Elucidating the Roles of Local and Nonlocal Rate Enhancement Mechanisms in Plasmonic Catalysis.

Plasmonic metal nanoparticles (e.g., Ag, Au, and Cu) constitute a class of materials that interact with light via the excitation of localized surface plasmon resonance (LSPR). Numerous studies have reported substantial enhancements in the rates of chemical reactions on illuminated plasmonic nanoparticle catalysts compared to corresponding systems in the absence of illumination. There are two mechanisms that have been proposed to explain the LSPR-induced chemical reactivity. One mechanism assumes a local plasmon-induced hot charge-carrier-mediated activation of the reactants, while the other assumes an LSPR-induced equilibrium heating of the catalyst, which leads to energy transfer to and chemical reaction of the adsorbed reactants. In this contribution, we developed a setup amenable to accurate in situ catalyst temperature and kinetic reaction rate measurements. We employed this setup to study the LSPR-induced rate enhancement in a case study of the CO oxidation reaction on plasmonic, monometallic Ag nanoparticle catalysts supported on α-Al2O3. We explored various Ag loadings and clustering levels. Our data show that the equilibrium heating of the catalyst cannot fully explain the illumination-induced plasmonic rate enhancements. This is the case even for high loading and clustering of Ag nanoparticles, where the equilibrium heating significantly increases. Based on the analysis, we propose that local effects, related to the plasmon-induced activation of adsorbates (reactants) via electronic excitation of the reactant or photothermal heating of the reactants that is highly localized to the individual nanoparticles, play a critical role in driving LSPR-induced chemical reactions.

Flow and extraction of energy and charge carriers in hybrid plasmonic nanostructures.

Strong interactions of electromagnetic fields with plasmonic nanomaterials have been exploited in various applications. These applications have centred on plasmon-enhanced scattering rates in nearby molecules or plasmon-induced heating. A question that has emerged recently is whether it is possible to use plasmonic nanostructures in a range of hot electron (hole) applications, including photocatalysis, photovoltaics and photodetection. These applications require coupling of a plasmonic component, which amplifies the interaction of light with the material, to an attached non-plasmonic component that extracts this energy in the form of electronic excitations to perform a function. In this Perspective, we discuss recent work in the emerging field of hybrid plasmonics. We focus on fundamental questions related to the nanoscopic flow of energy and excited charge carriers in these multicomponent materials. We also address critical misconceptions, challenges and opportunities that require more attention.

Adherence to prescription guidelines for medical cannabis in disability claimants.

OBJECTIVE: To examine a case series of 70 disability claimants who were referred to a clinic for multidisciplinary medical evaluation for physician compliance with cannabis prescription guidelines for pre-existing cannabis prescriptions. DESIGN: Retrospective case series analysis. SETTING: A private clinic in New Brunswick specializing in multidisciplinary medical assessment for institutional third-party insurers. PARTICIPANTS: All referrals for independent review of cannabis prescriptions between May 2016 and February 2018 (N = 70). MAIN OUTCOME MEASURES: Compliance with the cannabis prescription guidelines. RESULTS: Treating physicians were found to have not adhered to the guidelines in 53 of 61 patients (86.9%) who were prescribed cannabis products for pain management and in 8 of 9 patients (88.9%) who were prescribed cannabis products for treatment of posttraumatic stress disorder. Clinical assessment and radiologic review failed to identify a neuropathic cause of pain in 70.5% of pain cases. Adequate trials of noncannabinoid medications had not been attempted for 72.1% of patients with pain nor for any of the patients with posttraumatic stress disorder. Contraindications to cannabis were identified in 65.7% of cases, including evidence suggesting a past or present cannabis use disorder or currently active substance use disorder in 34.3% of cases. The prescriptions were found to be consistent with prescription guidelines in just 12.9% of cases. CONCLUSION: Very few of the reviewed cannabis prescriptions were found to be consistent with cannabis prescription guidelines. Respectful attention to guidelines might avoid unwarranted overprescribing, limit the secondary increase in comorbidity, and facilitate future scientific study and evaluation of medical cannabis.

Playing Russian Roulette: Parent and Adolescent Perspectives on Tumor Surveillance for Adolescents with Cancer Predisposition Syndromes.

PURPOSE: Cancer predisposition syndrome (CPS) surveillance allows for the early detection and treatment of neoplasms; however, the psychosocial impact of tumor surveillance is poorly understood for cancer-affected adolescents with a CPS and their parents. To gain insight, we qualitatively characterized the affective and cognitive experience of undergoing CPS tumor surveillance. EXPERIMENTAL DESIGN: Adolescents with a cancer history and their parents independently completed semi-structured interviews querying their experience with the adolescent's tumor surveillance. Interviews were coded using emotion coding and content analysis before developing themes using thematic analysis. RESULTS: Eight adolescents and 11 parents (7 mothers, 4 fathers) completed interviews. Parent themes included: maternal anxiety, relief following surveillance, fathers' positive expectations and emotions surrounding surveillance results, coping strategies, and perception of going through surveillance together with their child. Adolescent themes included: normalization of surveillance, indifference about surveillance but excitement to return to the hospital, focus on physical and logistic aspects, relief focused on being done with scans, and belief that outcomes would be good. Past scans/surveillance experiences influencing surveillance feelings was a theme across both parents and adolescents. CONCLUSIONS: Our findings suggest that tumor surveillance is not causing marked emotional distress for cancer-affected adolescents with a CPS. In contrast, mothers of cancer-affected adolescents undergoing surveillance may present with anxiety leading up to tumor surveillance and, for a subset, in between surveillance appointments. These observations highlight a need for ongoing psychosocial screening for families of children with a CPS and a role for psychosocial providers in multidisciplinary management of CPSs.