Light harvesting in solar cells using natural pigments from red fruits adsorbed to mesoporous TiO2

Nature has developed strategies to present us with a wide variety of colours, from the green of leaves to the bright colours seen in flowers. Anthocyanins are between these natural pigments that are responsible for the great diversity of colours seen in flowers and fruits. Anthocyanins have been used to sensitize titanium dioxide (TiO2) in Dye-Sensitized Solar Cells (DSSCs). DSSCs have become one of the most popular research topic in photovoltaic cells due to their low production costs when compared to other alternatives. DSSCs are inspired in what happens in nature during photosynthesis. A primary charge separation is achieved by means of a photoexcited dye capable of performing the electron injection into the conduction band of a wide band-gap semiconductor, usually TiO2. With this work we aimed to synthesize a novel mesoporous TiO2 structure as the semiconductor in order to increase the dye loading. We used natural occurring dyes such as anthocyanins and their synthetic flavylium relatives, as an alternative to the widely used metal complexes of Ru(II) which are expensive and are environmentally unsafe. This offers not only the chance to use safer dyes for DSSCs, but also to take profit of waste biological products, such as wine and olive oil production residues that are heavily loaded with anthocyanin dyes. We also performed a photodegradation study using TiO2 as the catalyst to degrade dye contaminants, such as those from the wine production waste, by photo-irradiation of the system in the visible region of the light spectrum. We were able to succeed in the synthesis of mesoporous TiO2 both powder and thin film, with a high capacity to load a large amount of dye. We proved the concept of photodegradation using TiO2 as catalyst. And finally, we show that wine production waste is a possible dye source to DSSCs application.

Fabrication and characterization of transparent conductive oxide surface sensors for electrocorticography – TrECoG

Understanding how the brain works has been one of the greatest goals of mankind. This desire fuels the scientific community to pursue novel techniques able to acquire the complex information produced by the brain at any given moment. The Electrocorticography (ECoG) is one of those techniques. By placing conductive electrodes over the dura, or directly over the cortex, and measuring the electric potential variation, one can acquire information regarding the activation of those areas. In this work, transparent ECoGs, (TrECoGs) are fabricated through thin film deposition of the Transparent Conductive Oxides (TCOs) Indium-Zinc-Oxide (IZO) and Gallium-Zinc-Oxide (GZO). Five distinct devices have been fabricated via shadow masking and photolithography. The data acquired and presented in this work validates the TrECoGs fabricated as efficient devices for recording brain activity. The best results were obtained for the GZO- based TrECoG, which presented an average impedance of 36 kΩ at 1 kHz for 500 μm diameter electrodes, a transmittance close to 90% for the visible spectrum and a clear capability to detect brain signal variations. The IZO based devices also presented high transmittance levels (90%), but with higher impedances, which ranged from 40 kΩ to 100 kΩ.

Life cycle of Trypanosoma cruzi (y strain) in mice

Since 1958, we have studied experimental Chagas' disease (CD) by subcutaneous inoculation of 1,000 blood forms of Trypanosoma cruzi (Y strain) in Balb/C. mice. Evolution of parasitemia remained constant, beginning on the 5th and 6th day of the disease, increasing progressively, achieving a maximum on about the 30th day. After another month, only a few forms were present, and they disappeared from the circulation after the third month, as determined from direct examination of slides and the use of a Neubauer Counting Chamber. These events coincided with the appearance of amastigote nests in the tissues (especially the cardiac ones), starting the first week, and following the Gauss parasitemia curve, but they were not in parallel until the chronic stage. In 1997, we began to note the following changes: Parasites appeared in the circulation during the first week and disappeared starting on the 7th day, and there was a coincident absence of the amastigote nests in the tissues. A careful study verified that young forms in the evolutionary cycle of T. cruzi (epi + amastigotes) began to appear alongside the trypomastigotes in the circulation on the 5th and 7th post-inoculation day. At the same time, rounded, oval, and spindle shapes were seen circulating through the capillaries and sinusoids of the tissues, principally of the hematopoietic organs. Stasis occurs because the diameter of the circulating parasites is greater than the vessels, and this makes them more visible. Examination of the sternal bone marrow revealed young cells with elongated forms and others truncated in the shape of a "C" occupying the internal surface of the blood cells that had empty central portions (erythrocytes?). We hypothesize that there could be a loss of virulence or mutation of the Y strain of Trypanosoma cruzi.

Reconfigurable photonic logic architecture

The amorphous silicon photo-sensor studied in this thesis, is a double pin structure (p(a-SiC:H)-i’(a-SiC:H)-n(a-SiC:H)-p(a-SiC:H)-i(a-Si:H)-n(a-Si:H)) sandwiched between two transparent contacts deposited over transparent glass thus with the possibility of illumination on both sides, responding to wave-lengths from the ultra-violet, visible to the near infrared range. The frontal il-lumination surface, glass side, is used for light signal inputs. Both surfaces are used for optical bias, which changes the dynamic characteristics of the photo-sensor resulting in different outputs for the same input. Experimental studies were made with the photo-sensor to evaluate its applicability in multiplexing and demultiplexing several data communication channels. The digital light sig-nal was defined to implement simple logical operations like the NOT, AND, OR, and complex like the XOR, MAJ, full-adder and memory effect. A pro-grammable pattern emission system was built and also those for the validation and recovery of the obtained signals. This photo-sensor has applications in op-tical communications with several wavelengths, as a wavelength detector and to execute directly logical operations over digital light input signals.

Al-doped ZnO ceramic sputtering targets based on nanocrystalline powders produced by emulsion detonation synthesis – deposition and application as a transparent conductive oxide material

Transparent conducting oxides (TCOs) have been largely used in the optoelectronic industry due to their singular combination of low electrical resistivity and high optical transmittance. They are usually deposited by magnetron sputtering systems being applied in several devices, specifically thin film solar cells (TFSCs). Sputtering targets are crucial components of the sputtering process, with many of the sputtered films properties dependent on the targets characteristics. The present thesis focuses on the development of high quality conductive Al-doped ZnO (AZO) ceramic sputtering targets based on nanostructured powders produced by emulsion detonation synthesis method (EDSM), and their application as a TCO. In this sense, the influence of several processing parameters was investigated from the targets raw-materials synthesis to the application of sputtered films in optoelectronic devices. The optimized manufactured AZO targets present a final density above 99 % with controlled grain size, an homogeneous microstructure with a well dispersed ZnAl2O4 spinel phase, and electrical resistivities of ~4 × 10-4 Ωcm independently on the Al-doping level among 0.5 and 2.0 wt. % Al2O3. Sintering conditions proved to have a great influence on the properties of the targets and their performance as a sputtering target. It was demonstrated that both deposition process and final properties of the films are related with the targets characteristics, which in turn depends on the initial powder properties. In parallel, the influence of several deposition parameters in the film´s properties sputtered from these targets was investigated. The sputtered AZO TCOs showed electrical properties at room temperature that are superior to simple oxides and comparable to a reference TCO – indium tin oxide (ITO), namely low electrical resistivity of 5.45 × 10-4 Ωcm, high carrier mobility (29.4 cm2V-1s-1), and high charge carrier concentration (3.97 × 1020 cm-3), and also average transmittance in the visible region > 80 %. These superior properties allowed their successful application in different optoelectronic devices.

Mechanisms underlying intracellular delivery

AuNPs are versatile systems used for different biomedical application including imaging, drug and gene delivery. These systems support the intracellular transport of active molecules, a step that is considered one of the crucial problems in drug delivery. Nevertheless, in order to design optimal multifunctional AuNPs for specific and efficient nanomedicine applications, the mechanism by which AuNPs interact with living cells must be fully understand. The main goal of this work consisted in the assessment of the cellular uptake mechanism of 14 nm spherical AuNPs by A549 cells, through fluorescent spectroscopy and microscopy, in combination with quantitative analysis by ICP-MS. TAMRA labeled AuNPs were characterized by UV-visible and fluorescent spectroscopy and the final hydrodynamic diameter of 22.5 ± 0.33 nm was obtained by DLS. Regarding the cellular uptake studies, the AuNPs presented a fast cellular uptake kinetics reaching a saturation point after 6 hours of incubation in A549 cells. Further investigation concerning the internalization mechanism of this AuNPs was evaluated using specific inhibitors for different endocytic pathways. Optimal inhibition was achieved using chlorpromazine, inhibitor of clathrin-mediated endocytosis, resulting in a 23.5 % inhibition of AuNPs after 1 hour of incubation. This preliminary result obtained by fluorescent spectroscopy suggests that these AuNPs were predominantly uptake by clathrin-mediated endocytosis, meaning that other endocytic pathways must be involved in the cellular uptake of this AuNPs. In what cell viability is concern, the prepared AuNPs and the endocytic inhibitors revealed no significant effect on the cell viability in A549 cell line.

Visions on high-speed trains: a methodological analysis

Based on the report for the unit “Foresight Analysis Methods” of the PhD program on Technology Assessment in 2013. This unit was supervised by Prof. António Moniz. The paper had meanwhile contributions from the supervisor and Dr. Douglas Robinson.

Going Public: Conservation of Contemporary Artworks. Between Backstage and Frontstage in Contemporary Art Museums

In museum studies and history of art, what happens behind the scenes of museums stays relatively unseen and unspoken about. In the arts, generally speaking, what is dismissed as irrelevant (e.g. the realm of practices) is deliberately detached from what is thought to really matter; theory, discourse, content and meaning. Up till recently, backstage activities such as conservation practices are merely discussed among specialists and museum professionals. Only the outcomes of these discussions are sometimes – if at all – explicitly communicated to a larger public. Studies into the practices of contemporary art conservation however show that practices behind the scenes play an important role in the perpetuation of these artworks. What happens behind the scenes in terms of conservation has, in several ways, important effects on the ongoing life of these artworks in a museum context. Conservation practices, I argue, should therefore become a necessary part of museum studies and history of art. How can the working practices of conservators become more visible and transparent to a diversity of audiences, including researchers? And what does this mean in terms of research methodology?

Decentralization and privatization in Portuguese health reforms

ABSTRACT - The Portuguese National Health Service (SNS), a universal, centralized and public owned health care system, exhibits an extraordinary record of equalization in the access to health care and health gains in the late thirty years. However, the most recent history of the Portuguese health reform is pervaded by the influence of decentralization and privatization. Decentralization has been present in the system design since the 1976 Constitution, at least in theory. Private ownership of health care suppliers and out-ofpocket expenditures, on the financing side, both have a long tradition of relevance in the NHS mix of services. The initial aim of this study was to demonstrate expected parallelism between health reforms and public administration reforms, where a common pattern of joint decentralization and privatization was observed in many countries. Observers would be tempted to consider these two movements as common signs of new public management (NPM) developments. They have common objectives, are established around the core concepts of gains in effectiveness, efficiency, equity and quality of public services, through improved accountability. However, in practice, in Portugal, each movement was developed in a totally separated way. Besides those rooted in the NPM theory, there are few visible signs of association between decentralization and privatization. Decentralization, in the Portuguese SNS, was never intended to be followed by a privatization movement; it was seen merely as a public administration tool. Private management of health services, as stated in the most recent SNS legislation, was never intended to have decentralization as a condition or as a consequence. Paradoxically, in the Portuguese context, it has led invariably to centralized control. While presented as separate instruments for a common purpose, the association between decentralization and privatization still lacks a convincing demonstration. Many common health care management stereotypes remain to be checked out if we want to look for eventual associations between these two organizational tools.

Assessment of a novel Cu (II) complex as a potential anticancer agent

Widely used in cancer treatment, chemotherapy still faces hindering challenges, ranging from severe induced toxicity to drug resistance acquisition. As means to overcome these setbacks, newly synthetized compounds have recently come into play with the basis of improved pharmacokinetic/pharmacodynamic properties. With this mind-set, this project aimed towards the antiproliferative potential characterization of a group of metallic compounds. Additionally the incorporation of the compounds within a nanoformulation and within new combination strategies with commercial chemotherapeutic drugs was also envisaged. Cell viability assays presented copper (II) compound (K4) as the most promising, presenting an IC50 of 6.10 μM and 19.09 μM for HCT116 and A549 cell line respectively. Exposure in fibroblasts revealed a 9.18 μM IC50. Hoechst staining assays further revealed the compound’s predisposition to induce chromatin condensation and nuclear fragmentation in HCT116 upon exposure to K4 which was later demonstrated by flow cytometry and annexin V-FITC/propidium iodide double staining analysis (under 50 % cell death induction). The compound further revealed the ability to interact with major macromolecules such as DNA (Kb = 2.17x105 M-1), inducing structural brakes and retardation, and further affecting cell cycle progression revealing delay in S-phase. Moreover BSA interactions were also visible however not conclusive. Proteome profiling revealed overexpression of proteins involved in metabolic activity and underexpression of proteins involved in apoptosis thus corroborating Hoechst and apoptosis flow cytometry data. K4 nanoformulation suffered from several hindrances and was ill succeeded in part due to K4’s poor solubility in aqueous buffers. Other approaches were considered in this regard. Combined chemotherapy assays revealed high cytotoxicity for afatinib and lapatinib strategies. Lapatinib and K4 proteome profiling further revealed high apoptosis rates, high metabolic activity and activation of redundant proteins as part of compensatory mechanisms.

Visões do Império : a 1ª EXposição Colonial de 1934 e alguns dos seus álbuns

A Primeira Exposição Colonial Portuguesa realizada no Porto em 1934 foi a consequência visível do impulso que Salazar quis dar à «política colonial» portuguesa e a uma orientação imperial em que colonizar e civilizar as populações indígenas eram as palavras de ordem. Como corolário da exposição foram produzidos, entre outros, dois importantes álbuns, hoje documentos de inegável interesse histórico, não só enquanto discurso de propaganda do regime do Estado Novo, mas também enquanto narrativas visuais ou “visões do Império”. São eles, o Álbum Fotográfico da autoria do fotógrafo Domingos Alvão e o Álbum Comemorativo, com reproduções de pinturas e desenhos do pintor Eduardo Malta. Neste trabalho pretendemos reflectir sobre essas “visões do Império”, pois elas expressam uma visualidade e um imaginário que se traduz em práticas sociais, em valores e em relações de dominação que definem uma política do olhar, onde o corpo se torna um espaço de inscrição, bem como de categorização racial e cultural. Em suma, é através dessas imagens que vemos as relações de poder e as formas de dominação sobre o outro, que impregnaram a exposição.

Chlorite Dismutase from perchlorate reducing bacteria. A potential biocatalyst to eliminate chlorinated species from polluted water resources and industrial wastes

Magnetospirillum (M.) sp. strain Lusitani, a perchlorate reducing bacteria (PRB), was previously isolated from a wastewater treatment plant and phylogenetic analysis was performed to classify the isolate. The DNA sequence of the genes responsible for perchlorate reduction and chlorite dismutation was determined and a model was designed based on the physiological roles of the proteins involved in the pcr-cld regulon. Chlorite dismutase (Cld) was purified from Magnetospirillum sp. strain Lusitani cells grown in anaerobiosis in the presence of perchlorate. The protein was purified up to electrophoretic grade using HPLC techniques as a 140 kDa homopentamer comprising five ~28 kDa monomers. Steady-state kinetic studies showed that the enzyme follows a Michaelis-Menten model with optimal pH and temperature of 6.0 and 5°C, respectively. The average values for the kinetic constants KM and Vmax were respectively 0.56 mM and 10.2 U, which correspond to a specific activity of 35470 U/mg and a turnover number of 16552 s-1. Cld from M. sp. strain Lusitani is inhibited by the product chloride, but not by dioxygen. Inhibition constants KiC= 460 mM and KiU= 480 mM indicated that sodium chloride is a weak mixed inhibitor of Cld, with a slightly stronger competitive character. The X-ray crystallography structure of M. sp. strain Lusitani Cld was solved at 3.0 Å resolution. In agreement with cofactor content biochemical analysis, the X-ray data showed that each Cld monomer harbors one heme b coordinated by a histidine residue (His188), hydrogen-bonded to a conserved glutamic acid residue (Glu238). The conserved neighboring arginine residue (Arg201) important for substrate positioning, was found in two different conformations in different monomers depending on the presence of the exogenous ligand thiocyanate. UV-Visible and CW-EPR spectroscopies were used to study the effect of redox agents, pH and exogenous ligands on the heme environment.

As Comissões Parlamentares de Inquérito no Portugal democrático, 1976-2015

As transformações operadas no mundo contemporâneo, em especial no que respeita às estruturas do poder, à sua maior autonomização e diferenciação, tiveram particulares reflexos ao nível dos Parlamentos e das funções que prosseguem. Desde a sua origem, no passado século XIII, à atualidade, grandes acontecimentos, clivagens e factos históricos estão presentes na sua linha evolutiva. A democratização do regime parlamentar e a legitimidade outorgada através de eleições democráticas e concorrenciais são um marco ímpar na sua história. A complexidade das sociedades hodiernas catapultou o Poder Executivo em detrimento do Parlamento, enquanto órgão legislativo por excelência. Tal circunstancialismo levou, não ao proclamado declínio dos Parlamentos, mas a reformas estruturantes. Outras e mais importantes funções seriam prosseguidas. Se as iniciativas legislativas e a definição das políticas públicas passaram a ser quase um exclusivo do Governo, havia que desenvolver e ampliar, por parte dos Parlamentos, os instrumentos de controlo, fiscalização e escrutínio da ação governativa. Entre os clássicos instrumentos de controlo avulta o Inquérito Parlamentar, materializado em Comissões Parlamentares de Inquérito, dotadas de poderes especiais para recolha de informação e para investigação. No seu percurso parlamentar, também as Comissões de Inquérito foram sendo alvo de constantes aperfeiçoamentos, de ordem constitucional, legal e regimental. A excessiva partidarização da atividade parlamentar de outrora e sobretudo a confusão entre o governo e o partido que o sustentava a nível parlamentar, o confronto desequilibrado de meios entre as maiorias e as minorias, levaram a um reposicionamento do inquérito parlamentar enquanto garante do direito das minorias. Não sendo expectável que as grandes iniciativas de controlo sejam tomadas pelo partido maioritário, cabe à oposição esse papel. Em Portugal, diminuta era a tradição do instituto do inquérito parlamentar, razão porque foi efémera e sem resultado a sua utilização no tempo da monarquia constitucional. O regime democrático, abraçado com o 25 de abril de 1974, relançou o órgão de soberania Parlamento e estabeleceu prioridades. Até ao amadurecimento da democracia viveram-se tempos mais conturbados mas de grande aprendizagem. O inquérito Parlamentar, a partir da revisão constitucional de 1982, passou conceptualmente a integrar um dos meios mais relevantes da fiscalização política. É, pois, o levantamento exaustivo e a análise das Comissões Parlamentares de Inquérito no Portugal democrático, período de 1976-2015, o objetivo a que nos propomos neste estudo.

Fucoidan-based particles for diabetes mellitus treatment

Marine organisms are rich in a variety of materials with potential use in Tissue Engineering and Regenerative Medicine. One important example is fucoidan, a sulfated polysaccharide extracted from the cell wall of brown seaweeds.  Fucoidan is composed by L-fucose, sulfate groups and glucuronic acid. It has important bioactive properties such as anti-oxidative, anticoagulant, anticancer and reducing the blood glucose (1). In this work, the biomedical potential of fucoidan-based materials as drug delivery system was assessed by processing modified fucoidan (MFu) into particles by photocrosslinking using superamphiphobic surfaces and visible light. Fucoidan was modified by methacrylation reaction using different concentrations of methacrylate anhydride, namely 8% v/v (MFu1) and 12% v/v (MFu2). Further, MFu particles with and without insulin (5% w/v) were produced by pipetting a solution of 5% MFu with triethanolamine and eosin-y onto a superamphiphobic surface and then photocrosslinking using visible light (2). The developed particles were characterized to assess their chemistry, morphology, swelling behavior, drug release, insulin content and encapsulation efficiency. Moreover, the viability assays of fibroblast L929 cells in contact with MFu particles showed good adhesion and proliferation up to 14 days. Furthermore, the therapeutic potential of these particles using human beta cells is currently under investigation. Results obtained so far suggest that modified fucoidan particles could be a good candidate for diabetes mellitus therapeutic approaches.  

Occupational Ergonomics and Safety, Part 2

[Excerpt] This section is the second part of a special issue on Occupational Ergonomics and Safety, which was organized for WORK: A Journal of Prevention, Assessment and Rehabilitation. As in the first part of this thematic issue, this one comprises thirteen papers that were peer-reviewed and, finally, accepted for publication. This issue includes the work of authors from eleven countries all over the world. The variety of the presented works is not limited to their geographical origin, but it is also visible on the topics that are addressed, ranging from typical studies on ergonomics to safety management studies, as well as occupational hygiene topics.