| 1. |
- Wiklund, Urban, et al.
(author)
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Adaptive spatio-temporal filtering of disturbed ECGs: a multi-channel approach to heartbeat detection in smart clothing
- 2007
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In: Medical and Biological Engineering and Computing. - : Springer Science and Business Media LLC. - 1741-0444 .- 0140-0118. ; 45:6, s. 515-523
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Journal article (peer-reviewed)abstract
- Intermittent disturbances are common in ECG signals recorded with smart clothing: this is mainly because of displacement of the electrodes over the skin. We evaluated a novel adaptive method for spatio-temporal filtering for heartbeat detection in noisy multi-channel ECGs including short signal interruptions in single channels. Using multi-channel database recordings (12-channel ECGs from 10 healthy subjects), the results showed that multi-channel spatio-temporal filtering outperformed regular independent component analysis. We also recorded seven channels of ECG using a T-shirt with textile electrodes. Ten healthy subjects performed different sequences during a 10-min recording: resting, standing, flexing breast muscles, walking and pushups. Using adaptive multi-channel filtering, the sensitivity and precision was above 97% in nine subjects. Adaptive multi-channel spatio-temporal filtering can be used to detect heartbeats in ECGs with high noise levels. One application is heartbeat detection in noisy ECG recordings obtained by integrated textile electrodes in smart clothing.
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| 2. |
- Chedid, Michel, 1977-, et al.
(author)
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Experimental Analysis and Modelling of Textile Transmission Line for Wearable Applications
- 2007
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In: International Journal of Clothing Science and Technology. - : Emerald Group Publishing Limited. - 0955-6222 .- 1758-5953. ; 19:1, s. 59-71
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Journal article (peer-reviewed)abstract
- Purpose – By means of measurement and modelling, evaluate frequency dependent per-unit-length parameters of conductive textile transmission line (CTTL) for wearable applications and study deterioration of these parameters when CTTL is subjected to washing. Design/methodology/approach – The studied transmission line is made of Nickel/Copper (Ni/Cu) plated polyester ripstop fabric and is subjected to standard 60oC cycle in a commercial off-the-shelf washing machine. The per-unit-length parameters (resistance and inductance) and characteristic impedance of the line are extracted from measurements before and after washing. Using the measurement data an equivalent circuit is created to model the degradation of the line. The circuit is then integrated in a three-dimensional Transmission Line Matrix (TLM) model of the transmission line. Findings – Both an electrical equivalent circuit and a TLM model are developed describing the degradation of the conductive textile when washed. A severe deterioration of the electrical parameters of the line is noticed. Experimental and modelling results are in good agreement in the addressed frequency band. Research limitations/implications – Analysis is performed for frequencies up to 10 MHz. The developed TLM model can be used to conduct parametric studies of the CTTL. To counteract the degradation of the line, protective coating is to be considered in further studies. Originality/value – Experimental and simulation based characterization of the conductive textile transmission line when subjected to washing cycles.
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| 3. |
- Chedid, Michel, 1977-, et al.
(author)
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Evaluation of Conductive Textile for Wearable Computer Applications
- 2006
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In: The IMAPS Nordic Annual Conference. - 9519800298 ; , s. 220-227
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Conference paper (peer-reviewed)abstract
- Wearable systems put high demands on wearability and robustness. Conductive fabrics are very likely to be used in wearable systems due to their textile-like characteristics. However conductive fabrics must be able to resist environmental stresses (wearing, laundering, etc.) in the same way as clothing in order to fully comply with the requirements. A demonstrator, TxWear, was constructed to exploit conductive fabrics in building a conductive textile transmission line for intermodular communication and power transmission (DC power line communication bus), thus eliminating the need for cables between the modules. The hardware modules are connected to the conductive line through connectors from textile industry, i.e., snap fasteners. Different types of conductive fabrics (Ni/Cu plated polyester fabrics and stainless-steel based elastic ribbon) were evaluated and compared according to their conductivity, flexibility and robustness characteristics. The effect of washing on the electrical properties (per-unit-length parameters) of the textile transmission line was studied. Different coating processes, i.e., parylene and silicone coating, were studied and evaluated in order to isolate and enhance the robustness of the conductive textile. Ni/Cu plated polyester ripstop fabric was found to be not appropriate for wearable applications, while conductive elastic ribbon showed good robustness to laundry induced stresses.
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| 4. |
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| 5. |
- Peterson, Joel, et al.
(author)
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Knittability of fibres with high stiffness
- 2000
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Conference paper (other academic/artistic)abstract
- Knitting techniques and machinery are extensively used for the production of textile products for garmet and industrial use. Knitting is also gaining importance for composite materials performing. Basically two principles are in use. i) Weft knitting gives structures of for example traditional sweaters types suitable for structures taking impact loads. ii) Warp knitting gives the traditional tricot structures and the non crimped insert yarn DOS-fabrics extensively used for composite materials fabrication. In the knitting process do hooked needles pick up yarns and form closed loops. The stability of the loop formation depends on the bending of the fibres and type of friction on the needles during the different stages of the knitting process. The characteristics of static friction when the yarn is drawn by the needles into the machine, sliding friction in the loop formation and release after loop formation are of vital importance for the final product. The complexity of the yarn behaviour, the far from ideal mechanical and tribological behaviour of the fibres are mastered by many knitters. The history of knitting indicate the same kind of phenomena as indicated by the history of the steam engine: ”Science owes more to the steam engine than the steam engine owes to science”, lord Kelvin. The knitting process has however been modelled from first principles using models for friction of fibres on positively curved surfaces and simultaneous plastic deformation. A method and fixtures based on earlier work by Andersson et.al adopted for tests of the stress build up in fibres on knitting needles in order to study the knitting process in a tensile testing machine have been developed. Monofilaments and high modulus multifilament yarns known for giving difficulties in knitting process have been studied with respect to : – Static friction – Bending radius of the fibre during the process – Adhesion to needle at the end contact – Sliding friction Plain knitted fabrics and symmetric spacer fabrics have been produced of monofilament and multifilament nylon, PET and aramides. Analysis of fabrics in compression is going on.
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| 7. |
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| 8. |
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Constitutive Models for Rubber IV : proceedings of the 4th European Conference for Constitutive Models for Rubber, ECCMR 2005, Stockholm, Sweden, 27-29 June 2005
- 2005. - 1
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Editorial collection (peer-reviewed)abstract
- The unique properties of elastomeric materials are taken advantage of in many engineering applications. Elastomeric units are used as couplings or mountings between stiff parts. Examples are shock absorbers, vibration insulators, flexible joints, seals and suspensions etc. However, the complicated nature of the material behavior makes it difficult to accurately predict the performance of these units, using for example finite element modelling. It is therefore necessary that the constitutive model accurately capture relevant aspects of the mechanical behavior. The latest development concerning constitutive modelling of rubber is collected in these proceedings. It is the fourth ECCMR-European Conference on Constitutive Modelling in a series on this subject. Topics included in this volume are, Hyperelastic models, Strength, fracture & fatigue, Dynamic properties & the Fletcher-Gent effect, Micro-mechanical & statistical approaches, Stress softening, Viscoelasticity, Filler reinforcement, and Tyres, fiber & cord reinforced rubber.
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| 9. |
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| 10. |
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| 11. |
- Willander, Magnus, 1948, et al.
(author)
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High-Temperature Electronic Materials: Silicon Carbide and Diamond
- 2007
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In: Springer Handbooks. - Boston, MA : Springer US. ; , s. 537-563
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Book chapter (other academic/artistic)abstract
- The physical and chemical properties of wide-band-gap semiconductors make these materials an ideal wide bandgapsemiconductor choice for device fabrication for applications in many different areas, e.g. light emitters, high-temperature and high-power electronics, high-power microwave devices, micro-electromechanical system (MEM) technology, and substrates for semiconductor preparation. These semiconductors have micro-electromechanical system (MEMS) been recognized for several decades as being suitable for these applications, but until recently the low material quality has not allowed the fabrication of high-quality devices. In this material quality chapter, we review the wide-band-gap semiconductors, silicon carbide and diamond. Silicon carbide electronics is advancing from the research stage to commercial production. The commercial availability of single-crystal SiC substrates during the early 1990s gave rise to intense activity in the development of silicon carbide devices. The commercialization started with the release of blue light-emitting diode (LED). The recent release of high-power Schottky diodes was a further demonstration of the progress made towards defect-free SiC substrates. Diamond has superior physical and chemical properties. Silicon-carbide- and diamond-based diamondsilicon carbide (SiC) electronics are at different stages of development. The preparation of high-quality single-crystal substrates of wafer size has allowed recent significant progress in the fabrication of several types of devices, and the development has reached many important milestones. However, high-temperature studies are still scarce, and diamond-based electronics is still in its infancy.
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| 12. |
- Bergström, Gunnar, et al.
(author)
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The influence from pipe surface, weld beads and protective skins on long term failure times for PE butt fusion joints
- 2004
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In: Plastics Pipes XII.
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Conference paper (peer-reviewed)abstract
- When making creep tensile tests on butt fusion joints in PE pipes almost all failures emerge from the outside of the pipe. Results indicate an influence from the outside surface on the long term behaviour of butt fusion joints. It is a well established practice to scrape the outside surface of PE pipes when making electro-fusion joints. This study stress the question if scraping or bead removal is a positive thing also when making butt fusion joints. Using PE100 pipes butt fusion joints were made using different levels of surface scraping before the butt fusion and with and without removing the weld beads before testing. PE-pipes with an outside PP or PE-skin were also included with and without the skin. Tensile test pieces were cut parallel to the pipe axis centered over the butt fusion joint. The long term strength evaluation were made using a standard accelerated test procedure with the test pieces exposed to a 5 MPa tensile loading immersed in 80 °C water with 2 % Arkopal N100 surfactant. With outside weld beads left intact failure times 200 h to 400 h are normal. Leaving the inner beads but removing the outer beads increase failure times to 1000 h to 2000 h. Failure times for test pieces without weld beads approach 10000 h. Scraping of the pipe surface to a depth of 0.2 mm did not substantially change the failure-time above that for an unscraped surface. Removing 0.7 mm from the pipe surfaceincrease failure times to 2000 h to 3000 h. Outside weld beads and outside pipe surface clearly interact to lower the time to failure in accelerated creep tensile tests. Weld bead removal and scraping of outside pipe surface significantly increase failure times. The exact mechanism is not clear and the implication on butt fusion joint performance in service is not demonstrated but the results indicate possible ways to enhance safety margins when making butt fusion joints. The topic will be given further attention in coming studies.
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| 13. |
- Forsaeus Nilsson, Stefan, 1972, et al.
(author)
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Brittle fracture in casing pipes
- 2006
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In: 10th International Symposium on District Heating and Cooling.
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Conference paper (peer-reviewed)
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| 14. |
- Forsaeus Nilsson, Stefan, 1972
(author)
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Lifetime of HDPE under stress relaxation at large strains
- 2004
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In: Plastics Pipes XII.
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Conference paper (peer-reviewed)abstract
- Slow Crack Growth (SCG) in HDPE under stress relaxation was studied by measuring the time to fracture of notched pipe samples subjected to constant hoop strains. Tests were made in a 2 % Arkopal N-100 tenside solution at various temperatures. The constant deformation was accomplished by pressing the pipe samples onto oversized steel cylinders with diameters giving strain levels ranging from 5 to 50 %. In addition, efforts were made to measure the stress relaxation by applying strain gauges to the steel cylinder wall. Two grades of HDPE were studied—one PE63 grade and one PE100 grade. The two materials were found to behave very differently. Somewhat surprisingly, the PE100 grade generally exhibited shorter fracture times. Furthermore, the time to fracture showed significant temperature dependence but was more or less independent of strain level above the yield point. For the PE63 material, on the other hand, the temperature effect was much less prominent, but a slight strain level dependence was seen. It is likely that the reason for this is differences in the stress relaxation behaviour. As the stress level decreases over time, so does the crack driving potential, and an elevated temperature may not necessarily lead to an overall acceleration of the crack propagation. A frequently used empirical model for the calculation of fracture times was expanded to account for a time dependent stress level. The results indicate that SCG under stress relaxation may be analytically treated in analogy with the more common creep case.
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| 15. |
- Thörnblom, Kristian, 1976, et al.
(author)
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Durability of non-pressure polypropylene pipes
- 2007
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Reports (other academic/artistic)abstract
- For plastics pipes used for underground drainage and sewerage as well as for other nonpressure pipe applications there are at present no internationally accepted methods for the evaluation of the durability of the material. In practice pipe material selection is based upon comparative operational experience of the different materials over a number of years. This means that there are no objective means of assessing new pipe designs and new pipe materials coming onto the market. Reasonably there will be a spread in material qualities with some materials having good properties and some being of lower quality (e.g.recycled materials or materials with very high filler content). Without a recognised testing method it is not possible to rank these alternatives or restrict their use to specific application areas without awaiting the outcome from their use in the field. It is today an established fact that plastics pipes are well suited for underground water and sewer systems due primarily to their flexibility to soil movement and their corrosion resistance. Pipe deflections of up to 10% of the diameter has been shown to be no problem for plastics pipes according to extensive field studies performed by the Teppfa organisation. However, it is also a fact, not so well known, that the stresses in the pipe wall can still be at a relatively high level after 10 or 50 years of use under such conditions. With new pipe structures and possibly lower quality pipe materials, the stresses and strains in the pipe may well exceed the limiting properties of the material and thereby put the reliable function of the pipe system at risk. One main objective of this study has been to look for limiting values of strain for the different materials, above which excessive deformation or failure can occur. The evaluation method presented is based on the use of a range of durability test methods on mainly polypropylene but also on one polyethylene material. The important characteristics studied include the stress relaxation/strainability properties, slow crack growth / notch resistance, thermo-oxidative degradation and environmental stress cracking. The basic properties of the materials are developed by tests on solid wall pipes. The relaxation behaviour of the materials was also modelled and compared using CAED methodology.
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| 16. |
- Juntikka, Rickard, et al.
(author)
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Selection of energy absorbing materials for automotive head impact countermeasures
- 2004
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In: Cellular polymers. - : SAGE Publications. - 0262-4893 .- 1478-2421. ; 23:5, s. 263-297
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Journal article (peer-reviewed)abstract
- Material candidates for energy absorption in head impact countermeasures for automotive applications are evaluated using both quasi-static and dynamic test methods. Ranking of different materials turns out to be difficult since the mechanical response of a material could vary considerably with temperature, especially for polymers. Twenty-eight selected materials, including foams, honeycombs and balsa wood are tested and evaluated. The materials are subjected to a sequence of tests in order to thin out the array systematically. Quasi-static uni-axial compression is used for initial mapping of the selected materials, followed by quasi-static shear and dynamic uni-axial compression. The quasi-static test results show that balsa wood has by far the highest energy absorption capacity per unit weight but the yield strength is too high to make it suitable for the current application. The subsequent dynamic compression tests are performed for strain rates between 56 s(-1) and 120 s(-1) (impact velocities between 1.4 and 3 m/s) and temperatures in the range -20 - 60 degreesC. The test results emphasize the necessity of including both strain rate and temperature dependency to acquire reliable results from computer simulations of the selected materials.
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| 17. |
- Juntikka, Rickard, et al.
(author)
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Weight-balanced drop test method for characterization of dynamic properties of cellular materials
- 2004
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In: International Journal of Impact Engineering. - 0734-743X .- 1879-3509. ; 30:5, s. 541-554
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Journal article (peer-reviewed)abstract
- A novel weight-balanced drop rig used to evaluate the response of cellular materials subject to dynamic compression is presented. The testing method utilizes approximately constant velocity throughout the major part of the compression phase and the results compare well with results from other methods, reported in the literature. The repetitiveness is excellent, the rig is simple and the results are easily extracted. The applicability of the method for determination of elastic modulus is however limited to materials with relatively low stiffness. Accurate modulus measurements for stiff materials at high strain-rates require a very rigid and lightweight test set-up.
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| 18. |
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| 19. |
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| 20. |
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| 21. |
- Brumer, Harry, et al.
(author)
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Cross-Linking Involving a Polymeric Carbohydrate Material
- 2005
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Patent (pop. science, debate, etc.)abstract
- The present invention relates to a method of cross-linking a polymeric carbohydrate material with a second material by means of a soluble carbohydrate polymer and a crosslinking agent. The present invention furthermore relates to the resulting cross-linked material, to uses of the cross-linked material, as well as to a kit comprising the soluble carbohydrate polymer and the cross-linking agent.
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| 22. |
- Hauer, Bernhard, et al.
(author)
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Process for producing polyamines
- 2009
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Patent (pop. science, debate, etc.)abstract
- The present invention relates to a process for the production of a polyamine involving the use of enzymes; in particular to a process performed in aqueous environment; to the polyamines produced by said method; as well as the use of said polyamines for manufacturing paper, for immobilizing enzymes, or for preparing pharmaceutical or cosmetical compositions. The invention also relates to a novel method for in situ regeneration of cofactors NAD(P)+.
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| 23. |
- Hedenqvist, Mikael S.
(author)
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Barrier Packaging Materials
- 2005
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In: Handbook of Environmental Degradation of Materials. - Norwich, NY : William Andrew Inc.. - 9780815515005 ; , s. 547-563
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Book chapter (other academic/artistic)abstract
- This chapter deals with the barriers in packaging materials. Plastic packaging materials offer toughness, lighter weight, and a level of design flexibility that glass and metal cannot meet. They are permeable to gases, vapors, and liquids, and this limits their use to products that do not require the highest barrier protection. Several ways to improve their barrier properties and to make them competitive with glass and metal are discussed. No other material group offers the same huge range in permeability as polymers do. The success in obtaining a packaging material with optimal barrier properties requires knowledge on all levels, from atomistic details to converting and handling properties. The chapter explains the way the introduction of new molecular groups affects the molecular rigidity, the material crystallinity, the interlayer adhesion, and the folding/sealing properties. All these parameters have an impact on the final packaging barrier properties. The important factors that determine and enhance the barrier properties are described with practical examples in packaging. The chapter also discusses the problems associated with selecting packaging materials for food.
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| 24. |
- Inganäs, Olle, et al.
(author)
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Electrochemomechanical devices from polymer conductors and semiconductors
- 2001. - 2
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In: Encyclopedia of materials. - Oxford : Elsevier. - 9780080431529 ; , s. 2531-2535
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Book chapter (other academic/artistic)abstract
- Conjugated polymer (CP) actuators are devices where the volume of a CP material is changed during a change of the state of oxidation or reduction of the polymer. The volume change is extracted as a geo-metrical change in uni- or bimorphs, where the active material may be combined with the passive supporting material. In bimorphs, which have an active layer supported on a passive Ælm, bending of the assembly occurs as the dimensional change is driven by electrochemistry.
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| 25. |
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