Tempos de espera cirúrgicos: situação em Portugal e determinantes

RESUMO - Objectivos Um dos problemas mais comuns nos sistemas de saúde e particularmente naqueles que têm uma estrutura predominantemente pública são os elevados Tempos Espera (TE) para cirurgia. Este projecto tem como principal objectivo identificar a importância relativa em Portugal das determinantes do TE cirúrgico. Metodologia Para clarificar essa importância, aplicou-se um questionário desenvolvido pelo Fraser Institute, utilizado para a análise anual dos TE no Canadá, recorrendo a um painel de peritos e através da realização da técnica Delphi, procurou-se consensualizar quais as determinantes das Listas Espera (LE), mais importantes. Para ilustrar a diversidade de perspectivas, recorreu-se também à análise de trabalhos realizados por inúmeras organizações, onde pudemos observar e recolher distintas abordagens, políticas e técnicas da questão das LE em países com diferentes tipos de sistemas de saúde. Resultados Os resultados obtidos revelam que os peritos consideraram a disponibilidade de tempo no Bloco Operatório (BO) e a de anestesiologistas, como as determinantes com maior impacto no aumento das LE. Conclusões Dos dados recebidos relativos ao Sistema Integrado Gestão Inscritos Cirurgia (SIGIC), bem como dos retirados de relatórios oficiais, concluímos que as LE cirúrgicas tiveram evolução positiva, nomeadamente na redução da mediana do TE da Lista Inscritos Cirurgia (LIC) (meses), no entanto, os objectivos dos Tempos Máximos Resposta Garantidos (TMRG) não estão a ser cumpridos. A análise das diferentes iniciativas e estratégias políticas para combater as LE, permitiu-nos sugerir caminhos a explorar, tendo como objectivo minorar o problema das LE: cuidados integrados, optimização da eficiência na utilização da capacidade instalada e maior aposta na cirurgia de ambulatório.

Contributo da curva de débito-volume na detecção da obstrução da via aérea central

RESUMO: Introdução: A obstrução da via aérea central (OVAC) refere-se a um processo patológico que conduz a limitação do fluxo de ar ao nível do espaço glótico e subglótico, traqueia e brônquios principais. O seu correcto diagnóstico e tratamento constituem um território de interesse e preocupação para os profissionais de saúde, e requerem um profundo conhecimento da sua etiologia, fisiologia, diagnóstico e opções terapêuticas dado o potencial em originar significativa morbilidade e mortalidade. A avaliação da OVAC abrange múltiplas vertentes, entre as quais se salienta o componente clínico (sinais e sintomas), a repercussão fisiopatológica (função respiratória) e o estudo imagiológico (TC do tórax e broncoscopia). A compilação destes dados associada à etiologia, constituem factores importantes para estabelecer o prognóstico, determinar a necessidade de tratamento ou delinear uma futura intervenção terapêutica. A broncoscopia é o Gold Standard de avaliação desta condição, mas desde há cerca de 40 anos a curva de débito-volume constitui uma ferramenta não invasiva de detecção de OVAC. Apesar deste método ser utilizado até os nossos dias, poucos têm sido os estudos com o objectivo de verificar a sensibilidade e especificidade da curva de débito-volume na detecção de OVAC, bem como averiguar a relação entre as alterações morfológicas e quantitativas da mesma com a localização, o tipo e o grau da obstrução. Material e Métodos: Entre 1 de Novembro de 2009 e 30 de Abril de 2010, os doentes com indicação para a realização de broncoscopia diagnóstica ou terapêutica na Unidade de Técnicas Invasivas Pneumológicas (UTIP) do Centro Hospitalar Lisboa Norte – Hospital Pulido Valente (CHLN – HPV) foram seleccionados de forma consecutiva de acordo com os critérios de inclusão e exclusão. As avaliações (broncoscopia, curva de débito-volume e avaliação da dispneia) realizaram-se com um intervalo de tempo máximo de sete dias. A broncoscopia flexível foi realizada segundo as normas da British Thoracic Society e as curvas de débito-volume segundo as normas da ATS/ERS TaskForce 2005. Para a avaliação da dispneia recorreu-se à escala de dispneia MRC (Medical Research Council). Um painel de peritos realizou a avaliação da morfologia da curva de débito-volume (sugestiva ou não de OVAC) e um elemento independente a verificação dos critérios quantitativos e morfológicos (variáveis intra e extratorácica e fixa) da curva. O estudo foi aprovado pela Comissão de Ética para a Saúde do CHLN e todos os doentes assinaram um consentimento informado de participação. Resultados: Estudaram-se 82 doentes, 36 (44%) dos quais com OVAC. A predominância foi do género masculino, em relação ao feminino. A sensibilidade e especificidade dos critérios quantitativos da curva de débito-volume na detecção de OVAC foi de 91.3% e 88.9% respectivamente. Quando se utilizaram os critérios morfológicos da curva de débito-volume os valores foram de 93.5% e 30.6%. A agregação dos critérios morfológicos e quantitativos permitiu alcançar uma sensibilidade de 95.7% e especificidade de 86.1%. Nesta amostra, o critério quantitativo com maior ocorrência foi o FEF50/FIF50≥1 (83% dos doentes com OVAC). Este mostrou relacionar-se com todas as localizações de obstrução excepto o terço médio da traqueia. Mostrou, ainda, ter uma relação forte e positiva com o grau e tipo de obstrução (intra e extraluminal). O segundo foi o FEV1/PEF≥8, presente em 36% dos casos de OVAC. Relacionou-se com as obstruções no terço inferior da traqueia e brônquio principal direito (BPD). Também apresentou relação forte e positiva com o grau de obstrução e com os tipos de obstrução anteriormente descritos. Quanto à sintomatologia foi possível associar o grau de obstrução com o de dispneia e a presença de estridor com o grau e localização da obstrução na traqueia. Conclusões: Os resultados deste estudo demonstram que os critérios quantitativos da curva de débito-volume têm elevada sensibilidade e especificidade na detecção de OVAC. O critério FEV50/FIF50≥1 tem um bom poder discriminativo na detecção dessa condição, tendo sido relacionado com a localização, o grau e o tipo de obstrução. O critério FEV1/PEF≥8, embora com menor poder discriminativo, também se relaciona com o grau, a localização e o tipo de obstrução. A morfologia da curva tem uma boa sensibilidade mas baixa especificidade na detecção de OVAC, mas a agregação entre os critérios morfológicos e quantitativos aumenta a sensibilidade e especificidade. A dispneia e o estridor foram relacionados com o grau de obstrução e o último com a localização ao nível da traqueia.-------------ABSTRACT: Introduction: Central airway obstruction (CAO) refers to a pathological process that leads to restriction of airflow at the level of the glottis and subglottis, trachea and main bronchi. It’s proper diagnosis and treatment is an area of interest and concern to health professionals, and requires a deep knowledge of its etiology, physiology, diagnosis and treatment options, concerning the potential to cause significant morbidity and mortality. The evaluation of CAO covers multiple aspects: the clinical component (signs and symptoms), the pathophysiological effect (lung function) and the imaging study (bronchoscopy and chest CT). The compilation of this data associated with the etiology, are important for establishing prognosis, determine the need for treatment or outline a future therapeutic intervention. Bronchoscopy is the gold standard for evaluating this condition, but for the last 40 years the flow-volume loop has been used as a noninvasive tool for detecting CAO. Although this method is still in use, only few studies were made in order to verify its sensitivity and specificity in detecting CAO, and investigate the relation between morphological and quantitative changes of the curve to location, type and degree of obstruction. Methods: Between 1st November 2009 and 30th April 2010, patients with indication to perform diagnostic or therapeutic bronchoscopy in Interventional Pulmonology Unit - Hospital Pulido Valente (CHLN - HPV), were selected consecutively according to the inclusion and exclusion criteria. All assessments (bronchoscopy, flow-volume loop and dyspnea) were carried out within a period of seven days. The flexible bronchoscopy was performed according to the standards of the British Thoracic Society and the flow-volume loops in accordance with the standards of the ATS / ERS Taskforce 2005. For the evaluation of dyspnea was used to MRC dyspnea scale (Medical Research Council). A panel of experts evaluated the morphology of flow-volume loop (suggestive or non-suggestive of CAO) and an independent element established the quantitative criteria and morphological (intra and extrathoracic variables and fixed) of the curve. This study was approved by the Ethics Committee for Health CHLN and all the patients signed an informed consent to participate. Results: We’ve studied 82 patients, 36 (44%) of those with CAO. The majority of the patients were males, compared to females. The sensitivity and specificity of the quantitative criteria of the flow-volume curve in detecting CAO was 91.3% and 88.9% respectively. When we used the morphological criteria of flow-volume loop these values were 93.5% and 30.6%. The combination of quantitative and morphological criteria produced values of 95.7% sensitivity and 86.1% specificity. FEF50/FIF50≥1 was the most representative quantitative criterion (83% of patients with CAO) and it was correlated with all sites of obstruction except in the middle third of the trachea. It has shown a strong and positive association with the degree and type of obstruction (intra and extraluminal). The second was the FEV1/PEF ≥ 8, present in 36% of cases of CAO. It could be correlated with the obstruction in the lower third of the trachea and right main bronchus. It also showed a strong positive relation with the degree and types of obstruction described above. Regarding symptoms, we found a link between the degree of obstruction and dyspnea. The presence of stridor was correlated with the location and the degree of obstruction in the trachea. Conclusion: The results of this study demonstrate that the quantitative criteria of the flow-volume loop have a high sensitivity and specificity in detecting CAO. The criterion FEV50/FIF50 ≥ 1 has a good discriminative power to detect this condition and was related to the location, degree and type of obstruction. The criterion FEV1/PEF ≥ 8, although with a weaker discriminative power, also relates to the degree, location and type of obstruction. The morphology of the curve has a good sensitivity but low specificity in detecting CAO although the combination between the morphological and quantitative criteria increases sensitivity and specificity. Dyspnea and stridor were related to the degree of obstruction and the last one with its location in the trachea.

Modulation of electrical stimulation applied to human physiology and clinical diagnostic

The use, manipulation and application of electrical currents, as a controlled interference mechanism in the human body system, is currently a strong source of motivation to researchers in areas such as clinical, sports, neuroscience, amongst others. In electrical stimulation (ES), the current applied to tissue is traditionally controlled concerning stimulation amplitude, frequency and pulse-width. The main drawbacks of the transcutaneous ES are the rapid fatigue induction and the high discomfort induced by the non-selective activation of nervous fibers. There are, however, electrophysiological parameters whose response, like the response to different stimulation waveforms, polarity or a personalized charge control, is still unknown. The study of the following questions is of great importance: What is the physiological effect of the electric pulse parametrization concerning charge, waveform and polarity? Does the effect change with the clinical condition of the subjects? The parametrization influence on muscle recruitment can retard fatigue onset? Can parametrization enable fiber selectivity, optimizing the motor fibers recruitment rather than the nervous fibers, reducing contraction discomfort? Current hardware solutions lack flexibility at the level of stimulation control and physiological response assessment. To answer these questions, a miniaturized, portable and wireless controlled device with ES functions and full integration with a generic biosignals acquisition platform has been created. Hardware was also developed to provide complete freedom for controlling the applied current with respect to the waveform, polarity, frequency, amplitude, pulse-width and duration. The impact of the methodologies developed is successfully applied and evaluated in the contexts of fundamental electrophysiology, psycho-motor rehabilitation and neuromuscular disorders diagnosis. This PhD project was carried out in the Physics Department of Faculty of Sciences and Technology (FCT-UNL), in straight collaboration with PLUX - Wireless Biosignals S.A. company and co-funded by the Foundation for Science and Technology.

Management consulting labs-Galp loyalty

The objective of this consulting project was to assist Galp Energia in its approach to loyalty. In order to do so, two hypotheses were defined. The first assumed there was value to capture in the existing approach. The second held that it was possible to create value through a radically innovative approach. The methodology used to corroborate those hypotheses encompassed several quantitative analyses, as well as desk research and market research. As a result, a compilation of recommendations comprising implementation proposals that considered both hypotheses as valid was presented in order to suggest a paradigm change

Quadrature generators based on ring oscillators and shift registers

Quadrature oscillators are key elements in modern radio frequency (RF) transceivers and very useful nowadays in wireless communications, since they can provide: low quadrature error, low phase-noise, and wide tuning range (useful to cover several bands). RC oscillators can be fully integrated without the need of external components (external high Q-inductors), optimizing area, cost, and power consumption. The conventional structure of ring oscillator offers poor frequency stability and phasenoise, low quality factor (Q), and besides being vulnerable to process, voltage and temperature (PVT) variations, its performance degrades as the frequency of operation increases. This thesis is devoted to quadrature oscillators and presents a detailed comparative study of ring oscillator and shift register (SR) approaches. It is shown that in SRs both phase-noise and phase error are reduced, while ring oscillators have the advantage of occupying less area and less consumption due to the reduced number of components in the circuit. Thus, although ring oscillators are more suitable for biomedical applications, SRs are more appropriate for wireless applications, especially when specification requirements are more stringent and demanding. The first architecture studied consists in a simple CMOS ring oscillator employing an odd number of static single-ended inverters as delay cells. Subsequently, the quadrature 4-stage ring oscillator concept is shown and post-layout simulations are presented. The 3 and 4-phase single-frequency local oscillator (LO) generators employing SRs are presented, the latter with 50% and 25% duty-cycles. The circuits operate at 600 MHz and 900 MHz, and were designed in a 130 nm standard CMOS technology with a voltage supply of 1.2 V.

Optimization of wastewater quality in the Sines refinery

In order to address and resolve the wastewater contamination problem of the Sines refinery with the main objective of optimizing the quality of this stream and reducing the costs charged to the refinery, a dynamic mass balance was developed nd implemented for ammonia and polar oil and grease (O&G) contamination in the wastewater circuit. The inadequate routing of sour gas from the sour water stripping unit and the kerosene caustic washing unit, were identified respectively as the major source of ammonia and polar substances present in the industrial wastewater effluent. For the O&G content, a predictive model was developed for the kerosene caustic washing unit, following the Projection to Latent Structures (PLS) approach. Comparison between analytical data for ammonia and polar O&G concentrations in refinery wastewater originating from the Dissolved Air Flotation (DAF) effluent and the model predictions of the dynamic mass balance calculations are in a very good agreement and highlights the dominant impact of the identified streams for the wastewater contamination levels. The ammonia contamination problem was solved by rerouting the sour gas through an existing clogged line with ammonia salts due to a non-insulated line section, while for the O&G a dynamic mass balance was implemented as an online tool, which allows for prevision of possible contamination situations and taking the required preventive actions, and can also serve as a basis for establishing relationships between the O&G contamination in the refinery wastewater with the properties of the refined crude oils and the process operating conditions. The PLS model developed could be of great asset in both optimizing the existing and designing new refinery wastewater treatment units or reuse schemes. In order to find a possible treatment solution for the spent caustic problem, an on-site pilot plant experiments for NaOH recovery from the refinery kerosene caustic washing unit effluent using an alkaline-resistant nanofiltration (NF) polymeric membrane were performed in order to evaluate its applicability for treating these highly alkaline and contaminated streams. For a constant operating pressure and temperature and adequate operating conditions, 99.9% of oil and grease rejection and 97.7% of chemical oxygen demand (COD) rejection were observed. No noticeable membrane fouling or flux decrease were registered until a volume concentration factor of 3. These results allow for NF permeate reuse instead of fresh caustic and for significant reduction of the wastewater contamination, which can result in savings of 1.5 M€ per year at the current prices for the largest Portuguese oil refinery. The capital investments needed for implementation of the required NF membrane system are less than 10% of those associated with the traditional wet air oxidation solution of the spent caustic problem. The operating costs are very similar, but can be less than half if reusing the NF concentrate in refinery pH control applications. The payback period was estimated to be 1.1 years. Overall, the pilot plant experimental results obtained and the process economic evaluation data indicate a very competitive solution through the proposed NF treatment process, which represents a highly promising alternative to conventional and existing spent caustic treatment units.

New pteridophyte records for the territory of Amapá, Brazil.

Eighteen Pteridophyte taxa in 15 genera are reported as new for the Territory of Amapá, Brazil. The collections area a result of a recent Projeto Flora Amazônica/Programa Flora expedition to that region, and update previous lists of taxa for Amapá.In 1975, Tryon and Conant publised a checklist of the ferns of the Brazilian Amazônia reporting 84 taxa for the Territory of Amapá. The paucity of records for Amapá reflects, at least in part, the amount of botanical exploration. The most complete list of taxa occurring in the Territory is an unpublished list of collection compiled by J. M. Pires. This compilation reports 118 taxas for the Territory of Amapá. The following list is intended to update both the Pires compilation an the Tryon and Conant checklist for the Territor. These records are the result of a Projeto Flora Amazônica/Programa Flora expedition to the region in the latter part of 1979. Species were included in this list is not reportes in the compilation of colections for Amapá, or listed as specifically occurrin in Amapá in the monographs and revisions consulted for listed as specifically occurring in Amapá in the monograohs and revisions consulted for identification (Evans, 1969; Kramer, 1957, 1978; de la Sota, 1960; Lellinger, 1972; Maxon & Morton, 1938; Scamman, 1960, Smith, 1971; Tryon, 1941, 1964).This list reports 18 taxa in 15 genera, increasing the number of taxa in Amapá from the 118 listed by Pires to 136. Most of the taxa reported here might have been predicted to occur in Amapá on the basis of their distribution records for surrounding regions.Each species is followed by a collection number. The collection number is that of D. F. Austin, C. E. Nauman, R. S. Secco, C. Rosario, and M. R. Santos except for four collections in which R. S. Secco was absent and B. V. Rabelo was present, and these are indicated after the collection number. Specimens are deposited in the herbaria of the Museu Paraense Emílio Goeldi, Belém, Brazil and the United States. The family system is essentially that used by Tyron and Conant.

Cultural journalism in a digital environment : new models, practices and possibilities

Both culture coverage and digital journalism are contemporary phenomena that have undergone several transformations within a short period of time. Whenever the media enters a period of uncertainty such as the present one, there is an attempt to innovate in order to seek sustainability, skip the crisis or find a new public. This indicates that there are new trends to be understood and explored, i.e., how are media innovating in a digital environment? Not only does the professional debate about the future of journalism justify the need to explore the issue, but so do the academic approaches to cultural journalism. However, none of the studies so far have considered innovation as a motto or driver and tried to explain how the media are covering culture, achieving sustainability and engaging with the readers in a digital environment. This research examines how European media which specialize in culture or have an important cultural section are innovating in a digital environment. Specifically, we see how these innovation strategies are being taken in relation to the approach to culture and dominant cultural areas, editorial models, the use of digital tools for telling stories, overall brand positioning and extensions, engagement with the public and business models. We conducted a mixed methods study combining case studies of four media projects, which integrates qualitative web features and content analysis, with quantitative web content analysis. Two major general-interest journalistic brands which started as physical newspapers – The Guardian (London, UK) and Público (Lisbon, Portugal) – a magazine specialized in international affairs, culture and design – Monocle (London, UK) – and a native digital media project that was launched by a cultural organization – Notodo, by La Fábrica – were the four case studies chosen. Findings suggest, on one hand, that we are witnessing a paradigm shift in culture coverage in a digital environment, challenging traditional boundaries related to cultural themes and scope, angles, genres, content format and delivery, engagement and business models. Innovation in the four case studies lies especially along the product dimensions (format and content), brand positioning and process (business model and ways to engage with users). On the other hand, there are still perennial values that are crucial to innovation and sustainability, such as commitment to journalism, consistency (to the reader, to brand extensions and to the advertiser), intelligent differentiation and the capability of knowing what innovation means and how it can be applied, since this thesis also confirms that one formula doesn´t suit all. Changing minds, exceeding cultural inertia and optimizing the memory of the websites, looking at them as living, organic bodies, which continuously interact with the readers in many different ways, and not as a closed collection of articles, are still the main challenges for some media.

Inventário e valorização do património arqueológico do concelho da Chamusca : da época Romana à época Moderna

O presente relatório resulta do estágio efetuado na Câmara Municipal da Chamusca. O mesmo teve como objetivo a realização de um inventário do património arqueológico do concelho da Chamusca, centrado nos períodos da época Romana à Moderna, elaborando conjuntamente uma observação sobre o respetivo povoamento do território. O inventário realizado compilou toda a informação identificada nas fontes bibliográficas nos documentos da época já publicados e nas informações orais que se foram recolhendo. Posteriormente, procedeu-se à confirmação dos dados no terreno, através de uma prospeção dirigida aos sítios nos quais havia indícios de ocorrências patrimoniais. O desenvolvimento deste projeto e deste tipo de investigação possibilitou a identificação/relocalização de um número muito significativo de sítios e potenciais sítios arqueológicos, num total de 136 sítios. O seu inventário foi sistematizado e permitiu, assim, a compilação do conhecimento do património arqueológico deste município, contribuindo diretamente para a sua salvaguarda, preservação e valorização junto da comunidade. A autarquia passou agora a ter um instrumento essencial para a definição das políticas de salvaguarda do património, bem como para a definição das estratégias de desenvolvimento do seu território.

Access of WetAMD and DME patients to treatment in public hospitals

Degeneration (WetAMD) and Diabetic Macular Edema (DME) patients’ access to treatment in public hospitals, by identifying bottlenecks and stress points that prevent timely and adequate care to patients who suffer from a degenerative disease, and consequently for whom the lack of access to treatment can have disastrous consequences. Considering the specificity and degenerative traits of these conditions, the long queues for specialty appointments in public hospitals are a significant threat to patients’ health, as the disease may be misdiagnosed and or progress significantly, causing unnecessary permanent and non-reversible loss in visual acuity. Therefore optimizing the patient journey will increase patients’ access to adequate treatment, and prevent avoidable progress of a degenerative condition which causes permanent and non-reversible blindness. Following the investigation which supports this thesis, the patient journey was broken down into its different phases, so that key issues could be identified, and referred back to the main stress points highlighted during the interviews with physicians and administrators. Finally results were scrutinized and systematized, and a set of action points was proposed, considering what may cause major impact and is actually feasible to implement.

Artificial thymus: a tissue engineering strategy

The thymus is the central organ responsible for the generation of T lymphocytes (1). Various diseases cause the thymus to produce in- sufficient T cells, which can lead to immune-suppression (2). Since T cells are essential for the protection against pathogens, it is crucial to promote de novo differentiation of T cells on diseased individuals. The available clinical solutions are: 1) one protocol involving the transplant of thymic stroma from unrelated children only applicable for athymic children (3); 2) for patients with severe peripheral T cell depletion and reduced thymic activity, the administration of stimu- lating molecules stimulating the activity of the endogenous thymus (4). A scaffold (CellFoam) was suggested to support thymus regen- eration in vivo (5), although this research was discontinued. Herein, we propose an innovative strategy to generate a bioartificial thymus. We use a polycaprolactone nanofiber mesh (PCL-NFM) seeded and cultured with human thymic epithelial cells (hTECs). The cells were obtained from infant thymus collected during pediatric cardio-tho- racic surgeries. We report new data on the isolation and characterization of those cells and their interaction with PCL-NFM, by expanding hTECs into relevant numbers and by optimizing cell seeding methods.

An evolutionary multi-objective optimization system for earthworks

Earthworks involve the levelling or shaping of a target area through the moving or processing of the ground surface. Most construction projects require earthworks, which are heavily dependent on mechanical equipment (e.g., excavators, trucks and compactors). Often, earthworks are the most costly and time-consuming component of infrastructure constructions (e.g., road, railway and airports) and current pressure for higher productivity and safety highlights the need to optimize earthworks, which is a nontrivial task. Most previous attempts at tackling this problem focus on single-objective optimization of partial processes or aspects of earthworks, overlooking the advantages of a multi-objective and global optimization. This work describes a novel optimization system based on an evolutionary multi-objective approach, capable of globally optimizing several objectives simultaneously and dynamically. The proposed system views an earthwork construction as a production line, where the goal is to optimize resources under two crucial criteria (costs and duration) and focus the evolutionary search (non-dominated sorting genetic algorithm-II) on compaction allocation, using linear programming to distribute the remaining equipment (e.g., excavators). Several experiments were held using real-world data from a Portuguese construction site, showing that the proposed system is quite competitive when compared with current manual earthwork equipment allocation.

Portuguese strengths and fragilities on safety and health practices

Despite improvements over the years, accidents continue to be a scourge in the construction sector, leading to an increase in the number of journal articles addressing the issue, in an attempt to help construction industry to increase safety performance [1]. This paper aims to, helping construction industry and particulary tunneling community, describe the Portuguese approach to most typical health and safety problems in underground excavations performed with the Sequential Excavation Method (SEM). The article will address various topics, from safety management and organizational practices, to collective and personal protection equipment, to emergency planning. nt problems in safety and health matters are similar to several other countries, the paper will expose a compilation of Portuguese best practices used to solve that problems. This enunciation of best practices describes experience from most important and recognized Project Owners and Contractors in Portugal. In a second phase it will be analysed Portuguese weaknesses, identifying preventive measures, and their comparative importance, that should be adopted in Portugal in order to reduce accidents and health diseases.

A proactive intelligent decision support system for predicting the popularity of online news

"Lecture notes in computer science series, ISSN 0302-9743, vol. 9273"

Probing dispersion and re-agglomeration phenomena upon melt-mixing of polymer-functionalized graphite nanoplates

A one-step melt-mixing method is proposed to study dispersion and re-agglomeration phenomena of the as-received and functionalized graphite nanoplates in polypropylene melts. Graphite nanoplates were chemically modified via 1,3-dipolar cycloaddition of an azomethine ylide and then grafted with polypropylene-graft-maleic anhydride. The effect of surface functionalization on the dispersion kinetics, nanoparticle re-agglomeration and interface bonding with the polymer is investigated. Nanocomposites with 2 or 10 wt% of as-received and functionalized graphite nanoplates were prepared in a small-scale prototype mixer coupled to a capillary rheometer. Samples were collected along the flow axis and characterized by optical microscopy, scanning electron microscopy and electrical conductivity measurements. The as-received graphite nanoplates tend to re-agglomerate upon stress relaxation of the polymer melt. The covalent attachment of a polymer to the nanoparticle surface enhances the stability of dispersion, delaying the re-agglomeration. Surface modification also improves interfacial interactions and the resulting composites presented improved electrical conductivity.