| 451. |
- Trevisan, Silvia, et al.
(författare)
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Coatings utilization to modify the effective properties of high temperature packed bed thermal energy storage
- 2021
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Ingår i: Applied Thermal Engineering. - : Elsevier. - 1359-4311 .- 1873-5606. ; 185
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Tidskriftsartikel (refereegranskat)abstract
- High-temperature thermal energy storage is becoming more and more important as a key component in concentrating solar power systems and as an economically viable large-scale energy storage solution. Ceramics and natural rocks based packed beds are one of the attracting solutions. For application temperatures above 600 ◦C, radiation heat transfer becomes the dominant heat transfer phenomenon and it greatly influences the performance of thermal storage systems. Coatings with different thermal properties (mainly thermal emissivity and thermal conductivity) could be exploited to modify the effective thermal properties of packed beds. In this work, we present a methodology to account for the thermal effect of a coating layer applied over the pebbles of a packed bed. The influences on the packed bed effective thermal conductivity of several characteristics of the coating material, packed bed arrangement, and filler material are investigated. The results show that low emissivity coatings could reduce the effective thermal conductivity of a rock based packed bed of about 58%, with respect to a similar uncoated solution, already at 800 ◦C. A low emissivity coating could also limit the increase in the thermal effective conductivity from the cold to the hot zone of the storage. Coatings would have a higher influence when applied in packed beds with large size particles, relatively high thermal conductivity of the substrate and void fraction. The application of different coatings, with various thermo-physical properties, in different parts of the storage could modify the effective thermal conductivity distribution and enable a partial control of the thermocline degradation, increasing the storage thermal efficiency.
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| 452. |
- Trevisan, Silvia, et al.
(författare)
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Experimental evaluation of a high-temperature radial-flow packed bed thermal energy storage under dynamic mass flow rate
- 2022
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Ingår i: Journal of Energy Storage. - : Elsevier BV. - 2352-152X .- 2352-1538. ; 54, s. 105236-
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Tidskriftsartikel (refereegranskat)abstract
- High-temperature thermal energy storage is recognized to be a key technology to ensure future sustainable energy generation. Packed bed thermal energy storage is a cost-competitive large-scale energy storage solution. The present work introduces the experimental investigation of an innovative 49.7 kWh(th) radial-flow type high-temperature packed bed thermal energy storage under dynamic mass flow rates. Various dynamic air flow rate profiles, representative of different potential applications, have been tested during the charging process to investigate their influence on the thermodynamic performance of the storage. The outlet thermal power during the discharge has been controlled by managing the air flow rate. Short operational cycles have also been performed. The results show that dynamic mass flow rates can lead to a thermal efficiency reduction between 0.5 % and 5 % with respect to static conditions. Controlling the air mass flow rate could be an efficient strategy to stabilize the thermal power output during the discharge while minimizing peaks in the pressure drop. This work testifies that specific dynamic boundary conditions should be included during the thermal storage design process since they could largely affect the unit thermodynamic performance and potential scale-up. If no specific dynamic profiles are available during the packed bed storage design stage, it is suggested to consider typical dynamic profiles of the air mass flow rate to guarantee limited efficiency reduction during operation.
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| 453. |
- Trevisan, Silvia, et al.
(författare)
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Laboratory prototype of an innovative radial flow packed bed thermal energy storage
- 2022
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Ingår i: SOLARPACES 2020. - : AIP Publishing.
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Konferensbidrag (refereegranskat)abstract
- This work presents a laboratory scale 50kWhth prototype of an innovative radial flow packed bed thermal energy storage. The proposed storage has an inward radial heat transfer fluid flow during charge and a reverted fluid flow, by means of a valve arrangement, during discharge. The storage unit is equipped with differential pressure gauges, mass flow controller and 50?K-thermocouples to accurately measure the thermodynamic behavior of the unit. In order to assess the performance of the proposed thermal energy storage design two specific indicators have been introduced and defined, namely: the temperature uniformity, and the hydrodynamic uniformity. The results of preliminary CFD studies show a maximum temperature deviation of 20°C along the storage axial direction and uniformity indexes higher than 90%.
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| 454. |
- Tsereteli, Neli, et al.
(författare)
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Impact of insufficient sleep on dysregulated blood glucose control under standardised meal conditions
- 2022
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 0012-186X .- 1432-0428. ; 65:2, s. 356-365
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Tidskriftsartikel (refereegranskat)abstract
- Aims/hypothesis: Sleep, diet and exercise are fundamental to metabolic homeostasis. In this secondary analysis of a repeated measures, nutritional intervention study, we tested whether an individual’s sleep quality, duration and timing impact glycaemic response to a breakfast meal the following morning. Methods: Healthy adults’ data (N = 953 [41% twins]) were analysed from the PREDICT dietary intervention trial. Participants consumed isoenergetic standardised meals over 2 weeks in the clinic and at home. Actigraphy was used to assess sleep variables (duration, efficiency, timing) and continuous glucose monitors were used to measure glycaemic variation (>8000 meals). Results: Sleep variables were significantly associated with postprandial glycaemic control (2 h incremental AUC), at both between- and within-person levels. Sleep period time interacted with meal type, with a smaller effect of poor sleep on postprandial blood glucose levels when high-carbohydrate (low fat/protein) (pinteraction = 0.02) and high-fat (pinteraction = 0.03) breakfasts were consumed compared with a reference 75 g OGTT. Within-person sleep period time had a similar interaction (high carbohydrate: pinteraction = 0.001, high fat: pinteraction = 0.02). Within- and between-person sleep efficiency were significantly associated with lower postprandial blood glucose levels irrespective of meal type (both p < 0.03). Later sleep midpoint (time deviation from midnight) was found to be significantly associated with higher postprandial glucose, in both between-person and within-person comparisons (p = 0.035 and p = 0.051, respectively). Conclusions/interpretation: Poor sleep efficiency and later bedtime routines are associated with more pronounced postprandial glycaemic responses to breakfast the following morning. A person’s deviation from their usual sleep pattern was also associated with poorer postprandial glycaemic control. These findings underscore sleep as a modifiable, non-pharmacological therapeutic target for the optimal regulation of human metabolic health. Trial registrationClinicalTrials.gov NCT03479866. Graphical abstract: [Figure not available: see fulltext.]
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| 455. |
- Tserga, Evangelia, et al.
(författare)
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Circadian vulnerability of cisplatin-induced ototoxicity in the cochlea
- 2020
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Ingår i: The FASEB Journal. - : John Wiley & Sons. - 0892-6638 .- 1530-6860. ; 34:10, s. 13978-13992
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Tidskriftsartikel (refereegranskat)abstract
- The chemotherapeutic agent cisplatin is renowned for its ototoxic effects. While hair cells in the cochlea are established targets of cisplatin, less is known regarding the afferent synapse, which is an essential component in the faithful temporal transmission of sound. The glutamate aspartate transporter (GLAST) shields the auditory synapse from excessive glutamate release, and its loss of function increases the vulnerability to noise, salicylate, and aminoglycosides. Until now, the involvement of GLAST in cisplatin-mediated ototoxicity remains unknown. Here, we test in mice lacking GLAST the effects of a low-dose cisplatin known not to cause any detectable change in hearing thresholds. When administered at nighttime, a mild hearing loss in GLAST KO mice was found but not at daytime, revealing a potential circadian regulation of the vulnerability to cisplatin-mediated ototoxicity. We show that the auditory synapse of GLAST KO mice is more vulnerable to cisplatin administration during the active phase (nighttime) when compared to WT mice and treatment during the inactive phase (daytime). This effect was not related to the abundance of platinum compounds in the cochlea, rather cisplatin had a dose-dependent impact on cochlear clock rhythms only after treatment at nighttime suggesting that cisplatin can modulate the molecular clock. Our findings suggest that the current protocols of cisplatin administration in humans during daytime may cause a yet undetectable damage to the auditory synapse, more so in already damaged ears, and severely impact auditory sensitivity in cancer survivors.
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| 456. |
- Tuovinen, Heimo, et al.
(författare)
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Sensitivity calculations of tunnel fires using CFD
- 1996
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Ingår i: Fire Technology. - 0015-2684. ; 32:2, s. 99-119
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Tidskriftsartikel (refereegranskat)abstract
- Detailed numerical simulations of fires in road tunnels were carried out using the CFD code JASMINE. Fire tests performed in the Ofenegg tunnel have also been validated. A parametric study of fires in an arbitrary 300-m-long tunnel was made, in which the influence of fire size, tunnel width, ventilation and ground slope was investigated. The movement of hazardous temperature and smoke regions as a function of time was calculated to investigate escape possibilities from the tunnel in case of fire.
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| 457. |
- Vamstad, Johan, 1977-
(författare)
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Co-Production and Service Quality : The Case of Cooperative Childcare in Sweden
- 2012
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Ingår i: VOLUNTAS - International Journal of Voluntary and Nonprofit Organizations. - New York : Springer. - 0957-8765 .- 1573-7888. ; 23:4
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Tidskriftsartikel (refereegranskat)abstract
- This article compares results from a study of service quality in cooperative and municipal preschools. The parent cooperative and municipal childcare represents two different schools of thought with regard to service quality. The municipal services have a strong tradition of professionalism in which user participation is not allowed to interfere with the qualified work performed by trained professionals. The parent cooperatives have another tradition in which service quality is developed in a dialogue between users and staff while they co-produce the services together. The former tradition is the dominant one in the Swedish welfare state while the latter is an exception. The conclusion of the article is that service quality is better in the parent cooperative childcare in spite of the widespread assumption in Sweden that service quality is close to synonymous with professionalism.
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| 458. |
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| 459. |
- van Dijk, Laura J. A., 1990-
(författare)
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Interactions between plants, microbes and insects
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Plants interact with an astonishing diversity of insects and microorganisms. Both above- and belowground, plants are attacked by herbivores and pathogens, and interact with mutualists such as pollinating insects and beneficial microorganisms. Insects and microorganisms interacting with plants may also affect one another when sharing the same host, leading to direct and indirect interactions between plants, microorganisms and insects. These interactions may have important ecological and evolutionary consequences for all involved species, and interaction outcomes might be dependent on the timing of the interaction as well as the abiotic and biotic context. Thus, in order to predict the outcome of plant–microbe–insect interactions, we need insights into how interactions vary over time and space and how these are influenced by biotic context, from the perspective of all involved species.In this thesis, my overarching aim was to investigate when and where species interact, and to examine the influence of relative timing and biotic context on the outcomes of plant–microbe–insect interactions from a multi-species perspective. I focussed on two study systems, the pedunculate oak Quercus robur and the wood anemone Anemone nemorosa, and the insects and microorganisms associated with these plants. First, I looked into the drivers behind the spatiotemporal distribution of several fungal pathogens on plants. Specifically, I investigated whether life history traits of pathogens were linked to their metapopulation dynamics. Second, I examined the relative importance of direct and insect-mediated effects of these pathogens on plant performance. Third, I conducted multifactorial growth chamber experiments to investigate performance impacts of interactions from the perspectives of all involved species (plant, insect and pathogen). Lastly, I investigated the influence of time of attacker arrival, early arriving attackers and soil microbial communities on interaction outcomes.I found that life history traits of pathogens were related to some aspects of metapopulation dynamics. These pathogens had direct, negative impacts on plant growth and fitness, while I did not find evidence for insect-mediated effects. For the multifactorial experiments, I observed some impacts of multiple attackers (pathogens and insects) on plant growth, though plants were mostly tolerant to attack. Attackers that shared a host could affect each other’s performances, with effects mostly being asymmetric, though the interaction outcomes were dependent on the time of arrival, early arriving attackers and soil microbial communities.In conclusion, my findings show that i) life history traits may influence where pathogen species occur in space and time, that ii) direct effects of pathogens on plant fitness can dominate insect-mediated effects, and that iii) the outcome of species interactions is often asymmetric and dependent on relative timing as well as biotic context. By identifying some of the drivers behind, and consequences of, plant–microbe–insect interactions, this thesis contributes to the development of a predictive framework for species interactions.
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| 460. |
- van Dijk, Laura J. A., 1990-, et al.
(författare)
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Single, but not dual, attack by a biotrophic pathogen and a sap-sucking insect affects the oak leaf metabolome
- 2022
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Ingår i: Frontiers in Plant Science. - : Frontiers Media S.A.. - 1664-462X. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Plants interact with a multitude of microorganisms and insects, both below- and above ground, which might influence plant metabolism. Despite this, we lack knowledge of the impact of natural soil communities and multiple aboveground attackers on the metabolic responses of plants, and whether plant metabolic responses to single attack can predict responses to dual attack. We used untargeted metabolic fingerprinting (gas chromatography-mass spectrometry, GC-MS) on leaves of the pedunculate oak, Quercus robur, to assess the metabolic response to different soil microbiomes and aboveground single and dual attack by oak powdery mildew (Erysiphe alphitoides) and the common oak aphid (Tuberculatus annulatus). Distinct soil microbiomes were not associated with differences in the metabolic profile of oak seedling leaves. Single attacks by aphids or mildew had pronounced but different effects on the oak leaf metabolome, but we detected no difference between the metabolomes of healthy seedlings and seedlings attacked by both aphids and powdery mildew. Our findings show that aboveground attackers can have species-specific and non-additive effects on the leaf metabolome of oak. The lack of a metabolic signature detected by GC-MS upon dual attack might suggest the existence of a potential negative feedback, and highlights the importance of considering the impacts of multiple attackers to gain mechanistic insights into the ecology and evolution of species interactions and the structure of plant-associated communities, as well as for the development of sustainable strategies to control agricultural pests and diseases and plant breeding.
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