In this paper, we propose a Fresnel reflection-based optical fiber sensor system for remote refractive index measurement using the optical time domain reflectometry technique as an interrogation method. The surroundin...In this paper, we propose a Fresnel reflection-based optical fiber sensor system for remote refractive index measurement using the optical time domain reflectometry technique as an interrogation method. The surrounding refractive index from a long distance away can be measured easily by using this sensor system, which operates based on testing the Fresnel reflection intensity from the fiber-sample interface. This system is a simple configuration, which is easy to handle. Experimental results showed that the range of this measurement could reach about 100.8km, and the refractive index sensitivities were from 38.71 dB/RIU to 304.89 dB/RIU in the refractive index （RI） range from 1.3486 to 1.4525.展开更多
Major light-harvesting complex of photosystemⅡ(LHCⅡ)plays a dual role in light-harvesting and excited energy dissipation to protect photodamage from excess energy.The regulatory switch is induced by increased acidit...Major light-harvesting complex of photosystemⅡ(LHCⅡ)plays a dual role in light-harvesting and excited energy dissipation to protect photodamage from excess energy.The regulatory switch is induced by increased acidity,temperature or both.However,the molecular origin of the protein dynamics at the atomic level is still unknown.We carried out temperature-jump time-resolved infrared spectroscopy and molecular dynamics simulations to determine the energy quenching dynamics and conformational changes of LHCⅡtrimers.We found that the spontaneous formation of a pair of localα-helices from the 310-helix E/loop and the C-terminal coil of the neighboring monomer,in response to the increased environmental temperature and/or acidity,induces a scissoring motion of transmembrane helices A and B,shifting the conformational equilibrium to a more open state,with an increased angle between the associated carotenoids.The dynamical and allosteric conformation change leads to close contacts between carotenoid lutein 1 and chlorophyll pigment 612,facilitating the fluorescence quenching.Based on these results,we suggest a unified mechanism by which the LHCⅡtrimer controls the dissipation of excess excited energy in response to increased temperature and acidity,as an intrinsic result of intense sun light in plant photosynthesis.展开更多
文摘In this paper, we propose a Fresnel reflection-based optical fiber sensor system for remote refractive index measurement using the optical time domain reflectometry technique as an interrogation method. The surrounding refractive index from a long distance away can be measured easily by using this sensor system, which operates based on testing the Fresnel reflection intensity from the fiber-sample interface. This system is a simple configuration, which is easy to handle. Experimental results showed that the range of this measurement could reach about 100.8km, and the refractive index sensitivities were from 38.71 dB/RIU to 304.89 dB/RIU in the refractive index （RI） range from 1.3486 to 1.4525.
基金supported by the National Natural Science Foundation of China(21433014,11721404,21533003)the Ministry of Science and Technology(2017YFB0203400)+1 种基金Chinese Academy of Sciences Innovation Program(KJCX2-YW-W25)the National Institutes of Health(GM46736,GM64742)。
文摘Major light-harvesting complex of photosystemⅡ(LHCⅡ)plays a dual role in light-harvesting and excited energy dissipation to protect photodamage from excess energy.The regulatory switch is induced by increased acidity,temperature or both.However,the molecular origin of the protein dynamics at the atomic level is still unknown.We carried out temperature-jump time-resolved infrared spectroscopy and molecular dynamics simulations to determine the energy quenching dynamics and conformational changes of LHCⅡtrimers.We found that the spontaneous formation of a pair of localα-helices from the 310-helix E/loop and the C-terminal coil of the neighboring monomer,in response to the increased environmental temperature and/or acidity,induces a scissoring motion of transmembrane helices A and B,shifting the conformational equilibrium to a more open state,with an increased angle between the associated carotenoids.The dynamical and allosteric conformation change leads to close contacts between carotenoid lutein 1 and chlorophyll pigment 612,facilitating the fluorescence quenching.Based on these results,we suggest a unified mechanism by which the LHCⅡtrimer controls the dissipation of excess excited energy in response to increased temperature and acidity,as an intrinsic result of intense sun light in plant photosynthesis.
