The Role of Cation Acidity on the Competition between Hydrogen Evolution and CO2 Reduction on Gold Electrodes

CO2 electroreduction (CO2RR) is a sustainable alternative for producing fuels and chemicals. Metal cations in the electrolyte have a strong impact on the reaction, but mainly alkali species have been studied in detail. In this work, we elucidate how multivalent cations (Li+, Cs+, Be2+, Mg2+, Ca2+, Ba2+, Al3+, Nd3+, and Ce3+) affect CO2RR and the competing hydrogen evolution by studying these reactions on polycrystalline gold at pH = 3. We observe that cations have no effect on proton reduction at low overpotentials, but at alkaline surface pH acidic cations undergo hydrolysis, generating a second proton reduction regime. The activity and onset for the water reduction reaction correlate with cation acidity, with weakly hydrated trivalent species leading to the highest activity. Acidic cations only favor CO2RR at low overpotentials and in acidic media. At high overpotentials, the activity for CO increases in the order Ca2+ < Li+ < Ba2+ < Cs+. To favor this reaction there must be an interplay between cation stabilization of the*CO2- intermediate, cation accumulation at the outer Helmholtz plane (OHP), and activity for water reduction. Ab initio molecular dynamics simulations with explicit electric field show that nonacidic cations show lower repulsion at the interface, accumulating more at the OHP, thus triggering local promoting effects. Water dissociation kinetics is increasingly promoted by strongly acidic cations (Nd3+, Al3+), in agreement with experimental evidence. Cs+, Ba2+, and Nd3+ coordinate to adsorbed CO2 steadily; thus they enable*CO2- stabilization and barrierless protonation to COOH and further reduction products

Chromosome contribution to Andean Polyploid Species of Senecio (Asteraceae), from Argentina

Meiotic chromosome numbers were determined and observations of meiotic behavior were made in six species and two hybrid specimens of Senecio L. (Asteraceae). Two different numbers were found: 2n=4x=40 in S. pogonias Cabr., S. ragonesei Cabr., S. sectilis Griseb. and S. viridis Phil. var. radiatus R. E. Fr. and 2n=8x=80 in S. subulatus D. Don. var. subulatus and in S. uspallatensis Hook. et Arn.; the latter showed the same chromosome number previously reported. The chromosome number of the hybrid individuals was 2n=4x=40, being their putative parents S. ragonesei and S. sectilis. B chromosomes were found in some individuals of S. pogonias, S. sectilis, S. subulatus var. subulatus and S. uspallatensis. Many meiotic irregularities such as bridges, fragments, laggard chromosomes, micronuclei and cellular fusion were observed. The results are analyzed in relation to the persistence and success of these polyploids, and the speciation mechanisms operating within this group are discussed.Facultad de Ciencias Naturales y Muse

Analysis of mitochondrial enzymatic activity in blood lymphomonocyte fractions during infection with different Trypanosoma cruzi strains

Proinflammatory and inflammatory mediators induced by Trypanosoma cruzi infection increase the oxidative stress, generating toxicity for cells targeting mitochondria of different tissues. We studied the activity of citrate synthase and complexes I-IV of respiratory chain in mitochondria of blood lymphomonocyte fraction, from albino Swiss mice infected with different isolates of T. cruzi, during Chagas disease evolution. Complexes I-IV were modified in infected groups (p&lt;0.05) in all the stages, and an inflammatory process of different magnitudes was detected in the heart and skeletal muscle according to the isolate. The citrate synthase activity presented modifications in the SGO Z12 and the Tulahuen group (p&lt;0.05). Hearts showed fiber fragmentation and fibrosis; skeletal muscle presented inflammatory infiltrates and in the Tulahuen infected group, there were also amastigote nests. The inflammatory processes produced an oxidative stress that induced different alterations of mitochondrial enzymes activities in the lymphomonocyte fraction that can be detected by a simple blood extraction, suggesting that they could be used as disease markers, especially in the indeterminate phase of Chagas disease

Environmental differences are correlated with the distribution pattern of cytotypes in Veronica subsection Pentasepalae at a broad scale

[EN] Background and Aims: The distribution of cytotypes and its potential correlation with environmental variables represent a cornerstone to understanding the origin and maintenance of polyploid lineages. Although many studies have addressed this question in single species at a regional scale, only a few have attempted to decipher this enigma in groups of closely related species at a broad intercontinental geographical scale. Here, we consider approx. 20 species of a diploid–polyploid complex (Veronica subsect. Pentasepalae) of recent and rapid diversification represented in Europe and North Africa to study the frequency and distribution of cytotypes and their relationship to environmental variables. Methods: A total of 680 individuals (207 populations) were sampled. Ploidy levels were determined using flow cytometry. Ecological differentiation among cytotypes was tested using climatic and environmental variables related to temperature, precipitation, vegetation and biogeographical region, among others, and by performing univariate and multivariate (constrained principal coordinates analysis) analyses. Key Results: Four ploidy levels (2x, 4x, 6x and 8x) were found and genome downsizing was observed to occur within the group. Plants of different ploidy level are ecologically differentiated, with hexaploids and octoploids occurring in wetter and colder habitats with a higher seasonality than diploids. A south to north distribution pattern was found, with diploids occupying southern refugial areas and octoploids being more frequent in northern regions of Europe above the permafrost boundary. Conclusions: The distribution of cytotypes can be explained by ecological differentiation, the geographical position of refuge areas during the Quaternary climatic oscillations as well as by ice and permafrost retreat patterns. The Balkan Peninsula constitutes the most important contact zone between cytotypes. This work provides the first comprehensive ploidy screening within V. subsect. Pentasepalae at a broad scale and indicates that polyploidy and genome downsizing might have contributed to the colonization of new habitats in a recently diverged polyploid complex.Spanish Ministerio de Economía y Competitividad [projects CGL2009-07555 and CGL2012-32574]; the Spanish Ministerio de Ciencia e Innovación [PhD grants AP2008-03434 to B.R.A. and AP2010-2968 to N.L.G.]; and the University of Salamanca [PhD grant to N.P.G. co-financed by Banco Santander]

In vitro antimicrobial activity of mexican plants on bovine mastitis bacteria: preliminary studies

The present study aimed to evaluate the efficacy of traditionally used antibacterial plants (Euphorbia prostrata, Schinus molle, Brickellia veronicaefolia and Lepidium virginicum) in Santa Rosa Range in Guanajuato against major mastitis-causing pathogens. The selected plants were phytochemically screened for alkaloids, flavonoids, polyphenols, saponins, anthraquinone, cardiac glycosides, steroids and terpenoids. Moreover, to achieve the main purpose of the present research, extracts of selected plants were tested for in vitro antibacterial activity against Staphylococcus aureus, Escherichia coli, Shigella spp., Bacillus subtilis, Clavibacter spp., Proteus vulgaris and Salmonella spp. All these bacterial were isolated from clinical mastitis in dairy cows. The results indicated that the ethanolic extract of the aerial part of L. virginicum exhibited the strongest antimicrobial activity, and it could be potential candidate specie for the development of novel veterinary drugs with low cost and fewer side effects

Perfil microbiológico y sensibilidad a antibióticos de microorganismos aislados de infecciones conjuntivales en el Instituto de Oftalmología Fundación Conde de Valenciana. Reporte del año 2012

ResumenIntroducciónLa conjuntiva es el tejido ocular que se infecta con mayor frecuencia. Los agentes patógenos más frecuentes de la conjuntivitis suelen ser los virus y las bacterias. El uso indiscriminado de antibióticos de amplio espectro para tratar la conjuntivitis ha generado microorganismos resistentes.ObjetivoIdentificar los microorganismos más frecuentes aislados de muestras de origen conjuntival y conocer su susceptibilidad antibiótica.Material y métodosRevisión retrospectiva de cultivos provenientes de raspados conjuntivales obtenidos durante el 2012.ResultadosSe obtuvieron 44 muestras de origen conjuntival. Estas provinieron de 21 varones y 23 mujeres. La mediana (25%, 75%) de la edad fue 62 años (39-68). El cultivo fue positivo en 13 de las muestras obtenidas, identificándose 5 microorganismos diferentes. Staphylococcus epidermidis fue el microorganismo aislado con mayor frecuencia (9 cepas). Todas las cepas de S. epidermidis fueron sensibles a vancomicina, gentamicina, cefotaxima, moxifloxacino y ofloxacino. La mayoría de las cepas de S. epidermidis (6/9) mostraron resistencia a múltiples antibióticos.ConclusionesStaphylococcus epidermidis fue el microorganismo aislado con mayor frecuencia en muestras provenientes de infecciones conjuntivales. Todas las cepas de S. epidermidis fueron sensibles a vancomicina, gentamicina y moxifloxacino y la mayoría de ellas fueron multirresistentes a los antibióticos en evaluación.AbstractIntroductionThe conjunctiva is the tissue of the eye that gets infected with more frequency. The most common pathogens of conjunctivitis are viruses and bacteria. The indiscriminate use of broad-spectrum antibiotics to treat conjunctivitis generated resistant microorganisms.ObjectiveIdentify the most common microorganisms isolated from samples of conjunctival origin and know their antibiotic susceptibility.Material and methodsRetrospective review of culture from conjunctival swabs obtained during 2012.ResultsWe collected 44 samples of conjunctival origin. They came from 21 males and 23 women. The median (25%, 75%) of age was 62 years (39-68). The culture was positive in 13 samples, identifying five different microorganisms. Staphylococcus epidermidis was the most common isolated microorganism (9 strains). All strains of S. epidermidis were sensitive to vancomycin, gentamicin, cefotaxime, ofloxacin and moxifloxacin. The multiple antibiotic resistance was identified in the majority of strains of S. epidermidis (6/9).ConclusionsStaphylococcus epidermidis was the most common isolated microorganism from samples of conjuntival infections. All strains of S. epidermidis were sensitive to vancomycin and moxifloxacin and most of them showed multidrug resistance to antibiotics

Exploring green gentrification in 28 global North cities : the role of urban parks and other types of greenspaces

Unidad de excelencia María de Maeztu CEX2019-000940-MAlthough cities globally are increasingly mobilizing re-naturing projects to address diverse urban socio-environmental and health challenges, there is mounting evidence that these interventions may also be linked to the phenomenon known as green gentrification. However, to date the empirical evidence on the relationship between greenspaces and gentrification regarding associations with different greenspace types remains scarce. This study focused on 28 mid-sized cities in North America and Western Europe. We assessed improved access to different types of greenspace (i.e. total area of parks, gardens, nature preserves, recreational areas or greenways [i] added before the 2000s or [ii] added before the 2010s) and gentrification processes (including [i] gentrification for the 2000s; [ii] gentrification for the 2010s; [iii] gentrification throughout the decades of the 2000s and 2010s) in each small geographical unit of each city. To estimate the associations, we developed a Bayesian hierarchical spatial model foreach city and gentrification time period (i.e. a maximum of three models per city). More than half of our models showed that parks-together with other factors such as proximity to the city center-are positively associated with gentrification processes, particularly in the US context, except in historically Black disinvested postindustrial cities with lots of vacant land. We also find than in half of our models newly designated nature preserves are negatively associated with gentrification processes, particularly when considering gentrification throughout the 2000s and the 2010s and in the US. Meanwhile, for new gardens, recreational spaces and greenways, our research shows mixed results (some positive, some negative and some no effect associations). Considering the environmental and health benefits of urban re-naturing projects, cities should keep investing in improving park access while simultaneously implementing anti-displacement and inclusive green policies

Investigación educativa y narrativas biográficas: la experiencia de formación de maestrandos y egresados en contexto COVID-19 y post COVID-19

El presente trabajo propone una lectura analítica de historias de vida, en clave de narrativas, de experiencias de maestrandos y egresados que incursionan durante el período 2020-2021 en la investigación educativa. Se funda en un enfoque interpretativo con herramientas metodológicas biográfico-narrativas de investigación en ciencias sociales. De este modo, la historia de vida se inscribe tanto como perspectiva socioantropológica de registro de diversa información proporcionada por los sujetos cuanto como género documental, aspecto este desde el cual se ponen de manifiesto sus caracteres discursivos. Los textos ofrecen en primera persona el recorte de un momento vital que -en el marco de la pandemia COVID-19- no solo se hace eco de este suceso de alto valor condicionante de futuras transformaciones, sino que además permite la posibilidad de reflexionar sobre las vivencias, contradicciones, interrogantes y aprendizajes que la experiencia del ingreso al equipo de investigación les permite construir como registro subjetivo

Lack of Galactose or Galacturonic Acid in <i>Bradyrhizobium japonicum</i> USDA 110 Exopolysaccharide Leads to Different Symbiotic Responses in Soybean

Exopolysaccharide (EPS) and lipopolysaccharide (LPS) from Bradyrhizobium japonicum are important for infection and nodulation of soybean (Glycine max), although their roles are not completely understood. To better understand this, we constructed mutants in B. japonicum USDA 110 impaired in galactose or galacturonic acid incorporation into the EPS without affecting the LPS. The derivative LP 3010 had a deletion of lspL-ugdH and produced EPS without galacturonic acid whereas LP 3013, with an insertion in exoB, produced EPS without galactose. In addition, the strain LP 3017, with both mutations, had EPS devoid of both galactosides. The missing galactosides were not replaced by other sugars. The defects in EPS had different consequences. LP 3010 formed biofilms and nodulated but was defective in competitiveness for nodulation; and, inside nodules, the peribacteroid membranes tended to fuse, leading to the merging of symbiosomes. Meanwhile, LP 3013 and LP 3017 were unable to form biofilms and produced empty pseudonodules but exoB suppressor mutants were obtained when LP 3013 plant inoculation was supplemented with wild-type EPS. Similar phenotypes were observed with all these mutants in G. soja. Therefore, the lack of each galactoside in the EPS has a different functional effect on the B. japonicum-soybean symbiosis.Facultad de Ciencias ExactasInstituto de Biotecnologia y Biologia Molecula

Crossing the Interspecies Barrier: Opening the Door to Zoonotic Pathogens

The number of pathogens known to infect humans is ever increasing. Whether such increase reflects improved surveillance and detection or actual emergence of novel pathogens is unclear. Nonetheless, infectious diseases are the second leading cause of human mortality and disability-adjusted life years lost worldwide [1], [2]. On average, three to four new pathogen species are detected in the human population every year [3]. Most of these emerging pathogens originate from nonhuman animal species