Impact of sulphur contamination on the performance of mixed ionic-electronic conducting membranes for oxygen separation and hydrogen production

PhD ThesisMixed ionic-electronic conducting (MIEC) membranes are a promising technology for oxygen separation but they are not commercialised yet due to sealing issue and sensitivity to impurities in feedstock. In this study, La0.6Sr0.4Co0.2Fe0.8O3- (LSCF6428) was successfully sealed for long-term operation of 963 h using a gold-glass-ceramic sealant. The membrane was then tested for air separation in presence of hydrogen sulphide for 100 h and results showed that the impurity caused a drop in oxygen flux to zero within few hours. The flux could not be fully restored after hydrogen sulphide removal and only 6 to 35% was recovered. It was proposed that hydrogen sulphide was adsorbed on the membrane in the form of sulphur and it occupied oxygen vacancies. With time, strontium segregates toward sulphur to form irreversible layer of strontium sulphate. To restore the damaged surface, the membrane was treated by 1% (mol) of hydrogen for 20 h and the recovery improved from 6 to 12%. It was discovered that the poisoning mechanism is a function of oxygen partial pressure and change of partial pressure from 0.21 to 0.01 bar resulted in 90% recovery and this can be used as a strategy to reduce the damage. The next step was to test the membrane for hydrogen production using 1% (mol) of methane and results showed that methane conversion was steady at 33% for 350 h. Methane oxidation was also carried in presence of hydrogen sulphide but it resulted in drop of conversion to 8%. However, the conversion was slowly regenerating with time and it reached a constant value of 15%. This recovery was interpreted by the reaction of methane with hydrogen sulphide or methane decomposition and the membrane acted as a catalyst for these reactions. After hydrogen sulphide removal from the feed, the conversion kept on decreasing and this was linked to the change of membrane properties and therefore the membrane could not provide the sites for methane-oxygen reaction. For better stability under hydrogen sulphide, the membrane was modified by adding a powder of LSCF6428 material over the dense membrane. This dual layer membrane was stable for air separation under hydrogen for 33 h and the flux was only reduced by 5%

Working memory learning method and astrocytes number in different subfields of rat's Hippocampus

The aim of this study was evaluation of the astrocytes number in different subfields of rat's Hippocampus after spatial learning with usage of Morris Water Maze technique and working memory method. In this study, between 2005-2006 years in Pasteur institute of Iran-Tehran and histological department of Gorgan University with usage of Morris Water Maze and working memory technique, we used 14 male albino wistar rats. Seventh rats were in control group and 7 rats in working memory group. After histological preparation, the slides were stained with PTAH staining for showing the Astrocytes. Present results showed significant difference in astrocytes number in CA1, CA2 and CA3 areas of hippocampus between control and reference memory group. The number of astrocytes is increased in working memory group. Then we divided the hippocampus to three parts: Anterior, middle and posterior and with compare of different area (CA1, CA2 and CA3) of hippocampus, we found that the differences between Anterior-middle and Middle-Posterior of CA1 and CA2 area of hippocampus were significant, whereas the difference between Anterior-Posterior parts was not significant in CA1 and CA2 areas. In CA3 area, the difference between Anterior-Middle and Anterior-Posterior parts was significant, whereas the difference between middle and posterior parts was not significant. We concluded that the number of astrocytes increased due to spatial learning and working memory technique. © 2008 Science Publications

Feasibility of electron cyclotron autoresonance acceleration by a short terahertz pulse

A vacuum autoresonance accelerator scheme for electrons, which employs terahertz radiation and currently available magnetic fields, is suggested. Based on numerical simulations, parameter values, which could make the scheme experimentally feasible, are identified and discussed

ASSESSMENT AND ASSURANCE OF SERVICE QUALITY IN PEDIATRIC HEALTHCARE IN QATAR

The purpose of this study was quality assessment and quality assurance in pediatric services of public and private hospitals in Qatar. The purpose of quality assessment was to identify gaps in the delivered services; while quality assurance process was carried out to ensure no future gaps in quality occur. The objectives were achieved using a modified SERVQUAL scale and Fuzzy-Quality Function Deployment (Fuzzy- QFD) approach. Data from 179 participants who visit public/private hospitals in Qatar was analyzed to find the gaps between expectations and perceptions. The results of the SERVQUAL study indicates negative quality gaps for all the service quality dimensions. The inference that can be drawn from this result is that, in general, the people are dissatisfied by the pediatric healthcare services offered by the public/ private hospitals in Qatar. Thus, the managers in these hospitals should work towards improving the quality of their services, in particular, the responsiveness and empathy dimensions. The output of the SERVQUAL study was then utilized to model those variables that are important in assuring service quality. This was achieved using Fuzzy-QFD model which demonstrates that there is a set of variables that should be accorded prime importance by the hospitals administrators’ to assure quality in pediatric services

Capability of Plant Growth-Promoting Rhizobacteria (PGPR) for producing indole acetic acid (IAA) under extreme conditions

Plant Growth-Promoting Rhizobacteria (PGPR) inhabiting the area around the plant roots or in plant tissues and stimulate plant growth directly or indirectly. Synthesis of the phytohormone auxin indole-3-acetic acid (IAA) is one of the direct effects of PGPR on plant growth. This study aimed to isolate and screen IAA producing bacteria from soil and study the impacts of the alkalinity and salinity on IAA production and total antioxidant activity of the highly IAA producing strain. From the fifteen isolates tested, six were selected as efficient IAA producer, from which one isolate was highly IAA producer. The highly producing isolate was identified based on molecular characteristics using 16S rRNA. The sequence analysis showed 99% similarity with Bacillus subtilis from GenBank data base. The strain yielded IAA in a wide range of pH (5-9), giving its maximum IAA production at pH 8. High IAA concentration was also observed in the presence of 0.5% and 1% NaCl in comparison with control (with no NaCl). Furthermore, the results indicated that, total antioxidant was increased in acidic (pH 5 and pH 6) and alkaline (pH 8) media, as well as in salinity up to 2%. This study could be stated as the prospective of IAA producing bacterial isolate in the field, as a result, using it as alternative valuable biofertilizer. DOI: http://dx.doi.org/10.5281/zenodo.141279