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Abstract Persistent shifts to undesired ecological states, such as shifts from coral to macroalgae, are becoming more common. This highlights the need to understand processes that can help restore affected ecosystems. Herbivory on coral reefs is widely recognized as a key interaction that can keep macroalgae from outcompeting coral. Most attention has been on the role ‘grazing’ herbivores play in preventing the establishment of macroalgae, while less research has focused on the role of ‘browsers’ in extirpating macroalgae. Here we explored patterns, environmental correlates and state shift consequences of spatial co-variation in grazing and browsing functions of herbivorous fishes. Grazing and browsing rates were not highly correlated across 20 lagoon sites in Moorea, French Polynesia, but did cluster into 3 (of 4) combinations of high and low consumption rates (no site had low grazing but high browsing). Consumption rates were not correlated with grazer or browser fish biomass, but both were predicted by specific environmental variables. Experiments revealed that reversibility of a macroalgal state shift was strongly related to spatial variation in browsing intensity. Our findings provide insights and simple diagnostic tools regarding heterogeneity in top-down forcing that influences the vulnerability to and reversibility of shifts to macroalgae on coral reefs. 

Abstract Cuprate high-temperature superconductors (HTSCs) have long stood a promising candidates for various applications due to their high critical temperature ( $T_{\mathrm{c}}$) at ambient pressure. Practical limitations such as low bulk critical current densities ( $J_{\mathrm{c}}^{\mathrm{B}}$), sample inhomogeneities and chemical instability, however, have hindered their applicability. Increasing ${\mathit{T}}_{\mathrm{c}}$, $J_{\mathrm{c}}^{\mathrm{B}}$and the upper critical fields as well as maintaining the chemical stability in cuprates are therefore major goals for these materials science. Here, we characterize the electronic and structural properties of an Ag intercalated ${\mathrm{Bi}}_{1.6}{\mathrm{Pb}}_{0.4}{\mathrm{Sr}}_2{\mathrm{Ca}}_2{\mathrm{Cu}}_3{\mathrm{O}}_{10+\delta }$sample prepared using a novel growth technique. The sample demonstrates enhanced electrical properties that have remained nearly constant over 8 years, while the non-silver Bi-2223 exhibits much degradation in both high- $T_{\mathrm{c}}$fractional phase and superconducting properties. We correlate these bulk electronic properties with structural probes to determine the critical role of Ag in these samples. The enhanced properties of these Ag intercalated cuprates suggest novel synthesis pathways will be key in developing more practical superconductors for applications. 

Abstract Larvae of the caddisfly Arctopsyche grandis BANKS build protective structures and spin silken capture nets in flowing water. Caddisfly H-fibroin, the major protein component of its silk fibers, has a blocky structure with repeating units defined as beginning with a [(SX)nE]m region followed by a G-rich spacer. Previous observation of H-fibroin allelic variation in haploid-resolved individuals led us to investigate allelic variation within two geographically close but separated natural populations of A. grandis. The genomes of 18 individuals were sequenced, and 34 haploid-resolved H-fibroin sequences were extracted. Twenty-four unique alleles were identified in 18 genomes, revealing the dynamic nature of the H-fibroin gene. H-fibroin length variations of up to 25% were tolerated. The major source of the length variations were large-scale deletions and insertions of entire [(SX)nE]m blocks. Small scale indel events were numerous, nonrandomly distributed, and constrained to a few types. One was a 44 residue indel comprising two (SX)nE motifs that split direct tandem repeats in [(SX)nE]m regions, changing m by ±2 without disrupting tertiary structure or block boundaries. The G-rich spacers are of two types, the first distinguished by repeating GLGPH pentapeptides. Indels within this spacer type occur as multiples of the GLGPH pentapeptide. The other category of G-rich spacer was confined to a narrow length distribution. Overall, the results demonstrate the rapid evolution of the caddisfly H-fibroin gene and the wide range of H-fibroin structural polymorphism tolerated in functional capture net silk. At the same time, the limited nature of the indels point to the critical structural features of H-fibroin. 

Embedding plasmonic nanoparticles (NPs) into polymer nanocomposites (PNCs) is a facile method for integrating them into functional devices, whose properties are tunable through varying NP size, shape, and loading. Using anisotropic NPs adds an additional degree of tunability to their orientation order in the PNC, as properties such as conductivity and charge transport can be enhanced in specific directions. In thin films, the film thickness and block copolymer self-assembly can affect the degree of NP orientation, which can be used as a method of control over these properties. However, large-scale control of orientation order in randomly distributed NPs, with both anisotropic NP shapes and heterogeneous shape distributions, remains a chal-lenge. This is partly due to the lack of cost-effective, ensemble-level characterization methods that can independently determine the orientation order and degree of aggre-gation of anisotropic NPs. Here, we model the complex index of refraction of PNCs with plasmonic NP inclusions in the optical frequency domain by using an effective medium approximation. We quantitatively relate the simulated optical birefringence of the medium to the orientation order parameter of plasmonic nanorods and nanodisks in a robust manner insensitive to heterogeneity in simulated NP size and shape. Exper-imentally, we measure this orientation order parameter through the birefringent index of refraction using variable-angle spectroscopic ellipsometry (VASE). We demonstrate that we can independently determine the orientation order and degree of aggregation for various PNCs with gold nanorods and nanosphere inclusions. This facile tech-nique provides a powerful method to broadly measure the average orientation order of anisotropic particles in PNCs, which can be correlated to their functional properties. 

Abstract On tropical reefs, environmental conditions and biological interactions are fundamental drivers of the spatial distribution of corals, which in turn influences community attributes and ecosystem rate processes. Here we focus on a major habitat-providing species of coral, the thicket-forming staghornAcropora pulchra, in Moorea, French Polynesia, to explore environmental attributes that shape its local distribution. At the island scale,A. pulchradecreased in abundance with increasing distance from the shoreline and was inversely related to nitrogen enrichment. To investigate growth-predation risk tradeoffs, we quantified growth and corallivory rates across major abiotic (nutrients, sedimentation) and biotic (corallivorous fish biomass) gradients. At 20 sites divided between fringing reef and mid-lagoon habitats, we quantified colony growth of transplantedA. pulchrafragments (nubbins) that were either exposed or protected from predators after 83 days. Nubbins protected from corallivores grew more in the mid-lagoon than on the fringing reef, whereas mid-lagoon nubbins exposed to predators only achieved 30% of the growth of exposed fringing reef nubbins. These findings suggest that a growth-predation risk tradeoff exists forA. pulchra, with predation a major constraint on the local distribution ofA. pulchrathickets that hinders the ability of staghorn to proliferate further offshore from the fringing reef. 

Abstract Exciton‐polaritons in organic microcavities are applied in devices including lasers, light‐emitting devices, and photodetectors, as well as in structures capable of tuning exciton kinetics and energy transfer. To enable a broader tailoring of polariton properties, it is important to develop means to better control molecular orientation and tune the intensity of the exciton–photon interaction. Vapor‐processed, glassy organic thin films are previously shown to have tunable molecular orientation as evidenced by phenomena including birefringence and transition dipole moment (TDM) alignment. Here, this tunability in TDM orientation with thin film processing conditions is exploited to continuously vary the interaction between the exciton and confined cavity photon mode. By embedding a thin film of 4,4′‐bis[(N‐carbazole)styryl]biphenyl (BSB‐Cz) in a metal‐reflector microcavity, ultrastrong coupling and hybridization of multiple electronic transitions of BSB‐Cz are demonstrated with a common cavity mode. Increasing the temperature during BSB‐Cz deposition tunes the TDM orientation from predominantly in‐plane to random to slightly vertical. This leads to a corresponding ≈30% variation in the associated Rabi splitting, consistent with theoretical predictions. This work demonstrates a means to continuously tune coupling strength from a materials perspective while also providing a handle to tune orientation disorder in thin film. 

 

The search for high-temperature superconductivity among pressure-stabilized hydrides has received great interest since theory-directed clathrate hydrides, such as CaH6, YH6, YH9, and LaH10, were synthesized and shown to exhibit a superconducting critical temperature (Tc) above 200 K. However, further tuning the superconductivity and stability of these prominent hydrides to enhance their applicability remains a significant challenge. Here, we take the sodalite-like clathrate prototype MH6 (M = Ca, Y, etc.) as an example to investigate the stability and superconductivity of multicomponent metal hydrides containing four different metal atoms for each structure. High-throughput simulations of 1820 ABCDH24 quinary hydrides with initial symmetry of F4" 3m, where A, B, C, and D represent different metal atoms were performed. The calculations reveal 119 structures that are dynamically stable at 300 GPa and 67 structures exhibit superconductivity exceeding 200 K, and 20 are found to have Tcs above 260 K. Notable among these quinary alloy hydrides, (Na,Zr,Mg,Hf)H6 is predicted to have a Tc approaching room temperature at 250 GPa. Both configurational and vibrational entropy play important roles in stabilizing these alloy structures. (Na,Y,Zr,Hf)H6, (Mg,Zr,Sc,Y)H6, and (Mg,Hf,Ca,Zr)H6 were computed to be thermodynamically stable, making them promising candidates for experimental synthesis. These quinary superconducting hydrides may facilitate realization of very high-temperature superconductors that are stable over a broader range of conditions than those found for binary or ternary systems.