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Lithium metal is an ideal anode material for next-generation electrical energy storage because of its high specific capacity. However, uncontrolled growth of Li dendrites during deposition and stripping processes results in low coulombic efficiency and severe safety concerns. Here we report a porous and robust coating of metal-organic framework (MOF-199), which could physically suppress the growth of lithium dendrite by acting as a robust shield, and homogenize Li-ion concentration by its high-polarity structure, thereby relieving excess SEI formation. In addition, another MOF (ZIF-8) layer is also confirmed to effectively hinder the formation and penetration of Li dendrites. The MOF particle size in the coating layer is shown to be a key factor determining the level of protection. Finally, the ability of the MOF-199 layer to protect Na metal anodes is studied. Image 1 • A porous and robust coating of MOFs is fabricated to protect Li metal anode. • The nano-MOFs based layer results in a dense lithium deposit. • The MOF particle size is a key factor in protecting Li metal anode. • MOFs layer could effectively protect Na metal anode. [ABSTRACT FROM AUTHOR]

• 16 Muller matrix elements measurement at a single shot. • Spatial polarization modulation in both PSG and PSA by using vortex retarders. • No rotating and active elements involved. • Model free calibration method: modulation vector calibration method (MVCM). • Compact configuration; stable, fast and accurate measurement. We propose a dual vortex retarder Mueller matrix ellipsometry (DVRMME) that can extract 16 Mueller matrix elements by analyzing a single intensity image. Two customized vortex quarter wave retarders (VQWRs) with different orders are employed to realize the spatial modulation in the polarization state generation (PSG) and polarization state analyzing (PSA) arms. Due to the spatial polarization modulation by VQWRs, a pattern with regularly varying intensity along the azimuth direction is formed, and the sample's Mueller matrix can be obtained by processing the modulated intensity image. The ellipsometry's working principle has been elaborated by the Stokes-Mueller formalism, and its main error sources are presented and analyzed, and then a modulation vector calibration method is proposed to reduce the measurement error. To verify the validity of the scheme, the DVRMME has been constructed and demonstrated in experiment. The Mueller matrices of air, polarizer and retarder were measured, and their RMS errors of 16 Mueller matrix elements were respectively less than 0.0110, 0.0094 and 0.0180, and their maximum absolute errors were respectively less than 0.0196, 0.0230 and 0.0352. [ABSTRACT FROM AUTHOR]

The vortex retarder based spatially modulated polarimeter provides a promising polarization measurement technique with rapidness, compactness, simplicity and stability. However, such a technique faces the challenging problem of calibration that has not yet been addressed, which significantly constrains its potential broad applications. In this paper, we study the total effects of different error sources that limit the measurement precision of the vortex retarder based spatially modulated polarimeter, and propose an efficient calibration method to reduce the errors. A theoretical model is established to analyze the general effects of the different error sources on the intensity modulation curve of the incident waves with the Stokes-Mueller formalism. It is revealed that the error of the intensity modulation curve of any incident beam can be calculated, simply through those error curves of the beams polarized at 0 and 45°. Calibration experiments of incident beams with different polarization directions are presented, verifying that our proposed method is efficient, accurate and easy to implement. Moreover, our approach can effectively reduce the Stokes parameters' measurement error from about 0.05 to <0.01, which is superior to several typical commercial polarimeters. [ABSTRACT FROM AUTHOR]

Abstract: Automatic detection of fruit peel defects by a computer vision system is difficult due to the challenges of acquiring images from the surface of spherical fruit and the visual similarity between the stem-ends and the true defects. In this study, oranges with wind scarring, thrips scarring, scale infestation, dehiscent fruit, anthracnose, copper burn, canker spot and normal surface were researched. A lighting transform method based on a low pass Butterworth filter with a cutoff frequency D 0 =7 was first developed to convert the non-uniform intensity distribution on spherical oranges into a uniform intensity distribution over the whole fruit surface. However, the stem-ends were easily confused with defective areas. In order to solve this problem, different color components (R, G and B) and their combinations were analyzed. It was found that a ratio method and R and G component combination coupled with a big area and elongated region removal algorithm (BER) could be used to differentiate stem-ends from defects effectively. Finally, a processing and classification algorithm based on a simple thresholding method was proposed. The result with 98.9% overall detection rate for the 720 independent sample images indicated that the proposed algorithm was effective in differentiation of normal and defective oranges. The method, however, could not discriminate between different types of defects. [Copyright &y& Elsevier]