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There is a critical need to generate environmentally relevant microplastics (MPs) and nanoplastics (NPs) to better investigate their behavior in laboratory settings. Environmental MPs are heterogenous in size and shape, unlike monodisperse and uniform microspheres commonly used as surrogates. Cryogenic grinding, or cryomilling, was successfully utilized to transform polystyrene (PS) bulk material into heterogenous micro and nano fragments. Fourier-Transform Infrared (FTIR) spectroscopy confirmed that this approach did not alter polymer surface chemistry. The number of milling cycles (time of milling) and frequency of grinding (intensity of milling) were varied to investigate the role cryomilling parameters had on generated MP characteristics. The resulting particle size distributions of cryomilled samples were measured and compared. Coulter Counter and Nanoparticle Tracking Analysis (NTA) were used to measure the particle size distributions at the micro and nanoparticle size ranges, respectively. Microspheres were used to determine what camera settings yielded more accurate sizing and to reduce bias in the NTA analysis. Increasing milling cycles generally increased the number of smaller particles. The evolution of the measured size distributions indicated that small nanosized fragments broke off from larger MPs during cryomilling, steadily eroding larger MP fragments. The number of milling cycles was observed to more consistently impact the size distributions of fragments compared to the frequency of milling. This study offers both analysis of the cryomilling process and recommendations for generating more realistic PS MP/NPs for examining environmental fate and effects.

The Late Triassic Dockum Group in northwestern Texas preserves a rich diversity of pseudosuchian taxa, particularly of aetosaurs. In this contribution, we presentGarzapelta muellerigen. et sp. nov., a new aetosaur from the Late Triassic middle Cooper Canyon Formation (latest Adamanian–earliest Revueltian teilzones) in Garza County, Texas, based on an associated specimen that preserves a significant portion of its dorsal carapace. The carapace ofG.muelleriexhibits a striking degree of similarity between that of the paratypothoracinRioarribasuchus chamaensisand desmatosuchins. We quantitatively assessed the relationships ofG.muelleriusing several iterations of the matrix. Scoring the paramedian and lateral osteoderms ofG.muelleriindependently results in conflicting topologies. Thus, it is evident that our current matrix is limited in its ability to discern the convergence within this new taxon and that our current character lists are not fully accounting for the morphological disparity of the aetosaurian carapace. Qualitative comparisons suggest thatG.muelleriis aRioarribasuchus‐like paratypothoracin with lateral osteoderms that are convergent with those of desmatosuchins. Although the shape of the dorsal eminence, and the presence of a dorsal flange that is rectangular and proportionately longer than the lateral flange are desmatosuchin‐like features ofG.muelleri, the taxon does not exhibit the articulation style between the paramedian and lateral osteoderms which diagnose the Desmatosuchini (i.e., a rigid interlocking contact, and an anteromedial edge of the lateral osteoderm that overlaps the adjacent paramedian osteoderm).

We analyzed spectral cubes of Callisto’s leading and trailing hemispheres, collected with the NIRSpec Integrated Field Unit (G395H) on the James Webb Space Telescope. These spatially resolved data show strong 4.25μm absorption bands resulting from solid-state¹²CO₂, with the strongest spectral features at low latitudes near the center of its trailing hemisphere, consistent with radiolytic production spurred by magnetospheric plasma interacting with native H₂O mixed with carbonaceous compounds. We detected CO₂rovibrational emission lines between 4.2 and 4.3μm over both hemispheres, confirming the global presence of CO₂gas in Callisto’s tenuous atmosphere. These results represent the first detection of CO₂gas over Callisto’s trailing side. The distribution of CO₂gas is offset from the subsolar region on either hemisphere, suggesting that sputtering, radiolysis, and geologic processes help sustain Callisto’s atmosphere. We detected a 4.38μm absorption band that likely results from solid-state¹³CO₂. A prominent 4.57μm absorption band that might result from CN-bearing organics is present and significantly stronger on Callisto’s leading hemisphere, unlike¹²CO₂, suggesting these two spectral features are spatially antiassociated. The distribution of the 4.57μm band is more consistent with a native origin and/or accumulation of dust from Jupiter’s irregular satellites. Other, more subtle absorption features could result from CH-bearing organics, CO, carbonyl sulfide, and Na-bearing minerals. These results highlight the need for preparatory laboratory work and improved surface–atmosphere interaction models to better understand carbon chemistry on the icy Galilean moons before the arrival of NASA’s Europa Clipper and ESA’s JUICE spacecraft.

While technologies for multiplexed imaging have provided an unprecedented understanding of tissue composition in health and disease, interpreting this data remains a significant computational challenge. To understand the spatial organization of tissue and how it relates to disease processes, imaging studies typically focus on cell-level phenotypes. However, images can capture biologically important objects that are outside of cells, such as the extracellular matrix. Here, we describe a pipeline, Pixie, that achieves robust and quantitative annotation of pixel-level features using unsupervised clustering and show its application across a variety of biological contexts and multiplexed imaging platforms. Furthermore, current cell phenotyping strategies that rely on unsupervised clustering can be labor intensive and require large amounts of manual cluster adjustments. We demonstrate how pixel clusters that lie within cells can be used to improve cell annotations. We comprehensively evaluate pre-processing steps and parameter choices to optimize clustering performance and quantify the reproducibility of our method. Importantly, Pixie is open source and easily customizable through a user-friendly interface.

We use Atacama Large Millimeter Array (ALMA) measurements of 870μm thermal emission from a sample of midsized (15–40 km diameter) Jupiter Trojan asteroids to search for high-albedo objects in this population. We calculate the diameters and albedos of each object using a thermal model which also incorporates contemporaneous Zwicky Transient Facility photometry to accurately measure the absolute magnitude at the time of the ALMA observation. We find that while many albedos are lower than reported from WISE, several small Trojans have high albedos independently measured both from ALMA and from WISE. The number of these high-albedo objects is approximately consistent with expectations of the number of objects that recently have undergone large-scale impacts, suggesting that the interiors of freshly-crated Jupiter Trojans could contain high-albedo materials such as ices.