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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]

Cirrus clouds often contain numerous hollow ice crystals, which are distinct in scattering properties from solid ice crystals, and will be challenging to microphysical retrieval and radiative forcing assessment. Currently, hollow ice crystals have not been observed by remote sensing methods, and the estimation of their hollowness is a complex task. To address this issue, the Mixed Modal Hollow Columns (MMHC) model for hollow ice crystals is introduced, and its backscattering properties are computed using the physical optics approximation method. Through comparison with spaceborne lidar observations, we identify a specific type of cirrus associated with the MMHC model for the first time. The visible optical depth of this cirrus is less than or equal to 0.1, and the temperature is between −60 and −40°C. The MMHC characteristic cirrus clouds are prevalent in middle and high latitudes but less comm+on in low latitudes. They exhibit distinct patterns in terms of sea and land distribution as well as seasonal variation. Plain Language Summary: Cirrus clouds typically form at altitudes exceeding 6 km and consist of non‐spherical ice crystals, each with unique optical properties affecting the earth's radiation balance through scattering and absorption. Notably, these crystals include hollow formations, which are distinct in scattering properties from their solid counterparts. The coexistence of hollow and solid ice crystals presents challenges in accurately inverting ice crystal morphology in remote sensing and evaluating radiation properties in climate models. To address these complexities, we propose a MMHC model. Through analysis of spaceborne lidar observational data, we identify characteristic cirrus clouds associated with such type of ice crystals and study the global distribution and seasonal distribution of this kind of cirrus clouds. Key Points: A Mixed Modal Hollow Columns model is formulated to characterize the presence of hollow ice crystals in cirrus cloudsFor the first time, hollow characteristic cirrus clouds are observed using spaceborne lidarHollow characteristic cirrus clouds exhibit distinct global and seasonal distribution variations [ABSTRACT FROM AUTHOR]

Atmospheric water vapor is a crucial factor in the Earth's water cycle. As an important greenhouse gas, changes in the spatio‐temporal distribution of atmospheric water vapor can contribute to the occurrence of various extreme weather phenomena. Lidar, with its high spatial and temporal resolutions, has great potential for applications in water vapor profile detection. Raman lidar and differential absorption lidar (DIAL) have been successfully used to detect atmospheric water vapor. System calibration is crucial to ensure that the measured profile accurately represents the concentration profile of atmospheric water vapor. Choosing an effective system calibration method can ensure the accuracy of long‐term lidar measurements. This paper reviews the latest progress and applications of atmospheric water vapor lidar calibration in recent years. The basic principles of Raman lidar and DIAL calibration are introduced. Various methods and benefits of system calibration are discussed. Raman lidar has three commonly used calibration methods: external calibration, internal calibration, and hybrid calibration methods. The most commonly used method is external calibration based on radiosondes. DIAL is usually implemented with an advantageous self‐calibration method. Finally, potential development directions for atmospheric water vapor lidar and calibration technology are discussed. This article is categorized under:Science of Water > MethodsEngineering Water > MethodsHuman Water > Value of Water [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]

The article proposes a methodology for analyzing the performance of S-lidars (S comes from Scheimpflug) as a new class of environmental remote sensors operating under conditions of wide variability of optical weather and sky background brightness. The novelty of the problem statement, the methods used and the results obtained are determined by their application to laser sensing systems with unconventional design principles and the consequent need to revise the traditional ways of assessing their potential capabilities. The research method is based on a dimensionless-parametric approach, which allows comparing phenomena and systems of different scales and combining complementary characteristics and parameters. Effects of the dimensionless optical weather factor on lidar potential are shown being investigated under various environmental conditions, from the clear atmosphere through haze and mist to fog when probing in Vis/SWIR spectral bands and using Si/InGaAs detector arrays. It is shown exactly how and to what extent the significant differences in their spectral sensitivity and internal noise parameters are susceptible to the wide spectral and energy variability of the sky background brightness observed at very different angles to the Sun. A detailed analysis of the two most important influencing factors within the system, "S-Lidar instrument + Optical weather + External background source", taking into account their wide variability, allowed us to describe their joint nonlinear influence and, thus, to anticipate the imposed limitations. The proposed dimensionless-parametric concept for predicting the potential capabilities of S-lidars with Si/InGaAs arrays is aimed at expanding applications of this rapidly developing class of remote sensors in a wide variety of environments. [ABSTRACT FROM AUTHOR]

In order to conduct more thorough research on the structural characteristics of the atmosphere and the distribution and transmission of atmospheric pollution, the use of remote sensing technology for multi-dimensional detection of the atmosphere is needed. A light-weight, low-volume, low-cost, easy-to-use and low-maintenance mini Infrared Lidar (mIRLidar) sensor is developed for the first time. The model of lidar is established, and the key optical parameters of the mIRLidar are optimized through simulation, in which wavelength of laser, energy of pulse laser, diameter of telescope, field of view (FOV), and bandwidth of filter are included. The volume and weight of the lidar system are effectively reduced through optimizing the structural design and designing a temperature control system to ensure the stable operation of the core components. The mIRLidar system involved a 1064 nm laser (the pulse laser energy 15 μJ, the repetition frequency 5 kHz), a 100 mm aperture telescope (the FOV 1.5 mrad), a 0.5 nm bandwidth of filter and an APD, where the lidar has a volume of 200 mm × 200 mm × 420 mm and weighs about 13.5 kg. It is shown that the lidar can effectively detect three-dimensional distribution and transmission of aerosol and atmospheric pollution within a 5 km detection range, from Horizontal, scanning and navigational atmospheric measurements. It has great potential in the field of meteorological research and environmental monitoring. [ABSTRACT FROM AUTHOR]

Sodium‐ion batteries are regarded as the energy storage of choice for large‐scale applications due to their ample resource and low cost. However, their practical application has been largely retarded by the lack of efficient and stable anodes capable of storing a large amount of Na+ ions reversibly. In this work, we introduce the concept of homojunction into the design of sodium anodes by growing TiO2 nanowires composed of both anatase and bronze intimately interwoven. The interplay between the two phases brings abundant boundaries and interfaces, which drastically increase the storage sites and facilitate the transport of Na+ ions. As a result, it reveals robust Na+ storage, affording a capability of 140 mAh g−1 at a high rate of 20 C and retaining 85 % of the initial capacity after 3000 cycles at 5 C. Furthermore, the practice of TiO2 homojunction has been explored by pairing it with Na3V2(PO4)2O2F cathode, thereby demonstrating the potential of designing homojunction as a promising materials strategy in rechargeable batteries. [ABSTRACT FROM AUTHOR]

The depolarization ratio and backscattering cross sections have been calculated for shapes and size of ice crystals that are typical in cirrus clouds. The calculations are performed in the physical-optics approximation. It is shown that the depolarization ratio approaches some constant when the size of the crystals becomes much larger than the incident wavelength. For the transparent ice crystals, when absorption is absent, the magnitude of this constant strongly depends on crystal shapes. This fact allows inferring the crystal shape from magnitudes of the depolarization ratio in lidar signals. For the lidar wavelengths, where absorption of light is considerable, the depolarization ratio of lidar signals can be used for inferring crystal sizes. Such results are important for the development of algorithms interpreting the signals obtained by both ground-based and space-borne lidars. [ABSTRACT FROM AUTHOR]

Light detection and ranging (LIDAR) is an active remote sensing system. Lidar echo signal is non-linear and non-stationary, which is often accompanied by various noises. In order to filter out the noise and extract valid signal information, a suitable method should be chosen for noise reduction. Some denoising methods are commonly used, such as the wavelet transform (WT), the empirical mode decomposition (EMD), the variational mode decomposition (VMD), and their improved algorithms. In this paper, a new denoising method named the WT-VMD joint algorithm based on the sparrow search algorithm (SSA), for lidar signal is selected by comparative experiment analysis. It is shown that this method is the most suitable one with the maximum signal-to-noise ratio (SNR), the minimum root-mean-square error (RMSE), and a relatively small indicator of smoothness when it is used in three kinds (50, 100, and 1000 pulses) of simulate lidar signals. The SNR is increased by 138.5%, 77.8% and 42.8% and the RMSE is decreased by 81.8%, 72.0% and 68.8% when being used to the three kinds of cumulative signal without pollution. Then, the SNR is increased by 83.3%, 60.4% and 24.0% and the RMSE is decreased by 70.8%, 66.0% and 50.5% when being used to the three kinds of cumulative signal with aerosol and clouds. The WT-VMD joint algorithm based on SSA is used in the denoising process for the actual lidar signal, showing extraordinary denoising effect and will improve the inversion accuracy of the lidar signal. [ABSTRACT FROM AUTHOR]

On 15 March 2021, the strongest sandstorm of the last 10 years occurred in China. The MODIS, MPL lidar, EDM 180, ADI 2080 and Meteorological observation instruments were used to observe the dust in Jinan, China, while the HYSPLIT model was also employed to find the source. It was found that the dust originated from Mongolia and the Gobi desert and was transported to Jinan at night on 14th March, lasting until the 18th. Multi-layer dust was observed, of which the dust below the height of 1 km was strongest with the VDR about 0.2 and the maximum extinction coefficient up to 3 km−1. The values of AOD and AE were greater than 2 and less than 0.25, respectively. The mass concentrations of PM10 and PM2.5 increased rapidly, and were up to 573 µg/m3 and 3406 µg/m3, respectively. Additionally, the mass concentration ratio decreased rapidly, with a minimum of 17%. The particle size of the dust was mainly distributed between 0.58–6.50 micros due to larger particles increasing dramatically; simultaneously, both the proportion and the value for calcium ions in PM2.5 went up. The dust had an obvious impact on the vertical structure of the air temperature, resulting in occurrence of a strong inversion layer. [ABSTRACT FROM AUTHOR]

All elements of the scattering matrix have been numerically studied for particles of irregular shapes whose size is much larger than incident wavelength. The calculations are performed in the physical optics approximation for a particle size of 20 μm at a wavelength of 0.532 μm. Here the scattered intensity reveals the backscattering coherent peak. It is shown that the polarization elements of the matrix reveal the surges within the backscattering peak. The angular width of the surges does not practically depend on particle shape, but depends on the particle size. It is shown that these surges are created by interference between the conjugate scattered waves propagating in the inverse directions. The results obtained are of interest for interpretation of lidar measurements in cirrus clouds. [ABSTRACT FROM AUTHOR]

AZ91‐0.9Ce alloy with a thickness of 8 mm is prepared by die casting. The formation process of main compounds in the alloy, the role of main compounds in fracture process, the main crack source, and crack propagation path of the alloy are studied. Results show that AZ91‐0.9Ce alloy is mainly composed of α‐Mg matrix, Mg17Al12 compound, Al4Ce compound, and a small amount of Al–Mn–Ce ternary compound. Among them, Al4Ce is formed prior to the Mg17Al12 compound. Mg17Al12 is formed by eutectic reaction, and Al–Mn–Ce ternary compound is formed at a later stage of solidification. Mg17Al12 and Al4Ce are the main crack sources of the alloy during the fracture process. Crack locations in the alloy mainly include grain boundaries, phase boundaries, and Mg17Al12 and Al4Ce compounds. The fracture mechanism of the alloy is that with the increase of load cracks occur at Mg17Al12 and Al4Ce compounds and connect with each other through intergranular and a small amount of transgranular to form the main crack. With the load continues to increase, the main crack gradually expands until alloy fracture failure. The continuous network distribution along grain boundaries of the Mg17Al12 compound is an important reason for intergranular fracture. [ABSTRACT FROM AUTHOR]

Metals such as Sb and Bi are important anode materials for sodium‐ion batteries because they feature a large capacity and low reaction potential. However, the accumulation of stress and strain upon sodium storage leads to the formation of cracks and fractures, resulting in electrode failure upon extended cycling. In this work, the design and construction of BixSb1−x bimetallic alloy films with a compositional gradient to mitigate the intrinsic structural instability is reported. In the gradient film, the top is rich in Sb, contributing to the capacity, while the bottom is rich in Bi, helping to reduce the stress in the interphase between the film and the substrate. Significantly, this gradient film affords a high reversible capacity of ≈500 mAh g−1 and sustains 82% of the initial capacity after 1000 cycles at 2 C, drastically outperforming the solid‐solution counterpart and many recently reported alloy anodes. Such a gradient design can open up the possibilities to engineering high‐capacity anode materials that are structurally unstable due to the huge volume variation upon energy storage. [ABSTRACT FROM AUTHOR]