A census of variability in globular cluster M 68 (NGC 4590)

Kains, N.,Arellano Ferro, A.,Figuera Jaimes, R.,Bramich, D. M.,Skottfelt, J.,Jørgensen, U. G.,Tsapras, Y.,Street, R. A.,Browne, P.,Dominik, M.,Horne, K.,Hundertmark, M.,Ipatov, S.,Snodgrass, C.,Steele EDP Sciences 2015 Astronomy and astrophysics Vol.578 No.-

<P>Aims. We analyse 20 nights of CCD observations in the V and I bands of the globular cluster M?68 (NGC 4590) and use them to detect variable objects. We also obtained electron-multiplying CCD (EMCCD) observations for this cluster in order to explore its core with unprecedented spatial resolution from the ground. Methods. We reduced our data using difference image analysis to achieve the best possible photometry in the crowded field of the cluster. In doing so, we show that when dealing with identical networked telescopes, a reference image from any telescope may be used to reduce data from any other telescope, which facilitates the analysis significantly. We then used our light curves to estimate the properties of the RR Lyrae (RRL) stars in M?68 through Fourier decomposition and empirical relations. The variable star properties then allowed us to derive the cluster’s metallicity and distance. Results. M?68 had 45 previously confirmed variables, including 42 RRL and 2 SX Phoenicis (SX Phe) stars. In this paper we determine new periods and search for new variables, especially in the core of the cluster where our method performs particularly well. We detect 4 additional SX Phe stars and confirm the variability of another star, bringing the total number of confirmed variable stars in this cluster to 50. We also used archival data stretching back to 1951 to derive period changes for some of the single-mode RRL stars, and analyse the significant number of double-mode RRL stars in M?68. Furthermore, we find evidence for double-mode pulsation in one of the SX Phe stars in this cluster. Using the different classes of variables, we derived values for the metallicity of the cluster of [Fe/H] = −2.07 ±0.06 on the ZW scale, or −2.20 ±0.10 on the UVES scale, and found true distance moduli μ0 = 15.00±0.11 mag (using RR0 stars), 15.00 ± 0.05 mag (using RR1 stars), 14.97 ±0.11 mag (using SX Phe stars), and 15.00±0.07 mag (using the MV–[Fe/H] relation for RRL stars), corresponding to physical distances of 10.00 ±0.49, 9.99±0.21, 9.84 ±0.50, and 10.00 ±0.30 kpc, respectively. Thanks to the first use of difference image analysis on time-series observations of M?68, we are now confident that we have a complete census of the RRL stars in this cluster.</P>

A SUB-SATURN MASS PLANET, MOA-2009-BLG-319Lb

Miyake, N.,Sumi, T.,Dong, Subo,Street, R.,Mancini, L.,Gould, A.,Bennett, D. P.,Tsapras, Y.,Yee, J. C.,Albrow, M. D.,Bond, I. A.,Fouqué,, P.,Browne, P.,Han, C.,Snodgrass, C.,Finet, F.,Furusawa, K IOP Publishing 2011 The Astrophysical journal Vol.728 No.2

<P>We report the gravitational microlensing discovery of a sub-Saturn mass planet, MOA-2009-BLG-319Lb, orbiting a K-or M-dwarf star in the inner Galactic disk or Galactic bulge. The high-cadence observations of the MOA-II survey discovered this microlensing event and enabled its identification as a high-magnification event approximately 24 hr prior to peak magnification. As a result, the planetary signal at the peak of this light curve was observed by 20 different telescopes, which is the largest number of telescopes to contribute to a planetary discovery to date. The microlensing model for this event indicates a planet-star mass ratio of q = (3.95 +/- 0.02) x 10(-4) and a separation of d = 0.97537 +/- 0.00007 in units of the Einstein radius. A Bayesian analysis based on the measured Einstein radius crossing time, t(E), and angular Einstein radius,theta(E), along with a standard Galactic model indicates a host star mass of M-L = 0.38(-0.18)(+0.34) M-circle dot and a planet mass of M-p = 50(-24)(+44)M(circle plus), which is half the mass of Saturn. This analysis also yields a planet-star three-dimensional separation of a = 2.4(-0.6)(+1.2) AU and a distance to the planetary system of D-L = 6.1(-1.2)(+1.1) kpc. This separation is similar to 2 times the distance of the snow line, a separation similar to most of the other planets discovered by microlensing.</P>

MOA-2010-BLG-073L: AN M-DWARF WITH A SUBSTELLAR COMPANION AT THE PLANET/BROWN DWARF BOUNDARY

Street, R. A.,Choi, J.-Y.,Tsapras, Y.,Han, C.,Furusawa, K.,Hundertmark, M.,Gould, A.,Sumi, T.,Bond, I. A.,Wouters, D.,Zellem, R.,Udalski, A.,Snodgrass, C.,Horne, K.,Dominik, M.,Browne, P.,Kains, N.,Br IOP Publishing 2013 The Astrophysical journal Vol.763 No.1

<P>We present an analysis of the anomalous microlensing event, MOA-2010-BLG-073, announced by the Microlensing Observations in Astrophysics survey on 2010 March 18. This event was remarkable because the source was previously known to be photometrically variable. Analyzing the pre-event source light curve, we demonstrate that it is an irregular variable over timescales >200 days. Its dereddened color, (V - I)(S),(0), is 1.221 +/- 0.051 mag, and from our lens model we derive a source radius of 14.7 +/- 1.3 R-circle dot, suggesting that it is a red giant star. We initially explored a number of purely microlensing models for the event but found a residual gradient in the data taken prior to and after the event. This is likely to be due to the variability of the source rather than part of the lensing event, so we incorporated a slope parameter in our model in order to derive the true parameters of the lensing system. We find that the lensing system has a mass ratio of q = 0.0654 +/- 0.0006. The Einstein crossing time of the event, t(E) = 44.3 +/- 0.1 days, was sufficiently long that the light curve exhibited parallax effects. In addition, the source trajectory relative to the large caustic structure allowed the orbital motion of the lens system to be detected. Combining the parallax with the Einstein radius, we were able to derive the distance to the lens, D-L = 2.8 +/- 0.4 kpc, and the masses of the lensing objects. The primary of the lens is an M-dwarf with M-L,M-1 = 0.16 +/- 0.03 M-circle dot, while the companion has M-L,M-2 = 11.0 +/- 2.0 M-J, putting it in the boundary zone between planets and brown dwarfs.</P>

Comparative adsorption–regeneration performance for newly developed carbonaceous adsorbent

H.M.A. Asghar,S.N. Hussain,N.W. Brown,E.P.L. Roberts 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.69 No.-

A proprietary adsorbent material called Nyex 1000 was developed by the Arvia Technology Ltd. (UK based waste water treatment company). Nyex 1000 was being employed for a number of commercial applications dealing with the removal of organic contaminants from industrial effluents. This adsorbent material had small adsorptive capacity. With the aim to address small adsorptive capacity, a new graphite based adsorbent material was developed. The particle design was accomplished through successive chemical, thermal and mechanical treatments of raw graphite material (natural large flake graphite, to be called here as NLFG). The chemical treatment of the NLFG was carried out through electrochemical intercalation using dilute (50%) sulfuric acid in an electrochemical cell. Chemically treated NLFG then went through thermal treatment at 850 °C and followed by mechanical treatments consisting of compression (4536 kgf cm−2) and chopping at 18,000 rpm for 30 s. The developed adsorbent material, (exfoliated compacted graphite, to be called here as ECG) and NLFG were characterized using state of the art techniques including SEM, BET surface area, XRD, Zeta potential, Boehm surface titration, bed electrical conductivity and laser size analysis. The characterization results showed significant increase in internal specific surface area from 1 to 17 m2 g−1. It was attributed to the development of partially porous particle surface verified by SEM results. The XRD, Boehm surface titration, Zeta potential results endorsed the associated chemical and physical changes appeared in the composition of the NLFG as a result of chemical, thermal and mechanical treatments. Adsorption-regeneration studies were conducted using developed ECG and existing Nyex 1000 materials. The pollutants used for adsorption–regeneration studies were acid violet 17, phenol, humic acid, ethane thiol and methyl propane thiol dissolved in aqueous solution. The results were compared and it was found that ECG showed significantly improved adsorption capacity with many folds. Both adsorbent materials, ECG and Nyex 1000 delivered 100% electrochemical regeneration efficiencies.

Synthesis of electrically conducting composite adsorbents for wastewater treatment using adsorption & electrochemical regeneration

H.M.A. Asghar,S.N. Hussain,N.W. Brown,E.P.L. Roberts 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.3

Electrically conducting adsorbent materials called NyexTM 1000 & 2000 have already been reported withcomparatively low adsorption capacity for various organic, biologically non-degradable and toxiccompounds. Two composite adsorbents called CA1 & CA2 were synthesized using synthetic graphite-carbon black and expanded graphite-carbon black respectively. The aim of developing the newadsorbents was to increase the adsorption capacity along with good electrical properties. The developedadsorbents were characterized using N2 adsorption for specific surface area, Boehm surface titration forsurface chemistry, bed electrical conductivity, laser size analyzer for average particle size, and scanningelectron microscope (SEM) for particle morphology and shape. Then both the composite adsorbents weretested for the adsorption of acid violet 17 followed by an electrochemical regeneration. The adsorptionstudy revealed that both the adsorbents had almost similar kinetic behavior with a significant increase inadsorption capacity for acid violet 17 (300 & 26 mg g-1 respectively) when compared with theadsorption capacity of previously developed electrically conducting materials called NyexTM 1000 &2000 (3.5 and 9 mg g-1 respectively). The composite adsorbent CA2 was successfully electrochemicallyregenerated by passing an electric charge of 138 C g-1 at a current density of 14 mA cm-2 for a treatmenttime of 60 min, whereas, the composite adsorbent CA1 could not be regenerated successfully. Theregeneration efficiencies of CA2 were obtained at around 120% during five adsorption–regenerationcycles. The amount of actual charge passed of 138 C g-1 for achieving 100% regeneration efficiency wasfound to be similar with stoichiometrically calculated amount of charge. The amount of electrical energyrequired to oxidize each mg of adsorbed acid violet onto CA2 (24 J mg-1) was found to be significantlylower to that of NyexTM 1000 & 2000 adsorbents (52 J mg-1 & 32 J mg-1 respectively).

International comparison CCQM-K119 liquefied petroleum gas

Brewer, P J,Downey, M L,Atkins, E,Brown, R J C,Brown, A S,Zalewska, E T,van der Veen, A M H,Smeulders, D E,McCallum, J B,Satumba, R T,Kim, Y D,Kang, N,Bae, H K,Woo, J C,Konopelko, L A,Popova, T A,Mesh IOP 2018 Metrologia Vol.55 No.-

<P></P> <P>Liquefied hydrocarbon mixtures with traceable composition are required in order to underpin measurements of the composition and other physical properties of LPG (liquefied petroleum gas), thus meeting the needs of an increasingly large industrial market.</P> <P>This comparison aims to assess the analytical capabilities of laboratories for measuring the composition of a Liquid Petroleum Gas (LPG) mixture when sampled in the liquid phase from a Constant Pressure Cylinder. Mixtures contained ethane, propane, propene, i-butane, n-butane, but-1-ene and i-pentane with nominal amount fractions of 2, 71, 9, 4, 10, 3 and 1 cmol mol<SUP>−1</SUP> respectively.</P> <H2>Main text</H2> <P> To reach the main text of this paper, click on <A HREF='https://www.bipm.org/utils/common/pdf/final_reports/QM/K119/CCQM-K119.pdf'>Final Report</A>. Note that this text is that which appears in Appendix B of the BIPM key comparison database <A HREF='http://kcdb.bipm.org/'>kcdb.bipm.org/</A>.</P> <P>The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).</P>

Highly Porous Silica Nanoaerogels for Ultrafast Nonlinear Optical Applications

Seo, Jae Tae,Ma, S.M.,Lee, K.,Brown, H.,Jackson, A.,Skyles, T.,Cubbage, N.M.,Tabibi, B.,Yoo, K.P.,Kim, Suk Young,Jung, S.S.,Namkung, M. Trans Tech Publications, Ltd. 2005 Key Engineering Materials Vol.287 No.-

<P>Highly porous silica nanoaerogels with low apparent density of ~0.1 g/cm3 and ~0.07 g/cm3 were synthesized through two-step sol-gel processing and low temperature supercritical fluid drying. The nonlinear refraction (γ) of silica nanoaerogels was estimated to be ~ -3.4 x 10-16 m2/W for ~0.1 g/cm3 and ~0.07 g/cm3 apparent densities with a signal-beam femtosecond z-scan spectroscopy. The third-order nonlinear refraction coefficient of nanostructure silica nanoaerogels was almost four orders larger than that of bulk silica materials. The large nonlinearrefraction with high nonlinear figure of merit (γ/βλ, β~2×10-10 m/W for 0.07 g/cm3 apparent density, β~6×10-10 m/W for 0.1 g/cm3 apparent density, λ~0.775 µm) is an ideal optical property for nonlinear applications of homeland security, battlefield enhancement, and industrial uses.</P>

Classroom controversy as an antidote for the sponge model of learning

N.M. Browne,M.L. Keeley-Vasudeva 대한사고개발학회 1993 The International Journal of Creativity & Problem Vol.3 No.1

When asked to spell out major hurdles they face as teachers, professors often bemoan the sea of passivity they must face each day. The promise of classroom controversy lies in its ability to arouse the passive learner, while contributing to important generic and developmental skills. Specifically, choosing curriculum materials and teaching behaviors that promote controversy facilitates critical thinking and the formation of reasonable commitments. Controversies serve as the rock that shatters the calm, impassive surface appearance of students accustomed to their roles as sponges.

Overcoming student resistance to critical thinking

N.M. Browne,N.K.Kubasek 대한사고개발학회 1993 The International Journal of Creativity & Problem Vol.3 No.1

Cavity enhanced spectroscopy for measurement of nitrogen oxides in the Anthropocene: results from the Seoul tower during MAPS 2015

Brown, S.,An, H.,Lee, M.,Park, J. H.,Lee, S. D.,Fibiger, D.,McDuffie, E.,Dube, W.,Wagner, N.,Min, K. E. Royal Society of Chemistry 2017 Faraday discussions Vol.200 No.-