Revue des sciences chimiques

This study was conducted with the objective of determining the quantity of selected essential and nonessential metals; Co, Mg, Ca, Cu, Mn, Cr, Cd, Fe, Zn and K in the leaf and supporting soil of Khat (Catha edulis Forsk). Samples of three Khat types (Konso, Gidole and Koyra) and soils from their root zone collected from three different sites in southern Ethiopia region were analyzed by flame atomic absorption spectrometry. K in soil and Khat sample were also determined by flame atomic emission spectroscopy. Known weight of oven-dried Khat samples were wetdigested using 2 mL of (69-72%) HNO3 and 2 mL of (70%) HClO4 for 130 min at variable temperatures (120-268°C). Soil was digested by the procedure, 0.5 g samples of soil were digested with concentrated nitric acid, concentrated hydrochloric acid and hydrogen peroxide, using Kjeldahl digestion block under reflux condenser for 3 h at 300°C. Both the edible portion of Khat leaves and the soils of the study farms showed similar accumulation patterns to some extent, in their contents of the studied macro and micronutrients. Regression analysis and pearson correlation (r) results show a positive correlation Coffecient (R2) values ranging from 0.281 up to 0.991 and for pearson correlation (r) values ranging from 0.244-0.951. Although regressions based on the pooled data from the three Khat types are not adequately correlated with total metal soil levels, better fits were obtained when regression models were used for Konso Khat separately. However, no strong correlations between the leaves and other variables are evident except for Ca and Mg metal contents which have r values of 0.971 and 0.991 respectively with (p<0.01) levels. The concentrations of the metals were also compared with recommended maximum permissible limits and some international reports.

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Dielectric properties and other physical properties such as electrical conductivity (AC) and relaxation time or activation energy have been studied for two systems pure LC [V]6,6, [V]7,6, [V]8,6, [V]6,7, [V]7,7 and [V]8,7 and their doped with silver nanoparticles. The results show the increasing in real dielectric permittivity έ with increasing length terminal chain. So the real dielectric permittivity increasing with raising temperature. To compare between the values of (400) Hz and (4000) Hz we observe these values at the low frequency are larger than that in high frequency. Generally, one can see that the doping of Ag nano particles effectively reduced the permittivity of the LC materials with its large electric dipole moment. The electrical conductivity σ value for pure LC samples in general increases with increasing temperature. So we observed increasing of electrical conductivity values at high frequency. The time scale is discussed in terms of the Arrhenius plot. Generally, with increasing the temperature the time period that spends by molecules at the transition state will increase. The activation energy Ea values show the increase in the activation energy to the doped systems.

In the present research work, the solid-liquid reaction was successfully carried out in the new synthesized multisite phase-transfer catalyst, namely i.e., 1,3,5-tribenzyl-1,3,5-triethyl-1,3,5-triazinane-1,3,5-triium trichloride(MPTC), and sonication (40 kHz, 300 W) to produce the desired product namely 1-(4-nitropheny) pyrrole from pyrrole and 4-nitrochlorobenzene. The selectivity of N-arylation product was obtained under sonication and MPTC. The combination of ultrasound and MPTC resulted in better efficacy as compared to the individual operations. The apparent reaction rate is greatly enhanced and observed to obey the pseudo-first order kinetics. The kapp value increases with increasing kinetic parameters that is the amount of [MPTC], [substrate], ultrasonication, stirring speed, temperature, etc.

Four copper (II) and oxovanadium (IV) complexes of some enaminones derived from acetylacetone or trifluoroacetylacetone with methylamine have been prepared and investigated by physicochemical methods. The results have been proposed that the copper and oxovanadium complexes are in (1:2) (metal:ligand) composition and they have a square planer and square pyramidal structure, respectively. Lewis Acid-Base interaction has been studied for the prepared complexes as acceptors with pyridine as donor, and all the reactions were found as 1:1 interactions. Equilibrium consonants (Keq) for these interactions in chloroform have been measured using visible technique at different temperature. These values are within the range 6.58-16.43 L.mol-1. Thermodynamics functions ΔH, ΔG and ΔS for these interactions have also been measured. The ΔH values were within the range (-22.0 to +15.25) KJ.mol-1. The ΔG values were within the range of (−5.47 to −6.62) KJ.mol-1 while the ΔS within −55.47 to 73.38 J.mol-1.K-1.

Two imino-4-methoxyphenol thiazole derived Schiff bases, 3-(5-nitrothiazol-2-ylimino)methyl)-4-methoxyphenol (4) and 3-(5-ethyl-1,3,4-thiadiazol-2-ylimino)methyl)-4-methoxyphenol (5) were synthesized by condensing 2-amino-5-nitrothiazole (1) and 2-amino-5-ethyl-1,3,4-thiadiazole (2) with 5-hydroxy-2-methoxybenzaldehyde (3). The obtained ligands were characterized by using UV-visible, 1H, 13C-NMR and MS techniques. Data obtained from the above techniques confirmed the molecular structures of the obtained compounds. The optimized structures of the compounds were done using ACD simulation software. The synthesized compounds were tested for their antibacterial (E. coli and R. solanacearum) and antifungal (F. oxysporum and A. niger) activities. The results from these studies showed that the compounds are moderately active against the tested species of bacteria and fungi. The microbial growth inhibition by compound 4 was significantly higher than compound 5. Microbial growth inhibition activity of both the compounds was less compared with their standard drugs.

The corrosion inhibition potential of phthalic acid for mild steel in 0.1 M sulphuric acid was studied using experimental (weight loss, gasometric, FTIR and Scanning electron microscopy) and theoretical (semi empirical, Ab initio and DFT) approaches. Results obtained from weight loss measurements indicated that phthalic acid inhibited the corrosion of mild steel and recorded average and instantaneous maximum inhibition efficiencies of 55.48 and 87.34% at 303 K and at a concentration of 0.1 M respectively. Thermodynamic/adsorption considerations revealed that the adsorption of the inhibitor is exothermic, spontaneous and supported the mechanism of physical adsorption. The adsorption behaviour of the inhibitor was best described by the Langmuir adsorption model. FTIR spectra obtained from the corrosion product of mild steel in the absence and presence of the inhibitor revealed the existence of interaction between the inhibitor and the metal surface due to some shifts in the functional groups of the compound after adsorption. Scanning electron micrographs of the corroded metal (in the absence and presence of the inhibitor) revealed that phthalic acid prevented the corrosion of mild steel by forming protective coverage on the surface of the metal. Calculated quantum chemical parameters were found to be in good agreement with those reported for some good corrosion inhibitors. Although results obtained from Ab initio calculations for condensed Fukui functions were slightly at variance with those obtained from DFT calculations, considerations of Huckel charges on the atoms of the molecule, bond length, HOMO and LUMO molecular orbital plots clearly supported DFT results which indicated that the sites for nucleophilic and electrophilic attacks corresponded to atoms O(11) and C(4) respectively.

A floating liquid bridge configuration that operates in a pulsed relaxation mode in which charge (cations) and fluid injection alternatively assume forward and opposite directions in the bridge structure is reported. Cations formed at the high voltage anode are surrounded by clusters of dimethylsulphoxide (DMSO) molecules that migrate to the cathode resulting in forward fluid transport with a period of ~200 s until an equilibrium point is attained. The fluid motion then assumes the opposite direction of the current for~60 s. Charged clusters travel to the bridge surface modifying its structural properties forming a plastic layer with an ~85 KPa stiffness.

Paracetamol and piroxicam are non-steroidal anti-inflammatory drugs (NSAIDs), widely used in pain and inflammatory diseases. The present study aimed to evaluate the impact of biofield treatment on spectral properties of paracetamol and piroxicam. The study was performed in two groups (control and treatment) of each drug. The control groups remained as untreated, and biofield treatment was given to treatment groups. Subsequently, spectral properties of both drugs before and after biofield treatment were characterized using FT-IR and UV-Vis spectroscopic techniques. FT-IR data of paracetamol showed N-H amide II bending peak in biofield treated paracetamol, which was shifted to lower wavenumber (1565 to 1555 cm-1) as compared to control. Further, the intensity of vibrational peaks in the range of 1171-965 cm-1 (C-O and C-N stretching) were increased in treated sample of paracetamol as compared to control. Similarly, the FT-IR data of piroxicam (treated) showed increased intensity of vibrational peaks at 1628 (amide C=O stretching), 1576-1560 cm-1 (C=C stretching) with respect to control peaks. Furthermore, vibrational peak of C=N stretching (1467 cm-1) was observed in biofield treated piroxicam. This peak was not observed in control sample, possibly due to its low intensity. Based on FT-IR data, it is speculated that bond length and dipole moment of some bonds like N-H (amide), C-O, and C-N in paracetamol and C=O (amide), C=N, and C=C in piroxicam might be changed due to biofield treatment. The UV spectrum of biofield treated paracetamol showed the shifting in wavelength of UV absorption as 243→248.2 nm and 200→203.4 nm as compared to control. Likely, the lambda max (λmax) of treated piroxicam was also shifted as 328 →345.6 nm, 241→252.2 nm, and 205.2→203.2 nm as compared to control. Overall results showed an impact of biofield treatment on the spectral properties of paracetamol and piroxicam.

The kinetics for dichlorocyclopropanation of N-vinylimidazole with an excess of chloroform has been studied under multi-site phase-transfer catalyst and ultrasound irradiation conditions using aqueous sodium hydroxide as the base. The reaction was carried out at 40°C and a pseudo-first order rate is used to describe the reaction rate at high alkaline concentration (>30 wt.%). Kinetics of the reaction including the effects of the reaction conditions on the conversion of N-vinylimidazole was investigated. A rational explanation was made for a peculiar phenomenon that the conversion of N-vinylimidazole was increased and then decreased with an increase in the amount of sodium hydroxide and the kapp value increases with increasing other kinetic parameters that is the amount of multi-site phase-transfer catalyst, viz., N,N’-dihexyl-4,4’-bipyridinium dibromide, concentration of substrate, ultrasonication, stirring speed, temperature, etc.