Palladium monolayer-protected clusters (MPCs) coated with octylamines (C8NH(2)), hexanethiolates (C6S), and mixed monolayers of C8NH(2) and C6S exhibit significantly different reactivities with hydrogen gas, depending on the relative amounts of the two ligands coating the Pd nanoparticle surface, as determined by UV-vis spectroscopy of Pd MPCs in solution and electronic measurements of films of Pd MPCs as a function of exposure time to hydrogen. The average estimated composition of the ~3.0 nm diameter Pd MPCs was Pd(919)(C6S)(192) or Pd(919)(C8NH(2))(177-x)(C6S)(x), where x was varied to be 0, 3, 10, 16, 32, or 81 by the synthesis of pure C8NH(2) Pd MPCs and subsequent liquid-phase place exchange with a varied amount of C6SH. When x = 0-10, the Pd MPCs react strongly with H(2), leading to aggregated particles in solution and large irreversible changes in the morphology of films accompanied by an increase in film conductivity by 2-5 orders of magnitude. Pd(919)(C6S)(192) MPCs are stable against significant aggregation in solution and do not exhibit large film morphology changes, but they are also not highly reactive to H(2), as determined by minimal changes in the optical properties of solutions and the small, irreversible changes in the conductivity of films in the presence of H(2). Finally, when x is 32 and 81, the Pd MPCs are fairly stable, exhibit minimal aggregation or morphology changes, and readily react with H(2) based on the significant, reversible changes in film conductivity in the presence of H(2). Pd MPCs with mixed monolayers have the benefit of high H(2) reactivity while maintaining the structural stability necessary for sensing and catalysis applications.

Here, we describe the stability of solutions of various Pd and PdAg organic-protected nanoparticles (NPs) in the presence of H2 and their selectivity and reactivity as catalysts for hydrogenation or isomerization of allyl alcohol. Pd and Pd91Ag9 NPs stabilized with hexadecylamine (C16NH2) ligands are stable against H2-induced aggregation, whereas those stabilized with octylamines (C8NH2) and dodecylamines (C12NH2) precipitate within 1 h. The stability of C16NH2 Pd NPs is comparable to that of hexanethiolate (C6S)-protected Pd NPs and mixed monolayer C6S/C8NH2 (1/1) Pd NPs that were studied previously. The stability of C16NH2 Pd NPs decreases as the alkylamine/PdII ratio used in the synthesis decreases from 12:1 to 6:1 to 3:1. A bilayer or partial bilayer of C16NH2 ligands forms around the Pd core for ratios greater than 6:1, which explains the higher stability of these NPs against aggregation. The various Pd and PdAg NPs catalyzed the hydrogenation and isomerization of allyl alcohol in the presence of H2 with various selectivities and reactivities. C6S Pd NP catalysts are >95% selective toward the isomer; C8NH2/C6S Pd NPs are 60–75% selective toward the isomer, depending on the ligand ratio; and CnNH2-coated Pd NPs generally produce a 1:1 or 3:2 ratio of the hydrogenation/isomerization products, with a few exceptions. The catalytic turnover frequency (TOF) is low for C6S Pd NPs becaue of the strong thiolate–Pd bond. The TOF increases with increasing chain length in the order C16NH2 Pd > C12NH2 Pd > C8NH2 Pd and increases for Pd91Ag9 alloys compared with pure Pd. The mixed ligand C8NH2/C6S Pd NPs exhibit TOFs similar to pure C8NH2 Pd for low thiol content and similar to C6S Pd NPs for high thiol content. The 130/150 C8NH2/C6S Pd exhibits the optimal TOF for the mixed monolayer Pd NPs. C16NH2 Pd91Ag9 has the highest TOF of all the NPs studied due to the high stability afforded by the bilayer structure of the C16 chain and the high reactivity due to very little interference from the weak metal–amine interaction. Several of the Pd NPs that are stable in the presence of H2 are not stable during the catalysis reaction (H2 plus allyl alcohol), showing that the substrate also plays a role in NP stability.

A randomized double-blind clinical trial in 39 patients envenomed by Bothrops atrox in Antioquia and Chocó, Colombia, was performed to compare the efficacy and safety of 2 equine-derived antivenoms prepared at Instituto Clodomiro Picado, University of Costa Rica. Twenty patients received a monovalent anti-B. atrox antivenom (group A) and 19 patients were treated with a polyvalent (Crotalinae) antivenom (group B). Both antivenoms were equally efficient in the neutralization of the most relevant signs of envenoming (haemorrhage and blood clotting time alteration). Fourteen patients (36%) presented early adverse reactions to antivenoms and no significant difference between the 2 groups was observed. Urticaria (18%) was the most frequent early adverse reaction and there was no life-threatening anaphylactic reaction. Based on clinical criteria and serum venom levels, estimated by an enzyme immunoassay, 15 patients were classified into 2 groups: mild and moderate/severe envenoming. With the antivenom doses used in this study (3, 6 and 9 vials for mild, moderate and severe envenoming, respectively), both antivenoms were equally efficient in clearing serum venom levels within the first hour of treatment, and the levels remained below the lower limit of venom detection for 24 h. Antivenom concentration in serum remained high for up to 24 h after antivenom infusion, suggesting that an excess of antibody in relation to circulating antigen had been administered.

Here, we developed a simple method for obtaining a heterojunction composed of graphene (G) and surfactant-coated Au nanoparticles (NPs) to measure film conductivity and surface enhanced Raman scattering (SERS). Monolayer G is obtained by chemical vapor deposition (CVD) and transferred via poly(methyl methacrylate) (PMMA) to microfabricated Au electrodes, glass, and silicon. Post-synthesis treatments of G with PMMA and ozone (O3) showed 1 and 6 orders of magnitude decrease in film conductivity, respectively. The heterojunction formation with Au NPs had no major effect on G conductivity. In this work is demonstrated that G quenches more than 90% of the combined photoluminescence and fluorescence of Au NPs and Rhodamine B (RhB), respectively. Signal quenching permitted quantitative analysis of SERS of RhB on various substrates including as-transferred graphene, oxidized graphene (OG), and the heterojunction. While G is mainly responsible for quenching photoluminescence and fluorescence, ∼3 orders of magnitude increase SERS activity for RhB was accomplished by the heterojunction. Finally, we wanted to correlate changes in film current during UV light sensing experiments. We found striking differences in the sensing profiles at different UV energies.

Aprepitant allows for better control of CINV in HEC regimens with CDDP, and this control is accurately perceived by physicians and nurses. However, physicians and nurses overestimate the control of delayed CINV after HEC regimens without CDDP and after MEC. CINV is still an important target for improved therapeutic intervention and the healthcare providers must be aware of its actual incidence.

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