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Abstract: The interaction of microorganisms and their enzyme activity is one of the key indicators for a comprehensive measurement of soil health. The aim of this study was to determine significant correlations between different soil microorganisms and enzyme activities of β-glucosidase, N-acetyl-glucosaminidase, urease, arylamidase, phosphatase, acid phosphatase, alkaline phosphatase, and arylsulfatase after supplementation with standard fertilizer, spent mushroom substrate and composed fertilizer in soils from conventional–integrated, organic and biodynamic farming. Samples were grouped according to the farming system and fertilization for all seasons. The biodynamic farm was the least affected by the different fertilizations, except for standard fertilization. Standard fertilizer caused negative correlations between the actinomycetes and the arylsulfatase in organic and biodynamic farms. The same fertilization affected the actinomycetes/phosphatase relationship differently, regardless of the basic soil structure. Actinomycetes correlated positively with acid phosphatase and urease in conventional–integrated and biodynamic farms after spent mushroom substrate, respectively. Arylamidase activity in relation to total microorganisms responded to fertilization with standard fertilizer and spent mushroom substrate independently of the basic soil structure. Fertilization can influence the soil microbe/enzyme relationships in different soils. Regardless of the basic soil structure, some of these relationships could be important indicators for further studies.
Keywords: agriculture, conventional-integrated, organic, biodynamic, fertilization, soil microorganisms, soil enzyme activity
Published in DKUM: 17.04.2025; Views: 0; Downloads: 0
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Abstract: In this study, the extraction efficiency of natural deep eutectic solvents (NADES) based on choline chloride as a hydrogen bond acceptor (HBA) and five different hydrogen bond donors (HBD; lactic acid, 1,4-butanediol, 1,2-propanediol, fructose and urea) was evaluated for the first time for the isolation of valuable bioactive compounds from Achillea millefolium L. The phytochemical profiles of NADES extracts obtained after ultrasound-assisted extraction were evaluated both spectrophotometrically (total phenolic content (TPC) and antioxidant assays) and chromatographically (UHPLC-MS and HPLC-UV). The results were compared with those obtained with 80% ethanol, 80% methanol, and water. The highest TPC value was found in the lactic acid-based NADES (ChCl-LA), which correlated with the highest antioxidant activity determined by the FRAP analysis. On the other hand, the highest antiradical potential against ABTS$^{+•}$ was determined for urea-based NADES. Phenolic acids (chlorogenic acid and dicaffeoylquinic acid isomers), flavones (luteolin and apigenin), and their corresponding glucosides were determined as the dominant individual phenolic compounds in all extracts. The antibacterial and antifungal properties of the extracts obtained against four bacterial cultures and two yeasts were evaluated using two methods: the agar dilution method to obtain the minimum inhibitory concentration (MIC) and the minimum bactericidal or fungicidal concentration (MBC or MFC), and the disc diffusion method. ChCl-LA had the lowest MIC and MBC/MFC with respect to all microorganisms, with an MIC ranging from 0.05 mg mL$^{−1}$ to 0.8 mg mL$^{−1}$, while the water extract had the weakest inhibitory activity with MIC and MBC/MFC higher than 3.2 mg mL$^{−1}$.
Keywords: viskoznost, fenoli, antioksidanti, natural deep eutectic solvents (NADES), density and viscosity, yarrow, phenolic compounds, antioxidant activity, antimicrobial activity
Published in DKUM: 09.04.2025; Views: 0; Downloads: 2
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Abstract: This study is focused on different extractions (Cold Maceration (CM), Ultrasonic Extraction (UE), Soxhlet Extraction (SE) and Supercritical Fluid Extraction (SFE)) of bioactive compounds from pomegranate (Punica Granatum L.) fruit peels using methanol, ethanol, and acetone as solvents in conventional extractions and changing operating pressure (10, 15, 20, 25 MPa) in SFE, respectively. The extraction yields, total phenols (TP) and proanthocyanidins (PAC) contents, and antioxidant activity of different extracts are revealed. TP and PAC recovered by extracts ranged from 24.22 to 42.92 mg gallic acid equivalents (GAE)/g and 2.01 to 5.82 mg PAC/g, respectively. The antioxidant activity of extracts ranged from 84.70% to 94.35%. The phenolic compound identification and quantification in selective extracts was done using the LC-MS/MS method. The contents of different flavonoids and phenolic acids have been determined. SFE extract, obtained at 20 MPa, contained the highest content (11,561.84 µg/g) of analyzed total polyphenols, with predominant ellagic acid (7492.53 µg/g). For the first time, Microbial Growth Inhibition Rates (MGIRs) were determined at five different concentrations of pomegranate SFE extract against seven microorganisms. Minimal Inhibitory Concentration (MIC90) was determined as 2.7 mg/mL of SFE pomegranate peel extract in the case of five different Gram-negative and Gram-positive bacteria.
Keywords: antimicrobial activity, antioxidants, bioactive compounds, extraction, LC-MS/MS, phenolics, phytochemistry, pomegranate, Punica Granatum L., secondary metabolites
Published in DKUM: 24.03.2025; Views: 0; Downloads: 3
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Keywords: high-pressure phase equilibrium Argon, 1-butanol, 2-butanol, Peng-Robinson equation of state, Boston-Mathias alpha function
Published in DKUM: 19.03.2025; Views: 0; Downloads: 2
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Abstract: Nadarjeni učenci so po slovenski zakonodaji učenci, ki izkazujejo visoko nadpovprečne sposobnosti mišljenja ali izjemne dosežke na posameznih učnih področjih, v umetnosti ali športu. Kot taki se torej razlikujejo od učencev, ki niso bili prepoznani kot nadarjeni. Raziskave kažejo, da so nadarjeni učenci v primerjavi z normativnimi bolj zavzeti pri učenju in imajo višje učne dosežke. Za uspešno sodelovanje pri učenju pa vsi učenci potrebujejo različne vrste opore, tako s strani učiteljev kot s strani vrstnikov. Podatki so bili zbrani v okviru projekta Socialni kontekst kot dejavnik medvrstniškega nasilja, ki je bil izveden na 118 slovenskih osnovnih šolah. V naš vzorec smo vključili 6019 učencev, od tega 5030 normativnih učencev (83,57 %) in 989 nadarjenih učencev (16,43 %). Potrdili smo, da so nadarjeni učenci v primerjavi z normativnimi vrstniki učno bolj uspešni in zavzeti. Nadarjeni fantje v primerjavi z normativnimi fanti zaznavajo več vrstniške opore, nadarjena dekleta pa se od normativnih deklet v tem pogledu ne razlikujejo. Nadarjeni učenci v primerjavi z normativnimi poročajo o višji vrednosti pozitivnega vidika kakovosti odnosov z učitelji. Dodatno nadarjeni fantje v primerjavi z normativnimi fanti ter nadarjena dekleta v primerjavi z normativnimi dekleti poročajo o nižji vrednosti negativnega vidika kakovosti odnosov z učitelji. Odkrili smo, da obstaja pozitivna povezava med učno uspešnostjo nadarjenih učencev in pozitivnim vidikom kakovosti odnosa z učitelji. Prav tako pri nadarjenih dekletih obstaja negativna povezava med učno uspešnostjo in negativnim vidikom kakovosti odnosa z učitelji. Tudi učna zavzetost se pri nadarjenih učencih pozitivno povezuje s pozitivnim vidikom kakovosti odnosa z učitelji. Obstaja tudi negativna povezava učne zavzetosti z negativnim vidikom kakovosti odnosa z učitelji in pozitivna povezava učne zavzetosti z zaznano oporo vrstnikov pri nadarjenih. Naša raziskava ponuja uvid v socialne in učne vidike nadarjenih učencev v slovenskem šolskem okolju in lahko služi kot izhodiščna točka za nadaljnje raziskovanje in oblikovanje intervencij z namenom, da bi nadarjeni učenci svoj potencial dosegali v večji meri.
Keywords: nadarjeni učenci, opora vrstnikov, kakovost odnosa z učitelji, učna zavzetost, učni dosežki
Published in DKUM: 13.03.2025; Views: 0; Downloads: 15
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