Experimental measurement and modelling of reactive species generation in TiO2 nanoparticle photocatalysis.

The generation of reactive species in titanium dioxide (TiO2) nanoparticle photocatalysis was assessed in a laboratory scale setup, in which P25 Aeroxide TiO2 suspensions were photoactivated by means of UV-A radiation. Photogenerated holes and hydroxyl radicals were monitored over time by observing their selective reaction with probe compounds, iodide and terephthalic acid, respectively. TiO2 aggregate size and structure were characterized over the reaction time. Reactive species quenching was then described by a model, accounting for radiative phenomena, TiO2 nanoparticle aggregation and kinetic reactions. The interaction between iodide and photogenerated holes was influenced by iodide adsorption on TiO2 surface, described by a Langmuir-Hinshelwood mechanism, whose parameters were studied as a function of TiO2 concentration and irradiation time. Iodide oxidation was effectively simulated by modelling the reaction volume as a completely stirred two-dimensional domain, in which irradiation phenomena were described by a two-flux model and the steady state for reactive species was assumed. The kinetic parameters for iodide adsorption and oxidation were estimated and successfully validated in a different experimental setup. The same model was adapted to describe the oxidation of terephthalic acid by hydroxyl radicals. The kinetic parameters for terephthalic acid oxidation were estimated and validated, while the issues in investigating the interaction mechanisms among the involved species have been discussed. The sensitivity of operating parameters on model response was assessed and the most relevant parameters were highlighted.

Delirium in Patients with SARS-CoV-2 Infection: A Multicenter Study.

OBJECTIVES: The aims of this study are to report the prevalence of delirium on admission to the unit in patients hospitalized with SARS-CoV-2 infection, to identify the factors associated with delirium, and to evaluate the association between delirium and in-hospital mortality. DESIGN: Multicenter observational cohort study. SETTINGS: Acute medical units in four Italian hospitals. PARTICIPANTS: A total of 516 patients (median age 78 years) admitted to the participating centers with SARS-CoV-2 infection from February 22 to May 17, 2020. MEASUREMENTS: Comprehensive medical assessment with detailed history, physical examinations, functional status, laboratory and imaging procedures. On admission, delirium was determined by the Diagnostic and Statistical Manual of Mental Disorders (5th edition) criteria, 4AT, m-Richmond Agitation Sedation Scale, or clinical impression depending on the site. The primary outcomes were delirium rates and in-hospital mortality. RESULTS: Overall, 73 (14.1%, 95% confidence interval (CI) = 11.0-17.3%) patients presented delirium on admission. Factors significantly associated with delirium were dementia (odds ratio, OR = 4.66, 95% CI = 2.03-10.69), the number of chronic diseases (OR = 1.20, 95% CI = 1.03; 1.40), and chest X-ray or CT opacity (OR = 3.29, 95% CI = 1.12-9.64 and 3.35, 95% CI = 1.07-10.47, for multiple or bilateral opacities and single opacity vs no opacity, respectively). There were 148 (33.4%) in-hospital deaths in the no-delirium group and 43 (58.9%) in the delirium group (P-value assessed using the Gray test <.001). As assessed by a multivariable Cox model, patients with delirium on admission showed an almost twofold increased hazard ratio for in-hospital mortality with respect to patients without delirium (hazard ratio = 1.88, 95% CI = 1.25-2.83). CONCLUSION: Delirium is prevalent and associated with in-hospital mortality among older patients hospitalized with SARS-CoV-2 infection.

Specific and total N-nitrosamines formation potentials of nitrogenous micropollutants during chloramination.

N-nitrosamines are a group of potent human carcinogens that can be formed during oxidative treatment of drinking water and wastewater. Many tertiary and quaternary amines present in consumer products (e.g., pharmaceuticals, personal care and household products) are known to be N-nitrosodimethylamine (NDMA) precursors during chloramination, but the formation of other N-nitrosamines has been rarely studied. This study investigates the specific and total N-nitrosamine (TONO) formation potential (FP) of various precursors from nitrogen-containing micropollutants (chlorhexidine, metformin, benzalkonium chloride and cetyltrimethylammonium chloride) and tertiary and quaternary model amines (trimethyl amine, N,N-dimethylbutyl amine, N,N-dimethylbenzyl amine and tetramethyl ammonium). All the studied nitrogenous micropollutants displayed quantifiable TONO FP, with molar yields in the range 0.04-11.92%. However, the observed TONO pools constituted mostly of uncharacterized species, not included in US-EPA 8270 N-nitrosamines standard mix. Only the quaternary ammonium compound benzalkonium chloride showed quantifiable NDMA FP (0.56% molar yield), however, explaining only a minor fraction of the observed TONO FP. The studied model amines showed molar NDMA yields from 0.10% (trimethyl amine) to 5.05% (N,N-dimethylbenzyl amine), very similar to the molar TONO yields. The comparison of the FPs of micropollutants and model compounds showed that the presence of electron donating functional groups (such as a benzyl group) in tertiary and quaternary amine precursors leads to a higher formation of NDMA and uncharacterized N-nitrosamines, respectively. LC-qTOF screening of a list of proposed N-nitrosamine structures has enabled to identify a novel N-nitrosamine (N-nitroso-N-methyldodecylamine) from the chloramination of benzalkonium chloride. This finding supports the hypothesis that different functional groups in quaternary amines can act as leaving groups during chloramination and form differing N-nitrosamine structures at significant yield. Molar TONO yields determined for micropollutants were finally validated under experimental conditions closer to real water matrices, confirming their representativeness also for lower concentration ranges.