Materials Literature
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Abstract This paper addresses pipeline conditions leading to a protective corrosion product scale. The special case of Top-Of-Line (TOL) corrosion will be considered in detail. Methods for TOL corrosion rate prediction are discussed and compared with new and old experimental data. Data best agree with the so-called ir…
Abstract A comparison is made of the characteristics of the two forms of stress corrosion cracking in pipelines, i.e. the commoner form involving intergranular cracking due to the presence of a relatively concentrated carbonate-bicarbonate solution, against the transgranular cracking that is engendered by a dilute, lo…
Elevated hydrostatic pressure has been used to increase catalytic activity and thermal stability of alpha-chymotrypsin (CT). For an anilide substrate, characterized by a negative value of the reaction activation volume (DeltaV( not equal)), an increase in pressure at 20 degrees C results in an exponential acceleration…
Polyhydroxyalkanoates (PHAs) are polyesters of hydroxyalkanoates (HAs) synthesized by numerous bacteria as intracellular carbon and energy storage compounds and accumulated as granules in the cytoplasm of cells. More than 80 HAs have been detected as constituents of PHAs, which allows these thermoplastic materials to…
Small-angle neutron scattering has been used to determine the rate constants for transesterification reactions between hydrogenous and deuterated poly(ethylene terephthalate)s. Intimate mixtures of the two polymers at a weight fraction composition of 0.5 were pressed into plaques and heated for a range of times at tem…
A complete set of 13 C kinetic isotope effects were determined for the thermal decarboxylation of 1,3-dimethylorotic acid and compared with theoretically predicted isotope effects for decarboxylation via either O-2 or O-4 protonated pathways. The best correspondence of experimental and calculated isotope effects is fo…
Two new one-dimensional compounds, trans-[Mn(4-bzpy)2(N(CN)2)2]n (1) and cis-[Mn(bpy)(N(CN)2)2]n (2), have been synthesized and studied from a magnetic point of view (4-bzpy = 4-benzoylpyridine; bpy = 2,2'-bipyridyl). The crystal structures of 1 and 2 have been solved. Compound 1 crystallizes in the monoclinic system,…
The Escherichia coli bifunctional P-protein, which plays a central role in L-phenylalanine (Phe) biosynthesis, contains distinct chorismate mutase (CM) and prephenate dehydratase (PDT) domains as well as a regulatory (R) domain for feedback control by Phe. To elucidate the catalytic mechanism of PDT in the P-protein,…
Using atomistic pseudopotential wave functions, we calculate the electron and hole addition energies and the quasi-particle gap of InAs quantum dots. We find that the addition energies and the quasi-particle gap depend strongly on the dielectric constant ε out of the surrounding material, and that when ε out is much s…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTRole of Cation Size in the Energy of Electron Transfer to 1:1 Polyoxometalate Ion Pairs {(M+)(Xn+VW11O40)}(8-n)- (M = Li, Na, K)Vladimir A. Grigoriev, Craig L. Hill, and Ira A. WeinstockView Author Information Department of Chemistry, Emory University Atlanta, Georgia…
Electronic excitation energies of 16 azobenzene dyes have been calculated by ab initio methods within the second-order polarization propagator approximation (SOPPA). Good agreement with expriment is found for the lowest singlet and triplet states for both the trans - and cis -azobenzene molecules. The differences are…
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The assembled structure of the heptane bolaamphiphile, bis( N -α-amido-glycylglycine)-1,7-heptane dicarboxylate, displays a sensitivity to the acidity of a solution. At pH 4, the heptane bolaamphiphile grows to a crystalline tubule in two weeks. At pH 8, a helical ribbon structure is formed in one week. The degree of…
In order to describe the recently observed effect of current induced magnetization reversal in magnetic nanostructures, the thermokinetic theory is applied to a metallic ferromagnet in contact with a reservoir of spin polarized conduction electrons. The spin flip relaxation of the conduction electrons is described the…
Resonance Raman, ESR, and UV−vis−NIR techniques were used to characterize the secondary doping process in polyaniline (PANI). Experimental results obtained with the first two techniques showed the transformation of diamagnetic quinoid segments into radical semiquinone units while UV−vis−NIR experiments showed the incr…
The catalytic degradation of high-density polyethylene to hydrocarbons was studied over different zeolites. The product range was typically between C 3 and C 15 hydrocarbons. Distinctive patterns of product distribution were found with different zeolitic structures. Over large-pore ultrastable Y, Y, and β zeolites, al…
The non-equilibrium behaviour of concentrated colloidal dispersions is studied using Stokesian Dynamics, a molecular-dynamics-like simulation technique for analysing suspensions of particles immersed in a Newtonian fluid. The simulations are of a monodisperse suspension of Brownian hard spheres in simple shear flow as…
The phase diagram of the blends of a diblock copolymer (A−B) and a random copolymer (ABR) is constructed by the modified confined-chain model developed earlier where the morphology of A−B block copolymer is lamellae and the composition of ABR random copolymer is close to that of A−B. These theoretical results predict…
The phase transitions in two liquid crystalline polyesters have been studied by diffraction techniques employing synchrotron radiation. The two polyesters, derived from p,p ‘ -bibenzoic acid and 3-methyl-1,6-hexanediol, only differ on the optical activity of the chiral spacer: both the active and racemic polymers have…
The response of organic polymers and proteins including poly(methyl methacrylate) (PMMA) and the protein bovine serum albumin (BSA) to a short duration 4.5 GPa shock pulse, termed a “nanoshock”, is studied using ultrafast coherent Raman spectroscopy (CARS) to monitor density-dependent vibrational frequency shifts of a…