ObjectivesTo access the epidemiological characteristics of elderly people using emergency medical services (EMS) in Beijing, as a consequence of injurious falls, and the association between an ageing population and injurious falls.DesignA longitudinal observational study based on Beijing EMS data.SettingAll citizens aged 60 years or above who used EMS from 2010 to 2017 in Beijing, China.ParticipantsDuring 2010 to 2017, 2516 128 people used EMS in Beijing. Of these, 1528 938 people aged under 60 years were excluded and the remaining 987 190 people were included in our study.MethodsData were from the emergency dispatch database of Beijing’s Emergency Medical Centre. We described the proportion of elderly people using EMS in Beijing due to injurious falls with regard to region, time, sex, age and proportion of the elderly population.ResultsAmong the 987 190 participants who used EMS, 82 694 (8.38%) had had a fall. The proportion of falls rose from 7.12% in 2010 to 9.45% in 2017, and was higher in urban (8.62%) than in suburban (7.80%) regions. Elderly people were more likely to use EMS due to injurious falls during September to November (8.99%) than during December to February (7.68%) (adjusted OR (aOR)=1.19), and during 08:00 to 09:59 (10.02%) than during 00:00 to 01:59 (4.11%) (aOR=2.52). Elderly people in districts with high (8.92%, aOR=1.15) and medium (8.23%, aOR=1.09) proportions of an elderly population were more likely to use EMS due to injurious falls than those in districts with a low proportion of elderly population (7.81%).ConclusionsIn Beijing, the proportion of elderly people using EMS due to injurious falls increased with age, and was positively correlated with the proportion of the elderly population. Taking care of elderly people and preventing injurious falls should be one of the key issues to be handled in a society with an ageing population.
The passivation caused by the deposition of the insulating
discharge
final product, lithium sulfide (Li2S), leads to the instability
of the cycle and the rapid capacity fading of lithium–sulfur
batteries (LSBs), which restricts the development of LSBs. This paper
proposes the employment of trifluoroacetamide (TFA) as an electrolyte
additive to alleviate the passivation by increasing the solubility
of Li2S. The solubilization effect of TFA on Li2S is attributed to intermolecular hydrogen bonds and O–Li
bonds. Li2S in the TFA-based electrolyte exhibits a flower-like
3D deposition behavior, which further alleviates the surface passivation
of the electrode and impels conversion kinetics. In addition, the
LiF-rich solid electrolyte interface layer can effectively defend
the Li metal anode and suppress the growth of Li dendrites. Accordingly,
the discharge capacity of the TFA-based battery remains at an excellent
681.2 mA h g–1 after 400 cycles with a Coulombic
efficiency of 99% at 0.5 C. After the battery stabilizes, the capacity
decay is only 0.036% per cycle. Under harsh conditions, such as high
rates (2 C) and high sulfur loadings (5.2 mg cm–2) with lean electrolytes and elevated temperatures (60 °C),
TFA-containing batteries exhibited more durable and stable cycling.
This paper provides new insights into solving practical problems and
gives an impetus in cycle stability for LSBs.
Due to the drastic aerodynamic heating effect in supersonic aircrafts, the operational performance of wave-transmitting dielectric ceramics functionalized radomes strongly depends on the temperature and oxidation. In this paper, the evolution of microwave dielectric responses in Si3N4 ceramics via gelcasting over a wide temperature range (25°C∼800°C) is investigated experimentally and theoretically. Specifically, the relative increment rate of real permittivity over evaluated temperature range is 4.46% at 8.2GHz and 8.67% at 12.4GHz, while the imaginary permittivity remains less than 0.06. Taking temperature-dependent polarized bound charge and damping coefficient into consideration, a revised dielectric relaxation model with Lorentz correction for Si3N4 ceramics has been established, which agrees well with evolution of experimental results. Furthermore, the best fitting results indicate that the activation energy of electrons Ea (15.46 ∼17.49 KJ/mol) is less than that of lattice Eb (33.29∼40.40 KJ/mol), which could be ascribed to the binding force between the electrons and nucleus is lower than covalent bonding force of lattice. Besides, excellent restorable feature of permittivity after heat-treatment lays a solid foundation for radome materials serviced in high temperature circumstances.
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