Mobile Application Use and Loneliness among Older Adults in the Digital Age: Insights from a Survey in Hong Kong during the COVID-19 Pandemic.

Existing literature on the associations between use of mobile applications (i.e., mobile apps) and loneliness among older adults (OAs) has been mainly conducted before the outbreak of the COVID-19 pandemic. Since mobile apps have been increasingly used by OAs during the pandemic, subsequent effects on social and emotional loneliness need updated investigation. This paper examines the relationship between mobile app use and loneliness among Hong Kong's OAs during the pandemic. In our research, 364 OAs with current use experience of mobile apps were interviewed through a questionnaire survey conducted during July and August 2021, which assessed the use frequency and duration of 14 mobile app types and levels of emotional and social loneliness. The survey illustrated communication (e.g., WhatsApp) and information apps were the most commonly used. Emotional loneliness was associated with the use of video entertainment (frequency and duration), instant communication (duration), and information apps (duration). Association between video entertainment apps' use and emotional loneliness was stronger among older and less educated OAs. Our findings highlight the distinctive relationships between different types of apps and loneliness among Hong Kong's OAs during the pandemic, which warrant further exploration via research into post-pandemic patterns and comparative studies in other regions.

Activation of boron nitride nanotubes and their polymer composites for improving mechanical performance.

Boron nitride nanotubes (BNNTs) are inappropriate for further chemical derivatization because of their chemical inertness. We demonstrate covalent activation of chemically inert BNNTs by isophorone diisocyanate (IPDI) to form isocyanate group (NCO)-terminated BNNT precursors with an 'NCO anchor' ready for further functionalization. As identified by Fourier transform infrared spectroscopy, a number of molecules or polymers with -COOH, -OH or -NH2 groups are readily attached to the activated IPDI-BNNTs. The IPDI-BNNT-involving polymer composites have shown mechanical properties are considerably improved due to the good dispersibility of IPDI-BNNTs in the polymer matrix and the strong interfacial interactions between BNNTs and polymers. The methodology reported here provides a promising method to promote the chemical reactivity of BNNTs and covalently modify polymer nanocomposites with improved mechanical performance.

Fabrication of multi-level carbon nanotube arrays with adjustable patterns.

Multi-level carbon nanotube (CNT) arrays with adjustable patterns were prepared by a combination of the breath figure (BF) process and chemical vapor deposition. Polystyrene-b-poly(acrylic acid)/ferrocene was dissolved in carbon disulfide and cast onto a Si substrate covered with a transmission electron microscope grid in saturated relative humidity. A two-level microporous hybrid film with a block copolymer skeleton formed on the substrate after evaporation of the organic solvent and water. One level of ordered surface features originates from the contour of the hard templates; while the other level originates from the condensation of water droplets (BF arrays). Ultraviolet irradiation effectively cross-linked the polymer matrix and endowed the hybrid film with improved thermal stability. In the subsequent pyrolysis, the incorporated ferrocene in the hybrid film was oxidized and turned the polymer skeleton into the ferrous inorganic micropatterns. Either the cross-linked hybrid film or the ferrous inorganic micropatterns could act as a template to grow the multi-level CNT patterns, e.g. isolated and honeycomb-structured CNT bundle arrays perpendicular to the substrate.