Improvement in hydrolytic procedure for GLC determination of non-indolyl glucosinolates in rapeseed as isothiocyanates

Some methods determine the non-indolyl glucosinolates content in rapeseed as their hydrolysates: the isothiocyanates and the oxazolidinethiones. These methods in their present form underestimate the amount of the glucosinolates content. In this investigation, a modified method was developed to give a better quantitative estimate, indicating a glucosinolate level five times that obtained by a typical existing method.     

Modification of platinum surfaces by spontaneous deposition: Methanol oxidation electrocatalysis

The presence of a second metal on platinum surfaces affects the performance of methanol oxidation. However, most of the electrocatalytic reactions are studied by using electrochemically deposited platinum alloys, but in the case of spontaneous deposition the situation is not so clear since the surface distribution, stability and morphology are usually not well documented. The formation of surface decorated samples on mono- and poly-crystalline platinum is followed by electrochemical and spectroscopic techniques and analysis of their performance towards methanol adsorption and oxidation compared with that on pure platinum. Pt/Sn and Pt/Ru are of special interest because of their well-known performance in methanol fuel cells. Methanol oxidation on Pt(111)/Ru, Pt(111)/Sn and Pt(111) shows that ruthenium is the only one able to promote the reaction since the simultaneous dissolution of tin occurs and competes with the process of interest. The in situ infrared spectroscopy is used to compare methanol oxidation on Pt(111)/Ru and Pt(111) in acid media using p-polarized light. The formation of bridge bound carbon monoxide is inhibited in the presence of ruthenium ad-species, whereas on Pt(111) the three adsorption configurations are observed. Linear sweep polarization curves and Tafel slopes (calculated from steady state potentiostatic plots) for methanol oxidation are compared on polycrystalline surfaces modified by tin or ruthenium at different coverages. There is almost no change in the Tafel slopes due to the presence of the foreign metal except for Pt/Ru, where a 0.09 V decade⁻¹ slope was calculated below 0.55 V due to hydroxyl adsorbates on ruthenium islands. The anodic stripping of methanol residues on the three surfaces indicates a lower amount of carbon monoxide-type adsorbates on Pt/Ru, and the simultaneous tin dissolution process leading to residues oxidation on Pt/Sn electrodes.     

Adaptive user modelling in intelligent telephone and email assistants

With the burgeoning complexity and capabilities of modern information appliances and services, user modelling is becoming an increasingly important research area. Simple user profiles already personalise many software products and consumer goods such as digital TV recorders and mobile phones. A user model should be easy to initialise, and it must adapt in the light of interaction with the user. In many cases, a large amount of training data is needed to generate a user model, and adaptation is equivalent to retraining the system. This paper briefly outlines the user modelling problem and work done at BTexact on an intelligent personal assistant (IPA) which incorporates a user profile. We go on to describe FILUM, a more flexible method of user modelling, and show its application to the telephone assistant and email assistant components of the IPA, with tests to illustrate its usefulness.     

A micromechanical model for cleavage-crack reinitiation

A crack-tip screening analysis of cleavage fracture of steel is developed. The analysis incorporates evidence that reinitiation of an arrested cleavage crack requires less stress intensity than cleavage initiation from a fatigue precrack. Fractographic evidence as well as metallographic sectioning of arrested cracks have previously shown that the mechanism of rapid crack propagation by cleavage is affected strongly by partial crack-plane deflection which leaves unbroken ligaments in its wake. The tearing of these ligaments by dimple rupture is the dominant energy-absorbing mechanism. Earlier etch-pit experiments using an Fe-Si alloy showed that the crack-tip stress intensity based on plastic zone size is extremely low. These observations are incorporated into a model in which cleavage crack reinitiation is analyzed using a sharp crack that is shielded by a distribution of pinching forces along its faces. During reloading of the arrested crack, the ligaments restrict crack-tip blunting, leading to higher local stresses. As a result, lower stress intensities are needed for reinitiation than for initiation from a fatigue precrack.     

The function of bleaching earths in the processing of palm,palm kernel and coconut oils

The results presented in the literature, which attempt to elucidate the mechanisms by which triglyceride oils are bleached by earths, are reviewed. The impact of this work and how the mechanistic proposals affect changes in oil properties are considered, with particular emphasis on the needs of the palm oil processor. Important properties include color, metals and phosphorus content and oxidative stability of the oil. Investigations made in our own laboratories have been aimed at elucidating the effect of varying physical and chemical properties of the bleaching earth on the quality of bleached and deodorized oils. Techniques used in this work are pore-size distribution, surface area, scanning and transmission electron microscopy and a variety of chemical and X-ray analysis methods. The ability to vary such parameters in montmorillonite clays by alteration of process conditions to give materials with specific performance characteristics is demonstrated. Comparisons are made between acid-activated montmorillonites and other clay types.     

Effective VLSI processor architectures for HLL computers: the RISCapproach

The design principles of reduced-instruction-set computer (RISC) architectures as they apply to VLSI implementation for high-level languages (HLLs) are presented. The nature of general-purpose HLL computations is discussed in terms of static and dynamic program measurements, and the HLL features that need efficient support are identified. CISC (complex-instruction-set computer) and RISC approaches to general-purpose HLL computers are outlined, the effects of instruction-set reduction on both code size and execution time are evaluated, and the delayed-jump concept is introduced. The Berkeley RISC architecture is presented as an example     

Optical networks for local loop applications

Some of the options for optical technology within the local loop environment are examined. In particular, passive shared access networks have been considered in some detail. These networks show great promise for delivering existing telephone services to small to medium business customers (4-30 lines) economically by the early 1990s. Extending fiber to the home will also be possible by virtue of a similar passive network infrastructure for customers requiring new broadband services beyond the single telephone line. For one-line plain old telephone service (POTS) customers, an intermediate approach of terminating the fiber network at the final network distribution point, with copper retained for the final leg, may be used prior to the provision of broadband services. A key feature of the passive optical network architecture is the use of wavelength-division multiplexing (WDM) as an upgrade strategy, allowing graceful upgrading from telephone services to multichannel high-definition television (HDTV) on gigabit/second bearers and full two-way switched broadband services employing wavelength routing across the network