text article 1997 eng Two hundred samples were taken from various sites in Iran, including coal storage areas, waste water in the Tabas and Zirab coal mines, and sulphur containing acid springs in Ramsar and Abask , and were screened for Thlobacillus ferruuxidans. During this investigation , seven strains were isolated which could oxidize sdphm , pyrite , thiosdphate and ferrous iron as the sole energy source. Macroscopic, microscopic and biochemical studies showed that the isolates were T. f e r r ooxidans University of Tehran 1016-1104 8 v. 3 no. 1997 https://jsciences.ut.ac.ir/article_31248_1ae1ce1f984a64eede9b43824434a011.pdf text article 1997 eng The interaction between sodium and calcium, magnesium and calcium and the combined effect of sodium, magnesium and calcium was observed on the growth and ion uptake of Hippophae rhamnoides L. The results demonstrated that an addition of sodium with calcium, (set a, Na 2.5 + Ca 5 mM) showed prominent increase in fresh weight of roots and shoots. The dry weight (average) of roots decreased and that of shoots increased but the percent dry weight of both roots and shoots decreased following an increase in percent water content. An addition of magnesium with calcium, (set b, Mg 2.5 + Ca 5 mM) showed an increase in fresh and dry weight (average and percentage of root and shoot), while percent water content decreased. The addition of sodium and magnesium with calcium , (set c, Na 2.5 +Mg 2.5 + Ca 5 mM) showed an increase in fresh and dry weight (average) of roots and shoots, while percentage dry weight of roots decreased and that of shoots increased and the percentage water content of roots increased and that of shoots decreased. The treatments of sets a, b and c increased the uptake of all ions studied. However, a difference in ion uptake within treatments occurred. It appears that the presence of calcium mitigates the adverse effects of sodium and magnesium by preventing their uptake and enhances the uptake of potassium University of Tehran 1016-1104 8 v. 3 no. 1997 https://jsciences.ut.ac.ir/article_31249_f2848db8d343db9371dd09349b37f438.pdf text article 1997 eng The mechanistic aspects of the electrochemical reduction of U(V1) nitrate at a mercury electrode in chloroform, using three different supporting electrolytes, are described. In the presence of tetrabutylarnmonium perchlorate (TBAP) as a neutral electrolyte, UO (NO ) , reduced in two irreversible electrochemical steps to form a U(V1)-U(V) binuclear complex and U(IV), respectively. In the presence of 0.75 M piperidinium perchlorate (PP) + 0.25 M piperidine (P) as supporting electrolyte, the reduction of U0 ( NO ) occurred according to a one-electron irreversible process to U (V). The same behaviour was observed in the presence of 0.5 M tributylamrnonium perchlorate + 0.3 M tributylamine. The diffusion coefficients of U(VI) and U(VI)- U(V) binuclear complex determined by chronoamperometric measurement are 8.8 cm s and 5.37 10 cm s respectively University of Tehran 1016-1104 8 v. 3 no. 1997 https://jsciences.ut.ac.ir/article_31250_4faf9da37077eb035bc9b26042482069.pdf text article 1997 eng Hantzsch 1 ,4- dihy&opyridines are rapidly oxidized to the corresponding pyridine derivatives using zinc chlorochromate nonahydrate [Zn(C1CrO ) .9H O] in dichloromethane at room temperature. In addition to aromatization, no loss of the 4- substituent is observed University of Tehran 1016-1104 8 v. 3 no. 1997 https://jsciences.ut.ac.ir/article_31251_b4b835f5f1b3b61ead46c1e56c9c1c93.pdf text article 1997 eng Treatment of acetyl- 1,4-benzoquinone with isoprene gave the corresponding regioselective adduct (I). Rearrangement of the adduct (1) in pyridine and methanol gave 2-acetyl-5, 8-dihydro-6-methyl- 1,4-dihydroxynaphthalene (2). Silver oxide oxidation of the rearranged product (2) gave 2-acetyl-5,8-dihydro- 6-methyl- 1,4naphthalenedione (3). Regioselective addition of trans-piperylene to this compound (3) gave the c&esponding adduct (4). Treatment of the resulting cycloadduct (4) with manganese dioxide gave the regiospecific 1,6- dimethyl-9, 10-anthracenedione (5). Each of the foregoing reactions proceeds in high yield University of Tehran 1016-1104 8 v. 3 no. 1997 https://jsciences.ut.ac.ir/article_31252_63ff1be82cae7709c98cda1cdcb6a90a.pdf text article 1997 eng Papaverfugax Poiret population Tarom was shown to contain one major alkaloid, mecamberine (0.4%), and six minor alkaloids, roemerine, pronuciferine, protopine, thebaine, nornuciferine and salutaridine. Nornuciferine was detected for the first time in P. fugax University of Tehran 1016-1104 8 v. 3 no. 1997 https://jsciences.ut.ac.ir/article_31253_c94f96a5f6a55b858ab83d349f279334.pdf text article 1997 eng X-ray photoelectron and high resolution electron energy loss spectroscopic (XPS-HREELS) studies have shown that the adsorption of carbon dioxide at Mg(100) surfaces at 80K is followed by a dissociative reaction leading to the formation of a metastable surface carbonate above 80K. The formation of a carbonate species is proposed to proceed through oxidation of C0 (g) by an active oxygen surface transient O formed by dissociation of dioxygen or dissociative chemisorption of carbon dioxide. The O(1s) data establish that oxidation and carbonate formation occur simultaneously suggesting that dissociative chemisorption involves the formation of an oxygen adatom which can either form oxide or react with C0 to form carbonate University of Tehran 1016-1104 8 v. 3 no. 1997 https://jsciences.ut.ac.ir/article_31254_098b846e6e9a0730aaaf7526051f2c11.pdf text article 1997 eng Detailed petrographic, geochemical and strontium isotope studies, combined with field observation and rnicrofacies investigations indicate that syngenetic celestite at the base of Asmari Formation at the Bangestan anticline, Behbahan region, was deposited directly from Tertiary seawater in an intrasupratidal to supratidal environment. During diagenesis, the precipitated celestite underwent several textural and mineralogical modifications, the most important of which was the formation of diagenetic crystallization rhythmites. Fluid inclusion geotherrnometry and rmR analyses suggest that the fluid medium, in which recrystallization of the celestite took place, was among other constituents rich in immature hydrocarbons. It is demonstrated that the celestite concretions were subjected to several low temperature thermal events, the maximum of which did not exceed 255?C University of Tehran 1016-1104 8 v. 3 no. 1997 https://jsciences.ut.ac.ir/article_31255_b2209d6e9274b5e791580c45037c0905.pdf text article 1997 eng In this paper, we adapt the operational Tau Method for personal computers and apply it to a system of two nonlinear second order ordinary differential equations which are related to general relativity. The interesting behaviour this problem exhibits in its numerical treatment is discussed. In this problem, we try to use the Tau perturbation term to locate the correct solution of this nonlinear problem. The results of this experiment and those which are going to be given in another paper show that in some problems the effect of nonlinearity could prevent the correct solution from being located properly University of Tehran 1016-1104 8 v. 3 no. 1997 https://jsciences.ut.ac.ir/article_31256_d714d599c2c8a5a31918b2326233d014.pdf text article 1997 eng Let D be a division ring with centre K and dim, D< ? a valuation on K and v a noninvariant extension of ? to D. We define the initial ramfication index of v over ?, ?(v/ ?) .Let A be a valuation ring of o with maximal ideal m, and v , v ,…, v noninvariant extensions of w to D with valuation rings A , A ,…, A . If B= A , it is shown that the following conditions are equivalent: (i) B is a finite A-module, (ii) B is a free A-module, (iii) [B/mB: A/m] = [D: k], (iv) e(v / ?) f(v / ?)= [D: K] and ? (v / ?)= e(v / ?). It is also proved that if ? (v/ ?) = e(v/ ?), and any of (i) - (iv) holds, then v is invariant University of Tehran 1016-1104 8 v. 3 no. 1997 https://jsciences.ut.ac.ir/article_31257_15f75ef1d10234576e559849154d710f.pdf text article 1997 eng A more detailed analysis is made of the energy spectrum of the diffuse component of extragalactic gamma rays over the range of 0.3- 10 GeV, obtained fromthe EGRET instrument at the Compton Gamma Ray Observatory. The derived excess energy spectrum of high galactic latitude, b > 60°, using intercept method shows that it is correlated with Virgo cluster (over lsr) and average Virgo intensity is about 20 percent of total diffuse extra galactic intensity. The Virgo predicted models seem to be overestimated University of Tehran 1016-1104 8 v. 3 no. 1997 https://jsciences.ut.ac.ir/article_31258_9633a4a76c2f86667c0aed8e8f61a9d8.pdf text article 1997 eng A simple analytical system suitable for nephelometric measurements is introduced in this article. The electronic and optical components are simplified so that the apparatus is easily assembled from materials that are generally available. This instrument is designed for the efficient measurement of anions, and microgram quantities of ions may be determined by a convenient method of titration. Using this systarn, the ion detection is performed on several species, and the preliminary results are reported here. The results from the determination of sulfate and chloride ions show a good detection limit(10 M), and a linearity range of 10 -10 M University of Tehran 1016-1104 8 v. 3 no. 1997 https://jsciences.ut.ac.ir/article_31259_f449b35761ae503aca167a5eb48d1e9c.pdf