Browsing by Issue Date, starting with "2020-04"
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- Examining the meaning of luxury in tourism: a mixed-method approachPublication . Correia, Antónia; Kozak, Metin; Del Chiappa, GiacomoThis paper adopts a mixed method approach to examine antecedents and consequents of luxury tourism. Specifically, a structural model was proposed to depict what motivates tourists to make a luxury-driven tourism trip and what they expect from it. The antecedents and consequences of attitudes was then depicted through content analysis of 431 narratives. The study demonstrates that luxury has more a socially driven meaning than a self-constructed meaning, though narratives are more fluid on personal achievements. Regardless of the ambivalent nature of this concept, the defined traits of luxury tourism contribute to establishing a common set of practices to develop and make luxury intelligible.
- In vitro behaviour of konjac glucomannan microparticles aimed at pulmonary tuberculosis therapyPublication . Guerreiro, Filipa; Swedrowska, Magda; Rosa Da Costa, Ana; Grenha, Ana; Forbes, BenTuberculosis is one of the highest causes of death worldwide. Long periods of treatment are required and result in some cases in therapeutic incompliance, potentiating the development of multidrug-resistant tuberculosis. Thus, new approaches to treat the infection are required as an alternative to conventional orally administered treatment. This work proposes the development of an inhalable system, which is specifically targeted to alveolar macrophages, where the Mycobacterium tuberculosis is located. The targeting is mainly driven by the selected matrix material, konjac glucomannan (KGM), a natural polymer comprising mannan units that are expected to potentiate phagocytosis. Microparticles were loaded with two antitubercular drugs, isoniazid (INH) and rifabutin (RFB). KGM/INH/RFB microparticles were produced by spray-drying to produce particles with suitable characteristics to deliver INH and RFB to the alveolar region. The KGM/INH/RFB microparticles possessed an aerodynamic diameter of approximately 3 µm, meeting the requirement of a therapy targeted to alveolar macrophages. Moreover, KGM microparticles exhibited suitable geometric size (2.24 µm) and shape (spherical) to be phagocytosed to deliver drugs to infected macrophages. INH and RFB were associated with KGM microparticles with efficiencies of 91% and 74%, respectively. Similar in vitro release profiles were observed for both drugs in simulated lung fluid (SLF) replicating the lining fluid composition found in human alveoli.
- Sulphated locust bean gum-coated lipid nanocapsules as potential lung delivery carriersPublication . Pontes, Jorge Filipe; Braz, L.; Guerreiro, Filipa; Rosa Da Costa, Ana; Almouazen, Eyad; Lollo, Giovanna; Grenha, AnaDrugs pertaining to Biopharmaceutics Classification System (BCS) classes II and IV have limitations in their delivery, including in the lung. Therefore, drug delivery carriers have been proposed to improve the therapeutic effectiveness of such drugs. This work proposes lipid nanocapsules (LNC) as a potential platform for lung drug delivery. Locust bean gum (LBG), which is a galactomannan, was used as polymeric shell, protecting the oily core of the nanocapsules and providing their surface with hydrophilic character. Due to the neutral character of LBG, in order to enable nanocapsule formation, a sulphate derivative (LBGS) was prepared, which was confirmed by Fourier-transformed infrared (FTIR) spectroscopy. The electrostatic interaction between the negatively charged sulphate groups of LBGS and the positively charged groups of the used cationic lipid (1,2-dioleoyloxy-3- trimethylammoniumpropanchloride, DOTAP), allowed the formation of monodisperse nanocapsules, with sizes around 200 nm and strongly negative zeta potentials, between -70 and -85 mV. Envisaging potential lung drug delivery, the LBGS-coated LNC were co-formulated with mannitol using spray-drying, producing microencapsulated nanocapsules. Feret’s diameter was determined to be 2.6 ± 1.8 µm and 3.1 ± 1.9 µm for Man (control) and Man/LNC microparticles, respectively. Further studies are underway in order to optimise both the nanoplatform and the dry powder formulation.
- Analysis of quantum coherence in biologyPublication . Khmelinskii, Igor; Makarov, Vladimir, IWe reviewed the tools of quantum physics used in modeling of quantum coherence (QC) effects in different systems, including biological systems, which behave as quantum objects in some of their degrees of freedom. In particular, we considered the usage of the effective Hamiltonian (EH), Green's function (GF) and density matrix (DM) methods in the analysis of QC, focusing on QC in biological systems. We discussed the two main mechanisms of loss of quantum state coherence: (i) dephasing of the originally prepared coherent wave package and (ii) population relaxation in the same wave package. Dephasing does not affect the quantum state population, e.g. as in spin-spin relaxation, where dephasing is described by the tau(2) relaxation time. On the other hand, the state population relaxation of the spin wavepackage is attributed to spin-lattice relaxation and is described by the tau(1) relaxation time. Presently we discussed EH and GF formalisms in terms of the complex energy, dependent on intra- and intersystem interactions that induce state population relaxation. We provided a detailed analysis of these approaches for the exciton relaxation dynamics in a glycine polypeptide chain. The same phenomena were described in the DM formalism using the relaxation matrix. We discussed QC in different biological systems, showing that QC is conserved when the interactions of the coherent wavepackage with other degrees of freedom are weak, as otherwise population relaxation causes loss of QC. We believe that our results will be useful for the researchers in the area of quantum biology.
- Cartilage acidic protein 1 promotes increased cell viability, cell proliferation and energy metabolism in primary human dermal fibroblastsPublication . Letsiou, Sophia; Félix, Rute; Cardoso, João CR; L, Anjos; Mestre, Ana L G; H, Gomes; Power, DeborahCartilage acidic protein 1 (CRTAC1) is an extracellular matrix protein of human chondrogenic tissue that is also present in other vertebrates, non-vertebrate eukaryotes and in some prokaryotes. The function of CRTAC1 remains unknown but the protein's structure indicates a role in cell-cell or cell-matrix interactions and calcium-binding. The aim of the present study was to evaluate the in vitro effects of hCRTAC1-A on normal human dermal fibroblasts (NHDF). A battery of in vitro assays (biochemical and PCR), immunofluorescence and a biosensor approach were used to characterize the protein's biological activities on NHDF cells in a scratch assay. Gene expression analysis revealed that hCRTAC1-A protein is associated with altered levels of expression for genes involved in the processes of cell proliferation (CXCL12 and NOS2), cell migration (AQP3 and TNC), and extracellular matrix-ECM regeneration and remodeling (FMOD, TIMP1, FN1) indicating a role for hCRTAC1-A in promoting these activities in a scratch assay. In parallel, the candidate processes identified by differential gene transcription were substantiated and extended using Electric cell-substrate impedance sensing (ECIS) technology, immunofluorescence and cell viability assays. Our findings indicate that hCRTAC1-A stimulated cell proliferation, migration and ECM production in primary human fibroblasts in vitro. (C) 2020 Elsevier B.V. and Societe Francaise de Biochimie et Biologie Moleculaire (SFBBM). All rights reserved.
- The effect of dietary sericite on growth performance, digestive enzymes activity, gut microbiota and haematological parameters of Nile tilapia, Oreochromis niloticus (L.) fingerlingsPublication . Hassaan, Mohamed S.; Mohammady, Eman Y.; Soaudy, Mohamed R.; Palma, Jorge; Shawer, Ehab E.; El-Haroun, EhabA feeding trial was conducted to assess the effect of dietary supplementation of sericite (silicate clay) on growth performance, digestive enzymes activity, immune parameters and gut microbiota, of Nile tilapia, Oreochromis niloticus (L.) fingerlings. Five isonitrogenous diets were formulated each diet supplemented with different levels of sericite 0 (control), 2.5, 5, 7.5 and 10 g/kg diet. After 70 days of feeding trial, supplemental sericite were quadratically improved the final body weight (FBW) (P = 0.023), weight gain (WG) (P = 0.012), specific growth rate (SGR) (P = 0.023) and feed conversion ratio (FCR) P = 0.023) and protein efficiency ratio (PER) (quadratic, P = 0.045). However, the relationship between FCR and sericite levels was expressed by a broken-line model with an identified optimal breakpoint of 6.3 g/kg of sericite inclusion in the diets. Additionally, significant quadratic increase in alkaline phosphatase (ALP), amylase, trypsin, chymotrypsin and lipase enzymes were detected (P = 0.026; P = 0.023; P = 0.013; P = 0.045; P = 0.023) as the level of sericite increased in the diet. Furthermore, dietary sericite levels exhibited linear decreased in the total count bacteria, E. coli and Enterobacteriaceae of stomach and gut of experimental fish (linear, P = 0.032; P = 0.024; P = 0.035; P = 0.023; P = 0.012; P = 0.039, respectively). There was no effect of dietary sericite levels on hemoglobin (Hb), hematocrit (Htc) and red blood cells (RBCs), but a quadratic trend was observed in white blood cells (WBCs), monocytes and lymphocytes of fish (quadratic, P = 0.036; P = 0.013; P = 0.034), respectively. Increasing dietary sericite levels did not affect alanine aminotransferase (ALT), aspartate aminotransferase (AST), albumin and globulin but quadratically increased total protein (quadratic, P = 0.012) and IgM exhibited linear trend (linear, P = 0.045). Results in this study indicate that the addition of sericite as feed additive enhanced the growth, feed utilization, digestive enzyme activities, blood profile and gut biota of Nile tilapia.
- Manual de boas práticas de fruticultura - citrinosPublication . Duarte, AmilcarA adoção de boas práticas agrícolas contribui para a conservação do ambiente e para a produção de produtos agrícolas mais saudáveis. A certificação dessas boas práticas aumenta a confiança dos consumidores no produto e abre caminho à sua valorização ou, pelo menos, à melhoria do seu escoamento. Embora a implementação de algumas boas práticas acarrete um custo para o agricultor, a longo prazo, as boas práticas têm um elevado potencial para a melhorar o rendimento da exploração.
- Assessing cadmium-based quantum dots effect on the gonads of the marine mussel Mytilus galloprovincialisPublication . Gonçalves, Joanna M.; Rocha, Thiago Lopes; Nélia Mestre, N. C. Mestre, N. Mestre; Fonseca, T. G.; Bebianno, M.This study assesses the sex-specific effects induced by CdTe QDs, on the marine mussel Mytilus galloprovincialis in comparison to its dissolved counterpart. A 14 days exposure to CdTe QDs and dissolved Cd was conducted (10 mu g Cd L-1), analysing Cd accumulation, oxidative stress, biotransformation, metallothionein and oxidative damage in the gonads. Both Cd forms caused significant antioxidant alterations, whereby QDs were more pro-oxidant, leading to oxidative damage, being females more affected. Overall, biochemical impairments on gonads of M. galloprovincialis demonstrate that the reproductive toxicity induced by CdTe QDs in mussels are sex-dependent and mediated by oxidative stress and lipid peroxidation. It is crucial to acknowledge how gametes are affected by metal-based nanoparticles, such as Cd-based QDs. As well as understanding the potential changes they may undergo at the cellular level during gametogenesis, embryogenesis and larval development potentially leading to serious impacts on population sustainability and ecosystem health.
- Displacement-based seismic performance evaluation and vulnerability assessment of buildings: the N2 method revisitedPublication . Lopes, Gonçalo Correia; Vicente, Romeu; Ferreira, Tiago Miguel; Azenha, Miguel; Estêvão, João M. C.The so-called N2 method is a widely used nonlinear static method for the seismic design and/or assessment of different building typologies. In this paper, the idea of reversing the so-called N2 method currently adopted in the Annex B of Eurocode 8 (the code on which the present paper is based) in a direct displacement-based procedure is presented in a simple alternative format. In this way, it is possible to obtain the percentage of the seismic action associated to any performance displacement. By doing so, it is also possible to determine the target displacement without the need for an iterative procedure. The proposed method presents several advantages for professional engineering practice in respect to the seismic vulnerability assessment of new and existing buildings. The comparison of the original N2 method with the proposed one is illustrated by means of a test structure example.
- Symbolic computation applied to the study of the kernel of special classes of paired singular integral operatorsPublication . Conceição, Ana C.Operator theory has many applications in several main scientific research areas (structural mechan-ics, aeronautics, quantum mechanics, ecology, probability theory, electrical engineering, among others) and theimportance of its study is globally acknowledged. On the study of the operator’s kernel some progress has beenachieved for some specific classes of singular integral operators whose properties allow the use of particular strate-gies. However, the existing algorithms allow, in general, to study the dimension of the kernel of some classes ofsingular integral operators but are not designed to be implemented on a computer. The main goal of this paper is toshow how the symbolic and numeric capabilities of a computer algebra system can be used to study the kernel ofspecial classes of paired singular integral operators with essentially bounded coefficients defined on the unit circle.It is described how some factorization algorithms can be used to compute the dimension of the kernel of specialclasses of singular integral operators. The analytical algorithms [ADimKerPaired-Scalar], [AKerPaired-Scalar],and [ADimKerPaired-Matrix] are presented. The design of these new algorithms was focused on the possibility ofimplementing on a computer all the extensive symbolic and numeric calculations present in the algorithms. Forthe essentially bounded hermitian coefficients case, there exist some relations with Hankel operators. The papercontains some interesting and nontrivial examples obtained with the use of a computer algebra system.