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  • Author or Editor: M. A. Zayed x
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Labour and greenhouse experiments were conducted to study the effect of magnetic field treated water on germination, growth and physiological and biochemical changes in tomato (Lycopersicon esculentum L.), wheat (Triticum aestivum L.) and pea (Pisum sativum L.). The results indicated that magnetic field treated water increased seed germination percentage, seed germination value and seedling vigour index. Magnetic field treated water increased also plant height, leaf area per plant, specific leaf area (SLA), leaf relative water content (LRWC), whereas the leaf water deficit (LWD) values were decreased. Biochemical analysis of the plant leaves irrigated by magnetic field treated water clarified changes in the photosynthetic pigments, UV-absorbing substances (UVAS), activities of peroxidase (POX) and polyphenol oxidase (PPO) enzymes, carbohydrates, phenolics and mineral ion contents. The latter changes are associated with the modifications in the membrane integrity of the plant leaves and the concentrations of some endogenous hormones in the plant shoots.

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Plant litter of Zygophyllum was collected in the desert region (Suez desert region and Mediterranean coastal region). The litter was subdivided into leaves, stems, flowers and fruits. The mean total litter production was 173.3 g per shrub per year in the Mediterranean region and 138.3 g per shrub per year in the Suez region. Leaves constitute generally the largest litter category composing 70-76% of the total litter. The nitrogen and phosphorus concentration of fresh leaves was found to be twofold more than that of nitrogen and phosphorus found in the litter.

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The effect of different concentration of NaCl on growth, mineral ions and organic solutes content of Artemisia monosperma were investigated. Experimental measurements were made after 70 days of growth in vessels containing Hoagland nutrient solution under controlled climatic conditions. Increased salt stress decreased dry mass, length of shoot and root as well. At the same time, the osmotic potential of NaCl had a great effect on the shoot/root ratio. The root initials also increased and the number of root initials decreased by increasing NaCl concentrations up to 0.4 MPa. It was also observed that proline, saccharide, and soluble protein contents increased in the shoot sap of the investigated plant. Glycolic, fumaric, tartaric, and succinic acid were clearly affected by increasing salinity in the nutrient solution, whereas oxalic and citric acids were significantly increased up 8.5 and 12 times of the control samples.

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Atriplex leucoclada (Chenopodiaceae) is a shrub growing in many different habitats in sand dunes. The sand dune system is characterised by its small-scale heterogeneity. Atriplex occurs in different habitats varying from sand to playas where has high accumulation of salts. Ion accumulation and water relations of Atriplex leucoclada growing in different habitats were compared. Atriplex leucoclada showed a genetic fixed ion pattern independently of soil type.

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In deserts, biological processes decrease at the end of the vegetation period by lack of soil moisture and increasing heat. Important processes for plant nutrient uptake are negatively affected like N fixation, litter decomposition and denitrification. Desert plants must therefore adapt their mineral household towards best use of available nutrients and storage of minerals in perennial organs. Here we studied this pattern by experiments of the effect of nitrogen nutrition on mineral concentration and plant growth of Retama raetam (Forssk.) Webb. Berth for two years in sand culture. In summary, the mineral household of R raetam seems to be well adapted to unfavourable desert habitat independent from the N source and N level.

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Abstract

Four novel azo compounds were synthesized: o-phenylazo-(C14H13N3O2) (I), p-bromo-o-phenylazo-(C14H13BrN3O2) (II), p-methoxy-o-phenylazo-(C15H16N3O3) (III), and p-nitro-o-phenylazo-p-acetamidophenol (C14H13N4O4) (IV). These compounds were carefully investigated using elemental analyses, IR, and thermal analyses (TA) in comparison with electron ionization (EI) mass spectral (MS) fragmentation at 70 eV. Semi-empirical MO calculation, PM3 procedure, has been carried out on the four azo dyes (I–IV), both as neutral molecules and the corresponding positively charged molecular ions. These included molecular geometries (bond length, bond order, and charge distribution, heats of formation, and ionization energies). The mass spectral fragmentation pathways and thermal decomposition mechanisms were reported and interpreted on the basis of molecular orbital (MO) calculations. They are found to be highly correlated to each other. Also, the Hammett’s effects of p-methoxy, p-bromo, and p-nitro-substituents of phenyl azo groups on the thermal stability of these dyes (I–IV) are studied by experimental (TA and MS) in comparison with MO calculations, and the data obtained are discussed. This research aimed chiefly to throw more light on the structures of the four prepared azo derivatives of acetoamidophenol (p-cetamol). The data refering to the thermal stability of these dyes can be used in industry for effective dyeing purposes under different thermal conditions.

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Summary  

This paper describes the use of the mass spectrometry (MS), thermal analyses (TA) and other physico-chemical methods to investigate the structure of two newly synthesized phenolic-iodine derivative polymeric products. These two products are formed as a result of redox-interaction of adrenaline hydrogen tartrate (AHT, I) with iodate (IO- 3) and periodate (IO- 4). The characterization of the two products were achieved satisfactorily by using the above tools and their proposed general formulae, were found to be C52H67O36N4I (AHT- IO- 3, II) and C26H34O18N2I2(AHT- IO- 4, III). The fragmentation behavior of the main compound (AHT) in MS and TA (TG and DTA) techniques was investigated and compared. The results obtained were used to explain the fragmentation of the products AHT- IO- 3and AHT- IO- 4in mass spectrometry and thermal analyses techniques. The stabilities of different fragments were discussed. The results indicate that the two techniques are supporting each other in which the mass spectrometry provides the structural information in gas phase while the thermal analyses provides the quantitative fragmentation in the solid-state.

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Abstract  

The 5,7-dichloro, 5,7-dibromo, 5,7-diiodo and 5,6-dinitro derivatives of oxine (ligandsL 1,−L 4) were used to prepare uranyl chelates (A 1A 4). Thermal analysis (DTA) and mass spectroscopic studies were performed. The stoichiometries of the chelates were determined by elemental analysis, molecular weight determination applying an α-spectroscopic liquid scintillation counter and mass spectral measurements. The uranyl∶ligand ratios were found to be 1∶1 for A1, 1∶3 for A2, 1∶2 (monohydrate) for A3, and 1∶2 forA 4. The correlation between the thermal analysis and mass spectra was examined. The activation energy required for each step of thermal degradation of the ligands and chelates was calculated. The natures of most of the molecular ions obtained in the mass spectra were also explained.

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Abstract

Ibuprofen (C15H18O2) is an anti-inflammatory drug. It is important to investigate its structure to know the active groups and weak bond responsible for its medical activity. Consequently in the present study, ibuprofen was investigated by mass spectrometry (MS) and thermal analyses (TAs) (TG/DTG and DTA), and confirmed by semi-empirical molecular orbital (MO) calculation using PM3 procedure, on the neutral and positively charged forms of the drug. These calculations included bond order, bond length, and bond strain, and charge distribution, heat of formation, and ionization energy. The mass spectra and thermal analysis fragmentation pathways were proposed and compared to each other to select the most suitable scheme representing the correct fragmentation pathway of the drug in both techniques. From the electron ionization (EI) mass spectra, the primary cleavage site of the charged molecule is because of the rupture of COOH group (the lowest bond order) followed by propyl group loss. The TAs of the drug revealed high response of the drug to the temperature variation with very fast rate. It decomposed in several sequential steps in the temperature range 25–360 °C. The initial thermal decomposition is similar to that obtained by MS fragmentation of the first rupture (COOH), then subsequent one of propyl loss, and finally of ethylene loss. These mass losses appear as endothermic peaks required energy values of −214.83, −895.95, and −211.10 J g−1, respectively. The order of these losses is also related to the values of the MO calculation parameters. Therefore, the comparison between MS and TA helps in the selection of the proper pathway representing the decomposition of this drug to give its metabolites in in vivo system. This comparison is also successfully confirmed by MO calculations.

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