The role of a slow phase formation process in the growth of anodic silver oxide layers in alkaline solutions—I. Electroformation of Ag(I) oxide layer

The anodic electroformation of silver (I) oxide layer on polycrystalline silver electrodes in 0.1 M NaOH was studied by using potentiodynamic and potentiostatic techniques. The growth of the silver oxide layer under a linear potential sweep or potential step measurements involves as a first step the electroformation of Ag2O or AgOH monolayer at potentials close to the Ag/Ag2O reversible electrode potential. This monolayer grows through a solid diffusion mechanism to form a 3-D primary silver (I) oxide. Subsequently the building up of a secondary silver (I) oxide layer is clearly noticed when the potential exceeds 0.24 V (vs sce). The formation of this layer can be described in terms of an instantaneous nucleation and 3-D growth mechanism under diffusion control. The ageing effects at the primary layer level decreases the nucleation rate so that for the growth of the secondary layer an intermediate situation between instantaneous and progressive nucleation under diffusion control can be observed. The secondary silver (I) oxide layer can be related to the aged silver (I) oxide species previously reported.Instituto de Investigaciones Fisicoquímicas Teóricas y AplicadasFacultad de Ciencias Exacta

The role of a slow phase formation process in the growth of anodic silver oxide layers in alkaline solutions—I. Electroformation of Ag(I) oxide layer

The anodic electroformation of silver (I) oxide layer on polycrystalline silver electrodes in 0.1 M NaOH was studied by using potentiodynamic and potentiostatic techniques. The growth of the silver oxide layer under a linear potential sweep or potential step measurements involves as a first step the electroformation of Ag2O or AgOH monolayer at potentials close to the Ag/Ag2O reversible electrode potential. This monolayer grows through a solid diffusion mechanism to form a 3-D primary silver (I) oxide. Subsequently the building up of a secondary silver (I) oxide layer is clearly noticed when the potential exceeds 0.24 V (vs sce). The formation of this layer can be described in terms of an instantaneous nucleation and 3-D growth mechanism under diffusion control. The ageing effects at the primary layer level decreases the nucleation rate so that for the growth of the secondary layer an intermediate situation between instantaneous and progressive nucleation under diffusion control can be observed. The secondary silver (I) oxide layer can be related to the aged silver (I) oxide species previously reported.Instituto de Investigaciones Fisicoquímicas Teóricas y AplicadasFacultad de Ciencias Exacta

Experiencias en la relación disciplinar de la matemática en la carrera de meteorología

Se presenta el método de concebir el proyecto interdisciplinario integrado en la carrera de Meteorología, que tiene como eje rector la interdisciplinariedad y como metodología la formación académica por competencias. Identificadas éstas en cada semestre se ilustra el diseño de Cálculo y Geometría I y II en su contribución al desempeño cognitivo: comprensión, análisis, interpretación y representación y modelación/simulación. Se muestra el sistema de tareas docentes integradas fundamentalmente a la Disciplina Física y a la Disciplina Integradora. Se analizan los resultados: armónica integración de las acciones didácticas entre profesores y una mejor orientación a los alumnos

Kinetic study of silver (I) oxide layer electroreduction

The potentiostatic electroreduction of silver(I) oxide layer has been investigated in 0.1 M NaOH. The study was complemented by electroreduced silver surface characterisation through scanning electron microscopy micrographs and thallium UPD voltammetry. By properly adjusting the electroreduction conditions three well-defined processes could be distinguished: (i) the electroreduction of the Ag2O monolayer in direct contact with the silver substrate which involves a current decay following a first order law; (ii) the electroreduction of the primary Ag2O layer which can be described through an instantaneous nucleation and 3-D growth mechanism under diffusion control; (iii) the electroreduction of the secondary Ag2O layer involving a nucleation and 3-D conical growth under charge transfer control and a correction term for the death of growing nuclei. SEM and thallium UPD results correlate, in principle, with the conclusions derived from the electrochemical data.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

The role of a slow phase formation process in the growth of anodic silver oxide layers in alkaline solutions—I. Electroformation of Ag(I) oxide layer

The anodic electroformation of silver (I) oxide layer on polycrystalline silver electrodes in 0.1 M NaOH was studied by using potentiodynamic and potentiostatic techniques. The growth of the silver oxide layer under a linear potential sweep or potential step measurements involves as a first step the electroformation of Ag2O or AgOH monolayer at potentials close to the Ag/Ag2O reversible electrode potential. This monolayer grows through a solid diffusion mechanism to form a 3-D primary silver (I) oxide. Subsequently the building up of a secondary silver (I) oxide layer is clearly noticed when the potential exceeds 0.24 V (vs sce). The formation of this layer can be described in terms of an instantaneous nucleation and 3-D growth mechanism under diffusion control. The ageing effects at the primary layer level decreases the nucleation rate so that for the growth of the secondary layer an intermediate situation between instantaneous and progressive nucleation under diffusion control can be observed. The secondary silver (I) oxide layer can be related to the aged silver (I) oxide species previously reported.Instituto de Investigaciones Fisicoquímicas Teóricas y AplicadasFacultad de Ciencias Exacta

Kinetics and mechanism of the silver (I) oxide to silver (II) oxide layer electrooxidation reaction

The electroformation of Ag(II) oxide layer during the anodization of silver in 0.1 M NaOH is investigated under potentiostatic and potentiodynamic conditions. Results are discussed in terms of nucleation and growth models and statistical analysis of induction times related to the nucleation kinetics of Ag(II) oxide crystals. The best fitting of results comes out from the application of a progressive nucleation and 3-D growth model under mass transfer control where diffusion of species from the electrode to growing sites is essential for further expansion.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Epidemiologic surveillance of nosocomial infections in a Pediatric Intensive Care Unit of a developing country

<p>Abstract</p> <p>Background</p> <p>Nosocomial Infections (NI) are a frequent and relevant problem. The purpose of this study was to determine the epidemiology of the three most common NI in a Pediatric Intensive Care Unit from a developing country.</p> <p>Methods</p> <p>We performed a prospective study in a single Pediatric Intensive Care Unit during 12 months. Children were assessed for 3 NI: bloodstream infections (BSI), ventilator-associated pneumonia (VAP) and urinary tract infections (UTI), according to Center for Disease Control criteria. Use of devices (endotracheal tube [ETT], central venous catheter [CVC] and urinary catheter [UC]) was recorded.</p> <p>Results</p> <p>Four hundred fourteen patients were admitted; 81 patients (19.5%) developed 85 NIs. Density of incidence of BSI, VAP and UTI was 18.1, 7.9 and 5.1/1000 days of use of CVC, ETT and UC respectively. BSI was more common in children with CVCs than in those without CVCs (20% <it>vs</it>. 4.7%, p < 0.05). <it>Candida </it>spp. was the commonest microorganism in BSI (41%), followed by Coagulase-negative <it>Staphylococcus </it>(17%). <it>Pseudomonas </it>(52%) was the most common germ for VAP and <it>Candida </it>(71%) for UTI. The presence of NI was associated with increased mortality (38.2% <it>vs</it>. 20.4% in children without NI; p < 0.001) and the median length of ICU stay (23 <it>vs</it>. 6 days in children without NI; p < 0.001). Children with NI had longer average hospital stay previous to diagnosis of this condition (12.3 <it>vs</it>. 6 days; p < 0.001).</p> <p>Conclusions</p> <p>One of every 5 children acquires an NI in the PICU. Its presence was associated with increased mortality and length of stay. At the same time a longer stay was associated with an increased risk of developing NI.</p

Enabling dynamic and intelligent workflows for HPC, data analytics, and AI convergence

The evolution of High-Performance Computing (HPC) platforms enables the design and execution of progressively larger and more complex workflow applications in these systems. The complexity comes not only from the number of elements that compose the workflows but also from the type of computations they perform. While traditional HPC workflows target simulations and modelling of physical phenomena, current needs require in addition data analytics (DA) and artificial intelligence (AI) tasks. However, the development of these workflows is hampered by the lack of proper programming models and environments that support the integration of HPC, DA, and AI, as well as the lack of tools to easily deploy and execute the workflows in HPC systems. To progress in this direction, this paper presents use cases where complex workflows are required and investigates the main issues to be addressed for the HPC/DA/AI convergence. Based on this study, the paper identifies the challenges of a new workflow platform to manage complex workflows. Finally, it proposes a development approach for such a workflow platform addressing these challenges in two directions: first, by defining a software stack that provides the functionalities to manage these complex workflows; and second, by proposing the HPC Workflow as a Service (HPCWaaS) paradigm, which leverages the software stack to facilitate the reusability of complex workflows in federated HPC infrastructures. Proposals presented in this work are subject to study and development as part of the EuroHPC eFlows4HPC project.This work has received funding from the European High-Performance Computing Joint Undertaking (JU) under grant agreement No 955558. The JU receives support from the European Union’s Horizon 2020 research and innovation programme and Spain, Germany, France, Italy, Poland, Switzerland and Norway. In Spain, it has received complementary funding from MCIN/AEI/10.13039/501100011033, Spain and the European Union NextGenerationEU/PRTR (contracts PCI2021-121957, PCI2021-121931, PCI2021-121944, and PCI2021-121927). In Germany, it has received complementary funding from the German Federal Ministry of Education and Research (contracts 16HPC016K, 6GPC016K, 16HPC017 and 16HPC018). In France, it has received financial support from Caisse des dépôts et consignations (CDC) under the action PIA ADEIP (project Calculateurs). In Italy, it has been preliminary approved for complimentary funding by Ministero dello Sviluppo Economico (MiSE) (ref. project prop. 2659). In Norway, it has received complementary funding from the Norwegian Research Council, Norway under project number 323825. In Switzerland, it has been preliminary approved for complimentary funding by the State Secretariat for Education, Research, and Innovation (SERI), Norway. In Poland, it is partially supported by the National Centre for Research and Development under decision DWM/EuroHPCJU/4/2021. The authors also acknowledge financial support by MCIN/AEI /10.13039/501100011033, Spain through the “Severo Ochoa Programme for Centres of Excellence in R&D” under Grant CEX2018-000797-S, the Spanish Government, Spain (contract PID2019-107255 GB) and by Generalitat de Catalunya, Spain (contract 2017-SGR-01414). Anna Queralt is a Serra Húnter Fellow.With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2018-000797-S)

Clinical-epidemiologic variation in patients treated in the first and second wave of COVID-19 in Lambayeque, Peru: A cluster analysis

"Objectives: To identify differences in the clinical and epidemiologic characteristics of patients during the first and second waves of the COVID-19 pandemic at the EsSalud Lambayeque health care network, Peru. Methods: An analytical cross-sectional study of 53,912 patients enrolled during the first and second waves of COVID-19 was conducted. Cluster analysis based on clustering large applications (CLARA) was applied to clinical-epidemiologic data presented at the time of care. The two pandemic waves were compared using clinical-epidemiologic data from epidemiologic surveillance. Results: Cluster analysis identified four COVID-19 groups with a characteristic pattern. Cluster 1 included the largest number of participants in both waves, and the participants were predominantly female. Cluster 2 included patients with gastrointestinal, respiratory, and systemic symptoms. Cluster 3 was the “severe” cluster, characterized by older adults and patients with dyspnea or comorbidities (cardiovascular, diabetes, obesity). Cluster 4 included asymptomatic, pregnant, and less severe patients. We found differences in all clinical-epidemiologic characteristics according to the cluster to which they belonged. Conclusion: Using cluster analysis, we identified characteristic patterns in each group. Respiratory, gastrointestinal, dyspnea, anosmia, and ageusia symptoms were higher in the second COVID-19 wave than the first COVID-19 wave

Caso probable de fiebre manchada (Rickettsia felis) transmitida por pulgas

Rickettsia felis is the etiologic agent of flea-borne spotted fever, with Ctenocephalides felis as its main vector and reservoir. Typically, the disease presents as acute fever associated with headache, asthenia, generalized maculo-papular rash, and in some cases, an inoculation eschar. In recent years, R. felis has acquired an important role in the etiology of the acute febrile syndrome; it is indeed an emerging infectious disease, albeit underdiagnosed. Indirect immunofluorescence assay (IFA) is currently the reference diagnostic method. However, this technique has limitations related to the cross reactivity among different species of rickettsiae. Herein, we describe a case of a 16 year-old patient with an acute febrile syndrome secondary to probable infection with R. felis. doi: http://dx.doi.org/10.7705/biomedica.v33i0.723Rickettsia felis es el agente etiológico de la fiebre manchada transmitida por pulgas, cuyo principal vector y reservorio es Ctenocephalides felis. Típicamente, la enfermedad se presenta como fiebre aguda asociada a cefalea, astenia, exantema máculo-papular generalizado y, en algunos casos, conescara de inoculación. En los últimos años, R. felis ha venido adquiriendo un papel importante en la etiología del síndrome febril agudo, calificándola como una enfermedad emergente y subdiagnosticada. La inmunofluorescencia indirecta es actualmente el método diagnóstico de referencia. Sin embargo, esta técnica presenta limitaciones relacionadas con la reacción cruzada que existe entre las diferentesespecies del género Rickettsia. En el presente reporte se describe el caso de un paciente de 16 años con síndrome febril agudo secundario a infección probable por R. felis. doi: http://dx.doi.org/10.7705/biomedica.v33i0.723