Abundances of Recently Discovered Planetary Nebulae Towards the Galactic Bulge

In this work we report spectrophotometric observations of a planetary nebula sample towards the galactic bulge. A total of 45 PNe was observed and their physical parameters (electron density and temperature) were derived. Ionic abundances were calculated using a three-level atom model and abundances were derived through ionisation correction factors. Results show low abundance objects at high galactic latitudes, indicating a possible vertical gradient inside the bulge. A few objects with low N/O ratio were found, which could originated from old, low mass progenitors

Globular Clusters: DNA of Early-Type galaxies?

This paper explores if the mean properties of Early-Type Galaxies (ETG) can be reconstructed from "genetic" information stored in their GCs (i.e., in their chemical abundances, spatial distributions and ages). This approach implies that the formation of each globular occurs in very massive stellar environments, as suggested by some models that aim at explaining the presence of multi-populations in these systems. The assumption that the relative number of globular clusters to diffuse stellar mass depends exponentially on chemical abundance, [Z/H], and the presence of two dominant GC sub-populations blue and red, allows the mapping of low metallicity halos and of higher metallicity (and more heterogeneous) bulges. In particular, the masses of the low-metallicity halos seem to scale up with dark matter mass through a constant. We also find a dependence of the globular cluster formation efficiency with the mean projected stellar mass density of the galaxies within their effective radii. The analysis is based on a selected sub-sample of galaxies observed within the ACS Virgo Cluster Survey of the {\it Hubble Space Telescope}. These systems were grouped, according to their absolute magnitudes, in order to define composite fiducial galaxies and look for a quantitative connection with their (also composite) globular clusters systems. The results strengthen the idea that globular clusters are good quantitative tracers of both baryonic and dark matter in ETGs.Comment: 20 pages, 28 figures and 5 table

Pinholes May Mimic Tunneling

Interest in magnetic-tunnel junctions has prompted a re-examination of tunneling measurements through thin insulating films. In any study of metal-insulator-metal trilayers, one tries to eliminate the possibility of pinholes (small areas over which the thickness of the insulator goes to zero so that the upper and lower metals of the trilayer make direct contact). Recently, we have presented experimental evidence that ferromagnet-insulator-normal trilayers that appear from current-voltage plots to be pinhole-free may nonetheless in some cases harbor pinholes. Here, we show how pinholes may arise in a simple but realistic model of film deposition and that purely classical conduction through pinholes may mimic one aspect of tunneling, the exponential decay in current with insulating thickness.Comment: 9 pages, 3 figures, plain TeX; submitted to Journal of Applied Physic

Chemical evolution of the galactic bulge: single and double infall models

Recent work has produced a wealth of data concerning the chemical evolution of the galactic bulge, both for stars and nebulae. Present theoretical models generally adopt a limited range of such constraints, frequently using a single chemical element (usually iron), which is not enough to describe it unambiguously. In this work, we take into account constraints involving as many chemical elements as possible, basically obtained from bulge nebulae and stars. Our main goal is to show that different scenarios can describe, at least partially, the abundance distribution and several distance-independent correlationss for these objects. Three classes of models were developed. The first is a one-zone, single-infall model, the second is a one-zone, double-infall model and the third is a multizone, double infall model. We show that a one-zone model with a single infall episode is able to reproduce some of the observational data, but the best results are achieved using a multizone, double infall model.Comment: 15 pages, 7 figures, accepted for publication in Baltic Astronomy, Latex, uses baltlat5.sty, epsfig.st

Development of a robust HS-SPME-GC-MS method for the analysis of solid food samples. Analysis of volatile compounds in fresh raw beef of differing lipid oxidation degrees

This work presents a headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) method for the analysis of solid food samples in extended experiments. The final procedure was used to quantify 30 volatile compounds in fresh beef. The strategy adds robustness to the classic SPME methods for solid samples, by including a control solution that solves several challenges. The control solution contained one representative compound for each studied family of beef, and two internal standards. Response factors were calculated for each family, and were subsequently applied to every compound belonging to the same family. This strategy allowed control of the quantification procedure even when the fibre, column or control solution changed. Repeatability and reproducibility had relative standard deviation values below 17%, except for phenylacetaldehyde, (E)-2-nonenal and (E, Z)-2, 4-decadienal. Although the method described here was applied to animal products, it has also been successfully used to distinguish between samples from different lipid oxidation stabilities

Rational exploitation of a granite outcrop

[Abstract] This piece analizes the possibilities of mining exploitation in a little outcrop of rOSfl granite. The zone has been researched, recognizing the main structural discontinuities, and characterizing the rock mass by the geomechanic classificationofBARTON. Two core drilling have been made to study the evolution ofthe deeper bed. The volume ofthe bed has been calculated by geometric calculation in the researched area. The theories ofCASTAING and RABU have been developed to estimate the useful volume of the bed for a minimum block size of 1 m3. We have implerríented a computer program in base ofEXCEL 4.0. The result is a useful volume of 51.67 %. By the application of the reduction coefficients ofsterility and irregularity, the maximum estimated efficiency of the exploitation is 33 %

The populations of planetary nebulae in the direction of the Galactic bulge

We have observed 44 planetary nebulae (PNe) in the direction of the Galactic bulge, and merged our data with published ones. We have distinguished, in the merged sample of 164 PNe, those PNe most likely to prtain physically to the Galactic bulge and those most likely to belong to the Galactic disk. We have determined the chemical composition of all the 164 objects in a coherent way. We looked for stellar emission features and discovered 14 new [WR] stars and 15 new weak emission line central stars. The analyzed data led us to the following conclusions: (1) The spectral type distribution of [WR] stars is very different in the bulge and in the disk of the Galaxy. However, the observed distributions are strongly dependent on selection effects. (2) The proportion of [WR] PNe is significantly larger in the bulge than in the disk. (3) The oxygen abundances in [WR] stars do no appear to be significantly affected by nucleosynthesis and mixing in the progenitors. (4) The O/H gradient of the Galactic disk PNe population flattens in the most internal parts of the Galaxy. (5) The median oxygen abundance in the bulge PN population is larger by 0.2 dex than in the disk population seen in the direction of the bulge. (6) Bulge PNe with smaller O/H tend to have smaller radial velocities. (7) The oxygen abundance distribution of bulge PNe is similar in shape to that of the metallicity distribution of bulge giants, but significantly narrower. (8) The location of SB 32 (PN G 349.7-09.1) in the (V_lsr, l_II) diagram and its low oxygen abundance argues that it probably belongs to the halo population.Comment: 14 pages, 16 figures. Accepted for publication in A&

Abrogation of mercuric chloride-induced nephritis in the Brown Norway rat by treatment with antibodies against TNFα

HgCl2 induces an autoimmune disease in the Brown Norway rat characterized by synthesis of autoantibodies (mainly, anti-GBM Abs), severe proteinuria and interstitial nephritis. Also, HgCl2- injected rats develop glomerular cell infiltrates consisting of ED1+ cells (monocyte/macrophage), starting on day 4 and reaching a maximum on day 8. Treatment with anti-TNF-α antiserum had preventative effects as it reduced the urinary protein levels to close to the normal range and also blocked the influx of inflammatory cells in the renal glomeruli and interstitium, but circulating anti-GBM and lineal glomerular IgG deposits were unmodified. In addition, whole isolated glomeruli from HgCl2-induced nephritis secreted TNF-α commencing on day 8, being maximally detected on day 11 and preceding, between 2 to 3 days, the development of proteinuria. The administration of anti-TNF-α antiserum or anti-α4 integrin mAb completely abrogated the synthesis of TNF-α in glomeruli isolated from the respective treated groups of animals, in addition to the proteinuria. Taken together our results confirm that TNF-α plays an important role in the induction and development of HgCl2-induced nephritis and highlights the pathogenic importance of the local release of TNF in those renal diseases in which prominent glomerular macrophage accumulation is a constant feature

High-Valent Pyrazolate-Bridged Platinum Complexes: A Joint Experimental and Theoretical Study

Complexes {Pt(C^C*)(µ-pz)}2] (HC^C*A= 1-(4-(ethoxycarbonyl)phenyl)-3-methyl-1H-imidazol-2-ylidene 1a, HC^C*B= 1-phenyl-3-methyl-1H-imidazol-2-ylidene 1b) react with methyl iodide (MeI) at room temperature in the dark to give compounds {PtIV(C^C*)Me(µ-pz)}2(µ-I)]I (C^C*A2a, C^C*B2b). The reaction of 1a with benzyl bromide (BnBr) in the same conditions afforded Br(C^C*A)PtIII(µ-pz)2PtIII(C^C*A)Bn] (5a), which by heating in BnBr(l) became {PtIV(C^C*A)Bn(µ-pz)}2(µ-Br)]Br (6a). Experimental investigations and density functional theory (DFT) calculations on the mechanisms of these reactions from 1a revealed that they follow a SN2 pathway in the two steps of the double oxidative addition (OA). Based on the DFT investigations, species such as (C^C*A)PtIII(µ-pz)2PtIII(C^C*A)R]X (RX = MeI Int-Me, BnBr Int-Bn) and (C^C*A)PtII(µ-pz)2PtIV(C^C*A)(R)X] (RX = MeI Int'-Me, BnBr Int'-Bn) were proposed as intermediates for the first and the second OA reactions, respectively. In order to put the mechanisms on firmer grounds, Int-Me was prepared as (C^C*A)PtIII(µ-pz)2PtIII(C^C*A)Me]BF4(3a') and used to get I(C^C*A)PtIII(µ-pz)2PtIII(C^C*A)Me](4a), (C^C*A)PtII(µ-pz)2PtIV(C^C*A)(Me)I](Int'-Me), and {PtIV(C^C*)Me(µ-pz)}2(µ-I)]BF4(2a'). The single-crystal X-ray structures of 2a, 2b, 3a', and 5a along with the mono- and bi-dimensional 1H and 195Pt{1H} NMR spectra of all the named species allowed us to compare structural and spectroscopic data for high-valent complexes with the same core {Pt(C^C*)(µ-pz)}2] but different oxidation states. © 2022 American Chemical Society. All rights reserved