New trends in modelling of breakthrough curves to remove pollutants using adsorption on advanced monoliths geometries.

This work proposes a rigorous mathematical model capable of reproducing the adsorption process in dynamic regime on advanced monoliths geometries. For this, four bed geometries with axisymmetric distribution of channels and similar solid mass were proposed. In each geometry a different distribution of channels was suggested, maintaining constant the bed dimensions of 15 cm high and 5 cm radius. The mathematical modeling includes mass and momentum transfer phenomena, and it was solved with the COMSOL Multiphysics software using mass transfer parameters published in the literature. The overall performance of the column was evaluated in terms of breakthrough (CA/CA0 = 0.1) and saturation times (CA/CA0 = 0.9). The mass and velocity distributions obtained from the proposed model show good physical consistency with what is expected in real systems. In addition, the model proved to be easy to solve given the short convergence times required (2-4 h). Modifications were made to the bed geometry to achieve a better use of the adsorbent material which reached up to 80%. The proposed bed geometries allow obtaining different mixing distributions, in such a way that inside the bed a thinning of the boundary layer is caused, thus reducing diffusive effects at the adsorbent solid-fluid interface, given dissipation rates of about 323 × 10-11 m2/s3. The bed geometry composed of intersecting rings deployed the best performance in terms of usage of the material adsorbent, and acceptable hydrodynamical behavior inside the channels (maximum fluid velocity = 35.4 × 10-5 m/s and drop pressure = 0.19 Pa). Based on these results, it was found that it is possible to reduce diffusional effects and delimit the mass transfer zone inside the monoliths, thus increasing the efficiency of adsorbent fixed beds.

Hydrothermal synthesis of a photocatalyst based on Byrsonima crassifolia and TiO2 for degradation of crystal violet by UV and visible radiation.

This work presents a one-step synthesis methodology for preparing a hydrochar (HC) doped with TiO2 (HC-TiO2) for its application on the degradation of crystal violet (CV) using UV and visible radiation. Byrsonima crassifolia stones were used as precursors along with TiO2 particles. The HC-TiO2 sample was synthesized at 210 °C for 9 h using autogenous pressure. The photocatalyst was characterized to evaluate the TiO2 dispersion, specific surface area, graphitization degree, and band-gap value. Finally, the degradation of CV was investigated by varying the operating conditions of the system, the reuse of the catalyst, and the degradation mechanism. The physicochemical characterization of the HC-TiO2 composite showed good dispersion of TiO2 in the carbonaceous particle. The presence of TiO2 on the hydrochar surface yields a bandgap value of 1.17 eV, enhancing photocatalyst activation with visible radiation. The degradation results evidenced a synergistic effect with both types of radiation due to the hybridized π electrons in the sp2-hybridized structures in the HC surface. The degradation percentages were on average 20% higher using UV radiation than visible radiation under the following conditions: [CV] = 20 mg/L, 1 g/L of photocatalyst load, and pH = 7.0. The reusability experiments demonstrated the feasibility of reusing the HC-TiO2 material up to 5 times with a similar photodegradation percentage. Finally, the results indicated that the HC-TiO2 composite could be considered an efficient material for the photocatalytic treatment of water contaminated with CV.

An efficient removal approach for degradation of metformin from aqueous solutions with sulfate radicals.

Metformin consumption for diabetes treatment is increasing, leading to its presence in wastewater treatment plants where conventional methods cannot remove it. Therefore, this work aims to analyze the performance of advanced oxidation processes using sulfate radicals in the degradation of metformin from water. Experiments were performed in a photoreactor provided with a low-pressure Hg lamp, using K2S2O8 as oxidant and varying the initial metformin concentration (CA0), oxidant concentration (Cox), temperature (T), and pH in a response surface experimental design. The degradation percentages ranged from 26.1 to 87.3%, while the mineralization percentages varied between 15.1 and 64%. Analysis of variance (ANOVA) showed that the output variables were more significantly affected by CA0, Cox, and T. Besides, a reduction of CA0 and an increase of Cox up to 5000 µM maximizes the metformin degradation since the generation of radicals and their interaction with metformin molecules are favored. For the greatest degradation percentage, the first order apparent rate constant achieved was 0.084 min-1. Furthermore, while in acidic pH, temperature benefits metformin degradation, an opposite behavior is obtained in a basic medium because of recombination and inhibition reactions. Moreover, three degradation pathways were suggested based on the six products detected by HPLC-MS: N-cyanoguanidine m/z = 85; N,N-dimethylurea m/z = 89; N,N-dimethyl-cyanamide m/z = 71 N,N-dimethyl-formamide m/z = 74; glicolonitrilo m/z = 58; and guanidine m/z = 60. Finally, it was shown that in general the toxicity of the degradation byproducts was lower than the toxicity of metformin toward Chlamydomonas reinhardtii.

Electrocatalytic activity of calcined manganese ferrite solid nanospheres in the oxygen reduction reaction.

In this study, we synthesized MnFe2O4 solid nanospheres (MSN) calcined at different temperatures (200-500 °C) and MSN-based materials mixed with carbon black, for their use as electrocatalysts in the oxygen reduction reaction (ORR) in alkaline medium (0.1 M KOH). It was demonstrated that the calcination temperature of MSN material determined its chemical surface composition and microstructure and it had an important effect on the electrocatalytic properties for ORR, which in turn was reflected in the performance of MSN/CB-based electrocatalysts. The study revealed that the presence of Mn species plays a key role in the ORR activity. Among tested, MSN200/CB and MSN350/CB exhibited the best electrochemical performances together with outstanding stability.

Effect of operational parameters on photocatalytic degradation of ethylparaben using rGO/TiO2 composite under UV radiation.

The objective of this study was to analyze the influence of different operational variables (catalyst loading, initial EtP concentration, medium pH, the presence of anions and radical scavengers) on the performance of ethylparaben (EtP) photodegradation catalyzed with an rGO/TiO2 composite. EtP was selected for study after analyzing the effect of paraben chain length on its catalytic photodegradation, finding that the photodegradation rate constant values of methyl-, ethyl-, and butyl-paraben are 0.050, 0.096, and 0.136 min-1, respectively. This indicates that the photodegradation rate constant of parabens is higher with longer alkyl chain, which augments its oxidation capacity. The percentage removal of EtP at 40 min increases from 66.3 to 98.6 % when the composite dose rises from 100 to 700 mg/L; however, an additional increase in the composite dose to 1000 mg/L does not substantively improve the photodegradation rate or percentage EtP removal (98.9 %). A rise in the initial EtP concentration from 15 to 100 mg/L reduces the percentage of degradation from 100 to 76.4 %. The percentage EtP degradation is lower with higher solution pH. The presence of HCO3- or Cl- anions in the medium reduces the degradation performance. Results obtained using positive hole and hydroxyl radical scavengers demonstrate that positive holes play an important role in EtP degradation. No degradation product evidences toxicity against the cultured human embryonic kidney cell line HEK-293.

Oxidation of sulfonamides by ferrate(VI): Reaction kinetics, transformation byproducts and toxicity assesment.

This study was aimed at the degradation of sulfonamides (SNs) via oxidation with Fe(VI). The reaction kinetics, identification of degradation byproducts and their toxicity were investigated. The pH solution and Fe(VI) loading had significant effects on the degradation of the sulfonamides. The maximum degradation rate occurred at pH 3.0 with a 6:1 ratio Fe(VI): sulfonamide, obtaining 100% degradation of 15 mg L-1 SN within 5 min. Although Fe(VI) also showed an appreciable reactivity towards SNs (kapp = 9.85-19.63 × 102 M-1 s-1) at pH 7. The influence of solution pH on the values of kapp can be explained considering the specific reaction between Fe(VI) and SNs. Degradation rates are also influenced by the presence of inorganic ions in different water matrixes. For this reason, ions present in groundwater enhanced the SNs degradation through a synergistic effect among carbonates, sulfates and Fe(VI). Degradation byproducts identified, through UPLC analysis, allowed us to proposed three degradation pathways depending on pH. At acid pH there is a cleavage of C-S and S-N bonds. At neutral pH nitroso and nitro-derivates are formed. At basic pH hydroxylation is the main reaction. The cytotoxicity assay of HEK-293 and J774 cell lines exposed to Fe(VI) indicated that transformation byproducts had a lower toxicity than SNs as baseline products. Accordingly, this research suggests that Fe(VI) can act as a chemical oxidant to remove SNs antibiotics and it can be used to treat antibiotic pollution in wastewater.

Degradation of the diuretic hydrochlorothiazide by UV/Solar radiation assisted oxidation processes.

The objective of this study was to analyse the effectiveness of advanced oxidation processes (AOPs) with Solar and UV radiation (UV/H2O2, UV/K2S2O8) for the degradation of hydrochlorothiazide (HCTZ), a widely used diuretic drug, in aqueous solution focusing on the influence of four experimental parameters: initial concentration of HCTZ, solution pH, nature of the water matrix, and initial concentration of radicals. The obtained results showed that using both kinds of direct photolysis (UV and Solar), the percentage of degraded HCTZ was low, but there was a decrease in the degradation rate favored by the increase of the initial concentration of this pollutant. In addition, the degradation rates were higher at acid pHs. With regard to the nature of water, the degradation rate varied in the order: ultrapure > superficial > tap water. This is due to the presence of organic and inorganic matter (bicarbonates, nitrates, and chlorides) in surface and tap water, that react with the radicals generated, which reduces the availability of radical species, generating competitive kinetics. The presence of radical-promoter species increased the degradation rate of the pollutant, reaching a degradation of 100% of HCTZ after 20 min of treatment. The results obtained point out that the degradation rate was higher in the presence of HO radicals. This behavior was attributed to the higher oxidation power of HO versus radicals. The determination of the degradation by-products led to structures very similar to the parent compound. For example, the corresponding hydroxylated dechlorinated derivative of HCTZ was found in all the systems used. The cytotoxicity test showed that these byproducts have a lower toxicity than the original product. Finally, the economic viability study confirmed that the UV/K2S2O8 system has the lowest cost.

Halide removal from water using silver doped magnetic-microparticles.

This study proposes the use of new materials based on core-shell structure magnetic microparticles with Ag0 (Ag(0)-MPs) on their surface to remove bromides and chlorides from waters intended for human consumption. Hydrogen peroxide was used as oxidizing agent, Ag(0)-MPs is thereby oxidized to Ag (I)-MPs, which, when in contact with Cl- and Br- ions, form the corresponding silver halide (AgCl and AgBr) on the surface of Ag-MPs. The concentration of Cl- and Br- ions was followed by using ion selective electrodes (ISEs). Silver microparticles were characterized by high-resolution scanning electron microscopy and X-ray photoelectron spectroscopy, while the presence of AgCl and AgBr on Ag-MPs was determined by microanalysis. We analyzed the influence of operational variables, including: hydrogen peroxide concentration in Ag-MP system, medium pH, influence of Cl- ions on Br- ion removal, and influence of tannic acid as surrogate of organic matter in the medium. Regarding the influence of pH, Br-and Cl- removal was constant within the pH range studied (3.5-7), being more effective for Br- than for Cl- ions. Accordingly, this research states that the system Ag-MPs/H2O2 can remove up to 67.01% of Br- ions and 56.92% of Cl- ions from water (pH = 7, [Ag-MPs]0 = 100 mg L-1, [H2O2]0 = 0.2 mM); it is reusable, regenerated by radiation and can be easily removed by applying a magnetically assisted chemical separation process.

Removal of bisphenols A and S by adsorption on activated carbon clothes enhanced by the presence of bacteria.

This study investigated the adsorption of two endocrine-disrupting chemicals, bisphenol A (BPA) and S (BPS), from water using activated carbon clothes (ACCs), as-received and oxidized, in the absence and presence of bacteria, analyzing both kinetic and equilibrium adsorption data. Kinetic study of the different systems showed that the adsorption rate was affected both by the oxidation of the adsorbent and by the presence of bacteria. Bisphenol adsorption kinetics followed a second-order kinetic model, with rate constants between 0.0228 and 0.0013 g min-1 mol-1. ACC was a much better adsorbent of E. coli compared to granular activated carbons, achieving 100% adsorption at 24 h. ACC oxidation reduced the adsorption capacity and the adsorbent-adsorbate relative affinity due to the decrease in carbon surface hydrophobicity. Conversely, the presence of bacteria in aqueous solution increased the ACC surface hydrophobicity and therefore enhanced the adsorption capacity of BPA and BPS on ACC, which was 33% and 24%, respectively. In all cases, more BPS than BPA was removed due to the greater dipolar moment of the former. Results found show that activated carbon clothes in the presence of bacteria can be an adequate process to remove bisphenol A and S from different aqueous systems.

Photocatalytic oxidation of diuron using nickel organic xerogel under simulated solar irradiation.

In this study, a nickel organic xerogel (X-Ni) was used as semiconductor photocatalyst for the degradation of the herbicide diuron (DRN) in aqueous solution. The main objective of this work was to analyze and compare the effectiveness of solar irradiation to remove DRN from water both by direct photolysis and photocatalytic degradation. We examined the influence of the initial concentration of the herbicide, the solution pH, the presence of different ions in the medium, the chemical composition of the water, and the presence of a photocatalyst, after 240 min of irradiation. Direct photolysis achieved a low percentage of DRN degradation but was favored: i) by a reduction in the initial concentration of the herbicide (from 35.6% to 79.0% for 0.150 × 10-3 mol/L and 0.021 × 10-3 mol/L of DRN, respectively) and ii) at solution pHs at which diuron is positively charged (78.6% for pH 2 and 50.4% for pH 7), as suggested by DFT calculations carried out for DRN and its protonated form (DRN-H+). The corresponding mono-demethylated DRN derivative, 1-(3,4-dichlorophenyl)-3-methylurea (DCPU), was identified as a DRN degradation byproduct. In addition, the presence of certain anions in the medium significantly affected the overall degradation process by direct photolysis, due to the additional generation of HO radicals. We highlight that the presence of X-Ni considerably improved the photodegradation process under solar irradiation. The photocatalytic degradation rate constant was directly proportional to the xerogel concentration, because an increase in catalyst dose produced an increase in surface active sites for the photodegradation of DRN, enhancing the overall efficiency of the process. Thus, when 4167 mg/g of X-Ni was added, the DRN removal rate was 3-fold higher and both percentage of degradation and mineralization increased 88.5% with respect to the results obtained by direct photolysis.

Lanthanum-doped silica xerogels for the removal of fluorides from waters.

The objective of this study was to determine the influence of different operational variables on fluoride (F-) removal from waters using lanthanum (La)-doped silica xerogels and the mechanisms involved in this process. Accordingly, four xerogels were synthesized, one acting as blank (X-B), two doped with LaCl3 and dried at different temperatures (X-LaCl and X-LaCl-M), and a fourth doped with La2O3 (X-LaO). The results show that fluorides are only removed when La-doped xerogels are utilized. In addition, X-LaCl yielded the highest adsorption capacity, removing 28.44% of the initial fluoride concentration at a solution pH of 7. Chemical characterization of materials confirmed that fluoride removal from waters is due to the precipitation of LaF3 on the surface of La-doped xerogels. The presence of dissolved organic matter on the aqueous solution also reduce the removal capacity of La xerogels. Finally, analysis of the influence of solution pH revealed that the adsorption capacity of all xerogels was highest at a solution pH of 7.

Afectación cardiovascular en el síndrome de Loeys-Dietz / Cardiovascular involvement in Loeys-Dietz syndrome

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La Unidad de Cardiología Pediátrica del Hospital Infantil Universitario Miguel Servet de Zaragoza / Pediatric Cardiology Unit of the Hospital Infantil Universitario Miguel Servet of Zaragoza

La cardiología pediátrica es la subespecialidad de la Pediatría que se ocupa del estudio y asistencia al niño con patología congénita o adquirida del sistema cardiovascular, abarcando las diferentes edades desde el feto, el lactante y el nño, hasta el adulto con cardiopatía congénita. El Hospital Universitario Miguel Servet de Zaragoza, cuenta con una Unidad de Cardiología Pediátrica con amplia tradición y experiencia, de referencia para una amplia çarea compuesta por toda la Comunidad Autonoma de Aragón, gran parte de la Comunidad Autonoma de La Rioja, y zonas limítrofes de las Comunidades de Castilla-Leon y Castilla—La Mancha, con una población de ú1.720.292 habitantes segun datos de 2011 del Instituto Nacional de Estadistica. Se trata de una Unidad Terciaria, capacitada y dotada para la atención integral al niño cardiópata con todos los medios diagnósticos y terapéuticos disponibles en la actualidad, coordinada con la Unidad de Cirugía Cardíaca Infantil, y en colaboración con las Unidades de Neonatología y Cuidados Intensivos Pediátricos. En este artículo, revisamos la actividad de la Unidad de Cardiologia Pediátrica del Hospital Miguel Servet, detallando la cartera de servicios, las características de la actividad asistencial y otros aspectos de la Unidad (AU)

Paediatric Cardiology is a paediatric subspecialty in charge of the study and care of the child with acquired or congenital vascular system pathology, across the different life periods, from the foetus, to the infant, child and adults with congenital heart disease. The Universitary Hospital Miguel Servet has a Paediatric Cardiology Unit with broad tradition and experience, receiving patients from a broad reference area, the whole Comunidad Autónoma de Aragón, a great part of the Comunidad Autónoma de La Rioja and border regions of Castilla-Leon and Castilla—La Mancha, with a population near 1,720,292 inhabitants (data from Instituto Nacional de Estadistica, year 2011). It is a tertiary Unit, with capacity for integral care to the child with heart disease, with every diagnostic and therapeutic possibility, and closely related with other units, as the Paediatric Cardiac Surgery Unit, the Paediatric Intensive Care Unit and the Neonatology Unit. On this report, we review the activity of the Paediatric Cardiology Unit of the Universitary Hospital Miguel Servet, listing the services offer and assistential activity characteristics (AU)

Constricción precoz del ductus arterioso / Premature constriction of the ductus arteriosus

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Taponamiento cardíaco: valor de la ecocardiografía en una Unidad de Cuidados Intensivos Pediátricos / Cardiac tamponade: Role of echocardiography in a Pediatric Intensive Care Unit

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Development and validation of the Spanish Hazard Perception Test.

OBJECTIVE: The aim of the current study is to develop and obtain valid evidence for a hazard perception test suitable for the Spanish driving population. To obtain valid evidence to support the use of the test, the effect of hazardous and quasi-hazardous situations on the participants' hazard prediction is analyzed and the pattern of results for drivers with different driving experience--that is, learner, novice, and expert drivers and reoffender vs. nonoffender drivers--is compared. Potentially hazardous situations are those that develop without involving any real hazard (i.e., the driver did not actually have to decelerate or make any evasive maneuver to avoid a potential collision). The current study analyzed repeat offender drivers attending compulsory reeducation programs as a result of reaching the maximum number of penalty points on their driving license due to repeated violations of traffic laws. METHOD: A new video-based hazard perception test was developed, using a total of 20 hazardous situation videos plus 8 quasi-hazardous situation videos. They were selected from 167 recordings of natural hazards in real Spanish driving settings. RESULTS: The test showed adequate psychometric properties and evidence of validity, distinguishing between different types of drivers. Psychometric results confirm a final version of the hazard perception test composed of 11 video clips of hazards and 6 video clips of quasi-hazards, for which an overall Cronbach's alpha coefficient of.77 was obtained. A lack of ability to detect quasi-hazards and distinguish them from hazardous situations was also found for learner, novice, and reoffender drivers. Learner drivers obtained lower average scores than novice and experienced drivers with the hazardous situation videos, and learner drivers obtained lower average scores than experienced drivers with the quasi-hazardous situation videos, suggesting that the ability to correctly identify hazardous traffic situations may develop early by accumulating initial driving experience. However, the ability to correctly identify quasi-hazardous situations may develop later with the accumulation of further driving experience. Developing this ability is also difficult for reoffender drivers. CONCLUSION: The test has adequate psychometric properties and is useful in distinguishing between learner, novice, and expert drivers. In addition, it is useful in that it analyzes the performance of both safe and unsafe drivers (reoffenders who have already lost their driving license).