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Carbonization of Class G well cement containing metakaolin under supercritical and saturated environments
Gregor Kravanja, Željko Knez, 2023, izvirni znanstveni članek

Ključne besede: well cement, carbonization, metakaolin, supercritical CO2, gas saturated solution, CaCo3
Objavljeno v DKUM: 15.04.2024; Ogledov: 120; Prenosov: 9
.pdf Celotno besedilo (14,25 MB)
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Ensiling, in vitro rumen digestion and soaking in slurry altered the germination capacity of Rumex obtusifolius seeds
Anastazija Gselman, Maksimiljan Brus, 2023, izvirni znanstveni članek

Opis: This study investigated whether the process of ensiling and in vitro digestion in rumen juice, as well as the response to soaking in pig or cattle slurry, affects the germination rate and germination energy of Rumex obtusifolius (broad-leaved dock) seeds. Seeds were subjected to different treatments (200 seeds each) in three experiments: (I) seed ensiling (8 weeks) followed by in vitro rumen digestion (24, 36 and 48 h); (II) the soaking of non-ensiled and ensiled seeds in cattle or pig slurry (2, 4 and 24 weeks); and (III) the in vitro rumen digestion (24, 36 and 48 h) of non-ensiled and ensiled seeds followed by soaking in cattle or pig slurry (24 weeks). The control treatment included untreated seed (0—non-ensiled seed; 0—no in vitro rumen digestion; and 0—no soaking in slurry). Germination tests (germination rate and germination energy) were then conducted in four replicates in the germination chamber under alternating day (20–35 °C for 14 h under light) and night conditions (17–20 °C for 10 h without light) at 75% relative humidity. Experiment I showed that ensiling significantly (p ≤ 0.001) reduced both the germination rate and germination energy of R. obtusifolius seeds. In addition, the length of in vitro digestion duration that the non-ensiled seeds were subjected to significantly (p ≤ 0.001) reduced their germination energy but not the total germination rate. However, the seeds that were subjected to the process of ensiling and in vitro digestion in the rumen lost their germination completely. The Experiment II investigated the effects of soaking non-ensiled seeds in slurry and showed that germination rates were comparable in pig and cattle slurry. Longer soaking times significantly reduced the germination rate, with no germination observed after 24 weeks. The Experiment III considered the combined effects of in vitro digestion and slurry soaking and showed that rumen digestion reduced the proportion of germinable seeds. Germination was inhibited in pig slurry, while in cattle slurry, a decreasing germination rate was observed with increasing digestion time.
Ključne besede: broad-leaved dock, in vitro rumen digestion, ensiling, pig and cattle slurry, seed germination
Objavljeno v DKUM: 05.04.2024; Ogledov: 226; Prenosov: 6
.pdf Celotno besedilo (293,08 KB)
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Improvement of biogas production utilizing a complex anaerobic digestion model and gradient-based optimization
Tina Kegl, Breda Kegl, Marko Kegl, 2024, izvirni znanstveni članek

Opis: : Anaerobic digestion (AD) is a promising technology for renewable energy production from organic waste. In order to maximize the produced biogas quantity and quality, this paper deals with the optimization of the AD process in a CSTR bioreactor of a full-scale biogas plant. For this purpose, a novel approach was adopted coupling, a highly complex BioModel for AD simulation, and a gradient-based optimization method. In order to improve AD performance, the dosages of various types of biological additives, the dosages of inorganic additives, and the temperature in the bioreactor were optimized in three different scenarios. The best biogas quality was obtained using multi-objective optimization, where the objective function involves the following two conflicting objectives: the maximization of biogas production and minimization of the needed heating energy. The obtained results show that, potentially, the content of CH4 can be increased by 11%, while the contents of H2, H2S, and NH3 can be reduced by 30%, 20%, and 81% when comparing the simulation results with the experimental data. The obtained results confirm the usefulness of the proposed approach, which can easily be adapted or upgraded for other bioreactor types.
Ključne besede: additives, anaerobic digestion, approximation method, BioModel, complex substrate, gradient-based optimization, process conditions
Objavljeno v DKUM: 12.03.2024; Ogledov: 215; Prenosov: 15
.pdf Celotno besedilo (7,33 MB)
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Variable-length differential evolution for numerical and discrete association rule mining
Uroš Mlakar, Iztok Fister, Iztok Fister, 2023, izvirni znanstveni članek

Opis: This paper proposes a variable-length Differential Evolution for Association Rule Mining. The proposed algorithm includes a novel representation of individuals, which can encode both numerical and discrete attributes in their original or absolute complement of the original intervals. The fitness function used is comprised of a weighted sum of Support and Confidence Association Rule Mining metrics. The proposed algorithm was tested on fourteen publicly available, and commonly used datasets from the UC Irvine Machine Learning Repository. It is also compared to the nature inspired algorithms taken from the NiaARM framework, providing superior results. The implementation of the proposed algorithm follows the principles of Green Artificial Intelligence, where a smaller computational load is required for obtaining promising results, and thus lowering the carbon footprint.
Ključne besede: association rule mining, differential evolution, data mining, variable-lenght solution representation, green AI
Objavljeno v DKUM: 18.01.2024; Ogledov: 272; Prenosov: 7
.pdf Celotno besedilo (2,39 MB)
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Microwave Synthesis of Poly(Acrylic) Acid-Coated Magnetic Nanoparticles as Draw Solutes in Forward Osmosis
Sabina Vohl, Irena Ban, Mihael Drofenik, Hermina Bukšek, Sašo Gyergyek, Irena Petrinić, Claus Hélix-Nielsen, Janja Stergar, 2023, izvirni znanstveni članek

Opis: Polyacrylic acid (PAA)-coated magnetic nanoparticles (MNP@PAA) were synthesized and evaluated as draw solutes in the forward osmosis (FO) process. MNP@PAA were synthesized by microwave irradiation and chemical co-precipitation from aqueous solutions of Fe2+ and Fe3+ salts. The results showed that the synthesized MNPs have spherical shapes of maghemite Fe2O3 and superparamagnetic properties, which allow draw solution (DS) recovery using an external magnetic field. Synthesized MNP, coated with PAA, yielded an osmotic pressure of ~12.8 bar at a 0.7% concentration, resulting in an initial water flux of 8.1 LMH. The MNP@PAA particles were captured by an external magnetic field, rinsed in ethanol, and re-concentrated as DS in repetitive FO experiments with deionized water as a feed solution (FS). The osmotic pressure of the re-concentrated DS was 4.1 bar at a 0.35% concentration, resulting in an initial water flux of 2.1 LMH. Taken together, the results show the feasibility of using MNP@PAA particles as draw solutes.
Ključne besede: magnetic nanoparticles, microwave synthesis, polyacrilic acid, osmotic pressure, draw solution, forward osmosis
Objavljeno v DKUM: 05.12.2023; Ogledov: 349; Prenosov: 15
.pdf Celotno besedilo (3,00 MB)
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Synthesis of magnetic nanoparticles with covalently bonded polyacrylic acid for use as forward osmosis draw agents
Irena Ban, Mihael Drofenik, Hermina Bukšek, Irena Petrinić, Claus Hélix-Nielsen, Sabina Vohl, Sašo Gyergyek, Janja Stergar, 2023, izvirni znanstveni članek

Opis: Multicoated magnetite (Fe3O4) magnetic nanoparticles (MNPs) with polyacrylic acid (PAA) as a terminal hydrophilic ligand were synthesized and examined for use as a draw solution (DS) agent in forward osmosis (FO). After coating superparamagnetic iron-oxide MNPs with (3-aminopropyl)triethoxysilane (APTES) the carboxyl groups of PAA were bound to APTES amino groups via the crosslinker 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) forming a peptide bond resulting in stable water-soluble particles (MNP@APTES@PAA) with a concentration-normalised osmotic pressure of 1.56 bar L g−1. The MNP@APTES@PAA solution was evaluated as a DS in two FO filtrations with deionized (DI) water as a feed solution (FS): one using freshly prepared MNP@APTES@PAA and one using magnetically recovered (re-concentrated) MNP@APTES@PAA. The resulting MNP@APTES@PAA nanocomposites exhibit good colloidal stability in aqueous solution with a concentration-normalized osmotic pressure of 1.56 bar L g−1. This is 12-fold higher than that in our previous studies of poly-sodium-acrylate coated MNPs and 3-fold higher than that of citric acid coated MNPs. The water recoveries of the two filtrations were 25.7% and 13.6%, respectively, after 2 h of FO filtration time resulting in a DS osmotic pressure of 2.5 bar with a concentration of 4.3 g L−1 and a DS osmotic pressure of 2.6 with a concentration of 3.7 g L−1 respectively.
Ključne besede: magnetic nanoparticle, forward osmosis, draw solution, osmose
Objavljeno v DKUM: 16.08.2023; Ogledov: 358; Prenosov: 8
.pdf Celotno besedilo (1,92 MB)
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Optimizacija priprave proteinov krvne plazme z razgradnjo na peptide v raztopini za proteomsko analizo z masno spektrometrijo : diplomsko delo univerzitetnega študijskega programa I. stopnje
Eva Zajšek, 2023, diplomsko delo

Opis: V diplomskem delu sta predstavljena danes najpogostejša načina priprave vzorcev proteinov z razgradnjo na peptide za proteomsko analizo z masnim spektrometrom: SDS PAGE in stopenjska priprava v raztopini, ki vključuje denaturacijo, redukcijo, alkilacijo proteinov in njihovo cepitev na peptide s tripsinom. Naš namen je bil skrajšati, poenostaviti in poceniti v znanstveni literaturi opisani protokol stopenjske priprave vzorcev proteinov v raztopini, vendar kljub temu ohraniti dobro razgradnjo proteinov in identifikacijo z masnim spektrometrom. V delu je tako podrobneje prikazana analiza optimizacije priprave vzorcev v raztopini: različni reagenti, različne koncentracije, združevanje korakov, dodajanje korakov, različne temperature in različno dolge inkubacije. Rezultati kažejo, da protokola ne moremo skrajšati na račun časa inkubacije tripsina, vendar pa lahko to storimo z združitvijo korakov denaturacije, redukcije in alkilacije ter skrajšanim časom inkubacije teh korakov. Kot boljši alkilacijski reagent se je v primerjavi z jodoacetamidom (IAM) zaradi manjšega števila neželenih modifikacij izkazal kloroacetamid (CAM), za oba reagenta pa je primerna koncentracija pod 10 mM. Ugotovili smo, da dodaten korak prekinitve alkilacije z ditiotreitolom (DTT) zaradi prihranka časa in kemikalij ni primeren, saj ne zmanjša števila neželenih modifikacij. Povzeti protokol smo nekoliko pocenili z zamenjavo alkilacijskih reagentov, saj je kloroacetamid (CAM) cenejši in ga je na voljo za več eksperimentov, sicer pa ceno celotnega eksperimenta določa predvsem poraba tripsina, čigar cena znaša okrog 2,23 EUR za 1 μL.
Ključne besede: proteomika, SDS PAGE, in-solution-digestion, reagenti, masna spektroskopija, priprava vzorcev
Objavljeno v DKUM: 31.03.2023; Ogledov: 563; Prenosov: 43
.pdf Celotno besedilo (4,45 MB)

A general analytical solution to the one-dimensional consolidation problem for unsaturated soil under various loading conditions
Jiwei Li, Changfu Wei, Yanlin Zhao, 2018, izvirni znanstveni članek

Opis: A general analytical solution is developed for the onedimensional consolidation problem of unsaturated soil under various time-dependent loading conditions based on a differential transformation method (DTM). In particular, analytical solutions are obtained for different relationships between the coefficients in the governing equations for unsaturated soil consolidation. The Fourier series expansion technique is adopted to account for both the continuous differentiable loading and the periodic piecewise loading. A comparison between the results of the current solution and the existing theoretical solution indicates that the proposed solution yields excellent results, while it is straightforward to obtain the analytical solution of the unsaturated consolidation problems. It was also found that the variations in the coefficients in the governing equations can significantly influence the dissipation of both the excess pore-air pressure and the excess pore-water pressure, though the magnitudes of their variations are different.
Ključne besede: one-dimensional consolidation problem, unsaturated soil, analytical solution, time-dependent loading
Objavljeno v DKUM: 11.10.2018; Ogledov: 1364; Prenosov: 520
.pdf Celotno besedilo (814,44 KB)
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