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1. Effect of printing orientation on mixed‐mode fracture criterion of additively manufactured acrylonitrile butadiene styrene

   https://doi.org/10.1002/pen.27193  

   Leng, Zhuoyuan; Li, Jun; Chalivendra, Vijaya B (June 2025, Polymer Engineering & Science)

   Abstract This study presents an experimental investigation to examine the mixed‐mode fracture behavior of fused filament fabrication printed acrylonitrile butadiene styrene (ABS). The single‐edge notch bending specimen configuration is employed to perform mixed‐mode fracture experiments. Four distinct printing orientations—90°, 0°, 45°/−45°, and 90°—are investigated. For each orientation, fracture studies are conducted under pure mode‐I loading (symmetric three‐point bending), mixed‐mode I/II, and pure mode‐II loading (asymmetric three‐point bending) to establish a mixed‐mode fracture criterion. The study evaluates the influence of printing orientation on fracture toughness, crack propagation behavior, and the mixed‐mode fracture criterion. Scanning electron microscopy (SEM) is utilized to analyze the fracture surfaces and correlate the observed fracture mechanisms with the measured fracture toughness values. The findings reveal that printing orientation significantly affects both the fracture toughness and the mixed‐mode fracture criterion. Among the orientations studied, the 90° specimens exhibit the highest fracture toughness and superior performance under all mixed‐mode conditions. SEM images of the fracture surfaces across different printing orientations show the formation of smooth shear zones of varying sizes near the crack tip under mixed‐mode and pure mode‐II conditions. These zones suggest an enhanced resistance to crack propagation, with the degree of improvement differing among the orientations. HighlightsMixed‐mode fracture behavior of 3D‐printed acrylonitrile butadiene styrene.Printing orientations have a major influence on mixed‐mode fracture criterion.90° printing orientation has the highest fracture toughness for mode‐mixities.0° printing orientation has the lowest fracture toughness for mode‐mixities.Fracture surface has dominant shear zone for all mode‐mixities except mode‐I. 

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2. Computer Vision Applied to In-Situ Specimen Orientation Adjustment for Quantitative SEM Analysis

   https://doi.org/10.1093/micmic/ozac019  

   Klein, Clay; Li, Chunfei (December 2022, Microscopy and Microanalysis)

   Abstract Quantitative analysis methods based on the usage of a scanning electron microscope (SEM), such as energy-dispersive X-ray spectroscopy, often require specimens to have a flat surface oriented normal to the electron beam. In-situ procedures for putting microscopic flat surfaces into this orientation generally rely on stereoscopic methods that measure the change in surface vector projections when the surface is tilted by some known angle. Although these methods have been used in the past, there is no detailed statistical analysis of the uncertainties involved in such methods, which leaves an uncertainty in how precisely a specimen can be oriented. Here, we present a first principles derivation of a specimen orientation method and apply our method to a flat sample to demonstrate it. Unlike previous works, we develop a computer vision program using the scale-invariant feature transform to automate and expedite the process of making measurements on our SEM images, thus enabling a detailed statistical analysis of the method with a large sample size. We find that our specimen orientation method is able to orient flat surfaces with high precision and can further provide insight into errors involved in the standard SEM rotation and tilt operations. 

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3. From comparative connectomics to large-scale working memory modeling in macaque and marmoset

   https://doi.org/10.1101/2025.03.17.643781  

   Magrou, Loïc; Theodoni, Panagiota; Arnsten, Amy_F T; Rosa, Marcello_G P; Wang, Xiao-Jing (March 2025, bioRxiv)

   Abstract Although macaques and marmosets are both primates of choice for studying the brain mechanisms of cognition, they differ in key aspects of anatomy and behavior. Interestingly, recent connectomic analysis revealed that strong top-down projections from the prefrontal cortex to the posterior parietal cortex, present in macaques and important for executive function, are absent in marmosets. Here, we propose a consensus mapping that bridges the two species’ cortical atlases and allows for direct area-to-area comparison of their connectomes, which are then used to build comparative computational large-scale modeling of the frontoparietal circuit for working memory. We found that the macaque model exhibits resilience against distractors, a prerequisite for normal working memory function. By contrast, the marmoset model is sensitive to distractibility commonly observed behaviorally in this species. Surprisingly, this contrasting trend can be swapped by scaling intrafrontal and frontoparietal connections. Finally, the relevance to primate ethology and evolution is discussed. Graphical Abstract HighlightsConsensus mapping allows for directly comparing macaque and marmoset connectomes.Connectomes and spine counts constrain large-scale models of working memory.The marmoset model is susceptible to distraction, but not the macaque.Our results capture real life difference with regard to distraction. 

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4. Specimen‐tailored ‘lived’ climate reveals precipitation onset and amount best predict specimen phenology, but only weakly predict estimated reproduction across a clade

   https://doi.org/10.1111/nph.70338  

   Bontrager, Megan; Worthy, Samantha J; Leventhal, Laura; Maloof, Julin N; Gremer, Jennifer R; Schmitt, Johanna; Strauss, Sharon Y (June 2025, New Phytologist)

   Summary Herbarium specimens are widely distributed in space and time, thereby capturing diverse conditions. We reconstructed specimen ‘lived’ climate from knowledge of germination cues and collection dates for 14 annual species in theStreptanthus(s.l.) clade (Brassicaceae) to ask: which climate attributes best explain specimen phenological stage and estimated reproduction? Are climate effects on phenology and reproduction evolutionarily conserved?We used climate data geolocated to collection sites to reconstruct the climate experienced by specimens and to ask which aspects of climate best explain specimen reproductive traits. We mapped slopes of climate relationships with these traits on the phylogeny to explore evolutionary constraint and models of evolution.Precipitation amount and onset, more than temperature, best predicted specimen phenology, but weakly predicted reproduction. Earlier rainfall was associated with more phenological advancement, a relationship that showed phylogenetic signal. Few climate predictors explained specimen reproduction. Phenological compensation, interactions with other species, or challenges in estimating total reproduction from specimens may reduce the signal between climate and reproduction.We highlight the value of specimen‐tailored growing season estimates for reconstructing climate, incorporating evolutionary relationships in assessing responses to climate. We propose supplemental collection protocols to increase the utility of specimens for understanding climate impacts. 

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5. Juvenile predation overwhelms nutritional effects on female ungulate fat reserves in a high‐predation system

   https://doi.org/10.1111/1365-2435.70343  

   Bealer, Nicole P; Hebblewhite, Mark; Williams, Sara H; Berg, Jodi E; Martin, Hans W; Merrill, Evelyn H (April 2026, Functional Ecology)

   Abstract Ungulate body fat reserves reflect the nutritional environment, often serving as a useful indicator of bottom‐up resource availability. However, body fat reserves also integrate energetic costs associated with avoiding predation risk and reproductive effort, and it is unknown how bottom‐up and top‐down factors integrate to affect body fat reserves.We used generalized mixed‐effects models to evaluate how bottom‐up, top‐down and intrinsic factors explained variation in winter ingesta‐free body fat (IFBF) of female elk (Cervus canadensis) near Banff National Park, Alberta, Canada from 2015 to 2021.We found two top models were competitive, with calf survival during the first 3–4 months of life and female age included in both models. There was more support for bottom‐up forage effects than indirect predation risk effects. Based on model predictions, females with a calf surviving through the previous summer had 3.6 percentage points (95% CI: 2.4%, 4.9%) lower IFBF the subsequent winter than females without a surviving calf.Because calf survival during the first 3–4 months of life is largely driven by predation in this system, we suggest top‐down effects of predation through calf mortality influenced body fat around nine times more than bottom‐up factors in our study. Under high predation, variation in body fat levels of female ungulates across a population may not reflect only bottom‐up influences on body condition, but also differences in predation. Thus, both bottom‐up and top‐down factors must be considered when assessing the nutritional environment. Read the freePlain Language Summaryfor this article on the Journal blog. 

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