Morphological Profiles of Sand Dunes from ICESat-2 Geolocated Photons

Aeolian process leads to the transportation and accumulation of sand particles that result in sand dune landforms. The structure and shape of the sand dunes are driven by the parameters of interacting wind force and the material composition of sand within. Cross-section profiles over the sand dunes will essay the geomorphological parameters through which the steady state and rate of sand transport can be computed. National Aeronautics and Space Administration’s novel satellite namely Ice, Cloud and land Elevation Satellite-2 (ICESat-2) hosts a solo sensor namely Advanced Topographic Laser Altimeter System (ATLAS) which is a photon counting instrument that measures the round-trip time of the light pulse being emitted and reflected back from the surface determines the true height of the topographic feature on the Earth. In this article, cross-section profiles generated from the beams of ICESat-2 ground-tracks acquired over sand dunes of the Thar Desert region were analysed for detecting the geomorphological parameters. Observations from the cross-section profiles have resulted in giving unprecedented details about the shapes and morphological settings of various types of sand dunes like barchanoids, parabolic, longitudinal, and transverse dunes. Morphological parameters of sand dunes like the length of the stoss slope, crest height, slip face details, inter-arms spacing, height of the trailing arms, length of the depositional lobes, and sinuosity of the recurring crest lines were retrieved with ease from the Level-2A data product namely ATL03 of ICESat-2/ATLAS.

Near-stoichiometric Ti:LiNbO3 strip waveguide with varied substrate refractive index in waveguide layer

We report the near-stoichiometric Ti：LiNbO3 strip waveguides fabricated by vapour transport equilibration （VTE） at 1060~^{／circ}C for 12 h and co-diffusion of 4--8~／mu m wide, 115-nm thick Ti-strips. Optical studies show that these waveguides are monomode at 1.5~／mu m and have losses of 1.3 and 1.1~dB/cm for the TM and TE modes, respectively. In the waveguide width/depth direction, the mode field follows a Gauss/Hermite--Gauss profile. A secondary ion mass spectrometry study reveals that the Ti profile follows a sum of two error functions along the width direction and a complementary error function in the depth direction. Micro-Raman analysis shows that the Li-composition in the depth direction also follows a complementary error function. The mean Li/Nb ratio in the waveguide layer is about 0.98. The inhomogeneous Li-composition profile results in a varied substrate index in the guiding layer, and the refractive index profile in the guiding layer is given.

2D profiling of tumor chemotactic and molecular phenotype at single cell resolution using a SERS-microfluidic chip

Emerging single-cell technologies create new opportunities for unraveling tumor heterogeneity.However,the development of high-content phenotyping platform is still at its infancy.Here,we develop a microfluidic chip for two-dimensional(2D)profiling of tumor chemotactic and molecular features at single cell resolution.Individual cells were captured by the triangular micropillar arrays in the cell-loading channel,facilitating downstream single-cell analysis.For 2D phenotyping,the chemotactic properties of tumor cells were visualized through cellular migratory behavior in microchannels,while their protein expression was profiled with multiplex surface enhanced Raman scattering(SERS)nanovectors,in which Raman reporter-embedded gold@silver core-shell nanoparticles(Au@Ag REPs)were modified with DNA aptamers targeting cellular surface proteins.As a proof of concept,breast cancer cells with diverse phenotypes were tested on the chip,demonstrating the capability of this platform for simultaneous chemotactic and molecular analysis.The chip is expected to provide a powerful tool for investigating tumor heterogeneity and promoting clinical precision medicine.