فهرست مطالب

  • Volume:38 Issue:2, 2014
  • A2
  • تاریخ انتشار: 1393/03/12
  • تعداد عناوین: 12
|
  • R. Tayebi Khorami* Pages 95-103
    In this paper, we introduce the notion of multiplier in -algebra and study relationships between multipliers and some special mappings, likeness closure operators, homomorphisms and (-derivations in -algebras. We introduce the concept of idempotent multipliers in BL-algebra and weak congruence and obtain an interconnection between idempotent multipliers and weak congruences. Also, we introduce the special multiplier and study some properties. Finally, we show that if is a boolean algebra, then the set of all multipliers of is a -algebra under some conditions.
    Keywords: BL−algebra, MV−algebra, MV, center, multiplier, closure operator, Godel algebra
  • M. Mursaleen* Pages 105-109
    In this paper we introduce entire sequence spaces defined by a sequence of modulus functions. We study some topological properties of these spaces and prove some inclusion relations.
    Keywords: Modulus function, solid, monotone, entire sequences, paranormed space
  • A. Hosseini* Pages 111-115
    Let be a Banach algebra and a derivation. In this paper, it is proved, under certain conditions, that, where is the Jacobson radical of. Moreover, we prove that if is unital and is a continuous derivation, then, where denotes the set of all primitive ideals such that is commutative, denotes the set of all maximal (modular) ideals such that is commutative, and is the set of all non-zero multiplicative linear functionals from into. In addition, we present several results about the range of a derivation on algebras having the property ().
    Keywords: Derivation, derivation generator, pre, prime ideal, zero prime, property (B)
  • M. A. Naghipoor* Pages 117-121
    Let S be a monoid and X a class of S-acts which is closed under coproducts. The object of this article is to find conditions under which all S-acts have X-precovering. We have shown that the existence of torsion-free precovering implies the existence of torsion-free covering. This work is an attempt to further facilitate the study of the conjecture that all S-acts have flat cover.
    Keywords: Precover of act, cover of act, torsion free act
  • A. Abdollahi* Pages 123-132
    The main purpose of this article is to increase the efficiency of the least squares method in numerical solution of ill-posed functional and physical equations. Determining the least squares of a given function in an arbitrary set is often an ill-posed problem. In this article, by defining artificial constraint and using Lagrange multipliers method, the attempt is to turn -dimensional least squares problems into ones, in a way that the condition number of the corresponding system with -dimensional problem will be low. At first, the new method is introduced for and -term basis, then the presented method is generalized for -term basis. Finally, the numerical solution of some ill-posed problems like Fredholm integral equations of the first kind and singularly perturbed linear Fredholm integral equations of the second kind are approximated by chain least squares method. Numerical comparisons indicate that the chain least squares method yields accurate and stable approximations in many cases.
    Keywords: Lagrange multipliers method, chain least squares, ill, posed problem, integral equations
  • A. Hekmati* Pages 133-144
    Superconducting materials are capable of trapping extremely high magnetic fields. This property and Meissner effect of superconductors causes a levitation force between bulk superconductors and a permanent magnet (PM). This levitation force has possible industrial applications such as Permanent Magnet Guideways (PMG). Because of the high price of permanent magnets, the optimization of PMG design is necessary and beneficial. A heuristic optimization method has been proposed for the optimum arrangement and dimensions of permanent magnets in different structures of PMGs, which guarantee the satisfactory levitation performance. Therefore, finite element simulation, based on the estimation of penetration depth and self-inductance of the superconductor disk, has been utilized. The variation of the PMG features, such as its dimensions and cost versus the system parameters, such as the levitation height and the superconductor disk characteristics have been presented as the optimization results. Based on the optimization process outputs, PMG prototypes have been fabricated and tested successfully.
    Keywords: High temperature superconductor, levitation, optimization, permanent magnet guideway
  • Geochemical behavior of Mo and precious metals during supergene enrichment in the SarCheshmeh porphyry Cu deposit, Iran
    B. Shafiei* Pages 145-158
    Supergene oxidation-leaching and secondary sulfide enrichment in the SarCheshmeh porphyry Cu-Mo deposit generated a supergene profile to depths of 20 to 80 meters with oxide ore reserve about 22 Mt. @1.08% Cu and sulfides ore reserve~106Mt.@1.27% Cu. Geochemical distribution and behavior of trace metals associated with Cu namely Mo, Au, and Ag in the supergene profile of the SarCheshmeh were poorly understood and documented. To this aim, using a relatively large geochemical dataset along with theoretical data allowed distribution of the metals in the supergene profile to be clarified, and to be discussed behavior of Mo, Au, and Ag during supergene enrichment process of the SarCheshmeh deposit. Constraints on distribution and mobility of trace metals in the supergene environment of the SarCheshmeh deposit indicated that Au strongly enriched in the chalcocite zone. During supergene oxidation and leaching, Mo significantly remained in the leached cap, whereas Ag tends to be partially fixed in oxidized ore zone and locally enriched in chalcocite zone. Observed difference in the geochemical mobility of the metals is function of change in pH, Eh and metal-transporting capacity of supergene solutions. Under high acidic condition of supergene solutions which corresponded to oxidation of pyrite-rich primary ores (e.g., sericitized samples), mobility of Mo is greatly restricted with formation of ferrimolybdite in leached zone which has prevented supergene sulfide enrichment of Mo. This caused local enrichment of Mo (average~0.020 %) associated with Fe-oxides in leached ores which are supported by moderately positive correlation between Mo and Fe2O3 (r=+0.75) in such ores. Under such conditions, Au is strongly mobilized possibly as auric-chloride complexes rather than thiosulfates, and appreciably enriched in chalcocite zone. This is consistent with the low neutralizing capacity of the pyrite-rich primary ores along supergene solutions pathway and also semi-arid climate of the SarCheshmeh region. Unlike Au, soluble Ag in high acidic supergene solutions tends to be locally fixed in oxidized zone and to some extend enriched in chalcocite zone. This could relate to rapid decomposition of the halide complexes, consequently leaving silver as Ag-halide minerals, arjento-jarosite and/or native silver in oxidized ores without gold. This is supported by the negative correlation between Ag and Au values in oxidized ores (r= -0.28). Partial enrichment of Mo in chalcocite zone indicate that pH of supergene solutions derived from oxidation of pyrite-poor ores (biotitized ores) could remain above the stability field of ferrimolybdite (pH=5); this led to mobilization of Mo and locally enrichment of Mo in chalcocite zone. Where these conditions apply there may be local retention of Au in the form of native gold within leached ores.
  • A. H. Doulah* Pages 159-164
    Antibacterial, antifungal and antioxidant activities of methanolic crude extracts from aerial parts of four Arnebia species namely Arnebia fimbriopetala, Arnebia linearifolia, Arnebia garandiflora, Arnebia tubata were screened. Total phenolic contents were determined by Folin-Ciocalteu procedure and ranged from 2.2 ± 0.13 (A. fimbriopetala) to 1.6 ± 1.0 mg (Arnebia tubata) gallic acid µmol equivalent /g extract. The antioxidant activities were evaluated using 2, 2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging assays. All of the four Arnebia polar extracts showed good radical scavenging activity with an averaged IC50 value of 3.3 ± 0.15 µg/ml. DPPH assay results showed good correlations with the total phenolic contents of the plants, measured by the Folin-Ciocalteau assay. The antimicrobial activity was tested by using the disc-diffusion (DD) method and determining the minimal inhibitory concentration (MIC) using the macro dilution broth technique. The tested plants showed a mild antimicrobial activity against all nine tested strains. The best result belonged to the methanol extract of A. linearifolia against Bacillus pumilus with MIC value of 85µg/ml. Ampicillin, gentamicin and ketoconazole were used as references. The results obtained indicate that tested plant species from Arnebia genus may become important in the obtainment of noticeable sources of compounds with health protective potential, antioxidant and antimicrobial activity.
    Keywords: Arnebia, Antimicrobial, Antioxidant, Total Phenol, free radical
  • G. Forghani* Pages 165-173
    The mobility and bioavailability of trace elements in the agricultural soils are extremely important in assessing the risk of toxicity to the growing plants. A five step sequential extraction procedure (SEP) has been employed to study the speciation of As, Sb, Cr, Cu, Cd, Pb, Zn, Ni, Fe and Mn in 18 soil samples neighboring an industrial complex in Isfahan, central Iran. Enrichment factor (EF) calculation shows that in the soils studied, Cd and Fe are the most and the least enriched elements, respectively. Sequential extraction results indicate that although the total concentration of Ni, Sb, As, Cr and Cu is high, their concentration in the exchangeable plus carbonate fractions is rather low. This suggests that these elements are not easily transferred from soil to the plants. The high proportions of Cr, Cu and Fe in both organic matter and residual fractions, reduces the phytoavailability and the toxicity of these metals. On the other hand, Zn, Pb and Cd are strongly associated with exchangeable plus carbonate fractions, much more bioavailable than other studied elements. Good correlation between total contents and concentration of elements in each fraction indicates that the studied elements, excluding Fe, are mainly derived from the anthropogenic sources. Remediation measures and soil amendment practices are therefore recommended for the study site.
    Keywords: Bioavailability, speciation, agricultural soils, Isfahan, Iran
  • A. R. Sardarian* Pages 175-186
    Dodecylbenzenesulfonic acid (DBSA) was used as an efficient, cheap and stable Brønsted catalyst for acetylation of alcohols and phenols and formylation of alcohols under solvent-free conditions. Various primary, secondary and tertiary alcohols were acetylated with acetic anhydride as an acetylating agent under solvent-free conditions in the presence of catalytic amount of DBSA at room temperature. Also, formylation of alcohols was catalyzed by DBSA with ethyl formate in high to excellent yields. This method showed high selectivity in acetylation and formylation of various alcohols and phenols. DBSA was recovered and reused in four successive runs without significant deterioration in catalytic activity.
    Keywords: Dodecylbenzenesulfonic acid, acetylation, formylation, solvent, free, Reusable catalyst
  • N. M. Ganesan* Pages 187-191
    Titanium dioxide nanocrystals were synthesized by sol-gel method at room temperature. Titanium isoprophoxide and absolute ethanol were used as precursors to prepare the sol. The pH of the solution was adjusted by adding nitric acid and sodium hydroxide solution. The prepared TiO2 nanocrystals were annealed at 325°C, 425°C and 525°C respectively. The effect of pH on the surface morphology and structural properties of TiO2 nanocrystals were studied.
    Keywords: Citric acid, HPLC, partial recovery, optimization, physical, nutritional parameters
  • V. Suneetha* Pages 193-197
    India is one of the largest producers of onion in the world producing over 13,920,000 metric tons. Storage is a major problem which leads to spoilage, and microbes play an important role in the spoilage. In this present study, biotechnologically important strains have been isolated from the spoiled onions by using appropriate enriched media. Two potential strains were isolated and a brief Comparative study was done for fungal and bacterial strains in terms of citric acid production and the production of citric acid was also checked by using the designed media named as PAPS. HPLC analysis was performed to confirm the presence of citric acid in the culture medium. Partial recovery was done by filtration and precipitating oxalic acid as calcium oxalate. Optimization was done for various physical and nutritional parameters such as carbon source, temperature, pH and incubation period in order to recover maximum amount of citric acid.
    Keywords: Citric acid, HPLC, partial recovery, optimization, physical, nutritional parameters