Comparison of Carbon Supports in Anion Exchange Membrane Fuel Cells

Anion exchange membrane fuel cells (AEMFCs) are attractive alternatives to proton exchange membrane fuel cells due to their ability to employ nonprecious metals as catalysts, reducing the cost of AEMFC devices. This paper presents an experimental exploration of the carbon support material effects on AEMFC performance. The silver (Ag) nanoparticles supported on three types of carbon materials including acetylene carbon (AC), carbon black (CB), and multiwalled carbon nanotube (MWCNT)—Ag/AC, Ag/CB, and Ag/MWCNT, respectively—were prepared using the wet impregnation method. The silver loading in the catalysts was designed as 60 wt.% during the synthesizing process, which was examined using thermogravimetric analysis. The elemental composition of the prepared Ag/AC, Ag/CB, and Ag/MWCNT catalysts was confirmed using X-ray diffraction analysis. The nanoparticle size of Ag attached on carbon particles or carbon nanotubes, as observed by scanning electron microscopy (SEM), was around 50 nm. For the performance tests of a single AEMFC, the obtained results indicate that the maximum power density using Ag/MWCNT as the cathode catalyst (356.5 mW·cm⁻²) was higher than that using Ag/AC (329.3 mW·cm⁻²) and Ag/CB (256.6 mW·cm⁻²). The better cell performance obtained using a MWCNT support can be ascribed to the higher electrical conductivity and the larger electrochemical active surface area calculated from cyclic voltammetry measurements.     

Comparison of the Diamond-Forrester method and Duke Clinical Score to predict obstructive coronary artery disease by computed tomographic angiography

We sought to evaluate the ability of the Diamond and Forrester method (DFM) and the Duke Clinical Score (DCS) to predict obstructive coronary artery disease (CAD) on coronary computed tomographic angiography (CCTA) and the effect of these different risk scores on the appropriateness level using the 2010 Appropriate Use Criteria. Consecutive symptomatic patients who underwent CCTA for evaluation of CAD (n = 114) were classified as having a low, intermediate, or high pretest probability using the DFM and DCS. Using the Appropriate Use Criteria, the indications for CCTA were classified according to the pretest probability and previous testing. The CCTA results were classified as revealing obstructive (≥70% stenosis), nonobstructive (<70%), or no CAD. When the patients' risk was classified using the DFM, 18% were low, 65% intermediate, and 17% high risk. When using the DCS, 53% of patients had a reclassification of their risk, most of whom changed from intermediate to either low or high risk (50% low, 19% intermediate, 35% high risk). The net reclassification improvement for the prediction of obstructive CAD was 51% (p = 0.01). Of the 37 patients who were reclassified as low risk, 36 (97%) lacked obstructive CAD. Appropriateness for CCTA was reclassified for 13% of patients when using the DCS instead of the DFM, and the number of appropriate examinations was significantly fewer (68% vs 55%, p <0.001). In conclusion, reclassification of risk using the DCS instead of the DFM resulted in improved prediction of obstructive CAD on CCTA, especially in low-risk patients. More patients were categorized as having a high pretest probability of CAD, resulting in reclassification of their examination indications as uncertain or inappropriate. These results identify the need for improved pretest risk scores for noninvasive tests such as CCTA and suggest that the method of risk assessment could have important implications for patient selection and quality assurance programs.     

AbobotulinumtoxinA (Dysport) dosing in cervical dystonia: an exploratory analysis of two large open-label extension studies

Treatment with botulinum toxin-A is recommended as first-line treatment for cervical dystonia (CD). In clinical practice many factors appear to influence dose adjustment and the retreatment regimen; however, there is little information available in the literature regarding the evolution of dosing over treatment cycles. We report on two similarly designed, long-term, multicenter, open-label extension studies of Dysport for the treatment of CD, which followed 500 U fixed-dose placebo-controlled trials. Both studies specified a fixed 500 U dose for the first open-label treatment cycle, with dose adjustment in subsequent treatment cycles according to the clinical response. These analyses include 218 patients who entered the two studies; doses in the subsequent treatment cycles ranged between 250 and 1,000 U. During open-label treatment, all treatment cycles resulted in improvements in mean Toronto Western Spasmodic Torticollis Rating Scale (TWSTRS) total scores. However, increasing the dose of Dysport above the initial 500 U dose was not observed to result in an incremental improvement in response as measured by the TWSTRS. No individual patient characteristic was found to reliably predict the use of higher doses at each treatment cycle. Dysport was generally well tolerated with no major differences in the incidence of adverse events (AEs) observed with different doses. Dysphagia was considered an AE of special interest and dysphagia data from the open-label studies were combined with two Phase II studies. Analysis of this enhanced database indicates that unilateral injections of >150 U into the sternocleidomastoid muscle is associated with a higher dysphagia risk. Thus, limiting the dose in the sternocleidomastoid may help reduce the incidence of dysphagia.