A new liquid crystal color calibration technique using neural networks and median filtering

This study has developed a new liquid crystal calibration technique using Neural networks with median filtering and applied this technique to heat transfer measurements. To verify the validity of this new measurement technique, the local Nusselt numbers on a flat plate surface subjected to an axisymmetric impinging jet were measured and compared with the results by the conventional Hue-temperature calibration technique under the same conditions. Because the Neural networks predict the non-linear relations between temperatures and corresponding R, G, B values, Neural networks-median filtering calibration technique can utilize a much wider color band in the experiment than the Hue-temperature calibration technique, resulting in a significant reduction in the experimental time.     

Photocatalytic activity of nanosized TiO2 thin film prepared by magnetron sputtering method

Nanosized TiO2 thin film on the substrate such as stainless steel plate and slide glass film were prepared by magnetron sputtering method, and these TiO2 thin films were characterized by field emission-scanning electron microscopy (FE-SEM). Photocatalytic activity for Methyl-ethyl-ketone (MEK) and acetaldehyde were measured using a closed circulating reaction system through the various ultra violet (UV) sources. From the results of SEM images, nanosized TiO2 thin film was uniformly coated on slide glass, ranging from 360 nm to 370 nm. Photocatalytic activity of MEK over TiO2 thin film on stainless steel plate did not occur by UV-A irradiation, but was efficiently decomposed by UV-B and UV-C. Also, acetaldehyde could be decomposed than MEK. The effect of sputtering conditions on their structure and photocatalytic activities were investigated in detail.     

Mitigating grain growth in fully stabilized zirconia via a two-step sintering strategy for esthetic dental restorations

Overall, 8-mol% yttria-stabilized zirconia (8YSZ), unlike 3YSZ, is optically transparent and stable against low-temperature degradation but has insufficient mechanical properties due to its large grain size. The influence of the grain size of 8YSZ on mechanical properties was investigated to develop an 8YSZ suitable for dental restoration. Modulation of the grain size and relative density was achieved via a two-step sintering (TSS) process, and the corresponding kinetic window was established. The conditions of TSS employed herein yielded a relative density of more than 99% while maintaining a small grain size of 0.75 µm. On the other hand, the highest biaxial strength and the highest total transmittance attained were 833 MPa and 34.6% (1-mm- thick, 39.1% for a 0.5-mm thick sample) in the TSS 8YSZ with a grain size of 1.25 µm. These results suggest that strength has improved only when grain size reduction and increased relative density are achieved at the same time. The results demonstrate that the ceramic processing method has a significant effect on the mechanical and optical properties of 8YSZ needed for dental restoration and provide a new insight that contrasts previous studies focused on the starting material.     

Characterization of intrinsic a-Si:H films prepared by inductively coupled plasma chemical vapor deposition for solar cell applications

The hydrogenated amorphous silicon (a-Si:H) films, which can be used as the passivation or absorption layer of solar cells, were prepared by inductively coupled plasma chemical vapor deposition (ICP-CVD) and their characteristics were studied. Deposition process of a-Si:H films was performed by varying the parameters, gas ratio (H2/SiH4), radio frequency (RF) power and substrate temperature, while a working pressure was fixed at 70 m Torr. Their characteristics were studied by measuring thickness, optical bandgap (eV), photosensitivity, bond structure and surface roughness. When the RF power and substrate temperature were 300 watt and 200 degrees C, respectively, optical bandgap and photosensitivity, similar to the intrinsic a-Si:H film, were obtained. The Si-H stretching mode at 2000 cm(-1), which means a good quality of films, was found at all conditions. Although the RF power increased up to 400 watt, average of surface roughness got better, compared to a-Si:H films deposited by the conventional PECVD method. These results show the potential for developing the solar cells using ICP-CVD, which have the relatively less damage of plasma.     

Compatibilization of PLA/starch composite with electron beam irradiation in the presence of a reactive compatibilizer

The aim of this study is to improve the compatibility of poly (lactic acid) (PLA)/starch composite by electron beam irradiation in the presence of glycidyl methacrylate (GMA) as a reactive compatibilizer. Compatibilization process has been done by melt mixing the PLA/starch and GMA with a twin screw extruder and exposing the PLA/starch/GMA mixture to electron beam at room temperature. The exposure process was carried out to induce definite interfacial adhesion at the interface between PLA and starch through electron beam-initiated graft copolymerization by the medium of the GMA. To testify the effect of this compatibilization strategy, rheological, mechanical, and morphological properties of the composite were analyzed. The scanning electron micrographs of the cryofracture and tensile fracture surfaces of the composites revealed that the interfacial adhesion between PLA and starch was greatly improved by this strategy. Fourier transform infrared study confirmed the grafting reaction between PLA and starch. The reaction schemes were proposed to understand the reaction mechanisms at the interface.     

Effect of Dieckol, a Component of Ecklonia cava, on the Promotion of Hair Growth

This study was conducted to evaluate the effect of Ecklonia cava, a marine alga native to Jeju Island in Korea, on the promotion of hair growth. When vibrissa follicles were cultured in the presence of E. cava enzymatic extract (which contains more than 35% of dieckol) for 21 days, E. cava enzymatic extract increased hair-fiber length. In addition, after topical application of the 0.5% E. cava enzymatic extract onto the back of C57BL/6 mice, anagen progression of the hair-shaft was induced. The treatment with E. cava enzymatic extract resulted in the proliferation of immortalized vibrissa dermal papilla cells (DPC). Especially, dieckol, among the isolated compounds from the E. cava enzymatic extract, showed activity that increased the proliferation of DPC. When NIH3T3 fibroblasts were treated with the E. cava enzymatic extract and the isolated compounds from the E. cava enzymatic extract, the E. cava enzymatic extract increased the proliferation of NIH3T3 fibroblasts, but the isolated compounds such as eckol, dieckol, phloroglucinol and triphlorethol-A did not affect the proliferation of NIH3T3 fibroblasts. On the other hand, the E. cava enzymatic extract and dieckol significantly inhibited 5α-reductase activity. These results suggest that dieckol from E. cava can stimulate hair growth by the proliferation of DPC and/or the inhibition of 5α-reductase activity.     

Correlation of increased antioxidation with the phenolic compound and amino acids contents of Camellia sinensis leaf extracts following ultra high pressure extraction

Antioxidants are indispensable for protecting skin cell membranes against oxidative injury caused by reactive oxygen species and other free radicals. Likewise, phenolic compounds are also important barriers to such oxidative injury. In this study, we examined the correlation between increased antioxidation and the contents of phenolic compounds and amino acids in Camellia sinensis leaf extracts obtained by ultra-high pressure extraction. Compared with extracts obtained by leaching and ultrasonic extraction, to evaluate whether this method can improve the pharmacologic effects of C. sinensis leaves. The ultra-high pressure (50 and 100 MPa) extracts had tremendous enhancement of their extraction yield, 1,1-diphenyl-2-picrylhydrazyl (free radical)-scavenging activity and superoxide anion radical scavenging activity, as well as the total phenolic, amino acid, and caffeine contents. The antioxidative effects were promoted not only by the phenolic compounds contents but also by other factors such as the amino acids content in the C. sinensis leaf extracts. These effects showed pressure-dependent increase with the enhanced phenolic compound and amino acid contents of the ultra high pressure extracts. Taken together, ultra high pressure extraction is a potentially useful method for the pharmaceutical, cosmetic, and food industries, because it improves the antioxidative effects of C. sinensis leaves.     

The characteristics of cutting forces in the micro-milling of AISI D2 steel

The interaction effect of parameters to surface topography and cutting forces is investigated, and the magnitudes of these parameters are determined in the micro-milling of AISI D2 steel. The results show that the feed per tooth has a prominent impact on the surface topography. Due to the low feed per tooth to cutting edge radius ratio, a high surface roughness and a high amount of burrs are obtained in micro-milling. In micro cutting, the cutting forces present are small; in addition, the radial thrust cutting forces are greater than the principal cutting forces. This research proves that the micro-milling process can be applied to the manufacturing of AISI D2 steel micro parts and presents experimental evidence and possible solutions to the cutting parameters.