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- 저자 : Jianfeng Li (검색결과 78 건)
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Functionalized multi-wall carbon nanotubes as an efficient additive for electrochemical DNA sensor
Li, Jianfeng,Lee, Eun-Cheol Elsevier Sequoia 2017 Sensors and actuators. B Chemical Vol.239 No.-
<P><B>Abstract</B></P> <P>Functionalized multi-wall carbon nanotubes (FMWCNTs) were used as an additive in electrochemical DNA sensor to modulate the electrochemical current depending on the sequence of the target DNA. This DNA sensing system was simplistically generated by mixing the constituents in a buffer solution, and exhibited good DNA sequence differentiation ability. Compared to the previously reported functionalized graphene (FG) additive, the sample preparation time was reduced from 4h and 20min to 1h, and the detection limit (141.2pM) was reduced by more than two orders of magnitude. When FMWCNT and FG were fabricated <I>via</I> the same functionalization process, suspended FMWCNT sank more rapidly in solution than FG, leading to a shorter reaction time and better DNA detection ability than that obtained with the FG additive.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Functionalized multi-wall carbon nanotubes were used as an additive for electrochemical DNA sensor. </LI> <LI> This sensing system was simplistically generated by mixing all the constituents in a buffer solution. </LI> <LI> The reasonable sample preparation time (1h) and the low detection limit (141.2pM) were achieved. </LI> <LI> This new detection system is promising for applications in fabricating miniaturized biosensors. </LI> </UL> </P>
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Statistical Analysis of Microhardness Variations in Plasma Sprayed $Cr_3C_2-NiCr$ Coatings
Li, Jianfeng,Huang, jingqi,Ding, Chuanxian The Korean Vacuum Society 1998 Applied Science and Convergence Technology Vol.7 No.1
The microstructure and properties of plasma-sprayed coatings depend on a great number of spraying parameters, random factors, which lead to vibration in these spraying parameters, may in some degree influence the microstructure and properties of the coatings. Therefore, the property values appear certain distributions, and the description and comparison of the properties of plasma-sprayed coatings should be performed employing statistical analysis. In this paper, $Cr_3C_2$-Nicr coatings of different thickness were sprayed onto stainless steel using atmosphere plasma system and adopting three kinds of gun translation speeds. Then the microhardness measurements were performed on polished surface of the coatings. Forty readings were taken and statistically analyzed by calculating the characteristic values, estimating and comparing the means, and assessing whether they belonged to the Normal or Weibull Distribution. This study has found that statistical analysis could discriminate influence of spraying parameters and coating design on microhardness of the $Cr_3C_2$-Nicr coatings from random vibration, which showed that the microharness of the $Cr_3C_2$-Nicr coatings were related to gun translation speed coating thickness.
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Jianfeng Li,Junfeng Tong,Peng Zhang,Chunyan Yang,Dejia Chen,Yuancheng Zhu,Yangjun Xia,Duowang Fan 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.2
A new donor-accepter-donor-accepter-donor (D-A-D-A-D) type 2,1,3-benzothiadiazole-thiophene-based acceptor unit 2,5-di(4-(5-bromo-4-octylthiophen-2-yl)-2,1,3-benzothiadiazol-7-yl)thiophene (DTBTTBr2) was synthesized. Copolymerized with fluorene and indeno[1,2-b]fluorene electron-rich moieties, two alternating narrow band gap (NBG) copolymers PF-DTBTT and PIF-DTBTT were prepared. And two copolymers exhibit broad and strong absorption in the range of 300-700 nm with optical band gap of about 1.75 eV. The highest occupied molecular orbital (HOMO) energy levels vary between –5.43 and –5.52 eV and the lowest unoccupied molecular orbital (LUMO) energy levels range from –3.64 to –3.77 eV. Potential applications of the copolymers as electron donor material and PC71BM ([6,6]-phenyl-C71 butyric acid methyl ester) as electron acceptors were investigated for photovoltaic solar cells (PSCs). Photovoltaic performances based on the blend of PF-DTBTT/PC71BM (w:w; 1:2) and PIF-DTBTT/PC71BM (w:w; 1:2) with devices configuration as ITO/ PEDOT: PSS/blend/Ca/Al, show an incident photon-to-current conversion efficiency (IPCE) of 2.34% and 2.56% with the open circuit voltage (Voc) of 0.87 V and 0.90 V, short circuit current density (Jsc) of 6.02 mA/ cm2 and 6.12 mA/cm2 under an AM1.5 simulator (100 mW/cm2). The photocurrent responses exhibit the onset wavelength extending up to 720 nm. These results indicate that the resulted narrow band gap copolymers are viable electron donor materials for polymer solar cells.
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Video Watermarking Algorithm for H.264 Scalable Video Coding
( Jianfeng Lu ),( Li Li ),( Zhenhua Yang ) 한국인터넷정보학회 2013 KSII Transactions on Internet and Information Syst Vol.7 No.1
Because H.264/SVC can meet the needs of different networks and user terminals, it has become more and more popular. In this paper, we focus on the spatial resolution scalability of H.264/SVC and propose a blind video watermarking algorithm for the copyright protection of H.264/SVC coded video. The watermark embedding occurs before the H.264/SVC encoding, and only the original enhancement layer sequence is watermarked. However, because the watermark is embedded into the average matrix of each macro block, it can be detected in both the enhancement layer and base layer after downsampling, video encoding, and video decoding. The proposed algorithm is examined using JSVM, and experiment results show that is robust to H.264/SVC coding and has little influence on video quality.
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Acoustic emission characterization and cracking characteristics of reinforced concrete pipe
Jianfeng Li,Linbing Wang,Dongcan Chen,Yalin Liu,Zhifei Gao,Wentao Wang,Hailu Yang 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.9
Acoustic emission (AE) and digital image correlation (DIC) technology were used in this study to monitor the behavior of reinforced concrete pipe (RCP) in the optimized three-edge bearing test (TEBT). At the same time, the AE source location of different pipe sections was simulated. The results show that the whole compressive loading process for RCP could be divided into 3 to 4 stages. Both the AE counts and AE energy could well characterize the cracking of concrete, and AE energy was more sensitive to the breaking of steel bar. The amplitude and duration of AE signal produced by the breaking of steel bar were larger than those produced by the cracking of concrete. The AE frequency for concrete cracking was relatively scattered. The AE frequency for steel bar breaking was small and concentrated, and this frequency distribution showed an exponential decreasing trend. The results of optimized AE source location showed that the generation and development of cracks occur in the initial loading stage. The results of multi-index analysis showed that the cracks in the top (loading position) and the bottom (bearing position) of the RCP show that the cracks extend from the inner wall to the outer wall, while the cracks on the left and right sides perpendicular to the loading direction show that the cracks extend from the outer wall to the inner wall.
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A New Anthracene-based Small Molecule as Cathode Interlayer for Efficient Polymer Solar Cells
Jianfeng Li,Chuang Zhao,Peng Zhang,Junfeng Tong,Chunyan Yang,Yangjun Xia,Duowang Fan 대한화학회 2015 Bulletin of the Korean Chemical Society Vol.36 No.4
A new small molecule with excellent electron-transporting property, namely 9,10-bis(2-(N-octyl-1,8-naphthalimid-4-yl)ethynyl)anthracene (BNA), is prepared and characterized. A polymer solar cell (PSC) based on poly(3-hexylthiophene) (P3HT) and [6,6]-phenylC61-butyricacidmethyl ester (PC61BM) is also fabricated by using BNA as the cathode buffer layer between the Al electrode and photoactive layer, and their influence on the performance of the PSCs is investigated. It is found that the open-circuit voltage (V oc ), short-circuit current density (J sc ), and power conversion efficiency (PCE) of a device with a 6-nm BNA layer improved to 0.63 V, 9.74 mA/cm2, and 3.74%, respectively, which correspond to an increase of 53.6%, 38.0%, and 177% compared to those without the buffer layer. The BNA buffer layer could effectively improve the interfacial contact performance between the Al electrode and photoactive layer, decrease the series resistance, and improve the collection efficiency of carriers. The devices with appropriate thickness of the BNA buffer layer can also replace the common low-work-function metal Ca for increasing the PCE and lifetime of PSCs.
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Li, Jianfeng,Tong, Junfeng,Zhang, Peng,Yang, Chunyan,Chen, Dejia,Zhu, Yuancheng,Xia, Yangjun,Fan, Duowang Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.2
A new donor-accepter-donor-accepter-donor (D-A-D-A-D) type 2,1,3-benzothiadiazole-thiophene-based acceptor unit 2,5-di(4-(5-bromo-4-octylthiophen-2-yl)-2,1,3-benzothiadiazol-7-yl)thiophene ($DTBTTBr_2$) was synthesized. Copolymerized with fluorene and indeno[1,2-b]fluorene electron-rich moieties, two alternating narrow band gap (NBG) copolymers PF-DTBTT and PIF-DTBTT were prepared. And two copolymers exhibit broad and strong absorption in the range of 300-700 nm with optical band gap of about 1.75 eV. The highest occupied molecular orbital (HOMO) energy levels vary between -5.43 and -5.52 eV and the lowest unoccupied molecular orbital (LUMO) energy levels range from -3.64 to -3.77 eV. Potential applications of the copolymers as electron donor material and $PC_{71}BM$ ([6,6]-phenyl-$C_{71}$ butyric acid methyl ester) as electron acceptors were investigated for photovoltaic solar cells (PSCs). Photovoltaic performances based on the blend of PF-DTBTT/$PC_{71}BM$ (w:w; 1:2) and PIF-DTBTT/$PC_{71}BM$ (w:w; 1:2) with devices configuration as ITO/PEDOT: PSS/blend/Ca/Al, show an incident photon-to-current conversion efficiency (IPCE) of 2.34% and 2.56% with the open circuit voltage ($V_{oc}$) of 0.87 V and 0.90 V, short circuit current density ($J_{sc}$) of $6.02mA/cm^2$ and $6.12mA/cm^2$ under an AM1.5 simulator ($100mA/cm^2$). The photocurrent responses exhibit the onset wavelength extending up to 720 nm. These results indicate that the resulted narrow band gap copolymers are viable electron donor materials for polymer solar cells.
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Tissue-Specific CRISPR/Cas9 System of Cotton Pollen with GhPLIMP2b and GhMYB24 Promoters
Lei Jianfeng,Dai Peihong,Li Jiyang,Yang Mi,Li Xiuqin,Zhang Wanqi,Zhou Guantong,WangzhenGuo,Liu Xiaodong 한국식물학회 2021 Journal of Plant Biology Vol.64 No.1
CRISPR/Cas9 technology is a powerful tool for improving crop genetic traits. However, CRISPR/Cas9 system for efficient expression of cotton germ cells has still not been established. In this study, we developed a tissue-specific vectors to drive Cas9 expression with GhPLIMP2b and GhMYB24 promoters and established the effective method to transform cotton pollen by Agrobacterium vacuum infiltration. GhPLIMP2b and GhMYB24 promoters of cotton pollen were cloned into Cas9 expression vectors. The sgRNAs targetting to CLA1, ERA1 and GGB (drought-resistant negative regulation genes) were designed and constructed into GhPLIMP2b and GhMYB24 promoter vectors. Cotton pollens were tranformed by Agrobacterium vacuum infiltration with GhPLIMP2b and GhMYB24 promoter vectors. The results of clone sequencing shown that mutation types of the sequence were mainly base substitutions wth the frequency from 3.29 to 6.45%. Eleven potential off-target sites were chosen and two sites were observed. Our results indicated that GhPLIM2bP::Cas9 and GhMYB24P::Cas9 editing vectors achieved targeted edition of endogenous genes in cotton pollen, but there were a few off-target effects. This study provides an effective gene-editing system for the rapid acquisition of cotton mutants using pollen as a transgenic receptor.
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