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Butamben (butyl p-aminobenzoate) has been formulated to provide long-acting treatment for chronic pain. The suspension, which contains poly(ethylene glycol) and polysorbate 80, was found to yellow under ambient conditions if not adequately protected from oxygen. The impurity responsible for the color was isolated and identified on the basis of nuclear magnetic resonance spectroscopy and mass spectrometry. The compound is an oxalamidine, which is formally the condensation product of oxalic acid with four equivalents of butamben, and may be formed by the reaction of butamben with an oxidation product of poly(ethylene glycol). more...

This paper will describe a new concept for the production of high contrast photopatterns. The method is designed to produce good quality patterns with very low contrast illumination through the use of photobleachable materials in conjunction with standard photoresists. A very thin bleachable layer is first applied to the photoresist surface. Following conventional exposure, the layer is removed and the resist developed in the ordinary way. As a result of the presence of the bleachable material, the contrast of the illumination that reaches the photoresist is increased. It is for this reason that the technique is called contrast enhancement. The degree to which the contrast is enhanced depends on both the photochemical properties of the bleachable material and the dose required to expose the underlying resist. The paper will discuss properties required of the bleachable material in order to make the technique feasible, such as the magnitudes of the extinction coefficient and the quantum yield. Bleaching experiments on candidate materials for the characterization of these parameters will be described. Also to be discussed is a model of the bleaching dynamics, which was used to calculate the improvements in contrast that are achieved as a function of base resist sensitivity. The extra processing steps required by the presence of the bleachable layer will be covered. Submicron resist patterns that demonstrate the resulting improvement in contrast will also be shown. more...

The paper outlines the use of ALGOL 68R in the production of a series of simulation models for a Multi Radar Tracking feasibility study. Particular reference is made to the use of structures , the chaining mechanisms used and the modularity of the models. The multi-radar tracking models were developed in ALGOL 68'R by Plessey Radar Ltd. and run on their 1906S under George 3/MOP. more...

Reduction de plusieurs especes de Ni(III) et d'un complexe de Ni(IV)-oxime. Caractere sphere externe de ces reactions

The reactions of the outer-sphere electron transfer reagent, Ni(9-aneN3)23+, (bis(1,4,7-triazacyclononane)nickel(III) ion) with ascorbic acid, hydroquinone, catechol, and resorcinol have been investigated. The absence of any proton related equilibria with the oxidant provides a means of ascribing the observed inverse hydrogen ion dependences to reactions of the dissociated ascorbate or quinolate ions, (HA−). The data are consistent with the rate-determining one-electron transfer reactions:[Formula: see text]followed by rapid oxidation of the radical ions formed. In the reaction with ascorbic acid, k1 ~ 0 and k2 (T = 25° C) = 5.2 × 106 M−1 s−1 (ΔH≠ = 10.1 ± 2.5 kcal mol−1, ΔS≠ = 5.7 ± 5.1 cal mol−1 K−1). For hydroquinone, catechol, and resorcinol, k1 = 2.9 × 103, 2.8 × 102, and ~0 M−1 s−1and k2 = 6.9 × 109, 4.1 × 109, and 2.8 × 108 M−1 s−1, respectively. These data have been combined with those from other similar reactions leading, by use of a Marcus correlation, to self-exchange rate constants for the HAsc−/HAsc• couple of 3.5 × 105 M−1 s−1 and for the H2Quin0/+ and H2cat0/+ systems of 5 × 107 and 2 × 107 M−1 s−1, respectively. The importance of the effect of bond-reorganisation on electron transfer is discussed. more...

The following carbonyl compounds undergo one-electron reduction by the radicals ·CO2H, ·CO2–, or ·CMe2·NH2 to give species which have been characterised by their e.s.r. spectra; acetaldehyde, propionaldehyde, acetone, glyoxal, biacetyl, pyruvaldehyde, ethyl pyruvate, pyruvic acid, furmaric acid, maleic acid, and diethyl maleate. The dependence of the spectra on pH reveals the occurrence of acid-base equilibria for some of the radicals, and there is also evidence that some of the radicals undergo interconversion between tautomeric forms; the behaviour of fumaric and maleic acid, and the differences between the two compounds, are particularly notable in these respects. more...

Cretaceous bituminous coals of known rank R0 max, vitrinite reflectance) have been examined by ESR (electron spin resonance) and ENDOR (electron nuclear double resonance) techniques. Both highly oxidised (outcrop) and unoxidised mine‐run Balmer coal from the Crowsnest field have been subjected to heat treatment (200‐900°C), and the matrix proton ENDOR signal studied as a function of applied microwave and rf power. Changes in ENDOR line shape and intensity are described with particular emphasis on the presoftening region of the unoxidised coal. A comparative study of the carbonization of hvb and 1vb coking coal from the Crowsnest is reported. more...

Reduction de plusieurs especes de Ni(III) et d'un complexe de Ni(IV)-oxime. Caractere sphere externe de ces reactions

Contrast-enhanced lithography (CEL) is a high-resolution, photolithographic technique which utilizes photobleachable materials in conjunction with conventional resist. The basic CEL concept, material requirements and applications to 10:1 lithography have been described previously. 1,2,3 In this paper we describe the application of this process to 1:1 projection lithography. A comparison of the defect density and linewidth control achieved with both conventional positive resist and CEL is made. These data are collected using electrical measurements on test structures fabricated with a Perkin-Elmer 321. The use of bleachable materials with conventional photoresists results in an increase in required exposure time for any given set of exposure conditions. An experimental analysis of the exposure time penalty vs. the line profile benefit will be presented. Another interesting application for CEL is maskmaking. With continued interest in 1:1 lithography, improved resolution in maskmaking is needed. While this application has not been investigated extensively, preliminary experiments suggest that significant improvements in resolution can be achieved when CEL is employed instead of the standard resist process. Experiments carried out using an Electromask 10:1 maskmaker will be presented. more...

N-Acetyl-p-benzoquinone imine, a hepatic metabolite of acetaminophen, and its analogue, N-acetyl-3,5-dimethyl-p-benzoquinone imine, were metabolized by rat liver microsomes and NADPH to their corresponding 4-aminophenoxyl free radicals. ESR spectra were recorded and unambiguously identified. As indicated by the purple color and confirmed by UV and mass spectroscopy, indophenols were formed as final products. The 4-aminophenoxyl free radical formation could be suppressed by the deacetylase inhibitors, sodium fluoride and paraoxon. Microsomal incubations of N-acetyl-2,6-dimethyl-p-benzoquinone imine and NADPH do not result in a detectable radical concentration; in addition, no indophenol was found. Substitution of NADPH-cytochrome P-450 reductase for rat liver microsomes eliminates the deacetylase activity and results in direct reduction of N-acetyl-3,5-dimethyl-p-benzoquinone imine to the N-acetyl-2,6-dimethyl-4-aminophenoxyl free radical. Neither the incubation of N-acetyl-p-benzoquinone imine nor that of N-acetyl-2,6-dimethyl-p-benzoquinone imine with NADPH-cytochrome P-450 reductase yielded a detectable concentration of the corresponding phenoxyl free radical. When starting material that had been exposed to the atmosphere was used, a previously reported free radical with a splitting constant of approximately 2 G was formed. This spectrum is identical with that of the 2,6-dimethyl-p-benzosemiquinone free radical, implying hydrolysis of the starting material. Neither the N-acetyl-4-aminophenoxyl nor the N-acetyl-2,6-dimethyl-4-aminophenoxyl radical reduces oxygen to form superoxide or react with oxygen in any other detectable way. more...

The authors report a modification of Morov and Pickering's excellent example in which they use column chromatography on Silica Gel to separate the components of the oils.

A new single layer photolithographic liftoff process is described. Coating a thin layer of poly(vinylalcohol) on AZ 5200 series resists produces a surface inhibition effect which results in reentrant profiles. In combination with a contrast enhancing layer such a CEM‐388, high resolution liftoff masks are obtained with excellent process latitude. The application of this new liftoff technique in 0.8‐μm design rule processing is described. more...

The new "solid state" air fresheners provide the basis of an interesting sublimation experiment for the first assignment of a non-majors laboratory entitled "Physical Constants."

E.s.r. spectra are reported for the radicals obtained by the oxidation of a variety of organic compounds by the titanium(III)–persulphate redox system. Evidence is obtained that the sulphate radical anion is formed throughout the pH range employed (1–10·5) and that it can react with organic compounds in at least three ways: by abstracting a hydrogen atom from saturated carbon, by adding to unsaturated or aromatic carbon, and by removing one electron from carboxylate anions and from certain neutral molecules. It displays a marked degree of selectivity in its addition reactions and it behaves differently from the hydroxyl radical in several respects. more...

The reactions of some enols and enol ethers with the hydroxyl and the amino-radical have been investigated by e.s.r. spectroscopy. Adducts from enols with the hydroxyl radical, but not apparently the amino-radical, undergo acid-catalysed elimination of water. Evidence is adduced that the two adducts from an enol ether with the hydroxyl radical, but again not the amino-radical, undergo acid-catalysed interconversion, presumably by way of an oxonium ion; results from the oxidation of 2-methoxyethanol and 1,2-dimethoxyethane with the hydroxyl radical are helpful in elucidating the significance of this rearrangement. A further inference from the results is that the radical MeO·CH(OH)·CH2· is thermodynamically more stable than its alkoxy-conjugated isomer ·CH(OMe)·CH2OH, at least in aqueous acid, and the basis for this is discussed. more...

Earlier studies by e.s.r. spectroscopy of the radicals formed by the interaction of titanium(III) ions and hydrogen peroxide, in the presence or absence of organic compounds, have been extended to the examination of the reactions of the initially formed radicals. Particular use has been made of flow cells which allow one or more reactants to be added shortly after the others have been mixed and before the solution reaches the spectrometer cavity. The results are consistent with the view that the free hydroxyl radical is the primary oxidising agent but that the one-electron oxidation of the resulting organic radicals by both metal ions and hydrogen peroxide is important in determining the relative concentrations of the various radicals which are observed; in this respect, hydrogen peroxide is of special interest because its reduction by organic radicals leads to the formation of further hydroxyl radicals and thence the perpetuation of a chain reaction. This observation has led to the rationalisation both of the dependence of the observed concentrations of readily oxidised radicals on the concentrations of the redox reactants, and of the increase in concentration of the relatively stable radicals derived from titanium(IV)–peroxide complexes which is effected by the addition of small amounts of certain organic compounds. Evidence is also adduced that the markedly different relative concentrations of radicals which are observed when iron(II) ion is used in place of titanium(III) ion are not the result of there being different types of oxidising radicals in the two systems but reflect the fact that iron(III) ion is both a much stronger oxidising agent than titanium(IV) ion for organic radicals and shows a significant degree of selectivity in this capacity between tervalent carbon atoms in different environments. more...