This study examined and verified the level of e-health literacy (e-HL) and infection preventive behaviors related to COVID-19 among undergraduate students majoring in healthcare. An online survey was conducted with 274 university students majoring in nursing, clinical pathology, and occupational therapy in South Korea. The e-HL consisted of functional, communicational, and critical literacy, and preventive behaviors were based on the Prevention Guideline on Droplet Infection. The mean score for e-HL was 3.62, with nursing students obtaining the highest scores. The overall e-HL score and the scores on its three sub-dimensions were related to infection-preventive behaviors. Moreover, e-HL affected infection-preventive behaviors (p < 0.001). Findings from this study highlight the necessity of education for improving the e-HL of undergraduate students majoring in healthcare to strengthen infection-preventive behaviors and protect patients from infectious diseases.

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Nickel-rich layered oxides (LiNi 1−x−y Co x Mn y O 2 ; (1 − x − y) ≥ 0.6), the high-energy-density cathode materials of lithium-ion batteries (LIBs), are seriously unstable at voltages higher than 4.5 V versus Li/Li + and temperatures higher than 50 °C. Herein, we demonstrated that the failure mechanism of a nickel-rich layered oxide (LiNi 0.6 Co 0.2 Mn 0.2 O 2 ) behind the instability was successfully suppressed by employing cyanoethyl poly(vinyl alcohol) having pyrrolidone moieties (Pyrd-PVA-CN) as a metal-ionchelating gel polymer electrolyte (GPE). The metal-ion-chelating GPE blocked the plating of transition-metal ions dissolved from the cathode by capturing the ions (anode protection). High-concentration metal-ion environments developed around the cathode surface by the GPE suppressed the irreversible phase transition of the cathode material from the layered structure to the rock-salt structure (cathode protection). Resultantly, the capacity retention was significantly improved at a high voltage and a high temperature. Capacity retention and coulombic efficiency of a full-cell configuration of a nickel-rich layered oxide with graphite were significantly improved in the presence of the GPE especially at a high cutoff voltage (4.4 V) and an elevated temperature (55 °C).

Lead halide perovskites nanocrystals have emerged as a leading candidate in perovskite solar cells and light-emitting diodes. Given their favorable, tunable optoelectronic properties through modifying the size of nanocrystals, it is imperative to understand and control the growth of lead halide perovskite nanocrystals. However, during the nanocrystal growth into bulk films, the effect of halide bonding on growth kinetics remains elusive. To understand how a chemical bonding of PbÀ X (covalency and ionicity) impact on growth of nanocrystals, we have examined two different halide perovskite nanocrystals of CsPbCl 3 (more ionic) and CsPbI 3 (more covalent) derived from the same parent CsPbBr 3 nanocrystals. Tracking the growth of nanocrystals by monitoring the spectral features of bulk peaks (at 445 nm for Cl and at 650 nm for I) enables us to determine the growth activation energy to be 92 kJ/mol (for CsPbCl 3 ) versus 71 kJ/mol (for CsPbI 3 ). The electronegativity of halides in PbÀ X bonds governs the bond strength (150-240 kJ/mol), characteristics of bonding (ionic versus covalent), and growth kinetics and resulting activation energies. A fundamental understanding of PbÀ X bonding provides a significant insight into controlling the size of the perovskite nanocrystals with more desired optoelectronic properties.

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