Mechanical properties of the cardiac tissue play an important role in normal heart function. The goal of this study was to determine the passive mechanical properties of all heart chambers through a paired comparison study in an ovine model. Ovine heart was used due its physiological and anatomical similarities to human heart. A total of 189 specimens from anterior and posterior portions of the left and right ventricles, atria, and appendages underwent biaxial mechanical testing. A Fung-type strain energy function was used to fit the experimental data. Tissue behavior was quantified based on the magnitude of strain energy, as indicator of tissue stiffness, at equibiaxial strains of 0.10, 0.15, and 0.20. Statistical analysis revealed no significant difference in strain energy storage between anterior and posterior portions of each chamber, except for the right ventricle where strain energy storage in the posterior specimens were higher than the anterior specimens. Additionally, all chambers from the left side of the heart had significantly higher strain energy storage than the corresponding chambers on the right side. Furthermore, the highest to lowest stored strain energy were associated with ventricles, appendages, and atria, respectively. Microstructure of tissue specimens from different chambers was also compared using histology.
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Sci Rep
December 2024
College of Civil Engineering, Inner Mongolia University of Science and Technology, Baotou, 014010, Inner Mongolia, China.
The mechanical responses of sandy soil under dynamic loading is closely related to protective engineering and geotechnical engineering, is still not fully understood. To investigate the energy attenuation law and propagation velocity of compressed waves in dry sandy soil, this paper focuses on the dynamic response of compression waves in the specimen under single impact and repetitive impact conditions using an improved split Hopkinson pressure bar (SHPB). The results reveal that the length of the specimen follows an exponential relationship with the attenuation of the peak stress.
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December 2024
Department of Mechanical and Aerospace Engineering, University of California, Irvine, Irvine, CA, USA.
Tightly bound electron-hole pairs (excitons) hosted in atomically-thin semiconductors have emerged as prospective elements in optoelectronic devices for ultrafast and secured information transfer. The controlled exciton transport in such excitonic devices requires manipulating potential energy gradient of charge-neutral excitons, while electrical gating or nanoscale straining have shown limited efficiency of exciton transport at room temperature. Here, we report strain gradient induced exciton transport in monolayer tungsten diselenide (WSe) across microns at room temperature via steady-state pump-probe measurement.
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December 2024
Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea.
The mechanisms underlying the impact of probiotic supplementation on health remain largely elusive. While previous studies primarily focus on the discovery of novel bioactive bacteria and alterations in the microbiome environment to explain potential probiotic effects, our research delves into the role of living Lactiplantibacillus (formerly known as Lactobacillus) and their conditioned media, highlighting that only the former, not dead bacteria, enhance the healthspan of Caenorhabditis elegans (C. elegans).
View Article and Find Full Text PDFInt J Biol Macromol
December 2024
College of Food Science and Biotechnology, Zhejiang Gongshang University, 149 Jiaogong Road, Hangzhou, Zhejiang Province 310035, People's Republic of China. Electronic address:
Glutamate decarboxylases (GADs) can catalyze the conversion of l-glutamate to γ-aminobutyric acid (GABA), while consuming one H. However, the GADs found so far are catalytically active in the pHs of 3.8-5.
View Article and Find Full Text PDFFront Microbiol
December 2024
Key Laboratory of Agro-Products Processing Technology of Shandong Province, Key Laboratory of Novel Food Resources Processing Ministry of Agriculture, Institute of Food & Nutrition Science and Technology, Shandong Academy of Agricultural Sciences, Jinan, China.
Alginate lyases can fully degrade alginate into various size-defined unsaturated oligosaccharide products by -elimination. Here, we identified the bifunctional endolytic alginate lyase Aly35 from the marine bacterium sp. Strain H204.
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