54 resultados para Isostatic pressing

em QUB Research Portal - Research Directory and Institutional Repository for Queen's University Belfast


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This study investigates the influence of process parameters on the fluidised hot melt granulation of lactose and PEG 6000, and the subsequent tablet pressing of the granules. Granulation experiments were performed to assess the effect of granulation time and binder content of the feed on the resulting granule properties such as mass mean granule size, size distribution, granule fracture stress, and granule porosity. These data were correlated using the granule growth regime model. It was found that the dominant granule growth mechanisms in this melt granulation system were nucleation followed by steady growth (PEG 10–20% w/w). However, with binder contents greater than 20% w/w, the granulation mechanism moved to the “over-wet massing” regime in which discrete granule formation could not be obtained. The granules produced in the melt fluidised bed process were subsequently pressed into tablets using an industrial tablet press. The physical properties of the tablets: fracture stress, disintegration time and friability were assessed using industry standards. These analyses indicated that particle size and binder content of the initial granules influenced the mechanical properties of the tablets. It was noted that a decrease in initial granule size resulted in an increase in the fracture stress of the tablets formed.

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Cross-border (North/South) co-operation between the Republic of Ireland and Northern Ireland was an indelible feature of the form of governance provided by the Belfast Good Friday Agreement (1998). Previous efforts to establish North/South co-operation had all foundered but the establishment and initial operation of the Agreement's cross-border institutions proved to be uncontroversial. However, during its implementation, other areas of the Agreement gave Ulster unionists more pressing cause for concern. These areas of concern included the release of paramilitary prisoners, police reform, the 'decommissioning' of Irish Republican Army (IRA) weaponry, and the unionist perception that the 'Britishness of Northern Ireland' was being actively eroded. These concerns served to emphasise and strengthen political and cultural borders between communities at a regional and local level within Northern Ireland. They also threatened the pro-Agreement unionists' contestation of unionist ideological orthodoxy, a contestation that was undertaken in an attempt to adapt the Ulster unionist identity to the shifting thresholds of the state.

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Since the introduction of molecular computation1, 2, experimental molecular computational elements have grown3, 4, 5 to encompass small-scale integration6, arithmetic7 and games8, among others. However, the need for a practical application has been pressing. Here we present molecular computational identification (MCID), a demonstration that molecular logic and computation can be applied to a widely relevant issue. Examples of populations that need encoding in the microscopic world are cells in diagnostics or beads in combinatorial chemistry (tags). Taking advantage of the small size9 (about 1 nm) and large 'on/off' output ratios of molecular logic gates and using the great variety of logic types, input chemical combinations, switching thresholds and even gate arrays in addition to colours, we produce unique identifiers for members of populations of small polymer beads (about 100 m) used for synthesis of combinatorial libraries10, 11. Many millions of distinguishable tags become available. This method should be extensible to far smaller objects, with the only requirement being a 'wash and watch' protocol12. Our focus on converting molecular science into technology concerning analog sensors13, 14, turns to digital logic devices in the present work.

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Despite progress in defining a pathogenic role for amyloid beta protein (Abeta) in Alzheimer's disease, orally bioavailable compounds that prevent its effects on hippocampal synaptic plasticity and cognitive function have not yet emerged. A particularly attractive therapeutic strategy is to selectively neutralize small, soluble Abeta oligomers that have recently been shown to mediate synaptic dysfunction. METHODS: Using electrophysiological, biochemical, and behavioral assays, we studied how scyllo-inositol (AZD-103; molecular weight, 180) neutralizes the acutely toxic effects of Abeta on synaptic function and memory recall. RESULTS: Scyllo-inositol, but not its stereoisomer, chiro-inositol, dose-dependently rescued long-term potentiation in mouse hippocampus from the inhibitory effects of soluble oligomers of cell-derived human Abeta. Cerebroventricular injection into rats of the soluble Abeta oligomers interfered with learned performance on a complex lever-pressing task, but administration of scyllo-inositol via the drinking water fully prevented oligomer-induced errors. INTERPRETATION: A small, orally available natural product penetrates into the brain in vivo to rescue the memory impairment produced by soluble Abeta oligomers through a mechanism that restores hippocampal synaptic plasticity.

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X-ray analysis of ferroelectric thin layers of Ba1/2Sr1/2TiO3 with different thicknesses reveals the presence of strain gradients across the films and allows us to propose a functional form for the internal strain profile. We use this to calculate the influence of strain gradient, through flexoelectric coupling, on the degradation of the ferroelectric properties of films with decreasing thickness, in excellent agreement with the observed behavior. This paper shows that strain relaxation can lead to smooth, continuous gradients across hundreds of nanometers, and it highlights the pressing need to avoid such strain gradients in order to obtain ferroelectric films with bulklike properties.

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Understanding climate change and its potential impact on species, populations and communities is one of the most pressing questions of twenty-fi rst-century conservation planning. Palaeobiogeographers working on Cenozoic fossil records and other lines of evidence are producing important insights into the dynamic nature of climate and the equally dynamic response of species, populations and communities. Climatic variations ranging in length from multimillennia to decades run throughout the palaeo-records of the Quaternary and earlier Cenozoic and have been shown to have had impacts ranging from changes in the genetic structure and morphology of individual species, population sizes and distributions, community composition to large-scale bio-diversity gradients. The biogeographical impacts of climate change may be due directly to the effects of alterations in temperature and moisture on species, or they may arise due to changes in factors such as disturbance regimes. Much of the recent progress in the application of palaeobiogegraphy to issues of climate change and its impacts can be attributed to developments along a number of still advancing methodological frontiers. These include increasingly finely resolved chronological resolution, more refi ned atmosphere-biosphere modelling, new biological and chemical techniques in reconstructing past species distributions and past climates, the development of large and readily accessible geo-referenced databases of biogeographical and climatic information, and new approaches in fossil morphological analysis and new molecular DNA techniques.

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In the popular mind, the concept of 'emigration' usually refers to people voluntarily leaving one country to go to another in search of a new and better life. It presupposes some degree of choice, although it is accepted that for many emigrants, such as those who left Ireland during the nineteenth century, there were few incentives to stay at home. Current scholarship on voluntary and forced movements of people demonstrates that the distinction between the categories of 'voluntary emigrant' and 'forced exile' is often blurred. Orm Overland's study of refugee communities in the United States highlights the fact that, although the differences between the 'emigrant' and the 'exile' may be clear in extreme cases, this is not always true, as there may be 'pressing political or economic reasons behind a decision to emigrate'. Migration scholars Jan Lucassen and Leo Lucassen also question the adequacy of conceptual models of migration based on what Lindsay Proudfoot and Dianne Hall refer to as the 'straightforward binarism between free and unfree emigration'. The questions raised by these scholars are very relevant to the study of Irish people who left their country during the second half of the nineteenth century immediately after they had been discharged from prison or from Dundrum. Their stories are discussed here against a background of substantial scholarship on emigration from Ireland and on the criminal justice system within Ireland. According to David Fitzpatrick, at least eight million men, women and children emigrated from Ireland between 1801 and 1921. This large-scale movement of people was generally characterised by the voluntary emigration of individuals who funded their own passages. However, it also included schemes of assisted emigration, funded variously by governments, landlords, the poor law authorities, earlier emigrants, and philanthropists. In addition, it included people who were transported from Ireland by means of the criminal justice system a practice that had originated in the seventeenth century. What is less well known is that after the end of transportation from Ireland to eastern Australia in 1853, to Bermuda in 1863 and to Western Australia in 1868, Irish convicts continued to be channelled towards emigration by being offered early release if they agreed to leave Ireland. These people, and especially the women among them, are the subject of this article.

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Movement-related potentials (MRPs) reflect increasing cortical activity related to the preparation and execution of voluntary movement. Execution and preparatory components may be separated by comparing MRPs recorded from actual and imagined movement. Imagined movement initiates preparatory processes, but not motor execution activity. MRPs are maximal over the supplementary motor area (SMA), an area of the cortex involved in the planning and preparation of movement. The SMA receives input from the basal ganglia, which are affected in Huntington's disease (HD), a hyperkinetic movement disorder. In order to further elucidate the effects of the disorder upon the cortical activity relating to movement, MRPs were recorded from ten HD patients, and ten age-matched controls, whilst they performed and imagined performing a sequential button-pressing task. HD patients produced MRPs of significantly reduced size both for performed and imagined movement. The component relating to movement execution was obtained by subtracting the MRP for imagined movement from the MRP for performed movement, and was found to be normal in HD. The movement preparation component was found by subtracting the MRP found for a control condition of watching the visual cues from the MRP for imagined movement. This preparation component in HD was reduced in early slope, peak amplitude, and post-peak slope. This study therefore reported abnormal MRPs in HD. particularly in terms of the components relating to movement preparation, and this finding may further explain the movement deficits reported in the disease.

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In this paper, the results of an empirical analysis of a set of 416 descriptive case studies published by corporate members of the UN Global Compact are presented. Although these cases cannot be viewed as representative of the Compact itself or of corporate social responsibility (CSR) and development in general, they can illustrate which kinds of projects are deemed appropriate as best practice examples among Compact members, and therefore indicate the direction, in which predominantly voluntary and business-led CSR might at best be evolving. To help contextualize the analysis, the paper starts with a brief overview of recent academic work on the strengths and limitations of CSR in the light of international development, followed by the empirical analysis of Compact case studies. The results raise doubts regarding the general suitability of contemporary CSR initiatives to tackle some of the most pressing developmental challenges. Instead, only certain topics are commonly addressed, while a number of issues such as anti-corruption measures or labour rights are underrepresented in the case study sample. Regarding the target regions of the best practice examples, the majority is reported on activities based in OECD countries and a small number of emerging markets such as South Africa, India or China, while neglecting other regions such as sub-Saharan Africa (excluding South Africa). From a European Union policy perspective, these results indicate that there is a role to play for the state in order to create a better fit between CSR agendas and the actual developmental needs in the South.

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The modern world is replete with ethical challenges of Orwellian proportions. The violation of human rights and misrecognition of identities are two of the most pressing examples. In this paper, the ethical theories of Habermas and Honneth are aligned as a way of addressing these specific challenges within social work. It is suggested that these theories are complementary, mutually rectifying and concordant at the meta-ethical level of analysis. The alignment is also justified, pargmatically, through the construction of three hypothetical vignettes demonstrating different kinds of practice dilemmas. The need for egalitarian communication and the imperative to recognise human identity in all its dimensions subsequently emerge as the two foundation stones for ethical deliberation in social work.

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Summary: This article outlines a framework for approaching ethical dilemmas arising from the development, evaluation and implementation of child welfare policies. As such, it is relevant to policy-makers, social researchers and social workers. The central tenets of the framework are developed by drawing on ideas from moral philosophy and critical social theory. These ideas are presented as axioms, theorems and corollaries, a format which has been employed in the social sciences to offer a rational justification for a set of claims. • Findings: This process of reasoning leads to four principle axioms that are seen to shape the ethical scrutiny of social policy: 1) problematizing knowledge; 2) utilizing structured forms of inquiry to enhance understanding; 3) engendering enabling communication with those affected by the ethical concern; and 4) enhancing self-awareness. • Applications: The four axioms are then applied, by way of example, to the current and contentious, 'third way' policy of mandated prevention in child welfare, where the aim is to obviate deleterious outcomes in later life. It is argued that the framework can be applied beyond this specific concern to other pressing, ethical challenges in child welfare.

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The transition of foster youth from state care to independent living has received increased research, practice, and policy attention in the United States and in many other countries. Most contributions to this literature have focused on documenting poor outcomes across various dimensions of need in the young people's lives whereas little attention has been given to the policy context in which the responses to those needs are being developed. In this article, we argue that there is a pressing need for better understanding of how the policy context can both promote and impede the development of appropriate services. To illustrate our argument, we use Northern Ireland as a policy case study both because of recent initiatives underway there in regard to youth transitions from state care and because of the heightened political sensibilities associated with it as a society. We draw attention to the socio-political historical context, a number of intersecting social policies, and the place of social work as a key occupation involved in delivering service improvements. We conclude by suggesting that this case study not only highlights the need to address similar aspects of the policy on youth transition frorn state care in the United States but also demonstrates the benefits of reflecting on policy development and implementation elsewhere in the world.