Evaluating cardiac risks of TASER: An in-depth case study through probable current analysis.

This study investigates the cardiac safety concerns related to TASER discharges centering on a pivotal case that marked the first TASER-related fatality in South Korea. Employing Pratt et al.'s theoretical framework, the research evaluates the potential for ventricular fibrillation (VF) from these discharges. The methodology incorporated a high-resolution waveform analysis using sophisticated equipment and considered specific incident details, including dart impact locations verified through a forensic examination. A human body impedance of 500 Ω, chosen based on empirical studies and coupled with non-inductive resistance for high-voltage handling, was utilized in the model. By applying a heart-current factor from IEC 60479 standards, the study found a VF risk of up to 5% depending on the impact location and current pathways. In this specific case, although the calculated risk did not exceed critical thresholds, the VF risk was high enough to suggest that TASER discharges played a role in the fatal outcome. This study underscores the importance of dart impact location in TASER safety evaluations, contributing to a broader understanding of TASER cardiac risks and providing a basis to advocate for rigorous safety protocols.

Fenton-driven chemical regeneration of MTBE-spent granular activated carbon--a pilot study.

Three columns containing granular activated carbon (GAC) were placed on-line at a ground water pump and treat facility, saturated with methyl tert-butyl ether (MTBE), and regenerated with hydrogen peroxide (H2O2) under different chemical, physical, and operational conditions for 3 adsorption/oxidation cycles. Supplemental iron was immobilized in the GAC (≈6 g/kg) through the amendment of a ferrous iron solution. GAC regeneration occurred under ambient thermal conditions (21-27 °C), or enhanced thermal conditions (50 °C). Semi-continuous H2O2 loading resulted in saw tooth-like H2O2 concentrations, whereas continuous H2O2 loading resulted in sustained H2O2 levels and was more time efficient. Significant removal of MTBE was measured in all three columns using $(USD) 0.6 H2O2/lb GAC. Elevated temperature played a significant role in oxidative treatment, given the lower MTBE removal at ambient temperature (62-80%) relative to MTBE removal measured under thermally enhanced (78-95%), and thermally enhanced, acid pre-treated (92-97%) conditions. Greater MTBE removal was attributed to increased intraparticle MTBE desorption and diffusion and higher aqueous MTBE concentrations. No loss in the MTBE sorption capacity of the GAC was measured, and the reaction byproducts, tert-butyl alcohol and acetone were also degraded.

Persulfate oxidation of MTBE- and chloroform-spent granular activated carbon.

Activated persulfate (Na(2)S(2)O(8)) regeneration of methyl tert-butyl ether (MTBE) and chloroform-spent GAC was evaluated in this study. Thermal-activation of persulfate was effective and resulted in greater MTBE removal than either alkaline-activation or H(2)O(2)-persulfate binary mixtures. H(2)O(2) may serve multiple roles in oxidation mechanisms including Fenton-driven oxidation, and indirect activation of persulfate through thermal or ferrous iron activation mechanisms. More frequent, lower volume applications of persulfate solution (i.e., the persulfate loading rate), higher solid/solution ratio (g GAC mL(-1) solution), and higher persulfate concentration (mass loading) resulted in greater MTBE oxidation and removal. Chloroform oxidation was more effective in URV GAC compared to F400 GAC. This study provides baseline conditions that can be used to optimize pilot-scale persulfate-driven regeneration of contaminant-spent GAC.