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1.
The effect of supplementing pig diet with chestnut wood extract or hops on fresh meat and dry-cured products
Urška Tomažin, Martin Škrlep, Maja Prevolnik Povše, Nina Batorek Lukač, Danijel Karolyi, Matjaž Červek, Marjeta Čandek-Potokar, 2020, original scientific article

Abstract: Oxidation is one of the major reasons for impaired quality of meat and meat products but can be prevented by the addition of antioxidants. In the present study, the effect of dietary sweet chestnut wood extract and hop cones on the quality and oxidative stability of meat and dry-cured products was investigated. Control pigs (N = 11) were fed a commercial diet (13.1 MJ metabolizable energy, 15.5% crude protein), while the other two experimental groups were supplemented with 3% of sweet chestnut wood extract (Tannin; N = 12) or 0.4% of hop cones (Hops; N = 11). The quality of meat and dry-cured products was evaluated by means of chemical composition, water holding capacity, objective color, and lipid and protein oxidation. No major effects of sweet chestnut wood extract or of hops supplementation were observed, nevertheless, some indications of improved water holding capacity could be attributed to antioxidants supplementation. The color evolution of dry-cured bellies from Tannin and Hops groups of pigs during refrigerated storage was also indicative of an improved oxidative stability.
Keywords: pig meat, meat quality, pig diet, tannin extract, hops, dry-cured products, oxidation, pigs
Published in DKUM: 23.12.2024; Views: 0; Downloads: 3
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2.
Chemical binding of chitosan and chitosan nanoparticles onto oxidized cellulose
Olivera Šauperl, Mirjana Kostić, Jovana Milanovic, Lidija Fras Zemljič, 2015, original scientific article

Abstract: The aim of this study was to analyze binding of chitosan and chitosan nanoparticles onto cellulose via oxidized cellulose. The ability of chitosan and chitosan nanoparticles to be adsorbed onto surfaces was determined by the use of the XPS spectroscopy which provided information about chemical composition of the fiber surface. On the other hand, the gravimetric method was also used by which the amount of chitosan and chitosan nanoparticles bounded onto surface was calculated based on the difference in masses before and after functionalization. The most important was to study the influence of aldehyde groups on the stability of chitosan binding onto cellulose. Thus, desorption of chitosan/chitosan nanoparticles from the fiber surfaces was evaluated by the presence of total nitrogen (TN) in desorption bath as well as by polyelectrolyte titrations. Together with these two methods, desorption was evaluated also by gravimetric method, where the extent of desorption was evaluated on the basis of the differences in the masses of fibers before and after desorption. It is concluded that the chitosan and chitosan nanoparticles are more efficiently bounded onto oxidized cellulose in comparison with the non-oxidized (reference) ones. Despite the binding of the positively-charged amino groups with the negative groups of cellulose and consequently smaller amount of available/residual protonated amino groups that are responsible for bioactivity, such functionalized fibers are still specifically antimicrobial.
Keywords: cellulose, oxidized cellulose, oxidation, chitosan, chitosan nanoparticles, FTIR, XPS, antimicrobial functionalization
Published in DKUM: 02.08.2017; Views: 1416; Downloads: 499
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3.
Microstructure analysis of internally oxidized Cu-C composite
Rebeka Rudolf, Ladislav Kosec, Alojz Križman, Ivan Anžel, 2006, original scientific article

Abstract: On the basis of experimentally obtained data, it was established that submicron-size bubbles are formed by the internal oxidation of Cu-C composite with fine dispersed graphite particles. They are homogeneously distributed in the Cu-matrix. This process starts with the dissolution of oxygen into the metal at the free surfaces, and continues with the diffusion of oxygen atoms into the volume of copper crystal lattice where they react with the graphite particles. The reactions of dissolved oxygen with carbon yield the gas products (CO2, CO), which cannot be dissolved in the crystal lattice of the matrix. The gas molecules, which are enclosed in the space previously occupied by the graphite, have a greater specific volume than the solid graphite. Consequently, compressive stresses arise in the copper matrix around the bubbles. The interaction of these stress fields with gliding dislocations during loading could improve the mechanical properties of the copper. The internal oxidation kinetic in Cu-C composite depends on the diffusion of oxygen in the copper matrix, and the penetration depth of the internal oxidation front indicates the parabolic nature of the process.
Keywords: metallurgy, Cu-C composites, internal oxidation, bubbles
Published in DKUM: 03.07.2017; Views: 1180; Downloads: 97
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4.
Internal oxidation of silver alloys with tellurium, selenium and sulphur
Gorazd Kosec, Ladislav Kosec, Ivan Anžel, Vasilij Gontarev, Borut Kosec, Milan Bizjak, 2005, original scientific article

Abstract: Silver alloys with tellurium, selenium and sulphur fulfil the conditions for the internal oxidation. Microstructure of these alloys consists of matrix (dilute solid solution) and particles of intermetallic compounds. Internal oxidation of ternary alloys is very similar to that of the binary alloys, but there are also distinctions in thermodynamics properties of alloying elements. At the direct oxidation of the particles of the intermetallic compound the phenomena of the selective oxidation was observed. Concentration of more reactive elements is increasing in the oxidized part of the particles of the intermetallic compound (Te in AgTeSe alloys). Therefore the precipitated oxides formed with diffusional internal oxidation are richer with less reactive alloying element (Se in AgTeSe alloy). In the precipitated oxide particles the concentration of selenium is more than twice higher than of tellurium.
Keywords: internal oxidation, silver, alloys, compound, particle
Published in DKUM: 03.07.2017; Views: 1135; Downloads: 103
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5.
Pressing of partially oxide-dispersion-strengthened Copper using the ECAP process
Matija Kos, Janko Ferčec, Mihael Brunčko, Rebeka Rudolf, Ivan Anžel, 2014, original scientific article

Abstract: A combination of internal oxidation (IO) and equal channel angular pressing (ECAP) was used to explore the possibility of uniting the mechanisms of dispersion and deformation strengthening to improve the properties of a Cu-Al alloy with 0.4 % Al. The IO of Cu-Al billets served in the first step of the experiment as a means for dispersion, strengthening the mantle of the billets with a fine dispersion of nanosized oxide particles. The experimental procedure continued with deformation strengthening performed by ECAP, which allowed an intense plastic strain through simple shear. Material flow in a partly internally oxidized Cu-0.4 % Al billet and in a homogenous reference sample made of modelling mass was also studied to analyse, on the macroscale, the influence of the internal oxidation zone (IOZ) on the material flow behaviour during the ECAP process. The analysis was performed with the aim of revealing the uniformity of the strain distribution and to obtain information about the deformation strengthening across the volume of the billet. We found that the oxide particles have a minor influence on the material flow on the macroscopic scale during the ECAP process. However, the degree of deformation strengthening in the IOZ was much lower than in the unoxidized core region. The combination of IO and ECAP allows us to produce a Cu composite composed of a hardened oxidized mantle region with good electrical and thermal conductivity and a high- hardened core region. This combination represents a new technological route for the production of high-hardness Cu composites, which could also be used at higher temperatures.
Keywords: ECAP, Cu-Al alloys, strengthening mechanisms, internal oxidation
Published in DKUM: 17.03.2017; Views: 1469; Downloads: 98
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6.
The applicability of an advanced oxidation process for textile finishing wastestreams & fate of persistent organic pollutants
Julija Volmajer Valh, Alenka Majcen Le Marechal, Boštjan Križanec, Simona Vajnhandl, 2012, original scientific article

Abstract: The trend of sustainable use of available water resources encourages textile finishing enterprises to implement efficient wastewater treatment technologies that enable water recycling, and not just itćs discharging into the local wastewater treatment plants (WWTP). This paper presents the results obtained from the H2O2/UV treatment of wastewater from Slovene textile finishing company. Laboratory scale decolouration experiments were performed on the most representative wastewater samples, collected in three months period. In general 80 % decolouration and 86 % total organic carbon (TOC) reduction was achieved. On the other hand, the use of ultraviolet (UV) radiation to degrade and destroy organic pollutants in textile wastewater could lead to the formation of toxic dioxins and dioxin-like compounds, groups of persistent organic pollutants, especially due to the presence of halogenated compounds in textile finishing processes. For these reasons, textile wastewater samples were analysed for any content of dioxins before and after the treatment with H2O2/UV.
Keywords: tekstilne odpadne vode, napredni oksidacijski procesi, H2O2/UV, dioksini, textile wastewater, advanced oxidation processes, H2O2/UV, ecological parameters, dioxins
Published in DKUM: 10.07.2015; Views: 2086; Downloads: 47
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7.
Reactive dye decolorization using combined ultrasound/H2O2
Darinka Brodnjak-Vončina, Alenka Majcen Le Marechal, 2003, original scientific article

Abstract: The decolorization of six vinylsulphone reactive dyes (C.I. Reactive Yellow 15, C.I. Reactive Red 22, C.I. Reactive Blue 28, Remazol Dark Black N 150%, C.I. Reactive Blue 220 and C.I. Reactive Black 5) in aqueous solution was investigated using ultrasound and ultrasoundž hydrogen peroxide degradation. Two different concentration levels of hydrogen peroxide were used. The efficiency of the decolorization was evaluated by measuring the absorbance of the dye solutions. The results show that ultrasound treatment was significantly enhanced in the presence of H2O2.
Keywords: ultrasonic irradiation, decolorization, oxidation processes, hydrogen peroxide, reactive dyes, vinylsulphone reactive dyes
Published in DKUM: 01.06.2012; Views: 2377; Downloads: 101
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8.
Crystal-structure and Mössbauer studies of Li[sub]1.746]Nd[sub]4.494FeO9[sub]9.493
Mihael Drofenik, Irena Ban, Darko Makovec, Darko Hanžel, Amalija Golobič, Ljubo Golič, 2007, original scientific article

Abstract: The ▫$Li_1.746Nd_4.494FeO_9.493$▫ (LNF) ternary phase, located in the ▫$Li_2O$▫-rich part of the ▫$Li_2O-Nd_2O_3-Fe_2O_3$▫ system, crystallizes with a cubic unit cell of dimension and the space group Im3m. Refinement on F resulted in R=1.9%. The structure is comprised of a network of corners, edges and faces sharing the coordination polyhedra of neodymium. In between this skeleton the regular octahedra of oxygen-coordinated iron and trigonal prisms of lithium are located. The Mössbauer spectra revealed the presence of ▫$Fe^3+$▫, ▫$Fe^4+$▫ and ▫$Fe^5+$▫ ions distributed on two symmetry-independent lattice positions.
Keywords: crystal structure, ternary compounds, single-crystal X-ray diffraction, Mössbauer spectroscopy, iron oxidation state, kristalna struktura, ternarne spojine, rentgenska difrakcija, Mössbauerjeva spektroskopija, rentgenska strukturna analiza
Published in DKUM: 01.06.2012; Views: 2701; Downloads: 47
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9.
In-situ monitoring of internal oxidation of dillute alloys
Mihael Brunčko, Ivan Anžel, Albert C. Kneissl, 2007, original scientific article

Abstract: This paper presents a non-destructive measurement method that enables identification and characterization of phenomena during internal oxidation of metallic materials as well as monitoring the kinetics of internal oxidation using "in-situ" electrical resistance measurements. A special laboratory device, based on the unique measurement cell, for the electrical resistance measurements at high temperatures and the model for electrical resistance transformation into an instantaneous microstructure were developed. To accomplish this, the process of internal oxidation was divided into the sequence of the key partial reactions that were presented in the model as the parallel andžor serial connected time variable resistors in the electrical circuit. The validity of the transformation model was experimentally confirmedby internal oxidation of Ag-Sn (2 at.% Sn) alloy at different oxidation temperatures in air atmosphere. The comparison of the results obtained by "in-situ" electrical resistance measurements with those obtained by metallographic analysis and Wagnerćs theory shows that the novel method presents a more effective tool for monitoring of internal oxidation kinetics. The method identifies also the microstructural defects and their influences onthe kinetics of internal oxidation.
Keywords: metallurgy, Ag-Sn alloy, internal oxidation, electrical resistance
Published in DKUM: 01.06.2012; Views: 1834; Downloads: 43
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10.
Ecological alternatives to the reduction and oxidation processes in dyeing with vat and sulphur dyes
Mojca Božič, Vanja Kokol, 2008, review article

Abstract: This article gives a summary of the most commonly used ecologically unfriendly processes for the reduction and oxidation of vat and sulphur dyes. It also describes the new alternatives that are in the development stage and could be important in the near future. Sodium dithionite as the dominant reducing agent produces large amounts of sodium sulphate, and also toxic sulphite and thiosulphate as by-products. Consequently, high amounts of hydrogen peroxide and alkali are required for the treatment of effluents, which add to the cost of the process. Attempts have been made to use organic biodegradable reducing agents, enzymes, catalytic hydrogenation, and also indirect or direct, electrochemical reductive methods that employ a redox mediator (electron-carrier). The reduction has also been carried out via the dye radical molecule or, in the case of indigo, by direct electrochemical reduction using graphite as the electrode material. Physical techniques, for example using ultrasound, magnetic fields or UV have been shown to be effective only when used to accelerate methods using classical reduction and oxidation processes. However, although these methods offer some environmental benefits, there is still no satisfactory alternative reducing and/or oxidising agent available today.
Keywords: textile dyeing, vat dyes, sulphur dyes, reduction, oxidation, catalysis, ecology, organic agents, electrochemistry, ultrasound, magnetic field, UV application, biotechnology
Published in DKUM: 01.06.2012; Views: 3143; Downloads: 120
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