Zircaloy Cladding Tubes
The fracture toughness of Zircaloy-2 cladding has been estimated by means of the recently developed pin-loading (PL) tension test. Axially notched ring specimens, cut directly from different cladding (annealed, cold-worked, hydrided, and irradiated), have been tested in a way similar to that used for compact tension s…
The effect of ultrasound on Escherichia coli viability
The effect of continuous-wave ultrasound on the viability of Escherichia coli HB101 was assessed using a 20 kHz ultrasonic processor. A standardised cell suspension of fixed concentration was used to investigate the influence of different physical and environmental conditions on ultrasound susceptibility. Cell viabili…
Poly[alkyl methacrylate-b-butadiene-b-alkyl methacrylate] Triblock Copolymers: Synthesis, Morphology, and Mechanical Properties at High Temperatures
Block copolymers of the ABA type, where B is polybutadiene (PBD) and A is poly(ethyl methacrylate) (PEMA), poly( tert -butyl methacrylate) (P-t-BMA), poly(methyl methacrylate) (PMMA), or poly(isobornyl methacrylate) (PIBMA), have been successfully synthesized by sequential anionic polymerization of butadiene and metha…
Synthesis, Characterization and Properties of Polyacrylamide‐Starch Composites
Abstract Polyacrylamide‐starch composite was prepared by polymerization of maize or rice starch with acrylamide (Aam) using potassium permangante/citric acid initiation system. Major factors affecting the polymerization reaction were studied with a view to discover appropriate conditions for preparation of the composi…
Hyperbranched Poly(4-Acetylstyrene) by Ruthenium-Catalyzed Step-Growth Polymerization of 4-Acetylstyrene
Treatment of 4-acetylstyrene (an AB 2 monomer) with dihydridocarbonyltris(triphenylphosphine)ruthenium leads to hyperbranched poly(4-acetylstyrene) whose structure has been determined by 1 H and 13 C NMR spectroscopy. The hyperbranched material has been characterized by GPC, IR, UV, TGA, DSC, and elemental analysis. P…
High-Tc Magnets in a Series of Substituted Pyridinium−FePS3 Layered Intercalates
A series of new FePS 3 layered intercalation compounds having the general formula Fe 1 - x PS 3 G 2 x (where G stands for a monocation) has been prepared by cation exchange with several pyridinium derivatives. The occurrence of intralayer Fe 2+ vacancies is evidenced by 57 Fe Mössbauer spectroscopy. The magnetic prope…
New Metal Oxamates as Precursors of Low-Dimensional Heterobimetallics
The goal of this work was to synthesize new molecular bricks which could be used as precursors of heterobimetallic low-dimensional compounds. Along this line, four compounds have been synthesized and structurally characterized, namely (NBu(4))(2)[Ni(Cl(2)opba)] (1), (NBu(4))(2)[Cu(Cl(2)opba)] (2), (NBu(4))(5)[Mn(Cl(2)…
Interfacial Interactions between Polyethylene and Polypropylene and Some Ethylene-Containing Copolymers
Annealed interfaces between high-density polyethylene (HDPE), low-density polyethylene (LDPE), and polypropylene (PP) and some ethylene- co -vinyl acetate (EVA) and ethylene- co -acrylic acid (EAA) copolymers were examined using optical microscopy, scanning electron microscopy (SEM), and electron microprobe analysis.…
Pressure-Induced Spin-State Crossovers in Six-Coordinate FeIILnL‘m(NCS)2Complexes with L = L‘ and L ≠ L‘: A XANES Investigation
The pressure-induced iron(II) high-spin (HS) → low-spin (LS) conversion has been investigated, by near-edge X-ray absorption (XANES) spectroscopy at room temperature, in a number of parent six-coordinate complexes of the type FeL n L‘ m (NCS) 2, viz. Fe(phen) 2 (NCS) 2 form I ( 1 ) and form II ( 2 ), Fe(py) 2 bpym(NCS…