Abstract This paper documents an increase in the number of observed explosive cyclones (EC) at King George Island, South Shetland Islands, Antarctica, over the 1989‒2020 period. In ECs at 60o latitudes the surface atmospheric pressure drops ≥24 hPA in 24 hours. The annual EC frequency time series shows a significant positive trend of ~2.7 cyclones/decade, with a break in 2003 and average numbers of 7.3 and 11.8 events before and after that break, respectively. The increase follows closely earlier documented global sea surface temperature (SST) anomaly trends for the 1981‒2018 period, partially attributed to global warming and to the Pacific Decadal Oscillation (PDO). Connections between EC frequency and SST might occur through variations in SST in the southeastern Pacific and southwestern Atlantic, with anomalous cold conditions favoring an increase in ECs. We also found close relations between the number of ECs with simultaneous occurrences of PDO and Atlantic multidecadal oscillation in opposite phases, so that after 2003 they were in the cold and warm phases, respectively, and vice-versa before 2003. Both low-frequency modes seem to modulate the number of ECs. As per the authors knowledge these results have not been discussed before and may help climate modeling studies and weather forecasts.

Abstract This study aimed to optimize ultrasound-assisted palm oil-in-water nanoemulsions. The influence of hydrophilic-lipophilic balance (HLB), oil and surfactants concentrations, ultrasound intensity and processing time were investigated by means of two experimental designs. Desirability profiles were applied to detect the optimal conditions for preparing the nanoemulsion. Stable nanoemulsions with small droplet size and polydispersity index (PDI) were obtained at an HLB of 6.5, oil and surfactant concentrations of 2.8 wt%, ultrasound intensity of 200 W.cm-2 and processing time of 15 minutes. The nanoemulsion presented stability for 30 days at three different temperatures (4°C, 25°C and 40°C), which makes it suitable for application in the food and cosmetic industries. Ultrasound was shown to be a promising technology to produce nanoemulsions containing palm oil.

ABSTRACT A new modified electrode for indirect sensing of OH· and radical scavengers was described. The electrochemical polymerization of methylene blue in aqueous solutions and the properties of the resulting films on a glassy carbon electrode were carried out using cyclic voltammetry. A surface coverage of 1.11 × 109mol cm2 was obtained, revealing a complete surface coverage of the polymeric film on the electrode surface. OH· was able to destroy the poly(methylene blue) film by exposure to a Fenton solution. The loss of the electrochemical signal of the residual polymeric film attached to the electrode surface was related to the extent of its dissolution. The applicability of the sensor was demonstrated by evaluating the OH radical scavenging effect on different concentrations of ascorbic acid. The obtained radical scavenging capacity were 31.4%, 55.7%, 98.9% and 65.7% for the ascorbic acid concentrations of 5, 10, 30 and 50 mM, respectively.

ABSTRACT The phenolic content of the medicinal species Connarus perrottetti var. angustifolius Radlk., Connaraceae, Cecropia obtuse Trécul, Cecropia palmata Willd., Urticaceae; and Mansoa alliacea (Lam.) A.H.Gentry, Bignoniaceae, collected in three different years was evaluated. Plant infusions and hydroalcoholic, butanol and ethyl acetate extracts were analyzed by high-performance liquid chromatography with diode array detection. In order to endorse these results, analysis by electrospray mass spectrometry was also performed. Were identified: gallic acid, catechin, caffeic acid, ferulic acid, rutin, quercitrin and resveratrol. C. perrottetti showed greater diversity of polyphenols. M. alliacea had the higher concentration of caffeic acid even though it was found in all species. Catechin was the major antioxidant, but was not detected in M. alliacea. However, we discuss the popular use of these species, as well as their phenolic constitution and the interannual distribution of phenolic compounds.

A contaminação de pacientes com insuficiência renal por espécies metálicas pode estar associada a presença destes na medicação empregada durante o tratamento. Dentre os possíveis contaminantes estão metais nefrotóxicos tais como alumínio, cromo e níquel. No presente trabalho, a presença de Al, Cr e Ni como contaminantes em formulações de eritropoetina (EPO) foi investigada através da otimização de métodos analíticos empregando a voltamétria adsortiva de redissolucao catódica (AdCSV) associada a foto-decomposição de amostras com radiação UV. A irradiação UV de amostras acidificadas de EPO pelo período de 2 a 3 horas na presença de H2O2 possibilitou a decomposição eficiente da amostra e a determinação dos contaminantes por AdCSV sem a interferência da matriz. O método otimizado foi aplicado na determinação dos metais em formulações comerciais de EPO utilizadas rotineiramente no tratamento da anemia em pacientes com insuficiência renal crônica. Os níveis de contaminação encontrados nas amostras estudadas variaram de 420,2 a 840,5 ng mL-1 (RSD 2-5%) para o Al, de 12,0 a 40,0 ng mL-1 (RSD 2-6%) para o Cr e de 4,1 a 8,2 ng mL-1 (RSD 3-8%) para o Ni. Os resultados obtidos por AdCSV foram comparáveis aos obtidos por espectrometria de absorção atômica com atomização em forno de grafite (GFAAS). A contaminação de formulações EPO com Al, Cr e Ni mostrou ser uma fonte de contaminação importante para pacientes anêmicos com insuficiencia renal crônica.

The contamination of renal failure patients by metals can be associated to the presence of toxic metals in the medication, since they can be absorbed by the organism. Among the possible contaminants, there are nephrotoxic metals such as aluminum, chromium and nickel. In the present work, the presence of Al, Cr and Ni as contaminants in erythropoietin formulations (EPO) was investigated by optimizing the adsorptive cathodic stripping voltammetric (AdCSV) method and the photo-decomposition of samples by UV irradiation. The UV irradiation of acidified EPO samples from 2 to 3 h in the presence of H2O2 allowed the efficient sample decomposition and the determination of the contaminants by AdCSV without matrix interferences. The method was applied for the determination of the metals in commercial EPO formulations used routinely in the treatment of anemia in patients undergoing chronic renal failure. The contamination levels determined in the samples ranged from 420.2 to 840.5 ng mL-1 (RSD 2-5%) for Al, 12.0 to 40.0 ng mL-1 (RSD 2-6%) for Cr and 4.1 to 8.2 ng mL-1 (RSD 3-8%). The results obtained by AdCSV were in good agreement with those obtained by the comparative GFAAS measurements. The contamination of EPO formulations with Al, Cr and Ni was shown to be a serious contamination source for anemic patients undergoing chronic renal failure.

This work describes the optimization of pretreatment steps for the destruction of organic matter in samples of waters and biological fluids, by using an UV irradiation system with a high power UV radiation source (400 W). The efficiency of the system constructed for the photo-decomposition of samples of model waters, natural waters and biological fluids was investigated by performing recovery experiments of the metallic species Zn(II), Cd(II), Pb(II), Cu(II), Al(III) and Fe(III). The use of UV irradiation allowed the liberation of metals bound to the organic matrix and the determination of the total content of elements in the samples.