http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Enhanced production of nargenicin A(1) and generation of novel glycosylated derivatives.
Dhakal, Dipesh,Le, Tuoi Thi,Pandey, Ramesh Prasad,Jha, Amit Kumar,Gurung, RitBahadur,Parajuli, Prakash,Pokhrel, Anaya Raj,Yoo, Jin Cheol,Sohng, Jae Kyung Humana Press 2015 Applied biochemistry and biotechnology Vol.175 No.6
<P>Nargenicin A(1), an antibacterial polyketide macrolide produced by Nocardia sp. CS682, was enhanced by increasing the pool of precursors using different sources. Furthermore, by using engineered strain Nocardia sp. ACC18 and supplementation of glucose and glycerol, enhancement was similar to 7.1 fold in comparison to Nocardia sp. CS682 without supplementation of any precursors. The overproduced compound was validated by mass spectrometry and nuclear magnetic resonance analyses. The novel glycosylated derivatives of purified nargenicin A(1) were generated by efficient one-pot reaction systems in which the syntheses of uridine diphosphate (UDP)-alpha-D-glucose and UDP-alpha-D-2-deoxyglucose were modified and combined with glycosyltransferase (GT) from Bacillus licheniformis. Nargenicin A(1) 11-O-beta- D-glucopyranoside, nargenicin A(1) 18-O-beta-D-glucopyranoside, nargenicin A(1)11 18-O-beta-D- diglucopyranoside, and nargenicin 11-O-beta-D-2-deoxyglucopyranoside were generated. Nargenicin A(1) 11-O-beta-D-glucopyranoside was structurally elucidated by ultra-high performance liquid chromatography-photodiode array (UPLC-PDA) conjugated with high-resolution quantitative time-of-flight-electrospray ionization mass spectroscopy (HR-QTOF ESI-MS/MS), supported by one- and two-dimensional nuclear magnetic resonance studies, whereas other nargenicin A(1) glycosides were characterized by UPLC-PDA and HR-QTOF ESI-MS/MS analyses. The overall conversion studies indicated that the one-pot synthesis system is a highly efficient strategy for production of glycosylated derivatives of compounds like macrolides as well. Furthermore, assessment of solubility indicated that there was enhanced solubility in the case of glycoside, although a substantial increase in activity was not observed.</P>
Dhakal, Rajendra,Jung, Younsu,Park, Hyejin,Cho, Gyoujin,Kim, Nam Young Hindawi Limited 2015 Journal of nanomaterials Vol.2015 No.-
<P>We present a low-power, cost-effective, highly reproducible, and disposable bandstop filter by employing high-throughput screen-printing technology. We apply large-scale printing strategies using silver-nanoparticle-based ink for the metallization of conductive wires to fabricate a bandstop filter on a polyethylene terephthalate (PET) substrate. The filter exhibits an attenuation pole at 4.35 GHz with excellent in-and-out band characteristics. These characteristics reflect a rejection depth that is better than −25 dB with a return loss of −0.75 dB at the normal orientation of the PET substrate. In addition, the filter characteristics are observed at various bending angles (0°, 10°, and 20°) of the PET substrate with an excellent relative standard deviation of less than 0.5%. These results confirm the accuracy, reproducibility, and independence of the resonance frequency. This screen-printing technology for well-defined nanostructures is more favorable than other complex photolithographic processes because it overcomes signal losses due to uneven surface distributions and thereby reveals a homogeneous distribution. Moreover, the proposed methodology enables incremental steps in the process of producing highly flexible and cost-effective printed-electronic radio devices.</P>
Effects of spark dielectric barrier discharge plasma on water sterilization and seed germination
Dhakal Oat Bahadur,Dahal Roshani,Acharya Tirtha Raj,Lamichhane Prajwal,Gautam Sandhya,Lama Bhupendra,khanal Raju,Kaushik Nagendra Kumar,최은하,Chalise Roshan 한국물리학회 2023 Current Applied Physics Vol.54 No.-
This study investigated the effects of spark dielectric barrier discharge (SDBD) plasma on water sterilization and seed germination using an in-situ treatment method. The plasma diagnostics used I–V characteristics and optical emission spectroscopy. The electron, rotational, and vibrational temperature, as well as electron density were measured. The findings revealed that SDBD plasma treatment caused significant changes in the physicochemical properties of the liquids. In addition, the concentrations of H2O2, NO2− and NO3− were increased after 8 min of plasma treatment to 30, 40, and 100 mgL−1, respectively. The effectiveness of the SDBD plasma treatment was evaluated based on bacterial inactivation and seed germination. After 8 min of plasma treatment, an almost complete removal of E. coli and S. aureus was achieved. Furthermore, the germination of coriander seeds was enhanced when they were treated with SDBD plasma for 5 min. SDBD plasma shows promise for water sterilization, seed germination, and sustainability.
Dhakal, Krishna P.,Roy, Shrawan,Yun, Seok Joon,Ghimire, Ganesh,Seo, Changwon,Kim, Jeongyong The Royal Society of Chemistry 2017 Journal of materials chemistry. C, Materials for o Vol.5 No.27
<▼1><P>Spatially heterogeneous effects of bis(trifluoromethane)sulfonimide (TFSI) and benzyl viologen (BV) treatment on the optical properties of triangular monolayer tungsten disulfides are investigated by nanoscale spectral imaging.</P></▼1><▼2><P>Chemical treatments were recently shown to be very effective in enhancing the exciton emission of monolayer transition metal dichalcogenides (1L-TMDs) by suppressing the exciton quenching caused by structural defects. However, the effects of these chemical treatments varied greatly depending on the synthesis method and the type of 1L-TMD; therefore, the exact origin of the emission enhancement is still elusive. Here we report the spatially heterogeneous effects of bis(trifluoromethane)sulfonimide (TFSI) and benzyl viologen (BV) treatment on the optical properties of triangular 1L-WS2 grown by chemical vapor deposition (CVD). Nanoscale photoluminescence (PL) and Raman spectral maps showed that TFSI had a minimal effect on the inner region of the triangular WS2 grain, whereas the PL of the edge region was enhanced up to 25 times; further, BV reduced the PL, also more strikingly in the edge region. Systematic variation of the spectral weights among neutral excitons, trions, and bi-excitons indicated that p-doping and n-doping with TFSI and BV, respectively, occurred in both the inner and edge regions; however, the PL enhancement was attributed mainly to the reduction of structural defects caused by TFSI treatment. Our observation of the spatially heterogeneous effects of chemical treatment suggests that the inner and edge regions of CVD-grown 1L-WS2 are populated with different types of structural defects and helps in clarifying the mechanism by which chemical treatment enhances the optical properties of 1L-TMDs.</P></▼2>
Dhakal, K.,Lee, H.,Lee, J.,Lee, S.,Joo, J.,Kim, J. Royal Society of Chemistry 2014 Journal of Materials Chemistry C Vol.2 No.10
We prepared gold nanoparticle (Au NP) hybridized organic rubrene nanofibers (NFs) using a convenient electrospinning method. Au NPs of size 2-3 nm were incorporated throughout the light emitting rubrene NFs, which was confirmed by high resolution transmission electron microscopy. Au NP hybridized rubrene NFs showed a distinct nanoporous surface, compared to the smooth surface of rubrene NFs. Nanoscale confocal spectroscopy was performed on a single NF level and the results showed that the photoluminescence (PL) of the hybrid NFs made with 15 wt% Au NP mixture solution was 2.5 times higher than the PL of the rubrene NFs. And the optical extinction (scattering and absorption) of hybrid NFs increased monotonically with increasing Au NP concentrations. These enhanced optical properties of hybrid NFs were attributed to localized surface plasmon resonance of the embedded Au NPs. Structural modification from the monoclinic phase to the orthorhombic phase of the rubrene structure was obtained by XRD analysis indicating a better ordering along the rubrene ab plane of the hybrid NFs.
Selection for soyabeans with high and environmentally stable lutein concentrations
Dhakal, Krishna Hari,Choung, Myoung-Gun,Hwang, Young-Sun,Fritschi, Felix B.,Shannon, J. Grover,Lee, Jeong-Dong Cambridge University Press 2014 Plant genetic resources Vol.12 No.1
<P>Lutein has significant nutritional benefits for human health. Therefore, enhancing soybean lutein concentrations is an important breeding objective. However, selection for soybeans with high and environmentally stable lutein concentrations has been limited. The objectives of this study were to select soybeans with high seed lutein concentrations and to determine the stability of lutein concentrations across environments. A total of 314 genotypes were screened and 18 genotypes with high lutein concentrations and five genotypes with low lutein concentrations were selected for further examination. These 23 genotypes and two check varieties were evaluated under six environments (two planting dates for 2 years at one location and two planting dates for 1 year at another location). Lutein concentrations were influenced by genotype, environment and genotype × environment interactions. Genotypes with late maturity and low lutein concentrations were more stable than those with early maturity and high concentrations. Early (May) planting resulted in greater lutein concentrations than late (June) planting. Among the genotypes evaluated, PI603423B (7.7 μg/g) and PI89772 (5.8 μg/g) had the greatest mean lutein concentrations and exhibited medium and high stability across the six environments, respectively. Thus, these genotypes may be useful for breeding soybeans with high and stable seed lutein concentrations.</P>
Fatty Acid Composition in each Structural Part of Soybean Seed and Sprout
Dhakal, Krishna Hari,Jeong, Yeon-Shin,Lee, Jeong-Dong,Baek, In-Youl,Ha, Tae-Joung,Hwang, Young-Hyun 한국작물학회 2009 Journal of crop science and biotechnology Vol.12 No.2
Fatty acid composition and $C_{18:2}:C_{18:3}$ of soybean seed and sprout is important for soy-industries to manufacture quality products. Six soybean varieties were analyzed by gas chromatography to determine fatty acid composition and linoleic to linolenic acid ratio ($C_{18:2}:C_{18:3}$) in seed, sprout, and their structural parts. In the case of whole seed and its structural parts, significant variation in fatty acid composition and $C_{18:2}:C_{18:3}$ were observed between varieties except palmitic acid $(C_{16:0})$, while all the parameters were significantly different for seed parts. Significant interactions of variety with seed parts were observed for oleic acid $(C_{18:1})$, $C_{18:2}$ and $C_{18:2}:C_{18:3}$. The highest saturated fatty acid, $C_{18:1}$ and polyunsaturated fatty acid were recorded in seed coat, cotyledon, and seed axis, respectively. The lowest $C_{18:2}:C_{18:3}$ was found in seed axis. In the case of sprout study, variety had significant effect on all the parameters observed for whole sprout, cotyledon, root, and except $C_{18:3}$ for hypocotyl. Culture days had significant effect on $C_{16:0}$, $C_{18:2}$ and $C_{18:3}$ in whole sprouts, while only on $C_{18:3}$ and $C_{18:2}:C_{18:3}$ in cotyledon. For hypocotyl, culture days had significant effect on $C_{18:1}$, $C_{18:2}$ and $C_{18:2}:C_{18:3}$, however, $C_{16:0}$, $C_{18:1}$, $C_{18:3}$, and $C_{18:2}:C_{18:3}$ were significantly different in root. In sprout, days and variety interacted significantly for $C_{16:0}$, $C_{18:3}$ and $C_{18:2}:C_{18:3}$, and $C_{18:1}$, $C_{18:2}$, $C_{18:3}$, and $C_{18:2}:C_{18:3}$, respectively for whole, cotyledon, and root. The significantly lowest $C_{18:2}:C_{18:3}$ (1.1) was observed in hypocotyl and root of Hwangkeumkong in 5 days. Knowledge of fatty acid composition and $C_{18:2}:C_{18:3}$ of seed, sprout, and their parts could be applicable for oil and other soy-food industries to make quality products.