Recently, claims have been made of the detection of 'warm-hot' gas in the intergalactic medium. Kaastra et al. (2003) claimed detection of ~ 106K material in the Coma Cluster but studies by Arnaud et al. (2001), and our analysis of the Chandra observations of Coma (Vikhlinin et al. 2001), find no evidence for a 106 K gas in the cluster. Finoguenov et al. (2003) claimed the detection of 3 X 106 gas slightly off-center from the Coma Cluster. However, our analysis of ROSAT data from this region shows no excess in this region. We propose an alternative explanation which resolves all these conflicting reports. A number of studies (e.g. Robertson et al., 2001) have shown that the local interstellar medium undergoes charge exchange with the solar wind. The resulting recombination spectrum shows lines of O VII and O VIII (Wargelin et al. 2004). Robertson & Cravens (2003) have .shown that as much as 25% of the Galactic polar flux is heliospheric recombination radiation and that this component is highly variable. Sporadic heliospheric emission could account for all the claims of detections of 'warm-hot' gas and explain the conflicts cited above.

We review recent systematic investigation of the X-ray spectra of early type galaxies by using the Einstein data base and present new results by the ROSAT observations. The Einstein data suggested that the galaxies with low X-ray to optical luminosity ratio may have another very soft component. ROSAT observations confirm its presence and call for further study to understand the nature of this very soft emission. The X-ray bright galaxies have emission temperature of ∼0.8keV ∼0.8keV and show radial gradients in the sense that X-ray emission is softer and more absorbed in the inner region.

Waste gasification can generate hydrocarbon gases that may be utilized for the synthesis of chemicals or liquid fuels, or for fuel cell power generation, if extensive, deep syngas cleaning is initially conducted. Conventional gas cleaning technology for such applications is expensive and may limit the feasibility of wet technology. Conventional cold gas cleanup (scrubbing by solvents) technique needs the temperature of raw waste gasification gas ranging from 900 to 1600℃ reduced to room temperature. Then, the cleaned - up syngas needs to be reheated. Obviously, the process is energetically inefficient. It is the objective of this study to economically meet the most stringent cleanup requirements without reheating syngas for these applications. We investigated the temperature and pressure effect in breakthrough performance of various sorbents for desulfurization and de-chlorination. Based on the results obtained during the desulfurization (Fe₂O₃, Fe₃O₄, ZnO) and the dechlorination (Na₂CO₃, NaHCO₃, Na₂O) screening tests, ZnO and Na₂O were selected as preferred optimum sorbents. H₂S breakthrough time corresponds to an effective capacity of approximately 11 g Cl/100 g of material. Also, HCl, breakthrough time corresponds to an effective capacity of approximately 5 g Cl/100 g of material. ZnO and Na₂O at high temperature of around 550℃ display high sorption performance and removal efficiency for waste syngas along with H₂S and HCl. Although there is an issue of CO₂ recovery in warm gas clean-up technology for desulfurization, we have obtained an interesting new alternative warm gas clean-up system with heat budget merit.

This work presents an experimental study of the influence of lifting velocity on cake formation during filtration. For design of hot gas cleanup system using ceramic filter reactor, the most important consideration is coating conditions of sorbent in filter surface (for example : lifting velocity, coating weight of sorbent, pulsing interval and removal effect for dechlorination and desulfurization). We studied the optimum operation condition as paticle size and lifting velocity using a ceramic filter reactor at 550oC. Based on the results obtained during cold and hot test, optimum lifting velocity in a ceramic filter reactor was selected 0.68 m/s. Also, the removal behaviour of the ceramic filter during filtration was studied using differential pressure. Optimum removal efficiency for dechlorination and desulfurization accomplished at differential pressure condition over 74 mmH2O.