RESUMEN
Herein we report crystal growth control of rod-shaped ε-Fe2O3 nanocrystals by developing a synthesis based on the sol-gel technique using ß-FeO(OH) as a seed in the presence of a barium cation. ε-Fe2O3 nanocrystals are obtained over a wide calcination temperature range between 800 °C and 1000 °C. A low calcination temperature (800 °C) provides an almost cubic rectangular-shaped ε-Fe2O3 nanocrystal with an aspect ratio of 1.4, whereas a high calcination temperature (1000 °C) provides an elongated rod-shaped ε-Fe2O3 nanocrystal with an aspect ratio of 3.3. Such systematic anisotropic growth of ε-Fe2O3 is achieved due to the wide calcination temperature in the presence of barium cations. The surface energy and the anisotropic adsorption of barium on the surface of ε-Fe2O3 can explain the anisotropic crystal growth of rod-shaped ε-Fe2O3 along the crystallographic a-axis. The present work may provide important knowledge about how to control the anisotropic crystal shape of nanomaterials.
RESUMEN
OBJECTIVES/HYPOTHESIS: Epidemiological information regarding the relationship between household income and education and hearing impairment (HI) is limited. The present cross-sectional study investigated this issue in Japan. STUDY DESIGN: Cross-sectional investigation. METHODS: Study subjects were 371 men and 639 women aged 36 to 84 years. A self-administered questionnaire was used. Audiological assessment was performed by pure-tone audiometry. HI was defined as present in subjects who did not respond to a pure-tone average of >25 dB HL in the better hearing ear according to the World Health Organization standard. Adjustment was made for age, smoking status, alcohol consumption, hypertension, dyslipidemia, diabetes mellitus, and body mass index. RESULTS: The prevalence of HI was 31.5% in 371 men and 20.8% in 639 women. In men, a slight inverted J-shaped association was observed between household income and HI, compared with a household income of <3 million yen per year. A household income of 3 to 5 million yen, but not of 5 million yen or more, was independently inversely associated with the prevalence of HI; the prevalence ratio for 3 to 5million yen was 0.73 (95% confidence interval: 0.54-0.999). After adjustment for confounding factors, no relationship was found between household income and the prevalence of HI in women. There were no associations between educational level and the prevalence of HI in either men or women in the multivariate model. CONCLUSIONS: Our results suggest that medium, but not high, household income may be associated with a lower prevalence of HI only in men. LEVEL OF EVIDENCE: 2b Laryngoscope, 129:2153-2157, 2019.
