Application of the Rietveld Method to Quantify Mineral Phases in a Kaolin Mineral

The applications of the mineral kaolin are varied, such as the ceramic industry, and the pharmaceutical industry, among others; although it is generally found in mining deposits accompanied by other mineral species considered contaminants. The above makes it necessary to apply qualitative and quantitative analysis techniques that determine the purity of the mineral, from its extraction, during its mechanical processing and kaolin recovery. In this work, a procedure for quantification of the majority species in the Kaolin mineral is proposed, according to the procedure proposed by Rietveld, from the diffractogram obtained by the x-ray diffraction technique, as well as the knowledge of the crystallographic characteristics of the mineral constituents. Three models are proposed based on the structural parameters of the phases present in the system: tridymite, cristobalite, and kaolinite. The experimental results show the total adjustment of the diffraction pattern in which it is observed that the weight percentage corresponds to 40.0% for tridymite, 39.5% for cristobalite, and 20.5% for kaolinite. These results were corroborated by specific semi-quantitative chemical analyses using scanning electron microscopy.&nbsp

Deinking of Mixed Office Waste (MOW) Paper Using Enzymes

Deinking of Mixed Office Waste [MOW] paper was carried out by using a flotation device and adding enzymes as defibrillators. Employing the computational simulation of the molecular coupling between the cellulase enzyme obtained from Trichoderma sp. and cellulose, the enzyme-cellulose molecular complex and the main amino acids endo-β-1,4-D-glucanase of this molecule, responsible for the hydrolysis of cellulose, were obtained. Three of these amino acids were used for deinking. The deinked cellulose fibers were evaluated according to the standards of the paper industry (ISO whiteness [brightness], factor of reflectance, opacity, and tonality) to determine the efficiency of deinking. The experimental results show that the best optical characteristics of the sheets of deinked paper with amino acids are those where a mixture of aspartate, glutamate, and asparagine was applied, instead of their individual dosage. In addition to the aforesaid, the use of enzymes instead of the traditionally used reagent, such as sodium hydroxide, avoids the contamination of wastewater; additionally, the operation of the column is carried out easily, taking into consideration that the pH of the system goes from alkaline to neutral

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality

Surface Spectroscopy of Pyrite Obtained during Grinding and Its Magnetisation

During grinding with forged steel media, sulphides such as pyrite undergo surface changes due to the occurrence of oxidation–reduction reactions, which affect its depression during the concentration process. For this reason, in this work, the surface modification of pyrite during grinding was studied; FTIR, ICP-OES, XRD and SEM-EDS were used for the materials’ characterisation. It was found that the pyrite obtained during grinding showed magnetic susceptibility due to the absorption and superficial formation of magnetite Fe3O4, Fe–O bonds identified by FTIR at 598 cm−1, and of other species, such as oxy-hydroxy-sulphates at 696 cm−1 and goethite α-FeOOH at 875 cm−1. This caused the reversal of the zeta potential magnitude (ζ) from positive to negative at pH 8.3 and 30 min of grinding. The ζ of the pyrite throughout the studied pH ranges was, overall, positive, i.e., +5 mV. However, at pH 10.5 and 15 min of grinding, the ζ turned negative. This was associated with the formation of Fe–CO3 (−2) bonds in the siderite, which were identified with the absorption bands corresponding to 756, 1448 and 1493 cm−1

Surface Spectroscopy of Pyrite Obtained during Grinding and Its Magnetisation

During grinding with forged steel media, sulphides such as pyrite undergo surface changes due to the occurrence of oxidation–reduction reactions, which affect its depression during the concentration process. For this reason, in this work, the surface modification of pyrite during grinding was studied; FTIR, ICP-OES, XRD and SEM-EDS were used for the materials’ characterisation. It was found that the pyrite obtained during grinding showed magnetic susceptibility due to the absorption and superficial formation of magnetite Fe3O4, Fe–O bonds identified by FTIR at 598 cm−1, and of other species, such as oxy-hydroxy-sulphates at 696 cm−1 and goethite α-FeOOH at 875 cm−1. This caused the reversal of the zeta potential magnitude (ζ) from positive to negative at pH 8.3 and 30 min of grinding. The ζ of the pyrite throughout the studied pH ranges was, overall, positive, i.e., +5 mV. However, at pH 10.5 and 15 min of grinding, the ζ turned negative. This was associated with the formation of Fe–CO3 (−2) bonds in the siderite, which were identified with the absorption bands corresponding to 756, 1448 and 1493 cm−1