Validación de la remoción de azo compuestos con carbón activado de exoesqueleto de camarón

El carbón activado (CA) es un material poroso, cuyos principales precursores son de origen vegetal, dichos precursores se componen de estructuras carbonosas, por ejemplo, la celulosa. Por otra parte, y derivado del uso del carbón activado en tratamientos de agua residual, se ha incursionado en usar precursores como el caucho y residuos de animales, aunque con algunas limitaciones. El exoesqueleto de camarón es un residuo generado en zonas costeras que no es reutilizado y que posee cantidades significativas de quitina, la cuál es el segundo polímero más abundante solo después de la celulosa. Por lo anterior, el objetivo del presente proyecto fue obtener carbón activado a partir de residuos de exoesqueleto de camarón para remover azo compuestos de muestras de agua. Se utilizó H3PO4  como agente activante al 20 %, 30 % y 40 %, además de evaluar la relación volumen-materia carbonosa. Las muestras a tratar fueron soluciones de azul de metileno a 1000 ppm, con ello se obtuvieron isotermas de adsorción, así como cinéticas de adsorción con respecto al tiempo y al efecto de la cantidad de CA utilizado. El mejor porcentaje de remoción de azul de metileno obtenido fue del 90.59 % con H3PO4 al 20 %, en tanto que en los parámetros fisicoquímicos evaluados en las muestras de agua a tratar no presentaron diferencias significativas

Microanálisis foliar de <i>Atriplex canescens</i> (Pursh) Nutt. bajo condiciones de salinidad

El déficit hídrico y la salinidad son las fuentes de estrés abiótico más limitantes en el aprovechamiento de los recursos vegetales. En la familia Chenopodiaceae en particular las especies del género Atriplex poseen adaptaciones que brindan ventajas en ambientes salinos. En México este género es considerado un importante recurso ecológico, sin embargo es escasa la información que se tiene sobre su fisiología. Con el objetivo de contribuir al conocimiento sobre sus adaptaciones, plántulas de 30 días de A. canescens fueron sometidas a salinidad durante 12, 24 y 48 horas y analizadas mediante MEB-EDS. Las imágenes revelaron que la superficie foliar posee abundantes tricomas con vacuolas de entre 10-70 μm, en donde la formación de cristales se ve promovida y delimitada. El microanálisis sugiere que estas vacuolas almacenan agua e iones de manera ordenada. Los más abundantes son el Cl-, Na+ y K+. El magnesio es el único elemento presente en todos los tiempos de exposición, lo que sugiere su importancia en el funcionamiento de la glándula. El Cl- y el K+ se detectan a las 12 horas de exposición, sin embargo; este último disminuye su concentración a las 48 horas y es remplazado gradualmente por Na+.Trabajo publicado en Acta Bioquímica Clínica Latinoamericana; no. 52, supl. 2, parte II, diciembre de 2018.Universidad Nacional de La Plat

Método a bajo costo para la cuantificación del grado alcohólico en muestras de tequila blanco

The green chemistry in the chemical analysis area consists of the design of qualitative or quantitative techniques that make a minimum generation of residues and have a validity in the results comparable to traditional methods. The microscale chemistry has had a relevant role in recent years in order to modify and implement new methodologies for the quantification of chemical analytes. In this project, a technique for quantifying the alcoholic content of tequila samples was developed based on the chemical principles of alcohol oxidation, which is a colorimetric technique that allows identifying the presence of an alcohol. The objective of the project was to apply the color change of the ethanol oxidation and to quantify it´s content based on the intensity of the blue color generated in the oxidation, using a low-cost photocolorimeter. The results were comparable with the obtained with a spectrophotometer, it was validated by a statistical method to know their reliability and finally, a correlation was made so that the same results were obtained with the proposed technique as with the commercial equipment.La química verde abordada en el área de los análisis químicos consiste en el diseño de técnicas cualitativas o cuantitativas que tengan una mínima generación de residuos y que permitan tener una validez en lo resultados comparable con métodos tradicionales. En este sentido, la química a microescala ha tenido un papel relevante en años recientes para poder modificar e implementar nuevas metodologías para la cuantificación de analitos químicos. En el presente proyecto se desarrolló una técnica de cuantificación del grado alcohólico de muestras de tequila basada en los principios químicos de la oxidación de alcoholes, la cual es una técnica colorimétrica que permite identificar la presencia de un alcohol. El objetivo del trabajo fue aprovechar el cambio de color de la oxidación del etanol y cuantificar el contenido alcohólico con base en la intensidad del color azul generado en la oxidación, mismo que se cuantificó con un fotocolorímetro a bajo costo y que mostró resultados comparables con los obtenidos con un espectrofotómetro, además que se realizó una validación estadística de los resultados para conocer la confiabilidad de los mismos y finalmente, se hizo una correlación para que con la técnica propuesta se obtuvieran los mismos resultados que con el equipo comercial

Centrality evolution of the charged-particle pseudorapidity density over a broad pseudorapidity range in Pb-Pb collisions at root s(NN)=2.76TeV

Peer reviewe

Coherent ψ(2S) photo-production in ultra-peripheral PbPb collisions at √sNN=2.76 TeV

We have performed the first measurement of the coherent ψ(2S) photo-production cross section in ultra-peripheral PbPb collisions at the LHC. This charmonium excited state is reconstructed via the ψ(2S)→l+l− and ψ(2S)→J/ψπ+π− decays, where the J/ψ decays into two leptons. The analysis is based on an event sample corresponding to an integrated luminosity of about 22 μb−1. The cross section for coherent ψ(2S) production in the rapidity interval −0.9<y<0.9 is dσψ(2S)coh/dy=0.83±0.19(stat+syst) mb. The ψ(2S) to J/ψ coherent cross section ratio is 0.34−0.07+0.08(stat+syst). The obtained results are compared to predictions from theoretical models

Freeze-out radii extracted from three-pion cumulants in pp, p–Pb and Pb–Pb collisions at the LHC

In high-energy collisions, the spatio-temporal size of the particle production region can be measured using the Bose-Einstein correlations of identical bosons at low relative momentum. The source radii are typically extracted using two-pion correlations, and characterize the system at the last stage of interaction, called kinetic freeze-out. In low-multiplicity collisions, unlike in high-multiplicity collisions, two-pion correlations are substantially altered by background correlations, e.g. mini-jets. Such correlations can be suppressed using three-pion cumulant correlations. We present the first measurements of the size of the system at freeze-out extracted from three-pion cumulant correlations in pp, p-Pb and Pb-Pb collisions at the LHC with ALICE. At similar multiplicity, the invariant radii extracted in p-Pb collisions are found to be 5-15% larger than those in pp, while those in Pb-Pb are 35-55% larger than those in p-Pb. Our measurements disfavor models which incorporate substantially stronger collective expansion in p-Pb as compared to pp collisions at similar multiplicity

Measurement of Λ(1520) production in pp collisions at √s = 7 TeV and p–Pb collisions at √sNN = 5.02 TeV

The production of the Λ(1520) baryonic resonance has been measured at midrapidity in inelastic pp collisions at s√ = 7 TeV and in p-Pb collisions at sNN−−−√ = 5.02 TeV for non-single diffractive events and in multiplicity classes. The resonance is reconstructed through its hadronic decay channel Λ(1520) → pK− and the charge conjugate with the ALICE detector. The integrated yields and mean transverse momenta are calculated from the measured transverse momentum distributions in pp and p-Pb collisions. The mean transverse momenta follow mass ordering as previously observed for other hyperons in the same collision systems. A Blast-Wave function constrained by other light hadrons (π, K, K0S, p, Λ) describes the shape of the Λ(1520) transverse momentum distribution up to 3.5 GeV/c in p-Pb collisions. In the framework of this model, this observation suggests that the Λ(1520) resonance participates in the same collective radial flow as other light hadrons. The ratio of the yield of Λ(1520) to the yield of the ground state particle Λ remains constant as a function of charged-particle multiplicity, suggesting that there is no net effect of the hadronic phase in p-Pb collisions on the Λ(1520) yield

Constraining the magnitude of the Chiral Magnetic Effect with Event Shape Engineering in Pb-Pb collisions at sNN\sqrt{s_{\rm NN}} = 2.76$ TeV

In ultrarelativistic heavy-ion collisions, the event-by-event variation of the elliptic flow $v_2$ reflects fluctuations in the shape of the initial state of the system. This allows to select events with the same centrality but different initial geometry. This selection technique, Event Shape Engineering, has been used in the analysis of charge-dependent two- and three-particle correlations in Pb-Pb collisions at $\sqrt{s_{_{\rm NN}}} =2.76$ TeV. The two-particle correlator $\langle \cos(\varphi_\alpha - \varphi_\beta) \rangle$, calculated for different combinations of charges $\alpha$ and $\beta$, is almost independent of $v_2$ (for a given centrality), while the three-particle correlator $\langle \cos(\varphi_\alpha + \varphi_\beta - 2\Psi_2) \rangle$ scales almost linearly both with the event $v_2$ and charged-particle pseudorapidity density. The charge dependence of the three-particle correlator is often interpreted as evidence for the Chiral Magnetic Effect (CME), a parity violating effect of the strong interaction. However, its measured dependence on $v_2$ points to a large non-CME contribution to the correlator. Comparing the results with Monte Carlo calculations including a magnetic field due to the spectators, the upper limit of the CME signal contribution to the three-particle correlator in the 10-50% centrality interval is found to be 26-33% at 95% confidence level

Constraining the magnitude of the chiral magnetic effect with event shape engineering in Pb–Pb collisions at √sNN=2.76 TeV

In ultrarelativistic heavy-ion collisions, the event-by-event variation of the elliptic flow v2 reflects fluctuations in the shape of the initial state of the system. This allows to select events with the same centrality but different initial geometry. This selection technique, Event Shape Engineering, has been used in the analysis of charge-dependent two- and three-particle correlations in Pb–Pb collisions at √sNN=2.76 TeV. The two-particle correlator 〈cos⁡(φα−φβ)〉, calculated for different combinations of charges α and β, is almost independent of v2 (for a given centrality), while the three-particle correlator 〈cos⁡(φα+φβ−2Ψ2)〉 scales almost linearly both with the event v2 and charged-particle pseudorapidity density. The charge dependence of the three-particle correlator is often interpreted as evidence for the Chiral Magnetic Effect (CME), a parity violating effect of the strong interaction. However, its measured dependence on v2 points to a large non-CME contribution to the correlator. Comparing the results with Monte Carlo calculations including a magnetic field due to the spectators, the upper limit of the CME signal contribution to the three-particle correlator in the 10–50% centrality interval is found to be 26–33% at 95% confidence level

Underlying-event properties in pp and p–Pb collisions at √sNN = 5.02 TeV

We report about the properties of the underlying event measured with ALICE at the LHC in pp and p−Pb collisions at sNN−−−√=5.02 TeV. The event activity, quantified by charged-particle number and summed-pT densities, is measured as a function of the leading-particle transverse momentum (ptrigT). These quantities are studied in three azimuthal-angle regions relative to the leading particle in the event: toward, away, and transverse. Results are presented for three different pT thresholds (0.15, 0.5, and 1 GeV/c) at mid-pseudorapidity (|η|10 GeV/c, whereas for lower ptrigT values the event activity is slightly higher in p−Pb than in pp collisions. The measurements are compared with predictions from the PYTHIA 8 and EPOS LHC Monte Carlo event generators