High-Performance Ultraviolet Photodetector Based on Graphene Quantum Dots Decorated ZnO Nanorods/GaN Film Isotype Heterojunctions.

A novel isotype heterojunction ultraviolet photodetector was fabricated by growing n-ZnO nanorod arrays on n-GaN thin films and then spin-coated with graphene quantum dots (GQDs). Exposed to UV illumination with a wavelength of 365 nm, the time-dependent photoresponse of the hybrid detectors manifests high sensitivity and consistent transients with a rise time of 100 ms and a decay time of 120 ms. Meanwhile, an ultra-high specific detectivity (up to ~ 1012 Jones) and high photoresponsivity (up to 34 mA W-1) are obtained at 10 V bias. Compared to the bare heterojunction detectors, the excellent performance of the GQDs decorated n-ZnO/n-GaN heterostructure is attributed to the efficient immobilization of GQDs on the ZnO nanorod arrays. GQDs were exploited as a light absorber and act like an electron donor to effectively improve the effective carrier concentration in interfacial junction. Moreover, appropriate energy band alignment in GQDs decorated ZnO/GaN hybrids can also be a potential factor in facilitating the UV-induced photocurrent and response speed.

Exploration of the relationship between disability perception, preference for death over disability, and suicidality in patients with acute and chronic pain.

HYPOTHESIS: Passive, active, and historical suicidality are associated with preference for death over disability. DESIGN: Community nonpatients without pain, community patients with pain, and patients with acute and chronic pain were compared for endorsement of disability perception and preference for death over disability. Phi correlations and chi-square analyses were calculated between preference for death over disability and six suicidality items representing passive, active, and historical suicidality. Logistic regression was used to predict preference for death over disability in patients with acute and chronic pain. RESULTS: For patients with acute and chronic pain, endorsement of preference for death over disability correlated significantly with all six suicidality items. The logistic regression models identified the following variables as predictors for preference for death over disability in patients with acute pain: the Behavior Health Inventory (BHI 2) family dysfunction scale, history of wanting to die, and disability perception. For patients with chronic pain, predictors were the BHI 2 Borderline scale, history of wanting to die, treated fairly by family item, frequent suicide ideation, people I trust turn on me item, and disability perception. Preference for death over disability was a statistically significant predictor in patients with chronic pain for disability perception, recent suicide ideation, having a suicidal plan, and a history of wanting to die but was not a significant predictor for any suicide items in patients with acute pain. CONCLUSION: Preference for death over disability is associated with passive and active suicide ideation and historical suicidality in patients with chronic pain.