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The climatology of earth's Na density over Fort Collins, CO (41°N, 105°W) based on nocturnal Na lidar observations between 1990 and 1999 was reported by She et al. (2000,https://doi.org/10.1029/2000gl003825). Based on a continued 28‐year data set between 1990 and 2017 with the latter part observed over Logan, UT (42N, 112W), we update the seasonal variations between 80 and 110 km. This data set is also used to deduce long‐term responses of Na density (profile) between 75 and 110 km, showing a positive linear trend between 75 and 93 km (with maximum ∼2.87 × 10⁸ m⁻³/decade at 87 km); it turns negative before approaching zero at 110 km (with minimum ∼−2.96 × 10⁷ m⁻³/decade at 100 km). The associated solar response is also positive for the altitude range in question (with maximum ∼5.20 × 10⁶ m⁻³/SFU at 91 km). We also derived the 28‐year mean Na layer column abundance, centroid altitude, and root mean square width to be 3.92 ± 2.14 10¹³ m⁻², 91.3 ± 1.0 km, and 4.62 ± 0.56 km, respectively, and deduced long‐term trend and solar cycle responses of column abundance and centroid altitude, respectively to be 7.81 ± 1.63%/decade and 16.9 ± 2.8%/100SFU, and −355 ± 35 m/decade and −1.94 ± 0.69 m/SFU. We explained conceptually how positive long‐term responses in Na density led to positive responses in column abundance and negative responses in centroid altitude.

 

The development of anode materials with high-rate capability is critical to high-power lithium batteries. T-Nb 2 O 5 has been widely reported to exhibit pseudocapacitive behavior and fast lithium storage capability. However, the other polymorphs of Nb 2 O 5 prepared at higher temperatures have the potential to achieve even higher specific capacity and tap density than T-Nb 2 O 5 , offering higher volumetric power and energy density. Here, micrometer-sized H-Nb 2 O 5 with rich Wadsley planar defects (denoted as d-H-Nb 2 O 5 ) is designed for fast lithium storage. The performance of H-Nb 2 O 5 with local rearrangements of [NbO 6 ] octahedra blocks surpasses that of T-Nb 2 O 5 in terms of specific capacity, rate capability, and stability. A wide range variation in the valence of niobium ions upon lithiation was observed for defective H-Nb 2 O 5 via operando X-ray absorption spectroscopy. Operando extended X-ray absorption fine structure and ex situ Raman spectroscopy analyses reveal a large and reversible distortion of the structure in the two-phase region. Computation and ex situ X-ray diffraction analysis reveal that the shear structure expands along major lithium diffusion pathways and contracts in the direction perpendicular to the shear plane. Planar defects relieve strain through perpendicular arrangements of blocks, minimizing volume change and enhancing structural stability. In addition, strong Li adsorption on planar defects enlarges intercalation capacity. Different from nanostructure engineering, our strategy to modify the planar defects in the bulk phase can effectively improve the intrinsic properties. The findings in this work offer new insights into the design of fast Li-ion storage materials in micrometer sizes through defect engineering, and the strategy is applicable to the material discovery for other energy-related applications. 

This paper proposes a differential burn-in policy that considers the spatial nonhomogeneous distribution of defects in semiconductor manufacturing. Due to the nonhomogeneous distribution of spatial defects, devices at different locations on a semiconductor wafer may exhibit different probabilities of being defective. Unlike conventional burn-in policies, which subject all devices to the same burn-in test, the differential burn-in policy can take different actions for different devices, i.e., acceptance without burn-in, rejection without burn-in, or burn-in with a certain duration. A mixed integer nonlinear programming model is developed to find the cost-optimal decisions. A numerical example is used to demonstrate the potential application of the proposed burn-in policy. 

Abstract. Lidar observations of the mesospheric Na layer have revealed considerablediurnal variations, particularly on the bottom side of the layer, where morethan an order-of-magnitude increase in Na density has been observed below 80 kmafter sunrise. In this paper, multi-year Na lidar observations areutilized over a full diurnal cycle at Utah State University (USU) (41.8^∘ N,111.8^∘ W) and a global atmospheric model of Na with 0.5 kmvertical resolution in the mesosphere and lower thermosphere (WACCM-Na) to explorethe dramatic changes of Na density on the bottom side of the layer. Photolysis of the principal reservoir NaHCO₃ is shown to beprimarily responsible for the increase in Na after sunrise, amplified by theincreased rate of reaction of NaHCO₃ with atomic H, which is mainlyproduced from the photolysis of H₂O and the reaction of OH withO₃. This finding is further supported by Na lidar observation at USUduring the solar eclipse (>96 % totality) event on 21 August 2017, when a decrease and recovery of the Na density on thebottom side of the layer were observed. Lastly, the model simulation showsthat the Fe density below around 80 km increases more strongly and earlierthan observed Na changes during sunrise because of the considerably fasterphotolysis rate of its major reservoir of FeOH.