Recent uci_eng_mae_oapdeposits items

Integrated Strain–Flow Analysis for Early Assessment of Right Ventricular Dysfunction in Pulmonary Arterial Hypertension

Thu, 21 May 2026 00:00:00 +0000

PurposeEarly detection of right ventricular (RV) dysfunction is essential in pulmonary arterial hypertension (PAH) but remains challenging using conventional echocardiography. This study investigates the feasibility of a noninvasive, physics-based framework using three-dimensional (3D) echocardiography that integrates myocardial strain and volumetric flow analysis to characterize RV mechanical performance across stages of PAH.MethodsA prospective pilot study (N = 15) enrolled healthy controls, PAH patients with preserved RV size, and PAH patients with RV dysfunction. Deformation was evaluated by principal strain analysis and by conventional (longitudinal, circumferential) components. Hemodynamic metrics included hemodynamic forces and energetic properties that were derived using a physics-informed volumetric echocardiographic particle image velocimetry (V-Echo-PIV) method applied to contrast-enhanced acquisitions.ResultsDeformation analysis revealed that longitudinal...

Integrating Aircraft Performance in Traffic Flow Management Analysis for Advanced Air Mobility

Mon, 27 Apr 2026 00:00:00 +0000

Integrating advanced air mobility (AAM) into existing airspace will require substantial research and development regarding how diverse vehicles can operate cooperatively and safely in congested environments. Effective integration of AAM will hinge on the ability to develop robust, alternative traffic flow management techniques tailored specifically to the unique demands of AAM. This research introduces an air traffic management simulation framework for AAM operations, implemented in the open-source platform BlueSky. The framework characterizes airspace through demand models and vertiport networks and integrates high-fidelity vehicle performance and source noise models, enabling a deeper evaluation of flow management methods and the connection between noise and aircraft operations for mixed fleets of unique AAM vehicles. Performance is assessed through metrics of efficiency, safety, energy usage, and community noise exposure. The framework is exercised for an example AAM airspace...

Analysis of Operational Factors Contributing to Aircraft Overflight Noise Variation

Mon, 27 Apr 2026 00:00:00 +0000

Significant variations in measured overflight noise are observed from airport monitor networks, even for similar aircraft flying comparable operational procedures. Operational factors, including aircraft configuration, acceleration and deceleration procedures, thrust profiles, and associated environmental factors, can impact noise. To assess these impacts, operational Automatic Dependent Surveillance–Broadcast surveillance and weather data were associated with noise monitor recordings for a 3-year period at Seattle-Tacoma and John Wayne International Airports for Boeing 737-800, Boeing 737-700, and Airbus A320 aircraft. The impact of flight procedures on noise observations is assessed by evaluating flight profiles by airline to investigate the impact of differences in departure and arrival procedures. It was observed that aircraft weight and thrust correlate positively with noise on departure. At John Wayne Airport, there is evidence that thrust variations can result in large...

Flapping-Wing Micro-Air-Vehicle Project (FMMAV)

Wed, 22 Apr 2026 00:00:00 +0000

We are a student-led research team dedicated to bridging the gap between natural flight and modern engineering by studying the complex aerodynamics of flapping wings. Our project focuses on evolving our quadflapper and novel prototypes into high-performance aerial vehicles that challenge the efficiency of traditional propeller drones.

UCI Rocket Project Solids: RPS-003 Light Fury

Fri, 17 Apr 2026 00:00:00 +0000

The UCI Rocket Project Solids (RPS) undergraduate team presents their 2025-26 design and manufacturing process for their latest rocket: Light Fury. RPS operates on a one-year design cycle while implementing new design aspects to expand the depth of the team's engineering capabilities. This APCP-based solid propellant rocket features a 5U Cubesat payload with a deployable rover and UCI's first-ever active control airbrake system, alongside custom-manufactured carbon fiber and fiberglass airframes and fins. Light Fury is set to compete in the 2026 International Rocket Engineering Competition in Texas, where the rocket must reach an exact 10,000ft. apogee achieved by the airbrake system. This poster details their progress throughout the 2025-26 year, from initial design choices, testing procedures, static fires, and launches on their testbed rocket: Night Fury.

HyperXite 9

Wed, 15 Apr 2026 00:00:00 +0000

The overall objective for HyperXite 9 was to design and build a more robust, and reliable pod, capable of proving the feasibility of a high-speed transportation system. We are working to improve a linear induction motor as the pod's propulsion system. We are also designing and implementing a thermal cooling system to actively dissipate the heat generated by this propulsion system. Our team is comprised of the following 7 subteams: Static Structures, Braking & Pneumatics, Dynamic Structures, Propulsion, Power Systems, Control Systems, and Outreach.

Effect of cell compression on the performance and the structure of proton exchange membrane water electrolyzer (PEMWE) assembly

Thu, 12 Mar 2026 00:00:00 +0000

In the field of water electrolysis, the proton exchange membrane water electrolyzer (PEMWE) is currently the most advanced technology for producing hydrogen without emitting CO2. Although PEMWE plants are already in operation, further research is needed to improve cell efficiency and reduce the use of rare materials, such as iridium oxide catalysts for the oxygen evolution reaction (OER). One of the main causes of performance loss in PEMWE is the relatively low electric conductivity of the porous transport layer (PTL) and of the anode catalyst layer, which results in ohmic losses and low catalyst utilization during high current density operation. The objective of this study is to investigate how optimization of the PTL and electrode interface can increase the cell performance. To this end, we tested different cell assemblies using fibrous and sintered PTLs, decreasing membrane thickness, reducing iridium loading, and inserting a microporous layer to increase contact surface area....

Using X-ray radiography to study oxygen flow in a proton exchange membrane electrolyzer operating under balanced pressure conditions

Wed, 11 Mar 2026 00:00:00 +0000

Of the various water electrolyzer technologies, the proton exchange membrane electrolyzer (PEMWE) is one of the best solutions for producing clean hydrogen without releasing CO2. In order to allow for widespread use of clean hydrogen, it is necessary to decrease its cost, which is intrinsically related to system operation. Current PEMWE plants operate in differential mode, directly pressurizing hydrogen and benefiting from thermodynamic compression, which increases overall system efficiency. However, high differential pressure above 30 bar can cause membrane stress, resulting in membrane creeping and failure. Pressurizing the water and operating at balanced pressure allows hydrogen to be produced at higher pressures while preserving the integrity of the membrane and porous layers. Nevertheless, the impact of pressurizing water on PEMWE performance must be better understood to maximize performance under balanced pressure conditions. This study examined the impact of water...

Frequency and leg stiffness adaptation in human vertical hopping before, during and after added load.

Fri, 30 Jan 2026 00:00:00 +0000

Terrestrial animal gaits often use spring-like mechanics to enhance movement economy through elastic energy cycling. Hopping is a relatively simple, constrained task, yet retains essential features of bouncing gaits, requiring cyclic regulation of limb stiffness and generation of high muscle forces to support body weight and enable elastic energy cycling. We investigated how humans adjust hopping frequency and leg stiffness before, during, and after experiencing added load. Eighteen participants hopped bipedally for 90 seconds per trial, with hop frequency and height unconstrained, while kinematic, ground reaction force, and ankle muscle electromyographic (EMG) data were collected. We analysed mechanics across four conditions: initial body weight (BWi), two added mass trials (+10% and +20% BW), and final body weight (BWf). With added mass, participants increased leg stiffness and maintained a consistent hopping frequency (∼2.15 Hz); yet, when returning to BWf, the elevated leg...

Foundation Models for Zero-Shot Segmentation of Scientific Images without AI-Ready Data

Fri, 2 Jan 2026 00:00:00 +0000

Zero-shot and prompt-based models have excelled at visual reasoning tasks by leveraging large-scale natural image corpora, but they often fail on sparse and domain-specific scientific image data. We introduce Zenesis, a no-code interactive computer vision platform designed to reduce data readiness bottlenecks in scientific imaging workflows. Zenesis integrates lightweight multimodal adaptation for zero-shot inference on raw scientific data, human-in-the-loop refinement, and heuristic-based temporal enhancement. We validate our approach on Focused Ion Beam Scanning Electron Microscopy (FIB-SEM) datasets of catalyst-loaded membranes. Zenesis outperforms baselines, achieving an average accuracy of 0.947, Intersection over Union (IoU) of 0.858, and Dice score of 0.923 on amorphous catalyst samples; and 0.987 accuracy, 0.857 IoU, and 0.923 Dice on crystalline samples. These results represent a significant performance gain over conventional methods such as Otsu thresholding and standalone...

Impact of Takeoff Trajectory Design on Performance and Noise for Advanced Air Mobility Aircraft

Mon, 22 Dec 2025 00:00:00 +0000

A broad range of advanced air mobility (AAM) aircraft are currently in development, each with varying community noise footprints and energy consumption depending on the specifics of their departure and arrival flight trajectories, which must be understood for effective airspace integration. This work presents a framework for analyzing AAM trajectory design, focusing on key performance characteristics, including community noise impact, energy consumption, and flight duration. The framework can be applied to diverse AAM vehicle types, as demonstrated in this work on a blown-flap short takeoff and landing vehicle, a tilt-rotor vertical takeoff and landing vehicle, and a lift-plus-cruise vertical takeoff and landing vehicle. Results of comparing various takeoff procedures for each vehicle show tradeoffs between community noise, energy consumption, and flight duration, highlighting the importance of strategic trajectory design.

Physical model and experimental validation of a high temperature proton exchange membrane electrochemical hydrogen pump cell for efficient single-stage extraction of low concentration hydrogen gas

Tue, 16 Dec 2025 00:00:00 +0000

There is interest in valorization of existing natural gas infrastructure to facilitate the co-transportation of hydrogen via blending of hydrogen gas initially at limited concentrations of 1–20 vol% H2 and to subsequently extract hydrogen at fuel cell quality standards (SAE J2719/ISO14687-2). High temperature proton exchange membrane electrochemical hydrogen pump (HT-PEM EHP) based on phosphoric acid doped polybenzimidazole (PA-PBI) exhibits good performance at elevated temperatures (>120 °C), which provides desirable tolerance to non-methane natural gas constituents that are problematic for lower temperature based EHP. To better understand the suitability of the HT-PEM EHP for such gas separation processes, a two-dimensional model of EHP based on PA-PBI was developed. The model is validated for several relevant operating conditions and across cells with differing amounts of phosphoric acid content in the electrodes. Operando micro x-ray computed tomography (CT) imaging...

Surface Charge in Electrical Double Layer as a Kinetic Descriptor of Electrocatalytic Reactions

Mon, 15 Dec 2025 00:00:00 +0000

The successful commercialization of electrochemical energy-conversion systems hinges on a deeper understanding of electrocatalytic reaction kinetics. Despite extensive research, a key descriptor that characterizes electrolyte effects on reaction kinetics remains elusive. Here, surface charge in electrical double layers (EDLs) is introduced as a descriptor for electrolyte-dependent kinetics. The surface charge is calculated with a continuum EDL model parameterized by density-functional theory. The model is validated by reproducing the anomalously low slope of Pt(111) in Parsons-Zobel plots. Strong correlations are observed between calculated surface charge and experimental kinetic currents for hydrogen evolution, oxygen reduction, and CO2-reduction reactions across various pH levels and cationic species. These correlations can be either promotional or inhibitory, depending on solute-intermediate interactions. In acidic media, incorporating adsorbate charge captures specific adsorption...

Assessment of mitochondrial viability under calcium Stress: Insights for mitochondrial transplantation

Thu, 20 Nov 2025 00:00:00 +0000

Mitochondrial transplantation has emerged as a promising cardioprotective strategy for ischemia-reperfusion injury, aiming to restore bioenergetic function by delivering healthy mitochondria to damaged tissue. However, conflicting reports exist regarding whether mitochondria can survive exposure to the calcium-rich extracellular environment, such as the bloodstream, prior to cellular uptake. Resolving this question is essential for advancing the therapeutic use of mitochondria in clinical settings. Isolated mitochondria from L6 rat skeletal muscle cells were incubated with physiologic (1.3 mM), sub-physiologic (0.65 mM), and supraphysiologic (2.6 mM) concentrations of calcium. Mitochondrial membrane potential was assessed using MitoTracker™ Red FM fluorescence, and structural integrity was evaluated using impedance-based Coulter counter analysis over a 12-hour time course. Mitochondria exposed to 1.3 mM calcium retained 90-95 %...

Spherical exoskeleton for the measurement of shoulder movement

Wed, 8 Oct 2025 00:00:00 +0000

Spherical exoskeleton for the measurement of shoulder movement

Enhancing water and oxygen transport through electrode engineering for AEM water electrolyzers

Tue, 9 Sep 2025 00:00:00 +0000

Anion-exchange membrane water electrolyzers (AEMWEs) can accelerate the deployment of more efficient and affordable hydrogen production solutions. Here, electrode structure is shown to affect water back-diffusion and oxygen transport, which, in return, governs overpotential behaviors in AEMWEs. Measurements indicate that electrode with copious catalytic sites produces water close to the AEM, creating a higher water gradient and driving water back-diffusion, which improves membrane hydration and mass transport. In situ measurement reveals a high pH gradient near the anode surface, which affects anode kinetics. Operando measurement shows reduced oxygen accumulation when decoupling oxygen production and transport on anode. Catalyst ink rheology and stability are tuned with additives to realize scalable fabrication of electrodes with enhanced transport features, allowing AEMWE to operate at 2 A cm−2 for over 1,000+ h at a 2.3 μV h−1 degradation rate. Analysis during and post-durability...

Economic Feasibility Study of Deploying Green H2 Infrastructure at Los Angeles International Airport (LAX)

Thu, 4 Sep 2025 00:00:00 +0000

Air transportation is among the critically debated subjects, contributing to approximately 2.5% of global CO2 emissions 1. The main strategy for addressing environmental concerns related to aviation emissions is the shift to low-carbon propulsion technologies for aircraft. Hydrogen could be introduced to the aviation sector as a fuel for fuel cell-powered aircraft or for direct combustion jet engines, with anticipated zero- to low-carbon emissions 2. Moreover, the universe lightest element possesses a very high gravimetric energy density of 120 MJ/kg, which will be higher when stored in cryogenic hydrogen form3, making it an ideal alternative to conventional aviation fuels (for example, jet fuel). This study provides a techno-economic analysis of introducing green hydrogen infrastructure to Los Angeles International Airport (LAX) to promote its transition towards sustainability. Preliminary research showed that the largest uncertainty in economic projections for H2-powered aviation...

Blended-Wing-Body Aircraft Design Framework for Vibroacoustic Modeling of Interior Cabin Noise

Thu, 4 Sep 2025 00:00:00 +0000

As the aviation industry seeks to reduce its environmental footprint while maintaining the growing demand for global connectivity, sustainable innovations are critical to the future of air travel. The blended-wing-body (BWB) aircraft offers significant potential, providing improved aerodynamic behavior, opportunities for hydrogen fuel integration, and reductions in emissions and noise pollution. This configuration's unique design introduces new challenges in managing interior cabin noise and structural vibrations. This work outlines the development of a multidisciplinary design framework for BWB aircraft that integrates a vibroacoustic modeling methodology to characterize the coupled relationship between interior cabin noise, varying panel thickness and material selection, and overall aircraft design. Two vehicle classes carrying 162 and 365 passengers, defined as the BWB-162 and BWB-365, are analyzed to demonstrate the framework's capabilities. Results show that the thickest...

A METHOD TO EXTRACT MODEL STRUCTURAL ASYMMETRIES IN DUAL-SHELL GYROSCOPES TO STUDY FREQUENCY DEGENERACY

Wed, 27 Aug 2025 00:00:00 +0000

We introduced a method to model structural asymmetries present in 3D Glassblown Fused Silica Dual-Shell micro-scale hemispherical resonator Gyroscopes (DSG). The method is based on acquisition of a sequence of high-magnification images which are digitally stitched together to create a combined high-resolution view of the critical features of the DSG. These images are then used to identify and measure structural asymmetries, which are subsequently used to construct a solid 3D model of the resonator with imperfections and followed by a Finite Element Method (FEM) analysis. Frequency mismatches of five devices were used to demonstrate the method, confirming to accurately predict mismatches -varying from 100 to 1000 Hz- for both n=2 and n=3 wineglass modes. The method presents a non-contact approach for studying the effect of non-idealities in the fabrication process for increasing the yield and quality of devices.

Proton Exchange Membrane (PEM) Water Electrolysis: Cell-Level Considerations for Gigawatt-Scale Deployment

Thu, 10 Jul 2025 00:00:00 +0000

Hydrogen produced with no greenhouse gas emissions is termed "green hydrogen" and will be essential to reaching decarbonization targets set forth by nearly every country as per the Paris Agreement. Proton exchange membrane water electrolyzers (PEMWEs) are expected to contribute substantially to the green hydrogen market. However, PEMWE market penetration is insignificant, accounting for less than a gigawatt of global capacity. Achieving substantive decarbonization via green hydrogen will require PEMWEs to reach capacities of hundreds of gigawatts by 2030. This paper serves as an overarching roadmap for cell-level improvements necessary for gigawatt-scale PEMWE deployment, with insights from three well-established hydrogen technology companies included. Analyses will be presented for economies of scale, renewable energy prices, government policies, accelerated stress tests, and component-specific improvements.

Techno-economic and environmental analysis of clean hydrogen deployment: A case study of Los Angeles International Airport

Tue, 8 Jul 2025 00:00:00 +0000

The primary strategy for addressing environmental concerns related to global aviation emissions is transitioning to low-carbon propulsion technologies. Hydrogen (H2) offers significant potential as a sustainable fuel, with anticipated zero to low carbon emissions. This study develops a methodological framework that integrates on-site electrolytic H2 production, storage, and transportation for airport applications. For the first time, the techno-economic feasibility of supplying clean liquid hydrogen (LH2) to Los Angeles International Airport (LAX) to support its transition toward sustainable operations by 2050 is comprehensively analyzed. The results underscore the critical role of integrating long-term H2 storage and short-term battery storage solutions to establish a reliable, self-sustained microgrid system at LAX. The estimated levelized cost of hydrogen (LCOH) ranges from $6.77 to $7.10 per kilogram of H2 in 2030, decreasing significantly to approximately $3.78 per kilogram...

Structured light imaging mesoscopy: detection of embedded morphological changes in superficial tissues

Mon, 30 Jun 2025 00:00:00 +0000

Significance

Current paradigms for the optical characterization of layered tissues involve explicit consideration of an inverse problem which is often ill-posed and whose resolution may retain significant uncertainty. Here, we present an alternative approach, structured light imaging mesoscopy (SLIM), that leverages the inherent sensitivity of raw spatial frequency domain (SFD) reflectance measurements for the detection of embedded subsurface scattering changes in tissue.

Aim

We identify wavelength-spatial frequency ( λ-fx ) combinations that provide optimal sensitivity of SFD reflectance changes originating from scattering changes in an embedded tissue layer. We specifically consider the effects of scattering changes in the superficial dermis which is a key locus of pathology for diverse skin conditions such as cancer, aging, and scleroderma.

Approach

We used Monte Carlo simulations in a four-layer skin model to analyze the SFD reflectance changes resulting...

Structured light imaging mesoscopy for detection of embedded morphological changes in superficial tissues

Mon, 30 Jun 2025 00:00:00 +0000

This study introduces Structured Light Imaging Mesoscopy (SLIM), a novel non-contact optical method for detecting subsurface morphological tissue alterations. By leveraging the inherent sensitivity of spatial frequency domain (SFD) reflectance measurements, SLIM identifies specific wavelength-spatial frequency combinations that optimize the detection of scattering changes in the superficial dermis, a key area for various skin conditions. Monte Carlo simulations across a range of skin tones revealed that these optimal combinations vary with melanin concentration. Specifically, in subjects with lighter skin tones optimal sensitivity is achieved using shorter wavelengths and higher spatial frequencies, while for darker skin tones longer wavelengths and lower spatial frequencies are preferred. This approach simplifies clinical tracking of subsurface microstructural changes by eliminating the need for complex inverse problem solving, enabling rapid data acquisition and minimal processing.

Structured light imaging mesoscopy: detection of embedded morphological changes in superficial tissues

Mon, 23 Jun 2025 00:00:00 +0000

Significance: Current paradigms for the optical characterization of layered tissues involve explicit consideration of an inverse problem which is often ill-posed and whose resolution may retain significant uncertainty. Here, we present an alternative approach, structured light imaging mesoscopy (SLIM), that leverages the inherent sensitivity of raw spatial frequency domain (SFD) reflectance measurements for the detection of embedded subsurface scattering changes in tissue. Aim: We identify wavelength-spatial frequency ( ) combinations that provide optimal sensitivity of SFD reflectance changes originating from scattering changes in an embedded tissue layer. We specifically consider the effects of scattering changes in the superficial dermis which is a key locus of pathology for diverse skin conditions such as cancer, aging, and scleroderma. Approach: We used Monte Carlo simulations in a four-layer skin model to analyze the SFD reflectance changes resulting from changes in superficial...

Initial outcomes of novel guideline-directed pharmacotherapy for systemic right heart failure in adults with congenital heart disease

Thu, 19 Jun 2025 00:00:00 +0000

Background: The combination therapy of angiotensin-converting enzyme inhibitors (ACEi) or alternatively angiotensin receptor-neprilysin inhibitors (ARNis), beta-blockers (BBs), mineralocorticoid receptor antagonists (MRAs), and recently sodium-glucose co-transporter 2 inhibitors (SGLT2is) has been hailed as a breakthrough in heart failure treatment for patients with structurally normal hearts, with international guidelines recommending these as first-line therapies ("fantastic four"). However, specific recommendations for adult with congenital heart disease (ACHD) and systemic right ventricle (sRV), who are at heightened risk for heart failure, are largely based on clinical experience or position statements, lacking robust clinical trial data. This study aims to evaluate the effectiveness and tolerability of these medications in ACHD patients with sRV. Methods: This retrospective single-center cohort study included 21 adult patients with sRV and signs of heart failure [6 with...

Preclinical Evaluation of a Growth‐Accommodating Transcatheter Pulmonary Valve System for Young Children

Thu, 19 Jun 2025 00:00:00 +0000

BACKGROUND: Congenital heart defects affect approximately 1% of births in the United States and Europe, with >1 million children in the United States living with congenital heart defects. Many experience abnormalities in the right ventricular outflow tract, often necessitating surgical intervention early in life. However, the initial repairs typically are temporary solutions as many patients will eventually need pulmonary valve replacement to address pulmonary valve regurgitation and prevent right ventricle failure. Addressing progressive pulmonary valve regurgitation, ideally in patients weighing 8 to 10 kg, is critical to prevent right ventricle dysfunction. Transcatheter pulmonary valve replacement currently treats patients weighing at least 20 kg. Unfortunately, smaller children must wait for valve replacement and risk right ventricular dilation. METHODS: To address this challenge, we have developed the IRIS Valve, a growth-accommodating transcatheter pulmonary heart valve...

Characterization of the Coating Layers Deposited onto Curved Surfaces Using a Novel Multi-Nozzle Extrusion Printer

Thu, 8 May 2025 00:00:00 +0000

Over the past two decades, additive manufacturing has advanced significantly, enabling rapid fabrication of functional components across various applications. In medical devices, it has been used for prototyping, prosthetics, drug delivery platforms, and more recently, tissue scaffolding. However, current technologies face challenges, particularly in depositing conformal layers over curved surfaces. This study introduces a novel multi-nozzle extrusion printer concept designed to deposit soft gel layers onto curved surfaces. A custom clearance locking mechanism enhances the printer's ability to achieve conformal coatings on both flat and curved substrates. We investigate key deposition parameters, including displacement volume and nozzle configuration, while comparing two deposition sequences: "Press and Express" and "Express and Press". Our results demonstrate that the "Express and Press" technique yields more uniform, merged conformal layers than the "Press and Express" method....

Low-cost optical sensors in electrified lab-on-a-disc platforms: liquid-phase boundary detection and automated diagnostics.

Sat, 26 Apr 2025 00:00:00 +0000

Centrifugal microfluidic platforms are highly regarded for their potential in multiplexing and automation, as well as their wide range of applications, especially in separating blood plasma and manipulating two-phase flows. However, the need to use stroboscopes or high-speed cameras for monitoring these tasks hinders the extensive use of these platforms in research and commercial settings. In this study, we introduce an innovative and cost-effective strategy for using an array of light-dependent resistors (LDRs) as optical sensors in microfluidic devices, particularly centrifugal platforms. While LDRs are attractive for their potential use as photodetectors, their bulky size frequently restricts their ability to provide high-resolution detection in microfluidic systems. Here, we use specific waveguides to direct light beams from narrow apertures onto the surface of LDRs. We integrated these LDRs into electrified Lab-on-a-Disc (eLOD) devices, with wireless connectivity to smartphones...

Divergent evolution of slip banding in CrCoNi alloys

Sat, 26 Apr 2025 00:00:00 +0000

Metallic materials under high stress often exhibit deformation localization, manifesting as slip banding. Over seven decades ago, Frank and Read introduced the well-known model of dislocation multiplication at a source, explaining slip band formation. Here, we reveal two distinct types of slip bands (confined and extended) in compressed CrCoNi alloys through multi-scale testing and modeling from microscopic to atomic scales. The confined slip band, characterized by a thin glide zone, arises from the conventional process of repetitive full dislocation emissions at Frank–Read source. Contrary to the classical model, the extended band stems from slip-induced deactivation of dislocation sources, followed by consequent generation of new sources on adjacent planes, leading to rapid band thickening. Our findings provide insights into atomic-scale collective dislocation motion and microscopic deformation instability in advanced structural materials.

Opportunities for Nanomaterials in Stretchable and Free‐Form Displays

Mon, 21 Apr 2025 00:00:00 +0000

Stretchable and free-form displays receive significant attention as they hold immense potential for revolutionizing future display technologies. These displays are designed to conform to irregular surfaces and endure mechanical strains, making them well suited for applications in wearable electronics, biomedical devices, and interactive displays. Traditional light-emitting devices typically employ brittle inorganic and metallic materials, which are not conducive to stretchability. However, replacing these nonflexible components with flexible/stretchable nanomaterials, soft organic materials, or their composites improves the overall flexibility and stretchability of devices. In this review, the roles and opportunities of nanomaterials, such as thin films, 1D nanofibrous materials, and micro/nanoparticles, are highlighted for enhancing the stretchability and overall performance of various types of light-emitting devices. By leveraging the unique mechanical and electrical properties...

Durability of Pt‐Alloy Catalyst for Heavy‐Duty Polymer Electrolyte Fuel Cell Applications under Realistic Conditions

Thu, 10 Apr 2025 00:00:00 +0000

Abstract As an emerging technology, polymer electrolyte fuel cells (PEFCs) powered by clean hydrogen can be a great source of renewable power generation with flexible utilization because of high gravimetric energy density of hydrogen. To be used in real‐life applications, PEFCs need to maintain their performance for long‐term use under a wide range of conditions. Therefore, it's important to understand the degradation of the PEFC under protocols that are closely related to the catalyst lifetime. Alloying Pt with transitional metal improves catalyst activity. It is also crucial to understand Pt alloys degradation mechanisms to improve their durability. To study durability of Pt alloys, accelerated stress tests (ASTs) are performed on Pt−Co catalyst supported on two types of carbon. Two different AST protocols were being studied: Membrane Electrolyte Assembly (MEA) AST based on the protocol introduced by the Million Mile Fuel Cell Truck consortium in 2023 and Catalyst AST, adopted...

Two decades of breakthroughs: charting the future of NeuroEngineering and Rehabilitation

Fri, 4 Apr 2025 00:00:00 +0000

The Journal of NeuroEngineering and Rehabilitation (JNER) has become a major actor for the dissemination of knowledge in the scientific community, bridging the gaps between innovative neuroengineering and rehabilitation. Major fields of innovations have emerged these last 25 years, such as machine learning and the ongoing AI revolution, wearable technologies, human machine interfaces, robotics, advanced prosthetics, functional electrical stimulation and various neuromodulation techniques. With the major burden of disorders impacting on the central/peripheral nervous system and the musculoskeletal system both in adults and in children, successful tailored neurorehabilitation has become a major objective for the research and clinical community at a world scale. JNER contributes to this challenging goal, publishing groundbreaking cutting-edge research using the open access model. The multidisciplinary approaches at the crossroads of biomedical engineering, neuroscience, physical...

Editorial for the Special Issue on MEMS/NEMS Devices and Applications, 2nd Edition

Thu, 3 Apr 2025 00:00:00 +0000

Microelectromechanical systems (MEMSs) and nanoelectromechanical systems (NEMSs) are revolutionary technologies that merge mechanical and electronic components on microscopic and nanoscopic scales [...].

Material characterization and biocompatibility of polycarbonate-based polyurethane for biomedical implant applications

Thu, 27 Mar 2025 00:00:00 +0000

Polycarbonate polyurethane (PCU) resins are widely used in biomedical applications due to their excellent mechanical properties, biocompatibility, and resistance to degradation. The performance of these materials in implantable devices depends on factors such as hardness, molecular weight, and their interactions with cells and tissues. Understanding the relationship between material properties and biological outcomes is essential for optimizing their use in medical devices. In this study, three PCU resins were selected for evaluation as potential polymer implant materials: Chronoflex (CF) 65D, and two Carbothane (CB) samples 95A with different molecular weights. Dynamic mechanical analysis (DMA) revealed that the storage modulus was primarily influenced by the hard domain content, with greater elasticity observed at higher frequencies and lower temperatures. Tensile hysteresis behavior at room temperature was strongly correlated with hardness, with lower hardness samples demonstrating...

Dynamic modeling of Hydrogen SOFC/GT powered Aircraft with integration analysis

Wed, 26 Mar 2025 00:00:00 +0000

This paper aims to advance the green transition of the aviation industry by introducing a dynamic modeling approach for the integration of hydrogen solid oxide fuel cells (SOFCs) and gas turbines (GTs) in aircraft propulsion. Despite the significant potential for emission reduction and improved fuel efficiency, the adoption of the SOFC/GT system in aviation is impeded by many factors, which include a lack of understanding of dynamic performance under diverse flight conditions. Through a comprehensive approach that leverages the STRIDES dynamic modeling program, this paper presents an analysis of the dynamic response and electrochemical characteristics of the system under the varying power demands of a flight. The designed system achieves efficiency of 71.4% and a power output of 1.29MW. The methodology also emphasizes the complexities of flight conditions and potential areas for system optimization and improvement. The study, with a focus on the rapid response of the SOFC/GT system...

Understanding Performance Limitation of Liquid Alkaline Water Electrolyzers

Tue, 25 Mar 2025 00:00:00 +0000

Liquid alkaline water electrolyzers (LAWEs), being the most commercially mature electrolysis technology, play a pivotal role in large-scale hydrogen production. However, LAWEs suffer from low operational efficiency, primarily due to un-optimized electrode structure and chemical compositions. Thus, we investigated how various electrode configurations could impact LAWE performance. Our results show that Ni felt electrodes outperform the conventional Ni foam thanks to improved electrochemical active surface area (ECSA) and preferred electrode surface structure that minimizes the micro-gaps in between the electrode and separator. By comparing the stainless steel (SS) felt electrodes with Ni felt electrodes, SS not only shows better oxygen evolution reaction activity but also improved hydrogen evolution reaction activity, which is less studied in the literature. We also show that a bilayer structure with small pore radius facing the separator could further improve LAWE performance...

Quaternions in Kinematics

Wed, 12 Mar 2025 00:00:00 +0000

Quaternions in Kinematics

Design Methodology of Hydrogen Solid Oxide Fuel Cells Propulsion System in Blended Wing Body Aircraft

Wed, 12 Mar 2025 00:00:00 +0000

This paper presents the design methodology for integrating a hydrogen solid oxide fuel cell/gas turbine (SOFC/GT) propulsion system into a blended-wing-body (BWB) aircraft and tubeand-wing (T&W) configurations for 365 and 162 passengers. The design methodology utilizes aircraft sizing and modeling tools that encompass aerodynamic properties, structural design, and powertrain integration. The proposed hydrogen BWB and T&W aircraft are compared against conventional models like the Boeing 777-300ER and 737-800. Key results indicate significant reductions in fuel consumption and emissions. For instance, the hydrogen BWB aircraft, on average, exhibits a 56% reduction in MJ of fuel energy consumption per passenger-kilometer compared to conventional aircraft. The analysis highlights the environmental benefits, with CO2 equivalent emissions per passenger-kilometer being significantly lower for hydrogen-powered models. The total takeoff weight per passenger for the hydrogen BWB-365...

Modeling Gas Diffusion Layers in Polymer Electrolyte Fuel Cells Using a Continuum-Based Pore-Network Formulation

Wed, 12 Mar 2025 00:00:00 +0000

Multiscale modeling of porous media in polymer electrolyte fuel cells is of paramount importance to improve predictions and assist the design of new materials. In this work, a composite-continuum-network formulation is presented to model species diffusion and convection in gas diffusion layers (GDLs). The model can be incorporated into CFD codes with moderate computational cost. The macroscopic model is based on a structured mesh composed of parallelepiped control volumes (CVs) and differential connectors (with negligible volume). The CV mesh embeds an internal structured pore network, which is used to determine analytically local anisotropic effective transport properties (effective diffusivity and permeability). The global structural parameters and effective transport properties predicted by the model are in good agreement with previous experimental data. Moreover, the results show that heterogeneities in the GDL can have significant influence on the fluxes from/to the catalyst...

A low-cost printed circuit board-based centrifugal microfluidic platform for dielectrophoresis

Fri, 28 Feb 2025 00:00:00 +0000

In recent decades, electrokinetic handling of microparticles and biological cells found many applications ranging from biomedical diagnostics to microscale assembly. The integration of electrokinetic handling such as dielectrophoresis (DEP) greatly benefits microfluidic point-of-care systems as many modern assays require cell handling. Compared to traditional pump-driven microfluidics, typically used for DEP applications, centrifugal CD microfluidics provides the ability to consolidate various liquid handling tasks in self-contained discs under the control of a single motor. Therefore, it has significant advantages in terms of cost and reliability. However, to integrate DEP on a spinning disc, a major obstacle is transferring power to the electrodes that generate DEP forces. Existing solutions for power transfer lack portability and availability or introduce excessive complexity for DEP settings. We present a concept that leverages the compatibility of DEP and inductive power...

Impact of Double Layer on Electrochemical Kinetics via Bottom up Multiscale Modeling Approach

Tue, 25 Feb 2025 00:00:00 +0000

Electric double layers (EDLs) play a fundamental role in various electrochemical processes such as colloidal dispersions, surface charging, and charge-transfer reactions. Increasingly, the role of EDLs on reaction kinetics is being studied [1] , revealing their importance in predicting the intrinsic and electrolyte-dependent kinetics of electrochemical reactions. Despite the extensive history of EDL modeling, there remain challenges in predicting the impact of EDL structure on reaction kinetics. The characteristic length of EDL for non-dilute solutions (typically 10 – 100 nanometers) exceeds the grasp of regular ab initio molecular dynamics (AIMD) simulations. While continuum models offer a means to estimate the quasi-equilibrium structure of EDLs with substantially lower computational cost than molecular dynamics, conventional continuum models require parameter fitting [2] due to their lack of appropriate expressions for microscopic interactions. Furthermore, the lack of a commonly...

Modeling the Environment-Dependent Kinetics of Oxygen Reduction Reaction – Effect of Relative Humidity

Tue, 25 Feb 2025 00:00:00 +0000

For proton exchange membrane fuel cells (PEMFCs) to achieve broad commercialization, the kinetics of oxygen reduction reaction (ORR) need to be better understood to improve the efficiency with minimized use of expensive Pt-based electrocatalyst(1). The increasing demands of PEMFC-powered heavy-duty vehicles make this issue critical, especially to meet the efficiency target (ultimately 72%)(2). Previous first principle-based theoretical analyses reasonably explained catalyst-dependent activity in ideal conditions (on single crystal catalysts in HClO4 solution under room temperature)(3). To design a practical catalyst, further analysis is required to bridge the gap between the ideal and actual PEMFC conditions (typically, covered with perfluorosulfonic acids under 60 to 90 °C, and 30 to 100% RH). In this talk, we examine the effect of relative humidity (RH) on ORR activity on a platinum surface. The effect of RH on ORR activity has been a controversial topic: an experimental study...

Enhancing Passive Radiative Cooling Films with Hollow Yttrium‐Oxide Spheres Insights from FDTD Simulation

Sat, 22 Feb 2025 00:00:00 +0000

Passive daytime radiative cooling (PDRC) presents a promising avenue for efficient thermal management without relying on electrical power. In this study, the potential of integrating Hollow Yttrium-Oxide Spheres (HYSs) within a Polydimethylsiloxane (PDMS) matrix to enhance PDRC is investigated. Through a combination of experimental characterization and computational analysis, the optical properties and radiative cooling performance of PDMS films embedded with HYSs are evaluated. These results demonstrate that HYSs significantly improve both solar reflectivity and long-wave infrared (LWIR) emissivity of the PDMS matrix. Finite-Difference Time-Domain (FDTD) simulations confirm the scattering efficiency of HYSs across various wavelength ranges, highlighting their effectiveness as additives for enhancing the radiative properties of passive cooling materials. Experimental validation reveals enhanced reflectivity and emissivity of PDMS films with embedded HYSs, resulting in superior...

Design of Hydrogen Solid Oxide Fuel Cells in Blended-Wing–Body Aircraft

Fri, 21 Feb 2025 00:00:00 +0000

This paper presents the design methodology for integrating a hydrogen solid oxide fuel cell/gas turbine (SOFC/GT) propulsion system into a blended-wing–body (BWB) aircraft and tube-and-wing (T&W) configurations for 365 and 162 passengers. The design methodology utilizes aircraft sizing and modeling tools that encompass aerodynamic properties, structural design, and powertrain integration. The proposed hydrogen BWB and T&W aircraft are compared against conventional models like the B777-300ER and B737-800. Key results indicate significant reductions in fuel consumption and emissions. For instance, the hydrogen BWB aircraft, on average, exhibits a 56% reduction in Megajoule of fuel energy consumption per passenger-kilometer compared to conventional aircraft. The analysis highlights the environmental benefits, with [Formula: see text] equivalent emissions per passenger-kilometer being significantly lower for hydrogen-powered models. The total takeoff weight per passenger for...

Flight Procedural Noise Assessment of Blended-Wing–Body Aircraft with Variable Thrust

Fri, 14 Feb 2025 00:00:00 +0000

Today’s commercial aviation industry centers on the tube-and-wing aircraft configuration with underwing-mounted engines, possibly nearing convergence on optimal performance capabilities with acceptable community noise. A potentially feasible breakthrough for obtaining lower noise levels for commercial aviation is the blended-wing–body (BWB), which presents unique noise-reducing characteristics such as engine shielding and simplified high-lift devices. The significance of characteristics unique to BWBs on overall aircraft noise is assessed through a study of a BWB aircraft design representative of the JetZero vehicle. This paper presents a methodology capable of modeling the aircraft’s propulsion system and corresponding performance capabilities necessary to assess the vehicle noise sources and overall community noise impact. Analysis of Part 36 certification noise levels indicates that the vehicle’smarginto Stage 5 standards is 35.8 effective perceived noise level (in EPNdB),...

Viscoelastic materials are most energy efficient when loaded and unloaded at equal rates

Tue, 4 Feb 2025 00:00:00 +0000

Biological springs can be used in nature for energy conservation and ultra-fast motion. The loading and unloading rates of elastic materials can play an important role in determining how the properties of these springs affect movements. We investigate the mechanical energy efficiency of biological springs (American bullfrog plantaris tendons and guinea fowl lateral gastrocnemius tendons) and synthetic elastomers. We measure these materials under symmetric rates (equal loading and unloading durations) and asymmetric rates (unequal loading and unloading durations) using novel dynamic mechanical analysis measurements. We find that mechanical efficiency is highest at symmetric rates and significantly decreases with a larger degree of asymmetry. A generalized one-dimensional Maxwell model with no fitting parameters captures the experimental results based on the independently characterized linear viscoelastic properties of the materials. The model further shows that a broader viscoelastic...

Autologous mitochondrial transplantation enhances the bioenergetics of auditory cells and mitigates cell loss induced by H2O2

Thu, 30 Jan 2025 00:00:00 +0000

Hearing loss is a widespread and disabling condition with no current cure, underscoring the urgent need for new therapeutic approaches for treatment and prevention. A recent mitochondrial therapy approach by introducing exogenous mitochondria to the cells has shown promising results in mitigating mitochondria-related disorders. Despite the essential role of mitochondria in hearing, this novel strategy has not yet been tested for the treatment of hearing loss. More importantly, whether cochlear cells take up exogenous mitochondria and its consequence on cell bioenergetics has never been tested before. Here, we showed that exogenous mitochondria from HEI-OC1 auditory cells internalize into a new set of HEI-OC1 cells through co-incubation in a dose-dependent manner without inducing toxicity. We observed that auditory cells that received exogenous mitochondria exhibited increased bioenergetics compared to the controls that received none. Furthermore, we found that mitochondrial transplantation...

Titrating chimeric antigen receptors on CAR T cells enabled by a microfluidic-based dosage-controlled intracellular mRNA delivery platform

Wed, 15 Jan 2025 00:00:00 +0000

Chimeric antigen receptor (CAR) T-cell therapy shows unprecedented efficacy for cancer treatment, particularly in treating patients with various blood cancers, most notably B-cell acute lymphoblastic leukemia. In recent years, CAR T-cell therapies have been investigated for treating other hematologic malignancies and solid tumors. Despite the remarkable success of CAR T-cell therapy, cytokine release syndrome (CRS) is an unexpected side effect that is potentially life-threatening. Our aim is to reduce pro-inflammatory cytokine release associated with CRS by controlling CAR surface density on CAR T cells. We show that CAR expression density can be titrated on the surface of primary T cells using an acoustic-electric microfluidic platform. The platform performs dosage-controlled delivery by uniformly mixing and shearing cells, delivering approximately the same amount of CAR gene coding mRNA into each T cell.

Optimization of process parameters in 3D-nanomaterials printing for enhanced uniformity, quality, and dimensional precision using physics-guided artificial neural network

Fri, 3 Jan 2025 00:00:00 +0000

Pneumatic 3D-nanomaterial printing, a prominent additive manufacturing technique, excels in processing advanced materials like MXene, crucial for applications in nano-energy, flexible electronics, and sensors. A key challenge in this domain is optimizing process parameters—applied pressure, ink concentration, nozzle diameter, and printing velocity—to achieve uniform, high-quality prints with the desired filament diameter. Traditional trial-and-error methods often result in significant material waste and time consumption. To address this, our study introduces a comprehensive pipeline that initially assesses whether the selected process parameters yield uniform, high-quality MXene prints. Subsequently, it employs a Physics-Guided Artificial Neural Network (PGANN) to predict the filament diameter based on these parameters, integrating fundamental physical principles of the printing process with experimental data. Our findings demonstrate that using an XGBoost classifier, we can classify...

Using a Webcam to Assess Upper Extremity Proprioception: Experimental Validation and Application to Persons Post Stroke

Thu, 2 Jan 2025 00:00:00 +0000

Many medical conditions impair proprioception but there are few easy-to-deploy technologies for assessing proprioceptive deficits. Here, we developed a method-called "OpenPoint"-to quantify upper extremity (UE) proprioception using only a webcam as the sensor. OpenPoint automates a classic neurological test: the ability of a person to use one hand to point to a finger on their other hand with vision obscured. Proprioception ability is quantified with pointing error in the frontal plane measured by a deep-learning-based, computer vision library (MediaPipe). In a first experiment with 40 unimpaired adults, pointing error significantly increased when we replaced the target hand with a fake hand, verifying that this task depends on the availability of proprioceptive information from the target hand, and that we can reliably detect this dependence with computer vision. In a second experiment, we quantified UE proprioceptive ability in 16 post-stroke participants. Individuals post stroke...

Air quality and health impacts of the 2020 wildfires in California

Wed, 1 Jan 2025 00:00:00 +0000

Background: Wildfires in 2020 ravaged California to set the annual record of area burned to date. Clusters of wildfires in Northern California surrounded the Bay Area covering the skies with smoke and raising the air pollutant concentrations to hazardous levels. This study uses the Fire Inventory from the National Center for Atmospheric Research database and the Community Multiscale Air Quality model to estimate the effects of wildfire emissions on air quality during the period from August 16 to October 28 of 2020. In addition, low-cost sensor data for fine particulate matter (PM2.5) from the PurpleAir network is used to enhance modeled PM2.5 concentrations. The resulting impacts on ozone and PM2.5 are used to quantify the health impacts caused by wildfires using the Benefits Mapping and Analysis Program – Community Edition. Results: Wildfire activity significantly increased direct PM2.5 emissions and emissions of PM2.5 and ozone precursors. Direct PM2.5 emissions surged up to...

Continuously superior-strong carbon nanofibers by additive nanostructuring and carbonization of polyacrylonitrile jetting

Sat, 28 Dec 2024 00:00:00 +0000

Carbon nanofibers show the advantages of scale effects on electrical and mechanical properties for applications such as aerospace1,2, automotive3,4, and energy5,6, but have to confront the challenge of maximizing the role of scale effects. Here, a method of additive nanostructuring and carbonization of polyacrylonitrile (PAN) jetting for the nano-forming of carbon fibers is developed by understanding the electrostatic submicro-initiation of a PAN jetting, altering the microstructure of PAN-based jetting fibers at the nanoscale and implementing subsequent carbonization of PAN jetting nanofiber. Using this method of additive nanostructuring and carbonization in combination with the radial distribution pattern of shear stress, we find that the conformation of some molecular chains inside the PAN nanofibers is transformed into the zigzag conformation. The ability to materialize and carbonize such PAN nanofibers with various conformational structures in the form of arrays on diverse...

Oxygen 1s X‑ray Photoelectron Spectra of Iridium Oxides as a Descriptor of the Amorphous–Rutile Character of the Surface

Thu, 21 Nov 2024 00:00:00 +0000

Characterization of the surface of iridium oxide (IrO_x) materials is of crucial importance to understand catalysts for the oxygen evolution reaction (OER) in low-temperature water electrolysis. While much of our current knowledge is based on well-defined single-crystal surfaces, surface-sensitive techniques like X-ray photoelectronic spectroscopy (XPS) are relevant to characterize the nanostructures considered. In this work, we describe a simple approach to use oxygen 1s spectra as an identifier of the amorphous/crystalline characteristics of iridium oxide structures from purely amorphous to purely crystalline. This conceptual approach was validated on seven commercially available materials. The presence of oxygen-associated defects in the surface moieties/species is shown even for purely crystalline materials with defect concentration increasing with greater amorphous character. This methodology provides us with an accessible ex situ descriptor of the...

Three-dimensional isotropic imaging of live suspension cells enabled by droplet microvortices

Thu, 14 Nov 2024 00:00:00 +0000

Fast, nondestructive three-dimensional (3D) imaging of live suspension cells remains challenging without substrate treatment or fixation, precluding scalable single-cell morphometry with minimal alterations. While optical sectioning techniques achieve 3D live cell imaging, lateral versus depth resolution differences further complicate analysis. We present a scalable microfluidic method capable of 3D fluorescent isotropic imaging of live, nonadherent cells suspended inside picoliter droplets with high-speed single-cell volumetric readout (800 to 1,200 slices in 5 to 8 s) and near-diffraction limit resolution (~216 nm). The platform features a droplet trap array that leverages flow-induced droplet interfacial shear to generate intradroplet microvortices, which rotate single cells on their axis to enable optical projection tomography (OPT)-based imaging. This allows gentle (~1 mPa shear stress) observation of cells encapsulated inside nontoxic isotonic buffer droplets, facilitating...

Movement Diversity and Complexity Increase as Arm Impairment Decreases After Stroke: Quality of Movement Experience as a Possible Target for Wearable Feedback

Wed, 13 Nov 2024 00:00:00 +0000

Upper extremity (UE) impairment is common after stroke resulting in reduced arm use in daily life. A few studies have examined the use of wearable feedback of the quantity of arm movement to promote recovery, but with limited success. We posit that it may be more effective to encourage an increase in beneficial patterns of movement practice - i.e. the overall quality of the movement experience - rather than simply the overall amount of movement. As a first step toward testing this idea, here we sought to identify statistical features of the distributions of daily arm movements that become more prominent as arm impairment decreases, based on data obtained from a wrist IMU worn by 22 chronic stroke participants during their day. We identified several measures that increased as UE Fugl-Meyer (UEFM) score increased: the fraction of movements achieved at a higher speed, forearm postural diversity (quantified by kurtosis of the tilt-angle), and forearm postural complexity (quantified...

Beyond two dimensions: Exploring 3D dielectrophoresis for microparticle control using carbon electrodes

Sat, 9 Nov 2024 00:00:00 +0000

This study explores the frontiers of microparticle manipulation by introducing an actuator platform for the three-dimensional positioning of microparticles using dielectrophoresis (DEP), a technique known for its selectivity and ease of integration with microtechnology. Leveraging advancements in carbon-based devices due to their biocompatibility and electrochemical stability, our work extends the application of DEP from two-dimensional constraints to precise 3D positioning within microvolumes, employing a photolithography-based fabrication process known as Carbon-MEMS technology (C-MEMS). We present the design, finite element simulation, fabrication, and testing of this platform, which utilizes a unique combination of planar and 3D carbon microelectrodes individually addressable on a transparent substrate. This setup enables the application of DEP forces, allowing for high-throughput manipulation of multiple microparticles simultaneously, as well as displacement of individual...

Membrane electrode assembly design to prevent CO2 crossover in CO2 reduction reaction electrolysis

Thu, 24 Oct 2024 00:00:00 +0000

To reach a net-zero energy economy by 2050, it is critical to develop negative emission technologies, such as CO2 reduction electrolyzers, but these devices still suffer from various issues including low utilization of CO2 because of its cross-over from the cathode to the anode. This comment highlights the recent innovative design of membrane electrode assembly, utilizing a bipolar membrane and catholyte layer that blocks CO2 cross-over and enables high CO2 single-pass utilization.

A general-purpose tool for modeling multifunctional thin porous media (POREnet): From pore network to effective property tensors

Thu, 24 Oct 2024 00:00:00 +0000

POREnet, a novel approach to model effective properties of thin porous media, TPM, is presented. The methodology allows the extraction of local effective property tensors by volume averaging from discrete pore networks, PNs, built on the tessellated continuum space of a TPM. The gradient theorem is used to describe 3D transport in bulk tessellated space, providing an appropriate metric to normalize network fluxes. Implemented effective transport properties include diffusivity, permeability, solid-phase conductivity, and entry capillary pressure and contact angle under two-phase conditions, considering multi-component materials with several solid phases and local contact resistances. Calculated property tensors can be saved on 3D image stacks, where interfacial and sub-CV scale features can be added before exporting data to CFD meshes for simulation. Overall, POREnet provides a general-purpose, versatile methodology for modeling TPM in an ample range of conditions...

The Current Landscape of Artificial Intelligence in Imaging for Transcatheter Aortic Valve Replacement

Thu, 24 Oct 2024 00:00:00 +0000

PurposeThis review explores the current landscape of AI applications in imaging for TAVR, emphasizing the potential and limitations of these tools for (1) automating the image analysis and reporting process, (2) improving procedural planning, and (3) offering additional insight into post-TAVR outcomes. Finally, the direction of future research necessary to bridge these tools towards clinical integration is discussed.Recent FindingsTranscatheter aortic valve replacement (TAVR) has become a pivotal treatment option for select patients with severe aortic stenosis, and its indication for use continues to broaden. Noninvasive imaging techniques such as CTA and MRA have become routine for patient selection, preprocedural planning, and predicting the risk of complications. As the current methods for pre-TAVR image analysis are labor-intensive and have significant inter-operator variability, experts are looking towards artificial intelligence (AI) as a potential solution.SummaryAI has...

Using operando techniques to understand and design high performance and stable alkaline membrane fuel cells

Thu, 24 Oct 2024 00:00:00 +0000

There is a need to understand the water dynamics of alkaline membrane fuel cells under various operating conditions to create electrodes that enable high performance and stable, long-term operation. Here we show, via operando neutron imaging and operando micro X-ray computed tomography, visualizations of the spatial and temporal distribution of liquid water in operating cells. We provide direct evidence for liquid water accumulation at the anode, which causes severe ionomer swelling and performance loss, as well as cell dryout from undesirably low water content in the cathode. We observe that the operating conditions leading to the highest power density during polarization are not generally the conditions that allow for long-term stable operation. This observation leads to new catalyst layer designs and gas diffusion layers. This study reports alkaline membrane fuel cells that can be operated continuously for over 1000 h at 600 mA cm−2 with voltage...

An optical system for cellular mechanostimulation in 3D hydrogels

Wed, 23 Oct 2024 00:00:00 +0000

We introduce a method utilizing single laser-generated cavitation bubbles to stimulate cellular mechanotransduction in dermal fibroblasts embedded within 3D hydrogels. We demonstrate that fibroblasts embedded in either amorphous or fibrillar hydrogels engage in Ca²⁺ signaling following exposure to an impulsive mechanical stimulus provided by a single 250 µm diameter laser-generated cavitation bubble. We find that the spatial extent of the cellular signaling is larger for cells embedded within a fibrous collagen hydrogel as compared to those embedded within an amorphous polyvinyl alcohol polymer (SLO-PVA) hydrogel. Additionally, for fibroblasts embedded in collagen, we find an increased range of cellular mechanosensitivity for cells that are polarized relative to the radial axis as compared to the circumferential axis. By contrast, fibroblasts embedded within SLO-PVA did not display orientation-dependent mechanosensitivity. Fibroblasts embedded in hydrogels and cultured...

Effect of cross-platform variations on transthoracic echocardiography measurements and clinical diagnosis

Thu, 10 Oct 2024 00:00:00 +0000

Aims: Accurate cardiac chamber quantification is essential for clinical decisions and ideally should be consistent across different echocardiography systems. This study evaluates variations between the Philips EPIQ CVx (version 9.0.3) and Canon Aplio i900 (version 7.0) in measuring cardiac volumes, ventricular function, and valve structures. Methods and results: In this gender-balanced, single-centre study, 40 healthy volunteers (20 females and 20 males) aged 40 years and older (mean age 56.75 ± 11.57 years) were scanned alternately with both systems by the same sonographer using identical settings for both 2D and 4D acquisitions. We compared left ventricular (LV) and right ventricular (RV) volumes using paired t-tests, with significance set at P < 0.05. Correlation and Bland-Altman plots were used for quantities showing significant differences. Two board-certified cardiologists evaluated valve anatomy for each platform. The results showed no significant differences...

A simple model for short-range ordering kinetics in multi-principal element alloys

Fri, 20 Sep 2024 00:00:00 +0000

Short-range ordering (SRO) in multi-principal element alloys influences material properties such as strength and corrosion. While some degree of SRO is expected at equilibrium, predicting the kinetics of its formation is challenging. We present a simplified isothermal concentration-wave (CW) model to estimate an effective relaxation time of SRO formation. Estimates from the CW model agree to within a factor of five with relaxation times obtained from kinetic Monte Carlo (kMC) simulations when above the highest ordering instability temperature. The advantage of the CW model is that it only requires mobility and thermodynamic parameters, which are readily obtained from alloy mobility databases and Metropolis Monte Carlo simulations, respectively. The simple parameterization of the CW model and its analytical nature makes it an attractive tool for the design of processing conditions to promote or suppress SRO in multicomponent alloys.

Intelligent gold nanocluster for effective treatment of malignant tumor via tumor-specific photothermal–chemodynamic therapy with AIE guidance

Mon, 9 Sep 2024 00:00:00 +0000

Precise and efficient therapy of malignant tumors is always a challenge. Herein, gold nanoclusters co-modified by aggregation-induced-emission (AIE) molecules, copper ion chelator (acylthiourea) and tumor-targeting agent (folic acid) were fabricated to perform AIE-guided and tumor-specific synergistic therapy with great spatio-temporal controllability for the targeted elimination and metastasis inhibition of malignant tumors. During therapy, the functional gold nanoclusters (AuNTF) would rapidly accumulate in the tumor tissue due to the enhanced permeability and retention effect as well as folic acid-mediated tumor targeting, which was followed by endocytosis by tumor cells. After that, the overexpressed copper ions in the tumor cells would trigger the aggregation of these intracellular AuNTF via a chelation process that not only generated the photothermal agent in situ to perform the tumor-specific photothermal therapy damaging the primary tumor, but also led to the copper...

How urban form impacts flooding

Mon, 9 Sep 2024 00:00:00 +0000

Urbanization and climate change are contributing to severe flooding globally, damaging infrastructure, disrupting economies, and undermining human well-being. Approaches to make cities more resilient to floods are emerging, notably with the design of flood-resilient structures, but relatively little is known about the role of urban form and its complexity in the concentration of flooding. We leverage statistical mechanics to reduce the complexity of urban flooding and develop a mean-flow theory that relates flood hazards to urban form characterized by the ground slope, urban porosity, and the Mermin order parameter which measures symmetry in building arrangements. The mean-flow theory presents a dimensionless flood depth that scales linearly with the urban porosity and the order parameter, with different scaling for disordered square- and hexagon-like forms. A universal scaling is obtained by introducing an effective mean chord length representative of the unobstructed downslope...

Real-Time Sensing of Upper Extremity Movement Diversity Using Kurtosis Implemented on a Smartwatch

Mon, 9 Sep 2024 00:00:00 +0000

Wearable activity sensors typically count movement quantity, such as the number of steps taken or the number of upper extremity (UE) counts achieved. However, for some applications, such as neurologic rehabilitation, it may be of interest to quantify the quality of the movement experience (QOME), defined, for example, as how diverse or how complex movement epochs are. We previously found that individuals with UE impairment after stroke exhibited differences in their distributions of forearm postures across the day and that these differences could be quantified with kurtosis-an established statistical measure of the peakedness of distributions. In this paper, we describe further progress toward the goal of providing real-time feedback to try to help people learn to modulate their movement diversity. We first asked the following: to what extent do different movement activities induce different values of kurtosis? We recruited seven unimpaired individuals and evaluated a set of 12...

A standardised approach to quantifying activity in domestic dogs

Wed, 4 Sep 2024 00:00:00 +0000

Objective assessment of activity via accelerometry can provide valuable insights into dog health and welfare. Common activity metrics involve using acceleration cut-points to group data into intensity categories and reporting the time spent in each category. Lack of consistency and transparency in cut-point derivation makes it difficult to compare findings between studies. We present an alternative metric for use in dogs: the acceleration threshold (as a fraction of standard gravity, 1 g = 9.81 m/s²) above which the animal's X most active minutes are accumulated (MX_ACC) over a 24-hour period. We report M2_ACC, M30_ACC and M60_ACC data from a colony of healthy beagles (n = 6) aged 3-13 months. To ensure that reference values are applicable across a wider dog population, we incorporated labelled data from beagles and volunteer pet dogs (n = 16) of a variety of ages and breeds. The dogs' normal activity patterns...

Generative Artificial Intelligence for Designing Multi-Scale Hydrogen Fuel Cell Catalyst Layer Nanostructures.

Fri, 23 Aug 2024 00:00:00 +0000

Multiscale design of catalyst layers (CLs) is important to advancing hydrogen electrochemical conversion devices toward commercialized deployment, which has nevertheless been greatly hampered by the complex interplay among multiscale CL components, high synthesis cost and vast design space. We lack rational design and optimization techniques that can accurately reflect the nanostructure-performance relationship and cost-effectively search the design space. Here, we fill this gap with a deep generative artificial intelligence (AI) framework, GLIDER, that integrates recent generative AI, data-driven surrogate techniques and collective intelligence to efficiently search the optimal CL nanostructures driven by their electrochemical performance. GLIDER achieves realistic multiscale CL digital generation by leveraging the dimensionality-reduction ability of quantized vector-variational autoencoder. The powerful generative capability of GLIDER allows the efficient search of the optimal...

Ubiquitous short-range order in multi-principal element alloys

Mon, 19 Aug 2024 00:00:00 +0000

Recent research in multi-principal element alloys (MPEAs) has increasingly focused on the role of short-range order (SRO) on material performance. However, the mechanisms of SRO formation and its precise control remain elusive, limiting the progress of SRO engineering. Here, leveraging advanced additive manufacturing techniques that produce samples with a wide range of cooling rates (up to 107 K s−1) and an enhanced semi-quantitative electron microscopy method, we characterize SRO in three CoCrNi-based face-centered-cubic (FCC) MPEAs. Surprisingly, irrespective of the processing and thermal treatment history, all samples exhibit similar levels of SRO. Atomistic simulations reveal that during solidification, prevalent local chemical order arises in the liquid-solid interface (solidification front) even under the extreme cooling rate of 1011 K s−1. This phenomenon stems from the swift atomic diffusion in the supercooled liquid, which matches or even surpasses the rate of solidification....

Hip load capacity and yield load in men and women of all ages

Sun, 18 Aug 2024 00:00:00 +0000

Quantitative computed tomography (QCT) based finite element (FE) models can compute subject-specific proximal femoral strengths, or fracture loads, that are associated with hip fracture risk. These fracture loads are more strongly associated with measured fracture loads than are DXA and QCT measures and are predictive of hip fracture independently of DXA bone mineral density (BMD). However, interpreting FE-computed fracture loads of younger subjects for the purpose of evaluating hip fracture risk in old age is challenging due to limited reference data. The goal of this study was to address this issue by providing reference data for male and female adult subjects of all ages. QCT-based FE models of the left proximal femur of 216 women and 181 men, age 27 to 90 years, from a cohort of Rochester, MN residents were used to compute proximal femoral load capacities, i.e. the maximum loads that can be supported, in single-limb stance and posterolateral fall loading (Stance_LC and...

Symmetry-enforcing neural networks with applications to constitutive modeling

Wed, 14 Aug 2024 00:00:00 +0000

The use of machine learning techniques to homogenize the effective behavior of arbitrary microstructures has been shown to be not only efficient but also accurate. In a recent work, we demonstrated how to combine state-of-the-art micromechanical modeling and advanced machine learning techniques to homogenize complex microstructures exhibiting non-linear and history dependent behaviors (Logarzo et al., 2021). The resulting homogenized model, termed smart constitutive law (SCL), enables the adoption of microstructurally informed constitutive laws into finite element solvers at a fraction of the computational cost required by traditional concurrent multiscale approaches. In this work, the capabilities of SCLs are expanded via the introduction of a novel methodology that enforces material symmetries at the neuron level, applicable across various neural network architectures. This approach utilizes tensor-based features in neural networks, facilitating the concise and accurate representation...

Achieving the hydrogen shot: Interrogating ionomer interfaces

Tue, 30 Jul 2024 00:00:00 +0000

The aim of this study is to enable the hydrogen economy and decarbonize various sectors in our environment that requires less expensive and more durable water electrolyzers, which can meet the Hydrogen-Shot target. The key is to improve the ionomer interfaces in low-temperature water electrolyzers as rapidly as possible, but to do so, it requires a systematic and holistic campaign combining both experiments and theory. In this perspective, we discuss the issues of electrolyzers and needs for translational science. We then present the approach that the Energy EarthShot Research Center: Center for Ionomer-based Water Electrolysis is taking in hopes of inspiring the community with this approach that can be leveraged to multiple problems and technologies.Graphical abstractHighlightsOne way to achieve the Hydrogen-Shot goal of low-cost, clean hydrogen, is advancing research and development on the interfaces of water electrolyzers for both performance and lifetime. The Center for Ionomer-based...

Epistemic virtue in higher education: testing the mechanisms of intellectual character development

Wed, 17 Jul 2024 00:00:00 +0000

Epistemic virtues are character traits conducive to principled ways of thinking, leading to a life of flourishing. Recent years have witnessed an emergence of theoretical accounts describing how they develop. However, few if any studies have conducted rigorous empirical investigation into the mechanisms of intellectual virtue development. In this study, we review several significant frameworks before utilizing a randomized, pretest/posttest control trial design to understand the impacts of a novel thinking disposition intervention on intellectual virtue growth. We ascertain the direct and indirect effects of the intervention on four key intellectual virtues: curiosity, humility, integrity, and tenacity. Additionally, we test theoretical mediators of virtue learning. Clear evidence favoring a theory-inspired mediator is observed, though we observe weaker signals of direct effects, with nuances across the virtues. For instance, tenacity and curiosity variables appear to respond...

Parameter-Fitting-Free Continuum Modeling of Electric Double Layer in Aqueous Electrolyte

Tue, 16 Jul 2024 00:00:00 +0000

Electric double layers (EDLs) play fundamental roles in various electrochemical processes. Despite the extensive history of EDL modeling, there remain challenges in the accurate prediction of its structure without expensive computation. Herein, we propose a predictive multiscale continuum model of EDL that eliminates the need for parameter fitting. This model computes the distribution of the electrostatic potential, electron density, and species' concentrations by taking the extremum of the total grand potential of the system. The grand potential includes the microscopic interactions that are newly introduced in this work: polarization of solvation shells, electrostatic interaction in parallel plane toward the electrode, and ion-size-dependent entropy. The parameters that identify the electrode and electrolyte materials are obtained from independent experiments in the literature. The model reproduces the trends in the experimental differential capacitance with multiple electrode...

Enhancing oxygen transport in the ionomer film on platinum catalyst using ionic liquid additives

Sat, 6 Jul 2024 00:00:00 +0000

The O₂ permeation barrier across the nanoscale ionomer films on electrocatalysts contributes to a major performance loss of proton exchange membrane (PEM) fuel cells under low Pt loading. Enhancing O₂ transport through the ionomer films is essential for developing low Pt loading catalyst materials in high-performance PEM fuel cells. This study found that adding an ionic liquid (IL) can effectively mitigate the dense ionomer ultrathin sublayer formed on the Pt surface, which severely hinders O₂ transport to the catalyst sites. The molecular dynamics simulation results show that adding the IL significantly alters the ionomer ultrathin sublayer structure by inhibiting its tight arrangement of perfluorosulfonic acid chains but scarcely impacts the ultrathin sublayer thickness. Additionally, the IL addition provides a larger free space for O₂ dissolution in the ultrathin sublayer. Consequently, due to IL molecules' presence, the O₂...

A single-center, assessor-blinded, randomized controlled clinical trial to test the safety and efficacy of a novel brain-computer interface controlled functional electrical stimulation (BCI-FES) intervention for gait rehabilitation in the chronic stroke population

Mon, 24 Jun 2024 00:00:00 +0000

BackgroundIn the United States, there are over seven million stroke survivors, with many facing gait impairments due to foot drop. This restricts their community ambulation and hinders functional independence, leading to several long-term health complications. Despite the best available physical therapy, gait function is incompletely recovered, and this occurs mainly during the acute phase post-stroke. Therapeutic options are limited currently. Novel therapies based on neurobiological principles have the potential to lead to long-term functional improvements. The Brain-Computer Interface (BCI) controlled Functional Electrical Stimulation (FES) system is one such strategy. It is based on Hebbian principles and has shown promise in early feasibility studies. The current study describes the BCI-FES clinical trial, which examines the safety and efficacy of this system, compared to conventional physical therapy (PT), to improve gait velocity for those with chronic gait impairment post-stroke....

Retraining and assessing hand movement after stroke using the MusicGlove: comparison with conventional hand therapy and isometric grip training

Mon, 17 Jun 2024 00:00:00 +0000

BackgroundIt is thought that therapy should be functional, be highly repetitive, and promote afferent input to best stimulate hand motor recovery after stroke, yet patients struggle to access such therapy. We developed the MusicGlove, an instrumented glove that requires the user to practice gripping-like movements and thumb-finger opposition to play a highly engaging, music-based, video game. The purpose of this study was to 1) compare the effect of training with MusicGlove to conventional hand therapy 2) determine if MusicGlove training was more effective than a matched form of isometric hand movement training; and 3) determine if MusicGlove game scores predict clinical outcomes.Methods12 chronic stroke survivors with moderate hemiparesis were randomly assigned to receive MusicGlove, isometric, and conventional hand therapy in a within-subjects design. Each subject participated in six one-hour treatment sessions three times per week for two weeks, for each training type, for...

Membrane Biophysics Define Neuron and Astrocyte Progenitors in the Neural Lineage

Sun, 16 Jun 2024 00:00:00 +0000

Neural stem and progenitor cells (NSPCs) are heterogeneous populations of self-renewing stem cells and more committed progenitors that differentiate into neurons, astrocytes, and oligodendrocytes. Accurately identifying and characterizing the different progenitor cells in this lineage has continued to be a challenge for the field. We found previously that populations of NSPCs with more neurogenic progenitors (NPs) can be distinguished from those with more astrogenic progenitors (APs) by their inherent biophysical properties, specifically the electrophysiological property of whole cell membrane capacitance, which we characterized with dielectrophoresis (DEP). Here, we hypothesize that inherent electrophysiological properties are sufficient to define NPs and APs and test this by determining whether isolation of cells solely by these properties specifically separates NPs and APs. We found NPs and APs are enriched in distinct fractions after separation by electrophysiological properties...

Flash heating process for efficient meat preservation

Mon, 27 May 2024 00:00:00 +0000

Maintaining food safety and quality is critical for public health and food security. Conventional food preservation methods, such as pasteurization and dehydration, often change the overall organoleptic quality of the food products. Herein, we demonstrate a method that affects only a thin surface layer of the food, using beef as a model. In this method, Joule heating is generated by applying high electric power to a carbon substrate in <1 s, which causes a transient increase of the substrate temperature to > ~2000 K. The beef surface in direct contact with the heating substrate is subjected to ultra-high temperature flash heating, leading to the formation of a microbe-inactivated, dehydrated layer of ~100 µm in thickness. Aerobic mesophilic bacteria, Enterobacteriaceae, yeast and mold on the treated samples are inactivated to a level below the detection limit and remained low during room temperature storage of 5 days. Meanwhile, the product quality, including visual appearance,...

Neural network kinetics for exploring diffusion multiplicity and chemical ordering in compositionally complex materials

Mon, 27 May 2024 00:00:00 +0000

Diffusion involving atom transport from one location to another governs many important processes and behaviors such as precipitation and phase nucleation. The inherent chemical complexity in compositionally complex materials poses challenges for modeling atomic diffusion and the resulting formation of chemically ordered structures. Here, we introduce a neural network kinetics (NNK) scheme that predicts and simulates diffusion-induced chemical and structural evolution in complex concentrated chemical environments. The framework is grounded on efficient on-lattice structure and chemistry representation combined with artificial neural networks, enabling precise prediction of all path-dependent migration barriers and individual atom jumps. To demonstrate the method, we study the temperature-dependent local chemical ordering in a refractory NbMoTa alloy and reveal a critical temperature at which the B2 order reaches a maximum. The atomic jump randomness map exhibits the highest...

Revealing in-plane movement of platinum in polymer electrolyte fuel cells after heavy-duty vehicle lifetime

Thu, 23 May 2024 00:00:00 +0000

Fuel cell heavy-duty vehicles (HDVs) require increased durability of oxygen-reduction-reaction electrocatalysts, making knowledge of realistic degradation mechanisms critical. Here identical-location micro-X-ray fluorescence spectroscopy was performed on membrane electrode assemblies. The results exposed heavy in-plane movement of electrocatalyst after HDV lifetime, suggesting that electrochemical Ostwald ripening may not be a local effect. Development of local loading hotspots and preferential movement of electrocatalyst away from cathode catalyst layer cracks was observed. The heterogeneous degradation exhibited by a modified cathode gas diffusion layer membrane electrode assembly after HDV lifetime was successfully quantified by the identical-location approach. Further synchrotron micro-X-ray diffraction and micro-X-ray fluorescence experiments were performed to obtain the currently unknown correlation between electrocatalyst nanoparticle size increase and loading change. A...

Environmental Analysis of Fleet-Wide Implementation of Delayed Deceleration Approaches

Thu, 23 May 2024 00:00:00 +0000

The capabilities and benefits of fleet-wide implementation of the delayed deceleration approach are presented through the modeled analysis of a day of implementation at Boston Logan International Airport. Conventional approach procedures can often involve early configuration in the flight trajectory, which results in aircraft having to deploy high-lift configurations early and thus having to operate at higher thrust levels. Employing a delayed deceleration approach involves delaying the configuration of high-lift devices and maintaining higher speeds for longer, thus allowing lower thrust settings and reducing approach fuel burn and community noise. There are challenges, however, with implementing delayed deceleration approach procedures on a fleet-wide basis. The deceleration rate for a given approach procedure can vary significantly depending on aircraft type, weight, and the procedure flown. In this work the study of an average day at Boston Logan International Airport is presented...

Methane Hydrate Structure I Dissociation Process and Free Surface Analysis

Mon, 20 May 2024 00:00:00 +0000

Methane hydrates are crystalline solids of water that contain methane molecules trapped inside their molecular cavities. Gas hydrates with methane as a guest molecule form structure I hydrates with two small dodecahedral cages and six tetra decahedral large cages. This study assesses the influence of occupation and the behavior of methane release from the molecular perspective during the dissociation process, particularly for the purpose of testing a series of molecular dynamics simulations. The dissociation cases conducted include an ideal 4 × 4 × 4 and 2 × 2 × 2 supercell methane hydrate system while inducing dissociation with two different types of temperature-rising functions for understanding the limitation and capability. These temperature-rising functions are temperature ramping and a single temperature step simulating in 5-7 various conditions. Temperature step results showed the earliest dissociation starting 50 ps into the simulation at an ΔT of 100 K, while at...

Methodology for Assessing Retrofitted Hydrogen Combustion and Fuel Cell Aircraft Environmental Impacts

Wed, 1 May 2024 00:00:00 +0000

Hydrogen (H2) combustion and solid oxide fuel cells (SOFCs) can potentially reduce aviation-produced greenhouse gas emissions compared to kerosene propulsion. This paper outlines a methodology for evaluating performance and emission tradeoffs when retrofitting conventional kerosene-powered aircraft with lower-emissionH2 combustion and SOFC hybrid alternatives. The proposed framework presents a constant-range approach for designing liquid hydrogen fuel tanks, considering insulation, sizing, center of gravity, and power constraints. A lifecycle assessment evaluates greenhouse gas emissions and contrail formation effects for carbon footprint mitigation, while a cost analysis examines retrofit implementation consequences. A Cessna Citation 560XLS+ case study shows a 5% mass decrease for H2 combustion and a 0.4% mass decrease for the SOFC hybrid, at the tradeoff of removing three passengers. The lifecycle analysis of green hydrogen in aviation reveals a significant reduction in CO2...

NSF DARE—Transforming modeling in neurorehabilitation: Four threads for catalyzing progress

Wed, 17 Apr 2024 00:00:00 +0000

We present an overview of the Conference on Transformative Opportunities for Modeling in Neurorehabilitation held in March 2023. It was supported by the Disability and Rehabilitation Engineering (DARE) program from the National Science Foundation’s Engineering Biology and Health Cluster. The conference brought together experts and trainees from around the world to discuss critical questions, challenges, and opportunities at the intersection of computational modeling and neurorehabilitation to understand, optimize, and improve clinical translation of neurorehabilitation. We organized the conference around four key, relevant, and promising Focus Areas for modeling: Adaptation & Plasticity, Personalization, Human-Device Interactions, and Modeling ‘In-the-Wild’. We identified four common threads across the Focus Areas that, if addressed, can catalyze progress in the short, medium, and long terms. These were: (i) the need to capture and curate appropriate and useful data necessary...

Pathways Toward Efficient and Durable Anion Exchange Membrane Water Electrolyzers Enabled By Electro‐Active Porous Transport Layers

Wed, 17 Apr 2024 00:00:00 +0000

Abstract Green hydrogen, produced via water electrolysis using renewable electricity, will play a crucial role in decarbonizing industrial and heavy‐duty transportation sectors. Anion exchange membrane water electrolyzers (AEMWEs) can overcome many of the performance and cost limitations of incumbent technologies, however, still suffer from durability challenges due to oxidative instability of anion‐exchange ionomers. Herein, the use of an electro‐active porous transport layer as anode (PTL‐electrode) is demonstrated to enable efficient and durable AEMWEs. The stainless‐steel PTL‐electrodes are shown to have superior performance and durability compared to traditional catalyst layers containing ionomer and nanoparticle catalysts. An AEMWE cell operating at 2 A cm −2 for over 600 h exhibited a degradation rate of just 5 µV h −1 . During operation, the surface composition of the stainless steel transforms into a mixture of iron and nickel oxyhydroxides,...

Electrokinetic Manipulation of Biological Cells towards Biotechnology Applications

Mon, 15 Apr 2024 00:00:00 +0000

The presented study demonstrates the capability of the template-based electrokinetic assembly (TEA) and guidance to manipulate and capture individual biological cells within a microfluidic platform. Specifically, dielectrophoretic (DEP) focusing of K-562 cells towards lithographically-defined "wells" on the microelectrodes and positioning singles cells withing these "wells" was demonstrated. K-562 lymphoblast cells, are widely used in immunology research. The DEP guidance, particularly involving positive DEP (pDEP), enables the controlled guidance and positioning of conductive and dielectric particles, including biological cells, opening new directions for the accurate and efficient microassembly of biological entities, which is crucial for single cell analysis and other applications in biotechnology. The investigation explores the use of glassy carbon and gold as electrode materials. It was established previously that undiluted physiological buffer is unsuitable for inducing...

High-Precision Control of Plasma Drug Levels Using Feedback-Controlled Dosing

Sun, 7 Apr 2024 00:00:00 +0000

By, in effect, rendering pharmacokinetics an experimentally adjustable parameter, the ability to perform feedback-controlled dosing informed by high-frequency in vivo drug measurements would prove a powerful tool for both pharmacological research and clinical practice. Efforts to this end, however, have historically been thwarted by an inability to measure in vivo drug levels in real time and with sufficient convenience and temporal resolution. In response, we describe a closed-loop, feedback-controlled delivery system that uses drug level measurements provided by an in vivo electrochemical aptamer-based (E-AB) sensor to adjust dosing rates every 7 s. The resulting system supports the maintenance of either constant or predefined time-varying plasma drug concentration profiles in live rats over many hours. For researchers, the resultant high-precision control over drug plasma concentrations provides an unprecedented opportunity to (1) map the relationships between pharmacokinetics...

3D Centrifugation‐Enabled Priming of Synaptic Activation Promotes Primary T Cell Expansion

Tue, 2 Apr 2024 00:00:00 +0000

Abstract Autologous cell therapy depends on T lymphocyte expansion efficiency and is hindered by suboptimal interactions between T cell receptors (TCR) and peptide‐MHC molecules. Various artificial antigen presenting cell systems that enhance these interactions are often labor‐intensive, fabrication costly, highly variable, and potentially unscalable toward clinical setting. Here, 3D centrifugation‐enabled priming of T cell immune‐synapse junctions is performed to generate tight T cell–Dynabead aggregates at a rate 200‐fold faster than that of conventional 24‐h bulk shaking. Furthermore, by forming T cell–Dynabead aggregates in the starting culture, two‐ to sixfold greater T cell expansion is achieved over conventional T cell expansion for cancer patient‐derived primary T cells while limiting over‐activation. Creating 3D T cell–Dynabead aggregates as the “booster” material enables highly efficient polyclonal T cell expansion without the need for complex surface modification of...

Doxorubicin Conjugated γ-Globulin Functionalised Gold Nanoparticles: A pH-Responsive Bioinspired Nanoconjugate Approach for Advanced Chemotherapeutics

Sat, 2 Mar 2024 00:00:00 +0000

Developing successful nanomedicine hinges on regulating nanoparticle surface interactions within biological systems, particularly in intravenous nanotherapeutics. We harnessed the surface interactions of gold nanoparticles (AuNPs) with serum proteins, incorporating a γ-globulin (γG) hard surface corona and chemically conjugating Doxorubicin to create an innovative hybrid anticancer nanobioconjugate, Dox-γG-AuNPs. γG (with an isoelectric point of ~7.2) enhances cellular uptake and exhibits pH-sensitive behaviour, favouring targeted cancer cell drug delivery. In cell line studies, Dox-γG-AuNPs demonstrated a 10-fold higher cytotoxic potency compared to equivalent doxorubicin concentrations, with drug release favoured at pH 5.5 due to the γ-globulin corona's inherent pH sensitivity. This bioinspired approach presents a novel strategy for designing hybrid anticancer therapeutics. Our study also explored the intricacies of the p53-mediated ROS pathway's role in regulating cell fate,...

Abstract 15472: The IRIS™ Valve: A Growth Accommodating Transcatheter Pulmonary Valve for Pediatric Patients

Thu, 29 Feb 2024 00:00:00 +0000

Introduction: It is estimated that at least 1 million children are living with a congenital heart defect (CHD) in the U.S. Most of these patients are born with some degree of right ventricular outflow tract (RVOT) abnormalities that at some point require pulmonary valve replacement to mitigate the detrimental effects of pulmonary valve regurgitation (PVR) on the right ventricle (RV). Due to their size, available solutions, e.g., the Melody™ valve (Medtronic Inc., Minneapolis, MN) cannot be implanted in small children under 20 Kg. Those must wait until they grow to a suitable weight to receive the valve, which may lead to RV dysfunction. Hypothesis: To mitiagte the detrminental effects to the RV, the IRIS™ valve is implantable at 12 mm with a 12-Fr delivery catheter. As the valve annulus grows, the valve would be balloon expanded up to 20 mm. Methods: The IRIS™ valve has...

Early Feasibility Study of a Hybrid Tissue-Engineered Mitral Valve in an Ovine Model

Thu, 29 Feb 2024 00:00:00 +0000

Tissue engineering aims to overcome the current limitations of heart valves by providing a viable alternative using living tissue. Nevertheless, the valves constructed from either decellularized xenogeneic or purely biologic scaffolds are unable to withstand the hemodynamic loads, particularly in the left ventricle. To address this, we have been developing a hybrid tissue-engineered heart valve (H-TEHV) concept consisting of a nondegradable elastomeric scaffold enclosed in a valve-like living tissue constructed from autologous cells. We developed a 21 mm mitral valve scaffold for implantation in an ovine model. Smooth muscle cells/fibroblasts and endothelial cells were extracted, isolated, and expanded from the animal's jugular vein. Next, the scaffold underwent a sequential coating with the sorted cells mixed with collagen type I. The resulting H-TEHV was then implanted into the mitral position of the same sheep through open-heart surgery. Echocardiography scans following the...

Abstract 14470: Right Ventricular Flow Visualization and Characterization via High Speed Volumetric Echo-PIV

Thu, 29 Feb 2024 00:00:00 +0000

Introduction: Although 4D echocardiography is used for many clinical applications, the evolving vortex flow in the right ventricle (RV) is relatively unknown and cannot be characterized with conventional echocardiography. An obstacle is that acquiring high frame rate (>100fps) data in presence of contrast is challenging and has not yet reported. Hypothesis: High frame-rate 4D echocardiographic data in presence of contrast can elucidate RV vortex flow via volumetric Echo-PIV (V-Echo-PIV). Methods: We devised a new transthoracic echocardiography (TTE) protocol using a Philips EPIQ CV9 ultrasound system with a 3D matrix probe (X5-1c) to acquire high frame-rate 4D data for processing with V-Echo-PIV. Apical RV focused view was used for full-volume acquisition by limiting the sector width and imaging depth solely to the entire RV. Visualization of the RV flow and wall dynamics...

Spherical nano-inhomogeneity with the Steigmann–Ogden interface model under general uniform far-field stress loading

Mon, 26 Feb 2024 00:00:00 +0000

An explicit solution, considering the interface bending resistance as described by the Steigmann–Ogden interface model, is derived for the problem of a spherical nano-inhomogeneity (nanoscale void/inclusion) embedded in an infinite linear-elastic matrix under a general uniform far-field-stress (including tensile and shear stresses). The Papkovich-Neuber (P-N) general solutions, which are expressed in terms of spherical harmonics, are used to derive the analytical solution. A superposition technique is used to overcome the mathematical complexity brought on by the assumed interfacial residual stress in the Steigmann-Ogden interface model. Numerical examples show that the stress field, considering the interface bending resistance as with the Steigmann–Ogden interface model, differs significantly from that considering only the interface stretching resistance as with the Gurtin–Murdoch interface model. In addition to the size-dependency, another interesting phenomenon is observed:...

A simple Galerkin meshless method, the Fragile Points method using point stiffness matrices, for 2D linear elastic problems in complex domains with crack and rupture propagation

Mon, 26 Feb 2024 00:00:00 +0000

The Fragile Points method (FPM) is an elementarily simple Galerkin meshless method, employing Point-based discontinuous trial and test functions only, without using element-based trial and test functions. In this study, the algorithmic formulations of FPM for linear elasticity are given in detail, by exploring the concepts of point stiffness matrices and numerical flux corrections. Advantages of FPM for simulating the deformations of complex structures, and for simulating complex crack propagations and rupture developments, are also thoroughly discussed. Numerical examples of deformation and stress analyses of benchmark problems, as well as of realistic structures with complex geometries, demonstrate the accuracy, efficiency, and robustness of the proposed FPM. Simulations of crack initiation and propagations are also given in this study, demonstrating the advantages of the present FPM in modeling complex rupture and fracture phenomena. The crack and rupture propagation modeling...

A new Fragile Points Method (FPM) in computational mechanics, based on the concepts of Point Stiffnesses and Numerical Flux Corrections

Mon, 26 Feb 2024 00:00:00 +0000

In this paper, a new method, named the Fragile Points Method (FPM), is developed for computer modeling in engineering and sciences. In the FPM, simple, local, polynomial, discontinuous and Point-based trial and test functions are proposed based on randomly scattered points in the problem domain. The local discontinuous polynomial trial and test functions are postulated by using the Generalized Finite Difference method. These functions are only piece-wise continuous over the global domain. By implementing the Point-based trial and test functions into the Galerkin weak form, we define the concept of Point Stiffnesses as the contribution of each Point in the problem domain to the global stiffness matrix. However, due to the discontinuity of trial and test functions in the domain, directly using the Galerkin weak form leads to inconsistency. To resolve this, Numerical Flux Corrections, which are frequently used in Discontinuous Galerkin methods are further employed in the FPM. The...

The influence of isolated femur and tibia rotations on patellar tendon stress: A sensitivity analysis using finite element analysis

Wed, 14 Feb 2024 00:00:00 +0000

The purpose of this study was to determine the influence of frontal and transverse plane rotations of the femur and tibia on peak maximum principal stress in the patellar tendon. Using finite element modeling, patellar tendon stress profiles of eight healthy individuals were obtained during a simulated squatting task (45° of knee flexion). The femur and tibia of each model were rotated 10° (in 2° increments) along their respective axes beyond that of the natural degree of rotation. This process was repeated for the transverse plane (internal and external rotation) and frontal plane (adduction and abduction). Quasi-static loading simulations were performed to quantify peak maximum principal stress in patellar tendon. Internal and external rotations of the femur and tibia that exceeded 4° beyond that of the natural rotation resulted in progressively greater patellar tendon stress (p < 0.05). Incremental femur and tibia adduction and abduction resulted in an increase in patellar...

ADARNet: Deep Learning Predicts Adaptive Mesh Refinement

Wed, 14 Feb 2024 00:00:00 +0000

ADARNet: Deep Learning Predicts Adaptive Mesh Refinement

A Systematic Review of the Learning Dynamics of Proprioception Training: Specificity, Acquisition, Retention, and Transfer

Tue, 13 Feb 2024 00:00:00 +0000

OBJECTIVE: We aimed to identify key aspects of the learning dynamics of proprioception training including: 1) specificity to the training type, 2) acquisition of proprioceptive skills, 3) retention of learning effects, and 4) transfer to different proprioceptive skills. METHODS: We performed a systematic literature search using the database (MEDLINE, EMBASE, Cochrane Library, and PEDro). The inclusion criteria required adult participants who underwent any training program that could enhance proprioceptive function, and at least 1 quantitative assessment of proprioception before and after the intervention. We analyzed within-group changes to quantify the effectiveness of an intervention. RESULTS: In total, 106 studies with 343 participant-outcome groups were included. Proprioception-specific training resulted in large effect sizes with a mean improvement of 23.4 to 42.6%, nonspecific training resulted in medium effect sizes with 12.3 to 22% improvement, and no training resulted...

Multi-view information fusion using multi-view variational autoencoder to predict proximal femoral fracture load

Sat, 3 Feb 2024 00:00:00 +0000

Background: Hip fracture occurs when an applied force exceeds the force that the proximal femur can support (the fracture load or "strength") and can have devastating consequences with poor functional outcomes. Proximal femoral strengths for specific loading conditions can be computed by subject-specific finite element analysis (FEA) using quantitative computerized tomography (QCT) images. However, the radiation and availability of QCT limit its clinical usability. Alternative low-dose and widely available measurements, such as dual energy X-ray absorptiometry (DXA) and genetic factors, would be preferable for bone strength assessment. The aim of this paper is to design a deep learning-based model to predict proximal femoral strength using multi-view information fusion. Results: We developed new models using multi-view variational autoencoder (MVAE) for feature representation learning and a product of expert (PoE) model for multi-view information fusion. We applied the proposed...