Universidad Iberoamericana Ciudad de México

About: Universidad Iberoamericana Ciudad de México is a education organization based out in Mexico City, Mexico. It is known for research contribution in the topics: Large Hadron Collider & Standard Model. The organization has 2259 authors who have published 3981 publications receiving 109298 citations.

Impact of environmental conditions and process modifications on microbial diversity, fermentation efficiency and chemical profile during the fermentation of Mezcal in Oaxaca

Abstract: Mezcal, a distilled alcoholic beverage derived from cooked agave plants, is manufactured traditionally on a small scale where raw materials and production practices differ noticeably between production regions, localities and even factories resulting in a set of highly distinctive products. The present study aimed to draw a comprehensive picture of the mezcal production in Oaxaca State, relating the microbial consortia with the chemical compounds detected during mezcal fermentation, and to elucidate the impact of process modifications made in order to improve fermentation performance. In two mezcal distilleries, fermentation processes were monitored in two consecutive years. Isolated yeasts (553) and bacteria (527) were identified combining traditional and molecular techniques, detecting up to 21 different yeast species and 27 different bacterial species during a single process. Fermentation kinetics and volatile compound generation varied strongly between the studied processes. A highly diverse microbiota associated to these traditional alcoholic fermentations was detected wherein several yeast species and numerous bacterial groups built up the microbial consortia. Modifications introduced between two production seasons showed a clear impact on microbial diversity. The employment of wild inoculums increased alcoholic fermentation efficiency, nevertheless, prominent changes in the volatile compound profile should be taken into account.

Applications of soluble dietary fibers in beverages

Abstract: In this work the importance of soluble dietary fibers in the human diet is discussed. Traditional and new sources of soluble dietary fiber are mentioned, an...

Gas Permeation Properties of Soluble Aromatic Polyimides Based on 4-Fluoro-4,4'-Diaminotriphenylmethane

Abstract: A series of new organic polyimides were synthesized from 4-fluoro-4'4"-diaminotriphenylmethane and four different aromatic dianhydrides through a one-step, high-temperature, direct polycondensation in m-cresol at 180-200 °C, resulting in the formation of high-molecular-weight polyimides (inherent viscosities ~ 1.0-1.3 dL/g). All the resulting polyimides exhibited good thermal stability with initial decomposition temperatures above 434 °C, glass-transition temperatures between 285 and 316 °C, and good solubility in polar aprotic solvents. Wide-angle X-ray scattering data indicated that the polyimides were amorphous. Dense membranes were prepared by solution casting and solvent evaporation to evaluate their gas transport properties (permeability, diffusivity, and solubility coefficients) toward pure hydrogen, helium, oxygen, nitrogen, methane, and carbon dioxide gases. In general, the gas permeability was increased as both the fractional free volume and d-spacing were also increased. A good combination of permeability and selectivity was promoted efficiently by the bulky hexafluoroisopropylidene and 4-fluoro-phenyl groups introduced into the polyimides. The results indicate that the gas transport properties of these films depend on both the structure of the anhydride moiety, which controls the intrinsic intramolecular rigidity, and the 4-fluoro-phenyl pendant group, which disrupts the intermolecular packing.

Direct Top-Quark Width Measurement at CDF

Abstract: We present a measurement of the top-quark width using $t\bar{t}$ events produced in $p\bar{p}$ collisions at Fermilab's Tevatron collider and collected by the CDF II detector. In the mode where the top quark decays to a $W$ boson and a bottom quark, we select events in which one $W$ decays leptonically and the other hadronically~(lepton + jets channel) . From a data sample corresponding to 4.3~fb$^{-1}$ of integrated luminosity, we identify 756 candidate events. The top-quark mass and the mass of $W$ boson that decays hadronically are reconstructed for each event and compared with templates of different top-quark widths~($\Gamma_t$) and deviations from nominal jet energy scale~($\Delta_{JES}$) to perform a simultaneous fit for both parameters, where $\Delta_{JES}$ is used for the {\it in situ} calibration of the jet energy scale. By applying a Feldman-Cousins approach, we establish an upper limit at 95$\%$ confidence level~(CL) of $\Gamma_t <$ 7.6 GeV and a two-sided 68$\%$ CL interval of 0.3 GeV $< \Gamma_t <$ 4.4 GeV for a top-quark mass of 172.5 GeV$/c^2$, which are consistant with the standard model prediction. This is the first direct measurement of $\Gamma_t$ to set a lower limit with 68$\%$ CL.