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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.
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.
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.
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.
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.
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.
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.
Polymer electrolytes are a topic of interest because of their potential applications in electrochemical devices. However, very few systems exhibit both high conductivities and mechanical strength. Composite polymer electrolytes, composed of conventional polymer electrolytes and inert fillers, provide an avenue to enhance mechanical strength while maintaining ionic conductivity, if the particle sizes of these inert fillers are sufficiently small (< 1 μm in diameter). The determination of the morphology for these inert fillers in polymer matrixes was undertaken to further our understanding of ion transport phenomena in these composite systems. This paper presents an in situobservation of inert fillers in liquid media using environmental TEM.
Surface-modified fume silica was prepared by a two-step process. (1) SiCl4 was used to activate surface silanol (SiOH) groups and generate reactive SiCl groups on the surface of fume silica particles (Aldrich, 7 nm in diameter).
Boron nitride thin films have been deposited on (100) oriented Si substrate by magnetically enhanced activated reactive evaporation technique. The build up of c-BN is normally accompanied by strong compressive stresses. When these stresses exceeds the strength of the adhesion forces at the interface, adhesion fails causing the destruction of the c-BN film. This has been one of the major limiting factors of using the c-BN films for many important industrial applications such as cutting tools and semiconductor devices.
In this experiment, the plasma immersion ion implantation has been applied to improve the adhesion of the film. The post ion implantation was conducted at several implantation energies and constant dose. The effect of ion implantation on the microstructures was investigated by Fourier Transform Infrared spectroscopy and Transmission Electron Microscopy.
Infrared characterization of c-BN film by FTIR (Fig.l) shows that the IR spectra of the specimens prepared at all energies but 72 kV have strong absorption band at 1080 cm-1 corresponding to cubic boron nitride.
Despite the large production and consumption of textile fibers on a global basis, the ability to identify specific types of textile fibers with similar physical-chemical properties is a challenging obstacle for the textile industry. One problem in particular is the identification of specialty animal fibers. Cashmere is a specialty fiber that has a value of 7 to 8 times higher than its similar counterpart wool. It is important, therefore, for textile manufactures to be capable of distinguishing between bails of high value specialty fibers and those containing contamination from lower value products.
Today the universally accepted method of identifying fibers is microscopic analysis. However, the optical microscope is limited because of the subjective nature of the analysis and its limited ability to easily measure different parameters of the fiber such as the fiber diameter, the fiber scale length and the fiber scale thickness.
Potassium channels are ubiquitous ion channel proteins which play a crucial role in a broad spectrum of important cell functions. KcsA is a potassium channel found in the bacterium, Streptomyces lividan, and is believed to have only two transmembrane helices.
The KcsA protein has been cloned, overexpressed and purified to homogeneity, and reconstituted with phospholipids to form two-dimensional (2-D) crystals. Crystal samples were embedded in trehalose and examined in a cryo-holder (-170 °C) using a JEOL 4000EX electron microscope operated at 400kV in low dose mode. Images were recorded in spot scan-mode at a magnification of 60,000X, then digitized on a Perkin Elmer PDS flat bed microdensitometer and processed by using the MRC program suite. Processed images were brought to a common phase origin, and the amplitudes and phases from individual images were vectorially combined.
The emission spectrum from bioluminescent bacteria has been observed to depend on the type of bacteria. Photobacterium phosphoreum species usually show bioluminescence maxima around 472 nm and Photobacterium leiognathi species to slightly longer wavelength. A certain strain (Yl) of Vibrio fischeri, has a yellow bioluminescence with maximum at 542 nm. These differences have been explained as due to the bioluminescence originating from the fluorescence transition of an “antenna” protein, participating in the bioluminescence reaction along with the enzyme bacterial luciferase. The bioluminescence from a number of coelenterates involves a similar participation of an antenna protein, the famous “Green-Fluorescent Protein” being the origin of the bioluminescence emission from these organisms.
During the past twelve months RJ Lee Group has manually collected and published over one hundred thousand composite SEM images consisting of three components: a low magnification image, a high magnification image, and an x-ray spectrum. In addition, about one and one-half million discrete features have been automatically located and compositionally/morphologically characterized, with about one-fourth of those features then having ancillary images collected automatically based upon characterization criteria. Finally between ten and twenty thousand images have been collected for the production of image montages. The output of this effort has been systematically entered into networked databases where it is accessed for post-processing, analysis, and report generation.
Advanced metal coating methods have greatly improved the localization of secondary electrons (SEI) from biological specimens staged in an in-lens field emission SEM. Using these metal coatings, molecular level structural information from cell membranes and isolated bio-molecules have been more accurately recorded from frozen-hydrated samples due to the presence of bound water rather than from chemically fixed and dried samples. Although in-lens cryo-SEM systems have provided images with equivalent resolution to TEM-replicas, several conditions are encountered which require optimizing techniques and hardware.
A drop of hydrated Bakers yeast on a gold Balzers carrier was plunge-frozen in ethane at its melting point. Thermal properties of ethane, such as the large difference between melting and boiling points, and its low viscosity increase the heat transfer coefficient during plunging thereby leading to faster cooling of the sample than with other cryogens. Carriers were transferred to the cryo-workstation of the Oxford CT 3500 system.
Al films have been deposited on the inside of the Color Display Tube (CDT) panel on which black matrix carbon and RGB phosphors were coated to improve brightness with the prevention of voltage down and less ion impact to phosphors. The characteristics of Al films have a close relationship with the deposition variables such as base pressure and deposition rate causing changes in Al film microstructures and differences in the reflectance. It is generally known that the reflectance is affected by the thickness, grain size, and surface roughness of the Al film: The grain size of the Al film tends to decrease when base pressure is poor due to the presence of residual gas. The reflectance of Al alloys was reported to be increased with the larger grain size.
The purpose of this study is to understand the relationship between the reflectance and the microstructures of Al films as a function of base pressure in a CDT manufacturing to optimize deposition conditions for improved reflection properties.
Further development of Vacuum Fluorescent Displays (Fig.l) for low cost production and high yield requires investigation of all the components on a submicron scale at various processing stages.
A variety of specimen preparation methods have been used for making different types of high quality cross-sectional and plan-view TEM specimens from:
1. Initial phosphor materials - ZnCdS powders admixed with conducting powder of ln2O3;
2. In2O3 mixed ZnCdS phosphor layers of ready-made working VFD;
3. W - filament cathodes coated with (Ba,Sr,Ca) oxides.
Rapid sharing of results.
Group 1 specimens were made both by direct dispersion of phosphor powder particles on the carbon coated copper grid from acetone diluted powder suspension, and by preparation of cured bulk material from the powder using Gatan G-l epoxy, followed by cutting, grinding-dimpling and final ion milling in Gatan DuoMill 600 (Fig.2).
Microscopy is of vital importance in the real world of the forensic scientist. In today's society, physical evidence is critical to the criminal justice system for the detection, investigation and prosecution of criminal acts. A trail of microscopic fibers led investigators in Atlanta to the conviction of the serial killer, Wayne Williams. Flecks of paint on a hit-run victim, analyzed microscopically, can be compared with the paint on a suspect vehicle to exclude or match it to the crime. The forensic firearms examiner compares the microscopic striations on a bullet to match it to the gun it was fired from. Microscopes are used throughout the modern forensic laboratory. They are essential in searching for evidence. They aid the examiner in identifying and comparing trace evidence. As the scales of justice symbolize forensic science, microscopes symbolize the trace evidence examiner.
Because of the variety of physical evidence, forensic scientists use several types of microscopes in their investigations.