Kitsakorn Locharoenrat

Design and Fabrication of Gamma-Type Stirling Engine on Parabolic Dish of Solar Concentrator by a Compression Ratio Method

In this article, we have designed and fabricated the gamma-type Stirling engine based on the compression ratio technique. This engine is attached on a parabolic dish of a solar collector. The engine shows a good performance in terms of compression ratio, external work, total pressure, and engine’s speed. Our engine offers the thermal efficiency of 30.59 % so that it can reach the output mechanical power of 0.934. The temperature difference of 137 K can maintain very well for the heat collection of the solar collector even when the weather conditions are poor. Furthermore, our materials are environmentally friendly and this design is expected to be in the applications of the solar tracker in the future.

Recent Trend of Solar Tracking System for Electric Power Conversion

In this article, we simply design the solar tracking system and construct a solar collector system for year 2015 in Bangkok, Thailand. The analytical model is calculated via altitudes and azimuth angles of the sun. Our experimental result is agreement well with the calculation in terms of altitude and azimuth. This solar tracking system is therefore applied to a dish solar collector showing the thermal energy of 961.69 W at a maximum temperature of 543.3K with a maximum electric power of 3.395W from our thermoelectric modules.

Preparations and Field Emission from Tungsten Nanotips

We have presented a simple method to prepare tungsten nanotips. The method was based on a “drop-off” method, in which the tip was continuously and slowly drawn up from the electrolyte during etching. We then observed the field emission current with respect to the applied voltage from the fabricated tip with and without the irradiation of 20 fs laser pulses at a wavelength of 800 nm. The tips showed good field-emission properties as revealed by the current-voltage characteristics and analyzed based on the Fowler–Nordheim (F-N) theory. The turn-on field was 5 V/μm to achieve a current density of 500 A/m2, whilst the local electric field strength at the tip was equal to 2 V/nm. Together with their ease of preparation, these tips were shown to have great potential in the area of electron field-emitting devices.

Characterization, Optical, and Theoretical Investigation of Arrays of the Metallic Nanowires Fabricated by a Shadow Deposition Method

We have fabricated Au, Cu, and Pt nanowires by using a shadow deposition technique. We have then investigated optical properties of these nanowires by studying the second harmonic generation (SHG) spectra. With experimental and theoretical studies, we have discovered that the surface plasmon resonance was served as an origin of the enhancement of the SH response from the metallic nanowires.

Effects of Gold Nanoparticles on Fluorescence Polarization and Emission Spectra of Rhodamine 6G Solution

Fluorescence polarization and emission spectra of Rhodamine 6G solution with gold nanoparticles have been studied. It is found that the emission intensities tend to be low when the gold nanoparticles are added into the solution partly due to the energy transfer from the Rhodamine 6G to gold nanoparticles. The fluorescence polarization increases as the concentration ratio of the gold and Rhodamine 6G is more than 124 and decreases as the ratio is about 1115. The enhancement and reduction of fluorescence polarization values are understood as the shortening of the fluorescence lifetime and a temperature effect from the heating of gold nanoparticles, respectively.

Studies of concentration dependence of the fluorescent quantum yield from rhodamine 6G and AuPd coreshell nanorods, using a response surface methodology

We have applied a response surface approach to study the fluorescence quantum yield (FQY) of rhodamine 6G (Rh6G) mixed with Au–Pd core–shell nanorods (Au–Pd NRs). The FQYs have been measured for the Rh6G concentrations varying from 3.53×10 to 1.70×10 mol/L and the concentrations of Au–Pd NRs from 7.06×10 to 1.36×10 mol/L. Our experimental results testify that the FQY depends notably on the proportions of Rh6G and Au–Pd NRs. A specific relationship between the FQY and the concentrations has also been confirmed by a response surface plot. It is found that the discrepancy between the experiment and the calculations is less than 2%.

Calculation of Lead-Iron Double-Layer Thickness for Gamma-Ray Shielding by MATLAB Program

This contribution is aimed at designing the optimal thickness of lead-iron double-layer container to store a radioactive waste releasing the photon energy at 1.3325 MeV and initial radiation intensity at 100 mSv/hr using the optimization design by MATLAB software. This design consisted of three parts of calculations to achieve 1000 times the radiation attenuation of container. The first was the logarithmic interpolation for the mass attenuation coefficient. The second was the bilogarithmic interpolation for the exposure buildup factor. The third was the contour-plotting analytical technique for the optimal thickness of radiation container. The values of mass attenuation coefficient and exposure buildup factor were exactly validated as compared with the standard reference database. Furthermore, we have found that the optimal thickness was 3.2 cm for lead (1st layer) and 17.0 cm for iron (2nd layer). Container weight was 994.30 kg, whilst container cost was 167.30 USD. The benefit of our design can quickly and precisely apply for the radiation safety assessment of the occupational radiation workers who always work in the nuclear reactor area.

Characteristic Evaluation of Organic Light-Emitting Diodes Prepared with Stamp Printing Technique

We have reported on a stamp printing technique that uses PET release film as a printing stamp to deposit TPBi thin film served as the electron transport layer of the organic light-emitting diodes. TPBi thin film was printed with a good uniformity and resolution. Effect of deposition conditions on optical and electrical properties and surface roughness of TPBi thin film have been studied under spectroscopy and atomic force microscopy, respectively. It is found that characteristic of TPBi thin film is improved via controlled stamp temperature and time. Since TPBi thin film exhibits the surface morphology comparable to that of conventional spin-coating thin film, our findings suggest that PET release film-based stamp printing approach is possible to use as an alternative deposition of the organic thin film as compared with a traditional one.

Photocatalytic Effect of Metal Oxide Nanoparticles on Cultured Human Breast Cancer Cells

We have studied the photocatalytic effect of ZnO, TiO2 and CuO nanoparticles under the different wavelength of the light irradiation on the cultured human breast cancer cell line. Each nanoparticle under the different wavelength of irradiation on the cells shows the different cell-killing effect. It is found that ZnO nanoparticles irradiated under the ultraviolet C are more pronounced toxicity than CuO nanoparticles irradiated under the visible light, and TiO2 nanoparticles irradiated under the ultraviolet A, respectively. The intimate contact between the cell wall and the metal oxide nanoparticles under the appropriate light irradiation causes the changes in the environment in the vicinity of cell-nanoparticles contact area. This can generate the intracellular reactive oxidation species, partly due to the electron-hole pair, that tends to damage the nucleus of the cancer cells.

Comparison of Fluorescence Behaviors of Rhodamine 6G with Palladium-Coated Gold Nanorods in Formations of Solutions and Thin Films

We have reported on the fluorescence behaviors of Rhodamine 6G with the palladium-coat gold nanorods in dichlormethane solution and in polymethylmethaceylate thin film. By monitoring the emission intensity of these samples, they show the enhancement of fluorescence intensity through the optical effect known as a plasmon resonance energy transfer. The enhancement intensity of fluorescence is enhanced up to 1.6 fold for the sample solution and 1.4 fold for the sample thin film.