2,016 research outputs found

    A New Concept of Transonic Galactic Outflows in a Cold Dark Matter Halo with a Central Super-Massive Black Hole

    Full text link
    We study fundamental properties of isothermal, steady and spherically symmetric galactic outflow in the gravitational potential of a cold dark matter halo and a central super-massive black hole. We find that there are two transonic solutions having different properties: each solution is mainly produced by the dark matter halo and the super-massive black hole, respectively. Furthermore, we apply our model to the Sombrero galaxy. In this galaxy, Chandra X-ray observatory detected the diffuse hot gas as the trace of galactic outflows while the star-formation rate is low and the observed gas density distribution presumably indicates the hydrostatic equilibrium. To solve this discrepancy, we propose a solution that this galaxy has a transonic outflow, however, the transonic point forms in a very distant region from the galactic center (?∼\sim 127 kpc). In this slowly accelerated transonic outflow, the outflow velocity is less than the sound velocity for most of the galactic halo. Since the gas density distribution in this subsonic region is similar to the hydrostatic one, it is difficult to distinguish the wide subsonic region from hydrostatic state. Such galactic outflows are dfferent from the conventional supersonic outflows observed in star-forming galaxies.Comment: 7 pages, 3 figures, accepted for publication in JPS Conference Proceedings. arXiv admin note: substantial text overlap with arXiv:1405.345

    Cerebral amoebiasis

    Get PDF

    Design and implementation of an oil leakage monitoring system based on wireless network

    Get PDF
    Monitoring pipeline leaks is one of the recent hot studies. Leakage may occur because of time corrosion in the tube raw materials. To reduce the negative consequences of this leak, an effective leak detection system is used to prevent serious leakage accidents and damage in oil pipelines. Buildings, ecosystems, air pollution, and human life are all at risk in case of leakage occurs which could lead to fires. This paper introduces one of the research methods for the detection of pipeline leaks with a particular focus on software-based methods. The computer board interface (CBI) and wireless sensor networks have been used beside Arduino as a micro-monitor for the entire system. ZigBee is also utilized to send read data from sensors to the monitoring system displayed on the LabVIEW graphical user interface (GUI). The operator can take direct action when a leak occurs. The effectiveness of the leakage monitoring process and its practical use are demonstrated by the introduction of computerized techniques based on pressure gauge analysis on a specific pipeline in the laboratory. The result showed that the system is widely covered, accurate data transmission and robust real-time performance which reduces economic losses and environmental pollution

    Corrosion, Passivity and Pitting of Inconel (600) in Sulphuric Acid

    Get PDF
    A potentiostatic study of the behaviour of Inconel (600) in molar sulphuric acid has been carried out over the temperature range 293-313 K. Values have been established for the potentials and current densities of the corrosion, active-passive transition, passivity and transpassive states. For corrosion, the current density (ic) and potential (Ec) have been determined from well-defined Tafel lines. The potential and current density prior to the commencement of passivity have been obtained corresponding respectively to the critical potential (Ecr( and to the current density (icr) for the active-passive transition state. The passive range was defined by the respective potentials and current densities for passive film formation and dissolution. The dissolution point was correlated with transpassive potential (Et) and current density (it). All the estimated potentials and current densities for the various states were influenced by temperature and the presence of additives in the sulphuric acid. Additives such as nitric acid, thiourea and sodium chloride lowered the corrosion current density (ic) of the alloy while hydrochloric acid enhanced the value of ic. Addition of thiourea or sodium chloride or hydrochloric acid caused a shift in the corrosion potential (Ec) to less negative values while nitric acid shifted Ec to more negative potentials. The kinetic effect of the additives have been studies. Values of activation energy (E) were considered to be apparent and some negative values of E have been obtained with certain additives for the critical and passivity processes. Such negative E values were attributed to small values of true energies of activation together with relatively large exothermic enthalpies of such processes

    COMPARATIVE PHARMACOGNOSTICAL STUDY OF THE GENUINE AND MARKET SAMPLES OF THE STEM BARK OF CIRABILWA (HOLPTELEA INTEGRIFOLIA PLANCH.)

    Get PDF
    Context: The stem bark of Cirabilwa (Holoptelea integrifolia Planch.) is used for treating various disease conditions including Dyspepsia, Flatulence, Colic, Helminthiasis, Vomiting, Skin diseases, Diabetes Mellitus, Haemorrhoids and Rheumatism in traditional system of medicine since ancient times. As a part of a proposed clinical study, sufficient quantity of the plant drug was required to evaluate the antidyslipidemic effects, which was procured from market. Aim: This study was designed to identify and compare the pharmacognostical features of the genuine hand collected samples and market samples of the stem bark of this medicinal plant, so as to prove the genuinity of the market samples before using it for clinical study. Materials and Methods: Macroscopic and microscopic methods were applied to determine the diagnostic features of the shade dried samples of the intact stem bark of both samples of the drug and was compared with the available data. Results: The shape, color, thickness, odour, consistency, fracture and surface characteristics were determined. Compound microscope images showed the presence of ray cells, stone cells, starch grains, rhomboidal crystals in both the samples. Conclusion: The study confirmed the identity of both genuine and market samples. Comparable results were obtained which proved the genuinity of the market samples of the stem bark of Cirabilwa (Holoptelea integrifolia Planch)

    Thermodynamic and Kinetic Study of the Adsorption of Pb (II) from Aqueous Solution Using Bentonite and Activated Carbon

    Get PDF
    The adsorption of Pb(II) ions onto bentonite and activated carbon was investigated. The effects of pH, initial adsorbent dosage, contact time and temperature were studied in batch experiments. The maximum adsorption capacities for bentonite and activated carbon were 0.0364 and 0.015 mg/mg, respectively. Thermodynamic parameters such as Gibbs free energy change, Enthalpy change and Entropy change have been calculated. These thermodynamic parameters indicated that the adsorption process was thermodynamically spontaneous under natural conditions and the adsorption was endothermic in nature. Experimental data were also tested in terms of adsorption kinetics, the results showed that the adsorption processes followed well pseudo second- order kinetics
    • …
    corecore