Iskanje po katalogu digitalne knjižnice

Opis: Uporaba različnih adsorpcijskih sredstev za sušenje komprimiranega zraka je ključnega pomena v številnih industrijskih panogah, saj zagotavlja stabilne pogoje za delovanje opreme in preprečuje korozijo. V magistrskem delu smo proučevali razvoj granulirane aktivirane glinice, namenjene uporabi v sušilnikih komprimiranega zraka. Cilj je bil proizvesti granulat iz aluminijevega hidrata, aktivirane glinice in psevdoboehmita v različnih razmerjih, z namenom doseganja čim višje trdote granul, specifične površine 300 m²/g, določene po BET metodi, in kapacitete vodne adsorpcije (SWA) 15 %. V raziskavi smo uporabili dve različni vrsti glinice in tri tipe hidratov, da bi proučili njihov vpliv na lastnosti granulata. Poleg vpliva surovin smo proučevali še vpliv kalcinacije pri različnih temperaturah. Rezultati so pokazali, da delež aluminijevega hidrata pomembno vpliva na trdoto granul. Nižji deleži hidrata so omogočili izdelavo trdnejših granul zaradi manjše poroznosti, medtem ko je dodatek psevdoboehmita izboljšal trdoto, specifično površino in adsorpcijske lastnosti. Najboljši rezultati so bili doseženi pri formulaciji s 35 % hidrata, kjer so granule dosegle najvišjo trdoto 51 N in SWA 13,3 %, kar se približuje zastavljenim ciljem, ter z 20 % hidrata, kjer je bila dosežena najvišja specifična površina, ki je znašala 283,05 m2/g. Optimizacija je pokazala, da kalcinacija pri temperaturah nad 400 °C ni smiselna, saj ne prinaša bistvenih izboljšav in povečuje energetske stroške. Opravljene so bile tudi XRD analize za boljši vpogled v strukturno sestavo končnih produktov. Ugotovljena sta bila prevlada amorfnih faz pri nižjih temperaturah in prehod v χ ter κ glinico pri višjih temperaturah. Čeprav cilji niso bili povsem doseženi, raziskava predstavlja pomemben vpogled v vpliv surovin in procesnih parametrov na lastnosti granulata. Naše ugotovitve ponujajo trdno osnovo za nadaljnje raziskave in izboljšave materialov za doseganje konkurenčnosti na trgu.
Ključne besede: aktivirana glinica, aluminijev hidrat, adsorbent, granuliranje, adsorpcija
Objavljeno v DKUM: 06.05.2025; Ogledov: 0; Prenosov: 0
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Opis: Background: This study aimed to quantitatively evaluate the learning curve of laparoscopic liver resection (LLR) of a single surgeon. Patients and methods: A retrospective review of a prospectively maintained database of liver resections was conducted. 171 patients undergoing pure LLRs between April 2008 and April 2021 were analysed. The Halls difficulty score (HDS) for theoretical predictions of intraoperative complications (IOC) during LLR was applied. IOC was defined as blood loss over 775 mL, unintentional damage to the surrounding structures, and conversion to an open approach. Theoretical association between HDS and the predicted probability of IOC was utilised to objectify the shape of the learning curve. Results: The obtained learning curve has resulted from thirteen years of surgical effort of a single surgeon. It consists of an absolute and a relative part in the mathematical description of the additive function described by the logarithmic function (absolute complexity) and fifth-degree regression curve (relative complexity). The obtained learning curve determines the functional dependency of the learning outcome versus time and indicates several local extreme values (peaks and valleys) in the learning process until proficiency is achieved. Conclusions: This learning curve indicates an ongoing learning process for LLR. The proposed mathematical model can be applied for any surgical procedure with an existing difficulty score and a known theoretically predicted association between the difficulty score and given outcome (for example, IOC).
Ključne besede: difficulty score, learning curve, laparoscopy, hepatectomy, intraoperative complications, surgical procedures
Objavljeno v DKUM: 07.04.2025; Ogledov: 0; Prenosov: 2
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Opis: Pedestrian safety is a well-known issue, such that many road safety associations emphasize measures to improve this aspect. One of the main conflict points is pedestrian crossings, where motorized and non-motorized traffic flows directly interact and where pedestrian attention and reaction are two elements that can strongly influence their safety. Nowadays, these aspects are often deviated by the use of smartphones to surf the Internet or social media. The aim of the present study is to find out (1) whether and how intersection typology affects pedestrian behavior, both in terms of attention and crossing performance, and (2) whether and how gaze and behavioral characteristics are affected by smartphone use and social media browsing. To achieve this goal, eye-tracking technology was used to obtain qualitative and quantitative information on the number of fixations, their duration, and reaction times of pedestrians. Additionally, from the eye-tracking videos, it was possible to derive pedestrian waiting times, crossing times, and speeds. Statistical tests were conducted to determine if there is a significant difference in pedestrian behavior at the three different types of intersections and in their behavior when using or not using their device. Results confirm the initial hypotheses and quantify the difference in pedestrian gaze behavior and crossing performance when walking across three different types of signalized crosswalks.
Ključne besede: pedestrian, eye-tracking, gaze behavior, reaction time, signalized intersection, crossing behavior
Objavljeno v DKUM: 13.03.2025; Ogledov: 0; Prenosov: 5
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Opis: An L(d,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 d and the labels on vertices at distance two differ by at least one, where d≥1. The span of f is the difference between the largest and the smallest numbers in f(V). The λ1d-number of G, denoted by λ1d(G), is the minimum span over all L(d,1)-labelings of G. We prove that λ1d(X)≤2d+2, with equality if 1≤d≤4, for direct graph bundle X=Cm×σℓCn and Cartesian graph bundle X=Cm□σℓCn, if certain conditions are imposed on the lengths of the cycles and on the cyclic ℓ-shift σℓ.
Ključne besede: L(d, 1)-labeling, λ d 1 -number, direct product of graph, direct graph bundle, Cartesian product of graph, Cartesian graph bundle, cyclic ℓ-shift, channel assignment
Objavljeno v DKUM: 13.03.2025; Ogledov: 0; Prenosov: 6
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Opis: Introduction: Although the distinction between the Community-Associated-Methicillin-Resistant Staphylococcus aureus (CA-MRSA) and Hospital-Associated-Methicillin-Resistant S. aureus (HA-MRSA) has blurred in recent years, the CA-MRSA is an important group because of its potential to cause fulminant and severe infections. Its importance has further increased with the emergence of Livestock-Associated-Methicillin-Resistant S. aureus (LA-MRSA). Methods: In the present study we analysed clonal distributions and virulence factors in presumptive CA-MRSA isolated from January 2014 to December 2015 and compared the results with our previous study from 2010. Phenotypic definition for presumptive CA-MRSA was based on resistance to cefoxitin and oxacillin and susceptibility to at least two of the following four antibiotics: ciprofloxacin, erythromycin, clindamycin and gentamicin. Results:In 2014 and 2015 altogether 304 MRSA isolates fulfilled our screening phenotypic definition, 45 isolates were cultivated from clinical specimens and 259 from screening specimens. Sequence types ST398, LA-MRSA and mecC MRSA increased significantly in 2015 compared to 2010 (p-value <0.05) and were spread over Slovenia. Conclusion:The clonal distribution of presumptive CA-MRSA has changed within the study period in Slovenia. In 2015 the most frequent clone among clinical and screening specimens was a pig-associated clone, ST398, but the number of confirmed ST398 infections remains low. While previously ST398 and mecC positive MRSA strains were geographically limited, they have spread throughout the country since 2010.
Ključne besede: Slovenia, CA-MRSA, LA-MRSA, mecC, spa types, clones
Objavljeno v DKUM: 20.01.2025; Ogledov: 0; Prenosov: 403
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