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Uporaba naprednih oksidacijskih postopkov za razbarvanje odpadnih voda
Nejc Lebar, 2019, diplomsko delo

Opis: Industrija je največji porabnik vode in hkrati največji proizvajalec odpadnih vod. Odpadne vode iz industrije vsebujejo kompleksne snovi, ki jih v konvencionalnih čistilnih napravah ni mogoče odstraniti. Za potrebe odstranjevanja takšnih snovi se razvijajo naprednejši postopki čiščenja. V diplomski nalogi smo se osredotočili na čiščenje obarvanih odpadnih vod v tekstilni industriji. Za razbarvanje teh smo uporabili napredni oksidacijski postopek (AOP) H_2 O_2/UV. Izbrali smo tri barvila, ki se pogosto uporabljajo v tekstilni industriji, in sicer C. I. Acid Red 374, C. I. Reactive Black 5 in C. I. Direct Red 80. Proučili smo vpliv moči UV-sevanja na samo hitrost in učinkovitost razgradnje barvil ter spremljali spremembe parametrov onesnaženja.
Ključne besede: napredni oksidacijski postopek, vodikov peroksid, razbarvanje, C. I. Acid Red 374, C. I. Reactive Black 5, C. I. Direct Red 80
Objavljeno: 06.05.2019; Ogledov: 376; Prenosov: 53
.pdf Celotno besedilo (2,41 MB)

Cross-linked porous poly(acrylic acid-co-acrylamide) from high internal phase emulsions: preparation and functionalisation
Janja Majer, Peter Krajnc, 2009, izvirni znanstveni članek

Opis: By using emulsions with high volume fractions of internal phase as polymerisation media porous copolymers of acrylic acid and acrylamide, cross-linked by methylenebisacrylamide, were prepared. The ratio of acrylic acid to acrylamide were varied (molar ratios 70:30, 50:50, 30:70) in order to yield polymers with various loading of acidic functional groups. Porous polymers with an open-cellular architecture were obtained with void diameters between 2.8 μm and 3.9 μm and with interconnecting pores approx. 0.3 μm in diameter. The chemical composition of the polymers influenced the conversion degrees during the process of functionalisation of acidic groups to acid chloride, being the highest in the case of polymer with the lowest content of acrilyc acid.
Ključne besede: porous monoliths, copolymers, polyacrylic acid, polyacrylamide, plyHIPE, high internal phase emulsion
Objavljeno: 17.08.2017; Ogledov: 1067; Prenosov: 97
.pdf Celotno besedilo (218,85 KB)
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Combating Varroa destructor in honeybee colonies using flumethrin or fluvalinate
Aleš Gregorc, Maja Ivana Smodiš Škerl, 2007, izvirni znanstveni članek

Opis: Mite mortality in two apiaries, one with 32 and the other with 15 honeybee (Apis mellifera carnica) colonies, was recorded prior to and after flumethrin or fluvalinate treatments and after a control, oxalic-acid application. During the 42- and 51-day pre-treatment periods, the average daily natural mite drop was 0.04 (± 0.04) and 2.82 (± 2.19), respectively, which represents 1.09% (± 1.06) and 3.84% (± 3.04) of the total number of mites found during the experiment. The flumethrin or fluvalinate applications resulted in an average mite mortality at the two apiaries of 214.46 (± 260.02) and 4,098.64 (± 2,508.31). The treatments resulted in a 19.11% (± 14.62) and a 39.28% (± 10.47) reduction in the number of mites in slightly infested colonies and 94.30% (± 4.26) and 96.24% (± 3.14) in highly infested colonies. The difference in treatment efficacy between both apiaries was significant (P < 0.001) and indicates that fluvalinate and flumethrin are highly efficacious in dealing with highly infested honeybee colonies with sealed brood. The importance of effective mite control in colonies with a high level of natural mite mortality is discussed in this study.
Ključne besede: Acaricides, control methods, Apis mellifera, oxalic acid, mite infestation
Objavljeno: 04.08.2017; Ogledov: 1337; Prenosov: 262
.pdf Celotno besedilo (149,12 KB)
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Influence of the temperature on the efficiency of cellulose treatment using copolymer chitosan-eugenol
Olivera Šauperl, Jasna Tompa, Julija Volmajer Valh, 2014, izvirni znanstveni članek

Opis: In order to achieve effective antimicrobial protection of textile materials against microorganisms, a natural compound called chitosan has become very interesting. In regard to the antimicrobial protection of textile materials, functionalization with chitosan does not affect some other properties, such as anti-oxidative or any other action. For this reason, it seems appropriate for chitosan to be combined with any natural antimicrobial active compound, such as eugenol, an extract of clove oil. During this research viscose as a representative of cellulose fibers was used, because it can be functionalized relatively easily. In terms of functionalization, the drying temperature of viscose, after antimicrobial compound application onto substrate, as well as the successful synthesis of copolymer chitosan/eugenol is also important. FTIR spectroscopy was used to evaluate the efficiency of synthesizing a chitosan/eugenol graft copolymer. The spectrophotometric method Acid Orange 7 was chosen as a means for determining the proportion of available antimicrobial active amino groups. In addition, microbiological testing of selected pathogenic micro-organisms was also performed. The results were compared with the results for viscose functionalized by a 1% solution of chitosan.
Ključne besede: chitosan, eugenol, functionalization, viscose, FTIR spectroscopy, Acid orange 7, antimicrobial
Objavljeno: 02.08.2017; Ogledov: 543; Prenosov: 328
.pdf Celotno besedilo (233,00 KB)
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Comparison of cultivable acetic acid bacterial microbiota in organic and conventional apple cider vinegar
Aleksandra Mori Štornik, Barbara Skok, Janja Trček, 2016, izvirni znanstveni članek

Opis: Organic apple cider vinegar is produced from apples that go through very restricted treatment in orchard. During the first stage of the process, the sugars from apples are fermented by yeasts to cider. The produced ethanol is used as a substrate by acetic acid bacteria in a second separated bioprocess. In both, the organic and conventional apple cider vinegars the ethanol oxidation to acetic acid is initiated by native microbiota that survived alcohol fermentation. We compared the cultivable acetic acid bacterial microbiota in the production of organic and conventional apple cider vinegars from a smoothly running oxidation cycle of a submerged industrial process. In this way we isolated and characterized 96 bacteria from organic and 72 bacteria from conventional apple cider vinegar. Using the restriction analysis of the PCR-amplified 16S-23S rRNA gene ITS regions, we identified four different HaeIII and five different HpaII restriction profiles for bacterial isolates from organic apple cider vinegar. Each type of restriction profile was further analyzed by sequence analysis of the 16S-23S rRNA gene ITS regions, resulting in identification of the following species: Acetobacter pasteurianus (71.90 %), Acetobacter ghanensis (12.50 %), Komagataeibacter oboediens (9.35 %) and Komagataeibacter saccharivorans (6.25 %). Using the same analytical approach in conventional apple cider vinegar, we identified only two different HaeIII and two different HpaII restriction profiles of the 16S‒23S rRNA gene ITS regions, which belong to the species Acetobacter pasteurianus (66.70 %) and Komagataeibacter oboediens (33.30 %). Yeasts that are able to resist 30 g/L of acetic acid were isolated from the acetic acid production phase and further identified by sequence analysis of the ITS1-5.8S rDNA‒ITS2 region as Candida ethanolica, Pichia membranifaciens and Saccharomycodes ludwigii. This study has shown for the first time that the bacterial microbiota for the industrial production of organic apple cider vinegar is clearly more heterogeneous than the bacterial microbiota for the industrial production of conventional apple cider vinegar. Further chemical analysis should reveal if a difference in microbiota composition influences the quality of different types of apple cider vinegar.
Ključne besede: microbiology, acetic acid bacteria, apple cider vinegar
Objavljeno: 24.07.2017; Ogledov: 10368; Prenosov: 116
.pdf Celotno besedilo (289,47 KB)
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16S rRNA in situ hybridization followed by flow cytometry for rapid identification of acetic acid bacteria involved in submerged industrial vinegar production
Janja Trček, Luka Lipoglavšek, Gorazd Avguštin, 2016, izvirni znanstveni članek

Opis: Acetic acid bacteria are involved in many biotechnological processes such as vitamin C, gluconic acid, miglitol or acetic acid production, and others. For a technologist trying to control the industrial process, the ability to follow the microbiological development of the process is thus of importance. During the past few years hybridization in a combination with flow cytometry has oft en been used for this purpose. Since vinegar is a liquid, it is an ideal matrix for flow cytometry analysis. In this work we have constructed a specific probe for highly acetic acid-resistant species of the acetic acid bacteria and a protocol for in situ hybridization, which in combination with flow cytometry enables direct monitoring of bacteria producing vinegar with >10 % of acetic acid. The approach was successfully applied for monitoring microbiota during industrial vinegar production.
Ključne besede: microbiology, acetic acid bacteria, flow cytometry
Objavljeno: 24.07.2017; Ogledov: 26967; Prenosov: 289
.pdf Celotno besedilo (500,81 KB)
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The influence of $Ce^{3+}$ ions on the corrosion rate of stainless steel in acidic solutions of different pH-values
Aljana Petek, Sebastijan Kovačič, 2014, izvirni znanstveni članek

Opis: The corrosion resistance of AISI 420 stainless steel in 0.1 mol $L^{−1}$ $H_2SO_4$ + 0.1 mol $L^{−1}$ $Na_2SO_4$ solutions at different pH-values and the inhibiting effect of $Ce^{3+}$ ions was studied using electrochemical polarization methods. The results reveal decreasing of the corrosion rate with an increasing the pH of the solution, which demonstrates the progressive protective character of the inhibitor used. At pH lower than 3.33, the corrosion inhibition was most probably a result of the competitive adsorption of $Ce^{3+}$ with $H^+$ ions on the cathodic sites of the electrode surface, and it was found to be dependent on the relative concentration of $H^+$/$Ce^{3+}$. The peroxide generated from the oxygen reduction reaction at pH 3.33 was found to be capable oxidize trivalent cerium (Ce) to the tetravalent state. As obtained hydroxide precipitates act as diffusion barrier hindering the corrosion processes, whereafter a spontaneous passivity occurs on the steel surface at this pH.
Ključne besede: acid corrosion, green corrosion inhibitor, stainless steel, electrochemical techniques
Objavljeno: 24.07.2017; Ogledov: 612; Prenosov: 259
.pdf Celotno besedilo (463,32 KB)
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Phase equilibrium measurements and data correlation for the ternary system oleic acid + 1-octanol + carbon dioxide
Chiara Giulia Laudani, Mateja Primožič, Željko Knez, Maja Leitgeb, 2009, izvirni znanstveni članek

Opis: A study of the high-pressure phase equilibria in the ternary system oleic acid/1- octanol/supercritical CO2 was performed to obtain information for optimization of enzymatic synthesis of n-octyl oleate. Equilibrium data were measured at temperatures of 308.15, 323.15 and 343.15 K over a pressure range from 1 to 25 MPa. Two different apparatuses: a Variable Volume View Cell and a Batch Stirred Tank were used employing synthetic and static-analytic measurement methods, respectively. The measured solubility of dense CO2 in the binary liquid mixture oleic acid/1-octanol covered the range from 0.0781 to 0.7686 of CO2 molar fraction. CO2 solubility increased with increasing pressure up to 10 MPa. At higher pressures, no significant increase was observed. The Soave-Redlich-Kwong equation-of-state (SRK-EoS) with quadratic mixing rules was successfully used for data correlation in the whole P-T-x region studied.
Ključne besede: data correlation, 1-octanol, oleic acid, supercritical carbon dioxide, Soave-Redlich-Kwong equation-of-state, vapor-liquid equilibria
Objavljeno: 05.07.2017; Ogledov: 716; Prenosov: 73
.pdf Celotno besedilo (3,35 MB)
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Microorganisms with claimed probiotic properties: an overview of recent literature
Sabina Fijan, 2014, pregledni znanstveni članek

Opis: Probiotics are defined as live microorganisms, which when administered in adequate amounts, confer a health benefit on the host. Health benefits have mainly been demonstrated for specific probiotic strains of the following genera: Lactobacillus, Bifidobacterium, Saccharomyces, Enterococcus, Streptococcus, Pediococcus, Leuconostoc, Bacillus, Escherichia coli. The human microbiota is getting a lot of attention today and research has already demonstrated that alteration of this microbiota may have far-reaching consequences. One of the possible routes for correcting dysbiosis is by consuming probiotics. The credibility of specific health claims of probiotics and their safety must be established through science-based clinical studies. This overview summarizes the most commonly used probiotic microorganisms and their demonstrated health claims. As probiotic properties have been shown to be strain specific, accurate identification of particular strains is also very important. On the other hand, it is also demonstrated that the use of various probiotics for immunocompromised patients or patients with a leaky gut has also yielded infections, sepsis, fungemia, bacteraemia. Although the vast majority of probiotics that are used today are generally regarded as safe and beneficial for healthy individuals, caution in selecting and monitoring of probiotics for patients is needed and complete consideration of risk-benefit ratio before prescribing is recommended.
Ključne besede: Lactic-acid bacteria, Lactobacillus, Bifidobacterium, Saccharomyces, Enterococcus, Streptococcus, Pediococcus, Leuconostoc, Bacillus, Escherichia coli
Objavljeno: 21.06.2017; Ogledov: 790; Prenosov: 314
.pdf Celotno besedilo (267,98 KB)
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The influence of royal jelly and human interferon-alpha (HuIFN-[alpha]N3) on proliferation, glutathione level and lipid peroxidation in human colorectal adenocarcinoma cells in vitro
Bratko Filipič, Lidija Gradišnik, Klemen Rihar, Eugen Šooš, Adriana Pereyra Gonzales, Jana Potokar, 2015, izvirni znanstveni članek

Opis: Among royal jelly’s (RJ) various biological activities, its possible antitumour activity deserves particular attention. The purpose of this study was to investigate the influence of RJ, its bioactive component 10-hydroxy-2-decenoic acid (10- HDA), and human interferon-alpha (HuIFN-αN3) on the proliferation of human colorectal adenocarcinoma cells (CaCo- 2), and ascertain their effect on intracellular glutathione (GSH) level and lipid peroxidation. We studied the antiproliferative (AP) activity of RJ [(0.1 g/10 mL phosphate buffer saline (PBS)], HuIFN-αN3 (1000 I.U. mL-1), 10-HDA at 100.0 μmol L-1, and their different combinations, in the ratio 1:1, 1:2, and 2:1 on CaCo-2 cells. The GSH level was measured by glutathione assay. The lipid peroxidation was measured by malondialdehyde (MDA) assay. Single RJ had a low AP activity: 2.0 (0.5 mg mL-1). HuIFN-αN3 had an AP activity of 2.5 (208.33 I.U. mL-1), while 10-HDA had an AP activity of 1.5 (37.5 μmol mL-1). The highest AP activity of 3.8 was obtained when RJ and HuIFN-αN3 were applied at the ratio 2:1. In that combination the level of GSH was 24.9±2.4 nmol g-3 of proteins (vs. 70.2±3.2 nmol g-3 in the control) and the level of MDA was 72.3±3.1 nmol g-3 (vs. 23.6±9.1 nmol g-3 in the control). It is generally assumed that 10-HDA, an important constituent of RJ, together with HuIFN-αN3, is responsible for the inhibition of CaCo-2 cells proliferation in vitro. In our study, however, RJ and HuIFN-αN3 applied at 2:1 decreased the level of GSH the most and significantly increased lipid peroxidation via MDA in CaCo-2 cells. Future studies should show whether these GSH- and MDA-related activities of RJ, HuIFN-αN3, 10-HDA, and their combinations may decrease the tumorigenicity index and tumorigenic potential of various tumour cells in vitro.
Ključne besede: antiproliferative activity, antitumour activity, malondialddehyde, CaCo-2 cells, 10-hydroxy-2-decenoic acid
Objavljeno: 30.03.2017; Ogledov: 616; Prenosov: 72
.pdf Celotno besedilo (355,56 KB)
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