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The speed of sound in helium was measured along five isotherms in a temperature range from 273 to 373 K at pressures from 15 to 100 MPa with a relative expanded uncertainty ( = 2) from 0.02 to 0.04%. A dual-path pulse-echo system was utilized to conduct these measurements. The data were compared with the reference equation of state developed by Ortiz Vega et al. At pressures up to 50 MPa, relative deviations were within the uncertainty of our measurements, while, at higher pressures, increasing negative deviations were observed up to -0.26%. We also compared the results with predictions based on the virial equation of state correct to the seventh virial coefficient, using the virial coefficients reported recently by Gokul et al., finding agreement to within the experimental uncertainty at all investigated states.
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http://dx.doi.org/10.1021/acs.jced.3c00083 | DOI Listing |
J Acoust Soc Am
September 2025
School of Ocean Engineering and Technology, Sun Yat-sen University, Zhuhai 519000, China.
This study establishes a quantitative framework using field observations and normal mode theory to reveal wind field control mechanisms over ambient noise vertical directionality in shallow water. Acoustic data from a vertical line array in the northern South China Sea, combined with sound speed profiles, seabed properties, and multi-source wind fields (ERA5 reanalysis/Weibull-distributed synthetics), demonstrate: (1) A 20-km spatial noise-energy threshold (>90% energy contribution), challenging conventional near-field assumptions (1-2 km); (2) frequency-dependent distribution: low-frequency (50-200 Hz) directionality depends on near-field sources, while high-frequency (>400 Hz) energy shifts seaward due to modal cutoff variations; (3) model validation shows 0.96 correlation at 100 Hz/100 km (stratified medium accuracy), but seabed interface waves induce 3.
View Article and Find Full Text PDFJ Proteome Res
September 2025
School of Life Sciences, Technical University of Munich, Emil Erlenmeyer Forum 5, Freising 85354, Germany.
Current applications of mass-spectrometry-based proteomics range from single-cell to body fluid analysis, each presenting very different demands regarding sensitivity or sample throughput. Additionally, the vast molecular complexity of proteomes and the massive dynamic range of protein concentrations in these biological systems require highly performant chromatographic separations in tandem with the high speed and sensitivity afforded by modern mass spectrometers. In this study, we focused on the chromatographic aspect and, more specifically, systematically evaluated proteome analysis performance across a wide range of chromatographic flow rates (0.
View Article and Find Full Text PDFJ Acoust Soc Am
September 2025
Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15213, USA.
Surficial sediments are highly susceptible to physical, biological, and chemical processes, which can create significant heterogeneity, affecting the transmission and scattering of elastic waves. Non-invasive medical shear wave elastography (SWE) can potentially resolve shear speed heterogeneity in this delicate surficial layer. Samples were extracted from two mudflats in New Hampshire, USA, where sound speed and attenuation were measured 1 cm below the water-sediment interface using the core and resonance logger (200 kHz-1 MHz).
View Article and Find Full Text PDFBiol Lett
September 2025
State Key Laboratory of Digital Medical Engineering Sanya Research Institute of Hainan University, Hainan University, Haikou, Hainan, China.
Neuroplasticity enables the brain to adapt neural activity, but whether this can be harnessed for abstract optimization tasks like seeking curve extrema remains unclear. Here, we used a brain-machine interface in mice, pairing auditory feedback of neuronal firing rate with water rewards, to investigate whether motor cortex neurons can optimize activity along a unimodal curve ([Formula: see text]). The curve maps firing rate ([Formula: see text]) to sound frequency increase speed ([Formula: see text]), where the curve extremum accelerates reward acquisition.
View Article and Find Full Text PDFNat Commun
September 2025
Department of Chemical Engineering, Hanyang University, Seoul, Republic of Korea.
Sensorineural hearing loss is the most common form of deafness, typically resulting from the loss of sensory cells on the basilar membrane, which cannot regenerate and thus lose sensitivity to sound vibrations. Here, we report a reconfigurable piezo-ionotropic polymer membrane engineered for biomimetic sustainable multi-resonance acoustic sensing, offering exceptional sensitivity (530 kPa) and broadband frequency discrimination (20 Hz to 3300 Hz) while remaining resistant to "dying". The acoustic sensing capability is driven by an ion hitching-in cage effect intrinsic to the ion gel combined with fluorinated polyurethane.
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