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Development of modifying compounds for multilayer nano-structured coatings for cutting tools
No full textThe subject of this study was to research and develop modified multilayer nanostructured wear-resistant coatings (NWC) for cutting tools. NWC are formed through the innovation process of filtered cathodic vacuum-arc deposition (FCVAD). The processes of FCVAD allow forming NWCs by filtering vapour-ion flow of macro/micro particles in the plasma torch of vacuum arc, using the plasma duct of special structure isolated from the station chamber, when the angle of rotation of the plasma stream is 120°. This work presents the configuration of the system, alongside with the influence of process parameters on the output. The topology of the coatings is presented together with the hardness and a comparison between standard physical vapour deposition (arc PVD) and FCVAD coating technologies. Machining tests were undertaken in turning of standard HB200 steel and heat resistant nickel alloy. The results are presented in terms of tool flank wear. It is shown that the application of the NWC secured 2-6 fold extended tool lif
A conceptual framework for a comprehensive regional strategy : a case study of the eastern region, Kingdom of Saudi Arabia.
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Protein containing porous polymers for biocatalytic applications
No full textOver the last twenty years there has been a great deal of research conducted into the use of enzymes as catalysts for reactions conducted in non-aqueous media. Not only has it been shown that enzymes can function effectively in organic media, but also that the range of reactions that they can catalyse has been vastly increased. The major disadvantages associated with non-aqueous enzymatic catalysis are relatively slow reaction rates compared to traditional aqueous catalysis, poor enzyme stability towards polar organic solvents and protein agglomeration, which leads to reduced efficiency, making recovery and reuse of the enzyme very difficult. Immobilisation of the enzyme on a suitable support material has been shown to be an effective method in overcoming these problems. This study examined several different methods for immobilising a-chymotrypsin on novel support materials. The catalytic activities of the preparations were assayed by following the transesteriflcation reaction between N-acetyl-L-tyrosine ethyl ester (A TEE) and propan-l-ol by high performance liquid chromatography (HPLC). Immobilised enzyme activities were compared to those obtained for simple unsupported lyophilised preparations of a-chymotrypsin. Uniform porous poly(acrylamide) beads were loaded with various quantities of enzyme via an adsorption procedure. Catalytic activity was measured over a wide range of thermodynamic water activities and was found to be similar to the lyophilised preparations. However, the immobilised enzyme was shown to be more resistant to changes in pH and temperature, and could easily be recovered from the reaction mixture and reused. Design of experiment methodology was employed to optimise support matrices constructed from six component materials. The enzyme was immobilised via a noncovalent entrapment method. The best composites prepared displayed a fifty-fold increase in catalytic activity and a three-fold increase in mechanical strength relative to the equivalent a-chymotrypsin controls. These materials could be reused more than ten times whilst still retaining useful catalytic activity. Porous poly(acrylamide) monoliths containing entrapped a-chymotrypsin were synthesised using a novel carbon dioxide high internal phase emulsion templating technique. The effects of enzyme loading, carbon dioxide pressure and monomer to crosslinker ratio were examined. The corresponding enzyme activity of all the emulsion templated materials was shown to be higher than for the unsupported lyophilised preparations, with the best materials exhibiting a ten-fold increase in activity. Multipoint covalent enzyme immobilisation was also studied. The structure of the enzyme was first modified so as to include a polymerisable functionality. This modified enzyme was then dissolved in organic solvents via the formation of ion-pairs with various anionic surfactants. It was shown that the enzyme remained in solution when transferred from organic solvents to a mixture of monomers. The dense gas porogen R134a was then added to the solution of enzyme in monomer, prior to the initiation of a polymerisation reaction. The resulting crosslinked enzyme-containing polymers were shown to possess useful catalytic activit
The Role of Nutraceuticals In The Prevention of Cardiovascular Disease
No full textCardiovascular disease (CVD) ranks among the most common health-related and economic issues worldwide. Dietary factors are important contributors to cardiovascular risk, either directly, or through their effects on other cardiovascular risk factors including hypertension, dyslipidemia and diabetes mellitus. Nutraceuticals are natural nutritional compounds, which have been shown to be efficacious in preventative medicine or in the treatment of disease. Several foods and dietary supplements have been shown to protect against the development of cardiovascular disease. The aim of this review is to present an update on the most recent evidence relating to the use of nutraceuticals in the context of the prevention and treatment of cardiovascular disease
Kinematic Clues to Bar Evolution for Galaxies in the Local Universe: Why the Fastest Rotating Bars are Rotating Most Slowly
No full textWe have used Spitzer images of a sample of 68 barred spiral galaxies in the local universe to make systematic measurements of bar length and bar strength. We combine these with precise determinations of the corotation radii associated with the bars, taken from our previous study, which used the phase change from radial inflow to radial outflow of gas at corotation, based on high-resolution two-dimensional velocity fields in Hα taken with a Fabry-Pérot spectrometer. After presenting the histograms of the derived bar parameters, we study their dependence on the galaxy morphological type and on the total stellar mass of the host galaxy, and then produce a set of parametric plots. These include the bar pattern speed versus bar length, the pattern speed normalized with the characteristic pattern speed of the outer disk versus the bar strength, and the normalized pattern speed versus R, the ratio of corotation radius to bar length. To provide guidelines for our interpretation, we used recently published simulations, including disk and dark matter halo components. Our most striking conclusion is that bars with values of R < 1.4, previously considered dynamically fast rotators, can be among the slowest rotators both in absolute terms and when their pattern speeds are normalized. The simulations confirm that this is because as the bars are braked, they can grow longer more quickly than the outward drift of the corotation radius. We conclude that dark matter halos have indeed slowed down the rotation of bars on Gyr timescales. © 2017. The American Astronomical Society. All rights reserved.
Decision-Making: understanding undergraduate fitness to practise panels using a simulated case study approach
Full text linkFitness to Practise (FtP) is an emerging area of interest within the health and social care field due to the increasing high profile cases relating to professionalism and conduct of practitioners. Research has ‘yet to catch up’ with the emerging interest and the current body of evidence predominately consists of literature reviews and descriptive or discursive papers which examine the process and functionality of FtP panels. Currently no research has attempted to examine the decisions made or indeed how these decisions were arrived at within the following health and social care professions, Nursing, Paramedic Practice and Social work. Professional regulation for each of these professional groups is established through regulatory bodies. The regulation and determination of FtP of students on leading to registration is the role of the Higher Education Institution (HEI) and is less uniform in its approach. This may lead to disparity and the potential risk of inconsistency, unfair and unjust decisions for students. Aim: In order to gain a greater understanding FtP and professional conduct, this research study aimed to examine the decision-making process involved in ‘FtP’ panels for undergraduate health and social care students, comparing the decision-making process of students, lay person and practitioners (both experienced and inexperienced). This study explored the factors that influence the decision-making processes including experience and skills. Methods: Three simulated ‘FtP’ case studies were created and filmed to examine the decision-making process that takes place in panels for undergraduate nursing/paramedic/social work students. These were informed by real life cases and expertise of professionals within each of the professional groups. Actors were recruited for each of the case studies and the simulations were filmed. Debriefing of the simulation was conducted with the actors and the data collected was analysed using thematic analysis. The case studies were then examined and deconstructed by four focus groups for each case (twelve in total) with degrees of experience, lay people and students. This deconstruction also included an evaluation of the simulation and its potential use in the field of FtP. The data collected was analysed using thematic analysis and key emergent themes were identified. Findings: The findings highlighted two key areas. Firstly, the importance of those involved in panels, 'the people involved in FtP panel' and secondly the ‘decisions that were made during the panels’. These findings suggest that there are a number of identified roles within FtP. The influence of these roles is measured not by the role but the execution of the role and personalities are more influential than identified roles. There is a further suggestion that experience of FtP panels can influence decision-making processes and can make for lengthy yet robust decision-making and that when systematic approaches to decision-making are employed that there is clearer understanding of decisions it leads to more effective decision-making processes. Conclusion: Understanding student FtP decision-making and the influential factors involved in that process will inform HEIs in the overall management of FtP and consequently promote consistency and fairness in decision-making. This will be achieved by recognising the influential factors on the processes of FtP and considering these when FtP are conducted. It should prompt attention to the approaches adopted by individuals during FtP and the need for a more uniformed approach to FtP not dissimilar to that of the regulatory bodies approach. Implications: Recognising that personalities as well as identified roles are influential in the decision-making is important to consider when HEIs reflect panel composition. It is also essential to consider the experience and the skill when selecting panel members for FtP
Odour signals contain multi-modal information in the banded mongoose (Mungos mungo).
No full textCommunication can be crucial to the profitability of reproduction by allowing individuals to attract and select an appropriate mate. Across mammals, successful reproduction can depend on the ability of individuals to gain information such as relatedness, health parameters and breeding status from potential mates. Although visual and auditory signals are utilised, scent is a crucial and ancient form of communication yet, with the exception of certain model systems, we understand little of how it functions in wild mammals. This thesis will focus on the mechanistic role of odour signals: what information they contain and how they may facilitate reproductive decision-making in the banded mongoose (Mungos mungo). I use a wild but habituated population to conduct experimental odour presentations showing these mammals are capable of discriminating scents based on sex, familiarity, relatedness and female reproductive state. The ability of odours to encode such multi-modal information suggests they may facilitate key behavioural processes such as kin recognition, mate-choice and competitive interactions. However, the discrimination of pregnancy specifically implies scent cues function within reproductive decision-making, attracting males to receptive mates. The gastro-intestinal parasite community of this banded mongoose population was also screened, allowing the ability of odour cues to advertise parasitic infection to be tested. Observations show highly parasitised individuals scent-mark less frequently, suggesting marking behaviour indicates quality in terms of parasite burdens. Furthermore, experimental odour presentations show that banded mongooses exhibit behavioural aversions toward odours of heavily infected individuals. Scent cues, in the banded mongoose system, thus appear to encode a multitude of information relevant to reproduction
PTF13efv - An Outburst 500 Days Prior to the SNHUNT 275 Explosion and Its Radiative Efficiency
Full text linkThe American Astronomical Society. All rights reserved..The progenitors of some supernovae (SNe) exhibit outbursts with super-Eddington luminosities prior to their final explosions. This behavior is common among SNe IIn, but the driving mechanisms of these precursors are not yet well-understood. SNHunt 275 was announced as a possible new SN during 2015 May. Here we report on pre-explosion observations of the location of this event by the Palomar Transient Factory (PTF) and report the detection of a precursor about 500 days prior to the 2015 May activity (PTF 13efv). The observed velocities in the 2015 transient and its 2013 precursor absorption spectra are low (1000-2000 km s-1), so it is not clear yet if the recent activity indeed marks the final disruption of the progenitor. Regardless of the nature of this event, we use the PTF photometric and spectral observations, as well as Swift-UVOT observations, to constrain the efficiency of the radiated energy relative to the total kinetic energy of the precursor. We find that, using an order-of-magnitude estimate and under the assumption of spherical symmetry, the ratio of the radiated energy to the kinetic energy is in the range of 4 x 10-2 to 3.4 x 103. © 2016
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