Electrocatalytic Activity of Pd_{20–<i>x</i>}Ag_<i>x</i> Nanoparticles Embedded in Carbon Nanotubes for Methanol Oxidation in Alkaline Media

Low Pd content and highly active bimetallic PdAg electrocatalytic nanoparticles supported on functionalized multiwalled carbon nanotubes (CNT) have been developed for the electrochemical methanol oxidation reaction (MOR). The polyol synthesis procedure is used to substitute Ag into Pd particles in a Pd/CNT matrix. The Pd_{20–<i>x</i>}Ag_<i>x</i>/CNT samples (<i>x</i> wt % = 0, 5, 10, and 15) are characterized by XRD, XPS, Raman spectroscopy, and microscopy methods. The electrocatalytic activities and stabilities of Pd_{20–<i>x</i>}Ag_<i>x</i>/CNT catalysts were examined by cyclic voltammetry (CV), chronoamperometry (CA), and chronopotentiometry (CP) measurements for electrochemical oxidation of methanol in alkaline media. The Pd_{20–<i>x</i>}Ag_<i>x</i>/CNT with <i>x</i> = 10 wt % is found to be a semialloyed sample and shows the best catalytic activity (731 mA mg^–1) compared to the Pd/CNT catalyst (408 mA mg^–1) and other samples. This semialloyed sample also shows long stability and high resistance toward CO poisoning. The semialloyed Pd₁₀Ag₁₀ particles with optimized metal ratio on CNT matrix would be a promising catalyst material for direct methanol fuel cell applications

<i>Leptospira</i> C_T values in the Lepto-MD assay for patients with recorded day of disease information.

<p><i>Leptospira</i> C_T values in the Lepto-MD assay for patients with recorded day of disease information.</p

Leptospirosis cases and recorded rainfall in Rio de Janeiro by study month.

<p>(A) Leptospirosis cases diagnosed by RT-PCR (blue), MAT (maroon), or both (purple) are displayed by study month. MAT results are shown for all samples from 2008. (B) Rainfall for 2008 (black circles and line) and the average rainfall for the years 2003–2013 (red triangles and line).</p

Patient characteristics associated with 478 samples that tested positive and negative for <i>Leptospira</i>.

<p>Abbreviations: SD, standard deviation</p><p>¹ 65 samples tested positive for <i>Leptospira</i> in the Lepto-MD assay and/or by MAT; 3 samples tested positive by both methods.</p><p>Patient characteristics associated with 478 samples that tested positive and negative for <i>Leptospira</i>.</p

Reported clinical data for 65 samples from patients with suspected leptospirosis.

1<p>Includes nausea, vomiting, abdominal pain, diarrhea, anorexia, and hemorrhage.</p>2<p>Includes cough, shortness of breath, and hemoptysis.</p><p>Reported clinical data for 65 samples from patients with suspected leptospirosis.</p

Pairwise comparisons of <i>Leptospira</i> PCR diagnostics.

<p>Comparison of the pathogenic <i>rt</i>PCR with the UFI assay, reference 16S rtPCR, conventional PCRs for <i>flaB/lipL41</i>, and a composite reference that takes into account <i>flaB/lipL41</i> and the reference 16S rtPCR. Samples that tested positive by at least one of these assays were considered positive, while those that tested negative by both assays were considered negative for this composite reference. Samples that tested negative in the pathogenic rtPCR had C_T values of 34.77, 35.26, and 36.11 in the UFI assay.</p><p>Pairwise comparisons of <i>Leptospira</i> PCR diagnostics.</p

Reference <i>Leptospira</i> isolates tested with the pathogenic and reference 16S rtPCRs.

<p>Reference <i>Leptospira</i> isolates tested with the pathogenic and reference 16S rtPCRs.</p

Amplicon sequencing results and C_T values for select clinical samples.

1<p>Given the highly conserved nature of this region, final species determinations cannot be made from amplicon sequences.</p><p>Amplicon sequencing results and C_T values for select clinical samples.</p

The pathogenic rtPCR does not amplify DNA from cultured <i>L. biflexa</i> isolates.

<p>Amplification curves for cultured isolates of <i>L. interrogans</i> (solid diamonds) and <i>L. biflexa</i> (open circles) in the (A) pathogenic rtPCR and (B) UFI assay. Results are displayed for two isolates of each species. The threshold for positivity is set at 0.05 normalized fluorescence units for both assays (dotted red line).</p

BLAST alignment for the targeted 16S rRNA gene consensus sequences from pathogenic (top) and non-pathogenic (bottom) strains of <i>Leptospira</i>.

<p>The forward primer sequence and the complement of the reverse primer sequence used in the pathogenic rtPCR and UFI assay are labeled, as are the general (UFI assay) and pathogenic probe sequences.</p