CFD simulation of multiple dust explosion occurred in a flour mill

Dust explosions pose a serious hazard to both personnel and equipment in industries that handles combustible powders. Although prevention and mitigation technology of dust explosions has progressed greatly, continual accidents in the process industries demonstrate the need for improved knowledge in this area (Mercan, 2016; Russo et al., 2017). On July 16, 2007, a primary explosion followed by secondary explosions happened in the Cordero mill (Italy) and 5 persons died (Marmo et al., 2012). The accident occurred at the end of the loading operation of a tanker, when a surplus of flour was overcharged. This extra amount was then pneumatically conveyed to a silo placed in the flour-warehouses, by connecting the tanker to the pneumatic transport line through one of the tanker hoses. The flour was loaded at a low flow rate, and hence a low concentration of flour in the duct occurred. The source of ignition of the dust cloud was attributed to an electrostatic arc that took place in the pneumatic transport duct (Marmo et al., 2012). The technical enquire found signs of the explosion in the duct: internal pressure provoked evident deformation of the duct. As widely discussed in the literature (Fiorentini and Marmo 2019; Marmo et al., 2013), Computational Fluid Dynamics can be a valid aid to forensic engineering because it allows to discern the incidental sequence that is more adherent to the evidence. The aim of this work is to reproduce the conditions present in the mill at the time of the accident using the CFD-code DESC, which is being developed for simulating dust explosions in complex geometries. The results obtained from the simulations were compared to the damage observed after the accident in order to identify the more credible scenario. Simulations with different levels of flour in the silo, concentration of dust in the air mixture and position of ignition were performed. Analysis of results revealed the effect of different parameters on the severity of dust explosion, not only limited to the case study investigated, in order to adopt the appropriate prevention and protection measures

Distribution of Relaxation Times Based on Lasso Regression: A Tool for High-Resolution Analysis of IMPS Data in Photoelectrochemical Systems

Intensity-modulated photocurrent spectroscopy (IMPS) has been largely employed in semiconductor characterization for solar energy conversion devices to probe the operando behavior with widely available facilities. However, the implementation of IMPS data analysis to complex structures, whether based on the physical rate constant model (RCM) or the assumption-free distribution of relaxation times (DRT), is generally limited to a semi-quantitative description of the charge carrier kinetics of the system. In this study, a new algorithm for the analysis of IMPS data is developed, providing unprecedented time resolution to the investigation of μs to s charge carrier dynamics in semiconductor-based systems used in photoelectrochemistry and photovoltaics. The algorithm, based on the previously developed DRT analysis, is herein modified with a Lasso regression method and available to the reader free of charge. A validation of this new algorithm is performed on a α-Fe2O3 photoanode for photoelectrochemical water splitting, identified as a standard platform in the field, highlighting multiple potential-dependent charge transfer paths, otherwise hidden in the conventional IMPS data analysis

Indium-modified copper nanocubes for syngas production by aqueous CO2 electroreduction

Electroreduction of carbon dioxide represents an appealing strategy to rethink a waste product as a valuable feedstock for the formation of value-added compounds. Among the metal electrodes able to catalyze such processes, copper plays a central role due to its rich chemistry. Strategies aimed at tuning Cu selectivity comprise nanostructuring and alloying/post-functionalization with heterometals. In this contribution, we report on straightforward electrochemical methods for the formation of nanostructured Cu-In interfaces. The latter were fully characterized and then used as cathodes for CO2 electroreduction in aqueous environment, leading to the selective production of syngas, whose composition varies upon changing the applied bias and indium content. In particular, gaseous mixtures compatible with the synthesis of methanol or aldehydes (i.e. respectively with 1 : 2 and 1 : 1 CO/H2 ratios) are produced at low (i.e. −0.62 V vs. RHE) applied bias with >3.5 mA cm−2 current densities (in absolute value). Even if the proposed cathodes undergo structural modifications upon prolonged exposure to CO2 reduction conditions, their catalytic activity can be restored by introducing an additional In(iii) precursor to the electrolytic solution

Measurement of Wall Shear Stress Exerted by Flowing Blood in the Human Carotid Artery: Ultrasound Doppler Velocimetry and Echo Particle Image Velocimetry

This is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordVascular endothelial cells lining the arteries are sensitive to wall shear stress (WSS) exerted by flowing blood. An important component of the pathophysiology of vascular diseases, WSS is commonly estimated by centerline ultrasound Doppler velocimetry (UDV). However, the accuracy of this method is uncertain. We have previously validated the use of a novel, ultrasound-based, particle image velocimetry technique (echo PIV) to compute 2-D velocity vector fields, which can easily be converted into WSS data. We compared WSS data derived from UDV and echo PIV in the common carotid artery of 27 healthy participants. Compared with echo PIV, time-averaged WSS was lower using UDV (28 ± 35%). Echo PIV revealed that this was due to considerable spatiotemporal variation in the flow velocity profile, contrary to the assumption that flow is steady and the velocity profile is parabolic throughout the cardiac cycle. The largest WSS underestimation by UDV was found during peak systole (118 ± 16%) and the smallest during mid-diastole (4.3± 46%). The UDV method underestimated WSS for the accelerating and decelerating systolic measurements (68 ± 30% and 24 ± 51%), whereas WSS was overestimated for end-diastolic measurements (−44 ± 55%). Our data indicate that UDV estimates of WSS provided limited and largely inaccurate information about WSS and that the complex spatiotemporal flow patterns do not fit well with traditional assumptions about blood flow in arteries. Echo PIV-derived WSS provides detailed information about this important but poorly understood stimulus that influences vascular endothelial pathophysiology.National Institute of HealthNational Institute for Health Research (NIHR

Photoelectrochemical Valorization of Biomass Derivatives with Hematite Photoanodes Modified by Cocatalysts

The solar-driven oxidation of biomass to valuable chemicals is rising as a promising anodic reaction in photoelectrochemical cells, replacing the sluggish oxygen evolution reaction and improving the added value of the energy conversion process. Herein, the photooxidation of 5-hydroxymethylfurfural into furan dicarboxylic acid (FDCA) is performed in basic aqueous environment (borate buffer, pH 9.2), with the addition of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) as redox mediator. Because of its good stability, cost-effectiveness, and nontoxicity, titanium-modified hematite (Ti:Fe2O3) photoanodes are investigated to this aim, and their performance is tuned by engineering the semiconductor surface with a thin layer of Co-based cocatalysts, i.e., cobalt iron oxide (CoFeO x ) and cobalt phosphate (CoPi). Interestingly, the electrode modified with CoPi shows improved efficiency and selectivity toward the final product FDCA The source of this enhancement is correlated to the effect of the cocatalyst on the charge carrier dynamics, which is investigated by electrochemical impedance spectroscopy and intensity-modulated photocurrent spectroscopy analysis. In addition, the results of the latter are interpreted through a novel approach called Lasso distribution of relaxation time, revealing that CoPi cocatalyst is effective in the suppression of the recombination processes and in the enhancement of direct hole transfer to TEMPO

Hepatitis B virus-infection related cryoglobulinemic vasculitis. Clinical manifestations and the effect of antiviral therapy: A review of the literature

Objective: Hepatitis B virus (HBV) infection causes chronic hepatitis, cirrhosis, and hepatocellular carcinoma. Furthermore, about 20% of the patients develop extrahepatic manifestations such as cryoglobulinemic vasculitis (CV), polyarteritis nodosa, non-rheumatoid arthritis, glomerulonephritis and non-Hodgkin lymphoma. This review analyzed literature data on clinical manifestations of HBV-related CV and the impact of antiviral therapy with analoques nucleotide. Methods: A PubMed search was performed to select eligible studies in the literature, up to July 2022. Results: Some studies have analyzed clinical manifestations in HBV-related CV and have investigated the role of antiviral therapy with nucleotides analogues (NAs). Clinical manifestations of CV vary from mild to moderate (purpura, asthenia and arthralgias) to severe (leg ulcers, peripheral neuropathy, glomerulonephritis, and non-Hodking lymphoma). NAs therapy leads to suppression of HBV-DNA; therefore, it is capable of producing clinical response in the majority of patients with mild to moderate symptoms. Conclusion: Antiviral therapy with NAs is the first choice for HBV suppression and control of mild to moderate disease. In severe vasculitis (glomerulonephritis, progressive peripheral neuropathy and leg ulcers), rituximab alone or with plasma-exchange is always indicated in combination with antiviral therapy

Hepatitis C virus and non-Hodgkin's lymphomas: Meta-analysis of epidemiology data and therapy options.

Hepatitis C virus (HCV) is a global health problem affecting a large fraction of the world\u2019s population: This virus is able to determine both hepatic and extrahepatic diseases. Mixed cryoglobulinemia, a B-cell \u201cbenign\u201d lymphoproliferative disorders, represents the most closely related as well as the most investigated HCV-related extrahepatic disorder. Since this virus is able to determine extrahepatic [non-Hodgkin\u2019s lymphoma (NHL)] as well as hepatic malignancies (hepatocellular carcinoma), HCV has been included among human cancer viruses. The most common histological types of HCV-associated NHL are the marginal zone, the lymphoplasmacytic and diffuse large cell lymphomas. The role of the HCV in the pathogenesis of the B-cell lymphoproliferative disorders is confirmed also by the responsiveness of the NHL to antiviral therapy. The purpose of this review is to provide an overview of the recent literature and a meta analysis of the epidemiology data, to explain the role of HCV in the development of NHL\u2019s lymphoma. Furthermore, the possibility to treat these HCV-related NHL with the antiviral therapy or with other therapeutic options, like chemotherapy, is also discussed

Photophysical and structural characterisation of in situ formed quantum dots

Conjugated polymer–semiconductor quantum dot (QD) composites are attracting increasing attention due to the complementary properties of the two classes of materials. We report a convenient method for in situ formation of QDs, and explore the conditions required for light emission of nanocomposite blends. In particular we explore the properties of nanocomposites of the blue emitting polymer poly[9,9-bis(3,5-di-tert-butylphenyl)-9H-fluorene] together with cadmium sulphide (CdS) and cadmium selenide (CdSe) precursors. We show the formation of emissive quantum dots of CdSe from thermally decomposed precursor. The dots are formed inside the polymer matrix and have a photoluminescence quantum yield of 7.5%. Our results show the importance of appropriate energy level alignment, and are relevant to the application of organic–inorganic systems in optoelectronic devices