Effect of Calcination Temperatures on Surface Properties of Spinel ZnAl2O4 Prepared via the Polymeric Citrate Complex Method-Catalytic Performance in Glycerolysis of Urea.

In this study, we investigated urea glycerolysis over ZnAl2O4 catalysts that were prepared by using a citrate complex method and the influence of calcination temperatures on the surface properties of the prepared catalysts by varying the calcination temperature from 550 °C to 850 °C. As the reciprocal substitution between Al3+ and Zn2+ cations led to the formation of a disordered bulk ZnAl2O4 phase, different calcination temperatures strongly influenced the surface properties of the ZnAl2O4 catalysts, including oxygen vacancy. The increase in the calcination temperature from 550 °C to 650 °C decreased the inversion parameter of the ZnAl2O4 structure (from 0.365 to 0.222 for AlO4 and 0.409 to 0.358 for ZnO6). The disordered ZnAl2O4 structure led to a decrease in the surface acidity. The ZnAl2O4-550 catalyst had a large specific surface area, along with highly disordered surface sites, which increased surface acidity, resulting in a stronger interaction of the Zn NCO complex on its surface and an improvement in catalytic performance. Fourier transform infrared and thermogravimetric analysis results of the spent catalysts demonstrated the formation of a greater amount of a solid Zn NCO complex over ZnAl2O4-550 than ZnAl2O4-650. Consequently, the ZnAl2O4-550 catalyst outperformed the ZnAl2O4-650 catalyst in terms of glycerol conversion (72%), glycerol carbonate yield (33%), and byproduct formation.

Investigating the impact of TiO2 crystalline phases on catalytic properties of Ru/TiO2 for hydrogenolysis of polyethylene plastic waste.

A series of TiO2-supported Ru catalysts with different TiO2 crystalline phases was synthesized and employed for the hydrogenolysis of polyethylene (PE). CO chemisorption, high-angle annular dark-field-scanning transmission electron microscopy, temperature-programmed reduction, and CO-Fourier transform infrared spectroscopy suggested that the degree of strong metal-support interactions (SMSIs) varied depending on the type of the TiO2 phase and the reduction temperature, eventually influencing the catalysis of PE hydrogenolysis. Among the synthesized catalysts, Ru/TiO2 with the rutile phase (Ru/TiO2-R) exhibited the highest catalytic activity after high-temperature reduction at 500 °C, indicating that a certain degree of SMSI is necessary for ensuring high activity in PE hydrogenolysis. Ru/TiO2-R could be successfully employed for the hydrogenolysis of post-consumer plastic wastes such as LDPE bottles to produce valuable chemicals (liquid fuel and wax) in high yields of 74.7%. This work demonstrates the possibility of harnessing the SMSIs in the design and synthesis of active catalysts for PE hydrogenolysis.

High Seroprevalence of Anti-SARS-CoV-2 Antibodies in Children in Vietnam: An Observational, Hospital-Based Study.

Background: The robustness of sero-surveillance has delineated the high burden of SARS-CoV-2 infection in children; however, these existing data showed wide variation. This study aimed to identify the serostatus of antibodies against SARS-CoV-2 and associated factors among children following the fourth pandemic wave in Vietnam. Methods: A cross-sectional study was conducted at Vietnam National Children's Hospital (VNCH) between March 13 and April 3, 2022. Thus, 4032 eligible children seeking medical care for any medical condition not related to acute COVID-19 infection were tested for IgG SARS-CoV-2 antibodies by ADVIA Centaur® SARS-CoV-2 IgG (sCOVG) assay using the residuals of routine blood samples. Results: The median age of enrolled children was 39 (IQR = 14−82) months. The overall seropositive prevalence was 59.2% (95%CI = 57.6−60.7) and the median antibody titer was 4.78 (IQR 2.38−9.57) UI/mL. The risk of seropositivity and the median antibody titer were not related to gender (58.6% versus 60.1%, 4.9 versus 4.6 UI/mL, all p > 0.05). Children aged ≤12 months were likely to be seropositive compared to children aged 36 to <60 months (59.2% versus 57.5%, p = 0.49) and those aged ≥144 months (59.2% versus 65.5%, p = 0.16). Children aged ≥144 months exhibited a significantly higher titer of protective COVID-19 antibodies than other age groups (p < 0.001). In multivariate logistic regression, we observed independent factors associated with SARS-CoV-2 seropositivity, including the age 13 to <36 months (OR = 1.29, 95%CI = 1.06−1.56, p = 0.01), 60 to <144 months (OR = 0.79, 95%CI = 0.67−0.95, p = 0.01), ≥144 months (OR = 1.84, 95%CI = 1.21−2.8, p = 0.005), the presence of infected household members (OR = 2.36, 95%CI = 2.06−2.70, p < 0.001), participants from Hanoi (OR = 1.54, 95%CI = 1.34−1.77, p < 0.001), underlying conditions (OR = 0.71, 95%CI = 0.60−0.85, p ≤ 0.001), and using corticosteroids or immunosuppressants (OR = 0.64, 95%CI = 0.48−0.86, p = 0.003). Conclusions: This study highlights a high seroprevalence of antibodies against SARS-CoV-2 among children seeking medical care for non-acute COVID-19-related conditions in a tertiary children's hospital in Hanoi, Vietnam. In the context of reopening in-person schools and future emerging COVID-19 variants, this point will also be a key message about the necessity of "rush-out" immunization coverage for children, especially those under the age of five years.

17% Non-Fullerene Organic Solar Cells with Annealing-Free Aqueous MoO x.

A charge transport layer based on transition metal-oxides prepared by an anhydrous sol-gel method normally requires high-temperature annealing to achieve the desired quality. Although annealing is not a difficult process in the laboratory, it is definitely not a simple process in mass production, such as roll-to-roll, because of the inevitable long cooling step that follows. Therefore, the development of an annealing-free solution-processable metal-oxide is essential for the large-scale commercialization. In this work, a room-temperature processable annealing-free "aqueous" MoO x solution is developed and applied in non-fullerene PBDB-T-2F:Y6 solar cells. By adjusting the concentration of water in the sol-gel route, an annealing-free MoO x with excellent electrical properties is successfully developed. The PBDB-T-2F:Y6 solar cell with the general MoO x prepared by the anhydrous sol-gel method shows a low efficiency of 7.7% without annealing. If this anhydrous MoO x is annealed at 200 °C, the efficiency is recovered to 17.1%, which is a normal value typically observed in conventional structure PBDB-T-2F:Y6 solar cells. However, without any annealing process, the solar cell with aqueous MoO x exhibits comparable performance of 17.0%. In addition, the solar cell with annealing-free aqueous MoO x exhibits better performance and stability without high-temperature annealing compared to the solar cells with PEDOT:PSS.