Classical and advanced chemical sciences
A simple one-pot four-component synthesis of pyrano[2,3-c]pyrazoles has been achieved by the condensation of aldehydes, malononitrile, ethyl acetoacetate and hydrazine hydrate using lemon peel powder as a natural catalyst in ethanol under reflux condition. The advantages of this reaction are less reaction time, high yield, easy availability of the catalyst and green nature of the protocol
Keywords: Pyranopyrazoles; lemon peel powder; one-pot synthesis; natural catalyst
Physical-chemical characteristics and activity of the Pd-MnOx-catalyst, deposited on cordierite carrier, was studied in the CO oxidation reaction. The results obtained on the catalyst Pd-MnOx-/Al–Si showed the similar activity in the CO oxidation reaction as in the case of the Pd-MnOx/CaO.2Al2O3 catalyst.
Keywords: CO oxidation; manganese oxides; alumosilicate blocks, promoting, active surface.
Materials and environmental chemistry
In the present work, samples of water and fish were collected from the river Nile at El- Qanater El- Khyria as non-polluted site and from downstream of El-Rahawy drain (El-Qatta) as a polluted drain during different seasons of 2016. The concentration of metals (Fe, Zn, Cu, Pb, Mn and Cd) in water and their accumulations in fish muscles were measured. Electrophoresis pattern of Oreochromis niloticus including protein pattern, calcium pattern and β-esterase have been determined. In the present study, results revealed increased concentrations of studied metals in water and fish samples mainly during the winter season. The values of Fe, Cu, Pb, Mn, Zn and Cd were higher than the permissible limits in water, while Fe, Pb and Zn exceeded the permissible limits in fish muscles, especially those of El-Qatta station. Results of electrophoretic protein pattern showed similarities in arrangement of the bands in liver and muscles tissues in fishes taken from both locations (A and B). The cumulative risk impacts have been discussed.
Keywords: use the Keywords style for the list of keywords, separating with a comma each items
Atomic absorption spectroscopy has been used to analyses and assesses the heavy metal content in water of the Llapi river, Kosovo. In this study, the assessment of heavy metals in water was realized in the summer period. Statistical studies have been carried out by calculating basic statistical parameters, anomalies (extremes and outliers) and correlation coefficients between different pairs of variables. The concentration of Cr, Ni, Zn, Cu and Fe in all sample stations were found to be under WHO recommended norms. But the concentration of Cd and Pb in all sample stations and concentrations of Mn at several stations were found to be above WHO recommended norms originated from mineral sources (ores) in this area. The statistical regression analysis has been found a highly significant positive relationship of Cd with Ni, Mn, Fe and Pb originated mainly of sulphide ores in this area.
Keywords: Water; heavy metals; atomic absorption spectroscopy; correlation coefficients; Llapi river
This work aims at studying the electrochemical behaviour of metals like 18 carat gold in presence of Simulated Ringer’s Solution and Lactated Ringer’s Solution in presence of 100 ppm of NaCl and also 100 ppm of glucose are used to simulate the body fluids. The behaviour of the metal was monitored by polarization study and electrochemical impedance spectroscopy (EIS). All the experiments were carried out at a constant temperature of 37 °C. From these studies, it was concluded that the avoid of excess of NaCl and also glucose in both Ringer solutions in medicinal uses.
Keywords: 18 Carat gold; electrochemical studies; Ringer solutions; corrosion
Theoretical and computational chemistry
Basic parameters of molecular structures of Al2Ti3 and Al2V3 metal clusters (bond lengths, bond angles, and torsion (dihedral) angles), have been calculated using DFT method at the OPBE/QZVP level. It has been shown that the Al2Ti3 cluster may exist in 14 modifications and Al2V3 in 11 ones, differing noticeably in their total energy. Besides, the molecular structures of these metal clusters differ significantly in terms of geometric parameters as well as in external form. Moreover, the most energetically stable modifications of Al2Ti3 and Al2V3 clusters differ each other considerably in geometric form also.
Keywords: Metal cluster. aluminum; titanium; vanadium; molecular structure; DFT method