Showing papers by "Islamic Azad University published in 1998"
TL;DR: In this article, the physicochemical characteristics of paper mill effluents and the accumulation of heavy metals (Cu, Zn, Pb, Co, Cd, Cr, and Ni) in the soil and different parts (root, leaf, and seed) of the paddy crops growing in the irrigated area are described and compared with the soil.
Abstract: Extensive irrigation by the effluents released from a paper mill near Nanjangud have led to the accumulation of heavy metals in the soil and different parts of the paddy crops. In this paper, the physicochemical characteristics of paper mill effluents and the accumulation of heavy metals (Cu, Zn, Pb, Co, Cd, Cr, and Ni) in the soil and different parts (root, leaf, and seed) of the paddy crops growing in the irrigated area are described and compared with the soil and paddy crops irrigated by natural waters (unpolluted). Chemical and biological oxygen demands of wastewater were found to be 437 and 1070 ppm respectively, which are beyond the tolerance limits set by Indian standards. The total dissolved and suspended solids are 1754 and 900 ppm respectively. The concentration of heavy metals (except Zn) in the seeds is remarkably less than that in the roots and leaves of the paddy crops. The heavy metal uptake by plants shows the greatest accumulation of Cu, Cr, Co, and Pb in the roots; Cd and Ni in the leaves; and Zn in the seeds of rice. The heavy metal content of the soil and their total uptake by paddy roots has the relation: Pb>Zn>Cu>Cd and Pb>Cu>Zn>Cd. Survival of paddy crops irrigated by polluted waters indicates tolerance to toxic heavy metals. In conclusion, since in many tropical countries the common diet of people is rice, the accumulation of toxic heavy metals in rice may lead to health disorders.
55 citations
TL;DR: The results show the role of the ionic strength of the non-inhibitory salt solution on the stability of penicillin G acylase, especially for long-time storage and operation.
16 citations
TL;DR: In this paper, the AM1 semi-consistent field molecular orbital method was employed to calculate structure optimization, conformational and configurational interconversion pathways for open-chain carbodiimides 1a-h.
Abstract: An investigation employing the AM1 semiempirical self-consistent field molecular orbital method to calculate structure optimization, conformational and configurational interconversion pathways for open-chain carbodiimides 1a-h has been undertaken. These calculations show that the stereoisomerization takes place by trans -rotation. The calculated structural parameters and racemization energy barriers are in fairly good agreement with experimental results. For 1,3,4,6-tetraazacyclonona-1,2,4,5-tetraene ( 2 ), the meso -diastereoisomer is calculated to be 17.9 kJ mol −1 more stable than the (±)-isomer. The boat conformation of meso - 2 is 8.3 kJ mol −1 more stable than the chair form. The ground-state conformation of (±)- 2 is the axial symmetrical twist-boat conformation, which is 17.9 kJmol −1 less stable than the boat conformation of meso - 2 . Configurational interconversion between the meso - and (±)-diastereoisomers of 2 requirs about 57.9 kJ mol −1 .
3 citations
TL;DR: In this article, the Wittig reaction was used to produce 4-phenyl-N-hydroxypyrrole-2,3-dicarboxylates in moderate yields.
Abstract: Protonation of the reactive intermediates generated in the raction between dalkyl acetylenedicarboxylates and triphenylphosphine by isonitrosoacetophenone leads to vinyltriphenylphosphonium salts, which undergo intramolecular Wittig reaction to produce dalkyl 4-phenyl-N-hydroxypyrrole-2,3-dicarboxylates in moderate yields.
2 citations
13 Nov 1998
TL;DR: In this article, an optimum operation condition for a pulse and continuous wave HCN laser is obtained for both a single and multiple-antenna HCN-Laser with a wavelength of 337 micrometer and 311 micrometers, respectively.
Abstract: FIR Lasers have been widely used in a various field of physics. HCN Lasers are the most popular Laser in this region for their relatively high power output where other sources of radiation are weak. HCN Laser works at wavelength of 337 micrometer and 311 micrometer. An optimum operation condition for a pulse and continuous wave HCN Laser is obtained.
2 citations
TL;DR: In this paper, the AM1 semi-empirical SCF MO method was employed to calculate structure optimization and conformational interconversion pathways for Z-cyclonona-3-ene-1,5-diyne (1), Z- cyclonna-3ene-l, 5-dyne (2 ), and Zcycloundeca-3eneca-1-ene, 1,5diyn (3 ) has been undertaken.
Abstract: An investigation employing the AM1 semi-empirical SCF MO method to calculate structure optimization and conformational interconversion pathways for Z-cyclonona-3-ene-1,5-diyne ( 1 ), Z-cyclodeca-3-ene-l,5-diyne ( 2 ), and Z-cycloundeca-3-ene-1, 5-diyne ( 3 ) has been undertaken. The plane-symmetrical half-chair conformation of 1 is calculated to be 23.8 kJ mol −1 more stable than the planar C 2 v transition-state geometry. Compound 2 has two energy-minimum conformations with the twistboat ( C 2 ) form being 31.1 kJ mol −1 more stable than the twist ( C 1 ) geometry. The calculated energy barrier for interconversion of C 2 and C 1 conformations is 37.4 kJ mol −1 . The unsymmetrical twist-boat form of 3 is calculated to be the most stable conformation. The twist-boat geometry can undergo two degenerate processes to achieve a time-averaged symmetry of C 2 v .
2 citations
01 Jun 1998
TL;DR: In this paper, an experimental study on the disruptive instability occurring in the Iran-Tokamak 1 (IR-T1) in comparison with stellarator experiments, particularly CLEO machine, is presented.
Abstract: Summary form only given, as follows. The understanding of the collapse phenomena in toroidal plasmas is an essential subject, because such events determine the boundaries of the plasma parameters and the stationary operation. One of the possible candidate of the mechanisms that causes the collapse is the Mirnov instability. If the rotational transform at the boundary of low shear stellarator plasmas, such as CLEO and W7-AS, with and without a net toroidal current approaches low rational values (1/2 and 1/3), Mirnov data indicate the presence of modes with the expected poloidal harmonic m. Moreover, in tokamaks, the disruptive instability is often preceded by strong Mirnov oscillation (usually m=2 or m=3) in the outer regions of the plasma. This article presents an experimental study on the disruptive instability occurring in the Iran-Tokamak 1 (IR-T1) in comparison with stellarator experiments, particularly CLEO machine. It is found that the fluctuations of the poloidal mode numbers m=2 and 3 at the rational surfaces q=2 and 3 are responsible for most of global magnetohydrodynamic (MHD) activities in low shear stellarators and tokamaks. Diagnostics and operational region with and without l=2 and l=3 helical fields of the IR-T1 tokamak have already been presented.
2 citations
TL;DR: In this article, MNDO, AM1 and PM3 semi-empirical SCF MO calculations are used to calculate the structure optimization and configurational features of cyclopentadeca-1,2,4,5,7,8,10,11,13,14-decaene (4).
Abstract: MNDO, AM1 and PM3 semi-empirical SCF MO calculations are used to calculate the structure optimization and configurational features of cyclopentadeca-1,2,4,5,7,8,10,11,13,14-decaene (4). The combination of three allenic units of the same chirality and two units of opposite chirality yields an enantiomeric pair (RRSRS and SSRSR) of C2 symmetry, which is the most stable configuration of 4.