Optimization of gastroretentive system for oral controlled delivery of cinnarizine using response surface methodology

Se propone un sistema fl otante efervescente de liberación controlada para la administración gastrorretentiva de cinarizina. Para producir comprimidos de cinarizina fl otantes de liberación controlada mediante compresión directa se utilizó un diseño de Box-Behnken 33. Se estudiaron los efectos de variables de formulación como los niveles de HPMC K4M (X1), bicarbonato sódico (X2) y ácido cítrico (X3) en las características de fl otabilidad del comprimido y la liberación de fármaco. Los parámetros de respuesta como el tiempo de fl otabilidad total (TFT), la liberación al cabo de 10 h (Rel10), el tiempo necesario para la liberación del 50% del fármaco (t50) y el exponente de difusión de Korsemeyer y Peppas (n), se analizaron mediante la metodología de superfi cie de respuesta. Los parámetros se analizaron mediante el test F, y se generaron modelos matemáticos para cada parámetro de respuesta mediante análisis de regresión lineal múltiple (MLRA) y análisis de varianza (ANOVA). Las tres variables de formulación estudiadas tuvieron un efecto signifi cativo (P < 0,05) en el TFT, mientras que los niveles de HPMC K4M y ácido cítrico infl uyeron signifi cativamente en la liberación de fármaco. Para desarrollar una formulación optimizada se utilizó la optimización numérica con enfoque de deseabilidad, estableciendo restricciones en las variables dependientes e independientes. La formulación optimizada presentó una liberación de fármaco del 82,37 % durante el TFT de 8,5 h en modo de orden cero un valor de t50 de 5,30 h. Los valores experimentales del TFT, t50 y Rel10 observados concordaban con los predichos por los modelos matemáticos, confi rmando la predictabilidad de MLRA y ANOVA.A controlled release effervescent fl oating system is proposed for gastroretentive delivery of cinnarizine. A 33 box-behnken design was employed to produce controlled release fl oating tablets of cinnarizine by direct compression method. The effect of the formulation variables such as levels of HPMC K4M (X1), sodium bicarbonate (X2) and citric acid (X3) on the tablet fl oating characteristics and drug release was studied. The response parameters like total fl oating time (TFT), release at the end of 10 h (Rel10), time taken for 50% of the drug to release (t50) and Korsemeyer and Peppas diffusion exponent (n) were analyzed using response surface methodology. The parameters were analyzed using the F test and mathematical models were generated for each response parameter using multiple linear regression analysis (MLRA) and analysis of variance (ANOVA). All the three formulation variables studied had a signifi cant effect (P < 0.05) on the TFT whereas the levels of HPMC K4M and citric acid signifi cantly infl uenced the drug release. Numerical optimization employing desirability approach was used to develop an optimized formulation by setting constraints on the dependent and independent variables. The optimized formulation showed 82.37 % drug release during the TFT of 8.5 h in a zero order fashion with a t50 of 5.30 h. The experimental values of the TFT, t50 and Rel10 were found to agree with those predicted by the mathematical models confi rming the fore casting ability of MLRA and ANOVA

Triggered Star Formation

Triggered star formation in bright rims and shells is reviewed. Shells are commonly observed in the Milky Way and other galaxies, but most diffuse shells seen in HI or the infrared do not have obvious triggered star formation. Dense molecular shells and pillars around HII regions often do have such triggering, although sometimes it is difficult to see what is triggered and what stars formed in the gas before the pressure disturbances. Pillar regions without clear age gradients could have their stars scattered by the gravity of the heads. Criteria and timescales for triggering are reviewed. The insensitivity of the average star formation rate in a galaxy to anything but the molecular mass suggests that triggering is one of many processes that lead to gravitational collapse and star formation.Comment: 16 pages, 4 figures, Ecole Evry Schatzman 2010: Star Formation in the Local Universe. Lecture 4 of

Measurement of the p-pbar -> Wgamma + X cross section at sqrt(s) = 1.96 TeV and WWgamma anomalous coupling limits

The WWgamma triple gauge boson coupling parameters are studied using p-pbar -> l nu gamma + X (l = e,mu) events at sqrt(s) = 1.96 TeV. The data were collected with the DO detector from an integrated luminosity of 162 pb^{-1} delivered by the Fermilab Tevatron Collider. The cross section times branching fraction for p-pbar -> W(gamma) + X -> l nu gamma + X with E_T^{gamma} > 8 GeV and Delta R_{l gamma} > 0.7 is 14.8 +/- 1.6 (stat) +/- 1.0 (syst) +/- 1.0 (lum) pb. The one-dimensional 95% confidence level limits on anomalous couplings are -0.88 < Delta kappa_{gamma} < 0.96 and -0.20 < lambda_{gamma} < 0.20.Comment: Submitted to Phys. Rev. D Rapid Communication

Measurement of the ttbar Production Cross Section in ppbar Collisions at sqrt{s} = 1.96 TeV using Kinematic Characteristics of Lepton + Jets Events

We present a measurement of the top quark pair ttbar production cross section in ppbar collisions at a center-of-mass energy of 1.96 TeV using 230 pb**{-1} of data collected by the DO detector at the Fermilab Tevatron Collider. We select events with one charged lepton (electron or muon), large missing transverse energy, and at least four jets, and extract the ttbar content of the sample based on the kinematic characteristics of the events. For a top quark mass of 175 GeV, we measure sigma(ttbar) = 6.7 {+1.4-1.3} (stat) {+1.6- 1.1} (syst) +/-0.4 (lumi) pb, in good agreement with the standard model prediction.Comment: submitted to Phys.Rev.Let

Measurement of the ttbar Production Cross Section in ppbar Collisions at sqrt(s)=1.96 TeV using Lepton + Jets Events with Lifetime b-tagging

We present a measurement of the top quark pair ($t\bar{t}$) production cross section ($\sigma_{t\bar{t}}$) in $p\bar{p}$ collisions at $\sqrt{s}=1.96$ TeV using 230 pb$^{-1}$ of data collected by the D0 experiment at the Fermilab Tevatron Collider. We select events with one charged lepton (electron or muon), missing transverse energy, and jets in the final state. We employ lifetime-based b-jet identification techniques to further enhance the $t\bar{t}$ purity of the selected sample. For a top quark mass of 175 GeV, we measure $\sigma_{t\bar{t}}=8.6^{+1.6}_{-1.5}(stat.+syst.)\pm 0.6(lumi.)$ pb, in agreement with the standard model expectation.Comment: 7 pages, 2 figures, 3 tables Submitted to Phys.Rev.Let

Search for W' bosons decaying to an electron and a neutrino with the D0 detector

This Letter describes the search for a new heavy charged gauge boson W' decaying into an electron and a neutrino. The data were collected with the D0 detector at the Fermilab Tevatron proton-antiproton Collider at a center-of-mass energy of 1.96 TeV, and correspond to an integrated luminosity of about 1 inverse femtobarn. Lacking any significant excess in the data in comparison with known processes, an upper limit is set on the production cross section times branching fraction, and a W' boson with mass below 1.00 TeV can be excluded at the 95% C.L., assuming standard-model-like couplings to fermions. This result significantly improves upon previous limits, and is the most stringent to date.Comment: submitted to Phys. Rev. Let

Search for a scalar or vector particle decaying into Zgamma in ppbar collisions at sqrt(s) = 1.96 TeV

We present a search for a narrow scalar or vector resonance decaying into Zgamma with a subsequent Z decay into a pair of electrons or muons. The data for this search were collected with the D0 detector at the Fermilab Tevatron ppbar collider at a center of mass energy sqrt(s) = 1.96 TeV. Using 1.1 (1.0) fb-1 of data, we observe 49 (50) candidate events in the electron (muon) channel, in good agreement with the standard model prediction. From the combination of both channels, we derive 95% C.L. upper limits on the cross section times branching fraction (sigma x B) into Zgamma. These limits range from 0.19 (0.20) pb for a scalar (vector) resonance mass of 600 GeV/c^2 to 2.5 (3.1) pb for a mass of 140 GeV/c^2.Comment: Published by Phys. Lett.

Measurement of the ratios of the Z/G* + >= n jet production cross sections to the total inclusive Z/G* cross section in ppbar collisions at sqrt(s) = 1.96 TeV

We present a study of events with Z bosons and jets produced at the Fermilab Tevatron Collider in ppbar collisions at a center of mass energy of 1.96 TeV. The data sample consists of nearly 14,000 Z/G* -> e+e- candidates corresponding to the integrated luminosity of 0.4 fb-1 collected using the D0 detector. Ratios of the Z/G* + >= n jet cross sections to the total inclusive Z/G* cross section have been measured for n = 1 to 4 jet events. Our measurements are found to be in good agreement with a next-to-leading order QCD calculation and with a tree-level QCD prediction with parton shower simulation and hadronization.Comment: 7 pages, 2 figures, slightly modified, submitted to Phys. Lett.

Measurement of the Isolated Photon Cross Section in p-pbar Collisions at sqrt{s}=1.96 TeV

The cross section for the inclusive production of isolated photons has been measured in p anti-p collisions at sqrt{s}=1.96 TeV with the D0 detector at the Fermilab Tevatron Collider. The photons span transverse momenta 23 to 300 GeV and have pseudorapidity |eta|<0.9. The cross section is compared with the results from two next-to-leading order perturbative QCD calculations. The theoretical predictions agree with the measurement within uncertainties.Comment: 7 pages, 5 figures, submitted to Phys.Lett.