RESUMEN
This research investigated the mechanism of perchlorate (ClO(4)(-)) formation from chlorate (ClO(3)(-)) on boron-doped diamond (BDD) film anodes by use of a rotating disk electrode reactor. Rates of ClO(4)(-) formation were determined as functions of the electrode potential (2.29-2.70 V/standard hydrogen electrode, SHE) and temperature (10-40 °C). At all applied potentials and a ClO(3)(-) concentration of 1 mM, ClO(4)(-) production rates were zeroth-order with respect to ClO(4)(-) concentration. Experimental and density functional theory (DFT) results indicate that ClO(3)(-) oxidation proceeds via a combination of direct electron transfer and hydroxyl radical oxidation with a measured apparent activation energy of 6.9 ± 1.8 kJ·mol(-1) at a potential of 2.60 V/SHE. DFT simulations indicate that the ClO(4)(-) formation mechanism involves direct oxidation of ClO(3)(-) at the BDD surface to form ClO(3)(â¢), which becomes activationless at potentials > 0.76 V/SHE. Perchloric acid is then formed via the activationless homogeneous reaction between ClO(3)(â¢) and OH(â¢) in the diffuse layer next to the BDD surface. DFT simulations also indicate that the reduction of ClO(3)(â¢) can occur at radical sites on the BDD surface to form ClO(3)(-) and ClO(2), which limits the overall rate of ClO(4)(-) formation.
Asunto(s)
Boro/química , Diamante/química , Percloratos/síntesis química , Contaminantes Químicos del Agua/síntesis química , Electrodos , Restauración y Remediación Ambiental/métodos , Oxidación-Reducción , Percloratos/análisis , Contaminantes Químicos del Agua/análisisRESUMEN
Ultrasound (US) is rapid, non-invasive, simple, effective, and presents a viable and practical alternative to conventional radiography (CR) for the Special Forces Medical Sergeant (18D), particularly in the deployed setting. The authors present four cases that illustrate the ability of US used by the 18D to detect fractures in a combat theater. This success invites a debate as to what extent the Special Operations Forces (SOF) community should field US as it demonstrates a number of distinct advantages over the existing gold standard of portable conventional radiography.
Asunto(s)
Fracturas Óseas/diagnóstico por imagen , Personal Militar , Sistemas de Atención de Punto , Adulto , Preescolar , Diseño de Equipo , Fracturas Óseas/etiología , Humanos , Masculino , Radiografía , Ultrasonografía , Adulto JovenRESUMEN
Over the past few decades, ultrasound has evolved from a radiology and subspecialist-centric instrument, to a common tool for bedside testing in a variety of specialties. The SOF community is now recognizing the relevancy of training medics to employ this technology for multiple clinical indications in the austere operating environment. In the Fall 2008 issue of Journal of Special Operations Medicine two of the authors described the concept of training SOF medics to employ portable ultrasound as a diagnostic aid. After over two years of concerted effort, the authors trained 29 out of 40 medics of a Special Forces battalion. Retrospective analysis of the quality assurance data for ultrasound studies conducted placed the 109 studies into six categories, allowing inference of trends in clinical indication for ultrasound exams as determined by the SOF medic-ultrasonographer. The resulting distribution suggests that indications for fractures and superficial applications are as prevalent as those for focused abdominal sonography in trauma (FAST) and pneumothorax exams. This analysis focuses on Special Operator Level Clinical Ultrasound (SOLCUS), an ultrasound training curriculum specifically for SOF medics, and helps appropriately prioritize its objectives. Despite the success of this experience, there are several issues requiring resolution before being able to integrate ultrasound training and fielding into the SOF medical armamentarium.
Asunto(s)
Medicina de Emergencia/educación , Medicina Militar/educación , Sistemas de Atención de Punto , Heridas y Lesiones/diagnóstico por imagen , Campaña Afgana 2001- , Competencia Clínica , Curriculum , Medicina de Emergencia/instrumentación , Humanos , Medicina Militar/instrumentación , Evaluación de Programas y Proyectos de Salud , Estudios Retrospectivos , Ultrasonografía , Estados Unidos , Heridas y Lesiones/etiologíaRESUMEN
Tyrrellite, a naturally occurring Co-Ni-Cu selenide, has been studied by single-crystal X-ray diffraction. It possesses the normal spinel-type structure, with Cu occupying the tetrahedral site and (Co+Ni) the octahedral site. The average Cu-Se distance of 2.3688 (2) A is close to that of 2.3703 (8) A in CuCr(2)Se(4), whereas the average (Co+Ni)-Se distance of 2.3840 (1) A appears to be slightly shorter than most octahedral Co-Se or Ni-Se distances ( approximately 2.40-2.50 A) in other selenides. The refined structure provides a basis for a redefinition of the ideal chemical formula of tyrrellite, which should be Cu(Co,Ni)(2)Se(4), rather than the previously suggested (Cu,Co,Ni)(3)Se(4).