Academic literature on the topic 'Component life extension'
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Journal articles on the topic "Component life extension"
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Davidson, M. J., T. J. Jones, D. D. Rosard, and J. R. Scheibel. "Monitoring for Life Extension." Journal of Pressure Vessel Technology 107, no. 3 (August 1, 1985): 255–59. http://dx.doi.org/10.1115/1.3264444.
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Combustion Engineering is under contract to EPRI to develop, construct and implement into a utility boiler a prototype on-line Boiler Stress and Condition Analyzer. The objective of the program is to develop and to demonstrate the analyzer’s potential to optimize the life of critical boiler components. The analyzer has been designed to assist the operator to warn of damaging transients, to optimize boiler start-up/shutdown rates and to accumulate unit operation data for the calculation of component life expenditure. The analyzer has been installed on the 1000-MW oil-fired Consolidated Edison Ravenswood No. 30 unit. This paper will outline the overall program and highlight significant results to date.
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Nahm, Seung Hoon, Chang Min Suh, Min Woo Jung, Jong Yup Kim, and Chang Hwan Yang. "Application of Damage Tolerance Approach for Turbine Disk Life Extension." International Journal of Modern Physics B 17, no. 08n09 (April 10, 2003): 1916–21. http://dx.doi.org/10.1142/s0217979203019873.
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For gas turbine engines, the safe life methodology has historically been used for fatigue life management of failure critical engine components. The safe retirement limit is necessarily determined by a conservative life evaluation procedure, thereby many components which have a long residual life are discarded. The objective of this study is to introduce the damage tolerant design concept into the life management for aircraft engine component instead of conservative fatigue life methodology which has been used for both design and maintenance. The residual lives of turbine disk component under various temperatures and conditions using creep-fatigue crack initiation and growth data were estimated. As the result of analysis, it was confirmed that retirement for cause concept was applicable to the evaluation of residual life of retired turbine disk which had been designed based on the conventional fatigue life methodology.
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Bougaenko, S. E., E. Yu Rivkin, and B. S. Rodchenkov. "Strength Aspects of Safety and Life Extension of RBMK Reactors." Journal of Pressure Vessel Technology 113, no. 2 (May 1, 1991): 141–44. http://dx.doi.org/10.1115/1.2928738.
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RBMK channel power reactors belong to the one-loop boiling water reactors with graphite as a moderator. Equipment, pipelines and core elements are the main components of the coolant recirculation circuit. Analysis in terms of fracture mechanics shows that the circuit elements conform to the “leak-before-break” criterion, with the pipelines and equipment keeping their availability during the whole design operation period. The core is a critical component for the circuit availability.
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Tu, S.-T., and X. Ling. "Interpretation of damage mechanics behaviour of two-bar structures for the life extension of high-temperature components." Journal of Strain Analysis for Engineering Design 38, no. 2 (February 1, 2003): 125–32. http://dx.doi.org/10.1243/030932403321163659.
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The creep damage behaviour of two-bar structures of different dimensions and materials is studied in terms of continuum damage theory. The basic model is used to interpret the effectiveness of life extension measures for complicated structures. It is found that replacement of the more damaged component prior to rupture will result in an optimized life extension efficiency, depending on the geometric or material difference between the damaged and less damaged components. This has potential to provide guidance on the effectiveness of life extension repairs in high-temperature plants.
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Allen, T. R., J. I. Cole, E. A. Kenik, H. Tsai, S. Ukai, S. Mizuta, and T. Yoshitake. "Using fast reactor component evaluation for pressurized water reactor life extension." JOM 51, no. 10 (October 1999): 27–30. http://dx.doi.org/10.1007/s11837-999-0183-7.
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Carter, Jace A., and Tarun Goswami. "Probabilistic Risk Assessment for Life Extension of Turbine Engine Rotors." Metals 12, no. 8 (July 28, 2022): 1269. http://dx.doi.org/10.3390/met12081269.
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Maintaining the component service life beyond its historical limits requires the ability to accurately quantify component reliability and address the uncertainties in material responses. A probabilistic method for predicting the total fatigue life was developed and applied to determine the probability of failure of a Ti-6Al-4V turbine disk component. The total fatigue life incorporates a dual mechanism approach including the crack initiation life and propagation life while simultaneously determining the associated initial flaw sizes. A microstructure-based model was employed to address the uncertainties in material response and relate the crack initiation life with crack size. The propagation life was characterized using both small and large crack growth models to ensure accurate fatigue life prediction. Fatigue life predictions were found to correlate with experimental data at high stress levels. The risk assessment can be used to estimate the expected initial crack sizes from variability in material properties, which can further be used to establish an enhanced inspection planning.
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Woo, Chang Su, Wan Doo Kim, and Jae Do Kwon. "Fatigue Life Evaluation of Rubber Components for Automobile Vehicles." Key Engineering Materials 324-325 (November 2006): 181–84. http://dx.doi.org/10.4028/www.scientific.net/kem.324-325.181.
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The interest of the fatigue life for rubber components was increasing according to the extension of warranty period of the automotive components. In this study, the fatigue lifetime prediction methodology of the vulcanized natural rubber was proposed by incorporating the finite element analysis and fatigue damage parameter determined from fatigue tests. Finite element analysis of 3D dumbbell specimen and rubber component was performed based on a hyper-elastic material model determined from the mechanical tests. The Green-Lagrange strain at the critical location determined from the finite element analysis was used for evaluating the fatigue damage parameter of the natural rubber. Fatigue tests were performed using the 3D dumbbell specimens and rubber component with different levels of maximum strain and various load. Fatigue life curves can be effectively represented by a following single function using the maximum Green-Lagrange strain. Fatigue lives of the natural rubber are predicted by using the fatigue damage parameters at the critical location. Predicted fatigue lives of the rubber component for automobile vehicle agreed fairly with the experimental fatigue lives.
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Aitken, R. R., D. P. W. Horrigan, and G. Moltschaniwskyj. "Life extension of impact damaged honeycomb sandwich panels." Aeronautical Journal 104, no. 1041 (November 2000): 509–16. http://dx.doi.org/10.1017/s0001924000017887.
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Abstract The assessment of damage due to impacts in composite sandwich panels and the component life reductions associated with such damage is becoming increasingly important within the aerospace industry. This study analyses minimum gauge, non-metallic honeycomb wing panels subject to impact damage. In all instances the damage is caused by ‘soft body’ impactors travelling at elevated velocities to simulate bird strike and other soft debris. The damage formed during these impacts is shown to be large in plan area but shallow and primarily causes crushing of the core in a thin layer. Loading of the panels after impact has been performed to determine the reduction in load carrying capacity and associated failure mechanisms. Damage due to soft body impact is shown to be very different to the classical rigid body impact upon which current repair schemes are based. As a result in many applications the use of current repair schemes may be inappropriate. The viability of new repair techniques is discussed with particular attention to the prevention of failure mechanisms due to loading after impact.
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Yi, Siliang, and Chih-Fu Wu. "Green-Extension Design—A New Strategy to Reduce the Environmental Pressure from the Existing Consumer Electronics." International Journal of Environmental Research and Public Health 18, no. 18 (September 12, 2021): 9596. http://dx.doi.org/10.3390/ijerph18189596.
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Existing electronic devices will quickly become e-waste when encountering technological iterations, which results in serious environmental and public health problems. Previous circular economy research has mainly focused on the development of new products with long life or recycling discarded products. This study firstly proposes the Green-Extension Design (GED) strategy for developing adaptable accessories that provide existing products with the ability to continue to work in a different context. Competitiveness was selected to evaluate the performance of GED, and three competitiveness components were derived through principal component analysis (PCA). Moreover, AHP (Analytic Hierarchy Process) was applied to define the weights of the three competitiveness components, and a GED model was established on the basis of production function. Furthermore, the calculation method for each competitiveness component was defined. The GED strategy is aimed at extending the life of existing products, as well as reducing resource waste and environmental pollution. The GED model based on competitiveness components can enable enterprises to design products of high competitiveness and obtain market share as a result.
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Lawand, Lydia, Khalil Al Handawi, Massimo Panarotto, Petter Andersson, Ola Isaksson, and Michael Kokkolaras. "A Lifecycle Cost-Driven System Dynamics Approach for Considering Additive Re-Manufacturing or Repair in Aero-Engine Component Design." Proceedings of the Design Society: International Conference on Engineering Design 1, no. 1 (July 2019): 1343–52. http://dx.doi.org/10.1017/dsi.2019.140.
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AbstractAero-engine component design decisions should consider re-manufacturing and/or repair strategies and their impact on lifecycle cost. Existing design approaches do not account for alternative production technologies such as the use of additive manufacturing in life extension processes. This paper presents a modeling and optimization methodology for examining the impact of design decisions in the early development stage on component lifecycle cost during the in-service phase while considering the potential use of additive manufacturing in life extension strategies. Specifically, a system dynamics model is developed to assess different end-of-life scenarios. Finally, an optimization problem is formulated and solved to minimize lifecycle cost with respect to design variables related to re-manufacturing.
Dissertations / Theses on the topic "Component life extension"
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Hohmann, Brian P. (Brian Patrick). "Life extension of structural components via an improved nondestructive testing methodology." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/62688.
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Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2010.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 337-355).
An experimental study was performed to determine the flaw detection sensitivity of advanced nondestructive testing (NDT) techniques with respect to structural applications. The techniques analyzed exemplify the incorporation of digital technology into NDT and includes the following: meandering winding magnetometer array (MWM-array@) eddy current, phased-array ultrasonic (PA-UT), three dimensional computed tomography (3DCT), and digital radiography (DR). The three classes of samples inspected with these techniques consisted of alloy block specimens containing flat bottom hole (FBH) arrays, probability of detection (POD) wedding cake samples, and actual airplane engine components. Results from the sensitivity analyses were compared to current NDT techniques used industrially. An image analysis program called Cellprofiler was used to optimize the threshold correction factor for selected results. The Cellprofiler output was analyzed in conjunction with POD software, and the integration of digitally advanced NDT techniques with image analysis software resulted in approximately a threefold improvement in the minimum detectable flaw size at the 90/95 POD/CL level. An improved inspection methodology was presented which incorporated redundancy in the in-service inspection plan with the use of Bayesian updating techniques to forecast remnant life. Reliability block diagrams for structural disk and blade aircraft engine components were presented as examples of the methodology. Implementation of the proposed NDT methodology significantly increases the feasibility of a retirement-forcause (RFC) approach to be applied to aging structural components in a cost-effective manner.
by Brian P. Hohmann.
Sc.D.
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Spradlin, Thomas Joshua. "Process Sequencing for Fatigue Life Extension of Large Scale Laser Peened Components." Wright State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=wright1316292716.
Full textBooks on the topic "Component life extension"
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V, Bicego, Nitta A, Viswanathan Ramaswamy, Comité de Informática do Setor de Energia Elétrica., and Gruppo italiano frattura, eds. Materials ageing and component life extension. Warley: Engineering Materials Advisory Services, 1995.
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Naus, D. Concrete component aging and its significance relative to life extension of nuclear power plants. Washington, D.C: U.S. Nuclear Regulatory Commission, Office of Nuclear Regulatory Research, 1986.
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N, Shah Vikram, and MacDonald Philip E, eds. Aging and life extension of major light water reactor components. Amsterdam: Elsevier, 1993.
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V, Narayanan T., American Society of Mechanical Engineers., and Nihon Kikai Gakkai, eds. Life assessment and life extension of power plant components--1989: [papers] presented at the 1989 ASME Pressure Vessels and Piping Conference, Honolulu, Hawaii, July 23-27, 1989. New York, N.Y. (345 E. 47th St., New York 10017): American Society of Mechanical Engineers, 1989.
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Pressure Vessels and Piping Conference (1992 New Orleans, La.). Nuclear plant systems/components aging management and life extension: Presented at the 1992 Pressure Vessels and Piping Conference, New Orleans, Louisiana, June 21-25, 1992. New York: American Society of Mechanical Engineers, 1992.
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Pressure, Vessels and Piping Conference (1988 Pittsburgh Pa ). Life extension and assessment: Nuclear and fossil power-plant components : presented at the 1988 ASME Pressure Vessels and Piping Conference, Pittsburgh, Pennsylvania, June 19-23, 1988. New York, N.Y. (345 E. 47th St., New York 10017): American Society of Mechanical Engineers, 1988.
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Viswanathan, R. Damage Mechanisms and Life Assessment of High-Temperature Components. ASM International, 1989. http://dx.doi.org/10.31399/asm.tb.dmlahtc.9781627083409.
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Damage Mechanisms and Life Assessment of High-Temperature Components deals with the underlying causes of high-temperature failures and their effect on component life and reliability. The first few chapters develop the theory necessary to understand and analyze high-temperature damage phenomena, including fracture, creep, and fatigue. Various forms of embrittlement and corrosion are also addressed as are creep-fatigue, thermal fatigue, and welding defects. The chapters that follow discuss the practical implications of these phenomena, explaining how to assess damage and estimate the remaining service life of boiler tubes, turbine blades, reactor vessels, nozzles, and other components. Life-assessment procedures draw on a knowledge of design, material behavior, and nondestructive inspection techniques, which are covered as well. The book makes extensive use of data plots, diagrams, and images and includes many worked-out examples and case histories. It also serves as a ready source of material property data. For information on the print version, ISBN 978-0-87170-358-3, follow this link.
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Jaske, C. Life Extension and Assessment Nuclear and Fossil Power Plant Components/Conference Proceedings Pittsburgh, Pa. June 1988.Asme Pvp Vol. 138 Nde Vol. 4. Amer Society of Mechanical, 1988.
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J, Sinnappan, American Society of Mechanical Engineers. Pressure Vessels and Piping Division., and Pressure Vessels and Piping Conference (1991 : San Diego, Calif.), eds. Power plant systems/components aging management and life extension, 1991: Presented at the 1991 Pressure Vessels and Piping Conference, San Diego, California, June 23-27, 1991. New York, N.Y: American Society of Mechanical Engineers, 1991.
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Kissane, David W., Annette F. Street, Erin E. Schweers, and Thomas M. Atkinson. Research into psychosocial issues. Oxford University Press, 2015. http://dx.doi.org/10.1093/med/9780199656097.003.0195.
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Psychological, existential, spiritual, and social issues cause much suffering and deserve extensive study to understand these concerns more fully and to intervene more effectively. Themes that abound include communication, coping, ethics, the family, caregiving, quality of life, death and dying, psychiatric disorders, suffering, and the many expressions of distress. Many study designs are possible to explore these themes, often with complementary quantitative and qualitative components. This chapter summarizes the psychometric properties of many of the instruments that are commonly employed in such studies and the computer-assisted software packages that assist qualitative analyses. The goal is to strengthen research design and optimize research outcomes to benefit the discipline.
Book chapters on the topic "Component life extension"
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Cakmak, Hulya, and Ece Sogut. "Functional Biobased Composite Polymers for Food Packaging Applications." In Reactive and Functional Polymers Volume One, 95–136. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-43403-8_6.
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AbstractBiobased polymers are of great interest due to the release of tension on non-renewable petroleum-based polymers for environmental concerns. However, biobased polymers usually have poor mechanical and barrier properties when used as the main component of coatings and films, but they can be improved by adding nanoscale reinforcing agents (nanoparticles - NPs or fillers), thus forming nanocomposites. The nano-sized components have a larger surface area that favors the filler-matrix interactions and the resulting material yield. For example, natural fibers from renewable plants could be used to improve the mechanical strength of the biobased composites. In addition to the mechanical properties, the optical, thermal and barrier properties are mainly effective on the selection of type or the ratio of biobased components. Biobased nanocomposites are one of the best alternatives to conventional polymer composites due to their low density, transparency, better surface properties and biodegradability, even with low filler contents. In addition, these biomaterials are also incorporated into composite films as nano-sized bio-fillers for the reinforcement or as carriers of some bioactive compounds. Therefore, nanostructures may provide antimicrobial properties, oxygen scavenging ability, enzyme immobilization or act as a temperature or oxygen sensor. The promising result of biobased functional polymer nanocomposites is shelf life extension of foods, and continuous improvements will face the future challenges. This chapter will focus on biobased materials used in nanocomposite polymers with their functional properties for food packaging applications.
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Coffin, L. F. "Damage Evaluation and Life Extension of Structural Components." In Advances in Fatigue Science and Technology, 727–46. Dordrecht: Springer Netherlands, 1989. http://dx.doi.org/10.1007/978-94-009-2277-8_33.
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Campion, R. P. "Methodologies for Service Life Predictions of Elastomeric Components in Oilfield Engineering." In Ageing Studies and Lifetime Extension of Materials, 545–51. Boston, MA: Springer US, 2001. http://dx.doi.org/10.1007/978-1-4615-1215-8_61.
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Ishii, Jun, Yoichi Hiramatsu, and Kazuhiro Funato. "Novel Repair Technique for Life-Extension of Hydraulic Turbine Components in Hydroelectric Power Stations." In Challenges of Power Engineering and Environment, 551–57. Berlin, Heidelberg: Springer Berlin Heidelberg, 2007. http://dx.doi.org/10.1007/978-3-540-76694-0_102.
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Jeannet, Jean-Pierre, Thierry Volery, Heiko Bergmann, and Cornelia Amstutz. "Product Line Choices." In Masterpieces of Swiss Entrepreneurship, 177–81. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-65287-6_17.
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AbstractSuccess in global markets is not only dependent on the quality and effectiveness of a single product. For many firms, even as they focus on narrow niches, the number of product variations they can cram into a narrow market space becomes a competitive advantage. How SMEs dealt with requirements for product line depth vs. breadth and, in particular, how they managed to use platforming and modularity to maximize product variations to increase the number of SKUs offered in their chosen market space. To enable such market cramming, companies have adopted extensive modularization strategies to create a maximum of product variations from a limited set of components. Platforming is another method companies use to create multiple variations from a single platform which is more efficient to produce and market. The combination of both modularization and platforming is allowing this game to be played to an even greater extent, permitting a small company to become a relative giant in a small space.
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Ocaña, José-Luis, Ángel García-Beltrán, Carlos Correa, Juan-Antonio Porro, Leonardo Ruiz-de-Lara, and Marcos Díaz. "Computer-Aided Development of Thermo-Mechanical Laser Surface Treatments for the Fatigue Life Extension of Bio-Mechanical Components." In Lecture Notes in Computer Science, 429–38. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-18833-1_45.
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Shmidt, Victoria. "Vitalist Arguments in the Struggle for Human (Im)Perfection: The Debate Between Biologists and Theologians in the 1960s–1980s." In History, Philosophy and Theory of the Life Sciences, 217–38. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-12604-8_12.
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AbstractIn this chapter, I explore and offer critical reflections on the widespread practice of attributing negative value to “vital forces” in debates on health and disease, as the direct result of the extensive dissemination of genetics and its implications since the late 1960s. This historical reconstruction focuses on the most heated debates in popular science periodicals and editions, having the longest-lasting public “echo,” which have shaped an intergenerational continuity in the reproduction of vitalist arguments in discursive practices regarding health, disease, and their genetic factors.Mapping attacks on vital forces as various forms of negation addresses three different debates in the historically interrelated repertoire of potentially rival approaches to health, disease, and their genetic components: (1) the attribution of negative value to primal instinct as an obstacle to the progress of human civilization; (2) the normative vitalism mainly associated with French philosophers George Canguilhem, Michel Foucault, and Gilles Deleuze; and (3) the movement for the deinstitutionalization of health care within the negative theology presented by Ivan Illich.The reproduction of vitalist arguments in the each of the three realms is seen as a historical continuity of the medical vitalism that appeared in the Enlightenment and that produced a less monolithic and more conceptually coherent continuum of the positions regarding health, diseases, and their causes. In line with the Lakatosian division into internalist and externalist histories of science, I focus on the multiple functions of vitalist arguments: as a main force in the contest among rival theories regarding health and disease (as a part of the internalist narrative); as a signifier of the boundary work delineating science and not-science, whether labeled as theology or as “bad” science aimed at legitimizing science (as a part of externalist history); and as an ideological platform for bridging science and its performance in policies concerning reproduction .
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Caprani, C., J. Ghosh, and J. Padgett. "Influence of live loads on component and system level highway bridge seismic fragility." In Bridge Maintenance, Safety, Management and Life Extension, 718–25. CRC Press, 2014. http://dx.doi.org/10.1201/b17063-105.
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Song, Hao, and Suqin Wang. "Production Riser Life Extension – A Class Perspective." In Ageing and Life Extension of Offshore Facilities, 56–63. ASME, 2022. http://dx.doi.org/10.1115/1.885789_ch5.
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Risers are a critical element in subsea production systems for transporting hydrocarbons from the seafloor to the surface. Many subsea production risers are approaching the end of their original design life (e.g. 20 or 25 years); therefore, they need to be either decommissioned or entered into in a life extension process. Due to enhanced recovery and tiebacks from adjacent fields, more and more existing fields are continuing to produce. As a result, the life extension of those offshore assets including production risers has become a viable solution. For a riser’s life extension application, the process generally includes three phases: investigation, determination, and implementation. Baseline surveys and data collection should be performed during the investigation phase. A riser’s life extension requires a life extension assessment created from collected riser characteristic data, condition data, and operating data to confirm the riser’s integrity and its capacity for extended operations under future operating conditions. The life extension assessment may confirm that the riser is fit-for-service in its present condition for the planned extended service life, or call for a plan with repairs, component replacements, additional inspections, additional monitoring, or a combination of these. An application for riser life extension is usually required to be submitted to the local Authority (if applicable) for approval. Owners and operators generally require the review of the riser life extension by an independent third party (I3P). The earlier the I3P/CVA engages in the process, the better the readiness of the life extension application. Currently, industry experience on production riser life extension is limited, and safety of aging production risers is a major focus of the industry. This paper addresses the technical recommendations and guidance from a Class perspective on life extension for subsea production risers attached to floating production installations that produce and/or store hydrocarbons. The same process and methodology are also applicable to injection risers and import/export risers. The technological challenges associated with riser life extensions are highlighted. Special cases of the riser life extension in Gulf of Mexico (GoM) and risers managed in an integrity management program are also demonstrated.
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DOMAZET, Ž. "LIFE EXTENSION OF FATIGUE DAMAGED COMPONENTS." In Advances in Fracture Research, 415–21. Elsevier, 1997. http://dx.doi.org/10.1016/b978-0-08-042820-8.50050-9.
Full textConference papers on the topic "Component life extension"
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Cooke, Lloyd A. "Component Management Programs for Reliable Life Extension." In ASME Turbo Expo 2001: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/2001-gt-0431.
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Conventional maintenance schedules and scheduling techniques are typically based on the manufacturer’s guidelines and applied to all engines of a certain make and model. This approach does not always address the specific operating environment and requirements for each operator. An alternative to this conventional “one schedule suits all” approach is the Component Management Program described in the paper. This type of program is designed to tailor maintenance requirements to suit the specific operating environment of the operator’s engine or fleet of engines. The program is intended to extend and optimize maintenance intervals and at the same time ensure reliability of the components. The paper outlines the metallurgical analysis and other techniques that are incorporated into a Component Management Program, the tracking systems used to schedule maintenance, and some case studies where these programs have been used to extend component life and reliability.
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Liburdi, J., and P. Lowden. "Enabling Technologies for Advanced Turbine Component Life Extension." In ASME 1999 International Gas Turbine and Aeroengine Congress and Exhibition. American Society of Mechanical Engineers, 1999. http://dx.doi.org/10.1115/99-gt-445.
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The evolution in materials and turbine design has resulted in the parallel development of advanced equipment and processes capable of manufacturing and repairing critical engine components. Modern, vision based automated welding systems are now widely utilized for precise, low heat welding of crack sensitive alloys. Unique powder metallurgy processes such as LPM™ allow repairs to be engineered for higher localized strength or better wear properties for applications such as abrasive tips. Significant changes have also occurred in the stripping and coating processes with the introduction of sophisticated vapour-based technologies. These advanced technologies are extending opportunities for repair and life extension of turbine components, but the availability and costs associated with these enabling technologies, along with the difficulty in obtaining approvals, may restrict sources for advanced component repairs.
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Yetisir, M., G. L. Stevens, and S. Robertson. "Management of Component Fatigue in CANDU Stations for Life Extension." In 16th International Conference on Nuclear Engineering. ASMEDC, 2008. http://dx.doi.org/10.1115/icone16-48757.
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CANDU® nuclear generating stations and their components were designed for 30 effective full power years (EFPY) of operation. Many CANDU plants are now approaching their design end-of-life and are being considered for extended operation beyond their design life. The Canadian regulator, the Canadian Nuclear Safety Commission (CNSC), has asked utilities to consider component fatigue issues in plant life extension (PLEX) applications. In particular, environmental effects on fatigue is identified as an issue that needs to be addressed, similar to that being addressed for license renewal for U.S. nuclear power plants. To address CNSC concerns, CANDU stations have initiated a program to develop component fatigue management programs for PLEX operation. A pilot study conducted in a typical CANDU plant showed that: • Only 10 to 15% of the numbers of design transients have been used after 25 EFPY of operation. Hence, a significant amount of original design fatigue usage margin remains available for PLEX operation. • Environmental fatigue considerations in heavy water (D2O) were included in the assessment. Only warm-up transients are assessed to have dissolved oxygen concentrations that can result in a significant environmental effect for the ferritic steels used in the CANDU primary and secondary systems. • Due to the low accumulation of transients, and the relative absence of thermal stratification mechanisms, thermal fatigue is not as significant an issue in CANDU plants as in pressurized water reactor (PWR) and boiling water reactor (BWR) plants. This paper summarizes the results of the pilot study conducted for the Canadian CANDU plants.
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Macheret, Yevgeny, and Leo Christodoulou. "Impact of Prognosis on Asset Life Extension and Readiness." In ASME 2003 International Mechanical Engineering Congress and Exposition. ASMEDC, 2003. http://dx.doi.org/10.1115/imece2003-42391.
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Fatigue response of structural components is determined by environmental conditions, material microstructure, and loading history. Variation of these factors results in significant scatter in fatigue-crack growth rates and component life. In this paper, the impact of prognosis capability on asset life extension and readiness is evaluated. Fatigue-crack growth data on aluminum samples under controlled spectrum loading are used to describe the statistics of the crack-size distribution. Several sensors with different probability of detection (POD) characteristics are considered for detecting cracks of critical size, and the effect of the POD on the component life extension is evaluated. Although the crack-detection capability leads to the asset life extension, it is not sufficient to maintain required mission readiness. On the other hand, the prognosis capability, which is based on the knowledge of the component’s current damage state, damage evolution laws, and upcoming mission loading, allows required mission readiness to be maintained.
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Gong, Wenjun, Yunxia Chen, Yi Yang, and Rui Kang. "Economic life prediction of repairable multi-component systems based on extension theory." In 2016 IEEE International Conference on Industrial Engineering and Engineering Management (IEEM). IEEE, 2016. http://dx.doi.org/10.1109/ieem.2016.7797927.
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Minas, Constantinos, and Mark E. Vermilyea. "Life Extension of an X-Ray Tube Target." In ASME 1998 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1998. http://dx.doi.org/10.1115/imece1998-0372.
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Abstract A methodology for the life extension of an X-Ray target was developed. X-Ray tube targets are rotating axisymmetric multi-component components used in X-Ray tubes of medical equipment. An X-Ray target is subjected to extreme cyclic thermal loading conditions based on the imaging system requirements. A very complex, time dependent stress state is present in such targets because of the combination of processing and utilization. Residual stresses are present following initial target assembly and heat treatment required to establish and maintain the high vacuum required in the X-Ray tube. In addition, cyclic stresses arise from the imaging protocols. The factors controlling these stresses include the thermal expansion coefficients of the various materials, the temperature distributions and the geometry of the components. The proposed methodology for the life extension of an X-Ray target included the development of an integrated thermal and structural axisymmetric finite element model. The combined thermal structural model was initially used to evaluate the severity of the various thermal protocols a target is subjected to. The structural analysis was carried out in the plastic regime, since typical stresses exceeded the yield stress of the materials used. Design of experiment (DOE) studies were carried out in order to evaluate the influence of geometric quantities on the resultant temperature distribution and thermal stresses. Tolerances of geometric quantities were applied to reflect manufacturing inaccuracies. An optimal design was selected for which the equivalent plastic strains were minimized. The effect of the manufacturing tolerances on the optimal solution was also examined.
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Anandapadmanaban, B., A. Babu, B. Babu, K. Dinesh, V. Ramanathan, and G. Srinivasan. "Life Extension of the Fast Breeder Test Reactor." In 18th International Conference on Nuclear Engineering. ASMEDC, 2010. http://dx.doi.org/10.1115/icone18-29277.
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The Fast Breeder Test Reactor (FBTR) is a loop type sodium cooled fast reactor located at Kalpakkam, India. The reactor went critical in October, 1985 with a core of 23 unique high Plutonium carbide fuel subassemblies and the reactor power was rated for 10.5MWt with peak linear heat rating of fuel at 320W/cm. The extension of the target burn-up of this fuel based on Post Irradiation Examination at different stages enabled progressive expansion of the core and increase in reactor power. The reactor has been operated upto a power level of 18.6MWt/3MWe with a sodium temperature of 482°C max. The reactor has completed 24 years of operation and is currently under periodic safety review by the Atomic Energy Regulatory Board of India. As a part of the periodic safety review, equipment qualification status and ageing management studies have been presented to the regulators. Equipment qualification refers to the ability of the replaceable equipment to meet the functional requirements on demand, accomplished by periodic surveillance, maintenance and replacement. Ageing management addresses the residual life assessment of components which are passive, non-replaceable / replaceable with difficulty, taking into account their life degrading mechanisms. Over a period of time, based on the operational feedback, maintenance difficulties and obsolescence, several major components have been replaced. These include the Neutronic channels, UPS, computers of the Central Data Processing System, main boiler feed pumps, three control rod drive mechanisms, two control rods, central canal plug, deaerator lift pumps, reheaters of the steam water system, station batteries, DM plant and Nitrogen plant. The starting air system of the emergency diesel generators and isolation dampers of the reactor containment building have also been replaced. Regarding the non-replaceable components, residual life assessment has been carried out based on the operational history vis-a`-vis the design limits for each component. The life limiting mechanism of heat transport systems of FBTR are creep and fatigue. Since the reactor has operated only upto a temperature of 444°C till 2007, the creep effect is insignificant. The total number of thermal cycles seen by the reactor components as of 2007 was 163, as against the design cycle of 2000 for most of the components. Hence all the heat transport system components are as good as fresh ones. However, the major life limiting factor has been found to be the Neutronic fluence on the grid plate which supports the core. The fast flux at the grid plate location was measured using Np foils and the residual life of the reactor has been assessed to be 10.5 effective full power years. This paper details the life extension exercise being carried out for FBTR.
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Vicencio, Mario. "Proposed Concept of Service Life Extension of Marine Propulsion Shafts." In SNAME 9th Propeller and Shafting Symposium. SNAME, 2000. http://dx.doi.org/10.5957/pss-2000-10.
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Marine propeller shafts, like most power transmission shafts, are fatigue-loaded components. Because of the corrosive environment, they operate in, a marine propeller shafts' corrosion fatigue strength may the limiting factor in its design. The life of a fatigue-loaded mechanical component is dependent on the tensile stresses it is subjected to in service. If effective tensile stresses acting on a shaft could be reduced. Service life could be extended Shot Peening is a mature, developed procedure that has been proven successful in raising fatigue strength and retarding Stress Corrosion Cracking. A rather simplified approach explaining how and why it works in addressing the very complicated subject of fatigue is presented here. Particularly in the aerospace and automotive industries, its successful applications are well documented The practical suggestion on how it could be applied in providing extended service lives for marine propeller shafts is attempted in this paper. Several relevant case studies conducted by other researchers are presented.
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Bohrenkämper, Gerhard, Herbert Bals, Ursel Wrede, and René Umlauft. "Hot-Gas-Path Life Extension Options for the V94.2 Gas Turbine." In ASME Turbo Expo 2000: Power for Land, Sea, and Air. American Society of Mechanical Engineers, 2000. http://dx.doi.org/10.1115/2000-gt-0178.
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Gas turbine and combined cycle power plants are typically designed for a service life of over 30 years. If operated at base load in continuous duty, the gas turbine hot-gas-path components for example in a combined-cycle power plant need repair and replacement according to the maintenance program several times during plant life. Most of the hot components would reach the end of their service life, e.g. 100,000 equivalent operating hours (EOH), after 10 to 12 years. As this is well before the end of the overall plant service life defined in the power plant concept, such plant applications therefore necessitate life extension measures enabling to continuing operation beyond 100,000 EOH. This paper presents strategic options for hot-gas-path component life entension.
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Muthu, S. Esakki, A. Selwyn, Hardik Roy, and Girish K. Degaonkar. "Life Extension of Axial Compressor Disc of a Turbo-Shaft Engine." In ASME 2013 Gas Turbine India Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gtindia2013-3645.
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The cost of aero engine and its maintenance is going higher day by day, the life of the critical parts and its availability play a major role to keep the fleet in operation. Engine components works under extremely high stress levels so the life of the components is limited. Most of the critical components are retired by the operator before they reach their theoretical life. The uncertainty in accurate life prediction induces the risk which is the cause for premature retirement. Metallurgical study of the life expired components and fatigue/fracture methodologies are used to estimate the residual useful life of the components. This paper describes the life extension methodology used for an axial compressor disc of turbo-shaft engine. The disc has completed its safe life in the aircraft. The studies are carried out to determine the residual life of the disc to extend the life. Two life completed disc are identified. Specimens are cut from the disc for tensile test and LCF tests. Probable mission cycles for the aircraft are collected and fatigue cycle data are prepared. Finite element based stress analysis is carried out using Ansys software with multi axial loads. Based on the stress analysis, disc bore and pin hole are identified as critical area. The computed stress–strain response is used to predict the fatigue crack initiation life using effective strain range parameters on the critical areas. Fatigue damage for different mission cycles are also calculated using critical plane approach. The plane where crack initiate is called critical plane and it is calculated iteratively based on the nodal stress result. Life for different mission cycle is calculated and minimum life of all the cycle is determined. This calculated life gives the amount of residual life available and the scope for life extension. The disc is tested in cyclic spin test rig to confirm the remaining potential life. The test results are compared with the numerical estimation. It is found that the residual life of the life completed component has got potential life of one more overhaul.
Reports on the topic "Component life extension"
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McEntee, Alice, Sonia Hines, Joshua Trigg, Kate Fairweather, Ashleigh Guillaumier, Jane Fischer, Billie Bonevski, James A. Smith, Carlene Wilson, and Jacqueline Bowden. Tobacco cessation in CALD communities. The Sax Institute, June 2022. http://dx.doi.org/10.57022/sneg4189.
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Background Australia is a multi-cultural society with increasing rates of people from culturally and linguistically diverse (CALD) backgrounds. On average, CALD groups have higher rates of tobacco use, lower participation in cancer screening programs, and poorer health outcomes than the general Australian population. Lower cancer screening and smoking cessation rates are due to differing cultural norms, health-related attitudes, and beliefs, and language barriers. Interventions can help address these potential barriers and increase tobacco cessation and cancer screening rates among CALD groups. Cancer Council NSW (CCNSW) aims to reduce the impact of cancer and improve cancer outcomes for priority populations including CALD communities. In line with this objective, CCNSW commissioned this rapid review of interventions implemented in Australia and comparable countries. Review questions This review aimed to address the following specific questions: Question 1 (Q1): What smoking cessation interventions have been proven effective in reducing or preventing smoking among culturally and linguistically diverse communities? Question 2 (Q2): What screening interventions have proven effective in increasing participation in population cancer screening programs among culturally and linguistically diverse populations? This review focused on Chinese-, Vietnamese- and Arabic-speaking people as they are the largest CALD groups in Australia and have high rates of tobacco use and poor screening adherence in NSW. Summary of methods An extensive search of peer-reviewed and grey literature published between January 2013-March 2022 identified 19 eligible studies for inclusion in the Q1 review and 49 studies for the Q2 review. The National Health and Medical Research Council (NHMRC) Levels of Evidence and Joanna Briggs Institute’s (JBI) Critical Appraisal Tools were used to assess the robustness and quality of the included studies, respectively. Key findings Findings are reported by components of an intervention overall and for each CALD group. By understanding the effectiveness of individual components, results will demonstrate key building blocks of an effective intervention. Question 1: What smoking cessation interventions have been proven effective in reducing or preventing smoking among culturally and linguistically diverse communities? Thirteen of the 19 studies were Level IV (L4) evidence, four were Level III (L3), one was Level II (L2), none were L1 (highest level of evidence) and one study’s evidence level was unable to be determined. The quality of included studies varied. Fifteen tobacco cessation intervention components were included, with most interventions involving at least three components (range 2-6). Written information (14 studies), and education sessions (10 studies) were the most common components included in an intervention. Eight of the 15 intervention components explored had promising evidence for use with Chinese-speaking participants (written information, education sessions, visual information, counselling, involving a family member or friend, nicotine replacement therapy, branded merchandise, and mobile messaging). Another two components (media campaign and telephone follow-up) had evidence aggregated across CALD groups (i.e., results for Chinese-speaking participants were combined with other CALD group(s)). No intervention component was deemed of sufficient evidence for use with Vietnamese-speaking participants and four intervention components had aggregated evidence (written information, education sessions, counselling, nicotine replacement therapy). Counselling was the only intervention component to have promising evidence for use with Arabic-speaking participants and one had mixed evidence (written information). Question 2: What screening interventions have proven effective in increasing participation in population cancer screening programs among culturally and linguistically diverse populations? Two of the 49 studies were Level I (L1) evidence, 13 L2, seven L3, 25 L4 and two studies’ level of evidence was unable to be determined. Eighteen intervention components were assessed with most interventions involving 3-4 components (range 1-6). Education sessions (32 studies), written information (23 studies) and patient navigation (10 studies) were the most common components. Seven of the 18 cancer screening intervention components had promising evidence to support their use with Vietnamese-speaking participants (education sessions, written information, patient navigation, visual information, peer/community health worker, counselling, and peer experience). The component, opportunity to be screened (e.g. mailed or handed a bowel screening test), had aggregated evidence regarding its use with Vietnamese-speaking participants. Seven intervention components (education session, written information, visual information, peer/community health worker, opportunity to be screened, counselling, and branded merchandise) also had promising evidence to support their use with Chinese-speaking participants whilst two components had mixed (patient navigation) or aggregated (media campaign) evidence. One intervention component for use with Arabic-speaking participants had promising evidence to support its use (opportunity to be screened) and eight intervention components had mixed or aggregated support (education sessions, written information, patient navigation, visual information, peer/community health worker, peer experience, media campaign, and anatomical models). Gaps in the evidence There were four noteworthy gaps in the evidence: 1. No systematic review was captured for Q1, and only two studies were randomised controlled trials. Much of the evidence is therefore based on lower level study designs, with risk of bias. 2. Many studies provided inadequate detail regarding their intervention design which impacts both the quality appraisal and how mixed finding results can be interpreted. 3. Several intervention components were found to have supportive evidence available only at the aggregate level. Further research is warranted to determine the interventions effectiveness with the individual CALD participant group only. 4. The evidence regarding the effectiveness of certain intervention components were either unknown (no studies) or insufficient (only one study) across CALD groups. This was the predominately the case for Arabic-speaking participants for both Q1 and Q2, and for Vietnamese-speaking participants for Q1. Further research is therefore warranted. Applicability Most of the intervention components included in this review are applicable for use in the Australian context, and NSW specifically. However, intervention components assessed as having insufficient, mixed, or no evidence require further research. Cancer screening and tobacco cessation interventions targeting Chinese-speaking participants were more common and therefore showed more evidence of effectiveness for the intervention components explored. There was support for cancer screening intervention components targeting Vietnamese-speaking participants but not for tobacco cessation interventions. There were few interventions implemented for Arabic-speaking participants that addressed tobacco cessation and screening adherence. Much of the evidence for Vietnamese and Arabic-speaking participants was further limited by studies co-recruiting multiple CALD groups and reporting aggregate results. Conclusion There is sound evidence for use of a range of intervention components to address tobacco cessation and cancer screening adherence among Chinese-speaking populations, and cancer screening adherence among Vietnamese-speaking populations. Evidence is lacking regarding the effectiveness of tobacco cessation interventions with Vietnamese- and Arabic-speaking participants, and cancer screening interventions for Arabic-speaking participants. More research is required to determine whether components considered effective for use in one CALD group are applicable to other CALD populations.
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Hovav, Ran, Peggy Ozias-Akins, and Scott A. Jackson. The genetics of pod-filling in peanut under water-limiting conditions. United States Department of Agriculture, January 2012. http://dx.doi.org/10.32747/2012.7597923.bard.
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Pod-filling, an important yield-determining stage is strongly influenced by water stress. This is particularly true for peanut (Arachishypogaea), wherein pods are developed underground and are directly affected by the water condition. Pod-filling in peanut has a significant genetic component as well, since genotypes are considerably varied in their pod-fill (PF) and seed-fill (SF) potential. The goals of this research were to: Examine the effects of genotype, irrigation, and genotype X irrigation on PF and SF. Detect global changes in mRNA and metabolites levels that accompany PF and SF. Explore the response of the duplicate peanut pod transcriptome to drought stress. Study how entire duplicated PF regulatory processes are networked within a polyploid organism. Discover locus-specific SNP markers and map pod quality traits under different environments. The research included genotypes and segregating populations from Israel and US that are varied in PF, SF and their tolerance to water deficit. Initially, an extensive field trial was conducted to investigate the effects of genotype, irrigation, and genotype X irrigation on PF and SF. Significant irrigation and genotypic effect was observed for the two main PF related traits, "seed ratio" and "dead-end ratio", demonstrating that reduction in irrigation directly influences the developing pods as a result of low water potential. Although the Irrigation × Genotype interaction was not statistically significant, one genotype (line 53) was found to be more sensitive to low irrigation treatments. Two RNAseq studies were simultaneously conducted in IL and the USA to characterize expression changes that accompany shell ("source") and seed ("sink") biogenesis in peanut. Both studies showed that SF and PF processes are very dynamic and undergo very rapid change in the accumulation of RNA, nutrients, and oil. Some genotypes differ in transcript accumulation rates, which can explain their difference in SF and PF potential; like cvHanoch that was found to be more enriched than line 53 in processes involving the generation of metabolites and energy at the beginning of seed development. Interestingly, an opposite situation was found in pericarp development, wherein rapid cell wall maturation processes were up-regulated in line 53. Although no significant effect was found for the irrigation level on seed transcriptome in general, and particularly on subgenomic assignment (that was found almost comparable to a 1:1 for A- and B- subgenomes), more specific homoeologous expression changes associated with particular biosynthesis pathways were found. For example, some significant A- and B- biases were observed in particular parts of the oil related gene expression network and several candidate genes with potential influence on oil content and SF were further examined. Substation achievement of the current program was the development and application of new SNP detection and mapping methods for peanut. Two major efforts on this direction were performed. In IL, a GBS approach was developed to map pod quality traits on Hanoch X 53 F2/F3 generations. Although the GBS approach was found to be less effective for our genetic system, it still succeeded to find significant mapping locations for several traits like testa color (linkage A10), number of seeds/pods (A5) and pod wart resistance (B7). In the USA, a SNP array was developed and applied for peanut, which is based on whole genome re-sequencing of 20 genotypes. This chip was used to map pod quality related traits in a Tifrunner x NC3033 RIL population. It was phenotyped for three years, including a new x-ray method to phenotype seed-fill and seed density. The total map size was 1229.7 cM with 1320 markers assigned. Based on this linkage map, 21 QTLs were identified for the traits 16/64 weight, kernel percentage, seed and pod weight, double pod and pod area. Collectively, this research serves as the first fundamental effort in peanut for understanding the PF and SF components, as a whole, and as influenced by the irrigation level. Results of the proposed study will also generate information and materials that will benefit peanut breeding by facilitating selection for reduced linkage drag during introgression of disease resistance traits into elite cultivars. BARD Report - Project4540 Page 2 of 10
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Naim, Michael, Andrew Spielman, Shlomo Nir, and Ann Noble. Bitter Taste Transduction: Cellular Pathways, Inhibition and Implications for Human Acceptance of Agricultural Food Products. United States Department of Agriculture, February 2000. http://dx.doi.org/10.32747/2000.7695839.bard.
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Historically, the aversive response of humans and other mammals to bitter-taste substances has been useful for survival, since many toxic constituents taste bitter. Today, the range of foods available is more diverse. Many bitter foods are not only safe for consumption but contain bitter constituents that provide nutritional benefits. Despite this, these foods are often eliminated from our current diets because of their unacceptable bitterness. Extensive technology has been developed to remove or mask bitterness in foods, but a lack of understanding of the mechanisms of bitterness perception at the taste receptor level has prevented the development of inhibitors or efficient methods for reducing bitterness. In our original application we proposed to: (a) investigate the time course and effect of selected bitter tastants relevant to agricultural products on the formation of intracellular signal molecules (cAMP, IP3, Ca2+) in intact taste cells, in model cells and in membranes derived therefrom; (b) study the effect of specific bitter taste inhibitors on messenger formation and identify G-proteins that may be involved in tastant-induced bitter sensation; (c) investigate interactions and self-aggregation of bitter tastants within membranes; (d) study human sensory responses over time to these bitter-taste stimuli and inhibitors in order to validate the biochemical data. Quench-flow module (QFM) and fast pipetting system (FPS) allowed us to monitor fast release of the aforementioned signal molecules (cGMP, as a putative initial signal was substituted for Ca2+ ions) - using taste membranes and intact taste cells in a time range below 500 ms (real time of taste sensation) - in response to bitter-taste stimulation. Limonin (citrus) and catechin (wine) were found to reduce cellular cAMP and increase IP3 contents. Naringin (citrus) stimulated an IP3 increase whereas the cheese-derived bitter peptide cyclo(leu-Trp) reduced IP3 but significantly increased cAMP levels. Thus, specific transduction pathways were identified, the results support the notion of multiple transduction pathways for bitter taste and cross-talk between a few of those transduction pathways. Furthermore, amphipathic tastants permeate rapidly (within seconds) into liposomes and taste cells suggesting their availability for direct activation of signal transduction components by means of receptor-independent mechanisms within the time course of taste sensation. The activation of pigment movement and transduction pathways in frog melanophores by these tastants supports such mechanisms. Some bitter tastants, due to their amphipathic properties, permeated (or interacted with) into a bitter tastant inhibitor (specific phospholipid mixture) which apparently forms micelles. Thus, a mechanism via which this bitter taste inhibitor acts is proposed. Human sensory evaluation experiments humans performed according to their 6-n-propyl thiouracil (PROP) status (non-tasters, tasters, super-tasters), indicated differential perception of bitterness threshold and intensity of these bitter compounds by different individuals independent of PROP status. This suggests that natural products containing bitter compounds (e.g., naringin and limonin in citrus), are perceived very differently, and are in line with multiple transduction pathways suggested in the biochemical experiments. This project provides the first comprehensive effort to explore the molecular basis of bitter taste at the taste-cell level induced by economically important and agriculturally relevant food products. The findings, proposing a mechanism for bitter-taste inhibition by a bitter taste inhibitor (made up of food components) pave the way for the development of new, and perhaps more potent bitter-taste inhibitors which may eventually become economically relevant.
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Rankin, Nicole, Deborah McGregor, Candice Donnelly, Bethany Van Dort, Richard De Abreu Lourenco, Anne Cust, and Emily Stone. Lung cancer screening using low-dose computed tomography for high risk populations: Investigating effectiveness and screening program implementation considerations: An Evidence Check rapid review brokered by the Sax Institute (www.saxinstitute.org.au) for the Cancer Institute NSW. The Sax Institute, October 2019. http://dx.doi.org/10.57022/clzt5093.
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Background Lung cancer is the number one cause of cancer death worldwide.(1) It is the fifth most commonly diagnosed cancer in Australia (12,741 cases diagnosed in 2018) and the leading cause of cancer death.(2) The number of years of potential life lost to lung cancer in Australia is estimated to be 58,450, similar to that of colorectal and breast cancer combined.(3) While tobacco control strategies are most effective for disease prevention in the general population, early detection via low dose computed tomography (LDCT) screening in high-risk populations is a viable option for detecting asymptomatic disease in current (13%) and former (24%) Australian smokers.(4) The purpose of this Evidence Check review is to identify and analyse existing and emerging evidence for LDCT lung cancer screening in high-risk individuals to guide future program and policy planning. Evidence Check questions This review aimed to address the following questions: 1. What is the evidence for the effectiveness of lung cancer screening for higher-risk individuals? 2. What is the evidence of potential harms from lung cancer screening for higher-risk individuals? 3. What are the main components of recent major lung cancer screening programs or trials? 4. What is the cost-effectiveness of lung cancer screening programs (include studies of cost–utility)? Summary of methods The authors searched the peer-reviewed literature across three databases (MEDLINE, PsycINFO and Embase) for existing systematic reviews and original studies published between 1 January 2009 and 8 August 2019. Fifteen systematic reviews (of which 8 were contemporary) and 64 original publications met the inclusion criteria set across the four questions. Key findings Question 1: What is the evidence for the effectiveness of lung cancer screening for higher-risk individuals? There is sufficient evidence from systematic reviews and meta-analyses of combined (pooled) data from screening trials (of high-risk individuals) to indicate that LDCT examination is clinically effective in reducing lung cancer mortality. In 2011, the landmark National Lung Cancer Screening Trial (NLST, a large-scale randomised controlled trial [RCT] conducted in the US) reported a 20% (95% CI 6.8% – 26.7%; P=0.004) relative reduction in mortality among long-term heavy smokers over three rounds of annual screening. High-risk eligibility criteria was defined as people aged 55–74 years with a smoking history of ≥30 pack-years (years in which a smoker has consumed 20-plus cigarettes each day) and, for former smokers, ≥30 pack-years and have quit within the past 15 years.(5) All-cause mortality was reduced by 6.7% (95% CI, 1.2% – 13.6%; P=0.02). Initial data from the second landmark RCT, the NEderlands-Leuvens Longkanker Screenings ONderzoek (known as the NELSON trial), have found an even greater reduction of 26% (95% CI, 9% – 41%) in lung cancer mortality, with full trial results yet to be published.(6, 7) Pooled analyses, including several smaller-scale European LDCT screening trials insufficiently powered in their own right, collectively demonstrate a statistically significant reduction in lung cancer mortality (RR 0.82, 95% CI 0.73–0.91).(8) Despite the reduction in all-cause mortality found in the NLST, pooled analyses of seven trials found no statistically significant difference in all-cause mortality (RR 0.95, 95% CI 0.90–1.00).(8) However, cancer-specific mortality is currently the most relevant outcome in cancer screening trials. These seven trials demonstrated a significantly greater proportion of early stage cancers in LDCT groups compared with controls (RR 2.08, 95% CI 1.43–3.03). Thus, when considering results across mortality outcomes and early stage cancers diagnosed, LDCT screening is considered to be clinically effective. Question 2: What is the evidence of potential harms from lung cancer screening for higher-risk individuals? The harms of LDCT lung cancer screening include false positive tests and the consequences of unnecessary invasive follow-up procedures for conditions that are eventually diagnosed as benign. While LDCT screening leads to an increased frequency of invasive procedures, it does not result in greater mortality soon after an invasive procedure (in trial settings when compared with the control arm).(8) Overdiagnosis, exposure to radiation, psychological distress and an impact on quality of life are other known harms. Systematic review evidence indicates the benefits of LDCT screening are likely to outweigh the harms. The potential harms are likely to be reduced as refinements are made to LDCT screening protocols through: i) the application of risk predication models (e.g. the PLCOm2012), which enable a more accurate selection of the high-risk population through the use of specific criteria (beyond age and smoking history); ii) the use of nodule management algorithms (e.g. Lung-RADS, PanCan), which assist in the diagnostic evaluation of screen-detected nodules and cancers (e.g. more precise volumetric assessment of nodules); and, iii) more judicious selection of patients for invasive procedures. Recent evidence suggests a positive LDCT result may transiently increase psychological distress but does not have long-term adverse effects on psychological distress or health-related quality of life (HRQoL). With regards to smoking cessation, there is no evidence to suggest screening participation invokes a false sense of assurance in smokers, nor a reduction in motivation to quit. The NELSON and Danish trials found no difference in smoking cessation rates between LDCT screening and control groups. Higher net cessation rates, compared with general population, suggest those who participate in screening trials may already be motivated to quit. Question 3: What are the main components of recent major lung cancer screening programs or trials? There are no systematic reviews that capture the main components of recent major lung cancer screening trials and programs. We extracted evidence from original studies and clinical guidance documents and organised this into key groups to form a concise set of components for potential implementation of a national lung cancer screening program in Australia: 1. Identifying the high-risk population: recruitment, eligibility, selection and referral 2. Educating the public, people at high risk and healthcare providers; this includes creating awareness of lung cancer, the benefits and harms of LDCT screening, and shared decision-making 3. Components necessary for health services to deliver a screening program: a. Planning phase: e.g. human resources to coordinate the program, electronic data systems that integrate medical records information and link to an established national registry b. Implementation phase: e.g. human and technological resources required to conduct LDCT examinations, interpretation of reports and communication of results to participants c. Monitoring and evaluation phase: e.g. monitoring outcomes across patients, radiological reporting, compliance with established standards and a quality assurance program 4. Data reporting and research, e.g. audit and feedback to multidisciplinary teams, reporting outcomes to enhance international research into LDCT screening 5. Incorporation of smoking cessation interventions, e.g. specific programs designed for LDCT screening or referral to existing community or hospital-based services that deliver cessation interventions. Most original studies are single-institution evaluations that contain descriptive data about the processes required to establish and implement a high-risk population-based screening program. Across all studies there is a consistent message as to the challenges and complexities of establishing LDCT screening programs to attract people at high risk who will receive the greatest benefits from participation. With regards to smoking cessation, evidence from one systematic review indicates the optimal strategy for incorporating smoking cessation interventions into a LDCT screening program is unclear. There is widespread agreement that LDCT screening attendance presents a ‘teachable moment’ for cessation advice, especially among those people who receive a positive scan result. Smoking cessation is an area of significant research investment; for instance, eight US-based clinical trials are now underway that aim to address how best to design and deliver cessation programs within large-scale LDCT screening programs.(9) Question 4: What is the cost-effectiveness of lung cancer screening programs (include studies of cost–utility)? Assessing the value or cost-effectiveness of LDCT screening involves a complex interplay of factors including data on effectiveness and costs, and institutional context. A key input is data about the effectiveness of potential and current screening programs with respect to case detection, and the likely outcomes of treating those cases sooner (in the presence of LDCT screening) as opposed to later (in the absence of LDCT screening). Evidence about the cost-effectiveness of LDCT screening programs has been summarised in two systematic reviews. We identified a further 13 studies—five modelling studies, one discrete choice experiment and seven articles—that used a variety of methods to assess cost-effectiveness. Three modelling studies indicated LDCT screening was cost-effective in the settings of the US and Europe. Two studies—one from Australia and one from New Zealand—reported LDCT screening would not be cost-effective using NLST-like protocols. We anticipate that, following the full publication of the NELSON trial, cost-effectiveness studies will likely be updated with new data that reduce uncertainty about factors that influence modelling outcomes, including the findings of indeterminate nodules. Gaps in the evidence There is a large and accessible body of evidence as to the effectiveness (Q1) and harms (Q2) of LDCT screening for lung cancer. Nevertheless, there are significant gaps in the evidence about the program components that are required to implement an effective LDCT screening program (Q3). Questions about LDCT screening acceptability and feasibility were not explicitly included in the scope. However, as the evidence is based primarily on US programs and UK pilot studies, the relevance to the local setting requires careful consideration. The Queensland Lung Cancer Screening Study provides feasibility data about clinical aspects of LDCT screening but little about program design. The International Lung Screening Trial is still in the recruitment phase and findings are not yet available for inclusion in this Evidence Check. The Australian Population Based Screening Framework was developed to “inform decision-makers on the key issues to be considered when assessing potential screening programs in Australia”.(10) As the Framework is specific to population-based, rather than high-risk, screening programs, there is a lack of clarity about transferability of criteria. However, the Framework criteria do stipulate that a screening program must be acceptable to “important subgroups such as target participants who are from culturally and linguistically diverse backgrounds, Aboriginal and Torres Strait Islander people, people from disadvantaged groups and people with a disability”.(10) An extensive search of the literature highlighted that there is very little information about the acceptability of LDCT screening to these population groups in Australia. Yet they are part of the high-risk population.(10) There are also considerable gaps in the evidence about the cost-effectiveness of LDCT screening in different settings, including Australia. The evidence base in this area is rapidly evolving and is likely to include new data from the NELSON trial and incorporate data about the costs of targeted- and immuno-therapies as these treatments become more widely available in Australia.
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Carpita, Nicholas C., Ruth Ben-Arie, and Amnon Lers. Pectin Cross-Linking Dynamics and Wall Softening during Fruit Ripening. United States Department of Agriculture, July 2002. http://dx.doi.org/10.32747/2002.7585197.bard.
Full textAbstract:
Our study was designed to elucidate the chemical determinants of pectin cross-linking in developing fruits of apple and peach and to evaluate the role of breakage cross-linkages in swelling, softening, and cell separation during the ripening. Peaches cell walls soften and swell considerably during the ripening, whereas apples fruit cells maintain wall firmness but cells separate during late stages of ripening. We used a "double-reduction" technique to show that levels of non-methyl esters of polyuronic acid molecules were constant during the development and ripening and decreased only in overripe fruit. In peach, methyl and non-methyl esters increased during the development and decreased markedly during the ripening. Non-methyl ester linkages in both fruit decreased accompanied fruit softening. The identity of the second component of the linkage and its definitive role in the fruit softening remain elusive. In preliminary examination of isolated apples cell walls, we found that phenolic compounds accumulate early in wall development but decrease markedly during ripening. Quantitative texture analysis was used to correlate with changes to wall chemistry from the fresh-picked ripe stage to the stage during storage when the cell separation occurs. Cell wall composition is similar in all cultivars, with arabinose as the principal neutral sugar. Extensive de-branching of these highly branched arabinans pre-stages softening and cell-cell separation during over-ripening of apple. The longer 5-arabinans remain attached to the major pectic polymer rhamnogalacturonan I (RG I) backbone. The degree of RG I branching, as judged from the ratios of 2-Rha:2,4-Rha, also decreases, specially after an extensive arabinan de-branching. Loss of the 4-Rham linkages correlated strongly with the softening of the fruit. Loss of the monomer or polymer linked to the RG I produce directly or indirectly the softening of the fruit. This result will help to understand the fruit softening and to have better control of the textural changes in fruit during the ripening and especially during the storage. 'Wooliness', an undesirable mealy texture that is induced during chilling of some peach cultivars, greatly reduces the fruit storage possibilities. In order to examine the hypothesis that the basis for this disorder is related to abnormality in the cell wall softening process we have carried out a comparative analysis using the resistant cultivar, Sunsnow, and a sensitive one, Hermosa. We investigated the activity of several pectin- and glycan-modifying enzymes and the expression of their genes during ripening, chilling, and subsequent shelf-life. The changes in carbohydrate status and in methyl vs. non-methyl uronate ester levels in the walls of these cultivars were examined as well to provide a basis for comparison of the relevant gene expression that may impact appearance of the wooly character. The activities of the specific polygalacturonase (PGase) and a CMC-cellulase activities are significantly elevated in walls of peaches that have become wooly. Cellulase activities correlated well with increased level of the transcript, but differential expression of PGase did not correspond with the observed pattern of mRNA accumulation. When expression of ethylene biosynthesis related genes was followed no significant differences in ACC synthase gene expression was observed in the wooly fruit while the normal activation of the ACC oxidase was partially repressed in the Hermosa wooly fruits. Normal ripening-related loss of the uronic acid-rich polymers was stalled in the wooly Hermosa inconsistent with the observed elevation in a specific PGase activity but consistent with PG gene expression. In general, analysis of the level of total esterification, degree of methyl esterification and level of non-methyl esters did not reveal any major alterations between the different fruit varieties or between normal and abnormal ripening. Some decrease in the level of uronic acids methyl esterification was observed for both Hermosa and Sunsnow undergoing ripening following storage at low temperature but not in fruits ripening after harvest. Our results support a role for imbalanced cell wall degradation as a basis for the chilling disorder. While these results do not support a role for the imbalance between PG and pectin methyl esterase (PME) activities as the basis for the disorder they suggest a possible role for imbalance between cellulose and other cell wall polymer degradation during the softening process.
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Börjesson, Patrik, Maria Eggertsen, Lachlan Fetterplace, Ann-Britt Florin, Ronny Fredriksson, Susanna Fredriksson, Patrik Kraufvelin, et al. Long-term effects of no-take zones in Swedish waters. Edited by Ulf Bergström, Charlotte Berkström, and Mattias Sköld. Department of Aquatic Resources, Swedish University of Agricultural Sciences, 2023. http://dx.doi.org/10.54612/a.10da2mgf51.
Full textAbstract:
Marine protected areas (MPAs) are increasingly established worldwide to protect and restore degraded ecosystems. However, the level of protection varies among MPAs and has been found to affect the outcome of the closure. In no-take zones (NTZs), no fishing or extraction of marine organisms is allowed. The EU Commission recently committed to protect 30% of European waters by 2030 through the updated Biodiversity Strategy. Importantly, one third of these 30% should be of strict protection. Exactly what is meant by strict protection is not entirely clear, but fishing would likely have to be fully or largely prohibited in these areas. This new target for strictly protected areas highlights the need to evaluate the ecological effects of NTZs, particularly in regions like northern Europe where such evaluations are scarce. The Swedish NTZs made up approximately two thirds of the total areal extent of NTZs in Europe a decade ago. Given that these areas have been closed for at least 10 years and can provide insights into long-term effects of NTZs on fish and ecosystems, they are of broad interest in light of the new 10% strict protection by 2030 commitment by EU member states. In total, eight NTZs in Swedish coastal and offshore waters were evaluated in the current report, with respect to primarily the responses of focal species for the conservation measure, but in some of the areas also ecosystem responses. Five of the NTZs were established in 2009-2011, as part of a government commission, while the other three had been established earlier. The results of the evaluations are presented in a synthesis and also in separate, more detailed chapters for each of the eight NTZs. Overall, the results suggest that NTZs can increase abundances and biomasses of fish and decapod crustaceans, given that the closed areas are strategically placed and of an appropriate size in relation to the life cycle of the focal species. A meta-regression of the effects on focal species of the NTZs showed that CPUE was on average 2.6 times higher after three years of protection, and 3.8 times higher than in the fished reference areas after six years of protection. The proportion of old and large individuals increased in most NTZs, and thereby also the reproductive potential of populations. The increase in abundance of large predatory fish also likely contributed to restoring ecosystem functions, such as top-down control. These effects appeared after a 5-year period and in many cases remained and continued to increase in the longer term (>10 years). In the two areas where cod was the focal species of the NTZs, positive responses were weak, likely as an effect of long-term past, and in the Kattegat still present, recruitment overfishing. In the Baltic Sea, predation by grey seal and cormorant was in some cases so high that it likely counteracted the positive effects of removing fisheries and led to stock declines in the NTZs. In most cases, the introduction of the NTZs has likely decreased the total fishing effort rather than displacing it to adjacent areas. In the Kattegat NTZ, however, the purpose was explicitly to displace an unselective coastal mixed bottom-trawl fishery targeting Norway lobster and flatfish to areas where the bycatches of mature cod were smaller. In two areas that were reopened to fishing after 5 years, the positive effects of the NTZs on fish stocks eroded quickly to pre-closure levels despite that the areas remained closed during the spawning period, highlighting that permanent closures may be necessary to maintain positive effects. We conclude from the Swedish case studies that NTZs may well function as a complement to other fisheries management measures, such as catch, effort and gear regulations. The experiences from the current evaluation show that NTZs can be an important tool for fisheries management especially for local coastal fish populations and areas with mixed fisheries, as well as in cases where there is a need to counteract adverse ecosystem effects of fishing. NTZs are also needed as reference for marine environmental management, and for understanding the effects of fishing on fish populations and other ecosystem components in relation to other pressures. MPAs where the protection of both fish and their habitats is combined may be an important instrument for ecosystembased management, where the recovery of large predatory fish may lead to a restoration of important ecosystem functions and contribute to improving decayed habitats. With the new Biodiversity Strategy, EUs level of ambition for marine conservation increases significantly, with the goal of 30% of coastal and marine waters protected by 2030, and, importantly, one third of these areas being strictly protected. From a conservation perspective, rare, sensitive and/or charismatic species or habitats are often in focus when designating MPAs, and displacement of fisheries is then considered an unwanted side effect. However, if the establishment of strictly protected areas also aims to rebuild fish stocks, these MPAs should be placed in heavily fished areas and designed to protect depleted populations by accounting for their home ranges to generate positive outcomes. Thus, extensive displacement of fisheries is required to reach benefits for depleted populations, and need to be accounted for e.g. by specific regulations outside the strictly protected areas. These new extensive EU goals for MPA establishment pose a challenge for management, but at the same time offer an opportunity to bridge the current gap between conservation and fisheries management.
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Aharoni, Asaph, Zhangjun Fei, Efraim Lewinsohn, Arthur Schaffer, and Yaakov Tadmor. System Approach to Understanding the Metabolic Diversity in Melon. United States Department of Agriculture, July 2013. http://dx.doi.org/10.32747/2013.7593400.bard.
Full textAbstract:
Fruit quality is determined by numerous genetic factors that affect taste, aroma, color, texture, nutritional value and shelf life. To unravel the genetic components involved in the metabolic pathways behind these traits, the major goal of the project was to identify novel genes that are involved in, or that regulate, these pathways using correlation analysis between genotype, metabolite and gene expression data. The original and specific research objectives were: (1) Collection of replicated fruit from a population of 96 RI lines derived from parents distinguished by great diversity in fruit development and quality phenotypes, (2) Phenotypic and metabolic profiling of mature fruit from all 96 RI lines and their parents, (3) 454 pyrosequencing of cDNA representing mRNA of mature fruit from each line to facilitate gene expression analysis based on relative EST abundance, (4) Development of a database modeled after an existing database developed for tomato introgression lines (ILs) to facilitate online data analysis by members of this project and by researchers around the world. The main functions of the database will be to store and present metabolite and gene expression data so that correlations can be drawn between variation in target traits or metabolites across the RI population members and variation in gene expression to identify candidate genes which may impact phenotypic and chemical traits of interest, (5) Selection of RI lines for segregation and/or hybridization (crosses) analysis to ascertain whether or not genes associated with traits through gene expression/metabolite correlation analysis are indeed contributors to said traits. The overall research strategy was to utilize an available recombinant inbred population of melon (Cucumis melo L.) derived from phenotypically diverse parents and for which over 800 molecular markers have been mapped for the association of metabolic trait and gene expression QTLs. Transcriptomic data were obtained by high throughput sequencing using the Illumina platform instead of the originally planned 454 platform. The change was due to the fast advancement and proven advantages of the Illumina platform, as explained in the first annual scientific report. Metabolic data were collected using both targeted (sugars, organic acids, carotenoids) and non-targeted metabolomics analysis methodologies. Genes whose expression patterns were associated with variation of particular metabolites or fruit quality traits represent candidates for the molecular mechanisms that underlie them. Candidate genes that may encode enzymes catalyzingbiosynthetic steps in the production of volatile compounds of interest, downstream catabolic processes of aromatic amino acids and regulatory genes were selected and are in the process of functional analyses. Several of these are genes represent unanticipated effectors of compound accumulation that could not be identified using traditional approaches. According to the original plan, the Cucurbit Genomics Network (http://www.icugi.org/), developed through an earlier BARD project (IS-3333-02), was expanded to serve as a public portal for the extensive metabolomics and transcriptomic data resulting from the current project. Importantly, this database was also expanded to include genomic and metabolomic resources of all the cucurbit crops, including genomes of cucumber and watermelon, EST collections, genetic maps, metabolite data and additional information. In addition, the database provides tools enabling researchers to identify genes, the expression patterns of which correlate with traits of interest. The project has significantly expanded the existing EST resource for melon and provides new molecular tools for marker-assisted selection. This information will be opened to the public by the end of 2013, upon the first publication describing the transcriptomic and metabolomics resources developed through the project. In addition, well-characterized RI lines are available to enable targeted breeding for genes of interest. Segregation of the RI lines for specific metabolites of interest has been shown, demonstrating the utility in these lines and our new molecular and metabolic data as a basis for selection targeting specific flavor, quality, nutritional and/or defensive compounds. To summarize, all the specific goals of the project have been achieved and in many cases exceeded. Large scale trascriptomic and metabolomic resources have been developed for melon and will soon become available to the community. The usefulness of these has been validated. A number of novel genes involved in fruit ripening have been selected and are currently being functionally analyzed. We thus fully addressed our obligations to the project. In our view, however, the potential value of the project outcomes as ultimately manifested may be far greater than originally anticipated. The resources developed and expanded under this project, and the tools created for using them will enable us, and others, to continue to employ resulting data and discoveries in future studies with benefits both in basic and applied agricultural - scientific research.