Materials Literature
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A new macrocyclic N-bridged species of formula [PcFe–N–FePc](Pc = phthalocyaninato anion, C32H16N82–) has been prepared by reaction of PcFe with NaN3 in α-chloronaphthalene and structurally and electronically characterized by i.r., visible, X-Ray powder, and e.s.r. measurements: one-electron oxidation leads to the cat…
Using a pair of backscattered electron detectors in the scanning electron microscope, images can be produced in which the intensity is dependent solely on the molecular weight of the imaged area, and independent of small fluctuations in topography. The use of this technique with polished, unetched cement sections, rev…
The authors present a method by which the number of steps required for the ultrastructural study of material originally embedded in paraffin can be greatly reduced. The process reduces deparaffinization, post-fixation, and re-embedding to four steps that take little more than 30 min to complete.
A development program is described in which reactor grade Zr-2.5Nb pressure tubes were produced with properties comparable to current reactor tubes but which are expected to show lower in-reactor creep and growth. Lower creep and growth rates would mean smaller axial elongations of tubes in service. Evaluation of the…
Abstract The viscosity behavior of aqueous poly(vinyl alcohol) (PVA)‐borax‐NaCl systems was investigated. The intrinsic viscosity [η] of PVA in borax solution increases with increasing borax concentration. In solutions containing both borax and NaCl, on the other hand, [η] decreases with increasing concentration of Na…
Corrosion inhibitive efficiencies of Biguanide monohydrochloride, Dicyandiamide, Guanyl urea-o-hydrochloride and Biuret have been determined by the gravimetric method. It has been shown that the energy eigen values, and the π-electron distributions of the compounds, obtained using the Hückel method, can offer a very u…
An attempt has been made to separate constituents of marine seston samples: inorganic material, detritus and the algal species, by density gradient centrifugation, without affecting the physiological state of the algae. A relatively inert gradient material, consisting of Percoll, salt and sucrose, was composed. Since…
Phosphomolybdic and a variety of phosphomolybdovanadic acids were examined as reoxidants for the palladium sulphate-catalysed oxidation of but-1-ene to butan-2-one both in the absence and the presence of oxygen. All of these co-oxidants were approximately equally effective in reoxidising Pd0 to PdII but they varied su…
X-ray photoelectron spectroscopy has been used to elucidate the state of chromium in the surface layers of CrHY and stabilized CrSY zeolites. Values of both the binding energy (EB) and the spin–orbit splitting (ΔE) of the Cr 2p level for chromium in the zeolite differ from those of bulk chromium oxide compounds or tho…
High resolution, low temperature photoluminescence spectra of manganese‐doped willemite single crystals have been measured. "Hot" bands on the zero‐phonon lines of the excited state of on inequivalent sites are observed at low Mn concentration between 4 K and 29 K. Their appearance is attributed to vibronic (Ham) quen…
X-ray photoelectron spectroscopy (X.p.s.) has been used to study the chemical nature of the oxide film initially produced on clean uranium metal in oxygen + water-vapour atmospheres. The rate of reaction has been monitored and the nature of the surface film determined. From a consideration of the O 1s and U 4ƒ X.p. sp…
The sensitization domains of three AISI 304 austenitic stainless steels, differing only by their carbon content or grain size, have been determined using the ASTM A 262 Practice E and the EPR tests, in order to study the carbon content and grain size effects on sensitization kinetics in the temperature range 600 to 80…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSynthesis, structure, and magnetic properties of fluoride-bridged copper(II) dimers. Crystal and molecular structures of bis(.mu.-fluoro)bis[tris(3,4,5-trimethylpyrazole-N2)copper(II)] bis(tetrafluoroborate) and bis(.mu.-fluoro)bis[(5-methylpyrazole-N2)bis(3,5-dimethylpyrazo…
Rates of adsorption and desorption, of di-isopropyldithiophosphoric acid and tetraisopropylthioperoxydiphosphate from hexade-cane on to steel, have been measured wing 14C radiolabelled compounds. Concentration, temperature, and stirring dependence have been examined. The adsorption is surface controlled and the kineti…
The maturation process of collagen fibres was investigated by the picro-sirius red/polarization light technique in experimental wound healing, in allyl-alcohol induced subacute and chronic liver fibrosis and in human biopsy material. Evidence was obtained that collagen fibres undergo a rapid maturation in fibrotic pro…
A review is presented on the pitting corrosion of zirconium and Zr alloys when immersed in aqueous solutions at temperatures less than 100 C. The electrochemical methods (potentiokinetic, potentiostatic, and scratch) used to evaluate pitting susceptibility are described briefly. Zirconium is susceptible to pitting in…
The foliated calcite of living scallops (Pectinacea), oysters (Ostreacea), window-pane and jingle shells (Anomiacea) consists of approximately 250 nm thick sheets (folia) formed of subparallel laths joined laterally. The surfaces of these very thin folia are not the basal pinacoid of calcite (0001), as has previously…
Erosion of a glass ionomer cement in acetic (AA), lactic (LA), citric (CA) and hydrochloric acids (HA) was investigated by means of chemical analysis, SEM observation and infrared (IR) spectroscopy.The larger stability constants of the complex between the acid anions and Al or Ca, or the lower the pH of the acid solut…
Variations in the electrical resistivity and in the deviation from Matthiessen’s rule (DMR) during quench-ageing have been observed on low-carbon aluminium-killed steels containing varied amounts of manganese. The DMR is measured by the difference between the resistivities at 273 K and at the liquid-nitrogen temperatu…
The dimeglumine salt of the Gd-DTPA complex has a strong paramagnetic effect and a very low toxicity in animals. This report of its use in human volunteers confirms its low toxicity and indicates its usefulness in the enhancement of signal intensity of the kidney and bladder.