RESUMO
Ice air jet technology is one non-destructive, residue-free and environmentally friendly machining process. It is an efficient method to form ice particles by atomizing water droplets in ultra-low temperature environment. The freezing characteristics of water droplets in cryogenic gas and liquid nitrogen environment are visually analyzed, and the effects of droplet volume, ambient temperature are also studied. The results show that when water droplets freeze in a cryogenic gas environment, four distinct stages are observed, namely pre-cooling stage, recalescence stage, solidification stage, and deep cooling stage. However, when water droplets freeze in liquid nitrogen, the recalescence stage cannot be observed. For a 5 µl water droplet, it takes 68 s for water droplets to freeze into ice particles at - 20.36 °C, while it takes only 1.7 s in liquid nitrogen. During the freezing process, the water droplets form an ice shell outside and freeze inwardly. Ice particles may break up due to differences in solubility and density. With the increase of volume the time spent on pre-cooling stage and freezing stage both increases. For the large latent heat of water phase transformation, the solidification stage time is greatly affected by the volume of water droplets. When the ambient temperature drops from - 10.67 °C to - 24.68 °C, the freezing time of 5 µl water droplets decreases by 45.5%, indicating that the ambient temperature has a great influence on the freezing time. The results of the study can significantly contribute to the development of ice air jet technology.
RESUMO
BACKGROUND: The contribution of language preference and ethnicity to muscle strength and physical performance is unclear. We examined the associations of reading language preferences with muscle strength and performance in Chinese women and compared them to other ethnicities. METHODS: The Integrated Women's Health Programme (IWHP) cohort comprised community-dwelling, midlife Singaporean women aged 45-69. Ethnic Chinese women could choose between the English or Chinese versions of the questionnaire. Malay and Indian women were presented with the English version. Sociodemographic, reproductive, anthropometric characteristics were obtained. Hand grip strength and physical performance were objectively assessed. Visceral adiposity (VAT) was determined by Dual-energy X-ray Absorptiometry. Multivariable logistic regression models were used to determine independent associations of language preference/ethnicity with muscle strength and physical performance. RESULTS: The cohort comprised 1164 women (mean age: 56.3±6.2 years); 84.1% Chinese, 5.6% Malay, and 10.3% Indian. 315 Chinese participants (32.2%) had a Chinese-language reading preference (CLP). CLP women tended to be parous, of a lower socioeconomic status (lower proportions received tertiary education, lower employment rates and lower household income), and engaged in less physical activity compared to Chinese women with an English-language preference (ELP). This translated to a weaker hand grip strength (aOR: 1.56; 95%CI: 1.07-2.27), slower repeated chair stand (1.55; 1.12-2.13), poorer balance on tandem stand (2.00; 1.16-3.47), and a slower gait speed (1.62; 1.06-2.47). Compared to ELP women, Malay women had higher odds of poor hand grip strength (1.81; 1.12-2.93) while Indians had a higher odd of poor balance on one-leg stand (2.12; 1.28-3.52) and slow gait speeds on usual (1.88; 1.09-3.25) and narrow walks (1.91; 1.15-3.17). CONCLUSIONS: Chinese language reading preference was associated with inferior muscle strength and physical performance. Such disparities were largest and most consistent in the CLP group, followed by Indian and Malay women compared to the ELP group. Further studies should determine if CLP-associated muscle weakness can predict adverse health outcomes.