Ruthenium dye-sensitized SnO2/TiO2 coupled solar cells

The photoelectrochemical behaviors of RuL₂(NCS)₂ dye-sensitized SnO₂/TiO₂ coupled solar cell was studied and compared with TiO₂ single system. The coupled system shows higher incident photon-to-current conversion efficiency (IPCE) value than the single system. A maximum IPCE value in the coupled system with 3.5 μm-thick SnO₂ and 7 μm-thick TiO₂ attained 82.4% at 530 nm wavelength. The higher IPCE value in the coupled system is attributed to the charge separation by fast electron transfer process from the excited RuL₂(NCS)₂ dye to TiO₂ to SnO₂ in the system with different energy level.     

Effects of various post-treatments on carbon nanotube films for reliable field emission

In this report, the FE characteristics of carbon nanotubes (CNTs) treated using both thermal annealing and mechanical coatings on the as-grown CNTs systematically studied. It was found that in the high temperature annealed samples, CNTs were attacked at its root during annealing due to a small amount of oxygen, and were pulled out of the substrate in places after FE measurements because of the contact resistance. However, for the mechanically coated samples both with spin on glass (SOG) and polymethyl methacrylate (PMMA), CNTs were found to be nearly intact after FE measurements and showed reliable FE characteristics over repeatable voltage scan. The reliability of CNTs during FE could be owing to the strong adhesion of CNTs to the substrate both by SOG and PMMA coatings.     

Highly sensitive and selective dopamine detection by an amperometric biosensor based on tyrosinase/MWNT/GCE

Dopamine (3,4-dihydroxylphenyl ethylamine) is the most significant neurotransmitter in the human nervous system. Abnormal dopamine levels cause fatal neurological disorders, and thus measuring dopamine level in actual samples is important. Although electrochemical methods have been developed for detecting dopamine with high accuracy, certain substances (e.g., ascorbic acid) in actual samples often interfere with electrochemical dopamine detection. We developed tyrosinase-based dopamine biosensor with high sensitivity and selectivity. An electrochemically pretreated tyrosinase/multi-walled carbon nanotube-modified glassy carbon electrode (tyrosinase/MWNT/GCE) was prepared as an amperometric biosensor for selective dopamine detection. For optimizing the biosensor performance, pH, temperature, and scan rate were investigated. The electrochemically pretreated tyrosinase/MWNT/GCE exhibited not only the highest sensitivity (1,323 mAM^?1 cm^?2) compared to previously reported tyrosinase-based dopamine sensors, but also good long-term stability, retaining 90% of initial activity after 30 days. Additionally, ascorbic acid, a major interfering substances, was not oxidized at the potential used to detect dopamine oxidation, and the interfering effect of 4mM ascorbic acid was negligible when monitoring 1mM dopamine. Consequently, the electrochemically pretreated tyrosinase/MWNT/GCE is applicable for highly selective and sensitive dopamine detection in actual samples including interfering substances, thereby extending the practical use to monitor and diagnose neurological disorders.     

NO removal by CH4 on Co-NaX-CO and Ag-NaX catalysts in a dual-bed system

NO removal using CH₄ as a reductant in a dual-bed system has been investigated with Co-NaX and Ag-NaX catalysts, which were prepared by Co²⁺-, Ag⁺-ion exchange into zeolite NaX, respectively, and activation for 5 h at 500 °C. The experimental result has been compared with that of a Co-NaX-CO catalyst, additionally pre-treated under CO flow for the Co-NaX catalyst. The cobalt crystal structure of a Co-NaX-CO catalyst is Co₃O₄, which promotes NO oxidation to NO₂ by excess O₂ at a low temperature (523 K). The mechanical mixture of Co-NaX-CO and Ag-NaX catalysts shows a synergy effect on NO reduction to N₂ by CH₄ in the presence of excess O₂ and H₂O, but the NO reduction decreases quickly as time passes. However, the NO reduction to N₂ in a deNO bed at 523 K and a deNO₂ bed at 423 K, which are relatively lower than the reaction temperatures for common SCR systems, still remained at 67% even in a H₂O 10% gas mixture after 160 min.     

Prediction of a CDMA output spectrum based on intermodulationproducts of two-tone test

A prediction method of a code-division multiple-access (CDMA) output spectrum based on intermodulation (IM) products of a two-tone test is proposed in this paper. An RF power amplifier is mathematically modeled by a complex envelope transfer function and, using this model, analytical expressions of IM products and a CDMA output spectrum are derived, respectively. By combining these two expressions, we finally derive an analytical expression that relates IM products to a CDMA output spectrum. It is shown in this expression that not only AM-AM, but also AM-PM distortion affects the CDMA output spectrum. Comparison between the measured and predicted results shows that the output spectrum predicted by this method agrees well with the measured spectrum     

Comparison of consumer perception and liking of <Emphasis Type="Italic">bulgogi</Emphasis> marinade sauces between Korea and Japan using flash profiling

This study compared the perception of and preference for seven bulgogi marinade sauces between Korean and Japanese consumers. Flash profiling (10 panelists each) and consumer test (97 Japanese and 102 Koreans) were conducted. Results showed that both Korean and Japanese panelists perceived the samples similarly but described using different terms. There were significant crosscultural differences in most liking and just-about-right attributes, except texture liking and sweetness. Both consumer panelists preferred sweeter samples, but Japanese consumers rated liking for less sweet samples higher than Korean consumers. Japanese consumers considered strong saltiness, umami, and soy sauce flavor as “just-about-right,” whereas Korean consumers considered the same levels as “much too strong”. Familiarity showed a significantly positive correlation with both Korean and Japanese consumers’ liking, but authenticity was only significantly correlated with Korean consumers’ liking. This indicates that perception of authenticity might not have a strong impact on Japanese consumers’ liking.     

Antioxidant and <Emphasis Type="Italic">α</Emphasis>-glucosidase inhibitory activities of different solvent extracts of skullcap (<Emphasis Type="Italic">Scutellaria baicalensis</Emphasis>)

In this study, different solvent extracts of skullcap (Scutellaria baicalensis) were assayed for their total phenol content (TPC), antioxidant activity [determined as DPPH radical scavenging activity, superoxide dismutase (SOD)-like activity, oxygen radical absorbance capacity (ORAC) assay, and comet assay], and α-glucosidaseinhibitory activity. The TPC of skullcap ranged from 9.06 mg/g gallic acid equivalents (GAE) for acetone extract (AE) to 91.8 mg/g GAE for methanol extract (ME). AE, which had a low TPC, exhibited the highest DPPH radical scavenging activity and SOD-like activity. TPC positively correlated with the ORAC assay (r=0.96, p<0.001). All skullcap extracts significantly reduced the hydrogen peroxide-induced DNA damage in human leukocytes. ME with a high TPC and ORAC value showed the highest α-glucosidase inhibition. The difference in the biological activities of the extracts may be due to the differences in their chemical structure or polarity. Therefore, the results obtained indicate that might be a potential source of compounds with health-protective effects. ME, in particular, might be a prospective therapeutic agent for diabetes.     

Transparent and flexible oxide thin-film-transistors using an aluminum oxide gate insulator grown at low temperature by atomic layer deposition

Al₂O₃ dielectric layers with a dense and atomically flat surface were grown at relatively low temperatures of 150 °C by atomic layer deposition (ALD) for use as the gate oxide of transparent and flexible oxide thin-film-transistors (TFTs). The ALD growth of the high quality Al₂O₃ with a less rough surface at 120 °C allowed us to use the liftoff process without wet chemical etching and made the fabrication method for flexible electronics simple. This also improved the electrical performance of the oxide TFTs, such as high field effect mobility, low subthreshold gate swing, and low hysteresis behavior, due to the low charge trap sites at the gate oxide and channel interface. Finally, we fabricated InGaZnO TFTs with good device performance on a flexible substrate with poly-4-vinylphenol coating at a maximum processing temperature of 120 °C.