University of Tehran Journal of Sciences, Islamic Republic of Iran 1016-1104 10 3 1999 09 01 SALICYLIC ACID INHIBITION OF GERMINATION, ETHYLENE PRODUCTION AND RESPIRATION IN COCKLEBUR SEEDS - 31428 EN Journal Article Salicylic acid (SA) inhibited germination of cocklebur (Xanthium pennsylvanicum Wlr), lower seeds, which are completely after-ripened and nondormant. SA also inhibited ethylene production during a pre-germination period of the seeds. Exogenous ethylene overcame the inhibtion of the seed germination by SA. Moreover, SA reduced respiration in pre-germinating whole seeds as well as excised axial tissues.S A was suggested to inhibit more severely cyanide-sensitive respiration than cyanideresistant respiration. The inhibition of both ethylene production and respiration by S A was thought to be the cause of prevention of cocklebur seed germination . The mechanism of the action of SA is discussed in the inhibition of cockelbur seed germination https://jsciences.ut.ac.ir/article_31428_0d87a1c0ff1500e3c4febc7582848dc2.pdf

University of Tehran Journal of Sciences, Islamic Republic of Iran 1016-1104 10 3 1999 09 01 STREPTOMYCES FRADIAE, A POTENT PRODUCER OF CHOLESTEROL OXIDASE - 31429 EN Journal Article Thirteen species of Streptomycetes, Arthrobacters and Mycobacterium were studied for the determination of a potential cholesterol oxidase producer. Only Streptomyces fradiae and Streptomyces rishiriences were found to be capable of producing this enzyme. Streptomyces fradiae was selected for the production of cholesterol oxidase and cultured in different media to find optimum media and conditions for enzyme production. The optimum media was found (g/Lit): glucose, 12; starch, 9; yeast extract, 6 ;peptone, 4; (NH ) SO ,7.5; Tween 80,0.5 with cholesterol, 2 as an enzyme inducer. 3 4 ?C w as the optlmum temperature for the production of cholesterol oxidase https://jsciences.ut.ac.ir/article_31429_2cb003b410ba24d03b9fc7fee7e2ad8a.pdf

University of Tehran Journal of Sciences, Islamic Republic of Iran 1016-1104 10 3 1999 09 01 SPECTROPHOTOMETRIC- STUDY OF THERMODYNAMICS OF SOME HEAVY METAL COMPLEXES OF 4-(2 - PYRIDYLAZO) RESORCINOL IN BINARY ACETONITRILEDIMETHYLFORMAMIDE MIXTURES - 31430 EN Journal Article The complexation reactions between 4-(2-pyridy1azo)-resorcinol and Cd ,H g and Pb io ns have been investigated in acetonitrile-dimethyEomamide mixtures at various temperatures using a spectrophotometric technique. The stoichiometry and the formation constants of the complexes formed in solution were calculated by computer refinement of absorbance-mole ratio data using nonlinear least-square program. The stoichiometries of resulting complexes are 1 : 1,l: 1 -2: 1 and 1 :2 (metalto - ligand ratio) for Pb H, g a nd Cd r espectively. Linear relationship is observed between equilibrium constants and the mole fraction of aceionitrile in the solvent mixtures. The ?H? and AS? of complex formation reactions were calculated from the temperature dependence of the stability constants. The effects of solvent composition on stability and thermodynamic parameters were discussed https://jsciences.ut.ac.ir/article_31430_8c4e1000e86191ffd2a27a253c0aad82.pdf

University of Tehran Journal of Sciences, Islamic Republic of Iran 1016-1104 10 3 1999 09 01 A CONVENIENT AND GENERAL SYNTHESIS OF THIADIAZOLO [2,3-C] [1,2,4] TRIAZINES - 31431 EN Journal Article Condensation and cyclization of 5-hydroxy- 1,2,4- thiadiazol-2-yl hydrazine 1 with pyruvic acid, phenacyl bromide, propargyl bromide and ally1 bromide afforded compounds 2,5,7 3, 4 ,6 and 8 respectively, Reaction of 1 with epichforohydrine afforded 4-hydroxy-N-[5-hydroxy- 1 ,3,4-thiadiazoly1] pyrazolidine 9 https://jsciences.ut.ac.ir/article_31431_5242ef6f489fc9c35ba357927f91a59f.pdf

University of Tehran Journal of Sciences, Islamic Republic of Iran 1016-1104 10 3 1999 09 01 SYNTHESIS OF NORBORNENE FURYL ESTERS AND THEIR ENZYMATIC KINETIC RESOLUTION BY PIG LIVER ESTRASE (PLE) - 31432 EN Journal Article The reaction of furylacrylic acid with cyclopentadiene in toluene gave the expected Diels-Alder endo-and exo-adductsin -1 : 1 ratio. The adducts were separated by iodolactonization method to provide 3-endo-(2'-furyl) bicyclo 12.2.11 hept-5-ene- 2-exo-carboxylic acid and 3-exo-(2'-fury1)bicyclo 12.2.11 hept-5-ene-2-endocarboxylic acid. Esterification of these acids by MeI / HMPA gave the expected methyl esters. Kinetic resolution of racemic endo- and exo-ester adducts by PLE(phosphate buffer, pH, 8) provided the related optically active isomers https://jsciences.ut.ac.ir/article_31432_9802a535bbdbcec203871db6d9595586.pdf

University of Tehran Journal of Sciences, Islamic Republic of Iran 1016-1104 10 3 1999 09 01 TRACE ELEMENT STUDY ON THE MIXED CARBONATE-PYROCLASTIC SEDIMENTS (LOWER MIOCENE, CENTRAL BASIN, IRAN) - 31433 EN Journal Article Geochemical investigations have permitted the refinement of the environmental interpretation of the f-Member of the Qum formation, Central Basin, Iran, which has been established through detailed microfacies (MF) analysis. The analysis revealed that the f-Member carbonates consist of eight distinct microfacies designated by the letters A through H. On the basis of petrographic characteristics and environmental significance, the studied MF have been interpreted in terms of depositional environments as follows: MF-A (basin); MF-B (lower slope); MF-C (reef flank); MFD (proximal talus), MF-E (organic reef); MF-F (lagoon); MF-G (restricted marine shoal), MF-H (restricted shelf). The concentrations of Ti, V, Fe, Co, Ni, Cu, Sr, Zr, U and Rb have been measured in limestones from outcrop samples of this formation. The analysis revealed a wide range of concentration both within and between different microfacies. A volcanic eruption in the nearby area located in the northeastern part of the sedimentary basin exerted an influence on trace element composition by supplying pyroclastic materials to carbonate sediments. In general, the basin microfacies is characterized by having the highest concentrations of Ti and Zr. The lower slope microfacies has the highest values of V, Fe, Ni, Cu, Sr, U and ratios of Ni /Co, Cu/Co and Ni/V, whereas the reef flank microfacies have only elevated concentrations of Co. All of these traces and elemental ratios are depressed in both proximal talus and reef rnicrofacies. The restricted marine shoal microfacies possesses elevated Rb values and the restricted shelf microfacies is characterized by a high concentration of Sr and elevated Cu , U and Rb values and show a slight increase in the Ti. Fe, V, Co, Ni, Zr values. https://jsciences.ut.ac.ir/article_31433_757be053baa902a28fef53520783d4c0.pdf

University of Tehran Journal of Sciences, Islamic Republic of Iran 1016-1104 10 3 1999 09 01 A RESEARCH NOTE ON THE SECOND ORDER DIFFERENTIAL EQUATION - 31434 EN Journal Article Let U(t, ) be solution of the Dirichlet problem y''+( t-q(t))y= 0 - 1 t l y(-l)= 0 = y(x), with variabIe t on (-1, x), for fixed x, which satisfies the initial condition U(-1, )=0 , (-1, )=1. In this paper, the asymptotic representation of the corresponding eigenfunctions of the eigen values has been investigated . Furthermore, the leading term of the asymptotic formula for - (x, (x)), (x) and is obtained where (x) is a negative eigenvalue of the Dirichlet problem on [-1, x] with fixed x < 0. https://jsciences.ut.ac.ir/article_31434_1f31606e625f642c0ed46405aada38a5.pdf

University of Tehran Journal of Sciences, Islamic Republic of Iran 1016-1104 10 3 1999 09 01 ON COMMUTATIVE GELFAND RINGS - 31435 EN Journal Article A ring is called a Gelfand ring (pm ring ) if each prime ideal is contained in a unique maximal ideal. For a Gelfand ring R with Jacobson radical zero, we show that the following are equivalent: (1) R is Artinian; (2) R is Noetherian; (3) R has a finite Goldie dimension; (4) Every maximal ideal is generated by an idempotent; (5) Max (R) is finite. We also give the following resu1ts:an ideal of R is uniform, if and only if, it is a minimal ideal; Ass (R) is exactly the set of all maximal ideals which are generated by an idempotent element of R https://jsciences.ut.ac.ir/article_31435_7f982c526e15dfa8be4c3eaa864c56ee.pdf

University of Tehran Journal of Sciences, Islamic Republic of Iran 1016-1104 10 3 1999 09 01 ON MULTIPHASE ALGORITHM FOR SINGLE VARIABLE EQUATION USING NEWTON'S CORRECTION METHOD - 31436 EN Journal Article This paper brings to light a method based on Multiphase algorithm for single variable equation using Newton's correction. Newton's method is derived through the logarithmic differentiation of polynomial equation. A correction term which enhances the high speed of convergence is hereby introduced. A translation of Newton's method to Total Step and Single Step Methods (T. S. M and S. S. M) respectively, forms the peak of discussion. Our method, so derived, is also discussed in the light of numerical evidence https://jsciences.ut.ac.ir/article_31436_8abb69b3d54bf7e21e4aff5f1047801e.pdf

University of Tehran Journal of Sciences, Islamic Republic of Iran 1016-1104 10 3 1999 09 01 A MODEL STUDY OF LASER ISOTOPE SEPARATION BY PHOTOIONIZATION OR PHOTODISSOCIATION PROCESS - 31437 EN Journal Article In this study, the selective photoexication of isotopic mixtures by laser light is investigated. Atomic and molecular methods are examined and rate equations are derived for both cases. Two and three step photoionization techniques are considered and rate equations are solved for ion yields. The molecular photodissociation process is also studied and the dependence of the dissociation product on the laser fluence is reported. The results of the developed model for SF molecule is compared with the other results and the agreement found in this comparison indicates the validity of the developed model https://jsciences.ut.ac.ir/article_31437_3632435cf99eec2a53ee7e4d8eeab451.pdf