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1. A Chemical Pump that Generates High‐Pressure Gas by Transmitting Liquid Fuel against Pressure Gradient

   https://doi.org/10.1002/aisy.202100246  

   Kim, Junsoo ; Luo, Kai ; Suo, Zhigang ( May 2022 , Advanced Intelligent Systems)

   A pneumatic soft robot can be made autonomous by carrying a liquid chemical fuel. In the existing design, to transmit the fuel, the pressure of the fuel tank must exceed that of the actuator. Consequently, the fuel tank must be sufficiently stiff, which hardens the robot. Herein, inspired by pit membranes in trees, a chemical pump is developed, which is consisting of a nanoporous membrane between the fuel tank and the actuator, and coated with a catalyst on the side of the actuator. The fuel in the fuel tank migrates across the membrane and, on meeting the catalyst, decomposes into a pressurized gas and inflates the actuator. The chemical pump is driven by the free energy of reaction, against the difference in pressure. The pores in the membrane are large enough for the fuel molecules to migrate through, but small enough to block the pressurized gas to tunnel back. In a demonstration, the fuel tank has ambient pressure, and the actuator has a pressure of 350 kPa, comparable to the pressure in a car tire. The chemical pump enables pneumatic robots to be autonomous, powerful, and soft.

    

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2. Agreement of rebound and applanation tonometry intraocular pressure measurements during atmospheric pressure change

   https://doi.org/10.1371/journal.pone.0259143  

   Vercellin, Alice Verticchio ; Harris, Alon ; Siesky, Brent ; Zukerman, Ryan ; Tanga, Lucia ; Carnevale, Carmela ; Scarinci, Fabio ; Oddone, Francesco ( October 2021 , PLOS ONE)

   Grzybowski, Andrzej (Ed.)

   This study investigated the agreement of intraocular pressure measurements using rebound tonometry and applanation tonometry in response to atmospheric changes in a hyperbaric chamber. Twelve eyes of 12 healthy subjects were included in this prospective, comparative, single-masked study. Intraocular pressure measurements were performed by rebound tonometry followed by applanation tonometry in a multiplace hyperbaric chamber at 1 Bar, followed by 2, 3 and 4 Bar during compression and again at 3 and 2 Bar during decompression. Mean differences between rebound and applanation intraocular pressure measurements were 1.6, 1.7, and 2.1 mmHg at 2, 3, and 4 Bar respectively during compression and 2.6 and 2.2 mmHg at 3 and 2 Bar during decompression. Lower limits of agreement ranged from -3.7 to -5.9 mmHg and upper limits ranged from -0.3 to 1.9 mmHg. Multivariate analysis showed that the differences between rebound and applanation intraocular pressure measurements were independent of atmospheric pressure changes (p = 0.79). Intraocular pressure measured by rebound tonometry shows a systematic difference compared to intraocular measured by applanation tonometry, but this difference is not influenced by changes of atmospheric pressure up to 4 Bar in a hyperbaric chamber. Agreement in magnitude of change between devices suggests rebound tonometry is viable for assessing intraocular pressure during atmospheric changes. Future studies should be designed in consideration of expected differences in IOP values provided by the two devices. 

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3. Under pressure: design and validation of a pressure-sensitive insole for ankle plantar flexion biofeedback during neuromuscular gait training

   https://doi.org/10.1186/s12984-022-01119-y  

   Conner, Benjamin C. ; Fang, Ying ; Lerner, Zachary F. ( December 2022 , Journal of NeuroEngineering and Rehabilitation)

   Electromyography (EMG)-based audiovisual biofeedback systems, developed and tested in research settings to train neuromuscular control in patient populations such as cerebral palsy (CP), have inherent implementation obstacles that may limit their translation to clinical practice. The purpose of this study was to design and validate an alternative, plantar pressure-based biofeedback system for improving ankle plantar flexor recruitment during walking in individuals with CP.

   Eight individuals with CP (11–18 years old) were recruited to test both an EMG-based and a plantar pressure-based biofeedback system while walking. Ankle plantar flexor muscle recruitment, co-contraction at the ankle, and lower limb kinematics were compared between the two systems and relative to baseline walking.

   Relative to baseline walking, both biofeedback systems yielded significant increases in mean soleus (43–58%, p < 0.05), and mean (68–70%, p < 0.05) and peak (71–82%, p < 0.05) medial gastrocnemius activation, with no differences between the two systems and strong relationships for all primary outcome variables (R = 0.89–0.94). Ankle co-contraction significantly increased relative to baseline only with the EMG-based system (52%, p = 0.03).

   These findings support future research on functional training with this simple, low-cost biofeedback modality.

    

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4. High pressure raman spectroscopy and X-ray diffraction of K2Ca(CO3)2 bütschliite: multiple pressure-induced phase transitions in a double carbonate

   https://doi.org/10.1007/s00269-023-01262-5  

   Zeff, G. ; Kalkan, B. ; Armstrong, K. ; Kunz, M. ; Williams, Q. ( January 2024 , Physics and Chemistry of Minerals)

   The crystal structure and bonding environment of K₂Ca(CO₃)₂bütschliite were probed under isothermal compression via Raman spectroscopy to 95 GPa and single crystal and powder X-ray diffraction to 12 and 68 GPa, respectively. A second order Birch-Murnaghan equation of state fit to the X-ray data yields a bulk modulus,$${K}_{0}=46.9$$$K_0=46.9$GPa with an imposed value of$${K}_{0}^{\prime}= 4$$$K_0^{\prime }=4$for the ambient pressure phase. Compression of bütschliite is highly anisotropic, with contraction along thec-axis accounting for most of the volume change. Bütschliite undergoes a phase transition to a monoclinicC2/mstructure at around 6 GPa, mirroring polymorphism within isostructural borates. A fit to the compression data of the monoclinic phase yields$${V}_{0}=322.2$$$V_0=322.2$ Å³$$,$$$,$$${K}_{0}=24.8$$$K_0=24.8$GPa and$${K}_{0}^{\prime}=4.0$$$K_0^{\prime }=4.0$using a third order fit; the ability to access different compression mechanisms gives rise to a more compressible material than the low-pressure phase. In particular, compression of theC2/mphase involves interlayer displacement and twisting of the [CO₃] units, and an increase in coordination number of the K⁺ion. Three more phase transitions, at ~ 28, 34, and 37 GPa occur based on the Raman spectra and powder diffraction data: these give rise to new [CO₃] bonding environments within the structure.

    

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5. A Device for Reducing Pressure Ulcers in Bedridden Patients Using Fiber Reinforced Elastomeric Enclosures (FREEs)

   https://doi.org/10.1115/IMECE2022-95255  

   Russo, Lea ; Gondhalekar, Mihir ; Kota, Sridhar ; Bassin, Benjamin ( October 2022 , Proceedings of the ASME 2022 International Mechanical Engineering Congress and Exposition. Volume 4: Biomedical and Biotechnology; Design, Systems, and Complexity.)

   This paper describes the design, development, and prototype testing of a device that can relieve contact pressure to potentially prevent pressure ulcers in bedridden patients by utilizing pneumatically actuated Fiber-Reinforced Elastomeric Enclosures (FREEs) [1,2].

   Bedsores, or pressure ulcers, develop in bedridden patients due to constant contact pressure between a patient’s skin and an external (bed) surface. It is estimated that over 2.5 million patients [8] suffer from pressure ulcer developments annually in the United States. High pressure areas of the body include the sacrum and heel, with 36% of pressure ulcers occurring at the sacrum and 30% occurring at the heel. All other body areas each account for only 6% of pressure ulcer occurrence [6]. They are a major concern for low-mobility, patients who are bedridden for an extended periods and are associated with a 5x increase in patient mortality [3]. In addition, pressure ulcers place a significant cost burden on patients. Development of Stage 4 pressure ulcers and associated comorbidities can cost on average $127,000 to the patient [4]. This high cost is mainly due to attending caregiver’s time.

   The most common solution for preventing the development of pressure ulcers in bed ridden hospital patients is for the attending nurses to reposition the patients every 2 hours so that the affected areas are relieved of any contact pressure. Repositioning patients is time consuming and strenuous for health care providers. General purpose “dynamic” pressure relief mattresses have shown to be somewhat effective in reducing the development of pressure ulcers. However, they do not effectively target high pressure areas and still necessitate frequent repositioning.

   FREEs can be designed to generate a variety of shapes and motions once actuated (pressurized) and serve as building blocks for soft robotic applications. When FREEs, arranged in parallel, are embedded in a material with compatible elastic properties they propagate their deformed shape throughout the surface. These compliant sheets of FREEs are capable of sustaining loads while relieving pressure on high pressure areas of the body. The prototype for the device presented in this paper was designed for relieving pressure on a patient’s heel area. Preliminary test results demonstrate that the prototype device is effective at lifting a patient’s ankle, for patients weighing up to 250lbs, thus relieving contact pressure. The research also demonstrates the viability of developing modular pressure-relieving pads embedded with more advanced FREEs than described in this paper that can be tailored to relieve contact pressure on other affected areas such as the sacrum.

    

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