An official website of the United States government
Oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) are three critical reactions for energy-related applications, such as water electrolyzers and metal-air batteries. Graphene-supported single-atom catalysts (SACs) have been widely explored; however, either experiments or density functional theory (DFT) computations cannot screen catalysts at high speed. Herein, based on DFT computations of 104 graphene-supported SACs (M@C3, M@C4, M@pyridine-N4, and M@pyrrole-N4), we built up machine learning (ML) models to describe the underlying pattern of easily obtainable physical properties and limiting potentials (errors = 0.013/0.005/0.020 V for ORR/OER/HER, respectively), and employed these models to predict the catalysis performance of 260 other graphene-supported SACs containing metal-NxCy active sites (M@NxCy). We recomputed the top catalysts recommended by ML towards ORR/OER/HER by DFT, which confirmed the reliability of our ML model, and identified two OER catalysts (Ir@pyridine-N3C1 and Ir@pyridine-N2C2) outperforming noble metal oxides, RuO2 and IrO2. The ML models quantitatively unveiled the significance of various descriptors and fast narrowed down the potential list of graphene-supported single-atom catalysts. This approach can be easily used to screen and design other SACs, and significantly accelerate the catalyst design for many other important reactions.
more »
« less
Air sacs are a key adaptive trait of the insect respiratory system
ABSTRACT Air sacs are a well-known aspect of insect tracheal systems, but have received little research attention. In this Commentary, we suggest that the study of the distribution and function of air sacs in tracheate arthropods can provide insights of broad significance. We provide preliminary phylogenetic evidence that the developmental pathways for creation of air sacs are broadly conserved throughout the arthropods, and that possession of air sacs is strongly associated with a few traits, including the capacity for powerful flight, large body or appendage size and buoyancy control. We also discuss how tracheal compression can serve as an additional mechanism for achieving advection in tracheal systems. Together, these patterns suggest that the possession of air sacs has both benefits and costs that remain poorly understood. New technologies for visualization and functional analysis of tracheal systems provide exciting approaches for investigations that will be of broad significance for understanding invertebrate evolution.
more »
« less
- Award ID(s):
- 2014181
- PAR ID:
- 10628134
- Publisher / Repository:
- Company of Biologists
- Date Published:
- Journal Name:
- Journal of Experimental Biology
- Volume:
- 226
- Issue:
- 10
- ISSN:
- 0022-0949
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
-
Abstract Using odors to find food and mates is one of the most ancient and highly conserved behaviors. Arthropods from flies to moths to crabs use broadly similar strategies to navigate toward odor sources—such as integrating flow information with odor information, comparing odor concentration across sensors, and integrating odor information over time. Because arthropods share many homologous brain structures—antennal lobes for processing olfactory information, mechanosensors for processing flow, mushroom bodies (or hemi-ellipsoid bodies) for associative learning, and central complexes for navigation, it is likely that these closely related behaviors are mediated by conserved neural circuits. However, differences in the types of odors they seek, the physics of odor dispersal, and the physics of locomotion in water, air, and on substrates mean that these circuits must have adapted to generate a wide diversity of odor-seeking behaviors. In this review, we discuss common strategies and specializations observed in olfactory navigation behavior across arthropods, and review our current knowledge about the neural circuits subserving this behavior. We propose that a comparative study of arthropod nervous systems may provide insight into how a set of basic circuit structures has diversified to generate behavior adapted to different environments.more » « less
-
Abstract Spiders are unique in having a dual respiratory system with book lungs and tracheae, and most araneomorph spiders breathe simultaneously via book lungs and tracheae, or tracheae alone. The respiratory organs of spiders are diverse but relatively conserved within families. The small araneoid spiders of the symphytognathoid clade exhibit a remarkably high diversity of respiratory organs and arrangements, unparalleled by any other group of ecribellate orb weavers. In the present study, we explore and review the diversity of symphytognathoid respiratory organs. Using a phylogenetic comparative approach, we reconstruct the evolution of the respiratory system of symphytognathoids based on the most comprehensive phylogenetic frameworks to date. There are no less than 22 different respiratory system configurations in symphytognathoids. The phylogenetic reconstructions suggest that the anterior tracheal system evolved from fully developed book lungs and, conversely, reduced book lungs have originated independently at least twice from its homologous tracheal conformation. Our hypothesis suggests that structurally similar book lungs might have originated through different processes of tracheal transformation in different families. In symphytognathoids, the posterior tracheal system has either evolved into a highly branched and complex system or it is completely lost. No evident morphological or behavioral features satisfactorily explains the exceptional variation of the symphytognathoid respiratory organs.more » « less
-
Abstract Euthycarcinoid arthropods (Cambrian–Triassic) were likely the first animals to transition from oceanic to freshwater and emergent environments. Although their basic bauplan is well known, they have a poor fossil record because their non-sclerotized exoskeleton was rarely preserved. Euthycarcinoids’ unusual morphology (varying numbers of body segments, seemingly dichotomous possession of either mandibles or a labrum, specialized or generalized limbs, and possession by some euthycarcinoid species of sternal pores—structures possibly analogous to coxal vesicles in myriapods) contribute to uncertainty regarding their relationship to other arthropod groups; while their poor fossil record masks the evolutionary transitions within and between the separate realms they inhabited (marine, freshwater, emergent). A new euthycarcinoid from a Permian polar proglacial lake is described herein that is morphologically unlike all other euthycarcinoids, and interpreted as being well adapted for a nekton-benthic lifestyle. Antarcticarcinus pagoda n. gen. n. sp. possesses a pair of large wing-like processes that project laterally from the preabdominal dorsal exoskeleton. A trace fossil from the overlying Mackellar Formation, cf. Orbiculichnus , which was previously interpreted as having been produced by insects taking off or landing on wet sediments, is reinterpreted herein as being produced by A . pagoda n. gen. n. sp. due to the high degree of morphological similarity between traces and body fossils. This occurrence indicates that euthycarcinoids were able to adapt to life in temperate freshwater environments, while possible subaerial adaptations hint at an ability to breathe air. Indeed, if euthycarcinoids could breathe air, Cambrian terrestrial forays and rapid transition (by the Ordovician) into freshwater environments might be explained.more » « less
-
BackgroundThe trachea, a vital conduit in the lower airway system, can be affected by various disorders, such as tracheal neoplasms and tracheoesophageal fistulas, that often necessitate reconstruction. While short-segment defects can sometimes be addressed with end-to-end anastomosis, larger defects require tracheal reconstruction, a complex procedure with no universally successful replacement strategy. Tissue engineering offers a promising solution for tracheal repair, particularly focusing on regenerating its epithelium, which plays a critical role in protecting the respiratory system and facilitating mucociliary clearance. However, replicating the complex structure and functionality of the tracheal epithelium remains a significant challenge, with key hurdles including proper cell differentiation, functional mucociliary clearance, and addressing the relative lack of vascular supply to the trachea.SummaryCurrent tissue engineering approaches, including biomaterial scaffolds, decellularized tissues, and scaffold-free methods, have shown varying levels of success, while in vitro air-liquid interface (ALI) cultures have provided valuable insights into epithelial modeling. Despite these advances, translating these findings into effective in vivo applications remains difficult due to challenges such as immune responses, inadequate integration with host tissue, and limited longterm functionality of engineered constructs. Overcoming these barriers requires further refinement of cell sources, scaffold materials and bioactive factors that promote vascularization and sustained epithelial function.Key MessagesThis review evaluates the current strategies and modeling, biomaterial scaffolds, cells, and bioactive factors used in tracheal epithelium regeneration, as well as the methods employed to assess their success through histological, functional, and molecular analyses. While significant progress has been made, the development of a safe, functional, and clinically viable trachealgraft remains elusive, underscoring the need for continued innovation in airway tissue engineering. Future advancements in biomaterial design, stem cell technology, and bioreactor-based tissue maturation hold promise for addressing challenges.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1242/jeb.245712
