Cycling stability of Fe2O3 nanosheets as supercapacitor sheet electrodes enhanced by MgFe2O4 nanoparticles.

The Fe2O3 material is a common active material for supercapacitor electrodes and has received much attention due to its cheap and easy availability and high initial specific capacitance. In the present study, we prepared adhesive-free Fe2O3 sheet electrodes for supercapacitors by growing Fe2O3 material on nickel foam by hydrothermal method. The sheet electrode exhibited a high initial specific capacitance of 863 F g-1, but we found that the sheet lost its specific capacitance too quickly through cyclic stability tests. To solve this problem, Fe2O3/MgFe2O4 composites were grown on nickel foam (NF). It was found through testing that the cycling stability of the sheet electrode gradually increased as the content of MgFe2O4 material increased. When the molar ratio of Fe2O3 to MgFe2O4 material was 1 : 1, the initial specific capacitance of the sheet electrode was 815 F g-1 and the capacitance remained at 81.25% of the initial specific capacitance after 1000 cycles. The better cycling stability results from the more stable structure of the composite, the synergistic effect leading to better reversibility of the reaction.

Racial and Ethnic Disparities in HIV Testing in People Who Use Drugs Admitted to a Tertiary Care Hospital.

Ending the HIV epidemic requires increased testing, diagnosis, and linkage to care. In the past 10 years, rates of HIV have increased among people with substance use disorder (SUD). HIV testing is recommended during hospitalization. Despite rising rates of infections and recommendations, HIV testing remains suboptimal. This study sought to detect differences in HIV testing by race and ethnicity in people who use drugs (PWUD) admitted to Tufts Medical Center (TuftsMC). This study is a retrospective review of hospitalized PWUD admitted from January 1, 2017 to December 31, 2020. PWUD were identified through toxicology results, medication prescribed for SUD, and nursing intake questions. The primary outcome of interest was whether an HIV test was ordered during hospitalization. The indicator of interest was race and ethnicity. Of 13,486 PWUD admitted to TuftsMC, only 10% had an HIV test ordered. Compared with White patients, Black patients [adjusted odds ratio (AOR): 0.69, 95% confidence interval (CI) (0.59-0.83)] and Hispanic patients [AOR: 0.68, 95% CI (0.55-0.84)] had decreased odds of receiving an HIV test. Our report is the first to show racial and ethnic differences in HIV testing ordering for hospitalized PWUD. Without access to harm reduction tools and expanded systems-based testing strategies, the HIV epidemic will continue and disproportionately impact minoritized communities.

Experimental study on the degradation mechanism of LaCoO3-based symmetric supercapacitors.

In this paper, LaCoO3 powders were prepared by the urea combustion method and used as electrode materials for supercapacitors. The effect of the potential window and the current density on the performance degradation of LaCoO3 electrodes during the cycling test was analyzed. The degradation mechanism of LaCoO3-based symmetric supercapacitors was discussed. The results of the cycling test show that: with the increase in potential window and current density, the performance degradation in the cycling test becomes more intense. The results of cyclic voltammetry tests, galvanostatic charge-discharge tests, X-ray photoelectron spectroscopy tests and KOH electrolyte concentration measurements before and after the cycling test show that the degradation of the supercapacitors is mainly caused by the occurrence and accumulation of irreversible redox reactions during the charge and discharge process, which reduces the ratio of Co2+/Co3+ and the number of oxygen vacancies.

Formation of bicyclic polycyclic aromatic hydrocarbons (PAHs) from the reaction of a phenyl radical with cis-3-penten-1-yne.

The formation of polycyclic aromatic hydrocarbons (PAHs) on the C11H11 potential energy surface involved in the reactions of a phenyl radical (C6H5) with cis-3-penten-1-yne (cis-C1H[triple bond, length as m-dash]C2-C3H[double bond, length as m-dash]C4H-C5H3, referred to as C5H6) and its three radicals (CH[triple bond, length as m-dash]C-C[double bond, length as m-dash]CH-CH3, CH[triple bond, length as m-dash]C-CH[double bond, length as m-dash]C-CH3, and cis-CH[triple bond, length as m-dash]C-CH[double bond, length as m-dash]CH-CH2, referred to as the C3-, C4-, and C5-radicals with the same chemical components, C5H5) assisted by H atoms is investigated by performing combined density functional theory (DFT) and ab initio calculations. Five potential pathways for the formation of PAHs have been explored in detail: Pathways I-II correspond to the reaction of C6H5 with C5H6 at the C1 and C2 position, and Pathways III-V involve the reaction of C6H5 with the C3-, C4-, and C5-radicals with the assistance of H atoms. The initial association of C6H5 with C5H6 or C5H5 is found to be highly exothermic with only minor barriers (1.4-7.1 kcal mol-1), which provides a large driving force for the formation of PAHs. The hydrogen atom is beneficial for the ring enlargement and ring formation processes. The present calculations predict 9 potential PAHs, six (CS6, CS10, CS13, CS26, CS28 and CS29) of which are indicated to be energetically more favorable along Pathways I, III, IV and V at low temperature. The calculated barriers for the formation of these PAHs are around 19.2-38.0 kcal mol-1. All PAHs products could be formed at flame temperature, for the medium barriers are easily overcome in various flame conditions. The theoretical results supplement the PAH formation pathway and provide help to understand PAH growth mechanism.