83 resultados para PFA


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A comparative study has been made of the radiation grafting of styrene onto poly(tetrafluoroethylene-co-perfluoropropyl vinyl ether) (PFA) and polypropylene (PP) substrates, using the simultaneous irradiation method. Effects of grafting conditions such as monomer concentrations, type of solvent, dose rate and irradiation dose on the grafting yield were investigated. Under the same grafting conditions it was found that a higher degree of grafting of styrene was obtained using a mixture of dichloromethane/methanol solvents for PFA and methanol for PP and the degree of grafting was higher in PP than in PFA at all doses. However, the micro-Raman spectroscopy analysis of the graft revealed that, for the same degree of grafting, the penetration depth of the grafted polystyrene into the substrate was higher in PFA than in PP substrates. In both polymers the crystallinity was hardly affected by the grafting process and the degree of crystallinity decreased slightly with grafting dose. The dependence of the initial rate of grafting on the dose rate and the monomer concentration was found to be 0.6 and 1.4 order for PFA and 0.15 and 2.2 for PP, respectively. The degree of grafting increased with increasing radiation dose in both polymers. However, the grafting yield decreased with an increase in the dose rate. The increase in the overall grafting yield for PFA and PP was accompanied by a proportional increase in the penetration depth of the graft into the substrates. (C) 2003 Society of Chemical Industry.

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Fluoropolymers are known as chemically inert materials with good high temperature resistance, so they are often the materials of choice for harsh chemical environments. These properties arise because the carbon-fluorine bond is the strongest of all bonds between other elements and carbon, and, because of their large size, fluorine atoms can protect the carbon backbone of polymers such as poly(tetrafluoroethylene), PTFE, from chemical attack. However, while the carbon-fluorine bond is much stronger than the carbon hydrogen bond, the G values for radical formation on high energy radiolysis of fluoropolymers are roughly comparable to those of their protonated counterparts. Thus, efficient high energy radiation grafting of fluoropolymers is practical, and this process can be used to modify either the surface or bulk properties of a fluoropolymer. Indeed, radiation grafted fluoropolymers are currently being used as separation membranes for fuel cells, hydrophilic filtration membranes and matrix substrate materials for use in combinatorial chemistry. Herein we present a review of recent studies of the high energy radiation grafting of fluoropolymers and of the analytical methods available to characterize the grafts. (C) 2003 Elsevier Ltd. All rights reserved.

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Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Química e Biológica

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Trabalho Final de Mestrado para obtenção do grau de Mestre em Engenharia Mecânica

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Dissertação para obtenção do Grau de Mestre em Bioorgânica

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Starting from Novabase’s challenge to launch in the UK Millennials a personal financial advisor mobile application, this work project aims to build a planning model to frame a business side of a launch strategy for mobile application in similar market and category. This study culminates on the design of SPOSTAC planning model. The created framework is intended to effectively and efficiently plan a launch strategy, being structured based on seven sequential elements: Situation, Product, Objectives, Strategy, Tactics, Action, and Control.

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En las colecciones del IRTA-Mas Bové se han caracterizado más de 150 clones de nogal procedentes de prospección, material extranjero y de selecciones de distintos programas de mejora. El material se ha caracterizado agronómicamente siguiendo los descriptores del IPGRI (1994). Actualmente existen fichas descriptivas muy amplias de 43 accesiones. Toda esta información sobre el comportamiento del material vegetal en las condiciones climáticas de Tarragona, tiene interés a nivel científico y es muy válida para posibles plantaciones con nuevo material. El estudio de los caracteres de sensibilidad a Bacteriosis y afección de la caída prematura de flores (PFA), en dos decendencias de nogal de cruzamientos controlados, ha permitido obvervar que estos caracteres tienen una herencia compleja. Se ha establecido la virulencia de distintos aislados de Xanthomonas arboricola pv. juglandis, en nogal. Los aislados más virulentos se han utilizado para establecer un modelo de predicción, en condiciones de laboratorio, de esta bacteria en nogal. La temperatura a la que la severidad de la enfermedad es máxima es 26ºC. A esta temperatura un aumento en la duración del período de humedad relativa elevada de 0-24 horas, produce un aumento de la afección. En los próximos años, este modelo de predicción se validará en campo. Si los resultados son positivos, permitirán racionalizar los tratamientos para la Bacteriosis en las plantaciones de nogal. Los primeros resultados de un control de la iluminación en el interior de las copas de los árboles, realizado mediante medidas de iluminación interceptadas con un ceptómetro Delta T (SunScan), han puesto de manifiesto que la gran influencia de la luz en el crecimiento anual de las ramas. Así, en la formación y poda de los árbles hay que tener presente estos resultados, en especial en las formaciones en ejes libres, y favorecer la máxima entrada de luz en el interior de la copa de los árboles.

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This statistics release gives details of the waiting times for patients accessing cancer services at hospitals in Northern Ireland during the month of March 2008. The data contained within this release reports on the performance of all Health and Social Care Trusts in Northern Ireland, measured against the three Priorities for Action (PfA) targets for 2007/08 relating to waiting times for cancer services in Northern Ireland during March 2008. åÊ

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This joint PHA/HSCB Hidden Harm Action Plan - Responding to the needs of children born to and living with parental alcohol and drug misuse in Northern Ireland, has been prepared for the DHSSPS in response to the PfA target on Hidden Harm. The plan was approved by DHSSPS in October 2009.

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Personal and Public Involvement (PPI) is an essential component in the delivery of truly person centred services.�It is also a statutory duty.�The PHA has leadership responsibilities in respect of the implementation of PPI across HSC.�One of the ways in which the PHA discharges that leadership function, is through the Regional HSC PPI Forum.�This body brings together all HSC organisations, working alongside service users and carers, to bring a focus on involvement.�It promotes the sharing of best practice, identifies and tackles issues of common concern and providers a platform for the active participation of service users and carers.� Each year in response to a Priorities for Action (PFA) target, the PHA, working with HSC partners, service users and carers in the Forum, develop an Annual Report on PPI work taken forward through the Forum.The report for 2012/13 details progress in a number of important areas such as training, development of standards etc.

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This joint PHA/HSCB Hidden Harm Action Plan - Responding to the needs of children born to and living with parental alcohol and drug misuse in Northern Ireland, has been prepared for the DHSSPS in response to the PfA target on Hidden Harm. The plan was approved by DHSSPS in October 2009.

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RATIONALE The choice of containers for storage of aqueous samples between their collection, transport and water hydrogen (2H) and oxygen (18O) stable isotope analysis is a topic of concern for a wide range of fields in environmental, geological, biomedical, food, and forensic sciences. The transport and separation of water molecules during water vapor or liquid uptake by sorption or solution and the diffusive transport of water molecules through organic polymer material by permeation or pervaporation may entail an isotopic fractionation. An experiment was conducted to evaluate the extent of such fractionation. METHODS Sixteen bottle-like containers of eleven different organic polymers, including low and high density polyethylene (LDPE and HDPE), polypropylene (PP), polycarbonate (PC), polyethylene terephthalate (PET), and perfluoroalkoxy-Teflon (PFA), of different wall thickness and size were completely filled with the same mineral water and stored for 659?days under the same conditions of temperature and humidity. Particular care was exercised to keep the bottles tightly closed and prevent loss of water vapor through the seals. RESULTS Changes of up to +5 parts per thousand for d2H values and +2.0 parts per thousand for d18O values were measured for water after more than 1?year of storage within a plastic container, with the magnitude of change depending mainly on the type of organic polymer, wall thickness, and container size. The most important variations were measured for the PET and PC bottles. Waters stored in glass bottles with Polyseal (TM) cone-lined PP screw caps and thick-walled HDPE or PFA containers with linerless screw caps having an integrally molded inner sealing ring preserved their original d2H and d18O values. The carbon, hydrogen, and oxygen stable isotope compositions of the organic polymeric materials were also determined. CONCLUSIONS The results of this study clearly show that for precise and accurate measurements of the water stable isotope composition in aqueous solutions, rigorous sampling and storage procedures are needed both for laboratory standards and for unknown samples. Copyright (c) 2012 John Wiley & Sons, Ltd.

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Production flow analysis (PFA) is a well-established methodology used for transforming traditional functional layout into product-oriented layout. The method uses part routings to find natural clusters of workstations forming production cells able to complete parts and components swiftly with simplified material flow. Once implemented, the scheduling system is based on period batch control aiming to establish fixed planning, production and delivery cycles for the whole production unit. PFA is traditionally applied to job-shops with functional layouts, and after reorganization within groups lead times reduce, quality improves and motivation among personnel improves. Several papers have documented this, yet no research has studied its application to service operations management. This paper aims to show that PFA can well be applied not only to job-shop and assembly operations, but also to back-office and service processes with real cases. The cases clearly show that PFA reduces non-value adding operations, introduces flow by evening out bottlenecks and diminishes process variability, all of which contribute to efficient operations management.

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Emerging evidence suggests that the hypocretinergic system is involved in addictive behavior. In this study, we investigated the role of these hypothalamic neuropeptides in anxiety-like responses of nicotine and stress-induced reinstatement of nicotine-seeking behavior. Acute nicotine (0.8 mg/kg, s.c.) induced anxiogenic-like effects in the elevated plus-maze and activated the paraventricular nucleus of thehypothalamus (PVN) as revealed by c-Fos expression. Pretreatment with the hypocretin receptor 1 (Hcrtr-1) antagonist SB334867 orpreprohypocretin gene deletion blocked both nicotine effects. In the PVN, SB334867 also prevented the activation of corticotrophinreleasing factor (CRF) and arginine-vasopressin (AVP) neurons, which expressed Hcrtr-1. In addition, an increase of the percentage of c-Fos-positive hypocretin cells in the perifornical and dorsomedial hypothalamic (PFA/DMH) areas was found after nicotine (0.8 mg/kg,s.c.) administration. Intracerebroventricular infusion of hypocretin-1 (Hcrt-1) (0.75 nmol/1 l) or footshock stress reinstated a previouslyextinguished nicotine-seeking behavior. The effects of Hcrt-1 were blocked by SB334867, but not by the CRF1 receptor antagonistantalarmin. Moreover, SB334867 did not block CRF-dependent footshock-induced reinstatement of nicotine-seeking while antalarmin was effective in preventing this nicotine motivational response. Therefore, the Hcrt system interacts with CRF and AVP neurons in the PVN and modulates the anxiogenic-like effects of nicotine whereas Hcrt and CRF play a different role in the reinstatement of nicotineseeking.Indeed, Hcrt-1 reinstates nicotine-seeking through a mechanism independent of CRF activation whereas CRF mediates the reinstatement induced by stress.

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O objetivo deste trabalho foi estudar, por locos isoenzimáticos, a diversidade e a estrutura genética espacial de genótipos de Myracrodruon urundeuva em duas populações naturais, uma no Sudoeste (Selvíria-SEL) e outra no Sudeste (Paulo de Faria-PFA) do Brasil. Para isso, foram avaliados cinco sistemas isoenzimáticos, 25 e 30 indivíduos adultos das populações SEL e PFA, respectivamente. A estimativa da divergência genética entre populações foi baixa (=0,043). As heterozigosidades observada e esperada foram altas nas populações (0,317 e 0,511, respectivamente), e o excesso significativo de heterozigotos foi detectado na população PFA (= -0,252). A análise da distribuição genética espacial dos genótipos a partir do índice I de Moran revelou estruturação significativa até 5.224 m na população mais explorada (SEL, =0,09) e tendência à distribuição aleatória na população menos explorada (PFA, = -0,02). A provável causa da estruturação na população SEL foi a dispersão de sementes próxima às árvores-matriz, associada ao processo de recolonização a partir de sementes oriundas de poucos genótipos remanescentes. As implicações dos resultados são discutidas do ponto de vista da conservação e do melhoramento genético.