Physics of Fluids

Cancer survival rates increase with earlier diagnosis. However, many cancers are diagnosed only after symptoms develop, in the later stages of cancer progression. We need a diagnostic tool that can detect cancer earlier. Circulating tumour cells (CTCs) are cells that detach from the main tumour and can enter the bloodstream. The capture and analysis of CTCs can provide an early indicator of cancer. However, rarity of CTCs in blood makes their efficient capture challenging. Inertial microfluidics can be utilised for a label-free separation of CTCs from white blood cells (WBCs) by manipulating cells in the microchannel based on cell properties, achieving good separation performance. Inertial microfluidic devices mainly rely on size-based separation. However, residual WBC carryover limits complete separation. Here, we show that cell mechanical heterogeneity plays a large role in the separation process and should be considered in the design of these devices. We simulate the migration dynamics of CTCs and WBCs in a straight microchannel using a 3D lattice-Boltzmann-immersed-boundary-finite-element solver. Our results demonstrate that WBC migration behaviour changes depending on the deformability of a CTC. The size and deformability of the cells have been shown to determine the cell-specific heteroclinic orbits leading to different interaction types, these interactions alter WBC migration resulting in more/less WBC carryover. This work highlights that both cell-specific heteroclinic orbits and single cell migration rates should be considered in the design of inertial microfluidics for separation.

This study demonstrates the feasibility of using a Teflon-AF-based tube-in-tube saturator for fast and precise adjustment of oxygen concentrations in liquids, extending its relevance to human cell culture applications beyond organ-on-chip systems. The system achieves high, near-saturation oxygen concentrations of the liquid phase, with performance influenced by various parameters such as temperature, volume flow rate, and tube length. We demonstrate that the tube-in-tube saturator exhibits high sensitivity to variations in these parameters at low oxygen concentrations, whereas this sensitivity diminishes as saturation is approached. To elucidate the underlying mass transfer processes, kinetic experiments were combined with computational fluid dynamics simulations. The simulation results are in good agreement with the experimental data, and the developed model enables a reliable prediction of oxygen concentrations in the liquid phase under varying operating conditions. Owing to its design, performance, versatility, and portability, this system introduces a new approach for the precise and rapid control of oxygen concentrations in liquids for microscale and macroscale human cell culture applications, offering seamless integration with natural vascular or artificial perfusion networks.

Chronic, mechanically resilient thrombi remain difficult to remove rapidly and safely using existing therapies, which are limited by slow treatment speeds, reduced efficacy against aged clots and risks associated with embolic debris. Here we introduce Constrained Laser-Induced Cavitation (CLIC), a novel approach that confines laser-induced cavitation bubble generation and collapse within a miniaturized waveguide to enhance thrombolysis. Optimized CLIC removed retracted clots at a mass-loss rate of 393.5 mg/min, [~]40-fold higher than reported state-of-the-art sonothrombolysis under similar conditions. Systematic variation of channel length and laser parameters showed that CLIC efficacy depends strongly on treatment geometry and cavitation dynamics. Post-treatment analysis revealed cylindrical channels consistent with clot removal dominated by fluid jetting and suction-driven evacuation, with cavitation shockwaves likely contributing a secondary role. Debris fragment measurements remained predominantly below a 1 mm embolic-risk threshold, consistent with a promising embolic safety profile. These findings establish CLIC as a viable strategy for rapid thrombolysis of chronic, mechanically resistant thrombi.

Introduction Anatomical endoscopic enucleation of the prostate (AEEP) techniques, including bipolar enucleation (B-TUEP), holmium laser enucleation (HoLEP), thulium laser enucleation (ThuLEP), and thulium fibre laser enucleation (ThuFLEP), demonstrate comparable clinical outcomes for benign prostatic hyperplasia. As clinical equivalence is increasingly established, cost becomes a key determinant of modality selection. We performed a cost minimisation analysis comparing index procedural costs across AEEP modalities from an institutional perspective. Methods A cost minimisation model was developed from the institutional perspective, incorporating amortised capital costs, maintenance, and consumables. In addition to the base-case scenario of 180 cases per year, we modelled two additional case volume scenarios: low (50 cases/year) and high (500 cases/year) volume. Thu:YAG laser fibres were modelled on two scenarios: disposable single-use, and reusable fibres (up to 10 cases per fibre). Breakeven analysis determined the threshold volume at which each laser modality achieves cost parity with B-TUEP, and one-way sensitivity analysis was performed on key cost parameters. Analysis was limited to index procedural costs calculated in Singapore dollars. Results At the base case of 180 cases per year, B-TUEP had the lowest index procedure cost (SGD 1,018), followed by ThuFLEP (SGD 1,584), ThuLEP (1,599), and HoLEP (SGD 1,655). Breakeven analysis demonstrated that HoLEP, ThuLEP, and ThuFLEP can never achieve cost parity with B-TUEP when laser fibres are single-use, as laser modalities carry higher costs on both capital and per-case dimensions. ThuLEP with reusable fibres (10 uses per fibre) was the only modality to cross below B-TUEP, at a breakeven volume of 198 cases per year. At 500 cases per year with reusable fibres, ThuLEP achieved the lowest cost (SGD 847), representing a 15.4% saving over B-TUEP. Sensitivity analysis identified annual case volume and B-TUEP loop cost as the most influential parameters. Conclusion Index procedural costs in AEEP are strongly influenced by case volume and consumable strategy. While B-TUEP remains cost-efficient at low volume, high-volume practice combined with reusable Thu:YAG fibre technology enables cost parity and potential cost advantage for laser enucleation. These findings highlight the importance of economies of scale and device utilisation in technology adoption.

Lung volume reduction is a treatment for chronic obstructive pulmonary disease (COPD) patients with severe emphysema. Currently, in vivo animal models are used as a first step to quantify the efficiency of novel lung volume reduction treatments. By quantifying lung volume reduction in ex vivo samples, animal testing may be reduced. This study proposes two new methods for quantifying lung volume reduction in ex vivo tissue: water displacement and three-dimensional (3D) scanning. Porcine lung lobes were inflated and treated with cyanoacrylate glue to simulate lung volume reduction. Volume changes were measured using a custom water displacement setup and in a ventilated setting using a handheld Artec Space Spider 3D surface scanner. Both techniques detected post-treatment volume reductions. Water displacement offers a simple, cost-effective approach for isolated lung lobes, while 3D scanning enables volumetric analysis of intact lungs under ventilated conditions. These methods provide a reliable intermediate step between in vitro and in vivo testing, reducing animal use and improving preclinical assessment of novel lung volume altering interventions.

Lymphatic endothelial cell (LEC) function is strongly tied to transitions between button- and zipper-like junctions that control fluid flow into vessels. Published methods quantifying junction morphology are limited to single cell analysis or use few quantitative metrics to describe junctions across LEC monolayers. Therefore, a novel 3-step image analysis pipeline was developed to identify new metrics that quantify differences in button- and zipper-like junctions in LECs. The pipeline used Cellpose, CellProfiler, and Fiji to analyze VE-cadherin expression across lymphatic vessels within a 3D microfluidic chip and quantify VE-cadherin radial intensity, number of objects, object size, branchpoints, end-points, and junction thickness. Tumor necrosis factor (TNF)- exposure produced but-ton-like junctions, and unexposed cells were zippered. Radial intensity was heightened at the cell membrane in zipper-like junctions while perinuclear intensity increased for but-ton-like junctions. Increased branchpoints, endpoints, objects per cell, and junction thick-ness were associated with junction buttoning, while increased object size was associated with junction zippering. Principle component analysis results reinforced these trends and identified metric combinations that represented each junctional state. Overall, this semi-automated pipeline quantified differences in VE-cadherin junction morphology across LEC monolayers and generated new quantitative metrics to expand the tools available for studying junction morphology in lymphatic vasculature.

Recent models describe drug release from polymeric nanoparticles through an analogy with the quantum tunneling effect, treating the delivery system as a static rectangular potential barrier. In this work, we argue that this analogy is structurally identical to the standard solution of the Schrodinger equation for a rectangular barrier, and that the introduction of a multifractal formalism to describe time evolution -- obtained via a formal Wick rotation (x [->] t) -- lacks direct physical justification. We propose, instead, to treat the barrier height as an effective function of time, Ueff(t) = U0 f(t), with f(t) varying slowly within the barrier region, reflecting the progressive degradation/swelling of the polymeric matrix, under two hypotheses for f(t)-- exponential decay and rational decay (Hill-type). Rather than the thick-barrier WKB approximation, the exact transmission formula is used throughout, which is real-analytic in f(t) and continues smoothly into the resonance (over-barrier) regime once the barrier collapses, avoiding the artificial step-like transitions produced by the WKB approximation used in earlier drafts of this work. Both hypotheses for f(t) predict a finite barrier collapse time, t*, whose dependence on the energy ratio m = U0/E differs qualitatively between them (t* {propto}ln m vs. t* {propto}(m-1)1/n), offering a distinguishable criterion from experimental release data. The model was tested against ex-vivo chicken-skin permeation kinetics of 5-FU digitized from Rata et al. [1] (three systems: NCA-1-5-FU, G-NCA-1-5-FU, G-5-FU). The exact formula substantially improved fit quality relative to the WKB approximation for all three systems. Fits were obtained by global optimization (differential evolution, polished with scipy.optimize.curve_fit for covariance estimates) rather than a single local search, which proved necessary: for G-5-FU and NCA-1-5-FU, the exponential family is well-identified (all parameter uncertainties below 11% and 6% of the estimates, respectively; R2 > 0.999), while the rational (Hill) family remained poorly identified for all three systems despite the improved formula - favoring, by parsimony, the simpler exponential model throughout. Only G-NCA-1-5-FU remained non-identified with m free. A sensitivity check fixing m at the G-5-FU-derived value (m = 1.377) resolves this non-identifiability for G-NCA-1-5-FU at negligible cost in fit quality, consistent with a shared energy ratio for that system; the same constraint applied to NCA-1-5-FU, however, degrades its (already well-identified) fit by a factor of [~]4 in maximum residual; its own energy ratio (m = 1.188 {+/-} 0.007) differs from the shared value by [~]4{sigma}, a formally significant difference, so a single universal m is rejected for the complete set of systems studied. Reference values from the original multifractal study [2-4] and candidate extensions to further aptamer-functionalized nanocarrier systems [5-7] are also discussed. We discuss the implications of this treatment and its limits of validity, and point out paths for further empirical validation.

Successful intracellular delivery requires a nanocarrier to adhere to the cell membrane, be wrapped and internalized and finally released into the cytoplasm before it is degraded. While the initial steps have been intensively studied, the intracellular release of a nanocarrier has received comparatively less attention and remains poorly understood. To understand the physical mechanisms that govern intracellular release, we investigate the escape of nanocarriers (radii 4.5{sigma} and 7{sigma} ) from a lipid vesicle using coarse-grained simulations. We represent a nanocarrier using the metaparticle model and the membrane using the three-beads Cooke-Deserno model. Starting from a fully endocytosed state, we systematically vary the repulsion between the nanoparticle and the lipid head groups and compare three release scenarios: passive release, localized inside-out activity from a drug-like source confined within the particle and activity distributed over the entire nanoparticle. An elastic-energy analysis shows that in a tensionless membrane escape requires crossing a large pore-expansion barrier of {approx} 68kBT for the smaller particle and {approx} 110kBT for the larger, making passive release thermodynamically improbable. Our results show that the smaller particle nonetheless escapes above a threshold repulsion, whereas the larger one remains trapped in a metastable state in which local membrane pores form but fail to grow beyond the particle diameter to allow successful release. Adding activity lowers the nucleation barrier and promotes earlier pore opening, but its effectiveness depends on how it is applied, i.e., a localized internal source assists release of the smaller particle yet is insufficient to systematically free the larger one, while activity distributed across the whole nanoparticle drives complete release even in the larger case. These results show that productive escape is governed by whether the resulting pore can evolve into a geometrically accessible release pathway, providing physical design principles for intracellular delivery by nanocarriers

Employing DLA methods, this paper explores the self-assembly of collagen fibers and resulting fibrosis at three scales up to the scale of regular lobule models. This allows a mechanistic exploration of the effects of collagen on drug transport (flow and diffusion) and metabolism. In addition, this method permits an analysis of fiber growth characteristics. First, variations of the DLA method of Parkinson et al (1994) will be used to generate multiple explicit collagen microfibril self-assembly using DLA particles in one dimension using cubic grid blocks of (4 mm)3 in a 240 x 20 x 20 grid model. The second stage will be to assess the consequences of various densities of these fibers in three dimensions on flow reductions at a higher scale. Here we utilize DLA methods in cubic grid blocks of (80 nm)3 to mimic 3D collagen self-assembly of fibrils. We then apply a pressure gradient or specified flow rates across a spatially gridded version of these models to quantify flow effects. This region represents a local zone of liver tissue affected by fibrosis. Analytic models of fibrotic effects on flow are employed for comparison. A third stage explores the implications of fibrosis in a liver lobule model using multiple grid blocks of size 3200 mm to represent the lobule tissue. Here, a continuum model of fiber density is employed, based on the previous two scales. The model also includes the effects of additional grid blocks representing sinusoidal flow paths found in the lobule. We contrast and quantify drug propagation and metabolism of molecular dissolved versus nanoparticle delivery vehicles in fibrotic media, achieved by upscaling explicit collagen distributions to appropriate average values.

Cell therapies hold transformative potential for treating cancer, neurologic disorders, organ failure, diabetes, and other conditions, but their widespread clinical deployment is constrained by the lack of scalable cryopreservation methods that maintain high post-thaw viability. Current standard practice using slow freezing can lead to cell death and impaired cell function. Vitrification offers an alternative by cooling samples rapidly enough to bypass ice formation entirely, better preserving cell structure and function. The high cooling and warming rates required for vitrification have previously been achieved by quenching microliter-scale samples directly into convective cooling and warming baths. Here, we present a cryopreservation platform that overcomes the throughput limitations of existing systems by combining a vibrating orifice aerosol generator with an impinging conical nozzle to generate and confine micrometer-scale droplets mid-flight in liquid nitrogen. This approach mitigates cooling losses due to the inverse Leidenfrost effect, increasing cooling and warming rates by nearly an order of magnitude compared to conventional droplet vitrification, while improving throughput by two orders of magnitude. To test the efficacy of this system, we cryoaerosolized and rewarmed human induced pluripotent stem cells, porcine red blood cells, and human dermal fibroblasts using only 190-25 wt% (2.5-3.7 M) permeating cryoprotective agent, achieving >90% post-thaw viability for HDFs and hiPSCs and 94% recovery for RBCs, with retained colony-forming capacity additionally demonstrated in hiPSCs. This work demonstrates the first scalable vitrification-based cryopreservation method capable of achieving both high cooling ({approx} 200, 000 K min-1) and warming rates ({approx} 1, 000, 000 K min-1) while maintaining the high-throughput processing required ([≥]100 mL h-1) for next-generation cell therapies. Significance StatementCell therapies require robust long-term storage methods to enable widespread clinical deployment. Current approaches utilizing refrigeration or small-scale vitrification cannot meet the scalability and viability requirements for next-generation therapeutics. In this work we demonstrate a cryoaerosolization process that achieves both ultra-rapid cooling rates (>200,000 {degrees}C min-1) and high throughput (>100 mL h-1) by generating micrometer-scale droplets and spraying in a liquid nitrogen impingement stream. Using only as little as 19 wt% cryoprotectant, we achieved >90% cell viability and maintained function, comparable to low-throughput methods, but at two orders of magnitude higher processing rates. We also introduce a just-in-time CPA loading approach that reduces toxicity exposure. This technique enables scalable vitrification-based cryopreservation of large-volume cell products.

Microbial fuel cells (MFCs) have been widely investigated as decentralized bioelectrochemical systems capable of converting organic substrates into electricity. However, their long-term autonomous operation is constrained by substrate depletion in the anode compartment, leading to metabolic starvation of electroactive biofilms and a decline in power output. Conventional MFC design treats substrate crossover through the membrane separator as a parasitic loss that reduces coulombic efficiency. In this work, we propose a conceptual inversion of this paradigm by considering controlled cathodic-to-anodic substrate crossover as a passive mechanism to sustain basal microbial metabolism during periods of substrate scarcity. A transport-reaction framework is developed to quantify the balance between membrane-mediated substrate flux and microbial maintenance demand within the anode biofilm. Based on this balance, a dimensionless maintenance crossover Damkohler number (Dam) is introduced to define three operational regimes: starvation-dominated (Dam >> 1), balanced autonomous (Dam {approx} 1), and crossover-dominated (Dam << 1). The framework integrates membrane transport theory with biofilm kinetics to evaluate the effects of separator properties, substrate gradients, and current-dependent electro-osmotic transport on system stability. Order-of-magnitude analysis indicates that achievable crossover fluxes span several orders of magnitude depending on separator characteristics, suggesting that membrane properties critically influence system behavior. This perspective reframes substrate crossover from a loss mechanism to a potential design variable, offering a conceptual tool for enhancing resilience and guiding separator selection in MFCs intended for long-duration, and low-maintenance operation. HighlightsO_LIControlled crossover can sustain microbial metabolism in MFCs C_LIO_LIIntroduces maintenance crossover Damkohler number (Dam) C_LIO_LIIdentifies regimes for autonomous and starvation operation C_LIO_LILinks membrane properties to long-term system stability C_LIO_LIReframes crossover as a design variable, not only a loss C_LI

Lipid nanoparticles (LNPs) are one of the leading platforms for delivering nucleic acid therapeutics, yet their efficacy is limited by physicochemical interactions with the extracellular matrix (ECM) that trap the particles before they reach target cells. PEGylated nanoparticles mitigate these interactions by forming a protective steric layer on their surfaces. However, there is a lack of a predictive tool that gives mechanistic insights about how PEG surface density governs the underlying interaction and results in enhanced diffusive transport of LNPs through the ECM. Here, we present a multiscale hierarchical computational framework that couples all-atom constant pH molecular dynamics (CpHMD) with a highly coarse-grained model of the complete LNP within a crosslinked hyaluronic acid (HA) network. These atomistic simulations resolve the free energy of interaction between the LNP surface and HA chains across varying PEG lipid compositions, and integrate these free energy profiles to inform the coarse-grained simulations of LNP transport through the matrix. This work highlights that even a slightly PEGylated surface depletes the near-contact shell between the LNP and HA chains, which disrupts their adhesive interactions. These protective PEG layers produce a sharp, non-linear enhancement in LNP diffusivities, with just 1% PEG increasing the diffusivity nearly eight-fold relative to bare LNPs, which remain trapped in the matrix structures. This work provides a quantitative estimate of how PEG surface density governs LNP transport through the ECM, which offers predictive guidance for engineering LNP surface properties in target-specific drug delivery.

Urban green infrastructure is increasingly promoted as a public-health intervention, yet the biological features that determine exposure to potentially beneficial plant-derived volatile compounds remain poorly understood. Here we quantified airborne terpenes and terpenoids across five contrasting urban greenspaces in Oxford, UK, and related chemical profiles to plant diversity, vegetation structure and surrounding habitat characteristics. Ambient air samples collected across spring and summer were analysed by thermal-desorption gas chromatography-mass spectrometry, alongside field surveys of taxonomic richness, canopy cover, vegetation volume and ground composition. Terpene and terpenoid scentscapes differed strongly among sites and through time, with monoterpenes dominating detected profiles. Sites with greater plant richness and greater vegetation volume below 1.5 m consistently showed higher terpene/terpenoid abundance, whereas total vegetation volume, canopy cover and tree abundance were weaker and less consistent predictors. These relationships were specific to plant-associated chemical classes and were not observed for predominantly anthropogenic volatile compounds. These patterns were resolved across only five independent sampling sites, and the relationships reported here should therefore be considered exploratory. Our findings suggest that human exposure to plant-derived volatiles in cities may be maximised not simply by increasing tree cover, but by designing biodiverse, structurally complex lower-to-mid-storey vegetation within the breathing zone. These results provide an empirical basis for incorporating scentscape ecology into health-oriented urban greenspace design.

Gas-bubble-enhanced focused ultrasound (FUSGB) is advancing clinically across a myriad of applications, including targeted drug delivery through transient blood-brain barrier opening (BBBO). Its broader translation requires a better understanding of the bioeffects that enable reproducible enhancement of barrier permeability while avoiding vascular injury, underscoring the need to clarify the relationship between acoustic exposure, bubble activity, and the biological response central to treatment optimization. These interactions are difficult to isolate in vivo, and acoustic reflections, geometry, and field distortion in conventional cultureware hinder quantitative in vitro studies. Herein, we present a theoretically and experimentally characterized ultrasound-transparent organ-on-chip device with >99.9% US transparency that enables quantitative in vitro modeling of the FUSGB procedure and study of BBBO. Furthermore, submicron bubbles (sMB, ~800nm) were fabricated and characterized. Acoustic dose-dependent subharmonic and broadband cavitation dose curves (SCD and BCD), as well as temporal responses, were studied. A 3-day accelerated Caco--2 surrogate barrier with a high TEER (~1200xcm2) was used to demonstrate US dose-dependent targeted barrier opening, visualized using an in vitro Evans Blue assay. Together, this study and its findings establish a foundation for quantitative in vitro modeling of FUS BBBO, as well as other US interactions in microphysiological systems, supporting systematic evaluation of procedural regimens, large-parameter-space optimization, acoustic safety window, and exposure conditions for brain drug delivery, and additionally enabling mechanistic insight into FUSGB BBBO.

1. Context. Capturing and identifying airborne biological matter (bioaerosols) enables detailed characterisation of ecological communities, but the cost and weight of existing commercially available active air samplers limits the deployment of multiple devices needed to realise this potential. 2. Method. We present the AberTrap, a lightweight (~50g), open-source (CC-BY-SA), programmable rotating-arm bioaerosol sampler that can be self-built from common laboratory components and makerspace equipment at low cost (ca {pound}20 per unit, exc. power supply). To characterise the device's performance, we first explored the influence of rotational speed and paddle design on aerosol capture under controlled conditions, using fluorescein and a range of biological aerosols (4.5-33 m). To demonstrate its utility for ecological applications, we then validated field performance in a species-rich broadleaf woodland (England, UK), deploying eight samplers over five days and identifying captured fungal aerosols by ITS2 metabarcoding. 3. Key results. Modifying paddle design allowed us to influence particle selection and capture efficiency. Slotted paddles captured significantly more aerosols than plain paddles despite sampling less air, which we traced to the concentration of aerosols at the paddle leading edges. This effect was most pronounced for the smallest particles and outweighs the influence of rotational speed. In the field, 20 daily samples (four samplers over five days) detected 2,431 fungal taxa, 78.9% of the Chao2-estimated total fungal richness. A single sampler captured only 59% of this richness. Continuous 5-day sampling recovered 78% of the taxa detected by daily sampling, indicating only modest paddle saturation over this period. Our time segregated design allowed us to infer dispersal dynamics; 35% of taxa were recorded only on one day, and 19% recorded across all five days. Overall, replicate AberTraps provided high sampling completeness. 4. Implications. The AberTrap provides a low-cost, lightweight and programmable alternative to commercial rotating-arm samplers, enabling levels of spatial and temporal replication impractical with existing devices. Low cost and portability facilitate deployment in remote or resource-limited contexts. Its open-source, adaptable design allows the device to be tailored for applications in biodiversity assessment, pathogen surveillance and ecological monitoring.

Devireddy et al. [1] previously showed that an enthalpy-based, macroscale model simulated tissue freezing histories are in close agreement with a coupled model incorporating cellular water transport and intracellular ice formation (IIF). That comparison, however, was performed for a limited set of tissue geometries, cooling conditions, and biophysical parameters. Here, we revisit that conclusion by reimplementing the published model from its governing equations and systematically expanding the parameter space to determine when microscale processes alter the predicted macroscale freezing response. We incorporate both surface catalyzed nucleation (SCN) and volume catalyzed nucleation (VCN) of intracellular ice with cellular osmotic dehydration and examine a broad range of tissue dimensions, cooling rates, convective boundary conditions, membrane permeabilities, cell sizes, activation energies, intracellular water fractions, and nucleation rates. Linearization of the cellular water transport equation about osmotic equilibrium yields an osmotic relaxation timethat can be compared with the local residence time of tissue undergoing phase change. Their ratio defines a dimensionless group, that organizes the transition between regimes in which the uncoupled enthalpy formulation and the coupled micro and macroscale formulation produce similar or substantially different results. Across the one-dimensional parameter space examined here, the two models remain within a prescribed thermal-error bound for the dimensionless group below approximately 0.1, whereas the discrepancy increases systematically above this threshold. Model divergence also depends on intracellular ice nucleation, i.e., when nucleation is sufficiently slow, cellular water transport can become rate limiting for latent heat release. Conversely, sufficiently rapid intracellular ice formation reduces the macroscopic discrepancy by providing an additional pathway for latent-heat release. Multidimensional simulations further show that geometry alone can move a nominally conventional freezing protocol into the coupled regime. In particular, multidirectional cooling can reduce the local residence time sufficiently to produce substantial differences in predicted frozen volume even when the corresponding thermal histories appear similar. Finally, we formulate an inverse approach for estimating IIF parameters from tissue scale thermal histories. Synthetic simulations indicate that parameter recovery is feasible within a finite range of cooling conditions, providing a testable strategy for future experimental measurements. Together, these results provide a mechanistic criterion for deciding when microscale biophysical processes must be retained in macroscale tissue-freezing models.

This brief communication presents two solutions for calculating absolute measures of error from time-difference-of-arrival (TDOA) positioning in underwater acoustic telemetry arrays. First, a Monte Carlo estimation of TDOA positioning error is derived. Next, a computationally inexpensive, approximate solution to the Monte Carlo method is presented. This approximate solution is achieved by solving the Jacobian of a closed-form TDOA positioning model. The positioning error covariance matrix returned from either method can then be used to report the accuracy of TDOA positions or utilized in state-space positioning models. Finally, calculations of the expected radial error are shown which serves as a simple summary statistic for reporting positioning error in real units.

Capillaric circuits (CCs) enable pre-programmed liquid handling through self-filling and passive valving governed by capillary forces, eliminating the need for external pumps and actuators. However, CCs optimized for high cohesion liquids (HCL) such as water are intrinsically unsuitable for programmed flow control of low cohesion liquids (LCL) such as oils and solvents because the high surface free energy needed for capillary flow of HCL results in uncontrolled, complete wetting by LCL. Here, we introduce a library of multiphase components including phase-to-phase valves (P2PV), hydro-pneumatic relays (HPR) and multiphase domino valves (MDVs) that collectively enable CCs to concomitantly process HCLs and LCLs. P2PVs use a pre-filled HCL to valve immiscible LCLs (e.g. oil) by confining the LCL, and upon triggering, hydraulically entrain it. To prevent uncontrolled mixing between miscible LCLs (e.g. ethanol) and the HCL, HPRs with an air gap and air waste are added to the P2PV. MDVs are further added and enable preprogrammed, sequential delivery of LCL and HCL by multiphase microfluidic chain reactions. Multiphase liquid processing is applied to automated, on-chip lipid nanoparticle (LNP) manufacturing, illustrating the potential of multiphase CCs.

Nanoplastic interactions with cell membranes can influence particle uptake, translocation, and biological effects, making their molecular description important for assessing the environmental and biological consequences of plastic pollution. However, molecular simulations generally represent nanoplastics using monodisperse polymer chains, whereas nanoplastics formed by environmental degradation are polydisperse. Here, we construct 4 nm polyethylene terephthalate (PET), polyethylene (PE), and polystyrene (PS) nanoparticles with lognormal molecular-weight distributions reported for degraded polymers, and with melt-like chain packing and entanglement. Using Martini coarse-grained molecular dynamics, we simulate their interactions for 10 microseconds with three lipid bilayers of increasing complexity. PE and PS insert rapidly and remain largely intact, whereas PET remains surface-associated and progressively releases individual chains. Fluid, polyunsaturated lipid environments undergo greater deformation and promote substantially more chain release, up to 56% of the chains for PET and 43% for PS. Release begins with the shortest chains and progressively extends to longer chains, while semicrystalline PE remains largely intact. In contrast, a size-matched monodisperse PS particle releases no chains and minimally perturbs the membrane. These results identify the molecular-weight distribution as a key determinant of nanoplastic-membrane interactions, and indicate that uniform model particles underestimate the release of polymer chains into biological membranes.

Spatial repellents represent a promising approach to complement existing malaria vector control interventions by reducing contact between mosquitoes and humans. However, the efficacy of passive spatial repellent devices may be affected by environmental conditions, particularly temperature and airflow, which can influence the release of volatile active ingredients. Active-release devices may provide more consistent delivery of spatial repellent compounds. We investigated the efficacy of a commercially available battery-powered spatial repellent device and a low-power solar-powered device designed for potential use in Africa. Laboratory trials were conducted to evaluate the efficacy of the two spatial repellent devices against Anopheles mosquitoes. Protective efficacy was assessed by comparing mosquito probing on human participants during spatial-repellent and control tests. The effect of the devices on mosquito entry into the test chamber was also assessed. The protective efficacy was 86% with the commercial battery-powered device and 80% with the low-power solar-powered device. A Wilcoxon rank-sum test showed that there was no significant difference between the performance of the two devices in terms of protective efficacy (p = 0.856) or entry inhibition (p = 0.7989). The low-power device could be charged using a small, household-level photovoltaic panel, to provide a potentially practical means of delivering spatial repellents in off-grid settings.