Polyvinyl siloxane template aids in recontouring natural teeth opposing single dentures

This article describes a procedure that provides proper reduction of natural teeth opposing complete dentures. By use of a polyvinyl siloxane prosthetic template, natural dentition can be reduced to a more favorable plane, which will facilitate denture construction. This procedure will eliminate the risk of arbitrary grinding and will minimize guesswork through guided intraoral reduction.     

Color image segmentation: a novel spatial fuzzy genetic algorithm

Image segmentation is a very important low-level vision task. It is the perceptual grouping of pixels based on some similarity criteria. In this article, we have applied spatial fuzzy genetic algorithm (SFGA) for the unsupervised segmentation of color images. The SFGA adds diversity to the search process to find the global optima. The performance of SFGA is influenced by two factors: first, K number of clusters—should be known in advance; second, the initialization of the cluster centers. To overcome these issues, a progressive technique based on self-organizing map is presented to find out the optimal K number of clusters automatically. To handle the initialization problem, peaks are identified using the image color histograms. The genetic algorithm with fuzzy behavior maximizes the fuzzy separation and minimizes the global compactness among the segments. The segmentation is performed on wavelet transform image which not only reduces the dimensionality and computational cost but also makes more compact segments. A novel pruning technique is proposed to handle the problem of over-segmentation. The results show that the proposed technique outperforms state-of-the-art methods.     

A robust predictive model for base shear of steel frame structures using a hybrid genetic programming and simulated annealing method

This study presents a new empirical model to estimate the base shear of plane steel structures subjected to earthquake load using a hybrid method integrating genetic programming (GP) and simulated annealing (SA), called GP/SA. The base shear of steel frames was formulated in terms of the number of bays, number of storey, soil type, and situation of braced or unbraced. A classical GP model was developed to benchmark the GP/SA model. The comprehensive database used for the development of the correlations was obtained from finite element analysis. A parametric analysis was carried out to evaluate the sensitivity of the base shear to the variation of the influencing parameters. The GP/SA and classical GP correlations provide a better prediction performance than the widely used UBC code and a neural network-based model found in the literature. The developed correlations may be used as quick checks on solutions developed by deterministic analyses.     

Adiabatic nanofocusing scattering-type optical nanoscopy of individual gold nanoparticles

We explore imaging of local electromagnetic fields in the vicinity of metallic nanoparticles using a grating-coupled scattering-type near-field scanning optical microscope. In this microscope, propagating surface plasmon polariton wavepackets are launched onto smooth gold tapers where they are adiabatically focused toward the nanometer-sized taper apex. We report two-dimensional raster-scanned optical images showing pronounced near-field contrast and demonstrating sub-30 nm resolution imaging of localized surface plasmon polariton fields of spherical and elliptical nanoparticles. By comparison to three-dimensional finite-difference time domain simulations, we conclude that virtually background-free near-field imaging is achieved. The microscope combines deep subwavelength resolution, high local field intensities and a straightforward imaging contrast, making it interesting for a variety of applications in linear and nonlinear nanospectroscopy.     

Oxidative desulfurization of 4,6-dimethyldibenzothiophene in a two impinging streams spray reactor

Oxidative desulfurization of 4,6-dimethyldibenzothiophene was performed in a two impinging streams spray reactor (TIS-SR) using H₂O₂ and phosphotungstic acid as oxidant and catalyst, respectively. The reaction was optimized using response surface methodology. The reaction constant of a pseudo first order rate based on the dynamic data obtained for the optimal operation conditions was calculated to be 9.45 × 10^?4 s^?1. It is about one order of magnitude larger than the one calculated for a conventional ideal stirred batch reactor at the same reaction conditions (1.03 × 10^?4 s^?1). Accordingly, ODS reaction rate may be substantially enhanced using TIS-SR.     

Performance evaluation of a continuous flow Photo-Impinging Streams Cyclone Reactor for phenol degradation

In this study, an impinging streams cyclone reactor has been utilized as a novel apparatus in photocatalytic degradation of phenol. Degussa P25 TiO₂ nano particles have been applied as the photocatalyst under UV radiation. The operating parameters including catalyst loading, pH, initial phenol concentration and light Intensity have been found to affect the efficiency of the photocatalytic degradation process within this photoreactor. Photocatalytic degradation of phenol has been also investigated in a continuous flow impinging streams system. The results have shown a higher efficiency and an increased performance capability of the present reactor in comparison with the conventional processes.