gases, such as NO and CO, play important roles both in normal physiology and in diseases. In recent years, interest has been directed towards other naturally-occurring gases, notably H2S, which is produced n body by three enzymes, namely cystathionine beta synthase (CBS), cystathionine gamma lyase (CSE) nd 3-Mercaptopyruvate sulfurtransferase (MST), present in mitochondria and/or cytosols where main ubstrate is L-cysteine. Recent studies have shown that vascular tissues generate measurable amount of 2S. NO is considered as inducer for H2S. H2S has gained importance as a neuromodulator and a asorelaxant factor and as the first endogenous gaseous ATP dependant K+ channel opener. It potenti-tes LTP by enhancing NMDA induced inward current.H2S induces vasorelaxation, inhibits insulin secre-ion and also has a role in inflammation. H2S also appear to have a role in neuroendocrine fuction be-ause it plays an important role in control of the hypothalamus-pitutary-adrenal axis, inhibit stimulated elease of corticotrophin-releasing hormone. H2S has been found to be decreased in patient with Alz-eimer’s disease and higher concentrations are found in patients with Down’s syndrome. It has a role in evelopment of hypertension, suggesting its role in CNS and CVS disorders. H2S it is well known toxic as with the smell of rotten eggs, is now proposed as a physiologically important molecule.

Hostile oil field corrosive environments have challenged the production and transportation operations of the petroleum industry. The estimated cost of corrosion on the U.S. economy in the year 2002 resulted in an expenditure of about 276 billion U.S. dollars. This amount was an increase of more than $100 billion over a previous five year period. Corrosion maintenance expenditures over this 5 year period were approximately 3.1% of the U.S. GDP, and stimulated congress to enact the Corrosion Prevention Act in 2007. One avenue available to successfully combat corrosion in the petroleum industry is the recent progress made in corrosion prediction applications for petroleum operations. Three such corrosion computer models have been developed at the University of Louisiana at Lafayette. These models are capable of predicting the physical conditions and corrosion rates inside pipelines and in producing oil and gas wells. The models are window based and described in this paper. An expert system module was developed, which adjusts the predicated corrosion rate based on various known reservoir and well subsurface parameters.

Nanostructured copper oxide (CuO) thin films were prepared by spray pyrolysis technique. X-ray diffraction was used to investigate the structural properties. Surface morphology was studied using scanning electron microscopy.Microstructure was studied using a transmission electron microscope, and energy-dispersive X-ray analysis was used to determine the elemental composition of prepared nanostructured CuO thin film. gas-sensing performance was conducted using static gas-sensing system, at different operating temperatures in the range of 200oC to 400oC for the gas concentration of 100 ppm. The maximum sensitivity (S=872) to H2S was found at the temperature of 250oC. Quick response (2 s) and fast recovery (5 s) are the main features of this film.

The removal of hydrogen sulfide (H2S) from airstreams was studied in a biotrickling filter packed with porous lava as a carrier of Thiobacillus thioparus (DSM5368) with counter current flows of the air and liquid streams. The effect of operating parameters on biotrickling filter performance was studied. Experiments were performed at different empty bed residence times (9-60 see), and moderate H2S concentrations (10-90 ppm) to assess the performance of biotrickling filter at different conditions of these parameters.The effect of superficial liquid velocity (0.98-1.95mh-1) on the performance of biotrickling filter was evaluated. Increasing superficial liquid velocity decreased removal efficiency of the BTF. The gradual change in the concentration of H2S in different heights of the BTF was investigated. Decreasing empty bed residence time lead to a slight increase in the homogeneity of the removal at different heights of the BTF; however the effect of change in the inlet concentration was insignificant.Complete removal was achieved in the first 85% of the bed. To gain a brief insight into the robustness of the biotrickling filter, its performance was investigated after several upsets in the system.

Wastewater treatment, oil and gas facilities along with the other industrial sections such as food, pulp and paper industries are the main sources of hydrogen sulfide emission to the atmosphere. Hydrogen sulfide is a toxic, flammable and corrosive gas, so several methods have been used for its removal. The physical and chemical methods are not cost effective and cause secondary pollution. The biological methods have recently received increasing interests as they can overcome the process and disposal costs. In this work a Biotrickling filter with counter-current flows of gas and liquid was modeled. In this dynamic model, it was assumed that hydrogen sulfide transferred from the gas phase to the liquid bulk, then to the biofilm. The effects of gas flow rate, liquid velocity, column height, and residence time on the performance of the bioreactor were investigated. The model showed that by increasing the gas flow rate up to 1.8 m3h-1, elimination capacity was increased, whereas removal efficiency was decreased. Moreover, by increasing the velocity of the trickling liquid from 2 to 15 m/s, removal efficiency increased from 26% to 99.7%. Higher heights of bioreactor resulted in higher removal efficiency of hydrogen sulfide and its effect was more significant at lower residence times.

Environment pollution and emission of toxic gases are one of the most important human challenges in the current century. Among polluted gases, land-fill gas with a high percent of methane could be considered as a plentiful source of energy. Biofiltration is a simple and economical method for removal of some contaminants such as hydrogen sulfide which is strongly toxic and corrosive. In this method, sweetening is done by passing the polluted gas through the bed of microorganism. For this purpose, a biofilter column of plexi glass with 15cm internal diameter and 2 m height was designed and constructed. The bed of this column was vermicompost mixed with the seashell. Then Thiobacillus thioparus bacteria which is cultured in the lab was previously, stabilized on the surface of the filling. The ability of this biofilter in 30 ppm concentration of H2S and different flow rate of landfill gas, in ambient temperature and atmospheric pressure, was studied. According to the experiments, it is observed that during 2 minutes, the yield is higher than 80%. In this condition, the concentration of H2S is desirable. Of course, in the study, the efficiency of biofilter in 30 ppm of H2S and flow rate of 2 L/min of polluted gas, was about 90 percent.

In the continuous gas lift operation, compressed gas is injected into the lower section of tubing through annulus. The produced liquid flow rate is a function of gas injection rate and injection depth. All the equations to determine depth of injection assumes constant density for gas based on an average temperature of surface and bottomhole that decreases the accuracy of gas lift design. Also gas-lift valve design requires exact temperature at each valve depth. Hence, enhanced gas lift design can be achieved by more accurate prediction of temperature profile in annulus and tubing. Existing temperature models for gas lifted wells have been roughly and inaccurately estimated for they ignore temperature variation due to phase changes as well as cooling the effect of injected gas inflow to the wellbore. Also, they find temperature profile from a known injection depth obtained from unreal previous assumptions.In this paper a novel model is developed to obtain the temperature profile in annulus and tubing of gas lifted well and injection depth simultaneously. This new model considers all the real conditions such as heat transfer between triple systems of liquid slug, injected gas and formation, cooling effect of gas inflow, joule-Thomson effect, potential energy, and phase changes in both conduits.The model was applied on Iran's Aghajary oil field wells. Results showed how ignoring temperature variations caused substantial errors in gas lift design. From our experience and according to results of this simulator, it can be concluded that the calculated injection depth from classic method and developed model had a difference between 200 and 400m for Aghajary field wells, as the total depth varied from 3000 to 4200m. The comparison made between temperature profile resulted from developed simulator and previous temperature models using temperature survey data of Aghajary wells showed much better matching for developed simulator.