Solid-phase microextraction for determination of 3-chloro-4-(dichloromethyl)-5-hydroxy-2[5H]-furanone in water

Solid-phase microextraction, using on-line bis(trimethylsilyl)trifluoroacetamide derivatisation, gas chromatography, and mass spectrometry, was evaluated in the quantification of 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX) in water samples. Fibres encompassing a wide range of polarities were used with headspace and direct immersion sampling. For the immersion procedure, various parameters affecting MX extraction, including pH, salinity, temperature, and extraction time were evaluated. The optimised method (polyacrylate fibre; 20% Na2SO4; pH 2.0; 60 min; 20 °C) was applied for reservoir chlorinated water samples-either natural or spiked with MX (50 ng L-1 and 100 ng L-1). The recovery of MX ranged from 44 to 72%. Quantification of MX in water samples was done using external standard and the selected ion monitoring mode. Correlation coefficient (0.98%), relative standard deviation (5%), limit of detection (30 ng L-1) and limit of quantification (50 ng L-1) were obtained from calibration curve.Microextração em fase sólida, usando a derivatização on-line com bis(trimetilsilil)trifluoroacetamida, cromatografia a gás e espectrometria de massas, foi avaliada para a quantificação de 3-cloro-4-(diclorometil)-5-hidróxi-2(5H)-furanona (MX) em amostras de água. Foram usadas fibras de diferentes polaridades empregando a amostragem por imersão e por headspace. Para o sistema de imersão, foram avaliados vários parâmetros que afetam a extração de MX, como pH, salinidade, temperatura e tempo de extração. O método otimizado (fibra de poliacrilato; 20% Na2SO4; pH 2,0; 60 min; 20 °C) foi aplicado para águas cloradas proveniente de reservatórios de abastecimento de água-amostras naturais e amostras com adição de MX (50 ng L-1 e 100 ng L-1). A recuperação de MX variou de 44 a 72%. A quantificação do MX em amostras de água foi feita por padrão externo empregando o modo de monitoramento de íon selecionado. O coeficiente de correlação (0,98%), o desvio padrão relativo (5%), o limite de detecção (30 ng L-1) e o limite de quantificação (50 ng L-1) foram obtidos a partir da curva analítica.FAPES

Unsupervised machine learning approaches to the qq-state Potts model

In this paper with study phase transitions of the $q$-state Potts model, through a number of unsupervised machine learning techniques, namely Principal Component Analysis (PCA), $k$-means clustering, Uniform Manifold Approximation and Projection (UMAP), and Topological Data Analysis (TDA). Even though in all cases we are able to retrieve the correct critical temperatures $T_c(q)$, for $q = 3, 4$ and $5$, results show that non-linear methods as UMAP and TDA are less dependent on finite size effects, while still being able to distinguish between first and second order phase transitions. This study may be considered as a benchmark for the use of different unsupervised machine learning algorithms in the investigation of phase transitions.Comment: Added computation of critical exponents; exposition improve

Voltammetric determination of sibutramine in beverages and in pharmaceutical formulations

A simple and sensitive method has been proposed for the determination of sibutramine-HCl in energy drinks, green tea and pharmaceutical formulations using differential pulse voltammetry performed on a hanging mercury drop electrode. In the chosen experimental condition (Mcllvaine pH 4.0 buffer, 50 mV pulse amplitude and 40 mV s-1 scan velocity), sibutramine-HCl presented a reversible behavior and a peak maximum at -80 mV. Detection limit was 0.4 mg L-1 and the working linear range extended up to 33.3 mg L-1 (r = 0.99). Analysis of real and fortified samples enabled recoveries between 91 and 102%. The electroanalytical method was compared with a HPLC method which indicated it accuracy

The db/db Mouse : a Useful Model for the Study of Diabetic Retinal Neurodegeneration

Background: To characterize the sequential events that are taking place in retinal neurodegeneration in a murine model of spontaneous type 2 diabetes (db/db mouse). Methods: C57BLKsJ-db/db mice were used as spontaneous type 2 diabetic animal model, and C57BLKsJ-db/+ mice served as the control group. To assess the chronological sequence of the abnormalities the analysis was performed at different ages (8, 16 and 24 weeks). The retinas were evaluated in terms of morphological and functional abnormalities [electroretinography (ERG)]. Histological markers of neurodegeneration (glial activation and apoptosis) were evaluated by immunohistochemistry. In addition glutamate levels and glutamate/aspartate transporter (GLAST) expression were assessed. Furthermore, to define gene expression changes associated with early diabetic retinopathy a transcriptome analyses was performed at 8 week. Furthermore, an additional interventional study to lower blood glucose levels was performed. Results: Glial activation was higher in diabetic than in non diabetic mice in all the stages (p<0.01). In addition, a progressive loss of ganglion cells and a significant reduction of neuroretinal thickness were also observed in diabetic mice. All these histological hallmarks of neurodegeneration were less pronounced at week 8 than at week 16 and 24. Significant ERG abnormalities were present in diabetic mice at weeks 16 and 24 but not at week 8. Moreover, we observed a progressive accumulation of glutamate in diabetic mice associated with an early downregulation of GLAST. Morphological and ERG abnormalities were abrogated by lowering blood glucose levels. Finally, a dysregulation of several genes related to neurotransmission and oxidative stress such as UCP2 were found at week 8. Conclusions: Our results suggest that db/db mouse reproduce the features of the neurodegenerative process that occurs in the human diabetic eye. Therefore, it seems an appropriate model for investigating the underlying mechanisms of diabetes-induced retinal neurodegeneration and for testing neuroprotective drugs

Psychometric properties of the modified Yale Food Addiction Scale 2.0 in a large Brazilian sample

Objective: The field of food addiction has attracted growing research attention. The modified Yale Food Addiction Scale 2.0 (mYFAS 2.0) is a screening tool based on DSM-5 criteria for substance use disorders. However, there is no validated instrument to assess food addiction. Methods: The mYFAS 2.0 has been transculturally adapted to Brazilian Portuguese. The data for this study was obtained through an anonymous web-based research platform: participants provided socio- demographic data and answered Brazilian versions of the the mYFAS 2.0 and the Barratt Impulsivity Scale (BIS-11). Analysis included an assessment of the Brazilian mYFAS 2.0’s internal consistency reliability, factor structure, and convergent validity in relation to BIS-11 scores. Results: Overall, 7,639 participants were included (71.3% females; age: 27.2 6 7.9 years). The Brazilian mYFAS 2.0 had adequate internal consistency reliability (Cronbach’s alpha = 0.89). A single factor solution yielded the best goodness-of-fit parameters for both the continuous and categorical version of the mYFAS 2.0 in confirmatory factor analysis. In addition, mYFAS 2.0 correlated with BIS-11 total scores (Spearman’s rho = 0.26, p o 0.001) and subscores. Conclusion: The Brazilian mYFAS 2.0 demonstrated adequate psychometric properties in our sample; however, future studies should further evaluate its discriminant validity

Synthesis and antimicrobial activity of a new class of azoimidazoles

The emergence of infectious diseases caused by new pathogens or multidrug-resistant (MDR) strains has been a global health threat over the last decades.1 These infections are among the most severe healthcare problems and have been associated to several deaths and heavy economic burden per year.2,3 The imidazole ring is present in several natural and synthetic molecules with biological activity namely on effective antimicrobial agents, which make it a vital anchor for the development of new therapeutic molecules in this field.4 Furthermore, amidrazones are known for their high reactivity thus being useful intermediates for the synthesis of compounds with a wide range of biological activities including antimicrobial. The amidrazone derivatives have been applied in different subjects of chemistry, specifically in the synthesis of azo molecules.5 In a previous work, novel imidazole-based 5-aminoimidazole-4-carboxamidrazones were prepared and exhibited potent antimicrobial activity against C. krusei and C. albicans.6 Further biological studies to elucidate the action mechanism revealed an interesting relationship between the antimicrobial activity and total intracellular ROS production by the yeasts.7 As these carboxamidrazones had previously evidenced a particular susceptibility to the presence of oxygen, all of these results combined prompted us to study the reactivity of 5-aminoimidazole-4-carboxamidrazones in the presence of different oxidant and antioxidant agents. Here, we present results of the electrochemical characterization by cyclic voltammetry to elucidate the oxidation mechanism of these compounds, and the results of the attempts performed to oxidize amidrazones in order to obtain the corresponding azoimidazoles. These products were fully characterized by NMR spectroscopy (including 1H RMN, D2O shake, 13C RMN, HMQC, HMBC and NOE techniques), mass spectroscopy, ATR-FTIR, melting point and elemental analysis. The antimicrobial activity of these new products has been also evaluated and highly promising results were obtained. All the results will be presented and discussed.Fundação para a Ciência e a Tecnologia (FCT) for financial support through the Chemistry Research Centre of the University of Minho (UID/QUI/00686/2020) and CIIMAR (UIBD/04423/2020). This work was also supported under the projects MEDCOR (PTDC/CTM-TEX/1213/2020) and UID/CTM/00264/2019, and the PhD grant SFRH/BD/137668/201

Synergistic activity of a novel class of azoimidazole dyes with polyvinylpyrrolidone-silver nanoparticles for the development of antibacterial textiles

The high demand for novel antimicrobial textiles by the medical, health care, hygiene, sportswear, personal protective equipment, and filtration sectors promoted the growth of functional textiles. However, the efficacy of antimicrobial agents against different pathogens is a considerable challenge due to the distinctive mechanisms of action and resistance. The development of novel synergistic antimicrobial agents may offer numerous opportunities to enhance antimicrobial effectiveness, namely boost the activity of individual agents, reduce dosages, minimize toxicity, and amplify the activity spectrum. On the one hand, azo dyes containing a heterocycle present good tinctorial strength and brightness of shades. In particular, the imidazole ring also has interesting antimicrobial, analgesic, and anti-inflammatory properties. On the other hand, silver nanoparticles (AgNPs) are renowned antimicrobial agents against a wide range of microorganisms, but their application is limited by the toxicity observed for effective concentrations. In this work, a novel class of azoimidazoles (AzoIz) and corresponding precursors (AmIz) were conjugated with polyvinylpyrrolidone-coated AgNPs, and their synergistic effect was assessed against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa. The results showed interesting antimicrobial properties of the novel AzoIz molecules when combined with a very small concentration of AgNPs. Thus, the application of these conjugates in textiles may lead to highly colored materials with remarkable antimicrobial properties, which worth to be further explored

Carbon and nitrogen isotope analysis: diet before and after the arrival of ceramic at Forte Marechal Luz Site

This study focused on carbon and nitrogen stable isotope analysisof dentin and enamel of individuals buried in pre-ceramic and ceramic layers ofthe Forte Marechal Luz site, located in the coast of Santa Catarina State, southernBrazil. The dentin collagen values indicate that the individuals had a proteindiet based mainly on marine resources during the formation period of theanalyzed teeth. However, there is a slight difference in the carbon results betweenthe individuals related to the pre-ceramic and the ceramic periods, suggesting thatthe latter inhabitants were consuming a little bit more resources like C3 plantsand terrestrial fauna than before, and therefore indicating that there was a greaterdiversification in the diet after the arrival of the ceramic in the region.Bioarchaeology; isotopic analysis, shell mounds, potteryNesse estudo foram realizadas análises de isótopos de carbono e nitrogênio de esmalte dentário e dentina de indivíduos sepultados em camadas sem e com cerâmica do sítio Forte Marechal Luz, localizado no litoral de Santa Catarina. Os resultados do colágeno da dentina sugerem que os indivíduos teriam uma dieta proteica rica em recursos marinhos durante o período de formação dos dentes analisados. No entanto, comparando períodos anteriores com posteriores à presença da cerâmica, observa-se uma leve tendência para resultados mais negativos no carbono nas camadas com cerâmica, indicando um maior consumo de recursos como plantas C3 e animais terrestres durante os períodos posteriores de ocupação do sítio e, consequentemente uma evidência de maior diversificação alimentar

High summer temperatures amplify functional differences between coral- and algae-dominated reef communities

Shifts from coral to algal dominance are expected to increase in tropical coral reefs as a result of anthropogenic disturbances. The consequences for key ecosystem functions such as primary productivity, calcification, and nutrient recycling are poorly understood, particularly under changing environmental conditions. We used a novel in situ incubation approach to compare functions of coral- and algae-dominated communities in the central Red Sea bimonthly over an entire year. In situ gross and net community primary productivity, calcification, dissolved organic carbon fluxes, dissolved inorganic nitrogen fluxes, and their respective activation energies were quantified to describe the effects of seasonal changes. Overall, coral-dominated communities exhibited 30% lower net productivity and 10 times higher calcification than algae-dominated communities. Estimated activation energies indicated a higher thermal sensitivity of coral-dominated communities. In these communities, net productivity and calcification were negatively correlated with temperature (>40% and >65% reduction, respectively, with +5 degrees C increase from winter to summer), whereas carbon losses via respiration and dissolved organic carbon release more than doubled at higher temperatures. In contrast, algae-dominated communities doubled net productivity in summer, while calcification and dissolved organic carbon fluxes were unaffected. These results suggest pronounced changes in community functioning associated with coral-algal phase shifts. Algae-dominated communities may outcompete coral-dominated communities because of their higher productivity and carbon retention to support fast biomass accumulation while compromising the formation of important reef framework structures. Higher temperatures likely amplify these functional differences, indicating a high vulnerability of ecosystem functions of coral-dominated communities to temperatures even below coral bleaching thresholds. Our results suggest that ocean warming may not only cause but also amplify coral-algal phase shifts in coral reefs.Peer reviewe

Food addiction: Prevalence, psychopathological correlates and associations with quality of life in a large sample

Objective: To determine the prevalence of food addiction in a large Brazilian non-clinical sample. Sociodemographic and psychopathological correlates of food addiction as well as associations with quality (QoL) domains were also investigated. Methods: This cross-sectional study obtained data from a Brazilian anonymous web-based research platform (N = 7639; 71.3% females). Participants provided sociodemographic data and completed the modified Yale Food Addiction Scale 2.0, PHQ-9, hypomania checklist (HCL-32), Fagerström Test for Nicotine Dependence, AUDIT, modified Skin picking-Stanford questionnaire, Minnesota impulsive disorders interview, Symptom Checklist-90-Revised inventory (SCL-90R), early trauma inventory self report-short form, and the WHO Quality of Life instrument-Abbreviated version (WHOQOL-Bref). Associations were adjusted to potential confounders through multivariable models. Results: The prevalence of food addiction was 4.32% (95%CI: 3.89-4.80%), and was more common among females. Food addiction was associated with a positive screen for a major depressive episode (OR = 4.41; 95%CI: 3.46-5.62), bipolar spectrum disorder (OR = 1.98; 95%CI: 1.43-2.75), and skin picking disorder (OR = 2.02; 95%CI: 1.31-3.09). Food addiction was also independently associated with exposure to early life psychological and sexual abuse (P = 0.008) as well as with reduced physical, psychological, social, and environment QoL (all P < 0.001). Conclusions: Food addiction may be common in low and middle-income countries, though possibly less prevalent than in the US. Food addiction was associated with co-occurring mood disorders and skin picking disorder as well as with early life psychological and sexual abuse. Finally, food addiction was independently associated with broad reductions in QoL. Public health efforts towards the early recognition and management of food addiction are warranted