3,504 research outputs found
Ancient tin production: Slags from the Iron Age Carvalhelhos hillfort (NW Iberian Peninsula)
Provenance and production of tin in the Ancient World has since long been a major topic of discussion among archaeologists. In Western Europe, where significant tin ore (cassiterite) deposits are known, only a few remains of ancient tin production, such as tin slags, have been detected. In the present work, elemental and microstructural analyses by WDXRF, SEM-EDS and XRD were performed on recently recognised tin slags from the Iron Age Carvalhelhos hillfort located in NW Iberia, a territory that represents the largest extension with tin mineralisation in Western Europe. Elemental and microstructural characterisation of cassiterite collected in a pilot field survey in the region of the hillfort are presented and discussed, as well as two ceramic fragments that could be part of a smelting structure and an iron slag from the settlement. Results show that the tin slags have variable but high contents in Sn, similarly to Pre-Medieval tin slags found in other Western European areas, but also high contents of Ta and Nb, which specifically distinguish them from other tin slags, such as those found in SW Britain. Tin ores from the hillfort region frequently have Ta and Nb in cassiterite solid solution or as inclusions of columbite group minerals, relating well with the Carvalhelhos tin slags. Up to present, the Carvalhelhos slags are amongst the very few ancient tin slags known in Western Europe, and their study can contribute to a better knowledge on ancient tin sources and trade routes
Nanotubos de carbono para processos de tratamento de águas
Oxidantes como o oxigénio molecular, o ozono e o peróxido de hidrogénio são utilizados nos
tratamentos de águas residuais por via química oxidativa podendo atuar por si próprios, ou ser
ativados por meio de um catalisador, ou fotocatalisador, adequado. Sendo os tratamentos
químicos processos definitivos por natureza, é possível apontar à mineralização completa dos
poluentes presentes. Contudo, raramente é esse o caso, quando se procura uma solução
racional do ponto de vista económico. No caso de efluentes industriais recorre-se muitas vezes a tratamentos diferenciados, com vista a uma degradação oxidativa parcial
GRASS UTILIZATION IN GROWING FINISHING BÍSARO PIGS (85-107 KG). PERFORMANCE AND CARCASS COMPOSITION
The use of different quantities of vegetables, forages or fresh grass as fodder for growing-finishing pigs is an important factor of the northern Portugal traditional system. The increasing development of swine production in outdoor systems, extensive and organic production, turns to upcoming natural diets, in which grass performs a significant part. With regard to this, some investigation has been made concerning the use of fibre-rich feed ingredients in pig nutrition. Metabolic effects of its ingestion are analysed concerning different sights (economical, social, environmental and physiological ones).
The aim of this work was to study the effects of grass utilization in the diets on performances of finishing Bísaro pigs. A total of 22 pigs (16 castrated males and 6 females) was housed outdoor and fed ad libitum (37 – 85 kg live weight) with a growing diet and then transferred to an indoor system (with free access to an outdoor area) for 49 days, according to 3 different treatments: 100% concentrate (C), 75% concentrate + ad libitum grass (CE75), 50% concentrate + ad libitum grass (CE50). The grass was supplied and its intake registered on a daily basis. Every 14 days, the pigs were weighted and their back fat (P2 in vivo) measured. After slaughter (average weight of 107 kg LW), yield and ½ left carcass characteristics were controlled. During the outdoor growing phase, the ADG was 513 g/day. During the indoor finishing phase, the increase grass intake was proportional to the reduction of concentrate in the diet. The ADG (g) and the fat deposition (P2 cm) were significantly different (P<0,05) in the 3 treatments (ADG: C=641, CE75=467, CE50=356 and: C=11,4, CE75=+9,5, CE50=+6,2). The empty body weight (kg) was also proportional to the intake of concentrate (C=116,2; CE75=107,7; CE50=102,2). Comparatively to the weight of the body parts, pigs that had higher intake of grass and lower of concentrate showed a higher % of shoulder (P<0,05; C=20,4, CE75=21,7, CE50=22,2) and the pH45min of CE carcasses was significantly higher (P<0,05). As a conclusion, concentrate substitution for grass showed a slower growing rate, thinner carcasses and a high technological quality.
Neverthelles variability (CV %) of the productive parameters at the end of this study were higher in the treatments that included grass: live weight (C= 10,5%; C75=10,7%; C50=14,3%), finishing ADG (C=24%; C75=37%, C50=42%), and final fat (C=37%; C75=32%, C50=52%). These values suggest that the utilization of fibrous feeds in growing-finishing swine may be one of the possible explanations of the more heterogeneous products and carcasses found in the traditional or extensive systems, common users of fibrous feeds in the carcass finishing phase
Equity Valuation : LinkedIn Corp
The aim of this dissertation was to reach Linkedln's Equity Fair Value. Through an analysis of all methods available, the ones chosen were Adjusted Present Value and Relative Valuation through a combination of Equity Multiples, Transaction Multiples, Trading Multiples and Social Network Specific Multiples (Monthly Active Users).
Adjusted Present Value valuation yielded a per share value for Linkedln of 143, Transaction Multiples gave a 216,14 and Monthly Active Users a quite distant 249,82. Which is in contrast with J. P. Morgan's Buy recommendation of 186,77. Pelo método de Avaliação Comparativa obtivemos valores diferentes consoante o conjunto de múltiplos analisado. Múltiplos de Capital Próprio resultaram num valor de 87,57. Por outro lado Múltiplos de Preço apresentaram uma média de 6,35.
Para atingir maior robustez foi executada uma análise de sensibilidade incluindo análise de cenários múltiplos, com o fim de testar várias projecções de receitas, e variações em variáveis específicas.
Por fim, foi efectuada uma comparação com um relatório da J. P. Morgan para comparar os resultados desta dissertação com o de um banco de investimento. A conclusão final da dissertação foi de recomendar Venda sobre o LinkedIn, pois esta apresentou um preço de fecho no dia 1 de Dezembro de 2015 de 300
Towards the development of water purification technologies using carbon materials and metal oxides
The abatement of environrnental pollutants, and especially the availability of clean water in sufficient
amounts, are important issues in large and industrialized cities as well as in less developed regions.
Advanced oxidation processes (AOPs) can decisively contribute to water purification. As a
consequence, the development of effective catalysts has prompted enormous attention in materiais
science. Carbon materiais have been widely employed in AOPs, usually as catalyst supports and less
commoniyas catalysts on their OWD. An overview ofthe different steps involved in the development of
suitable catalysts from the nano- to the macro-scale will be presented in this work, with particular
emphasis on the use of carbon materiais for wet air oxidation, wet peroxide oxidation, ozonation, and
photocatalysis. Our studies show that carbon materiais with no added metais can be used as efficient
catalysts in these processes, including activated carbons, carbon xerogels, multi-walled carbon
nanotubes, as well as carbon foarns and fibres [1-4]. The work under progress aims at the development
of more efficient and stable carbon materiais with tuned surface chellÚstry. In the particular case of
photocatalysis, titaninrn dioxide (Ti02) is the most frequently used catalyst; however, aiming at solar
applications, there is a drive to improve its activity under near-UVNis irradiation. Our recent work in
this field is focused on the development of active and stable carbon-Ti02 nanostructured composites,
including diverse carbon materiais, such as fullerenes, carbon nanotubes, nanodiamonds, graphene and
its derivatives [5
MS prevalence and patients’ characteristics in the district of Braga, Portugal
Article ID 895163Multiple Sclerosis (MS) is a chronic autoimmune disease of the Central Nervous System causing inflammation and neurodegeneration. There are only 3 epidemiological studies in Portugal, 2 in the Centre and 1 in the North, and there is the need to further study MS epidemiology in this country. The objective of this work is to contribute to the MS epidemiological knowledge in Portugal, describing the patients’ epidemiological, demographic, and clinical characteristics in the Braga district of Portugal. This is a cross-sectional study of 345 patients followed in two hospitals of Braga district. These hospitals cover a resident population of 866,012 inhabitants. The data was collected from the clinical records, and 31/12/2009 was established as the prevalence day. For all MS patients, demographic characteristics and clinical outcomes are reported. We have found an incidence of 2.74/100,000 and a prevalence of 39.82/100,000 inhabitants. Most patients have an EDSS of 3 or lower and a mean age of 42 years. The diagnosis was done at mean age of 35, with RRMS being the disease type in more than 80% of patients. In this cohort, we found a female : male ratio of 1.79. More than 50% of patients are treated with Interferon β-1b IM or IFNβ-1a SC 22 μg.This research was partially supported by the Research Centre of Mathematics of the University of
Minho through the FEDER Funds ”Programa Operacional Fatores de Competitividade – COMPETE'',
and by the Portuguese Funds through FCT -”Fundação para a Ciência e Tecnologia” within the
Project Est-C/MAT/UI0013/2011
Carbon nanotubes as base materials for water treatment processes
Chemical wastewater treatments are dependent on the addition of auxiliary oxidants, which may include
molecular oxygen, ozone, and hydrogen peroxide, working on their own, or activated by means of a
specialized catalyst or photocatalyst. Chemical treatments are by nature definitive processes, since they can
lead to complete mineralization of the existing pollutants. However, this is seldom the case, when looking for
a rational solution from the socio-economical point of view. In the case of industrial effluents, special
treatments are often required, even when only a partial oxidative degradation is targeted, due to the complex
nature of the pollutants (e.g. dyes, pharmaceuticals, oils, organics, inorganics and bio-compounds).
Some compounds, like nitrophenols, are particularly refractory to aerobic biodegradation and in addition to
that toxic, requiring strong oxidative solutions. Typical solutions are the thermal processes at elevated
temperatures and pressures, or using metal supported catalysts. Alternatively, it is possible to use
heterogeneous photocatalysis based on the efficient production of hydroxyl radicals. Somewhere between
these two limits lies the catalytic wet peroxide oxidation (CWPO), an advanced oxidation process (AOP)
involving the use of hydrogen peroxide (H2O2) as oxidation source and a suitable catalyst (typically iron
based catalysts). The main role of the catalyst is to promote H2O2 decomposition through the formation of
hydroxyl radicals (HO●) with high oxidizing potential, effective in the destruction of a huge range of
pollutants [1,2]. This type of technology is especially attractive due to the use of mild conditions, simple
equipment and the environmental safe oxidant H2O2.Work supported by project PTDC/AAC-AMB/110088/2009 and partially by project PEst–C/EQB/LA0020/2011, financed by FEDER through COMPETE - Programa Operacional Factores de
Competitividade and by FCT - Fundação para a Ciência e a Tecnologia
The experience with economic-demographic models for Brazil description and results
Unavailable.Indisponível
Desenvolvimento de xerogéis de carbono magnéticos para o processo de oxidação catalítica com peróxido de hidrogénio
Neste trabalho é apresentada uma nova metodologia para a preparação de xerogéis de carbono magnéticos.
Como demonstrado através da caraterização efetuada, foi possível obter materiais com propriedades
bastante distintas apenas por inclusão de precursores de ferro e/ou cobalto durante a reação de
policondensação sol-gel entre o resorcinol e o formaldeído, seguida da redução térmica a 800 oC em
atmosfera de N2. Tendo em conta o desempenho dos materiais desenvolvidos na oxidação catalítica com
peróxido de hidrogénio (CWPO) de soluções concentradas (5 g L-1) de 4-nitrofenol (4-NP) foi demonstrado
um importante efeito sinérgico entre as duas fases sólidas decorrente da incorporação dos metais nos
xerogéis de carbono. Concretamente, conseguiu-se uma remoção completa de 4-NP em apenas 1 h de reação
na presença de xerogel de carbono com ferro e cobalto incorporados na sua estrutura (CX/CoFe), para
soluções contendo [4-NP]0 = 5 g L-1, [H2O2]0 = 17.8 g L-1 (estequiométrica), t = 50 oC, pH = 3 e na presença de
2.5 g L–1 de CX/CoFe (correspondendo a uma razão mássica poluente/catalisador de 2).
Os resultados apresentados podem abrir caminho ao desenvolvimento de materiais com elevados
desempenhos noutras aplicações catalíticas, para além dos processos de CWPO.A new method for the preparation of magnetic carbon xerogels is presented in this work. As shown from the
characterization performed, it was possible to obtain materials with very different properties just by inclusion
of iron and/or cobalt precursors during the sol-gel polycondensation of resorcinol and formaldehyde,
followed by thermal reduction at 800 oC under N2 atmosphere. Taking into account the performance of the
developed materials in the catalytic wet peroxide oxidation (CWPO) of highly concentrated 4-nitrophenol
solutions (4-NP, 5 g L-1), an important synergistic effect between phases was shown to arise from the inclusion
of metals in the carbon xerogels. Specifically, complete 4-NP removal was obtained in only 1 h of reaction in
the presence of the magnetic carbon xerogel with iron and cobalt embedded in its structure (CX/CoFe), with
[4-NP]0 = 5 g L-1, [H2O2]0 = 17.8 g L-1 (stoichiometric), T = 50 oC, pH = 3, in the presence of 2.5 g L–1 CX/CoFe
(corresponding to a pollutant/catalyst mass ratio of 2).
The results shown may open future prospects for the development of materials with high performances in
other catalytic applications, in addition to the CWPO processes.O presente trabalho foi financiado pela
Fundação para a Ciência e a Tecnologia (FCT) e
FEDER através do COMPETE 2020 (Projeto
UID/EQU/50020/2013 - POCI-01-0145-FEDER-
006984). R.S. Ribeiro agradece a bolsa individual
de doutoramento FCT SFRH/BD/94177/2013, com
financiamento da FCT e do Fundo Social Europeu
(através do Programa Operacional Potencial
Humano e QREN). A.M.T. Silva agradece ao
Programa Investigador FCT (IF/01501/2013), com
financiamento do Fundo Social Europeu e
Programa Operacional Potencial Humano.info:eu-repo/semantics/publishedVersio
Development of magnetically recoverable carbon nanocomposites for the catalytic wet peroxide oxidation of 4-nitrophenol solutions
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