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This paper presents a study on the impact of rigid awns and their deployment on interface friction. Awns are appendages attached to the exterior surface of a geo-system and bio inspired by grass seeds. Awns provide frictional anisotropy and assist the seed in self-embedding into the soil or clinging to animal hair. In geo-systems, like piles, deployable awns can provide frictional anisotropy reducing installation effort and increasing global capacity. In addition, flexible awns can be folded up to enable space saving for transportation. This paper presents the results from a set of interface shear tests in a modified direct shear device. Single rigid awns were tested at various angles, from horizontal, as a pseudo-static simulation of deployment, in loose and dense sand, in both the cranial (towards the head) and caudal (towards the tail direction). It is shown that awns opened at larger angles provide higher interface friction and that shearing in the cranial direction provided more resistance than in the caudal direction. This demonstrates that deployable awns could be used in geosystems to provide friction anisotropy and increase capacity. 

Pine sawflies in the genusNeodiprionRohwer are widely distributed across the Northern Hemisphere and are pests of commercially important conifer trees. While sampling forNeodiprionspecies in eastern North America, two colonies ofNeodiprion warreniRoss were discovered in Tennessee feeding onPinus virginianaMill. These are the first records ofN. warreniin Tennessee and on the hostP. virginiana. Here, we use a combination of larval and adult female morphology to confirm species identification. We also discuss two potential explanations for these observations:N. warreniwas always present in Tennessee and feeding onP. virginianabut, until now, has gone unreported or these new records are attributable to a recent range expansion and host shift. We also discuss potential economic and evolutionary implications of range expansions and host shifts in plant-feeding insect pest species.

 

Barocaloric effects─solid-state thermal changes induced by the application and removal of hydrostatic pressure─offer the potential for energy-efficient heating and cooling without relying on volatile refrigerants. Here, we report that dialkylammonium halides─organic salts featuring bilayers of alkyl chains templated through hydrogen bonds to halide anions─display large, reversible, and tunable barocaloric effects near ambient temperature. The conformational flexibility and soft nature of the weakly confined hydrocarbons give rise to order–disorder phase transitions in the solid state that are associated with substantial entropy changes (>200 J kg–1 K–1) and high sensitivity to pressure (>24 K kbar–1), the combination of which drives strong barocaloric effects at relatively low pressures. Through high-pressure calorimetry, X-ray diffraction, and Raman spectroscopy, we investigate the structural factors that influence pressure-induced phase transitions of select dialkylammonium halides and evaluate the magnitude and reversibility of their barocaloric effects. Furthermore, we characterize the cyclability of thin-film samples under aggressive conditions (heating rate of 3500 K s–1 and over 11,000 cycles) using nanocalorimetry. Taken together, these results establish dialkylammonium halides as a promising class of pressure-responsive thermal materials. 

Life table response experiments (LTREs) decompose differences in population growth rate between environments into separate contributions from each underlying demographic rate. However, most LTRE analyses make the unrealistic assumption that the relationships between demographic rates and environmental drivers are linear and independent, which may result in diminished accuracy when these assumptions are violated. We extend regression LTREs to incorporate nonlinear (second‐order) terms and compare the accuracy of both approaches for three previously published demographic datasets. We show that the second‐order approach equals or outperforms the linear approach for all three case studies, even when all of the underlying vital rate functions are linear. Nonlinear vital rate responses to driver changes contributed most to population growth rate responses, but life history changes also made substantial contributions. Our results suggest that moving from linear to second‐order LTRE analyses could improve our understanding of population responses to changing environments.

 

Hundreds of studies have explored student evolution acceptance because evolution is a core concept of biology that many undergraduate biology students struggle to accept. However, this construct of “evolution acceptance” has been defined and measured in various ways, which has led to inconsistencies across studies and difficulties in comparing results from different studies. Many studies and essays have offered evaluations and perspectives of evolution acceptance instruments, but publications with a focus on consensus building across research teams is still needed. Further, little attention has been paid to how evolution acceptance instruments may be interpreted differently by students with varied religious backgrounds. Funded by a Research Coordination Network in Undergraduate Biology Education grant from the National Science Foundation, we gathered 16 experts from different disciplinary and religious backgrounds to review current evolution acceptance instruments and create a guide to the strengths and weaknesses of these instruments, including appropriate contexts for using these instruments and their potential weaknesses with different religious populations. Finally, in an attempt to move the field forward, we articulated a consensus definition of evolution acceptance that can be used to guide future instrument development.

 

Abstract New methods for the synthesis of 1,3-diaryltriazenes and azo dyes from aryl amines are reported. Both methods involve the formation of aryl diazonium intermediates via the transnitrosation of aryl amines with N-nitrososulfonamides. Each two-step transformation may be performed in one reaction vessel at room temperature with no precautions taken to exclude air or moisture. Several triazene and azo dye structures are reported here for the first time, demonstrating the utility of operating the two-step reaction sequence under mild conditions. 

Workbench-size particle accelerators, enabled by Nb₃Sn-based superconducting radio-frequency (SRF) cavities, hold the potential of driving scientific discovery by offering a widely accessible and affordable source of high-energy electrons and x-rays. Thin-film Nb₃Sn RF superconductors with high quality factors, high operation temperatures, and high-field potentials are critical for these devices. However, surface roughness, non-stoichiometry, and impurities in Nb₃Sn deposited by conventional Sn-vapor diffusion prevent them from reaching their theoretical capabilities. Here we demonstrate a seed-free electrochemical synthesis that pushes the limit of chemical and physical properties in Nb₃Sn. Utilization of electrochemical Sn pre-deposits reduces the roughness of converted Nb₃Sn by five times compared to typical vapor-diffused Nb₃Sn. Quantitative mappings using chemical and atomic probes confirm improved stoichiometry and minimized impurity concentrations in electrochemically synthesized Nb₃Sn. We have successfully applied this Nb₃Sn to the large-scale 1.3 GHz SRF cavity and demonstrated ultra-low BCS surface resistances at multiple operation temperatures, notably lower than vapor-diffused cavities. Our smooth, homogeneous, high-purity Nb₃Sn provides the route toward high efficiency and high fields for SRF applications under helium-free cryogenic operations.