Ionic mass transfer at horizontals disc electrodes under longitudinal vibration

A dimensionless correlation for ionic mass transfer at horizontal discelectrodes under longitudinal vibration has been obtained. Within a certain range of amplitude and frequency the flow is confined to a cylinder adjacent to the electrode. The fluid boundary layer thickness is rapidly reduced when either the frequency or the amplitude is increased. The longitudinal vibration, under controlled potential conditions, produces an ac component in the total current. A comparison of the mass transfer rate equation with others corresponding to different flow regimes reveals that a critical flow rate exists, above which vibration is more efficient than conventional agitation in increasing the mass transfer rate.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

An experimental study of ionic mass transfer at horizontal ring-disc electrode under longitudinal vibration

The present paper reports a new ring-disc electrode device resulting from a previous study of ionic mass transfer at horizontal disc electrodes under longitudinal vibration. The efficiency of the platinum ring-disc electrode device is established in comparison to that of the rotating ring-disc electrode in a conventional electrochemical system.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Uso sustentable de pastizales naturales como fuente de bioenergía

Uso sustentable de pastizales naturales como fuente de bioenergíaFil: Feldman, Susana. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias; Argentin

Banco de dados de genótipos para melhoramento genético animal.

Neste trabalho, propomos um de banco de dados e sistemas associados para armazenar genótipos baseado no Sistema de Gerenciamento de Banco de Dados (SGBD) PostgreSQL, linguagem de programação C ,Python e a ferramenta Django para o desenvolvimento da interface.CIIC 2014. Nº 14603

Competencias digitales de estudiantes de la maestría en Cuidados Paliativos y Manejo del Dolor

Objective: To determine the digital skills among students of the master’s program in Palliative Care and Pain Management at Universidad Nacional Mayor de San Marcos School of Medicine in 2022.Materials and methods: A non-experimental, descriptive and cross-sectional research. The study population was comprised of students of the master’s program in Palliative Care and Pain Management enrolled in the year 2022. A non-probability sample was used. Data were collected through the survey “Digital Skills in Higher Education Questionnaire” (CDES), consisting of 46 indicators distributed in five factors with a reliability of 0.96 according to Cronbach’s alpha. Data confidentiality and participants’ autonomy were respected.Results: The final sample was made up of 59 students, the average age was 38.03 years and 76.3 % were women. All students had a personal computer and Internet access. The descriptive analysis showed that the “very important” rating prevailed: 49.2 % for the “digital citizenship” factor, 47.5 % for the “communication and collaboration” factor, 45.8 % for the “creativity and innovation” and the “access and use of information” factors, and 44.1 % for the “digital literacy” factor. According to the digital skills global analysis, 49.2 % and 42.4 % chose the “very important” and “important” ratings, respectively. There were no results for the “not at all important” rating. Conclusions: All students had a personal computer and Internet access, which confirms the growing interest in including aspects related to digital skills in university education. The “digital literacy” and the “digital citizenship” factors had a lower and higher rating, respectively, compared to the other factors. A total of 91.6 % of the students considered that digital skills are important and very important, which could be considered as highly favorable.Objetivo: Determinar las competencias digitales de los estudiantes de la maestría en Cuidados Paliativos y Manejo del Dolor de la Facultad de Medicina de la Universidad Nacional Mayor de San Marcos en el año 2022. Materiales y métodos: Investigación de diseño no experimental, descriptivo y de corte transversal. La población de estudio estuvo conformada por los alumnos de la maestría en Cuidados Paliativos y Manejo de Dolor matriculados en el año 2022. Se empleó una muestra no probabilística. Los datos se recolectaron a través de la encuesta Cuestionario de competencias digitales en educación superior (CDES), compuesta por 46 indicadores distribuidos en cinco factores, que tiene una fiabilidad de 0,96 según alfa de Cronbach. Se respetó la confidencialidad de los datos y la autonomía en las decisiones de los participantes. Resultados: Se trabajó con una muestra final de 59 alumnos. La edad promedio fue 38,03 años y el 76,3 % fueron mujeres. Todos los estudiantes contaban con una computadora personal y acceso a internet. El análisis descriptivo determinó un predominio de la valoración “muy importante”: 49,2 % para el factor “ciudadanía digital”; 47,5 % para el factor “comunicación y colaboración”; 45,8 % para “creatividad e innovación” y “acceso y uso de la información”; y 44,1 % para el factor “alfabetización digital”. Según el análisis global de competencias digitales, 49,2 % manifestó una valoración “muy importante" y 42,4 %, “importante”; no hubo resultados para la denominación “nada importante”. Conclusiones: Todos los estudiantes disponen de una computadora personal y cuentan con acceso a internet, lo que ratifica el creciente interés por incluir los aspectos relacionados con la competencia digital en la educación universitaria. El factor “alfabetización tecnológica” presentó menor valoración, mientras que el factor “ciudadanía digital” tuvo mayor valoración. El 91,6 % de estudiantes valora la competencia digital entre importante y muy importante, lo que podría considerarse como muy favorable

Evaluating Nuclei Concentration in Amyloid Fibrillation Reactions Using Back-Calculation Approach

Background: In spite of our extensive knowledge of the more than 20 proteins associated with different amyloid diseases, we do not know how amyloid toxicity occurs or how to block its action. Recent contradictory reports suggest that the fibrils and/or the oligomer precursors cause toxicity. An estimate of their temporal concentration may broaden understanding of the amyloid aggregation process. Methodology/Principal Findings: Assuming that conversion of folded protein to fibril is initiated by a nucleation event, we back-calculate the distribution of nuclei concentration. The temporal in vitro concentration of nuclei for the model hormone, recombinant human insulin, is estimated to be in the picomolar range. This is a conservative estimate since the back-calculation method is likely to overestimate the nuclei concentration because it does not take into consideration fibril fragmentation, which would lower the amount of nuclei Conclusions: Because of their propensity to form aggregates (non-ordered) and fibrils (ordered), this very low concentration could explain the difficulty in isolating and blocking oligomers or nuclei toxicity and the long onset time for amyloid diseases

Multi-causal and integrated assessment of sustainability: the case of agriculturization in the Argentine Pampas

Assessing the sustainability of complex development processes requires multi-causal and integrated analyses. We develop a system-based methodology, rooted in interdisciplinary discussion and consensus building between 15 experts, to construct a multi-causal diagram which examines the sustainability of the Argentine Pampas´ process of agriculturization. The resulting diagram includes 25 factors and provides a big-picture of the multiple dimensions and interrelations affecting sustainability. According to this examination, the increasing concentration of production and the incorporation of technological innovations, triggered by economic and institutional factors, are the cause of environmental distresses and social changes, whose consequences for sustainability are still highly disputed. Nevertheless, the symptoms of both environmental and social unsustainability are more evident in the case of the extra-Pampean regions than in the Pampas. This suggests that the Pampean agriculture model should not be transferred to these regions without substantial modifications. The experts did not reach consensus on whether the agriculturization process is overall sustainable or unsustainable. Lack of consensus revolved mainly around opposing perspectives regarding the significance of the threats to environmental sustainability. The magnitude of socio-distributive unbalance and loss of rural jobs were also contentious. Yet, the paper shows how the exercise of building a joint causal diagram was undoubtedly helpful for linking piece-meal disciplinary facts, brought in from all fronts, into a comprehensive and coherent picture.Facultad de Ciencias Naturales y MuseoCentro de Estudios Parasitológicos y de Vectore

“Deficiencia de vitaminas en pacientes con obesidad mórbida”

El obeso mórbido no es un paciente bien nutrido. Aunque tiene depósitos excesivos de energía en forma de grasa, puede tener carencias nutritivas clínicas o subclínicas por seguir dietas desequilibradas o demasiado restrictivas durante períodos prolongados de tiempo

A Mitochondrial Kinase Complex Is Essential to Mediate an ERK1/2-Dependent Phosphorylation of a Key Regulatory Protein in Steroid Biosynthesis

ERK1/2 is known to be involved in hormone-stimulated steroid synthesis, but its exact roles and the underlying mechanisms remain elusive. Both ERK1/2 phosphorylation and steroidogenesis may be triggered by cAMP/cAMP-dependent protein kinase (PKA)-dependent and-independent mechanisms; however, ERK1/2 activation by cAMP results in a maximal steroidogenic rate, whereas canonical activation by epidermal growth factor (EGF) does not. We demonstrate herein by Western blot analysis and confocal studies that temporal mitochondrial ERK1/2 activation is obligatory for PKA-mediated steroidogenesis in the Leydig-transformed MA-10 cell line. PKA activity leads to the phosphorylation of a constitutive mitochondrial MEK1/2 pool with a lower effect in cytosolic MEKs, while EGF allows predominant cytosolic MEK activation and nuclear pERK1/2 localization. These results would explain why PKA favors a more durable ERK1/2 activation in mitochondria than does EGF. By means of ex vivo experiments, we showed that mitochondrial maximal steroidogenesis occurred as a result of the mutual action of steroidogenic acute regulatory (StAR) protein –a key regulatory component in steroid biosynthesis-, active ERK1/2 and PKA. Our results indicate that there is an interaction between mitochondrial StAR and ERK1/2, involving a D domain with sequential basic-hydrophobic motifs similar to ERK substrates. As a result of this binding and only in the presence of cholesterol, ERK1/2 phosphorylates StAR at Ser232. Directed mutagenesis of Ser232 to a non-phosphorylable amino acid such as Ala (StAR S232A) inhibited in vitro StAR phosphorylation by active ERK1/2. Transient transfection of MA-10 cells with StAR S232A markedly reduced the yield of progesterone production. In summary, here we show that StAR is a novel substrate of ERK1/2, and that mitochondrial ERK1/2 is part of a multimeric protein kinase complex that regulates cholesterol transport. The role of MAPKs in mitochondrial function is underlined

Hormone-Dependent Expression of a Steroidogenic Acute Regulatory Protein Natural Antisense Transcript in MA-10 Mouse Tumor Leydig Cells

Cholesterol transport is essential for many physiological processes, including steroidogenesis. In steroidogenic cells hormone-induced cholesterol transport is controlled by a protein complex that includes steroidogenic acute regulatory protein (StAR). Star is expressed as 3.5-, 2.8-, and 1.6-kb transcripts that differ only in their 3′-untranslated regions. Because these transcripts share the same promoter, mRNA stability may be involved in their differential regulation and expression. Recently, the identification of natural antisense transcripts (NATs) has added another level of regulation to eukaryotic gene expression. Here we identified a new NAT that is complementary to the spliced Star mRNA sequence. Using 5′ and 3′ RACE, strand-specific RT-PCR, and ribonuclease protection assays, we demonstrated that Star NAT is expressed in MA-10 Leydig cells and steroidogenic murine tissues. Furthermore, we established that human chorionic gonadotropin stimulates Star NAT expression via cAMP. Our results show that sense-antisense Star RNAs may be coordinately regulated since they are co-expressed in MA-10 cells. Overexpression of Star NAT had a differential effect on the expression of the different Star sense transcripts following cAMP stimulation. Meanwhile, the levels of StAR protein and progesterone production were downregulated in the presence of Star NAT. Our data identify antisense transcription as an additional mechanism involved in the regulation of steroid biosynthesis