On the Electrostatic Calculation of the ESCA Chemical Shifts

The electrostatic formula for the calculation of the ESCA chemical shifts is developed within the framework of the INDO approximation and by using Taylor expansion of the 1/r operator. The INDO wavefunctions were employed for the calculation of the ls electron binding energy changes in some characteristic organic molecules. It was shown that the electrostatic formula based on the point charge approximation workls quite well and that the inclusion of the polarized charge cloud does not improve the results to any significant extent

On the Electrostatic Calculation of the ESCA Chemical Shifts

The electrostatic formula for the calculation of the ESCA chemical shifts is developed within the framework of the INDO approximation and by using Taylor expansion of the 1/r operator. The INDO wavefunctions were employed for the calculation of the ls electron binding energy changes in some characteristic organic molecules. It was shown that the electrostatic formula based on the point charge approximation workls quite well and that the inclusion of the polarized charge cloud does not improve the results to any significant extent

A two-stage metal valorisation process from electric arc furnace dust (EAFD)

This paper demonstrates possibility of separate zinc and lead recovery from coal composite pellets, composed of EAFD with other synergetic iron-bearing wastes and by-products (mill scale, pyrite-cinder, magnetite concentrate), through a two-stage process. The results show that in the first, low temp erature stage performed in electro-resistant furnace, removal of lead is enabled due to presence of chlorides in the system. In the second stage, performed at higher temperatures in Direct Current (DC) plasma furnace, valorisation of zinc is conducted. Using this process, several final products were obtained, including a higher purity zinc oxide, which, by its properties, corresponds washed Waelz oxide

Electrochemical Characterization of Bronze Exposed to Outdoor Atmosphere

The aim of this work was to examine corrosion behaviour of bare and artificial patinated bronzes during exposure to urban outdoor atmosphere. Studies were conducted on copper and two different bronzes in order to evaluate the influence of substrate composition on patina composition and electrochemical behaviour. Additionally, two different patination methods were compared. Corrosion behaviour was examined using electrochemical impedance spectroscopy with gel-electrolyte electrochemical cell. The composition of patina was determined by ATR-FTIR spectroscopy. The obtained results showed that all studied artificial patinas initially decrease the corrosion resistance of copper and bronzes but in time their corrosion resistance improves, and even for certain combinations, artificial patina-bronze corrosion resistance is higher than that of naturally patinated bronze. This work is licensed under a Creative Commons Attribution 4.0 International License

Učinci hiperbaričnog kisika na vidne funkcije u bolesnika s ishemičnom optičkom neuropatijom

The effects of hyperbaric oxygen therapy were studied in nine patients with non-arteritic anterior ischaemic optic neuropathy, who had been unsatisfactorily treated with corticosteroids. In four patients with signs of optic disc atrophy there was no improvement of visual functions after hyperbaric oxygen treatment, whereas in the other five patients, who had no signs of optic disc atrophy, visual acuity and visual field improved. The achieved improvements were maintained al a control examination six months later. Results suggest that hyperbaric oxygen might be a new remedy for the selected cases of non-arteritic ischaemic optic neuropathy and call for a controlled clinical study aiming to acurately assess its efficacy.Ispitivani su učinci tretmana hiperbaričnim kisikom u devet bolesnika s nearteritičinim oblikom prednje ishemične optikoneuropatije, koji su prethodno liječeni kortikosteroidima bez uspjeha. U četiri bolesnika sa znakovima atrofije optičkog diska, nakon tretmana hiperbaričnim kisikom, nije nađeno nikakvo poboljšanje vidnih funkcija, dok je u ostalih pet, bez znakova atrofije optičkog diska, ustanovljeno poboljšanje oštrine vida i vidnog polja. Ova poboljšanja nađena su i na kontrolnom pregledu nakon šest mjeseci. Rezultati ispitivanja sugeriraju hiperbaričnu oksigenaciju kao moguć način liječenja selekcioniranih slučajeva nearteritičnog oblika ishemične optikoneuropatije, kao i kontrolirani klinički pokus, radi egzaktnijeg utvrđivanja efikasnosti hiperbarične oksigenacije u ovih bolesnika

Spectral Optical Monitoring of the Narrow Line Seyfert 1 galaxy Ark 564

We present the results of a long-term (1999--2010) spectral optical monitoring campaign of the active galactic nucleus (AGN) Ark 564, which shows a strong Fe II line emission in the optical. This AGN is a narrow line Seyfert 1 (NLS1) galaxies, a group of AGNs with specific spectral characteristics. We analyze the light curves of the permitted Ha, Hb, optical Fe II line fluxes, and the continuum flux in order to search for a time lag between them. Additionally, in order to estimate the contribution of iron lines from different multiplets, we fit the Hb and Fe II lines with a sum of Gaussian components. We found that during the monitoring period the spectral variation (F_max/F_min) of Ark 564 was between 1.5 for Ha to 1.8 for the Fe II lines. The correlation between the Fe II and Hb flux variations is of higher significance than that of Ha and Hb (whose correlation is almost absent). The permitted-line profiles are Lorentzian-like, and did not change shape during the monitoring period. We investigated, in detail, the optical Fe II emission and found different degrees of correlation between the Fe II emission arising from different spectral multiplets and the continuum flux. The relatively weak and different degrees of correlations between permitted lines and continuum fluxes indicate a rather complex source of ionization of the broad line emission region.Comment: Accepted for publication in ApJ

Izbor doze hiperbaričkog kisika u liječenju glaukoma

The subjects in the study were 111 patients with open angle glaucoma who were submitted to treatment by hyperbaric oxygenation. Two groups were formed at random, an experimental one of 91 patients and a control group of 20 patients. The experimental group consisted of four subgroups classified according to the course of treatment they received: 31) sessions (31 patients), 20 sessions (20 patients), 15 sessions (20 patients) and 10 sessions (20 patients). For the treatment a large walk-in recompression chamber was utilized, once a day, at a pressure of 2.0 bars, for 90 minutes. Visual acuity and mean intraocular pressure values taken before and after hyperbaric oxygen treatment did not show a statistically significant difference either between the treated and control subjects, or at conlrol examinations after three and six months. During the follow-up period, changes in the visual field area in conlrol subjects were discrete and statistically not significant. At the same time the visual field values increased after the therapy in all the subgroups. In the 10-session course subgroup the increase was not statistically significant. In all other subgroups, statistical significance was at the level of P<0.01. Control after ihree months demonstrated the same level of statistical significance; control al the end of six months failed to show a statistically significant difference. The 20-session course is recommended for initial treatment. When visual field values return to 50 per cent of the improved values achieved during initial treatment, it is suggested that hyperbaric oxygen treatment be repeated.Istraživanje je obuhvatilo 111 bolesnika s glaukomom otvorenog kuta, podijeljenih u kontrolnu skupinu (20 bolesnika) i eksperimentalnu skupinu (91 bolesnik) s četiri podskupine za hiperbaričku oksigenaciju: od 30 seansi (31 bolesnik), 20 seansi (20 bolesnika), 15 seansi (20 bolesnika) i 10 seansi (20 bolesnika). Upotrijebljena je višemjesna stacionarna rekompresijska komora jednom na dan, na tlaku od 2,0 bara tijekom 90 minuta. Vidna oštrina i prosječna vrijednost intraokularnog tlaka prije i nakon hiperbaričkog tretmana nisu se statistički značajno razlikovale ni kod jedne skupine, što se održalo i na kontrolnim pregledima nakon tri i šest mjeseci. Tijekom razdoblja praćenja promjene površine vidnog polja bolesnika kontrolne skupine bile su diskretne i bez statističke značajnosti. U isto vrijeme povećale su se površine vidnog polja bolesnika eksperimentalne skupine nakon hiperbaričke oksigenncije u svim podskupinama. U seriji od 10 seansi hiperbaričke oksigenacije, povećanje vidnog polja nije bilo statistički značajno. U ostalim serijama hiperbaričke oksigenacije, statistička značajnost bila je na nivou P<0,01. Na kontrolnim pregledima nakon tri mjeseca očuvao se isti nivo statističke značajnosti, koji je nestao na pregledima nakon šest mjeseci. Preporučuje se u inicijalnom liječenju provesti niz od 20 seansi hiperbaričke oksigenacije. Kada vrijednosti vidnog polja opadnu na oko 50% poboljšanja postignutog u inicijalnom tretmanu, sugerira se ponavljanje hiperbaričke oksigenacije

Photo-centric variability of quasars caused by variations in their inner structure: Consequences on Gaia measurements

We study the photocenter position variability due to variations in the quasar inner structure. We consider variability in the accretion disk emissivity and torus structure variability due to different illumination by the central source. We discuss possible detection of these effects by Gaia. Observations of the photocenter variability in two AGNs, SDSS J121855+020002 and SDSS J162011+1724327 have been reported and discussed. With investigation of the variations in the quasar inner structure we explore how much this effect can affect the position determination and whether it can be (or not) detected with Gaia mission. We used (a) a model of a relativistic disk, including the perturbation that can increase brightness of a part of the disk, and consequently offset the photocenter position, and (b) a model of a dusty torus which absorbs and re-emits the incoming radiation from accretion disk. We estimated the value of the photocenter offset due to these two effects. We found that perturbations in the inner structure can significantly offset the photocenter. It depends on the characteristics of perturbation and accretion disk and structure of the torus. In the case of two considered QSOs the observed photocenter offsets cannot be explained by variations in the accretion disk and other effects should be considered. We discussed possibility of exploding stars very close to the AGN source, and also possibility that there are two variable sources in the center of these two AGNs that may indicate a binary super-massive black hole system on a kpc (pc) scale. The Gaia mission seems to be very perspective, not only for astrometry, but also for exploring the inner structure of AGNs. We conclude that variations in the quasar inner structure can affect the observed photocenter (up to several mas). There is a chance to observe such effect in the case of bright and low-redshifted QSOs.Comment: 12 pages, 8 figures, 3 tables. Accepted for publication in Astronomy and Astrophysics. Language improved, typos correcte

Long-term variability of the optical spectra of NGC 4151: I. Light curves and flux correlations

Results of a long-term spectral monitoring of the active galactic nucleus of NGC 4151 are presented (11 years, from 1996 to 2006). High quality spectra (S/N>50 in the continuum near Halpha and Hbeta) were obtained in the spectral range ~4000 to 7500 \AA, with a resolution between 5 and 15 A, using the 6-m and the 1-m SAO's telescopes (Russia), the GHAO's 2.1-m telescope (Cananea, Mexico), and the OAN-SPM's 2.1-m telescope (San-Pedro, Mexico). The observed fluxes of the Halpha, Hbeta, Hgamma and HeII emission lines and of the continuum at the observed wavelength 5117 A, were corrected for the position angle, the seeing and the aperture effects. We found that the continuum and line fluxes varied strongly (up to a factor 6) during the monitoring period. The emission was maximum in 1996-1998, and there were two minima, in 2001 and in 2005. The Halpha, Hgamma and He II fluxes were well correlated with the Hbeta flux. We considered three characteristic periods during which the Hbeta and Halpha profiles were similar: 1996-1999, 2000-2001 and 2002-2006. The line to continuum flux ratios were different; in particular during the first period, the lines were not correlated with the continuum and saturated at high fluxes. In the second and third period, where the continuum flux was small, the Halpha and Hbeta fluxes were well correlated to the continuum flux, meaning that the ionizing continuum was a good extrapolation of the optical continuum. The CCFs are often asymmetrical and the time lags between the lines and the continuum are badly defined indicating the presence of a complex BLR, with dimensions from 1 to 50 light-days.Comment: A&A, accepte

Spectral optical monitoring of 3C390.3 in 1995-2007: I. Light curves and flux variation of the continuum and broad lines

Here we present the results of the long-term (1995-2007) spectral monitoring of the broad line radio galaxy \object{3C~390.3}, a well known AGN with the double peaked broad emission lines, usually assumed to be emitted from an accretion disk. To explore dimensions and structure of the BLR, we analyze the light curves of the broad H$\alpha$ and H$\beta$ line fluxes and the continuum flux. In order to find changes in the BLR, we analyze the H$\alpha$ and H$\beta$ line profiles, as well as the change in the line profiles during the monitoring period. First we try to find a periodicity in the continuum and H$\beta$ light curves, finding that there is a good chance for quasi-periodical oscillations. Using the line shapes and their characteristics (as e.g. peaks separation and their intensity ratio, or FWHM) of broad H$\beta$ and H$\alpha$ lines, we discuss the structure of the BLR. Also, we cross-correlate the continuum flux with H$\beta$ and H$\alpha$ lines to find dimensions of the BLR. We found that during the monitoring period the broad emission component of the H$\alpha$ and H$\beta$ lines, and the continuum flux varied by a factor of $\approx$4-5. Also, we detected different structure in the line profiles of H$\alpha$ and H$\beta$. It seems that an additional central component is present and superposed to the disk emission. In the period of high activity (after 2002), H$\beta$ became broader than H$\alpha$ and red wing of H$\beta$ was higher than the one of H$\alpha$. We found time lags of $\sim$95 days between the continuum and H$\beta$ flux, and about 120 days between the continuum and H$\alpha$ flux. Variation in the line profiles, as well as correlation between the line and continuum flux during the monitoring period is in the favor of the disk origin of the broad lines with the possible contribution of some additional region and/or some kind of perturbation in the disk.Comment: 32 pages, accepted to A&A, typos correcte