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1.
Barvanje povezav grafa z najmanjšim številom palet : na študijskem programu Izobraževalna matematika in izobraževalno računalništvo
Karmen Bregač, 2023, magistrsko delo

Opis: V magistrskem delu obravnavamo paletno barvanje povezav in paletni indeks različnih družin grafov. Dobro barvanje povezav je barvanje, pri katerem velja, da nobeni incidenčni povezavi nista pobarvani z enako barvo. Dobro barvanje povezav grafa za vsako vozlišče definira množico barv incidenčnih povezav. Takšno množico imenujemo paleta vozlišča. V literaturi se avtorji večinoma osredotočajo na barvanje povezav grafov, pri katerem je uporabljeno največje možno število palet. Mi se bomo osredotočili na iskanje takšnega barvanja povezav grafa, za katerega bo veljalo, da je barvanje dobro in pri katerem bo uporabljeno najmanjše možno število palet, ki ga imenujemo paletni indeks grafa. Na začetku spoznamo osnove teorije grafov, ki nam pomagajo pri nadaljnjem razumevanju teorije. V osrednjem delu magistrske dela ugotovimo, da nas dobro barvanje z najmanjšim številom možnih barv ne pripelje vedno do najmanjšega števila palet. Spoznamo tudi, kako poiskati paletne indekse nekaterih znanih družin grafov in posebnih primerov grafov, pri katerih namesto minimalnega barvanja povezav uporabimo barvanje z večjim številom barv.
Ključne besede: Barvanje povezav, paletno barvanje povezav, paletni indeks.
Objavljeno v DKUM: 07.09.2023; Ogledov: 224; Prenosov: 9
.pdf Celotno besedilo (5,34 MB)

2.
Two-layer functional coatings of chitosan particles with embedded catechin and pomegranate extracts for potential active packaging
Sanja Potrč, Tjaša Kraševac Glaser, Alenka Vesel, Nataša Poklar Ulrih, Lidija Fras Zemljič, 2020, izvirni znanstveni članek

Opis: Two-layer functional coatings for polyethylene (PE) and polypropylene (PP) films were developed for the active packaging concept. Prior to coating, the polymer films were activated by O$_2$ and NH$_3$ plasma to increase their surface free energy and to improve the binding capacity and stability of the coatings. The first layer was prepared from a macromolecular chitosan solution, while the second (upper) layer contained chitosan particles with embedded catechin or pomegranate extract. Functionalized films were analyzed physico-chemically to elemental composition using ATR-FTIR spectroscopy and XPS. Further, oxygen permeability and wettability (Contact Angle) were examined. The antimicrobial properties were analyzed by the standard ISO 22196 method, while the antioxidative properties were determined with an ABTS assay. Functionalized films show excellent antioxidative and antimicrobial efficacy. A huge decrease in oxygen permeability was achieved in addition. Moreover, a desorption experiment was also performed, confirming that the migration profile of a compound from the surfaces was in accordance with the required overall migration limit. All these properties indicate the great potential of the developed active films/foils for end-uses in food packaging.
Ključne besede: plazma, citozan, polifenoli, aktivno pakiranje, plasma, chitosan, polyphenols, coating, active package
Objavljeno v DKUM: 12.07.2023; Ogledov: 362; Prenosov: 22
.pdf Celotno besedilo (2,70 MB)
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3.
The psychodynamic processes related to the involvement in peacekeeping missions : experiences of Slovenian police officers
Branko Lobnikar, Špela Vesel, Emanuel Banutai, 2011, izvirni znanstveni članek

Opis: Purpose: The purpose of this paper is to review the decade of Slovenian police officer’s experiences with international peacekeeping operations. The main goal of police officers, involved in these missions, is to prevent conflicts between opposite sites, to implement basic agreements, protect humanitarian missions and reinforce policing operations in the conflict area. The purpose of the paper is to acknowledge the lessons learned while planning and implementing further cooperation of Slovenian police officers in peacekeeping (police) operations. The main purpose of the paper is to analyze the consequences of deployment to peacekeeping missions for police officers as well as their family members (partners and children) by analyzing the psychodynamic processes related to the involvement in peacekeeping missions. Design/Methods/Approach: The paper is based on the review of literature. The empirical part of the paper presents the results of the research on a small sample of police officers (n = 36) and their family members (n = 25 partners + 35 children). Findings: Police peacekeepers should be well prepared for different stress situations; they are exposed to various stress factors before, during, and after serving in a mission. That is why training and reintegration programmes are of great importance. We establish that respondents assess that deployment to a peacekeeping mission has a positive and negative impact on the relationships between family members. As many as ¾ of mission members believe deployment can have a positive impact above all in the sense of strengthening the emotional ties between partners, increased mutual trust and strengthening of the partnership. For them, deployment to a peacekeeping mission is a challenge and personal experience, which can change the way they see the world. 2/3 of partners state similar positive impacts and they also believe that there is more trust between the partners after the experience with the peacekeeping mission, they treasure their time together and thus represent bigger support for each other in difficult times. As the most common problem, respondents perceived marital problems and the occurrence of negative feelings among family members (anger, avoidance, judgment ...). A large share of respondents stressed problems with children. 43.8% of respondents also named depression as a problem. Research limitations/implications: The findings are limited to the Slovenian police and their police officer’s experiences, serving in various police peacekeeping missions and their family members. Practical implications: Based on lessons learned this paper complements the results of different surveys of the researched topic. The results cannot be completely generalized, although some findings could also be useful to similar police organizations in Europe. Originality/Value: This paper addresses and explores different small scale surveys, conducted on sampled Slovenian police officers who served in peacekeeping missions and their family members. Findings could be of interest for the general as well as expert audience.
Ključne besede: police, police officer’s family, peacekeeping missions, Slovenia, stress, training and reintegration programmes, SE Europe
Objavljeno v DKUM: 05.05.2020; Ogledov: 1036; Prenosov: 53
.pdf Celotno besedilo (624,54 KB)
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4.
(d, n)-pakirno barvanje za posplošene grafe Sierpińskega : magistrsko delo
Anže Jeromel, 2019, magistrsko delo

Opis: V magistrski nalogi so opisani grafi Sierpińskega in njihove posplošitve, (d, n)-pakirno barvanje grafov ter računsko iskanje (d, n)-pakirnih kromatičnih števil. Razvili smo algoritem za generiranje grafov Sierpińskega z osnovo 4 ter implementirali štiri metode barvanja grafov. Našli smo točna (d, n)-pakirna kromatična števila za različne kombinacije (d, n) pri grafih stopnje 2, pri grafih višjih stopenj pa njihove zgornje meje. Prav tako smo našli točna (1, 1)-pakirna kromatična števila dveh izbranih posplošenih grafov Sierpińskega do vključno stopnje 5.
Ključne besede: Sierpiński, pakirno barvanje, pakirno kromatično število
Objavljeno v DKUM: 04.06.2019; Ogledov: 1249; Prenosov: 110
.pdf Celotno besedilo (4,27 MB)

5.
Linear recognition of generalized Fibonacci cubes $Q_h (111)$
Yoomi Rho, Aleksander Vesel, 2016, izvirni znanstveni članek

Opis: The generalized Fibonacci cube $Q_h(f)$ is the graph obtained from the $h$-cube $Q_h$ by removing all vertices that contain a given binary string $f$ as a substring. In particular, the vertex set of the 3rd order generalized Fibonacci cube $Q_h(111)$ is the set of all binary strings $b_1b_2 ... b_h$ containing no three consecutive 1’s. We present a new characterization of the 3rd order generalized Fibonacci cubes based on their recursive structure. The characterization is the basis for an algorithm which recognizes these graphs in linear time.
Ključne besede: graph theory, Fibonacci cubes, recognition algorithm
Objavljeno v DKUM: 10.07.2017; Ogledov: 1138; Prenosov: 170
.pdf Celotno besedilo (803,81 KB)
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6.
Protein adsorption on various plasma-treated polyethylene-terephthalate substrates
Nina Recek, Morana Jaganjac, Metod Kolar, Lidija Milković, Miran Mozetič, Karin Stana-Kleinschek, Alenka Vesel, 2013, izvirni znanstveni članek

Opis: Protein adhesion and cell response to plasma-treated polymer surfaces were studied. The polymer polyethylene terephthalate (PET) was treated in either an oxygen plasma to make the surface hydrophilic, or a tetrafluoromethane CF4 plasma to make the surface hydrophobic. The plasma source was radiofrequency (RF) discharge. The adsorption of albumin and other proteins from a cell-culture medium onto these surfaces was studied using a quartz crystal microbalance (QCM), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The cellular response to plasma-treated surfaces was studied as well using an MTT assay and scanning electron microscopy (SEM). The fastest adsorption rate was found on the hydrophilic oxygen plasma-treated sample, and the lowest was found on the pristine untreated sample. Additionally, the amount of adsorbed proteins was higher for the oxygen-plasma-treated surface, and the adsorbed layer was more viscoelastic. In addition, cell adhesion studies support this finding because the best cell adhesion was observed on oxygen-plasma-treated substrates.
Ključne besede: oxygen and fluorine plasma treatment, polymer surface modification, protein adsorption, cell adhesion, quartz crystal microbalance, QCM
Objavljeno v DKUM: 22.06.2017; Ogledov: 1131; Prenosov: 413
.pdf Celotno besedilo (2,39 MB)
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7.
Covalent binding of heparin to functionalized PET materials for improved haemocompatibility
Metod Kolar, Miran Mozetič, Karin Stana-Kleinschek, Mirjam Fröhlich, Boris Turk, Alenka Vesel, 2015, izvirni znanstveni članek

Opis: The hemocompatibility of vascular grafts made from poly(ethylene terephthalate) (PET) is insufficient due to the rapid adhesion and activation of blood platelets that occur upon incubation with whole blood. PET polymer was treated with NHx radicals created by passing ammonia through gaseous plasma formed by a microwave discharge, which allowed for functionalization with amino groups. X-ray photoelectron spectroscopy characterization using derivatization with 4-chlorobenzaldehyde indicated that approximately 4% of the –NH2 groups were associated with the PET surface after treatment with the gaseous radicals. The functionalized polymers were coated with an ultra-thin layer of heparin and incubated with fresh blood. The free-hemoglobin technique, which is based on the haemolysis of erythrocytes, indicated improved hemocompatibility, which was confirmed by imaging the samples using confocal optical microscopy. A significant decrease in number of adhered platelets was observed on such samples. Proliferation of both human umbilical vein endothelial cells and human microvascular endothelial cells was enhanced on treated polymers, especially after a few hours of cell seeding. Thus, the technique represents a promising substitute for wet-chemical modification of PET materials prior to coating with heparin.
Ključne besede: poly(ethylene terephthalate), vascular graft, biocompatibility, heparin, plasma, functionalization, haemolysis, platelet adhesion, endothelization
Objavljeno v DKUM: 21.06.2017; Ogledov: 1161; Prenosov: 339
.pdf Celotno besedilo (1,70 MB)
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8.
L(2,1)-labeling of the strong product of paths and cycles
Zehui Shao, Aleksander Vesel, 2014, izvirni znanstveni članek

Opis: An L(2,1)-labeling of a graph G = (V, E) is a function f from the vertex set V(G) to the set of nonnegative integers such that the labels on adjacent vertices differ by at least two and the labels on vertices at distance two differ by at least one. The span of f is the difference between the largest and the smallest numbers in f(V). The ƛ-number of G, denoted by ƛ(G), is the minimum span over all L(2,1)-labelings of G. We consider the ƛ-number of Pn ☒ Cm and for n ≤ 11 the ƛ-number of Cn ☒ Cm. We determine ƛ-numbers of graphs of interest with the exception of a finite number of graphs and we improve the bounds on the ƛ-number of Cn ☒ Cm, m ≥ 24 and n ≥ 26.
Ključne besede: mathematics, graph theory
Objavljeno v DKUM: 15.06.2017; Ogledov: 1049; Prenosov: 337
.pdf Celotno besedilo (2,31 MB)
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9.
1-factors and characterization of reducible faces of plane elementary bipartite graphs
Andrej Taranenko, Aleksander Vesel, 2012, izvirni znanstveni članek

Opis: As a general case of molecular graphs of benzenoid hydrocarbons, we study plane bipartite graphs with Kekulé structures (1-factors). A bipartite graph ▫$G$▫ is called elementary if ▫$G$▫ is connected and every edge belongs to a 1-factor of ▫$G$▫. Some properties of the minimal and the maximal 1-factor of a plane elementary graph are given. A peripheral face ▫$f$▫ of a plane elementary graph is reducible, if the removal of the internal vertices and edges of the path that is the intersection of ▫$f$▫ and the outer cycle of ▫$G$▫ results in an elementary graph. We characterize the reducible faces of a plane elementary bipartite graph. This result generalizes the characterization of reducible faces of an elementary benzenoid graph.
Ključne besede: mathematics, graph theory, plane elementary bipartite graph, reducible face, benzenoid graph
Objavljeno v DKUM: 31.03.2017; Ogledov: 974; Prenosov: 379
.pdf Celotno besedilo (139,73 KB)
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10.
Synthesis of micro-composite beads with magnetic nano-particles embedded in porous CaCO[sub]3 matrix
Alenka Vesel, Aljoša Košak, David Haložan, Kristina Eleršič, 2012, izvirni znanstveni članek

Opis: A method for synthesis of soft magnetic microbeads is presented. The microbeads are made from magnetic nanoparticles dispersed in CaCO3 (calcium carbonate) matrix. The composite beads are almost perfectly spherical with a diameter of few micrometers. The majority of the composite beads consists of a porous CaCO3 matrix. Magnetic nanoparticles with a size of about 10-15 nm are made of Fe2O3. They are captured inside the pores of CaCO3 matrix during its formation. CaCO3 matrix is formed by crystallization from saturated solution of sodium carbonate and calcium chloride. The composite beads are coated with a layer of functionalized polymer. The magnetic microbeads were characterized by SEM and XPS. Different functional groups were detected by XPS measurements including SO3–,NH3+,NH2,CO32– and OH groups. The results indicate that the iron oxide particles are absent on the surface and that the polymer coating serves as a good biocompatible film.
Ključne besede: composite, surface characterization, XPS, functionalization, Fe nanoparticles, microbeads
Objavljeno v DKUM: 23.03.2017; Ogledov: 1180; Prenosov: 108
.pdf Celotno besedilo (429,86 KB)
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