Comparison of the emission wavelengths by a single fluorescent dye on in vivo 3-photon imaging of mouse brains

Multiphoton microscopy(MPM)is a powerful imaging technology for brain research.The imaging depth in MPM is partly determined by emission wavelength of fluorescent labels.It has been demonstrated that a longer emission wavelength is favorable for signal detection as imaging depth increases.However,there has been no comparison with near-infrared(NIR)emission.In order to quantitatively analyze the effect of emission wavelength on 3-photon imaging of mouse brains in vivo,we utilize the same excitation wavelength to excite a single fluorescent dye and simultaneously collect NIR and orange-red emission fluorescence at 828 nm and 620 nm,respectively.Both experimental and simulation results show that as the imaging depth increases,NIR emission decays less than orange-red fluorescent emission.These results show that it is preferable to shift the emission wavelength to NIR to enable more e±cient signal collection deep in the brain.

Influence of non-uniform electric field distribution on the atmospheric pressure air dielectric barrier discharge

The dielectric barrier discharge(DBD)in air at atmospheric pressure is not suitable for industrial applications due to its randomly distributed discharge filaments.In this paper,the influence of the electric field distribution on the uniformity of DBD is theoretically analyzed and experimentally verified.It is found that a certain degree of uneven electric field distributions can control the development of electron avalanches and regulate their transition to streamers in the gap.The discharge phenomena and electrical characteristics prove that an enhanced Townsend discharge can be formed in atmospheric-pressure air with a curved-plate electrode.The spectral analysis further confirms that the gas temperature of the plasma produced by the curved-plate electrode is close to room temperature,which is beneficial for industrial applications.This paper presents the relationship between the electron avalanche transition and the formation of a uniform DBD,which can provide some references for the development and applications of the DBD in the future.

Aberration correction for multiphoton microscopy using covariance matrix adaptation evolution strategy

Multiphoton microscopy is the enabling tool for biomedical research,but the aberrations of biological tissues have limited its imaging performance.Adaptive optics(AO)has been developed to partially overcome aberration to restore imaging performance.For indirect AO,algorithm is the key to its successful implementation.Here,based on the fact that indirect AO has an analogy to the black-box optimization problem,we successfully apply the covariance matrix adaptation evolution strategy(CMA-ES)used in the latter,to indirect AO in multiphoton microscopy(MPM).Compared with the traditional genetic algorithm(GA),our algorithm has a greater improvement in convergence speed and convergence accuracy,which provides the possibility of realizing real-time dynamic aberration correction for deep in vivo biological tissues.