20,773 research outputs found

    Effect of geometrical size of the particles in a hot and dense hadron gas

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    Incorporation of the finite size of baryons into the equation of state (EOS) of a hot and dense hadron gas (HG) in a thermodynamically consistent manner has been a much studied problem. We first review its current status. Various models have been proposed in order to account for the repulsive force generated by the hard-core geometrical size of the baryons resulting in an excluded volume effect in the EOS. We examine the criterion of the thermodynamical consistency of these models and summarize their shortcomings. In order to remove the shortcomings, we propose a new model which incorporates the excluded volume effect in a thermodynamically consistent manner. We find that the new model works even for the cases of extremely large temperatures and densities where most of other approaches fail. Furthermore, the new expressions for thermodynamical variables resemble in form with those obtained from thermodynamically inconsistent models and thus a useful correction factor has been suggested here which converts inconsistent expressions into thermodynamically consistent ones. Finally we compare the predictions of new model with those obtained from various old models.Comment: 19 pages, 9 figures, accepted for publication in Phys. Rev.

    Fly ash as a coating material for plasma spray coatings

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    The present piece of work has been undertaken to use fly-ash in developing plasma spray coatings on metal substrates. Fly-ash and fly-ash with 5% alumminum metal powder were (premixed thoroughly) plasma sprayed on stainless steel and aluminum substrates at various operating power levels of plasma torch. The coating thus produced, was characterized by thickness measurement, X-ray diffraction analysis, microscopic studies and measurement of coating-substrate adherence strength. X-ray analysis reveals the presence of alumina, silica and mullite phases. The adherence strength seems to increase with aluminum addition to flyash

    Premature harvesting of wild Musli (Chlorophytum borivilianum, Baker) and its impact on raw material quality: A case of Katni forest division, Madhya Pradesh

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    Katni is a major raw medicinal plant market of Central India. An attempt has been made to find out prevalent harvesting method of Musli (Chlorophytum borivilianum) and visual inspection of raw (dry) market samples collected from Katni market. Musli tubers were found adulterated both intentionally and unintentionally by various stakeholders in the market. The stakeholders adopted malpractices like selling similar looking C. tuberosum, C. arundinaceum species of musli along with genuine (C. borivilianum) material and occasionally dried roots of different species. Major reasons for poor quality in the study area are premature root harvesting, mis-identification of species, mixing of similar looking species etc. The study recommends that harvesting should be done after maturation (November) and awareness about species identification, processing among various stakeholders is required