Facultatea de Chimie şi Tehnologie Chimică / Faculty of Chemistry and Chemical Technology
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Item Dynamics of the self-purification processes in the waters of the Dniester river during the years 2015-2024 (Dubasari - Vadul lui Voda section) [Articol](2025) Cisteacov, Maxim; Duca, Gheorghe; Blonschi, Vladislav; Gladchi, Viorica; Lis, Angela; Bunduchi, ElenaIt has been evaluated the dynamics of the self-purification processes of the Dniester River waters in the section from Dubasari to Vadul lui Voda based on the analysis of the parameters: biochemical oxygen demand (BOD5), chemical oxygen demand (CODCr), thiol content, and the inhibition capacity of the waters in carrying out chemical self-purification processes through free radicals (ΣkiSi). According to the BOD5 values, the Dniester waters belong to quality classes II and I, and according to the CODCr parameter, they fall into quality classes II and III. The thiol content is typical of fresh waters (10⁻6 M), and they are of natural origin. The inhibition capacity classifies the river's waters as slightly and moderately polluted. Along the river, were observed a decrease in biological self-purification processes and an increase in the intensity of free radical processes in the Criuleni area, indicating an additional inflow of reducing compounds into the Dniester waters from its tributary, the Raut River. Additionally, a tendency was noted for the aquatic environment quality restoration in the Vadul lui Voda area.Item Rolul cobalaminei în procesele de autopurificare radicalică în mediul acvatic [Articol](CEP USM, 2024) Lis, Angela; Gladchi, Viorica; Blonschi, Vladislav; Cisteacov, Maxim; Bunduchi, ElenaThe main purpose of this research is to study the role of Cyanocobalamin (CNCbl) in aquatic ecosystems. The spectrophotometric method was used to determine the inhibition capacity and the concentration of OH radicals using PNDMA traps. As a result, it was found that, on the one hand, CNCbl is a reducing substance and leads to the consumption of oxidative equivalents, resulting in its oxidation. High inhibition capacity values and low OH radical values confirmed this. On the other hand, under irradiation, CNCbl can also act as a sensitizer. It actively absorbs photons in the UV and visible range, transitions to an excited state, and then transfers the electronic excitation energy to dissolved oxygen in water, forming active species such as singlet oxygen and superoxide radical anion. In the presence of protons, the superoxide radical anion is reduced to hydrogen peroxide, which generates OH radicals upon irradiation. From the obtained results, it can be seen that under the conditions of natural aquatic systems, CNCbl will not disturb the processes of radical self-purification.Item Stabilirea impactului poluării cu vitamina B6 asupra capacității de autopurificare a sistemelor acvatice naturale (lacuri) [Articol](CEP USM, 2024) Bunduchi, Elena; Gladchi, Viorica; Cisteacov, Maxim; Lis, Angela; Blonschi, Vladislav; Duca, GheorgheIn the framework of this research, it was aimed to establish which concentrations of vitamin B6 can be considered triggers of the pollution phenomenon in natural aquatic systems of the lentic type, such as the Danceni and Ghidighici lakes. The modeling was done on microcosm type systems. The pollution and auopurification processes were monitored according to the quality indicators for natural waters: pH, permanganateometric oxidizability (CCOMn), degree of saturation with dissolved oxygen (OD, mgO2/L) and inhibition capacity (Σki[Si], s-1). Research shows that natural waters can become vulnerable to vitamin B6 pollution in concentrations of the order of ≤ 0.5·10-4 M, because self-purification processes fail to eliminate the pollution caused by these concentrations, only slightly attenuating it. The consumption of active forms of oxygen, OH radicals, important particles of the chemical self-purification process of natural waters, highlight even more the negative impact of the pollution of aquatic systems with vitamin B6.Item Transformări fotochimice ale izoniazidei în mediul acvatic [Articol](CEP USM, 2024) Lis, Angela; Gladchi, Viorica; Bunduchi, ElenaThe main purpose of this research is to study the photochemical transformations of isoniazid (InH) and its influence on aquatic ecosystems. The spectrophotometric method was used to determine the kinetic parameters of the InH photodegradation. as a result of the research, it was found that InH undergoes direct and induced non-catalytic and catalytic photolysis. Based on the half-life parameter, it was found that InH undergoes photodegradation most quickly in non-catalytic indirect photolysis, then in catalytic, and fnally very slowly in direct photolysis. If the results obtained on the model systems are transferred to natural aquatic systems, it can be highlighted that the InH half-life will be 7-8 min. as a result, it was established that InH has negative effects on aquatic ecosystems. It consumes oxidative particles, especially OH radicals, which maintain aquatic systems’ self-purifcation capacity. It also binds Cu(II) ions in complexes with lesser catalytic activity.Item Content of harmful and potentially harmful substances in conventional cigarette smoke and in tobacco heating system TSH 2.2. Comparison of the scientific results of independent research and Philip Morris International [Articol](CEP USM, 2024) Gonța, Maria; Gladchi, Viorica; Bunduchi, ElenaIn this paper, the content of harmful and potentially harmful constituents (HPHCs) in conventional cigarette smoke and in the Tobacco Heating system 2.2 (THs 2.2) product, developed by Philip Morris International (PMI) and marketed under the brand name IQOs (I Quit Ordinary smoking), as well as for conventional 3R4F cigarettes, was examined using statistical data obtained from studies of scientifc papers published between 2015 and 2022. Based on the analysis of the results presented by independent and industry-sponsored studies, it was found that the harmful and potentially harmful constituents (HPHC) are not entirely eliminated from the HTP aerosol, so these products are still not without risks for the population. The data obtained for all analyzed chemicals, with the exception of the substance with order number 30, n-nitrosoanabasine, support the theory put out in this study, according to at least one group or multiple groups of independent experts. In other words, in each individual case, at least one group of independent experts attests that the information provided by the company’s experts about the concentrations of the analyzed compounds (at least for the maximum values obtained) in the aerosol stream emitted by an IQOs device is not diminished.Item Evaluarea potențialului antioxidant al unor ingrediente cosmetice cu acțiune de hidratare [Articol](CEP USM, 2024) Bunduchi, Elena; Gladchi, VioricaThe paper presents the results of the study on the involvement of four amino acids (glycine, leucine, alanine and phenylalanine) in the oxidation processes activated by solar radiation, namely uV radiation. Research was carried out to determine whether these amino acids could perform, in addition to the cosmetic care action, the protection, prevention and combating of oxidation processes activated by solar radiation, namely, those with the participation of OH radicals. The study used the method of competing acceptors and a radiation source that simulates the solar spectrum at the earth’s surface. It has been established that amino acids participate in the regeneration processes of the active form of oxygen, OH radicals, so they cannot be recommended as multi-action ingredients in cosmetic formulas.