Histological and impedance changes of skeletal muscle by whole-body critical irradiation in a rat model.

In this study, the electrical resistance of the whole body and histological changes of skeletal muscle were investigated in rats according to the increase in radiation dose. A total of 15 male Sprague-Dawley rats (5-weeks-old) were randomly divided into 5 groups (each, n = 3). Each group received 1 Gy, 5 Gy, 10 Gy and 20 Gy systemic exposure, and the non-irradiated group was used as a control for morphological comparison. After attaching an electrode clip to the forelimb of the rat, an AC frequency was applied before and 4 days after irradiation using an impedance/gain-phase analyzer, and the measurement system was automatically controlled with LabVIEW. Comparing to before irradiation after 4 days, the difference in the average impedance values at 1 Gy, 5 Gy, 10 Gy, and 20 Gy was 1188±989 ohm, 3076±2251 ohm, 7650±6836 ohm, and 10478±6250 ohm, respectively. By comparing the normal group and the experimental group, muscle fiber atrophy and collagen fibers around blood vessels were observed (p < 0.05, control group vs 5 Gy or more high-dose group). These results confirmed the previously reported morphological changes of skeletal muscle and our hypothesis that whole-body impedance measurement enables to reflect tissue changes after irradiation.

Changes of electrical impedance characteristics with the radiation induced damage on biological tissue constituents.

This study analyzes the response of increasing radiation dose to the pork tenderloin tissue. Considering its significant cell structure, pork tenderloin tissue samples are selected for the experimental objects to measure their electrical impedance characteristics. This study proposes and investigates an effective approach to characterize the variation of the internal change of the components of pork tenderloin tissues caused by radiation. Changes in the pork tenderloin tissues are that the gap of the myotome is more far apart with increase of radiation dose because of the destroyed Myofibrils under the damage. With the increase of radiation dose, the impedance value of the pork tenderloin tissue decreases. Each of mean differences in the impedance values before and after irradiation dose under 1 Gy, 2 Gy and 4 Gy show 0.55±0.03, 1.09±0.14 and 1.97±0.14, respectively. However, the mean difference substantially increases to 13.08±0.16 at irradiation dose of 10 Gy. Thus, the cell membrane shows the most severe rupture at a radiation dose of 10 Gy. Changes in the microstructure of the irradiated pork tenderloin tissue samples are also checked and validated by a transmission electron microscope.

Hydrophilicity/porous structure-tuned, SiO2/polyetherimide-coated polyimide nonwoven porous substrates for reinforced composite proton exchange membranes.

Porous substrate-reinforced composite proton exchange membranes have drawn considerable attention due to their promising application to polymer electrolyte membrane fuel cells (PEMFCs). In the present study, we develop silica (SiO(2)) nanoparticles/polyetherimide (PEI) binders-coated polyimide (PI) nonwoven porous substrates (referred to as "S-PI substrates") for reinforced composite membranes. The properties of S-PI substrates, which crucially affect the performance of resulting reinforced composite membranes, are significantly improved by controlling the hygroscopic SiO(2) particle size. The 40 nm S-PI substrate (herein, 40 nm SiO(2) particles are employed) shows the stronger hydrophilicity and highly porous structure than the 530 nm S-PI substrate due to the larger specific surface area of 40 nm SiO(2) particles. Based on the comprehensive understanding of the S-PI substrates, the structures and performances of the S-PI substrates-reinforced composite membranes are elucidated. In comparison with the 530 nm S-PI substrate, the hydrophilicity/porous structure-tuned 40 nm S-PI substrate enables the impregnation of a large amount of a perfluorosulfonic acid ionomer (Nafion), which thus contributes to the improved proton conductivity of the reinforced Nafion composite membrane. Meanwhile, the reinforced Nafion composite membranes effectively mitigate the steep decline of proton conductivity with time at low humidity conditions, as compared to the pristine Nafion membrane. This intriguing finding is further discussed by considering the unusual features of the S-PI substrates and the state of water in the reinforced Nafion composite membranes.