Ag and N acceptors in ZnO: ab initio study of acceptor pairing, doping efficiency, and the role of hydrogen

Efficiency of ZnO doping with Ag and N shallow acceptors, which substitute respectively cations and anions, was investigated. First principles calculations indicate a strong tendency towards formation of nearest neighbor Ag-N pairs and N-Ag-N triangles. Binding of acceptors stems from the formation of quasi-molecular bonds between dopants, and has a universal character in semiconductors. The pairing increases energy levels of impurities, and thus lowers doping efficiency. In the presence of donors, pairing is weaker or even forbidden. However, hydrogen has a tendency to form clusters with Ag and N, which favors the Ag-N aggregation and lowers the acceptor levels of such complexes.Comment: 10 pages, 4 figure

Supernatants derived from chemotherapy-treated cancer cell lines can modify angiogenesis

BACKGROUND: There is evidence that tumours produce substances such as cytokines and microvesicular bodies bearing bioactive molecules, which support the carcinogenic process. Furthermore, chemotherapy has also been shown to modify these exudates and in doing so, neutralise their tumourigenic influence. METHODS: In the current study, we have investigated the effect of chemotherapy agents on modifying the cytokine profile and microvesicular cargo of supernatants derived from cancer cell lines. In addition, we have explored the effect of these tumour-derived supernatants on angiogenesis, and how chemotherapy can alter the supernatants rendering them less pro-angiogenic. RESULTS: Herein, we show that supernatants contain a rich cocktail of cytokines, a number of which are potent modulators of angiogenesis. They also contain microvesicular bodies containing RNA transcripts that code for proteins involved in transcription, immune modulation and angiogenesis. These supernatants altered intracellular signalling molecules in endothelial cells and significantly enhanced their tubulogenic character; however, this was severely compromised when supernatants from tumours treated with chemotherapy was used instead. CONCLUSION: This study suggests tumour exudates and bioactive material from tumours can influence cellular functions, and that treatment with some chemotherapy can serve to negate these pro-tumourigenic processes

Kaon physics with the KLOE detector

In this paper we discuss the recent finalized analyses by the KLOE experiment at DA$\Phi$NE: the CPT and Lorentz invariance test with entangled $K^0 \bar{K}^0$ pairs, and the precision measurement of the branching fraction of the decay ${ K^+} \rightarrow \pi^+\pi^-\pi^+(\gamma)$. We also present the status of an ongoing analysis aiming to precisely measure the $K^{\pm}$ mass

Unexpected Crossover in the kinetics of mutarotation in the supercooled region : the role of H-bonds

Intra- and intermolecular studies on the molten L-sorbose have been carried out at variable temperature conditions to determine the crosover temperature (Tc). In addition, isothermal time-dependent FTIR and Raman measurements were performed to probe the pace of mutarotation and activation energy of this reaction in the studied saccharide, which varied from 53–62 kJ/mol up to 177–192 kJ/mol below and above Tc, respectively. To explain the change in activation barrier for the mutarotation a complementary analysis using difference FTIR spectra collected around Tc = 365 K in the hydroxyl region has been done. It was found that the alteration of kinetic parameters and molecular dynamics around Tc are strictly related to the variation in the strength of H-bonds which above Tc are significantly weaken, increasing the freedom of rotation of functional groups and movement of individual molecules. That phenomenon most likely affects the proton transfer, underlying molecular mechanism of mutarotation, which may lead to the significant increase in activation barrier. The new insight into a molecular aspect of the mutarotation around Tc has created an opportunity to better understanding the relationship between physics of condensed matter and the potential role of H-bonds dynamics on the progress of the chemical reaction in highly viscous systems

Infrared spectra of some fructans

Abstract. The FT-IR spectra of fructan -inulin (RAFTILINE), widely applied in the food industry and crystalline fructose as the main component of fructans, were studied. Special interest was to study the spectra of the levan precipitate and fructan syrup -produced by Zymomonas mobilis during the fermentation on sucrose-based medium. It was shown that levan precipitate and fructose syrup does not contain lipids and nucleic acids. Levan precipitate consists of ∼93% of fructose and admixture of glucose, mannan and enzyme -levansucrase. Fructan polymer inulin consists principally of linear chains of fructosyl units linked by a β(2-1) bonds ended by a glycosyl unit. The links between the molecules are of a very special type: the β(2-1) form (2