Purification and biochemical characterisation of a novel glutamate decarboxylase from rice bran

BACKGROUND: Glutamate decarboxylase (GAD) is a useful enzyme whose main function is to catalyse the irreversible α‐decarboxylation of L ‐glutamate to produce γ‐aminobutyric acid. The cheap and abundant rice‐processing by‐product rice bran contains a high amount of GAD, the purification and characterisation of which have not yet been reported. In this study, research on rice bran GAD was initiated. RESULTS: Rice bran GAD was purified to homogeneity via a combined purification protocol of ammonium sulfate fractionation, ion exchange chromatography and two gel filtrations, with a purification fold of 128.6 and an activity recovery of 21.3%. The enzyme was active at pH 5.5 and 40 °C and retained 80% of its original activity in the pH range 5–9 and the temperature range 30–50 °C. GAD activity was significantly enhanced in the presence of Ca²⁺ but strongly inhibited by Ag⁺, Hg²⁺, sodium dodecyl sulfate and CH₃COOH. Kinetic determination of the apparent K_m for L ‐glutamate and pyridoxal 5′‐phosphate gave values of 27.4 mmol L^?1 and 1.16 µmol L^?1 respectively. CONCLUSION: Considering that rice bran is cheap and commercially available and that rice bran GAD is relatively stable, the development of cost‐effective rice bran GAD‐related functional foods would seem to be feasible. Copyright © 2010 Society of Chemical Industry     

An investigation on oxidation/carburisation of 9Cr-1Mo steel heat exchanger tube in an AGR environment

Abstract

9Cr–1Mo steels have been used extensively in the power generation industry. In this study, a wide range of experimental samples exposed at different times and temperatures in a CO₂ environment were analysed to look at the development of the metal and oxides over time. The main objective of this work was to obtain a better understanding of the carburisation and oxidation behaviour of 9Cr 1Mo steels as a function of temperature/time, with special attention paid to the transition from protective to breakaway oxidation. In addition, experiments were also carried out to investigate any links between oxidation transition and carburisation behaviour of these materials.     

Review of methodologies for composite material modelling incorporating failure

Advanced composite materials are finding increasing application in aerospace, marine and many other industries due to the advantages in performance, structural efficiency and cost they provide. However, despite years of extensive research around the world, a complete and validated methodology for predicting the behaviour of composite structures including the effects of damage has not yet been fully achieved. The Cooperative Research Centre for Advanced Composite Structures (CRC-ACS) is leading a currently running collaborative project to develop a methodology for determining mechanical behaviour and failure in composite structures. Key drivers of the project are the use of multi-axial testing machines for material characterisation and an appreciation of the issues involved due to the different length scales of any analysis. As part of the project, a critical review was performed to assess the state of the art in material constitutive modelling and composite failure theories. This paper summarises the results of the review, which includes a discussion of the various theories and approaches within the context of the dissipated energy density framework. The results of the review will be applied within the project to select appropriate constitutive modelling and failure approaches for implementation within a data-driven material characterisation methodology.     

Some aspects of characterisation,utilisation and environmental effects of fly ash

A review on fly ash, an important but problematic waste material is presented. The article deals with several aspects of the characterisation, extraction of metal values leaching and associated environmental pollution problems due to fly ash. Characterisation includes classification, physicochemical and mineralogical analysis, presence of organic carbon and the significance of cenospheres. Utilisation aspects are confined to extraction of metal values and discuss the elemental distribution in fly ash while also covering several aspects of leaching including the leaching of specific metals. Effect of fly ash on surroundings, including ground water pollution and associated problems during disposal, are considered while dealing with the environmental aspects. Some remedial measures are also suggested. © 2001 Society of Chemical Industry     

Textile injection process characterisation by means of a spiral mould

New developments are being carried out within the injection moulding field, such as gas injection, bi-injection, co-injection, sequential injection, compression injection or textile injection processes. These techniques require new developments as they highly modify design and process conditions. In this work, the influence over the plastic material flow of the introduction of different film textiles into the mould is measured. A specific measurement system consisting of a monitorised spiral mould with pressure sensors has been used to measure the influence of different tissues over the mould pressures. As an application of this measurement system, a viscous model is generated to characterise the rheological behaviour of the thermoplastic and textile joint. The viscous model obtained is applied on a conventional CAE tool for the simulation of textile injection pressure results for the different film textiles analysed.     

A process mineralogy approach to geometallurgical model refinement for the Namakwa Sands heavy minerals operations,west coast of South Africa

The original geometallurgical model for the Namakwa Sands deposit was modified to accommodate ore blends in addition to the various single ore types. A process mineralogy approach was followed in a structured and systematic manner to evaluate the integrity of the adjusted model, particularly for ilmenite and zircon, the minerals of highest intrinsic value. This study reproduced recovery relationships predicted by the geometallurgical model for each of the key process functions, and as a result the integrity of the geometallurgical model is validated. Overall, the recovery potential determined for ilmenite and zircon are well adjusted to model estimates. Poor mineral liberation, an anomalously high abundance of garnet and pyroxene and variation in particle chemistry are recognized as the key recovery penalties. The gangue content is the most significant constraint to ilmenite recovery, whereas zircon chemistry is the most important negative factor in the production of a premium quality zircon product. Results of this study contributed to the refinement of the current geometallurgical model and also identified opportunities to optimise mineral resource utilisation in the future.     

Freeform texture representation and characterisation based on triangular mesh projection techniques

Texture characterisation for freeform non-Euclidean surfaces is becoming increasingly important due to the widespread of the use of such surfaces in different applications, e.g. the additive manufacturing. Four main steps are required to analyse and characterise those surfaces which include new surface representation, surface filtration and decomposition, texture representation methods and finally the calculation of the surface parameters. Recently, the representation, as well as the filtration and decomposition, of freeform surfaces have been investigated and some algorithms have been proposed. This paper, however, shed the light on how to represent the texture of freeform non-Euclidean surfaces before calculating the parameters. A novel model for freeform surface parameterisation is introduced; this new model proposes the use of a projection algorithm before the actual calculation of the parameters. Different projection algorithms have been adopted from the mesh projection techniques found in the field of computer graphics. The results of applying those algorithms to represent the texture of both simulated and bio-engineering surfaces are shown, also a comparison between those algorithms has been carried out. Furthermore, examples of calculating some of the surface parameters for freeform surfaces are given.     

Influence of surface pre-treatments on disturbed rolled-in subsurface layers of aluminium alloys

Rolling is known to alter the surface properties of aluminium alloys and to introduce disturbed subsurface layers. These layers are characterised by a refined grain structure, rolled-in oxide particles, a fine distribution of intermetallic particles, various voids and cracks.In this study, the effects of some surface pre-treatments, i.e., alkaline etching at various temperatures and chemical cleaning with Nabuclean and CrO₃/H₃PO₄, on these rolled-in layers are investigated by means of surface analytical techniques. The changes in composition and morphology of the (sub)surface are studied with scanning electron microscopy/energy dispersive X-ray analysis and backscattered electron imaging (SEM/EDX + BEI). The presence of incorporated oxide particles is evaluated by measuring the total reflectance. The (re-)distribution of alloying, impurity and trace elements upon these surface treatments is investigated with radiofrequency glow discharge optical emission spectrometry (rf-GDOES).     

Composite hydrogeological investigation and characterisation methods applied at a nuclear power plant site in Taiwan

Drawing from the lessons learnt from the Fukushima nuclear disaster in Japan, the assessment of subsurface environmental hazard around nuclear power plants has emerged as a critical task. Consequently, aiming to better understand the possible environmental impact of radiation leaks into the groundwater, a prescreening programme was initiated in 2011 by the Taiwanese government. As part of this programme, this study conducted various borehole prospecting techniques to identify in situ hydrogeological characteristics at Chin‐Shan Nuclear Power Plant. Borehole electrical log, sonic log and temperature/conductivity log were conducted to explain the regional lithologic conditions and permeability of the formation. In conjunction with this, the interwell tracer and pumping test was carried out to simultaneously determine the hydraulic parameters. In our opinion, the implementation of such in situ end‐to‐end investigations is essential in interpreting in situ fluid and solute transport dynamics prior to programming any numerical scheme for early warning, vulnerability assessment and regular monitoring of a nuclear power plant site.