Does export intensity affect corporate leverage? Evidence from Portuguese SMEs

This paper examines the effect of export intensity on a firm's capital structure using a sample of 7,676 Portuguese SMEs. Results obtained from a system GMM estimation method show that the leverage ratio is negatively affected by export intensity. We document that firms with more growth opportunities have a higher leverage, while firms that have more profits, higher asset tangibility and face higher business risk have lower debt ratios. Our results also show that the implementation of governmental mechanisms that support export firms’ borrowing activities are critical in economies facing a financial crisisinfo:eu-repo/semantics/acceptedVersio

Lignin-enriched tricalcium phosphate/sodium alginate 3D scaffolds for application in bone tissue regeneration

The bone is a connective, vascularized, and mineralized tissue that confers protection to organs, and participates in the support and locomotion of the human body, maintenance of homeostasis, as well as in hematopoiesis. However, throughout the lifetime, bone defects may arise due to traumas (mechanical fractures), diseases, and/or aging, which when too extensive compromise the ability of the bone to self-regenerate. To surpass such clinical situation, different therapeutic approaches have been pursued. Rapid prototyping techniques using composite materials (consisting of ceramics and polymers) have been used to produce customized 3D structures with osteoinductive and osteoconductive properties. In order to reinforce the mechanical and osteogenic properties of these 3D structures, herein, a new 3D scaffold was produced through the layer-by-layer deposition of a tricalcium phosphate (TCP), sodium alginate (SA), and lignin (LG) mixture using the Fab@Home 3D-Plotter. Three different TCP/LG/SA formulations, LG/SA ratio 1:3, 1:2, or 1:1, were produced and subsequently evaluated to determine their suitability for bone regeneration. The physicochemical assays demonstrated that the LG inclusion improved the mechanical resistance of the scaffolds, particularly in the 1:2 ratio, since a 15 % increase in the mechanical strength was observed. Moreover, all TCP/LG/SA formulations showed an enhanced wettability and maintained their capacity to promote the osteoblasts' adhesion and proliferation as well as their bioactivity (formation of hydroxyapatite crystals). Such results support the LG inclusion and application in the development of 3D scaffolds aimed for bone regeneration.info:eu-repo/semantics/publishedVersio

Enantiomeric separation of tramadol and Its metabolites: method validation and application to environmental samples

The accurate assessment of racemic pharmaceuticals requires enantioselective analytical methods. This study presents the development and validation of an enantioselective liquid chromatography with a fluorescence detection method for the concomitant quantification of the enantiomers of tramadol and their metabolites, N-desmethyltramadol and O-desmethyltramadol, in wastewater samples. Optimized conditions were achieved using a Lux Cellulose-4 column 150 × 4.6 mm, 3 µm isocratic elution, and 0.1% diethylamine in hexane and ethanol (96:4, v/v) at 0.7 mL min−1. The samples were extracted using 150 mg Oasis® mixed-mode cation exchange (MCX) cartridges. The method was validated using a synthetic effluent of a laboratory-scale aerobic granular sludge sequencing batch reactor. The method demonstrated to be selective, accurate, and linear (r2 > 0.99) over the range of 56 ng L−1 to 392 ng L−1. The detection and the quantification limits of each enantiomer were 8 ng L−1 and 28 ng L−1 for tramadol and N-desmethyltramadol, and 20 ng L−1 and 56 ng L−1 for O-desmethyltramadol. The feasibility of the method was demonstrated in a screening study in influent and effluent samples from a wastewater treatment plant. The results demonstrated the occurrence of tramadol enantiomers up to 325.1 ng L−1 and 357.9 ng L−1, in the effluent and influent samples, respectively. Both metabolites were detected in influents and effluentsinfo:eu-repo/semantics/publishedVersio

Building on surface-active ionic liquids for the rescuing of the antimalarial drug chloroquine

Ionic liquids derived from classical antimalarials are emerging as a new approach towards the cost-effective rescuing of those drugs. Herein, we disclose novel surface-active ionic liquids derived from chloroquine and natural fatty acids whose antimalarial activity in vitro was found to be superior to that of the parent drug. The most potent ionic liquid was the laurate salt of chloroquine, which presented IC50 values of 4 and 110 nM against a chloroquine-sensitive and a chloroquine-resistant strain of Plasmodium falciparum, respectively, corresponding to an 11-and 6-fold increase in potency as compared to the reference chloroquine bisphosphate salt against the same strains. This unprecedented report opens new perspectives in both the fields of malaria chemotherapy and of surface-active ionic liquids derived from active pharmaceutical ingredients.publishersversionpublishe

Synchrotron X-ray studies on polyamide composites prepared by reactive injection molding

Semicrystalline polyamide 6 (PA6) and composites on its basis are among the most frequently used polymer materials for highly demanding applications. The performance of these composites depends on the crystalline structure of the PA6 matrix in which two crystalline forms most frequently coexist: α- and γ-polymorphs. This work reports on the crystalline structure of a variety of composite materials produced by in-mold reactive polymerization of caprolactam in specially designed semi-automatic equipment for reactive processing of nylons (NYRIM), carried out in the presence of particulate mineral reinforcements (natural or-ganically treated aluminum silicates and synthetic titanosilicates), PA6 oriented monofilaments and textile structures of glass fibers. The morphology and the crystalline structure of all composites were studied by syn-chrotron X-ray diffraction. Transcrystalline PA6 layer was observed in all fibrous PA6 laminates whose struc-ture fine crystalline structure was accessed.Fundação para a Ciência e Tecnologia; German Synchrotorn Radiation Source - DESY, Hambur

Colloidal nanomaterials for water quality improvement and monitoring

Water is the most important resource for all kind forms of live. It is a vital resource distributed unequally across different regions of the globe, with populations already living with water scarcity, a situation that is spreading due to the impact of climate change. The reversal of this tendency and the mitigation of its disastrous consequences is a global challenge posed to Humanity, with the scientific community assuming a major obligation for providing solutions based on scientific knowledge. This article reviews literature concerning the development of nanomaterials for water purification technologies, including collaborative scientific research carried out in our laboratory (nanoLAB@UA) framed by the general activities carried out at the CICECO-Aveiro Institute of Materials. Our research carried out in this specific context has been mainly focused on the synthesis and surface chemical modification of nanomaterials, typically of a colloidal nature, as well as on the evaluation of the relevant properties that arise from the envisaged applications of the materials. As such, the research reviewed here has been guided along three thematic lines: 1) magnetic nanosorbents for water treatment technologies, namely by using biocomposites and graphite-like nanoplatelets; 2) nanocomposites for photocatalysis (e.g., TiO2/Fe3O4 and POM supported graphene oxide photocatalysts; photoactive membranes) and 3) nanostructured substrates for contaminant detection using surface enhanced Raman scattering (SERS), namely polymers loaded with Ag/Au colloids and magneto-plasmonic nanostructures. This research is motivated by the firm believe that these nanomaterials have potential for contributing to the solution of environmental problems and, conversely, will not be part of the problem. Therefore, assessment of the impact of nanoengineered materials on eco-systems is important and research in this area has also been developed by collaborative projects involving experts in nanotoxicity. The above topics are reviewed here by presenting a brief conceptual framework together with illustrative case studies, in some cases with original research results, mainly focusing on the chemistry of the nanomaterials investigated for target applications. Finally, near-future developments in this research area are put in perspective, forecasting realistic solutions for the application of colloidal nanoparticles in water cleaning technologies.publishe

3D digital breast cancer models with multimodal fusion algorithms

Breast cancer image fusion consists of registering and visualizing different sets of a patient synchronized torso and radiological images into a 3D model. Breast spatial interpretation and visualization by the treating physician can be augmented with a patient-specific digital breast model that integrates radiological images. But the absence of a ground truth for a good correlation between surface and radiological information has impaired the development of potential clinical applications. A new image acquisition protocol was designed to acquire breast Magnetic Resonance Imaging (MRI) and 3D surface scan data with surface markers on the patient's breasts and torso. A patient-specific digital breast model integrating the real breast torso and the tumor location was created and validated with a MRI/3D surface scan fusion algorithm in 16 breast cancer patients. This protocol was used to quantify breast shape differences between different modalities, and to measure the target registration error of several variants of the MRI/3D scan fusion algorithm. The fusion of single breasts without the biomechanical model of pose transformation had acceptable registration errors and accurate tumor locations. The performance of the fusion algorithm was not affected by breast volume. Further research and virtual clinical interfaces could lead to fast integration of this fusion technology into clinical practice.publishersversionpublishe

New cholinesterase inhibitors for Alzheimer's disease: Structure Activity Studies (SARs) and molecular docking of isoquinolone and azepanone derivatives

A library of isoquinolinone and azepanone derivatives were screened for both acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) activity. The strategy adopted included (a) in vitro biological assays, against eel AChE (EeAChE) and equine serum BuChE (EqBuChE) in order to determine the compounds IC50 and their dose-response activity, consolidated by (b) molecular docking studies to evaluate the docking poses and interatomic interactions in the case of the hit compounds, validated by STD-NMR studies. Compound (1f) was identified as one of these hits with an IC50 of 89.5 mu M for EeAChE and 153.8 mu M for EqBuChE, (2a) was identified as a second hit with an IC50 of 108.4 mu M (EeAChE) and 277.8 mu M (EqBuChE). In order to gain insights into the binding mode and principle active site interactions of these molecules, (R)-(1f) along with 3 other analogues (also as the R-enantiomer) were docked into both RhAChE and hBuChE models. Galantamine was used as the benchmark. The docking study was validated by performing an STD-NMR study of (1f) with EeAChE using galantamine as the benchmark

A Cost-Effective Way To Expressively Increase the Blood-Stage Antimalarial Activity of Primaquine

Funding Information: The authors thank Fundação para a Ciência e Tecnologia (FCT, Portugal), for funding Research Units LAQV‐REQUIMTE (UIDB/50006/2020), CIQUP (UIDB/00081/2020), and GHTM (UID/Multi/04413/2013), and for project grant PTDC/BTM‐SAL/29786/2017. ATS thanks FCT and Sociedade Portuguesa de Química (SPQ, Portugal) for her doctoral grant SFRH/BD/150649/2020 Publisher Copyright: © 2021 Wiley-VCH GmbHInspired by previous disclosure of room-temperature ionic liquids derived from primaquine and cinnamic acids, which displayed slightly enhanced blood-stage activity compared to the parent drug, we have now combined this emblematic antimalarial with natural fatty acids. This affords surface-active ionic liquids whose liver-stage antiplasmodial activity is either retained or slightly enhanced, while revealing blood-stage antiplasmodial activity at least one order of magnitude higher than that of the parent compound. These findings open new perspectives towards the cost-effective recycling of classical drugs that are either shelved or in decline, and which is not limited to antimalarial agents.publishersversionpublishe