Qualitative analysis of files of four different rotary systems,before and after being used for the twelfth time

The aim of this study was to make a comparative evaluation of the surface topography of the cervical third and tip of four different rotary systems, before and after being used 12 times, in resin blocks with simulated root canals with standardized 45° curvatures, and analyzed by scanning electronic microscopy (SEM). A total of 1,440 resin blocks with simulated root canals and standardized curvatures were used. The blocks were divided into four groups and prepared by the crown down technique according to the manufacturers' recommendations: Group 1 (G1)—K3®, Group 2 (G2)—Protaper Universal®, Group 3 (G3)—Twisted Files®, and Group 4 (G4)—Biorace®. After each preparation, the instruments were washed and autoclaved. A total of 24 instruments were selected, being three new instruments and three after having been used for the 12th time, from each group. These instruments were analyzed by SEM. To perform the evaluation, 24 micrographs were observed by 12 evaluators who attributed a score to the images according to a template. In the qualitative analysis of the cervical region and tip of new instruments, it was observe that the files of Groups G4 and G2 were the least rough and those of G1, the roughest. In the same manner, the cervical region of the instruments was qualitatively analyzed after the 12th time of using them, and there was no statistically significant difference at a level of 1% (ANOVA P < 0.01) between G2 and G4 as well as between G1 and G3. As regards the tip, it was observed that there was no statistically significant difference, at a level of 1%, between the groups: G1 and G3, G1 and G4, and between G3 and G4, and there was statistically significant difference at a level of 1%, between group G2 and the other groups, with G3 having the greatest roughness (ANOVA P < 0.01). Microsc. Res. Tech., 2013. © 2012 Wiley Periodicals, Inc.     

The EuQoS system: a solution for QoS routing in heterogeneous networks [Quality of Service based Routing Algorithms for Heterogeneous Networks]

EuQoS is the acronym for "end-to-end quality of service support over heterogeneous networks", which is a European research project aimed at building an entire QoS framework, addressing all the relevant network layers, protocols, and technologies. This framework, which includes the most common access networks (xDSL, UMTS, WiFi, and LAN) is being prototyped and tested in a multidomain scenario throughout Europe, composing what we call the EuQoS system. In this article we present the novel QoS routing mechanisms that are being developed and evaluated in the framework of this project. The preliminary performance results validate the design choices of the EuQoS system, and confirm the potential impact this project is likely to have in the near future     

A Synthetic Approach to Oligomeric Phenylethynylsilylenes

Oligomers consisting of alternating phenylethynyl and monosilyl or disilanyl moieties were synthesized in 15–64% precipitated yields by the reactions of dilithiated ethynylbenzene with dichlorodimethylsilane, dichlorodiphenylsilane, and 1,2-dichloro-1,1,2,2-tetramethyldisilane. Degrees of polymerization were fairly low due to chain termination reactions involving the deprotonation of ethynyl groups by aryllithium species. The presence of butyl chain ends was confirmed by ¹H and ²⁹Si NMR spectroscopy. ²⁹Si NMR spectroscopy was utilized to illustrate the random pattern of connectivity along the oligomer backbones. The oligomers exhibit fluorescent behavior in solution.     

Synthesis,characterization and evaluation of phosphorylated resins in the removal of Pb<Superscript>2+</Superscript> from aqueous solutions

Phosphinic-derivative poly(styrene-co-divinylbenzene)-based on PS–DVB copolymers with different porosity degrees have been prepared by aromatic electrophilic substitution reaction using PCl₃/AlCl₃ followed by base-promoted hydrolysis. The phosphorylation reaction was analyzed by infra-red spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetry (TG/DTG). In addition, the phosphorous content of the phosphorylated copolymers was determined by spectrophotometry using the method based on sodium molybdate reactant so that the extension of that modification could be assessed. The performance of the phosphorylated resins in the extraction of Pb²⁺ from aqueous solutions in a batch system was also evaluated. The Pb²⁺ content was determined by atomic absorption spectrometry (AAS). These materials presented excellent extraction capacity under the contact time of 30 min and pH 6.     

Dynamic formation of SEBS copolymer submicrometric structures

Highly ordered A-B-A block copolymer arrangements in the submicrometric scale, resulting from dewetting and solvent evaporation of thin films, have inspired a variety of new applications in the nanometric world. Despite the progress observed in the control of such structures, the intricate scientific phenomena related to regular patterns formation are still not completely elucidated. SEBS is a standard example of a triblock copolymer that forms spontaneously impressive pattern arrangements. From macroscopic thin liquid films of SEBS solution, several physical effects and phenomena act synergistically to achieve well-arranged patterns of stripes and/or droplets. That is, concomitant with dewetting, solvent evaporation, and Marangoni effect, Rayleigh instability and phase separation also play important role in the pattern formation. These two last effects are difficult to be followed experimentally in the nanoscale, which render difficulties to the comprehension of the whole phenomenon. In this paper, we use computational methods for image analysis, which provide quantitative morphometric data of the patterns, specifically comprising stripes fragmentation into droplets. With the help of these computational techniques, we developed an explanation for the final part of the pattern formation, i.e. structural dynamics related to the stripes fragmentation.     

A morphological view of the sodium 4,4′‐distyrylbiphenyl sulfonate fluorescent brightness distribution on regenerated cellulose fibers

Evidence of the sorption of the whitening agent sodium 4,4′‐distyrylbiphenyl sulfonate in the presence of the anionic surfactant sodium dodecylsulfate or the cationic surfactant dodecyl trimethyl ammonium chloride on regenerated cellulose fibers is given by several microscopy techniques. Scanning electron microscopy provided images of the cylindrical fibers with dimensions of 3.5 cm (length) and 13.3 μm (thickness), with empty cores of 1 μm diameter and a smooth surface. Atomic force microscopy showed a fiber surface with disoriented nanometric domains using both tapping‐mode height and phase image modes. Atomic force microscopy also showed that the whitening agent and surfactant molecules were sorbed onto the fiber surface, in agreement with the adsolubilization sorption model. Transmission electron microscopy showed fibers with nanometric parallel cylinders, surrounded by holes where the fluorescent whitening molecules accumulated. On the basis of these techniques, we conclude that the sorption process occurs preferentially on the fiber surface in contact with the water solution, and under saturated conditions, the whitening agent penetrates into the pores and are simultaneously sorbed on the pore walls bulk, forming molecular aggregates. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Testing New In-Kiln Meter for Monitoring Lumber Moisture Content during Drying

The objective of this study was to test a new in-kiln sensor for monitoring lumber moisture content during industrial drying. The theoretical foundation of the technology was already known, because it is based on electrical conductivity, but the mechanism of implementation was new and required validation. For this reason, the technology was compared with two other widely used methods for assessing lumber moisture content, namely, the oven-drying and electrical capacitance methods. The tests were performed in a 120-m³ industrial kiln operated by a sawmill in the eighth region of Chile, and the results showed that the average moisture content at the end of drying was satisfactorily determined by the new in-line sensor. As predicted by theory, the sensor was not able to accurately measure moisture content above 25%, but it was still able to provide the equivalent of a drying curve for monitoring of the drying process.