Search results for "ALLOYS"
showing 10 items of 1689 documents
Computational analysis of positron experiments
1984
A number of applications of the calculational scheme developed by Puska and Nieminen (1982-3) are reported and the predictive power of the scheme is substantiated. Effects on positron parameters of relaxation and of N or H impurities in vacancies in Mo are calculated and employed to analyse recent experiments. Predictions pertaining to H decoration of vacancies in Al and Ni suggest the use of positron lifetime studies of these systems. Positron responses to submicroscopic vacancy clusters decorated with Kr and to large Kr bubbles in Cu are calculated and used to analyse recent experiments. To accomplish this the scheme is generalised to incorporate crystals of inert gas. In turn this makes …
Interesting synthetic routes from the reinvestigation of the reaction of the M(CO)6 (M=Cr, Mo and W) species with KOH
1989
Reinvestigation of the reaction of M(CO)6 (M=Cr, Mo or W) with KOH has been found to provide a very convenient route to the K[M2H(CO)10] compounds (M=Cr, Mo or W). The reaction involving Cr(CO)6 yields new potassium derivatives containing [Cr2(CO)10]2− and [HCr(CO)5]− species; also K[Cr2D(CO)10] is produced from the Cr(CO)6/KOD interaction in C2D5OD. The reaction involving two different group 6 metal carbonyls yields [MM′(CO)10(μ-H)]− (MM′=CrMo, CrW or WMo) species as their K+ and PPN+ [bis(triphenylphosphine)iminium] salts.
Temperature- and pressure-dependent structural study of {Fe(pmd) 2[Ag(CN)2 ]2}n spin-crossover compound by neutron Laue diffraction
2014
The effect of pressure (up to 0.17GPa) on the spin-crossover compound {Fe(pmd)2[Ag(CN)2]2} n [orthorhombic isomer (II), pmd = pyrimidine] has been investigated by temperature- and pressure-dependent neutron Laue diffraction and magnetometry. The cooperative high-spin ↔ low-spin transition, centred at ca 180K at ambient pressure, is shifted to higher temperatures as pressure is applied, showing a moderate sensitivity of the compound to pressure, since the spin transition is displaced by ca 140KGPa-1. The space-group symmetry (orthorhombic Pccn) remains unchanged over the pressure-temperature (P-T) range studied. The main structural consequence of the high-spin to low-spin transition is the c…
Solvent free oxidation of primary alcohols and diols using thymine iron(III) catalyst.
2010
In this study, we developed an efficient and selective iron-based catalyst system for the synthesis of ketones from secondary alcohols and carboxylic acids from primary alcohol. In situ generated iron catalyst of thymine-1-acetate (THA) and FeCl(3) under solvent-free condition exhibits high activity. As an example, 1-octanol and 2-octanol were oxidized to 1-octanoic acid and 2-octanone with 89% and 98% yields respectively.
Halloysite based geopolymers filled with wax microparticles as sustainable building materials with enhanced thermo-mechanical performances
2022
This work proposes a novel protocol for the fabrication of halloysite based geopolymers filled with beeswax microparticles obtained from Pickering emulsions. The actual filling of the microwax into the geopolymers has been demonstrated by using several techniques, including thermal analyses, spectroscopies, microscopies and contact angle experiments. According to the morphological and structural investigations, microwax spherical particles (diameter ranging between ca. 3 and 5 μm) have been homogeneously dispersed within the geopolymeric network conferring excellent properties to the hybrid geopolymers in terms of mechanical performances and heat storage capacity although their low content …
Measuring business performance in the metal finishing industry by combining theory with practice
2019
Little attention has been spent on the adaptation and implementation of theoretical Business Performance Measurement (BPM) models to specific industry and company contexts leading to a limited prac...
Thermodynamics of Proton Binding of Halloysite Nanotubes
2016
In this paper, new information on physical and chemical properties of the widely used nanostructured Halloysite mineral are reported. Given that the Halloysite has a tubular structure formed by a variable number of wrapped layers containing Si-OH and Al-OH groups, their proton binding affinity was measured at different ionic strengths and ionic media by means of potentiometric measurements in heterogeneous phase. One protonation constant for the Si-OH groups and two for the Al-OH groups were determined. The protonation constant values increase with increasing of the ionic strength in all the ionic media. This suggests that the presence of a background electrolyte stabilizes the protonated s…
Dependence of enzyme reaction mechanism on protonation state of titratable residues and QM level description: lactate dehydrogenase
2005
We have studied the dependence of the chemical reaction mechanism of L-lactate dehydrogenase (LDH) on the protonation state of titratable residues and on the level of the quantum mechanical (QM) description by means of hybrid quantum-mechanical/molecular-mechanical (QM/MM) methods; this methodology has allowed clarification of the timing of the hydride transfer and proton transfer components that hitherto had not been possible to state definitively. Ferrer Castillo, Silvia, Silvia.Ferrer@uv.es, Silla Santos, Estanislao, Estanislao.Silla@uv.es ; Tuñon Garcia de Vicuña, Ignacio Nilo, Ignacio.Tunon@uv.es
Regioselective C–H amination of free base porphyrins via electrogenerated pyridinium-porphyrins and stabilization of easily oxidized amino-porphyrins…
2020
Four free base aminoporphyrins were synthesized in two steps via regioselective anodic nucleophilic substitution with pyridine followed by ring opening of the electrogenerated pyridinium with piperidine. The X-ray crystallographic structure of the unstable 2-aminotetraphenylporphyrin was solved. Protonation of this latter compound leads to the stable diiminium porphyrin salt.
Sol-gel produced humidity sensor
1993
Abstract The sol-gel produced polycrystalline Prussian Blue thick films as planar humidity sensors have been investigated by impedance spectroscopy. The equivalent circuit used allows simulation in all the investigated r.h. range (10–100%). The region of changes of sample resistance is about five orders, which is enough for high measuring sensitivity.