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1. Nucleation-assisted microthermometry: A novel application to fluid inclusions in halite

   https://doi.org/10.1016/j.chemgeo.2024.122318  

   Arnuk, William D; Guillerm, Emmanuel; Lowenstein, Tim K; Krüger, Yves; Olson, Kristian J; Lensky, Nadav G; Brauer, Achim (November 2024, Chemical Geology)

   Halite deposits have long been utilized for interrogating past climate conditions. Microthermometry on halite fluid inclusions has been used to determine ancient water temperatures. One notable obstacle in performing microthermometric measurements, however, is the lack of a vapor bubble in the single-phase liquid inclusions at room temperature. (Pseudo-) isochoric cooling of the inclusions to high negative pressures, far below the homogenization temperature, has commonly been needed to provoke spontaneous vapor bubble nucleation in the liquid. High internal tensile stress in soft host minerals like halite, however, may induce plastic deformation of the inclusion walls, resulting in a wide scatter of measured homogenization temperatures. Nucleation-assisted (NA) microthermometry, in contrast, employs single ultra-short laser pulses provided by a femtosecond laser to stimulate vapor bubble nucleation in metastable liquid inclusions slightly below the expected homogenization temperature. This technique allows for repeated vapor bubble nucleation in selected fluid inclusions without affecting the volumetric properties of the inclusions, and yields highly precise and accurate homogenization temperatures. In this study, we apply, for the first time, NA microthermometry to fluid inclusions in halite and we evaluatethe precision and accuracy of this thermometer utilizing (i) synthetic halite crystals precipitated under controlled laboratory conditions, (ii) modern natural halite that precipitated in the 1980s in the Dead Sea, and (iii) Late Pleistocene halite samples from a sediment core from Death Valley, CA. Our results demonstrate an unprecedented accuracy and precision of the method that provides a new opportunity to reconstruct reliable quantitative temperature records from evaporite archives. 

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2. NUCLEATION-ASSISTED MICROTHERMOMETRY IN HALITE FLUID INCLUSIONS: A NOVEL METHOD FOR OBTAINING PRECISE AND ACCURATE PALEOTEMPERATURES FROM LAKE EVAPORITES

   https://doi.org/10.1130/abs/2023AM-395666  

   Arnuk, William; Guillerm, Emmanuel; Olson, Kristian J; Lowenstein, Tim K; Krüger, Yves (October 2023, Geological Society of America)

   Lacustrine halite deposits have long been utilized for interrogating past climate conditions. In particular, microthermometry performed on fluid inclusions in halite crystals has been used to interpret lake water temperatures from ancient deposits. One notable obstacle in performing microthermometry in halite fluid inclusions is the lack of a vapour bubble in the single-phase liquid brine. Isochoric cooling of the inclusions to high negative pressures far below the homogenization temperature has commonly been used to provoke spontaneous vapor bubble nucleation in the metastable liquid. In a host minerals like halite, however, internal tensile stress may result in plastic deformation of the inclusion walls and typically a wide scatter of measured homogenization temperatures. Nucleation-assisted microthermometry, in contrast, employs single ultra-short laser pulses provided by a femtosecond laser to stimulate vapour bubble nucleation in metastable single-phase liquid inclusions slightly below the expected homogenization temperature. This technique allows for repeated vapour bubble nucleation in fluid inclusions without damaging the inclusion walls, yielding highly precise and accurate paleotemperatures from halite fluid inclusions. Moreover, the highly selective nature of nucleation-assisted microthermometry allows for a higher degree of quality control compared to the previous standard method. In this study, we tested the precision and accuracy of nucleation-assisted microthermometry for use in paleoclimate reconstruction utilizing modern halites precipitated in the laboratory under controlled and monitored conditions, Pleistocene halite samples from Death Valley, and varved halites precipitated in the 1980s in the Dead Sea. 

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3. Lattice Boltzmann Simulation of The Effects of Nanobubble Morphology and Surface Nanofeatures on Superheat-Driven Nucleation and Bubble Growth

   Silva, A; Carey, VP (July 2025, ASME)

   ABSTRACT Bubble nucleation associated with nucleate boiling at superheated surfaces has typically focused on surfaces with features on the order of microns and bubble embryos with comparable interface radii of curvature. For such surfaces the vapor embryo growth or collapse behavior is consistent with surface tension and wetting forces being confined to the contact line region at the surface. In a pure fluid saturating a superheated nanopororus layer, random density fluctuations can lead to the formation of nanoscale bubble embryos. Said fluctuations increase as the liquid is superheated and can lead to macroscopic nucleation. Entrapment of gas when nanostructured surfaces are flooded with liquid can also result in nanoscale bubble embryos in or near the porous layer. For highly wetted nanostructured surfaces, the fluid-to-surface attractive forces are strong over much of a nanobubble embryo, and the critical bubble size that results in spontaneous bubble growth is affected more strongly by surface forces. A Lattice Boltzmann model (LBM) is used to simulate the time evolution behavior of bubble embryos, with radii ranging from 5 to 15 nanometers, close to or within nanoscale interstitial spaces of a nanostructured surface. Single vapor nanobubbles are seeded in surrounding fluid with varying degrees of contact with solid surfaces to simulate smooth or nanostructured surfaces. The effects of varying adsorption coefficient (which dictates contact angle), varying bubble surface radius of curvature, mean distance of wall nanostructures from the embryo, and varying degrees of enclosure of the embryo by surrounding wall structures are explored. The simulation results indicate that the critical radius is largely impacted by the proximity of nanostructures, demonstrating how the fluid-surface forces affect the stability of a vapor embryo. The results suggest that the hydrophilic nature of the surfaces contributes to the suppression in the onset of nucleate boiling which is often seen in hydrophilic nanoporous layers. The implications of these results on convective and nucleate boiling at and within nanostructured surfaces are also discussed. 

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4. Experimental study of interactions between wakes and nucleate boiling in intermittent flow patterns

   https://doi.org/10.1615/TFEC2022.mpp.040970  

   Zhang, X; Rattner, Alexander S. (January 2022, 7th Thermal and Fluids Engineering Conference)

   Extensive research has been conducted to resolve small-scale microlayer and bubble nucleation and departure processes in flow boiling, building on controlled pool boiling studies. Large-scale two-phase flow structures, such as Taylor bubbles, are known to locally modify transport due to their wakes and varying surrounding liquid film thickness. However, the effect of interaction of such large-scale flow processes with bubble nucleation is not yet well characterized. Wakes may drive premature nucleating bubble departure, or conversely, suppress boiling due to boundary layer quenching, significantly affecting overall heat transfer. To explore such phenomena, a two-phase flow boiling visualization facility is developed to collect simultaneous high-speed visualization and infrared (IR) thermal imaging temperature distribution data. The test cell channel is 420 mm long with a 10 mm × 10 mm internal square-cross section. A transparent conductive indium tin oxide (ITO) coated sapphire window serves as a heater and IR interface for measuring the internal wall temperature. The facility is charged with a low boiling point fluid (HFE7000) to reduce uncertainties from heat loss to the laboratory environment. Vertical saturated flow boiling wake-nucleation interaction experiments are performed for varying liquid volume flow rates (0.5 − 1.5 L min-1, laminar-to-turbulent Re) and heat fluxes (0 − 100 kW m-2). Discrete vapor slugs are injected to explore interactions with nucleate boiling processes. By measuring film heater power, surface temperature distributions, and pressures, local instantaneous heat transfer coefficients (HTC) can be obtained. Results will be applied to assess simulations at matched conditions for void fraction, and size statistics of flow structures. 

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5. FEMTOSECOND LASER INDUCED CAVITATION MICROTHERMOMETRY IN PICEANCE CREEK BASIN HALITES

   https://doi.org/10.1130/abs/2022AM-383455  

   Arnuk, William; Lowenstein, Tim; Krüger, Yves (October 2022, Geological Society of America)

   Femtosecond lasers, fired in short pulses, can induce bubble cavitation in single-phase liquid fluid inclusions at temperatures near the inclusion homogenization temperature. By coupling femtosecond laser-induced cavitation with microthermometry, paleotemperatures can be extracted from fluid inclusions in primary halite crystals. This technique minimizes plastic deformation of halite by not subjecting samples to extreme temperatures during vapor bubble nucleation. The resultant homogenization temperatures are precise and reproducible. We applied this technique to Eocene Green River Formation primary bottom-growth halites from the Piceance Creek Basin in Colorado. Samples from the basin-center Savage 24-1 core yield average bottom water temperatures of 27.0 ± 1.3 ºC and 20.1 ± 1.2 ºC for the Upper and Lower Salt intervals, respectively. Average bottom water temperatures from modern perennial hypersaline lakes have been shown to reflect the local mean annual air temperature. Therefore, homogenization temperatures from primary bottom-growth halite fluid inclusions are a proxy for mean annual air temperature. These results agree with regional Early Eocene mean annual air temperature estimate ranges from other mineralogical and biochemical proxies, bolstering the reliability of temperature estimates obtained using this technique. Additionally, the highly selective nature of laser induced cavitation microthermometry allows for a higher degree of quality control compared to standard microthermometry, yielding more reproducible and precise results. 

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