Effect of fluoride solutions on the shear bond strength of orthodontic brackets

The aim of this in vitro study was to evaluate the shear bond strength of brackets after pre-treatment with different fluoride solutions. This study used 48 freshly extracted sound bovine incisors that were randomly assigned to 4 experimental groups (n=12). CG: (control) without treatment; NF: 4 min application of neutral fluoride; APF: application of 1.23% acidulated phosphate fluoride (APF) for 4 min; and SFV: application of 5% sodium fluoride varnish for 6 h. For each group, after surface treatment, prophylaxis of enamel and bracket bonding with Transbond XT composite resin (3M) were performed following the manufacturer's specifications. The shear bond strength was performed with a universal testing machine 24 h after fixing the brackets. The tooth surfaces were analyzed to verify the adhesive remnant index (ARI). Data were analyzed statistically by ANOVA and Tukey's test (α=0.05). There was statistically significant difference among the groups (p<0.0001). CG and NF groups presented significantly higher bond strength than APF and SFV. There was no significant difference between CG and NF or between APF and SFV (p>0.05). The analysis of ARI scores revealed that most failures occurred at the enamel-resin interface. It may be concluded that the pre-treatment of enamel with 1.23% APF and 5% SFV prior to fixing orthodontic brackets reduces shear bond strength values.

Thermal, rheological, and structural behaviors of natural and modified cassava starch granules, with sodium hypochlorite solutions

The use of chemically modified starches is widely accepted in various industries, with several applications. In this research, natural cassava starch granules were treated with standard sodium hypochlorite solution at 0.8, 2.0, and 5.0 g Cl/100 g starch. The native and modified starch samples were investigated by means of the following techniques: simultaneous thermogravimetry-differential thermal analysis, which allowed us to verify the thermal decomposition associated with endothermic or exothermic phenomena; and differential scanning calorimetry that was used to determine gelatinization enthalpy as well as the rapid viscoamylographic analysis that provided the pasting temperature and viscosity. By means of non-contact-atomic force microscopy method and X-ray powder patterns diffractometry, it was possible to observe the surface morphology, topography of starch granules, and alterations in the granules' crystallinity. © 2012 Akadémiai Kiadó, Budapest, Hungary.

Growth of TiO2 nanotubes by anodization of Ti-7.5Mo in NH 4F solutions

Titanium and its alloys are widely used as biomaterials due to their mechanical, chemical and biological properties. To enhance the biocompatibility of titanium alloys, various surface treatments have been proposed. In particular, the formation of titanium oxide nanotubes layers has been extensively examined. According to the literature, it is possible to induce the growth of TiO2 on the surface of titanium, employing the aqueous anodizing electrolyte. This Ti-7.5Mo alloy was anodized in glycerol electrolytes containg 0.25 wt% of NH4F, with variations in time, voltage and calcinations temperature. After anodization, the sample surfaces were analyzed with a field emission scanning electron microscopy, DRX and contact angle measurements. It was possible to observe the formation of TiO2 on the surface and these findings represent a simple surface treatment for Ti alloys that has high potential for biomedical applications. Copyright © 2013 American Scientific Publishers. All rights reserved.

Influence of the indium concentration on microstructural and electrical properties of proton conducting NiO-BaCe0.9-xIn xY0.1O3-δ cermet anodes for IT-SOFC application

Optimization of the major properties of anodes based on proton conductors, such as microstructure, conductivity and chemical stability, is yet to be achieved. In this study we investigated the influence of indium on the chemical stability, microstructural and electrical characteristics of proton conducting NiO-BaCe0.9-xInxY0.1O 3-δ (NiO-BCIYx) anodes. Four compositions of cermet anode substrates NiO-BCIYx were prepared using the method of evaporation and decomposition of solutions and suspensions (EDSS). Sintered anode substrates were reduced and their microstructural and electrical properties were examined before and after reduction as a function of the amount of indium. Anode substrates tested on chemical stability in the CO2 atmosphere showed high stability compared to anode substrates based on commonly used doped barium cerates. Microstructural properties of the anode pellets before and after testing in CO2 were investigated using X-ray diffraction analysis. Impedance spectroscopy measurements were used for evaluation of electrical properties of the anode pellets and the conductivity values of reduced anodes of more than 14 S cm-1 at 600 °C confirmed percolations through Ni particles. Under fuel cell operating conditions, the cell with a Ni-BCIY20 anode achieved the highest performance, demonstrating a peak power density 223 mW/cm2 at 700 °C confirming the functionality of Ni-BCIY anodes.© 2013 Elsevier B.V. All rights reserved.

Thermoanalytical study of nimesulide and their recrystallization products obtained from solutions of several alcohols

Thermogravimetry, differential scanning calorimetry, and vibrational infrared spectroscopy were used to study nimesulide and its recrystallization products that were obtained from solutions of several alcohols. The thermoanalytical measurements were performed in both air and nitrogen atmospheres and the results suggest that, under the experimental conditions used in this paper, it was possible to obtain neither polymorphic nor pseudopolymorphic forms of this drug. In this investigation, quantum chemical approach methods were used to determine the molecular structures using the Becke three-parameter hybrid method and the Lee-Yang-Parr correlation functional. The performed molecular calculations were done with the Gaussian 09 routine and the theoretical calculation results were correlated with the experimental IR vibrational spectrum. © 2013 Akadémiai Kiadó, Budapest, Hungary.

Traffic congestion: the problem and how to tackle it

As the culmination of a project financed by the Technical Cooperation Agency of the Federal Republic of Germany (GTZ), ECLAC has just published Congestión de tránsito - El problema y cómo enfrentarlo, Cuadernos de la Cepal series, No. 87. The text of 194 pages analyses the negative impacts of congestion and the multidisciplinary efforts that are needed to keep it under control, through the design of appropriate policies and measures. Congestion control is part of the development of a strategic vision of how a city should develop which can make it possible to harmonize the needs of mobility, growth and competitiveness, which are so necessary today and in the future, with the sustainability of cities and the improvement of their quality of life.The task is complex and it is not easy to find appropriate solutions. The present publication presents tools for tackling this crucial problem. Everything indicates that it calls for high professional and leadership qualities on the part of the authorities, and that it must have the active support of the citizens.This edition of the Bulletin presents a summary of the main conclusions of the publication and it is stressed that ECLAC can conduct local workshops to analyze the problem and how to tackle it.

Traffic congestion: the problem and how to deal with it

The text of 194 pages analyses the negative impacts of congestion and the multidisciplinary efforts that are needed to keep it under control, through the design of appropriate policies and measures. Congestion control is part of the development of a strategic vision of how a city should develop which can make it possible to harmonize the needs of mobility, growth and competitiveness, which are so necessary today and in the future, with the sustainability of cities and the improvement of their quality of life.The task is complex and it is not easy to find appropriate solutions. The present publication presents tools for tackling this crucial problem. Everything indicates that it calls for high professional and leadership qualities on the part of the authorities, and that it must have the active support of the citizens.This edition of the Bulletin presents a summary of the main conclusions of the publication and it is stressed that ECLAC can conduct local workshops to analyze the problem and how to tackle it.

Information and communication technology for disaster risk management in the Caribbean: subregional solutions to the challenge of limited human resource capacity

This document was adapted from a paper originally presented to the 8th Annual Caribbean Conference of Comprehensive Disaster Management, held in Montego Bay, Jamaica in December, 2013. It summarizes several activities that ECLAC has undertaken to assess the current state of information and communications technology (ICT) in the field of disaster risk management (DRM) as practiced in the Caribbean. These activities included an in-depth study that encompassed a survey of disaster management organizations in the region, an Expert Group Meeting attended by the heads of several national disaster offices, and a training workshop for professionals working in DRM in the Caribbean. One of the notable conclusions of ECLAC’s investigation on this topic is that the lack of human capacity is the single largest constraint that is faced in the implementation of ICT projects for DRM in the Caribbean. In considering strategies to address the challenge of limited human capacity at a regional level, two separate issues are recognized – the need to increase the ICT capabilities of disaster management professionals, and the need to make ICT specialists available to disaster management organizations to advise and assist in the implementation of technology-focused projects. To that end, two models are proposed to engage with this issue at a regional level. The first entails the establishment of a network of ICT trainers in the Caribbean to help DRM staff develop a strategic understanding of how technology can be used to further their organizational goals. The second is the development of “Centres of Excellence” for ICT in the Caribbean, which would enable the deployment of specialized ICT expertise to national disaster management offices on a project-by-project basis.

Malaria vaccine: roadblocks and possible solutions

Malaria remains the most prevalent and devastating parasitic disease worldwide. Vaccination is considered to be an approach that will complement other strategies for prevention and control of the disease in the future. In the last 10 years, intense studies aimed at the development of a malaria vaccine have provided important knowledge of the nature of the host immunological mechanisms of protection and their respective target antigens. It became well established that protective immune responses can be generated against the distinct stages of Plasmodium. However, in general, protective immune responses are directed at stage-specific antigens. The elucidation of the primary structure of these antigens made possible the generation of synthetic and recombinant proteins that are being extensively used in experimental immunizations against the infection. Today, several epitopes of limited polymorphism have been described and protective immunity can be generated by immunization with them. These epitopes are being tested as primary candidates for a subunit vaccine against malaria. Here we critically review the major roadblocks for the development of a malaria vaccine and provide some insight on how these problems are being solved.

Stability, characterization and functionality of proton conducting NiO-BaCe0.85-xNbxY0.15O3-delta cermet anodes for IT-SOFC application

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Corrosion kinetics and topography analysis of Ti-6Al-4V alloy subjected to different mouthwash solutions

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Chemical and morphological features of nanofilled composite resin: influence of finishing and polishing procedures and fluoride solutions

This study evaluated the influence of finishing and polishing procedures and differ-ent fluoride solutions on superficial morphology and chemistry of the nanofilled composite resinSupreme XT (3M) through the EDX analysis and SEM evaluation. Circular specimens (n 5 30) of 10mm diameter and 2 mm thickness were prepared, with half of the sample assays finished and polishedwith Super-Snap1sandpaper. The experimental groups were divided according to the presence or ab-sence of finishing and polishing and solutions (arti ficial saliva, 0.0 5% of manipulated sodium fluoridesolution, Fluordent Re ach, Oral B, Fluorgard). Specimens were immersed in each respective solutionfor 1 min per day, during 60 days and stored in artificial saliva at 37 6 18C between immersion peri-ods. Topography and chemical analysis was qualitative. It was observed that specimens submitted tofinishing and polishing procedures had lower superficial degradation. Fluoride solutio ns promoted su-perficial alterations on specimens, being the highest degradation obtained with Fluordent Reach. Itca n be concluded that finishing and polishing procedures and the immersion media influence the su-perficial morphology of composite resin tested; the Fluordent Reach was the flu oride solution thatmo st affected the material’s surface.

Studies on structural, morphological and electrical properties of Ce1-xErxO2-delta (x=0.05-0.20) as solid electrolyte for IT - SOFC

A series of four different powders ceria doped Ce1-xErxO2-delta (0.05 <= x <= 0.20) were synthesized by applying self-propagating reaction at room temperature (SPRT method). SPRT procedure is based on the self-propagating room temperature reaction between metal nitrates and sodium hydroxide, wherein the reaction is spontaneous and terminates extremely fast. The method is known to assure very precise stoichiometry of the final product in comparison with a tailored composition. XRPD, Raman spectroscopy, TEM and BET measurements were used to characterize the nanopowders at room temperature. It was shown that all obtained powders were single phase solid solutions with a fluorite-type crystal structure and all powder particles have nanometric size (about 3-4 nm). Densification was performed at 1550 degrees C, in an air atmosphere for 2 h. XRPD, SEM and complex impedance method measurements were carried out on sintered samples. Single phase form was evidenced for each sintered materials. The best value of conductivity at 700 degrees C amounted to 1.10 x 10(-2) Omega(-1) cm(-1) for Ce0.85Er0.O-3(2-delta) sample. Corresponding activation energies of conductivity amounted to 0.28 eV in the temperature range 500-700 degrees C. (C) 2015 Elsevier B.V. All rights reserved.

Variations in peak nasal inspiratory flow among healthy students after using saline solutions

Nasal hygiene with saline solutions has been shown to relieve congestion, reduce the thickening of the mucus and keep nasal cavity clean and moist. Evaluating whether saline solutions improve nasal inspiratory flow among healthy children. Students between 8 and 11 years of age underwent 6 procedures with saline solutions at different concentrations. The peak nasal inspiratory flow was measured before and 30min after each procedure. Statistical analysis was performed by means of t test, analysis of variance, and Tukey's test, considering p<0.05. We evaluated 124 children at all stages. There were differences on the way a same concentration was used. There was no difference between 0.9% saline solution and 3% saline solution by using a syringe. The 3% saline solution had higher averages of peak nasal inspiratory flow, but it was not significantly higher than the 0.9% saline solution. It is important to offer various options to patients.

Electrochemical behaviour of copper electrode in concentrated sulfuric acid solutions

The electrochemical behaviour of copper in 6.0 mol 1-1 sulfuric acid at 30°C, was studied by means of the potentiodynamic method. At low potential sweep rates, v < 200 m V s-1, the data reveal that the anodic process is basically constituted of copper dissolution and a film formation which inhibits further metal oxidation and which may undergo further dissolution. For higher potential sweep rates, a modification in the passivation region of the voltammogram is observed. It can be ascribed to a change in the passivation mechanism which possibly involves different surface species. The kineticrelationships derived from the potentiodynamic I/E curves obtained at low v suggest a film formation via a dissolution/precipitation mechanism. © 1993.