The effect of nanoparticles on oil sludge biodegradation by Chromohalobacter sp. isolated from the Bahregan area in the Persian Gulf

In this study, sampling was performed from oil-sludge-contaminated site from Bahregan area in the Persian Gulf of Iran. Alkane-degrading bacteria from oil sludge were isolated by chemotaxis in hydroxylase gene. Thus, Chromohalobacter strain was selected as useful strain for the biodegradation of oil sludge. The biodegradation of oil sludge by Chromohalobacter in the absence and presence of nanoparticles in light and dark conditions was investigated by gas chromatography–mass spectrometry analysis. Results of analysis showed that although Chromohalobacter is capable of the biodegradation of oil sludge, Fe₂O₃ and Fe₃O₄ nanoparticles with this bacterium increase the biodegradation in a short time.     

Instability of petroleum oil degradation by induction of mutation in 45 kb and 60 kb plasmids

A strain of Pseudomonas sp. was isolated from oil‐contaminated soil on petroleum oil agar. This isolate used different alkenes and had two plasmids on gel agarose. These plasmids are probably involved in oil degradation. The mutant strain, which were obtained by sub‐culturing in nutrient broth (oil^?), lost one plasmid (60?Kb) and had deletion in another plasmid (45?Kb). This result suggests that the ability to degrade petroleum oil must depend on these plasmids. The wild isolate has maximum OD of 2.5 for growth on petroleum oil, however the mutant did not have any significant growth on petroleum. GC Profiles of petroleum oil after degradation by wild and mutant were investigated.     

Isolation of a flocculating Saccharomyces cerevisiae and investigation of its performance in the fermentation of beet molasses to ethanol

The present study aims at evaluating the performance of the relative importance of different types of interactions in yeast cell flocculation. The yeasts isolated from several sources, purified and identified by morphological and biochemical methods. About 50 strains of yeast were isolated on PDA medium, among those strains six strains were flocculent and one of them was identified as Saccharomyces cerevisiae. The influence of different additives on the flocculation was investigated and it was shown that pistacia gum (turpentine) increases the flocculation up to 93.8%. Addition of ammonium sulfate (0.2 g l⁻¹) increases the production of alcohol to 6.19%.     

Manufacturing and structural analysis of antimicrobial kefiran/polyethylene oxide nanofibers for food packaging

Kefiran, a branched glucogalactan, is a useful microbial polysaccharide produced by lactic acid bacteria. The aim of this study was to evaluate the antimicrobial activity of kefiran nanofibers as a biocontrol agent for food packaging as well as food preservation. Thus, kefiran/polyethylene oxide (PEO) nanofibers were fabricated using the electrospinning method. Kefiran was produced from raw milk with 0.5% fat and 10 g of kefir grain and was separated from it by ethanol. Structural analysis of kefiran was detected by means of nuclear magnetic resonance and Fourier transforms infrared spectroscopy (FTIR). Antimicrobial properties of kefiran were assayed against Rhizoctonia, Pseudomonas sp. (isolated from soil at Isfahan University) and Staphylococcus aureus (S. aureus). Electrospun kefiran/PEO nanofibers were characterized by scanning electron microscopy, optical microscopy and ATR-FTIR techniques. Hydrophilicity and in vitro biodegradation of the kefiran/PEO nanofibers were investigated, as well. The results showed that the mean diameter of the nanofibers was 607.5 nm. The contact angle measurement result was 51.5° ± 0.71 with normal hydrophilicity. First of all, antimicrobial properties of kefiran were confirmed against different types of microorganisms. Moreover, the result obtained in this study showed that kefiran/PEO nanofibers with oxidizing functional groups on them have antimicrobial activity against S. aureus. Biodegradation of kefiran/PEO nanofibers was also confirmed by FTIR.     

Tensile fatigue behavior of polyamide 66 nanofiber yarns

Nanofiber yarns with twisted and continuous structures have potential applications in fabrication of complicated structures such as surgical suture yarns, artificial blood vessels, and tissue scaffolds. The objective of this article is to characterize the tensile fatigue behavior of continuous Polyamide 66 (PA66) nanofiber yarns produced by electrospinning with three different twist levels. Morphology and tensile properties of yarns were obtained under static tensile loading and after fatigue loading. Results showed that tensile properties and yarn diameter were dependent on the twist level. Yarns had nonlinear time‐independent stress–strain behavior under the monotonic loading rates between 10 and 50 mm/min. Applying cyclic loading also positively affected the tensile properties of nanofiber yarns and changed their stress–strain behavior. Fatigue loading increased the crystallinity and alignment of nanofibers within the yarn structure, which could be interpreted as improved tensile strength and elastic modulus. POLYM. ENG. SCI., 55:1805–1811, 2015. © 2014 Society of Plastics Engineers     

Technical–economical analysis of the Saveh biogas power plant

The resource limitation of fossil fuels and the problems arising from their combustion has led to widespread research on the accessibility of new and renewable energy resources. Solar, wind, thermal and hydro sources, and finally biogas are among these renewable energy resources. But what makes biogas distinct from other renewable energies is its importance in controlling and collecting organic waste material and at the same time producing fertilizer and water for use in agricultural irrigation. Unlike other forms of renewable energy, biogas neither has any geographical limitations and required technology for producing energy and nor is it complex or monopolistic. Considering the ever increasing amount of different types of organic waste materials (about 15 million tonnes) in Iran, working on the control of waste material and biogas production becomes inevitable.In this paper, biogas and the benefits from its production are discussed, as is the technical-economic analysis of the Saveh biogas power plant as a case study.     

Effects of membrane electrode assembly fabrication parameters on the proton exchange membrane fuel cell performance

In this paper, experimental investigation focuses on analysing the simultaneous influences of four different fabrication parameters, including carbon loading in GDL, Nafion content in CL, drying temperature of CL and hot pressing temperature. Active area of the MEAs was 25?cm² and characterisation of them was carried out by a 700?W fuel cell test station. Results show that the existence of MPL in GDL can improve performance of the PEMFC because of creating an even and steady surface which decreases ohmic resistance. The results confirm that the robustness of the optimum fabrication parameters influence performance of the cell. Optimum values of the parameters are: carbon loading in GDL, 3?mg?cm^?2; catalyst drying temperature, 60°C and Nafion content, 45%; but hot pressing temperature effect was lower than the other parameters. The expected performance of the fuel cell at optimum condition is 184.447?mW?cm^?2.