Direct Hydroxylation of Phenol to Dihydroxybenzenes by H2O2 and Fe-based Metal-Organic Framework Catalyst at Room Temperature

A semi-crystalline iron-based metal-organic framework (MOF), in particular Fe-BTC, that contained 20 wt.% Fe, was sustainably synthesized at room temperature and extensively characterized. Fe-BTC nanopowders could be used as an efficient heterogeneous catalyst for the synthesis of dihydroxybenzenes (DHBZ), from phenol with hydrogen peroxide (H2O2), as oxidant under organic solvent-free conditions. The influence of the reaction temperature, H2O2 concentration and catalyst dose were studied in the hydroxylation performance of phenol and MOF stability. Fe-BTC was active and stable (with negligible Fe leaching) at room conditions. By using intermittent dosing of H2O2, the catalytic performance resulted in a high DHBZ selectivity (65%) and yield (35%), higher than those obtained for other Fe-based MOFs that typically require reaction temperatures above 70◦C. The long-term experiments in a fixed-bed flow reactor demonstrated good Fe-BTC durability at the above conditionsThe authors thank the financial support by Consejo Nacional de Ciencia y Tecnología (CONACYT) for the grant number 764635 and the project 256296; and to TNM for the supporting project 5627.19.P. Also, to the Spanish Ministerio de Ciencia, Innovación y Universidades (MICINN) and FEDER program (EU) through the projects: CTM2016-76454-R (MICINN) and RTI2018-095052-B-I00 ((MCIU/AEI/FEDER, UE

Structured reactors based on 3D Fe/SiC Catalysts: understanding the effects of mixing

The application of structured reactors provides a number of advantages in chemical processes. In this paper, two different three-dimensional (3D) Fe/SiC catalysts with a square cell geometry have been manufactured by Robocasting: monoliths (D = 14 and H = 15 mm) and meshes (D = 24 and H = 2 mm) and studied in the catalytic phenol oxidation by hydrogen peroxide (H2O2) for the sustainable production of dihydroxybenzenes (DHBZ). The fluid dynamics, catalytic performance, reaction rates, external mass transport limitation, and catalyst stability have been compared in three different reactors, monolithic fixed-bed reactor, multimesh fixed-bed reactor, and monolithic stirrer reactor, at selected operating conditions. The results show that the mechanical stirring of the 3D Fe/SiC monoliths avoids the external mass transfer limitation caused by the presence of oxygen bubbles in the channels (produced from the HOx· species in autoscavenging radical reactions). In addition, the backmixing has a positive effect on the efficient consumption of H2O2 but an adverse effect on the phenol selectivity to DHBZ since they are overoxidized to tar products at longer contact times. On the other hand, the wall porosity, and not the backmixing, affects the susceptibility of the 3D Fe/SiC catalyst to the Fe leaching, as occurs in the mesh structures. In conclusion, the monoliths operating under plug-flow and external mass transfer limitation in the monolithic fixed-bed reactor (MFB) provide an outstanding phenol selectivity to DHBZ and catalyst stabilityThis work is supported by the following agencies and grants: the Spanish Government under projects RTI2018-095052-BI00 (MICINN/AEI/FEDER, UE) and EIN2020-112153 (MCINN/AEI/10.13039/501100011033), the latter was also supported by the European Union through “NextGenerationEU/PRTR”, Community of Madrid under project S2018/ EMT-4341, and CSIC project I-COOP+ 2019 (ref COOPB20405). P.L. acknowledges the Community of Madrid and the European Social Fund for the financial support received through the contract PEJ-2019-AI/IND-14385. The authors thank Juliana Mejía for her technical assistanc

Detection of Replay Attacks to GNSS based on Partial Correlations and Authentication Data Unpredictability

Intentional interference, and in particular GNSS spoofing, is currently one of the most significant concerns of the Positioning, Navigation and Timing (PNT) community. With the adoption of Open Service Navigation Message Authentication (OSNMA) in Galileo, the E1B signal component will continuously broadcast unpredictable cryptographic data. This allows GNSS receivers not only to ensure the authenticity of data origin but also to detect replay spoofing attacks for receivers already tracking real signals with relatively good visibility conditions. Since the spoofer needs to estimate the unpredictable bits introduced by OSNMA with almost zero delay in order to perform a Security Code Estimation and Replay (SCER) attack, the spoofer unavoidably introduces a slight distortion into the signal, which can be the basis of a spoofing detector. In this work, we propose five detectors based on partial correlations of GNSS signals obtained over predictable and unpredictable parts of the signals. We evaluate them in a wide set of test cases, including different types of receiver and spoofing conditions. The results show that one of the detectors is consistently superior to the others, and it is able to detect SCER attacks with a high probability even in favorable conditions for the spoofer. Finally, we discuss some practical considerations for implementing the proposed detector in receivers, in particular when the Galileo OSNMA message structure is used

Entropy production and fluctuation theorems for monitored quantum systems under imperfect detection

The thermodynamic behavior of Markovian open quantum systems can be described at the level of fluctuations by using continuous monitoring approaches. However, practical applications require assessing imperfect detection schemes, where the definition of main thermodynamic quantities becomes subtle and universal fluctuation relations are unknown. Here we fill this gap by deriving a universal fluctuation relation that links entropy production in ideal and in inefficient monitoring setups. This provides a suitable estimator of dissipation using imperfect detection records that lower bounds the underlying entropy production at the level of single trajectories. We illustrate our findings with a driven-dissipative two-level system following quantum jump trajectories.Comment: 5 + 10 pages, 2 figures. The two first authors contributed equally to this wor

Trusting/distrusting auditors' opinion

Trust relations are essential for effective interchanges in the financial markets. Investors 9 (trustors), as well as other market participants, can only trust financial markets if they trust their 10 auditors (trustees). Especially, auditors' assessment on the client's financial condition and its 11 ability to continue as a going concern is paramount to improving social capital and maintaining 12 sustainable financial markets. Research shows that a going concern opinion may have immediate 13 consequences for both the auditing profession and financial statement users. We utilize the 14 Throughput Model to illustrate how different trust positions are aligned with a particular 15 auditor's decision-making pathway to enhance trust, distrust or no trust from the point of view of 16 investors' and creditors'

Enhanced fluid dynamics in 3D monolithic reactors to improve the chemical performance: experimental and numerical investigation

Three-dimensional (3D) Fe/SiC monoliths with parallel interconnected channels and different cell geometries (square, troncoconical, and triangular) were manufactured by robocasting and used as catalytic reactors in hydroxylation of phenol using hydrogen peroxide to produce dihydroxybenzenes; the reaction was performed at Cphenol,0 = 0.33 M, Cphenol,0:CH2O2,0 = 1:1 M, WR = 3.7 g, T = 80-90 °C, and τ = 0-254 gcat·h·L-1 with water as a solvent. The values of the apparent kinetic rate constants demonstrated the superior performance of the triangular cell monoliths for hydrogen peroxide decomposition, phenol hydroxylation, and dihydroxybenzene production reactions. A computational fluid dynamic model was validated with the experimental results. It demonstrated that the triangular cell monoliths, with a lower channel hydraulic diameter and not-facing interconnections, provided a higher internal macrotortuosity that induced an oscillating flow of the liquid phase inside the channels, leading to an additional transverse flow between adjacent parallel channels. This behavior, not observed in the other two geometries, resulted in a better overall performanceThe authors thank the financial support by the Community of Madrid through the project S2018/EMT-4341 and the Government of Spain through the projects: PGC2018- 095642-B-I00 and RTI2018-095052-B-I00 (MCIU/AEI/ FEDER, UE). Also, G. Vega acknowledges the Universidad Autónoma de Madrid for the predoctoral contrac

Improving distribution system state estimation with synthetic measurements

Distribution state estimation is a desired feature of modern power systems. The availability of measurements from smart meters has opened the door to extend the application of state estimation techniques down to end customers, preferably at the secondary distribution transformer level. However, the light coupling between phases makes the estimation of certain state variables, such as voltage phase angles, a great challenge. This paper proposes the use of synthetic measurements as a means of including cross-coupled information in the available set of measurements. This possibility can be easily implemented in line supervisors located at secondary transformer stations without the need for new hardware, just by embracing a different connection of measurement devices. This work demonstrates that this costless action results in a strong reduction of the sensibility of phase angle estimation errors with respect to measurement noise, thus leading to an important improvement in the quality of the results.publishedVersio

Identificacion de las mejores practicas de una organización de desarrollo software mediante la gestión de su conocimiento

En este artículo se describe un método para la identificación de las mejores prácticas de una organización de desarrollo de software, enfocándose en la disminución de la resistencia al cambio, a través de la gestión de su conocimiento. La importancia de la identificación de las mejores prácticas de una organización radica en que esta actividad permite conocer cómo trabaja una organización mediante la formalización, conservación y promoción de su conocimiento clave, lo cual, permitirá que las iniciativas de mejora de los procesos de la organización sean llevadas a cabo con éxito

Relationship between electrocardiographic characteristics of left bundle branch block and echocardiographic findings

Background: Complete left bundle branch block (CLBBB) is an electrocardiographic (ECG) dromotropic disorder seen in patients with various structural heart diseases and sometimes is associated with poor prognosis. Its presence confounds the application of standard ECG criteria for the diagnosis of left ventricular hypertrophy (LVH), myocardial infarction (MI) in the chronic phase, and pathologies that produce changes on ST-T segment. The aim of this investigation was to establish the relationship between CLBBB and cardiac structural abnormalities assessed by echocardiography. Methods: This observational, cross-sectional study included ECG with CLBBB from 101 patients who also had transthoracic echocardiogram (TTE) performed within 6 months. Results: The prevalence of structural heart disease on TTE was 90%. No ECG criterion was useful to diagnose LVH since no relationship was observed between 9 different ECG signs and increased left ventricular mass index. QRS duration (p = 0.16) and left axis deviation (p = 0.09) were unrelated to reduced left ventricular ejection fraction (LVEF). Eight ECG signs proposed for the diagnosis of the chronic phase of MI demonstrated similar effectiveness, with high specificity and reduced sensitivity. Conclusions: CLBBB is associated with elevated prevalence of cardiac structural disease and hinders the application of common ECG criteria for the diagnosis of LVH, reduced LVEF, or chronic phase of MI. No ECG finding distinguished patients with structural heart disease from those with normal hearts. Electrocardiographic criteria for the diagnosis of MI in the chronic phase are useful when present, but when absent cannot rule it out.