Mechanical and Aerospace Engineering

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 protects cells from oxidative stress and H2O2-induced apoptosis, while partially restoring bioenergetics diminished by H2O2 exposure. These findings support initial evidence for the feasibility and potential advantages of mitochondrial therapy in auditory cells. If successful in animal models and ultimately in humans, this novel therapy offers prominent potential for the treatment of sensorineural hearing loss.

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 the hydrogen BWB-365 is 714 kg, compared to 916 kg for the conventional B777-300ER. Hydrogen aircraft configurations, on average, also show a 21% increase and 99.48% decrease in [Formula: see text] and [Formula: see text] emissions. Moreover, hydrogen BWB configurations exhibit reduced emissions compared to hydrogen T&W despite higher takeoff weights. This study underscores the potential of hydrogen SOFC/GT systems and BWB configurations to enhance efficiency and reduce the environmental impacts for future aircraft.

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), and an additional 2.0 EPNdB is achievable with a decreased maximum takeoff thrust engine variant. Community noise impacts of departure and arrival procedures are studied through comparison of single-event noise contours. Significant contour area reductions were observed when compared to conventional tube-and-wing aircraft of similar weight and range class. Further departure and approach noise reductions were modeled through additional full-flight procedure variations.

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 cooling performance compared to non-HYS counterparts. Overall, this study underscores the potential of HYS-infused PDMS films as a promising solution for passive radiative cooling, with broad applicability in diverse domains requiring efficient thermal management solutions. Additionally, these research insights pave the way for establishing an AI database for passive radiative cooling research, offering new avenues for further exploration and application in this field.

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 transfer to bring DEP onto a rotating disc without much circuitry. Our solution leverages the ongoing advances in the printed circuit board market to make low-cost cartridges (<$1) that can employ DEP, which was validated using yeast cells. The resulting DEPDisc platform solves the challenge that existing printed circuit board electrodes are reliant on expensive high-voltage function generators by boosting the voltage using resonant inductive power transfer. This work includes a device costing less than $100 and easily replicable with the information provided in the Supplementary material. Consequently, with DEPDisc we present the first DEP-based low-cost platform for cell handling where both the device and the cartridges are truly inexpensive.

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 micro-structures and macro-substrates enables the forming of continuous carbon nanofibers with a diameter of ~20 nm and allows the tensile strength of carbon fibers to be enhanced to 212 GPa through the combination of zigzag conformation and nanoscale effects. These advantages create opportunities for the application of maximizing nanoscale effects that have not previously been technically possible.

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.

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 accepted micro-kinetic model to evaluate the role of the EDL structure on the reaction kinetics prevents the optimization of the interface for improved reaction rates. In this talk, we propose a novel modeling framework for analyzing micro-kinetics that accounts for the contributions of EDL structure by leveraging our recently developed continuum EDL model [3] and density functional theory (DFT) calculations. Our previous work showed that the continuum model can accurately predict differential capacitance for EDL charging without necessitating parameter-fitting by incorporating microscopic interactions such as electron spillover, entropy due to solute size variation, and polarization of solvent and solute molecules [3]. We refine the continuum EDL model to account for the interactions between adsorbate coverage and EDL structure. This model utilizes DFT results, i.e., free energies and charge distributions of the adsorbates at potential of zero charge, as input properties. The model calculates the adsorbates’ coverage to minimize the total grand potential, while accounting for both the effect of electrostatic potential on the adsorbate free energy and the effect of adsorbate charge density on the electrostatic potential simultaneously. The transition state of the rate determining step is treated as an adsorbate species, with its coverage evaluated in the same manner as the other adsorbates, which is used to evaluate the reaction rate based on transition state theory. This model framework enables us to evaluate the intrinsic and electrolyte-dependent kinetic activity with reasonable computational resources. Finally, we apply this model to investigate the kinetics of hydrogen evolution and oxidation reactions (HER/HOR) having favorable comparisons with measured cation- and pH- dependent kinetics[4]. The results suggest that the charge distribution of the transition state can significantly affect electrolyte-dependent kinetics of electrochemical reactions, highlighting the importance of further analyzing the effects of EDL structures on reaction kinetics. Acknowledgements: This work was partially supported by the by the Center for Ionomer-based Water Electrolysis (CIWE), a DOE sponsored Energy Earthshot Research Center under contract number DE-AC02-05CH11231, and by a CRADA with Toyota Central R&D Labs., Inc. Part of this work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. The authors acknowledge the HydroGen Energy Materials Network from the Department of Energy, Hydrogen and Fuel Cell Technologies Office for funding under Contract numbers DE-AC02-05CH11231. Reference: [1] Shin, S.J., et al., On the importance of the electric double layer structure in aqueous electrocatalysis. Nat Commun, 2022. 13(1): p. 174. [2] Huang, J., Density-Potential Functional Theory of Electrochemical Double Layers: Calibration on the Ag(111)-KPF(6) System and Parametric Analysis. J Chem Theory Comput, 2023. 19(3): p. 1003-1013. [3] Shibata, M., S., et al., Parameter-fitting-free Continuum Modeling of Electrical Double Layer in Aqueous Electrolyte, Submitted. [4] Huang, B., et al., Cation- and pH-Dependent Hydrogen Evolution and Oxidation Reaction Kinetics. JACS Au, 2021. 1(10): p. 1674-1687. Figure 1

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.