Characterization and thermoluminescence behavior of beta irradiated NaBaBO3 phosphor synthesized by combustion method

NaBaBO₃ host material was synthesized using the combustion method. In order to optimize the performance of the material, effects of sintering temperatures varying from 600° to 1000?°C were investigated. The sintering temperature and dwell time were found to have pronounced effects on the pure NaBaBO₃ material. X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) techniques were used to confirm the phase formation and examine the surface morphology of the prepared powder material, respectively. TL behavior of NaBaBO₃ was studied at various beta doses. It is seen that the sample exhibits well resolved TL glow peak at a peak temperature about 175?°C and corresponding TL intensity increases with the increasing beta dose. However, TL glow peak slightly shifts to lower temperature with the increasing beta dose level. This is the first TL report of a phosphor with a NaBaBO₃ host. The TL kinetic parameters were estimated by the peak shape (PS) method and CGCD software. TL glow curves of NaBaBO₃ consist of several traps and exhibited second order kinetics. A possible TL mechanism was also discussed using the energy level model. The obtained results can provide valuable knowledge related to the investigation of the intrinsic nature characteristics of NaBaBO₃ in research fields pertaining to dosimetry.     

Self-limiting low-temperature growth of crystalline AlN thin films by plasma-enhanced atomic layer deposition

We report on the self-limiting growth and characterization of aluminum nitride (AlN) thin films. AlN films were deposited by plasma-enhanced atomic layer deposition on various substrates using trimethylaluminum (TMA) and ammonia (NH₃). At 185 °C, deposition rate saturated for TMA and NH₃ doses starting from 0.05 and 40 s, respectively. Saturative surface reactions between TMA and NH₃ resulted in a constant growth rate of ~ 0.86 Å/cycle from 100 to 200 °C. Within this temperature range, film thickness increased linearly with the number of deposition cycles. At higher temperatures (≥ 225 °C) deposition rate increased with temperature. Chemical composition and bonding states of the films deposited at 185 °C were investigated by X-ray photoelectron spectroscopy. High resolution Al 2p and N 1s spectra confirmed the presence of AlN with peaks located at 73.02 and 396.07 eV, respectively. Films deposited at 185 °C were polycrystalline with a hexagonal wurtzite structure regardless of the substrate selection as determined by grazing incidence X-ray diffraction. High-resolution transmission electron microscopy images of the AlN thin films deposited on Si (100) and glass substrates revealed a microstructure consisting of nanometer sized crystallites. Films exhibited an optical band edge at ~ 5.8 eV and an optical transmittance of > 95% in the visible region of the spectrum.     

Effect of Titanium additive element on the discharging behavior of MgNi Alloy electrode

Mg_0.90Ti_0.10Ni, Mg_0.85Ti_0.15Ni, Mg_0.80Ti_0.20Ni, Mg_0.90Ti_0.15Ni_0.95, Mg_0.90Ti_0.20Ni_0.90 and Mg_0.95Ti_0.15Ni_0.90 ternary alloys were synthesized by mechanical alloying and their electrochemical hydrogen storage characteristics were investigated. Among the Mg-Ti-Ni ternary alloys Mg_0.90Ti_0.20Ni_0.90 alloy showed the best discharge performance. The initial discharge capacity was observed to depend on Mg/Ni atomic ratio rather than Ti/Mg atomic ratio in alloys. As the Ti/Mg atomic ratio increased the alloy charge transfer resistances decreased probably due to the partial selective dissolution of the surface Ti/Ti-oxides and thus the limited enrichment of the surface by the electro-catalytic Ni. The average hydrogen diffusion coefficients in all the Ti-including alloys were higher than that in MgNi alloy. The increase in Ti/Mg atomic ratio, however, did not cause any further increase in the average hydrogen diffusion coefficient.     

Experimental analysis of the effects of hydrogen addition on methane combustion

This paper presents gas emissions from turbulent chemical flow inside a model combustor, for different blending ratios of hydrogen–methane composite fuels. Gas emissions such as CO and O₂ from the combustion reaction were obtained using a gas analyzer. NOx emissions were measured with a NOx analyzer. The previously obtained flame temperature distributions were also presented. As the amount of hydrogen in the mixture increases, more hydrogen is involved in the combustion reaction, and more heat is released, and the higher temperature levels are resulted. The results have shown that the combustion efficiency increases and CO emission decreases when the hydrogen content is increased in blending fuel. It is also shown that the hydrogen–methane blending fuels are efficiently used without any important modification in the natural gas burner. Copyright © 2011 John Wiley & Sons, Ltd.     

Can Dentin Surfaces Be Bonded Safely With Ozone and Boric Acid?

The aim of this study is to evaluate the effect of different cavity disinfectants on shear bond strength. In this study, 60 caries-free human molar teeth were used. Smooth dentin surfaces were revealed by cutting occlusal enamel and a standard smear layer was obtained by using 600-grid sandpaper. Specimens were randomly assigned to four groups according to the disinfectant used: Group 1: Control (no disinfectant); Group 2: Ozone; Group 3: Chlorhexidine, Group 4: Boric acid. Specimens were bonded using S3 Plus Bond and the composite buildups were created by using composite resin according to the manufacturer’s instructions. After specimens were kept for 24 h, at 37 °C in distilled water, the shear bond strength test was measured with a universal test machine. The highest bond strength values were observed in the control group. The bond strength was significantly lower in the chlorhexidine, and boric acid-treated groups than it was in the control group (respectively, p = 0.046 and p = 0.028); however, no significant difference in the bond strength was observed between the ozone group and the control group (p = 0.444). The ozone group was detected as having the best shear bond strength values in groups which were applied to cavity disinfectants.     

Experimental analysis and CFD simulation of infrared apricot dryer with heat recovery

Drying is one of the easily accessible and the most widespread processing technologies that have been used since ancient times for preserving fruits. Drying is an energy-intensive and time-consuming process, so reducing energy demand is important. The main aim of this paper is to analyze the heat and mass transfer characteristics of product in the drying chamber and in addition to this, three-dimensional (3-D) computational fluid dynamic (CFD) simulation was performed. The analyses of heat and mass transfer were investigated theoretically and experimentally in infrared dryer (IRD). The dryer consists of air to air heat recovery unit and proportional temperature controller. Experiments were performed at 0.5 and 0.25?m/s air velocities and at 60 and 65°C apricot surface temperatures which were controlled by three thermocouples contacted on top side of the product. In order to use energy more effectively and improve the drying characteristics of apricot, analyses were performed under different drying conditions. Since the heat recovery unit has a key role in this system, the performance of this unit was investigated and recovered energy ratio was between 58 and 62%. The calculated moisture diffusivity values varied from 1.7?×?10^?10 to 1.15?×?10^?9 for apricot, and the highest value of average energy efficiency was obtained as 16.43% at 65°C temperature and 0.25?m/s air velocity. Theoretical and experimental results are in line with each other.     

ANN Analysis of a Roller Compaction Process in the Pharmaceutical Industry

Dry granulation via a roller compactor was simulated based on the artificial neural network (ANN) methodology. Two process parameters, including roll force and screw speed, were considered as input of the simulation whereas ribbon density was considered as output. Experimental work was carried out using an industrial‐scale roller compactor. The results showed an excellent agreement between simulation and experiments. The findings were compared as well with the results obtained in a previous study employing the Johanson model, which is the predominant model for the simulation of a roller compaction process. The overall deviation observed for the developed ANN model was found to be significantly improved in comparison with the deviation obtained for the Johanson model. The results demonstrated a very good capability and robustness of the developed ANN model in design and optimization of the roller compaction process.     

Dihydropyridine derivatives as controllers for production of hydrogen during zinc dissolution

Two of dihydropyridine derivatives, namely, 4,6-dimethyl-2-oxo-1,2-dihydropyridine-3-carbonitrile (DPCN) and 4,6-dimethyl-2-oxo-1,2-dihydropyridine-3-carboxamide (DPCA) were evaluated as controllers for H₂ production during the dissolution of Zn in dilute HCl. Different chemical (thermometry, gravimetry, and gasometry) and electrochemical (potentiodynamic polarization and impedance) techniques were used. SEM and optical profilometry surface investigations for some corroded and un-corroded Zn samples were carried out to describe the Zn surface during the dissolution process. The rate of H₂ production was found to increase with the immersion time and temperature and was lowered by the inhibitor. The potentiodynamic data proved that DPCN and DPCA inhibit the dissolution of Zn according to a mixed-type mechanism.