Showing papers by "Minia University published in 1993"

New Sesquiterpene α-Methylene Lactones from the Egyptian Plant Jasonia candicans

Abstract: Extracts of the plant Jasonia candicans possess antimicrobial activity. ET2O/MeOH extracts were subjected to liquid chromatography, and several sesquiterpenes were isolated and identified including the known compounds confertin [1], 4,11(13)-eudesmadien-12-oic acid [2], and 11-eudesmen-4-ol [3]. Two new diol alpha-methylene lactone antimicrobial agents were identified from nmr and mass spectral data and X-ray crystallography as (4 alpha, 5 alpha, 8 beta, 10 beta)-4,10-dihydroxy-1,11(13)-guaidien-12,8-olide [4] and (4 alpha, 5 alpha, 8 beta, 10 alpha)-4,10-dihydroxyl-1,11 (13)-guaidien-12,8-olide[5], which differ in stereochemistry at the C-10 tertiary alcohol center.

Counteraction of NaCl with CaCl2 or KCl on pigment, saccharide and mineral contents in wheat

Abstract: NaCl salinity affected growth, the contents of chlorophyll, carotenoids, saccharides and some minerals (Na, K, Ca, Mg, P) in wheat (Triticum vulgaris L.) plants. Irrigation of soil with CaCl2 or KCl greatly ameliorated the adverse effects of NaCl salinity. This counteraction was associated with an increase in contents of saccharides, proteins and Ca, Mg and P which might explain their role in osmotic adjustment.

Metal chelates of some transition and non-transition metal ions with Schiff base derived from isatin with o -phenylenediamine

Abstract: New Cr(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Pb(II) chelates of the Schiff base derived from isatin witho-phenylenediamine have been synthesized and characterized on the basis of elemental analyses, electronic, IR and1H NMR spectra, and also by aid of molar conductivity and magnetic moment measurements. It has been found that the Schiff base behaves as ONNO tetradentate dibasic ligand forming chelates with 1:1 (metal:ligand) stoichiometry. Square planar environment is suggested for nickel(II) chelate. All the metal chelates show non-electrolytic behaviour.

Comparative study on the efficacy acceptability and side effects of a contraceptive pill administered by the oral and the vaginal route: an international multicenter clinical trial.

Abstract: The objective of this multicenter randomized clinical trail was to compare the efficacy acceptability and occurrence of side effects associated with the oral versus vaginal route of administration of contraceptive pills. This study started in June 1987 and data collection extended up to April 1992 at family planning clinics and research centers members of the South to South Cooperation in Reproductive Health in seven countries of the developing world. The 819 subjects were from 17 to 39 years of age had already had at least one pregnancy had had regular menstrual cycles for 3 months before were exposed to the risk of pregnancy and were not using any other method of contraception. 424 were randomly assigned to use the pills orally (which contained 250 mcg levonorgestrel and 50 mcg ethinyl estradiol) whereas 395 inserted the pills vaginally. 625 subjects completed at least 6 months of use 326 used the pills orally and 299 used the pills vaginally. 385 subjects completed 1 year of pills use 201 in the oral group and 184 in the vaginal group. The 1-year discontinuation rate per 100 subjects per year for the oral group was 34.71 +or- 2.42 while it was 36.35 +or- 2.53 for the vaginal group. This difference was not statistically significant. The only single reason of statistically significant difference for discontinuation was "desire for pregnancy" (p = 0.444). Paired value analysis of subjects completing 12 months of study showed that women in the oral group had a statistically significant increase in weight from a mean of 55.8 kg at admission to a mean of 56.9 kg at 6 months (p < 0.05) and 57.3 kg at 1 year (p = 0.05). The mean weight of the vaginal group increased from 56.52 kg to 57.22 kg (p = 0.036) at 12 months. Significantly more complaints of vaginal discharge were recorded in women using the pills by the vaginal route (p = 0.001). However only one subject discontinued the pills because of vaginal discharge.

Corrosion and passivation of tin anode in Na2CO3 solutions and the effect of halide ions

Abstract: The corrosion and passivation of tin anode in Na 2 CO 3 (001 to 10 M) was investigated using potentiodynamic and cyclic voltammetry techniques and complemented by X-ray and scanning electron microscopy The polarization curves exhibit two anodic peaks assigned to the electroformation of Sn(II) and Sn(IV) species, respectively, prior to permanent pssive region The anodic dissolution reactions are controlled by diffusion X-Ray diffraction showed that the permanent passive layer is duplex and consists of SnO and SnO 2 A multiplicity of cathodic peaks is related to the electroconduction of the anodically formed compounds Addition of Cl - , Br - or I - ions into the carbonate solutions enhances the anodic dissolution of tin to some extent depending upon the sodium carbonate concentration In the passive region, addition of the halide ions causes pitting of the halide ions causes pitting corrosion at a critical pitting potential The pitting potential decreases with increasing both the halide ion concentration and the scanning rate but increases with increasing the sodium carbonate concentration SEM examination confirms the occurance of pitting corrosion

Combating Desertification, is it always possible? The case of small Egyptian farmers

Abstract: This paper briefly presents the current state of land degradation in Egypt and then discusses the socio-economical and institutional aspects that are relevant to the problem and have bearings on possibilities of sustaining agricultural development efforts.

Sesquiterpene Glycosides from Calendula arvensis

Abstract: The extract of the aerial parts of Calendula arvensis afforded four new sesquiterpene glycosides 1-4 in addition to three known compounds. The structures of the new compounds were established by high field 1 H-nmr spectroscopy

Counteraction of NaCl with NaH2PO4 and NaNO3 on pigment, saccharide and protein contents in broad bean

Abstract: Salinity inhibited growth, and affected the contents of chlorophylls, carotenoids, saccharides, amino acids, proteins, DNA and RNA in broad bean plants. Foliar application of NaH2PO4 and NaNO3 greatly ameliorated the adverse effects of NaCI. This counteraction was associated with an increase in contents of saccharides, proteins, DNA and RNA.

Medium effects on the acid dissociation constants of some diimine heterocyclic bases

Abstract: The acid dissociation constants of the protonated form of diimine heterocyclic compounds (imidazole, 2-methylimidazole, 2,2′-bipyridyl, and 1,10-phenanthroline) were determinedpH-meterically in aqueous media containing different amounts of organic solvents, viz. amphiprotic (methanol, ethanol), dipolar aportic (DMSO), and low basic aprotic (acetonitrile) at 25±0.1 °C. It was observed that by increasing the amount of alcohol orDMSO in the aqueous medium thepKa, values of the investigated compounds decreased. On the other hand, thepKa values increased as the amount of acetonitrile in the medium was increased. These results are discussed in terms of various solvent characteristics. It is concluded that solvent effects, viz. differences in stabilization of the free base by dispersion forces and of the proton by its interaction with solvent molecules in amphiprotic or dipolar aprotic solvent-aqueous media relative to that in pure aqueous one, as well as the basicity effect of acetonitrile play a vital role in the ionisation equilibria of the investigated compounds.

Z-dependences in the reorganization of inner-shell ionized atoms

Abstract: Relative abundances of differently charged ions were calculated following inner-shell ionization. The charge distributions have been computed as a function of the atomic number. Monte Carlo method has been used to simulate the vacancy cascades in atoms of atomic number 7 ≤ Z ≤ 60. The calculations have been made by tracing successive radiative and nonradiative transitions and electron shake off. Input data have been calculated from MCDF and DFS wave functions. It has been found that the effects of electron shake off and energy forbidden Auger transitions play an essential role in the cascade development. Results are compared with experiments and some theoretical values from literature.

Synthesis through reactions of nucleophiles with acrylonitriles; part 13: a direct one-pot synthesis of thiazolopyridines

Abstract: Several new thiazolopyridines have been synthesized by a one-pot method through the ternary condensation of aldehydes with malononitrile and thioglycolic acid. Structure and reaction pathway are also reported.

MnOx-influenced bulk and surface behaviours of catalytic Al2O3

Abstract: Transitional aluminas [1], particularly the 3~-structured ones, have diverse applications in the field of heterogeneous catalysis [2]. They are utilized as potent!al catalysts in acid-base catalysed processes [2, 3], and as adequate support materials for a number of important metal and metal oxide catalysts [4]. Catalyst support materials ought to be of sufficiently high surface area, stable bulk structure, and minimal chemical reactivity towards the supported catalyst species [4]. Moreover, they should not exhibit independent catalytic activity for any substance in the process(s) for which the catalyst thereon supported is assigned [4]. Thus, supports are utilized essentially to improve the accessibility of the catalyst to the reaction, while maintaining the chemical and geometric integrities of the active sites. 3,-alumina, the present study material, is compatible with these requirements. It assumes a defective spinel structure of high thermal stability (up to 1100 °C) [1], and can be obtained in finely divided forms of favourably high surface area (>t 100 m 2 g-l) [5]. The surfaces exposed are densely hydroxylated ( 11 OH nm -2) [5], and isolated AI-OH groups (at least five different types [2]) assume varied acid-base behaviours due to the defective bulk structure [6]. These isolated OH groups act as adsorption sites for the catalyst parent species being loaded, and as anchors for the catalyst precursor species being generated during subsequent thermal treatments [4,5]. "y-alumina has, therefore, been found to facilitate synthesis of the so-called monolayer-type supported catalysts, e.g. Rh-A1203 [8]. However, the defective bulk structure of ,/-alumina is easily accessible to metal ions of favourable size and charge [9, 10]. This enhances the incursion of supported ions into the bulk during high-temperature treatments. The incursion may be restricted to a few layers underneath the surface, or may go further into the bulk depth. The former possibility usually leads to the formation of interaction compounds (e.g. aluminates), whereas the latter results in a solid solution (doping). In the solid solution, the 7-alumina bulk structure is either stabilized to withstand temperatures well above 1100 °C (the case of LaO~modified alumina [11]), or destabilized at temperatures below 1100 °C (MnOx-modified alumina [12, 13]). The bulk destabilization, which is accompanied by y---+ a-Al203 modification [13], often

New potassium ion-selective PVC membrane electrode based on alkyl thiophosphate derivatives

Abstract: Potassium ion-selective electrodes based on alkyl thiophosphate derivatives as electroactive substances have been studied. The dependence of electrode response and selectivity on the type of membrane solvent and membrane components are investigated. An electrode based on O,O-diethyl-O-(3,5,6-trichloro-2-pyridyl) thiophosphate has been shown to possess the best characteristics. The electrode displays linear response over the activity range 1–4 pK+ with a cationic slope of 58 mV/pK+ over the pH-range 5.5–7.5. The detection limit remains at −4.6 log a K + units. The values of the selectivity coefficient obtained for alkali, alkaline earth and other cations show no significant interference.

Thermal Studies of Some Dye-Adsorbent Materials

Abstract: Thermal behavior of sawdust, maize cob, and bagasse materials treated with basic dye was investigated using differential thermal analysis (DTA) and thermo-gravimetric analysis (TGA). The results showed that the thermal decomposition pat-tent of both treated and untreated material has three peaks. The first peak is endothermic while the second and the third peaks are exothermic. The peak intensities and the corresponding temperatures differ for untreated and treated materials. The effect of treatment (adsorption of basic dye) was more pronounced for sawdust and maize cob than for bagasse. The calorific values of treated sawdust and maize cob are higher than the untreated. These materials are considered new potential source for energy conversion.

Study of the electric-field effect in polyethylene by the positron annihilation technique

Abstract: The positronium formation and the reversibility behavior of the electric field from 31.75 to 588.24 kV/cm were studied in high-density polyethylene (HDPE) using the positron annihilation lifetime technique. The lifetime measurements were performed using the conventional fast-fast coincidence timing system. The observed ortho-positronium lifetime [tau][sub 3] does not show significant variation from the corresponding values measured without the electric field. On the other hand, the corresponding intensity I[sub 3] increases with increasing the electric field strength in the range from [approximately] 100 to 588.24 kV/cm. This result indicates a strong irreversible effect of the electric field. In addition, the effect of temperature on the sample stressed at 450 kV/cm was investigated. The structural changes on the heating and cooling cycles show reversible behavior. The thermal expansion coefficient has been deduced to be 7.53 [times] 10[sup [minus]3] C.