RESUMEN
Controlling the surface structure of Pt nanocrystals (NCs), especially creating high-index facets with abundant active step sites, is an effective approach to enhance catalytic performances. However, the available high-index faceted Pt NCs have large particle sizes, which severely impedes their practical applications. In this study, we reported a new electrochemically seed-mediated method, by which sub-10 nm tetrahexahedral Pt NCs (THH Pt NCs) enclosed with {210} high-index facets supported on graphene were synthesized. Pt nanoparticles of â¼3 nm in size as high-density crystal seeds play a key role in the small-sized control. The obtained THH Pt NCs exhibited a higher mass activity than commercial Pt/C catalyst for ethanol electrooxidation. We further demonstrated that this method is also valid for reshaping commercial Pt/C, to create high-index facets on surfaces and thus to improve both mass activity and stability.
RESUMEN
Shape transformation of Pt nanocrystals from a {730}-bounded tetrahexahedron into a {310}-bounded truncated ditetragonal prism was achieved using the electrochemical square-wave potential method. The transformation process and mechanism were revealed. This study provides new insight into the nanocrystal growth habit.
RESUMEN
Cyclin-dependent kinase 1 (CDK1) is the only necessary CDK in the cell proliferation process and a new target in the research and development of anti-cancer drugs. 8-Hydroxypiperidinemethyl-baicalein (BA-j) is a Mannich base derivative of baicalein (BA) isolated from Scutellaria baicalensis, as a novel selective CDK1 inhibitor. 12 metabolites of BA-j in the monkey urine were identified by LC-MS-MS and (1)H NMR. The major metabolic pathways of BA-j, by capturing oxygen free radicals ((.)O2(-)) and releasing peroxides (H2O2), are degraded into active intermediate metabolite dihydroflavonol, then into main metabolite M179 by Shiff reaction, second metabolite M264 by sulfation, trace amount of metabolite M559 by glucuronidation UGT1A9, and without metabolism by CYP3A4. The metabolic process of BA-j by regulating intracellular reactive oxygen species (ROS) was related with BA-j selectively inducing apoptosis in cancer cells. Pharmacokinetics of 10mg/kg oral BA-j in monkey by HPLC-UV was best fitted to a two-compartment open model, with t1/2(ß) of 4.2h, Cmax 25.4µM at 2h, and Vd 12.6L, meaning the drug distributing widely in body fluids with no special selectivity to certain tissues, and being able to permeate through the blood-brain barrier. The protein binding rate of BA-j was 91.8%. BA-j has excellent druggability for oral administration or injection, and it may be developed into a novel anti-cancer drug as a selective CDK1 inhibitor.