Deep H alpha images of interacting galaxies

Gravitational interactions between galaxies are believed to increase star formation activity dramatically, and most of the brightest starburst galaxies show clear signs of recent interactions. However, it is still not known how interaction triggers star formation, nor are there models to relate the type or strength of interaction to the location or amount of star formation. We report on a series of deep H alpha images of interacting and post-interaction galaxies which we took with the purpose of finding the young stars and ionized gas in these objects. We were motivated in part by the hope that by studying the very recently formed stars we could see how the interaction process had affected the star formation. We observed the galaxies through 50 A-wide filters, one on the redshifted H alpha line and one off, and a standard R filter. Depending on the galaxy and conditions, images in the B, V, and I filters were also obtained. The images were recorded with a 4x7 ft. or 17 ft. diameter CCD at the 1-meter telescope of the Wise Observatory in Mitzpe Ramon. The H alpha and continuum images are used, together with observations at other wavelengths, to put together as complete a picture as possible of star formation and interactions in each galaxy. The complete observation set is not yet available for all the galaxies but certain results are already clear. There do not seem to be any correlations between H 1 and H alpha structures. In some H 1 plume galaxies H alpha extensions were seen on the other side of the galaxy from the H 1; in others extensive H alpha filaments have been found but not H 1. The preliminary results agree with the simplest model that interaction-induced star formation will be concentrated in the system center, since that is where the mass ends up

Nova V1425 Aquilae 1995 - The Early Appearance of Accretion Processes in An Intermediate Polar Candidate

Continuous CCD photometry of Nova Aquilae 1995 was performed through the standard B,V,R and I filters during three nights in 1995 and with the I filter during 18 nights in 1996. The power spectrum of the 1996 data reveals three periodicities in the light curve: 0.2558 d, 0.06005 d and 0.079 d, with peak-to-peak amplitudes of about 0.012, 0.014 and 0.007 mag. respectively. The two shorter periods are absent from the power spectrum of the 1995 light curve, while the long one is probably already present in the light curve of that year. We propose that V1425 Aql should be classified as an Intermediate - Polar CV. Accordingly the three periods are interpreted as the orbital period of the underlying binary system, the spin period of the magnetic white dwarf and the beat period between them. Our results suggest that no later than 15 months after the outburst of the nova, accretion processes are taking place in this stellar system. Matter is being transferred from the cool component, most likely through an accretion disc and via accretion columns on to the magnetic poles of the hot component.Comment: 7 pages, 4 eps. figures, Latex, accepted for publication in MNRA

Dynamic mechanical properties of crosslinked natural rubber composites reinforced with cellulosic nanoparticles

The dynamic mechanical analysis (DMA) of crosslinked natural rubber nanocomposites reinforced with cellulosic nanoparticles obtained from lignocelluloses biomass (coconut husk, bamboo culm and cotton linters) has been investigated and compared with carbon black filled natural rubber vulcanizate. The crosslinked natural rubber matrix based composites were produced by melt intercalation process using two roll mixing mill and vulcanized in a thermally regulated hydraulic press. DMA were carried out in order to obtain their viscoelastic thermo-mechanical spectrum. Results showed decrease in storage modulus (E’) with increasing temperature while glass transition temperatures (Tg) obtained from temperature dependence loss tangent curves were -35.84, 37.30, -34.61, -35.27 and -34.29 oC for neat- natural rubber (NR), natural rubber reinforced carbon black (NR-CB), natural rubber reinforced bamboo cellulosic particles (NR-BNC), natural rubber reinforced coconut husk cellulosic particles (NR-CHNC) and natural rubber reinforced cotton linter particles (NR-CLNC) respectively. The composite of NR-CHNC was also found to give a higher damping factor of 1.563 compared to NR-CB which gave a value of 1.518. nanocomposites reinforced with cellulosic nanoparticles can provide adequate synergy for loading bearing and vibration isolation application.Keywords: Dynamic Mechanical Properties; Damping; Nanocomposites; Grass Transition Temperature

Calcined Corncob-Kaolinite Combo as New Sorbent for Sequestration of Toxic Metal Ions From Polluted Aqua Media and Desorption

This study investigated a new area of improving the adsorption capacity of clay using corn cob as an alternative means of clay modification to the more expensive and complicated chemical treatment techniques. Kaolinite Clay (KC), Calcined corncob-kaolinite Combo (CCKC), and Corncob (CC) adsorbents were utilized. The adsorbents were characterized by Fourier Transform-Infrared (FT-IR) Spectroscopy, Scanning Electron Microscopy (SEM), X-ray fluorescence spectroscopy, and Brunauer-Emmett-Teller (BET) surface area analyzer. Batch adsorption methodology was used to investigate the effect of pH, initial metal concentration, adsorbent dose, and contact time on adsorption of Pb (II) and Cd (II). A slight increase in BET surface area of 29.31 m2/g for CCKC from 14.12 m2/g for raw KC was achieved. The trend of metal adsorption on the adsorbents was in the order CC>CCKC>KC. The Langmuir isotherm was found to present the best fit for the unmodified adsorbents while the Freundlich was applicable for CCKC indicating multilayer heterogeneous surface. The pseudo second order kinetic model was found to be suitable in the kinetic analysis. Thermodynamic studies revealed a spontaneous physical adsorption process of metal ions on CCKC. The combo adsorbent showed highest percentage desorption (>70%) of Cd and Pb ions in both acid and basic media compared to the other adsorbents. The results of the study established the efficiency of calcined corn cob kaolinite combo as suitable adsorbent for metal ions

Adsorption mechanism and modeling of radionuclides and heavy metals onto ZnO nanoparticles: a review

Abstract The contamination of environmental waters with heavy metals and radionuclides is increasing because of rapid industrial and population growth. The removal of these contaminants from water via adsorption onto metal nanoparticles is an efficient and promising technique to abate the toxic effects associated with these pollutants. Among metal nanoparticle adsorbents, zinc oxide nanoparticles (ZnONPs) have received tremendous attention owing to their biocompatibility, affordability, long-term stability, surface characteristics, nontoxicity, and powerful antibacterial activity against microbes found in water. In this review, we considered the adsorption of heavy metals and radionuclides onto ZnONPs. We examined the isotherm, kinetic, and thermodynamic modeling of the process as well as the adsorption mechanism to provide significant insights into the interactions between the pollutants and the nanoparticles. The ZnONPs with surface areas (3.93 to 58.0 m2/g) synthesized by different methods exhibited different adsorption capacities (0.30 to 1500 mg/g) for the pollutants. The Langmuir and Freundlich isotherms were most suitable for the adsorption process. The Langmuir separation factor indicated favorable adsorption of all the pollutants on ZnONPs. The pseudo-second-order kinetics presented the best for the adsorption of the adsorbates with regression values in the range of 0.986–1.000. Spontaneous adsorption was obtained in most of the studies involving endothermic and exothermic processes. The complexation, precipitation, ion exchange, and electrostatic interactions are the probable mechanisms in the adsorption onto ZnONPs with a predominance of complexation. The desorption process, reusability of ZnONPs as well as direction for future investigations were also presented

Metformin mitigates the impaired development of skeletal muscle in the offspring of obese mice

Background: Maternal obesity is linked with offspring obesity and type 2 diabetes. Skeletal muscle (SM) insulin resistance is central to the development of diabetes. Adenosine monophosphate (AMP)-activated protein kinase (AMPK) is inhibited in SM of fetuses born to obese mothers

MACHO Alert 95-30 : First Real-Time Observation of Extended Source Effects in Gravitational Microlensing

We present analysis of MACHO Alert 95-30, a dramatic gravitational microlensing event towards the Galactic bulge whose peak magnification departs significantly from the standard point-source microlensing model. Alert 95-30 was observed in real-time by the Global Microlensing Alert Network (GMAN), which obtained densely sampled photometric and spectroscopic data throughout the event. We interpret the light-curve ``fine structure'' as indicating transit of the lens across the extended face of the source star. This signifies resolution of a star several kpc distant. We find a lens angular impact parameter theta_{min}/theta_{source} = 0.715 +/- 0.003. This information, along with the radius and distance of the source, provides an additional constraint on the lensing system. Spectroscopic and photometric data indicate the source is an M4 III star of radius 61 +/- 12 Rsun, located on the far side of the bulge at 9 kpc. We derive a lens angular velocity, relative to the source, of 21.5 +/- 4.9 km/s/kpc, where the error is dominated by uncertainty in the source radius. Likelihood analysis yields a median lens mass of 0.67{+2.53}{-0.46} Msun, located with 80% probability in the Galactic bulge at a distance of 6.93{+1.56}{-2.25} kpc. If the lens is a main-sequence star, we can include constraints on the lens luminosity. This modifies our estimates to M_lens = 0.53{+0.52}{-0.35} Msun and D_lens = 6.57{+0.99}{-2.25} kpc. Spectra taken during the event show that the absorption line equivalent widths of H alpha and the TiO bands near 6700 A vary, as predicted for microlensing of an extended source. This is most likely due to center-to-limb variation in the stellar spectral lines. These data demonstrate the feasibility of using microlensing limb crossings as a tool to probe stellar atmospheres directly.Comment: 32 pages including 6 tables, and 15 figures; Uses AASTeX 4.0; submitted to The Astrophysical Journa

Multiwavelength observations of short time-scale variability in NGC 4151. IV. Analysis of multiwavelength continuum variability

This paper combines data from the three preceding papers in order to analyze the multi-waveband variability and spectral energy distribution of the Seyfert~1 galaxy NGC~4151 during the December 1993 monitoring campaign. The source, which was near its peak historical brightness, showed strong, correlated variability at X-ray, ultraviolet, and optical wavelengths. The strongest variations were seen in medium energy ($\sim$1.5~keV) X-rays, with a normalized variability amplitude (NVA) of 24\%. Weaker (NVA = 6\%) variations (uncorrelated with those at lower energies) were seen at soft $\gamma$-ray energies of $\sim$100~keV. No significant variability was seen in softer (0.1--1~keV) X-ray bands. In the ultraviolet/optical regime, the NVA decreased from 9\% to 1\% as the wavelength increased from 1275~\AA\ to 6900~\AA. These data do not probe extreme ultraviolet (1200~\AA\ to 0.1~keV) or hard X-ray (2--50~keV) variability. The phase differences between variations in different bands were consistent with zero lag, with upper limits of \ls0.15~day between 1275~\AA\ and the other ultraviolet bands, \ls0.3~day between 1275~\AA\ and 1.5~keV, and \ls1~day between 1275~\AA\ and 5125~\AA. These tight limits represent more than an order of magnitude improvement over those determined in previous multi-waveband AGN monitoring campaigns. The ultraviolet fluctuation power spectra showed no evidence for periodicity, but were instead well-fitted with a very steep, red power-law ($a = -2.5$). If photons emitted at a ``primary" waveband are absorbed by nearby material and ``reprocessed" to produce emission at a secondary waveband, causality arguments require that variations in the secondary band follow those in the primary band. The tight interband correlation and limits on the ultraviolet andComment: 35 pages, LaTeX (including aaspp4), including 7 PostScript figures; To appear in the ApJ (October 20, 1996) Vol. 47