100 research outputs found

    COMPARISON OF VOLATILE COMPOSITION OF SUPERCRITICAL CARBON DIOXIDE EXTRACT FROM RHIZOMES OF KOREAN MEDICINAL PLANT 'CHUN-KUNG' (CNIDIUM OFFICINALE MAKINO) BY DIRECT-AND SPME-GC/MS

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    Objective: The main purpose of this study was to evaluate the volatile composition of supercritical fluid extract (SFE) obtained from Cnidium officinale Makino rhizomes. Methods: GC/MS analyses were carried out with the direct- and solid phase microextraction (SPME) of SFE obtained from rhizomes. In addition, GC/MS analysis was performed for the rhizomes of C. officinale using SPME. Results: SPME-GC/MS analysis of the rhizomes revealed the separation of 23 components. Among these, β-phellandrene (20.38%), dictyotene (12.98%), β-pinene (10.59%), β-selinene (9.45%), eugenol (7.71%) and β-farnesene (7.09%) were found to be major components. In the SFE analyzed by direct-GC/MS, linoleic acid (19.26%), 2-methoxy-4-vinylphenol (18.98%), hexadecanoic acid (12.15%), and β-selinene (9.44%) were identified as major components. Whereas, 3,4-dihydrocoumarin (16.94%), shyobunone (14.07%), dictyotene (10.65%), p-cresol (10.17%), zierone (6.36%) and umbellulone (5.71%) were major components in the SFE analyzed by SPME-GC/MS. Conclusion: The present study clearly suggested that the SPME-GC/MS analysis of SFE provided the separation of more number with diverse groups of compounds than the direct-GC/MS

    The Protective Effect of Apamin on LPS/Fat-Induced Atherosclerotic Mice

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    Apamin, a peptide component of bee venom (BV), has anti-inflammatory properties. However, the molecular mechanisms by which apamin prevents atherosclerosis are not fully understood. We examined the effect of apamin on atherosclerotic mice. Atherosclerotic mice received intraperitoneal (ip) injections of lipopolysaccharide (LPS, 2 mg/kg) to induce atherosclerotic change and were fed an atherogenic diet for 12 weeks. Apamin (0.05 mg/kg) was administered by ip injection. LPS-induced THP-1-derived macrophage inflammation treated with apamin reduced expression of tumor necrosis factor (TNF)-α, vascular cell adhesion molecule (VCAM)-1, and intracellular cell adhesion molecule (ICAM)-1, as well as the nuclear factor kappa B (NF-κB) signaling pathway. Apamin decreased the formation of atherosclerotic lesions as assessed by hematoxylin and elastic staining. Treatment with apamin reduced lipids, Ca2+ levels, and TNF-α in the serum from atherosclerotic mice. Further, apamin significantly attenuated expression of VCAM-1, ICAM-1, TGF-β1, and fibronectin in the descending aorta from atherosclerotic mice. These results indicate that apamin plays an important role in monocyte/macrophage inflammatory processing and may be of potential value for preventing atherosclerosis

    The Protective Effects of Melittin on Propionibacterium acnes–Induced Inflammatory Responses In Vitro and In Vivo

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    Melittin is the main component in the venom of the honey bee (Apis mellifera). It has multiple effects including antibacterial, antiviral, and anti-inflammatory activities in various cell types. However, the anti-inflammatory mechanisms of melittin have not been elucidated in Propionibactierium acnes (P. acnes)–induced keratinocyte or inflammatory skin disease animal models. In this study, we examined the effects of melittin on the production of inflammatory cytokines in heat-killed P. acnes–induced HaCaT cells. Heat-killed P. acnes–treated keratinocytes increased the expression of pro-inflammatory cytokines and Toll-like receptor 2. However, melittin treatment significantly suppressed the expression of these cytokines through regulation of the NF-κB and MAPK signaling pathways. Subsequently, the living P. acnes (1 × 107 CFU) were intradermally injected into the ear of mice. Living P. acnes–injected ears showed cutaneous erythema, swelling, and granulomatous response at 24 hours after injection. However, melittin-treated ears showed markedly reduced swelling and granulomatous responses compared with ears injected with only living P. acnes. These results demonstrate the feasibility of applying melittin for the prevention of inflammatory skin diseases induced by P. acnes

    High performance polymer light-emitting diodes with N-type metal oxide/conjugated polyelectrolyte hybrid charge transport layers

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    We present an interfacial engineering strategy employing n-type-metal-oxide/conjugated-polyelectrolyte (CPE) hybrid charge-transport layers for highly efficient polymer light-emitting diodes (PLEDs). The hybrid metal-oxide/CPE layer facilitates electron-injection, while blocking hole-transport, and thereby maximizes electron-hole recombination within the emitting layer. A series of metal-oxide/CPE combinations were tested in inverted PLEDs (FTO/metal-oxide/CPF8BT/MoO3/Au). Specifically, HfO2/CPE double layer achieved an electroluminescence (EL) efficiency of up to 25.8 cd/A (@ 6.4 V, one of the highest values reported for fluorescent PLEDs).open11

    Highly efficient plasmonic organic optoelectronic devices based on a conducting polymer electrode incorporated with silver nanoparticles

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    Highly efficient ITO-free polymeric electronic devices were successfully demonstrated by replacement of the ITO electrode with a solution-processed PEDOT:PSS electrode containing Ag nanoparticles (NPs). Polymer solar cells (PSCs) and light emitting diodes (PLEDs) were fabricated based on poly(5,6-bis(octyloxy)-4-(thiophen-2-yl)benzo[c][1,2,5]thiadiazole) (PTBT):PC61BM and Super Yellow as a photoactive layer, respectively. The surface plasmon resonance (SPR) effect and improved electrical conductivity by the Ag NPs clearly contributed to increments in light absorption/emission in the active layer as well as the conductivity of the PEDOT:PSS electrode in PSCs and PLEDs. The ITO-free bulk heterojunction PSCs showed a 1% absolute enhancement in the power conversion efficiency (3.27 to 4.31%), and the power efficiency of the PLEDs was improved by 124% (3.75 to 8.4 lm W-1) compared to the reference devices without Ag NPs. The solution-processable conducting polymer, PEDOT:PSS with Ag NPs, can be a promising electrode for large area and flexible optoelectronic devices with a low-cost fabrication process.close11

    Synergistic surface modification for high-efficiency perovskite nanocrystal light-emitting diodes: divalent metal ion doping and halide-based ligand passivation

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    Surface defects of metal halide perovskite nanocrystals (PNCs) substantially compromise the optoelectronic performances of the materials and devices via undesired charge recombination. However, those defects, mainly the vacancies, are structurally entangled with each other in the PNC lattice, necessitating a delicately designed strategy for effective passivation. Here, a synergistic metal ion doping and surface ligand exchange strategy is proposed to passivate the surface defects of CsPbBr3 PNCs with various divalent metal (e.g., Cd2+, Zn2+, and Hg2+) acetate salts and didodecyldimethylammonium (DDA+) via one-step post-treatment. The addition of metal acetate salts to PNCs is demonstrated to suppress the defect formation energy effectively via the ab initio calculations. The developed PNCs not only have near-unity photoluminescence quantum yield and excellent stability but also show luminance of 1175 cd m−2, current efficiency of 65.48 cd A−1, external quantum efficiency of 20.79%, wavelength of 514 nm in optimized PNC light-emitting diodes with Cd2+ passivator and DDA ligand. The “organic–inorganic” hybrid engineering approach is completely general and can be straightforwardly applied to any combination of quaternary ammonium ligands and source of metal, which will be useful in PNC-based optoelectronic devices such as solar cells, photodetectors, and transistors

    Bimodal Mesoporous Titanium Nitride/Carbon Microfibers as Efficient and Stable Electrocatalysts for Li–O_2 Batteries

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    The rechargeable Li–O_2 battery has been considered as a sustainable chemical power source for electric vehicles and grid energy storage systems due to the high theoretical specific energy (∼3500 Wh/kg). The practical performance of Li–O_2 batteries is, however, still far below expectations. This is mainly attributed to the (1) intrinsic sluggish reaction kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), (2) passivation of the electrodes by electrical isolation and pore blocking, and (3) chemical instability of the organic cell components, i.e., electrolyte, polymer binder, and carbon electrode, in the presence of O_2•– and Li_2O_2. It is crucial to develop highly porous, three-dimensional, conducting cathode catalyst/gas diffusion layer (GDL) architectures possessing superior catalytic activity and stability with respect to the ORR and the OER in order to address these issues. All of these requirements prompted us to examine the catalytic performance of porous framework metal nitride electrodes for Li–O_2 batteries

    Melatonin Membrane Receptors in Peripheral Tissues: Distribution and Functions

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    Many of melatonin’s actions are mediated through interaction with the G-protein coupled membrane bound melatonin receptors type 1 and type 2 (MT1 and MT2, respectively) or, indirectly with nuclear orphan receptors from the RORα/RZR family. Melatonin also binds to the quinone reductase II enzyme, previously defined the MT3 receptor. Melatonin receptors are widely distributed in the body; herein we summarize their expression and actions in non-neural tissues. Several controversies still exist regarding, for example, whether melatonin binds the RORα/RZR family. Studies of the peripheral distribution of melatonin receptors are important since they are attractive targets for immunomodulation, regulation of endocrine, reproductive and cardiovascular functions, modulation of skin pigmentation, hair growth, cancerogenesis, and aging. Melatonin receptor agonists and antagonists have an exciting future since they could define multiple mechanisms by which melatonin modulates the complexity of such a wide variety of physiological and pathological processes

    New Era of Air Quality Monitoring from Space: Geostationary Environment Monitoring Spectrometer (GEMS)

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    GEMS will monitor air quality over Asia at unprecedented spatial and temporal resolution from GEO for the first time, providing column measurements of aerosol, ozone and their precursors (nitrogen dioxide, sulfur dioxide and formaldehyde). Geostationary Environment Monitoring Spectrometer (GEMS) is scheduled for launch in late 2019 - early 2020 to monitor Air Quality (AQ) at an unprecedented spatial and temporal resolution from a Geostationary Earth Orbit (GEO) for the first time. With the development of UV-visible spectrometers at sub-nm spectral resolution and sophisticated retrieval algorithms, estimates of the column amounts of atmospheric pollutants (O3, NO2, SO2, HCHO, CHOCHO and aerosols) can be obtained. To date, all the UV-visible satellite missions monitoring air quality have been in Low Earth orbit (LEO), allowing one to two observations per day. With UV-visible instruments on GEO platforms, the diurnal variations of these pollutants can now be determined. Details of the GEMS mission are presented, including instrumentation, scientific algorithms, predicted performance, and applications for air quality forecasts through data assimilation. GEMS will be onboard the GEO-KOMPSAT-2 satellite series, which also hosts the Advanced Meteorological Imager (AMI) and Geostationary Ocean Color Imager (GOCI)-2. These three instruments will provide synergistic science products to better understand air quality, meteorology, the long-range transport of air pollutants, emission source distributions, and chemical processes. Faster sampling rates at higher spatial resolution will increase the probability of finding cloud-free pixels, leading to more observations of aerosols and trace gases than is possible from LEO. GEMS will be joined by NASA's TEMPO and ESA's Sentinel-4 to form a GEO AQ satellite constellation in early 2020s, coordinated by the Committee on Earth Observation Satellites (CEOS)

    Preparation and Application of Electrodes in Capacitive Deionization (CDI): a State-of-Art Review

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    As a promising desalination technology, capacitive deionization (CDI) have shown practicality and cost-effectiveness in brackish water treatment. Developing more efficient electrode materials is the key to improving salt removal performance. This work reviewed current progress on electrode fabrication in application of CDI. Fundamental principal (e.g. EDL theory and adsorption isotherms) and process factors (e.g. pore distribution, potential, salt type and concentration) of CDI performance were presented first. It was then followed by in-depth discussion and comparison on properties and fabrication technique of different electrodes, including carbon aerogel, activated carbon, carbon nanotubes, graphene and ordered mesoporous carbon. Finally, polyaniline as conductive polymer and its potential application as CDI electrode-enhancing materials were also discussed
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