During the capillary extrusion with several different polyethylenes, we observe an abnormal rheological behavior. The nominal viscosity of polyethylene melt in the gross melt fracture regime does not ...change with a temperature. All polyethylenes tested show same behaviors. More interestingly, the nominal viscosity in the gross melt fracture regime shows even no molecular weight dependency when PEs have similar molecular structures (degree of branching and co-monomer content). From various experiments, we conclude that this abnormal phenomenon is relevant to the structural change with the melt temperature.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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•A novel flexible photodetector composed of 2D-ZnO/1D-GaN was fabricated through two step growth method.•A striking photoresponse was observed for 2D-ZnO/1D-GaN heterojunction under ...UV illumination.•Piezo-phototronic effect is utilized to enhance the performances of photodetector.•The photoresponsitivity of the photodetector enhances by one order under tensile strain.
Here in, we report on the fabrication of a flexible ultraviolet photodetector composed of two dimensional (2D) ZnO nanosheets (NSs) and one dimensional (1D) GaN nanorods (NRs). ZnO NSs were grown on the surface of GaN NRs to form 2D/1D heterojunction via simple hydrothermal method. A striking photoresponse was observed across 2D-ZnO/1D-GaN heterojunction under UV illumination. The photoresponsitivity and detectivity of the photodetector enhanced by two order magnitude than that of 1D GaN NRs. Furthermore, under a tensile strain the photoresponsivity of this photodetector was also tuned through piezo-phototronic effect arising from ZnO NSs. Due to lowering of barrier height under the application of strain, more photogenerated electron-hole pairs can transport through the heterojunction without recombination, resulting in enhanced photorespositivity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•The silymarin content and the presence of individual compounds showed variations over the harvesting period.•Among 6 countries, the seeds from South Korea consistently exhibited the highest ...silymarin content throughout the three years.•An inverse relationship between the content of silydianin and silybin B was observed: a higher silydianin content corresponds to a lower silybin B content.
Silybum marianum, also known as milk thistle, is a medicinal plant belonging to the Asteraceae family. Its seeds contain a high amount of silymarin, which is considered a natural compound that exhibits a wide range of therapeutic properties. This study was conducted to analyze the silymarin content in S. marianum seeds originating from five countries and harvested in three different years using the high-performance liquid chromatography-diode array detector (HPLC/DAD) method. The results revealed that the silymarin content and the presence of individual compounds showed variations over the harvesting period. Seeds from South Korea consistently exhibited the highest silymarin content throughout the three years. In addition, a possible relationship between silydianin and silybin B content was observed: higher silydianin content corresponded to lower silybin B content. There are two chemotypes: a high silybin type (chemotype A) and a high silydianin type (chemotype B). These findings highlight the impact of environmental factors, harvest time, and source material on the silymarin content, providing valuable insights for the selection of suitable materials for silymarin extraction and their potential application in health products.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this paper, we propose a curved projection integral imaging system to improve the horizontal and vertical viewing angles. The proposed system can be easily implemented by additional use of a ...large‐aperture convex lens in conventional projection integral imaging. To obtain the simultaneous display of 3D images through real and virtual image fields, we propose a computer‐generated pickup method based on ray optics and elemental images, which are synthesized for the proposed system. To show the feasibility of the proposed system, preliminary experiments are carried out. Experimental results indicate that our system improves the viewing angle and displays 3D images simultaneously in real and virtual image fields.
High-quality Bi
Se
thin films with topological insulating properties at room temperature have recently attracted much attention as one of the promising materials for realizing innovative electronic ...and optoelectronic devices. Here, we report the high crystallinity growth of Bi
Se
thin films on a patterned sapphire substrate (PSS) by using a vapor-phase transport deposition with minimizing thermal dissociation of Se atoms vaporized in Bi
Se
powder. This PSS not only reduces the large dislocation of heterogeneously grown Bi
Se
on a sapphire substrate but also induces enhanced light absorption in the visible to near-infrared (IR) ranges compared to Bi
Se
on planar sapphire substrates. Thus, the Bi
Se
thin film laterally grown on the PSS reveals uniform surface properties and high crystallinity in the rhombohedral lattice phase with a full width at half maximum of 0.06° for the XRD (003) peak. Also, the photoresponse of the fabricated IR conversion device using Bi
Se
/PSS heterostructure exhibits excellent performance and high reliability with no degradation after continuous switching. As a result, the device constructed with the Bi
Se
/PSS exhibits one order of magnitude higher NIR induced-photocurrent and 1-2 orders of magnitude faster photo-switching than that with Bi
Se
/Al
O
. Such an enhancement in the device performance of Bi
Se
/PSS is confirmed by the increased absorption spectra in visible and NIR ranges and the improved light absorption distribution.
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In this paper, we propose an occlusion removal technique for improved recognition of 3D objects that are partially occluded in computational integral imaging (CII). In the reconstruction process of a ...3D object which is partially occluded by other objects, occlusion degrades the resolution of reconstructed 3D images and thus this affects negatively the recognition of a 3D object in CII. To overcome this problem, we introduce a method to eliminate occluding objects in elemental image array (EIA) and the proposed method is applied to 3D object recognition by use of CII. To our best knowledge, this is the first time to remove occlusion in CII. In our method, we apply the elemental image to sub-image (ES) transform to EIA obtained by a pickup process and those sub-images are employed for occlusion removal. After the transformation, we correlate those sub-images with a reference sub-image to locate occluding objects and then we eliminate the objects. The inverse ES transform provides a modified EIA. Actually, the modified EIA is considered to be an EIA without the object that occludes the object to be reconstructed. This can provide a substantial gain in terms of the image quality of 3D objects and in terms of recognition performance. To verify the usefulness of the proposed technique, some experimental results are carried out and the results are presented.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Dynamic rheological properties of PP-based long glass fiber-reinforced thermoplastics (LFT) were investigated. Weight fractions of the glass fibers investigated in the present study ranged from 0.15 ...to 0.5, which are higher than those of previous studies. We observed very abnormal rheological behavior. Complex viscosity (η*) of the LFT increased with the glass fiber content up to 40 wt. %. However, the η* with a weight fraction of 0.5 is observed to be lower than that of LFT with a weight fraction of 0.4 in spite of higher glass fiber content. From various experiments, we found that this abnormal behavior is analogous to the rheological behavior of a lyotropic liquid crystalline polymer solution and concluded that the abnormal rheological behavior for the LFT is attributed to the formation of a liquid crystal- like structure at high concentrations of long glass fibers.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
High-quality Bi2Se3 thin films with topological insulating properties at room temperature have recently attracted much attention as one of the promising materials for realizing innovative electronic ...and optoelectronic devices. Here, we report the high crystallinity growth of Bi2Se3 thin films on a patterned sapphire substrate (PSS) by using a vapor-phase transport deposition with minimizing thermal dissociation of Se atoms vaporized in Bi2Se3 powder. This PSS not only reduces the large dislocation of heterogeneously grown Bi2Se3 on a sapphire substrate but also induces enhanced light absorption in the visible to near-infrared (IR) ranges compared to Bi2Se3 on planar sapphire substrates. Thus, the Bi2Se3 thin film laterally grown on the PSS reveals uniform surface properties and high crystallinity in the rhombohedral lattice phase with a full width at half maximum of 0.06° for the XRD (003) peak. Also, the photoresponse of the fabricated IR conversion device using Bi2Se3/PSS heterostructure exhibits excellent performance and high reliability with no degradation after continuous switching. As a result, the device constructed with the Bi2Se3/PSS exhibits one order of magnitude higher NIR induced-photocurrent and 1–2 orders of magnitude faster photo-switching than that with Bi2Se3/Al2O3. Such an enhancement in the device performance of Bi2Se3/PSS is confirmed by the increased absorption spectra in visible and NIR ranges and the improved light absorption distribution.
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We investigated the coherent acoustic and optical phonon dynamics in a Ge
2
Sb
2
Te
5
phase change material by using pump-probe spectroscopy. Oscillating reflectivity changes with oscillation period ...and de-phasing time on a timescale of tens of picoseconds were observed and could be consistently explained by coherent acoustic phonon generation in the form of a strain pulse propagating into substrate. The temperature-dependent frequency shift of the coherent optical
A
1
phonon mode was due to a three-phonon anharmonic decay while its de-phasing was dominated by temperatureindependent phonon-vacancy scattering at low temperature. A laser-fluence-dependent
A
1
phonon mode softening and a dephasing rate increase were observed and attributed to the high density of electrons and the accompanying lattice distortion, as well as the increase in the lattice temperature.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
