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排序方式: 共有165条查询结果,搜索用时 15 毫秒
91.
Jiyeon Kweon An-Hee Jang Eunji Kwon Ungi Kim Ha Rim Shin Jieun See Gayoung Jang Chaeyeon Lee Taeyoung Koo Seokjoong Kim Yongsub Kim 《Experimental & molecular medicine》2023,55(2):377
Various CRISPR‒Cas9 orthologs are used in genome engineering. One of the smallest Cas9 orthologs is cjCas9 derived from Campylobacter jejuni, which is a highly specific genome editing tool. Here, we developed cjCas9-based base editors including a cytosine base editor (cjCBEmax) and an adenine base editor (cjABE8e) that can successfully induce endogenous base substitutions by up to 91.2% at the HPD gene in HEK293T cells. Analysis of the base editing efficiency of 13 endogenous target sites showed that the active windows of cjCBEmax and cjABE8e are wider than those of spCas9-based base editors and that their specificities are slightly lower than that of cjCas9. Importantly, engineered cjCas9 and gRNA scaffolds can improve the base editing efficiency of cjABE8e by up to 6.4-fold at the HIF1A gene in HEK293T cells. Due to its small size, cjABE8e can be packaged in a single adeno-associated virus vector with two tandem arrays of gRNAs, and the delivery of the resulting AAV could introduce base substitutions at endogenous ANGPT2 and HPD target sites. Overall, our findings have expanded the potential of the use of base editors for in vivo or ex vivo therapeutic approaches.Subject terms: Genetic engineering, Gene therapy 相似文献
92.
We show that supersymmetry may play an important role in giving a reasonable explanation of relevant cosmological features. We work in a classicalN=1 supergravity scenario showing that supersymmetric matter leads, in the classical limit, to a fluid model acting as the source of the gravitational field. The equation of state arises, in a natural way, as a consequence of the field equations. We study conditions for the matter dominated era and the existence of an inflationary solution. Using upper bounds of several red-shift experimental results we are able to give an estimate of the corresponding Hubble constant. 相似文献
93.
We report the influence of composition and very high transverse field annealing on the magnetic properties and structure of four FeCo-based amorphous and nanocrystalline alloys. The compositions (Fe50Co50)89Zr7B4 and (Fe65Co35)89Zr7B4 were investigated changing the Fe:Co ratio from 50:50 to 65:35. (Fe50Co50)85Zr2Nb4B8.5 was chosen to investigate Nb substitution for Zr in an FeCo-based alloy. This substitution is shown to increase the magnetostrictive constant, λS, of the nanocrystalline alloy from 36×10−6 to 54×10−6. The composition (Fe65Co35)84Cr5Zr7B4 was studied to investigate the influence of Cr on intergranular coupling across the amorphous matrix. Samples of each composition were annealed in the amorphous state at 300 °C and in the nanocrystalline state at 600 °C. Field annealing was performed in 17 T transverse field in an inert atmosphere. Frequency-dependent magnetic properties were measured with an automatic recording hysteresisgraph. Static magnetic properties were measured with a vibrating sample magnetometer. The mass-specific power loss of the alloys decreased with field annealing in both the nanocrystalline and amorphous states for some frequency and induction combinations. Furthermore, the hysteresis loops are sheared after field annealing, indicating a transverse magnetic anisotropy. The nanocrystalline (Fe50Co50)85Zr2Nb4B8.5 composition has a lower relative permeability than the other compositions. 相似文献
94.
95.
BalSang Lee In Hyeok Jang Jong Wook Bae Soong Ho Um Pil J. Yoo Myung-June Park Yong Chul Lee Ki-Won Jun 《Catalysis Surveys from Asia》2012,16(3):121-137
The present paper represents the promising ways to improve catalytic performance by introducing zirconium phosphate (ZP) on Ru/Co/SiO2 catalysts and the related kinetic models using the optimized Fischer?CTropsch synthesis (FTS) catalyst. A lot of works has been reported using cobalt-based catalyst for FTS reaction, and many authors have continuously tried to find out highly efficient FTS catalyst by modifying support as well as by introducing promoters. Silica is one of the excellent candidates as catalytic supports, and the present works intensively represents how to modify SiO2 support for a high catalytic performance by using ZP species. The effect of ZP-modification of SiO2 support with respect to cobalt aggregation and catalytic deactivation was mainly investigated for FTS reaction. The surface modification at P/(Zr?+?P) molar ratio between 0.029 and 0.134, enhanced the spatial confinement effect of cobalt clusters, and resulted in high catalytic stability with the help of well-dispersed ZP particle formation. The enhanced catalytic performance, in terms of CO conversion, C5+ selectivity and catalytic stability, is mainly attributed to the suppressed aggregation, a homogeneous distribution of cobalt clusters with a proper size and a low mobility of cobalt clusters at an optimum molar ratio of P/(Zr?+?P) because of the formation of thermally stable ZP particles. The kinetic parameters and rate equations on the optimized catalyst are also derived in terms of CO conversion and product distribution. 相似文献
96.
Sun-Ae Jun Chuloo Moon Cheol-Hee Kang Sean W. Kong Byoung-In Sang Youngsoon Um 《Applied biochemistry and biotechnology》2010,161(1-8):491-501
The production of 1,3-propanediol (1,3-PD) was investigated with Klebsiella pneumoniae DSM 4799 using raw glycerol without purification obtained from a biodiesel production process. Fed-batch cultures with suspended cells revealed that 1,3-PD production was more effective when utilizing raw glycerol than pure glycerol (productivity after 47 h of fermentation, 0.84 g?L?1?h?1 versus 1.51 g?L?1?h?1 with pure and raw glycerol, respectively). In addition, more than 80 g/L of 1,3-PD was produced using raw glycerol; this is the highest 1,3-PD concentration reported thus far for K. pneumoniae using raw glycerol. Repeated fed-batch fermentation with cell immobilization in a fixed-bed reactor was performed to enhance 1,3-PD production. Production of 1,3-PD increased with the cycle number (1.06 g?L?1?h?1 versus 1.61 g?L?1?h?1 at the first and fourth cycle, respectively) due to successful cell immobilization. During 46 cycles of fed-batch fermentation taking place over 1,460 h, a stable and reproducible 1,3-PD production performance was observed with both pure and raw glycerol. Based on our results, repeated fed batch with immobilized cells is an efficient fermentor configuration, and raw glycerol can be utilized to produce 1,3-PD without inhibitory effects caused by accumulated impurities. 相似文献
97.
Using quartz crystal microbalance (QCM) as an immunosensor, this work investigates the contribution of a cyclic voltammetry (CV) on the proper immobilization of antibodies with the aim of enhancing its target recognition and binding ability. Primarily, CV in the range of −0.1 to 0.9 V was applied to form a layer of poly-(2-cyano-ethylpyrrole) (PCEPy) on gold quartz crystal electrode. Then the efficiencies of antibodies (anti-IgG, AIgG) immobilized electrochemically with CV applied in 0-0.65 V were compared to those immobilized via physical adsorption, by observing relative affinity towards AIgG-Fab and AIgG-Fc fragments. The results showed antibody-AIgG-Fab interaction could be enhanced about 4 times when CV is applied (11.2 ± 1.3 vs 41.6 ± 3.4 relative fluorescence unit). On the contrary, physisorbed antibodies showed a higher degree of affinity towards AIgG-Fc indicating inappropriate orientations of physisorbed antibodies. AIgG immobilized PCEPy-gold QC electrode was characterized further for its sensitivity towards a new target bovine albumin with both a QCM and fluorescence measurement. Such electrode exhibited a good sensitivity as well as a large linear dynamic range, from 0.4 μg/ml to 1.0 μg/ml and from 0.5 μg/ml to 10.0 μg/ml, at QCM and fluorescence measurement, respectively. 相似文献
98.
Um SY Kim KB Kim SH Ju YC Lee HS Oh Hy Choi KH Chung MW 《Journal of separation science》2008,31(15):2820-2826
A simple and direct analysis using column-switching HPLC method was developed and validated for the quantification of active metabolites of sibutramine, N-mono-desmethyl metabolite (metabolite 1, M1) and N-di-desmethyl metabolite (metabolite 2, M2) in the serum of rats administered sibutramine HCl (5.0 mg/kg, p.o.). Rat serum was directly injected onto the precolumn without sample prepreparation step following dilution with mobile phase A, i. e., methanol-ACN-20 mM ammonium phosphate buffer (pH 6.0 with phosphoric acid) (8.3:4.5:87.2 by volume). After the endogenous serum components were eluted to waste, the system was switched and the analytes were eluted to the trap column. Active metabolites M1 and M2 were then back-flushed to the analytical column for separation with mobile phase B, i. e., methanol-ACN-20 mM ammonium phosphate buffer (pH 6.0 with phosphoric acid) (35.8:19.2:45 by volume) and detected at 223 nm. The calibration curves of active metabolites M1 and M2 were linear in the range of 0.1-1.0 microg/mL and 0.15-1.8 microg/mL. This method was fully validated and shown to be specific, accurate (10.4-10.7% error), and precise (1.97-8.79% CV). This simple and rapid analytical method using column-switching appears to be useful for the pharmacokinetic study of active metabolites (M1 and M2) of sibutramine. 相似文献
99.
Won-Sang Chung Ki-Soo Chung Sang-Tack Nam Chung-In Um 《International Journal of Theoretical Physics》1994,33(4):797-803
We obtain the commutation relation between rows and columns ofN ×N quantum matrices. We derive the quantum determinant and discuss its property in terms of the q-deformed Levi-Civita symbol. We find the inverse and trace ofN×N quantum matrices. Finally we discuss the q-deformed complexification of the quantum matrices. 相似文献