Effect of annealing temperature on ZnO:Al/p-Si heterojunctions

Al-doped, zinc oxide (ZnO:Al) films with a 1.2 at.% Al concentration were deposited on p-type silicon wafers using a sol-gel dip coating technique to produce a ZnO:Al/p-Si heterojunction. Following deposition and subsequent drying processes, the films were annealed in vacuum at five different temperatures between 550 and 900 °C for 1 h. The resistivity of the films decreased with increasing annealing temperature, and an annealing temperature of 700 °C provided controlled current flow through the ZnO:Al/p-Si heterojunction up to 20 V. The ZnO:Al film deposited on a p-type silicon wafer with 1.2 at.% Al concentration was concluded to have the potential for use in electronic devices as a diode after annealing at 700 °C.     

Self Controlling Tabu Search algorithm for the Quadratic Assignment Problem

This paper addresses the application of the principles of feedback and self-controlling software to the tabu search algorithm. We introduce two new reaction strategies for the tabu search algorithm. The first strategy treats the tabu search algorithm as a target system to be controlled and uses a control-theoretic approach to adjust the algorithm parameters that affect search intensification. The second strategy is a flexible diversification strategy which can adjust the algorithm’s parameters based on the search history. These two strategies, combined with tabu search, form the Self Controlling Tabu Search (SC-Tabu) algorithm. The algorithm is implemented and tested on the Quadratic Assignment Problem (QAP). The results show that the self-controlling features of the algorithm make it possible to achieve good performance on different types of QAP instances.     

Time series representation and similarity based on local autopatterns

Time series data mining has received much greater interest along with the increase in temporal data sets from different domains such as medicine, finance, multimedia, etc. Representations are important to reduce dimensionality and generate useful similarity measures. High-level representations such as Fourier transforms, wavelets, piecewise polynomial models, etc., were considered previously. Recently, autoregressive kernels were introduced to reflect the similarity of the time series. We introduce a novel approach to model the dependency structure in time series that generalizes the concept of autoregression to local autopatterns. Our approach generates a pattern-based representation along with a similarity measure called learned pattern similarity (LPS). A tree-based ensemble-learning strategy that is fast and insensitive to parameter settings is the basis for the approach. Then, a robust similarity measure based on the learned patterns is presented. This unsupervised approach to represent and measure the similarity between time series generally applies to a number of data mining tasks (e.g., clustering, anomaly detection, classification). Furthermore, an embedded learning of the representation avoids pre-defined features and an extraction step which is common in some feature-based approaches. The method generalizes in a straightforward manner to multivariate time series. The effectiveness of LPS is evaluated on time series classification problems from various domains. We compare LPS to eleven well-known similarity measures. Our experimental results show that LPS provides fast and competitive results on benchmark datasets from several domains. Furthermore, LPS provides a research direction and template approach that breaks from the linear dependency models to potentially foster other promising nonlinear approaches.     

The use of slurry sampling for the determination of manganese and copper in various samples by electrothermal atomic absorption spectrometry

Manganese and copper in multivitamin-mineral supplements and standard reference materials were determined by slurry sampling electrothermal atomic absorption spectrometry. Slurries were prepared in an aqueous solution containing Triton X-100. The effects of different parameters such as ratio of solid to liquid phase volume, total slurry volume and addition of Triton X-100 as a dispersant on the analytical results were investigated. The graphite furnace programs were optimized for slurry sampling depending on the analytes and their concentrations in the samples. The linear calibration method with aqueous standard solutions was used for the quantification. At optimum experimental conditions, R.S.D. values were below 5%. The analytes were determined in the limits of 95% confidence level with respect to certified values in coal and soil standard reference materials and to those found by wet-digestion in multivitamin-mineral supplements. Detection limits (3delta) for Mn and Cu were 0.10 microg L(-1) and 1.82 microg L(-1) for 10 microL coal standard reference material slurry, respectively.     

Successive Boronizing and Austempering for GGG40 Grade Ductile Iron

Boronizing and austempering were successively applied to a GGG40 grade ductile iron in order to combine the advantages of both process in a single treatment. This new procedure formed a 30 μm thick boride layer on the surface with subsurface matrix structure consisted of acicular ferrite and retained austenite. Reciprocating wear tests showed that successive boronizing and austempering exhibited considerably higher wear resistance than conventional boronizing having a subsurface matrix structure consisting of ferrite and pearlite.     

Determination of antibacterial effects and total phenolic contents of grape (Vitis vinifera L.) seed extracts

In the study, antibacterial activities of the seed extracts of three different grapes were examined against fifteen bacteria, and total phenolic contents of the extracts were additionally determined. The contents of total phenolic compounds of the grape seed extracts were 589.09 (Hasandede), 506.60 (Emir) and 549.54 (Kalecik Karasi) mg gallic acid equivalent (GAE) per gram with acetone:water:acetic acid (90:9.5:0.5). These extracts at 1%, 2.5%, 5% and 10% concentrations were tested for their antibacterial effects by using the agar diffusion method against some pathogenic and spoilage bacteria including Aeromonas hydrophila, Bacillus cereus, Enterobacter aerogenes, Enterococcus faecalis, Escherichia coli, E. coli O157:H7, Klebsiella pneumoniae, Mycobacterium smegmatis, Proteus vulgaris, Pseudomonas aeruginosa, Pseudomonas fluorescens, Salmonella enteritidis, Salmonella typhimurium, Staphylococcus aureus and Yersinia enterocolitica. All tested bacteria were inhibited by the grape seed extracts using agar well diffusion method. The most sensitive of the bacteria was A. hydrophila while Hasandede grape seed extract was the most inhibitive extract on test bacteria. Hasandede seed extract at 10% concentration gave the largest inhibition zone diameter (30.67 mm) against A. hydrophila. According to serial dilution method, while all the grape seed extracts at 0.5% and 1% concentrations had generally bacteriostatic activities against E. coli O157:H7, the same extracts appeared to have bactericidal effects at concentrations above 2.5%. In addition, the extracts at all concentrations had bactericidal activities against S. aureus at the end of 48 h. and A. hydrophila at the end of 1 h.     

Bond Strength of Porcelain Bonded to Enamel and Dentin Surfaces Prepared with Different Surface Treatments

Although acid etching is routinely used to condition tooth surfaces, it increases the caries susceptibility of enamel and enhances enamel demineralization; thus the role of alternative surface treatments such as alumina air abrasion and erbium-doped yttrium aluminium garnet (Er:YAG) laser irradiation for tooth conditioning is controversial. This study was undertaken to compare the effects of different conditioning methods on the shear bond strength (SBS) of resin cement on enamel and dentin. Prepared permanent human dentin and enamel samples (N = 210) embedded in clear acrylic resin were conditioned by 37% phosphoric acid etching, 50-µm alumina air abrasion, Er:YAG laser irradiation (120 mJ, 10 Hz, medium short pulse mode), or their combinations. Porcelain laminates were cemented by using photopolymerizing luting composite. SBS was evaluated after thermal cycling (10,000 cycles, 5–55°C) and fracture types (adhesive, cohesive, or mixed) were observed by stereomicroscopy. Data were analyzed by Kruskal–Wallis analysis of variance and followed by Tamhane's test (p < 0.05). Enamel and dentin specimens showed significant differences in SBS (p < 0.000). Er:YAG laser etching presents successful alternatives to acid etching on dentin surfaces; it does not enhance adhesion of the resin cement on enamel surfaces.