Solvability for a nonlinear coupled system of Kirchhoff type for the beam equations with nonlocal boundary conditions

In this paper, we investigate a mathematical model for a nonlinear coupled system of Kirchhoff type of beam equations with nonlocal boundary conditions. We establish existence, regularity and uniqueness of strong solutions. Furthermore, we prove the uniform rate of exponential decay. The uniform rate of polynomial decay is considered

Biological treatment of a contaminated gaseous emission from a paint and varnish plant—from laboratory studies to pilot-scale operation

A Vapour-Phase Bioreactor (VPB), namely a biotrickling filter, was scaled-up and operated in-situ for the treatment of gaseous emissions from a paint and varnish industrial plant. A microbial culture able to degrade the target compounds was enriched and a laboratory-scale VPB was established in order to evaluate the treatment's performance. The VPB presented removal efficiencies higher than 90% when exposed to Organic Loads (OL) of ca 50 g h−1 m−3 of reactor. The VPB was exposed to dynamic conditions often found in-situ (eg night and weekend shutdown periods) and showed a fast capacity to recover, with and without mineral medium recirculation. After a prolonged interruption period (10 months), the VPB was not able to cope with OL of ca 25 g h−1 m−3 of reactor and re-inoculation was required in order to recover the treatment performance. The VPB also showed limited treatment when exposed to higher OL (ca 500 g h−1 m−3 of reactor). The VPB was then scaled-up and a 3 m3 VPB was operated in-situ, showing removal efficiencies higher than 50% when exposed to an OL of c 5 g h−1 m−3 of reactor, thus complying with current legal demands. The addition of a maintenance feed was shown to be a useful tool for VPB pilot-scale operation when shutdown periods occurred. A factorial design of experiments was carried out, which allowed reduction to one-tenth of the initial supply of the main mineral medium constituents, namely phosphate buffer, ammonium and magnesium salts, and also elimination of the metal supplement. Overall, the VPBs were shown to be robust equipment, being able to respond actively to dynamic treatment scenarios, particularly night and weekend shutdown periods. Copyright © 2003 Society of Chemical Industr

A critical look at interpretation of electrochemical impedance spectra of sol-gel coated aluminium

A proper assignment of time constants is important for the correct interpretation of the electrochemical impedance spectra of coated substrates. In this work, several model aluminium samples with different anodic oxide thicknesses were prepared and characterised. The aluminium samples were coated by a hybrid sol-gel formulation and studied by electrochemical impedance spectroscopy (EIS) during immersion in NaCl solution. A hierarchical model containing three R-C elements adequately described the impedance spectra of the coated samples. The R-C elements described the properties of sol-gel coatings, aluminium oxide layers and corrosion process. The contribution of the aluminium oxide layer to impedance was unambiguously proven to be at middle frequencies on the spectra. Furthermore, the “real” capacitances of oxide layers were obtained from two capacitance–CPE equations and their applicability was scrutinized. The obtained results presented an opportunity to determine the adhesion behaviour of the sol-gel coatings to the oxide layers, which was studied by analysing the ratio of the oxide layer capacitance of the sol-gel coated samples to the capacitance of the uncoated ones. It was demonstrated that the exposed surface area of the oxide to the electrolyte was about 60–68% and was not changing during immersion. Based on these findings, a degradation model of the sol-gel coating on anodised aluminium was proposed.publishe

Contribution to the knowledge of bovine besnoitiosis in Portugal

Bovine besnoitiosis is a parasitic disease caused by the protozoa Besnoitia besnoiti (Marotel, 1912) that presents an acute phase (with fever and anasarca) and a chronic phase (with sclerodermitis), and has been characterized by high morbidity and low mortality (Ferreira, 1985). A study on the presence of besnoitiosis was carried out in October 2001 on a beef cattle herd located in the Évora region. On this farm, where previous cases of besnoitiosis were diagnosed, 12 assymptomatic Limousine bulls, aged between 18 and 24 months, were randomly selected and studied. Skin biopsies were collected and prepared. Subsequent histopathologic analyses of the biopsies have shown that 5 (42%) of the animals studied harboured B. besnoiti cysts. Therefore, these results demonstrate the immediate need to obtain insight in to some as yet not clearly defined aspects of the physiopathogeny of this disease. Possible ways of transmission (that is, determination of intermediate as well as definite hosts) and their impact on animal production such as bovine fertility and the quality of skins for leather industry should be addressed. In addition, the cases of assymptomatic animals with B. besnoiti in the Évora district should be clarified

Epidemiology and pathology of bovine schistosomiasis in Mozambique

AIM: To study the epidemiology and pathology of bovine schistosomiasis in Mozambique. BACKGROUND: - Bovine schistosomiasis is of great importance in Africa. It is caused by Schistosoma bovis; - In bovines the symptoms are similar to humans, mainly intestinal, hepato-splenic, vesical and genital; - It has been shown to be endemic through all Africa and in some Mediterranean countries (Portugal, Spain, Italy, Iraque and Israel); - Hybrids of S. haematobium and S. bovis are known to infect humans.N/

Graphene Oxide Thin Films with Drug Delivery Function

Funding Information: Funding: Funding was obtained through the Fundação para a Ciência e Tecnologia (FCT) through the projects iNOVA4Health, Translational Medicine program—UIDB/Multi/04462/2020; UIDB/50008/2020 and PTDC/CTM-REF/2679/2020.Graphene oxide has been used in different fields of nanomedicine as a manager of drug delivery due to its inherent physical and chemical properties that allow its use in thin films with biomedical applications. Several studies demonstrated its efficacy in the control of the amount and the timely delivery of drugs when it is incorporated in multilayer films. It has been demonstrated that oxide graphene layers are able to work as drug delivery or just to delay consecutive drug dosage, allowing the operation of time-controlled systems. This review presents the latest research developments of biomedical applications using graphene oxide as the main component of a drug delivery system, with focus on the production and characterization of films, in vitro and in vivo assays, main applications of graphene oxide biomedical devices, and its biocompatibility properties.publishersversionpublishe

Design of a nanostructured mucoadhesive system containing curcumin for buccal application : from physicochemical to biological aspects

Mucoadhesive nanostructured systems comprising poloxamer 407 and Carbopol 974P® have already demonstrated good mucoadhesion, as well as improved mechanical and rheological properties. Curcumin displays excellent biological activity, mainly in oral squamous cancer; however, its physicochemical characteristics hinder its application. Therefore, the aim of this study was to develop nanostructured formulations containing curcumin for oral cancer therapy. The photophysical interactions between curcumin and the formulations were elucidated by incorporation kinetics and location studies. They revealed that the drug was quickly incorporated and located in the hydrophobic portion of nanometer-sized polymeric micelles. Moreover, the systems displayed plastic behavior with rheopexy characteristics at 37 °C, viscoelastic properties and a gelation temperature of 36 °C, which ensures increased retention after application in the oral cavity. The mucoadhesion results confirmed the previous findings with the nanostructured systems showing a residence time of 20 min in porcine oral mucosa under flow system conditions. Curcumin was released after 8 h and could permeate through the porcine oral mucosa. Cytotoxicity testing revealed that the formulations were selective to cancer cells over healthy cells. Therefore, these systems could improve the physicochemical characteristics of curcumin by providing improved release and permeation, while selectivity targeting cancer cells

Valorisation of natural extracts from marine source focused on marine by-products: A review

The wide chemical and biological diversity observed in the marine environment makes the ocean an extraordinary source of high added value compounds (HAVC) which can be employed in many applications. Minerals, lipids, amino acids, polysaccharides and proteins from marine sources have unique features and, surprisingly, their highest concentration is often found in parts of marine organisms that are commonly discarded. Fish heads, viscera, skin, tails, offal and blood, as well as seafood shells possess several HAVC suitable for human health applications, yet most end up as residues throughout the raw material processing. This review updates information on this issue and conveys critical analysis of the chief methodologies to carry out extraction, purification and eventual transformation, with a focus on their actual and potential applications.info:eu-repo/semantics/publishedVersio