Dissolved rare earth elements estimation of ion-absorption rare earth ores using reflectance spectroscopy in south Jiangxi province,China

Ion-absorption rare earth ores are an important mineral resource in China.Nowadays,the unauthorized mining has become a serious problem,resulting in severe water pollution and the wastage of rare earth elements(REEs).Being able to estimate the concentration of dissolved REEs in water bodies near mines is essential for tackling this environmental problem.Conventionally,quantitative analyses of the contents of dissolved REEs are performed using laboratory-based techniques,which can be time consuming and costly.Spectral reflectance is a rapid and cost-effective means of characterizing the chemical compositions of light-absorbing materials.In this study,reflectance spectroscopy was performed on dissolved REEs,and the correlation between their reflectance characteristics and REE content was determined.A total of 50 aqueous media samples collected in south Jiangxi Province and 25 laboratory-produced aqueous media samples were tested,and their reflectance spectra and REE contents were measured using reflectance spectroscopy and inductively coupled plasma mass spectrometry,respectively.Next,the reflectance,differential reflectance,and absorption depth were analysed based on the REE content.Six diagnostic absorption features related to REEs are recognised in the visible and near-infrared wavelength regions,along with several smaller peaks.It indicates that the results of the absorption depth analysis are in accordance with the absorption spectra characteristics of the REEs,with the R2 value being higher than 0.97.The intensity of each of the six absorption bands exhibits a linear correlation to the total REE content.Therefore,linear regressio n models can be derived for estimating the total concentration of REEs in aqueous media samples.What’s more,the detection limit for REEs is determined to be about 30μg/L.Thus,it can be concluded that reflectance spectroscopy is a suitable technique for estimating the concentration of dissolved REEs.

Slide-free histological imaging by microscopy with ultraviolet surface excitation using speckle illumination

Microscopy with ultraviolet surface excitation(MUSE)is a promising slide-free imaging technique to improve the time-consuming histopathology workflow.However,since the penetration depth of the excitation light is tissue dependent,the image contrast could be significantly degraded when the depth of field of the imaging system is shallower than the penetration depth.High-resolution cellular imaging normally comes with a shallow depth of field,which also restricts the tolerance of surface roughness in biological specimens.Here we propose the incorporation of MUSE with speckle illumination(termed MUSES),which can achieve sharp imaging on thick and rough specimens.Our experimental results demonstrate the potential of MUSES in providing histological images with~1μm spatial resolution and improved contrast,within 10 minutes for a field of view of 1.7 mm×1.2 mm.With the extended depth of field feature,MUSES also relieves the constraint of tissue flatness.Furthermore,with a color transformation assisted by deep learning,a virtually stained histological image can be generated without manual tuning,improving the applicability of MUSES in clinical settings.