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Bacterial cellulose nanofiber (BCNF) with high thermal stability produced by an ecofriendly process has emerged as a promising solution to realize safe and sustainable materials in the large-scale battery. However, an understanding of the actual thermal behavior of the BCNF in the full-cell battery has been lacking, and the yield is still limited for commercialization. Here, we report the entire process of BCNF production and battery manufacture. We systematically constructed a strain with the highest yield (31.5%) by increasing metabolic flux and improved safety by introducing a Lewis base to overcome thermochemical degradation in the battery. This report will open ways of exploiting the BCNF as a "single-layer" separator, a good alternative to the existing chemical-derived one, and thus can greatly contribute to solving the environmental and safety issues.
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BACKGROUND: Dry eye disease is an aging-related ophthalmic disease that not only affects the daily activities but also causes deterioration in the quality of life. This study aimed to evaluate the factors associated with dry eye symptoms in elderly Koreans. METHODS: We investigated 4,185 subjects (men=1,787 and women=2,398) aged ≥65 years from the fifth Korea National Health and Nutrition Examination Survey 2010-2012. Data were analyzed using multiple logistic regressions to identify the relationships between dry eye symptoms and other factors. RESULTS: The prevalence of dry eye symptoms was 17.9%. After adjustment for confounding factors, dry eye symptoms were significantly associated with female sex (adjusted odds ratio [aOR], 1.806; 95% confidence interval [CI], 1.410-2.313), a history of cataract (aOR, 1.683; 95% CI, 1.255-2.255), suicidal ideation (aOR, 1.414; 95% CI, 1.070-1.870), hypercholesterolemia (aOR, 1.289; 95% CI, 1.025-1.621), age ≥80 years (aOR, 0.538; 95% CI, 0.337-0.859), and sleep duration ≥9 h/d (aOR, 0.524; 95% CI, 0.330-0.834). CONCLUSION: Among elderly Koreans, female sex, a history of cataract, suicidal ideation, and hypercholesterolemia may be the risk factors for dry eye symptoms, whereas sleep duration ≥9 h/d can be a protective factor against dry eye symptoms.
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BACKGROUND: The association between sleep duration and body composition measures in Korean adults remains unclear. METHODS: This cross-sectional study included 3,532 subjects aged ≥40 years (1,542 men and 1,990 women) who participated in the 2010 Korea National Health and Nutrition Examination Survey V-1. Self-reported sleep duration and anthropometric data were collected. Appendicular skeletal muscle mass (ASM) was quantified via dual-energy X-ray absorptiometry. Obesity was defined according to the body mass index and waist circumference. Sarcopenia was defined as the muscle mass percentage (ASM/weight) below the lowest quintile computed for the study population. Multivariate logistic regressions with or without adjustment for sociodemographic and lifestyle factors were used to evaluate the association of sleep duration with obesity and sarcopenia for participants who slept ≤5, 6-8, and ≥9 h/d. The results were expressed as odds ratios (ORs) with 95% confidence intervals (95% CIs). RESULTS: In women, the association between sleep duration and sarcopenia was stronger for individuals who slept ≥9 h/d than for those who slept 6-8 h/d (unadjusted OR, 1.99; 95% CI, 1.19-3.34; adjusted OR, 1.77; 95% CI, 1.06- 2.96). CONCLUSION: Longer sleep duration is associated with a significantly higher incidence of sarcopenia in Korean women aged ≥40 years.
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The electrochemical cycling performance of vanadium oxide nanotubes (VOx-NTs) for Mg-ion insertion/extraction was investigated in acetonitrile (AN) and tetramethylsilane (TMS)-ethyl acetate (EA) electrolytes with Mg(ClO4)2 salt. When cycled in TMS-EA solution, the VOx-NT exhibited a higher capacity retention than when cycled in AN solution. The significant degradation of capacity in AN solution resulted from increased charge-transfer resistance caused by the reaction products of the electrolyte during cycling. Mixed TMS-EA solvent systems can increase the cell performance and stability of Mg-electrolytes owing to the higher stability of TMS toward oxidation and the strong Mg-coordination ability of EA. These results indicate that the interfacial stability of the electrolyte during the charging process plays a crucial role in determining the capacity retention of VOx-NT for Mg insertion/extraction.
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In this study, we demonstrated the intercalation of Na in hydrothermally synthesized VOx nanotubes (NTs) and Ni-doped VOx NTs. The changes induced in the structures of the two nanomaterials during the Na intercalation process were investigated through X-ray diffraction (XRD) analyses. It was observed that the initial capacity and rate performance of the Ni-doped VOx NTs were improved. The results of X-ray photoelectron spectroscopy (XPS) and conductance measurement confirmed that higher initial capacity and rate performance were attributed to an increase in the valence states of vanadium and increased conductivity after the Ni exchange process.
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We report a new discovery for enhancing the energy density of manganese oxide (Nax MnO2 ) cathode materials for sodium rechargeable batteries by incorporation of aluminum. The Al incorporation results in NaAl(0.1) Mn(0.9) O2 with a mixture of tunnel and layered crystal structures. NaAl(0.1) Mn(0.9) O2 shows a much higher initial discharge capacity and superior cycling performance compared to pristine Na(0.65) MnO2 . We ascribe this enhancement in performance to the formation of a new orthorhombic layered NaMnO2 phase merged with a small amount of tunnel Na(0.44) MnO2 phase in NaAl(0.1) Mn(0.9) O2 , and to improvements in the surface stability of the NaAl(0.1) Mn(0.9) O2 particles caused by the formation of Al-O bonds on their surfaces. Our findings regarding the phase transformation and structure stabilization induced by incorporation of aluminum, closely related to the structural analogy between orthorhombic Na(0.44) MnO2 and NaAl(0.1) Mn(0.9) O2 , suggest a strategy for achieving sodium rechargeable batteries with high energy density and stability.
