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1. Large elastic anisotropy in Brillouin scattering of copper-intercalated GaS and GaSe

   https://doi.org/10.1063/5.0300066  

   Paulo-Wach, Daniel; Chen, Ethan; Nakamura, Masaru; Dubon, Oscar D; Koski, Kristie J (December 2025, Applied Physics Letters)

   Brillouin scattering of bulk layered hexagonal gallium sulfide (GaS) and gallium selenide (GaSe) was measured both as pristine materials and intercalated with copper and silver. The sound velocities, refractive index, and four of the five independent elastic stiffnesses (cij) were determined. Values of the c11 elastic stiffness in thin crystals are higher than in previous measurements, bringing the elastic anisotropy (c11/c33) into a range typical of other layered materials. Copper intercalation showed a larger effect on acoustic phonons in GaS than in GaSe. 

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2. Effect of structural water on the elasticity of orthopyroxene

   https://doi.org/10.2138/am-2021-7843  

   Hou, Mingqiang; Zhou, Wen-Yi; Hao, Ming; Hua, Florian Tian-Siang; Kung, Jennifer; Zhang, Dongzhou; Dera, Przemyslaw K.; Zhang, Jin S. (April 2022, American Mineralogist)

   Abstract As a major nominally anhydrous mineral (NAM) in the Earth’s upper mantle, orthopyroxene could host up to several hundred parts per million H2O in its crystal structure and transport the H2O to the deep Earth. To study the effect of structural H2O on the elasticity of orthopyroxene, we have measured the single-crystal elasticity of Mg1.991Al0.065Si1.951O6 with 842–900 ppm H2O and 1.64 ± 0.20 wt% Al2O3 at ambient conditions using Brillouin spectroscopy. The best-fit single-crystal elastic moduli (Cijs), bulk (KS0), and shear (G0) modulus of the hydrous Al-bearing orthopyroxene were determined as: C11 = 235(2) GPa, C22 = 173(2) GPa, C33 = 222(2) GPa, C44 = 86(1) GPa, C55 = 82(1) GPa, C66 = 82(1) GPa, C12 = 75(3) GPa, C13 = 67(2) GPa, and C23 = 49(2) GPa, KS0 = 111(2) GPa, and G0 = 78(1) GPa. Systematic analysis based on the results presented in this and previous studies suggests that the incorporation of 842–900 ppm H2O would increase C13 by 12.0(7)% and decrease C23 by 8.6(8)%. The effects on C11, C22, C33, C44, C66, KS0, and VP are subtle if not negligible when considering the uncertainties. The C55, C12, G0, and VS are not affected by the presence of structural H2O. Although laboratory experiments show that Fe,Al-bearing orthopyroxenes can host up to 0.8 wt% H2O in its structure, future high-pressure-temperature elasticity measurements on orthopyroxene with higher H2O content are needed to help better quantify this effect. 

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3. Ferrocene-Templated Synthesis of Fused Aminofulvenes: Elaboration of Chalaniline A and a Reversed Regioisomer via a Ferroceno[b]chromone

   https://doi.org/10.1055/a-2685-9280  

   Prapapongpan, Pannaporn; Nelson, Kylee B; Zakharov, Lev N; Blakemore, Paul R (October 2025, Synthesis)

   Ferrocenes were studied as cyclopentadiene ring surrogates enroute to non-metallocene targets such as the aminofulveno[1,2-b]chromone natural product chalaniline A. Ferroceno[b]chromone, as an archetype of interest, was prepared from ferrocenecarboxylic acid (4 steps, 24% yield) via N,N-diethyl 2-iodoferrocenecarboxamide by Ullmann etherification with phenol followed by LDA-mediated anionic cyclization. Reactivity studies revealed that this planar chiral analogue of xanthone readily fragments into non-metallocene products upon reaction with electrophiles. 1-Methoxy-3-methylferroceno[b]chromone, prepared similarly by substituting O-methylorcinol for phenol, was advanced to chalaniline A and a transposed regioisomer by concomitant deferration and demethylation with AlCl3; formylation of the resulting cyclopentadiene-fused chromone with excess Vilsmeier reagent; and then Pinnick oxidation (NaClO2), methylation (TMSCHN2), and final transamination (PhNH2). Four compounds, including ferroceno[b]chromone and the C11/C12-transposed regioisomer of chalaniline A, were characterized by single crystal X-ray diffraction analysis. 

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4. Production of oxygenated volatile organic compounds from the ozonolysis of coastal seawater

   https://doi.org/10.5194/acp-24-3729-2024  

   Kilgour, Delaney B; Novak, Gordon A; Claflin, Megan S; Lerner, Brian M; Bertram, Timothy H (January 2024, Atmospheric Chemistry and Physics)

   Abstract. Dry deposition of ozone (O3) to the ocean surface and the ozonolysis of organics in the sea surface microlayer (SSML) are potential sources of volatile organic compounds (VOCs) to the marine atmosphere. We use a gas chromatography system coupled to a Vocus proton-transfer-reaction time-of-flight mass spectrometer to determine the chemical composition and product yield of select VOCs formed from ozonolysis of coastal seawater collected from Scripps Pier in La Jolla, California. Laboratory-derived results are interpreted in the context of direct VOC vertical flux measurements made at Scripps Pier. The dominant products of laboratory ozonolysis experiments and the largest non-sulfur emission fluxes measured in the field correspond to Vocus CxHy+ and CxHyOz+ ions. Gas chromatography (GC) analysis suggests that C5–C11 oxygenated VOCs, primarily aldehydes, are the largest contributors to these ion signals. In the laboratory, using a flow reactor experiment, we determine a VOC yield of 0.43–0.62. In the field at Scripps Pier, we determine a maximum VOC yield of 0.04–0.06. Scaling the field and lab VOC yields for an average O3 deposition flux and an average VOC structure results in an emission source of 10.7 to 167 Tg C yr−1, competitive with the DMS source of approximately 20.3 Tg C yr−1. This study reveals that O3 reactivity to dissolved organic carbon can be a significant carbon source to the marine atmosphere and warrants further investigation into the speciated VOC composition from different seawater samples and the reactivities and secondary organic aerosol (SOA) yields of these molecules in marine-relevant, low NOx conditions. 

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5. Hydrogen Effect on the Sound Velocities of Upper Mantle Omphacite

   https://doi.org/10.3390/min9110690  

   Mans, Wade; Zhang, Jin S.; Hao, Ming; Smyth, Joseph R.; Zhang, Dongzhou; Finkelstein, Gregory J.; Dera, Przemyslaw (November 2019, Minerals)

   Clinopyroxene (Cpx) is commonly believed to be the best structural water (hydrogen) carrier among all major upper mantle nominally anhydrous minerals (NAMs). In this study, we have measured the single-crystal elastic properties of a Cpx, a natural omphacite with ~710 ppm water at ambient pressure (P) and temperature (T) conditions. Utilizing the single-crystal X-ray diffraction (XRD) and electron microprobe data, the unit cell parameters and density were determined as a = 9.603(9) Å, b = 8.774(3) Å, c = 5.250(2) Å, β = 106.76(5)o, V = 255.1(4) Å3, and ρ = 3.340(6) g/cm3. We performed Brillouin spectroscopy experiments on four single crystals along a total of 52 different crystallographic directions. The best-fit single-crystal elastic moduli (Cijs), bulk and shear moduli were determined as: C11 = 245(1) GPa, C22 = 210(2) GPa, C33 = 249.6(9) GPa, C44 = 75.7(9) GPa, C55 = 71.2(5) GPa, C66 = 76(1) GPa, C12 = 85(2) GPa, C13 = 70(1) GPa, C23 = 66(2) GPa, C15 = 8.0(6) GPa, C25 = 6(1) GPa, C35 = 34.7(6) GPa, and C46 = 8.7(7) GPa, KS0 = 125(3) GPa, and G0 = 75(2) GPa, respectively. Compared with the anticipated elastic properties of an anhydrous omphacite with the same chemical composition, our results indicate that the incorporation of ~710 ppm structural water has no resolvable effect on the aggregate elastic properties of omphacite, although small differences (up to ~9 GPa) were observed in C13, C25, C44, and C66. 

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