200 research outputs found

    Imaging of membrane concentration polarization by NaCl using 23Na nuclear magnetic resonance

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    Forward osmosis (FO) and reverse osmosis (RO) membrane processes differ in their driving forces: osmotic pressure versus hydraulic pressure. Concentration polarization (CP) can adversely affect both performance and lifetime in such membrane systems. In order to mitigate against CP, the extent and severity of it need to be predicted more accurately through advanced online monitoring methodologies. Whilst a variety of monitoring techniques have been used to study the CP mechanism, there is still a pressing need to develop and apply non-invasive, in situ techniques able to produce quantitative, spatially resolved measurements of heterogeneous solute concentration in, and adjacent to, the membrane assembly as caused by the CP mechanism. To this end, 23Na magnetic resonance imaging (MRI) is used to image the sodium ion concentration within, and near to, both FO and RO composite membranes for the first time; this is also coupled with 1H MRI mapping of the corresponding water distribution. As such, it is possible to directly image salt accumulation due to CP processes during desalination. This was consistent with literature expectations and serves to confirm the suitability of 23Na MRI as a novel non-invasive technique for CP studies

    Variation in particulate C : N : P stoichiometry across the Lake Erie watershed from tributaries to its outflow

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    © 2017 The Authors Limnology and Oceanography published by Wiley Periodicals, Inc. on behalf of Association for the Sciences of Limnology and Oceanography Human activities can cause large alterations in biogeochemical cycles of key nutrients such as carbon (C), nitrogen (N), and phosphorus (P). However, relatively little is known about how these changes alter the proportional fluxes of these elements across ecosystem boundaries from rivers to lakes. Here, we examined environmental factors influencing spatial and temporal variation in particulate C : N : P ratios across the Lake Erie watershed from its tributaries to its outflow. Throughout the study, particulate nutrient ratios ranged widely (C : N 2.0–25.8, C : P 32–530, N : P 3.7–122.9), but mean values were generally lower than previous estimates from different aquatic environments. Particulate C : N ratios varied the least across all environments, but C : P and N : P ratios increased between tributaries and coastal areas and throughout the growing season in coastal environments. These ratios also differed temporally in offshore waters as particulate C : P and N : P were higher in the spring and summer and lower in the fall and winter. Particulate C : P ratios also increased between the western/central and eastern basins indicating differential nutrient processing across the lake. These stoichiometric changes were associated with unique environmental factors among ecosystems as tributary stoichiometry was related to terrestrial land use and land cover, coastal ratios were a product of mixing between riverine and offshore waters, and offshore patterns were influenced by differences in temperature and particulate nutrient loading among basins. Overall, by studying changes in particulate C : N : P ratios across the Lake Erie watershed, our study demonstrates the power of using mass balance principles to study nutrient transformations along the aquatic continuum

    The N2K Consortium. II. A Transiting Hot Saturn Around HD 149026 With a Large Dense Core

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    Doppler measurements from Subaru and Keck have revealed radial velocity variations in the V=8.15, G0IV star HD 149026 consistent with a Saturn-Mass planet in a 2.8766 day orbit. Photometric observations at Fairborn Observatory have detected three complete transit events with depths of 0.003 mag at the predicted times of conjunction. HD 149026 is now the second brightest star with a transiting extrasolar planet. The mass of the star, based on interpolation of stellar evolutionary models, is 1.3 +/- 0.1 solar masses; together with the Doppler amplitude, K=43.3 m s^-1, we derive a planet mass Msin(i)=0.36 Mjup, and orbital radius of 0.042 AU. HD 149026 is chromospherically inactive and metal-rich with spectroscopically derived [Fe/H]=+0.36, Teff=6147 K, log g=4.26 and vsin(i)=6.0 km s^-1. Based on Teff and the stellar luminosity of 2.72 Lsun, we derive a stellar radius of 1.45 Rsun. Modeling of the three photometric transits provides an orbital inclination of 85.3 +/- 1.0 degrees and (including the uncertainty in the stellar radius) a planet radius of 0.725 +/- 0.05 Rjup. Models for this planet mass and radius suggest the presence of a ~67 Mearth core composed of elements heavier than hydrogen and helium. This substantial planet core would be difficult to construct by gravitational instability.Comment: 25 pages, 5 figures, accepted by the Astrophysical Journa

    The DEEP Groth Strip Survey VI. Spectroscopic, Variability, and X-ray Detection of AGN

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    We identify active galactic nuclei (AGN) in the Groth-Westphal Survey Strip (GSS) using the independent and complementary selection techniques of optical spectroscopy and photometric variability. We discuss the X-ray properties of these AGN using Chandra/XMM data for this region. From a sample of 576 galaxies with high quality spectra we identify 31 galaxies with AGN signatures. Seven of these have broad emission lines (Type 1 AGNs). We also identify 26 galaxies displaying nuclear variability in HST WFPC2 images of the GSS separated by ~7 years. The primary overlap of the two selected AGN samples is the set of broad-line AGNs, of which 80% appear as variable. Only a few narrow-line AGNs approach the variability threshold. The broad-line AGNs have an average redshift of z~1.1 while the other spectroscopic AGNs have redshifts closer to the mean of the general galaxy population (z~0.7). Eighty percent of the identified broad-line AGNs are detected in X-rays and these are among the most luminous X-ray sources in the GSS. Only one narrow-line AGN is X-ray detected. Of the variable nuclei galaxies within the X-ray survey, 27% are X-ray detected. We find that 1.9+/-0.6% of GSS galaxies to V=24 are broad-line AGNs, 1.4+/-0.5% are narrow-line AGNs, and 4.5+/-1.4% contain variable nuclei. The fraction of spectroscopically identified BLAGNs and NLAGNs at z~1 reveals a marginally significant increase of 1.3+/-0.9% when compared to the local population.Comment: 29 pages, 8 figures, accepted for publication in ApJ

    Pore-scale analysis of formation damage in Bentheimer sandstone with in-situ NMR and micro-computed tomography experiments

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    We investigated fines movement through sandstone in-situ at the micrometre pore scale and studied the associated pore-scale mechanisms leading to formation damage. We used two in-situ techniques to accomplish this, namely nuclear magnetic resonance T2 relaxation time (NMR) measurements (of pore size distributions) and high resolution x-ray micro-computed tomography (μCT; at high resolutions of (0.89 μm)3 and (3.4 μm)3). The μCT images showed the precise 3D location of the fines particles in the plug and demonstrated that initially pore throats are plugged, followed by filling of adjacent pore bodies by solid particles. These measurements in combination with traditionally used (indirect) permeability and production curve measurements and ex-situ SEM imaging enabled us to propose a new mechanistic pore-scale plugging model; furthermore we demonstrated that the amount of fines trapped decayed rapidly with core depth. We conclude that it is feasible to analyse formation damage in-situ by a combination of NMR and μCT measurements

    The Ninth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-III Baryon Oscillation Spectroscopic Survey

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    The Sloan Digital Sky Survey III (SDSS-III) presents the first spectroscopic data from the Baryon Oscillation Spectroscopic Survey (BOSS). This ninth data release (DR9) of the SDSS project includes 535,995 new galaxy spectra (median z=0.52), 102,100 new quasar spectra (median z=2.32), and 90,897 new stellar spectra, along with the data presented in previous data releases. These spectra were obtained with the new BOSS spectrograph and were taken between 2009 December and 2011 July. In addition, the stellar parameters pipeline, which determines radial velocities, surface temperatures, surface gravities, and metallicities of stars, has been updated and refined with improvements in temperature estimates for stars with T_eff<5000 K and in metallicity estimates for stars with [Fe/H]>-0.5. DR9 includes new stellar parameters for all stars presented in DR8, including stars from SDSS-I and II, as well as those observed as part of the SDSS-III Sloan Extension for Galactic Understanding and Exploration-2 (SEGUE-2). The astrometry error introduced in the DR8 imaging catalogs has been corrected in the DR9 data products. The next data release for SDSS-III will be in Summer 2013, which will present the first data from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) along with another year of data from BOSS, followed by the final SDSS-III data release in December 2014.Comment: 9 figures; 2 tables. Submitted to ApJS. DR9 is available at http://www.sdss3.org/dr

    The Eighth Data Release of the Sloan Digital Sky Survey: First Data from SDSS-III

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    The Sloan Digital Sky Survey (SDSS) started a new phase in August 2008, with new instrumentation and new surveys focused on Galactic structure and chemical evolution, measurements of the baryon oscillation feature in the clustering of galaxies and the quasar Ly alpha forest, and a radial velocity search for planets around ~8000 stars. This paper describes the first data release of SDSS-III (and the eighth counting from the beginning of the SDSS). The release includes five-band imaging of roughly 5200 deg^2 in the Southern Galactic Cap, bringing the total footprint of the SDSS imaging to 14,555 deg^2, or over a third of the Celestial Sphere. All the imaging data have been reprocessed with an improved sky-subtraction algorithm and a final, self-consistent photometric recalibration and flat-field determination. This release also includes all data from the second phase of the Sloan Extension for Galactic Understanding and Evolution (SEGUE-2), consisting of spectroscopy of approximately 118,000 stars at both high and low Galactic latitudes. All the more than half a million stellar spectra obtained with the SDSS spectrograph have been reprocessed through an improved stellar parameters pipeline, which has better determination of metallicity for high metallicity stars.Comment: Astrophysical Journal Supplements, in press (minor updates from submitted version

    PUF60 variants cause a syndrome of ID, short stature, microcephaly, coloboma, craniofacial, cardiac, renal and spinal features.

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    PUF60 encodes a nucleic acid-binding protein, a component of multimeric complexes regulating RNA splicing and transcription. In 2013, patients with microdeletions of chromosome 8q24.3 including PUF60 were found to have developmental delay, microcephaly, craniofacial, renal and cardiac defects. Very similar phenotypes have been described in six patients with variants in PUF60, suggesting that it underlies the syndrome. We report 12 additional patients with PUF60 variants who were ascertained using exome sequencing: six through the Deciphering Developmental Disorders Study and six through similar projects. Detailed phenotypic analysis of all patients was undertaken. All 12 patients had de novo heterozygous PUF60 variants on exome analysis, each confirmed by Sanger sequencing: four frameshift variants resulting in premature stop codons, three missense variants that clustered within the RNA recognition motif of PUF60 and five essential splice-site (ESS) variant. Analysis of cDNA from a fibroblast cell line derived from one of the patients with an ESS variants revealed aberrant splicing. The consistent feature was developmental delay and most patients had short stature. The phenotypic variability was striking; however, we observed similarities including spinal segmentation anomalies, congenital heart disease, ocular colobomata, hand anomalies and (in two patients) unilateral renal agenesis/horseshoe kidney. Characteristic facial features included micrognathia, a thin upper lip and long philtrum, narrow almond-shaped palpebral fissures, synophrys, flared eyebrows and facial hypertrichosis. Heterozygote loss-of-function variants in PUF60 cause a phenotype comprising growth/developmental delay and craniofacial, cardiac, renal, ocular and spinal anomalies, adding to disorders of human development resulting from aberrant RNA processing/spliceosomal function

    Delineating the GRIN1 phenotypic spectrum: a distinct genetic NMDA receptor encephalopathy

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    Objective:To determine the phenotypic spectrum caused by mutations in GRIN1 encoding the NMDA receptor subunit GluN1 and to investigate their underlying functional pathophysiology.Methods:We collected molecular and clinical data from several diagnostic and research cohorts. Functional consequences of GRIN1 mutations were investigated in Xenopus laevis oocytes.Results:We identified heterozygous de novo GRIN1 mutations in 14 individuals and reviewed the phenotypes of all 9 previously reported patients. These 23 individuals presented with a distinct phenotype of profound developmental delay, severe intellectual disability with absent speech, muscular hypotonia, hyperkinetic movement disorder, oculogyric crises, cortical blindness, generalized cerebral atrophy, and epilepsy. Mutations cluster within transmembrane segments and result in loss of channel function of varying severity with a dominant-negative effect. In addition, we describe 2 homozygous GRIN1 mutations (1 missense, 1 truncation), each segregating with severe neurodevelopmental phenotypes in consanguineous families.Conclusions:De novo GRIN1 mutations are associated with severe intellectual disability with cortical visual impairment as well as oculomotor and movement disorders being discriminating phenotypic features. Loss of NMDA receptor function appears to be the underlying disease mechanism. The identification of both heterozygous and homozygous mutations blurs the borders of dominant and recessive inheritance of GRIN1-associated disorders.Johannes R. Lemke (32EP30_136042/1) and Peter De Jonghe (G.A.136.11.N and FWO/ESF-ECRP) received financial support within the EuroEPINOMICS-RES network (www.euroepinomics.org) within the Eurocores framework of the European Science Foundation (ESF). Saskia Biskup and Henrike Heyne received financial support from the German Federal Ministry for Education and Research (BMBF IonNeurONet: 01 GM1105A and FKZ: 01EO1501). Katia Hardies is a PhD fellow of the Institute for Science and Technology (IWT) Flanders. Ingo Helbig was supported by intramural funds of the University of Kiel, by a grant from the German Research Foundation (HE5415/3-1) within the EuroEPINOMICS framework of the European Science Foundation, and additional grants of the German Research Foundation (DFG, HE5415/5-1, HE 5415/6-1), German Ministry for Education and Research (01DH12033, MAR 10/012), and grant by the German chapter of the International League against Epilepsy (DGfE). The project also received infrastructural support through the Institute of Clinical Molecular Biology in Kiel, supported in part by DFG Cluster of Excellence "Inflammation at Interfaces" and "Future Ocean." The project was also supported by the popgen 2.0 network (P2N) through a grant from the German Ministry for Education and Research (01EY1103) and by the International Coordination Action (ICA) grant G0E8614N. Christel Depienne, Caroline Nava, and Delphine Heron received financial support for exome analyses by the Centre National de Genotypage (CNG, Evry, France)
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