Dynamics of tachyon fields and inflation - comparison of analytical and numerical results with observation

The role tachyon fields may play in evolution of early universe is discussed in this paper. We consider the evolution of a flat and homogeneous universe governed by a tachyon scalar field with the DBI-type action and calculate the slow-roll parameters of inflation, scalar spectral index (n), and tensor-scalar ratio (r) for the given potentials. We pay special attention to the inverse power potential, first of all to V (x) ~ x−4, and compare the available results obtained by analytical and numerical methods with those obtained by observation. It is shown that the computed values of the observational parameters and the observed ones are in a good agreement for the high values of the constant X0. The possibility that influence of the radion field can extend a range of the acceptable values of the constant X0 to the string theory motivated sector of its values is briefly considered. [Projekat Ministarstva nauke Republike Srbije, br. 176021, br. 174020 i br. 43011

Effect of fermentation by Streptomyces sp. on antioxidant properties of spent coffee extracts

During espresso coffee preparation large amounts of spent coffee residues are produced and discarded daily as a part of the communal waste. However, there is a great potential in recycling this type of waste for extraction of natural antioxidants and manufacture of dietary supplements. The aim of this study was to investigate the effect of fermentation on the antioxidant properties of spent coffee extracts. Six series of spent espresso-type coffee samples were inoculated with selected natural strains of Streptomyces sp. The solid state-fermentation was carried out at 30°C five days. Aqueous extracts have been prepared and evaporated in the spray-dryer. The total polyphenol content was determined by Folin-Ciocalteu method and the antioxidant activity by two methods: inhibition DPPH (2,2-diphenyil-1-picrylhidrazyl) radicals and FRAP (Ferric Reducing Antioxidant Power). Inhibition of DPPH radicals was expressed as IC50 value. Results were compared to those of nonfermented control sample. Fermentation of spent coffee with these cultures have resulted in increased contents of polyphenols. Also, both methods have confirmed increased antioxidative activity in certain samples depending on the selected strains. It was therefore concluded that fermentation of spent coffee with Streptomyces sp. cultures have improved its antioxidative properties which presents a potential for its application in pharmaceutical and food industry

BEAMDB and MolD – databases for atomic and molecular collisional and radiative processes: Belgrade nodes of VAMDC

Abstract: We present two atomic and molecular (A&M) databases, MolD and BEAMDB, hosted by the SerVO – the Serbian virtual observatory (http://servo.aob.rs). These databases and web applications have been implemented in accordance to the standards developed by Virtual Atomic and Molecular Data Centre (VAMDC, http://www.vamdc.eu). The MolD database contains photo-dissociation cross-sections for individual rovibrational states of the diatomic molecular ions and rate coefficients for the atom-Rydberg atom chemi-ionisation and inverse electron-ion-atom chemi-recombination processes. The Belgrade electron/atom(molecule) database (BEAMDB) provides collisional data for electron interactions with atoms and molecules. Differential cross sections (DCS) are presented for both elastic and inelastic (excitation) cross sections in tabulated data tables. These DCS data are integrated over a full range of scattering angles in order to achieve integral, momentum transfer and viscosity cross sections as functions of impact electron energy. Beside these tables, energy loss spectra are presented in the graphical form