The regulator of expression of virion(Rev)protein binds specifically to the Rev-responsive element(RRE)RNA in order to regulate the expression of the human immunodeficiency virus(HIV)-1 genes.Fluorescence indicator di...The regulator of expression of virion(Rev)protein binds specifically to the Rev-responsive element(RRE)RNA in order to regulate the expression of the human immunodeficiency virus(HIV)-1 genes.Fluorescence indicator displacement assays have been used to identify ligands that can inhibit the ReveRRE interaction;however,the small fluorescence indicators cannot fully replace the Rev peptide or protein.As a result,a single rhodamine B labeled Rev(RB-Rev)model peptide was utilized in this study to develop a direct and efficient ReveRRE inhibitor screening model.Due to photon-induced electron transfer quenching of the tryptophan residue on the RB fluorophore,the fluorescence of RB in Rev was weakened and could be dramatically reactivated by interaction with RRE RNA in ammonium acetate buffer(approximately six times).The interaction could reduce the electron transfer between tryptophan and RB,and RRE could also increase RB fluorescence.The inhibitor screening model was evaluated using three known positive ReveRRE inhibitors,namely,proflavin,6-chloro-9-[3-(2-chloroethylamino)propylamino]-2-methoxyacridine(ICR 191),and neomycin,as well as a negative drug,arginine.With the addition of the positive drugs,the fluorescence of the ReveRRE decreased,indicating the displacement of RB-Rev.This was confirmed using atomic force microscopy(AFM)and the fluorescence was essentially unaffected by the addition of arginine.The results demonstrated that RB-Rev can be used as a fluorescent probe for recognizing small ligands that target RRE RNA.The ReveRRE inhibitor screening model offers a novel approach to evaluating and identifying long-acting Rev inhibitors.展开更多
Nano-precision positioning stages are characterized by rigid-flexible coupling systems. The complex dynamic characteristics of mechanical structure of a stage, which are determined by structural and dynamic parameters...Nano-precision positioning stages are characterized by rigid-flexible coupling systems. The complex dynamic characteristics of mechanical structure of a stage, which are determined by structural and dynamic parameters, exert a serious influence on the accuracy of its motion and measurement. Systematic evaluation of such influence is essential for the design and improvement of stages. A systematic approach to modeling the dynamic accuracy of a nano-precision positioning stage is developed in this work by integrating a multi-rigid-body dynamic model of the mechanical system and measurement system models. The influence of structural and dynamic parameters, including aerostatic bearing configurations, motion plane errors, foundation vibrations, and positions of the acting points of driving forces, on dynamic accuracy is investigated by adopting the H-type configured stage as an example. The approach is programmed and integrated into a software framework that supports the dynamic design of nano-precision positioning stages. The software framework is then applied to the design of a nano-precision positioning stage used in a packaging lithography machine.展开更多
Clear,correct imaging is a prerequisite for underwater operations.In real freshwater environment including rivers and lakes,the water bodies are usually turbid and dynamic,which brings extra troubles to quality of ima...Clear,correct imaging is a prerequisite for underwater operations.In real freshwater environment including rivers and lakes,the water bodies are usually turbid and dynamic,which brings extra troubles to quality of imaging due to color deviation and suspended particulate.Most of the existing underwater imaging methods focus on relatively clear underwater environment,it is uncertain that if those methods can work well in turbid and dynamic underwater environments.In this paper,we propose a turbidity-adaptive underwater image enhancement method.To deal with attenuation and scattering of varying degree,the turbidity is detected by the histogram of images.Based on the detection result,different image enhancement strategies are designed to deal with the problem of color deviation and blurring.The proposed method is verified by an underwater image dataset captured in real underwater environment.The result is evaluated by image metrics including structure similarity index measure,underwater color image quality evaluation metric,and speeded-up robust features.Test results exhibit that the method can correct the color deviation and improve the quality of underwater images.展开更多
基金supported by the Natural Science Foundation of Shaanxi Province of China(Grant No.:202012119)the Start-up Funding of Shaanxi University of Science and Technology(Grant No.:2019BJ-48)the Innovation Capability Support Program of Shaanxi Province of China(Grant No.:2021PT-044).
文摘The regulator of expression of virion(Rev)protein binds specifically to the Rev-responsive element(RRE)RNA in order to regulate the expression of the human immunodeficiency virus(HIV)-1 genes.Fluorescence indicator displacement assays have been used to identify ligands that can inhibit the ReveRRE interaction;however,the small fluorescence indicators cannot fully replace the Rev peptide or protein.As a result,a single rhodamine B labeled Rev(RB-Rev)model peptide was utilized in this study to develop a direct and efficient ReveRRE inhibitor screening model.Due to photon-induced electron transfer quenching of the tryptophan residue on the RB fluorophore,the fluorescence of RB in Rev was weakened and could be dramatically reactivated by interaction with RRE RNA in ammonium acetate buffer(approximately six times).The interaction could reduce the electron transfer between tryptophan and RB,and RRE could also increase RB fluorescence.The inhibitor screening model was evaluated using three known positive ReveRRE inhibitors,namely,proflavin,6-chloro-9-[3-(2-chloroethylamino)propylamino]-2-methoxyacridine(ICR 191),and neomycin,as well as a negative drug,arginine.With the addition of the positive drugs,the fluorescence of the ReveRRE decreased,indicating the displacement of RB-Rev.This was confirmed using atomic force microscopy(AFM)and the fluorescence was essentially unaffected by the addition of arginine.The results demonstrated that RB-Rev can be used as a fluorescent probe for recognizing small ligands that target RRE RNA.The ReveRRE inhibitor screening model offers a novel approach to evaluating and identifying long-acting Rev inhibitors.
基金National Science and Technology Major Project of China (Grant Nos. 2009ZX02204- 006 and 2017ZX02101007-002)the National Natural Science Foundation of China (Grant Nos. 51435006 and 51675195).
文摘Nano-precision positioning stages are characterized by rigid-flexible coupling systems. The complex dynamic characteristics of mechanical structure of a stage, which are determined by structural and dynamic parameters, exert a serious influence on the accuracy of its motion and measurement. Systematic evaluation of such influence is essential for the design and improvement of stages. A systematic approach to modeling the dynamic accuracy of a nano-precision positioning stage is developed in this work by integrating a multi-rigid-body dynamic model of the mechanical system and measurement system models. The influence of structural and dynamic parameters, including aerostatic bearing configurations, motion plane errors, foundation vibrations, and positions of the acting points of driving forces, on dynamic accuracy is investigated by adopting the H-type configured stage as an example. The approach is programmed and integrated into a software framework that supports the dynamic design of nano-precision positioning stages. The software framework is then applied to the design of a nano-precision positioning stage used in a packaging lithography machine.
基金This work was supported by the Guangdong Innovative and Entrepreneurial Research Team Program,China(Grant No.2019ZT08Z780)in part by the Dongguan Introduction Program of Leading Innovative and Entrepreneurial Talents,China,in part by the National Key R&D Program of China(Grant No.2017YFC0821200)+1 种基金in part by the Guangdong Basic and Applied Basic Research Foundation,China(Grant No.2021A1515011717)in part by the Space Trusted Computing and Electronic Information Technology Laboratory of BICE,China(Grant No.OBCandETL-2020-06).
文摘Clear,correct imaging is a prerequisite for underwater operations.In real freshwater environment including rivers and lakes,the water bodies are usually turbid and dynamic,which brings extra troubles to quality of imaging due to color deviation and suspended particulate.Most of the existing underwater imaging methods focus on relatively clear underwater environment,it is uncertain that if those methods can work well in turbid and dynamic underwater environments.In this paper,we propose a turbidity-adaptive underwater image enhancement method.To deal with attenuation and scattering of varying degree,the turbidity is detected by the histogram of images.Based on the detection result,different image enhancement strategies are designed to deal with the problem of color deviation and blurring.The proposed method is verified by an underwater image dataset captured in real underwater environment.The result is evaluated by image metrics including structure similarity index measure,underwater color image quality evaluation metric,and speeded-up robust features.Test results exhibit that the method can correct the color deviation and improve the quality of underwater images.