2,229 research outputs found
A Survey on Electric / Hybrid Vehicles
Since the late 19th century until recently several electric vehicles have been designed, manufactured and used throughout the world. Some were just prototypes, others were concept cars, others were just special purpose vehicles and lately, a considerable number of general purpose cars has been produced and commercialized.
Since the mid nineties the transportation sector emissions are being increasingly regulated and the dependency on oil and its price fluctuations originated an increasing interest on electric vehicles (EV).
A wide research was made on existing electric/hybrid vehicle models. Some of these vehicles were just in the design phase, but most reached the prototype or full market production. They were divided into several types, such as NEVs, prototypes, concept cars, and full homologated production cars. For each type of vehicle model a technical historic analysis was made. Data related to the vehicle configuration as well as the embedded systems were collected and compared. Based on these data future prospect of evolution was subsequently made.
The main focus was put on city vehicles and long range vehicles. For city vehicles the market approach normally consists in the use of full electric configuration while for the latter, the hybrid configuration is commonly used. The electrical systems and combustion engines found in these vehicles are compared in order to forecast the evolution trend in terms of specifications and performance of the whole vehicle and of each system.MIT Portugal, Fundação para a Ciência e a Tecnologia (FCT
Especialização produtiva e comercial de Trás-os-Montes e Alto Dopuro - um sério entrave ao seu desenvolvimento
Nesta comunicação propomo-nos apresentar os aspectos relativos à especialização produtiva e padrão de comércio internacional da região de TMAD, neste estudo considerada como o somatório das nuts 3 Alto Trás-os-Montes e Douro, procurando desta forma contribuir para identificar e clarificar as especificidades mais relevantes por si evidenciadas. Verificamos que TMAD apresenta um perfil económico distinto do da Região Norte (RN) e do país, o mesmo acontecendo com o seu comércio externo. Por outro lado, os estudos conhecidos sobre o desenvolvimento económico e social das regiões portuguesas apontam TMAD como uma das menos desenvolvidas do país. O atraso estrutural face às demais regiões, especialmente motivado por razões económicas, conduz à necessidade de se proceder a uma análise do perfil económico da região e da respectiva evolução.
TMAD é uma economia muito fechada ao exterior, com uma vocação exportadora muito frágil. Os problemas de funcionamento dos mercados são um dos principais estrangulamentos à estrutura produtiva da região. É por isso necessário orientar a oferta local para a captação de clientes não residentes. A proximidade a Castela e Leão e à Galiza, sem esquecer a Região Norte do país, possibilitam o desenvolvimento de uma estratégia orientada para estes mercados. É com a expansão dos mercados que se pode criar as condições para uma estratégia ao nível do mercado internacional
Chemical abundances for the transiting planet host stars OGLE-TR-10, 56, 111, 113, 132 and TrES-1. Abundances in different galactic populations
We used the UVES spectrograph (VLT-UT2 telescope) to obtain high-resolution
spectra of 6 stars hosting transiting planets, namely for OGLE-TR-10, 56, 111,
113, 132 and TrES-1. The spectra are now used to derive and discuss the
chemical abundances for C, O, Na, Mg, Al, Si, S, Ca, Sc, Ti, V, Cr, Mn, Co, Ni,
Cu and Zn. Abundances were derived in LTE, using 1-D plane-parallel Kurucz
model atmospheres. For S, Zn and Cu we used a spectral synthesis procedure,
while for the remaining cases the abundances were derived from measurements of
line-equivalent widths. The resulting abundances are compared with those found
for stars in the solar neighborhood. Distances and galactic coordinates are
estimated for the stars. We conclude that besides being particularly
metal-rich, with small possible exceptions OGLE-TR-10, 56, 111, 113, 132 and
TrES-1 are chemically undistinguishable from the field (thin disk) stars
regarding their [X/Fe] abundances. This is particularly relevant for the most
distant of the targets, located at up to ~2 Kpc from the Sun. We also did not
find any correlation between the abundances and the condensation temperature of
the elements, an evidence that strong accretion of planetary-like material,
tentatively connected to planetary migration, did not occur.Comment: Accepted for publication in Astronomy & Astrophysics (June 2006
A mechanical analysis of polydicyclopentadiene with metal inserts through flexural load
Polydicyclopentadiene (PDCPD) is being used in several products with particular success regarding to weight reduction and surface finish improvement. Despite the enough good mechanical properties presented by this thermosetting polymer, it needs to be adequately reinforced in applications requiring extra structural stability. This work studies the improvement of mechanical properties that may be achieved in PDCPD components reinforced with over-moulded steel wires by using the reaction injection moulding (RIM). Specimens, with and without metal inserts, were produced by using a special dedicated developed prototype RIM mould to be submitted to three point bending test, according to EN ISO 178:2003 standard. This paper presents and discusses the results obtained from the flexural tests, which allow concluding that the solution could be industrially used in feasible and advantageous conditions.Fundação para a Ciência e a Tecnologia (FCT)Fundos FEDER, Programa Operacional para Fatores de Competitividade – COMPETE, projeto 1384
Optical fiber-based sensing method for nanoparticle detection through supervised back-scattering analysis: A potential contributor for biomedicine
Background: In view of the growing importance of nanotechnologies, the detection/identification of nanoparticles type has been considered of utmost importance. Although the characterization of synthetic/organic nanoparticles is currently considered a priority (eg, drug delivery devices, nanotextiles, theranostic nanoparticles), there are many examples of “naturally” generated nanostructures - for example, extracellular vesicles (EVs), lipoproteins, and virus - that provide useful information about human physiology or clinical conditions. For example, the detection of tumor-related exosomes, a specific type of EVs, in circulating fluids has been contributing to the diagnosis of cancer in an early stage. However, scientists have struggled to find a simple, fast, and low-cost method to accurately detect/identify these nanoparticles, since the majority of them have diameters between 100 and 150 nm, thus being far below the diffraction limit. Methods: This study investigated if, by projecting the information provided from short-term portions of the back-scattered laser light signal collected by a polymeric lensed optical fiber tip dipped into a solution of synthetic nanoparticles into a lower features dimensional space, a discriminant function is able to correctly detect the presence of 100 nm synthetic nanoparticles in distilled water, in different concentration values. Results and discussion: This technique ensured an optimal performance (100% accuracy) in detecting nanoparticles for a concentration above or equal to 3.89 µg/mL (8.74E+10 particles/mL), and a performance of 90% for concentrations below this value and higher than 1.22E-03 µg/mL (2.74E+07 particles/mL), values that are compatible with human plasmatic levels of tumorderived and other types of EVs, as well as lipoproteins currently used as potential biomarkers of cardiovascular diseases. Conclusion: The proposed technique is able to detect synthetic nanoparticles whose dimensions are similar to EVs and other “clinically” relevant nanostructures, and in concentrations equivalent to the majority of cell-derived, platelet-derived EVs and lipoproteins physiological levels. This study can, therefore, provide valuable insights towards the future development of a device for EVs and other biological nanoparticles detection with innovative characteristics.This work was partly developed under the project NanoSTIMA, funded by the North Portugal Regional Operational Program (NORTE 2020), under the PORTUGAL 2020 Partnership Agreement, and through the European Regional Development Fund (ERDF). It was also funded by the Portuguese Foundation for Science and Technology (PhD research grant PD/BD/135023/2017). Rita SR Ribeiro is currently working at 4Dcell and Elvesys, Paris, France
In Vitro Screening
This research was funded by Fundação para a Ciência e a Tecnologia (FCT-MCTES), Radiation Biology and the Biophysics Doctoral Training Programme (RaBBiT, PD/00193/2012);
the scholarship grant number PD/BD/142829/2018, to T.P.P. from the RaBBiT Doctoral Training Programme.
Publisher Copyright:
© 2023 by the authors.Photodynamic therapy is a minimally invasive procedure used in the treatment of several diseases, including some types of cancer. It is based on photosensitizer molecules, which, in the presence of oxygen and light, lead to the formation of reactive oxygen species (ROS) and consequent cell death. The selection of the photosensitizer molecule is important for the therapy efficiency; therefore, many molecules such as dyes, natural products and metallic complexes have been investigated regarding their photosensitizing potential. In this work, the phototoxic potential of the DNA-intercalating molecules—the dyes methylene blue (MB), acridine orange (AO) and gentian violet (GV); the natural products curcumin (CUR), quercetin (QT) and epigallocatechin gallate (EGCG); and the chelating compounds neocuproine (NEO), 1,10-phenanthroline (PHE) and 2,2′-bipyridyl (BIPY)—were analyzed. The cytotoxicity of these chemicals was tested in vitro in non-cancer keratinocytes (HaCaT) and squamous cell carcinoma (MET1) cell lines. A phototoxicity assay and the detection of intracellular ROS were performed in MET1 cells. Results revealed that the IC50 values of the dyes and curcumin in MET1 cells were lower than 30 µM, while the values for the natural products QT and EGCG and the chelating agents BIPY and PHE were higher than 100 µM. The IC50 of MB and AO was greatly affected by irradiation when submitted to 640 nm and 457 nm light sources, respectively. ROS detection was more evident for cells treated with AO at low concentrations. In studies with the melanoma cell line WM983b, cells were more resistant to MB and AO and presented slightly higher IC50 values, in line with the results of the phototoxicity assays. This study reveals that many molecules can act as photosensitizers, but the effect depends on the cell line and the concentration of the chemical. Finally, significant photosensitizing activity of acridine orange at low concentrations and moderate light doses was demonstrated.publishersversionpublishe
Calibration of the numerical model of a freight railway vehicle based on experimental modal parameters
The simulation of the dynamic behavior of the train-track system is strongly dependent on the accuracy of the numerical models of the train and track subsystems. The use of calibrated numerical models of the railway vehicles, based on experimental data, enhances their ability to correctly reproduce the dynamic responses of the train under operational conditions. In this scope, studies involving the experimental calibration of freight wagon models are still scarce. This article aims to fill this gap by presenting an efficient methodology for the calibration of a numerical model of a freight railway wagon based on experimental modal parameters. A dynamic test was performed during the unloading operation of the train, adopting a dedicated approach which does not interfere with its tight operational schedule. From data collected during the dynamic test, five natural frequencies and mode shapes associated with rigid-body and flexural movements of the wagon platform were identified through the Enhanced Frequency-Domain Decomposition (EFDD) method. A detailed 3D finite-element (FE) model of the loaded freight wagon was developed, requiring precise knowledge of the vehicle design details which, in most situations, are difficult to obtain due to confidentiality reasons of the manufacturers. The model calibration was performed through an iterative method based on a genetic algorithm and allowed to obtain optimal values for seven numerical parameters related to the suspension’s stiffnesses and mass distribution. The stability of the parameters considering different initial populations demonstrated the robustness of the optimization algorithm. The average error of the natural frequencies decreased from 8.5% before calibration to 3.2% after calibration, and the average MAC values improved from 0.911 to 0.950, revealing a significant improvement of the initial numerical model.The authors would like to acknowledge the support of the Base Funding UIDB/04708/2020 and Programmatic Funding UIDP/04708/2020 of the CONSTRUCT (Instituto de I&D em Estruturas e Construções) funded by national funds through the FCT/MCTES (PIDDAC). The authors also express their gratitude to Dr. Nuno Pinto and Mr. Valdemar Luís, both technicians of LESE laboratory, for their indispensable assistance during the preparation and execution of the experimental testinfo:eu-repo/semantics/publishedVersio
Oromucosal Alginate Films with Zein Nanoparticles as a Novel Delivery System for Digoxin
Digoxin is a hydrophobic drug used for the treatment of heart failure that possesses a narrow therapeutic index, which raises safety concerns for toxicity. This is of utmost relevance in specific populations, such as the elderly. This study aimed to demonstrate the potential of the sodium alginate films as buccal drug delivery system containing zein nanoparticles incorporated with digoxin to reduce the number of doses, facilitating the administration with a quick onset of action. The film was prepared using the solvent casting method, whereas nanoparticles by the nanoprecipitation method. The nanoparticles incorporated with digoxin (0.25 mg/mL) exhibited a mean size of 87.20 ± 0.88 nm, a polydispersity index of 0.23 ± 0.00, and a zeta potential of 21.23 ± 0.07 mV. Digoxin was successfully encapsulated into zein nanoparticles with an encapsulation efficiency of 91% (±0.00). Films with/without glycerol and with different concentrations of ethanol were produced. The sodium alginate (SA) films with 10% ethanol demonstrated good performance for swelling (maximum of 1474%) and mechanical properties, with a mean tensile strength of 0.40 ± 0.04 MPa and an elongation at break of 27.85% (±0.58), compatible with drug delivery application into the buccal mucosa. The current study suggests that SA films with digoxin-loaded zein nanoparticles can be an effective alternative to the dosage forms available on the market for digoxin administration
A modeling domain-specific language for IoT-enabled operating systems
With the increased complexity of low-end devices in the Internet of Things (IoT), mainly due to the connectivity and interoperability requirements, the development and configuration of embedded operating systems (OSes) for such devices is not straight forward. The complexity of the communication requirements is usually mitigated by the OS, e.g., the Contiki-OS, as it already incorporates an IoT-compliant network stack. Yet, the configuration of such stack requires major knowledge on the code structure, leading to additional development time, particularly when the network comprises several wireless nodes and individual configurations with subsequent firmware that needs to be generated. Based on a developed software modeling domain-specific language, this paper presents the EL4IoT framework. It aims to reduce and ease the development time by promoting a design automation tool that can configure, and automatically generate code (ready to compile) for low-end IoT devices running the Contiki-OS. Although leveraging the whole Contiki-OS modeling, this work only refactored and modeled the network stack while approaching the OS itself as one big building block or component. The proposed approach can be extended to other IoT-enabled OSes as well as integrated in other design automation tools.This work has been supported by COMPETE: POCI-01-0145-FEDER-007043 and FCT - Fundação para a Ciência e Tecnologia within the Project Scope: UID/CEC/00319/2013. Tiago Gomes is supported by FCT PhD grant SFRH/BD/90162/2012
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