Photo-Stabilisation and UV Blocking Efficacy of Coated Macro and Nano-Rutile Titanium Dioxide Particles in Paints and Coatings

Surface treated macro and nanoparticle TiO2samples have been prepared, characterised and their efficiency as UV blockers evaluated in clear coatings and paints. The particle size of the ‘base’ TiO2has been optimised to block UV radiation and the surface treatment developed to deactivate the photocatalytic activity of the surface of the TiO2particles. The resultant UV blockers have been evaluated in both solvent and water-based clear coatings. Nanoparticle TiO2has been prepared from ‘seed’ and the particle size was controlled by calcination. It was found that the choice of particle size is a compromise between UVA absorption, UVB absorption, visible transmission and photoactivity. It has been demonstrated that TiO2with a crystallite size of 25 nm yields a product with the optimum properties. A range of dispersants was successfully used to disperse and mill the TiO2. Both organic and inorganic dispersants were used; 2-amino-2-methyl-1-propanol and 1-amino-2-propanol (MIPA) and P2O5and Na2SiO3respectively. The surface of the nano-TiO2was coated with mixed oxides of silicon, aluminium, zirconium and phosphorous. Addition of the resultant coated nano-rutiles to an Isocyanate Acrylic clear coating prolonged the lifetime of that coating compared to the blank. Generally, a surface treatment based on SiO2, Al2O3and P2O5was more successful than one based on ZrO2, Al2O3and P2O5. Higher addition levels of the surface treatment were beneficial for protecting the polymeric coating. The UV blocker products were also evaluated in a water-based acrylic, first a water-based dispersion of the UV blocker was prepared before addition to the acrylic. The dispersions and resultant acrylic thin films were evaluated using UV/Vis spectroscopy and durability assessed. The ratio of absorbance at 300:500 nm for the water-based dispersion was shown to be a good predictor of both the transparency of the resultant acrylic thin film and the durability of that film, in terms of weight loss. Macro grade titanium dioxide pigments were also prepared and coated with treatments of silica, alumina and siloxane and their photo-stabilising activity in alkyd paint film assessed and found to be directly related to the electron–hole pair mobility and trapping as determined by micro-wave spectroscopy

Harder-to-reach people living with HIV experiencing high prevalence of all-type mental health disorder diagnosis.

People living with HIV/AIDS (PHA) often concurrently cope with mental health disorders that may greatly influence HIV and other health-related outcomes. The objective of this study was to examine the prevalence and correlates of self-reported mental health disorder diagnosis among a cohort of harder-to-reach HIV-positive individuals in British Columbia, Canada. Between 2007 and 2010, 1000 PHA who had initiated ART were enrolled in the Longitudinal Investigation into Supportive and Ancillary health services (LISA) study. Socio-demographic, behavioral, health-care utilization and psychosocial information was collected through interviewer-led questionnaires and linked to longitudinal clinical variables through the provincial Drug Treatment Program at the BC Centre for Excellence in HIV/AIDS. We identified the prevalence of all-type and specific mental health disorders among this population. Of the 916 participants included in this analysis, 494 (54%) reported ever having a mental health disorder diagnosis. Mood (85%) and anxiety (65%) disorders were the two most frequently reported mental health conditions. Self-reported all-type mental health disorder was independently associated with decreased overall functioning (adjusted odds ratio [AOR] = 0.90, 95% confidence interval [CI] = 0.83-0.98) and life satisfaction (AOR = 0.81, 95% CI = 0.74-0.89), and having higher stigma score (AOR = 1.11, 95%CI = 1.02-1.21). Participants reporting any mental health disorder were more likely to report a history of sexual assault (AOR = 2.45, 95% CI = 1.75-3.43) and to have used case management services (AOR = 1.63, 95%CI = 1.17-2.27). Our findings uncovered a high burden of mental health disorders among harder-to-reach PHA and suggest that PHA with at least one mental health disorder diagnosis are disproportionately impacted by sexual violence and stigma