2,689 research outputs found
New method for the deposition of nickel oxide in porous scaffolds for electrodes in solid oxide fuel cells and electrolyzers
A simple chemical bath deposition is used to coat a complex porous ceramic scaffold with a conformal nickel layer. The resulting composite is used as a Solid Oxide Fuel Cell electrode and its electrochemical response is measured in humidified hydrogen. X-Ray tomography is used to determine microstructural parameters of the uncoated and Ni-coated porous structure, among other, the surface area to total volume, the radial pore size and size of the necks between pores
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Deducing signaling pathways from parallel actions of arsenite and antimonite in human epidermal keratinocytes.
Inorganic arsenic oxides have been identified as carcinogens in several human tissues, including epidermis. Due to the chemical similarity between trivalent inorganic arsenic (arsenite) and antimony (antimonite), we hypothesized that common intracellular targets lead to similarities in cellular responses. Indeed, transcriptional and proteomic profiling revealed remarkable similarities in differentially expressed genes and proteins resulting from exposure of cultured human epidermal keratinocytes to arsenite and antimonite in contrast to comparisons of arsenite with other metal compounds. These data were analyzed to predict upstream regulators and affected signaling pathways following arsenite and antimonite treatments. A majority of the top findings in each category were identical after treatment with either compound. Inspection of the predicted upstream regulators led to previously unsuspected roles for oncostatin M, corticosteroids and ephrins in mediating cellular response. The influence of these predicted mediators was then experimentally verified. Together with predictions of transcription factor effects more generally, the analysis has led to model signaling networks largely accounting for arsenite and antimonite action. The striking parallels between responses to arsenite and antimonite indicate the skin carcinogenic risk of exposure to antimonite merits close scrutiny
Rapid grain growth in post-AGB disc systems from far-infrared and sub-millimetre photometry
The timescales on which astronomical dust grows remain poorly understood,
with important consequences for our understanding of processes like
circumstellar disk evolution and planet formation.A number of post-asymptotic
giant branch stars are found to host optically thick, dust- and gas-rich
circumstellar discs in Keplerian orbits. These discs exhibit evidence of dust
evolution, similar to protoplanetary discs; however since post-AGB discs have
substantially shorter lifetimes than protoplanetary discs they may provide new
insights on the grain-growth process. We examine a sample of post-AGB stars
with discs to determine the FIR and sub-mm spectral index by homogeneously
fitting a sample of data from \textit{Herschel}, the SMA and the literature. We
find that grain growth to at least hundreds of micrometres is ubiquitous in
these systems, and that the distribution of spectral indices is more similar to
that of protoplanetary discs than debris discs. No correlation is found with
the mid-infrared colours of the discs, implying that grain growth occurs
independently of the disc structure in post-AGB discs. We infer that grain
growth to mm sizes must occur on timescales yr, perhaps by
orders of magnitude, as the lifetimes of these discs are expected to be
~yr and all objects have converged to the same state. This
growth timescale is short compared to the results of models for protoplanetary
discs including fragmentation, and may provide new constraints on the physics
of grain growth.Comment: 13 pages, 7 figures. Accepted for publication in MNRA
The Non-thermal Radio Jet Toward the NGC 2264 Star Formation Region
We report sensitive VLA 3.6 cm radio observations toward the head of the Cone
nebula in NGC 2264, made in 2006. The purpose of these observations was to
study a non-thermal radio jet recently discovered, that appears to emanate from
the head of the Cone nebula. The jet is highly polarized, with well-defined
knots, and one-sided. The comparison of our images with 1995 archive data
indicates no evidence of proper motions nor polarization changes. We find
reliable flux density variations in only one knot, which we tentatively
identify as the core of a quasar or radio galaxy. An extragalactic location
seems to be the best explanation for this jet.Comment: 12 pages, 5 figure
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Non-Coding RNA Sequencing of Equine Endometrium During Maternal Recognition of Pregnancy.
Maternal recognition of pregnancy (MRP) in the mare is not well defined. In a non-pregnant mare, prostaglandin F2α (PGF) is released on day 14 post-ovulation (PO) to cause luteal regression, resulting in loss of progesterone production. Equine MRP occurs prior to day 14 to halt PGF production. Studies have failed to identify a gene candidate for MRP, so attention has turned to small, non-coding RNAs. The objective of this study was to evaluate small RNA (<200 nucleotides) content in endometrium during MRP. Mares were used in a cross-over design with each having a pregnant and non-mated cycle. Each mare was randomly assigned to collection day 11 or 13 PO (n = 3/day) and endometrial biopsies were obtained. Total RNA was isolated and sequencing libraries were prepared using a small RNA library preparation kit and sequenced on a HiSeq 2000. EquCab3 was used as the reference genome and DESeq2 was used for statistical analysis. On day 11, 419 ncRNAs, representing miRNA, snRNA, snoRNA, scaRNA, and vaultRNA, were different between pregnancy statuses, but none on day 13. Equine endometrial ncRNAs with unknown structure and function were also identified. This study is the first to describe ncRNA transcriptome in equine endometrium. Identifying targets of these ncRNAs could lead to determining MRP
Validación de un nuevo método de preconcentración y medición de mercurio en sedimentos utilizando materiales sol-gel dopados con extractantes sulfurados
El mercurio es un metal pesado altamente tóxico presente en el ambiente por causas naturales o
antropogénicas. El mercurio contenido en los cuerpos receptores de agua tiende a precipitarse y acumularse
en los sedimentos. Por lo tanto, las mediciones de mercurio en sedimentos representan un buen indicativo de
la calidad del ecosistema.
En este trabajo se presentan las diferentes etapas involucradas en el desarrollo de un nuevo método de
separación, preconcentración y medición de mercurio en sedimentos con contenidos naturales de este
elemento. La separación y preconcentración se realizó mediante el uso de nuevos materiales sorbentes
preparados a través del proceso sol-gel utilizando CYANEX 471X (sulfuro de triisobutilfosfina) y CYANEX 301
(ácido bis (2,4,4-trimetilpentil) ditiofosfínico) como extractantes de mercurio. Se describe la optimización de la
etapa de acoplamiento de los materiales empacados en columna, utilizando un sistema automatizado de
inyección de flujo, para conectarla en línea con un espectrómetro de absorción atómica donde se realizó la
medición de mercurio por generación de vapor frío. Como parte importante en el desarrollo de un nuevo
método analítico, se encuentra su validación, la cual es materia de este trabajo. Por lo tanto, una vez
optimizado, el método fue validado evaluando los siguientes parámetros: robustez, intervalo lineal y de
trabajo, límite de detección y de cuantificación, selectividad, exactitud (repetibilidad y veracidad) e
incertidumbre. El método fue aplicado para la medición de mercurio en un sedimento de presa con
contenidos naturales de este analito. Los resultados se compararon con los obtenidos mediante
espectrometría de masas con plasma inductivamente acoplado (ICP-MS) y espectrometría de fluorescencia
atómica con generación de vapor frío (CV-AFS
Hispanic Immigration to the United States
This chapter presents some of the exceptional characteristics of recent Hispanic immigration to the United States. In 2005, there were nearly 40 million Hispanic immigrants and descendants of Hispanic immigrants living in the U.S. The assimilation experience of this large cultural group does not seem to be following the path past immigrants to the U.S. followed. Most third generation Hispanics in the U.S. still find themselves with income and education levels below the U.S. averages. Most forecasts predict that about 60 million Hispanics and Hispanic-Americans will be living in the U.S. by 2030
A massive cluster of Red Supergiants at the base of the Scutum-Crux arm
We report on the unprecedented Red Supergiant (RSG) population of a massive
young cluster, located at the base of the Scutum-Crux Galactic arm. We identify
candidate cluster RSGs based on {\it 2MASS} photometry and medium resolution
spectroscopy. With follow-up high-resolution spectroscopy, we use CO-bandhead
equivalent width and high-precision radial velocity measurements to identify a
core grouping of 26 physically-associated RSGs -- the largest such cluster
known to-date. Using the stars' velocity dispersion, and their inferred
luminosities in conjuction with evolutionary models, we argue that the cluster
has an initial mass of 40,000\msun, and is therefore among the most
massive in the galaxy. Further, the cluster is only a few hundred parsecs away
from the cluster of 14 RSGs recently reported by Figer et al (2006). These two
RSG clusters represent 20% of all known RSGs in the Galaxy, and now offer the
unique opportunity to study the pre-supernova evolution of massive stars, and
the Blue- to Red-Supergiant ratio at uniform metallicity. We use GLIMPSE,
MIPSGAL and MAGPIS survey data to identify several objects in the field of the
larger cluster which seem to be indicative of recent region-wide starburst
activity at the point where the Scutum-Crux arm intercepts the Galactic bulge.
Future abundance studies of these clusters will therefore permit the study of
the chemical evolution and metallicity gradient of the Galaxy in the region
where the disk meets the bulge.Comment: 49 pages, 22 figures. Accepted for publication in ApJ. Version with
hi-res figures can be found at http://www.cis.rit.edu/~bxdpci/RSGC2.pd
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