proton exchange membrane fuel cells (pemfcs) with a dead-ended anode and cathode can obtain high hydrogen and oxygen utilization by a comparatively simple system. nevertheless, the accumulation of the water in the anode and cathode channels might cause a local fuel starvation degrading the performance and durability of pemfcs. in this study, a brand new design for a polymer electrolyte membrane...

background: hydrogen sulfide (h 2 s) exhibits both physiological and toxicological roles in the biological systems. acute exposure to high levels of h 2 s is life threatening while long-term exposure to ambient levels of h 2 s elicits human health effects. objective: to study the harmful effects of long-term exposure to low levels of h 2 s on human blood cells. methods: 110 adult workers from i...

the role of nickel as catalyst on the conversion of methane and ethylene in a gas phase flow reactor in the absence of oxygen is studied. in this study, nickel in its different forms is used as catalyst. the role of pressure, flow rate, and temperature on the conversion of feed gases is investigated. the experiments have been carried out in the presence and absence of the catalysts to measure t...

background: high amount of heavy metals in sludge is one of the major obstacles to its use on farms. the present study aimed to investigate the possibility of leaching heavy metals from wastewater sludge by fenton method and determine the optimum level of parameters, such as iron, hydrogen peroxide, time, and ph for fenton reaction.   methods: the effects of various parameters, such as ph (2-9)...

background: hydrogen sulfide (h2s) suicides have been frequent in japan in recent years. this study was performed to describe the epidemiologic profile of an outbreak of h2s suicides in japan. methods: in september 2008, questionnaires about patients involved in h2s suicides were sent to 250 hospitals in japan. data collected from each patient included gender, age, clinical manifestations, date...

this paper describes the application of process integration principles to the design of oil refineries hydrogen network. in this regard, a design hierarchy as well as heuristics and required guidelines are proposed. the recommended rules compensate lack of procedure to the design and make the design process easier. the guiding principles of the design are based upon pinch technology and extendi...

we present detailed theoretical studies of the h-bonded complexes formed from interaction between 5-fluorouracil and various six-membered cyclic nitrosamine compounds. in this study, an investigation on intermolecular interactions in x-nu (x = ch2, sih2,bh, alh, nh, ph, o and s) complexes is carried out using density functional theory. the calculations are conducted on b3lyp/6-311++‏‏g** level ...

joule-thomson cooling systems are used in refrigeration processes such as cryogenic gas liquefaction. although extensive studies have been carried out by researchers, most of them include cryogenic heat exchangers and their associated fields. in the current study, an attempt was made to indicate the effect of using inappropriate operational conditions in a cryogenic joule-thomson cooling system...

â a model is developed for separation of multicomponent gas mixtures in a countercurrent hollow fiber membrane module. while the model’s solution in countercurrent module usually involves in a time consuming iterative procedure, a proper initial guess is proposed for beginning the calculation and a simple procedure is introduced for correcting the guesses, hereby the cpu time is decreased ess...

enaminones are those structures made up three various functional groups including carbonyl, alkeneand amine groups which arelocated along with each other in a conjugate fashion. these compoundsare of much attention due to special characteristics and numerous applications. in the paper, sixvarious enaminone structures were theoretically optimized and after concluding, were compared withequivalen...