Ressonância mecânica em cromossomas humanos

Trabalho final de mestrado integrado em Medicina, apresentado à Faculdade de Medicina da Universidade de Coimbra.Desencadear um fenómeno de ressonância mecânica em cromossomas poderá resultar na sua destruição e comprometer a sobrevivência celular. Criou-se um modelo virtual de braços de cromossomas: um cone excêntrico com características próprias de cada braço. Utilizando simulações computacionais (COMSOL Multiphysics 4.4®), chegou-se à frequência natural em dois modos de vibração de vários cromossomas. A diferença média entre as várias frequências obtidas foi de cerca de 2 kHz em ambos modos de vibração, sendo necessário adicionar 100 000 pares de bases ou aumentar 1 nm para que haja variação de 1 Hz na frequência natural. Conclui-se que modificando a massa e o comprimento dos braços dos cromossomas de forma significativa, produz-se uma alteração na frequência de ressonância. Isto poderá conduzir ao desenvolvimento de uma terapia que destrua seletivamente cromossomas.Producing a mechanical resonance phenomenon in chromosomes could lead to its destruction. A virtual model of chromosome arms was created: eccentric cone with characteristics specific for each arm. Using virtual simulations (COMSOL Multiphysics 4.4®), natural frequency was found for various chromosomes, in two modes of vibrations. The mean difference between those frequencies was about 2 kHz in both vibration modes. It was necessary to add 100,000 base pairs or increase 1 nm in chromosomes arm to get a change of 1 Hz in natural frequency. Therefore, changing mass and length of chromosome’s arm, in a significant manner, will produce a change in its resonant frequency. This could lead to a new therapy which destroys chromosomes selectively

Contribuição para o estudo da presença de disruptores endócrinos em lamas de ETAR

Dissertação para obtenção do Grau de Mestre em Engenharia do Ambiente – Perfil Engenharia SanitáriaOs compostos disruptores endócrinos são considerados poluentes ambientais na medida em que perturbam o normal funcionamento do sistema endócrino do Homem e de outros organismos, ou seja, são compostos exógenos que interferem com a homeostasia, reprodução, desenvolvimento e comportamento dos organismos. Estes compostos são constituintes de plásticos, pesticidas, herbicidas, fungicidas, detergentes, fármacos, surgindo por isso nos resíduos industriais e domésticos e em águas residuais. Geralmente, estes compostos são lipofílicos e semi-voláteis, facilitando a sua dispersão no ambiente, principalmente através da água. As águas residuais são consideradas a maior fonte de contaminação, porém, estes compostos não são totalmente removidos nos convencionais sistemas de tratamento de água residual, podendo mesmo, ser encontrados nas lamas de ETAR devido à sua natureza não polar e principalmente à sua natureza hidrofóbica. Os principais EDC encontrados e estudados em lamas de ETAR são: Bisfenol A, Nonilfenol, LAS, PCDD/F, PAHs e DEHP. Contudo, existe actualmente uma enorme lacuna, quer em termos legislativos sobre possíveis descargas destes compostos, quer em estudos efectuados sobre a remoção destes compostos em lamas de ETAR. Assim o presente estudo tem como objectivo efectuar uma revisão bibliográfica sobre a identificação de compostos disruptores endócrinos em lamas de ETAR e analisar a sua taxa de remoção, tendo em consideração os diferentes tipos de tratamento na fase sólida

Experimental assessment of the performance and emissions of a spark-ignition engine using waste-derived biofuels as additives

The use of biofuels for spark ignition engines is proposed to diversify fuel sources and reduce fossil fuel consumption, optimize engine performance, and reduce pollutant emissions. Additionally, when these biofuels are produced from low-grade wastes, they constitute valorisation pathways for these otherwise unprofitable wastes. In this study, ethanol and pyrolysis biogasoline made from low-grade wastes were evaluated as additives for commercial gasoline (RON95, RON98) in tests performed in a spark ignition engine. Binary fuel mixtures of ethanol + gasoline or biogasoline + gasoline with biofuel incorporation of 2% (w/w) to 10% (w/w) were evaluated and compared with ternary fuel mixtures of ethanol + biogasoline + gasoline with biofuel incorporation rates from 1% (w/w) to 5% (w/w). The fuel mix performance was assessed by determination of torque and power, fuel consumption and efficiency, and emissions (HC, CO, and NOx). An electronic control unit (ECU) was used to regulate the air–fuel ratio/lambda and the ignition advance for maximum brake torque (MBT), wide-open throttle (WOT)), and two torque loads for different engine speeds representative of typical driving. The additive incorporation up to 10% often improved efficiency and lowered emissions such as CO and HC relative to both straight gasolines, but NOx increased with the addition of a blend.This work was supported by FCT-Fundação para a Ciência e Tecnologia within the R&D Units, MEtRICs Project Scope: UIDP/04077/2020. Joaquim da Costa was supported through a PhD Grant from Fundo de Desenvolvimento Capital Humano of the Government of Timor Leste

Performance and emissions of a spark ignition engine operated with gasoline supplemented with pyrogasoline and ethanol

The partial replacement of fossil fuels by biofuels contributes to a reduction of CO2 emissions, alleviating the greenhouse effect and climate changes. Furthermore, fuels produced from waste biomass materials have no impact on agricultural land use and reduce deposition of such wastes in landfills. In this paper we evaluate the addition of pyrolysis biogasoline (pyrogasoline) as an additive for fossil gasoline. Pyrogasoline was produced from used cooking oils unfit to produce biodiesel. This study was based on a set of engine tests using binary and ternary mixtures of gasoline with 0, 2.5, and 5% pyrogasoline and ethanol. The use of ternary blends of gasoline and two different biofuels was tested with the purpose of achieving optimal combustion conditions and lower emissions, taking advantage of synergistic effects due to the different properties and chemical compositions of those biofuels. The tests were performed on a spark-ignition engine, operated at full load (100% throttle, or WOT—wide open throttle) between 2000 and 6000 rpm, while recording engine performance and exhaust gases pollutants data. Binary mixtures with pyrogasoline did not improve or worsen the engine’s performance, but the ternary mixtures (gasoline + pyrogasoline + ethanol) positively improved the engine’s performance with torque gains between 0.8 and 3.1% compared to gasoline. All fuels presented CO and unburned hydrocarbons emissions below those produced by this type of engine operated under normal (fossil) gasoline. On the other hand, NOx emissions from oxygenated fuels had contradictory behaviour compared to gasoline. If we consider the gains achieved by the torque with the ternary mixtures and reductions in polluting emissions obtained by mixtures with pyrogasoline, a future for this fuel can be foreseen as a partial replacement of fossil gasoline.This work was partially funded by Fundação para a Ciência e Tecnologia: UIDB/04077/2020

The effect of ambient pressure on the heat transfer of a water spray

The present work is aimed at quantifying the effects of ambient pressure in the heat transfer at single injections of a full cone spray over a hot metal surface. The experimental configuration is that of a spray impinging down perpendicularly onto a flat surface located at 55 mm inside an injection chamber. The experiments were conducted for prescribed initial wall temperatures ranging from single phase to local nucleate boiling and transition regimes of heat transfer. Ambient pressures ranged from atmospheric to 30 bar. The analysis is based on spatial resolved measurements of the instantaneous surface temperature during the injection period. The measurements are then processed in order to obtain estimates of the time-averaged values of the local heat flux. The overall cooling rate is also obtained by integrating the local values within the total area of the spray impact Results show that the amount of heat extracted by the impinging spray increases 3.4 times when ambient pressure is increased from atmospheric to 20 bar at the same superheating degree at the wall of 45 degrees C. This corresponds to an increase from 13.3% to 47.7% in the ratio between the actual cooling and the theoretical maximum cooling, defined here as cooling efficiency. This is a result of a better spreading of the liquid film at the wall, covering a larger footprint upon impact. Instantaneous peak heat flux is also increased, as a clear indication of the improved heat transfer between the impinging droplets and the wall.The work presented herein derives from a broader research program devised to develop a system for in cylinder cooling of internal combustion engines using high pressure water sprays produced by gasoline direct injectors.The authors would like to acknowledge LiquidPiston INC. for providing all the laboratorial conditions to perform the experiments, MEtRICs - Mechanical Engineering and Resource Sustainability Centre (UID/EMS/04077/2019), and Diogo Ferreira for aiding in the highspeed visualization setup and experiments. T. Costa is supported by the Portuguese Foundation for Science and Technology (FCT) under the PhD grant PD/BD/105929/2014, MIT Portugal Program, and F.P. Brito is supported by FCT under the Post doctoral grant SFRH/BPD/89553/2012 and J. Martins is supported by the FCT grant SFRH/BSAB/142994/2018, financed by FEDER funds through Programa Operacional Fatores de Competitividade - COMPETE and National funds through PIDDAC and FCT

Gestão do desenvolvimento de software com o uso de quadro virtual Kanban/ Software development management with the use of Kanban virtual board

O método Kanban tem sido utilizado para evidenciar gargalos na produção de software em diversas empresas de desenvolvimento. A proposta inicial do Kanban prevê o uso de um quadro físico para controle e visualização das atividades. Esta proposta sugere que o quadro seja construído de maneira virtual tanto para melhorar o vínculo entre o que é falado e o que é escrito quanto para permitir a extração de métricas de maneira automatizada. Para endossar a proposta, foram analisados dados de aproximadamente dois anos de utilização de quadro virtual Kanban em uma empresa de desenvolvimento de software, com o objetivo de verificar a aderência das informações apresentadas no quadro em relação ao real estágio de desenvolvimento por meio da comparação desses dados com os dados obtidos nos controladores de versionamento de código fonte. Desta forma, foi possível observar algumas divergências entre as marcações o que mostra que há espaço para melhorias

Ta2O5/SiO2 Multicomponent Dielectrics for Amorphous Oxide TFTs

Co-sputtering of SiO2 and high-κ Ta2O5 was used to make multicomponent gate dielectric stacks for In-Ga-Zn-O thin-film transistors (IGZO TFTs) under an overall low thermal budget (T = 150 °C). Characterization of the multicomponent layers and of the TFTs working characteristics (employing them) was performed in terms of static performance, reliability, and stability to understand the role of the incorporation of the high-κ material in the gate dielectric stack. It is shown that inherent disadvantages of the high-κ material, such as poorer interface properties and poor gate insulation, can be counterbalanced by inclusion of SiO2 both mixed with Ta2O5 and as thin interfacial layers. A stack comprising a (Ta2O5)x(SiO2)100 − x film with x = 69 and a thin SiO2 film at the interface with IGZO resulted in the best performing TFTs, with field-effect mobility (µFE) ≈ 16 cm2·V−1·s−1, subthreshold slope (SS) ≈ 0.15 V/dec and on/off ratio exceeding 107. Anomalous Vth shifts were observed during positive gate bias stress (PGBS), followed by very slow recoveries (time constant exceeding 8 × 105 s), and analysis of the stress and recovery processes for the different gate dielectric stacks showed that the relevant mechanism is not dominated by the interfaces but seems to be related to the migration of charged species in the dielectric. The incorporation of additional SiO2 layers into the gate dielectric stack is shown to effectively counterbalance this anomalous shift. This multilayered gate dielectric stack approach is in line with both the large area and the flexible electronics needs, yielding reliable devices with performance suitable for successful integration on new electronic applications.publishersversionpublishe

CavBench: a benchmark for protein cavity detection methods

Extensive research has been applied to discover new techniques and methods to model protein-ligand interactions. In particular, considerable efforts focused on identifying candidate binding sites, which quite often are active sites that correspond to protein pockets or cavities. Thus, these cavities play an important role in molecular docking. However, there is no established benchmark to assess the accuracy of new cavity detection methods. In practice, each new technique is evaluated using a small set of proteins with known binding sites as ground-truth. However, studies supported by large datasets of known cavities and/or binding sites and statistical classification (i.e., false positives, false negatives, true positives, and true negatives) would yield much stronger and reliable assessments. To this end, we propose CavBench, a generic and extensible benchmark to compare different cavity detection methods relative to diverse ground truth datasets (e.g., PDBsum) using statistical classification methods.info:eu-repo/semantics/publishedVersio