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| 2. |
- Bokhorst, Stef, et al.
(författare)
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Changing Arctic snow cover : A review of recent developments and assessment of future needs for observations, modelling, and impacts
- 2016
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 45:5, s. 516-537
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Forskningsöversikt (refereegranskat)abstract
- Snow is a critically important and rapidly changing feature of the Arctic. However, snow-cover and snowpack conditions change through time pose challenges for measuring and prediction of snow. Plausible scenarios of how Arctic snow cover will respond to changing Arctic climate are important for impact assessments and adaptation strategies. Although much progress has been made in understanding and predicting snow-cover changes and their multiple consequences, many uncertainties remain. In this paper, we review advances in snow monitoring and modelling, and the impact of snow changes on ecosystems and society in Arctic regions. Interdisciplinary activities are required to resolve the current limitations on measuring and modelling snow characteristics through the cold season and at different spatial scales to assure human well-being, economic stability, and improve the ability to predict manage and adapt to natural hazards in the Arctic region.
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| 3. |
- Hamatani, Sayo, et al.
(författare)
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Guided Internet-Based Cognitive Behavioral Therapy for Women With Bulimia Nervosa: Protocol for a Multicenter Randomized Controlled Trial
- 2023
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Ingår i: JMIR Research Protocols. - : JMIR PUBLICATIONS, INC. - 1929-0748. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Background: Individual face-to-face cognitive behavioral therapy is known to be effective for bulimia nervosa (BN). Since foods vary considerably between regions and cultures in which patients live, cultural adaptation of the treatment program is particularly important in cognitive behavioral therapy for BN. Recently, an internet-based cognitive behavioral therapy (ICBT) program was developed for Japanese women with BN, adapted to the Japanese food culture. However, no previous randomized controlled trial has examined the effectiveness of ICBT.Objective: This paper presents a research protocol for strategies to examine the effects of guided ICBT.Methods: This study is designed as a multicenter, prospective, assessor-blinded randomized controlled trial. The treatment groups will be divided into treatment as usual (TAU) alone as the control group and ICBT combined with TAU as the intervention group. The primary outcome is the total of binge eating and purging behaviors assessed before and after treatment by an independent assessor. Secondary outcomes will include measures of eating disorder severity, depression, anxiety, quality of life, treatment satisfaction, and working alliances. Treatment satisfaction and working alliances will be measured post assessment only. Other measures will be assessed at baseline, post intervention, and follow-up, and the outcomes will be analyzed on an intention-to-treat basis.Results: This study will be conducted at 7 different medical institutions in Japan from August 2022 to October 2026. Recruitment of participants began on August 19, 2022, and recruitment is scheduled to continue until July 2024. The first participants were registered on September 8, 2022.Conclusions: This is the first multicenter randomized controlled trial in Japan comparing the effectiveness of ICBT and TAU in patients with BN.
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| 4. |
- Kobayashi, Yutaka, et al.
(författare)
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Cyclin-dependent kinase 1 is essential for muscle regeneration and overload muscle fiber hypertrophy
- 2020
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Ingår i: Frontiers in cell and developmental biology. - : Frontiers Media SA. - 2296-634X. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Satellite cell proliferation is an essential step in proper skeletal muscle development and muscle regeneration. However, the mechanisms regulating satellite cell proliferation are relatively unknown compared to the knowledge associated with the differentiation of satellite cells. Moreover, it is still unclear whether overload muscle fiber hypertrophy is dependent on satellite cell proliferation. In general, cell proliferation is regulated by the activity of cell cycle regulators, such as cyclins and cyclin-dependent kinases (CDKs). Despite recent reports on the function of CDKs and CDK inhibitors in satellite cells, the physiological role of Cdk1 in satellite cell proliferation remains unknown. Herein, we demonstrate that Cdk1 regulates satellite cell proliferation, muscle regeneration, and muscle fiber hypertrophy. Cdk1 is highly expressed in myoblasts and is downregulated upon myoblast differentiation. Inhibition of CDK1 activity inhibits myoblast proliferation. Deletion of Cdk1 in satellite cells leads to inhibition of muscle recovery after muscle injury due to reduced satellite cell proliferation in vivo. Finally, we provide direct evidence that Cdk1 expression in satellite cells is essential for overload muscle fiber hypertrophy in vivo. Collectively, our results demonstrate that Cdk1 is essential for myoblast proliferation, muscle regeneration, and muscle fiber hypertrophy. These findings could help to develop treatments for refractory muscle injuries and muscle atrophy, such as sarcopenia.
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| 5. |
- Moverare, Johan, 1973-, et al.
(författare)
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A New Single Crystal Superalloy for Power Generation Applications :
- 2011
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Ingår i: Proceeding of the 8th International Charles Parsons TurbineConference 2011. ; , s. G2-2-
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Konferensbidrag (refereegranskat)abstract
- A newly developed single crystal superalloy (known as STAL15) is described which is suitable for use in first stage blades of highly efficient industrial gas turbines (IGTs). With 15 wt% Cr and 4.55 wt% Al, the alloy combines good corrosion and oxidation resistance with sufficient creep and fatigue performance. Thus a novel and useful balance of environmental and mechanical properties is displayed. In this paper, the details of the development project are described. The new alloy is shown to be an alumina (Al2O3) former; the mechanisms behind the Al2O3-formation process are studied and the effects arising from changes in the chemical composition have been modelled. In addition, the mechanical properties in terms of creep and fatigue resistance are evaluated together with the alloy stability during long term (up to 10,000 hours) exposure. For such applications, the new alloy is superior to existing nickel-based single crystal superalloys designed for aero engine applications and which are optimized for very high creep resistance; experience has shown that they are not ideal for use in IGTs of the type used for power generation or mechanical drive, due to their low corrosion resistance. The main reason for this is that IGTs are exposed to more harsh conditions in terms of air quality through the turbine and significantly longer time between overhaul/inspection. Traditionally this has been handled by use of polycrystalline alloys such as IN792 and IN738LC or the single crystal alloy PWA1484; unfortunately these do not form a protective Al2O3 layer and hence display limited resistance to environmental degradation. The new alloy does not display this weakness and is therefore highly optimised for IGT applications.
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| 6. |
- Moverare, Johan, et al.
(författare)
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On Localized Deformation and Recrystallization as Damage Mechanisms during Thermomechanical Fatigue of Single Crystal Nickel-Based Superalloys
- 2011
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Ingår i: Advanced Materials Research. - Switzerland : Trans Tech Publications. - 1022-6680 .- 1662-8985. ; 278:278, s. 357-362
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Tidskriftsartikel (refereegranskat)abstract
- Thermomechanical fatigue (TMF) in superalloys is growing in importance due to the introduction of advanced cooling systems but also due to the changes in demand and competition within the power generation market; this is requiring many power plants to operate under cyclic conditions. In this paper the TMF behaviour of three different single crystal nickel-based superalloys are compared. It is demonstrated that the deformation and damage mechanisms occurring during TMF are rather different from those traditionally reported for creep or isothermal fatigue. In all cases examined, the deformation is localized within a rather small number of deformation bands. While these bands were found to consist mainly of micro-twins in some alloys, in others they might be better described as slip or shear bands. Furthermore, in some circumstances these bands are prone to recrystallization. In CMSX-4, the intersection points of twins of different orientation act as initiation sites for this process. In the SCA425 alloy – of smaller gamma’ content, lower creep resistance and less great oxidation resistance – twinning is observed infrequently; however the deformation is still very localized and in the distorted gamma-gamma’ microstructure, along the shear bands, recrystallization is observed. Furthermore the recrystallization is enhanced by oxidation due to the development of a gamma’-depleted zone. In CMSX-4, TCP phases precipitated during long term ageing cause a more dispersed deformation behaviour which prevents recrystallization. Our findings confirm the importance of an inhomogeneous microstructure for good TMF resistance.
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| 7. |
- Moverare, Johan, et al.
(författare)
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Thermomechanical Fatigue of Single-Crystal Superalloys : Influence of Composition and Microstructure
- 2012
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Ingår i: Superalloys 2012. - Hoboken, NJ, USA : The Minerals, Metals, and Materials Society. - 9780470943205 - 9781118516430 ; , s. 369-377
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Konferensbidrag (refereegranskat)abstract
- The thermomechanical fatigue (TMF) behaviour of a new high Cr-containing single crystal superalloy, known as STAL-15, is investigated. This is a candidate alloy for future industrial gas turbine (IGT) applications. TMF involves complex interactions between high and low temperature deformation mechanism, and this study highlights important factors controlling their interrelationship. Emphasis is placed particularly on the microslructural aspects which control deformation. It is demonstrated that the TMF performance of the new alloy is comparable to that of a second generation alloy such as CMSX-4, despite the absence of Re alloying. An addition of 0.25wt% Si significantly improves the resistance to TMF further; this is attributed to a greater resistance to recrystallization and cracking along the deformation bands that develops across the cross section of the specimen during testing. The TMF resistance increases with increasing primary γ′ size, but the degree of solutioning of the γ′ phase caused by the solution heat treatment seems to have no significant effect.
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| 8. |
- Reed, Roger, et al.
(författare)
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A New Single Crystal Superalloy for Power Generation Applications
- 2012
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Ingår i: Superalloys 2012. - Hoboken, NJ, USA : The Minerals, Metals, and Materials Society. - 9780470943205 - 9781118516430 ; , s. 197-204
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Konferensbidrag (refereegranskat)abstract
- The properties of a newly developed single crystal super alloy-known as STAL-15 - is described which is suitable for use in first stage blades of industrial gas turbines (IGTs). With 15 wt.% Cr and 4.55 wt.% Al, the alloy combines good corrosion and oxidation resistance with sufficient creep and fatigue performance. Traditionally, polycrystalline alloys such as IN792 and 1N738LC or the single crystal alloy PWA-1483 have been used for this application; unfortunately they display only limited resistance to environmental degradation. The new alloy does not display this weakness and is therefore highly optimised for IGT applications. The new alloy is shown to be an alumina (Al2O3) former; the mechanisms behind the Al 2O3-formation process are studied and the effects arising from changes in the chemical composition have been modelled. In addition, the mechanical properties in terms of creep and fatigue resistance are demonstrated together and the alloy stability evaluated during long term (up to 10,000 hours) exposure. For such applications, the new alloy is superior to existing nickel-based single crystal superalloys designed for aeroengine applications and which are optimised for very high creep resistance. The absence of Re contributes to a lower cost of alloy stock, and enhanced castability.
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| 9. |
- Sato, Atsushi, et al.
(författare)
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On the Mechanical Behavior of a New Single-Crystal Superalloy for Industrial Gas Turbine Applications
- 2012
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Ingår i: Metallurgical and Materials Transactions. A. - : Springer. - 1073-5623 .- 1543-1940. ; 43A:7, s. 2302-2315
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Tidskriftsartikel (refereegranskat)abstract
- The mechanical behavior of a new single-crystal nickel-based superalloy for industrial gas turbine (IGT) applications is studied under creep and out-of-phase (OP) thermomechanical fatigue (TMF) conditions. Neutron diffraction methods and thermodynamic modeling are used to quantify the variation of the gamma prime (γ′) strengthening phase around the γ′ solvus temperature; these aid the design of primary aging heat treatments to develop either uniform or bimodal microstructures of the γ′ phase. Under creep conditions in the temperature range 1023 K to 1123 K (750 °C to 850 °C), with stresses between 235 to 520 MPa, the creep performance is best with a finer and uniform γ′ microstructure. On the other hand, the OP TMF performance improves when the γ′ precipitate size is larger. Thus, the micromechanical degradation mechanisms occurring during creep and TMF are distinct. During TMF, localized shear banding occurs with the γ′ phase penetrated by dislocations; however, during creep, the dislocation activity is restricted to the matrix phase. The factors controlling TMF resistance are rationalized.
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| 10. |
- Sato, Atsushi, et al.
(författare)
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On The Oxidation Resistance of Nickel-Based Superalloys
- 2011
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Ingår i: Advanced Materials Research. - Switzerland : Trans Tech Pubications. - 1022-6680 .- 1662-8985. ; 278, s. 174-179
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the factors influencing the oxidation resistance of superalloys are studied. A model is proposed by which the Al2O3-forming properties of a given composition can be estimated, based upon the thermodynamic and kinetic factors influencing scale growth. The numerical modelling is tested by experimental work on a number of compositional variants of the newly-developed SCA425+ superalloy, which contains appreciable quantities of Cr. The modelling is shown to be in broad agreement with experiment. The effects of Al, Cr and Si on the oxidation resistance of this class of alloy have been rationalised.
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