Oxygen reduction reaction catalyzed by epsilon-MnO2: Influence of the crystalline structure on the reaction mechanism

The oxygen reduction reaction (ORR) was studied in KOH electrolyte on carbon supported epsilon-manganese dioxide (epsilon-MnO2/C). The epsilon-MnO2/C catalyst was prepared via thermal decomposition of manganese nitrate and carbon powder (Vulcan XC-72) mixtures. X-ray powder diffraction (XRD) measurements were performed in order to determine the crystalline structure of the resulting composite, while energy dispersive X-ray analysis (EDX) was used to evaluate the chemical composition of the synthesized material. The electrochemical studies were conducted using cyclic voltammetry (CV) and quasi-steady state polarization measurements carried out with an ultra thin layer rotating ring/disk electrode (RRDE) configuration. The electrocatalytic results obtained for 20% (w/w) Pt/C (E-TEK Inc., USA) and alpha-MnO2/C for the ORR, considered as one of the most active manganese oxide based catalyst for the ORR in alkaline media, were included for comparison. The RRDE results revealed that the ORR on the MnO2 catalysts proceeds preferentially through the complete 4e(-) reduction pathway via a 2 plus 2e(-) reduction process involving hydrogen peroxide as an intermediate. A benchmark close to the performance of 20% (w/w) Pt/C (E-TEK Inc., USA) was observed for the epsilon-MnO2/C material in the kinetic control region, superior to the performance of alpha-MnO2/C, but a higher amount of HO2- was obtained when epsilon-MnO2/C was used as catalyst. The higher production of hydrogen peroxide on epsilon-MnO2/C was related to the presence of structural defects, typical of this oxide, while the better catalytic performance in the kinetic control region compared to alpha-MnO2/C was related with the higher electrochemical activity for the proton insertion kinetics, which is a structure sensitive process. (C) 2012 Elsevier Ltd. All rights reserved.

Oxygen reduction reaction on a Pt/carbon fuel cell catalyst in the presence of trace quantities of ammonium ions: An RRDE study

The effect of trace quantities of ammonia on oxygen reduction reaction (ORR) on carbon-supported platinum catalysts in perchloric acid solutions is assessed using rotating ring disk electrode (RRDE) technique. The study demonstrates that ammonia has detrimental effects on ORR. The most significant effect takes place in the potential region above 0.7 V vs RHE. The effect is explained by the electrochemical oxidation of ammonia, which blocks Pt active sites and increases the formation of H2O2. This leads to losses in the disk currents and increments in the ring currents. The apparent losses in ORR currents may occur in two ways, namely, through the blocking of the active sites for ORR as well as by generating a small anodic current, which is believed to have a lower contribution. In addition, a detrimental effect of sodium cations in the potential range below 0.75 V vs RHE was demonstrated. This effect is most likely due to the co-adsorption of sodium cations and perchlorate anions on the Pt surface. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Mechanistic changes observed in heavy water for nitrate reduction reaction on palladium-modified Pt(hkl) electrodes

Reduction of nitrate on palladium-modified platinum single-crystal electrodes has been investigated both voltammetrically and spectroscopically in acidic media (pH = 1). Results obtained in H2O and D2O solvents are compared for the three crystallographic orientations. FTIR and differential electrochemical mass spectrometry (DEMS) results clearly indicate that the isotopic substitution of the solvent has a large effect in the mechanism of the reaction, changing the nature of the detected products. For Pt(111)/Pd and Pt(100)/Pd, N2O is detected as the main product of nitrate reduction when D2O is used as solvent, while no N2O is detected when the reaction is performed in H2O. For Pt(110)/Pd, N2O is detected in both solvents, although the use of D2O clearly favours the preferential formation of this product. The magnitude of voltammetric currents is also affected by the nature of the solvent. This has been analysed considering, in addition to the different product distribution, the existence of different transport numbers and optical constants of the solvent.

Anti-inflammatory effect of Spiranthera odoratissima A. St.-Hil. leaves involves reduction of TNF-alpha

Spiranthera odoratissima A. St.-Hil., 'manaca', is a medicinal species used in Brazil, especially in central region, for the treatment of several diseases such as pain and inflammation. In this study, the methanol/aqueous phase of the ethanol extract of the leaves of 'manaca' (MAP), at the doses of 50, 150 and 500 mg/kg was used to evaluate the anti-inflammatory and/or antinociceptive effects and the possible anti-inflammatory mechanism. The antinociceptive and anti-inflammatory activities of MAP were assessed using formalin test, carrageenan-induced paw oedema. The myeloperoxidase activity, capillary permeability, leukocyte migration and tumour necrosis factor alpha (TNF-alpha) levels were evaluated in pleural exudate. The MAP reduced the licking time only in the later phase of formalin test, and showed anti-inflammatory activity by reducing the paw oedema, migration cell, myeloperoxidase activity, capillary permeability and TNF-alpha levels. In conclusion, we confirmed the inflammatory activity of MAP and affirm that this effect involves the reduction of TNF-alpha level.

Performance and selectivity of PtxSn/C electro-catalysts for ethanol oxidation prepared by reduction with different formic acid concentrations

Carbon supported Pt-Sn catalysts were prepared by reduction of Pt and Sn precursors with formic acid and characterized in terms of structure, morphology and surface properties. The electrocatalytic activity for ethanol oxidation was studied in a direct ethanol fuel cell (DEFC) at 70 degrees C and 90 degrees C. Electrochemical and physico-chemical data indicated that a proper balance of Pt and Sn species in the near surface region was necessary to maximize the reaction rate. The best atomic surface composition, in terms of electrochemical performance, was Pt:Sn 65:35 corresponding to a bulk composition 75:25 namely Pt3Sn1/C. The reaction products of ethanol electro-oxidation in single cell and their distribution as a function of the nature of catalyst were determined. Essentially, acetaldehyde and acetic acid were detected as the main reaction products; whereas, a lower content of CO2 was formed. The selectivity toward acetic acid vs. acetaldehyde increased with the increase of the Sn content and decreased by decreasing the concentration of the reducing agent used in the catalyst preparation. According to the recent literature, these results have been interpreted on the basis of ethanol adsorption characteristics and ligand effects occurring for Sn-rich electrocatalysts. (C) 2012 Elsevier Ltd. All rights reserved.

Semi-supervised dimensionality reduction based on partial least squares for visual analysis of high dimensional data

Dimensionality reduction is employed for visual data analysis as a way to obtaining reduced spaces for high dimensional data or to mapping data directly into 2D or 3D spaces. Although techniques have evolved to improve data segregation on reduced or visual spaces, they have limited capabilities for adjusting the results according to user's knowledge. In this paper, we propose a novel approach to handling both dimensionality reduction and visualization of high dimensional data, taking into account user's input. It employs Partial Least Squares (PLS), a statistical tool to perform retrieval of latent spaces focusing on the discriminability of the data. The method employs a training set for building a highly precise model that can then be applied to a much larger data set very effectively. The reduced data set can be exhibited using various existing visualization techniques. The training data is important to code user's knowledge into the loop. However, this work also devises a strategy for calculating PLS reduced spaces when no training data is available. The approach produces increasingly precise visual mappings as the user feeds back his or her knowledge and is capable of working with small and unbalanced training sets.

AURICULOTHERAPY EFFECTIVENESS IN THE REDUCTION OF ANXIETY IN NURSING STUDENTS

The objective of this single-blinded randomized controlled trial was to assess anxiety levels in nursing school students of the Beneficencia Portuguesa Hospital (Sao Paulo) and the effectiveness of auriculotherapy in the reduction of these levels. The Trait-Anxiety Inventory State was applied at the beginning of the study, after 8 and 12 sessions, and at follow-up (15 days). The sample was comprised of 71 students divided into 3 groups: control without intervention (25), auriculotherapy (24), and placebo (22). The analysis of variance (ANOVA) showed statistically significant differences post hoc between the control and auriculotherapy groups at 2nd (p=0.000), 3rd (p=0.012) and 4th assessments (p=0.005), and between placebo and control groups at 2nd assessment (p=0.003). Auriculotherapy with Shenmen and Brain Stem points was more effective (20.97%) than sham points (13.74%) for reduction of anxiety levels in Nursing students, but studies with more representative samples are recommended.

Sialic acid reduction in the saliva of streptozotocin induced diabetic rats

Objective: Diabetes causes changes in the salivary glands and in the composition of saliva, as well as symptoms such as dry mouth and hyposalivation. Therefore, this study aimed at investigating changes in salivary secretion and composition, in response to parasympathetic stimuli, in diabetic rats induced with streptozotocin. Design: Diabetes was induced by a single intraperitoneal injection of streptozotocin. Thirty days after diabetes induction, the animals were anaesthetized and salivation was stimulated by an intraperitoneal injection of Pilocarpine (0.6 mg/kg body weight) dissolved in distilled water. Saliva was collected for 40 min and immediately stored at -80 degrees C until analysis. The salivary flow rate, amount of total protein, amylase and peroxidase activities, and free and total sialic acid contents were measured. Results: Salivary flow rate was reduced in the diabetic group (p < 0.05). Moreover, increases in total protein amount and in amylase and peroxidase activities were observed in diabetic animals. No difference was observed for free sialic acid content between groups. On the other hand, a significantly decrease in the total sialic acid content was observed in the diabetic group (p < 0.05). Conclusions: Our findings suggest that a decrease in sialic acid in the saliva of diabetic animals can be related to xerostomia reported by diabetic patients. However, further clinical trials are needed to verify if the decrease in sialic acid also occurs in human saliva. (C) 2012 Elsevier Ltd. All rights reserved.

Relaxation of Adaptive Evolution during the HIV-1 Infection Owing to Reduction of CD4+T Cell Counts

Background: The first stages of HIV-1 infection are essential to establish the diversity of virus population within host. It has been suggested that adaptation to host cells and antibody evasion are the leading forces driving HIV evolution at the initial stages of AIDS infection. In order to gain more insights on adaptive HIV-1 evolution, the genetic diversity was evaluated during the infection time in individuals contaminated by the same viral source in an epidemic cluster. Multiple sequences of V3 loop region of the HIV-1 were serially sampled from four individuals: comprising a single blood donor, two blood recipients, and another sexually infected by one of the blood recipients. The diversity of the viral population within each host was analyzed independently in distinct time points during HIV-1 infection. Results: Phylogenetic analysis identified multiple HIV-1 variants transmitted through blood transfusion but the establishing of new infections was initiated by a limited number of viruses. Positive selection (d(N)/d(S)>1) was detected in the viruses within each host in all time points. In the intra-host viruses of the blood donor and of one blood recipient, X4 variants appeared respectively in 1993 and 1989. In both patients X4 variants never reached high frequencies during infection time. The recipient, who X4 variants appeared, developed AIDS but kept narrow and constant immune response against HIV-1 during the infection time. Conclusion: Slowing rates of adaptive evolution and increasing diversity in HIV-1 are consequences of the CD4+ T cells depletion. The dynamic of R5 to X4 shift is not associated with the initial amplitude of humoral immune response or intensity of positive selection.

On response time reduction of electrothermomechanical MEMS using topology optimization

Electrothermomechanical MEMS are essentially microactuators that operate based on the thermoelastic effect induced by the Joule heating of the structure. They can be easily fabricated and require relatively low excitation voltages. However, the actuation time of an electrothermomechanical microdevice is higher than the actuation times related to electrostatic and piezoelectric actuation principles. Thus, in this research, we propose an optimization framework based on the topology optimization method applied to transient problems, to design electrothermomechanical microactuators for response time reduction. The objective is to maximize the integral of the output displacement of the actuator, which is a function of time. The finite element equations that govern the time response of the actuators are provided. Furthermore, the Solid Isotropic Material with Penalization model and Sequential Linear Programming are employed. Finally, a smoothing filter is implemented to control the solution. Results aiming at two distinct applications suggest the proposed approach can provide more than 50% faster actuators. (C) 2012 Elsevier B.V. All rights reserved.

Objective reduction in adenoid tissue after mometasone furoate treatment

Objective: Chronic rhinitis and adenoid hypertrophy are the main causes of nasal obstruction in children and proper treatment of these factors seem essential for controlling nasal obstructive symptoms. This study aims to evaluate the effects of topical mometasone treatment on symptoms and size of adenoid tissue in children with complaints of nasal obstruction and to compare this approach to continuous nasal saline douching plus environmental control alone. Methods: Fifty-one children with nasal obstructive complaints were submitted to a semi-structured clinical questionnaire on nasal symptoms, prick test and nasoendoscopy. Nasoendoscopic images were digitalized, and both adenoid and nasopharyngeal areas were measured in pixels. The relation adenoid/nasopharyngeal area was calculated. Patients were subsequently re-evaluated in two different periods: following 40 days of treatment with nasal douching and environmental prophylaxis alone; and after an subsequent 40 day-period, when topical mometasone furoate (total dose: 100 mu g/day) was superposed. Results: Nasal symptoms and snoring significantly improved after nasal douching, and an additional gain was observed when mometasone furoate was included to treatment. Saline douching did not influence the adenoid area, whereas a significant reduction on adenoid tonsil was observed after 40 days of mometasone treatment (P < 0.0001). Conclusion: Nasal saline douching significantly improved nasal symptoms without interfering in adenoid dimension. In contrast, mometasone furoate significantly reduced adenoid tissue, and led to a supplementary improvement of nasal symptoms. (C) 2012 Elsevier Ireland Ltd. All rights reserved.

Drag reduction phenomenon in viscous oil-water dispersed pipe flow: Experimental investigation and phenomenological modeling

An experimental study on drag-reduction phenomenon in dispersed oil-water flow has been performed in a 26-mm-i.d. Twelve meter long horizontal glass pipe. The flow was characterized using a novel wire-mesh sensor based on capacitance measurements and high-speed video recording. New two-phase pressure gradient, volume fraction, and phase distribution data have been used in the analysis. Drag reduction and slip ratio were detected at oil volume fractions between 10 and 45% and high mixture Reynolds numbers, and with water as the dominant phase. Phase-fraction distribution diagrams and cross-sectional imaging of the flow suggested the presence of a higher amount of water near to the pipe wall. Based on that, a phenomenology for explaining drag reduction in dispersed flow in a flow situation where slip ratio is significant is proposed. A simple phenomenological model is developed and the agreement between model predictions and data, including data from the literature, is encouraging. (c) 2011 American Institute of Chemical Engineers AIChE J, 2012

Determination of decimal reduction time (D value) of chemical agents used in hospitals for disinfection purposes

Abstract Background Prior to the selection of disinfectants for low, intermediate and high (sterilizing) levels, the decimal reduction time, D-value, for the most common and persistent bacteria identified at a health care facility should be determined. Methods The D-value was determined by inoculating 100 mL of disinfecting solution with 1 mL of a bacterial suspension (104 – 105 CFU/mL for vegetative and spore forms). At regular intervals, 1 mL aliquots of this mixture were transferred to 8 mL of growth media containing a neutralizing agent, and incubated at optimal conditions for the microorganism. Results The highest D-values for various bacteria were determined for the following solutions: (i) 0.1% sodium dichloroisocyanurate (pH 7.0) – E. coli and A. calcoaceticus (D = 5.9 min); (ii) sodium hypochlorite (pH 7.0) at 0.025% for B. stearothermophilus (D = 24 min), E. coli and E. cloacae (D = 7.5 min); at 0.05% for B. stearothermophilus (D = 9.4 min) and E. coli (D = 6.1 min) and 0.1% for B. stearothermophilus (D = 3.5 min) and B. subtilis (D = 3.2 min); (iii) 2.0% glutaraldehyde (pH 7.4) – B. stearothermophilus, B. subtilis (D = 25 min) and E. coli (D = 7.1 min); (iv) 0.5% formaldehyde (pH 6.5) – B. subtilis (D = 11.8 min), B. stearothermophilus (D = 10.9 min) and A. calcoaceticus (D = 5.2 min); (v) 2.0% chlorhexidine (pH 6.2) – B. stearothermophilus (D = 9.1 min), and at 0.4% for E. cloacae (D = 8.3 min); (vi) 1.0% Minncare® (peracetic acid and hydrogen peroxide, pH 2.3) – B. stearothermophilus (D = 9.1 min) and E. coli (D = 6.7 min). Conclusions The suspension studies were an indication of the disinfectant efficacy on a surface. The data in this study reflect the formulations used and may vary from product to product. The expected effectiveness from the studied formulations showed that the tested agents can be recommended for surface disinfection as stated in present guidelines and emphasizes the importance and need to develop routine and novel programs to evaluate product utility.

Cardiometabolic risk reduction through lifestyle intervention programs in the Brazilian public health system

Public health strategies to reduce cardiovascular morbidity and mortality should focus on global cardiometabolic risk reduction. The efficacy of lifestyle changes to prevent type 2 diabetes have been demonstrated, but low-cost interventions to reduce cardiometabolic risk in Latin-America have been rarely reported. Our group developed 2 programs to promote health of high-risk individuals attending a primary care center in Brazil. This study compared the effects of two 9-month lifestyle interventions, one based on medical consultations (traditional) and another with 13 multi-professional group sessions in addition to the medical consultations (intensive) on cardiometabolic parameters. Adults were eligible if they had pre-diabetes (according to the American Diabetes Association) and/or metabolic syndrome (International Diabetes Federation criteria for Latin-America). Data were expressed as means and standard deviations or percentages and compared between groups or testing visits. A p-value < 0.05 was considered significant. Results: 180 individuals agreed to participate (35.0% men, mean age 54.7 ± 12.3 years, 86.1% overweight or obese). 83 were allocated to the traditional and 97 to the intensive program. Both interventions reduced body mass index, waist circumference and tumor necrosis factor-α. Only intensive program reduced 2-hour plasma glucose and blood pressure and increased adiponectin values, but HDL-cholesterol increased only in the traditional. Also, responses to programs were better in intensive compared to traditional program in terms of blood pressure and adiponectin improvements. No new case of diabetes in intensive but 3 cases and one myocardial infarction in traditional program were detected. Both programs induced metabolic improvement in the short-term, but if better results in the intensive are due to higher awareness about risk and self-motivation deserves further investigation. In conclusion, these low-cost interventions are able to minimize cardiometabolic risk factors involved in the progression to type 2 diabetes and/or cardiovascular disease.

Contribution to assessing the stiffness reduction of structural elements in the global stability analysis of precast concrete multi-storey buildings

This study deals with the reduction of the stiffness in precast concrete structural elements of multi-storey buildings to analyze global stability. Having reviewed the technical literature, this paper present indications of stiffness reduction in different codes, standards, and recommendations and compare these to the values found in the present study. The structural model analyzed in this study was constructed with finite elements using ANSYS® software. Physical Non-Linearity (PNL) was considered in relation to the diagrams M x N x 1/r, and Geometric Non-Linearity (GNL) was calculated following the Newton-Raphson method. Using a typical precast concrete structure with multiple floors and a semi-rigid beam-to-column connection, expressions for a stiffness reduction coefficient are presented. The main conclusions of the study are as follows: the reduction coefficients obtained from the diagram M x N x 1/r differ from standards that use a simplified consideration of PNL; the stiffness reduction coefficient for columns in the arrangements analyzed were approximately 0.5 to 0.6; and the variation of values found for stiffness reduction coefficient in concrete beams, which were subjected to the effects of creep with linear coefficients from 0 to 3, ranged from 0.45 to 0.2 for positive bending moments and 0.3 to 0.2 for negative bending moments.