External Fluid Research Articles

A Reusable Capillary Flow-Driven Microfluidic System for Abscisic Acid Detection Using a Competitive Immunoassay

Point-of-care (PoC) devices offer a promising solution for fast, portable, and easy-to-use diagnostics. These characteristics are particularly relevant in agrifood fields like viticulture where the early detection of plant stresses is crucial to crop yield. Microfluidics, with its low reagent volume requirements, is well-suited for such applications. Self-driven microfluidic devices, which rely on capillary forces for fluid motion, offer an attractive alternative by eliminating the need for external pumps and complex fluid control systems. However, traditional microfluidic prototyping materials like polydimethylsiloxane (PDMS) present challenges due to their hydrophobic nature. This paper presents the development of a reusable, portable, capillary-driven microfluidic platform based on a PDMS-PEG (polyethylene glycol) copolymer designed for the rapid low-cost detection of abscisic acid (ABA), a key biomarker for the onset of ripening of non-climacteric fruits and drought stress in vines. By employing passive fluid transport mechanisms, such as capillary-driven sequential flow, this platform enables precise biological and chemical screenings while maintaining portability and ease of use. A simplified field-ready sample processing method is used to prepare the grapes for analysis.

Stability and agility trade-offs in spring-wing systems.

Flying insects are thought to achieve energy-efficient flapping flight by storing and releasing elastic energy in their muscles, tendons, and thorax. However, 'spring-wing' flight systems consisting of elastic elements coupled to nonlinear, unsteady aerodynamic forces present possible challenges to generating stable and responsive wing motion. The energetic efficiency from resonance in insect flight is tied to the Weis-Fogh number (N), which is the ratio of peak inertial force to aerodynamic force. In this paper, we present experiments and modeling to study how resonance efficiency (which increases withN) influences the control responsiveness and perturbation resistance of flapping wingbeats. In our first experiments, we provide a step change in the input forcing amplitude to a series-elastic spring-wing system and observe the response time of the wing amplitude increase. In our second experiments we provide an external fluid flow directed at the flapping wing and study the perturbed steady-state wing motion. We evaluate both experiments across Weis-Fogh numbers from1<N<10. The results indicate that spring-wing systems designed for maximum energetic efficiency also experience trade-offs in agility and stability as the Weis-Fogh number increases. Our results demonstrate that energetic efficiency and wing maneuverability are in conflict in resonant spring-wing systems, suggesting that mechanical resonance presents tradeoffs in insect flight control and stability.

Effects of variable blowouts on aerodynamic loss reduction performance of compressor bionic blades

Abstract A passive flow control method inspired by blowouts was employed to eliminate flow separation and reduce the losses associated with higher compressor loads. The flow characteristics of a dimple-shaped cascade were investigated by implementing bionic blowout dimples on a blade suction surface and the loss-generation mechanism was analyzed. First, the reliability of the numerical simulation was confirmed via experimental validation. Subsequently, biomimetic principles were applied to arrange dimples on the suction surface of cascade blades, and the effects of several blowouts were analyzed. The analysis revealed that vortices within the dimples induced external fluid into the dimples, thereby increasing the turbulent kinetic energy of the external fluid and improving wall-adjacent flow adherence. The bionic-blowout variant dimples created a ‘rolling bearing’ effect that reduced frictional losses and effectively controlled flow separation. Within a certain blowout range, the bionic blowout variant dimples significantly improved the flow characteristics. At a −6° angle of attack, the total pressure loss of the dimple-structured cascade decreased by 35.85%, and the pressure ratio increased by 2.35%. The bionic blowout-variant dimples on the blade suction surface exhibited a three-dimensional disturbance effect. The induced vortex structures regulated the boundary layer transition and suppressed the formation of laminar separation bubbles, thereby enhancing the flow conditions near the corner region.

Synthetic Jet Actuators for Active Flow Control: A Review

A synthetic jet actuator (SJA) is a fluidic device often consisting of a vibrating diaphragm that alters the volume of a cavity to produce a synthesized jet through an orifice. The cyclic ingestion and expulsion of the working fluid leads to a zero-net mass-flux and the transfer of linear momentum to the working fluid over an actuation cycle, leaving a train of vortex structures propagating away from the orifice. SJAs are a promising technology for flow control applications due to their unique features, such as no external fluid supply or ducting requirements, short response time, low weight, and compactness. Hence, they have been the focus of many research studies over the past few decades. Despite these advantages, implementing an effective control scheme using SJAs is quite challenging due to the large parameter space involving several geometrical and operational variables. This article aims to explain the working mechanism of SJAs and provide a comprehensive review of the effects of SJA design parameters in quiescent conditions and cross-flow.

Cerebrospinal Fluid Leak Prevention in Intradural Spine Surgery: A Long Series Analysis of Closure with Non-Penetrating Titanium Clips

Background/Objectives: Postoperative cerebrospinal fluid (CSF) fistulas remain a significant concern in spinal neurosurgery, particularly following dural closure. The incidence of dural tears during spinal surgery is estimated between 1.6% and 10%. While direct suturing remains the gold standard, it has a failure rate of 5–10%. Various materials and techniques have been used to enhance dural closure. This study aims to assess the effectiveness of non-penetrating titanium clips (AnastoClip®) for dural closure in intradural spinal lesion surgeries. Methods: A prospective analysis was conducted on 272 patients who were operated on for intradural spinal lesions from August 2017 to December 2023. Dural closure was performed using non-penetrating titanium clips with sealant, and, in select cases, autologous grafts. Postoperative care included early mobilization and routine MRI to assess outcomes. A comparative analysis was performed with a cohort of 81 patients treated with traditional sutures. Results: Among the 272 patients, postoperative CSF leaks occurred in 32 cases (11.76%), requiring various management approaches. Thirteen cases required surgical revision, while others resolved with external lumbar drainage or fluid aspiration. Compared to the suture group, which had a fistula rate of 23.46%, the titanium clip group had a significantly lower fistula rate. Logistic regression analysis did not find statistically significant associations between fistula risk and clinical factors. Conclusions: Non-penetrating titanium clips provide an effective alternative to sutures for dural closure, reducing CSF leak rates. They preserve dural integrity, reduce operative time, and avoid imaging artifacts, making them a viable advancement in spinal surgery with outcomes comparable to, or better than, traditional techniques.

Identification of Multiple Thermal Events in High‐Grade Metacarbonate Rocks Using Carbon Isotope Thermometry: An Example From the Sør Rondane Mountains, East Antarctica

ABSTRACTNine metacarbonate layers from the regionally metamorphosed terrane of the Sør Rondane Mountains in the Eastern Dronning Maud Land in East Antarctica were examined in detail for constraining the thermal events using carbon isotope exchange between dolomite/calcite and graphite. Equilibrium carbon isotope fractionation between dolomite and graphite suggested peak metamorphic temperature conditions reaching up to 802°C ± 29°C were estimated at the Balchenfjella locality, where multiple samples from six thick layers of metacarbonate rocks were examined. However, some of the samples exhibit lower carbon isotope fractionation reflecting the possibility of ultrahigh‐temperature metamorphic conditions, which is consistent with recent reports. Furthermore, several metacarbonate rock samples display large variations in δ13CVPDB values for graphite grains, despite dolomite and calcite showing homogeneous carbon and oxygen isotopic composition indicating signatures of retrograde metamorphism and fluid infiltration events. Detailed textural observation suggested alteration of δ13CVPDB values of graphite during retrograde metamorphism might have resulted due to the overgrowth of graphite crystals by the infiltration of low δ13CVPDB‐bearing fluids, the extent of alteration being a direct function of the fluid–rock ratio. Field evidence indicates the presence of carbonate veins cutting across the metacarbonate rocks suggesting that carbon isotope thermometry can also be utilised to understand the effect of external fluid infiltration. At Perlebandet locality the metamorphic temperature conditions were estimated to be around 915°C, whereas those from Tanngarden and Menipa gave lower temperature estimates. Detailed textural analysis of graphite in combination with isotopic composition provided clear evidence for retrograde events. Thus, our results provide tight constraints of peak and post‐peak metamorphic temperature conditions and a regional thermal structure for the Sør Rondane Mountains and further testify the usefulness of carbon isotope thermometry in polymetamorphic terrains.

Lift force on a spherical droplet in a viscous linear shear flow

We study numerically the flow around a spherical droplet set fixed in a linear shear flow with moderate shear rates ( $Sr\leq 0.5$ , $Sr$ being the ratio between the velocity difference across the drop and the relative velocity) over a wide range of external Reynolds numbers ( $0.1&lt;{{Re}}\leq 250$ , ${{Re}}$ based on the slip velocity and the viscosity of the external fluid) and drop-to-fluid viscosity ratios ( $0.01\leq \mu ^\ast \leq 100$ ). The flow structure, the vorticity field and their intrinsic connection with the lift force are analysed. Specifically, the results on lift force are compared with the low- ${{Re}}$ solution derived for droplets of arbitrary $\mu ^\ast$ , as well as prior data at finite ${{Re}}$ available in both the clean-bubble limit ( $\mu ^\ast \to 0$ ) and the solid-sphere limit ( $\mu ^\ast \to \infty$ ). Notably, at ${{Re}}=O(100)$ , the lift force exhibits a non-monotonic transition from $\mu ^\ast \to 0$ to $\mu ^\ast \to \infty$ , peaking at $\mu ^\ast \approx 1$ . This behaviour is related to an internal three-dimensional flow bifurcation also occurring under uniform-flow conditions, which makes the flow to evolve from axisymmetric to biplanar symmetric. This flow bifurcation occurs at low-but-finite $\mu ^\ast$ when the internal Reynolds number ( ${{Re}}^i$ , based on the viscosity of the internal fluid) exceeds approximately 300. In the presence of shear, the corresponding imperfect bifurcation enhances the extensional rate of the flow in the wake. Consequently, the streamwise vortices generated behind the droplet can be more intense compared with those behind a clean bubble. Given the close relation between the lift and these vortices, a droplet with ${{Re}}=O(100)$ and $\mu ^\ast \approx 1$ typically experiences a greater lift force than that in the inviscid limit.

Investigation of Chaotic Flutter Induced by Shock-Boundary-Layer Interactions

In this report, we investigate the onset of chaotic flutter in laminar and turbulent flows over a two-dimensional semi-infinite panel using time-accurate fluid–structure interaction (FSI) simulations of shock–boundary-layer interactions (SBLIs). Results indicate that the critical dynamic pressure and the nature of the panel dynamics strongly depend on the static pressure differential across the shock, the local loading, the viscous and turbulent damping in the flow, and the formation of dynamic flow separation bubbles due to the SBLIs. The structural system undergoes local instability (Hopf bifurcation) when the local loading due to panel deformation overcomes the static pressure differential across the shock. In the absence of external fluid instabilities, the structural oscillations will induce unsteadiness in the flowfield, resulting in low-frequency limit-cycle oscillations. Viscous and turbulent damping in the boundary layer also delays the bifurcation and reduces the amplitude of the oscillations. Sufficiently strong shocks can produce localized flow separations, which drive additional boundary-layer instabilities, resulting in an early bifurcation. In the presence of external fluid instabilities, the behavior of the FSI strongly depends on the nonlinear coupling of their instabilities. Chaotic oscillations are observed when the fluid instabilities are dominant enough to induce structural oscillations with broadband frequencies.

Dispersion Characteristics of Flexural Waves in Vacuo and Submerged Fluid-filled Pipes

Abstract Pipelines are widely recognised as the most efficient and sustainable infrastructure for water transportation in the water management and distribution industries, but their efficiency is often compromised by leaks. In this paper, the low-frequency flexural behaviour is investigated to estimate the dispersion characteristic of free flexural wave propagation in MDPE water pipes. It is investigated under two conditions: an empty and fluid-filled pipe either surrounded by air or by water. An Euler Bernoulli prediction model was developed for these pipe scenarios, and validation experiments were conducted on a 1.8-metre-long pipe. Results showed that the flexural wavenumber is lower in an empty pipe compared to a water filled pipe. This is because the water adds mass, which reduces the wave speed. The behaviour of the flexural waves is also affected by the fluid outside the pipe, where the external fluid adds mass to the pipe wall, causing the wavespeed to decrease. Experimental results are in good agreement with an analytical model at low frequencies but not at higher frequencies, since higher-order bending waves are present in the experiment results.

A Simplified Mathematical Model for Cell Proliferation in a Tissue-Engineering Scaffold.

While the effects of external factors like fluid mechanical forces and scaffold geometry on tissue growth have been extensively studied, the influence of cell behavior-particularly nutrient consumption and depletion within the scaffold-has received less attention. Incorporating such factors into mathematical models allows for a more comprehensive understanding of tissue-engineering processes. This work presents a comprehensive continuum model for cell proliferation within two-dimensional tissue-engineering scaffolds. Through mathematical modeling and asymptotic analysis based on the small aspect ratio of the scaffolds, the study aims to reduce computational burdens and solve mathematical models for tissue growth within porous scaffolds. The model incorporates fluid dynamics of nutrient feed flow, nutrient transport, cell concentration, and tissue growth, considering the evolving scaffold porosity due to cell proliferation, with the crux of the work establishing the ideal pore shape for channels within the tissue-engineering scaffold to obtain the maximum tissue growth. We investigate scaffolds with specific two-dimensional initial porosity profiles, and our results show that scaffolds which are uniformly graded in porosity throughout their depth promote more tissue growth.

Adaptive Bounded Bilinear Control of a Parallel‐Flow Heat Exchanger

ABSTRACTThis work investigates the adaptive constrained control design for a parallel‐flow heat exchanger represented by a system of two coupled linear first‐order hyperbolic partial differential equations (PDEs). This system incorporates structured uncertainty involving unknown in‐domain parameters that characterize neglected dynamics in the heat exchanger model. These parameters may encompass unmodeled heat transfer phenomena, variations in fluid properties, and modeling simplifications. The objective is to regulate the internal fluid outlet temperature to track a desired reference trajectory by adjusting the external fluid velocity. Due to inherent physical constraints, this manipulated variable is upper and lower‐bounded. Accordingly, the control problem is bounded and bilinear. Using the set‐invariance principle and an energy‐like framework, we first develop a bounded state‐feedback controller. Then, since the measurements are considered only at the boundaries, we propose an adaptive boundary observer using a swapping scheme and a recursive least squares identifier. The proposed adaptive observer provides online estimates of the distributed state and the unknown parameters. Next, the state‐feedback controller is associated with the boundary observer and parameter identifier, and the exponential stability of the closed‐loop system is guaranteed using Lyapunov's stability theory. Finally, we provide numerical simulations to demonstrate the efficiency of the proposed control scheme.

A Simple Pump-Free Approach to Generating High-Throughput Microdroplets Using Oscillating Microcone Arrays.

Droplet generation is crucial in various scientific and industrial fields, such as drug delivery, diagnostics, and inkjet printing. While microfluidic platforms enable precise droplet formation, traditional methods often require costly and complex setups, limiting their accessibility. This study introduces a simple, low-cost approach using an off-the-shelf unit and a 3D-printed reservoir. The device, equipped with a driver board, piezo-ring transducer, and a metal sheet with holes, generates oil-in-water (O/W) droplets with an average diameter of 4.62 ± 0.67 µm without external fluid pumps. Its simplicity, cost-effectiveness, and scalability make it highly suitable for both lab-on-chip and industrial applications, demonstrating the feasibility of large-scale uniform droplet production.

Contact metamorphism and dolomitization overprint on Cambrian carbonates from the Ossa-Morena Zone (SW Iberian Massif): implications to Sr-chronology of carbonate rocks

AbstractThe Cambrian Series 2 Carbonate Formation from the Alter do Chão Elvas-Cumbres Mayores unit (Ossa-Morena Zone, SW Iberian Massif) is composed of regionally metamorphosed marbles and marlstones that underwent chlorite zone metamorphism and preserve the primaeval limestone 87Sr/86Sr ratios (0.7083–0.7088). These are consistent with the established Lower Cambrian seawater curve, and therefore used for age constraints in formations lacking fossil contents. The regional mineralogical and Sr-isotopic features of the carbonate rocks are frequently overprinted by the effects of contact metamorphism induced by magmatic bodies emplaced during rift-related and synorogenic events of the Palaeozoic, as well as by post-metamorphic dolomitization processes. The development of calc-silicate minerals due to contact metamorphism is common in the rocks of the Carbonate Formation and apparently results from the interaction of the protolith with fluids of different origin: (i) internally produced fluids released by conductive heating (observed in external contact aureoles) and (ii) external intrusion-expelled fluids that, besides leading to the appearance of distinctive assemblages, also promote an influx of strontium content (observed in roof pendants). Calc-silicate mineralogy varies substantially throughout the region, likely due to the heterogeneous distribution of silicate minerals of the protolith, progression of intrusion-driven fluids, and the irregular effect of thermal gradients. Results suggest that high-grade contact metamorphism (hornblende facies or higher) and dolomitization processes imposed on the Carbonate Formation significantly influence the isotopic signatures of the carbonates, providing limitations in applying Sr-isotopic chronology. Graphical abstract

Internal heating and distribution in electromagnetic powell-Eyring [formula omitted]/glycerin hybridized nanomaterial with radiation and wall slip conditions

The synergistic influences of the hybridization of molybdenum disulfide (MoS2) and graphene oxide (GO) nanoparticles on electromagnetic radiation absorption and augmentation of thermal conductivity coupled with the industrial demand for an enhanced non-Newtonian working fluid spurred this study. Therefore, the study examines the radiative properties and thermal behaviour of hybridized MoS2 and GO nanoparticle systems dispersed in a glycerin Powell-Eyring fluid with wall slip conditions. A theoretical mathematical setup is modelled for the nanoparticle thermophysical characteristics with viscous dissipation and heat generation under the influence of the electromagnetic Riga plate. The model is transformed into an invariant dimensionless form and solved utilizing the pseudo-spectral collocation technique. The effect of fluid rheology, nanoparticle concentration, and fluid-wall slip conditions interface on radiative heat transfer and thermal propagation is investigated. The results reveal momentous augments in radiation absorption and thermal conductivity of about 4.13% to 10.22% due to MoS2 and GO hybridized nanoparticles. Also, it was found that thermal transport is enhanced close to the solid boundary wall slip, leading to an improve heat distribution rate. Hence, this study contributes to the interplay complexity between external stimuli, fluid dynamics, and nanoparticle morphology in thermal systems, offering insights into the advanced materials synthesis, thermal management systems, and optimization and design of nanoparticle fluid enhancement applications.

Involvement of syn–, para– and post–magmatic hydrothermal fluids in the alteration of the Kamthai carbonatite complex (India): Insights from in-situ measured 87Sr/86Sr isotope and trace element composition of calcite

The major-trace element and C-O-Sr isotopic composition of calcite constitute important proxies for reconstructing the magmatic and hydrothermal evolution of carbonatites. This study reports new 87Sr/86Sr isotope data measured in-situ from six textural types of calcite in carbonatite and fenitized phonolites of the Kamthai carbonatite complex in western India. Textural relations, along with major-trace element chemistry, and Sr isotope composition helps to discriminate four types of calcite in carbonatites—magmatic (CalM), partially reequilibrated magmatic (CalPR), and two varieties of secondary (CalSK and CalS). CalM has high concentrations of ƩREE + Y, Sr, Ba and Mn, restricted 87Sr/86Sr (0.70437 ± 0.00005), and lacks Ce or Y anomaly. It crystallized from late-stage brine-melt together with primary carbocernaite after prolonged fractional crystallization of the carbonatite magma. CalPR has identical 87Sr/86Sr (0.70425 ± 0.00024) as CalM, and formed by its partial reequilibration, accompanied by significant loss of REE, and Sr during interaction with synmagmatic fluid. The two secondary varieties of calcite in the carbonatites have overlapping but marginally higher 87Sr/86Sr (CalSK = 0.70469 ± 0.00041; CalS = 0.70478 ± 0.00025) compared to CalM, which indicates that they were altered by syn– to para– magmatic fluids with minor contribution from post-magmatic fluid (e.g., external crust-derived fluid). Both types are highly porous and have low-Z contrast in back scattered electron images, which is the result of expulsion of most of its original Sr and REE budget during fluid-induced reequilibration. Two types of secondary calcite (CalS1 and CalS2) are identified in three veins within fenitized phonolite. These contain the lowest abundance of ΣHREE + Y, Sr, Ba and Mn. One type (CalS2) occurs in calcite-quartz-pyrite veins and is characterized by LREE-depleted REE patterns and igneous-calcite-like 87Sr/86Sr (0.70434 ± 0.00073). It possibly crystallized from evolved late-stage para-magmatic fluids from the carbonatite magma after the brine-melt stage of primary LREE mineralization. The other type of vein calcite (CalS1) is characterized by strong negative Ce (δCe*: ≪0.034) anomalies, which indicates that it crystallized from oxidized fluids from which Ce was removed as Ce (IV). The 87Sr/86Sr of some of these calcites are significantly more radiogenic (0.70768 ± 0.00011) than magmatic calcite. This indicates that post-magmatic fluid played a significant role in their formation. Two component mixing calculations show that up to 40–70 % post-magmatic fluid mixed with syn-magmatic fluid can account for their Sr isotope composition. Magmatic calcite and carbocernaite were the major sources of REE and Sr during secondary redistribution.

Shear stress sensing in C. elegans

Shear stress sensing represents a vital mode of mechanosensation.1 Previous efforts have mainly focused on characterizing how various cell types-for example, vascular endothelial cells-sense shear stress arising from fluid flow within the animal body.1,2 How animals sense shear stress derived from their external environment, however, is not well understood. Here, using C.elegans as a model, we show that external fluid flow triggers behavioral responses in C.elegans, facilitating their navigation of the environment during swimming. Such behavioral responses primarily result from shear stress generated by fluid flow. The sensory neurons AWC, ASH, and ASER are the major shear stress-sensitive neurons, among which AWC shows the most robust response to shear stress and is required for shear stress-induced behavior. Mechanistically, shear stress signals are transduced by G protein signaling in AWC, with cGMP as the second messenger, culminating in the opening of cGMP-sensitive cyclic nucleotide-gated (CNG) channels and neuronal excitation. These studies demonstrate that C.elegans senses and responds to shear stress and characterize the underlying neural and molecular mechanisms. Our work helps establish C.elegans as a genetic model for studying shear stress sensing.

Preparation of zwitterionic polymer and its application for dual-functional inhibition in deepwater drilling

During deep-water drilling operations, due to the conditions with low temperature and high pressure in the wellbore, methane hydrate can be easily formed in the presence of methane and plug the wellbore. In addition, the deep-water sediments are dominated by clay-silty with weak cementation, so well instability may be occurred due to clay hydration. In order to inhibit hydrate formation and clay hydration in deepwater drilling, a zwitterionic polymer AADV was synthesized through quaternary copolymerization of AM/AMPS/DMDAAV/VAC. The hydrate inhibition performance of AADV was evaluated in a high-pressure reactor chamber, and the results showed that AADV can delay the hydrate formation time from 330 min in pure water to 2204 min, indicating an excellent inhibition effect of hydrate formation. Meanwhile, 1 % AADV can significantly reduce the linear swelling rate of the calcium-based bentonite to 3.69 % for 10 h and increase the rolling recovery rate to 94.7 %, suggesting an excellent inhibition effect on clay hydration. The mechanism of dual-functional inhibition of AADV was further analyzed. The zwitterionic group in AADV and the hydrophilic amide group can strongly adsorb the water molecules through a strong hydration effect and the hydrogen bonding effect, respectively, which contributes to destroy the water molecules cage structure, and thus to suppress the hydrate formation. Besides, AADV can effectively obstruct mass transfer of methane molecules by increasing the viscosity of the aqueous phase and absorbing on the hydrate surface, leading to hydrate formation inhibition. For the inhibition of clay hydration, the SEM and XRD results proved that AADC inhibits the clay hydration through the film-forming effect. In addition, the contact angle of Na-Bent/AADC composite reached to 55.68° when the polymer concentration increased to 2 %, suggesting that the hydrophobicity of Na-Bent surface can be enhanced after AADC treatment. AADV can wrap around clay particles and form hydrophobic film through adsorption and intercalation, preventing the intrusion of external fluids and inhibiting clay hydration.

Experimental investigation of hydrogen isotope fractionation during hydration of olivine-hosted melt inclusions: Implications for D/H in Baffin Island picrites

Olivine-hosted melt inclusions are used to investigate the hydrogen isotope compositions (D/H) of Earth's mantle reservoirs. Studies have shown, however, that hydrogen in melt inclusion can equilibrate rapidly in response to changes to the external environment via the diffusion of protons (H+) and deuterons (D+) through the host olivine. Given that protons diffuse faster than deuterons, a kinetic fractionation of hydrogen isotopes is expected to accompany both the hydration and dehydration of melt inclusions. Other volatile species in the melt inclusion may also be affected by changes to the internal pressure and/or oxygen fugacity (fO2). Here we report results from experiments designed to investigate the behaviors of volatiles and hydrogen isotopes during the hydration of olivine-hosted melt inclusions. We show that the concentration of H2O in initially H2O-poor inclusions increases rapidly (up to ∼4 wt.% within 24 h) when the host olivine is in contact with aqueous fluid at 1200 °C and 300 MPa. The extent of hydration is controlled by time, temperature, melt inclusion volume, and H+ diffusion distance. Hydrogen isotopes initially become lighter (i.e., D/H decreases) as hydration proceeds, defining a negative correlation with H2O concentration. This trend reverses with increasing hydration as the inclusions must eventually equilibrate with the external fluid. These experimental results agree well with diffusion calculations carried out using a spherical geometry and a lattice diffusivity of 10–11.2±0.2 m2/s for H+ at 1200 °C. Therefore, anomalously light hydrogen isotopes in olivine-hosted melt inclusions from Baffin Island may not be taken as representative of the composition of the mantle source unless post-entrapment hydration can be excluded as a possibility. An increase in CO2 concentration and a significant drop in sulfur concentration accompany hydration of the melt inclusions in our experiments. The former is consistent with an observed decrease in vapor bubble size and results from a hydration-induced internal pressure increase. The latter is ascribed to the exsolution of molten sulfide from the silicate melt, which might be related to a lower fO2 in the experiments as compared to the starting materials. We find no evidence for exchange of F or Cl between the melt inclusion and external fluid.

High Spatiotemporal Precision Mapping of Optical Nanosensor Array Using Machine Learning.

Optical nanosensors, including single-walled carbon nanotubes (SWCNTs), provide real-time spatiotemporal reporting at the single-molecule level within a nanometer-scale area. However, their superior sensitivity also makes them susceptible to slight environmental influences such as reference analytes in media, external fluid flow, and mechanical modulations. Consequently, they often fail to achieve the optimal limit of detection (LOD) and frequently convey misinformation spatiotemporally. To address this challenge, we developed a single-pixel mapping technique for optical nanosensor arrays that operates with high spatiotemporal precision using machine learning. We systematically measured the spatial sensing images of various analyte concentrations below the LOD by using a near-infrared (nIR) fluorescent SWCNT nanosensor array. For dopamine (DA) as an example analyte, we extracted single-pixel level sensing features such as entropy, the Laplacian operator, and neighboring values under noise levels. We then trained the artificial intelligence (AI) model to accurately identify specific reaction pixels of the nanosensor array, even below the LOD region. Additionally, our method can distinguish subtle noise caused by fluid in the media or mechanical modulation of the array substrate. As a result, our approach significantly improved the detection sensitivity of the nanosensor array, achieving a 13-fold increase over the original LOD and halving the detection time of the reporter pixels, with F1 scores exceeding 0.9. This method not only lowers the LOD of optical nanosensors but also isolates sensor responses specific to the analyte, providing accurate spatiotemporal information to the user, even in noisy conditions. It can be universally applied to various optical nanosensor materials and analytes, maximizing the sensitivity and accuracy of the nanosensors used in diagnostics and analysis.

Effects of corrugation on convective heat transfer and power generation in a wavy walled triangular cavity equipped with inclined elastic fin and piezo-energy harvester assembly

Piezoelectric energy harvesters are one of the energy conversion technologies that can be used to convert a variety of external sources, including wind, fluid motion, and vibrations, into electrical energy. This work suggests a novel wall corrugation design in addition to an elastic fin piezo assembly arrangement for power generation and thermal management in a triangular cavity during turbulent forced convection of air. Using the finite element method with ALE, the analysis is conducted for different values of fin inclination (γ between 0 and 60), corrugation amplitude (Af between 0.01H and 0.06H), corrugation frequency (Nf between 1 and 20) and fin distance from the mid-point of the inclined wall in wall direction. The average Nusselt number (Nu) and generated power (PW) show a non-linear increasing trend with increasing fin tilt. Average Nu increment factor becomes 5.17 with the highest fin inclination while the power increments become 11.6 and 4.46 when rising inclination from 30 to 45 and from 45 to 60. The generated power rises with higher corrugation amplitude and wave number. However, increasing the wave number results in thermal performance degradation. Increment of average Nu becomes 1.17 with highest corrugation amplitude while it declines by a factor of 10.3 at the highest wave number. Power enhancement factors of 5.73 and 2.32 are obtained by increasing the corrugation amplitude from Af = 0.0714H to Af = 0.1786H and from Af = 0.1786H to Af = 0.2143H. When fin positions sf = 0.7143H and sf = -0.7143H are compared with the case of fin location at sf = 0, the power increment factors become 12.27 and 4.76, respectively. For the power produced by the piezo device, a polynomial type correlation is suggested by adjusting the parameters of the corrugated wall.