The spectroscopic methods for the ultrafast electronic and structural dynamics of materials require fully coherent extreme ultraviolet and soft X-ray radiation with high-average brightness.Seeded free-electron lasers(...The spectroscopic methods for the ultrafast electronic and structural dynamics of materials require fully coherent extreme ultraviolet and soft X-ray radiation with high-average brightness.Seeded free-electron lasers(FELs)are ideal sources for delivering fully coherent soft X-ray pulses.However,due to state-of-theart laser system limitations,it is challenging to meet the ultraviolet seed laser’s requirements of sufficient energy modulation and high repetition rates simultaneously.The self-modulation scheme has been proposed and recently demonstrated in a seeded FEL to relax the seed laser requirements.Using numerical simulations,we show that the required seed laser intensity in the self-modulation is~3 orders of magnitude lower than that in the standard high-gain harmonic generation(HGHG).The harmonic self-modulation can launch a singlestage HGHG FEL lasing at the 30th harmonic of the seed laser.Moreover,the proof-of-principle experimental results confirm that the harmonic self-modulation can still amplify the laser-induced energy modulation.These achievements reveal that the self-modulation can not only remarkably reduce the requirements of the seed laser but also improve the harmonic upconversion efficiency,which paves the way for realizing high-repetitionrate and fully coherent soft X-ray FELs.展开更多
The efficacious delivery of antimicrobial drugs to intractable oral biofilms remains a challenge due to inadequate biofilm penetration and lack of pathogen targeting.Herein,we have developed a microenvironment-activat...The efficacious delivery of antimicrobial drugs to intractable oral biofilms remains a challenge due to inadequate biofilm penetration and lack of pathogen targeting.Herein,we have developed a microenvironment-activated poly(ethylene glycol)(PEG)-sheddable nanoplatform to mediate targeted delivery of drugs into oral biofilms for the efficient prevention of dental caries.The PEGylated nanoplatform with enhanced biofilm penetration is capable of deshielding the PEG layer under slightly acidic conditions in a PEG chain length-dependent manner to re-expose the bacteria-targeting ligands,thereby facilitating targeted codelivery of ciprofloxacin(CIP)and IR780 to the bacteria after accumulation within biofilms.The nanoplatform tends to induce bacterial agglomeration and suffers from degradation in the acidic oral biofilm microenvironment,triggering rapid drug release on demand around bacterial cells.The self-modulating nanoplatform under near-infrared(NIR)irradiation accordingly displays greatly augmented potency in oral biofilm penetration and disruption compared with drugs alone.Topical oral treatment with nanoplatforms involving synergetic pharmacological and photothermal/photodynamic trinary therapy results in robust biofilm dispersion and efficacious suppression of severe tooth decay in rats.This versatile nanoplatform can promote local accumulation and specific drug transport into biofilms and represents a new paradigm for targeted drug delivery for the management of oral biofilm-associated infections.展开更多
We demonstrated experimentally the formation of monoenergetic beams of accelerated electrons by focusing femtosecond laser radiation with an intensity of 2×1017W/cm2onto the edge of an aluminum foil.The electrons...We demonstrated experimentally the formation of monoenergetic beams of accelerated electrons by focusing femtosecond laser radiation with an intensity of 2×1017W/cm2onto the edge of an aluminum foil.The electrons had energy distributions peaking in the 0.2–0.8 MeV range with energy spread less than 20%.The acceleration mechanism related to the generation of a plasma wave as a result of self-modulation instability of a laser pulse in a dense plasma formed by a prepulse(arriving 12 ns before the main pulse)is considered.One-dimensional and two-dimensional Particle in Cell(PIC)simulations of the laser–plasma interaction showed that effective excitation of a plasma wave as well as trapping and acceleration of an electron beam with an energy on the order of 1 MeV may occur in the presence of sharp gradients in plasma density and in the temporal shape of the pulse.展开更多
基金supported by the CAS Project for Young Scientists in Basic Research(Grant No.YSBR042)the National Natural Science Foundation of China(Grant Nos.12125508 and 11935020)+1 种基金the Program of Shanghai Academic/Technology Research Leader(Grant No.21XD1404100)the Shanghai Pilot Program for Basic Research of the Chinese Academy of Sciences,Shanghai Branch(Grant No.JCYJ-SHFY-2021-010).
文摘The spectroscopic methods for the ultrafast electronic and structural dynamics of materials require fully coherent extreme ultraviolet and soft X-ray radiation with high-average brightness.Seeded free-electron lasers(FELs)are ideal sources for delivering fully coherent soft X-ray pulses.However,due to state-of-theart laser system limitations,it is challenging to meet the ultraviolet seed laser’s requirements of sufficient energy modulation and high repetition rates simultaneously.The self-modulation scheme has been proposed and recently demonstrated in a seeded FEL to relax the seed laser requirements.Using numerical simulations,we show that the required seed laser intensity in the self-modulation is~3 orders of magnitude lower than that in the standard high-gain harmonic generation(HGHG).The harmonic self-modulation can launch a singlestage HGHG FEL lasing at the 30th harmonic of the seed laser.Moreover,the proof-of-principle experimental results confirm that the harmonic self-modulation can still amplify the laser-induced energy modulation.These achievements reveal that the self-modulation can not only remarkably reduce the requirements of the seed laser but also improve the harmonic upconversion efficiency,which paves the way for realizing high-repetitionrate and fully coherent soft X-ray FELs.
基金This work was supported by National Natural Science Foundation of China(Grant No.21975133,21774062)the Key Projects of Natural Science Foundation of Tianjin,China(19JCZDJC36900)This work is dedicated to the 100th anniversary of Chemistry at Nankai University.
文摘The efficacious delivery of antimicrobial drugs to intractable oral biofilms remains a challenge due to inadequate biofilm penetration and lack of pathogen targeting.Herein,we have developed a microenvironment-activated poly(ethylene glycol)(PEG)-sheddable nanoplatform to mediate targeted delivery of drugs into oral biofilms for the efficient prevention of dental caries.The PEGylated nanoplatform with enhanced biofilm penetration is capable of deshielding the PEG layer under slightly acidic conditions in a PEG chain length-dependent manner to re-expose the bacteria-targeting ligands,thereby facilitating targeted codelivery of ciprofloxacin(CIP)and IR780 to the bacteria after accumulation within biofilms.The nanoplatform tends to induce bacterial agglomeration and suffers from degradation in the acidic oral biofilm microenvironment,triggering rapid drug release on demand around bacterial cells.The self-modulating nanoplatform under near-infrared(NIR)irradiation accordingly displays greatly augmented potency in oral biofilm penetration and disruption compared with drugs alone.Topical oral treatment with nanoplatforms involving synergetic pharmacological and photothermal/photodynamic trinary therapy results in robust biofilm dispersion and efficacious suppression of severe tooth decay in rats.This versatile nanoplatform can promote local accumulation and specific drug transport into biofilms and represents a new paradigm for targeted drug delivery for the management of oral biofilm-associated infections.
基金supported by the programme ‘Extreme Light Fields and Their Applications’ of the Presidium of the Russian Academy of Sciences
文摘We demonstrated experimentally the formation of monoenergetic beams of accelerated electrons by focusing femtosecond laser radiation with an intensity of 2×1017W/cm2onto the edge of an aluminum foil.The electrons had energy distributions peaking in the 0.2–0.8 MeV range with energy spread less than 20%.The acceleration mechanism related to the generation of a plasma wave as a result of self-modulation instability of a laser pulse in a dense plasma formed by a prepulse(arriving 12 ns before the main pulse)is considered.One-dimensional and two-dimensional Particle in Cell(PIC)simulations of the laser–plasma interaction showed that effective excitation of a plasma wave as well as trapping and acceleration of an electron beam with an energy on the order of 1 MeV may occur in the presence of sharp gradients in plasma density and in the temporal shape of the pulse.
