We study theoretically the effects of imperfect nesting in spin-density waves (SDW’s) in quasi-one-dimensional systems. We analyze the phase diagram, the specific heat, and the threshold electric field in the presence of imperfect nesting. The latter result appears to describe the temperature dependence of the threshold electric field observed in SDW’s of quenched di-tetramethyl-tetraselena-fulvalene chlorate [(TMTSF${)}_2$ ${\mathrm{ClO}}_4$] observed by Shimizu et al.

The volatile organic compounds (VOCs) in a wide spectrum of categories were identified as biomarkers in aquatic environments, playing an important role in marine and freshwater ecology and global atmospheric chemistry. VOCs released from biofuel have also attracted increasing attention. Although the importance has been recognized, the portable detection and analysis methods of VOC in aquatic systems have not yet been well developed and understood. In this work, we innovatively proposed an intelligent electrochemical sensing approach to classify and quantify VOCs in solution. Utilizing the cyclic voltammetry (CV) method with an ionic liquid-based electrolyte, we analyzed 50 μL samples of various VOC analytes, including acetic acid, acetone, dimethylformamide, dimethyl sulfoxide, ethanol, formaldehyde, formic acid, methanol, methyl formate, toluene, and a formaldehyde-methanol mixture, along with deionized water. The generated voltammograms were subsequently analyzed using our uniquely designed and optimized one-dimensional convolutional neural network (1D-CNN). This deep-learning algorithm achieved a 99.09% accuracy in VOCs classification validated through 5-fold cross-validation, and demonstrated an impressive 94.4% test accuracy for methanol detection within a 10 μL error range. For quantification, the system accurately categorized methanol volumes ranging from 0 to 50 μL in 10 μL increments, achieving a 98.18% accuracy. A notable linear correlation (R2 = 95.56%) was found between max current density at the oxidation peak and methanol volume, with the limit of detection at 9.3 μL. Such a sensing method exhibits potential for portability, high accuracy and generalization in the classification and quantification, ultimately reshaping the realm of VOC analysis in solution.

In the search for unconventional magnetism, exotic quantum states are characterized by a lack of order and a broad spin excitation continuum approaching zero temperature. We study the two-dimensional triangular-lattice effective spin- 1 2 system CeMgAl ₁₁ O ₁₉ , which shows slight disorder but no magnetic ordering down to 100 millikelvin. Spin-wave analysis in the magnetic-field–polarized state determines the spin Hamiltonian featuring a mixed ferromagnetic-antiferromagnetic nearest-neighbor exchange interaction [ J z = −0.024(5) milli–electron volts, J ⊥ = 0.056(3) milli–electron volts]. This places the system near an exactly solvable point of the spin- 1 2 triangular-lattice XXZ model ( J z = − 1 2 J ⊥ ) with extensive ground-state degeneracy. In zero field, neutron spectroscopy reveals a prominent continuum; we show that this arises from an ensemble average of spin-wave spectra across the degenerate ground-state manifold. This demonstrates that the role of weak quenched disorder can be quantitatively constrained: It inhibits unique ground-state selection and stabilizes a local distribution within the degenerate manifold, yielding continuum-like spectra that necessitate a critical reevaluation of the experimental signatures of exotic quantum states.

Parasitic reactions are responsible for continuous performance loss during the normal operation and storage of lithium-ion batteries, particularly for those using nickel-rich cathode materials. Among many contributors, residual Li₂CO₃ on the surface of nickel-rich cathodes plays a detrimental role in promoting parasitic reactions, and hence accelerates the performance loss of those cathode materials. In this work, a wet impregnation process was utilized to convert the detrimental Li₂CO₃ and LiOH impurities into a beneficial functional surface coating comprising phosphates. Specifically, hydro-phosphates were used as the functional surface modification agents to mitigate the detrimental effect of surface residuals. The best electrochemical performance was achieved by modifying LiNi_0.6Mn_0.2Co_0.2O₂ with a diluted dihydro-phosphate solution (pKa = 7.2), while the metal cation had a negligible impact on the electrochemical performance. This work provides a cheap and simple method for enabling the high performance of nickel-rich cathodes.