微型仿生机器人是一种仿照生物外形和运动形态制作设计的机器人,凭借其体型小、机动性高、环境适应性强等优点,在复杂环境探索、敌情侦察等特殊场景中具有较高的应用前景,近年来备受研究人员的关注.但是微型机器人运动稳定性弱、单目相...微型仿生机器人是一种仿照生物外形和运动形态制作设计的机器人,凭借其体型小、机动性高、环境适应性强等优点,在复杂环境探索、敌情侦察等特殊场景中具有较高的应用前景,近年来备受研究人员的关注.但是微型机器人运动稳定性弱、单目相机环境感知精度低等问题的存在一直制约着其实际应用.本文仿照昆虫“独角仙”设计了一种新的微型仿生爬虫机器人,开发了基于生物运动调控机制的六足机器人控制系统,改进了基于啮齿类动物空间导航原理的同时定位与建图系统.使用自研的微型仿生爬虫机器人在人造沙盘和真实室内走廊两个场景中进行了实验验证.在人造沙盘场景,由于微型仿生爬虫机器人提供的环境图像质量模糊,ORB-SLAM3算法无法完成回环检测,不能正确识别曾经见过的场景.类脑同步定位与地图构建(simultaneous localization and mapping,SLAM)系统回环准确率高达100%,比原RatSLAM算法提高了4.36%.在真实室内走廊场景,ORB-SLAM3算法和RatSLAM算法建图效果都比较差,而类脑SLAM不仅有着较好的建图结果,而且在准确率100%的同时召回率也高达97.87%.与ORB-SLAM3和RatSLAM算法相比,类脑SLAM系统取得了较好的建图结果.因此,自研的微型仿生爬虫机器人具有灵活的运动能力、鲁棒的导航定位能力,促使微型仿生机器人离实际应用更近了一步.展开更多
The fundamental unit of rapid, physiological color change in vertebrates is the dermal chromato- phore unit. This unit, comprised of cellular associations between different chromatophore types, is relatively conserved...The fundamental unit of rapid, physiological color change in vertebrates is the dermal chromato- phore unit. This unit, comprised of cellular associations between different chromatophore types, is relatively conserved across the fish, amphibian, and reptilian species capable of physiological color change and numerous attempts have been made to understand the nature of the four major chro- matophore types （melanophores, erythrophores, xanthophores, and iridophores） and their bio- chemical regulation. In this review, we attempt to describe the current state of knowledge regard- ing what classifies a pigment cell as a dynamic chromatophore, the unique characteristics of each chromatophore type, and how different hormones, neurotransmitters, or other signals direct pig- ment reorganization in a variety of vertebrate taxa.展开更多
Neomycins are a group of aminoglycoside antibiotics with both clinical and agricultural applications.To elucidate the regulatory mechanism of neomycin biosynthesis,we completed draft genome sequencing of a neomycin pr...Neomycins are a group of aminoglycoside antibiotics with both clinical and agricultural applications.To elucidate the regulatory mechanism of neomycin biosynthesis,we completed draft genome sequencing of a neomycin producer Streptomyces fradiae CGMCC 4.7387 from marine sediments,and the neomycin biosynthesis gene cluster was identified.Inactivation of the afsA-g gene encoding a γ-butyrolactone(GBL) synthase in S.fradiae CGMCC 4.7387 resulted in a significant decrease of neomycin production.Quantitative RT-PCR analysis revealed that the transcriptional level of neoR and the aphA-neoGH operon were reduced in the afsA-g::aac(3)Ⅳ mutant.Interestingly,a conserved binding site of AdpA,a key activator in the GBL regulatory cascade,was discovered upstream of neoR,a putative regulatory gene encoding a protein with an ATPase domain and a tetratricopeptide repeat domain.When neoR was inactivated,the neomycin production was reduced about 40%in comparison with the WT strain.Quantitative RT-PCR analysis revealed that the transcriptional levels of genes in the aphA-neoGH operon were reduced clearly in the neoR::aac(3)Ⅳ mutant.Finally,the titers of neomycin were improved considerably by overexpression of qfsA-gand neoR in S.fradiae CGMCC 4.7387.展开更多
文摘微型仿生机器人是一种仿照生物外形和运动形态制作设计的机器人,凭借其体型小、机动性高、环境适应性强等优点,在复杂环境探索、敌情侦察等特殊场景中具有较高的应用前景,近年来备受研究人员的关注.但是微型机器人运动稳定性弱、单目相机环境感知精度低等问题的存在一直制约着其实际应用.本文仿照昆虫“独角仙”设计了一种新的微型仿生爬虫机器人,开发了基于生物运动调控机制的六足机器人控制系统,改进了基于啮齿类动物空间导航原理的同时定位与建图系统.使用自研的微型仿生爬虫机器人在人造沙盘和真实室内走廊两个场景中进行了实验验证.在人造沙盘场景,由于微型仿生爬虫机器人提供的环境图像质量模糊,ORB-SLAM3算法无法完成回环检测,不能正确识别曾经见过的场景.类脑同步定位与地图构建(simultaneous localization and mapping,SLAM)系统回环准确率高达100%,比原RatSLAM算法提高了4.36%.在真实室内走廊场景,ORB-SLAM3算法和RatSLAM算法建图效果都比较差,而类脑SLAM不仅有着较好的建图结果,而且在准确率100%的同时召回率也高达97.87%.与ORB-SLAM3和RatSLAM算法相比,类脑SLAM系统取得了较好的建图结果.因此,自研的微型仿生爬虫机器人具有灵活的运动能力、鲁棒的导航定位能力,促使微型仿生机器人离实际应用更近了一步.
文摘The fundamental unit of rapid, physiological color change in vertebrates is the dermal chromato- phore unit. This unit, comprised of cellular associations between different chromatophore types, is relatively conserved across the fish, amphibian, and reptilian species capable of physiological color change and numerous attempts have been made to understand the nature of the four major chro- matophore types （melanophores, erythrophores, xanthophores, and iridophores） and their bio- chemical regulation. In this review, we attempt to describe the current state of knowledge regard- ing what classifies a pigment cell as a dynamic chromatophore, the unique characteristics of each chromatophore type, and how different hormones, neurotransmitters, or other signals direct pig- ment reorganization in a variety of vertebrate taxa.
基金funded in part by the Ministry of Science and Technology of China(2015CB150600)the National Natural Science Foundation of China(31370095 and 31522001)
文摘Neomycins are a group of aminoglycoside antibiotics with both clinical and agricultural applications.To elucidate the regulatory mechanism of neomycin biosynthesis,we completed draft genome sequencing of a neomycin producer Streptomyces fradiae CGMCC 4.7387 from marine sediments,and the neomycin biosynthesis gene cluster was identified.Inactivation of the afsA-g gene encoding a γ-butyrolactone(GBL) synthase in S.fradiae CGMCC 4.7387 resulted in a significant decrease of neomycin production.Quantitative RT-PCR analysis revealed that the transcriptional level of neoR and the aphA-neoGH operon were reduced in the afsA-g::aac(3)Ⅳ mutant.Interestingly,a conserved binding site of AdpA,a key activator in the GBL regulatory cascade,was discovered upstream of neoR,a putative regulatory gene encoding a protein with an ATPase domain and a tetratricopeptide repeat domain.When neoR was inactivated,the neomycin production was reduced about 40%in comparison with the WT strain.Quantitative RT-PCR analysis revealed that the transcriptional levels of genes in the aphA-neoGH operon were reduced clearly in the neoR::aac(3)Ⅳ mutant.Finally,the titers of neomycin were improved considerably by overexpression of qfsA-gand neoR in S.fradiae CGMCC 4.7387.
