Comparison of moisture management methods for the bioremediation of hydrocarbon contaminated soil

Different moisture management methods were compared for  biodegradation efficiency in sandy and organic soils. The conventional method consisted in maintaining the soil moisture at approximately 50to 75% field capacity accompanied by daily aeration and mixing. In the test method, the soil was allowed to dry out completely for three to four days after which the soil was moistened to 50 to 75% of field capacity and mixed daily for five days. In the test method the drying and moisturizing cycles were maintained throughout the experiment. There was no difference in treatments in the sandy soil, both treatments resulting in the detoxification to background levels within five weeks. During the processingof the organic soil, an increase in toxicity was observed, apparently due to increased availability of hydrocarbons, and possibly due to the production of toxic intermediates of biodegradation. The transformation rate in the test method was 22% less than in the conventional method, although thistransformation started at least four weeks earlier than in the conventional method. Based on these observations, a combination of drying (to increase bioavailability) and conventional moisture management (to stimulate hydrocarbon degrading microorganisms) is recommended.Key words: Remediation, toxicity, petroleum

Comparación de tres métodos moleculares para el análisis de procariontes ambientales en el mar del canal de Yucatán, México

In this study we describe a prokaryotic community from a seawater sample obtained in the Yucatan Channel, using for this purpose three molecular methods: 1) T-RFLPs. 2) Sequencing of amplicons (clone libraries). 3) Metagenome shotgun sequencing; the three are useful for the determination of microbial diversity. We also present a comparison of the scope and limits of each method. The comparison took into account three criteria: the number of taxonomic units detected, the taxonomic assignment accuracy and the cost of the study. The most abundant taxa were Candidatus Portiera OTU 3744 (equivalent to SAR86 clade) and Candidatus Pelagibacter. The results showed that the shotgun sequencing strategy is the most powerful in terms of detected taxonomic units, while the data obtained by T-RFLPs and clone library methods represent only a subsample of the shotgun fragment library. Regarding phylogenetic resolution (taxonomical determination), the more accurate approach is the sequencing of clone libraries. The costs of the three strategies vary considerably, but so does its scope. Therefore, it is important to consider that one, or another methodology, can only specifically answer some ecological and evolutionary questions.En este trabajo describimos la comunidad procarionte de una muestra de agua marina del canal de Yucatán. Para la determinación de la diversidad microbiana se usaron tres métodos moleculares: 1) T-RFLPs. 2) Secuenciación de amplicones (bibliotecas de clones). 3) Secuenciación shotgun de un metagenoma. Como un segundo objetivo, se presenta una comparación de los alcances y los límites de cada uno de estos tres métodos. Para esta comparación, se tomaron en cuenta tres criterios: el número de unidades taxonómicas detectadas, la precisión en la asignación taxonómica y el costo del estudio. Los taxa más abundantes fueron Candidatus Portiera OTU 3744 (equivalente al clado SAR86) y Candidatus Pelagibacter. Los resultados mostraron que la estrategia de secuenciación shotgun de ADN es la más poderosa en términos de unidades taxonómicas detectadas, mientras que los datos que se obtuvieron por T-RFLPs y con la biblioteca de clones, representan sólo una submuestra de la biblioteca de fragmentos generados mediante shotgun. En cuanto a resolución filogenética (determinación taxonómica), la aproximación más precisa fue la secuenciación de bibliotecas de clones. Los costos de las tres estrategias varían considerablemente, pero sus alcances también lo hacen. Por lo tanto, es importante tomar en consideración que algunas preguntas ecológicas y evolutivas sólo pueden ser contestadas específicamente por una u otra metodología

Constraints on the χ_(c1) versus χ_(c2) polarizations in proton-proton collisions at √s = 8 TeV

The polarizations of promptly produced χ_(c1) and χ_(c2) mesons are studied using data collected by the CMS experiment at the LHC, in proton-proton collisions at √s=8  TeV. The χ_c states are reconstructed via their radiative decays χ_c → J/ψγ, with the photons being measured through conversions to e⁺e⁻, which allows the two states to be well resolved. The polarizations are measured in the helicity frame, through the analysis of the χ_(c2) to χ_(c1) yield ratio as a function of the polar or azimuthal angle of the positive muon emitted in the J/ψ → μ⁺μ⁻ decay, in three bins of J/ψ transverse momentum. While no differences are seen between the two states in terms of azimuthal decay angle distributions, they are observed to have significantly different polar anisotropies. The measurement favors a scenario where at least one of the two states is strongly polarized along the helicity quantization axis, in agreement with nonrelativistic quantum chromodynamics predictions. This is the first measurement of significantly polarized quarkonia produced at high transverse momentum