Estudio de la especiación de disoluciones hidrolizadas mixtas Al-Fe en medio concentrado con el reactivo Ferrón.

Introducción. La obtención de disoluciones concentradas de aluminio con alta fracción de oligocationes presenta gran interés por su aplicabilidad como floculantes en el tratamiento de aguas y como agentes de intercalación de arcillas laminares. El análisis espectrofotométrico con el reactivo Ferrón permite obtener una distribución de las especies que se generan en disoluciones parcialmente hidrolizadas de Al3+, en base a su grado de polimerización. El propósito de este trabajo es evaluar el efecto de la relación de hidrólisis OH/(Al+Fe) (RH) y la concentración total de metales (CTM) sobre la preparación de disoluciones hidrolizadas de Al/Fe en medio concentrado. Para ello, se toma como criterio el contenido de los metales que queda representado al final en especies tipo Keggin (Al13), correspondiente a la fracción Alb obtenida mediante el análisis con el reactivo Ferrón [1]. Metodología. El efecto de la CTM y de la RH sobre la preparación de las disoluciones concentradas mixtas Al/Fe (DCMAF), se evaluó aplicando un diseño experimental 32, manteniendo constante la relación atómica nominal (Fe/(Al+Fe)) igual a 2,0. Cada factor se evaluó en tres niveles: para el factor CTM se emplearon los valores 0,2, 0,6 y 1,0 mol/L, mientras para el factor RH se tomaron los valores 2,0, 2,25 y 2,5. La preparación de las disoluciones se llevó a cabo partiendo de AlCl3.6H2O (Sigma Aldrich, 99,9%) y FeCl3.6H2O (Mallinckrodt, 99,5%) con lenta adición de disolución de hidróxido de sodio de concentración variable (Mallinckrodt, 99,8%), en un sistema de reflujo a 70 ºC durante 7,75 horas. Las disoluciones fueron filtradas en papel con tamaño de poro 0,45 μm para separar la fracción insoluble antes de ser analizadas. Para el análisis con el reactivo Ferrón (Sigma Aldrich, 98,5%) se empleó como patrón una disolución de concentración conocida de Al13, separado por precipitación del sulfato seguida de disolución del nitrato del oligocatión. La identidad del patrón se confirmó por difracción de rayos X en polvo. Las fracciones de Ala y Alb se determinaron midiendo la absorbancia a 364 nm a 1 y 120 minutos de reacción, respectivamente. Ala corresponde a la fracción de especies monoméricas, Alb a la fracción oligomérica soluble, y Alc a la fracción polimérica coloidal, calculada como Alc = AlT – (Ala + Alb). Resultados y discusión. La distribución de especies obtenida mediante el análisis con el reactivo Ferrón se muestra en la tabla 1. Tabla 1. Especiación de disoluciones concentradas mixtas Al/Fe (DCMAF) Los resultados muestran que a menor RH se favorece la fracción de especies poliméricas solubles Alb, aunque este efecto es menos marcado en cuanto baja CTM. Igualmente se observa, que con el aumento en CTM, Alb disminuye para un valor de RH. Cuando se incrementa CTM también se puede observar, que aunque baja el pH de equilibrio de las disoluciones se incrementa la fracción de polímeros inertes o coloidales de los metales, que corresponde a la fracción Alc con Ferrón. Conclusiones. La preparación de DCMAF con alto contenido de Al13 en medio concentrado se favorece con la disminución de RH. Bibliografía. 1. Parker, D.R. (1992). Identification and quantification of the “Al13” tridecameric polycation using ferron. Env. Sci. Technol. 26:908–914. Agradecimientos. Los autores agradecen la financiación de este trabajo a EMPOPASTO S.A, E.S.P mediante convenio específico de cooperación No 01 de 2008

Insecticide Resistance Mechanisms in the Green Peach Aphid Myzus persicae (Hemiptera: Aphididae) II: Costs and Benefits

feeds upon a huge diversity of hosts, it has been exposed to a wide variety of plant allelochemicals, which probably have promoted a wide range of detoxification systems. on both hosts, but they increased the transcriptional levels of two genes. than susceptible genotypes on radish, the more unfavorable host. Susceptible genotypes should be able to tolerate the defended host by up-regulating some metabolic genes that are also responding to insecticides. Hence, our results suggest that the trade-off among resistance mechanisms might be quite complex, with a multiplicity of costs and benefits depending on the environment

Photospheric observations of surface and body modes in solar magnetic pores

Over the past number of years, great strides have been made in identifying the various low-order magnetohydrodynamic wave modes observable in a number of magnetic structures found within the solar atmosphere. However, one aspect of these modes that has remained elusive, until now, is their designation as either surface or body modes. This property has significant implications for how these modes transfer energy from the waveguide to the surrounding plasma. Here, for the first time to our knowledge, we present conclusive, direct evidence of these wave characteristics in numerous pores that were observed to support sausage modes. As well as outlining methods to detect these modes in observations, we make estimates of the energies associated with each mode. We find surface modes more frequently in the data, as well as that surface modes appear to carry more energy than those displaying signatures of body modes. We find frequencies in the range of ~2–12 mHz, with body modes as high as 11 mHz, but we do not find surface modes above 10 mHz. It is expected that the techniques we have applied will help researchers search for surface and body signatures in other modes and in differing structures from those presented here

Prevention of haematoma progression by tranexamic acid in intracerebral haemorrhage patients with and without spot sign on admission scan: a statistical analysis plan of a pre-specified sub-study of the TICH-2 trial

Objective We present the statistical analysis plan of a prespecified Tranexamic Acid for Hyperacute Primary Intracerebral Haemorrhage (TICH)-2 sub-study aiming to investigate, if tranexamic acid has a different effect in intracerebral haemorrhage patients with the spot sign on admission compared to spot sign negative patients. The TICH-2 trial recruited above 2000 participants with intracerebral haemorrhage arriving in hospital within 8 h after symptom onset. They were included irrespective of radiological signs of on-going haematoma expansion. Participants were randomised to tranexamic acid versus matching placebo. In this subgroup analysis, we will include all participants in TICH-2 with a computed tomography angiography on admission allowing adjudication of the participants’ spot sign status. Results Primary outcome will be the ability of tranexamic acid to limit absolute haematoma volume on computed tomography at 24 h (± 12 h) after randomisation among spot sign positive and spot sign negative participants, respectively. Within all outcome measures, the effect of tranexamic acid in spot sign positive/negative participants will be compared using tests of interaction. This sub-study will investigate the important clinical hypothesis that spot sign positive patients might benefit more from administration of tranexamic acid compared to spot sign negative patients

Trabecular Meshwork Gene Expression after Selective Laser Trabeculoplasty

BACKGROUND: Trabecular meshwork and Schlemm's canal are the tissues appointed to modulate the aqueous humour outflow from the anterior chamber. The impairment of their functions drives to an intraocular pressure increase. The selective laser trabeculoplasty is a laser therapy of the trabecular meshwork able to decrease intraocular pressure. The exact response mechanism to this treatment has not been clearly delineated yet. The herein presented study is aimed at studying the gene expression changes induced in trabecular meshwork cells by selective laser trabeculoplasty (SLT) in order to better understand the mechanisms subtending its efficacy. METHODOLOGY/PRINCIPAL FINDINGS: Primary human trabecular meshwork cells cultured in fibroblast medium underwent selective laser trabeculoplasty treatment. RNA was extracted from a pool of cells 30 minutes after treatment while the remaining cells were further cultured and RNA was extracted respectively 2 and 6 hours after treatment. Control cells stored in incubator in absence of SLT treatment were used as reference samples. Gene expression was evaluated by hybridization on miRNA-microarray and laser scanner analysis. Scanning electron microscopic examination was performed on 2 Trabecular meshwork samples after SLT at 4(th) and 6(th) hour from treatment. On the whole, selective laser trabeculoplasty modulates in trabecular meshwork the expression of genes involved in cell motility, intercellular connections, extracellular matrix production, protein repair, DNA repair, membrane repair, reactive oxygen species production, glutamate toxicity, antioxidant activities, and inflammation. CONCLUSIONS/SIGNIFICANCE: SLT did not induce any phenotypic alteration in TM samples. TM is a complex tissue possessing a great variety of function pivotal for the active regulation of aqueous humour outflow from the anterior chamber. SLT is able to modulate these functions at the postgenomic molecular level without inducing damage either at molecular or phenotypic levels

Transancestral mapping and genetic load in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is an autoimmune disease with marked gender and ethnic disparities. We report a large transancestral association study of SLE using Immunochip genotype data from 27,574 individuals of European (EA), African (AA) and Hispanic Amerindian (HA) ancestry. We identify 58 distinct non-HLA regions in EA, 9 in AA and 16 in HA (B50% of these regions have multiple independent associations); these include 24 novel SLE regions (Po5 10 8), refined association signals in established regions, extended associations to additional ancestries, and a disentangled complex HLA multigenic effect. The risk allele count (genetic load) exhibits an accelerating pattern of SLE risk, leading us to posit a cumulative hit hypothesis for autoimmune disease. Comparing results across the three ancestries identifies both ancestry-dependent and ancestry-independent contributions to SLE risk. Our results are consistent with the unique and complex histories of the populations sampled, and collectively help clarify the genetic architecture and ethnic disparities in SL

Mechanical stability of the CMS strip tracker measured with a laser alignment system

Peer reviewe