Study of sorption properties of lignin-derivatized fibrous coposites for the remediation of oil polluted receiving waters

The sorption properties of lignin-wool composites towards oil pollution at different concentrations of the contamination were studied. The release ability of oil pollutant was studied by a gravimetric method and by determining the chemical oxygen demand of cleaned water. It has been established that technical hydrolysis lignin–wool composites display a low release ability of oil-based pollutants and a slow rate for achieving release equilibrium

Immobilization of Trichosporon cutaneum R 57 Cells onto Methylcellulose/SiO2 Hybrids and Biosorption of Cadmium and Copper Ions

Methylcellulose/Silica (MC/SiO2) hybrids were synthesized via poly step sol-gel method. SiO2 was included into the hybrids from two silica precursors - methyltriethoxysilane (MTES) and ethyltrimethoxysilane (ETMS) with different quantity of organic part-5, 20 and 50 wt.%. The filamentous yeasts Trichosporon cutaneum strain R 57 was immobilized onto the synthesized MC/SiO2 hybrids. After immobilization the hybrid materials were used in the processes of sorption of cadmium and copper ions. The obtained results of protein content analysis indicated that the amount of protein increased with increasing of MC in the hybrids. It was established that the maximal efficiency of copper and cadmium removal were observed for hybrid materials containing MTES and 50 wt.% MC - 66% and 26% respectively. For ETMS and 50 wt.% MC a high value of copper removal was 56% and for cadmium - 45% removal, respectively. FTIR analysis of free and immobilized cells with metal ions was conducted. SEM images showed successful immobilization of the yeasts cells. Second order model was employed in order to investigate the kinetics of copper and cadmium biosorption

Detectability of low energy X-ray spectral components in type 1 AGN

In this paper we examine the percentage of type 1 AGN which require the inclusion of a soft excess component and/or significant cold absorption in the modelling of their X-ray spectra obtained by XMM-Newton. We do this by simulating spectra which mimic typical spectral shapes in order to find the maximum detectability expected at different count levels. We then apply a correction to the observed percentages found for the Scott et al. (2011) sample of 761 sources. We estimate the true percentage of AGN with a soft excess component to be 75+/-23%, suggesting that soft excesses are ubiquitous in the X-ray spectra of type 1 AGN. By carrying out joint fits on groups of low count spectra in narrow z bins in which additional spectral components were not originally detected, we show that the soft excess feature is recovered with a mean temperature kT and blackbody to power-law normalisation ratio consistent with those of components detected in individual high count spectra. Cold absorption with nH values broadly consistent with those reported in individual spectra are also recovered. We suggest such intrinsic cold absorption is found in a minimum of ~5% of type 1 AGN and may be present in up to ~10%.Comment: 10 pages, 6 figures, 4 tables. Accepted for publication in MNRA

Mapping the radial structure of AGN tori

We present mid-IR interferometric observations of 6 type 1 AGNs at multiple baseline lengths of 27--130m, reaching high angular resolutions up to lambda/B~0.02 arcseconds. For two of the targets, we have simultaneous near-IR interferometric measurements as well. The multiple baseline data directly probe the radial distribution of the material on sub-pc scales. Within our sample, which is small but spans over ~2.5 orders of magnitudes in the UV/optical luminosity L of the central engine, the radial distribution clearly and systematically changes with luminosity. First, we show that the brightness distribution at a given mid-IR wavelength seems to be rather well described by a power law, which makes a simple Gaussian or ring size estimation quite inadequate. Here we instead use a half-light radius R_1/2 as a representative size. We then find that the higher luminosity objects become more compact in normalized half-light radii R_1/2 /R_in in the mid-IR, where R_in is the dust sublimation radius empirically given by the L^1/2 fit of the near-IR reverberation radii. This means that, contrary to previous studies, the physical mid-IR emission size (e.g. in pc) is not proportional to L^1/2, but increases with L much more slowly, or in fact, nearly constant at 13 micron. Combining the size information with the total flux specta, we infer that the radial surface density distribution of the heated dust grains changes from a steep ~r^-1 structure in high luminosity objects to a shallower ~r^0 structure in those of lower luminosity. The inward dust temperature distribution does not seem to smoothly reach the sublimation temperature -- on the innermost scale of ~R_in, a relatively low temperature core seems to co-exist with a slightly distinct brightness concentration emitting roughly at the sublimation temperature.Comment: accepted for publication in A&

Probing the unified model in NGC 7314

We present a study of the complex absorbed X-ray spectrum of the Narrow Line Seyfert 1 galaxy NGC 7314. We collected available public X-ray data from the archives of XMM-Newton, Suzaku, and ASCA. The spectra were analyzed using the fitting package SPEX. We find evidence of intrinsic neutral and ionized absorption in the XMM-Newton EPIC-pn spectrum. The ionized gas presents three significantly distinct ionization phases, although its kinematic properties could not be disentangled. At least two of these phases are also detected in the RGS spectrum, although with less significance due to the low statistics. The ASCA and Suzaku spectra show larger neutral absorption but no ionized gas signatures. The Fe Kalpha emission line is detected in all the observations and, additionally, Fe XXVI in the EPIC-pn spectrum, and Fe Kbeta in the Suzaku XIS spectrum. Using this observational evidence we construct a consistent picture of the geometry of the system in the context of the unified model of active galactic nuclei. The different observational properties are thus interpreted as clouds of neutral gas moving across our line of sight, which would be grazing a clumpy dusty torus.Comment: 9 pages, 8 figures. Accepted for publication in Astronomy and Astrophysic

Spitzer mid-infrared spectroscopy of compact symmetric objects: What powers radio-loud active galactic nuclei?

We present low- and high-resolution mid-infrared (mid-IR) spectra and photometry for eight compact symmetric objects (CSOs) taken with the Infrared Spectrograph on the Spitzer Space Telescope. The hosts of these young, powerful radio galaxies show significant diversity in their mid-IR spectra. This includes multiple atomic fine-structure lines, H2 gas, polycyclic aromatic hydrocarbon (PAH) emission, warm dust from T = 50 to 150 K, and silicate features in both emission and absorption. There is no evidence in the mid-IR of a single template for CSO hosts, but 5/8 galaxies show similar moderate levels of star formation (<10 M_sun/yr from PAH emission) and silicate dust in a clumpy torus. The total amount of extinction ranges from A_V ~ 10 to 30, and the high-ionization [Ne V] 14.3 and 24.3 um transitions are not detected for any galaxy in the sample. Almost all CSOs show contributions both from star formation and active galactic nuclei (AGNs), suggesting that they occupy a continuum between pure starbursts and AGNs. This is consistent with the hypothesis that radio galaxies are created following a galactic merger; the timing of the radio activity onset means that contributions to the IR luminosity from both merger-induced star formation and the central AGN are likely. Bondi accretion is capable of powering the radio jets for almost all CSOs in the sample; the lack of [Ne V] emission suggests an advection-dominated accretion flow mode as a possible candidate. Merging black holes (BHs) with M_BH > 10^8 M_sun likely exist in all of the CSOs in the sample; however, there is no direct evidence from these data that BH spin energy is being tapped as an alternative mode for powering the radio jets.Comment: 22 pages, 14 figures; published in Ap

Infrared Spectral Energy Distributions of Seyfert Galaxies: Spitzer Space Telescope Observations of the 12 micron Sample of Active Galaxies

The mid-far-infrared spectral energy distributions (SEDs) of 83 active galaxies, mostly Seyfert galaxies, selected from the extended 12 micron sample are presented. The data were collected using all three instruments, IRAC, IRS, and MIPS, aboard the Spitzer Space Telescope. The IRS data were obtained in spectral mapping mode, and the photometric data from IRAC and IRS were extracted from matched, 20 arcsec diameter circular apertures. The MIPS data were obtained in SED mode, providing very low resolution spectroscopy (R ~ 20) between ~ 55 and 90 microns in a larger, 20 by 30 arcsec synthetic aperture. We further present the data from a spectral decomposition of the SEDs, including equivalent widths and fluxes of key emission lines; silicate 10 and 18 micron emission and absorption strengths; IRAC magnitudes; and mid-far infrared spectral indices. Finally, we examine the SEDs averaged within optical classifications of activity. We find that the infrared SEDs of Seyfert 1s and Seyfert 2s with hidden broad line regions (HBLR, as revealed by spectropolarimetry or other technique) are qualitatively similar, except that Seyfert 1s show silicate emission and HBLR Seyfert 2s show silicate absorption. The infrared SEDs of other classes with the 12 micron sample, including Seyfert 1.8-1.9, non-HBLR Seyfert 2 (not yet shown to hide a type 1 nucleus), LINER and HII galaxies, appear to be dominated by star-formation, as evidenced by blue IRAC colors, strong PAH emission, and strong far-infrared continuum emission, measured relative to mid-infrared continuum emission.Comment: 78 pages, 13 figure

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A Model for Type 2 Coronal Line Forest (CLiF) AGNs

We present a model for the classification of Coronal Line Forest Active Galactic Nuclei (CLiF AGNs). CLiF AGNs are of special interest due to their remarkably large number of emission lines, especially forbidden highionization lines (FHILs). Rose et al. suggest that their emission is dominated by reflection from the inner wall of the obscuring region rather than direct emission from the accretion disk. This makes CLiF AGNs laboratories to test AGN-torus models. Modeling an AGN as an accreting supermassive black hole surrounded by a cylinder of dust and gas, we show a relationship between the viewing angle and the revealed area of the inner wall. From the revealed area, we can determine the amount of FHIL emission at various angles. We calculate the strength of [Fe VII]λ6087 emission for a number of intermediate angles (30°, 40°, and 50°) and compare the results with the luminosity of the observed emission line from six known CLiF AGNs. We find that there is good agreement between our model and the observational results. The model also enables us to determine the relationship between the type 2:type 1 AGN fraction vs the ratio of torus height to radius, h/r

High-resolution mapping of the physical conditions in two nearby active galaxies based on 12CO(1-0), (2-1) and (3-2) lines

We present a detailed analysis of high resolution observations of the three lowest CO transitions in two nearby active galaxies, NGC4569 and NGC4826. The CO(1-0) and (2-1) lines were observed with the Plateau de Bure Interferometer and the CO(3-2) line with the Submillimeter Array. Combining these data allows us to compare the emission in the three lines and to map the line ratios, R21=I_{CO(2-1)}/I_{CO(1-0)} and R32=I_{CO(3-2)}/I_{CO(1-0)} at a resolution of ~2", i.e., a linear resolution of 160 pc for NGC4569 and 40 pc for NGC4826. In both galaxies the emission in the three lines is similarly distributed spatially and in velocity, and CO is less excited (R32<0.6) than in the Galactic Center or the centers of other active galaxies studied so far. According to a pseudo-LTE model the molecular gas in NGC4569 is cold and mainly optically thick in the CO(1-0) and (2-1) lines; less than 50% of the gas is optically thin in the CO(3-2) line. LVG modeling suggests the presence of an elongated ring of cold and dense gas coinciding with the ILR of the stellar bar. More excited gas is resolved in the circumnuclear disk of NGC4826. According to our pseudo-LTE model this corresponds to warmer gas with a ~50% of the CO(3-2) emission being optically thin. LVG modeling indicates the presence of a semicircular arc of dense and cold gas centered on the dynamical center and ~70 pc in radius. The gas temperature increases and its density decreases toward the center. A near side/far side asymmetry noticeable in the CO, R32 and Pa-alpha maps suggests that opacity effects play a role. Examining published CO maps of nearby active galaxies we find similar asymmetries suggesting that this could be a common phenomenon in active galaxies. These mainly qualitative results open new perspectives for the study of active galaxies with the future Atacama Large Millimeter/submillimeter Array.Comment: accepted for publication in A&