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We report on new observations of the globular cluster systems (GCSs) of two galaxies: M86 (NGC 4406) in Virgo and NGC 4696, the central giant elliptical (gE) in the Centaurus cluster. Previous observations in M86 showed no evidence for bimodality, but using only (V - I) for small cluster samples. The NGC 4696 GCS is unstudied. We used the integrated Washington (C - T1) color. This metallicity index is more than twice as sensitive to [Fe/H] as (V - I). In M86 we have about 1100 good GC candidates, and about 650 in NGC 4696, with mean internal metallicity errors ~ 0.15 dex. Both of these GCSs are found to have bimodal metallicity distributions (MDs). Our data strengthen previous results that MDs for the GCSs of gEs are widespread. The evidence for 2 separate populations in these galaxies is corroborated by examining the surface density distributions: the metal-rich clusters are more centrally concentrated than their metal-poor counterparts. The overall radial metallicity gradient present in the M86 GCS is due to the varying radial mix of the 2 populations. The existence of 2 GC populations signifies that there were 2 distinct epochs or events of cluster formation in a gE. The simple collapse model of gE formation is ruled out.
There are known to be several giant elliptical galaxies with high globular cluster specific frequencies, which possess about three or more times the normal number of globular clusters for their luminosity. The origin of high specific frequency globular cluster systems is not yet known.
Through time-series CCD photometry of the globular cluster M 53, we have discovered eight new SX Phoenicis type stars. All the new SX Phoenicis stars are located in the blue straggler star region in the color-magnitude diagram of M 53. In addition, we have obtained light curves for 45 known RR Lyrae stars.
A new donor-acceptor structured conjugated polymer (PDODTBI) with trifluoromethylated benzimidazole and benzo[1,2-b;3,4-b']dithiophene (BDT) unit have been designed and synthesized using Stille coupling polymerization reaction. The polymer is highly soluble in common organic solvents such as chloroform, tetrahydrofuran and chlorobenzene with good film forming properties. The structure of the polymer is elucidated by 1H NMR and FTIR spectroscopic techniques. The introduction of a trifluoromethyl group at 4th position of the benzimidazole unit has significantly altered the optical and electrochemical properties of polymer. Polymer film showed broad absorption band in the range of 400-680 nm. Optical band gap of the polymer estimated from the absorption band edge and is found to be ∼1.88 eV. Polymer exhibited deeper HOMO (-5.0 eV) and the LUMO (-3.12 eV) energy levels. Bulk heterojunction (BHJ) solar cell device with PDODTBI as a donor and PC61BM as an acceptor were evaluated.
While multiple DNase activities occur in the excretory/secretory products (ESPs) of the adult Haemonchus contortus, the DNase activities in ESPs of the infective larvae (L3) have not been studied. Thus, the DNase activities in ESPs of H. contortus L3 were investigated and compared to those of adults for developmental stage-specific analysis. The DNase activities had relative molecular masses (Mrs) of 34 and 36 kDa upon zymographic analysis at pH 5.0 and 7.0 when the larvae were incubated for over 48 h. The 34 and 36 kDa DNases of L3 ESPs were also detected in adult ESPs with similar characteristics. However, the 37 and 38.5 kDa DNases of the adult ESPs were not detected in the L3 ESPs. Since the 37 and 38.5 kDa DNase activities were mainly detected in adult ESPs, these activities appear to be specific to the adult stage whereas the other ESP DNase activities appear to be expressed during multiple stages of the parasite's life cycle. While the difference in DNase activities of L3 and adults remains obscure, the role of DNase in larval development should be further clarified and the identification of stage-specific developmental markers will lead to the discovery of specific factors that stimulate larval development.
In the last decade we witness an advent of new types of dwarf stellar systems including ultra-compact dwarfs, ultra-faint dwarf spheroidals, and exotic globular clusters, breaking the old simple paradigm for dwarf galaxies and globular clusters. These objects be- come more intriguing, and understanding of these new findings becomes more challenging. Recently we discovered a new type of large scale structure in the Virgo cluster of galaxies: it is composed of globular clusters. Globular clusters in Virgo are found wandering between galaxies (intracluster globular clusters) as well as in galaxies. These intracluster globular clusters fill a significant fraction in the area of the Virgo cluster and they are dominated by blue globular clusters. These intracluster globular clusters may be closely related with the first dwarf galaxies in the universe.
With advancement of infrared space telescopes during the past decade, infrared wavelength
regime has been a focal point to study various properties of galaxies with respect to
evolution of galaxies. Polycyclic Aromatic Hydrocarbons (PAHs) have emerged as one of the
most important features since these features dominate the mid-infrared spectra of
galaxies. These PAH features provide a great handle to calibrate star formation rates and
diagnose ionized states of grains. However, the PAH 3.3 μm feature has
not been studied as much as other PAH features since it is weaker than others and resides
outside of Spitzer capability, although it will be the only PAH feature accessible by JWST
for high-z galaxies. AKARI mJy Unbiased Survey of Extragalactic Sources in 5MUSES (AMUSES)
intends to take advantage of AKARI capability of spectroscopy in the
2 ~ 5 μm to provide an unbiased library of 44 sample
galaxies selected from a parent sample of 5MUSES, one of Spitzer legacy projects. For
these 3.6 μm flux limited sample galaxies whose redshifts range between
0 < z < 1, AMUSES will calibrate PAH 3.3
μm as a star formation rate (SFR) indicator while measuring ratios
between PAH features. We present preliminary results of AMUSES.
The p-type Te-doped Bi0.5Sb1.5Te3 and n-type SbI3-doped Bi2Te2.85Se0.15 thermoelectric compounds were fabricated by hot pressing in the temperature range of 380 to 440 °C under 200 MPa in Ar. Both the compounds were highly dense and showed high crystalline quality. The grains of the compounds were preferentially oriented and contained many dislocations through the hot pressing. The fracture path followed the transgranular cleavage planes, which are perpendicular to the c-axis. In addition, with increasing the pressing temperature, the figure of merit was increased. The highest values of figure of merit for the p- and n-type compounds, which were obtained at 420 °C, were 2.69 × 10−3/K and 2.35×10−3/K, respectively.
The p-type Bi0.5Sb1.5Te3 compounds with Te dopant (4.0 and 6.0 wt%) and without dopant were fabricated by hot extrusion in the temperature range of 300 to 510 °C under an extrusion ratio of 20:1. The undoped and Te doped compounds were highly dense and showed high crystalline quality. The grains contained many dislocations and were fine equiaxed (˜ 1.0 μm) owing to the dynamic recrystallization during the extrusion. The hot extrusion gave rise to the preferred orientation of grains. The bending strength and the figure of merit of the undoped and Te doped compounds were increased with increasing the extrusion temperature. The Te dopant significantly increased the figure of merit. The values of the figure of merit of the undoped and 4.0 wt% Te-doped compounds hot extruded at 440 °C were 2.11×10−3/K and 2.94×10−3/K, respectively.
Semiconducting iron silicide dots with dimensions ranging between 5 and 100 nm can be obtained by ion implantation on Si wafers and exhibit interesting photo- and electro- luminescent properties.
In our study we use structural and optical characterization as well as theoretical modelling in order to: i) discriminate among intrinsic effects of FeSi2 dots and effects due to lattice damage and Si matrix; ii) identify the range of physical parameters (size, phase, electronic structure) corresponding to the luminescent dots.
Low-defect-density polycrystalline Si on flexible substrates can be instrumental in realizing the full potential of macroelectronics. Direct deposition or solid-phase crystallization techniques are often incompatible with polymers and produce materials with high defect densities. Excimer-laser annealing is capable of producing films of reasonable quality directly on polymer and metallic substrates. Sequential lateral solidification (SLS) is an advanced pulsed-laser-crystallization technique capable of producing Si films on polymers with lower defect density than can be obtained via excimer-laser annealing. Circuits built directly on polymers using these SLS films show the highest performance reported to date.
A study of the prepolished surface of γ-TiAl specimens superplastically deformed in tension showed evidence of macroscopic surfaces at which grain boundary sliding occurs. In a scanning electron microscope these surfaces are observed as black bands on the deformed surface because of the difference in the appearance of these bands and grain regions situated in between these bands. It has been suggested that cooperative grain boundary sliding, i.e., sliding of grain groups, occurs during superplastic deformation, giving rise to these bands.
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