20 resultados para ALKALI PROMOTION

em Aston University Research Archive


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Mg-Al hydrotalcite coatings have been grown on alumina via a novel alkali- and nitrate-free impregnation route and subsequent calcination and hydrothermal treatment. The resulting Mg-HT/AlO catalysts significantly outperform conventional bulk hydrotalcites prepared via co-precipitation in the transesterification of C-C triglycerides for fatty acid methyl ester (FAME) production, with rate enhancements increasing with alkyl chain length. This promotion is attributed to improved accessibility of bulky triglycerides to active surface base sites over the higher area alumina support compared to conventional hydrotalcites wherein many active sites are confined within the micropores. © 2014 The Royal Society of Chemistry.

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It has been previously established that alkali silica reaction (ASR) in concrete may be controlled by blending Portland cement with suitable hydraulic or pozzolanic materials. The controlling mechanism has been attributed to the dilution of the cement's alkali content and reduced mobility of ions in concrete's pore solution. In this project an attempt has been made to identify the factors which influence the relative importance of each mechanism in the overall suppression of the reaction by the use of blended cements. The relationship between the pore solution alkalinity and ASR was explored by the use of expansive mortar bars submerged in alkaline solutions of varying concentration. This technique enabled the blended cement's control over expansion to be assessed at given `pore solution' alkali concentrations. It was established that the cement blend, the concentration and quantity of alkali present in the pore solution were the factors which determined the rate and extent of ASR. The release of alkalis into solution by Portland cements of various alkali content was studied by analysis of pore solution samples expressed from mature specimens. The specification for avoiding ASR by alkali limitation, both by alkali content of cement and the total quantity of alkali were considered. The effect on the pore solution alkalinity when a range of Portland cements were blended with various replacement materials was measured. It was found that the relationship between the type of replacement material, its alkali content and that of the cement were the factors which primarily determined the extent of the pore solution alkali dilution effect. It was confirmed that salts of alkali metals of the kinds found as common concrete contaminants were able to increase the pore solution hydroxyl ion concentration significantly. The increase was limited by the finite anion complexing ability of the cement.

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In the UK, Open Learning has been used in industrial training for at least the last decade. Trainers and Open Learning practitioners have been concerned about the quality of the products and services being delivered. The argument put forward in this thesis is that there is ambiguity amongst industrialists over the meanings of `Open Learning' and `Quality in Open Learning'. For clarity, a new definition of Open Learning is proposed which challenges the traditional learner-centred approach favoured by educationalists. It introduces the concept that there are benefits afforded to the trainer/employer/teacher as well as to the learner. This enables a focussed view of what quality in Open Learning really means. Having discussed these issues, a new quantitative method of evaluating Open Learning is proposed. This is based upon an assessment of the degree of compliance with which products meet Parts 1 & 2 of the Open Learning Code of Practice. The vehicle for these research studies has been a commercial contract commissioned by the Training Agency for the Engineering Industry Training Board (EITB) to examine the quality of Open Learning products supplied to the engineering industry. A major part of this research has been the application of the evaluation technique to a range of 67 Open Learning products (in eight subject areas). The findings were that good quality products can be found right across the price range - so can average and poor quality ones. The study also shows quite convincingly that there are good quality products to be found at less than 50. Finally the majority (24 out of 34) of the good quality products were text based.

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Recognition of the contribution of small firms to the UK economy has grown considerably since 1995 when this research first began. The poor record of small firms in managing health and safety effectively has caused concern, and efforts made to improve knowledge and awareness of the target group through various initiatives have had some success. This research thesis attempts to identify the range of intervention routes and methods available to reach the target group, and to consider ways of evaluating the outcome of such efforts. Various interventions were tested with small firms, including a Workshop; use of Questionnaires; short postal Reply Slip survey; leading to a closer evaluation of a specific industry- the Licensed Trade. Attitudes and beliefs of the sample were identified, and observations carried out to consider actions taken by workers and others in the workplace. These empirical research findings were used to develop the theme of Primary and Secondary interventions intended to change behaviours, and to confirm assumptions about what small firms currently do to manage health and safety risks. Guidance for small firms was developed as a Secondary intervention tool to support Primary interventions, such as inspection or insurance provision.

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A group of lithologically varied UK aggregates have been incorporated into concrete prisms of variable alkali content to ascertain the alkali levels at which significant ASR first occurs at 38oC and 100% RH. Petrographical analysis was used to establish the source of reactivity. The results of these expansion tests showed that significant ASR can develop with certain aggregates at initial alkali levels as low as 3.5 kg/m3 Na2Oe. Similar prisms were made at initial alkali levels, well above, on and just below the alkali thresholds for each aggregate. These prisms were placed in salt solution to establish the effects of ASR. The results showed that an external source of NaCl does accentuate ASR in high alkali mixes. However, in low alkali mixes the ASR initiated was even greater than that developed by the high alkali mixes. It was proposed that an `initial alkali pessimum' existed for each aggregate type for specimens placed in salt solution. Electron microprobe analysis of the ASR gels from concretes immersed in salt solution, showed that two compositionally varied gel suites develop. The first suite was derived from ASR caused by the initial alkalis in a concrete mix and was identical to ASR gels derived from the various concretes when immersed in distilled water. The second suite was developed by alkalis derived from a reaction between NaCl and the C3A component of the cement paste. It was demonstrated that the `initial alkali pessimum' was probably due to a combination of these two ASR types at the alkali threshold point where both suites of ASR gel can develop. Equivalent mixes were made with a 25% replacement of the cement by pulverised fuel ash (pfa) to establish whether alkalis released from the pfa could initiate ASR in otherwise non-reactive low alkali mixes. The addition of air entrainment to reactive concrete mixes was also examined as a method of suppressing ASR.

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Liberalisation has become an increasingly important policy trend, both in the private and public sectors of advanced industrial economies. This article eschews deterministic accounts of liberalisation by considering why government attempts to institute competition may be successful in some cases and not others. It considers the relative strength of explanations focusing on the institutional context, and on the volume and power of sectoral actors supporting liberalisation. These approaches are applied to two attempts to liberalise, one successful and one unsuccessful, within one sector in one nation – higher education in Britain. Each explanation is seen to have some explanatory power, but none is sufficient to explain why competition was generalised in the one case and not the other. The article counsels the need for scholars of liberalisation to be open to multiple explanations which may require the marshalling of multiple sources and types of evidence.

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The atomic-scale structure of Bioglass and the effect of substituting lithium for sodium within these glasses have been investigated using neutron diffraction and solid state magic angle spinning (MAS) NMR. Applying an effective isomorphic substitution difference function to the neutron diffraction data has enabled the Na-O and Li-O nearest-neighbour correlations to be isolated from the overlapping Ca-O, O-(P)-O and O-(Si)-O correlations. These results reveal that Na and Li behave in a similar manner within the glassy matrix and do not disrupt the short range order of the network former. Residual differences are attributed solely to the variation in ionic radius between the two species. Successful simplification of the 2

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Peter, a 45 year old male, enters the pharmacy and asks, 'do you have something to stop a cough?' On questioning you find out that Peter has an irritating cough that has been off and on for the past few weeks since winter started. He coughs up phlegm every now and then, mostly upon waking. He has tried some cough mixture that he bought at the supermarket but is looking for something stronger. He states that he does not have any medical history or allergies and does not take any medication. He does feel that he can't exercise as much as he used to as he gets more breathless these days.

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As an increasingly popular medium by which to access health promotion information, the Internet offers significant potential to promote (often individualized) health-related behavioral change across broad populations. Interactive online health promotion interventions are a key means, therefore, by which to empower individuals to make important well being and treatment decisions. But how ldquohealthyrdquo are interactive online health promotion interventions? This paper discusses a literature review (or ldquohealth checkrdquo) of interactive online health interventions. It highlights the types of interactive interventions currently available and identifies areas in which research attention is needed in order to take full advantage for the Internet for effective health promotion.

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Extant research on the decomposition of unit sales bumps due to price promotions considers these effects only within a single product category. This article introduces a framework that accommodates specific cross-category effects. Empirical results based on daily data measured at the item/SKU level show that the effects of promotions on sales in other categories are modest. Between-category complementary effects (20%) are, on average, substantially larger than between-category substitution effects (11%). Hence, a promotion of an item has an average net spin-off effect of (20 - 11 =) 9% of its own effect. The number of significant cross-category effects is low, which means that we expect that, most of the time, it is sufficient to look at within-category effects only. We also find within-category complementary effects, which implies that competitive items within the category may benefit from a promotion. We find small stockpiling effects (6%), modest cross-item effects (22%), and substantial category-expansion effects (72%). The cross-item effects are the result of cross-item substitution effects within the category (26%) and within-category complementary effects (4%). Approximately 15% (= 11% / 72%) of the category-expansion effect is due to between-category substitution effects of dependent categories.

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As an increasingly popular medium by which to access health promotion information, the Internet offers significant potential to promote (often individualized) health-related behavioral change across broad populations. Interactive online health promotion interventions are a key means, therefore, by which to empower individuals to make important well being and treatment decisions. But how ldquohealthyrdquo are interactive online health promotion interventions? This paper discusses a literature review (or ldquohealth checkrdquo) of interactive online health interventions. It highlights the types of interactive interventions currently available and identifies areas in which research attention is needed in order to take full advantage for the Internet for effective health promotion.

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In this paper, we examined the interactive effects of two contexts—participation and intellectual stimulation, and promotion focus on creativity. On the basis of a multi-organization sample of 213 employees, we tested and found that although promotion focus was positively related to creativity, the relationship between promotion focus and creativity was most positive when both participation and leader intellectual stimulation were high. We discuss the way contexts in combination influence employee creativity for promotion-oriented individuals, through increasing decision latitude as well as stimulating and promoting creativity. Copyright © 2011 John Wiley & Sons, Ltd.

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