| | SLO | ENG | Cookies and privacy

Bigger font | Smaller font

Search the digital library catalog Help

Query: search in
search in
search in
search in
* old and bologna study programme

Options:
  Reset


1 - 10 / 125
First pagePrevious page12345678910Next pageLast page
1.
The distribution of minerals in crucial plant parts of various elderberry (Sambucus spp.) interspecific hybrids
Nataša Imenšek, Vilma Sem, Mitja Kolar, Anton Ivančič, Janja Kristl, 2021, original scientific article

Abstract: In view of growing requirements of the food industry regarding elderberries (genusSambucus), a need to increase their productivity and improve their chemical composition has emerged.With this purpose in mind, numerous elderberry interspecific hybrids have been created. In thepresent work, the content of minerals in their crucial plant parts was studied. It was also investigatedwhether superior genotypes regarding the mineral composition of berries and inflorescences could bepredicted at early stages of plant development. The results showed that elderberry leaves containedthe highest amounts of Ca, Mg, Mn, Zn, and Sr, while K and P were predominant in fruit stalks.Fe and Al prevailed in roots and Cu in bark. Although berries showed lower mineral contentcompared to other plant parts, their mineral content is not negligible and could be comparable toother commonly consumed berries. Genotypes with a favorable mineral content of inflorescencesand berries could be predicted on the basis of known mineral composition of their shoots and leaves.The study also indicates thatS. nigragenotypes and the majority of interspecific hybrids analyzedare suitable for further genetic breeding or cultivation.
Keywords: interspecific hybrids, minerals, plant parts, elderberry, Sambucus
Published in DKUM: 20.08.2024; Views: 70; Downloads: 9
URL Link to full text
This document has many files! More...

2.
Ozonation of amoxicillin and ciprofloxacin in model hospital wastewater to increase biotreatability
Severina Aleksić, Andreja Žgajnar Gotvajn, Katarina Premzl, Mitja Kolar, Sonja Šostar-Turk, 2021, original scientific article

Abstract: Amoxicillin (AMX) and Ciprofloxacin (CIP) are antibiotics commonly used in human medicine with high environmental toxicity and poor biodegradability. They have been found in various hospital effluents and groundwater, and their environmental impact is still not fully understood. In this work, we investigated the possibility of treating model wastewaters containing the antibiotics AMX and CIP using ozonation, with the addition of H$_2$O$_2$ under various conditions, including different pH values, H$_2$O$_2$, and ozone dosages. The quantification of and treatment efficacy for antibiotic removal were determined via solid phase extraction followed by chromatographic separation by liquid chromatography coupled with tandem triple quadrupole mass spectrometry (LC/MS/MS). This analytical system is quite efficient for the detection of all major antibiotic classes, even if they are present at very low concentrations. The efficiency of ozonation was determined by measuring the TOC (Total Organic Carbon) changes after ozonation of the model wastewater and by measuring the concentration of the two antibiotics. In a sequential activated sludge process of ozone-treated model wastewater, almost complete TOC removal and an overwhelming decrease in antibiotic concentrations (up to 99%) were observed. Ozonation resulted in complete removal of AMX and CIP in less than 30 and 120 min, respectively. The results of this work indicate that ozonation could be a suitable pretreatment method to reduce the toxicity of contaminants (AMX and CIP) and improve the biodegradability of hospital wastewater.
Keywords: antibiotics, amoxicillin, AMX, ciprofloxacin, CIP, hospital wastewater, hydrogen peroxide, ozone, sludge, water treatment
Published in DKUM: 06.08.2024; Views: 75; Downloads: 14
URL Link to full text
This document has many files! More...

3.
Analizna kemija II in industrijska analiza : navodila za vaje
Maša Islamčević Razboršek, Mitja Kolar, 2023

Abstract: Gradivo obsega navodila za sledeče vaje: potenciometrično titracijo H3PO4 z NaOH, potenciometrično določanje koncentracije bromidnih ionov, konduktometrične titracije, elektrogravimetrijo, spektrofotometrično določitev železa, atomsko absorpcijsko spektroskopijo (AAS), atomsko emisijsko spektroskopijo (AES), spektroskopsko določitev zmesi benzena in toluena, ionsko kromatografijo in plinsko kromatografijo. Navodila za vaje so napisana tako, da omogočajo študentom samostojno delo, saj so poleg samega eksperimentalnega dela vključene tudi kratke teoretične osnove, ki so potrebne za samo razumevanje analizne metode, vključene so pa tudi skice in sheme instrumentov, kar omogoča študentu lažje razumevanje in delo v laboratoriju. Struktura gradiva je zasnovana tako, da vodi bralca od namena dela preko osnov do praktičnega eksperimentiranja in na koncu do zbranih novih pojmov, ki so v veliko pomoč pri študiju in pripravi na preverjanje znanja. Navodilom so dodana tudi navodila za varno delo v laboratoriju, pregled simbolov nevarnih snovi, napotki za prvo pomoč, inventarni list in izbrani viri s področja analizne kemije.
Keywords: potenciometrija, potenciometrična titracija, konduktometrija, konduktometrična titracija, elektrogravimetrija, spektrofotometrija, atomska absorpcijska spektroskopija, atomska emisijska spektroskopija, ionska kromatografija, plinska kromatografija
Published in DKUM: 02.10.2023; Views: 617; Downloads: 100
.pdf Full text (4,67 MB)
This document has many files! More...

4.
Telesna aktivnost, antioksidanti in oksidativni stres
Vesna Mila Meden, Vesna Rauter, 2022

Abstract: Med telesno aktivnostjo se sproščajo reaktivne zvrsti; obseg njihovega nastanka je povezan z značilnostmi telesne vadbe. Sproščanje reaktivnih zvrsti, ki presega zmožnost antioksidativne obrambe, izzove oksidativni stres. Ravnovesje med obsegom sproščanja reaktivnih zvrsti in antioksidativno obrambo je v fizioloških razmerah pomaknjeno nekoliko na stran oksidativnih procesov. Dve skrajnosti telesne aktivosti omenjeno ravnovesje rušita: akutna, visoko intenzivna telesna aktivnost in telesna neaktivnost. Izziv vrednotenja stanja oksidativnega stresa v organizmu je izjemno aktualen. Izsledki lastnih raziskav na področju antioksidantov usmerjajo k nujnosti interdisciplinarnega pristopa k tovrstnim raziskavam. Rezultati raziskave so primerjani z dognanji raziskovalcev v svetovnem prostoru, zato so predstavljena znanja izrazito aktualna. Z namenom, da se spodbudi radovednost in navdušenje do raziskovanja, vsebina še posebej nagovarja populacijo mladih, predvsem študentov. Izobraževanje o ključni vlogi telesne aktivnosti pri ohranjanju homeostaze in posledično zdravja in dolgoživosti spada med obvezne vsebine predmetov na vseh študijskih programih univerz in visokošolskih institucij. Športne igre naj postanejo temeljni povezovalni dejavnik v izobraževalnem procesu, izkustveno izobraževanje naj povezuje telesno aktivnost s sleherno vsebino predmetov. Malo nam v življenju koristijo obširna znanja, če ignoriramo osnove, ki trajnostno določajo zdravje in dobro počutje slehernega posameznika. Izgradnja uspešne kariere naj vselej temelji na redni telesni aktivnosti zmerne intenzivnosti.
Keywords: trajnostna priporočena telesna aktivnost, antioksidanti, oksidativni stres, antioksidativni stres, redoks status, hormeza, avtofagija, cirkadiani ritem
Published in DKUM: 29.08.2022; Views: 835; Downloads: 168
.pdf Full text (14,20 MB)
This document has many files! More...

5.
Kemijske analizne metode v kmetijstvu in toksične snovi v ekosistemih : navodila za laboratorijske vaje
Janja Kristl, 2022

Abstract: Navodila za vaje dopolnjujejo nekatere vsebinske sklope predavanj pri predmetih Kemijske analitične metode v kmetijsvtu in Toksične snovi v ekosistemih. Študentu pomagajo razumeti posamezne pojme (ekstrakcija, atomska absorpcijska spektrometrija, molekulska absorpcijska spektrometrija, tekočinska kromatografija, kislinski razklop) in laboratorijske postopke. V gradivu so opisani postopki priprave vzorcev in kvantitativne določitve natrijevega klorida, proteinov, skupnih fenolov, sladkorjev, oksalatov, vodikovega cianida v vzorcih živil in žveplovega dioksida v vinu. Vključena je tudi kvalitativna določitev nitrata in nitrita v ekstraktih živil ter kvalitativni testi za ugotavljanje prisotnosti naravnih in sintetičnih barvil. Vsebina zajema tudi določitev rastlinam dostopnega bakra ter vodotopne in biodostopne frakcije svinca v talnih vzorcih.
Keywords: natrijev klorid, proteini, oksalati, vodikov cianid, naravna in sintetična barvila, fenoli, žveplov dioksid, svinec, baker, nitrat
Published in DKUM: 15.02.2022; Views: 1159; Downloads: 301
.pdf Full text (4,18 MB)
This document has many files! More...

6.
Procesi odstranjevanja antibiotikov iz bolnišničnih odpadnih vod
Severina Stavbar, 2018, doctoral dissertation

Abstract: Ostanki antibiotikov in drugih zdravil, postajajo vse resnejši problem, saj jih najdemo v izpustih iz farmacevtskih in proizvodnih obratov, bolnišnic in odplakah iz čistilnih naprav. Različne študije so pokazale, da so ostanki antibiotikov prisotni v odpadnih in površinskih vodah, zadnje študije pa kažejo trend zviševanja tudi v tleh, podtalnici ter pitni vodi. Čeprav so izmerjene koncetracije v širokem koncentracijskem območju od ng/L do µg/L, so lahko nekateri razgradni produkti aktivnih snovi celo bolj toksični kot izvorna snov. Predhodne študije so pokazale, da so najvišje koncentracije antibiotikov v bolnišničnih odpadnih vodah. Za odstranitev takšnih onesnaževal pa obstoječe čistilne naprave niso primerne, saj velike količine antibiotikov ostajajo v vodi tudi po čiščenju. V doktorski disertaciji so predstavljeni trije procesi odstranjevanja teh onesnaževal iz bolnišničnih odpadnih vod. Glavni namen je bil poiskati napredne, izvedljive metode za odstranitev izbranih antibiotikov iz bolnišnične odpadne vode. V prvem delu smo se osredotočili na postopek čiščenja s sub in super-kritično oksidacijo, kjer smo preučili procesne parametre: vpliv temperature, tlaka, pretoka in časa. V drugem delu smo opravili postopek ozonacije, kjer smo spremljali učinkovitost čiščenja odpadne vode s spreminjanjem pH vzorca, različnimi odmerki ozona ter dodatek vodikovega peroksida (H2O2). V tretjem delu smo za čiščenje sintetično pripravljene bolnišnične odpadne vode uporabi aerobni reaktor, kjer smo iskali optimalen bivalni čas. Vsebnost antibiotikov smo po vsaki metodi čiščenja določali z optimiranimi LC-MS/MS analiznimi tehnikami. V zadnjem delu doktorske disertacije smo vse omenjene postopke čiščenja implementirali na realnem vzorcu bolnišnične odpadne vode. Vsebnost antibiotika v realnem vzorcu pred in po čiščenju smo določali z ekstrakcijo na trdni fazi v povezavi z optimirano LC-MS/MS tehniko. Na koncu smo izvedli še test inhibicije porabe kisika z aktivnim blatom za oksidacijo ogljika in amonija, s katerim smo poskušali ugotoviti, toksičen vpliv očiščene vode na mikrooganizme v aktivnem blatu.
Keywords: Antibiotiki, Bolnišnična odpadna voda, Sub-kritična oksidacija, Super-kritična oksidacija, Ozonacija, Aerobni reaktor, LC-MS/MS, Test toksičnosti
Published in DKUM: 20.06.2018; Views: 2030; Downloads: 280
.pdf Full text (2,60 MB)

7.
Development of analytical methods for simultaneous identification and determination of phenolic compounds
Milena Ivanović, 2018, doctoral dissertation

Abstract: The objective of this doctoral dissertation was to develop different analytical approaches for the extraction, separation, identification and quantitative determination of various phenolic compounds from different plants and their products. This dissertation is divided into the following four major segments, which, to some extent, can stand alone, but when it comes to the research, they are mutually very related: - Segment 1: Short-term (up to 24 h) and long-term (up to 1 month) stability studies of trans-caffeic acid (trans-CA) and trans-ferulic acid (trans-FA) dissolved in two organic solvents (methanol and tetrahydrofuran) and exposed to a range of storage conditions (temperature, organic solvents used, influence of daylight and UV irradiation) were performed for the first time. Gas chromatography with mass spectrometry (GC-MS) was used to study the degradation of the samples and structural identification of the degradation products. - Segment 2: The research within this segment focused on the optimization of a simple, fast and quantitative extraction method for the isolation of phenolic acids (PAs) from Slovenian red wine samples. Different extraction techniques were tested, and solid phase extraction (SPE) using HLB cartridges was selected as the optimal technique. For the identification and quantification of extracted analytes, the GC-MS method was optimized and validated. Different statistical and chemometrical tools were applied, and the wines were classified according to the Slovenian wine-growing regions and vine varieties. - Segment 3: The main goal within this research segment was the development of an ultrasound-assisted extraction (UAE) method for the isolation of different polyphenol classes from coriander fruits. Additionally, for the isolation of total PAs (free and bound), two analytical steps were applied: UAE alkaline hydrolysis and clean-up using SPE HLB cartridges. The response surface methodology (RSM) combined with a Box-Behnken experimental design (BBD) were used for the optimization of the alkaline hydrolysis and for increasing the extraction yields of the PAs. In this way, most influencing factors (temperature, sonication time and NaOH concentration) were studied as independent variables. Extracted PAs were determined using the previously optimized GC-MS method. - Segment 4: The main goal of this segment of the dissertation was to show the application of deep eutectic solvents (DESs) as a ‘green’ alternative to the conventional organic solvents for the isolation of phenolic compounds from plants such as Aronia melanocarpa (dried chokeberry) and Olea europaea (olive leaves). Different extraction techniques and instrumental methods were applied for the determination of phenolic profiles. Phenols from chokeberries were obtained through UAE. Furthermore, for the simultaneous identification and quantitative determination of 21 different phenolic compounds from Aronia melanocarpa, the HPLC-UV method was optimized and validated. On the other hand, microwave-assisted extraction (MAE) was used to improve the extraction yields of phenolic compounds from olive leave samples, which were subsequently determined by using validated HPLC-DAD-ESI-TOF-MS method.
Keywords: phenolic compounds, phenolic acids, extraction, GC-MS, HPLC, method optimization, deep eutectic solvents, plant material
Published in DKUM: 11.04.2018; Views: 2385; Downloads: 177
.pdf Full text (5,10 MB)

8.
Določanje in kemometrijska analiza organskih spojinadsorbiranih na prašne delce PM10
Alen Miuc, 2017, doctoral dissertation

Abstract: Namen naše raziskave je bil določanje okolju nevarnih organskih spojin adsorbiranih na prašne delce PM10. Vzorce smo odvzeli v skladu s standardom SIST EN 12341:2014. Po gravimetrijskem določanju delcev PM10 smo vzorce uporabili še za določitev kemične sestave in preučitev pomembnih sezonskih razlik v sestavi organskih snovi, ki jih vsebujejo delci PM10. V ta namen smo razvili analizno metodo za določevanje organskih spojin v ekstraktih vzorcev prašnih delcev PM10 s plinsko kromatografijo in masno spektrometrijo. S pomočjo kemometrijskih metod smo določili pomembne sezonske in lokacijske razlike sestave organskih spojin v zraku nad Mariborom. Določali smo sestavo spojin, ki označujejo onesnaženost in ugotavljali, katere spojine so antropogenega izvora. Ugotavljali smo, kako se sestava razlikuje glede na letni čas in odvzemno mesto vzorčenja. PM10 je frakcija respirabilnih prašnih delcev s premerom 10 μm ali manj. Suspendirani delci v zraku so naravnega (gozd, cvetni prah, padavine, neurja, vegetacija, vulkanski pepel...) ali antropogenega izvora (emisije industrije, prometa, sežig fosilnih goriv, biomase, kmetijstvo). Glede na izvor delce razdelimo na primarne in sekundarne. Primarni delci se sproščajo v ozračje direktno. Velik del organskih aerosolov v atmosferi je mogoče pripisati sekundarnim organskim aerosolom (SOA), ki nastajajo pri oksidaciji hlapnih organskih spojin (VOC) z atmosferskimi oksidanti kot so O3, OH• radikali in NO3• radikali. Fotokemični procesi vplivajo na kemično sestavo organskih spojin in njihove fizikalno-kemijske lastnosti kot so hlapnost, higroskopičnost ali kondenzacijsko aktivnost SOA spojin. Zakonsko predpisana 24-urna mejna koncentracija za delce PM10 je 50 μg/m3. Preseganja dnevnih mejnih vrednosti PM10 so praviloma v zimskem letnem času. Povišana raven delcev PM10 je predvsem posledica lokalnih izpustov. Dve tretjini vseh izpustov delcev PM10 v Sloveniji je posledica kurjenja lesa gospodinjstev. Raziskovalno delo zaznave in določanja spojin organskih onesnaževal vključuje 120 standardno odvzetih vzorcev prašnih delcev (standard SIST EN 12341:2014) z uporabo nizko volumskega vzorčevalnika, ter analitsko določevanje s plinsko kromatografijo in masno spektrometrijo (GC/MS). Za določanje polarnih organskih spojin smo uporabili sililiranje kot kemijsko tehniko derivatizacije. Nabor organskih spojin v ekstraktih prašnih delcev PM10 vključuje maščobne kisline, n- in izo-alkane, ftalatne estre, siloksane, sterole, sladkorje, sladkorne alkohole, dikarboksilne kisline, spojine razgradnje lignina in lesnih smol, policiklične organske ogljikovodike, organske dušikove spojine ter produkte sekundarne oksidacije monoterpenskih spojin. S pomočjo kemijske karakterizacije smo določili sezonske in lokacijske razlike merilnih mest. Za proučevanje smo uporabili kemometrijske metode kot so korelacijska analiza, metoda glavnih osi, hierarhično razvrščanje, analiza variance (ANOVA). V toplejših letnih časih prevladujejo na prašnih delcih adsorbirane biogene spojine nad antropogenimi spojinami. Pozimi prevladujejo antropogene organske spojine. Najbolj reprezentativne spojine zimskih vzorcev zraka so: levoglukozan, manozan, spojine ftalatnih estrov, spojine razgradnje ligninov in palmitinska kislina. Poleti prevladujejo derivati sladkorjev in sladkornih alkoholov. Na razlike vzorcev glede na sestavo organskih spojin najbolj vplivajo spojine PAHov, 1,3,5-trifenilbenzen, pinonska kislina, DEHP, glicin, nonanojska kislina (C9:0), ter jabolčna kislina in adipinska kislina. V številnih vzorcih je bil prisoten razpotegnjen kromatografski vrh neločene kompleksne mešanice (NKM), ki se razlikuje glede na letni čas in sestavo. Izvor NKM pozimi pripisujemo kurjenju fosilnih goriv ter izpuhov motornih vozil, poleti pa fotooksidacijskim procesom monoterpenov. Do lokacijskih razlik v sestavi organskih spojin adsorbiranih na ekstraktih vzorcev PM10 prihaja zaradi različnih antropogenih in biogenih izpustov, obremenjenosti posamezne
Keywords: PM10, EN 12341, prašni delci, organske spojine, GC/MS.
Published in DKUM: 08.11.2017; Views: 2025; Downloads: 198
.pdf Full text (5,69 MB)

9.
Chemometric characterization of Slovenian red wines
Milena Ivanović, Anja Petek, Maša Islamčević Razboršek, Mitja Kolar, 2017, original scientific article

Abstract: Total phenolic (TPC), flavonoid (TFC) and tannin (TTC) contents, total $SO_2$, total acids, pH, and reducing sugars were measured in twenty five Slovenian red wines from three key wine producing regions, Podravje, Posavje and Primorska. The results were chemometrically analysed and the wines were classified according to wine growing region and vine variety. Principal component analysis proved that TPC, TFC and TTC contents were primarily responsible for variation in the wines. Additionally, linear discriminant analysis (LDA) was performed and resulted in the satisfactory classification of samples by both vine variety and region.
Keywords: Slovenian red wines, quality parameters of wine, polyphenols, chemometric analysis
Published in DKUM: 03.10.2017; Views: 1531; Downloads: 395
.pdf Full text (119,46 KB)
This document has many files! More...

10.
Simultaneous GC-MS determination of free and bound phenolic acids in Slovenian red wines and chemometric characterization
Milena Ivanović, Maša Islamčević Razboršek, Mitja Kolar, 2016, original scientific article

Abstract: Several phenolic acids (PAs), caffeic, vanillic, syringic, p-coumaric and ferulic acid, found in Slovenian red wines were studied using gas chromatography and mass spectrometry (GC-MS). For isolation of the PAs from wine samples, solid phase extraction (SPE) using hydrophilic modified styrene - HLB cartridges was used. The bound PAs were extracted after basic hydrolysis and o-coumaric acid was used as the internal standard (ISTD). The method developed was validated and the linear concentration range for all analytes was from 1 to 100 mg L$^{-1}$ with correlation coefficients above 0.999. We show that the method is repeatable (RSD<2%), recoveries were above 96%, and LOD and LOQ values were acceptable. In all of the wine samples tested, caffeic and p-coumaric acid were determined to be the predominant PAs (17-72 mg L$^{-1}$), while other compounds were found in lower concentrations. Principal Component Analysis (PCA) and Cluster Analysis (CLU) were used to study differences between wines related towards varieties and Slovenian wine regions. The results demonstrate that variety has more influence on PAs content than wine regions in Slovenian red wines.
Keywords: phenolic acids, Slovenian red wines, gas chromatography, mass spectrometry, PCA, CLU
Published in DKUM: 25.08.2017; Views: 2231; Downloads: 388
.pdf Full text (222,27 KB)
This document has many files! More...

Search done in 0.21 sec.
Back to top
Logos of partners University of Maribor University of Ljubljana University of Primorska University of Nova Gorica