Characterization and Identification of NPK Stress in Rice Using Terrestrial Hyperspectral Images.

Due to nutrient stress, which is an important constraint to the development of the global agricultural sector, it is now vital to timely evaluate plant health. Remote sensing technology, especially hyperspectral imaging technology, has evolved from spectral response modes to pattern recognition and vegetation monitoring. This study established a hyperspectral library of 14 NPK (nitrogen, phosphorus, potassium) nutrient stress conditions in rice. The terrestrial hyperspectral camera (SPECIM-IQ) collected 420 rice stress images and extracted as well as analyzed representative spectral reflectance curves under 14 stress modes. The canopy spectral profile characteristics, vegetation index, and principal component analysis demonstrated the differences in rice under different nutrient stresses. A transformer-based deep learning network SHCFTT (SuperPCA-HybridSN-CBAM-Feature tokenization transformer) was established for identifying nutrient stress patterns from hyperspectral images while being compared with classic support vector machines, 1D-CNN (1D-Convolutional Neural Network), and 3D-CNN. The total accuracy of the SHCFTT model under different modeling strategies and different years ranged from 93.92% to 100%, indicating the positive effect of the proposed method on improving the accuracy of identifying nutrient stress in rice.

Mg/Al Double-Pillared LiNiO2 as a Co-Free Ternary Cathode Material Ensuring Stable Cycling at 4.6 V.

Cobalt-free (Co-free) and nickel-rich (Ni-rich) cathode materials have attracted significant attention and undergone extensive studies due to their affordability and superior energy density. However, the commercialization of these Co-free materials is hindered by challenges such as cation disorder, irreversible phase changes, and inadequate high-voltage performance. To overcome these challenges, a Co-free ternary cathode material of Mg/Al double-pillared LiNiO2 (NMA) synthesized via a wet-coating and lithiation-sintering technique is proposed. Fundamental studies reveal that Mg and Al have the potential to form a distinctive double-pillar structure within the layered cathode, enhancing its structural stability. To be specific, the strategic placement of Mg and Al in Li and Ni layers, respectively, effectively reduces Li+/Ni2+ disorder and prevents irreversible phase transitions. Additionally, the inclusion of Mg and Al refines the primary grains and compacts the secondary grains in the cathode material, reducing stress from cyclic usage and preventing material cracking, thereby mitigating electrolyte erosion. As a result, NMA demonstrates exceptional electrochemical performance under a high charge cutoff voltage of 4.6 V. It maintains 70% of initial specific capacity after 500 cycles at 1 C and exhibits excellent rate performance, with a capacity of 162 mAh g-1 at 5 C and 149 mAh g-1 at 10 C. As a whole, the produced NMA achieves a high structural stability in cases of excessive delithiation, providing a groundbreaking solution for the development of cost-effective and high-energy-density cathode materials for lithium-ion batteries.