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Abstract When a few drops of acid (hydrochloric, acrylic, propionic, acetic, or formic) are added to a colloid comprised of 1D lepidocrocite titanate nanofilaments (1DLs)–2 × 2 TiO₆octahedra in cross‐section–a hydrogel forms, in many cases, within seconds. The 1DL synthesis process requires the reaction between titanium diboride with tetramethylammonium (TMA⁺), hydroxide. Using quantitative nuclear magnetic resonance (qNMR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC), the mass percent of TMA⁺after synthesis is determined to be ≈ 13.1 ± 0.1%. The TMA⁺is completely removed from the gels after 2 water soak cycles, resulting in the first completely inorganic, TiO₂‐based hydrogels. Ion exchanging the TMA⁺with hydronium results in gels with relatively strong hydrogen bonds. The hydrogels' compression strengths increased linearly with 1DL colloid concentration. At a 1DL concentration of 45 g L⁻¹, the compressive strength, at 80% deformation when acrylic acid is used, is ≈325 kPa. The strengths are ≈ 50% greater after the TMA⁺is removed. The removal of all residual organic components in the hydrogels, including TMA⁺, is confirmed by qNMR, Fourier‐transformed infrared spectroscopy (FTIR), and TGA/DSC. The 1DL phase is retained after gelation, TMA⁺removal, and 80% compression. 

Yiteng Zheng, Yue Qi, Junzhi Tan, Simon G. Podkolzin, Bruce E. Koel, "Selective Oxidation of Ethanol over Zeolite-Supported Gold Catalysts", North American Catalysis Society Meeting (NAM-27) Conference, New York, NY, 2022, Presentation number Wed-P-94. https://nam.confex.com/nam/2022/meetingapp.cgi/Paper/29726 

AlN thin films are enabling significant progress in modern optoelectronics, power electronics, and microelectromechanical systems. The various AlN growth methods and conditions lead to different film microstructures. In this report, phonon scattering mechanisms that impact the cross-plane (κz; along the c-axis) and in-plane (κr; parallel to the c-plane) thermal conductivities of AlN thin films prepared by various synthesis techniques are investigated. In contrast to bulk single crystal AlN with an isotropic thermal conductivity of ∼330 W/m K, a strong anisotropy in the thermal conductivity is observed in the thin films. The κz shows a strong film thickness dependence due to phonon-boundary scattering. Electron microscopy reveals the presence of grain boundaries and dislocations that limit the κr. For instance, oriented films prepared by reactive sputtering possess lateral crystalline grain sizes ranging from 20 to 40 nm that significantly lower the κr to ∼30 W/m K. Simulation results suggest that the self-heating in AlN film bulk acoustic resonators can significantly impact the power handling capability of RF filters. A device employing an oriented film as the active piezoelectric layer shows an ∼2.5× higher device peak temperature as compared to a device based on an epitaxial film. 

Abstract Ammonia-oxidizing archaea (AOA) are among the most abundant and ubiquitous microorganisms in the ocean, exerting primary control on nitrification and nitrogen oxides emission. Although united by a common physiology of chemoautotrophic growth on ammonia, a corresponding high genomic and habitat variability suggests tremendous adaptive capacity. Here, we compared 44 diverse AOA genomes, 37 from species cultivated from samples collected across diverse geographic locations and seven assembled from metagenomic sequences from the mesopelagic to hadopelagic zones of the deep ocean. Comparative analysis identified seven major marine AOA genotypic groups having gene content correlated with their distinctive biogeographies. Phosphorus and ammonia availabilities as well as hydrostatic pressure were identified as selective forces driving marine AOA genotypic and gene content variability in different oceanic regions. Notably, AOA methylphosphonate biosynthetic genes span diverse oceanic provinces, reinforcing their importance for methane production in the ocean. Together, our combined comparative physiological, genomic, and metagenomic analyses provide a comprehensive view of the biogeography of globally abundant AOA and their adaptive radiation into a vast range of marine and terrestrial habitats.