Temporal instability of lake charr phenotypes: Synchronicity of growth rates and morphology linked to environmental variables?

Pathways through which phenotypic variation among individuals arise can be complex. One assumption often made in relation to intraspecific diversity is that the stability or predictability of the environment will interact with expression of the underlying phenotypic variation. To address biological complexity below the species level, we investigated variability across years in morphology and annual growth increments between and within two sympatric lake charr Salvelinus namaycush ecotypes in Rush Lake, USA. A rapid phenotypic shift in body and head shape was found within a decade. The magnitude and direction of the observed phenotypic change were consistent in both ecotypes, which suggests similar pathways caused the variation over time. Over the same time period, annual growth increments declined for both lake charr ecotypes and corresponded with a consistent phenotypic shift of each ecotype. Despite ecotype-specific annual growth changes in response to winter conditions, the observed annual growth shift for both ecotypes was linked, to some degree, with variation in the environment. Particularly, a declining trend in regional cloud cover was associated with an increase of early-stage (ages 1-3) annual growth for lake charr of Rush Lake. Underlying mechanisms causing changes in growth rates and constrained morphological modulation are not fully understood. An improved knowledge of the biology hidden within the expression of phenotypic variation promises to clarify our understanding of temporal morphological diversity and instability.

Tunable Supramolecular Nanoarchitectures Constructed by the Complexation of Diphenanthro-24-Crown-8/Cesium(I) with Nickel(II) and Silver(I) Ions

Tunable supramolecular nanoarchitectures have received enormous attention because of their potential in materials fabrication. Herein, a variety of morphologically intriguing nanoarchitectures have been constructed from diphenanthro-24-crown-8 ether (DPC) and metal ions. SEM and TEM showed that the self-assembled nanofibers undergo a Cs^I -induced transformation into regular nanoribbons, and further into nanospheres and nanoparticles by the complexation of Ni^II and Ag^I ions because of the strong ion-dipole interaction. Moreover, the X-ray crystal structure determination and powder X-diffraction data further confirmed that these morphological transformations resulted from the different complexation between DPC and metal ions. This result provides a new strategy for the subtle manipulation of supramolecular assemblies.

Aluminum-Tailored Energy Level and Morphology of Co3- x Alx O4 Porous Nanosheets toward Highly Efficient Electrocatalysts for Water Oxidation

Tuning energy levels plays a crucial role in developing cost-effective, earth-abundant, and highly active oxygen evolution catalysts. However, to date, little attention has been paid to the effect of using heteroatom-occupied lattice sites on the energy level to engineer electrocatalytic activity. In order to explore heteroatom-engineered energy levels of spinel Co₃ O₄ for highly-effective oxygen electrocatalysts, herein Al atoms are directly introduced into the crystal lattice by occupying the Co²⁺ ions in the tetrahedral sites and Co³⁺ ions in the octahedral sites (denoted as Co²⁺ _Td and Co³⁺ _Oh , respectively). Experimental and theoretical simulations demonstrate that Al³⁺ ions substituting Co²⁺ _Td and Co³⁺ _Oh active sites, especially Al³⁺ ions occupying the Co²⁺ _Td sites, optimizes the adsorption, activation, and desorption features of intermediate species during oxygen evolution reaction (OER) processes. As a result, the optimized Co_1.75 Al_1.25 O₄ nanosheet exhibit unprecedented OER activity with an ultralow overpotential of 248 mV to deliver a current of 10 mA cm^-2 , among the best Co-based OER electrocatalysts. This work should not only provide fundamental understanding of the effect of Al-occupied different Co sites in Co_3-x Al_x O₄ composites on OER performance, but also inspire the design of low-cost, earth-abundant, and high-active electrocatalysts toward water oxidation.