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Osnove organske analize : skripta
Sebastijan Kovačič, 2023, drugo učno gradivo

Ključne besede: analizna kemija, organske snovi, organska analiza, učbeniki
Objavljeno v DKUM: 19.09.2023; Ogledov: 59; Prenosov: 6
.pdf Celotno besedilo (6,05 MB)

Kinetics study of hydrothermal degradation of PET waste into useful products
Maja Čolnik, Darja Pečar, Željko Knez, Andreja Goršek, Mojca Škerget, 2022, izvirni znanstveni članek

Opis: Kinetics of hydrothermal degradation of colorless polyethylene terephthalate (PET) waste was studied at two temperatures (300 °C and 350 °C) and reaction times from 1 to 240 min. PET waste was decomposed in subcritical water (SubCW) by hydrolysis to terephthalic acid (TPA) and ethylene glycol (EG) as the main products. This was followed by further degradation of TPA to benzoic acid by decarboxylation and degradation of EG to acetaldehyde by a dehydration reaction. Furthermore, by-products such as isophthalic acid (IPA) and 1,4-dioxane were also detected in the reaction mixture. Taking into account these most represented products, a simplified kinetic model describing the degradation of PET has been developed, considering irreversible consecutive reactions that take place as parallel in reaction mixture. The reaction rate constants (k1–k6) for the individual reactions were calculated and it was observed that all reactions follow first-order kinetics.
Ključne besede: PET waste, subcritical water, kinetics, degradation, TPA
Objavljeno v DKUM: 18.09.2023; Ogledov: 79; Prenosov: 4
.pdf Celotno besedilo (2,22 MB)
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Degradation of polyvinyl chloride (PVC) waste with supercritical water
Maja Čolnik, Petra Kotnik, Željko Knez, Mojca Škerget, 2022, izvirni znanstveni članek

Opis: The chemical degradation of PVC waste in SCW between 400 and 425 °C and reaction times from 30 to 60 min was studied. The PVC waste in SCW decomposed into the gas, oil, water soluble, and solid phases. The highest yield of the gas and oil phases was achieved at the temperature of 425 °C after 60 min. By increasing the reaction time at 400 °C, the yield of chloride ions in the aqueous phase increased and reached the maximum at 60 min. The gas and oil phases contained many valuable compounds similar to crude oil. Alkanes and chloroalkanes; alkenes, alicyclic, and aromatic hydrocarbons; as well as alcohols were the main groups of hydrocarbons in the oil phase, while the gas phase contained only light hydrocarbons (C1–C6), CO2, and small amounts of H2. This confirmed that the largest chlorine content remains in the aqueous phase and does not pass into the gas phase. It can be concluded that SCW presents effective decomposition media for plastic waste.
Ključne besede: polyvinyl chloride, supercritical water, chemical recycling, plastic waste
Objavljeno v DKUM: 18.09.2023; Ogledov: 55; Prenosov: 3
.pdf Celotno besedilo (1,09 MB)
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Chemical recycling of polyolefins waste materials using supercritical water
Maja Čolnik, Petra Kotnik, Željko Knez, Mojca Škerget, 2022, izvirni znanstveni članek

Opis: In the following work, the hydrothermal degradation of polypropylene waste (PP) using supercritical water (SCW) has been studied. The procedure was carried out in a high-pressure, high-temperature batch reactor at 425 °C and 450 °C from 15 to 240 min. The results show a high yield of the oil (up to 95%) and gas (up to 20%) phases. The gained oil phase was composed of alkanes, alkenes, cycloalkanes, aromatic hydrocarbons, and alcohols. Alkanes and alcohols predominated at 425 °C and shorter reaction times, while the content of aromatic hydrocarbons sharply increased at higher temperatures and times. The higher heating values (HHVs) of oil phases were in the range of liquid fuel (diesel, gasoline, crude and fuel oil), and they were between 48 and 42 MJ/kg. The gas phase contained light hydrocarbons (C1–C6), where propane was the most represented component. The results for PP degradation obtained in the present work were compared to the results of SCW degradation of colored PE waste, and the potential degradation mechanism of polyolefins waste in SCW is proposed. The results allowed to conclude that SCW processing technology represents a promising and eco-friendly tool for the liquefaction of polyolefin (PE and PP) waste into oil with a high conversion rate.
Ključne besede: polypropylene, polyolefins, supercritical water, plastics waste, chemical recycling
Objavljeno v DKUM: 18.09.2023; Ogledov: 58; Prenosov: 3
.pdf Celotno besedilo (3,44 MB)
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6th International Conference on Technologies & Business Models for Circular Economy : book of abstracts

Opis: The 6th International Conference on Technologies & Business Models for Circular Economy (TBMCE) was organized by the Faculty of Chemistry and Chemical Engineering, University of Maribor in collaboration with the Strategic Research and Innovation Partnership - Networks for the Transition into Circular Economy (SRIP- Circular Economy), managed by the Chamber of Commerce and Industry of Štajerska. The conference was held in Portorož, Slovenia, at the Grand Hotel Bernardin from September 6th to September 8th, 2023. The Netherlands joined us as a partner country of the conference. TBMCE 2023 was devoted to presentations of circular economy concepts, technologies and methodologies that contribute to the shift of business entities and society as a whole to a more responsible, circular management of resources. The conference program included panel discussions, plenary and keynote sessions, oral and poster presentations on the following topics: Sustainable energy, Biomass and alternative raw materials, Circular business models, Secondary raw materials and functional materials, ICT in Circular Economy, Processes and technologies. Panel discussions addressed following topics: Capture, storage or conversion of CO2 or H2?, The potential of small scale biorefining, Circular economy in construction – myth or real opportunity?, Importance of circular communities in international arena, Sector Coupling: pathways to integrated energy systems, Combating water pollution by plastic waste. The event was
Ključne besede: circular economy, sustainable development, processes and technologies, circular business models, research and development
Objavljeno v DKUM: 01.09.2023; Ogledov: 45; Prenosov: 26
.pdf Celotno besedilo (3,06 MB)
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Measurement of two-particle correlations of hadrons in ▫$e^+ e^-$▫ collisions at Belle
Y.-C. Chen, Marko Bračko, Samo Korpar, Peter Križan, Tomaž Podobnik, Marko Starič, Luka Šantelj, 2022, izvirni znanstveni članek

Opis: The measurement of two-particle angular correlation functions in high-multiplicity e+e− collisions at √s=10.52  GeV is reported. In this study, the 89.5  fb−1 of hadronic e+e− annihilation data collected by the Belle detector at KEKB are used. Two-particle angular correlation functions are measured in the full relative azimuthal angle (Δϕ) and three units of pseudorapidity (Δη), defined by either the electron beam axis or the event-shape thrust axis, and are studied as a function of charged-particle multiplicity. The measurement in the thrust axis analysis, with mostly outgoing quark pairs determining the reference axis, is sensitive to the region of additional soft gluon emissions. No significant anisotropic collective behavior is observed with either coordinate analyses. Near-side jet correlations appear to be absent in the thrust axis analysis. The measurements are compared to predictions from various event generators and are expected to provide new constraints to the phenomenological models in the low-energy regime.
Ključne besede: Particle & resonance production, Quark & gluon jets, Quark-gluon plasma
Objavljeno v DKUM: 24.08.2023; Ogledov: 123; Prenosov: 8
.pdf Celotno besedilo (634,71 KB)
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Bio-based processes for material and energy production from waste streams under acidic conditions
Zeynep Cetecioglu, Merve Atasoy, Adam Cenian, Gaweł Sołowski, Janja Trček, Aysenur Ugurlu, Jana Sedlakova-Kadukova, 2022, pregledni znanstveni članek

Opis: The revolutionary transformation from petrol-based production to bio-based production is becoming urgent in line with the rapid industrialization, depleting resources, and deterioration of the ecosystem. Bio-based production from waste-streams is offering a sustainable and environmentally friendly solution. It offers several advantages, such as a longer operation period, less competition for microorganisms, higher efficiency, and finally, lower process costs. In the current study, several biobased products (organic acids, biomethane, biohydrogen, and metal leachates) produced under acidic conditions are reviewed regarding their microbial pathways, processes, and operational conditions. Furthermore, the limitations both in the production process and in the scale-up are evaluated with future recommendations.
Ključne besede: bio-based production, acidogenic conditions, fermentation, organic acids, biohydrogen, biomethane, bioleaching
Objavljeno v DKUM: 24.08.2023; Ogledov: 62; Prenosov: 12
.pdf Celotno besedilo (1,39 MB)
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Antimicrobial resistance of Acetobacter and Komagataeibacter species originating from vinegars
Eva Cepec, Janja Trček, 2022, izvirni znanstveni članek

Opis: Consumers’ preference towards healthy and novel foods dictates the production of organic unfiltered bottled vinegar that still contains acetic acid bacteria. After ingesting vinegar, the bacteria come into close contact with the human microbiota, creating the possibility of horizontal gene transfer, including genetic determinants for antibiotic resistance. Due to the global spread of antimicrobial resistance (AMR), we analyzed the AMR of Acetobacter and Komagataeibacter species originating mainly from vinegars. Six antibiotics from different structural groups and mechanisms of action were selected for testing. The AMR was assessed with the disk diffusion method using various growth media. Although the number of resistant strains differed among the growth media, 97.4%, 74.4%, 56.4%, and 33.3% of strains were resistant to trimethoprim, erythromycin, ciprofloxacin, and chloramphenicol, respectively, on all three media. Moreover, 17.9% and 53.8% of all strains were resistant to four and three antibiotics of different antimicrobial classes, respectively. We then looked for antimicrobial resistance genes in the genome sequences of the reference strains. The most common genetic determinant potentially involved in AMR encodes an efflux pump. Since these genes pass through the gastrointestinal tract and may be transferred to human microbiota, further experiments are needed to analyze the probability of this scenario in more detail.
Ključne besede: acetic acid bacteria, Acetobacter, Komagataeibacter, antimicrobial resistance, trimethoprim resistance, erythromycin resistance, ciprofloxacin resistance, chloramphenicol resistance, ampicillin resistance, gentamicin resistance
Objavljeno v DKUM: 24.08.2023; Ogledov: 56; Prenosov: 10
.pdf Celotno besedilo (444,89 KB)
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Peripheral blood transcriptome in breast cancer patients as a source of less invasive immune biomarkers for personalized medicine, and implications for triple negative breast cancer
Helena Sabina Čelešnik, Uroš Potočnik, 2022, pregledni znanstveni članek

Opis: Transcriptome studies of peripheral blood cells can advance our understanding of the systemic immune response to the presence of cancer and the mechanisms underlying cancer onset and progression. This enables the identification of novel minimally invasive immune biomarkers for early cancer detection and personalized cancer management and may bring forward new immunotherapy options. Recent blood gene expression analyses in breast cancer (BC) identified distinct patient subtypes that differed in the immune reaction to cancer and were distinct from the clinical BC subtypes, which are categorized based on expression of specific receptors on tumor cells. Introducing new BC subtypes based on peripheral blood gene expression profiles may be appropriate, since it may assist in BC prognosis, the identification of patients likely to benefit from immunotherapy, and treatment efficacy monitoring. Triple-negative breast cancer (TNBC) is an aggressive, heterogeneous, and difficult-to-treat disease, and identification of novel biomarkers for this BC is crucial for clinical decision-making. A few studies have reported TNBC-enriched blood transcriptional signatures, mostly related to strong inflammation and augmentation of altered immune signaling, that can differentiate TNBC from other classical BC subtypes and facilitate diagnosis. Future research is geared toward transitioning from expression signatures in unfractionated blood cells to those in immune cell subpopulations.
Ključne besede: triple negative breast cancer, transcriptome, peripheral blood, PBMC, gene expression, immune biomarker
Objavljeno v DKUM: 23.08.2023; Ogledov: 65; Prenosov: 10
.pdf Celotno besedilo (1,74 MB)
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