Use of flavour profile and consumer panels to determine differences between local water supplies and desalinated seawater.

The San Diego County Water Authority of California has initiated planning for coastal desalination facilities to augment their water supplies. Integration of the different water qualities from these facilities into existing pipelines must be achieved. This investigation determined whether, and to what degree, consumers can discriminate between desalinated seawater and imported water supplies and how these investigations can contribute to decision making regarding the need for construction of facilities to blend such supplies prior to delivery. Based upon the results of the flavour profile analysis panel and the consumer evaluation sessions, it was concluded that free chlorine versus chloramine disinfection or different concentrations of disinfectants did not significantly affect consumer perception of the taste and odour of desalinated seawater or blends with Colorado River water and State project water. Consumers were able to discern between desalinated seawater and imported water, preferring imported water when forced to make a choice. However, the investigators did not believe that the difference in consumer perception was significant enough to warrant special blending facilities to mitigate the relatively minor aesthetic quality differences between imported water supplies and desalinated seawater.     

Development of an empirical mathematical model for describing and optimizing the hygiene potential of a thermophilic anaerobic bioreactor treating faeces.

Poor sanitation and insufficient disposal of sewage and faeces are primarily responsible for water associated health problems in developing countries. Domestic sewage and faeces are prevalently discharged into surface waters which are used by the inhabitants as a source for drinking water. This paper presents a decentralized anaerobic process technique for handling of such domestic organic waste. Such an efficient and compact system for treating faeces and food waste may be of great benefit for developing countries. Besides a stable biogas production for energy generation, the reduction of bacterial pathogens is of particular importance. In our research we investigated the removal capacity of the reactor concerning pathogens, which has been operated under thermophilic conditions. Faecal coliforms and intestinal enterococci have been detected as indicator organisms for bacterial pathogens. By the multiple regression analysis technique an empirical mathematical model has been developed. The model shows a high correlation between removal efficiency and both, hydraulic retention time (HRT) and temperature. By this model an optimized HRT for defined bacterial pathogens effluent standards can be easily calculated. Thus, hygiene potential can be evaluated along with economic aspects. In this paper not only results for describing the hygiene potential of a thermophilic anaerobic bioreactor are presented, but also an exemplary method to draw the right conclusions out of biological tests with the aid of mathematical tools.     

Developments in high-resolution positron emission tomography at MGH

The development of high resolution PET systems is important for the wider application of this techniques. The resolution of PET is limited by a number of physical factors such as positron range, small angle deviation, and sampling frequency. The design of the detector array and its sensitivity remain critical factors; designs incorporating analog coding have proven to be useful. PCR-I, a single plane PET system, has demonstrated the concept and has produced useful images in animal studies. PCR-II will extend the concept to a two dimensional detector array resulting in a system with high resolution and high sensitivity.     

Mixed-mode fracture of composites using Iosipescu shear test

Finite element analysis is used to determine the influence of elastic properties on the stress distribution in the Iosipescu shear test specimen. Two different boundary conditions are used which assume either the application of force couples or specified displacements. The effect of orthotropy ratio is investigated with E ₁₁/E ₂₂ranging from 1 to 14.2. The analysis is extended to partially cracked specimens and used to calculate the basic fracture parameters in aligned composite materials. In particular, the failure of specimens with two axial splits, nucleated at the roots of the notches, and extended in the fibre direction is analysed. It is shown that the stress distribution is strongly dependent on both the elastic properties and boundary conditions. The mixed mode stress intensity factors K _Iand K _IIat the crack tips tend to increase with orthotropy ratio. The analysis is discussed with respect to the limited experimental data available for this test geometry. From the numerical and experimental results the mixed mode toughness is estimated in terms of the critical stress intensity factors and the critical energy release rate.Résumé On recourt à une analyse par éléments finis pour déterminer l'influence des propriétés élastiques du matériau sur la distribution des contraintes dans l'éprouvette de l'essai de cisaillement de Iosipescu. Deux conditions aux limites sont considérées: l'application de couples de forces ou de déplacements imposés. L'effet du rapport d'orthotropie est étudié, pour des valeurs de E ₁₁/E ₂₂comprises entre 1 et 14,2. L'analyse est étendue au cas d'éprouvettes partiellement fissurées, et est utilisée pour le calcul des paramètres fondamentaux de rupture dans des matériaux composites à fibres alignées. On analyse en particulier la rupture d'éprouvette comportant deux séparations axiales, prenant naissance aux racines ds entailles et s'étendant dans la direction de la fibrosité.On montre que la distribution des containtes dépend fortement des propriétés élastiques du matériaux et des conditions aux limites. Les facteurs d'intensité de contrainte correspondant au mode mixte K _Iet K _IIde rupture aux extrémités de la fissure tendant à croître avec le rapport d'orthotropie.Une discussion sur cette analyse tient compte du nombre limité de données expérimentales disponibles pour cette géométrie d'éprouvettes. On peut estimer la ténacité sous mode mixte à partir des résultats numériques et expérimentaux, et l'exprimer par les facteurs critiques d'intensité de contraintes et la vitesse critique de relaxation de l'énergie.     

Implementation of sustainable sanitation in existing urban areas: long-term strategies for an optimised solution.

If technologies for decentralised sanitation and reuse (DESAR) and for natural stormwater management should at least partially replace existing systems, then intensive reconstruction work becomes essential. A conversion can only be realised successively over a long period due to high construction and financial expenses and requires new strategies. This paper presents the development and practical implementation of a mathematical tool to find an optimised strategy for the realisation of alternative and more decentralised drainage and sanitation concepts in existing urban areas. The succession of construction measures (e.g. the implementation of decentralised greywater recycling) for the whole period of consideration is determined based upon a mathematical optimisation model on the condition that the favoured future state is known. The model describes the complex interdependencies of the urban water and nutrient cycle and enables the minimisation of both financial efforts and ecological impacts on the way toward the future state. The results of the implementation for a rural area in Germany show that the mathematical optimisation is an adequate instrument to support decision-making processes in finding strategies for the realisation of sustainable urban water management.     

Investigation of the V(V)/V(IV) system for use in the positive half-cell of a redox battery

The V(V)/V(IV) redox couple system has been studied at glassy carbon and gold electrodes in sulphuric acid solutions, using both cyclic voltammetry and     

A REVIEW OF TEXTURAL DEFECTS IN COOKED RECONSTITUTED LEGUMES —THE INFLUENCE OF STRUCTURE AND COMPOSITION

Legumes provide an important part of the world's protein requirements, as well as other nutrients, but they are underutilized as food. A major factor limiting expanded consumption is storage induced textural defects that prolong cooking time and demand correspondingly higher energy requirements for preparation. These defects, including the hard-to-cook phenomenon and hardshell, are initiated by structural and compositional factors but can be at least partially controlled by storage and processing conditions. Structural components implicated include seed coat, cell walls, middle lamella, starch granules and membranes while, compositionally, proteins, carbohydrates, phytate, polyphenols and lignin may also be important. Methods of texture measurement of legumes, including mechanical, physical and sensory properties are reviewed. The most commonly held hypothesis for the mechanism of the hard-to-cook defect states that beans fail to soften after exposure to high temperature and humidity storage because the increased water activity potentiates phytase which hydrolyzes phytate, rendering it no longer capable of chelating the Ca⁺⁺ and Mg⁺⁺ ions of the middle lamella and, hence, undissoluble. More recent evidence, however, provides potential roles for lignification, starch gelatinization and perhaps other mechanisms depending upon conditions. The possibility of a nonenzymatic as well as an enzymatic route is raised and thoughts presented on a course of action for future research.