227 research outputs found

    A rare manifestation of neonatal alloimmune thrombocytopaenia

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    Neonatal alloimmune thrombocytopaenia (NAIT) results from a fetomaternal incompatibility with maternal sensitisation against a fetal human platelet antigen (HPA) and antibodies transfer to the fetal circulation, leading to platelet destruction. The clinical presentation is variable and isolated intraocular haemorrhage is rare. We present the case of a male newborn, with intrauterine growth restriction, born at 29 weeks due to pre-eclampsia. He presented proptosis of the left eye, hyphaema and elevated intraocular pressure, with no other signs of haemorrhage. Severe thrombocytopaenia was found (27×10(9)/L). Perinatal infection and maternal thrombocytopaenia were excluded. Positive anti-HPA-1a and antihuman leucocyte antigen class I alloantibodies were found in the mother. Platelet crossmatch between the father's platelets and mother's plasma was positive. Platelet transfusions and intravenous immunoglobulin were given with favourable response. This case highlights an unusual presentation of NAIT, which should be suspected in the presence of severe thrombocytopaenia in the first 24-72 h of life

    Influence of casting condition on the anisotropy of the fracture properties of Steel Fibre Reinforced Self-Compacting Concrete (SFRSCC)

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    Identification of the tensile constitutive behaviour of Fibre Reinforced Concrete (FRC) represents an important aspect of the design of structural elements using this material. Although an important step has been made with the introduction of guidance for the design with regular FRC in the recently published fib Model Code 2010, a better understanding of the behaviour of this material is still necessary, mainly for that with self-compacting properties. This work presents an experimental investigation employing Steel Fibre Self-Compacting Concrete (SFRSCC) to cast thin structural elements. A new test method is proposed for assessing the post-cracking behaviour and the results obtained with the proposed test method are compared with the ones resulted from the standard three-point bending tests (3PBT). Specimens extracted from a sandwich panel consisting of SFRSCC layers are also tested. The mechanical properties of SFRSCC are correlated to the fibre distribution by analysing the results obtained with the different tests. Finally, the stress-crack width constitutive law proposed by the fib Model Code 2010 is analysed in light of the experimental results.This work is part of the research project QREN number 5387, LEGOUSE, involving the companies Mota-Engil, CiviTest, the ISISE/University of Minho and PIEP. The first author would like to thank the FCT for the financial support through the PhD Grant SFRH/BD/64415/2009. The authors would like to express their sincere gratitude and appreciation to Ibermetais, Secil and SIKA, for supplying, respectively, the fibres, the cement and the super-plasticizer, respectively

    Reversed-phase chromatographic separation and downstream precipitation of lupane- and oleanane-type triterpenoids: experiments and modeling based on the method of moments

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    The reversed-phase chromatographic separation of two triterpenic acids (TTAs), betulinic and oleanolic acids, using a triacontyl (C30) stationary phase was addressed in this work. Methanol, water, acetonitrile, ethanol, isopropanol, ethyl acetate, acetone and mixtures thereof were tested, and the best mobile phase to conduct the separation was found to be methanol/acetonitrile 50/50 (%, v/v) at 23 °C, taking into account parameters like selectivity, resolution and TTAs solubility. The method of moments was used to determine the equilibrium constants of isotherms, the axial dispersion coefficients and the global linear driving force coefficients of pure betulinic and pure oleanolic acids. These parameters were then successfully validated by modeling unary and binary breakthrough curves. Simulated moving bed calculations showed that betulinic and oleanolic acids can be both obtained with purity of 99.2 % and productivity of 56.2 kg/(m3adsorbent day) using the packing material of an Acclaim C30 column with a 1-1-1-1 configuration with columns of 7.5 cm long. Finally, in order to recover the two TTAs from the SMB extract and raffinate streams, water was envisioned as a precipitation agent. Accordingly, the solubility of each TTA was measured in methanol/acetonitrile 70/30, 50/50, and 30/70 (%, v/v) modified with water. The obtained results showed that adding 65 % (%, v/v) of water it is possible to precipitate 98 % of the dissolved TTAs in all the tested methanol/acetonitrile mixtures.publishe

    Enhanced separation of bioactive triterpenic acids with a triacontylsilyl silica gel adsorbent: from impulse and breakthrough experiments to the design of a simulated moving bed unit

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    A simulated moving bed (SMB) unit was designed to separate oleanolic and ursolic acids, two naturally occurring triterpenoids with structural isomerism, with remarkable nutraceutical and pharmacological properties. A triacontylsilyl silica gel adsorbent (stationary phase of an Acclaim C30 column) was considered and impulse tests with different solvents were performed to select a mobile phase, from which methanol/water 95/5 (%, v/v) emerged as the most suitable. Equilibrium and global mass transport coefficients were then determined through breakthrough experiments using pure compound solutions and the C30 column. Afterwards, these parameters were applied to the simulation of two model binary mixture separations, whose breakthrough curves were also experimentally measured. Finally, the SMB unit was designed and optimized. It was demonstrated that using the packing of an Acclaim C30 column and methanol/water 95/5 (%, v/v) as mobile phase it is possible to separate both acids with purities of 99.9 wt.%, a productivity of 1.705 kg/(m3adsorbent day), and a configuration of two columns per section (2–2–2–2). The simulated results obtained in this work with the C30 stationary phase represent a significant improvement over literature data.publishe

    Thermal performance of resource-efficient geopolymeric mortars containing phase change materials

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    Energy efficiency is not only the most cost effective way to reduce emissions but also a way to improve competitiveness and create employment. This paper reports experimental results on the thermal performance of geopolymeric mortars containing different percentages of phase-change materials-PCMs. These materials have a twofold positive impact concerning eco-efficiency. On one hand, the mortars are based on industrial waste contributing for resource efficiency. And on the other hand, PCM based mortars have the capacity to enhance the thermal performance of the buildings. Five groups of alkali-activated based mortars with different PCM percentages were produced and placed on a panel within a small-scale prototype for thermal performance testing. The results show that the thermal conductivity of the mortars decreased with the increase in the percentage of the PCM. The results also show that the thermal performance of the PCM based mortars allowed for a stronger attenuation of the temperature amplitudes. Both for heating and cooling loads. The authors would like to acknowledge the financial support from the Foundation for Science and Technology (FCT) for the frame of research project with Ref. IF/00706/2014-UM.2.15 as well as C-TAC and ISISE research units.info:eu-repo/semantics/publishedVersio

    Railway bridge geometry assessment supported by cutting-edge reality capture technologies and 3D as-designed models

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    Documentation of structural visual inspections is necessary for its monitoring, maintenance, and decision about its rehabilitation, and structural strengthening. In recent times, close-range photogrammetry (CRP) based on unmanned aerial vehicles (UAVs) and terrestrial laser scanners (TLS) have greatly improved the survey phase. These technologies can be used independently or in combination to provide a 3D as-is image-based model of the railway bridge. In this study, TLS captured the side and bottom sections of the deck, while the CRP-based UAV captured the side and top sections of the deck, and the track. The combination of post-processing techniques enabled the merging of TLS and CRP models, resulting in the creation of an accurate 3D representation of the complete railway bridge deck. Additionally, a 3D as-designed model was developed based on the design plans of the bridge. The as-designed model is compared to the as-is model through a 3D digital registration. The comparison allows the detection of dimensional deviation and surface alignments. The results reveal slight deviations in the structural dimension with a global average value of 9 mm.The authors would like to thank the financial support from: Base Funding—UIDB/04708/ 2020 and Programmatic Funding—UIDP/04708/2020 of the CONSTRUCT—“Instituto de I&D em Estruturas e Construções, as well as ISISE (UIDB/04029/2020) and ARISE (LA/P/0112/2020)”—funded by national funds through the FCT/MCTES (PIDDAC). Additionally, the support by the doctoral grant UI/BD/150970/2021 (to Rafael Cabral)—Portuguese Science Foundation, FCT/MCTES. Furthermore, this work is framed within the project “Intelligent structural condition assessment of existing steel railway bridges” financed by the bilateral agreement FCT-NAWA (2022-23), as well as project “FERROVIA 4.0”, with reference to POCI-01-0247-FEDER-046111, co-funded by the European Regional Development Fund (ERDF), through the Operational Program for Competitiveness and Internationalization (COMPETE 2020) and the Lisbon Regional Operational Program (LISBOA 2020), under the PORTUGAL 2020 Partnership Agreement, as well as “NEXUS: Innovation Pact Digital and Green Transition—Transports, Logistics and Mobility”, nr. C645112083-00000059, investment project nr. 53, financed by the Recovery and Resilience Plan (PRR) and by European Union—NextGeneration EU

    New method for continuous monitoring of concrete E-modulus since casting

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    A new methodology that allows the continuous measurement of concrete E- modulus since casting is presented in this paper. This methodology is a variant to the classical resonant frequency methods, which have the downside of requiring concrete to be de-mouldable and withstand mechanical impact to start testing. The proposed experimental setup comprises a simply supported beam made-up with an acrylic tube, filled with the concrete to be tested, whose mid-span vertical accelerations induced just by ambient vibrations are continuously monitored by an accelerometer. The numerical treatment of the monitored accelerations allows identification of the 1st resonant frequency of the composite beam, which is evolving as concrete hardens. The E-modulus of concrete can thus be directly obtained from the monitored frequency. Besides the description of the overall setup, the results obtained in an experiment in which the concrete E-modulus was quantified also through static tests on the beam and via compressive tests in cylinders are presented and discussed. © 2010 Taylor & Francis Group, London

    Communication tools used by distributed teams in a BIM learning project

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    The constant changes in the world market demand flexible and fluid organizational structures, such as rotating and engaging human effort, to provide high performance. Therefore, organizations make use of distributed multicultural teams, meetings, and online lead projects. However, these social categorization processes can become a disadvantage if trigger potential conflicts during task performance. Distributed teams can also be difficult to manage, and their members can face extra adversities in communication. Architecture, Engineering and Construction Industry (AEC), is a context where the use of distributed teams is growing significantly, particularly through the enabling features of Building Information Modelling (BIM) methodologies. This paper was aimed at the diagnosis of communication behaviour in distributed teams in the context of a PBL methodology that requested students to work in distributed teams on two distinct locations. For that, the authors managed a workshop on Lean Project Management and Collaborative Tools in the European Master in Building Information Modelling (BIM A+) using a Lego for Scrum activity, adapted to a team of students distributed in Portugal and Slovenia. After that, nine distributed teams of students had to design exposition pavilions in BIM platform and using collaborative tools. At the end, each team had to present the project for the entire body of students and faculty, located in Guimaraes (Portugal) and Ljubljana (Slovenia).- (undefined
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