The Relationship between Mg ii Broad Emission and Quasar Inclination Angle

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Conor Wildy

2017-11-01

Full Text Available Several observed spectral properties of quasars are believed to be influenced by quasar orientation. In this investigation we examine the effect of orientation on the Mg ii line located at 2,798 Å in a sample of 36 radio-loud quasars, with orientation angles having been obtained in a previous study using radio observations. We find no significant relationship between orientation angle and either Mg ii line full-width at half-maximum or equivalent width. The lack of correlation with inclination angle contradicts previous studies which also use radio data as a proxy for inclination angle and suggests the Mg ii emission region does not occupy a disk-like geometry. The lack of correlation with Mg ii equivalent width, however, is reported in at least one previous study. Although the significance is not very strong (86%, there is a possible negative relationship between inclination angle and Fe ii strength which, if true, could explain the Fe ii anti-correlation with [O iii] strength associated with Eigenvector 1. Interestingly, there are objects having almost edge-on inclinations while still exhibiting broad lines. This could be explained by a torus which is either clumpy (allowing sight lines to the central engine or mis-aligned with the accretion disk.

The Relationship between Mg ii Broad Emission and Quasar Inclination Angle

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Wildy, Conor; Czerny, Bozena, E-mail: wildy@cft.edu.pl [Center for Theoretical Physics, Polish Academy of Sciences, Warsaw (Poland)

2017-11-14

Several observed spectral properties of quasars are believed to be influenced by quasar orientation. In this investigation we examine the effect of orientation on the Mg ii line located at 2,798 Å in a sample of 36 radio-loud quasars, with orientation angles having been obtained in a previous study using radio observations. We find no significant relationship between orientation angle and either Mg ii line full-width at half-maximum or equivalent width. The lack of correlation with inclination angle contradicts previous studies which also use radio data as a proxy for inclination angle and suggests the Mg ii emission region does not occupy a disk-like geometry. The lack of correlation with Mg ii equivalent width, however, is reported in at least one previous study. Although the significance is not very strong (86%), there is a possible negative relationship between inclination angle and Fe ii strength which, if true, could explain the Fe ii anti-correlation with [O iii] strength associated with Eigenvector 1. Interestingly, there are objects having almost edge-on inclinations while still exhibiting broad lines. This could be explained by a torus which is either clumpy (allowing sight lines to the central engine) or mis-aligned with the accretion disk.

MAGIICAT I. THE Mg II ABSORBER-GALAXY CATALOG

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Nielsen, Nikole M.; Churchill, Christopher W. [New Mexico State University, Las Cruces, NM 88003 (United States); Kacprzak, Glenn G.; Murphy, Michael T., E-mail: nnielsen@nmsu.edu [Swinburne University of Technology, Victoria 3122 (Australia)

2013-10-20

We describe the Mg II Absorber-Galaxy Catalog, MAGIICAT, a compilation of 182 spectroscopically identified intermediate redshift (0.07 ≤ z ≤ 1.1) galaxies with measurements of Mg II λλ2796, 2803 absorption from their circumgalactic medium within projected distances of 200 kpc from background quasars. In this work, we present 'isolated' galaxies, which are defined as having no spectroscopically identified galaxy within a projected distance of 100 kpc and a line of sight velocity separation of 500 km s{sup –1}. We standardized all galaxy properties to the ΛCDM cosmology and galaxy luminosities, absolute magnitudes, and rest-frame colors to the B- and K-band on the AB system. We present galaxy properties and rest-frame Mg II equivalent width, W{sub r} (2796), versus galaxy redshift. The well-known anti-correlation between W{sub r} (2796) and quasar-galaxy impact parameter, D, is significant to the 8σ level. The mean color of MAGIICAT galaxies is consistent with an Sbc galaxy for all redshifts. We also present B- and K-band luminosity functions for different W{sub r} (2796) and redshift subsamples: 'weak absorbing' [W{sub r} (2796) < 0.3 Å], 'strong absorbing' [W{sub r} (2796) ≥ 0.3 Å], low redshift (z < (z)), and high redshift (z ≥ (z)), where (z) = 0.359 is the median galaxy redshift. Rest-frame color B – K correlates with M{sub K} at the 8σ level for the whole sample but is driven by the strong absorbing, high-redshift subsample (6σ). Using M{sub K} as a proxy for stellar mass and examining the luminosity functions, we infer that in lower stellar mass galaxies, Mg II absorption is preferentially detected in blue galaxies and the absorption is more likely to be weak.

Spectroscopic and thermal degradation behavior of Mg(II), Ca(II), Ba(II) and Sr(II) complexes with paracetamol drug

OpenAIRE

Moamen S. Refat; Gehad G. Mohamed; Mohamed Y. El-Sayed; Hamada M.A. Killa; Hammad Fetooh

2017-01-01

Complexes of Mg(II), Ca(II), Ba(II) and Sr(II) with paracetamol drug were synthesized and characterized by elemental analysis, conductivity, UV–Vis, IR, and 1H NMR spectroscopy and thermal analysis, as well as screened for antimicrobial activity. The IR spectral data suggested that the ligand behaves as paracetamol behaves as a neutral bidentate ligand coordinated to the metal ions via the lone pair of electrons of nitrogen and carbonyl-O atoms of the amide group. From the microanalytical dat...

Removal of Ca(II) and Mg(II) from potassium chromate solution on Amberlite IRC 748 synthetic resin by ion exchange

International Nuclear Information System (INIS)

Yu Zhihui; Qi Tao; Qu Jingkui; Wang Lina; Chu Jinglong

2009-01-01

Experimental measurements have been made on the batch ion exchange of Ca(II) and Mg(II) from potassium chromate solution using cation exchanger of Amberlite IRC 748 as K + form. The ion exchange behavior of two alkaline-earth metals on the resin, depending on contact time, pH, temperature and resin dosage was studied. The adsorption isotherms were described by means of the Langmuir and Freundlich isotherms. For Ca(II) ion, the Langmuir model represented the adsorption process better than the Freundlich model. The maximum ion exchange capacity was found to be 47.21 mg g -1 for Ca(II) and 27.70 mg g -1 for Mg(II). The kinetic data were tested using Lagergren-first-order and pseudo-second-order kinetic models. Kinetic data correlated well with the pseudo-second-order kinetic model, indicating that the chemical adsorption was the rate-limiting step. Various thermodynamic parameters such as Gibbs free energy (ΔG o ), enthalpy (ΔH o ) and entropy (ΔS o ) were also calculated. These parameters showed that the ion exchange of Ca(II) and Mg(II) from potassium chromate solution was feasible, spontaneous and endothermic process in nature. The activation energy of ion-exchange (E a ) was determined as 12.34 kJ mol -1 for Ca(II) and 9.865 kJ mol -1 for Mg(II) according to the Arrhenius equation.

MAGIICAT II. GENERAL CHARACTERISTICS OF THE Mg II ABSORBING CIRCUMGALACTIC MEDIUM

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Nielsen, Nikole M.; Churchill, Christopher W. [New Mexico State University, Las Cruces, NM 88003 (United States); Kacprzak, Glenn G., E-mail: nnielsen@nmsu.edu, E-mail: cwc@nmsu.edu, E-mail: gkacprzak@astro.swin.edu.au [Swinburne University of Technology, Victoria 3122 (Australia)

2013-10-20

We examine the Mg II absorbing circumgalactic medium (CGM) for the 182 intermediate redshift (0.072 ≤ z ≤ 1.120) galaxies in the 'Mg II Absorber-Galaxy Catalog' (MAGIICAT). We parameterize the anti-correlation between equivalent width, W{sub r} (2796), and impact parameter, D, with a log-linear fit, and show that a power law poorly describes the data. We find that higher luminosity galaxies have larger W{sub r} (2796) at larger D (4.3σ). The covering fractions, f{sub c} , decrease with increasing D and W{sub r} (2796) detection threshold. Higher luminosity galaxies have larger f{sub c} ; no absorption is detected in lower luminosity galaxies beyond 100 kpc. Bluer and redder galaxies have similar f{sub c} for D < 100 kpc, but for D > 100 kpc, bluer galaxies have larger f{sub c} , as do higher redshift galaxies. The 'absorption radius', R(L) = R{sub *}(L/L*){sup β}, which we examine for four different W{sub r} (2796) detection thresholds, is more luminosity sensitive to the B-band than the K-band, more sensitive for redder galaxies than for bluer galaxies, and does not evolve with redshift for the K-band, but becomes more luminosity sensitive toward lower redshift for the B-band. These trends clearly indicate a more extended Mg II absorbing CGM around higher luminosity, bluer, and higher redshift galaxies. Several of our findings are in conflict with other works. We address these conflicts and discuss the implications of our results for the low-ionization, intermediate redshift CGM.

THE PITTSBURGH SLOAN DIGITAL SKY SURVEY Mg II QUASAR ABSORPTION-LINE SURVEY CATALOG

International Nuclear Information System (INIS)

Quider, Anna M.; Nestor, Daniel B.; Turnshek, David A.; Rao, Sandhya M.; Weyant, Anja N.; Monier, Eric M.; Busche, Joseph R.

2011-01-01

We present a catalog of intervening Mg II quasar absorption-line systems in the redshift interval 0.36 ≤ z ≤ 2.28. The catalog was built from Sloan Digital Sky Survey Data Release Four (SDSS DR4) quasar spectra. Currently, the catalog contains ∼17, 000 measured Mg II doublets. We also present data on the ∼44, 600 quasar spectra which were searched to construct the catalog, including redshift and magnitude information, continuum-normalized spectra, and corresponding arrays of redshift-dependent minimum rest equivalent widths detectable at our confidence threshold. The catalog is available online. A careful second search of 500 random spectra indicated that, for every 100 spectra searched, approximately one significant Mg II system was accidentally rejected. Current plans to expand the catalog beyond DR4 quasars are discussed. Many Mg II absorbers are known to be associated with galaxies. Therefore, the combination of large size and well understood statistics makes this catalog ideal for precision studies of the low-ionization and neutral gas regions associated with galaxies at low to moderate redshift. An analysis of the statistics of Mg II absorbers using this catalog will be presented in a subsequent paper.

Revisiting the incidence of Mg II absorbers along the blazar sightlines

Science.gov (United States)

Mishra, Sapna; Chand, Hum; Gopal-Krishna; Joshi, Ravi

2018-04-01

It is believed that the cool gas clouds traced by Mg II absorption, within a velocity offset of 5000 km/s from the background quasar, are associated with the quasar itself, whereas the absorbers seen at larger velocity offsets towards us are intervening systems and hence their existence is completely independent of the background quasar. Recent evidence by Bergeron et al. 2011 (hereafter BBM), however, seriously questions this canonical view, by showing that the number density of intervening Mg II absorbers along the sightlines towards 45 blazars is, on average, 2 times the expectation based on the Mg II absorption systems seen on the sightlines to normal QSOs. Given the serious implications of this finding, it becomes important to revisit this issue by enlarging the source sample and subjecting it to an independent analysis. Here, we first report our results based on a re-analysis of the spectroscopic data for the BBM sample; this has reproduced their factor 2 excess in dN/dz along blazar sightlines, vis-a-vis the normal QSOs. Next, we assemble a 6 times larger sample of blazar sightlines, albeit with lower SNR. Using this enlarged sample together with the BBM sample, our analysis shows that the dN/dz of Mg II absorbers statistically matches that known for normal QSO sightlines.

Synthesis of new electroactive polymers by ion-exchange replacement of Mg(II) by 2H+ or Zn(II) cations inside Mg(II) polyporphine film, with their subsequent electrochemical transformation to condensed-structure materials

International Nuclear Information System (INIS)

Konev, Dmitry V.; Devillers, Charles H.; Lizgina, Ksenia V.; Zyubina, Tatiana S.; Zyubin, Alexander S.; Maiorova- Valkova, Larisa A.; Vorotyntsev, Mikhail A.

2014-01-01

It has been demonstrated that the treatment of the magnesium polyporphine of type I, pMgP-I, by trifluoroacetic acid in acetonitrile may be used to replace initial central Mg(II) cations inside the monomeric macrocycle units by protons, to get a new electroactive polymer, “free-base polyporphine of type I”, pH 2 P-I. In its turn, these inserted protons may be replaced by Zn(II) cations via the film treatment with zinc acetate in organic solvent, to get another new electroactive polymer, “zinc polyporphine of type I”, pZnP-I. These changes of central ions inside monomer units manifest themselves by characteristic modifications of their electroactive properties as well as of UV–visible and IR spectra. Similar to the magnesium polyporphine of type I, pMgP-I, studied in our previous paper (Electrochim. Acta, 2010, 55, 6703) both new polymers are subject to an irreversible electrooxidative transformation into the corresponding polyporphines of type II, pH 2 P-II and pZnP-II. All these polyporphines of type II demonstrate a very broad range of their redox activity, without any potential interval of non-electroactivity. It means that they represent electroactive polymers with a zero-width band gap in the neutral state of the polymer and the Fermi level is located into a broad electronic band for a wide range of the positive and negative oxidation states. Expected molecular structures of all these polymers are discussed

Modeling the distribution of Mg II absorbers around galaxies using background galaxies and quasars

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Bordoloi, R.; Lilly, S. J. [Institute for Astronomy, ETH Zürich, Wolfgang-Pauli-Strasse 27, 8093 Zürich (Switzerland); Kacprzak, G. G. [Swinburne University of Technology, Victoria 3122 (Australia); Churchill, C. W., E-mail: rongmonb@phys.ethz.ch [New Mexico State University, Las Cruces, NM 88003 (United States)

2014-04-01

We present joint constraints on the distribution of Mg II absorption around high redshift galaxies obtained by combining two orthogonal probes, the integrated Mg II absorption seen in stacked background galaxy spectra and the distribution of parent galaxies of individual strong Mg II systems as seen in the spectra of background quasars. We present a suite of models that can be used to predict, for different two- and three-dimensional distributions, how the projected Mg II absorption will depend on a galaxy's apparent inclination, the impact parameter b and the azimuthal angle between the projected vector to the line of sight and the projected minor axis. In general, we find that variations in the absorption strength with azimuthal angles provide much stronger constraints on the intrinsic geometry of the Mg II absorption than the dependence on the inclination of the galaxies. In addition to the clear azimuthal dependence in the integrated Mg II absorption that we reported earlier in Bordoloi et al., we show that strong equivalent width Mg II absorbers (W{sub r} (2796) ≥ 0.3 Å) are also asymmetrically distributed in azimuth around their host galaxies: 72% of the absorbers in Kacprzak et al., and 100% of the close-in absorbers within 35 kpc of the center of their host galaxies, are located within 50° of the host galaxy's projected semi minor axis. It is shown that either composite models consisting of a simple bipolar component plus a spherical or disk component, or a single highly softened bipolar distribution, can well represent the azimuthal dependencies observed in both the stacked spectrum and quasar absorption-line data sets within 40 kpc. Simultaneously fitting both data sets, we find that in the composite model the bipolar cone has an opening angle of ∼100° (i.e., confined to within 50° of the disk axis) and contains about two-thirds of the total Mg II absorption in the system. The single softened cone model has an exponential fall off with

TRACING OUTFLOWS AND ACCRETION: A BIMODAL AZIMUTHAL DEPENDENCE OF Mg II ABSORPTION

International Nuclear Information System (INIS)

Kacprzak, Glenn G.; Churchill, Christopher W.; Nielsen, Nikole M.

2012-01-01

We report a bimodality in the azimuthal angle distribution of gas around galaxies as traced by Mg II absorption: halo gas prefers to exist near the projected galaxy major and minor axes. The bimodality is demonstrated by computing the mean azimuthal angle probability distribution function using 88 spectroscopically confirmed Mg II-absorption-selected galaxies [W r (2796) ≥ 0.1 Å] and 35 spectroscopically confirmed non-absorbing galaxies [W r (2796) r (2796) r (2796) distribution for gas along the major axis is likely skewed toward weaker Mg II absorption than for gas along the projected minor axis. These combined results are highly suggestive that the bimodality is driven by gas accreted along the galaxy major axis and outflowing along the galaxy minor axis. Adopting these assumptions, we find that the opening angle of outflows and inflows to be 100° and 40°, respectively. We find that the probability of detecting outflows is ∼60%, implying that winds are more commonly observed.

Unusual broad-line Mg II emitters among luminous galaxies in the baryon oscillation spectroscopic survey

International Nuclear Information System (INIS)

Roig, Benjamin; Blanton, Michael R.; Ross, Nicholas P.

2014-01-01

Many classes of active galactic nuclei (AGNs) have been observed and recorded since the discovery of Seyfert galaxies. In this paper, we examine the sample of luminous galaxies in the Baryon Oscillation Spectroscopic Survey. We find a potentially new observational class of AGNs, one with strong and broad Mg II λ2799 line emission, but very weak emission in other normal indicators of AGN activity, such as the broad-line Hα, Hβ, and the near-ultraviolet AGN continuum, leading to an extreme ratio of broad Hα/Mg II flux relative to normal quasars. Meanwhile, these objects' narrow-line flux ratios reveal AGN narrow-line regions with levels of activity consistent with the Mg II fluxes and in agreement with that of normal quasars. These AGN may represent an extreme case of the Baldwin effect, with very low continuum and high equivalent width relative to typical quasars, but their ratio of broad Mg II to broad Balmer emission remains very unusual. They may also be representative of a class of AGN where the central engine is observed indirectly with scattered light. These galaxies represent a small fraction of the total population of luminous galaxies (≅ 0.1%), but are more likely (about 3.5 times) to have AGN-like nuclear line emission properties than other luminous galaxies. Because Mg II is usually inaccessible for the population of nearby galaxies, there may exist a related population of broad-line Mg II emitters in the local universe which is currently classified as narrow-line emitters (Seyfert 2 galaxies) or low ionization nuclear emission-line regions.

On the lack of correlation between Mg II 2796, 2803 Å and Lyα emission in lensed star-forming galaxies

Energy Technology Data Exchange (ETDEWEB)

Rigby, J. R. [Astrophysics Science Division, Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Bayliss, M. B. [Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138 (United States); Gladders, M. D. [Department of Astronomy and Astrophysics, University of Chicago, 5640 S. Ellis Avenue, Chicago, IL 60637 (United States); Sharon, K. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Wuyts, E. [Max Plank Institute for Extraterrestrial Physics, Giessenbachstrasse 1, D-85748 Garching (Germany); Dahle, H. [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, NO-0315 Oslo (Norway)

2014-07-20

We examine the Mg II 2796, 2803 Å, Lyα, and nebular line emission in five bright star-forming galaxies at 1.66 < z < 1.91 that have been gravitationally lensed by foreground galaxy clusters. All five galaxies show prominent Mg II emission and absorption in a P Cygni profile. We find no correlation between the equivalent widths of Mg II and Lyα emission. The Mg II emission has a broader range of velocities than do the nebular emission line profiles; the Mg II emission is redshifted with respect to systemic by 100-200 km s{sup –1}. When present, Lyα is even more redshifted. The reddest components of Mg II and Lyα emission have tails to 500-600 km s{sup –1}, implying a strong outflow. The lack of correlation in the Mg II and Lyα equivalent widths, the differing velocity profiles, and the high ratios of Mg II to nebular line fluxes together suggest that the bulk of Mg II emission does not ultimately arise as nebular line emission, but may instead be reprocessed stellar continuum emission.

SWIFT/UVOT GRISM MONITORING OF NGC 5548 IN 2013: AN ATTEMPT AT Mg ii REVERBERATION MAPPING

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Cackett, E. M.; Troyer, J. [Department of Physics and Astronomy, Wayne State University, 666 W. Hancock St, Detroit, MI 48201 (United States); Gültekin, K. [Department of Astronomy, University of Michigan, 1085 S. University Ave, Ann Arbor, MI 48109 (United States); Bentz, M. C. [Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303 (United States); Fausnaugh, M. M.; Peterson, B. M. [Department of Astronomy, The Ohio State University, 140 West 18th Ave, Columbus, OH 43210 (United States); Vestergaard, M., E-mail: ecackett@wayne.edu [Dark Cosmology Centre, The Niels Bohr Institute, Juliane Maries Vej 30, DK-2100 Copenhagen Ø (Denmark)

2015-09-10

Reverberation-mapping-based scaling relations are often used to estimate the masses of black holes from single-epoch spectra of active galactic nuclei (AGNs). While the radius–luminosity relation that is the basis of these scaling relations is determined using reverberation mapping of the Hβ line in nearby AGNs, the scaling relations are often extended to use other broad emission lines, such as Mg ii, in order to get black hole masses at higher redshifts when Hβ is redshifted out of the optical waveband. However, there is no radius–luminosity relation determined directly from Mg ii. Here, we present an attempt to perform reverberation mapping using Mg ii in the well-studied nearby Seyfert 1 NGC 5548. We used Swift to obtain UV grism spectra of NGC 5548 once every two days from 2013 April to September. Concurrent photometric UV monitoring with Swift provides a well determined continuum light curve that shows strong variability. The Mg ii emission line, however, is not strongly correlated with the continuum variability, and there is no significant lag between the two. We discuss these results in the context of using Mg ii scaling relations to estimate high-redshift black hole masses.

NON-LTE INVERSIONS OF THE Mg ii h and k AND UV TRIPLET LINES

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De la Cruz Rodríguez, Jaime; Leenaarts, Jorrit [Institute for Solar Physics, Dept. of Astronomy, Stockholm University, AlbaNova University Centre, SE-106 91 Stockholm Sweden (Sweden); Ramos, Andrés Asensio [Instituto de Astrofísica de Canarias, E-38205, La Laguna, Tenerife (Spain)

2016-10-20

The Mg ii h and k lines are powerful diagnostics for studying the solar chromosphere. They have become particularly popular with the launch of the Interface Region Imaging Spectrograph ( IRIS ) satellite, and a number of studies that include these lines have lead to great progress in understanding chromospheric heating, in many cases thanks to the support from 3D MHD simulations. In this study, we utilize another approach to analyze observations: non-LTE inversions of the Mg ii h and k and UV triplet lines including the effects of partial redistribution. Our inversion code attempts to construct a model atmosphere that is compatible with the observed spectra. We have assessed the capabilities and limitations of the inversions using the FALC atmosphere and a snapshot from a 3D radiation-MHD simulation. We find that Mg ii h and k allow reconstructing a model atmosphere from the middle photosphere to the transition region. We have also explored the capabilities of a multi-line/multi-atom setup, including the Mg ii h and k, the Ca ii 854.2 nm, and the Fe i 630.25 lines to recover the full stratification of physical parameters, including the magnetic field vector, from the photosphere to the chromosphere. Finally, we present the first inversions of observed IRIS spectra from quiet-Sun, plage, and sunspot, with very promising results.

Measurements of Narrow Mg II Associated Absorption Doublets with ...

Indian Academy of Sciences (India)

2016-01-27

Jan 27, 2016 ... The measurement of the variations of absorption lines over time is a good method to study the physical conditions of absorbers. In this paper, we measure the variations of the line strength of 36 narrow Mg II2796, 2803 associated absorption doublets, which are imprinted on 31 quasar spectra with two ...

Mixed ligand complexes of alkaline earth metals: Part XII. Mg(II, Ca(II, Sr(II and Ba(II complexes with 5-chlorosalicylaldehyde and salicylaldehyde or hydroxyaromatic ketones

Directory of Open Access Journals (Sweden)

MITHLESH AGRAWAL

2002-04-01

Full Text Available The reactions of alkaline earth metal chlorides with 5-chlorosalicylaldehyde and salicylaldehyde, 2-hydroxyacetophenone or 2-hydroxypropiophenone have been carried out in 1 : 1 : 1 mole ratio and the mixed ligand complexes of the type MLL’(H2O2 (where M = Mg(II, Ca(II, Sr(II and Ba(II, HL = 5-chlorosalicylaldehyde and HL’ = salicylaldehyde, 2-hydroxyacetophenone or 2-hydroxypropiophenone have been isolated. These complexes were characterized by TLC, conductance measurements, IR and 1H-NMR spectra.

TRACING OUTFLOWS AND ACCRETION: A BIMODAL AZIMUTHAL DEPENDENCE OF Mg II ABSORPTION

Energy Technology Data Exchange (ETDEWEB)

Kacprzak, Glenn G. [Swinburne University of Technology, Victoria 3122 (Australia); Churchill, Christopher W.; Nielsen, Nikole M., E-mail: gkacprzak@astro.swin.edu.au [New Mexico State University, Las Cruces, NM 88003 (United States)

2012-11-20

We report a bimodality in the azimuthal angle distribution of gas around galaxies as traced by Mg II absorption: halo gas prefers to exist near the projected galaxy major and minor axes. The bimodality is demonstrated by computing the mean azimuthal angle probability distribution function using 88 spectroscopically confirmed Mg II-absorption-selected galaxies [W{sub r} (2796) {>=} 0.1 A] and 35 spectroscopically confirmed non-absorbing galaxies [W{sub r} (2796) < 0.1 A] imaged with Hubble Space Telescope and Sloan Digital Sky Survey. The azimuthal angle distribution for non-absorbers is flat, indicating no azimuthal preference for gas characterized by W{sub r} (2796) < 0.1 A. We find that blue star-forming galaxies clearly drive the bimodality while red passive galaxies may exhibit an excess along their major axis. These results are consistent with galaxy evolution scenarios where star-forming galaxies accrete new gas, forming new stars and producing winds, while red galaxies exist passively due to reduced gas reservoirs. We further compute an azimuthal angle dependent Mg II absorption covering fraction, which is enhanced by as much as 20%-30% along the major and minor axes. The W{sub r} (2796) distribution for gas along the major axis is likely skewed toward weaker Mg II absorption than for gas along the projected minor axis. These combined results are highly suggestive that the bimodality is driven by gas accreted along the galaxy major axis and outflowing along the galaxy minor axis. Adopting these assumptions, we find that the opening angle of outflows and inflows to be 100 Degree-Sign and 40 Degree-Sign , respectively. We find that the probability of detecting outflows is {approx}60%, implying that winds are more commonly observed.

Blue-wing enhancement of the chromospheric Mg II h and k lines in a solar flare

Science.gov (United States)

Tei, Akiko; Sakaue, Takahito; Okamoto, Takenori J.; Kawate, Tomoko; Heinzel, Petr; UeNo, Satoru; Asai, Ayumi; Ichimoto, Kiyoshi; Shibata, Kazunari

2018-05-01

We performed coordinated observations of AR 12205, which showed a C-class flare on 2014 November 11, with the Interface Region Imaging Spectrograph (IRIS) and the Domeless Solar Telescope (DST) at Hida Observatory. Using spectral data in the Si IV 1403 Å, C II 1335 Å, and Mg II h and k lines from IRIS and the Ca II K, Ca II 8542 Å, and Hα lines from DST, we investigated a moving flare kernel during the flare. In the Mg II h line, the leading edge of the flare kernel showed an intensity enhancement in the blue wing and a smaller intensity of the blue-side peak (h2v) than that of the red-side one (h2r). The blueshift lasted for 9-48 s with a typical speed of 10.1 ± 2.6 km s-1, which was followed by a high intensity and a large redshift with a speed of up to 51 km s-1 detected in the Mg II h line. The large redshift was a common property for all six lines, but the blueshift prior to it was found only in the Mg II lines. Cloud modeling of the Mg II h line suggests that the blue-wing enhancement with such a peak difference could have been caused by a chromospheric-temperature (cool) upflow. We discuss a scenario in which an upflow of cool plasma is lifted up by expanding hot plasma owing to the deep penetration of non-thermal electrons into the chromosphere. Furthermore, we found that the blueshift persisted without any subsequent redshift in the leading edge of the flare kernel during its decaying phase. The cause of such a long-lasting blueshift is also discussed.

A Parameter Study for Modeling Mg ii h and k Emission during Solar Flares

Energy Technology Data Exchange (ETDEWEB)

Rubio da Costa, Fatima [Department of Physics, Stanford University, Stanford, CA 94305 (United States); Kleint, Lucia, E-mail: frubio@stanford.edu [University of Applied Sciences and Arts Northwestern Switzerland, 5210, Windisch (Switzerland)

2017-06-20

Solar flares show highly unusual spectra in which the thermodynamic conditions of the solar atmosphere are encoded. Current models are unable to fully reproduce the spectroscopic flare observations, especially the single-peaked spectral profiles of the Mg ii h and k lines. We aim to understand the formation of the chromospheric and optically thick Mg ii h and k lines in flares through radiative transfer calculations. We take a flare atmosphere obtained from a simulation with the radiative hydrodynamic code RADYN as input for a radiative transfer modeling with the RH code. By iteratively changing this model atmosphere and varying thermodynamic parameters such as temperature, electron density, and velocity, we study their effects on the emergent intensity spectra. We reproduce the typical single-peaked Mg ii h and k flare spectral shape and approximate the intensity ratios to the subordinate Mg ii lines by increasing either densities, temperatures, or velocities at the line core formation height range. Additionally, by combining unresolved upflows and downflows up to ∼250 km s{sup −1} within one resolution element, we reproduce the widely broadened line wings. While we cannot unambiguously determine which mechanism dominates in flares, future modeling efforts should investigate unresolved components, additional heat dissipation, larger velocities, and higher densities and combine the analysis of multiple spectral lines.

The Associated Absorption Features in Quasar Spectra of the Sloan Digital Sky Survey. I. Mg II Absorption Doublets

Science.gov (United States)

Chen, Zhi-Fu; Huang, Wei-Rong; Pang, Ting-Ting; Huang, Hong-Yan; Pan, Da-Sheng; Yao, Min; Nong, Wei-Jing; Lu, Mei-Mei

2018-03-01

Using the SDSS spectra of quasars included in the DR7Q or DR12Q catalogs, we search for Mg II λλ2796, 2803 narrow absorption doublets in the spectra data around Mg II λ2798 emission lines. We obtain 17,316 Mg II doublets, within the redshift range of 0.3299 ≤ z abs ≤ 2.5663. We find that a velocity offset of υ r 6000 km s‑1. If associated Mg II absorbers are defined by υ r present at least one associated Mg II system with {W}{{r}}λ 2796≥slant 0.2 \\mathringA . The fraction of associated Mg II systems with high-velocity outflows correlates with the average luminosities of their central quasars, indicating a relationship between outflows and the quasar feedback power. The υ r distribution of the outflow Mg II absorbers is peaked at 1023 km s‑1, which is smaller than the corresponding value of the outflow C IV absorbers. The redshift number density evolution of absorbers (dn/dz) limited by υ r > ‑3000 km s‑1 differs from that of absorbers constrained by υ r > 2000 km s‑1. Absorbers limited by υ r > 2000 km s‑1 and higher values exhibit profiles similar to dn/dz. In addition, the dn/dz is smaller when absorbers are constrained with larger υ r . The distributions of equivalent widths, and the ratio of {W}rλ 2796/{W}rλ 2803, are the same for associated and intervening systems, and independent of quasar luminosity.

Precious metals in SDSS quasar spectra. II. Tracking the evolution of strong, 0.4 < z < 2.3 Mg II absorbers with thousands of systems

International Nuclear Information System (INIS)

Seyffert, Eduardo N.; Simcoe, Robert A.; Cooksey, Kathy L.; O'Meara, John M.; Kao, Melodie M.; Prochaska, J. Xavier

2013-01-01

We have performed an analysis of over 34,000 Mg II doublets at 0.36 < z < 2.29 in Sloan Digital Sky Survey (SDSS) Data Release 7 quasar spectra; the catalog, advanced data products, and tools for analysis are publicly available. The catalog was divided into 14 small redshift bins with roughly 2500 doublets in each and from Monte Carlo simulations, we estimate 50% completeness at rest equivalent width W r ≈ 0.8 Å. The equivalent width frequency distribution is described well by an exponential model at all redshifts, and the distribution becomes flatter with increasing redshift, i.e., there are more strong systems relative to weak ones. Direct comparison with previous SDSS Mg II surveys reveals that we recover at least 70% of the doublets in these other catalogs, in addition to detecting thousands of new systems. We discuss how these surveys came by their different results, which qualitatively agree but because of the very small uncertainties, differ by a statistically significant amount. The estimated physical cross section of Mg II-absorbing galaxy halos increased approximately threefold from z = 0.4 to z = 2.3, while the W r ≥ 1 Å absorber line density, dN MgII /dX, grew by roughly 45%. Finally, we explore the different evolution of various absorber populations—damped Lyα absorbers, Lyman limit systems, strong C IV absorbers, and strong and weaker Mg II systems—across cosmic time (0 < z < 6).

OBSERVATIONS OF Mg II ABSORPTION NEAR z ∼ 1 GALAXIES SELECTED FROM THE DEEP2 REDSHIFT SURVEY

International Nuclear Information System (INIS)

Lovegrove, Elizabeth; Simcoe, Robert A.

2011-01-01

We study the frequency of Mg II absorption in the outer halos of galaxies at z = 0.6-1.4 (with median z = 0.87), using new spectra obtained of 10 background quasars with galaxy impact parameters of b r = 0.15-1.0 A, though not all absorbers correlate with DEEP galaxies. We find five unique absorbers within Δv = 500 km s -1 and b r > 1.0 A, consistent with other samples of galaxy-selected Mg II systems. We speculate that Mg II systems with 0.3 r r are more likely to reflect the more recent star-forming history of their associated galaxies.

Calibration and Limitations of the Mg II Line-based Black Hole Masses

Science.gov (United States)

Woo, Jong-Hak; Le, Huynh Anh N.; Karouzos, Marios; Park, Dawoo; Park, Daeseong; Malkan, Matthew A.; Treu, Tommaso; Bennert, Vardha N.

2018-06-01

We present single-epoch black hole mass ({M}BH}) calibrations based on the rest-frame ultraviolet (UV) and optical measurements of Mg II 2798 Å and Hβ 4861 Å lines and the active galactic nucleus (AGN) continuum, using a sample of 52 moderate-luminosity AGNs at z ∼ 0.4 and z ∼ 0.6 with high-quality Keck spectra. We combine this sample with a large number of luminous AGNs from the Sloan Digital Sky Survey to increase the dynamic range for a better comparison of UV and optical velocity and luminosity measurements. With respect to the reference {M}BH} based on the line dispersion of Hβ and continuum luminosity at 5100 Å, we calibrate the UV and optical mass estimators by determining the best-fit values of the coefficients in the mass equation. By investigating whether the UV estimators show a systematic trend with Eddington ratio, FWHM of Hβ, Fe II strength, or UV/optical slope, we find no significant bias except for the slope. By fitting the systematic difference of Mg II-based and Hβ-based masses with the L 3000/L 5100 ratio, we provide a correction term as a function of the spectral index as ΔC = 0.24 (1 + α λ ) + 0.17, which can be added to the Mg II-based mass estimators if the spectral slope can be well determined. The derived UV mass estimators typically show >∼0.2 dex intrinsic scatter with respect to the Hβ-based {M}BH}, suggesting that the UV-based mass has an additional uncertainty of ∼0.2 dex, even if high-quality rest-frame UV spectra are available.

Comparison of Mg-based multilayers for solar He II radiation at 30.4 nm wavelength

Energy Technology Data Exchange (ETDEWEB)

Zhu Jingtao; Zhou Sika; Li Haochuan; Huang Qiushi; Wang Zhanshan; Le Guen, Karine; Hu, Min-Hui; Andre, Jean-Michel; Jonnard, Philippe

2010-07-10

Mg-based multilayers, including SiC/Mg, Co/Mg, B4C/Mg, and Si/Mg, are investigated for solar imaging and a He II calibration lamp at a 30.4 nm wavelength. These multilayers were fabricated by a magnetron sputtering method and characterized by x-ray reflection. The reflectivities of these multilayers were measured by synchrotron radiation. Near-normal-incidence reflectivities of Co/Mg and SiC/Mg multilayer mirrors are as high as 40.3% and 44.6%, respectively, while those of B4C/Mg and Si/Mg mirrors are too low for application. The measured results suggest that SiC/Mg, Co/Mg multilayers are promising for a 30.4 nm wavelength.

A First Comparison of Millimeter Continuum and Mg ii Ultraviolet Line Emission from the Solar Chromosphere

Energy Technology Data Exchange (ETDEWEB)

Bastian, T. S. [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States); Chintzoglou, G.; De Pontieu, B.; Schmit, D. [Lockheed Martin Solar and Astrophysics Lab, Org. A021S, Building 252, 3251 Hanover Street, Palo Alto, CA 94304 (United States); Shimojo, M. [National Astronomical Observatory of Japan, 2-21-1, Osawa, Mitaka, Tokyo 181-8588 (Japan); Leenaarts, J. [Institute for Solar Physics, Department of Astronomy, Stockholm University, AlbaNova University Centre, SE-106 91 Stockholm (Sweden); Loukitcheva, M., E-mail: tbastian@nrao.edu [Center For Solar-Terrestrial Research, New Jersey Institute of Technology, 323 Martin Luther King Boulevard, Newark, NJ 07102 (United States)

2017-08-20

We present joint observations of the Sun by the Atacama Large Millimeter/submillimeter Array (ALMA) and the Interface Region Imaging Spectrograph ( IRIS ). Both millimeter/submillimeter- λ continuum emission and ultraviolet (UV) line emission originate from the solar chromosphere and both have the potential to serve as powerful and complementary diagnostics of physical conditions in this enigmatic region of the solar atmosphere. The observations were made of a solar active region on 2015 December 18 as part of the ALMA science verification effort. A map of the Sun’s continuum emission was obtained by ALMA at a wavelength of 1.25 mm (239 GHz). A contemporaneous map was obtained by IRIS in the Mg ii h doublet line at 2803.5 Å. While a clear correlation between the 1.25 mm brightness temperature T{sub B} and the Mg ii h line radiation temperature T {sub rad} is observed, the slope is <1, perhaps as a result of the fact that these diagnostics are sensitive to different parts of the chromosphere and that the Mg ii h line source function includes a scattering component. There is a significant difference (35%) between the mean T{sub B} (1.25 mm) and mean T {sub rad} (Mg ii). Partitioning the maps into “sunspot,” “quiet areas,” and “plage regions” we find the relation between the IRIS Mg ii h line T {sub rad} and the ALMA T {sub B} region-dependent. We suggest this may be the result of regional dependences of the formation heights of the IRIS and ALMA diagnostics and/or the increased degree of coupling between the UV source function and the local gas temperature in the hotter, denser gas in plage regions.

A First Comparison of Millimeter Continuum and Mg ii Ultraviolet Line Emission from the Solar Chromosphere

International Nuclear Information System (INIS)

Bastian, T. S.; Chintzoglou, G.; De Pontieu, B.; Schmit, D.; Shimojo, M.; Leenaarts, J.; Loukitcheva, M.

2017-01-01

We present joint observations of the Sun by the Atacama Large Millimeter/submillimeter Array (ALMA) and the Interface Region Imaging Spectrograph ( IRIS ). Both millimeter/submillimeter- λ continuum emission and ultraviolet (UV) line emission originate from the solar chromosphere and both have the potential to serve as powerful and complementary diagnostics of physical conditions in this enigmatic region of the solar atmosphere. The observations were made of a solar active region on 2015 December 18 as part of the ALMA science verification effort. A map of the Sun’s continuum emission was obtained by ALMA at a wavelength of 1.25 mm (239 GHz). A contemporaneous map was obtained by IRIS in the Mg ii h doublet line at 2803.5 Å. While a clear correlation between the 1.25 mm brightness temperature T_B and the Mg ii h line radiation temperature T _r_a_d is observed, the slope is <1, perhaps as a result of the fact that these diagnostics are sensitive to different parts of the chromosphere and that the Mg ii h line source function includes a scattering component. There is a significant difference (35%) between the mean T_B (1.25 mm) and mean T _r_a_d (Mg ii). Partitioning the maps into “sunspot,” “quiet areas,” and “plage regions” we find the relation between the IRIS Mg ii h line T _r_a_d and the ALMA T _B region-dependent. We suggest this may be the result of regional dependences of the formation heights of the IRIS and ALMA diagnostics and/or the increased degree of coupling between the UV source function and the local gas temperature in the hotter, denser gas in plage regions.

MAGNETIC DIAGNOSTICS OF THE SOLAR CHROMOSPHERE WITH THE Mg II h–k LINES

Energy Technology Data Exchange (ETDEWEB)

Del Pino Alemán, T.; Casini, R. [High Altitude Observatory, National Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000 (United States); Manso Sainz, R. [Max-Planck-Institut für Sonnensystemforschung, Justus-von-Liebig-Weg 3, D-37077 Göttingen (Germany)

2016-10-20

We investigated the formation of the Mg ii h–k doublet in a weakly magnetized atmosphere (20–100 G) using a newly developed numerical code for polarized radiative transfer in a plane-parallel geometry, which implements a recent formulation of partially coherent scattering by polarized multi-term atoms in arbitrary magnetic-field regimes. Our results confirm the importance of partial redistribution effects in the formation of the Mg ii h and k lines, as pointed out by previous work in the non-magnetic case. We show that the presence of a magnetic field can produce measurable modifications of the broadband linear polarization even for relatively small field strengths (∼10 G), while the circular polarization remains well represented by the classical magnetograph formula. Both these results open an important new window for the weak-field diagnostics of the upper solar atmosphere.

THE FORMATION OF IRIS DIAGNOSTICS. II. THE FORMATION OF THE Mg II h and k LINES IN THE SOLAR ATMOSPHERE

Energy Technology Data Exchange (ETDEWEB)

Leenaarts, J.; Pereira, T. M. D.; Carlsson, M.; De Pontieu, B. [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway); Uitenbroek, H., E-mail: jorritl@astro.uio.no, E-mail: tiago.pereira@astro.uio.no, E-mail: mats.carlsson@astro.uio.no, E-mail: bdp@lmsal.com, E-mail: huitenbroek@nso.edu [NSO/Sacramento Peak P.O. Box 62 Sunspot, NM 88349-0062 (United States)

2013-08-01

NASA's Interface Region Imaging Spectrograph (IRIS) small explorer mission will study how the solar atmosphere is energized. IRIS contains an imaging spectrograph that covers the Mg II h and k lines as well as a slit-jaw imager centered at Mg II k. Understanding the observations requires forward modeling of Mg II h and k line formation from three-dimensional (3D) radiation-magnetohydrodynamic (RMHD) models. This paper is the second in a series where we undertake this modeling. We compute the vertically emergent h and k intensity from a snapshot of a dynamic 3D RMHD model of the solar atmosphere, and investigate which diagnostic information about the atmosphere is contained in the synthetic line profiles. We find that the Doppler shift of the central line depression correlates strongly with the vertical velocity at optical depth unity, which is typically located less than 200 km below the transition region (TR). By combining the Doppler shifts of the h and k lines we can retrieve the sign of the velocity gradient just below the TR. The intensity in the central line depression is anti-correlated with the formation height, especially in subfields of a few square Mm. This intensity could thus be used to measure the spatial variation of the height of the TR. The intensity in the line-core emission peaks correlates with the temperature at its formation height, especially for strong emission peaks. The peaks can thus be exploited as a temperature diagnostic. The wavelength difference between the blue and red peaks provides a diagnostic of the velocity gradients in the upper chromosphere. The intensity ratio of the blue and red peaks correlates strongly with the average velocity in the upper chromosphere. We conclude that the Mg II h and k lines are excellent probes of the very upper chromosphere just below the TR, a height regime that is impossible to probe with other spectral lines. They also provide decent temperature and velocity diagnostics of the middle

Activity of pyramidal I and II slip in Mg alloys as revealed by texture development

Science.gov (United States)

Zecevic, Miroslav; Beyerlein, Irene J.; Knezevic, Marko

2018-02-01

Due to the geometry of the hexagonal close-packed (HCP) lattice, there are two types of pyramidal slip modes: { 10 1 bar 1 } 〈 11 2 bar 3 bar 〉 or type I and { 1 bar 1 bar 22 } 〈 11 2 bar 3 〉 or type II in HCP crystalline materials. Here we use crystal plasticity to examine the importance of crystallographic slip by pyramidal type I and type II on texture evolution. The study is applied to an Mg-4%Li alloy. An elastic-plastic polycrystal model is employed to elucidate the reorientation tendencies of these two slip modes in rolling of a textured polycrystal. Comparisons with experimental texture measurements indicate that both pyramidal I and II type slip were active during rolling deformation, with pyramidal I being the dominant mode. A single-slip-mode analysis is used to identify the orientations that prefer pyramidal I vs. II type slip when acting alone in a crystal. The analysis applies not only to Mg-4%Li, but identifies the key texture components in HCP crystals that would help distinguish the activity of pyramidal I from pyramidal II slip in rolling deformation.

MgII Linear Polarization Measurements Using the MSFC Solar Ultraviolet Magnetograph

Science.gov (United States)

West, Edward; Cirtain, Jonathan; Kobayahsi, Ken; Davis, John; Gary, Allen; Adams, Mitzi

2011-01-01

This paper will describe the Marshall Space Flight Center's Solar Ultraviolet Magnetograph (SUMI) sounding rocket program, with emphasis on the polarization characteristics of the VUV optics and their spectral, spatial and polarization resolution. SUMI's first flight (7/30/2010) met all of its mission success criteria and this paper will describe the data that was acquired with emphasis on the MgII linear polarization measurements.

Black Hole Mass Estimation in Type 1 AGN: Hβ vs. Mg II Lines and the Role of Balmer Continuum

Energy Technology Data Exchange (ETDEWEB)

Kovačević-Dojčinović, Jelena [Astronomical Observatory, Belgrade (Serbia); Marčeta-Mandić, Sladjana; Popović, Luka Č., E-mail: sladjana@aob.rs [Astronomical Observatory, Belgrade (Serbia); Department of Astronomy, Faculty of Mathematics, University of Belgrade, Belgrade (Serbia)

2017-07-24

Here we investigate the Hβ and Mg II spectral line parameters used for the black hole mass (M{sub BH}) estimation for a sample of Type 1 Active Galactic Nuclei (AGN) spectra selected from the Sloan Digital Sky Survey (SDSS) database. We have analyzed and compared the virialization of the Hβ and Mg II emission lines, and found that the Hβ line is more confident virial estimator than Mg II. We have investigated the influence of the Balmer continuum emission to the M{sub BH} estimation from the UV parameters, and found that the Balmer continuum emission can contribute to the overestimation of the M{sub BH} on average for ~5% (up to 10%).

Simulating the Mg II NUV Spectra & C II Resonance Lines During Solar Flares

Science.gov (United States)

Kerr, Graham Stewart; Allred, Joel C.; Leenaarts, Jorrit; Butler, Elizabeth; Kowalski, Adam

2017-08-01

The solar chromosphere is the origin of the bulk of the enhanced radiative output during solar flares, and so comprehensive understanding of this region is important if we wish to understand energy transport in solar flares. It is only relatively recently, however, with the launch of IRIS that we have routine spectroscopic flarea observations of the chromsphere and transition region. Since several of the spectral lines observed by IRIS are optically thick, it is necessary to use forward modelling to extract the useful information that these lines carry about the flaring chromosphere and transition region. We present the results of modelling the formation properties Mg II resonance lines & subordinate lines, and the C II resonance lines during solar flares. We focus on understanding their relation to the physical strucutre of the flaring atmosphere, exploiting formation height differences to determine if we can extract information about gradients in the atmosphere. We show the effect of degrading the profiles to the resolution of the IRIS, and that the usual observational techniques used to identify the line centroid do a poor job in the early stages of the flare (partly due to multiple optically thick line components). Finally, we will tentatively comment on the effects that 3D radiation transfer may have on these lines.

MAGIICAT III. Interpreting self-similarity of the circumgalactic medium with virial mass using Mg II absorption

International Nuclear Information System (INIS)

Churchill, Christopher W.; Trujillo-Gomez, Sebastian; Nielsen, Nikole M.; Kacprzak, Glenn G.

2013-01-01

In Churchill et al., we used halo abundance matching applied to 182 galaxies in the Mg II Absorber-Galaxy Catalog (MAGIICAT) and showed that the mean Mg II λ2796 equivalent width follows a tight inverse-square power law, W r (2796)∝(D/R vir ) –2 , with projected location relative to the galaxy virial radius and that the Mg II absorption covering fraction is effectively invariant with galaxy virial mass, M h , over the range 10.7 ≤ log M h /M ☉ ≤ 13.9. In this work, we explore multivariate relationships between W r (2796), virial mass, impact parameter, virial radius, and the theoretical cooling radius that further elucidate self-similarity in the cool/warm (T = 10 4 -10 4.5 K) circumgalactic medium (CGM) with virial mass. We show that virial mass determines the extent and strength of the Mg II absorbing gas such that the mean W r (2796) increases with virial mass at fixed distance while decreasing with galactocentric distance for fixed virial mass. The majority of the absorbing gas resides within D ≅ 0.3 R vir , independent of both virial mass and minimum absorption threshold; inside this region, and perhaps also in the region 0.3 < D/R vir ≤ 1, the mean W r (2796) is independent of virial mass. Contrary to absorber-galaxy cross-correlation studies, we show there is no anti-correlation between W r (2796) and virial mass. We discuss how simulations and theory constrained by observations support self-similarity of the cool/warm CGM via the physics governing star formation, gas-phase metal enrichment, recycling efficiency of galactic scale winds, filament and merger accretion, and overdensity of local environment as a function of virial mass.

MAGIICAT III. Interpreting self-similarity of the circumgalactic medium with virial mass using Mg II absorption

Energy Technology Data Exchange (ETDEWEB)

Churchill, Christopher W.; Trujillo-Gomez, Sebastian; Nielsen, Nikole M. [New Mexico State University, Las Cruces, NM 88003 (United States); Kacprzak, Glenn G. [Swinburne University of Technology, Victoria 3122 (Australia)

2013-12-10

In Churchill et al., we used halo abundance matching applied to 182 galaxies in the Mg II Absorber-Galaxy Catalog (MAGIICAT) and showed that the mean Mg II λ2796 equivalent width follows a tight inverse-square power law, W{sub r} (2796)∝(D/R {sub vir}){sup –2}, with projected location relative to the galaxy virial radius and that the Mg II absorption covering fraction is effectively invariant with galaxy virial mass, M {sub h}, over the range 10.7 ≤ log M {sub h}/M {sub ☉} ≤ 13.9. In this work, we explore multivariate relationships between W{sub r} (2796), virial mass, impact parameter, virial radius, and the theoretical cooling radius that further elucidate self-similarity in the cool/warm (T = 10{sup 4}-10{sup 4.5} K) circumgalactic medium (CGM) with virial mass. We show that virial mass determines the extent and strength of the Mg II absorbing gas such that the mean W{sub r} (2796) increases with virial mass at fixed distance while decreasing with galactocentric distance for fixed virial mass. The majority of the absorbing gas resides within D ≅ 0.3 R {sub vir}, independent of both virial mass and minimum absorption threshold; inside this region, and perhaps also in the region 0.3 < D/R {sub vir} ≤ 1, the mean W{sub r} (2796) is independent of virial mass. Contrary to absorber-galaxy cross-correlation studies, we show there is no anti-correlation between W{sub r} (2796) and virial mass. We discuss how simulations and theory constrained by observations support self-similarity of the cool/warm CGM via the physics governing star formation, gas-phase metal enrichment, recycling efficiency of galactic scale winds, filament and merger accretion, and overdensity of local environment as a function of virial mass.

Comparison of Solar Fine Structure Observed Simultaneously in Lyα and Mg II h

Science.gov (United States)

Schmit, D.; Sukhorukov, A. V.; De Pontieu, B.; Leenaarts, J.; Bethge, C.; Winebarger, A.; Auchère, F.; Bando, T.; Ishikawa, R.; Kano, R.; Kobayashi, K.; Narukage, N.; Trujillo Bueno, J.

2017-10-01

The Chromospheric Lyman Alpha Spectropolarimeter (CLASP) observed the Sun in H I Lyα during a suborbital rocket flight on 2015 September 3. The Interface Region Imaging Telescope (IRIS) coordinated with the CLASP observations and recorded nearly simultaneous and co-spatial observations in the Mg II h and k lines. The Mg II h and Lyα lines are important transitions, energetically and diagnostically, in the chromosphere. The canonical solar atmosphere model predicts that these lines form in close proximity to each other and so we expect that the line profiles will exhibit similar variability. In this analysis, we present these coordinated observations and discuss how the two profiles compare over a region of quiet Sun at viewing angles that approach the limb. In addition to the observations, we synthesize both line profiles using a 3D radiation-MHD simulation. In the observations, we find that the peak width and the peak intensities are well correlated between the lines. For the simulation, we do not find the same relationship. We have attempted to mitigate the instrumental differences between IRIS and CLASP and to reproduce the instrumental factors in the synthetic profiles. The model indicates that formation heights of the lines differ in a somewhat regular fashion related to magnetic geometry. This variation explains to some degree the lack of correlation, observed and synthesized, between Mg II and Lyα. Our analysis will aid in the definition of future observatories that aim to link dynamics in the chromosphere and transition region.

Comparison of Solar Fine Structure Observed Simultaneously in Ly α and Mg ii h

Energy Technology Data Exchange (ETDEWEB)

Schmit, D. [Bay Area Environmental Research Institute, 625 2nd Street, Suite 209, Petaluma, CA 94952 (United States); Sukhorukov, A. V.; Leenaarts, J. [Institute for Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern NO-0315 Oslo (Norway); De Pontieu, B. [Lockheed Martin Solar and Astrophysics Laboratory, Building 252, 3176 Porter Drive, Palo Alto, CA 94304 (United States); Bethge, C.; Winebarger, A.; Kobayashi, K. [NASA Marshall Space Flight Center, ZP 13, Huntsville, AL 35812 (United States); Auchère, F. [Institut d’Astrophysique Spatiale, CNRS/Univ. Paris-Sud 11, Bâtiment 121, F-91405 Orsay (France); Bando, T.; Kano, R.; Narukage, N. [National Astronomical Observatory of Japan, National Institutes of Natural Sciences, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Ishikawa, R. [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Bueno, J. Trujillo [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain)

2017-10-01

The Chromospheric Lyman Alpha Spectropolarimeter (CLASP) observed the Sun in H i Ly α during a suborbital rocket flight on 2015 September 3. The Interface Region Imaging Telescope ( IRIS ) coordinated with the CLASP observations and recorded nearly simultaneous and co-spatial observations in the Mg ii h and k lines. The Mg ii h and Ly α lines are important transitions, energetically and diagnostically, in the chromosphere. The canonical solar atmosphere model predicts that these lines form in close proximity to each other and so we expect that the line profiles will exhibit similar variability. In this analysis, we present these coordinated observations and discuss how the two profiles compare over a region of quiet Sun at viewing angles that approach the limb. In addition to the observations, we synthesize both line profiles using a 3D radiation-MHD simulation. In the observations, we find that the peak width and the peak intensities are well correlated between the lines. For the simulation, we do not find the same relationship. We have attempted to mitigate the instrumental differences between IRIS and CLASP and to reproduce the instrumental factors in the synthetic profiles. The model indicates that formation heights of the lines differ in a somewhat regular fashion related to magnetic geometry. This variation explains to some degree the lack of correlation, observed and synthesized, between Mg ii and Ly α . Our analysis will aid in the definition of future observatories that aim to link dynamics in the chromosphere and transition region.

Electrochemistry of Zn(II)/Zn on Mg alloy from the N-butyl-N-methylpyrrolidinium dicyanamide ionic liquid

Energy Technology Data Exchange (ETDEWEB)

Deng, Ming-Jay, E-mail: martinez730523@yahoo.com.tw [National Synchrotron Radiation Research Center, Hsinchu, Taiwan (China); Lin, Pei-Chiung [Department of Chemistry, National Cheng Kung University, Tainan, Taiwan (China); Chang, Jeng-Kuei, E-mail: jkchang@ncu.edu.tw [Institute of Materials Science and Engineering, National Central University, Taoyuan, Taiwan (China); Chen, Jin-Ming; Lu, Kueih-Tzu [National Synchrotron Radiation Research Center, Hsinchu, Taiwan (China)

2011-07-01

Highlights: > Electrodeposition of Zn was successfully demonstrnated in the water- and air-stable BMP-DCA ionic liquid. While ZnCl{sub 2} is insoluble in the BMP-TFSI ionic liquid, it dissolves easily in the BMP-DCA. > Amperometric titration experiments indicated that Zn(II) probably complexed as [Zn(DCA){sub 3}]- with DCA- anion. > Chronoamperometric experiments showed that the electrodeposition of Zn on GC and Mg alloy substrates involved 3D-instantaneous nucleation/growth process. > A lower deposition rate would bring out a more uniform and compact Zn coating layer (which is also thicker) and, consequently, this coating revealed a protection capability for the Mg substrate against corrosion. - Abstract: Electrochemical reaction of Zn(II)/Zn on glassy carbon electrode(GC) and Mg alloy substrates was investigated in the room-temperature ionic liquid, N-butyl-N-methyl-pyrrolidinium dicyanamide (BMP-DCA) containing ZnCl{sub 2} at 323 K. Amperometric titration experiments suggest that Zn(II) reacted with DCA anions forming [Zn(DCA){sub 3}]{sup -} complex anion, which also could be reduced to Zn metal via a single-step electron transfer process. By chronoamperometric measurements, the electrodeposition of Zn on GC and Mg alloy substrates involved three-dimensional instantaneous nucleation under diffusion control at 323 K. The Zn deposits are also systematically characterized by the techniques of powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The Zn layer deposited at a lower current density on Mg alloy substrates was more compact and uniform when compared to that deposited at a higher current density; consequently, this coating revealed a protection capability for the Mg substrate against corrosion.

Self-consistent Non-LTE Model of Infrared Molecular Emissions and Oxygen Dayglows in the Mesosphere and Lower Thermosphere

Science.gov (United States)

Feofilov, Artem G.; Yankovsky, Valentine A.; Pesnell, William D.; Kutepov, Alexander A.; Goldberg, Richard A.; Mauilova, Rada O.

2007-01-01

We present the new version of the ALI-ARMS (for Accelerated Lambda Iterations for Atmospheric Radiation and Molecular Spectra) model. The model allows simultaneous self-consistent calculating the non-LTE populations of the electronic-vibrational levels of the O3 and O2 photolysis products and vibrational level populations of CO2, N2,O2, O3, H2O, CO and other molecules with detailed accounting for the variety of the electronic-vibrational, vibrational-vibrational and vibrational-translational energy exchange processes. The model was used as the reference one for modeling the O2 dayglows and infrared molecular emissions for self-consistent diagnostics of the multi-channel space observations of MLT in the SABER experiment It also allows reevaluating the thermalization efficiency of the absorbed solar ultraviolet energy and infrared radiative cooling/heating of MLT by detailed accounting of the electronic-vibrational relaxation of excited photolysis products via the complex chain of collisional energy conversion processes down to the vibrational energy of optically active trace gas molecules.

Mg II ABSORPTION CHARACTERISTICS OF A VOLUME-LIMITED SAMPLE OF GALAXIES AT z ∼ 0.1

International Nuclear Information System (INIS)

Barton, Elizabeth J.; Cooke, Jeff

2009-01-01

We present an initial survey of Mg II absorption characteristics in the halos of a carefully constructed, volume-limited subsample of galaxies embedded in the spectroscopic part of the Sloan Digital Sky Survey (SDSS). We observed quasars near sightlines to 20 low-redshift (z ∼ 0.1), luminous (M r + 5log h ≤-20.5) galaxies in SDSS DR4 and DR6 with the LRIS-B spectrograph on the Keck I telescope. The primary systematic criteria for the targeted galaxies are a redshift z ∼> 0.1 and the presence of an appropriate bright background quasar within a projected 75 h -1 kpc of its center, although we preferentially sample galaxies with lower impact parameters and slightly more star formation within this range. Of the observed systems, six exhibit strong (W eq (2796) ≥ 0.3 A) Mg II absorption at the galaxy's redshift, six systems have upper limits which preclude strong Mg II absorption, while the remaining observations rule out very strong (W eq (2796) ≥ 1-2 A) absorption. The absorbers fall at higher impact parameters than many non-absorber sightlines, indicating a covering fraction f c ∼ -1 kpc (f c ∼ 0.25). The data are consistent with a possible dependence of covering fraction and/or absorption halo size on the environment or star-forming properties of the central galaxy.

OH-asterisk (7-5) Meinel band dayglow and nightglow measured by the SME limb scanning near infrared spectrometer - Comparison of the observed seasonal variability with two-dimensional model simulations

Science.gov (United States)

Le Texier, H.; Solomon, S.; Thomas, R. J.; Garcia, R. R.

1989-01-01

Seasonal variations of the OH-asterisk (7-5) mesospheric hydroxyl emission at 1.89 microns observed by the SME near-IR spectrometer are compared with the theoretical predictions of a two-dimensional dynamical/chemical model. The good agreement found at low latitudes for both dayglow and nightglow provides support for the model assumption that breaking gravity waves induce seasonal and latitudinal variations in diffusion. The seasonal behavior of atomic hydrogen in the upper mesosphere (related to vertical transport) and/or uncertainties in the OH Meinel band parameters are proposed as possible explanations for the discrepancy noted between model and observational data for the middle latitudes.

Calculated Resonance Line Profiles of [Mg II], [C II], and [Si IV] in the Solar Atmosphere

Science.gov (United States)

Avrett, E.; Landi, E.; McKillop, S.

2013-12-01

NASA's Interface Region Imaging Spectrograph space mission, launched 2013 June 27, is intended to study the structure of the solar chromosphere and the transition region between the chromosphere and corona. The spectral lines to be observed include the Mg II k line at 2796.5 Å, the C II 1334.5 Å line, and the Si IV line at 1393.8 Å, which are formed in the middle chromosphere, the upper chromosphere, and the lower transition region, respectively. Here we calculate the profiles of these lines from four models of the solar atmosphere, intended to represent the faint and mean internetwork, a network lane, and bright network. We show how the profiles change from the center of the solar disk toward the limb of the Sun and in response to outflows and inflows. These results are intended to cover the range of expected quiet-Sun observations and assist in their interpretation. We expect that the observations will lead to improvements in the models, which can then be used to estimate the required non-radiative heating in the different regions.

Calculated resonance line profiles of [Mg II], [C II], and [Si IV] in the solar atmosphere

International Nuclear Information System (INIS)

Avrett, E.; McKillop, S.; Landi, E.

2013-01-01

NASA's Interface Region Imaging Spectrograph space mission, launched 2013 June 27, is intended to study the structure of the solar chromosphere and the transition region between the chromosphere and corona. The spectral lines to be observed include the Mg II k line at 2796.5 Å, the C II 1334.5 Å line, and the Si IV line at 1393.8 Å, which are formed in the middle chromosphere, the upper chromosphere, and the lower transition region, respectively. Here we calculate the profiles of these lines from four models of the solar atmosphere, intended to represent the faint and mean internetwork, a network lane, and bright network. We show how the profiles change from the center of the solar disk toward the limb of the Sun and in response to outflows and inflows. These results are intended to cover the range of expected quiet-Sun observations and assist in their interpretation. We expect that the observations will lead to improvements in the models, which can then be used to estimate the required non-radiative heating in the different regions.

THE H I MASS DENSITY IN GALACTIC HALOS, WINDS, AND COLD ACCRETION AS TRACED BY Mg II ABSORPTION

Energy Technology Data Exchange (ETDEWEB)

Kacprzak, Glenn G. [Swinburne University of Technology, Victoria 3122 (Australia); Churchill, Christopher W., E-mail: gkacprzak@astro.swin.edu.au, E-mail: cwc@nmsu.edu [New Mexico State University, Las Cruces, NM 88003 (United States)

2011-12-20

It is well established that Mg II absorption lines detected in background quasar spectra arise from gas structures associated with foreground galaxies. The degree to which galaxy evolution is driven by the gas cycling through halos is highly uncertain because their gas mass density is poorly constrained. Fitting the Mg II equivalent width (W) distribution with a Schechter function and applying the N(H I)-W correlation of Menard and Chelouche, we computed {Omega}(H I){sub MgII} {identical_to} {Omega}(H I){sub halo} = 1.41{sup +0.75}{sub -0.44} Multiplication-Sign 10{sup -4} for 0.4 {<=} z {<=} 1.4. We exclude damped Ly{alpha}'s (DLAs) from our calculations so that {Omega}(H I){sub halo} comprises accreting and/or outflowing halo gas not locked up in cold neutral clouds. We deduce that the cosmic H I gas mass density fraction in galactic halos traced by Mg II absorption is {Omega}(H I){sub halo}/{Omega}(H I){sub DLA} {approx_equal} 15% and {Omega}(H I){sub halo}/{Omega}{sub b} {approx_equal} 0.3%. Citing several lines of evidence, we propose that infall/accretion material is sampled by small W whereas outflow/winds are sampled by large W, and find that {Omega}(H I){sub infall} is consistent with {Omega}(H I){sub outflow} for bifurcation at W = 1.23{sup +0.15}{sub -0.28} Angstrom-Sign ; cold accretion would then comprise no more than {approx}7% of the total H I mass density. We discuss evidence that (1) the total H I mass cycling through halos remains fairly constant with cosmic time and that the accretion of H I gas sustains galaxy winds, and (2) evolution in the cosmic star formation rate depends primarily on the rate at which cool H I gas cycles through halos.

Large-scale correlations in gas traced by Mg II absorbers around low-mass galaxies

Science.gov (United States)

Kauffmann, Guinevere

2018-03-01

The physical origin of the large-scale conformity in the colours and specific star formation rates of isolated low-mass central galaxies and their neighbours on scales in excess of 1 Mpc is still under debate. One possible scenario is that gas is heated over large scales by feedback from active galactic nuclei (AGNs), leading to coherent modulation of cooling and star formation between well-separated galaxies. In this Letter, the metal line absorption catalogue of Zhu & Ménard is used to probe gas out to large projected radii around a sample of a million galaxies with stellar masses ˜1010M⊙ and photometric redshifts in the range 0.4 Survey imaging data. This galaxy sample covers an effective volume of 2.2 Gpc3. A statistically significant excess of Mg II absorbers is present around the red-low-mass galaxies compared to their blue counterparts out to projected radii of 10 Mpc. In addition, the equivalent width distribution function of Mg II absorbers around low-mass galaxies is shown to be strongly affected by the presence of a nearby (Rp < 2 Mpc) radio-loud AGNs out to projected radii of 5 Mpc.

The Wilson-Bappu effect of the MgII k line - dependence on stellar temperature, activity and metallicity

DEFF Research Database (Denmark)

Elgaroy, O.; Engvold, O.; Lund, Niels

1999-01-01

widths around the regression lines. The sample contains slowly rotating stars of different activity levels and is suitable for investigations of a possible relation between line width and stellar activity. A difference in behavior between dwarfs and giants (and supergiants) of spectral class K seems......The Wilson-Bappu effect is investigated using accurate absolute magnitudes of 65 stars obtained through early release of data from the Hipparcos satellite together with MgII k fine widths determined from high resolution spectra observed with the International Ultraviolet Explorer (IUE) observatory....... Stars of spectral classes F, G, K and M and luminosity classes I-V are represented in the sample. Wilson-Bappu relations for the Mg II k line for stars of different temperatures i.e. spectral classes are determined. The relation varies with spectral class and there is a significant scatter of the line...

THE SMOOTH Mg II GAS DISTRIBUTION THROUGH THE INTERSTELLAR/EXTRA-PLANAR/HALO INTERFACE

Energy Technology Data Exchange (ETDEWEB)

Kacprzak, Glenn G.; Cooke, Jeff; Ryan-Weber, Emma V. [Swinburne University of Technology, VIC 3122 (Australia); Churchill, Christopher W.; Nielsen, Nikole M., E-mail: gkacprzak@astro.swin.edu.au [New Mexico State University, Las Cruces, NM 88003 (United States)

2013-11-01

We report the first measurements of Mg II absorption systems associated with spectroscopically confirmed z ∼ 0.1 star-forming galaxies at projected distances of D < 6 kpc. We demonstrate that the data are consistent with the well-known anti-correlation between rest-frame Mg II equivalent width, W{sub r} (2796), and impact parameter, D, represented by a single log-linear relation derived by Nielsen et al. (MAGIICAT) that converges to ∼2 Å at D = 0 kpc. Incorporating MAGIICAT, we find that the halo gas covering fraction is unity below D ∼ 25 kpc. We also report that our D < 6 kpc absorbers are consistent with the W{sub r} (2796) distributions of the Milky Way interstellar medium (ISM) and ISM+halo. In addition, quasar sight lines of intermediate redshift galaxies with 6 < D < 25 kpc have an equivalent width distribution similar to that of the Milky Way halo, implying that beyond ∼6 kpc, quasar sight lines are likely probing halo gas and not the ISM. As inferred by the Milky Way and our new data, the gas profiles of galaxies can be fit by a single log-linear W{sub r} (2796)-D relation out to large scales across a variety of gas-phase conditions and is maintained through the halo/extra-planar/ISM interfaces, which is remarkable considering their kinematic complexity. These low-redshift, small impact parameter absorption systems are the first steps to bridge the gap between quasar absorption-line studies and H I observations of the circumgalactic medium.

AN INDEPENDENT MEASUREMENT OF THE INCIDENCE OF Mg II ABSORBERS ALONG GAMMA-RAY BURST SIGHT LINES: THE END OF THE MYSTERY?

International Nuclear Information System (INIS)

Cucchiara, A.; Prochaska, J. X.; Zhu, G.; Ménard, B.; Fynbo, J. P. U.; Fox, D. B.; Chen, H.-W.; Cooksey, K. L.; Cenko, S. B.; Bloom, J. S.; Perley, D.; Berger, E.; Chornock, R.; Tanvir, N. R.; D'Elia, V.; Lopez, S.; De Jaeger, T.

2013-01-01

In 2006, Prochter et al. reported a statistically significant enhancement of very strong Mg II absorption systems intervening the sight lines to gamma-ray bursts (GRBs) relative to the incidence of such absorption along quasar sight lines. This counterintuitive result has inspired a diverse set of astrophysical explanations (e.g., dust, gravitational lensing) but none of these has obviously resolved the puzzle. Using the largest set of GRB afterglow spectra available, we reexamine the purported enhancement. In an independent sample of GRB spectra with a survey path three times larger than Prochter et al., we measure the incidence per unit redshift of ≥1 Å rest-frame equivalent width Mg II absorbers at z ≈ 1 to be l(z) = 0.18 ± 0.06. This is fully consistent with current estimates for the incidence of such absorbers along quasar sight lines. Therefore, we do not confirm the original enhancement and suggest those results suffered from a statistical fluke. Signatures of the original result do remain in our full sample (l(z) shows an ≈1.5 enhancement over l(z) QSO ), but the statistical significance now lies at ≈90% c.l. Restricting our analysis to the subset of high-resolution spectra of GRB afterglows (which overlaps substantially with Prochter et al.), we still reproduce a statistically significant enhancement of Mg II absorption. The reason for this excess, if real, is still unclear since there is no connection between the rapid afterglow follow-up process with echelle (or echellette) spectrographs and the detectability of strong Mg II doublets. Only a larger sample of such high-resolution data will shed some light on this matter

Spectroscopic investigation of new water soluble Mn(II)(2) and Mg(II)(2) complexes for the substrate binding models of xylose/glucose isomerases.

Science.gov (United States)

Patra, Ayan; Bera, Manindranath

2014-01-30

In methanol, the reaction of stoichiometric amounts of Mn(OAc)(2)·4H(2)O and the ligand H(3)hpnbpda [H(3)hpnbpda=N,N'-bis(2-pyridylmethyl)-2-hydroxy-1,3-propanediamine-N,N'-diacetic acid] in the presence of NaOH, afforded a new water soluble dinuclear manganese(II) complex, [Mn2(hpnbpda)(μ-OAc)] (1). Similarly, the reaction of Mg(OAc)(2)·4H(2)O and the ligand H3hpnbpda in the presence of NaOH, in methanol, yielded a new water soluble dinuclear magnesium(II) complex, [Mg2(hpnbpda)(μ-OAc)(H2O)2] (2). DFT calculations have been performed for the structural optimization of complexes 1 and 2. The DFT optimized structure of complex 1 shows that two manganese(II) centers are in a distorted square pyramidal geometry, whereas the DFT optimized structure of complex 2 reveals that two magnesium(II) centers adopt a six-coordinate distorted octahedral geometry. To understand the mode of substrate binding and the mechanistic details of the active site metals in xylose/glucose isomerases (XGI), we have investigated the binding interactions of biologically important monosaccharides d-glucose and d-xylose with complexes 1 and 2, in aqueous alkaline solution by a combined approach of FTIR, UV-vis, fluorescence, and (13)C NMR spectroscopic techniques. Fluorescence spectra show the binding-induced gradual decrease in emission of complexes 1 and 2 accompanied by a significant blue shift upon increasing the concentration of sugar substrates. The binding modes of d-glucose and d-xylose with complex 2 are indicated by their characteristic coordination induced shift (CIS) values in (13)C NMR spectra for C1 and C2 carbon atoms. Copyright © 2013 Elsevier Ltd. All rights reserved.

Multi-metals column adsorption of lead(II), cadmium(II) and manganese(II) onto natural bentonite clay.

Science.gov (United States)

Alexander, Jock Asanja; Surajudeen, Abdulsalam; Aliyu, El-Nafaty Usman; Omeiza, Aroke Umar; Zaini, Muhammad Abbas Ahmad

2017-10-01

The present work was aimed at evaluating the multi-metals column adsorption of lead(II), cadmium(II) and manganese(II) ions onto natural bentonite. The bentonite clay adsorbent was characterized for physical and chemical properties using X-ray diffraction, X-ray fluorescence, Brunauer-Emmett-Teller surface area and cation exchange capacity. The column performance was evaluated using adsorbent bed height of 5.0 cm, with varying influent concentrations (10 mg/L and 50 mg/L) and flow rates (1.4 mL/min and 2.4 mL/min). The result shows that the breakthrough time for all metal ions ranged from 50 to 480 minutes. The maximum adsorption capacity was obtained at initial concentration of 10 mg/L and flow rate of 1.4 mL/min, with 2.22 mg/g of lead(II), 1.71 mg/g of cadmium(II) and 0.37 mg/g of manganese(II). The order of metal ions removal by natural bentonite is lead(II) > cadmium(II) > manganese(II). The sorption performance and the dynamic behaviour of the column were predicted using Adams-Bohart, Thomas, and Yoon-Nelson models. The linear regression analysis demonstrated that the Thomas and Yoon-Nelson models fitted well with the column adsorption data for all metal ions. The natural bentonite was effective for the treatment of wastewater laden with multi-metals, and the process parameters obtained from this work can be used at the industrial scale.

Effect of the tether on the Mg(II), Ca(II), Cu(II) and Fe(III) stability constants and pM values of chelating agents related to EDDHA.

Science.gov (United States)

Sierra, Miguel A; Gómez-Gallego, Mar; Alcázar, Roberto; Lucena, Juan J; Yunta, Felipe; García-Marco, Sonia

2004-11-07

The effect of the length and the structure of the tether on the chelating ability of EDDHA-like chelates have not been established. In this work, PDDHA (propylenediamine-N,N'-bis(o-hydroxyphenyl)acetic acid), BDDHA (butylenediamine-N,N'-bis(o-hydroxyphenyl)acetic acid) and XDDHA (p-xylylenediamine-N,N'-bis(o-hydroxyphenyl)acetic acid) have been obtained and their chemical behaviour has been studied and compared with that of EDDHA following our methodology. The purity of the chelating agents, and their protonation, Ca(II), Mg(II), Fe(III) and Cu(II) stability constants and pM values have been determined. The stability constants and pM values indicate that EDDHA forms the most stable chelates followed by PDDHA. However, the differences among the pFe values are small when a nutrient solution is used, and in these conditions the XDDHA/Fe(III) chelate is the most stable. The results obtained in this work indicate that all the chelating agents studied can be used as iron chlorosis correctors and they can be applied to soil/plant systems.

THE REDSHIFT DISTRIBUTION OF INTERVENING WEAK Mg II QUASAR ABSORBERS AND A CURIOUS DEPENDENCE ON QUASAR LUMINOSITY

Energy Technology Data Exchange (ETDEWEB)

Evans, Jessica L.; Churchill, Christopher W.; Nielsen, Nikole M.; Klimek, Elizabeth S. [New Mexico State University, Las Cruces, NM 88003 (United States); Murphy, Michael T. [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn, Melbourne, VIC 3122 (Australia)

2013-05-01

We have identified 469 Mg II {lambda}{lambda}2796, 2803 doublet systems having W{sub r} {>=} 0.02 A in 252 Keck/High Resolution Echelle Spectrometer and UVES/Very Large Telescope quasar spectra over the redshift range 0.1 < z < 2.6. Using the largest sample yet of 188 weak Mg II systems (0.02 A {<=}W{sub r} < 0.3 A), we calculate their absorber redshift path density, dN/dz. We find clear evidence of evolution, with dN/dz peaking at z {approx} 1.2, and that the product of the absorber number density and cross section decreases linearly with increasing redshift; weak Mg II absorbers seem to vanish above z {approx_equal} 2.7. If the absorbers are ionized by the UV background, we estimate number densities of 10{sup 6}-10{sup 9} Mpc{sup -3} for spherical geometries and 10{sup 2}-10{sup 5} Mpc{sup -3} for more sheetlike geometries. We also find that dN/dz toward intrinsically faint versus bright quasars differs significantly for weak and strong (W{sub r} {>=} 1.0 A) absorbers. For weak absorption, dN/dz toward bright quasars is {approx}25% higher than toward faint quasars (10{sigma} at low redshift, 0.4 {<=} z {<=} 1.4, and 4{sigma} at high redshift, 1.4 < z {<=} 2.34). For strong absorption the trend reverses, with dN/dz toward faint quasars being {approx}20% higher than toward bright quasars (also 10{sigma} at low redshift and 4{sigma} at high redshift). We explore scenarios in which beam size is proportional to quasar luminosity and varies with absorber and quasar redshifts. These do not explain dN/dz's dependence on quasar luminosity.

AN INDEPENDENT MEASUREMENT OF THE INCIDENCE OF Mg II ABSORBERS ALONG GAMMA-RAY BURST SIGHT LINES: THE END OF THE MYSTERY?

Energy Technology Data Exchange (ETDEWEB)

Cucchiara, A.; Prochaska, J. X. [Department of Astronomy and Astrophysics, UCO/Lick Observatory, University of California, 1156 High Street, Santa Cruz, CA 95064 (United States); Zhu, G.; Menard, B. [Department of Physics and Astronomy, Johns Hopkins University, Baltimore, MD 21218 (United States); Fynbo, J. P. U. [Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen (Denmark); Fox, D. B. [Department of Astronomy and Astrophysics, Pennsylvania State University, University Park, PA 16802 (United States); Chen, H.-W. [Department of Astronomy and Astrophysics, Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637 (United States); Cooksey, K. L. [MIT Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Avenue, 37-685, Cambridge, MA 02139 (United States); Cenko, S. B.; Bloom, J. S. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Perley, D. [Department of Astronomy, California Institute of Technology, MC 249-17, 1200 East California Blvd., Pasadena, CA 91125 (United States); Berger, E.; Chornock, R. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Tanvir, N. R. [Department of Physics and Astronomy, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); D' Elia, V. [Istituto Nazionale di Astrofisica-Osservatorio Astronomico di Roma, Via di Frascati 33, I-00040 Monte Porzio Catone (RM) (Italy); Lopez, S.; De Jaeger, T., E-mail: acucchia@ucolick.org [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago (Chile)

2013-08-20

In 2006, Prochter et al. reported a statistically significant enhancement of very strong Mg II absorption systems intervening the sight lines to gamma-ray bursts (GRBs) relative to the incidence of such absorption along quasar sight lines. This counterintuitive result has inspired a diverse set of astrophysical explanations (e.g., dust, gravitational lensing) but none of these has obviously resolved the puzzle. Using the largest set of GRB afterglow spectra available, we reexamine the purported enhancement. In an independent sample of GRB spectra with a survey path three times larger than Prochter et al., we measure the incidence per unit redshift of {>=}1 A rest-frame equivalent width Mg II absorbers at z Almost-Equal-To 1 to be l(z) = 0.18 {+-} 0.06. This is fully consistent with current estimates for the incidence of such absorbers along quasar sight lines. Therefore, we do not confirm the original enhancement and suggest those results suffered from a statistical fluke. Signatures of the original result do remain in our full sample (l(z) shows an Almost-Equal-To 1.5 enhancement over l(z){sub QSO}), but the statistical significance now lies at Almost-Equal-To 90% c.l. Restricting our analysis to the subset of high-resolution spectra of GRB afterglows (which overlaps substantially with Prochter et al.), we still reproduce a statistically significant enhancement of Mg II absorption. The reason for this excess, if real, is still unclear since there is no connection between the rapid afterglow follow-up process with echelle (or echellette) spectrographs and the detectability of strong Mg II doublets. Only a larger sample of such high-resolution data will shed some light on this matter.

Physicochemical impact studies of gamma rays on "aspirin" analgesics drug and its metal complexes in solid form: Synthesis, spectroscopic and biological assessment of Ca(II), Mg(II), Sr(II) and Ba(II) aspirinate complexes

Science.gov (United States)

Refat, Moamen S.; Sharshar, T.; Elsabawy, Khaled M.; Heiba, Zein K.

2013-09-01

Metal aspirinate complexes, M2(Asp)4, where M is Mg(II), Ca(II), Sr(II) or Ba(II) are formed by refluxed of aspirin (Asp) with divalent non-transition metal ions of group (II) and characterized by elemental analysis and spectroscopic measurements (infrared, electronic, 1H NMR, Raman, X-ray powder diffraction and scanning electron microscopy). Elemental analysis of the chelates suggests the stoichiometry is 1:2 (metal:ligand). Infrared spectra of the complexes agree with the coordination to the central metal atom through three donation sites of two oxygen atoms of bridge bidentate carboxylate group and oxygen atom of sbnd Cdbnd O of acetyl group. Infrared spectra coupled with the results of elemental analyzes suggested a distorted octahedral structure for the M(II) aspirinate complexes. Gamma irradiation was tested as a method for stabilization of aspirin as well as their complexes. The effect of gamma irradiation, with dose of 80 Gy, on the properties of aspirinate complexes was studied. The aspirinate chelates have been screened for their in vitro antibacterial activity against four bacteria, gram-positive (Bacillus subtilis and Staphylococcus aureus) and gram-negative (Escherichia coli and Pseudomonas aeruginosa) and two strains of fungus (Aspergillus flavus and Candida albicans). The metal chelates were shown to possess more antibacterial activity than the free aspirin chelate.

A study of the terrestrial thermosphere by remote sensing of OI dayglow in the far and extreme ultraviolet

International Nuclear Information System (INIS)

Cotton, D.M.

1991-01-01

The upper region of the Earth's atmosphere, the thermosphere, is a key part of the coupled solar-terrestrial system. An important method of obtaining information in the this region is through analysis of radiation excited through the interactions of the thermosphere with solar ionizing, extreme and far ultraviolet radiation. This dissertation presents one such study by the remote sensing of OI in the far and extreme ultraviolet dayglow. The research program included the development construction, and flight of a sounding rocket spectrometer to test this current understanding of the excitation and transport mechanisms of the OI 1356, 1304, 1027, and 989 angstrom emissions. This data set was analyzed using current electron and radiative transport models with the purpose of checking the viability of OI remote sensing; that is, whether existing models and input parameters are adequate to predict these detailed measurements. From discrepancies between modeled and measured emissions, inferences about these input parameters were made. Among other things, the data supports a 40% optically thick cascade contribution to the 1304 angstrom emission. From upper lying states corresponding to 1040, 1027 and 989 angstrom about half of this cascade has been accounted for in this study. There is also evidence that the Lyman β airglow from the geo-corona contributes a significant proportion (30-50%) to the OI 1027 angstrom feature. Furthermore, the photoelectron contribution to the 1027 angstrom feature appears to be underestimated in the current models by a factor of 20

Replacement of Ser108 in Plasmodium falciparum enolase results in weak Mg(II) binding: role of a parasite-specific pentapeptide insert in stabilizing the active conformation of the enzyme.

Science.gov (United States)

Dutta, Sneha; Mukherjee, Debanjan; Jarori, Gotam K

2015-06-01

A distinct structural feature of Plasmodium falciparum enolase (Pfeno) is the presence of a five amino acid insert -104EWGWS108- that is not found in host enolases. Its conservation among apicomplexan enolases has raised the possibility of its involvement in some important physiological function(s). Deletion of this sequence is known to lower k(cat)/K(m), increase K(a) for Mg(II) and convert dimer into monomers (Vora HK, Shaik FR, Pal-Bhowmick I, Mout R & Jarori GK (2009) Arch Biochem Biophys 485, 128-138). These authors also raised the possibility of the formation of an H-bond between Ser108 and Leu49 that could stabilize the apo-Pfeno in an active closed conformation that has high affinity for Mg(II). Here, we examined the effect of replacement of Ser108 with Gly/Ala/Thr on enzyme activity, Mg(II) binding affinity, conformational states and oligomeric structure and compared it with native recombinant Pfeno. The results obtained support the view that Ser108 is likely to be involved in the formation of certain crucial H-bonds with Leu49. The presence of these interactions can stabilize apo-Pfeno in an active closed conformation similar to that of Mg(II) bound yeast enolase. As predicted, S108G/A-Pfeno variants (where Ser108-Leu49 H-bonds are likely to be disrupted) were found to exist in an open conformation and had low affinity for Mg(II). They also required Mg(II) induced conformational changes to acquire the active closed conformational state essential for catalysis. The possible physiological relevance of apo-Pfeno being in such an active state is discussed. © 2015 FEBS.

The structure of the local interstellar medium. VI. New Mg II, Fe II, and Mn II observations toward stars within 100 pc

International Nuclear Information System (INIS)

Malamut, Craig; Redfield, Seth; Linsky, Jeffrey L.; Wood, Brian E.; Ayres, Thomas R.

2014-01-01

We analyze high-resolution spectra obtained with the Space Telescope Imaging Spectrograph onboard the Hubble Space Telescope toward 34 nearby stars (≤100 pc) to record Mg II, Fe II, and Mn II absorption due to the local interstellar medium (LISM). Observations span the entire sky, probing previously unobserved regions of the LISM. The heavy ions studied in this survey produce narrow absorption features that facilitate the identification of multiple interstellar components. We detected one to six individual absorption components along any given sight line, and the number of absorbers roughly correlates with the pathlength. This high-resolution near-ultraviolet (NUV) spectroscopic survey was specifically designed for sight lines with existing far-UV (FUV) observations. The FUV spectra include many intrinsically broad absorption lines (i.e., of low atomic mass ions) and are often observed at medium resolution. The LISM NUV narrow-line absorption component structure presented here can be used to more accurately interpret the archival FUV observations. As an example of this synergy, we present a new analysis of the temperature and turbulence along the line of sight toward ε Ind. The new observations of LISM velocity structure are also critical in the interpretation of astrospheric absorption derived from fitting the saturated H I Lyα profile. As an example, we reanalyze the spectrum of λ And and find that this star likely does have an astrosphere. Two stars in the sample that have circumstellar disks (49 Cet and HD141569) show evidence for absorption due to disk gas. Finally, the substantially increased number of sight lines is used to test and refine the three-dimensional kinematic model of the LISM and search for previously unidentified clouds within the Local Bubble. We find that every prediction made by the Redfield and Linsky kinematic model of the LISM is confirmed by an observed component in the new lines of sight.

The redshift number density evolution of Mg II absorption systems

International Nuclear Information System (INIS)

Chen Zhi-Fu

2013-01-01

We make use of the recent large sample of 17 042 Mg II absorption systems from Quider et al. to analyze the evolution of the redshift number density. Regardless of the strength of the absorption line, we find that the evolution of the redshift number density can be clearly distinguished into three different phases. In the intermediate redshift epoch (0.6 ≲ z ≲ 1.6), the evolution of the redshift number density is consistent with the non-evolution curve, however, the non-evolution curve over-predicts the values of the redshift number density in the early (z ≲ 0.6) and late (z ≳ 1.6) epochs. Based on the invariant cross-section of the absorber, the lack of evolution in the redshift number density compared to the non-evolution curve implies the galaxy number density does not evolve during the middle epoch. The flat evolution of the redshift number density tends to correspond to a shallow evolution in the galaxy merger rate during the late epoch, and the steep decrease of the redshift number density might be ascribed to the small mass of halos during the early epoch.

Observed IRIS Profiles of the h and k Doublet of Mg II and Comparison with Profiles from Quiescent Prominence NLTE Models

Czech Academy of Sciences Publication Activity Database

Vial, J. C.; Pelouze, G.; Heinzel, Petr; Kleint, L.; Anzer, U.

2016-01-01

Roč. 291, č. 1 (2016), s. 67-87 ISSN 0038-0938 Institutional support: RVO:67985815 Keywords : Mg II lines * non-LTE diagnostic * Sun prominences Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.682, year: 2016

Structures and Spectroscopy Studies of Two M(II-Phosphonate Coordination Polymers Based on Alkaline Earth Metals (M = Ba, Mg

Directory of Open Access Journals (Sweden)

Kui-Rong Ma

2013-01-01

Full Text Available The two examples of alkaline-earth M(II-phosphonate coordination polymers, [Ba2(L(H2O9]·3H2O (1 and [Mg1.5(H2O9]·(L-H21.5·6H2O (2 (H4L = H2O3PCH2N(C4H8NCH2PO3H2, N,N′-piperazinebis(methylenephosphonic acid, (L-H2 = O3PH2CHN(C4H8NHCH2PO3 have been hydrothermally synthesized and characterized by elemental analysis, FT-IR, PXRD, TG-DSC, and single-crystal X-ray diffraction. Compound 1 possesses a 2D inorganic-organic alternate arrangement layer structure built from 1D inorganic chains through the piperazine bridge, in which the ligand L−4 shows two types of coordination modes reported rarely at the same time. In 1, both crystallographic distinct Ba(1 and Ba(2 ions adopt 8-coordination two caps and 9-coordination three caps triangular prism geometry structures, respectively. Compound 2 possesses a zero-dimensional mononuclear structure with two crystallographic distinct Mg(II ions. Free metal cations   [MgO6]n2+ and uncoordinated anions (L-H2n2- are joined together by static electric force. Results of photoluminescent measurement indicate three main emission bands centered at 300 nm, 378.5 nm, and 433 nm for 1 and 302 nm, 378 nm, and 434.5 nm for 2 (λex=235 nm, respectively. The high energy emissions could be derived from the intraligand π∗-n transition stations of H4L (310 nm and 382 nm, λex=235 nm, while the low energy emission (>400 nm of 1-2 may be due to the coordination effect with metal(II ions.

Emodin (1,3,8-trihydroxy-6-methylanthraquinone): a spectrophotometric reagent for the determination of beryllium(II), magnesium(II) and calcium(II)

International Nuclear Information System (INIS)

Pal, T.; Jana, N.R.

1993-01-01

The individual determination of Be II , Mg II or Ca II by conventional spectrophotometry and simultaneous determination of Mg II and Ca II in mixtures by first-derivative spectrophotometry are possible at trace levels, using emodin (1,3,8-trihydroxy-6-methylanthraquinone) as spectrophotometric reagent. Interference from other metal species, application of these methods to rock samples and statistical analysis of the results are discussed. (author)

Efficiency of Chitosan for the Removal of Pb (II, Fe (II and Cu (II Ions from Aqueous Solutions

Directory of Open Access Journals (Sweden)

Soheil Sobhanardakani

2014-09-01

Full Text Available Background: Heavy metals have been recognized as harmful environmental pollutant known to produce highly toxic effects on different organs and systems of both humans and animals. The aim of this paper is to evaluate the adsorption potential of chitosan for the removal of Pb(II, Fe(II and Cu(II ions from aqueous solutions. Methods: This study was conducted in laboratory scale. In this paper chitosan has been used as an adsorbent for the removal of Pb(II, Fe(II and Cu(II from aqueous solution. In batch tests, the effects of parameters like pH solution (1.0-8.0, initial metal concentrations (100-1000 mgL-1, contact time (5.0-150 min and adsorbent dose (1.0-7.0 g on the adsorption process were studied. Results: The results showed that the adsorption of Pb(II, Fe(II and Cu(II ions on chitosan strongly depends on pH. The experimental isothermal data were analyzed using the Langmuir and Freundlich equations and it was found that the removal process followed the Langmuir isotherm and maximum adsorption capacity for the adsorption of Pb(II, Fe(II and Cu(II ions by the chitosan were 55.5mg g−1, 71.4 mg g−1 and 59 mg g−1, respectively, under equilibrium conditions at 25±1 ºC. The adsorption process was found to be well described by the pseudo-second-order rate model. Conclusion: The obtained results showed that chitosan is a readily, available, economic adsorbent and was found suitable for removing Pb(II, Fe(II and Cu(II ions from aqueous solution.

Tetra-2,3-pyrazinoporphyrazines with externally appended pyridine rings. 15. Effects of the pyridyl substituents and fused exocyclic rings on the UV-visible spectroscopic properties of Mg(II)-porphyrazines: a combined experimental and DFT/TDDFT study.

Science.gov (United States)

Donzello, Maria Pia; De Mori, Giorgia; Viola, Elisa; Ercolani, Claudio; Ricciardi, Giampaolo; Rosa, Angela

2014-08-04

Two new Mg(II) porphyrazine macrocycles, the octakis(2-pyridyl)porphyrazinato-magnesium(II), [Py8PzMg(H2O)], and the tetrakis-[6,7-di(2-pyridyl)quinoxalino]porphyrazinato-magnesium(II), [Py8QxPzMg(H2O)], were prepared by Mg-template macrocyclization processes, and their general physicochemical properties were examined. The previously reported porphyrazine analog, the tetrakis-2,3-[5,6-di(2-pyridyl)-pyrazino]porphyrazinato-magnesium(II), [Py8PyzPzMg(H2O)], has been also considered in the present work. The UV-visible solution spectra in nonaqueous solvents of this triad of externally octapyridinated Mg(II) complexes exhibit the usual profile observed for phthalocyanine and porphyrazine macrocycles, with intense absorptions in the Soret (300-450 nm) and Q band (600-800 nm) regions. It is observed that the Q band maximum sensibly shifts toward the red with peak values at 635 → 658 → 759 nm along the series [Py8PzMg(H2O)], [Py8PyzPzMg(H2O)], and [Py8QxPzMg(H2O)], as the extension of the macrocycle π-system increases. TDDFT calculations of the electronic absorption spectra were performed for the related water-free model compounds [Py8PzMg], [Py8PyzPzMg], and [Py8QxPzMg] to provide an interpretation of the UV-visible spectral changes occurring upon introduction of the pyrazine and quinoxaline rings at the periphery of the Pz macrocycle. To discriminate the electronic effects of the fused exocyclic rings from those of the appended 2-pyridyl rings, the UV-visible spectra of [PzMg] and [PyzPzMg] were also theoretically investigated. The theoretical results prove to agree very well with the experimental data, providing an accurate description of the UV-visible spectra. The observed spectral changes are interpreted on the basis of the electronic structure changes occurring along the series.

Correlated O and Mg isotopic anomalies in Allende inclusions: II. Magnesium

International Nuclear Information System (INIS)

Wasserburg, G.J.; Lee, T.; Papanastassiou, D.A.

1977-01-01

Mg in two Allende Ca-Al rich inclusions shows large isotopic, mass-dependent fractionation which enriched the heavier isotopes. After normalization, Mg in these inclusions shows negative delta 26 Mg which appears to require the presence of nuclear effects in Mg distinct from 26 Al decay. The Mg mass fractionation is correlated with distinct but smaller fractionation effects for O reported by Clayton and Mayeda for the same inclusions (see companion paper). The observation of distinctive but uniform Mg isotopic composition in different phases within single Allende inclusions indicates that nuclear effects in O and Mg are not due to the entrapment of interstellar carrier grains as discrete entities, which are preserved as remnants, but are instead due to a homogenized mixture of components of extraordinary isotopic composition mixed with a component of ordinary solar system material and subjected to isotopic fractionation. The distinct O isotopic composition of different phases within a single inclusion is believed to be due to incomplete back-reaction of the higher temperature condensates with a cooler solar nebula of ''normal '' composition. The processes responsible for the O and Mg nuclear effects and the astrophysical site of their occurrence remain undefined

THE SMOOTH Mg II GAS DISTRIBUTION THROUGH THE INTERSTELLAR/EXTRA-PLANAR/HALO INTERFACE

International Nuclear Information System (INIS)

Kacprzak, Glenn G.; Cooke, Jeff; Ryan-Weber, Emma V.; Churchill, Christopher W.; Nielsen, Nikole M.

2013-01-01

We report the first measurements of Mg II absorption systems associated with spectroscopically confirmed z ∼ 0.1 star-forming galaxies at projected distances of D r (2796), and impact parameter, D, represented by a single log-linear relation derived by Nielsen et al. (MAGIICAT) that converges to ∼2 Å at D = 0 kpc. Incorporating MAGIICAT, we find that the halo gas covering fraction is unity below D ∼ 25 kpc. We also report that our D r (2796) distributions of the Milky Way interstellar medium (ISM) and ISM+halo. In addition, quasar sight lines of intermediate redshift galaxies with 6 r (2796)-D relation out to large scales across a variety of gas-phase conditions and is maintained through the halo/extra-planar/ISM interfaces, which is remarkable considering their kinematic complexity. These low-redshift, small impact parameter absorption systems are the first steps to bridge the gap between quasar absorption-line studies and H I observations of the circumgalactic medium

TESTING THE POSSIBLE INTRINSIC ORIGIN OF THE EXCESS VERY STRONG Mg II ABSORBERS ALONG GAMMA-RAY BURST LINES-OF-SIGHT

International Nuclear Information System (INIS)

Cucchiara, A.; Jones, T.; Charlton, J. C.; Fox, D. B.; Einsig, D.; Narayanan, A.

2009-01-01

The startling discovery by Prochter et al. that the frequency of very strong (W r (2796)>1 A) Mg II absorbers along gamma-ray burst (GRB) lines of sight ([dN/dz] GRB = 0.90) is more than three times the frequency along quasar lines of sight ([dN/dz] QSO = 0.24), over similar redshift ranges, has yet to be understood. In particular, explanations appealing to dust antibias in quasar samples, partial covering of the quasar sources, and gravitational-lensing amplification of the GRBs have all been carefully examined and found wanting. We therefore reconsider the possibility that the excess of very strong Mg II absorbers toward GRBs is intrinsic either to the GRBs themselves or to their immediate environment, and associated with bulk outflows with velocities as large as v max ∼ 0.3c. In order to examine this hypothesis, we accumulate a sample of 27 W r (2796)>1 A absorption systems found toward 81 quasars, and compare their properties to those of 8 W r (2796) > 1 A absorption systems found toward six GRBs; all systems have been observed at high spectral resolution (R = 45, 000) using the Ultraviolet and Visual Echelle Spectrograph on the Very Large Telescope. We make multiple comparisons of the absorber properties across the two populations, testing for differences in metallicity, ionization state, abundance patterns, dust abundance, kinematics, and phase structure. We find no significant differences between the two absorber populations using any of these metrics, implying that, if the excess of absorbers along GRB lines of sight are indeed intrinsic, they must be produced by a process which has strong similarities to the processes yielding strong Mg II systems associated with intervening galaxies. Although this may seem a priori unlikely, given the high outflow velocities required for any intrinsic model, we note that the same conclusion was reached, recently, with respect to the narrow absorption line systems seen in some quasars.

Selective Hg(II) adsorption from aqueous solutions of Hg(II) and Pb(II) by hydrolyzed acrylamide-grafted PET films.

Science.gov (United States)

Rahman, Nazia; Sato, Nobuhiro; Sugiyama, Masaaki; Hidaka, Yoshiki; Okabe, Hirotaka; Hara, Kazuhiro

2014-01-01

Selective Hg(II) adsorption from aqueous solutions of Hg(II) and Pb(II) using hydrolyzed acrylamide (AAm)-grafted polyethylene terephthalate (PET) films was examined to explore the potential reuse of waste PET materials. Selective recovery of Hg(II) from a mixture of soft acids with similar structure, such as Hg(II) and Pb(II), is important to allow the reuse of recovered Hg(II). An adsorbent for selective Hg(II) adsorption was prepared by γ-ray-induced grafting of AAm onto PET films followed by partial hydrolysis through KOH treatment. The adsorption capacity of the AAm-grafted PET films for Hg(II) ions increased from 15 to 70 mg/g after partial hydrolysis because of the reduction of hydrogen bonding between -CONH2 groups and the corresponding improved access of metal ions to the amide groups. The prepared adsorbent was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. The absorbent film showed high selectivity for the adsorption of Hg(II) over Pb(II) throughout the entire initial metal concentration range (100-500 mg/L) and pH range (2.2-5.6) studied. The high selectivity is attributed to the ability of Hg(II) ions to form covalent bonds with the amide groups. The calculated selectivity coefficient for the adsorbent binding Hg(II) over Pb(II) was 19.2 at pH 4.5 with an initial metal concentration of 100 mg/L. Selective Hg(II) adsorption equilibrium data followed the Langmuir model and kinetic data were well fitted by a pseudo-second-order equation. The adsorbed Hg(II) and Pb(II) ions were effectively desorbed from the adsorbent film by acid treatment, and the regenerated film showed no marked loss of adsorption capacity upon reuse for selective Hg(II) adsorption.

Etch Pit Studies of II-VI-Wide Bandgap Semiconductor Materials ZnSe, ZnCdSe, and ZnCdMgSe Grown on InP

National Research Council Canada - National Science Library

Semendy, Fred

1999-01-01

Etch pit density (EPD) determination studies have been conducted on II-VI semiconductor materials ZnSe, ZnCdSe, and ZnCdMgSe grown on InP surfaces for the first time by using various etching solutions under different...

Transformation of Mg-bearing amorphous calcium carbonate to Mg-calcite - In situ monitoring

Science.gov (United States)

Purgstaller, Bettina; Mavromatis, Vasileios; Immenhauser, Adrian; Dietzel, Martin

2016-02-01

The formation of Mg-bearing calcite via an amorphous precursor is a poorly understood process that is of relevance for biogenic and abiogenic carbonate precipitation. In order to gain an improved insight on the controls of Mg incorporation in calcite formed via an Mg-rich amorphous calcium carbonate (Mg-ACC) precursor, the precipitation of Mg-ACC and its transformation to Mg-calcite was monitored by in situ Raman spectroscopy. The experiments were performed at 25.0 ± 0.03 °C and pH 8.3 ± 0.1 and revealed two distinct pathways of Mg-calcite formation: (i) At initial aqueous Mg/Ca molar ratios ⩽ 1:6, Mg-calcite formation occurs via direct precipitation from solution. (ii) Conversely, at higher initial Mg/Ca molar ratios, Mg-calcite forms via an intermediate Mg-rich ACC phase. In the latter case, the final product is a calcite with up to 20 mol% Mg. This Mg content is significant higher than that of the Mg-rich ACC precursor phase. Thus, a strong net uptake of Mg ions from the solution into the crystalline precipitate throughout and also subsequent to ACC transformation is postulated. Moreover, the temporal evolution of the geochemical composition of the reactive solution and the Mg-ACC has no significant effect on the obtained ;solubility product; of Mg-ACC. The enrichment of Mg in calcite throughout and subsequent to Mg-ACC transformation is likely affected by the high aqueous Mg/Ca ratio and carbonate alkalinity concentrations in the reactive solution. The experimental results have a bearing on the formation mechanism of Mg-rich calcites in marine early diagenetic environments, where high carbonate alkalinity concentrations are the rule rather than the exception, and on the insufficiently investigated inorganic component of biomineralisation pathways in many calcite secreting organisms.

Artificial neural networks study of the catalytic reduction of resazurin: stopped-flow injection kinetic-spectrophotometric determination of Cu(II) and Ni(II)

International Nuclear Information System (INIS)

Magni, Diana M.; Olivieri, Alejandro C.; Bonivardi, Adrian L.

2005-01-01

An artificial neural network (ANN) procedure was used in the development of a catalytic spectrophotometric method for the determination of Cu(II) and Ni(II) employing a stopped-flow injection system. The method is based on the catalytic action of these ions on the reduction of resazurin by sulfide. ANNs trained by back-propagation of errors allowed us to model the systems in a concentration range of 0.5-6 and 1-15 mg l -1 for Cu(II) and Ni(II), respectively, with a low relative error of prediction (REP) for each cation: REP Cu(II) = 0.85% and REP Ni(II) = 0.79%. The standard deviations of the repeatability (s r ) and of the within-laboratory reproducibility (s w ) were measured using standard solutions of Cu(II) and Ni(II) equal to 2.75 and 3.5 mg l -1 , respectively: s r [Cu(II)] = 0.039 mg l -1 , s r [Ni(II)] = 0.044 mg l -1 , s w [Ni(II)] = 0.045 mg l -1 and s w [Ni(II)] = 0.050 mg l -1 . The ANNs-kinetic method has been applied to the determination of Cu(II) and Ni(II) in electroplating solutions and provided satisfactory results as compared with flame atomic absorption spectrophotometry method. The effect of resazurin, NaOH and Na 2 S concentrations and the reaction temperature on the analytical sensitivity is discussed

Enhanced removal of Cd(II) and Pb(II) by composites of mesoporous carbon stabilized alumina

Energy Technology Data Exchange (ETDEWEB)

Yang, Weichun [Department of Environmental Engineering, School of Metallurgy and Environment, Central South University, Lushan South Road 932, Changsha 410017 (China); Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Lushan South Road 932, Changsha 410017 (China); Tang, Qiongzhi; Wei, Jingmiao; Ran, Yajun [Department of Environmental Engineering, School of Metallurgy and Environment, Central South University, Lushan South Road 932, Changsha 410017 (China); Chai, Liyuan [Department of Environmental Engineering, School of Metallurgy and Environment, Central South University, Lushan South Road 932, Changsha 410017 (China); Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Lushan South Road 932, Changsha 410017 (China); Wang, Haiying, E-mail: haiyw25@163.com [Department of Environmental Engineering, School of Metallurgy and Environment, Central South University, Lushan South Road 932, Changsha 410017 (China); Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Lushan South Road 932, Changsha 410017 (China)

2016-04-30

Graphical abstract: - Highlights: • Mesoporous carbon stabilized alumina was prepared by one-pot hard-templating method. • MC/Al{sub 2}O{sub 3} showed excellent performance for Cd(II) and Pb(II) adsorption. • Enhanced adsorption was due to the high surface area and special functional groups. - Abstract: A novel adsorbent of mesoporous carbon stabilized alumina (MC/Al{sub 2}O{sub 3}) was synthesized through one-pot hard-templating method. The adsorption potential of MC/Al{sub 2}O{sub 3} for Cd(II) and Pb(II) from aqueous solution was investigated compared with the mesoporous carbon. The results indicated the MC/Al{sub 2}O{sub 3} showed excellent performance for Cd(II) and Pb(II) removal, the adsorption capacity reached 49.98 mg g{sup −1} for Cd(II) with initial concentration of 50 mg L{sup −1} and reached 235.57 mg g{sup −1} for Pb(II) with initial concentration of 250 mg L{sup −1}, respectively. The kinetics data of Cd(II) adsorption demonstrated that the Cd(II) adsorption rate was fast, and the removal efficiencies with initial concentration of 10 and 50 mg L{sup −1} can reach up 99% within 5 and 20 min, respectively. The pseudo-second-order kinetic model could describe the kinetics of Cd(II) adsorption well, indicating the chemical reaction was the rate-controlling step. The mechanism for Cd(II) and Pb(II) adsorption by MC/Al{sub 2}O{sub 3} was investigated by X-ray photoelectron spectroscopy (XPS) and Fourier transformed infrared spectroscopy (FTIR), and the results indicated that the excellent performance for Cd(II) and Pb(II) adsorption of MC/Al{sub 2}O{sub 3} was mainly attributed to its high surface area and the special functional groups of hydroxy-aluminum, hydroxyl, carboxylic through the formation of strong surface complexation or ion-exchange. It was concluded that MC/Al{sub 2}O{sub 3} can be recognized as an effective adsorbent for removal of Cd(II) and Pb(II) in aqueous solution.

DNA damage by the cobalt (II) and zinc (II) complexes of ...

African Journals Online (AJOL)

Using the single cell gel electrophoresis method, the tetraazamacrocycle Zn(II) complex (Zn(II)-L) and the tetraazamacrocycle Co(II) complex (Co(II)-L) were investigated focusing on their DNA damage to Tetrahymena thermophila. When the cells were treated with the 0.05, 0.25 and 0.50 mg/ml Zn(II)-L, the tail length ...

Kinetic study on adsorption of Cr(VI), Ni(II), Cd(II) and Pb(II) ions from aqueous solutions using activated carbon prepared from Cucumis melo peel

Science.gov (United States)

Manjuladevi, M.; Anitha, R.; Manonmani, S.

2018-03-01

The adsorption of Cr(VI), Ni(II), Cd(II) and Pb(II), ions from aqueous solutions by Cucumis melo peel-activated carbon was investigated under laboratory conditions to assess its potential in removing metal ions. The adsorption behavior of metal ions onto CMAC was analyzed with Elovich, intra-particle diffusion rate equations and pseudo-first-order model. The rate constant of Elovich and intra-particle diffusion on CMAC increased in the sequence of Cr(VI) > Ni(II) > Cd(II) > Pb(II). According to the regression coefficients, it was observed that the kinetic adsorption data can fit better by the pseudo-first-order model compared to the second-order Lagergren's model with R 2 > 0.957. The maximum adsorption of metal ions onto the CMAC was found to be 97.95% for Chromium(VI), 98.78% for Ni(II), 98.55% for Pb(II) and 97.96% for Cd(II) at CMAC dose of 250 mg. The adsorption capacities followed the sequence Ni(II) ≈ Pb(II) > Cr(VI) ≈ Cd(II) and Ni(II) > Pb(II) > Cd(II) > Cr(VI). The optimum adsorption conditions selected were adsorbent dosage of 250 mg, pH of 3.0 for Cr(VI) and 6.0 for Ni(II), Cd(II) and Pb(II), adsorption concentration of 250 mg/L and contact time of 180.

Search for atmospheric holes with the Viking cameras

International Nuclear Information System (INIS)

Frank, L.A.; Sigwarth, J.B.; Craven, J.D.

1989-01-01

Images taken with the two ultraviolet cameras on board the Viking spacecraft were examined for evidence of transient decreases of Earth's ultraviolet dayglow. Comparison of near-limb observations of dayglow intensities with those at smaller angles to the nadir with the camera sensitive to OI 130.4 nm emissions supports the existence of transient decreases in the near-nadir dayglow. However, the amount of near-nadir imaging is severely limited and only several significant events are found. More decisive confirmation of the existence of such transient decreases must await a larger survey from another spacecraft. The diameters of these regions as detected with Viking are ∼50 to 100 km. Occurrence frequencies, intensity decreases, and dimensions for these clusters of darkened pixels are similar to those previously reported for such events, or atmospheric holes, as seen in images of the ultraviolet dayglow with Dynamics Explorer 1

PREDICTING Lyα AND Mg II FLUXES FROM K AND M DWARFS USING GALAXY EVOLUTION EXPLORER ULTRAVIOLET PHOTOMETRY

International Nuclear Information System (INIS)

Shkolnik, Evgenya L.; Rolph, Kristina A.; Peacock, Sarah; Barman, Travis S.

2014-01-01

A star's ultraviolet (UV) emission can greatly affect the atmospheric chemistry and physical properties of closely orbiting planets with the potential for severe mass loss. In particular, the Lyα emission line at 1216 Å, which dominates the far-ultraviolet (FUV) spectrum, is a major source of photodissociation of important atmospheric molecules such as water and methane. The intrinsic flux of Lyα, however, cannot be directly measured due to the absorption of neutral hydrogen in the interstellar medium and contamination by geocoronal emission. To date, reconstruction of the intrinsic Lyα line based on Hubble Space Telescope spectra has been accomplished for 46 FGKM nearby stars, 28 of which have also been observed by the Galaxy Evolution Explorer (GALEX). Our investigation provides a correlation between published intrinsic Lyα and GALEX far- and near-ultraviolet (NUV) chromospheric fluxes for K and M stars. The negative correlations between the ratio of the Lyα to the GALEX fluxes reveal how the relative strength of Lyα compared to the broadband fluxes weakens as the FUV and NUV excess flux increase. We also correlate GALEX fluxes with the strong NUV Mg II h+k spectral emission lines formed at lower chromospheric temperatures than Lyα. The reported correlations provide estimates of intrinsic Lyα and Mg II fluxes for the thousands of K and M stars in the archived GALEX all-sky surveys. These will constrain new stellar upper atmosphere models for cool stars and provide realistic inputs to models describing exoplanetary photochemistry and atmospheric evolution in the absence of UV spectroscopy

Adsorption of heavy metals from aqueous solutions by Mg-Al-Zn mingled oxides adsorbent.

Science.gov (United States)

El-Sayed, Mona; Eshaq, Gh; ElMetwally, A E

2016-10-01

In our study, Mg-Al-Zn mingled oxides were prepared by the co-precipitation method. The structure, composition, morphology and thermal stability of the synthesized Mg-Al-Zn mingled oxides were analyzed by powder X-ray diffraction, Fourier transform infrared spectrometry, N 2 physisorption, scanning electron microscopy, differential scanning calorimetry and thermogravimetry. Batch experiments were performed to study the adsorption behavior of cobalt(II) and nickel(II) as a function of pH, contact time, initial metal ion concentration, and adsorbent dose. The maximum adsorption capacity of Mg-Al-Zn mingled oxides for cobalt and nickel metal ions was 116.7 mg g -1 , and 70.4 mg g -1 , respectively. The experimental data were analyzed using pseudo-first- and pseudo-second-order kinetic models in linear and nonlinear regression analysis. The kinetic studies showed that the adsorption process could be described by the pseudo-second-order kinetic model. Experimental equilibrium data were well represented by Langmuir and Freundlich isotherm models. Also, the maximum monolayer capacity, q max , obtained was 113.8 mg g -1 , and 79.4 mg g -1 for Co(II), and Ni(II), respectively. Our results showed that Mg-Al-Zn mingled oxides can be used as an efficient adsorbent material for removal of heavy metals from industrial wastewater samples.

Removal of nickel(II and palladium(II from surface waters

Directory of Open Access Journals (Sweden)

V. Sharifzade

2013-04-01

Full Text Available A new sorbent was prepared using alumina and 5-Br-PADAP, and its adsorption ability for the removal of Ni(II and Pd(II from different waters was investigated. The procedure is based on retention of the analytes on the alumina load with 5-Br-PADAP at pH ~ 6. The separation/preconcentration conditions for the quantitative recoveries were investigated. The limit of detections (LOD based on three times the standard deviations of the blank, were 0.187 and 0.253 ng mL-1 for Ni(II and Pd(II, respectively. Obtained sorption capacities for 1 g sorbent were 6.0 mg Ni(II and 11.0 mg Pd(II. The linearity was maintained in the concentration range of 0.625 to 6.0 ng mL-1 for Ni(II and 0.416 to 7.0 ng mL-1 for Pd(II in the original solution. Eight replicate determinations of a mixture containing 2.0 µg mL-1 each of the elements in the final solution gave relative standard deviation of ±0.82 and ±1.12% for Ni(II and Pd(II, respectively. The proposed method was successfully applied to the determination trace amounts of Ni(II and Pd(II in the surface water samples.DOI: http://dx.doi.org/10.4314/bcse.v27i1.2

Phase diagrams for systems Cu2S-AIIS (AII=Mg, Ca, Sr, Ba)

International Nuclear Information System (INIS)

Andreev, O.V.; Sikerina, N.V.; Solov'eva, A.V.

2005-01-01

By the methods of physicochemical analysis phase diagrams of Cu 2 S-A II S (A II =Mg, Ca, Sr, Ba) systems are studied. The system Cu 2 S-SrS is of eutectic type with eutectic coordinates 1095 K and 21.5 mol.% of SrS. Solubility of SrS in Cu 2 S is 2 mol.% at 1095 K. Regularities of phase diagram changes of Cu 2 S-A II S (A II =Mg, Ca, Sr, Ba) system are determined. Thermodynamic analysis is done [ru

Chelation of Cu(II, Zn(II, and Fe(II by Tannin Constituents of Selected Edible Nuts

Directory of Open Access Journals (Sweden)

Magdalena Karamać

2009-12-01

Full Text Available The tannin fractions isolated from hazelnuts, walnuts and almonds were characterised by colorimetric assays and by an SE-HPLC technique. The complexation of Cu(II and Zn(II was determined by the reaction with tetramethylmurexide, whereas for Fe(II, ferrozine was employed. The walnut tannins exhibited a significantly weaker reaction with the vanillin/HCl reagent than hazelnut and almond tannins, but the protein precipitation capacity of the walnut fraction was high. The SE-HPLC chromatogram of the tannin fraction from hazelnuts revealed the presence of oligomers with higher molecular weights compared to that of almonds. Copper ions were most effectively chelated by the constituents of the tannin fractions of hazelnuts, walnuts and almonds. At a 0.2 mg/assay addition level, the walnut tannins complexed almost 100% Cu(II. The Fe(II complexation capacities of the tannin fractions of walnuts and hazelnuts were weaker in comparison to that of the almond tannin fraction, which at a 2.5 mg/assay addition level, bound Fe(II by ~90%. The capacity to chelate Zn(II was quite varied for the different nut tannin fractions: almond tannins bound as much as 84% Zn(II, whereas the value for walnut tannins was only 8.7%; and for hazelnut tannins, no Zn(II chelation took place at the levels tested.

Second-line chemotherapy of disseminated malignant melanoma with cystemustine at 60 mg/m2: a phase II trial.

Science.gov (United States)

Thivat, Emilie; Durando, Xavier; D'Incan, Michel; Cure, Hervé; Mouret-Reynier, Marie-Ange; Madelmont, Jean-Claude; Souteyrand, Pierre; Chollet, Philippe

2005-10-01

Nitrosoureas possess some anti-tumor activity as a single agent in metastatic melanoma (MM). In a phase II trial, we evaluated the anti-tumor effects of cystemustine chemotherapy, a new nitrosourea, as a second-line treatment. Patients were required to have histologic evidence of disseminated MM and had failed in first-line chemotherapy. Treatment comprised cystemustine given at a dose of 60 mg/m every 2 weeks by a 15-min infusion. From February 1997 to September 1999, 22 patients (median age 66 years) were enrolled and were assessable. Two complete responses, one partial response, three stable diseases and 16 progressions were observed, giving an overall response rate of 13.6%. Median duration of response was 10 months (range 4-63). Median survival of responders and non-responders was 11 and 4 months, respectively. However, hematological toxicity, particularly thrombopenia, was a limiting factor for one-third of patients. We conclude that cystemustine at 60 mg/m is active in patients who progressed after one line of chemotherapy in advanced disease, and offers the possibility of complete responses and long durations of these responses.

Hexagonal perovskites with cationic vacancies. 23. Rhombohedral 12 L stacking polytypes of type Ba/sub 3/LaBsup(II)Resup(VII)Wsup(VI)vacantO/sub 12/ with Bsup(II) = Mg, Co, Ni, Cu, Zn

Energy Technology Data Exchange (ETDEWEB)

Herrmann, M; Kemmler-Sack, S [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

1980-11-01

The rhombohedral 12 L pervoskites with cationic vacancies of type Ba/sub 3/LaBsup(II)ReWvacantO/sub 12/ with Bsup(II) = Mg, Co, Ni, Cu, Zn are isotypic. According to intensity calculations on powder patterns of Ba/sub 3/LaZnReWvacantO/sub 12/ the series crystallize in the space group R-3m with the sequence (hhcc)/sub 3/; the refined, intensity related R' value is 5.7%. The octahedral net consists of blocks of three face connected octahedra with central void (ReWvacantO/sub 12/ units), which are linked via common corners through single octahedra, occupied by zinc.

Compounds of the type Ba/sub 3/Bsup(II)M/sub 2/sup(V)O/sub 9/ with Bsup(II) = Mg, Ca, Sr, Ba, and Msup(V) = Nb, Ta

Energy Technology Data Exchange (ETDEWEB)

Kemmler-Sack, S; Thumm, I; Herrmann, M [Tuebingen Univ. (Germany, F.R.). Lehrstuhl fuer Anorganische Chemie 2

1981-08-01

The hexagonal perovskites Ba/sub 3/Bsup(II)M/sub 2/sup(V)O/sub 9/ (Msup(V) = Nb, Ta) crystallize with Bsup(II) = Mg, Ca in a 3 L structure (sequence (c)/sub 3/) and Bsup(II) = Sr in the hexagonal BaTiO/sub 3/ type (6 L; sequence (hcc)/sub 2/) with an 1:2 order for the B and M ions. Intensity calculations for Ba/sub 3/SrNb/sub 2/O/sub 9/ and Ba/sub 3/SrTa/sub 2/O/sub 9/ gave in the space group P6/sub 3//mmc a refined, intensity related R' value of 8.4% (Nb) and 9.0% (Ta) respectively. For Bsup(II) = Ba the perovskite Ba/sub 3/BaTa/sub 2/O/sub 9/ has an orthorhombic distorted 6 L structure and forms with Ba/sub 3/SrTa/sub 2/O/sub 9/ a continuous series of mixed crystals (Ba/sub 3/Srsub(1-x)Basub(x)Ta/sub 2/O/sub 9/). In the system Ba/sub 3/Srsub(1-x)Basub(x)Nb/sub 2/O/sub 9/ the range of existence of the hexagonal BaTiO/sub 3/ type is confined to the Sr richer end. The pure Ba compound posesses a proper structure type (5 L: Ba/sub 5/BaNb/sub 3/vacantOsub(13.5)vacantsub(1.5)).

The Abundance of Mg in the Interstellar Medium

Science.gov (United States)

Fitzpatrick, Edward L.

1997-06-01

An empirical determination of the f-values of the far-UV Mg II λλ1239, 1240 lines is reported. The strong near-UV Mg II λλ2796, 2803 lines are generally highly saturated along most interstellar sight lines outside the local interstellar medium (ISM) and usually yield extremely uncertain estimates of Mg+ column densities in interstellar gas. Since Mg+ is the dominant form of Mg in the neutral ISM, and since Mg is expected to be a significant constituent of interstellar dust grains, the far-UV lines are critical for assessing the role of this important element in the ISM. This study consists of complete component analyses of the absorption along the lines of sight toward HD 93521 in the Galactic halo and ξ Persei and ζ Ophiuchi in the Galactic disk, including all four UV Mg+ lines and numerous other transitions. The three analyses yield consistent determinations of the λλ1239, 1240 f-values, with weighted means of (6.4 +/- 0.4) × 10-4 and (3.2 +/- 0.2) × 10-4, respectively. These results are a factor of ~2.4 larger than a commonly used theoretical estimate, and a factor of ~2 smaller than a recently suggested empirical revision. The effects of this result on gas- and dust-phase abundance measurements of Mg are discussed. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, under NASA contract NAS5-2655. This Letter is dedicated to the memory of Professor Lyman Spitzer Jr. He was a great guy.

The dust, nebular emission, and dependence on QSO radio properties of the associated Mg II absorption line systems

International Nuclear Information System (INIS)

Khare, Pushpa; Daniel, Vanden Berk; Rahmani, Hadi; York, Donald G.

2014-01-01

We studied dust reddening and [O II] emission in 1730 Mg II associated absorption systems (AAS; relative velocity with respect to QSOs, ≤3000 km s –1 ; in units of velocity of light, β, ≤0.01) with 0.4 ≤z abs ≤ 2 in the Sloan Digital Sky Survey DR7, focusing on their dependence on the radio and other QSO properties. We used control samples, several with matching radio properties, to show that (1) AAS in radio-detected (RD) QSOs cause 2.6 ± 0.2 times higher dust extinction than those in radio-undetected (RUD) ones, which in turn cause 2.9 ± 0.7 times the dust extinction in the intervening systems; (2) AAS in core-dominated QSOs cause 2.0 ± 0.1 times higher dust extinction than those in lobe-dominated QSOs; (3) the occurrence of AAS is 2.1 ± 0.2 times more likely in RD QSOs than in RUD QSOs and 1.8 ± 0.1 time more likely in QSOs having black holes with masses larger than 1.23 × 10 9 M ☉ than in those with lower-mass black holes; and (4) there is excess flux in [O II]λ3727 emission in the composite spectra of the AAS samples compared with those of the control samples, which is at the emission redshift. The presence of AAS enhances the O II emission from the active galactic nucleus and/or the host galaxy. This excess is similar for both RD and RUD samples and is 2.5 ± 0.4 times higher in lobe-dominated samples than in core-dominated samples. The excess depends on the black hole mass and Eddington ratio. All these point to the intrinsic nature of the AAS except for the systems with z abs > z em , which could be infalling galaxies.

Adsorption of Cd(II) and Cu(II) from aqueous solution by carbonate hydroxylapatite derived from eggshell waste

International Nuclear Information System (INIS)

Zheng Wei; Li Xiaoming; Yang Qi; Zeng Guangming; Shen Xiangxin; Zhang Ying; Liu Jingjin

2007-01-01

Carbonate hydroxylapatite (CHAP) synthesized by using eggshell waste as raw material has been investigated as metal adsorption for Cd(II) and Cu(II) from aqueous solutions. The effect of various parameters on adsorption process such as contact time, solution pH, amount of CHAP and initial concentration of metal ions was studied at room temperature to optimize the conditions for maximum adsorption. The results showed that the removal efficiency of Cd(II) and Cu(II) by CHAP could reach 94 and 93.17%, respectively, when the initial Cd(II) concentration 80 mg/L and Cu(II) 60 mg/L and the liquid/solid ratio was 2.5 g/L. The equilibrium sorption data for single metal systems at room temperature could be described by the Langmuir and Freundlich isotherm models. The highest value of Langmuir maximum uptake, (b), was found for cadmium (111.1 mg/g) and copper (142.86 mg/g). Similar Freundlich empirical constants, K, were obtained for cadmium (2.224) and copper (7.925). Ion exchange and surface adsorption might be involved in the adsorption process of cadmium and copper. Desorption experiments showed that CaCl 2 , NaCl, acetic acid and ultrasonic were not efficient enough to desorb substantial amount of metal ions from the CHAP. The results obtained show that CHAP has a high affinity to cadmium and copper

Quantitative Analysis of Mg in Pipeline Dirt Based on Laser-Induced Breakdown Spectroscopy

International Nuclear Information System (INIS)

Wang Shaolong; Wang Yangen; Chen Shanjun; Chen Qi

2015-01-01

In order to maintain the pipeline better and remove the dirt more effectively, it was necessary to analyze the contents of elements in dirt. Mg in soil outside of the pipe and the dirt inside of the pipe was quantitatively analyzed and compared by using the laser-induced breakdown spectroscopy (LIBS). Firstly, Mg was quantitatively analyzed on the basis of Mg I 285.213 nm by calibration curve for integrated intensity and peak intensity of the spectrum before and after subtracting noise, respectively. Then calibration curves on the basis of Mg II 279.553 nm and Mg II 280.270 nm were analyzed. The results indicated that it is better to use integrated intensity after subtracting noise of the spectrum line with high relative intensity to make the calibration curve. (paper)

In vivo and in vitro degradation comparison of pure Mg, Mg-10Gd and Mg-2Ag: a short term study

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I Marco

2017-02-01

Full Text Available The purpose of this study was to compare short term in vitro and in vivo biodegradation studies with low purity Mg (> 99.94 %, Mg-10Gd and Mg-2Ag designed for biodegradable implant applications. Three in vitro testing conditions were applied, using (i phosphate buffered saline (PBS, (ii Hank’s balanced salt solution (HBSS and (iii Dulbecco’s modified eagle medium (DMEM in 5 % CO2 under sterile conditions. Gas evolution and mass loss (ML were assessed, as well as the degradation layer, by elemental mapping and scanning electron microscopy (SEM. In vivo, implantations were performed on male Sprague-Dawley rats evaluating both, gas cavity volume and implant volume reduction by micro-computed tomography (µCT, 7 d after implantation. Samples were produced by casting, solution heat treatment and extrusion in disc and pin shape for the in vitro and in vivo experiments, respectively. Results showed that when the processing of the Mg sample varied, differences were found not only in the alloy impurity content and the grain size, but also in the corrosion behaviour. An increase of Fe and Ni or a large grain size seemed to play a major role in the degradation process, while the influence of alloying elements, such as Gd and Ag, played a secondary role. Results also indicated that cell culture conditions induced degradation rates and degradation layer elemental composition comparable to in vivo conditions. These in vitro and in vivo degradation layers consisted of Mg hydroxide, Mg-Ca carbonate and Ca phosphate.

Column dynamic studies and breakthrough curve analysis for Cd(II) and Cu(II) ions adsorption onto palm oil boiler mill fly ash (POFA).

Science.gov (United States)

Aziz, Abdul Shukor Abdul; Manaf, Latifah Abd; Man, Hasfalina Che; Kumar, Nadavala Siva

2014-01-01

This paper investigates the adsorption characteristics of palm oil boiler mill fly ash (POFA) derived from an agricultural waste material in removing Cd(II) and Cu(II) from aqueous solution via column studies. The performance of the study is described through the breakthrough curves concept under relevant operating conditions such as column bed depths (1, 1.5, and 2 cm) and influent metal concentrations (5, 10, and 20 mg/L). The Cd(II) and Cu(II) uptake mechanism is particularly bed depth- and concentration-dependant, favoring higher bed depth and lower influent metal concentration. The highest bed capacity of 34.91 mg Cd(II)/g and 21.93 mg Cu(II)/g of POFA was achieved at 20 mg/L of influent metal concentrations, column bed depth of 2 cm, and flow rate of 5 mL/min. The whole breakthrough curve simulation for both metal ions were best described using the Thomas and Yoon–Nelson models, but it is apparent that the initial region of the breakthrough for Cd(II) was better described using the BDST model. The results illustrate that POFA could be utilized effectively for the removal of Cd(II) and Cu(II) ions from aqueous solution in a fixed-bed column system.

Biosorption of Cd(II) and Zn(II) by nostoc commune: isotherm and kinetics studies

Energy Technology Data Exchange (ETDEWEB)

Morsy, Fatthy M. [Faculty of Science, Botany Department, Assiut University, Assiut (Egypt); Hassan, Sedky H.A. [Department of Biological Environment, Kangwon National University, Kangwon-do (Korea, Republic of); Koutb, Mostafa [Faculty of Science, Botany Department, Assiut University, Assiut (Egypt); Umm Al-Qura University, Faculty of Applied Science, Biology Department, Mecca (Saudi Arabia)

2011-07-15

In this study, Nostoc commune (cyanobacterium) was used as an inexpensive and efficient biosorbent for Cd(II) and Zn(II) removal from aqueous solutions. The effect of various physicochemical factors on Cd(II) and Zn(II) biosorption such as pH 2.0-7.0, initial metal concentration 0.0-300 mg/L and contact time 0-120 min were studied. Optimum pH for removal of Cd(II) and Zn(II) was 6.0, while the contact time was 30 min at room temperature. The nature of biosorbent and metal ion interaction was evaluated by infrared (IR) technique. IR analysis of bacterial biomass revealed the presence of amino, carboxyl, hydroxyl, and carbonyl groups, which are responsible for biosorption of Cd(II) and Zn (II). The maximum biosorption capacities for Cd(II) and Zn(II) biosorption by N. commune calculated from Langmuir biosorption isotherm were 126.32 and 115.41 mg/g, respectively. The biosorption isotherm for two biosorbents fitted well with Freundlich isotherm than Langmuir model with correlation coefficient (r{sup 2} < 0.99). The biosorption kinetic data were fitted well with the pseudo-second-order kinetic model. Thus, this study indicated that the N. commune is an efficient biosorbent for the removal of Cd(II) and Zn(II) from aqueous solutions. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Improved thermal stability of gas-phase Mg nanoparticles for hydrogen storage

NARCIS (Netherlands)

Krishnan, Gopi; Palasantzas, G.; Kooi, B. J.

2010-01-01

This work focuses on improving the thermal stability of Mg nanoparticles (NPs) for use in hydrogen storage. Three ways are investigated that can achieve this goal. (i) Addition of Cu prevents void formation during NP production and reduces the fast evaporation/voiding of Mg during annealing. (ii)

Mutation of Gly195 of the ChlH subunit of Mg-chelatase reduces chlorophyll and further disrupts PS II assembly in a Ycf48-deficient strain of Synechocystis sp. PCC 6803

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Tim Crawford

2016-07-01

Full Text Available Biogenesis of the photosystems in oxygenic phototrophs requires co-translational insertion of chlorophyll a. The first committed step of chlorophyll a biosynthesis is the insertion of a Mg2+ ion into the tetrapyrrole intermediate protoporphyrin IX, catalyzed by Mg-chelatase. We have identified a Synechocystis sp. PCC 6803 strain with a spontaneous mutation in chlH that results in a Gly195 to Glu substitution in a conserved region of the catalytic subunit of Mg-chelatase. Mutant strains containing the ChlH Gly195 to Glu mutation were generated using a two-step protocol that introduced the chlH gene into a putative neutral site in the chromosome prior to deletion of the native gene. The Gly195 to Glu mutation resulted in strains with decreased chlorophyll a. Deletion of the PS II assembly factor Ycf48 in a strain carrying the ChlH Gly195 to Glu mutation did not grow photoautotrophically. In addition, the ChlH-G195E:ΔYcf48 strain showed impaired PS II activity and decreased assembly of PS II centers in comparison to a ΔYcf48 strain. We suggest decreased chlorophyll in the ChlH-G195E mutant provides a background to screen for the role of assembly factors that are not essential under optimal growth conditions.

The dust, nebular emission, and dependence on QSO radio properties of the associated Mg II absorption line systems

Energy Technology Data Exchange (ETDEWEB)

Khare, Pushpa [CSIR Emeritus Scientist, IUCAA, Ganeshkhind, Pune 411007 (India); Daniel, Vanden Berk [Physics Department, St. Vincent College, Latrobe, PA 15650 (United States); Rahmani, Hadi [School of Astronomy, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); York, Donald G., E-mail: pushpakhare@gmail.com [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States)

2014-10-10

We studied dust reddening and [O II] emission in 1730 Mg II associated absorption systems (AAS; relative velocity with respect to QSOs, ≤3000 km s{sup –1}; in units of velocity of light, β, ≤0.01) with 0.4 ≤z {sub abs} ≤ 2 in the Sloan Digital Sky Survey DR7, focusing on their dependence on the radio and other QSO properties. We used control samples, several with matching radio properties, to show that (1) AAS in radio-detected (RD) QSOs cause 2.6 ± 0.2 times higher dust extinction than those in radio-undetected (RUD) ones, which in turn cause 2.9 ± 0.7 times the dust extinction in the intervening systems; (2) AAS in core-dominated QSOs cause 2.0 ± 0.1 times higher dust extinction than those in lobe-dominated QSOs; (3) the occurrence of AAS is 2.1 ± 0.2 times more likely in RD QSOs than in RUD QSOs and 1.8 ± 0.1 time more likely in QSOs having black holes with masses larger than 1.23 × 10{sup 9} M {sub ☉} than in those with lower-mass black holes; and (4) there is excess flux in [O II]λ3727 emission in the composite spectra of the AAS samples compared with those of the control samples, which is at the emission redshift. The presence of AAS enhances the O II emission from the active galactic nucleus and/or the host galaxy. This excess is similar for both RD and RUD samples and is 2.5 ± 0.4 times higher in lobe-dominated samples than in core-dominated samples. The excess depends on the black hole mass and Eddington ratio. All these point to the intrinsic nature of the AAS except for the systems with z {sub abs} > z {sub em}, which could be infalling galaxies.

Heavy Metals (Mg, Mn, Ni and Sn contamination in Soil Samples of Ahvaz II Industrial Estate of Iran in 2013

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Soheil l Sobhanardakani

2016-04-01

Full Text Available Background & Aims of the Study: Due to the rapid industrial development in Khuzestan province of Iran during recent years, this study was performed to analyze the variation of metals concentrations (Mg, Mn, Ni, and Sn in soil samples of Ahvaz II Industrial estate during the spring season of 2013. Materials & Methods: In this experimental study, 27 topsoil samples were collected from nine stations. The intensity of the soil contamination was evaluated, using a contamination factor (Cf and geo-accumulation index (I-geo. Results:  The mean soil concentrations (in mg kg-1 (dry weight were in ranged within 870-1144 (Mg, 188-300 (Mn, 93-199 (Ni and 9-15 (Sn. The data indicated that the I-geo value for all metals falls in class ‘1’. Also the Cf value for Mg and Mn falls in class ‘0’, the Cf value for Sn falls in class ‘1’ and the Cf value for Ni falls in the classes of ‘1’ and ‘2’. The result of the Pearson correlation showed that there were significant positive associations between all metals. Conclusions: According to the results which were achieved by a cluster analysis, there were significant positive associations among all metals based on Pearson correlation coefficient, especially between Ni and Sn; also both of them with Mn. Because the Ni originates from oil sources it can be resulted that Mn and Sn originate from oil sources, too. Therefore, industrial activities and exploitation of oil reservoirs are the main cause of pollution in that area. Also, it can be concluded that, with increasing the distance from the source of pollution, the accumulation of contaminants in the soil samples decreased.

Reduction in chlorhexidine efficacy against multi-drug-resistant Acinetobacter baumannii international clone II.

Science.gov (United States)

Hayashi, M; Kawamura, K; Matsui, M; Suzuki, M; Suzuki, S; Shibayama, K; Arakawa, Y

2017-03-01

Nosocomial infections caused by Acinetobacter baumannii international clone II (IC II) can cause severe clinical outcomes. Differential evaluation of bactericidal efficacy of chlorhexidine gluconate (CHX) and benzethonium chloride (BZT) disinfectants against IC II and non-IC II isolates. Minimum inhibitory concentrations (MICs) of CHX and BZT were determined for 137 A. baumannii IC II, 99 non-IC II and 69 non-baumannii isolates, further classified according to MIC values into disinfectant-reduced susceptible (DRS) and disinfectant-susceptible (DS) groups. Time-kill curves and minimum bactericidal concentrations (MBCs) were evaluated for representative isolates in each group. CHX and BZT MIC 90 s for IC II isolates were 100 and 175mg/L, respectively, but those for non-IC II and non-baumannii isolates were <100mg/L. Nevertheless, time-kill curves indicated that CHX and BZT reduced live bacterial cell number by 5 log 10 for IC II and non-IC II isolates within 30s when used at 1000mg/L, comparable to practical use concentrations. CHX MBC at 30s was 1000mg/L for IC II and non-IC II isolates, and was not influenced by addition of 3% bovine serum albumin (BSA); BZT MBC at 30s was 100mg/L without BSA and increased up to 500mg/L upon addition of BSA. No significant differences in BSA were found between DRS and DS isolates. CHX and BZT were effective against Acinetobacter spp. including IC II at a concentration of 1000mg/L and exposure for at least 30s, but their concentrations should be considered carefully to ensure sufficient effects in both clinical and healthcare settings. Copyright © 2016 The Healthcare Infection Society. Published by Elsevier Ltd. All rights reserved.

Biosorption of cadmium (II) and lead (II) from aqueous solutions using mushrooms: A comparative study

Energy Technology Data Exchange (ETDEWEB)

Vimala, R., E-mail: vimararagu@yahoo.co.in [School of Biotechnology, Chemical and Biomedical Engineering, VIT University, Vellore 632014, Tamil Nadu (India); Das, Nilanjana [School of Biotechnology, Chemical and Biomedical Engineering, VIT University, Vellore 632014, Tamil Nadu (India)

2009-08-30

Sorption capacity of oyster mushroom (Pleurotus platypus), button mushroom (Agaricus bisporus) and milky mushroom (Calocybe indica) were evaluated on biosorption of heavy metals, viz. cadmium (II) and lead (II) from aqueous solutions. The optimum sorption conditions were studied for each metal separately. The desired pH of the aqueous solution was found to be 6.0 for the removal of cadmium (II) and 5.0 for removal of lead (II) for all the mushrooms. The percent removal of both the metals was found to increase with the increase in biosorbent dosage and contact time. The fitness of the biosorption data for Langmuir and Freundlich adsorption models was investigated. It was found that biosorption of cadmium (II) and lead (II) ions onto the biomass of the three mushrooms were better suitable to Langmuir than Freundlich adsorption model. P. platypus showed the highest metal uptake potential for cadmium (q{sub max} 34.96 mg/g) whereas A. bisporus exhibited maximum potential for lead (q{sub max} 33.78 mg/g). Milky mushroom showed the lowest metal uptake capacity for both the metals. The present data confirms that mushrooms may be used as efficient biosorbent for the removal of cadmium (II) and lead (II) ions from aqueous solution.

Growth and characterization of ZnCdMgSe-based green light emitters and distributed Bragg reflectors towards II-VI based semiconductor disk lasers

International Nuclear Information System (INIS)

De Jesus, Joel; Gayen, Swapan K.; Garcia, Thor A.; Tamargo, Maria C.; Kartazaev, Vladimir; Jones, Brynmor E.; Schlosser, Peter J.; Hastie, Jennifer E.

2015-01-01

We report the structural and optical properties of molecular beam epitaxy grown II-VI semiconductor multiple quantum well (MQW) structures and distributed Bragg reflector (DBR) on InP substrates for application in developing optically-pumped semiconductor disk lasers (SDLs) operating in the green spectral range. One sample was grown directly on an InP substrate with an InGaAs buffer layer, while another had a 5-period ZnCdMgSe-based DBR grown on the InGaAs/InP substrate. X-ray diffraction and scanning electron microscopy measurements revealed sharp superlattice peaks and abrupt layer interfaces, while steady-state photoluminescence measurements demonstrated surface emission between 540-570 nm. Under pulsed excitation both samples exhibited features of amplified spontaneous emission (ASE) or stimulated emission, accompanied by luminescence lifetime shortening. The sample with the DBR showed higher surface luminescence and the onset of ASE at lower pump power. To further explore the design and performance of a ZnCdMgSe-based DBR, a 20-period DBR was grown and a reflectivity of 83% was obtained at ∝560 nm. We estimate that a DBR with ∝40 periods would be needed for optimal performance in a SDL using these materials. These results show the potential of II-VI MQW structures on InP substrates for the development of SDLs operational in the green-yellow wavelength range. (copyright 2015 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Arsenic removal with iron(II) and iron(III) in waters with high silicate and phosphate concentrations.

Science.gov (United States)

Roberts, Linda C; Hug, Stephan J; Ruettimann, Thomas; Billah, Morsaline; Khan, Abdul Wahab; Rahman, Mohammad Tariqur

2004-01-01

Arsenic removal by passive treatment, in which naturally present Fe(II) is oxidized by aeration and the forming iron(III) (hydr)oxides precipitate with adsorbed arsenic, is the simplest conceivable water treatment option. However, competing anions and low iron concentrations often require additional iron. Application of Fe(II) instead of the usually applied Fe(III) is shown to be advantageous, as oxidation of Fe(II) by dissolved oxygen causes partial oxidation of As(III) and iron(III) (hydr)oxides formed from Fe(II) have higher sorption capacities. In simulated groundwater (8.2 mM HCO3(-), 2.5 mM Ca2+, 1.6 mM Mg2+, 30 mg/L Si, 3 mg/L P, 500 ppb As(III), or As(V), pH 7.0 +/- 0.1), addition of Fe(II) clearly leads to better As removal than Fe(III). Multiple additions of Fe(II) further improved the removal of As(II). A competitive coprecipitation model that considers As(III) oxidation explains the observed results and allows the estimation of arsenic removal under different conditions. Lowering 500 microg/L As(III) to below 50 microg/L As(tot) in filtered water required > 80 mg/L Fe(III), 50-55 mg/L Fe(II) in one single addition, and 20-25 mg/L in multiple additions. With As(V), 10-12 mg/L Fe(II) and 15-18 mg/L Fe(III) was required. In the absence of Si and P, removal efficiencies for Fe(II) and Fe(III) were similar: 30-40 mg/L was required for As(II), and 2.0-2.5 mg/L was required for As(V). In a field study with 22 tubewells in Bangladesh, passive treatment efficiently removed phosphate, but iron contents were generally too low for efficient arsenic removal.

Ultraviolet technology II; Proceedings of the Meeting, Orlando, FL, Apr. 4, 5, 1988

International Nuclear Information System (INIS)

Huffman, R.E.

1988-01-01

The conference presents papers on the chemical analysis of UV rocket plume signatures, the determination of daytime midlatitude electron density profiles from satellite UV and in-situ data, and the application of CCD detectors to UV imaging from a spinning satellite. Other topics include a middle atmosphere high-resolution spectrograph, very large format pulse-counting UV detectors, optical filters for high-resolution UV imaging systems, and synthetic dayglow spectra and the Rayleigh scattering background from the FUV to the visible. Consideration is also given to image motion compensation using a photon-counting UV/visible detector, UV/ozone removal of contaminants in spacecraft environments, and decoding techniques for fine-fine geometry multianode microchannel arrays

Biorsopsi Ion Logam Zink (II dalam Larutan Menggunakan Daun Kari (Murraya Koenigii

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Bhayu Gita Bhernama

2017-06-01

Full Text Available Penyerapan ion logam Zn (II menggunakan daun kari (murraya koenigii telah dilakukan, Penelitian ini bertujuan untuk menentukan kadar ion logam Zn (II yang dapat diserap oleh daun kari (murraya koenigii. Kemampuan daun kari untuk menyerap ion logam Zn (II telah dievaluasi dengan variasi pH larutan, kosentrasi, ukuran partikel berat biomaterial. Kadar ion logam yang terserap diukur menggunakan spektrofotometer serapan atom (SSA. Hasil penelitian menunjukan kondisi optimum penyerapan ion logam Zn 9II menggunakan daun kari dengan pH 5 kapasitas penyerapan 0,611 mg/g, ukuran partikel 150 µm kapasitas penyerapan 0,689 mg/g, konsentrasi 50 ppm dengan kapasitas penyerapan 0,443 mg/g dan berat material 0,5 g kapasitas penyerapan 1,505 mg/g. Berdasarkan persamaan isoterm Langmuir didapatkan kapasitas penyerapan maksimum Qmax -0,127. Hasil analisis FTIR memperlihatkan adanya gugus hidroksil yang dapat mengikat ion logam Zn (II. Kata kunci : logam berat Zn (II, penyerapan, daun kari

Modeling Fe II Emission and Revised Fe II (UV) Empirical Templates for the Seyfert 1 Galaxy I Zw 1

Science.gov (United States)

Bruhweiler, F.; Verner, E.

2008-03-01

We use the narrow-lined broad-line region (BLR) of the Seyfert 1 galaxy, I Zw 1, as a laboratory for modeling the ultraviolet (UV) Fe II 2100-3050 Å emission complex. We calculate a grid of Fe II emission spectra representative of BLR clouds and compare them with the observed I Zw 1 spectrum. Our predicted spectrum for log [nH/(cm -3) ] = 11.0, log [ΦH/(cm -2 s-1) ] = 20.5, and ξ/(1 km s-1) = 20, using Cloudy and an 830 level model atom for Fe II with energies up to 14.06 eV, gives a better fit to the UV Fe II emission than models with fewer levels. Our analysis indicates (1) the observed UV Fe II emission must be corrected for an underlying Fe II pseudocontinuum; (2) Fe II emission peaks can be misidentified as that of other ions in active galactic nuclei (AGNs) with narrow-lined BLRs possibly affecting deduced physical parameters; (3) the shape of 4200-4700 Å Fe II emission in I Zw 1 and other AGNs is a relative indicator of narrow-line region (NLR) and BLR Fe II emission; (4) predicted ratios of Lyα, C III], and Fe II emission relative to Mg II λ2800 agree with extinction corrected observed I Zw 1 fluxes, except for C IV λ1549 (5) the sensitivity of Fe II emission strength to microturbulence ξ casts doubt on existing relative Fe/Mg abundances derived from Fe II (UV)/Mg II flux ratios. Our calculated Fe II emission spectra, suitable for BLRs in AGNs, are available at http://iacs.cua.edu/people/verner/FeII. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 05-26555.

Detection of 12 micron Mg I and OH lines in stellar spectra

Science.gov (United States)

Jennings, D. E.; Deming, D.; Wiedemann, G. R.; Keady, J. J.

1986-01-01

Infrared lines of Mg I and OH have been detected in stellar spectra near 12.3 microns. The Mg I 7i-6h transition was seen in Alpha Ori and Alpha Tau, and the R2e(23.5) and R1f(24.5) transitions of OH were seen in Alpha Ori. All lines appear in absorption, in contrast to the solar spectrum where the Mg I line shows a prominent emission core. The lack of emission in these low surface gravity stars is due to a greatly reduced volume recombination rate for the high-n states of Mg I, which is not fully compensated by the increased chromospheric scale height. The OH equivalent widths are sensitive to the temperature structure of the upper photosphere of Alpha Ori, and they indicate that the photosphere near tau 5000 of about 10 to the -5th is approximately 100 K hotter than is given by flux constant models. The OH measurements agree more closely with the 1981 semiemprical model of Basri, Linsky, and Eriksson (1981), which is based on Ca II and Mg II ultraviolet features.

Study of physicochemical parameters for cadmium (II) and mercury (II) phytoremediation using the specie Eichhornia Crassipes (water hyacinth)

International Nuclear Information System (INIS)

Poma Llantoy, Victor R.; Valderrama Negron, Ana C.

2014-01-01

In this work, the studies were performed to measure the sorption capacity of metal ions Cd (II) and Hg (II) using the specie Eichhornia crassipes (water hyacinth). This study includes assays where the nutrient concentration, the pH and the metal ion concentration were optimized. These tests were carried out at room temperature and with aqueous solutions of Cd (II), Hg (II), in which the samples of Eichhornia crassipes were placed. To confirm the removal of these metals, the waste solutions after the treatment with the Water Hyacinth species were treated using the method APHA 3030-e. However, Eichhornia crassipes samples were treated using the EPA 200.3 method. The concentration of Cd (II) was determined by an ICP-OES spectrometer and Hg (II), by an atomic absorption spectrophotometer. The results showed: Optimal dosage 1 mL of A and 0,5 mL of B, optimum pH 5, optimum concentration of Cd (II) and Hg (II) 5 mg/L for each ion. With these parameters, it was started the removal of 5 mg/L of the metal ions contained in 1 L of solution. Being the percentages of sorption 16,56% for Cd (II) and 15,6% for Hg (II) after a period of 7 days. (author)

Adsorption study of cadmium (II) and lead (II) on radish peels

International Nuclear Information System (INIS)

Anwar, J.; Shafique, U.; Salman, M.; Zaman, W.; Memoona, M.

2009-01-01

The removal efficiency of heavy metals like Cd(II) and Pb(II) from aqueous solutions by adsorption on Raphanus sativus (Radish peels) has been studied. The effects of time, pH, concentration of adsorbent and agitation speed on adsorption have been evaluated. It is found that radish peels powder has high removal efficiency for both the metals. Batch adsorption study has shown that Cd(II) and Pb(II) has been removed up to 88% and 86% respectively. Adsorption equilibriums for both metals have been described by the Langmuir isotherm. The maximum amount of heavy metals (Q ) adsorbed at max equilibrium were 7.5 and 1.23 mg/g for Cd(II) and Pb(II) respectively as evaluated by Langmuir isotherm. It is concluded that waste materials like radish peels can be used for removal of heavy metals from aqueous streams. (author)

Air permeability of the artificially synthesized Zn-Al-Mg alloy rusts

International Nuclear Information System (INIS)

Ishikawa, Tatsuo; Ueda, Masato; Kandori, Kazuhiko; Nakayama, Takenori

2007-01-01

The rust particles of Zn-Al-Mg alloys were synthesized from aqueous solutions dissolving ZnCl 2 , AlCl 3 , and MgCl 2 at different atomic ratios of the metal ions. The crystal phase and particle morphology of the products depended on the composition of the starting solutions. The compactness of the layers of the products was estimated by measuring their air permeability. The layer of mixed metal hydroxide chloride formed at Zn:Al:Mg = 1:1:1 showed a highest compactness, that was ascribed to the preferred orientation of the fine plate particles. The addition of Mg(II) made plate particles smaller to give more compact layers

Thermodynamic Modeling of Poorly Complexing Metals in Concentrated Electrolyte Solutions: An X-Ray Absorption and UV-Vis Spectroscopic Study of Ni(II) in the NiCl2-MgCl2-H2O System

Science.gov (United States)

Zhang, Ning; Brugger, Joël; Etschmann, Barbara; Ngothai, Yung; Zeng, Dewen

2015-01-01

Knowledge of the structure and speciation of aqueous Ni(II)-chloride complexes is important for understanding Ni behavior in hydrometallurgical extraction. The effect of concentration on the first-shell structure of Ni(II) in aqueous NiCl2 and NiCl2-MgCl2 solutions was investigated by Ni K edge X-ray absorption (XAS) and UV-Vis spectroscopy at ambient conditions. Both techniques show that no large structural change (e.g., transition from octahedral to tetrahedral-like configuration) occurs. Both methods confirm that the Ni(II) aqua ion (with six coordinated water molecules at R Ni-O = 2.07(2) Å) is the dominant species over the whole NiCl2 concentration range. However, XANES, EXAFS and UV-Vis data show subtle changes at high salinity (> 2 mol∙kg-1 NiCl2), which are consistent with the formation of small amounts of the NiCl+ complex (up to 0.44(23) Cl at a Ni-Cl distance of 2.35(2) Å in 5.05 mol∙kg-1 NiCl2) in the pure NiCl2 solutions. At high Cl:Ni ratio in the NiCl2-MgCl2-H2O solutions, small amounts of [NiCl2]0 are also present. We developed a speciation-based mixed-solvent electrolyte (MSE) model to describe activity-composition relationships in NiCl2-MgCl2-H2O solutions, and at the same time predict Ni(II) speciation that is consistent with our XAS and UV-Vis data and with existing literature data up to the solubility limit, resolving a long-standing uncertainty about the role of chloride complexing in this system. PMID:25885410

Solid solubility of MgO in the calcium silicates of portland clinker. The effect of CaF2

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Puertas, F.

1992-03-01

Full Text Available The solid solubility of MgO in the calcium silicates of portland clinker has been determined by XRD and XDS. The influence that the presence of CaF2 has on said solubility has also been verified. The solid solution limit of MgO in C3S at 1275 ºC lies at about 1.0% wt, where the triclinic form II stabilizes. The presence of CaF2 does not alter the maximum value of the MgO solubilized in that silicate, although there does take place the stabilization of the triclinic polymorph II at lower MgO contents (between 0.3 - 0.6% wt. The maximum amount of solubilized MgO in βC2 at 1.050 ºC lies around 0.5% wt. This value does not change by the presence of CaF2.Se ha determinado por DRX y EDX la solubilidad sólida del MgO en los silicatos cálcicos del clínker portland. Se ha comprobado, así mismo la influencia que sobre dicha solubilidad tiene la presencia de CaF2. El límite de disolución sólida del MgO en el C3S a 1.275º C se sitúa alrededor del 1,0% en peso, estabilizándose la forma triclínica II. La presencia de CaF2 no altera el valor máximo de MgO solubilizado en este silicato, aunque si se produce la estabilización del polimorfo triclínico II a contenidos menores de MgO (entre 0,3 – 0,6% en peso. La cantidad máxima de MgO solubilizado en e/ βC2S a 1.050 ºC se sitúa en torno al 0,5% en peso. Este valor no se ve modificado por la presencia de CaF2.

Assessment of the excitation temperatures and Mg II:I line ratios of the direct current (DC) arc source for the analysis of radioactive materials

International Nuclear Information System (INIS)

Manard, B.T.; Matonic, John; Montoya, Dennis; Jump, Robert; Castro, Alonso; Ning Xu

2017-01-01

The direct current (DC) arc plasma has been assessed with an emphasis on excitation temperature (T_e_x_e) and ionization/excitation efficiency by monitoring magnesium ionic:atomic ratios (Mg II:I). The primary goal is to improve the analytical performance of the DC arc instrumentation such that more sensitive and reproducible measurements can be achieved when analyzing trace impurities in nuclear materials. Due to the variety of sample types requiring DC arc analysis, an understanding of the plasma's characteristics will significantly benefit the experimental design when moving forward with LANL's capabilities for trace metal analysis of plutonium metals. (author)

Removal of Cu(II) in water by polymer enhanced ultrafiltration: Influence of polymer nature and pH.

Science.gov (United States)

Kochkodan, Olga D; Kochkodan, Viktor M; Sharma, Virender K

2018-01-02

This study presents an efficient removal of Cu(II) in water using the polymer enhanced ultrafiltration (PEUF) method. Polymer of different molecular weight (MW) (polyethyleneimine (PEI), sodium lignosulfonates (SLS) and dextrans) were investigated to evaluate efficiency in removal of Cu(II) in water by the PEUF method. The decomposition of Cu(II)-polymer complex was also evaluated in order to reuse polymers. Cu(II) complexation depends on the MW of chelating polymer and the pH of feed solution. It was found that the Cu(II) rejection increased with the polymer dosage with high removal of Cu(II) when using PEI and SLS at a 10:20 (mg/mg) ratio ([Cu(II)]:[polymer]). It was found that the maximum chelating capacity was 15 mg of Cu(II) per 20 mg of PEI. The Cu(II)-PEI complex could be decomposed by acid addition and the polymer could be efficiently reused with multiple complexation-decomplexation cycles. A conceptual flow chart of the integrated process of efficient removal of Cu(II) by PEUF method is suggested.

Formation of Fe/mg Smectite Under Acidic Conditions from Synthetic Adirondack Basaltic Glass: an Analog to Fe/mg Smectite Formation on Mars

Science.gov (United States)

Sutter, B.; Peretyazhko, T.; Morris, R. V.; Ming, D. W.

2014-01-01

Smectite has been detected as layered material hundreds of meters thick, in intracrater depositional fans, in plains sediments, and deposits at depth on Mars. If early Mars hosted a dense CO2 atmosphere, then extensive carbonate should have formed in the neutral/alkaline conditions expected for smectite formation. However, large carbonate deposits on Mars have not been discovered. Instead of neutral to moderately alkaline conditions, early Mars may have experienced mildly acidic conditions that allowed for Fe/Mg smectite formation but prevented widespread carbonate formation. The objective of this work is to demonstrate that Fe(II)/Mg saponite and nontronite can form in mildly acidic solutions (e.g., pH 4). Synthetic basaltic glass (Smectite was confirmed as the phyllosilicate after treatments with glycerol and KCl and heating to 550 C. Trioctahedral saponite was confirmed by the presence of a 4.58 to 4.63 Angstroms (02l) and 1.54Angstroms (060) peaks. Saponite concentration was highest, as indicated by XRD peak intensity, in the 10 mM Mg treatment followed by the 0 mM and then 10 mM Fe(II) treatments. This order of sapontite concentration suggests that Fe(II) additions may have a role in slowing the kinetics of saponite formation relative to the other treatments. Nontronite synthesis was attempted by exposing Adirondack basaltic glass to pH 4 oxic solutions (without N2 purge) at 200 C for 14 days. X-ray diffraction analysis indicated that mixtures of trioctahedral (saponite) and dioctahedral (nontronite) may have formed in these experiments based on the 02l and 060 peaks. Moessbauer analysis coupled with future experiments are planned to verify if nontronite can be formed under mildly acidic and oxic conditions. Results of this work demonstrate that acidic conditions could have occurred on an early Mars, which allowed for smectite formation but inhibited carbonate formation.

Density functional theory (DFT) study on the hydrolysis behavior of degradable Mg/Mg alloys for biomedical applications

Science.gov (United States)

Nezafati, Marjan

Magnesium-based (Mg and/or Mg alloys) materials possess many advantageous physicochemical/biological characteristics such as good biocompatibility and similarity of the mechanical properties to the human bone tissue, which renders this material a promising candidate for the biomedical and implant applications. One of the most attractive features of Mg-based materials is the degradability in the physiological environment. With the burst of research on the biodegradable materials for the healthcare device applications, Mg and its alloys attracted a strong attention in the bioengineering field in recent years. However, the major limitation of applying Mg-based materials to biomedical applications is the fast degradation/corrosion rate with regards to the healing process time-span. In the present thesis, an atomistic model employing the density-functional theory (DFT) has been developed to study the hydrolysis process by understanding the influences of commonly used alloying elements (zinc (Zn), calcium (Ca), aluminum (Al), and yttrium (Y)) and the crystallographic orientation of the dissolution surfaces (basal (0001), prism (1010), and pyramidal (1011) planes) on the corrosion behavior. These parameters are known to strongly impact the initial hydrolysis phenomena of Mg-based materials. To develop the atomistic computational model, we have implemented the Dmol3 software package in conjunction with PBE (Perdew, Burke and Ernzerhof) correlation energy functional in the GGA (generalized gradient approximation) scheme. Throughout the thesis, we performed three sets of calculations, i) surface energy, ii) dissolution potential, and iii) water adsorption computations, to examine the hydrolysis mechanism and the subsequent corrosion/degradation of Mg/Mg alloys. The total energy changes of various Mg-based systems in different conditions for these surface energies, dissolution behavior, and tendency of the system for adsorbing the water molecule were quantified. The results

Perbandingan Pemberian Ondansetron 8 mg dengan Tramadol 1 mg/ kgBB Intravena untuk Mencegah Menggigil Pascaanestesi Umum pada Operasi Mastektomi Radikal atau Modifikasi

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Mirza Oktavian

2014-04-01

Full Text Available ost anesthetic shivering is a common complication of general anesthesia and preventable with several types of drugs. The aim of this study was to compare the efficacy of intravenous 8mg ondansetron versus tramadol 1 mg/kgBW in preventing post anesthetic shivering after general anesthesia. The research is a prospective, randomized double-blind controlled study involving 38 female patients aged 30–65 years at Dr. Hasan Sadikin Hospital Bandung period March–April 2012, American Society of Anesthesiologist (ASA physical status I–II, who underwent radical or modified mastectomy. Subjects were randomly divided into two groups. One group was given ondansetron 8 mg and the other group was given tramadol 1 mg/kgBW before surgical wound closure. Research results showed that incidence of post anesthetic shivering was less on tramadol group (15.8% compared to ondansetron (52.6% group, which is statistically significant (p<0.05. In conclusion, administration of tramadol 1 mg/kgBW intravenously is more effective in preventing post anesthetic shivering in radical or modified mastectomy.

Karakterisasi Adsorben dari Kulit Manggis dan Kinerjanya pada Adsorpsi Logam Pb(II dan Cr(VI - (Adsorbent Characterization from Mangosteen Peel and Its Adsorption Performance on Pb(II and Cr(VI

Directory of Open Access Journals (Sweden)

Ulfa Haura

2017-06-01

Full Text Available The usage of biomass waste-based adsorbent for the adsorption of hazardous metal in wastewater is not only reducing waste but also lowering adsorbent price. This research aims to study the characteristics of adsorbent from mangosteen peel (Garcinia Mangostana L. and activated charcoal from mangosteen peel, also to compare the adsorption performance on metal ion Pb(II and Cr(VI. Synthetic wastewater used from a solution of Pb(NO32 and K2Cr2O7 with variations in initial concentration of 20, 40, 80, 100 and 200 mg/L. Adsorption performed at pH 5, ratio of adsorbent and waste solution 1/200 (w/v, 60 rpm, 0.5 gs nano-sized adsorbent. Characterization using SEM, FTIR and SEM-EDS showed that both adsorbents characteristics met the requirements of SNI 06-3730-1995. The highest adsorption capacity of activated carbon to adsorb Pb(II and Cr(VI were 38.543 mg/g and 36.838 mg/g while biosorbent adsorb Pb(II and Cr(VI respectively 3.98 mg/g and 36.12 mg/g.Keywords: adsorption, biosorbent, Cr(VI, mangosteen peel, Pb(IIABSTRAKPenggunaan adsorben berbasis limbah biomassa untuk adsorpsi kandungan logam berbahaya dari limbah cair industri selain dapat mengurangi limbah juga dapat menekan harga jual adsorben. Penelitian ini bertujuan untuk mempelajari karakteristik adsorben yang terbuat dari limbah kulit manggis (Garcinia mangostana L. dan arang aktif dari limbah kulit manggis serta membandingkan kinerja kedua jenis adsorben tersebut pada proses adsorpsi ion logam Pb(II dan Cr(VI. Limbah sintetis yang digunakan berupa ion dari Pb(II dan Cr(VI dari larutan Pb(NO32 dan K2Cr2O7 dengan variasi konsentrasi awal 20, 40, 80, 100 dan 200 mg/L. Proses adsorpsi dilakukan pada pH 5, rasio perbandingan berat adsorben dan volume larutan limbah 1:200, kecepatan pengadukan 60 rpm, adsorben berukuran nano dengan berat adsorben 0,5 g. Masing-masing adsorben dikarakterisasi menggunakan SEM untuk mengetahui sturktur morfologi, FTIR untuk mengetahui gugus fungsi dan SEM-EDS untuk

Enhanced mechanical properties of an Al–Si–Cu–Mg alloy at 300 °C: Effects of Mg and the Q-precipitate phase

International Nuclear Information System (INIS)

Farkoosh, A.R.; Pekguleryuz, M.

2015-01-01

Strategies to improve the strength of Al–Si alloys at elevated temperatures can follow two routes: (i) improving the age-hardening behavior and/or (ii) producing effective dispersoid strengthening. In this study, the influence of Mg (in the range of 0.3–0.7 wt%) on the precipitation characteristics and mechanical properties of the Al–7Si–0.5Cu–(Mg) alloy was investigated. Thermodynamic calculations were performed via the CALPHAD method which showed that Q-Al 5 Mg 8 Cu 2 Si 6 is the main thermodynamically stable precipitate at 300 °C. The calculations were validated by transmission electron microscopy and differential scanning calorimetry analyses. Increasing the Mg level from 0.3 wt% to the maximum solubility limit of ∼0.5 wt% increased the amount of the Q-Al 5 Mg 8 Cu 2 Si 6 precipitates at 300 °C by ∼60 wt% and significantly improved the tensile strength and creep resistance at the expense of some ductility. Mg in excess of the solubility limit was seen to remain within the microstructure in the form of the large π-Al 8 FeMg 3 Si 6 and β-Mg 2 Si intermetallics after solution treatment at 530 °C. Cracking of the brittle π-Al 8 FeMg 3 Si 6 intermetallics during deformation was accounted for the decreased ductility of the alloys at high Mg levels. It is concluded that the Mg level can be increased to 0.5 wt% in the A–7Si–0.5Cu alloys to improve strength. However, for elevated temperature applications in which both strength and ductility are required (e.g. Diesel engine), modification of the π-Al 8 FeMg 3 Si 6 intermetallics would be required to improve the ductility of the alloys with high Mg contents

Simultaneous determination of Hg(II)-Ag(I)-Cd(II) by conductometric titration using the formation of ternary complex

International Nuclear Information System (INIS)

Hayashida, Ichiro; Yoshida, Hitoshi; Taga, Mitsuhiko; Hikime, Seiichiro

1979-01-01

A conductometric determination of Hg(II), Ag(I) and Cd(II) was carried out by using the insoluble ternary complex formation of the metal ions with iodide ion in the presence of 1,10-phenanthroline (phen). Recommended procedure is as follows; An aliquot of sample solution containing (14 -- 29) mg of Hg(II), (8 -- 16) mg of Ag(I), and (9 -- 17) mg of Cd(II) transfered into a 100 ml beaker. Add to acetate buffer and stoichiometric amounts of phen (40% ethanol-water solution). Amounts of nitrate ion which was estimated separately by other titration with 0.1 M Ag(phen) 2 complex (40% ethanol-water solution) are adjusted in the range of (4.0 -- 6.0) mM. The sample solution is titrated with 0.1 M KI standard solution at the rate of 0.20 ml/min or less. The titration curve showed three end-points corresponding to the formation of (1) Hg(phen) 2 I 2 , (2) Ag(phen)I, and (3) Cd(phen) 2 I 2 . The relative standard deviation was less than 0.8%, when the pH value was controlled at 4.0 -- 4.5 (acetate buffer) and the nitrate concentration was adjusted in the range of (4.0 -- 6.0)mM. The effect of diverse ions on the determination was also investigated in detail. (author)

Anoxic and Oxic Oxidation of Rocks Containing Fe(II)Mg-Silicates and Fe(II)-Monosulfides as Source of Fe(III)-Minerals and Hydrogen. Geobiotropy.

Science.gov (United States)

Bassez, Marie-Paule

2017-12-01

In this article, anoxic and oxic hydrolyses of rocks containing Fe (II) Mg-silicates and Fe (II)-monosulfides are analyzed at 25 °C and 250-350 °C. A table of the products is drawn. It is shown that magnetite and hydrogen can be produced during low-temperature (25 °C) anoxic hydrolysis/oxidation of ferrous silicates and during high-temperature (250 °C) anoxic hydrolysis/oxidation of ferrous monosulfides. The high-T (350 °C) anoxic hydrolysis of ferrous silicates leads mainly to ferric oxides/hydroxides such as the hydroxide ferric trihydroxide, the oxide hydroxide goethite/lepidocrocite and the oxide hematite, and to Fe(III)-phyllosilicates. Magnetite is not a primary product. While the low-T (25 °C) anoxic hydrolysis of ferrous monosulfides leads to pyrite. Thermodynamic functions are calculated for elementary reactions of hydrolysis and carbonation of olivine and pyroxene and E-pH diagrams are analyzed. It is shown that the hydrolysis of the iron endmember is endothermic and can proceed within the exothermic hydrolysis of the magnesium endmember and also within the exothermic reactions of carbonations. The distinction between three products of the iron hydrolysis, magnetite, goethite and hematite is determined with E-pH diagrams. The hydrolysis/oxidation of the sulfides mackinawite/troilite/pyrrhotite is highly endothermic but can proceed within the heat produced by the exothermic hydrolyses and carbonations of ferromagnesian silicates and also by other sources such as magma, hydrothermal sources, impacts. These theoretical results are confirmed by the products observed in several related laboratory experiments. The case of radiolyzed water is studied. It is shown that magnetite and ferric oxides/hydroxides such as ferric trihydroxide, goethite/lepidocrocite and hematite are formed in oxic hydrolysis of ferromagnesian silicates at 25 °C and 350 °C. Oxic oxidation of ferrous monosulfides at 25 °C leads mainly to pyrite and ferric oxides/hydroxides such as

Thermically stimulated exoelectronic emissions and thermoluminescence of MgO

International Nuclear Information System (INIS)

Chubaci, J.F.D.

1987-01-01

In this work, studies were performed on the following topics: i) thermically stimulated exoelectronic emission (TSEE) in pure MgO single crystals ion implanted, submitted to thermal treatment with fast on slow cooling and water adsorption; ii) ultraviolet light effect on TSEE; iii) thermoluminescent emission; iv) crystallization of FeCoB amorphous alloys. (A.C.A.S.) [pt

Biosorption of Cd(II), Ni(II) and Pb(II) from aqueous solution by dried biomass of aspergillus niger: application of response surface methodology to the optimization of process parameters

Energy Technology Data Exchange (ETDEWEB)

Amini, Malihe; Younesi, Habibollah [Department of Environmental Science, Faculty of Natural Resources and Marine Sciences, Tarbiat Modares University, Noor (Iran)

2009-10-15

In this study, the biosorption of Cd(II), Ni(II) and Pb(II) on Aspergillus niger in a batch system was investigated, and optimal condition determined by means of central composite design (CCD) under response surface methodology (RSM). Biomass inactivated by heat and pretreated by alkali solution was used in the determination of optimal conditions. The effect of initial solution pH, biomass dose and initial ion concentration on the removal efficiency of metal ions by A. niger was optimized using a design of experiment (DOE) method. Experimental results indicated that the optimal conditions for biosorption were 5.22 g/L, 89.93 mg/L and 6.01 for biomass dose, initial ion concentration and solution pH, respectively. Enhancement of metal biosorption capacity of the dried biomass by pretreatment with sodium hydroxide was observed. Maximal removal efficiencies for Cd(II), Ni(III) and Pb(II) ions of 98, 80 and 99% were achieved, respectively. The biosorption capacity of A. niger biomass obtained for Cd(II), Ni(II) and Pb(II) ions was 2.2, 1.6 and 4.7 mg/g, respectively. According to these observations the fungal biomass of A. niger is a suitable biosorbent for the removal of heavy metals from aqueous solutions. Multiple response optimization was applied to the experimental data to discover the optimal conditions for a set of responses, simultaneously, by using a desirability function. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

Sequestration of chelated copper by structural Fe(II): Reductive decomplexation and transformation of Cu{sup II}-EDTA

Energy Technology Data Exchange (ETDEWEB)

He, Hongping [State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science & Engineering, Tongji University, Shanghai 200092 (China); Wu, Deli, E-mail: wudeli@tongji.edu.cn [State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science & Engineering, Tongji University, Shanghai 200092 (China); Zhao, Linghui [State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science & Engineering, Tongji University, Shanghai 200092 (China); Luo, Cong [School of Civil and Environmental Engineering, Georgia Institute of Technology, GA 30332 (United States); Dai, Chaomeng; Zhang, Yalei [State Key Laboratory of Pollution Control and Resources Reuse, School of Environmental Science & Engineering, Tongji University, Shanghai 200092 (China)

2016-05-15

Highlights: • Structural Fe(II) was found to reveal high sequestration potential in various chelated copper. • Chelated copper was reduced to Cu(0) and Cu{sub 2}O by =Fe(II), whcih was oxidized to Fe{sub 2}O{sub 3}·H{sub 2}O. • Both electron transfer and surface =Fe(II) were found to be crucial during chelated copper reduction. • The indispensible role of reductive decomplexation was identified in chelated copper sequestration. - Abstract: Chelated coppers, such as Cu{sup II}-EDTA, are characteristically refractory and difficult to break down because of their high stability and solubility. Cu{sup II}–EDTA sequestration by structural Fe(II) (=Fe(II)) was investigated intensively in this study. Up to 101.21 mgCu(II)/gFe(II) was obtained by =Fe(II) in chelated copper sequestration under near neutral pH condition (pH 7.70). The mechanism of Cu{sup II}-EDTA sequestration by =Fe(II) was concluded as follows: 3Cu{sup II}–EDTA + 7=Fe(II) + 9H{sub 2}O → Cu(0) ↓ + Cu{sub 2}O ↓ (the major product) + 2Fe{sub 2}O{sub 3}·H{sub 2}O ↓ + 3Fe{sup II}–EDTA +14H{sup +} Novel results strongly indicate that Cu{sup II} reductive transformation induced by surface =Fe(II) was mainly responsible for chelated copper sequestration. Cu(0) generation was initially facilitated, and subsequent reduction of Cu(II) into Cu(I) was closely combined with the gradual increase of ORP (Oxidation-Reduction Potential). Cu-containing products were inherently stable, but Cu{sub 2}O would be reoxidized to Cu(II) with extra-aeration, resulting in the release of copper, which was beneficial to Cu reclamation. Concentration diminution of Cu{sup II}–EDTA within the electric double layer and competitive adsorption were responsible for the negative effects of Ca{sup 2+}, Mg{sup 2+}. By generating vivianite, PO{sub 4}{sup 3−} was found to decrease surface =Fe(II) content. This study is among the first ones to identify the indispensible role of reductive decomplexation in chelated copper

Synthesis of nanometer-sized fayalite and magnesium-iron(II) mixture olivines

Energy Technology Data Exchange (ETDEWEB)

Qafoku, Odeta; Ilton, Eugene S.; Bowden, Mark E.; Kovarik, Libor; Zhang, Xin; Kukkadapu, Ravi K.; Engelhard, Mark H.; Thompson, Christopher J.; Schaef, Herbert T.; McGrail, Bernard Peter; Rosso, Kevin M.; Loring, John S.

2018-04-01

Olivines are divalent orthosilicates with important geologic, biological, and industrial significance and are typically comprised of mixtures of Mg2+ and Fe2+ ranging from forsterite (Mg2SiO4) to fayalite (Fe2SiO4). Investigating the role of Fe(II) in olivine reactivity requires the ability to synthesize olivines that are nanometer-sized, have different percentages of Mg2+ and Fe2+, and have good bulk and surface purity. This article demonstrates a new method for synthesizing nanosized fayalite and Mg-Fe mixture olivines. First, carbonaceous precursors are generated from sucrose, PVA, colloidal silica, Mg2+, and Fe3+. Second, these precursors are calcined in air to burn carbon and create mixtures of Fe(III)-oxides, forsterite, and SiO2. Finally, calcination in reducing CO-CO2 gas buffer leads to Fe(II)-rich olivines. XRD, Mössbauer, and IR analyses verify good bulk purity and composition. XPS indicates that surface iron is in its reduced Fe(II) form, and surface Si is consistent with olivine. SEM shows particle sizes predominately between 50 and 450 nm, and BET surface areas are 2.8-4.2 m2/g. STEM HAADF analysis demonstrates even distributions of Mg and Fe among the available M1 and M2 sites of the olivine crystals. These nanosized Fe(II)-rich olivines are suitable for laboratory studies with in situ probes that require mineral samples with high reactivity at short timescales.

Formation, stability and structural characterization of ternary MgUO{sub 2}(CO{sub 3}){sub 3}{sup 2-} and Mg{sub 2}UO{sub 2}(CO{sub 3}){sub 3}(aq) complexes

Energy Technology Data Exchange (ETDEWEB)

Lee, Jun-Yeop; Yun, Jong-Il [KAIST, Daejeon (Korea, Republic of). Dept. of Nuclear and Quantum Engineering; Vespa, Marika; Gaona, Xavier; Dardenne, Kathy; Rothe, Joerg; Rabung, Thomas; Altmaier, Marcus [Karlsruhe Institute of Technology, Karlsruhe (Germany). Inst. for Nuclear Waste Disposal

2017-06-01

The formation of ternary Mg-UO{sub 2}-CO{sub 3} complexes under weakly alkaline pH conditions was investigated by time-resolved laser fluorescence spectroscopy (TRLFS) and extended X-ray absorption fine structure (EXAFS) and compared to Ca-UO{sub 2}-CO{sub 3} complexes. The presence of two different Mg-UO{sub 2}-C{sub 3} complexes was identified by means of two distinct fluorescence lifetimes of 17±2 ns and 51±2 ns derived from the multi-exponential decay of the fluorescence signal. Slope analysis in terms of fluorescence intensity coupled with fluorescence intensity factor as a function of log [Mg(II)] was conducted for the identification of the Mg-UO{sub 2}-CO{sub 3} complexes forming. For the first time, the formation of both MgUO{sub 2}(CO{sub 3}){sub 3}{sup 2-} and Mg{sub 2}UO{sub 2}(CO{sub 3}){sub 3}(aq) species was confirmed and the corresponding equilibrium constants were determined as log β {sub 113}=25.8±0.3 and β {sub 213}=27.1±0.6, respectively. Complementarily, fundamental structural information for both Ca-UO{sub 2}-CO{sub 3} and Mg-UO{sub 2}-CO{sub 3} complexes was gained by extended EXAFS revealing very similar structures between these two species, except for the clearly shorter U-Mg distance (3.83 Aa) compared with U-Ca distance (4.15 Aa). These results confirmed the inner-sphere character of the Ca/Mg-UO{sub 2}-CO{sub 3} complexes. The formation constants determined for MgUO{sub 2}(CO{sub 3}){sub 3}{sup 2-} and Mg{sub 2}UO{sub 2}(CO{sub 3}){sub 3}(aq) species indicate that ternary Mg-UO{sub 2}-CO{sub 3} complexes contribute to the relevant uranium species in carbonate saturated solutions under neutral to weakly alkaline pH conditions in the presence of Mg(II) ions, which will induce notable influences on the U(VI) chemical species under seawater conditions.

Enabling rechargeable non-aqueous Mg-O2 battery operations with dual redox mediators.

Science.gov (United States)

Dong, Qi; Yao, Xiahui; Luo, Jingru; Zhang, Xizi; Hwang, Hajin; Wang, Dunwei

2016-12-11

Dual redox mediators (RMs) were introduced for Mg-O 2 batteries. 1,4-Benzoquinone (BQ) facilitates the discharge with an overpotential reduction of 0.3 V. 5,10,15,20-Tetraphenyl-21H,23H-porphine cobalt(ii) (Co(ii)TPP) facilitates the recharge with an overpotential decrease of up to 0.3 V. Importantly, the two redox mediators are compatible in the same DMSO-based electrolyte.

Separation and recovery of lead from a low concentration solution of lead(II) and zinc(II) using the hydrolysis production of poly styrene-co-maleic anhydride

Energy Technology Data Exchange (ETDEWEB)

Liang, Xing; Su, Yibing [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou (China); Yang, Ying, E-mail: Yangying@lzu.edu.cn [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou (China); Qin, Wenwu [College of Chemistry and Chemical Engineering, Lanzhou University, Lanzhou (China)

2012-02-15

Highlights: Black-Right-Pointing-Pointer Separation and recovery of Pb(II) from a solution of Pb(II) and Zn(II) was performed. Black-Right-Pointing-Pointer Pb(II) can be recovered using the hydrolysis production of poly styrene-co-maleic anhydride. Black-Right-Pointing-Pointer The adsorption capacity of the PSMA resin for Pb(II) is 641.62 mg g{sup -1}. Black-Right-Pointing-Pointer Pb(II) can be recovered through desorption of Pb-PSMA into Pb(II) ion and the solid PSMA resin. Black-Right-Pointing-Pointer The resin can be repeatedly used through desorption by an inorganic acid condition (6 M H{sub 2}SO{sub 4}). - Abstract: The Pb-Zn separation/preconcentration technique, based on the complex formation reaction of Pb(II) and Zn(II), using a copolymer poly(styrene-co-maleic anhydride) (PSMA), without adding any carrier element was developed. The effects of several experimental parameters such as solution pH, temperature and adsorption time were studied. The experimental results show that the PSMA resin-Pb equilibrium was achieved in 2 min and the Pb(II) loading capacity is up to 641.62 mg g{sup -1} in aqueous solution under optimum conditions, which is much higher than the Zn(II) loading capacity within 80 min. The adsorption test for Pb(II) indicates that PSMA can recover Pb(II) from a mixed solution of Pb(II), Zn(II) and light metals such as Ca(II) and Mg(II) with higher adsorption rate and larger selective coefficient. A further study indicates that PSMA as chelating resins recovering Pb(II) can be regenerated via mineral acid (6 M H{sub 2}SO{sub 4}). PSMA was synthesized by radical polymerization and tested as an adsorbent for the selective recovery of Pb(II). In addition, the formation procedure and structure of Pb-PSMA complex were also studied. Both the PSMA and the Pb-PSMA complex were characterized by means of FTIR spectroscopy, elemental analysis, gel permeation chromatography (GPC) and atomic absorption spectrometry (AAS).

Equilibrium modeling of mono and binary sorption of Cu(II and Zn(II onto chitosan gel beads

Directory of Open Access Journals (Sweden)

Nastaj Józef

2016-12-01

Full Text Available The objective of the work are in-depth experimental studies of Cu(II and Zn(II ion removal on chitosan gel beads from both one- and two-component water solutions at the temperature of 303 K. The optimal process conditions such as: pH value, dose of sorbent and contact time were determined. Based on the optimal process conditions, equilibrium and kinetic studies were carried out. The maximum sorption capacities equaled: 191.25 mg/g and 142.88 mg/g for Cu(II and Zn(II ions respectively, when the sorbent dose was 10 g/L and the pH of a solution was 5.0 for both heavy metal ions. One-component sorption equilibrium data were successfully presented for six of the most useful three-parameter equilibrium models: Langmuir-Freundlich, Redlich-Peterson, Sips, Koble-Corrigan, Hill and Toth. Extended forms of Langmuir-Freundlich, Koble-Corrigan and Sips models were also well fitted to the two-component equilibrium data obtained for different ratios of concentrations of Cu(II and Zn(II ions (1:1, 1:2, 2:1. Experimental sorption data were described by two kinetic models of the pseudo-first and pseudo-second order. Furthermore, an attempt to explain the mechanisms of the divalent metal ion sorption process on chitosan gel beads was undertaken.

Adsorption of manganese(II) ions by EDTA-treated activated carbons

Energy Technology Data Exchange (ETDEWEB)

Khan, A.Y.; Mazyck, D.W. [Jones Edmunds & Associates, Gainesville, FL (United States)

2009-07-01

The adsorption of manganese(II) ions from aqueous solution onto three different granular activated carbons treated with ethylenediamine tetraacetic acid (EDTA) and its sodium salt was investigated. Characterization of the chelate-treated carbons showed that EDTA altered the physical and chemical properties of the sorbents relative to their untreated counterparts. Furthermore, the modified sorbents exhibited a heightened capacity towards the adsorption of Mn(II) ions from aqueous media. Manganese(II) ion removal increased from 0 to 6.5 mg/g for the lignite coal-based sorbent, from 3.5 to 14.7 mg/g for the wood-based sorbent and from 1.3 to 7.9 mg/g for the bituminous coal-based sorbent. The increased removal is attributed, in part, to the creation of Lewis base sites that participate in covalent interactions and hydrolysis reactions.

FLARE-LIKE VARIABILITY OF THE Mg II {lambda}2800 EMISSION LINE IN THE {gamma}-RAY BLAZAR 3C 454.3

Energy Technology Data Exchange (ETDEWEB)

Leon-Tavares, J. [Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Vaeisaelaentie 20, FI-21500 Piikkioe (Finland); Chavushyan, V.; Patino-Alvarez, V.; Carraminana, A.; Carrasco, L. [Instituto Nacional de Astrofisica Optica y Electronica (INAOE), Apartado Postal 51 y 216, 72000 Puebla (Mexico); Valtaoja, E. [Tuorla Observatory, Department of Physics and Astronomy, University of Turku, FI-20100 Turku (Finland); Arshakian, T. G. [I. Physikalisches Institut, Universitaet zu Koeln, Zuelpicher Str. 77, D-50937 Koeln (Germany); Popovic, L. C. [Astronomical Observatory, Volgina 7, 11160 Belgrade 74 (Serbia); Tornikoski, M.; Laehteenmaeki, A. [Aalto University Metsaehovi Radio Observatory, Metsaehovintie 114, FI-02540 Kylmaelae (Finland); Lobanov, A. [Max-Planck-Institut fuer Radioastronomie, Auf dem Huegel 69, D-53121 Bonn (Germany)

2013-02-01

We report the detection of a statistically significant flare-like event in the Mg II {lambda}2800 emission line of 3C 454.3 during the outburst of autumn 2010. The highest levels of emission line flux recorded over the monitoring period (2008-2011) coincide with a superluminal jet component traversing through the radio core. This finding crucially links the broad emission line fluctuations to the non-thermal continuum emission produced by relativistically moving material in the jet and hence to the presence of broad-line region clouds surrounding the radio core. If the radio core were located at several parsecs from the central black hole, then our results would suggest the presence of broad-line region material outside the inner parsec where the canonical broad-line region is envisaged to be located. We briefly discuss the implications of broad emission line material ionized by non-thermal continuum in the context of virial black hole mass estimates and gamma-ray production mechanisms.

Transfer and control of molecular chirality in the 1 : 2 host-guest supramolecular complex consisting of Mg(II)bisporphyrin and chiral diols: the effect of H-bonding on the rationalization of chirality.

Science.gov (United States)

Ikbal, Sk Asif; Brahma, Sanfaori; Rath, Sankar Prasad

2014-11-21

A clear rationalization of the origin of chirality transfer from an optically active diol guest to an achiral Mg(ii)bisporphyrin host in a series of 1 : 2 host-guest supramolecular complexes has been reported here that has so far remained the most outstanding issue for the chirogenic process.

Seaweeds for the remediation of wastewaters contaminated with zinc(II) ions

International Nuclear Information System (INIS)

Senthilkumar, R.; Vijayaraghavan, K.; Thilakavathi, M.; Iyer, P.V.R.; Velan, M.

2006-01-01

Eleven different species of marine macroalgae were screened at different pH conditions on the basis of zinc(II) biosorption potential. Among the seaweeds, a green alga, Ulva reticulata, exhibited a highest uptake of 36.1 mg/g at pH 5.5 and 100 mg/l initial zinc(II) concentration. Further experiments were conducted to evaluate the zinc(II) biosorption potential of U. reticulata. Sorption isotherm data obtained at different pH (5-6) and temperature (25-35 deg. C) conditions were fitted well with Sips model followed by Freundlich, Redlich-Peterson and Langmuir models. A maximum zinc(II) biosorption capacity of 135.5 mg/g was observed at optimum conditions of 5.5 (pH) and 30 deg. C (temperature), according to the Langmuir model. It was observed from the kinetic data that the zinc(II) biosorption process using U. reticulata follows pseudo-second-order kinetics. Various thermodynamic parameters, such as ΔG o , ΔH o and ΔS o were calculated and they indicated that the present system was a spontaneous and an endothermic process. The influence of the co-ions (Na + , K + , Ca 2+ and Mg 2+ ) along with zinc(II) present in the wastewater was also studied. Desorption of zinc(II) ions from the zinc(II)-loaded biomass were examined using 0.1 M CaCl 2 at different pH conditions in three sorption-desorption cycles. A fixed-bed column (2 cm i.d. and 35 cm height) was employed to evaluate the continuous biosorption performance of U. reticulata. The column experiments at different bed heights and flow rates revealed that the maximum zinc(II) uptake was obtained at the highest bed height (25 cm) and the lowest flow rate (5 ml/min). Column data were fitted well with Thomas, Yoon-Nelson and modified dose-response models. The column regeneration studies were carried out for three sorption-desorption cycles. A loss of sorption performance was observed during regeneration cycles indicated by a shortened breakthrough time and a decreased zinc(II) uptake

Application of bifunctional Saccharomyces cerevisiae to remove lead(II) and cadmium(II) in aqueous solution

International Nuclear Information System (INIS)

Zhang Yunsong; Liu Weiguo; Zhang Li; Wang Meng; Zhao Maojun

2011-01-01

A magnetic adsorbent, EDTAD-functionalized Saccharomyces cerevisiae, has been synthesized to behave as an adsorbent for heavy metal ions by adjusting the pH value of the aqueous solution to make carboxyl and amino groups protonic or non-protonic. The bifunctional Saccharomyces cerevisiae (EMS) were used to remove lead(II) and cadmium(II) in solution in a batch system. The results showed that the adsorption capacity of the EMS for the heavy metal ions increased with increasing solution pH, and the maximum adsorption capacity (88.16 mg/g for Pb 2+ , 40.72 mg/g for Cd 2+ ) at 10 deg. C was found to occur at pH 5.5 and 6.0, respectively. The adsorption process followed the Langmuir isotherm model. The regeneration experiments revealed that the EMS could be successfully reused.

Toxicity assessment of Chlorella vulgaris and Chlorella protothecoides following exposure to Pb(II).

Science.gov (United States)

Zhang, Wei; Xiong, Bang; Chen, Lin; Lin, Kuangfei; Cui, Xinhong; Bi, Huasong; Guo, Meijin; Wang, Weiliang

2013-07-01

The short- and long-term toxic effects of Pb(II) exposure on Chlorella vulgaris (C. vulgaris) and Chlorella protothecoides (C. protothecoides) were not well understood. The lab study was performed to observe the Pb(II) exposure induced changes. Results of the observations show: (1) higher level of Pb(II) (50 or 80mgL(-1)) could significantly inhibit the growth and chlorophyll a synthesis of both algae in almost all the treatments and dose-response relationships could be clearly observed, (2) the range of EC50 values (24-120h, 67.73-172.45mgL(-1)) indicated that Pb(II) had a relatively limited short-term toxicity to the two algae, while long-term tests (7-28d, 50.41-63.91mgL(-1)) displayed higher toxicity and (3) SOD and CAT activities of both algae after exposed to medium level of Pb(II) were significantly promoted, and their response might be more susceptible in short-term exposure. This research provides a basic understanding of Pb(II) toxicity to aquatic organisms. Copyright © 2013 Elsevier B.V. All rights reserved.

How relevant is heterogeneous chemistry on Mars? Strong tests via global mapping of water and ozone (sampled via O2 dayglow)

Science.gov (United States)

Villanueva, Geronimo Luis; Mumma, Michael J.; Novak, Robert E.

2015-11-01

Ozone and water are powerful tracers of photochemical processes on Mars. Considering that water is a condensable with a multifaceted hydrological cycle and ozone is continuously being produced / destroyed on short-time scales, their maps can test the validity of current 3D photochemical and dynamical models. Comparisons of modern GCM models (e.g., Lefèvre et al. 2004) with certain datasets (e.g., Clancy et al. 2012; Bertaux et al. 2012) point to significant disagreement, which in some cases have been related to heterogeneous (gas-dust) chemistry beyond the classical gas-gas homogeneous reactions.We address these concerns by acquiring full 2D maps of water and ozone (via O2 dayglow) on Mars, employing high spectral infrared spectrometers at ground-based telescopes (CRIRES/VLT and CSHELL/NASA-IRTF). By performing a rotational analysis on the O2 lines, we derive molecular temperature maps that we use to derive the vertical level of the emission (e.g., Novak et al. 2002). Our maps sample the full observable disk of Mars on March/25/2008 (Ls=50°, northern winter) and on Jan/29/2014 (Ls=83°, northern spring). The maps reveal a strong dependence of the O2 emission and water burden on local orography, while the temperature maps are in strong disagreement with current models. Could this be the signature of heterogeneous chemistry? We will present the global maps and will discuss possible scenarios to explain the observations.This work was partially funded by grants from NASA's Planetary Astronomy Program (344-32-51-96), NASA’s Mars Fundamental Research Program (203959.02.02.20.29), NASA’s Astrobiology Program (344-53-51), and the NSF-RUI Program (AST-805540). We thank the administration and staff of the European Southern Observatory/VLT and NASA-IRTF for awarding observing time and coordinating our observations.Bertaux, J.-L., Gondet, B., Lefèvre, F., et al. 2012. J. Geophys. Res. Pl. 117. pp. 1-9.Clancy, R.T., Sandor, B.J., Wolff, M.J., et al. 2012. J. Geophys. Res

Perbandingan Gabapentin 600 mg dengan 1.200 mg per Oral Preoperatif terhadap Nilai Visual Analogue Scale dan Pengurangan Kebutuhan Petidin Pascaoperasi pada Modifikasi Mastektomi Radikal

Directory of Open Access Journals (Sweden)

Ardi Zulfariansyah

2013-12-01

Full Text Available Gabapentin is a GABA analog which has the effect of anti hyperalgesia, anti allodynia, and anti nociceptive. This research was conducted in order to assess the effect of 600mg and 1,200 mg gabapentin given preoperatively to assess visual analogue scale (VAS score and reduction of pethidine requirement. The study was done by conducting a double blind randomized controlled trial on 38 patients, aged 18–65 years, with ASA physical status I–II. Patients were divided into two groups: 600 mg gabapentin and 1,200 mg gabapentin group. The quality of pain was assessed using VAS score. The results were statistically analyzed using Mann-Whitney Test with 95% confidence interval and considered significant if p value <0.05. From the results, the VAS values obtained at rest and during mobilization were significantly different (p<0.05. The 1,200 mg gabapentin group received less additional pethidine (10.5% vs 15.8%, although no significant difference was shown (p=0.631. The conclusion of this study is that administration of 1,200 mg gabapentin per oral pre operatively is better when compared to 600 mg in reducing post operative visual analog scale score in modified radical mastectomy. However, it do not reduce the need for analgesic significantly.

Anticonvulsant activity of DNS II fraction in the acute seizure models.

Science.gov (United States)

Raza, Muhammad Liaquat; Zeeshan, Mohammad; Ahmad, Manzoor; Shaheen, Farzana; Simjee, Shabana U

2010-04-21

Delphinium nordhagenii belongs to family Ranunculaceae, it is widely found in tropical areas of Pakistan. Other species of Delphinium are reported as anticonvulsant and are traditionally used in the treatment of epilepsy. Delphinium nordhagenii is used by local healer in Pakistan but never used for scientific investigation as anticonvulsant. Thus, Delphinium nordhagenii was subjected to bioassay-guided fractionation and the most active fraction, i.e. DNS II acetone was chosen for further testing in the acute seizure models of epilepsy to study the antiepileptic potential in male mice. Different doses (60, 65 and 70mg/kg, i.p.) of DNS II acetone fraction of Delphinium nordhagenii was administered 30min prior the chemoconvulsant's injection in the male mice. Convulsive doses of chemoconvulsants (pentylenetetrazole 90mg/kg, s.c. and picrotoxin 3.15mg/kg, s.c.) were used. The mice were observed 45-90min for the presence of seizures. Moreover, four different doses of DNS II (60, 65, 70 and 100mg/kg, i.p.) were tested in the MES test. The DNS II acetone fraction of Delphinium nordhagenii has exhibited the anticonvulsant actions by preventing the seizures against PTZ- and picrotoxin-induced seizure as well as 100% seizure protection in MES test. The results are comparable with standard AEDs (diazepam 7.5mg/kg, i.p. and phenytoin 20mg/kg, i.p.). These findings suggest that the Delphinium nordhagenii possesses the anticonvulsant activity. Further analysis is needed to confirm the structure and target the extended activity profile. Copyright 2010 Elsevier Ireland Ltd. All rights reserved.

Angiotensin II inhibits cortical cholinergic function: Implications for cognition

International Nuclear Information System (INIS)

Barnes, J.M.; Barnes, N.M.; Costall, B.; Horovitz, Z.P.; Ironside, J.W.; Naylor, R.J.; Williams, T.J.

1990-01-01

In the present studies we have shown that angiotensin II (AT II), in a concentration-dependent manner in rat tissue (10(-9)-10(-5) M) or at a single concentration in human tissue (10(-6) M), can inhibit potassium-stimulated release of [3H]acetylcholine ( [3H]Ach) from slices of rat entorhinal cortex and human temporal cortex preloaded with [3H]choline for the biochemical analyses. The inhibitory effects of AT II (10(-6) M) were antagonised by the specific AT II receptor antagonist [1-sarcosine, 8-threonine]AT II in a concentration-dependent manner in rat tissue (10(-11)-10(-8) M) and at the single concentration employed in the human studies (10(-7) M). Also demonstrated were other components of the angiotensin system in the human temporal cortex; ACE activity was present (1.03 nmol min-1 mg-1 protein), as were AT II recognition sites (Bmax = 8.6 fmol mg-1 protein). It is hypothesised that the potential cognitive enhancing properties of ACE inhibitors may reflect their action to prevent the formation of AT II and so remove an inhibitory modulator of cholinergic function

Effects of waterborne Fe(II) on juvenile turbot Scophthalmus maximus: analysis of respiratory rate, hematology and gill histology

Science.gov (United States)

Wu, Zhihao; You, Feng; Liu, Hongjun; Liu, Mengxia; Li, Jun; Zhang, Peijun

2012-03-01

The concentration of Fe(II) is high in some groundwater supplies used in turbot culture, and the toxicity of waterborne Fe(II) is unknown. We investigated the stress responses of juvenile turbot, Scophthalmus maximus, exposed to Fe(II) of different concentrations (0.01, 0.05, 0.1, 0.5, 1, and 2 mg/L) for 1, 7, 14, and 28 d, under the same ambient conditions of other parameters. Changes in respiratory rate, hematological parameters, and gill structure were determined. The results show that waterborne Fe(II) did not cause severe hematological perturbation to turbot. A low-medium Fe(II) concentration (lower than 0.1 mg/L) could boost the respiratory rate, and caused no or very limited damage to fish. A high Fe(II) concentration (0.1 mg/L or higher), however, caused gill damage, such as vacuoles in branchial lamellae, epithelial necrosis, and hypertrophy of epithelial cells, and even death after extended exposure time. Therefore, excess waterborne Fe(II) and long-term exposure to Fe(II) could be responsible for poor growth and high mortality of turbot in culture. The concentration of waterborne Fe(II) in turbot culture should be kept below 0.1 mg/L.

Enhanced mechanical properties of an Al–Si–Cu–Mg alloy at 300 °C: Effects of Mg and the Q-precipitate phase

Energy Technology Data Exchange (ETDEWEB)

Farkoosh, A.R., E-mail: amir.rezaeifarkoosh@mail.mcgill.ca; Pekguleryuz, M., E-mail: mihriban.pekguleryuz@mcgill.ca

2015-01-05

Strategies to improve the strength of Al–Si alloys at elevated temperatures can follow two routes: (i) improving the age-hardening behavior and/or (ii) producing effective dispersoid strengthening. In this study, the influence of Mg (in the range of 0.3–0.7 wt%) on the precipitation characteristics and mechanical properties of the Al–7Si–0.5Cu–(Mg) alloy was investigated. Thermodynamic calculations were performed via the CALPHAD method which showed that Q-Al{sub 5}Mg{sub 8}Cu{sub 2}Si{sub 6} is the main thermodynamically stable precipitate at 300 °C. The calculations were validated by transmission electron microscopy and differential scanning calorimetry analyses. Increasing the Mg level from 0.3 wt% to the maximum solubility limit of ∼0.5 wt% increased the amount of the Q-Al{sub 5}Mg{sub 8}Cu{sub 2}Si{sub 6} precipitates at 300 °C by ∼60 wt% and significantly improved the tensile strength and creep resistance at the expense of some ductility. Mg in excess of the solubility limit was seen to remain within the microstructure in the form of the large π-Al{sub 8}FeMg{sub 3}Si{sub 6} and β-Mg{sub 2}Si intermetallics after solution treatment at 530 °C. Cracking of the brittle π-Al{sub 8}FeMg{sub 3}Si{sub 6} intermetallics during deformation was accounted for the decreased ductility of the alloys at high Mg levels. It is concluded that the Mg level can be increased to 0.5 wt% in the A–7Si–0.5Cu alloys to improve strength. However, for elevated temperature applications in which both strength and ductility are required (e.g. Diesel engine), modification of the π-Al{sub 8}FeMg{sub 3}Si{sub 6} intermetallics would be required to improve the ductility of the alloys with high Mg contents.

Efficient removal of cobalt(II) and strontium(II) metals from water using ethylene diamine tetra-acetic acid functionalized graphene oxide

Energy Technology Data Exchange (ETDEWEB)

Amer, Hany; Moustafa, Wafaa M. [Nuclar Fuel Cycle Department, Nuclear and Radiological Regulatory Authority (NRRA), Naser City, Cairo (Egypt); Farghali, Ahmed A.; El Rouby, Waleed M.A. [Materials Science and Nanotechnology Department, Faculty of Postgraduate Studies for Advanced Sciences (PASA), Beni-Suef University (Egypt); Khalil, Waleed F. [Nuclar Fuel Cycle Department, Nuclear and Radiological Regulatory Authority (NRRA), Naser City, Cairo (Egypt); Materials Science and Nanotechnology Department, Faculty of Postgraduate Studies for Advanced Sciences (PASA), Beni-Suef University (Egypt)

2017-12-04

Graphene oxide (GO) with high specific surface area was prepared and functionalized with ethylene diamine tetra-acetic acid (EDTA). The as-prepared GO and the functionalized one (GO-EDTA) were characterized using high resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and Raman spectroscopy. The as-prepared and EDTA functionalized GO were applied as adsorbent to remove strontium(II) and cobalt(II) from water. The results indicated that the prepared materials are efficient adsorbents for strontium(II) and cobalt(II) removal. The adsorption of Co{sup II} and Sr{sup II} under effects of contact time, temperature, and pH was investigated It is concluded that the maximum adsorption capacities of GO for Co{sup II} and Sr{sup II} were about 168 and 140 mg.g{sup -1}, whereas of GO-EDTA the values were about 197 and 158 mg.g{sup -1}, respectively. It is indicated that pH 6 and temperature 40 C are the best condition for Co{sup II} and Sr{sup II} removal from water. The application of Langmuir and Freundlich isotherms indicated that Langmuir isotherm is best fit for Co{sup II} and Sr{sup II} equilibrium adsorption. Adsorption kinetics were studied by applying pseudo first-order, pseudo second-order, and intraparticle diffusion models on the experimental data. The results proved that pseudo second-order model is the best represented adsorption kinetics. Appling the intraparticle diffusion regressions on the experimental data indicated that intraparticle diffusion involved in adsorption process, which was not the only rate-controlling step. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Decontamination of Hg(II) from aqueous solution using polyamine-co-thiourea inarched chitosan gel derivatives.

Science.gov (United States)

Liang, Wen; Li, Manlin; Zhang, Zengqiang; Jiang, Yahui; Awasthi, Mukesh Kumar; Jiang, Shuncheng; Li, Ronghua

2018-07-01

Ethylenediamine (EDA), triethylenetetramine (TETA) and tetraethylenepentamine (TEPA) had been successfully introduced into the structure of thiourea (TC) modified chitosan (CS) by using formaldehyde as linkage, respectively. The resulted materials, TC-CS, TC-EDA-CS, TC-TETA-CS, and TC-TEPA-CS were characterized and employed as adsorbents in batch experiment for the Hg(II) removal. We have found the modification enhanced the Hg(II) adsorption significantly in comparison with raw CS. Hg(II) adsorption amounts for all adsorbents increased gradually and reached maxima at pH≥4.0. The adsorption of Hg(II) achieved an equilibrium state within 12h with the process drove by the pseudo-second-order model. The ionic strength had no remarkable inhibition effect on Hg(II) adsorption. While the Hg(II) adsorption capacities of the adsorbents were strongly related with the modifier types and the length of the incorporating amino ligands. Langmuir model described Hg(II) adsorption well with the maximum adsorption capacities of prepared adsorbents in order of TC-EDA-CS (217.1mg/g)>TC-CS (164.8mg/g)>TC-TETA-CS (149.7mg/g)>TC-TEPA-CS (140.6mg/g) at room temperature. The FT-IR and XPS investigations implied that Hg(II) ion adsorption mechanism was characterized by a complexation reaction process. Adsorbents could be readily regenerated and had great reusability potential in Hg(II) ions capture from aqueous solution. Copyright © 2018 Elsevier B.V. All rights reserved.

Pseudopotential approach to superconductivity in MgB2

International Nuclear Information System (INIS)

Sharma, K.S.; Bhargava, Nidhi; Jain, Ritu; Goyal, Varsha; Sharma, Ritu; Sharma, Smita

2010-01-01

Superconductivity in MgB 2 has been re-examined in BCS-Eliashberg framework by employing Mc-Millan's T c -equation and form factors of MgB 2 computed from the form factors of component metals (Model-I). The empty core model pseudopotential due to Ashcroft and random phase approximation form of dielectric screening due to Gellmann and Brueckner are used in the present work. An excellent agreement between the present values and other theoretically computed values of T c and with the relevant experimental data for MgB 2 confirms the validity of the present approach. The explicit dependence of λ and T c on the isotopic masses of Mg and B, as revealed from the present work, confirms the role of lattice vibrations in the superconducting behaviour of MgB 2 and the high value of T c in it may be attributed to the phonon mediated e-e interaction coupled with higher values of phonon frequencies due to light mass of B atoms. It has also been observed that the pseudo-atom model (Model-II) with appropriate choice of the potential parameter r c successfully explains high value of T c and isotope effect in MgB 2 , confirming the prominent role played by electron-phonon interaction in the high-T c superconductivity observed in MgB 2 . The isotope effect exponent α-values obtained from the two models are in complete agreement with each other and the present value α = 0.46 is also much closer to the BCS value of 0.5. Interaction strength N 0 V values obtained from the two models are also in perfect agreement with each other and the present value N 0 V = 0.48 suggests that MgB 2 is a strong coupling superconductor. (author)

Application of bifunctional Saccharomyces cerevisiae to remove lead(II) and cadmium(II) in aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Zhang Yunsong [Department of Chemistry, College of Life and Science, Sichuan Agricultural University, Yaan 625014 (China); Liu Weiguo [Agronomy College, Sichuan Agricultural University, Wenjiang 611130 (China); Zhang Li; Wang Meng [Department of Chemistry, College of Life and Science, Sichuan Agricultural University, Yaan 625014 (China); Zhao Maojun, E-mail: yaanyunsong@yahoo.com.cn [Department of Chemistry, College of Life and Science, Sichuan Agricultural University, Yaan 625014 (China)

2011-09-15

A magnetic adsorbent, EDTAD-functionalized Saccharomyces cerevisiae, has been synthesized to behave as an adsorbent for heavy metal ions by adjusting the pH value of the aqueous solution to make carboxyl and amino groups protonic or non-protonic. The bifunctional Saccharomyces cerevisiae (EMS) were used to remove lead(II) and cadmium(II) in solution in a batch system. The results showed that the adsorption capacity of the EMS for the heavy metal ions increased with increasing solution pH, and the maximum adsorption capacity (88.16 mg/g for Pb{sup 2+}, 40.72 mg/g for Cd{sup 2+}) at 10 deg. C was found to occur at pH 5.5 and 6.0, respectively. The adsorption process followed the Langmuir isotherm model. The regeneration experiments revealed that the EMS could be successfully reused.

Effects of lead(II) on the extracellular polysaccharide (EPS) production and colony formation of cultured Microcystis aeruginosa.

Science.gov (United States)

Bi, Xiang-dong; Zhang, Shu-lin; Dai, Wei; Xing, Ke-zhing; Yang, Fan

2013-01-01

To investigate the effects of lead(II) on the production of extracellular polysaccharides (EPS), including bound extracellular polysaccharides (bEPS) and soluble extracellular polysaccharides (sEPS), and the colony formation of Microcystis aeruginosa, cultures of M. aeruginosa were exposed to four concentrations (5.0, 10.0, 20.0 and 40.0 mg/L) of lead(II) for 10 d under controlled laboratory conditions. The results showed that 5.0 and 10.0 mg/L lead(II) stimulated M. aeruginosa growth throughout the experiment while 20.0 and 40.0 mg/L lead(II) inhibited M. aeruginosa growth in the first 2 d exposure and then stimulated it. As compared to the control group, significant increases in the bEPS and sEPS production were observed in 20.0 and 40.0 mg/L lead(II) treatments (P bEPS production, which conversely promoted colony formation, suggesting that heavy metals might be contributing to the bloom-forming of M. aeruginosa in natural conditions.

Nitrogen vacancies as a common element of the green luminescence and nonradiative recombination centers in Mg-implanted GaN layers formed on a GaN substrate

Science.gov (United States)

Kojima, Kazunobu; Takashima, Shinya; Edo, Masaharu; Ueno, Katsunori; Shimizu, Mitsuaki; Takahashi, Tokio; Ishibashi, Shoji; Uedono, Akira; Chichibu, Shigefusa F.

2017-06-01

The photoluminescences of ion-implanted (I/I) and epitaxial Mg-doped GaN (GaN:Mg) are compared. The intensities and lifetimes of the near-band-edge and ultraviolet luminescences associated with a MgGa acceptor of I/I GaN:Mg were significantly lower and shorter than those of the epilayers, respectively. Simultaneously, the green luminescence (GL) became dominant. These emissions were quenched far below room temperature. The results indicate the generation of point defects common to GL and nonradiative recombination centers (NRCs) by I/I. Taking the results of positron annihilation measurement into account, N vacancies are the prime candidate to emit GL and create NRCs with Ga vacancies, (VGa) m (VN) n , as well as to inhibit p-type conductivity.

High mobility 2D electron gas in CdTe/CdMgTe heterostructures

International Nuclear Information System (INIS)

Karczewski, G.; Jaroszynski, J.; Kurowski, M.; Barcz, A.; Wojtowicz, T.; Kossut, J.

1997-01-01

We report on iodine doping of molecular beam epitaxy (MBE)-grown Cd(Mn)Te quasi-bulk films and modulation-doped CdTe/Cd 1-y Mg y Te two-dimensional (2D) single quantum well structures. Modulation doping with iodine of CdTe/Cd 1-y Mg y Te structures resulted in fabrication of a 2D electron gas with mobility exceeding 10 5 cm 2 /(Vs). This is the highest mobility reported in wide-gap II-VI materials

Separation and recovery of lead from a low concentration solution of lead(II) and zinc(II) using the hydrolysis production of poly styrene-co-maleic anhydride.

Science.gov (United States)

Liang, Xing; Su, Yibing; Yang, Ying; Qin, Wenwu

2012-02-15

The PbZn separation/preconcentration technique, based on the complex formation reaction of Pb(II) and Zn(II), using a copolymer poly(styrene-co-maleic anhydride) (PSMA), without adding any carrier element was developed. The effects of several experimental parameters such as solution pH, temperature and adsorption time were studied. The experimental results show that the PSMA resin-Pb equilibrium was achieved in 2 min and the Pb(II) loading capacity is up to 641.62 mg g(-1) in aqueous solution under optimum conditions, which is much higher than the Zn(II) loading capacity within 80 min. The adsorption test for Pb(II) indicates that PSMA can recover Pb(II) from a mixed solution of Pb(II), Zn(II) and light metals such as Ca(II) and Mg(II) with higher adsorption rate and larger selective coefficient. A further study indicates that PSMA as chelating resins recovering Pb(II) can be regenerated via mineral acid (6M H(2)SO(4)). PSMA was synthesized by radical polymerization and tested as an adsorbent for the selective recovery of Pb(II). In addition, the formation procedure and structure of Pb-PSMA complex were also studied. Both the PSMA and the Pb-PSMA complex were characterized by means of FTIR spectroscopy, elemental analysis, gel permeation chromatography (GPC) and atomic absorption spectrometry (AAS). Copyright © 2011 Elsevier B.V. All rights reserved.

Differential electron scattering cross sections for the 3 (2)S to 3 (2)P0 h, k transitions in Mg II - Comparison of experiment and theory

Science.gov (United States)

Williams, I. D.; Chutjian, A.; Msezane, A. Z.; Henry, R. J. W.

1985-01-01

Angular differential electron scattering cross sections are reported for the unresolved inelastic 3s (2)S to 3p (2)P0 h, k transitions in Mg II for the first time. Relative differential cross sections have been measured at 35 eV and 50 eV in the angular range of Theta between 6 and 17 deg using the newly developed electron energy loss technique in a crossed electron-ion beam geometry. Theoretical values have been calculated in a five-state close-coupling approximation in which 3s, 3p, 3d, 4s, and 4p states were included, and to which measurements were normalized at Theta = 12 deg.

A metal-organic framework nanocomposite made from functionalized magnetite nanoparticles and HKUST-1 (MOF-199) for preconcentration of Cd(II), Pb(II), and Ni(II)

International Nuclear Information System (INIS)

Ghorbani-Kalhor, Ebrahim

2016-01-01

The author describes the preparation of a magnetic metal organic framework of type MOF-199 containing magnetite (Fe 3 O 4 ) nanoparticles carrying covalently immobilized 4-(thiazolylazo) resorcinol (Fe 3 O 4 -TAR). This material is shown to represent a viable sorbent for separation and preconcentration of Cd(II), Pb(II), and Ni(II) ions. Box-Behnken design was applied to optimize the parameters affecting preconcentration. Following elution with 0.6 mol L −1 EDTA, the ions were quantified by FAAS. The capacity of the sorbent ranged between 185 and 210 mg g −1 . The limits of detection are 0.15, 0.40, and 0.8 ng mL −1 for Cd(II), Ni(II), and Pb(II) ions, respectively. The relative standard deviations are <8.5 %. The method was successfully applied to the rapid extraction of trace amounts of these ions from sea food and agri food. (author)

Application of EDTA-functionalized bamboo activated carbon (BAC) for Pb(II) and Cu(II) removal from aqueous solutions

Science.gov (United States)

Lv, Dan; Liu, Yu; Zhou, Jiasheng; Yang, Kunlun; Lou, Zimo; Baig, Shams Ali; Xu, Xinhua

2018-01-01

In this study, a novel bamboo activated carbon (BAC) with ethylene diamine tetraacetic acid (EDTA) functionality was prepared by direct grafting in the presence of tetraethyl orthosilicate (TEOS) as a crosslinking agent. The BAC@SiO2-EDTA was characterized by SEM, TEM, TGA, FTIR, XPS and its adsorption property for removal of Pb(II) and Cu(II) under various experimental conditions was also investigated. The characterization results reflected that EDTA was successfully assembled on the surface of the BAC and average pore size increased from 4.10 to 4.83 nm as BAC grafted with EDTA. Adsorption data fitted very well in Langmuir isotherm model and pseudo-second-order kinetic model. As compared with the raw BAC, the maximum adsorption capacities of BAC@SiO2-EDTA for the Pb(II) and Cu(II) increased from 45.45 to 123.45 mg g-1 and from 6.85 to 42.19 mg g-1, since the existence of EDTA on modified BAC promoted the formation of chemical complex. The removal of heavy metal ions mainly depended on the complexation with EDTA and the electrostatic attractions with negatively charged surface of BAC@SiO2-EDTA. The adsorption of Pb(II)/Cu(II) on the BAC@SiO2-EDTA was pH dependent and pH 5-6 was considered an optimum. However, lower temperature favored the adsorption and the maximum adsorption was recorded at 20 °C. In addition, BAC@SiO2-EDTA had an excellent reusability with about 40% decline in the adsorption capacity for Pb(II) after fifth reuse. Insignificant influences of co-existing cations and natural organic matter (NOM) were found on the adsorption of Pb(II) and Cu(II). All the results demonstrate that BAC@SiO2-EDTA is a potential adsorbent for metal ions in wastewater.

Aqueous solvation of Mg(ii) and Ca(ii): A Born-Oppenheimer molecular dynamics study of microhydrated gas phase clusters

Science.gov (United States)

León-Pimentel, C. I.; Amaro-Estrada, J. I.; Hernández-Cobos, J.; Saint-Martin, H.; Ramírez-Solís, A.

2018-04-01

The hydration features of [Mg(H2O)n ] 2 + and [Ca(H2O)n ] 2 + clusters with n = 3-6, 8, 18, and 27 were studied by means of Born-Oppenheimer molecular dynamics simulations at the B3LYP/6-31+G** level of theory. For both ions, it is energetically more favorable to have all water molecules in the first hydration shell when n ≤ 6, but stable lower coordination average structures with one water molecule not directly interacting with the ion were found for Mg2+ at room temperature, showing signatures of proton transfer events for the smaller cation but not for the larger one. A more rigid octahedral-type structure for Mg2+ than for Ca2+ was observed in all simulations, with no exchange of water molecules to the second hydration shell. Significant thermal effects on the average structure of clusters were found: while static optimizations lead to compact, spherically symmetric hydration geometries, the effects introduced by finite-temperature dynamics yield more prolate configurations. The calculated vibrational spectra are in agreement with infrared spectroscopy results. Previous studies proposed an increase in the coordination number (CN) from six to eight water molecules for [Ca(H2O)n ] 2 + clusters when n ≥ 12; however, in agreement with recent measurements of binding energies, no transition to a larger CN was found when n > 8. Moreover, the excellent agreement found between the calculated extended X-ray absorption fine structure spectroscopy spectra for the larger cluster and the experimental data of the aqueous solution supports a CN of six for Ca2+.

An extreme Fe II emitter the narrow line quasar PHL 1092

CERN Document Server

Bergeron, J

1980-01-01

A search for Fe II emission in a sample of radio-quiet quasars has revealed the outstanding properties of PHL 1092. Intense Fe II lines dominate the entire spectrum, and the Fe II UV multiplets are nearly as strong as the optical ones. In contrast the extreme weakness of the Balmer and Mg II lines is striking. For the first time, Fe I lines are identified in an extra-galactic object. The lines are narrow, with a FWHM of 1300 km s/sup -1/. The presence of Fe II UV lines and Fe I lines from the ground state requires moderate column densities. However Fe/sup 0/ can exist only in a region completely shielded from the UV continuum. The weakness of Mg II and H beta relative to Fe II lines is best explained by their thermalization. The emitting region is of high electron density n/sub e/ approximately=10/sup 12/ cm/sup -3/, low temperature T approximately=10000K, and has an optical depth in the Fe II UV lines tau /sub UV/ approximately=10/sup 3/-10/sup 4/. It is speculated that for higher densities all the lines wou...

Structural properties and spatial ordering in multilayered ZnMgTe/ZnSe type-II quantum dot structures

International Nuclear Information System (INIS)

Manna, U.; Noyan, I. C.; Neumark, G. F.; Zhang, Q.; Moug, R.; Salakhutdinov, I. F.; Dunn, K. A.; Novak, S. W.; Tamargo, M. C.; Kuskovsky, I. L.

2012-01-01

We report the structural properties and spatial ordering of multilayer ZnMgTe quantum dots (QDs) embedded in ZnSe, where sub-monolayer quantities of Mg were introduced periodically during growth in order to reduce the valence band offset of ZnTe QDs. The periodicity, period dispersion, individual layer thickness, and the composition of the multilayer structures were determined by comparing the experimental high resolution x-ray diffraction (HRXRD) spectra to simulated ones for the allowed (004) and quasi-forbidden (002) reflections in combination with transmission electron microscopy (TEM) results. Secondary ion mass spectroscopy (SIMS) profiles confirmed the incorporation of Mg inside the QD layers, and the HRXRD analysis revealed that there is approximately 32% Mg in the ZnMgTe QDs. The presence of Mg contributes to higher scattering intensity of the HRXRD, leading to the observation of higher order superlattice peaks in both the (004) and (002) reflections. The distribution of scattered intensity in the reciprocal space map (RSM) shows that the diffuse scattered intensity is elongated along the q x axis, indicating a vertical correlation of the dots, which is found to be less defined for the sample with larger periodicity. The diffuse scattered intensity is also found to be weakly correlated along the q z direction indicating a weak lateral correlation of the dots.

Synthesis of Pb(II Imprinted Carboxymethyl Chitosan and the Application as Sorbent for Pb(II Ion

Directory of Open Access Journals (Sweden)

Abu Masykur

2014-07-01

Full Text Available The aims of this research is to synthesize Pb(II imprinted polymers with carboxymethyl chitosan (CMC as polymers and bisphenol A diglycidyl ether (BADGE as cross-linker (Pb-IIP. Chitosan (CTS, non imprinted polymer (NIP and Pb-IIP were characterized using infrared (IR spectroscopy, X-ray diffraction (XRD, surface area analyzer (SAA, scanning electron microscopy (SEM, and energy dispersive X-ray (EDX spectroscopy. The result showed that the adsorption was optimum at pH 5 and contact time of 250 min. Adsorption of Pb(II ion with all of adsorbents followed pseudo-second order kinetic equation. Adsorption of Pb(II ion on CTS followed Freundlich isotherm while that on NIP and Pb-IIP followed the Langmuir adsorption isotherm. The adsorbent of Pb-IIP give higher capacity than the NIP and CTS. Adsorption capacity of Pb-IIP, NIP and CTS were 167.1, 128.9 and 76.1 mg/g, respectively. NIP gave higher adsorption selectivity for Pb(II/Ni(II and Pb(II/Cu(II, whereas Pb-IIP showed higher adsorption selectivity for Pb(II/Cd(II.The hydrogen bonding dominated interaction between Pb(II ion on NIP and Pb-IIP.

Chemically modified activated carbon with 1-acylthiosemicarbazide for selective solid-phase extraction and preconcentration of trace Cu(II), Hg(II) and Pb(II) from water samples.

Science.gov (United States)

Gao, Ru; Hu, Zheng; Chang, Xijun; He, Qun; Zhang, Lijun; Tu, Zhifeng; Shi, Jianping

2009-12-15

A new sorbent 1-acylthiosemicarbazide-modified activated carbon (AC-ATSC) was prepared as a solid-phase extractant and applied for removing of trace Cu(II), Hg(II) and Pb(II) prior to their determination by inductively coupled plasma optical emission spectrometry (ICP-OES). The separation/preconcentration conditions of analytes were investigated, including effects of pH, the shaking time, the sample flow rate and volume, the elution condition and the interfering ions. At pH 3, the maximum static adsorption capacity of Cu(II), Hg(II) and Pb(II) onto the AC-ATSC were 78.20, 67.80 and 48.56 mg g(-1), respectively. The adsorbed metal ions were quantitatively eluted by 3.0 mL of 2% CS(NH2)2 and 2.0 mol L(-1) HCl solution. Common coexisting ions did not interfere with the separation. According to the definition of IUPAC, the detection limits (3sigma) of this method for Cu(II), Hg(II) and Pb(II) were 0.20, 0.12 and 0.45 ng mL(-1), respectively. The relative standard deviation under optimum conditions is less than 4.0% (n=8). The prepared sorbent was applied for the preconcentration of trace Cu(II), Hg(II) and Pb(II) in certified and water samples with satisfactory results.

Efficient removal of Co(II) from aqueous solution by titanate sodium nanotubes

Institute of Scientific and Technical Information of China (English)

Dong-Mei Li; Ning Liu; Fei-Ze Li; Jia-Li Liao; Ji-Jun Yang; Bing Li; Yun-Ming Chen; Yuan-You Yang; Jin-Song Zhang; Jun Tang

2016-01-01

In this paper, a novel material for Co(II) adsorption, titanate sodium nanotubes (Na2Ti2O5-NTs) were synthesized and characterized, and then they were used to remove Co(II) from aqueous solution and compared with titanic acid nanotubes (H2Ti2O5-NTs) and potassium hexatitanate whiskers (K2Ti6O13). The results showed that the adsorption of Co(II) on the materials was dependent on pH values and was a spontaneous, endothermic process. Specifically, Na2Ti2O5-NTs exhibited much more efficient ability to adsorb Co(II) from aqueous solution, with the maximum adsorption capacity of 85.25 mg/g. Furthermore, Na2Ti2O5-NTs could selectively adsorb Co(II) from aque-ous solution containing coexisting ions (Na+, K+, Mg2+, and Ca2+). The results suggested that Na2Ti2O5-NTs were potential effective adsorbents for removal of Co(II) or cobalt-60 from wastewater.

Enhanced biosorption of mercury(II) and cadmium(II) by cold-induced hydrophobic exobiopolymer secreted from the psychrotroph Pseudomonas fluorescens BM07

Energy Technology Data Exchange (ETDEWEB)

Zamil, Sheikh Shawkat; Choi, Mun Hwan; Song, Jung Hyun; Park, Hyunju; Xu, Ju; Yoon, Sung Chul [Gyeongsang National Univ., Jinju (Korea). Nano-Biomaterials Science Lab.; Chi, Ki-Whan [Ulsan Univ. (Korea). Dept. of Chemistry

2008-09-15

The cells of psychrotrophic Pseudomonas fluorescens BM07 were found to secrete large amounts of exobiopolymer (EBP) composed of mainly hydrophobic (water insoluble) polypeptide(s) (as contain {proportional_to}50 mol% hydrophobic amino acids, lacking cysteine residue) when grown on fructose containing limited M1 medium at the temperatures as low as 0-10 C but trace amount at high (30 C, optimum growth) temperature. Two types of nonliving BM07 cells (i.e., cells grown at 30 C and 10 C) as well as the freeze-dried EBP were compared for biosorption of mercury (Hg(II)) and cadmium (Cd(II)). The optimum adsorption pH was found 7 for Hg(II) but 6 for Cd(II), irrespective of the type of biomass. Equilibrium adsorption data well fitted the Langmuir adsorption model. The maximum adsorption (Q{sub max}) was 72.3, 97.4, and 286.2 mg Hg(II)/g dry biomass and 18.9, 27.0, and 61.5 mg Cd(II)/g dry biomass for cells grown at 30 C and 10 C and EBP, respectively, indicating major contribution of heavy metal adsorption by cold-induced EBP. Mercury(II) binding induced a significant shift of infrared (IR) amide I and II absorption of EBP whereas cadmium(II) binding showed only a very little shift. These IR shifts demonstrate that mercury(II) and cadmium(II) might have different binding sites in EBP, which was supported by X-ray diffraction and differential scanning calorimetric analysis and sorption results of chemically modified biomasses. This study implies that the psychrotrophs like BM07 strain may play an important role in the bioremediation of heavy metals in the temperate regions especially in the inactive cold season. (orig.)

Indirect complexometric determination of mercury(II) using potassium bromide as selective masking agent

International Nuclear Information System (INIS)

Sreekumar, N.V.; Nazareth, R.A.; Narayana, B.; Hegde, P.; Manjunatha, B.R.

2002-01-01

A complexometric method for the determination of mercury in presence of other metal ions based on the selective masking ability of potassium bromide towards mercury is described. Mercury(II) present in a given sample solution is first complexed with a known excess of EDTA and the surplus EDTA is titrated against zinc sulfate solution at pH 5-6 using xylenol orange as the indicator. A known excess of 10 % solution of potassium bromide is then added and the EDTA released from Hg-EDTA complex is titrated against standard zinc sulfate solution. Reproducible and accurate results are obtained for 8 mg to 250 mg of mercury(II) with a relative error ±0.28 % and standard deviations /leg 0.5 mg. The interference of various ions is studied. This method was applied to the determination of mercury(II) in its alloys. (author)

Discharge behaviour of Mg-Al-Pb and Mg-Al-Pb-In alloys as anodes for Mg-air battery

International Nuclear Information System (INIS)

Wang, Naiguang; Wang, Richu; Peng, Chaoqun; Peng, Bing; Feng, Yan; Hu, Chengwang

2014-01-01

Highlights: • We investigate the effect of indium on the discharge behaviour of Mg-Al-Pb alloy. • We evaluate the performance of Mg-air batteries with Mg-Al-Pb and Mg-Al-Pb-In anodes. • We analyze the activation mechanism of Mg-Al-Pb-In alloy in the discharge process. - Abstract: The discharge behaviour of Mg-Al-Pb and Mg-Al-Pb-In alloys in 3.5 wt.% NaCl solution is investigated by electrochemical techniques, and compared with that of pure magnesium. The results show that Mg-Al-Pb-In alloy provides a more negative potential and exhibits a higher utilization efficiency in contrast with Mg-Al-Pb alloy and pure magnesium during the half-cell test at a large current density, and gives desirable discharge performance when used as anode for Mg- air battery. The peak power density of the Mg-air battery with Mg-Al-Pb-In anode is 94.5 mW cm −2 , which is comparable with those of Mg-H 2 O 2 semi-fuel batteries. Moreover, the activation mechanism of Mg-Al-Pb-In alloy during the discharge process is also analyzed

Effects of nickel(II) addition on the activity of activated sludge microorganisms and activated sludge process

International Nuclear Information System (INIS)

Ong, Soon-An; Toorisaka, Eiichi; Hirata, Makoto; Hano, Tadashi

2004-01-01

The effects of Ni(II) in a synthetic wastewater on the activity of activated sludge microorganisms and sequencing batch reactor (SBR) treatment process were investigated. Two parallel lab-scale SBR systems were operated. One was used as a control unit, while the other received Ni(II) concentrations equal to 5 and 10 mg/l. The SBR systems were operated with FILL, REACT, SETTLE, DRAW and IDLE modes in the time ratio of 0.5:3.5:1.0:0.75:0.25 for a cycle time of 6 h. The addition of Ni(II) into SBR system caused drastically dropped in TOC removal rate (k) and specific oxygen uptake rate (SOUR) by activated sludge microorganisms due to the inhibitory effects of Ni(II) on the bioactivity of microorganisms. The addition of 5 mg/l Ni(II) caused a slight reduction in TOC removal efficiency, whereas 10 mg/l Ni(II) addition significantly affected the SBR performance in terms of suspended solids and TOC removal efficiency. Termination of Ni(II) addition led to almost full recovery of the bioactivity in microorganisms as shown in the increase of specific oxygen uptake rate (SOUR) and SBR treatment performance

The effect of the MgO buffer layer thickness on magnetic anisotropy in MgO/Fe/Cr/MgO buffer/MgO(001)

Energy Technology Data Exchange (ETDEWEB)

Kozioł-Rachwał, Anna, E-mail: a.koziolrachwal@aist.go.jp [National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki 305-8568 (Japan); AGH University of Science and Technology, Faculty of Physics and Applied Computer Science, al. Mickiewicza 30, 30-059 Kraków (Poland); Nozaki, Takayuki; Zayets, Vadym; Kubota, Hitoshi; Fukushima, Akio; Yuasa, Shinji [National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki 305-8568 (Japan); Suzuki, Yoshishige [National Institute of Advanced Industrial Science and Technology, Spintronics Research Center, Tsukuba, Ibaraki 305-8568 (Japan); Graduate School of Engineering Science, Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan)

2016-08-28

The relationship between the magnetic properties and MgO buffer layer thickness d was studied in epitaxial MgO/Fe(t)/Cr/MgO(d) layers grown on MgO(001) substrate in which the Fe thickness t ranged from 0.4 nm to 1.1 nm. For 0.4 nm ≤ t ≤ 0.7 nm, a non-monotonic coercivity dependence on the MgO buffer thickness was shown by perpendicular magneto-optic Kerr effect magnetometry. For thicker Fe films, an increase in the buffer layer thickness resulted in a spin reorientation transition from perpendicular to the in-plane magnetization direction. Possible origins of these unusual behaviors were discussed in terms of the suppression of carbon contamination at the Fe surface and changes in the magnetoelastic anisotropy in the system. These results illustrate a method to control magnetic anisotropy in MgO/Fe/Cr/MgO(d) via an appropriate choice of MgO buffer layer thickness d.

Removal of Pb(II) from aqueous solution by natural and synthetic ...

African Journals Online (AJOL)

The point of zero charge values of 9.57 and 8.20 were obtained by mass titration method for synthetic and natural calcite, respectively. The maximum adsorption capacities of 200 mg/g and 150 mg/g Pb(II) of synthetic calcite and natural calcite were obtained at initial lead loading of 1200 mg/L at 25±2 °C, respectively.

Biosorption of Cu(II) onto agricultural materials from tropical regions

KAUST Repository

Acheampong, Mike A.

2011-04-26

Background: In Ghana, the discharge of untreated gold mine wastewater contaminates the aquatic systems with heavy metals such as copper (Cu), threatening ecosystem and human health. The undesirable effects of these pollutants can be avoided by treatment of the mining wastewater prior to discharge. In this work, the sorption properties of agricultural materials, namely coconut shell, coconut husk, sawdust and Moringa oleifera seeds for Cu(II) were investigated. Results: The Freundlich isotherm model described the Cu(II) removal by coconut husk (R2 = 0.999) and sawdust (R2 = 0.993) very well and the Cu(II) removal by Moringa oleifera seeds (R2 = 0.960) well. The model only reasonably described the Cu(II) removal by coconut shell (R2 = 0.932). A maximum Cu(II) uptake of 53.9 mg g-1 was achieved using the coconut shell. The sorption of Cu(II) onto coconut shell followed pseudo-second-order kinetics (R2 = 0.997). FTIR spectroscopy indicated the presence of functional groups in the biosorbents, some of which were involved in the sorption process. SEM-EDX analysis confirmed an exchange of Mg(II) and K(I) for Cu(II) on Moringa oleifera seeds and K(I) for Cu(II) on coconut shell. Conclusion: This study shows that coconut shell can be an important low-cost biosorbent for Cu(II) removal. The results indicate that ion exchange, precipitation and electrostatic forces were involved in the Cu(II) removal by the biosorbents investigated. © 2011 Society of Chemical Industry.

Microstructural evolution in Mg-rich Mg-Zn-Y alloys

International Nuclear Information System (INIS)

Biswas, T.; Ranganathan, S.; Nair, S.; Bajargan, G.

2005-01-01

Mg-rich Mg-Zn-Y alloys with nominal compositions Mg 97 Zn 1 Y 2 , Mg 97 Zn 2 Y 1 , Mg 92 Zn 6.5 Y 1.5 and Mg 97-x Zn 1 Y 2 Zr x have been chosen for the present study. These alloys are prepared by using sand casting mold. The sand cast alloys are remelted and subjected to copper mold casting and melt spinning techniques. The effect of cooling rate on microstructures was studied. It is observed that the size of the precipitates decreases with an increase of cooling rate. The formation of nano precipitates results in higher strength of the alloy as compared to the conventional alloys. The microstructures of melt spun ribbons are compared with RS/PM (rapidly solidified power metallurgy) Mg 97 Zn 1 Y 2 alloy, obtained from a different source. (author)

Synthesis of amino functionalized magnetic graphenes composite material and its application to remove Cr(VI), Pb(II), Hg(II), Cd(II) and Ni(II) from contaminated water

International Nuclear Information System (INIS)

Guo, Xiaoyao; Du, Bin; Wei, Qin; Yang, Jian; Hu, Lihua; Yan, Liangguo; Xu, Weiying

2014-01-01

Highlights: • Graphenes magnetic composite nanoparticles (Fe 3 O 4 -GS) were used to adsorb metal ions. • The adsorption of metal ions onto Fe 3 O 4 -GS could be well interpreted by the Freundlich equation. • The adsorption of metal ions onto Fe 3 O 4 -GS fit pseudo-second order kinetic model. • Thermodynamic studies illustrated that the adsorption process was endothermic and spontaneous in nature. - Abstract: In the present study, a kind of graphenes magnetic material (Fe 3 O 4 -GS) was prepared by compositing graphene sheet with ferroferric oxide, and shown to be effictive for removing Cr(VI), Pb(II), Hg(II), Cd(II) and Ni(II) ions from aqueous solution. The synthesized sorbent was characterized by SEM, TEM, FTIR, XRD, XPS and BET, respectively. The pH ZPC value of the sorbent was estimated to be 3.5 by alkaline-titration methods. Fe 3 O 4 -GS can be simply recovered from water with magnetic separation at low magnetic field within one minute. The sorption capacities of the metals were 17.29, 27.95, 23.03, 27.83 and 22.07 mg g −1 for Cr(VI), Pb(II), Hg(II), Cd(II) and Ni(II), respectively. Kinetic data showed good correlation with pseudo-second-order equation and the Freundlich model was found to fit for the isotherm data of all the heavy metal ions. It was found that the metals sorption was accomplished mainly via chelation or ion exchange. The results of thermodynamic studies illustrate that the adsorption process was endothermic and spontaneous in nature

Loess clay based copolymer for removing Pb(II) ions

International Nuclear Information System (INIS)

He, Yu-Feng; Zhang, Ling; Wang, Rong-Min; Li, Hui-Ru; Wang, Yan

2012-01-01

Highlights: ► The loess clay based copolymer was prepared using functional monomers. ► Characterization of the polymer adsorbent and the raw material were carried out. ► The adsorption behavior of the complex for Pb(II) ions was evaluated. ► The removal rate of Pb(II) got to 99% and the adsorption capacity got to 356.9 mg/g. - Abstract: Functional monomers, such as acrylic acid and 2-hydroxyethyl methacrylate were supported into loess clay in situ polymerization, which afforded loess clay based copolymer (LC/PAAHM), a new kind of polymer adsorbent for removing Pb(II) ions from aqueous solution. Characterization of the polymer adsorbent was carried out by different sophisticated methods, such as Fourier transformation infrared spectrometry (FTIR), scanning electron microscopy (SEM), X-ray diffractometry (XRD), thermogravimetric analysis (TGA), and Zetasizer. Batch experiments were carried out to evaluate the factors affecting the removal efficiency, in which the pH, the adsorbent dosage, temperature and initial Pb(II) concentration all found in positive relevance to the increase of Pb(II) removal efficiency. The removal rate of Pb(II) got to 99% at room temperature and the adsorption capacity got to 356.9 mg/g. The pseudo-first-order and pseudo-second-order kinetic models were applied to test the experimental data, and Langmuir and Freundlich models have been applied to study the adsorption equilibrium, respectively.

Productino of KSR-III Airglow Photometers to Measure MUV Airglows of the Upper Atmosphere Above the Korean Peninsular

Directory of Open Access Journals (Sweden)

T. H. Oh

2002-12-01

Full Text Available We have constructed two flight models of airglow photometer system (AGP to be onboard Korea Sounding Rocket-III (KSR-III for detection of MUV dayglow above the Korean peninsular. The AGP system is designed to detect dayglow emissions of OI 2972 Å, N_2 VK (0,6 2780Å, N_2 2PG 3150Å and background 3070Å toward the horizon at altitudes between 100 km and 300 km. The AGP system consists of a photometer body, a baffle, an electronic control unit and a battery unit. The MUV dayglow emissions enter through a narrow band interference filter and focusing lens of the photometer, which contains an ultraviolet sensitive photomultiplier tube. The photometer is equipped with an in-flight calibration light source on a circular plane that will rotate at the rocket's apogee. A baffle tube is installed at the entry of the photometer in order to block strong scattering lights from the lower atmosphere. We have carried out laboratory measurements of sensitivity and in-flight calibration light source for the AGP flight models. Although absolute sensitivities of the AGP flight models could not be determined in the country, relative sensitivities among channels are well measured so that observation data during rocket flight in the future can be analyzed with confidence.

Batch adsorptive removal of Fe(III), Cu(II) and Zn(II) ions in aqueous and aqueous organic–HCl media by Dowex HYRW2-Na Polisher resin as adsorbents

OpenAIRE

Aboul-Magd, Abdul-Aleem Soliman; Al-Husain, Salwa Al-Rashed; Al-Zahrani, Salma Ahmed

2016-01-01

Of the metal ions in tap, Nile, waste and sea water samples and some ores were carried out. Removal of heavy metal ions such as Fe(III), Cd(II), Zn(II), Cu(II), Mn(II), Mg(II), and Pb(II) from water and wastewater is obligatory in order to avoid water pollution. Batch shaking adsorption experiments to evaluate the performance of nitric and hydrochloric acid solutions in the removal of metal ions by cation exchange resin at the same conditions for both, such as the effect of initial metal ion ...

Adsorption of platinum(IV) and palladium(II) from aqueous solution by thiourea-modified chitosan microspheres

International Nuclear Information System (INIS)

Zhou Limin; Liu Jinhui; Liu Zhirong

2009-01-01

The chitosan microparticles were prepared using the inverse phase emulsion dispersion method and modified with thiourea (TCS). TCS was characterized by scanning electron microscope (SEM), the Fourier transform infrared (FT-IR) spectra, sulfur elemental analysis, specific surface area and pore diameter. The effects of various parameters, such as pH, contact time, initial concentration and temperature, on the adsorption of Pt(IV) and Pd(II) by TCS were investigated. The results showed that the maximum adsorption capacity was found at pH 2.0 for both Pt(IV) and Pd(II). TCS can selectively adsorb Pt(IV) and Pd(II) from binary mixtures with Cu(II), Pb(II), Cd(II), Zn(II), Ca(II), and Mg(II). The adsorption reaction followed the pseudo-second-order kinetics, indicating the main adsorption mechanism of chemical adsorption. The isotherm adsorption equilibrium was well described by Langmuir isotherms with the maximum adsorption capacity of 129.9 mg/g for Pt(IV) and 112.4 mg/g for Pd(II). The adsorption capacity of both Pt(IV) and Pd(II) decreased with temperature increasing. The negative values of enthalpy (ΔH o ) and Gibbs free energy (ΔG o ) indicate that the adsorption process is exothermic and spontaneous in nature. The adsorbent was stable without loss of the adsorption capacity up to at least 5 cycles and the desorption efficiencies were above 95% when 0.5 M EDTA-0.5 M H 2 SO 4 eluent was used. The results also showed that the preconcentration factor for Pt(IV) and Pd(II) was 196 and 172, respectively, and the recovery was found to be more than 97% for both precious metal ions.

Boletus edulis loaded with γ-Fe2O3 nanoparticles as a magnetic sorbent for preconcentration of Co(II) and Sn(II) prior to their determination by ICP-OES.

Science.gov (United States)

Ozdemir, Sadin; Serkan Yalcin, M; Kilinc, Ersin; Soylak, Mustafa

2017-12-20

The authors show that the fungus Boletus edulis loaded with γ-Fe 2 O 3 nanoparticles is a viable sorbent for magnetic solid phase extraction of trace levels of Co(II) and Sn(II). The surface structure of immobilized magnetized B. edulis was characterized by FT-IR, SEM and EDX. Experimental parameters were optimized. Following elution with 1 M HCl, the ions were quantified by ICP-OES. The limits of detection are 21 pg·mL -1 for Co(II), and 19 pg·mL -1 for Sn(II). The preconcentration factors are 100 for both ions. The sorption capacities of the sorbent are 35.8 mg·g -1 for Co(II) and 29.6 mg·g -1 for Sn(II). The method was applied to the analysis of certificated reference materials and gave ≥95% recoveries with low RSDs. It was also successfully applied to the quantification of Co(II) and Sn(II) in spiked environmental and food samples. Graphical abstract The fungus Boletus edulis loaded with γ-Fe 2 O 3 nanoparticles is a viable biosorbent for magnetic solid phase extraction (MSPE) of trace levels of Co(II) and Sn(II). The surface structure of immobilized magnetized B. edulis was characterized by FT-IR, SEM and EDX. Experimental parameters were optimized.

Role of dopants in LiF:Mg,Cu, LiF:Mg,P and LiF:Mg,Cu,P detectors

International Nuclear Information System (INIS)

Mohammadi, Kh.; Moussavi Zarandi, A.; Afarideh, H.; Shahmaleki, S.

2013-01-01

In this study, electronic structure of LiF crystal doped with Mg,Cu,P impurities was studied with WIEN2k code on the basis of FPLAPW+lo method. Results show that in Mg-doped LiF composition, an electronic trap was created with impurity concentration of 1.56% and 3.125%. In this condition, the electronic trap with increasing the percentage of the impurities up to 4.687% is annihilated. It was found, that by doping of Mg and Cu or P simultaneously, a hole-trap is created in valence band. It was realized that in LiF:Mg,Cu, LiF:Mg,P and LiF:Mg,Cu,P, Cu impurity and Li atom, have a key role in creation of levels which lead to create electronic and hole traps. Mg impurity and F atom, only have a role in creation of electronic traps. In addition, P impurity has a main role in creation of the electronic and hole traps in LiF:Mg,Cu,P. The activation energy of electronic and hole trap in LiF:Mg,Cu, LiF:Mg,P and LiF:Mg,Cu,P crystalline lattice were obtained as 0.3 and 5.5 eV, 0.92 and 3.4 eV and 0.75 and 3.1 eV, respectively. - Graphical abstract: Figure (a) and (b) shows changes in electronic structure and band gap energy of LiF crystal due to presence of Mg and Cu, Mg and P ions respectively. - Highlights: • Electronic structure of LiF, LiF:Mg,Cu, LiF:Mg,P and LiF:Mg,Cu,P materials were studied with WIEN2K code. • In LiF:Mg,Cu and LiF:Mg,Cu,P, Li atom and Cu impurity have a key role in creation of levels. • F atom and Mg impurity only have a role in creation of electronic traps. • In LiF:Mg,Cu,P, P impurity has a main role in creation of electronic and hole traps

Fluorimetric determination of copper(II) in aqueous solution using lucifer yellow CH as selective metal reagent

Energy Technology Data Exchange (ETDEWEB)

Mayr, T.; Wencel, D.; Werner, T. [Univ. of Regensburg (Germany) Inst. of Analytical Chemistry, Chemo- and Biosensors

2001-09-01

Lucifer yellow CH is shown to be a highly selective fluorescent reagent for the determination of Cu(II) in the {mu}g L{sup -1} concentration range. The fluorophore is statically quenched by Cu(II); the carbohydrazide group was assigned as the complexing part of the dye molecule. A total range of Cu(II) determination from 0.06 mg L{sup -1} (1 {mu}mol L{sup -1}) to 6.3 mg L{sup -1} (100 {mu}mol L{sup -1}) with a limit of detection of 0.019 mg L{sup -1} (0.3 {mu}mol L{sup -1}) was obtained, along with surprisingly high selectivity. There was no interference from alkaline and earth alkaline metal ions. The cross sensitivity to heavy metal ions was evaluated by the separate solution method and by competitive binding experiments. Calibration plots are shown for Cu(II) determination at different pH and the dissociation constant was determined. The application of the reagent was demonstrated by the determination of the Cu(II) content of tap water samples. (orig.)

IGF-II receptors in luminal and basolateral membranes isolated from pars convoluta and pars recta of rabbit proximal tubule

DEFF Research Database (Denmark)

Jacobsen, Christian; Jessen, H; Flyvbjerg, A

1995-01-01

the inhibitory effect of beta-galactosidase. Analyses of 125I-IGF-II binding curves in the presence of beta-galactosidase or D-mannose 6-phosphate demonstrated that none of these compounds changed the binding affinity of 125I-IGF-II for the membrane vesicles. The IGF-II/M6P receptor content in the luminal...... membranes was in the range 0.21-0.34 pmol IGF-II/M6P receptor per mg protein and very low compared to 2.27-2.86 pmol IGF-II/M6P receptor per mg protein in basolateral membranes. Udgivelsesdato: 1995-Apr-12...

Comparative study of adsorption properties of Turkish fly ashes II. The case of chromium (VI) and cadmium (II)

International Nuclear Information System (INIS)

Bayat, Belgin

2002-01-01

The purpose of the study described in this paper was to compare the removal of Cr(VI) and Cd(II) from an aqueous solution using two different Turkish fly ashes; Afsin-Elbistan and Seyitomer as adsorbents. The influence of four parameters (contact time, solution pH, initial metal concentration in solution and ash quality) on the removal at 20±2 deg. C was studied. Fly ashes were found to have a higher adsorption capacity for the adsorption of Cd(II) as compared to Cr(VI) and both Cr(VI) and Cd(II) required an equilibrium time of 2 h. The adsorption of Cr(VI) was higher at pH 4.0 for Afsin-Elbistan fly ash (25.46%) and pH 3.0 for Seyitomer fly ash (30.91%) while Cd(II) was adsorbed to a greater extent (98.43% for Afsin-Elbistan fly ash and 65.24% for Seyitomer fly ash) at pH 7.0. The adsorption of Cd(II) increased with an increase in the concentrations of these metals in solution while Cr(VI) adsorption decreased by both fly ashes. The lime (crystalline CaO) content in fly ash seemed to be a significant factor in influencing Cr(VI) and Cd(II) ions removal. The linear forms of the Langmuir and Freundlich equations were utilised for experiments with metal concentrations of 55±2 mg/l for Cr(VI) and 6±0.2 mg/l for Cd(II) as functions of solution pH (3.0-8.0). The adsorption of Cr(VI) on both fly ashes was not described by both the Langmuir and Freundlich isotherms while Cd(II) adsorption on both fly ashes satisfied only the Langmuir isotherm model. The adsorption capacities of both fly ashes were nearly three times less than that of activated carbon for the removal of Cr(VI) while Afsin-Elbistan fly ash with high-calcium content was as effective as activated carbon for the removal of Cd(II). Therefore, there are possibilities for use the adsorption of Cd(II) ions onto fly ash with high-calcium content in practical applications in Turkey

Preparation and Hydrogen Storage Properties of Mg-Rich Mg-Ni Ultrafine Particles

Directory of Open Access Journals (Sweden)

Jianxin Zou

2012-01-01

Full Text Available In the present work, Mg-rich Mg-Ni ultrafine powders were prepared through an arc plasma method. The phase components, microstructure, and hydrogen storage properties of the powders were carefully investigated. It is found that Mg2Ni and MgNi2 could be obtained directly from the vapor state reactions between Mg and Ni, depending on the local vapor content in the reaction chamber. A nanostructured MgH2 + Mg2NiH4 hydrogen storage composite could be generated after hydrogenation of the Mg-Ni ultrafine powders. After dehydrogenation, MgH2 and Mg2NiH4 decomposed into nanograined Mg and Mg2Ni, respectively. Thermogravimetry/differential scanning calorimetry (TG/DSC analyses showed that Mg2NiH4 phase may play a catalytic role in the dehydriding process of the hydrogenated Mg ultrafine particles.

Removal of Pb(II) from aqueous solution using modified and unmodified kaolinite clay

International Nuclear Information System (INIS)

Jiang Mingqin; Wang Qingping; Jin Xiaoying; Chen Zuliang

2009-01-01

Modified kaolinite clay with 25% (w/w) aluminium sulphate and unmodified kaolin were investigated as adsorbents to remove Pb(II) from aqueous solution. The results show that amount of Pb(II) adsorbed onto modified kaolin (20 mg/g) was more than 4.5-fold than that adsorbed onto unmodified kaolin (4.2 mg/g) under the optimized condition. In addition, the linear Langmuir and Freundlich models were used to describe equilibrium isotherm. It is observed that the data from both adsorbents fitted well to the Langmuir isotherm. The kinetic adsorption of modified and unmodified kaolinite clay fitted well to the pseudo-second-order model. Furthermore, both modified and unmodified kaolinite clay were characterized by X-ray diffraction, Fourier transform infrared (FT-IR) and scanning electron microscope (SEM). Finally, both modified and unmodified kaolinite clay were used to remove metal ions from real wastewater, and results show that higher amount of Pb(II) (the concentration reduced from 178 to 27.5 mg/L) and other metal ions were removed by modified kaolinite clay compared with using unmodified adsorbent (the concentration reduced from 178 to 168 mg/L).

Copper(II) manganese(II) orthophosphate, Cu_0.5Mn_2.5(PO₄)₂

DEFF Research Database (Denmark)

Warner, Terence Edwin; Bond, Andrew; Foghmoes, Søren Preben Vagn

2011-01-01

The title compound, Cu0.5Mn2.5(PO4)2, is a copper-manganese phosphate solid solution with the graftonite-type structure, (Mn,Fe,Ca,Mg)3(PO4)2. The structure has three distinct metal cation sites, two of which are occupied exclusively by MnII, and one of which accommodates CuII. Incorporation of C......II into the structure distorts the coordination geometry of the metal cation site from 5-coordinate square-pyramidal towards 4-coordinate flattened tetrahedral, and serves to contract the structure principally along the c axis....

Design and characterization of sulfide-modified nanoscale zerovalent iron for cadmium(II) removal from aqueous solutions

Science.gov (United States)

Lv, Dan; Zhou, Xiaoxin; Zhou, Jiasheng; Liu, Yuanli; Li, Yizhou; Yang, Kunlun; Lou, Zimo; Baig, Shams Ali; Wu, Donglei; Xu, Xinhua

2018-06-01

Nanoscale zero-valent iron (nZVI) has high removal efficiency and strong reductive ability to organic and inorganic contaminants, but concerns over its stability and dispersity limit its application. In this study, nZVI was modified with sulfide to enhance Cd(II) removal from aqueous solutions. TEM and SEM analyses showed that sulfide-modified nZVI (S-nZVI) had a core-shell structure of nano-sized spherical particles, and BET results proved that sulfide modification doubled the specific surface area from 26.04 to 50.34 m2 g-1 and inhibited the aggregation of nZVI. Mechanism analysis indicated that Cd(II) was immobilized through complexation and precipitation. Cd(II) removal rate on nZVI was only 32% in 2 h, while complete immobilization could be achieved in 15 min on S-nZVI, and S-nZVI with an optimal S/Fe molar ratio of 0.3 offered a cadmium removal capacity of about 150 mg g-1 at pH 7 and 303 K. The process of Cd(II) immobilization on S-nZVI was fitted well with pseudo-second-order kinetic model, and the increase of temperature favored Cd(II) immobilization, suggesting an endothermic process. The presence of Mg2+ and Ca2+ hindered Cd(II) removal while Cu2+ did the opposite, which led to the order as Cu2+ > control > Mg2+ > Ca2+. The removal rate of 20 mg L-1 Cd(II) maintained a high level with the fluctuation of environmental conditions such as pH, ion strength and presence of HA. This study demonstrated that S-nZVI could be a promising adsorbent for Cd(II) immobilization from cadmium-contaminated water.

Re-examining the 26Mg(α ,α')26Mg reaction: Probing astrophysically important states in 26Mg

Science.gov (United States)

Adsley, P.; Brümmer, J. W.; Li, K. C. W.; Marín-Lámbarri, D. J.; Kheswa, N. Y.; Donaldson, L. M.; Neveling, R.; Papka, P.; Pellegri, L.; Pesudo, V.; Pool, L. C.; Smit, F. D.; van Zyl, J. J.

2017-11-01

Background: The 22Ne(α ,n )25Mg reaction is one of the neutron sources for the s process in massive stars. The properties of levels in 26Mg above the α -particle threshold control the strengths of the 22Ne(α ,n )25Mg and 22Ne(α ,γ )26Mg reactions. The strengths of these reactions as functions of temperature are one of the major uncertainties in the s process. Purpose: Information on the existence, spin, and parity of levels in 26Mg can assist in constraining the strengths of the 22Ne(α ,γ )26Mg and 22Ne(α ,n )25Mg reactions, and therefore in constraining s -process abundances. Methods: Inelastically scattered α particles from a 26Mg target were momentum-analyzed in the K600 magnetic spectrometer at iThemba LABS, South Africa. The differential cross sections of states were deduced from the focal-plane trajectory of the scattered α particles. Based on the differential cross sections, spin and parity assignments to states are made. Results: A newly assigned 0+ state was observed in addition to a number of other states, some of which can be associated with states observed in other experiments. Some of the deduced Jπ values of the states observed in the present study show discrepancies with those assigned in a similar experiment performed at RCNP Osaka. The reassignments and additions of the various states can strongly affect the reaction rate at low temperatures. Conclusion: The number, location, and assignment of levels in 26Mg that may contribute to the 22Ne+α reactions are not clear. Future experimental investigations of 26Mg must have an extremely good energy resolution to separate the contributions from different levels. Coincidence experiments of 26Mg provide a possible route for future investigations.

Rapid radioimmunoassay of human apolipoproteins C-II and C-III

Energy Technology Data Exchange (ETDEWEB)

Gustafson, S; Oestlund-Lindqvist, A M; Vessby, B [Uppsala Univ. (Sweden)

1984-06-01

Apolipoprotein (apo) C-II is an activator of lipoprotein lipase, while apo C-III has the ability to inhibit apo C-II activated lipolysis. In order to study further the relationship between lipoprotein lipase mediated hydrolysis and the serum concentrations of apo C-II and apo C-III radioimmunoassays for these apolipoproteins have been developed. Formalin-treated Staphylococcus aureus Cowan I was used for immunoprecipitation and were shown to give rapid uptake of immune complexes that could easily be harvested by centrifugation. The assays were shown to be sensitive (10 ..mu..g/1), specific, precise (inter- and intra-assay coefficients of variation below 10%), rapid (completed in less than 6 h) and simple to perform. Delipidation of serum and lipoproteins had no effect on the results, indicating that the immunologically active sites of apo C-II and apo C-III are exposed to the aqueous environment under assay conditions. Serum apo C-II and apo C-III levels of normolipidaemic subjects were approximately 25 mg/1 and 110 mg/1, respectively. Highly significant positive correlations were found between VLDL apo C-II and VLDL apo C-III, respectively, and VLDL triglycerides, VLDL cholesterol and total serum TG. There was also a highly significant correlation between the HDL cholesterol concentration and the HDL apo C-III concentration.

HYDROTALSIT Zn-Al-EDTA SEBAGAI ADSORBEN UNTUK POLUTAN ION Pb(II DI LINGKUNGAN Zn-Al-EDTA Hydrotalcite as Adsorbent for Pb(II Ion Pollutant in The Environment

Directory of Open Access Journals (Sweden)

Roto Roto

2015-07-01

Full Text Available ABSTRAK Polusi ion Pb(II di dalam lingkungan perairan cenderung naik seiring peningkatan jumlah industri smelter dan daur ulang aki bekas. Penelitian ini bertujuan untuk menguji kemampuan hidrotalsit Zn-Al-EDTA sebagai adsorben ion Pb(II dalam air secara mendalam. Hidrotalsit Zn-Al-NO3 disintesis dengan metode kopresipitasi dan hidrotermal pada temperatur 100 °C selama 15 jam. Hidrotalsit Zn-Al-EDTA diperoleh dengan penukaran ion. Keasaman larutan, kinetika dan kapasitas adsorpsi diteliti. Hidrotalsit Zn-Al-EDTA memiliki d003 sebesar 14,52 Å sementara Zn-Al-NO3 sebesar 8,90 Å. Spektra FTIR menunjukkan keberadaan serapan gugus C=O pada bilangan gelombang 1684,77 cm-1. Kondisi optimum adsorpsi ion Pb(II terjadi pada pH 4, waktu kontak 60 menit dan kapasitas adsorpsi diperoleh 2,07 mg/g pada konsentrasi awal 10 mg/L dengan berat adsorben 0,100 g. Adsorpsi ion Pb(II oleh hidrotalsit Zn-Al-EDTA mengikuti reaksi pseudo orde dua dengan tetapan laju adsorpsi sebesar 8,90 g mmol-1min-1. Adsorpsi ion Pb(II oleh Zn-Al-EDTA terjadi karena  pembentukan khelat Pb-EDTA di dalam struktur hidrotalsit. Hasil ini diharapkan mampu memberikan kontribusi yang lebih luas di dalam pengendalian konsentrasi Pb(II di lingkungan. ABSTRACT Polution by Pb(II ion in the water environment tends to increase due the increase in the number of lead smelter and lead acid battery recycling industries. This work aims at studying in details the ability of Zn-Al-EDTA hydrotalcite as adsorbent for Pb(II ion in the environment. The Zn-Al-NO3 hydrotalcite was synthesized first by coprecipitation method followed by hydrothermal treatment at 100 °C for 15 h. The Zn-Al-EDTA hydrotalcite was later obtained by ion exchange process. The solution pH, kinetics and adsorption capacity were studied. The XRD data showed that Zn-Al-EDTA and Zn-Al-NO3 hydrotalcites have d003 of 14.52 and 8.90 Å, respectively. The FTIR spectra suggested that C=O group was observed with absorption band at 1684

Removal of Fe(II) from tap water by electrocoagulation technique

International Nuclear Information System (INIS)

Ghosh, D.; Solanki, H.; Purkait, M.K.

2008-01-01

Electrocoagulation (EC) is a promising electrochemical technique for water treatment. In this work electrocoagulation (with aluminum as electrodes) was studied for iron Fe(II) removal from aqueous medium. Different concentration of Fe(II) solution in tap water was considered for the experiment. During EC process, various amorphous aluminum hydroxides complexes with high sorption capacity were formed. The removal of Fe(II) was consisted of two principal steps; (a) oxidation of Fe(II) to Fe(III) and (b) subsequent removal of Fe(III) by the freshly formed aluminum hydroxides complexes by adsorption/surface complexation followed by precipitation. Experiments were carried out with different current densities ranging from 0.01 to 0.04 A/m 2 . It was observed that the removal of Fe(II) increases with current densities. Inter electrode distance was varied from 0.005 to 0.02 m and was found that least inter electrode distance is suitable in order to achieve higher Fe(II) removal. Other parameters such as conductivity, pH and salt concentration were kept constant as per tap water quality. Satisfactory iron removal of around 99.2% was obtained at the end of 35 min of operation from the initial concentration of 25 mg/L Fe(II). Iron concentration in the solution was determined using Atomic absorption spectrophotometer. By products obtained from the electrocoagulation bath were analyzed by SEM image and corresponding elemental analysis (EDAX). Cost estimation for the electrocoagulation was adopted and explained well. Up to 15 mg/L of initial Fe(II) concentration, the optimum total cost was 6.05 US$/m 3 . The EC process for removing Fe(II) from tap water is expected to be adaptable for household use

Removal of cadmium (II) from aqueous solution: A comparative study of raw attapulgite clay and a reusable waste–struvite/attapulgite obtained from nutrient-rich wastewater

Energy Technology Data Exchange (ETDEWEB)

Wang, Hao [State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China); Wang, Xuejiang, E-mail: wangxj@tongji.edu.cn [State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China); Ma, Jinxing, E-mail: jinxing.ma@unsw.edu.au [School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW 2052 (Australia); Xia, Peng; Zhao, Jianfu [State Key Laboratory of Pollution Control and Resource Reuse, College of Environmental Science and Engineering, Tongji University, Shanghai 200092 (China)

2017-05-05

Highlights: • Both nutrient recovery and Cd(II) removal were achieved by MAP/APT. • The nutrient recovery process was used as a novel method of modification. • Compared with raw APT, MAP/APT enhanced Cd(II) adsorption capacity. • Cd(II) adsorption mechanisms from aqueous solution were extensively investigated. - Abstract: In this study, raw attapulgite (APT) and a novel adsorbent, struvite/attapulgite (MAP/APT) obtained from nutrient-rich wastewater treated by MgO modified APT, were applied as the absorbent for Cd(II) ion removal from aqueous solution. The two adsorbents were characterized by BET, SEM-EDS, XRD, FT-IR. Raw APT and MAP/APT separately presented the maximum Cd(II) adsorption capacities of 10.38 mg/g and 121.14 mg/g at pH of 5.45. The Cd(II) adsorption on raw APT and MAP/APT could be well fitted by Freundlich isotherm and Langmuir isotherm, respectively. Pseudo-second order equation was able to properly describe the kinetics of Cd(II) adsorption by raw APT and MAP/APT. The calculated thermodynamic parameters indicated that Cd(II) adsorption onto raw APT and MAP/APT were spontaneous and endothermic. An economic evaluation revealed that the treatment costs of the adsorption process by raw APT and MPA/APT were 0.013 $ per 1000 mg Cd and 0.004 $ per 1000 mg Cd, respectively.

Cd(II) removal and recovery enhancement by using acrylamide–titanium nanocomposite as an adsorbent

International Nuclear Information System (INIS)

Sharma, Ajit; Lee, Byeong-Kyu

2014-01-01

Graphical abstract: - Highlights: • Acrylamide doping initiated 10–20% increase in the particle size. • R-NH 2 Cd 2+ and Cd-O onto the nanocomposite improved Cd(II) adsorption. • Coexisting cations did not make any significant interference of Cd(II) removal. • Increased Ti nanoparticles leads to decrease in mass swelling of acrylamide. - Abstract: Acrylamide (AM) was in-situ doped into titanium during sol–gel reaction and used as an adsorbent for cadmium removal from aqueous solution. The resulting TiO 2 -AM nanocomposite was characterized by particle size distribution (PSD) and thermogravimetric analysis (TGA). After cadmium adsorption, the nanocomposite was also characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy/energy-dispersive X-ray (SEM/EDX) and X-ray photoelectron spectroscopy (XPS) analyses. The adsorption behavior of the nanocomposite was examined by kinetic and equilibrium studies in batch conditions. The maximum cadmium binding capacity of TiO 2 -AM was 322.58 mg g −1 at an optimum pH of 8.0, compared to 86.95 mg g −1 for nano-titanium. Cadmium sorption showed pseudo-second-order kinetics with a rate constant of 4.0 × 10 −4 and 9.4 × 10 −5 g mg −1 min −1 at an initial Cd(II) concentration of 100 and 500 mg L −1 , respectively. Cd (II) adsorption interference of cations (Pb 2+ , Cu 2+ , Co 2+ and Zn +2 ) and anions (Cl − , SO 4 2− , CO 3 2− ) at pH 8 was very nominal because of favorable complex formation of Cd(II) and amide. The Cd(II) adsorption of 27% that was achieved in the fifth cycle was regenerated with 0.05 N acidic solutions

Optical absorption and thermoluminescence in Mg O, Mg O:Ni and Mg O:Li irradiated at room temperature; Absorcion optica y termoluminiscencia en MgO, MgO:Ni y MgO:Li irradiados a temperatura ambiente

Energy Technology Data Exchange (ETDEWEB)

Delgado, L

1984-07-01

Optical absorption and thermoluminescence (TL) studies in Mg O, Mg O:Ni and Mg O:Li irradiated at room temperature are presented. In pure Mg O the thermal annihilation of Fe3+ by recombination with thermally released electrons at {approx} 90 and 175 degree centigree and the V center annealing by hole release up to 100 degree centigree cause the observed glow peaks at these temperatures. The TL excitation spectrum shows two maxima at 245 nm (electron center) and 288 nm (Fe3+). In Mg O:Ni X irradiation induces Fe{sup 2}+ {yields}- Fe{sup 3}+ and Ni{sup 2}+ {yields} Ni{sup 3}+ oxidations. Two TL emission bands centered at 110 degree centigree (red) and 80 o{sup C} (green) are assigned to electron release and their recombination at Fe{sup 3}+ and Ni{sup 3}+ respectively. In Mg O:Li two TL emission bands, one blue (430 nm) and the other red (730 nm) with excitation maxima at 245 nm (electron center) and 200 nm (hole center) respectively are observed. No V-center formation was detected in both Ni and Li doped samples. (Author) 42 refs.

Nonvolatile Memories Using Quantum Dot (QD) Floating Gates Assembled on II-VI Tunnel Insulators

Science.gov (United States)

Suarez, E.; Gogna, M.; Al-Amoody, F.; Karmakar, S.; Ayers, J.; Heller, E.; Jain, F.

2010-07-01

This paper presents preliminary data on quantum dot gate nonvolatile memories using nearly lattice-matched ZnS/Zn0.95Mg0.05S/ZnS tunnel insulators. The GeO x -cladded Ge and SiO x -cladded Si quantum dots (QDs) are self-assembled site-specifically on the II-VI insulator grown epitaxially over the Si channel (formed between the source and drain region). The pseudomorphic II-VI stack serves both as a tunnel insulator and a high- κ dielectric. The effect of Mg incorporation in ZnMgS is also investigated. For the control gate insulator, we have used Si3N4 and SiO2 layers grown by plasma- enhanced chemical vapor deposition.

Adsorption characteristics of cadmium(II) onto functionalized poly(hydroxyethylmethacrylate)-grafted coconut coir pith.

Science.gov (United States)

Anirudhan, Thayyath Sreenivasan; Divya, Lekshmi; Rijith, Sreenivasan

2010-07-01

This study explored the feasibility of utilizing a novel adsorbent, poly(hydroxyethylmethacrylate)-grafted coconut coir pith with carboxyl functionality (PGCP-COOH) for the removal of cadmium(II) from water and wastewater. Maximum removal of 99.9% was observed for an initial concentration of 25 mg/L at pH 6.0 and adsorbent dose of 2.0 g/L. The first-order reversible kinetic model and Langmuir isotherm model were resulted in high correlation coefficients and described well the adsorption of Cd(II) onto PGCP-COOH. The complete removal of 22.4 mg/L Cd(II) from fertilizer industry wastewater was achieved by 2.0 g/L PGCP-COOH. The reusability of the PGCP-COOH for several cycles was demonstrated using 0.1 M HCl solution.

Modeling and stabilities of Mg/MgH2 interfaces: A first-principles investigation

Directory of Open Access Journals (Sweden)

Jia-Jun Tang

2014-07-01

Full Text Available We have theoretically investigated the modeling and the structural stabilities of various Mg/MgH2 interfaces, i.e. Mg(101¯0/MgH2(210, Mg(0001/MgH2(101 and Mg(101¯0/MgH2(101, and provided illuminating insights into Mg/MgH2 interface. Specifically, the main factors, which impact the interfacial energies, are fully considered, including surface energies of two phases, mutual lattice constants of interface model, and relative position of two phases. The surface energies of Mg and MgH2, on the one hand, are found to be greatly impacting the interfacial energies, reflected by the lowest interfacial energy of Mg(0001/MgH2(101 which is comprised of two lowest energy surfaces. On the other hand, it is demonstrated that the mutual lattice constants and the relative position of two phases lead to variations of interfacial energies, thus influencing the interface stabilities dramatically. Moreover, the Mg-H bonding at interface is found to be the determinant of Mg/MgH2 interface stability. Lastly, interfacial and strain effects on defect formations are also studied, both of which are highly facilitating the defect formations. Our results provide a detailed insight into Mg/MgH2 interface structures and the corresponding stabilities.

Kajian Termodinamika Adsorpsi Hibrida Merkapto-Silika dari Abu Sekam Padi Terhadap Ion Co(II

Directory of Open Access Journals (Sweden)

Dwi Rasy Mujiyanti

2017-03-01

Full Text Available AbstrakTelah dilakukan penelitian tentang kajian termodinamika adsorpsi hibrida merkapto-silika dari abu sekam padi terhadap ion Co(II. Penelitian ini bertujuan untuk menentukan kapasitas dan energi adsorpsi hibrida merkapto-silika (HMS dan silika gel (SG terhadap ion Co(II. Pada penelitian ini, silika gel dibuat menggunakan natrium silikat dari abu sekam padi. Selanjutnya, senyawa organik 3-(trimetoksisilil-1-propantiol diimobilisasi pada SG menghasilkan HMS. Adsorben dikarakterisasi menggunakan difraktometer sinar-X dan spektrofotometer FTIR. Larutan Co(II kemudian dikontakkan dengan SG dan HMS pada variasi pH, waktu, dan konsentrasi awal. Hasil penelitian kapasitas adsorpsi yang diperoleh HMS hampir tiga kali lebih besar dibandingkan dengan SG, dengan besarnya kapasitas adsorpsi masing-masing yaitu 250,00 mg/g dan 90,91 mg/g. Sedangkan energi adsorpsi yang diperoleh adalah 51,69 KJ/mol untuk SG, dan 23,65 KJ/mol untuk HMS.Kata kunci : sekam padi, hibrida merkapto-silika, adsorpsi, ion Co(IIAbstractA research on the study of the thermodynamics of adsorption mercapto-silica hybrid from rice husk ash to the ions Co (II has been done. This study aims to determine capacity and energy adsorption of hybrid mercapto-silica (HMS and silica gel (SG to the ions Co (II . In this study, silica gel was made using sodium silicate from rice husk ash. Furthermore, the organic compound 3-(trimethoxysilil -1-prophantiol immobilized on SG to HMS produced. Adsorbents were characterized using X-ray diffraction and FTIR spectrophotometer. Solution of Co (II is then contacted with the SG and HMS at the variation of pH, time , and initial concentration. The results obtained by HMS adsorption capacity is almost three times larger than the SG, the magnitude of adsorption capacity of each is 250.00 mg / g and 90.91 mg / g . While the adsorption energy obtained is 51.69 KJ / mol for SG , and 23.65 KJ / mol for HMS.Keywords : rice husk, mercapto-silica hybrid , adsorption

Rapid adsorption of copper(II) and lead(II) by rice straw/Fe₃O₄ nanocomposite: optimization, equilibrium isotherms, and adsorption kinetics study.

Science.gov (United States)

Khandanlou, Roshanak; Ahmad, Mansor B; Fard Masoumi, Hamid Reza; Shameli, Kamyar; Basri, Mahiran; Kalantari, Katayoon

2015-01-01

Rice straw/magnetic nanocomposites (RS/Fe3O4-NCs) were prepared via co-precipitation method for removal of Pb(II) and Cu(II) from aqueous solutions. Response surface methodology (RSM) was utilized to find the optimum conditions for removal of ions. The effects of three independent variables including initial ion concentration, removal time, and adsorbent dosage were investigated on the maximum adsorption of Pb (II) and Cu (II). The optimum conditions for the adsorption of Pb(II) and Cu(II) were obtained (100 and 60 mg/L) of initial ion concentration, (41.96 and 59.35 s) of removal time and 0.13 g of adsorbent for both ions, respectively. The maximum removal efficiencies of Pb(II) and Cu(II) were obtained 96.25% and 75.54%, respectively. In the equilibrium isotherm study, the adsorption data fitted well with the Langmuir isotherm model. The adsorption kinetics was best depicted by the pseudo-second order model. Desorption experiments showed adsorbent can be reused successfully for three adsorption-desorption cycles.

Picroside I and Picroside II from Tissue Cultures of Picrorhiza kurroa

Science.gov (United States)

Ganeshkumar, Yamjala; Ramarao, Ajmera; Veeresham, Ciddi

2017-01-01

Background: Picrorhiza kurroa (PK) belongs to Scrophulariaceae family and is a representative endemic, medicinal herb, widely distributed throughout the higher altitudes of alpine Himalayas from west to east, between 3000 and 4500 m above mean sea level. Objective: The objective of the present study is to assess the production of picroside I and picroside II from tissue cultures of PK. Materials and Methods: Auxiliary shoot tips of PK were incubated in Murashige and Skoog medium supplemented with indole-3-butyric acid and kinetin phytohormones. The callus produced was collected at different time intervals and was processed for extraction of picroside I and picroside II followed by thin layer chromatography and high-performance liquid chromatography HPLC analysis. Results: The maximum growth index was found to be 5.109 ± 0.159 at 16-week-old callus culture. The estimation of picroside-I and picroside-II was carried out by (HPLC) analysis; quantity of secondary metabolite found to be 16.37 ± 0.0007 mg/g for PK-I and 6.34 ± 0.0012 mg/g for PK-II. Conclusion: This is the first attempt to produce the Picroside-I and II in large amount by the tissue culture technique. It can be observed that the method of callus culture can be used in production of secondary metabolites Picroside-I and II from PK SUMMARY Picrorhiza kurroa is a high value medicinal herb due to rich source of hepatoprotective metabolites, Picroside-I and Picroside-II. The medicinal importance of P. kurroa is due to its pharmacological properties like hepatoprotective, antioxidant (particularly in liver), antiallergic and antiasthamatic, anticancer activity particularly in liver and immunomodulatory. Shoot apices which were produced a good response was inoculated on selected medium i.e., on MS medium containing 2, 4 D (mg/l) + KN (1mg/l) for induction of callus. The initiation of callus was observed after 4weeks and it was light green and fragile Maximum growth was observed with 3% w/v of sucrose

Biosorption of lead (II and copper (II by biomass of some marine algae

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Chaisuksant, Y.

2004-09-01

Full Text Available Biosorption of heavy metal ions by algae is a potential technology for treating wastewater contaminated with heavy metals. Adsorption of lead (II and copper (II in aqueous solutions by some marine algae available in large quantities in Pattani Bay including Gracilaria fisheri, Ulva reticulata and Chaetomorpha sp. were investigated. The effect of pH on metal sorption of the algal biomass and the metal uptake capacity of the algal biomass comparing to that of synthetic adsorbents including activated carbon and siliga gel were studied by using batch equilibrium experiments. Each dried adsorbent was stirred in metal ions solutions with different pH or different concentration at room temperature for 24 hours and the residual metal ions were analysed using atomic absorption spectrophotometer. The initial concentrations of lead and copper ionswere 70 µg/l and 20 mg/l, respectively. It was found that the effect of pH on metal sorption was similar in each algal biomass. The metal uptake capacity increased as pH of the solution increased from 2.0 to 4.0 and reached a plateau at pH 5.0-7.0. The metal uptake capacities of each algal biomass were similar. At low concentrations of metal ions, the metal adsorption occurred rapidly while at higher metal concentration less metal adsorption by each algal biomass was observed. The metal adsorption of activated carbon and silica gel occurred gradually and was less than those of algal biomass. The equilibrium data of copper and lead ions fitted well to the Langmuir and Freundlich isotherm models. The maximum sorption capacity (Qm values (mean±SD of Chaetomorpha sp., U. reticulata, G. fisheri, activated carbon and silica gel for lead ions were 1.26±0.14, 1.19±0.14, 1.18±0.15, 1.14±0.11 and 1.15±0.12 mg/g, respectively. For copper adsorption, the Qm values for G. fisheri, U. reticulata and Chaetomorpha biomass were 15.87±1.03, 14.71±1.02 and 12.35± 1.03 mg/g, respectively. While those of activated carbon and

Sorption of Pb(II and Cu(II by low-cost magnetic eggshells-Fe3O4 powder

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Ren Jianwei

2012-01-01

Full Text Available This study explored the feasibility of using magnetic eggshell-Fe3O4 powder as adsorbent for the removal of Pb(II and Cu(II ions from aqueous solution. The metal ionsadsorption media interaction was characterized using XRD and FTIR. The effects of contact time, initial concentrations, temperature, solution pH and reusability of the adsorption media were investigated. The metal ions adsorption was fast and the amount of metal ions adsorbed increased with an increase in temperature, suggesting an endothermic adsorption. The kinetic data showed that the adsorption process followed the pseudo-second-order kinetic model. The optimal adsorption pH value was around 5.5 at which condition the equilibrium capacity was 263.2 mg/g for Pb(II and 250.0 for Cu(II. The adsorption equilibrium data fitted very well to the Langmuir and Freundlich adsorption isotherm models. The thermodynamics of Pb(II and Cu(II adsorption onto the magnetic eggshell-Fe3O4 powder indicated that the adsorption was spontaneous. The reusability study has proven that magnetic eggshell-Fe3O4 powder can be employed as a low-cost and easy to separate adsorbent.

Evaluation of the quality of guidelines for myasthenia gravis with the AGREE II instrument.

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Zhenchang Zhang

Full Text Available Clinical practice guidelines (CPGs are systematically developed statements to assist practitioners in making decisions about appropriate healthcare in specific clinical circumstances. The methodological quality of CPGs for myasthenia gravis (MG are unclear.To critically evaluate the methodological quality of CPGs for MG using AGREE II instrument.A systematical search strategy on PubMed, EMBASE, DynaMed, the National Guideline Clearinghouse (NGC and the Chinese Biomedical Literature database (CBM was performed on September 20th 2013. All guidelines related to MG were evaluated with AGREE II. The software used for analysis was SPSS 17.0.A total of 15 CPGs for MG met the inclusion criteria (12 CPGs in English, 3 CPGs in Chinese. The overall agreement among reviews was moderate or high (ICC >0.70. The mean scores (mean ± SD for al six domains were presented as follows: scope and purpose (60.93% ± 16.62%, stakeholder involvement (40.93% ± 20.04%, rigor of development (37.22% ± 30.46%, clarity of presentation (64.26% ± 16.36%, applicability (28.19% ± 20.56% and editorial independence (27.78% ± 28.28%. Compared with non-evidence-based CPGs, evidence-based CPGs had statistically significant higher quality scores for all AGREE II domains (P0.05. The quality scores of CPGs developed by NGC/AAN were higher than the quality scores of CPGs developed by other organizations for all domains. The difference was statistically significant for all domains with the exception of clarity of presentation (P = 0.07.The qualities of CPGs on MG were generally acceptable with several flaws. The AGREE II instrument should be adopted by guideline developers, particularly in China.

Biosorption of copper(II) and lead(II) onto potassium hydroxide treated pine cone powder.

Science.gov (United States)

Ofomaja, A E; Naidoo, E B; Modise, S J

2010-08-01

Pine cone powder surface was treated with potassium hydroxide and applied for copper(II) and lead(II) removal from solution. Isotherm experiments and desorption tests were conducted and kinetic analysis was performed with increasing temperatures. As solution pH increased, the biosorption capacity and the change in hydrogen ion concentration in solution increased. The change in hydrogen ion concentration for lead(II) biosorption was slightly higher than for copper(II) biosorption. The results revealed that ion-exchange is the main mechanism for biosorption for both metal ions. The pseudo-first order kinetic model was unable to describe the biosorption process throughout the effective biosorption period while the modified pseudo-first order kinetics gave a better fit but could not predict the experimentally observed equilibrium capacities. The pseudo-second order kinetics gave a better fit to the experimental data over the temperature range from 291 to 347 K and the equilibrium capacity increased from 15.73 to 19.22 mg g(-1) for copper(II) and from 23.74 to 26.27 for lead(II). Activation energy was higher for lead(II) (22.40 kJ mol(-1)) than for copper(II) (20.36 kJ mol(-1)). The free energy of activation was higher for lead(II) than for copper(II) and the values of DeltaH* and DeltaS* indicate that the contribution of reorientation to the activation stage is higher for lead(II) than copper(II). This implies that lead(II) biosorption is more spontaneous than copper(II) biosorption. Equilibrium studies showed that the Langmuir isotherm gave a better fit for the equilibrium data indicating monolayer coverage of the biosorbent surface. There was only a small interaction between metal ions when simultaneously biosorbed and cation competition was higher for the Cu-Pb system than for the Pb-Cu system. Desorption studies and the Dubinin-Radushkevich isotherm and energy parameter, E, also support the ion-exchange mechanism. Copyright 2010 Elsevier Ltd. All rights reserved.

Novel chelating resin with cyanoguanidine group: Useful recyclable materials for Hg(II) removal in aqueous environment

International Nuclear Information System (INIS)

Ma Xiaojie; Li Yanfeng; Ye Zhengfang; Yang Liuqing; Zhou Lincheng; Wang Liyuan

2011-01-01

A novel chelating resin containing cyanoguanidine moiety has been successfully prepared by the functionalizing reaction of a macroporous bead based on chloromethylated copolymer of styrene-divinylbenzene (CMPS) with dicyandiamide (DCDA) in the presence of phase transfer catalyst. The Fourier transform-infrared spectra (FT-IR) and scanning electron microscopy (SEM) were employed in the characterization of the resulting chelating resin, meanwhile, the adsorption properties of the resin for Hg(II) were investigated by batch and column methods. The results indicated that the resin displayed a marked advantage in Hg(II) binding capacity, and the saturated adsorption capacity estimated from the Langmuir model was dramatically up to 1077 mg g -1 at 45 deg. C. Furthermore, it was found that the resin was able to selectively separate Hg(II) from multicomponent solutions with Zn(II), Cu(II), Pb(II) and Mg(II). The desorption process of Hg(II) was tested with different eluents and the ratio of the highest recovery reached to 96% under eluting condition of 1 M HCl + 10% thiourea. Consequently, the resulting chelating resin would provide a potential application for treatment process of Hg(II) containing wastewater.

Mg Incorporation Efficiency in Pulsed MOCVD of N-Polar GaN:Mg

Science.gov (United States)

Marini, Jonathan; Mahaboob, Isra; Hogan, Kasey; Novak, Steve; Bell, L. D.; Shahedipour-Sandvik, F.

2017-10-01

We report on the effect of growth polarity and pulsed or δ -doped growth mode on impurity incorporation in metalorganic chemical vapor deposition-grown GaN. In Ga-polar orientation, up to 12× enhancement in Mg concentration for given Mg flow rate is observed, resulting in enhanced p-type conductivity for these samples. In contrast, this enhancement effect is greatly diminished for N-polar samples, falling off with increasing Mg flow and showing maximum enhancement of 2.7× at 30 nmol/min Mg flow. At higher Mg flow rates, Mg incorporation at normal levels did not correspond to p-type conductivity, which may be due to Mg incorporation at nonacceptor sites. Concentrations of C, O, and Si were also investigated, revealing dependence on Mg flow in N-polar pulsed samples. Carbon incorporation was found to decrease with increasing Mg flow, and oxygen incorporation was found to remain high across varied Mg flow. These effects combine to result in N-polar samples that are not p-type when using the pulsed growth mode.

Removal of Fe(II) from tap water by electrocoagulation technique

Energy Technology Data Exchange (ETDEWEB)

Ghosh, D.; Solanki, H. [Department of Chemical Engineering, Indian Institute of Technology, Guwahati 781039 (India); Purkait, M.K. [Department of Chemical Engineering, Indian Institute of Technology, Guwahati 781039 (India)], E-mail: mihir@iitg.ernet.in

2008-06-30

Electrocoagulation (EC) is a promising electrochemical technique for water treatment. In this work electrocoagulation (with aluminum as electrodes) was studied for iron Fe(II) removal from aqueous medium. Different concentration of Fe(II) solution in tap water was considered for the experiment. During EC process, various amorphous aluminum hydroxides complexes with high sorption capacity were formed. The removal of Fe(II) was consisted of two principal steps; (a) oxidation of Fe(II) to Fe(III) and (b) subsequent removal of Fe(III) by the freshly formed aluminum hydroxides complexes by adsorption/surface complexation followed by precipitation. Experiments were carried out with different current densities ranging from 0.01 to 0.04 A/m{sup 2}. It was observed that the removal of Fe(II) increases with current densities. Inter electrode distance was varied from 0.005 to 0.02 m and was found that least inter electrode distance is suitable in order to achieve higher Fe(II) removal. Other parameters such as conductivity, pH and salt concentration were kept constant as per tap water quality. Satisfactory iron removal of around 99.2% was obtained at the end of 35 min of operation from the initial concentration of 25 mg/L Fe(II). Iron concentration in the solution was determined using Atomic absorption spectrophotometer. By products obtained from the electrocoagulation bath were analyzed by SEM image and corresponding elemental analysis (EDAX). Cost estimation for the electrocoagulation was adopted and explained well. Up to 15 mg/L of initial Fe(II) concentration, the optimum total cost was 6.05 US$/m{sup 3}. The EC process for removing Fe(II) from tap water is expected to be adaptable for household use.

Separation study of Mg+2 from seawater and RO brine through a facilitated bulk liquid membrane transport using 18-Crown-6

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Mir Mahdi Zahedi

2017-12-01

Full Text Available A facilitated bulk liquid membrane transport approach is studied for Mg(II extraction from seawater and reversed osmosis brine simulated media using 18-Crown-6 and dibenzo (DB-18-Crown-6. The work is based on investigating the experimental parameters affecting the transport efficiency, such as pH of feed and receiving phase, type of membrane solvent, temperature, type and concentration of the carrier, and stripping solution conditions. The transported amount of magnesium ions from feed phase (Mg(II = 0.059 M, NaCl = 0.01 M, pH = 3.3 across a chloroform membrane (18C6 = 0.001 M into the receiving phase (SCN− 0.1 M pH 3 was found to be %97 (±0.7 after 2.5 hr. The selectivity of the method was evaluated by performing competitive transport experiments on the mixtures containing Ca2+, Na+, K+, and Mg2+ ions.

Analysis of an M/G/1 queue with customer impatience and an adaptive arrival process

NARCIS (Netherlands)

Boxma, O.J.; Prabhu, B.J.

2009-01-01

We study an M/G/1 queue with impatience and an adaptive arrival process. The rate of the arrival process changes according to whether an incoming customer is accepted or rejected. We analyse two different models for impatience : (i) based on workload, and (ii) based on queue length. For the

Advanced oxidation removal of hypophosphite by O3/H2O2 combined with sequential Fe(II) catalytic process.

Science.gov (United States)

Zhao, Zilong; Dong, Wenyi; Wang, Hongjie; Chen, Guanhan; Wang, Wei; Liu, Zekun; Gao, Yaguang; Zhou, Beili

2017-08-01

Elimination of hypophosphite (HP) was studied as an example of nickel plating effluents treatment by O 3 /H 2 O 2 and sequential Fe(II) catalytic oxidation process. Performance assessment performed with artificial HP solution by varying initial pH and employing various oxidation processes clearly showed that the O 3 /H 2 O 2 ─Fe(II) two-step oxidation process possessed the highest removal efficiency when operating under the same conditions. The effects of O 3 dosing, H 2 O 2 concentration, Fe(II) addition and Fe(II) feeding time on the removal efficiency of HP were further evaluated in terms of apparent kinetic rate constant. Under improved conditions (initial HP concentration of 50 mg L -1 , 75 mg L -1 O 3 , 1 mL L -1 H 2 O 2 , 150 mg L -1 Fe(II) and pH 7.0), standard discharge (<0.5 mg L -1 in China) could be achieved, and the Fe(II) feeding time was found to be the limiting factor for the evolution of apparent kinetic rate constant in the second stage. Characterization studies showed that neutralization process after oxidation treatment favored the improvement of phosphorus removal due to the formation of more metal hydroxides. Moreover, as a comparison with lab-scale Fenton approach, the O 3 /H 2 O 2 ─Fe(II) oxidation process had more competitive advantages with respect to applicable pH range, removal efficiency, sludge production as well as economic costs. Copyright © 2017 Elsevier Ltd. All rights reserved.

Stabilization of arsenic and lead by magnesium oxide (MgO) in different seawater concentrations.

Science.gov (United States)

Kameda, Kentaro; Hashimoto, Yohey; Ok, Yong Sik

2018-02-01

Ongoing sea level rise will have a major impact on mobility and migration of contaminants by changing a number of natural phenomena that alter geochemistry and hydrology of subsurface environment. In-situ immobilization techniques may be a promising remediation strategy for mitigating contaminant mobility induced by sea level rise. This study investigated the reaction mechanisms of magnesium oxide (MgO) with aqueous Pb and As under freshwater and seawater using XAFS spectroscopy. Initial concentrations of Pb and As in freshwater strongly controlled the characteristics of the reaction product of MgO. Our study revealed that i) the removal of aqueous Pb and As by MgO was increased by the elevation of seawater concentration, and ii) the removal of As was attributed primarily to (inner-sphere) surface adsorption on MgO, independent on seawater concentrations, and iii) the retention mechanism of Pb was dependent on seawater concentrations where formations of Pb oxides and adsorption on the MgO surface were predominant in solutions with low and high salinity, respectively. The release of As fixed with MgO significantly increased in seawater compared to freshwater, although the amount of As desorbed accounted for <0.2% of total As. Copyright © 2017 Elsevier Ltd. All rights reserved.

Crystal structure of the high-affinity Na+,K+-ATPase–ouabain complex with Mg2+ bound in the cation binding site

DEFF Research Database (Denmark)

Laursen, Mette; Yatime, Laure; Nissen, Poul

2013-01-01

of ouabain and the side chains of αM1, αM2, and αM6. Furthermore, the structure reveals that cation transport site II is occupied by Mg2+, and crystallographic studies indicate that Rb+ and Mn2+, but not Na+, bind to this site. Comparison with the low-affinity [K2]E2–MgFx–ouabain structure [Ogawa et al...

Intra-individual comparison of different contrast media concentrations (300 mg, 370 mg and 400 mg iodine) in MDCT

Energy Technology Data Exchange (ETDEWEB)

Behrendt, Florian F.; Keil, Sebastian; Plumhans, Cedric; Guenther, Rolf W. [RWTH Aachen University, Department of Diagnostic Radiology, University Hospital, Aachen (Germany); Pietsch, Hubertus; Jost, Gregor; Sieber, Martin A.; Seidensticker, Peter [Bayer Schering Pharma AG, Berlin (Germany); Mahnken, Andreas H. [RWTH Aachen University, Department of Diagnostic Radiology, University Hospital, Aachen (Germany); RWTH Aachen University, Applied Medical Engineering, Helmholtz-Institute for Biomedical Engineering, Aachen (Germany)

2010-07-15

To compare intra-individual contrast enhancement in multi-detector-row computed tomography (MDCT) using contrast media (CM) containing 300, 370 and 400 mg iodine per ml (mgI/ml). Six pigs underwent repeated chest MDCT using three different CM (iopromide 300, iopromide 370, iomeprol 400). An identical iodine delivery (IDR) rate of 1.5 gI/s and a constant total iodine dose of 300 mg/kg body weight were used. Dynamic CT were acquired at the level of the pulmonary artery, and the ascending and descending aorta. After the time enhancement curves were computed, the pulmonary and aortic peak enhancement, time to peak and plateau time above 300 HU were calculated. Intra-individual peak contrast enhancement was significantly higher for the 300 mgI/ml contrast medium compared with the 370 and 400 mgI/ml media: pulmonary trunk 595 HU vs 516 HU (p = 0.0093) vs 472HU (p = 0.0005), and aorta 505 HU vs 454 HU (p = 0.0008) vs 439 HU (p = 0.0001), respectively. Comparison of time to peaks showed no significant difference. Plateau times were significantly longer for the 300 mgI/ml than for the 370 and 400 mgI/ml CM at all anatomical sites. Given normalised IDR and total iodine burden, the use of CM with a standard concentration with 300 mg iodine/ml provides improved contrast enhancement compared with highly concentrated CM in the chest. (orig.)

Kinetic and isotherm modeling of Cd (II) adsorption by L-cysteine functionalized multi-walled carbon nanotubes as adsorbent.

Science.gov (United States)

Taghavi, Mahmoud; Zazouli, Mohammad Ali; Yousefi, Zabihollah; Akbari-adergani, Behrouz

2015-11-01

In this study, multi-walled carbon nanotubes were functionalized by L-cysteine to show the kinetic and isotherm modeling of Cd (II) ions onto L-cysteine functionalized multi-walled carbon nanotubes. The adsorption behavior of Cd (II) ion was studied by varying parameters including dose of L-MWCNTs, contact time, and cadmium concentration. Equilibrium adsorption isotherms and kinetics were also investigated based on Cd (II) adsorption tests. The results showed that an increase in contact time and adsorbent dosage resulted in increase of the adsorption rate. The optimum condition of the Cd (II) removal process was found at pH=7.0, 15 mg/L L-MWCNTs dosage, 6 mg/L cadmium concentration, and contact time of 60 min. The removal percent was equal to 89.56 at optimum condition. Langmuir and Freundlich models were employed to analyze the experimental data. The data showed well fitting with the Langmuir model (R2=0.994) with q max of 43.47 mg/g. Analyzing the kinetic data by the pseudo-first-order and pseudo-second-order equations revealed that the adsorption of cadmium using L-MWSNTs following the pseudo-second-order kinetic model with correlation coefficients (R2) equals to 0.998, 0.992, and 0.998 for 3, 6, and 9 mg/L Cd (II) concentrations, respectively. The experimental data fitted very well with the pseudo-second-order. Overall, treatment of polluted solution to Cd (II) by adsorption process using L-MWCNT can be considered as an effective technology.

LABORATORY REPORT ON THE REDUCTION AND STABILIZATION (IMMOBILIZATION) OF PERTECHNETATE TO TECHNETIUM DIOXIDE USING TIN(II)APATITE

Energy Technology Data Exchange (ETDEWEB)

DUNCAN JB; HAGERTY K; MOORE WP; RHODES RN; JOHNSON JM; MOORE RC

2012-06-01

This effort is part of the technetium management initiative and provides data for the handling and disposition of technetium. To that end, the objective of this effort was to challenge tin(II)apatite (Sn(II)apatite) against double-shell tank 241-AN-105 simulant spiked with pertechnetate (TcO{sub 4}{sup -}). The Sn(II)apatite used in this effort was synthesized on site using a recipe developed at and provided by Sandia National Laboratories; the synthesis provides a high quality product while requiring minimal laboratory effort. The Sn(II)apatite reduces pertechnetate from the mobile +7 oxidation state to the non-mobile +4 oxidation state. It also sequesters the technetium and does not allow for re-oxidization to the mo bile +7 state under acidic or oxygenated conditions within the tested period oftime (6 weeks). Previous work (RPP-RPT-39195, Assessment of Technetium Leachability in Cement-Stabilized Basin 43 Groundwater Brine) indicated that the Sn(II)apatite can achieve an ANSI leachability index in Cast Stone of 12.8. The technetium distribution coefficient for Sn(II)apatite exhibits a direct correlation with the pH of the contaminated media. Table A shows Sn(II)apatite distribution coefficients as a function of pH. The asterisked numbers indicate that the lower detection limit of the analytical instrument was used to calculate the distribution coefficient as the concentration of technetium left in solution was less than the detection limit. The loaded sample (200 mg of Sn(II)apatite loaded with O.311 mg of Tc-99) was subjected to different molarities of nitric acid to determine if the Sn(II)apatite would release the sequestered technetium. The acid was allowed to contact for 1 minute with gentle shaking ('1st wash'); the aqueous solution was then filtered, and the filtrate was analyzed for Tc-99. Table B shows the results ofthe nitric acid exposure. Another portion of acid was added, shaken for a minute, and filtered ('2nd wash'). The

Quasicrystal-reinforced Mg alloys.

Science.gov (United States)

Kyun Kim, Young; Tae Kim, Won; Hyang Kim, Do

2014-04-01

The formation of the icosahedral phase (I-phase) as a secondary solidification phase in Mg-Zn-Y and Mg-Zn-Al base systems provides useful advantages in designing high performance wrought magnesium alloys. The strengthening in two-phase composites (I-phase + α -Mg) can be explained by dispersion hardening due to the presence of I-phase particles and by the strong bonding property at the I-phase/matrix interface. The presence of an additional secondary solidification phase can further enhance formability and mechanical properties. In Mg-Zn-Y alloys, the co-presence of I and Ca 2 Mg 6 Zn 3 phases by addition of Ca can significantly enhance formability, while in Mg-Zn-Al alloys, the co-presence of the I-phase and Mg 2 Sn phase leads to the enhancement of mechanical properties. Dynamic and static recrystallization are significantly accelerated by addition of Ca in Mg-Zn-Y alloy, resulting in much smaller grain size and more random texture. The high strength of Mg-Zn-Al-Sn alloys is attributed to the presence of finely distributed Mg 2 Sn and I-phase particles embedded in the α -Mg matrix.

Effect of Dunaliella tertiolecta organic exudates on the Fe(II) oxidation kinetics in seawater.

Science.gov (United States)

González, A G; Santana-Casiano, J M; González-Dávila, M; Pérez-Almeida, N; Suárez de Tangil, M

2014-07-15

The role played by the natural organic ligands excreted by the green algae Dunaliella tertiolecta on the Fe(II) oxidation rate constants was studied at different stages of growth. The concentration of dissolved organic carbon increased from 2.1 to 7.1 mg L(-1) over time of culture. The oxidation kinetics of Fe(II) was studied at nanomolar levels and under different physicochemical conditions of pH (7.2-8.2), temperature (5-35 °C), salinity (10-37), and dissolved organic carbon produced by cells (2.1-7.1 mg L(-1)). The experimental rate always decreased in the presence of organic exudates with respect to that in the control seawater. The Fe(II) oxidation rate constant was also studied in the context of Marcus theory, where ΔG° was 39.31-51.48 kJ mol(-1). A kinetic modeling approach was applied for computing the equilibrium and rate constants for Fe(II) and exudates present in solution, the Fe(II) speciation, and the contribution of each Fe(II) species to the overall oxidation rate constant. The best fit model took into account two acidity equilibrium constants for the Fe(II) complexing ligands with pKa,1=9.45 and pKa,2=4.9. The Fe(II) complexing constants were KFe(II)-LH=3×10(10) and KFe(II)-L=10(7), and the corresponding computed oxidation rates were 68±2 and 36±8 M(-1) min(-1), respectively.

Safety and toxicological evaluation of a novel, water-soluble undenatured type II collagen.

Science.gov (United States)

Yoshinari, Orie; Marone, Palma Ann; Moriyama, Hiroyoshi; Bagchi, Manashi; Shiojima, Yoshiaki

2013-09-01

This study was conducted to determine the broad-spectrum safety of a novel, water-soluble undenatured type II collagen (NEXT-II) derived from chicken sternum cartilage. The presence of epitope in NEXT-II was confirmed by using a commercial kit. The acute oral LD₅₀ of NEXT-II was found to be greater than 5000 mg/kg bw in rats, while the single-dose acute dermal LD₅₀ was greater than 2000 mg/kg bw. The primary dermal irritation index (PDII) of NEXT-II was found to be 1.8 and classified as slightly irritating to the skin. In primary eye irritation studies, the maximum mean total score (MMTS) of NEXT-II was observed to be 7.3 and classified as minimally irritating to the eye. Long-term safety studies were conducted in dogs over a period of 150 d, and no significant changes were observed in body weight, heart rate, respiration rate and blood chemistry. NEXT-II does not induce mutagenicity in the bacterial reverse mutation test in five Salmonella typhimurium strains either with or without metabolic activation. Furthermore, two experiments were conducted to assess the potential of NEXT-II to induce mutations with and without metabolic activation at the mouse lymphoma thymidine kinase locus using the cell line L5178Y. No biologically relevant increase of mutants was observed. Also, no dose-dependent toxicity was observed. Furthermore, colony sizing showed no clastogenic effects induced by NEXT-II under the experimental conditions. These studies demonstrated the broad spectrum of safety of NEXT-II.

Hydriding and dehydriding rates of Mg, Mg-10TaF5, and Mg-10NbF5 prepared via reactive mechanical grinding

Science.gov (United States)

Song, Myoung Youp; Kwak, Young Jun; Lee, Seong Ho; Park, Hye Ryoung

2015-01-01

In this work, TaF5 and NbF5 were chosen as additives to enhance the hydriding and dehydriding rates of Mg. Mg, Mg-10TaF5, and Mg-10NbF5 samples were prepared by reactive mechanical grinding. The hydriding and dehydriding properties of the samples were then examined. Mg-10TaF5 had the largest amount of hydrogen absorbed for 30 min and the highest initial dehydriding rate after incubation period, followed in order by Mg-10NbF5, and Mg. At 593 K under 12 bar H2 at the first cycle, Mg-10TaF5 absorbed 3.63 wt% H for 5 min and 4.53 wt% H for 30 min. At 593 K under 1.0 bar H2 at the first cycle, Mg-10TaF5 desorbed 0 wt% H for 2.5 min, 0.59 wt% H for 5 min, 3.42 wt% H for 30 min, and 4.24 wt% H for 60 min. The reactive mechanical grinding of Mg with TaF5 or NbF5 is believed to have facilitated the nucleation and to have decreased the diffusion distances of hydrogen atoms. These two effects are believed to have increased the hydriding and dehydriding rates of Mg. The MgF2 and Ta2H formed in Mg-10TaF5, and the MgF2, NbH2, and NbF3 formed in Mg-10NbF5 are considered to have enhanced both of these effects.

Evaluating Production of Cyclopentyl Tetraethers by Marine Group II Euryarchaeota in the Pearl River Estuary and Coastal South China Sea: Potential Impact on the TEX86 Paleothermometer

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Jin-Xiang Wang

2017-10-01

Full Text Available TEX86 [TetraEther indeX of glycerol dialkyl glycerol tetraethers (GDGTs with 86 carbon atoms] has been widely applied to reconstruct (paleo- sea surface temperature. Marine Group I (MG-I Thaumarchaeota were thought to be the primary source of GDGTs constituting the TEX86 formula; however, recent research has suggested that Marine Group II (MG-II Euryarchaeota may also contribute significantly to the GDGT pool in the ocean. Little is known regarding the potential impact of MG-II Euryarchaeota-derived GDGTs on TEX86 values recorded in marine sediments. In this study, we assessed the relationship between distributions of GDGTs and MG-II Euryarchaeota and evaluated its potential effect on the TEX86 proxy. Lipid and DNA analyses were performed on suspended particulate matter and surface sediments collected along a salinity gradient from the lower Pearl River (river water and its estuary (mixing water to the coastal South China Sea (SCS, seawater. TEX86-derived temperatures from the water column and surface sediments were significantly correlated and both were lower than satellite-based temperatures. The ring index (RI values in these environments were higher than predicted from the calculated TEX86-RI correlation, indicating that the GDGT pool in the water column of the PR estuary and coastal SCS comprises relatively more cyclopentane rings, which thereby altered TEX86 values. Furthermore, the abundance of MG-II Euryarchaeota 16S rRNA gene in the mixing water was two to three orders of magnitude higher than those observed in the river or seawater. Significant linear correlations were observed between the gene abundance ratio of MG-II Euryarchaeota to total archaea and the fractional abundance of GDGTs with cyclopentane rings. Collectively, these results suggest that MG-II Euryarchaeota likely produce a large proportion of GDGTs with 1–4 cyclopentane moieties, which may bias TEX86 values in the water column and sediments. As such, valid

Selective sensing of mercury(II) using PVC-based membranes incorporating recently synthesized 1,3-alternate thiacalix[4]crown ionophore.

Science.gov (United States)

Mahajan, Rakesh Kumar; Kamal, Ajar; Kumar, Naresh; Bhalla, Vandana; Kumar, Manoj

2013-05-01

The construction and electrodes characteristics of poly(vinylchloride) (PVC)-based polymeric membrane electrode (PME) and coated graphite electrode (CGE), incorporating 1,3-alternate thiacalix[4]crown as ionophore for estimation of Hg(II) ions, are reported here. The best potential response was observed for PME-1 having membrane composition of: ionophore (6.2 mg), PVC (100.0 mg), 2-nitrophenyl octyl ether (2-NPOE; 200.0 mg), and sodium tetraphenyl borate (NaTPB; 2.0 mg); for CGE-1 with the membrane composition: ionophore (3.5 mg), PVC (40.0 mg), 2-NPOE (80.0 mg), and NaTPB (2.0 mg). The electrodes exhibits Nernstian slope of 29.16 mV/decade with PME-1 and 30.39 mV/decade with CGE-1 for Hg(II) ions over wide concentration range, i.e., 1.0 × 10(-1) to 5.0 × 10(-6) M with PME-1 and 1.0 × 10(-1) to 5.0 × 10(-7) M with CGE-1. Lower detection limits were found to be 9.77 × 10(-6) M for PME-1 and 7.76 × 10(-7) M for CGE-1 with response time varying from 10 to 20 s. Also, these electrodes work within pH range of 2.0-6.0 for PME-1 and 1.5-6.5 for CGE-1. Overall, CGE-1 has been found to be better than PME-1. CGE-1 has been used as indicator electrode for the potentiometric titration of Hg(II) ions with EDTA as well as successfully applied for determination of Hg(II) content in wastewater, insecticide, dental amalgam, and ayurvedic medicines samples with very good performance (0.9974 correlation coefficient in the comparison against volumetric method).

Superconducting properties of MgB2 particle impregnated with Mg-based alloys

International Nuclear Information System (INIS)

Shimizu, Yusuke; Matsuda, Kenji; Mizutani, Manabu; Nishimura, Katsuhiko; Kawabata, Tokimasa; Ikeno, Susumu; Hishinuma, Yoshimitsu; Aoyama, Shigeki

2011-01-01

The three-dimensional penetration method combined with semi-solid casting (SS-3DPC) was utilized to prepare magnesium diboride (MgB 2 ) powder composite materials with various host materials of Mg, Mg-3%Al, Mg-3%Al-1%Zn, Mg-9%Al, and Mg-9%Al-1%Zn. X-ray diffraction measurements indicated predominant peak patterns of MgB 2 and a host alloy, implying that the host material tightly bonded MgB 2 grains without melting the MgB 2 powder. This was confirmed by SEM images. Measured electrical resistivity and magnetization versus temperature showed clear signals of superconducting transition temperature of 27-38 K for all the samples cut out from the billets. Magnetic hysteresis loop observed at 5 K enabled us to estimate a critical current density (J c ) based on the extended Bean model. Additions of aluminum and zinc elements to magnesium host-matrix were found to enhance J c and increase residual resistivity (ρ 0 ) suggesting that aluminum and zinc have an effect on pinning magnetic flux flow for J c enhancement, and scattering conduction electrons for increase of ρ 0 . (author)

Optical absorption and thermoluminescence in Mg O, Mg O:Ni and Mg O:Li irradiated at room temperature

International Nuclear Information System (INIS)

Delgado, L.

1984-01-01

Optical absorption and thermoluminescence (TL) studies in Mg O, Mg O:Ni and Mg O:Li irradiated at room temperature are presented. In pure Mg O the thermal annihilation of Fe3+ by recombination with thermally released electrons at ∼ 90 and 175 degree centigree and the V center annealing by hole release up to 100 degree centigree cause the observed glow peaks at these temperatures. The TL excitation spectrum shows two maxima at 245 nm (electron center) and 288 nm (Fe3+). In Mg O:Ni X irradiation induces Fe 2 + →- Fe 3 + and Ni 2 + → Ni 3 + oxidations. Two TL emission bands centered at 110 degree centigree (red) and 80 o C (green) are assigned to electron release and their recombination at Fe 3 + and Ni 3 + respectively. In Mg O:Li two TL emission bands, one blue (430 nm) and the other red (730 nm) with excitation maxima at 245 nm (electron center) and 200 nm (hole center) respectively are observed. No V-center formation was detected in both Ni and Li doped samples. (Author) 42 refs

Cd(II) removal and recovery enhancement by using acrylamide–titanium nanocomposite as an adsorbent

Energy Technology Data Exchange (ETDEWEB)

Sharma, Ajit; Lee, Byeong-Kyu, E-mail: bklee@ulsan.ac.kr

2014-09-15

Graphical abstract: - Highlights: • Acrylamide doping initiated 10–20% increase in the particle size. • R-NH{sub 2}Cd{sup 2+} and Cd-O onto the nanocomposite improved Cd(II) adsorption. • Coexisting cations did not make any significant interference of Cd(II) removal. • Increased Ti nanoparticles leads to decrease in mass swelling of acrylamide. - Abstract: Acrylamide (AM) was in-situ doped into titanium during sol–gel reaction and used as an adsorbent for cadmium removal from aqueous solution. The resulting TiO{sub 2}-AM nanocomposite was characterized by particle size distribution (PSD) and thermogravimetric analysis (TGA). After cadmium adsorption, the nanocomposite was also characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy/energy-dispersive X-ray (SEM/EDX) and X-ray photoelectron spectroscopy (XPS) analyses. The adsorption behavior of the nanocomposite was examined by kinetic and equilibrium studies in batch conditions. The maximum cadmium binding capacity of TiO{sub 2}-AM was 322.58 mg g{sup −1} at an optimum pH of 8.0, compared to 86.95 mg g{sup −1} for nano-titanium. Cadmium sorption showed pseudo-second-order kinetics with a rate constant of 4.0 × 10{sup −4} and 9.4 × 10{sup −5} g mg{sup −1} min{sup −1} at an initial Cd(II) concentration of 100 and 500 mg L{sup −1}, respectively. Cd (II) adsorption interference of cations (Pb{sup 2+}, Cu{sup 2+}, Co{sup 2+} and Zn{sup +2}) and anions (Cl{sup −}, SO{sub 4}{sup 2−}, CO{sub 3}{sup 2−}) at pH 8 was very nominal because of favorable complex formation of Cd(II) and amide. The Cd(II) adsorption of 27% that was achieved in the fifth cycle was regenerated with 0.05 N acidic solutions.

Understanding corrosion via corrosion product characterization: II. Role of alloying elements in improving the corrosion resistance of Zn-Al-Mg coatings on steel

International Nuclear Information System (INIS)

Volovitch, P.; Vu, T.N.; Allely, C.; Abdel Aal, A.; Ogle, K.

2011-01-01

Highlights: → Origins of better corrosion resistance of ZnAlMg coatings than galvanized steel. → Comparative study of corrosion products formed on ZnAlMg, ZnMg and Zn coatings. → Modeling of dissolution and precipitation stages of corrosion. → At early stages Mg stabilizes protective zinc basic salts during dry-wet cycling. → At later stages Al dissolves at high pH forming protective layered double hydroxides. - Abstract: Corrosion products are identified on Zn, ZnMg and ZnAlMg coatings in cyclic corrosion tests with NaCl or Na 2 SO 4 containing atmospheres. For Mg-containing alloys the improved corrosion resistance is achieved by stabilization of protective simonkolleite and zinc hydroxysulfate. At later stages, the formation of layered double hydroxides (LDH) is observed for ZnAlMg. According to thermodynamic modeling, Mg 2+ ions bind the excess of carbonate or sulfate anions preventing the formation of soluble or less-protective products. A preferential dissolution of Zn and Mg at initial stages of corrosion is confirmed by in situ dissolution measurement. The physicochemical properties of different corrosion products are compared.

Synthesis of nanocrystalline TiB2 powder from TiO2, B2O3 and Mg ...

Indian Academy of Sciences (India)

gered by using: (i) a furnace or (ii) an electrical element touching the surface ... plicity, low energy consumption and good purity of the products. [12,13]. SHS method .... Similar to the TiO2–Mg system, by increasing the ini- tial temperature, the ...

Selective solid-phase extraction of Hg(II) using silica gel surface - imprinting technique

International Nuclear Information System (INIS)

Zheng, H.; Geng, T.; Hu, L.

2008-01-01

A new ion-imprinted amino-functionalized silica gel sorbent was synthesized by surface-imprinting technique for preconcentration and separation of Hg(II) prior to its determination by inductively coupled plasma optical emission spectrometry (ICP-OES). Compared to the traditional solid sorbents and non-imprinted polymer particles, the ion-imprinted polymers (IIPs) have higher adsorption capacity and selectivity for Hg(II). The maximum static adsorption capacity of the imprinted and non-imprinted sorbent for Hg(II) was 29.89 mg g -1 and 11.21 mg g -1 , respectively. The highest selectivity coefficient for Hg(II) in the presence of Zn(II) exceeded 230. The detection limit (3σ) of the method was 0.25 μg L -1 . The relative standard deviation of the method was 2.5% for eight replicate determinations of 10 μg of Hg 2+ in 200 mL-in-volume water sample. The procedure was validated by performing the analysis of the certified river sediment sample (GBW 08603, China) using the standard addition method. The developed method was also successfully applied to the determination of trace mercury in Chinese traditional medicine and water samples with satisfactory results. (authors)

The Influence of MgH2 on the Assessment of Electrochemical Data to Predict the Degradation Rate of Mg and Mg Alloys

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Wolf-Dieter Mueller

2014-06-01

Full Text Available Mg and Mg alloys are becoming more and more of interest for several applications. In the case of biomaterial applications, a special interest exists due to the fact that a predictable degradation should be given. Various investigations were made to characterize and predict the corrosion behavior in vitro and in vivo. Mostly, the simple oxidation of Mg to Mg2+ ions connected with adequate hydrogen development is assumed, and the negative difference effect (NDE is attributed to various mechanisms and electrochemical results. The aim of this paper is to compare the different views on the corrosion pathway of Mg or Mg alloys and to present a neglected pathway based on thermodynamic data as a guideline for possible reactions combined with experimental observations of a delay of visible hydrogen evolution during cyclic voltammetry. Various reaction pathways are considered and discussed to explain these results, like the stability of the Mg+ intermediate state, the stability of MgH2 and the role of hydrogen overpotential. Finally, the impact of MgH2 formation is shown as an appropriate base for the prediction of the degradation behavior and calculation of the corrosion rate of Mg and Mg alloys.

Structural characteristics and corrosion behavior of biodegradable Mg-Zn, Mg-Zn-Gd alloys.

Science.gov (United States)

Kubásek, J; Vojtěch, D

2013-07-01

In this research, binary Mg-Zn (up to 3 wt% Zn) and ternary Mg-Zn-Gd (up to 3 wt% Gd, 3 wt% Zn) alloys were prepared by induction melting in an argon atmosphere. The structures of these alloys were characterized using light and scanning electron microscopy, energy dispersive spectrometry, X-ray diffraction and X-ray fluorescence. In addition, Brinell hardness measurements were taken to supplement these studies. Corrosion behavior was evaluated by immersion tests and potentiodynamic measurements in a physiological solution (9 g/l NaCl). Depending on the composition, structures of the as-cast alloys contained α-Mg dendrites, MgZn, Mg5Gd and Mg3Gd2Zn3 phases. Compared to pure Mg, zinc improved the corrosion resistance of binary Mg-Zn. Gadolinium also improved the corrosion resistance in the case of Mg-1Zn-3Gd alloy. The highest corrosion rate was observed for Mg-3Zn-3Gd alloy. Our results improve the understanding of the relationships between the structure and corrosion behavior of our studied alloy systems.

Coherent interface structures and intergrain Josephson coupling in dense MgO/Mg{sub 2}Si/MgB{sub 2} nanocomposites

Energy Technology Data Exchange (ETDEWEB)

Ueno, Katsuya; Takahashi, Kazuyuki; Uchino, Takashi, E-mail: uchino@kobe-u.ac.jp [Department of Chemistry, Graduate School of Science, Kobe University, Nada, Kobe 657-8501 (Japan); Nagashima, Yukihito [Nippon Sheet Glass Co., Ltd., Konoike, Itami 664-8520 (Japan); Seto, Yusuke [Department of Planetology, Graduate School of Science, Kobe University, Nada, Kobe 657-8501 (Japan); Matsumoto, Megumi; Sakurai, Takahiro [Center for Support to Research and Education Activities, Kobe University, Nada, Kobe 657-8501 (Japan); Ohta, Hitoshi [Molecular Photoscience Research Center, Kobe University, Nada, Kobe 657-8501 (Japan)

2016-07-07

Many efforts are under way to control the structure of heterointerfaces in nanostructured composite materials for designing functionality and engineering application. However, the fabrication of high-quality heterointerfaces is challenging because the crystal/crystal interface is usually the most defective part of the nanocomposite materials. In this work, we show that fully dense insulator (MgO)/semiconductor(Mg{sub 2}Si)/superconductor(MgB{sub 2}) nanocomposites with atomically smooth and continuous interfaces, including epitaxial-like MgO/Mg{sub 2}Si interfaces, are obtained by solid phase reaction between metallic magnesium and a borosilicate glass. The resulting nanocomposites exhibit a semiconductor-superconducting transition at 36 K owing to the MgB{sub 2} nanograins surrounded by the MgO/Mg{sub 2}Si matrix. This transition is followed by the intergrain phase-lock transition at ∼24 K due to the construction of Josephson-coupled network, eventually leading to a near-zero resistance state at 17 K. The method not only provides a simple process to fabricate dense nanocomposites with high-quality interfaces, but also enables to investigate the electric and magnetic properties of embedded superconducting nanograins with good intergrain coupling.

Supercritical CO₂assisted extraction and LC-MS identification of picroside I and picroside II from Picrorhiza kurroa.

Science.gov (United States)

Patil, Ajit A; Sachin, Bhusari S; Shinde, Devanand B; Wakte, Pravin S

2013-02-01

Picroside I and picroside II have been studied intensively because of their pharmacological actions and clinical applications. Numerous methods have been reported for extracting picroside I and picroside II from Picrorrhiza. kurroa rhizomes. This is the first report of picroside I and picroside II extraction using the supercritical carbon dioxide assisted extraction technique. To develop supercritical carbon dioxide assisted extraction and LC-MS identification of picroside I and picroside II from the Picrorrhiza kurroa Royle rhizomes. Surface response methodology based on 3³ fractional factorial design was used to extract picroside I and picroside II from P. kurroa rhizomes. The effects of various process factors, namely temperature (40-80°C), pressure (25-35 MPa) and co-solvent (methanol) concentration (0-10% v/v) on extraction yield of the two compounds were evaluated. The picroside I and picroside II contents were determined using validated LC-MS methodology. The maximum yield of picroside I (32.502 ± 1.131 mg/g) and picroside II (9.717 ± 0.382 mg/g) was obtained at the 10% v/v co-solvent concentration, 40°C temperature and 30 MPa pressure. The conventional Soxhlet assisted methanol extract of P. kurroa powder resulted in 36.743 ± 1.75 and 11.251 ± 0.54 mg/g yield of picroside I and picroside II, respectively. Variation of concentration and extraction time showed a significant effect on the picroside I and picroside II yield. Supercritical carbon dioxide assisted extraction using methanol as a co-solvent is an efficient and environmentally sustainable method for extracting picroside I and picroside II from P. kurroa rhizomes. Copyright © 2012 John Wiley & Sons, Ltd.

Isostructural and heterostructural MgZnO and CdZnO alloys

Energy Technology Data Exchange (ETDEWEB)

Schleife, Andre; Roedl, Claudia; Bechstedt, Friedhelm [Institut fuer Festkoerpertheorie und -optik and European Theoretical Spectroscopy Facility, Friedrich-Schiller-Universitaet Jena, 07743 Jena (Germany)

2011-07-01

One important goal of materials design is to purposefully tailor the fundamental band gap. Recently, group-II oxides such as MgO, ZnO, and CdO are discussed to possibly supersede the nitrides for certain applications, e.g. in optoelectronics. Since the band gaps of the oxides cover a large spectral range from 1.8 eV (CdO) up to 7.7 eV (MgO), their alloys seem to be promising - unless the different equilibrium crystal structures of the end components (rocksalt-MgO and -CdO vs. wurtzite-ZnO) prevent their application. By employing three different cluster statistics within a cluster-expansion approach we investigate the impact of different growth conditions on the composition of isostructural and heterostructural Mg{sub x}Zn{sub 1-x}O and Cd{sub x}Zn{sub 1-x}O alloys. Our total-energy calculations are based on density-functional theory using a generalized-gradient approximation for exchange and correlation. We also compute quasiparticle energies using the HSE03+G{sub 0}W{sub 0} approach. This allows us to derive the bowings of fundamental band gaps, which reveal a strongly nonlinear behavior. Using the solution of the Bethe-Salpeter equation for the optical polarization function we investigate the influence of the preparation conditions on the peaks related to bound excitonic states at the absorption edge.

Statin Treatment in Hypercholesterolemic Men Does Not Attenuate Angiotensin II-Induced Venoconstriction

Science.gov (United States)

Schindler, Christoph; Guenther, Kristina; Hermann, Cosima; Ferrario, Carlos M.; Schroeder, Christoph; Haufe, Sven

2014-01-01

Experimental studies suggested that statins attenuate vascular AT1 receptor responsiveness. Moreover, the augmented excessive pressor response to systemic angiotensin II infusions in hypercholesterolemic patients was normalized with statin treatment. In 12 hypercholesterolemic patients, we tested the hypothesis that statin treatment attenuates angiotensin II-mediated vasoconstriction in hand veins assessed by a linear variable differential transducer. Subjects ingested daily doses of either atorvastatin (40 mg) or positive control irbesartan (150 mg) for 30 days in a randomized and cross-over fashion. Ang II–induced venoconstriction at minute 4 averaged 59%±10% before and 28%±9% after irbesartan (mean ± SEM; Pblood pressure buffering reflexes. Trial Registration ClinicalTrials.gov NCT00154024 PMID:25264877

The role of Mg in the crystallization of monohydrocalcite

Science.gov (United States)

Rodriguez-Blanco, Juan Diego; Shaw, Samuel; Bots, Pieter; Roncal-Herrero, Teresa; Benning, Liane G.

2014-02-01

behavior should be expected for monohydrocalcite. The saturation indexes calculated for monohydrocalcite using the available solubility products from Hull and Turnbull (1973) and Kralj and Brečević (1995) are negative and show a difference of ˜0.55 (Fig. 8). We suggest that may be due to difference in the Mg contents of the monohydrocalcites used in their respective studies. This hypothesis is supported by the recent findings of Nishiyama et al. (2013), who reported that the solubility of synthetic monohydrocalcite increases with higher Mg/Ca ratios in the solid. They showed that the Ksp of monohydrocalcite can reach maximum values of Ksp = 10-6.77, which is almost one order of magnitude higher than the value of Hull and Turnbull (1973). Furthermore, Nishiyama et al. (2013) also reported an decrease in monohydrocalcite crystallite size (broadening of Bragg peaks in PXRD) with increasing solid Mg/Ca ratios, which again support our interpretation of the transition from high- to low-Mg monohydrocalcite.Although an in-depth study of the structural changes in monohydrocalcite as a function of Mg content are outside of the scope of this study, the changes in unit cell parameters during crystallization (Fig. 6) may be better understood when the χMgCO3 of the monohydrocalcite is taken into account. Regardless of Mg content, the unit cell volume remained virtually constant during stages II-III and only decreased slightly during stage IV (ΔV ≈ -0.2 Å3), in parallel with the decrease in monohydrocalcite χMgCO3. This small decrease in volume is a consequence of a mirrored change in a-axis and c-axis dimensions, which may be explained by the change in the monohydrocalcite internal structure during the loss of Mg and the transition from the high to low-Mg type (stage III to IV). The structure of monohydrocalcite is less dense and more open than calcite or aragonite (Effenberger, 1981; Neumann and Epple, 2007; Swainson, 2008), therefore it may more easily adapt to a changing Mg

Biosorption kinetics of Cd (II, Cr (III and Pb (II in aqueous solutions by olive stone

Directory of Open Access Journals (Sweden)

M. Calero

2009-06-01

Full Text Available A by-product from olive oil production, olive stone, was investigated for the removal of Cd (II, Cr (III and Pb (II from aqueous solutions. The kinetics of biosorption are studied, analyzing the effect of the initial concentration of metal and temperature. Pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion models have been used to represent the kinetics of the process and obtain the main kinetic parameters. The results show that the pseudo-second order model is the one that best describes the biosorption of the three metal ions for all the range of experimental conditions investigated. For the three metal ions, the maximum biosoption capacity and the initial biosorption rate increase when the initial metal concentration rises. However, the kinetic constant decreases when the initial metal concentration increases. The temperature effect on biosorption capacity for Cd (II and Cr (III is less significant; however, for Pb (II the effect of temperature is more important, especially when temperature rises from 25 to 40ºC. The biosorption capacity at mmol/g of olive stone changes in the following order: Cr>Cd>Pb. Thus, for an initial concentration of 220 mg/ℓ, a maximum sorption capacity of 0.079 mmol/g for Cr (III, 0.065 mmol/g for Cd (II and 0.028 mmol/g for Pb (II has been obtained.

Thermochemical Storage of Middle Temperature Wasted Heat by Functionalized C/Mg(OH2 Hybrid Materials

Directory of Open Access Journals (Sweden)

Emanuela Mastronardo

2017-01-01

Full Text Available For the thermochemical performance implementation of Mg(OH2 as a heat storage medium, several hybrid materials have been investigated. For this study, high-performance hybrid materials have been developed by exploiting the authors’ previous findings. Expanded graphite (EG/carbon nanotubes (CNTs-Mg(OH2 hybrid materials have been prepared through Mg(OH2 deposition-precipitation over functionalized, i.e., oxidized, or un-functionalized EG or CNTs. The heat storage performances of the carbon-based hybrid materials have been investigated through a laboratory-scale experimental simulation of the heat storage/release cycles, carried out by a thermogravimetric apparatus. This study offers a critical evaluation of the thermochemical performances of developed materials through their comparison in terms of heat storage and output capacities per mass and volume unit. It was demonstrated that both EG and CNTs improves the thermochemical performances of the storage medium in terms of reaction rate and conversion with respect to pure Mg(OH2. With functionalized EG/CNTs-Mg(OH2, (i the potential heat storage and output capacities per mass unit of Mg(OH2 have been completely exploited; and (ii higher heat storage and output capacities per volume unit were obtained. That means, for technological applications, as smaller volume at equal stored/released heat.

Redetermination of di-μ-hydrido-hexahydridotetrakis(tetrahydrofurandialuminium(IIImagnesium(II

Directory of Open Access Journals (Sweden)

Hima Kumar Lingam

2010-05-01

Full Text Available The structure of the title compound, [Mg(AlH42(C4H8O4], has been redetermined at 150 K. The MgII ion is hexacoordinated to four tetrahydrofuran (THF ligands, and two AlH4− anions through bridging H atoms. The Al—H distances are more precise compared to those previously determined [Nöth et al. (1995. Chem. Ber. 128, 999–1006; Fichtner & Fuhr (2002. J. Alloys Compd, 345, 386–396]. The molecule has twofold rotation symmetry.

'Two-color' reflection multilayers for He-I and He-II resonance lines for micro-UPS using Schwarzschild objective

International Nuclear Information System (INIS)

Ejima, Takeo; Kondo, Yuzi; Watanabe, Makoto

2000-01-01

'Two-color' multilayers reflecting both He-I (58.4 nm) and He-II (30.4 nm) resonance lines have been designed and fabricated for reflection coatings of Schwarzschild objectives of micro-UPS instruments. They are designed so that their reflectances for both He-I and He-II resonance lines are more than 20%. The 'two-color' multilayers are piled double layers coated with top single layers. Fabricated are multilayers of SiC(top layer)-Mg/SiC(double layers) and SiC(top layer)-Mg/Y 2 O 3 (double layers), and their reflectances for the He-I and the He-II are 23% and 17%, and 20% and 23%, respectively

Anodic behavior of Mg in acidic AlCl3–1-ethyl-3-methyl-imidazolium chloride ionic liquid

International Nuclear Information System (INIS)

Xu, Bajin; Qu, Rui; Ling, Guoping

2014-01-01

Highlights: • A viscous layer formed at Mg/ionic liquid interface after the dissolution of Mg. • As direct evidence, photo of viscous layer at the interface was presented. • Viscous layer was resulted from accumulation of dissolved Mg(II) at interface. • Formation of viscous layer resulted in a homogenous etched Mg surface. • Dissolution model of Mg and formation mechanism of viscous layer was discussed. - Abstract: In this paper, anodic behavior of Mg in acidic AlCl 3 –1-ethyl-3-methyl-imidazolium chloride (AlCl 3 –EMIC) ionic liquid was investigated by conducting linear sweep voltammetry, chronoamperometry and chonopotentiometry. The viscosity of Mg dissolved ionic liquid and the surface morphologies of Mg were characterized using an Ostwald viscometer and a scanning electron microscopy, respectively. The results showed that the oxide film on the surface of Mg had great effects on the anodic behavior. The dissolution of Mg under anodic polarization occurred after the breakdown of oxide film. A viscous layer was observed forming at the interface of Mg/ionic liquid during the dissolution process. The formation of viscous layer was attributed to the accumulation of Mg dissolved AlCl 3 –EMIC ionic liquid at the interface, which was of high viscosity. With a viscous layer formed in the anodic process, the etched surface of Mg anode was homogeneous and flat without any etching pits. Otherwise, the Mg showed a morphology of pitting on the surface

Liraglutide 3.0 mg for Weight Management: A Population Pharmacokinetic Analysis.

Science.gov (United States)

Overgaard, Rune V; Petri, Kristin C; Jacobsen, Lisbeth V; Jensen, Christine B

2016-11-01

This analysis used a population pharmacokinetic approach to identify covariates that influence plasma exposure of liraglutide 3.0 mg, a glucagon-like peptide-1 (GLP-1) receptor agonist approved for weight management in overweight and obese individuals. Samples for pharmacokinetic analysis were drawn at weeks 2, 12 and 28 of the phase IIIa SCALE Obesity and Prediabetes (N = 2339) and SCALE Diabetes (N = 584) trials. Dose proportionality of liraglutide in obese subjects was investigated using data from a phase II dose-finding study (N = 331). Dose-proportional exposure of liraglutide up to and including 3.0 mg was confirmed. Body weight and sex influenced exposure of liraglutide 3.0 mg, while age ≥70 years, race, ethnicity and baseline glycaemic status did not. Compared with a reference subject weighing 100 kg, exposure of liraglutide 3.0 mg was 44 % lower for a subject weighing 234 kg (90 % CI 41-47), 41 % higher for a subject weighing 60 kg (90 % CI 37-46), and 32 % higher (90 % CI 28-35) in females than males with the same body weight. Neither injection site nor renal function significantly influenced exposure of liraglutide 3.0 mg (post hoc analysis). Population pharmacokinetics of liraglutide up to and including 3.0 mg daily in overweight and obese adults demonstrated dose-proportional exposure, and limited effect of covariates other than sex and body weight. These findings were similar to those previously observed with liraglutide up to 1.8 mg in subjects with type 2 diabetes mellitus. Further analysis of exposure-response relationship and its effect on dose requirements is addressed in a separate publication.

Investigation of the strontium (Sr(II)) adsorption of an alginate microsphere as a low-cost adsorbent for removal and recovery from seawater.

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Hong, Hye-Jin; Ryu, Jungho; Park, In-Su; Ryu, Taegong; Chung, Kang-Sup; Kim, Byuong-Gyu

2016-01-01

In this paper, we investigated alginate microspheres as a low-cost adsorbent for strontium (Sr(II)) removal and recovery from seawater. Alginate microspheres have demonstrated a superior adsorption capacity for Sr(II) ions (≈110 mg/g). A Freundlich isotherm model fits well with the Sr(II) adsorption of an alginate microsphere. The mechanism of Sr(II) adsorption is inferred as an ion exchange reaction with Ca(II) ions. The effects of the solution pH and co-existing ions in seawater are also investigated. Except for a pH of 1-2, Sr(II) adsorption capacity is not affected by pH. However, increasing the seawater concentration of metal cations seriously decreases Sr(II) uptake. In particular, highly concentrated (15,000 mg/L) Na(I) ions significantly interfere with Sr(II) adsorption. Sr(II) desorption was performed using 0.1 M HCl and CaCl2. Both regenerants show an excellent desorption efficiency, but the FTIR spectrum reveals that the chemical structure of the microsphere is destroyed after repeated use of HCl. Conversely, CaCl2 successfully desorbed Sr(II) without damage, and the Sr(II) adsorption capacity does not decrease after three repeated uses. The alginate microsphere was also applied to the adsorption of Sr(II) in a real seawater medium. Because of inhibition by co-existing ions, the Sr(II) adsorption capacity was decreased and the adsorption rate was retarded compared with D.I. water. Although the Sr(II) adsorption capacity was decreased, the alginate microsphere still exhibited 17.8 mg/g of Sr(II) uptake in the seawater medium. Considering its excellent Sr(II) uptake in seawater and its reusability, an alginate microsphere is an appropriate cost-effective adsorbent for the removal and recovery of Sr(II) from seawater. Copyright © 2015 Elsevier Ltd. All rights reserved.

Hydrothermal synthesis of silico-manganese nanohybrid for Cu(II) adsorption from aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Zhu, Qiufeng, E-mail: zhuqiufeng@th.btbu.edu.cn; Wang, Liting; An, Zehuan; Ye, Hong; Feng, Xudong

2016-05-15

Highlights: • A novel silico-manganese nanohybrid adsorbent (SMNA) was synthesized by a hydrothermal method. • The adsorption capacities of the SMNA for Cu(II) are lower pH dependency. • As-adsorbents are very efficient at low metal concentration and substantial amounts of Cu(II) can be removed from aqueous solution. - Abstract: A novel silico-manganese nanohybrid adsorbent (SMNA) was synthesized by a facile hydrothermal method, and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), nitrogen adsorption-desorption, Fourier transform infrared spectroscopy (FT-IR) and zeta potential measurement. The adsorption of Cu(II) ions from aqueous solution on the SMNA was investigated with variations in contact time, pH and initial Cu(II) concentration. The results showed that hydrothermal method would generate nanowire/nanorod incomplete crystallite (δ-MnO{sub 2}) adsorbent. The adsorption of Cu(II) onto SMNA increased sharply within 25 min and reached equilibrium gradually. The maximum adsorption capacities of SMNA for Cu(II) were ∼40–88 mg g{sup −1}, which was lower than δ-MnO{sub 2} (92.42 mg g{sup −1}) but had a lower pH dependency. As compared with δ-MnO{sub 2}, higher adsorption capacities of SMNA (7.5–15 wt% of silica doping amount) for Cu(II) could be observed when pH of the aqueous solution was low (<4). The pseudo-second-order model was the best choice to describe the adsorption behavior of Cu(II) onto SMNA, suggesting that the removal of Cu(II) by the as-prepared adsorbents was dominated by migration of Cu(II). The possibility of Cu(II) recovery was also investigated and it revealed that SMNA was a promising recyclable adsorbent for removal of heavy metal ions in water and wastewater treatment.

Response surface methodology optimization of nickel (II) removal using pigeon pea pod bio sorbent

International Nuclear Information System (INIS)

Aravind, J.; Lenin, C.; Nancyflavia, C.; Rashika, P.; Saravanan, S.

2015-01-01

Pod of pigeon pea (Cajanus cajan), a cellulose rich agricultural residue, was investigated for its nickel binding efficiency. The influence of key physicochemical parameters such as contact time, initial metal ion concentration, adsorbent dosage and p H on nickel (II) removal was studied. The equilibrium time was found to be 45 min. The optimum Ni (II) removal was obtained at an initial metal ion concentration of 80 mg/l, p H of 9.0 and an adsorbent dose of 400 mg/100 ml. A search for optimal combination of key variables was studied by response surface methodology for maximum removal of nickel. The experiment encompassing 17 runs was established with the aid of Box–Behnken design. Owing to the reasonable agreement between predicted and adjusted R2 value (0.9714), the corresponding quadratic model gives the most appropriate relationship between the variables and response. The optimal point obtained was located in the valid region and the optimum adsorption parameters were predicted as an initial Ni (II) concentration of 60 mg/l, p H value of 9.0 and contact time of 75 min. Under these adsorption conditions, a maximum removal of 96.54 % of initial metal concentration was demonstrated.

Characterization of hydroxybenzoic acid chelating resins: equilibrium, kinetics, and isotherm profiles for Cd(II and Pb(II uptake

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BHAVNA A. SHAH

2011-06-01

Full Text Available Chelating ion-exchange resins were synthesized by polycondensation of ortho/para hydroxybenzoic acid with resorcinol/catechol employing formaldehyde as cross-linking agent at 80±5 °C in DMF. The resins were characterized by FTIR and XRD. The uptake behaviour of synthesized resins for Cd(II and Pb(II ions have been studied depending on contact time, pH, metal ion concentration and temperature. The sorption data obtained at optimized conditions were analyzed by the Langmuir and Freundlich isotherms. Experimental data of all metal–resin system were best represented by the Freundlich isotherm. The maximum obtained sorption capacity for cadmium was 69.53 mg g-1 and 169.32 mg g-1 for Lead. The adsorption process follows first order kinetics and the specific rate constant Kr was obtained by the application of the Lagergan equation. Thermodynamic parameters ∆Gads, ∆Sads and ∆Hads were calculated for the metal–resin systems. The external diffusion rate constant (KS and the intra-particle diffusion rate constant (Kid were calculated by the Spahn–Schlunder and Weber–Morris models, respectively. The sorption process was found to follow an intra-particle diffusion phenomenon.

Angiotensin II-induced hypertension increases plasma membrane Na pump activity by enhancing Na entry in rat thick ascending limbs.

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Gonzalez-Vicente, Agustin; Garvin, Jeffrey L

2013-11-01

Thick ascending limbs (TAL) reabsorb 30% of the filtered NaCl load. Na enters the cells via apical Na-K-2Cl cotransporters and Na/H exchangers and exits via basolateral Na pumps. Chronic angiotensin II (ANG II) infusion increases net TAL Na transport and Na apical entry; however, little is known about its effects on the basolateral Na pump. We hypothesized that in rat TALs Na pump activity is enhanced by ANG II-infusion, a model of ANG II-induced hypertension. Rats were infused with 200 ng·kg(-1)·min(-1) ANG II or vehicle for 7 days, and TAL suspensions were obtained. We studied plasma membrane Na pump activity by measuring changes in 1) intracellular Na (Nai) induced by ouabain; and 2) ouabain-sensitive oxygen consumption (QO2). We found that the ouabain-sensitive rise in Nai in TALs from ANG II-infused rats was 12.8 ± 0.4 arbitrary fluorescent units (AFU)·mg(-1)·min(-1) compared with only 9.9 ± 1.1 AFU·mg(-1)·min(-1) in controls (P Na pump expression, the number of Na pumps in the plasma membrane, or the affinity for Na. When furosemide (1.1 mg·kg(-1)·day(-1)) was coinfused with ANG II, no increase in plasma membrane Na pump activity was observed. We concluded that in ANG II-induced hypertension Na pump activity is increased in the plasma membrane of TALs and that this increase is caused by the chronically enhanced Na entry occurring in this model.

Relativistic quasiparticle band structures of Mg2Si, Mg2Ge, and Mg2Sn: Consistent parameterization and prediction of Seebeck coefficients

Science.gov (United States)

Shi, Guangsha; Kioupakis, Emmanouil

2018-02-01

We apply density functional and many-body perturbation theory calculations to consistently determine and parameterize the relativistic quasiparticle band structures of Mg2Si, Mg2Ge, and Mg2Sn, and predict the Seebeck coefficient as a function of doping and temperature. The quasiparticle band gaps, including spin-orbit coupling effects, are determined to be 0.728 eV, 0.555 eV, and 0.142 eV for Mg2Si, Mg2Ge, and Mg2Sn, respectively. The inclusion of the semicore electrons of Mg, Ge, and Sn in the valence is found to be important for the accurate determination of the band gaps of Mg2Ge and Mg2Sn. We also developed a Luttinger-Kohn Hamiltonian and determined a set of band parameters to model the near-edge relativistic quasiparticle band structure consistently for all three compounds that can be applied for thermoelectric device simulations. Our calculated values for the Seebeck coefficient of all three compounds are in good agreement with the available experimental data for a broad range of temperatures and carrier concentrations. Our results indicate that quasiparticle corrections are necessary for the accurate determination of Seebeck coefficients at high temperatures at which bipolar transport becomes important.

A robust ex vivo model for evaluation of induction of apoptosis by rhTRAIL in combination with proteasome inhibitor MG132 in human premalignant cervical explants

NARCIS (Netherlands)

Hougardy, Brigitte M. T.; Reesink-Peters, Nathalie; van den Heuvel, Fiona A. J.; ten Hoor, Klaske A.; Hollema, Harry; de Vries, Elisabeth G. E.; de Jong, Steven; van der Zee, Ate G. J.

2008-01-01

Development of medical therapies for high-grade cervical intraepithelial neoplasia (CIN II/III) is hampered by the lack of CIN II/III cell lines. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induces apoptosis upon binding to its receptors DR4 or DR5. Proteasome inhibition by MG132

Adsorption of As(III), As(V) and Cu(II) on zirconium oxide immobilized alginate beads in aqueous phase.

Science.gov (United States)

Kwon, Oh-Hun; Kim, Jong-Oh; Cho, Dong-Wan; Kumar, Rahul; Baek, Seung Han; Kurade, Mayur B; Jeon, Byong-Hun

2016-10-01

A composite adsorbent to remove arsenite [As(III)], arsenate [As(V)], and copper [Cu(II)] from aqueous phase was synthesized by immobilizing zirconium oxide on alginate beads (ZOAB). The composition (wt%) of ZOAB (Zr-34.0; O-32.7; C-21.3; Ca-1.0) was confirmed by energy dispersive X-ray (EDX) analysis. Sorption studies were conducted on single and binary sorbate systems, and the effects of contact time, initial adsorbate concentration, and pH on the adsorption performance of ZOAB (pHPZC = 4.3) were monitored. The sorption process for As(III)/As(V) and Cu(II) reached an equilibrium state within 240 h and 24 h, respectively, with maximum sorption capacities of 32.3, 28.5, and 69.9 mg g(-1), respectively. The addition of Cu(II) was favorable for As(V) sorption in contrast to As(III). In the presence of 48.6 mg L(-1) Cu(II), the sorption capacity of As(V) increased from 1.5 to 3.8 mg g(-1) after 240 h. The sorption data for As(III)/As(V) and Cu(II) conformed the Freundlich and Langmuir isotherm models, respectively. The adsorption of As(III), As(V), and Cu(II) followed pseudo second order kinetics. The effect of arsenic species on Cu(II) sorption was insignificant. The results of present study demonstrated that the synthesized sorbent could be useful for the simultaneous removal of both anionic and cationic contaminants from wastewaters. Copyright © 2016 Elsevier Ltd. All rights reserved.

Intercalation of hydrotalcites with hexacyanoferrate(II) and (III)-a thermoRaman spectroscopic study

International Nuclear Information System (INIS)

Frost, Ray L.; Musumeci, Anthony W.; Bouzaid, Jocelyn; Adebajo, Moses O.; Martens, Wayde N.; Theo Kloprogge, J.

2005-01-01

Raman spectroscopy using a hot stage indicates that the intercalation of hexacyanoferrate(II) and (III) in the interlayer space of a Mg, Al hydrotalcites leads to layered solids where the intercalated species is both hexacyanoferrate(II) and (III). Raman spectroscopy shows that depending on the oxidation state of the initial hexacyanoferrate partial oxidation and reduction takes place upon intercalation. For the hexacyanoferrate(III) some partial reduction occurs during synthesis. The symmetry of the hexacyanoferrate decreases from O h existing for the free anions to D 3d in the hexacyanoferrate interlayered hydrotalcite complexes. Hot stage Raman spectroscopy reveals the oxidation of the hexacyanoferrate(II) to hexacyanoferrate(III) in the hydrotalcite interlayer with the removal of the cyanide anions above 250 deg. C. Thermal treatment causes the loss of CN ions through the observation of a band at 2080cm -1 . The hexacyanoferrate (III) interlayered Mg, Al hydrotalcites decomposes above 150 deg. C

Efeito da toxicidade de Cr (VI e Zn (II no crescimento do fungo filamentoso Aspergillus niger isolado de efluente industrial Toxicity effect of Cr (VI and Zn (II on growth of filamentous fungi Aspergillus niger isolated from industrial effluent

Directory of Open Access Journals (Sweden)

Maria do Socorro Vale

2011-09-01

Full Text Available Processos convencionais de tratamento de efluentes utilizam microrganismos vivos, o que sugere limitações relativas À toxicidade de metais para os microrganismos. O experimento consistiu em adicionar soluções monoelementares de Cr (VI e Zn(II em diferentes concentrações (0, 20, 50, 100, 200, 300, 400, 500 mg.L-1 ao meio de crescimento e observar a influência dos metais no crescimento micelial e germinativo do fungo Aspergillus Níger por verificação visual da expansão radial do micélio e da germinação de esporos, seguida de registro fotográfico. Os resultados mostraram que o metabolismo do fungo foi completamente inibido em concentrações acima de 500 mg Zn (II.L-1 e 150 mg Cr (VI.L-1. O ED50 (concentração de ingrediente ativo capaz de inibir 50% do crescimento micelial do fungo para os dois íons metálicos, nas condições estudadas, está na faixa entre 100 e 150 mg.L-1. Palavras-chave: metais pesados; inibição; crescimento micelial; Aspergillus niger; ED50.Many standard processes of wastewater treatment use live microorganisms, which suggests limitations on a metal toxicity to the microorganism. The experiment consisted in adding mono elementary solutions of Cr (VI and Zn (II at different concentrations (0, 20, 50, 100, 200, 300, 400, 500 mg.L-1 to the growth mean, and to observe the influence of metals on mycelial and germinative growth of the Aspergillus niger fungus, by means of visual observation of the radial expansion of the mycelius and the germination of spores, followed by photograph registration. The results showed that the metabolism of the fungus was completely inhibited at concentrations above 500 mg Zn (II.L-1 and 150 mg Cr (VI.L-1. The ED50 (concentration of active ingredient capable of inhibiting 50% of mycelial growth of the fungus for both metal ions, under the studied conditions, is in the range between 100 and 150 mg.L-1.

Removal of Hg(II) from aqueous solution using sodium humate as heavy metal capturing agent.

Science.gov (United States)

Wang, Shixiang; Liu, Yong; Fan, Qin; Zhou, Anlan; Fan, Lu; Mu, Yulan

2016-12-01

An environmental friendly and economic natural biopolymer-sodium humate (HA-Na) was used to capture Hg(II) from aqueous solutions, and the trapped Hg(II) (HA-Na-Hg) was then removed by aluminium coagulation. The best Hg(II) capturing performance (90.60%) was observed under the following conditions: initial pH of 7.0, coagulation pH of 6.0, HA-Na dosage of 5.0 g L -1 , Al 2 (SO 4 ) 3 .18H 2 O dosage of 4.0 g L -1 , initial Hg(II) concentration of 50 mg L -1 and capturing time of 30 min. The HA-Na compositions with the molecular weight beyond 70 kDa showed the most intense affinity toward Hg(II). The results showed that the reaction equilibrium was achieved within 10 min (pH 7.0), and could be well fitted by the pseudo-second-order kinetics model. The capturing process could be well described by the Langmuir isotherm model and the maximum capturing capacity of Hg(II) was high up to 9.80 mg g -1 at 298 K (pH 7.0). The Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analysis showed that the redox reaction between Hg(II) and HA-Na and the coordination reaction of carboxyl and hydroxy groups of HA-Na with Hg(II) were responsible for Hg(II) removal. The successive regeneration experiment showed that the capturing efficiency of humates for Hg(II) was maintained at about 51% after five capture-regeneration recycles.

Substrate and Mg doping effects in GaAs nanowires

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Perumal Kannappan

2017-10-01

Full Text Available Mg doping of GaAs nanowires has been established as a viable alternative to Be doping in order to achieve p-type electrical conductivity. Although reports on the optical properties are available, few reports exist about the physical properties of intermediate-to-high Mg doping in GaAs nanowires grown by molecular beam epitaxy (MBE on GaAs(111B and Si(111 substrates. In this work, we address this topic and present further understanding on the fundamental aspects. As the Mg doping was increased, structural and optical investigations revealed: i a lower influence of the polytypic nature of the GaAs nanowires on their electronic structure; ii a considerable reduction of the density of vertical nanowires, which is almost null for growth on Si(111; iii the occurrence of a higher WZ phase fraction, in particular for growth on Si(111; iv an increase of the activation energy to release the less bound carrier in the radiative state from nanowires grown on GaAs(111B; and v a higher influence of defects on the activation of nonradiative de-excitation channels in the case of nanowires only grown on Si(111. Back-gate field effect transistors were fabricated with individual nanowires and the p-type electrical conductivity was measured with free hole concentration ranging from 2.7 × 1016 cm−3 to 1.4 × 1017 cm−3. The estimated electrical mobility was in the range ≈0.3–39 cm2/Vs and the dominant scattering mechanism is ascribed to the WZ/ZB interfaces. Electrical and optical measurements showed a lower influence of the polytypic structure of the nanowires on their electronic structure. The involvement of Mg in one of the radiative transitions observed for growth on the Si(111 substrate is suggested.

Bauhinia variegata (Caesalpiniaceae) leaf extract: An effective treatment option in type I and type II diabetes.

Science.gov (United States)

Kulkarni, Yogesh A; Garud, Mayuresh S

2016-10-01

Among various metabolic disorders, diabetes mellitus is one of the most common disorder. Present study was designed to evaluate the effectiveness of aqueous extract of Bauhinia variegata leaves (AE) in animal models of type I and type II diabetes. Type I diabetes was induced by streptozotocin at the dose of 55mg/kg (i.p.) in male Sprague Dawley rats while type II diabetes was induced by high fat diet and streptozotocin at the dose of 35mg/kg (i.p.). Diabetic animals were treated with AE at the dose of 250, 500 and 1000mg/kg. Glipizide (5mg/kg) was used as standard treatment drug. Treatment was given for 28days. Parameters evaluated were body weight, plasma glucose, cholesterol, triglyceride, aspartate aminotransferase, alanine transaminase, alkaline phosphatase, total proteins, albumin, creatinine and bun urea nitrogen. In type II diabetes, high density lipoprotein levels in plasma and plasma insulin level were also evaluated. Histopathological study of pancreases were carried out in type I study. AE showed significant decrease in plasma glucose significantly. AE was also found to decrease cholesterol, triglyceride, creatinine and blood urea nitrogen level in both types of diabetes. AE did not show any significant effect on plasma levels of aspartate aminotransferase, alanine transaminase, alkaline phosphatase. AE was found to increase the albumin and total protein levels. Histopathological study showed that AE decreases the necrotic changes in the pancreatic tissue. Aqueous extract of B. variegata leaves was found effective in treatment of both type I and type II diabetes. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Mg1-xZnxFe2O4 nanoparticles: Interplay between cation distribution and magnetic properties

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S. Raghuvanshi

2018-04-01

Full Text Available Correlation between cationic distribution, magnetic properties of Mg1-xZnxFe2O4 (0.0 ≤ x ≤ 1.0 ferrite is demonstrated, hardly shown in literature. X-ray diffraction (XRD confirms the formation of cubic spinel nano ferrites with grain diameter between 40.8 to 55.4 nm. Energy dispersive spectroscopy (EDS confirms close agreement of Mg/Fe, Zn/Fe molar ratio, presence of all elements (Mg, Zn, Fe, O, formation of estimated ferrite composition. Zn addition (for Mg shows: i linear increase of lattice parameter aexp, accounted for replacement of an ion with higher ionic radius (Zn > Mg; ii presence of higher population of Fe3+ ions on B site, and unusual occurrence of Zn, Mg on A and B site leads to non-equilibrium cation distribution where we observe inverse to mixed structure, and is in contrast to reported literature where inverse to normal transition is reported; iii effect on A-A, A-B, B-B exchange interactions, affecting coercivity Hc, Ms. A new empirical relation is also obtained showing linear relation between saturation magnetization Ms – inversion parameter δ, oxygen parameter u4¯3m. Non-zero Y-K angle (αYK values implies Y-K type magnetic ordering in the studied samples.

Removal of mercury (II) from aqueous solution by activated carbon obtained from furfural.

Science.gov (United States)

Yardim, M F; Budinova, T; Ekinci, E; Petrov, N; Razvigorova, M; Minkova, V

2003-08-01

The adsorption of Hg(II) from aqueous solution at 293 K by activated carbon obtained from furfural is studied. The carbon is prepared by polymerization of furfural following carbonization and activation of the obtained polymer material with water vapor at 800 degrees C. Adsorption studies of Hg(II) are carried out varying some conditions: treatment time, metal ion concentration, adsorbent amount and pH. It is determined that Hg(II) adsorption follows both Langmuir and Freundlich isotherms. The adsorption capacity of the carbon is 174 mg/g. It is determined that Hg(II) uptake increases with increasing pH. Desorption studies are performed with hot water. The percent recovery of Hg(II) is 6%.

Chondrogenic differentiation of ATDC5-cells under the influence of Mg and Mg alloy degradation

Energy Technology Data Exchange (ETDEWEB)

Martinez Sanchez, Adela H., E-mail: adela.martinez@hzg.de [Helmholtz-Zentrum Geesthacht, Institute of Material Research, Department for Structural Research on Macromolecules, Geesthacht (Germany); Feyerabend, Frank; Laipple, Daniel; Willumeit-Römer, Regine [Helmholtz-Zentrum Geesthacht, Institute of Material Research, Department for Structural Research on Macromolecules, Geesthacht (Germany); Weinberg, Annelie [Department of Orthopedics and Orthopedic Surgery, Medical University of Graz (Austria); Luthringer, Bérengère J.C. [Helmholtz-Zentrum Geesthacht, Institute of Material Research, Department for Structural Research on Macromolecules, Geesthacht (Germany)

2017-03-01

Biodegradable magnesium (Mg)-based materials are a potential alternative to permanent implants for application in children. Nevertheless effects of those materials on growth plate cartilage and chondrogenesis have not been previously evaluated. In vitro differentiation of ATDC5 cells was evaluated under the influence of pure Mg (PMg), Mg with 10 wt% of gadolinium (Mg-10Gd) and Mg with 2 wt% of silver (Mg-2Ag) degradation products (extracts) and direct cell culture on the materials. Gene expression showed an inhibitory effect on ATDC5 mineralization with the three extracts and a chondrogenic potential of Mg-10Gd. Cells cultured in Mg-10Gd and Mg-2Ag extracts showed the same proliferation and morphology than cells cultured in growth conditions. Mg-10Gd induced an increase in production of ECM and a bigger cell size, similar to the effects found with differentiation conditions. An increased metabolic activity was observed in cells cultured under the influence of Mg-10Gd extracts, indicated by an acidic pH during most of the culture period. After 7 days of culture on the materials, ATDC5 growth, distribution and ECM synthesis were higher on Mg-10Gd samples, followed by Mg-2Ag and PMg, which was influenced by the homogeneity and composition of the degradation layer. This study confirmed the tolerance of ATDC5 cells to Mg-based materials and a chondrogenic effect of Mg-10Gd. Further studies in vitro and in vivo are necessary to evaluate cell reactions to those materials, as well as the effects on bone growth and the biocompatibility of the alloying system in the body. - Highlights: • Degradation of PMg, and Mg-2Ag do not influence ATDC5 cells growth and chondrogenic redifferentiation. • Mg-10Gd enhances fast chondrogenic redifferentiation and expression of hyperthrophic markers on ATDC5 cells. • Further evaluation of the effects of PMg, Mg-10Gd and Mg-2Ag in vivo are necessary to confirm its potential for application in growing bones.

Chondrogenic differentiation of ATDC5-cells under the influence of Mg and Mg alloy degradation

International Nuclear Information System (INIS)

Martinez Sanchez, Adela H.; Feyerabend, Frank; Laipple, Daniel; Willumeit-Römer, Regine; Weinberg, Annelie; Luthringer, Bérengère J.C.

2017-01-01

Biodegradable magnesium (Mg)-based materials are a potential alternative to permanent implants for application in children. Nevertheless effects of those materials on growth plate cartilage and chondrogenesis have not been previously evaluated. In vitro differentiation of ATDC5 cells was evaluated under the influence of pure Mg (PMg), Mg with 10 wt% of gadolinium (Mg-10Gd) and Mg with 2 wt% of silver (Mg-2Ag) degradation products (extracts) and direct cell culture on the materials. Gene expression showed an inhibitory effect on ATDC5 mineralization with the three extracts and a chondrogenic potential of Mg-10Gd. Cells cultured in Mg-10Gd and Mg-2Ag extracts showed the same proliferation and morphology than cells cultured in growth conditions. Mg-10Gd induced an increase in production of ECM and a bigger cell size, similar to the effects found with differentiation conditions. An increased metabolic activity was observed in cells cultured under the influence of Mg-10Gd extracts, indicated by an acidic pH during most of the culture period. After 7 days of culture on the materials, ATDC5 growth, distribution and ECM synthesis were higher on Mg-10Gd samples, followed by Mg-2Ag and PMg, which was influenced by the homogeneity and composition of the degradation layer. This study confirmed the tolerance of ATDC5 cells to Mg-based materials and a chondrogenic effect of Mg-10Gd. Further studies in vitro and in vivo are necessary to evaluate cell reactions to those materials, as well as the effects on bone growth and the biocompatibility of the alloying system in the body. - Highlights: • Degradation of PMg, and Mg-2Ag do not influence ATDC5 cells growth and chondrogenic redifferentiation. • Mg-10Gd enhances fast chondrogenic redifferentiation and expression of hyperthrophic markers on ATDC5 cells. • Further evaluation of the effects of PMg, Mg-10Gd and Mg-2Ag in vivo are necessary to confirm its potential for application in growing bones.

A Novel Apolipoprotein C-II Mimetic Peptide That Activates Lipoprotein Lipase and Decreases Serum Triglycerides in Apolipoprotein E–Knockout Mice

Science.gov (United States)

Sakurai, Toshihiro; Sakurai-Ikuta, Akiko; Sviridov, Denis; Freeman, Lita; Ahsan, Lusana; Remaley, Alan T.

2015-01-01

Apolipoprotein A-I (apoA-I) mimetic peptides are currently being developed as possible new agents for the treatment of cardiovascular disease based on their ability to promote cholesterol efflux and their other beneficial antiatherogenic properties. Many of these peptides, however, have been reported to cause transient hypertriglyceridemia due to inhibition of lipolysis by lipoprotein lipase (LPL). We describe a novel bihelical amphipathic peptide (C-II-a) that contains an amphipathic helix (18A) for binding to lipoproteins and stimulating cholesterol efflux as well as a motif based on the last helix of apolipoprotein C-II (apoC-II) that activates lipolysis by LPL. The C-II-a peptide promoted cholesterol efflux from ATP-binding cassette transporter ABCA1-transfected BHK cells similar to apoA-I mimetic peptides. Furthermore, it was shown in vitro to be comparable to the full-length apoC-II protein in activating lipolysis by LPL. When added to serum from a patient with apoC-II deficiency, it restored normal levels of LPL-induced lipolysis and also enhanced lipolysis in serum from patients with type IV and V hypertriglyceridemia. Intravenous injection of C-II-a (30 mg/kg) in apolipoprotein E–knockout mice resulted in a significant reduction of plasma cholesterol and triglycerides of 38 ± 6% and 85 ± 7%, respectively, at 4 hours. When coinjected with the 5A peptide (60 mg/kg), the C-II-a (30 mg/kg) peptide was found to completely block the hypertriglyceridemic effect of the 5A peptide in C57Bl/6 mice. In summary, C-II-a is a novel peptide based on apoC-II, which promotes cholesterol efflux and lipolysis and may therefore be useful for the treatment of apoC-II deficiency and other forms of hypertriglyceridemia. PMID:25395590

Spectrophotometric Determination of Metoprolol Tartrate in Pharmaceutical Dosage Forms on Complex Formation with Cu(II

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Mustafa Cesme

2011-06-01

Full Text Available A new, simple, sensitive and accurate spectrophotometric method has been developed for the assay of metoprolol tartrate (MPT, which is based on the complexation of drug with copper(II [Cu(II] at pH 6.0, using Britton-Robinson buffer solution, to produce a blue adduct. The latter has a maximum absorbance at 675 nm and obeys Beer’s law within the concentration range 8.5-70 mg/mL. Regression analysis of the calibration data showed a good correlation coefficient (r = 0.998 with a limit of detection of 5.56 mg/mL. The proposed procedure has been successfully applied to the determination of this drug in its tablets. In addition, the spectral data and stability constant for the binuclear copper(II complex of MPT (Cu2MPT2Cl2 have been reported.

ISORROPIA II: a computationally efficient thermodynamic equilibrium model for K+─Ca²+─Mg²+─NH4+─Na+─SO4²-─NO3-─Cl-─H2O aerosols

Directory of Open Access Journals (Sweden)

C. Fountoukis

2007-09-01

Full Text Available This study presents ISORROPIA II, a thermodynamic equilibrium model for the K+–Ca2+–Mg2+–NH4+–Na+–SO42−–NO3−–Cl−–H2O aerosol system. A comprehensive evaluation of its performance is conducted against water uptake measurements for laboratory aerosol and predictions of the SCAPE2 thermodynamic module over a wide range of atmospherically relevant conditions. The two models agree well, to within 13% for aerosol water content and total PM mass, 16% for aerosol nitrate and 6% for aerosol chloride and ammonium. Largest discrepancies were found under conditions of low RH, primarily from differences in the treatment of water uptake and solid state composition. In terms of computational speed, ISORROPIA II was more than an order of magnitude faster than SCAPE2, with robust and rapid convergence under all conditions. The addition of crustal species does not slow down the thermodynamic calculations (compared to the older ISORROPIA code because of optimizations in the activity coefficient calculation algorithm. Based on its computational rigor and performance, ISORROPIA II appears to be a highly attractive alternative for use in large scale air quality and atmospheric transport models.

Synthesis and characterization of a surface-grafted Cd(II) ion-imprinted polymer for selective separation of Cd(II) ion from aqueous solution

Energy Technology Data Exchange (ETDEWEB)

Li, Min [State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081 (China); Feng, Changgen, E-mail: cgfeng@cast.org.cn [State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081 (China); Li, Mingyu; Zeng, Qingxuan; Gan, Qiang [State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081 (China); Yang, Haiyan [Research Institute of Tsinghua University in Shenzhen, Shenzhen 518057 (China)

2015-03-30

Highlights: • Cd(II) ion-imprinted polymer (Cd(II)-IIP) is prepared. • Cd(II)-IIP shows high stability, good selectivity and reusability. • Cd(II)-IIP can be used as a sorbent for selective removal of Cd(II) ion. - Abstract: A novel Cd(II) ion-imprinted polymer (Cd(II)-IIP) was prepared with surface imprinting technology by using cadmium chloride as a template and allyl thiourea (ATU) as a functional monomer for on-line solid-phase extraction of trace Cd(II) ion and selective separation Cd(II) ion in water samples. The Cd(II)-IIP exhibited good chemical performance and thermal stability. Kinetics studies showed that the equilibrium adsorption was achieved within 8.0 min and the adsorption process can be described by pseudo-second-order kinetic model. Compared to the Cd(II) non-imprinted polymer (Cd(II)-NIP), the Cd(II)-IIP had a higher adsorption capacity and selectivity for Cd(II) ion. The maximum adsorption capacities of the Cd(II)-IIP and Cd(II)-NIP for Cd(II) were 38.30 and 13.21 mg g{sup −1}, respectively. The relative selectivity coefficients of the adsorbent for Cd(II) in the presence of Cu{sup 2+}, Ni{sup 2+}, Co{sup 2+}, Pb{sup 2+} and Zn{sup 2+} were 2.86, 6.42, 11.50, 9.46 and 3.73, respectively. In addition, the Cd(II) ion adsorbed was easy to remove from sorbent and the Cd(II)-IIP exhibited good stability and reusability. The adsorption capacity had no obvious decrease after being used six times. The accuracy of this method was verified by the standard reference material, it was then applied for cadmium ion determination in different types of water samples.

Propyl phthalimide-modified thiacalixphenyl[4]arene as a “turn on” chemosensor for Hg(II) ions

Energy Technology Data Exchange (ETDEWEB)

Modi, Krunal; Panchal, Urvi; Mehta, Viren; Panchal, Manthan; Kongor, Anita; Jain, V.K., E-mail: drvkjain@hotmail.com

2016-11-15

Thiacalixphenyl[4]arene tetra N-(3-propyl) phthalimide (TPTN3PPh), a novel thiacalixarene bearing a N-(3-bromopropyl) phthalimide group, was synthesized and characterized by Electrospray Ionization Mass Spectrometry (ESI-MS) and NMR. The ability of TPTN3PPh to recognize the cations Fe(III), Cu(II), Cd(II), Zn(II), Cr(II), Ca(II), Co(II), Mg(II), Ag(I), Pb(II), Sr(II), Hg (II), Th(II), Ba(II), Bi(II), K(I), and Na(I) was evaluated. Only Hg(II) was selectively and sensitively detected using a spectrofluorimetric method, with a detection limit as low as 3.10×10{sup −9} M. Analysis of the binding behavior of TPTN3PPh with Hg(II) revealed 1:2 complex formation. Real sample analysis detected nano levels of mercury ions in a waste water samples.

Polarographic determination of Sn (II) and total Sn in PYRO and MDP radiopharmaceutical kits

International Nuclear Information System (INIS)

Sebastian, Maria V.A.; Lugon, Marcelo Di M.V.; Silva, Jose L. da; Fukumori, Neuza T.O.; Pereira, Nilda P.S. de; Silva, Constancia P.G. da; Matsuda, Margareth M.N.

2007-01-01

A sensitive, alternative method to atom absorption spectrometry, fluorimetry or potentiometry for the evaluation of tin(II) ions (0.1- 10 mg) and total tin in radiopharmaceutical kits was investigated. Differential pulse polarography was chosen. The supporting electrolyte was H 2 SO 4 3 mol L -1 and HCl 3 mol L -1 solution. The potential was swept from -250 to -800 mV vs Ag/AgCl/saturated KCl, using a dropping mercury electrode with 1 s drop time, 50 mV s -1 scan rate, -50 mV pulse amplitude, 40 ms pulse time and 10 mV step amplitude. Pure nitrogen was used to deaerate the polarographic cell solution for 5 min, before and after each sample introduction. Oxidation of Sn(II) was made in the same sample vial by adding H 2 O 2 (hydrogen peroxide) 10 mol L -1 , at 37 deg C, in order to quantify the total Sn. The calibration curve for Sn(II) and Sn(IV) was obtained in the concentration range of 0-10 ppm from a 1000 ppm standard solution. The detection limit of Sn(II) is 0.5 ppm and for Sn(IV) is 0.6 ppm. Differential pulse polarography was performed in the pyrophosphate (PYRO) and methylenediphosphonic acid (MDP) radiopharmaceutical kits, containing 2 mg and 1 mg of SnCl 2 .2H 2 O per vial, respectively. The described method for determination of stannous ion (Sn(II)), is selective, reproducible and adequate to be used in the quality control of lyophilized reagents and it shall be performed for other cold kits produced at IPEN. (author)

Magnesium and nickel(II) furan-2,5-dicarboxylate

DEFF Research Database (Denmark)

Schau-Magnussen, Magnus; Gorbanev, Yury; Kegnæs, Søren

2011-01-01

The salts hexaaquamagnesium furan-2,5-dicarboxylate, [Mg(H2O)(6)](C6H2O5), (I), and hexaaquanickel furan-2,5-dicarboxylate, [Ni(H2O)(6)](C6H2O5), (II), provide the first crystallographic characterization of the furan-2,5-dicarboxylate dianion. Both structures exhibit extensive three-dimensional h...

Molecular characterization of a nuclear topoisomerase II from Nicotiana tabacum that functionally complements a temperature-sensitive topoisomerase II yeast mutant.

Science.gov (United States)

Singh, B N; Mudgil, Yashwanti; Sopory, S K; Reddy, M K

2003-07-01

We have successfully expressed enzymatically active plant topoisomerase II in Escherichia coli for the first time, which has enabled its biochemical characterization. Using a PCR-based strategy, we obtained a full-length cDNA and the corresponding genomic clone of tobacco topoisomerase II. The genomic clone has 18 exons interrupted by 17 introns. Most of the 5' and 3' splice junctions follow the typical canonical consensus dinucleotide sequence GU-AG present in other plant introns. The position of introns and phasing with respect to primary amino acid sequence in tobacco TopII and Arabidopsis TopII are highly conserved, suggesting that the two genes are evolved from the common ancestral type II topoisomerase gene. The cDNA encodes a polypeptide of 1482 amino acids. The primary amino acid sequence shows a striking sequence similarity, preserving all the structural domains that are conserved among eukaryotic type II topoisomerases in an identical spatial order. We have expressed the full-length polypeptide in E. coli and purified the recombinant protein to homogeneity. The full-length polypeptide relaxed supercoiled DNA and decatenated the catenated DNA in a Mg(2+)- and ATP-dependent manner, and this activity was inhibited by 4'-(9-acridinylamino)-3'-methoxymethanesulfonanilide (m-AMSA). The immunofluorescence and confocal microscopic studies, with antibodies developed against the N-terminal region of tobacco recombinant topoisomerase II, established the nuclear localization of topoisomerase II in tobacco BY2 cells. The regulated expression of tobacco topoisomerase II gene under the GAL1 promoter functionally complemented a temperature-sensitive TopII(ts) yeast mutant.

Crystal structure of catena-poly[[[aquabis(dimethylformamide-κOmagnesium(II]-μ3-(2,2′-bipyridine-5,5′-dicarboxylato-κ5O2:O2′:N,N′:O5-[dichloridoplatinum(II

Directory of Open Access Journals (Sweden)

Fredrik Lundvall

2017-07-01

Full Text Available The title compound, {[MgPtCl2(C12H6N2O4(C3H7NO2(H2O]·C3H7NO}n, is a one-dimensional coordination polymer. The structure consists of Pt-functionalized bipyridine ligands connected by MgII cations, as well as coordinating and non-coordinating solvent molecules. The PtII cation is coordinated by the two N atoms of the bipyridine moiety and two Cl atoms in a square-planar fashion. This coordination induces an in-plane bend along the bipyridine backbone of approximately 10° from the linear ideal of a conjugated π-system. Likewise, the coordination to the MgII cation induces a significant bowing of the plane of the bipyridine of about 12°, giving it a distinct curved appearance. The carboxylate groups of the bipyridine ligand exhibit moderate rotations relative to their parent pyridine rings. The MgII cation has a fairly regular octahedral coordination polyhedron, in which three vertices are occupied by O atoms from the carboxylate groups of three different bipyridine ligands. The remaining three vertices are occupied by the O atoms of two dimethylformamide (DMF molecules and one water molecule. The one-dimensional chains are oriented in the [01-1] direction, and non-coordinating DMF molecules can be found in the space between the chains. The shortest intermolecular O...H contacts are 2.844 (4 and 2.659 (4 Å, suggesting moderate hydrogen-bonding interactions. In addition, there is a short intermolecular Pt...Pt contact of 3.491 (1 Å, indicating a Pt stacking interaction. Some structure-directing contribution from the hydrogen bonding and Pt...Pt interaction is probable. However, the crystal packing seems to be directed primarily by van der Waals interactions.

Raman microspectroscopic study of effects of Na(I) and Mg(II) ions on low pH induced DNA structural changes

NARCIS (Netherlands)

Muntean, C.M.; Segers-Nolten, Gezina M.J.

2003-01-01

In this work a confocal Raman microspectrometer is used to investigate the influence of Na+ and Mg2+ ions on the DNA structural changes induced by low pH. Measurements are carried out on calf thymus DNA at neutral pH (7) and pH 3 in the presence of low and high concentrations of Na+ and Mg2+ ions,

Blood pressure, magnesium and other mineral balance in two rat models of salt-sensitive, induced hypertension: effects of a non-peptide angiotensin II receptor type 1 antagonist.

Science.gov (United States)

Rondón, Lusliany Josefina; Marcano, Eunice; Rodríguez, Fátima; del Castillo, Jesús Rafael

2014-01-01

The renin-angiotensin system is critically involved in regulating arterial blood pressure (BP). Inappropriate angiotensin type-1 receptor activation by angiotensin-II (Ang-II) is related to increased arterial BP. Mg has a role in BP; it can affect cardiac electrical activity, myocardial contractility, and vascular tone. To evaluate the relationship between high BP induced by a high sodium (Na) diet and Mg, and other mineral balances, two experimental rat models of salt-sensitive, induced-hypertension were used: Ang-II infused and Dahl salt-sensitive (SS) rats. We found that: 1) Ang-II infusion progressively increased BP, which was accompanied by hypomagnesuria and signs of secondary hyperaldosteronism; 2) an additive effect between Ang-II and a high Na load may have an effect on strontium (Sr), zinc (Zn) and copper (Cu) balances; 3) Dahl SS rats fed a high Na diet had a slow pressor response, accompanied by altered Mg, Na, potassium (K), and phosphate (P) balances; and 4) losartan prevented BP increases induced by Ang II-NaCl, but did not modify mineral balances. In Dahl SS rats, losartan attenuated high BP and ameliorated magnesemia, Na and K balances. Mg metabolism maybe considered a possible defect in this strain of rat that may contribute to hypertension.

Performance of Mg-14Li-1Al-0.1Ce as anode for Mg-air battery

Energy Technology Data Exchange (ETDEWEB)

Ma, Yibin; Li, Deyu [School of Chemical Engineering and Technology, Harbin Institute of Technology, West Street No. 92, Harbin 150001 (China); Li, Ning [School of Chemical Engineering and Technology, Harbin Institute of Technology, West Street No. 92, Harbin 150001 (China); Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, Harbin Engineering University, Harbin 150001 (China); Zhang, Milin; Huang, Xiaomei [Key Laboratory of Superlight Materials and Surface Technology, Ministry of Education, Harbin Engineering University, Harbin 150001 (China)

2011-02-15

In this research, a new Mg-air battery based on Mg-14Li-1Al-0.1Ce was prepared and the battery performance was investigated by constant current discharge test. The corrosion behavior of Mg, AZ31 and Mg-Li-Al-Ce were studied by self-corrosion rate measurement and potentiodynamic polarization measurement. The characteristics of Mg-Li-Al-Ce after discharge were investigated by electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results show that Mg-Li-Al-Ce is more active than Mg and AZ31. The self-corrosion rate is found to be in the order: Mg-Li-Al-Ce < Mg < AZ31. It has been observed that the Mg-air battery based on Mg-Li-Al-Ce offers higher operating voltage, anodic efficiency and capacity than those with Mg and AZ31. SEM and EIS results show that the discharge product of Mg-Li-Al-Ce is loosely adhered to the alloy surface, and thus Mg-Li-Al-Ce could keep high discharge activity during discharge. (author)

Indirect iodometric procedure for quantitation of Sn(II) in radiopharmaceutical kits

International Nuclear Information System (INIS)

Muddukrishna, S.N.; Chen, A.; Sykes, T.R.; Noujaim, A.A.; Alberta Univ., Edmonton, AB

1994-01-01

A method of quantitating stannous ion [Sn(II)] suitable for radiopharmaceutical kits, based on indirect iodometric titration, is described. The method is based on the oxidation of Sn(II) using a known excess of iodine and the excess unreacted iodine determined using thiosulphate by potentiometric titration. The titration cell is a beaker and the titrations are done conveniently under air using an autotitrator in approx. 4 min. The method is accurate and is linear in the range of approx. 10 μg to approx. 6 mg of Sn(II). Several radiopharmaceutical kits were analysed for their Sn(II) content using the method including those containing antibodies or other proteins. The studies indicate that the procedure is rapid, simple and accurate for routine quantitative estimation of Sn(II) in radiopharmaceutical preparations during development, manufacture and storage. (Author)

Mifepristone 5 mg versus 10 mg for emergency contraception: double-blind randomized clinical trial

Directory of Open Access Journals (Sweden)

Carbonell JL

2015-01-01

Full Text Available Josep Lluis Carbonell,1 Ramon Garcia,2 Adriana Gonzalez,2 Andres Breto,2 Carlos Sanchez2 1Mediterranea Medica Clinic, Valencia, Spain; 2Eusebio Hernandez Gynecology and Obstetrics Teaching Hospital, Havana, Cuba Purpose: To estimate the efficacy and safety of 5 mg and 10 mg mifepristone for emergency contraception up to 144 hours after unprotected coitus. Methods: This double-blind randomized clinical trial was carried out at Eusebio Hernandez Hospital (Havana, Cuba. A total of 2,418 women who requested emergency contraception after unprotected coitus received either 5 mg or 10 mg mifepristone. The variables for assessing efficacy were the pregnancies that occurred and the fraction of pregnancies that were prevented. Other variables assessed were the side effects of mifepristone, vaginal bleeding, and changes in the date of the following menstruation. Results: There were 15/1,206 (1.2% and 9/1,212 (0.7% pregnancies in the 5 mg and 10 mg group, respectively (P=0.107. There were 88% and 93% prevented pregnancies in the 5 mg and 10 mg group, respectively. The side effect profiles were similar in both groups. Delayed menstruation ≥7 days was experienced by 4.9% and 11.0% of subjects in the 5 mg and 10 mg group, respectively (P=0.001. There was a significant high failure rate for women weighing >75 kg in the 5 mg group. Conclusion: It would be advisable to use the 10 mg dose of mifepristone for emergency contraception as there was a trend suggesting that the failure rate of the larger dose was lower. Keywords: mifepristone, emergency contraception

Chondrogenic differentiation of ATDC5-cells under the influence of Mg and Mg alloy degradation.

Science.gov (United States)

Martinez Sanchez, Adela H; Feyerabend, Frank; Laipple, Daniel; Willumeit-Römer, Regine; Weinberg, Annelie; Luthringer, Bérengère J C

2017-03-01

Biodegradable magnesium (Mg)-based materials are a potential alternative to permanent implants for application in children. Nevertheless effects of those materials on growth plate cartilage and chondrogenesis have not been previously evaluated. In vitro differentiation of ATDC5 cells was evaluated under the influence of pure Mg (PMg), Mg with 10wt% of gadolinium (Mg-10Gd) and Mg with 2wt% of silver (Mg-2Ag) degradation products (extracts) and direct cell culture on the materials. Gene expression showed an inhibitory effect on ATDC5 mineralization with the three extracts and a chondrogenic potential of Mg-10Gd. Cells cultured in Mg-10Gd and Mg-2Ag extracts showed the same proliferation and morphology than cells cultured in growth conditions. Mg-10Gd induced an increase in production of ECM and a bigger cell size, similar to the effects found with differentiation conditions. An increased metabolic activity was observed in cells cultured under the influence of Mg-10Gd extracts, indicated by an acidic pH during most of the culture period. After 7days of culture on the materials, ATDC5 growth, distribution and ECM synthesis were higher on Mg-10Gd samples, followed by Mg-2Ag and PMg, which was influenced by the homogeneity and composition of the degradation layer. This study confirmed the tolerance of ATDC5 cells to Mg-based materials and a chondrogenic effect of Mg-10Gd. Further studies in vitro and in vivo are necessary to evaluate cell reactions to those materials, as well as the effects on bone growth and the biocompatibility of the alloying system in the body. Copyright © 2016 Elsevier B.V. All rights reserved.

Evaluation of sorption capacity of scrap tyre in the removal of copper (II) ion from aqua system

International Nuclear Information System (INIS)

Oladoja, N.A.; Ofomaja, A.; Ebare, E.; Ebare, E.

2006-01-01

The use of scrap-tyre (ST), which was both a waste and pollutant was investigated as a low-cost sorbent to sorbed Cu (II) from aqueous solution. The influence of pH, sorbent dosage, contact time, and initial sorbate concentration on the uptake of Cu (II) by ST were studied. Optimum sorption of Cu (II) by ST was achieved at pH 6. The amount Of sorbate sorbed per gram of sorbent decreased with increase in sorbent dosage. Maximum uptake of the Cu (II) was achieved within the first thirty minutes of contact between the ST and the Cu (II). The equilibrium relationship between the concentration of the Cu (II) in the fluid phase and the concentration in the ST particles at a given temperature showed that the sorption mechanism was like adsorption rather than distribution into any phase. Analysis of the result using Langmuir and Freundlich models showed that it conformed to Langmuir equation based on the formation of a monomolecular layer. The adsorption capacity due to monolayer coverage was 12.95 mg/g, while the energy of adsorption was 3.95 dm/mg. (author)

Exposure-response analyses of liraglutide 3.0 mg for weight management.

Science.gov (United States)

Wilding, J P H; Overgaard, R V; Jacobsen, L V; Jensen, C B; le Roux, C W

2016-05-01

Liraglutide 3.0 mg, an acylated GLP-1 analogue approved for weight management, lowers body weight through decreased energy intake. We conducted exposure-response analyses to provide important information on individual responses to given drug doses, reflecting inter-individual variations in drug metabolism, absorption and excretion. We report efficacy and safety responses across a wide range of exposure levels, using data from one phase II (liraglutide doses 1.2, 1.8, 2.4 and 3.0 mg), and two phase IIIa [SCALE Obesity and Prediabetes (3.0 mg); SCALE Diabetes (1.8; 3.0 mg)] randomized, placebo-controlled trials (n = 4372). There was a clear exposure-weight loss response. Weight loss increased with greater exposure and appeared to level off at the highest exposures associated with liraglutide 3.0 mg in most individuals, but did not fully plateau in men. In individuals with overweight/obesity and comorbid type 2 diabetes, there was a clear exposure-glycated haemoglobin (HbA1c) relationship. HbA1c reduction increased with higher plasma liraglutide concentration (plateauing at ∼21 nM); however, for individuals with baseline HbA1c >8.5%, HbA1c reduction did not fully plateau. No exposure-response relationship was identified for any safety outcome, with the exception of gastrointestinal adverse events (AEs). Individuals with gallbladder AEs, acute pancreatitis or malignant/breast/benign colorectal neoplasms did not have higher liraglutide exposure compared with the overall population. These analyses support the use of liraglutide 3.0 mg for weight management in all subgroups investigated; weight loss increased with higher drug exposure, with no concomitant deterioration in safety/tolerability besides previously known gastrointestinal side effects. © 2016 John Wiley & Sons Ltd.

Exposure–response analyses of liraglutide 3.0 mg for weight management

Science.gov (United States)

Overgaard, R. V.; Jacobsen, L. V.; Jensen, C. B.; le Roux, C. W.

2016-01-01

Aims Liraglutide 3.0 mg, an acylated GLP‐1 analogue approved for weight management, lowers body weight through decreased energy intake. We conducted exposure‐response analyses to provide important information on individual responses to given drug doses, reflecting inter‐individual variations in drug metabolism, absorption and excretion. Methods We report efficacy and safety responses across a wide range of exposure levels, using data from one phase II (liraglutide doses 1.2, 1.8, 2.4 and 3.0 mg), and two phase IIIa [SCALE Obesity and Prediabetes (3.0 mg); SCALE Diabetes (1.8; 3.0 mg)] randomized, placebo‐controlled trials (n = 4372). Results There was a clear exposure–weight loss response. Weight loss increased with greater exposure and appeared to level off at the highest exposures associated with liraglutide 3.0 mg in most individuals, but did not fully plateau in men. In individuals with overweight/obesity and comorbid type 2 diabetes, there was a clear exposure–glycated haemoglobin (HbA1c) relationship. HbA1c reduction increased with higher plasma liraglutide concentration (plateauing at ∼21 nM); however, for individuals with baseline HbA1c >8.5%, HbA1c reduction did not fully plateau. No exposure–response relationship was identified for any safety outcome, with the exception of gastrointestinal adverse events (AEs). Individuals with gallbladder AEs, acute pancreatitis or malignant/breast/benign colorectal neoplasms did not have higher liraglutide exposure compared with the overall population. Conclusions These analyses support the use of liraglutide 3.0 mg for weight management in all subgroups investigated; weight loss increased with higher drug exposure, with no concomitant deterioration in safety/tolerability besides previously known gastrointestinal side effects. PMID:26833744

Biosorption characteristic of Alcaligenes sp. BAPb.1 for removal of lead(II) from aqueous solution.

Science.gov (United States)

Jin, Yu; Yu, Sumei; Teng, Chunying; Song, Tao; Dong, Liying; Liang, Jinsong; Bai, Xin; Xu, Xiuhong; Qu, Juanjuan

2017-06-01

In this study, strain BAPb.1 was isolated from lead mining area and used as an adsorbent to remove lead(II) ions from aqueous solution. The physicochemical characteristics, heavy metal resistance and antibiotic sensitivity of strain BAPb.1 were investigated. Biosorption capacity was evaluated by batch biosorption experiments, and isothermal characteristics were discussed. Atomic force microscopy (AFM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectrometry (FTIR) were conducted to explore the mechanism for lead(II) adsorption. Based on morphological and physiological characteristics as well as the phylogenetic analysis of 16S rDNA sequences, strain BAPb.1 was identified as a member of the genus Alcaligenes. It exhibited high resistances to multiple heavy metals such as lead(II), copper(II), zinc(II), nickel(II) and chromium(VI), and to antibiotics such as kanamycin, ampicillin, streptomycin, chloramphenicol, and tetracycline. The optimum conditions for maximum biosorption rate of 85.2% and maximum capacity of 56.8 mg g -1 were found at pH of 5, adsorbent dosage of 1.5 g L -1 (dry weight), initial lead(II) concentration of 100 mg L -1 , and contact time of 30 min at 30 °C. Biosorption isotherms were well fitted with Langmuir isotherm model. Mechanism analysis reveals that the lead(II) ions may exchange with sodium and potassium ions, and the hydroxyl, carbonyl and phosphate groups on the cell surface can chelate the lead(II) ions, therefore, surface adsorption play significant role in the biosorption process.

Electronic structure of ferromagnet-insulator interfaces: Fe/MgO and Co/MgO

Energy Technology Data Exchange (ETDEWEB)

Mueller, M.

2007-07-11

In this thesis the electronic structure of Fe/MgO{sub x} and Co/MgO{sub x} ferromagnet-insulator interfaces, representing material systems which are widely used in magnetic tunnel junctions, is studied by means of spin- and angle-resolved photoemission spectroscopy. The photoemission studies focus particularly on the response of the ferromagnetic electronic system in contact with MgO of varying stoichiometries, as this reflects the mechanisms of metal-oxide bonding at real ferromagnet-insulator interfaces. The correlation between chemical bonding and electronic structure formation is analyzed by combining information from core- and valence-band photoemission spectroscopy. The spectral features are compared to band structure calculations, which are performed using the SPR-KKR method. The Fe/MgO and Co/MgO systems are prepared by molecular beam epitaxy under ultrahigh vacuum conditions on well-defined (4 x 6) GaAs(001) substrates. A structural analysis by means of low-energy electron diffraction (LEED) reveals their body-centered cubic crystalline structure, whereas the chemical characterization by Auger electron spectroscopy is used to quantify the chemical environment at the sample surfaces. The magnetic analysis, using the magneto-optical Kerr effect, reveals the uniaxial anisotropy of the ferromagnetic layers. A crucial parameter is given by the MgO degree of oxidation, which is addressed by means of core-level spectroscopy and quantified by suitable fitting procedures of the Mg 2p core level. The results of the photoemission experiments show, that the electronic structure of the Fe/MgO and Co/MgO ferromagnet/insulator interfaces and, consequently, the interfacial spin polarization are sensitively controlled by the interface chemistry. In particular, three distinct scenarios are identified: the nearly stoichiometric, the oxygen-deficient and the over-oxidized ferromagnet/MgO interface. Each case is defined by innate characteristics of the electronic structure at

Polyethylene imine modified hydrochar adsorption for chromium (VI) and nickel (II) removal from aqueous solution.

Science.gov (United States)

Shi, Yuanji; Zhang, Tao; Ren, Hongqiang; Kruse, Andrea; Cui, Ruofan

2018-01-01

An adsorbent hydrochar was synthesized from corn cobs and modified with polyethylene imine (PEI). The hydrochars before and after modification were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis. FTIR and XPS revealed that the PEI was grafted onto the hydrochar via ether and imine bonds formed with glutaraldehyde. The maximum adsorption capacities for Cr(VI) (33.663mg/g) and Ni(II) (29.059mg/g) on the modified hydrochars were 365% and 43.7% higher, respectively, than those on the unmodified hydrochar. A pseudo-second-order model described the adsorption of Ni(II) and Cr(VI) on all the adsorbents. The adsorption of Cr(VI) was endothermic, spontaneous, increased disorder, and obeyed the Langmuir model. By contrast, the adsorption of Ni(II) was exothermic, spontaneous, decreased disorder, and obeyed the Freundlich model. XPS confirmed that the adsorption sites and mechanisms for Ni(II) and Cr(VI) on the modified hydrochars were different. Copyright © 2017 Elsevier Ltd. All rights reserved.

Performance and mechanism of simultaneous removal of Cd(II) and Congo red from aqueous solution by hierarchical vaterite spherulites

Science.gov (United States)

Chen, Yuan-Yuan; Yu, Sheng-Hui; Jiang, Hao-Fan; Yao, Qi-Zhi; Fu, Sheng-Quan; Zhou, Gen-Tao

2018-06-01

Hierarchical vaterite spherulites, synthesized by a simple injection-precipitation method at room temperature, were applied for the simultaneous removal of heavy metal Cd(II) and dye Congo red (CR) from aqueous solution. Batch experiments reveal that the maximum removal capacities of as-prepared vaterite spherulites to Cd(II) and CR are 984.5 and 89.0 mg/g, respectively, showing excellent removal performance for Cd(II) and CR. Furthermore, in the binary Cd(II)-CR system, the removal capacity of vaterite to Cd(II) is significantly enhanced at lower CR concentration (100 mg/L). In contrast, the concurrent Cd(II) shows negligible effect on the CR removal. The simultaneous removal mechanism was investigated by FESEM, EDX, XRD, FT-IR and XPS techniques. The simultaneous removal of Cd(II) and CR in the binary system is shown to be a multistep process, involving the preferential adsorption of dye CR, stabilization of CR to vaterite, coordination of the adsorbed CR molecules with Cd(II), and transformation of vaterite into otavite. Given the facile and green synthesis procedure, and effective removal of Cd(II) and CR in the binary system, the obtained vaterite spherulites have considerable practical interest in integrative treatment of wastewater contaminated by heavy metals and dyes.

Raman microspectroscopic study of effects of Na(I) and Mg(II) ions on low pH induced DNA structural changes.

Science.gov (United States)

Muntean, C M; Segers-Nolten, G M J

2003-01-01

In this work a confocal Raman microspectrometer is used to investigate the influence of Na(+) and Mg(2+) ions on the DNA structural changes induced by low pH. Measurements are carried out on calf thymus DNA at neutral pH (7) and pH 3 in the presence of low and high concentrations of Na(+) and Mg(2+) ions, respectively. It is found that low concentrations of Na(+) ions do not protect DNA against binding of H(+). High concentrations of monovalent ions can prevent protonation of the DNA double helix. Our Raman spectra show that low concentrations of Mg(2+) ions partly protect DNA against protonation of cytosine (line at 1262 cm(-1)) but do not protect adenine and guanine N(7) against binding of H(+) (characteristic lines at 1304 and 1488 cm(-1), respectively). High concentrations of Mg(2+) can prevent protonation of cytosine and protonation of adenine (disruption of AT pairs). By analyzing the line at 1488 cm(-1), which obtains most of its intensity from a guanine vibration, high magnesium salt protect the N(7) of guanine against protonation. A high salt concentration can prevent protonation of guanine, cytosine, and adenine in DNA. Higher salt concentrations cause less DNA protonation than lower salt concentrations. Magnesium ions are found to be more effective in protecting DNA against binding of H(+) as compared with calcium ions presented in a previous study. Divalent metal cations (Mg(2+), Ca(2+)) are more effective in protecting DNA against protonation than monovalent ions (Na(+)). Copyright 2003 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 72: 000-000, 2003

FRACTIONAL RECRYSTALLIZATION KINETICS IN DIRECTLY COLD ROLLED Al-Mg, Al-Mg-Sc AND Al-Mg-Sc-Zr ALLOY

Directory of Open Access Journals (Sweden)

M. S. Kaiser

2014-12-01

Full Text Available The evaluation of texture as a function of recrystallization has been characterized for directly cold rolled Al-6Mg, Al-6Mg-0.4Sc and Al-6Mg-0.4Sc-0.2Zr alloys. Samples were annealed isothermally at 400 °C for 1 to 240 minutes to allow recrystallization. Recrystallization kinetics of the alloys is analyzed from the micro-hardness variation. Isothermally annealed samples of aluminum alloys were also studied using JMAK type analysis to see if there exists any correlation between the methods. Recrystallization fraction behavior between two methods the scandium added alloys show the higher variation due to precipitation hardening and higher recrystallization behavior. The scandium and zirconium as a combined shows the more variation due to formation of Al3(Sc, Zr precipitate. From the microstructure it is also observed that the base Al-Mg alloy attained almost fully re-crystallized state after annealing at 400 °C for 60 minutes

Investigation of the 26Mg(d, p)27Mg reaction

NARCIS (Netherlands)

Meurders, F.; Steld, A. van der

1974-01-01

The angular distributions of 31 protons groups from the 26Mg(d, p)27Mg reaction have been measured at Ed = 12.0 MeV with a split-pole magnetic spectrograph. Excitation energies have been determined for 29 bound states. Three new levels have been found. A DWBA analysis yields ln values for 19 levels;

The use of a polymer inclusion membrane in a paper-based sensor for the selective determination of Cu(II).

Science.gov (United States)

Jayawardane, B Manori; Coo, Lilibeth dlC; Cattrall, Robert W; Kolev, Spas D

2013-11-25

A disposable paper-based sensor (PBS) is described for the determination of Cu(II) in natural and waste waters at approximately 2 cents per measurement. The device makes use of a polymer inclusion membrane (PIM) to provide the selectivity for Cu(II). The PIM consists of 40 wt% di(2-ethlyhexyl) phosphoric acid (D2EHPA) as the carrier, 10 wt% dioctyl phthalate (DOP) as a plasticizer, 49.5 wt% poly(vinyl chloride) (PVC) as the base polymer and 0.5 wt% (mm(-1)) 1-(2'-pyridylazo)-2-naphthol (PAN) as the colourimetric reagent. High selectivity under mildly acidic conditions (HCl, pH 2.0) is achieved for Cu(II) in the presence of frequently encountered metal ions in natural and waste waters such as Fe(III), Al(III), Zn(II), Cd(II), Pb(II), Ca(II), Mg(II), and Ni(II). The laminated PBS consists of a PIM sensing disc (2mm in diameter) attached to the centre of a circular hydrophilic zone (7 mm in diameter) pretreated with 0.01 M HCl. This hydrophilic zone separates the sample port (a circular hole in the plastic cover) from the PIM sensing disc. After introducing 19.2 μL of a sample/standard solution to the sample port, Cu(II) diffuses across the hydrophilic zone and is extracted into the PIM disc as the Cu(II)-D2EHPA complex which subsequently reacts with PAN to produce the red-purple coloured Cu(II)-PAN complex. The colour intensity of the PIM disc is measured 15 min after sample/standard introduction by scanning using a flatbed scanner. Under optimal conditions the device is characterized by a limit of detection (LOD) and limit of quantitation (LOQ) of 0.06 and 0.21 mg L(-1) Cu(II), respectively, with two linear ranges together covering the Cu(II) concentration range from 0.1 to 30.0 mg L(-1). The PBS was successfully applied to the determination of Cu(II) in hot tap water and mine tailings water. Copyright © 2013 Elsevier B.V. All rights reserved.

Preliminary study of the characteristics of a high Mg containing Al-Mg-Si alloy

International Nuclear Information System (INIS)

Yan, F; McKay, B J; Fan, Z; Chen, M F

2012-01-01

An Al-20Mg-4Si high Mg containing alloy has been produced and its characteristics investigated. The as-cast alloy revealed primary Mg 2 Si particles evenly distributed throughout an α-Al matrix with a β-Al 3 Mg 2 fully divorced eutectic phase observed in interdendritic regions. The Mg 2 Si particles displayed octahedral, truncated octahedral, and hopper morphologies. Additions of Sb, Ti and Zr had a refining influence reducing the size of the Mg 2 Si from 52 ± 4 μm to 25 ± 0.1 μm, 35 ± 1 μm and 34 ± 1 μm respectively. HPDC tensile test samples could be produced with a 0.6 wt.% Mn addition which prevented die soldering. Solution heating for 1 hr was found to dissolve the majority of the Al 3 Mg 2 eutectic phase with no evidence of any effect on the primary Mg 2 Si. Preliminary results indicate that the heat treatment has a beneficial effect on the elongation and the UTS.

Comparative assessment of gastrointestinal irritant potency in man of tin(II) chloride and tin migrated from packaging.

Science.gov (United States)

Boogaard, Peter J; Boisset, Michel; Blunden, Steve; Davies, Scot; Ong, Teng Jin; Taverne, Jean-Pierre

2003-12-01

Tin is present in low concentrations in most canned foods and beverages, the highest levels being found in products packaged in unlacquered or partially lacquered tinplate cans. A limited number of case-reports of acute gastrointestinal disorders after consumption of food containing 100-500 mg/kg tin have been reported, but these reports suffer many insufficiencies. Controlled clinical studies on acute effects of tin migrated from packaging suggest a threshold concentration for adverse effects (AEs) of >730 mg/kg. Two separate randomised, single-centre, double-blind, crossover studies, enabling comparison of the tolerability of tin added as tin(II) chloride at concentrations of soup in 24 volunteers (Study 2) were carried out. Distribution studies were conducted to get insight in the acute AEs of low molecular weight (clear dose-response relationship was only observed when tin was added as tin(II) chloride in tomato juice. No clinically significant AEs were reported in Study 2 and comparison of the incidence of tin-related AEs showed no difference between the dose levels (including control). Tin species of low molecular weight in supernatant represented 31-32% of total tin in canned tomato soup versus 56-61% in juice freshly spiked with tin(II) chloride. Differences in the incidence of AEs following administration of tomato juice with 161 and 264 mg of tin per kg and tomato soup with 201 and 267 mg of tin per kg likely results from differences in the concentration of low molecular weight tin species and in the nature of tin complexes formed. The results of this work demonstrate that tin levels up to 267 mg/kg in canned food cause no AEs in healthy adults and support the currently proposed tin levels of 200 mg/kg and 250 mg/kg for canned beverages and canned foods, respectively, as safe levels for adults in the general population.

A Computational Investigation of Precipitates in Mg-RE Alloys With Applications To Mg-X Systems

Science.gov (United States)

Issa, Ahmed

Increasing fuel efficiency in transportation vehicles is a major policy goal for both government and auto and aerospace manufacturers. Lightweight structural materials, such as magnesium alloys, hold great promise in enabling such fuel efficiency gains. Understanding the controlling factors in Mg alloy strengthening is crucial for the rational design of structurally strong and inexpensive Mg alloys. In this work, we seek to understand the energetic underpinnings giving rise to a class of remarkably strong Mg alloys: Mg-RE systems. We use first-principles methods to efficiently explore seventeen Mg-RE systems, drawing out broad patterns and distilling our knowledge into simple design rules for Mg alloys. We begin by investigating the controlling factors for the Mg-strengthening prismatic plate precipitates in Mg-RE systems, discovering the critical role of strain in such systems. We then proceed to investigate the surprising role of interfacial energies in determining the course of the Mg-RE precipitation reactions. Using strain and interfacial energies, we construct a phase-field model which accurately depicts the precipitate morphology as a function of time and size in a Mg-Nd system. Finally, we combine our gained insights to implement a computational alloy design scheme on a large portion of the periodic table where we seek Mg-strengthening solutes. Our work advances the understanding of strengthening in Mg alloys and lays the groundwork for full scale computational alloy design.

The role of MgO content in ex situ MgB₂ wires

DEFF Research Database (Denmark)

Kovac, P.; Hugek, I.; Meligek, T.

2004-01-01

An experimental study of the effect of MgO content in the MgB2 powder used for ex situ made composite wires was carried out. Two single-core MgB2/Fe/Cu wires were made using commercial MgB2 powders from Alfa Aesar containing different fraction of MgO. Critical temperature and critical currents of...

Reduced glomerular angiotensin II receptor density in diabetes mellitus in the rat: time course and mechanism

International Nuclear Information System (INIS)

Wilkes, B.M.

1987-01-01

Glomerular angiotensin II receptors are reduced in number in early diabetes mellitus, which may contribute to hyperfiltration and glomerular injury. The time course and role of the renin-angiotensin-aldosterone system in the pathogenesis of the receptor abnormality were studied in male Sprague-Dawley rats made diabetic with streptozotocin (65 mg, iv). Glomerular angiotensin II receptors were measured by Scatchard analysis; insulin, renin activity, angiotensin II, and aldosterone were measured by RIA. Diabetes mellitus was documented at 24 h by a rise in plasma glucose (vehicle-injected control, 133 +/- 4; diabetic, 482 +/- 22 mg/dl and a fall in plasma insulin (control, 53.1 +/- 5.7; diabetic, 35.6 +/- 4.0 microIU/ml. At 24 h glomerular angiotensin II receptor density was decreased by 26.5% in diabetic rats (control, 75.5 +/- 9.6 X 10(6); diabetic, 55.5 +/- 8.3 X 10(6) receptors/glomerulus. Receptor occupancy could not explain the defect, because there was reduced binding in diabetic glomeruli after pretreatment with 3 M MgCl 2 , a maneuver that caused dissociation of previously bound hormone. There was a progressive return of the receptor density toward normal over the 60 days following induction of diabetes, with diabetic glomeruli measuring 22.7%, 14.8%, and 3.7% fewer receptors than age-matched controls at 11 days, 1 month, and 2 months, respectively

Investigation of the 24Mg(d, p)25Mg reaction

NARCIS (Netherlands)

Meurders, F.; Korte, G. de

1975-01-01

Abstract Proton angular distributions from the 24Mg(d, p)25Mg reaction at Ed = 12.0 MeV have been measured with a split-pole magnetic spectrograph for Ex < 6 MeV at an average resolution (FWHM) of 7 keV. New ln values have been determined for three levels. A DWBA analysis yielded spectroscopic

Formation and Corrosion Resistance of Mg-Al Hydrotalcite Film on Mg-Gd-Zn Alloy

Science.gov (United States)

Ba, Z. X.; Dong, Q. S.; Kong, S. X.; Zhang, X. B.; Xue, Y. J.; Chen, Y. J.

2017-06-01

An environment-friendly technique for depositing a Mg-Al hydrotalcite (HT) (Mg6Al2(OH)16-CO3ṡ4H2O) conversion film was developed to protect the Mg-Gd-Zn alloy from corrosion. The morphology and chemical compositions of the film were analyzed by scanning electronic microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD) and Raman spectroscopy (RS), respectively. The electrochemical test and hydrogen evolution test were employed to evaluate the biocorrosion behavior of Mg-Gd-Zn alloy coated with the Mg-Al HT film in the simulated body fluid (SBF). It was found that the formation of Mg-Al HT film was a transition from amorphous precursor to a crystalline HT structure. The HT film can effectively improve the corrosion resistance of magnesium alloy. It indicates that the process provides a promising approach to modify Mg-Gd-Zn alloy.

Adsorption study of copper (II) by chemically modified orange peel

International Nuclear Information System (INIS)

Feng Ningchuan; Guo Xueyi; Liang Sha

2009-01-01

An adsorbent, the chemically modified orange peel, was prepared from hydrolysis of the grafted copolymer, which was synthesized by interaction of methyl acrylate with cross-linking orange peel. The presence of poly (acrylic acid) on the biomass surface was verified by infrared spectroscopy (IR), scanning electron microscopy (SEM) and thermogravimetry (TG). Total negative charge in the biomass surface and the zeta potentials were determined. The modified biomass was found to present high adsorption capacity and fast adsorption rate for Cu (II). From Langmuir isotherm, the adsorption capacity for Cu (II) was 289.0 mg g -1 , which is about 6.5 times higher than that of the unmodified biomass. The kinetics for Cu (II) adsorption followed the pseudo-second-order kinetics. The adsorbent was used to remove Cu (II) from electroplating wastewater and was suitable for repeated use for more than four cycles.

Hg(II) removal from aqueous solutions by bacillus subtilis biomass

Energy Technology Data Exchange (ETDEWEB)

Wang, Xue Song; Li, Fei Yan; He, Wen; Miao, Hua Hua [Department of Chemical Engineering, Huaihai Institute of Technology, Lianyungang (China)

2010-01-15

The biosorption of Hg(II) from aqueous solutions using Bacillus subtilis biomass was investigated in this study. The adsorbent was characterized by FTIR. Various factors including solution pH, initial concentration of Hg(II), contact time, reaction temperature and ionic strength were taken into account and promising results were obtained. An initial solution pH of 5.0 was most favorable for Hg(II) removal. The kinetic data was also analyzed using pseudo first order and pseudo second order equations. The results suggested that Hg(II) bioadsorption was best represented by the pseudo second order equation. Freundlich, Langmuir and Langmuir-Freundlich isotherms for the present systems were analyzed. The most satisfactory interpretation for the equilibrium data at different temperatures was given by the Langmuir-Freundlich isotherm. The effect of ionic strength on bioadsorption was significant. Bacillus subtilis biomass could serve as low cost adsorbent to remove Hg(II) from aqueous solutions, especially at lower concentrations of Hg(II) (<20 mg Hg/L). (Abstract Copyright [2010], Wiley Periodicals, Inc.)

Tartrazine modified activated carbon for the removal of Pb(II), Cd(II) and Cr(III).

Science.gov (United States)

Monser, Lotfi; Adhoum, Nafaâ

2009-01-15

A two in one attempt for the removal of tartrazine and metal ions on activated carbon has been developed. The method was based on the modification of activated carbon with tartrazine then its application for the removal of Pb(II), Cd(II) and Cr(III) ions at different pH values. Tartrazine adsorption data were modelled using both Langmuir and Freundlich classical adsorption isotherms. The adsorption capacities qm were 121.3, 67 and 56.7mgg(-1) at initial pH values of 1.0, 6.0 and 10, respectively. The adsorption of tartrazine onto activated carbon followed second-order kinetic model. The equilibrium time was found to be 240min at pH 1.0 and 120min at pH 10 for 500mgL(-1) tartrazine concentration. A maximum removal of 85% was obtained after 1h of contact time. The presence of tartrazine as modifier enhances attractive electrostatic interactions between metal ions and carbon surface. The adsorption capacity for Pb(II), Cd(II) and Cr(III) ions has been improved with respect to non-modified carbon reaching a maximum of 140%. The adsorption capacity was found to be a pH dependent for both modified and non-modified carbon with a greater adsorption at higher pH values except for Cr(III). The enhancement percent of Pb(II), Cd(II) and Cr(III) at different pH values was varied from 28% to 140% with respect to non-modified carbon. The amount of metal ions adsorbed using static regime was 11-40% higher than that with dynamic mode. The difference between adsorption capacities could be attributed to the applied flow rate.

Melting relations in the MgO-MgSiO3 system up to 70 GPa

Science.gov (United States)

Ohnishi, Satoka; Kuwayama, Yasuhiro; Inoue, Toru

2017-06-01

Melting experiments in a binary system MgO-MgSiO3 were performed up to 70 GPa using a CO2 laser heated diamond anvil cell. The quenched samples were polished and analyzed by a dualbeam focused ion beam (FIB) and a field emission scanning electron microscope (FE-SEM), respectively. The liquidus phase and the eutectic composition were determined on the basis of textual and chemical analyses of sample cross sections. Our experimental results show that the eutectic composition is the Si/Mg molar ratio of 0.76 at 35 GPa and it decreases with increasing pressure. Above 45 GPa, it becomes relatively constant at about 0.64-0.65 Si/Mg molar ratio. Using our experimental data collected at a wide pressure range up to 70 GPa together with previous experimental data, we have constructed a thermodynamic model of the eutectic composition of the MgO-MgSiO3 system. The eutectic composition extrapolated to the pressure and temperature conditions at the base of the mantle is about 0.64 Si/Mg molar ratio. The modeled eutectic composition is quite consistent with a previous prediction from ab initio calculations (de Koker et al. in Earth Planet Sci Lett 361:58-63, 2013), suggesting that the simple assumption of a non-ideal regular solution model can well describe the melting relation of the MgO-MgSiO3 system at high pressure. Our results show that the liquidus phase changes from MgO-periclase to MgSiO3-bridgmanite at 35 GPa for the simplified pyrolite composition ( 0.7 Si/Mg molar ratio), while MgSiO3-bridgmanite is the liquidus phase at the entire lower mantle conditions for the chondritic composition ( 0.84 Si/Mg molar ratio).

Effects of limestone, N, K and Mg fertilizers on Mg absorption by oats and barley

Energy Technology Data Exchange (ETDEWEB)

Alston, A M

1966-01-01

Oats grown in a pot experiment on two sandy loams were sampled at four stages of growth. Neither KCl nor MgSO/sub 4/. 7H/sub 2/O had any effect on yield but % Mg and total Mg uptake were consistently decreased by applying K and increased by applying Mg. Ca(NO/sub 3/)/sub 2/ increased % Mg more than did (NH/sub 4/)/sub 2/SO/sub 4/, but yield and total Mg uptake were higher where (NH/sub 4/)/sub 2/SO/sub 4/ was applied. The effects of fertilizers were similar on both soils. The effects of applying (NH/sub 4/)/sub 2/SO/sub 4/ and NaNO/sub 2/ to the soil on % Mg in barley were compared in a field experiment on an acid loam to which several rates of limestone had been applied. Treatments had no effect on the % Mg in grain or straw at maturity. At four earlier stages of growth (NH/sub 4/)/sub 2/SO)/sub 4/ increased % Mg in the plants more than did NaNO/sub 2/. Limestone slightly increased % Mg. Nitrification of NH/sub 4/ in the soil was rapid.

Influence of Ca/Mg ratio on phytoextraction properties of Salix viminalis. II. Secretion of low molecular weight organic acids to the rhizosphere.

Science.gov (United States)

Magdziak, Z; Kozlowska, M; Kaczmarek, Z; Mleczek, M; Chadzinikolau, T; Drzewiecka, K; Golinski, P

2011-01-01

A hydroponic experiment in a phytotron was performed to investigate the effect of two different Ca/Mg ratios (4:1 and 1:10) and trace element ions (Cd, Cu, Pb and Zn) in solution on the efficiency of low molecular weight organic acid (LMWOA) formation in Salix viminalis rhizosphere. Depending on the Ca/Mg ratio and presence of selected trace elements at 0.5mM concentration, the amount and kind of LMWOAs in the rhizosphere were significantly affected. In physiological 4:1 Ca/Mg ratio the following complex of acids was observed: malonic (Pb, Zn), citric, lactic, maleic and succinic (Zn) acids. Under 1:10 Ca/Mg ratio, citric (Cd, Zn), maleic and succinic (Cd, Cu, Pb, Zn) acids were seen. Additionally, high accumulation of zinc and copper in all systems was observed, with the exception of those where one of the metals was at higher concentration. Summing up, the results indicate a significant role of LMWOAs in Salix phytoremediation abilities. Both effects can be modulated depending on the mutual Ca/Mg ratio. Copyright © 2010 Elsevier Inc. All rights reserved.

Thin film interference optics for imaging the O II 834-A airglow

Science.gov (United States)

Seely, John F.; Hunter, William R.

1991-01-01

Normal incidence thin film interference mirrors and filters have been designed to image the O II 834-A airglow. It is shown that MgF2 is a useful spacer material for this wavelength region. The mirrors consist of thin layers of MgF2 in combination with other materials that are chosen to reflect efficiently in a narrow band centered at 834 A. Peak reflectance of 60 percent can be obtained with a passband 200 A wide. Al/MgF2/Si and Al/MgF2/SiC interference coatings have been designed to reflect 834 A and to absorb the intense H I 1216 A airglow. An In/MgF2/In interference filter is designed to transmit 834 A and attenuate 1216 A radiation. Interference photocathode coatings for rejecting 1216 A radiation are also discussed.

Effect of different seawater Mg

NARCIS (Netherlands)

Mewes, A.; Langer, G.; de Nooijer, L.J.; Bijma, J.; Reichart, G.J.

2014-01-01

Magnesium, incorporated in foraminiferal calcite (Mg/CaCC), is used intensively to reconstruct past seawater temperatures but, in addition to temperature, the Mg/CaCC of foraminiferal tests also depends on the ratio of Mg and Ca in seawater (Mg/CaSW). The physiological mechanisms responsible for

Sorption and reduction of selenite on chlorite surfaces in the presence of Fe(II) ions.

Science.gov (United States)

Baik, Min Hoon; Lee, Seung Yeop; Jeong, Jongtae

2013-12-01

The sorption and reduction of selenite on chlorite surfaces in the presence of Fe(II) ions were investigated as a function of pH, Se(IV) concentration, and Fe(II) concentration under an anoxic condition. The sorption of Se(IV) onto chlorite surfaces followed the Langmuir isotherm regardless of the presence of Fe(II) ions in the solution. The Se(IV) sorption was observed to be very low at all pH values when the solution was Fe(II)-free or the concentration of Fe(II) ions was as low as 0.5 mg/L. However, the Se(IV) sorption was enhanced at a pH > 6.5 when the Fe(II) concentration was higher than 5 mg/L because of the increased sorption of Fe(II) onto the chlorite surfaces. XANES (X-ray absorption near edge structure) spectra of the Se K-edge showed that most of the sorbed Se(IV) was reduced to Se(0) by Fe(II) sorbed onto the chlorite surfaces, especially at pH > 9. The combined results of field-emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) also showed that elemental selenium and goethite were formed and precipitated on the chlorite surfaces during the sorption of selenite. Consequently it can be concluded that Se(IV) can be reduced to Se(0) in the presence of Fe(II) ions by the surface catalytic oxidation of Fe(II) into Fe(III) and the formation of goethite at neutral and particularly alkaline conditions. Thus the mobility of selenite in groundwater is expected to be reduced by the presence of a relatively higher concentration of Fe(II) in subsurface environments. Copyright © 2013 Elsevier Ltd. All rights reserved.

Oral salmon calcitonin induced suppression of urinary collagen type II degradation in postmenopausal women: a new potential treatment of osteoarthritis.

Science.gov (United States)

Bagger, Yu Z; Tankó, László B; Alexandersen, Peter; Karsdal, Morten A; Olson, Melvin; Mindeholm, Linda; Azria, Moïse; Christiansen, Claus

2005-09-01

To assess the efficacy of 3 months of oral salmon calcitonin (sCT) on cartilage degradation as estimated by the changes in the urinary excretion of C-terminal telopeptide of collagen type II (CTX-II), and to investigate whether the response of oral sCT to urinary CTX-II depends on the baseline level of cartilage turnover. This was a randomized, double blind, placebo-controlled clinical setting including 152 Danish postmenopausal women aged 55-85. The subjects received treatment with the different doses of sCT (0.15, 0.4, 1.0, or 2.5 mg) combined with Eligen technology-based carrier molecule (200 mg), or placebo for 3 months. The efficacy parameter was the changes in the 24-h excretion of urinary CTX-I/II corrected for creatinine excretion at month 3. sCT induced a significant dose-dependent decrease in 24-h urinary CTX-II excretion. Similar dose-dependent responses were found in 24-h urinary CTX-I. When stratifying the study population into tertiles of baseline urinary CTX-II, the present osteoarthritic symptoms and definite cases of osteoarthritis (OA) were significantly more frequent in women in the highest tertile of CTX-II (mean 391 +/- 18 ng/mmol). Women who received 1.0 mg of sCT and had the highest cartilage turnover presented the greatest decrease in urinary CTX-II after 3 months of treatment. In addition to its pronounced effect on bone resorption, this novel oral sCT formulation may also reduce cartilage degradation and thereby provide therapeutic benefit in terms of chondroprotection. Women with high cartilage turnover are more likely to benefit from oral sCT treatment.

Decay of a Jπ=36+ Resonance in the 24Mg+24Mg Reaction

International Nuclear Information System (INIS)

Salsac, M.-D.; Haas, F.; Courtin, S.

2005-01-01

For the 24 Mg+ 24 Mg reaction, striking narrow and correlated resonance structures have been observed previously in the excitation functions of the elastic and low-lying channels. In our study we have decided to focus on the resonance at E C M =45.7 MeV, which is known to have J π =36 + . Despite the very high excitation energy(∼60 MeV) in the 48 Cr composite system, this resonance has a narrow total width of 170 keV. To determine precisely which states in the inelastic 24 Mg channels carry away the resonance flux, an experiment, on the 24 Mg + 24 Mg reaction at energies On and OFF resonance, has been performed at the Legnaro Tandem accelerator using the Prisma fragment spectrometer associated with the CLARA γ array

Mg-Ca Alloys Produced by Reduction of CaO: Understanding of ECO-Mg Alloy Production

Science.gov (United States)

Jung, In-Ho; Lee, Jin Kyu; Kim, Shae K.

2017-04-01

There have been long debates about the environment conscious (ECO) Mg technology which utilizes CaO to produce Ca-containing Mg alloys. Two key process technologies of the ECO-Mg process are the chemical reduction of CaO by liquid Mg and the maintenance of melt cleanliness during the alloying of Ca. Thermodynamic calculations using FactSage software were performed to explain these two key issues. In addition, an experimental study was performed to compare the melt cleanliness of the Ca-containing Mg alloys produced by the conventional route with metallic Ca and the ECO-Mg route with CaO.

Synthesis and characterisation of Cu(II), Ni(II), Mn(II), Zn(II) and VO(II ...

Indian Academy of Sciences (India)

Unknown

Synthesis and characterisation of Cu(II), Ni(II), Mn(II), Zn(II) and VO(II) Schiff base complexes derived from o-phenylenediamine and acetoacetanilide. N RAMAN*, Y PITCHAIKANI RAJA and A KULANDAISAMY. Department of Chemistry, VHNSN College, Virudhunagar 626 001, India e-mail: ra_man@123india.com.

Positron annihilation study of formation of Mg vacancy in MgO

International Nuclear Information System (INIS)

Mizuno, M.; Araki, H.; Shirai, Y.; Inoue, Y.; Sugita, K.; Mizoguchi, T.; Tanaka, I.; Adachi, H.

2004-01-01

We have investigated the formation of Mg vacancy induced by ultra-dilute trivalent impurities in MgO by a combination of positron annihilation measurement and theoretical calculations of positron lifetimes. The undoped MgO yields the shortest positron lifetime of 130 ps that is shorter than that of 166 ps previously reported using a single crystal sample. The positron lifetime of the doped samples increases with the increase of the Al or Ga dopant concentration and is saturated at around 170 ps. This result indicates that the previously reported value of 166 ps is ascribed to not the bulk but the vacancy state induced by impurities. The experimental bulk lifetime of 130 ps, which is obtained by employing trapping model, is well reproduced by the theoretical calculation using the semiconductor model. The calculated defect lifetime is about 20 ps longer than the experimental value. This may be due to the lattice relaxation around Mg vacancy associated with the trapping of positrons. (orig.)

Positron annihilation study of formation of Mg vacancy in MgO

Energy Technology Data Exchange (ETDEWEB)

Mizuno, M.; Araki, H.; Shirai, Y. [Science and Technology Center for Atoms, Molecules and Ions Control, Osaka Univ., Osaka (Japan); Inoue, Y.; Sugita, K. [Dept. of Materials Science and Engineering, Osaka Univ., Osaka (Japan); Mizoguchi, T.; Tanaka, I.; Adachi, H. [Dept. of Materials Science and Engineering, Kyoto Univ., Kyoto (Japan)

2004-07-01

We have investigated the formation of Mg vacancy induced by ultra-dilute trivalent impurities in MgO by a combination of positron annihilation measurement and theoretical calculations of positron lifetimes. The undoped MgO yields the shortest positron lifetime of 130 ps that is shorter than that of 166 ps previously reported using a single crystal sample. The positron lifetime of the doped samples increases with the increase of the Al or Ga dopant concentration and is saturated at around 170 ps. This result indicates that the previously reported value of 166 ps is ascribed to not the bulk but the vacancy state induced by impurities. The experimental bulk lifetime of 130 ps, which is obtained by employing trapping model, is well reproduced by the theoretical calculation using the semiconductor model. The calculated defect lifetime is about 20 ps longer than the experimental value. This may be due to the lattice relaxation around Mg vacancy associated with the trapping of positrons. (orig.)

Sonochemical synthesis and photocatalytic property of zinc oxide nanoparticles doped with magnesium(II)

International Nuclear Information System (INIS)

Lu, Xianyong; Liu, Zhaoyue; Zhu, Ying; Jiang, Lei

2011-01-01

Highlights: → Mg-doped ZnO nanoparticles were synthesized by sonochemical strategy. → Mg-doped ZnO nanoparticles present good photocatalytic properties. → The change of band gap contributes to their high efficiency in photocatalyst. -- Abstract: Mg-doped ZnO nanoparticles were successfully synthesized by sonochemical method. The products were characterized by scan electron microscopy (SEM) and X-ray powder diffraction (XRD). SEM images revealed that ZnO doped with Mg(II) nanoparticles and ZnO nanoparticles synthesized by the same strategy all had spherical topography. XRD patterns showed that the doped nanoparticles had the same crystals structures as the pure ZnO nanoparticles. The Mg-doped ZnO nanoparticles had larger lattice volume than the un-doped nanoparticles. X-ray photoelectron spectroscopy (XPS) not only demonstrated the moral ratio of Mg and Zn element on the surface of nanoparticles, but their valence in nanoparticles as well. The Mg-doped ZnO nanoparticles presented good properties in photocatalyst compared with pure ZnO nanoparticles.

Recombinant hemoglobin II from Lucina pectinata: a large-scale method for hemeprotein expression in E. coli.

Science.gov (United States)

Ramos, Cacimar; Pietri, Ruth; Lorenzo, Wilmarie; Roman, Elddie; Granell, Laura B; Cadilla, Carmen L; López-Garriga, Juan

2010-02-01

Hemoglobin II from the clam L. pectinata is an O(2) reactive protein that remains oxygenated in the presence of other molecules. To determine the mechanism of ligand selection in this hemoglobin, rHbII was expressed in large quantities using an improved fermentation process. The highest protein yield was obtained by: transforming HbII into the BLi5 cells, inducing and supplementing the culture during the mid-log phase with 1 mM IPTG, 30 microg/mL hemin chloride and 1% glucose, and decreasing the temperature to 30 degrees C after induction. In addition, cell culture density was greatly enhanced by using glycerol, adding MgSO(4), supplementing the media with glucose after the glycerol was consumed and maintaining the dissolved oxygen at 35%. Under these conditions the maximum protein yield obtained was approximately 2,300 mg/L. The results indicate that rHbII is similar to the native protein. The protocol was validated with other hemoglobins, indicating that it can be extended to other hemeproteins.

Biologically active new Fe(II, Co(II, Ni(II, Cu(II, Zn(II and Cd(II complexes of N-(2-thienylmethylenemethanamine

Directory of Open Access Journals (Sweden)

C. SPÎNU

2008-04-01

Full Text Available Iron(II, cobalt(II, nickel (II, copper (II, zinc(II and cadmium(II complexes of the type ML2Cl2, where M is a metal and L is the Schiff base N-(2-thienylmethylenemethanamine (TNAM formed by the condensation of 2-thiophenecarboxaldehyde and methylamine, were prepared and characterized by elemental analysis as well as magnetic and spectroscopic measurements. The elemental analyses suggest the stoichiometry to be 1:2 (metal:ligand. Magnetic susceptibility data coupled with electronic, ESR and Mössbauer spectra suggest a distorted octahedral structure for the Fe(II, Co(II and Ni(II complexes, a square-planar geometry for the Cu(II compound and a tetrahedral geometry for the Zn(II and Cd(II complexes. The infrared and NMR spectra of the complexes agree with co-ordination to the central metal atom through nitrogen and sulphur atoms. Conductance measurements suggest the non-electrolytic nature of the complexes, except for the Cu(II, Zn(II and Cd(II complexes, which are 1:2 electrolytes. The Schiff base and its metal chelates were screened for their biological activity against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa and the metal chelates were found to possess better antibacterial activity than that of the uncomplexed Schiff base.

Synthesis of Mg(OH)2, MgO, and Mg nanoparticles using laser ablation of magnesium in water and solvents

Energy Technology Data Exchange (ETDEWEB)

Tran, P.X.; Howard, B.H.; Martello, D.V.; Soong, Y.; Chyu, M.K.

2008-01-01

laser ablation of magnesium in deionized water (OW), solutions of OW and sodium dodecyl sulfate (50S) with different concentrations, acetone and 2-propanol has been conducted, The results showed that ablation in acetone and 2-propanol yielded MgO and Mg nanocrystallites as isolated particles and agglomerated chains probably intermixed with organic residues resulting from the alterationj decomposition of the solvents under the high-energy conditions. Brucite-like Mg(OH)2 particles were mainly produced by laser ablation of Mg in either OW or OW~SOS solutions. Ablation in OW yielded particles of fiber-like shapes having a diameter of about 5-lOnm and length as long as 150nm. Materials produced in DW-SOS solutions were composed of various size and shape particles, Some had rough surfaces with irregular shapes. Small particles were about 20-30nm and larger particles were about 120 nm. Particles with rod-like, triangular, and plate-like shapes were also observed.

Synthesis of Mg(OH) 2, MgO, and Mg nanoparticles using laser ablation of magnesium in water and solvents

Science.gov (United States)

Phuoc, Tran X.; Howard, Bret. H.; Martello, Donald V.; Soong, Yee; Chyu, Minking K.

2008-11-01

Laser ablation of magnesium in deionized water (DW), solutions of DW and sodium dodecyl sulfate (SDS) with different concentrations, acetone and 2-propanol has been conducted. The results showed that ablation in acetone and 2-propanol yielded MgO and Mg nanocrystallites as isolated particles and agglomerated chains probably intermixed with organic residues resulting from the alteration/decomposition of the solvents under the high-energy conditions. Brucite-like Mg(OH) 2 particles were mainly produced by laser ablation of Mg in either DW or DW-SDS solutions. Ablation in DW yielded particles of fiber-like shapes having a diameter of about 5-10 nm and length as long as 150 nm. Materials produced in DW-SDS solutions were composed of various size and shape particles. Some had rough surfaces with irregular shapes. Small particles were about 20-30 nm and larger particles were about 120 nm. Particles with rod-like, triangular, and plate-like shapes were also observed.

Administração inadvertida de 4 mg de morfina por via subaracnóidea: relato de caso Administración inadvertida de 4 mg de morfina por vía subaracnoidea: relato de caso Accidental subarachnoid administration of 4 mg of morphine: case report

Directory of Open Access Journals (Sweden)

Bruno Salomé de Morais

2008-04-01

Full Text Available JUSTIFICATIVA E OBJETIVOS: A administração de morfina por via subaracnóidea é técnica bem estabelecida para analgesia pós-operatória devido a sua eficácia, segurança e baixo custo. A administração inadvertida de 4 mg de morfina por via subaracnóidea complicada por fibrilação atrial ap��s administração de naloxona foi o objetivo desse relato. RELATO DO CASO: Paciente do sexo masculino, 45 anos, 75 kg, 1,72 m, estado físico ASA II, hipertenso, a ser submetido à reconstrução do ligamento cruzado anterior do joelho esquerdo. Após a realização da raquianestesia, foi constatada troca da ampola de morfina, com administração de 4 mg (0,4 mL da ampola de 10 mg por via subaracnóidea. A freqüência respiratória oscilou entre 12 e 16 incursões respiratórias por minuto e o paciente manteve-se estável hemodinamicamente sem queixas no intra-operatório. Após 30 minutos da admissão na SRPA, apresentou vômitos e sudorese, tratados com 0,4 mg de naloxona seguidos de infusão contínua de 0,2 mg.h-1 até o desaparecimento dos sintomas. A infusão contínua de naloxona foi mantida na Unidade de Terapia Intensiva (UTI, onde a pressão arterial, freqüência cardíaca, freqüência respiratória, saturação de oxigênio foram monitoradas, assim como a presença de náusea, prurido, vômito, sedação, dor e retenção urinária observadas. Após 2 horas de admissão na UTI, o paciente apresentou fibrilação atrial aguda sem instabilidade hemodinâmica. O ritmo sinusal foi restabelecido após 150 mg de amiodarona e interrupção da infusão de naloxona. Nas 18 horas seguintes apresentou estabilidade hemodinâmica e evoluiu sem outras intercorrências até a alta hospitalar. CONCLUSÕES: O presente relato alerta para o risco de troca de medicamentos durante o ato anestésico e ressalta a importância do encaminhamento dos pacientes em tratamento de sobredose de opióides à UTI em virtude de seus potenciais efeitos adversos

Antibacterial biodegradable Mg-Ag alloys

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D Tie

2013-06-01

Full Text Available The use of magnesium alloys as degradable metals for biomedical applications is a topic of ongoing research and the demand for multifunctional materials is increasing. Hence, binary Mg-Ag alloys were designed as implant materials to combine the favourable properties of magnesium with the well-known antibacterial property of silver. In this study, three Mg-Ag alloys, Mg2Ag, Mg4Ag and Mg6Ag that contain 1.87 %, 3.82 % and 6.00 % silver by weight, respectively, were cast and processed with solution (T4 and aging (T6 heat treatment.The metallurgical analysis and phase identification showed that all alloys contained Mg4Ag as the dominant β phase. After heat treatment, the mechanical properties of all Mg-Ag alloys were significantly improved and the corrosion rate was also significantly reduced, due to presence of silver. Mg(OH2 and MgO present the main magnesium corrosion products, while AgCl was found as the corresponding primary silver corrosion product. Immersion tests, under cell culture conditions, demonstrated that the silver content did not significantly shift the pH and magnesium ion release. In vitro tests, with both primary osteoblasts and cell lines (MG63, RAW 264.7, revealed that Mg-Ag alloys show negligible cytotoxicity and sound cytocompatibility. Antibacterial assays, performed in a dynamic bioreactor system, proved that the alloys reduce the viability of two common pathogenic bacteria, Staphylococcus aureus (DSMZ 20231 and Staphylococcus epidermidis (DSMZ 3269, and the results showed that the killing rate of the alloys against tested bacteria exceeded 90%. In summary, biodegradable Mg-Ag alloys are cytocompatible materials with adjustable mechanical and corrosion properties and show promising antibacterial activity, which indicates their potential as antibacterial biodegradable implant materials.

Hydrodechlorination of Tetrachloromethane over Palladium Catalysts Supported on Mixed MgF2-MgO Carriers

Directory of Open Access Journals (Sweden)

Magdalena Bonarowska

2016-11-01

Full Text Available Pd/MgO, Pd/MgF2 and Pd/MgO-MgF2 catalysts were investigated in the reaction of CCl4 hydrodechlorination. All the catalysts deactivated in time on stream, but the degree of deactivation varied from catalyst to catalyst. The MgF2-supported palladium with relatively large metal particles appeared the best catalyst, characterized by good activity and selectivity to C2-C5 hydrocarbons. Investigation of post-reaction catalyst samples allowed to find several details associated with the working state of hydrodechlorination catalysts. The role of support acidity was quite complex. On the one hand, a definite, although not very high Lewis acidity of MgF2 is beneficial for shaping high activity of palladium catalysts. The MgO-MgF2 support characterized by stronger Lewis acidity than MgF2 contributes to very good catalytic activity for a relatively long reaction period (~5 h but subsequent neutralization of stronger acid centers (by coking eliminates them from the catalyst. On the other hand, the role of acidity evolution, which takes place when basic supports (like MgO are chlorided during HdCl reactions, is difficult to assess because different events associated with distribution of chlorided support species, leading to partial or even full blocking of the surface of palladium, which plays the role of active component in HdCl reactions.

Distinct angiotensin II receptor in primary cultures of glial cells from rat brain

International Nuclear Information System (INIS)

Raizada, M.K.; Phillips, M.I.; Crews, F.T.; Sumners, C.

1987-01-01

Angiotensin II (Ang-II) has profound effects on the brain. Receptors for Ang-II have been demonstrated on neurons, but no relationship between glial cells and Agn-II has been established. Glial cells (from the hypothalamus and brain stem of 1-day-old rat brains) in primary culture have been used to demonstrate the presence of specific Ang-II receptors. Binding of 125 I-Ang-II to glial cultures was rapid, reversible, saturable, and specific for Ang-II. The rank order of potency of 125 I-Ang-II binding was determined. Scatchard analysis revealed a homogeneous population of high-affinity binding sites with a B/sub max/ of 110 fmol/mg of protein. Light-microscopic autoradiography of 125 I-Ang-II binding supported the kinetic data, documenting specific Ang-II receptors on the glial cells. Ang-II stimulated a dose-dependent hydrolysis of phosphatidylinositols in glial cells, an effect mediated by Ang-II receptors. However, Ang-II failed to influence [ 3 H] norepinephrine uptake, and catecholamines failed to regulate Ang-II receptors, effects that occur in neurons. These observations demonstrate the presence of specific Ang-II receptors on the glial cells in primary cultures derived from normotensive rat brain. The receptors are kinetically similar to, but functionally distinct from, the neuronal Ang-II receptors

Electrical transport in n-type ZnMgSSe grown by molecular beam epitaxy on GaAs

International Nuclear Information System (INIS)

Marshall, T.; Petruzzello, J.A.; Herko, S.P.

1994-01-01

Significant progress in improving the Performance of blue-green II-VI semiconductor injection lasers has come about from advances in the epitaxial growth and doping of ZnMgSSe on GaAs substrates. This paper investigates electrical transport and its relation to structural quality in n-type Zn 1-y Mg y S x Se 1-x epilayers doped with Cl, grown by molecular beam epitaxy. The composition parameters x and y vary from about 0.12-0.18 and 0.08-0.15, respectively. The quaternary epilayers studied are lattice-matched (or nearly so) to the GaAs substrate. Temperature-dependent Hall-effect measurements are performed on seven n-type ZnMgSSe:Cl epilayers, and a technique is presented whereby the resulting mobility-vs-temperature data is compared with data for ZnSe to obtain a structural figure of merit that is useful in characterizing the quaternary epilayer. 29 refs., 4 figs

Intrinsic Conductivity in Magnesium-Oxygen Battery Discharge Products: MgO and MgO2

DEFF Research Database (Denmark)

Smith, Jeffrey G.; Naruse, Junichi; Hiramatsu, Hidehiko

2017-01-01

Nonaqueous magnesium–oxygen (or “Mg-air”) batteries are attractive next generation energy storage devices due to their high theoretical energy densities, projected low cost, and potential for rechargeability. Prior experiments identified magnesium oxide, MgO, and magnesium peroxide, MgO2...

Corrosion analysis of AlMg2 and AlMgSi using electrochemical method

International Nuclear Information System (INIS)

Dian A; Maman Kartaman; Rosika K; Yanlinastuti

2014-01-01

Corrosion test of cladding materials and structures of research reactor fuel, AlMgSi and AlMg2 have been performed in demineralized water of pH 2 and 6.7 using an electrochemical method. Corrosion phenomenon is affected by several factor such as composition and condition of solution. The purpose of this activity is to investigate the corrosion phenomena through the determination of the parameters of corrosion and polarization curve. The materials used are AlMg2 and AlMgSi alloy in circular dish shape with an area of 1 Cm"2. Preparation of the test sample is performed through several stages polishing, cleaning and drying procedures followed ASTM G3. The electrochemical method is done by measuring the open circuit potential (OCP), polarization resistance and potentiodynamic in demineralized water of pH 2 and pH 6.7 at temperature of 25°C. The results of the OCP is the corrosion potential (Ecorr) of AlMg2 and AlMgSi each of -906.1 mV and -619.8 mV at pH 2 and -868.6 and -756.7 mV at pH 6.7 mV. The results of measurements by polarization resistance technique showed that the corrosion rate of AlMg2 and AlMgSi in safe category (<2 mpy) at pH 6.7 and at pH 2 corrosion rate increased significantly, but still in the lightweight category (<20 mpy). Potentiodynamic curves showed that the passivation at pH 6.7 is very low while the passivation at pH 2 occurs within a relatively short range potential and followed events corroded. (author)

Presentation - I: Electronic structure calculations of ordered cubic-based Mg-Li alloys; II: Microstructural evolution of a+ß

CSIR Research Space (South Africa)

Phasha, MJ

2006-04-01

Full Text Available Mg alloys have, in the past decade, received revolutionary attention which emanated from the need of lightweight materials in transportation and allied industries, wherein intrinsic strength to weight ratio is of paramount importance...

Inhibition of the 26S proteasome blocks progesterone receptor-dependent transcription through failed recruitment of RNA polymerase II.

Science.gov (United States)

Dennis, Andrew P; Lonard, David M; Nawaz, Zafar; O'Malley, Bert W

2005-03-01

In the present study, we investigated the involvement of protein degradation via the 26S proteasome during progesterone receptor (PR)-mediated transcription in T-47D cells containing a stably integrated MMTV-CAT reporter construct (CAT0 cells). Progesterone induced CAT and HSD11beta2 transcription while co-treatment with the proteasome inhibitor, MG132, blocked PR-induced transcription in a time-dependent fashion. MG132 treatment also inhibited transcription of beta-actin and cyclophilin, but not two proteasome subunit genes, PSMA1 and PSMC1, indicating that proteasome inhibition affects a subset of RNA polymerase II (RNAP(II))-regulated genes. Progesterone-mediated recruitment of RNAP(II) was blocked by MG132 treatment at time points later than 1 h that was not dependent on the continued presence of PR, associated cofactors, and components of the general transcription machinery, supporting the concept that proteasome-mediated degradation is needed for continued transcription. Surprisingly, progesterone-mediated acetylation of histone H4 was inhibited by MG132 with the concomitant recruitment of HDAC3, NCoR, and SMRT. We demonstrate that the steady-state protein levels of SMRT and NCoR are higher in the presence of MG132 in CAT0 cells, consistent with other reports that SMRT and NCoR are targets of the 26S proteasome. However, inhibition of histone deacetylation by trichostatin A (TSA) treatment or SMRT/NCoR knockdown by siRNA did not restore MG132-inhibited progesterone-dependent transcription. Therefore, events other than histone deacetylation and stability of SMRT and NCoR must also play a role in inhibition of PR-mediated transcription.

Application of Local Adsorbant From Southeast Sulawesi Clay Immobilized Saccharomyces Cerevisiae Bread’s Yeast Biomass for Adsorption Of Mn(Ii) Metal Ion

Science.gov (United States)

R, Halimahtussaddiyah; Mashuni; Budiarni

2017-05-01

Southeast Sulawesi has a great stock of clay. It is probably to use as a source of adsorbent. The adsorbent capacity of clay can be largered with teratment using bread’s yeast as biomass. At this research, study of analysis adsorption of Mn(II) metal ion on clay immobilized Saccharomyces cerevisiae bread’s yeast biomass adsorbent has been conducted. The aims of this research were to determine the effects of contact time, pH and concentration of Mn(II) metal ion and to determine the adsorption capacity of clay immobilized S. cerevisiae biomass for adsorbtion of Mn(II) metal ion. Activated clay was synthesized by reaction of clay with KMnO4, H2SO4 and HCl. S. cerevisiae biomass was result by bread’s yeast mashed. Immobilization of S. cerevisiae biomass into clay was done by mixing of ratio of S. cerevisiae bread’s yeast biomass and clay equal to 1:3 (mass of biomassa : mass of clay). The adsorption capacity was determined by using Freundlich and Langmuir adsorption isoterms. The results of FTIR spectrums showed that the functional groups of clay immobilized S. cerevisiae biomass were Si-OH (wave number 1643 cm-1), Si-O-Si (wave number 1033 cm-1), N-H (wave number 2337 cm-1), O-H (wave number 3441cm-1), and C-H (wave number 2931 cm-1). The result of adsorption capacity from Mn(II) metal ion of contact time optimum 120 minutes, pH optimun at 7 and concentration optimum 50 mg/L were 1,816 mg/g; 0,509 mg/g and 2,624mg/g respectively. The adsorption capacity of Mn(II) metal ion with ratio 1:3 (biomass : clay) was 0,1045 mg/g. Type of isothermal adsorption followed the Freunlich adsorption.

Transport, fate, and stimulating impact of silver nanoparticles on the removal of Cd(II) by Phanerochaete chrysosporium in aqueous solutions

International Nuclear Information System (INIS)

Zuo, Yanan; Chen, Guiqiu; Zeng, Guangming; Li, Zhongwu; Yan, Ming; Chen, Anwei; Guo, Zhi; Huang, Zhenzhen; Tan, Qiong

2015-01-01

Highlights: • Appropriate concentration of AgNPs can stimulate the biological removal of Cd(II). • Added AgNPs were oxidatively dissolved and transported to the surface of fungus. • AgNPs have undergone coarsening in the process of transport. • Amino, carboxyl, hydroxyl, and other reducing groups were involved in transportion. - Abstract: Despite the knowledge about increasing discharge of silver nanoparticles (AgNPs) into wastewater and its potential toxicity to microorganisms, the interaction of AgNPs with heavy metals in the biological removal process remains poorly understood. This study focused on the effect of AgNPs (hydrodynamic diameter about 24.3 ± 0.37 nm) on the removal of cadmium (Cd(II)) by using a model white rot fungus species, Phanerochaete chrysosporium. Results showed that the biological removal capacity of Cd(II) increased with the concentration of AgNPs increasing from 0.1 mg/L to 1 mg/L. The maximum removal capacity (4.67 mg/g) was located at 1 mg/L AgNPs, and then decreased with further increasing AgNPs concentration, suggesting that an appropriate concentration of AgNPs has a stimulating effect on the removal of Cd(II) by P. chrysosporium instead of an inhibitory effect. Results of Ag + and total Ag concentrations in the solutions together with those of SEM and XRD demonstrated that added AgNPs had undergone oxidative dissolution and transported from the solution to the surface of fungal mycelia (up to 94%). FTIR spectra confirmed that amino, carboxyl, hydroxyl, and other reducing functional groups were involved in Cd(II) removal, AgNPs transportation, and the reduction of Ag + to AgNPs

Transport, fate, and stimulating impact of silver nanoparticles on the removal of Cd(II) by Phanerochaete chrysosporium in aqueous solutions

Energy Technology Data Exchange (ETDEWEB)

Zuo, Yanan [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Chen, Guiqiu, E-mail: gqchen@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Zeng, Guangming, E-mail: zgming@hnu.edu.cn [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Li, Zhongwu; Yan, Ming [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China); Chen, Anwei [College of Resources and Environment, Hunan Agricultural University, Changsha 410128 (China); Guo, Zhi; Huang, Zhenzhen; Tan, Qiong [College of Environmental Science and Engineering, Hunan University, Changsha 410082 (China); Key Laboratory of Environmental Biology and Pollution Control (Hunan University), Ministry of Education, Changsha 410082 (China)

2015-03-21

Highlights: • Appropriate concentration of AgNPs can stimulate the biological removal of Cd(II). • Added AgNPs were oxidatively dissolved and transported to the surface of fungus. • AgNPs have undergone coarsening in the process of transport. • Amino, carboxyl, hydroxyl, and other reducing groups were involved in transportion. - Abstract: Despite the knowledge about increasing discharge of silver nanoparticles (AgNPs) into wastewater and its potential toxicity to microorganisms, the interaction of AgNPs with heavy metals in the biological removal process remains poorly understood. This study focused on the effect of AgNPs (hydrodynamic diameter about 24.3 ± 0.37 nm) on the removal of cadmium (Cd(II)) by using a model white rot fungus species, Phanerochaete chrysosporium. Results showed that the biological removal capacity of Cd(II) increased with the concentration of AgNPs increasing from 0.1 mg/L to 1 mg/L. The maximum removal capacity (4.67 mg/g) was located at 1 mg/L AgNPs, and then decreased with further increasing AgNPs concentration, suggesting that an appropriate concentration of AgNPs has a stimulating effect on the removal of Cd(II) by P. chrysosporium instead of an inhibitory effect. Results of Ag{sup +} and total Ag concentrations in the solutions together with those of SEM and XRD demonstrated that added AgNPs had undergone oxidative dissolution and transported from the solution to the surface of fungal mycelia (up to 94%). FTIR spectra confirmed that amino, carboxyl, hydroxyl, and other reducing functional groups were involved in Cd(II) removal, AgNPs transportation, and the reduction of Ag{sup +} to AgNPs.

Complexes of cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II) and dioxouranium(II) with thiophene-2-aldehydethiosemicarbazone

International Nuclear Information System (INIS)

Singh, Balwan; Misra, Harihar

1986-01-01

Metal complexes of thiosemicarbazides have been known for their pharmacological applications. Significant antitubercular, fungicidal and antiviral activities have been reported for thiosemicarbazides and their derivatives. The present study describes the systhesis and characterisation of complexes of Co II , Cu II , Zn II ,Cd II and UO II with thiosemicarbazone obtained by condensing thiophene-2-aldehyde with thiosemicarbazide. 17 refs., 2 tables. (author)

Equilibrium, thermodynamic and kinetic studies on biosorption of Mn(II) from aqueous solution by Pseudomonas sp., Staphylococcus xylosus and Blakeslea trispora cells

International Nuclear Information System (INIS)

Gialamouidis, D.; Mitrakas, M.; Liakopoulou-Kyriakides, M.

2010-01-01

Biosorption of Mn(II) from aqueous solutions using Pseudomonas sp., Staphylococcus xylosus and Blakeslea trispora cells was investigated under various experimental conditions of pH, biomass concentration, contact time and temperature. The optimum pH value was determined to 6.0 and the optimum biomass concentration to 1.0 g L -1 for all types of cells. Mn(II) biosorption was found to fit better to the Langmuir model for Pseudomonas sp. and B. trispora and to Freundlich model for S. xylosus. Langmuir model gave maximum Mn(II) uptake capacity 109 mg g -1 for Pseudomonas sp. and much lower, 59 mg g -1 and 40 mg g -1 for S. xylosus and B. trispora, respectively. Pseudo-second-order kinetic model was also found to be in good agreement with the experimental results. Thermodynamic parameters of the adsorption confirmed the endothermic nature of sorption process with positive heat of enthalpy, accompanied by a positive value of entropy change. Interestingly, desorption experiments by treating biomass with 0.1 M HNO 3 solution resulted to more than 88% recovery of the adsorbed Mn(II) from Pseudomonas sp. and almost 95% and 99% from S. xylosus and B. trispora cells respectively, thus indicating that Mn(II) can be easily and quantitatively recovered from biomass.

Constraints on the ^22Ne(α,n)^25Mg reaction rate from ^natMg+n Total and ^25Mg(n,γ ) Cross Sections

Science.gov (United States)

Koehler, Paul

2002-10-01

The ^22Ne(α,n)^25Mg reaction is the neutron source during the s process in massive and intermediate mass stars as well as a secondary neutron source during the s process in low mass stars. Therefore, an accurate determination of this rate is important for a better understanding of the origin of nuclides heavier than iron as well as for improving s-process models. Also, because the s process produces seed nuclides for a later p process in massive stars, an accurate value for this rate is important for a better understanding of the p process. Because the lowest observed resonance in direct ^22Ne(α,n)^25Mg measurements is considerably above the most important energy range for s-process temperatures, the uncertainty in this rate is dominated by the poorly known properties of states in ^26Mg between this resonance and threshold. Neutron measurements can observe these states with much better sensitivity and determine their parameters much more accurately than direct ^22Ne(α,n)^25Mg measurements. I have analyzed previously reported Mg+n total and ^25Mg(n,γ ) cross sections to obtain a much improved set of resonance parameters for states in ^26Mg in this region, and an improved estimate of the uncertainty in the ^22Ne(α,n)^25Mg reaction rate. This work was supported by the U.S. DOE under contract No. DE-AC05-00OR22725 with UT-Battell, LLC.

Phase II study of Gleevec® plus hydroxyurea (HU) in adults with progressive or recurrent meningioma

OpenAIRE

Reardon, David A.; Norden, Andrew D.; Desjardins, Annick; Vredenburgh, James J.; Herndon, James E.; Coan, April; Sampson, John H.; Gururangan, Sridharan; Peters, Katherine B.; McLendon, Roger E.; Norfleet, Julie A.; Lipp, Eric S.; Drappatz, Jan; Wen, Patrick Y.; Friedman, Henry S.

2011-01-01

We prospectively evaluated the efficacy and safety of imatinib plus hydroxyurea in patients with progressive/recurrent meningioma. A total of 21 patients with progressive/recurrent meningioma were enrolled in this dual center, single-arm, phase II trial. All patients received 500 mg of hydroxyurea twice a day. Imatinib was administered at 400 mg/day for patients not on CYP3A enzyme inducing anti-epileptic drugs (EIAEDs) and at 500 mg twice a day for patients on EIAEDs. The primary endpoint wa...

Corrosion behaviour of Mg-Cu and Mg-Mo composites in 3.5% NaCl

International Nuclear Information System (INIS)

Budruk Abhijeet, S.; Balasubramaniam, R.; Gupta, M.

2008-01-01

The corrosion behaviour of pure magnesium, Mg-Cu (0.3, 0.6, and 1 vol.%) and Mg-Mo (0.1, 0.3, and 0.6 vol.%) composites has been studied in 3.5% NaCl solution by weight loss and polarisation methods. Corrosion rates determined by weight loss method were considerably higher than that determined by polarisation method. The corrosion rate increased with increasing volume fraction of reinforcement in Mg-Cu and Mg-Mo composites. At the same volume fraction of reinforcement, molybdenum reinforced composite corroded faster than copper reinforced composite. The galvanic current density between Mg-Cu and Mg-Mo couples has been experimentally measured using zero resistance ammeter technique. The experimentally observed galvanic current densities were in close agreement with those obtained using mixed potential theory analysis. SEM observation of corroded samples confirmed microgalvanic activity at the matrix/reinforcement interfaces. The poor corrosion resistance of composites has been attributed to microgalvanic effects between the matrix and reinforcements and inferior quality of surface films

Influence of microstructure on the formability of Al-Mg6.8 alloy

Directory of Open Access Journals (Sweden)

Minov Boris G.

2008-01-01

Full Text Available Formability of Al-Mg6.8 alloy has been evaluated experimentally in uniaxial tension and biaxial stretching. Three different structures developed after cold rolling and annealing in the range of temperature from 265 to 320 °C: (I recovered dual (a + β phase, (II recrystallized (a + β dual phase, and (III recrystallized a-Al single phase structure, were tested. Samples with recovered structure have shown a lower formability level than the samples with fully recrystallized structure. Formability level assessed through FLD and LDH value, has been a result of complex interaction between work hardening ability and strain rate sensitivity.

Structural and electronic properties of Mg and Mg-Nb co-doped TiO2 (101) anatase surface

International Nuclear Information System (INIS)

Sasani, Alireza; Baktash, Ardeshir; Mirabbaszadeh, Kavoos; Khoshnevisan, Bahram

2016-01-01

Highlights: • Formation energy of Mg and Mg-Nb co-doped TiO_2 anatase surface (101) is studied. • Effect of Mg defect to the TiO_2 anatase (101) surface and bond length distribution of the surface is studied and it is shown that Mg defects tend to stay far from each other. • Effect of Mg and Nb to the bond length distribution of the surface studied and it is shown that these defects tend to stay close to each other. • Effects of Mg and Mg-Nb defects on DSSCs using TiO_2 anatase hosting these defects are studied. - Abstract: In this paper, by using density functional theory, Mg and Nb-Mg co-doping of TiO_2 anatase (101) surfaces are studied. By studying the formation energy of the defects and the bond length distribution of the surface, it is shown that Mg defects tend to stay as far as possible to induce least possible lattice distortion while Nb and Mg defects stay close to each other to cause less stress to the surface. By investigating band structure of the surface and changes stemmed from the defects, potential effects of Mg and Mg-Nb co-doping of TiO_2 surface on dye-sensitized solar cells are investigated. In this study, it is shown that the Nb-Mg co-doping could increase J_S_C of the surface while slightly decreasing V_O_C compared to Mg doped surface, which might result in an increase in efficiency of the DSSCs compared to Nb or Mg doped surfaces.

The structural, electrical and optical properties of Mg-doped ZnO with different interstitial Mg concentration

Energy Technology Data Exchange (ETDEWEB)

Hu, Yonghong, E-mail: hchyh@njust.edu.cn [School of Nuclear Technology and Chemistry & Biology, Hubei University of Science and Technology, Xianning 437100 (China); Institute of Optoelectronics & Nanomaterials, College of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Zeng, Haibo [Institute of Optoelectronics & Nanomaterials, College of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China); Du, Jifu [School of Nuclear Technology and Chemistry & Biology, Hubei University of Science and Technology, Xianning 437100 (China); Hu, Ziyu [Beijing Computational Science Research Center, Beijing 100084 (China); Zhang, Shengli [Institute of Optoelectronics & Nanomaterials, College of Materials Science and Engineering, Nanjing University of Science and Technology, Nanjing 210094 (China)

2016-10-01

Through first principle calculations, we studied the structural, electronic and optical properties of ZnO doped by interstitial Mg. With the increase of Mg content (x), the derivations of lattice parameters from the wurtzite ZnO become more and more significant. The Mg-doped ZnO with x below 15.79% is found to be n-type semiconductor. The minimum of energy band gap and light transmittance in high energy region (7.5–25 eV) decrease while the conductivity and refractive index increase with increasing x. Further increasing x up to 20%, the Mg-doped ZnO is found to be direct-band-gap semiconductor with great structural derivation from wurtzite phase. The light transmittance increases while the refractive index decreases with the increase of x due to the change of geometry and electronic structure. So, it’s concluded that the electronic and optical properties of ZnO doped by interstitial Mg may be greatly influenced by Mg content. - Graphical abstract: The minimum of energy gap decreases while the corresponding relative number of electrons into the conduction bands increases when the interstitial Mg content x in Mg-doped ZnO increases (0 ≤ x ≤ 15.79%). - Highlights: • The energy band gap decreases with the increase of interstitial Mg content from 5.88% to 15.79%. • The conductivity increases with the increase of interstitial Mg content from 5.88% to 15.79%. • The Mg{sub x}Zn{sub 1-x}O (interstitial Mg content x= 20%) is found to be a direct-band-gap semiconductor. • The light transmittance decreases with the increase of interstitial Mg content from 5.88% to 15.79%. • The refractive index increases with the increase of interstitial Mg content from 5.88% to 15.79%.

Phase diagrams of aluminium alloys of Al-Cu-Mg, Al-Mg-Si-Cu, and Al-Mg-Li system

International Nuclear Information System (INIS)

Ber, L.B.; Kaputkin, E.Ya.

2001-01-01

Isothermal diagrams of phase transformations (DPT) and temperature-time charts (TTC) of variation of electric conductivity and of mechanical features at tension were plotted following thermal treatment according to the pattern of direct hardening and ageing and according to the pattern of normal aging for D16 commercial alloy, Al-Cu-Mg model alloy of the same system, AD37 commercial alloys of Al-Mg-Si-Cu and 1424 one of Al-Li-Mg system. Phase transformations were studied by means of fluorescence electron microscopy, micro-X-ray spectral analysis, X-ray phase analysis of single crystals and polycrystals and differential scanning calorimetry. For every alloy comparison of TTC and DPT enables to clarity the mechanism of phase composition effect on features and to optimize conditions of hardening cooling and ageing [ru

The dependence of Raman scattering on Mg concentration in Mg-doped GaN grown by MBE

International Nuclear Information System (INIS)

Flynn, Chris; Lee, William

2014-01-01

Magnesium-doped GaN (GaN:Mg) films having Mg concentrations in the range 5 × 10 18 –5 × 10 20 cm −3 were fabricated by molecular beam epitaxy. Raman spectroscopy was employed to study the effects of Mg incorporation on the positions of the E 2 and A 1 (LO) lines identifiable in the Raman spectra. For Mg concentrations in excess of 2 × 10 19 cm −3 , increases in the Mg concentration shift both lines to higher wave numbers. The shifts of the Raman lines reveal a trend towards compressive stress induced by incorporation of Mg into the GaN films. The observed correlation between the Mg concentration and the Raman line positions establish Raman spectroscopy as a useful tool for optimizing growth of Mg-doped GaN. (papers)

Applications of thermodynamic calculations to Mg alloy design: Mg-Sn based alloy development

International Nuclear Information System (INIS)

Jung, In-Ho; Park, Woo-Jin; Ahn, Sang Ho; Kang, Dae Hoon; Kim, Nack J.

2007-01-01

Recently an Mg-Sn based alloy system has been investigated actively in order to develop new magnesium alloys which have a stable structure and good mechanical properties at high temperatures. Thermodynamic modeling of the Mg-Al-Mn-Sb-Si-Sn-Zn system was performed based on available thermodynamic, phase equilibria and phase diagram data. Using the optimized database, the phase relationships of the Mg-Sn-Al-Zn alloys with additions of Si and Sb were calculated and compared with their experimental microstructures. It is shown that the calculated results are in good agreement with experimental microstructures, which proves the applicability of thermodynamic calculations for new Mg alloy design. All calculations were performed using FactSage thermochemical software. (orig.)

In vitro degradation and electrochemical corrosion evaluations of microarc oxidized pure Mg, Mg-Ca and Mg-Ca-Zn alloys for biomedical applications.

Science.gov (United States)

Pan, Yaokun; He, Siyu; Wang, Diangang; Huang, Danlan; Zheng, Tingting; Wang, Siqi; Dong, Pan; Chen, Chuanzhong

2015-02-01

Calcium phosphate (CaP) ceramic coatings were fabricated on pure magnesium (Mg) and self-designed Mg-0.6Ca, Mg-0.55Ca-1.74Zn alloys by microarc oxidation (MAO). The coating formation, growth and biomineralization mechanisms were discussed. The coating degradability and bioactivity were evaluated by immersion tests in trishydroxymethyl-aminomethane hydrochloric acid (Tris-HCl) buffer and simulated body fluid (SBF) solutions, respectively. The coatings and corrosion products were characterized by scanning electron microscope (SEM), X-ray diffractometer (XRD), X-ray photoelectron spectrometer (XPS) and fourier transform infrared spectrometer (FT-IR). The electrochemical workstation was used to investigate the electrochemical corrosion behaviors of substrates and coatings. Results showed that Mg-0.55Ca-1.74Zn alloy exhibits the highest mechanical strength and electrochemical corrosion resistance among the three alloys. The MAO-coated Mg-0.55Ca-1.74Zn alloy has the potential to be served as a biodegradable implant. Copyright © 2014 Elsevier B.V. All rights reserved.

Synthesis, crystal growth and structure of Mg containing β-rhombohedral boron: MgB17.4

International Nuclear Information System (INIS)

Adasch, Volker; Hess, Kai-Uwe; Ludwig, Thilo; Vojteer, Natascha; Hillebrecht, Harald

2006-01-01

For the first time, single crystals of Mg containing β-rhombohedral boron MgB 17.4 were synthesised from the elements in a Mg/Cu melt at 1600deg. C. The crystal structure determined by the refinement of single crystal data (space group R-3m, a=10.991(2)A, c=24.161(4)A, 890 reflections, 123 variables, R 1 (F)=0.049, wR 2 (I)=0.122) improves and modifies the former structure model derived from earlier investigations on powder samples. Mg is located on four different positions with partial occupation. While the occupation of the sites D (53.3%), E (91%) and F (7.2%) is already known from other boron-rich borides related to β-rhombohedral boron, the occupation of the fourth position (18h, 6.7%) is observed for the first time. Two boron positions show partial occupation. The summation reveals the composition MgB 17.4 and Mg 5.85 B 101.9 , respectively, confirmed by WDX measurements. The single crystals of MgB 17.4 show the highest Mg content ever found. Preliminary measurements indicate no superconductivity

Structural and electronic properties of Mg and Mg-Nb co-doped TiO2 (101) anatase surface

Energy Technology Data Exchange (ETDEWEB)

Sasani, Alireza [Department of Science, Karaj Islamic Azad University, Karaj, Alborz, P.O. Box 31485-313 (Iran, Islamic Republic of); Baktash, Ardeshir [Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of); Mirabbaszadeh, Kavoos, E-mail: mirabbas@aut.ac.ir [Department of Energy Engineering and Physics, Amirkabir University of Technology, Tehran, P. O. Box 15875-4413 (Iran, Islamic Republic of); Khoshnevisan, Bahram [Institute of Nano Science and Nano Technology, University of Kashan, Kashan, P.O. Box 87317-51167 (Iran, Islamic Republic of)

2016-10-30

Highlights: • Formation energy of Mg and Mg-Nb co-doped TiO{sub 2} anatase surface (101) is studied. • Effect of Mg defect to the TiO{sub 2} anatase (101) surface and bond length distribution of the surface is studied and it is shown that Mg defects tend to stay far from each other. • Effect of Mg and Nb to the bond length distribution of the surface studied and it is shown that these defects tend to stay close to each other. • Effects of Mg and Mg-Nb defects on DSSCs using TiO{sub 2} anatase hosting these defects are studied. - Abstract: In this paper, by using density functional theory, Mg and Nb-Mg co-doping of TiO{sub 2} anatase (101) surfaces are studied. By studying the formation energy of the defects and the bond length distribution of the surface, it is shown that Mg defects tend to stay as far as possible to induce least possible lattice distortion while Nb and Mg defects stay close to each other to cause less stress to the surface. By investigating band structure of the surface and changes stemmed from the defects, potential effects of Mg and Mg-Nb co-doping of TiO{sub 2} surface on dye-sensitized solar cells are investigated. In this study, it is shown that the Nb-Mg co-doping could increase J{sub SC} of the surface while slightly decreasing V{sub OC} compared to Mg doped surface, which might result in an increase in efficiency of the DSSCs compared to Nb or Mg doped surfaces.

Treatment with salvianolic acid B restores endothelial function in angiotensin II-induced hypertensive mice.

Science.gov (United States)

Ling, Wei Chih; Liu, Jian; Lau, Chi Wai; Murugan, Dharmani Devi; Mustafa, Mohd Rais; Huang, Yu

2017-07-15

Salvianolic acid B (Sal B) is one of the most abundant phenolic acids derived from the root of Danshen with potent anti-oxidative properties. The present study examined the vasoprotective effect of Sal B in hypertensive mice induced by angiotensin II (Ang II). Sal B (25mg/kg/day) was administered via oral gavage for 11days to Ang II (1.2mg/kg/day)-infused C57BL/6J mice (8-10weeks old). The vascular reactivity (both endothelium-dependent relaxations and contractions) in mouse arteries was examined by wire myography. The production of reactive oxygen species (ROS), protein level and localization of angiotensin AT 1 receptors and the proteins involved in ROS formation were evaluated using dihydroethidium (DHE) fluorescence, lucigenin-enhanced chemiluminescence, immunohistochemistry and Western blotting, respectively. The changes of ROS generating proteins were also assessed in vitro in human umbilical vein endothelial cells (HUVECs) exposed to Ang II with and without co-treatment with Sal B (0.1-10nM). Oral administration of Sal B reversed the Ang II-induced elevation of arterial systolic blood pressure in mice, augmented the impaired endothelium-dependent relaxations and attenuated the exaggerated endothelium-dependent contractions in both aortas and renal arteries of Ang II-infused mice. In addition, Sal B treatment normalized the elevated levels of AT 1 receptors, NADPH oxidase subunits (NOx-2 and NOx-4) and nitrotyrosine in arteries of Ang II-infused mice or in Ang II-treated HUVECs. In summary, the present study provided additional evidence demonstrating that Sal B treatment for 11days reverses the impaired endothelial function and with a marked inhibition of AT 1 receptor-dependent vascular oxidative stress. This vasoprotective and anti-oxidative action of Sal B most likely contributes to the anti-hypertensive action of the plant-derived compound. Copyright © 2017 Elsevier Inc. All rights reserved.

Cd(II) removal from aqueous solution by adsorption on α-ketoglutaric acid-modified magnetic chitosan

International Nuclear Information System (INIS)

Yang, Guide; Tang, Lin; Lei, Xiaoxia; Zeng, Guangming; Cai, Ye; Wei, Xue; Zhou, Yaoyu; Li, Sisi; Fang, Yan; Zhang, Yi

2014-01-01

The present study developed an α-ketoglutaric acid-modified magnetic chitosan (α-KA-Fe 3 O 4 /CS) for highly efficient adsorption of Cd(II) from aqueous solution. Several techniques, including transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and vibrating sample magnetometer (VSM), were applied to characterize the adsorbent. Batch tests were conducted to investigate the Cd(II) adsorption performance of α-KA-Fe 3 O 4 /CS. The maximum adsorption efficiency of Cd(II) appeared at pH 6.0 with the value of 93%. The adsorption amount was large and even reached 201.2 mg/g with the initial Cd(II) concentration of 1000 mg/L. The adsorption equilibrium was reached within 30 min and commendably described by pseudo-second-order model, and Langmuir model fitted the adsorption isotherm better. Furthermore, thermodynamic parameters, free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) of Cd(II) adsorption were also calculated and showed that the overall adsorption process was endothermic and spontaneous in nature because of positive ΔH values and negative ΔG values, respectively. Moreover, the Cd(II)-loaded α-KA-Fe 3 O 4 /CS could be regenerated by 0.02 mol/L NaOH solution, and the cadmium removal capacity could still be kept around 89% in the sixth cycle. All the results indicated that α-KA-Fe 3 O 4 /CS was a promising adsorbent in environment pollution cleanup.

Sorption behavior of Sn(II) onto Haro river sand from aqueous acidic solutions

International Nuclear Information System (INIS)

Hasany, S.M.; Khurshid, S.J.

1999-01-01

The sorption behavior of Sn(II) onto Haro river sand has been examined with respect to nature of electrolyte, agitation time, dosage of sorbent and concentration of sorbate. Maximum sorption (95.5%) has been achieved from 0.034M hydrochloric acid solution after equilibrating sorbate (2 x 10 -5 M) and sorbent (50 mg) for 120 minutes at a V/W ratio of 90 cm 3 x g -1 . The kinetic data have been subjected to Morris-Weber and Lagergren equations. The kinetics of sorption proceeds a two stage process consisting of a relatively slow initial uptake followed by a much rapid increase in the sorption. The rate constant of intraparticle transport, K d , comes out to be 8.75 x 10 -8 mol x g -1 x min -1/2 and the first order rate constant for sorption is 0.0416 min -1 . The sorption data of Sn(II) onto Haro river sand followed Langmuir, Freundlich and Dubinin-Radushkevich (D-R) type isotherms. The Langmuir constant, Q, related to sorption capacity and, b, related to sorption energy are computed to be 10.6±1.1 μmol x g -1 and 1123±137 dm 3 x mol -1 , respectively. The D-R isotherm yields the values of C m = 348±151 μmol x g -1 and β = -0.01044±0.0008 mol 2 x kJ -2 and of E = 6.9±0.3 kJ x mol -1 . In all three isotherms correlation factor (γ) is ≥ 0.99. The influence of common anions and cations on the sorption has been investigated. Zn(II), Mg(II), oxalate, Pb(II), Mn(II) and tartrate reduce the sorption significantly whereas Fe(II) causes substantial increase in the sorption. (author)

Phase I/II study of gefitinib (Iressa(®)) and vorinostat (IVORI) in previously treated patients with advanced non-small cell lung cancer.

Science.gov (United States)

Han, Ji-Youn; Lee, Soo Hyun; Lee, Geon Kook; Yun, Tak; Lee, Young Joo; Hwang, Kum Hui; Kim, Jin Young; Kim, Heung Tae

2015-03-01

Vorinostat has been shown to overcome resistance to gefitinib. We performed a phase I/II study combining gefitinib with vorinostat in previously treated non-small cell lung cancer (NSCLC). A 3 + 3 dose-escalation design was used to determine maximum tolerated dose (MTD) and recommended phase II dose (RP2D). Three dose levels were tested: 250 mg/day gefitinib on days 1-28 and 200, 300 or 400 mg/day vorinostat on days 1-7, and 15-21 out of every 28 days. The primary endpoint was median progression-free survival (PFS). Fifty-two patients were enrolled and treated (43 in phase II). The median age was 59 years, 28 patients were male, 44 had adenocarcinoma, 29 had never smoked, and 36 had undergone one prior treatment. Twenty-two patients exhibited sensitive EGFR mutations. Planned dose escalation was completed without reaching the MTD. The RP2D was 250 mg gefitinib and 400 mg vorinostat. In 43 assessable patients in phase II, the median PFS was 3.2 months; the overall survival (OS) was 19.0 months. There were 16 partial responses and six cases of stable disease. In EGFR-mutant NSCLC, response rate was 77 %, median PFS was 9.1 months, and median OS was 24.1 months. The most common adverse events were anorexia and diarrhea. Treatment with 250 mg gefitinib daily with biweekly 400 mg/day vorinostat was feasible and well tolerated. In an unselected patient population, this combination dose did not improve PFS. However, this combination showed a potential for improving efficacy of gefitinib in EGFR-mutant NSCLC (NCT01027676).

Removal of cadmium(II) from aqueous solutions by steam-activated ...

African Journals Online (AJOL)

Removal of cadmium(II) from aqueous solutions by steam-activated sulphurised carbon prepared from sugar-cane bagasse pith: kinetics and equilibrium studies. ... the maximum adsorption capacity of SA-S-C calculated by the Langmuir isotherm is 149.93 mg/g at 30°C. Acid regeneration was tried for several cycles with a ...

Mn(II), Zn(II) and VO(II) Schiff

Indian Academy of Sciences (India)

Home; Journals; Journal of Chemical Sciences; Volume 113; Issue 3. Synthesis and characterisation of Cu(II), Ni(II), Mn(II), Zn(II) and VO(II) Schiff base complexes derived from o-phenylenediamine and acetoacetanilide. N Raman Y Pitchaikani Raja A Kulandaisamy. Inorganic Volume 113 Issue 3 June 2001 pp 183-189 ...

Phase II study of Gleevec® plus hydroxyurea (HU) in adults with progressive or recurrent meningioma.

Science.gov (United States)

Reardon, David A; Norden, Andrew D; Desjardins, Annick; Vredenburgh, James J; Herndon, James E; Coan, April; Sampson, John H; Gururangan, Sridharan; Peters, Katherine B; McLendon, Roger E; Norfleet, Julie A; Lipp, Eric S; Drappatz, Jan; Wen, Patrick Y; Friedman, Henry S

2012-01-01

We prospectively evaluated the efficacy and safety of imatinib plus hydroxyurea in patients with progressive/recurrent meningioma. A total of 21 patients with progressive/recurrent meningioma were enrolled in this dual center, single-arm, phase II trial. All patients received 500 mg of hydroxyurea twice a day. Imatinib was administered at 400 mg/day for patients not on CYP3A enzyme inducing anti-epileptic drugs (EIAEDs) and at 500 mg twice a day for patients on EIAEDs. The primary endpoint was progression-free survival at 6 months (PFS-6) and secondary endpoints were safety, radiographic response rate, and overall survival (OS). Best radiographic response was stable disease and was observed in 14 patients (67%). PFS-6 for all patients, those with grade I tumors (n = 8) and those with grade II or III tumors (n = 13) was 61.9, 87.5 and 46.2%, respectively. Patients with grade II or III tumors had poorer PFS and OS than those with grade I tumors, (P = 0.025 and P = 0.018) respectively. The only grade 3 or greater adverse event occurring in ≥ 10% of patients was anemia (10%). Imatinib plus hydroxyurea is well tolerated among patients with meningioma but has modest anti-tumor activity for this indication.

Effect of sterilization process on surface characteristics and biocompatibility of pure Mg and MgCa alloys

International Nuclear Information System (INIS)

Liu, X.L.; Zhou, W.R.; Wu, Y.H.; Cheng, Y.; Zheng, Y.F.

2013-01-01

The aim of this work was to investigate the effect of various sterilization methods on surface characteristics and biocompatibility of MgCa alloy, with pure Mg as a comparison, including steam autoclave sterilization (SA), ethylene oxide steam sterilization (EO), glutaraldehyde sterilization (GD), dry heat sterilization (DH) and Co60 γ ray radiation sterilization (R) technologies. The surface characterizations were performed by environmental scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, grazing incidence X-ray diffraction, water contact angle and surface free energy measurement, whereas the cytotoxicity and hemocompatibility were evaluated by cellular adhesive experiment, platelet adhesion and hemolysis test. The results showed that the five sterilization processes caused more changes on the surface of MgCa alloy than that on the surface of pure Mg. The GD sterilization caused the most obvious changes on the surface of the pure Mg, and the SA sterilization made the largest alteration on the MgCa alloy surface. The GD and DH sterilization processes could cause increases on surface free energy for both pure Mg and MgCa alloys, while the other three sterilization processes reduced the surface free energy. The DH and GD sterilization processes caused the least alteration on the cell adhesion on pure Mg surface, whereas the EO sterilization performed the greatest impact on the cell adhesion on the Mg–Ca alloy surface. The hemolysis percentage of pure Mg and MgCa alloys were reduced by SA sterilization, meanwhile the other four sterilization processes increased their hemolysis percentages significantly, especially for the EO sterilization. - Highlights: • The effect of sterilization on surface chemistry and biocompatibility was studied. • Sterilization caused more surface changes on MgCa alloy than pure Mg. • Co60 γ ray radiation is the most appropriate sterilization process

Stabilization of the dissipation-free current transport in inhomogeneous MgB2 thin films

International Nuclear Information System (INIS)

Treiber, S.; Stahl, C.; Schütz, G.; Soltan, S.; Albrecht, J.

2014-01-01

Highlights: • We investigate transport properties of inhomogeneous MgB 2 films. • An inhomogeneous microstructure stabilizes supercurrents. • Vortex pinning forces and energies have been analyzed experimentally. • In inhomogeneous films the increase of the pinning energy is responsible for stable supercurrents. - Abstract: In type-II superconductors at T = 0 the critical current density is determined by the pinning of flux lines. Considering an arbitrarily shaped energy landscape the pinning force at each pinning site is given by the derivative of the flux line energy with respect to the considered direction. At finite temperatures, in addition, thermal activation can lead to a depinning of flux lines. The governing property in this case is the depth of the corresponding pinning potential, i.e. the pinning energy. We show a detailed analysis of both pinning forces and pinning energies of MgB 2 films with inhomogeneous microstructure. We show that a pronounced increase of the pinning energy is responsible for the significantly enhanced stability of the dissipation-free current transport in thin inhomogeneous MgB 2 films. This is found even if the corresponding pinning forces are small

A study on preparation and hydriding of β-Mg2Al3 and γ-Mg17Al12

International Nuclear Information System (INIS)

Hadi Suwarno

2009-01-01

The mechanism of the synthetic formation of β-Mg 2 Al 3 and γ-Mg 17 Al 12 has been studied. Mechanical alloying of Mg and Al powders with the atomic ratio of Mg:Al = 2:3 in toluene solution yields β-Mg 2 Al 3 compound after milling for 30 h. The γ-Mg 17 Al 12 can be formed by heating the β-Mg 2 Al 3 at 430°C under high vacuum. The measured hydrogen capacities of β-Mg 2 Al 3 and γ-Mg 17 Al 12 as hydride at 300°C are 3.2 and 4.9 wt%, respectively. Microstructure of the Mg-Al specimen shows that on hydriding at 300°C the polygonal shape of the γ-Mg 17 Al 12 changes into irregular shapes which are composed of γ-MgH 2 and Al. (author)

Mg concentration profile and its control in the low temperature grown Mg-doped GaN epilayer

Science.gov (United States)

Liu, S. T.; Yang, J.; Zhao, D. G.; Jiang, D. S.; Liang, F.; Chen, P.; Zhu, J. J.; Liu, Z. S.; Liu, W.; Xing, Y.; Zhang, L. Q.; Wang, W. J.; Li, M.; Zhang, Y. T.; Du, G. T.

2018-01-01

In this work, the Cp2Mg flux and growth pressure influence to Mg doping concentration and depth profiles is studied. From the SIMS measurement we found that a transition layer exists at the bottom region of the layer in which the Mg doping concentration changes gradually. The thickness of transition layer decreases with the increases of Mg doping concentration. Through analysis, we found that this is caused by Ga memory effect which the Ga atoms stay residual in MOCVD system will react with Mg source, leading a transition layer formation and improve the growth rate. And the Ga memory effect can be well suppressed by increasing Mg doping concentration and growth pressure and thus get a steep Mg doping at the bottom region of p type layer.

Solid-liquid stable phase equilibria of the ternary systems MgCl2 + MgB6O10+ H2O AND MgSO4 + MgB6O10 + H2O at 308.15 K

Directory of Open Access Journals (Sweden)

Lingzong Meng

2014-03-01

Full Text Available The solubilities and the relevant physicochemical properties of the ternary systems MgCl2 + MgB6O10 + H2O and MgSO4 + MgB6O10 + H2O at 308.15 K were investigated using an isothermal dissolution method. It was found that there is one invariant point, two univariant curves, and two crystallization regions of the systems. The systems belong to a simple co-saturated type, and neither double salts nor solid solutions were found. Based on the extended HW model and its temperature-dependent equations, the single-salt Pitzer parameters β(0, β(1, β(2 and CØ for MgCl2, MgSO4, and Mg(B6O7(OH6, the mixed ion-interaction parameters θCl,B6O10, θSO4,B6O10, ΨMg,Cl,B6O10, ΨMg,SO4,B6O10 of the systems at 308.15 K were fitted, In addition, the average equilibrium constants of the stable equilibrium solids at 308.15 K were obtained by a method using the activity product constant. Then the solubilities of the ternary systems are calculated. The calculated solubilities agree well with the experimental values.

A Phase I/II Clinical Trial of Belinostat (PXD101) in Combination with Doxorubicin in Patients with Soft Tissue Sarcomas

DEFF Research Database (Denmark)

Vitfell-Rasmussen, Joanna; Judson, Ian; Safwat, Akmal Ahmed

2016-01-01

) and 75 mg/m(2) Dox. Results. 41 patients were included (25 in phase I, 16 in phase II). Adverse events were fatigue (95%), nausea (76%), and alopecia (63%). There was one DLT, grade 3 rash/hand and foot syndrome. MTD was Bel 1000 mg/m(2)/d and Dox 75 mg/m(2). Four responses were seen: 2 PR in phase I, RR...

Filtration experiments of the KNK II primary sodium

International Nuclear Information System (INIS)

Stamm, H.H.

1987-01-01

The separated particles of the KNK primary sodium are a result of a normal corrosion rate by using ferritic and austenitic steels in sodium. Similar particle distributions and concentrations were found in primary circuits of other breeder plants (EBR-II et al). The experimental results of the particle concentration in the KNK primary sodium were lower than the theoretical calculation. Based on a corrosion rate of 0.5 micron/y for austenitic steels and a corrosion rate of 1.5 mg/square-cm y for a ferritic steel used in KNK as structure material an equilibrium particle concentration of 1.066 mg/kg Na was calculated. The experimental results of particle size are not in agreement with theoretical calculation of the BACCHUS code. (orig.)

Structural and optical properties of ZnMgO nanostructures formed by Mg in-diffused ZnO nanowires

International Nuclear Information System (INIS)

Pan, C.-J.; Hsu, H.-C.; Cheng, H.-M.; Wu, C.-Y.; Hsieh, W.-F.

2007-01-01

ZnMgO nanostructures with wurtzite phase were prepared by thermal diffusion of Mg into the ZnO nanowires. As ZnO light-emitting devices have been operated by using ZnMgO layers as energy barrier layers to confine the carriers, it is essential to realize the characterization of ZnMgO particularly. In this work, the Mg content in Zn 1 -x Mg x O alloy determined by X-ray diffraction (XRD) and photoluminescence (PL) shows a good coincidence. The variation of lattice constant and the blueshift of near-band-edge emission indicate that Zn 2+ ions are successfully substituted by Mg 2+ ions in the ZnO lattice. In Raman-scattering studies, the change of E 2 (high) phonon line shape in ZnO:Mg nanostructures reveals the microscopic substitutional disorder. In addition to the host phonons of ZnO, two additional bands around 383 and 510 cm -1 are presumably attributed to the Mg-related vibrational modes. - Graphical abstract: We reported the synthesis of the ZnMgO nanostructures prepared by a simple vapor transport method. Magnesium-related anomalous modes are observed by Raman spectra for the first time in ZnMgO system

Hydrogen absorption kinetics and structural properties of Mg85Ni10Ca5 and Mg90Ni10

International Nuclear Information System (INIS)

Aoki, Masakazu; Saito, Katsushi; Towata, Shin-ichi

2005-01-01

Mg 85 Ni 10 Ca 5 and Mg 90 Ni 10 were prepared by melting mixtures of the elements in mild steel crucibles and pouring them into copper molds. Hydrogen absorption kinetics and structural properties of the alloys were characterized by the volumetric method using a Sievert's apparatus, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The crystallite size of Mg in Mg 85 Ni 10 Ca 5 , which is evaluated by XRD peak broadening, is about 50% smaller than that in Mg 90 Ni 10 . In addition, the nanometer-scale structure composed of Mg, Mg 2 Ni, Mg 2 Ca was observed in Mg 85 Ni 10 Ca 5 . Mg 85 Ni 10 Ca 5 shows better hydrogen absorption kinetics than Mg 90 Ni 10 in the temperature range of room temperature to 573 K. The better absorption kinetics of Mg 85 Ni 10 Ca 5 is mainly attributed to the nanometer-scale structure

EPOXYEICOSATRIENOIC ACID ANALOG ATTENUATES ANGIOTENSIN II HYPERTENSION AND KIDNEY INJURY

Directory of Open Access Journals (Sweden)

Md. Abdul Hye Khan

2014-09-01

Full Text Available Epoxyeicosatrienoic acids (EETs contribute to blood pressure regulation leading to the concept that EETs can be therapeutically targeted for hypertension and the associated end-organ damage. In the present study, we investigated anti-hypertensive and kidney protective actions of an EET analog, EET-B in angiotensin II (ANG II-induced hypertension. EET-B was administered in drinking water for 14 days (10mg/kg/d and resulted in a decreased blood pressure elevation in ANG II hypertension. At the end of the two-week period, blood pressure was 30 mmHg lower in EET analog-treated ANG II hypertensive rats. The vasodilation of mesenteric resistance arteries to acetylcholine was impaired in ANG II hypertension; however, it was improved with EET-B treatment. Further, EET-B protected the kidney in ANG II hypertension as evidenced by a marked 90% decrease in albuminuria and 54% decrease in nephrinuria. Kidney histology demonstrated a decrease in renal tubular cast formation in EET analog-treated hypertensive rats. In ANG II hypertension, EET-B treatment markedly lowered renal inflammation. Urinary monocyte chemoattractant protein-1 excretion was decreased by 55% and kidney macrophage infiltration was reduced by 52% with EET-B treatment. Overall, our results demonstrate that EET-B has anti-hypertensive properties, improves vascular function, and decreases renal inflammation and injury in ANG II hypertension.

Enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers by inhibiting Ta diffusion

Energy Technology Data Exchange (ETDEWEB)

Li, Xu-Jing; Jiang, Shao-Long; Zhang, Jing-Yan; Liu, Qian-Qian; Liu, Yi-Wei; Zhao, Jian-Cheng [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Wu, Zheng-Long [Analytical and Testing Center, Beijing Normal University, Beijing 100875 (China); Feng, Chun, E-mail: fengchun@ustb.edu.cn [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Li, Ming-Hua [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China); Yu, Guang-Hua, E-mail: ghyu@mater.ustb.edu.cn [Department of Materials Physics and Chemistry, University of Science and Technology Beijing, Beijing 100083 (China)

2016-03-01

Graphical abstract: To reveal the underlying mechanism of Mg influence on the enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers, the X-ray photoelectron spectroscopy analysis have been performed. It is found that a certain amount of Mg interlayer at the CoFeB/MgO interface could prevent the Ta oxidation to some extent due to the oxygen deficit MgO{sub x} (x < 1), and consequently lower the diffusion motivation of Ta from the bottom layer to the CoFeB/MgO interfaces to some extent during the annealing process. The prevention of Ta diffusion realizes the effective hybridization of Fe and O at the CoFeB/MgO interface and maintains interfacial magnetic anisotropy (K{sub CoFeB/MgO}). As a result, the perpendicular magnetic anisotropy at high annealing temperatures was maintained. - Highlights: • High annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers was realized. • X-ray photoelectron spectroscopy analysis has been performed to explore the reasons. • The prevention of Ta diffusion was realized by introducing Mg at the CoFeB/MgO interface. - Abstracts: To reveal the underlying mechanism of Mg influence on the enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers, the X-ray photoelectron spectroscopy analysis has been performed. It is found that a certain amount of Mg interlayer at the CoFeB/MgO interface could prevent the Ta oxidation, and consequently lower the diffusion motivation of Ta from the bottom layer to the CoFeB/MgO interfaces to some extent in the annealing process. The prevention of Ta diffusion realizes the effective hybridization of Fe and O at the CoFeB/MgO interface and maintains interfacial magnetic anisotropy (KCoFeB/MgO). As a result, the perpendicular magnetic anisotropy at high annealing temperatures is maintained.

Synthesis and characterization of 2,3,13,14-tetramethyl (ethyl or p-tolyl-1,4,12,15-tetraazacyclodocosa-1,3,12,14-tetraene complexes of Mg(II, Ca(II, Sr(II and Ba(II

Directory of Open Access Journals (Sweden)

SEEMA GUPTA

2002-07-01

Full Text Available 2+2 Cyclocondensation of 1,7-diaminoheptane with a-diketones, viz. 2,3-butanedione, 3,4-hexanedione or 4,4’-dimethylbenzil, in the presence of Mg2+, Ca2+, Sr2+ and Ba2+ ions as templates yields a series of complexes of the type [ML(X2] (where L = N4 macrocycle having a 22-membered ring and X = Cl or NCS. The resulting complexes were characterized by elemental analysis, conductance measurements and IR and 1H-NMR spectral studies.

Adsorption of Pb(II), Cu(II), Cd(II), Zn(II), Ni(II), Fe(II), and As(V) on bacterially produced metal sulfides.

Science.gov (United States)

Jong, Tony; Parry, David L

2004-07-01

The adsorption of Pb(II), Cu(II), Cd(II), Zn(II), Ni(II), Fe(II) and As(V) onto bacterially produced metal sulfide (BPMS) material was investigated using a batch equilibrium method. It was found that the sulfide material had adsorptive properties comparable with those of other adsorbents with respect to the specific uptake of a range of metals and, the levels to which dissolved metal concentrations in solution can be reduced. The percentage of adsorption increased with increasing pH and adsorbent dose, but decreased with increasing initial dissolved metal concentration. The pH of the solution was the most important parameter controlling adsorption of Cd(II), Cu(II), Fe(II), Ni(II), Pb(II), Zn(II), and As(V) by BPMS. The adsorption data were successfully modeled using the Langmuir adsorption isotherm. Desorption experiments showed that the reversibility of adsorption was low, suggesting high-affinity adsorption governed by chemisorption. The mechanism of adsorption for the divalent metals was thought to be the formation of strong, inner-sphere complexes involving surface hydroxyl groups. However, the mechanism for the adsorption of As(V) by BPMS appears to be distinct from that of surface hydroxyl exchange. These results have important implications to the management of metal sulfide sludge produced by bacterial sulfate reduction.

Porphyrin-functionalized porous polysulfone membrane towards an optical sensor membrane for sorption and detection of cadmium(II)

Energy Technology Data Exchange (ETDEWEB)

Zhao, Lizhi, E-mail: zhaolizhi_phd@163.com [State Key Laboratory of Separation Membranes and Membrane Processes, School of Materials Science and Engineering, Tianjin Polytechnic University, Tianjin 300387 (China); Li, Min; Liu, Manman; Zhang, Yuecong [State Key Laboratory of Separation Membranes and Membrane Processes, School of Materials Science and Engineering, Tianjin Polytechnic University, Tianjin 300387 (China); Wu, Chenglin [School of Pharmaceutical and Chemical Engineering, Taizhou University, Taizhou 317000, Zhejiang Province (China); Zhang, Yuzhong, E-mail: zhangyz2004cn@163.com [State Key Laboratory of Separation Membranes and Membrane Processes, School of Materials Science and Engineering, Tianjin Polytechnic University, Tianjin 300387 (China)

2016-01-15

Highlights: • An optical sensor membrane is prepared by TMPyP and PNaSS-grafted PSF membrane. • The optical sensor membrane shows enhanced sorption for cadmium(II). • Visual and spectrophotometric detection can be achieved. • The functional membrane exhibits good stability and reusability. - Abstract: In this study, an optical sensor membrane was prepared for sorption and detection of cadmium(II) (Cd(II)) in aqueous solution. A polyanion, poly(sodium 4-styrenesulfonate) (PNaSS), was grafted onto the chloromethylated polysulfone (CMPSF) microporous membrane via surface-initiated ATRP. 5,10,15,20-tetrakis(4-N-methylpyridyl) porphyrin p-toluenesulfonate (TMPyP) was immobilized onto the PNaSS-grafted polysulfone (PSF-PNaSS) membrane through electrostatic interaction. The TMPyP-functionalized membrane exhibited an enhanced sorption for, and distinct color and spectral response to cadmium(II) (Cd(II)) in aqueous solution. Larger immobilization capacity of TMPyP on the membrane led to stronger sorption for Cd(II), and smaller one made the optical sensor have a faster (in minutes) and more sensitive response to the ion. The detection limit study indicated that the functional membrane with proper amount of TMPyP (<0.5 mg/g) could still have color and spectral response to Cd(II) solutions at an extreme low concentration (10{sup −4} mg/L). The optical sensor membrane exhibited good stability and reusability which made it efficient for various sorptive removal and detection applications.

Evaluation of Fe(II) oxidation at an acid mine drainage site using laboratory-scale reactors

Science.gov (United States)

Brown, Juliana; Burgos, William

2010-05-01

Acid mine drainage (AMD) is a severe environmental threat to the Appalachian region of the Eastern United States. The Susquehanna and Potomac River basins of Pennsylvania drain to the Chesapeake Bay, which is heavily polluted by acidity and metals from AMD. This study attempted to unravel the complex relationships between AMD geochemistry, microbial communities, hydrodynamic conditions, and the mineral precipitates for low-pH Fe mounds formed downstream of deep mine discharges, such as Lower Red Eyes in Somerset County, PA, USA. This site is contaminated with high concentrations of Fe (550 mg/L), Mn (115 mg/L), and other trace metals. At the site 95% of dissolved Fe(II) and 56% of total dissolved Fe is removed without treatment, across the mound, but there is no change in the concentration of trace metals. Fe(III) oxides were collected across the Red Eyes Fe mound and precipitates were analyzed by X-ray diffraction, electron microscopy and elemental analysis. Schwertmannite was the dominant mineral phase with traces of goethite. The precipitates also contained minor amounts of Al2O3, MgO,and P2O5. Laboratory flow-through reactors were constructed to quantify Fe(II) oxidation and Fe removal over time at terrace and pool depositional facies. Conditions such as residence time, number of reactors in sequence and water column height were varied to determine optimal conditions for Fe removal. Reactors with sediments collected from an upstream terrace oxidized more than 50% of dissolved Fe(II) at a ten hour residence time, while upstream pool sediments only oxidized 40% of dissolved Fe(II). Downstream terrace and pool sediments were only capable of oxidizing 25% and 20% of Fe(II), respectively. Fe(II) oxidation rates measured in the reactors were determined to be between 3.99 x 10-8and 1.94 x 10-7mol L-1s-1. The sediments were not as efficient for total dissolved Fe removal and only 25% was removed under optimal conditions. The removal efficiency for all sediments

Pharmacological characterization of BR-A-657, a highly potent nonpeptide angiotensin II receptor antagonist.

Science.gov (United States)

Chi, Yong Ha; Lee, Joo Han; Kim, Je Hak; Tan, Hyun Kwang; Kim, Sang Lin; Lee, Jae Yeol; Rim, Hong-Kun; Paik, Soo Heui; Lee, Kyung-Tae

2013-01-01

The pharmacological profile of BR-A-657, 2-n-butyl-5-dimethylamino-thiocarbonyl-methyl-6-methyl-3-{[2-(1H-tetrazole-5-yl)biphenyl-4-yl]methyl}-pyrimidin-4(3H)-one, a new nonpeptide AT1-selective angiotensin receptor antagonist, has been investigated in a variety of in vitro and in vivo experimental models. In the present study, BR-A-657 displaced [(125)I][Sar(1)-Ile(8)]angiotensin II (Ang II) from its specific binding sites to AT1 subtype receptors in membrane fractions of HEK-293 cells with an IC50 of 0.16 nM. In a functional assay using isolated rabbit thoracic aorta, BR-A-657 inhibited the contractile response to Ang II (pD'2: 9.15) with a significant reduction in the maximum. In conscious rats, BR-A-657 (0.01, 0.1, 1 mg/kg; intravenously (i.v.)) dose-dependently antagonized Ang II-induced pressor responses. In addition, BR-A-657 dose-dependently decreased mean arterial pressure in furosemide-treated rats and renal hypertensive rats. Moreover, BR-A-657 given orally at 1 and 3 mg/kg reduced blood pressure in conscious renal hypertensive rats. Taken together, these findings indicate that BR-A-657 is a potent and specific antagonist of Ang II at the AT1 receptor subtype, and reveal the molecular basis responsible for the marked lowering of blood pressure in conscious rats.

Respiratory outcomes following 100 mg/kg v. 200 mg/kg of poractant ...

African Journals Online (AJOL)

In keeping with current evidence, the initial dose of poractant alpha was increased from 100 mg/kg to 200 mg/kg. e outcomes of newborns requiring treatment with surfactant before and aer this change were reviewed. Methods. Electronic clinical records were reviewed of infants admitted to ACH who received surfactant ...

Mg/Ca ratio in fertilization and agricultural soils, Mg percent of liming ...

African Journals Online (AJOL)

Strong increase of NPK (nitrogen, phosphorus and potassium) in mineral fertilization (fm) included relative delay in Mg supplementation and dilution in plant available silicon (Si) via recycled nutrients (rcl). (Silicon is not included in essential fertilizers in Finland.) Methods: We have assessed old data on Ca and Mg in ...

Enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers by inhibiting Ta diffusion

International Nuclear Information System (INIS)

Li, Xu-Jing; Jiang, Shao-Long; Zhang, Jing-Yan; Liu, Qian-Qian; Liu, Yi-Wei; Zhao, Jian-Cheng; Wu, Zheng-Long; Feng, Chun; Li, Ming-Hua; Yu, Guang-Hua

2016-01-01

Graphical abstract: To reveal the underlying mechanism of Mg influence on the enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers, the X-ray photoelectron spectroscopy analysis have been performed. It is found that a certain amount of Mg interlayer at the CoFeB/MgO interface could prevent the Ta oxidation to some extent due to the oxygen deficit MgO_x (x < 1), and consequently lower the diffusion motivation of Ta from the bottom layer to the CoFeB/MgO interfaces to some extent during the annealing process. The prevention of Ta diffusion realizes the effective hybridization of Fe and O at the CoFeB/MgO interface and maintains interfacial magnetic anisotropy (K_C_o_F_e_B_/_M_g_O). As a result, the perpendicular magnetic anisotropy at high annealing temperatures was maintained. - Highlights: • High annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers was realized. • X-ray photoelectron spectroscopy analysis has been performed to explore the reasons. • The prevention of Ta diffusion was realized by introducing Mg at the CoFeB/MgO interface. - Abstracts: To reveal the underlying mechanism of Mg influence on the enhanced post-annealing stability of perpendicular Ta/CoFeB/Mg/MgO multilayers, the X-ray photoelectron spectroscopy analysis has been performed. It is found that a certain amount of Mg interlayer at the CoFeB/MgO interface could prevent the Ta oxidation, and consequently lower the diffusion motivation of Ta from the bottom layer to the CoFeB/MgO interfaces to some extent in the annealing process. The prevention of Ta diffusion realizes the effective hybridization of Fe and O at the CoFeB/MgO interface and maintains interfacial magnetic anisotropy (KCoFeB/MgO). As a result, the perpendicular magnetic anisotropy at high annealing temperatures is maintained

Effect of Blood Glucose Fluctuation on Some Trace Elements and Aldosterone Hormone among Type II Diabetic Patients with Metabolic Syndrome

International Nuclear Information System (INIS)

Ezz El-Arab, A.; El Fouly, A.H.; Mahmoud, H.H.

2014-01-01

There is accumulating evidence determine that the metabolism of some trace elements is altered in diabetes mellitus (DM) type II. The current study aimed to evaluate the effect of serum blood glucose fluctuation during (Random, Fasting and Postprandial 2 hours state) on some trace elements such as Cadmium (Cd), Chromium (Cr), Manganese (Mn), Magnesium (Mg), Zinc (Zn), Copper (Cu), Sodium (Na), Potassium (K), and Aldosterone hormone in type II Diabetic patients associated with metabolic syndrome in comparison with healthy volunteers. The International Diabetes Federation (IFD) consensus the diagnosis of metabolic syndrome according to central obesity, lipid profile, blood glucose level and blood pressure. A significant change was observed in trace elements level (Cd, Cr, Mg, Mn, Zn, Cu, Na, and K) and Aldosterone hormone as a result of glucose fluctuation among type II diabetic patients.

Efficacy and tolerability of an undenatured type II collagen supplement in modulating knee osteoarthritis symptoms: a multicenter randomized, double-blind, placebo-controlled study.

Science.gov (United States)

Lugo, James P; Saiyed, Zainulabedin M; Lane, Nancy E

2016-01-29

Undenatured type II collagen (UC-II) is a nutritional supplement derived from chicken sternum cartilage. The purpose of this study was to evaluate the efficacy and tolerability of UC-II for knee osteoarthritis (OA) pain and associated symptoms compared to placebo and to glucosamine hydrochloride plus chondroitin sulfate (GC). One hundred ninety one volunteers were randomized into three groups receiving a daily dose of UC-II (40 mg), GC (1500 mg G & 1200 mg C), or placebo for a 180-day period. The primary endpoint was the change in total Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) from baseline through day 180 for the UC-II group versus placebo and GC. Secondary endpoints included the Lequesne Functional Index (LFI), the Visual Analog Scale (VAS) for pain and the WOMAC subscales. Modified intent-to-treat analysis were performed for all endpoints using analysis of covariance and mixed model repeated measures, while incremental area under the curve was calculated by the intent-to-treat method. At day 180, the UC-II group demonstrated a significant reduction in overall WOMAC score compared to placebo (p = 0.002) and GC (p = 0.04). Supplementation with UC-II also resulted in significant changes for all three WOMAC subscales: pain (p = 0.0003 vs. placebo; p = 0.016 vs. GC); stiffness (p = 0.004 vs. placebo; p = 0.044 vs. GC); physical function (p = 0.007 vs. placebo). Safety outcomes did not differ among the groups. UC-II improved knee joint symptoms in knee OA subjects and was well-tolerated. Additional studies that elucidate the mechanism for this supplement's actions are warranted. CTRI/2013/05/003663 ; CTRI/2013/02/003348 .

Eight joint BER II and BESSY II users meeting. Abstracts

International Nuclear Information System (INIS)

2016-01-01

The following topics were dealt with: Accelerator operation and projecs, photon science and instrumentation at BESSY II, status of energy materials in-situ Lab at BESSY II, high resolution spectrometer PEAXIS at BESSY II, sample environment at BESSY II, molecular control mechanisms in the Brr2 RNA helicase for efficient and regulated splicing, the Li conversion reaction of 4CoFe_2O_4 nanoparticles, buried interfaces in lithium ion batteries probed with HAXPES, ARPES studies of the STO(001) 2DEG, all-in/all-out magnetic order in rare earth iridates, oxygen reduction reaction on graphene in Li-air batteries, electronic order in high-T_c superconductors, in-siu observation of novel switching phenomena in highly porous metal-organic frameworks, photoinduced demagnetization and insulator-to-metal transition in ferromagnetic insulating BaFeO_3 thin films, ARPES measurement of the ferroelectric bulk Rashba system GeTe, bisphenol A on Cu(111) and Ag(111), reverse water-gas shift or Sabathier methanation on N(110), structural studies of molecular machines, multi-MHz time-of-flight electronic band-structure imaging of graphene on Ir(111), diffusion pathways in ion conductors, ground-state potential energy surfaces around selected atoms from resonant inelastic X-ray scattering, solar energy in an emerging country, in-situ neutron analysis of electrode materials for electrochemical energy storage, structure and transport properties in thermoelectric skutterudites, investigation of the interphase formation on solid lithium-ion conductors by neutron reflectometry, load partitin and damage characterization of cast AlSi_1_2CuMgNi alloy with ceramic reinforcement, methane adsorption in highly porous metal-organics, structure and magnetic interactions in dimer system Ba_(_3_-_x_)Sr_xCr_2O_8, distribution of S in C-S nanocomposites, current status of HFM-EXED FACITIY; SPIN NEAMTICITY IN s=1/2 frustrated zigzag chaIN β-TeVO_4, electronic properties of U(Ru_0_._9_2Rh_0_._0_8)_2Si_2 in

Removal of Mn(II) from the acid mine wastewaters using coal fired bottom ash

Science.gov (United States)

Mahidin, M.; Sulaiman, T. N.; Muslim, A.; Gani, A.

2017-06-01

Acid mine wastewater (AMW), the wastewater from mining activities which has low pH about 3-5 and contains hazardous heavy metals such as Cu, Fe, Mn, Zn, Pb, etc. Those heavy metals pollution is of prime concern from the environmental view point. Among the heavy metals, Mn occupies the third position in the AMW from one the iron ore mining company in Aceh, Indonesia. In this study, the possibility use of bottom ash from coal fired boiler of steam power plants for the removal of Mn(II) in AMW has been investigated. Experimental has been conducted as follows. Activation of bottom ash was done both by physical and chemical treatments through heating at 270 °C and washing with NaOH activator 0.5 and 1 M. Adsorption test contains two parts observation; preliminary and primary experiments. Preliminary study is addressed to select the best condition of three independent variables i.e.: pH of AMW (3 & 7), bottom ash particle size (40, 60 & 100 mesh) and initial Mn(II) concentrations (100 & 600 mg/l). AMW used was synthetics wastewater. It was found that the best value for NaOH is 1 M, pH is 7, particle size is 100 meshes and initial Mn(II) concentration is 600 mg/l from the adsorption efficiency point of view. The maximum adsorption capacity (q e) is 63.7 mg/g with the efficiency of 85%.

Effect of amorphous Mg50Ni50 on hydriding and dehydriding behavior of Mg2Ni alloy

International Nuclear Information System (INIS)

Guzman, D.; Ordonez, S.; Fernandez, J.F.; Sanchez, C.; Serafini, D.; Rojas, P.A.; Aguilar, C.; Tapia, P.

2011-01-01

Composite Mg 2 Ni (25 wt.%) amorphous Mg 50 Ni 50 was prepared by mechanical milling starting with nanocrystalline Mg 2 Ni and amorphous Mg 50 Ni 50 powders, by using a SPEX 8000 D mill. The morphological and microstructural characterization of the powders was performed via scanning electron microscopy and X-ray diffraction. The hydriding characterization of the composite was performed via a solid gas reaction method in a Sievert's-type apparatus at 363 K under an initial hydrogen pressure of 2 MPa. The dehydriding behavior was studied by differential thermogravimetry. On the basis of the results, it is possible to conclude that amorphous Mg 50 Ni 50 improved the hydriding and dehydriding kinetics of Mg 2 Ni alloy upon cycling. A tentative rationalization of experimental observations is proposed. - Research Highlights: → First study of the hydriding behavior of composite Mg 2 Ni (25 wt.%) amorphous Mg 50 Ni 50 . → Microstructural characterization of composite material using XRD and SEM was obtained. → An improved effect of Mg 50 Ni 50 on the Mg 2 Ni hydriding behavior was verified. → The apparent activation energy for the hydrogen desorption of composite was obtained.

Synthesis of Mg(OH)₂, MgO, and Mg nanoparticles using laser ablation of magnesium in water and solvents

Energy Technology Data Exchange (ETDEWEB)

Phuoc, Tran X. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Howard, Bret. H. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Martello, Donald V. [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Soong, Yee [National Energy Technology Lab. (NETL), Pittsburgh, PA, (United States); Chyu, Minking K. [Univ. of Pittsburgh, PA (United States)

2008-11-01

Laser ablation of magnesium in deionized water (DW), solutions of DW and sodium dodecyl sulfate (SDS) with different concentrations, acetone and 2-propanol has been conducted. The results showed that ablation in acetone and 2-propanol yielded MgO and Mg nanocrystallites as isolated particles and agglomerated chains probably intermixed with organic residues resulting from the alteration/decomposition of the solvents under the high-energy conditions. Brucite-like Mg(OH)₂ particles were mainly produced by laser ablation of Mg in either DW or DW-SDS solutions. Ablation in DW yielded particles of fiber-like shapes having a diameter of about 5-10nm and length-as long as 150 nm. Materials produced in DW-SDS solutions were composed of various size and shape particles. Some had rough surfaces with irregular shapes. Small particles were about 20-30 nm and larger particles were about 120 nm. Particles with rodlike, triangular, and plate-like shapes were also observed.

Mg-MOF-74/MgF₂ Composite Coating for Improving the Properties of Magnesium Alloy Implants: Hydrophilicity and Corrosion Resistance.

Science.gov (United States)

Liu, Wei; Yan, Zhijie; Ma, Xiaolu; Geng, Tie; Wu, Haihong; Li, Zhongyue

2018-03-07

Surface modification on Mg alloys is highly promising for their application in the field of bone repair. In this study, a new metal-organic framework/MgF₂ (Mg-MOF-74/MgF₂) composite coating was prepared on the surface of AZ31B Mg alloy via pre-treatment of hydrofluoric acid and in situ hydrothermal synthesis methods. The surface topography of the composite coating is compact and homogeneous, and Mg-MOF-74 has good crystallinity. The corrosion resistance of this composite coating was investigated through Tafel polarization test and immersion test in simulated body fluid at 37 °C. It was found that Mg-MOF-74/MgF₂ composite coating significantly slowed down the corrosion rate of Mg alloy. Additionally, Mg-MOF-74/MgF₂ composite coating expresses super-hydrophilicity with the water contact angle of nearly 0°. In conclusion, on the basis of MgF₂ anticorrosive coating, the introduction of Mg-MOF-74 further improves the biological property of Mg alloys. At last, we propose that the hydrophilicity of the composite coating is mainly owing to the large number of hydroxyl groups, the high specific surface area of Mg-MOF-74, and the rough coating produced by Mg-MOF-74 particles. Hence, Mg-MOF-74 has a great advantage in enhancing the hydrophilicity of Mg alloy surface.

Effect of aqueous Si/Mg ratio and pH on the nucleation and growth of sepiolite at 25 °C

Science.gov (United States)

Baldermann, Andre; Mavromatis, Vasileios; Frick, Paula M.; Dietzel, Martin

2018-04-01

Sepiolite [Mg4Si6O15(OH)2·6H2O] is a trioctahedral 2:1 Mg-silicate that has been often used to reconstruct the evolution of sedimentary environments and facies in the geological record. To date, however, the reaction paths underlying sepiolite formation are poorly constrained and most of the existing models are based on empirical observations. In order to shed light on the mechanisms controlling the formation of this mineral phase, in the present study, sepiolite was precipitated at 25 ± 1 °C from modified seawater and MgCl2 solutions undersaturated with respect to brucite and amorphous silica. Although a suite of hydrous Mg-silicates, such as kerolite, saponite, stevensite and talc, were oversaturated in the solutions at a higher level relative to sepiolite at any time of reaction, poorly crystallized, aluminous sepiolite was the only precipitate after 91 days. The precipitated sepiolite [Mg3.4-3.8Al0.1-0.4)∑3.8-3.9(Si5.9-6.0Al0-0.1)O15(OH)2·nH2O] shares a number of structural and chemical similarities with natural sepiolite, such as a fibrous crystal shape and an atomic Si/(Si + Mg+Al) ratio of ∼0.61. The proposed reaction path for the formation of sepiolite is based on the temporal evolution of the chemical compositions of the experimental solution and solids: (i) Nucleation and growth of Al-sepiolite occurred during the first 8 days of the experimental runs via condensation and polymerization of Sisbnd OH tetrahedra onto Mg-Al-O-OH template sheets at a precipitation rate of ∼2.19 ± 0.01 × 10-10 mol s-1. (ii) At decreasing pH and in the absence of [Al]aq this intermediate phase transformed into aluminous sepiolite at a slower crystal growth rate of ∼1.08 ± 0.02 × 10-12 mol s-1. This finding explains the high abundances of sepiolite in highly alkaline, evaporitic, lacustrine and soil environments, where the growth rates of sepiolite are considered faster (10-11 to 10-10 mol s-1, Brady, 1992). We propose that (i) low rates of Mg2+ ion dehydration

Synthesis and spectroscopic studies of biologically active tetraazamacrocyclic complexes of Mn(II, Co(II, Ni(II, Pd(II and Pt(II

Directory of Open Access Journals (Sweden)

Monika Tyagi

2014-01-01

Full Text Available Complexes of Mn(II, Co(II, Ni(II, Pd(II and Pt(II were synthesized with the macrocyclic ligand, i.e., 2,3,9,10-tetraketo-1,4,8,11-tetraazacycoletradecane. The ligand was prepared by the [2 + 2] condensation of diethyloxalate and 1,3-diamino propane and characterized by elemental analysis, mass, IR and 1H NMR spectral studies. All the complexes were characterized by elemental analysis, molar conductance, magnetic susceptibility measurements, IR, electronic and electron paramagnetic resonance spectral studies. The molar conductance measurements of Mn(II, Co(II and Ni(II complexes in DMF correspond to non electrolyte nature, whereas Pd(II and Pt(II complexes are 1:2 electrolyte. On the basis of spectral studies an octahedral geometry has been assigned for Mn(II, Co(II and Ni(II complexes, whereas square planar geometry assigned for Pd(II and Pt(II. In vitro the ligand and its metal complexes were evaluated against plant pathogenic fungi (Fusarium odum, Aspergillus niger and Rhizoctonia bataticola and some compounds found to be more active as commercially available fungicide like Chlorothalonil.

Preparation of chitosan/MCM-41-PAA nanocomposites and the adsorption behaviour of Hg(II) ions

Science.gov (United States)

Fu, Yong; Huang, Yue; Hu, Jianshe

2018-03-01

A novel functional hybrid mesoporous composite material (CMP) based on chitosan and MCM-41-PAA was reported and its application as an excellent adsorbent for Hg(II) ions was also investigated. Innovatively, MCM-41-PAA was prepared by using diatomite and polyacrylic acid (PAA) with integrated polymer-silica hybrid frameworks, and then CMP was fabricated by introducing MCM-41-PAA to chitosan using glutaraldehyde as a cross-linking agent. The structure and morphology of CMP were characterized by X-ray diffraction, Fourier transform infrared spectra, thermogravimetric analysis, scanning electron microscopy and Brunauer-Emmett-Teller measurements. The results showed that the CMP possessed multifunctional groups such as -OH, -COOH and -NH2 with large specific surface area. Adsorption behaviour of Hg(II) ions onto CMP was fitted better by the pseudo-second-order kinetic model and the Langmuir model when the initial Hg(II) concentration, pH, adsorption temperature and time were 200 mg l-1, 4, 298 K and 120 min, respectively, as the optimum conditions. The corresponding maximum adsorption capacity could reach 164 mg g-1. According to the thermodynamic parameters determined such as free energy, enthalpy and entropy, the adsorption process of Hg(II) ions was spontaneous endothermic adsorption.

Effect of Mg content on microstructure and corrosion behavior of hot dipped Zn–Al–Mg coatings

Energy Technology Data Exchange (ETDEWEB)

Yao, Caizhen; Lv, Haibing [Research Centre of Laser Fusion, CAEP, P.O.Box 919-988-5, Mianyang, Sichuan 621900 (China); Zhu, Tianping [Department of Chemical and Materials Engineering, The University of Auckland, PB 92019, Auckland 1142 (New Zealand); Zheng, Wanguo [Research Centre of Laser Fusion, CAEP, P.O.Box 919-988-5, Mianyang, Sichuan 621900 (China); Yuan, Xiaodong, E-mail: xdyuan@caep.cn [Research Centre of Laser Fusion, CAEP, P.O.Box 919-988-5, Mianyang, Sichuan 621900 (China); Gao, Wei, E-mail: w.gao@auckland.ac.nz [Department of Chemical and Materials Engineering, The University of Auckland, PB 92019, Auckland 1142 (New Zealand)

2016-06-15

In this article, Zn–Al–Mg coatings were prepared by hot dipping method. The surface morphology, cross–section microstructure, microhardness, composition, corrosion behaviour of ZAM coatings were investigated by using X–ray diffraction (XRD), Optical microscope, Environmental scanning electron microscopy equipped with EDS (FESEM–EDS), Microhardness tester and Electrochemical analysis respectively. Corrosion test was also performed in a standard salt fog spray chamber. Microstructure studies indicates that Zn grain size was refined and eutectic areas at Zn grain boundary areas increased with increasing Mg content. ZA5M1.5 and ZA5M2 coatings have two distinct layers. Mg tends to exist in the outer layer while Al is in the inner layer. The inner layer is composed of Al{sub 5}Fe{sub 2}Zn{sub 0.4} intermetallic, which may to contribute to the microhardness. The outer layer is Zn grains surrounded by Zn–Mg etutectics, which may improve the corrosion resistance. The microhardness is more than 700 HV{sub 50g} for Al-rich layer and around 151 HV{sub 25g} for Mg-rich layer. The improved corrosion resistance of Zn–5%Al-1.5%Mg coating comes from the corrosion product of flocculent type simonkolleite, which prolongs the micro-path and impedes the movement of O{sub 2} and H{sub 2}O, ultimately retards the overall corrosion process. - Highlights: • Two-layer structured Zn–Al–Mg coatings were prepared by hot dipping method. • Mg exists in the outer layer while Al exists in the inner layer of Zn–Al–Mg coating. • Zn–Al–Mg coating has better protective ability than Zn and Zn–Al coatings. • The Mg-modified simonkolleite is the reason of the enhanced corrosion resistance.