938 research outputs found
Sort by
Butternut and beetroot pectins: Characterization and functional properties
No full textThe physicochemical characteristics and functional properties of butternut (Cucumis moschata Duch. ex Poiret) and beetroot (Beta vulgaris L. var. conditiva) pectins obtained by enzymatic extraction from by-products of vegetable processing have been evaluated. The molecular mass distribution was determined using Gel Permeation Chromatography using light scattering, refractive index and UV detectors and the samples were found to be highly heterogeneous and polydisperse. Mw values of 136,000 and 1,309,000 g/mol were determined for butternut and beetroot pectins respectively. Butternut pectin had a high degree of methyl esterification. In the presence of high concentrations of sugar and at low pH, this pectin did not form gels but instead produced viscous solutions. Solutions showed pseudoplastic flow behaviour with a shear thinning index of 0.68 as determined from the Power law model. Beetroot pectin had a low degree of methyl esterification and formed gels with addition of Ca2+ at concentrations of 10 mg/g pectin or higher. The maximum value of the storage modulus was obtained at a Ca2+/GalA ratio of 0.25. The thermal stability of gels suggested that hydrogen bond interactions prevailed in the absence of Ca2+, whereas electrostatic junction zones increasingly developed between pectin chains as the calcium concentration increased. Aqueous solutions of butternut and beetroot pectins significantly reduced surface tension and both samples were able to form stable oil-in-water emulsions. It was found that protein and/or polyphenol – rich fractions present in the pectins adsorbed at the oil–water interface and were responsible for the emulsification properties
Synthesis, characterisation and self assembly of biosurfactants based on hydrophobically-modified inulins
Get PDFNovel biosurfactants have been synthesised using a low energy, environmentally friendly process by the derivatisation of inulin with octenyl (OSA) and dodecenyl (DDSA) succinic anhydrides in aqueous solution. The inulin and its derivatives have been characterised using GPC/MALLS, HPAEC-PAD, FTIR and NMR and the reaction efficiency was found to be between 59-95 %. The efficiency was generally higher for OSA derivatives compared to DDSA derivatives. The hydrophobic derivatives were found to aggregate in solution and the critical aggregation concentration (CAC) was determined using dye solubilisation, surface tension, dynamic light scattering and conductivity. There was reasonable agreement in the CAC values obtained by the different techniques except for conductivity. It was found that the CAC decreased with increasing alkenyl chain length and degree of modification and the values were significantly lower for the DDSA derivatives compared to the OSA derivatives. GPC elution profiles for the DDSA-inulin using 12 mole % reagent confirmed the presence of aggregates with a molecular mass of ~2.5 x 106 g/mol and a radius of gyration of ~25 nm corresponding to ~550 inulin molecules. Dynamic light scattering (DLS) study was undertaken to determine the hydrodynamic radius and values obtained for the DDSA (12 %) derivative were 30 nm in both water and 0.1 M sodium nitrate, while for the OSA (12 %) derivative values of 13 nm and 7 nm were obtained. The derivatives have potential application in the stabilisation of particulate dispersions and emulsions and also in the encapsulation and delivery of drugs
A Gaussian Process Surrogate Model Assisted Evolutionary Algorithm for Medium Scale Expensive Black Box Optimization Problems
Get PDFSurrogate model assisted evolutionary algorithms (SAEAs) have recently attracted much attention due to the growing need for computationally expensive optimization in many real-world applications. Most current SAEAs, however, focus on small-scale problems. SAEAs for medium-scale problems (i.e., 20-50 decision variables) have not yet been well studied. In this paper, a Gaussian process surrogate model assisted evolutionary algorithm for medium-scale computationally expensive optimization problems (GPEME) is proposed and investigated. Its major components are a surrogate model-aware search mechanism for expensive optimization problems when a high-quality surrogate model is difficult to build and dimension reduction techniques for tackling the “curse of dimensionality.” A new framework is developed and used in GPEME, which carefully coordinates the surrogate modeling and the evolutionary search, so that the search can focus on a small promising area and is supported by the constructed surrogate model. Sammon mapping is introduced to transform the decision variables from tens of dimensions to a few dimensions, in order to take advantage of Gaussian process surrogate modeling in a low-dimensional space. Empirical studies on benchmark problems with 20, 30, and 50 variables and a real-world power amplifier design automation problem with 17 variables show the high efficiency and effectiveness of GPEME. Compared to three state-of-the-art SAEAs, better or similar solutions can be obtained with 12% to 50% exact function evaluations
Revisiting the conformation of xanthan and the effect of industrially relevant treatments
Get PDFThe structure and conformation of xanthan in aqueous solution following various processing treatments typically encountered in its application were investigated in this study. Treatments such as heating, autoclaving, high pressure homogenisation and irradiation were subjected to the same sample. Parameters such as weight average molecular weight (M-w). polydispersity index, root mean square radius of gyration, intrinsic viscosity and Huggins constant were used to monitor the effect of these treatments. Additionally, we have quantified the mass recovery of samples examined by gel permeation chromatography and light scattering to properly account for all fractions present in xanthan solutions. Atomic force microscopy (AFM) images together with height measurements confirmed that xanthan conformation is double helical ordered renatured state (pre-heat treated by the manufacturer) in dilute solution conditions and random coil conformation in very dilute solution. The ordered (renatured) conformation is shown to have partially molten double helix, with more flexibility than the perfectly ordered native double helix. Heat treatment for 2h at 85 degrees C reduces the M-w of xanthan to half its initial value, and mass recovery measurements indicate that it completely overcomes its associative nature. Thermally treated xanthan solution in the dilute region leads to an order-disorder transition, as determined by contour length per unit mass. Similarly, irradiation of xanthan solution results in an order-disorder transition together with the production of single strand low molecular weight molecules. Autoclaving and high pressure homogenisation treatments cause degradation of xanthan. The results from treated xanthan solutions following high pressure homogenisation and irradiation confirm that xanthan does not reassociate. A revised summary of xanthan conformation in solution together with schematic models following the various treatments are proposed. (C) 2012 Elsevier Ltd. All rights reserved
Damned if you do and damned if you don’t: Language choice in the research interview
Get PDFEuropean language activists have successfully campaigned for the right to use regional or minority languages in a range of social contexts. Despite this, such rights are rarely exercised. Non-use is generally understood as a function of the unavailability and/or inaccessibility of appropriate language services and Governments across the European Union have been criticised as a consequence of this. The article draws on qualitative data to examine the negotiation over language use in a research encounter where the Welsh or the English language might have been used. It is argued that the availability of language choice is only one of a number of factors likely to influence which language is selected for usage in any context. Indeed, language selection is shown to be the outcome of complex and situated negotiation. The findings challenge oversimplified understandings about minority language use and non use
Decision making and decision communications in elite rugby union referees: An inductive investigation
Get PDFThe application of law, combined with contextual judgment and communication have been shown to be essential skills of the elite sports official (Mascarenhas, Collins & Mortimer, 2005). Further, the behaviours that officials demonstrate to communicate decisions to sport participants have important implications for match outcomes and perceptions of fairness (Mellick et al., 2005; Simmons, 2010). The purpose of the present study was to explore the higher - order decision making and decision communication processes of three international rugby union referees. Semi – structured interviews were conducted to explore the routines, psychological strategies and processing skills they utilise to meet the decision making demands of the game. Interview data were analysed by means of thematic content analysis providing four core themes related to expert decision making processes and decision communications: corporate theatre, pre – game preparation and post – game analysis, refereeing philosophy and approach, and within – game psychological skills. The results of this investigation will provide practice – based information to inform training interventions as a pedagogic tool to assist pre – elite sport officials in developing higher – order understandings of decision making processes and communication patterns
Reflections on Student, Service User and Carer Involvement in Social Work Research
Get PDFThis article will reflect on the experience of undertaking a participatory action research influenced study within a module of a social work degree programme. In doing so it will touch on some of the literature associated with student, service user and carer involvement in qualifying programmes, and in particular on research and module design. It will outline the history of service user and carer involvement in respect of a specific module within a singular degree course. It will provide an overview and some findings of the study, which sought to evaluate the involvement of an inherent service user and carer group within that degree course. However, as service user and carer involvement within degree programmes has had significant attention within the wider literature, the current study seeks to present a reflexive commentary on student, service user and carer involvement in research modules and participatory action research. Whilst the research presented here should be regarded as an initial foray with acknowledged limitations, it equally highlights some perspectives that lead to an understanding of how greater levels of student, service user and carer involvement within social work research might be achieved, in particular in the context of social work qualifying programmes
Secure military social networking and rapid sensemaking in domain specific concept systems: research issues and future solutions
Get PDFThis paper identifies the need for a secure military social networking site and the underlying research issues linked to the successful development of such sites. The paper further proposes a solution to the most basic issues by identifying and tackling known potential security threats to military personnel and their families. The paper further defines the base platform for this development to facilitate rapid sensemaking to inform critical communications and rapid decision making processes during abrupt governance and eco-system change, and how the plethora of information (termed as Big Data) on social networking sites can be analysed and harnessed. Underlying architectural issues, efficiency and complexity are explored and their future development is considered
Removal of Mid Spatial-Frequency Features in Mirror Segments
Get PDFBoX grinding technology has been adopted in our E-ELT segment process. The mid-spatial frequency features generated can be removed by several 'smoothing' processes. We have reported here a novel method that can smooth these features whilst avoiding edge down-turn. This process can be scaled up to E-ELT segment fabrication time-scale. It has been experimentally demonstrated that the surface quality is good enough for subsequent Zeeko form correction technology to achieve form specifications
Discourses from youth work practice: the youth worker’s story
Get PDFThis paper reports on a pilot study into youth workers’ stories of practice. Using a qualitative case study approach, data were collected via semi structured interviews with ten youth workers in order to develop a meaningful dialogue about their practice and the realities of their professional role with young people. The diverse group of participants reflected positively on enjoyable and creative aspects of their work, some of the dilemmas they faced and experiences which had made a lasting impression. They characterised their work as being ‘young people centred’, ‘about beginnings and not end products’ and ‘a privilege’