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1.
The role of ascorbate–glutathione system and volatiles emitted by insect-damaged lettuce roots as navigation signals for insect and slug parasitic nematodes
Žiga Laznik, Mitja Križman, Jure Zekič, Mihaela Roškarič, Stanislav Trdan, Andreja Urbanek Krajnc, 2023, izvirni znanstveni članek

Opis: The effect of wireworm-damaged lettuce roots on the antioxidative defense system (ascorbate–glutathione cycle, photosynthetic pigments) and movement of insect/slug parasitic nematodes towards determined root exudates was studied in a glasshouse experiment. Lettuce seedlings were grown in a substrate soil in the absence/presence of wireworms (Elateridae). The ascorbate– glutathione system and photosynthetic pigments were analyzed by HPLC, while volatile organic compounds (VOC) emitted by lettuce roots were investigated by GC-MS. Herbivore-induced root compounds, namely 2,4-nonadienal, glutathione, and ascorbic acid, were selected for a chemotaxis assay with nematodes Steinernema feltiae, S. carpocapsae, Heterorhabditis bacteriophora, Phasmarhabditis papillosa, and Oscheius myriophilus. Root pests had a negative effect on the content of photosynthetic pigments in the leaves of infested plants, indicating that they reacted to the presence of reactive oxygen species (ROS). Using lettuce as a model plant, we recognized the ascorbate–glutathione system as a redox hub in defense response against wireworms and analyzed its role in root-exudate-mediated chemotaxis of nematodes. Infected plants also demonstrated increased levels of volatile 2,4-nonadienal. Entomopathogenic nematodes (EPNs, S. feltiae, S. carpocapsae, and H. bacteriophora) proved to be more mobile than parasitic nematodes O. myriophilus and P. papillosa towards chemotaxis compounds. Among them, 2,4-nonadienal repelled all tested nematodes. Most exudates that are involved in belowground tritrophic interactions remain unknown, but an increasing effort is being made in this field of research. Understanding more of these complex interactions would not only allow a better understanding of the rhizosphere but could also offer ecologically sound alternatives in the pest management of agricultural systems.
Ključne besede: lettuce, wireworms, ascorbate–glutathione system, root volatile organic compounds, entomopathogenic nematodes, slug parasitic nematodes
Objavljeno v DKUM: 15.02.2024; Ogledov: 163; Prenosov: 7
.pdf Celotno besedilo (3,96 MB)
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2.
Szeged and Mostar root-indices of graphs
Simon Brezovnik, Matthias Dehmer, Niko Tratnik, Petra Žigert Pleteršek, 2023, izvirni znanstveni članek

Opis: Various distance-based root-indices of graphs are introduced and studied in the present article. They are obtained as unique positive roots of modified graph polynomials. In particular, we consider the Szeged polynomial, the weighted-product Szeged polynomial, the weighted-plus Szeged polynomial, and the Mostar polynomial. We derive closed formulas of these polynomials for some basic families of graphs. Consequently, we provide closed formulas for some root-indices and examine the convergence of sequences of certain root-indices. Moreover, some general properties of studied root-indices are stated. Finally, numerical results related to discrimination power, correlations, structure sensitivity, and abruptness of root-indices are calculated, interpreted, and compared to already known similar descriptors.
Ključne besede: Szeged index, Szeged polynomial, Mostar polynomial, root-index, discrimination power, sensitivity
Objavljeno v DKUM: 18.08.2023; Ogledov: 323; Prenosov: 33
.pdf Celotno besedilo (535,31 KB)
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3.
Case report: Endodontic treatment of a permanent maxillary first molar with three roots and six root canals
Marko Novak, Iztok Štamfelj, 2022, kratki znanstveni prispevek

Ključne besede: dental anatomy, dental operating microscope, root canal morphology, rotary endodontic instruments
Objavljeno v DKUM: 16.02.2023; Ogledov: 427; Prenosov: 27
.pdf Celotno besedilo (193,76 KB)
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4.
Methods for detecting fatigue cracks in gears
Aleš Belšak, Jože Flašker, 2009, objavljeni znanstveni prispevek na konferenci

Opis: A crack in the tooth root is the least desirable damage caused to gear units and it often causes failure of gear unit operation. For fault analyses presented in this article, gear units with real damages or faults produced on the basis of numerical simulations of real operating conditions are used; tests were carried out in a laboratory test plant. Damages in gear units can be identified by monitoring vibrations. The influences of a crack in a single-stage gear unit on produced vibrations are presented. Significant changes in tooth stiffness are caused by a fatigue crack in the tooth root whereas, in relation to other faults, changes of other dynamic parameters are more expressed. Non-stationary signals are analysed, using the family of Time Frequency Analysis tools, which include Wavelets and Joint Time Frequency Analyses.
Ključne besede: gear unit, vibrations, tooth root, time frequency analysis tool
Objavljeno v DKUM: 30.06.2017; Ogledov: 1134; Prenosov: 389
.pdf Celotno besedilo (705,13 KB)
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Roots of cube polynomials of median graphs
Boštjan Brešar, Sandi Klavžar, Riste Škrekovski, 2006, izvirni znanstveni članek

Opis: Polinom kock ▫$c(G,x)$▫ grafa ▫$G$▫ je definiran z ▫$sum_{i ge 0}alpha_i(G)x^i$▫, kjer ▫$alpha_i(G)$▫ označuje število induciranih ▫$i$▫-kock v ▫$G$▫. Naj bo ▫$G$▫ medianski graf. Dokazano je, da je vsaka racionalna ničla polinoma ▫$c(G,x)$▫ oblike ▫$-frac{t+1}{t}$▫ za neko celo število ▫$t>0$▫ in da ima ▫$c(G,x)$▫ vedno realno ničlo na intervalu ▫$[-2,-1)$▫. Nadalje ima ▫$c(G,x)$▫ ▫$p$▫-kratno ničlo natanko tedaj, ko je ▫$G$▫ kartezični produkt ▫$p$▫ dreves istega reda. Grafi acikličnih kubičnih kompleksov so karakterizirani kot grafi za katere velja ▫$c(H,-2)=0$▫ za vsak 2-povezan konveksen podgraf ▫$H$▫.
Ključne besede: matematika, teorija grafov, polinom kock, koren, medianski graf, kartezični produkt grafov, mathematics, graph theory, cube polynomial, root, median graph, Cartesian product
Objavljeno v DKUM: 10.07.2015; Ogledov: 1299; Prenosov: 88
URL Povezava na celotno besedilo

8.
Deflection of polymer gear tooth under static load using numerical analysis
Boštjan Zafošnik, Nina Hanžič, Jože Flašker, 2013, objavljeni znanstveni prispevek na konferenci

Ključne besede: polymer gears, stree strain, Young's modulus, gear tooth root
Objavljeno v DKUM: 10.07.2015; Ogledov: 1235; Prenosov: 51
URL Povezava na celotno besedilo

9.
Roots of cube polynomials of median graphs
Boštjan Brešar, Sandi Klavžar, Riste Škrekovski, 2003

Opis: Polinom kock ▫$c(G,X)$▫ grafa ▫$G$▫ je definiran z ▫$sum_{i ge 0}alpha_i(G)x^i$▫, kjer ▫$alpha_i(G)$▫ označuje število induciranih ▫$i$▫-kock v ▫$G$▫. Naj bo ▫$G$▫ medianski graf. Dokazano je, da je vsaka racionalna ničla polinoma ▫$c(G,x)$▫ oblike ▫$-frac{t+1}{t}$▫ za neko celo število ▫$t>0$▫ in da ima ▫$c(G,x)$▫ vedno realno ničlo na intervalu ▫$[-2,-1)$▫. Nadalje ima ▫$c(G,x)$▫ ▫$p$▫-kratno ničlo natanko tedaj, ko je ▫$G$▫ kartezični produkt ▫$p$▫ dreves istega reda. Grafi acikličnih kubičnih kompleksov so karakterizirani kot grafi za katere velja ▫$c(H,-2)=0$▫ za vsak 2-povezan konveksen podgraf ▫$H$▫.
Ključne besede: matematika, teorija grafov, polinom kock, koren, medianski graf, kartezični produkt grafov, mathematics, graph theory, cube polynomial, root, median graph, Cartesian product
Objavljeno v DKUM: 10.07.2015; Ogledov: 1181; Prenosov: 93
URL Povezava na celotno besedilo

10.
Investigation of crack propagation scatter in a gear tooth's root
Stanislav Pehan, Janez Kramberger, Jože Flašker, Boštjan Zafošnik, 2008, izvirni znanstveni članek

Opis: This paper describes the problem of determining crack initiation location and its influence on crack propagation in a gear tooth's root. Three different load positions on the gear tooth's flank were considered for this investigation of crack initiation and propagation. A special test device was used for the single tooth test. It can be concluded from the measurements thata crack can be initiated at very different locations in a tooth's root and then propagate along its own paths. A numerical investigation into a crack initiation's position and its influences on its propagation were carried out within the framework of linear fracture mechanics. The influence of a tooth's load position, the geometry of the tooth's root, and the influence of nonparallel load distribution on the tooth's flank were considered when investigating the crack initiation's position. Results show that linear fracture mechanics can be used for determining crack propagation, if better initial conditions for crack initiation are considered.
Ključne besede: fracture mechanics, crack initiation, experimental crack propagation, numerical crack propagation, crack location, gearbox, tooth root, load distribution, linear elastic fracture mechanics
Objavljeno v DKUM: 01.06.2012; Ogledov: 1683; Prenosov: 102
URL Povezava na celotno besedilo

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