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We present the surface photometry of star clusters in the nearby dwarf elliptical galaxies NGC 185 and NGC 205, obtained from deep HST WFPC2 F555W (V) and F814W (I) images. We have obtained surface brightness and color profiles of six star clusters in NGC 185, seven star clusters in NGC 205, and one recently discovered non-stellar object in NGC 205. The surface brightness profiles of ten star clusters are fitted well by the King model, and those of four star clusters are fitted well by the power-law. Three out of ten star clusters fitted well with King model show signs of tidal tails.
We present a progress report of our wide field CCD survey of globular clusters in M31. We have covered a 3 deg × 3 deg area centered on M31, using the KPNO 0.9m and Washington CMT1 filters. Our survey is much deeper and more sensitive than previous surveys. We have found several hundred new globular cluster candidates in M31 in addition to confirming previously known globular clusters, and also have found a number of interlopers among previous globular cluster catalogs. We have also obtained spectra of about 500 objects among these candidates using HYDRA at the WIYN 3.5m telescope, which are used for classification and measuring the radial velocity of the candidate objects. When completed, a new master catalog of globular clusters in M31 will be made, combining the new globular clusters with the known globular clusters.
We present a progress report on Washington photometry of several hundred new globular cluster (GC) candidates in M31 which were recently found from our new CCD survey of GCs. The Washington CMT1 filters that we used are very efficient to survey extragalactic GCs and to estimate the metallicity of GCs. Preliminary color-magnitude diagrams and color-color diagrams of the new GC candidates and known GCs in M31 are obtained.
Searching for globular cluster candidates in nearby galaxies such as M31 is the first step to study the characteristics of extragalactic globular cluster systems. Previous searches for M31 globular clusters were mostly based on visual inspection of photograpic plates. We have selected globular cluster candidates from a wide-field Washington CCD survey of M31, using various methods: color-magnitude diagrams, color-color diagrams, point spread function subtraction and visual inspection of the objects. The efficiency and accuracy of these methods for finding globular clusters are presented.
We present a photometric study of the stars in ionizing star clusters embedded in several giant H II regions of M33 (CC93, IC 142, NGC 595, MA2, NGC 604 and NGC 588). Our photometry is based on the HST-WFPC2 images of these clusters. Color-magnitude diagrams and color-color diagrams of these clusters are obtained and are used for estimating the reddenings and ages of the clusters. The luminosity functions (LFs) and initial mass functions (IMFs) of the massive stars in these clusters are also derived. The slopes of the IMFs range from Γ = −0.5 to −2.1. Interestingly, it is found that the IMFs get steeper with increasing galactocentric distance and with decreasing [O/H] abundance.
The National Institute of Neurological Disease and Stroke-Canadian Stroke Network (NINDS-CSN) 5-minute neuropsychology protocol consists of only verbal tasks, and is proposed as a brief screening method for vascular cognitive impairment. We evaluated its feasibility within two weeks after stroke and ability to predict the development of post-stroke dementia (PSD) at 3 months after stroke.
We prospectively enrolled subjects with ischemic stroke within seven days of symptom onset who were consecutively admitted to 12 university hospitals. Neuropsychological assessments using the NINDS-CSN 5-minute and 60-minute neuropsychology protocols were administered within two weeks and at 3 months after stroke onset, respectively. PSD was diagnosed with reference to the American Heart Association/American Stroke Association statement, requiring deficits in at least two cognitive domains.
Of 620 patients, 512 (82.6%) were feasible for the NINDS-CSN 5-minute protocol within two weeks after stroke. The incidence of PSD was 16.2% in 308 subjects who had completed follow-up at 3 months after stroke onset. The total score of the NINDS-CSN 5-minute protocol differed significantly between those with and without PSD (4.0 ± 2.7, 7.4 ± 2.7, respectively; p < 0.01). A cut-off value of 6/7 showed reasonable discriminative power (sensitivity 0.82, specificity 0.67, AUC 0.74). The NINDS-CSN 5-minute protocol score was a significant predictor for PSD (adjusted odds ratio 6.32, 95% CI 2.65–15.05).
The NINDS-CSN 5-minute protocol is feasible to evaluate cognitive functions in patients with acute ischemic stroke. It might be a useful screening method for early identification of high-risk groups for PSD.
The YSTAR program is a general sky survey looking for variability. The main equipments are three 0.5-m telescopes. These telescopes have fast F/2 optics covering nearly 3.5 square degree field onto a 2K CCD. They also have very fast slew capability, which exceeds 10 degrees per second. These two factors make them most suitable for rapid target acquisition and wide-field surveys of various kinds. Our primary objective is to identify and monitor variable stars down to 18th R-magnitude, and our observing mode allows the same data set to be also useful in identifying asteroids. Our first telescope has just begun regular automated operation, and the second telescope will be installed in South Africa within this year to provide coverage of the southern sky.
Rutile nanoparticles have been synthesized by acid hydrolysis of titanium isopropoxide by low-temperature dissolution-reprecipitation process. High-resolution transmission electron micrographs of the rutile colloidal solution show needle-shaped rutile nanoparticles with the dimensions of 10–30 nm in diameter and 100–150 nm in length. X-ray diffraction (XRD) data show the existence of only the rutile polymorph in TiO2 powder with a crystallite size of 11.3 nm. The dielectric constant of rutile nanoparticles has been found to be 57 at 10 MHz AC frequency and DC conductance as 2.3 × 10−6 S/cm. Transmission electron micrographs and XRD data analysis imply that the rutile crystallites are self-organized in a regular fashion to produce multilayer three-dimensional linear clusters. The clusters have been found to be microporous (average porosity 1.4 nm) with high specific surface area (132.2 m2/g). At higher concentration, the clusters aggregate to produce interconnected network of star- or flower-like structures. This organized crystalline microporous metal-oxide semiconductor might find various practical applications.
The liquid phase plasma reduction method has been applied to prepare silver nanoparticles from a solution of silver nitrate (AgNO3) using a bipolar pulsed electrical discharge system. The excited states of atomic silver, hydrogen and oxygen as well as the molecular bands of hydroxyl radicals were detected in the emission spectra. As the discharge duration increased up to 10 min, silver particle peaks produced by surface plasmon absorption were observed around 430 nm. Both the particle size and the particle numbers were observed to increase with the length of the plasma treatment time and with the initial AgNO3 concentration. Spherical nanoparticles of about 5–20 nm in size were obtained with the discharging time of 5 min, whereas aggregates of nanoparticles of about 10–50 nm in size were mainly produced with the discharging time of 20 min. The cationic surfactant of cetyltrimethylammonium bromide (CTAB) added with the CTAB/AgNO3 molar ratio of 30% was shown to inhibit nanoparticle aggregation.
The ultraviolet (UV) color-color relation of early-type galaxies (ETGs) in the nearby universe (0.05 < z < 0.12) is re-examined with the latest GALEX GR6 and SDSS DR7 data. By drawing the FUV – NUV (as a measure of UV temperature) versus FUV – r (as a measure of UV amplitude) color-color diagram for the morphologically-cleaned, spectroscopically-cleaned sample of ~3700 quiescent ETGs, we find that the “old and dead“ ETGs consist of a well-defined sequence in UV colors, the “UV red sequence”, so that the stronger UV excess galaxies should have a harder UV spectral shape systematically. However, the observed UV spectral slope is too steep to be reproduced by the canonical models in which the UV flux is mainly controlled by age or metallicity parameters. The observed data support the helium enhancement scenario in which the UV spectral shape of UV upturn (FUV – NUV < 0.9; FUV – r ~ 6) galaxies may be governed by the minority population of helium-enhanced horizontal-branch (HB) stars.
Despite numerous previous studies, relationships between watershed land use and adjacent streams and rivers at various scales in Korea remain unclear. This study investigated the relationships between land uses and the physical, chemical, and biological characteristics of 720 sites of streams and rivers across the country. The land uses at two spatial scales, including a 1-km buffer and the base watershed management region (BWMR), were computed in a geographical information system (GIS) with a digital land use/land cover map. Characteristics of land uses at two spatial scales were then correlated with the monitored multidimensional characteristics of the streams and rivers. The results of this study indicate that land use types have significant effects on stream and river characteristics. Specifically, most characteristics were negatively correlated with the proportions of urban, rice paddy, agricultural, and bare soil areas and positively correlated with the amount of forest. The site-scale and BWMR-scale analyses suggest that BWMR land use patterns were more strongly related to ecological integrity than they were to site land use patterns. Improving our understanding of land use effects will largely depend on relating the results of site-specific studies that use similar response techniques and measures to evaluate ecological integrity. In addition, our results clearly indicate that the characteristics of streams and rivers are closely linked and that land use types differentially affect those characteristics. Thus, effective restoration and management for ecological integrity of lotic system should consider the physical, chemical, and biological factors in combination.
A pattern specific corrosion of aluminum wires was found during aluminum chemical mechanical polishing process. This paper presents and discusses the particular pattern dependency of the corrosion behavior and effective control methods in order to reduce the corrosion. An aluminum single damascene structure on silicon dioxide thin film was prepared and the effects of process variables and pattern configuration on corrosion behavior were extensively explored. The corrosion behavior was quantitatively analyzed using sheet resistance of corroded line. It was demonstrated that corrosion of aluminum wire was associated with cleaning media and pattern configuration. The area ratio between sub-micron size line and pads was the most important factors to determine the corrosion behavior. A post cleaning chemical including corrosion inhibitor couldn't prevent the corrosion perfectly. It was found that sacrificial dummy lines could reduce the aluminum corrosion, which suggests that the aluminum corrosion could be controlled by the structural consideration in aluminum damascene.
To enhance the lifetime of large-sized active matrix organic light emitting
diodes (AMOLEDs), we developed a liquid desiccant for encapsulation. The
liquid desiccant was prepared by mixing nano-sized calcium oxide (CaO)
powders and silicone binder including polyalkylalkenylsiloxane,
polyalkylhydrogensiloxane and platinum compound. It was confirmed that
liquid desiccant had an effect on absorption of penetrated moisture and
oxygen through calcium tests. Also, the test cells encapsulated with only
epoxy sealant dispensed at the edge of the cell developed dark spots within
100 hrs, which grew larger with time at 85 oC and 85 % R.H. On the other hand, the test cell sealed with epoxy
sealant and liquid desiccant showed no dark spots and retained 97% of its
initial luminance even after being stored for 800 hrs at 85 oC and 85 % R.H. Furthermore, the accelerating storage lifetimes of
31-inch bottom-emitting AMOLEDs with epoxy sealant and liquid desiccant
showed about 1000 hrs. These results suggest that the liquid desiccant can
be applied to encapsulation of large-sized AMOLEDs.
The complex dielectric constants of several π-conjugated materials were measured, and generalized Langevin equation was used to analyze the dielectric behavior in the frequency domain. From the results of the fitting the experimental data using the generalized Langevin equation, we suggest that the charge carriers are electrically screened by the neighboring charges through the structural relaxation, and the carriers are not interact each other. We confirmed that the generalized Langevin equation offers a very good approach to analyze and understand the transport properties of charge carriers in π-conjugated materials.
We offer a synthesis of novel nanocrystalline ZnBiVO4 using hydrothermal method. The same novel catalyst was synthesized using solid-state route for the first time. We have exemplified the hydrothermal synthesis of this new compound using zinc nitrate, bismuth nitrate and ammonium metavanadate. The ZnBiVO4 was synthesized using zinc oxide, bismuth oxide and vanadium oxide by solid-state route. X-ray difractometry for its structural study and Scanning Electron Microscopy for the particle morphology characterized the resultant product. The prima facie observations revealed the formation of tetragonal crystallites of hydrothermal ZnBiVO4 ranging from 40-50nm. The BET surface area of hydrothermal ZnBiVO4 was increased 9 times as compared to solid state ZnBiVO4. The steepness of the UV-visible DRS Diffuse Reflectance Spectra) absorption edge, suggests the good crystalline nature of the material. From the photodecomposition of H2S, it is noteworthy that the hydrogen evolution was enhanced by 70% in hydrothermal ZnBiVO4.