1. Sustainable extraction of hemp seed and formulation extracts into organogels with analytical profiling of fatty acidssubcritical fluids in food processingSara Karlovšek, Taja Žitek Makoter, Teo Makoter, Željko Knez, Maša Knez Marevci, 2025, original scientific article Abstract: Sustainable extraction methods for natural extracts are crucial for mitigating environmental impact. Strategies that focus on waste reduction and resource efficiency contribute to long-term conservation. Hemp seeds, which were previously treated as waste product, are now valued for their nutrition and functional properties. This study investigated sustainable extraction methods for obtaining natural extracts from hemp seeds, with a focus on reducing environmental impact through efficient resource utilization and waste reduction. The extraction methods compared included supercritical fluid extraction (SFE), Soxhlet extraction (SOX), ultrasound-assisted extraction (UAE), cold maceration (CM), and cold pressing (CP). The contents of antioxidants, total phenols, and fatty acids in the extracts were analyzed via gas chromatography–mass spectrometry (GC–MS). The extracts were subsequently formulated into organogels to evaluate the stability of the fatty acids. The results showed that SFE and CP were the most efficient and environmentally friendly methods, with SFE allowing complete separation of the solvent from the extract. CP was also found to be effective and environmentally friendly. The study confirmed that formulating extracts in organogels effectively inhibited fatty acid oxidation, although a reduction in fatty acid content was observed during gel production. Overall, the formulation of extracts in organogels increased their stability, especially in preventing fatty acid degradation.
Keywords: supercritical fluid extraction, ultrasound extraction, cold pressing method, fatty acids, stability of formulations
Published in DKUM: 15.10.2025; Views: 0; Downloads: 3
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2. Controllability-oriented method to improve small-signal response of virtual synchronous generatorsAntonija Šumiga, Boštjan Polajžer, Jožef Ritonja, Peter Kitak, 2025, original scientific article Abstract: This paper presents a method for optimizing the inertia constants and damping coefficients of interconnected virtual synchronous generators (VSGs) using a genetic algorithm. The goal of optimization is to find a balance between minimizing the rate of change of frequency (RoCoF) and enhancing controllability. Five controllability-based metrics are tested: the minimum eigenvalue, the sum of the two smallest eigenvalues, the maximum eigenvalue, the trace, and the determinant of the controllability Gramian matrix. The approach includes the oscillatory modes’ damping ratio constraints to ensure the small-signal stability of the entire system. The results of optimization on the IEEE 9-bus system with three VSGs show that the proposed method improves controllability, reduces RoCoF, and maintains the desired oscillation damping. The proposed approach was tested through time-domain simulations.
Keywords: virtual synchronous generator, inertia constant, damping coefficient, small-signal stability, multi-objective optimization, genetic algorithm
Published in DKUM: 12.08.2025; Views: 0; Downloads: 11
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3. The numerical analysis of flame stability in case of premixed hydrogen-air combustionMarc Jaeger, Matjaž Hriberšek, Niko Samec, Yang Guo, Xuebin Wang, Filip Kokalj, 2025, original scientific article Abstract: This study addresses the urgent need for decarbonization of heating sector, focusing on the potential of hydrogen-air combustion in gas condensing boilers. In the field of gas condensing boilers, groups of holes or slits can be used in perforated burner surfaces, providing a possible solution to the challenge of hydrogen air combustion. Real burners are always adjacent to an area with non-existent combustion, which can lead to a disturbed flame pattern. For this reason, a comparison between single-slit and multi-slit perforated flame holders with a significantly reduced structure temperature with a hydrogen-air premix is carried out as part of this study. Using Ansys Fluent, a 2D simulation approach is employed to analyze laminar flame stability behind a perforated flame holder. Inlet conditions consider fully premixed and homogenous distributed mixtures as well as nonhomogeneous premixed mixtures, with variations in pressure, velocity, and mixing degree. The model examines various slit-burner configurations and flashback behaviors based on an actual geometric shape used in a gas heating device. It has been found that with finite multi-slit burners, the bulk flow rates at the critical flashback point are 30–50% higher compared to infinitely symmetrical burners. A further deterioration of 32% is to be expected due to real mixture quality fluctuations and inhomogeneous inflow conditions. Finally, the findings demonstrate the model’s potential for designing efficient surface-stabilized burners and lay the groundwork for future 3D simulations in the pursuit of sustainable heating solutions.
Keywords: hydrogen combustion, flashback, flame stability, perforated flame holder, gas condensing boiler
Published in DKUM: 19.05.2025; Views: 0; Downloads: 6
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4. Natural Deep Eutectic Solvent-Based Matrix Solid Phase dispersion (MSPD) extraction for determination of bioactive compounds from sandy everlasting (Helichrysum arenarium L.) : a case of stability studyMilena Ivanović, Peter Krajnc, Aleš Mlinarič, Maša Islamčević Razboršek, 2022, original scientific article Abstract: In the present study, vortex-assisted matrix solid-phase dispersion (VA-MSPD) extraction
was used to isolate the major bioactive compounds from H. arenarium. To reduce the negative environmental impact of the conventionally used organic solvents, four different choline chloride-based
natural deep eutectic solvents (NADES) were investigated as possible eluents. The most influential
VA-MSPD extraction parameters: stationary phase (adsorbent), adsorbent/sample ratio, vortex time,
and volume of extraction solvent were systematically optimized. Ultrasound-assisted extraction
with 80% MeOH was used as the standard method for the comparison of results. The stability of the
obtained extracts was studied over a period of 0 to 60 days at three different temperatures (−18 ◦C,
4
◦C, and 25 ◦C). All extracts were evaluated both spectrophotometrically (determination of total
phenolic content (TPC) and antioxidant activity by ABTS and FRAP assay) and chromatographically
(HPLC-UV). NADES based on choline chloride and lactic acid (ChCl-LA) was selected as the most
effective extractant, with a determined TPC value of its extract of 38.34 ± 0.09 mg GA/g DW (27%
higher than the methanolic VA-MSPD extract) and high antioxidant activity. The content of individual phenolic compounds (chlorogenic acid, dicaffeoylquinic acid isomers, naringenin isomers,
and chalcones) in the ChCl-LA extract, determined by HPLC-UV, was comparable to that of the
conventionally obtained one. Moreover, the stabilization effect of ChCl-LA was confirmed for the
studied compounds: chlorogenic acid, naringenin-40
-O-glucoside, tomoroside A, naringenin-5-Oglucoside, isosalipurposide, and naringenin. The optimum VA-MSPD conditions for the extraction of
H. arenarium polyphenols were: florisil/sample ratio of 0.5/1, a vortex time of 2 min, and an elution
volume of ChCl-LA of 10 mL.
Keywords: matrix solid phase dispersion extraction, MSPD, natural deep eutectic solvents, NADES, extraction optimization, sandy everlasting, phenolic compounds, stability studies, antioxidant activity
Published in DKUM: 09.05.2025; Views: 0; Downloads: 9
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5. Suckling behaviour of piglets affected by body weight and sexMartina Dobaj Gomboc, Janko Skok, Dejan Škorjanc, Maja Prevolnik Povše, 2023, original scientific article Abstract: Piglet suckling behaviour has been extensively studied, but surprisingly, there are not many studies that specifically consider body weight and sex in this context. These two basic individual characteristics have been considered more as supporting data but not as main factors. Therefore, the objective of the present research was to examine the effect body weight on suckling behaviour of piglets during lactation separately by sex. The study comprised 14 litters with a total of 158 piglets (85 male, 73 female, litter size 6−15 piglets). Suckling behaviour was described in terms of suckling position (the teat at which the piglet suckled during suckling), suckling territory (the range two outermost suckling positions of the piglet encompasses) and suckling
stability (the tendency to suckle successively at the same position), and was observed in six periods: 0−3, 4−7, 8−10, 11−14, 15−21 and 22−32 days of age. In each period, piglets were also weighed. The udder was divided into three areas: anterior (1st-2nd teat pair), middle (3rd-5th teat pair) and posterior (6th-8th teat pair). Body weight affected suckling behaviour differently in male and female piglets (i.e., all traits in females, suckling stability only in males). The relative body weight of females decreased significantly from the anterior towards the posterior part. Heavy females (but not males) suckled considerably more frequently on the anterior area. Heavier piglets (male and female) established more stable suckling order. Suckling territory of males was quite large, but did not differ among body weight classes. Interestingly, light females visited significantly larger suckling territory than heavy females. The present results fill a gap in the otherwise broad knowledge of pig suckling behaviour, which is of great importance for litter management during lactation, especially when cross-fostering is implemented. In this context, knowledge of the detailed role of sex and body weight is of particular importance because breeders rely mainly on basic body traits when managing litters.
Keywords: pig, lactation, body weight, sex, suckling position, suckling stability, suckling territory
Published in DKUM: 25.04.2025; Views: 0; Downloads: 3
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6. Geotechnical aspects of N(H)bSs for enhancing Sub-Alpine mountain climate resilienceTamara Bračko, Primož Jelušič, Bojan Žlender, 2025, original scientific article Abstract: Mountain resilience is the ability of mountain regions to endure, adapt to, and recover from environmental, climatic, and anthropogenic stressors. Due to their steep topography, extreme weather conditions, and unique biodiversity, these areas are particularly vulnerable to climate change, natural hazards, and human activities. This paper examines how nature-based solutions (NbSs) can strengthen slope stability and geotechnical resilience, with a specific focus on Slovenia’s sub-Alpine regions as a case study representative of the Alps and similar mountain landscapes worldwide. The proposed Climate-Adaptive Resilience Evaluation (CARE) concept integrates geomechanical analysis with geotechnical planning, addressing the impacts of climate change through a systematic causal chain that connects climate hazards, their effects, and resulting consequences. Key factors such as water infiltration, soil permeability, and groundwater dynamics are identified as critical elements in designing timely and effective NbSs. In scenarios where natural solutions alone may be insufficient, hybrid solutions (HbSs) that combine nature-based and conventional engineering methods are highlighted as essential for managing unstable slopes and restoring collapsed geostructures. The paper provides practical examples, including slope stability analyses and reforestation initiatives, to illustrate how to use the CARE concept and how NbSs can mitigate geotechnical risks and promote sustainability. By aligning these approaches with regulatory frameworks and climate adaptation objectives, it underscores the potential for integrating NbSs and HbSs into comprehensive, long-term geotechnical strategies for enhancing mountain resilience.
Keywords: mountain resilience, climate change, nature-based solutions (NbSs), hybrid solutions (HbSs), geotechnical planning, slope stability, landslides
Published in DKUM: 31.03.2025; Views: 0; Downloads: 9
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8. Macroprudential policy versus other economic policiesEva Lorenčič, Mejra Festić, 2021, review article Abstract: After the global financial crisis of 2007, macroprudential policy instruments have gained in recognition as a crucial tool for enhancing financial stability. Monetary policy, fiscal policy, and microprudential policy operate with a different toolkit and focus on achieving goals other than the stability of the financial system as a whole. In ligh of this, a fourth policy – namely macroprudential policy – is required to mitigate and prevent shocks that could destabilize the financial system as a whole and compromise financial stability. The aim of this paper is to contrast macroprudential policy with other economic policies and explain why other economic policies are unable to attain financial stability, which in turn justifies the need for a separate macroprudential policy, the ultimate goal whereof is precisely financial stability of the financial system as a whole. Our research results based on the descriptive research method indicate that, in order to prevent future financial crises, it is indispensable to combine both the microprudential and the macroprudential approach to financial stability. This is because the causes of the crises are often such that they cannot be prevented or mitigated by relying only on microprudential or only on macroprudential policy instruments.
Keywords: macroprudential policy, monetary policy, microprudential policy, financial stability
Published in DKUM: 30.09.2024; Views: 0; Downloads: 21
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9. The impact of seven macroprudential policy instruments on financial stability in six euro area economiesEva Lorenčič, Mejra Festić, 2021, original scientific article Abstract: The aim of this paper is to investigate whether macroprudential policy instruments can influence the credit growth rate and hence financial stability. We use a fixed effects panel regression model to test the following hypothesis for six euro area economies (Austria, Finland, Germany, Italy, Netherlands and Spain) during time span 2010 Q3 to 2018 Q4: “Macroprudential policy instruments (degree of maturity mismatch; interbank loans as a percentage of total loans; leverage ratio; non-deposit funding as a percentage of total funding; loan-to-value ratio; loan-to-deposit ratio; solvency ratio) enhance financial stability, as measured by credit growth”. Our empirical results suggest that the degree of maturity mismatch, non-deposit funding as a percentage of total funding, loan-to-value ratio and loan-to-deposit ratio exhibit the predicted impact on the credit growth rate and therefore on financial stability. On the other hand, interbank loans as a percentage of total loans, leverage ratio, and solvency ratio do not exhibit the expected impact on the response variable. Since only four regressors (out of seven) have the signs predicted by our hypothesis, we can only partly confirm it.
Keywords: macroprudential policy, macroprudential instruments, systemic risk, financial stability
Published in DKUM: 26.09.2024; Views: 0; Downloads: 13
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10. Solar irradiance stability factorsBorut Jereb, 2024, original scientific article Abstract: In the field of renewable energies, the logistical intricacies of production, as well as the use and storage of photovoltaic energy, have become critical issues. In addition to sheer quantity, the stability of this type of energy is a crucial factor in ensuring the reliability and consistency of power generation. This paper defines Solar Irradiance Stability Factors (SISFs) as indicators complementing electricity production. When planning solar energy production in each geographical area, both the quantity and stability of solar irradiance are necessary for exploitation and determining the quality of solar irradiance. While the average production of solar energy per unit area in each time interval is a widely used parameter in daily practice, the observation of the amplitude of solar irradiance and its influence on energy production in the observed time interval is currently still rare. The SISFs defined in this article are new metrics that mainly depend on the meteorological variability in an area, and the observed time intervals should be in the range of seconds, minutes, or even hours. Larger time
intervals are not helpful for the stability of solar irradiance in energy production and logistics from the source to the destination. They provide a complementary and more accurate measure of how suitable a particular geographical area is for producing solar energy.
Keywords: solar irradiance, stability metrics, photovoltaic energy, meteorological variability, geographical area
Published in DKUM: 23.09.2024; Views: 0; Downloads: 45
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