The linear oxo species $\mathrm{Am}{\mathrm{O}}_2^{+}$ and $\mathrm{Am}{\mathrm{O}}_2^{2+}$ for Am(V) and Am(VI), respectively. The charge changes by one on a single-electron redox step.

A thin, extended epithelial cell contributing to the gas-exchange surface. Flattening and molecular differentiation should be measured separately.

An alveolar epithelial cell with secretory functions including surfactant production and context-dependent progenitor activity.

The oxide with formula $\mathrm{A}{\mathrm{l}}_2{\mathrm{O}}_3$. Crystal structure, porosity and surface chemistry distinguish its different material forms.

The generation developing from a zygote and producing spores through meiosis. In the usual land-plant cycle it is diploid. Its nutritional independence and stature differ markedly between bryophytes and vascular plants.

In a semiclassical escape model, an alpha-particle assault frequency is the interior rate scale multiplying the barrier transmission probability. Confinement alone gives $p\sim \hslash /L$ and hence $\nu \sim \hslash /(m_{\alpha }{L}^2)$ up to geometric factors. Counting encounters with either wall differs by a factor of two from returns to one wall. A stationary bound wavefunction does not itself follow a classical collisional trajectory.

The alpha preformation probability is a model-dependent nuclear-structure factor multiplying an interior assault frequency and barrier transmission probability in an alpha-decay rate estimate. It accounts for the availability of an alpha-like cluster at the matching surface. It is not fixed by the exterior Coulomb tunnelling exponent alone.

An aluminium scandium alloy contains scandium added to aluminium, often in a relatively small proportion. Scandium-containing precipitates and changes in grain structure can influence strength and stability.

The strengthening effect depends on microstructure and processing, not simply on adding the masses of two pure metals. It provides an example of how a minor alloying element can strongly alter dislocation motion and grain evolution.

Heat treatment that develops a fine dispersion of a new solid phase in an alloy, impeding dislocation motion. It is distinct from precipitation from a liquid chemical solution. A solid solution may first be formed at high temperature, quenched to retain supersaturation, and then aged to promote solid-state precipitation.

Preferential occupation of distinct crystal sublattices by different chemical elements. Favourable unlike-neighbour bonding can stabilize a periodic alloy arrangement despite its lower configurational entropy than a random alloy.

Enrichment of one component at a material surface relative to its bulk composition. Surface free energies, adsorbates, elastic strain and the energetic cost of changing bulk bonding jointly determine equilibrium enrichment.

An alloy based on zirconium. Low neutron absorption and corrosion behaviour motivate nuclear fuel cladding applications; irradiation growth, creep and hydrogen uptake remain constraints.

An alloy developed to sustain mechanical load at high temperatures while resisting creep and environmental attack.

A coordinated aryne. Strong metal-to-aryne electron transfer can make a dianionic metallacyclopropene description more useful than an unreduced neutral alkyne description.

A microalga is a microscopic algal organism. Eukaryotic microalgae and cyanobacteria have different compartment architectures, so their electron-export mechanisms cannot be assumed identical.

Chromera velia is a photosynthetic alveolate closely related to apicomplexan lineages. Comparative evidence from it helps reconstruct photosynthetic ancestry without assuming that a modern parasite itself photosynthesizes.