Chitosan-coated magnetic nanoparticles (CMNP) were obtained at 50 • C in a one-step method comprising coprecipitation in the presence of low chitosan content. CMNP showed high magnetization and superparamagnetism. They were composed of a core of 9.5 nm in average diameter and a very thin chitosan layer in accordance with electron microscopy measurements. The results from Fourier transform infrared spectrometry demonstrated that CMNP were obtained and those from thermogravimetric analysis allowed to determine that they were composed of 95 wt% of magnetic nanoparticles and 5 wt% of chitosan. 67% efficacy in the Pb +2 removal test indicated that only 60% of amino groups on CMNP surface bound to Pb, probably due to some degree of nanoparticle flocculation during the redispersion. The very low weight ratio chitosan to magnetic nanoparticles obtained in this study, 0.053, and the high yield of the precipitation reactions (≈97%) are noticeable.

Aguamiel is a beverage produced by some species that is consumed in its fresh or fermented form. Despite its uses and popularity, seasonal effects on its microbial and chemical profiles are unknown. In this study, using aguamiel collected from and during different seasons, we identified microorganisms by sequencing the 16S and 18S rDNA genes and determined their chemical profiles. In total, 49 microbial strains were identified (38 bacteria and 11 yeasts). The highest richness and biodiversity were observed during winter and summer. Different lactic acid bacteria and yeast genera with potential industrial applications were identified, such as, ,, and . The analysis of the chemical profiles indicated the presence of maltooligosaccharides and fructooligosaccharides, which are associated with human health improvements, during spring in aguamiel. Aguamiel can be used in the food industry due to its microbiological and chemical profiles.

Salinity in soils is a problem that has increased in recent years, in the Mexican southeast one of the main sources associated with these effects is the oil production water, affected congenital water. Although the chemical composition changes between one site and another, it is documented that its components can cause harmful effects on health and ecosystems. To recover the vocation to use recovery areas, different treatments have been established that eliminate standardized parameters, but others that may influence soil quality are not considered. Therefore, two treatment techniques of a soil contaminated experimentally with congenital waters were evaluated, these were; cation exchange and natural attenuation, the evaluation consists in comparing the physical and chemical properties of the control soil, treated and treated after one year, some heavy metals are also determined in all of them. In the results, it is modif ied that the pollutant causes changes in the soil, such as, pH reduction (neutral to acid), porosity (20%), f ield capacity (50%) and organic matter (50%), as well as an increase in salinity (without saline to saline) and densities (10%), it is also increased that the concentrations of Pb, Zn, Ni increase. Na, Fe and V and Ca and K were reduced. Both treatments reduce salinity, but natural attenuation shows better results than cation exchange, mainly in pH, f ield capacity and textures, but with higher concentrations of sodium with respect to the witness in both cases, the metals are below the regulatory limit before and after the treatment, but when compared with control soils a level of increase in V and Pb is noted, because the area is immersed in oil activities, it is advisable to carry out long-term bioaccumulation studies.

KEYWORDSIn this work, principal component regression and partial least squares regression were used for the estimation of acid dissociation constants through UV-Vis spectrophotometric measurements, considering five well-known acid-base indicators as well as two herbicides as analytes. In each case, an acid-base titration was carried out. Then, the multivariate calibration model was constructed with a few absorption spectra of the series at extreme pH values, to which values of the dissociation fraction (α) of 1 or 0 were assigned, in the case of HA or A species. After that, the prediction step consisted in the estimation of α for the rest of the series. Then, distribution diagrams were built up with α vs pH, to find α = 0.5 where pH = pKa. The results were compared with those obtained through multivariate curve resolutionalternating least squares and program stability quotients from absorbance data (SQUAD), which showed an excellent correspondence. pKa PLS PCR MCR-ALS Spectrophotometry Chemometric strategies

totales del petróleo intemperizados en suelos y sedimentos (Biodegradation modeling of sludge bioreactors of total petroleum hydrocarbons weathering in soil and sediments)

An overview of current Mexican legislation regarding soil restoration and updating needs is made through the analysis of three case studies located in the southeastern México: a) soil affected by spillage of congenital waters (Zone 1), b) soil contaminated by hydrocarbons (Zone 2) and, c) a site adjacent to urban infrastructure (Zone 3). It was performed a comparative analysis of the soils conditions in the short and long term after the anthropogenic impact and restoration process that were carried out in each studied location. It was found that important properties of the soils do not recover after the weathering process, for instance in Zone 1, DR and DA as well as %Po did not reach equivalent values to the control sample and the soil texture is different even after a long recovery period. For Zone 2, it was detected important variations in the concentration of Ca, Na and K in both the impacted and recovered soils which affect the growth of plantations. In Zone 3, there were found signif icative differences in DA, %Po; %L, %R, %MO and CEC parameters. The current normative considers general aspects, but does not contemplate the actual site situation, there is an information gap due to this, although it was observed achievement of physical and chemical properties for the recovery soil use in each site, it was also noticed that the evaluations do not consider if these properties can change over time due to weather conditions, therefore, they could influence the success of each restoration process in the long term. The information generated can be used to make decisions about government rescue programs for the primary sector or as a starting point in the implementation of Environmental Bases Lines (LBA) for the hydrocarbon sector.

Actualmente la urbanización y el crecimiento poblacional han aumentado la demanda de agua, provocando escases en diferentes regiones del país. Uno de los procesos de recolección de agua es la cosecha de lluvia que consiste en recolectar, almacenar y tratar la escorrentía de techos, azoteas y superficies impermeables. Esta agua puede utilizarse como fuente adicional a un sistema de suministro de agua, sin embargo, la calidad del agua recolectada puede verse afectada por la presencia de contaminantes en las superficies en contacto con el agua. El objetivo de este trabajo fue evaluar la calidad del agua de lluvia cosechada en la azotea de una vivienda ubicada en el Fracc. Mirasierra, en la ciudad de Saltillo Coahuila, donde se recolectaron doce muestras de agua. Para su caracterización química se utilizaron técnicas gravimétricas, volumétricas y espectrofotométricas establecidas por normas mexicanas, encontrando que el plomo sobrepasa la concentración del límite permisible establecido por la NOM-127-SSA1-2021 ya que presenta concentraciones mayores de 0.2 mg/L.

En este trabajo, se caracterizó el color de lacas acrílicas blancas utilizadas para retocar pintura automotriz, mediante el espacio de color CIELab y el índice de blancura, utilizando el iluminante estándar D65 y el observador estándar a diez grados. A partir de tal información, fue posible reconocer las tendencias del color usado en este tipo de productos en el mercado nacional. Por otra parte, la aplicación de las técnicas quimiométricas de Análisis de Componentes Principales, Análisis de Grupos y Análisis Jerárquico, permitió reconocer semejanzas entre los colores observados, encontrando, entre otros, la mayor diferencia visual en la laca de blanco aperlado. Por otro lado, la laca de blanco Alaska de Mazda y la de blanco universal de Nissan fueron las más parecidas. También se concluye que el análisis cromático y el quimiométrico de datos espectrales fueron complementarios, por lo que se recomiendan ambos en el nivel de control de calidad.