Feasibility of DS-GF AAS for the determination of metallic impurities in raw material for polymers production.

A new procedure is proposed for the determination of metal contaminants (Cr, Fe, Mg, Mn, Na and Ni) in polymeric diphenylmethane diisocyanate (PMDI), a raw material used to produce polyurethane polymers. The feasibility of using Zeeman-effect background correction graphite furnace atomic absorption spectrometry (GF AAS) and direct sampling (DS) was evaluated. Calibration using aqueous standard solutions was feasible and chemical modifiers as well as reference materials for this purpose were unnecessary. Relatively high sample masses (up to 23 mg) were used allowing very low limits of detection ranging from 0.06 ng g-1 to 1 ng g-1 (Fe and Mg) up to 3  ng g-1 (Ni), with relative standard deviation lower than 15%. The following parameters were evaluated: pyrolysis and atomization temperatures , sample mass, as well as the use of low sensitivity conditions (Zeeman effect background correction magnetic field strength adjustment and the use of a secondary wavelength for Fe and Na determinations, respectively). Results were compared with those obtained by microwave-assisted digestion and microwave-induced combustion with subsequent analytes determination by inductively coupled plasma optical emission spectrometry (ICP-OES) and by inductively coupled plasma mass spectrometry (ICP-MS). No significant difference was observed between the results obtained by DS-GF AAS, ICP-MS and ICP-OES after both digestion systems. The proposed DS-GF AAS method allowed the determination of six elements in PMDI (which is considered as a complex matrix) with limits of detection lower than those achieved by other methods. This new procedure can be used as quality control of polyurethanes industry for ultra-trace inorganic impurities.

Gas hydrate dissociation linked to contemporary ocean warming in the southern hemisphere.

Ocean warming related to climate change has been proposed to cause the dissociation of gas hydrate deposits and methane leakage on the seafloor. This process occurs in places where the edge of the gas hydrate stability zone in sediments meets the overlying warmer oceans in upper slope settings. Here we present new evidence based on the analysis of a large multi-disciplinary and multi-scale dataset from such a location in the western South Atlantic, which records massive gas release to the ocean. The results provide a unique opportunity to examine ocean-hydrate interactions over millennial and decadal scales, and the first evidence from the southern hemisphere for the effects of contemporary ocean warming on gas hydrate stability. Widespread hydrate dissociation results in a highly focused advective methane flux that is not fully accessible to anaerobic oxidation, challenging the assumption that it is mostly consumed by sulfate reduction before reaching the seafloor.

Transcutaneous Electrical Stimulation of PC5 and PC6 Acupoints Modulates Autonomic Balance in Heart Transplant Patients: A Pilot Study.

The increased resting heart rate (HR) in heart transplant patients is associated with enhanced metabolic demand, the potential for fatigue, and lower quality of life. In the present study, we hypothesized that transcutaneous electrical acupoint stimulation (TEAS) could modulate autonomic balance and reduce resting HR in these patients. A single-arm clinical trial was conducted with patients aged > 18 years, at ambulatorial accompaniment after heart transplantation, who were submitted to a single TEAS (40 minutes at pericardium channel acupoints PC5 and PC6). The arterial blood pressure and RR interval were recorded from 20 minutes before to 20 minutes after TEAS. The RR intervals were used to calculate HR variability (HRV) and the sympathovagal index. Linear mixed models were used for comparing variables before, during, and after TEAS. The significance level was set as P < 0.05. TEAS acutely improved HRV in transplant patients and enhanced the sympathovagal index during its application. Significant increases in systolic and diastolic blood pressure and mean arterial pressure were observed at recovery, such as a slight, but significant, decrease in HR. In conclusion, TEAS at PC5 and PC6 acutely modulates HRV and hemodynamics in transplant patients.

Influence of hydraulic loading rate and recirculation on oxygen transfer in a vertical flow constructed wetland.

The oxygen transfer rate (OTR) has a significant impact on the design and operation of vertical flow constructed wetlands (VFCWs) intended for organic matter removal and nitrification. Despite its key role, the information on real oxygen input in VFCWs is limited, being usually estimated by mass balance (stoichiometry), through which is calculated only the oxygen consumption rate (OCR). In this study, for the first time, the gas tracer method was applied to evaluate the oxygen transfer capacity of a real-scale VFCW (24.5 m2) applied to the treatment of domestic wastewater. Propane was used as tracer. The OCR and the OTR were evaluated in VFCW under hydraulic loading rates (HLR) of 60, 90, and 120 mm d-1 corresponding to recirculation rations of 0%, 50%, and 100%. The OTR in standard conditions (20 °C) ranged from 120 to 176 g O2 m-2 d-1. The highest OTR was found for the lowest HLR. For the operating conditions tested, the OTR obtained with gas tracer were higher than the OCR calculated by stoichiometry in VFCW, which ranged from 20.6 to 27.8 g O2 m-2 d-1. Besides, the OTR were sufficient to satisfy the VFCW oxygen demand for organic matter removal and nitrification. These results show that the gas tracer method for OTR determination may allow advances on the understanding of treatment processes and on the design of new VFCWs since its treatment performance requires aerobic conditions.

Acupuncture for the Treatment of Cardiovascular Diseases: A Systematic Review.

Acupuncture, for the westerns countries, is an innovative and low-cost therapy for treatment and prevention of cardiovascular diseases (CVDs). However, most of its effects and mechanisms are poorly understood. Thus, the objective of this work was to systematically review the literature regarding the clinical effects of acupuncture for the treatment and prevention of CVDs. A search for papers published in English or Portuguese in the past 20 years was conducted at PubMed, SciELO, and PEDro databases. Clinical trials conducted on the effects of acupuncture were included in this review. Two reviewers extracted the data independently from the remaining 17 articles after screening. The most used acupoint was PC6 (10 studies, 64.7%), followed by ST36 (6 studies, 35.3%) and auricular acupoints (4 studies, 23.5%). Among the clinical applications, hypertension was the most studied CVD, with acupuncture being the most reported method among the studies (70.6%). Only three articles reported no benefit in the treatment of CVDs for the methodology used. We conclude that although several studies indicated an improvement in the response of the cardiovascular system in CVDs by acupuncture, electroacupuncture, or electrostimulation treatment, the heterogeneity of the studies does not allow a standardization of its application for each specific disease, making further studies necessary for its use to become a reality.

Evaluation of different samplers and storage temperature effect on the methane carbon stable isotope analysis.

The present work evaluates the efficiency of some low-cost sampler container for a reliable carbon stable isotope analysis of methane. The procedure efficiency was evaluated for five containers, through 91 days, under two storage temperatures (4 °C and 25 °C) and the results are compared against a reference sampler by using univariate and multivariate statistical methods. Based on the univariate (ANOVA and comparison statistical methods) and multivariate (PCA and HCA) statistical methods, it was identified that (i) the isotopic value changes with time and, in this way, must be taken in account when choosing the appropriate sampler and (ii) the lower temperature reduces the isotopic fractionation process and is preferable for the gas sample storage. Among the storage systems, two options were found to be statistically equivalent to the reference container (IsoJar) for a time horizon of 91 days. We found that the exetainer (4 °C and 25 °C) storage systems are statistically equivalent to the reference container IsoJar and, in this way, it could be an alternative for the methane isotopic studies.

The Brazilian developments on the Regional Atmospheric Modeling System (BRAMS 5.2): an integrated environmental model tuned for tropical areas.

We present a new version of the Brazilian developments on the Regional Atmospheric Modeling System where different previous versions for weather, chemistry and carbon cycle were unified in a single integrated software system. The new version also has a new set of state-of-the-art physical parameterizations and greater computational parallel and memory usage efficiency. Together with the description of the main features are examples of the quality of the transport scheme for scalars, radiative fluxes on surface and model simulation of rainfall systems over South America in different spatial resolutions using a scale-aware convective parameterization. Besides, the simulation of the diurnal cycle of the convection and carbon dioxide concentration over the Amazon Basin, as well as carbon dioxide fluxes from biogenic processes over a large portion of South America are shown. Atmospheric chemistry examples present model performance in simulating near-surface carbon monoxide and ozone in Amazon Basin and Rio de Janeiro megacity. For tracer transport and dispersion, it is demonstrated the model capabilities to simulate the volcanic ash 3-d redistribution associated with the eruption of a Chilean volcano. Then, the gain of computational efficiency is described with some details. BRAMS has been applied for research and operational forecasting mainly in South America. Model results from the operational weather forecast of BRAMS on 5 km grid spacing in the Center for Weather Forecasting and Climate Studies, INPE/Brazil, since 2013 are used to quantify the model skill of near surface variables and rainfall. The scores show the reliability of BRAMS for the tropical and subtropical areas of South America. Requirements for keeping this modeling system competitive regarding on its functionalities and skills are discussed. At last, we highlight the relevant contribution of this work on the building up of a South American community of model developers.

Resistência à fratura de dentes reforçados com pinos pré-fabricados utilizando diferentes agentes cimentantes / Resistance to fracture of teeth reinforced with different pre-fabricated posts, using different cementing agents

O estudo comparou in vitro a resistência à fratura em dentes tratados endodonticamente reforçados com pinos intra-radiculares pré-fabricados, utilizando diferentes agentes cimentantes. Cinquenta dentes humanos permanentes unirradiculares obturados, foram divididos em 5 grupos: G I-controle (sem pino); G II- pino de fibra de carbono + cimento Rely X; G III- pino de fibra de carbono + cimento Enforce; G IV- pino de fibra de vidro + cimento Rely X; G V- pino de fibra de vidro + cimento En-force. Após cimentação dos pinos e restauração coronal, as raízes foram incluídas em resina acrílica quimicamente ativada e submetidos à carga de compressão em uma Máquina Universal de Ensaios (Instron 5582). Os dados obtidos foram analisados estatisticamente pelos testes Exato de Fisher e o teste F (ANOVA), a um nível de signifcância de 5,0%, os quais demonstraram que em relação ao local da interface no grupo total, a maioria (67,5%) das amostras teve fratura na interface dente/agente cimentante; destacou-se também que a freqüência de fraturas no dente/agente cimentante variou de 4 (grupo V) a 10 (grupo III), diferenças estas significante entre os grupos. Concluiu-se que o uso dos pinos pré-fabricados não proporcionou aumento na resistência dos dentes tratados endodonticamente; o pino de fibra de vidro em associação ao sistema Enforce mostrou-se superior na resistência à fratura, sendo estatisticamente signifcante quando comparado ao grupo Enforce / pino de fibra de carbono; em relação à resistência de união, o maior comprometimento se deu na interface agente cimentante/dente quando comparada ao agente cimentante/pino.

The study compared in vitro the resistance to fracture of teeth endodontically treated reinforced with prefabricated intra-radicular posts, cemented with diferent cementation agents. Fifty permanents human teeth which had only one root was filled and divided in five groups: G I- control (without pin); G II carbon-fiber post + Rely X cement; G III carbon-fiber post + Enforce cement; G- IV fiber core post + Rely-X cement; G-V f- ber core post + Enforce cement. After cementation of this posts and coronal restoration, the root was included in self-activated acrylic resin and was submited to compressive axial loading in a Universal Testing Machine (Instron 5582). The results were statistically analyzed by Exato de Fisher test and test F (ANOVA), with 5,0 % signifcance, which demonstrated that in relation to the interface place in the total group, the majority (67,5%) of the samples had fracture on interface tooth/cementation agent ; the frequency of fractures on teeth/cementation agent varied from 4 (group V) to 10 (group III), and these diferences were significant among the groups. It was concluded that the use of prefabricated intra radicular posts couldn´t intensify the resistance of endodontically treated teeth; fiber core post associated to Enforce cement was more resistant to fracture, and statistically significant than carbon-fiber post and Enforce cement group. About bond strength the interface cement agent/teeth was less resistant than cement agent/pin.