Efficient CO2 electroreduction on tin modified cuprous oxide synthesized via a one-pot microwave-assisted route

Bimetallic copper-tin catalysts are considered cost-effective and suitable for large-scale electrochemical conversion of CO2 to valuable products. In this work, a class of tin (Sn) modified cuprous oxide (Cu2O) is simply synthesized through a one-pot microwave-assisted solvothermal method and thoroughly characterized by various techniques. Sn is uniformly distributed on the Cu2O crystals showing a cube-within-cube structure, and CuSn alloy phase emerges at high Sn contents. The atomic ratio of Cu to Sn is found to be crucially important for the selectivity of the CO2 reduction reaction, and a ratio of 11.6 leads to the optimal selectivity for CO. This electrode shows a high current density of 47.2 mA cm−2 for CO formation at −1.0 V vs. the reversible hydrogen electrode and also displays good CO selectivity of 80–90% in a wide potential range. In particular, considerable CO selectivity of 72–81% is achieved at relatively low overpotentials from 240 mV to 340 mV. During the long-term tests, satisfactory stability is observed for the optimal electrode in terms of both electrode activity and CO selectivity. The relatively low price, the fast and scalable synthesis, and the encouraging performance of the proposed material implies its good potential to be implemented in large-scale CO2 electrolyzers

Biochar/Zinc Oxide Composites as Effective Catalysts for Electrochemical CO2 Reduction

Novel electrocatalysts based on zinc oxide (ZnO) and biochars are prepared through a simple and scalable route and are proposed for the electrocatalytic reduction of CO2 (CO2RR). Materials with different weight ratios of ZnO to biochars, namely, pyrolyzed chitosan (CTO) and pyrolyzed brewed waste coffee (CBC), are synthesized and thoroughly characterized. The physicochemical properties of the materials are correlated with the CO2RR to CO performance in a comprehensive study. Both the type and weight percentage of biochar significantly influence the catalytic performance of the composite. CTO, which has pyridinic- and pyridone-N species in its structure, outperforms CBC as a carbon matrix for ZnO particles, as evidenced by a higher CO selectivity and an enhanced current density at the ZnO_CTO electrode under the same conditions. The study on various ZnO to CTO weight ratios shows that the composite with 40.6 wt % of biochar shows the best performance, with the CO selectivity peaked at 85.8% at -1.1 V versus the reversible hydrogen electrode (RHE) and a CO partial current density of 75.6 mA cm-2 at -1.3 V versus RHE. It also demonstrates good stability during the long-term CO2 electrolysis, showing high retention in both CO selectivity and electrode activity

Facile synthesis of cubic cuprous oxide for electrochemical reduction of carbon dioxide

Abstract: High level of atmospheric carbon dioxide (CO2) concentration is considered one of the main causes of global warming. Electrochemical conversion of CO2 into valuable chemicals and fuels has promising potential to be implemented into practical and sustainable devices. In order to efficiently realize this strategy, one of the biggest efforts has been focused on the design of catalysts which are inexpensive, active and selective and can be produced through green and up-scalable routes. In this work, copper-based materials are simply synthesized via microwave-assisted process and carefully characterized by physical/chemical/electrochemical techniques. Nanoparticle with a cupric oxide (CuO) surface as well as various cuprous oxide (Cu2O) cubes with different sizes is obtained and used for the CO2 reduction reaction. It is observed that the Cu2O-derived electrodes show enhanced activity and carbon monoxide (CO) selectivity compared to the CuO-derived one. Among various Cu2O catalysts, the one with the smallest cubes leads to the best CO selectivity of the electrode, attributed to a higher electrochemically active surface area. Under applied potentials, all Cu2O cubes undergo structural and morphological modification, even though the cubic shape is retained. The nanoclusters formed during the material evolution offer abundant and active reaction sites, leading to the high performance of the Cu2O-derived electrodes

Enfermedad de Creutzfeld Jakob, desafío diagnóstico : reporte de dos casos en la ciudad de Mendoza

La enfermedad de Creutzfeldt-Jakob (ECJ) es una afección neurodege-nerativa rápidamente progresiva y mortal producida por priones. Es la más común de las encefalopatías espongiformes. La hipótesis prevalente sugiere que se inicia y propaga por conversión de una proteína priónica normal (PrP) en una isoforma conformacional anormal (PrPreS), que se acumula en el cerebro causando destrucción neuronal. Se reporta el caso de dos pacientes asistido en el Servicio de Neurología del Hospital Lagomaggiore de la ciudad de Mendoza en el período de 2 años: mujer de 49 años con cuadro de deterioro cognitivo rápidamente progresivo asociado a trastorno de la marcha y ataxia de 2 meses de evolución; y varón de 54 años con conductas inapropiadas y desorientación temporo-espacial de 20 días de evolución. Ambos con EEG compatible y proteína 14.3.3 positiva, falleciendo semanas después del diagnóstico. Se discute ambos casos, los cuales representaron un desafío diagnóstico dada la baja frecuencia y escaso reconocimiento de esta entidad en nuestro medio, debiendo debe ser considerado en pacientes que evolucionan a una demencia rápidamente progresiva.Creutzfeldt-Jakob disease (CJD) is a rapidly progressive and fatal neurodegenerative disease caused by prions. It is the most common of spongiform encephalopathies. The most accepted hypothesis suggests that it initiates and propagates through conversion of normal prion protein (PrP) in an abnormal conformational isoform (PrPres), which accumulates in the brain causing neuronal destruction. The cases of two patients assisted in the Department of Neurology of Hospital Lagomaggiore city of Mendoza in 2-year period are reported: A 49-year old female patient with symptoms of rapidly progressing cognitive impairment associated with gait disturbance and ataxia of 2 months of progression; and a 54-year old male with misconduct and temporo-spatial disorientation of 20 days of evolution. In both cases, EEG was compatible with CJD and 14.3.3 protein was positive, dying weeks after diagnosis. Both cases are discussed, which represented a diagnostic challenge given the low frequency and little recognition of this entity in our environment, must be considered in patients who develop a rapidly progressive dementia.Fil: Galiana, Graciana Lourdes. Hospital Luis Lagomaggiore (Mendoza, Argentina)Fil: Farfan Alé, F.. Hospital Luis Lagomaggiore (Mendoza, Argentina)Fil: De Monte, M.. Hospital Luis Lagomaggiore (Mendoza, Argentina)Fil: Sánchez, C.. Hospital Luis Lagomaggiore (Mendoza, Argentina)Fil: Torres, A.. Hospital Luis Lagomaggiore (Mendoza, Argentina)Fil: Ianardi, S.. Hospital Luis Lagomaggiore (Mendoza, Argentina)Fil: Genco, J.. Hospital Luis Lagomaggiore (Mendoza, Argentina)Fil: Genco, D.. Hospital Luis Lagomaggiore (Mendoza, Argentina)Fil: Castellino, G.. Hospital Luis Lagomaggiore (Mendoza, Argentina

Conformational Changes in Conantokin-G Induced upon Binding of Calcium and Magnesium as Revealed by NMR Structural Analysis

The apo- and metal-bound solution conformations of synthetic conantokin-G (con-G, G1Egamma gammaL5Q gamma NQgamma 10LIRgamma K15SN-CONH2, gamma = gamma-carboxyglutamic acid), an antagonist of N-methyl-D-aspartate receptor-derived neuronal ion channels, have been examined by one- and two-dimensional 1H NMR at neutral pH. A complete structure for the Mg2+-loaded peptide was defined by use of distance geometry calculations and was found to exist as an alpha-helix that spans the entire peptide. The alpha-helical nature of Mg2+/con-G was also supported by the small values (<5.5 Hz) of the 3JHNalpha coupling constants measured for amino acid residues 3-5, 8, 9, and 11-16, and the small values (<4 ppb/K) of the temperature coefficients observed for the alphaNH protons of residues 5-17. This conformation contrasted with that obtained for apo-con-G, which was nearly structureless in solution. Docking of Mg2+ into con-G was accomplished by use of the genetic algorithm/molecular dynamics simulation method, employing the NMR-derived Mg2+-loaded structure for initial coordinates in the midpoint calculations. For the 3 Mg2+/con-G model, it was found that binding of one Mg2+ ion is stabilized by oxygen atoms from three gamma-carboxylates of Gla3, Gla4, and Gla7; another Mg2+ is coordinated by two oxygen atoms, one from each of the gamma-carboxylates of Gla7; and a third metal ion through three donor oxygen atoms of gamma-carboxylates from Gla10 and Gla14. As shown from direct metal binding measurements to mutant con-G peptides, these latter two Gla residues probably stabilized the tightest binding Mg2+ ion. Circular dichroism studies of these same peptide variants demonstrated that all Gla residues contribute to the adoption of the Mg2+-dependent alpha-helical conformation in con-G. The data obtained in this investigation provide a molecular basis for the large conformational alteration observed in apo-con-G as a result of divalent cation binding and allow assessment of the roles of individual Gla residues in defining certain of the structure-function properties of con-G

Heterozygosity for Pten Promotes Tumorigenesis in a Mouse Model of Medulloblastoma

BACKGROUND: Recent publications have described an important role for cross talk between PI-3 kinase and sonic hedgehog signaling pathways in the pathogenesis of medulloblastoma. METHODOLOGY/PRINCIPAL FINDINGS: We crossed mice with constitutive activation of Smoothened, SmoA1, with Pten deficient mice. Both constitutive and conditional Pten deficiency doubled the incidence of mice with symptoms of medulloblastoma and resulted in decreased survival. Analysis revealed a clear separation of gene signatures, with up-regulation of genes in the PI-3 kinase signaling pathway, including downstream activation of angiogenesis in SmoA1+/-; Pten +/- medulloblastomas. Western blotting and immunohistochemistry confirmed reduced or absent Pten, Akt activation, and increased angiogenesis in Pten deficient tumors. Down-regulated genes included genes in the sonic hedgehog pathway and tumor suppressor genes. SmoA1+/-; Pten +/+ medulloblastomas appeared classic in histology with increased proliferation and diffuse staining for apoptosis. In contrast, Pten deficient tumors exhibited extensive nodularity with neuronal differentiation separated by focal areas of intense staining for proliferation and virtually absent apoptosis. Examination of human medulloblastomas revealed low to absent PTEN expression in over half of the tumors. Kaplan-Meier analysis confirmed worse overall survival in patients whose tumor exhibited low to absent PTEN expression. CONCLUSIONS/SIGNIFICANCE: This suggests that PTEN expression is a marker of favorable prognosis and mouse models with activation of PI-3 kinase pathways may be important tools for preclinical evaluation of promising agents for the treatment of medulloblastoma

Contributions of thrombin targets to tissue factor-dependent metastasis in hyperthrombotic mice

Tumor cell tissue factor (TF)-initiated coagulation supports hematogenous metastasis by fibrin formation, platelet activation, and monocyte/macrophage recruitment. Recent studies identified host anticoagulant mechanisms as a major impediment for successful hematogenous tumor cell metastasis

Joint management of shared resources as an alternative approach for addressing maritime boundary disputes : the Kenya-Somalia maritime boundary dispute

Socio-economic security has motivated African states to explore natural resources in areas of overlapping maritime claims. However, Africa’s maritime boundaries are characterized by unresolved disputes. Resolution of these disputes is time-consuming, expensive and can undermine the state’s ability to exploit natural resources. The Somalia and Kenya maritime dispute under litigation with the International Court of Justice demonstrates the continental commitment to peaceful resolution. Citing cases from across Africa, we discuss outright delimitation or Joint Management Zones (JMZs) as means to address disputes over shared resources, particularly transboundary fisheries, which have received little attention. Reframing the Kenya-Somalia maritime dispute resolution process as cooperation over fisheries management will have spill-over effects into greater diplomatic relations. Fish do not abide by maritime boundaries. As such, we posit that the peaceful resolution of maritime boundary disputes lies in Africa’s ability to consider settlements by way of JMZs to motivate sustainable use of natural resources.PostprintPeer reviewe