Metastable Ni(I)-TiO _2-x Photocatalysts: Self-Amplifying H₂ Evolution from Plain Water without Noble Metal Co-Catalyst and Sacrificial Agent

Decoration of semiconductor photocatalysts with cocatalysts is generally done by a step-by-step assembly process. Here, we describe the self-assembling and self-activating nature of a photocatalytic system that forms under illumination of reduced anatase TiO2 nanoparticles in an aqueous Ni2+ solution. UV illumination creates in situ a Ni+/TiO2/Ti3+ photocatalyst that self-activates and, over time, produces H-2 at a higher rate. In situ X-ray absorption spectroscopy and electron paramagnetic resonance spectroscopy show that key to self-assembly and self-activation is the light-induced formation of defects in the semiconductor, which enables the formation of monovalent nickel (Ni+) surface states. Metallic nickel states, i.e., Ni-0, do not form under the dark (resting state) or under illumination (active state). Once the catalyst is assembled, the Ni+ surface states act as electron relay for electron transfer to form H-2 from water, in the absence of sacrificial species or noble metal cocatalysts.Web of Science14548261322612

Temporal Trends in Overweight and Obesity, Physical Activity and Screen Time among Czech Adolescents from 2002 to 2014: A National Health Behaviour in School-Aged Children Study

This study examines trends in overweight and obesity, physical activity (PA) and screen time (ST) among Czech adolescents over a recent 12-year study period. Nationally representative samples consisted of 19,940 adolescents (9760 boys and 10,180 girls) aged 10.5–16.5 years from the Czech Health Behaviour in School-aged Children (HBSC) questionnaire-based surveys conducted in 2002, 2006, 2010 and 2014. Trends in the prevalence of overweight/obesity, meeting the recommendations for moderate-to-vigorous PA (MVPA) (≥60 min per day of MVPA) and excessive ST (>2 h per day) were estimated using logistic regression. Significant increases (p < 0.001) in the prevalence of overweight/obesity between the years 2002 and 2014 were evident for both adolescent boys (18.3%2002–24.8%2014) and girls (8.3%2002–11.9%2014). Compared to 2002, in 2014 significant decreases (p < 0.001) in meeting MVPA recommendations were observed among boys (32.2%2002–25.6%2014) and girls (23.2%2002–19.2%2014). Moreover, in boys we observed significant increases (p < 0.001) in excessive ST on weekdays (75.1%2002–88.8%2014), as well as on weekends (78.3%2002–91.9%2014) between the years 2002 and 2014. Increases in overweight/obesity with concomitant decreases in PA provide evidence in support of the current and upcoming efforts of government and commercial organizations in implementing interventions aimed at reducing excessive body weight among Czech adolescents

Test-retest reliability of survey items on ownership and use of physical activity trackers

Background: Researchers are interested in using digital tools, such as physical activity trackers (PAT), to promote and measure physical activity. PAT is a fast-growing research area that measures movement therefore, reliable questions on the ownership and use of PATs among adolescent populations need to be developed. Objective: The aim of this study was to conduct an intra-rater test-retest reliability study on PAT survey items used for surveillance purposes among young adolescents in ownership and use of smartphone applications (apps) and heart rate monitors (HRM). Methods: Young adolescents (N = 755; 11-, 13-, and 15-year-olds) in the Olomouc region of the Czech Republic were recruited to complete the questionnaire with a three-week gap during autumn 2017. Kappa statistics were used for measuring reliability. Results: When items were dichotomised into owners and non-owners, there was moderate agreement for boys (apps Kappa = .563, HRM Kappa = .575) and girls (apps Kappa = .447, HRM Kappa = .443).Conclusions: Measures in ownership and use of PAT can be assumed reliable among young adolescents

Trends and correlates of overweight/obesity in Czech adolescents in relation to family socioeconomic status over a 12-year study period (2002–2014)

Abstract Background This study examined a) trends in overweight/obesity, moderate-to-vigorous physical activity (MVPA), and screen time (ST) among Czech adolescents over a 12-year study period (2002–2014) in relation to family affluence (FA) and b) correlates of adolescent overweight/obesity from different FA categories. Methods A nationally representative sample of 18,250 adolescents (51.4% girls) aged 10.5–16.5 years was drawn from the Czech Health Behaviour in School-aged Children questionnaire-based surveys in 2002, 2006, 2010, and 2014. Using the FA scale, the socioeconomic status (SES) of the respondents’ families was assessed. SES-stratified trends in the prevalence of overweight/obesity meeting the MVPA (≥60 min/day), and ST (≤2 h/day) recommendations were assessed using logistic regression. Results A trend-related significant increase (p < 0.05) in the prevalence of overweight/obesity was observed in low−/medium-FA boys and medium−/high-FA girls. Unlike in high-FA adolescents, a significant decrease was revealed in the rates of meeting the MVPA recommendation in low-FA boys (28.9%2002 → 23.3%2014, OR = 0.75, 95% CI = 0.59–0.95, p < 0.05) and girls (22.3%2002 → 17.3%2014, OR = 0.73, 95% CI = 0.57–0.92, p < 0.01). A significant (p < 0.001) trend-related increase in excessive ST was evident in adolescents regardless of gender and FA category. Generally, girls and older adolescents had lower odds of overweight/obesity than boys and 11-year-old adolescents. While in the high-FA category of adolescents, achieving 60 min of MVPA daily and the absence of excessive ST on weekdays significantly (p < 0.01) reduced their odds of being overweight/obese, in low-FA adolescents this was not the case. Conclusions High rates of overweight/obesity and a poor level of daily MVPA among low-FA children provide disturbing evidence highlighting the necessity of public health efforts to implement obesity reduction interventions for this disadvantaged population

Fluorine Aided Stabilization of Pt Single Atoms on TiO2_2 Nanosheets and Strongly Enhanced Photocatalytic H2_2 Evolution

Trapping sites in single atom (SA) catalysts are critical to the stabilization and reactivity of isolated atoms. Herein, we show that anchoring of Pt SAs on TiO$_2$ nanosheets is strongly aided by lattice incorporated fluorine species. Tailoring the speciation of fluorine on TiO$_2$ nanosheets is a key factor for uniform and stable dispersion of the Pt SAs and high efficiency in Pt SA co-catalyzed photocatalytic H$_2$ production. Fluorine-stabilized uniformly dispersed Pt SAs on the (001) surface of TiO$_2$ can provide a remarkable photocatalytic activity (a H$_2$ production rate of 45.3 mmol h$^{–1}$ mg$^{–1}$ Pt for 65 mW/cm2 365 nm light). This high (maximized) efficiency can be achieved with a remarkably low loading amount of Pt SAs on TiO$_2$ nanosheets (0.03 wt %), which is far superior to Pt nanoparticles on a TiO$_2$ nanosheet with the same or a higher loading amount. F-stabilized Pt SAs on TiO$_2$ nanosheets also exhibit an excellent stability in long-term photocatalytic reactions

Fluorine Aided Stabilization of Pt Single Atoms on TiO2_{2} Nanosheets and Strongly Enhanced Photocatalytic H2_{2} Evolution

Trapping sites in single atom (SA) catalysts are critical to the stabilization and reactivity of isolated atoms. Herein, we show that anchoring of Pt SAs on TiO$_2$ nanosheets is strongly aided by lattice incorporated fluorine species. Tailoring the speciation of fluorine on TiO$_2$ nanosheets is a key factor for uniform and stable dispersion of the Pt SAs and high efficiency in Pt SA co-catalyzed photocatalytic H$_2$ production. Fluorine-stabilized uniformly dispersed Pt SAs on the (001) surface of TiO$_2$ can provide a remarkable photocatalytic activity (a H$_2$ production rate of 45.3 mmol h$^{–1}$ mg$^{–1}$ Pt for 65 mW/cm2 365 nm light). This high (maximized) efficiency can be achieved with a remarkably low loading amount of Pt SAs on TiO$_2$ nanosheets (0.03 wt %), which is far superior to Pt nanoparticles on a TiO$_2$ nanosheet with the same or a higher loading amount. F-stabilized Pt SAs on TiO$_2$ nanosheets also exhibit an excellent stability in long-term photocatalytic reactions

Typologies of joint family activities and associations with mental health and wellbeing among adolescents from four countries

Purpose This study aims to identify distinct typologies of joint family activities and the associations with mental health and wellbeing among adolescents across four countries from the World Health Organization European region. Methods The 2017/2018 data from adolescents from Armenia (n = 3,977, Mage = 13.5 ± 1.6 years, 53.4% female), Czechia (n = 10,656, Mage = 13.4 ± 1.7, 50.1% female), Russia (n = 4,096, Mage = 13.8 ± 1.7, 52.4% female), and Slovakia (n = 3,282, Mage = 13.4 ± 1.5, 51.0% female) were collected in schools. The respondents self-reported their participation in joint family leisure-time activities, life satisfaction, psychological and somatic complaints, as well as a range of demographic and family situational factors. Stratified by countries, latent class analysis identified typologies of joint family activities, and logistic regression models explored cross-sectional associations with life satisfaction, and psychological and somatic complaints. Results Three typologies were identified across each of the four countries, distinguished by low, moderate, and high levels of family engagement. Adolescents with higher family engagement generally reported greater life satisfaction and fewer psychological complaints compared to those with lower family engagement. Russian adolescents in the high family engagement typology reported fewer somatic complaints compared to those with low family engagement. In addition, adolescents from Czechia and Russia showing moderate family engagement also reported fewer psychological complaints compared to those in the low family engagement typology. Discussion Our findings from four countries suggest that adolescents with high family engagement have greater life satisfaction and fewer psychological complaints, pointing toward a need for interventions to support family engagement among adolescents. Further research is needed to fully explore underlying mechanisms. </p

As a single atom Pd outperforms Pt as the most active co-catalyst for photocatalytic H-2 evolution

Here, we evaluate three different noble metal co-catalysts (Pd, Pt, and Au) that are present as single atoms (SAs) on the classic benchmark photocatalyst, TiO2. To trap the single atoms on the surface, we introduced controlled surface vacancies (Ti3+-Ov) on anatase TiO2 nanosheets by a thermal reduction treatment. After anchoring identical loadings of single atoms of Pd, Pt, and Au, we measure the photocatalytic H-2 generation rate and compare it to the classic nanoparticle co-catalysts on the nanosheets. While nanoparticles yield the well-established the hydrogen evolution reaction activity sequence (Pt &gt; Pd &gt; Au), for the single atom form, Pd radically outperforms Pt and Au. Based on density functional theory (DFT), we ascribe this unusual photocatalytic co-catalyst sequence to the nature of the charge localization on the noble metal SAs embedded in the TiO2 surface

Fluorine Aided Stabilization of Pt Single Atoms on TiO₂ Nanosheets and Strongly Enhanced Photocatalytic H₂ Evolution

Trapping sites in single atom (SA) catalysts are critical to the stabilization and reactivity of isolated atoms. Herein, we show that anchoring of Pt SAs on TiO2 nanosheets is strongly aided by lattice incorporated fluorine species. Tailoring the speciation of fluorine on TiO2 nanosheets is a key factor for uniform and stable dispersion of the Pt SAs and high efficiency in Pt SA co-catalyzed photocatalytic H2 production. Fluorine-stabilized uniformly dispersed Pt SAs on the (001) surface of TiO2 can provide a remarkable photocatalytic activity (a H2 production rate of 45.3 mmol h–1 mg–1 Pt for 65 mW/cm2 365 nm light). This high (maximized) efficiency can be achieved with a remarkably low loading amount of Pt SAs on TiO2 nanosheets (0.03 wt %), which is far superior to Pt nanoparticles on a TiO2 nanosheet with the same or a higher loading amount. F-stabilized Pt SAs on TiO2 nanosheets also exhibit an excellent stability in long-term photocatalytic reactions