Search

Transmembrane delivery of biologically active nucleic acids is an important process in cells and has inspired one to develop advanced drug delivery techniques. In this contribution, molecular‐level single‐stranded nucleic acid transmembrane carriers are reported based on 3.2 nm long Huc's foldamers (AOrnQ3Q3)8 and (mQ3Q2)8 with linearly and helically aligned positive charges, respectively. These two foldamers not only show very strong DNA affinity via electrostatic interactions but also discriminatively bind single‐stranded DNA (ss‐DNA) and double‐stranded DNA (ds‐DNA), corroborating the importance of precise charge arrangement in the electrostatic interactions. More importantly, these two foldamers are capable of efficiently transporting ss‐DNA across the lipid membranes, and the ss‐DNA transport activity of (AOrnQ3Q3)8 with linearly aligned charges is higher than that of (mQ3Q2)8 with helically aligned charges. Thus a type of novel single‐stranded nucleic acid transmembrane molecular carriers based on positively charged helical foldamers are introduced. Further, effective and enhanced expression in EGFP‐mRNA transfection experiments strongly demonstrates the potential of positively charged foldamers for RNA transmembrane transport and therapy. [ABSTRACT FROM AUTHOR]

During 14–16 March 2021, a large-scale dust storm event occurred in the northern region of China, and it was considered the most intense event in the past decade. This study employs observation data for PM2.5 and PM10 from the air quality monitoring station, the HYSPLIT model, ground-based polarized Lidar networks, AGRI payload data from Fengyun satellites and CALIPSO satellite Lidar data to jointly explore and scrutinize the three-dimensional spatial and temporal characteristics of aerosol transport. Firstly, by integrating meteorological data for PM2.5 and PM10, the air quality is assessed across six stations within the Lidar network during the dust storm. Secondly, employing a backward trajectory tracking model, the study elucidates sources of dust at the Lidar network sites. Thirdly, deploying a newly devised portable infrared 1064 nm Lidar and a pulsed 532 nm Lidar, a ground-based Lidar observation network is established for vertical probing of transboundary dust transport within the observed region. Finally, by incorporating cloud imagery from Fengyun satellites and CALIPSO satellite Lidar data, this study revealed the classification of dust and the height distribution of dust layers at pertinent sites within the Lidar observation network. The findings affirm that the eastward movement and southward compression of the intensifying Mongolian cyclone led to severe dust storm weather in western and southern Mongolia, as well as Inner Mongolia, further transporting dust into northern, northwestern, and northeastern parts of China. This dust event wielded a substantial impact on a broad expanse in northern China, manifesting in localized dust storms in Inner Mongolia, Beijing, Gansu, and surrounding areas. In essence, the dust emanated from the deserts in Mongolia and northwest China, encompassing both deserts and the Gobi region. The amalgamation of ground-based and spaceborne Lidar observations conclusively establishes that the distribution height of dust in the source region ranged from 3 to 5 km. Influenced by high-pressure systems, the protracted transport of dust over extensive distances prompted a gradual reduction in its distribution height owing to sedimentation. The comprehensive analysis of pertinent research data and information collectively affirms the precision and efficacy of the three-dimensional aerosol monitoring conducted by the ground-based Lidar network within the region. [ABSTRACT FROM AUTHOR]

This paper presents a method for instantaneous measurement of Fabry-Parot(F-P) transmittance curve. Compared with the previous method, this method has many advantages, such as scanning-free, simple in structure and accuracy.

The side-scattering lidar based on the CCD camera is a powerful tool to measure the near- ground aerosol, which is most interesting for the environmental and meteorological departments. The inversion method for the side-scattering lidar is different from the conventional Fernald method due to the differences in two lidar equations. A new inversion method for the side-scattering lidar to retrieve the aerosol backscattering coefficient is proposed for the first time, which is based on the aerosol backscattering coefficient at the ground as a restriction condition. Numerical simulation is used to analyze the convergence of this new method. Case studies indicate that this new method is reasonable and feasible.REFERENCES

Water Aerosol Raman Lidar-II is an active detection instrument with high temporal and spatial resolution at Nanjiao observation station, and that could continuous water vapor mixing ratio (WVMR) measurements. WVMR profiles inversion from lidar data and water ratio retrieved from radiosonde data are in good agreement. The statistical results of the vertical distribution of WVMR indicate that WVMR seasonal mean distribution is consistent with precipitation. In addition, WVMR in Nanjiao station is related to total cloud cover.

The Polarization Lidar has been developed for cirrus cloud optical properties measurement. The Nd-YAG laser is employed as emitting linear source and two channels are used for detecting back-scattering signals from cirrus cloud including two 532 nm Orthogonal Polarization channels. Measurements were carried out from December 2010, to February 2013. In this work, we consider the only linear depolarization ratio measured at a wavelength of 532 nm. The dependences of depolarization ratios on both the size of ice crystals and the distribution of their distortion angles were also calculated. These results were compared with each other and used for retrieving the microphysical parameters of cirrus clouds observed in Hefei.

Lidar technologies are widely used for retrieving microphysics of cirrus clouds, i.e. sizes, shapes and spatial orientation of ice crystals constituting the clouds. Interpretation of the lidar signals are based on the backscattered light. However, properties of the light backscattered by the ice crystals have not been well known and understood yet. The reason of this is that the problem of light scattering by the ice crystals much larger that incident wavelengths has not been solved satisfactorily yet because of great demands to computer resources. In this contribution we review the physical optics approximation as a prospective method to solve the light scattering problem on large nonspherical particles in lidar application.

The light scattering matrix is calculated for large dust particles with irregular shape and refractive index of 1.3116+i0.0. The scattering matrix in the backward direction needed for lidar studies is separately discussed. In this case, the obtained results for the lidar and depolarization ratios are in good agreement with experimental data. It is shown that for randomly oriented particles the number of particle orientations needed for numerical calculations by exact methods like DDA becomes a crucial parameter. In particular, for particles with size parameters larger than 40 the number of orientations should be more than 1000.

In recent years, the applications of lidars for remote sensing of the environment have been expanding and deepening. Among them, continuous-wave (CW) range-resolved (RR) S-lidars (S comes from Scheimpflug) have proven to be a new and promising class of non-contact and non-perturbing laser sensors. They use low-power CW diode lasers, an unconventional depth-of-field extension technique and the latest advances in nanophotonic technologies to realize compact and cost-effective remote sensors. The purpose of this paper is to propose a generalized methodology to justify the selection of a set of non-energetic S-lidar parameters for a wide range of applications and distance scales, from a bench-top test bed to a 10-km path. To set the desired far and near borders of operating range by adjusting the optical transceiver, it was shown how to properly select the lens plane and image plane tilt angles, as well as the focal length, the lidar base, etc. For a generalized analysis of characteristic relations between S-lidar parameters, we introduced several dimensionless factors and criteria applicable to different range scales, including an S-lidar-specific magnification factor, angular function, dynamic range, "one and a half" condition, range-domain quality factor, etc. It made possible to show how to reasonably select named and dependent non-energetic parameters, adapting them to specific applications. Finally, we turned to the synthesis task by demonstrating ways to achieve a compromise between a wide dynamic range and high range resolution requirements. The results of the conducted analysis and synthesis allow increasing the validity of design solutions for further promotion of S-lidars for environmental remote sensing and their better adaptation to a broad spectrum of specific applications and range scales. [ABSTRACT FROM AUTHOR]

Ozone near the surface of the atmosphere directly stimulates the human respiratory tract and affects human health. In recent years, ozone pollution in China has become a serious problem, so controlling ozone pollution is an urgent task. Differential absorption lidar is a useful tool for detecting ozone concentration, but it cannot receive complete signals in the lower hundreds of meters because of the overlap factor. CCD imaging lidar technology can effectively solve this problem. A fitting method of inverting the ozone concentration profile using ultraviolet differential CCD imaging lidar is proposed in this paper. The effect of three different types of aerosol extinction coefficient, three different types of ozone concentration, and five different types of aerosol wavelength index on retrieving ozone concentrations was analyzed using simulation. For clean aerosol, the relative error of the retrieved ozone concentration is less than 5%. As to polluted aerosol, the relative error of the retrieved ozone concentration is less than 10%. As to heavily polluted aerosol, the relative error of the retrieved ozone concentration is less than 25%. The results show that the larger the value of the aerosol extinction coefficient, the larger the relative error of the retrieved ozone concentration; meanwhile, the lower the ozone concentration, the larger the relative error of the retrieved ozone concentration; at the same time, the further the aerosol wavelength index deviates from 1, the larger the relative error of the retrieved ozone concentration. The relative error of the retrieved ozone concentration in this case was about 4%. It is shown that this fitting method of retrieving ozone concentrations is reasonable and feasible. [ABSTRACT FROM AUTHOR]

A movable multi-wavelength Raman lidar (TMPRL) was built in Hefei, China. Emitting with three wavelengths at 1064, 532, and 355nm, receiving three above Mie scattering signals and two nitrogen Raman signals at 386 and 607nm, and depolarization signal at 532nm, TMPRL has the capacity to investigate the height resolved optical and microphysical properties of aerosol and cloud. The retrieval algorithms of optical parameters base on Mie-Raman technique and the microphysical parameters based on Bayesian optimization method were also developed and applied to observed lidar data. Designing to make unattended operation and 24/7 continuous working, TMPRL has joined several field campaigns to study on the aerosol, cloud and their interaction researches. Some observed results of aerosol and cloud optical properties and the first attempt to validate the vertical aerosol size distribution retrieved by TMPRL and in-situ measurement by airplane are presented and discussed.

The interaction relationship between cloud and aerosol is studied via their optical depth and cloud effective radius based on ground-based remote sensors. By attenuated backscatter obtained by lidar the optical depth of cloud and aerosol is retrieved. Combing with liquid water path observed by microwave radiometer, the cloud number concentration and cloud effective radius is also retrieved based on the adiabatic hypothesis Cases studies shows that during the stable stratocumulus with interval precipitation period and aerosol with vertical motion, the cloud effective radius shows both negative and positive relationship with aerosol optical depth. It may be due to the difference of liquid water path of the cloud properties and shows complex interaction with aerosol.

In theory, lidar overlap factor can be derived from the difference between the particle backscatter coefficient retrieved from lidar elastic signal without overlap correction and the actual particle backscatter coefficient, which can be obtained by other measured techniques. The side-scatter signal using a CCD camera is testified to be a powerful tool to detect the particle backscatter coefficient in near ground layer during night time. In experiment, by combining side-scatter and backscatter signals the geometric form factor for vertically-pointing Mie lidar in 532 nm channel is determined successfully, which is corrected by an iteration algorithm combining the retrieved particle backscatter coefficient using CCD sidescatter method and Fernald method. In this study, the method will be expanded to 1064 nm channel in dual-wavelength Mie lidar during routine campaigns. The experimental results in different atmosphere conditions demonstrated that the method present in this study is available in practice.