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Schlick K, Markus S, Huemer F, Ratzinger L, Zaborsky N, Clemens H, Neureiter D, Neumayer B, Beate AS, Florian S, Martin V, Grundbichler M, Weiss L, Melchardt T, Greil R, Egle A. Evaluation of circulating cell-free KRAS mutational status as a molecular monitoring tool in patients with pancreatic cancer. Pancreatology 2021; 21:1466-1471. [PMID: 34511398 DOI: 10.1016/j.pan.2021.09.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 08/06/2021] [Accepted: 09/04/2021] [Indexed: 12/11/2022]
Abstract
BACKGROUND Pancreatic carcinoma carries a devastating prognosis and is the 4th leading cause for cancer related death in the US and most European countries. Apart from imaging and CA 19-9, pancreatic carcinoma is still lacking reliable markers to assess tumor dynamics and to monitor treatment response over time. The aim of this study was to evaluate the feasibility of cell free tumor-DNA (cft-DNA), respectively KRAS mutation in peripheral blood, detection as a prognostic and predictive value for chemotherapy monitoring. METHODS Serial plasma samples from 42 patients with KRAS mutated pancreatic cancer were prospectively collected and the ctKRAS Mutation Assay (Idylla™, Biocartis, Mechelen, Belgium) of cft-DNA was performed on 29 patients that did not receive curative surgery and went on to palliative chemotherapy. To monitor cft-DNA KRAS mutation levels during treatment quantitative assessment of cft-DNA was performed at baseline and during follow up at predetermined times. RESULTS All 29 patients included in our analyses had a detected KRAS mutation in the tumor biopsy. In almost half (48.2%) of patients a KRAS mutation could also be detected in peripheral plasma. Patients with detectable KRAS mutations before treatment start in plasma had a significantly worse survival (16.8 months vs not reached, p < 0.031 and HR 3.303). Looking for a dynamic assessment of tumor response, we found a statistically significant association between the KRAS mutant ratio from first staging CT scan to basal levels with tumor response or progress (p = 0.014). CONCLUSION Performing KRAS testing from peripheral blood for patients, who have no elevated tumor markers, might be a novel option for treatment monitoring complementing routine imaging techniques.
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Affiliation(s)
- Konstantin Schlick
- 3rd Medical Department with Hematology and Medical Oncology, Hemostaseology, Rheumatology and Infectious Diseases, Paracelsus Medical University, Salzburg, Austria; Salzburg Cancer Research Institute (SCRI), Salzburg, Austria; Laboratory for Immunological and Molecular Cancer Research (LIMCR), Salzburg, Austria; Center for Clinical Cancer and Immunology Trials (CCCIT), Salzburg, Austria
| | - Steiner Markus
- 3rd Medical Department with Hematology and Medical Oncology, Hemostaseology, Rheumatology and Infectious Diseases, Paracelsus Medical University, Salzburg, Austria; Salzburg Cancer Research Institute (SCRI), Salzburg, Austria; Laboratory for Immunological and Molecular Cancer Research (LIMCR), Salzburg, Austria; Center for Clinical Cancer and Immunology Trials (CCCIT), Salzburg, Austria
| | - Florian Huemer
- 3rd Medical Department with Hematology and Medical Oncology, Hemostaseology, Rheumatology and Infectious Diseases, Paracelsus Medical University, Salzburg, Austria; Salzburg Cancer Research Institute (SCRI), Salzburg, Austria; Laboratory for Immunological and Molecular Cancer Research (LIMCR), Salzburg, Austria; Center for Clinical Cancer and Immunology Trials (CCCIT), Salzburg, Austria
| | - Lukas Ratzinger
- 3rd Medical Department with Hematology and Medical Oncology, Hemostaseology, Rheumatology and Infectious Diseases, Paracelsus Medical University, Salzburg, Austria; Salzburg Cancer Research Institute (SCRI), Salzburg, Austria; Laboratory for Immunological and Molecular Cancer Research (LIMCR), Salzburg, Austria; Center for Clinical Cancer and Immunology Trials (CCCIT), Salzburg, Austria
| | - Nadja Zaborsky
- 3rd Medical Department with Hematology and Medical Oncology, Hemostaseology, Rheumatology and Infectious Diseases, Paracelsus Medical University, Salzburg, Austria; Salzburg Cancer Research Institute (SCRI), Salzburg, Austria; Laboratory for Immunological and Molecular Cancer Research (LIMCR), Salzburg, Austria; Center for Clinical Cancer and Immunology Trials (CCCIT), Salzburg, Austria
| | - Hufnagl Clemens
- Department for Neuroinvention, Christian-Doppler-Klinik Universitätsklinik für Neurologie Paracelsus Medical University, Salzburg, Austria
| | - Daniel Neureiter
- Department of Pathology, Paracelsus Medical University Salzburg, Salzburg, Austria
| | - Bettina Neumayer
- Department of Pathology, Paracelsus Medical University Salzburg, Salzburg, Austria
| | | | - Steiner Florian
- Department of Radiology, Paracelsus Medical University Salzburg, Salzburg, Austria
| | - Varga Martin
- Department of Surgery, Paracelsus Medical University Salzburg, Salzburg, Austria
| | - Michael Grundbichler
- 3rd Medical Department with Hematology and Medical Oncology, Hemostaseology, Rheumatology and Infectious Diseases, Paracelsus Medical University, Salzburg, Austria; Salzburg Cancer Research Institute (SCRI), Salzburg, Austria; Laboratory for Immunological and Molecular Cancer Research (LIMCR), Salzburg, Austria; Center for Clinical Cancer and Immunology Trials (CCCIT), Salzburg, Austria
| | - Lukas Weiss
- 3rd Medical Department with Hematology and Medical Oncology, Hemostaseology, Rheumatology and Infectious Diseases, Paracelsus Medical University, Salzburg, Austria; Salzburg Cancer Research Institute (SCRI), Salzburg, Austria; Laboratory for Immunological and Molecular Cancer Research (LIMCR), Salzburg, Austria; Center for Clinical Cancer and Immunology Trials (CCCIT), Salzburg, Austria
| | - Thomas Melchardt
- 3rd Medical Department with Hematology and Medical Oncology, Hemostaseology, Rheumatology and Infectious Diseases, Paracelsus Medical University, Salzburg, Austria; Salzburg Cancer Research Institute (SCRI), Salzburg, Austria; Laboratory for Immunological and Molecular Cancer Research (LIMCR), Salzburg, Austria; Center for Clinical Cancer and Immunology Trials (CCCIT), Salzburg, Austria
| | - Richard Greil
- 3rd Medical Department with Hematology and Medical Oncology, Hemostaseology, Rheumatology and Infectious Diseases, Paracelsus Medical University, Salzburg, Austria; Salzburg Cancer Research Institute (SCRI), Salzburg, Austria; Laboratory for Immunological and Molecular Cancer Research (LIMCR), Salzburg, Austria; Center for Clinical Cancer and Immunology Trials (CCCIT), Salzburg, Austria
| | - Alexander Egle
- 3rd Medical Department with Hematology and Medical Oncology, Hemostaseology, Rheumatology and Infectious Diseases, Paracelsus Medical University, Salzburg, Austria; Salzburg Cancer Research Institute (SCRI), Salzburg, Austria; Laboratory for Immunological and Molecular Cancer Research (LIMCR), Salzburg, Austria; Center for Clinical Cancer and Immunology Trials (CCCIT), Salzburg, Austria.
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Puzzolo E, Zerriffi H, Carter E, Clemens H, Stokes H, Jagger P, Rosenthal J, Petach H. Supply Considerations for Scaling Up Clean Cooking Fuels for Household Energy in Low- and Middle-Income Countries. Geohealth 2019; 3:370-390. [PMID: 32159025 PMCID: PMC7038875 DOI: 10.1029/2019gh000208] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 09/16/2019] [Accepted: 09/30/2019] [Indexed: 05/20/2023]
Abstract
Promoting access to clean household cooking energy is an important subject for policy making in low- and middle-income countries, in light of urgent and global efforts to achieve universal energy access by 2030 (Sustainable Development Goal 7). In 2014, the World Health Organization issued "Guidelines for Indoor Air Quality: Household Fuel Combustion", which recommended a shift to cleaner fuels rather than promotion of technologies that more efficiently combust solid fuels. This study fills an important gap in the literature on transitions to household use of clean cooking energy by reviewing supply chain considerations for clean fuel options in low- and middle-income countries. For the purpose of this study, we consider electricity, liquefied petroleum gas (LPG), alcohol fuels, biogas, and compressed biomass pellets burned in high performing gasifier stoves to be clean fuel options. Each of the clean fuels reviewed in this study, as well as the supply of electricity, presents both constraints and opportunities for enhanced production, supply, delivery, and long-term sustainability and scalability in resource-poor settings. These options are reviewed and discussed together with policy and regulatory considerations to help in making these fuel and energy choices available and affordable. Our hope is that researchers, government officials and policy makers, and development agencies and investors will be aided by our comparative analysis of these clean household energy choices.
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Affiliation(s)
- E. Puzzolo
- Department of Public Health and PolicyUniversity of LiverpoolLiverpoolUnited Kingdom
- Global LPG PartnershipNew YorkUSA
| | - H. Zerriffi
- University of British Columbia, Forest Resources ManagementCanada
| | - E. Carter
- Colorado State University, Civil and Environmental EngineeringUSA
| | | | | | - P. Jagger
- University of Michigan, School for Environment and SustainabilityUSA
| | | | - H. Petach
- U.S. Agency for International DevelopmentWashingtonDCUSA
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Donchev A, Pflumm R, Galetz M, Mayer S, Clemens H, Schütze M. Oxidation Protection of Multiphase Mo-Containing γ-TiAl-Based Alloys under Cyclic Test Conditions. ACTA ACUST UNITED AC 2015. [DOI: 10.1557/opl.2015.160] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTIntermetallic titanium aluminides solidifying via the disordered β-phase are of great interest for several high-temperature applications in automotive and aircraft industries. In this paper the thermocyclic oxidation behavior of three β-solidifying γ-TiAl-based alloys at 800°C and 900°C in air, with and without fluorine treatment, is reported for the first time. The behavior of the well-known TNM alloy (Ti-43.5Al-4Nb-1Mo-0.1B, in at.%) is compared with that of two Nb-free model alloys which contain different amounts of Mo (Ti-44Al-3Mo and Ti-44Al-7Mo, in at.%). During thermocyclic high-temperature exposure in air a mixed oxide scale develops on all three untreated alloys. Small additions of fluorine in the subsurface region of the alloys change the oxidation mechanism from mixed oxide scale formation to alumina at both temperatures. The oxidation resistance of the fluorine treated samples was significantly improved compared to the untreated samples.
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Schwaighofer E, Schloffer M, Schmoelzer T, Mayer S, Lindemann J, Guether V, Klose J, Clemens H. Influence of Heat Treatments on the Microstructure of a Multi-Phase Titanium Aluminide Alloy. ACTA ACUST UNITED AC 2013. [DOI: 10.3139/147.110142] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Abstract
Intermetallic titanium aluminides are employed in aircraft engines and automobile engines because of their low density and excellent high-temperature properties. Today's TiAl-based alloys are multi-phase alloys of a complex structure which mainly consist of γ-TiAl, α2-Ti3Al and low fractions of a βo-TiAl phase. An example of such an alloy is the so-called TNM alloy which exhibit a nominal composition of Ti-43.5Al-4Nb-1Mo-0.1B (in at %). In this alloy, solidification takes place via the β-phase, with the consequence of a fine-grained and nearly segregation-free microstructure. In spite of that, the cast microstructure also contains coarser grains which can act as crack initiators at room temperature and will reduce the deformation capability during tensile tests. Within the framework of this paper, heat treatment studies were conducted on a cast and hot isostatically pressed material with the primary aim of a microstructural homogenization in order to reduce the crack-initiating microstructural components and, hence, increase its fracture elongation at room temperature. In further heat treatments, microstructures with balanced mechanical properties were adjusted.
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Affiliation(s)
- E. Schwaighofer
- Department Metallkunde und Werkstoffprüfung, Montanuniversität Leoben, Franz-Josef-Straße 18, 8700 Leoben, Österreich; E-Mail:
| | - M. Schloffer
- Department Metallkunde und Werkstoffprüfung, Montanuniversität Leoben, Franz-Josef-Straße 18, 8700 Leoben, Österreich; E-Mail:
| | - T. Schmoelzer
- Department Metallkunde und Werkstoffprüfung, Montanuniversität Leoben, Franz-Josef-Straße 18, 8700 Leoben, Österreich; E-Mail:
| | - S. Mayer
- Department Metallkunde und Werkstoffprüfung, Montanuniversität Leoben, Franz-Josef-Straße 18, 8700 Leoben, Österreich; E-Mail:
| | - J. Lindemann
- Lehrstuhl für Metallkunde und Werkstofftechnik, Brandenburgische Technische Universität Cottbus, Konrad-Wachsmann-Allee 17, 03046 Cottbus, Deutschland
| | - V. Guether
- GfE Metalle und Materialien GmbH, Höfener Straße 45, 90431 Nürnberg, Deutschland
| | - J. Klose
- GfE Fremat GmbH, Lessingstraße 41, 09599 Freiberg, Deutschland
| | - H. Clemens
- Department Metallkunde und Werkstoffprüfung, Montanuniversität Leoben, Franz-Josef-Straße 18, 8700 Leoben, Österreich; E-Mail:
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Schloffer M, Schmoelzer T, Mayer S, Schwaighofer E, Hawranek G, Schimansky FP, Pyczak F, Clemens H. The Characterisation of a Powder Metallurgically Manufactured TNM™ Titanium Aluminide Alloy Using Complimentary Quantitative Methods. ACTA ACUST UNITED AC 2013. [DOI: 10.3139/147.110138] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Abstract
In order to be able to use intermetallic titanium aluminide in industrial applications, a quick and affordable method of quantitatively analysing their microstructures is required. In the presented work it was able to demonstrate on a powder metallurgical manufactured TNM™ alloy of nominal composition Ti-43.5Al-4Nb-1Mo-0.1B (at.%), that by electrolytic-polishing and colour etching a quick and cost effective quantitative microstructural analysis may be carried out via light-optical microscopic images. In doing so, the phase fractions and microstructural constituents of the various types of microstructures present are determined using complementary analysing techniques. Both light-optical and scanning electron microscopic images were captured from each of three different types of microstructures. These were then quantitatively evaluated using an image analysis program. The results were compared with those obtained from X-ray diffraction experiments. The possibilities and limits of the quantitative phase evaluation of light-optical microscopic images of colour etched microstructures are also explained and their relationship to the choice of parameters used for the colour etching and electro-polishing operations discussed.
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Affiliation(s)
- M. Schloffer
- Department Metallkunde und Werkstoffprüfung, Montanuniversität Leoben, 8700, Leoben, Österreich
| | - T. Schmoelzer
- Department Metallkunde und Werkstoffprüfung, Montanuniversität Leoben, 8700, Leoben, Österreich
| | - S. Mayer
- Department Metallkunde und Werkstoffprüfung, Montanuniversität Leoben, 8700, Leoben, Österreich
| | - E. Schwaighofer
- Department Metallkunde und Werkstoffprüfung, Montanuniversität Leoben, 8700, Leoben, Österreich
| | - G. Hawranek
- Department Metallkunde und Werkstoffprüfung, Montanuniversität Leoben, 8700, Leoben, Österreich
| | - F.-P. Schimansky
- Helmholtz-Zentrum Geesthacht, Zentrum für Material- und Küstenforschung GmbH, 21502 Geesthacht, Deutschland
| | - F. Pyczak
- Helmholtz-Zentrum Geesthacht, Zentrum für Material- und Küstenforschung GmbH, 21502 Geesthacht, Deutschland
| | - H. Clemens
- Department Metallkunde und Werkstoffprüfung, Montanuniversität Leoben, 8700, Leoben, Österreich
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Schmoelzer T, Liss KD, Rester M, Yan K, Stark A, Reid M, Peel M, Clemens H. Dynamic Recovery and Recrystallization during Hot-Working in an Advanced TiAl Alloy. ACTA ACUST UNITED AC 2013. [DOI: 10.3139/147.110140] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Abstract
Intermetallic TiAl alloys are light-weight high-temperature materials and intended to partly replace Ni based alloys in jet engines. Due to difficult forming operations, component prices are high and limit the possible field of application. During hot-working, recovery and recrystallization effects determine the microstructural evolution and thereby the mechanical properties of the finished part as well as its behavior during deformation. To study the occurring phenomena, in-situ diffraction experiments with high-energy X-rays were conducted. By means of this method, the dominating processes were identified. The results were validated through electron back scatter diffraction experiments.
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Affiliation(s)
- T. Schmoelzer
- Department Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Franz-Josef Straße 18, 8700 Leoben, Austria. E-mails: ,
| | - K.-D. Liss
- Australian Nuclear Science and Technology Organisation, PMB 2 Menai, NSW, Australia. E-mails: ,
| | - M. Rester
- Department Materials Physics, Montanuniversität Leoben, Franz-Josef Straße 18, 8700 Leoben, Austria. E-mail:
| | - K. Yan
- Australian Nuclear Science and Technology Organisation, PMB 2 Menai, NSW, Australia. E-mails: ,
| | - A. Stark
- HZG-Helmholtz Zentrum Geesthacht, Max-Planck Straße 1, 21502 Geesthacht, Germany. E-mail:
| | - M. Reid
- Faculty of Engineering, University of Wollongong, Faculty of Engineering, Northfields Avenue, NSW, 2522 Australia. E-mail:
| | - M. Peel
- European Synchrotron Radiation Facility, BP 220, 38043 Grenoble Cedex 9, France. E-mail:
| | - H. Clemens
- Department Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Franz-Josef Straße 18, 8700 Leoben, Austria. E-mails: ,
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Clemens H, Ammenwerth W, Bartsch J, Pape F, Borges AC, Bauer TT. Platypnoe-Orthodexie-Syndrom: eine seltene Differenzialdiagnose bei Dyspnoe und schwerer Hypoxämie. Pneumologie 2013. [DOI: 10.1055/s-0033-1334592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Bystrzanowski S, Bartels A, Clemens H, Gerling R, Schimansky FP, Dehm G. Creep Behavior and Microstructural Stability of Ti-46Al-9Nb with Different Microstructures. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-842-s7.12] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTIn this paper the creep behavior and the microstructural stability of Ti-46Al-9Nb (in at.%) sheet material were investigated in the temperature range of 700°C to 815°C. The study involves three different types of microstructure, namely fully lamellar with narrow lamellar spacing, duplex and massively transformed. Short-term creep experiments conducted at 700°C and 225 MPa confirmed that the lamellar microstructure with narrow lamellar spacing exhibits a much higher creep resistance when compared to the massively transformed and duplex ones. During longterm creep tests up to 1500 hours stress exponents (in the range of 4.4 to 5.8) and apparent activation energies (of about 4 eV) have been estimated by means of load and temperature changes, respectively. Both, stress exponents and activation energies suggest that under the applied conditions diffusion-assisted climb of dislocations is the dominant creep mechanism. The thermal stability of the different microstructures under various creep conditions has been analyzed by electron microscopy and X-ray diffraction. Our investigations revealed considerable stress and temperature induced microstructural changes which are reflected in the dissolution of the α2 phase accompanied by precipitation of a Ti/Nb - rich phase situated at grain boundaries. This phase was identified as a ω-related phase with B82-type structure. It was shown, that in particular the duplex microstructure is prone to such microstructural instabilities.
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Behr R, Wanner A, Clemens H, Glatz W. Fatigue Crack Growth Characteristics and Fracture Toughness of γ-Tial Base Alloy Sheet Material. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-364-781] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
AbstractRoom temperature tension-tension fatigue crack growth experiments were perfomed on single edge notch specimens of Ti-48Al-2Cr sheet materials produced on industrial scale with different microstructures ranging from near gamma to fully lamellar. Crack extension was monitored using a travelling optical microscope and a DC potential method. Crack paths and fracture surfaces were investigated by SEM. Fracture toughness data were determined by monotonic loading of previously fatigued samples.
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Clemens H, Glatz W, Eberhardt N, Martinz HP, Knabl W. Processing, Properties and Applications of Gamma Titanium Aluminide Sheet and Foil Materials. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-460-29] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTIntermetallic γ-TiAl based alloys (”γ-alloys”) have a great potential to become important materials for advanced applications in aerospace, automotive and related industries. Research and development on γ-alloys have progressed significantly within the last decade. This research has led to a better understanding of the fundamental correlations between alloy composition and microstructure, processing behaviour and mechanical properties. This paper describes the progress in sheet rolling of γ-TiAl based alloys on industrial scale. Employing an advanced hot-rolling process sheets with lengths >1000 mm have been rolled. Furthermore, first results of foil rolling are presented. The mechanical properties of γ-TiAl sheet material with regard to processing route, alloy composition and microstructure are summarized and discussed. Sheet forming by means of superplastic forming and conventional metal forming techniques has successfully been conducted. Different joining techniques have been studied for γ-alloys including solid-state diffusion bonding. The oxidation resistance of γ-alloys is higher than that of Ti-alloys, however, for long-term applications at temperatures >700°C the need for reliable oxidation protective coatings is anticipated. Recent results of cyclic oxidation tests on coated γ-TiAl sheet are presented. Finally, the results of a stability test conducted on a γ-TiAl panel at 750°C are summarized.
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Abstract
ABSTRACTAt room temperature sheets of γ-TiAl exhibit a higher yield stress in the rolling direction than in the transverse direction. Around 700°C the opposite behavior is observed. The texture mainly consists of a modified cube component. The tetragonal c-axis (001) is aligned in the sheet plane transversely to the rolling direction. Taken into account this special texture and the single crystal yield surface of γ-TiAl we conclude that around 700°C the CRSS of super-dislocations is higher than the CRSS of ordinary dislocations. At RT the relation changes to the opposite.
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Bartels A, Bystrzanowski S, Gerling R, Schimansky FP, Kestler H, Weller M, Clemens H. Creep Properties of a High Niobium Containing γ-TiAl Alloy Sheet Material. ACTA ACUST UNITED AC 2011. [DOI: 10.1557/proc-753-bb3.3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
ABSTRACTIn this study Ti-46Al-9Nb (at%) sheet material processed by a powder metallurgical route was examined. Subsequent to hot rolling the sheets were subjected to a stress-relief treatment at 1273K for 3 hours. During this heat treatment a fine-grained near gamma microstructure has been formed. 100 hours tensile creep tests under constant load were carried out at 700°C in rolling direction, transverse direction as well as 45° direction. Using the method of load changes a stress exponent of 4.1 was determined. Furthermore, the apparent activation energy was determined in the temperature range of 715 – 775°C. Both stress exponent and activation energy suggest that diffusion assisted dislocation climb is the dominant creep mode. A comparison of these results with those of so-called conventional or so-called “2nd generation” γ-TiAl based alloys, e.g. Ti-46.5Al-4(Cr,Nb,Ta,B) (at%) and Ti-47Al-4(Cr,Mn,Nb,Si,B) (at%), indicates a significantly better creep resistance and a higher activation energy of the high Nb containing alloy. Additionally, internal friction experiments were conducted in order to analyze the deformation behavior under very small strains at elevated temperatures.
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Schedler B, Huber T, Eidenberger E, Scheu C, Pippan R, Clemens H. Methods to determine the joint strength of C/C to copper joints. Fusion Engineering and Design 2007. [DOI: 10.1016/j.fusengdes.2007.04.037] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Staron P, Cihak U, Stockinger M, Clemens H. Characterization of residual stresses in IN 718 turbine discs by neutron diffraction and finite element modeling. J of Neutron Res 2007. [DOI: 10.1080/10238160802399597] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Schedler B, Friedrich T, Traxler H, Eidenberger E, Scheu C, Clemens H, Pippan R, Escourbiac F. Examination of C/C flat tile mock-ups with hypervapotron cooling after high heat flux testing. Fusion Engineering and Design 2007. [DOI: 10.1016/j.fusengdes.2006.12.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Willumeit R, Schossig M, Clemens H, Feyerabend F. In-vitro interactions of human chondrocytes and mesenchymal stem cells, and of mouse macrophages with phospholipid-covered metallic implant materials. Eur Cell Mater 2007; 13:11-25. [PMID: 17334976 DOI: 10.22203/ecm.v013a02] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
Phospholipid-coatings on metallic implant surfaces were evaluated in terms of adhesion, proliferation and matrix production of skeletal cells, and of macrophage stimulation. The working hypothesis is that mimicking a model biomembrane by phospholipids on surfaces to which cells adhere, the surface recognition by surrounding cells is altered. In this study, 1) mirror-like polished Ti-6Al-7Nb and 2) porous Ti-6Al-4V specimens were covered with the phospholipids POPE (palmitoyl-oleoyl phosphatidyl-ethanolamine) and POPC (palmitoyl-oleoyl phosphatidyl-choline), and the interactions of a) human articular chondrocytes (HAC), b) human mesenchymal stem cells (HMSC), and c) mouse macrophages (RAW 264.7Rpar; were tested in vitro. On POPE-covered polished surfaces adherence of HAC (42% of seeded cells after 2 hrs) and metabolic activity (MTT after 3 days) were reduced, while on porous surfaces 99% HAC adhered, and metabolic activity was significantly increased, compared to respective native surfaces. On both POPE-covered surfaces the chondrocyte phenotype was present. After 3 weeks of chondrogenic differentiation, cartilage matrix production (measuring chondroitin sulphate per HAC number) was significantly increased by about 30% on both POPE-covered metallic surfaces. On both POPC-covered surfaces nearly no adhering and surviving HAC were found. HMSC grown on POPE-covered porous substrates showed osteogenic differentiation by improved osteopontin and collagen I expression in RT-PCR, and osteocalcin fluorescence and bone nodule formation was only detectable on POPE-covered porous surfaces. In contrast to POPC and other phospholipids used as positive controls, POPE did not stimulate the NO production in mouse macrophage cultures. We therefore conclude that a phospholipid coating by POPE shows potential as surface modification for metallic implant materials.
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Affiliation(s)
- R Willumeit
- GKSS Research Center, Max-Planck-Str.1, 21502 Geesthacht, Germany.
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Erlach S, Danoix F, Leitner H, Auger P, Siller I, Clemens H. Precipitation reactions during the early stages of aging in a Ni and Al alloyed martensitic medium carbon steel. SURF INTERFACE ANAL 2007. [DOI: 10.1002/sia.2517] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Leitner H, Clemens H, Höring S, Wanderka N, Banhart J, Staron P, Jamnig B. Characterisation of precipitates in a stainless maraging steel by three-dimensional atom probe and small-angle neutron scattering. ACTA ACUST UNITED AC 2004. [DOI: 10.3139/146.018001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Staron P, Jamnig B, Leitner H, Ebner R, Clemens H. Small-angle neutron scattering analysis of the precipitation behaviour in a maraging steel. J Appl Crystallogr 2003. [DOI: 10.1107/s0021889803000293] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Hüter J, Clemens H, Ogbukagu A. [Single-stage and 2-stage method for subcutaneous mastectomy]. Arch Gynecol 1979; 228:292. [PMID: 485342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Hüter J, Clemens H, Ogbukagu A. [Subcutaneous or subpectoral prosthesis positioning?]. Arch Gynecol 1979; 228:290. [PMID: 485339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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