An Integrative Review of the Feasibility and Effects of the Use of Location-Tracking Devices by Persons Living With Cognitive Impairment.

OBJECTIVES: This study aimed to examine the effects of location-tracking devices on persons living with cognitive impairment, investigate facilitators of and barriers to using the devices, and provide future directions for the use of the devices. METHODS: An integrative review was conducted using 5 databases: PubMed, Embase, Web of Science, CINAHL, and Scopus. From the 1429 initially identified studies, 10 were included in the review. RESULTS: Location-tracking devices benefited persons living with cognitive impairment and their informal caregivers. The devices brought more independence to persons living with cognitive impairment, allowing them to go outside and feel safer there. Furthermore, the devices reduced the caregivers' worries about their loved ones being lost. CONCLUSIONS: Location-tracking devices have the potential to increase independence in persons living with cognitive impairment and to decrease psychological stress in informal caregivers. In the future, ways to minimize the barriers to using location-tracking devices need to be determined.

Influence of caregivers' psychological well-being on the anxiety and depression of care recipients with dementia.

This study was conducted to examine how caregivers' psychological well-being influences the anxiety or depression of care recipients with dementia. A secondary data analysis was conducted using 666 dyads of older adults with dementia and their caregivers. The odds that care recipients with dementia would experience anxiety increased when caregivers had a negative relationship with care recipients (OR = 1.22, p = 0.042), lower perception of the positive aspects of caregiving (OR = 0.86, p = 0.047), or anxiety (OR = 2.41, p = 0.036). The odds that care recipients with dementia would experience depression increased when caregivers had a greater perception of the negative aspects of caregiving (OR = 1.15, p = 0.023) or anxiety (OR = 2.21, p = 0.045). Since care recipients with dementia and their caregivers spend considerable time together daily, caregivers' psychological well-being can impact care recipients' anxiety and depression.

Light-Driven Ammonia Production by Azotobacter vinelandii Cultured in Medium Containing Colloidal Quantum Dots.

There is an evergrowing demand for environment-friendly processes to synthesize ammonia (NH3) from atmospheric nitrogen (N2). Although diazotrophic N2 fixation represents an undeniably "green" process of NH3 synthesis, the slow reaction rate makes it less suitable for industrially meaningful large-scale production. Here, we report the photoinduced N2 fixation using a hybrid system composed of colloidal quantum dots (QDs) and aerobic N2-fixing bacteria, Azotobacter vinelandii. Compared to the case where A. vinelandii cells are simply mixed with QDs, NH3 production increases significantly when A. vinelandii cells are cultured in the presence of core/shell InP/ZnSe QDs. During the cell culture of A. vinelandii, the cellular uptake of QDs is facilitated in the exponential growth phase. Experimental results as well as theoretical calculations indicate that the photoexcited electrons in QDs within A. vinelandii cells are directly transferred to MoFe protein, the catalytic component of nitrogenase. We also observe that the excess amount of QDs left on the outer surface of A. vinelandii disrupts the cellular membrane, leading to the decrease in NH3 production due to the deactivation of nitrogenase. The successful uptake of QDs in QD-A. vinelandii hybrid with minimal amount of QDs on the outer surface of the bacteria is key to efficient photosensitized NH3 production. The comprehensive understanding of the QD-bacteria interface paves an avenue to novel and efficient nanobiohybrid systems for chemical production.

Enhanced optical absorption in conformally grown MoS2 layers on SiO2/Si substrates with SiO2 nanopillars with a height of 50 nm.

The integration of transition metal dichalcogenide (TMDC) layers on nanostructures has attracted growing attention as a means to improve the physical properties of the ultrathin TMDC materials. In this work, the influence of SiO2 nanopillars (NPs) with a height of 50 nm on the optical characteristics of MoS2 layers is investigated. Using a metal organic chemical vapor deposition technique, a few layers of MoS2 were conformally grown on the NP-patterned SiO2/Si substrates without notable strain. The photoluminescence and Raman intensities of the MoS2 layers on the SiO2 NPs were larger than those observed from a flat SiO2 surface. For 100 nm-SiO2/Si wafers, the 50 nm-NP patterning enabled improved absorption in the MoS2 layers over the whole visible wavelength range. Optical simulations showed that a strong electric-field could be formed at the NP surface, which led to the enhanced absorption in the MoS2 layers. These results suggest a versatile strategy to realize high-efficiency TMDC-based optoelectronic devices.

Vertically-Oriented WS2 Nanosheets with a Few Layers and Its Raman Enhancements.

Vertically-oriented two-dimensional (2D) tungsten disulfide (WS2) nanosheets were successfully grown on a Si substrate at a temperature range between and 550 °C via the direct chemical reaction between WCl6 and S in the gas phase. The growth process was carefully optimized by adjusting temperature, the locations of reactants and substrate, and carrier gas flow. Additionally, vertically-oriented 2D WS2 nanosheets with a few layers were tested as a surface-enhanced Raman scattering substrate for detecting rhodamine 6G (R6G) molecules where enhancement occurs from chemical enhancement by charge transfer transition from semiconductor). Raman spectra of R6G molecules adsorbed on vertically-oriented 2D WS2 nanosheets exhibited strong Raman enhancement effects up to 9.2 times greater than that on the exfoliated WS2 monolayer flake sample. From our results, we suggest that the WS2 nanosheets can be an effective surface-enhanced Raman scattering substrate for detecting target molecules.

Study of Chemical Enhancement Mechanism in Non-plasmonic Surface Enhanced Raman Spectroscopy (SERS).

Surface enhanced Raman spectroscopy (SERS) has been intensively investigated during the past decades for its enormous electromagnetic field enhancement near the nanoscale metallic surfaces. Chemical enhancement of SERS, however, remains rather elusive despite intensive research efforts, mainly due to the relatively complex enhancing factors and inconsistent experimental results. To study details of chemical enhancement mechanism, we prepared various low dimensional semiconductor substrates such as ZnO and GaN that were fabricated via metal organic chemical vapor deposition process. We used three kinds of molecules (4-MPY, 4-MBA, 4-ATP) as analytes to measure SERS spectra under non-plasmonic conditions to understand charge transfer mechanisms between a substrate and analyte molecules leading to chemical enhancement. We observed that there is a preferential route for charge transfer responsible for chemical enhancement, that is, there exists a dominant enhancement process in non-plasmonic SERS. To further confirm our idea of charge transfer mechanism, we used a combination of 2-dimensional transition metal dichalcogenide substrates and analyte molecules. We also observed significant enhancement of Raman signal from molecules adsorbed on 2-dimensional transition metal dichalcogenide surface that is completely consistent with our previous results. We also discuss crucial factors for increasing enhancement factors for chemical enhancement without involving plasmonic resonance.

Direct observation of quantum tunnelling charge transfers between molecules and semiconductors for SERS.

We used high-quality ZnO nanostructures/graphene substrates for understanding the mechanisms of charge transfer (CT) that take place under nonplasmonic conditions. As the optimal conditions for CT processes are found, we studied the range of CT normal to the ZnO surface that is coated with nanoscale HfO2 layers with different thicknesses. We could observe that CT decays over a few nanometers. In addition, we also observed a unique oscillation of the SERS intensity in the atomically thin oxide layers, which reflects the quantum tunneling effects of CT electrons across the oxide layers. To the best of our knowledge, this is the first direct observation of SERS-active charge transport and measurement of a CT span with atomic-scale accuracy.