421 research outputs found

    HD 152246 - a new high-mass triple system and its basic properties

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    Analyses of multi-epoch, high-resolution (R ~ 50.000) optical spectra of the O-type star HD 152246 (O9 IV according to the most recent classification), complemented by a limited number of earlier published radial velocities, led to the finding that the object is a hierarchical triple system, where a close inner pair (Ba-Bb) with a slightly eccentric orbit (e = 0.11) and a period of 6.0049 days revolves in a 470-day highly eccentric orbit (e = 0.865) with another massive and brighter component A. The mass ratio of the inner system must be low since we were unable to find any traces of the secondary spectrum. The mass ratio A/(Ba+Bb) is 0.89. The outer system has recently been resolved using long-baseline interferometry on three occasions. The interferometry confirms the spectroscopic results and specifies elements of the system. Our orbital solutions, including the combined radial-velocity and interferometric solution indicate an orbital inclination of the outer orbit of 112{\deg} and stellar masses of 20.4 and 22.8 solar masses. We also disentangled the spectra of components A and Ba and compare them to synthetic spectra from two independent programmes, TLUSTY and FASTWIND. In either case, the fit was not satisfactory and we postpone a better determination of the system properties for a future study, after obtaining observations during the periastron passage of the outer orbit (the nearest chance being March 2015). For the moment, we can only conclude that component A is an O9 IV star with v*sin(i) = 210 +\- 10 km/s and effective temperature of 33000 +\- 500 K, while component Ba is an O9 V object with v*sin(i) = 65 +/- 3 km/s and T_eff = 33600 +\- 600 K.Comment: 9 pages, 6 figures, accepted for publication in Astronomy and Astrophysic

    Adsorption and magnetic separation of lead from synthetic wastewater using carbon/iron oxide nanoparticles composite

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    Background and purpose: Removal of lead as a toxic metal from contaminated water resources is necessary due to the dangerous effect of lead. One of the most effective methods of removal is the adsorption process. The aim of this study was adsorption and magnetic separation of lead from synthetic wastewater using iron oxide nanoparticles and carbon (ION/C) composite Material and Methods: In this study nanoparticles of iron oxide (ION) were used as a source of iron for magnetic separation of powder activated carbon from solution samples. The physical and surface properties of the adsorbent were studied along with influencing factors (pH, contact time, adsorbent dosage, initial lead concentration, and temperature) on the adsorption process. Kinetic equations and equilibrium isotherms studies were also conducted. Results: The size of ION and specific surface area of ION/C were found to be 30-80 nm and 671.2 m2/g, respectively. We observed that the adsorption process reached equilibrium at 60 min and pH=6and adsorption efficiency increased by increasing the amount of adsorbent and temperature. Maximum adsorption capacity based on Langmuir isotherms was obtained 67.1mg/g at 50 °C. Conclusion: According to this study it is believed that magnetized active carbon by keeping its physical and surface properties could be a suitable method to solve some related problems including separation and filtration

    Study of the pitch change of carbon coils during their growth

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    AbstractIn the present paper, carbon coils (CCs) were prepared by CVD. Their morphology, particularly pitch changes of the carbon coils prepared in different conditions were observed. It was found that the carbon source flow plays an important role in carbon coil growth and its morphology evolution. The appropriate atmosphere and flow rate is beneficial to the steady reactivity of catalyst particles. As such each carbon coil can grow well and have an exact growth rate. When the carbon supply is sufficient, the CCs exhibit close spiral and small coil diameter. When carbon supply decreases, small carbon supply leads to large pitch and coil diameter. CCs can be synthesized with different coil pitch under different carbon supply. This may be of great significance for the controllable preparation of carbon coil and its application

    The prevalence of Human Papilloma Virus (HPV) infection in the oligospermic and azoospermic men

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    Background: Human papilloma virus (HPV) infection is one of the most common sexually transmitted diseases that affects men like women and infected cutaneous and mucosal squamous epithelium. The aim of the present study was to determine the prevalence of HPV in the semen of oligospermic, azoospermic and normal patients. Methods: From June 2012 to June 2013, a total of 90 individuals were enrolled in this cross sectional comparative study. The participants were classified into three groups (oligospermia, azoosprmia and normal). This classification was based on a new WHO reference values for human semen characteristics published on 2010. After extraction of DNA from specimens L1 gene of HPV was amplified by nested polymerase chain reaction (Nested-PCR) and the PCR products of positive specimens were genotyped using INNO-LiPA HPV Genotyping Extra assay. Results: Among 50 confirmed oligospermic male, 15 were HPV DNA positive (30). In azoospemic group we had 8 HPV DNA positive (40) and in normal group just 3 of 20(15) samples were positive. Statistical assessment was done with SPSS v.15. Chi-square test showed no significant relationship between 3 groups results. Based on independent samples t-test, we found statistical significant relationship for sperm count (p<0.05) and sperm motility (slow) (p<0.05) in oligospermic group positive samples compared with negative. In the present study, 13 HPV genotypes were detected among positive samples. HPV genotypes 16, 45 in the high risk group and 6,11,42 in the low risk group were more frequent than the others. Conclusion: The current study shows that HPV infection can affect on sperm count and motility and decrease count of sperm cell and decrease motility capability of these cells

    Rheology of Active-Particle Suspensions

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    We study the interplay of activity, order and flow through a set of coarse-grained equations governing the hydrodynamic velocity, concentration and stress fields in a suspension of active, energy-dissipating particles. We make several predictions for the rheology of such systems, which can be tested on bacterial suspensions, cell extracts with motors and filaments, or artificial machines in a fluid. The phenomena of cytoplasmic streaming, elastotaxis and active mechanosensing find natural explanations within our model.Comment: 3 eps figures, submitted to Phys Rev Let