Comparison of Thermocline Molten Salt Storage Performances to Commercial Two-tank Configuration☆

Abstract This work deals with the assessment of thermocline heat storage performances when applied to solar thermal plants. The considered thermocline is based on molten salt heat transfer fluid (Solar Salts between 300 °C and 550 °C) and filled with quartzite. A 2-D finite element heat transfer model is developed to determine the temperatures inside the vessel with mass flows input/output. The model includes heat conductivity of molten salt and quartzite rocks, heat transfer between the molten salts and the quartzite, as well as heat loss to the environment. Results of the model are compared to available experimental data as well as analytic results showing good agreement. Then, the thermocline storage with the performances predicted by the 2-D code was integrated in a CSP plant previously modelled with the two-tank TES system. Plant management is kept equal to the two-tank configuration. A performance index is introduced to make a consistent comparison between the thermocline and the two-tank system: storage efficiency is defined as the heat withdrawn from the storage above 545 °C divided by the overall input in the storage. The defined index is equal to 100% for the two tank system as thermal losses have a negligible impact. On the contrary, in thermocline storage, part of heat stored in the molten salt is in the thermocline region and this molten salt is not accounted as useful. The thickness of the thermocline is about 4 to 6 meter height out of 14 meters making the storage performances in the range of 65%, hence significantly lower than in two-tank configuration. A sensitivity analysis on tank size and tank shape factor is performed to assess the optimal configuration for the thermocline

Three-dimensional charge transport mapping by two-photon absorption edge transient-current technique in synthetic single-crystalline diamond

We demonstrate the application of two-photon absorption transient current technique to wide bandgap semiconductors. We utilize it to probe charge transport properties of single-crystal Chemical Vapor Deposition (scCVD) diamond. The charge carriers, inside the scCVD diamond sample, are excited by a femtosecond laser through simultaneous absorption of two photons. Due to the nature of two-photon absorption, the generation of charge carriers is confined in space (3-D) around the focal point of the laser. Such localized charge injection allows to probe the charge transport properties of the semiconductor bulk with a fine-grained 3-D resolution. Exploiting spatial confinement of the generated charge, the electrical field of the diamond bulk was mapped at different depths and compared to an X-ray diffraction topograph of the sample. Measurements utilizing this method provide a unique way of exploring spatial variations of charge transport properties in transparent wide-bandgap semiconductors.Comment: This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. The following article appeared in Applied Physics Letters and may be found at https://doi.org/10.1063/1.509085

Development of a CFD methodology for fuel-air mixing and combustion modeling of GDI Engines

Simulation of GDI engines represents a very challenging task for CFD modeling. In particular, many sub-models are involved since the evolution of the fuel spray and liquid film formation should be modeled. Furthermore, it is necessary to account for both the influence of mixture and flow conditions close to the spark plug to correctly predict the flame propagation process. In this work, the authors developed a CFD methodology to study the air-fuel mixing and combustion processes in direct-injection, spark-ignition engines. A set of sub-models was developed to describe injection, atomization, breakup and wall impingement for sprays emerging from multi-hole atomizers. Furthermore, the complete evolution of the liquid fuel film was described by solving its mass, energy and momentum equations on the cylinderw wall boundaries. To model combustion, the Extended Coherent Flamelet Model (ECFM) was used in combination with a Lagrangian ignition model, describing the evolution of the flame kernel and accounting for both for flow, mixture composition and properties of the electrical circuit. The proposed approach has been implemented into the Lib-ICE code, which is based on the OpenFOAMR technology. In this paper, examples of application are provided, including the simulation of the fuel-air mixing process in a real GDI engine and the prediction of the premixed turbulent combustion process in a constant-volume vessel for different operating conditions

LA TASA DE EGRESO DE QUIENES INGRESAN POR APLICACIÓN DEL ARTÍCULO 7º DE LA LEY DE EDUCACIÓN SUPERIOR Y SU RELACIÓN CON LA TASA DE QUIENES INGRESAN CON ESTUDIOS SECUNDARIOS COMPLETOS

Este trabajo es uno de los resultados del proyecto de investigación en que nos encontramos trabajando, que tiene por objeto estudiar el desempeño académico que tuvieron quienes ingresaron en la Universidad Nacional de Luján (UNLu) sin acreditar estudios de nivel medio completo, en el marco del artículo 7º de la Ley 24.521 (LES). Al mismo tiempo, nos proponemos comparar el desempeño académico observado en estos estudiantes con el de quienes ingresaron acreditando estudios completos. En esta oportunidad presentamos el resultado de analizar la tasa de egreso, calculada por cohorte, de los ingresantes mayores de 25 años que no acreditaron estudios completos de nivel medio, de las cohortes comprendidas entre los años 1996 y 2005, ambas inclusive. Por otra parte, se efectuó el mismo estudio para quienes ingresaron en esas cohortes pero habiendo acreditado estudios secundarios completos, con el objeto de comparar la tasa de egreso de las dos poblaciones. Los resultados alcanzados mostraron que, para las diez cohortes estudiadas la tasa media de egreso difiere en 3 puntos, a favor de quienes ingresaron con estudios de nivel medio completo. Por otra parte, para alguna de las cohortes la tasa es superior para quienes ingresaron sin acreditar estudios completos

Use of intensive rearing systems as back‐up for coastal lagoon aquaculture: an experience with eels, Anguilla anguilla L., in the Comacchio lagoons

. The possibility of using eels from intensive rearing ponds to restock natural basins has been investigated by comparing growth, survival and rate of yellow-to-silver metamorphosis of 'wild type' eels and of eels from an intensive rearing pond. A total of 2243 marked eels were released into a closed natural environment of 22ha; 1254 were wild type (average length 45·6 ± 9·0cm), and 989 from an intensive rearing pond, split by a mechanical grader in two groups. The first group was made of 617 well-growing eels (44·9 ± 3·0cm), the second one of 372 smaller eels (36·9 ± 4·3cm) which had not adapted to the artificial conditions. The starting size being equal the animals grew to the same extent; in some cases the animals previously adapted to the artificial pond grew better than the wild type. The rate of metamorphosis from yellow to silver eel was 28·4% for the wild type eels and 22% for the others, although the latter became mostly silver males. Survival of the wild type eels (starting with the 35-cm size class and covering the period from April to December) was calculated by mark-recapture at approximately 98·6%. For the eels previously well adapted to the intensive rearing pond it was only 85%, indicating some difficulty in competing in the natural environment. The good growth shown by the smaller eels, with a survival of about 90%, would seem to indicate that these animals might be effectively used for restocking purposes, thus favouring an integration between the intensive ponds and the extensive environments

Affinity labeling of the active center and ribonucleoside triphosphate binding site of yeast DNA primase.

Abstract A highly selective affinity labeling procedure has been applied to map the active center of DNA primase from the yeast Saccharomyces cerevisiae. Enzyme molecules that have been modified by covalent attachment of benzaldehyde derivatives of adenine nucleotides are autocatalytically labeled by incubation with a radioactive ribonucleoside triphosphate. The affinity labeling of primase requires a template DNA, is not affected by DNase and RNase treatments, but is sensitive to proteinase K. Both the p58 and p48 subunits of yeast DNA primase appear to participate in the formation of the catalytic site of the enzyme, although UV-photocross-linking with [alpha-32P]ATP locates the ribonucleoside triphosphate binding site exclusively on the p48 polypeptide. The fixation of the radioactive product has been carried out also after the enzymatic reaction. Under this condition the RNA primers synthesized by the DNA polymerase-primase complex under uncoupled DNA synthesis conditions are linked to both DNA primase and DNA polymerase. When DNA synthesis is allowed to proceed first, the labeled RNA chains are fixed exclusively to the DNA polymerase polypeptide. These results, in accord with previous data, have been used to propose a model illustrating the interactions and the putative roles of the polypeptides of the DNA polymerase-primase complex

Isolated Intraocular Relapse of Pediatric B-cell Precursor Acute Lymphoblastic Leukaemia Following Chimeric Antigen Receptor T-lymphocyte Therapy

Chimeric antigen receptor T-lymphocytes (CAR T) targeting the CD19 surface antigen have achieved a breakthrough in the treatment of multiply relapsed and refractory bone marrow (BM) disease in childhood B-cell precursor acute lymphoblastic leukaemia (B-ALL). The ability of CAR T therapy to treat extramedullary (EM) disease is less proven. However, early reports suggest trafficking of CART-cells to the central nervous system (CNS) as well as other EM sites. We describe a case of isolated intraocular relapse of pediatric B-ALL following CAR T-cell therapy, which had successfully controlled multiply relapsed BM and CNS disease. CAR T-cells may not be able to traffic into the eye, making it a "sanctuary" site during therapy

COVID-19 incidence and mortality in Lombardy, Italy: An ecological study on the role of air pollution, meteorological factors, demographic and socioeconomic variables

Lombardy, the most populated and industrialized Italian region, was the epicentre of the first wave (March and April 2020) of COVID-19 in Italy and it is among the most air polluted areas of Europe. We carried out an ecological study to assess the association between long-term exposure to particulate matter (PM) and nitrogen dioxide (NO2) on COVID-19 incidence and all-cause mortality after accounting for demographic, socioeconomic and meteorological variables. The study was based on publicly available data. Multivariable negative binomial mixed regression models were fitted, and results were reported in terms of incidence rate ratios (IRRs) and standardized mortality ratios (SMR). The effect of winter temperature and humidity was modelled through restricted cubic spline. Data from 1439 municipalities out of 1507 (95%) were included in the analyses, leading to a total of 61,377 COVID-19 cases and 40,401 deaths from all-causes collected from February 20th to April 16th and from March 1st to April 30th, 2020, respectively. Several demographic and socioeconomic variables resulted significantly associated with COVID-19 incidence and all-cause mortality in a multivariable fashion. An increase in average winter temperature was associated with a nonlinear decrease in COVID-19 incidence and all-cause mortality, while an opposite trend emerged for the absolute humidity. An increase of 10 μg/m3 in the mean annual concentrations of PM2.5 and PM10 over the previous years was associated with a 58% and 34% increase in COVID-19 incidence rate, respectively. Similarly, a 10 μg/m3 increase of annual mean PM2.5 concentration was associated with a 23% increase in all-cause mortality. An inverse association was found between NO2 levels and COVID-19 incidence and all-cause mortality. Our ecological study showed that exposure to PM was significantly associated with the COVID-19 incidence and excess mortality during the first wave of the outbreak in Lombardy, Italy