Controlling pyridinic, pyrrolic, graphitic, and molecular nitrogen in multi-wall carbon nanotubes using precursors with different N/C ratios in aerosol assisted chemical vapor deposition

Nitrogen-containing multi-wall carbon nanotubes (N-MWCNTs) were synthesized using aerosol assisted chemical vapor deposition (CVD) techniques in conjunction with benzylamine:ferrocene or acetonitrile: ferrocene mixtures. Different amounts of toluene were added to these mixtures in order to change the N/C ratio of the feedstock. X-ray photoelectron and near-edge X-ray absorption fine structure spectroscopy detected pyridinic, pyrrolic, graphitic, and molecular nitrogen forms in the N-MWCNT samples. Analysis of the spectral data indicated that whilst the nature of the nitrogen-containing precursor has little effect on the concentrations of the different forms of nitrogen in N-MWCNTs, the N/C ratio in the feedstock appeared to be the determining factor. When the N/C ratio was lower than ca. 0.01, all four forms existed in equal concentrations, for N/C ratios above 0.01, graphitic and molecular nitrogen were dominant. Furthermore, higher concentrations of pyridinic nitrogen in the outer shells and N2 molecules in the core of the as-produced N-MWCNTs suggest that the precursors were decomposed into individual atoms, which interacted with the catalyst surface to form CN and NH species or in fact diffused through the bulk of the catalyst particles. These findings are important for a better understanding of possible growth mechanisms for heteroatom-containing carbon nanotubes (CNTs) and therefore paving the way for controlling the spatial distribution of foreign elements in the CNTs using CVD processes

Carbon States in Carbon-Encapsulated Nickel Nanoparticles Studied by Means of X-Ray Absorption, Emission, and Photoelectron Spectroscopies

Electronic structure of nickel nanoparticles encapsulated in carbon was characterized by photoelectron, X-ray absorption, and X-ray emission spectroscopies. Experimental spectra are compared with the density of states calculated in the frame of the density functional theory. The carbon shell of Ni nanoparticles has been found to be multilayer graphene with significant (about 6%) amount of Stone--Wales defects. Results of the experiments evidence protection of the metallic nanoparticles from the environmental degradation by providing a barrier against oxidation at least for two years. Exposure in air for 2 years leads to oxidation only of the carbon shell of Ni@C nanoparticles with coverage of functional groups.Comment: 16 pages, 6 figures, accepted in J. Phys. Chem.

Complex metabolic geroprophylaxis in older patients with polymorbidity

The purpose of the study is to detect geroprophylactic activity and its possible mechanisms under the conditions of Inosine + Nicotinamide + Riboflavin + Succinic acid (ATC Code: N07XX) use in older patients with polymorbidity.Цель исследования – обнаружить геропрофилактическую активность и возможные ее механизмы в условиях применения Инозина + Никотинамида + Рибофлавина + Янтарной кислоты; (Код АТХ: N07XX) у пациентов старшего поколения с полиморбидностью

Non-Standard Errors

In statistics, samples are drawn from a population in a data-generating process (DGP). Standard errors measure the uncertainty in estimates of population parameters. In science, evidence is generated to test hypotheses in an evidence-generating process (EGP). We claim that EGP variation across researchers adds uncertainty: Non-standard errors (NSEs). We study NSEs by letting 164 teams test the same hypotheses on the same data. NSEs turn out to be sizable, but smaller for better reproducible or higher rated research. Adding peer-review stages reduces NSEs. We further find that this type of uncertainty is underestimated by participants

Non-standard errors

In statistics, samples are drawn from a population in a data-generating process (DGP). Standard errors measure the uncertainty in estimates of population parameters. In science, evidence is generated to test hypotheses in an evidence generating process (EGP). We claim that EGP variation across researchers adds uncertainty: Non-standard errors (NSEs). We study NSEs by letting 164 teams test the same hypotheses on the same data. NSEs turn out to be sizable, but smaller for better reproducible or higher rated research. Adding peer-review stages reduces NSEs. We further find that this type of uncertainty is underestimated by participants