Chemistry Journal of Moldova

DOI: http://dx.doi.org/10.19261/cjm.2018.537   

Abstract (PDF)

Graphical Abstract: This study presents an assessment of water quality of Prut River using the Water Quality Index (WQI), calculated according to the weighted arithmetic water quality index method. The obtained results show that the water of Prut River may be classified according to WQI as good water quality of grade B for sampling points Sculeni and Cislita-Prut villages, and very poor water quality of grade D collected in the sampling point Criva village.


 

DOI: http://dx.doi.org/10.19261/cjm.2018.520   

 

Abstract (PDF)
Graphical Abstract: In this study, the chloro-substituted hydroxyxanthones were prepared by cyclodehydration of acid derivatives and substituted phenol in the presence of Eaton reagent, followed by halogenations step to electrophilic substitution of chlorine in a moderate yield. The in vitro anticancer activity study on various cell lines revealed that the chloro functional group increases the anticancer activity of the hydroxyxanthone derivatives. The molecular docking study showed that there was a binding interaction between chloro-hydroxyxanthone and the amino acid residues such as Asp810, Cys809, Ile789, His790, and Leu644 of protein tyrosine kinase receptor.


 

DOI: http://dx.doi.org/10.19261/cjm.2018.543   

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Graphical Abstract: The reaction cycle of H₂O₂ decomposition and O₂ generation catalyzed by Fenton reagent was studied using density functional theory calculations. A four-stage mechanism for the oxygen production and the Fe²⁺ regeneration in the Fenton reaction is proposed based on the obtained results. It is shown that the O-O bond cleavage of coordinated H2O2at the first step of reaction does not lead to a free HO^● radical. Instead, a highly reactive intermediate [Fe^IV(H₂O)₄(OH)₂]²⁺ with two HO^● radicals “trapped” in the complex is formed. The result of the next two reaction steps is the formation of the two HO₂^● radicals which can react on the triplet energy surface in order to produce O₂ and a H₂O₂.


 

DOI: http://dx.doi.org/10.19261/cjm.2018.544

Abstract (PDF) 

Graphical Abstract: Toxic heavy metals within a reclaimed section of the Orji mechanic village in Nigeria were determined using X-ray fluorescence and atomic adsorption spectrophotometric methods. The data were analyzed using geo-statistical techniques. Results showed that the soil was strongly contaminated by lead, and extremely contaminated by cadmium at some of the sampling points. The activities at the mechanic village in this area significantly affected the accumulation of these heavy metals and immediate soil remediation has been recommended.


 

DOI: http://dx.doi.org/10.19261/cjm.2018.525

Abstract (PDF)

Graphical Abstract: The protection performance of self-assembled layers (SALs) formed by apricot cake extract (ACE) on the surface of steel has been studied. It was revealed that the protection ability of the SALs is determined by the time of film formation on the steel surface. The maximal corrosion inhibition efficiency (about 93%) was obtained after 48 h process of film formation in the vapour phase of the apricot cake extract. The results of the electrochemical analysis revealed that the ACE modified steel showed better corrosion protection in conditions of periodic condensation of moisture.

protection in conditions of periodic condensation of moisture.

DOI: http://dx.doi.org/10.19261/cjm.2018.522   

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Graphical Abstract: The present work provides an insight into the effect of the nature of surfactant (cationic, anionic), a component of water- and oil-borne microemulsions, on the reaction rate of 1,3-dipolar cycloaddition of C,N-diphenylnitrone with acrylonitrile. The electrostatically attractive character of the cationic surfactant, would bring the reactants closer to each other; hence, a rate enhancement would ensue, particularly within the water-rich zone. Besides the fact that acrylonitrile played a dual role, as a component of the microemulsion and a dipolarphile in the cycloaddition reaction, made the work-up advantageously sound. Additionally, the increase in reagents molar ratio was found to promote higher reactivity.


 

DOI: http://dx.doi.org/10.19261/cjm.2018.516   

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Graphical Abstract: The article presents the results of studies regarding the improvement of the qualitative characteristics of blast furnace coke obtained from modified coal blend in industrial conditions of Avdeevka Coke Plant. Inorganic corundum powders are applied to modify the coal blend, namely electrocorundum (α-Al2O3) and carborundum (α-SiC). The introduction of a specific quantity (0.25 wt %) of non-clinkering additives allows the modification of the processes that occur when the coal blend is plastic, with consequent improvement in coke strength.


 

DOI: http://dx.doi.org/10.19261/cjm.2018.514 

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Graphical Abstract: The chemical composition of industrially obtained Levisticum officinale W.D.J. Koch (lovage) essential oil of Moldovan origin was analysed by means of chromatographic (GC-MS) and spectral (IR, 1H and 13C NMR) methods. The obtained results show that the main components of L. officinale essential oil are monoterpenic hydrocarbons which make up to 53.50% of the total number of components. L. officinale essential oil is also characterized by a high content of oxygenated monoterpenes (alcohols, cetones and esters), which reaches up to 33.60%. For the first time the presence of 6-butyl-cyclohepta-1,4-diene (0.56%) and 7-formyl-4-methyl-cumarine (0.15%) in lovage essential oil is reported. Antibacterial and antifungal activities of mentioned oil were evaluated in vitro on five strains of microorganisms. It was found that lovage volatile oil (L .officinale) exhibits high antibacterial and antifungal properties in the range of concentrations 0.015-0.030%.


 

DOI: http://dx.doi.org/10.19261/cjm.2018.513  

Abstract (PDF) 

Graphical Abstract: The new complexes [Ni(phen)₃][Ge(HCit)₂]•2H₂O (1), [Ni(phen)₃][Sn(HCit)₂]•3H₂O (2) (where phen is 1,10-phenanthroline, H₄Cit is citric acid) were obtained. The identity, composition, and thermal stability of the complexes were established by elemental analysis, thermogravimetry, and IR spectroscopy. According to the X-ray diffraction data, the bis(citrate)germanate / bis(citrate)stannate [Ge/Sn(HCit)₂]^2- carries out the role of the dianion while two halves of the nickel complexes with phenanthroline [Ni(Phen)₃]²⁺ are cations.


 

DOI: http://dx.doi.org/10.19261/cjm.2018.502   

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Graphical Abstract: The features of the cement clinker when rice husk is used are investigated. The dependence of the raw mixture composition on the set product burning characteristics has been analysed using the software “CLINKER”. The mixture compositions have been identified on the basis of the chalk–clay–rice husk system, with the introduction of man-made stock of 6.0–18.0 mass %. The features of the phase composition and the binder properties, by varying the rice husk content, mixture ratio and burning temperature are shown.