Herein we investigate the effect of irreversibly adsorbed bismuth on polycrystalline platinum (Pt p) on the electrooxidation of glycerol in alkaline media by combining electrochemical, spectroscopic (in situ FTIR) and analytical (HPLC on line) techniques. We found that the activity of Pt p increases by about fivefold when the optimal quantity of Bi ions is added to the solution. Besides, the adatom strongly impacts the reaction products by suppressing the pathways with CC bond breaking, hindering the formation of CO (and other unknown intermediates) and enhancing the production of Glycerate. Different to the results in acid media for Pt p-Bi systems where Bi block the oxidation pathway through the primary carbon, glycerate is the main product in alkaline media and dihydroxyacetone is either produced in extremely low quantities or not produced. Besides, comparing our results with those in acid media, the peak current recorded at 1 mV.s-1 in this work was one order of magnitude higher. These results show the strong impact of the pH in the reaction rate and selectivity.

The Neotropical poison frog genus Ranitomeya is revised, resulting in one new genus, one new species, five synonymies and one species classified as nomen dubium. We present an expanded molecular phylogeny that contains 235 terminals, 104 of which are new to this study. Notable additions to this phylogeny include seven of the 12 species in the minuta group, 15 Ranitomeya amazonica, 20 R. lamasi, two R. sirensis, 30 R. ventrimaculata and seven R. uakarii. Previous researchers have long recognized two distinct, reciprocally monophyletic species groups contained within Ranitomeya, sensu Grant et al. 2006: the ventrimaculata group, which is distributed throughout much of the Amazon, and the minuta group of the northern Andes and Central America. We restrict Ranitomeya to the former group and erect a new genus, Andinobates Twomey, Brown, Amézquita & Mejía-Vargas gen. nov., for members of the minuta group. Other major taxonomic results of the current revision include the following: (i) A new species, Ranitomeya toraro Brown, Caldwell, Twomey, Melo-Sampaio & Souza sp. nov., is described from western Brazil. This species has long been referred to as R. ventrimaculata but new morphological and phylogenetic data place it sister to R. defleri. (ii) Examination of the holotype of R. ventrimaculata revealed that this specimen is in fact a member of what is currently referred to as R. duellmani, therefore, Dendrobates duellmani Schulte 1999 is considered herein a junior synonym of D. ventrimaculatus Shreve 1935 (= R. ventrimaculata). (iii) For the frogs that were being called R. ventrimaculata prior to this revision, the oldest available and therefore applicable name is R. variabilis. Whereas previous definitions of R. variabilis were restricted to spotted highland frogs near Tarapoto, Peru, our data suggest that this color morph is conspecific with lowland striped counterparts. Therefore, the definition of R. variabilis is greatly expanded to include most frogs which were (prior to this revision) referred to as R. ventrimaculata. (iv) Phylogenetic and bioacoustic evidence support the retention of R. amazonica as a valid species related to R. variabilis as defined in this paper. Based on phylogenetic data, R. amazonica appears to be distributed throughout much of the lower Amazon, as far east as French Guiana and the Amazon Delta and as far west as Iquitos, Peru. (v) Behavioral and morphological data, as well as phylogenetic data which includes topotypic material of R. sirensis and numerous samples of R. lamasi, suggest that the names sirensis, lamasi and biolat are applicable to a single, widespread species that displays considerable morphological variation throughout its range. The oldest available name for this group is sirensis Aichinger; therefore, we expand the definition of R. sirensis. (vi) Ranitomeya ignea and R. intermedia, elevated to the species status in a previous revision, are placed as junior synonyms of R. reticulata and R. imitator, respectively. (vii) Ranitomeya rubrocephala is designated as nomen dubium. In addition to taxonomic changes, this revision includes the following: (i) Explicit definitions of species groups that are consistent with our proposed taxonomy. (ii) A comprehensive dichotomous key for identification of ‘small’ aposematic poison frogs of South and Central America. (iii) Detailed distribution maps of all Ranitomeya species, including unpublished localities for most species. In some cases, these records result in substantial range extensions (e.g., R. uakarii, R. fantastica). (iv) Tadpole descriptions for R. amazonica, R. flavovittata, R. imitator, R. toraro sp. nov., R. uakarii and R. variabilis; plus a summary of tadpole morphological data for Andinobates and Ranitomeya species. (v) A summary of call data on most members of Andinobates and Ranitomeya, including call data of several species that have not been published before. (vi) A discussion on the continued impacts of the pet trade on poison frogs (vii) A discussion on several cases of potential Müllerian mimicry within the genus Ranitomeya. We also give opinions regarding the current debate on recent taxonomic changes and the use of the name Ranitomeya.

Herein we investigated the effect of the adsorption of Bi and Pb on polycrystalline platinum (Pt p ) on the electrooxidation of glycerol (EOG) in alkaline media by combining electrochemical, spectroscopic (in situ FTIR), and analytical (online HPLC) techniques. Besides, we used single crystal Pt electrodes to understand the effect of the modification of Pt p in terms of the atomic arrangements on its surface. We found that the activity of Pt p increases in the presence of Pb (Pt p −Pb), which acts by suppressing the pathways with complete CC bond breaking (to produce carbonate) and enhancing the production of glycerate, formate, tartronate, and glycolate. We also found that Pt(100) and Pt(111) are affected by the adsorption of both adatoms. However, the modification of Pt(110) explains the results obtained with Pt p . This basal plane is highly activated by Bi and Pb and its behavior is similar to those of Pt p −Bi and Pt p −Pb, respectively. These results permit the conclusion that the adatoms acts mainly by activating Pt atoms with low coordination, which generally binds the adsorbates more strongly and, in consequence, suffers more from poisoning. The adatoms act by preventing the formation of multiple bonded intermediates, likely through a combination of a third body effect and also to a change in the electronic configuration at the surface of the catalyst. We propose in this work that the higher promotion of the EOG by the adatoms in alkaline media is due to a stabilization of the negatively charged intermediates by the Coulombic interaction with the positively charged adatoms.

Genetic divergence and speciation mechanisms of the Amazonian Engystomops frog have been inferred mainly from mtDNA sequences, microsatellite and male advertisement call. Although many aspects of this divergence remain unclear, cytogenetic analyses of Amazonian Engystomops populations are described and are compared to the relationships inferred from mitochondrial and nuclear DNA sequence data. High cytogenetic variation distinguished karyotypic patterns among the populations, even between populations which had no prezygotic isolation previously inferred from mating call analysis. Interestingly, the Puyo and Acre populations, which are in different clades, showed heteromorphic sex chromosomes (XX/XY), not identified in the other Ecuatorian populations analyzed. The analysis of a specimen collected in a site near Yasuní (Ecuador) which was cytogenetically related to the specimens from Puyo (Ecuador), was also phylogenetically closely related these specimens. In the rhodopsin nucleotide sequences, six polymorphic sites were identified and various specimens were heterozygous for them. All the data presented herein, in conjunction with those previously reported, corroborate the hypothesis that Engystomops petersi is a complex of distinct species. It also indicates that karyotypic evolution patterns may have played a substantial role in the Engystomops speciation and the occurrence of sporadic mating events between divergent evolutive lineages is discussed.

This study assessed oral health outcomes (perceived dental treatment need, untreated dental caries, gingival bleeding, periodontal pockets, and pain in teeth and gums), in relation to color/race inequalities among adolescents in each Brazilian region. The database included dental examination and interview of 16,833 15-19-year-old adolescents, surveyed by the Brazilian health authority, from May 2002 to October 2003, in accordance with international diagnostic criteria standardized by the World Health Organization. Prevalence ratios estimated by Poisson regression, and controlled by socioeconomic status and access to fluoridated piped water, assessed oral health differentials among color/race groups and country's regions. Except for periodontal pockets, prevalence figures were higher in the North and Northeast: perceived dental treatment needs, untreated dental caries, gingival bleeding at probing and pain in teeth and gums varied between 80-83%, 75-76%, 38-43%, and 17-18%, respectively, in these regions. Adolescents living in the Southeast - the richest Brazilian region - presented a better general profile of oral health than their counterparts living in the remaining regions; they had a lower prevalence of untreated dental caries (54%) and unfavorable gingival status (29%). However, the Southeast presented color/race inequalities in all oral health outcomes, with a poorer profile systematically affecting browns or blacks, depending on the oral health condition under consideration. These results reinforce the need for expanding the amplitude of health initiatives aimed at adolescent oral health. Socially appropriate health programs should concurrently aim at the reduction of levels of oral disease and its inequalities.