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Fengping Ye,Qili Mi,Ning Zhang,Xuemei Li,Jing Yu,Zhongping Gao,Ying Zheng,Quanshui Fan,Jie Wang,Jinglin Wang 대한화학회 2016 Bulletin of the Korean Chemical Society Vol.37 No.5
Chemical modifications of the nucleotides can improve the stability of aptamers against enzyme degradation in serum, but it is not clear whether these methods are effective in snake venom. In this study, a DNA aptamer, βB-1, which specifically recognize β-bungarotoxin and Bungarus multicinctus venom was chosen, and the key binding sequence of the aptamer was determined. Based on the secondary structure of the truncated aptamer, locked nucleic acids and 2′-O-methyl nucleotides were applied to modify the stem and loop sequences, respectively. In addition, a 3′-3′-thymidine cap was also adopted to block the 3′ end. It was shown that these chemical modifications can all enhance the stability of the aptamer in snake venom. Simultaneously, modified aptamer with the above modifications in one sequence exhibited a significantly elevated biostability, with the half-life improved from several minutes to 210 min while maintaining its binding affinity to the target.
Yuhang Wang,Dongyong Li,Xubo Lai,Boyang Liu,Yibao Chen,Fengping Wang,Rongming Wang,Liuwan Zhang 한국물리학회 2020 Current Applied Physics Vol.20 No.2
The hysteresis in the transfer curve of MoS2 has significant impact on the device performance. However, the hysteresis mechanism is still not clear. Here, we investigate the hysteresis of the monolayer MoS2 by probing the local Fermi level variations as a function of the back gate voltage in different atmosphere using the Kelvin probe microscopy. While the Fermi level of the MoS2 in air is much lower than that in vacuum, both the MoS2 devices in vacuum and air show large Fermi level hysteresis. The Fermi level hysteresis direction is clock-wise, identical to that observed in the transfer curves. Both the hysteresis in Fermi level and transfer curve can be explained consistently by taking into account the charge trapping. Our findings confirm that carrier density modulation in MoS2 plays a vital role in the hysteresis, and provide insight into the hysteresis mechanism for the optimization of the device performance.
Huang, Fengping,Wang, Shuai,Zhang, Shuang,Fan, Yingge,Li, Chunxue,Wang, Chuang,Liu, Chun Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.8
The praseodymium-doped $TiO_2$ photocatalyst samples, which could degrade methyl orange under UV irradiation, were prepared by sol-microwave method for improving the photocatalytic activity of $TiO_2$. The resulting materials were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectra, Fourier transform infrared spectra (FTIR) and Ultraviolet-visible diffuse reflectance spectra (UV-vis DRS). It was found Pr doping retarded the growth of crystalline size and the phase transformation from anatase to rutile, and narrowed the band gap energy. Praseodymium doping brought about remarkable improvement in the photoactivity. The optimal dopant amount of Pr was 2% by molar of cement and the calcination temperature was $500^{\circ}C$ for the best photocatalytic activity. The improvement of photocatalytic activity was ascribed to the occurrence of lattice distortion and the effective containment of the recombination of the electron-hole by $Pr^{3+}$.
Pavement Crack Detection by Ridge Detection on Fractional Calculus and Dual-thresholds
Song Hongxun,Wang Weixing,Wang Fengping,Wu Linchun,Wang Zhiwei 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.4
In this paper, a new road surface crack detection algorithm is proposed; it is based on the ridge edge detection on fractional calculus and the dual-thresholds on a binary image. First, the multi-scale reduction of image data is used to shrink an original image to eliminate noise, which can not only smooth an image but also enhance cracks. Then, the main cracks are extracted by using the ridge edge detection on fractional calculus in a grey scale image. Subsequently, the resulted binary image is further processed by applying both short and long line thresholds to eliminate short curves and noise for getting rough crack segments. Finally the gaps in cracks are connected with a curve connection function which is an artificial intelligence routine. The experiments show that the algorithm for pavement crack images has the good performance of noise immunity, accurate positioning, and high accuracy. It can accurately locate and detect small and thin cracks that are difficult to identify by other traditional algorithms.
A New Cytotoxic Phenazine Derivative from a Deep Sea Bacterium Bacillus sp.
Dehai Li,Fengping Wang,Xiang Xiao,Xiang Zeng,Qian-Qun Gu,Weiming Zhu 대한약학회 2007 Archives of Pharmacal Research Vol.30 No.5
A novel phenazine derivative (1) together with six known compounds (2-7) were isolated by bioassay-guided fractionation from the culture broth of a bacterium, Bacillus sp., collected from a Pacific deep sea sediment sample (depth 5059 m). The structures of these compounds were determined using spectroscopic methods. Their cytotoxic effects on P388 and K562 cell lines were preliminarily examined using the sulforhodamine-B (SRB) assay.
Measurement of Road Surface Irregular Crack Width Based on Ferret and Second Order Moment
Liu Sheng,Wang Weixing,Wang Fengping 보안공학연구지원센터 2016 International Journal of Signal Processing, Image Vol.9 No.12
In order to evaluate the damage of the road accurately, a Ferret subsection measurement method based on Invariantmoment was proposed. First, it set a Ferret minimum external rectangular on the basis of the barycenter and spindle. The rectangular width was the result of crack width. It set the edge conditions for reducing the errors of measurement caused by the slender burrs. It allowed rectangular edge and targets to intersect. In order to section reasonably, a method based on distance map was proposed. In the extreme value points, the subsections image was finished. It ensured that the distance between two adjacent lines was longer than the crack width. Experimental data indicated that the percent of valuable information was higher, the measurement was accurate. It can meet the requirement of practical engineering.
Ying Hou,Fengping Wang,Zhilei Tan,Jiandong Cui,Shiru Jia 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.3
ε-Poly-L-lysine (ε-PL) is a natural antimicrobial cationic peptide. Antimicrobial activity of ε-PL is closely related to its molecular weight (Mw). However, the antimicrobial mechanisms of ε-PL with different Mws are still vague. In this study, Saccharomyces cerevisiae was used as the model system to analyze the mechanism from these three aspects: cell wall, cell membrane, and metabolism. The results showed that high-Mw ε-PL (1-3 kDa and >3 kDa) and commercial ε-PL product caused cell wall lesions, and significantly improved cell membrane permeability compared to low-Mw ε-PL (<1 kDa), resulting in leaking of the protoplasm through the pores and cell death. Furthermore, metabolomics analysis showed that high-Mw ε-PL (1-3 kDa and >3 kDa) and product displayed higher inhibition effect on the glycolysis pathway and tricarboxylic cycle than that of low-Mw ε-PL (<1 kDa).
A New Cytotoxic Phenazine Derivative from a Deep Sea Bacterium Bacillus sp
Zhu, Weiming,Li, Dehai,Wang, Fengping,Xiao, Xiang,Zeng, Xiang,Gu, Qian-Qun 대한약학회 2007 Archives of Pharmacal Research Vol.30 No.5
A novel phenazine derivative (1) together with six known compounds (2-7) were isolated by bioassay-guided fractionation from the culture broth of a bacterium, Bacillus sp., collected from a Pacific deep sea sediment sample (depth 5059 m). The structures of these compounds were determined using spectroscopic methods. Their cytotoxic effects on P388 and K562 cell lines were preliminarily examined using the sulforhodamine-B (SRB) assay.
Keguang Han,Jing Cao,Jinghui Wang,Jing Chen,Kai Yuan,Fengping Pang,Shaopeng Gu,Nairui Huo 한국축산식품학회 2018 한국축산식품학회지 Vol.38 No.6
Both the calcium and collagen in bone powder are hard to be absorbed by the body. Although enzymatic hydrolysis by protease increased the bio-availability of bone powder, it was a meaningful try to further increase Ca2+ release, oligopeptide formation and antioxidant activity of the sheep bone hydrolysate (SBH) by lactic acid bacteria (LAB) fermentation. Lactobacillus helveticus was selected as the starter for its highest protease-producing ability among 5 tested LAB strains. The content of liberated Ca2+ was measured as the responsive value in the response surface methodology (RSM) for optimizing the fermenting parameters. When SBH (adjusted to pH 6.1) supplemented with 1.0% glucose was inoculated 3.0% L. helveticus and incubated for 29.4 h at 36℃, Ca2+ content in the fermented SBH significantly increased (p<0.01), and so did the degree of hydrolysis and the obtaining rate of oligopeptide. The viable counts of L. helveticus reached to 1.1×1010 CFU/mL. Results of Pearson correlation analysis demonstrated that LAB viable counts, Ca2+ levels, obtaining rates of oligopeptide and the yield of polypeptide were positively correlated with each other (p<0.01). The abilities of SBH to scavenge the free radicals of DPPH, OH and ABTS were also markedly enhanced after fermentation. In conclusion, L. helveticus fermentation can further boost the release of free Ca2+ and oligopeptide, enhance the antioxidant ability of SBH. The L. helveticus fermented SBH can be developed as a novel functional dietary supplement product.
Effect of strain amplitude and temperature on creep-fatigue behaviors of 9-12 % Cr steel
Jianfeng Mao,Jian Zhu,Xiangyang Li,Dasheng Wang,Fengping Zhong,Jichang Chen 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.5
The creep-fatigue behaviors of P92 steel under strain range of 0.3 %-0.5 % and test temperature of 600-650 °C was studied carefully in this paper. With the increase of temperature, the creep-fatigue life is significantly reduced, and more vulnerable to temperature than strain amplitude. In addition, the dislocation density decreases with increasing creep fatigue, and the martensite laths become coarser. Furthermore, the increase of strain amplitude leads to more significant secondary cracks and fatigue striation. The higher temperature causes much deeper and larger dimples. During the test, the growth and accumulation of precipitates inevitably lead to stress concentration, resulting in material fracture and destruction. Finally, the linear cumulative damage (LCD), the modified ductility exhaustion (MDE) and the frequency separation life (FSL) model are used to predict the creep-fatigue life of P92 steel, and it is found that the frequency separation life model had the highest prediction accuracy among the threes.