In this study, pristine TV-CRT screen glass (TVS) and those doped with 10% (TVS-Bi10) and 20% (TVS-Bi20) by weight of Bi2O3 were prepared and analyzed for their physical, microstructural, radiation ...dosimetry quantities, and shielding features. The glass samples were fabricated using the cold isostatic press method. The surface microstructure and the chemical composition of the glass ceramics were probed with the aid of the scanning electron microscopy-energy dispersive X-ray (SEM-EDX) system. Photon absorption and scattering quantities were estimated using standard procedures. The mean density values determined by Archimedes principle were calculated as 2.614, 2.788, and 3.056 gr/cm3 for the TVS, TVS-Bi10, and TVS-Bi20 samples, respectively. SEM images of samples showed that the increase in bismuth content increased sample crystallization and surface pores. The estimated mass energy absorption coefficients of the samples varied from 0.0177 to 11.7578 cm2/g for TVS, 0.0182–14.5218 cm2/g for TVS-Bi10, and 0.0187–17.7615 cm2/g for TVS-Bi20 for photon energies between 15 keV and 15 MeV. At 1 mm glass thickness and for 100 keV gamma rays, the dose rate was 13 MR/h, 17 MR/h, and 22 MR/h for TVS, TVS-Bi10, and TVS-Bi20, respectively. The mass stopping powers of electrons at 15 keV have values of 12.37 MeV cm2/g 12.21 MeV cm2/g, and 12.03 MeV cm2/g for TVS, TVS-Bi10, and TVS-Bi20, respectively. Generally, the ranges of the CPs were such that those of TVS > TVS-Bi10>TVS-Bi20. Bi2O3 increases the electron, proton, alpha particle, and carbon ion absorbing features of the TVS-BiX samples. Bi2O3 suppresses photon scattering, makes the TVS glass more sensitive to photon and charged particle interaction and absorption. The investigated glasses are useful for gamma-radiation, light, and heavy ion absorption and protection technology.
This study investigates the structural, mechanical, and gamma shielding features of glass samples with the composition 9Na2O-5BaO-Fe2O3-25Bi2O3-40B2O3 -(20-x)SiO2-xMgO (where x = 0 (G), 4 (GMgO4), 8 ...(GMgO8) and 12 (GMgO12) mol%). The glasses were prepared using the melt-and-quench method with the aim of characterizing them for radiation shielding and other relevant applications. The influence of MgO on the structure, density, hardness, and brittleness of the glass system was also investigated. The glassy nature of the prepared glasses was confirmed with the aid of a X-ray diffractometer. The mass attenuation coefficients (MACs) of the investigated glass samples were computed from data from FLUKA Monte Carlo simulations and XCOM datasets. The densities of the glasses varied from 2.98 gcm−3 (for G) to 3.18 gcm−3 for (GMgO12). The values of the hardness for the G, GMgO4, GMgO8, and GMgO12 samples are 4.28, 5.13, 5.51, and 5.79 GPa, respectively. The corresponding values of the brittleness are 2.81, 3.46, 3.76, and 4.10 (µ.m)−0.5. In addition, the fracture toughness declined from 1.66 MPa.m−0.5 for G to 1.39 MPa.m−0.5 for GMgO12. The values of the MAC for G, GMgO4, GMgO8, and GMgO12 vary from 0.0374 to 74.4652 cm2/g, 0.0375–74.9213 cm2/g, 0.0375–75.2458 cm2/g, 0.0376–75.5835 cm2/g, respectively. Also, the half-value layers ranging from 0.0031 to 6.2169 cm, 0.0031–6.1428 cm, 0.0030–5.9968 cm, and 0.0030–5.8017 cm were obtained for G, GMgO4, GMgO8, and GMgO12, respectively. The photon shielding abilities of the glasses trended in the following order: G < GMgO4 < GMgO8 < GMgO12. The GMgO12 glass showed a better gamma photon absorption capacity in contrast to conventional and nontraditional shielding materials. The optical transparency of the investigated glasses makes them more versatile in radiation shielding applications.
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Using computer-based simulation systems in medical education is becoming more and more common. Although the benefits of practicing with these systems in medical education have been demonstrated, ...advantages of using computer-based simulation in emergency medicine education are less validated. The aim of the present study was to assess the success rates of final year medical students in doing emergency medical treatment and evaluating the effectiveness of computer-based simulation training in improving final year medical students' knowledge.
Twenty four Students trained with computer-based simulation and completed at least 4 hours of simulation-based education between the dates Feb 1, 2010 - May 1, 2010. Also a control group (traditionally trained, n =24) was chosen. After the end of training, students completed an examination about 5 randomized medical simulation cases.
In 5 cases, an average of 3.9 correct medical approaches carried out by computer-based simulation trained students, an average of 2.8 correct medical approaches carried out by traditionally trained group (t = 3.90, p < 0.005). We found that the success of students trained with simulation training in cases which required complicated medical approach, was statistically higher than the ones who didn't take simulation training (p ≤ 0.05).
Computer-based simulation training would be significantly effective in learning of medical treatment algorithms. We thought that these programs can improve the success rate of students especially in doing adequate medical approach to complex emergency cases.
The dental implant is in contact with different tissue and bone types throughout the area where it is placed. In this study, a functional grade implant sample was designed considering these change ...zones. The part inside the jawbone was made of silver-coated porous titanium-(10 wt%)hydroxyapatite, while the amount corresponding to the gingiva was made of pure dense titanium. The titanium-(10 wt%)hydroxyapatite fraction was obtained with a porosity of approximately 62% and a density of 1.63 g/cm3. In addition, the elastic modulus of this region was calculated as an average of 12 GPa. These values are consistent with those of cortical bone. Apatite particles deposited after soaking in simulated body fluid are evidence of high biocompatibility. The compressive strength of the functionally graded sample was found to be approximately 35 MPa, which is sufficient to withstand the chewing forces by a large diameter dental implant. In addition, antibacterial properties were provided by the deposition of silver particles on the surface of the porous titanium-(10 wt%)hydroxyapatite. This new biosample, a functionally graded composite, has shown promising results for dental implants.
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•A new functional grade dental implant specimen was designed.•The porous Ti10HA fraction showed good bioproperties and biocompatibility.•Silver coating on the porous surface provides antibacterial properties.•The compressive strength of functional grade material meets occlusion forces.
This work was focused primarily on the investigation of the parameters effecting the formation of β-SiC and their crystallite diameter. Previous works revealed that the preparation of silica used as ...a precursor was the key factor on the resulting particle features. Therefore, the work aimed to achieve obtaining ultrafine silica precursor with superfine crystallites at relatively low temperatures. In the result, a clear difference was observed between the finally obtained SiC powders in terms of conversion and particle morphology according to the preparation process. The use of a modified high energy ball milling system resulted in a considerable reduction in the size of the starting particle's diameter (>100 nm). The FTIR transmission spectra of the yielded nanowires confirmed the SiC composition with the peak near 950 cm−1, which represents the LO stretching Si–C bond. The precursor preparation process improved the efficiency of Carbothermic Reduction and Carburization process used in the synthesis of SiC nanowires. The XRD findings indicated that all the precursors consisted of only amorphous silica, and the modified high energy ball milling system thermodynamically supported the crystal to amorphous conversion. The SEM micrographs revealed that the SiC nanowires had diameters of 50–100 nm with hundreds of microns in length. The SiC nanowire composed of ultrafine crystalline cubic SiC in beta form. As a result, the silica conversion to silicon carbide was successfully completed at a faster reduction rate and relative lower temperature (1475 °C for 4 h).
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•Ultra-fine β-SiC nanowires were synthesized via a carbothermic reduction–carburization process.•Improvement in the efficiency of the processes was achieved by a mechanochemical preparation.•The synthesis reactions were carried out at relatively low temperatures.•Monophasic β-SiC powder was successfully synthesized at 1475 °C for 4 h.•The SiC superfine crystallites with 50–100 nm in diameter were obtained.
For implants that can be used instead of bone, a porous chitosan/carbon nanotube biocomposite coating on the titanium surface was produced by the spacer holder method. Different chemical contents and ...varying amounts of space-holding material were studied. Carbon nanotube fibers and pore distributions are homogeneously dispersed in the biopolymer chitosan matrix. NaCl was used as a space holder, and the rate of space holder was increased by 90 % to obtain a trabecular bone-like structure successfully. By increasing the amount of spacer in the coating content from 0.45 g to 0.90 g, the pore size has reached from approximately 1–3 μm to 12 μm. XRD, FTIR, and Raman analysis interpreted the characterization of the coatings. With the addition of carbon nanotubes to the chitosan matrix coating, the stiffness and elastic modulus increased by 55 % and 80 %, respectively. The elastic modulus (12 GPa) of the chitosan/carbon nanotube composite coating is compatible with that of cortical bone. The surface roughness of the chitosan/carbon nanotube coating reached from 1 to 6 μm to 6–16 μm, forming a porous structure. The surface properties of the porous biocomposite coating are promising for orthopedic implant applications.
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•CNT fibers with a diameter of 180 nm were dispersed in the CHI-based matrix.•Interconnected pores and network morphology of approximately 1–12 μm were obtained.•The roughness obtained in the 1–12 μm, is suitable for bone-implant contact.•Elastic modulus of the CHI/CNT coating is compatible with cortical bone.
In the study, core-shell-structured Al/(ZnO:rGO)/pSi/Al photo-diodes were successfully fabricated using a sol-gel spin-coating method by varying the concentration of reduced-graphene oxide (rGO) from ...1 % to 9 % (wt). The ZnO:rGO composite solution was coated on a silicon (p-Si) wafer at 1000 rpm and 300 K. Both aluminum back-ohmic and front-rectifier contacts were performed on the p-Si wafer by physical-vapor-deposition (PVD). The morphological and chemical structure of the photo-diodes were determined by using field-emission scanning electron microscopy (FE-SEM), energy dispersive spectrometry (EDS), and X-ray diffraction (XRD). The current-voltage (I-V) analysis in dark and under ultraviolet (UV, 365 nm) wavelength was utilized in detail. Basic electrical parameters, including the ideality factor (n), barrier height (BH) and series-shunt resistances (Rs, Rsh), were calculated using a variety of methods and compared to each other. The Card-Rhoderick method was used to extract energy-dependent profiles of interface traps (Nss). The core-shell-structured (ZnO-7 % rGO) photo-diode exhibited the best photocatalytic performance both in dark and under various illumination intensities (50–250 mW/cm2). The ZnO:rGO interlayer at the metal-semiconductor (M/S) interface leads to improvement of the photo-diode in respect of low-ideality factor/Nss/leakage-current and high-rectification and BH.
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•The ZnO:rGO core-shell structures were synthesized and coated successfully and homogeneously using sol-gel spin coating.•This study is pioneer due to the fact that there is no detailed study about the Al/ZnO:rGO/pSi/Al photo-diodes from ZnO:rGO interface as wrapped different rGO rates ZnO core-shell.•The rGO nanosheets were provided bridging and this may be a conductivity mechanism between ZnO spheres that increases the conductivity of the photo-diodes.•The 7 % rGO included ZnO core-shell structure has a strongly positive effect on the photo-diode performance.•The 7 % rGO included ZnO:rGO interlayer can be succesfully used instead of traditional insulator layer in the future.
Metallic titanium (Ti) implant surfaces need improvement for bioproperties and antibacterial behavior. For this purpose, a new boron-doped bioactive apatite–wollastonite (AW) coating was successfully ...developed on the Ti plate surface. The effects of boron addition on the microstructure, mechanical properties, and bioproperties of the AW coating were investigated. With the addition of boron (B), the AW coating morphology became less porous and compact. In terms of bio properties, the rate of apatite formation increased with the addition of B, and the cell viability rate increased from approximately 66–81%. B addition increased the elastic modulus of the AW coating from about 24–46 GPa and increased its hardness about 2.5 times. In addition, while no antibacterial activity was observed in the AW coating, the addition of boron slightly introduced antibacterial properties. The novel AW/B composite coating obtained is promising for Ti implant surfaces.
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In the study, the fabrication processes of the Al/p-Si (MS), Al/ZnO/p-Si (MIS1), and Al/(ZnO:Si3N4)/p-Si (MIS2) structures were described and the effect of the ZnO:Si3N4 interface layer in MS was ...investigated in detail. The ZnO and (ZnO:Si3N4) thin films were coated on p-Si substrates and annealed at 500 °C for 1 h. Si3N4 and ZnO phases were identified via X-ray diffraction (XRD) and Raman spectra. FESEM images demonstrated that ZnO nanorods grew on Si3N4 particles with a heterogeneous nucleation mechanism. The I–V characterization was performed in the dark (±4 V). The basic diode parameters (barrier height (BH), series/shunt (Rs/Rsh) resistances, rectifying rate (RR=If/Ir), and ideality factor (n)) were calculated from various methods. The RR, and Rsh values increased, but n, Rs and BH decreased by insulating layer in the MIS2 The energy-dependent profiles of interface-states (Nss) were also extracted from the I–V plots according to voltage-dependent n and BH. The MIS2 provided the best passivation effect with decreasing interface traps.
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F0B7The ZnO:Si3N4 nanofilms were successfully synthesized by sol-gel routes.F0B7The Si3N4 included ZnO:Si3N4 interface has had the potential for insulating layer.F0B7Interface-states were decreased with doping of the Si3N4 into ZnO with the help of reconstruction of microstructure.F0B7The Si3N4 within ZnO has had a good passivation effect on interface traps.
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