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1. Synthesis of Ni–TiO Nanocomposites as Enzyme–Less, Amperometric Sensors for the Electrooxidation of Glucose

   https://doi.org/10.1149/2754-2734/acd404  

   de los Rios, J. P.; Galvan, Vicente; Prakash, G. K. (May 2023, ECS Advances)

   The simple synthesis of a Ni–TiO₂nanocomposite supported on Vulcan carbon (XC–72 R) for the electrooxidation reaction of glucose is reported. Four transition metal weight ratios were synthesized and characterized. Cyclic voltammetry studies in 0.1 M NaOH demonstrate that the four metal catalysts can effectively oxidize 1 mM glucose, with the 3:1 (60%) Ni to Ti nanocomposite yielding the highest current. The 60% Ni–TiO₂/XC72R catalyst was used to construct an enzyme–less, chronoamperometric sensor for glucose detection in an alkaline medium. Using 50μM aliquots of glucose at a potential of +0.7 V (vs Hg/HgO), the sensor responded rapidly (<3 s), provided a sensitivity of 3300μA mM⁻¹cm⁻², detection limits of 144 nM (Signal/Noise = 3), and excellent selectivity and reproducibility. The glucose aliquot concentrations were then increased to 1 mM to mimic physiological blood conditions of 1–20 mM. At a potential of +0.7 V (vs Hg/HgO), the sensor continued to respond rapidly (<1 s), showed a sensitivity of 273.7μA mM⁻¹cm⁻², detection limits of 3.13μM (S/N = 3), and excellent selectivity and reproducibility. The catalyst also exhibited an ideal anti–poisoning capability to free chloride ions and negligible signals towards other interfering species. 

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2. A [C ii ] 158 μ m Survey of Damped Lyα Absorber Galaxies at z  ∼ 4: Observations of Dense and Metal-enriched Neutral Gas within the Circumgalactic Medium of Star-forming Galaxies

   https://doi.org/10.3847/1538-4357/adbbd1  

   Neeleman, Marcel; Kanekar, Nissim; Prochaska, J Xavier; Rafelski, Marc A; Kahinga, Lordrick A (April 2025, The Astrophysical Journal)

   Abstract We present a survey undertaken with the Atacama Large Millimeter/submillimeter Array (ALMA) to study the galaxies associated with a representative sample of 16 damped Lyαabsorbers (DLAs) atz ≈ 4.1–4.5, using the [Cii] 158μm ([Cii]) line. We detect seven [Cii]-emitting galaxies in the fields of five DLAs, all of which have absorption metallicity [M/H] > −1.5. We find that the detectability of these Hi-selected galaxies with ALMA is a strong function of DLA metallicity, with a detection rate of $71_{-20}^{+11}$% for DLAs with [M/H] > −1.5 and 0⁺¹⁸% for DLAs with [M/H] < −1.5. The identified DLA galaxies have far-IR properties similar to those of typical star-forming galaxies atz ∼ 4, with estimated obscured star formation rates ranging from ≲6M_⊙yr⁻¹to 110M_⊙yr⁻¹. High-metallicity DLAs therefore provide an efficient way to identify and study samples of high-redshift, star-forming galaxies, without preselecting the galaxies by their emission properties. The agreement between the velocities of the metal absorption lines of the DLA and the [Cii] emission line of the DLA galaxy indicates that the metals within the DLA originated in the galaxy. With observed impact parameters between 14 and 59 kpc, this indicates that star-forming galaxies atz ∼ 4 have a substantial reservoir of dense, cold, neutral gas within their circumgalactic medium that has been enriched with metals from the galaxy. 

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3. ALMA Reveals Extended Cool Gas and Hot Ionized Outflows in a Typical Star-forming Galaxy at Z = 7.13

   https://doi.org/10.3847/1538-4357/ac795b  

   Akins, Hollis B.; Fujimoto, Seiji; Finlator, Kristian; Watson, Darach; Knudsen, Kirsten K.; Richard, Johan; C. Bakx, Tom J. L.; Hashimoto, Takuya; Inoue, Akio K.; Matsuo, Hiroshi; et al (July 2022, The Astrophysical Journal)

   Abstract We present spatially resolved morphological properties of [CII] 158μm, [OIII] 88μm, dust, and rest-frame ultraviolet (UV) continuum emission for A1689-zD1, a strongly lensed, sub-L* galaxy atz= 7.13, by utilizing deep Atacama Large Millimeter/submillimeter Array (ALMA) and Hubble Space Telescope (HST) observations. While the [OIII] line and UV continuum are compact, the [CII] line is extended up to a radius ofr∼ 12 kpc. Using multi-band rest-frame far-infrared continuum data ranging from 52 to 400μm, we find an average dust temperature and emissivity index of $T_{\mathrm{dust}}={41}_{-14}^{+17}$K and $\beta ={1.7}_{-0.7}^{+1.1}$, respectively, across the galaxy. We find slight differences in the dust continuum profiles at different wavelengths, which may indicate that the dust temperature decreases with distance. We map the star formation rate (SFR) via IR and UV luminosities and determine a total SFR of 37 ± 1M_⊙yr⁻¹with an obscured fraction of 87%. While the [OIII] line is a good tracer of the SFR, the [CII] line shows deviation from the localL_[CII]-SFR relations in the outskirts of the galaxy. Finally, we observe a clear difference in the line profile between [CII] and [OIII], with significant residuals (∼5σ) in the [OIII] line spectrum after subtracting a single Gaussian model. This suggests a possible origin of the extended [CII] structure from the cooling of hot ionized outflows. The extended [CII] and high-velocity [OIII] emission may both contribute in part to the highL_[OIII]/L_[CII]ratios recently reported inz> 6 galaxies. 

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4. Multiphase ISM in the z = 5.7 Hyperluminous Starburst SPT 0346–52

   https://doi.org/10.3847/1538-4357/ac58f9  

   Litke, Katrina C.; Marrone, Daniel P.; Aravena, Manuel; Béthermin, Matthieu; Chapman, Scott C.; Dong, Chenxing; Hayward, Christopher C.; Hill, Ryley; Jarugula, Sreevani; Malkan, Matthew A.; et al (April 2022, The Astrophysical Journal)

   Abstract With Σ_SFR∼ 4200M_⊙yr⁻¹kpc⁻², SPT 0346–52 (z= 5.7) is the most intensely star-forming galaxy discovered by the South Pole Telescope. In this paper, we expand on previous spatially resolved studies, using ALMA observations of dust continuum, [Nii] 205μm, [Cii] 158μm, [Oi] 146μm, and undetected [Nii] 122μm and [Oi] 63μm emission to study the multiphase interstellar medium (ISM) in SPT 0346–52. We use pixelated, visibility-based lens modeling to reconstruct the source-plane emission. We also model the source-plane emission using the photoionization codecloudyand find a supersolar metallicity system. We calculateT_dust= 48.3 K andλ_peak= 80μm and see line deficits in all five lines. The ionized gas is less dense than comparable galaxies, withn_e< 32 cm⁻³, while ∼20% of the [Cii] 158μm emission originates from the ionized phase of the ISM. We also calculate the masses of several phases of the ISM. We find that molecular gas dominates the mass of the ISM in SPT 0346–52, with the molecular gas mass ∼4× higher than the neutral atomic gas mass and ∼100× higher than the ionized gas mass. 

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5. PHANGS–JWST First Results: A Global and Moderately Resolved View of Mid-infrared and CO Line Emission from Galaxies at the Start of the JWST Era

   https://doi.org/10.3847/2041-8213/acab01  

   Leroy, Adam_K; Bolatto, Alberto_D; Sandstrom, Karin; Rosolowsky, Erik; Barnes, Ashley_T; Bigiel, F.; Boquien, Médéric; den_Brok, Jakob_S; Cao, Yixian; Chastenet, Jérémy; et al (February 2023, The Astrophysical Journal Letters)

   Abstract We explore the relationship between mid-infrared (mid-IR) and CO rotational line emission from massive star-forming galaxies, which is one of the tightest scalings in the local universe. We assemble a large set of unresolved and moderately (∼1 kpc) spatially resolved measurements of CO (1–0) and CO (2–1) intensity,I_CO, and mid-IR intensity,I_MIR, at 8, 12, 22, and 24μm. TheI_COversusI_MIRrelationship is reasonably described by a power law with slopes 0.7–1.2 and normalizationI_CO∼ 1 K km s⁻¹atI_MIR∼ 1 MJy sr⁻¹. Both the slopes and intercepts vary systematically with choice of line and band. The comparison between the relations measured for CO (1–0) and CO (2–1) allow us to infer that $R_{21}\propto I_{\mathrm{MIR}}^{0.2}$, in good agreement with other work. The 8μm and 12μm bands, with strong polycyclic aromatic hydrocarbon (PAH) features, show steeper CO versus mid-IR slopes than the 22 and 24μm, consistent with PAH emission arising not just from CO-bright gas but also from atomic or CO-dark gas. The CO-to-mid-IR ratio correlates with global galaxy stellar mass (M_⋆) and anticorrelates with star formation rate/M_⋆. At ∼1 kpc resolution, the first four PHANGS–JWST targets show CO-to-mid-IR relationships that are quantitatively similar to our larger literature sample, including showing the steep CO-to-mid-IR slopes for the JWST PAH-tracing bands, although we caution that these initial data have a small sample size and span a limited range of intensities. 

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