Revised physical elements of the astrophysically important O9.5+O9.5V eclipsing binary system Y Cyg

Thanks to its long and rich observational history and rapid apsidal motion, the massive eclipsing binary Y Cyg represents one of the cornestones to critical tests of stellar evolution theory for massive stars. Yet, the determination of the basic physical properties is less accurate than it could be given the existing number of spectral and photometric observations. Our goal is to analyze all these data simultaneously with the new dedicated series of our own spectral and photometric observations from observatories widely separated in longitude. We obtained new series of UBV observations at three observatories separated in local time to obtain complete light curves of Y Cyg for its orbital period close to 3 days. This new photometry was reduced and carefully transformed to the standard UBV system using the HEC22 program. We also obtained new series of red spectra secured at two observatories and re-analyzed earlier obtained blue electronic spectra. Our analyses provide the most accurate so far published value of the apsidal period of 47.805 +/- 0.030 yrs and the following physical elements: M1=17.72+/-0.35$ Msun, M2=17.73+/-0.30 Msun, R1=5.785+/-0.091 Rsun, and R2=5.816+/-0.063 Rsun. The disentangling thus resulted in the masses, which are somewhat higher than all previous determinations and virtually the same for both stars, while the light curve implies a slighly higher radius and luminosity for star 2. The above empirical values imply the logarithm of the internal structure constant log k2 = -1.937. A comparison with Claret's stellar interior models implies an age close to 2 millions yrs for both stars. The claimed accuracy of modern element determination of 1-2 per cent seems still a bit too optimistic and obtaining new high-dispersion and high-resolution spectra is desirable.Comment: 13 pages; accepted for publication in Astronomy and Astrophysic

Short period line profile and light variations in the Be star ω Orionis

We present the results of a multisite spectroscopic and photometric campaign on the Be star ω Orionis. From the photometry and radial velocity variation of several spectral lines, we confirm that the star is a variable with period . Only one period can be extracted from both the photometric and radial velocity observations. We find that the projected rotational velocity from the helium lines is considerably smaller than from the metal lines . The line profiles show an excess absorption feature moving from blue to red for half the period and from red to blue for the other half of the period. Another excess absorption feature moves exactly out of phase. The excess absorption features are present in photospheric lines as well as in lines which are significantly affected by circumstellar material, such as Hβ. From this we conclude that the periodic variations are most probably associated with corotating circumstellar materia

Increased number of intestinal villous M cells in levamisole -pretreated weaned pigs experimentally infected with F4ac+ enterotoxigenic Escherichia coli strain

Immunoprophylaxis of porcine postweaning colibacillosis (PWC) caused by enterotoxigenic Escherichia coli (ETEC) expressing F4 fimbriae is an unsolved problem. Just as ETEC strains can exploit intestinal microfold (M) cells as the entry portal for infection, their high transcytotic ability make them an attractive target for mucosally delivered vaccines, adjuvants and therapeutics. We have developed a model of parenteral/oral immunization of 4-weeks-old pigs with either levamisole or vaccine candidate F4ac+ non-ETEC strain to study their effects on de novo differentiation of antigen-sampling M cells. Identification, localization and morphometric quantification of cytokeratin 18 positive M cells in the ileal mucosa of 6-weeks-old pigs revealed that they were: 1) exclusively located within villous epithelial layer, 2) significantly numerous (P< 0.01) in levamisole pretreated/challenged pigs, and 3) only slightly, but not significantly numerous in vaccinated/challenged pigs compared with non-pretreated/challenged control pigs. The fact that levamisole may affect the M cells frequency by increasing their numbers, makes it an interesting adjuvant to study development of an effective M cell-targeted vaccine against porcine PWC

Effect of levamisole on the number of intestinal goblet cells in weaned pigs experimentally vaccinated against colibacillosis

VALPOTIĆ: Effect of levamisole on the number of intestinal goblet cells in weaned pigs experimentally vaccinated against colibacillosis. Vet. arhiv 79, 543-553, 2009. Postweaning colibacillosis (PWC) is an etiologically complex disease commonly induced by porcine F4ac + enterotoxigenic Escherichia coli (ETEC) for which no effective vaccine is available. The objective of this study was to determine the nonspecific immunomodulatory effect of levamisole in combination with specific intragastric immunization of weaned pigs with a candidate F4ac + non-ETEC oral vaccine on the population of intestinal goblet cells (GC). The pigs were immunized with F4ac + non-ETEC strain, in combination with or without levamisole. Seven days after immunization the pigs were challenged with F4ac + ETEC strain and 14 days following immunization they were euthanatized for sampling of specimens of the small intestine for immunohistochemistry and morphometric analyses. Samples of the ileum were tested for the presence of acidic and neutral carbohydrates, components of mucus produced and secreted by the intestinal goblet cells (GC). The volume density (V) of the PAS V + and AB +/PAS+ GC was determined using the stereological point-counting method. The Vv of the ileal PAS + GC was lowest (0.130 ± 0.075 mm3) in the pigs that were immunized wit

Utjecaj vodika u krutoj otopini čelika za opruge

This paper is concerned with the question of the brittle cracking of spring steel, which can occur already in the early stages of steel processing, i.e. during rolling, during the mechanical cutting of rolled profiles, or during any other type of mechanical manipulation where the harmful effect of remaining hydrogen has been observed. In order to investigate this question in greater depth, mechanical tests and fractographic analyses of the fracture surfaces were performed on cathodically hydrogenated test specimens of two types of spring steel, with and without alloyed nitrogen, in order to determine the critical concentration of hydrogen below which a relatively ductile fracture surface occurs, with good resistance to brittle cracking, and above which hydrogen embrittlement occurs.Ovaj rad odnosi se na problematiku krtog pucanja čelika za opruge već u njegovoj ranoj fazi prerade: pri valjanju, strojnom rezanju valjanih profila, ili kod neke druge mehaničke obrade, gdje je bio uočen škodljiv utjecaj zaostalog vodika. Pomoću uzoraka koji su bili katodno vodičeni, mehaničkog ispitivanja tih uzoraka i fraktografske analize prelomnih površina, bila je definirana kritična količina vodika. Ispod te kritične količine prisutna je još relativno žilava prelomna površina i dobra otpornost prema krhkom pucanju radi vodikove krhkosti. Iznad te vrijednosti, manifestira se vodikova krhkost

Spectrum of the secondary component and new orbital elements of the massive triple star Delta Ori A

$\delta$ Orionis is the closest massive multiple stellar system and one of the brightest members of the Orion OB association. The primary (Aa1) is a unique evolved O star. In this work, we applied a two-step disentangling method to a series of spectra in the blue region (430 to 450 nm), and we detected spectral lines of the secondary (Aa2). For the first time, we were able to constrain the orbit of the tertiary (Ab) - to 55 450 d or 152 yr - using variable $\gamma$ velocities and new speckle interferometric measurements, which have been published in the Washington Double Star Catalogue. In addition, the Gaia DR3 parallax of the faint component (Ca+Cb) constrains the distance of the system to (381 $\pm$ 8) pc, which is just in the centre of the Orion OB1b association, at (382 $\pm$ 1) pc. Consequently, we found that the component masses according to the three-body model are 17.8, 8.5, and 8.7 M$_{\odot}$, for Aa1, Aa2, and Ab, respectively, with the uncertainties of the order of $1$ M$_{\odot}$. We used new photometry from the BRITE satellites together with astrometry, radial velocities, eclipse timings, eclipse duration, spectral line profiles, and spectral energy distribution to refine radiative properties. The components, classified as O9.5 II + B2 V + B0 IV, have radii of 13.1, 4.1, and 12.0 R$_{\odot}$, which means that $\delta$ Ori A is a pre-mass-transfer object. The frequency of 0.478 cycles per day, known from the Fourier analysis of the residual light curve and X-ray observations, was identified as the rotation frequency of the tertiary. $\delta$ Ori could be related to other bright stars in Orion, in particular, $\zeta$ Ori, which has a similar architecture, or $\varepsilon$ Ori, which is a single supergiant, and possibly a post-mass-transfer object.Comment: 22 pages, 22 figure

Towards a consistent model of the hot quadruple system HD 93206 = QZ Carin\ae: II. N-body model

HD 93206 is early-type massive stellar system, composed of components resolved by direct imaging (Ab, Ad, B, C, D) as well as a compact sub-system (Aa1, Aa2, Ac1, Ac2). Its geometry was already determined on the basis of extensive photometric, spectroscopic and interferometric observations. However, the fundamental absolute parameters are still not known precisely enough. We use an advanced N-body model to account for all mutual gravitational perturbations among the four close components, and all observational data types, including: astrometry, radial velocities, eclipse timing variations, squared visibilities, closure phases, triple products, normalized spectra, and spectral-energy distribution (SED). The respective model has 38 free parameters, namely three sets of orbital elements, component masses, and their basic radiative properties ($T$, $\log g$, $v_{\rm rot}$). We revised the fundamental parameters of QZ Car as follows. For a model with the nominal extinction coefficient $R_V \equiv A_V/E(B-V) = 3.1$, the best-fit masses are $m_1 = 26.1\,M_{\rm S}$, $m_2 = 32.3\,M_{\rm S}$, $m_3 = 70.3\,M_{\rm S}$, $m_4 = 8.8\,M_{\rm S}$, with uncertainties of the order of $2\,M_{\rm S}$, and the system distance $d = (2800\pm 100)\,{\rm pc}$. In an alternative model, where we increased the weights of RV and TTV observations and relaxed the SED constraints, because extinction can be anomalous with $R_V \sim 3.4$, the distance is smaller, $d = (2450\pm 100)\,{\rm pc}$. This would correspond to that of Collinder 228 cluster. Independently, this is confirmed by dereddening of the SED, which is only then consistent with the early-type classification (O9.7Ib for Aa1, O8III for Ac1). Future modelling should also account for an accretion disk around Ac2 component.Comment: A&A, submitte

Evaluation of antioxidative effects of twelve 3-substituted-5,5-diphenylhydantoins on human colon cancer cell line HCT-116

Antioxidant effects of twelve 3-substituted-5,5-diphenylhydantoins in concentrations of 0.01, 0.1, 1, 10, and 100 μM on human colon cancer cell line HCT-116 were determined 24 h after treatment. The concentrations of superoxide anion radical (O2.-), nitrites (NO2-), and total glutathione were determined spectrophotometrically. Results indicated that treatment with all compounds induced a decrease in O2.- and an increase in NO2- concentrations in HCT-116 cells. Treatment with all compounds resulted in an increase in glutathione, and this indicates changes in redox homeostasis. Based on the obtained results, the investigated hydantoins act as antioxidants because they decrease the production of superoxide anion radical and increase concentrations of glutathione, but they also induce an increase in nitrite production. © TÜBİTAK