Quantification and Characterization of Aluminum Distributions in Commercial Beta and Mordenite Zeolites by Cobalt Exchange

The aluminum distribution throughout the zeolite framework determines the structural, ion-exchange and catalytic properties of the zeolite. Several methods have been proposed to control the Al distribution, but in order to accurately assess these methods a procedure is needed to quantify Al distribution in various zeolite frameworks. Co2+ ions exchange onto the zeolite framework at Al pairs, and atomic absorbance spectroscopy (AAS) can be used to quantify the number of exchanged Co2+ ions and, in turn, the overall number of Al pairs. Each framework exhibits differences in pore size and channel configuration which affect the equilibrium conditions needed for saturation of all paired Al sites with Co2+ ions. In order to achieve saturation of the Co2+ ions, a reproducible exchange procedure must be developed for each framework of interest. Commercial beta (BEA) and mordenite (MOR) zeolites were subjected to liquid-phase cobalt ion exchange with varying exchange solution molarity, temperature, number of repetitions and time of exchange. The zeolites were then washed and treated in an oxidizing environment at high temperatures before undergoing AAS analysis to determine Co2+ concentration and diffuse reflectance UV-Vis spectroscopy (DRUV-VIS) to ensure only bare Co2+ ions were present. The BEA framework was found to achieve saturation at the following conditions: 0.50 M Co(NO3)2 exchange solution, ambient temperature, 1 repetition and 12 hour exchange time. The exchange procedure for MOR zeolites requires a 0.05 M Co(NO3)2 solution, ambient temperature, 24 hour exchange time and 1 repetition. These procedures will aid in the creation of an accurate catalog of the Al distribution in various commercially available BEA and MOR zeolites, as well as aiding in further synthesis studies to control the Al distribution in BEA and MOR zeolites

Daily cycle in oxygen consumption by the sea anemone Nematostella vectensis Stephenson

© The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Biology Open (2016): 1-4, doi:10.1242/bio.013474.In bilaterian animals, the circadian clock is intimately involved in regulating energetic metabolism. Although cnidarians exhibit diel behavioral rhythms including cycles in locomotor activity, tentacle extension and spawning, daily cycles in cnidarian metabolism have not been described. To explore a possible circadian metabolic cycle, we maintained the anemone Nematostella vectensis in a 12 h light/dark cycle, a reversed light cycle, or in constant darkness. Oxygen consumption rates were measured at intervals using an optical oxygen meter. Respiration rates responded to entrainment with higher rates during light periods. During a second experiment with higher temporal resolution, respiration rates peaked late in the light period. The diel pattern could be detected after six days in constant darkness. Together, our results suggest that respiration rates in Nematostella exhibit a daily cycle that may be under circadian control and that the cycle in respiration rate is not driven by the previously described nocturnal increase in locomotor activity in this species.Funding was provided by the US–Israel Binational Science Foundation [Grant 201187]. I.T.J. was supported by the WHOI Summer Student Fellow program, which is partially funded by the National Science Foundation Research Experience for Undergraduates program. A.M.R. was supported by National Institutes of Heath [R15GM114740]

Kinematics and Metallicity of M31 Red Giants: The Giant Southern Stream and Discovery of a Second Cold Component at R = 20 kpc

We present spectroscopic observations of red giant branch (RGB) stars in the Andromeda spiral galaxy (M31), acquired with the DEIMOS instrument on the Keck II 10-m telescope. The three fields targeted in this study are in the M31 spheroid, outer disk, and giant southern stream. In this paper, we focus on the kinematics and chemical composition of RGB stars in the stream field located at a projected distance of R = 20 kpc from M31's center. A mix of stellar populations is found in this field. M31 RGB stars are isolated from Milky Way dwarf star contaminants using a variety of spectral and photometric diagnostics. The radial velocity distribution of RGB stars displays a clear bimodality -- a primary peak centered at v = -513 km/s and a secondary one at v = -417 km/s -- along with an underlying broad component that is presumably representative of the smooth spheroid of M31. Both peaks are found to be dynamically cold with intrinsic velocity dispersions of sigma(v) = 16 km/s. The mean metallicity and metallicity dispersion of stars in the two peaks is also found to be similar: [Fe/H] = -0.45 and sigma([Fe/H]) = 0.2. The observed velocity of the primary peak is consistent with that predicted by dynamical models for the stream, but there is no obvious explanation for the secondary peak. The nature of the secondary cold population is unclear: it may represent: (1) tidal debris from a satellite merger event that is superimposed on, but unrelated to, the giant southern stream; (2) a wrapped around component of the giant southern stream; (3) a warp or overdensity in M31's disk at R > 50 kpc (this component is well above the outward extrapolation of the smooth exponential disk brightness profile).Comment: 32 pages, 13 figures, 1 table. Accepted for publication in Ap

Ultraviolet radiation significantly enhances the molecular response to dispersant and sweet crude oil exposure in Nematostella vectensis

Author Posting. © The Author(s), 2018. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Marine Environmental Research 134 (2018): 96-108, doi:10.1016/j.marenvres.2018.01.002.Estuarine organisms are subjected to combinations of anthropogenic and natural stressors, which together can reduce an organisms' ability to respond to either stress or can potentiate or synergize the cellular impacts for individual stressors. Nematostella vectensis (starlet sea anemone) is a useful model for investigating novel and evolutionarily conserved cellular and molecular responses to environmental stress. Using RNA-seq, we assessed global changes in gene expression in Nematostella in response to dispersant and/or sweet crude oil exposure alone or combined with ultraviolet radiation (UV). A total of 110 transcripts were differentially expressed by dispersant and/or crude oil exposure, primarily dominated by the down-regulation of 74 unique transcripts in the dispersant treatment. In contrast, UV exposure alone or combined with dispersant and/or oil resulted in the differential expression of 1133 transcripts, of which 436 were shared between all four treatment combinations. Most significant was the differential expression of 531 transcripts unique to one or more of the combined UV/chemical exposures. Main categories of genes affected by one or more of the treatments included enzymes involved in xenobiotic metabolism and transport, DNA repair enzymes, and general stress response genes conserved among vertebrates and invertebrates. However, the most interesting observation was the induction of several transcripts indicating de novo synthesis of mycosporine-like amino acids and other novel cellular antioxidants. Together, our data suggest that the toxicity of oil and/or dispersant and the complexity of the molecular response are significantly enhanced by UV exposure, which may co-occur for shallow water species like Nematostella.This material is based upon work supported by the National Science Foundation under Grant No. MCB1057152 (MJJ), MCB1057354 (AMT) and DEB1545539 (AMR)

Deep Photometry in a Remote M31 Major Axis Field Near G1

We present photometry from Hubble Space Telescope (HST)/Wide Field Planetary Camera 2 parallel imagery of a remote M31 field at a projected distance of about 34 kpc from the nucleus near the SW major axis. This field is near the globular cluster G1, and near one of the candidate tidal plumes identified by Ferguson et al. (2002). The F606W (V) and F814W (I) images were obtained in parallel with Space Telescope Imaging Spectrograph spectroscopy of G1 (GO-9099) and total 7.11 hours of integration time -- the deepest HST field in the outer disk of M31 to date, reaching to V ~ 28. The color-magnitude diagram of the field shows a clearly-defined red clump at V = 25.25 and a red giant branch consistent with [Fe/H] ~ -0.7. The lack of a blue horizontal branch contrasts with other M31 halo fields, the Andromeda dwarf spheroidals, and with the nearby globular cluster G1. Comparing the observed luminosity function to the Padova models, we find that at least some of the stellar population must be younger than 6 - 8 Gyr. The outermost detected neutral hydrogen gas disk of M31 lies only 2 kpc in projection from our field. The finding that some giants in the field have radial velocities close to that of the neutral hydrogen gas (Reitzel, Guhathakurta, & Rich 2003) leads us to conclude that our field samples the old, low-surface-brightness disk rather than the true Population II spheroid.Comment: 15 pages, 3 figures. accepted for publication in the A

A tidally distorted dwarf galaxy near NGC 4449

NGC 4449 is a nearby Magellanic irregular starburst galaxy with a B-band absolute magnitude of -18 and a prominent, massive, intermediate-age nucleus at a distance from Earth of 3.8 megaparsecs. It is wreathed in an extraordinary neutral hydrogen (H I) complex, which includes rings, shells and a counter-rotating core, spanning 90 kiloparsecs. NGC 4449 is relatively isolated, although an interaction with its nearest known companion-the galaxy DDO 125, some 40 kpc to the south-has been proposed as being responsible for the complexity of its HI structure. Here we report the presence of a dwarf galaxy companion to NGC 4449, namely NGC 4449B. This companion has a V-band absolute magnitude of -13.4 and a half-light radius of 2.7 kpc, with a full extent of around 8 kpc. It is in a transient stage of tidal disruption, similar to that of the Sagittarius dwarf near the Milky Way. NGC 4449B exhibits a striking S-shaped morphology that has been predicted for disrupting galaxies but has hitherto been seen only in a dissolving globular cluster. We also detect an additional arc or disk ripple embedded in a two-component stellar halo, including a component extending twice as far as previously known, to about 20 kpc from the galaxy's centre.Comment: Published in Nature, February 9, 2012. Nature, 482, 192-194 Published article available at http://www.nature.com/nature/journal/v482/n7384//full/nature10837.htm

Modulation of COUP-TF Expression in a Cnidarian by Ectopic Wnt Signalling and Allorecognition

COUP transcription factors are required for the regulation of gene expression underlying development, differentiation, and homeostasis. They have an evolutionarily conserved function, being a known marker for neurogenesis from cnidarians to vertebrates. A homologue of this gene was shown previously to be a neuronal and nematocyte differentiation marker in Hydra. However, COUP-TFs had not previously been studied in a colonial cnidarian.We cloned a COUP-TF homologue from the colonial marine cnidarian Hydractinia echinata. Expression of the gene was analysed during normal development, allorecognition events and ectopic Wnt activation, using in situ hybridisation and quantitative PCR. During normal Hydractinia development, the gene was first expressed in post-gastrula stages. It was undetectable in larvae, and its mRNA was present again in putative differentiating neurons and nematocytes in post-metamorphic stages. Global activation of canonical Wnt signalling in adult animals resulted in the upregulation of COUP-TF. We also monitored a strong COUP-TF upregulation in stolons undergoing allogeneic interactions. COUP-TF mRNA was most concentrated in the tissues that contacted allogeneic, non-self tissues, and decreased in a gradient away from the contact area. Interestingly, the gene was transiently upregulated during initial contact of self stolons, but dissipated rapidly following self recognition, while in non-self contacts high expression levels were maintained.We conclude that COUP-TF is likely involved in neuronal/nematocyte differentiation in a variety of contexts. This has now been shown to include allorecognition, where COUP-TF is thought to have been co-opted to mediate allorejection by recruiting stinging cells that are the effectors of cytotoxic rejection of allogeneic tissue. Our findings that Wnt activation upregulates COUP-TF expression suggests that Wnts' role in neuronal differentiation could be mediated through COUP-TF