Studia Universitatis Moldaviae. Stiinte reale si ale naturii

8-16

Authors: Iurie BACALOV, Adriana DRUŢA, Alina TROFIM

This research complements experimental data on the use of aqueous extract of Calothrix marchica, which improves the general condition of the body by balancing haematological indices in experimental diabetes. The advantage of using aqueous extract of Calothrix marchica in experimental diabetes is the accessibility, mild action and lack of side effects when adhering to the recommended doses. The administration of the investigated aqueous extract reduced blood glucose,¬ stimulated insulin secretion, and influenced leukocyte counts in acute and chronic complications of alloxan diabetes.

23-26

Authors: Inga DELEU

This paper describes the importance of testing the level of haemoglobin in relation to the arterial oxygen saturation in the body of swimmers, both at rest and after a swimming effort. After testing at rest, the haemoglobin level is below the norm, and after a swimming effort, there is a non-essential increase in this index. The arterial oxygen saturation at rest presents values within the limits of the norm, and after an effort, an increase of SpO2 values is also observed. Therefore, as a result, we can observe a correlation between the estimated respiratory parameters.

33-38

Authors: Rodion DOMENCO, Maria DUCA, Ilie BOIAN, Ion BURCOVSCHI

Sunflower is one of the most important oil plants grown in the world and the main oilseed plant on the territory of the Republic of Moldova, being a crop with a wide spectrum of use in the food and industrial sectors. In the Republic of Moldova the areas sown with sunflowers increased continuously during the period 2010-2019, starting with 252 thousand ha in 2010 and up to 359 thousand ha in 2019. The overall yield of sunflower seeds in 2019 increased by 112% compared to 2010 and constituted 811,000 tonnes. Compared to 2018, the global sunflower yield increased by 2.8%, and compared to 2017 by only 0.8%. We can assume a trend of stabilizing global production around 800 thou-sand tonnes. Regionally, the average yield is usually higher in the Northern region due to more favourable climatic and relief conditions. But in some years, depending on the distribution of precipitation, a higher average yield per hectare would be achieved in the South. For example, the average yield in the Northern area of the republic was 18.6 q/ha, in the Centre area – 19.2 q/ha, and in the South area – 21.7 q/ha in 2016.

49-53

Authors: Ion TIMUȘ

The results obtained in the study of the action of nanoparticles supplemented in the lyoprotective medium on the viability of the fungal strain P. funiculosum CNMN FD 11 demonstrated that nanoparticles act differently on the viability of microorganisms after lyophilization. Thus, ZnO nanoparticles supplemented in the lyoprotective medium in low con¬centrations 0.1-0.5 mg / l act positively or neutrally, and in high concentrations (5-10mg / l) negatively, but the nanoparticles of Fe2O3 and Fe2ZnO4 in a concentration of 5mg / l can stimulate the viability of the strain after lyophilization. It has also been established that the method of freezing (gradual or rapid) does not significantly influence the viability of the culture after lyophilization.

60-63

Authors: Elena PELEAH, Victor MELNIC, Ion DRAGALIN

A comparative study of various wild Mentha spicata L. ecotypes from Moldova and from other geographical areas was carried out. According to the morphological features, the ecotypes were not different and were in line with the botanical description of study species. To identify potential opportunities for mint ecotypes, the vegetation features, yield of oil and essential oil composition was studied. It was revealed that in the same area both analogous and different chemotypes grow, which resulted from free pollination while maintaining the morphology of species.

69-73

Authors: Ирина КОЛОМИЕЦ, Игорь ДРАГУЦАН

The distribution of absorbed solar energy was studied both through mathematical modelling and experientially on plants of the species Papaver rhoeas L., Borago officinalis L., Oenothera biennis L. in the flowering phase. It was found that the radiation energy and heat transfer energy for the corolla model of red, blue and yellow colours are constant, and the evaporation energy of corolla varies and depends on the absorption energy of the corolla, so that the higher the absorption energy, the greater the evaporation energy. The energy of evaporation increases in the following order: corollas with blue coloration

79-82

Authors: Victor ȚÎȚEI, Natalia CÎRLIG, Ana GUȚU

This article describes some peculiarities of the growth and development of the 'Vital' cultivar of Silphium perfoliatum L. and the advantages of its cultivation under the climatic conditions of the Republic of Moldova. It has been found that cup plant, in the second and the following years, has a growing season of 197-234 days, blooms and bears fruit, producing viable seeds. The flowering stage is long and staggered, thus, cup plant is a good source of pollen and nectar for bees and other insects. The aerial phytomass has high economic value as fodder for animals and as substrate for the production of renewable energy.

87-90

Authors: Serghei CORCIMARU, Vasile TODIRAȘ, Svetlana PRISACARI, Angela LUNGU, Leonid ONOFRAȘ, Tatiana GUȚUL

The purpose of this work was to study the influence of nanoscale zerovalent iron (NZVI) on the growth of soya in soil contaminated with persistent organic pollutants (POPs). Soil treatment with 25 mg/kg of NZVI resulted in soya growth stimulation in different sub-variants with and without preliminary seed bacterization with Rhizobium japonicum RD2: the root length and the dry mass of the aerial part of plants were respectively 22.9-28.8% and 21.7-31.5% higher than in the control variant. Also, according to the latter parameter, soil treatment with NZVI in combination with seed bacterisation produced the results that were statistically higher than in the sub-variants with NZVI treatment only (+8.0%), and with seed bacterisation only (+12.3%). NZVI stimulated the rhizobial symbiosis by increasing the number of root nodules by 2.7-14.0 times. As a result, NZVI, soya and symbiotrophic bacteria of the genus Rhizobium were found to possess a promising potential for nanobioremediation of soils contaminated with POPs.

101-112

Authors: Diana CEBOTARI, Mohamed HAOUAS, Sébastien FLOQUET, and Aurelian GULEA

Six new bis-thiosemicarbazones ligands were synthesized with rigid or flexible organic chemical links between the two thiosemicarbazones moieties. Such ligands have been designed for the synthesis of polymetallic coordination complexes. They were synthesised by the condensation reaction between aldehydes and substituted thiosemicarbazides in alcohol, using acetic acid as a catalyst. To determine the composition, the products were characterised by 1H, 13C and 15 N nuclear magnetic resonance, mass spectrometry and elemental analysis.

119-126

Authors: Maria BÎRCĂ, Aliona COTOVAIA, Victor ȚAPCOV, Olga GARBUZ, Valeriu CRUDU, Aurelian GULEA

The paper reveals the synthesis and investigation of antituberculosis properties and antioxidant activity of 13 new coordination compounds of Cr3 +, Mn2 +, Fe3 +, Co3 +, Ni2 +, Cu2 +, Zn2 + with isonicotinoyl hydrazone of 2-hydroxy-3-methoxybenzaldehyde (H2L). The ligand (H2L) was obtained by condensing isonicotinic hydrazide with 2-hydroxy-3-methoxybenzaldehyde. The structure of the ligand was determined by single crystal X-ray diffraction. The considered compounds display high antituberculosis and antioxidant activities.

140-143

Authors: Andrei NEGUȚA, Elena NEGUȚA

This paper relates a synthesis method of 8-methyldecan-2-yl propanoate racemate from commercially available chemicals. It implies cross-coupling of 2-bromobutane with Grignard reagent formed of hexamethylene chlorohydrin and magnesium. The obtained 7-methylnonan-1-ol is oxidized to aldehyde with pyridinium chlorochromate and coupled with the Grignard reagent obtained from methyl iodide and magnesium. The resulted alcohol was esterified with propanoic anhydride. The racemate of 8-methyldecan-2-yl propanoate is applied as a sex pheromone of the western corn root¬worm.

150-156

Authors: Tatiana ISAC-GUŢUL, Elena TUTOVAN

Sulfamides (SN) are a class of broad-spectrum synthetic bacteriostatic antibiotics, whose structure includes the sulphonamide functional group. Several SN derivatives are used as antiprozoal agents and herbicides, as antifungals and their frequent use ultimately leads to a negative impact on the environment. The paper deals with the kinetic regularities and degradation of phthalazole (FL) and acetazolamide (AC) as examples of sulphonamides in the SN-h and SN-H2O2-h¬ systems. The high-pressure mercury-deuterium lamp “ДРТ–1000” was used as a source of UV radiation. It was determined that the degree of oxidation of the sulphonamides at the variation of the concentrations from 1∙10-4 mol/L to 3,75∙10-4 mol/L is between 60-78%. For a more complete oxidation H2O2was added in the system as an oxidant with a concentration range 510-4 - 510-3 mol/L. As the oxidant concentration increased, the degradation degree of substrate was between 69-88%. The experimental data allowed us to determine the reaction rate as a function of the initial concentrations of the used substances. The principal active particles generated in this system are detected and the mechanism scheme of the oxidation processes is proposed.

167-176

Authors: Veronica PORUBIN-SCHIMBĂTOR, Maria GONŢA, Larisa MOCANU

To prevent surfactant contamination of water and soil, the decrease of CTAB cationic surfactant in model systems has been studied by using photodegradation under UV/TiO2/ H2O2 and UV/Fe2+/H2O2 (photo-Fenton) conditions. In both processes, the factors influencing the effectiveness of photodegradation were evaluated. The residual concentration of the cationic surfactant was determined by UV/VIS spectrophotometry using methylene blue as a colouring agent and extraction. The research results showed that the concentration of the CTAB surfactant could be significantly reduced by using both UV/TiO2/H2O2 processes and UV/Fe2+/H2O2 processes with a degree of mineralization and degradation of about 50%. In both processes the dependence of the photodegradation efficiency of the surfactant on the physico-chemical parameters was observed: TiO2 concentration, Fe(II) and H2O2 concentrations, pH, time and wavelength. The homogeneous/heterogeneous photocatalytic oxidation reaction rates and the degree of mineralization were determined according to different physico-chemical parameters. It was found that the optimal pH for the oxidation of CTAB with photo-Fenton reagent is 2.5, and for the UV/TiO2/H2O2 system – 4.0. It is also confirmed that the UV/Fe2+/H2O2 process (photo-Fenton) was more efficient in the photodegradation of the CTAB surfactant than that of the UV/TiO2/ H2O2 process.