PTD analysis of impedance structures

Based on an approximate dyadic diffraction coefficient, equivalent currents (ECs) are derived for computing the scattering by a finite-length impedance wedge of arbitrary angle. The derived equivalent currents are implemented in a standard general purpose physical theory of diffraction (PTD) code and results are presented demonstrating the accuracy of the formulation for a number of impedance and (dielectrically) coated structures. These include typical shapes such as plates, finite-length cones, and cylinders which have been partially or fully coated. The PTD implementation requires a dyadic physical optics diffraction coefficient which is presented in the appendix     

Template synthesis and spectroscopic studies of highly conjugated tetraiminetetraamide macrocyclic complexes from 1,2-diphenylethane-1,2-dione dihydrazone

A new class of tetraiminetetraamide macrocyclic (Ph4[20]tetraene, N8O4, and Ph6[20]tetraene, N8O4) complexes have been prepared through the metal ion controlled reaction of 1,2-diphenylethane-1,2-dione dihydrazone (DPEDDH) with succinic acid [ML1X2] or phthalic acid [ML2X2] [M=Mn, Co, Ni, Cu or Zn; X=Cl or NO3]. The structures of the complexes have been elucidated on the basis of i.r, 1H-n.m.r, e.p.r. and electronic spectral data and conductance, as well as magnetic, properties. An octahedral geometry is assigned for all the complexes, involving coordination of the all-imine nitrogens.     

Synthesis, ion-exchange properties and analytical applications of stannic selenoarsenate: Comparison with other heteropolyacid salts

Summary Stannic selenoarsenate samples have been prepared by adding a mixture which is 0.05 M in sodium arsenate and 0.05 M in sodium selenite to a 0.05 M solution of stannic chloride in different volume ratios at pH 1. Its ion-exchange properties, pH titration curves and X-ray pattern were studied. Adsorption behaviour of 24 metal ions in different solvent systems has been examined. The analytical importance of this material has been demonstrated by achieving the following binary and ternary separations: Hg²⁺-Cd²⁺, Co²⁺-Fe³⁺, Cu²⁺-Fe³⁺, Hg²⁺-Zn²⁺-Al³⁺, Hg²⁺-Cu²⁺-Al³⁺, Hg²⁺-Ni²⁺-Al³⁺, Hg²⁺-Zn²⁺-Fe³⁺ and Hg²⁺-Ni²⁺-Fe³⁺. A comparison of the ion-exchange properties of this material has also been made with some other tin(IV) based ion-exchangers.

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Synthese, Ionenaustauscher-Eigenschaften und analytische Anwendungen von Zinn-Selenoarsenat: Vergleich mit anderen Heteropolysalzen

Zusammenfassung Zinn-Selenoarsenat wurde durch Mischen von 0,05 M Natriumarsenat-, 0,05 M Natriumselenitund 0,05 M Zinn(IV)-Chlorid-Lösungen bei pH 1 in verschiedenen Verhältnissen hergestellt. Die Ionenaustauscher-Eigenschaften, pH-Titrationskurven sowie Röntgendiagramme wurden untersucht und das Adsorptionsverhalten von 24 Metallionen in verschiedenen Lösungsmittelsystemen geprüft. Die analytische Verwertbarkeit wurde an Hand der folgenden Trennungsmöglichkeiten gezeigt: Hg²⁺-Cd²⁺, Co²⁺-Fe³⁺, Cu²⁺-Fe³⁺, Hg²⁺-Zn²⁺-Al³⁺, Hg²⁺-Cu²⁺-Al³⁺, Hg²⁺-Ni²⁺-Al³⁺, Hg²⁺-Zn²⁺-Fe³⁺, Hg²⁺-Ni²⁺-Fe³⁺. Vergleiche mit anderen Ionenaustauschern auf Zinn(IV)-Basis werden ebenfalls beschrieben.

     

Microbial transformation of mestranol by Cunninghamella elegans

The microbial transformation of an oral contraceptive, mestranol (1) by Cunninghamella elegans yielded two hydroxylated metabolites, 6beta-hydroxymestranol (2) and 6beta,12beta-dihydroxymestranol (3). Metabolite 3 was found to be a new compound. These metabolites were structurally characterized on the basis of spectroscopic techniques.     

Isolation of onosmins A and B, lipoxygenase inhibitors from Onosma hispida

Onosmins A (1) and B (2), lipoxygenase inhibitors, have been isolated from Onosma hispida. Their structures were established as 2-[(4-methylbenzyl)amino]benzoic acid (1) and methyl 2-[(4-methylbenzyl)amino]benzoate (2) through spectroscopic studies, including 2D-NMR. The known compounds apigenin (3), 6,4'-dimethoxy-3,5,7-trihydroxyflavone (4), 6,7-dimethoxy-3,5,4'-trihydroxyflavone (5) and apigenin 7-O-beta-D-glucoside (6) are also reported for the first time from this species. Compounds (1) and (2) inhibited lipoxygenase (LOX, EC 1.13.11.12) enzyme in a concentration-dependent fashion with IC50 values of 24.0 and 36.2 microM, respectively. Lineweaver-Burk as well as Dixon plots and their secondary replots indicated that the nature of inhibition was purely a non-competitive type, with K(i) values 22.0 microM and 31.1, respectively.     

Lipoxygenase inhibiting constituents from Indigofera hetrantha

A lignan and two acylphloroglucinols have been isolated from the ethyl acetate soluble fraction of the whole plant of Indigofera hetrantha. Their structures have been assigned on the basis of spectral analysis including 1D and 2D NMR techniques. Compounds 1-3 displayed promising inhibitory potential against enzyme lipoxygenase in concentration-dependent manner.     

Transfer of radioactivity from soil to vegetation in Rechna Doab, Pakistan

In Rechna Doab, samples of the most common vegetation, perennial grass Desmostachya bipinnata (dab), were collected along with soil samples from 29 sites. Natural radioactivity of 22?Ra, 232Th/22?Ac and ??K was measured by using high purity germanium-based gamma ray spectrometer. Activity concentration levels of 22?Ra, 232Th/22?Ac and ??K in soil were found to be 46.8 ± 6.2 (36.0-57.6), 61.4 ± 5.9 (48.2-73.2) and 644.8 ± 73.9 (537.7-868.4) Bq kg?1 (dry mass), respectively, and those in vegetation were 2.74 ± 1.70 (1.00-6.39), 2.24 ± 0.59 (1.56-2.61) and 172.72±113.37 (53.14-469.24) Bq kg?1 (dry mass), respectively. The measured values of the activity concentration in vegetation are comparable with some other international data. Calculated soil to vegetation transfer factors of 22?Ra, 22?Ac and ??K were 0.06 ± 0.03 (0.02-0.14), 0.04 ± 0.01 (0.03-0.04) and 0.26 ± 0.16 (0.09-0.69). The mean outdoor absorbed dose rate in air for the area under study was determined as 8.22 nGy h?1 and the mean indoor absorbed dose rate in air was 11.52 nGy h?1. The total annual effective dose to the general public from the vegetation was found to be (0.02-0.16) mSv, which is below the recommended limit value of 1 mSv y?1 for the general public. The dab vegetation under study was found to be radiologically safe for the population and environment.