Probing solute distribution and acid-base behaviour in water-in-oil microemulsions by fluorescence techniques

The distribution and acid-base behaviour of the four solutes harmine, chromotropic acid (4,5-dihydroxynaphthalene-2,7-disulfonate, disodium salt), 2-naphthol and 5,10,15,20-tetrakis [4-trimethylammonium)phenyl]-21H,23H-porphine tetra-p-tosylate (TTMP) have been studied in water-in-oil (w/o) microemulsions using fluorescence and absorption spectroscopy. Carbon tetrachloride is a quencher of fluorescence of these compounds, and studies using this as oil phase in microemulsions show that chromotropic acid is located in the water domain, TTMP at the surfactant-water interface, while the distribution of harmine or 2-naphthol depends on the degree of protonation. Detailed studies have been made on harmine. In water/AOT/cyclohexane microemulsions the cationic form is observed up to much higher apparent pH than in aqueous solutions. An important factor is shown to be the compartmentalisation of hydroxide ions between water pools. Similar effects are observed with the other probes, and it is suggested that compartmentalisation of hydrogen or hydroxide ions is a major effect in many acid-base reactions in microemulsions. The validity of the concept of pH in microemulsions under these conditions is questioned. Fluorescence lifetime measurements are also shown to provide information on the dynamics of the processes, and demonstrate the importance of diffusion of solutes from organic solvent to the microemulsion pool. A comparison is made of the behaviour of harmine in water/AOT/cyclohexane and water/lecithin/cyclohexane microemulsions.http://www.sciencedirect.com/science/article/B6TFR-416K8BS-12/1/1e48ace7f73afe3996e2e8a782a190d

Using Lanthanides as Probes for Polyelectrolyte-Metal Ion Interactions. Hydration Changes on Binding of Trivalent Cations to Nucleotides and Nucleic Acids

http://www.sciencedirect.com/science/article/B6TFM-4SWFNW8-1/1/aadd2972e76576ca7bf5c347abd5a68

Probing solute distribution and acid-base behaviour in water-in-oil microemulsions by fluorescence techniques

The distribution and acid-base behaviour of the four solutes harmine, chromotropic acid (4,5-dihydroxynaphthalene-2,7-disulfonate, disodium salt), 2-naphthol and 5,10,15,20-tetrakis [4-trimethylammonium)phenyl]-21H,23H-porphine tetra-p-tosylate (TTMP) have been studied in water-in-oil (w/o) microemulsions using fluorescence and absorption spectroscopy. Carbon tetrachloride is a quencher of fluorescence of these compounds, and studies using this as oil phase in microemulsions show that chromotropic acid is located in the water domain, TTMP at the surfactant-water interface, while the distribution of harmine or 2-naphthol depends on the degree of protonation. Detailed studies have been made on harmine. In water/AOT/cyclohexane microemulsions the cationic form is observed up to much higher apparent pH than in aqueous solutions. An important factor is shown to be the compartmentalisation of hydroxide ions between water pools. Similar effects are observed with the other probes, and it is suggested that compartmentalisation of hydrogen or hydroxide ions is a major effect in many acid-base reactions in microemulsions. The validity of the concept of pH in microemulsions under these conditions is questioned. Fluorescence lifetime measurements are also shown to provide information on the dynamics of the processes, and demonstrate the importance of diffusion of solutes from organic solvent to the microemulsion pool. A comparison is made of the behaviour of harmine in water/AOT/cyclohexane and water/lecithin/cyclohexane microemulsions.http://www.sciencedirect.com/science/article/B6TFR-416K8BS-12/1/1e48ace7f73afe3996e2e8a782a190d

Organic acids concentration in citrus juice from conventional versus organic farming

Every day consumers make choices about what to eat and ask themselves “Should I be buying organic food?” For producers, is very important to have technical information about the quality of organic products. It can facilitate to demonstrate the quality of organic products, in comparison with conventional ones. The purpose of our work was to compare internal and external characteristics of citrus, produced in organic versus conventional farming. The study was carried out in the south of Portugal. Fruits of different orchards have been harvested and submitted to physical and chemical analyses, as well as to a sensorial test. The analyses showed that the farming system affected fruit quality. Special attention was paid to the concentration of vitamin C, a compound which plays an important role in human health. Fruits from organic farming had a higher level of vitamin C, compared with fruits from conventional production. However, this result was not obtained in all cultivars. The concentration of other organic acids was also evaluated. Results showed clear differences between cultivars and between the two farming systems. In most cases, concentration of organic acids was higher in the citrus fruits from organic farming

β-Carbolines. 2. Rate Constants of Proton Transfer from Multiexponential Decays in the Lowest Singlet Excited State of Harmine in Water As a Function of pH

The β-carbolines present a complex problem involving multiple equilibria in the excited state in hydrogen-bonding solvents including water. Three excited state species exist: neutral, cation, and zwitterion. Here we examine the multiple equilibria and excited state kinetics of harmine, using time-resolved and steady state fluorescence techniques. From an analysis of the multiexponential decays, measured at the emission wavelengths of the three species as a function of the pH, seven unknowns (four rate constants and three reciprocal lifetimes) were determined. Data analysis was made both by a previously reported numerical method and by analytical solution of the differential equation set. The results obtained accurately describe the independently obtained steady-state fluorescence results. The dramatic modifications of the equilibria and rate constants between the ground and excited states can be understood on the basis of the significative changes in charge densities on the two nitrogen atoms of harmine upon excitation. Mechanisms are proposed for the formation of excited state cation and zwitterion beginning with the excited state neutral molecule

Insight into the sensing mechanism of an impedance based electronic tongue for honey botanic origin discrimination

Animpedance based electronictongue was developed and used to discriminate honey of different botanic origin. The e-tongue presented here is based on the small-signal frequency response of the electrical double-layer established between the honey solution and an array of four different sensing units composed by gold, carbon, indium-tin-oxide, and doped silicon. The ability of the e-tongue to discriminate honey of different floral origins was demonstrated by distinguishing honey from Bupleurum and Lavandula pollen prevalence. The honey fingerprint obtained with the e-tongue was validated by parallel melissopalenogical analysis and physico-chemical methods. It is demonstrated that the e-tongue is very sensitive to changes on the honey electrical conductivity. Small differences in electrical conductivity are introduced by the presence of ionisable organic acids and mineral salts. Moreover, we propose that the sensitivity of the tongue to changes in electrical conductivity can be explored to probe other complex liquid substances.We gratefully acknowledge financial support from the Portuguese Foundation for Science and Technology (FCT), the Instituto de Telecomunicações (UID/Multi/04326/2013), the Centro para os recursos biologicos e alimentos mediterranicos (UID/BIA/04325/2013) and the Centro de Estudos Florestais (UID/AGR/00239/2013).info:eu-repo/semantics/publishedVersio

The antibacterial, anti-biofilm, anti-inflammatory and virulence inhibition properties of Portuguese honeys

In Portugal, beekeeping activity has a significant weight among livestock production. The antimicrobial activities of Portuguese honeys have been reported, but the anti-biofilm formation and anti-virulence abilities have not been investigated. The main goal of this work was to study the impact of three monofloral honeys (citrus, lavender and strawberry tree) honeys on adherence of Staphylococcus aureus, methicillin-resistant S. aureus (MRSA) and Pseudomonas aeruginosa, as well as the influence of the same honeys on virulence using Galleria mellonella as a model. In addition, the general physico-chemical characterization of these honeys and the microbial quality were also performed. The anti-inflammatory activity was also estimated by analyzing the activity of the enzymes hyaluronidase and lipoxygenase. The tested honeys complied with European legislation and no microbial contamination was observed. Of all the honeys at 12.5 and 25%, w/v the citrus honey caused the highest inhibitory activity against P. aeruginosa. Strawberry tree honey at 25% w/v was able to significantly inhibit the MRSA strains. Anti-biofilm formation and anti-inflammatory activities were observed. The different honeys impaired the virulence of S. aureus and MRSA strains. The Portuguese honeys were capable of combating the tested bacterial pathogens not only by inhibiting their growth but also by affecting important pathogenicity properties, such as adherence and virulence

Applications of fractional calculus in electrical and computer engineering

Fractional Calculus (FC) goes back to the beginning of the theory of differential calculus. Nevertheless, the application of FC just emerged in the last two decades, due to the progress in the area of chaos that revealed subtle relationships with the FC concepts. In the field of dynamical systems theory some work has been carried out but the proposed models and algorithms are still in a preliminary stage of establishment. Having these ideas in mind, the paper discusses a FC perspective in the study of the dynamics and control of several systems. This article illustrates several applications of fractional calculus in science and engineering. It has been recognized the advantageous use of this mathematical tool in the modeling and control of many dynamical systems. In this perspective, this paper investigates the use of FC in the fields of controller tuning, electrical systems, digital circuit synthesis, evolutionary computing, redundant robots, legged robots, robotic manipulators, nonlinear friction and financial modeling.N/

Fractional order dynamical systems and its applications

This article illustrates several applications of fractional calculus (FC) in science and engineering. It has been recognized the advantageous use of this mathematical tool in the modeling and control of many dynamical systems. In this perspective, this paper investigates the use of FC in the following fields: Controller tuning; Electrical systems; Traffic systems; Digital circuit synthesis; Evolutionary computing; Redundant robots; Legged robots; Robotic manipulators; Nonlinear friction; Financial modeling.N/

SARS-CoV-2 introductions and early dynamics of the epidemic in Portugal

Genomic surveillance of SARS-CoV-2 in Portugal was rapidly implemented by the National Institute of Health in the early stages of the COVID-19 epidemic, in collaboration with more than 50 laboratories distributed nationwide. Methods By applying recent phylodynamic models that allow integration of individual-based travel history, we reconstructed and characterized the spatio-temporal dynamics of SARSCoV-2 introductions and early dissemination in Portugal. Results We detected at least 277 independent SARS-CoV-2 introductions, mostly from European countries (namely the United Kingdom, Spain, France, Italy, and Switzerland), which were consistent with the countries with the highest connectivity with Portugal. Although most introductions were estimated to have occurred during early March 2020, it is likely that SARS-CoV-2 was silently circulating in Portugal throughout February, before the first cases were confirmed. Conclusions Here we conclude that the earlier implementation of measures could have minimized the number of introductions and subsequent virus expansion in Portugal. This study lays the foundation for genomic epidemiology of SARS-CoV-2 in Portugal, and highlights the need for systematic and geographically-representative genomic surveillance.We gratefully acknowledge to Sara Hill and Nuno Faria (University of Oxford) and Joshua Quick and Nick Loman (University of Birmingham) for kindly providing us with the initial sets of Artic Network primers for NGS; Rafael Mamede (MRamirez team, IMM, Lisbon) for developing and sharing a bioinformatics script for sequence curation (https://github.com/rfm-targa/BioinfUtils); Philippe Lemey (KU Leuven) for providing guidance on the implementation of the phylodynamic models; Joshua L. Cherry (National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health) for providing guidance with the subsampling strategies; and all authors, originating and submitting laboratories who have contributed genome data on GISAID (https://www.gisaid.org/) on which part of this research is based. The opinions expressed in this article are those of the authors and do not reflect the view of the National Institutes of Health, the Department of Health and Human Services, or the United States government. This study is co-funded by Fundação para a Ciência e Tecnologia and Agência de Investigação Clínica e Inovação Biomédica (234_596874175) on behalf of the Research 4 COVID-19 call. Some infrastructural resources used in this study come from the GenomePT project (POCI-01-0145-FEDER-022184), supported by COMPETE 2020 - Operational Programme for Competitiveness and Internationalisation (POCI), Lisboa Portugal Regional Operational Programme (Lisboa2020), Algarve Portugal Regional Operational Programme (CRESC Algarve2020), under the PORTUGAL 2020 Partnership Agreement, through the European Regional Development Fund (ERDF), and by Fundação para a Ciência e a Tecnologia (FCT).info:eu-repo/semantics/publishedVersio