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کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Iranian Journal of Chemistry and Chemical Engineering
- نوع مقاله: Journal Article
- کلمات کلیدی: Simulation,Production,Bioreactor,Poly(3-hydroxybutyrate)
- چکیده:
- چکیده انگلیسی: Recently, many economic studies of poly(3-hydroxybutyrate) PHB production on an industrial scale, and the impact of replacing petrochemical polymers by PHB were carried out, clearly indicating that the most crucial factors to reduce the cost of producing biopolymers are allotted to the application of microbial production strains capable of high productivity in inexpensive carbon sources, high cell density cultivation methods, cheap yet effective methods for the extraction of PHB and other polyhydroxyalkanoates (PHAs), and gene transfer from bacteria to plants. We present current strategies to reduce the production price of biological PHA. Because an important part of the PHA production cost is related to the cost of carbon source, the article focuses on the use of natural gas as an inexpensive and readily available C1-carbon source. Since the first and foremost point in PHA production is biomass growth, we discuss different types of bioreactors to be potentially used for efficient biomass production from natural gas, which facilitates the subsequent selection of the ideal bioreactor for PHA production from this substrate. Nowadays, process simulation software can be used as a powerful tool for analysis, optimization, design, and scale up of bioprocesses. Controlling the process design by in silico simulations instead of performing an excessive number of lab-scale experiments to optimize various factors to save in time, material and equipment. Simulation of PHA production processes to find the optimal conditions can play a decisive role in increasing the production efficiency. Computational fluid dynamics and mathematical modeling helps us to achieve a better understanding of the role of different nutrients, flow parameters of gaseous substrates, efficient feeding strategies, etc. This finding leads to higher productivity by prediction of parameters e.g. nutrient supply and biomass concentration time profile and their respective yields.
- انتشار مقاله: 14-11-1396
- نویسندگان: Kianoosh Khosravi Darani,Fatemeh Yazdian,Hamid Rashedi,Neda Madadian Bozorg,Mohsen Moradi,Soheil Rezazadeh Mofradnia,Martin Koller
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Chemistry and Chemical Engineering
- نوع مقاله: Journal Article
- کلمات کلیدی: Pseudomonas aeruginosa,optimization,Biosurfactants,Molasses,Surface tension,Glycolipids,Rhamnolipids,Nitrogen source,Carbon source,Iranian oil
- چکیده:
- چکیده انگلیسی: In this study 152 bacterial strains were isolated from the contaminated oils in the southwest of Iran. Hemolysis was used as a criterion for the primary isolation of biosurfactant producing-bacteria. Fifty five strains had haemolytic activity , among them tweleve strains were good biosurfactant producers by measuring surface tension and emulsification activity.Two microorganism showed the highest biosurfactant production when grown on paraffin and glycerol as the sole carbon source. Glycolipid production by the isolated bacterium using different carbon (n-hexadecane , paraffin oil, glycerol, molasses ) and nitrogen sources (NaNO3, (NH4)2SO4 and CH4N2O) was studied. Biosurfactant production was quantified by surface tension reduction, critical micelle dilution (CMD) , emulsification capacity (EC), and thin layer chromatogeraphy. Best result were obtained when using glycerol at a C/N ratio of 55/1 and sodium nitrate as nitrogen source. Production of the rhamnolipid, expressed by rhamnose was 4.2 g/L and the yield in relation to biomass, was Yp/x = 0.65 g/g. Additionally, physical-chemical characteristics of the spent broth with and without cells showed a low critical micelle concentration of 19 mg/L and a decrease in surface tension to 20 mN/m (%).
- انتشار مقاله: 14-07-1383
- نویسندگان: Hamid Rashedi,Mahnaz Mazaheri Assadi,Esmaeil Jamshidi,Babak Bonakdarpour
- مشاهده
- جایگاه : پژوهشی
- مجله: Environmental Energy and Economic Research
- نوع مقاله: Journal Article
- کلمات کلیدی: earthquake,crisis management,Socio-Psychological Vulnerability,Bam City,Theme Method
- چکیده:
- چکیده انگلیسی: Natural disasters in various forms have been identified as destructive phenomena during the life of earth planet and are also a serious threat to the inhabitants of the planet. Therefore, this issue leaded to the formation of a process called crisis management which includes activities occurring before, within and after the event to reduce the vulnerability. The country of Iran is considered as one of the world's affected countries from natural disasters due to its geographical location and climate diversity. In this research, the role of crisis management in reducing the socio-psychological vulnerability of affected citizens in 2003 earthquake of Bam city was investigated. Library and field study methods have been used to collect information in this study. Also, a qualitative-quantitative method was used to analyze the data by employing the theme method and consequently the most important factors affecting the citizen's socio-psychological vulnerabilities of Bam city after the earthquake were identified.
- انتشار مقاله: 23-05-1397
- نویسندگان: Seyed Rasoul Mousavi,Hamid Rashedi,Gholamreza Nabi Bidhendi
- مشاهده
- جایگاه : پژوهشی
- مجله: Environmental Energy and Economic Research
- نوع مقاله: Journal Article
- کلمات کلیدی: Air pollution,VOCs,Photocatalysis,Ethylbenzene,Annular Photoreactor
- چکیده:
- چکیده انگلیسی: The contaminated environment by various pollutants in the last decades is a serious concern for the governments and human societies all over the world. Volatile Organic Compounds (VOCs), emitted from a wide range of industries, are among such pollutants which can easily move in the air due to their volatile nature and are toxic and harmful to the environment and human health. Removal of gaseous ethylbenzene as an aromatic VOC using photocatalytic oxidation in an annular photoreactor packed with TiO2 nanoparticle-coated glass beads has been investigated in this research. The TiO2 nano-catalysts were characterized by XRD and FE-SEM. The removal efficiencies of about 75-100% could be yielded for the initial ethylbenzene concentrations up to 0.6 g/m3 in the UV irradiated reactor at a relatively low residence time. The inlet flow rate and initial ethylbenzene concentration were effective parameters on the removal efficiency and their increase caused reduction of removal efficiency. CO2 production in the photoreactor showed the mineralization of the pollutant during photocatalytic decomposition of ethylbenzene.
- انتشار مقاله: 29-05-1397
- نویسندگان: Morteza Kamaei,Hamid Rashedi,Seyed Mohammad Mehdi Dastgheib,Saeideh Tasharrofi
- مشاهده
- جایگاه : پژوهشی
- مجله: Analytical and Bioanalytical Electrochemistry
- نوع مقاله: Journal Article
- کلمات کلیدی: Wastewater,Fast Fourier transform stripping cyclic voltammetry,Mercury ions,Mesoporous silica,adsorbent,Modified SBA–15,Trithiane ligand
- چکیده:
- چکیده انگلیسی: As the electrochemical method, the Fast Fourier Transform (FFT) Stripping Cyclic Voltammetry detection method was designed for measurement and monitoring of adsorbed mercury ions by new modified adsorbent based on mesoporous silica as a new adsorbent. In this respect, SBA-15 as mesoporous silica and 1, 3, 5 Trithiane as effective modifier ligand were chosen, and the modification process was carried out physically. Continuing research application of modified mesoporous silica for the removal of mercury ions (Hg2+) from the aquatic environment in different pH, the weight of adsorbent and, stirring time as the major parameters were investigated and analysis of flow-injection was used as the major method for determination of adsorbed mercury ions by modified SBA-15. Also, a special computer numerical technique is used to calculate Hg response based on the total charge exchange at the electrode surface, where the currents were integrated into the range of reduction of Hg. The time for stripping was less than 300 ms. The results showed that the best Hg2+ ions removal conditions were achieved at the 15.0 mg of modified adsorbent, pH 5.0 and stirring time 15 min; Also the maximum percentage removal of Hg2+ ions and the capacity of the adsorbent were found to be 85% and 10.6 mg of Hg2+ ions /g modified SBA-15, respectively.
- انتشار مقاله: 17-01-1399
- نویسندگان: Mehdi Esmaeili Bidhendi,Gholam Reza Nabei,Hamid Rashedi,Naser Mehrdad
- مشاهده
- جایگاه : پژوهشی
- مجله: Advances in Environmental Technology
- نوع مقاله: Journal Article
- کلمات کلیدی: Bacteria,Crude Oil,Indigenous,Biosurfactant
- چکیده:
- چکیده انگلیسی: The present study investigated the isolation and identification of biosurfactant producing bacteria from Iranian oil wells. The biosurfactant production of bacteria isolates was evaluated and confirmed using hemolysis and emulsification tests. The biodegradation of crude oil was studied using GC and HPLC analysis. A total of 45 strains have been isolated. These strains showed less than a 40 mN m-1 reduction in surface tension. The effects of different pH (4.2-9.2), salinity concentrations (1%-15%), and temperatures (25-50) in biosurfactant production of isolated strains were evaluated. One of the strains (Bacillus sp. NO.4) showed a high salt tolerance and a successful production of biosurfactant in a vast pH range. Its maximum biomass production (about 3.1 g L-1 dry weight) was achieved after 60 hours of growth. The surface tension of the culture broth dropped rapidly after inoculation and reached its lowest value (36 mN m-1) during the exponential phase after about 36-48 hours of growth. The study of the GC graphs showed that higher aliphatic reduction occurred in fractions with C14 to C24 hydrocarbons. The depicted results of the HPLC graphs indicated a 100% degradation of chrysene and fluorine. In this study, we demonstrated the useful capacities of the isolates in removing oil pollutants and their application in MEOR in vitro.
- انتشار مقاله: 04-04-1393
- نویسندگان: Hamid Rashedi,Mahnaz Mazaheri Assadi,Akram Tabatabie
- مشاهده