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1. Energy-momentum tensor in Φ**4 theory at one loop

   https://doi.org/10.1103/PhysRevD.111.076001  

   Maynard, Brean (April 2025, Physical Review D)

   The energy-momentum tensor form factors are studied in Φ**4 to one-loop order with particular focus on the D-term, a particle property which has attracted a lot of attention in the recent literature. It is shown that the free Klein-Gordon theory value of D = -1 is reduced to D = − 1/3 even if the Φ**4 interaction is infinitesimally small. A companion work in Φ**3 theory confirms this result which may indicate that it is independent of the type of interaction as long as the scalar theory is renormalizable. Dispersion relations are studied. Various definitions of mean square radii including the mechanical radius are investigated. The findings contribute to a better understanding of the energy momentum tensor properties of particles and their interpretation. 

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2. Microstructure Informed Mechanical Properties and Chemomechanical Degradation of Battery Cathode Particles

   https://doi.org/10.1007/s11340-025-01222-w  

   Han, J; Ghosh, R; Lin, F; Zhao, K (August 2025, Experimental Mechanics)

   Abstract BackgroundMechanical degradation of electrodes driven by electrochemical reactions limits battery performance and longevity. While various microstructures of LiNi_xMn_yCo_zO₂(NMC) cathodes have been developed, their comparative mechanical properties and chemomechanical degradation are unknown. ObjectiveThis study measures the mechanical properties of NMC cathode particles of three different microstructures: gravel-type NMC of large grains, gravel NMC of small grains, and rod-shaped NMC. Damage evolution in the NMC particles is simulated using finite element modeling. MethodsWe use flat punch indentation to measure the particle strength, contact modulus, and fracture energy of NMC particles of different microstructures. We also assess the effect of voids on the mechanical properties and damage generation in NMC particles upon cycles. ResultsThe particle strength dictated by grain boundaries is measured to be ~ 200 MPa in the three NMC microstructures. The contact modulus changes nonlinearly during mechanical load. The fracture energy of gravel NMC particles is ~ 0.5 J/m². The presence of voids compromises the mechanical properties of NMC particles, but it helps delocalize stress within the particles and reduces damage generation upon electrochemical cycles. ConclusionsThe combined experiments and modeling provide a comprehensive analysis of the mechanical behaviors and their implications on chemomechanical degradation of NMC cathode particles of various microstructures. 

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3. Evolution and Morphology of Genitalia in Female Amniotes

   https://doi.org/10.1093/icb/icac115  

   Brennan, Patricia L (July 2022, Integrative And Comparative Biology)

   Abstract Despite their evolutionary and biomedical importance, studies of the morphology and function of female genitalia have continued to lag behind those of male genitalia. While studying female genitalia can be difficult because of their soft, deformable and internal nature, recent advances in imaging, geometric analyses of shape and mechanical testing have been made, allowing for a much greater understanding of the incredible diversity of form and function of female genitalia. Here, we summarize some of these methods, as well as discuss some big questions in the field that are beginning to be examined now, and will continue to benefit from further work, especially a comparative approach. Topics of further research include examination of the morphology of female genitalia in situ, in-depth anatomical work in many more species, studies of the interplay between natural and sexual selection in influencing features of vaginal morphology, how these diverse functions influence the mechanical properties of tissues, and studies of clitoris morphology and function across amniotes. Many other research topics related to female genitalia remain largely unexplored, and we hope that the papers in this issue will continue to inspire further research on female genitalia. 

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4. Triplet Fusion Upconversion for Photocuring 3D‐Printed Particle‐Reinforced Composite Networks

   https://doi.org/10.1002/adma.202207673  

   Wong, Jitkanya; Wei, Shixuan; Meir, Rinat; Sadaba, Naroa; Ballinger, Nathan A.; Harmon, Elizabeth K.; Gao, Xin; Altin‐Yavuzarslan, Gokce; Pozzo, Lilo D.; Campos, Luis M.; et al (January 2023, Advanced Materials)

   High energy photons (λ < 400 nm) are frequently used to initiate free radical polymerizations to form polymer networks, but are only effective for transparent objects. This phenomenon poses a major challenge to additive manufacturing of particle-reinforced composite networks since deep light penetration of short-wavelength photons limits the homogeneous modification of physicochemical and mechanical properties. Herein, the unconventional, yet versatile, multiexciton process of triplet–triplet annihilation upconversion (TTA-UC) is employed for curing opaque hydrogel composites created by direct-ink-write (DIW) 3D printing. TTA-UC converts low energy red light (λmax = 660 nm) for deep penetration into higher-energy blue light to initiate free radical polymerizations within opaque objects. As proof-of-principle, hydrogels containing up to 15 wt.% TiO2 filler particles and doped with TTA-UC chromophores are readily cured with red light, while composites without the chromophores and TiO2 loadings as little as 1–2 wt.% remain uncured. Importantly, this method has wide potential to modify the chemical and mechanical properties of complex DIW 3D-printed composite polymer networks. 

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5. Particle Deformability Enables Control of Interactions between Membrane-Anchored Nanoparticles

   https://doi.org/10.1021/acs.jctc.3c00687  

   Nambiar, Nikhil; Loyd, Zachary A; Abel, Steven M (October 2023, Journal of Chemical Theory and Computation)

   Nanoparticles adsorbed on a membrane can induce deformations of the membrane that give rise to effective interactions between the particles. Previous studies have focused primarily on rigid nanoparticles with fixed shapes. However, DNA origami technology has enabled the creation of deformable nanostructures with controllable shapes and mechanical properties, presenting new opportunities to modulate interactions between particles adsorbed on deformable surfaces. Here we use coarse-grained molecular dynamics simulations to investigate deformable, hinge-like nanostructures anchored to lipid membranes via cholesterol anchors. We characterize deformations of the particles and membrane as a function of the hinge stiffness. Flexible particles adopt open configurations to conform to a flat membrane, whereas stiffer particles induce deformations of the membrane. We further show that particles spontaneously aggregate and that cooperative effects lead to changes in their shape when they are close together. Using umbrella sampling methods, we quantify the effective interaction between two particles and show that stiffer hinge-like particles experience stronger and longer-ranged attraction. Our results demonstrate that interactions between deformable, membrane-anchored nanoparticles can be controlled by modifying mechanical properties of the particles, suggesting new ways to modulate the self-assembly of particles on deformable surfaces. 

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