LS 4825: A blue supergiant on the far side of the galaxy

We present high-resolution spectroscopic observations of LS 4825, a V = 12 B-type star in the Galactic center direction. On the basis of its stellar and interstellar spectra, we infer that it is likely to be a young supergiant at a distance of 21 +/- 5 kpc, and hence lying on the far side of the 'Galaxy. Adopting this hypothesis, a differential abundance analysis shows LS 4825 to have a chemical composition that is consistent with local B-type supergiants. These observations therefore represent the first detailed investigation of a star on the far side of the Galactic center. We trace multiple interstellar components in Ca II K and Na I D spectra, with velocities -206 less than or equal to v(lst) less than or equal to +93 km s(-1). We consider the likely origin of this gas and find that some components appear to trace matter lying close to the Galactic center. We discuss the possible use of such sight lines in furthering our understanding both of the nature of gas around the Galactic center and of the abundance gradient of the Galaxy.

Metallicities of 4 blue supergiants near the Galactic centre

High resolution optical spectra of four blue supergiants (HD148422 B0.5 Ib; HD178487 B0.5 Ib; HD179407 B1 Ib, HD163522 B1 Ib) which lie within 4.5 kpc of the Galactic centre are presented. Careful differential LTE model atmosphere analyses are used to quantify the differences in photospheric metal abundances between these stars and MK spectral standards in the solar neighborhood. A detailed non-LTE model atmosphere analysis of one star (HD163522) confirms that the LTE differential abundances should be reliable, provided we use a comparison star with similar atmospheric parameters.

One-step synthesis of ZnO nanosheets: a blue-white fluorophore

Zinc oxide is synthesised at low temperature (80A degrees C) in nanosheet geometry using a substrate-free, single-step, wet-chemical method and is found to act as a blue-white fluorophore. Investigation by atomic force microscopy, electron microscopy, and X-ray diffraction confirms zinc oxide material of nanosheet morphology where the individual nanosheets are polycrystalline in nature with the crystalline structure being of wurtzite character. Raman spectroscopy indicates the presence of various defects, while photoluminescence measurements show intense green (centre wavelength approximately 515 nm) blue (approximately 450 nm), and less dominant red (approximately 640 nm) emissions due to a variety of vacancy and interstitial defects, mostly associated with surfaces or grain boundaries. The resulting colour coordinate on the CIE-1931 standard is (0.23, 0.33), demonstrating potential for use as a blue-white fluorescent coating in conjunction with ultraviolet emitting LEDs. Although the defects are often treated as draw-backs of ZnO, here we demonstrate useful broadband visible fluorescence properties in as-prepared ZnO. 

Reactive dye adsorption onto a novel mesoporous carbon

A new mesoporous carbon (MCSG60) was developed using an inexpensive commercial mesoporous silica gel as a template and sucrose as the carbon source. The surface area, porosity and density of the carbon were determined. The material possesses a high specific surface area and pore volume accessible for most typical aqueous pollutants. The adsorbent material was tested in a batch dye adsorption system. The behaviour of three reactive dyes adsorbed onto MCSG60 was evaluated (Naphthol Blue Black, NBB; Reactive Black 5, RB5; and Remazol Brilliant Blue R, RBBR). The maximum adsorption capacities obtained for the dyes were: 270. mg/g for NBB; 270. mg/g for RB5; and 280. mg/g for RBBR. Kinetic studies indicated that the adsorption process onto the mesoporous carbon was rapid and that equilibrium was reached in less than 1. h for all the dye systems investigated. Further batch experiments showed MCSG60 successfully adsorbed the dyes over a wide pH range and at low adsorbate concentration. The adsorption potential of MCSG60 for dye removal was further evaluated using a fixed-bed adsorption column. © 2013 Elsevier B.V.

In vivo safety of trypan blue use in vitreoretinal surgery

Purpose: The purpose of this study was to evaluate "in vivo" safety of trypan blue (TB) in patients undergoing TB-assisted internal limiting membrane or epiretinal membrane peeling. Methods: Prospective study including 21 patients (21 eyes) with full-thickness macular hole and/or epiretinal membrane undergoing TB-assisted internal limiting membrane/epiretinal membrane peeling. Main outcome measures included distance visual acuity, near visual acuity, amplitude of P50 and N95 of the pattern electroretinogram, and fundus autofluorescence; these were assessed preoperatively, at 6 months (n = 21) and 12 months (n = 10) postoperatively. Results: There was a statistically significant improvement in distance visual acuity, near visual acuity, P50, and N95 amplitude at 6 months and 12 months postoperatively. The mean logarithm of the minimum angle of resolution distance visual acuity and near visual acuity improved from baseline by 0.31 (SD 0.37) and 0.17 (SD 0.31) at 6 months, respectively, and by 0.4 (SD 0.25) and 0.35 (SD 0.28) at 12 months, respectively. The mean P50 and N95 component amplitudes improved by 28% compared with baseline at 6 months (P50 0.4 [SD 0.8]; N95 0.53 [SD 1.07]) and by 63% at 12 months (P50 0.9 [0.85]; N95 1.04 [1.34]). Autofluorescence did not demonstrate damage to the retinal pigment epithelium attributable to TB. Conclusion: No deleterious effects of TB were observed in this study. Copyright © 2011 Lippincott Williams &Wilkins.

Food of the Blue

An episode of BBC Radio 4's detective series 'Baldi'. Paolo Baldi finds himself in a world of superstar academics, but why are their bloodless corpses littering the college? And what is that thing they drink to rejuvenate the venerable institution?

Nile blue-based nano-sized pH sensors for simultaneous far-red and near-infrared live bioimaging

Diblock copolymer vesicles are tagged with pH-responsive Nile Blue-based labels and used as a new type of pH-responsive colorimetric/fluorescent biosensor for far-red and near-infrared imaging of live cells. The diblock copolymer vesicles described herein are based on poly(2-(methacryloyloxy)ethyl phosphorylcholine-block-2-(diisopropylamino)ethyl methacrylate) [PMPC-PDPA]: the biomimetic PMPC block is known to facilitate rapid cell uptake for a wide range of cell lines, while the PDPA block constitutes the pH-responsive component that enables facile vesicle self-assembly in aqueous solution. These biocompatible vesicles can be utilized to detect interstitial hypoxic/acidic regions in a tumor model via a pH-dependent colorimetric shift. In addition, they are also useful for selective intracellular staining of lysosomes and early endosomes via subtle changes in fluorescence emission. Such nanoparticles combine efficient cellular uptake with a pH-responsive Nile Blue dye label to produce a highly versatile dual capability probe. This is in marked contrast to small molecule dyes, which are usually poorly uptaken by cells, frequently exhibit cytotoxicity, and are characterized by intracellular distributions invariably dictated by their hydrophilic/hydrophobic balance.

Overcoming the Scalability Challenges of Epidemic Simulations on Blue Waters

Modeling dynamical systems represents an important application class covering a wide range of disciplines including but not limited to biology, chemistry, finance, national security, and health care. Such applications typically involve large-scale, irregular graph processing, which makes them difficult to scale due to the evolutionary nature of their workload, irregular communication and load imbalance. EpiSimdemics is such an application simulating epidemic diffusion in extremely large and realistic social contact networks. It implements a graph-based system that captures dynamics among co-evolving entities. This paper presents an implementation of EpiSimdemics in Charm++ that enables future research by social, biological and computational scientists at unprecedented data and system scales. We present new methods for application-specific processing of graph data and demonstrate the effectiveness of these methods on a Cray XE6, specifically NCSA's Blue Waters system.