| 1. |
- Jasechko, S., et al.
(författare)
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Late-glacial to late-Holocene shifts in global precipitation delta O-18
- 2015
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Ingår i: Climate of the Past. - : Copernicus GmbH. - 1814-9324 .- 1814-9332. ; 11:10, s. 1375-1393
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Tidskriftsartikel (refereegranskat)abstract
- Reconstructions of Quaternary climate are often based on the isotopic content of paleo-precipitation preserved in proxy records. While many paleo-precipitation isotope records are available, few studies have synthesized these dispersed records to explore spatial patterns of late-glacial precipitation delta O-18. Here we present a synthesis of 86 globally distributed groundwater (n = 59), cave calcite (n = 15) and ice core (n = 12) isotope records spanning the late-glacial (defined as similar to 50 000 to similar to 20 000 years ago) to the late-Holocene (within the past similar to 5000 years). We show that precipitation delta O-18 changes from the late-glacial to the late-Holocene range from -7.1% (delta O-18(late-Holocene) > delta O-18(late-glacial)) to + 1.7% (delta O-18(late-glacial) > delta O-18(late-Holocene)), with the majority (77 %) of records having lower late-glacial delta O-18 than late-Holocene delta O-18 values. High-magnitude, negative precipitation delta O-18 shifts are common at high latitudes, high altitudes and continental interiors (delta O-18(late-Holocene) > delta O-18(late-glacial) by more than 3 %). Conversely, low-magnitude, positive precipitation delta O-18 shifts are concentrated along tropical and subtropical coasts (delta O-18(late-glacial) > delta O-18(late-Holocene) by less than 2 %). Broad, global patterns of late-glacial to late-Holocene precipitation delta O-18 shifts suggest that stronger-than-modern isotopic distillation of air masses prevailed during the late-glacial, likely impacted by larger global temperature differences between the tropics and the poles. Further, to test how well general circulation models reproduce global precipitation delta O-18 shifts, we compiled simulated precipitation delta O-18 shifts from five isotope-enabled general circulation models simulated under recent and last glacial maximum climate states. Climate simulations generally show better intermodel and model-measurement agreement in temperate regions than in the tropics, highlighting a need for further research to better understand how inter-model spread in convective rainout, seawater delta O-18 and glacial topography parameterizations impact simulated precipitation delta O-18. Future research on paleo-precipitation delta O-18 records can use the global maps of measured and simulated late-glacial precipitation isotope compositions to target and prioritize field sites.
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| 2. |
- Odenberger, Eva-Lis, et al.
(författare)
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Thermo-mechanical sheet metal forming of aero engine components in Ti-6Al-4V : Part 1: Material characterisation
- 2013
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Ingår i: International Journal of Material Forming. - : Springer Science and Business Media LLC. - 1960-6206 .- 1960-6214. ; 6:3, s. 391-402
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Tidskriftsartikel (refereegranskat)abstract
- Ti-6Al-4V is one of the most frequently used titanium alloy in aerospace applications such as for load carrying engine structures, due to their high strength to weight ratio in combination with favourable creep resistance at moderate operating temperatures. In the virtual development process of designing suitable thermo-mechanical forming processes for titanium sheet metal components in aero engine applications numerical finite element (FE) simulations are desirable to perform. The benefit is related to the ability of securing forming concepts with respect to shape deviation, thinning and strain localisation. The reliability of the numerical simulations depends on both models and methods used as well as on the accuracy and applicability of the material input data. The material model and related property data need to be consistent with the conditions of the material in the studied thermo-mechanical forming process. In the present work a set of material tests are performed on Ti-6Al-4V at temperatures ranging from room temperature up to 560°C. The purpose is to study the mechanical properties of the specific batch of alloy but foremost to identify necessary material model requirements and generate experimental reference data for model calibration in order to perform FE-analyses of sheet metal forming at elevated temperatures in Ti-6Al-4V.
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| 3. |
- Harvey, B. P., et al.
(författare)
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Evolution of marine organisms under climate change at different levels of biological organisation
- 2014
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Ingår i: Water. - : MDPI AG. - 2073-4441. ; 6:11, s. 3545-3574
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Tidskriftsartikel (refereegranskat)abstract
- Research to date has suggested that both individual marine species and ecologicalprocesses are expected to exhibit diverse responses to the environmental effects of climatechange. Evolutionary responses can occur on rapid (ecological) timescales, and yet studiestypically do not consider the role that adaptive evolution will play in modulating biologicalresponses to climate change. Investigations into such responses have typically been focusedat particular biological levels (e.g., cellular, population, community), often lackinginteractions among levels. Since all levels of biological organisation are sensitive to globalclimate change, there is a need to elucidate how different processes and hierarchicalinteractions will influence species fitness. Therefore, predicting the responses ofcommunities and populations to global change will require multidisciplinary efforts acrossmultiple levels of hierarchy, from the genetic and cellular to communities and ecosystems.Eventually, this may allow us to establish the role that acclimatisation and adaptation willplay in determining marine community structures in future scenarios.
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| 4. |
- Odenberger, Eva-Lis, et al.
(författare)
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Tool development based on modelling and simulation of hot sheet metal forming of Ti-6Al-4 V titanium alloy
- 2011
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Ingår i: Journal of Materials Processing Technology. - : Elsevier BV. - 0924-0136 .- 1873-4774. ; 211:8, s. 1324-1335
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Tidskriftsartikel (refereegranskat)abstract
- In the aero engine industry alternative manufacturing processes for load carrying aero engine structures imply fabrication. The concept of fabrication involves simple forgings, sheet metals and small ingots of e.g. titanium alloys which are welded together and heat treated. In the concept phase of the product development process, accurate evaluations of candidate manufacturing processes with short lead times are crucial. In the design of sheet metal forming processes, the manual die try out of deep drawing tools is traditionally a time consuming, expensive and inexact process. The present work investigates the possibility to design hot forming tools, with acceptable accuracy at short lead times and with minimal need for the costly die try out, using finite element (FE) analyses of hot sheet metal forming in the titanium alloy Ti-6Al-4 V. A rather straightforward and inexpensive approach of material modelling and methods for material characterisation are chosen, suitable for early evaluations in the concept phase. Numerical predictions of punch force, draw-in and shape deviation are compared with data from separate forming experiments performed at moderately elevated temperatures. The computed responses show promising agreement with experimental measurements and the predicted shape deviation is within the sheet thickness when applying an anisotropic yield criterion. Solutions for the hot forming tool concept regarding heating and regulation, insulation, blank holding and tool material selection are evaluated within the present work.
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| 5. |
- Riesbeck, Kristian, et al.
(författare)
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Expression of hirudin fusion proteins in mammalian cells : A strategy for prevention of intravascular thrombosis
- 1998
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Ingår i: Circulation. - 0009-7322. ; 98:24, s. 2744-2752
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Tidskriftsartikel (refereegranskat)abstract
- Background - Intravascular thrombosis occurs in disorders of diverse pathogeneses, including allograft and xenograft rejection. In this in vitro study, we describe an approach for tethering the specific thrombin inhibitor hirudin to plasma membranes as part of a genetic strategy for regulating intravascular coagulation. Methods and Results - An HLA class I leader sequence was fused with hirudin linked to domains 3 and 4 of human CD4 and intracytoplasmic sequence from either CD4 or human P-selectin. The constructs were transfected into mouse fibroblasts, Chinese hamster ovary (CHO)-K1 cells, immortalized porcine endothelial cells (IPECs), and a pituitary secretory cell line (D16/16). Thrombin binding to the hirudin fusion proteins expressed on fibroblasts and CHO-K1 cells could be blocked by an anti- hirudin monoclonal antibody and by pretreatment of thrombin with either the synthetic tripeptide thrombin inhibitor PPACK or native hirudin. Hirudin expression significantly modified the procoagulant phenotype of IPECs in human plasma, leading to prolongation of clotting times. Hirudin-CD4-P- selectin fusion proteins accumulated in adrenocorticotropic hormone- containing granules in D16/16 cells, with no cell surface expression except on activation with phorbol ester, when hirudin relocated to the outer membrane. Conclusions - Hirudin fusion proteins were expressed on mammalian cells, where they reduced local thrombin levels and inhibited fibrin formation. Regulated expression was achieved on activated cells by use of the cytoplasmic sequence from P-selectin. In vivo, these fusion proteins may prove useful transgenic or gene therapy agents for preventing intravascular thrombosis.
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