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Wideband Slow Light in a Line-defect Annular Photonic-crystal Waveguide
Feng Kuang,Feng Li,Zhihong Yang,Hong Wu 한국광학회 2019 Current Optics and Photonics Vol.3 No.5
In this theoretical study, a line-defect photonic-crystal waveguide hosted in an annular photonic crystal was demonstrated to provide high-performance slow light with a wide band, low group-velocity dispersion, and a large normalized delay-bandwidth product. Combined with structural-parameter optimization and selective optofluid injection, the normalized delay-bandwidth product could be enhanced to a large value of 0.502 with a wide bandwidth of 58.4 nm in the optical-communication window, for a silicon-on-insulator structure. In addition, the group-velocity dispersion is on the order of 10 5 (ps 2 /km) in the slow-light region, which could be neglected while keeping the signal transmission unchanged.
Influence of Spatial Distribution of Pores on NMR Transverse Relaxation Time in Pebbly Sandstone
Feng Wu,Yanping Xi,Qicheng Fan,Cong Yao,Linlin Cong,Fengsheng Zhang,Yan Kuang 한국자기학회 2019 Journal of Magnetics Vol.24 No.4
The relationship between transverse relaxation time (T₂) and pore size distribution is the basis of NMR applications for rocks. However, the equations for T₂ are not accurate enough in rocks with complicated pore structures. Taking pebbly sandstone from the northwestern Junggar Basin in China as an example, the aim of this study is to discover the spatial distribution of pores and its influence on T₂. Porosity, permeability, micro-images and T₂ distributions were acquired from rock samples, and pore structure parameters were obtained from binarized thin section images. The results show that as the grain size increases, the proportion of dissolution pores increases and the spatial distribution of pores changes from a random to a clustered pattern. The relaxation of a hydrogen atom takes longer and T₂ is higher in dissolution pores compared with those in intergranular pores. New equations for T₂ that consider the spatial distribution of pores are proposed.
Feng Yongjie,Zhang Xing,Kumar Dhiraj,Kuang Sulan,Liu Bo,Hu Xiaolong,Zhu Min,Liang Zi,Cao Guangli,Xue Renyu,Gong Chengliang 한국응용곤충학회 2021 Journal of Asia-Pacific Entomology Vol.24 No.3
Bombyx mori latent virus (BmLV), a novel positive-strand RNA virus was first identified in the B. mori cultured BmN cell line. Whether the infectivity of BmLV to silkworm larvae and non-silkworm cells is connected with dysregulation of gene expression are not well understood. A complete sequence of BmLV genomic RNA was identified and revealed that a fragment with 495 nt in length was deleted from the RNA-dependent RNA poly merase (RdRp) gene in some BmLV genomic RNAs. Studies on the infectivity of BmLV to nontarget cells showed that BmLV can infect silkworm larvae, Spodoptera frugiperda Sf-9 and H1299 lung cancer cells with transient propagation. The dysregulation of gene expression of Sf-9 cells followed by BmLV infection was analyzed. Out of 743 differentially expressed genes (DEGs), 300 were upregulated and 443 were downregulated. Gene Ontology (GO) analysis indicated the DEGs were enriched into oxidoreductase activity for CH-NH 2 group donors, gluta mate biosynthetic process, response to stress and proteasome core complex. KEGG enrichment analysis showed that DEGs were mainly enriched into sulfur metabolism, RNA degradation, proteasome, pentose and glucuronate interconversions. Undesirable nutrients and temperature factors contributed to the propagation of BmLV in Sf-9 cells. Additionally, the Imd and RNAi pathways were activated by BmLV infection without stimulating Toll and JAK-STAT pathways. Therefore, it is suggested that BmLV is originated from plants, which can enter nontarget cells with transient propagation. The transient infection of BmLV may not only be regulated by Imd and RNAi immune pathways but also mediated by dysregulation of gene expression.
Feng Qibo,Zhang Bin,Kuang Cuifang 한국정밀공학회 2008 International Journal of Precision Engineering and Vol.9 No.4
A precision four-degree-of-freedom measurement system has been developed for simultaneous measurement of four motion errors of a linear stage, which include straightness and angular errors. The system employs a retro-reflector to detect the straightness errors and a plane mirror to detect the angular errors. A common-path compensation method for laser beam drift is put forward, and the experimental results show that the influences of beam drift on four motion errors can be reduced simultaneously. In comparison with the API 5D laser measuring system, the accuracy for straightness measurement is about ±1.5㎛ within the measuring range of ±650㎛, and the accuracy for pitch and yaw measurements is about ± 1.5arc-seconds within the range of ±600arc-seconds.
Qibo, Feng,Bin, Zhang,Cuifang, Kuang Korean Society for Precision Engineering 2008 International Journal of Precision Engineering and Vol.9 No.4
A precision four-degree-of-freedom measurement system has been developed for simultaneous measurement of four motion errors of a linear stage, which include straightness and angular errors, The system employs a retro-reflector to detect the straightness errors and a plane mirror to detect the angular errors. A common-path compensation method for laser beam drift is put forward, and the experimental results show that the influences of beam drift on four motion errors can be reduced simultaneously. In comparison with the API 5D laser measuring system, the accuracy for straightness measurement is about ${\pm}1.5{\mu}m$ within the measuring range of ${\pm}650{\mu}m$, and the accuracy for pitch and yaw measurements is about ${\pm}1.5$ arc-seconds within the range of ${\pm}600$ arc-seconds.
Effects of Neodymium and Calcium on the Thermal Stability of AZ71 Magnesium Alloys
Cheng‑Feng Yue,Shi‑Jei Huang,Jhewn‑Kuang Chen,Hsien‑Tsung Li,Kam‑Shau Chan 대한금속·재료학회 2018 METALS AND MATERIALS International Vol.24 No.2
The effects of an addition of 0–2 wt% Nd on thermal stability of 0–3 wt% Ca-containing modified AZ71 magnesium alloyswas investigated. The ignition temperature was found to increase from that of AZ71, 574, to 825 °C with the addition of0.5 wt% Ca and 1 wt% Nd. The ignition temperature was further increased to 1114 °C when 3 wt% Ca was added. The CaandNd-added AZ71 was isothermally maintained at a temperature of 500 °C in air for 12 h. The MgO–CaO–Nd2O3 formedon the surface to improve the thermal stability of the AZ71–xCa–yNd alloys. While both the tensile strength and ductilitydecreased with the Ca concentration in the alloy, an addition of 1 wt% Nd was found able to alleviate the degradation effectsof Ca on the tensile strength and ductility at 170 °C. Both solid solution formation and precipitation strengthening contributedto the increase in toughness. AZ71 containing 0.5–2 wt% Ca and 1 wt% Nd provides the optimum combination of ignitionresistance and mechanical properties.
Chemical Constituents from the Flower of Datura metel L.
Hai-xue Kuang,Bing-you Yang,Yong-gang Xia,Wei-sheng Feng 대한약학회 2008 Archives of Pharmacal Research Vol.31 No.9
Phytochemical investigation of the 50% ethanol eluate fraction of macroporous resin for the flower of Datura metel L. led to the isolation of a new compound named yangjinhualine A (1) and five known megastigmane sesquiterpenes through repeated silica gel and ODS column chromatography and semipreparative HPLC. The structures of these compounds were determined by spectroscopic methods, including 2D-NMR, ESI-MS, and HR-ESI-MS spectrometry as well as by comparison with published data. Five known megastigmane sesquiterpenes were also isolated from D. metel L. for the first time.
Li, Junhua,Kuang, Daizhi,Feng, Yonglan,Zhang, Fuxing,Xu, Zhifeng,Liu, Mengqin Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.8
A novel and convenient electrochemical method has been developed for sensitive determination of melamine (MEL) using ascorbic acid (AA) as the recognition element. The working electrode employed in this method was modified with the nanocomposite of hydroxyapatite/carbon nanotubes to enhance the current signal of recognition element. The interaction between MEL and AA was investigated by fourier transform infrared spectroscopy and cyclic voltammetry, and the experimental results indicated that hydrogen bonding was formed between MEL and AA. Because of the existing hydrogen bonding and electrostatic interaction, the anodic peak current of AA was decreased obviously while the non-electroactive MEL added in. It illustrated that the MEL acted as an inhibitor to the oxidation of AA and the decreasing signals can be used to detect MEL. Under the optimal conditions, the decrease in anodic peak current of AA was proportional to the MEL concentrations ranging from 10 to 350 nM, with a detection limit of 1.5 nM. Finally this newly-proposed method was successfully employed to detect MEL in infant formula and milk, and good recovery was achieved.