Screening of conditions controlling spectrophotometric sequential injection analysis

<p>Abstract</p> <p>Background</p> <p>Despite its potential benefits over univariate, chemometrics is rarely utilized for optimizing sequential injection analysis (SIA) methods. Specifically, in previous vis-spectrophotometric SIA methods, chemometrically optimized conditions were confined within flow rate and reagent concentrations while other conditions were ignored.</p> <p>Results</p> <p>The current manuscript reports, for the first time, a comprehensive screening of conditions controlling vis-spectrophotometric SIA. A new diclofenac assay method was adopted. The method was based on oxidizing diclofenac by permanganate (a major reagent) with sulfuric acid (a minor reagent). The reaction produced a spectrophotometrically detectable diclofenac form. The 2⁶full-factorial design was utilized to study the effect of volumes of reagents and sample, in addition to flow rate and concentrations of reagents. The main effects and all interaction order effects on method performance, i.e. namely sensitivity, rapidity and reagent consumption, were determined. The method was validated and applied to pharmaceutical formulations (tablets, injection and gel).</p> <p>Conclusions</p> <p>Despite 64 experiments those conducted in the current study were cumbersome, the results obtained would reduce effort and time when developing similar SIA methods in the future. It is recommended to critically optimize effective and interacting conditions using other such optimization tools as fractional-factorial design, response surface and simplex, rather than full-factorial design that used at an initial optimization stage. In vis-spectrophotometric SIA methods those involve developing reactions with two reagents (major and minor), conditions affecting method performance are in the following order: sample volume > flow rate ≈ major reagent concentration >> major reagent volume ≈ minor reagent concentration >> minor reagent volume.</p

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It is a standard practice to test for the signature of homologous recombination in studies examining the genetic diversity of bacterial populations. Although it has emerged that homologous recombination rates can vary widely between species, comparing the results from different studies is made difficult by the diversity of estimation methods used. Here, Multi Locus Sequence Typing (MLST) datasets from a wide variety of bacteria and archaea are analyzed using the ClonalFrame method. This enables a direct comparison between species and allows for a first exploration of the question whether phylogeny or ecology is the primary determinant of homologous recombination rate

Fossil record of Ephedra in the Lower Cretaceous (Aptian), Argentina

Fossil plants from the Lower Cretaceous (upper Aptian) of the La Cantera Formation, Argentina, are described. The fossils studied represent a leafy shooting system with several orders of articulated and striated axes and attached leaves with unequivocal ephedroid affinity. We also found associated remains of ovulate cones with four whorls of sterile bracts, which contain two female reproductive units (FRU). Ovulate cone characters fit well within the genus Ephedra. Special characters in the ovulate cones including an outer seed envelope with two types of trichomes, allowed us to consider our remains as a new Ephedra species. Abundant dispersed ephedroid pollen obtained from the macrofossil-bearing strata also confirms the abundance of Ephedraceae in the basin. The co-occurrence of abundant fossil of Ephedra (adapted to dry habitats) associated with thermophilic cheirolepideacean conifer pollen (Classopollis) in the unit would suggest marked seasonality at the locality during the Early Cretaceous. Furthermore, the floristic association is linked to dry sensitive rocks in the entire section. The macro- and microflora from San Luis Basin are similar in composition to several Early Cretaceous floras from the Northern Gondwana floristic province, but it may represent one of the southernmost records of an arid biome in South America.Fil: Puebla, Gabriela Griselda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; ArgentinaFil: Iglesias, Ari. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Gomez, Maria Angelica. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de San Luis. Facultad de Química, Bioquímica y Farmacia; ArgentinaFil: Pramparo, Mercedes Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Provincia de Mendoza. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales. Universidad Nacional de Cuyo. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales; Argentin

Bioinformatics and molecular biology for the quantification of closely related bacteria

10.1007/s00253-013-4943-5Applied Microbiology and Biotechnology97146489-6502AMBI