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1. Palomar discovery and initial characterization of naked-eye long-period comet C/2022 E3 (ZTF)

   https://doi.org/10.1093/mnrasl/slad139  

   Bolin, B. T.; Masci, F. J.; Duev, D. A.; Milburn, J. W.; Neill, J. D.; Purdum, J. N.; Avdellidou, C.; Saki, M.; Cheng, Y-C; Delbo, M.; et al (September 2023, Monthly Notices of the Royal Astronomical Society: Letters)

   ABSTRACT Long-period comets are planetesimal remnants constraining the environment and volatiles of the protoplanetary disc. We report the discovery of hyperbolic long-period comet C/2022 E3 Zwicky Transient Facility (ZTF), which has a perihelion ∼1.11 au, an eccentricity ≳1 and an inclination ∼109°, from images taken with the Palomar 48-inch telescope during morning twilight on 2022 March 2. Additionally, we report the characterization of C/2022 E3 (ZTF) from observations taken with the Palomar 200-inch, the Palomar 60-inch, and the NASA Infrared Telescope Facility in early 2023 February to 2023 March when the comet passed within ∼0.28 au of the Earth and reached a visible magnitude of ∼5. We measure g–r = 0.70 ± 0.01, r–i = 0.20 ± 0.01, i–z = 0.06 ± 0.01, z–J = 0.90 ± 0.01, J–H = 0.38 ± 0.01, and H–K = 0.15 ± 0.01 colours for the comet from observations. We measure the A(0°)fρ (0.8 μm) in a 6500 km radius from the nucleus of 1483 ± 40 cm, and CN, C3, and C2 production of 5.43 ± 0.11 × 1025, 2.01 ± 0.04 × 1024, and 3.08 ± 0.5 × 1025 mol s−1, similar to other long-period comets. We additionally observe the appearance of jet-like structures at a scale of ∼4000 km in wide-field g-band images, which may be caused by the presence of CN gas in the near-nucleus coma. 

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2. Cycling Performance and Mechanistic Insights of Ferricyanide Electrolytes in Alkaline Redox Flow Batteries

   https://doi.org/10.1002/aenm.202203762  

   Hu, Maowei; Wang, Abigail_P; Luo, Jian; Wei, Qianshun; Liu, T_Leo (March 2023, Advanced Energy Materials)

   Abstract Ferrocyanide, such as K₄[Fe(CN)₆], is one of the most popular cathode electrolyte (catholyte) materials in redox flow batteries. However, its chemical stability in alkaline redox flow batteries is debated. Mechanistic understandings at the molecular level are necessary to elucidate the cycling stability of K₄[Fe(CN)₆] and its oxidized state (K₃[Fe(CN)₆]) based electrolytes and guide their proper use in flow batteries for energy storage. Herein, a suite of battery tests and spectroscopic studies are presented to understand the chemical stability of K₄[Fe(CN)₆] and its charged state, K₃[Fe(CN)₆], at a variety of conditions. In a strong alkaline solution (pH 14), it is found that the balanced K₄[Fe(CN)₆]/K₃[Fe(CN)₆] half‐cell experiences a fast capacity decay under dark conditions. The studies reveal that the chemical reduction of K₃[Fe(CN)₆] by a graphite electrode leads to the charge imbalance in the half‐cell cycling and is the major cause of the observed capacity decay. In addition, at pH 14, K₃[Fe(CN)₆] undergoes a slow CN^‐/OH^‐exchange reaction. The dissociated CN^‐ligand can chemically reduce K₃[Fe(CN)₆] to K₄[Fe(CN)₆] and it is converted to cyanate (OCN^‐) and further, decomposes into CO₃^2‐and NH₃. Ultimately, the irreversible chemical conversion of CN^‐to OCN^‐leads to the irreversible decomposition of K₄/K₃[Fe(CN)₆] at pH 14. 

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3. The Scandium(II) Carbonyl Complex (C ₅ H ₂ ^t Bu ₃ ) ₂ Sc(CO) and Its Isocyanide Analog (C ₅ H ₂ ^t Bu ₃ ) ₂ Sc(CNC ₆ H ₃ Me ₂ -2,6)

   https://doi.org/10.1021/jacs.4c09021  

   Queen, Joshua D; Goudzwaard, Quinn E; Rajabi, Ahmadreza; Ziller, Joseph W; Furche, Filipp; Evans, William J (September 2024, Journal of the American Chemical Society)

   Treatment of the scandium(II) metallocene Cpttt2Sc (Cpttt = C5H2tBu3) with CO or the isocyanide CNXyl (Xyl = C6H3Me2-2,6) yields the carbonyl complex Cpttt2Sc(CO), 1, or the isocyanide complex Cpttt2Sc(CNXyl), 2, which were identified by X-ray crystallography. Isotopic labeling with 13CO shows the CO stretch of 1 at 1875 cm−1 shifts to 1838 cm−1 in 1-13CO. The CN stretch in 2 is shifted to 1939 cm−1 compared to 2118 cm−1 for the free isocyanide. The 80.1 MHz (28.7 G) 45Sc hyperfine coupling in 1 and 74.7 MHz (26.8 G) in 2 are similar to the 82.6 MHz (29.6 G) coupling constant in Cpttt2Sc and indicate that 1 and 2 are Sc(II) complexes. A comprehensive analysis of the electronic structures of 1 and 2 using DFT calculations is reported. 

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4. Concentration-gradient Prussian blue cathodes for Na-ion batteries

   Hu P.P, Peng W.P (January 2020, ACS energy letters)

   A concentration-gradient composition is proposed as an effective approach to solve the mechanical degradation and improve the electrochemical cyclability for cathodes of sodium-ion batteries. Concentration-gradient shell NaxNiyMn1-yFe(CN)6·nH2O, in which the Ni content gradually increases from the interior to the particle surface, is synthesized by a facile co-precipitation process. The as-obtained cathode exhibits an improved electrochemical performance compared to homogeneous NaxMnFe(CN)6·nH2O, delivering a high reversible specific capacity of 110 mA h g-1 at 0.2 C and outstanding cycling stability (93% retention after 1000 cycles at 5 C). The improvement of electrochemical performance can be attributed to its robust microstructure that effectively alleviates the electrochemically induced stresses and accumulated damage during sodiation/desodiation and thus prevents the initiation of fracture in the particles upon long term cycling. These findings render a prospective strategy to develop high-performance electrode materials for sodium-ion batteries. 

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5. Concentration-Gradient Prussian Blue Cathodes for Na-Ion Batteries

   Hu P., Peng W. (January 2020, ACS energy letters)

   A concentration-gradient composition is proposed as an effective approach to solve the mechanical degradation and improve the electrochemical cyclability for cathodes of sodium-ion batteries. Concentration-gradient shell NaxNiyMn1-yFe(CN)6·nH2O, in which the Ni content gradually increases from the interior to the particle surface, is synthesized by a facile co-precipitation process. The as-obtained cathode exhibits an improved electrochemical performance compared to homogeneous NaxMnFe(CN)6·nH2O, delivering a high reversible specific capacity of 110 mA h g-1 at 0.2 C and outstanding cycling stability (93% retention after 1000 cycles at 5 C). The improvement of electrochemical performance can be attributed to its robust microstructure that effectively alleviates the electrochemically induced stresses and accumulated damage during sodiation/desodiation and thus prevents the initiation of fracture in the particles upon long term cycling. These findings render a prospective strategy to develop high-performance electrode materials for sodium-ion batteries. 

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