Bimodal Mesoporous Titanium Nitride/Carbon Microfibers as Efficient and Stable Electrocatalysts for Li–O_2 Batteries

The rechargeable Li–O_2 battery has been considered as a sustainable chemical power source for electric vehicles and grid energy storage systems due to the high theoretical specific energy (∼3500 Wh/kg). The practical performance of Li–O_2 batteries is, however, still far below expectations. This is mainly attributed to the (1) intrinsic sluggish reaction kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), (2) passivation of the electrodes by electrical isolation and pore blocking, and (3) chemical instability of the organic cell components, i.e., electrolyte, polymer binder, and carbon electrode, in the presence of O_2•– and Li_2O_2. It is crucial to develop highly porous, three-dimensional, conducting cathode catalyst/gas diffusion layer (GDL) architectures possessing superior catalytic activity and stability with respect to the ORR and the OER in order to address these issues. All of these requirements prompted us to examine the catalytic performance of porous framework metal nitride electrodes for Li–O_2 batteries

CT694 and pgp3 as Serological Tools for Monitoring Trachoma Programs.

Defining endpoints for trachoma programs can be a challenge as clinical signs of infection may persist in the absence of detectable bacteria. Antibody-based tests may provide an alternative testing strategy for surveillance during terminal phases of the program. Antibody-based assays, in particular ELISAs, have been shown to be useful to document C. trachomatis genital infections, but have not been explored extensively for ocular C. trachomatis infections. An antibody-based multiplex assay was used to test two C. trachomatis antigens, pgp3 and CT694, for detection of trachoma antibodies in bloodspots from Tanzanian children (n = 160) collected after multiple rounds of mass azithromycin treatment. Using samples from C. trachomatis-positive (by PCR) children from Tanzania (n = 11) and control sera from a non-endemic group of U.S. children (n = 122), IgG responses to both pgp3 and CT694 were determined to be 91% sensitive and 98% specific. Antibody responses of Tanzanian children were analyzed with regard to clinical trachoma, PCR positivity, and age. In general, children with more intense ocular pathology (TF/TI = 2 or most severe) had a higher median antibody response to pgp3 (p = 0.0041) and CT694 (p = 0.0282) than those with normal exams (TF/TI = 0). However, 44% of children with no ocular pathology tested positive for antibody, suggesting prior infection. The median titer of antibody responses for children less than three years of age was significantly lower than those of older children. (p<0.0001 for both antigens). The antibody-based multiplex assay is a sensitive and specific additional tool for evaluating trachoma transmission. The assay can also be expanded to include antigens representing different diseases, allowing for a robust assay for monitoring across NTD programs

A High Capacity Calcium Primary Cell Based on the Ca–S System

Conversion reaction cells afford the ability to explore new energy storage paradigms that transcend the dogma of small, low‐charge cations essential to intercalative processes. Here we report the use of earth‐abundant and green calcium and sulfur in unprecedented conversion reaction Ca–S primary cells. Using S‐infiltrated mesoporous carbon (abbreviated S@meso‐C) cathodes, we achieve discharge capacities as high as 600 mAh g^(−1) (S basis) within the geometry Ca|Ca(ClO_4)_2/CH_3CN|S@meso‐C, at a discharge rate of C/3.5. The electrolyte system in the Ca–S battery is of paramount importance as the solid electrolyte interface (SEI) formed on the Ca anode limits the capacity and stability of the cell. We determine that 0.5 M Ca(ClO_4)_2 in CH_3CN forms an SEI that advantageously breaks down under anodic bias to allow oxidation of the anode. This same SEI, however, exhibits high impedance which increases over time at open circuit limiting the shelf life of the cell

Bimodal Mesoporous Titanium Nitride/Carbon Microfibers as Efficient and Stable Electrocatalysts for Li–O_2 Batteries

The rechargeable Li–O_2 battery has been considered as a sustainable chemical power source for electric vehicles and grid energy storage systems due to the high theoretical specific energy (∼3500 Wh/kg). The practical performance of Li–O_2 batteries is, however, still far below expectations. This is mainly attributed to the (1) intrinsic sluggish reaction kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), (2) passivation of the electrodes by electrical isolation and pore blocking, and (3) chemical instability of the organic cell components, i.e., electrolyte, polymer binder, and carbon electrode, in the presence of O_2•– and Li_2O_2. It is crucial to develop highly porous, three-dimensional, conducting cathode catalyst/gas diffusion layer (GDL) architectures possessing superior catalytic activity and stability with respect to the ORR and the OER in order to address these issues. All of these requirements prompted us to examine the catalytic performance of porous framework metal nitride electrodes for Li–O_2 batteries

A High Capacity Calcium Primary Cell Based on the Ca–S System

Conversion reaction cells afford the ability to explore new energy storage paradigms that transcend the dogma of small, low‐charge cations essential to intercalative processes. Here we report the use of earth‐abundant and green calcium and sulfur in unprecedented conversion reaction Ca–S primary cells. Using S‐infiltrated mesoporous carbon (abbreviated S@meso‐C) cathodes, we achieve discharge capacities as high as 600 mAh g^(−1) (S basis) within the geometry Ca|Ca(ClO_4)_2/CH_3CN|S@meso‐C, at a discharge rate of C/3.5. The electrolyte system in the Ca–S battery is of paramount importance as the solid electrolyte interface (SEI) formed on the Ca anode limits the capacity and stability of the cell. We determine that 0.5 M Ca(ClO_4)_2 in CH_3CN forms an SEI that advantageously breaks down under anodic bias to allow oxidation of the anode. This same SEI, however, exhibits high impedance which increases over time at open circuit limiting the shelf life of the cell