Cyclopolymerization of 1,1-dipropargyl-1-silacyclobutane and 1,1-dipropargyl-1-silacyclopentane was examined by various transition metal catalysts. WCl
6 was found to be very effective for this ...cyclopolymerization to give high yields of polymers. The polymer structures were characterized to have the conjugated polymer backbone with silacycloalkane moieties. The resulting poly(1,1-dipropargyl-1-silacyclobutane) was insoluble in any organic solvents, whereas the poly(1,1-dipropargyl-1-silacyclopentane) was partially soluble. The conjugated spirocyclic polymers were mostly yellow or light-brown powders, depending on the catalyst systems used. The thermal and oxidative stabilities of the polymer were also studied and discussed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
This study assessed in vitro antioxidant activity (ABTS+ and DPPH) of Vitex rotundifolia seeds collected from two different regions in Korea (Jungjang City and Sindu City). Three extraction methods ...using ethanol, methanol, and water were prepared separately and subjected to quantification by reverse-phase high-performance liquid chromatography-photodiode array (HPLC-PDA) analysis as well as antioxidant testing. Among them, the water-based extract exhibited superior activity in the ABTS+ compared with the ethanol- and methanol-based extracts, while the DPPH assay analysis, revealed that the methanol-based extract had very low antioxidant activity. The concentrations of vanillic acid (1), luteolin (2), vitexicarpin (3), and artemetin (4) were quantified using HPLC-PDA analysis. Vanillic acid (1) was identified as the main antioxidant in V. rotundifolia seeds. Combining the antioxidant activity and quantitative analysis results, the water-based extract was considered to have the highest antioxidant activity. Furthermore, vanillic acid (1) was detected in the leaves and stems of V. rotundifolia plants from different regions, indicating that this species has the potential for use in future antioxidant-applications.
Tin monosulfide (SnS) nanostructures have attracted huge attention recently because of their high absorption coefficient, high photoconversion efficiencies, low energy cost, ease of deposition, and ...so on. Here, in this paper, we report on the low-cost hydrothermal synthesis of the self-assembled SnS nanoflake-like structures in terms of performance for the photodetectors. High-performance photodetectors were fabricated using SnS nanoflakes as active layers and graphene as the lateral electrodes. The SnS photodetectors exhibited excellent photoresponse properties with a high responsivity of 1.7 × 104 A/W and have fast response and recovery times. In addition, the photodetectors exhibited long-term stability and strong dependence of photocurrent on light intensity. These excellent characteristics were attributed to the larger surface-to-volume ratio of the self-assembled SnS nanoflakes and the effective separation of the photogenerated carriers at graphene/SnS interfaces. Additionally, a flexible photodetector based on SnS nanoflakes was also fabricated on a flexible substrate that demonstrated similar photosensitive properties. Furthermore, this study also demonstrates the potential of hydrothermal-processed SnS nanoflakes for high-performance photodetectors and their application in flexible low-cost optoelectronic devices.
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IJS, KILJ, NUK, PNG, UL, UM
4H-SnS2 layered crystals synthesized by a hydrothermal method were used to obtain via liquid phase exfoliation quantum dots (QDs), consisting of a single layer (SLQDs) or multiple layers (MLQDs). ...Systematic downshift of the peaks in the Raman spectra of crystals with a decrease in size was observed. The bandgap of layered QDs, estimated by UV-visible absorption spectroscopy and the tunneling current measurements using graphene probes, increases from 2.25 eV to 3.50 eV with decreasing size. 2-4 nm SLQDs, which are transparent in the visible region, show selective absorption and photosensitivity at wavelengths in the ultraviolet region of the spectrum while larger MLQDs (5-90 nm) exhibit a broad band absorption in the visible spectral region and the photoresponse under white light. The results show that the layered quantum dots obtained by liquid phase exfoliation exhibit well-controlled and regulated bandgap absorption in a wide tunable wavelength range. These novel layered quantum dots prepared using an inexpensive method of exfoliation and deposition from solution onto various substrates at room temperature can be used to create highly efficient visible-blind ultraviolet photodetectors and multiple bandgap solar cells.
In this letter, we propose a novel computational integral imaging reconstruction technique based on a lenslet array model. The proposed technique provides improvement of viewing images by extracting ...multiple pixels from elemental images according to ray tracing based on the lenslet array model. To show the feasibility of the proposed technique, we analyze it according to ray optics and present the experimental results.
Total polyphenol and total flavonoid assays were performed to characterize the relationships between the color of Peucedanum japonicum (PJ) seed coat and stem and the content of phytochemical ...compounds. The samples were divided into two groups based on their stem and seed coat color, with each group containing 23 samples. The stem color group was subdivided into green, light red, and red, whereas the seed coat color group was divided into light brown, brown, and dark brown. In the stem color group, the light red stems exhibited the highest content of phytochemical compounds, with levels over 10% higher than those of the stems of the other colors. Moreover, among the top ten samples with the highest total polyphenol content, eight samples were light red, and the light red group also exhibited the highest total flavonoid content among the examined color groups. In terms of the seed coat color, the plants grown from dark brown seeds exhibited the highest contents of both total polyphenols and total flavonoids. In conclusion, PJ plants with dark brown seeds and light red stems contained the highest levels of phytochemical compounds. Collectively, our findings provide a valuable basis for future seed selection of PJ for pharmaceutical purposes.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Medicinal plants, rich sources of bioactive compounds such as Platycodon grandiflorus, Codonopsis lanceolata, Paeonia japonica, and Lonicera japonica, have been an integral part of traditional ...medicine for centuries. Therefore, this study aims to explore the botanical and chemical profiles of key Korean medicinal plants: steamed Platycodonis Radix, steamed Codonopsidis Radix, non-steamed Paeoniae Radix (NPR), and non-steamed Lonicerae Flos (NLF), investigating their constituents and antioxidant potential. Assessments of total polyphenol content (TPC) and total flavonoid content (TFC) revealed considerable variation among the samples, with higher TPC generally correlating with increased TFC. Among the samples, NLF exhibited the highest TPC and TFC, indicative of its rich polyphenol and flavonoid content. Antioxidant assays using 2,2- diphenyl-1-picrylhydrazyl and 2,2′-azinobis(3-ethylbenzothiazoline- 6-sulfonic acid) methods identified NPR and NLF as promising natural antioxidants, though less potent than ascorbic acid. Highperformance liquid chromatography analysis revealed key compounds in each sample, with paeoniflorin particularly abundant in NLF, probably contributing to its antioxidant activity.
These findings offer fundamental insights into developing functional foods and Chinese medicinal herb mixtures and serve as a valuable reference for future research on traditional herbal medicine analysis and product formulation. KCI Citation Count: 0
In this paper, we propose a novel performance-enhanced computational integral imaging reconstruction (CIIR) scheme by additional use of an imaging lens. In the proposed scheme, elemental images can ...be obtained by using a simultaneous pickup scheme of far three-dimensional (3D) objects from the lenslet array in both real and virtual image fields. And additional imaging lens produces an image shift effect of 3D objects located far away from the lenslet array and improve the visual quality of reconstructed images in CIIR by overcoming limitation of pickup range in integral imaging. To show the usefulness of the proposed system, some experiments are carried out for real 3D objects and its results are presented.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
In this paper, we propose a computational integral imaging reconstruction (CIIR) method using a round mapping model to improve the viewing quality of 3‐D images. The proposed CIIR method can overcome ...the problem of non‐uniformly reconstructed images caused by the conventional method. To show the usefulness of proposed method, some experiments are carried out and the results are presented.
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