Context. The Galactic H ii region NGC 2579 has stayed undeservedly unexplored due to identification problems which persisted until recently. Both NGC 2579 and its companion ESO 370-9 have been misclassified as planetary or reflection nebula, confused with each other and with other objects. Due to its high surface brightness, high excitation, angular size of few arcminutes and relatively low interstellar extinction, NGC 2579 is an ideal object for investigations in the optical range. Located in the outer Galaxy, NGC 2579 is an excellent object for studying the Galactic chemical abundance gradients. Aims. To present the first comprehensive observational study on the nebular and stellar properties of NGC 2579 and ESO 370-9, including the determination of electron temperature, density structure, chemical composition, kinematics, distance, and the identification and spectral classification of the ionizing stars, and to discuss the nature of ESO 370-9. Methods. Long slit spectrophotometric data in the optical range were used to derive the nebular electron temperature, density and chemical abundances and for the spectral classification of the ionizing star candidates. Hα and UBV CCD photometry was carried out to derive stellar distances from spectroscopic parallax and to measure the ionizing photon flux. Results. The chemical abundances of He, N, O, Ne, S, Cl, and Ar were obtained. Maps of electron density and radial velocity with a spatial resolution of 5 × 5 were composed from long slit spectra taken at different declinations. Three O stars classified as O5 V, O6.5 V, and O8 V were found responsible for the ionization of NGC 2579, while ESO 370-9 is ionized by a single O8.5 V star. The estimated mass of ionized gas of ≈25 M indicates that ESO 370-9 is not a planetary nebula, but a small H ii region. A photometric distance of 7.6 ± 0.9 kpc and a kinematic distance of 7.4 ± 1.4 kpc were obtained for both objects. At the galactocentric distance of 12.8 ± 0.7 kpc, NGC 2579 is one of the most distant Galactic H ii regions for which direct abundance determinations have been accomplished. Key words. ISM: H ii regions -ISM: planetary nebulae: general IntroductionDue to observational difficulties, the knowledge acquisition in many research areas of astrophysics has still relied largely on data obtained from a small group of characteristic objects. This is certainly the case of the optical studies of Galactic H ii regions. In this field, the Orion Nebula is by far the most studied object. In fact, the number of papers on this object is comparable to the total number of optical studies of all other Galactic H ii regions. Even the standard procedure of measuring the electron temperature in Galactic H ii regions from optical emission line ratios, such as [O iii] (λ4959 + λ5007)/λ4363 and [N ii] (λ6548 + λ6584)/λ5755, until now could only be accomplished in a small sample of a dozen or so objects. So, the addition of new members to the selected list of well studied (or easy to observe) objects is welcome, especially becaus...

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Aims. We attempt to identify the ionising stars and to determine the photometric distances of nine southern Galactic H ii regions.Methods. We carried out optical spectroscopy and UBV photometry of the stellar content of these objects. The distance of individual stars were obtained by spectroscopic parallax. To avoid using a fixed value for the total-to-selective extinction ratio R V , the reddening A V was determined directly by the colour-difference approach by comparing our V apparent magnitudes and the JHK magnitudes from the 2MASS survey with the intrinsic colour indices. Results. As types O or B, we classified 24 of the 31 stars for which optical spectra were obtained. In particular, we identified two new O stars, one in RCW 98 and the other in RCW 99. The values of reddening obtained correspond to a mean R V = 3.44, which is about 10% higher than the value found for field stars. For three of the H ii regions studied (Bran 186, NGC 2626, and RCW 32), the distance estimates (with errors from 25% to 50%) were based on the data obtained for only one star. For the other six objects (NGC 3503, NGC 6334, RCW 55, RCW 87, RCW 98, and RCW 99), we obtained more precise photometric distances (with a mean error of ≈18%) calculated to be the median of the parallax distances obtained for two to six different stars in each nebulae. The parallax distances of individual stars belonging to a given nebula were similar to each other, with internal errors smaller than 5%, as a consequence of the method used to derive the reddening correction A V . The distance of 1.23 ± 0.30 kpc obtained for RCW 87 disagrees with the value of 7.6 kpc previously found. Conclusions. The dispersion in individual distance estimates for stars in a given nebula can be significantly reduced by calculating the reddening A V from a comparison between the V and the 2MASS JHK magnitudes instead of using A V = R V E(B − V) with a fixed value for R V . Therefore, more precise distances can be calculated with our proposed method.

The aim of the present study was to evaluate the possible effects of zinc chloride against the gastrointestinal lesions caused by oral administration of ethanol in rats. Rats were divided into five groups, namely, saline, ethanol, zn, zn+ethanol and ethanol+zn. Ethanol 70% (2 mL/kg) was administered by gavage in 36 h fasted rats. Zinc chloride (27 mg/kg, ~13 mg/kg of zinc) was given by gavage 1h before or 1h after the administration of ethanol. Oral administration of ethanol consistently induced damage in the rat glandular stomach and intestine. Zinc did not demonstrate effect per se and significantly reduced gastrointestinal lesions when administered either before or after lesion induction. Ethanol induced enhancement of thiobarbituric acid reactive substance and reactive species levels, diminished the ascorbic acid and total protein SH content as well as superoxide dismutase and catalase activity in stomach and intestine of rats. Zinc treatment prevented and reversed these alterations induced by ethanol. Stomach and intestine of rats treated with zinc presented higher zinc content than the tissues of rats treated only with ethanol. Non-protein SH content was not altered by any treatment. Results suggested that the gastrointestinal protective effect of zinc in this experimental model could be due to its antioxidant effect.

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This study evaluated the effects of HgCl2 on renal parameters in nonlactating and lactating rats and their pups, as well as the preventive role of ZnCl2 . Rats received 27 mg kg(-1) ZnCl2 for five consecutive days and 5 mg kg(-1) HgCl2 for five subsequent days (s.c.). A decrease in δ-aminolevulinic acid dehydratase (δ-ALA-D) activity in the blood and an increase in urine protein content in renal weight as well as in blood and urine Hg levels were observed in lactating and nonlactating rats from Sal-Hg and Zn-Hg groups. ZnCl2 prevented partially the δ-ALA-D inhibition and the proteinuria in nonlactating rats. Renal Hg levels were increased in all HgCl2 groups, and the ZnCl2 exposure potentiated this effect in lactating rats. Nonlactating rats exposed to HgCl2 exhibited an increase in plasma urea and creatinine levels, δ-ALA-D activity inhibition and histopathological alterations (necrosis, atrophic tubules and collagen deposition) in the kidneys. ZnCl2 exposure prevented the biochemical alterations. Hg-exposed pups showed lower body and renal weight and an increase in the renal Hg levels. In conclusion, mercury-induced nephrotoxicity differs considerably between lactating and nonlactating rats. Moreover, prior exposure with ZnCl2 may provide protection to individuals who get exposed to mercury occupationally or accidentally.

This study investigated the toxicity of rats exposed to lead acetate (AcPb) during the second phase of brain development (8-12 days postnatal) in hematological and cerebral parameters. Moreover, the preventive effect of zinc chloride (ZnCl) and N-acetylcysteine (NAC) was investigated. Pups were injected subcutaneously with saline (0.9% NaCl solution), ZnCl (27 mg/kg/day), NAC (5 mg/kg/day) or ZnCl plus NAC for 5 days (3rd-7th postnatal days), and with saline (0.9% NaCl solution) or AcPb (7 mg/kg/day) in the five subsequent days (8th-12th postnatal days). Animals were sacrificed 21 days after the last AcPb exposure. Pups exposed to AcPb presented inhibition of blood porphobilinogen-synthase (PBG-synthase) activity without changes in hemoglobin content. ZnCl pre-exposure partially prevented PBG-synthase inhibition. Regarding neurotoxicity biomarkers, animals exposed to AcPb presented a decrease in cerebrum acetylcholinesterase (AChE) activity and an increase in Pb accumulation in blood and cerebrum. These changes were prevented by pre-treatment with ZnCl, NAC, and ZnCl plus NAC. AcPb exposure caused no alteration in behavioral tasks. In short, results show that AcPb inhibited the activity of two important enzymatic biomarkers up to 21 days after the end of the exposure. Moreover, ZnCl and NAC prevented the alterations induced by AcPb.

Context. The existence and origin of large spatial temperature fluctuations in H ii regions and planetary nebulae are assumed to explain the differences between the heavy element abundances inferred from collisionally excited and recombination lines, although this interpretation remains significantly controversial.Aims. We investigate the spatial variation in electron temperature inside NGC 346, the brightest H ii region in the Small Magellanic Cloud.Methods. Long slit spectrophotometric data of high signal-to-noise were employed to derive the electron temperature from measurements derived from localized observations of the [O iii](λ4959 + λ5007)/λ4363 ratio in three directions across the nebula.Results. The electron temperature was estimated in 179 areas of 5 × 1. 5 of size distributed along three different declinations. A largely homogeneous temperature distribution was found with a mean temperature of 12 269 K and a dispersion of 6.1%. After correcting for pure measurements errors, a temperature fluctuation on the plane of the sky of t 2 s = 0.0021 (corresponding to a dispersion of 4.5%) was obtained, which indicates a 3D temperature fluctuation parameter of t 2 ≈ 0.008. A large scale gradient in temperature of the order of −5.7 ± 1.3 K arcsec −1 was found. Conclusions. The magnitude of the temperature fluctuations observed agrees with the large scale variations in temperature predicted by standard photoionization models, but is too small to explain the abundance discrepancy problem. However, the possible existence of small spatial scale temperature variations is not excluded.