Benchtop Testing Research Articles

A novel strain-based bone-fracture healing algorithm is able to predict a range of healing outcomes.

Fracture healing is a complex process which sometimes results in non-unions, leading to prolonged disability and high morbidity. Traditional methods of optimising fracture treatments, such as in vitro benchtop testing and in vivo randomised controlled trials, face limitations, particularly in evaluating the entire healing process. This study introduces a novel, strain-based fracture-healing algorithm designed to predict a wide range of healing outcomes, including both successful unions and non-unions. The algorithm uses principal strains as mechanical stimuli to simulate fracture healing in response to local mechanical environments within the callus region. The model demonstrates good agreement with experimental data from ovine metatarsal osteotomies across six fracture cases with varying gap widths and inter-fragmentary strains, replicates physiological bony growth patterns, and is independent of the initial callus geometry. This computational approach provides a framework for developing new fracture-fixation devices, aid in pre-surgical planning, and optimise rehabilitation strategies.

Integrated System Modal and Mistuning Identification for Integrally Bladed Rotors

Abstract The safety of Integrally Bladed Rotors (IBRs) is often assessed through bench-level vibration tests to measure amplification factors and back-out sector frequency deviations via mistuning identification (ID) algorithms. This process is usually composed of two separate steps. First, a system ID step is completed to identify system modal data. Then, this data is input into mistuning ID algorithms. Errors in identified modal data will then propagate to produce errors in the system's predicted mistuning. Obtaining robust mistuning estimates then requires larger quantities of accurate modal data. This effort seeks to attain accurate mistuning data by coupling the system and mistuning ID steps into a more parallel, versus serial, process that is capable of identifying many system modes. An iterative Polyreference-Least Squares Complex Frequency- domain (P-LSCF) algorithm finds modal data, and a mistuning ID algorithm obtains mistuning data at each iteration. An outlier detection method is proposed to remove spurious modes that cause erroneous mistuning results. Then, a weighted, least-squares regression approach is employed to remove the impact of sector-specific outlier data. This method reduces errors in identified mistuning parameters from the Fundamental Mistuning Model (FMM) ID algorithm. Furthermore, the approaches eliminate the need for users to determine true versus spurious system modes in each iteration of the P-LSCF algorithm, thus removing ambiguity. The developed approaches are tested on simulated and bench-top test data. Results show the efficacy of the developed approaches and their ability to account for uncertainty in mistuning parameters.

229 Awardee Talk: The quest for an ideal in-field embryo evaluation tool in cattle: Opportunities and challenges

Abstract Accurately evaluating bovine embryos to select the most viable ones for transfer and successful pregnancy has been a challenge since embryo transfer began in cattle over six decades ago. Despite more than 3,100 peer-reviewed studies on bovine embryo evaluation published in PubMed from 1964 to 2023, there is still no consensus or gold standard method for assessing their developmental potential. The evaluation “problem” in assisted reproduction extends beyond embryos to gametes as well. Numerous microscopic techniques (e.g., differential interference contrast, electron, fluorescent, time-lapse, and artificial intelligence-based microscopy) and non-microscopic methodologies (e.g., genomics, transcriptomics, epigenomics, proteomics, metabolomics, and nuclear magnetic resonance) have been tested to find an embryo evaluation technique superior to morphological evaluation. While many of these research tools can accurately determine embryo quality and viability, most are invasive, expensive, labor-intensive, technically complex, and time-consuming, making them impractical for in-field embryo evaluation. Employing complex methods like RNA sequencing, SNP chips, mass spectrometry, and multiphoton microscopy at thousands of embryo production and collection facilities is unrealistic, no matter how accurate they may be. Therefore, future research should focus on innovating field-friendly, simple benchtop tests using existing findings, particularly from omics-based research methodologies. Time-lapse monitoring and artificial intelligence-based automated image analysis also potentially provide accurate embryo evaluation. However, further research is necessary to develop economically feasible options for in-field applications. Our recent work has examined possible applications of nuclear magnetic resonance (NMR) imaging, label-free microscopy, particularly holographic microscopy techniques like gradient light interference microscopy (GLIM), spatial light interference microscopy (SLIM), and multiphoton holographic microscopy in IVF labs. The ideal embryo evaluation tool should be accurate, objective, non-invasive, affordable, and simple enough for widespread adoption by embryo production and collection facilities worldwide. Under current circumstances, it is doubtful that transcriptomics, proteomics, metabolomics, GLIM, SLIM, NMR, multiphoton holographic microscopy, and similar techniques can be directly used for in-field embryo evaluation. However, biomarkers identified by these methodologies could be used for in-field embryo evaluation by devising simple, affordable benchtop techniques. Further investigation on time-lapse microscopy (TLM) and AI-based automated image processing may make these methods more affordable and potentially adoptable by the masses. There is great potential for these methodologies to become widely used, provided they can be made more economically viable. In conclusion, the next generation of microscopy capable of providing objective markers for gamete and embryo quality is on the horizon.

A Modified Benchtop Test Method to Measure the Movements of Intervertebral Body Fusion Devices

Abstract This study developed and evaluated a new benchtop test method to measure the movements of different designs of intervertebral body fusion devices (IBFDs) under cyclic loads. The experimental method simulates and evaluates the movement resistance of intervertebral cages under flexion-extension cyclic loads experienced by the lumbar spine. The present method modifies a method developed previously and offers a possibility to be more clinically relevant and robust. This is because it allowed for closer achievement of levels of IBFD rotation reported in the literature and introduced the ability to control the flexion-extension movement and, consequently, the rotation of the cage more precisely. Polyurethane foam blocks were used as the bone substitute material. Optical and contactless displacement measurements were performed using a robust six degrees of freedom measuring system (OptiTrack) to evaluate the movements of the IBFD during testing. The results obtained by applying the new benchtop method showed greater sensitivity in capturing the implant movements in all directions measured, with magnitude significantly superior from Ribeiro et al. (2022). A test method to measure the movements of different IBFD designs was modified to better simulate and control the lumbar spine flexion-extension movements. The proposed benchtop methodology can evaluate the IBFD movements in all directions to more efficiently discriminate in a potentially standardized test the efficacy of different IBFD designs.

Management of Vesicovaginal Fistula in Lower-Resource Settings: A Novel Device for Collection and Drainage of Urine

Abstract Treatment of vesicovaginal fistula (VVF) is currently limited to surgical repair that is costly and sparsely available and requires intervention from trained specialists, preventing patients in lower-resource settings from receiving effective care. As those who remain untreated continue to experience severe vaginal urinary leakage, an affordable, easy-to-use device that discreetly contains and redirects unwanted leakage of fluids would temporarily alleviate the social distress associated with VVF until patients can afford to present for treatment. We present a novel device to mitigate urinary leakage caused by VVF using a vaginal cup, which allows for the funneling and rerouting of urine into an external drainage bag, to be released at a user's convenience. For patients who cannot afford surgery, our device helps manage their symptoms so that they can reintegrate into society and no longer face the harrowing stigma of their family and society. We demonstrate the effectiveness of our device through preliminary benchtop testing, using a non-living vaginal model to verify leak-free retainment of the device under varying pressure conditions. Preliminary results indicate that the device displayed no circumferential leakage, and the internal displacement of the cup was within the allotted range of 5 mm for applied hydrostatic pressures up to 150 cm H2O.

First results from the RD53 ATLAS pixel production readout ASIC (ITkPixV2) for HL-LHC

The Phase-2 upgrades of ATLAS and CMS for the High-Luminosity LHC (HL-LHC), require a new tracker with robust readout electronics capable of withstanding extreme radiation (1 Grad), a high hit rate (3 GHz/cm2), and a high data rate readout (5 Gb/s). In a joint effort between ATLAS and CMS, pixel detector readout chips have been designed by the RD53 collaboration in 65 nm CMOS technology. Based on a half-sized demonstrator (RD53A), two chip variants were designed for ATLAS and CMS, respectively. The ATLAS pre-production readout chip, ITkPixV1, was characterised in detail, and informed by the results, the final ATLAS pixel readout chip, ITkPixV2, has been designed, submitted, and the first wafers were received in July 2023. This contribution provides an overview of the characterisation measurements performed on the ITkPixV2 chip so far, focusing on bench-top testing of chip functionality, and first results of X-ray irradiation studies to assess the radiation tolerance of the chip.

Optical benchtop evaluation of special intraocular lens optics

Intraocular lenses (IOL) featuring complex optical designs can pose achallenge in understanding their performance, which may hinder making an informed decision when selecting suitable lenses for patients. This underlines the importance of collecting optical quality data of IOLs and making them available. The deployment of benchtop systems for IOL testing offers not only insights into the design features of various IOL solutions but also provides aplatform for objective comparisons of special optics designs, including information about their susceptibility to photic phenomena. Recent advances in IOL testing have improved the ability to predict functional effects on visual acuity and contrast sensitivity from objective optical quality metrics. This, for instance, can be used to study monofocal lenses and the impact of asphericity on vision and IOLs tolerance to misalignment. Monofocal-plus IOLs consistently show only aslight improvement in the depth of focus when tested on the optical bench and in clinical settings. Although the pupil dependence found in this technology may limit the advantages of monofocal-plus over standard monofocal technology to extend the range of vision, it is the key to reduce photic phenomena. Refractive and diffractive extended depth of focus (EDOF) IOLs can effectively enhance intermediate vision, with the latter offering aslightly broader depth of focus but potentially increasing the risk of dysphotopsia. However, the limitation of EDOF IOLs is that they often fail to deliver spectacle independence for reading, which can be overcome by trifocal technology. Still, the available trifocal IOLs differ in their location of intermediate and near foci and the susceptibility to produce glare effects. Therefore, the knowledge from optical benchtop testing of IOLs can support optimizing the IOL selection by aligning the patient's visual needs with the IOL's properties, setting the right expectations, and assessing the risk profile for the occurrence of photic phenomena, potentially leading to improved decision-making.

Development and Validation of New LC-MS/MS Bioanalytical Method of Tremelimumab in Rat Plasma by Using Nivolumab as Internal Standard and Its Application with Pharmacokinetic Studies

Nivolumab was decided to be used as the IS. To separate the drugs, an isocratic mobile phase of acetonitrile (ACN): Ammonium formate containing formic acid (70:30) was adopted and delivered at 1-mL/min, along with a 150 x 4.6 mm x 3.5 μm Alliance, e2695 Luna Phenyl Hexyl column. Drug and IS, both of which display proton adducts approximately m/z 146.3685 to 120.0638 and m/z 143.7695 to 76.7964, might be detected simultaneously using MRM-positive modalities. Over a linearity level of 2.00 to 40.00 ng/mL, the method had a correlation value (r2) of 0.99977. The accuracy and precision of this method during the day ranged from 89.85 to 102.89% and 0.19 to 2.81%, respectively. Tremelimumab was reported to remain stable during three freeze-thaw cycles, benchtop tests, and postoperative stability studies. Cmax and Tmax values were acquired directly from experimental data. Cmax and Tmax averaged 18.024 ng/mL and 6 hours, respectively. At t1/2 of 18 hours, plasma levels began to fall. The obtained AUC024 and AUC0 values were 257 and 257 ng h/mL, respectively.

Application of Compressible Carbon in Cement to Mitigate Cement Pore Pressure Reduction and Improve Cement Bonding

Summary A quality cement job is essential to ensure long-term zonal isolation in oil/gas and carbon storage wells. This may be affected by the cement hydration process, during which water is consumed, causing pore pressure reduction and shrinkage, which increases the risk of fluid/gas invasion, formation of microannuli, and even the risk of shear bond strength reduction. In this paper, we present the application of compressible carbon (CC) particles as a cement additive to mitigate cement pore pressure reduction and improve zonal isolation. We designed cement formulations with CC and evaluated them using API standard tests and industry-wide recognized tests to ensure they met functional requirements for well cementing, such as mixability, thickening time, rheology, compressive strength development, fluid loss, and free water. The concept is as follows: When cement is pumped into an annulus, the CC particles will compress under hydrostatic pressure. When the cement is hydrating, the CC will expand to mitigate the pore pressure reduction. To validate the proof of concept, we developed a benchtop high-pressure, high-temperature setup and a pilot-scale test setup. A cement formulation with 9% CC by volume was found to be stable and have controllable performance properties such as thickening time, fluid loss, and free water. We also designed and tested a control slurry without CC for comparison. Both the benchtop and pilot-scale tests demonstrated that adding CC into the cement formulation mitigated the pore pressure reduction during cement hydration. This may reduce the risk of fluid/gas invasion that could result in migration in the set cement. Comparing the cement containing carbon with the control system without carbon, the gas permeability was reduced. The bond strength obtained from shear bond tests improved significantly, which may reduce the risk of debonding and be an indication of the reduction of shrinkage. In addition, a better hydraulic seal was found in one test, but further investigation is needed. Similar mechanical properties such as compressive strength were measured for both cements with and without CC. The data showed that adding CC does not have a negative impact on the hardened cement properties. In fact, adding CC decreased Poisson’s ratio slightly. In this paper, we present the results of proof-of-concept testing for the novel application of CC in cement to improve zonal isolation by mitigating pore pressure reduction. We also present new benchtop and pilot-scale experimental setups to measure pore pressure changes during cement hydration.

Design and Evaluation of an Eye Mountable AutoDALK Robot for Deep Anterior Lamellar Keratoplasty.

Partial-thickness corneal transplants using a deep anterior lamellar keratoplasty (DALK) approach has demonstrated better patient outcomes than a full-thickness cornea transplant. However, despite better clinical outcomes from the DALK procedure, adoption of the technique has been limited because the accurate insertion of the needle into the deep stroma remains technically challenging. In this work, we present a novel hands-free eye mountable robot for automatic needle placement in the cornea, AutoDALK, that has the potential to simplify this critical step in the DALK procedure. The system integrates dual light-weight linear piezo motors, an OCT A-scan distance sensor, and a vacuum trephine-inspired design to enable the safe, consistent, and controllable insertion of a needle into the cornea for the pneumodissection of the anterior cornea from the deep posterior cornea and Descemet's membrane. AutoDALK was designed with feedback from expert corneal surgeons and performance was evaluated by finite element analysis simulation, benchtop testing, and ex vivo experiments to demonstrate the feasibility of the system for clinical applications. The mean open-loop positional deviation was 9.39 µm, while the system repeatability and accuracy were 39.48 µm and 43.18 µm, respectively. The maximum combined thrust of the system was found to be 1.72 N, which exceeds the clinical penetration force of the cornea. In a head-to-head ex vivo comparison against an expert surgeon using a freehand approach, AutoDALK achieved more consistent needle depth, which resulted in fewer perforations of Descemet's membrane and significantly deeper pneumodissection of the stromal tissue. The results of this study indicate that robotic needle insertion has the potential to simplify the most challenging task of the DALK procedure, enable more consistent surgical outcomes for patients, and standardize partial-thickness corneal transplants as the gold standard of care if demonstrated to be more safe and more effective than penetrating keratoplasty.

Structural tuning of anisotropic mechanical properties in 3D-Printed hydrogel lattices

We investigated the ability to tune the anisotropic mechanical properties of 3D-printed hydrogel lattices by modifying their geometry (lattice strut diameter, unit cell size, and unit cell scaling factor). Many soft tissues are anisotropic and the ability to mimic natural anisotropy would be valuable for developing tissue-surrogate “phantoms” for elasticity imaging (shear wave elastography or magnetic resonance elastography). Vintile lattices were 3D-printed in polyethylene glycol di-acrylate (PEGDA) using digital light projection printing. Two mechanical benchtop tests, dynamic shear testing and unconfined compression, were used to measure the apparent shear storage moduli (G′) and apparent Young's moduli (E) of lattice samples. Increasing the unit cell size from 1.25 mm to 2.00 mm reduced the Young's and shear moduli of the lattices by 91% and 85%, respectively. Decreasing the strut diameter from 300 μm to 200 μm reduced the apparent shear moduli of the lattices by 95%. Increasing the geometric scaling ratio of the lattice unit cells from 1.00 × to 2.00 × increased mechanical anisotropy in shear (by a factor of 3.1) and in compression (by a factor of 2.9). Both simulations and experiments show that the effects of unit cell size and strut diameter are consistent with power law relationships between volume fraction and apparent elastic moduli. In particular, experimental measurements of apparent Young's moduli agree well with predictions of the theoretical Gibson-Ashby model. Thus, the anisotropic mechanical properties of a lattice can be tuned by the unit cell size, the strut diameter, and scaling factors. This approach will be valuable in designing tissue-mimicking hydrogel lattice-based composite materials for elastography phantoms and tissue engineered scaffolds.

Prosthetic Limb Attachment via Electromagnetic Attraction Through a Closed Skin Envelope.

Current socket-based methods of prosthetic limb attachment are responsible for many of the dominant problems reported by persons with amputation. In this work, we introduce a new paradigm for attachment via electromagnetic attraction between a bone-anchored ferromagnetic implant and an external electromagnet. Our objective was to develop a design framework for electromagnetic attachment, and to evaluate this framework in the context of transfemoral amputation. We first used inverse dynamics to calculate the forces required to suspend a knee-ankle-foot prosthesis during gait. We then conducted cadaveric dissections to inform implant geometry and design a surgical methodology for covering the implant. We also developed an in silico framework to investigate how electromagnet design affects system performance. Simulations were validated against benchtop testing of a custom-built electromagnet. The physical electromagnet matched simulations, with a root-mean-square percentage error of 4.2% between measured and predicted forces. Using this electromagnet, we estimate that suspension of a prosthesis during gait would require 33 W of average power. After 200 and 1000 steps of simulated walking, the temperature at the skin would increase 2.3 °C and 15.4 °C relative to ambient, respectively. Our design framework produced an implant and electromagnet that could feasibly suspend a knee-ankle-foot prosthesis during short walking bouts. Future work will focus on optimization of this system to reduce heating during longer bouts. This work demonstrates the initial feasibility of an electromagnetic prosthetic attachment paradigm that has the potential to increase comfort and improve residual limb health for persons with amputation.

A Comprehensive Study on Implant Stability Quotient (ISQ) in View of Resonance Frequency and Spectrum Analysis.

To investigate how well an implant stability quotient (ISQ) represents resonance frequency. Benchtop experiments on standardized samples that replicated a mandibular premolar site were conducted to correlate an ISQ value and a resonance frequency to synthetic bone density and an incremental insertion torque; then, a frequency spectrum analysis was performed to check the validity of the resonance frequency analysis (RFA). Brånemark Mk III implants (4 × 11.5 mm; Nobel Biocare) were placed in Sawbones test models of five different densities (40, 30, 40/20, 20, and 15 PCF). An incremental insertion torque was recorded during implant placement. To perform stability measurements, the test models were partially clamped in a vise (unclamped volume: 10 × 20 × 34 mm). A MulTipeg (Integration Diagnostics) was attached to the implants, and a Penguin (Integration Diagnostics) RFA measured ISQ. Simultaneously, the MulTipeg motion was monitored via a laser Doppler vibrometer and processed by a spectrum analyzer to obtain the resonance frequency. Tightness of the clamp was adjusted to vary the resonance frequency. A statistical analysis produced a linear correlation coefficient (R) among the measured ISQ, resonance frequency, and incremental insertion torque. The resonance frequency had high correlation to the incremental insertion torque (R = 0.978), confirming the validity of using RFA for this study. Measured ISQ data were scattered and had low correlation to the resonance frequency (R = 0.214) and the incremental insertion torque (R = 0.386). The spectrum analysis revealed the simultaneous presence of multiple resonance frequencies. For the designed benchtop tests, resonance frequency does indicate implant stability in view of Sawbones density and incremental insertion torque. However, ISQ measurements do not correlate to the resonance frequency and may not reflect the stability when multiple resonance frequencies are present simultaneously.

Thermal Characterization and Preclinical Feasibility Verification of an Accessible, Carbon Dioxide-Based Cryotherapy System.

To investigate the potential of an affordable cryotherapy device for the accessible treatment of breast cancer, the performance of a novel carbon dioxide-based device was evaluated through both benchtop testing and an in vivo canine model. This novel device was quantitatively compared to a commercial device that utilizes argon gas as the cryogen. The thermal behavior of each device was characterized through calorimetry and by measuring the temperature profiles of iceballs generated in tissue phantoms. A 45 min treatment in a tissue phantom from the carbon dioxide device produced a 1.67 ± 0.06 cm diameter lethal isotherm that was equivalent to a 7 min treatment from the commercial argon-based device, which produced a 1.53 ± 0.15 cm diameter lethal isotherm. An in vivo treatment was performed with the carbon dioxide-based device in one spontaneously occurring canine mammary mass with two standard 10 min freezes. Following cryotherapy, this mass was surgically resected and analyzed for necrosis margins via histopathology. The histopathology margin of necrosis from the in vivo treatment with the carbon dioxide device at 14 days post-cryoablation was 1.57 cm. While carbon dioxide gas has historically been considered an impractical cryogen due to its low working pressure and high boiling point, this study shows that carbon dioxide-based cryotherapy may be equivalent to conventional argon-based cryotherapy in size of the ablation zone in a standard treatment time. The feasibility of the carbon dioxide device demonstrated in this study is an important step towards bringing accessible breast cancer treatment to women in low-resource settings.

Computed Tomography Geometry of Extremely Undersized SAPIEN 3 Transcatheter Aortic Valves With Balloon Overfilling

Overfilling the balloon-expandable Sapien 3/Ultra (S3) transcatheter heart valves in undersized aortic valve anatomies is associated with favorable outcomes. The expansion of S3 valves beyond nominal values is feasible on benchtop testing. Still, a dearth of information exists on the actual valve area achieved when these valves are filled beyond nominal volumes. We herein assess post-transcatheter aortic valve replacement (TAVR) computed tomography (CT) derived geometry of overfilled, extremely undersized balloon-expandable transcatheter heart valves. A total of 23 patients (mean age 76±7.2 years, 17.4% female) treated had annular undersizing: 10.3±2.0% for 23mm, 7.8±4.8% for 26mm and 12.3±6.3% for 29mm. The mean volumes added to 23mm, 26mm, and 29mm S3 valves were 1.9±0.3 mL, 2.2±0.7mL, 3.2 ±1.3 mL, respectively. CT analysis at 30 days found that no valve achieved an expansion index >1 at the mid-frame portion, i.e., greater than the respective valve’s nominal valve area, but 29mm S3 had an expansion index >1 at inflow and outflow. Aortic valve gradients were favourable, and there was no moderate/severe PVL or transvalvular regurgitation at 30-day follow-up. We hypothesize that the approach of undersizing for annular anatomies and overfilling the balloon may achieve more optimal valve expansion.

479 BrainPacer: Wireless Battery-Free Neuromodulator Embedded in a Dural Graft

INTRODUCTION: Neuromodulation represents an emerging realm of disruptive technologies for brain/spine disorders with potential applications across disease states, including neurodegenerative, neoplastic, epilepsy, trauma and vascular disorders. However, current implants have limitations inherent to the use of wires, batteries that need replacement, infection, and implant failure that have hindered wider adoption. METHODS: A 100 µm-thick, biocompatible, flexible, and transparent Parylene/PDMS substrate was used. In vivo validation (120 stimulation bursts, 10 pulses, 4 rats and 4 implants) was pursued using motor cortex stimulation after identification of the hindlimb representation via direct cortical stimulation. Hindlimb motion and reliability of stimulation and movement were detected via a video analysis software. A comparison of efficiency was conducted between the proposed dura substitute method and conventional direct stimulation method. RESULTS: Benchtop testing demonstrates reliable monophasic voltage pulses with an amplitude of 20V that can be subsequently regulated. Stimulation through the dura substitute results in reduced efficiency by 60% due to current loss but it offers the same reliability, triggering a motor response at each stimulation onset with an average limb deflection of 5.2 ± 2.986 mm with 99% confidence level. At least 30 seconds of recordings were obtained in each animal at a stimulation frequency of 1 Hz. CONCLUSIONS: We designed, validated and tested both a novel wireless and battery-free implant and a novel embodiment for placement with revolutionary potential. The implant triggers motor response through an FDA-approved dura substitute, without contacting the cortical surface. Studies in free-moving animals for chronic response studies are ongoing.

TABERNACL: Temporary Hemodynamic Stabilization In Vivo.

Acute aortic regurgitation is life-threatening with few nonsurgical options for immediate stabilization. We propose Trans-Aortic Balloon to Ease Regurgitation Applying Counter-Pulsation (TABERNACL), a simple, on-table temporary valve using commercially available equipment to temporize acute severe aortic regurgitation. We hypothesize that an appropriately sized commercial balloon dilatation catheter-straddling the aortic annulus and connected to a counterpulsation console-can serve as a temporizing valve to restore hemodynamic stability in acute aortic regurgitation. We performed benchtop testing of valvuloplasty, angioplasty, and sizing balloons as counterpulsation balloons. TABERNACL was assessed in vivo in a porcine model of acute aortic regurgitation (n=8). We also tested a static undersized, continuously inflated transvalvular balloon as a spacer intended physically to obstruct the regurgitant orifice. Benchtop testing identified that Tyshak II and PTS sizing (NuMed Braun) balloon catheters performed adequately as temporary valves (ie, complete inflation and deflation with each cycle) and resisted fatigue, in contrast to others. When TABERNACL was used in the acute severe regurgitation animals, there was immediate hemodynamic improvement, with a significant 35% increase in diastolic aortic pressure by 16 mm Hg ([95% CI, 7-25] P=0.0056), 34% reduction in left ventricular end-diastolic pressure by -7 mm Hg ([95% CI, -10 to -5] P=0.0006), improvement in the aortic diastolic index by 0.28 ([95% CI, 0.18-0.39] P=0.0009), and reversal of electrocardiographic myocardial ischemia. As an alternative, static balloon inflation across the aortic valve stabilized regurgitation hemodynamics at the expense of a new aortic gradient and caused excessive ectopy from balloon movement in the left ventricular outflow tract. TABERNACL improves hemodynamics and reduces coronary ischemia by electrocardiography in animals with acute severe aortic regurgitation. TABERNACL valves obstruct the diastolic regurgitant orifice without systolic obstruction. This may prove a lifesaving bridge to definitive valve replacement therapy.

Development of Quasi-Passive Back-Support Exoskeleton with Compact Variable Gravity Compensation Module and Bio-Inspired Hip Joint Mechanism.

The back support exoskeletons have garnered significant attention to alleviate musculoskeletal injuries, prevalent in industrial settings. In this paper, we propose AeBS, a quasi-passive back-support exoskeleton developed to provide variable assistive torque across the entire range of hip joint motion, for tasks with frequent load changes. AeBS can adjust the assistive torque levels while minimizing energy for the torque variation without constraining the range of motion of the hip joint. To match the requisite assistance levels for back support, a compact variable gravity compensation module with reinforced elastic elements is applied to AeBS. Additionally, we devised a bio-inspired hip joint mechanism that mimics the configuration of the human hip axis to ensure the free body motion of the wearer, significantly affecting assistive torque transmission and wearing comfort. Benchtop testing showed that AeBS has a variable assistive torque range of 5.81 Nm (ranging from 1.23 to 7.04 Nm) across a targeted hip flexion range of 135°. Furthermore, a questionnaire survey revealed that the bio-inspired hip joint mechanism effectively facilitates the transmission of the intended assistive torque while enhancing wearer comfort.

Pyrylium- and Pyridinium-Based Ionic Liquids as Friction Modifiers for Greases.

The use of ionic liquids (ILs) as lubricants or additives has been studied extensively over the past few decades. However, the ILs considered for lubricant applications have been part of a limited structural class of phosphonium- or imidazolium-type compounds. Here, new pyrylium- and pyridinium-based ILs bearing long alkyl chains were prepared and evaluated as friction- and wear-reducing additives in naphthenic greases. The physical properties of the synthetic ILs and additized naphthenic grease were measured. The tribological performance of the greases was measured by using standard benchtop tests. The addition of ILs was detrimental to wear, causing an increase in the amount of material removed by sliding relative to the base greases in most cases. In contrast, the friction performance improved under nearly all conditions tested due to the IL additives. The compatibility of the synthetic ILs with the naphthenic greases and its potential influence upon miscibility and tribological performance are tentatively proposed to be a result of the molecular structure.

Enzymatic digestion does not compromise sliding-mediated cartilage lubrication

Articular cartilage's remarkable low-friction properties are essential to joint function. In osteoarthritis (OA), cartilage degeneration (e.g., proteoglycan loss and collagen damage) decreases tissue modulus and increases permeability. Although these changes impair lubrication in fully depressurized and slowly slid cartilage, new evidence suggests such relationships may not hold under biofidelic sliding conditions more representative of those encountered in vivo. Our recent studies using the convergent stationary contact area (cSCA) configuration demonstrate that articulation (i.e., sliding) generates interfacial hydrodynamic pressures capable of replenishing cartilage interstitial fluid/pressure lost to compressive loading through a mechanism termed tribological rehydration. This fluid recovery sustains in vivo-like kinetic friction coefficients (µk<0.02 in PBS and <0.005 in synovial fluid) with little sensitivity to mechanical properties in healthy tissue. However, the tribomechanical function of compromised cartilage under biofidelic sliding conditions remains unknown. Here, we investigated the effects of OA-like changes in cartilage mechanical properties, modeled via enzymatic digestion of mature bovine cartilage, on its tribomechanical function during cSCA sliding. We found no differences in sliding-driven tribological rehydration behaviors or µk between naïve and digested cSCA cartilage (in PBS or synovial fluid). This suggests that OA-like cartilage retains sufficient functional properties to support naïve-like fluid recovery and lubrication under biofidelic sliding conditions. However, OA-like cartilage accumulated greater total tissue strains due to elevated strain accrual during initial load application. Together, these results suggest that elevated total tissue strains—as opposed to activity-mediated strains or friction-driven wear—might be the key biomechanical mediator of OA pathology in cartilage. Statement of SignificanceOsteoarthritis (OA) decreases cartilage's modulus and increases its permeability. While these changes compromise frictional performance in benchtop testing under low fluid load support (FLS) conditions, whether such observations hold under sliding conditions that better represent the joints’ dynamic FLS conditions in vivo is unclear. Here, we leveraged biofidelic benchtop sliding experiments—that is, those mimicking joints’ native sliding environment—to examine how OA-like changes in mechanical properties effect cartilage's natural lubrication. We found no differences in sliding-mediated fluid recovery or kinetic friction behaviors between naïve and OA-like cartilage. However, OA-like cartilage experienced greater strain accumulation during load application, suggesting that elevated tissue strains (not friction-driven wear) may be the primary biomechanical mediator of OA pathology.