Retention-pH profiles of acids and bases in hydrophilic interaction liquid chromatography

The high proportion of acetonitrile used in many HILIC mobile phases significantly changes the acid-base properties of pH buffers and analytes foreseen from available data in water. In this paper, the recommended stability pH range for chromatographic columns is examined with various acetonitrile water mixtures, resulting in a significant broadening in the operational pH window with the content of organic solvent. Additionally, the challenge of buffer selection in HILIC is also addressed. Commonly used ammonium acetate shrinks its pH buffering range in acetonitrile-rich mobile phases due to variations in the dissociation constants of the buffer constituents (acetic acid and ammonium). Thus, other organic acids such as formic acid, TFA, and succinimide have been studied as buffers in order to fully cover the pH range of use of the column. Also the retention-pH profiles of several acids and bases have been studied in 80% and 90% acetonitrile using the proposed buffers and their behavior compared to that obtained with buffers prepared from oxalic acid, pyrrolidine, and triethylamine. The latter two show additional interactions in 80% acetonitrile that distort the expected retention-pH profiles of acid analytes, but not the ones of bases. In 90% acetonitrile the profiles are affected by significant additional solute-buffer interactions that might be caused by ion pairing, homo- and heteroassociation in this low ion solvating medium

Performance of global retention models in the optimisation of the chromatographic separation (I): Simple multi-analyte samples

Conventional retention models lead to accurate descriptions of the elution behaviour from the fitting of data for single solutes or from a set of solutes, one by one. However, the simultaneous fitting of several solutes through a regression process that separates the contributions of column and solvent from those of each solute is also possible. The result is a global retention model constituted by a set of equations with some common parameters (those associated with column and solvent), whereas others, specific to each solute, differ for each equation. This work explores the possibilities, advantages, and limitations of global models when they are applied to the optimisation of chromatographic resolution. A set constituted by 13 drugs (diuretics and β-blockers) and a training experimental design of seven multi-linear gradients are considered. Since standards for all compounds were available, the optimisation based on global models could be compared with the conventional optimisation, which is based on individual models. In their current state, global models do not predict changes in elution order, but they do allow for incorporating additional solutes (e.g., new analytes or matrix peaks) with only one new experiment. This possibility is explored by extending the model for the 13 analytes to include 26 peaks associated with a contamination in the injector. The combination of individual and global models allows an optimisation where the effects of matrix peaks on the separation of analytes can be integrated.Fil: Peiró Vila, P.. Universidad de Valencia; EspañaFil: Villamonte, María Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones Biológicas. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Instituto de Investigaciones Biológicas; ArgentinaFil: Luján Roca, I.. Universidad de Valencia; EspañaFil: Torres Lapasió, J.R.. Universidad de Valencia; EspañaFil: García Alvarez Coque, M. C.. Universidad de Valencia; Españ

Competències i habilitats transversals entre geologia i arqueologia prehistòrica

En aquest treball es desenvolupa una proposta concreta per abordar alguns dels objectius pedagògics, com ara la transversalitat, el treball en equip o la necessitat d'incrementar els coneixements pràctics. La perspectiva des de la que s'ha realitzat ha estat la de la col·laboració interdisciplinària entre docents universitaris que treballen en dos àmbits científics ben diferents: geologia i arqueologia prehistòrica.S'ha desenvolupat una eina pedagògica on els estudiants poden desenvolupar habilitats i capacitats com les esmentades a partir del seguiment d'un cas d'estudi concret: la determinació i procedència dels elements petris utilitzats en la construcció del sepulcre megalític de Puigseslloses (Osona). La proposta es basa en el seguiment i la participació dels estudiants en tot el procés de la recerca: el plantejament del problema historicoarqueològic, la definició de les vies d'estudi concretes, el seu desenvolupament, l'obtenció de resultats i la seva discussió interdisciplinària.En este trabajo se desarrolla una propuesta concreta para abordar algunos de los objetivos pedagógicos, como la transversalidad, el trabajo en equipo o la necesidad de incrementar los conocimientos prácticos. La perspectiva desde la que se ha realizado ha sido la de la colaboración interdisciplinaria entre docentes universitarios que trabajan en dos ámbitos científicos bien distintos: Geología y Arqueología Prehistórica. Se ha desarrollado una herramienta pedagógica a través de la cual los estudiantes pueden desarrollar habilidades y capacidades como las mencionadas a partir del seguimiento de un caso de estudio concreto: la determinación y procedencia de los elementos pétreos utilizados en la construcción del sepulcro megalítico de Puigseslloses (Osona). La propuesta se basa en que los estudiantes sigan y participen en todo el proceso de la investigación, desde el planteamiento del problema histórico-arqueológico, la definición de las vías de estudio concretas, su desarrollo y la obtención de resultados, hasta su discusión interdisciplinaria.This study develops a specific proposal for addressing some of the educational goals of the EHEA such as transversality, teamwork and the need to increase practical knowledge. The perspective from which the study was conducted was interdisciplinary cooperation among university professors who work in two quite different fields of science: geology and prehistoric archaeology. A pedagogical tool was developed in which students can develop skills and abilities such as the ones mentioned above by pursuing a specific case study: the description and provenance of stone elements used to build the megalithic sepulchre in Puigseslloses (Osona). The proposal is based on students' following and participating in the entire research process: posing the historical-archaeological problem, defining the specific avenues of study, conducting the study, getting the results and holding an interdisciplinary discussion of these results

Accuracy of colon capsule endoscopy in detecting colorectal polyps in individuals with familial colorectal cancer: could we avoid colonoscopies?

Background. Individuals with a family history of colorectal cancer (CRC) have an increased risk of CRC. We evaluated the diagnostic yield of CCE in the detection of lesions and also two different colon preparations. Methods. A prospective multicenter study was designed to assess CCE diagnostic yield in a cohort of asymptomatic individuals with a family history of CRC. CCE and colonoscopy were performed on the same day by 2 endoscopists who were blinded to the results of the other procedure. Results. Fifty-three participants were enrolled. The sensitivity, specificity, PPV, and NPV of CCE for detecting advanced adenomas were 100%, 98%, 67%, and 100%. Sensitivity, specificity, PPV, and NPV of CCE for the diagnosis of individuals with polyps were 87%, 97%, 93%, and 88%, respectively. CCE identify 100% of individuals with significant or advanced lesions. Overall cleanliness was adequate by 60.7% of them. The PEG-ascorbic boost seems to improve colon cleanliness, with similar colonic transit time. Conclusion. CCE is a promising tool, but it has to be considered as an alternative technique in this population in order to reduce the number of colonoscopies performed. More studies are needed to understand appropriate screening follow-up intervals and optimize the bowel preparation regimen

Evaluation of different bowel preparations for small bowel capsule endoscopy: a prospective, randomized, controlled study

To obtain an adequate view of the whole small intestine during capsule endoscopy (CE) a clear liquid diet and overnight fasting is recommended. However, intestinal content can hamper vision in spite of these measures. Our aim was to evaluate tolerance and degree of intestinal cleanliness during CE following three types of bowel preparation. PATIENTS AND METHODS: This was a prospective, multicenter, randomized, controlled study. Two-hundred ninety-one patients underwent one of the following preparations: 4 L of clear liquids (CL) (group A; 92 patients); 90 mL of aqueous sodium phosphate (group B; 89 patients); or 4 L of a polyethylene glycol electrolyte solution (group C; 92 patients). The degree of cleanliness of the small bowel was classified by blinded examiners according to four categories (excellent, good, fair or poor). The degree of patient satisfaction, gastric and small bowel transit times, and diagnostic yield were measured. RESULTS: The degree of cleanliness did not differ significantly between the groups (P = 0.496). Interobserver concordance was fair (k = 0.38). No significant differences were detected between the diagnostic yields of the CE (P = 0.601). Gastric transit time was 35.7 +/- 3.7 min (group A), 46.1 +/- 8.6 min (group B) and 34.6 +/- 5.0 min (group C) (P = 0.417). Small-intestinal transit time was 276.9 +/- 10.7 min (group A), 249.7 +/- 13.1 min (group B) and 245.6 +/- 11.6 min (group C) (P = 0.120). CL was the best tolerated preparation. Compliance with the bowel preparation regimen was lowest in group C (P = 0.008). CONCLUSIONS: A clear liquid diet and overnight fasting is sufficient to achieve an adequate level of cleanliness and is better tolerated by patients than other forms of preparation

Precise measurement of the W-boson mass with the CDF II detector

We have measured the W-boson mass MW using data corresponding to 2.2/fb of integrated luminosity collected in proton-antiproton collisions at 1.96 TeV with the CDF II detector at the Fermilab Tevatron collider. Samples consisting of 470126 W->enu candidates and 624708 W->munu candidates yield the measurement MW = 80387 +- 12 (stat) +- 15 (syst) = 80387 +- 19 MeV. This is the most precise measurement of the W-boson mass to date and significantly exceeds the precision of all previous measurements combined

Combined search for the standard model Higgs boson decaying to a bb pair using the full CDF data set

We combine the results of searches for the standard model Higgs boson based on the full CDF Run II data set obtained from sqrt(s) = 1.96 TeV p-pbar collisions at the Fermilab Tevatron corresponding to an integrated luminosity of 9.45/fb. The searches are conducted for Higgs bosons that are produced in association with a W or Z boson, have masses in the range 90-150 GeV/c^2, and decay into bb pairs. An excess of data is present that is inconsistent with the background prediction at the level of 2.5 standard deviations (the most significant local excess is 2.7 standard deviations).Comment: To be published in Phys. Rev. Lett (v2 contains minor updates based on comments from PRL

Observation of Orbitally Excited B_s Mesons

We report the first observation of two narrow resonances consistent with states of orbitally excited (L=1) B_s mesons using 1 fb^{-1} of ppbar collisions at sqrt{s} = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We use two-body decays into K^- and B^+ mesons reconstructed as B^+ \to J/\psi K^+, J/\psi \to \mu^+ \mu^- or B^+ \to \bar{D}^0 \pi^+, \bar{D}^0 \to K^+ \pi^-. We deduce the masses of the two states to be m(B_{s1}) = 5829.4 +- 0.7 MeV/c^2 and m(B_{s2}^*) = 5839.7 +- 0.7 MeV/c^2.Comment: Version accepted and published by Phys. Rev. Let

Precision Top-Quark Mass Measurements at CDF

We present a precision measurement of the top-quark mass using the full sample of Tevatron $\sqrt{s}=1.96$ TeV proton-antiproton collisions collected by the CDF II detector, corresponding to an integrated luminosity of 8.7 $fb^{-1}$. Using a sample of $t\bar{t}$ candidate events decaying into the lepton+jets channel, we obtain distributions of the top-quark masses and the invariant mass of two jets from the $W$ boson decays from data. We then compare these distributions to templates derived from signal and background samples to extract the top-quark mass and the energy scale of the calorimeter jets with {\it in situ} calibration. The likelihood fit of the templates from signal and background events to the data yields the single most-precise measurement of the top-quark mass, \mtop = 172.85 \pm$0.71 (stat)$\pm$0.85 (syst) GeV/c^{2}.$Comment: submitted to Phys. Rev. Let

A search for resonant production of ttˉt\bar{t} pairs in $4.8\ \rm{fb}^{-1}ofintegratedluminosityof of integrated luminosity of p\bar{p}collisionsat collisions at \sqrt{s}=1.96\ \rm{TeV}$

We search for resonant production of tt pairs in 4.8 fb^{-1} integrated luminosity of ppbar collision data at sqrt{s}=1.96 TeV in the lepton+jets decay channel, where one top quark decays leptonically and the other hadronically. A matrix element reconstruction technique is used; for each event a probability density function (pdf) of the ttbar candidate invariant mass is sampled. These pdfs are used to construct a likelihood function, whereby the cross section for resonant ttbar production is estimated, given a hypothetical resonance mass and width. The data indicate no evidence of resonant production of ttbar pairs. A benchmark model of leptophobic Z \rightarrow ttbar is excluded with m_{Z'} < 900 GeV at 95% confidence level.Comment: accepted for publication in Physical Review D Sep 21, 201