Influence of carbon support surface modification on the performance of nickel catalysts in carbon dioxide hydrogenation

The interaction between metal nanoparticles and a support is of key importance in catalysis. In this study, we demonstrate that the introduction of oxygen- or nitrogen-containing support surface groups on a graphite nanoplatelet support influence the performance of nickel supported catalysts during CO2 hydrogenation. By careful design of the synthesis conditions, the Ni nanoparticle size of the fresh catalysts was not affected by the type of support surface groups. A combination of H2 chemisorption and high resolution TEM demonstrates that the available metal surface depends on the interaction with the carbon support. The amination treatment results in the weakest interaction between the Ni and the support, showing the highest initial Ni weight-based activity, although at the expense of nanoparticle stability. Hence initial enhancement in activity is not always optimal for long term catalysis. The use of carbon with a higher density of oxygen functional groups that are stable above 350 °C, is beneficial for preventing deactivation due to particle growth. Furthermore, small amounts of contaminants can have a substantial influence on the CH4 selectivity at low conversions

Bone geometry and trabecular bone score in transgender people before and after short- and long-term hormonal treatment

Background: Gender-affirming hormonal treatment (HT) in adult transgender people influences bone mineral density (BMD). Besides BMD, bone geometry and trabecular bone score are associated with fracture risk. However, it is not known whether bone geometry and TBS changes during HT. Purpose: To investigate the bone geometry and TBS in adult transgender people at different time points, up to 25 years, of HT. Methods: A total of 535 trans women and 473 trans men were included, who were divided into three groups at time of their DXA: 20–29 years, 30–39 years, and 40–59 years. Subsequently, each group was divided into different HT durations: baseline, or after 5, 15, or 25 years of HT. Hip structure analysis was performed to measure subperiosteal width, endocortical diameter, average cortical thickness, and section modulus. TBS was calculated based on lumbar spine DXA images. Results: In trans women in all age groups and in young trans men, no differences were observed in periosteal width, endocortical diameter, average cortical thickness, and section modulus for different durations of HT. In trans men aged 40–59 years, subperiosteal width, endocortical diameter, and section modulus were slightly higher in the groups who were using HT compared to the (peri- or postmenopausal) baseline group. In younger trans women, TBS tended to be higher in those using HT compared to the baseline groups, and in older trans women TBS was higher in those using HT for 25 years versus baseline (+0.04, 95%CI +0.00; +0.08). In younger trans men, TBS tended to be lower in those who used HT compared to the baseline groups, and in older trans men TBS was lower in those using 5 years HT versus baseline (−0.05, 95%CI −0.08; −0.01). Conclusion: No differences in cortical bone geometry parameters were found during different HT-durations. TBS increased in trans women and decreased in trans men, indicating that estrogens have positive effects on TBS. These data may be helpful in determining what sex reference values for calculating T-scores and Z-scores in adult transgender people should be used

Fracture risk in trans women and trans men using long-term gender-affirming hormonal treatment: a nationwide cohort study

Concerns about bone health in transgender people using gender-affirming hormonal treatment (HT) exist, but the fracture risk is not known. In this nationwide cohort study, we aimed to compare the fracture incidence in transgender people using long-term HT with an age-matched reference population. All adult transgender people who started HT before 2016 at our gender-identity clinic were included and were linked to a random population-based sample of 5 age-matched reference men and 5 age-matched reference women per person. Fracture incidence was determined using diagnoses from visits to hospital emergency rooms nationwide between 2013 and 2015. A total of 1089 trans women aged <50 years (mean 38 ± 9 years) and 934 trans women aged ≥50 years (mean 60 ± 8 years) using HT for median 8 (interquartile range [IQR] 3–16) and 19 (IQR 11–29) years, respectively, were included. A total of 2.4% of the trans women aged <50 years had a fracture, whereas 3.0% of the age-matched reference men (odds ratio [OR] = 0.78, 95% confidence interval [CI] 0.51–1.19) and 1.6% of the age-matched reference women (OR = 1.49, 95% CI 0.96–2.32) experienced a fracture. In trans women aged ≥50 years, 4.4% experienced a fracture compared with 2.4% of the age-matched reference men (OR = 1.90, 95% CI 1.32–2.74) and 4.2% of the age-matched reference women (OR = 1.05, 95% CI 0.75–1.49). A total of 1036 trans men (40 ± 14 years) using HT for median 9 (IQR 2–22) years were included. Fractures occurred in 1.7% of the trans men, 3.0% of the age-matched reference men (OR = 0.57, 95% CI 0.35–0.94), and 2.2% of the age-matched reference women (OR = 0.79, 95% CI 0.48–1.30). In conclusion, fracture risk was higher in older trans women compared with age-matched reference men. In young trans women, fracture risk tended to be increased compared with age-matched reference women. Fracture risk was not increased in young trans men

Copper sulfide derived nanoparticles supported on carbon for the electrochemical reduction of carbon dioxide

The electrocatalytic reduction of CO2 to produce sustainable fuels and chemicals is attracting great attention. Cu-based catalysts can lead to the production of a range of different molecules, and interestingly the product selectivity strongly depends on the preparation history, although it is not fully understood yet why. We report a novel strategy that allowed us to prepare Cu nanoparticle on carbon catalysts with similar morphologies, but prepared by in-situ reduction of either supported CuS, Cu2S or CuO nanoparticles. For the first time the evolution of the Cu species was followed under CO2 and H+ reduction conditions using in-situ X-ray absorption spectroscopy. Excellent electrochemical contact between the Cu-based nanoparticles, the carbon support and the carbon-paper substrate was observed, resulting in metallic Cu as the predominant phase under typical electrochemical CO2 reduction conditions. Even covering less than 4% of the H2 producing carbon support with Cu-sulfide derived nanoparticles allowed to steer the selectivity to a maximum of 12% Faradaic efficiency for the production of formate. Clear differences between the catalysts derived from CuS, Cu2S or CuO nanoparticles were observed, which was ascribed to the presence of residual sulfur in the catalysts

Copper sulfide derived nanoparticles supported on carbon for the electrochemical reduction of carbon dioxide

The electrocatalytic reduction of CO2 to produce sustainable fuels and chemicals is attracting great attention. Cu-based catalysts can lead to the production of a range of different molecules, and interestingly the product selectivity strongly depends on the preparation history, although it is not fully understood yet why. We report a novel strategy that allowed us to prepare Cu nanoparticle on carbon catalysts with similar morphologies, but prepared by in-situ reduction of either supported CuS, Cu2S or CuO nanoparticles. For the first time the evolution of the Cu species was followed under CO2 and H+ reduction conditions using in-situ X-ray absorption spectroscopy. Excellent electrochemical contact between the Cu-based nanoparticles, the carbon support and the carbon-paper substrate was observed, resulting in metallic Cu as the predominant phase under typical electrochemical CO2 reduction conditions. Even covering less than 4% of the H2 producing carbon support with Cu-sulfide derived nanoparticles allowed to steer the selectivity to a maximum of 12% Faradaic efficiency for the production of formate. Clear differences between the catalysts derived from CuS, Cu2S or CuO nanoparticles were observed, which was ascribed to the presence of residual sulfur in the catalysts