Synthesis of armchair graphene nanoribbons from the 10,10'-dibromo-9,9'-bianthracene molecules on Ag(111): the role of organometallic intermediates.

We investigate the bottom-up growth of N = 7 armchair graphene nanoribbons (7-AGNRs) from the 10,10'-dibromo-9,9'-bianthracene (DBBA) molecules on Ag(111) with the focus on the role of the organometallic (OM) intermediates. It is demonstrated that DBBA molecules on Ag(111) are partially debrominated at room temperature and lose all bromine atoms at elevated temperatures. Similar to DBBA on Cu(111), debrominated molecules form OM chains on Ag(111). Nevertheless, in contrast with the Cu(111) substrate, formation of polyanthracene chains from OM intermediates via an Ullmann-type reaction is feasible on Ag(111). Cleavage of C-Ag bonds occurs before the thermal threshold for the surface-catalyzed activation of C-H bonds on Ag(111) is reached, while on Cu(111) activation of C-H bonds occurs in parallel with the cleavage of the stronger C-Cu bonds. Consequently, while OM intermediates obstruct the Ullmann reaction between DBBA molecules on the Cu(111) substrate, they are required for the formation of polyanthracene chains on Ag(111). If the Ullmann-type reaction on Ag(111) is inhibited, heating of the OM chains produces nanographenes instead. Heating of the polyanthracene chains produces 7-AGNRs, while heating of nanographenes causes the formation of the disordered structures with the possible admixture of short GNRs.

Controlled assembly of graphene-capped nickel, cobalt and iron silicides.

The unique properties of graphene have raised high expectations regarding its application in carbon-based nanoscale devices that could complement or replace traditional silicon technology. This gave rise to the vast amount of researches on how to fabricate high-quality graphene and graphene nanocomposites that is currently going on. Here we show that graphene can be successfully integrated with the established metal-silicide technology. Starting from thin monocrystalline films of nickel, cobalt and iron, we were able to form metal silicides of high quality with a variety of stoichiometries under a Chemical Vapor Deposition grown graphene layer. These graphene-capped silicides are reliably protected against oxidation and can cover a wide range of electronic materials/device applications. Most importantly, the coupling between the graphene layer and the silicides is rather weak and the properties of quasi-freestanding graphene are widely preserved.

Controllable p-doping of graphene on Ir(111) by chlorination with FeCl3.

The in situ chlorination of graphene on Ir(111) has been achieved by depositing FeCl(3) followed by its thermal decomposition on the surface into FeCl(2) and Cl. This process is accompanied by an intercalation of Cl under graphene and formation of an epitaxial FeCl(2) film on top, which can be removed upon further annealing. A pronounced hole doping of graphene has been observed as a consequence of the annealing-assisted intercalation of Cl. This effect has been studied by a combination of core-level and angle-resolved photoelectron spectroscopies (CL PES and ARPES, respectively), near-edge x-ray absorption fine structure (NEXAFS) spectroscopy and low-energy electron diffraction (LEED). The ease of preparation, the remarkable reproducibility of the doping level and the reversibility of the doping upon annealing are the key factors making chlorination with FeCl(3) a promising route for tuning the electronic properties in graphene.

[Effect of gamma-plant preparation on production of TNF-alpha, IL-1 beta, and IL-6 in human peripheral blood mononuclear cells in vitro]. / Vliianie preparata gamma-plant na produktsiiu FNO-al'pha, IL-1 beta i IL-6 mononuklearami perifericheskoi krovi cheloveka in vitro.

The effect of a new medicine gamma-plant has antiinflammatory activity on human peripheral blood mononuclear cells obtained from healthy donors was studied. Its ability to influence TNF, IL-1 and IL-6 production via mononuclear cells was determined. Lymphokines spontaneous production and lymphokines productions by cells stimulated by LPS was studied. IL-1 content was defined with IL-1 sensitive cell line D10G4.1 while IL-6 content with IL-6 dependent heterohybridoma D6C8. TNF activity in supernatants was determined as lysis grade of TNF-sensitive cells of mouse fibrosarcoma L-929. It was shown that gamma-plant acted as stimulator when IL-1 production was low and as inhibitor when it was high. Stimulation of IL-6 production induced with LPS was achieved by low gamma-plant doses while for stimulation of spontaneous production higher doses were required. After nonstimulated LPS peripheral blood cells were treated with gamma-plant statistically sensible stimulated TNF production was observed apart from TNF synthesis level in a control group. The TNF production inhibition could never be demonstrated in subjects that showed in control cultures stimulated with LPS a level of TNF production lower than 100 pg/ml. In four of the five high TNF producers the cytokine release inhibition in LPS stimulated cultures has been observed. It is likely that the mild stimulation of the proinflammatory cytokine system has taken place. For example, simultaneously with stimulation of cytokine production the circulating IL-1 receptor antagonist and/or soluble TNF receptor may be induced.