300 research outputs found

    Financial constraint and foreign direct investment of SMEs: evidence from Portugal

    Get PDF
    This work aims to explore the financing constraints perceived by Portuguese small and medium-sized enterprises (SMEs) carrying out productive foreign direct investment (FDI). It relies on primary data, presenting an explorative empirical analysis. The results evidence a strong dependence on internal funds and give little support to market failures in financing FDI, as no remarkable differences were found in financing constraints between domestic and foreign investments, but this reluctance of Portuguese SMEs towards external financing does not match with a willingness to open the social capital to new shareholders. Portuguese entrepreneurs lack knowledge of alternative financing sources to relieve dependence on domestic funds to FDI. Banks and government could relevantly contribute in this field, we also recommend further financial literacy in Portguese SMEs. This work is limited by its sample and qualitative nature. Although there is abundant literature on the access to economic agents' financing, to this day this work is the first to focus on Portuguese SMEs analysing primary data, hence its originality. Reporting SMEs’ reluctance towards external financing, it can enhance external financers to best capture such clients.Restricción financiera e inversión extranjera directa de las PYME: evidencia de PortugalEste trabajo intenta explorar las limitaciones de financiación percibidas por las pequeñas y medianas empresas (PYMES) portuguesas que realizan inversiones directas extranjeras (IED) productivas. Se basa en datos primarios y presenta un análisis empírico exploratorio. Los resultados demuestran una fuerte dependencia de los fondos internos y ligero énfasis en las deficiencias del mercado en la financiación de la IED, no reportando diferencias notables en las limitaciones de financiación entre las inversiones nacionales y extranjeras, pero esta renuencia de las PYMES portuguesas a la financiación externa no se corresponde con la voluntad de abrir el capital social a nuevos accionistas. Los empresarios portugueses no conocen alternativas para aliviar la dependencia de los fondos nacionales a la IED. Los bancos y el gobierno podrían contribuir en este campo, también recomendamos una mayor alfabetización financiera en las PYMES portuguesas. Este trabajo está limitado por su muestra y su naturaleza cualitativa. Aunque existe abundante literatura sobre el acceso a la financiación de los agentes económicos, hasta el día de hoy este trabajo es el primero que se centra en las PYMES portuguesas a través de datos primarios, de ahí su originalidad. Al informar sobre la reticencia de las PYMES a la financiación externa, puede mejorar la capacidad de los financiadores externos en captar esos clientes.

    Cleavage of DFNA5 by caspase-3 during apoptosis mediates progression to secondary necrotic/pyroptotic cell death.

    Get PDF
    Apoptosis is a genetically regulated cell suicide programme mediated by activation of the effector caspases 3, 6 and 7. If apoptotic cells are not scavenged, they progress to a lytic and inflammatory phase called secondary necrosis. The mechanism by which this occurs is unknown. Here we show that caspase-3 cleaves the GSDMD-related protein DFNA5 after Asp270 to generate a necrotic DFNA5-N fragment that targets the plasma membrane to induce secondary necrosis/pyroptosis. Cells that express DFNA5 progress to secondary necrosis, when stimulated with apoptotic triggers such as etoposide or vesicular stomatitis virus infection, but disassemble into small apoptotic bodies when DFNA5 is deleted. Our findings identify DFNA5 as a central molecule that regulates apoptotic cell disassembly and progression to secondary necrosis, and provide a molecular mechanism for secondary necrosis. Because DFNA5-induced secondary necrosis and GSDMD-induced pyroptosis are dependent on caspase activation, we propose that they are forms of programmed necrosis

    Blood flow in a bifurcation and confluence microchannel: effect of the cell-free layer in velocity profiles

    Get PDF
    A few detailed studies have been performed in complex in vitro microvascular networks composed by bifurcations and confluences. The main purpose of the present work is to numerically simulate the flow of two distinct fluids through bifurcation and confluence geometries, i. e red blood cells (RBCs)suspended in Dextran40 with about 14% of heamatocrit and pure water. The simulations of pure water and RBCs flows were performed resorting to the commercial finite volume software package FLUENT. A well known hemodynamic phenomenon, known as Fahraeus-Lindqvist effect, observed in both in vivo and in vitro studies, results in the formation of a marginal cell-free layer (CFL) at regions adjacent to the wall. Recently, studies have shown that the formation of the CFL is affected by the geometry of the microchannel and for the case of the confluences a CFL tend to appear in the middle of the microchannel after the apex of the confluence. By using the CFL experimental data, the main objective of this work is to implement a CFL in the numerical simulations in order to obtain a better understanding of the effect of this layer on the velocity profiles

    Flow of red blood cells in microchannel networks: in vitro studies

    Get PDF
    Human blood is a multiphase biofluid primarily composed by the deformable red blood cells (RBCs) suspended in plasma. Because the complex structure of RBCs, blood exhibits unique flow characteristics on micro-scale level, due to their complex biochemical mechanisms and their response to both shear and extensional flow, which influence the rheological properties and flow behaviour of blood [1,2]. In the past years in vitro blood studies have been extensively performed and some important physiological phenomena, such as Fahraeus and Fahraeus-Lindqvist effect, were revealed [1,3]. This pioneer studies performed by Fahraeus and Fahraeus-Lindqvist in straight glass microchannels [4] revealed that for narrow tubes (diameter<300 μm), the apparent viscosity of blood declines with decreasing diameter. More recently, due to the developments in microscopy, computers and image analysis techniques, several researchers have used new measuring methods to obtain deeper quantitative understanding of the blood flow dynamics, in vitro [5-8] and in vivo experiments [9-10]. The increasing interest by the microfluidic and biomedical communities has also played a key role in several recent developments of lab-on-chip devices for blood sampling, analysis and cell culturing, aimed in a near future, the development of blood diagnostic devices, as an alternative tool to the traditional diagnostic strategies. However, the blood flow in microvascular networks phenomena remains incompletely understood. Thus, it is important to investigate in detail the behaviour of RBCs flow occurring in a microchannel network, such as, with divergent and convergent bifurcations, which mimics the irregular vessel segments linked by numerous diverging and converging bifurcations. Previously, we made in vitro studies in microchannels with a simple divergent and convergent bifurcation, that showed a pronounced cell-free layer (CFL) immediately downstream of the apex of the convergent bifurcation [1,4]. This interesting result led us to the present work, where the CFL in a microchannel network is investigated by using a high-speed video microscopy system in order to further understand the blood flow behaviour in microvessels networks

    Biomechanical properties of breast tissue, a state-of-the-art review

    Get PDF
    This paper reviews the existing literature on the tests used to determine the mechanical properties of women breast tissues (fat, glandular and tumour tissue) as well as the different values of these properties. The knowledge of the mechanical properties of breast tissue is important for cancer detection, study and planning of surgical procedures such as surgical breast reconstruction using pre-surgical methods and improving the interpretation of clinical tests. Based on the data collected from the analysed studies, some important conclusions were achieved: (1) the Young’s modulus of breast tissues is highly dependent on the tissue preload compression level, and (2) the results of these studies clearly indicate a wide variation in moduli not only among different types of tissue but also within each type of tissue. These differences were most evident in normal fat and fibroglandular tissues

    Post-Synthesis Strategies to Prepare Mesostructured and Hierarchical Silicates for Liquid Phase Catalytic Epoxidation

    Get PDF
    Olefin epoxidation is an important transformation for the chemical valorization of olefins, which may derive from renewable sources or domestic/industrial waste. Different post-synthesis strategies were employed to introduce molybdenum species into mesostructured and hierarchical micro-mesoporous catalysts of the type TUD-1 and BEA, respectively, to confer epoxidation activity for the conversion of relatively bulky olefins (e.g., biobased methyl oleate, DL-limonene) to epoxide products, using tert-butyl hydroperoxide as an oxidant. The influences of (i) the type of metal precursor, (ii) type of post-synthesis impregnation method, (iii) type of support and (iv) top-down versus bottom-up synthesis methodologies were studied to achieve superior catalytic performances. Higher epoxidation activity was achieved for a material prepared via (post-synthesis) incipient wetness impregnation of MoO2(acac)2 (acac = acetylacetonate) on (pre-treated) siliceous TUD-1 and calcination; for example, methyl oleate was converted to the corresponding epoxide with 100% selectivity at 89% conversion (70 °C). Catalytic and solid-state characterization studies were conducted to shed light on material stability phenomena.publishe

    Visualization and measurement of red blood cells flowing in microfluidic devices

    Get PDF
    Several experimental techniques were performed in the past years using in vitro environments, in an attempt to not only understand the blood flow behaviour in microcirculation but also develop microfluidic devices as an alternative clinical methodology to detect blood diseases. Hence, the visualization and measurement of red blood cells (RBCs) flowing in a microfluidic device are important to provide not only essential information about hydrodynamic characteristics of the blood but also vital information to diagnose the initial symptoms of diseases during clinical investigations. For instance, RBC rigidity has been correlated with myocardial infarction, diabetes mellitus, hypertension, and also other haematological disorders and diseases that affect RBC deformation more directly, such as, hereditary spherocytosis, sickle cell anaemia and malaria. Regarding a better understanding of the RBCs deformation and motion, we present in this paper a compilation of studies made in our research group, using several microfluidic devices with different microchannel geometries and fabrication techniques (i.e., soft-lithography, xurography and hybrids) that focus in the shear and extensional flow behaviour, either in healthy or chemically stiffed RBCs.The authors acknowledge the financial support provided by 2007 Global COE Program “Global Nano-Biomedical Engineering Education and Research Network”, Japan and grant-in-Aid for Science and Technology, PTDC/SAU-BEB/105650/2008, PTDC/EME-MFE/099109/2008, PTDC/SAUENB/116929/2010, EXPL/EMS-SIS/2215/2013, scholarship SFRH/BD/91192/2012 and scholarship SFRH/BD/89077/2012 from FCT (Science and Technology Foundation), COMPETE, QREN and European Union (FEDER). The authors are also very grateful to Dr. Mónica Oliveira (Strathclyde University), Professor Takuji Ishikawa and Professor Takami Yamaguchi (Tohoku University) for their suggestions and support to this research work

    1,3-Dicyclo­hexyl­imidazolidine-2,4,5-trione

    Get PDF
    The title compound, C15H22N2O3, has been isolated as a by-product of an oxidative cleavage of the C—C bond linking two five-membered rings of 1,3-dicyclo­hexyl-5-(3-oxo-2,3-dihydro­benzofuran-2-yl)imidazolidine-2,4-dione. Individual mol­ecular units are engaged in weak C=O⋯C=O inter­actions [O⋯C = 2.814 (10) and 2.871 (11) Å], leading to the formation of supra­molecular chains which close pack, mediated by van der Waals contacts, in the bc plane

    Análise do escoamento sanguíneo em microcanais com bifurcações

    Get PDF
    In vitro experiments allow precise measurement and control over relevant physiological variables. Thus, in the present study we have used a lithography technique to fabricate a rectangular PDMS microchannel with a bifurcation. By using a confocal micro-PTV system, we have measured the effect of bifurcation on the flow behaviour of both fluorescent particles diluted in pure water and red blood cells (RBCs) in concentrated suspensions. After performing simulations with the commercial finite element software package POLYFLOW®, some experimental results were compared with the numerical results. Our preliminary results suggest that the RBC paths may suffer fluctuations on the transversal direction caused by RBCs obstruction around the neighbourhood of the diverging point of the bifurcation

    Torulaspora delbrueckii phenotypic and metabolic profiling towards its biotechnological exploitation

    Get PDF
    Wine is a particularly complex beverage resulting from the combination of several factors, with yeasts being highlighted due to their fundamental role in its development. For many years, non-Saccharomyces yeasts were believed to be sources of spoilage and contamination, but this idea was challenged, and many of these yeasts are starting to be explored for their beneficial input to wine character. Among this group, Torulaspora delbrueckii is gaining relevance within the wine industry, owing to its low volatile acidity production, increased release of aromatic compounds and enhanced color intensity. In addition, this yeast was also attracting interest in other biotechnological areas, such as bread and beer fermentation. In this work, a set of 40 T. delbrueckii strains, of varied geographical and technological origins, was gathered in order to characterize the phenotypic behavior of this species, focusing on different parameters of biotechnological interest. The fermentative performance of the strains was also evaluated through individual fermentations in synthetic grape must with the isolates’ metabolic profile being assessed by HPLC. Data analysis revealed that T. delbrueckii growth is significantly affected by high temperature (37 °C) and ethanol concentrations (up to 18%), alongside 1.5 mM SO2, showing variable fermentative power and yields. Our computation models suggest that the technological origin of the strains seems to prevail over the geographical origin as regards the influence on yeast properties. The inter-strain variability and profile of the products through the fermentative processes reinforce the potential of T. delbrueckii from a biotechnological point of view.This work was supported by the UID/BIA/04050/2013 (POCI-01-0145-FEDER-007569) and UID/BIA/04050/2019 strategic programs and by the project PTDC/BIA-MIC/32059/2017, which is funded by national funds through the FCT-Fundação para a Ciência e Tecnologia and by the ERDFEuropean Regional Development Fund through the COMPETE2020–Programa Operacional Competitividade e Internacionalização (POCI) and Sistema de Apoio à Investigação Científica e Tecnológica (SAICT). FS-S and TF were supported by Fellowships (UI/BD/150873/2021 and 2021.04595.BD, respectively) from Fundação para a Ciência e Tecnologia, Portugal
    corecore