From Metalloligand to Extended 3D Network: Synthesis, Crystal Structure and Magnetic Property of {[Cu(en)2][Cu(μ3-pydc)2]·6H2O}n

A novel 2D coordination polymer, {[Cu(en)₂][Cu(μ₃-pydc)₂]·6H₂O} _n (1) pyridine-2,3-dicarboxylic acid (pydcH₂); ethylenediamine (en), based on the metalloligand [Cu(μ-pydcH)₂] _n , has been prepared and characterized by IR, UV–Vis and ESR spectroscopy, thermal analysis, differential scanning calorimetry and single crystal X-ray diffraction techniques. The temperature dependent magnetic properties have also been studied. The pydc ligand exhibits tetradentate-μ₃ bridging mode, being coordinated through three carboxylate oxygens and one nitrogen atom. The complex contains two copper(II) ions that exhibit two different coordination environment with two en and two pydc ligands. The single crystal structure shows that the complex forms a 3D framework with 2D layers along the c-axis. Van der Waals interactions are responsible for the self-assembly of the layer into a 3D network.     

Effect of saliva contamination on shear bond strength and microleakage of one-bottle etch-and-rinse and self-etch adhesives: scanning electron and confocal laser microscopic analyses

Purpose: To evaluate the effect of saliva contamination on shear bond strength, microleakage, and microstructure of the adhesive interface in two different adhesive systems by using scanning electron microscopy (SEM) and confocal laser microscopy (CLSM). Materials and methods: Randomly, 228 third molars were allocated to six groups for an etch-and-rinse adhesive One-Step Plus (Bisco Inc.) and a self-etch adhesive G Bond (GC Corp.): Group 1 – manufacturer’s instructions were followed; Group 2 – involved contamination and drying before adhesive application; Group 3 – involved contamination, washing, and blot drying before adhesive application; Group 4 – involved contamination, etching, washing, and blot drying before adhesive application; Group 5 – involved contamination and drying after adhesive application, followed by adhesive reapplication; Group 6 – involved contamination and washing after adhesive application, followed by adhesive reapplication. Shear bond strength was tested after specimens were stored in distilled water at 37?°C for 24?h. Specimens were evaluated under a stereomicroscope for microleakage. Dentin–resin interfaces were evaluated by SEM and CLSM. Results: Group 2 for One-Step Plus and Group 3 for G Bond showed significantly lower bond strengths than control groups. Microleakage values were significantly greater at dentin than at enamel margins for all groups. In Group 2, for both adhesive systems, the highest microleakage was observed at dentin margins. Further, dentin–adhesive interfaces were not uniform and gaps were found by SEM and CLSM. Conclusions: The SEM and CLSM images demonstrated high variability of dentin–resin interfaces among saliva-contaminated groups. Rinsing the saliva and re-applying adhesive might be the best way to reduce the effect of saliva contamination on bond strength and microleakage.     

A comparative analysis of classification algorithms in data mining for accuracy, speed and robustness

Classification algorithms are the most commonly used data mining models that are widely used to extract valuable knowledge from huge amounts of data. The criteria used to evaluate the classifiers are mostly accuracy, computational complexity, robustness, scalability, integration, comprehensibility, stability, and interestingness. This study compares the classification of algorithm accuracies, speed (CPU time consumed) and robustness for various datasets and their implementation techniques. The data miner selects the model mainly with respect to classification accuracy; therefore, the performance of each classifier plays a crucial role for selection. Complexity is mostly dominated by the time required for classification. In terms of complexity, the CPU time consumed by each classifier is implied here. The study first discusses the application of certain classification models on multiple datasets in three stages: first, implementing the algorithms on original datasets; second, implementing the algorithms on the same datasets where continuous variables are discretised; and third, implementing the algorithms on the same datasets where principal component analysis is applied. The accuracies and the speed of the results are then compared. The relationship of dataset characteristics and implementation attributes between accuracy and CPU time is also examined and debated. Moreover, a regression model is introduced to show the correlating effect of dataset and implementation conditions on the classifier accuracy and CPU time. Finally, the study addresses the robustness of the classifiers, measured by repetitive experiments on both noisy and cleaned datasets.     

Cyclic fatigue resistance of rotary NiTi instruments produced with four different manufacturing methods

The aim of this study was to compare the cyclic fatigue resistance of rotary NiTi files, produced with four different manufacturing methods on specially designed dynamic models that simulated clinical conditions. In this study, 120 files, consisting of 30 files for Typhoon, ProTaper Next, RaCe, and Twisted Files nickel titanium rotary systems were used. The 30 files of each group were divided into three subgroups to be used in artificial canals with a 60° angle of curvature and radii of curvature of 2, 5, and 8 mm (n = 10). All files were rotated in the artificial canals until fracture occurred and the number of cycles to fracture was calculated. The data were analyzed using one‐ and two‐way analyses of variance and Tamhane multiple comparison tests. In all three groups, Typhoon instruments had the highest number of cycles to failure than the RaCe, ProTaper Next, and Twisted Files instruments, and the difference statistically significant (p < .05). There were no significant differences between the RaCe, ProTaper Next, and Twisted Files groups (p > .05). The CM wire Typhoon system was significantly more resistant to cyclic fatigue compared to the other file systems in all three artificial canals. When the fracture resistance of an instrument in three different artificial canals was compared, the mean NCFs decreased as the radius of the curvature of the canal decreased from 8 to 2 mm. Manufacturing method is one of the most important factors on cyclic fatigue resistance, also the radius of curvature effects the cyclic fatigue.     

Interfacial Tension in the CaO-Al<Subscript>2</Subscript>O<Subscript>3</Subscript>-SiO<Subscript>2</Subscript>-(MgO) Liquid Slag–Solid Oxide Systems

Interfacial phenomenon is critical in metal processing and refining. While it is known to be important, there are little data available for key oxide systems in the literature. In this study, the interfacial tension (σ _LS) of liquid slag on solid oxides (alumina, spinel, and calcium aluminate), for a range of slags in the CaO-Al₂O₃-SiO₂-(MgO) system at 1773 K (1500 °C), has been evaluated. The results show that basic ladle-type slags exhibit lower σ _LS with oxide phases examined compared to that of acid tundish-type slags. Also, within the slag types (acid and base), σ _LS was observed to decrease with increasing slag basicity. A correlation between σ _LS and slag structure was observed, i.e., σ _LS was found to decrease linearly with increasing of slag optical basicity (Λ) and decrease logarithmically with decreasing of slag viscosity from acid to base slags. This indicated a higher σ _LS as the ions in the slag become larger and more complex. Through a work of adhesion (W) analysis, it was shown that basic ladle slags with lower σ _LS result in a greater W, i.e., form a stronger bond with the solid oxide phases examined. This indicates that all other factors being equal, the efficiency of inclusion removal from steel of inclusions of similar phase to these solid oxides would be greater.     

<Emphasis Type="Italic">In Situ</Emphasis> Observation of Calcium Aluminate Inclusions Dissolution into Steelmaking Slag

The dissolution rate of calcium aluminate inclusions in CaO-SiO₂-Al₂O₃ slags has been studied using confocal scanning laser microscopy (CSLM) at elevated temperatures: 1773 K, 1823 K, and 1873 K (1500 °C, 1550 °C, and 1600 °C). The inclusion particles used in this experimental work were produced in our laboratory and their production technique is explained in detail. Even though the particles had irregular shapes, there was no rotation observed. Further, the total dissolution time decreased with increasing temperature and decreasing SiO₂ content in the slag. The rate limiting steps are discussed in terms of shrinking core models and diffusion into a stagnant fluid model. It is shown that the rate limiting step for dissolution is mass transfer in the slag at 1823 K and 1873 K (1550 °C and 1600 °C). Further investigations are required to determine the dissolution mechanism at 1773 K (1500 °C). The calculated diffusion coefficients were inversely proportional to the slag viscosity and the obtained values for the systems studied ranged between 5.64 × 10^?12 and 5.8 × 10^?10 m²/s.     

Investigation of luminescence centers inside InGaN/GaN multiple quantum well over a wide range of temperature and injection currents

Journal of Materials Science: Materials in Electronics - InGaN/GaN multiple quantum well-based light-emitting diode LEDs were investigated over a wide range of injection currents (0.04 mA–0.1...     

Performance analysis of drying of green olive in a tray dryer

This paper deals with the performance evaluation of a single layer drying process of green olives in a tray dryer using exergy analysis method. Green olive was used as the test material being dried. Drying process was realized at four different drying air temperatures (40, 50, 60 and 70 °C) and a constant relative humidity of 15%. The effects of temperatures and mass flow rates were investigated. Maximum exergy efficiency of the drying chamber was obtained at a temperature of 70 °C and a drying air mass flow rate of 0.015 kg/s with 0.0004 kg/s of olive. The exergy efficiency values were found to be in the range of 68.65%–91.79% from 40 °C to 70 °C with drying air mass flow rates of 0.01 kg/s–0.015 kg/s.     

Sorption of remazol brilliant blue R onto polyurethane‐type foam prepared from peanut shell

The powders of peanut shell is first liquefied with the mixture of polyethylene glycol‐400 and monoethylene glycol (MEG) using sulfuric acid at 160°C for 2 h. Polyurethane (PU)‐type rigid foam is prepared from the reaction between peanut shell liquefied with the MEG and diphenylmethane diisocyanate. Then the PU foam is used as a sorbent for the removal of the remazol brilliant blue R from aqueous solution. The sorption of the dye increases with increasing initial concentration, temperature, and ionic strength, while decreasing with increasing pH. From the isotherm and kinetic studies, it is seen that the sorption process is in the best agreement with the Langmuir isotherm and the pseudo second‐order kinetic model. Desorption and FTIR studies show that a chemisorption process occurs between dye and foam, probably indicating electrostatic interactions. The thermodynamic parameters (i.e., standard free energy, standard enthalpy, and standard entropy) are determined, and the results obtained are discussed in detail. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci, 2013