Formation of polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs) in the electrochemical oxidation of polluted waters with pharmaceuticals used against COVID-19

The COVID-19 pandemic has produced a huge impact on our lives, increasing the consumption of certain pharmaceuticals, and with this, contributing to the intensification of their presence in wastewater and in the environment. This situation demands the implementation of efficient remediation technologies, among them, electrochemical oxidation (ELOX) is one the most applied. This work studies the application of ELOX with the aim of eliminate pharmaceuticals used in the fight against COVID-19, assessing its degradation rate, as well as the risk of formation of toxic trace by-products, such as unintentional POPs like polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). To this end, model solutions containing 10 mg L-1 of dexamethasone (DEX), paracetamol (PAR), amoxicillin (AMX), and sertraline (STR) with two different electrolytes (NaCl and Na2SO4) have been evaluated. However, electrochemical systems that contain chloride ions in solution together with PCDD/Fs precursor molecules may lead to the formation of these highly toxic by-products. So, PCDD/Fs were quantified under conditions of complete degradation of the drugs. Furthermore, the presence of PCDD/Fs precursors such as chlorophenols was determined, as well as the role of Cl-, Cl- and radicals in the formation of the by-products and PCDD/Fs. The maximum measured concentration of PCDD/Fs was around 2700-pg-L-1 for the amoxicillin case in NaCl medium. The obtained results emphasise the importance of not underestimating the potential formation of these highly toxic trace by-products, in addition to the correct selection of oxidation processes and operation variables, in order to avoid final higher toxicity in the medium.This research was developed in the framework of the project PID2020–115409RB-I00 (MCIN/AEI) financed by the Spanish Ministry of Science and Innovation. Sophie Schroder is also grateful to MCIN for the FPI grant PRE2018–83526

Photocatalytic transformation of triclosan. Reaction products and kinetics

5-Chloro-2-[2,4-dichlorophenoxy]-phenol, or triclosan (TCS), is an antimicrobial and antifungal agent with high resistance to conventional wastewater treatments, thus, more effective remediation technologies are necessary, where photocatalytic processes deserve special attention due to the high degradation rates of TCS, and the use of a renewable source of energy. However, different by-products may be formed during the treatment, sometimes more harmful than the parent compounds. Efforts to detail reaction pathways continually feed into related literature; however, knowing the transformation kinetics and the dependence on the operating variables is essential for the correct design of the abovementioned remediation technologies. This work contributes to increasing the knowledge necessary for the application of photocatalytic processes for the degradation of emerging pollutants, with TCS as a case study. First, an experimental plan to analyze the influence of the operating variables was carried out, determining time courses of the parent and intermediate compounds. Next, the kinetic model and parameters that are capable of predicting TCS concentration and its derivatives as a function of the operating conditions are provided. This constitutes a very useful tool to predict the performance of wastewater remediation treatment both in the degradation of the original pollutant and in the reduction of the toxicity in the treated water.This research was funded by the Spanish Ministry of Economy and Competitiveness (MINECO) (CTM2017-87740-R and RTI2018-093310-B-I00)

Causalidad probabilística en las acciones medicas como sustento de la jurisprudencia democrática

Se considera la democracia como amplia serie de relaciones basadas en la vigencia de los derechos humanos. En consecuencia, supeditar las acciones médicas a la dignidad que contiene la vida, significa promover encuentros plurales y justos. En tanto, la investigación tiene el propósito de analizar la causalidad probabilística como sustento de la jurisprudencia democrática, con estudios de caso donde se consideran eventos fácticos con la finalidad de impulsar las reflexiones que justifican los hallazgos y las discusiones. Concluye que las acciones jurídicas al vigilar y controlar las prácticas de salud, al atender los límites de la causalidad probabilística, benefician la manifestación de coexistencias habitables al ser equitativas frente a la coyuntura actual de salud y la aparición de nuevos tipos de daños donde muchas veces la difícil prueba de la relación causal lleva a que se frustren las demandas, pues, en muchos casos, ni siquiera se puede recurrir a la regla de la causalidad adecuada.Campus Lima Nort

Potential formation of PCDD/Fs in triclosan wastewater treatment: an overall toxicity assessment under a life cycle approach

Wastewater may contain a diverse group of unregulated pollutants known as emerging pollutants, such as pharmaceuticals and personal care products (PPCPs). Triclosan (TCS) is a personal care product widely used as an antiseptic or preservative in cosmetics, hand wash, toothpaste and deodorant soaps. Advanced oxidation processes (AOPs) have been used as effective and alternative treatments for complex wastewater. However, an important criterion for the assessment of AOPs and their operation conditions could be the potential formation of new toxic secondary products, such as polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), especially when emerging pollutants are present in the media. If these are omitted from environmental management studies, the real environmental impacts of a WWTPs (wastewater treatment plants) may be underestimated. Consequently, the current study aims to evaluate the environmental impacts derived from electrooxidation (EOX), one of the most effective oxidation technologies, of emerging pollutants using Life Cycle Assessment. The analyses were performed for the treatment of effluents containing TCS, firstly without considering the formation of PCDD/Fs and, thereafter, considering the effects of these compounds. Total toxicity, calculated through different methods and corresponding impact factors, were evaluated for each stage of the process when different electrolytes are used, including PCDD/Fs formation. Finally, a sensitivity analysis was carried out to study i) the effect of the TCS initial concentration on the environmental impacts associated to ecotoxicity for the different life cycle methods and ii) the influence of changing the organic pollutant on PCDD/Fs formation employing 2-chlorophenol (2-CP). As a result, LCIA methods demonstrate that they are not fully adapted to the computation of PCDD/Fs in the water compartment, since only 2,3,7,8-tetraclorodibenzo-p-dioxina (2,3,7,8-TCDD) is present as a substance in the impact categories assessed, ignoring the remaining list of PCDD/Fs.This research was developed in the framework of the project CTM2017-87740-R and CTM2016-76176-C2-1-R financed by the Spanish Ministry of Economy and Competitiveness (MINECO). Claudia Solá-Gutiérrez and Sophie Schröder are also grateful for its correspondent FPI grant BES-2015-072920 and PRE2018-083526, respectively. Ian Vázquez-Rowe wishes to thank the Dirección General de Investigación (DGI), Project N°636, and the Dirección Académica de Relaciones Internacionales (DARI) from the Pontificia Universidad Católica del Perú (PUCP) for financial support during his stay at the Universidad de Cantabria (Spain)

Weibull strength distribution and reliability S-N percentiles for tensile tests

Based on the true stress, the ultimate material’s strength, and the fatigue slope b values, the probabilistic percentiles of the S-N curve of ductile materials are formulated. The Weibull β and η parameters used to determine the product’s reliability are determined directly from the material’s strength values corresponding to 103 and 106 cycles. And since in Table corresponding to the properties of this A538 A (b) steel and collected by table 23-A of Shigley Mechanical Engineering Design book; authors present the σt, Sut, and b values of several materials, then the Weibull parameters for each one of these materials as well as the 95% and 5% reliability percentiles of their S-N curves are given. A step-by-step application to the steel A538 A (b) material is presented. And based on the maximum and minimum applied stress values, the corresponding Weibull stress distribution was fitted and used with the Weibull strength distribution, in the stress/strength reliability function to determine the element’s reliability

Fatigue-Life Prediction of Mechanical Element by Using the Weibull Distribution

Applying Goodman, Gerber, Soderberg and Elliptical failure theories does not make it possible to determine the span of failure times (cycles to failure-Ni) of a mechanical element, and so in this paper a fatigue-life/Weibull method to predict the span of the Ni values is formulated. The input’s method are: (1) the equivalent stress ( eq) value given by the used failure theory; (2) the expected Neq value determined by the Basquin equation; and (3) theWeibull shape and scale parameters that are fitted directly from the applied principal stress 1 and 2 values. The e ciency of the proposed method is based on the following facts: (1) the and parameters completely reproduce the applied 1 and 2 values. (2) The method allows us to determine the reliability index R(t), that corresponds to any applied 1i value or observed Ni value. (3) The method can be applied to any mechanical element’s analysis where the corresponding 1 and 2, eq and Neq values are known. In the performed application, the 1 and 2 values were determined by finite element analysis (FEA) and from the static stress analysis. Results of both approaches are compared. The steps to determine the expected Ni values by using theWeibull distribution are given

Método Weibull para la Reducción de Tiempo de Prueba Ambiental para Divisor Óptico

En este artículo se desarrolla un plan de prueba de vida para un divisor óptico estándar, que permite conocer su tiempo de vida útil y su confiabilidad R(t). De acuerdo con el estándar GR-2866, las variables ambientales a analizar son temperatura (T) y humedad (H) y se deben de correr 12 muestras. Durante el análisis, 720 ciclos de T y H fueron realizados durante un periodo de prueba de 30 días (Temp. = 85°, -40° y Hum. = 85%). Así, con la finalidad de reducir el tiempo de prueba, haciendo uso del método Taguchi, el rango de temperatura más significante fue determinado. Con este nuevo rango de temperatura de prueba (T = 100°, -45° y H = 85%) en el modelo de CoffinManson, el nuevo tiempo de prueba fue de 10.33 días. Las pruebas experimentales se realizaron mediante el uso de una cámara ambiental y equipo óptico que permitió medir la cantidad de atenuación en decibeles (dB) causada por el estrés de la temperatura y humedad. Para este nuevo rango de prueba los parámetros Weibull son β = 3.19 y η = 92.4

Weibull S-N Fatigue Strength Curve Analysis for A572 Gr. 50 Steel, Based on the True Stress—True Strain Approach

In this paper a Weibull methodology to determine the probabilistic percentiles for the S-N curve of the A572 Gr. 50 steel is formulated. The given Weibull/S-N formulation is based on the true stress and true strain values, which are both determined from the stress-strain analysis. For the analysis, theWeibull and parameters are both determined directly from the maximum and minimum addressed stresses values. The S-N curve parameters are determined for 103 and 106 cycles. In the application, published experimental data for the CSA G40.21 Gr. 350W steel is used to derive the true stress and true strain parameters of the A572 Gr. 50 steel. Additionally, the application of the S-N curve, its probabilistic percentiles and theWeibull parameters that represent these percentiles are all determined step by step. Since the proposed method is flexible, then it can be applied to determine the probabilistic percentiles of any other material

Método Weibull para la reducción de tiempo de prueba ambiental para divisor óptico

This article develops a life test plan for a standard optical splitter, which provides insight into its lifetime and reliability R (t). According to the GR-2866 standard, the environmental variables to be analyzed are temperature (T) and humidity (H) and 12 samples must be run. During the analysis, 720 cycles of T and H were performed during a 30-day trial period (Temp. = 85 °, -40 ° and Hum. = 85%). Thus, in order to reduce the test time, using the Taguchi method, the most significant temperature range was determined. With this new test temperature range (T = 100 °, -45 ° and H = 85%) in the Coffin-Manson model, the new test time was 10.33 days. The experimental tests were carried out using an environmental camera and optical equipment that allowed measuring the amount of attenuation in decibels (dB) caused by stress from temperature and humidity. For this new test range the Weibull parameters are β = 3.19 and η = 92.47.En este artículo se desarrolla un plan de prueba de vida para un divisor óptico estándar, que permite conocer su tiempo de vida útil y su confiabilidad R(t). De acuerdo con el estándar GR-2866, las variables ambientales a analizar son temperatura (T) y humedad (H) y se deben de correr 12 muestras. Durante el análisis, 720 ciclos de T y H fueron realizados durante un periodo de prueba de 30 días (Temp. = 85°, -40° y Hum. = 85%). Así, con la finalidad de reducir el tiempo de prueba, haciendo uso del método Taguchi, el rango de temperatura más significante fue determinado. Con este nuevo rango de temperatura de prueba (T = 100°, -45° y H = 85%) en el modelo de Coffin-Manson, el nuevo tiempo de prueba fue de 10.33 días.  Las pruebas experimentales se realizaron mediante el uso de una cámara ambiental y equipo óptico que permitió medir la cantidad de atenuación en decibeles (dB) causada por el estrés de la temperatura y humedad. Para este nuevo rango de prueba los parámetros Weibull son β = 3.19 y η = 92.47