52 research outputs found

    Evaluacion de las propiedades fisicas y mecanicas de la madera de olivillo (Aetoxicon puctatum) de la Region del Maule

    Get PDF
    83 p.El siguiente estudio consiste en la evaluación de las propiedades físicas y mecánicas de la madera nativa de olivillo proveniente de tres sectores de la región del Maule, Molina, Empedrado y Linares. Con el objetivo de entregar mayor información y complementar la ya existente en fomento de una especie nativa de la región, para una mejor utilización de esta madera. En las propiedades físicas son analizados la densidad, contracción radial y tangencial y el contenido de humedad. De cada sector son distintos los diámetros y cantidad de anillos de crecimiento, obteniendo 36 probetas en total, 12 por sector.Las propiedades mecánicas a estudiar son dureza con 21 probetas, compresión paralela y perpendicular, con 36 y 18 probetas respectivamente y flexión 18 probetas. El número de probetas en este caso resultó ser variable debido a las características del material. Los ensayos fueron realizados en el Laboratorio del Centro Tecnológico del Álamo en la Universidad de Talca. Las trozas provenientes de los tres sectores son procesadas en el Centro Regional de Tecnología en Industrias de la Madera (CERTIM) ubicado en la Universidad de Talca hasta obtener las probetas. Los pasos a seguir para la realización de los ensayos se encuentran en las normas chilenas por lo que las probetas deben estar acondicionadas a un contenido de humedad del 12%. Debido a esto se secan las probetas a una temperatura muy baja y se llevan a cámara de clima por algún tiempo. A traves de un análisis descriptivo se analizan las propiedades físicas y mecánicas y con análisis estadistico las físicas y una mecánica correspondiente a compresión paralela.Los análisis estadísticos demuestran que no existe diferencia significativa entre los distintos sectores. Las propiedades resultan similares a lo que dice la referencia, clasificándola como una madera densidad media, de clase mediana que puede ser utilizada para muebles, revestimientos y tableros./ SUMMARY: The following study is the evaluation of the physical and mechanical properties of wood of native olivillo from three areas of the Maule region, Molina Linares and Empedrado. With the main purpuse to give and to complement the information already existing of the a native species in order to make it more valueble for a better use of the wood. In the physical properties the density, radial contraccion and tangencial and moisture content are analyzed. Of sector the diameters are different and tha number of growing rings, giving a total of 36 samples, 12 per sector. The mechanical properties to study are hardness with 21 samples, compression parallel and perpendicular, with 36 and 18 samples respectively and flexibility 18 samples. The number of samples in this case turned out to be variable due to the characteristics of the material. The trials were carried out in the Laboratory of the Alamo Technological Center in the Universidad de Talca. The logs coming from the three sectors are processed in the Centro Regional de Tecnología en Industrias de la Madera (CERTIM) located in the Universidad de Talca until obtaining the samples. The steps to follow for the execution of the trials are found in the chilenas norms for which the samples should be conditioned to a content of humidity of the 12%. Due to this the samples are dried to a very low temperature and they are taken to a camera of climate for a period. The physical and mechanical properties a descriptive analysis are analyzed and with a statistical analysis the physical and mechanical parallelcompression properties. The statistical the analyzes brove that does not exist significant differences among the different sectors. The properties turn out to be similar to what the reference says, classifying it as an average density wood, of medium class that can be used for furniture, coverings and panel

    Catalytic hydrodechlorination as polishing step in drinking water treatment for the removal of chlorinated micropollutants

    Full text link
    This Accepted Manuscript will be available for reuse under a CC BY-NC-ND license after 24 months of embargo periodThe presence of micropollutants in fresh waters represents an important challenge for drinking water treatment plants (DWTPs). In particular, the chlorinated ones are especially harmful given their high toxicity and strong bioaccumulation potential. The aim of this work is to evaluate the feasibility of catalytic hydrodechlorination (HDC) for the removal of a representative group of chlorinated micropollutants commonly found in the source waters of DWTPs: the antibiotic chloramphenicol (CAP), the anti-inflammatory diclofenac (DCF), the antibacterial agent triclosan (TCL) and the antidepressant sertraline (SRT). The complete degradation of the isolated micropollutants (3 mg L−1) was achieved in 1 h reaction time using a Pd/Al2O3 catalyst load of 0.25 g L−1 and a H2 flow rate of 50 N mL min−1. The experimental data were properly described by a pseudo-first order kinetic equation, obtaining degradation rate constants in the range of 0.32–1.56 L gcat−1 min−1 and activation energy values within 42–52 kJ mol−1. In all cases, the final reaction products were chlorine-free compounds and thus, HDC effluents were non-toxic (<0.1 TU). Remarkably, the catalyst showed a suitable stability upon five consecutive applications. The versatility of the process was demonstrated in the treatment of the micropollutants mixture in different aqueous matrices (mineral, surface and tap waters). Strikingly, the removal rate was not affected by the presence of co-existing substances, being the micropollutants completely removed in 15 min with 1 g L−1 catalyst concentration. Finally, the potential of HDC for the removal of trihalomethanes, by-products formed along the oxidation step by chlorination in DWTPs, was also demonstratedThis research has been supported by the Spanish MINECO thorough the project CTM2016-76454-R and by the CM through the project P2018/EMT-4341. J. Nieto-Sandoval thanks the Spanish MINECO for the FPI predoctoral grant (BES-2017- 081346). M. Munoz thanks the Spanish MINECO for the Ramón y Cajal postdoctoral contract (RYC-2016-20648

    Adsorption of micropollutants onto realistic microplastics: role of microplastic nature, size, age, and NOM fouling

    Full text link
    This work aims at evaluating the role of nature, size, age, and natural organic matter (NOM) fouling of realistic microplastics (MPs) on the adsorption of two persistent micropollutants (diclofenac (DCF) and metronidazole (MNZ)). For such goal, four representative polymer types (polystyrene (PS), polyethylene terephthalate (PET), polypropylene (PP) and high-density polyethylene (HDPE)) were tested. MPs were obtained by cryogenic milling of different commercial materials (disposable bottles, containers, and trays), and fully characterized (optical microscopic and SEM images, FTIR, elemental analysis, water contact angle and pHslurry). The micropollutants hydrophobicity determined to a high extent their removal yield from water. Regardless of the MP's nature, the adsorption capacity for DCF was considerably higher than the achieved for MNZ, which can be related to its stronger hydrophobic properties and aromatic character. In fact, aromatic MPs (PS and PET) showed the highest adsorption capacity values with DCF (~100 μg g−1). The MP size also played a key role on its adsorption capacity, which was found to increase with decreasing the particle size (20–1000 μm). MPs aging (simulated by Fenton oxidation) led also to substantial changes on their sorption behavior. Oxidized MPs exhibited acidic surface properties which led to a strong decrease on the adsorption of the hydrophobic micropollutant (DCF) but to an increase with the hydrophilic one (MNZ). NOM fouling (WWTP effluent, river water, humic acid solution) led to a dramatic decrease on the MPs sorption capacity due to sorption sites blocking. Finally, the increase of pH or salinity of the aqueous medium increased the micropollutants desorptionThis research has been supported by the Autonoma University of Madrid and Community of Madrid through the project SI1-PJI-2019-00006, and by the Spanish MINECO through the project PID2019-105079RB-I00. Muñoz and J. Nieto-Sandoval thank the Spanish MINECO for the Ramón y Cajal postdoctoral contract (RYC-2016-20648) and the FPI predoctoral grant (BES-2017-081346), respectively. D. Ortiz thanks the Spanish MIU for the FPU predoctoral grant (FPU19/04816

    Degradation of widespread cyanotoxins with high impact in drinking water (microcystins, cylindrospermopsin, anatoxin-a and saxitoxin) by CWPO

    Full text link
    This Accepted Manuscript will be available for reuse under a CC BY-NC-ND license after 24 months of embargo periodThe occurrence of harmful cyanobacterial blooms has unabated increased over the last few decades, posing a significant risk for public health. In this work, we investigate the feasibility of catalytic wet peroxide oxidation (CWPO) promoted by modified natural magnetite (Fe3O4-R400/H2O2), as an inexpensive, simple-operation and environmentally-friendly process for the removal of the cyanotoxins that show the major impact on drinking water: microcystins (MC-LR and MC-RR), cylindrospermopsin (CYN), anatoxin-a (ATX) and saxitoxin (STX). The performance of the system was evaluated under ambient conditions and circumneutral pH (pH0 = 5) using relevant cyanotoxin concentrations (100–500 μg L−1). The nature of the cyanotoxins determined their reactivity towards CWPO, which decreased in the following order: MC-RR > CYN > MC-LR ≫ ATX > STX. In this sense, microcystins and CYN were completely removed in short reaction times (1–1.5 h) with a low catalyst concentration (0.2 g L−1) and the stoichiometric amount of H2O2 (2–2.6 mg L−1), while only 60–80% conversion was achieved with ATX and STX in 5 h. In these cases, an intensification of the operating conditions (1 g L−1 catalyst and up to 30 mg H2O2 L−1) was required to remove both toxins in 1 h. The impact of the main components of freshwaters i.e. natural organic matter (NOM) and several inorganic ions (HCO3−, HPO42-, SO42-) on the performance of the process was also investigated. Although the former led to a partial inhibition of the reaction due to HO· scavenging and catalyst coating, the latter did not show any remarkably effect, and the versatility of the process was finally confirmed in a real surface water. To further demonstrate the effectiveness of the catalytic system, the toxicity of both the initial cyanotoxins and the resulting CWPO effluents was measured with the brine shrimp Artemia salina. Remarkably, all CWPO effluents were non-toxic at the end of the treatment.This research has been supported by the Spanish MINECO through the project CTM-2016-76454-R and by the CM through the project P2018/EMT-4341. M. Munoz thanks the Spanish MINECO for the Ramón y Cajal postdoctoral contract (RYC-2016-20648). J. Nieto-Sandoval thanks the Spanish MINECO for the FPI predoctoral grant (BES-2017-081346

    Insights on the removal of the azole pesticides included in the EU Watch List by Catalytic Wet Peroxide Oxidation

    Full text link
    The aim of this work is to evaluate the feasibility of the Catalytic Wet Peroxide Oxidation (CWPO) process using the inexpensive and environmentally friendly Fe3O4-R400 catalyst for the removal from water of a representative group of azole pesticides recently listed in the European Union (EU) Watch Lists (penconazole (PEN), prochloraz (PCZ), tebuconazole (TEB), tetraconazole (TET), metconazole (MET)). The complete removal of these pollutants (1000 μg L−1) was achieved in <1 h reaction time under ambient conditions using a catalyst concentration of 0.5 g L−1 and the stoichiometric dose of H2O2 (3 – 5 mg L−1) at a slightly acidic pH (pH0 = 5.0). To further demonstrate the effectiveness of the process, the ecotoxicity abatement was also considered. The initial toxicity of the pesticides and the CWPO effluents were evaluated with the brine shrimp Artemia salina and the bacterium Vibrio fischeri. Remarkably, the effluents were non-toxic for V. fischeri and a decrease of more than 80% in mortality was achieved for A. salina. Furthermore, the versatility of the system was proved in real water matrices (surface water and WWTP effluent), although a slight decrease on the oxidation rate was found due to the occurrence of organic matter and inorganic salts. The reactivity of the azole pesticides was finally compared with the achieved for other groups of pollutants included in the EU Watch Lists (pharmaceuticals, hormones, and neonicotinoid pesticides). Clearly, azole compounds showed the least reactivity to oxidation, suggesting that they can be used as general indicators of the overall efficiency of the proposed catalytic system for the removal of EU Watch Lists micropollutantsThis research has been supported by the Spanish AEI through the project PID2019-105079RB-100 and by the CM, Spain through the project P2018/EMT-4341. M. Munoz, N. Lopez-Arago and J. Nieto-Sandoval thanks the Spanish AEI for the Ramón y Cajal postdoctoral contract (RYC-2016-20648), the FPI predoctoral, Spain grant (PRE2020-09452) and the FPI postdoctoral, Spain grant (BES-2017-081346), respectivel

    Catalytic hydrodehalogenation of the flame retardant tetrabromobisphenol A by alumina-supported Pd, Rh and Pt catalysts

    Full text link
    Tetrabromobisphenol A (TBBPA) is one of the most used BFRs, being characterized by a strong persistence and leading to negative effects on both the environment and human health. The aim of this work is to evaluate the feasibility of aqueous-phase catalytic hydrodehalogenation (HDH) for the fast and environmentally-friendly degradation of the brominated flame retardant TBBPA. Pd, Rh, and Pt on alumina commercial catalysts (1% wt.) were tested and reactions were performed under ambient operating conditions. TBBPA (1 mg L−1) was completely removed in short reaction times ( 95%) in 15 min using Pd/Al2O3. Nevertheless, employing Rh and Pt alumina-supported catalysts debromination of TBBPA increased progressively requiring much longer times and only 83% and 78% debromination yields were achieved after 2 h reaction, respectively. Bisphenol A (BPA), a well-known endocrine disruptor, was generated as reaction intermediate but it was further hydrogenated with both Pd and Rh catalysts, whereas it remained as reaction product with the Pt catalyst. A series reaction pathway considering both hydrodebromination and hydrogenation steps was proposed based on the obtained results. The experimental data obtained with the Pd/Al2O3 catalyst were successfully described by a pseudo-first order kinetic model, obtaining an apparent activation energy of 36 kJ mol−1. Notably, this catalyst showed a reasonable stability after three consecutive HDH run

    Application of catalytic hydrodechlorination for the fast removal of chlorinated azole pesticides in drinking water

    Full text link
    Catalytic hydrodechlorination (HDC) is regarded as a promising purifying technology for drinking water treatment. So far, it has proved to be highly effective for the removal of different groups of chlorinated micropollutants including pharmaceuticals, neonicotinoid pesticides, personal care products or chloroacetic acids. The azole pesticides, recently included in the EU Watch Lists (Decisions 2020/1161 and 2022/1307), are a group of micropollutants of particular concern for drinking water given their high toxicity, persistence, and bioaccumulation potential. In this work, the feasibility of HDC for the removal of a representative group of chlorinated azole pesticides tebuconazole (TEB), tetraconazole (TET), prochloraz (PCZ), penconazole (PEN), metconazole (MET) and imazalil (IMZ)) is demonstrated, and their reactivity is compared with that observed for other halogenated micropollutant groups. Notably, all the pesticides investigated in this work (100 μg L− 1 ) were completely dechlorinated within 30 min under ambient conditions using a 1 wt% Pd/Al2O3 catalyst concentration of 0.25 g L− 1 and a H2 feeding of 50 mL N min− 1 . The experimental data were accurately described by a pseudo-first order kinetic equation and rate constant values in the range from 1.08 to 2.60 L gcat − 1 min− 1 were obtained. These values are quite close to those achieved for the most reactive neonicotinoid pesticides and significantly higher than the obtained for chloroacetic acids and most pharmaceuticals (e.g. diclofenac, sertraline or chlorpromazine). From the identification of the generated reaction intermediates and the final nonchlorinated products, sequential reaction pathways were proposed for each pollutant. Remarkably, despite the high toxicity exhibited by the azole pesticides tested, with LC50 values within the 0.4–7.0 mg L− 1 range using A. salina, HDC effluents were non-toxic in all cases. Furthermore, the catalyst showed a remarkable stability upon three consecutive runs. Finally, the versatility of the process was demonstrated in the treatment of real aqueous matrices such as DWTP and tap water, where no significant differences were found either in terms of activity or stabilityThis research has been supported by the Spanish MINECO through project PID2019-105079RB-I00 and by the CM through project P2018/ EMT-4341. J. Nieto-Sandoval and M. Munoz thanks the MINECO for the FPI contract (BES-2017-081346) and the Ramon ´ y Cajal postdoctoral contract (RYC-2016-20648), respectively. R. B. del Olmo thanks the Operational Program for Youth Employment and the Youth Employment Initiative (YEI) of the CM for his contract as Research Assistant (PEJ2020-AI/AMB-19161

    Herpes zoster epidemiology in Latin America: A systematic review and meta-analysis

    Get PDF
    The epidemiology and burden of Herpes Zoster (HZ) are largely unknown, and there are no recent reviews summarizing the available evidence from the Latin America and Caribbean (LAC) region. We conducted a systematic review and meta-analysis to characterize the epidemiology and burden of HZ in LAC. Bibliographic databases and grey literature sources were consulted to find studies published (January 2000 ?February 2020) with epidemiological endpoints: cumulative incidence and incidence density (HZ cases per 100,000 person-years), prevalence, case-fatality rates, HZ mortality, hospitalization rates, and rates of each HZ complication. Twenty-six studies were included with most studies coming from Brazil. No studies reported the incidence of HZ in the general population. In population at higher risk, the cumulative incidence ranged from 318?3,423 cases of HZ per 100,000 persons per year of follow-up. The incidence density was 6.4?36.5 cases per 1,000 person-years. Age was identified as a major risk factor towards HZ incidence which increase significantly in people >50 years of age. Hospitalization rates ranged from 3%?35.7%. The in-hospital HZ mortality rate ranged from 0%?36%. Overall, HZ mortality rates were found to be higher in females across all age groups and countries. The incidence of HZ complications (such as post-herpetic neuralgia, ophthalmic herpes zoster, and Ramsay Hunt syndrome) was higher in the immunosuppressed compared to the immunocompetent population. Acyclovir was the most frequently used therapy. Epidemiological data from Ministry of Health databases (Argentina, Brazil, Colombia, Chile y Mexico) and Institute for Health Metrics and Evaluation?s Global Burden of Disease project reported stable rates of hospitalizations and deaths over the last 10 years. High-risk groups for HZ impose a considerable burden in LAC. They could benefit from directed healthcare initiatives, including adult immunization, to prevent HZ occurrence and its complications.Fil: Bardach, Ariel Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones en Epidemiología y Salud Pública. Instituto de Efectividad Clínica y Sanitaria. Centro de Investigaciones en Epidemiología y Salud Pública; ArgentinaFil: Palermo, Carolina. Instituto de Efectividad Clínica y Sanitaria; ArgentinaFil: Alconada, Tomás. Instituto de Efectividad Clínica y Sanitaria; ArgentinaFil: Sandoval, Macarena. Instituto de Efectividad Clínica y Sanitaria; ArgentinaFil: Balan, Darío Javier. Instituto de Efectividad Clínica y Sanitaria; ArgentinaFil: Guevara, Javier Nieto. Instituto de Efectividad Clínica y Sanitaria; ArgentinaFil: Gómez, Jorge. Instituto de Efectividad Clínica y Sanitaria; ArgentinaFil: Ciapponi, Agustín. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones en Epidemiología y Salud Pública. Instituto de Efectividad Clínica y Sanitaria. Centro de Investigaciones en Epidemiología y Salud Pública; Argentin

    Rapid Identification of Histoplasma capsulatum Directly from Cultures by Multiplex PCR

    Get PDF
    The multiplex PCR developed from a suspension of the yeast fungi correctly identified fifty-one clinical of H. capsulatum var. capsulatum strains isolated from clinical samples and soil specimens. The multiplex PCR was developed by combining two pairs of primers, one of them was specific to the H. capsulatum and the other one, universal for fungi, turned out to be specific to H. capsulatum, regardless of the fungus isolate studied. Primers designed to amplify a region of about 390-bp (Hc I-Hc II) and a region of approximately 600-bp (ITS1-ITS4) were used to identify a yeast isolated as H. capsulatum when both regions could be amplified. Absolute agreement (100 % sensitivity) could be shown between this assay and the cultures of H. capsulatum according to their morphological characteristics. Failure to amplify the target DNA sequence by PCR with primers Hc I-Hc II in the presence of the ITS1-ITS4 amplicon in isolates of P. brasiliensis, Cryptococcus neoformans, Trichosporon spp, Candida glabrata, C. albicans, C. tropicalis, C. parapsilosis, C. krusei, or Penicillium marneffei was an unequivocal sign of the high specificity of this assay. The assay specificity was also found to be 100 %. Incipient yeast forms obtained from clinical samples were identified as H. capsulatum by the PCR assay described before the morphological characteristics were registered shortening the time of diagnosis.Fil: Elías, Nahuel Alejandro. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Microbiología. Área Virología; ArgentinaFil: Cuestas, María Luján. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Microbiología. Área Virología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Sandoval, Macarena. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Microbiología. Área Virología; ArgentinaFil: Poblete, Gabriela. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Microbiología. Área Virología; ArgentinaFil: López Daneri, Gabriela. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Microbiología. Área Virología; ArgentinaFil: Jewtuchowicz, Virginia Marta. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Microbiología. Área Virología; ArgentinaFil: Iovannitti, Cristina. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Microbiología. Área Virología; ArgentinaFil: Mujica, María Teresa. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Microbiología. Área Virología; Argentin

    Carbon-encapsulated iron nanoparticles as reusable adsorbents for micropollutants removal from water

    Full text link
    Adsorption represents the most plausible technology for micropollutants removal from water nowadays. Nevertheless, the regeneration of the saturated carbon materials is still an important challenge, being these solids in practice commonly disposed. This work aims at overcoming this issue by using innovative carbonencapsulated iron nanoparticles (CE-nFe). This material was synthesized by a low-cost and green method viz. hydrothermal carbonization (HTC), using olive mill wastewater as carbonaceous source. The solid was fully characterized by different techniques (magnetic properties, elemental analyses, N2-sorption isotherms, pHPZC, ICP, XRD and TEM). It showed a clear core-shell structure of around 40 nm in diameter. The core was mainly formed by zero-valent iron and the shell by graphitized carbon. Accordingly, it showed an essentially mesoporous structure, with a specific surface area of 169 m2 g−1 , and a clear hydrophobic character (pHPZC = 10). Its adsorption performance was investigated using three relevant micropollutants (diclofenac (DCF), sulfamethoxazole (SMX) and metronidazole (MNZ)). A very fast removal of the micropollutants was achieved (30 min at the most, with rate constants in the range of 0.11–0.41 g mg−1 min−1 ). The adsorption isotherms revealed the vertical packing of the adsorbate molecules onto the adsorbent active centers, being the data successfully described by the GAB model. The saturated adsorbents were effectively regenerated by heterogeneous Fenton oxidation, taking advantage of the iron core of CE-nFe and the opened mesoporous carbon shell. The regeneration efficiency increased with increasing the operating temperature (25–75 ◦C) and contact time (1–4 h), as well as the H2O2 dose up to 6 g L-1. The micropollutant nature affected the adsorbent regeneration yield in the order: SMX > DCF > MNZ, consistent with their reactivity towards Fenton oxidationThis research has been supported by the Spanish MINECO through the project CTM-2016-76454-R and by the CM through the project P2018/EMT-4341. M. Munoz and J. Nieto-Sandoval thank the Spanish MINECO for the Ramón y Cajal postdoctoral contract (RYC-2016-20648) and the FPI predoctoral grant (BES-2017-081346), respectivel
    corecore