Effect of root canal sealers on the push-out bond strengths of tooth-colored posts to root dentine

Objectives: This study evaluated the effect of different root canal sealers on the push-out bond strength of tooth-colored posts to root dentin. Material and methods: Eighty human mandibular premolar teeth with single roots were decoronated and randomly divided into two groups according to post material: G1–G5: Cytec blanco; G6–G10: Cosmopost. In each group, the specimens were further subgrouped according to the filling material plus sealer (n = 8): G1, G6: Gutta-percha + AH Plus; G2, G7: Resilon + Epiphany SE; G3, G8: Gutta-percha + Sealite; G4, G9: Gutta-percha + iRoot SP; and G5, G10: control (unobturated). Cytec blanco and Cosmopost of 1.4 mm diameter were adhesively luted to samples using Variolink II. Push-out test was performed in a universal testing machine, and failure modes were examined under stereomicroscope. Data were analyzed with the two-way ANOVA and post hoc Tukey’s tests. Statistical significance was set to 0.05. Results: Roots obturated with AH Plus (3.48 ± 1.41 MPa), Sealite (3.47 ± 0.65 MPa), and Resilon (3.36 ± 1.23 MPa) had the lowest bond strength (p < 0.005). iRoot SP and control group samples showed the highest bond strength values (7.38 ± 0.89 MPa and 6.43 ± 1.16 MPa, respectively) (p < 0.05). Significant differences were observed among tooth-colored posts and sealers (p < 0.05). Adhesive failures were predominant in all groups (48%). Conclusions: When the resin cement Variolink II was used, the types of root canal filling materials and sealers could affect the retentions of the fiber/zirconium posts; the fiber post revealed the higher bond values than the zirconium post; and the calcium silicate-based sealer (iRoot SP) revealed the highest bond strengths.     

Cadmium and lead contamination in vegetables collected from industrial, traffic and rural areas in Bursa Province, Turkey

Cadmium and lead contamination of vegetables produced in rural areas of Bursa Province, Turkey, was found to be less contaminated than vegetables grown close to heavy traffic and industrial activities. The highest levels of cadmium and lead were found in lettuce; the lowest levels in vegetables were found in leeks. The lead levels in spinach grown in traffic areas were at least twofold higher than those found in industrial areas. For other vegetables, the results from industrial and traffic areas were almost identical. Lettuce grown in traffic areas had the highest amount of cadmium (0.81 +/- 0.25 mg kg(-1)) and lead (1.59 +/- 0.45 mg kg(-1)), whilst leeks grown in rural areas had the lowest levels of lead (0.10 +/- 0.03 mg kg(-1)) and cadmium (0.05 +/- 0.01 mg kg(-1)) compared with other vegetables. This study shows that people and animals living in the same area in Bursa are always exposed to metallic pollution and in turn the consumption of contaminated vegetables could lead to increased dietary intake.     

Polymer Film Supported Bimetallic Au–Ag Catalysts for Electrocatalytic Oxidation of Ammonia Borane in Alkaline Media

Nano-Micro Letters - Ammonia borane is widely used in most areas including fuel cell applications. The present paper describes electrochemical behavior of ammonia borane in alkaline media on the...     

Role of organic additives on non-aqueous tape casting of SiAlON ceramics

Suspensions consisting of precursor α/β SiAlON forming powders, azeotropic solvent mixture of 60 MEK/40E, dispersant, binder, and plasticizer were optimized for tape casting by rheological measurements and tape properties. Sodium tripolyphosphate (STPP) was introduced as a dispersant for low temperature applications of α/β-SiAlONs. Optimum STPP amount was determined as 0.012 g/m² (of the particle surface) for stable α/β-SiAlON suspensions. Different amounts of binder/plasticizer mixtures were added to the slurries and the effects on rheological and green tape properties were investigated. Green tapes with dibutyl phthalate (DBP), and plasticizer mixture, poly(ethylene glycol) (PEG) and DBP, exhibited centered cracks with high plasticity, on the other hand, polyvinyl butral (PVB) and PEG showed no crack but low plasticity. Therefore, many different parameters were found to be effective on final tape properties. In addition, tapes were prepared with 6 vol% PVB + PEG, sintered at 1800 °C for 2 h and exhibited almost 97%TD in room temperature applications of α/β SiAlONs.     

Determination of Drying Characteristics of Timber by Using Artificial Neural Networks and Mathematical Models

In this research, poplar and pine timbers have been dried in heat pump dryer functioning on the basis of 24-h operation. The change in weight in all of the timbers was followed in the drying chamber and drying stopped when the desired weight was achieved. Initial moisture content of the poplar timbers was 1.28 kg water/kg dry matter, and the moisture content was reduced to 0.15 kg water/kg dry matter moisture content in 70 h; the moisture content of the pine timbers, which was 0.60 kg water/kg dry matter, was reduced to the same amount in 50 h. Drying air temperature, relative humidity, and stack weight were measured and collected during drying and saved on a computer and analyzed afterwards. The moisture ratios were analyzed with Statgraphic computer program by using semitheoretical models and empirical values. Correlation and standard error of estimation (SEE) and R ² values were achieved.     

Energy Analysis of a New Design of a Photovoltaic Cell-Assisted Solar Dryer

In this study, a new type of solar dryer was designed and manufactured. This new solar dryer is composed of a heat pipe collector, a drying chamber, a load cell, an air circulation fan, photovoltaic cells (PvC), batteries, and halogen lamps. In this experimental study, tomatoes were used to test the drying process. The drying air was heated by the heat pipe collector and forced through the tomatoes by a blower fan during the daytime. The photovoltaic cells, which were used to run the fan, were also used to charge the batteries during the day. These charged batteries were used for running the halogen lamps during the night, when the halogen lamps were used to heat the drying-air-assisted photovoltaic cells. During the drying period, the drying air temperature, relative humidity, air flow rates, solar radiation, and loss of mass were measured in the solar dryer. Then, the measured data were used for energy analysis.     

The sensitivity and impact of dye structure and fibre micronaire on the increased dyeability of bioengineered cotton fibres

Previous research reported on a screening method to assess the functionalisation of bioengineered cotton fibres through the absorption of CI Acid Orange 7. The aim of the present paper is to extend this study to different dye classes. Thus the dye absorption of bioengineered cotton fibres containing oligochitin is studied for a series of dye classes. Statistically significant differences were found between cotton lines designed to produce oligochitin in the fibre and their respective controls for all tested dyes, confirming previous results with CI Acid Orange 7. Further, although variations in micronaire influenced dye absorption, it was confirmed for all dyes tested as well as for CI Acid Orange 7 that the oligochitin production had a larger impact on the exhaustion values than the differences in micronaire. The method described in this paper can be applied as a screening tool to meet the challenge of working with small quantities of fibrous materials. Moreover it shows the potential that the incorporated oligochitin has for increasing dyeability with a wide range of dyes and creating fibres with more versatile reactivity.     

Combustion characteristics of cellulosic loose fibres

The aim of this paper is to study the combustion characteristics of loose fibrous cellulosic compounds through cone calorimeter measurements. The challenge in studying loose fibrous materials by cone calorimeter in a reproducible manner is met by optimizing various process parameters such as sample weight, heat flux and grid type. The method is validated using cotton fibres and fabrics with a range of flame retardant properties. Good correlations are obtained between the flame retardant content of samples and the heat release parameters for both the fibres and the fabrics. In addition, fibres from specific cotton cultivars showed statistically significant differences in heat release characteristics. This shows that valuable data concerning the combustion behaviour and the corresponding kinetics of loose fibrous compounds can be successfully gathered using a cone calorimeter. Thus, such data can be exploited to well define future fibre breeding programmes or fibre modification research. Copyright © 2012 John Wiley & Sons, Ltd.     

Effect of side chain substituents on the electron injection abilities of unsymmetrical perylene diimide dyes

Three near-infrared (NIR) absorbing unsymmetrical perylene diimide D-A-D type dyes containing 6-undecanoxy as donor group were utilized in dye-sensitized nanocrystalline TiO₂ solar cells. Structure of the acceptor side of the molecules were improved by adding 4-[2-methyl-5-(cyanoacrylic acid)-3-thienyl]-phenyl (V), 3-carboxy-2-pyridil (VI) and 3-carboxy-2-pyrazyl (VII) moieties attached to one of the N-side of the dye. The relationship between the molecular structure of the acceptor sites of the dyes and the photovoltaic performances were discussed. Electrochemical measurements indicated that band gaps of the dyes were energetically favorable for electron injection from the excited state of the dyes to the conduction band of TiO₂ nanoparticles. However, three dyes gave lower conversion efficiency on DSSC applications. Strong electron-withdrawing nature of perylene core might not permit to transfer the photo-generated electrons to the carboxyl groups anchoring to TiO₂ surface, and then solar-to-electricity conversion efficiencies of the dyes were reduced.     

Kinetic study of the thermal decomposition of (2‐phenyl‐1,3‐dioxolane‐4‐yl) methyl methacrylate and 2‐hydroxyethyl methacrylate copolymers

The kinetics of nonisothermal decomposition of (2‐phenyl‐1,3‐dioxolane‐4‐yl) methyl methacrylate (PDMMA), 2‐hydroxyethyl methacrylate (HEMA), and vinyl‐pyrrolidone (VPy) copolymers were investigated by thermogravimetry (TG) and differential thermal analysis (DTA). The data indicated that the major weight loss occurs in the range of 270 to 450°C. The decomposition characteristics showed essentially two regimes and varied depending on the temperature and the copolymer composition. The apparent kinetic parameters of the decompositions were estimated from both TG and DTA data by using the alternative calculation methods. The results suggest that the weight loss rates may be represented, depending on the type of sample, by a reaction model of overall order 1.0 to 1.6, with an activation energy of approximately 65–95 kJ mol^?1. The DTA data estimated considerably higher values for the overall activation energies, around 198–240 kJ mol^?1. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 95: 1500–1508, 2005