3,015 research outputs found
Rapid spectrofluorometric screening of poly-hydroxyalkanoate-producing bacteria from microbial mats
Microbial mat ecosystems are characterized by both seasonal and diel fluctuations in several physicochemical variables, so that resident microorganisms must frequently adapt to the changing conditions of their environment. It has been pointed out that, under stress conditions, bacterial cells with higher contents of poly-hydroxyalkanoates (PHA) survive longer than those with lower PHA content. In the present study, PHA-producing strains from Ebro Delta microbial mats were selected using the Nile red dying technique and the relative accumulation of PHA was monitored during further laboratory cultivation. The number of heterotrophic isolates in trypticase soy agar (TSA) was ca. 107 colony-forming units/g microbial mat. Of these, 100 randomly chosen colonies were replicated on mineral salt agar limited in nitrogen, and Nile red was added to the medium to detect PHA. Orange fluorescence, produced upon binding of the dye to polymer granules in the cell, was detected in approximately 10% of the replicated heterotrophic isolates. The kinetics of PHA accumulation in Pseudomonas putida, and P. oleovorans were compared with those of several of the environmental isolates spectrofluorometry. PHA accumulation, measured as relative fluorescence intensity, resulted in a steady-state concentration after 48 h of incubation in all strains assayed. At 72 h, the maximum fluorescence intensity of each strain incubated with glucose and fructose was usually similar. MAT-28 strain accumulated more PHA than the other isolates. The results show that data obtained from environmental isolates can highly improve studies based on modeling-simulation programs, and that microbial mats constitute an excellent source for the isolation of PHA-producing strains with industrial applications. [Int Microbiol 2006; 9(2):95-102
Optical properties of polycrystalline Cd(1-x)Mn(x)Te
Bulk polycrystalline cadmium manganese telluride, Cd(l-x)Mn(x)Te, was manufactured in several compositions by a synthesis process. The structure of the obtained compounds was the characteristic zinc-blende polycrystalline pattern being the grain size lOOj=20 nm. These materials are manufactured to replace single-crystal compounds in some magneto-optical devices. The cut-off wavelength and the Verdet constant are the same as the single-crystals with identical composition. A polarized laser beam, after having passed through a sample of 0.76 mm thickness, was depolarized less than 2.5%, and 90% of its energy was spread into a 2º cone. Scattering of light is produced because of the polycrystalline structure of these ompounds. Some scattering diagrams, due to the diffraction and Mie scattering in the polycrystalline grains are shown
Electromagnetic Form Factors and Charge Radii of Pseudoscalar and Scalar Mesons: A Comprehensive Contact Interaction Analysis
We carry out a comprehensive survey of electromagnetic form factors of all
light, heavy and heavy-light ground-state pseudoscalar and scalar mesons. Our
analysis is based upon a Schwinger-Dyson equations treatment of a vector
vector contact interaction. It incorporates confinement and ensures
axial vector and vector Ward-Takahashi identities are satisfied along with the
corresponding corollaries such as the Goldberger-Treiman relations. The
algebraic simplicity of the model allows us to compute the form factors at
arbitrarily large virtualities of the probing photon momentum squared with
relative ease. Wherever possible and insightful, we compare our results for the
electromagnetic form factors and the charge radii with those obtained earlier
through Schwinger-Dyson equations, lattice and with experimental observations
available. We also comment on the scope and shortcomings of the model.Comment: 13 pages, 13 figure
Incidence of complications in breast reconstruction with autologous tissue in a third level hospital
Background: The objective of this study is to analyze the incidence of complications after breast reconstruction with pedicled or free flaps at the hospital general de Mexico "Dr. Eduardo Liceaga”.
Methods: A retrospective, single-center study, including 44 female patients, who underwent immediate or delayed breast reconstruction after breast cancer, between 2019 and 2020, and had at least a 2-year follow up, evaluating the association between patient risk factors (age, history of radiotherapy, presence of overweight or obesity and immediate or delayed reconstruction) with the presence of complications such as seroma, hematoma, wound infection or wound dehiscence. We analyzed data with SPSS software, v23.0.
Results: There was no statistically significant difference for the presence of complications associated with risk factors studied.
Conclusions: We need more prospective, multicenter studies, including larger sample and strict follow up of patients
Characterization and Di erentiation of Spanish Vinegars from Jerez and Condado de Huelva Protected Designations of Origin
Thirty one Jerez vinegar samples and 33 Huelva vinegar samples were analyzed for
polyphenolic and volatile compound content in order to characterize them and attempt to di erentiate
them. Sixteen polyphenolic compounds were quantified by means of ultraperformance liquid
chromatography method with diode array detection (UPLC–DAD), and 37 volatile compounds
were studied by means of stir bar sorptive extraction–gas chromatography–mass spectrometry
(SBSE–GC–MS). Spectrophotometric CIELab parameters were also measured for all the samples.
The results obtained from the statistical multivariate treatment of the data evidenced a clear di erence
between vinegars from the two geographical indications with regard to their polyphenolic content,
with Jerez vinegars exhibiting a greater phenolic content. Di erentiation by the volatile compound
content was, however, not so evident. Nevertheless, a considerable di erentiation between the two
groups of vinegars based on their volatile fraction was achieved. This may bring to light the grape
varieties and geographical factors that have a clear influence on such di erences
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