The failure mechanism of LiFePO 4 cells during overcharge conditions has been systematically studied using commercial A123 18650 cells at a 1C rate and different conditions -from 5% to 20% overcharge (SOC = 105% to 120%). SEM/EDX, high-energy synchrotron XRD (HESXRD), and cyclic voltammetry (CV) were used to characterize the morphology, structure, and electrode potentials of cell components both in situ and ex situ. The failure behaviors for A123 18650 cells experiencing different degrees of overcharges were found to be similar, and the 10% overcharge process was analyzed as the representative example. The Fe redox potentials in the 1.2 M LiPF 6 EC/EMC electrolyte were measured during the overcharge/discharge process using CV, proving that Fe oxidation and reduction in the cell during the overcharge/discharge cycle is theoretically possible. A possible failure mechanism is proposed: during the overcharging process, metallic Fe oxidized first to Fe 2+ , then to Fe 3+ cations; next, these Fe 2+ and Fe 3+ cations diffused to the anode side from the cathode side; and finally, these Fe 3+ cations reduced first to Fe 2+ cations, and then reduced further, back to metallic Fe. During overcharge/discharge cycling, Fe dendrites continued growing from both the anode and the cathode sides simultaneously, penetrating through the separator and forming an iron bridge between the anode and cathode. The iron bridge caused micro-shorting and eventually led to the failure of the cell. During the overcharge/discharge cycles, the continued cell temperature increase at the end of overcharge is evidence of the micro-shorting.

Background The Jamar hydraulic dynamometer is a widely recognized tool for measuring grip strength. Nevertheless, the devices used most often in Asian countries are spring-type dynamometers, represented by the CAMRY dynamometer or Smedley dynamometer. We aimed to evaluate the reliability and validity of the CAMRY dynamometer compared with the Jamar dynamometer. Methods This was a cross-sectional study using a random crossover design in the grip strength test with two dynamometers. A total of 1064 healthy community-dwelling older adults aged 50–90 years old, which included 686 minorities and 378 Han Chinese, were recruited into the study from July to September 2021. We assessed the reliability and validity of the CAMRY EH101 dynamometer, and the Jamar dynamometer was regarded as the reference device. The order of testing with two dynamometers was randomized in a 1:1 ratio, with a 10-min gap between the two devices. Intraclass correlation coefficients (ICCs) and Bland–Altman analysis were calculated to assess reliability and validity between the two devices. Results The average handgrip strength (HGS) values at six times by the Jamar and CAMRY devices were 25.0 ± 7.9 kg and 24.6 ± 7.5 kg, respectively. The ICC values between the two devices were 0.815–0.854, and the systematic bias underestimated by the CAMRY dynamometer was 0.5 kg in men and 0.6 kg in women. We carried out a linear regression equation by sex, and their relationship was found as follows: male HGS (kg)Jamar = 8.001 + 0.765 × HGS (kg)CAMRY; female HGS (kg)Jamar = 3.681 + 0.840 × HGS (kg)CAMRY. Conclusions The CAMRY EH101 dynamometer provides excellent reliability and validity. This device can serve as a reliable, inexpensive, and practical device to assess grip strength in geriatric clinical practice. Clinical trial registration Chinese Clinical Trial Registry: ChiCTR2100046367; Date of clinical trial reistration: 15/05/2021.

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Peroxisome proliferator-activated receptor- (PPAR-) γ is a ligand-dependent transcription factor, and it has become evident that PPAR-γ agonists have renoprotective effects, but their influence and mechanism during the development of calcium oxalate (CaOx) nephrolithiasis remain unknown. Rosiglitazone (RSG) was used as a representative PPAR-γ agonist in our experiments. The expression of transforming growth factor-β1 (TGF-β1), hepatocyte growth factor (HGF), c-Met, p-Met, PPAR-γ, p-PPAR-γ (Ser112), Smad2, Smad3, pSmad2/3, and Smad7 was examined in oxalate-treated Madin-Darby canine kidney (MDCK) cells and a stone-forming rat model. A CCK-8 assay was used to evaluate the effects of RSG on cell viability. In addition, intracellular reactive oxygen species (ROS) levels were monitored, and lipid peroxidation in renal tissue was detected according to superoxide dismutase and malondialdehyde levels. Moreover, the location and extent of CaOx crystal deposition were evaluated by Pizzolato staining. Our results showed that, both in vitro and in vivo, oxalate impaired PPAR-γ expression and phosphorylation, and then accumulative ROS production was observed, accompanied by enhanced TGF-β1 and reduced HGF. These phenomena could be reversed by the addition of RSG. RSG also promoted cell viability and proliferation and decreased oxidative stress damage and CaOx crystal deposition. However, these protective effects of RSG were abrogated by the PPAR-γ-specific inhibitor GW9662. Our results revealed that the reduction of PPAR-γ activity played a critical role in oxalate-induced ROS damage and CaOx stone formation. RSG can regulate TGF-β1 and HGF/c-Met through PPAR-γ to exert antioxidant effects against hyperoxaluria and alleviate crystal deposition. Therefore, PPAR-γ agonists may be expected to be a novel therapy for nephrolithiasis, and this effect is related to PPAR-γ-dependent suppression of oxidative stress.

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The failure mechanism of commercial A123 18650 LiFePO 4 battery in the overcharge failure process at 1C and 110% SOC has been studied. It has been shown the battery failed quickly after 11 cycles with an increasing surface temperature. The battery surface temperature and capacity were monitored and analyzed during overcharge testing. A special home-designed three-electrode A123 18650 LiFePO 4 cell with Li metal as reference electrode was made to monitor the voltage of anode, cathode and full cell respectively in the 10% overcharge process. It was found that, during the normal cycle, the anode and cathode voltages were from -0.25 V to 0.25 V and 2.60 V to 4.50 V respectively, while in the 10% overcharge process, the anode voltage was between -0.4V to 0.22V (vs. Li/Li + ) and the cathode voltage changed from 2.20 V to 4.86 V (vs. Li/Li + ). The overcharge failure was studied using SEM and EDX. It was found that coding spots appeared in the anode side. Fe, Ni and Ge were found only in the coding spots by performing EDX, indicating the micro shorting by metal dendrite is the main reason of the failure of battery during the 10% overcharge process. It could be concluded from the results of High Energy Synchrotron X-ray Diffraction (HESXRD) that Fe was not from the decomposition of LiFePO 4 . A half cell cyclic voltammograms experiment was also carried out for further understanding of the behavior of iron corrosion. The potential of Fe/Fe 2+ oxidation/reduction pair in the LiPF6/EC-EMC electrolyte system was found to be 2.2 V/2.7 V. It was concluded that Fe cations could not only be reduced on the surface of graphite, but also at the cathode side during the overcharge process. Compared with normal cycle, under the overcharge process, the impurities containing iron in the raw material was more conducted to dendrite formation leading to micro-shorting because of the wider reduction voltage range in the overcharge process.

Compared with the electrosurgery device, the ultrasonic device could be superior with more clinical effectiveness. The trial sequential analysis demonstrated that further studies about the operative time were not needed.

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