The dependence ofNKRversus KR: the initial, thermal, volumetric recombination and screening effect on the efficiency of collected charges on the calibration of si HDR1000 plus well chambers with192Ir HDR sources.

By using the statistical techniques of the ANOVA means test and regression, it was found that theNKRcalibration factor of Standard Imaging (SI) model HDR 1000 plus chambers presents a quadratic dependence with the Reference air kerma rateKR(from 6.9 mGy h-1to 43.9 mGy h-1). In order to understand and correct this dependency one model is presented for total recombination:ks=I300I150=1+kini+kd+kvol·I300+kscreen·I3002,wherekiniis the initial recombination,kvolthe thermal diffusion recombination,kvolthe volumetric recombination andkscreenthe screening for the currents/charges collected at the potential differences of 300 and 150 V. In conclusion, the total recombinationksis composed by onekiniwith a constant contribution of 0.019%, onekdcontribution of 0.017%, onekvol·I300contribution from 0.022% to 0.138%, and thekscreen·I3002effects from 0.002% to 0.09% in the range ofK̇Rrate above. However, when this model forksis applied to try to correct the quadratic dependence of theNKRversusKR,explicitly there is no improvement in the variation range of 0.5% of theNKRversusKR.Nonetheless, it allows to obtainNKRvalues consistent with auc ≤ 0.7%, which is less than 1.25% reported in the literature by ADCLs or SSDLs.

Biochemical characterization of pathogenic bacterial species using Raman spectroscopy and discrimination model based on selected spectral features.

This study aimed to evaluate the differences in the Raman spectra of nine clinical species of bacteria isolated from infections (three Gram-positive and six Gram-negative species), correlating the spectra with the chemical composition of each species and to develop a classification model through discriminant analysis to categorize each bacterial strain using the peaks with the most significant differences. Bacteria were cultured in Mueller Hinton agar and a sample of biomass was harvested and placed in an aluminum sample holder. A total of 475 spectra from 115 different strains were obtained through a dispersive Raman spectrometer (830 nm) with exposure time of 50 s. The intensities of the peaks were evaluated by one-way analysis of variance (ANOVA) and the peaks with significant differences were related to the differences in the biochemical composition of the strains. Discriminant analysis based on quadratic distance applied to the peaks with the most significant differences and partial least squares applied to the whole spectrum showed 89.5% and 90.1% of global accuracy, respectively, for classification of the spectra in all the groups. Raman spectroscopy could be a promising technique to identify spectral differences related to the biochemical content of pathogenic microorganisms and to provide a faster diagnosis of infectious diseases.

Spray Drying of Blueberry Juice-Maltodextrin Mixtures: Evaluation of Processing Conditions on Content of Resveratrol.

Resveratrol is an antioxidant abundant in red fruits, and one of the most powerful inhibiting reactive oxygen species (ROS) and oxidative stress (OS) produced by human metabolism. The effect of the spray drying processing conditions of blueberry juice (BJ) and maltodextrin (MX) mixtures was studied on content and retention of resveratrol. Quantitatively, analysis of variance (ANOVA) showed that concentration of MX was the main variable influencing content of resveratrol. Response surface plots (RSP) confirmed the application limits of maltodextrins based on their molecular weight, where low molecular weight MXs showed a better performance as carrying agents. After qualitatively comparing results for resveratrol against those reported for a larger antioxidant molecule (quercetin 3-D-galactoside), it was observed a higher influence of the number of active sites available for the chemical interactions, instead of stearic hindrance effects.