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21.
Dr. Fengqin Li Junru Li Weiqiang Yang Dr. Shuai Yang Congshuo Chen Ling Du Junyang Mei Dr. Qianyun Tang Xiaojing Chen Dr. Chi Yao Prof. Dayong Yang Prof. Xiaolei Zuo Prof. Peifeng Liu 《Angewandte Chemie (International ed. in English)》2023,62(32):e202305536
The trans-cleavage property of CRISPR-Cas12a system makes it an excellent tool for disease diagnosis. Nevertheless, most methods based on CRISPR-Cas system still require pre-amplification of the target to achieve the desired detection sensitivity. Here we generate Framework-Hotspot reporters (FHRs) with different local densities to investigate their effect on trans-cleavage activity of Cas12a. We find that the cleavage efficiency increases and the cleavage rate accelerates with increasing reporter density. We further construct a modular sensing platform with CRISPR-Cas12a-based target recognition and FHR-based signal transduction. Encouragingly, this modular platform enables sensitive (100 fM) and rapid (<15 min) detection of pathogen nucleic acids without pre-amplification, as well as detection of tumor protein markers in clinical samples. The design provides a facile strategy for enhanced trans cleavage of Cas12a, which accelerates and broadens its applications in biosensing. 相似文献
22.
等压法测定298.15K下LiCl-CaCl2-H2O体系的活度系数 总被引:6,自引:0,他引:6
电解质水溶液热力学性质的研究一直是一个很活跃的研究领域.对含锂水盐体系热力学性质的研究不仅对电解质水溶液理论,而且对盐湖锂资源的开放利用都有非常重要的意义.姚燕等对LiClKClH2O[1],LiClMgCl2H2O[2],LiClMgSO4H2O[3,4],LiClLi2SO4H2O[5]体系多温下热力学性质进行了研究,应用Pitzer电解质水溶液理论模型进行处理,计算出LiCl在不同体系中,很大的浓度范围内的活度系数.但在盐湖卤水中,CaCl2的存在很普遍.对LiClCaCl2混合物在水溶液中的热力学性质研究对理解LiCl在盐… 相似文献
23.
中国散裂中子源(CSNS)加速器真空控制系统负责真空数据采集、设备监控和闸板阀控制与联锁,是设备运行和故障诊断以及超高真空保持的重要保障。本文介绍了加速器真空需求,基于实验物理及工业控制系统EPICS软件框架的真空控制系统设计与实现,使用横河可编程逻辑控制器PLC控制与联锁设备,摩莎MOXA工控机监测真空状态,EPICS PV数据直接进入声音报警系统和历史数据库系统,为工作人员及时发现和处理问题、进行后续数据分析和机器研究等提供了便捷途径和可靠保障。目前,该系统已完成现场安装和调试,并已正式投入运行。运行结果表明,该系统具有稳定性好、可靠性高、人机交互友好的特点,很好地满足了加速器真空控制系统运行的需要。 相似文献
24.
A prey-predator model with Holling II functional response and the carrying capacity of predator depending on its prey 下载免费PDF全文
One prey-predator model is formulated and the global behavior of its solution is analyzed. In this model, the carrying capacity of predator depends on the amount of its prey, and the Holling II functional response is involved. This model may have four classes of positive equilibriums and limit cycle. The positive equilibriums may be stable, or a saddle-node, or a saddle, or a degenerate singular point. In alpine meadow ecosystem, the dynamics of vegetation and plateau pika can be described by this model. Through simulating with virtual parameters, the cause of alpine meadow degradation and effective recovery strategy is investigated. Increasing grazing rate or decreasing plateau pika mortality may cause alpine meadow degradation. Correspondingly, reducing grazing rate and increasing plateau pika mortality may recover the degraded alpine meadow effectively. 相似文献
25.
LI Hongnian XU Yabo BAO Shining LI Haiyang HE Peimo QIAN Haijie LIU Fengqin KUIREXI Yibulaxi 《中国科学A辑(英文版)》2000,43(11)
K3C60 single crystal film was prepared on the cleaved (111) surface of C60 single crystal. Synchrotron radiation angle-resolved photoemission spectra were measured at normal emission with sample temperature at ~150K. Up to four subpeaks of LUMO-derived band were observed. These sub-peaks exhibit distinct energy dispersions which resemble in general the theoretical ones calculated for K3C60 at low temperature with the so-called one-dimensional disordered structure. But there is large deviation of experimental sub-band intervals from the theoretical values. This result is meaningful for the studies of the physical properties of alkali-doped C60 solids, e.g. the mechanism for superconductivity. 相似文献
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Ye T Dong Z Zhao Y Yu J Wang F Zhang L Zou Y 《Dalton transactions (Cambridge, England : 2003)》2011,40(11):2601-2606
Based on the theory of sol-gel science, perovskite SrHfO(3) hollow cuboidal particles with tunable sizes were rationally synthesized by templateless hydrothermal reactions in KOH solutions. The concentrated KOH solution not only elevated the supersaturation of the reactants to promote the grain growth of SrHfO(3) but also controlled the aggregated particle sizes by compressing the electrical double layers of the primary particulates. The following Ostwald ripening process produced hollow particles with sizes ranging from submicrometer to hundred nanometre. The HRTEM image and SAED pattern revealed the single crystal nature of each hollow cuboidal nanoshell. The KOH concentration and reaction time related experiments confirmed that the formation of SrHfO(3) hollow cuboidal nanoshell was driven by the Ostwald ripening process and followed our assumption. The particles experienced solid, core-shell and hollow morphologies as the reaction proceeded. Also, the formation of SrHfO(3) hollow cuboidal nanoshells favored high reaction temperature which initiated and accelerated the ripening process. The as-prepared hollow cuboidal nanoshells displayed blue light emission under UV laser excitation at room temperature. After calcination, the photoluminescence intensity declined due to the improvement of crystallinity. 相似文献
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Ye T Dong Z Zhao Y Yu J Wang F Guo S Zou Y 《Langmuir : the ACS journal of surfaces and colloids》2011,27(14):8878-8884
This paper presents a facile hydrothermal route to synthesize monodispersive and single-crystalline BaHfO(3) hollow micro- and nanospheres in a concentrated basic environment. The hollow spheres were size tunable from submicrometer to nanoscale by simply adjusting the base concentration at a suitable temperature. The base concentration played the key role on forming BaHfO(3) hollow spheres. Detailed investigations on base concentration, reaction temperature, and duration indicated that the formation of BaHfO(3) hollow spheres was driven by Ostwald ripening process. Because of the abundance of defects, the as-prepared BaHfO(3) hollow nanospheres exhibited a blue light emission under UV-light excitation at room temperature. Calcination led to the photoluminescence declination due to the decrease of defects. 相似文献