Produção de matrizes porosas 3D baseadas em réplicas invertidas de cristais coloidais

A Engenharia de Tecidos surge da necessidade recorrente de regenerar ou recriar órgãos e tecidos danificados devido a vários tipos de trauma. A carência de funcionalidades resultante pode ser resolvida através da implantação de substitutos bio-sintéticos. O presente trabalho consiste na produção de matrizes porosas 3D baseadas em réplicas invertidas de cristais coloidais com futura aplicação em substituintes ósseos sintéticos para fraturas de não-união. O substituinte ósseo consiste numa estrutura denominada Inverse colloidal crystal (ICC), em que a sua organização singular resulta numa homogénea proliferação celular e num aumento das propriedades mecânicas, quando comparada com outros substituintes. O primeiro passo para a obtenção desta estrutura é a produção de microesferas de poliestireno, por uma técnica baseada em microfluídica. Posteriormente as microesferas são empacotadas resultando numa estrutura coesa com ligações entre microesferas vizinhas. O preenchimento dos espaços vazios entre microesferas pelo biomaterial pretendido e posterior remoção das microesferas dá origem à estrutura porosa do ICC. ICCs poliméricos (ϕCs = 1,00) e compósitos (ϕCs = 0,86 e ϕHA = 0,14; ϕCs = 0,67 e ϕHA = 0,33; ϕCs = ϕHA = 0,50) são produzidos e as suas propriedades mecânicas são testadas através de ensaios de compressão e comparadas com outros substituintes sintéticos. Para avaliação do comportamento dos materiais em contacto com meio biológico, foram realizados testes de citotoxicidade que revelaram uma viabilidade celular acima dos 80% em todos os ICCs.

Clinical and laboratory alterations in dogs naturally infected by Leishmania chagasi

INTRODUCTION: Canine visceral leishmaniasis (CVL) is a zoonotic disease with different clinical manifestations. Parasitism often occurs in bone marrow, but changes have been observed in peripheral blood and serum biochemical parameters. The aim of this study was to evaluate the hematological and biochemical parameters in dogs naturally infected by Leishmania chagasi. METHODS: Eighty-five adult dogs of both sexes and various weights and ages from the Zoonosis Control Center of Fortaleza (CCZ) were used, selected by immunofluorescence assay (IFA) and considered positive with IFA titers greater than 1:40 and by visualizing amastigotes of Leishmania chagasi in smears obtained by bone marrow aspiration. The dogs (n = 85) were grouped according to clinical signs: negative (CN = 7), subclinical (CS = 10), and clinical (CC = 68). Blood samples were collected for determination of hematological and biochemical serum values. The experimental protocol was approved by the CEUA/UECE. RESULTS: The most frequent clinical signs were cachexia (77.9%), keratitis (61.8%), and lymphadenopathy (55.9%), and 86.8% of the animals showed more than one clinical sign characteristic of CVL. In CC were observed reductions in red blood cells (63%), hematocrit (72%), and hemoglobin (62%), as well as leukocytosis (33%), neutropenia (28%), thrombocytopenia (50%), uremia (45%), hyperproteinemia (53%, p<0.05), hypergammaglobulinemia (62%, p<0.01), and hypoalbuminemia (58%). CONCLUSIONS: Animals with the clinical form of the disease demonstrate hematological and biochemical changes consistent with anemia, uremia, hyperproteinemia, and hyperglobulinemia, which present themselves as strong clinical markers of visceral leishmaniasis associated with the signs previously reported.

Measuring the impact of short and lending practices using the DGTW benchmarks

Mutual fund managers increasingly lend their holdings and/or use short sales to generate higher returns for their funds. This project presents a first look into the impact these practices on performance using the performance measures: i) Characteristic Selectivity (CS), the ability of the fund's managers to choose stocks that outperform their benchmarks; ii) Characteristic Timing (CT), the ability of the manager to time the market; iii) and Average Style (AS), the returns from funds systematically holding stocks with certain characteristics. These returns are computed through the DGTW benchmarks. The effect of other variables that have also been shown to impact fund’s returns – total net assets under management, investment styles, turnover and expense ratios – will also be analyzed. I find that managers who use short-sales do not exhibit better stock picking abilities than those who do not, while mutual funds that lend do present higher CS returns. In addition, while lending is not significant for the total performance of a fund, the employment of short-sales and of both short-sales and lending has a negative impact on the fund’s performance.

Fluconazole and amphotericin-B resistance are associated with increased catalase and superoxide dismutase activity in Candida albicans and Candida dubliniensis

Introduction Candida dubliniensis, a new species of Candida that has been recovered from several sites in healthy people, has been associated with recurrent episodes of oral candidiasis in AIDS and HIV-positive patients. This species is closely related to C. albicans. The enzymatic activity of C. dubliniensis in response to oxidative stress is of interest for the development of drugs to combat C. dubliniensis. Methods Fluconazole- and amphotericin B-resistant strains were generated as described by Fekete-Forgács et al. (2000). Superoxide dismutase (SOD) and catalase assays were performed as described by McCord and Fridovich (1969) and Aebi (1984), respectively. Results We demonstrated that superoxide dismutase (SOD) and catalase activities were significantly higher (p<0.05) in the fluconazole- and amphotericin B-resistant strains of C. dubliniensis and C. albicans than in the sensitive strains. The catalase and SOD activities were also significantly (p<0.01) higher in the sensitive and resistant C. albicans strains than in the respective C. dubliniensis strains. Conclusions These data suggest that C. albicans is better protected from oxidative stress than C. dubliniensis and that fluconazole, like amphotericin B, can induce oxidative stress in Candida; oxidative stress induces an adaptive response that results in a coordinated increase in catalase and SOD activities.

AS COSTUREIRAS, AS QUEENS E OS SEUS MANTOS: DESTERRITORIALIZAÇÃO, CULTURA MATERIAL E CONSTRUÇÃO DO LUGAR

Durante as décadas de 1980 e de 1990 a noção de lugar foi, na literatura antropológica, sujeita a uma abordagem crítica que debateu as dimensões metodológicas e conceptuais envolvidas na sua construção. No seguimento dessa abordagem, surgiram propostas de trabalho que, de maneiras muito diversas, conseguiram ultrapassar as limitações das concepções mais clássicas da figura do lugar. Essas propostas revelaram, no entanto, que mesmo quando estamos face a uma lógica de desterritorialização, a figura do lugar pode reaparecer (embora obviamente transmutada, visto construir-se no interior de outras lógicas sociais, culturais e económicas). Partindo de uma etnografia realizada na Ilha do Pico, o texto explora algumas das inovações, provenientes dos EUA no início do século XX, que foram introduzidas nas Festas do Espírito Santo. A principal inovação prende-se com a emergência de novos personagens: as rainhas (“queens”) coroadas durante o ritual, seguidas pelas costureiras indispensáveis à confecção dos seus vestidos e mantos. Centrado nos processos de feitura dos mantos, o texto pretende mostrar como a cultura material local se constrói e se transforma no interior de um movimento transcontinental constante de pessoas, rituais, coisas e técnicas. Num contexto transnacional, a mobilidade das pessoas pode objetificar-se em coisas que são feitas localmente, participando assim a desterritorialização na construção do lugar.

Identificação das fontes de contaminação fecal nas águas superficiais do Rio Tejo

As águas são potenciais vias de infeção, pois servem como veículos para disseminação de possíveis microrganismos patogénicos que podem levar a surtos. Por isso é importante manter os ambientes aquáticos livres de microrganismos. Para isso é necessário a constante monitorização desses ambientes. Isto é realizado através da utilização de microrganismos indicadores (FIB), que sugerem o nível de poluição fecal da água. Porém, tem sido demonstrado que os FIB possuem graves falhas na identificação de certos tipos de microrganismos, como por exemplo, os vírus, assim como na identificação da fonte de contaminação fecal. A partir disso surgiu o Microbial Source Tracking (MST), que tem como objetivo principal a identificação específica do hospedeiro ou ambiente causador da contaminação fecal. Neste estudo foram utilizadas uma combinação de diferentes métodos, sendo a maioria destas técnicas moleculares, para fornecer uma nova abordagem prática, viável e integrável a partir da utilização das amostras ambientais retiradas do Rio Tejo. Para isso foram efetuadas colheitas totalizando 73 amostras em quatro pontos diferentes no rio Tejo: VFX, MPN, ALC e Belém. Nestes pontos foram analisados quantitativamente os marcadores bacteriológicos E. coli e EF; os considerados potenciais indicadores de vírus, CS e Bacteriófagos de GB-124 e marcadores moleculares HAdV, mtDNA humano, bovino, suíno e de aves de consumo humano. Foram encontradas positividades para todos os pontos, com 99% para E. coli, 97% para EF, 99% para CS, 1% para Bacteriófagos de GB-124, 40% para HAdV, 90% para mtDNA humano, 92% mtDNA bovino, 58% mtDNA suíno, 37% mtDNA de aves de consumo humano. Estes marcadores foram também correlacionados, e devido à fraca correlação encontrada, os resultados indicam que as informações fornecidas pelos indicadores bacteriológicos e CS são diferentes das informações obtidas pelos indicadores moleculares.

Wideband CMOS low noise amplifiers

Modern fully integrated receiver architectures, require inductorless circuits to achieve their potential low area, low cost, and low power. The low noise amplifier (LNA), which is a key block in such receivers, is investigated in this thesis. LNAs can be either narrowband or wideband. Narrowband LNAs use inductors and have very low noise figure, but they occupy a large area and require a technology with RF options to obtain inductors with high Q. Recently, wideband LNAs with noise and distortion cancelling, with passive loads have been proposed, which can have low NF, but have high power consumption. In this thesis the main goal is to obtain a very low area, low power, and low-cost wideband LNA. First, it is investigated a balun LNA with noise and distortion cancelling with active loads to boost the gain and reduce the noise figure (NF). The circuit is based on a conventional balun LNA with noise and distortion cancellation, using the combination of a common-gate (CG) stage and common-source (CS) stage. Simulation and measurements results, with a 130 nm CMOS technology, show that the gain is enhanced by about 3 dB and the NF is reduced by at least 0.5 dB, with a negligible impact on the circuit linearity (IIP3 is about 0 dBm). The total power dissipation is only 4.8 mW, and the active area is less than 50 x 50 m2 . It is also investigated a balun LNA in which the gain is boosted by using a double feedback structure.We propose to replace the load resistors by active loads, which can be used to implement local feedback loops (in the CG and CS stages). This will boost the gain and reduce the noise figure (NF). Simulation results, with the same 130 nm CMOS technology as above, show that the gain is 24 dB and NF is less than 2.7 dB. The total power dissipation is only 5.4 mW (since no extra blocks are required), leading to a figure-of-merit (FoM) of 3.8 mW

Património Cultural Imaterial, Festa e Comunidade

A presente contribuição toma como ponto de partida a centralidade do conceito de comunidade nas políticas de Património Cultural Imaterial contemporâneas. Tendo como referência a minha pesquisa sobre festas do Espírito Santo (ou festas do Divino) nos Açores, na América do Norte e no Brasil, em particular – no caso do Brasil – em São Luís (Maranhão) defenderei três ideias e deixarei uma interrogação. A primeira ideia é que a festa não pode ser entendida sem ideias sobre comunidade, mesmo que coloquemos algumas aspas e especificações em “comunidade”. A segunda é que essas ideias, embora importantes, são insuficientes para dar conta das dinâmicas investidas na festa. De facto, para além de ideias sobre comunidade, a festa mobiliza e depende de um conjunto de outras agencialidades – de pessoas, redes de pessoas e especialistas rituais – que não podem ser subsumidas por ideias de comunidade. Partindo desta segunda ideia, proporei uma terceira ideia, assente numa reavaliação mais realista da importância que na festa têm ideias sobre comunidade. Quanto à interrogação é esta: será que abordar a festa por referência exclusiva aos agentes humanos – pessoas, redes de pessoas, comunidades, etc. – não deixa de lado aspectos importantes da festa? Sendo menos relevante para muitas festas “secularizadas”, esta interrogação é vital para festas com uma motivação e um conteúdo religiosos.

Stromal vascular fraction cell sheets angiogenic potential for tissue engineering and regenerative medicine applications

One of the biggest concerns in the Tissue Engineering field is the correct vascularization of engineered constructs. Strategies involving the use of endothelial cells are promising but adequate cell sourcing and neo-vessels stability are enduring challenges. In this work, we propose the hypoxic pre-conditioning of the stromal vascular fraction (SVF) of human adipose tissue to obtain highly angiogenic cell sheets (CS). For that, SVF was isolated after enzymatic dissociation of adipose tissue and cultured until CS formation in normoxic (pO2=21%) and hypoxic (pO2=5%) conditions for 5 and 8 days, in basal medium. Immunocytochemistry against CD31 and CD146 revealed the presence of highly branched capillary-like structures, which were far more complex for hypoxia. ELISA quantification showed increased VEGF and TIMP-1 secretion in hypoxia for 8 days of culture. In a Matrigel assay, the formation of capillary-like structures by endothelial cells was more prominent when cultured in conditioned medium recovered from the cultures in hypoxia. The same conditioned medium increased the migration of adipose stromal cells in a scratch assay, when compared with the medium from normoxia. Histological analysis after implantation of 8 days normoxic- and hypoxic-conditioned SVF CS in a hindlimb ischemia murine model showed improved formation of neo-blood vessels. Furthermore, Laser Doppler results demonstrated that the blood perfusion of the injured limb after 30 days was enhanced for the hypoxic CS group. Overall, these results suggest that SVF CS created under hypoxia can be used as functional vascularization units for tissue engineering and regenerative medicine.

Cryopreservation of Cell Sheets of Adipose Stem Cells: Limitations and Successes

Cell Sheets of hASCs (hASCs-CS) have been previously proposed for wound healing applications(1, 2) and despite the concern for production time reduction, the possibility of having these hASCs-CS off-the-shelf is appealing. The goal of this work was to define a cryopreservation methodology allowing to preserve cells viability and the properties CS matrix. hASCs-CS obtained from three different donors were created in UP-cell thermoresponsive dishes(Nunc, Germany) as previously reported(1,2). Different cryopreservation conditions were considered: i)FBS plus DMSO(5% and10%); ii)0.4M of Trehalose plus DMSO (5% and 10%); iii)cryosolution PLL (Akron Biotech, USA); and iv)vitrification. The cryopreservation effect was first assessed for cellular viability by flow cytometry using 7-AAD, and after dissociating the hASCs-CS with collagenase and trypsin-EDTA 0.25%. The expression (RT-PCR) and deposition (western blot and immunocytochemistry) of collagen type I, laminin and fibronectin, and the organization (TEM) of the extracellular matrix was further assessed before and after hASCs-CS cryopreservation to determine a potential effect of the method over matrix composition and integrity. The obtained results confirmed that cell viability is affected by the cryopreservation methodology, as shown before for different CS(3). Interestingly, the matrix properties were not significantly altered and the typical cell sheetâ s easiness of manipulation for transplantation was not lost.

Skin-derived cell-sheets as powerful tools to engineer skin analogues

Cell/cell-extracellular matrix (ECM) dynamic interactions appear to have a major role in regulating communication through soluble signaling, directing cell binding and activating substrates that participate in the highly organized wound healing process. Moreover, these interactions are also crucial for in vitro mimicking cutaneous physiology. Herein we explore cell sheet (CS) engineering to create cellular constructs formed by keratinocytes (hKC), fibroblasts (hDFB) and dermal microvascular endothelial cells (hDMEC), to target skin wound healing but also the in vitro recreation of relevant models. Taking advantage of temperature-responsive culture surfaces, which allow harvesting cultured cells as intact sheets along with the deposited native ECM, varied combinations of homotypic and heterotypic three-dimensional (3-D) CS-based constructs were developed. Constructs combining one CS of keratinocytes as an epidermis-like layer plus a vascularized dermis composed by hDFB and hDMECs were assembled as skin analogues for advancing in vitro testing. Simultaneously both hKC and hDMEC were shown to significantly contribute to the re-epithelialization of full-thickness mice skin wounds by promoting an early epithelial coverage, while hDMEC significantly lead to increased vessels density, incorporating the neovasculature. Thus, although determined by the cellular nature of the constructs, these outcomes demonstrated that CS engineering appear as an unique technology that open the possibility to create numerous combinations of 3D constructs to target defective wound healing as well as the construction of in vitro models to further mimic cutaneous functions crucial for drug screening and cosmetic testing assays.

Three-phase current-source shunt active power filter with solar photovoltaic grid interface

This paper presents the proposal of a three phase current source shunt active power filter (CS-SAPF) with photovoltaic grid interface. The proposed system combines the compensation of reactive power and harmonics with the injection of energy from a solar photovoltaic array into the electrical power grid. The proposed equipment presents the advantage of giving good use to the current source inverter, even when the solar photovoltaic array is not producing energy. The paper describes the control system of the CS SAPF, the energy injection control strategy, and the current harmonics and power factor compensation strategy. Simulation results to assess the performance of the proposed system are also presented.

Development of foam one-part geopolymers with enhanced thermal insulation performance and low carbon dioxide emissions

Buildings are responsible for more than 40% of the energy consumption and greenhouse gas emissions. Thus, increasing building energy efficiency is one the most cost-effective ways to reduce emissions. The use of thermal insulation materials could constitute the most effective way of reducing heat losses in buildings by minimising heat energy needs. These materials have a thermal conductivity factor, k (W/m.K) lower than 0.065 while other insulation materials such as aerated concrete can go up to 0.11. Current insulation materials are associated with negative impacts in terms of toxicity. Polystyrene, for example contains anti-oxidant additives and ignition retardants. In addition, its production involves the generation of benzene and chlorofluorocarbons. Polyurethane is obtained from isocyanates, which are widely known for their tragic association with the Bhopal disaster. Besides current insulation materials releases toxic fumes when subjected to fire. This paper presents experimental results on one-part geopolymers. It also includes global warming potential assessment and cost analysis. The results show that only the use of aluminium powder allows the production mixtures with a high compressive strength however its high cost means they are commercially useless when facing the competition of commercial cellular concrete. The results also show that one-part geopolymer mixtures based on 26%OPC +58.3%FA +8%CS +7.7%CH and 3.5% hydrogen peroxide constitute a promising cost efficient (67 euro/m3), thermal insulation solution for floor heating systems with low global warming potential of 443 KgCO2eq/m3.

Mecanismos de controle da variação sazonal da transpiração de uma floresta tropical no nordeste da amazônia

No presente trabalho foram estudadas a variação sazonal da transpiração, de uma floresta tropical, e sua dependência com fatores bióticos e abióticos. Utilizaram-se dados do projeto CARBOPARÁ, parte integrante do Experimento de Grande Escala da Biosfera-Atmosfera na Amazônia (LBA), coletados na reserva florestal de Caxiuanã, região nordeste da Amazônia. A evapotranspiração total num intervalo de 39 dias para o período chuvoso foi 108,2 mm, com valor médio de 2,9 mm dia-1, enquanto, durante o período menos chuvoso, a evapotranspiração total num intervalo de 29 dias foi 128,8 mm, com média de 4,3 mm dia-1 para o período. Os valores máximos da condutividade de superfície (Cs), nos dois períodos, ocorreram às 08:00 hl, sendo estes valores de 0,060 m s-1 e 0,045 m s-1 para o período chuvoso e menos chuvoso, respectivamente. A condutância aerodinâmica média (Ca) foi 0,164 m s-1 e 0,210 m s-1, para os períodos chuvoso e menos chuvoso, respectivamente. Os valores máximos da Ca observados para os períodos chuvoso e menos chuvoso foram, respectivamente, 0,220 e 0,375 m s-1. Verificou-se que Cs guarda uma relação exponencial inversa com o déficit de vapor de água atmosférico, para diferentes intervalos de irradiância solar global. A análise horária do fator de desacoplamento sugere que a evapotranspiração, durante a manhã, tem um maior controle realizado pela disponibilidade de energia, quando comparado ao período menos chuvoso. Durante a tarde verifica-se que o dossel da floresta progressivamente tende a estar mais acoplado à atmosfera, para ambos os períodos estudados, demonstrando maior controle superficial na transpiração.

Povoamento e paisagens no Vale Superior do Rio Terva, Boticas: projecto de investigação plurianual em arqueologia (PoPaTERVA 2013-2016): trabalhos arqueológicos no povoado das Batocas: relatório 2013-2014

O relatório que se apresenta respeita aos trabalhos arqueológicos desenvolvidos entre 2013 e 2014, inscritos no Projeto de Investigação Plurianual de Arqueologia (adiante PIPA) “Povoamento e Paisagens no Vale Superior do Rio Terva, Boticas – PoPaTERVA 2013-2016”, oportunamente aprovado pela Direção Geral do Património Cultural (DGPC: ofício n.º 2013/1 (169) CS: 875795 informação n.º 1704/DBC/2013). O projeto Povoamento e Paisagens no Vale Superior do Rio Terva, Boticas/ PoPaTERVA surge na sequência da conclusão do projeto de Conservação, Estudo, Valorização e Divulgação do Complexo Mineiro Antigo do Vale Superior do Rio Terva, Boticas, concebido em 2006 pela UAUM e executado entre 2010 e 2012 no âmbito de protocolo estabelecido com a Câmara Municipal de Boticas. Desta primeira ação de investigação resultou a classificação do Complexo Mineiro Antigo do Vale Superior do Rio Terva como Sítio de Interesse Público, promulgado pela Portaria n.º 386/2013 (DR, 2.º Série, n.º 115 de 18 de Junho de 2013 – ver Apêndice 7.1.2).