Intermetallic Pd-Y nanoparticles/N-doped carbon nanotubes as multi-active catalysts for oxygen reduction reaction, ethanol oxidation reaction, and zinc-air batteries.

Intermetallic nanomaterials are unique in terms of their band gap, atomic-level arrangement, and well-defined stoichiometry, which allows them to exhibit significantly enhanced catalytic performance in electrochemical applications. However, the preparation of durable intermetallic catalysts with a lower content of platinum group metals is challenging, while the lack of control over the loss of active components limits their long-term application due to weak interaction between the support and the nanostructure. Here, we have designed the intermetallic alloyed nanoparticles (NPs) of PdY on N-doped carbon nanotubes (PdY/NCNTs) as a multifunctional catalyst for the oxygen reduction reaction (ORR), the ethanol oxidation reaction (EOR), and zinc-air batteries (ZABs). The strong adhesion through nitrogen ensures the anchoring of alloyed PdY NPs on the NCNTs, which restrains atomic migration and sintering during their conversion to intermetallic phases. This study confirms that there is negligible active site leaching owing to the strong and multiple dative bonds between the NCNTs and PdY NPs. Therefore, this catalyst exhibits remarkable catalytic activity, resulting in a mass activity of 1317 and 2902 mA mgPd-1 at jk and jf for the ORR and the EOR, respectively, and remains stable for a longer period. In addition, the PdY/NCNT-containing air cathode-fabricated ZAB achieved a higher power density (0.236 W cm-2) compared to the benchmark Pt/C.

Characteristic electronic perturbation by asymmetric arrangements of p-aminophenyl substituents in free-base porphyrins.

We have investigated the perturbed electronic properties of meso-substituted free-base porphyrins with symmetric and asymmetric arrangements of substituents using time-resolved spectroscopic measurements and theoretical calculations. The extent of electronic perturbation by substituents in meso-substituted porphyrins is mainly affected by the isoenergetic condition of frontier MOs of porphine and substituent units, nonorthogonal geometry, and geometrical arrangement of substituents. By using the asymmetric arrangements of p-aminophenyl and pentafluorophenyl substituents, we can induce the electron-rich condition on the porphine unit and the intramolecular charge transfer character in the excited state. On the basis of this work, we can gain further insight into the energetic and geometric factors of substituents, the interaction between porphine and substituent units, and the perturbed photophysical and electronic properties by substituents, which provides a firm basis for further understanding of the catalytic activities or photophysical properties of porphyrins in porphyrin-based molecular catalysts and electronics.

Comparison of intravitreal bevacizumab alone or combined with triamcinolone versus triamcinolone in diabetic macular edema: a randomized clinical trial.

PURPOSE: To compare the effect of an intravitreal injection of bevacizumab alone (IVB) or combined with triamcinolone (IVB/IVT) versus triamcinolone (IVT) in patients with diabetic macular edema (DME). METHODS: In this randomized three-arm clinical trial, eligible eyes were assigned randomly to one of the three study arms: the IVB group, 2 injections of 1.25 mg of bevacizumab with 6-week intervals; the IVB/IVT group, 1.25 mg of IVB with 2 mg of IVT, and the IVT group, 2 mg of IVT. The clinical course of best-corrected visual acuity and central macular thickness by optical coherence tomography was monitored for up to 12 months after the initial injection. RESULTS: One hundred eleven eyes of 105 patients with DME completed 12 months of follow-up. The IVB/IVT group and the IVT group showed better visual acuity and reduced central macular thickness at 6 weeks and 3 months, compared with the IVB group (p = 0.041, p = 0.02 at 6 weeks; p = 0.045, p = 0.043 at 3 months, respectively). However, no significant difference in visual acuity and central macular thickness was observed between the three groups at 12 months (p = 0.088, p = 0.132, respectively). The frequency of retreatment was lower in the IVB/IVT and IVT groups during the 12-month period (p < 0.001). No significant differences in visual acuity or central macular thickness were observed between the IVB/IVT and IVT groups during the follow-up. CONCLUSION: IVB/IVT and IVT showed more pronounced effects during the earlier postinjection period. However, levels of visual acuity or central macular thickness at 12 months were comparable in the three study groups. No beneficial effect of the combination injection was observed.

Electrocatalytic oxidation of formic acid by poly(diallyldimethylammonium chloride) and Pt/Pd-functionalized carbon nanotubes mixtures.

Improving the catalytic activity of the anode catalyst is an important task in the direct formic acid fuel cell (DFAFC). In this study, the catalysts were prepared by dispersing either platinum or palladium metal on the surface of thiolated multi-walled carbon nanotubes (t-MWCNTs), denoted as t-MWCNT-Pt and t-MWCNT-Pd, respectively. These modified t-MWCNT and poly(diallyldimethylammonium chloride) (PDDA) were ultrasonically mixed and loading on a glassy carbon electrode (GCE) for formic acid (FA) oxidation and the catalytic activities were then investigated by using cyclic voltammetry (CV) and chronoamperometry (CA) methods. The as-formed catalysts were characterized by several methods. To optimize the catalytic performance, we investigated the catalysts separately and together (in different ratios) for FA oxidation. The PDDA mixed catalyst demonstrated a slightly better performance. These results indicated that the PDDA/(t-MWCNT-Pt + t-MWCNT-Pd) catalyst exhibited better activity than that of the corresponding other catalysts.

A lead(II)-selective PVC membrane based on a Schiff base complex of N,N'-bis(salicylidene)-2,6-pyridinediamine.

PVC membrane electrodes for lead ion based on N,N'-bis(salicylidene)-2,6-pyridinediamine as membrane carrier were prepared. Among their membranes, a membrane electrode (m-3) containing o-NPOE as a plasticizer and 50mol% additive displays an excellent Nernstian response (29.4mV/decade) and the limit of detection of -loga (M) = 6.04 to Pb(2+) in Pb(NO(3))(2) solutions at room temperature. It has a rapid response time within 10s over the entire concentration range. The proposed electrode revealed good selectivity and response for Pb(2+) over a wide variety of other metal ions in a pH 5.0 buffer solutions, and good reproducibility of base line in subsequent measurements.

Nitrate-selective electrodes based on meso-tetrakis[(2-arylphenylurea)-phenyl]porphyrins as neutral lipophilic ionophores.

Polymeric-membrane electrodes for NO(3)(-) anion based on (alpha,alpha,alpha,alpha)-5,10,15,20-tetrakis [2-(4-methylphenylurea)phenyl]porphyrin I and similar urea-functionalized porphyrins II-IV as neutral ionophores were prepared. The effects of polymeric-membrane composition and test solution pH were tested. The electrodes revealed good selectivity coefficients for NO(3)(-) over a wide variety of other anions, and the values of eight anions were measured. Of the various electrodes prepared, the electrode based on urea-functionalized porphyrin I exhibits a linear stable response over a wide concentration range (1.0x10(-5) to 1.0x10(-1)) with a slope of -57.4mV per decade, a detection limit of log[NO(3)(-)]=-5.72, and a selectivity coefficient for nitrate against perchlorate anion (log K (NO (3)(-),j)(pot )=-1.81 ).