Assessment of carbon monoxide formation in Fenton oxidation process: The critical role of pollutant nature and operating conditions

This work assesses the carbon monoxide formation upon Fenton process, the most popular method for Advanced Oxidation Processes (AOPs). CO concentrations in the order of 11,000 mg/Nm3 were measured in the Fenton oxidation of phenol after 180 min reaction at 90 °C and 3 bar. The Fenton oxidation performed on phenol and its oxidized intermediates such as hydroquinone, catechol and short-chain acids allows concluding that CO is produced through the oxidative cleavage of aromatic rings; the hydroquinone route being more selective to CO than catechol. In all cases, the carbon mass balance was satisfactorily closed to 100%. The study of the influence of the operational conditions shows that CO production is clearly favoured at H2O2 dosage above the stoichiometric value and low temperatures (T< 90º). The H2O2 dosage was the most influence variable. The results of this work evidence for the first time the production of noxious amounts of CO along with CO2 in Fenton processes. This finding highlights the importance of evaluating not only liquid phase intermediates due to their recalcitrant and/or toxic behavior, but also gas phase because of CO emissions.Financial support from the project CTM2016-76454-R (Ministerio de Economia y Competitividad-MINECO, Spain) is gratefully acknowledge

Direct laser acceleration of electrons in free-space

Compact laser-driven accelerators are versatile and powerful tools of unarguable relevance on societal grounds for the diverse purposes of science, health, security, and technology because they bring enormous practicality to state-of-the-art achievements of conventional radio-frequency accelerators. Current benchmarking laser-based technologies rely on a medium to assist the light-matter interaction, which impose material limitations or strongly inhomogeneous fields. The advent of few cycle ultra-intense radially polarized lasers has materialized an extensively studied novel accelerator that adopts the simplest form of laser acceleration and is unique in requiring no medium to achieve strong longitudinal energy transfer directly from laser to particle. Here we present the first observation of direct longitudinal laser acceleration of non-relativistic electrons that undergo highly-directional multi-GeV/m accelerating gradients. This demonstration opens a new frontier for direct laser-driven particle acceleration capable of creating well collimated and relativistic attosecond electron bunches and x-ray pulses

Numerical analysis of the vibrational behavior of the moving assembly of a dynamic loudspeaker

En este trabajo se describe el proceso llevado a cabo para analizar numéricamente mediante el método de los elementos finitos (MEF) el comportamiento vibratorio del conjunto móvil de un altavoz dinámico de bobina con doble suspensión inferior y en ausencia de la superior. El estudio se centra en el rango de baja frecuencia. El calibrado del modelo se realiza en base a medidas experimentales de la frecuencia de resonancia y desplazamiento del diafragma. Se hace énfasis en la importancia de los factores de participación asociados a la fuerza de excitación y en los cambios que se producen en estos al introducir fuerzas no equilibradas. Así mismo, el análisis proporciona datos para decidir sobre la distancia entre suspensiones, su número óptimo de pliegues y la ubicación de las trencillas, siendo estos parámetros de gran interés en el diseño de este tipo de altavoces.This paper describes the process undertaken to analyze numerically the vibrational behavior of the moving assembly of a dynamic loudspeaker with double bottom suspension and in the absence of the above one using the finite element method (FEM). The study focuses on the low frequency range. Model calibration was performed based on experimental measurements of the resonance frequency and diaphragm displacement. The importance of the participation factors associated to the excitation force and the changes produced in these when unbalanced forces are introduced are emphasized. The analysis also provides data to decide on the distance between suspensions, their optimal number of folds and the placement of the lead wires, parameters of great interest on the design of this type of loudspeakers.Peer Reviewe

Inversion of the anomeric configuration of the transferred sugar during inactivation of the macrolide antibiotic oleandomycin catalyzed by a macrolide glycosyltransferase

AbstractMacrolides are a group of antibiotics structurally characterized by a macrocyclic lactone to which one or several deoxy-sugar moieties are attached. The sugar moieties are transferred to the different aglycones by glycosyltransferases (GTF). The OleI GTF of an oleandomycin producer, Streptomyces antibioticus, catalyzes the inactivation of this macrolide by glycosylation. The product of this reaction was isolated and its structure elucidated. The donor substrate of the reaction was UDP-α-D-glucose, but the reaction product showed a β-glycosidic linkage. The inversion of the anomeric configuration of the transferred sugar and other data about the kinetics of the reaction and primary structure analysis of several GTFs are compatible with a reaction mechanism involving a single nucleophilic substitution at the sugar anomeric carbon in the catalytic center of the enzyme

Modifications to the VV PHTS RELAP5 Model

Modifications and improvements to a previous RELAP5 model of the Vacuum Vessel Primary Heat Transfer System are described in this report. The modifications were new pump models, a new steam pressurizer, new coolant water control systems, additional pipe structures, and reduction of the pulse power to 6 MW

Pulse Sequences for NMR Quantum Computers: How to Manipulate Nuclear Spins While Freezing the Motion of Coupled Neighbours

We show how to divide a coupled multi-spin system into a small subset of ``active'' spins that evolve under chemical shift or scalar coupling operators, and a larger subset of ``spectator'' spins which are returned to their initial states, as if their motion had been temporarily frozen. This allows us to implement basic one-qubit and two-qubit operations from which general operations on $N$-qubits can be constructed, suitable for quantum computation. The principles are illustrated by experiments on the three coupled protons of 2,3-dibromopropanoic acid, but the method is applicable to any spin-1/2 nuclei and to systems containing arbitrary numbers of coupled spins.Comment: 11 pages, 5 fig

Understanding the active sites of boron nitride for CWPO: An experimental and computational approach

Hexagonal boron nitride (h-BN) has been explored as a catalyst for degrading persistent organic pollutants in wastewater by Catalytic Wet Peroxide Oxidation (CWPO). Herein, the superior activity of the h-BN on the phenol degradation (model pollutant) compared to other metal-free catalysts, such as carbon-based ones, and the lower selectivity to CO encourage the potential application of h-BN catalysts in CWPO processes. Through a combined density functional theory calculations, experimental reactions and catalyst characterization approach, a com- prehensive study on the reaction mechanism has been conducted. According to this, only defected B atoms in the h-BN layer, protonated as B-(OH2)+, decompose the hydrogen peroxide into highly reactive hydroxyl radicals. The radical species diffuse towards inner h-BN regions and react with the phenol adsorbed by π-π interaction on the h-BN surface. Oxidation by-products cause carbonaceous deposits and progressive deactivation of the h-BN catalyst that can be directly regenerated by burning off in air.Comunidad de Madrid-S2018/EMT-4341Ministerio de Ciencia e Innovación y Agencia Estatal de Investigación de España, y fondos FEDER de la Unión Europea (MCIU/AEI/FEDER, UE)-RTI2018-095052-B-I00Ministerio de Ciencia e Innovación de España y EU-FEDER-PID2019-106871 GB-I00Junta de Andalucía-FEDER-US-1381410Comunidad de Madrid-PEJD-2018-PRE/AMB-901

Arrendamiento, "aestimatio" y compraventa en Gayo, III, 146

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Derecho, Departamento de Derecho Romano, leída en 1978.Depto. de Derecho Romano e Historia del DerechoFac. de DerechoTRUEProQuestpu

Nitrofluorene derivatives trapped within MWCNTs for electrocatalysis of NADH: Substituent effects on π-π stacking interaction strength

We describe nanostructured electrode platforms composed of multiwalled carbon nanotube/glassy carbon electrodes (MWCNT/GCEs) with entrapped nitroaromatic compounds such as 2-nitrofluorene (2-NF), 2-nitro-9- fluorenone (2-NFN), 2,7-dinitrofluorene (2,7-NF) and 2,7-dinitro-9-fluorenone (2,7-NFN). All of the above ni- troaromatic compounds were tested as precursors for the production of redox mediator couples useful for NADH electrocatalysis. In this communication, we reveal the effect of the substituents on both the π-π stacking interaction strength and the electrocatalysis of NADH. The results show that the nitro group plays a triple role: it acts as a precursor of the mediator redox couple for NADH electrocatalysis; it increases the π-π stacking interaction with the electrode; and it acts as an electron acceptor substituent that promotes the electrocatalysis of NADHWe thank FONDECYT Grant 1170054 and 1210899 for financial supportDepartamento de Ingeniería Química, Química Física y Ciencias de los Materiale