Turkish Paediatric Dentists’ Knowledge, Experiences and Attitudes Regarding Child Physical Abuse

Objectives Numerous studies have shown that the education of health professionals is essential to effectively respond to child abuse. The present study aimed to evaluate Turkish paediatric dentists\u27 knowledge, experiences and attitudes regarding child physical abuse. Materials and methods An electronic questionnaire was e‐mailed to 518 paediatric dentists. Participants’ knowledge of diagnostic indicators of child physical abuse, and their past experiences, attitudes and self‐assessment of educational needs were evaluated. Results The response rate was 40.9% (n = 212). Participants who completed their undergraduate education before 1997 received significantly less education on child physical abuse than participants who completed their education more recently (P \u3c 0.001). Although statistically insignificant, participants who completed their doctorate/specialty training after 2012 received increased education on child physical abuse (P = 0.06). Of the participants, 43.9% suspected physical abuse; however, only 12.7% reported it. ‘I did not know where and how to report’ was the most common reason for not reporting physical abuse. The rate of suspicion was higher among dentists from state hospitals or oral health centres (P \u3c 0.05). Of the participants, 70.3% did not know about the legal sanctions for delay in or not reporting suspected cases. Only 15.6% assessed themselves as competent to diagnose and report physical abuse. Almost all of them acknowledged their need for more education on this topic. Conclusion Turkish paediatric dentists’ educational needs for diagnosing and reporting of child physical abuse cases should be met

Thermoelectric enhancement in PbTe with K, Na co-doping from tuning the interaction of the light and heavy hole valence bands

The effect of K and K-Na substitution for Pb atoms in the rock salt lattice of PbTe was investigated to test a hypothesis for development of resonant states in the valence band that may enhance the thermoelectric power. We combined high temperature Hall-effect, electrical conductivity and thermal conductivity measurements to show that K-Na co-doping do not form resonance states but2 can control the energy difference of the maxima of the two primary valence sub-bands in PbTe. This leads to an enhanced interband interaction with rising temperature and a significant rise in the thermoelectric figure of merit of p-type PbTe. The experimental data can be explained by a combination of a single and two-band model for the valence band of PbTe depending on hole density that varies in the range of 1-15 x 10^19 cm^-3.Comment: 8 figure

Promising bulk nanostructured Cu₂Se thermoelectrics via high throughput and rapid chemical synthesis

A facile and high yield synthesis route was developed for the fabrication of bulk nanostructured copper selenide (Cu2Se) with high thermoelectric efficiency. Starting from readily available precursor materials and by means of rapid and energy-efficient microwave-assisted thermolysis, nanopowders of Cu2Se were synthesized. Powder samples and compacted pellets have been characterized in detail for their structural, microstructural and transport properties. alpha to beta phase transition of Cu2Se was confirmed using temperature dependent X-ray powder diffraction and differential scanning calorimetry analyses. Scanning electron microscopy analysis reveals the presence of secondary globular nanostructures in the order of 200 nm consisting of <50 nm primary particles. High resolution transmission electron microscopy analysis confirmed the highly crystalline nature of the primary particles with irregular truncated morphology. Through a detailed investigation of different parameters in the compaction process, such as applied load, heating rate, and cooling profiles, pellets with preserved nanostructured grains were obtained. An applied load during the controlled cooling profile was demonstrated to have a big impact on the final thermoelectric efficiency of the consolidated pellets. A very high thermoelectric figure of merit (ZT) above 2 was obtained at 900 K for SPS-compacted Cu2Se nanopowders in the absence of the applied load during the controlled cooling step. The obtained ZT exceeds the state of the art in the temperature ranges above phase transition, approaching up to 25% improvement at 900 K. The results demonstrate the prominent improvement in ZT attributed both to the low thermal conductivity, as low as 0.38 W m(-1) K-1 at 900 K, and the enhancement in the power factor of nanostructured Cu2Se. The proposed synthesis scheme as well as the consolidation could lead to reliable production of large scale thermoelectric nanopowders for niche applications

The conductivity properties of TlBi(Se1-xSx)(2) crystals

In the past forty years we witnessed a tremendous progress in technology. Use of semiconductors in electronic industry has played an extremely important role in this. The remarkable physical properties like high conductivity, thermo-electric power and photosensitivity of layered single crystals, such as TlBiX2 (X = Se, S), have made possible their use in photocells, thermo-electric instruments, opto-acoustic detectors and circuit elements. In this work, we are trying to understand the conductivity properties of TlBi(Se1-x,S-x)(2) layered single crystals, for x = 0.0, 0.25, 0.50, 0.75 and 1.0, by studying their resistivity in the direction perpendicular to the crystal axis and thermo-electric properties in the 293-413 K temperature region. We thank to M. Ozer who provided us these crystals which were grown by Bridgman-Stockbarger method [1]

Thermoelectric properties and EPR analysis of Fe doped Cu12Sb4S13

Recently tetrahedrite compounds have attracted great attention due to their potential applications on the mid temperature thermoelectric technologies. In this work, structural, Electron Paramagnetic Resonance (EPR) and the thermoelectric properties of tetrahedrite (Cu12-xFexSb4Si13 where x = 0.0, 1.0, 1.5, 2.5) were investigated. The crystal structural, morphological properties and elemental compositions of the samples were investigated by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDS-EDX) tools respectively. Magnetic properties of the samples were performed by EPR techniques using electron spin resonance (ESR) spectrometer with the model of Bruker EMX series at X-band (9.5 GHz). The thermoelectric properties were assisted based on Seebeck coefficient, electrical resistivity, and thermal conductivity measurement between 300 and 600 K temperature range. PXRD patterns and SEM-EDX analysis confirmed the main phase of tetrahedrite structure for all compounds. The Seebeck coefficient sign indicated that holes were dominant carriers in all compounds. Electrical resistivity measurement showed an increment with increasing Fe concentration likely due to decreasing in carrier density. A typical behavior of intrinsic semiconductor was observed from temperature-dependent electrical resistivity measurements. The maximum ZT value of 0.6 was achieved for the sample Cu11Sb4S13 at 550 K. Electron Paramagnetic Resonance (EPR) and thermoelectric measurements exhibited that the maximum Fe concentration might be 5 1.0 for achieving high ZT value in Cu12-xFexSb4Si13 compounds

The Effect of Crystal Mismatch on the Thermoelectric Performance Enhancement of Nano Cu2Se

In the past decades, Cu2-x Se compounds have attracted great attention due to the inclusion of non-toxic and abundant elements, besides having a promising thermoelectric (TE) performance. In this work, we investigated the effect of a crystal mismatch of a nanoinclusion phase on the TE properties of Cu2-x Se. Nano-Cu2Se was synthesized using microwave assisted thermolysis, while the p-type skutterudite, Fe3.25Co0.75Sb12 (FeCoSb), compound was synthesized using a chemical alloying route. Nano-Cu2Se, and (nano-Cu2Se)(1-x )(nano-FeCoSb)( x ) composites, where x = 0.05 and 0.1, were prepared via mechanical alloying followed by Spark Plasma Sintering process. Structural properties were evaluated by PXRD and SEM analysis, while the high temperature transport properties were examined via electrical conductivity, Seebeck coefficient, and thermal conductivity measurements in the temperature range of 300-800 K. Powder X-ray diffraction (PXRD) confirmed a single phase of nano Cu2Se, while the samples with FeCoSb inclusion consist of two phases as Cu2Se and CoSb3. SEM micrographs of all samples show that Cu2Se has randomly oriented grains with different sizes. Cu2Se samples with a FeCoSb inclusion show a rather different structure. In these samples, a rod-shaped FeCoSb phase, with a size varying between 20 and 100 nm, showed an inhomogeneous distribution in the structure and stacked between the Cu2Se layers. Transport data indicate that crystal mismatch between Cu2Se and FeCoSb has a strong effect on the TE transport properties. Electrical conductivity decreases but Seebeck coefficient enhances with nano FeCoSb inclusion. Total thermal conductivity was suppressed by 30% and ZT value enhanced by 15% with 5% nano FeCoSb inclusion at 750 K, likely due to a decrease in the electronic contribution of the thermal conductivity. Structural and transport data show that small amount of nanoinclusion of FeCoSb has a beneficial effect on the TE performance of nano Cu2Se at temperatures below 800 K

Multi-objective optimization of concentrated Photovoltaic-Thermoelectric hybrid system via non-dominated sorting genetic algorithm (NSGA II)

Thermoelectric generators harvest additional electrical power when used in combination with concentrated photovoltaic cells given rise to a hybrid system. Overall cost of the system is high; therefore, the parameters of the system need to be optimized to obtain high output performance. This study determines the output performances of four sets of equations (models) used in the hybrid system, using the performance of recently developed nanostructured thermoelectric materials. Seven parameters of the system were optimized through these models using non-dominated genetic algorithm. Models 1 and 2 have the highest performance chosen by TOPSIS decision-making method. The power output and conversion efficiencies of the hybrid system in models 1 and 2 are 426.5 W, 11.45% and 461.12 W, 10.77%, respectively. Likewise, the highest TOPSIS solution for power output of one TEG module operating in the hybrid system and its corresponding efficiency is obtained in model 4 and are 1.97 W and 0.078%, respectively. This validates the fact that TEG operating in a hybrid system has optimum performance at a point when the load resistance is less than its internal resistance