Febrifugine derivative antimalarial activity: quantum mechanical predictors

Plasmodium falciparum resistant strain development has encouraged the search for new antimalarial drugs. Febrifugine is a natural substance with high activity against P. falciparum presenting strong emetic property and liver toxicity, which prevent it from being used as a clinical drug. The search for analogues that could have a better clinical performance is a current topic. We aim to investigate the theoretical electronic structure by means of febrifugine derivative family semi-empirical molecular orbital calculations, seeking the electronic indexes that could help the design of new efficient derivatives. The theoretical results show there is a clustering in well-defined ranges of several electronic indexes of the most selective molecules. The model proposed for achieving high selectivity was tested with success.

Strange Dynamics in a Fractional Derivative of Complex-Order Network of Chaotic Oscillators

We study the peculiar dynamical features of a fractional derivative of complex-order network. The network is composed of two unidirectional rings of cells, coupled through a "buffer" cell. The network has a Z3 × Z5 cyclic symmetry group. The complex derivative Dα±jβ, with α, β ∈ R+ is a generalization of the concept of integer order derivative, where α = 1, β = 0. Each cell is modeled by the Chen oscillator. Numerical simulations of the coupled cell system associated with the network expose patterns such as equilibria, periodic orbits, relaxation oscillations, quasiperiodic motion, and chaos, in one or in two rings of cells. In addition, fixing β = 0.8, we perceive differences in the qualitative behavior of the system, as the parameter c ∈ [13, 24] of the Chen oscillator and/or the real part of the fractional derivative, α ∈ {0.5, 0.6, 0.7, 0.8, 0.9, 1.0}, are varied. Some patterns produced by the coupled system are constrained by the network architecture, but other features are only understood in the light of the internal dynamics of each cell, in this case, the Chen oscillator. What is more important, architecture and/or internal dynamics?

The effect of adhesive thickness on the mechanical behavior of a structural polyurethane adhesive

One parameter that influences the adhesively bonded joints performance is the adhesive layer thickness. Hence, its effect has to be investigated experimentally and should be taken into consideration in the design of adhesive joints. Most of the results from literature are for typical structural epoxy adhesives which are generally formulated to perform in thin sections. However, polyurethane adhesives are designed to perform in thicker sections and might have a different behavior as a function of adhesive thickness. In this study, the effect of adhesive thickness on the mechanical behavior of a structural polyurethane adhesive was investigated. The mode I fracture toughness of the adhesive was measured using double-cantilever beam (DCB) tests with various thicknesses of the adhesive layer ranging from 0.2 to 2 mm. In addition, single lap joints (SLJs) were fabricated and tested to assess the influence of adhesive thickness on the lap-shear strength of the adhesive. An increasing fracture toughness with increasing adhesive thickness was found. The lap-shear strength decreases as the adhesive layer gets thicker, but in contrast to joints with brittle adhesives the decrease trend was less pronounced.

Mechanical properties of chemically modified portuguese pinewood

To turn wood into a construction material with enhanced properties, many methods of chemical modification have been developed in the last few decades. In this work, mechanical properties of pine wood were chemically modified, compared and evaluated. Maritime pine wood (Pinus pinaster) was modified with four chemical processes: 1,3-dimethylol-4,5- dihydroxyethyleneurea, N-methylol melamine formaldehyde, tetra-alkoxysilane and wax. The following mechanical properties were assessed experimentally: Modulus of elasticity measured statically, stiffness stabilization efficiency in different climates (30 and 87% of relative humidity), modulus of rupture, work maximum load, impact bending strength, compression, tensile and shear strength at indoor conditions (65% of relative humidity). In both types of active principle of modification, cell wall or lumen fill, no significant changes on the bending stiffness (modulus of elasticity) were found. In the remaining properties analysed significant changes in the modified wood-material took place compared to unmodified wood control: - Cell wall modification was the most effective method to achieve high stiffness stabilization efficiency (up to 60%) and also increased compression strength (up to 230%). However, modulus of rupture, tensile, shear and the impact bending strength were reduced by both resins, but in a varying extent, where the N-methylol melamine formaldehyde endured less reduction than 1,3-dimethylol-4,5-dihydroxyethyleneurea resin. In the latter, reduction up to 60% can take place. - In the lumen fill modification: tetra-alkoxysilane has no effect in the mechanical properties. Although, a slight increase in shear strength parallel to the grain was found. Wax specimens have shown a slight increase in bending strength, compression, tensile and shear strength as well as in the absorption energy capacity.

An organizational culture approach to performance in information technology micro-firms

This study aims to analyze and compare micro-firms’ organizational culture related to organizational performance. A case study methodology was used based on four firms, competitors among themselves in the Information Technology business, focusing on the years between 2008-2013. Findings pointed out many similarities to larger firms, but some specificities of micro-firms were found and propositions were defined: clan culture predominance is related to best performing micro-firms; the configuration of several culture types seemed to be the most suitable for obtaining good organizational results, provided that they do not focus only on hierarchy and market types of culture; the market culture predominance perception by employees is associated with low job satisfaction; and, after a certain time in business, micro-firms, as do larger companies, seek to standardize and control processes. Recognizing that organizational culture is considered important to firms’ results, this study sheds some light on that important factor for micro-firms.

Análise da viabilidade económica da implementação de uma central de micro-cogeração no setor da agropecuária

O crescente aumento do consumo energético das sociedades desenvolvidas e emergentes, motivado pelo progresso económico e social, tem induzido a procura de alternativas focalizadas nas energias renováveis, que possam contribuir para assegurar o fornecimento de energia sem agravar o consumo de combustíveis fósseis e a emissão de gases com efeito de estufa. Nesse sentido, a produção de energia eléctrica a partir do gás metano resultante da estabilização anaeróbia de efluentes tem vindo a ser estudada e praticada desde finais do século XIX, tendo assumido maior expressão a partir dos anos 70 do século XX, na sequência das primeiras crises petrolíferas. As instalações agropecuárias reúnem dois fatores chave para o sucesso do aproveitamento energético do biogás produzido no tratamento dos efluentes: por um lado, produzem matéria-prima com potencial energético – dejeto animal com um potencial enorme de criação de biogás quando procedido de tratamento anaeróbio - e, por outro, necessitam de energia eléctrica para o funcionamento dos equipamentos electromecânicos e de calor para a manutenção das instalações. A valorização energética do biogás produzido na estabilização anaeróbia dos efluentes agro-pecuários, para além de permitir obter um retorno financeiro, que contribui para o equilíbrio dos custos de investimento e de exploração, contribui igualmente para a redução das emissões de gases com efeito de estufa, como o dióxido de carbono e o metano, e para a segurança de abastecimento energético à instalação, na medida em que assegura a alimentação de energia eléctrica em caso de falha no fornecimento pela rede nacional. A presente dissertação apresenta um contributo para estudos a desenvolver por proprietários de agropecuárias, cooperativas regionais do setor da agropecuária, empresas de projecto e estudantes de Engenharia, constituído por uma compilação da informação mais relevante associada à estabilização anaeróbia de efluentes e à valorização energética do biogás produzido. Com base em informação referente ao número real de animais existentes em Portugal, este trabalho pretende fazer ver a essas entidades que o aproveitamento energético do biogás é viável e útil para o país. Com a criação de uma aplicação informática de análise económica de investimento, provar que o investimento em pequenas propriedades, com apenas 80 cabeças normais, pode obter um retorno financeiro razoável, com um prazo de recuperação do investimento bastante baixo, aproveitando um recurso que caso contrário será desperdiçado e poluirá o ambiente.

Archaeometallurgical study of pre and protohistoric production remains and artefacts from Southern Portugal

Dissertação para obtenção do Grau de Doutor em Conservação e Restauro, especialidade Ciências da Conservação

Desenvolvimento de um sensor para detecção de nano e micro concentrações de deltametrina

Dissertação para obtenção do Grau de Mestre em Engenharia Física

Multiple Mechanical Complications in ST-Segment Elevation Myocardial Infarction with Angiographically Normal Coronary Arteries

This case report discusses an unusual presentation of ST-segment elevation myocardial infarction (STEMI) with normal coronary arteries and severe mechanical complications successfully treated with surgery. An 82-year-old man presented STEMI with angiographically normal coronary arteries and no major echocardiographic alterations at discharge. At the first month follow-up, he complained of fatigue and dyspnea, and contrast echocardiography complemented by cardiac magnetic resonance imaging revealed a large left ventricular apical aneurysm with a thrombus communicating by two jets of a turbulent flow to an aneurysmatic formation of the right ventricular apex. The patient underwent a Dor procedure, which was successful. Ventricular septal defects and ventricular aneurysms are rare but devastating complications of STEMI, with almost all patients presenting multivessel coronary artery disease. Interestingly in this case, the angiographic pattern was normal.

Estudos sobre a epidemiologia da doença de Chagas no estado do Ceará - Brasil VI - estudos em uma micro-área de russas

Do Ceará, estado com problema de Doença de Chagas, Russas tem recebido a maior soma de investigações, verificando-se 11,6% de infecção humana, em 1959. Recentemente foram examinados cães, gatos e outros animais encontrando-se altas taxas de infecção. Selecionou-se, na presente pesquisa, uma micro-área (Fazenda Boa Vista) na região, onde haviam sido antes examinados 52 cães e 21 gatos, com 11 cães e 10 gatos positivos. Foram examinados mais 12 cães e 10 gatos, com 1 e 5 positivos, respectivamente, elevando-se a taxa de positividade global para 29,5%. Nessa micro-área foram examinados 125 pessoas pela RFC e pelo xenodiagnóstico, encontrando-se uma positividade de 7,2%. Desses positivos, 55% residem em casas com animal positivo, sendo que duas casas apresentaram duas pessoas positivas cada. Do total de xenos somente dois foram positivos. Na micro-área foram capturados 405 triatomíneos, com 27,7% positivos, dentro e fora das casas (galinheiros, currais, paredes externas, telheiros e alpendres). A espécie prevalente é o Triatoma brasiliensis (93,5%), encontrada dentro das casas (52,8%) com taxa de infecção de 30,2% e fora das casas (47,2%) com 24,6% de infecção. No total da região examinada na pesquisa anterior, as taxas de infecção foram 19,6% dentro das casas e 21,8% fora. A segunda espécie é o T. pseudomaculata (5,4%), encontrado mais fora das casas (72,8%) e infectado 25%. Foram capturados 8 exemplares de P. megistus sempre fora das casas, sendo 4 na micro-área; 5 exemplares estavam infectados. Na micro-área, tal como em 2 outras áreas da região, foram encontrados roedores domésticos e marsupiais com T. cruzi: 4 em 10 Rattus rattus e 1 em 3 Didelphis azarae, tal como já havia sido verificado por um dos AA. em outras áreas do Estado. Conclui-se pela existência de um dinâmico ciclo doméstico e paradoméstico de circulação do T. cruzi na micro-área, com abundantes oportunidades de infecção do homem e dos animais domésticos.

A Homemade Snare: An Alternative Method for Mechanical Removal of Dirofilaria Immitis in Dogs

Canine dirofilariosis is a life-threatening parasitic disease that is increasingly reported worldwide. Once diagnosed the main treatment goals are to improve the animal's clinical condition and to eliminate all life stages of the parasite with minimal posttreatment side effects. This can be achieved through mechanical, surgical, or chemotherapeutical approaches. Currently, manual extraction is the preferred method to remove adult heartworms due to its diminished invasiveness, reduced damage to the vascular endothelium, and shortened anaesthesia duration. However, it remains an expensive technique that can be highly traumatic. To address this issue, a nontraumatic homemade catheter-guided snare was developed for heartworm removal by adapting and folding a 0.014-inch coronary wire (BMW, Abbott Vascular). Transvenous heartworm extraction was performed on a dog severely infected with adult heartworms by inserting the modified snare into a 6-F Judkins right coronary guiding catheter BMW (Cordis) and advancing it into the right ventricle under fluoroscopic guidance. Fifteen adult specimens of Dirofilaria immitis were successfully extracted from the pulmonary artery and right ventricle without complications. To assure the death of both larvae and adults, postoperative treatment was successfully managed using ivermectin, doxycycline, and melarsomine, with no recurrence after surgery.

Towards cryogenic liquid –vapor energy storage units for space applications

Dissertation to obtain the Doctoral degree in Physics Engineering

Old cellulose for new multifunctional networks

Dissertação para obtenção do Grau de Doutor em Ciência e Engenharia de Materiais

Influence of curing conditions in lime-metakaolin blended mortars – A mineralogical and mechanical study

3rd Historic Mortars Conference, 11-14 September 2013, Glasgow, Scotland

Imunobiossensores capacitivos interdigitais com camadas sensíveis micro e nano-estruturadas

Dissertação para obtenção do Grau de Mestre em Biotecnologia