در هنگام جستجو کلمه در قسمت عنوان میتوانید کلمات مورد جستجو را با کاراکتر (-) جدا کنید.
کاربرد نوع شرط:
- جایگاه : پژوهشی
- مجله: Iranian Journal of Biotechnology
- نوع مقاله: Journal Article
- کلمات کلیدی: Isolation,Bioleaching,Thiobacillus spp,Leptospirillum spp,Mixed cultures
- چکیده:
- چکیده انگلیسی: Pure mesophilic bioleaching bacteria were isolated to compare their potential for oxidizing ferrous and sulfur
in synthetic media and copper extraction from low grade ore with mixed bacterial community. A total of 160 samples were collected from various sites of different mines. Enrichment and isolation of ferrous-/sulfur-
oxidizing bacteria were done in specific media. A total of 68 isolates were screened, 63 of which oxidized
Fe2+; the rest oxidized sulfur at different rates. Three important types of bacteria were identified to be
Thiobacillus ferrooxidans, Thiobacillus thiooxidans and Leptospirillum ferrooxidans on the basis of morphological and physiological tests. The oxidation characteristics of both sulfur and ferrous were studied in pure isolates and mixed cultures. Oxidation behavior for all pure Fe2+-oxidizing isolates was properly modeled with Monod equation and a specific Fe2+-oxidation rate (μm) of 0.076 to 0.737 / h was reached. The rate of sulfur oxidation for pure sulfur-oxidizing isolates was 9 mg of sulfur / l/ h. Results of ferrous- or sulfur- oxidation for mixed cultures were in agrement with their bacterial community and pure isolates. The role of bacteria in releasing of copper was evaluated for pure isolates and mixed cultures. The results obtained showed that the simultaneous use of three types of isolates leads to more copper release and lower acid consumption compared to other communities. The positive effect of the initial concentration of Fe2+ showed that major portion of copper extraction is via indirect reactions.- انتشار مقاله: 10-04-1382
- نویسندگان: Hamid Zilouei,Seyed Abbas Shojaosadati,Rasoul Khalilzadeh,Bahram Nasernejad
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Chemistry and Chemical Engineering
- نوع مقاله: Journal Article
- کلمات کلیدی: PCA,ICA,Regulatory signal,Biological network,MLP NN
- چکیده:
- چکیده انگلیسی: The biologists now face with the masses of high dimensional datasets generated from various high-throughput technologies, which are outputs of complex inter-connected biological networks at different levels driven by a number of hidden regulatory signals. So far, many computational and statistical methods such as PCA and ICA have been employed for computing low-dimensional or hidden representations of these datasets, but in most cases the results are inconsistent with underlying real network. In this paper we have employed and compared three linear (PCA and ICA) and non-linear (MLP neural network) dimensionality reduction techniques to uncover these regulatory signals, from outputs of such networks. The three approaches were verified experimentally using the absorbance spectra of a network of seven hemoglobin solutions, and the results revealed the superiority of the MLP NN to PCA and ICA. This study shows the capability of the MLP NN approach to efficiently determine the regulatory components in biological networked systems.
- انتشار مقاله: 11-12-1383
- نویسندگان: Alireza Zomorrodi,Bahram Nasernejad,Jahanshah Kabudian
- مشاهده
- جایگاه : پژوهشی
- مجله: Iranian Journal of Chemistry and Chemical Engineering
- نوع مقاله: Journal Article
- کلمات کلیدی: Fermentation,Iranian black tea,Orthodox,CTC,Theaflavin,Thearubigin,Optimum time
- چکیده:
- چکیده انگلیسی: The optimum fermentation times of black tea manufactured by two systems of Orthodox and CTC (cut, tear & curl) were investigated by measuring the quality parameters of black tea, like: theaflavin, thearubigin, highly polymerized substances and total liquid colour during the fermentation stage. Optimum fermentation times from the beginning of fermentation were determined to be 60 min and 150 min for the fine and coarse tea of orthodox manufacturing, respectively. The optimum fermentation time of CTC tea process was 30 min. Most theaflavin content of Orthodox and CTC processes were 0.63 and 0.82 percent of the total dried solids of infusions, respectively. Total color of CTC manufacturing was 16% higher than Orthodox process.
- انتشار مقاله: 12-12-1382
- نویسندگان: Masoud Hafezi,Bahram Nasernejad,Farzaneh Vahabzadeh
- مشاهده
- جایگاه : پژوهشی
- مجله: Advances in Environmental Technology
- نوع مقاله: Journal Article
- کلمات کلیدی: Biosorption,Bagasse,Isotherm,kinetic,Styrene
- چکیده:
- چکیده انگلیسی: In this work, styrene removal from wastewater by using sugarcane waste (bagasse) as an adsorbent was studied. Equilibrium isotherms and kinetics were determined; the effects of bagasse particle size and concentration, solutions pH, and temperature on the biosorption of styrene were studied in batch experiments. Adsorption equilibrium data was successfully fitted to Langmuir isotherms (R2=0.986) and Freundlich isotherms (R2=0.96). Also, the kinetics of biosorption was fitted to pseudo-second order equations (K2=0.00146 g mg-1 min-1, qe=24.5 mg g-1 for particle size range of 88-105 μm).
According to the obtained results, an empirical equation was presented that could be used to calculate the percentage of styrene adsorption. The results showed that an increase in temperature caused a decrease in styrene removal. Moreover, maximum uptake was observed with NaOH-treated bagasse. It was found that an increase in average particle size decreased the biosorption rate. According to the calculated heat of adsorption, this sorption can be classified as a chemical biosorption. The optimum uptake was determined to be 88% at a pH equal to 12.1, a temperature of 35 oC, a particle size of 420-500 μm, and a bagasse concentration of 1 g L-1.- انتشار مقاله: 11-07-1393
- نویسندگان: Mehdi Hassanzadeh,Narges Fallah,Bahram Nasernejad,Rouein Halladj
- مشاهده