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1.
General Position Sets in Two Families of Cartesian Product Graphs
Danilo Korže, Aleksander Vesel, 2023, izvirni znanstveni članek

Opis: For a given graph G, the general position problem asks for the largest set of vertices S⊆V(G) , such that no three distinct vertices of S belong to a common shortest path of G. The general position problem for Cartesian products of two cycles as well as for hypercubes is considered. The problem is completely solved for the first family of graphs, while for the hypercubes, some partial results based on reduction to SAT are given.
Ključne besede: general position set, cartesian product, hypercube, SAT
Objavljeno v DKUM: 02.04.2024; Ogledov: 59; Prenosov: 5
.pdf Celotno besedilo (405,17 KB)
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2.
Loss of oxygen atoms on well-oxidized cobalt by heterogeneous surface recombination
Domen Paul, Miran Mozetič, Rok Zaplotnik, Jernej Ekar, Alenka Vesel, Gregor Primc, Denis Đonlagić, 2023, izvirni znanstveni članek

Opis: Calorimetry is a commonly used method in plasma characterization, but the accuracy of the method is tied to the accuracy of the recombination coefficient, which in turn depends on a number of surface effects. Surface effects also govern the kinetics in advanced methods such as atomic layer oxidation of inorganic materials and functionalization of organic materials. The flux of the reactive oxygen atoms for the controlled oxidation of such materials depends on the recombination coefficient of materials placed into the reaction chamber, which in turn depends on the surface morphology, temperature, and pressure in the processing chamber. The recombination coefficient of a well-oxidized cobalt surface was studied systematically in a range of temperatures from 300 to 800 K and pressures from 40 to 200 Pa. The coefficient increased monotonously with decreasing pressure and increasing temperature. The lowest value was about 0.05, and the highest was about 0.30. These values were measured for cobalt foils previously oxidized with oxygen plasma at the temperature of 1300 K. The oxidation caused a rich morphology with an average roughness as deduced from atomic force images of 0.9 µm. The results were compared with literature data, and the discrepancy between results reported by different authors was explained by taking into account the peculiarities of their experimental conditions.
Ključne besede: heterogeneous surface recombination, recombination coefficient, cobalt, cobalt oxide, temperature dependence, pressure dependence, plasma, oxygen
Objavljeno v DKUM: 26.03.2024; Ogledov: 78; Prenosov: 6
.pdf Celotno besedilo (3,59 MB)
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3.
Recombination of oxygen atoms on the surface of oxidized polycrystalline nickel : temperature and pressure dependences
Domen Paul, Miran Mozetič, Rok Zaplotnik, Jernej Ekar, Alenka Vesel, Gregor Primc, Denis Đonlagić, 2023, izvirni znanstveni članek

Opis: The recombination of neutral oxygen atoms in the ground state on the oxidized nickel samples was studied experimentally in the range of pressures where the maximum density occurs in weakly ionized low-pressure oxygen plasma, i.e. between 40 and 200 Pa. The recombination coefficient was determined in the flowing afterglow. The source of oxygen atoms was plasma sustained in a quartz tube of inner diameter 4.7 mm by a microwave discharge in the surfatron mode. The recombination coefficient was determined in the afterglow chamber, which was a Pyrex tube with an inner diameter of 36 mm. The density of oxygen atoms in the afterglow chamber was varied by adjusting the discharge power, the gas flow, the pressure, and the position of a recombinator. Such flexibility of the experimental system enabled adjustment of the temperature of the oxidized nickel samples independently from the O-atom density in its vicinity or other parameters. The density of oxygen atoms in the afterglow chamber at various system parameters was determined by the Šorli method, which is reliable, and has an accuracy of about 20%. The recombination coefficient was determined by calorimetry. The coefficient was inversely proportional to the square root of the pressure and exponentially to the sample temperature. Systematic measurements performed at various pressures and temperatures enabled empirical formula, which were explained qualitatively by recombination kinetics.
Ključne besede: heterogenous surface recombination, recombination coefficient, nickel, nickel oxide, temperature
Objavljeno v DKUM: 25.03.2024; Ogledov: 78; Prenosov: 2
.pdf Celotno besedilo (2,44 MB)
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4.
A review of recombination coefficients of neutral oxygen atoms for various materials
Domen Paul, Miran Mozetič, Rok Zaplotnik, Gregor Primc, Denis Đonlagić, Alenka Vesel, 2023, pregledni znanstveni članek

Opis: Relevant data on heterogeneous surface recombination of neutral oxygen atoms available in the scientific literature are reviewed and discussed for various materials. The coefficients are determined by placing the samples either in non-equilibrium oxygen plasma or its afterglow. The experimental methods used to determine the coefficients are examined and categorized into calorimetry, actinometry, NO titration, laser-induced fluorescence, and various other methods and their combinations. Some numerical models for recombination coefficient determination are also examined. Correlations are drawn between the experimental parameters and the reported coefficients. Different materials are examined and categorized according to reported recombination coefficients into catalytic, semi-catalytic, and inert materials. Measurements from the literature of the recombination coefficients for some materials are compiled and compared, along with the possible system pressure and material surface temperature dependence of the materials’ recombination coefficient. A large scattering of results reported by different authors is discussed, and possible explanations are provided.
Ključne besede: heterogeneous surface recombination, recombination coefficient, surface catalicity, catalytic efficiency, atom loss coefficient, oxygen, neutral atoms, plasma
Objavljeno v DKUM: 21.03.2024; Ogledov: 120; Prenosov: 8
.pdf Celotno besedilo (10,51 MB)
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5.
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: 279; Prenosov: 13
.pdf Celotno besedilo (5,34 MB)

6.
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: 416; Prenosov: 24
.pdf Celotno besedilo (2,70 MB)
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7.
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: 1087; Prenosov: 55
.pdf Celotno besedilo (624,54 KB)
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8.
(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: 1303; Prenosov: 111
.pdf Celotno besedilo (4,27 MB)

9.
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: 1211; Prenosov: 170
.pdf Celotno besedilo (803,81 KB)
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10.
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: 1172; Prenosov: 429
.pdf Celotno besedilo (2,39 MB)
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