Selective colorimetric NO(g) detection based on the use of modified gold nanoparticles using click chemistry

[EN] A new colorimetric system for NO(g) detection is described. The detection method is based on the aggregation of modified AuNPs through a Cu(I) catalyzed click reaction promoted by the in situ reduction of Cu(II) by NOWe acknowledge the Spanish Government (MAT2009-14564-C04-03 and MAT2012-38429-C04-02) for financial support. A. M. is grateful to the Spanish Government for a fellowship. SCSIE (Universidad de Valencia) is gratefully acknowledged for all the equipment employed.Marti, A.; Costero Nieto, AM.; Gaviña Costero, P.; Parra Álvarez, M. (2015). Selective colorimetric NO(g) detection based on the use of modified gold nanoparticles using click chemistry. Chemical Communications. 51(15):3077-3079. https://doi.org/10.1039/c4cc10149aS307730795115Nagano, T. (1999). Practical methods for detection of nitric oxide. Luminescence, 14(6), 283-290. doi:10.1002/(sici)1522-7243(199911/12)14:63.0.co;2-gL. J. 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Turn-on fluorescent probes for nitric oxide sensing based on the ortho-hydroxyamino structure showing no interference with dehydroascorbic acid. Chemical Communications, 50(27), 3579. doi:10.1039/c3cc49555hLv, X., Wang, Y., Zhang, S., Liu, Y., Zhang, J., & Guo, W. (2014). A specific fluorescent probe for NO based on a new NO-binding group. Chem. Commun., 50(56), 7499-7502. doi:10.1039/c4cc03540bSaha, K., Agasti, S. S., Kim, C., Li, X., & Rotello, V. M. (2012). Gold Nanoparticles in Chemical and Biological Sensing. Chemical Reviews, 112(5), 2739-2779. doi:10.1021/cr2001178Mayer, K. M., & Hafner, J. H. (2011). Localized Surface Plasmon Resonance Sensors. Chemical Reviews, 111(6), 3828-3857. doi:10.1021/cr100313vMartí, A., Costero, A. M., Gaviña, P., Gil, S., Parra, M., Brotons-Gisbert, M., & Sánchez-Royo, J. F. (2013). Functionalized Gold Nanoparticles as an Approach to the Direct Colorimetric Detection of DCNP Nerve Agent Simulant. 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A New Simple Chromo-fluorogenic Probe for NO2 Detection in Air

[EN] A new chromo-fluorogenic probe, consisting of a biphenyl derivative containing both a silylbenzyl ether and a N,N-dimethylamino group, for NO2 detection in the gas phase has been developed. A clear colour change from colourless to yellow together with an emission quenching was observed when the probe reacted with NO2. A limit of detection to the naked eye of about 0.1 ppm was determined and the system was successfully applied to the detection of NO2 in realistic atmospheric conditions.We thank the Spanish Government (MAT2012‐38429‐C04) and Generalitat Valenciana (PROMETEOII/2014/047) for support. SCSIE (Universidad de Valencia) is gratefully acknowledged for all the equipment employed. We thank Dr. A. Múñoz from the CEAM (Valencia‐Spain) for her help for the development of the measures in real environment.Juarez, LA.; Costero, AM.; Sancenón Galarza, F.; Martínez-Máñez, R.; Parra Álvarez, M.; Gaviña Costero, P. (2015). A New Simple Chromo-fluorogenic Probe for NO2 Detection in Air. Chemistry - A European Journal. 21(24):8720-8722. doi:10.1002/chem.201500608S87208722212

G 112-29 (=NLTT 18149), a Very Wide Companion to GJ 282 AB with a Common Proper Motion, Common Parallax, Common Radial Velocity and Common Age

We have made a search for common proper motion (CPM) companions to the wide binaries in the solar vicinity. We found that the binary GJ 282AB has a very distant CPM companion (NLTT 18149) at a separation s=1.09 \arcdeg. Improved spectral types and radial velocities are obtained, and ages determined for the three components. The Hipparcos trigonometric parallaxes and the new radial velocities and ages turn out to be very similar for the three stars, and provide strong evidence that they form a physical system. At a projected separation of 55733AU from GJ 282AB, NLTT 18149 ranks among the widest physical companions known.Comment: 13 pages, 3 figures, submmited to Ap

Composite Accretion Disk and White Dwarf Photosphere Analyses of the FUSE and HST Observations of EY Cygni

We explore the origin of FUSE and HST STIS far UV spectra of the dwarf nova, EY Cyg, during its quiescence using \emph{combined} high gravity photosphere and accretion disk models as well as model accretion belts. The best-fitting single temperature white dwarf model to the FUSE plus HST STIS spectrum of EY Cygni has T$_{eff} = 24,000$K, log $g = 9.0$, with an Si abundance of 0.1 x solar and C abundance of 0.2 x solar but the distance is only 301 pc. The best-fitting composite model consists of white dwarf with T$_{eff} = 22,000$K, log $g = 9$, plus an accretion belt with T$_{belt} = 36,000$K covering 27% of the white dwarf surface with V$_{belt} sin i = 2000$ km/s. The accretion belt contributes 63% of the FUV light and the cooler white dwarf latitudes contribute 37%. This fit yields a distance of 351 pc which is within 100 pc of our adopted distance of 450 pc. EY Cyg has very weak C {\sc iv} emission and very strong N {\sc v} emission, which is atypical of the majority of dwarf novae in quiescence. We also conducted a morphological study of the surroundings of EY Cyg using direct imaging in narrow nebular filters from ground-based telescopes. We report the possible detection of nebular material^M associated with EY Cygni. Possible origins of the apparently large N {\scv}/C {\sc iv} emission ratio are discussed in the context of nova explosions, contamination of the secondary star and accretion of nova abundance-enriched matter back to the white dwarf via the accretion disk or as a descendant of a precursor binary that survived thermal timescale mass transfer. The scenario involving pollution of the secondary by past novae may be supported by the possible presence of a nova remnant-like nebula around EY Cyg.Comment: To appear in AJ, Oct. 2004. 5 figures, including 2 color ones (2D pictures

The Expanding Nebular Remnant of the Recurrent Nova RS Ophiuchi (2006): II. Modeling of Combined Hubble Space Telescope Imaging and Ground-based Spectroscopy

We report Hubble Space Telescope imaging, obtained 155 and 449 days after the 2006 outburst of the recurrent nova RS Ophiuchi, together with ground-based spectroscopic observations, obtained from the Observatorio Astron\'omico Nacional en San Pedro M\'artir, Baja California, M\'exico and at the Observatorio Astrof\'isico Guillermo Haro, at Cananea, Sonora, M\'exico. The observations at the first epoch were used as inputs to model the geometry and kinematic structure of the evolving RS Oph nebular remnant. We find that the modeled remnant comprises two distinct co-aligned bipolar components; a low-velocity, high-density innermost (hour glass) region and a more extended, high-velocity (dumbbell) structure. This overall structure is in agreement with that deduced from radio observations and optical interferometry at earlier epochs. We find that the asymmetry observed in the west lobe is an instrumental effect caused by the profile of the HST filter and hence demonstrate that this lobe is approaching the observer. We then conclude that the system has an inclination to the line of sight of 39$^{+1}_{-10}$ degrees. This is in agreement with the inclination of the binary orbit and lends support to the proposal that this morphology is due to the interaction of the outburst ejecta with either an accretion disk around the central white dwarf and/or a pre-existing red giant wind that is significantly denser in the equatorial regions of the binary than at the poles. The second epoch HST observation was also modeled. However, as no spectra were taken at this epoch, it is more difficult to constrain any model. Nevertheless, we demonstrate that between the two HST epochs the outer dumbbell structure seems to have expanded linearly.Comment: 33 pages, 9 figures, 1 table, accepted for publication in Ap

Unconventional OFF–ON Response of a Mono(calix[4]arene)-Substituted BODIPY Sensor for Hg2+ through Dimerization Reversion

A new selective fluorogenic chemosensor for Hg2+, which combines a calixarene derivative with a BODIPY core as a fluorescent reporter, is described. The remarkable change in its fluorogenic properties in DMSO and CHCl3 has been analyzed. A study of its spectral properties on dilution, along with molecular modeling studies, allowed us to explain that this behavior involves the formation of a J-dimer, as well as how the sensing mechanism of Hg2+ proceeds

The Initial Mass Function of the Orion Nebula Cluster across the H-burning limit

We present a new census of the Orion Nebula Cluster (ONC) over a large field of view (>30'x30'), significantly increasing the known population of stellar and substellar cluster members with precisely determined properties. We develop and exploit a technique to determine stellar effective temperatures from optical colors, nearly doubling the previously available number of objects with effective temperature determinations in this benchmark cluster. Our technique utilizes colors from deep photometry in the I-band and in two medium-band filters at lambda~753 and 770nm, which accurately measure the depth of a molecular feature present in the spectra of cool stars. From these colors we can derive effective temperatures with a precision corresponding to better than one-half spectral subtype, and importantly this precision is independent of the extinction to the individual stars. Also, because this technique utilizes only photometry redward of 750nm, the results are only mildly sensitive to optical veiling produced by accretion. Completing our census with previously available data, we place some 1750 sources in the Hertzsprung-Russel diagram and assign masses and ages down to 0.02 solar masses. At faint luminosities, we detect a large population of background sources which is easily separated in our photometry from the bona fide cluster members. The resulting initial mass function of the cluster has good completeness well into the substellar mass range, and we find that it declines steeply with decreasing mass. This suggests a deficiency of newly formed brown dwarfs in the cluster compared to the Galactic disk population.Comment: 16 pages, 18 figures. Accepted for publication in The Astrophysical Journa

Isomerization and Redox Tuning: Reorganizing the Maya Blue Puzzle from Synthetic, Spectral, and Electrochemical Issues

[EN] A new approach to describe the composition of Maya blue (MB), an ancient organic- inorganic hybrid material, is presented. It is based on the analysis of attenuated total reflection-Fourier transform infrared (ATR-FTIR), Raman spectroscopy, UV-visible (vis) spectroscopic, and electrochemical data for indigo and dehydroindigo plus palygorskite hybrids, including a novel methodology using electrocatalytic effects on the oxygen reduction reaction. As a result, it is concluded that MB results from the tautomerization of indigo-to-indigo hemienol and the subsequent oxidation of these isomeric forms to dehydroindigo, all associated with the palygorskite clay framework, at temperatures above 100 degrees C. This model is also consistent with C-13 NMR data on indigo plus sepiolite hybrids. A consistent set of thermochemical parameters is obtained from ATR-FTIR, solid-state electrochemistry, and UV-vis diffuse reflectance spectra for the successive isomerization and redox tuning processes experienced by palygorskite-associated indigo.Projects PID2020-113022GB-I00 and RTI2018-100910-BC42, supported by MCIN/AEI/10.13039/501100011033 are gratefully acknowledged for all of the equipment employed. NMR was registered at the U26 facility of ICTS "NANBIOSIS" at the SCSIE of the Universitat of Valencia.Doménech-Carbó, A.; Costero, AM.; Gil Grau, S.; Montoya, N.; López-Carrasco, A.; Sáez, JA.; Arroyo, P.... (2021). Isomerization and Redox Tuning: Reorganizing the Maya Blue Puzzle from Synthetic, Spectral, and Electrochemical Issues. The Journal of Physical Chemistry. 125(47):26188-26200. https://doi.org/10.1021/acs.jpcc.1c0793226188262001254