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1. Resolving the contrasting leaf hydraulic adaptation of C₃ and C₄ grasses

   https://doi.org/10.1111/nph.20341  

   Baird, Alec S; Taylor, Samuel H; Pasquet‐Kok, Jessica; Vuong, Christine; Zhang, Yu; Watcharamongkol, Teera; Cochard, Hervé; Scoffoni, Christine; Edwards, Erika J; Osborne, Colin P; et al (March 2025, New Phytologist)

   Summary Grasses are exceptionally productive, yet their hydraulic adaptation is paradoxical. Among C₃grasses, a high photosynthetic rate (A_area) may depend on higher vein density (D_v) and hydraulic conductance (K_leaf). However, the higherD_vof C₄grasses suggests a hydraulic surplus, given their reduced need for highK_leafresulting from lower stomatal conductance (g_s).Combining hydraulic and photosynthetic physiological data for diverse common garden C₃and C₄species with data for 332 species from the published literature, and mechanistic modeling, we validated a framework for linkages of photosynthesis with hydraulic transport, anatomy, and adaptation to aridity.C₃and C₄grasses had similarK_leafin our common garden, but C₄grasses had higherK_leafthan C₃species in our meta‐analysis. Variation inK_leafdepended on outside‐xylem pathways. C₄grasses have highK_leaf : g_s, which modeling shows is essential to achieve their photosynthetic advantage.Across C₃grasses, higherA_areawas associated with higherK_leaf, and adaptation to aridity, whereas for C₄species, adaptation to aridity was associated with higherK_leaf : g_s. These associations are consistent with adaptation for stress avoidance.Hydraulic traits are a critical element of evolutionary and ecological success in C₃and C₄grasses and are crucial avenues for crop design and ecological forecasting. 

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2. Contracting eastern African C4 grasslands during the extinction of Paranthropus boisei

   https://doi.org/10.1038/s41598-021-86642-z  

   Quinn, Rhonda L.; Lepre, Christopher J. (December 2021, Scientific Reports)

   Abstract The extinction of theParanthropus boiseiestimated to just before 1 Ma occurred when C₄grasslands dominated landscapes of the Eastern African Rift System (EARS).P. boiseihas been characterized as an herbivorous C₄specialist, and paradoxically, its demise coincided with habitats favorable to its dietary ecology. Here we report new pedogenic carbonate stable carbon (δ¹³C_PC) and oxygen (δ¹⁸O_PC) values (nodules = 53, analyses = 95) from an under-sampled interval (1.4–0.7 Ma) in the Turkana Basin (Kenya), one of the most fossiliferous locales ofP. boisei. We combined our new results with published δ¹³C_PCvalues from the EARS dated to 3–0 Ma, conducted time-series analysis of woody cover (ƒ_WC), and compared the EARS ƒ_WCtrends to regional and global paleo-environmental and -climatic datasets. Our results demonstrate that the long-term rise of C₄grasslands was punctuated by a transient but significant increase in C₃vegetation and warmer temperatures, coincident with the Mid-Pleistocene Transition (1.3–0.7 Ma) and implicating a short-term rise inpCO₂. The contraction of C₄grasslands escalated dietary competition amongst the abundant C₄-feeders, likely influencingP. boisei’s demise. 

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3. Activity and Selectivity in the Electrochemical Reduction of CO ₂ at CuSnx Electrocatalysts Using a Zero-Gap Membrane Electrode Assembly

   https://doi.org/10.1149/1945-7111/ad6fd7  

   Dauda, Monsuru; Hendershot, John; Bello, Mustapha; Park, Junghyun; Orduz, Alvaro Loaiza; Kizilkaya, Orhan; Sprunger, Phillip; Engler, Anthony; Yao, Koffi; Plaisance, Craig; et al (August 2024, Journal of The Electrochemical Society)

   In this study Cu, Sn, and bimetallic CuSn_xnanoparticles were synthesized and evaluated as electrocatalysts for CO₂reduction using zero gap membrane electrode assemblies. Results show bimetallic electrocatalysts with Sn contents above 10% yield formate as a primary product with Faradaic Efficiencies near 70% at 350 mA cm⁻². Cu-Sn_xelectrocatalysts with less than 10% Sn yield CO at current densities below 350 mA cm⁻²and relatively lower cell potentials. When the low-Sn content bimetallic electrocatalysts were evaluated in alkaline anolytes at 350 mA cm⁻², ethanol was recorded as the primary product (FE = 48.5% at E_cell≥ 3.0 V). We propose enhanced C₂activity and selectivity originate from Cu dimers adjacent to Sn atoms for bimetallic electrocatalyst with low-Sn content. The C₂active sites are lost when the surface Sn content exceeds 25%–38%. 

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4. Electrocatalytic Performance of M ₅ X ₄ MXenes for Hydrogen Evolution Reaction

   https://doi.org/10.1002/smll.202503947  

   Devi, Pooja; Downes, Marley; Pahra, Swapna; Ippolito, Stefano; Wang, Ruocun John; Gogotsi, Yury (July 2025, Small)

   Abstract M₅X₄MXenes, a subclass of 2D transition metal carbides, have attracted attention as the thickest 2D material synthesized. Early studies show their promising electrocatalytic activity but overlooked how metal composition and interlayer spacing affect hydrogen evolution reaction (HER). To address this gap, three M₅X₄MXenes, Mo₄VC₄, (TiTa)₅C₄, and (TiNb)₅C₄, are systematically studied and their interlayer spacing and composition modulated through ion exchange with tetramethyl ammonium (TMA⁺vs. Li⁺), providing new insights into their HER activity. These findings reveal that TMA⁺‐intercalated Mo₄VC₄exhibits superior HER activity, achieving areal and gravimetric overpotentials of 172 and 90 mV, respectively, due to its composition (presence of Mo) and expanded interlayer spacing that enhances proton accessibility. The Li⁺exchange increases the overpotential to 212 and 131 mV at 10 mA areal and gravimetric current density, respectively, as reduced interlayer spacing restricts access to active Mo sites. In contrast, (TiNb)₅C₄and (TiTa)₅C₄display higher overpotentials, making them more suitable for supercapacitor or aqueous battery applications due to the wider electrochemical window. This study provides critical insights into the interplay between metal composition and interlayer engineering in M₅X₄MXenes, establishing TMA‐Mo₄VC₄as a promising candidate for sustainable hydrogen production. 

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5. African Plant Functional Type Identification from n-Alkane Chain Lengths via Non-Linear Methods

   Tweedy, Ruth R; Shi, Sarah C; Uno, Kevin T (December 2023, AGU abstracts)

   Reconstructions of eastern African vegetation and climate are critical for understanding primate and large mammal evolution in the Neogene. Insight into past ecological conditions can be gleaned from lipid biomarkers preserved in sedimentary archives, providing evidence for the role of habitats (e.g. open vs. closed vegetation) on evolutionary trait selection. A common paleoecological proxy is the 𝛿¹³C of n-alkanes, which integrates the distinct isotopic signatures of C3 and C4 vegetation. In typical modern tropical ecosystems, “woody” vegetation uses C3 photosynthesis while “grassy” vegetation uses C4 photosynthesis. Under these conditions, mixing models can then estimate the fraction of woody cover of a landscape. While the use of photosynthetic pathways to infer plant functional type (PFT) is powerful, this paradigm does not hold prior to the rise of C4 grasses at 10 Ma, leaving a gap in understanding of ecosystem structure in the early-mid Miocene. To address this issue, we investigate whether n-alkane chain length distributions (rather than 𝛿¹³C) hold information about plant functional type independent of photosynthetic pathway. Here, we present n-alkane chain length data from over 800 modern plant samples, representing a variety of different photosynthetic pathways, growth forms, habitats, and locations. This dataset comprises a significant literature review component, as well as over 400 new distributions generated in this study. We build upon our previous work using PCA and turn to non-linear methods – including both supervised neural network classifiers and unsupervised dimensionality reduction – to determine the potential of n-alkane distributions for PFT identification. Successful differentiation between woody and grassy PFTs using modern plant n-alkane chain lengths will provide a foundation for applying this tool to the geologic record. Our method will compliment well-established isotopic measurement practices while offering the novel ability to reconstruct vegetation structure in pure C3 ecosystems. This represents a particularly powerful tool for understanding ecological history prior to the rise of C4 grasses. 

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