Autonomic impairment of patients in coma with different Glasgow coma score assessed with heart rate variability

Primary objective: The objective of this study is to assess the functional state of the autonomic nervous system in healthy individuals and in individuals in coma using measures of heart rate variability (HRV) and to evaluate its efficiency in predicting mortality. Design and Methods: Retrospective group comparison study of patients in coma classified into two subgroups, according to their Glasgow coma score, with a healthy control group. HRV indices were calculated from 7 min of artefact-free electrocardiograms using the Hilbert–Huang method in the spectral range 0.02–0.6 Hz. A special procedure was applied to avoid confounding factors. Stepwise multiple regression logistic analysis (SMLRA) and ROC analysis evaluated predictions. Results: Progressive reduction of HRV was confirmed and was associated with deepening of coma and a mortality score model that included three spectral HRV indices of absolute power values of very low, low and very high frequency bands (0.4-0.6 Hz). The SMLRA model showed sensitivity of 95.65%, specificity of 95.83%, positive predictive value of 95.65%, and overall efficiency of 95.74%. Conclusions: HRV is a reliable method to assess the integrity of the neural control of the caudal brainstem centres on the hearts of patients in coma and to predict patient mortality

Measure of Customer Satisfaction in the Residential Electricity Distribution Service Using Structural Equation Modeling

The main objective of this study is to apply structural equation modeling with partial least squares, and based on covariance, to assess the satisfaction of residential electricity consumers. The methodology used compares the results of both structural equation models to indicate the model that best fits the problem of measuring the satisfaction of residential consumers with electricity concessionaires and licensees. The sample used in the survey contained questionnaire responses from 86,175 individuals considering the period from 2014 to 2018. The constructs evaluated were satisfaction, quality, value, loyalty, and trust. A confidence interval analysis shows that all weights are significant, demonstrating the importance of all the indicators that represent the constructs. The trust, quality, and value constructs can explain 74.4% of the satisfaction construct variability, so this relationship’s explanatory capacity is considered substantial. Finally, the evaluation of the performance of the service provided by the electric energy concessionaires/licensees, measured by customer satisfaction, allows for the continuous improvement of services, and meeting, even if minimally, the expectations of its consumers

A 2.8 Å Fe–Fe Separation in the Fe₂^III/IV Intermediate, X, from <i>Escherichia coli</i> Ribonucleotide Reductase

A class Ia ribonucleotide reductase (RNR) employs a μ-oxo-Fe₂^III/III/tyrosyl radical cofactor in its β subunit to oxidize a cysteine residue ∼35 Å away in its α subunit; the resultant cysteine radical initiates substrate reduction. During self-assembly of the <i>Escherichia coli</i> RNR-β cofactor, reaction of the protein’s Fe₂^II/II complex with O₂ results in accumulation of an Fe₂^III/IV cluster, termed <b>X</b>, which oxidizes the adjacent tyrosine (Y₁₂₂) to the radical (Y₁₂₂^•) as the cluster is converted to the μ-oxo-Fe₂^III/III product. As the first high-valent non-heme-iron enzyme complex to be identified and the key activating intermediate of class Ia RNRs, <b>X</b> has been the focus of intensive efforts to determine its structure. Initial characterization by extended X-ray absorption fine structure (EXAFS) spectroscopy yielded a Fe–Fe separation (<i>d</i>_Fe–Fe) of 2.5 Å, which was interpreted to imply the presence of three single-atom bridges (O^2–, HO^–, and/or μ-1,1-carboxylates). This short distance has been irreconcilable with computational and synthetic models, which all have <i>d</i>_Fe–Fe ≥ 2.7 Å. To resolve this conundrum, we revisited the EXAFS characterization of <b>X</b>. Assuming that samples containing increased concentrations of the intermediate would yield EXAFS data of improved quality, we applied our recently developed method of generating O₂ <i>in situ</i> from chlorite using the enzyme chlorite dismutase to prepare <b>X</b> at ∼2.0 mM, more than 2.5 times the concentration realized in the previous EXAFS study. The measured <i>d</i>_Fe–Fe = 2.78 Å is fully consistent with computational models containing a (μ-oxo)₂-Fe₂^III/IV core. Correction of the <i>d</i>_Fe–Fe brings the experimental data and computational models into full conformity and informs analysis of the mechanism by which <b>X</b> generates Y₁₂₂^•

Optimization and Recovery of a Pressure Swing Adsorption Process for the Purification and Production of Bioethanol

Today, there are new technologies to produce bioethanol: one of them is the Pressure Swing Adsorption (PSA) process. This process has displaced other separation technologies due to the use of natural adsorbents and its methodology to obtain high purities with a lower energy cost. The aim of this work focuses on the optimization of the PSA process (experimental case) to obtain a higher recovery and production of bioethanol using lower energy consumption. The results are favorable since the energy cost is reduced to a range of 60% and 62%, obtaining purities above 99% wt of ethanol and recovery between 75% and 77.41%. The bioethanol produced and purified in the different scenarios meets international standards to be used as a fuel or oxygenating additive