This paper presents an insight on the pedagogy and strategic design of the organization of the four experimental subjects of the Chemical Engineering Degree Curricula at the Universidad Politécnica ...de Madrid (GIQ-ETSII-UPM). Outcome-based learning is applied, focused on the student’s work, centering explicitly in Experimental Design outcomes. These skills are necessary not only for research, but also for innovation activities that will be fundamental for future engineers and chemists, and students should be encouraged to practice them during their time at university. The learnings are graduated following the requirements of the courses, and experimentations are realistic and easily approached as guided or free experimentation. Students must apply previous knowledge and acquire new ones, implement attitudes, work in teams, and make their own decisions. Among the students’ free comments collected in teacher surveys carried out on more than 400 students over 10 years, there are recurrent evaluations such as “We are able to put into practice what we have studied in other subjects”. These subjects are the ones students perceive as very important toward their future. Feedback is essential to improve their experimental proposals and make them viable to avoid student frustration. The number of teachers involved is between a minimum of 3 and a maximum of 7 for 30–40 students and 14 sessions in each subject. It is essential to note that the teacher’s engagement is indispensable for the performance of this framework.
The boron adsorption process, in borate ion form, onto magnesium oxide was described in terms of mathematical equations and, taking into account the knowledge acquired by means of experimental data, ...the most probable mechanism of boron removal process was proposed. The modelization has been carried out by establishing Langmuir adsorption isotherms and kinetic law. Upward convex curves are observed indicating that the process is advantageous towards boron adsorption. Moreover, the adjustment of experimental data to their corresponding functions leads to highly satisfactory correlations for all the studied conditions and pseudo-second-order kinetic model was observed. As for the mechanism of the adsorption process, a superficial process of chemosorption comprising three stages or reactions is proposed: 1) the hydration reaction of magnesium oxide as it is in contact with the aqueous solution to yield a magnesium hydroxide gel over the surface of which the active points for adsorption are located, 2) the alkalisation reaction of the solution due to the acid–base reaction between magnesium oxide and water and 3) the stereospecific chemical reaction between borate ions and active centres. This mechanism develops with time to reach stabilisation and leads to the formation of an adsorption monomolecular layer that is typical in chemosorption processes, as well as in systems following Langmuir adsorption isotherms and pseudo-second-order kinetics.
The boron removal capacity from an aqueous solution using MgAlFe mixed oxides from layered double hydroxides (LDH) was studied. They were synthesized by the coprecipitation method at 70 °C and were ...characterized as potential filter materials. The Fe3+ analyzed by X-ray photoelectron spectroscopy and UV–visible diffuse reflectance showed their tetrahedral and octahedral coordination. Scanning electron microscopy micrographs and thermogravimetric and differential scanning calorimetry analysis evidenced the presence of clusters and particles aggregates and decreased dehydroxylation temperature when the iron content increased. Mixed oxides and boron solution in a ratio of 20:1 Mg/B were put in a batch reactor at different contact times. The borate removal process was due to the memory effect of the mixed oxides and superficial adsorption by electrostatic attraction. This fact is directly related to the specific surface area, Fe content, and surface charge. The maximum boron removals were achieved with the CS25 and CS50 samples with values higher than 85%.
The presence of boron compounds in waters increases in a continuous and parallel way to industrial development. Therefore, their harmful effects on living organisms also increases, especially on ...plants, since this element manifests an important micronutrient–toxic boron duality. The aim of this study is to investigate the influence of different operation variables within the adsorption process of the boron compounds with magnesium oxide when liquid waste of urban, agricultural or industrial origin is being treated. The results obtained indicate that the process is strongly influenced by the quality of added reagent and by the contact time between the reagent and solution. Moreover, the temperature variable also stands out, as it has a very positive influence, reducing the necessary contact time to obtain specific boron removal yields. On the one hand, it has been observed that this process appears to be inextricably linked to pH. The removal process improves as the pH increases, presenting a maximum at pH value between 9.5 and 10.5, which is where borate ion predominates. The reagent used in the study has an important alkalinising capacity. Due to the fact that the pH of the solutions is situated around this range, it is not necessary to adjust this variable during the process. Therefore, using this reagent is an attractive option. As for the metallic cations that usually accompany boron in industrial waste, it seems that the reagent's presence also facilitates the removal of these cations and a simultaneous treatment of industrial waste can thus be carried out. Furthermore, interrelationships between the different variables have been established. When the optimum conditions are selected, the process reaches over 95% of boron removal.
The High Altitude Water Cherenkov (HAWC) gamma-ray observatory is located close to the equator (latitude
18
∘
N), at an altitude of 4100 m above sea level. HAWC has 295 water Cherenkov detectors ...(WCD), each containing four photomultiplier tubes (PMT). The main purpose of HAWC is the determination of the energy and arrival direction of very high energy gamma rays produced by energetic processes in the universe, HAWC also has a scaler system which counts the arrival of secondary particles to the detector. In this work we show that the scaler system of HAWC is an ideal instrument for solar modulation and space-weather studies due to its large area and high sensitivity. In order to prepare the scaler system for low energy heliospheric studies, we model and correct the efficiency variation of each PMT of the array, which result in a capability to measure variations
>
0.01
%
with high accuracy. Using the singular value decomposition method, we correct the rate deviations of all PMTs of the array, due to changes in efficiency, gain and operational voltage. We isolate and remove the atmospheric modulations of the PMTs count rates measured by the TDC-scaler data acquisition system. In particular, the atmospheric pressure at the HAWC site exhibits an oscillating behavior with a period of ∼12 hours and we make use of this periodic property to estimate the pressure coefficients for the HAWC TDC-scaler system. These corrections performed on the TDC-scaler system make the HAWC TDC-scaler system an ideal instrument for solar modulation and space-weather studies. As examples of this capability, we present the preliminary analysis of the solar modulation of cosmic rays at three time scales observed by HAWC, with an unprecedented accuracy.
People spend more than 90% of their time in indoor spaces, and, therefore, exposure to pollutants is high when inhabiting infrastructures with poor air quality. The pollutants present inside a ...building come either from inside the building itself (inhabitants, activity developed, etc), or from the outside (traffic, nearby industrial activity, etc). Among air cleaning techniques, building materials that incorporate a photocatalyst are considered to be a promising alternative. Photocatalysis is an Advanced Oxidation Process consisting of the oxidation/mineralization of pollutants in contact with a photocatalytic surface and the presence of UVA and sunlight irradiation. In this work, a photocatalytic paint based on TiO2 and active under indoor illumination conditions (ProCleanAir®, by PROQUICESA S.L.) was tested in a lecture room, evaluating the concentration of NO2 monitored by Palmes passive samplers. There was a decrease in the concentration of pollution after the application of the paint, with the depolluting effect remaining for one year, but also being dependent on atmospheric conditions. The statistical significance of the results was confirmed by t-student analyses.
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•A commercial photocatalytic paint tested at real scale (indoor).•NO2 removal efficiency measured by passive samplers.•Around 20% of NO2 removal efficiency recorded and validated by statistical analyses.•Photocatalytic activity mantained for a year after application of the paint.•Photocatalytic activity dependent on atmospheric conditions.
Abstract
Extended very-high-energy (VHE; 0.1–100 TeV)
γ
-ray emission has been observed around several middle-aged pulsars and referred to as “TeV halos.” Their formation mechanism remains under ...debate. It is also unknown whether they are ubiquitous or related to a certain subgroup of pulsars. With 2321 days of observation, the High Altitude Water Cherenkov (HAWC) Gamma-Ray Observatory detected VHE
γ
-ray emission at the location of the radio-quiet pulsar PSR J0359+5414 with >6
σ
significance. By performing likelihood tests with different spectral and spatial models and comparing the TeV spectrum with multiwavelength observations of nearby sources, we show that this excess is consistent with a TeV halo associated with PSR J0359+5414, though future observation of HAWC and multiwavelength follow-ups are needed to confirm this nature. This new halo candidate is located in a noncrowded region in the outer galaxy. It shares similar properties to the other halos but its pulsar is younger and radio-quiet. Our observation implies that TeV halos could commonly exist around pulsars and their formation does not depend on the configuration of the pulsar magnetosphere.
Cosmic rays, along with stellar radiation and magnetic fields, are known to make up a significant fraction of the energy density of galaxies such as the Milky Way. When cosmic rays interact in the ...interstellar medium, they produce gamma-ray emission which provides an important indication of how the cosmic rays propagate. Gamma-rays from the Andromeda galaxy (M31), located 785 kpc away, provide a unique opportunity to study cosmic-ray acceleration and diffusion in a galaxy with a structure and evolution very similar to the Milky Way. Using 33 months of data from the High Altitude Water Cherenkov Observatory, we search for teraelectronvolt gamma-rays from the galactic plane of M31. We also investigate past and present evidence of galactic activity in M31 by searching for Fermi bubble-like structures above and below the galactic nucleus. No significant gamma-ray emission is observed, so we use the null result to compute upper limits on the energy density of cosmic rays >10 TeV in M31.
The spectrum of COVID-19 infection includes acute respiratory distress syndrome (ARDS) and macrophage activation syndrome (MAS), although the histological basis for these disorders has not been ...thoroughly explored. Post-mortem pulmonary and bone marrow biopsies were performed in 33 patients. Samples were studied with a combination of morphological and immunohistochemical techniques. Bone marrow studies were also performed in three living patients. Bone marrow post-mortem studies showed striking lesions of histiocytic hyperplasia with hemophagocytosis (HHH) in most (16/17) cases. This was also observed in three alive patients, where it mimicked the changes observed in hemophagocytic histiocytosis. Pulmonary changes included a combination of diffuse alveolar damage with fibrinous microthrombi predominantly involving small vessels, in particular the alveolar capillary. These findings were associated with the analytical and clinical symptoms, which helps us understand the respiratory insufficiency and reveal the histological substrate for the macrophage activation syndrome-like exhibited by these patients. Our results confirm that COVID-19 infection triggers a systemic immune-inflammatory disease and allow specific therapies to be proposed.
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