Surface effects on the Formation of Hydrogen Peroxide from dissociated water vapour

The formation of hydrogen peroxide at 77°K from water vapour dissociated in a low-pressure electrodeless discharge was investigated as function of the surface-to-volume ratio. S/V, of both coated and uncoated tubular reactors interposed between the discharge exit and the coolant level. As S/V was increased, the peroxide yield increased to a maximum value and then decreased; this maximum shifted to much lower values of S/V for KCl-coated and H₃PO₄-coated surfaces. Compared with uncoated Pyrex surfaces, H₃PO₄-coatings gave higher H₂0₂ yields whereas KCl-coatings gave lower yields. Surfaces coated well with ice did not show much effect, but condensed water films decreased the H₂O₂ yield. Similar results were obtained when the surface area and the volume traversed by the dissociated vapour were varied at constant S/V. These surface effects are discussed to show that the formation of H₂O₂ occurs via the cold surface reactions H + O₂ → O_aH and H + 0₂H → H₂O₂ and not by the dimerization of OH radicals.     

Some asymptotic results in hydrodynamic lubrication theory

Exact and asymptotic solutions to Reynolds equation for one-dimensional hydrodynamic lubrication are obtained for the case of rigid bearing surfaces and pressure-dependent viscosity.     

A note on general core-valence orthogonality

A method of generating a set of basis functions, which satisfy the condition of strong orthogonality, is developed.     

An evaluation of a sales training programme in a retailing environment

The effectiveness of a proposed sales training programme by a major High Street retailer is assessed using an experimental design which matches test and control stores and measures performance before and after training. The paper also discusses the significance of such programmes in today's shopping environment and the potential of experimentation in retailing.     

Impulse duration: A new instrument for its measurement

An instrument is described which, when used with a ‘peak hold’ reading sound level meter, will measure the durations of acoustic impulses in accordance with the Atherley and Martin and CHABA criteria for hearing damage risk to impulsive noise. The instrument is small, lightweight, can be battery powered and is designed for field use.Comparison tests show that the impulse duration meter gives more accurate and repeatable results than the oscilloscope trace photograph method or the digital waveform recorder method of impulse duration assessment.By using the instrument with a suitable impulse source reverberation time, measurements may be conducted.     

General approach for the synthesis of sarpagine/ajmaline indole alkaloids. Stereospecific total synthesis of the sarpagine alkaloid (+)-vellosimine

[reaction: see text] (+)-Vellosimine has been synthesized enantiospecifically in 27% overall yield from commercially available D-(+)-tryptophan methyl ester via the asymmetric Pictet-Spengler reaction and a stereocontrolled intramolecular palladium-coupling reaction as key steps.     

Utility of the tandem Pauson-Khand reaction in the construction of tetracycles

The scope of the tandem Pauson-Khand reaction has been explored for the regiospecific construction of [5.5.5.5]- and [5.6.6.5]tetracyclic systems via the photolytic method of Livinghouse. The rapid regiospecific entry into the two dicyclopentapentanoid systems 17 and 29 was accomplished from the key diene-diynes 11 and 19b. A photochemically mediated catalytic tandem Pauson-Khand cyclization was employed to prepare the parent ring systems of dicyclopenta[a,e]pentalene (from 19b) and dicyclopenta[a,f]pentalene (from 11) in regiospecific fashion in a one-pot process. Under these conditions, conversion of acyclic diene-diyne 16 into tetracyclic system 17 was achieved in 74% yield, while a similar process was employed to convert 28 into tetracycle 29 in 90% yield. This is much improved over the previous conditions that employed NMO. Six carbon-carbon bonds were generated in this process constituting up to 98% yield for each carbon-carbon bond so formed. Furthermore, tetracyclic [5.6.6.5] systems such as dicyclopenta[b,g]decalins 37, 38, and 40 were prepared from similar diene-diyne precursors via the tandem Pauson-Khand cyclization. Importantly, acetal 36 provided the desired cis-fused [5.6.6.5] system 38a (via 40a/b) in stereospecific fashion. This reaction is unique in that it provides a cis-decalin ring system; moreover, the yield of each of the six carbon-carbon bonds formed in this process was at least 89%. The structure of cis diol 38a was confirmed by X-ray crystallography.     

Linking ArcView™ and XGobi: Insight behind the Front End

Abstract

This article presents aspects of the implementation of a bidirectional link between the Geographic Information System (GIS) ArcView? and the interactive dynamic statistical graphics program XGobi. We describe the main functionality of the link, the underlying remote procedure call (RPC) mechanism, and internal data structures, and discuss topics such as security, concurrency, and linked brushing. We think that these topics are of particular interest to software authors intending to link similar software packages, and software users learning about strengths (and weaknesses) of the implementation of our link.