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Trabajo presentado en el 8th Symposium on Hydrogen, Fuel Cells and Advanced Batteries, celebrado en Buenos Aires (Argentina), del 10 al 13 de julio de 2022, Among all types of energy storage systems (ESS), vanadium redox flow batteries (VRFB) stand out for their high efficiency (70-90 %), long life cycle, safety and the possibility to decouple both energy and power sizes [1]. One of the main challenges in the study and analysis of VRFB consists on the correct caracterization of its performance through mathematical models. The importance of developing mathematical models is reflected in the literature, where numerous studies widely validated and referenced can be found, such as the electrochemical model developed by M. Skyllas-Kazacos [2], who pioneered the use of vanadium in redox flow batteries. Models can be classified as static or dynamic, depending on whether the effect of time is taken into acount, and as distributed or lumped parameter models, depending on the space dimension [3]. Tools as COMSOL are used to analyze and develop distributed parameter models, to study effects of flow design, components materials or degradation mechanisms [4]. However, for control purposes, the distributed models are rarely used due to its complexity and relevant computational cost, both in resources and time. For that reason, a vast majority of works in the literature concerning VRFB control, use lumped parameters models. Most of these lumped parameters models use different hypothesis to relax the problem, facilitating its understanding and analysis. This is the case of Skyllas-Kazacos electrochemical models mentioned, where the same flow rate is considered in both semicells,same species concentration inside the cell and tanks, as well as a constant temperature to estimate the open circuit voltage (OCV) by means of the Nernst equation [5]. Therefore, it is necessary to develop an analysis in order to define which variables and parameters will be modelled, and under which assumptions. Thus, in this work, a complete model that considers the most important effects of a VRFB is presented. It can be divided into four submodels, according to the previous parameters, which are: electrochemical, voltage, thermal and hydraulic ones. This model has been developed in a Matlab-Simulink environment as a tool to analyze the performance of a VRFB in a wide range of possibilities, examining the behaviour of the species and the voltage, temperature and pressure variables, incorporating some improvements with respect to other works. For all submodels, a clear distinction is made between both sides of the system (catholyte and anolyte semicells), not only in terms of dimensions and flow rates, but also on the initial conditions., This research is part of the CSIC program for the Spanish Recovery, Transformation and Resilience Plan funded by the Recovery and Resilience Facility of the European Union, established by the Regulation (EU) 2020/2094, CSIC Interdisciplinary Thematic Platform (PTI+) Transición Energética Sostenible+ (PTI-TRANSENER+) and the Spanish Ministry of Economy and Competitiveness under Project DOVELAR (ref. RTI2018-096001-B-C32).

Seminario Pontificia Universidad Católica de Chile

Estudio de las comunidades de crustáceos decápodos de la plataforma continental de la Isla de Alborán, asociadas a fondos de maërl o rodolitos y de "cascajo" o biclastos. El presente estudio se enmarca dentro del proyecto LIFE + INDEMARES, uno de cuyos objetivos ha sido la caracterización de las biocenosis de los hábitats esenciales o vulnerables de la plataforma submarina de la isla de Alborán (Ref.: Fundación Biodiversidad, FB 05/2011, Universidad de Málaga). Los fondos de cascajo han resultado ser más ricos, diversos y con una mayor equirrepartición que los de maërl y con agunas especies raras o muy poco frecuentes, ya sea debido al tipo de fondo - hábitat y/o características hidrológicas de la zona. Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech.

En este trabajo se ha realizado un estudio para evaluar la calidad y seguridad microbiológica de canales de pollo envasadas en cinco mataderos de pollos ubicados en los municipios San Francisco, Maracaibo y Mara, del estado de Zulia, Venezuela (plantas A, B, C, D y E), para determinar la presencia de Salmonella spp. y el recuento de aerobios mesófilos, basándonos en legislación vigente (Norma Venezolana Covenin 2343-86 pollo beneficiado). Se han analizado 30 muestras de canales de pollo envasado. Asimismo, se han tomado muestras en tres áreas del procesado: evisceración, preenfriamiento y enfriamiento. Se analizaron un total de 150 muestras (30 de contenido intestinal, 90 de canales y 30 de agua de los tanques). Se detectó la presencia de Salmonella spp. en el 60% de las canales envasadas (IC95%, 42,47-77,53%), mientras que un 40 por ciento (IC95% 22,47-57,53%) superó los límites tolerables para aerobios mesófilos. Se comprueba que la evisceración es un punto crítico, debido al alto grado de contaminación de los animales que llegan al matadero. De igual modo, se han detectado contaminaciones cruzadas en el preenfriamiento y enfriamiento de las canales, imposibilitando la eliminación de estos agentes en el producto final... A study to assess the microbiological quality and safety of chicken carcasses packaged in five chicken slaughterhouses located in San Francisco, Mara and Maracaibo, Zulia State, Venezuela (designed as plants A, B, C, D and E) to detect the presence of Salmonella spp. and count aerobic mesophilic bacteria, based on the Norma Venezolana Covenin 2343-86 pollo beneficiado en Venezuela, was carried out. A total of 30 packaged chicken carcasses were sampled. Also, three areas of processing: evisceration, pre-chiller and chiller were analyzed. A total of 150 samples (30 intestinal content, 90 carcass and 30 samples of water) were obtained. Of the thirty packed chicken carcasses analyzed, we detected the presence of Salmonella spp. in 18 (60%, 95% CI, 42.47-77.53), and the number of carcasses that exceeded tolerable limits for aerobic mesophilic microorganisms was 40 percent (95% CI: 22.47-57.53). The evisceration is considered a critical point of the process; due to the high degree of contamination of the animals arrive at the slaughterhouse. Also, along the processing (pre-chiller and chiller) cross contamination is observed, avoiding the elimination of these microorganisms in the final product. According to the results, the implementation of monitoring and control of Salmonella spp. in primary production; review the sanitary conditions of the slaughterhauses, and the adoption of codes of good practice on the staff responsible for the holdings, transport and slaughter are recommended. Finally we recommend reviewing the Covenin Norma Venezolana in relation to sampling pressure, type of samples, diagnostic techniques and results interpretation according to international standards to facilitate trade of meat products with maximum health guarantees...

Diabetes mellitus is a health concern of the first order, given the high level of associated morbidity and mortality. The objective, in order to slow down the advance of its complications before they become irreversible, is based on correct metabolic control. The high rate of morbidity associated with the surgery of the vascularized pancreas transplant and the high index of rejection have for three decades formed an obstacle to this being considered a valid alternative in the treatment of these patients. Nowadays the pancreas transplant has come to occupy a key position, thanks to the new regimes of immunosuppression and to the perfection of surgical techniques. In this article we review the evolution of the pancreas transplant from its beginnings to its present state.

The effects of endogenous Plasma Renin Substrate (PRS) on the relationship between Plasma Renin Activity (PRA) and the Plasma Renin Concentration (PRC) have been studied in hyperthyroid rats, by I-triiodothyronine (T3) administration and in hypothyroid rats, by propylthiouracil (PTU) treatment, to clarify if PRA changes are an adequate index for evaluating the renin-angiotensin changes during the alterations in the thyroid function. Although in experimental situations studied the induced variation on PRC explains a 62 per cent of the changes in PRA, finding a good lineal correlation between both parameters (r = 0.79, P less than 0.001). Not only does PRS play an important role on the kinetic of the enzymatic reaction but also explains jointly with PRC up to a 85 per cent of PRA alterations. PRS changes become more important during thyrotoxicosis where they limit in a higher degree the velocity of reaction due to inverse relationship between PRC and PRS (r = 0.74, P less than 0.001).

When hypothyroidism is induced surgically in early steps of development in the rat, an increase in serum aldosterone concentration (AC), in absence of changes in plasma renin activity (PRA), is observed. In contrast, in propylthiouracil (PTU) induced hypothyroidism, in adult animals, both AC and PRA decrease. Potassium iodide (KI) or triiodo-L-thyronine (T3) administration to thyroidectomized rats restores AC to normal levels, increasing PRA during the latter treatment. A close relationship between AC and plasma renin concentration (PRC) is observed in these experimental situations. The decrease in urinary aldosterone concentration (ACu), and the relation found between AC/ACu ratio and T3 concentration, suggest that metabolic clearance of aldosterone might be related to peripheric T3 levels in thyroidectomized animals, treated with KI or T3. These observations support the hypothesis, previously reported, which suggests different mechanisms involved in the control of aldosterone and renin release during the two different types of hypothyroidism.

The basal levels of angiotensin I and kinetic parameters of renin-angiotensin system were studied under control, hyper- and hypothyroidism conditions. The serum levels of triiodothyronine (T3) and thyroxine (T4) and plasma angiotensin II have been measured radioimmunoassay. Hyperthyroidism was induced by 5.5 micrograms/200 g of T3 or 100 micrograms/200 g of T4 administration for 12 days, and hypothyroidism by propylthiouracil (PTU) administration of 1 mg/200 g for 12 days. Basal levels of angiotensin I and plasma renin activity (PRA) increased after T3 injection, were not altered by T4 and decreased after PTU administration. T3 and T4 induced an increase in plasma renin concentration (PRC), while PTU induced a decrease in PRC. Plasma renin substrate (PRS) decreased in hyperthyroid rats and was unchanged by experimentally induced hypothyroidism. A good correlation between T3 serum levels and PRA was found, but there was no such correlation between T4 serum levels and PRA.

The relationship between the renal function and some components of the renin-angiotensin system has been studied in hypothyroid rats thyroidectomized surgically at different periods of their life. Changes in plasma renin concentration (PRC) depending on the period hypothyroidism were induced. Results showed that the renin release control could result from an equilibrium between the reduced beta-adrenergic activity and the marked natriuresis observed in hypothyroidism. A reduction in plasma angiotensinogen concentration (PAC), due to a decrease in its hepatic production, was observed in thyroidectomized animals. PAC reduction was independent of the hypothyroidism induction period. Alterations in plasma renin activity (PRA) were a consequence of PRC and PAC changes in thyroidectomized animals, as an increase in fractional sodium excretion (FENa) time course dependent, was found in these rats.

The effects of endogenous Plasma Renin Substrate (PRS) on the relationship between Plasma Renin Activity (PRA) and the Plasma Renin Concentration (PRC) have been studied in hyperthyroid rats, by I-triiodothyronine (T3) administration and in hypothyroid rats, by propylthiouracil (PTU) treatment, to clarify if PRA changes are an adequate index for evaluating the renin-angiotensin changes during the alterations in the thyroid function. Although in experimental situations studied the induced variation on PRC explains a 62 per cent of the changes in PRA, finding a good lineal correlation between both parameters (r = 0.79, P less than 0.001). Not only does PRS play an important role on the kinetic of the enzymatic reaction but also explains jointly with PRC up to a 85 per cent of PRA alterations. PRS changes become more important during thyrotoxicosis where they limit in a higher degree the velocity of reaction due to inverse relationship between PRC and PRS (r = 0.74, P less than 0.001).

This paper describes the studies carried out to select the most suitable lipase as catalyst for the esterification of polyglycerol with polyricinoleic acid to yield polyglicerol polyricinoleate (PGPR), a value-added, bio-based food emulsifier. The enzymes assayed were lipases from Rhizopus arrhizus, Rhizopus oryzae and Mucor javanicus, previously selected because of their suitable activity and moderate cost. First, the reaction was catalyzed by free lipases in a batch reactor and the influence of different operating conditions (initial water content, amount of enzyme and temperature) on the progress of the reaction was studied. Next, the three lipases were immobilized by physical adsorption on the anion exchange resin, Lewatit MonoPlus MP 64, providing derivatives with a high activity and stability. Recovery of the immobilized derivative from the reaction medium was conducted with very good yields (≥ 99 %) and no loss of activity of the derivative with successive uses was proved. Finally, a high performance reactor, operating at low pressure and a dry atmosphere, was used to synthesise PGPR using the immobilized enzymes. Both Rhizopus arrhizus and Rhizopus oryzae lipases allowed the production of a PGPR which fulfils the “specific purity criteria on food additives other than colours and sweeteners” established by the Commission of the European Communities (AV ≤ 6 mg KOH/g), with an acid value of 4.91 and 5.31 mg KOH/g respectively.

The basal levels of angiotensin I (A. I), plasma renin activity (PRA), plasma renin substrate (PRS) and plasma renin concentration (PRC) were estimated in hyperthyroid rats before and after propranolol treatment. Serum levels of triiodothyronine (T3), thyroxine (T4), angiotensin I both basal and generated by incubation of plasma samples were measured by radioimmunoassay, while, PRC and PRS were evaluated by triiodothyronine or thyroxine treatment induced a decrease in PRS and an increase in PRC whereas triiodothyronine alone produced an increase in the basal levels of angiotensin I and PRA. The propranolol in euthyroid animals not only decreased the basal levels of angiotensin I and PRA, but also prevented the PRC increase in hyperthyroid rats, while restoring at the same time the basal levels of angiotensin I and PRA.

Kinetic studies of the renin-angiotensin system (RAS) were carried out by measuring plasma renin activity (PRA), plasma renin concentration (PRC) and plasma renin substrate (PRS). Changes in this system were studied during hypothyroidism, after administration of propylthiouracil (PTU), and in thyroidectomized rats. A significant decrease in PRA and PRC was observed in those animals previously treated with PTU. However, a significant increase in PRC, and a decrease in PRS, were found in T animals, but no changes in PRA were observed. In these animals, after daily administration of potassium iodide for I week (T+KI), no changes in RAS were observed in comparison with T rats. Nevertheless, administration of daily doses of triiodo-ithyronine (T+T3) induced a significant increase in PRA, leaving PRC unaltered. In this case the changes in PRA were related to the increase in PRS after T3 treatment. These results suggest that two different mechanisms were involved in renin release, one activated in T rats and the other in pharmacological hypothyroidism.

A monolayer culture of adult rat hepatocytes was used to study the effect of various components of the renin-angiotensin-aldosterone system (angiotensin II, aldosterone and angiotensinogen), and intracellular sodium depletion (by ouabaine addition) on the angiotensinogen production rate. Normal hepatocytes synthesized linearly angiotensinogen for 6 h at a mean rate of 110 pg angiotensin I generated/mg intracellular protein each h. The addition of hydrocortisone (0.1 microM) to the culture medium significantly enhanced the angiotensinogen production after 2 h of incubation (P less than 0.05), being about 2-fold higher than normal control values at the 6th h of incubation. In contrast to this increase, the addition of angiotensin II (70 nM) to the medium produced a higher stimulatory effect on angiotensinogen synthesis, being the differences with the control significants after 1 h of incubation (P less than 0.01). At the 6th h of incubation, angiotensin II enhanced the angiotensinogen production over 2 fold in relation to the control group. No change in the angiotensinogen production rate was observed in monolayer culture of hepatocytes in the presence of aldosterone (1 microM), angiotensinogen (0.1 microM) or ouabaine (10 microM). These results provide further evidence that angiotensinogen synthesis is subject to a positive feed-back mechanism by angiotensin II, indicating that this mechanism takes place at physiological levels of plasma AII.

The changes occurring in several components of the rat renin-angiotensin system (RAS) were studied for the brief postnatal period, between the fourth and tenth week of life. The parameters were: plasma renin activity (PRA), plasma renin concentration (PRC), plasma renin substrate (PRS) and the plasma angiotensin II concentration (AII). A gradual decrease in PRA with age was noticed. Between the fourth and the eighth weeks of life, this was attributed to a corresponding decline in both PRC and PRS. However, between the eighth and tenth weeks, no changes in PRA could be detected, but PRC and PRS increased, perhaps as a consequence of the changes in renal function and the AII increase observed. In this second period, simultaneously with the RAS changes described, there was reduced sodium chloride excretion as the glomerular filtration rate (GFR) stabilized. The data presented suggest that this postnatal period is critical, in rats, for the maturation of the RAS component control mechanisms; they appear to be closely related to the development of the renal function.

The effect of the muscarinic receptors agonist carbachol (Cch) on intracellular calcium concentration ([Ca(2+)](i)) and cAMP level was studied in polarized Fischer rat thyroid (FRT) epithelial cells. Cch provoked a transient increase in [Ca(2+)](i), followed by a lower sustained phase. Thapsigargin, a specific microsomal Ca(2+)-ATPase inhibitor, caused a rapid rise in [Ca(2+)](i) and subsequent addition of Cch was without effect. Removal of extracellular Ca(2+) reduced the initial transient response and completely abolished the plateau phase. Ryanodine, an agent that depletes intracellular Ca(2+) stores through stimulation of ryanodine receptors (RyRs), had no effect on [Ca(2+)](i). However, the transitory activation of [Ca(2+)](i) was dose-dependently attenuated in cells pretreated with U73122, a specific inhibitor of phospholipase C (PLC). These data suggest that the Cch-stimulated increment of [Ca(2+)](i) required IP(3) formation and binding to its specific receptors in Ca(2+) stores. Further studies were performed to investigate whether the effect of Cch on Ca(2+) entry into FRT cells was via L-type voltage-dependent Ca(2+) channels (L-VDCCs). Nicardipine, a nonspecific L-type Ca(2+) channel blocker, decreased Cch-induced increase on [Ca(2+)](i), while Bay K-8644, an L-type Ca(2+) channel agonist, slightly increased [Ca(2+)](i) in FRT cells. These data indicate that Ca(2+) entry into these nondifferentiated thyroid cells occurs through an L-VDCC, and probably through another mechanism such as a capacitative pathway. Cch did not affect the intracellular cAMP levels, but its effects on [Ca(2+)](i) were significantly reduced when cells were pretreated with forskolin, suggesting the existence of an intracellular cross-talk between PLC and cAMP mechanisms in the regulation of intracellular Ca(2+) mobilization in neoplastic FRT cells.

Rat adrenal AT1A and AT1B receptors from transfected COS-7 cells were labelled with 125I-Angiotensin II, solubilised, and run on isoelectric focusing gels. Receptors from rat tissues were treated similarly. COS-7 cell-expressed AT1A and AT1B receptors each produced a single peak of specific radioactivity at pI 6.8. Rat liver and rat ovary tissue preparations gave peaks at pI 6.8 and 6.5, respectively. In contrast, rat adrenal tissue preparations gave four peaks at pI 7.0, 6.8, 6.5, and 6.3. The additional isoforms found in the rat adrenal tissue preparations may represent post-translationally modified or novel receptors.