Alexander H. Slocum

Abstract Diseases of the posterior segment of the eye are a leading cause of irreversible vision loss, yet effective minimally invasive delivery of therapeutics to posterior ocular tissues remains challenging. While the suprachoroidal space (SCS) has emerged as a promising route for posterior segment drug delivery, current microneedle-based approaches rely on anterior access and drug spread throughout the SCS, providing limited control over localization to posterior regions such as the macula. Catheter-based techniques offer greater posterior reach but are invasive and unsuitable for widespread clinical use. There remains a need for a minimally invasive device capable of precise, localized delivery to posterior regions of the SCS. In this work, we present the design and proof-of-concept evaluation of a novel suprachoroidal injector engineered to enable controlled, posterior SCS access. The device incorporates a curved, scleral-depressor–inspired form factor and “side-firing” needle that allows access to posterior and equatorial regions of the globe, an adjustable microneedle with high-resolution extension, and visualization of the injection site using an indirect ophthalmoscope. The device was evaluated in-vivo in large porcine eyes, where fluorescein and viscoelastic were successfully injected into the posterior suprachoroidal space beneath the macula. Localization of the injectate was confirmed through fundus imaging. By overcoming anatomical access constraints and improving confidence in injection placement, this approach has the potential to expand the therapeutic applications of suprachoroidal drug delivery and enable new treatments requiring spatially targeted posterior segment delivery.

Computational Fluid Dynamics (CFD) can be used to characterize lyophilization vacuum systems, but these simulations are typically unique to a specific geometry. This work presents a general method for predicting pressure performance by concatenating CFD and analytical models of individual components to create a vacuum system model. This method enables rapid exploration of vacuum system layouts to build custom geometry lyophilizers, which is particularly useful for novel continuous lyophilization systems. A vacuum chamber was built to validate this pressure prediction method. The simulations were then used to design a larger vacuum tunnel for continuous lyophilization that could achieve a target pressure below 10 Pa throughout its length. This tunnel was then built, and its performance matched the predictions of the component concatenation method. These results indicate that the component simulation and concatenation methods can be effectively used to predict the vacuum performance of custom geometry lyophilization systems.

Pharmaceutical lyophilization (vacuum freeze-drying) removes water from aqueous drug products to stabilize formulations. This work presents a continuous final-dose pharmaceutical lyophilizer that can integrate with continuous production chains, increasing process quality, speed, and flexibility. Performance is assessed by freeze-drying various model formulations, and the cakes produced showed no visual defects, low residual moisture, and no loss in bioactivity. Moreover, this system moves vials via magnetic levitation and includes process analytical technologies (PAT) to monitor the sublimation rate and temperature of every vial in the system, enabling the possibility of real time release and model-based feedback control to optimize drying conditions. The modular design of this continuous lyophilizer provides a direct link between laboratory and production-scale equipment, greatly simplifying the scale-up difficulty found in the traditional batch process.

Green Hydrogen produced via electrolysis may ultimately account for over 70% of Hydrogen demand (~327 Mt/yr) in the IEA Net-Zero by 2050 scenario [1]. While the exact market share may change with recent advances in geologically stimulated hydrogen production (orange hydrogen), lowering the cost of electrolysis could help the deep decarbonization of hard-to-abate sectors of our energy economy. At $2/kg H 2 ($0.06/kWh LHV) hydrogen could serve as an economical alternative fuel for long-haul trucking and feedstock for the ethanol and biofuels sector; while at the US Department of Energy’s (DoE) 2030 target of $1/kg H 2 ($0.03/kWh LHV) it would be poised to decarbonize the production of steel, cement, and ammonia, fuels for shipping and aviation, and industrial heat and power [2]. However, developing accurate estimates for the levelized cost of hydrogen (LCOH) from lab-scale results is difficult because it requires estimating contingent and variable costs (including siting and permitting, material costs, labor, electricity, depreciation, and tax incentives); these are highly dependent on economic and geopolitical factors, leading to a significant amount of extrapolation by researchers. While science focuses on technical targets such as Faradaic and energy efficiency, degradation rate, and current density as objective metrics, it’s important to clarify how these values directly affect LCOH. Here, we present a breakdown of how key performance metrics numerically translate to LCOH and develop a method for researchers to compare lab cell performance to the $1/kg H 2 target. We perform a sensitivity analysis on the H2A and H2A-Lite models developed by the National Renewable Energy Lab (NREL) to determine the relative contributions of cell efficiency (kWh/kg), degradation rate (mV/kh), current density (A/cm 2 ), capital cost ($/kW), and total Platinum (Pt) group metal content (mg/cm 2 ) to the LCOH while controlling for variable cost factors [3, 4]. Using these sensitivities, and the DoE’s technical targets for electrolysis, we develop a simplified metric, called the Performance Norm (N p ), as a measure of distance from the $1/kg H 2 target. We show how researchers can use the Performance Norm to (1) prioritize cell characteristics that will lead to more significant cost reduction at scale; (2) compare mechanically and technologically dissimilar cells; and (3) identify combinations of cell characteristics, beyond DoE technical targets, that could achieve low-cost green hydrogen production [5]. We compare this new indicator to existing metrics on multiple cells and stacks to show how a weighted, multivariate index provides a more tractable picture of an electrolysis system’s potential to achieve the $1/kg H 2 target. References [1] IEA (2019), The Future of Hydrogen , IEA, Paris, Licence: CC BY 4.0 [2] U.S. Department of Energy (2023). U.S. National Clean Hydrogen Strategy and Roadmap . [3] National Renewable Energy Laboratory (2008). H2A Production Model . [4] National Renewable Energy Laboratory (2017). H2A-Lite: Hydrogen Analysis Lite Production Model . [5] U.S. Department of Energy (2020). Electrolysis technical targets . Hydrogen and Fuel Cell Technologies Office.

Abstract Dynamometers are important tools for characterizing motors; however, they often produce inaccurate data due to misalignment between the motor and torque sensor. While typical alignment procedures are time-consuming, this paper proposes a dynamometer design that enables precision alignment with a single assembly. Rigid shaft couplers are used to align the motor with torque sensor, and the adjustable motor mount uses leveling sets and spherical washers to accommodate variability. Linear guides allow the rigid shaft coupler to be replaced with a flexible shaft coupler while maintaining precise alignment. Single-disc flexible shaft couplers were chosen for their linear dynamic behavior and high mechanical bandwidth. The linear guides’ precision was 3.7 times better than the disc coupler misalignment tolerance. The components’ load capacity were analyzed, resulting in safety factors of over 11. Finally, the resonance of the mounts was analyzed, giving a natural frequency 50% higher than the motor control frequency. When experimentally compared to a traditional dynamometer, this design resulted in mean attenuation of misalignment current oscillations of over 80%. When integrated with a motor and brake, the dynamometer had second-order linear dynamic behavior, with the analytically predicted natural frequency having a 5.6% error compared to the measured bandwidth.

Abstract Purpose Conventional shelf-freezing in pharmaceutical lyophilization suffers from batch variation and is potentially incompatible with emerging continuous lyophilization systems. This work presents a forced gas convective freezing chamber for suspended vials in cross-flow to improve the quality of the freezing process and meet the continuous lyophilization needs. Methods First, computational fluid dynamics simulations were performed to determine key process parameters. Then, physical chambers were built to meet these requirements. Sets of twenty 10R vials containing 3 mL of aqueous solution were frozen to characterize the per-vial heat transfer. Additionally, a novel nucleation technique was investigated where conditioned vials were exposed to an impulse of $$&lt;$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>&lt;</mml:mo> </mml:math> $$-$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mo>-</mml:mo> </mml:math> 30 $$^\circ $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mrow/> <mml:mo>∘</mml:mo> </mml:mmultiscripts> </mml:math> C gas. Finally, frozen vials were completely dried in 12 h in an attached vacuum chamber. Results The chambers conditioned vials from 25 $$^\circ $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mrow/> <mml:mo>∘</mml:mo> </mml:mmultiscripts> </mml:math> C to −1 $$^\circ $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mrow/> <mml:mo>∘</mml:mo> </mml:mmultiscripts> </mml:math> C in under 20 min, with final vial temperatures varying by less than 0.5 $$^\circ $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mrow/> <mml:mo>∘</mml:mo> </mml:mmultiscripts> </mml:math> C. The impulse technique induced nucleation in all vials within 30 s without significantly cooling them. After nucleation, the system accessed slow (0.05 g/min) and rapid (1.0 g/min) solidification rates, as well as post-solidification procedures including typical ramp and hold protocols. Dried vials had residual moisture below 2.5 wt% and showed no signs of collapse. Conclusions This freezing chamber was demonstrated to track gas temperature setpoints as low as −50 $$^\circ $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mrow/> <mml:mo>∘</mml:mo> </mml:mmultiscripts> </mml:math> C within ±1 $$^\circ $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mrow/> <mml:mo>∘</mml:mo> </mml:mmultiscripts> </mml:math> C and induce nucleation in all vials virtually simultaneously, enabling excellent control of the freezing process. The chamber’s cooling via forced convection and its available front and back faces make it compatible with integration into a continuous lyophilization system.

Three-dimensional secondary concentrators positioned at the entrance of solar thermal receivers, in tandem with point-focusing primary concentrators have been a subject of study and experimentation since the 1980s owing to their demonstrated ability to enhance the optical and thermal performance of Concentrating Solar Power (CSP) systems operating at high temperatures. They have been also proposed to reduce costs by rendering the overall optical system more tolerant of primary concentrator tracking and surface slope error. In certain CSP and thermal (CST) applications and configurations, the integration of 3D secondary concentrators is vital to meeting temperature and flux density requirements. This paper presents a comprehensive review of the prototypes that have been tested thus far, detailing their characteristics and enumerating the engineering, material science, testing, modeling and optimization challenges. Measures to address thermal management and related fabrication problems are discussed. The underlying theory of non-imaging optics and essential optical design considerations are summarized. Finally, the ongoing developments of reflective materials suitable for high-temperature applications in 3D secondary concentrators are examined, along with an evaluation of the most promising candidates. Priorities for filling research gaps and comprehensive design approaches are identified (based on testing of prototypes reported in the literature).

The Anthropocene has ushered in unprecedented environmental challenges, with invasive seaweed blooms emerging as a critical yet understudied facet of climate change. These blooms, driven by nutrient runoff and oceanic alterations, disrupt ecosystems, threaten biodiversity, and impose economic and public health burdens on coastal communities. However, invasive seaweeds also present an opportunity as a sustainable resource. This study explores the valorization of Sargassum spp. for agricultural applications, focusing on the development of biodegradable bioplastics and biostimulants. Field trials demonstrated the effectiveness of Marine Symbiotic® Sargassum-derived biostimulant in distinct agricultural contexts. In the Dominican Republic, trials on pepper crops showed significant improvements, including a 33.26% increase in fruit weight, a 21.94% rise in fruit set percentage, a 45% higher yield under high-stress conditions, and a 48.42% reduction in fruit rejection compared to control. In Colombia, trials across four leafy green varieties revealed biomass increases of up to 360%, a 50% reduction in synthetic input dependency, and enhanced crop coloration, improving marketability. Additionally, Sargassum-based biofilms exhibited favorable mechanical properties and biodegradability, offering a sustainable alternative to conventional agricultural plastics. Carbon credit quantification revealed that valorizing Sargassum could prevent up to 89,670 tons of CO2-equivalent emissions annually using just one Littoral Collection Module® harvesting system, while biostimulant application enhanced carbon sequestration in crops. These findings underscore the potential of invasive seaweed valorization to address multiple climate challenges, from reducing plastic pollution and GHG emissions to enhancing agricultural resilience, thereby contributing to a sustainable Blue Economy and aligning with global sustainability goals.

In a future where a large portion of power will be supplied by highly intermittent sources such as solar- and wind-power, energy storage will form a crucial part of the power mix ensuring that there is enough flexibility in the system to cope with the intermittency. With further development of pumped storage hydro constrained by the lack of remaining suitable topography, a novel Subsea Pumped Hydro Storage concept has emerged as a promising solution to utilize the ocean space for large-scale energy storage. While previous publications address thermodynamic efficiency limits, there is a notable lack of research on turbine selection, design, and cost estimation based on best practices. This paper presents a comprehensive overview of current state-of-the-art subsea engineering and its significant achievements pioneered by the oil and gas industry. This paper introduces a robust methodological framework for calculating the costs of concrete SPHS tanks, factoring in longevity and best installation practices for structures designed to endure for half a century. The results indicate that with an optimized design, the cost of an SPSH concrete storage tank is approximately $0.15/Wh. This work lays the groundwork for future advancements in SPHS, building on the substantial progress within subsea engineering over recent decades, and marks a significant step towards realizing the potential of this concept in the renewable energy landscape.

We provide the mechanical and dynamical requirements for a robotic finger capable of performing thirty diverse everyday tasks. To match these requirements, we present a finger design based on series-elastic actuation that we call the everyday finger. Our focus is to make the fingers as compact as possible while achieving the desired performance. We evaluated everyday fingers by constructing a two-finger robotic hand that was tested on various performance parameters and tasks like picking and placing dishes in a rack, picking thin and flat objects like paper and delicate objects such as strawberries. Videos are available at the project website: https://sites.google.com/view/everydayfinger.

Abstract The majority of hospitalized patients require the insertion of a catheter as part of their medical treatment. For catheters to be connected to external devices, barbed connectors are often employed. If this connection is ever disrupted, a direct channel from the environment to the patient's internal body may be introduced, leading to a life-threatening emergency. Current methods of securing catheter tubes to connectors have various limitations that have prevented their widespread adoption in medical settings, ranging from low ease of use to poor geometric compatibility. The authors present a device, called the Catheter Connector Clamp (C-3), shown in Fig. 1 that will securely clamp multisize catheter tubes to existing barbed connectors to increase the security and repeatability of the connection. The authors also propose a method for comparing the effectiveness of current catheter connection solutions to their C-3 design using maximum pull-off force. On silicone medical tubing, the C-3 clamp performed more than twice as well as friction alone (2.09 times more), and 25% better than the hospital gold-standard taped connection.

Abstract Popliteal artery entrapment syndrome (PAES) is a condition affecting blood flow in the back of the leg, which can have a significant impact on the patient's life. It is often misdiagnosed due to a lack of standardized procedures and quantifiable diagnostic criteria. To facilitate easier and more accurate diagnosis of this syndrome, we have designed and built an initial prototype of a device that provides adjustable resistance during plantar-flexion of the patient's ankle while quantifying force generated and ankle range of motion. The device will be used while the physician observes blood flow through the popliteal artery in the back of the knee using an ultrasound. The device provides a convenient and ergonomic solution for patients and physicians, which helps improve the accuracy of PAES diagnosis and allows physicians to further study this condition.

We provide the mechanical and dynamical requirements for a robotic finger capable of performing a large number of everyday tasks. To match these requirements, we present a novel actuator and finger design, the everyday finger, that comes close to many characteristics of the human fingers. In particular, we focus on minimizing the size of components to get proper performance without sacrificing compactness. A robotic hand that uses two Everyday fingers demonstrated an 80% success rate in picking up and placing dishes in a rack, and the ability to pick up flat objects like napkins and delicate ones like strawberries. Videos are available at the project website: https://sites.google.com/view/everydayfinger.

Abstract Fluid systems often require complex and plentiful valving which route a variety of input and output streams according to a system state. Many valves and actuators can create additional points of failure, maintenance, and cost. Multi-port selector valves are one solution which simplify complex configurations but are designed for a specific application. This custom design can create inflexibility and increased manufacturing cost when the user wishes to consider architectural changes or alternative applications. Modular, reconfigurable systems exist in fluid power systems (hydraulics, pneumatics), but few exist for larger, bulk flow applications. To address the issue of reconfigurability and simplicity within complex fluid valve architectures, we consider how one would design a single-actuator, reprogrammable, mechanical logic valve. We consider design requirements for such a system, various strategies and concepts, and converge on exploring the design of a multiport, rotary valve. Geometric layout and performance models are proposed and parametrically analyzed to understand the design space, trends, and tradeoffs. This work lays initial foundation and exploration of modular, mechanically reconfigurable, rotary valves. We envision this design and architectural toolbox to be metaphorically similar to common, easy-to-assemble and reconfigure, standardized materials such as 80/20, push-to-connect fittings, and even Legos - but instead, with application to valve geometries.

A method of manufacturing an electrochemical cell includes transferring an anode semi-solid suspension to an anode compartment defined at least in part by an anode current collector and an separator spaced apart from the anode collector. The method also includes transferring a cathode semi-solid suspension to a cathode compartment defined at least in part by a cathode current collector and the separator spaced apart from the cathode collector. The transferring of the anode semi-solid suspension to the anode compartment and the cathode semi-solid to the cathode compartment is such that a difference between a minimum distance and a maximum distance between the anode current collector and the separator is maintained within a predetermined tolerance. The method includes sealing the anode compartment and the cathode compartment.

A hose connection system comprises a body including an internal cavity and a port in fluid communication with a portion of the internal cavity. In addition, the system comprises a hose end fitting positioned in the cavity. The hose end fitting includes an inner tubular member and an outer tubular member concentrically disposed about the inner tubular member. The outer tubular member includes a plurality of circumferentially spaced axial slits. Further, the system comprises a plurality of wedge members arranged circumferentially about the outer tubular member. Still further, the system comprises an annular piston movably disposed within the internal cavity of the body. An end of the piston has an inner frustoconical surface that slidingly engages the plurality of wedge members. The piston is configured to move axially through the body and compress the wedge members and the outer tubular member radially inward.