747 research outputs found

    Slowly Rotating Anisotropic Neutron Stars in General Relativity and Scalar-Tensor Theory

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    Some models (such as the Skyrme model, a low-energy effective field theory for QCD) suggest that the high-density matter prevailing in neutron star interiors may be significantly anisotropic. Anisotropy is known to affect the bulk properties of nonrotating neutron stars in General Relativity. In this paper we study the effects of anisotropy on slowly rotating stars in General Relativity. We also consider one of the most popular extensions of Einstein's theory, namely scalar-tensor theories allowing for spontaneous scalarization (a phase transition similar to spontaneous magnetization in ferromagnetic materials). Anisotropy affects the moment of inertia of neutron stars (a quantity that could potentially be measured in binary pulsar systems) in both theories. We find that the effects of scalarization increase (decrease) when the tangential pressure is bigger (smaller) than the radial pressure, and we present a simple criterion to determine the onset of scalarization by linearizing the scalar-field equation. Our calculations suggest that binary pulsar observations may constrain the degree of anisotropy or even, more optimistically, provide evidence for anisotropy in neutron star cores.Comment: 19 pages, 7 figures, 1 table. Matches version in press in CQG. Fixed small typo

    Development and assessment to environmentally friendly natural fiber composites

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    Two different types of natural fibers (jute and sisal) were studied and characterized, using optical microscopy, pycnometry density, single filament and linear density tests. Jute fibers were processed into composite parts from woven fabrics raw-material and sisal fibers were also processed into final composite componentes but in the form of chopped mat. Those fibers were used to reinforce polyester and epoxy matrices and therefore produce composite plates by resin infusion molding. Finally, the final obtained composite plates were submitted to mechanical testing, in order to assess their relevant mechanical properties.Fundação para a Ciência e a Tecnologia (FCT

    Evaluation of the Performance of Three Spacers

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    Agradecimentos às empresas GlaxoSmithKline (Portugal) e Astrazeneca (Suécia), pela cedência das câmaras de expansão Volumatic ® e NebuChamber®, respectivamente.Introdução: Existem vários factores que afectam a distribuição do fármaco nas vias áreas inferiores, onde podemos destacar os factores associados ao próprio dispositivo de inalação. Este trabalho tem como objectivo avaliar o desempenho da libertação de fármaco em três câmaras de expansão, assim como a quantidade de agente activo depositada no seu interior. Materiais e Métodos: Foi utilizado o Impinger Líquido de vários estágios (MSLI) de modo a avaliar o comportamento das partículas da suspensão Ventilan®HFA acoplado a três câmaras de expansão (Volumatic®, AeroChamber MAX® e NebuChamber®), de acordo com a Farmacopeia Portuguesa. A massa de sulfato de salbutamol recolhida nos diferentes compartimentos do impinger e no corpo da câmara foi determinada por espectrofotometria de modo a determinar a percentagem de massa cumulativa para cada câmara, determinando-se a fracção de partículas finas. Utilizou-se a Análise de Variância simples (One-way ANOVA) com o teste Post-Hoc de Bonferroni para a comparação dos resultados. Resultados: A deposição do sulfato de salbutamol ocorreu fundamentalmente no corpo das três câmaras, aproximadamente entre 40 a 50 %. Esta deposição é ligeiramente inferior na NebuChamber® (média±desvio-padrão: 43,8 % ± 11,6 %), mas não significativa relativamente à Volumatic® (p=0,351) ou à AeroChamber MAX® (p=0,115). A fracção de partículas finas assume valores de: 28,2 % ± 4,1 %, 29,6 % ± 2,4 % e 30,9 % ± 6,7 % para a Volumatic®, AeroChamber MAX® e NebuChamber®, respectivamente. Conclusão: As câmaras de expansão estudadas apresentam eficácias semelhantes na veiculação de sulfato de salbutamol aos estágios mais inferiores, não tendo sido encontrada relação entre os resultados e as suas características de volume, forma e material constituinte. Deste modo, a Volumatic® aparenta ser a câmara ideal para um hospital, uma vez que o seu grande volume não constitui uma desvantagem, sendo que o seu preço, inferior relativamente às anteriores, constitui uma vantagem de extrema importância para os hospitais públicos.Introduction: Several aspects are known to influence the drug distribution within the low respiratory tract, with particular emphasis on those related to the inhalation device. The aim of this work was to assess the performance of three spacers in the drug release, and also the quantity of active agent deposited inside these devices. Materials and Methods: In order to evaluate the behaviour of particles in suspension delivered through the Ventilan®HFA inhaler coupled to three different spacers (Volumatic®, AeroChamber MAX® and NebuChamber®) the Multistage Liquid Impinger (MSLI) was used, according to the Portuguese Pharmacopoeia. The mass of salbutamol sulphate deposited on the different impinger compartments and inside the spacer was determined by spectrophotometry, with the purpose of determining the percentage of cumulative mass for each spacer, and then the fine particle fraction. The results were compared statistically using a one-way analysis of variance (one-way ANOVA) with a Bonferroni post-hoc test. Results: About 40 to 50% of salbutamol sulphate was found deposited in the body of the three spacers. This deposition was slightly lower for NebuChamber® (average ± standard deviation of 43.8 % ± 11.6 %), in relation to Volumatic® (p=0.351) or AeroChamber MAX® (p=0.115). The fine particle fraction reached values of 28.2 ± 4.1%, 29.6 ± 2.4% and 30.9 ± 6.7% for Volumatic®, AeroChamber MAX® and NebuChamber®, respectively. Conclusion: The spacers showed to have similar efficiencies in the delivery of salbutamol sulphate in the last stages, and there was no relation between the results and the spacers characteristics such as volume, shape and material. Therefore, Volumatic® appears to be perfect for hospital use, since its big volume does not constitute a disadvantage, and its lower cost, when compared to the remaining two spacers, represents an advantage of utmost importance for public hospital

    Surface photochemistry: photodegradation study of pyrene adsorbed onto microcrystalline cellulose and silica

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    Ground-state diffuse reflectance, time resolved laser-induced luminescence, diffuse reflectance laser flash-photolysis transient absorption and chromatographic techniques were used to elucidate the photodegradation processes of pyrene adsorbed onto microcrystalline cellulose and silica. Ground-state diffuse reflectance showed that on both substrates low concentrations display absorption of pyrene monomers. At high concentrations spectral changes attributed to aggregate formation were observed. Laser induced fluorescence showed that pyrene onto microcrystalline cellulose mainly presents fluorescence from monomers, while for silica, excimer-like emission was observed from low surface loadings (greater than or equal to 0.5 mumol g(-1)). Transient absorption and photodegradation studies were performed at concentrations where mainly monomers exist. On silica, pyrene presents transient absorption from its radical cation. On microcrystalline cellulose both radical cation, radical anion and pyrene triplet-triplet absorption were detected. Irradiation followed by chromatographic analysis showed that pyrene decomposes on both substrates. For pyrene on microcrystalline cellulose 1-hydroxypyrene was the main identified photoproduct since in the absence of oxygen further oxidation of 1-hydroxypyrene was very slow. For pyrene on silica photodegradation was very efficient. Almost no 1-hydroxypyrene was detected since in the presence of oxygen it is quickly oxidized to other photooxidation products. On both substrates, pyrene radical cation is the intermediate leading to photoproducts and oxygen it is not involved in its formation

    Concepção e desenvolvimento de sistemas biotecnológicos

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    In a simple and succinct form the authors intend to present the research and development activities that are being undertaken at the University of Minho in the area of biotechnology applied to the study, design, development and construction of equipment goods, which are being carried out together with important Iberian and European industrial companies. The projects are as follows: • Real time monitoring of beer fermentation using optical fiber sensors – MONI®TOR; • EggReady – Development of a prototype for a continuous industrial production of fried eggs, and • HealthyCream – Development of innovative dietetical solutions for the deli shop industry. These projects have been submitted and approved, and are all funded by the Portuguese National Strategic Reference Framework (QREN operational programmes 2007-2013). They are being developed with the following partner companies, all based in Portugal: UNICER Bebidas, S.A. – Innovation and Quality Department (Leça do Balio, Matosinhos); Derovo – Derivados de Ovos, S.A. (Pombal); Decorgel, S.A. (Trofa); Valinox – Indústrias Metalúrgicas, Lda. (Arouca), and the Departments of Biological Engineering (Braga) and Mechanical Engineering (Guimarães), School of Engineering, University of Minho.Pretende-se dar a conhecer, de uma forma simples e sucinta, os projectos de investigação e desenvolvimento que decorrem, actualmente, na Universidade do Minho, na área da biotecnologia aplicada ao estudo, concepção, projecto, desenvolvimento e construção de tecido industrial ibérico e europeu. Os projectos são: · Monitorização em tempo real da fermentação de cerveja na região do UV-Vis e IVPOC (SWNIR) com recurso a sondas de fibra óptica – MONI®TOR”; · EggReady - Protótipo para produção industrial, em contínuo, de ovos estrelados para consumo no canal HORECA, e · HealthyCream - Desenvolvimento de soluções dietéticas inovadoras para a indústria de pastelaria. Estes projectos foram submetidos e aprovados, sendo financiados pelo programa de incentivos do Quadro de Referência Estratégico Nacional Português, QREN (2007-2013). Estão a ser realizados em parceria com as empresas UNICER Bebidas, S.A. – Núcleo de Investigação e Desenvolvimento (Leça do Balio, Matosinhos); Derovo – Derivados de Ovos, S.A. (Pombal); Decorgel, S.A. (Trofa); Valinox – Indústrias Metalúrgicas, Lda. (Arouca), e os Departamentos de Engenharia Biológica (Braga) e Engenharia de Mecânica (Guimarães) da Escola de Engenharia da Universidade do Minho, todas estas instituições sediadas em Portugal

    Aligned carbon nanotube-based sensors for strain monitoring of composites

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    This paper presents a proof of concept of an aligned carbon nanotube (CNT) based strain sensor tested on the surface of a conventional aeronautic laminate. Two type of strain sensors were produced, type S and type T, in which the CNT alignment was parallel (Y) and transversal (X) to strain direction, respectively. Their electrical resistance response was thoroughly evaluated during cyclic tensile tests. Despite some disparities of the relative electrical resistance behavior in specific strain cycles, probably due to one-off interferences in the CNT conductive mechanism, the obtained gauge factor (GF) values were quite stable. Also, the electrical resistance anisotropy was evaluated and its opposite behavior when the samples were strained in Y- and X-directions may be used as strain direction indicator. Being able to quantify and indicate strain direction with just one 10 x 10 mm CNT patch, this sensor has proven to be suitable for strain sensing applications, namely for structure health monitoring of advanced composites.- Manuscript received March 4, 2021; revised March 25, 2021; accepted March 31, 2021. Date of publication April 5, 2021; date of current version June 30, 2021. This work was supported in part by the Project "Introduction of Advanced Materials Technologies Into New Product Development for the Mobility Industries-IAMAT," under the MIT-Portugal program exclusively financed by Fundacao para a Ciencia e Tecnologia "FCT" under Grant MITP-TB/PFM/0005/2013 and in part by the North Portugal Regional Operational Programme (NORTE 2020) under the Portugal 2020 Partnership Agreements through the European Regional Development Fund (ERDF) Project "Technologies for Sustainable and Smart Innovative Products (TSSiPRO)" under Grant NORTE-01-0145FEDER-000015. The associate editor coordinating the review of this article and approving it for publication was Dr. Cheng-Sheng Huang. (Corresponding author: Ana Raquel Santos.

    Study On The Optimization Of TheTextile Coloristic Performance Of The Bleaching Process Using Pad-Steam

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    Information concerning the critical variables of the bleaching process (transformation of a raw fabric into bleached) by pad-steam is scarce, since it is considered a recent process in the textile industry. One hundred percent fine cotton fabrics present great difficulties in the standardization of bleaching across different production batches, which is even more complex when the fabric composition provided by the supplier is unknown. Thus, one carried out an evaluation of the variables that influence color yield in the bleaching process by pad-steam. The conditions used consisted of the reintroduction of the process of desizing by pad-batch, as well as washing and bleaching by pad-steam. The other variable changed was the chemical recipes (desizing and bleaching). As result of this research, the variables which most influenced color performance were the degree of whiteness (Berger) and the pH of extraction. Hence, a change in the production process for this type of 100% fine cotton is required. In this work, a statistical control was performed on the characteristics of the product obtained, which compared results before and during the study. The suggestions for improvement, some of which have already been implemented, are also presented. The results were then compared, enabling one to observe a significant improvement.info:eu-repo/semantics/publishedVersio

    Build-Up an Economical Tool for Machining Operations Cost Estimation

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    Currently, there is a lack of affordable and simple tools for the estimation of these costs, especially for machining operations. This is particularly true for manufacturing SMEs, in which the cost estimation of machined parts is usually performed based only on required material for part production, or involves a time-consuming, non-standardized technical analysis. Therefore, a cost estimation tool was developed, based on the calculated machining times and amount of required material, based on the final drawing of the requested workpiece. The tool was developed primarily for milling machines, considering milling, drilling, and boring/threading operations. Regarding the considered materials, these were primarily aluminum alloys. However, some polymer materials were also considered. The tool first estimates the required time for total part production and then calculates the total cost. The total production time is estimated based on the required machining operations, as well as drawing, programming, and machine setup time. A part complexity level was also introduced, based on the number of details and operations required for each workpiece, which will inflate the estimated times. The estimation tool was tested in a company setting, comparing the estimated operation time values with the real ones, for a wide variety of parts of differing complexity. An average error of 14% for machining operation times was registered, which is quite satisfactory, as this time is the most impactful in terms of machining cost. However, there are still some problems regarding the accuracy in estimating finishing operation timesinfo:eu-repo/semantics/publishedVersio
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