Journal of Sciences, Islamic Republic of Iran
Year:2002 | Volume:13 | Issue:2|Papers Count:19

Mycobacterium smegmatis PTCC 1307 (CIP 73.26) was used as a microbial agent to produce androsta-1,4-diene-3,17-dione (ADD) and androst-4-ene-3,17- dione, two useful precursors in the synthesis of steroid drugs. The side chain of cholesterol, as the substrate, was selectively cleaved in the presence of five enzyme inhibitors. An intermediate structure with intact side chain, cholest-4-ene- 3-one, was also detected and purified.

Acetone fractionated peroxidase from crude extract of Brassica oleracea leaves (Cabbage) was purified in three steps on chromatographic columns, using Sp-Sepharose, DEAE-Sepharose and Con A-Sepharose. The specific activity of purified main isoenzyme (BOC-POD) is 1887 u/mg protein with RZ: 3.1, which is 172 times more than the RZ of crude extract with 4.3% recovery. The molecular weight of BOC-POD is about 45,000 Dalton. Maximum pH, thermal activity and stability of this purified enzyme are also determined. Km of this isoenzyme was measured by Linewearver-Burk curve for O-dianisidine towards H2O2. This purified enzyme could be used in manufacturing diagnostic kits.

A series of non-cyclic polyethers with different end groups and chain length were used for the extraction of lithium salt from aqueous into various organic phases viz. Chloroform, Carbon tetrachloride, 1,2-dichloroethane, to study the influence of structural variations within the extractant molecule upon the extraction selectivity and efficiency. The ionophores used were viz. DEG (I), DEGDME (II), DEGMBE (III), DEGDBE (IV), DEGDB (V), EE (VI), ME (VII), Cryptofix (VIII), TEG (IX), TrEG (X). The trend of extraction is IV > III > I ≈ II > VI > VII > V > VIII ≈ IX ≈ X. The DEGDBE proved to be the most efficient extractant for the lithium ion.

A simple and sensitive extraction-spectrophotometric method for rapid and accurate determination of benzocaine in pure and dosage forms was developed. Benzocaine was effectively extracted as a 1:1 ion pair complex with dicyclohexyl- 18-crown-6 and calmagite in acidic media into chloroform, followed by spectrophotometric determination at 486 nm. Molar absorptivity of the ternary complex at this wavelength was 5.25×103 l mol-1 cm-1. Beer’s law was obeyed over the range 1.65-132 μg/ml of benzocaine and the minimum detectable amount of the drug was 0.6 μg/ml. The method was successfully applied to the determination of benzocaine in a cream sample.

A new technique of coupled electrodeposition-electrothermal Atomic Absorption Spectrometry (AAS) method has been developed to study chromium speciation. Speciation of Cr (VI)/Cr (III) is carried out by electrodeposition at uncontrolled applied potentials, followed by removal of spent electrolyte and atomisation. At Eappl = 0.5-10.0 V and using codeposition with Hg (and without Pd coating), only Cr (VI) is reduced to Cr (III) and accumulated as Cr (OH)3 by absorption onto mercury film on the graphite furnace. Total chromium is measured by electrodepositing at 10.0 V without Hg but on the renewable Pd substrate from 0.5 M NaCl and 1% H2SO4. It has been demonstrated that chromium speciation can be achieved in samples of 0.5 M NaCl, using acetate buffer to adjust pH to 4.7. The results also will be given for attempted chromium speciation studies by in situ deposition onto Pd-coated furnace. At all applied voltages between 2.0- 10.0 V in 0.02% H2SO4 Cr (III) is reduced to chromium metal and deposited onto the Pd substrate more efficiently than Cr (VI), but the difference is not sufficient for complete discrimination of two chromium forms. The effect of SO4 2- ion concentration and of pH on the yield of deposition were studied for each form of chromium. It was shown that from 1% H2SO4 both forms of chromium deposited quantitatively. Apart from achieving speciation, background signal due to high concentration of NaCl in the sample was completely eliminated by the proposed technique. At the same time a two-fold improvement in sensitivity of the determination was achieved with respect to the conventional electrothermal AAS technique.

Treatment of 5,8-dihydroxy-1-tetralone (9) with either 2,3-dichloro-5,6- dicyano-1,4-benzoquinone (DDQ) in refluxing benzene or silver (I) oxide in refluxing 1,4-dioxane afforded juglone (5-hydroxy-1,4-naphthoquinone) (1) in good yield. With manganese dioxide in dioxane the tetralone gave a mixture of juglone and naphthazarin (5,8-dihydroxy-1,4-naphthoquinone) (3), the proportion of naphthazarin being increased by the presence of water. Silver (I) oxide in 1,4- dioxane converted 9,10-dihydroxy-1-oxo (14),9,10-dihydroxy-1,5-dioxo (15), and 1,8-dioxo-1,2,3,4,5,6,7,8-octahydro anthracene (16) into, respectively, 1-hydroxy- 5,6,7,8-tetrahydro (23), 1,5-dihydroxy (6), and 1,8-dihydroxy-9,10-anthraquinone (4), in high yield. Mechanisms for these transformations are discussed.

The Etive igneous complex has intruded into Dalradian and Moine metasedimentary rocks in Devonian. Main rock types of the complex are granodiorite, monzodiorite, monzogranite, granite and diorite. Geochemical studies show that the magmas were of high K calc-alkaline, I-type and metaluminous nature. Application of discriminant diagrams to the Etive rocks indicates a possible within-plate tectonic setting for the complex. Considering the magma type and trace element geochemistry along with behaviour of studied samples on tectonomagmatic discriminant diagrams, contributions of subduction related materials and materials with within-plate affinities are likely in generation of the Etive igneous complex.

Mineral paragenesis of rodingitized basic rocks of Iranian ophiolites are presented and metasomatic reactions between Ca+2 bearing aqueous fluids issued during serpentinization of host ultramafic rock – with magmatic minerals of basic rocks leading to present paragenesis of rodingites are discussed. It is concluded that Ca+2 rich aqueous fluid in equilibrium with serpentinite has high Ca+2 chemical potential to react with magmatic minerals of basic dykes resulting in lowering the free energy of system, appearance of a new mineral paragenesis and total or partial conversion of basic dykes to rodingites. A feedback mechanism is proposed to account for inter-relationship of serpentinization and rodingitization.

In this paper, we use the continuous Legendre wavelets on the interval [0,1] constructed by Razzaghi M. and Yousefi S. [6] to solve the linear second kind integral equations. We use quadrature formula for the calculation of the products of any functions, which are required in the approximation for the integral equations. Then we reduced the integral equation to the solution of linear algebraic equation.

The existence of shift for periodically correlated processes and its boundedness are investigated. Spectral criteria for these non-stationary processes to have such shifts are obtained.

The variations of the electrical conductivity with temperature and electric field of the ternary alloy of gallium, aluminium and arsenic (Al0.75Ga0.25As) with atomic compositions of 99/1 and 98/2 have been investigated. The electrical conductivity of the alloy increases with temperature according to the relation, σ =  σ0 exp (−є/kT). The activation energy calculated from this empirical relation is 1.42±0.01 eV. The investigation of the variation of electrical conductivity with electric field of the samples reveals that in the low field region (< 1,400 V/m), the conduction is ohmic while in the high field region (> 1,400 V/m), the results are interpreted in terms of space charge limited currents.