Novel photocatalyst-based colourimetric indicator for oxygen

The preparation and characterisation of a novel, UV-activated solvent-based, colourimetric indicator for O-2 is described, comprising a redox dye (methylene blue, MB), semiconductor photocatalyst (TiO2), and a sacrificial electron donor (SED), all dispersed/dissolved in a polymer medium (sulfonated polystyrene, SPS). Upon exposure, the indicator is readily photobleached as the MB is converted into its oxygen-sensitive, leuco form, LMB. Unlike its water-based counterpart, the recovery of the original colour is very slow (ca. 5 days cf. 6 min), probably due to the largely hydrophobic nature of the polymer encapsulation medium. The kinetics of film photobleaching appear to fit very well, in terms of: irradiance, [TiO2] and [MB], to the usual Langmuir-Hinshelwood type equation associated with a photocatalytic process. The glycerol appears not only to function as a SED, but also a plasticizer and medium for dye dissolution. The kinetics of colour recovery of the photobleached film appear directly dependent upon the ambient level of O-2 but shows a more complex dependence upon the relative humidity, RH. The photobleached film does not recover any of its colour over a 24 h period if the RH

How standardised patients award global scores in OSCEs: a qualitative study

Standardized patients (SPs) are often asked to award global scores on the humanistic aspects of a candidate’s performance in an OSCE. However, little is known about the process by which SPs arrive at their mark.
Five focus groups of SPs, using a convenience sample, were used to collect data until saturation. Thematic analysis was carried out independently by three researchers using a grounded theory approach.

Four major themes contributed to their decision-making process: environment, relationships within the exam, preparedness for the task and expectations of the student’s performance. Environmental factors included the station itself, the rating scale and examiner fatigue. Relationship factors included first impressions, the sense of purpose derived from examining and a tendency to mirror the examiner’s reaction. Factors relating to preparedness for task involved experience as an SP and technical aspects, such as the need for calibration. Lastly, expectations of performance were related to preconceptions about what makes a ‘good’ student, including their level of studies, appearance and technical performance.

In assessing students, SPs drew on their wider attitudes and experiences. SPs did not limit their assessment to humanistic traits but often included technical performance. Thus, SPs to some extent assessed a similar construct to examiners and this may help to explain the increased reliability associated with using SP scores. SP global scores are a useful adjunct but the process by which SPs award marks is complex and provides a challenge for training and standardisation.

Temporary tattoos:a novel OSCE assessment tool

Background: There are many issues regarding the use of real patients in objective structured clinical examinations (OSCEs). In dermatology OSCE stations, standardised patients (SPs) with clinical photographs are often used. Temporary transfer tattoos can potentially simulate skin lesions when applied to an SP. This study aims to appraise the use of temporary malignant melanoma tattoos within an OSCE framework. Method: Within an 11-station OSCE, a temporary malignant melanoma tattoo was developed and applied to SPs in a 'skin lesion' OSCE station. A questionnaire captured the opinions of the candidate, SP and examiners, and the degree of perceived realism of each station was determined. Standard post hoc OSCE analysis determined the psychometric reliability of the stations. Results: The response rates were 95.9 per cent of candidates and 100 per cent of the examiners and SPs. The 'skin lesion' station achieved the highest realism score compared with other stations: 89.0 per cent of candidates felt that the skin lesion appeared realistic; only 28 per cent of candidates had ever seen a melanoma before in training. The psychometric performance of the melanoma station was comparable with, and in many instances better than, other OSCE stations. Discussion: Transfer tattoo technology facilitates a realistic dermatology OSCE station encounter. Temporary tattoos, alongside trained SPs, provide an authentic, standardised and reliable experience, allowing the assessment of integrated dermatology clinical skills.

Solid phase synthesis of Smac/DIABLO-derived peptides using a 'Safety-Catch' resin:Identification of potent XIAP BIR3 antagonists

The N-terminal sequence of the Smac/DIABLO protein is known to be involved in binding to the BIR3 domain of the anti-apoptotic proteins IAPs, antagonizing their action. Short peptides and peptide mimetics based on the first 4-residues of Smac/DIABLO have been demonstrated to re-sensitize resistant cancer cells, over-expressing IAPs, to apoptosis. Based on the well-defined structural basis for this interaction, a small focused library of C-terminal capped Smac/DIABLO-derived peptides was designed in silico using docking to the XIAP BIR3 domain. The top-ranked computational hits were conveniently synthesized employing Solid Phase Synthesis (SPS) on an alkane sulfonamide 'Safety-Catch' resin. This novel approach afforded the rapid synthesis of the target peptide library with high flexibility for the introduction of various C-terminal amide-capping groups. The library members were obtained in high yield (>65%) and purity (>85%), upon nucleophilic release from the activated resin by treatment with various amine nucleophiles. In vitro caspase-9 activity reconstitution assays of the peptides in the presence of the recombinant BIR3-domain of human XIAP (500nM) revealed N-methylalanyl-tertiarybutylglycinyl-4-(R)-phenoxyprolyl-N-biphenylmethyl carboxamide (11a) to be the most potent XIAP BIR3 antagonist of the series synthesized inducing 93% recovery of caspase-9 activity, when used at 1µM concentration. Compound (11a) also demonstrated moderate cytotoxicity against the breast cancer cell lines MDA-MB-231 and MCF-7, compared to the Smac/DIABLO-derived wild-type peptide sequences that were totally inactive in the same cell lines.

The view from over there:reframing the OSCE through the experience of standardised patient raters

Ratings awarded by standardised patients (SPs) in UK objective structured clinical examinations (OSCEs) are typically based on humanistic (non-technical) skills and are complementary to clinician-examiner ratings. In psychometric terms, SP ratings appear to differ from examiner ratings and improve reliability. For the first time, we used qualitative methods from a constructivist perspective to explore SP experiences of rating, and consider how these impact our understanding of assessment.

Development and assessment of a robust optimization metric for WAMPAC modeling

A PMU based WAMS is to be placed on a weakly coupled section of distribution grid, with high levels of distributed generation. In anticipation of PMU data a Siemens PSS/E model of the electrical environment has been used to return similar data to that expected from the WAMS. This data is then used to create a metric that reflects optimization, control and protection in the region. System states are iterated through with the most desirable one returning the lowest optimization metric, this state is assessed against the one returned by PSS/E under normal circumstances. This paper investigates the circumstances that trigger SPS in the region, through varying generation between 0 and 110% and compromising the network through line loss under summer minimum and winter maximum conditions. It is found that the optimized state can generally tolerate an additional 2 MW of generation (3% of total) before encroaching the same thresholds and in one instance moves the triggering to 100% of generation output.

INFRARED SURFACE-PLASMONS ON PLATINUM SILICIDE

It is shown that surface plasmons (SPs) are supported on thin PtSi films. Using a prism-air gap-sample configuration, p-polarised infra-red light (3.39-mu-m) has been coupled with approximately 95% efficiency to SPs on the silicide electrode of PtSi-Si Schottky barrier structures. Stimulating SPs offers both a means of optically characterising silicide films and of enhancing optical absorption with a view to significantly increasing the Schottky barrier photoresponse.

Suspension plasma sprayed coatings using dilute hydrothermally produced titania feedstocks for photocatalytic applications

Titanium dioxide coatings have potential applications including photocatalysts for solar assisted hydrogen production, solar water disinfection and self-cleaning windows. Herein, we report the use of suspension plasma spraying (SPS) for the deposition of conformal titanium dioxide coatings. The process utilises a nanoparticle slurry of TiO2 (ca. 6 and 12 nm respectively) in water, which is fed into a high temperature plasma jet (ca. 7000-20 000 K). This facilitated the deposition of adherent coatings of nanostructured titanium dioxide with predominantly anatase crystal structure. In this study, suspensions of nano-titanium dioxide, made via continuous hydrothermal flow synthesis (CHFS), were used directly as a feedstock for the SPS process. Coatings were produced by varying the feedstock crystallite size, spray distance and plasma conditions. The coatings produced exhibited ca. 90-100% anatase phase content with the remainder being rutile (demonstrated by XRD). Phase distribution was homogenous throughout the coatings as determined by micro-Raman spectroscopy. The coatings had a granular surface, with a high specific surface area and consisted of densely packed agglomerates interspersed with some melted material. All of the coatings were shown to be photoactive by means of a sacrificial hydrogen evolution test under UV radiation and compared favourably with reported values for CVD coatings and compressed discs of P25.

Development of sialons colloidally processed in aqueous medium

Desenvolveu-se um novo método de processamento coloidal em meio aquoso para consolidar cerâmicos de α-Y-SiAlON, os quais foram sinterizados por prensagem isostática a quente (HIP) e por spark plasma sintering (SPS). Preparou-se com sucesso uma suspensão aquosa de pós precursores de YSiAlON (Si3N4, Al2O3, Y2O3 e AlN), temporariamente estável, usando Dolapix PC21 como dispersante, permitindo a fabricação de pós granulados pela técnica de aspersão-congelamento-liofilização e a consolidação de corpos em verde por enchimento por barbotina. Avaliou-se o efeito do excesso de oxigénio introduzido pelo processamento aquoso no desenvolvimento microestrutural e nas propriedades mecânicas. Os corpos de Y-SiAlON consolidados por enchimento por barbotina e sinterizados por HIP a 1800ºC apresentaram microestruturas e propriedades mecânicas similares a corpos consolidados por prensagem a seco. Estes materiais exibiram densificação completa, dureza Vickers máxima de 2003 e tenacidade à fractura (método SEVNB) máxima de 5.20 MPam1/2. Foi ainda possível estabelecer uma relação estreita entre o aumento do conteúdo em oxigénio das amostras sinterizadas e a diminuição da tenacidade à fractura. Na tentativa de melhorar a tenacidade à fractura dos materiais, procedeu-se à incorporação nas suspensões de sementes de Ca-α-SiAlON de geometria alongada produzidas por síntese por combustão, adicionadas como agentes de reforço. A síntese por combustão realizada em larga escala (cargas até 1 kg) não produziu efeitos negativos óbvios nos produtos da reacção. Investigara-se os efeitos da adição de 5 % em peso de sementes nas propriedades mecânicas e no desenvolvimento microestrutural de amostras densificadas por HIP. Em comparação com os materiais sem sementes, a tenacidade à fractura (método SEVNB) aumentou 13%, mas a dureza Vickers resultou 14,5% inferior. A sinterização por SPS permitiu obter densificação completa a temperaturas tão baixas como 1600ºC a partir dos pós granulados de Y-SiAlON sem a adição extra de Y2O3 para aumentar o teor de fase líquida. Os materiais sinterizados a 1700ºC e 1600ºC mostraram valores máximos de tenacidade à fractura de 4.36 e 4.20 MPam1/2 (método SEVNB), e de dureza Vickers de 2089 e 2084, respectivamente. Esta técnica de sinterização permitiu ainda obter corpos sinterizados translúcidos com uma transmitância máxima de 61% numa amostra de 2mm de espessura. Os corpos translúcidos apresentaram dureza Vickers de 2154 e tenacidade à fractura 3.74 MPam1/2 (método SEVNB).

Service building in dense service provider environments

Genericamente falando, os serviços sobre redes têm vindo a afastar-se de um modelo monolítico para um modelo de criação de serviços que permite ou - como é mais frequente - requer a cooperação entre vários Provedores de Serviço. A Internet, que tem vindo a forçar a convergência de serviços, mostra que começa a ser virtualmente impossível a um único operador fornecer qualquer serviço com um mínimo de interesse para os utilizadores. Esta tese foca-se em serviços de transporte (e.g., connectividade) e discute o impacto das fronteira que as ofertas de serviços têm com o negócio. A questão central é a seguinte: o que muda quando o mesmo serviço é oferecido não apenas por um mas por mais do que um Provedor de Serviço. Por um lado, esta tese cobre, em abs tracto, a noção de Provedor se Serviço, como evoluiu e em que sentido está a evoluir, particularmente num contexto de muitos Provedores de Serviço. Os primeiros capítulos desta tese analizam e propõem arquitecturas para cooperação inter-Provedor-de-Serviço e para serviços comuns tais como multimédia. Por outro lado, oferece-se soluções práticas, com as respectivas avaliações, para alguns problemas, que ainda hoje se mantêm em aberto, tais como encaminhamento inter-domínio, Qualidade-de-Serviço, Mobilidade e distribuição de conteúdos, tais como as contribuições relacionadas com o impacto da noção administrativa de Sistemas Autónomos sobre encaminhamento inter-domínio, uma arquitectura de transporte inter-domínio e o problema que levanta da ineficiência que decorre do planeamento não- cooperativo de Redes de Entrega de Conteúdos.

Thick-microstructures for MPGDs: simulations and experimental studies

Cherenkov Imaging counters require large photosensitive areas, capable of single photon detection, operating at stable high gains under radioactive backgrounds while standing high rates, providing a fast response and a good time resolution, and being insensitive to magnetic fields. The development of photon detectors based in Micro Pattern Gaseous detectors (MPGDs), represent a new generation of gaseous photon detectors. In particular, gaseous detectors based on stacked Thick-Gaseous Electron Multipliers (THGEMs), or THGEM based structures, coupled to a CsI photoconverter coating, seem to fulfil the requirements imposed by Cherenkov imaging counters. This work focus on the study of the THGEM-based detectors response as function of its geometrical parameters and applied voltages and electric fields, aiming a future upgrade of the Cherenkov Imaging counter RICH-1 of the COMPASS experiment at CERN SPS. Further studies to decrease the fraction of ions that reach the photocathode (Ion Back Flow – IBF) to minimize the ageing and maximize the photoelectron extraction are performed. Experimental studies are complemented with simulation results, also perfomed in this work.

Cultura suicida no Alentejo: os factores promotores de ideação suicida e desesperança

Dissertação de mest., Psicologia (Psicologia da Saúde), Faculdade de Ciências Humanas e Sociais, Univ. do Algarve, 2010

Controlled delivery of gentamicin using poly(3-hydroxybutyrate) microspheres

Poly(3-hydroxybutyrate), P(3HB), produced from Bacillus cereus SPV using a simple glucose feeding strategy was used to fabricate P(3HB) microspheres using a solid-in-oil-water (s/o/w) technique. For this study, several parameters such as polymer concentration, surfactant and stirring rates were varied in order to determine their effect on microsphere characteristics. The average size of the microspheres was in the range of 2 μm to 1.54 μm with specific surface areas varying between 9.60 m(2)/g and 6.05 m(2)/g. Low stirring speed of 300 rpm produced slightly larger microspheres when compared to the smaller microspheres produced when the stirring velocity was increased to 800 rpm. The surface morphology of the microspheres after solvent evaporation appeared smooth when observed under SEM. Gentamicin was encapsulated within these P(3HB) microspheres and the release kinetics from the microspheres exhibiting the highest encapsulation efficiency, which was 48%, was investigated. The in vitro release of gentamicin was bimodal, an initial burst release was observed followed by a diffusion mediated sustained release. Biodegradable P(3HB) microspheres developed in this research has shown high potential to be used in various biomedical applications.

Teor crítico de cloretos para iniciação da corrosão do aço no betão: influência do estado de superfície da armadura

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

O impacto (custo) das LMELT decorrente de acidentes de trabalho numa organização de saúde

RESUMO - A morbilidade associada às lesões músculoesqueléticas ligadas ao trabalho (LMELT) origina uma elevada perda de produtividade (absentismo e presentismo) em organizações de saúde, o que induz um substantivo impacto (custo) económico. Nesse contexto, os profissionais de saúde, como grupo vulnerável à ocorrência de LMELT, nomeadamente aqueles que mobilizam os doentes diariamente, apresentam elevadas taxas de acidentes de trabalho com absentismo. Considerando a importância do capital humano em saúde e tendo em conta o contexto actual de contenção da despesa no sector da saúde português, o despiste de situações de perda de produtividade e seu impacto económico em instituições de saúde, assume um papel fundamental na gestão dessas organizações. O presente estudo teve como objetivo avaliar o impacto (custo) das LMELT por acidente de trabalho em enfermeiros e assistentes operacionais do CMRA durante o período de 2009 a 2013. Partindo da identificação dos acidentes de trabalho (AT) ocorridos nestes grupos profissionais entre 2009 e 2013, da lesão musculoesquelética resultante e do absentismo registado os participantes no estudo responderam aos itens da escala WQL-8 e SPS-6, para se determinar também os níveis de presentismo. Este estudo adotou a metodologia do capital humano para estimar os custos indiretos ou perda de produtividade das LMELT. Constatou-se que são as transferências a maior causa das LMELT, com uma sintomatologia mais prevalente na região lombar. Existe perda de produtividade nesta instituição entre 2009 e 2013 com um custo total estimado em 222.015,98€, absentismo e presentismo, sendo a Distração Evitada a dimensão que apresenta maiores valores.