Nanogravimetric study of lead underpotential deposition on selenium thin films as a semiconductor alloy formation procedure

An electrochemical quartz crystal microbalance Au electrode modified with a Se thin film was used to investigate the electrochemical behavior of lead ad-atoms using underpotential deposition (UPD) conditions. A specific quasi-reversible process was observed during the reduction of Pb2+ on Se thin films in perchloric acid media. The charge density of Pb ad-atoms on Se thin film (46.86 mu C cm(-2)) suggests a recovery of 0.1 monolayers, which is in good agreement with EQCM data. The Se thin film can be successfully alloyed with Pb atoms that are deposited by chronoamperometry using time intervals large enough to allow for diffusion toward the inner Se phase. Linear sweep voltammetry combined with EQCM in perchloric acid was used to characterize the amount of Pb absorbed in the Se thin film. These findings offer a new strategy for alloy formation in semiconductor films using UPD as an effective tool to quantify the exact amount of the incorporated metal2624982503CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPsem informação04/09906-

Design and Fabrication of Flexible Copper Sensor Decorated with Bismuth Micro/Nanodentrites to Detect Lead and Cadmium in Noninvasive Samples of Sweat

The use of economic methods to design and fabricate flexible copper sensors decorated with bismuth micro/nanodentrites for the detection of lead and cadmium in sweat is demonstrated. The flexible copper sensors were constructed with simple and cost-effective materials; namely, flexible and adhesive conductive copper tape, adhesive label containing the design of a three-electrode electrochemical system, and nail polish or spray as a protective layer. The flexible copper device consisted of a working electrode decorated with bismuth micro/nanodentrites using an electrodeposition technique, a copper pseudo-reference and copper counter electrodes. Under optimal experimental conditions, the flexible sensing platform showed excellent performance toward the detection of lead and cadmium using differential pulse anodic stripping voltammetry (DPAdSV) in a wide linear range from 2.0 μM to 50 μM with acceptable reproducibility and repeatability, and limits of detection and quantification of 5.36 and 17.9 μM for Cd2+ ions and 0.76 μM and 2.5 for Pb2+ ions. Studies of addition and recovery in spiked artificial sweat sample were performed, with a recovery of 104.6%. The flexible copper device provides a great opportunity for application in wearable perspiration-based healthcare systems or portable sensors to detect toxic metals in biological samples

Synthesis and characterization of 2D-carbonylated graphitic carbon nitride: A promising organic semiconductor for miniaturized sensing devices

Miniaturized chemical sensors are desirable for field analysis and screening trials aiming at point-of-care diagnostics. For this purpose, nanostructured materials, including those of the 2D family, are highly promising once they can add to sensing devices improved properties regarding sensitivity, the limit of detection, and portability. Here we report the synthesis, characterization, and application of 2D-carbonylated graphitic carbon nitride (c-g-C3N4) in the modification of screen-printed electrodes for photoelectrochemical analysis. Morphological and structural features of the material were studied through atomic force microscopy, scanning electronic microscopy, transmission electronic microscopy, X-ray diffraction, Fourier transformed-infrared spectrophotometry, and X-ray photoelectron spectroscopy. The optical bandgap of the semiconductor was estimated using diffuse reflectance spectrophotometry. Glucose determination was performed as proof of concept using c-g-C3N4 as support for the immobilization of glucose oxidase and application of the photoelectrochemical sensor. The device presented a linear range from 0 to 5.00 mmol L− 1 and a limit of detection of 0.43 mmol L− 1 . Our results indicate the suitability of employing c-g-C3N4 for designing photoelectrochemical sensors for detecting analytes of biological and medical interest

PtSnIr/C anode electrocatalysts: promoting effect in direct ethanol fuel cells

This study investigates the promoting effect of PtSnIr/C (1:1:1) electrocatalyst anode, prepared by polymeric precursor method, on the ethanol oxidation reaction in a direct ethanol fuel cell (DEFC). All of the materials used were 20% metal m/m on carbon. X-ray photoelectron spectroscopy (XPS) analysis showed the presence of Pt, PtOH2, PtO2, SnO2 and IrO2 at the electrocatalyst surface, indicating a possible decorated particle structure. X-ray diffractometry (XRD) analysis indicated metallic Pt and Ir as well as the formation of an alloy with Sn. Using the PtSnIr/C electrocatalyst prepared here with two times lower loading of Pt than PtSn/C E-tek electrocatalyst, it was possible to obtain the same maximum power density found for the commercial material. The main reaction product was acetic acid probably due to the presence of oxides, in this point the bifunctional mechanism is predominant, but an electronic effect should not be discarded

Factors influencing terrestriality in primates of the Americas and Madagascar

Among mammals, the order Primates is exceptional in having a high taxonomic richness in which the taxa are arboreal, semiterrestrial, or terrestrial. Although habitual terrestriality is pervasive among the apes and African and Asian monkeys (catarrhines), it is largely absent among monkeys of the Americas (platyrrhines), as well as galagos, lemurs, and lorises (strepsirrhines), which are mostly arboreal. Numerous ecological drivers and species-specific factors are suggested to set the conditions for an evolutionary shift from arboreality to terrestriality, and current environmental conditions may provide analogous scenarios to those transitional periods. Therefore, we investigated predominantly arboreal, diurnal primate genera from the Americas and Madagascar that lack fully terrestrial taxa, to determine whether ecological drivers (habitat canopy cover, predation risk, maximum temperature, precipitation, primate species richness, human population density, and distance to roads) or species-specific traits (body mass, group size, and degree of frugivory) associate with increased terrestriality. We collated 150,961 observation hours across 2,227 months from 47 species at 20 sites in Madagascar and 48 sites in the Americas. Multiple factors were associated with ground use in these otherwise arboreal species, including increased temperature, a decrease in canopy cover, a dietary shift away from frugivory, and larger group size. These factors mostly explain intraspecific differences in terrestriality. As humanity modifies habitats and causes climate change, our results suggest that species already inhabiting hot, sparsely canopied sites, and exhibiting more generalized diets, are more likely to shift toward greater ground use.Fil: Eppley, Timothy M.. San Diego Zoo Wildlife Alliance; Estados Unidos. Portland State University; Estados UnidosFil: Hoeks, Selwyn. Radboud Universiteit Nijmegen; Países BajosFil: Chapman, Colin A.. University of KwaZulu-Natal; Sudáfrica. Wilson Center; Estados Unidos. Northwest University; China. The George Washington University; Estados UnidosFil: Ganzhorn, Jörg U.. Universitat Hamburg; AlemaniaFil: Hall, Katie. Sedgwick County Zoo; Estados UnidosFil: Owen, Megan A.. San Diego Zoo Wildlife Alliance; Estados UnidosFil: Adams, Dara B.. Humboldt State University; Estados Unidos. Ohio State University; Estados UnidosFil: Allgas, Néstor. Asociación Neotropical Primate Conservation Perú; PerúFil: Amato, Katherine R.. Northwestern University; Estados UnidosFil: Andriamahaihavana, McAntonin. Université D'antananarivo; MadagascarFil: Aristizabal, John F.. Universidad Autónoma de Ciudad Juárez; México. Universidad de los Andes; ColombiaFil: Baden, Andrea L.. City University of New York; Estados Unidos. New York Consortium In Evolutionary Primatology; Estados UnidosFil: Balestri, Michela. Oxford Brookes University (oxford Brookes University);Fil: Barnett, Adrian A.. University Of Roehampton; Reino Unido. Universidade Federal de Pernambuco; BrasilFil: Bicca Marques, Júlio César. Pontificia Universidade Católica do Rio Grande do Sul; BrasilFil: Bowler, Mark. University Of Suffolk; Reino Unido. San Diego Zoo Wildlife Alliance; Estados UnidosFil: Boyle, Sarah A.. Rhodes College; Estados UnidosFil: Brown, Meredith. University of Calgary; CanadáFil: Caillaud, Damien. University of California at Davis; Estados UnidosFil: Calegaro Marques, Cláudia. Universidade Federal do Rio Grande do Sul; BrasilFil: Campbell, Christina J.. California State University Northridge (calif. State Univ. Northridge);Fil: Campera, Marco. Oxford Brookes University (oxford Brookes University);Fil: Campos, Fernando A.. University of Texas at San Antonio; Estados UnidosFil: Cardoso, Tatiane S.. Museu Paraense Emílio Goeldi; BrasilFil: Carretero Pinzón, Xyomara. Proyecto Zocay; ColombiaFil: Champion, Jane. University of Calgary; CanadáFil: Chaves, Óscar M.. Universidad de Costa Rica; Costa RicaFil: Chen Kraus, Chloe. University of Yale; Estados UnidosFil: Colquhoun, Ian C.. Western University; CanadáFil: Dean, Brittany. University of Calgary; CanadáFil: Kowalewski, Miguel Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales "Bernardino Rivadavia". Estación Biológica de Usos Múltiples (Sede Corrientes); Argentin

Associations of moderate to vigorous physical activity and sedentary behavior with depressive and anxiety symptoms in self-isolating people during the COVID-19 pandemic:A cross-sectional survey in Brazil

This is a cross-sectional study evaluating the associations of self-reported moderate to vigorous physical activity, and sedentary behavior with depressive, anxiety, and co-occurring depressive and anxiety symptoms (D&A) in self-isolating Brazilians during the COVID-19 pandemic. Depressive and anxiety symptoms were collected using the Beck Depression and Anxiety Inventories (BDI and BAI). Among the 937 participants (females=72.3%), those performing ≥30 min/day of moderate to vigorous or ≥15 min/day of vigorous physical activity had lower odds of prevalent depressive, anxiety, and co-occurring D&A symptoms. Those spending ≥10 h/day sedentary were more likely to have depressive symptoms.status: publishe

Effect of an edible nanomultilayer coating by electrostatic self-assembly on the shelf life of fresh-cut mangoes

This work aims at evaluating the effect of an alginate-chitosan nanomultilayer coating, obtained by electrostatic layer-by-layer self-assembling, in the quality and shelf life of fresh-cut mangoes. Coated and uncoated fresh-cut mangoes were stored under refrigeration (8 °C) for 14 days. The changes in mass loss, titratable acidity, pH, ascorbic acid content, total soluble solids, malondialdehyde content, browning rate, and microbial count were evaluated during storage. At the end of the storage period, lower values of mass loss, pH, malondialdehyde content, browning rate, soluble solids, microorganisms proliferation, and higher titratable acidity were observed in the coated mangoes. The nanomultilayer coating did not improve the retention of vitamin C during storage of fresh-cut mangoes. Results suggest that chitosan-alginate nanomultilayer edible coating extends the shelf life of fresh-cut mangoes up to 8 days.Author Marthyna Pessoa de Souza thanks Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES/PDEE-Brazil) and Fundacao de Amparo a Ciencia e Tecnologia do Estado de Pernambuco (FACEPE, Brazil) for granting her scholarships. The authors thank the Fundacao para a Ciencia e a Tecnologia (FCT) Strategic Project PEst-OE/EQB/LA0023/2013 and the Project "BioInd-Biotechnology and Bioengineering for improved Industrial and Agro-Food processes", REF. NORTE-07-0124-FEDER-000028, co-funded by the Programa Operacional Regional do Norte (ON.2-O Novo Norte), QREN, and FEDER (Portugal)

Does urbanization explain differences in interactions between an insect herbivore and its natural enemies and mutualists?

Urbanization can alter the composition of arthropod communities. However, little is known about how urbanization affects ecological interactions. Using experimental colonies of the black bean aphid Aphis fabae Scopoli reared on Vicia faba L, we asked if patterns of predator-prey, host-parasitoid and ant-aphid mutualisms varied along an urbanization gradient across a large town in southern England. We recorded the presence of naturally occurring predators, parasitoid wasps and mutualistic ants together with aphid abundance. We examined how biotic (green areas and plant richness) and abiotic features (impervious surfaces and distance to town center) affected (1) aphid colony size, (2) the likelihood of finding predators, mutualistic ants and aphid mummies (indicating the presence of parasitoids), and (3) how the interplay among these factors affected patterns of parasitoid attack, predator abundance, mutualistic interactions and aphid abundance. The best model to predict aphid abundance was the number of mutualistic ants attending the colonies. Aphid predators responded negatively to both the proportion of impervious surfaces and to the number of mutualistic ants farming the colonies, and positively to aphid population size, whereas parasitized aphids were found in colonies with higher numbers of aphids and ants. The number of mutualistic ants attending was positively associated with aphid colony size and negatively with the number of aphid predators. Our findings suggest that for insect-natural enemy interactions, urbanization may affect some groups, while not influencing others, and that local effects (mutualists, host plant presence) will also be key determinants of how urban ecological communities are formed