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Foraminifera are unicellular organisms that inhabit the oceans. They play an important role in the global carbon cycle and record valuable paleoclimate information through the uptake of trace elements such as strontium into their calcitic shells. Understanding how foraminifera control their internal fluid composition to make calcite is important for predicting their response to ocean acidification and for reliably interpreting the chemical and isotopic compositions of their shells. Here, we model foraminiferal calcification and strontium partitioning in the benthic foraminiferaCibicides wuellerstorfiandCibicidoides mundulusbased on insights from inorganic calcite experiments. The numerical model reconciles inter-ocean and taxonomic differences in benthic foraminifer strontium partitioning relationships and enables us to reconstruct the composition of the calcifying fluid. We find that strontium partitioning and mineral growth rates of foraminiferal calcite are not strongly affected by changes in external seawater pH (within 7.8–8.1) and dissolved inorganic carbon (DIC, within 2100–2300 μmol/kg) due to a regulated calcite saturation state at the site of shell formation.

Metasurfaces enable precise control over the properties of light and hold promise for commercial applications. However, fabricating visible metasurfaces suitable for high‐volume production is challenging and requires scalable processes. Nanoimprint lithography is a cost‐effective and high‐throughput technique that can meet this scalability requirement. This work presents a mask‐templating nanoimprint lithography process for fabricating metasurfaces with varying fill factors and negligible wavefront aberrations using composite stamps. As a proof‐of‐concept, a 6 mm diameter metalens formed of silicon nitride nano‐posts with a numerical aperture of 0.2 that operates at 550 nm is demonstrated. The nanoimprinted metalens achieves a peak focusing efficiency of (81 ± 1)%, comparable to the control metalens made with electron beam lithography with a focusing efficiency of (89 ± 1)%. Spatially resolved deflection efficiency and wavefront data, which informs design and process optimization, is also presented. These results highlight nanoimprint lithography as a cost‐effective, scalable method for visible metasurface fabrication that has potential for widespread adoption in consumer electronics and imaging systems.

Hydrothermal quartz veins from the Butte deposit display euhedral and mottled cathodoluminescent (CL) textures that reflect the growth and deformation history of quartz crystals. A CL-euhedral texture consists of oscillatory dark-light zonations that record primary precipitation from an aqueous fluid. The origin of a CL-mottled texture, which consists of irregularly distributed dark and light portions, is less clear. Previous work showed that in some veins, CL-euhedral and CL-mottled crystals coexist, but the processes leading to their formation and coexistence were unknown. We find that CL-mottled crystals occur predominantly along the wall rock fracture surface and in vein centers and that CL-euhedral cockscomb quartz protrudes from the mottled layers along the wall rock. We infer that the mottled crystals formed by strain-induced recrystallization that was preferentially accommodated by the rheologically weaker layers of noncockscomb quartz because cockscomb crystals are in hard glide orientations relative to adjacent noncockscomb layers. During strain, crystals in noncockscomb layers that are not initially susceptible to slip can rotate in their deforming matrix until they deform plastically. Some of the CL-mottled crystals exhibit a relict CL-euhedral texture (“ghost bands”) whereby bright bands have been blurred and deformed owing to Ti redistribution facilitated by grain boundary migration. The edges of some CL-euhedral crystals become CL-mottled by localized grain boundary migration along adjacent crystals that do not align perfectly. Throughout the veins, CL-mottled crystals are randomly oriented, indicating that small deviatoric stresses were sufficient to drive recrystallization and mobilization of trace elements. Ti concentrations in CL-mottled crystals (23-47 ppm Ti; mean of 31 ppm) overlap those of CL-euhedral dark growth bands (16-40 ppm Ti; mean of 25 ppm Ti) in neighboring CL-euhedral crystals. Average Ti concentrations in CL-mottled quartz and CL-euhedral dark growth bands correspond to temperature estimates of 600°C (31 ppm Ti; CL-mottled) and 619°C (25 ppm Ti; dark bands), which are in good agreement with previous quartz precipitation temperature estimates based on independent thermobarometers. We conclude that recrystallization resets CL-mottled Ti concentrations close to the equilibrium value for the conditions of deformation and that CL-dark growth bands record near-equilibrium Ti concentrations. Recognition of widespread quartz recrystallization in porphyry Cu deposits underscores the significant role that strain plays in deposit formation. Individual veins host crystals that preserve conditions of primary growth and other crystals that preserve conditions of deformation and thermal overprint. Textural information is key to accurately interpreting trace element data and identifying different stages of vein formation. Our suggestion that CL-dark bands are the best candidates for near-equilibrium growth will aid the interpretation of trace element zoning in other hydrothermal systems.

Despite its increasing application to estimate magma decompression rates for explosive eruptions, the embayment speedometer has long awaited critical experimental evaluation. We present the first experimental results on the fidelity of natural quartz‐hosted embayments in rhyolitic systems as recorders of magma decompression. We conducted two high pressure‐temperature isobaric equilibrium experiments and 13 constant‐rate, continuous isothermal decompression experiments in a cold‐seal pressure vessel where we imposed rates from 0.005 to 0.05 MPa s⁻¹in both H₂O‐saturated and mixed‐volatile (H₂O + CO₂)‐saturated systems. In both equilibrium experiments, we successfully re‐equilibrated embayment melt to new fluid compositions at 780°C and 150 MPa, confirming the ability of embayments to respond to and record changing environmental conditions. Of the 32 glassy embayments recovered, seven met the criteria previously established for successful geospeedometry and were thus analyzed for their volatile (H₂O ± CO₂) concentrations, with each producing a good model fit and recovering close to the imposed decompression rate. In one H₂O‐saturated experiment, modeling H₂O concentration gradients in embayments from three separate crystals resulted in best‐fit decompression rates ranging from 0.012 to 0.021 MPa s⁻¹, in close agreement with the imposed rate (0.015 MPa s⁻¹) and attesting to the reproducibility of the technique. For mixed‐volatile experiments, we found that a slightly variable starting fluid composition (2.4–3.5 wt.% H2O at 150 MPa) resulted in good fits to both H₂O + CO₂profiles. Overall our experiments provide confidence that the embayment is a robust recorder of constant‐rate, continuous decompression, with the model successfully extracting experimental conditions from profiles representing nearly an order of magnitude variation (0.008–0.05 MPa s⁻¹) in decompression rate.

Porous carbon materials have increasingly drawn interest for applications ranging from supercapacitive energy storage to bioengineering. However, a simple and scalable fabrication process of such materials, employing low‐cost chemical compounds without sacrificing morphological and chemical control, remains lacking. Here, a novel, rapid, continuous bottom‐up strategy for synthesizing structurally tunable porous carbon network films on insulating and conductive substrates is reported. By employing rapid thermal annealing (RTA) of a commercial polyacrylonitrile‐based blend, simultaneous phase separation and thermal crosslinking are induced, effectively freezing the structure. Subsequent burning of degradable components generates a porous carbon framework ( ≈ 360 to 700 nm) doped with nitrogen and oxygen atoms. Introducing a boron‐containing reagent in the precursor solution enables boron doping and pore size reduction as small as 20 nm, enhancing materials' performance. The direct fabrication of micro‐supercapacitors on stainless steel substrates is demonstrated, achieving an areal capacitance of 12.7 mF cm⁻²at 50 mV s⁻¹, with ≈98% retention after 10 000 charge/discharge cycles. The benefit of boron doping is further highlighted for wound healing applications. Because RTA is already an established industrial method, this platform directly facilitates the synthesis of functional porous heteroatom‐doped carbon structures using commercial polymers and dopants for various applications.

Most Earth surface carbonates precipitate out of isotopic equilibrium with their host solution, complicating the use of stable isotopes in paleoenvironment reconstructions. Disequilibrium can arise from exchange reactions in the DIC‐H₂O system as well as during crystal growth reactions in the DIC‐CaCO₃system. Existing models account for kinetic isotope effects (KIEs) in these systems separately but the models have yet to be combined in a general framework. Here, an open‐system box model is developed for describing disequilibrium carbon, oxygen, and clumped (Δ₄₇, Δ₄₈, and Δ₄₉) isotope effects in the CaCO₃‐DIC‐H₂O system. The model is used to simulate calcite precipitation experiments in which the fluxes and isotopic compositions of CO₂and CaCO₃were constrained. Using a literature compilation of equilibrium and kinetic fractionation factors, modeledδ¹⁸O and Δ₄₇values of calcite are in good agreement with the experimental data covering a wide range in crystal growth rate and solution pH. This relatively straightforward example provides a foundation for adapting the model to other situations involving CO₂absorption (e.g., corals, foraminifera, and high‐pH travertines) or degassing (e.g., speleothems, low‐pH travertines, and cryogenic carbonates) and/or mixing with other dissolved inorganic carbon sources.