How palladium inhibits CO poisoning during electrocatalytic formic acid oxidation and carbon dioxide reduction.

Development of reversible and stable catalysts for the electrochemical reduction of CO2 is of great interest. Here, we elucidate the atomistic details of how a palladium electrocatalyst inhibits CO poisoning during both formic acid oxidation to carbon dioxide and carbon dioxide reduction to formic acid. We compare results obtained with a platinum single-crystal electrode modified with and without a single monolayer of palladium. We combine (high-scan-rate) cyclic voltammetry with density functional theory to explain the absence of CO poisoning on the palladium-modified electrode. We show how the high formate coverage on the palladium-modified electrode protects the surface from poisoning during formic acid oxidation, and how the adsorption of CO precursor dictates the delayed poisoning during CO2 reduction. The nature of the hydrogen adsorbed on the palladium-modified electrode is considerably different from platinum, supporting a model to explain the reversibility of this reaction. Our results help in designing catalysts for which CO poisoning needs to be avoided.

A simple method to calculate solution-phase free energies of charged species in computational electrocatalysis.

Determining the adsorption potential of adsorbed ions in the field of computational electrocatalysis is of great interest to study their interaction with the electrode material and the solvent, and to map out surface phase diagrams and reaction pathways. Calculating the adsorption potentials of ions with density functional theory and comparing across various ions requires an accurate reference energy of the ion in solution and electrons at the same electrochemical scale. Here we highlight a previously used method for determining the reference free energy of solution phase ions using a simple electrochemical thermodynamic cycle, which allows this free energy to be calculated from that of a neutral gas-phase or solid species and an experimentally measured equilibrium potential, avoiding the need to model solvent around the solution phase ion in the electronic structure calculations. While this method is not new, we describe its use and utility in detail and show that this same method can be used to find the free energy of any ion from any reaction, as long as the half-cell equilibrium potential is known, even for reactions that do not transfer the same number of protons and electrons. To illustrate its usability, we compare the adsorption potentials obtained with DFT of I*, Br*, Cl*, and SO4*on Pt(111) and Au(111) and OH*and Ag*on Pt(111) with those measured experimentally and find that this simple and computationally affordable method reproduces the experimental trends.

Psychosocial rehabilitation experiences of women victims of armed conflict in Montes de María, Colombia.

BACKGROUND: After 9 years of the ground-breaking social policy Law 1448 of 2011 -Victims Law- and its extension until 2030, the Colombian State and other stakeholders have made several efforts towards granting the right of integral reparation for more than 9 million victims that are recognized in the Colombian transitional context. Psychosocial rehabilitation is a Victims Law's reparation measure whose objective is to re-establish the psychosocial, physical and mental health welfare in the individual, familiar and community levels. This study aims to understand the experiences of psychosocial rehabilitation of women victims of armed conflict in Montes de Maria and the underlying social intervention paradigms that guide the Law's implementation. METHODS: Based on a qualitative design with a phenomenological approach, narrative tools and thematic network analysis permitted to give voice to the women participants. Individual narrative interviews were conducted with 12 women victims and a focus group with eight of them was used as a triangulation strategy. RESULTS: Although the Victims Law is oriented by a sociopolitical intervention paradigm, the stories of the women's victims of Montes de María mainly evidenced non-sociopolitical interventions with humanitarian assistance towards revictimization and State abandonment. As a coping mechanism towards the State negligence encountered, women strive to overcome psychosocial trauma by developing agency and community resources for the resignification of the traumatic experiences and peacebuilding. CONCLUSIONS: For the Victims Law to achieve its integrality aim, the psychosocial approach should be implemented through all its measures but remains absent in Montes de Maria. The diversity of victim's individual and collective initiatives that were found, can contribute towards transformative and participatory psychosocial intervention with community's resources. Women victims can perform as advisors and collaborators in the implementation of individual and collective reparation, which remains as an opportunity for psychosocial rehabilitation and peacebuilding. Further monitoring and evaluation of the law with a territorial and differential perspective is required to respond to the victim's needs.

Adsorption processes on a Pd monolayer-modified Pt(111) electrode.

Specific adsorption of anions is an important aspect in surface electrochemistry for its influence on reaction kinetics in either a promoted or inhibited fashion. Perchloric acid is typically considered as an ideal electrolyte for investigating electrocatalytic reactions due to the lack of specific adsorption of the perchlorate anion on several metal electrodes. In this work, cyclic voltammetry and computational methods are combined to investigate the interfacial processes on a Pd monolayer deposited on Pt(111) single crystal electrode in perchloric acid solution. The "hydrogen region" of this PdMLPt(111) surface exhibits two voltammetric peaks: the first "hydrogen peak" at 0.246 VRHE actually involves the replacement of hydrogen by hydroxyl, and the second "hydrogen peak" HII at 0.306 VRHE appears to be the replacement of adsorbed hydroxyl by specific perchlorate adsorption. The two peaks merge into a single peak when a more strongly adsorbed anion, such as sulfate, is involved. Our density functional theory calculations qualitatively support the peak assignment and show that anions generally bind more strongly to the PdMLPt(111) surface than to Pt(111).

Influence of Van der Waals Interactions on the Solvation Energies of Adsorbates at Pt-Based Electrocatalysts.

Solvation can significantly modify the adsorption energy of species at surfaces, thereby influencing the performance of electrocatalysts and liquid-phase catalysts. Thus, it is important to understand adsorbate solvation at the nanoscale. Here we evaluate the effect of van der Waals (vdW) interactions described by different approaches on the solvation energy of *OH adsorbed on near-surface alloys (NSAs) of Pt. Our results show that the studied functionals can be divided into two groups, each with rather similar average *OH solvation energies: (1) PBE and PW91; and (2) vdW functionals, RPBE, PBE-D3 and RPBE-D3. On average, *OH solvation energies are less negative by ∼0.14 eV in group (2) compared to (1), and the values for a given alloy can be extrapolated from one functional to another within the same group. Depending on the desired level of accuracy, these concrete observations and our tabulated values can be used to rapidly incorporate solvation into models for electrocatalysis and liquid-phase catalysis.

Bimetallic dimers adsorbed on a defect-free MgO(001) surface: bonding, structure and reactivity.

A large number of computational studies have been devoted to the investigation of monometallic clusters supported by MgO. However, in practice, catalysis shows that multicomponent catalytic systems often win in catalytic performance over single component systems. In this study, the geometrical and electronic structure, stability and chemisorption properties of M1M2 metal dimers (M1, M2 = Ru, Rh, Pd, Ir, Pt) supported by defect free MgO(001) have been investigated in the framework of density functional theory. The oxygen sites of MgO(001) are the preferred adsorption sites for all the studied clusters, the majority of them adsorbing parallel to the surface with metal atoms attached to two surface oxygen atoms. The energetics of M1M2 + MgO(001) formation shows that the adsorption complexes are stable and benefit from metal-oxygen and metal-metal interaction. The chemisorption properties of Pd and Pt atoms in PdM2 and PtM2 dimers are studied using CO as a probe molecule. A linear relationship between the CO chemisorption and the d-band center position of the reacting atom in the dimer is observed, extending the d-band center model to the case of highly under-coordinated metal atoms supported by a non-conductive material.

Asma: manejo intra-hospitalario, evaluación de las crisis y tratamiento en el Hospital Militar San Cristobal: enero 93 a junio 95 / Asthma: management intra-hospitalary, evaluation of the crisis and treatment in the Hospital Militar San Cristobal: january 93 a june 95

Se estudiaron 50 pacientes hospitalizados en lapso de tiempo comprendido entre enero 93-junio 95 en el Hospital de San Cristobal, en los cuales se obtuvo resultados esperados de acuerdo a la casuística utilizada, en el cual resalta el sexo masculino, factores ambientales, crisis asmática, como criterio de hospitalización

Neumonías: diagnóstico-evaluación y tratamiento en el Hospimil San Cristobal: enero 1993-junio 1995 / Pneumonia: diagnosis-evaluation and treatment in the Hospimil San Cristobal: january 1993-june 1995

Las infecciones del tracto respitarorio son aún una causa importante de morbilidad y mortalidad; la selección de un tratamiento antibiótico específico de la neumonía, depende de la identificación del patógeno causante o del juicio sobre el mismo. En este estudio retrospectivo se analizaron 80 pacientes hospitalizados en el Hospimil San Cristobal, su evolución y seguimiento intrahospitalario. Para definir criterios y conductas a seguir en el manejo más adecuado con neumonías en nuestro Hospimil