Characterization of high-current pulsed arcs ranging from 100--250 kA peak

In this paper, we present the laboratory study on three experimental setups that produce a free arc channel subjected to the transient phase of a lightning current waveform. This work extends the high-current pulsed arc characterization performed in previous studies for peak levels up to 100 kA. Eleven high-current waveforms with peak value ranging from 100--250 kA with different growth rates and action integrals are studied, allowing the comparison of different test benches. These waveforms correspond to standard lightning ones used in aircraft certification processes. Hydrodynamic properties such as arc channel evolution and shock-wave propagation are determined by high-speed video imaging and the background-oriented Schlieren method. The arc diameter reaches around 90mm at 50 $\mu$s for a current of 250 kA peak. Space- and time-resolved measurements of temperature, electron density and pressure are assessed by optical emission spectroscopy associated with the radiative transfer equation. It is solved across the arc column and takes into account the assumption of non-optically thin plasma at local thermodynamic equilibrium. For a 250 kA waveform, temperatures up to 43000K are found, with pressures in the order of 50 bar. The influence of current waveform parameters on the arc properties are analyzed and discussed

A current differential line protection using a synchronous reference frame approach

This paper presents a new approach for a current differential protection of the transmission lines. This approach is based on the Park transformation or ABC-dqo transformation. Using the ABC-dqo transformation the three phase quantities are transformed into a synchronous rotating reference frame. In this way, the line currents of the three phase system are measured and transformed into three dc components. So, immunity to problems such as sampling misalignment and time delay of the communication channel will be improved. Several test results are presented in order to show the effectiveness of the proposed approach

A Rare but Real Necessity: Case Report of Coronary Artery Stenting in an Infant

Percutaneous coronary intervention (PCI) is an extremely common and well-established procedure in adults which is rarely performed in children. We present a case of a successful left main coronary artery stenting in a small infant with a congenital coronary artery anomaly. We highlight the technical challenges of performing a PCI in a small patient, the risks of antithrombotic prophylaxis in this age group, and the importance of the combined work of the adult and pediatric interventional cardiologist.info:eu-repo/semantics/publishedVersio

Traumatic diaphragmatic hernias: retrospective analysis

AIMS: This study classifies cases of traumatic diaphragmatic hernias (TDH) in patients admitted to the Intensive Care Unit (ICU) of the Coimbra University Hospitals (HUC) from 1990 to 2004. METHODS: Retrospective analysis of 34 cases of TDH, studying anatomical location, place and time of diagnosis, complementary tests aiding diagnosis, herniated organs, associated traumatism, morbidity and mortality. RESULTS: Twenty-eight male and six female patients with an average age of 40.5 years +/- 20.5, average SAPS score 38.8. Average length of stay was 19.1 +/- 13.6 days, all suffered from closed traumatism and were put on artificial ventilation. The left-side diaphragm was more frequently affected (94.1%) then the right. Diagnosis in 19 cases was made up in the first six hours following the diagnosis of traumatism, in four cases within 12 hours and in the remaining cases between 48 hours and 16 years after traumatism. In 13 patients the diagnosis was established intra-operatively. The stomach was typically one of the herniated organs. The most frequently associated lesions at the thoracic level were pulmonary contusion, haemothorax and pneumothorax, and at the abdominal level, haemoperitoneum and splenic lesion. The rates for complications and mortality were 55.8% and 11.7% respectively. CONCLUSIONS: TDH mainly occurs on the left side through closed thoraco-abdominal trauma following road traffic accidents. This group of patients, on average younger than others admitted to ICU, presents a longer average hospitalisation period, but has lower rates of mortality and lower SAPS severity scores. The most commonly herniated organ was the stomach and the most frequently encountered lesions were cranial-encephalic, splenic and pleural traumatisms. Pre-operative diagnosis of diaphragmatic injuries is difficult and a high index of clinical suspicion is needed after thoraco-abdominal trauma. This diagnosis should always be considered a possibility in cases of closed thoraco-abdominal traumas

Transmission lines protection based on the current eigenvalues differential concept

This work presents a new approach for a current differential protection of the transmission lines. The proposed approach is based on the Clarke-Concordia transformation and principal component analysis. First the acquired current signals are transformed into “αβo” components by applying the Clarke-Concordia transformation. This allows obtaining typical patterns. To identify these patterns a principal component analysis is performed. Several tests under different fault conditions were performed. The obtained results allow verifying the effectiveness of the proposed approach

Modelling of thermoelectric generator with heat pipe assist for range extender application

Recent trends towards electrification of vehicles favour the adoption of waste energy recovery into electricity. Battery-only Electric Vehicles (BEV) need a very large energy storage system so the use of a Range Extender (RE) may allow a significant downsizing of these bulky components. The Internal Combustion Engines (ICE) have two major discarded energy fluxes, engine cooling and exhaust gas. In Extended Range Electric Vehicles (EREV) and hybrids the potential for heat conversion into electricity is particularly convenient. The direct conversion of thermal energy into electricity, using Thermoelectric Generators (TEG) is very attractive in terms of complexity. However, current commercial TEG modules based on Seebeck effect are temperature limited, so they are unable to be in direct contact with the exhaust gases. A way to downgrade the temperature levels without reducing its potential is to interpose Heat Pipes (HP) between the exhaust gas and the modules. This control of maximum temperature at the modules is achieved by regulating the pressure of phase change of the HP fluid. Such design is convenient for engines with large thermal load variations, such as the RE being developed by the team, with a low (15kW) and a high (40kW) power mode of operation. This system will be able to operate efficiently in both modes. The present work presents the thermal modelling of such a system in order to assess the suitability of this approach. This work is complemented with the experimental work being carried out by the team in this subject, already with some published results. The model was validated with experimental data with a good correlation. Therefore, it was possible to demonstrate the potential of this system for wasted heat recovery.MIT Portugal, Fundação para a Ciência e a Tecnologia (FCT

Temperature controlled exhaust heat thermoelectric generation

The amount of energy wasted through the exhaust of an Internal Combustion Engine (ICE) vehicle is roughly the same as the mechanical power output of the engine. The high temperature of these gases (up to 1000°C) makes them intrinsically apt for energy recovery. The gains in efficiency for the vehicle could be relevant, even if a small percentage of this waste energy could be regenerated into electric power and used to charge the battery pack of a Hybrid or Extended Range Electric Vehicle, or prevent the actuation of a conventional vehicle's alternator.SFRH / BPD / 51048 / 2010MIT-Pt/EDAM-SMS/0030/200

Potential bio-activity of whey fermented extract as sanitizer of organic grown lettuce

Short CommunicationConsumption of vegetables is increasing due to demand for healthy products in peoples' diets. To reduce microbial contamination and maintain freshness, industrial processes in Portugal rely on minimally processing of vegetables with hypochlorite as sanitizer. Formation of toxic chlorine derivatives has raised concern restrictions to its use and alternatives with whey permeate as a disinfection agent has been attempted. The aim of this work was to evaluate the bio potential of fermented cheese whey, for use on disinfection of minimally processed lettuce organically grown. Assays were made with whey obtained from inoculated milk during cheese processing, fermented for 120 h at 37 C, after which, among other carbohydrates, lactic acid was measured by HPLC, giving average yields of 18 g L 1. The sanitizing effect of whey, undiluted, 75 and 50% solutions, was compared with 110 ppm sodium hypochlorite, after rinsing. Aerobic Microorganisms (AM), Psychrotrophic Microorganisms (PM) and Enterobacteriaceae (ENT), were used as indicators for hygiene quality. For a level of significance of P < 0.05, the hygiene quality standards of lettuce samples, were better using 75% whey solution (AM 6.62, PM 7.48 cfu g 1), than using sodium hypochlorite (AM 7.48, PM 8.15 cfu g 1), for the 7 days of shelf life studied. Evaluation of Enterobacteriaceae showed significant differences after 3 days, betweenwater (ENT 4.98 cfu g 1) sodium hypochlorite (ENT 4.81 cfu g 1) and 75% solution of whey (ENT 4.63 cfu g 1). Considering the actual limitations imposed to chlorine sanitation, these results point a good alternative to the food industry, especially for organic fresh vegetables, which are chemical free brandsinfo:eu-repo/semantics/publishedVersio

Lavandula luisieri and Lavandula viridis essential oils as upcoming anti-protozoal agents: A key focus on leishmaniasis

Background and objectives: Leishmania species is the causative agent of leishmaniasis, a broad-spectrum clinical condition that can even be life-threatening when neglected. Current therapeutic strategies, despite beings highly cost-effective, have been increasingly associated with the appearance of drug-resistant microorganisms. Thus, an increasing number of thorough studies are needed towards upcoming drug discovery. This study aims to reveal the anti-protozoa activity of Lavandula luisieri and Lavandula viridis essential oils (EO) and their main components (1,8-cineole, linalool, and borneol). Materials and Methods: L. luisieri and L. viridis EO and their main components' leishmanicidal effects were tested in vitro against Leishmania infantum, Leishmania major, and Leishmania tropica strains. Cell viability effects were estimated by using the tetrazolium-dye (MTT) colorimetric method, morphological changes were assessed by scanning electron microscopy (SEM) and ultrastructural investigation by transmission electronic microscopy (TEM). Phosphatidylserine externalization, mitochondrial membrane potential (MMP), and cathepsin D activity assessment were also carried out. Finally, cytotoxic activity of the studied matrices was also determined in mammalian cells. Results: Plant-studied EO exhibited prominent anti-Leishmania effects (IC50 = 31-263 µg/mL), with L. luisieri being the most active one. At concentrations corresponding to IC50 values, EO-exposed L. infantum promastigotes suffered marked ultrastructural modifications. The presence of aberrant-shaped cells, mitochondrial and kinetoplast swelling, and autophagosomal structures were the most common evidenced changes. L. luisieri EO exerted its leishmanicidal activity through different mechanisms, but mainly through unleashing apoptosis. Phosphatidylserine externalization, mitochondrial membrane potential loss, and cell-cycle arrest at G(0)/G(1) phase were the most remarkable apoptosis-mediated aspects. Inhibition of cathepsin D activity was also observed. No toxic effects were found on macrophage cells. Conclusions: L. luisieri seems to be an upcoming source of bioactive molecules for leishmaniasis control and to find leading molecules for new drugs formulation against Leishmania infections.This work was supported by the European Regional Development Fund (ERDF), through the Centro 2020 Regional Operational Programme under project CENTRO-01-0145-FEDER-000008:BrainHealth 2020, and through the COMPETE 2020—Operational Programme for Competitiveness and Internationalisation and Portuguese national funds via FCT—Fundação para a Ciência e a Tecnologia, I.P., under strategic project POCI-01-0145-FEDER-007440 (UID/NEU/04539/2013). Acknowledgments: The authors are grateful to Jorge Paiva for helping in plant taxonomy; to José Correia da Costa from Centro de Imunologia e Biologia Parasitária, Instituto Nacional Ricardo Jorge, Porto for supplying L. infantum (zymodeme MON-1); to António Osuna, Departamento de Parasitología, Facultad de Ciencias, Instituto de Biotecnología, Universidad de Granada, for supplying L. major. FCT for Strategic project ref. UID/BIM/04293/2013, and “NORTE2020—Programa Operacional Regional do Norte” (NORTE-01-0145-FEDER-000012)