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CRISPR as a strong gene editing tool
( Shengfu Shen ),( Tiing Jen Loh ),( Hongling Shen ),( Xuexiu Zheng ),( Haihong Shen ) 생화학분자생물학회(구 한국생화학분자생물학회) 2017 BMB Reports Vol.50 No.1
Clustered regularly-interspaced short palindromic repeats (CRISPR) is a new and effective genetic editing tool. CRISPR was initially found in bacteria to protect it from virus invasions. In the first step, specific DNA strands of virus are identified by guide RNA that is composed of crRNA and tracrRNA. Then RNAse III is required for producing crRNA from pre-crRNA. In The second step, a crRNA:tracrRNA:Cas9 complex guides RNase III to cleave target DNA. After cleavage of DNA by CRISPR-Cas9, DNA can be fixed by Non- Homologous End Joining (NHEJ) and Homology Directed Repair (HDR). Whereas NHEJ is simple and random, HDR is much more complex and accurate. Gene editing by CRISPR is able to be applied to various biological field such as agriculture and treating genetic diseases in human. [BMB Reports 2017; 50(1): 20-24]
Liu Shengfu,Jin Xiaoliang,Shi Wen,Yang Huan,Zhao Rongxiang 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.1
The modulation’s eff ects on the stator losses have been explored by previous studies. It confi rms that the voltage vector error introduced by the PWM schemes dominants the PWM-related harmonic eddy-current loss and the PWM-related harmonic copper loss. However, the existing PWM schemes of two parallel inverter focus on the ZSCC peak reductions. They do not explore the reductions of the voltage vector error by the optimal vector sequences to suppress the stator loss. This paper aims to reduce the stator loss of the permanent magnet synchronous motor (PMSM) drive systems fed by the two parallel interleaved inverter with an optimal PWM scheme. First, this paper investigates the eff ects of the instantaneous voltage vector error, resulting from a PWM inverter, on the eddy-current loss and stator copper loss and reveals that a reduced voltage error reduces the eddy-current loss and stator copper loss. Then, this paper divides each 60° sector into six subsectors to minimize the voltage vector error, and with the proposed sector division, it further elects the optimal vector sequences for the subsectors, applying the minimum switching times per carrier period. Besides, the proposed optimal vector sequences are implemented through a simplifi ed carrier-based method. The presented analysis confi rms that the proposed PWM scheme can reduce the eddy-current loss, stator copper loss, and switching loss of the existing methods. Finally, the experimental results verify the theoretical analysis and optimal performance of the proposed modulation strategy.
A new peptide-mediated COF nanocatalytic amplification SERS quantitative assay for ultratrace Cu2+
Yiyi Shu,Shengfu Zhi,Sha Li,Aihui Liang,Zhiliang Jiang 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.113 No.-
Peptides are an important recognition element for small molecules and have been used in the field of biologicalanalysis. However, it has been rarely reported that a novel method combining peptides as recognitionelements with covalent organic framework (COF) as catalytic amplification signal to constructhighly sensitive and selective three-mode molecular spectroscopy. In this paper, high catalytic and stablethree COFs were prepared, and the catalysis of the new indicator nanoreaction of HAuCl4-sodiumformate(Fo) was studied by molecular spectral slope procedure. The produced gold nanoparticles (AuNPs) exhibita strong resonance Rayleigh scattering (RRS) peak at 370 nm and surface plasmon resonance absorption(Abs) peak at 540 nm. In the presence of molecular probes, a strongest surface-enhanced Raman scattering(SERS) peak was generated at 1617 cm1. Combining the COFTpBD amplification indicator reactionwith specific peptide (PT) reaction of Cu2+, a novel, sensitive and selective SERS/RRS/Abs assay platformwas established, with a SERS linear range of 0.005–0.115 nmol/L Cu2+. In addition, the two workingcurves of lg[Cu2+] vs SERS and [Cu2+] vs SERS intensity, and the nanocatalytic mechanism were discussed.
Wenqian Zhao,Richie Yang,Shengfu Yang,Kan Zhang 한국고분자학회 2023 Macromolecular Research Vol.31 No.1
We observed an unusual low polymerization temperature for the ortho-amide benzoxazine in comparison with its para-isomer. Density functional theory (DFT) calculations suggested that the intramolecular hydrogen bond between the oxazine ring and the adjacent amide softens the C–O bond, resulting in a reduced activation energy and thus a low ring-opening polymerization temperature. In addition, the polymerization kinetics of both para- and ortho-amide functional benzoxazines were investigated using the Starink method, which confirmed a relatively lower activation energy for the ortho-amide functional benzoxazine compared with its para-isomer. Our work suggests that softening chemical bonds by intramolecular hydrogen bonding may become a new strategy for the design of high-performance polybenzoxazine thermosets with low processing temperatures.
Developmental Stages of Akebia trifoliata Fruit Based on Volume
Hao Yang,Wei Chen,Peng Fu,Shengfu Zhong,Ju Guan,Peigao Luo 한국원예학회 2021 원예과학기술지 Vol.39 No.6
Akebia trifoliata, commonly named augmelon (means August plus melon), has been domesticating as a new artificial cultivation fruit crop in China for several years. Generally, field management measurements are severely dependent on the development dynamic of harvest organs, and therefore the study of fruit development stage of A. trifoliata is urgent in production. In this study, four cloned lines with various spindle, nephroid, pyriform and Banana-like shapes, were selected to observe fruit developmental parameters, including volume, weight, length and width from pollination to maturity. Volume rather than length or width, which can minimize the influence of fruit shape on growth stage, was finally employed as a primary parameter for dividing developmental stages. Then a Logistic model of volume growth was established according to the data of pyriform fruit, and the other three fruits were employed to the suitability of this mathematical model. The resulted showed that the growth curve of augmelon appeared typical double sigmoid shape for all four shapes fruits. Based on four inflection points of volume growth curve, the fruit development of augmelon was classified five developmental stages in the order: fast stretch (FS) stage lasting for 48 days, shape stabilization (SS) stage lasting for 30 days, tardy expansion (TE) stage lasting for 51 days, suspended expansion (SE) stage lasting for 21 days and fast expansion (FE) stage lasting for 30 days. Comprehensively, volume was an ideal growth parameter for dividing fruit developmental stage of augmelon, and five-stage growth model could be applied as reference for both gardener and scientist to refer to the fruit growth status.
SR proteins regulate V6 exon splicing of CD44 pre-mRNA
( Tiing Jen Loh ),( Heegyum Moon ),( Ha Na Jang ),( Yongchao Liu ),( Namjeong Choi ),( Shengfu Shen ),( Darren Reece Williams ),( Da-woon Jung ),( Xuexiu Zheng ),( Haihong Shen ) 생화학분자생물학회(구 한국생화학분자생물학회) 2016 BMB Reports Vol.49 No.11
CD44 pre-mRNA includes 20 exons, of which exons 1-5 (C<sub>1</sub>-C<sub>5</sub>) and exons 16-20 (C<sub>6</sub>-C<sub>10</sub>) are constant exons, whereas exons 6-15 (V<sub>1</sub>-V<sub>10</sub>) are variant exons. V6-exon-containing isoforms have been known to be implicated in tumor cell invasion and metastasis. In the present study, we performed a SR protein screen for CD44 V<sub>6</sub> splicing using overexpression and lentivirus-mediated shRNA treatment. Using a CD44 V<sub>6</sub> minigene, we demonstrate that increased SRSF3 and SRSF4 expression do not affect V<sub>6</sub> splicing, but increased expression of SRSF1, SRSF6 and SRSF9 significantly inhibit V<sub>6</sub> splicing. In addition, using a constitutive exon-specific primer set, we could not detect alterations of CD44 splicing after SR protein-targeting shRNA treatment. However, using a V<sub>6</sub> specific primer, we identified that reduced SRSF2 expression significantly reduced the V6 isoform, but increased V<sub>6-10</sub> and V<sub>6,8-10</sub> isoforms. Our results indicate that SR proteins are important regulatory proteins for CD44 V<sub>6</sub> splicing. [BMB Reports 2016; 49(11): 612-616]
Porosity in fiber laser formation of 5A06 aluminum alloy
Yangchun Yu,Chunming Wang,Xiyuan Hu,Jun Wang,Shengfu Yu 대한기계학회 2010 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.24 No.5
The mechanism of porosity formation and its suppression methods in laser formation of aluminum alloy have been studied using a 4kW fiber laser to weld 5A06 aluminum alloy with SAl-Mg5 filler. It was found that the porosity formation is closely related to the stability of the keyhole and fluctuation of the molten pool in the laser welding aluminum alloy. The filling wire increased the instability of the keyhole and weld pool, thus further increasing the amount of gas cavities in the joint. Prefabrication of a suitable gap for the butt joint can provide a natural passage for the flow of the liquid metal, which can weaken, and even completely eliminate the disturbance of the filling wire on the formation of keyhole. The gap can also provide a passage for the escape of the bubble. Thus, this method can greatly decrease the sheet’s susceptibility to porosity. Moreover, for a thin sheet, if the power of the laser is sufficient to form a keyhole with stable penetration through the weld sheet, a weld bead without porosity can also be obtained because closing the keyhole is almost impossible.
Interaction between laser-induced plasma/vapor and arc plasma during fiber laser-MIG hybrid welding
Jun Wang,Chunming Wang,Xuanxuan Meng,Xiyuan Hu,Yangchun Yu,Shengfu Yu 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.6
Hybrid plasma is an important physical phenomenon in fiber laser-MIG hybrid welding. It greatly affects the stability of the process,the quality of the weld, and the efficiency of energy coupling. In this paper, clear and direct proofs of these characteristics are presented through high-speed video images. Spectroscopic analysis is used to describe the characterization of hybrid plasma. The hybrid plasma forms a curved channel between the welding wire and the keyhole during the fiber laser-MIG hybrid welding process. The curved channel is composed of two parts. The laser-induced plasma/vapor expands due to the combined effect of the laser and the MIG arc, forming an ionization duct, which is one part of the curved channel. The resistance of the duct is smaller than that of other locations because of the rise in electrical conductivity. Consequently, the electrical arc is guided through the duct to the surface of the material, which is the other part of the curved channel. The spectral intensities of metal elements in laser-MIG hybrid welding are much stronger than those in MIGonly welding, whereas the spectral intensities of shielding gas element in laser-MIG hybrid welding are much weaker.
Xiaoyu Zhang,Liyuan Fan,Yanshuai Cui,Tianming Cui,Shengfu Chen,Guanglong Ma,Wenlong Hou,Longgang Wang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2020 NANO Vol.15 No.02
The green synthesis of gold nanoparticles (Au NPs) for catalytic and biological applications has been drawing great attention. To compare with plant extracts, the polysaccharides may be good reducing and stabilizing agents. In this work, we describe the preparation of longan polysaccharide stabilized gold nanoparticles (Aun-LP NPs) by reduction of gold ions using a green synthetic method. The formation of gold nanoparticles (Au NPs) was confirmed by UV-Vis spectra. TEM showed that Au NPs had a small size (7.8–15.6 nm) and were highly dispersed without any aggregation. XPS confirmed that the surface elemental composition of Aun-LP NPs was C, O, and Au. DLS demonstrated that Aun-LP NPs had good stability and negative zeta potential. In addition, Aun-LP NPs had high catalytic activity for the reduction of 4-nitrophenol. More importantly, Aun-LP NPs had ignorable cytotoxicity towards HeLa cells and showed good antioxidant activity. Taken together, the results indicated that longan polysaccharide can be used as reducing agents and stabilizers for the preparation of metallic nanoparticles, and the product had wide applications.
Investigation of melting dynamics of filler wire during wire feed laser welding
Yangchun Yu,Wei Huang,Guozhen Wang,Jun Wang,Xuanxuan Meng,Chunming Wang,Fei Yan,Xiyuan Hu,Shengfu Yu 대한기계학회 2013 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.27 No.4
In order to investigate the mechanism of stability for the wire feed laser welding process, systematic experiments are carried out in this study for 5A06 aluminum alloy. By using high speed camera, the melting dynamics of filler wires with different feed positions and feed rates are studied. The results indicate that these two factors mainly influence the characteristics of the filler wire melting dynamics and determine the stability of the welding process. The melting dynamics of filler wire can be generally characterized by three different forms: explosion, big droplet and molten metal bridge. When the filler wire melts and transits to the molten pool in the forms of explosion or big droplet, the stability of the welding process is strongly disturbed, resulting in an undesirable weld quality. In contrast, when it is in molten metal bridge form, the welding process is more stable and a uniform weld bead is achieved.