Isolation of NO(3)(-)-N as 1-phenylazo-2-naphthol (Sudan-1) for measurement of delta(15)N

The conversion of nitrate (NO(3)(-)) to 1-phenylazo-2-naphthol (Sudan-1) has been examined as a method for natural abundance measurement of delta(15)N of NO(3)(-). The reaction results in dilution of NO(3)(-)-N with only one reagent-derived N and the product is readily concentrated from dilute samples by reverse phase chromatography. There is systematic isotopic fractionation during the reaction, but this can be allowed for by analysing known NO(3)(-) standards along with each sample set. Sudan-1 prepared from surface water samples containing approximately 50 &mgr;g NO(3)(-)-N can be analysed by automated continuous flow isotope ratio mass spectrometry with a precision of 0.2 per thousand (one standard deviation) and the accuracy is not affected by interference from other nitrogenous species in the sample or reagents. Copyright 1999 John Wiley & Sons, Ltd.     

Proximate Composition,Bioactive Compounds,and Antioxidant Potential of Wild Halophytes Grown in Coastal Salt Marsh Habitats

Halophytes have been characterized as a potential resource for fiber, food, fodder, and bioactive compounds. Proximate composition, bioactive compounds, and antioxidant activity of five wild dominant halophytes (Arthrocnemum macrostachyum, Halocnemum strobilaceum, Limoniastrum monopetalum, Limoniastrum pruinosum, and Tamarix nilotica) naturally growing along the Nile Delta coast were assessed. The soil supporting these halophytes was sandy to sand-silty, alkaline, with low organic carbon, and relatively high CaCO₃. H. strobilaceum attained the highest moisture content, ash, crude fiber, lipids, and total soluble sugars. L. monopetalum showed the highest content of crude protein (18.00%), while T. nilotica had the highest content of total carbohydrates. The studied halophytes can be ranked according to their nutritive value as follows: H. strobilaceum > L. monopetalum > A. macrostachyum > L. pruinosum > T. nilotica. A. macrostachyum attained the highest amount of Na⁺, K⁺, Ca²⁺, and Mg²⁺. A. macrostachyum showed a high content of phenolic compounds, while H. strobilaceum was rich in tannins and saponin contents. The MeOH extract of A. macrostachyum and H. strobilaceum exhibited substantial antioxidant activity. The present results showed that the studied halophytes could be considered as candidates for forage production or used as green eco-friendly natural resources for bioactive compounds.     

Studies with 1,3-diketones: A convenient synthesis of some tetrahydro-4H-benzopyran and tetrahydroquinoline derivatives

A facile, one-step synthesis of 2-amino-5-oxo-5,6,7,8-tetrahydro-4H-benzopyran derivatives 4a-e via cyclo-addition reactions of acrylonitrile derivatives 1a-e with 1,3-cyclohexandione 2 is described. On the other hand, the reactions of 2 with the thioamides 1f-h afforded 5-oxo-5,6,7,8-tetrahydroquinoline derivatives 9a-c in good yields. The structures of the prepared compounds were established from their elemental analyses, spectroscopic data, and by their chemical transformations. © 1996 John Wiley & Sons, Inc.     

An application of the monostandard epithermal neutron activation technique for the analysis of domestic phosphate ores

The trace elements As, Co, Eu, Ga, La, Sb, Sc, Sm, U and W and the major constituents Fe and Na were determined in four domestic phosphate rocks by the monostandard epithermal neutron activation technique. Samples of 0.1 g were irradiated in the Egyptian 2 MW ERR-1 reactor under Cd cover, and the induced gamma activities measured after 6 h, 7 d and 8 w with a Hp Ge detector coupled to a computerized multichannel analyzer. Uranium has been used as a monostandard due to its relatively high resonance integral value (I₀=274.6 b) and because it is one of the elements to be determined more accurately. The present data are compared with those obtained by instrumental neutron activation analysis (INAA) method performed at Institute of Radiochemistry, Karlsruhe. The observed discrepancies do not exceed 12% in average. The present method is a practical alternative for trace element analysis.     

Heterocyclic synthesis via enaminones: Regioselective synthesis of some novel pyrazole,isoxazole, pyrimidine,pyrido[1,2‐a]benzimidazole and pyrazolo[1,5‐a]‐pyrimidine derivatives

2‐Acetylbenzothiazole ( 1 ) reacts with dimethylformamide dimethylacetal (DMF‐DMA) to afford the enaminone 2. Compound 2 reacts regioselectively with some nitrilimines 5a–d and nitrile oxides 6b–d to afford the novel pyrazole and isoxazole derivatives 11a–d and 12b–d, respectively, which react with hydrazine hydrate to give the new pyrazolo[3,4‐d]pyridazine and isoxazolo[3,4‐d]pyridazine derivatives 13a–d and 14b–d, respectively. The enaminone 2 reacts with 1H‐benzimidazole‐2‐acetonitrile ( 17 ) to afford the pyrido[1,2‐a]benzimidazole derivatives 19. Compound 2 reacts also with 5‐amino‐3‐phenylpyrazole ( 20 ) and with guanidine to afford the new pyrazolo[1,5‐a]pyrimidine and the 2‐aminopyrimidine derivatives 22 and 24, respectively. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 417–422, 1999     

DNA vaccine containing the mycobacterial hsp65 gene prevented insulitis in MLD-STZ diabetes

Background  

Our group previously demonstrated that a DNA plasmid encoding the mycobacterial 65-kDa heat shock protein (DNA-HSP65) displayed prophylactic and therapeutic effect in a mice model for tuberculosis. This protection was attributed to induction of a strong cellular immunity against HSP65. As specific immunity to HSP60 family has been detected in arthritis, multiple sclerosis and diabetes, the vaccination procedure with DNA-HSP65 could induce a cross-reactive immune response that could trigger or worsen these autoimmune diseases.     

Full ultraviolet shielding potency of highly durable cotton via self- implantation of palladium nanoclusters

Cellulose - Unique technique is currently demonstrated for preparation of ultraviolet protective cotton fabrics with full shielding effect, via self-implantation of palladium (Pd) nanoclusters....     

Wave attenuation model for dephasing and measurement of conditional times

Inelastic scattering induces dephasing in mesoscopic systems. An analysis of previous models to simulate inelastic scattering in such systems is presented and a relatively new model based on wave attenuation is introduced. The problem of Aharonov-Bohm (AB) oscillations in conductance of a mesoscopic ring is studied. We show that the conductance is symmetric under flux reversal and the visibility of AB oscillations decays to zero as a function of the incoherence parameter, signaling dephasing. Further the wave attenuation model is applied to a fundamental problem in quantum mechanics, that of the conditional (reflection/transmission) times spent in a given region of space by a quantum particle before scattering off from that region.