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1.
Jordan structures of nilpotent matrices in the centralizer of a nilpotent matrix with two Jordan blocks of the same size
Duško Bogdanić, Alen Ðurić, Sara Koljančić, Polona Oblak, Klemen Šivic, 2024, original scientific article

Abstract: In this paper we characterize all nilpotent orbits under the action by conjugation that intersect the nilpotent centralizer of a nilpotent matrix $B$ consisting of two Jordan blocks of the same size. We list all the possible Jordan canonical forms of the nilpotent matrices that commute with $B$ by characterizing the corresponding partitions.
Keywords: nilpotent matrix, centralizer, nilpotent orbit
Published in DiRROS: 26.03.2024; Views: 34; Downloads: 14
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2.
Gene immunotherapy of colon carcinoma with IL-2 and IL-12 using gene electrotransfer
Tilen Komel, Maša Omerzel, Urška Kamenšek, Katarina Žnidar, Urša Lampreht Tratar, Simona Kranjc Brezar, Klemen Dolinar, Sergej Pirkmajer, Gregor Serša, Maja Čemažar, 2023, original scientific article

Abstract: Gene immunotherapy has become an important approach in the treatment of cancer. One example is the introduction of genes encoding immunostimulatory cytokines, such as interleukin 2 and interleukin 12, which stimulate immune cells in tumours. The aim of our study was to determine the effects of gene electrotransfer of plasmids encoding interleukin 2 and interleukin 12 individually and in combination in the CT26 murine colon carcinoma cell line in mice. In the in vitro experiment, the pulse protocol that resulted in the highest expression of IL-2 and IL-12 mRNA and proteins was used for the in vivo part. In vivo, tumour growth delay and also complete response were observed in the group treated with the plasmid combination. Compared to the control group, the highest levels of various immunostimulatory cytokines and increased immune infiltration were observed in the combination group. Long-term anti-tumour immunity was observed in the combination group after tumour re-challenge. In conclusion, our combination therapy efficiently eradicated CT26 colon carcinoma in mice and also generated strong anti-tumour immune memory.
Keywords: colon carcinoma, gene electrotransfer, gene immunotherapy
Published in DiRROS: 21.03.2024; Views: 72; Downloads: 43
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3.
4.
Comparison of elemental composition of surface and subsurface soils on national level and identification of potential natural and anthropogenic processes influencing its composition
Emil Pučko, Gorazd Žibret, Klemen Teran, 2024, original scientific article

Abstract: The elemental composition of soils is governed by geogenic processes and anthropogenic activities. A comprehensive soil study was conducted on a national level, in which the elemental composition of soils from two different layers was compared with the intention to differentiate between natural and anthropogenic sources of elemental enrichments. Topsoil (0–5 cm) and subsoil (20–30 cm) samples were collected from 249 different locations on a national scale (Slovenia). Elemental composition for 55 major, minor, and trace elements (ICP-MS, aqua regia digestion) was determined on the fraction <0.063 mm. By calculating the enrichment ratios in different lithological units, it was determined that levels of Ti are higher in soils overlying metamorphic and igneous rocks, Zr and Ca are more abundant over carbonates, while levels of Ni are higher in soils overlying marlstones. Elevated levels of Hg were detected in subsoils in the historical Hg mining area in Idrija, which indicates the presence of nearby orebodies as a potential source for the geochemical anomaly. Spatial distribution of elements showed that higher levels of Pb, Zn, Cu, and Hg were detected in topsoils of urban areas, indicating that anthropogenic sources could be the potential cause of soil contamination. Pb, Zn, Cu, and Hg levels were up to four times higher in topsoils compared to subsoils sampled at historical mining areas (e.g., Mežica, Idrija, Litija), which shows that historical mining left a significant environmental impact. Although mining and smelting activities ended a few decades ago, soils in some areas are still heavily enriched with various metals. Some other potential anthropogenic sources of elements were identified, such as farming and ironworks. Based on the results of this study, we can conclude that by comparing elemental compositions of soils from different layers, we can recognise the origin of elemental enrichments.
Keywords: smelting, mining, urbanisation, traffic, ironworks, weathering
Published in DiRROS: 18.03.2024; Views: 54; Downloads: 23
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5.
Mechanisms of premature fracture in modular neck stems made of CoCrMo/Ti6Al4V and Ti6Al4V/Ti6Al4V alloy
Drago Dolinar, Miro Gorenšek, Klemen Avsec, Barbara Šetina, Matej Hočevar, Matjaž Godec, Borut Žužek, Mojca Debeljak, Monika Jenko, John T. Grant, Boštjan Kocjančič, 2023, original scientific article

Abstract: In this paper, we present the mechanisms of premature fracture of modular neck stems in two case studies: (I) when the neck and stem are both made of the same Ti6Al4V alloy, and (II) when the neck and stem are made from two different alloys, CoCrMo and Ti6Al4V alloy. Our study integrates two orthopedic patients who have undergone primary uncemented THA for usual indications in two orthopedic centers (Community Health Centre and University Medical Centre). Both centers are part of the national public health care system. Both surgeries were performed by two skilled orthopedic surgeons with more than 10 years of experience in THA. The survivorship of the modular neck of cast CoCrMo alloy was 24 months. The survivorship of the modular neck from Ti6Al4V alloy was 84 months. Multivariate analyses were performed to assess the differences in the fretting, corrosion, and fatigue of the two prematurely failed modular neck stems: stereo light microscopy (SLM), scanning electron microscopy (SEM), X-ray energy-dispersive spectroscopy (EDS), and electron backscatter diffraction (EBSD). Patient demographic information, including sex, age, body mass index, survivorship of implants, and reason for the revision, was collected from medical records. We found that fretting and fatigue occurred on both neck-stem retrievals due to additional galvanic corrosion, but the CoCrMo/Ti6Al4V alloy system suffered more corrosion due to additional galvanic corrosion and fractured earlier than the Ti6Al4V/Ti6Al4V metal alloy system. Both metallic alloy systems used in this application are known to be highly corrosion-resistant, but the bio-tribo-corrosion processes need to be understood in detail and characterized so that appropriate improvements in design and materials can be made.
Keywords: total hip arthroplasty, modular neck, Ti6Al4V alloy, CoCrMo alloy, corrosion
Published in DiRROS: 07.02.2024; Views: 174; Downloads: 87
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6.
7.
Effect of sucrose concentration on streptococcus mutans adhesion to dental material surfaces
Anamarija Zore, Franc Rojko, Nives Matijaković Mlinarić, Jona Veber, Aleksander Učakar, Roman Štukelj, Andreja Pondelak, Andrijana Sever Škapin, Klemen Bohinc, 2024, original scientific article

Abstract: Enamel demineralization, known as dental caries, is instigated by the bacterium Streptococcus mutans, which generates acid during carbohydrate metabolism. Among carbohydrates, sucrose is the most cariogenic and capable of biofilm formation. This study aimed to explore and comprehend Streptococcus mutans’ adherence to two prevalent dental material surfaces, i.e., a cobalt–chromium(Co-Cr) alloy and a resin-based composite, under the influence of various sucrose concentrations. To understand bacterial adhesion, the surfaces were characterized using profilometry, tensiometry, and surface charge measurements. Bacterial adhesion was evaluated using scanning electron microscopy and crystal violet dye methods. Results revealed that the composite surface exhibited greater rough-ness compared with the Co-Cr alloy surface. Both surfaces displayed hydrophilic properties and a negative surface charge. Bacterial adhesion experiments indicated lower bacterial adherence to the Co-Cr alloy than to the composite surface before the addition of sucrose. However, the introduction of sucrose resulted in biofilm development on both surfaces, showcasing a similar increase in bacterial adhesion, with the highest levels being observed at a 5% sucrose concentration in the bacterial suspension. In conclusion, the findings suggest sucrose-rich foods could facilitate bacterial adaptation despite less favorable surface characteristics, thereby promoting biofilm formation.
Keywords: bacterial adhesion, streptococcus mutans, dental material surfaces, sucrose concentration
Published in DiRROS: 31.01.2024; Views: 127; Downloads: 52
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8.
Manual for use of Al-containing residues in low-carbon mineral binders
Sabina Dolenec, Katja Malovrh Rebec, Anja Lešek, Katarina Šter, Lea Žibret, Gorazd Žibret, Klemen Teran, Emil Pučko, Ildikó Merta, Bojan Poletanovic, Elena Yaneva, Peter Kesserű, Ildikó Kovács, Bence Kószó, Alexandra Németh, Richard Laucournet, Mustafa Hadžalić, Emilija Fidanchevski, Biljana Angjusheva, Vojo Jovanov, Miloš Nenadović, Snežana B. Nenadović, Ivana Vukanac, Liljana Kraljević, Mojca Loncnar, Andrej Ipavec, 2020, dictionary, encyclopaedia, lexicon, manual, atlas, map

Abstract: Današnje družbe si ni več mogoče predstavljati brez sodobne infrastrukture, ki temelji na uporabi različnih materialov ter zahteva veliko porabo energije. Vzporedno s proizvodnjo materialov, nastajajo ogromne količine različnih industrijskih in rudarskih ostankov (odpadki/stranski proizvodi), ki jih trenutno ne izkoriščamo, sama odlagališča pa so premalo raziskana. Cilj Evropske unije (EU) je povečati učinkovito rabo virov in ponudbo sekundarnih surovin z recikliranjem, popisom odpadkov iz rudarskih in drugih industrijskih dejavnosti ter njihova ponovna uporaba. Veliko industrijskih in rudarskih odpadkov je obogatenih z aluminijem (Al), zato lahko nadomeščajo naravne vire Al v mineralnih veznih, vendar njihova uporaba zahteva obsežno poznavanje njihovih kemijskih, mineraloških, radioloških in fizikalnih lastnosti. Priročnik, ki so ga pripravili partnerji projekta RIS-ALiCE obravnava zakonodajne vidike, ki urejajo uporabo sekundarnih surovin v gradbenih proizvodih, opis najpogostejših industrijskih in rudarskih ostankov, ki vsebujejo Al (nahajališča boksitov, rdeče blato, jeklarske žlindre, pepeli iz različnih industrij, itd.), potencial njihove ponovne uporabe in njihov ekonomski vidik, potencialne zahteve/ovire za uporabo sekundarnih surovin v cementni industriji in opis belitno-sulfoaluminatnih cementov, ki so obetavna rešitev za izvajanje krožnega gospodarstva z uporabo velikih količin odloženih industrijskih in rudarskih odpadkov, bogatih z Al.
Keywords: gradbeni proizvodi, ponovna uporaba, ekonomski vidik, industrija cementa, krožno gospodarstvo, industrijski odpadki, zakonodaja, elektronske knjige
Published in DiRROS: 22.01.2024; Views: 158; Downloads: 68
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9.
Temporal and spatial variability of phloem structure in Picea abies and Fagus sylvatica and its link to climate
Jožica Gričar, Jernej Jevšenak, Kyriaki Giagli, Klemen Eler, Dimitrios Tsalagkas, Vladimir Gryc, Hanuš Vavrčík, Katarina Čufar, Peter Prislan, 2024, original scientific article

Abstract: Using a unique 8-year data set (2010–2017) of phloem data, we studied the effect of temperature and precipitation on the phloem anatomy (conduit area, widths of ring, early and late phloem) and xylem-ring width in two coexisting temperate tree species, Picea abies and Fagus sylvatica, from three contrasting European temperate forest sites. Histometric analyses were performed on microcores taken from tree stems in autumn. We found high interannual variability and sensitivity of phloem anatomy and xylem-ring widths to precipitation and temperature; however, the responses were species- and site-specific. The contrasting response of xylem and phloem-ring widths of the same tree species to weather conditions was found at the two Slovenian sites generally well supplied with precipitation, while at the driest Czech site, the influence of weather factors on xylem and phloem ring widths was synchronised. Since widths of mean annual xylem and phloem increments were narrowest at the Czech site, this site is suggested to be most restrictive for the radial growth of both species. By influencing the seasonal patterns of xylem and phloem development, water availability appears to be the most important determinant of tissue- and species-specific responses to local weather conditions.
Keywords: wood anatomy, early phloem, European beech, late phloem, Norway spruce, sieve element area, xylem-ring width
Published in DiRROS: 19.01.2024; Views: 185; Downloads: 84
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10.
O domorodnosti alpskega kozoroga v Sloveniji
Andreja Nève Repe, Elena Bužan, Borut Toškan, Jernej Javornik, Boštjan Pokorny, Andrej Arih, Lars Zver, Maruša Prostor, Miha Krofel, Matija Stergar, Klemen Jerina, Hubert Potočnik, Rok Černe, Aleš Poljanec, 2023, professional article

Abstract: Alpski kozorog (Capra ibex) je alpski endemit. Na območju Slovenije naj bi bila vrsta iztrebljena v drugi polovici 17. stoletja, globalno pa je bila zaradi prelova na robu izumrtja konec 19. stoletja. Preživela je le populacija na širšem območju parka Gran Paradiso na skrajnem zahodu Alp v Italiji. Zaradi naselitev in drugih varstvenih programov sedaj alpski kozorog živi v celotnih Alpah, vključno s Slovenijo. Vendar pri nas njegove populacije nazadujejo in so v zelo slabem stanju, kar je lahko rezultat več dejavnikov. Malo izvornih osebkov ob naselitvah, zgodovinska ozka grla in ločenost kolonij so povzročili parjenje v sorodstvu, kar je slabšalo genetsko stanje populacij in lahko negativno vpliva tudi na demografijo. K številčnemu zmanjševanju vrste so lahko prispevale tudi bolezni. Za dolgoročno ohranitev alpskega kozoroga v Sloveniji so nujni takojšnji aktivni ohranitveni ukrepi, pogoj pa je ustrezna opredelitev izvornosti vrste, saj je (bila) zaradi prejšnjih pomanjkljivih podatkov umeščena med tujerodne. V prispevku na podlagi arheo-zooloških, genetskih in preliminarnih habitatnih analiz utemeljujemo, da je v Sloveniji kozorog domorodna vrsta. V raziskavah smo pokazali, da je vrsta živela na ozemlju zdajšnje Slovenije v poznoantičnem in zgodnje srednjeveškem obdobju. Preliminarno smo določili tudi primernost in povezanost habitata kozoroga v slovenskem alpskem svetu ter nakazali verjetne potrebne ukrepe za ohranitev vrste v Sloveniji.
Keywords: Capra ibex, izvornost vrste, programi varstva, Alpe, habitat, genetika
Published in DiRROS: 09.01.2024; Views: 206; Downloads: 58
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