Materials Literature
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Treatment of magnesium or zinc porphyrins with thallium(III) trifluoroacetate, followed by an acidic work-up affords oxophlorins in high yield. The oxophlorin oxygen atom is shown to be trifluoroacetate-derived by the isolation of meso-trifluoroacetoxyporphyrins as stable intermediates; a radical mechanism is suggeste…
A mathematical model is proposed to treat the transient response of a disk electrode to a change in the applied current. The analysis reduces to a well‐defined boundary value problem, which yields solutions in terms of newly defined eigenfunctions. The results allow the determination of time constants characteristic o…
Protoporphyrin IX dimethyl ester acts as a diene in Diels–Alder additions with dimethyl acetylenedicarboxylate and with tetracyanoethylene. The copper(II) complex of octaethylporphin reacts with ethyl diazoacetate to yield mainly two isomeric chlorins formed by carbene addition to the cross-conjugated double bonds on…
In comparison with hen egg white lysozyme, goose lysozyme is known to be aberrant in both its structure and its enzymatic behavior in the presence of polymers of N-acetylglucosamine or cell suspensions of Micrococcus luteus. Our chemical studies show, however, that like the hen enzyme, goose lysozyme has muramidase ac…
The rate of corrosion and total corrosion of mild steel in the presence of chemically prepared ferrous sulphide has been studied. The mild steel appears to corrode by a first order reaction. Continued high corrosion rates are observed in experiments where ferrous sulphide is added semi-continuously. Approximately 10 m…
The dependence of the etch rates of vapor‐deposited binary borosilicate, phosphosilicate, and arsenosilicate glasses on glass composition and per cent buffered HF ( 1 part 48 % HF to 10 parts 40 % NH 4 F ) in water are presented. The etch rates of these doped glasses generally increase with increasing dopant oxide con…
Strength and ductilily of two-IJhase iron aLLoys with a ductile second IJhase IHesent are studied. The aLLoys used in this investigation are Fe-C r-N i aLLoys com/Josed of austenite and ferrite , Fe-N i-C aLLoys com/Josed of austenite alld martensite, and Fe-C aLLoys comlJosed of ferrite and lIIartensite, wilh Ilze se…
Shallow range distributions are altered significantly by diffusion and surface erosion. It will be shown here that the simultaneous processes of implantation, diffusion, and surface erosion can be described by a second order differential equation which is mathematically tractable and yields general results in terms of…
The chromium‐depletion theory of intergranular corrosion has been confirmed for a ferritic stainless steel. The potential range over which intergranular attack occurs is limited by the passivation potential of the matrix and that of chromium‐free iron. The concentration of chromium in the depleted zone is less than 5%…
The formation of particulate TiO2 has been studied by the addition of small quantities (10–5–10–3 mol fraction) of TiCl4 vapour to a lean CO + O2+ N2 flame with a maximum temperature of about 1400°C. Measurements of TiCl4 concentration have been made as a function of height (residence time) by u.-v. absorption spectro…
For certain conditions, alloys composed of metals of different nobility anodically dissolve without noticeable preferential dissolution of the less noble metal (simultaneous dissolution). In principle, an induction period of disproportionate dissolution of the less noble metal should precede simultaneous (nonselective…
Pitting potential measurements were performed by potentiodynamic scanning at 200 mV/hr in and in , each saturated with nitrogen. Over the entire temperature range studied, 1°–70°C, molybdenum additions up to the limit of solid solubility caused a continuous increase in the pitting potentials of 18% Cr ferritic stainle…
Partially ordered polyarnide-hydrazides were produced by the poly condensation of diacid chlorides with aminobenz-hydrazides, the order that results being a consequence of the considerably more rapid reaction of a diacid chloride with the hydrazide group in competition with the aromatic amine group of the aminobenzhyd…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPhotochemistry of .alpha.-pyrone in solid argonRichard G. S. Pong and James S. ShirkCite this: J. Am. Chem. Soc. 1973, 95, 1, 248–249Publication Date (Print):January 1, 1973Publication History Published online1 May 2002Published inissue 1 January 1973https://pubs.acs.org/doi…
A detailed investigation has been made regarding the variation in internal friction and Young's modulus with temperature in manganese–copper alloys containing 11.74–26.08 wt.-% Cu. It was confirmed that the transformation temperature for the fct → fcc reverse martensitic transformation in quenched specimens is reduced…
The effect of terminal alkyl and alkoxy substituents on the mesomorphic properties of p-alkylphenyl p-alkylbenzoates, p-alkylphenyl p-alkoxybenzoates, p-alkoxyphenyl p-alkylbenzoates, and p-alkoxyphenyl p-alkoxybenzoates was studied. It was found that, with relatively few experiments, one could make reasonable predict…
SummaryThe mechanism by which coloured films form on stainless steel when immersed in a solution containing chromic and sulphuric acids at 70°C has been studied. The variation of the potential of the steel with time of immersion in 2·5M CrO3 + 5M H2SO4 was measured and the weight change of the metal and the thickness…
Binary chromium(IV) alkyls, CrR4, R = CH2CMe3, CH2CMe2Ph, CH2CPh3, and CH3, have been prepared and characterised by electronic, i.r. and e.s.r. spectroscopy. The electronic and magnetic properties of tetrahedral chromium(IV) compounds are discussed.
The E.S.R. spectrum of an electron irradiated, type IIa diamond has been studied after it had been annealed at various temperatures up to 1400°C. Six sets of lines were identified following anneals in the temperature range 700°C–1000°C. They all arose from centres with ⟨110⟩ symmetry and a spin of 1. The centres are t…
The results of wide- and small-angle X-ray studies on bulk vulcanizates of natural rubber are described. At room temperature no discrete X-ray peaks occur at small angles, even for highly strained (700%) specimens for which a significant degree of crystallinity is present at room temperature. Below the isotropic melti…