1. How does day-to-day stress appraisal relate to coping among office workers in academia? : an ecological momentary assessment studyStephanie Hulin, Larissa Bolliger, Junoš Lukan, Anneleen Caluwaerts, Rosalie De Neve, Mitja Luštrek, Dirk De Bacquer, Els Clays, 2023, izvirni znanstveni članek Povzetek: Existing literature indicates that academic staff experience increasing levels of work stress. This study investigated associations between day-to-day threat and challenge appraisal and day-to-day problem-focused coping, emotion-focused coping, and seeking social support among academic office workers. This study is based on an Ecological Momentary Assessment (EMA) design with a 15-working day data collection period utilising our self-developed STRAW smartphone application. A total of 55 office workers from academic institutions in Belgium (n = 29) and Slovenia (n = 26) were included and 3665 item measurements were analysed. Participants were asked approximately every 90 min about their appraisal of stressful events (experienced during the working day) and their coping styles. For data analysis, we used an unstructured covariance matrix in our linear mixed models. Challenge appraisal predicted problem-focused coping and threat appraisal predicted emotion-focused coping. Our findings suggest an association between threat appraisal as well as challenge appraisal and seeking social support. Younger and female workers chose social support more often as a coping style. While working from home, participants were less likely to seek social support. The findings of our EMA study confirm previous research on the relationship between stress appraisal and coping with stress. Participants reported seeking social support less while working from home compared to working at the office, making the work location an aspect that deserves further research.
Ključne besede: academic setting, coping, work stress
Objavljeno v DiRROS: 25.03.2024; Ogledov: 104; Prenosov: 22
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2. Quality checking of polymer modified bitumens in SloveniaMarjan Tušar, Lidija Ržek, Mojca Ravnikar Turk, 2021, objavljeni znanstveni prispevek na konferenci Povzetek: For many years the properties of bitumen have been determined based on mechanical tests as needle penetration, Ring&Ball and Fraass fracture temperature. For elastomer (styrene-butadiene-styrene) polymer modified bitumens these tests are not sufficient to show the important differences in bitumens. Elastic recovery and cohesion provide better insight, but rheological properties cannot be adequately described with conventional test. The requirements of the polymer modified bitumens (PmB) in Europe were defined in EN14023 in 2010 [1]. Since then several new tests were introduced in the research field and their procedures improved. In the European Standards Committee (CEN) TC 336, there is on-going work to develop performance related specifications. New laboratory test methods from American standards were adapted and transformed into EN standards (bitumen laboratory aging methods and rheological tests). These test methods are not yet employed in the cur-rent PmB European standard, however, the draft prEN 14023, April 2020 [2] suggests these new tests. In the recent years at ZAG Laboratory for asphalts and bitumen-based products long-term aging of bitumen by pressure aging vessel (PAV) and rheological tests were introduced. Traditional bitumen test methods are performed together with new rheological testse.g. Dynamic Shear Rheometer (DSR) testing, to characterize complex modulus and phase angle, and Multiple Stress Creep Recovery Test (MSCRT) in order to develop a preliminary data base on PmB’s, which are frequently used in Slovenia. The paper presents the current requirements for PmB’s in Slovenia and test results on PmB 45/80-65, original, laboratory aged and extracted from produced asphalt mixtures.
Ključne besede: polymer modified bitumen, recovered bitumen, laboratory ageing, dynamic shear rheometer, multiple stress creep recovery test
Objavljeno v DiRROS: 28.02.2024; Ogledov: 133; Prenosov: 91
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3. In vitro evaluation of stress corrosion cracking susceptibility of PEO-coated rare-earth magnesium alloy WE43Julia Nachtsheim, Songyun Ma, Jaka Burja, Bernd Markert, 2024, izvirni znanstveni članek Ključne besede: stress corrosion cracking, PEO coating, biodegradable magnesium alloys, SCC test setup, in vitro experiments
Objavljeno v DiRROS: 07.02.2024; Ogledov: 153; Prenosov: 72
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4. Complex interdependency of microstructure, mechanical properties, fatigue resistance, and residual stress of austenitic stainless steels AISI 304LPatricia Jovičević Klug, Matic Klug Jovičević, Michael Rohwerder, Matjaž Godec, Bojan Podgornik, 2023, izvirni znanstveni članek Ključne besede: stainless steel, AISI 304L, deep cryogenic treatment (DCT), microstructure, mechanical properties, fatigue, residual stress
Objavljeno v DiRROS: 02.02.2024; Ogledov: 166; Prenosov: 82
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5. Elucidating nucleation stages of transgranular stress corrosion cracking in austenitic stainless steel by in situ electrochemical and optical methodsSarmiento Klapper Helmuth, Bojan Zajec, Andreas Heyn, Andraž Legat, 2019, izvirni znanstveni članek Povzetek: The pitting and environmentally assisted cracking resistance of austenitic stainless steels (SS) is challenged in several industrial applications particularly those involving hot chloride-concentrated streams. Directional drilling used in the oil and gas exploration is one of these applications. Indeed, high strength CrMn-SS commonly used in drilling technology have a high tendency to fail by stress corrosion cracking (SCC) preceded by localized corrosion once subjected to highly chloride-concentrated drilling fluids at elevated temperatures. A comprehensive understanding regarding the mechanisms governing the transition from pitting into SCCis not currently available, though. Therefore, mechanistic aspects such as the effect of loading conditions on pit nucleation and repassivation as well as the synergistic effect between pit stabilization and the nucleation of a stress corrosion crack are of great practical significance. To investigate this an electrochemical-, optical- and mechanical- monitored SCC test was conducted on a CrMn-SS in an alkaline brine at elevated temperature. The transition from metastable to stable pitting and subsequently to SCC in this system was documented in-situ for the first time. Results supported H.S. Isaacs postulates regarding the interpretation of electrochemical signals and demonstrated that loading conditions affect pit nucleation and repassivation leading to a higher susceptibility of the material to pitting, which preceded SCC.
Ključne besede: pitting corrosion, stress corrosion cracking, monitoring, elektrochemical noise, austenitic stainless steel
Objavljeno v DiRROS: 23.11.2023; Ogledov: 205; Prenosov: 171
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6. Depassivation and repassivation of stainless steels by stepwise pH changeEmir Mujanović, Bojan Zajec, Andraž Legat, Tadeja Kosec, Janez Kovač, Gregor Mori, Stefan Hönig, Gerald Zehethofer, 2020, izvirni znanstveni članek Povzetek: Immersion tests with different stainless steels have been performed, while the pH was stepwise decreased and then increased again. During 8.5-day exposure, the depassivation and repassivation pH values as a function of pitting resistance equivalent number were determined. There is always a gap between both pH values (depassivation and repassivation), indicating that for every steel, there are conditions where an existing passive layer can be maintained but cannot be rebuilt after depassivation. In such environments, the passive layer is thicker, consisting mainly of molybdenum and iron rich oxides, while chromium is dissolved. Usually, depending on conditions, the passive layer is more chromium-rich, especially the inner layer. This is relevant, for example, for acidizing jobs in oil and gas industry, proving that repassivation after acidizing will happen promptly, when the pH is increased again.
Ključne besede: stress corrosion cracking, surface finish impact, tapered tensile specimen, autoclave, accelerated testing, light water nuclear reactor, critical threshold stress
Objavljeno v DiRROS: 30.08.2023; Ogledov: 300; Prenosov: 154
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7. Stress corrosion crack initiation testing with tapered specimens in high-temperature water - results of a collaborative research projectRik-Wouter Bosch, Stefan Ritter, Matthias Herbst, Renate Kilian, Grace Burke, Jonathan Duff, Fabio Scenini, Yuchen Gu, Alice Dinu, Ulla Ehrnsten, Aki Toivonen, Radek Novotny, Oliver Martin, Francisco Javier Perosanz, Andraž Legat, Bojan Zajec, 2020, izvirni znanstveni članek Povzetek: The applicability of an accelerated test technique using tapered tensile specimens for investigating the stress corrosion crack (SCC) initiation behaviour of structural materials in high-temperature water was assessed in the framework of a European collaborative research project (MICRIN – MItigation of CRack INitiation). The main advantage of using a tapered geometry is, that in a single test a stress gradient is obtained through the gauge length, and therefore a stress threshold for SCC initiation can be determined in a reasonable timeframe. This method was used to investigate two different materials that were known to be susceptible to SCC in light water reactor environment: a high-Si stainless steel and a Ni-base weld metal (Alloy 182). The results of the international test programme confirmed that the tapered specimen test methodology could be used to identify a SCC initiation stress threshold, albeit that significant scatter was present in the data.
Ključne besede: stress corrosion cracking, surface finish impact, tapered tensile specimen, autoclave, accelerated testing, light water nuclear reactor, critical threshold stress
Objavljeno v DiRROS: 28.08.2023; Ogledov: 271; Prenosov: 145
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8. Mass concrete with EAF steel slag aggregate : workability, strength, temperature rise, and environmental performanceDavor Kvočka, Jakob Šušteršič, Alenka Mauko Pranjić, Ana Mladenovič, 2022, izvirni znanstveni članek Povzetek: Temperature control is the primary concern during the design and construction process of mass concrete structures. As the concrete production has an enormous negative environmental impact, the development of green mass concretes will eventually become as important as the thermal characteristics. Therefore, this paper investigates the use of Electric Arc Furnace (EAF) steel slag aggregate for the partial replacement of the natural aggregate in the production of mass concrete. The impact of EAF steel aggregate on mass concrete workability, strength, and thermal behaviour was analysed. In addition, a cradle-to-gate LCA study was conducted to evaluate the environmental footprint and sustainability potential of the tested mass concrete mixtures. The study results suggest that the use of EAF steel slag aggregate in combination with a low-heat cement with a high content of blast furnace slag can significantly lower the temperature, reduce the environmental impact, and increase the sustainability potential of mass concrete, while at the same time providing sufficient workability and compressive strength. The study results indicate that EAF steel slag can be upcycled into an aggregate for the production of green mass concrete mixtures.
Ključne besede: mass concrete, thermal stress, EAF steel slag, green concrete, LCA, sustainability, open access
Objavljeno v DiRROS: 31.05.2023; Ogledov: 284; Prenosov: 206
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9. The association between day-to-day stress experiences, recovery, and work engagement among office workers in academia : an Ecological Momentary Assessment studyLarissa Bolliger, Ellen Baele, Elena Colman, Gillian Debra, Junoš Lukan, Mitja Luštrek, Dirk De Bacquer, Els Clays, 2023, izvirni znanstveni članek Povzetek: Objectives. This study aimed to investigate the associations between day-to-day work-related stress exposures (i.e., job demands and lack of job control), job strain, and next-day work engagement among office workers in academic settings. Additionally, we assessed the influence of psychological detachment and relaxation on next-day work engagement and tested for interaction effects of these recovery variables on the relationship between work-related stressors and next-day work engagement. Methods. Office workers from two academic settings in Belgium and Slovenia were recruited. This study is based on an Ecological Momentary Assessment (EMA) with a 15-working day data collection period using our self-developed STRAW smartphone application. Participants were asked repeatedly about their work-related stressors, work engagement, and recovery experiences. Fixed-effect model testing using random intercepts was applied to investigate within- and between-participant levels. Results. Our sample consisted of 55 participants and 2710 item measurements were analysed. A significant positive association was found between job control and next-day work engagement (β = 0.28, p < 0.001). Further, a significant negative association was found between job strain and next-day work engagement (β = −0.32, p = 0.05). Furthermore, relaxation was negatively associated with work engagement (β = −0.08, p = 0.03). Conclusions. This study confirmed previous results, such as higher job control being associated with higher work engagement and higher job strain predicting lower work engagement. An interesting result was the association of higher relaxation after the working day with a lower next-day work engagement. Further research investigating fluctuations in work-related stressors, work engagement, and recovery experiences is required.
Ključne besede: work-related stress, stress exposure, work engagement, office workers, academia
Objavljeno v DiRROS: 04.05.2023; Ogledov: 337; Prenosov: 153
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10. Stable isotope composition in tree rings of Fagus sylvatica L. saplings reflects environmental variation induced by silviculture and microsite factorsJanez Kermavnar, Tom Levanič, Lado Kutnar, 2023, izvirni znanstveni članek Povzetek: Natural regeneration of tree species is sensitive to silvicultural interventions. This study aimed to investigate the effects of different cutting intensities and local topographic and soil conditions on the composition of stable carbon (δ13C) and oxygen (δ18O) isotopes in wood of young beech (Fagus sylvatica L.) trees. Beech saplings in the regeneration layer were sampled in summer 2018 at three study sites in Dinaric fir-beech forests in the karst area of Slovenia. Three different cutting intensities were performed in 2012: i) no cutting (control), ii) 50% cutting of the stand’s growing stock creating thinned stands, and iii) 100% cutting of the stand’s growing stock creating 0.4 ha canopy gaps. We show that δ13C increased along the gradient of cutting intensity. On average, δ13C values in the tree rings were ∼ 2‰ increased in trees from canopy gaps than from closed control stands. Furthermore, δ13C was higher on south-facing slopes characterized by higher air temperatures and lower relative humidity compared to north-facing slopes of karst sinkholes. Additionally, the results suggest a dependence of δ18O on interannual and cross-site climatic variations, particularly in the case of summer precipitation amount. δ18O also responded to soil depth, with beech individuals exhibiting lower values on deeper soils, presumably characterized by higher soil water availability compared to shallow soils. The results are discussed in the context of future climate change, as many beech-dominated forests on karst terrain in the Dinaric Mountains are particularly affected by climate warming and drying due to prolonged and reoccurring summer droughts, intensified large-scale disturbances, and often shallow soils with low water storage capacity.
Ključne besede: stable carbon isotopes, stable oxygen isotopes, tree cutting, microclimate, drought stress, dinaric fir-beech forests
Objavljeno v DiRROS: 05.04.2023; Ogledov: 863; Prenosov: 256
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