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Sample records for repair engines mechanical

  1. A qualitative engineering analysis of occlusion effects on mandibular fracture repair mechanics.

    Science.gov (United States)

    Katona, Thomas R

    2011-01-01

    Objectives. The purpose of this analytical study was to examine and critique the engineering foundations of commonly accepted biomechanical principles of mandible fracture repair. Materials and Methods. Basic principles of static equilibrium were applied to intact and plated mandibles, but instead of the traditional lever forces, the mandibles were subjected to more realistic occlusal forces. Results. These loading conditions produced stress distributions within the intact mandible that were very different and more complex than the customary lever-based gradient. The analyses also demonstrated the entirely different mechanical environments within intact and plated mandibles. Conclusions. Because the loading and geometry of the lever-idealized mandible is incomplete, the associated widely accepted bone stress distribution (tension on top and compression on the bottom) should not be assumed. Furthermore, the stress gradients within the bone of an intact mandible should not be extrapolated to the mechanical environment within the plated regions of a fractured mandible.

  2. Mechanical engineering

    CERN Document Server

    Darbyshire, Alan

    2010-01-01

    Alan Darbyshire's best-selling text book provides five-star high quality content to a potential audience of 13,000 engineering students. It explains the most popular specialist units of the Mechanical Engineering, Manufacturing Engineering and Operations & Maintenance Engineering pathways of the new 2010 BTEC National Engineering syllabus. This challenging textbook also features contributions from specialist lecturers, ensuring that no stone is left unturned.

  3. Engineering mechanics

    CERN Document Server

    Gross, Dietmar; Schröder, Jörg; Wall, Wolfgang A; Rajapakse, Nimal

    Statics is the first volume of a three-volume textbook on Engineering Mechanics. The authors, using a time-honoured straightforward and flexible approach, present the basic concepts and principles of mechanics in the clearest and simplest form possible to advanced undergraduate engineering students of various disciplines and different educational backgrounds. An important objective of this book is to develop problem solving skills in a systematic manner. Another aim of this volume is to provide engineering students as well as practising engineers with a solid foundation to help them bridge the gap between undergraduate studies on the one hand and advanced courses on mechanics and/or practical engineering problems on the other. The book contains numerous examples, along with their complete solutions. Emphasis is placed upon student participation in problem solving. The contents of the book correspond to the topics normally covered in courses on basic engineering mechanics at universities and colleges. Now in i...

  4. Strategies for cell engineering in tissue repair.

    Science.gov (United States)

    Brown, R A; Smith, K D; Angus McGrouther, D

    1997-01-01

    Cellular and tissue engineering are new areas of research, currently attracting considerable interest because of the remarkable potential they have for clinical application. Some claims have indeed been dramatic, including the possibility of growing complete, artificial organs, such as the liver. However, amid such long-term aspirations there is the very real possibility that small tissues (artificial grafts) may be fabricated in the near future for use in reconstructive surgery. Logically, we should focus on how it is possible to produce modest, engineered tissues for tissue repair. It is evident that strategies to date either depend on innate information within implanted cells, to reform the target tissue or aim to provide appropriate environmental cues or guidance to direct cell behavior. It is argued here that present knowledge of tissue repair biology points us toward the latter approach, providing external cues which will direct how cells should organize the new tissue. This will be particularly true where we need to reproduce microscopic and ultrastructural features of the original tissue architecture. A number of such cues have been identified, and methods are already available, including substrate chemistry, substrate contact guidance, mechanical loading, and biochemical mediators to provide these cues. Examples of these are already being used with some success to control the formation of tissue structures.

  5. Mechanical engineer's handbook

    CERN Document Server

    Marghitu, Dan B

    2001-01-01

    The Mechanical Engineer's Handbook was developed and written specifically to fill a need for mechanical engineers and mechanical engineering students throughout the world. With over 1000 pages, 550 illustrations, and 26 tables the Mechanical Engineer's Handbook is very comprehensive, yet affordable, compact, and durable. The Handbook covers all major areas of mechanical engineering with succinct coverage of the definitions, formulas, examples, theory, proofs, and explanations of all principle subject areas. The Handbook is an essential, practical companion for all mechanic

  6. DNA base excision repair nanosystem engineering: model development.

    Science.gov (United States)

    Sokhansanj, B A

    2005-01-01

    DNA base damage results from a combination of endogenous sources, (normal metabolism, increased metabolism due to obesity, stress from diseases such as arthritis and diabetes, and ischemia) and the environment (ingested toxins, ionizing radiation, etc.). If unrepaired DNA base damage can lead to diminished cell function, and potentially diseases and eventually mutations that lead to cancer. Sophisticated DNA repair mechanisms have evolved in all living cells to preserve the integrity of inherited genetic information and transcriptional control. Understanding a system like DNA repair is greatly enhanced by using engineering methods, in particular modeling interactions and using predictive simulation to analyze the impact of perturbations. We describe the use of such a "nanosystem engineering" approach to analyze the DNA base excision repair pathway in human cells, and use simulation to predict the impact of varying enzyme concentration on DNA repair capacity.

  7. Mechanical engineering education

    CERN Document Server

    Davim, J Paulo

    2012-01-01

    Mechanical Engineering is defined nowadays as a discipline "which involves the application of principles of physics, design, manufacturing and maintenance of mechanical systems". Recently, mechanical engineering has also focused on some cutting-edge subjects such as nanomechanics and nanotechnology, mechatronics and robotics, computational mechanics, biomechanics, alternative energies, as well as aspects related to sustainable mechanical engineering.This book covers mechanical engineering higher education with a particular emphasis on quality assurance and the improvement of academic

  8. Tokamak engineering mechanics

    CERN Document Server

    Song, Yuntao; Du, Shijun

    2013-01-01

    Tokamak Engineering Mechanics offers concise and thorough coverage of engineering mechanics theory and application for tokamaks, and the material is reinforced by numerous examples. Chapter topics include general principles, static mechanics, dynamic mechanics, thermal fluid mechanics and multiphysics structural mechanics of tokamak structure analysis. The theoretical principle of the design and the methods of the analysis for various components and load conditions are presented, while the latest engineering technologies are also introduced. The book will provide readers involved in the study

  9. Repair of sciatic nerve defects using tissue engineered nerves*

    Institute of Scientific and Technical Information of China (English)

    Caishun Zhang; Gang Lv

    2013-01-01

    In this study, we constructed tissue-engineered nerves with acel ular nerve al ografts in Sprague-Dawley rats, which were prepared using chemical detergents-enzymatic digestion and mechanical methods, in combination with bone marrow mesenchymal stem cel s of Wistar rats cultured in vitro, to repair 15 mm sciatic bone defects in Wistar rats. At postoperative 12 weeks, electrophysiological detection results showed that the conduction velocity of regenerated nerve after repair with tis-sue-engineered nerves was similar to that after autologous nerve grafting, and was higher than that after repair with acel ular nerve al ografts. Immunohistochemical staining revealed that motor endplates with acetylcholinesterase-positive nerve fibers were orderly arranged in the middle and superior parts of the gastrocnemius muscle;regenerated nerve tracts and sprouted branches were connected with motor endplates, as shown by acetylcholinesterase histochemistry combined with silver staining. The wet weight ratio of the tibialis anterior muscle at the affected contralateral hind limb was similar to the sciatic nerve after repair with autologous nerve grafts, and higher than that after repair with acel ular nerve al ografts. The hind limb motor function at the affected side was significantly improved, indicating that acel ular nerve al ografts combined with bone marrow me-senchymal stem cel bridging could promote functional recovery of rats with sciatic nerve defects.

  10. Mechanical engineers data handbook

    CERN Document Server

    Carvill, James

    1994-01-01

    This text provides the student and professional mechanical engineer with a reference text of an essentially practical nature. It is uncluttered by text, and extensive use of illustrations and tables provide quick and clear access to information. It alsoincludes examples of detailed calculations on many of the applications of technology used by mechanical and production engineers, draughtsmen and engineering designers.Although mainly intended for those studying and practising mechanical engineering, a glance at the contents will show that it is also useful to those in related br

  11. Mechanical engineers' handbook, materials and engineering mechanics

    CERN Document Server

    Kutz, Myer

    2015-01-01

    Full coverage of materials and mechanical design inengineering Mechanical Engineers' Handbook, Fourth Edition provides aquick guide to specialized areas you may encounter in your work,giving you access to the basics of each and pointing you towardtrusted resources for further reading, if needed. The accessibleinformation inside offers discussions, examples, and analyses ofthe topics covered. This first volume covers materials and mechanical design, givingyou accessible and in-depth access to the most common topics you'llencounter in the discipline: carbon and alloy steels, stainlesssteels, a

  12. Quantum mechanical Carnot engine

    CERN Document Server

    Bender, C M; Meister, B K

    2000-01-01

    A cyclic thermodynamic heat engine runs most efficiently if it is reversible. Carnot constructed such a reversible heat engine by combining adiabatic and isothermal processes for a system containing an ideal gas. Here, we present an example of a cyclic engine based on a single quantum-mechanical particle confined to a potential well. The efficiency of this engine is shown to equal the Carnot efficiency because quantum dynamics is reversible. The quantum heat engine has a cycle consisting of adiabatic and isothermal quantum processes that are close analogues of the corresponding classical processes.

  13. Mechanical and Aerospace Engineering

    OpenAIRE

    Millsaps, Knox T.; Gordis, J. H.; Brophy, C. M.; Stephens, Sandra

    2008-01-01

    This brochure explains the Mechanical and Aerospace Engineering program at the Naval Postgraduate School. Sections include: Advancing your career, student research, degree programs, special programs, research and distance learning programs. The Mechanical and Aerospace Engineering (MAE) Department, the founding department of the Naval Postgraduate School in 1909, offers a wide range of graduate degree programs including M.S. and Ph.D., in either Mechanical or Astronautical En...

  14. Mechanical properties of hyaline and repair cartilage studied by nanoindentation.

    Science.gov (United States)

    Franke, O; Durst, K; Maier, V; Göken, M; Birkholz, T; Schneider, H; Hennig, F; Gelse, K

    2007-11-01

    Articular cartilage is a highly organized tissue that is well adapted to the functional demands in joints but difficult to replicate via tissue engineering or regeneration. Its viscoelastic properties allow cartilage to adapt to both slow and rapid mechanical loading. Several cartilage repair strategies that aim to restore tissue and protect it from further degeneration have been introduced. The key to their success is the quality of the newly formed tissue. In this study, periosteal cells loaded on a scaffold were used to repair large partial-thickness cartilage defects in the knee joint of miniature pigs. The repair cartilage was analyzed 26 weeks after surgery and compared both morphologically and mechanically with healthy hyaline cartilage. Contact stiffness, reduced modulus and hardness as key mechanical properties were examined in vitro by nanoindentation in phosphate-buffered saline at room temperature. In addition, the influence of tissue fixation with paraformaldehyde on the biomechanical properties was investigated. Although the repair process resulted in the formation of a stable fibrocartilaginous tissue, its contact stiffness was lower than that of hyaline cartilage by a factor of 10. Fixation with paraformaldehyde significantly increased the stiffness of cartilaginous tissue by one order of magnitude, and therefore, should not be used when studying biomechanical properties of cartilage. Our study suggests a sensitive method for measuring the contact stiffness of articular cartilage and demonstrates the importance of mechanical analysis for proper evaluation of the success of cartilage repair strategies.

  15. Auto Mechanics. Heavy Equipment. Small Engines.

    Science.gov (United States)

    Finnerty, Kathy

    Developed for use in auto mechanics, Heavy Equipment Repair and Operation (HERO), and small engines programs, these study guides and supplemental worksheets cover operating principles, lubrication, cooling system, ignition circuit and electrical system, and fuel system. The worksheets and guide questions are phrased to emphasize key points…

  16. Mechanical design engineering handbook

    CERN Document Server

    Childs, Peter R N

    2013-01-01

    Mechanical Design Engineering Handbook is a straight-talking and forward-thinking reference covering the design, specification, selection, use and integration of machine elements fundamental to a wide range of engineering applications. Develop or refresh your mechanical design skills in the areas of bearings, shafts, gears, seals, belts and chains, clutches and brakes, springs, fasteners, pneumatics and hydraulics, amongst other core mechanical elements, and dip in for principles, data and calculations as needed to inform and evaluate your on-the-job decisions. Covering the full spectrum

  17. Engineering quantum mechanics

    CERN Document Server

    Ahn, Doyeol

    2011-01-01

    A clear introduction to quantum mechanics concepts Quantum mechanics has become an essential tool for modern engineering, particularly due to the recent developments in quantum computing as well as the rapid progress in optoelectronic devices. Engineering Quantum Mechanics explains the fundamentals of this exciting field, providing broad coverage of both traditional areas such as semiconductor and laser physics as well as relatively new yet fast-growing areas such as quantum computation and quantum information technology. The book begins with basic quantum mechanics, reviewing measurements and probability, Dirac formulation, the uncertainty principle, harmonic oscillator, angular momentum eigenstates, and perturbation theory. Then, quantum statistical mechanics is explored, from second quantization and density operators to coherent and squeezed states, coherent interactions between atoms and fields, and the Jaynes-Cummings model. From there, the book moves into elementary and modern applications, discussing s...

  18. Mechanical engineer's reference book

    CERN Document Server

    Parrish, A

    1973-01-01

    Mechanical Engineer's Reference Book: 11th Edition presents a comprehensive examination of the use of Systéme International d' Unités (SI) metrication. It discusses the effectiveness of such a system when used in the field of engineering. It addresses the basic concepts involved in thermodynamics and heat transfer. Some of the topics covered in the book are the metallurgy of iron and steel; screw threads and fasteners; hole basis and shaft basis fits; an introduction to geometrical tolerancing; mechanical working of steel; high strength alloy steels; advantages of making components as castings

  19. Careers Canada. Volume 3, Mechanical Repair Occupations.

    Science.gov (United States)

    Department of Manpower and Immigration, Ottawa (Ontario).

    This pamphlet, published by the Canadian Department of Manpower and Immigration, is the third of a Careers-Canada series and describes careers in mechanical repair occupations. The pamphlet is divided into eight major sections: (1) history and importance; (2) fields of work; (3) nature of work (this section is subdivided into automotive repair…

  20. Mechanical Engineering for Electronics.

    OpenAIRE

    Was, Loïc

    2012-01-01

    Schlumberger drilling tools are exposed to very hard loading conditions (shocks, vibrations, thermal cycling) while performing a job. As these tools are full of electronics, issues can quickly come from electronics failure. Mechanisms of failure occurring in electronics are very complex but can be predicted in some cases. The first part of the thesis describes in which context mechanical engineering applied to electronics is used in Schlumberger. The different kinds of failure which will be i...

  1. Mechanical engineering principles

    CERN Document Server

    Bird, John

    2014-01-01

    A student-friendly introduction to core engineering topicsThis book introduces mechanical principles and technology through examples and applications, enabling students to develop a sound understanding of both engineering principles and their use in practice. These theoretical concepts are supported by 400 fully worked problems, 700 further problems with answers, and 300 multiple-choice questions, all of which add up to give the reader a firm grounding on each topic.The new edition is up to date with the latest BTEC National specifications and can also be used on undergraduate courses in mecha

  2. ADJUSTMENT, MAINTENANCE, AND REPAIR OF SMALL GASOLINE ENGINES. AGRICULTURAL MACHINERY--SERVICE OCCUPATIONS, MODULE NUMBER 12.

    Science.gov (United States)

    Ohio State Univ., Columbus. Center for Vocational and Technical Education.

    ONE OF A SERIES DESIGNED TO HELP TEACHERS PREPARE POSTSECONDARY STUDENTS FOR THE AGRICULTURAL MACHINERY SERVICE OCCUPATIONS AS PARTS MEN, MECHANICS, MECHANIC'S HELPERS, OR SERVICE SUPERVISORS, THIS GUIDE AIMS TO DEVELOP STUDENT COMPETENCY IN THE ADJUSTMENT, MAINTENANCE, AND REPAIR OF SMALL GASOLINE ENGINES. IT WAS DEVELOPED BY A NATIONAL TASK…

  3. Mechanical engineering in hospitals.

    Science.gov (United States)

    Wallington, J W

    1980-10-01

    The design of a modern hospital owes more to engineering than the layman may realize. In this context, many engineers are in the position of laymen, being unfamiliar with the multitude of services that lies behind the impressive facade of a modern hospital. In recent years medicine and surgery themselves have taken on many of the characteristics of a technology. This has required a matching development of the services both mechanical and electrical that are required in modern health care buildings. In medical terms, if the architectural features provide the 'skin' of the hospital, the mechanical and electrical engineering services provide the nerves and sinews. If we take as an example the recently completed Freeman Hospital, Newcastle upon Tyne, (Fig. 1), which cost 10 million pounds at current cost, the service network was responsible for about half the total cost. About 400 miles (643 km) of electrical wiring and more than 40 mile (64.5 km) of copper and steel piping were used to service 3000 separate rooms. This compares with percentages of between 18 and 25 per cent for other large buildings such as office blocks, hotels and sports complexes.

  4. Technology of laser repair welding of nickel superalloy inner flaps of jet engine

    Directory of Open Access Journals (Sweden)

    A. Klimpel

    2011-07-01

    Full Text Available Purpose: of this paper: work out laser welding repair technology of cracked MIG 29 jet engine inner flaps made of cast nickel superalloy ŻS-3DK (ЖС-3ДК, Russian designation.Design/methodology/approach: The study were based on the analysis of laser HPDL powder INCONEL 625 welding of nickel superalloy using wide range of welding parameters to provide highest quality repair welds.Findings: Study of automatic welding technologies GTA, PTA and laser HPDL has shown that just laser welding can provide high quality repair welds. In order to establish the properties of welded joints repair cracks in the inner flap HPDL laser, studied the hardness, mechanical properties and erosive wear resistance.Research limitations/implications: It was found that only laser HPDL welding can provide high quality repair welds.Practical implications: The technology can be applied for repair cracked MIG 29 jet engine inner flaps.Originality/value: Repairing cracked MIG 29 jet engine inner flaps.

  5. Manipulating DNA repair for improved genetic engineering in Aspergillus

    DEFF Research Database (Denmark)

    Nødvig, Christina Spuur

    engineering strategies. Chapter 1 gives an introduction to the genus Aspergillus and some of the tools relevant to fungal genetic engineering. It also contains a short introduction to DNA repair and its interplay with gene targeting and finally an overview over the different genome editing technologies......Aspergillus is a genus of filamentous fungi, which members includes industrial producers of enzymes, organic acids and secondary metabolites, important pathogens and a model organism. As such no matter the specific area of interest there are many reasons to perform genetic engineering, whether...... it is metabolic engineering to create better performing cell factory, elucidating pathways to study secondary metabolism etc. In this thesis, the main focus is on different ways to manipulate DNA repair for optimizing gene targeting, ultimately improving the methods available for faster and better genetic...

  6. Lubrication System. Teacher's Guide. Small Engine Repair Series. First Edition.

    Science.gov (United States)

    Hill, Pamela

    This teacher's guide accompanies three student manuals and together with them comprises an instructional package on the lubrication system in the Small Engine Repair Series for handicapped/special needs students. The first section, "Notes to the Instructor," covers equipment needs, preparation before teaching the instructional package,…

  7. REPAIR MECHANISM IN FOREIGN LANGUAGE CLASSROOM INTERACTION

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    This paper presents practical research on repair mechanismand its four repair trajectories in FL classroom interaction. Thisshows that it is effective and efficient in assisting FL learners todevelop their communicative competence and understand theprocess of language acquisition. Repair strategies that are ofgreat value to FL teachers in FL classroom teaching are also ex-pounded.

  8. Job Prospects for Mechanical Engineers.

    Science.gov (United States)

    Basta, Nicholas

    1986-01-01

    Discusses the career outlook for mechanical engineers. Explains that the number of bachelor degrees awarded yearly has reached a plateau, but salaries continue to rise. Suggests that the largest increase in demand for mechanical engineers will come from industries involved in automation, particularly those developing robotics. (TW)

  9. Springer handbook of mechanical engineering

    Energy Technology Data Exchange (ETDEWEB)

    Grote, Karl-Heinrich [Magdeburg Univ. (Germany). Dept. of Mechanical Engineering; Antonsson, Erik K. (eds.) [California Inst. of Technology (CALTEC), Pasadena, CA (United States). Dept. of Mechanical Engineering

    2009-07-01

    Mechanical Engineering is a professional engineering discipline which involves the application of principles of physics, design, manufacturing and maintenance of mechanical systems. It requires a solid understanding of the key concepts including mechanics, kinematics, thermodynamics and energy. Mechanical engineers use these principles and others in the design and analysis of automobiles, aircrafts, heating and cooling systems, industrial equipment and machinery. In addition to these main areas, specialized fields are necessary to prepare future engineers for their positions in industry, such as mechatronics and robotics, transportation and logistics, fuel technology, automotive engineering, biomechanics, vibration, optics and others. Accordingly, the Springer Handbook of Mechanical Engineering devotes its contents to all areas of interest for the practicing engineer as well as for the student at various levels and educational institutions. Authors from all over the world have contributed with their expertise and support the globally working engineer in finding a solution for today's mechanical engineering problems. Each subject is discussed in detail and supported by numerous figures and tables. DIN standards are retained throughout and ISO equivalents are given where possible. The text offers a concise but detailed and authoritative treatment of the topics with full references. (orig.)

  10. System dynamics for mechanical engineers

    CERN Document Server

    Davies, Matthew

    2015-01-01

    This textbook is ideal for mechanical engineering students preparing to enter the workforce during a time of rapidly accelerating technology, where they will be challenged to join interdisciplinary teams. It explains system dynamics using analogies familiar to the mechanical engineer while introducing new content in an intuitive fashion. The fundamentals provided in this book prepare the mechanical engineer to adapt to continuous technological advances with topics outside traditional mechanical engineering curricula by preparing them to apply basic principles and established approaches to new problems. This book also: ·         Reinforces the connection between the subject matter and engineering reality ·         Includes an instructor pack with the online publication that describes in-class experiments with minimal preparation requirements ·         Provides content dedicated to the modeling of modern interdisciplinary technological subjects, including opto-mechanical systems, high...

  11. Genome engineering with TALENs and ZFNs: repair pathways and donor design.

    Science.gov (United States)

    Carroll, Dana; Beumer, Kelly J

    2014-09-01

    Genome engineering with targetable nucleases depends on cellular pathways of DNA repair after target cleavage. Knowledge of how those pathways work, their requirements and their active factors, can guide experimental design and improve outcomes. While many aspects of both homologous recombination (HR) and nonhomologous end joining (NHEJ) are shared by a broad range of cells and organisms, some features are specific to individual situations. This article reviews the influence of repair mechanisms on the results of gene targeting experiments, with an emphasis on lessons learned from experiments with Drosophila.

  12. DNA repair mechanisms in C. elegans

    NARCIS (Netherlands)

    Brouwer, K.|info:eu-repo/dai/nl/336462557

    2009-01-01

    DNA is the carrier of genetic information. DNA is constantly damaged by, for example, UV light and X-rays. Cells can utilize a large number of proteins that can repair the damages, thereby avoiding changes in the DNA sequence. Damages that are not repaired result in an increase in the number of muta

  13. AC maintenance and repair manual for diesel engines

    CERN Document Server

    Pallas, Jean-Luc

    2013-01-01

    The aim of this book with its detailed step-by-step colour photographs and diagrams, is to enable every owner to fix their diesel engine with ease. Troubleshooting tables help diagnose potential problems, and there is advice on regular maintenance and winterising and repair. Jean-Luc Pallas's enthusiasm for passing on his knowledge, as well as his clear explanations, precise advice and step-by-step instructions make this a unique book.

  14. Mechanical Engineering Department Technical Review

    Energy Technology Data Exchange (ETDEWEB)

    Carr, R.B.; Denney, R.M. (eds.)

    1981-07-01

    The Mechanical Engineering Department Technical Review is published to inform readers of various technical activities within the Department, promote exchange of ideas, and give credit to personnel who are achieving the results. The report is presented in two parts: technical achievements and publication abstracts. The first is divided into seven sections, each of which reports on an engineering division and its specific activities related to nuclear tests, nuclear explosives, weapons, energy systems, engineering sciences, magnetic fusion, and materials fabrication.

  15. Mechanical Engineering Department technical abstracts

    Energy Technology Data Exchange (ETDEWEB)

    1984-07-01

    The Mechanical Engineering Department publishes abstracts twice a year to inform readers of the broad range of technical activities in the Department, and to promote an exchange of ideas. Details of the work covered by an abstract may be obtained by contacting the author(s). General information about the current role and activities of each of the Department's seven divisions precedes the technical abstracts. Further information about a division's work may be obtained from the division leader, whose name is given at the end of each divisional summary. The Department's seven divisions are as follows: Nuclear Test Engineering Division, Nuclear Explosives Engineering Division, Weapons Engineering Division, Energy Systems Engineering Division, Engineering Sciences Division, Magnetic Fusion Engineering Division and Materials Fabrication Division.

  16. Mechanical Aspects of Tissue Engineering

    OpenAIRE

    Liebschner, Michael; Bucklen, Brandon; Wettergreen, Matthew

    2005-01-01

    Tissue engineering describes an initiative whereby a deficit of tissue may be replaced with an engineered construct, typically thought to be some combination of a structural support element and a cellular element. There are several mechanical aspects that come into play during the design of such a construct. First, the way in which the mechanical behavior of a tissue is characterized varies depending on the tissue type. For example, one would not consider the ultimate strength of a non–load-b...

  17. Handbook of mechanical engineering terms

    CERN Document Server

    Ramalingam, KK

    2009-01-01

    About the Book: The Handbook of Mechanical Engineering terms contains short, precise definitions of about four thousand terms. These terms have been collected from different sources, edited and grouped under twenty six parts and given alphabetically under each part for easy reference. The book will be a source of guidance and help to the students, staff and practising engineers in understanding and updating the subject matter. Contents: The Handbook of Mechanical Engineering terms contains short, precise definitions of about four thousand terms. These terms have been collected from differ

  18. The Stirling engine mechanism optimization

    Directory of Open Access Journals (Sweden)

    Jiří Podešva

    2016-03-01

    Full Text Available A special type of the gas engine with external combustion is called Stirling engine. The mechanism has two pistons with two volumes inside. The pistons are connected together through cooler, regenerator and warmer. The engine effectivity depends on the piston movement behaviour. The usual sinusoidal time curve leads to low effectiveness. The quick movement from lower to upper position with a certain delay in both top and bottom dead centres is more effective. The paper deals with three types of mechanisms, analyzing the piston movement, and their behavior. Special emphasize is taken to the piston movement regime.

  19. Basic Mechanics with Engineering Applications

    CERN Document Server

    Jones, J; Fawcett, J N

    2012-01-01

    This book gives a sufficient grounding in mechanics for engineers to tackle a significant range of problems encountered in the design and specification of simple structures and machines. It also provides an excellent background for students wishing to progress to more advanced studies in three-dimensional mechanics.

  20. Wound repair and regeneration: Mechanisms, signaling, and translation

    Science.gov (United States)

    Eming, Sabine A.; Martin, Paul; Tomic-Canic, Marjana

    2015-01-01

    The cellular and molecular mechanisms underpinning tissue repair and its failure to heal are still poorly understood, and current therapies are limited. Poor wound healing after trauma, surgery, acute illness, or chronic disease conditions affects millions of people worldwide each year and is the consequence of poorly regulated elements of the healthy tissue repair response, including inflammation, angiogenesis, matrix deposition, and cell recruitment. Failure of one or several of these cellular processes is generally linked to an underlying clinical condition, such as vascular disease, diabetes, or aging, which are all frequently associated with healing pathologies. The search for clinical strategies that might improve the body’s natural repair mechanisms will need to be based on a thorough understanding of the basic biology of repair and regeneration. In this review, we highlight emerging concepts in tissue regeneration and repair, and provide some perspectives on how to translate current knowledge into viable clinical approaches for treating patients with wound-healing pathologies. PMID:25473038

  1. Repair of osteochondral defects with allogeneic tissue engineered cartilage implants.

    Science.gov (United States)

    Schreiber, R E; Ilten-Kirby, B M; Dunkelman, N S; Symons, K T; Rekettye, L M; Willoughby, J; Ratcliffe, A

    1999-10-01

    The objective of this study was to evaluate the effect of allogeneic tissue engineered cartilage implants on healing of osteochondral defects. Rabbit chondrocytes were cultured in monolayer, then seeded onto biodegradable, three-dimensional polyglycolic acid meshes. Cartilage constructs were cultured hydrodynamically to yield tissue with relatively more (mature) or less (immature) hyalinelike cartilage, as compared with adult rabbit articular cartilage. Osteochondral defects in the patellar grooves of both stifle joints either were left untreated or implanted with allogeneic tissue engineered cartilage. Histologic samples from in and around the defect sites were examined 3, 6, 9, and 12, and 24 months after surgery. By 9 months after surgery, defects sites treated with cartilage implants contained significantly greater amounts of hyalinelike cartilage with high levels of proteoglycan, and had a smooth, nonfibrillated articular surface as compared to untreated defects. In contrast, the repair tissue formed in untreated defects had fibrillated articular surfaces, significant amounts of fibrocartilage, and negligible proteoglycan. These differences between treated and untreated defects persisted through 24 months after surgery. The results of this study suggest that the treatment of osteochondral lesions with allogenic tissue engineered cartilage implants may lead to superior repair tissue than that found in untreated osteochondral lesions.

  2. Detection of abnormalities in the superficial zone of cartilage repaired using a tissue engineered construct derived from synovial stem cells

    OpenAIRE

    Ando, W.; FUJIE, H; Moriguchi, Y.; Nansai, R.; Shimomura, K.; DA Hart; Yoshikawa, H; Nakamura, N.

    2012-01-01

    The present study investigated the surface structure and mechanical properties of repair cartilage generated from a tissue engineered construct (TEC) derived from synovial mesenchymal stem cells at six months post-implantation compared to those of uninjured cartilage. TEC-mediated repair tissue was cartilaginous with Safranin O staining, and had comparable macro-scale compressive properties with uninjured cartilage. However, morphological assessments revealed that the superficial zone of TEC-...

  3. DEVELOPMENT OF PERMANENT MECHANICAL REPAIR SLEEVE FOR PLASTIC PIPE

    Energy Technology Data Exchange (ETDEWEB)

    Hitesh Patadia

    2004-09-30

    The report presents a comprehensive summary of the project status related to the development of a permanent mechanical repair fitting intended to be installed on damaged PE mains under blowing gas conditions. Specifically, the product definition has been developed taking into account relevant codes and standards and industry input. A conceptual design for the mechanical repair sleeve has been developed which meets the product definition.

  4. Improved repair of bone defects with prevascularized tissue-engineered bones constructed in a perfusion bioreactor.

    Science.gov (United States)

    Li, De-Qiang; Li, Ming; Liu, Pei-Lai; Zhang, Yuan-Kai; Lu, Jian-Xi; Li, Jian-Min

    2014-10-01

    Vascularization of tissue-engineered bones is critical to achieving satisfactory repair of bone defects. The authors investigated the use of prevascularized tissue-engineered bone for repairing bone defects. The new bone was greater in the prevascularized group than in the non-vascularized group, indicating that prevascularized tissue-engineered bone improves the repair of bone defects. [Orthopedics. 2014; 37(10):685-690.].

  5. Modern mechanical engineering research, development and education

    CERN Document Server

    2014-01-01

    This book covers modern subjects of mechanical engineering such as nanomechanics and nanotechnology, mechatronics and robotics, computational mechanics, biomechanics, alternative energies, sustainability as well as all aspects related with mechanical engineering education. The chapters help enhance the understanding of both the fundamentals of mechanical engineering and its application to the solution of problems in modern industry. This book is suitable for students, both in final undergraduate mechanical engineering courses or at the graduate level. It also serves as a useful reference for academics, mechanical engineering researchers, mechanical, materials and manufacturing engineers, professionals in related with mechanical engineering.

  6. Engineering science and mechanics department head named

    OpenAIRE

    2004-01-01

    Ishwar K. Puri, professor of mechanical engineering and executive associate dean of engineering at the University of Illinois at Chicago, will become the head of Virginia Tech•À_ó»s Department of Engineering Science and Mechanics Aug. 1.

  7. Head of Department of Mechanical Engineering appointed

    OpenAIRE

    Nystrom, Lynn A.

    2004-01-01

    Kenneth S. Ball, professor of mechanical engineering at the University of Texas at Austin, will become the head of the Department of Mechanical Engineering in Virginia Tech's College of Engineering Aug. 1.

  8. Head of Department of Mechanical Engineering appointed

    OpenAIRE

    Nystrom, Lynn A.

    2004-01-01

    Kenneth S. Ball, professor of mechanical engineering at the University of Texas at Austin, will become the head of the Department of Mechanical Engineering in Virginia Tech's College of Engineering Aug. 1.

  9. Perspectives of ukrainian mechanical engineering development

    OpenAIRE

    Dyrda, Evgenia; Schepetkova, Anastasiya; Galushko, Olena

    2013-01-01

    Theses are devoted to problems and perspectives of Ukrainian mechanical engineering development. Role of mechanical engineering in national economy is described. Problems of mechanical engineering, such as losing the cometetive advantages, production decreasing, debts growing, ineffective assets structure, are investigated. Influence of European integration process on mechanical engineering enterprises is discussed.

  10. Perspectives of ukrainian mechanical engineering development

    OpenAIRE

    Dyrda, Evgenia; Schepetkova, Anastasiya; Galushko, Olena

    2013-01-01

    Theses are devoted to problems and perspectives of Ukrainian mechanical engineering development. Role of mechanical engineering in national economy is described. Problems of mechanical engineering, such as losing the cometetive advantages, production decreasing, debts growing, ineffective assets structure, are investigated. Influence of European integration process on mechanical engineering enterprises is discussed.

  11. Experimental Observation of the Skeletal Adaptive Repair Mechanism and Bionic Topology Optimization Method

    Directory of Open Access Journals (Sweden)

    Kaysar Rahman

    2014-01-01

    Full Text Available Bone adaptive repair theory considers that the external load is the direct source of bone remodeling; bone achieves its maintenance by remodeling some microscopic damages due to external load during the process. This paper firstly observes CT data from the whole self-repairing process in bone defects in rabbit femur. Experimental result shows that during self-repairing process there exists an interaction relationship between spongy bone and enamel bone volume changes of bone defect, that is when volume of spongy bone increases, enamel bone decreases, and when volume of spongy bone decreases, enamel bone increases. Secondly according to this feature a bone remodeling model based on cross-type reaction-diffusion system influenced by mechanical stress is proposed. Finally, this model coupled with finite element method by using the element adding and removing process is used to simulate the self-repairing process and engineering optimization problems by considering the idea of bionic topology optimization.

  12. Quantum Mechanics for Electrical Engineers

    CERN Document Server

    Sullivan, Dennis M

    2011-01-01

    The main topic of this book is quantum mechanics, as the title indicates.  It specifically targets those topics within quantum mechanics that are needed to understand modern semiconductor theory.   It begins with the motivation for quantum mechanics and why classical physics fails when dealing with very small particles and small dimensions.  Two key features make this book different from others on quantum mechanics, even those usually intended for engineers:   First, after a brief introduction, much of the development is through Fourier theory, a topic that is at

  13. Biodegradable Materials for Bone Repair and Tissue Engineering Applications

    Directory of Open Access Journals (Sweden)

    Zeeshan Sheikh

    2015-08-01

    Full Text Available This review discusses and summarizes the recent developments and advances in the use of biodegradable materials for bone repair purposes. The choice between using degradable and non-degradable devices for orthopedic and maxillofacial applications must be carefully weighed. Traditional biodegradable devices for osteosynthesis have been successful in low or mild load bearing applications. However, continuing research and recent developments in the field of material science has resulted in development of biomaterials with improved strength and mechanical properties. For this purpose, biodegradable materials, including polymers, ceramics and magnesium alloys have attracted much attention for osteologic repair and applications. The next generation of biodegradable materials would benefit from recent knowledge gained regarding cell material interactions, with better control of interfacing between the material and the surrounding bone tissue. The next generations of biodegradable materials for bone repair and regeneration applications require better control of interfacing between the material and the surrounding bone tissue. Also, the mechanical properties and degradation/resorption profiles of these materials require further improvement to broaden their use and achieve better clinical results.

  14. Molecular mechanisms of DNA repair inhibition by caffeine

    Energy Technology Data Exchange (ETDEWEB)

    Selby, C.P.; Sancar, A. (Univ. of North Carolina School of Medicine, Chapel Hill (USA))

    1990-05-01

    Caffeine potentiates the mutagenic and lethal effects of genotoxic agents. It is thought that this is due, at least in some organisms, to inhibition of DNA repair. However, direct evidence for inhibition of repair enzymes has been lacking. Using purified Escherichia coli DNA photolyase and (A)BC excinuclease, we show that the drug inhibits photoreactivation and nucleotide excision repair by two different mechanisms. Caffeine inhibits photoreactivation by interfering with the specific binding of photolyase to damaged DNA, and it inhibits nucleotide excision repair by promoting nonspecific binding of the damage-recognition subunit, UvrA, of (A)BC excinuclease. A number of other intercalators, including acriflavin and ethidium bromide, appear to inhibit the excinuclease by a similar mechanism--that is, by trapping the UvrA subunit in nonproductive complexes on undamaged DNA.

  15. Self-Repairing of Chinese Science and Engineering Majors in Oral English

    Science.gov (United States)

    Wang, Weiwei; Xu, Xiaoqin

    2015-01-01

    This study employs corpus analytical tools to carry out a systematic study on Chinese Science and Engineering Majors' (SEMs') use of self-repair in their oral English. The study aims to find out the overall feature of using self-repair by SEMs and to see if there exists statistically significant difference of using self-repair across different…

  16. Platinum drugs and DNA repair mechanisms in lung cancer.

    Science.gov (United States)

    Bonanno, Laura; Favaretto, Adolfo; Rosell, Rafael

    2014-01-01

    The standard first-line treatment for around 80% of newly-diagnosed advanced non-small cell lung cancer (NSCLC) is chemotherapy. Currently, patients are allocated to chemotherapy on the basis of clinical conditions, comorbidities and histology. If feasible, platinum-based chemotherapy is considered as the most efficacious option. Due to the heterogeneity in terms of platinum-sensitivity among patients with NSCLC, great efforts have been made in order to identify molecular predictive markers of platinum resistance. Based on the mechanism of action of platinum, several components of DNA repair pathways have been investigated as potential predictive markers. The main DNA repair pathways involved in the repair of platinum-induced DNA damage are nucleotide excision repair and homologous recombination. The most studied potential predictive markers of platinum-sensitivity are Excision Repair Cross Complementing-1 (ERCC1) and Brest Cancer Type-I Susceptibility protein (BRCA1); however, increasing biological knowledge about DNA repair pathways suggests the potential clinical usefulness of integrated analysis of multiple DNA repair components.

  17. Mechanical Autonomous Stochastic Heat Engine

    Science.gov (United States)

    Serra-Garcia, Marc; Foehr, André; Molerón, Miguel; Lydon, Joseph; Chong, Christopher; Daraio, Chiara

    2016-07-01

    Stochastic heat engines are devices that generate work from random thermal motion using a small number of highly fluctuating degrees of freedom. Proposals for such devices have existed for more than a century and include the Maxwell demon and the Feynman ratchet. Only recently have they been demonstrated experimentally, using, e.g., thermal cycles implemented in optical traps. However, recent experimental demonstrations of classical stochastic heat engines are nonautonomous, since they require an external control system that prescribes a heating and cooling cycle and consume more energy than they produce. We present a heat engine consisting of three coupled mechanical resonators (two ribbons and a cantilever) subject to a stochastic drive. The engine uses geometric nonlinearities in the resonating ribbons to autonomously convert a random excitation into a low-entropy, nonpassive oscillation of the cantilever. The engine presents the anomalous heat transport property of negative thermal conductivity, consisting in the ability to passively transfer energy from a cold reservoir to a hot reservoir.

  18. Mechanisms and functions of DNA mismatch repair

    Institute of Scientific and Technical Information of China (English)

    Guo MinLi

    2008-01-01

    DNA mismatch repair (MMR) is a highly conserved biological pathway that plays a key role in maintaining genomic stability. The specificity of MMR is primarily for base-base mismatches and insertion/deletion mispairs generated dur-ing DNA replication and recombination. MMR also suppresses homeologous recombination and was recently shown to play a role in DNA damage signaling in eukaryotic cells. Escherichia coli MutS and MutL and their eukaryotic homo-logs, MutSα and MutLα, respectively, are key players in MMR-associated genome maintenance. Many other protein components that participate in various DNA metabolic pathways, such as PCNA and RPA, are also essential for MMR. Defects in MMR are associated with genome-wide instability, predisposition to certain types of cancer including he-reditary non-polyposis colorectal cancer, resistance to certain chemotherapeutic agents, and abnormalities in meiosis and sterility in mammalian systems.

  19. Mechanical engineering department technical review

    Energy Technology Data Exchange (ETDEWEB)

    Carr, R.B. Denney, R.M. (eds.)

    1981-01-01

    The Mechanical Engineering Department Technical Review is published to: (1) inform the readers of various technical activities within the department, (2) promote exchange of ideas, and (3) give credit to the personnel who are achieving the results. The report is formatted into two parts: technical acievements and publication abstracts. The first is divided into eight sections, one for each division in the department providing the reader with the names of the personnel and the division accomplishing the work.

  20. Mechanical Engineering Department. Technical review

    Energy Technology Data Exchange (ETDEWEB)

    Simecka, W.B.; Condouris, R.A.; Talaber, C. (eds.)

    1980-01-01

    The Mechanical Engineering Department Technical Review is published to (1) inform the readers of various technical activities within the Department, (2) promote exchange of ideas, and (3) give credit to the personnel who are achieving the results. The report is formatted into two parts: technical achievements and publication abstracts. The first is divided into eight sections, one for each Division in the Department providing the reader with the names of the personnel and the Division accomplishing the work.

  1. Mechanical Engineering Department technical abstracts

    Energy Technology Data Exchange (ETDEWEB)

    Denney, R.M. (ed.)

    1982-07-01

    The Mechanical Engineering Department publishes listings of technical abstracts twice a year to inform readers of the broad range of technical activities in the Department, and to promote an exchange of ideas. Details of the work covered by an abstract may be obtained by contacting the author(s). Overall information about current activities of each of the Department's seven divisions precedes the technical abstracts.

  2. A brief history of mechanical engineering

    CERN Document Server

    Dixit, Uday Shanker; Davim, J Paulo

    2017-01-01

    What is mechanical engineering? What a mechanical engineering does? How did the mechanical engineering change through ages? What is the future of mechanical engineering? This book answers these questions in a lucid manner. It also provides a brief chronological history of landmark events and answers questions such as: When was steam engine invented? Where was first CNC machine developed? When did the era of additive manufacturing start? When did the marriage of mechanical and electronics give birth to discipline of mechatronics? This book informs and create interest on mechanical engineering in the general public and particular in students. It also helps to sensitize the engineering fraternity about the historical aspects of engineering. At the same time, it provides a common sense knowledge of mechanical engineering in a handy manner.

  3. Tissue engineering applications: cartilage lesions repair by the use of autologous chondrocytes

    Directory of Open Access Journals (Sweden)

    L. De Franceschi

    2011-09-01

    Full Text Available Promising new therapies based on tissue engineering have been recently developed for cartilage repair. The association of biomaterials with autologous chondrocytes expanded in vitro can represent a useful tool to regenerate this tissue. The scaffolds utilised in such therapeutical applications should provide a pre-formed three-dimensional shape, prevent cells from floating out of the defect, have sufficient mechanical strength, facilitate uniform spread of cells and stimulate the phenotype of transplanted cells. Hyaff®-11 is a hyaluronic-acid based biodegradable polymer, that has been shown to provide successful cell carrier for tissue-engineered repair. From our findings we can state that human chondrocytes seeded on Hyaff®-11 are able to maintain in vitro the characteristic of differentiated cells, expressing and producing collagen type II and aggrecan which are the main markers of cartilage phenotype, down-regulating collagen type I. Moreover, it seems to be a useful scaffold for cartilage repair both in animal models and clinical trials in humans, favouring the formation of a hyaline-like tissue. In the light of these data, we can hypothesise, for the future, the use of autologous chondrocyte transplantation together with gene therapy as a treatment for rheumatic diseases such as osteoarthritis.

  4. Expose Mechanical Engineering Students to Biomechanics Topics

    Science.gov (United States)

    Shen, Hui

    2011-01-01

    To adapt the focus of engineering education to emerging new industries and technologies nationwide and in the local area, a biomechanics module has been developed and incorporated into a mechanical engineering technical elective course to expose mechanical engineering students at ONU (Ohio Northern University) to the biomedical engineering topics.…

  5. Mechanical Engineering Department technical review

    Energy Technology Data Exchange (ETDEWEB)

    Carr, R.B.; Abrahamson, L.; Denney, R.M.; Dubois, B.E (eds.)

    1982-01-01

    Technical achievements and publication abstracts related to research in the following Divisions of Lawrence Livermore Laboratory are reported in this biannual review: Nuclear Fuel Engineering; Nuclear Explosives Engineering; Weapons Engineering; Energy Systems Engineering; Engineering Sciences; Magnetic Fusion Engineering; and Material Fabrication. (LCL)

  6. SMAP Instrument Mechanical System Engineering

    Science.gov (United States)

    Slimko, Eric; French, Richard; Riggs, Benjamin

    2013-01-01

    The Soil Moisture Active Passive (SMAP) mission, scheduled for launch by the end of 2014, is being developed to measure the soil moisture and soil freeze/thaw state on a global scale over a three-year period. The accuracy, resolution, and global coverage of SMAP measurements are invaluable across many science and applications disciplines including hydrology, climate, carbon cycle, and the meteorological, environment, and ecology applications communities. The SMAP observatory is composed of a despun bus and a spinning instrument platform that includes both a deployable 6 meter aperture low structural frequency Astromesh reflector and a spin control system. The instrument section has engendered challenging mechanical system issues associated with the antenna deployment, flexible antenna pointing in the context of a multitude of disturbances, spun section mass properties, spin control system development, and overall integration with the flight system on both mechanical and control system levels. Moreover, the multitude of organizations involved, including two major vendors providing the spin subsystem and reflector boom assembly plus the flight system mechanical and guidance, navigation, and control teams, has led to several unique system engineering challenges. Capturing the key physics associated with the function of the flight system has been challenging due to the many different domains that are applicable. Key interfaces and operational concepts have led to complex negotiations because of the large number of organizations that integrate with the instrument mechanical system. Additionally, the verification and validation concerns associated with the mechanical system have had required far-reaching involvement from both the flight system and other subsystems. The SMAP instrument mechanical systems engineering issues and their solutions are described in this paper.

  7. SMAP Instrument Mechanical System Engineering

    Science.gov (United States)

    Slimko, Eric; French, Richard; Riggs, Benjamin

    2013-01-01

    The Soil Moisture Active Passive (SMAP) mission, scheduled for launch by the end of 2014, is being developed to measure the soil moisture and soil freeze/thaw state on a global scale over a three-year period. The accuracy, resolution, and global coverage of SMAP measurements are invaluable across many science and applications disciplines including hydrology, climate, carbon cycle, and the meteorological, environment, and ecology applications communities. The SMAP observatory is composed of a despun bus and a spinning instrument platform that includes both a deployable 6 meter aperture low structural frequency Astromesh reflector and a spin control system. The instrument section has engendered challenging mechanical system issues associated with the antenna deployment, flexible antenna pointing in the context of a multitude of disturbances, spun section mass properties, spin control system development, and overall integration with the flight system on both mechanical and control system levels. Moreover, the multitude of organizations involved, including two major vendors providing the spin subsystem and reflector boom assembly plus the flight system mechanical and guidance, navigation, and control teams, has led to several unique system engineering challenges. Capturing the key physics associated with the function of the flight system has been challenging due to the many different domains that are applicable. Key interfaces and operational concepts have led to complex negotiations because of the large number of organizations that integrate with the instrument mechanical system. Additionally, the verification and validation concerns associated with the mechanical system have had required far-reaching involvement from both the flight system and other subsystems. The SMAP instrument mechanical systems engineering issues and their solutions are described in this paper.

  8. Industrial Applications of LES in Mechanical Engineering

    Science.gov (United States)

    2001-08-01

    UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADP013624 TITLE: Industrial Applications of LES in Mechanical Engineering DISTRIBUTION...compilation report: ADP013620 thru ADP013707 UNCLASSIFIED INDUSTRIAL APPLICATIONS OF LES IN MECHANICAL ENGINEERING CHISACHI KATO Institute of Industrial...Science University of Tokyo, Tokyo, Japan MASAYUKI KAIHO, AKIRA MANABE Mechanical Engineering Research Laboratory Hitachi LTD., Ibaraki, Japan Abstract

  9. Engineering

    National Research Council Canada - National Science Library

    Includes papers in the following fields: Aerospace Engineering, Agricultural Engineering, Chemical Engineering, Civil Engineering, Electrical Engineering, Environmental Engineering, Industrial Engineering, Materials Engineering, Mechanical...

  10. Self-repair networks a mechanism design

    CERN Document Server

    Ishida, Yoshiteru

    2015-01-01

    This book describes the struggle to introduce a mechanism that enables next-generation information systems to maintain themselves. Our generation observed the birth and growth of information systems, and the Internet in particular. Surprisingly information systems are quite different from conventional (energy, material-intensive) artificial systems, and rather resemble biological systems (information-intensive systems). Many artificial systems are designed based on (Newtonian) physics assuming that every element obeys simple and static rules; however, the experience of the Internet suggests a different way of designing where growth cannot be controlled but self-organized with autonomous and selfish agents. This book suggests using game theory, a mechanism design in particular, for designing next-generation information systems which will be self-organized by collective acts with autonomous components. The challenge of mapping a probability to time appears repeatedly in many forms throughout this book. The book...

  11. Mechanical Engineering Refrigeration Systems for Cold Storage

    Science.gov (United States)

    1981-10-01

    LEVELK NAVFAC-DM -3.4 OCTOBER 1981 ,T O MECHANICAL ENGINEERING let REFRIGERATION SYSTEMS FOR COLD STORAGE * ,DESIGN MANUAL 3.4 APPROVED FOR PUBLIC...NUMBERNAVFAC DM3. 4- TITLE (and Subtlte) S. TYPE OF REPORT & PERIOD COVERED NAVFAC Design Manual DM-3.4 Design Criteria Mechanical Engineering Final...U S.Navy I Naval Facilities Engineering Command I r DT I, - - __ IM, *r 3i 3.4-v MECHANICAL ENGINEERING DESIGN MANUALS Chapter superseded DM Number

  12. Laser Engineered Net Shape (LENS) Technology for the Repair of Ni-Base Superalloy Turbine Components

    Science.gov (United States)

    Liu, Dejian; Lippold, John C.; Li, Jia; Rohklin, Stan R.; Vollbrecht, Justin; Grylls, Richard

    2014-09-01

    The capability of the laser engineered net shape (LENS) process was evaluated for the repair of casting defects and improperly machined holes in gas turbine engine components. Various repair geometries, including indentations, grooves, and through-holes, were used to simulate the actual repair of casting defects and holes in two materials: Alloy 718 and Waspaloy. The influence of LENS parameters, including laser energy density, laser scanning speed, and deposition pattern, on the repair of these defects and holes was studied. Laser surface remelting of the substrate prior to repair was used to remove machining defects and prevent heat-affected zone (HAZ) liquation cracking. Ultrasonic nondestructive evaluation techniques were used as a possible approach for detecting lack-of-fusion in repairs. Overall, Alloy 718 exhibited excellent repair weldability, with essentially no defects except for some minor porosity in repairs representative of deep through-holes and simulated large area casting defects. In contrast, cracking was initially observed during simulated repair of Waspaloy. Both solidification cracking and HAZ liquation cracking were observed in the repairs, especially under conditions of high heat input (high laser power and/or low scanning speed). For Waspaloy, the degree of cracking was significantly reduced and, in most cases, completely eliminated by the combination of low laser energy density and relatively high laser scanning speeds. It was found that through-hole repairs of Waspaloy made using a fine powder size exhibited excellent repair weldability and were crack-free relative to repairs using coarser powder. Simulated deep (7.4 mm) blind-hole repairs, representative of an actual Waspaloy combustor case, were successfully produced by the combination use of fine powder and relatively high laser scanning speeds.

  13. Technical abstracts: Mechanical engineering, 1990

    Energy Technology Data Exchange (ETDEWEB)

    Broesius, J.Y. (comp.)

    1991-03-01

    This document is a compilation of the published, unclassified abstracts produced by mechanical engineers at Lawrence Livermore National Laboratory (LLNL) during the calendar year 1990. Many abstracts summarize work completed and published in report form. These are UCRL-JC series documents, which include the full text of articles to be published in journals and of papers to be presented at meetings, and UCID reports, which are informal documents. Not all UCIDs contain abstracts: short summaries were generated when abstracts were not included. Technical Abstracts also provides descriptions of those documents assigned to the UCRL-MI (miscellaneous) category. These are generally viewgraphs or photographs presented at meetings. An author index is provided at the back of this volume for cross referencing.

  14. Evaluation of histological scoring systems for tissue-engineered, repaired and osteoarthritic cartilage

    NARCIS (Netherlands)

    Rutgers, M.; van Pelt, M.J.; Dhert, W.J.A.; Creemers, L.B.; Saris, D.B.F.

    2010-01-01

    Osteoarthritis and Cartilage Volume 18, Issue 1, January 2010, Pages 12-23 -------------------------------------------------------------------------------- Review Evaluation of histological scoring systems for tissue-engineered, repaired and osteoarthritic cartilage M. Rutgers†, M.J.P. van Pelt†, W.

  15. Evaluation of histological scoring systems for tissue-engineered, repaired and osteoarthritic cartilage

    NARCIS (Netherlands)

    Rutgers, M.; van Pelt, M.J.; Dhert, W.J.A.; Creemers, L.B.; Saris, D.B.F.

    2010-01-01

    Osteoarthritis and Cartilage Volume 18, Issue 1, January 2010, Pages 12-23 -------------------------------------------------------------------------------- Review Evaluation of histological scoring systems for tissue-engineered, repaired and osteoarthritic cartilage M. Rutgers†, M.J.P. van Pelt†,

  16. An end-joining repair mechanism in Escherichia coli

    Science.gov (United States)

    Chayot, Romain; Montagne, Benjamin; Mazel, Didier; Ricchetti, Miria

    2010-01-01

    Bridging broken DNA ends via nonhomologous end-joining (NHEJ) contributes to the evolution and stability of eukaryote genomes. Although some bacteria possess a simplified NHEJ mechanism, the human commensal Escherichia coli is thought to rely exclusively on homology-directed mechanisms to repair DNA double-strand breaks (DSBs). We show here that laboratory and pathogenic E. coli strains possess a distinct end-joining activity that repairs DSBs and generates genome rearrangements. This mechanism, named alternative end-joining (A-EJ), does not rely on the key NHEJ proteins Ku and Ligase-D which are absent in E. coli. Differently from classical NHEJ, A-EJ is characterized by extensive end-resection largely due to RecBCD, by overwhelming usage of microhomology and extremely rare DNA synthesis. We also show that A-EJ is dependent on the essential Ligase-A and independent on Ligase-B. Importantly, mutagenic repair requires a functional Ligase-A. Although generally mutagenic, accurate A-EJ also occurs and is frequent in some pathogenic bacteria. Furthermore, we show the acquisition of an antibiotic-resistance gene via A-EJ, refuting the notion that bacteria gain exogenous sequences only by recombination-dependent mechanisms. This finding demonstrates that E. coli can integrate unrelated, nonhomologous exogenous sequences by end-joining and it provides an alternative strategy for horizontal gene transfer in the bacterial genome. Thus, A-EJ contributes to bacterial genome evolution and adaptation to environmental challenges. Interestingly, the key features of A-EJ also appear in A-NHEJ, an alternative end-joining mechanism implicated in chromosomal translocations associated with human malignancies, and we propose that this mutagenic repair might have originated in bacteria. PMID:20133858

  17. Lubrication System 1. Check and Change the Engine Oil. Student Manual. Small Engine Repair Series. First Edition.

    Science.gov (United States)

    Hill, Pamela

    This student manual on checking and changing the engine oil is the second of three in an instructional package on the lubrication system in the Small Engine Repair Series for handicapped students. The stated purpose for the booklet is to help students learn what tools and equipment to use and all the steps of the job. Informative material and…

  18. Defective DNA repair mechanisms in prostate cancer: impact of olaparib

    Directory of Open Access Journals (Sweden)

    De Felice F

    2017-03-01

    Full Text Available Francesca De Felice,1 Vincenzo Tombolini,1 Francesco Marampon,2 Angela Musella,3 Claudia Marchetti3 1Department of Radiotherapy, Policlinico Umberto I, “Sapienza” University of Rome, Rome, 2Department of Biotechnological and Applied Clinical Sciences, Laboratory of Radiobiology, University of L’Aquila, L’Aquila, 3Department of Gynecological and Obstetrical Sciences and Urological Sciences, “Sapienza” University of Rome, Rome, Italy Abstract: The field of prostate oncology has continued to change dramatically. It has truly become a field that is intensely linked to molecular genetic alterations, especially DNA-repair defects. Germline breast cancer 1 gene (BRCA1 and breast cancer 2 gene (BRCA2 mutations are implicated in the highest risk of prostate cancer (PC predisposition and aggressiveness. Poly adenosine diphosphate ribose polymerase (PARP proteins play a key role in DNA repair mechanisms and represent a valid target for new therapies. Olaparib is an oral PARP inhibitor that blocks DNA repair pathway and coupled with BRCA mutated-disease results in tumor cell death. In phase II clinical trials, including patients with advanced castration-resistant PC, olaparib seems to be efficacious and well tolerated. Waiting for randomized phase III trials, olaparib should be considered as a promising treatment option for PC. Keywords: prostate cancer, metastatic disease, castration resistant, BRCA, DNA-repair, PARP, olaparib

  19. Performance of Engineered Cementitious Composites for Concrete Repairs

    NARCIS (Netherlands)

    Zhou, J.

    2011-01-01

    Background and goals of this thesis The concrete repair, rehabilitation and retrofitting industry grows rapidly, driven by deterioration of, damage to and defects in concrete structures. However, it is well known that to achieve durable concrete repairs is very difficult. The failure of concrete rep

  20. Performance of Engineered Cementitious Composites for Concrete Repairs

    NARCIS (Netherlands)

    Zhou, J.

    2011-01-01

    Background and goals of this thesis The concrete repair, rehabilitation and retrofitting industry grows rapidly, driven by deterioration of, damage to and defects in concrete structures. However, it is well known that to achieve durable concrete repairs is very difficult. The failure of concrete

  1. Performance of Engineered Cementitious Composites for Concrete Repairs

    NARCIS (Netherlands)

    Zhou, J.

    2011-01-01

    Background and goals of this thesis The concrete repair, rehabilitation and retrofitting industry grows rapidly, driven by deterioration of, damage to and defects in concrete structures. However, it is well known that to achieve durable concrete repairs is very difficult. The failure of concrete rep

  2. An Improved Rotary Mechanism Engine

    Directory of Open Access Journals (Sweden)

    M.L Kumar

    1977-01-01

    Full Text Available Developments in the field of rotary engines have been reviewed. Potential of scissor action type rotary engine with suitable innovations on linkage and multirotor configuration has been brought out.

  3. Repair of osteochondral defects with in vitro engineered cartilage based on autologous bone marrow stromal cells in a swine model

    Science.gov (United States)

    He, Aijuan; Liu, Lina; Luo, Xusong; Liu, Yu; Liu, Yi; Liu, Fangjun; Wang, Xiaoyun; Zhang, Zhiyong; Zhang, Wenjie; Liu, Wei; Cao, Yilin; Zhou, Guangdong

    2017-01-01

    Functional reconstruction of large osteochondral defects is always a major challenge in articular surgery. Some studies have reported the feasibility of repairing articular osteochondral defects using bone marrow stromal cells (BMSCs) and biodegradable scaffolds. However, no significant breakthroughs have been achieved in clinical translation due to the instability of in vivo cartilage regeneration based on direct cell-scaffold construct implantation. To overcome the disadvantages of direct cell-scaffold construct implantation, the current study proposed an in vitro cartilage regeneration strategy, providing relatively mature cartilage-like tissue with superior mechanical properties. Our strategy involved in vitro cartilage engineering, repair of osteochondral defects, and evaluation of in vivo repair efficacy. The results demonstrated that BMSC engineered cartilage in vitro (BEC-vitro) presented a time-depended maturation process. The implantation of BEC-vitro alone could successfully realize tissue-specific repair of osteochondral defects with both cartilage and subchondral bone. Furthermore, the maturity level of BEC-vitro had significant influence on the repaired results. These results indicated that in vitro cartilage regeneration using BMSCs is a promising strategy for functional reconstruction of osteochondral defect, thus promoting the clinical translation of cartilage regeneration techniques incorporating BMSCs. PMID:28084417

  4. An introduction to mechanical engineering, pt.2

    CERN Document Server

    Clifford, Michael

    2010-01-01

    An Introduction to Mechanical Engineering: Part 2 is an essential text for all second-year undergraduate students as well as those studying foundation degrees and HNDs. The text provides thorough coverage of the following core engineering topics:Fluid dynamicsThermodynamicsSolid mechanicsControl theory and techniquesMechanical power, loads and transmissionsStructural vibrationAs well as mechanical engineers, the text will be highly relevant to automotive, aeronautical/aerospace and general engineering students.The material in this book has full student and lecturer support on an accompanying w

  5. An introduction to mechanical engineering, pt.1

    CERN Document Server

    Clifford, Michael; Shipway, Philip

    2012-01-01

    An Introduction to Mechanical Engineering is an essential text for all first-year undergraduate students as well as those studying for foundation degrees and HNDs. The text gives a thorough grounding in the following core engineering topics: thermodynamics, fluid mechanics, solid mechanics, dynamics, electricals and electronics, and materials science. As well as mechanical engineers, the text will be highly relevant to civil, automotive, aeronautical/aerospace and general engineering students.The text is written by an experienced team of first-year lecturers at the internationally renowned Uni

  6. Teaching Continuum Mechanics in a Mechanical Engineering Program

    Science.gov (United States)

    Liu, Yucheng

    2011-01-01

    This paper introduces a graduate course, continuum mechanics, which is designed for and taught to graduate students in a Mechanical Engineering (ME) program. The significance of continuum mechanics in engineering education is demonstrated and the course structure is described. Methods used in teaching this course such as topics, class…

  7. Teaching Continuum Mechanics in a Mechanical Engineering Program

    Science.gov (United States)

    Liu, Yucheng

    2011-01-01

    This paper introduces a graduate course, continuum mechanics, which is designed for and taught to graduate students in a Mechanical Engineering (ME) program. The significance of continuum mechanics in engineering education is demonstrated and the course structure is described. Methods used in teaching this course such as topics, class…

  8. Mechanical engineering science in SI units

    CERN Document Server

    Gwyther, J L; Williams, G

    1970-01-01

    0.1 Mechanical Engineering Science covers various fundamental concepts that are essential in the practice of mechanical engineering. The title is comprised of 19 chapters that detail various topics, including chemical and physical laws. The coverage of the book includes Newtonian laws, mechanical energy, friction, stress, and gravity. The text also discusses the chemical aspects of mechanical engineering, which include gas laws, states of matter, and fuel combustion. The last chapter tackles concerns in laboratory experiments. The book will be of great use to students of mechanical eng

  9. Small Engine Repair Modules (Workbook) = Reparacion de Motores Pequenos (Guia de Trabajo)

    Science.gov (United States)

    New York State Dept. of Correctional Services, Albany.

    This package contains an English-Language set of task procedure sheets dealing with small-engine repair and a Spanish translation of the same material. Addressed in the individual sections of the manual are the following aspects of engine tune-up, reconditioning, and troubleshooting: servicing air cleaners; cleaning gas tanks, fuel lines, and fuel…

  10. Small Engine Repair Modules (Workbook) = Reparacion de Motores Pequenos (Guia de Trabajo)

    Science.gov (United States)

    New York State Dept. of Correctional Services, Albany.

    This package contains an English-Language set of task procedure sheets dealing with small-engine repair and a Spanish translation of the same material. Addressed in the individual sections of the manual are the following aspects of engine tune-up, reconditioning, and troubleshooting: servicing air cleaners; cleaning gas tanks, fuel lines, and fuel…

  11. Gasoline Engine Mechanics. Florida Vocational Program Guide.

    Science.gov (United States)

    University of South Florida, Tampa. Dept. of Adult and Vocational Education.

    This vocational program guide is intended to assist in the organization, operation, and evaluation of a program in gasoline engine mechanics in school districts, area vocational centers, and community colleges. The following topics are covered: job duties of small-engine mechanics; program content (curriculum framework and student performance…

  12. Things for You to Know. Fuel System. Student Manual--Introduction. Small Engine Repair Series. First Edition.

    Science.gov (United States)

    Hill, Pamela

    This student manual, part of a small-engine repair series on servicing fuel systems, is designed for use by special needs students in Texas. Information covered in this manual is considered to be the minimum that students need to know about fuel systems in order to get small-engine repair jobs. The manual introduces students to small-engine fuel…

  13. 46 CFR 167.65-70 - Reports of accidents, repairs, and unsafe boilers and machinery by engineers.

    Science.gov (United States)

    2010-10-01

    ... machinery by engineers. 167.65-70 Section 167.65-70 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY... of accidents, repairs, and unsafe boilers and machinery by engineers. (a) Before making repairs to a... shall be the duty of all engineers when an accident occurs to the boilers or machinery in their...

  14. A high throughput mechanical screening device for cartilage tissue engineering.

    Science.gov (United States)

    Mohanraj, Bhavana; Hou, Chieh; Meloni, Gregory R; Cosgrove, Brian D; Dodge, George R; Mauck, Robert L

    2014-06-27

    Articular cartilage enables efficient and near-frictionless load transmission, but suffers from poor inherent healing capacity. As such, cartilage tissue engineering strategies have focused on mimicking both compositional and mechanical properties of native tissue in order to provide effective repair materials for the treatment of damaged or degenerated joint surfaces. However, given the large number design parameters available (e.g. cell sources, scaffold designs, and growth factors), it is difficult to conduct combinatorial experiments of engineered cartilage. This is particularly exacerbated when mechanical properties are a primary outcome, given the long time required for testing of individual samples. High throughput screening is utilized widely in the pharmaceutical industry to rapidly and cost-effectively assess the effects of thousands of compounds for therapeutic discovery. Here we adapted this approach to develop a high throughput mechanical screening (HTMS) system capable of measuring the mechanical properties of up to 48 materials simultaneously. The HTMS device was validated by testing various biomaterials and engineered cartilage constructs and by comparing the HTMS results to those derived from conventional single sample compression tests. Further evaluation showed that the HTMS system was capable of distinguishing and identifying 'hits', or factors that influence the degree of tissue maturation. Future iterations of this device will focus on reducing data variability, increasing force sensitivity and range, as well as scaling-up to even larger (96-well) formats. This HTMS device provides a novel tool for cartilage tissue engineering, freeing experimental design from the limitations of mechanical testing throughput.

  15. Eukaryotic nucleotide excision repair: from understanding mechanisms to influencing biology

    Institute of Scientific and Technical Information of China (English)

    Sarah C Shuck; Emily A Short; John J Turchi

    2008-01-01

    Repair of bulky DNA adducts by the nucleotide excision repair (NER) pathway is one of the more versatile DNA repair pathways for the removal of DNA lesions. There are two subsets of the NER pathway, global genomic-NER (GG-NER) and transcription-coupled NER (TC-NER), which differ only in the step involving recognition of the DNA lesion. Following recognition of the damage, the sub-pathways then converge for the incision/excision steps and subsequent gap filling and ligation steps. This review will focus on the GGR sub-pathway of NER while the TCR sub-pathway will be covered in another article in this issue. The ability of the NER pathway to repair a wide array of adducts stems, in part, from the mechanisms involved in the initial recognition step of the damaged DNA and results in NER impacting an equally wide array of human physiological responses and events. In this review, the impact of NER on carcinogenesis, neurological function, sensitivity to environmental factors and sensitivity to cancer therapeutics will be discussed. The knowledge generated in our understanding of the NER pathway over the past 40 years has resulted from advances in the fields of animal model systems, mammalian genetics and in vitro biochemistry, as well as from reconstitution studies and structural analyses of the proteins and enzymes that participate in this pathway. Each of these avenues of research has contributed significantly to our understanding of how the NER pathway works and how alterations in NER activity, both positive and negative, influence human biology.

  16. Mechanical autonomous stochastic heat engines

    Science.gov (United States)

    Serra-Garcia, Marc; Foehr, Andre; Moleron, Miguel; Lydon, Joseph; Chong, Christopher; Daraio, Chiara; . Team

    Stochastic heat engines extract work from the Brownian motion of a set of particles out of equilibrium. So far, experimental demonstrations of stochastic heat engines have required extreme operating conditions or nonautonomous external control systems. In this talk, we will present a simple, purely classical, autonomous stochastic heat engine that uses the well-known tension induced nonlinearity in a string. Our engine operates between two heat baths out of equilibrium, and transfers energy from the hot bath to a work reservoir. This energy transfer occurs even if the work reservoir is at a higher temperature than the hot reservoir. The talk will cover a theoretical investigation and experimental results on a macroscopic setup subject to external noise excitations. This system presents an opportunity for the study of non equilibrium thermodynamics and is an interesting candidate for innovative energy conversion devices.

  17. Selection of software for mechanical engineering undergraduates

    Energy Technology Data Exchange (ETDEWEB)

    Cheah, C. T.; Yin, C. S.; Halim, T.; Naser, J.; Blicblau, A. S., E-mail: ablicblau@swin.edu.au [Swinburne University of Technology, Faculty of Science Engineering and Technology, PO Box 218 Hawthorn, Victoria, Australia, 3122 (Australia)

    2016-07-12

    A major problem with the undergraduate mechanical course is the limited exposure of students to software packages coupled with the long learning curve on the existing software packages. This work proposes the use of appropriate software packages for the entire mechanical engineering curriculum to ensure students get sufficient exposure real life design problems. A variety of software packages are highlighted as being suitable for undergraduate work in mechanical engineering, e.g. simultaneous non-linear equations; uncertainty analysis; 3-D modeling software with the FEA; analysis tools for the solution of problems in thermodynamics, fluid mechanics, mechanical system design, and solid mechanics.

  18. Selection of software for mechanical engineering undergraduates

    Science.gov (United States)

    Cheah, C. T.; Yin, C. S.; Halim, T.; Naser, J.; Blicblau, A. S.

    2016-07-01

    A major problem with the undergraduate mechanical course is the limited exposure of students to software packages coupled with the long learning curve on the existing software packages. This work proposes the use of appropriate software packages for the entire mechanical engineering curriculum to ensure students get sufficient exposure real life design problems. A variety of software packages are highlighted as being suitable for undergraduate work in mechanical engineering, e.g. simultaneous non-linear equations; uncertainty analysis; 3-D modeling software with the FEA; analysis tools for the solution of problems in thermodynamics, fluid mechanics, mechanical system design, and solid mechanics.

  19. DNA repair mechanisms in eukaryotes: Special focus in Entamoeba histolytica and related protozoan parasites.

    Science.gov (United States)

    López-Camarillo, César; Lopez-Casamichana, Mavil; Weber, Christian; Guillen, Nancy; Orozco, Esther; Marchat, Laurence A

    2009-12-01

    Eukaryotic cell viability highly relies on genome stability and DNA integrity maintenance. The cellular response to DNA damage mainly consists of six biological conserved pathways known as homologous recombination repair (HRR), non-homologous end-joining (NHEJ), base excision repair (BER), mismatch repair (MMR), nucleotide excision repair (NER), and methyltransferase repair that operate in a concerted way to minimize genetic information loss due to a DNA lesion. Particularly, protozoan parasites survival depends on DNA repair mechanisms that constantly supervise chromosomes to correct damaged nucleotides generated by cytotoxic agents, host immune pressure or cellular processes. Here we reviewed the current knowledge about DNA repair mechanisms in the most relevant human protozoan pathogens. Additionally, we described the recent advances to understand DNA repair mechanisms in Entamoeba histolytica with special emphasis in the use of genomic approaches based on bioinformatic analysis of parasite genome sequence and microarrays technology.

  20. Mechanical engineers' handbook, design, instrumentation, and controls

    CERN Document Server

    Kutz, Myer

    2015-01-01

    Full coverage of electronics, MEMS, and instrumentation andcontrol in mechanical engineering This second volume of Mechanical Engineers' Handbookcovers electronics, MEMS, and instrumentation and control, givingyou accessible and in-depth access to the topics you'll encounterin the discipline: computer-aided design, product design formanufacturing and assembly, design optimization, total qualitymanagement in mechanical system design, reliability in themechanical design process for sustainability, life-cycle design,design for remanufacturing processes, signal processing, dataacquisition and dis

  1. Effects of mechanical loading on human mesenchymal stem cells for cartilage tissue engineering.

    Science.gov (United States)

    Choi, Jane Ru; Yong, Kar Wey; Choi, Jean Yu

    2017-05-19

    Today, articular cartilage damage is a major health problem, affecting people of all ages. The existing conventional articular cartilage repair techniques, such as autologous chondrocyte implantation (ACI), microfracture, and mosaicplasty, have many shortcomings which negatively affect their clinical outcomes. Therefore, it is essential to develop an alternative and efficient articular repair technique that can address those shortcomings. Cartilage tissue engineering, which aims to create a tissue-engineered cartilage derived from human mesenchymal stem cells (MSCs), shows great promise for improving articular cartilage defect therapy. However, the use of tissue-engineered cartilage for the clinical therapy of articular cartilage defect still remains challenging. Despite the importance of mechanical loading to create a functional cartilage has been well demonstrated, the specific type of mechanical loading and its optimal loading regime is still under investigation. This review summarizes the most recent advances in the effects of mechanical loading on human MSCs. First, the existing conventional articular repair techniques and their shortcomings are highlighted. The important parameters for the evaluation of the tissue-engineered cartilage, including chondrogenic and hypertrophic differentiation of human MSCs are briefly discussed. The influence of mechanical loading on human MSCs is subsequently reviewed and the possible mechanotransduction signaling is highlighted. The development of non-hypertrophic chondrogenesis in response to the changing mechanical microenvironment will aid in the establishment of a tissue-engineered cartilage for efficient articular cartilage repair. © 2017 Wiley Periodicals, Inc.

  2. Solving real world problems with mechanical engineering

    CERN Document Server

    Shea, Therese

    2016-01-01

    Planes, trains, and automobiles-these are just some of the many achievements of mechanical engineering. This volume will show readers that they do not have to know complex equations to appreciate the impact the field has had on the world. Accessible text introduces young readers to the machines and engines that power the devices, vehicles, and appliances they encounter on a daily basis. Boxes explain important terms and concepts of mechanics and encourage readers to think critically. The book ends with a guided activity that invites readers to don the hat of a mechanical engineer and build the

  3. The characteristics of mechanical engineering systems

    CERN Document Server

    Holmes, R

    1977-01-01

    The Characteristics of Mechanical Engineering Systems focuses on the characteristics that must be considered when designing a mechanical engineering system. Mechanical systems are presented on the basis of component input-output relationships, paying particular attention to lumped-parameter problems and the interrelationships between lumped components or """"black-boxes"""" in an engineering system. Electric motors and generators are treated in an elementary manner, and the principles involved are explained as far as possible from physical and qualitative reasoning. This book is comprised of

  4. Activities of the Institute for Mechanical Engineering

    Science.gov (United States)

    The Institute of Mechanical Engineering (IME) is part of Canada's National Research Council. Its mission is to undertake, support, promote, and disseminate research and development in the mechanical engineering aspects of three vital sectors of the Canadian economy: transportation, resource industries, and manufacturing. The IME achieves its mission by performing research and development in its own facilities; by developing, providing, and transferring expertise and knowledge; by making its research facilities available to collaborators and clients; and by participating in international liaison and collaborative research activities. Six research programs are conducted in the IME: Advanced Manufacturing Technology; Coastal Zone Engineering; Cold Regions Engineering; Combustion and Fluids Engineering; Ground Transportation Technology; and Machinery and Engine Technology. The rationale and major research thrusts of each program are described, and specific achievements in 1991-92 are reviewed. Lists of technical reports and papers presented by IME personnel are also included.

  5. Engineering Change Management Method Framework in Mechanical Engineering

    Science.gov (United States)

    Stekolschik, Alexander

    2016-11-01

    Engineering changes make an impact on different process chains in and outside the company, and lead to most error costs and time shifts. In fact, 30 to 50 per cent of development costs result from technical changes. Controlling engineering change processes can help us to avoid errors and risks, and contribute to cost optimization and a shorter time to market. This paper presents a method framework for controlling engineering changes at mechanical engineering companies. The developed classification of engineering changes and accordingly process requirements build the basis for the method framework. The developed method framework comprises two main areas: special data objects managed in different engineering IT tools and process framework. Objects from both areas are building blocks that can be selected to the overall business process based on the engineering process type and change classification. The process framework contains steps for the creation of change objects (both for overall change and for parts), change implementation, and release. Companies can select singleprocess building blocks from the framework, depending on the product development process and change impact. The developed change framework has been implemented at a division (10,000 employees) of a big German mechanical engineering company.

  6. Review: Modeling Damping in Mechanical Engineering Structures

    Directory of Open Access Journals (Sweden)

    Michel Lalanne

    2000-01-01

    Full Text Available This paper is concerned with the introduction of damping effects in the analysis of mechanical engineering structures. Damping can be considered as being generated by concentrated elements, by distributed elements, or by several effects existing simultaneously. Modeling damping for different engineering situations is described and some applications are presented briefly.

  7. Tissue-engineered tendon constructs for rotator cuff repair in sheep.

    Science.gov (United States)

    Novakova, Stoyna S; Mahalingam, Vasudevan D; Florida, Shelby E; Mendias, Christopher L; Allen, Answorth; Arruda, Ellen M; Bedi, Asheesh; Larkin, Lisa M

    2017-06-28

    Current rotator cuff repair commonly involves the use of single or double row suture techniques, and despite successful outcomes, failure rates continue to range from 20 to 95%. Failure to regenerate native biomechanical properties at the enthesis is thought to contribute to failure rates. Thus, the need for technologies that improve structural healing of the enthesis after rotator cuff repair is imperative. To address this issue, our lab has previously demonstrated enthesis regeneration using a tissue-engineered graft approach in a sheep anterior cruciate ligament (ACL) repair model. We hypothesized that our tissue-engineered graft designed for ACL repair also will be effective in rotator cuff repair. The goal of this study was to test the efficacy of our Engineered Tissue Graft for Rotator Cuff (ETG-RC) in a rotator cuff tear model in sheep and compare this novel graft technology to the commonly used double row suture repair technique. Following a 6-month recovery, the grafted and contralateral shoulders were removed, imaged using X-ray, and tested biomechanically. Additionally, the infraspinatus muscle, myotendinous junction, enthesis, and humeral head were preserved for histological analysis of muscle, tendon, and enthesis structure. Our results showed that our ETC-RCs reached 31% of the native tendon tangent modulus, which was a modest, non-significant, 11% increase over that of the suture-only repairs. However, the histological analysis showed the regeneration of a native-like enthesis in the ETG-RC-repaired animals. This advanced structural healing may improve over longer times and may diminish recurrence rates of rotator cuff tears and lead to better clinical outcomes. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

  8. Routine Design for Mechanical Engineering

    OpenAIRE

    Brinkop, Axel; Laudwein, Norbert; Maasen, Rudiger

    1995-01-01

    COMIX (configuration of mixing machines) is a system that assists members of the EKATO Sales Department in designing a mixing machine that fulfills the requirements of a customer. It is used to help the engineer design the requested machine and prepare an offer that's to be submitted to the customer. comix integrates more traditional software techniques with explicit knowledge representation and constraint propagation. During the process of routine design, some design decisions have to be mad...

  9. Fragile DNA Repair Mechanism Reduces Ageing in Multicellular Model

    DEFF Research Database (Denmark)

    Bendtsen, Kristian Moss; Juul, Jeppe Søgaard; Trusina, Ala

    2012-01-01

    DNA damages, as well as mutations, increase with age. It is believed that these result from increased genotoxic stress and decreased capacity for DNA repair. The two causes are not independent, DNA damage can, for example, through mutations, compromise the capacity for DNA repair, which in turn...... to DNA damage can undergo full repair, go apoptotic, or accumulate mutations thus reducing DNA repair capacity. Our model predicts that at the tissue level repair rate does not continuously decline with age, but instead has a characteristic extended period of high and non-declining DNA repair capacity...... of compromised cells, thus freeing the space for healthy peers. This finding might be a first step toward understanding why a mutation in single DNA repair protein (e.g. Wrn or Blm) is not buffered by other repair proteins and therefore, leads to severe ageing disorders...

  10. Fundamental Research in Engineering Education. Identifying and Repairing Student Misconceptions in Thermal and Transport Science: Concept Inventories and Schema Training Studies

    Science.gov (United States)

    Miller, Ronald L.; Streveler, Ruth A.; Yang, Dazhi; Roman, Aidsa I. Santiago

    2011-01-01

    This paper summarizes progress on two related lines of chemical engineering education research: 1) identifying persistent student misconceptions in thermal and transport science (fluid mechanics, heat transfer, and thermodynamics); and, 2) developing a method to help students repair these misconceptions. Progress on developing the Thermal and…

  11. Fundamental Research in Engineering Education. Identifying and Repairing Student Misconceptions in Thermal and Transport Science: Concept Inventories and Schema Training Studies

    Science.gov (United States)

    Miller, Ronald L.; Streveler, Ruth A.; Yang, Dazhi; Roman, Aidsa I. Santiago

    2011-01-01

    This paper summarizes progress on two related lines of chemical engineering education research: 1) identifying persistent student misconceptions in thermal and transport science (fluid mechanics, heat transfer, and thermodynamics); and, 2) developing a method to help students repair these misconceptions. Progress on developing the Thermal and…

  12. Mechanism of DNA loading by the DNA repair helicase XPD.

    Science.gov (United States)

    Constantinescu-Aruxandei, Diana; Petrovic-Stojanovska, Biljana; Penedo, J Carlos; White, Malcolm F; Naismith, James H

    2016-04-07

    The xeroderma pigmentosum group D (XPD) helicase is a component of the transcription factor IIH complex in eukaryotes and plays an essential role in DNA repair in the nucleotide excision repair pathway. XPD is a 5' to 3' helicase with an essential iron-sulfur cluster. Structural and biochemical studies of the monomeric archaeal XPD homologues have aided a mechanistic understanding of this important class of helicase, but several important questions remain open. In particular, the mechanism for DNA loading, which is assumed to require large protein conformational change, is not fully understood. Here, DNA binding by the archaeal XPD helicase from Thermoplasma acidophilum has been investigated using a combination of crystallography, cross-linking, modified substrates and biochemical assays. The data are consistent with an initial tight binding of ssDNA to helicase domain 2, followed by transient opening of the interface between the Arch and 4FeS domains, allowing access to a second binding site on helicase domain 1 that directs DNA through the pore. A crystal structure of XPD from Sulfolobus acidocaldiarius that lacks helicase domain 2 has an otherwise unperturbed structure, emphasizing the stability of the interface between the Arch and 4FeS domains in XPD.

  13. Mechanism of DNA loading by the DNA repair helicase XPD

    Science.gov (United States)

    Constantinescu-Aruxandei, Diana; Petrovic-Stojanovska, Biljana; Penedo, J. Carlos; White, Malcolm F.; Naismith, James H.

    2016-01-01

    The xeroderma pigmentosum group D (XPD) helicase is a component of the transcription factor IIH complex in eukaryotes and plays an essential role in DNA repair in the nucleotide excision repair pathway. XPD is a 5′ to 3′ helicase with an essential iron–sulfur cluster. Structural and biochemical studies of the monomeric archaeal XPD homologues have aided a mechanistic understanding of this important class of helicase, but several important questions remain open. In particular, the mechanism for DNA loading, which is assumed to require large protein conformational change, is not fully understood. Here, DNA binding by the archaeal XPD helicase from Thermoplasma acidophilum has been investigated using a combination of crystallography, cross-linking, modified substrates and biochemical assays. The data are consistent with an initial tight binding of ssDNA to helicase domain 2, followed by transient opening of the interface between the Arch and 4FeS domains, allowing access to a second binding site on helicase domain 1 that directs DNA through the pore. A crystal structure of XPD from Sulfolobus acidocaldiarius that lacks helicase domain 2 has an otherwise unperturbed structure, emphasizing the stability of the interface between the Arch and 4FeS domains in XPD. PMID:26896802

  14. Process-induced extracellular matrix alterations affect the mechanisms of soft tissue repair and regeneration

    Directory of Open Access Journals (Sweden)

    Wendell Q Sun

    2013-09-01

    Full Text Available Extracellular matrices derived from animal tissues for human tissue repairs are processed by various methods of physical, chemical, or enzymatic decellularization, viral inactivation, and terminal sterilization. The mechanisms of action in tissue repair vary among bioscaffolds and are suggested to be associated with process-induced extracellular matrix modifications. We compared three non-cross-linked, commercially available extracellular matrix scaffolds (Strattice, Veritas, and XenMatrix, and correlated extracellular matrix alterations to in vivo biological responses upon implantation in non-human primates. Structural evaluation showed significant differences in retaining native tissue extracellular matrix histology and ultrastructural features among bioscaffolds. Tissue processing may cause both the condensation of collagen fibers and fragmentation or separation of collagen bundles. Calorimetric analysis showed significant differences in the stability of bioscaffolds. The intrinsic denaturation temperature was measured to be 51°C, 38°C, and 44°C for Strattice, Veritas, and XenMatrix, respectively, demonstrating more extracellular matrix modifications in the Veritas and XenMatrix scaffolds. Consequently, the susceptibility to collagenase degradation was increased in Veritas and XenMatrix when compared to their respective source tissues. Using a non-human primate model, three bioscaffolds were found to elicit different biological responses, have distinct mechanisms of action, and yield various outcomes of tissue repair. Strattice permitted cell repopulation and was remodeled over 6 months. Veritas was unstable at body temperature, resulting in rapid absorption with moderate inflammation. XenMatrix caused severe inflammation and sustained immune reactions. This study demonstrates that extracellular matrix alterations significantly affect biological responses in soft tissue repair and regeneration. The data offer useful insights into the

  15. Tissue Engineering for Rotator Cuff Repair: An Evidence-Based Systematic Review

    Directory of Open Access Journals (Sweden)

    Nicola Maffulli

    2012-01-01

    Full Text Available The purpose of this systematic review was to address the treatment of rotator cuff tears by applying tissue engineering approaches to improve tendon healing, specifically platelet rich plasma (PRP augmentation, stem cells, and scaffolds. Our systematic search was performed using the combination of the following terms: “rotator cuff”, “shoulder”, “PRP”, “platelet rich plasma”, “stemcells”, “scaffold”, “growth factors”, and “tissue engineering”. No level I or II studies were found on the use of scaffolds and stem cells for rotator cuff repair. Three studies compared rotator cuff repair with or without PRP augmentation. All authors performed arthroscopic rotator cuff repair with different techniques of suture anchor fixation and different PRP augmentation. The three studies found no difference in clinical rating scales and functional outcomes between PRP and control groups. Only one study showed clinical statistically significant difference between the two groups at the 3-month followup. Any statistically significant difference in the rates of tendon rerupture between the control group and the PRP group was found using the magnetic resonance imaging. The current literature on tissue engineering application for rotator cuff repair is scanty. Comparative studies included in this review suggest that PRP augmented repair of a rotator cuff does not yield improved functional and clinical outcome compared with non-augmented repair at a medium and long-term followup.

  16. Mechanical engineers' handbook, energy and power

    CERN Document Server

    Kutz, Myer

    2015-01-01

    The engineer's ready reference for mechanical power and heat Mechanical Engineer's Handbook provides the mostcomprehensive coverage of the entire discipline, with a focus onexplanation and analysis. Packaged as a modular approach, thesebooks are designed to be used either individually or as a set,providing engineers with a thorough, detailed, ready reference ontopics that may fall outside their scope of expertise. Each bookprovides discussion and examples as opposed to straight data andcalculations, giving readers the immediate background they needwhile pointing them toward more in-depth infor

  17. Repairing articular cartilage defects with tissue-engineering cartilage in rabbits

    Institute of Scientific and Technical Information of China (English)

    SONG Hong-xing; LI Fo-bao; SHEN Hui-liang; LIAO Wei-ming; LIU Miao; WANG Min; CAO Jun-ling

    2006-01-01

    Objective: To investigate the effect of cancellous bone matrix gelatin (BMG) engineered with allogeneic chondrocytes in repairing articular cartilage defects in rabbits.Methods: Chondrocytes were seeded onto three-dimensional cancellous BMG and cultured in vitro for 12 days to prepare BMG-chondrocyte complexes. Under anesthesia with 2.5% pentobarbital sodium (1 ml/kg body weight), articular cartilage defects were made on the right knee joints of 38 healthy New Zealand white rabbits (regardless of sex, aged 4-5 months and weighing 2.5-3 kg) and the defects were then treated with 2.5 % trypsin.Then BMG-chondrocyte complex (Group A, n=18 ),BMG ( Group B, n=10), and nothing ( Group C, n=10)were implanted into the cartilage defects, respectively. The repairing effects were assessed by macroscopic, histologic,transmission electron microscopic (TEM) observation,immunohistochemical examination and in situ hybridization detection, respectively, at 2, 4, 8, 12 and 24 weeks after operation.Results: Cancellous BMG was degraded within 8 weeks after operation. In Group A, lymphocyte infiltration was observed around the graft. At 24 weeks after operation, the cartilage defects were repaired by cartilage tissues and the articular cartilage and subchondral bone were soundly healed. Proteoglycan and type Ⅱ collagen were detected in the matrix of the repaired tissues by Safranin-O staining and immunohistochemical staining,respectively. In situ hybridization proved gene expression of type Ⅱ collagen in the cytoplasm of chondrocytes in the repaired tissues. TEM observation showed that chondrocytes and cartilage matrix in repaired tissues were almost same as those in the normal articular cartilage. In Group B, the defects were repaired by cartilage-fibrous tissues. In Group C, the defects were repaired only by fibrous tissues.Conclusions : Cancellous BMG can be regarded as the natural cell scaffolds for cartilage tissue engineering.Articular cartilage defects can be repaired by

  18. Tissue engineered devices for ligament repair, replacement and ...

    African Journals Online (AJOL)

    PRECIOUS

    2009-12-29

    Dec 29, 2009 ... School of Biomedical Engineering and Sciences, Virginia Tech, Blacksburg, VA, USA, 24060. E-mail: ...... humans. Immunology Today, 14: 3. ... 558-570. Phelps CJ, Koike C, Vaught TD, Boone J, Wells KD, Chen SH, Ball S,.

  19. Lubrication System 2. Service the Crankcase Breather. Student Manual. Small Engine Repair Series. First Edition.

    Science.gov (United States)

    Hill, Pamela

    This student manual on servicing the crankcase breather is the third of three in an instructional package on the lubrication system in the Small Engine Repair Series for handicapped students. The stated purpose for the booklet is to help students learn what tools and equipment to use and all the steps of the job. Informative material and…

  20. Lubrication System. Introduction: Things for You to Know. Student Manual. Small Engine Repair Series. First Edition.

    Science.gov (United States)

    Hill, Pamela

    This student manual introducing the lubrication system is the first of three in an instructional package on the lubrication system in the Small Engine Repair Series for handicapped students. The stated purpose of the booklet is to help students learn about the lubrication system and safe and good work habits. Informative material and diagrams are…

  1. SIGNAL FLOW GRAPH ANALYSIS OF MECHANICAL ENGINEERING SYSTEMS

    Science.gov (United States)

    CONTROL SYSTEMS, *MECHANICS, *STRUCTURES, *THERMODYNAMICS, *TOPOLOGY, BEAMS(ELECTROMAGNETIC), BEAMS(STRUCTURAL), GAS FLOW, GEARS, HEAT EXCHANGERS, MATHEMATICAL ANALYSIS, MATHEMATICS, MECHANICAL ENGINEERING , RAMJET ENGINES.

  2. Mechanical technology for higher engineering technicians

    CERN Document Server

    Black, Peter

    1972-01-01

    Mechanical Technology for Higher Engineering Technicians deals with the mechanics of machines, thermodynamics, and mechanics of fluids. This book presents discussions and examples that deal with the strength of materials, technology of machines, and techniques used by professional engineers. The book explains the strain energy of torsion, coil springs, and the effects of axial load. The author also discusses the forces that produce bending, shearing, and bending combined with direct stress, as well as beams subjected to a uniform bending moment or simply supported beams with concentrated non-c

  3. Optimization of a relativistic quantum mechanical engine

    Science.gov (United States)

    Peña, Francisco J.; Ferré, Michel; Orellana, P. A.; Rojas, René G.; Vargas, P.

    2016-08-01

    We present an optimal analysis for a quantum mechanical engine working between two energy baths within the framework of relativistic quantum mechanics, adopting a first-order correction. This quantum mechanical engine, with the direct energy leakage between the energy baths, consists of two adiabatic and two isoenergetic processes and uses a three-level system of two noninteracting fermions as its working substance. Assuming that the potential wall moves at a finite speed, we derive the expression of power output and, in particular, reproduce the expression for the efficiency at maximum power.

  4. Computational structural mechanics for engine structures

    Science.gov (United States)

    Chamis, C. C.

    1989-01-01

    The computational structural mechanics (CSM) program at Lewis encompasses: (1) fundamental aspects for formulating and solving structural mechanics problems, and (2) development of integrated software systems to computationally simulate the performance/durability/life of engine structures. It is structured to mainly supplement, complement, and whenever possible replace, costly experimental efforts which are unavoidable during engineering research and development programs. Specific objectives include: investigate unique advantages of parallel and multiprocesses for: reformulating/solving structural mechanics and formulating/solving multidisciplinary mechanics and develop integrated structural system computational simulators for: predicting structural performances, evaluating newly developed methods, and for identifying and prioritizing improved/missing methods needed. Herein the CSM program is summarized with emphasis on the Engine Structures Computational Simulator (ESCS). Typical results obtained using ESCS are described to illustrate its versatility.

  5. Surgical repair of chronic tears of the hip abductor mechanism.

    Science.gov (United States)

    Davies, Hywel; Zhaeentan, Sohelia; Tavakkolizadeh, Adel; Janes, Gregory

    2009-01-01

    Lateral sided hip pain frequently presents to the orthopaedic clinic. The most common cause of this pain is trochanteric bursitis. This usually improves with conservative treatment. In a few cases it doesn't settle and warrants further investigation and treatment. We present a series of 28 patients who underwent MRI scanning for such pain, 16 were found to have a tear of their abductors. All 16 underwent surgical repair using multiple soft tissue anchors inserted into the greater trochanter of the hip to reattach the abductors. There were 15 females and 1 male. All patients completed a self-administered questionnaire pre-operatively and 1 year post-operatively. Data collected included: A visual analogue score for hip pain, Charnley modification of the Merle D'Aubigne and Postel hip score, Oxford hip score, Kuhfuss score of Trendelenburg and SF36 scores.Of the 16 patients who underwent surgery 5 had a failure of surgical treatment. There were 4 re ruptures, 3 of which were revised and 1 deep infection which required debridement. In the remaining 11 patients there were statistically significant improvements in hip symptoms. The mean change in visual analogue score was 5 out of 10 (p=0.0024) The mean change of Oxford hip score was 20.5 (p=0.00085). The mean improvement in SF-36 PCS was 8.5 (P=0.0020) and MCS 13.7 (P=0.134). 6 patients who had a Trendelenburg gait pre-surgery had normal gait 1 year following surgery.We conclude that hip abductor mechanism tear is a frequent cause of recalcitrant trochanteric pain that should be further investigated with MRI scanning. Surgical repair is a successful operation for reduction of pain and improvement of function. However there is a relatively high failure rate.

  6. Mechanical engineers' handbook, manufacturing and management

    CERN Document Server

    Kutz, Myer

    2015-01-01

    Full coverage of manufacturing and management in mechanicalengineering Mechanical Engineers' Handbook, Fourth Edition provides aquick guide to specialized areas that engineers may encounter intheir work, providing access to the basics of each and pointingtoward trusted resources for further reading, if needed. The book'saccessible information offers discussions, examples, and analysesof the topics covered, rather than the straight data, formulas, andcalculations found in other handbooks. No single engineer can be aspecialist in all areas that they are called upon to work in. It'sa discipline

  7. 46 CFR 12.15-13 - Deck engine mechanic.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Deck engine mechanic. 12.15-13 Section 12.15-13 Shipping... ENDORSEMENTS Qualified Member of the Engine Department § 12.15-13 Deck engine mechanic. (a) An applicant for an endorsement as deck engine mechanic shall be a person holding an MMC or MMD endorsed as junior engineer....

  8. Interplay between mechanisms of damage and repair in multiple sclerosis.

    Science.gov (United States)

    Stadelmann, Christine; Brück, Wolfgang

    2008-03-01

    The neuropathology of multiple sclerosis is characterised by focal damage to white matter. However, tissue damage is also present in the cortical grey matter, with a particularly high prevalence of cortical demyelination being observed in secondary progressive and primary progressive forms of the disease. The presence of meningeal B-cell follicle-like structures, which frequently appear during the secondary progressive phase of disease, may be involved in the formation of these subpial cortical lesions. Diffuse white matter inflammation accompanied by axonal damage can also be observed in normal appearing white matter and, again, this is more prominent in chronic progressive forms of multiple sclerosis than in acute stages of disease. Axonal damage is a particularly important component of the pathology of multiple sclerosis and appears to be a critical determinant of clinical outcome. Axons appear to become vulnerable to injury as a result of loss of their myelin sheaths. Remyelination represents an important mechanism of tissue repair in multiple sclerosis and already occurs at an early stage of lesion development and in both white and grey matter lesions. The extent of remyelination appears to be greater in cortical lesions and in lesions further from the ventricles. There is important heterogeneity between patients in terms of the extent of remyelination, which may reflect underlying differences in pathogenetic mechanisms between patients.

  9. Impact of occupational mechanical exposures on risk of lateral and medial inguinal hernia requiring surgical repair

    DEFF Research Database (Denmark)

    Vad, Marie Vestergaard; Frost, Poul; Bay-Nielsen, Morten;

    2012-01-01

    We undertook a register-based cohort study to evaluate exposure-response relations between cumulative occupational mechanical exposures, and risk of lateral and medial inguinal hernia repair.......We undertook a register-based cohort study to evaluate exposure-response relations between cumulative occupational mechanical exposures, and risk of lateral and medial inguinal hernia repair....

  10. Micro electromechanical systems (MEMS) for mechanical engineers

    Energy Technology Data Exchange (ETDEWEB)

    Lee, A. P., LLNL

    1996-11-18

    The ongoing advances in Microelectromechanical Systems (MEMS) are providing man-kind the freedom to travel to dimensional spaces never before conceivable. Advances include new fabrication processes, new materials, tailored modeling tools, new fabrication machines, systems integration, and more detailed studies of physics and surface chemistry as applied to the micro scale. In the ten years since its inauguration, MEMS technology is penetrating industries of automobile, healthcare, biotechnology, sports/entertainment, measurement systems, data storage, photonics/optics, computer, aerospace, precision instruments/robotics, and environment monitoring. It is projected that by the turn of the century, MEMS will impact every individual in the industrial world, totaling sales up to $14 billion (source: System Planning Corp.). MEMS programs in major universities have spawned up all over the United States, preparing the brain-power and expertise for the next wave of MEMS breakthroughs. It should be pointed out that although MEMS has been initiated by electrical engineering researchers through the involvement of IC fabrication techniques, today it has evolved such that it requires a totally multi-disciplinary team to develop useful devices. Mechanical engineers are especially crucial to the success of MEMS development, since 90% of the physical realm involved is mechanical. Mechanical engineers are needed for the design of MEMS, the analysis of the mechanical system, the design of testing apparatus, the implementation of analytical tools, and the packaging process. Every single aspect of mechanical engineering is being utilized in the MEMS field today, however, the impact could be more substantial if more mechanical engineers are involved in the systems level designing. In this paper, an attempt is made to create the pathways for a mechanical engineer to enter in the MEMS field. Examples of application in optics and medical devices will be used to illustrate how mechanical

  11. International Conference on Mechanical Engineering and Technology

    CERN Document Server

    Mechanical Engineering and Technology

    2012-01-01

    The volume includes a set of selected papers extended and revised from the 2011 International Conference on Mechanical Engineering and Technology, held on London, UK, November 24-25, 2011.   Mechanical engineering technology is the application of physical principles and current technological developments to the creation of useful machinery and operation design. Technologies such as solid models may be used as the basis for finite element analysis (FEA) and / or computational fluid dynamics (CFD) of the design. Through the application of computer-aided manufacturing (CAM), the models may also be used directly by software to create "instructions" for the manufacture of objects represented by the models, through computer numerically controlled (CNC) machining or other automated processes, without the need for intermediate drawings.   This volume covers the subject areas of mechanical engineering and technology, and also covers interdisciplinary subject areas of computers, communications, control and automation...

  12. Mechanical engineering capstone senior design textbook

    Science.gov (United States)

    Barrett, Rolin Farrar, Jr.

    This textbook is intended to bridge the gap between mechanical engineering equations and mechanical engineering design. To that end, real-world examples are used throughout the book. Also, the material is presented in an order that follows the chronological sequence of coursework that must be performed by a student in the typical capstone senior design course in mechanical engineering. In the process of writing this book, the author surveyed the fifty largest engineering schools (as ranked by the American Society of Engineering Education, or ASEE) to determine what engineering instructors are looking for in a textbook. The survey results revealed a clear need for a textbook written expressly for the capstone senior design course as taught throughout the nation. This book is designed to meet that need. This text was written using an organizational method that the author calls the General Topics Format. The format gives the student reader rapid access to the information contained in the text. All manufacturing methods, and some other material presented in this text, have been presented using the General Topics Format. The text uses examples to explain the importance of understanding the environment in which the product will be used and to discuss product abuse. The safety content contained in this text is unique. The Safety chapter teaches engineering ethics and includes a step-by-step guide to resolving ethical conflicts. The chapter includes explanations of rules, recommendations, standards, consensus standards, key safety concepts, and the legal implications of product failure. Key design principles have been listed and explained. The text provides easy-to-follow design steps, helpful for both the student and new engineer. Prototyping is presented as consisting of three phases: organization, building, and refining. A chapter on common manufacturing methods is included for reference.

  13. Mechanics, Models and Methods in Civil Engineering

    CERN Document Server

    Maceri, Franco

    2012-01-01

    Mechanics, Models and Methods in Civil Engineering” collects leading papers dealing with actual Civil Engineering problems. The approach is in the line of the Italian-French school and therefore deeply couples mechanics and mathematics creating new predictive theories, enhancing clarity in understanding, and improving effectiveness in applications. The authors of the contributions collected here belong to the Lagrange Laboratory, an European Research Network active since many years. This book will be of a major interest for the reader aware of modern Civil Engineering.

  14. Elements of theoretical mechanics for electronic engineers

    CERN Document Server

    Bultot, Franz

    1965-01-01

    Elements of Theoretical Mechanics for Electronic Engineers deals with theoretical mechanics, which is considered one of the fundamental branches of instruction essential to training an engineer. This book discusses the oscillatory motions and their counterparts in electrical circuits and radio, and provides an introduction to differential operators of vector field theory. Other topics covered include systems and functions of vectors; dynamics of a free point; vibrations and waves; and statics. Worked examples and many notes on the application of most sections of the theories to electrical deve

  15. Mechanism and Durability of Repair Systems in Polymer-Modified Cement Mortars

    Directory of Open Access Journals (Sweden)

    Ru Wang

    2015-01-01

    Full Text Available This paper investigated the mechanism and durability of repair systems made of ordinary cement-based repair mortar and three kinds of polymer-modified repair mortars with old concrete, SBR dispersion, SAE dispersion, and SAE powder. By comparing the bonding properties of mortars before and after erosion, it was found that polymers could effectively improve the durability of the repair system and SAE powder had the best improvement. Micromorphology study of the repair mortar and the interface of repair mortar with old concrete through SEM showed that the polymer film formed from SAE powder whatever in the mortar or at the interface was dense and tough, the film formed from SAE dispersion was loose and weak, while the film formed from SBR dispersion was in between them, which explained the difference in the tensile bond strength and the durability of the repair systems.

  16. Control of gene editing by manipulation of DNA repair mechanisms.

    Science.gov (United States)

    Danner, Eric; Bashir, Sanum; Yumlu, Saniye; Wurst, Wolfgang; Wefers, Benedikt; Kühn, Ralf

    2017-04-03

    DNA double-strand breaks (DSBs) are produced intentionally by RNA-guided nucleases to achieve genome editing through DSB repair. These breaks are repaired by one of two main repair pathways, classic non-homologous end joining (c-NHEJ) and homology-directed repair (HDR), the latter being restricted to the S/G2 phases of the cell cycle and notably less frequent. Precise genome editing applications rely on HDR, with the abundant c-NHEJ formed mutations presenting a barrier to achieving high rates of precise sequence modifications. Here, we give an overview of HDR- and c-NHEJ-mediated DSB repair in gene editing and summarize the current efforts to promote HDR over c-NHEJ.

  17. Mechanics of materials formulas and problems : engineering mechanics 2

    CERN Document Server

    Gross, Dietmar; Wriggers, Peter; Schröder, Jörg; Müller, Ralf

    2017-01-01

    This book contains the most important formulas and more than 140 completely solved problems from Mechanics of Materials and Hydrostatics. It provides engineering students material to improve their skills and helps to gain experience in solving engineering problems. Particular emphasis is placed on finding the solution path and formulating the basic equations. Topics include: - Stress - Strain - Hooke’s Law - Tension and Compression in Bars - Bending of Beams - Torsion - Energy Methods - Buckling of Bars - Hydrostatics .

  18. Effects of scuba diving on vascular repair mechanisms.

    Science.gov (United States)

    Culic, Vedrana Cikes; Van Craenenbroeck, Emeline; Muzinic, Nikolina Rezic; Ljubkovic, Marko; Marinovic, Jasna; Conraads, Viviane; Dujic, Zeljko

    2014-01-01

    A single air dive causes transient endothelial dysfunction. Endothelial progenitor cells (EPCs) and circulating angiogenic cells (CAC) contribute synergistically to endothelial repair. In this study (1) the acute effects of diving on EPC numbers and CAC migration and (2) the influence of the gas mixture (air/nitrox-36) was investigated. Ten divers performed two dives to 18 meters on Day (D) 1 and D3, using air. After 15 days, dives were repeated with nitrox-36. Blood sampling took place before and immediately after diving. Circulating EPCs were quantified by flow cytometry, CAC migration of culture was assessed on D7. When diving on air, a trend for reduced EPC numbers is observed post-dive, which is persistent on D1 and D3. CAC migration tends to improve acutely following diving. These effects are more pronounced with nitrox-36 dives. Diving acutely affects EPC numbers and CAC function, and to a larger extent when diving with nitrox-36. The diving-induced oxidative stress may influence recruitment or survival of EPC. The functional improvement of CAC could be a compensatory mechanism to maintain endothelial homeostasis.

  19. Thermal integrity in mechanics and engineering

    CERN Document Server

    Shorr, Boris F

    2015-01-01

    The book is targeted at engineers, university lecturers, postgraduates, and final year undergraduate students involved in computational modelling and experimental and theoretical analysis of the high-temperature behavior of engineering structures. It will also be of interest to researchers developing the thermal strength theory as a branch of continuum mechanics. Thermal integrity is a multidisciplinary field combining the expertise of mechanical engineers, material scientists and applied mathematicians, each approaching the problem from their specific viewpoint. This monograph draws on the research of a broad scientific community including the author’s contribution. The scope of thermal strength analysis was considerably extended thanks to modern computers and the implementation of FEM codes. However, the author believes that some material models adopted in the advanced high-performance software, are not sufficiently justificated due to lack of easy-to-follow books on the theoretical and experimental aspec...

  20. Structural engineering, mechanics and materials: Final report

    Energy Technology Data Exchange (ETDEWEB)

    1988-01-01

    This report on structural engineering, mechanics and materials is divided into three parts: a discussion on using Lanczos vectors and Ritz vectors for computing dynamic responses: solution of viscously damped linear systems using a finite element displacement formulation; and vibration analysis of fluid-solid systems using a finite element displacement formulation. (JF)

  1. Gasoline Engine Mechanics. Performance Objectives. Intermediate Course.

    Science.gov (United States)

    Jones, Marion

    Several intermediate performance objectives and corresponding criterion measures are listed for each of six terminal objectives presented in this curriculum guide for an intermediate gasoline engine mechanics course at the secondary level. (For the beginning course guide see CE 010 947.) The materials were developed for a two-semester (2 hour…

  2. DESIGN QUALITY IN MECHANICAL ENGINEERING APPLICATION

    Directory of Open Access Journals (Sweden)

    Ayşegül Akdogan Eker

    2010-09-01

    Full Text Available There is a close relationship between material chose and quality in mechanical engineering application like there is in all the other engineering applications. If this relation is balanced then engineering success increases. Material chose comes to fore in the design process most of the time. The two most important responsibilities of the design engineer in here is to chose suitable material and to know the production processes about design. The chose of material of a design that will fulfill the needs all through its life has great importance. It is needed to limit the material applicants by choosing the most suitable ones among variable material. Choosing materials that were examined before and whose behavior is well known provides the designer to feel confident. However since using highly successful materials would increase the competitive power of the designs; designers should follow the developments in materials and know the features of new materials. The description of these features can be interpreted within quality. Quality from the point of engineer is the total fulfillment of expectations.Engineer today are faced with very important problems such as fast technological innovations, a dynamic socio-economical environment, global rivalry. One of the life buoys they stick while trying to solve these problems is total method of quality control. Total Quality model which can provide higher competitive power compared to classical management model brings success only when applied with its whole components. "Approach toward prevention" and "measurement and statistics" have an important place among these elements. The first step of the approach toward prevention composes of design quality and Quality Function Deployment (QFD, or in other words The House of Quality method that will provide this. In this paper; considering the quality function deployment, how the chose of material are done in mechanical engineering applications will be explained.

  3. Detection of abnormalities in the superficial zone of cartilage repaired using a tissue engineered construct derived from synovial stem cells.

    Science.gov (United States)

    Ando, Wataru; Fujie, Hiromichi; Moriguchi, Yu; Nansai, Ryosuke; Shimomura, Kazunori; Hart, David A; Yoshikawa, Hideki; Nakamura, Norimasa

    2012-09-28

    The present study investigated the surface structure and mechanical properties of repair cartilage generated from a tissue engineered construct (TEC) derived from synovial mesenchymal stem cells at six months post-implantation compared to those of uninjured cartilage. TEC-mediated repair tissue was cartilaginous with Safranin O staining, and had comparable macro-scale compressive properties with uninjured cartilage. However, morphological assessments revealed that the superficial zone of TEC-mediated tissue was more fibrocartilage-like, in contrast to the middle or deep zones that were more hyaline cartilage-like with Safranin O staining. Histological scoring of the TEC-mediated tissue was significantly lower in the superficial zone than in the middle and deep zones. Scanning electron microscopy showed a thick tangential bundle of collagen fibres at the most superficial layer of uninjured cartilage, while no corresponding structure was detected at the surface of TEC-mediated tissue. Immunohistochemical analysis revealed that PRG4 was localised in the superficial area of uninjured cartilage, as well as the TEC-mediated tissue. Friction testing showed that the lubrication properties of the two tissues was similar, however, micro-indentation analysis revealed that the surface stiffness of the TEC-repair tissue was significantly lower than that of uninjured cartilage. Permeability testing indicated that the TEC-mediated tissue exhibited lower water retaining capacity than did uninjured cartilage, specifically at the superficial zone. Thus, TEC-mediated tissue exhibited compromised mechanical properties at the superficial zone, properties which need improvement in the future for maintenance of long term repair cartilage integrity.

  4. Detection of abnormalities in the superficial zone of cartilage repaired using a tissue engineered construct derived from synovial stem cells

    Directory of Open Access Journals (Sweden)

    W Ando

    2012-09-01

    Full Text Available The present study investigated the surface structure and mechanical properties of repair cartilage generated from a tissue engineered construct (TEC derived from synovial mesenchymal stem cells at six months post-implantation compared to those of uninjured cartilage. TEC-mediated repair tissue was cartilaginous with Safranin O staining, and had comparable macro-scale compressive properties with uninjured cartilage. However, morphological assessments revealed that the superficial zone of TEC-mediated tissue was more fibrocartilage-like, in contrast to the middle or deep zones that were more hyaline cartilage-like with Safranin O staining. Histological scoring of the TEC-mediated tissue was significantly lower in the superficial zone than in the middle and deep zones. Scanning electron microscopy showed a thick tangential bundle of collagen fibres at the most superficial layer of uninjured cartilage, while no corresponding structure was detected at the surface of TEC-mediated tissue. Immunohistochemical analysis revealed that PRG4 was localised in the superficial area of uninjured cartilage, as well as the TEC-mediated tissue. Friction testing showed that the lubrication properties of the two tissues was similar, however, micro-indentation analysis revealed that the surface stiffness of the TEC-repair tissue was significantly lower than that of uninjured cartilage. Permeability testing indicated that the TEC-mediated tissue exhibited lower water retaining capacity than did uninjured cartilage, specifically at the superficial zone. Thus, TEC-mediated tissue exhibited compromised mechanical properties at the superficial zone, properties which need improvement in the future for maintenance of long term repair cartilage integrity.

  5. Mathematical formulas for industrial and mechanical engineering

    CERN Document Server

    Kadry, Seifedine

    2014-01-01

    Mathematical Formulas For Industrial and Mechanical Engineering serves the needs of students and teachers as well as professional workers in engineering who use mathematics. The contents and size make it especially convenient and portable. The widespread availability and low price of scientific calculators have greatly reduced the need for many numerical tables that make most handbooks bulky. However, most calculators do not give integrals, derivatives, series and other mathematical formulas and figures that are often needed. Accordingly, this book contains that information in an easy way to

  6. Quantum mechanics for applied physics and engineering

    CERN Document Server

    Fromhold, Albert T

    2011-01-01

    This excellent text, directed to upper-level undergraduates and graduate students in engineering and applied physics, introduces the fundamentals of quantum mechanics, emphasizing those aspects of quantum mechanics and quantum statistics essential to an understanding of solid-state theory. A heavy background in mathematics and physics is not required beyond basic courses in calculus, differential equations, and calculus-based elementary physics.The first three chapters introduce quantum mechanics (using the Schrödinger equations), quantum statistics, and the free-electron theory of metals. Ch

  7. Service the Two-Piece Flo-Jet Carburetor. Fuel System. Student Manual 3. Small Engine Repair Series. First Edition.

    Science.gov (United States)

    Hill, Pamela

    This student manual, part of a small-engine repair series on servicing fuel systems, is designed for use by special needs students in Texas. The manual explains in pictures and short sentences, written on a low reading level, the job of servicing two-piece flo-jet carburetors. Along with the steps of this repair job, specific safety and caution…

  8. Human Cardiac Tissue Engineering: From Pluripotent Stem Cells to Heart Repair

    Science.gov (United States)

    Jackman, Christopher P.; Shadrin, Ilya Y.; Carlson, Aaron L.; Bursac, Nenad

    2014-01-01

    Engineered cardiac tissues hold great promise for use in drug and toxicology screening, in vitro studies of human physiology and disease, and as transplantable tissue grafts for myocardial repair. In this review, we discuss recent progress in cell-based therapy and functional tissue engineering using pluripotent stem cell-derived cardiomyocytes and we describe methods for delivery of cells into the injured heart. While significant hurdles remain, notable advances have been made in the methods to derive large numbers of pure human cardiomyocytes, mature their phenotype, and produce and implant functional cardiac tissues, bringing the field a step closer to widespread in vitro and in vivo applications. PMID:25599018

  9. Sternal Repair with Bone Grafts Engineered from Amniotic Mesenchymal Stem Cells

    Science.gov (United States)

    Steigman, Shaun A.; Ahmed, Azra; Shanti, Rabie M.; Tuan, Rocky S.; Valim, Clarissa; Fauza, Dario O.

    2013-01-01

    Background We aimed at determining whether osseous grafts engineered from amniotic mesenchymal stem cells (aMSCs) could be employed in postnatal sternal repair. Methods Leporine aMSCs were isolated, identified, transfected with green fluorescent protein (GFP), expanded, and seeded onto biodegradable electrospun nanofibrous scaffolds (n=6). Constructs were dynamically maintained in an osteogenic medium and equally divided into two groups with respect to time in vitro, namely 14.6 or 33.9 weeks. They were then used to repair full thickness sternal defects spanning 2–3 intercostal spaces in allogeneic kits (n=6). Grafts were submitted to multiple analyses 2 months thereafter. Results Chest roentgenograms showed defect closure in all animals, confirmed at necropsy. Graft density as assessed by micro-CT scans increased significantly in vivo, yet there were no differences in mineralization by extracellular calcium measurements pre- and post-implantation. There was a borderline increase in alkaline phosphatase activity in vivo, suggesting ongoing graft remodeling. Histologically, implants contained GFP-positive cells and few mononuclear infiltrates. There were no differences between the two construct groups in any comparison. Conclusions Engineered osseous grafts derived from amniotic mesenchymal stem cells may become a viable alternative for sternal repair. The amniotic fluid can be a practical cell source for engineered chest wall reconstruction. PMID:19524727

  10. The Impact of Hedgehog Signaling Pathway on DNA Repair Mechanisms in Human Cancer

    Directory of Open Access Journals (Sweden)

    Erhong Meng

    2015-07-01

    Full Text Available Defined cellular mechanisms have evolved that recognize and repair DNA to protect the integrity of its structure and sequence when encountering assaults from endogenous and exogenous sources. There are five major DNA repair pathways: mismatch repair, nucleotide excision repair, direct repair, base excision repair and DNA double strand break repair (including non-homologous end joining and homologous recombination repair. Aberrant activation of the Hedgehog (Hh signaling pathway is a feature of many cancer types. The Hh pathway has been documented to be indispensable for epithelial-mesenchymal transition, invasion and metastasis, cancer stemness, and chemoresistance. The functional transcription activators of the Hh pathway include the GLI proteins. Inhibition of the activity of GLI can interfere with almost all DNA repair types in human cancer, indicating that Hh/GLI functions may play an important role in enabling tumor cells to survive lethal types of DNA damage induced by chemotherapy and radiotherapy. Thus, Hh signaling presents an important therapeutic target to overcome DNA repair-enabled multi-drug resistance and consequently increase chemotherapeutic response in the treatment of cancer.

  11. The Impact of Hedgehog Signaling Pathway on DNA Repair Mechanisms in Human Cancer

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Erhong; Hanna, Ann; Samant, Rajeev S.; Shevde, Lalita A., E-mail: lsamant@uab.edu [Department of Pathology, Comprehensive Cancer Center, University of Alabama at Birmingham, WTI320D, 1824 6th Avenue South, Birmingham, AL 35233 (United States)

    2015-07-21

    Defined cellular mechanisms have evolved that recognize and repair DNA to protect the integrity of its structure and sequence when encountering assaults from endogenous and exogenous sources. There are five major DNA repair pathways: mismatch repair, nucleotide excision repair, direct repair, base excision repair and DNA double strand break repair (including non-homologous end joining and homologous recombination repair). Aberrant activation of the Hedgehog (Hh) signaling pathway is a feature of many cancer types. The Hh pathway has been documented to be indispensable for epithelial-mesenchymal transition, invasion and metastasis, cancer stemness, and chemoresistance. The functional transcription activators of the Hh pathway include the GLI proteins. Inhibition of the activity of GLI can interfere with almost all DNA repair types in human cancer, indicating that Hh/GLI functions may play an important role in enabling tumor cells to survive lethal types of DNA damage induced by chemotherapy and radiotherapy. Thus, Hh signaling presents an important therapeutic target to overcome DNA repair-enabled multi-drug resistance and consequently increase chemotherapeutic response in the treatment of cancer.

  12. Mechanical Engineering Department engineering research: Annual report, FY 1986

    Energy Technology Data Exchange (ETDEWEB)

    Denney, R.M.; Essary, K.L.; Genin, M.S.; Highstone, H.H.; Hymer, J.D.; Taft, S.O. (eds.)

    1986-12-01

    This report provides information on the five areas of research interest in LLNL's Mechanical Engineering Department. In Computer Code Development, a solid geometric modeling program is described. In Dynamic Systems and Control, structure control and structure dynamics are discussed. Fabrication technology involves machine cutting, interferometry, and automated optical component manufacturing. Materials engineering reports on composite material research and measurement of molten metal surface properties. In Nondestructive Evaluation, NMR, CAT, and ultrasound machines are applied to manufacturing processes. A model for underground collapse is developed. Finally, an alternative heat exchanger is investigated for use in a fusion power plant. Separate abstracts were prepared for each of the 13 reports in this publication. (JDH)

  13. Activity report of Mechanical Engineering Center

    Energy Technology Data Exchange (ETDEWEB)

    1997-07-01

    On April 1997, National Laboratory for High Energy Physics (KEK), Institute of Nuclear Study, University of Tokyo (INS), and Meson Science Laboratory; Faculty of Science, University of Tokyo began to work newly as High Energy Accelerator Research Organization after reconstructing and converting their systems, under aiming at further development of a wide field of accelerator science using a high energy accelerator. Hitherto, the large scale research plans of accelerator at the KEK have been not only received their relation communities on learning importance, meanings and social factors from their stages, but also promoted carefully under opinions and evaluation of outer objective ones and received outer serious evaluations for established research results either. Mechanical Engineering Center belonging to Applied Research Laboratory in the new Organization, started under jointing some sections relating to KEK and INS. As separately operating at the old organization engineering center in Tsukuba area and at engineering room in Tanashi Laboratory for some years, the Center was intended to integrate after 2000 to use this evaluation results for future development. This report was prepared separately on actions at the old engineering center of KEK as its first section and the engineering room of INS as its second section. (G.K.)

  14. Thermo-Mechanical Compatibility of Viscoelastic Mortars for Stone Repair

    Directory of Open Access Journals (Sweden)

    Thibault Demoulin

    2016-01-01

    Full Text Available The magnitude of the thermal stresses that originate in an acrylic-based repair material used for the reprofiling of natural sandstone is analyzed. This kind of artificial stone was developed in the late 1970s for its peculiar property of reversibility in an organic solvent. However, it displays a high thermal expansion coefficient, which can be a matter of concern for the durability either of the repair or of the underlying original stone. To evaluate this risk we propose an analytical solution that considers the viscoelasticity of the repair layer. The temperature profile used in the numerical evaluation has been measured in a church where artificial stone has been used in a recent restoration campaign. The viscoelasticity of the artificial stone has been characterized by stress relaxation experiments. The numerical analysis shows that the relaxation time of the repair mortar, originating from a low T g , allows relief of most of the thermal stresses. It explains the good durability of this particular repair material, as observed by the practitioners, and provides a solid scientific basis for considering that the problem of thermal expansion mismatch is not an issue for this type of stone under any possible conditions of natural exposure.

  15. Cell resistance to the Cytolethal Distending Toxin involves an association of DNA repair mechanisms

    Science.gov (United States)

    Bezine, Elisabeth; Malaisé, Yann; Loeuillet, Aurore; Chevalier, Marianne; Boutet-Robinet, Elisa; Salles, Bernard; Mirey, Gladys; Vignard, Julien

    2016-01-01

    The Cytolethal Distending Toxin (CDT), produced by many bacteria, has been associated with various diseases including cancer. CDT induces DNA double-strand breaks (DSBs), leading to cell death or mutagenesis if misrepaired. At low doses of CDT, other DNA lesions precede replication-dependent DSB formation, implying that non-DSB repair mechanisms may contribute to CDT cell resistance. To address this question, we developed a proliferation assay using human cell lines specifically depleted in each of the main DNA repair pathways. Here, we validate the involvement of the two major DSB repair mechanisms, Homologous Recombination and Non Homologous End Joining, in the management of CDT-induced lesions. We show that impairment of single-strand break repair (SSBR), but not nucleotide excision repair, sensitizes cells to CDT, and we explore the interplay of SSBR with the DSB repair mechanisms. Finally, we document the role of the replicative stress response and demonstrate the involvement of the Fanconi Anemia repair pathway in response to CDT. In conclusion, our work indicates that cellular survival to CDT-induced DNA damage involves different repair pathways, in particular SSBR. This reinforces a model where CDT-related genotoxicity primarily involves SSBs rather than DSBs, underlining the importance of cell proliferation during CDT intoxication and pathogenicity. PMID:27775089

  16. Tandem repeat modification during double-strand break repair induced by an engineered TAL effector nuclease in zebrafish genome.

    Directory of Open Access Journals (Sweden)

    Wanxu Huang

    Full Text Available Tandem repeats (TRs are abundant and widely distributed in eukaryotic genomes. TRs are thought to have various functions in gene transcription, DNA methylation, nucleosome position and chromatin organization. Variation of repeat units in the genome is observed in association with a number of diseases, such as Fragile X Syndrome, Huntington's disease and Friedreich's ataxia. However, the underlying mechanisms involved are poorly understood, largely owing to the technical limitations in modification of TRs at definite sites in the genome in vivo. Transcription activator-like effector nucleases (TALENs are widely used in recent years in gene targeting for their specific binding to target sequences when engineered in vitro. Here, we show that the repair of a double-strand break (DSB induced by TALENs adjacent to a TR can produce serial types of mutations in the TR region. Sequencing analysis revealed that there are three types of mutations induced by the DSB repair, including indels only within the TR region or within the flanking TALEN target region or simutaneously within both regions. Therefore, desired TR mutant types can be conveniently obtained by using engineered TALENs. These results demonstrate that TALENs can serve as a convenient tool for modifying TRs in the genome in studying the functions of TRs.

  17. Biomedical engineering strategies for peripheral nerve repair: surgical applications, state of the art, and future challenges.

    Science.gov (United States)

    Pfister, Bryan J; Gordon, Tessa; Loverde, Joseph R; Kochar, Arshneel S; Mackinnon, Susan E; Cullen, D Kacy

    2011-01-01

    Damage to the peripheral nervous system is surprisingly common and occurs primarily from trauma or a complication of surgery. Although recovery of nerve function occurs in many mild injuries, outcomes are often unsatisfactory following severe trauma. Nerve repair and regeneration presents unique clinical challenges and opportunities, and substantial contributions can be made through the informed application of biomedical engineering strategies. This article reviews the clinical presentations and classification of nerve injuries, in addition to the state of the art for surgical decision-making and repair strategies. This discussion presents specific challenges that must be addressed to realistically improve the treatment of nerve injuries and promote widespread recovery. In particular, nerve defects a few centimeters in length use a sensory nerve autograft as the standard technique; however, this approach is limited by the availability of donor nerve and comorbidity associated with additional surgery. Moreover, we currently have an inadequate ability to noninvasively assess the degree of nerve injury and to track axonal regeneration. As a result, wait-and-see surgical decisions can lead to undesirable and less successful "delayed" repair procedures. In this fight for time, degeneration of the distal nerve support structure and target progresses, ultimately blunting complete functional recovery. Thus, the most pressing challenges in peripheral nerve repair include the development of tissue-engineered nerve grafts that match or exceed the performance of autografts, the ability to noninvasively assess nerve damage and track axonal regeneration, and approaches to maintain the efficacy of the distal pathway and targets during the regenerative process. Biomedical engineering strategies can address these issues to substantially contribute at both the basic and applied levels, improving surgical management and functional recovery following severe peripheral nerve injury.

  18. The 2015 Nobel Prize in Chemistry The Discovery of Essential Mechanisms that Repair DNA Damage.

    Science.gov (United States)

    Lindahl, Tomas; Modrich, Paul; Sancar, Aziz

    2016-01-01

    The Royal Swedish Academy awarded the Nobel Prize in Chemistry for 2015 to Tomas Lindahl, Paul Modrich and Aziz Sancar for their discoveries in fundamental mechanisms of DNA repair. This pioneering research described three different essential pathways that correct DNA damage, safeguard the integrity of the genetic code to ensure its accurate replication through generations, and allow proper cell division. Working independently of each other, Tomas Lindahl, Paul Modrich and Aziz Sancar delineated the mechanisms of base excision repair, mismatch repair and nucleotide excision repair, respectively. These breakthroughs challenged and dismissed the early view that the DNA molecule was very stable, paving the way for the discovery of human hereditary diseases associated with distinct DNA repair deficiencies and a susceptibility to cancer. It also brought a deeper understanding of cancer as well as neurodegenerative or neurological diseases, and let to novel strategies to treat cancer.

  19. Mechanical Engineering Practice – using a simple Stirling engine as case

    DEFF Research Database (Denmark)

    Meyer, Knud Erik

    2011-01-01

    The first technical course that students in mechanical engineering take at the Technical University of Denmark is called “Mechanical Engineering Practice”. We have used a simple Stirling engine as a design-implement project. Students were asked to design and build a heat engine using materials....... The Stirling engine worked well in the drawing assignments. The Stirling engine also served as illustration of coming courses in mechanical engineering. The resulting engines had large variations in their design and most groups succeeded in building a functioning engine. However, achieved efficiencies were...

  20. Mechanical Engineering Practice – using a simple Stirling engine as case

    DEFF Research Database (Denmark)

    Meyer, Knud Erik

    2011-01-01

    The first technical course that students in mechanical engineering take at the Technical University of Denmark is called “Mechanical Engineering Practice”. We have used a simple Stirling engine as a design-implement project. Students were asked to design and build a heat engine using materials....... The Stirling engine worked well in the drawing assignments. The Stirling engine also served as illustration of coming courses in mechanical engineering. The resulting engines had large variations in their design and most groups succeeded in building a functioning engine. However, achieved efficiencies were...

  1. Tissue-engineering strategies to repair joint tissue in osteoarthritis: nonviral gene-transfer approaches.

    Science.gov (United States)

    Madry, Henning; Cucchiarini, Magali

    2014-10-01

    Loss of articular cartilage is a common clinical consequence of osteoarthritis (OA). In the past decade, substantial progress in tissue engineering, nonviral gene transfer, and cell transplantation have provided the scientific foundation for generating cartilaginous constructs from genetically modified cells. Combining tissue engineering with overexpression of therapeutic genes enables immediate filling of a cartilage defect with an engineered construct that actively supports chondrogenesis. Several pioneering studies have proved that spatially defined nonviral overexpression of growth-factor genes in constructs of solid biomaterials or hydrogels is advantageous compared with gene transfer or scaffold alone, both in vitro and in vivo. Notably, these investigations were performed in models of focal cartilage defects, because advanced cartilage-repair strategies based on the principles of tissue engineering have not advanced sufficiently to enable resurfacing of extensively degraded cartilage as therapy for OA. These studies serve as prototypes for future technological developments, because they raise the possibility that cartilage constructs engineered from genetically modified chondrocytes providing autocrine and paracrine stimuli could similarly compensate for the loss of articular cartilage in OA. Because cartilage-tissue-engineering strategies are already used in the clinic, combining tissue engineering and nonviral gene transfer could prove a powerful approach to treat OA.

  2. Tissue engineering for articular cartilage repair – the state of the art

    Directory of Open Access Journals (Sweden)

    B Johnstone

    2013-05-01

    Full Text Available Articular cartilage exhibits little capacity for intrinsic repair, and thus even minor injuries or lesions may lead to progressive damage and osteoarthritic joint degeneration, resulting in significant pain and disability. While there have been numerous attempts to develop tissue-engineered grafts or patches to repair focal chondral and osteochondral defects, there remain significant challenges in the clinical application of cell-based therapies for cartilage repair. This paper reviews the current state of cartilage tissue engineering with respect to different cell sources and their potential genetic modification, biomaterial scaffolds and growth factors, as well as preclinical testing in various animal models. This is not intended as a systematic review, rather an opinion of where the field is moving in light of current literature. While significant advances have been made in recent years, the complexity of this problem suggests that a multidisciplinary approach – combining a clinical perspective with expertise in cell biology, biomechanics, biomaterials science and high-throughput analysis will likely be necessary to address the challenge of developing functional cartilage replacements. With this approach we are more likely to realise the clinical goal of treating both focal defects and even large-scale osteoarthritic degenerative changes in the joint.

  3. Tissue engineering for articular cartilage repair--the state of the art.

    Science.gov (United States)

    Johnstone, Brian; Alini, Mauro; Cucchiarini, Magali; Dodge, George R; Eglin, David; Guilak, Farshid; Madry, Henning; Mata, Alvaro; Mauck, Robert L; Semino, Carlos E; Stoddart, Martin J

    2013-05-02

    Articular cartilage exhibits little capacity for intrinsic repair, and thus even minor injuries or lesions may lead to progressive damage and osteoarthritic joint degeneration, resulting in significant pain and disability. While there have been numerous attempts to develop tissue-engineered grafts or patches to repair focal chondral and osteochondral defects, there remain significant challenges in the clinical application of cell-based therapies for cartilage repair. This paper reviews the current state of cartilage tissue engineering with respect to different cell sources and their potential genetic modification, biomaterial scaffolds and growth factors, as well as preclinical testing in various animal models. This is not intended as a systematic review, rather an opinion of where the field is moving in light of current literature. While significant advances have been made in recent years, the complexity of this problem suggests that a multidisciplinary approach - combining a clinical perspective with expertise in cell biology, biomechanics, biomaterials science and high-throughput analysis will likely be necessary to address the challenge of developing functional cartilage replacements. With this approach we are more likely to realise the clinical goal of treating both focal defects and even large-scale osteoarthritic degenerative changes in the joint.

  4. Refrigeration Controls: Electrical & Mechanical; Appliance Repair 3: 9027.02.

    Science.gov (United States)

    Dade County Public Schools, Miami, FL.

    This booklet outlines a course designed to equip major appliance service students with the fundamental knowledge and understanding of procedures, basic electrical circuitry, and nomenclatures of components necessary in successfully tracing a circuit and repairing or replacing a malfunctioning component. Course content includes goals, specific…

  5. Cell and protein compatible 3D bioprinting of mechanically strong constructs for bone repair.

    Science.gov (United States)

    Sawkins, M J; Mistry, P; Brown, B N; Shakesheff, K M; Bonassar, L J; Yang, J

    2015-07-02

    Rapid prototyping of bone tissue engineering constructs often utilizes elevated temperatures, organic solvents and/or UV light for materials processing. These harsh conditions may prevent the incorporation of cells and therapeutic proteins in the fabrication processes. Here we developed a method for using bioprinting to produce constructs from a thermoresponsive microparticulate material based on poly(lactic-co-glycolic acid) at ambient conditions. These constructs could be engineered with yield stresses of up to 1.22 MPa and Young's moduli of up to 57.3 MPa which are within the range of properties of human cancellous bone. Further study showed that protein-releasing microspheres could be incorporated into the bioprinted constructs. The release of the model protein lysozyme from bioprinted constructs was sustainted for a period of 15 days and a high degree of protein activity could be measured up to day 9. This work suggests that bioprinting is a viable route to the production of mechanically strong constructs for bone repair under mild conditions which allow the inclusion of viable cells and active proteins.

  6. DNA Repair Mechanisms and Their Biological Roles in the Malaria Parasite Plasmodium falciparum

    Science.gov (United States)

    Lee, Andrew H.; Symington, Lorraine S.

    2014-01-01

    SUMMARY Research into the complex genetic underpinnings of the malaria parasite Plasmodium falciparum is entering a new era with the arrival of site-specific genome engineering. Previously restricted only to model systems but now expanded to most laboratory organisms, and even to humans for experimental gene therapy studies, this technology allows researchers to rapidly generate previously unattainable genetic modifications. This technological advance is dependent on DNA double-strand break repair (DSBR), specifically homologous recombination in the case of Plasmodium. Our understanding of DSBR in malaria parasites, however, is based largely on assumptions and knowledge taken from other model systems, which do not always hold true in Plasmodium. Here we describe the causes of double-strand breaks, the mechanisms of DSBR, and the differences between model systems and P. falciparum. These mechanisms drive basic parasite functions, such as meiosis, antigen diversification, and copy number variation, and allow the parasite to continually evolve in the contexts of host immune pressure and drug selection. Finally, we discuss the new technologies that leverage DSBR mechanisms to accelerate genetic investigations into this global infectious pathogen. PMID:25184562

  7. DNA repair mechanisms and their biological roles in the malaria parasite Plasmodium falciparum.

    Science.gov (United States)

    Lee, Andrew H; Symington, Lorraine S; Fidock, David A

    2014-09-01

    Research into the complex genetic underpinnings of the malaria parasite Plasmodium falciparum is entering a new era with the arrival of site-specific genome engineering. Previously restricted only to model systems but now expanded to most laboratory organisms, and even to humans for experimental gene therapy studies, this technology allows researchers to rapidly generate previously unattainable genetic modifications. This technological advance is dependent on DNA double-strand break repair (DSBR), specifically homologous recombination in the case of Plasmodium. Our understanding of DSBR in malaria parasites, however, is based largely on assumptions and knowledge taken from other model systems, which do not always hold true in Plasmodium. Here we describe the causes of double-strand breaks, the mechanisms of DSBR, and the differences between model systems and P. falciparum. These mechanisms drive basic parasite functions, such as meiosis, antigen diversification, and copy number variation, and allow the parasite to continually evolve in the contexts of host immune pressure and drug selection. Finally, we discuss the new technologies that leverage DSBR mechanisms to accelerate genetic investigations into this global infectious pathogen.

  8. Research Skills Enhancement in Future Mechanical Engineers

    Directory of Open Access Journals (Sweden)

    Jorge Lino Alves

    2011-04-01

    Full Text Available Nowadays, the Web is a common tool for students searching information about the subjects taught in the different university courses. Although this is a good tool for the first rapid knowledge, a deeper study is usually demanded.

    After many years of teaching a course about ceramic and composite materials in the Integrated Master in Mechanical Engineering of Faculty of Engineering of University of Porto, Portugal, the authors used the Bologna reformulation of the mechanical engineering course to introduce new teaching methodologies based on a project based learning methodology.

    One of the main innovations is a practical work that comprises the study of a recent ceramic scientific paper, using all the actual available tools, elaboration of a scientific report, work presentation and participation in a debate.

    With this innovative teaching method the enrolment of the students was enhanced with a better knowledge about the ceramics subject and the skills related with the CDIO competences.

    This paper presents the reasons for this implementation and explains the teaching methodology adopted as well as the changes obtained in the students’ final results.

  9. Thermal integrity in mechanics and engineering

    Energy Technology Data Exchange (ETDEWEB)

    Shorr, Boris F. [Central Institute of Aviation Motors (CIAM), Moscow (Russian Federation)

    2015-07-01

    The book is targeted at engineers, university lecturers, postgraduates, and final year undergraduate students involved in computational modelling and experimental and theoretical analysis of the high-temperature behavior of engineering structures. It will also be of interest to researchers developing the thermal strength theory as a branch of continuum mechanics. Thermal integrity is a multidisciplinary field combining the expertise of mechanical engineers, material scientists and applied mathematicians, each approaching the problem from their specific viewpoint. This monograph draws on the research of a broad scientific community including the author's contribution. The scope of thermal strength analysis was considerably extended thanks to modern computers and the implementation of FEM codes. However, the author believes that some material models adopted in the advanced high-performance software, are not sufficiently justificated due to lack of easy-to-follow books on the theoretical and experimental aspects of thermal integrity. The author endeavors to provide a thorough yet sufficiently simple presentation of the underlying concepts, making the book compelling to a wide audience.

  10. Study on Self-Repairing Performance of Mineral Powder Lubrication Oil Additive to Engine

    Institute of Scientific and Technical Information of China (English)

    GUO Yan-bao; XU Bin-shi; XU Yi

    2004-01-01

    By means of the engine shelf test, the gas escape amount of bent axle box was measured before and after adding hydroxyl silicate mineral powder lubrication oil additives, and discovered that gas escape amount after self-repaired is obviously smaller than before, the average gas escape amount of each rotate speed descend 6.5 %. Watching friction surface with SEM, discovered that the part of net veins in the cylinder inner surface are smoothly patched. Analysis with energy spectroscopy, discovered that there are some changing of atom component. Proofed that through rub chemical reaction, hydroxyl silicate mineral powder lubrication oil additives can generate new substance layer on friction surface, and can increase cylinder inner surface bulk, thereby get the repaired effects.

  11. Simulation based engineering in solid mechanics

    CERN Document Server

    Rao, J S

    2017-01-01

    This book begins with a brief historical perspective of the advent of rotating machinery in 20th century Solid Mechanics and the development of the discipline of the Strength of Materials. High Performance Computing (HPC) and Simulation Based Engineering Science (SBES) have gradually replaced the conventional approach in Design bringing science directly into engineering without approximations. A recap of the required mathematical principles is given. The science of deformation, strain and stress at a point under the application of external traction loads is next presented. Only one-dimensional structures classified as Bars (axial loads), Rods (twisting loads) and Beams (bending loads) are considered in this book. The principal stresses and strains and von Mises stress and strain that used in design of structures are next presented. Lagrangian solution was used to derive the governing differential equations consistent with assumed deformation field and solution for deformations, strains and stresses were obtai...

  12. Superconducting Qubits as Mechanical Quantum Engines

    Science.gov (United States)

    Sachtleben, Kewin; Mazon, Kahio T.; Rego, Luis G. C.

    2017-09-01

    We propose the equivalence of superconducting qubits with a pistonlike mechanical quantum engine. The work reports a study on the nature of the nonequilibrium work exchanged with the quantum-nonadiabatic working medium, which is modeled as a multilevel coupled quantum well system subject to an external control parameter. The quantum dynamics is solved for arbitrary control protocols. It is shown that the work output has two components: one that depends instantaneously on the level populations and another that is due to the quantum coherences built in the system. The nonadiabatic coherent dynamics of the quantum engine gives rise to a resistance (friction) force that decreases the work output. We consider the functional equivalence of such a device and a rf-SQUID flux qubit.

  13. Propulsion Mechanism of Catalytic Microjet Engines

    Science.gov (United States)

    Fomin, Vladimir M.; Hippler, Markus; Magdanz, Veronika; Soler, Lluís; Sanchez, Samuel; Schmidt, Oliver G.

    2014-01-01

    We describe the propulsion mechanism of the catalytic microjet engines that are fabricated using rolled-up nanotech. Microjets have recently shown numerous potential applications in nanorobotics but currently there is a lack of an accurate theoretical model that describes the origin of the motion as well as the mechanism of self-propulsion. The geometric asymmetry of a tubular microjet leads to the development of a capillary force, which tends to propel a bubble toward the larger opening of the tube. Because of this motion in an asymmetric tube, there emerges a momentum transfer to the fluid. In order to compensate this momentum transfer, a jet force acting on the tube occurs. This force, which is counterbalanced by the linear drag force, enables tube velocities of the order of 100 μm/s. This mechanism provides a fundamental explanation for the development of driving forces that are acting on bubbles in tubular microjets. PMID:25177214

  14. Essays on the history of mechanical engineering

    CERN Document Server

    Genchi, Giuseppe

    2016-01-01

    This book treats several subjects from the History of Mechanism and Machine Science, and also contains an illustrative presentation of the Museum of Engines and Mechanisms of the University of Palermo, Italy, which houses a collection of various pieces of machinery from the last 150 years. The various sections deal with some eminent scientists of the past, with the history of industrial installations, machinery and transport, with the human inventiveness for mechanical and scientific devices, and with robots and human-driven automata. All chapters have been written by experts in their fields. The volume shows a wide-ranging panorama on the historical progress of scientific and technical knowledge in the past centuries. It will stimulate new research and ideas for those involved in the history of Science and Technology.

  15. Selective Guide to Literature on Mechanical Engineering. Engineering Literature Guides, Number 2.

    Science.gov (United States)

    Franklin, Hugh Lockwood, Comp.

    Mechanical engineering has become highly interdisciplinary. It would not be possible to single out particular reference sources that are uniquely applicable to mechanical engineering. For the purpose of this guide, mechanical engineering deals with the generation, transmission and utilization of heat and mechanical power and with the production of…

  16. Multi-axial mechanical stimulation of tissue engineered cartilage: Review

    Directory of Open Access Journals (Sweden)

    S D Waldman

    2007-04-01

    Full Text Available The development of tissue engineered cartilage is a promising new approach for the repair of damaged or diseased tissue. Since it has proven difficult to generate cartilaginous tissue with properties similar to that of native articular cartilage, several studies have used mechanical stimuli as a means to improve the quantity and quality of the developed tissue. In this study, we have investigated the effect of multi-axial loading applied during in vitro tissue formation to better reflect the physiological forces that chondrocytes are subjected to in vivo. Dynamic combined compression-shear stimulation (5% compression and 5% shear strain amplitudes increased both collagen and proteoglycan synthesis (76 ± 8% and 73 ± 5%, respectively over the static (unstimulated controls. When this multi-axial loading condition was applied to the chondrocyte cultures over a four week period, there were significant improvements in both extracellular matrix (ECM accumulation and the mechanical properties of the in vitro-formed tissue (3-fold increase in compressive modulus and 1.75-fold increase in shear modulus. Stimulated tissues were also significantly thinner than the static controls (19% reduction suggesting that there was a degree of ECM consolidation as a result of long-term multi-axial loading. This study demonstrated that stimulation by multi-axial forces can improve the quality of the in vitro-formed tissue, but additional studies are required to further optimize the conditions to favour improved biochemical and mechanical properties of the developed tissue.

  17. DNA DSB repair pathway choice: an orchestrated handover mechanism.

    Science.gov (United States)

    Kakarougkas, A; Jeggo, P A

    2014-03-01

    DNA double strand breaks (DSBs) are potential lethal lesions but can also lead to chromosome rearrangements, a step promoting carcinogenesis. DNA non-homologous end-joining (NHEJ) is the major DSB rejoining process and occurs in all cell cycle stages. Homologous recombination (HR) can additionally function to repair irradiation-induced two-ended DSBs in G2 phase. In mammalian cells, HR predominantly uses a sister chromatid as a template for DSB repair; thus HR functions only in late S/G2 phase. Here, we review current insight into the interplay between HR and NHEJ in G2 phase. We argue that NHEJ represents the first choice pathway, repairing approximately 80% of X-ray-induced DSBs with rapid kinetics. However, a subset of DSBs undergoes end resection and repair by HR. 53BP1 restricts resection, thereby promoting NHEJ. During the switch from NHEJ to HR, 53BP1 is repositioned to the periphery of enlarged irradiation-induced foci (IRIF) via a BRCA1-dependent process. K63-linked ubiquitin chains, which also form at IRIF, are also repositioned as well as receptor-associated protein 80 (RAP80), a ubiquitin binding protein. RAP80 repositioning requires POH1, a proteasome component. Thus, the interfacing barriers to HR, 53BP1 and RAP80 are relieved by POH1 and BRCA1, respectively. Removal of RAP80 from the IRIF core is required for loss of the ubiquitin chains and 53BP1, and for efficient replication protein A foci formation. We propose that NHEJ is used preferentially to HR because it is a compact process that does not necessitate extensive chromatin changes in the DSB vicinity.

  18. Biological effects of exposure to intermediate neutron and repair mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Utsumi, Hiroshi; Sasaki, Masao [Kyoto Univ. (Japan); Onishi, Takeo; Onizuka, Masahiko

    2000-01-01

    An investigation was made on cytotoxic effects of neutron capture using chicken B-cell line mutants, DT40, KURO{sup -/-}, RAD54 {sup -/-} and KU70{sup -/-} / RAD54{sup -/-}. Suspensions of these cells were exposed to two times X-radiation at various doses and the cell surviving was evaluated. The sensitivity to radiation was highest in the double defective mutant, KU70{sup -/-} / RAD54{sup -/-} and followed by that of RAD54 {sup -/-}, a homologous recombination mutant, whereas KURO {sup -/-} cell, a non-homologous end-joining mutant showed a peculiar surviving curve composed of two phases and the cell was highly sensitive to a low-dose radiation. This indicates that there are two different DNA repair systems for double-strand breaks and the system for non-homologous end-joining repair can be involved in all phases of cell cycle, but the system for the homologous one is involved only in S-phase. Therefore, it was thought that variation of sensitivity to radiation exposure depending to the phase of cell cycle might explain the alternation of repair system depending to the phase progressing of cell cycle. It was thus likely that the recovery from radiation injury, which is still a black box might be explained with the double strand breaks of DNA. (M.N.)

  19. Mechanics of materials an introduction to engineering technology

    CERN Document Server

    Ghavami, Parviz

    2015-01-01

    This book, framed in the processes of engineering analysis and design, presents concepts in mechanics of materials for students in two-year or four-year programs in engineering technology, architecture, and building construction, as well as for students in vocational schools and technical institutes. Using the principles and laws of mechanics, physics, and the fundamentals of engineering, Mechanics of Materials: An Introduction for Engineering Technology will help aspiring and practicing engineers and engineering technicians from across disciplines—mechanical, civil, chemical, and electrical—apply concepts of engineering mechanics for analysis and design of materials, structures, and machine components. The book is ideal for those seeking a rigorous, algebra/trigonometry-based text on the mechanics of materials. This book also: ·       Elucidates concepts of engineering mechanics in materials, including stress and strain, force systems on structures, moment of inertia, and shear and bending moments...

  20. Engineering a multimodal nerve conduit for repair of injured peripheral nerve

    Science.gov (United States)

    Quigley, A. F.; Bulluss, K. J.; Kyratzis, I. L. B.; Gilmore, K.; Mysore, T.; Schirmer, K. S. U.; Kennedy, E. L.; O'Shea, M.; Truong, Y. B.; Edwards, S. L.; Peeters, G.; Herwig, P.; Razal, J. M.; Campbell, T. E.; Lowes, K. N.; Higgins, M. J.; Moulton, S. E.; Murphy, M. A.; Cook, M. J.; Clark, G. M.; Wallace, G. G.; Kapsa, R. M. I.

    2013-02-01

    hydrogel. This indicates return of some feeling to the limb via the fully-configured conduit. Immunohistochemical analysis of the implanted conduits removed from the rats after the four-week implantation period confirmed the presence of myelinated axons within the conduit and distal to the site of implantation, further supporting that the conduit promoted nerve repair over this period of time. This study describes the design considerations and fabrication of a novel multicomponent, multimodal bio-engineered synthetic conduit for peripheral nerve repair.

  1. QUALITY IMPROVEMENT OF ESP IN MECHANICAL ENGINEERING

    Directory of Open Access Journals (Sweden)

    Alina-Andreea Dragoescu

    2010-09-01

    Full Text Available The latest political positioning of Serbia has caused many changes in the society with the most dramatic economic shift on the market. The market requires young educated employees with special additional "soft skills". This has resulted in the need to change the Serbian educational system with the Bologna process implemented. Therefore, the syllabus of ESP in Mechanical Engineering must be adjusted to the demands as regards needs analysis so that it can meet the requirements of the rapidly growing market. This paper offers an outline of ESP syllabus which can be regularly updated with respect to technological and other changes on the market.

  2. Nerve autografts and tissue-engineered materials for the repair of peripheral nerve injuries: a 5-year bibliometric analysis

    Directory of Open Access Journals (Sweden)

    Yuan Gao

    2015-01-01

    Full Text Available With advances in biomedical methods, tissue-engineered materials have developed rapidly as an alternative to nerve autografts for the repair of peripheral nerve injuries. However, the materials selected for use in the repair of peripheral nerve injuries, in particular multiple injuries and large-gap defects, must be chosen carefully. Various methods and materials for protecting the healthy tissue and repairing peripheral nerve injuries have been described, and each method or material has advantages and disadvantages. Recently, a large amount of research has been focused on tissue-engineered materials for the repair of peripheral nerve injuries. Using the keywords "pe-ripheral nerve injury", "autotransplant", "nerve graft", and "biomaterial", we retrieved publications using tissue-engineered materials for the repair of peripheral nerve injuries appearing in the Web of Science from 2010 to 2014. The country with the most total publications was the USA. The institutions that were the most productive in this field include Hannover Medical School (Germany, Washington University (USA, and Nantong University (China. The total number of publications using tissue-engineered materials for the repair of peripheral nerve injuries grad-ually increased over time, as did the number of Chinese publications, suggesting that China has made many scientific contributions to this field of research.

  3. Mechanisms of renal cell repair and regeneration after acute renal failure.

    Science.gov (United States)

    Nony, Paul A; Schnellmann, Rick G

    2003-03-01

    In many cases, acute renal failure (ARF) is the result of proximal tubular cell injury and death and can arise in a variety of clinical situations, especially following renal ischemia and drug or toxicant exposure. Although much research has focused on the cellular events leading to ARF, less emphasis has been placed on the mechanisms of renal cell repair and regeneration, although ARF is reversed in over half of those who acquire it. Studies using in vivo and in vitro models have demonstrated the importance of proliferation, migration, and repair of physiological functions of injured renal proximal tubular cells (RPTC) in the reversal of ARF. Growth factors have been shown to produce migration and proliferation of injured RPTC, although the specific mechanisms through which growth factors promote renal regeneration in vivo are unclear. Recently, interactions between integrins and extracellular matrix proteins such as collagen IV were shown to promote the repair of physiological functions in injured RPTC. Specifically, collagen IV synthesis and deposition following cellular injury restored integrin polarity and promoted repair of mitochondrial function and active Na(+) transport. Furthermore, exogenous collagen IV, but not collagen I, fibronectin, or laminin, promoted the repair of physiological functions without stimulating proliferation. These findings suggest the importance of establishing and/or maintaining collagen IV-integrin interactions in the stimulation of repair of physiological functions following sublethal cellular injury. Furthermore, the pathway that stimulates repair is distinct from that of proliferation and migration and may be a viable target for pharmacological intervention.

  4. Stirling engine control mechanism and method

    Science.gov (United States)

    Dineen, John J.

    1983-01-01

    A reciprocating-to-rotating motion conversion and power control device for a Stirling engine includes a hub mounted on an offset portion of the output shaft for rotation relative to the shaft and for sliding motion therealong which causes the hub to tilt relative to the axis of rotation of the shaft. This changes the angle of inclination of the hub relative to the shaft axis and changes the axial stroke of a set of arms connected to the hub and nutating therewith. A hydraulic actuating mechanism is connected to the hub for moving its axial position along the shaft. A balancing wheel is linked to the hub and changes its angle of inclination as the angle of inclination of the hub changes to maintain the mechanism in perfect balance throughout its range of motion.

  5. CDIO CURRICULUM FOR MECHANICAL ENGINEERING UNDERGRADUATE COURSE

    Directory of Open Access Journals (Sweden)

    ABDULKAREEM SH. MAHDI

    2011-04-01

    Full Text Available A unique approach to the use of the Project Based Learning to transform the curriculum into CDIO curriculum is achieved through the use of carefully selected projects for the Engineering Design modules (which are Project Based by nature and use these modules as platforms to encourage practical engagement in other concurrently offered modules which are traditionally viewed as theory based modules. Simple as it may look, this approach requires a high level of coordination on the part of the lecturers delivering the concerned modules to ensure that the required objectives are effectively achieved. This paper reports on the use of the “Engineering Design and Professional Skills” module, offered at the second semester of the second year of a four-year Mechanical Engineering course, in conjunction with a theory based module namely: “Flows with Friction, Drag & Lift” offered at the same semester, to create a CDIO environment without introducing any major changes to the syllabus of the theory based modules or to their assessment scheme. The students were divided into groups and each group was assigned the task of conceiving, designing, implementing and operating a fluid related project. In brief, the “Flows with Friction, Drag & Lift” provided the theoretical backbone for the project, while the “Engineering Design and Professional Skills” module provided the platform through which the project management and team work skills are developed and the progress of the projects is monitored. The students exhibited a high level of engagement and motivation while gaining a better understanding of the real fluids related theory.

  6. Cell-based tissue engineering strategies used in the clinical repair of articular cartilage

    Science.gov (United States)

    Huang, Brian J.; Hu, Jerry C.; Athanasiou, Kyriacos A.

    2016-01-01

    One of the most important issues facing cartilage tissue engineering is the inability to move technologies into the clinic. Despite the multitude of review articles on the paradigm of biomaterials, signals, and cells, it is reported that 90% of new drugs that advance past animal studies fail clinical trials (1). The intent of this review is to provide readers with an understanding of the scientific details of tissue engineered cartilage products that have demonstrated a certain level of efficacy in humans, so that newer technologies may be developed upon this foundation. Compared to existing treatments, such as microfracture or autologous chondrocyte implantation, a tissue engineered product can potentially provide more consistent clinical results in forming hyaline repair tissue and in filling the entirety of the defect. The various tissue engineering strategies (e.g., cell expansion, scaffold material, media formulations, biomimetic stimuli, etc.) used in forming these products, as collected from published literature, company websites, and relevant patents, are critically discussed. The authors note that many details about these products remain proprietary, not all information is made public, and that advancements to the products are continuously made. Nevertheless, by fully understanding the design and production processes of these emerging technologies, one can gain tremendous insight into how to best use them and also how to design the next generation of tissue engineered cartilage products. PMID:27177218

  7. Repair of acutely injured spinal cord through constructing tissue-engineered neural complex in adult rats

    Institute of Scientific and Technical Information of China (English)

    PU Yu; GUO Qing-shan; WANG Ai-min; WU Si-yu; XING Shu-xing; ZHANG Zhong-rong

    2007-01-01

    Objective: To construct tissue-engineered neural complex in vitro and study its effect in repairing acutely injured spinal cord in adult rats. Methods: Neural stem cells were harvested from the spinal cord of embryo rats and propagated in vitro. Then the neural stem cells were seeded into polyglycolic acid scaffolds and co-cultured with extract of embryonic spinal cord in vitro. Immunofluorescence histochemistry and scanning electron microscope were used to observe the microstructure of this complex. Animal model of spine semi-transection was made and tissue-engineered neural complex was implanted by surgical intervention. Six weeks after transplantation, functional evaluation and histochemistry were applied to evaluate the functional recovery and anatomic reconstruction. Results: The tissue-engineered neural complex had a distinct structure, which contained neonatal neurons, oligodendrocytes and astrocytes. After tissue-engineered neural complex was implanted into the injured spinal cord, the cell components such as neurons, astrocytes and oligodendrocytes, could survive and keep on developing. The adult rats suffering from spinal cord injury got an obvious neurological recovery in motor skills. Conclusions: The tissue-engineered neural complex appears to have therapeutic effects on the functional recovery and anatomic reconstruction of the adult rats with spinal cord injury.

  8. Mechanical testing of hydrogels in cartilage tissue engineering: beyond the compressive modulus.

    Science.gov (United States)

    Xiao, Yinghua; Friis, Elizabeth A; Gehrke, Stevin H; Detamore, Michael S

    2013-10-01

    Injuries to articular cartilage result in significant pain to patients and high medical costs. Unfortunately, cartilage repair strategies have been notoriously unreliable and/or complex. Biomaterial-based tissue-engineering strategies offer great promise, including the use of hydrogels to regenerate articular cartilage. Mechanical integrity is arguably the most important functional outcome of engineered cartilage, although mechanical testing of hydrogel-based constructs to date has focused primarily on deformation rather than failure properties. In addition to deformation testing, as the field of cartilage tissue engineering matures, this community will benefit from the addition of mechanical failure testing to outcome analyses, given the crucial clinical importance of the success of engineered constructs. However, there is a tremendous disparity in the methods used to evaluate mechanical failure of hydrogels and articular cartilage. In an effort to bridge the gap in mechanical testing methods of articular cartilage and hydrogels in cartilage regeneration, this review classifies the different toughness measurements for each. The urgency for identifying the common ground between these two disparate fields is high, as mechanical failure is ready to stand alongside stiffness as a functional design requirement. In comparing toughness measurement methods between hydrogels and cartilage, we recommend that the best option for evaluating mechanical failure of hydrogel-based constructs for cartilage tissue engineering may be tensile testing based on the single edge notch test, in part because specimen preparation is more straightforward and a related American Society for Testing and Materials (ASTM) standard can be adopted in a fracture mechanics context.

  9. DREMECELS: A Curated Database for Base Excision and Mismatch Repair Mechanisms Associated Human Malignancies.

    Directory of Open Access Journals (Sweden)

    Ankita Shukla

    Full Text Available DNA repair mechanisms act as a warrior combating various damaging processes that ensue critical malignancies. DREMECELS was designed considering the malignancies with frequent alterations in DNA repair pathways, that is, colorectal and endometrial cancers, associated with Lynch syndrome (also known as HNPCC. Since lynch syndrome carries high risk (~40-60% for both cancers, therefore we decided to cover all three diseases in this portal. Although a large population is presently affected by these malignancies, many resources are available for various cancer types but no database archives information on the genes specifically for only these cancers and disorders. The database contains 156 genes and two repair mechanisms, base excision repair (BER and mismatch repair (MMR. Other parameters include some of the regulatory processes that have roles in these disease progressions due to incompetent repair mechanisms, specifically BER and MMR. However, our unique database mainly provides qualitative and quantitative information on these cancer types along with methylation, drug sensitivity, miRNAs, copy number variation (CNV and somatic mutations data. This database would serve the scientific community by providing integrated information on these disease types, thus sustaining diagnostic and therapeutic processes. This repository would serve as an excellent accompaniment for researchers and biomedical professionals and facilitate in understanding such critical diseases. DREMECELS is publicly available at http://www.bioinfoindia.org/dremecels.

  10. Kinetic theory approach to modeling of cellular repair mechanisms under genome stress.

    Directory of Open Access Journals (Sweden)

    Jinpeng Qi

    Full Text Available Under acute perturbations from outer environment, a normal cell can trigger cellular self-defense mechanism in response to genome stress. To investigate the kinetics of cellular self-repair process at single cell level further, a model of DNA damage generating and repair is proposed under acute Ion Radiation (IR by using mathematical framework of kinetic theory of active particles (KTAP. Firstly, we focus on illustrating the profile of Cellular Repair System (CRS instituted by two sub-populations, each of which is made up of the active particles with different discrete states. Then, we implement the mathematical framework of cellular self-repair mechanism, and illustrate the dynamic processes of Double Strand Breaks (DSBs and Repair Protein (RP generating, DSB-protein complexes (DSBCs synthesizing, and toxins accumulating. Finally, we roughly analyze the capability of cellular self-repair mechanism, cellular activity of transferring DNA damage, and genome stability, especially the different fates of a certain cell before and after the time thresholds of IR perturbations that a cell can tolerate maximally under different IR perturbation circumstances.

  11. NANO SCIENCE AND ENGINEERING IN SOLID MECHANICS

    Institute of Scientific and Technical Information of China (English)

    Ken P. Chong

    2008-01-01

    According to National Science Foundation (NSF) Director A. Bement, 'Transformative research is... Research driven by ideas that stand a reasonable chance of radically changing our understanding of an important existing scientific concept or leading to the creation of a new paradigm or field of science... is also characterized by its challenge to current understanding or its pathway to new frontiers.' Nanotechnology is one of such frontiers. It is the creation of new materials, devices and systems at the molecular level --phenomena associated with atomic and molecular interactions strongly influence macroscopic material properties with significantly im-proved mechanical, optical, chemical, electrical... Properties. Former NSF Director Rita ColweU in 2002 declared, 'nanoscale technology will have an impact equal to the Industrial Revolution'. The transcendent technologies include nanotechnology, microelectronics, information technology and biotechnology as well as the enabling and supporting mechanical and civil infrastructure sys-tems and materials. These technologies are the primary drivers of the twenty first century and the new economy. Mechanics is an essential element in all of the transcendent technologies. Re-search opportunities, education and challenges in mechanics, including experimental, numerical and analytical methods in nanomechanics, carbon nano-tubes, bio-inspired materials, fuel cells, as well as improved engineering and design of materials are presented and discussed in this paper.

  12. Repair of Sheep Metatarsus Defects by Using Tissue-engineering Technique

    Institute of Scientific and Technical Information of China (English)

    LI Zhanghua; YANG Yi; WANG Changyong; XIA Renyun; ZHANG Yufu; ZHAO Qiang; LIAO Wen; WANG Yonghong; LU Jianxi

    2005-01-01

    Tissue-engineering bone with porous β-tricalcium phosphate (β-TCP) ceramic and autologous bone marrow mesenchymal stem cells (MSC) was constructed and the effect of this composite on healing of segmental bone defects was investigated. 10-15 ml bone marrow aspirates were harvested from the iliac crestof sheep, and enriched for MSC by density gradient centrifugation over a Percoll cushion (1. 073 g/ml). After cultured and proliferated, tissue-engineering bones were constructed with these cells seeded onto porous β-TCP, and then the constructs were implanted in 8 sheep left metatarsus defect (25 mm in length) as experimental group. Porous β-TCP only were implanted to bridge same size and position defects in 8 sheep as control group, and 25 mm segmental bone defects of left metatarsus were left empty in 4 sheep as blank group. Sheep were sacrificed on the 6th, 12th, and 24th week postoperatively and the implants samples were examined by radiograph, histology, and biomechanical test. The 4 sheep in blank group were sacrificed on the 24th week postoperatively. The results showed that new bone tissues were observed either radiographic or histologically at the defects of experimental group as early as 6th week postoperatively, but not in control group, and osteoid tissue, woven bone and lamellar bone occurred earlier than in control group in which the bone defects were repaired in "creep substitution" way, because of the new bone formed in direct manner without progression through a cartilaginous intermediate. At the 24th week, radiographs and biomechanical test revealed an almost complete repair of the defect of experimental group, only partly in control group. The bone defects in blank group were non-healing at the 24th week. It was concluded that engineering bones constructed with porous β-TCP and autologous MSC were capable of repairing segmental bone defects in sheep metatarsus beyond "creep substitution" way and making it healed earlier. Porous β-TCP being

  13. Repair of flexor tendon defects of rabbit with tissue engineering method

    Institute of Scientific and Technical Information of China (English)

    何清义; 李起鸿; 陈秉礼; 王智彪

    2002-01-01

    To repair rabbit tendon defects with tissue engineering method. Methods: The third passage of fetal skin fibroblast cells was labeled with 5-bromo-2' deoxyuridine (Brdu) and then seeded on human amnion extracellular matrix (HA-ECM). Using 1 cm-long-Achilles tendon .defects as repairing models in the experimental group, tendon defects were core bridged with polydioxanone (PDS) and then capsulated with the complex of fibroblasts-HA-ECM. In the control group I, defective tendons were sutured with PDS following the former procedure and capsulated with HA-ECM (without fibroblasts). In the control group Ⅱ,only PDS was applied to connect the defective tendons.Gross examination, light microscopy, scanning electronmicroscopy and biomechanical measurement of the repaired tendons were respectively performed at postoperative 1, 2, 3 month as well as immunohistochemical examination. Results: The optimal cell concentration for seeding fibroblasts was 3.5 × 106 cells/ml. Cells grew well and radiated or paralleled on HA-ECM. Immunohistochemistry showed that the labeled seed fibroblasts played an important role in tendonization. The results of light microscopy,electron microscopy, and biomechanical assessment suggested that the rate and quality of tendonization in the experimental group was superior to those of the control group Ⅰ and Ⅱ. The tensile strength in the experimental group was the greatest, the next was in the control group Ⅰ,and the worst in the control group Ⅱ ( P < 0.05). Conclusions: HA-ECM is the excellent carrier for fibroblasts. Fibroblasts-HA-ECM complex has the capability to repair tendon defect and to tendonize with rapid rate and good performance three months after operation. Its tensile strength is 81.8% of that of normal tendon.

  14. Geometry of surfaces a practical guide for mechanical engineers

    CERN Document Server

    Radzevich, Stephen P

    2012-01-01

    Presents an in-depth analysis of geometry of part surfaces and provides the tools for solving complex engineering problems Geometry of Surfaces: A Practical Guide for Mechanical Engineers is a comprehensive guide to applied geometry of surfaces with focus on practical applications in various areas of mechanical engineering. The book is divided into three parts on Part Surfaces, Geometry of Contact of Part Surfaces and Mapping of the Contacting Part Surfaces. Geometry of Surfaces: A Practical Guide for Mechanical Engineers combines differential geometry and gearing theory and presents new developments in the elementary theory of enveloping surfaces. Written by a leading expert of the field, this book also provides the reader with the tools for solving complex engineering problems in the field of mechanical engineering. Presents an in-depth analysis of geometry of part surfaces Provides tools for solving complex engineering problems in the field of mechanical engineering Combines differential geometry an...

  15. International Conference on Research and Innovations in Mechanical Engineering

    CERN Document Server

    Singh, Paramjit; Singh, Harwinder; Brar, Gurinder

    2014-01-01

    This book comprises the proceedings of International Conference on Research and Innovations in Mechanical Engineering (ICRIME 2013) organized by Guru Nanak Dev Engineering College, Ludhiana with support from AICTE, TEQIP, DST and PTU, Jalandhar. This international conference served as a premier forum for communication of new advances and research results in the fields of mechanical engineering. The proceedings reflect the conference’s emphasis on strong methodological approaches and focus on applications within the domain of mechanical engineering. The contents of this volume aim to highlight new theoretical and experimental findings in the fields of mechanical engineering and closely related fields, including interdisciplinary fields such as robotics and mechatronics.

  16. Condition and prospects of development of agricultural mechanical engineering

    Directory of Open Access Journals (Sweden)

    Vsevolod Petrovich Babushkin

    2011-12-01

    Full Text Available In this paper, an estimation of condition and level of development of agricultural mechanical engineering is given; also an expert estimation of scales of the Russian market of agricultural machinery is given. The factors negatively influencing formation of the named market are designated. Features and prospects of development of agricultural mechanical engineering of Sverdlovsk region are defined. State regulation mechanisms of domestic agricultural mechanical engineering development are designated.

  17. Molecular Mechanisms of Ultraviolet Radiation-Induced DNA Damage and Repair

    Directory of Open Access Journals (Sweden)

    Rajesh P. Rastogi

    2010-01-01

    Full Text Available DNA is one of the prime molecules, and its stability is of utmost importance for proper functioning and existence of all living systems. Genotoxic chemicals and radiations exert adverse effects on genome stability. Ultraviolet radiation (UVR (mainly UV-B: 280–315 nm is one of the powerful agents that can alter the normal state of life by inducing a variety of mutagenic and cytotoxic DNA lesions such as cyclobutane-pyrimidine dimers (CPDs, 6-4 photoproducts (6-4PPs, and their Dewar valence isomers as well as DNA strand breaks by interfering the genome integrity. To counteract these lesions, organisms have developed a number of highly conserved repair mechanisms such as photoreactivation, base excision repair (BER, nucleotide excision repair (NER, and mismatch repair (MMR. Additionally, double-strand break repair (by homologous recombination and nonhomologous end joining, SOS response, cell-cycle checkpoints, and programmed cell death (apoptosis are also operative in various organisms with the expense of specific gene products. This review deals with UV-induced alterations in DNA and its maintenance by various repair mechanisms.

  18. Thermo-mechanical cracking of a new and laser repair welded die casting die

    Directory of Open Access Journals (Sweden)

    D. Klobčar

    2012-07-01

    Full Text Available The paper presents the analysis of thermo-mechanical fatigue cracking of die casting die during industrial use. An innovative, production friendly approach to monitor the surface crack dimensions was introduced, which is based on measuring defect-fin on the casting part. A new four moulds die casting die was monitored 40 000 cycles in order to complete the production series. The production was stopped three times for laser repair welding of cracks since the defect-fins were not acceptable. The defect-fin heights were measured every 1 000 cycles on the castings before and after repair welding of die surface cracks. The in-service die life can be prolonged with laser repair welding for several times, even thought that in-service die life for a particular repair varies.

  19. Sharpening the ends for repair: mechanisms and regulation of DNA resection

    Institute of Scientific and Technical Information of China (English)

    Sharad C.Paudyal; Zhongsheng You

    2016-01-01

    DNA end resection is a key process in the cellular response to DNA double-strand break damage that is essential for genome maintenance and cell survival.Resection involves selective processing of 5' ends of broken DNA to generate ssDNA overhangs,which in turn control both DNA repair and checkpoint signaling.DNA resection is the first step in homologous recombination-mediated repair and a prerequisite for the activation of the ataxia telangiectasia mutated and Rad3-related (ATR)-dependent checkpoint that coordinates repair with cell cycle progression and other cellular processes.Resection occurs in a cell cycle-dependent manner and is regulated by multiple factors to ensure an optimal amount of ssDNA required for proper repair and genome stability.Here,we review the latest findings on the molecular mechanisms and regulation of the DNA end resection process and their implications for cancer formation and treatment.

  20. DESIGN OPTIMIZATION METHOD USED IN MECHANICAL ENGINEERING

    Directory of Open Access Journals (Sweden)

    SCURTU Iacob Liviu

    2016-11-01

    Full Text Available This paper presents an optimization study in mechanical engineering. First part of the research describe the structural optimization method used, followed by the presentation of several optimization studies conducted in recent years. The second part of the paper presents the CAD modelling of an agricultural plough component. The beam of the plough is analysed using finite element method. The plough component is meshed in solid elements, and the load case which mimics the working conditions of agricultural equipment of this are created. The model is prepared to find the optimal structural design, after the FEA study of the model is done. The mass reduction of part is the criterion applied for this optimization study. The end of this research presents the final results and the model optimized shape.

  1. 2dF mechanical engineering

    Science.gov (United States)

    Smith, Greg; Lankshear, Allan

    1998-07-01

    2dF is a multi-object instrument mounted at prime focus at the AAT capable of spectroscopic analysis of 400 objects in a single 2 degree field. It also prepares a second 2 degree 400 object field while the first field is being observed. At its heart is a high precision robotic positioner that places individual fiber end magnetic buttons on one of two field plates. The button gripper is carried on orthogonal gantries powered by linear synchronous motors and contains a TV camera which precisely locates backlit buttons to allow placement in user defined locations to 10 (mu) accuracy. Fiducial points on both plates can also be observed by the camera to allow repeated checks on positioning accuracy. Field plates rotate to follow apparent sky rotation. The spectrographs both analyze light from the 200 observing fibers each and back- illuminate the 400 fibers being re-positioned during the observing run. The 2dF fiber position and spectrograph system is a large and complex instrument located at the prime focus of the Anglo Australian Telescope. The mechanical design has departed somewhat from the earlier concepts of Gray et al, but still reflects the audacity of those first ideas. The positioner is capable of positioning 400 fibers on a field plate while another 400 fibers on another plate are observing at the focus of the telescope and feeding the twin spectrographs. When first proposed it must have seemed like ingenuity unfettered by caution. Yet now it works, and works wonderfully well. 2dF is a system which functions as the result of the combined and coordinated efforts of the astronomers, the mechanical designers and tradespeople, the electronic designers, the programmers, the support staff at the telescope, and the manufacturing subcontractors. The mechanical design of the 2dF positioner and spectrographs was carried out by the mechanical engineering staff of the AAO and the majority of the manufacture was carried out in the AAO workshops.

  2. DNA damage by reactive species: Mechanisms, mutation and repair.

    Science.gov (United States)

    Jena, N R

    2012-07-01

    DNA is continuously attacked by reactive species that can affect its structure and function severely. Structural modifications to DNA mainly arise from modifications in its bases that primarily occur due to their exposure to different reactive species. Apart from this, DNA strand break, inter- and intra-strand crosslinks and DNA-protein crosslinks can also affect the structure of DNA significantly. These structural modifications are involved in mutation, cancer and many other diseases. As it has the least oxidation potential among all the DNA bases, guanine is frequently attacked by reactive species, producing a plethora of lethal lesions. Fortunately, living cells are evolved with intelligent enzymes that continuously protect DNA from such damages. This review provides an overview of different guanine lesions formed due to reactions of guanine with different reactive species. Involvement of these lesions in inter- and intra-strand crosslinks, DNA-protein crosslinks and mutagenesis are discussed. How certain enzymes recognize and repair different guanine lesions in DNA are also presented.

  3. DNA damage by reactive species: Mechanisms, mutation and repair

    Indian Academy of Sciences (India)

    N R Jena

    2012-07-01

    DNA is continuously attacked by reactive species that can affect its structure and function severely. Structural modifications to DNA mainly arise from modifications in its bases that primarily occur due to their exposure to different reactive species. Apart from this, DNA strand break, inter- and intra-strand crosslinks and DNA–protein crosslinks can also affect the structure of DNA significantly. These structural modifications are involved in mutation, cancer and many other diseases. As it has the least oxidation potential among all the DNA bases, guanine is frequently attacked by reactive species, producing a plethora of lethal lesions. Fortunately, living cells are evolved with intelligent enzymes that continuously protect DNA from such damages. This review provides an overview of different guanine lesions formed due to reactions of guanine with different reactive species. Involvement of these lesions in inter- and intra-strand crosslinks, DNA–protein crosslinks and mutagenesis are discussed. How certain enzymes recognize and repair different guanine lesions in DNA are also presented.

  4. Cetuximab Induces Eme1-Mediated DNA Repair: a Novel Mechanism for Cetuximab Resistance

    Directory of Open Access Journals (Sweden)

    Agnieszka Weinandy

    2014-03-01

    Full Text Available Overexpression of the epidermal growth factor receptor (EGFR is observed in a large number of neoplasms. The monoclonal antibody cetuximab/Erbitux is frequently applied to treat EGFR-expressing tumors. However, the application of cetuximab alone or in combination with radio- and/or chemotherapy often yields only little benefit for patients. In the present study, we describe a mechanism that explains resistance of both tumor cell lines and cultured primary human glioma cells to cetuximab. Treatment of these cells with cetuximab promoted DNA synthesis in the absence of increased proliferation, suggesting that DNA repair pathways were activated. Indeed, we observed that cetuximab promoted the activation of the DNA damage response pathway and prevented the degradation of essential meiotic endonuclease 1 homolog 1 (Eme1, a heterodimeric endonuclease involved in DNA repair. The increased levels of Eme1 were necessary for enhanced DNA repair, and the knockdown of Eme1 was sufficient to prevent efficient DNA repair in response to ultraviolet-C light or megavoltage irradiation. These treatments reduced the survival of tumor cells, an effect that was reversed by cetuximab application. Again, this protection was dependent on Eme1. Taken together, these results suggest that cetuximab initiates pathways that result in the stabilization of Eme1, thereby resulting in enhanced DNA repair. Accordingly, cetuximab enhances DNA repair, reducing the effectiveness of DNA-damaging therapies. This aspect should be considered when using cetuximab as an antitumor agent and suggests that Eme1 is a negative predictive marker.

  5. Long-term anisotropic mechanical response of surgical meshes used to repair abdominal wall defects.

    Science.gov (United States)

    Hernández-Gascón, B; Peña, E; Pascual, G; Rodríguez, M; Bellón, J M; Calvo, B

    2012-01-01

    Routine hernia repair surgery involves the implant of synthetic mesh. However, this type of procedure may give rise to pain and bowel incarceration and strangulation, causing considerable patient disability. The purpose of this study was to compare the long-term behaviour of three commercial meshes used to repair the partially herniated abdomen in New Zealand White rabbits: the heavyweight (HW) mesh, Surgipro(®) and lightweight (LW) mesh, Optilene(®), both made of polypropylene (PP), and a mediumweight (MW) mesh, Infinit(®), made of polytetrafluoroethylene (PTFE). The implanted meshes were mechanical and histological assessed at 14, 90 and 180 days post-implant. This behaviour was compared to the anisotropic mechanical behaviour of the unrepaired abdominal wall in control non-operated rabbits. Both uniaxial mechanical tests conducted in craneo-caudal and perpendicular directions and histological findings revealed substantial collagen growth over the repaired hernial defects causing stiffness in the repair zone, and thus a change in the original properties of the meshes. The mechanical behaviour of the healthy tissue in the craneo-caudal direction was not reproduced by any of the implanted meshes after 14 days or 90 days of implant, whereas in the perpendicular direction, SUR and OPT achieved similar behaviour. From a mechanical standpoint, the anisotropic PP-lightweight meshes may be considered a good choice in the long run, which correlates with the structure of the regenerated tissue. Copyright © 2011 Elsevier Ltd. All rights reserved.

  6. Mechanical ventilation injury and repair in extremely and very preterm lungs.

    Directory of Open Access Journals (Sweden)

    Nadine Brew

    Full Text Available BACKGROUND: Extremely preterm infants often receive mechanical ventilation (MV, which can contribute to bronchopulmonary dysplasia (BPD. However, the effects of MV alone on the extremely preterm lung and the lung's capacity for repair are poorly understood. AIM: To characterise lung injury induced by MV alone, and mechanisms of injury and repair, in extremely preterm lungs and to compare them with very preterm lungs. METHODS: Extremely preterm lambs (0.75 of term were transiently exposed by hysterotomy and underwent 2 h of injurious MV. Lungs were collected 24 h and at 15 d after MV. Immunohistochemistry and morphometry were used to characterise injury and repair processes. qRT-PCR was performed on extremely and very preterm (0.85 of term lungs 24 h after MV to assess molecular injury and repair responses. RESULTS: 24 h after MV at 0.75 of term, lung parenchyma and bronchioles were severely injured; tissue space and myofibroblast density were increased, collagen and elastin fibres were deformed and secondary crest density was reduced. Bronchioles contained debris and their epithelium was injured and thickened. 24 h after MV at 0.75 and 0.85 of term, mRNA expression of potential mediators of lung repair were significantly increased. By 15 days after MV, most lung injury had resolved without treatment. CONCLUSIONS: Extremely immature lungs, particularly bronchioles, are severely injured by 2 h of MV. In the absence of continued ventilation these injured lungs are capable of repair. At 24 h after MV, genes associated with injurious MV are unaltered, while potential repair genes are activated in both extremely and very preterm lungs.

  7. DNA Repair and Photoprotection: Mechanisms of Overcoming Environmental Ultraviolet Radiation Exposure in Halophilic Archaea

    Directory of Open Access Journals (Sweden)

    Daniel L. Jones

    2017-09-01

    Full Text Available Halophilic archaea push the limits of life at several extremes. In particular, they are noted for their biochemical strategies in dealing with osmotic stress, low water activity and cycles of desiccation in their hypersaline environments. Another feature common to their habitats is intense ultraviolet (UV radiation, which is a challenge that microorganisms must overcome. The consequences of high UV exposure include DNA lesions arising directly from bond rearrangement of adjacent bipyrimidines, or indirectly from oxidative damage, which may ultimately result in mutation and cell death. As such, these microorganisms have evolved a number of strategies to navigate the threat of DNA damage, which we differentiate into two categories: DNA repair and photoprotection. Photoprotection encompasses damage avoidance strategies that serve as a “first line of defense,” and in halophilic archaea include pigmentation by carotenoids, mechanisms of oxidative damage avoidance, polyploidy, and genomic signatures that make DNA less susceptible to photodamage. Photolesions that do arise are addressed by a number of DNA repair mechanisms that halophilic archaea efficiently utilize, which include photoreactivation, nucleotide excision repair, base excision repair, and homologous recombination. This review seeks to place DNA damage, repair, and photoprotection in the context of halophilic archaea and the solar radiation of their hypersaline environments. We also provide new insight into the breadth of strategies and how they may work together to produce remarkable UV-resistance for these microorganisms.

  8. Engineering Mechanics and Design Applications Transdisciplinary Engineering Fundamentals

    CERN Document Server

    Ertas, Atila

    2011-01-01

    In the last decade, the number of complex problems facing engineers has increased, and the technical knowledge required to address and mitigate them continues to evolve rapidly. These problems include not only the design of engineering systems with numerous components and subsystems, but also the design, redesign, and interaction of social, political, managerial, commercial, biological, medical, and other systems. These systems are likely to be dynamic and adaptive in nature. Finding creative solutions to such large-scale, unstructured problems requires activities that cut across traditional d

  9. Mechanical Engineering Education and Its Challenges

    Science.gov (United States)

    Ow, C. S.; Kanan, M. M.

    2015-09-01

    The paper addresses historical development in Engineering Education in the country, its evolution till present day efforts toward the formation of Professional Engineers (PE). Of particular interest is the proposed recognition of more than one pathways towards PE Certification amongst member countries of the International Engineering Alliance (IEA). However, Engineering Education of Gen Y poses challenges at maintaining relevant benchmarks at the basic degree level. The widespread use of sophisticated software for simulation work in any undergraduate programme has its sacrifices with respect to emphasis on depth of knowledge. A definite mismatch between what is perceived by the educators and the actual performance of graduates had been identified in a forum and an employment survey conducted by the Institution of Engineers Malaysia (IEM). Suggestions as to how this can be addressed include the setting up of a Board of Educators to regulate the education industry.

  10. Repair of segmental bone defect using Totally Vitalized tissue engineered bone graft by a combined perfusion seeding and culture system.

    Directory of Open Access Journals (Sweden)

    Lin Wang

    Full Text Available BACKGROUND: The basic strategy to construct tissue engineered bone graft (TEBG is to combine osteoblastic cells with three dimensional (3D scaffold. Based on this strategy, we proposed the "Totally Vitalized TEBG" (TV-TEBG which was characterized by abundant and homogenously distributed cells with enhanced cell proliferation and differentiation and further investigated its biological performance in repairing segmental bone defect. METHODS: In this study, we constructed the TV-TEBG with the combination of customized flow perfusion seeding/culture system and β-tricalcium phosphate (β-TCP scaffold fabricated by Rapid Prototyping (RP technique. We systemically compared three kinds of TEBG constructed by perfusion seeding and perfusion culture (PSPC method, static seeding and perfusion culture (SSPC method, and static seeding and static culture (SSSC method for their in vitro performance and bone defect healing efficacy with a rabbit model. RESULTS: Our study has demonstrated that TEBG constructed by PSPC method exhibited better biological properties with higher daily D-glucose consumption, increased cell proliferation and differentiation, and better cell distribution, indicating the successful construction of TV-TEBG. After implanted into rabbit radius defects for 12 weeks, PSPC group exerted higher X-ray score close to autograft, much greater mechanical property evidenced by the biomechanical testing and significantly higher new bone formation as shown by histological analysis compared with the other two groups, and eventually obtained favorable healing efficacy of the segmental bone defect that was the closest to autograft transplantation. CONCLUSION: This study demonstrated the feasibility of TV-TEBG construction with combination of perfusion seeding, perfusion culture and RP technique which exerted excellent biological properties. The application of TV-TEBG may become a preferred candidate for segmental bone defect repair in orthopedic and

  11. Maintenance And Repair of Automotive Engine%汽车发动机的维护及保养

    Institute of Scientific and Technical Information of China (English)

    白有俊

    2014-01-01

    Correct and reasonable maintenance and repair of automotive engine is an important link to improve technical performance of the automobile, extend its life, reduce economic losses and ensure traffic safety. The article discusses in details how to have the reasonable and effective maintenance and repair for the automotive engine from the related engine knowledge.%正确合理地对汽车发动机进行维护和保养是提高汽车技术性能,延长其使用寿命,减少经济损失,保证行车安全的重要环节。文章从论述发动机相关知识等入手,对如何进行合理有效的汽车发动机维护和保养两个方面进行详细阐述。

  12. Case study. Health hazards of automotive repair mechanics: thermal and lighting comfort, particulate matter and noise.

    Science.gov (United States)

    Loupa, G

    2013-01-01

    An indoor environmental quality survey was conducted in a small private automotive repair shop during May 2009 (hot season) and February 2010 (cold season). It was established that the detached building, which is naturally ventilated and lit, had all the advantages of the temperate local climate. It provided a satisfactory microclimatic working environment, concerning the thermal and the lighting comfort, without excessive energy consumption for air-conditioning or lighting. Indoor number concentrations of particulate matter (PM) were monitored during both seasons. Their size distributions were strongly affected by the indoor activities and the air exchange rate of the building. During working hours, the average indoor/outdoor (I/O) number concentration ratio was 31 for PM0.3-1 in the hot season and 69 for the cold season. However I/O PM1-10 number concentration ratios were similar, 33 and 32 respectively, between the two seasons. The estimated indoor mass concentration of PM10 for the two seasons was on average 0.68 mg m(-3) and 1.19 mg m(-3), i.e., 22 and 36 times higher than outdoors, during the hot and the cold seasons, respectively. This is indicative that indoor air pollution may adversely affect mechanics' health. Noise levels were highly variable and the average LEX, 8 h of 69.3 dB(A) was below the European Union exposure limit value 87db (A). Noise originated from the use of manual hammers, the revving up of engines, and the closing of car doors or hoods. Octave band analysis indicated that the prevailing noise frequencies were in the area of the maximum ear sensitivity.

  13. Cellular mechanisms of neurovascular damage and repair after stroke.

    Science.gov (United States)

    Arai, Ken; Lok, Josephine; Guo, Shuzhen; Hayakawa, Kazuhide; Xing, Changhong; Lo, Eng H

    2011-09-01

    The biological processes underlying stroke are complex, and patients have a narrow repertoire of therapeutic opportunities. After the National Institutes of Health (NIH) convened the Stroke Progress Review Group in 2001, stroke research shifted from having a purely neurocentric focus to adopting a more integrated view wherein dynamic interactions between all cell types contribute to function and dysfunction in the brain. This so-called "neurovascular unit" provides a conceptual framework that emphasizes cell-cell interactions between neuronal, glial, and vascular elements. Under normal conditions, signaling within the neurovascular unit helps maintain homeostasis. After stroke, cell-cell signaling is disturbed, leading to pathophysiology. More recently, emerging data now suggest that these cell-cell signaling mechanisms may also mediate parallel processes of neurovascular remodeling during stroke recovery. Because plasticity is a signature feature of the young and developing brain, these concepts may have special relevance to how the pediatric brain responds after stroke.

  14. Statics formulas and problems : engineering mechanics 1

    CERN Document Server

    Gross, Dietmar; Wriggers, Peter; Schröder, Jörg; Müller, Ralf

    2017-01-01

    This book contains the most important formulas and more than 160 completely solved problems from Statics. It provides engineering students material to improve their skills and helps to gain experience in solving engineering problems. Particular emphasis is placed on finding the solution path and formulating the basic equations. Topics include: - Equilibrium - Center of Gravity, Center of Mass, Centroids - Support Reactions - Trusses - Beams, Frames, Arches - Cables - Work and Potential Energy - Static and Kinetic Friction - Moments of Inertia.

  15. Repairing peripheral nerve defects with tissue engineered artificial nerves in rats

    Institute of Scientific and Technical Information of China (English)

    WEI Ai-lin; LIU Shi-qing; TAO Hai-ying; PENG Hao

    2008-01-01

    Objective: To observe the effect of tissue engineered nerves in repairing peripheral nerve defects ( about 1. 5 cm in length) in rats to provide data for clinical application.Methods: Glycerinated sciatic nerves (2 cm in length) from 10 Sprague Dawley ( SD) rats ( aged 4 months) were used to prepare homologous dermal acellular matrix. Other 10 neonate SD rats (aged 5-7 days) were killed by neck dislocation. After removing the epineurium, the separated sciatic nerve tracts were cut into small pieces, then digested by 2.5 g/L trypsin and 625 U/ml collagenase and cultured in Dulbecco's modified Eagle's medium (DMEM) for 3 weeks. After proliferation, the Schwann cells ( SCs) were identified and prepared for use. And other 40 female adult SD rats (weighing 200 g and aged 3 months) with sciatic nerve defects of 1.5 cm in length were randomly divided into four groups: the defects of 10 rats bridged with proliferated SCs and homologous dermal acellular matrix (the tissue engineered nerve group, Group A), 10 rats with no SCs but homologous dermal acellular matrix with internal scaffolds ( Group B ), 10 with autologous nerves ( Group C) , and the other 10 with nothing (the blank control group, Group D). The general status of the rats was observed, the wet weight of triceps muscle of calf was monitored, and the histological observation of the regenerated nerves were made at 12 weeks after operation.Results: The wounds of all 40 rats healed after operation and no death was found. No foot ulceration was found in Groups A, B and C, but 7 rats suffered from foot ulceration in Group D. The triceps muscles of calf were depauperated in the experimental sides in all the groups compared with the uninjured sides,which was much more obvious in Group D. The wet weight of triceps muscle of calf and nerve electrophysiologic monitoring showed no statistical difference between Group A and Group C,but statistical difference was found between Groups A and B and Groups B and D. And significant

  16. Mechanical and materials engineering of modern structure and component design

    CERN Document Server

    Altenbach, Holm

    2015-01-01

    This book presents the latest findings on mechanical and materials engineering as applied to the design of modern engineering materials and components. The contributions cover the classical fields of mechanical, civil and materials engineering, as well as bioengineering and advanced materials processing and optimization. The materials and structures discussed can be categorized into modern steels, aluminium and titanium alloys, polymers/composite materials, biological and natural materials, material hybrids and modern nano-based materials. Analytical modelling, numerical simulation, state-of-the-art design tools and advanced experimental techniques are applied to characterize the materials’ performance and to design and optimize structures in different fields of engineering applications.

  17. Mechanical Testing of Hydrogels in Cartilage Tissue Engineering: Beyond the Compressive Modulus

    Science.gov (United States)

    Xiao, Yinghua; Friis, Elizabeth A.; Gehrke, Stevin H.

    2013-01-01

    Injuries to articular cartilage result in significant pain to patients and high medical costs. Unfortunately, cartilage repair strategies have been notoriously unreliable and/or complex. Biomaterial-based tissue-engineering strategies offer great promise, including the use of hydrogels to regenerate articular cartilage. Mechanical integrity is arguably the most important functional outcome of engineered cartilage, although mechanical testing of hydrogel-based constructs to date has focused primarily on deformation rather than failure properties. In addition to deformation testing, as the field of cartilage tissue engineering matures, this community will benefit from the addition of mechanical failure testing to outcome analyses, given the crucial clinical importance of the success of engineered constructs. However, there is a tremendous disparity in the methods used to evaluate mechanical failure of hydrogels and articular cartilage. In an effort to bridge the gap in mechanical testing methods of articular cartilage and hydrogels in cartilage regeneration, this review classifies the different toughness measurements for each. The urgency for identifying the common ground between these two disparate fields is high, as mechanical failure is ready to stand alongside stiffness as a functional design requirement. In comparing toughness measurement methods between hydrogels and cartilage, we recommend that the best option for evaluating mechanical failure of hydrogel-based constructs for cartilage tissue engineering may be tensile testing based on the single edge notch test, in part because specimen preparation is more straightforward and a related American Society for Testing and Materials (ASTM) standard can be adopted in a fracture mechanics context. PMID:23448091

  18. Dynamics formulas and problems : engineering mechanics 3

    CERN Document Server

    Gross, Dietmar; Wriggers, Peter; Schröder, Jörg; Müller, Ralf

    2017-01-01

    This book contains the most important formulas and more than 190 completely solved problems from Kinetics and Hydrodynamics. It provides engineering students material to improve their skills and helps to gain experience in solving engineering problems. Particular emphasis is placed on finding the solution path and formulating the basic equations. Topics include: - Kinematics of a Point - Kinetics of a Point Mass- Dynamics of a System of Point Masses - Kinematics of Rigid Bodies - Kinetics of Rigid Bodies - Impact - Vibrations - Non-Inertial Reference Frames - Hydrodynamics .

  19. UV-induced dark repair mechanisms in bacteria associated with drinking water.

    Science.gov (United States)

    Jungfer, Christina; Schwartz, Thomas; Obst, Ursula

    2007-01-01

    Caulobacter crescentus and Aquabacterium commune, both isolated from drinking water, as well as environmental isolates of Pseudomonas aeruginosa and Enterococcus faecium were treated with different UV fluences to study their capacity to restore induced DNA damages. Here, the induction of a key mechanism of bacterial dark repair, the so-called recA system, was analysed. With newly designed probes, the specific recA mRNA was detected by Northern blot. Additionally, the RecA protein was measured by the Western blot technique using a specific antibody. In drinking water bacteria as well as in opportunistic microorganisms, a specific induction of dark repair mechanisms was found even at UV fluences higher than 400J/m(2), the German standard for UV disinfection. This induction depended on the incubation time after UV treatment. Nevertheless, the UV-induced recA expressions were found to differ in the bacteria under investigation.

  20. The effects of multiple repairs on Inconel 718 weld mechanical properties

    Science.gov (United States)

    Russell, C. K.; Nunes, A. C., Jr.; Moore, D.

    1991-01-01

    Inconel 718 weldments were repaired 3, 6, 9, and 13 times using the gas tungsten arc welding process. The welded panels were machined into mechanical test specimens, postweld heat treated, and nondestructively tested. Tensile properties and high cycle fatigue life were evaluated and the results compared to unrepaired weld properties. Mechanical property data were analyzed using the statistical methods of difference in means for tensile properties and difference in log means and Weibull analysis for high cycle fatigue properties. Statistical analysis performed on the data did not show a significant decrease in tensile or high cycle fatigue properties due to the repeated repairs. Some degradation was observed in all properties, however, it was minimal.

  1. The cellular and molecular mechanisms of tissue repair and regeneration as revealed by studies in Xenopus

    Science.gov (United States)

    Li, Jingjing; Zhang, Siwei

    2016-01-01

    Abstract Survival of any living organism critically depends on its ability to repair and regenerate damaged tissues and/or organs during its lifetime following injury, disease, or aging. Various animal models from invertebrates to vertebrates have been used to investigate the molecular and cellular mechanisms of wound healing and tissue regeneration. It is hoped that such studies will form the framework for identifying novel clinical treatments that will improve the healing and regenerative capacity of humans. Amongst these models, Xenopus stands out as a particularly versatile and powerful system. This review summarizes recent findings using this model, which have provided fundamental knowledge of the mechanisms responsible for efficient and perfect tissue repair and regeneration.

  2. Understanding the Molecular Mechanism(s) of Formaldehyde-induced DNA-protein Crosslink Repair

    Science.gov (United States)

    Although formaldehyde has been shown to induce many kinds of DNA damage both in in vitro and in vivo assay systems, initial DNA-protein crosslink (DPC) formation might play a major role in FA-induced mutagenesis and carcinogenesis. Several DNA repair pathways, such as base excisi...

  3. Transplantation of genetically engineered cardiac fibroblasts producing recombinant human erythropoietin to repair the infarcted myocardium

    Directory of Open Access Journals (Sweden)

    Ruvinov Emil

    2008-11-01

    Full Text Available Abstract Background Erythropoietin possesses cellular protection properties. The aim of the present study was to test the hypothesis that in situ expression of recombinant human erythropoietin (rhEPO would improve tissue repair in rat after myocardial infarction (MI. Methods and results RhEPO-producing cardiac fibroblasts were generated ex vivo by transduction with retroviral vector. The anti-apoptotic effect of rhEPO-producing fibroblasts was evaluated by co-culture with rat neonatal cardiomyocytes exposed to H2O2-induced oxidative stress. Annexin V/PI assay and DAPI staining showed that compared with control, rhEPO forced expression markedly attenuated apoptosis and improved survival of cultured cardiomyocytes. To test the effect of rhEPO on the infarcted myocardium, Sprague-Dawley rats were subjected to permanent coronary artery occlusion, and rhEPO-producing fibroblasts, non-transduced fibroblasts, or saline, were injected into the scar tissue seven days after infarction. One month later, immunostaining identified rhEPO expression in the implanted engineered cells but not in controls. Compared with non-transduced fibroblasts or saline injection, implanted rhEPO-producing fibroblasts promoted vascularization in the scar, and prevented cell apoptosis. By two-dimensional echocardiography and postmortem morphometry, transplanted EPO-engineered fibroblasts did not prevent left ventricular (LV dysfunction and adverse LV remodeling 5 and 9 weeks after MI. Conclusion In situ expression of rhEPO enhances vascularization and reduces cell apoptosis in the infarcted myocardium. However, local EPO therapy is insufficient for functional improvement after MI in rat.

  4. Mathematical Building-Blocks in Engineering Mechanics

    Science.gov (United States)

    Boyajian, David M.

    2007-01-01

    A gamut of mathematical subjects and concepts are taught within a handful of courses formally required of the typical engineering student who so often questions the relevancy of being bound to certain lower-division prerequisites. Basic classes at the undergraduate level, in this context, include: Integral and Differential Calculus, Differential…

  5. Physicochemical Mechanism of Light-Driven DNA Repair by (6-4) Photolyases

    Science.gov (United States)

    Faraji, Shirin; Dreuw, Andreas

    2014-04-01

    DNA photolyases are light-activated enzymes that repair DNA damage induced by ultraviolet (UV) radiation. UV radiation causes two of the most abundant mutagenic and cytotoxic DNA lesions: cyclobutane pyrimidine dimers and 6-4 photolesions. Photolyases selectively bind to DNA and initiate the splitting of mutagenic pyrimidine dimers via photoinduced electron transfer from a flavin adenine dinucleotide anion (FADH-) to the lesion triggering its repair. This review discusses the consecutive steps of the repair process, from both experimental and theoretical points of view. It covers the following issues: the process of how photolyases accommodate the lesion into their binding pockets, excitation energy transfer between two involved catalytic cofactors, photoinduced electron transfer to the lesion, the splitting of the pyrimidine dimer radical anion, and the fate of the unstable radical species created after the splitting of the thymine dimer. In particular, mechanisms of the splitting and restoration of the original bases are described in detail, and the most probable repair pathways are outlined.

  6. 2012 International Conference on Mechanical and Electronic Engineering

    CERN Document Server

    Lin, Sally; ICMEE2012; Advances in Mechanical and Electronic Engineering v.2

    2012-01-01

    This book includes the volume 2 of the proceedings of the 2012 International Conference on Mechanical and Electronic Engineering(ICMEE2012), held at June 23-24,2012 in Hefei, China. The conference provided a rare opportunity to bring together worldwide researchers who are working in the fields. This volume 2 is focusing on Mechatronic Engineering and Technology,  Electronic Engineering and Electronic Information Technology .

  7. Neurobehavioral and respiratory findings in jet engine repair workers: A comparison of exposed and unexposed volunteers.

    Science.gov (United States)

    Kilburn, K H

    1999-04-01

    Workers repairing jet engines had respiratory, rheumatic, and neurobehavioral symptoms. They had welded and ground stainless steel parts using hard metal tools and cleaned metal with chlorinated and fluorinated organic solvents. We compared 154 workers and 112 unexposed subjects, all volunteers of similar ages and with similar educational levels, for abnormalities on chest radiographs, spirometric measurements, and questionnaires. Also appraised were performance of reaction time, balance, blink reflex latency, color discrimination, Culture Fair, vocabulary, slotted pegboard, trail making A and B, profile of mood states (POMS), and frequencies of 35 symptoms. Compared to unexposed subjects, workers had significantly more respiratory symptoms but no differences in pulmonary function. They had significantly prolonged simple and choice reaction time (P<0.0001), and abnormal balance with eyes open and eyes closed (P<0. 0001), and abnormal color discrimination. Blink reflex latency was abnormal in both exposed workers and in local unexposed compared to other reference groups. Focus of the inquiry on lung disease helped ensure that for neurobehavioral tests confounding factors were minimal and known biases were small. We tentatively attribute the neurobehavioral impairments and increased symptom frequencies to chlorinated solvent exposure. Excessive respiratory symptoms are attributed to welding stainless steel combined with cigarette smoking. Specifically, manganese exposure may have affected the respiratory and the central nervous systems.

  8. Validation of the Algorithms for Depot Exchangeable Repair and Modification Costs for NSNS and Engines for the Component Support Cost System (D160B).

    Science.gov (United States)

    2014-09-26

    IDENTIFICATION OI 03 NOMENCLATURE . ITEM 012 03 PRICE. STANDARD INVENTORY 013 03 CODE. WEAPON SYSTEM SUPPORT 014 06 CODE. WEAPON SYSTEM SUPPORT. POSITIONS I TO...calculation of standard depot repair prices ( sales prices). Various knowledgeable Air Force personnel have noted that it is not unusual for an engine to be both...cost elements not used in calculation of standard depot repair prices (" sales prices"). ISI affirms the congruence of the definitions of repair prices as

  9. Robot based three-dimensional welding for jet engine blade repair and rapid prototyping of small components

    Science.gov (United States)

    Thukaram, Santosh Kumar

    Aero engines are made up of a large number of blades which are subject to wear and damage. They are expensive and must be repaired wherever possible. Engines also have small components which are required in small numbers that need to be developed rapidly. The first part of this research work focuses on developing a robust automated blade repair method using robotic welding. Optimal weld parameters were developed for build-up of edges having different thicknesses. Samples with varying Current and varying travel speed were produced and their micro hardness values were compared. Blade profiles were welded upon. The second part involves a methodology for producing small components using rapid prototyping (RP) techniques. This part involves use of 3D robotic welding for layered manufacturing. Tensile samples produced using the metal RP method were tested and results were found to be well above the minimum cast specifications for the given material.

  10. Formula Student as Part of a Mechanical Engineering Curriculum

    Science.gov (United States)

    Davies, Huw Charles

    2013-01-01

    Formula Student (FS) is a multi-university student design competition managed by the UK Institution of Mechanical Engineers. Students are required to demonstrate and prove their creativity and engineering skills through the design, manufacture and financing of a small formula style race car. This paper seeks to explore the educational value that…

  11. Formula Student as Part of a Mechanical Engineering Curriculum

    Science.gov (United States)

    Davies, Huw Charles

    2013-01-01

    Formula Student (FS) is a multi-university student design competition managed by the UK Institution of Mechanical Engineers. Students are required to demonstrate and prove their creativity and engineering skills through the design, manufacture and financing of a small formula style race car. This paper seeks to explore the educational value that…

  12. Mechanical and toughness properties of robotic-FSW repair welds in 6061-T6 aluminium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Brinckmann, S.; Strombeck, A. v.; Schilling, C.; Santos, J.F. dos; Kocak, M. [GKSS-Forschungszentrum Geesthacht GmbH (Germany). Inst. fuer Materialforschung; Lohwasser, D. [DaimlerChrysler Aerospace Airbus GmbH, Bremen (Germany)

    2000-07-01

    Panel or structures welded in fixed installations might require local repair of eventual process induced defects. Ideally such repair operations should take place outside the production line to avoid interruption of the manufacturing flow. Robotic FSW systems offer the required flexibility to perform such repairs. The main objective of this work was to conduct a preliminary investigation on the microstructural, mechanical and toughness properties of robotic friction stir repair welds. To achieve this objective defective welds have been purposely produced and subsequently repaired. Specimens for microstructural analysis, mechanical and fracture toughness testing have been obtained from repaired and defect-free welds as well as from the base plate for comparison purposes. The mechanical properties have been established using standard tests, i.e. hardness, bending and tensile. Toughness properties of the joints have been determined using small (compact tension - CT) and large (M(T)) scale specimens. Fatigue pre-cracks were positioned in the nugget and HAZ. Crack resistance curves (R-Curves) were determined using the potential drop technique. The obtained results indicated that the additional thermal cycle and deformation process imposed by the repair weld did not adversely affect the mechanical and toughness properties of the nugget area. Both defect-free and repair welds showed higher toughness than the base material. Pre-cracks positioned in the nugget region were deviated into the lower strength TMAZ after initiation and ductile crack growth within the nugget area due to strength undermatch. Later propagation remained within the TMAZ. (orig.) [German] Das Schweissen von Elementen oder Strukturen kann eine lokale Reparatur erfordern, wenn durch den Fuegeprozess ausgeloeste Fehler auftreten. Vorteilhafterweise sollten die Reparaturen ausserhalb der Fertigungslinie erfolgen, um den Produktionsablauf nicht zu stoeren. Robotergestuetzte FSW-Systeme bieten die benoetigte

  13. Quantum mechanics/molecular mechanics study on the oxygen binding and substrate hydroxylation step in AlkB repair enzymes.

    Science.gov (United States)

    Quesne, Matthew G; Latifi, Reza; Gonzalez-Ovalle, Luis E; Kumar, Devesh; de Visser, Sam P

    2014-01-07

    AlkB repair enzymes are important nonheme iron enzymes that catalyse the demethylation of alkylated DNA bases in humans, which is a vital reaction in the body that heals externally damaged DNA bases. Its mechanism is currently controversial and in order to resolve the catalytic mechanism of these enzymes, a quantum mechanics/molecular mechanics (QM/MM) study was performed on the demethylation of the N(1) -methyladenine fragment by AlkB repair enzymes. Firstly, the initial modelling identified the oxygen binding site of the enzyme. Secondly, the oxygen activation mechanism was investigated and a novel pathway was found, whereby the catalytically active iron(IV)-oxo intermediate in the catalytic cycle undergoes an initial isomerisation assisted by an Arg residue in the substrate binding pocket, which then brings the oxo group in close contact with the methyl group of the alkylated DNA base. This enables a subsequent rate-determining hydrogen-atom abstraction on competitive σ- and π-pathways on a quintet spin-state surface. These findings give evidence of different locations of the oxygen and substrate binding channels in the enzyme and the origin of the separation of the oxygen-bound intermediates in the catalytic cycle from substrate. Our studies are compared with small model complexes and the effect of protein and environment on the kinetics and mechanism is explained.

  14. Gelatin Scaffolds with Controlled Pore Structure and Mechanical Property for Cartilage Tissue Engineering.

    Science.gov (United States)

    Chen, Shangwu; Zhang, Qin; Nakamoto, Tomoko; Kawazoe, Naoki; Chen, Guoping

    2016-03-01

    Engineering of cartilage tissue in vitro using porous scaffolds and chondrocytes provides a promising approach for cartilage repair. However, nonuniform cell distribution and heterogeneous tissue formation together with weak mechanical property of in vitro engineered cartilage limit their clinical application. In this study, gelatin porous scaffolds with homogeneous and open pores were prepared using ice particulates and freeze-drying. The scaffolds were used to culture bovine articular chondrocytes to engineer cartilage tissue in vitro. The pore structure and mechanical property of gelatin scaffolds could be well controlled by using different ratios of ice particulates to gelatin solution and different concentrations of gelatin. Gelatin scaffolds prepared from ≥70% ice particulates enabled homogeneous seeding of bovine articular chondrocytes throughout the scaffolds and formation of homogeneous cartilage extracellular matrix. While soft scaffolds underwent cellular contraction, stiff scaffolds resisted cellular contraction and had significantly higher cell proliferation and synthesis of sulfated glycosaminoglycan. Compared with the gelatin scaffolds prepared without ice particulates, the gelatin scaffolds prepared with ice particulates facilitated formation of homogeneous cartilage tissue with significantly higher compressive modulus. The gelatin scaffolds with highly open pore structure and good mechanical property can be used to improve in vitro tissue-engineered cartilage.

  15. Replace the Carburetor Diaphragm. Pulsa-Jet Style with Automatic Choke. Fuel System. Student Manual 2. Small Engine Repair Series. First Edition.

    Science.gov (United States)

    Hill, Pamela

    This student manual, part of a small-engine repair series on servicing fuel systems, is designed for use by special needs students in Texas. The manual explains in pictures and short sentences, written on a low reading level, the job of replacing carburetor diaphragms. Along with the steps of this repair job, specific safety and caution…

  16. DNA repair pathways underlie a common genetic mechanism modulating onset in polyglutamine diseases

    Science.gov (United States)

    Bettencourt, Conceição; Hensman‐Moss, Davina; Flower, Michael; Wiethoff, Sarah; Brice, Alexis; Goizet, Cyril; Stevanin, Giovanni; Koutsis, Georgios; Karadima, Georgia; Panas, Marios; Yescas‐Gómez, Petra; García‐Velázquez, Lizbeth Esmeralda; Alonso‐Vilatela, María Elisa; Lima, Manuela; Raposo, Mafalda; Traynor, Bryan; Sweeney, Mary; Wood, Nicholas; Giunti, Paola; Durr, Alexandra; Holmans, Peter; Houlden, Henry; Tabrizi, Sarah J.

    2016-01-01

    Objective The polyglutamine diseases, including Huntington's disease (HD) and multiple spinocerebellar ataxias (SCAs), are among the commonest hereditary neurodegenerative diseases. They are caused by expanded CAG tracts, encoding glutamine, in different genes. Longer CAG repeat tracts are associated with earlier ages at onset, but this does not account for all of the difference, and the existence of additional genetic modifying factors has been suggested in these diseases. A recent genome‐wide association study (GWAS) in HD found association between age at onset and genetic variants in DNA repair pathways, and we therefore tested whether the modifying effects of variants in DNA repair genes have wider effects in the polyglutamine diseases. Methods We assembled an independent cohort of 1,462 subjects with HD and polyglutamine SCAs, and genotyped single‐nucleotide polymorphisms (SNPs) selected from the most significant hits in the HD study. Results In the analysis of DNA repair genes as a group, we found the most significant association with age at onset when grouping all polyglutamine diseases (HD+SCAs; p = 1.43 × 10–5). In individual SNP analysis, we found significant associations for rs3512 in FAN1 with HD+SCAs (p = 1.52 × 10–5) and all SCAs (p = 2.22 × 10–4) and rs1805323 in PMS2 with HD+SCAs (p = 3.14 × 10–5), all in the same direction as in the HD GWAS. Interpretation We show that DNA repair genes significantly modify age at onset in HD and SCAs, suggesting a common pathogenic mechanism, which could operate through the observed somatic expansion of repeats that can be modulated by genetic manipulation of DNA repair in disease models. This offers novel therapeutic opportunities in multiple diseases. Ann Neurol 2016;79:983–990 PMID:27044000

  17. Alternative mechanisms of telomere lengthening: Permissive mutations, DNA repair proteins and tumorigenic progression

    Energy Technology Data Exchange (ETDEWEB)

    Gocha, April Renee Sandy; Harris, Julia [Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University College of Medicine, Columbus, OH 43210 (United States); Groden, Joanna, E-mail: joanna.groden@osumc.edu [Department of Molecular Virology, Immunology and Medical Genetics, The Ohio State University College of Medicine, Columbus, OH 43210 (United States)

    2013-03-15

    Highlights: ► Neoplastic cells maintain telomeres by telomerase or ALT. ► Genetic mutations in p53, ATRX, DAXX or H3F3A may activate ALT. ► Many DNA repair proteins are involved in ALT. ► Tumor progression is favored by telomerase expression. - Abstract: Telomeres protect chromosome termini to maintain genomic stability and regulate cellular lifespan. Maintenance of telomere length is required for neoplastic cells after the acquisition of mutations that deregulate cell cycle control and increase cellular proliferation, and can occur through expression of the enzyme telomerase or in a telomerase-independent manner termed alternative lengthening of telomeres (ALT). The precise mechanisms that govern the activation of ALT or telomerase in tumor cells are unknown, although cellular origin may favor one or the other mechanisms. ALT pathways are incompletely understood to date; however, recent publications have increasingly broadened our understanding of how ALT is activated, how it proceeds, and how it influences tumor growth. Specific mutational events influence ALT activation, as mutations in genes that suppress recombination and/or alterations in the regulation of telomerase expression are associated with ALT. Once engaged, ALT uses DNA repair proteins to maintain telomeres in the absence of telomerase; experiments that manipulate the expression of specific proteins in cells using ALT are illuminating some of its mechanisms. Furthermore, ALT may influence tumor growth, as experimental and clinical data suggest that telomerase expression may favor tumor progression. This review summarizes recent findings in mammalian cells and models, as well as clinical data, that identify the genetic mutations permissive to ALT, the DNA repair proteins involved in ALT mechanisms and the importance of telomere maintenance mechanisms for tumor progression. A comprehensive understanding of the mechanisms that permit tumor cell immortalization will be important for identifying

  18. Quarterly Bulletin of the Division of Mechanical Engineering and the National Aeronautical Establishment, 1 October to 31 December 1975.

    Science.gov (United States)

    AERONAUTICS, * MECHANICAL ENGINEERING , SHIPS, CONTROL SYSTEMS, AIRCRAFT, CANADA, HUMAN FACTORS ENGINEERING, GAS DYNAMICS, MECHANICS, FUELS, ENGINES, MARINE ENGINEERING, HYDRODYNAMICS, HARBORS, AERODYNAMICS, FLIGHT RECORDERS.

  19. Mechanical Complication with Broviac Repair Kit in a 4-Year-Old Boy with MEN 2a

    Directory of Open Access Journals (Sweden)

    Sergio B. Sesia

    2009-01-01

    Full Text Available Background. Mechanical complications in the use of indwelling central venous catheters (CVCs such as the Broviac catheter (BC include kinking, occlusion, dislocation or leaking. We report on a mechanical complication after using a repair kit for the BC. Method. A 4-year old boy, suffering from multiple endocrine neoplasia type 2a (MEN 2a, intestinal aganglionosis (Hirschsprung's disease, and short bowel syndrome, required a BC for home parenteral nutrition. Result. Due to recurrent leakage of the BC, 5 subsequent repairs were necessary within seven months. During one repair a metallic tube belonging to the repair kit was found to have migrated proximally to the skin entrance level within the BC and requiring surgical removal. Conclusion. To our knowledge, this is the first report focusing on such a serious complication using a BC and its repair kit. The proximal migration of this metallic tube constitutes a distinct theoretical risk of endothoracic foreign body embolization.

  20. Mechanical behaviour of engineering materials. Metals, ceramics, polymers, and composites

    Energy Technology Data Exchange (ETDEWEB)

    Roesler, Joachim; Baeker, Martin [TU Braunschweig (Germany). Inst. fuer Werkstoffe; Harders, Harald

    2007-07-01

    How do engineering materials deform when bearing mechanical loads? To answer this crucial question, the book bridges the gap between continuum mechanics and materials science. The different kinds of material deformation (elasticity, plasticity, fracture, creep, fatigue) are explained in detail. The book also discusses the physical processes occurring during the deformation of all classes of engineering materials (metals, ceramics, polymers, and composites) and shows how these materials can be strengthened to meet the design requirements. It provides the knowledge needed in selecting the appropriate engineering material for a certain design problem.

  1. Latest progress of soft rock mechanics and engineering in China

    Directory of Open Access Journals (Sweden)

    Manchao He

    2014-06-01

    Full Text Available The progress of soft rock mechanics and associated technology in China is basically accompanied by the development of mining engineering and the increasing disasters of large rock deformation during construction of underground engineering. In this regard, Chinese scholars proposed various concepts and classification methods for soft rocks in terms of engineering practices. The large deformation mechanism of engineering soft rocks is to be understood through numerous experiments; and thus a coupled support theory for soft rock roadways is established, followed by the development of a new support material, i.e. the constant resistance and large deformation bolt/anchor with negative Poisson's ratio effect, and associated control technology. Field results show that large deformation problems related to numbers of engineering cases can be well addressed with this new technology, an effective way for similar soft rock deformation control.

  2. Latest progress of soft rock mechanics and engineering in China

    Institute of Scientific and Technical Information of China (English)

    Manchao He

    2014-01-01

    The progress of soft rock mechanics and associated technology in China is basically accompanied by the development of mining engineering and the increasing disasters of large rock deformation during construction of underground engineering. In this regard, Chinese scholars proposed various concepts and classification methods for soft rocks in terms of engineering practices. The large deformation mechanism of engineering soft rocks is to be understood through numerous experiments; and thus a coupled support theory for soft rock roadways is established, followed by the development of a new support material, i.e. the constant resistance and large deformation bolt/anchor with negative Poisson’s ratio effect, and associated control technology. Field results show that large deformation problems related to numbers of engineering cases can be well addressed with this new technology, an effective way for similar soft rock deformation control.

  3. Making objective decisions in mechanical engineering problems

    Science.gov (United States)

    Raicu, A.; Oanta, E.; Sabau, A.

    2017-08-01

    Decision making process has a great influence in the development of a given project, the goal being to select an optimal choice in a given context. Because of its great importance, the decision making was studied using various science methods, finally being conceived the game theory that is considered the background for the science of logical decision making in various fields. The paper presents some basic ideas regarding the game theory in order to offer the necessary information to understand the multiple-criteria decision making (MCDM) problems in engineering. The solution is to transform the multiple-criteria problem in a one-criterion decision problem, using the notion of utility, together with the weighting sum model or the weighting product model. The weighted importance of the criteria is computed using the so-called Step method applied to a relation of preferences between the criteria. Two relevant examples from engineering are also presented. The future directions of research consist of the use of other types of criteria, the development of computer based instruments for decision making general problems and to conceive a software module based on expert system principles to be included in the Wiki software applications for polymeric materials that are already operational.

  4. Advances in Application of Mechanical Stimuli in Bioreactors for Cartilage Tissue Engineering.

    Science.gov (United States)

    Li, Ke; Zhang, Chunqiu; Qiu, Lulu; Gao, Lilan; Zhang, Xizheng

    2017-08-01

    Articular cartilage (AC) is the weight-bearing tissue in diarthroses. It lacks the capacity for self-healing once there are injuries or diseases due to its avascularity. With the development of tissue engineering, repairing cartilage defects through transplantation of engineered cartilage that closely matches properties of native cartilage has become a new option for curing cartilage diseases. The main hurdle for clinical application of engineered cartilage is how to develop functional cartilage constructs for mass production in a credible way. Recently, impressive hyaline cartilage that may have the potential to provide capabilities for treating large cartilage lesions in the future has been produced in laboratories. The key to functional cartilage construction in vitro is to identify appropriate mechanical stimuli. First, they should ensure the function of metabolism because mechanical stimuli play the role of blood vessels in the metabolism of AC, for example, acquiring nutrition and removing wastes. Second, they should mimic the movement of synovial joints and produce phenotypically correct tissues to achieve the adaptive development between the micro- and macrostructure and function. In this article, we divide mechanical stimuli into three types according to forces transmitted by different media in bioreactors, namely forces transmitted through the liquid medium, solid medium, or other media, then we review and summarize the research status of bioreactors for cartilage tissue engineering (CTE), mainly focusing on the effects of diverse mechanical stimuli on engineered cartilage. Based on current researches, there are several motion patterns in knee joints; but compression, tension, shear, fluid shear, or hydrostatic pressure each only partially reflects the mechanical condition in vivo. In this study, we propose that rolling-sliding-compression load consists of various stimuli that will represent better mechanical environment in CTE. In addition, engineers

  5. Engineering a General Education Program: Designing Mechanical Engineering General Education Courses

    Science.gov (United States)

    Fagette, Paul; Chen, Shih-Jiun; Baran, George R.; Samuel, Solomon P.; Kiani, Mohammad F.

    2013-01-01

    The Department of Mechanical Engineering at our institution created two engineering courses for the General Education Program that count towards second level general science credit (traditional science courses are first level). The courses were designed for the general student population based upon the requirements of our General Education Program…

  6. Deconstructing Engineering Education Programmes: The DEEP Project to Reform the Mechanical Engineering Curriculum

    Science.gov (United States)

    Busch-Vishniac, Ilene; Kibler, Tom; Campbell, Patricia B.; Patterson, Eann; Guillaume, Darrell; Jarosz, Jeffrey; Chassapis, Constantin; Emery, Ashley; Ellis, Glenn; Whitworth, Horace; Metz, Susan; Brainard, Suzanne; Ray, Pradosh

    2011-01-01

    The goal of the Deconstructing Engineering Education Programmes project is to revise the mechanical engineering undergraduate curriculum to make the discipline more able to attract and retain a diverse community of students. The project seeks to reduce and reorder the prerequisite structure linking courses to offer greater flexibility for…

  7. Control Engineering as a Part of Undergraduate Curriculum for Mechanical Engineering in India

    Science.gov (United States)

    Akhtar, Shagil; Iqbal, Syed Muneeb; Bajpai, Shrish

    2016-01-01

    In this present study we have traced the genesis of control engineering in the scope of mechanical engineering and then some analysis on its recent developments, their increasing need and how this particular subject has evolved machines functioning nowadays specifically its standard of education in India. We have probed this field right from its…

  8. Deconstructing Engineering Education Programmes: The DEEP Project to Reform the Mechanical Engineering Curriculum

    Science.gov (United States)

    Busch-Vishniac, Ilene; Kibler, Tom; Campbell, Patricia B.; Patterson, Eann; Guillaume, Darrell; Jarosz, Jeffrey; Chassapis, Constantin; Emery, Ashley; Ellis, Glenn; Whitworth, Horace; Metz, Susan; Brainard, Suzanne; Ray, Pradosh

    2011-01-01

    The goal of the Deconstructing Engineering Education Programmes project is to revise the mechanical engineering undergraduate curriculum to make the discipline more able to attract and retain a diverse community of students. The project seeks to reduce and reorder the prerequisite structure linking courses to offer greater flexibility for…

  9. Engineering a General Education Program: Designing Mechanical Engineering General Education Courses

    Science.gov (United States)

    Fagette, Paul; Chen, Shih-Jiun; Baran, George R.; Samuel, Solomon P.; Kiani, Mohammad F.

    2013-01-01

    The Department of Mechanical Engineering at our institution created two engineering courses for the General Education Program that count towards second level general science credit (traditional science courses are first level). The courses were designed for the general student population based upon the requirements of our General Education Program…

  10. Control Engineering as a Part of Undergraduate Curriculum for Mechanical Engineering in India

    Science.gov (United States)

    Akhtar, Shagil; Iqbal, Syed Muneeb; Bajpai, Shrish

    2016-01-01

    In this present study we have traced the genesis of control engineering in the scope of mechanical engineering and then some analysis on its recent developments, their increasing need and how this particular subject has evolved machines functioning nowadays specifically its standard of education in India. We have probed this field right from its…

  11. System dynamics an introduction for mechanical engineers

    CERN Document Server

    Seeler, Karl A

    2014-01-01

    This essential textbook takes the student from the initial steps in modeling a dynamic system through development of the mathematical models needed for feedback control.  The generously-illustrated, student-friendly text focuses on fundamental theoretical development rather than the application of commercial software.  Practical details of machine design are included to motivate the non-mathematically inclined student. This book also: Emphasizes the linear graph method for modeling dynamic systems Offers a systematic approach for creating an engineering model, extracting information, and formulating mathematical analyses Adopts a unifying theme of power flow as the dynamic agent that eases analysis of hybrid systems, such as machinery Presents differential equations as dynamic operators and stresses input/output relationships Introduces Mathcad and programming in MATLAB Allows for use of Open Source Computational Software (R or C) Features over 1000 illustrations

  12. The structural and mechanical properties of the Achilles tendon 2 years after surgical repair.

    Science.gov (United States)

    Geremia, Jeam Marcel; Bobbert, Maarten Frank; Casa Nova, Mayra; Ott, Rafael Duvelius; Lemos, Fernando de Aguiar; Lupion, Raquel de Oliveira; Frasson, Viviane Bortoluzzi; Vaz, Marco Aurélio

    2015-06-01

    Acute ruptures of the Achilles tendon affect the tendon's structural and mechanical properties. The long-term effects of surgical repair on these properties remain unclear. To evaluate effects of early mobilization versus traditional immobilization rehabilitation programs 2 years after surgical Achilles tendon repair, by comparing force-elongation and stress-strain relationships of the injured tendon to those of the uninjured tendon. A group of males with previous Achilles tendon rupture (n=18) and a group of healthy male controls (n=9) participated. Achilles tendon rupture group consisted of patients that had received early mobilization (n=9) and patients that had received traditional immobilization with a plaster cast (n=9). Comparisons of tendon structural and mechanical properties were made between Achilles tendon rupture and healthy control groups, and between the uninjured and injured sides of the two rehabilitation groups in Achilles tendon rupture group. Ultrasound was used to determine bilaterally tendon cross-sectional area, tendon resting length, and tendon elongation as a function of torque during maximal voluntary plantar flexion. From these data, Achilles tendon force-elongation and stress-strain relationships were determined. The Achilles tendon rupture group uninjured side was not different from healthy control group. Structural and mechanical parameters of the injured side were not different between the Achilles tendon rupture early mobilization and the immobilization groups. Compared to the uninjured side, the injured side showed a reduction in stress at maximal voluntary force, in Young's modulus and in stiffness. Two years post-surgical repair, the Achilles tendon mechanical properties had not returned to the uninjured contralateral tendon values. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Nano surface engineering and remanufacture engineering

    Institute of Scientific and Technical Information of China (English)

    XU Bin-shi

    2004-01-01

    Nano surface engineering and remanufacture engineering are introduced, and the relationship between them is set forth. It points out the superiority of nano surface engineering to the traditional one, and reveals the advantages of remanufacture engineering. Taking some nano surface techniques as samples, such as nano-materials brush electroplating, nano-materials thermal spraying and nano-materials self-repairing antifriction additive technology, it shows the applications of nano surface engineering technology to remanufacturing mechanical parts.

  14. Mathematical concepts for mechanical engineering design

    CERN Document Server

    Asli, Kaveh Hariri; Aliyev, Soltan Ali Ogli

    2013-01-01

    PrefaceIntroductionHeat Flow: From Theory to PracticeDispersed Fluid and Ideal Fluid MechanicsModeling for Pressure Wave into Water PipelineHeat Transfer and Vapor BubbleMathematical Concepts and Computational Approaches on Hydrodynamics InstabilityMathematical Concepts and Dynamic ModelingModeling for Predictions of Air Entrance into Water PipelineIndex

  15. Control Engineering Analysis of Mechanical Pitch Systems

    Science.gov (United States)

    Bernicke, Olaf; Gauterin, Eckhard; Schulte, Horst; Zajac, Michal

    2014-12-01

    With the help of a local stability analysis the coefficient range of a discrete damper, used for centrifugal forced, mechanical pitch system of small wind turbines (SWT), is gained for equilibrium points. - By a global stability analysis the gained coefficient range can be validated. An appropriate approach by Takagi-Sugeno is presented in the paper.

  16. Repair mechanisms inducible to the DNA in I.M.M.S. biological systems; Mecanismos de reparacion inducible del ADN en sistemas biologicos I.M.M.S

    Energy Technology Data Exchange (ETDEWEB)

    Guzman, J.; Arceo, C.; Cortinas, C.; Rosa, M.E. De la; Olvera, O.; Cruces, M.; Pimentel, E

    1990-03-15

    Given the characteristics of the MMS and the relative antecedents to the repair mechanisms in eucariontes are sought to determine the effect of the MMS on the genetic material and their repair in Drosophila melanogaster. (Author)

  17. Sp1 facilitates DNA double-strand break repair through a nontranscriptional mechanism.

    Science.gov (United States)

    Beishline, Kate; Kelly, Crystal M; Olofsson, Beatrix A; Koduri, Sravanthi; Emrich, Jacqueline; Greenberg, Roger A; Azizkhan-Clifford, Jane

    2012-09-01

    Sp1 is a ubiquitously expressed transcription factor that is phosphorylated by ataxia telangiectasia mutated kinase (ATM) in response to ionizing radiation and H(2)O(2). Here, we show by indirect immunofluorescence that Sp1 phosphorylated on serine 101 (pSp1) localizes to ionizing radiation-induced foci with phosphorylated histone variant γH2Ax and members of the MRN (Mre11, Rad50, and Nbs1) complex. More precise analysis of occupancy of DNA double-strand breaks (DSBs) by chromatin immunoprecipitation (ChIP) shows that Sp1, like Nbs1, resides within 200 bp of DSBs. Using laser microirradiation of cells, we demonstrate that pSp1 is present at DNA DSBs by 7.5 min after induction of damage and remains at the break site for at least 8 h. Depletion of Sp1 inhibits repair of site-specific DNA breaks, and the N-terminal 182-amino-acid peptide, which contains targets of ATM kinase but lacks the zinc finger DNA binding domain, is phosphorylated, localizes to DSBs, and rescues the repair defect resulting from Sp1 depletion. Together, these data demonstrate that Sp1 is rapidly recruited to the region immediately adjacent to sites of DNA DSBs and is required for DSB repair, through a mechanism independent of its sequence-directed transcriptional effects.

  18. Allogeneic versus autologous derived cell sources for use in engineered bone-ligament-bone grafts in sheep anterior cruciate ligament repair.

    Science.gov (United States)

    Mahalingam, Vasudevan D; Behbahani-Nejad, Nilofar; Horine, Storm V; Olsen, Tyler J; Smietana, Michael J; Wojtys, Edward M; Wellik, Deneen M; Arruda, Ellen M; Larkin, Lisa M

    2015-03-01

    The use of autografts versus allografts for anterior cruciate ligament (ACL) reconstruction is controversial. The current popular options for ACL reconstruction are patellar tendon or hamstring autografts, yet advances in allograft technologies have made allogeneic grafts a favorable option for repair tissue. Despite this, the mismatched biomechanical properties and risk of osteoarthritis resulting from the current graft technologies have prompted the investigation of new tissue sources for ACL reconstruction. Previous work by our lab has demonstrated that tissue-engineered bone-ligament-bone (BLB) constructs generated from an allogeneic cell source develop structural and functional properties similar to those of native ACL and vascular and neural structures that exceed those of autologous patellar tendon grafts. In this study, we investigated the effectiveness of our tissue-engineered ligament constructs fabricated from autologous versus allogeneic cell sources. Our preliminary results demonstrate that 6 months postimplantation, our tissue-engineered auto- and allogeneic BLB grafts show similar histological and mechanical outcomes indicating that the autologous grafts are a viable option for ACL reconstruction. These data indicate that our tissue-engineered autologous ligament graft could be used in clinical situations where immune rejection and disease transmission may preclude allograft use.

  19. Mesenchymal stem cells delivered in a microsphere-based engineered skin contribute to cutaneous wound healing and sweat gland repair.

    Science.gov (United States)

    Huang, Sha; Lu, Gang; Wu, Yan; Jirigala, Enhe; Xu, Yongan; Ma, Kui; Fu, Xiaobing

    2012-04-01

    Bone-marrow-derived mesenchymal stem cells (BM-MSCs) can contribute to wound healing after skin injury. However, the role of BM-MSCs on repairing skin appendages in renewal tissues is incompletely explored. Moreover, most preclinical studies suggest that the therapeutic effects afforded by BM-MSCs transplantation are short-lived and relatively unstable. To assess whether engrafted bone-marrow-derived mesenchymal stem cells via a delivery system can participate in cutaneous wound healing and sweat-gland repair in mice. For safe and effective delivery of BM-MSCs to wounds, epidermal growth factor (EGF) microspheres were firstly developed to both support cells and maintain appropriate stimuli, then cell-seeded microspheres were incorporated with biomimetic scaffolds and thus fabricated an engineered skin construct with epithelial differentiation and proliferative potential. The applied efficacy was examined by implanting them into excisional wounds on both back and paws of hind legs in mice. After 3 weeks, BM-MSC-engineered skin (EGF loaded) treated wounds exhibited accelerated healing with increased re-epithelialization rates and less skin contraction. Furthermore, histological and immunofluorescence staining analysis revealed sweat glands-like structures became more apparent in BM-MSC-engineered skin (EGF loaded) treated wounds but the number of implanted BM-MSCs were decreased gradually in later phases of healing progression. Our study suggests that BM-MSCs delivered by this EGF microspheres-based engineered skin model may be a promising strategy to repair sweat glands and improve cutaneous wound healing after injury and success in this study might provide a potential benefit for BM-MSCs administration clinically. Copyright © 2012 Japanese Society for Investigative Dermatology. Published by Elsevier Ireland Ltd. All rights reserved.

  20. 汽车发动机的维修与保养分析%Repair and maintenance of automobile engine

    Institute of Scientific and Technical Information of China (English)

    陈航

    2013-01-01

    With the continued growth of the national economy, people's living standards improve, the automotive in-dustry significantly increased the pace of development. Car engine is a core part of automotive parts, but also to start the car the only member which is not only to ensure quality performance guarantee safe driving cars, but also extend vehicle life. Therefore, to do routine maintenance and repair car engine work is very important. Articles will be corporate engine repair and maintenance work to discuss, to understand the basic principles of automotive engine, and its routine mainte-nance and repair to propose effective countermeasures.%随着国民经济持续增长,人们生活水平不断提高,汽车工业的发展速度显著提高。汽车发动机是汽车零部件的核心部分,也是启动汽车的唯一部件,其质量性能保障不仅保证汽车安全驾驶,还延长汽车使用寿命。因此,做好汽车发动机日常维修与保养工作十分重要。文章将对企业发动机的维修与保养工作展开讨论,了解汽车发动机的基本原理,并对其日常保养与维修提出有效的对策。

  1. The mechanism of nucleotide excision repair-mediated UV-induced mutagenesis in nonproliferating cells.

    Science.gov (United States)

    Kozmin, Stanislav G; Jinks-Robertson, Sue

    2013-03-01

    Following the irradiation of nondividing yeast cells with ultraviolet (UV) light, most induced mutations are inherited by both daughter cells, indicating that complementary changes are introduced into both strands of duplex DNA prior to replication. Early analyses demonstrated that such two-strand mutations depend on functional nucleotide excision repair (NER), but the molecular mechanism of this unique type of mutagenesis has not been further explored. In the experiments reported here, an ade2 adeX colony-color system was used to examine the genetic control of UV-induced mutagenesis in nondividing cultures of Saccharomyces cerevisiae. We confirmed a strong suppression of two-strand mutagenesis in NER-deficient backgrounds and demonstrated that neither mismatch repair nor interstrand crosslink repair affects the production of these mutations. By contrast, proteins involved in the error-prone bypass of DNA damage (Rev3, Rev1, PCNA, Rad18, Pol32, and Rad5) and in the early steps of the DNA-damage checkpoint response (Rad17, Mec3, Ddc1, Mec1, and Rad9) were required for the production of two-strand mutations. There was no involvement, however, for the Pol η translesion synthesis DNA polymerase, the Mms2-Ubc13 postreplication repair complex, downstream DNA-damage checkpoint factors (Rad53, Chk1, and Dun1), or the Exo1 exonuclease. Our data support models in which UV-induced mutagenesis in nondividing cells occurs during the Pol ζ-dependent filling of lesion-containing, NER-generated gaps. The requirement for specific DNA-damage checkpoint proteins suggests roles in recruiting and/or activating factors required to fill such gaps.

  2. Proper body mechanics from an engineering perspective.

    Science.gov (United States)

    Mohr, Edward G

    2010-04-01

    The economic viability of the manual therapy practitioner depends on the number of massages/treatments that can be given in a day or week. Fatigue or injuries can have a major impact on the income potential and could ultimately reach the point which causes the practitioner to quit the profession, and seek other, less physically demanding, employment. Manual therapy practitioners in general, and massage therapists in particular, can utilize a large variety of body postures while giving treatment to a client. The hypothesis of this paper is that there is an optimal method for applying force to the client, which maximizes the benefit to the client, and at the same time minimizes the strain and effort required by the practitioner. Two methods were used to quantifiably determine the effect of using "poor" body mechanics (Improper method) and "best" body mechanics (Proper/correct method). The first approach uses computer modeling to compare the two methods. Both postures were modeled, such that the biomechanical effects on the practitioner's elbow, shoulder, hip, knee and ankle joints could be calculated. The force applied to the client, along with the height and angle of application of the force, was held constant for the comparison. The second approach was a field study of massage practitioners (n=18) to determine their maximal force capability, again comparing methods using "Improper and Proper body mechanics". Five application methods were tested at three different application heights, using a digital palm force gauge. Results showed that there was a definite difference between the two methods, and that the use of correct body mechanics can have a large impact on the health and well being of the massage practitioner over both the short and long term.

  3. Cell Patterning for Liver Tissue Engineering via Dielectrophoretic Mechanisms

    Directory of Open Access Journals (Sweden)

    Wan Nurlina Wan Yahya

    2014-07-01

    Full Text Available Liver transplantation is the most common treatment for patients with end-stage liver failure. However, liver transplantation is greatly limited by a shortage of donors. Liver tissue engineering may offer an alternative by providing an implantable engineered liver. Currently, diverse types of engineering approaches for in vitro liver cell culture are available, including scaffold-based methods, microfluidic platforms, and micropatterning techniques. Active cell patterning via dielectrophoretic (DEP force showed some advantages over other methods, including high speed, ease of handling, high precision and being label-free. This article summarizes liver function and regenerative mechanisms for better understanding in developing engineered liver. We then review recent advances in liver tissue engineering techniques and focus on DEP-based cell patterning, including microelectrode design and patterning configuration.

  4. Cell Patterning for Liver Tissue Engineering via Dielectrophoretic Mechanisms

    Science.gov (United States)

    Yahya, Wan Nurlina Wan; Kadri, Nahrizul Adib; Ibrahim, Fatimah

    2014-01-01

    Liver transplantation is the most common treatment for patients with end-stage liver failure. However, liver transplantation is greatly limited by a shortage of donors. Liver tissue engineering may offer an alternative by providing an implantable engineered liver. Currently, diverse types of engineering approaches for in vitro liver cell culture are available, including scaffold-based methods, microfluidic platforms, and micropatterning techniques. Active cell patterning via dielectrophoretic (DEP) force showed some advantages over other methods, including high speed, ease of handling, high precision and being label-free. This article summarizes liver function and regenerative mechanisms for better understanding in developing engineered liver. We then review recent advances in liver tissue engineering techniques and focus on DEP-based cell patterning, including microelectrode design and patterning configuration. PMID:24991941

  5. International Joint Conference on Mechanics, Design Engineering & Advanced Manufacturing

    CERN Document Server

    Nigrelli, Vincenzo; Oliveri, Salvatore; Peris-Fajarnes, Guillermo; Rizzuti, Sergio

    2017-01-01

    This book gathers papers presented at the International Joint Conference on Mechanics, Design Engineering and Advanced Manufacturing (JCM 2016), held on 14-16 September, 2016, in Catania, Italy. It reports on cutting-edge topics in product design and manufacturing, such as industrial methods for integrated product and process design; innovative design; and computer-aided design. Further topics covered include virtual simulation and reverse engineering; additive manufacturing; product manufacturing; engineering methods in medicine and education; representation techniques; and nautical, aeronautics and aerospace design and modeling. The book is divided into eight main sections, reflecting the focus and primary themes of the conference. The contributions presented here will not only provide researchers, engineers and experts in a range of industrial engineering subfields with extensive information to support their daily work; they are also intended to stimulate new research directions, advanced applications of t...

  6. Abnormal Base Excision Repair at Trinucleotide Repeats Associated with Diseases: A Tissue-Selective Mechanism

    Directory of Open Access Journals (Sweden)

    Agathi-Vasiliki Goula

    2013-07-01

    Full Text Available More than fifteen genetic diseases, including Huntington’s disease, myotonic dystrophy 1, fragile X syndrome and Friedreich ataxia, are caused by the aberrant expansion of a trinucleotide repeat. The mutation is unstable and further expands in specific cells or tissues with time, which can accelerate disease progression. DNA damage and base excision repair (BER are involved in repeat instability and might contribute to the tissue selectivity of the process. In this review, we will discuss the mechanisms of trinucleotide repeat instability, focusing more specifically on the role of BER.

  7. [Mechanisms of reparative action of a new repair and protect toothpaste].

    Science.gov (United States)

    Elovikova, T M; Ermishina, E Yu; Mikheikina, N I

    The aim of the study was to assess clinical efficacy of Sensodyne repair and protect toothpaste as well as mechanics of its reparative action. Forty-eight patients (29 females and 19 males) were included in the study. The participants brushed twice daily with Sensodyne toothpaste. In 24 patients in addition to clinical examination fluoride, calcium and pH were measured in oral fluid. The study showed OHIS reduction by 40.24% and eradication of tooth hypersensitivity even after single use of the toothpaste in 90% of patients because of sodium monofluorophosphate action.

  8. Research on the possibility of restoring blades while repairing gas turbine engines parts by selective laser melting

    Science.gov (United States)

    Smelov, V. G.; Sotov, A. V.; Agapovichev, A. V.

    2016-07-01

    We study the possibility of restoring the blades of chromium-nickel materials for the repair of parts of gas turbine engines using selective laser melting technology. The stages of preparation of the items to repair and reconditioning are considered in detail, the algorithm of the recovery process to a 3D machine has been developed. Chemical analysis of the raw material and facing material has been performed. Maps of distribution of chemical elements in the fusion zone of the starting material with the surfacing material have been acquired. In order to study the nature of alloying materials fractographic analysis of the places of fusion was performed. A map of distribution of chemical elements in the fusion zone was obtained.

  9. Mechanical Modelling and Computational Issues in Civil Engineering

    OpenAIRE

    2005-01-01

    In this edited book various novel approaches to problems of modern civil engineering are demonstrated. Experts associated within the Lagrange Laboratory present recent research results in civil engineering dealing both with modelling and computational aspects. Many modern topics are covered, such as monumental dams, soil mechanics and geotechnics, granular media, contact and friction problems, damage and fracture, new structural materials, and vibration damping -presenting the state of the ar...

  10. Economical and Managerial Competencies of Bachelors in Mechanical Engineering

    OpenAIRE

    Lizunkov, Vladislav Gennadyevich; Marchuk, Veronika Ivanovna; Malushko, Elena Yurievna; Maletina, Oksana Andreevna; Zavyalova, Anastasia Vyacheslavovna

    2017-01-01

    The paper deals with problems relating to orientation of the market economy with reference to development of economic and managerial competencies by bachelors after graduating from engineering higher schools to meet employers’ requirements, through implementing the Federal State Education Standards (FSES) of the third generation. The case study: training programs for the bachelor’s degree in Mechanical Engineering at Yurga Institute of Technology (Affiliate) of National Research Tomsk Polytec...

  11. Developing economic and managerial competencies of bachelors in mechanical engineering

    OpenAIRE

    Lizunkov Vladislav G.; Minin Michail G.; Malushko Elena Y.; Medvedev Valentin E.

    2016-01-01

    The paper deals with the development problems of economic and managerial competencies of bachelors after graduating from engineering higher schools to meet employers’ requirements, through implementing the Federal State Education Standards (FSES) of the third generation. The case study is conducted on the basis of training programs for the bachelor’s degree in Mechanical Engineering at Yurga Institute of Technology (Affiliate) of National Research Tomsk Polytechnic University. The list of eco...

  12. Developing economic and managerial competencies of bachelors in mechanical engineering

    OpenAIRE

    Lizunkov Vladislav G.; Minin Michail G.; Malushko Elena Y.; Medvedev Valentin E.

    2016-01-01

    The paper deals with the development problems of economic and managerial competencies of bachelors after graduating from engineering higher schools to meet employers’ requirements, through implementing the Federal State Education Standards (FSES) of the third generation. The case study is conducted on the basis of training programs for the bachelor’s degree in Mechanical Engineering at Yurga Institute of Technology (Affiliate) of National Research Tomsk Polytechnic University. The list of eco...

  13. Economical and Managerial Competencies of Bachelors in Mechanical Engineering

    OpenAIRE

    Lizunkov, Vladislav Gennadyevich; Marchuk, Veronika Ivanovna; Malushko, Elena Yurievna; Maletina, Oksana Andreevna; Zavyalova, Anastasia Vyacheslavovna

    2017-01-01

    The paper deals with problems relating to orientation of the market economy with reference to development of economic and managerial competencies by bachelors after graduating from engineering higher schools to meet employers’ requirements, through implementing the Federal State Education Standards (FSES) of the third generation. The case study: training programs for the bachelor’s degree in Mechanical Engineering at Yurga Institute of Technology (Affiliate) of National Research Tomsk Polytec...

  14. Interactive Approach on Experiments in Mechanical Engineering : Vibration

    Science.gov (United States)

    Kumon, Makoto; Torigoe, Ippei; Mizumoto, Ikuro; Yamaguchi, Teruo; Kohzawa, Ryuichi; Ohshima, Yasutaka

    Experiments in the engineering education play important roles in motivating students to study voluntarily. A trial aiming to enhance this effect in the experiment of vibration at Mechanical System Engineering, Kumamoto University is introduced. The trial consists of 1) oral presentation by students, 2) web-based learning system and 3) feedback through reports. An evaluation by questionnaire was conducted to show the validity of this trial. This result revealed that the trial succeeded to encourage students.

  15. 组织工程修复肩袖损伤促进腱骨愈合的研究进展%Progress in tissue-engineering for tendon-to-bone healing after rotator cuff repair

    Institute of Scientific and Technical Information of China (English)

    赵晨; 王蕾

    2015-01-01

    Rotator cuff injury, considered as a resource of pain, disability and dyssomnia to serious decline in the quality of life, is a common disorder of the shoulder joint. Basic principles of rotator cuff repair aim at achieving high initial ifxation strength, maintaining mechanical stability and restoring the anatomic healing of the cuff tendon. After the routine surgical procedure for rotator cuff repair, the biology and histology of the normal enthesis are not restored. Tendon-to-bone healing occurs with a ifbrovascular scar tissue interface that is mechanically inferior to the native insertion site, which may lead to high re-rupture rate. For these reasons, new approaches are required to improve structural healing. Tissue engineering strategies have been suggested to improve the biological environment around the bone-tendon interface and to promote regeneration of the native insertion site. Although experimental applications of growth factors and scaffolds on animal models demonstrate promising results, techniques which can be used in human rotator cuff repair are still very limited. Tissue engineering to improve tendon-to-bone healing has bright future and requires more research before its clinical applications. This review will outline therapies of growth factors, scaffolds and stem cells in tendon healing and rotator cuff repair.

  16. Enhanced mechanical properties of thermosensitive chitosan hydrogel by silk fibers for cartilage tissue engineering.

    Science.gov (United States)

    Mirahmadi, Fereshteh; Tafazzoli-Shadpour, Mohammad; Shokrgozar, Mohammad Ali; Bonakdar, Shahin

    2013-12-01

    Articular cartilage has limited repair capability following traumatic injuries and current methods of treatment remain inefficient. Reconstructing cartilage provides a new way for cartilage repair and natural polymers are often used as scaffold because of their biocompatibility and biofunctionality. In this study, we added degummed chopped silk fibers and electrospun silk fibers to the thermosensitive chitosan/glycerophosphate hydrogels to reinforce two hydrogel constructs which were used as scaffold for hyaline cartilage regeneration. The gelation temperature and gelation time of hydrogel were analyzed by the rheometer and vial tilting method. Mechanical characterization was measured by uniaxial compression, indentation and dynamic mechanical analysis assay. Chondrocytes were then harvested from the knee joint of the New Zealand white rabbits and cultured in constructs. The cell proliferation, viability, production of glycosaminoglycans and collagen type II were assessed. The results showed that mechanical properties of the hydrogel were significantly enhanced when a hybrid with two layers of electrospun silk fibers was made. The results of GAG and collagen type II in cell-seeded scaffolds indicate support of the chondrogenic phenotype for chondrocytes with a significant increase in degummed silk fiber-hydrogel composite for GAG content and in two-layer electrospun fiber-hydrogel composite for Col II. It was concluded that these two modified scaffolds could be employed for cartilage tissue engineering.

  17. MECHANICAL DESIGN CRITERIA FOR INTERVERTEBRAL DISC TISSUE ENGINEERING

    Science.gov (United States)

    Nerurkar, Nandan L.; Elliott, Dawn M.; Mauck, Robert L.

    2009-01-01

    Due to the inability of current clinical practices to restore function to degenerated intervertebral discs, the arena of disc tissue engineering has received substantial attention in recent years. Despite tremendous growth and progress in this field, translation to clinical implementation has been hindered by a lack of well-defined functional benchmarks. Because successful replacement of the disc is contingent upon replication of some or all of its complex mechanical behaviour, it is critically important that disc mechanics be well characterized in order to establish discrete functional goals for tissue engineering. In this review, the key functional signatures of the intervertebral disc are discussed and used to propose a series of native tissue benchmarks to guide the development of engineered replacement tissues. These benchmarks include measures of mechanical function under tensile, compressive and shear deformations for the disc and its substructures. In some cases, important functional measures are identified that have yet to be measured in the native tissue. Ultimately, native tissue benchmark values are compared to measurements that have been made on engineered disc tissues, identifying measures where functional equivalence was achieved, and others where there remain opportunities for advancement. Several excellent reviews exist regarding disc composition and structure, as well as recent tissue engineering strategies; therefore this review will remain focused on the functional aspects of disc tissue engineering. PMID:20080239

  18. 46 CFR 113.35-15 - Mechanical engine order telegraph systems; application.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Mechanical engine order telegraph systems; application...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-15 Mechanical engine order telegraph systems; application. If a mechanical engine order...

  19. Introduction to Analytical Methods for Internal Combustion Engine Cam Mechanisms

    CERN Document Server

    Williams, J J

    2013-01-01

    Modern design methods of Automotive Cam Design require the computation of a range of parameters. This book provides a logical sequence of steps for the derivation of the relevant equations from first principles, for the more widely used cam mechanisms. Although originally derived for use in high performance engines, this work is equally applicable to the design of mass produced automotive and other internal combustion engines.   Introduction to Analytical Methods for Internal Combustion Engine Cam Mechanisms provides the equations necessary for the design of cam lift curves with an associated smooth acceleration curve. The equations are derived for the kinematics and kinetics of all the mechanisms considered, together with those for cam curvature and oil entrainment velocity. This permits the cam shape, all loads, and contact stresses to be evaluated, and the relevant tribology to be assessed. The effects of asymmetry on the manufacture of cams for finger follower and offset translating curved followers is ...

  20. A Concise Introduction to Mechanics of Rigid Bodies Multidisciplinary Engineering

    CERN Document Server

    Huang, L

    2012-01-01

    A Concise Introduction to Mechanics of Rigid Bodies: Multidisciplinary Engineering presents concise, key concepts of kinematics and dynamics of rigid bodies. This compact volume bridges the steep gap between  introductory texts on engineering mechanics, which focus on one and two dimensional motions of particles and rigid bodies, and advanced texts on multi-body dynamics in high dimension spaces  found in multidisciplinary areas like mechatronics, robotics and biomechanics. In the book, rigid body motions in the spaces with different dimensions are described in addition to studies in a uniform framework supported by vector and matrix operations. Rigorous mathematic tools and explanations are provided to clarify the most complex concepts. This book also: Provides practical examples from different engineering areas, offering a link between theoretical fundamentals and everyday applications Offers simplified mathematical equations to clearly present essential theories in robotics and mechanics Presents statics...

  1. AN OVERVIEW OF THE SNS ACCELERATOR MECHANICAL ENGINEERING.

    Energy Technology Data Exchange (ETDEWEB)

    HSEUH, H.; LUDWIG, H.; MAHLER, G.; PAI, C.; PEARSON, C.; RANK, J.; TUOZZOLO, J.; WEI, J.

    2006-06-23

    The Spallation Neutron Source (SNS*) is an accelerator-based neutron source currently nearing completion at Oak Ridge National Laboratory. When completed in 2006, the SNS will provide a 1 GeV, 1.44 MW proton beam to a liquid mercury target for neutron production. SNS is a collaborative effort between six U.S. Department of Energy national laboratories and offered a unique opportunity for the mechanical engineers to work with their peers from across the country. This paper presents an overview of the overall success of the collaboration concentrating on the accelerator ring mechanical engineering along with some discussion regarding the relative merits of such a collaborative approach. Also presented are a status of the mechanical engineering installation and a review of the associated installation costs.

  2. Sputtering. [as deposition technique in mechanical engineering

    Science.gov (United States)

    Spalvins, T.

    1976-01-01

    This paper primarily reviews the potential of using the sputtering process as a deposition technique; however, the manufacturing and sputter etching aspects are also discussed. Since sputtering is not regulated by classical thermodynamics, new multicomponent materials can be developed in any possible chemical composition. The basic mechanism for dc and rf sputtering is described. Sputter-deposition is described in terms of the unique advantageous features it offers such as versatility, momentum transfer, stoichiometry, sputter-etching, target geometry (coating complex surfaces), precise controls, flexibility, ecology, and sputtering rates. Sputtered film characteristics, such as strong adherence and coherence and film morphology, are briefly evaluated in terms of varying the sputtering parameters. Also described are some of the specific industrial areas which are turning to sputter-deposition techniques.

  3. Sputtering. [as deposition technique in mechanical engineering

    Science.gov (United States)

    Spalvins, T.

    1976-01-01

    This paper primarily reviews the potential of using the sputtering process as a deposition technique; however, the manufacturing and sputter etching aspects are also discussed. Since sputtering is not regulated by classical thermodynamics, new multicomponent materials can be developed in any possible chemical composition. The basic mechanism for dc and rf sputtering is described. Sputter-deposition is described in terms of the unique advantageous features it offers such as versatility, momentum transfer, stoichiometry, sputter-etching, target geometry (coating complex surfaces), precise controls, flexibility, ecology, and sputtering rates. Sputtered film characteristics, such as strong adherence and coherence and film morphology, are briefly evaluated in terms of varying the sputtering parameters. Also described are some of the specific industrial areas which are turning to sputter-deposition techniques.

  4. Developing economic and managerial competencies of bachelors in mechanical engineering

    Directory of Open Access Journals (Sweden)

    Lizunkov Vladislav G.

    2016-01-01

    Full Text Available The paper deals with the development problems of economic and managerial competencies of bachelors after graduating from engineering higher schools to meet employers’ requirements, through implementing the Federal State Education Standards (FSES of the third generation. The case study is conducted on the basis of training programs for the bachelor’s degree in Mechanical Engineering at Yurga Institute of Technology (Affiliate of National Research Tomsk Polytechnic University. The list of economic and managerial competencies for bachelors in mechanical engineering is specified according to the third generation FSES, enlarged with new competences based on surveys and analyses after questioning employers. The criteria and indicators are described to identify maturity levels in terms of economic and managerial competencies for bachelors. A structural and functional model for training mechanical engineering bachelors has been tested in the implementation of the bachelor’s degree courses in "Mechanical engineering" at Yurga Institute of Technology (Affiliate of National Research Tomsk Polytechnic University, in the period from 2011 to 2015.

  5. Effect of repetitive loading on the mechanical properties of synthetic hernia repair materials.

    Science.gov (United States)

    Eliason, Braden J; Frisella, Margaret M; Matthews, Brent D; Deeken, Corey R

    2011-09-01

    Hernia repair materials undergo repeated loading while in the body, and the impact on mechanical properties is unknown. It was hypothesized that exposure to repetitive loading would lead to decreased tensile strength and increased strain, and that these differences would become more pronounced with greater loading and unloading sequences. Polypropylene, expanded polytetrafluoroethylene, composite barrier, and partially absorbable meshes were evaluated. Twenty specimens (7.5 × 7.5 cm) were prepared from each material. Five specimens were subjected to ball burst testing to determine baseline biomechanical properties. Cycles of 10, 100, and 1,000 loading sequences were also performed (n = 5 each). BardMesh (CR Bard/Davol), Dualmesh (WL Gore), and Prolene (Ethicon) exhibited significantly reduced tensile strength; BardMesh, Proceed (Ethicon), Prolene, ProLite (Atrium Medical), ProLite Ultra (Atrium Medical), and Ultrapro (Ethicon) exhibited significantly increased strain after exposure to 1,000 cycles compared with their baseline properties. BardMesh and Prolene demonstrated both reduced tensile strength and increased strain values after 1,000 cycles, suggesting that repetitive loading has the greatest effects on these materials. In addition, BardMesh and Prolene exhibited progressively worsening effects as the number of cycles was increased. Deterioration of the tensile strength of the mesh or an increase in the ability of the mesh material to stretch (ie, increased strain values) could potentially lead to hernia recurrence or a poor functional result. However, the results of this study should not be interpreted to mean that hernia repair materials will fail in the body after only 10, 100, or 1,000 cycles. The conditions used in this study were more extreme than most physiologic scenarios and were intended as a pilot investigation into how the mechanical properties of hernia repair materials are affected by in vitro cyclic testing. Copyright © 2011 American College

  6. Engineering three-dimensional cell mechanical microenvironment with hydrogels.

    Science.gov (United States)

    Huang, Guoyou; Wang, Lin; Wang, Shuqi; Han, Yulong; Wu, Jinhui; Zhang, Qiancheng; Xu, Feng; Lu, Tian Jian

    2012-12-01

    Cell mechanical microenvironment (CMM) significantly affects cell behaviors such as spreading, migration, proliferation and differentiation. However, most studies on cell response to mechanical stimulation are based on two-dimensional (2D) planar substrates, which cannot mimic native three-dimensional (3D) CMM. Accumulating evidence has shown that there is a significant difference in cell behavior in 2D and 3D microenvironments. Among the materials used for engineering 3D CMM, hydrogels have gained increasing attention due to their tunable properties (e.g. chemical and mechanical properties). In this paper, we provide an overview of recent advances in engineering hydrogel-based 3D CMM. Effects of mechanical cues (e.g. hydrogel stiffness and externally induced stress/strain in hydrogels) on cell behaviors are described. A variety of approaches to load mechanical stimuli in 3D hydrogel-based constructs are also discussed.

  7. Control Engineering as a Part of Undergraduate Curriculum for Mechanical Engineering in India

    Directory of Open Access Journals (Sweden)

    Akhtar Shagil

    2016-09-01

    Full Text Available In this present study we have traced the genesis of control engineering in the scope of mechanical engineering and then some analysis on its recent developments, their increasing need and how this particular subject has evolved machines functioning nowadays specifically its standard of education in India. We have probed this field right from its starting. We have examined how it is required as a proper course for mechanical engineering students and in which order the evolution in this field is expanding and, at the same time, its level of education in India and where we are in confronting the business need in terms of quality and quantity of students. The point is that it holds significance in near future. Over the years control engineering has been expanding its perimeter in various branches such mechanics, electronics, instrumentation, electrics, chemistry, aeronautics, mechatronics, etc. As a result, numerous interactive feedback structure from the output and the ability to alter the input accordingly have given the world a new era of equipment commonly termed as “smart devices” which have changed the lifestyle of common people. Furthermore, its various applications in different industry have also favored its development. So, some views from the industry prospective have been included to find out about the skills that are required for aspiring and practicing control engineers having mechanical engineering background.

  8. Mechanical Architecture and Engineering of PAZ Instrument

    Science.gov (United States)

    Bautista Juzgado, Victor

    2012-07-01

    PAZ is a highly flexible X-Band Synthetic Aperture Radar satellite devoted to global Earth Observation. It fulfills the strategic needs of the Spanish Government within the National Earth Observation Program. This satellite will be capable of providing high quality SAR images up to very high resolution (e.g. meter and sub- meter). Its flexibility lies on the various instrument modes (Stripmap, ScanSAR, Sporlight...) with a wide number of configurations, both in left and right-looking scanning. The S/C will cover the Earth with a mean revisit time of 1 day taking around 200000 images per day over an area above 300000km2. In the frame of this program, EADS CASA Espacio (ECE) stands as satellite prime contractor as well as responsible for the design and development of the SAR instrument, also called Front End. This paper describes the mechanical architecture, driving requirements, analyses, tests and main challenges found during the Front End development at ECE from the structural point of view.

  9. Multi-scale mechanical response of freeze-dried collagen scaffolds for tissue engineering applications.

    Science.gov (United States)

    Offeddu, Giovanni S; Ashworth, Jennifer C; Cameron, Ruth E; Oyen, Michelle L

    2015-02-01

    Tissue engineering has grown in the past two decades as a promising solution to unresolved clinical problems such as osteoarthritis. The mechanical response of tissue engineering scaffolds is one of the factors determining their use in applications such as cartilage and bone repair. The relationship between the structural and intrinsic mechanical properties of the scaffolds was the object of this study, with the ultimate aim of understanding the stiffness of the substrate that adhered cells experience, and its link to the bulk mechanical properties. Freeze-dried type I collagen porous scaffolds made with varying slurry concentrations and pore sizes were tested in a viscoelastic framework by macroindentation. Membranes made up of stacks of pore walls were indented using colloidal probe atomic force microscopy. It was found that the bulk scaffold mechanical response varied with collagen concentration in the slurry consistent with previous studies on these materials. Hydration of the scaffolds resulted in a more compliant response, yet lesser viscoelastic relaxation. Indentation of the membranes suggested that the material making up the pore walls remains unchanged between conditions, so that the stiffness of the scaffolds at the scale of seeded cells is unchanged; rather, it is suggested that thicker pore walls or more of these result in the increased moduli for the greater slurry concentration conditions.

  10. Thermodynamic and Mechanical Analysis of a Thermomagnetic Rotary Engine

    Science.gov (United States)

    Fajar, D. M.; Khotimah, S. N.; Khairurrijal

    2016-08-01

    A heat engine in magnetic system had three thermodynamic coordinates: magnetic intensity ℋ, total magnetization ℳ, and temperature T, where the first two of them are respectively analogous to that of gaseous system: pressure P and volume V. Consequently, Carnot cycle that constitutes the principle of a heat engine in gaseous system is also valid on that in magnetic system. A thermomagnetic rotary engine is one model of it that was designed in the form of a ferromagnetic wheel that can rotates because of magnetization change at Curie temperature. The study is aimed to describe the thermodynamic and mechanical analysis of a thermomagnetic rotary engine and calculate the efficiencies. In thermodynamic view, the ideal processes are isothermal demagnetization, adiabatic demagnetization, isothermal magnetization, and adiabatic magnetization. The values of thermodynamic efficiency depend on temperature difference between hot and cold reservoir. In mechanical view, a rotational work is determined through calculation of moment of inertia and average angular speed. The value of mechanical efficiency is calculated from ratio between rotational work and heat received by system. The study also obtains exergetic efficiency that states the performance quality of the engine.

  11. Mechanical engineering utilizing advanced engineering tools for the CANDU 9 project

    Energy Technology Data Exchange (ETDEWEB)

    Nuzzo, F.; Yu, S.K.W.; Hedges, K.R. [Atomic Energy of Canada Limited (AECL), Ontario (Canada)

    1998-05-01

    To meet the increasing challenging project requirements such as cost and schedule reduction, AECL has incorporated a comprehensive suite of integrated, advanced engineering tools for CANDU project engineering and delivery. This paper provides a description of the advanced engineering tools developed and used by AECL in the pre-project engineering of the CANDU 9 product and the construction projects such as the construction of two CANDU 6 units in Qinshan, China. The advanced mechanical engineering tools described include: the Process and Instrument Diagram ; the mechanical/piping 3D models; the CADDS/piping analysis interface (PAI) tool; the pipe support design system (SDS) tool; and the powerful equipment database tool - TeddyBase. A description of the enhanced work process will also be provided. The work process improvement is a direct result of the implementation of advanced information technology and the integration of AECL tools with commercial engineering and project tools available in the market. The use of these advanced tools results in better design quality; enhanced presentation of the engineering deliverables to construction and commissioning staff; and potential support to future plant operations (Ref.1). (author). 2 refs., 3 figs.

  12. Survival and SOS response induction in ultraviolet B irradiated Escherichia coli cells with defective repair mechanisms.

    Science.gov (United States)

    Prada Medina, Cesar Augusto; Aristizabal Tessmer, Elke Tatjana; Quintero Ruiz, Nathalia; Serment-Guerrero, Jorge; Fuentes, Jorge Luis

    2016-06-01

    Purpose In this paper, the contribution of different genes involved in DNA repair for both survival and SOS induction in Escherichia coli mutants exposed to ultraviolet B radiation (UVB, [wavelength range 280-315 nm]) was evaluated. Materials and methods E. coli strains defective in uvrA, oxyR, recO, recN, recJ, exoX, recB, recD or xonA genes were used to determine cell survival. All strains also had the genetic sulA::lacZ fusion, which allowed for the quantification of SOS induction through the SOS Chromotest. Results Five gene products were particularly important for survival, as follows: UvrA > RecB > RecO > RecJ > XonA. Strains defective in uvrA and recJ genes showed elevated SOS induction compared with the wild type, which remained stable for up to 240 min after UVB-irradiation. In addition, E. coli strains carrying the recO or recN mutation showed no SOS induction. Conclusions The nucleotide excision and DNA recombination pathways were equally used to repair UVB-induced DNA damage in E. coli cells. The sulA gene was not turned off in strains defective in UvrA and RecJ. RecO protein was essential for processing DNA damage prior to SOS induction. In this study, the roles of DNA repair proteins and their contributions to the mechanisms that induce SOS genes in E. coli are proposed.

  13. Project-Based Laboratory Experiences in Mechanical Engineering

    Directory of Open Access Journals (Sweden)

    Narendra Sharma

    2011-12-01

    Full Text Available In this paper we describe project-based laboratories in Mechanical Engineering designed to provide semester-long team experiences which mimic the real life industrial processes of design, development, testing and optimization. The labs are focused on courses at the sophomore level and thus require special attention to constraints of student backgrounds and experience. This paper describes laboratory projects in Dynamics and Fluid Mechanics.

  14. Tissue engineering repair for femoral head necrosis%股骨头坏死的组织工程修复

    Institute of Scientific and Technical Information of China (English)

    龙腾河; 崔惠勤; 李涛

    2012-01-01

    BACKGROUND: The development of tissue engineering technique changed the manner for treating bone defect. Because bone tissues are reproducible, more and more medical investigators paid a great attention on application of tissue engineering in treatment of femoral head necrosis.OBJECTIVE: To summarize the tissue engineering repair manner of femoral head necrosis, and to explore the perspective of regenerative medicine in bone tissue engineering.METHODS: We retrieved articles regarding tissue engineering techniques in repair of femoral head necrosis from aspects of frontier fields of tissue engineering, including stem cells, tissue construction and biomechanics, orthopedics biomaterial, artificial prosthetic replacement, bone graft transplantation published from January 2000 to December 2011. Repetitive or Meta analysis articles were excluded. A total of 30 representative articles were analyzed.RESULTS AND CONCLUSION: With the progression of regenerative medicine, tissue engineering technique had been widely used in repair of femoral head necrosis, containing stem cells from different sources transplantation for treating femoral head necrosis, inflammatory factor and femora head necrosis, construction and biomechanical analysis of finite element model of femoral head necrosis, varied giant molecular organism bone scaffold in repair of femoral head necrosis, artificial bone implantation and artificial hip joint replacement. However, present tissue engineering in treatment of femoral head necrosis is still in animal experiment and empirical treatment levels.%背景 随着组织工程学技术的发展,改变了治疗骨缺损的传统治疗模式.由于骨组织是可再生组织,医学研究者们越来越重视组织工程在股骨头坏死治疗中的应用.目的 总结股骨头坏死的组织工程修复手段,探索再生医学在骨组织工程领域的医用前景.方法 从组织工程医学关注的几个前沿领域,包括 "干细胞、组织构建与生物

  15. Basic Gasoline Engine Mechanics. Florida Vocational Program Guide.

    Science.gov (United States)

    University of South Florida, Tampa. Dept. of Adult and Vocational Education.

    This packet contains a program guide and Career Merit Achievement Plan (Career MAP) for the implementation of a basic gasoline engine mechanics program in Florida secondary and postsecondary schools. The program guide describes the program content and structure, provides a program description, lists job titles under the program, and includes a…

  16. Evaluating Risk Awareness in Undergraduate Students Studying Mechanical Engineering

    Science.gov (United States)

    Langdon, G. S.; Balchin, K.; Mufamadi, P.

    2010-01-01

    This paper examines the development of risk awareness among undergraduate students studying mechanical engineering at a South African university. A questionnaire developed at the University of Liverpool was modified and used on students from the first, second and third year cohorts to assess their awareness in the areas of professional…

  17. Evaluating Risk Awareness in Undergraduate Students Studying Mechanical Engineering

    Science.gov (United States)

    Langdon, G. S.; Balchin, K.; Mufamadi, P.

    2010-01-01

    This paper examines the development of risk awareness among undergraduate students studying mechanical engineering at a South African university. A questionnaire developed at the University of Liverpool was modified and used on students from the first, second and third year cohorts to assess their awareness in the areas of professional…

  18. A Plastic Damage Mechanics Model for Engineered Cementitious Composites

    DEFF Research Database (Denmark)

    Dick-Nielsen, Lars; Stang, Henrik; Poulsen, Peter Noe

    2007-01-01

    This paper discusses the establishment of a plasticity-based damage mechanics model for Engineered Cementitious Composites (ECC). The present model differs from existing models by combining a matrix and fiber description in order to describe the behavior of the ECC material. The model provides in...

  19. Skeletal myoblasts for heart regeneration and repair: state of the art and perspectives on the mechanisms for functional cardiac benefits.

    Science.gov (United States)

    Formigli, L; Zecchi-Orlandini, S; Meacci, E; Bani, D

    2010-01-01

    Until recently, skeletal myoblasts (SkMBs) have been the most widely used cells in basic research and clinical trials of cell based therapy for cardiac repair and regeneration. Although SkMB engraftment into the post-infarcted heart has been consistently found to improve cardiac contractile function, the underlying therapeutic mechanisms remain still a matter of controversy and debate. This is basically because SkMBs do not attain a cardiac-like phenotype once homed into the diseased heart nor they form a contractile tissue functionally coupled with the surrounding viable myocardium. This issue of concern has generated the idea that the cardiotropic action of SkMBs may depend on the release of paracrine factors. However, the paracrine hypothesis still remains ill-defined, particularly concerning the identification of the whole spectrum of cell-derived soluble factors and details on their cardiac effects. In this context, the possibility to genetically engineering SkMBs to potentate their paracrine attitudes appears particularly attractive and is actually raising great expectation. Aim of the present review is not to cover all the aspects of cell-based therapy with SkMBs, as this has been the object of previous exhaustive reviews in this field. Rather, we focused on novel aspects underlying the interactions between SkMBs and the host cardiac tissues which may be relevant for directing the future basic and applied research on SkMB transplantation for post ischemic cardiac dysfunction.

  20. [Metallothionein-I/II in brain injury repair mechanism and its application in forensic medicine].

    Science.gov (United States)

    Li, Dong; Li, Ru-bo; Lin, Ju-li

    2013-10-01

    Metallothionein (MT) is a kind of metal binding protein. As an important member in metallothionein family, MT-I/II regulates metabolism and detoxication of brain metal ion and scavenges free radicals. It is capable of anti-inflammatory response and anti-oxidative stress so as to protect the brain tissue. During the repair process of brain injury, the latest study showed that MT-I/II could stimulate brain anti-inflammatory factors, growth factors, neurotrophic factors and the expression of the receptor, and promote the extension of axon of neuron, which makes contribution to the regeneration of neuron and has important effect on the recovery of brain injury. Based on the findings, this article reviews the structure, expression, distribution, adjustion, function, mechanism in the repair of brain injury of MT-I/II and its application prospect in forensic medicine. It could provide a new approach for the design and manufacture of brain injury drugs as well as for age estimation of the brain injury.

  1. Understanding the molecular mechanism of formaldehyde-induced DNA-protein crosslink repair

    Science.gov (United States)

    Formaldehyde induces DNA-protein crosslinks (DPCs) in several experimental in vitro and in vivo test systems, as well as in exposed human workers. DPCs are repaired by several DNA repair pathways in different species, but the molecular understanding of DPC repair in human tissues...

  2. Mechanical stimulation in the engineering of heart muscle.

    Science.gov (United States)

    Liaw, Norman Yu; Zimmermann, Wolfram-Hubertus

    2016-01-15

    Recreating the beating heart in the laboratory continues to be a formidable bioengineering challenge. The fundamental feature of the heart is its pumping action, requiring considerable mechanical forces to compress a blood filled chamber with a defined in- and outlet. Ventricular output crucially depends on venous loading of the ventricles (preload) and on the force generated by the preloaded ventricles to overcome arterial blood pressure (afterload). The rate of contraction is controlled by the spontaneously active sinus node and transmission of its electrical impulses into the ventricles. The underlying principles for these physiological processes are described by the Frank-Starling mechanism and Bowditch phenomenon. It is essential to consider these principles in the design and evaluation of tissue engineered myocardium. This review focuses on current strategies to evoke mechanical loading in hydrogel-based heart muscle engineering.

  3. Study of Mechanical Product Rapid Design Based on Knowledge Engineering

    Institute of Scientific and Technical Information of China (English)

    TAI Li-gang; ZHONG Ting-xiu

    2005-01-01

    This paper proposes a mechanical product intelligent rapid design approach based on integrated technologies. Adopting knowledge based engineering to reuse and manage product design knowledge, and combining feature modeling and parametric design based on existing CAD/CAE/CAM system and technology of product family modeling and engineering database, the system establishes a product family knowledge base, which mainly including product family case base and rule base. The system also utilizes WEB technology to let customers to individually customize products remotely through internet. And an applicable example is given in the end.

  4. International Stand of Ukrainian Mechanical Engineering in the European Economy

    Directory of Open Access Journals (Sweden)

    Anastasia A. Goncharova

    2014-03-01

    Full Text Available The article analyses the significant changes in the society that have taken place in Ukraine for the past twenty-five years that considerably influenced the structure and dynamics of mechanical engineering, which, due to objective and subjective reasons, is not ready for large-scale transformational actions. The author has also investigated the dynamics of changes, taking place in the machine-building complex of Ukraine. There have been identified structural changes of the industrial complex that occurred during the crisis and post-crisis period. The article has identified the position of Ukrainian engineering in the European economy.

  5. 2014 Joint Conference on Mechanical Design Engineering and Advanced Manufacturing

    CERN Document Server

    Daidie, Alain; Eynard, Benoit; Paredes, Manuel

    2016-01-01

    Covering key topics in the field such as technological innovation, human-centered sustainable engineering and manufacturing, and manufacture at a global scale in a virtual world, this book addresses both advanced techniques and industrial applications of key research in interactive design and manufacturing. Featuring the full papers presented at the 2014 Joint Conference on Mechanical Design Engineering and Advanced Manufacturing, which took place in June 2014 in Toulouse, France, it presents recent research and industrial success stories related to implementing interactive design and manufacturing solutions.

  6. Contact mechanics of reverse engineered distal humeral hemiarthroplasty implants.

    Science.gov (United States)

    Willing, Ryan; King, Graham J W; Johnson, James A

    2015-11-26

    Erosion of articular cartilage is a concern following distal humeral hemiarthroplasty, because native cartilage surfaces are placed in contact with stiff metallic implant components, which causes decreases in contact area and increases in contact stresses. Recently, reverse engineered implants have been proposed which are intended to promote more natural contact mechanics by reproducing the native bone or cartilage shape. In this study, finite element modeling is used in order to calculate changes in cartilage contact areas and stresses following distal humeral hemiarthroplasty with commercially available and reverse engineered implant designs. At the ulna, decreases in contact area were -34±3% (p=0.002), -27±1% (pengineered and cartilage reverse engineered designs, respectively. Peak contact stresses increased by 461±57% (p=0.008), 387±127% (p=0.229) and 165±16% (p=0.003). At the radius, decreases in contact area were -21±3% (p=0.013), -13±2% (p0.999), 241±32% (p=0.010) and 61±10% (p=0.021). Between the three different implant designs, the cartilage reverse engineered design yielded the largest contact areas and lowest contact stresses, but was still unable to reproduce the contact mechanics of the native joint. These findings align with a growing body of evidence indicating that although reverse engineered hemiarthroplasty implants can provide small improvements in contact mechanics when compared with commercially available designs, further optimization of shape and material properties is required in order reproduce native joint contact mechanics.

  7. A new theoretical formula for fractionated radiotherapy based on a saturable cellular repair mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Reyes, A. (Servicio de Radioterapia, Hospital Clinico y Provincial de Barcelona (Spain)); Farrus, B. (Servicio de Radioterapia, Hospital Clinico y Provincial de Barcelona (Spain)); Biete, A. (Servicio de Radioterapia, Hospital Clinico y Provincial de Barcelona (Spain))

    1993-01-01

    Recently we have published a new model of survival cellular response to radiation based on the existence of a saturable cellular repair mechanism. In the present paper we extend the predictions of this model of calculating the change in total dose necessary to achieve an equal response in a tissue when the dose per fraction in a radiotherapy fractionation schedule is varied. The model provides a new explanation of the difference between late and early radiation reactions. Results obtained from the model for different tissues and standard fractionation schedules are approximately equal to those obtained by the L.Q. (linear-quadratic) model. The model is compatible with in vitro survival curves that are straight at high doses. (orig.).

  8. PGS:Gelatin Nanofibrous Scaffolds with Tunable Mechanical and Structural Properties for Engineering Cardiac Tissues

    Science.gov (United States)

    Kharaziha, Mahshid; Nikkhah, Mehdi; Shin, Su-Ryon; Annabi, Nasim; Masoumi, Nafiseh; Gaharwar, Akhilesh K.; Camci-Unal, Gulden; Khademhosseini, Ali

    2013-01-01

    A significant challenge in cardiac tissue engineering is the development of biomimetic grafts that can potentially promote myocardial repair and regeneration. A number of approaches have used engineered scaffolds to mimic the architecture of the native myocardium tissue and precisely regulate cardiac cell functions. However previous attempts have not been able to simultaneously recapitulate chemical, mechanical, and structural properties of the myocardial extracellular matrix (ECM). In this study, we utilized an electrospinning approach to fabricate elastomeric biodegradable poly(glycerol-sebacate) (PGS):gelatin scaffolds with a wide range of chemical composition, stiffness and anisotropy. Our findings demonstrated that through incorporation of PGS, it is possible to create nanofibrous scaffolds with well-defined anisotropy that mimics the left ventricular myocardium architecture. Furthermore, we studied attachment, proliferation, differentiation and alignment of neonatal rat cardiac fibroblast cells (CFs) as well as protein expression, alignment, and contractile function of cardiomyocyte (CMs) on PGS:gelatin scaffolds with variable amount of PGS. Notably, aligned nanofibrous scaffold, consisting of 33 wt. % PGS, induced optimal synchronous contractions of CMs while significantly enhanced cellular alignment. Overall, our study suggests that the aligned nanofibrous PGS:gelatin scaffold support cardiac cell organization, phenotype and contraction and could potentially be used to develop clinically relevant constructs for cardiac tissue engineering. PMID:23747008

  9. The Prevalence of Musculoskeletal Disorder and the Association with Risk Factors among Auto Repair Mechanics in Klang Valley, Malaysia

    Directory of Open Access Journals (Sweden)

    Ahmad Faisal AHMAD NASARUDDIN

    2015-10-01

    Full Text Available Background: The primary objective of this study was to determine the association between risk factors and the prevalence of musculoskeletal disorder (MSD among auto repair mechanics in Klang Valley, Malaysia.Methods: Overall, 191 mechanics from eight auto repair centers in Klang Valley, Malaysia were stratified sampling as participants of this study. A modified version of the general Standardized Nordic Questionnaire was used for analyses of perceived MSD in nine different parts of the body. Rapid Upper Limb Assessment (RULA, vibration measurement on hand power tool, questionnaire on job content, force exertion was used in this study. Direct logistic regression was performed to assess the impact of risk factors on the MSD prevalence. The probability limits for evaluating statistical significance was P < 0.05.Results: 87.4% of auto repair mechanics suffered from MSD. Logistic regression analysis revealed that factors were associated with symptoms on MSD: RULA (7.933, 95% CI 4.637-13.573 and orceful exertion (3.173, 95% CI 1.194 – 8.432. The magnitude of vibration of power tool exceeds action level 2.5m/s2 with (Mean=3.99+S.E. 0.071 and showed significant association with MSD in this study (P<0.05.Conclusion: Auto repair mechanics at auto repair centers in Klang Valley are likely to be exposed to a variety of ergonomic hazards and risk factors. Therefore, ergonomics awareness between employer and employee with training and information sharing shall be increase to reduce the prevalence of MSDs. Keywords: Musculoskeletal disorder (MSD, Auto repair mechanics, Hand arm vibration

  10. Maximum-power quantum-mechanical Carnot engine.

    Science.gov (United States)

    Abe, Sumiyoshi

    2011-04-01

    In their work [J. Phys. A 33, 4427 (2000)], Bender, Brody, and Meister have shown by employing a two-state model of a particle confined in the one-dimensional infinite potential well that it is possible to construct a quantum-mechanical analog of the Carnot engine through changes of both the width of the well and the quantum state in a specific manner. Here, a discussion is developed about realizing the maximum power of such an engine, where the width of the well moves at low but finite speed. The efficiency of the engine at the maximum power output is found to be universal independently of any of the parameters contained in the model.

  11. Innovative Mechanical Engineering Technologies, Equipment and Materials-2013

    Science.gov (United States)

    Ilnaz Izailovich, Fayrushin; Nail Faikovich, Kashapov; Mahmut Mashutovich, Ganiev

    2014-12-01

    In the period from 25 to 27 September 2013 the city of Kazan hosted the International Scientific Conference "Innovative mechanical engineering technologies, equipment and materials - 2013" (IRTC "IMETEM - 2013"). The conference was held on the grounds of "Kazanskaya Yarmarka" (Kazan). The conference plenary meeting was held with the participation of the Republic of Tatarstan, breakout sessions, forum "Improving the competitiveness and efficiency of engineering enterprises in the WTO" and a number of round tables. Traditionally, the event was followed by the 13th International specialized exhibition "Engineering. Metalworking. Kazan ", in which were presented the development of innovative enterprises in the interests of the Russian Federation of Industry of Republic of Tatarstan, to support the "Foundation for Assistance to Small Innovative Enterprises in Science and Technology" and the 8th specialized exhibition "TechnoWelding". Kashapov Nail, D.Sc., professor (Kazan Federal University)

  12. A real CDIO mechanical engineering project in 4th semester

    DEFF Research Database (Denmark)

    Lauritsen, Aage Birkkjær

    the components as parts of a complex system. The semester project design is developed on basis of these considerations. The semester consists of 4 theory courses in: thermodynamics, control- and simulation of dynamic systems, electronics and hydraulic systems. The project work is performed in groups of 4......In the past 6 years at the mechanical engineering study at the Engineering College of Aarhus we have been practicing project work on 4th Semester in the design of energy technology systems. In my presentation, I will give a description of the project, and the thoughts behind; pedagogic......-didactic as well as technical and professional considerations. The project is presently a permanent part of the 4th semester and counts as one third of the semester. The semester's theme is Energy-and System Design. Content on 4th semester is organized in light of which skills an engineer must possess in the field...

  13. Creating mechanisms of toxic substances emission of combustion engines

    Directory of Open Access Journals (Sweden)

    Jankowski Antoni

    2015-12-01

    Full Text Available The paper analyses the mechanisms of creation of toxic exhaust gases, which mainly derived from inexact fuel metering and improper air-fuel mixture preparation. The paper describes the process of creating toxic components in the exhaust gases of piston engines during engine operation, and impact on the emission of these components determining the composition of the fuel mixture determined equivalence factor Φ. The principal mechanisms of formation of toxic exhaust gases, in particular nitrogen oxides, carbon monoxide and hydrocarbons, and also essential according to create each of toxic exhaust gases are the subject of the paper. Moreover, empirical relationships, by means of which it is possible to determine the time of creation of the individual components of toxic exhaust gases, are presented. For example, one of the mechanisms for prompt formation of nitrogen oxides and hydrocarbons graphic illustration of formation as a function of crank angle is described. At the conclusion, the summary and significance of information on creation mechanisms of toxic components in the exhaust gases of piston engines are presented.

  14. Something Old, Something New: Integrating Engineering Practice into the Teaching of Engineering Mechanics.

    Science.gov (United States)

    Miller, Gregory R.; Cooper, Stephen C.

    1995-01-01

    Presents a multifaceted method for teaching engineering mechanics to satisfy several desiderata. This approach includes design projects, group work, basic competency exams, computational environments for simulating and visualizing phenomena, multimedia instructional tools, hands-on experiences, and student presentations. Describes the materials…

  15. Interactive training model of TRIZ for mechanical engineers in China

    Science.gov (United States)

    Tan, Runhua; Zhang, Huangao

    2014-03-01

    Innovation is a process of taking an original idea and converting it into a business value, in which the engineers face some inventive problems which can be solved hardly by experience. TRIZ, as a new theory for companies in China, provides both conceptual and procedural knowledge for finding and solving inventive problems. Because the government plays a leading role in the diffusion of TRIZ, too many companies from different industries are waiting to be trained, but the quantity of the trainers mastering TRIZ is incompatible with that requirement. In this context, to improve the training effect, an interactive training model of TRIZ for the mechanical engineers in China is developed and the implementation in the form of training classes is carried out. The training process is divided into 6 phases as follows: selecting engineers, training stage-1, finding problems, training stage-2, finding solutions and summing up. The government, TRIZ institutions and companies to join the programs interact during the process. The government initiates and monitors a project in form of a training class of TRIZ and selects companies to join the programs. Each selected companies choose a few engineers to join the class and supervises the training result. The TRIZ institutions design the training courses and carry out training curriculum. With the beginning of the class, an effective communication channel is established by means of interview, discussion face to face, E-mail, QQ and so on. After two years training practices, the results show that innovative abilities of the engineers to join and pass the final examinations increased distinctly, and most of companies joined the training class have taken congnizance of the power of TRIZ for product innovation. This research proposes an interactive training model of TRIZ for mechanical engineers in China to expedite the knowledge diffusion of TRIZ.

  16. Enhanced mechanical properties of thermosensitive chitosan hydrogel by silk fibers for cartilage tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Mirahmadi, Fereshteh [Faculty of Biomedical Engineering, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); National Cell Bank of Iran, Pasteur Institute of Iran, Tehran (Iran, Islamic Republic of); Tafazzoli-Shadpour, Mohammad, E-mail: Tafazoli@aut.ac.ir [Faculty of Biomedical Engineering, Amirkabir University of Technology, Tehran (Iran, Islamic Republic of); Shokrgozar, Mohammad Ali, E-mail: mashokrgozar@pasteur.ac.ir [National Cell Bank of Iran, Pasteur Institute of Iran, Tehran (Iran, Islamic Republic of); Bonakdar, Shahin [National Cell Bank of Iran, Pasteur Institute of Iran, Tehran (Iran, Islamic Republic of)

    2013-12-01

    Articular cartilage has limited repair capability following traumatic injuries and current methods of treatment remain inefficient. Reconstructing cartilage provides a new way for cartilage repair and natural polymers are often used as scaffold because of their biocompatibility and biofunctionality. In this study, we added degummed chopped silk fibers and electrospun silk fibers to the thermosensitive chitosan/glycerophosphate hydrogels to reinforce two hydrogel constructs which were used as scaffold for hyaline cartilage regeneration. The gelation temperature and gelation time of hydrogel were analyzed by the rheometer and vial tilting method. Mechanical characterization was measured by uniaxial compression, indentation and dynamic mechanical analysis assay. Chondrocytes were then harvested from the knee joint of the New Zealand white rabbits and cultured in constructs. The cell proliferation, viability, production of glycosaminoglycans and collagen type II were assessed. The results showed that mechanical properties of the hydrogel were significantly enhanced when a hybrid with two layers of electrospun silk fibers was made. The results of GAG and collagen type II in cell-seeded scaffolds indicate support of the chondrogenic phenotype for chondrocytes with a significant increase in degummed silk fiber–hydrogel composite for GAG content and in two-layer electrospun fiber–hydrogel composite for Col II. It was concluded that these two modified scaffolds could be employed for cartilage tissue engineering. - Highlights: • Chitosan hydrogel composites fabricated by two forms of silk fiber • Silk fibers provide structural support for the hydrogel matrix. • The mechanical properties of hydrogel significantly improved by associating with silk. • Production of GAG and collagen type II was demonstrated within the scaffolds.

  17. Dynamic Route Shortening and Route Repairing Mechanism for Mobile Ad Hoc Networks

    Directory of Open Access Journals (Sweden)

    T. R. Rangaswamy

    2012-01-01

    Full Text Available Problem statement: Ad hoc Networks are wireless networks without any fixed infrastructure. The network topology changes frequently and unpredictably due to the random movement of the nodes. The ad hoc on Demand Distant Vector Routing (AODV protocol works in a dynamic fashion, by establishing a route on demand and continues that route until it breaks. Due to the changing network topology of ad hoc networks, if other routes with less hop count become available, the network topology is not able to adapt until the route break occurs. Hence in the route shortening scheme is some redundant nodes in the active route is replaced with a node that is not on the active route. When there is any link failure between any two nodes, the alternative route with optimum route to be constructed and not sending RRER message to the source node to initiate the route discovery process again. Approach: This study proposes a new routing protocol called, Dynamic Route Shortening and Repairing mechanism (DRSR. The route shortening is incorporated with route repairing mechanism, to improve the performance of the AODV. The route shortening scheme works by replacing some redundant nodes in the active route, with a node that is not on the active route. If there is a link failure between the two nodes, the route repairing mechanism repairs the route, by using the nodes that are close enough to the route to overhear the message. Whenever the links go down, the DRSR replaces the failed links with the optimum route that is adjacent to the main route and not sending and RRER message to the source node to initiate the route discovery process again. The alternative route construction process could be initiated at any time, not just when a route has failed. The dynamically constructed alternative route’s information is passed on to the upstream nodes, which then determine by themselves when to direct their packets to the Normal 0 false false false EN-US X

  18. Formula student as part of a mechanical engineering curriculum

    Science.gov (United States)

    Davies, Huw Charles

    2013-10-01

    Formula Student (FS) is a multi-university student design competition managed by the UK Institution of Mechanical Engineers. Students are required to demonstrate and prove their creativity and engineering skills through the design, manufacture and financing of a small formula style race car. This paper seeks to explore the educational value that derives from the FS activity through a series of semi-structured interviews with key stakeholders. Through the analysis of the interview data, it was found that the FS activity supported development of student skills and competencies in the following areas: use of engineering knowledge to support the application of existing and emerging technology; application of theoretical and practical knowledge to the solution of engineering problems; development of technical and commercial management skills; development of effective interpersonal skills, including communication skills; and demonstration of personal commitment to professional development. In addition, a number of areas for implementing 'good practise' have been identified. The information herein supports educators in their responsibility to help meet the needs of the engineering industry for high quality graduates.

  19. Integration of Social Sciences and Humanities into Mechanical Engineering Curriculum

    Directory of Open Access Journals (Sweden)

    Nikša Dubreta

    2014-04-01

    Full Text Available Article deals with ways in which social sciences and humanities have been integrated from the 1980s to the present day into curriculum of Faculty of Mechanical Engineering and Naval Architecture at University of Zagreb, Croatia. After a brief review and summary of selected research and theoretical contributions to the subject theme, a specific research setting is indicated and contextualized. Elements of socio-historical approach are established primarily through analysis of corresponding documents: curriculums from the 1980s, 1990s and 2000s and from key documents on strategic development of the Faculty. It is stressed that social sciences and humanities topics are continually represented in mechanical engineering study program as legitimate, but separate unit, poorly integrated in the main engineering courses. Together with more or less expressed orientation toward micro-social and micro-economical issues in industry and business, it points to the main features in continuity of establishing the field of social sciences and humanities. Finally, it is shown that chances to widen and enrich aforementioned field are in close relation to the character of engineering and its social contextualization expressed in a key Faculty’s strategic documents.

  20. MULTIDISCIPLINARY PROJECTS FOR SECOND YEAR CHEMICAL AND MECHANICAL ENGINEERING STUDENTS

    Directory of Open Access Journals (Sweden)

    MARWAN M. SHAMEL

    2013-04-01

    Full Text Available In the second semester of the second year of a Mechanical Engineering course, students are supposed to take a Module Outside the Main Discipline (MOMD. This module is chosen to be “Product Design Exercise” a module that is offered to Chemical Engineering students at the same stage. The aim was to expose students from both disciplines to an environment in which they are encouraged to interact with and engage team members with a relatively different background. The students were divided into eight groups all comprised of Chemical and Mechanical Engineering students, and they were offered different open-ended projects that were selected to exploit the knowledge developed by the students thus far and they were slightly skewed towards Chemical Engineering. The students demonstrated a high level of cooperation and motivation throughout the period of the project. Effective communication and closing of knowledge gaps were prevalent. At the end of the project period, students produced a journal paper in lieu of the project report.

  1. Combination of biochemical and mechanical cues for tendon tissue engineering.

    Science.gov (United States)

    Testa, Stefano; Costantini, Marco; Fornetti, Ersilia; Bernardini, Sergio; Trombetta, Marcella; Seliktar, Dror; Cannata, Stefano; Rainer, Alberto; Gargioli, Cesare

    2017-05-04

    Tendinopathies negatively affect the life quality of millions of people in occupational and athletic settings, as well as the general population. Tendon healing is a slow process, often with insufficient results to restore complete endurance and functionality of the tissue. Tissue engineering, using tendon progenitors, artificial matrices and bioreactors for mechanical stimulation, could be an important approach for treating rips, fraying and tissue rupture. In our work, C3H10T1/2 murine fibroblast cell line was exposed to a combination of stimuli: a biochemical stimulus provided by Transforming Growth Factor Beta (TGF-β) and Ascorbic Acid (AA); a three-dimensional environment represented by PEGylated-Fibrinogen (PEG-Fibrinogen) biomimetic matrix; and a mechanical induction exploiting a custom bioreactor applying uniaxial stretching. In vitro analyses by immunofluorescence and mechanical testing revealed that the proposed combined approach favours the organization of a three-dimensional tissue-like structure promoting a remarkable arrangement of the cells and the neo-extracellular matrix, reflecting into enhanced mechanical strength. The proposed method represents a novel approach for tendon tissue engineering, demonstrating how the combined effect of biochemical and mechanical stimuli ameliorates biological and mechanical properties of the artificial tissue compared to those obtained with single inducement. © 2017 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.

  2. Role of tissue engineered tendon in tendon repair%组织工程化肌腱在肌腱修复过程中的作用

    Institute of Scientific and Technical Information of China (English)

    李荣

    2011-01-01

    OBJECTIVE: To review the research progress of tendon tissue engineering in the process of tendon repair.METHODS: A computer-based search of PubMed database and VIP database from January 1993 to October 2009 was performed for articles regarding the tendon tissue engineering, bio-mechanical analysis of tendon scaffolds, biomaterials'application in tendon tissue engineering and tissue engineering technology in the clinical application of tendon defect repair.English key words are "tendon transplantation, tissue engineering, biological material, cell stent", Chinese key words are "tendon transplantation, tissue engineering, biomaterials, cell scaffold". A total of 132 literatures were screened out.RESULTS: At present, the tendon tissue engineering research has achieved remarkable results, but there are still some problems for clinical practice and mass production. Many issues need to be further studied and solved prior to tissue engineering truly becomes a treatment of tendon defect and fu nctional reconstruction, such as the best source of seed cells, the ideal scaffold material, the best culture conditions and detection methods of implantation in vivo.CONCLUSION: Truly realizing the replacement of human tissues and organs with the in vitro prefabricated living implant, still faces many challenges.%目的:综述肌腱组织工程在肌腱修复过程中的应用进展.方法:应用计算机检索1993-01/2009-10 PubMed数据库及维普数据库有关肌腱组织工程研究进展、肌腱支架材料生物力学分析、生物材料在肌腱组织工程中应用及组织工程技术在修复肌腱缺损临床应用方面的相关文献,英文检索词为"tendon transplantation,tissue engineering,biologicalmaterial,cell stent",中文检索词为"肌腱移植,组织工程,生物材料,细胞支架".检索文献量总计132篇. 结果:目前组织工程化肌腱的研究已经取得了显著的成果,但要真正应用于临床,大批量生产,仍存在一些问题.诸

  3. A Bilayer Engineered Skin Substitute for Wound Repair in an Irradiation-Impeded Healing Model on Rat

    OpenAIRE

    2015-01-01

    Objective: An engineered skin substitute is produced to accelerate wound healing by increasing the mechanical strength of the skin wound via high production of collagen bundles. During the remodeling stage of wound healing, collagen deposition is the most important event. The collagen deposition process may be altered by nutritional deficiency, diabetes mellitus, microbial infection, or radiation exposure, leading to impaired healing. This study describes the fabrication of an engineered bila...

  4. Analysis of the Lifecycle of Mechanical Engineering Products

    Science.gov (United States)

    Gubaydulina, R. H.; Gruby, S. V.; Davlatov, G. D.

    2016-08-01

    Principal phases of the lifecycle of mechanical engineering products are analyzed in the paper. The authors have developed methods and procedures to improve designing, manufacturing, operating and recycling of the machine. It has been revealed that economic lifecycle of the product is a base for appropriate organization of mechanical engineering production. This lifecycle is calculated as a minimal sum total of consumer and producer costs. The machine construction and its manufacturing technology are interrelated through a maximal possible company profit. The products are to be recycled by their producer. Recycling should be considered as a feedback phase, necessary to make the whole lifecycle of the product a constantly functioning self-organizing system. The principles, outlined in this paper can be used as fundamentals to develop an automated PLM-system.

  5. Catastrophe theory and its application status in mechanical engineering

    Directory of Open Access Journals (Sweden)

    Jinge LIU

    Full Text Available Catastrophe theory is a kind of mathematical method which aims to apply and interpret the discontinuous phenomenon. Since its emergence, it has been widely used to explain a variety of emergent phenomena in the fields of natural science, social science, management science and some other science and technology fields. Firstly, this paper introduces the theory of catastrophe in several aspects, such as its generation, radical principle, basic characteristics and development. Secondly, it summarizes the main applications of catastrophe theory in the field of mechanical engineering, focusing on the research progress of catastrophe theory in revealing catastrophe of rotor vibration state, analyzing friction and wear failure, predicting metal fracture, and so on. Finally, it advises that later development of catastrophe theory should pay more attention to the combination of itself with other traditional nonlinear theories and methods. This paper provides a beneficial reference to guide the application of catastrophe theory in mechanical engineering and related fields for later research.

  6. Summary of Research 1998, Department of Mechanical Engineering

    OpenAIRE

    Faculty of the Department of Mechanical Engineering, Naval Postgraduate School

    1998-01-01

    "The views expressed in this report are those of the authors and do not reflect the official policy or position of the Department of Defense or the U. S. Government. This report contains summaries of research projects in the Department of Mechanical Engineering. A list of recent publications is also included which consists of conference presentations and publications, books, contributions to books, published journal papers, technical reports, and thesis abstracts.

  7. Summary of Research 1996, Department of Mechanical Engineering

    OpenAIRE

    Faculty of the Department of Mechanical Engineering, Naval Postgraduate School

    1996-01-01

    The views expressed in this report are those of the authors and do not reflect the official policy or position of the Department of Defense or the U.S. Government. This report contains summaries of research projects in the Department of Mechanical Engineering. A list of recent publications is also included which consists of conference presentations and publications, books, contributions to books, published journal papers, technical reports, and thesis abstracts.

  8. Development of mechanical engineering curricula at the University of Minho

    OpenAIRE

    J. C. F. Teixeira; Silva, Jaime F. da; Flores, Paulo

    2007-01-01

    The implementation of the Bologna protocol in the European Union has set new goals for the whole higher education system as: (a) a quality assessment for university courses; (b) a framework for the exchange of students and academics; and (c) an opportunity for changing the teaching/learning procedures and methodologies. Within the context, the mechanical engineering curricula at the University of Minho have been comprehensively formulated in order to meet these and future challenges and expec...

  9. The Molecular Mechanisms and the Role of hnRNP K Protein Post- Translational Modification in DNA Damage Repair.

    Science.gov (United States)

    Lu, Jing; Gao, Feng-Hou

    2017-01-01

    DNA damage repair is a kind of cellular self-protection mechanism in which some relevant proteins are activated when DNA damage response occurs in order to maintain the intracellular function stability and structure integrity. Post-translational modifications (PTMs) of proteins can rapidly confer to them more complicated structure and sophisticated function by covalently combining different small molecules with target proteins, which in turn plays an important regulatory role in DNA damage repair. It was reported that heterogeneous nuclear ribonucleoprotein K (hnRNP K) could be involved in DNA damage repair process under the regulation of its many post-translational modifications, including methylation, ubiquitination, sumoylation and phosphorylation. Here, we reviewed molecular mechanisms of hnRNP K protein post-translational modifications and their role in DNA damage repair, which will promote our understanding of how hnRNP K participating in the repair process to maintain the normal operation of biological activities in the cells. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  10. Development of repair mechanism of FSX-414 based 1st stage nozzle of gas turbine

    Science.gov (United States)

    Rahman, Md. Tawfiqur

    2017-06-01

    This paper describes the failure mechanism and repair technology of 1st stage nozzle or vane of industrial gas turbine which is made of cobalt based super alloy FSX-414. 1st stage nozzles or vanes are important stationery components of gas turbine based power plant. Those are the parts of hot gas path components of gas turbine and their manufacturing process is casting. At present, it is widely accepted that gas turbine based combined cycle power plant is the most efficient and cost effective solution to generate electricity. One of the factors of high efficiency of this type of gas turbine is the increase of its turbine inlet temperature. As an effect of this factor and in conjunction with some other factors, the 1st stage nozzle of gas turbine operates under extremely high temperature and thermal stresses. As a result, the design lifetime of these components becomes limited. Furthermore, attention on nozzles or vanes is required in order to achieve their design lifetime. However, due to unfriendly operational condition and environmental effect, anytime failure can occur on these heat resistant alloy based components which may lead to severe damage of gas turbine. To mitigate these adverse effects, schedule maintenance is performed on a predetermined time interval of hot gas path components of gas turbine based power plant. This paper addresses common failures in gas turbine's 1st stage nozzles or vanes. Usually these are repaired by using ADH process but for several reasons ADH process is not used here. Hence the challenging task is performed using gas tungsten arc welding which is presented in this article systematically.

  11. Channelled scaffolds for engineering myocardium with mechanical stimulation.

    Science.gov (United States)

    Zhang, Ting; Wan, Leo Q; Xiong, Zhuo; Marsano, Anna; Maidhof, Robert; Park, Miri; Yan, Yongnian; Vunjak-Novakovic, Gordana

    2012-10-01

    The characteristics of the matrix (composition, structure, mechanical properties) and external culture environment (pulsatile perfusion, physical stimulation) of the heart are important characteristics in the engineering of functional myocardial tissue. This study reports on the development of chitosan-collagen scaffolds with micropores and an array of parallel channels (~ 200 µm in diameter) that were specifically designed for cardiac tissue engineering using mechanical stimulation. The scaffolds were designed to have similar structural and mechanical properties of those of native heart matrix. Scaffolds were seeded with neonatal rat heart cells and subjected to dynamic tensile stretch using a custom designed bioreactor. The channels enhanced oxygen transport and facilitated the establishment of cell connections within the construct. The myocardial patches (14 mm in diameter, 1-2 mm thick) consisted of metabolically active cells that began to contract synchronously after 3 days of culture. Mechanical stimulation with high tensile stress promoted cell alignment, elongation, and expression of connexin-43 (Cx-43). This study confirms the importance of scaffold design and mechanical stimulation for the formation of contractile cardiac constructs.

  12. Channeled Scaffolds for Engineering Myocardium with Mechanical Stimulation

    Science.gov (United States)

    Zhang, Ting; Wan, Leo Q.; Xiong, Zhuo; Marsano, Anna; Maidhof, Robert; Park, Miri; Yan, Yongnian; Vunjak-Novakovic, Gordana

    2011-01-01

    The characteristics of the matrix (composition, structure, mechanical properties) and external culture environment (pulsatile perfusion, physical stimulation) are critically important for engineering functional myocardial tissue. We report the development of chitosan-collagen scaffolds with micro-pores and an array of parallel channels (~200 μm in diameter) that were specifically designed for cardiac tissue engineering with mechanical stimulation. The scaffolds were designed to have the structural and mechanical properties similar to those of the native human heart matrix. Scaffolds were seeded with neonatal rat heart cells and subjected to dynamic tensile stretch using a custom-designed bioreactor. The channels enhanced oxygen transport and facilitated the establishment of cell connections within the construct. The myocardial patches (14 mm in diameter, 1–2 mm thick) consisted of metabolically active cells and started to contract synchronously after 3 days of culture. Mechanical stimulation with high tensile stresses promoted cell alignment, elongation, and the expression of connexin-43 (Cx-43). This study confirms the importance of scaffold design and mechanical stimulation for the formation of contractile cardiac constructs. PMID:22081518

  13. Course Outline for Lesson Plans for Pre-Employment Laboratory Training in CVAE-VEH Farm and Ranch Mechanical Repair.

    Science.gov (United States)

    Texas A and M Univ., College Station. Vocational Instructional Services.

    This packet contains 88 lesson plans for a laboratory course in farm and ranch mechanical repair. The lesson plans are organized into six units covering the following topics: occupational information, construction and maintenance (safety, farm carpentry, farm water supply and sanitation, farm electricity, concrete), hot metal work (oxyacetylene…

  14. ENGINEERING CHARACTERISTICS AND ITS MECHANISM EXPLANATION OF VIBRATORY SYNCHRONIZATION TRANSMISSION

    Institute of Scientific and Technical Information of China (English)

    Xiong Wanli; Wen Bangchun; Duan Zhishan

    2004-01-01

    Vibratory synchronization transmission (VST) is a kind of special physical phenomenon in inertia vibra-tion mechanical systems.For an inertia vibration mechanical system driven by one pair of motors runs in step,even the power supply of one motor is cut off,the motor can continue to keep rotating state under the vibration exciting of the machine body driven by only one other motor.And its rotating frequency will be the same as that of the other one.The transient process of this wonderful physical phenomenon has not been described quantitatively according to current-existing mechanical models.On the basis of investigation of the engineering characteristics of VST,a mechanical and electrical coupling mathematical model of a two-shaft inertia vibration machine is established.With this model,the transient process of VST is recurred quantitatively and successfully,and a reasonable explana-tion is given.

  15. Reliability design of mechanical systems a guide for mechanical and civil engineers

    CERN Document Server

    Woo, Seongwoo

    2017-01-01

    This book describes basic reliability concepts – parametric ALT plan, failure mechanism and design, and reliability testing with acceleration factor and sample size equation. A generalized life-stress failure model with a new effort concept has been derived and recommended to calculate the acceleration factor of the mechanical system. The new sample size equation with the acceleration factor has also been derived to carry out the parametric ALT. This new parametric ALT should help a mechanical/civil engineer to uncover the design parameters affecting reliability during the design process of the mechanical system. Consequently, it should help companies to improve product reliability and avoid recalls due to the product/structure failures in the field. As the improper or missing design parameters in the design phase are experimentally identified by this new reliability design method - parametric ALT, the mechanical/civil engineering system might improve in reliability by the increase in lifetime and the reduc...

  16. 46 CFR 113.35-13 - Mechanical engine order telegraph systems; operation.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Mechanical engine order telegraph systems; operation...) ELECTRICAL ENGINEERING COMMUNICATION AND ALARM SYSTEMS AND EQUIPMENT Engine Order Telegraph Systems § 113.35-13 Mechanical engine order telegraph systems; operation. If more than one transmitter operates...

  17. Mechanical stimulation improves tissue-engineered human skeletal muscle

    Science.gov (United States)

    Powell, Courtney A.; Smiley, Beth L.; Mills, John; Vandenburgh, Herman H.

    2002-01-01

    Human bioartificial muscles (HBAMs) are tissue engineered by suspending muscle cells in collagen/MATRIGEL, casting in a silicone mold containing end attachment sites, and allowing the cells to differentiate for 8 to 16 days. The resulting HBAMs are representative of skeletal muscle in that they contain parallel arrays of postmitotic myofibers; however, they differ in many other morphological characteristics. To engineer improved HBAMs, i.e., more in vivo-like, we developed Mechanical Cell Stimulator (MCS) hardware to apply in vivo-like forces directly to the engineered tissue. A sensitive force transducer attached to the HBAM measured real-time, internally generated, as well as externally applied, forces. The muscle cells generated increasing internal forces during formation which were inhibitable with a cytoskeleton depolymerizer. Repetitive stretch/relaxation for 8 days increased the HBAM elasticity two- to threefold, mean myofiber diameter 12%, and myofiber area percent 40%. This system allows engineering of improved skeletal muscle analogs as well as a nondestructive method to determine passive force and viscoelastic properties of the resulting tissue.

  18. Mechanical stimulation improves tissue-engineered human skeletal muscle

    Science.gov (United States)

    Powell, Courtney A.; Smiley, Beth L.; Mills, John; Vandenburgh, Herman H.

    2002-01-01

    Human bioartificial muscles (HBAMs) are tissue engineered by suspending muscle cells in collagen/MATRIGEL, casting in a silicone mold containing end attachment sites, and allowing the cells to differentiate for 8 to 16 days. The resulting HBAMs are representative of skeletal muscle in that they contain parallel arrays of postmitotic myofibers; however, they differ in many other morphological characteristics. To engineer improved HBAMs, i.e., more in vivo-like, we developed Mechanical Cell Stimulator (MCS) hardware to apply in vivo-like forces directly to the engineered tissue. A sensitive force transducer attached to the HBAM measured real-time, internally generated, as well as externally applied, forces. The muscle cells generated increasing internal forces during formation which were inhibitable with a cytoskeleton depolymerizer. Repetitive stretch/relaxation for 8 days increased the HBAM elasticity two- to threefold, mean myofiber diameter 12%, and myofiber area percent 40%. This system allows engineering of improved skeletal muscle analogs as well as a nondestructive method to determine passive force and viscoelastic properties of the resulting tissue.

  19. Acoustics in mechanical engineering undergraduate core courses: Challenges and opportunities

    Science.gov (United States)

    Prasad, M. G.

    2005-04-01

    Generally in an undergraduate curriculum of mechanical engineering, acoustics is not included as a core course. The major core courses deal with mechanics, design, dynamics of machinery, etc. However, engineering aspects of acoustics or noise can be included through elective courses. Given the limited slots for elective courses in a curriculum, it is difficult to run elective courses in acoustics regularly with a required number of students. The challenge is to find innovative ways to include acoustics into core courses so that all students are exposed to the field and its applications. The design and analysis of machine elements such as cams, gears, etc. are always part of core courses. It is in these contexts that the acoustics through noise aspects including multimedia can be introduced. Acoustics as an effect due to vibration as cause can be included in vibration analysis. A core course on system modeling can include acoustics. The integration of acoustical topics not only strengthens the core courses but also prepares the graduating engineer to deal with real problems better. Thus, it is important for academic acousticians to bring acoustics into the core courses. This paper presents some efforts to include the acoustics material in some core courses.

  20. Introduction of a New Suture Method in Repair of Peripheral Nerves Injured with a Sharp Mechanism

    Directory of Open Access Journals (Sweden)

    Alireza Saied

    2015-09-01

    Full Text Available Background: The standard method for repair of an injured peripheal nerve is epineural repair with separate sutures. Herein we describe a method in which the nerve is sutured with continous sutures. In fact this method has not been utilized for nerve repair previously and our purpose was to compare it to the standard method. If it proved to be successful it would replace the standard method in certain circumstances. Methods: The proposal of the clinical trial was given a reference number form the ethics comitee. 25 dogs in which the scaitic nerve was cut by a sharp blade under genaeral anesthesia were divided randomly into three groups: control (5 dogs, repair of sciatic nerve with simple sutures (10 and repair with continous sutures (10. In the control group the nerve was not repaired at all. After 6 weeks the dogs were killed and the nerve was studied by light and electronic microscopes. The amount of consumed suture material, time of repair, myelin thickness and axon diiameter were examined. Ultrastructural studies were performed to assess degeneration and regeneration findings. Results: Time of repair and the amount of consumed suture material were significantly lower in the continous group (P

  1. Thermoplastics as engineering materials: The mechanics, materials, design, processing link

    Energy Technology Data Exchange (ETDEWEB)

    Stokes, V.K. [GE Corporate Research and Development, Schenectady, NY (United States). Engineering Mechanics Lab.

    1995-10-01

    While the use of plastics has been growing at a significant pace because of weight reduction, ease of fabrication of complex shapes, and cost reduction resulting from function integration, the engineering applications of plastics have only become important in the past fifteen years. An inadequate understanding of the mechanics issues underlying the close coupling among the design, the processing (fabrication), and the assembly with these materials is a barrier to their use in structural applications. Recent progress on some issues relating to the engineering uses of plastics is surveyed, highlighting the need for a better understanding of plastics and how processing affects the performance of plastic parts. Topics addressed include the large deformation behavior of ductile resins, fiber orientation in chopped-fiber filled materials, structural foams, random glass mat composites, modeling of thickness distributions in blow-molded and thermoformed parts, dimensional stability (shrinkage, warpage, and residual stresses) in injection-molded parts, and welding of thermoplastics.

  2. Credible Mechanism for More Reliable SearchEngine Results

    Directory of Open Access Journals (Sweden)

    Mohammed Abdel Razek

    2015-02-01

    Full Text Available the number of websites on the Internet is growing randomly, thanks to HTML language. Consequently, a diversity of information is available on the Web, however, sometimes the content of it may be neither valuable nor trusted. This leads to a problem of a credibility of the existing information on these Websites. This paper investigates aspects affecting on the Websites credibility and then uses them along with dominant meaning of the query for improving information retrieval capabilities and to effectively manage contents. It presents a design and development of a credible mechanism that searches Web search engine and then ranks sites according to its reliability. Our experiments show that the credibility terms on the Websites can affect the ranking of the Web search engine and greatly improves retrieval effectiveness.

  3. Influence of internship toward entrepreneurship interest for mechanical engineering students

    Science.gov (United States)

    Sunyoto, Nugroho, Agus; Ulum, Miftakhul

    2017-03-01

    This study was aimed to determine the influence of internship toward students' entrepreneurship interest. Mechanical Engineering Education students from 2013 Batch who had the internship from Engineering Faculty at Semarang State University are the subject of this study. Data was collected through questionnaire and analyzed by simple regression analysis method. The internship subject score and entrepreneurship are categorized in very good level in which the average is 87.08% and 85.61%. However, the influence of internship toward students' interest is categorized in low level in which the average score is 7.9%. Internship section shall encourage students to study entrepreneurship aspects during the internship for entrepreneurship interest improvement and the students' preparation once they graduated. Description scoring standard is needed for scoring the students although they conduct their internship at different locations and companies. The students are highly recommended to conduct an an internship at entrepreneurship-based companies.

  4. The use of Statistical Methods in Mechanical Engineering

    Directory of Open Access Journals (Sweden)

    Iram Saleem

    2013-03-01

    Full Text Available Statistics is an important tool to handle the vast data of present era as statistics can interpret all the information in such a beauty that so many conclusions can be extracted from it. The aim of this study is to see the use of statistical methods in Mechanical Engineering (ME therefore; we selected research papers published in 2010 from the well reputed journals in ME under Taylor and Francis Company LTD. More than 350 research papers were downloaded from well reputed ME journals such as Inverse Problem in Science and Engineering (IPSE, Machining Science and Technology (MST, Materials and Manufacturing Processes (MMP, Particulate Science and Technology (PST and Research in Nondestructive Evaluation (RNE. We recorded the statistical techniques/methods used in each research paper. In this study, we presented frequency distribution of descriptive statistics and advance level statistical methods used in five of the ME journals in 2010.

  5. A real CDIO mechanical engineering project in 4th semester

    DEFF Research Database (Denmark)

    Lauritsen, Aage Birkkjær

    In the past 6 years at the mechanical engineering study at the Engineering College of Aarhus we have been practicing project work on 4th Semester in the design of energy technology systems. In my presentation, I will give a description of the project, and the thoughts behind; pedagogic......-6 students, and will partly support the general theory being taught in the courses, but will also provide students with skills in teamwork, project work and system building. The pedagogical considerations behind the development of the project are quite simply that students learn best through active work...... the components as parts of a complex system. The semester project design is developed on basis of these considerations. The semester consists of 4 theory courses in: thermodynamics, control- and simulation of dynamic systems, electronics and hydraulic systems. The project work is performed in groups of 4...

  6. Mechanics and model-based control of advanced engineering systems

    CERN Document Server

    Irschik, Hans; Krommer, Michael

    2014-01-01

    Mechanics and Model-Based Control of Advanced Engineering Systems collects 32 contributions presented at the International Workshop on Advanced Dynamics and Model Based Control of Structures and Machines, which took place in St. Petersburg, Russia in July 2012. The workshop continued a series of international workshops, which started with a Japan-Austria Joint Workshop on Mechanics and Model Based Control of Smart Materials and Structures and a Russia-Austria Joint Workshop on Advanced Dynamics and Model Based Control of Structures and Machines. In the present volume, 10 full-length papers based on presentations from Russia, 9 from Austria, 8 from Japan, 3 from Italy, one from Germany and one from Taiwan are included, which represent the state of the art in the field of mechanics and model based control, with particular emphasis on the application of advanced structures and machines.

  7. Mechanical Stress Changes the Complex Interplay Between HO-1, Inflammation and Fibrosis, During Excisional Wound Repair

    Science.gov (United States)

    Cremers, Niels A. J.; Suttorp, Maarten; Gerritsen, Marlous M.; Wong, Ronald J.; van Run-van Breda, Coby; van Dam, Gooitzen M.; Brouwer, Katrien M.; Kuijpers-Jagtman, Anne Marie; Carels, Carine E. L.; Lundvig, Ditte M. S.; Wagener, Frank A. D. T. G.

    2015-01-01

    Mechanical stress following surgery or injury can promote pathological wound healing and fibrosis, and lead to functional loss and esthetic problems. Splinted excisional wounds can be used as a model for inducing mechanical stress. The cytoprotective enzyme heme oxygenase-1 (HO-1) is thought to orchestrate the defense against inflammatory and oxidative insults that drive fibrosis. Here, we investigated the activation of the HO-1 system in a splinted and non-splinted full-thickness excisional wound model using HO-1-luc transgenic mice. Effects of splinting on wound closure, HO-1 promoter activity, and markers of inflammation and fibrosis were assessed. After seven days, splinted wounds were more than three times larger than non-splinted wounds, demonstrating a delay in wound closure. HO-1 promoter activity rapidly decreased following removal of the (epi)dermis, but was induced in both splinted and non-splinted wounds during skin repair. Splinting induced more HO-1 gene expression in 7-day wounds; however, HO-1 protein expression remained lower in the epidermis, likely due to lower numbers of keratinocytes in the re-epithelialization tissue. Higher numbers of F4/80-positive macrophages, αSMA-positive myofibroblasts, and increased levels of the inflammatory genes IL-1β, TNF-α, and COX-2 were present in 7-day splinted wounds. Surprisingly, mRNA expression of newly formed collagen (type III) was lower in 7-day wounds after splinting, whereas, VEGF and MMP-9 were increased. In summary, these data demonstrate that splinting delays cutaneous wound closure and HO-1 protein induction. The pro-inflammatory environment following splinting may facilitate higher myofibroblast numbers and increase the risk of fibrosis and scar formation. Therefore, inducing HO-1 activity against mechanical stress-induced inflammation and fibrosis may be an interesting strategy to prevent negative effects of surgery on growth and function in patients with orofacial clefts or in patients with

  8. Engineering the mechanical and biological properties of nanofibrous vascular grafts for in situ vascular tissue engineering.

    Science.gov (United States)

    Henry, Jeffrey J D; Yu, Jian; Wang, Aijun; Lee, Randall; Fang, Jun; Li, Song

    2017-08-17

    Synthetic small diameter vascular grafts have a high failure rate, and endothelialization is critical for preventing thrombosis and graft occlusion. A promising approach is in situ tissue engineering, whereby an acellular scaffold is implanted and provides stimulatory cues to guide the in situ remodeling into a functional blood vessel. An ideal scaffold should have sufficient binding sites for biomolecule immobilization and a mechanical property similar to native tissue. Here we developed a novel method to blend low molecular weight (LMW) elastic polymer during electrospinning process to increase conjugation sites and to improve the mechanical property of vascular grafts. LMW elastic polymer improved the elasticity of the scaffolds, and significantly increased the amount of heparin conjugated to the micro/nanofibrous scaffolds, which in turn increased the loading capacity of vascular endothelial growth factor (VEGF) and prolonged the release of VEGF. Vascular grafts were implanted into the carotid artery of rats to evaluate the in vivo performance. VEGF treatment significantly enhanced endothelium formation and the overall patency of vascular grafts. Heparin coating also increased cell infiltration into the electrospun grafts, thus increasing the production of collagen and elastin within the graft wall. This work demonstrates that LMW elastic polymer blending is an approach to engineer the mechanical and biological property of micro/nanofibrous vascular grafts for in situ vascular tissue engineering.

  9. Direct Mechanical Stimulation of Stem Cells: A Beating Electromechanically Active Scaffold for Cardiac Tissue Engineering.

    Science.gov (United States)

    Gelmi, Amy; Cieslar-Pobuda, Artur; de Muinck, Ebo; Los, Marek; Rafat, Mehrdad; Jager, Edwin W H

    2016-06-01

    The combination of stem cell therapy with a supportive scaffold is a promising approach to improving cardiac tissue engineering. Stem cell therapy can be used to repair nonfunctioning heart tissue and achieve myocardial regeneration, and scaffold materials can be utilized in order to successfully deliver and support stem cells in vivo. Current research describes passive scaffold materials; here an electroactive scaffold that provides electrical, mechanical, and topographical cues to induced human pluripotent stem cells (iPS) is presented. The poly(lactic-co-glycolic acid) fiber scaffold coated with conductive polymer polypyrrole (PPy) is capable of delivering direct electrical and mechanical stimulation to the iPS. The electroactive scaffolds demonstrate no cytotoxic effects on the iPS as well as an increased expression of cardiac markers for both stimulated and unstimulated protocols. This study demonstrates the first application of PPy as a supportive electroactive material for iPS and the first development of a fiber scaffold capable of dynamic mechanical actuation.

  10. 78 FR 37885 - Approval of American Society of Mechanical Engineers' Code Cases

    Science.gov (United States)

    2013-06-24

    ... Mechanical Engineers' Code Cases; Proposed Rule #0;#0;Federal Register / Vol. 78, No. 121 / Monday, June 24... American Society of Mechanical Engineers' Code Cases AGENCY: Nuclear Regulatory Commission. ACTION... revised Code Cases published by the American Society of Mechanical Engineers (ASME). This proposed...

  11. Mechanical cues in orofacial tissue engineering and regenerative medicine.

    Science.gov (United States)

    Brouwer, Katrien M; Lundvig, Ditte M S; Middelkoop, Esther; Wagener, Frank A D T G; Von den Hoff, Johannes W

    2015-01-01

    Cleft lip and palate patients suffer from functional, aesthetical, and psychosocial problems due to suboptimal regeneration of skin, mucosa, and skeletal muscle after restorative cleft surgery. The field of tissue engineering and regenerative medicine (TE/RM) aims to restore the normal physiology of tissues and organs in conditions such as birth defects or after injury. A crucial factor in cell differentiation, tissue formation, and tissue function is mechanical strain. Regardless of this, mechanical cues are not yet widely used in TE/RM. The effects of mechanical stimulation on cells are not straight-forward in vitro as cellular responses may differ with cell type and loading regime, complicating the translation to a therapeutic protocol. We here give an overview of the different types of mechanical strain that act on cells and tissues and discuss the effects on muscle, and skin and mucosa. We conclude that presently, sufficient knowledge is lacking to reproducibly implement external mechanical loading in TE/RM approaches. Mechanical cues can be applied in TE/RM by fine-tuning the stiffness and architecture of the constructs to guide the differentiation of the seeded cells or the invading surrounding cells. This may already improve the treatment of orofacial clefts and other disorders affecting soft tissues.

  12. Human umbilical cord mesenchymal stem cells promote peripheral nerve repair via paracrine mechanisms

    Directory of Open Access Journals (Sweden)

    Zhi-yuan Guo

    2015-01-01

    Full Text Available Human umbilical cord-derived mesenchymal stem cells (hUCMSCs represent a promising young-state stem cell source for cell-based therapy. hUCMSC transplantation into the transected sciatic nerve promotes axonal regeneration and functional recovery. To further clarify the paracrine effects of hUCMSCs on nerve regeneration, we performed human cytokine antibody array analysis, which revealed that hUCMSCs express 14 important neurotrophic factors. Enzyme-linked immunosorbent assay and immunohistochemistry showed that brain-derived neurotrophic factor, glial-derived neurotrophic factor, hepatocyte growth factor, neurotrophin-3, basic fibroblast growth factor, type I collagen, fibronectin and laminin were highly expressed. Treatment with hUCMSC-conditioned medium enhanced Schwann cell viability and proliferation, increased nerve growth factor and brain-derived neurotrophic factor expression in Schwann cells, and enhanced neurite growth from dorsal root ganglion explants. These findings suggest that paracrine action may be a key mechanism underlying the effects of hUCMSCs in peripheral nerve repair.

  13. Rapid Identification of Chemoresistance Mechanisms Using Yeast DNA Mismatch Repair Mutants.

    Science.gov (United States)

    Ojini, Irene; Gammie, Alison

    2015-07-21

    Resistance to cancer therapy is a major obstacle in the long-term treatment of cancer. A greater understanding of drug resistance mechanisms will ultimately lead to the development of effective therapeutic strategies to prevent resistance from occurring. Here, we exploit the mutator phenotype of mismatch repair defective yeast cells combined with whole genome sequencing to identify drug resistance mutations in key pathways involved in the development of chemoresistance. The utility of this approach was demonstrated via the identification of the known CAN1 and TOP1 resistance targets for two compounds, canavanine and camptothecin, respectively. We have also experimentally validated the plasma membrane transporter HNM1 as the primary drug resistance target of mechlorethamine. Furthermore, the sequencing of mitoxantrone-resistant strains identified inactivating mutations within IPT1, a gene encoding inositolphosphotransferase, an enzyme involved in sphingolipid biosynthesis. In the case of bactobolin, a promising anticancer drug, the endocytosis pathway was identified as the drug resistance target responsible for conferring resistance. Finally, we show that that rapamycin, an mTOR inhibitor previously shown to alter the fitness of the ipt1 mutant, can effectively prevent the formation of mitoxantrone resistance. The rapid and robust nature of these techniques, using Saccharomyces cerevisiae as a model organism, should accelerate the identification of drug resistance targets and guide the development of novel therapeutic combination strategies to prevent the development of chemoresistance in various cancers.

  14. Mechanical evaluation of gradient electrospun scaffolds with 3D printed ring reinforcements for tracheal defect repair.

    Science.gov (United States)

    Ott, Lindsey M; Zabel, Taylor A; Walker, Natalie K; Farris, Ashley L; Chakroff, Jason T; Ohst, Devan G; Johnson, Jed K; Gehrke, Steven H; Weatherly, Robert A; Detamore, Michael S

    2016-04-21

    Tracheal stenosis can become a fatal condition, and current treatments include augmentation of the airway with autologous tissue. A tissue-engineered approach would not require a donor source, while providing an implant that meets both surgeons' and patients' needs. A fibrous, polymeric scaffold organized in gradient bilayers of polycaprolactone (PCL) and poly-lactic-co-glycolic acid (PLGA) with 3D printed structural ring supports, inspired by the native trachea rings, could meet this need. The purpose of the current study was to characterize the tracheal scaffolds with mechanical testing models to determine the design most suitable for maintaining a patent airway. Degradation over 12 weeks revealed that scaffolds with the 3D printed rings had superior properties in tensile and radial compression, with at least a three fold improvement and 8.5-fold improvement, respectively, relative to the other scaffold groups. The ringed scaffolds produced tensile moduli, radial compressive forces, and burst pressures similar to or exceeding physiological forces and native tissue data. Scaffolds with a thicker PCL component had better suture retention and tube flattening recovery properties, with the monolayer of PCL (PCL-only group) exhibiting a 2.3-fold increase in suture retention strength (SRS). Tracheal scaffolds with ring reinforcements have improved mechanical properties, while the fibrous component increased porosity and cell infiltration potential. These scaffolds may be used to treat various trachea defects (patch or circumferential) and have the potential to be employed in other tissue engineering applications.

  15. Mechanisms Engineering Test Loop - Phase 1 Status Report

    Energy Technology Data Exchange (ETDEWEB)

    Kultgen, D. [Argonne National Lab. (ANL), Argonne, IL (United States); Grandy, C. [Argonne National Lab. (ANL), Argonne, IL (United States); Hvasta, M. [Argonne National Lab. (ANL), Argonne, IL (United States); Lisowski, D. [Argonne National Lab. (ANL), Argonne, IL (United States); Toter, W. [Argonne National Lab. (ANL), Argonne, IL (United States); Borowski, A. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-09-01

    This report documents the current status of the Mechanisms Engineering Test Loop (METL) as of the end of FY2016. Currently, METL is in Phase I of its design and construction. Once operational, the METL facility will test small to intermediate-scale components and systems in order to develop advanced liquid metal technologies. Testing different components in METL is essential for the future of advanced fast reactors as it will provide invaluable performance data and reduce the risk of failures during plant operation.

  16. APPROACH TO MANAGEMENT PERSONNEL AT MECHANICAL ENGINEERING ENTERPRISES

    Directory of Open Access Journals (Sweden)

    Sogomonyan T. K.

    2015-11-01

    Full Text Available The article considers the existing at the present stage of management approaches, describes their advantages and disadvantages. We have obtained scientific and special management approaches. Of all the approaches described in detail, we could highlight system, integration, dynamic, structural, functional and process approaches. It was indicated, that the use of the above approach to production management, as a whole, and the staff in particular - is limited to the economic sphere of activity, meanwhile, as there is a prospect of using these approaches in the field of labor protection. We also substantiate the choice process approach as the most promising in the management staff of mechanical engineering enterprise

  17. Effect of Mechanical Surface Treatment on the Repair Bond Strength of the Silorane-based Composite Resin

    Directory of Open Access Journals (Sweden)

    Parnian Alizadeh Oskoee

    2014-06-01

    Full Text Available Background and aims. A proper bond must be created between the existing composite resin and the new one for successful repair. The aim of this study was to compare the effect of three mechanical surface treatments, using diamond bur, air abrasion, and Er,Cr:YSGG laser, on the repair bond strength of the silorane-based composite resin. Materials and methods. Sixty cylindrical composite resin specimens (Filtek Silorane were fabricated and randomly divided into four groups according to surface treatment: group 1 (control group without any mechanical surface treatment, groups 24 were treated with air abrasion, Er,Cr:YSGG laser, and diamond bur, respectively. In addition, a positive control group was assigned in order to measure the cohesive strength. Silorane bonding agent was used in groups 14 before adding the new composite resin. Then, the specimens were subjected to a shear bond strength test and data was analyzed using one-way ANOVA and post hoc Tukey tests at a significance level of P < 0.05. The topographical effects of surface treatments were characterized under a scanning electron microscope. Results. There were statistically significant differences in the repair bond strength values between groups 1 and 2 and groups 3 and 4 (P < 0.001. There were no significant differences between groups 1 and 2 (P = 0.98 and groups 3 and 4 (P = 0.97. Conclusion. Surface treatment using Er,Cr:YSGG laser and diamond bur were effective in silorane-based composite resin repair.

  18. Cumulative asbestos exposure for US automobile mechanics involved in brake repair (circa 1950s-2000).

    Science.gov (United States)

    Finley, Brent L; Richter, Richard O; Mowat, Fionna S; Mlynarek, Steve; Paustenbach, Dennis J; Warmerdam, John M; Sheehan, Patrick J

    2007-11-01

    We analyzed cumulative lifetime exposure to chrysotile asbestos experienced by brake mechanics in the US during the period 1950-2000. Using Monte Carlo methods, cumulative exposures were calculated using the distribution of 8-h time-weighted average exposure concentrations for brake mechanics and the distribution of job tenure data for automobile mechanics. The median estimated cumulative exposures for these mechanics, as predicted by three probabilistic models, ranged from 0.16 to 0.41 fibers per cubic centimeter (f/cm(3)) year for facilities with no dust-control procedures (1970s), and from 0.010 to 0.012 f/cm(3) year for those employing engineering controls (1980s). Upper-bound (95%) estimates for the 1970s and 1980s were 1.96 to 2.79 and 0.07-0.10 f/cm(3) year, respectively. These estimates for US brake mechanics are consistent with, but generally slightly lower than, those reported for European mechanics. The values are all substantially lower than the cumulative exposure of 4.5 f/cm(3) year associated with occupational exposure to 0.1 f/cm(3) of asbestos for 45 years that is currently permitted under the current occupational exposure limits in the US. Cumulative exposures were usually about 100- to 1,000-fold less than those of other occupational groups with asbestos exposure for similar time periods. The cumulative lifetime exposure estimates presented here, combined with the negative epidemiology data for brake mechanics, could be used to refine the risk assessments for chrysotile-exposed populations.

  19. Collagen based film with well epithelial and stromal regeneration as corneal repair materials: Improving mechanical property by crosslinking with citric acid

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Xuan; Liu, Yang; Li, Weichang; Long, Kai; Wang, Lin; Liu, Sa; Wang, Yingjun [School of Materials Science and Engineering, South China University of Technology, Guangzhou (China); National Engineering Research Center for Tissue Restoration and Reconstruction, Guangzhou (China); Ren, Li, E-mail: psliren@scut.edu.cn [School of Materials Science and Engineering, South China University of Technology, Guangzhou (China); National Engineering Research Center for Tissue Restoration and Reconstruction, Guangzhou (China)

    2015-10-01

    Corneal disease can lead to vision loss. It has become the second greatest cause of blindness in the world, and keratoplasty is considered as an effective treatment method. This paper presents the crosslinked collagen (Col)–citric acid (CA) films developed by making use of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) and N-hydroxysuccinimide (NHS). The results showed that the Col–CA films had necessary optical performance, water content. The collagenase resistance of CA crosslinked films was superior to that of EDC crosslinked films. And CA5 film (Col:CA:EDC:NHS = 60:3:10:10) had the best mechanical properties. Cell experiments showed that CA5 film was non-cytotoxic and human corneal epithelial cells could proliferate well on the films. Lamellar keratoplasty showed that the CA5 film could be sutured in the rabbit eyes and was epithelialized completely in about 10 days, and the transparency was restored quickly in 30 ± 5 days. No inflammation and corneal neovascularization were observed at 6 months. Corneal stroma had been repaired; stromal cells and neo-stroma could be seen in the area of operation from the hematoxylin–eosin stained histologic sections and anterior segment optical coherence tomography images. These results indicated that Col–CA films were highly promising biomaterials that could be used in corneal tissue engineering and a variety of other tissue engineering applications. - Highlights: • Adding different amounts of citric acid could change the properties of films. • The crosslinked films had better mechanical property than non-modified films. • Crosslinked collagen–citric acid films could tolerate suture during operation. • The films showed good ability of epithelial and stromal repair.

  20. Horizontal gene transfer regulation in bacteria as a "spandrel" of DNA repair mechanisms.

    Directory of Open Access Journals (Sweden)

    Saliou Fall

    might have led the bacteria to hijack DNA repair mechanisms in order to generate genetic diversity without losing too much genomic stability.

  1. Protecting DNA from errors and damage: an overview of DNA repair mechanisms in plants compared to mammals.

    Science.gov (United States)

    Spampinato, Claudia P

    2017-05-01

    The genome integrity of all organisms is constantly threatened by replication errors and DNA damage arising from endogenous and exogenous sources. Such base pair anomalies must be accurately repaired to prevent mutagenesis and/or lethality. Thus, it is not surprising that cells have evolved multiple and partially overlapping DNA repair pathways to correct specific types of DNA errors and lesions. Great progress in unraveling these repair mechanisms at the molecular level has been made by several talented researchers, among them Tomas Lindahl, Aziz Sancar, and Paul Modrich, all three Nobel laureates in Chemistry for 2015. Much of this knowledge comes from studies performed in bacteria, yeast, and mammals and has impacted research in plant systems. Two plant features should be mentioned. Plants differ from higher eukaryotes in that they lack a reserve germline and cannot avoid environmental stresses. Therefore, plants have evolved different strategies to sustain genome fidelity through generations and continuous exposure to genotoxic stresses. These strategies include the presence of unique or multiple paralogous genes with partially overlapping DNA repair activities. Yet, in spite (or because) of these differences, plants, especially Arabidopsis thaliana, can be used as a model organism for functional studies. Some advantages of this model system are worth mentioning: short life cycle, availability of both homozygous and heterozygous lines for many genes, plant transformation techniques, tissue culture methods and reporter systems for gene expression and function studies. Here, I provide a current understanding of DNA repair genes in plants, with a special focus on A. thaliana. It is expected that this review will be a valuable resource for future functional studies in the DNA repair field, both in plants and animals.

  2. Mechanical characteristics of native tendon slices for tissue engineering scaffold

    Science.gov (United States)

    Qin, Ting-Wu; Chen, Qingshan; Sun, Yu-Long; Steinmann, Scott P.; Amadio, Peter C.; An, Kai-Nan; Zhao, Chunfeng

    2014-01-01

    The purpose of this study was to characterize the mechanical behavior of tendon slices with different thicknesses. Tendon slices of 100, 200, 300, 400, and 500 μm thickness were mechanically tested. The 300 μm slices were further tested for strength and modulus after 21,000-cycle fatigue testing under different applied strain levels (0, 1, 3, 5, 8, 10, and 12%). The tendon slice structure, morphology, and viability of bone marrow stromal cells (BMSCs) seeded onto the slices were also examined with histology, scanning electron microscopy, and vital cell labeling, respectively. Tendon slices 300 μm or more in thickness had similar ultimate tensile strength and Young's modulus to the intact tendon bundle. A strain of 5% or less did not cause any structural damage, nor did it change the mechanical properties of a 300 μm-thick tendon slice after 21,000-cycle fatigue testing. BMSCs were viable between and on the tendon slices after 2 weeks in tissue culture. This study demonstrated that, if tendon slices are used as a scaffold for tendon tissue engineering, slices 300 μm or more in thickness would be preferable from a mechanical strength point of view. If mechanical stimulation is performed for seeded-cell preparations, 5% strain or less would be appropriate. PMID:22323314

  3. Mechanical characteristics of native tendon slices for tissue engineering scaffold.

    Science.gov (United States)

    Qin, Ting-Wu; Chen, Qingshan; Sun, Yu-Long; Steinmann, Scott P; Amadio, Peter C; An, Kai-Nan; Zhao, Chunfeng

    2012-04-01

    The purpose of this study was to characterize the mechanical behavior of tendon slices with different thicknesses. Tendon slices of 100, 200, 300, 400, and 500 μm thickness were mechanically tested. The 300 μm slices were further tested for strength and modulus after 21,000-cycle fatigue testing under different applied strain levels (0, 1, 3, 5, 8, 10, and 12%). The tendon slice structure, morphology, and viability of bone marrow stromal cells (BMSCs) seeded onto the slices were also examined with histology, scanning electron microscopy, and vital cell labeling, respectively. Tendon slices 300 μm or more in thickness had similar ultimate tensile strength and Young's modulus to the intact tendon bundle. A strain of 5% or less did not cause any structural damage, nor did it change the mechanical properties of a 300 μm-thick tendon slice after 21,000-cycle fatigue testing. BMSCs were viable between and on the tendon slices after 2 weeks in tissue culture. This study demonstrated that, if tendon slices are used as a scaffold for tendon tissue engineering, slices 300 μm or more in thickness would be preferable from a mechanical strength point of view. If mechanical stimulation is performed for seeded-cell preparations, 5% strain or less would be appropriate.

  4. Cardan gear mechanism versus slider-crank mechanism in pumps and engines

    Energy Technology Data Exchange (ETDEWEB)

    Karhula, J.

    2008-07-01

    In machine design we always want to save space, save energy and produce as much power as possible. We can often reduce accelerations, inertial loads and energy consumption by changing construction. In this study the old cardan gear mechanism (hypocycloid mechanism) has been compared with the conventional slider-crank mechanism in air pumps and four-stroke engines. Comprehensive Newtonian dynamics has been derived for the both mechanisms. First the slidercrank and the cardan gear machines have been studied as lossless systems. Then the friction losses have been added to the calculations. The calculation results show that the cardan gear machines can be more efficient than the slider-crank machines. The smooth running, low mass inertia, high pressures and small frictional power losses make the cardan gear machines clearly better than the slider-crank machines. The dynamic tooth loads of the original cardan gear construction do not rise very high when the tooth clearances are kept tight. On the other hand the half-size crank length causes high bearing forces in the cardan gear machines. The friction losses of the cardan gear machines are generally quite small. The mechanical efficiencies are much higher in the cardan gear machines than in the slider-crank machines in normal use. Crankshaft torques and power needs are smaller in the cardan gear air pumps than in the equal slider-crank air pumps. The mean crankshaft torque and the mean output power are higher in the cardan gear four-stroke engines than in the slider-crank four-stroke engines in normal use. The cardan gear mechanism is at its best, when we want to build a pump or an engine with a long connecting rod (approx 5.crank length) and a thin piston (approx 1.5.crank length) rotating at high angular velocity and intermittently high angular acceleration. The cardan gear machines can be designed also as slide constructions without gears. Suitable applications of the cardan gear machines are three-cylinder half

  5. Engineering mechanics of deformable solids a presentation with exercises

    CERN Document Server

    Govindjee, Sanjay

    2013-01-01

    This book covers the essential elements of engineering mechanics of deformable bodies, including mechanical elements in tension-compression, torsion, and bending. It emphasizes a fundamental bottom up approach to the subject in a concise and uncluttered presentation. Of special interest are chapters dealing with potential energy as well as principle of virtual work methods for both exact and approximate solutions. The book places an emphasis on the underlying assumptions of the theories in order to encourage the reader to think more deeply about the subject matter. The book should be of special interest to undergraduate students looking for a streamlined presentation as well as those returning to the subject for a second time.

  6. Design of a biaxial mechanical loading bioreactor for tissue engineering.

    Science.gov (United States)

    Bilgen, Bahar; Chu, Danielle; Stefani, Robert; Aaron, Roy K

    2013-04-25

    We designed a loading device that is capable of applying uniaxial or biaxial mechanical strain to a tissue engineered biocomposites fabricated for transplantation. While the device primarily functions as a bioreactor that mimics the native mechanical strains, it is also outfitted with a load cell for providing force feedback or mechanical testing of the constructs. The device subjects engineered cartilage constructs to biaxial mechanical loading with great precision of loading dose (amplitude and frequency) and is compact enough to fit inside a standard tissue culture incubator. It loads samples directly in a tissue culture plate, and multiple plate sizes are compatible with the system. The device has been designed using components manufactured for precision-guided laser applications. Bi-axial loading is accomplished by two orthogonal stages. The stages have a 50 mm travel range and are driven independently by stepper motor actuators, controlled by a closed-loop stepper motor driver that features micro-stepping capabilities, enabling step sizes of less than 50 nm. A polysulfone loading platen is coupled to the bi-axial moving platform. Movements of the stages are controlled by Thor-labs Advanced Positioning Technology (APT) software. The stepper motor driver is used with the software to adjust load parameters of frequency and amplitude of both shear and compression independently and simultaneously. Positional feedback is provided by linear optical encoders that have a bidirectional repeatability of 0.1 μm and a resolution of 20 nm, translating to a positional accuracy of less than 3 μm over the full 50 mm of travel. These encoders provide the necessary position feedback to the drive electronics to ensure true nanopositioning capabilities. In order to provide the force feedback to detect contact and evaluate loading responses, a precision miniature load cell is positioned between the loading platen and the moving platform. The load cell has high accuracies of 0

  7. Design of a Biaxial Mechanical Loading Bioreactor for Tissue Engineering

    Science.gov (United States)

    Bilgen, Bahar; Chu, Danielle; Stefani, Robert; Aaron, Roy K.

    2013-01-01

    We designed a loading device that is capable of applying uniaxial or biaxial mechanical strain to a tissue engineered biocomposites fabricated for transplantation. While the device primarily functions as a bioreactor that mimics the native mechanical strains, it is also outfitted with a load cell for providing force feedback or mechanical testing of the constructs. The device subjects engineered cartilage constructs to biaxial mechanical loading with great precision of loading dose (amplitude and frequency) and is compact enough to fit inside a standard tissue culture incubator. It loads samples directly in a tissue culture plate, and multiple plate sizes are compatible with the system. The device has been designed using components manufactured for precision-guided laser applications. Bi-axial loading is accomplished by two orthogonal stages. The stages have a 50 mm travel range and are driven independently by stepper motor actuators, controlled by a closed-loop stepper motor driver that features micro-stepping capabilities, enabling step sizes of less than 50 nm. A polysulfone loading platen is coupled to the bi-axial moving platform. Movements of the stages are controlled by Thor-labs Advanced Positioning Technology (APT) software. The stepper motor driver is used with the software to adjust load parameters of frequency and amplitude of both shear and compression independently and simultaneously. Positional feedback is provided by linear optical encoders that have a bidirectional repeatability of 0.1 μm and a resolution of 20 nm, translating to a positional accuracy of less than 3 μm over the full 50 mm of travel. These encoders provide the necessary position feedback to the drive electronics to ensure true nanopositioning capabilities. In order to provide the force feedback to detect contact and evaluate loading responses, a precision miniature load cell is positioned between the loading platen and the moving platform. The load cell has high accuracies of 0

  8. Alkylation damage in DNA and RNA--repair mechanisms and medical significance

    DEFF Research Database (Denmark)

    Drabløs, Finn; Feyzi, Emadoldin; Aas, Per Arne

    2004-01-01

    Alkylation lesions in DNA and RNA result from endogenous compounds, environmental agents and alkylating drugs. Simple methylating agents, e.g. methylnitrosourea, tobacco-specific nitrosamines and drugs like temozolomide or streptozotocin, form adducts at N- and O-atoms in DNA bases. These lesions...... are mainly repaired by direct base repair, base excision repair, and to some extent by nucleotide excision repair (NER). The identified carcinogenicity of O(6)-methylguanine (O(6)-meG) is largely caused by its miscoding properties. Mutations from this lesion are prevented by O(6)-alkylG-DNA alkyltransferase......, inactivation of the MMR system in an AGT-defective background causes resistance to the killing effects of O(6)-alkylating agents, but not to the mutagenic effect. Bifunctional alkylating agents, such as chlorambucil or carmustine (BCNU), are commonly used anti-cancer drugs. DNA lesions caused by these agents...

  9. Dynamics and Mechanism of Efficient DNA Repair Reviewed by Active-Site Mutants

    Science.gov (United States)

    Tan, Chuang; Liu, Zheyun; Li, Jiang; Guo, Xunmin; Wang, Lijuan; Zhong, Dongping

    2010-06-01

    Photolyases repair the UV-induced pyrimidine dimers in damage DNA via a photoreaction which includes a series of light-driven electron transfers between the two-electron-reduced flavin cofactor FADH^- and the dimer. We report here our systematic studies of the repair dynamics in E. coli photolyase with mutation of several active-site residues. With femtosecond resolution, we observed the significant change in the forward electron transfer from the excited FADH^- to the dimer and the back electron transfer from the repaired thymines by mutation of E274A, R226A, R342A, N378S and N378C. We also found that the mutation of E274A accelerates the bond-breaking of the thymine dimer. The dynamics changes are consistent with the quantum yield study of these mutants. These results suggest that the active-site residues play a significant role, structurally and chemically, in the DNA repair photocycle.

  10. Towards Increasing State Support Efficiency of Mechanical Engineering Plants

    Directory of Open Access Journals (Sweden)

    L. I. Kushnarev

    2016-01-01

    Full Text Available The article discusses a hot topic concerning the organization and implementation of a proprietary method of the technical service aimed at solving the problems of technological modernization of manufacturing facilities, machines and equipment and more efficient use of financial means allocated by the government of the Russian Federation for these purposes through increasing a level of competitiveness thanks to growing quality and reliability of equipment. Based on the analysis the paper gives an accent on the factors that are capable to provide a rate of return sufficient for additional, along with the state support, investments of innovative development of the enterprise because of technological modernization of production. Such an approach to technological modernization of mechanical engineering plants allows 3–5 times enhancement of their development rates provided that a careful scheduling of activities is based on the organizational and technological design. The researches have allowed us to formulate the proposals for the project implementation on innovative development of mechanical engineering.

  11. Interactive simulations as teaching tools for engineering mechanics courses

    Science.gov (United States)

    Carbonell, Victoria; Romero, Carlos; Martínez, Elvira; Flórez, Mercedes

    2013-07-01

    This study aimed to gauge the effect of interactive simulations in class as an active teaching strategy for a mechanics course. Engineering analysis and design often use the properties of planar sections in calculations. In the stress analysis of a beam under bending and torsional loads, cross-sectional properties are used to determine stress and displacement distributions in the beam cross section. The centroid, moments and products of inertia of an area made up of several common shapes (rectangles usually) may thus be obtained by adding the moments of inertia of the component areas (U-shape, L-shape, C-shape, etc). This procedure is used to calculate the second moments of structural shapes in engineering practice because the determination of their moments of inertia is necessary for the design of structural components. This paper presents examples of interactive simulations developed for teaching the ‘Mechanics and mechanisms’ course at the Universidad Politecnica de Madrid, Spain. The simulations focus on fundamental topics such as centroids, the properties of the moment of inertia, second moments of inertia with respect to two axes, principal moments of inertia and Mohr's Circle for plane stress, and were composed using Geogebra software. These learning tools feature animations, graphics and interactivity and were designed to encourage student participation and engagement in active learning activities, to effectively explain and illustrate course topics, and to build student problem-solving skills.

  12. Applying Best Practices to Military Commercial-Derivative Aircraft Engine Sustainment: Assessment of Using Parts Manufacturer Approval (PMA) Parts and Designated Engineering Representative (DER) Repairs

    Science.gov (United States)

    2016-01-01

    use of alter- nate part and repair sourcing would have required gathering and ana - lyzing data in several steps, shown below. In practice, we were...Parts and Repairs 47 DER repair parts lists from private-sector companies. We then ana - lyzed DLA distribution center data for quantities of NIINs...PMA Parts and DER Repairs Kendall, Frank , Under Secretary of Defense, Acquisition, Technology, and Logistics, “Better Buying Power: Guidance for

  13. DNA repair. [UV radiation

    Energy Technology Data Exchange (ETDEWEB)

    Setlow, R.

    1978-01-01

    Some topics discussed are as follows: difficulty in extrapolating data from E. coli to mammalian systems; mutations caused by UV-induced changes in DNA; mutants deficient in excision repair; other postreplication mechanisms; kinds of excision repair systems; detection of repair by biochemical or biophysical means; human mutants deficient in repair; mutagenic effects of UV on XP cells; and detection of UV-repair defects among XP individuals. (HLW)

  14. Progress in patch repair of aerospace composite structures

    Science.gov (United States)

    Hou, Weiguo; Zhang, Weifang; Tang, Qingyun

    2012-04-01

    With the rapid application of the composite structure in the aerospace industry, more load-bearing structures and components are used with composites instead of conventional engineering materials. However, the composite structures are inevitably suffered damages in the complex environment, the composites structures repair become more important in the airplane maintenance. This paper describes the composites patch repair progress. Firstly, the flaws and damages concerned to composite structures are concluded, and also the repair principles are presented. Secondly, the advantages and disadvantages for different repair methods are analyzed, as well as the different bonded repair and their applicability to different structures is discussed. According the recent research in theory and experiment, the scarf repair effects under different parameters are analyzed. Finally, the failure mechanisms of repair structure are discussed, and some prospects are put forward.

  15. Mechanical regulation of vascular network formation in engineered matrices.

    Science.gov (United States)

    Lesman, Ayelet; Rosenfeld, Dekel; Landau, Shira; Levenberg, Shulamit

    2016-01-15

    Generation of vessel networks within engineered tissues is critical for integration and perfusion of the implanted tissue in vivo. The effect of mechanical cues in guiding and stabilizing the vessels has begun to attract marked interest. This review surveys the impact of mechanical cues on formation of vascular networks in 2D and 3D gel matrices. We give less emphasis to regulation of endothelial monolayers and single endothelial cells. Several vascularization models have consistently found that the stress generated in the gel, and encountered by embedded cells, control various aspects of vascular network formation, including sprouting, branching, alignment, and vessel maturation. This internal stress is generated by cell contractile forces, and is balanced by gel stiffness and boundary constrains imposed on the gel. Actin and myosin II are key molecular players in controlling initiation of vessel sprouting and branching morphogenesis. Additionally, the impact of external mechanical cues on tissue vascularization, and studies supporting the notion that mechanical forces regulate vascularization in the live animal are reviewed.

  16. Novel mechanism of regulation of the DNA repair enzyme OGG1 in tuberin-deficient cells

    Science.gov (United States)

    Habib, Samy L.; Bhandari, Besant K.; Sadek, Nahed; Abboud-Werner, Sherry L.; Abboud, Hanna E.

    2010-01-01

    Tuberin (protein encodes by tuberous sclerosis complex 2, Tsc2) deficiency is associated with the decrease in the DNA repair enzyme 8-oxoG-DNA glycosylase (OGG1) in tumour kidney of tuberous sclerosis complex (TSC) patients. The purpose of this study was to elucidate the mechanisms by which tuberin regulates OGG1. The partial deficiency in tuberin expression that occurs in the renal proximal tubular cells and kidney cortex of the Eker rat is associated with decreased activator protein 4 (AP4) and OGG1 expression. A complete deficiency in tuberin is associated with loss of AP4 and OGG1 expression in kidney tumour from Eker rats and the accumulation of significant levels of 8-oxo-deoxyguanosine. Knockdown of tuberin expression in human renal epithelial cells (HEK293) with small interfering RNA (siRNA) also resulted in a marked decrease in the expression of AP4 and OGG1. In contrast, overexpression of tuberin in HEK293 cells increased the expression of AP4 and OGG1 proteins. Downregulation of AP4 expression using siRNA resulted in a significant decrease in the protein expression of OGG1. Immunoprecipitation studies show that AP4 is associated with tuberin in cells. Gel shift analysis and chromatin immunoprecipitation identified the transcription factor AP4 as a positive regulator of the OGG1 promoter. AP4 DNA-binding activity is significantly reduced in Tsc2−/− as compared with Tsc2+/+ cells. Transcriptional activity of the OGG1 promoter is also decreased in tuberin-null cells compared with wild-type cells. These data indicate a novel role for tuberin in the regulation of OGG1 through the transcription factor AP4. This regulation may be important in the pathogenesis of kidney tumours in patients with TSC disease. PMID:20837600

  17. Tissue engineering and the use of stem/progenitor cells for airway epithelium repair

    Directory of Open Access Journals (Sweden)

    GM Roomans

    2010-06-01

    Full Text Available Stem/progenitor cells can be used to repair defects in the airway wall, resulting from e.g., tumors, trauma, tissue reactions following long-time intubations, or diseases that are associated with epithelial damage. Several potential sources of cells for airway epithelium have been identified. These can be divided into two groups. The first group consists of endogenous progenitor cells present in the respiratory tract. This group can be subdivided according to location into (a a ductal cell type in the submucosal glands of the proximal trachea, (b basal cells in the intercartilaginous zones of the lower trachea and bronchi, (c variant Clara cells (Clarav-cells in the bronchioles and (d at the junctions between the bronchioles and the alveolar ducts, and (e alveolar type II cells. This classification of progenitor cell niches is, however, controversial. The second group consists of exogenous stem cells derived from other tissues in the body. This second group can be subdivided into: (a embryonic stem (ES cells, induced pluripotent stem (iPS cells, or amniotic fluid stem cells, (b side-population cells from bone marrow or epithelial stem cells present in bone marrow or circulation and (c fat-derived mesenchymal cells. Airway epithelial cells can be co-cultured in a system that includes a basal lamina equivalent, extracellular factors from mesenchymal fibroblasts, and in an air-liquid interface system. Recently, spheroid-based culture systems have been developed. Several clinical applications have been suggested: cystic fibrosis, acute respiratory distress syndrome, chronic obstructive lung disease, pulmonary fibrosis, pulmonary edema, and pulmonary hypertension. Clinical applications so far are few, but include subglottic stenosis, tracheomalacia, bronchiomalacia, and emphysema.

  18. Cartilage repair: surgical techniques and tissue engineering using polysaccharide- and collagen-based biomaterials.

    Science.gov (United States)

    Galois, L; Freyria, A M; Grossin, L; Hubert, P; Mainard, D; Herbage, D; Stoltz, J F; Netter, P; Dellacherie, E; Payan, E

    2004-01-01

    Lesions of articular cartilage have a large variety of causes among which traumatic damage, osteoarthritis and osteochondritis dissecans are the most frequent. Replacement of articular defects in joints has assumed greater importance in recent years. This interest results in large part because cartilage defects cannot adequately heal themselves. Many techniques have been suggested over the last 30 years, but none allows the regeneration of the damaged cartilage, i.e. its replacement by a strictly identical tissue. In the first generation of techniques, relief of pain was the main concern, which could be provided by techniques in which cartilage was replaced by fibrocartilage. Disappointing results led investigators to focus on more appropriate bioregenerative approaches using transplantation of autologous cells into the lesion. Unfortunately, none of these approaches has provided a perfect final solution to the problem. The latest generation of techniques, currently in the developmental or preclinical stages, involve biomaterials for the repair of chondral or osteochondral lesions. Many of these scaffolds are designed to be seeded with chondrocytes or progenitor cells. Among natural and synthetic polymers, collagen- and polysaccharide-based biomaterials have been extensively used. For both these supports, studies have shown that chondrocytes maintain their phenotype when cultured in three dimensions. In both types of culture, a glycosaminoglycan-rich deposit is formed on the surface and in the inner region of the cultured cartilage, and type II collagen synthesis is also observed. Dynamic conditions can also improve the composition of such three-dimensional constructs. Many improvements are still required, however, in a number of key aspects that so far have received only scant attention. These aspects include: adhesion/integration of the graft with the adjacent native cartilage, cell-seeding with genetically-modified cell populations, biomaterials that can be

  19. Motorcycle Repair.

    Science.gov (United States)

    Hein, Jim; Bundy, Mike

    This motorcycle repair curriculum guide contains the following ten areas of study: brake systems, clutches, constant mesh transmissions, final drives, suspension, mechanical starting mechanisms, electrical systems, fuel systems, lubrication systems, and overhead camshafts. Each area consists of one or more units of instruction. Each instructional…

  20. Effect of Kettlebell Lifting on Physical Condition of Future Mechanical Engineers

    Directory of Open Access Journals (Sweden)

    А. П. Конох

    2016-08-01

    Full Text Available The objective of the paper is to study the effect of exercises with kettlebell lifting elements on the physical condition of future mechanical engineers. Materials and methods. To address the tasks set, the study used the following research methods: theoretical analysis and collation of literary sources; implementation of a pilot program of physical education through kettlebell lifting in higher agricultural educational institutions; methods of mathematical statistics. Research results. The paper focuses on the relevant issue of theoretical and methodological support of the process of improving students' physical condition. The study has determined the effect of kettlebell lifting on the physical condition of the future mechanical engineers involved in maintenance and repair of agricultural equipment and machinery. Kettlebell lifting proves to provide good physical training, has a positive effect on the human body, and strengthens health in general. The research conducted gave grounds to determine that the level of the physical condition of the test group students is satisfactory on all indicators. This meets the requirements set before the future specialists. Conclusions. The study of the effectiveness of kettlebell lifting influence on the physical condition of the test group students yielded positive results. As a result, the training improves the performance of the students’ respiratory and cardiovascular systems, decreases their heart rate and blood pressure, enhances economization of the body systems performance at rest and at load, boosts the reserve capacity of these systems, reduces the recovery period after load, and improves the metabolic processes, which contributes to enhancing the organism tolerance to the unfavorable factors of the profession-related activity.

  1. In vitro construction of tissue engineered skin for wound repair after escharectomy of third degree scald: An experimental study

    Directory of Open Access Journals (Sweden)

    Zhong-feng MA

    2016-01-01

    Full Text Available Objective  To observe the practicability and effect of tissue engineered skin for repairing the wound after escharectomy of third degree scald (TDSE in rat model. Methods  Epithelial cells and fibroblasts from newborn SD rats were isolated by enzyme digestion method and cultured in vitro, and porcine acellular dermal matrix (PADM without cytotoxicity was prepared by hyperosmotic saline/sodium hydroxide method. The fibroblasts were mixed with bovine type Ⅰ collagen and inoculated on the surface of PADM. Third passage of cultured epidermal cells from newborn SD rats were inoculated on the collagen surface of the dermal matrix to obtain tissue engineered skin, and it was used to prepare epidermal cell sheet. Forty-eight SD rats with TDSE wound were randomly divided into two groups, then tissue engineered skin (experiment group, and epidermal cell sheet (control group graftings were performed to cover the wounds respectively. Finally, gross observation and histological changes were observed in grafted area. The wound healing rate and wound contraction rate were compared between the two groups. Microvessel count (MVC was performed with antiCD34 monoclonal antibody immunohistochemical staining technique, and vascular endothelial cells were labeled. Basal membrane of the skin was identified by immunohistochemical anti-Laminin staining technique. Results  There was no obvious sign of acute rejection of the graft in both groups. The graft survival rate was 75.05%±3.69%, 83.12%±3.13% and 92.03%±3.87% at the 2th, 4th and 6th week respectively in the experimental group. The graft survival rate was 77.63%±3.23%, 83.17%±3.92% and 91.09%±3.35% at the 2th, 4th and 6th week in the control group. There was no significant difference between the two groups (P>0.05, but the contraction rate of the grafts was 9.13%±2.27%, 18.52%±3.40%, 23.92%±3.01% at the 2th, 4th, 6th week, respectively, in the experimental group, and 14.21%±3.05%, 29.12%±3

  2. Mechanism of protein kinetic stabilization by engineered disulfide crosslinks.

    Directory of Open Access Journals (Sweden)

    Inmaculada Sanchez-Romero

    Full Text Available The impact of disulfide bonds on protein stability goes beyond simple equilibrium thermodynamics effects associated with the conformational entropy of the unfolded state. Indeed, disulfide crosslinks may play a role in the prevention of dysfunctional association and strongly affect the rates of irreversible enzyme inactivation, highly relevant in biotechnological applications. While these kinetic-stability effects remain poorly understood, by analogy with proposed mechanisms for processes of protein aggregation and fibrillogenesis, we propose that they may be determined by the properties of sparsely-populated, partially-unfolded intermediates. Here we report the successful design, on the basis of high temperature molecular-dynamics simulations, of six thermodynamically and kinetically stabilized variants of phytase from Citrobacter braakii (a biotechnologically important enzyme with one, two or three engineered disulfides. Activity measurements and 3D crystal structure determination demonstrate that the engineered crosslinks do not cause dramatic alterations in the native structure. The inactivation kinetics for all the variants displays a strongly non-Arrhenius temperature dependence, with the time-scale for the irreversible denaturation process reaching a minimum at a given temperature within the range of the denaturation transition. We show this striking feature to be a signature of a key role played by a partially unfolded, intermediate state/ensemble. Energetic and mutational analyses confirm that the intermediate is highly unfolded (akin to a proposed critical intermediate in the misfolding of the prion protein, a result that explains the observed kinetic stabilization. Our results provide a rationale for the kinetic-stability consequences of disulfide-crosslink engineering and an experimental methodology to arrive at energetic/structural descriptions of the sparsely populated and elusive intermediates that play key roles in irreversible

  3. Incorporating a Product Archaeology Paradigm across the Mechanical Engineering Curriculum

    Science.gov (United States)

    Moore-Russo, Deborah; Cormier, Phillip; Lewis, Kemper; Devendorf, Erich

    2013-01-01

    Historically, the teaching of design theory in an engineering curriculum has been relegated to a senior capstone design experience. Presently, however, engineering design concepts and courses can be found through the entirety of most engineering programs. Educators have recognized that engineering design provides a foundational platform that can…

  4. Applications of the discrete element method in mechanical engineering

    Energy Technology Data Exchange (ETDEWEB)

    Fleissner, Florian, E-mail: fleissner@itm.uni-stuttgart.de; Gaugele, Timo, E-mail: gaugele@itm.uni-stuttgart.de; Eberhard, Peter [University of Stuttgart, Institute of Engineering and Computational Mechanics (Germany)], E-mail: eberhard@itm.uni-stuttgart.de

    2007-08-15

    Compared to other fields of engineering, in mechanical engineering, the Discrete Element Method (DEM) is not yet a well known method. Nevertheless, there is a variety of simulation problems where the method has obvious advantages due to its meshless nature. For problems where several free bodies can collide and break after having been largely deformed, the DEM is the method of choice. Neighborhood search and collision detection between bodies as well as the separation of large solids into smaller particles are naturally incorporated in the method. The main DEM algorithm consists of a relatively simple loop that basically contains the three substeps contact detection, force computation and integration. However, there exists a large variety of different algorithms to choose the substeps to compose the optimal method for a given problem. In this contribution, we describe the dynamics of particle systems together with appropriate numerical integration schemes and give an overview over different types of particle interactions that can be composed to adapt the method to fit to a given simulation problem. Surface triangulations are used to model complicated, non-convex bodies in contact with particle systems. The capabilities of the method are finally demonstrated by means of application examples.

  5. Tunable engineered skin mechanics via coaxial electrospun fiber core diameter.

    Science.gov (United States)

    Blackstone, Britani Nicole; Drexler, Jason William; Powell, Heather Megan

    2014-10-01

    Autologous engineered skin (ES) offers promise as a treatment for massive full thickness burns. Unfortunately, ES is orders of magnitude weaker than normal human skin causing it to be difficult to apply surgically and subject to damage by mechanical shear in the early phases of engraftment. In addition, no manufacturing strategy has been developed to tune ES biomechanics to approximate the native biomechanics at different anatomic locations. To enhance and tune ES biomechanics, a coaxial (CoA) electrospun scaffold platform was developed from polycaprolactone (PCL, core) and gelatin (shell). The ability of the coaxial fiber core diameter to control both scaffold and tissue mechanics was investigated along with the ability of the gelatin shell to facilitate cell adhesion and skin development compared to pure gelatin, pure PCL, and a gelatin-PCL blended fiber scaffold. CoA ES exhibited increased cellular adhesion and metabolism versus PCL alone or gelatin-PCL blend and promoted the development of well stratified skin with a dense dermal layer and a differentiated epidermal layer. Biomechanics of the scaffold and ES scaled linearly with core diameter suggesting that this scaffold platform could be utilized to tailor ES mechanics for their intended grafting site and reduce graft damage in vitro and in vivo.

  6. Approach to the classical radiation biology. Ionizing radiation effects and repair mechanism of DNA double strand breaks

    Energy Technology Data Exchange (ETDEWEB)

    Utsumi, Hiroshi [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst

    2000-09-01

    Split-dose recovery has been observed under a variety of experimental conditions in many cell systems and believed to be the recovery of sublethal damage (SLD). It is considered to be one of the most widespread and important cellular responses in clinical radiotherapy. To study the molecular mechanism of this recovery, we analyzed the knockout mutants KU70{sup -/-}, RAD54{sup -/-}, and KU70{sup -/-}/ RAD54{sup -/-} of the chicken B-cell line, DT40. Rad54 participates in the homologous recombinational (HR) repair of DNA double-strand breaks (DSB), while Ku proteins are involved in non-homologous end-joining (NHEJ). Split-dose recovery was observed in the parent DT40 and KU70{sup -/-} cells. Moreover the split-dose survival enhancement had all of the characteristics of SLD recovery that had been demonstrated earlier: e.g., the reappearance of the shoulder of the survival curve with dose fractionation; repair at 25degC; and inhibition by the antibiotic actinomycin D. These results strongly suggest that SLD recovery is due to DSB repair via or mediated by HR, and that these breaks constitute SLD. The tonicity-sensitive potentially lethal damage (PLD) recovery was also found only in DT40 and KU70 {sup -/-} cells. Delayed-plating PLD recovery may be controlled by NHEJ repair that works through the cell cycle. These results lead to the conclusion that the repair of DSBs could explain the classical operational recovery phenomena. We have also investigated RBE/LET using those mutants. (author)

  7. Is the Dresden technique a mechanical design of choice suitable for the repair of middle third Achilles tendon ruptures? A biomechanical study.

    Science.gov (United States)

    de la Fuente, C; Carreño-Zillmann, G; Marambio, H; Henríquez, H

    2016-01-01

    To compare the mechanical failure of the Dresden technique for Achilles tendon repair with the double modified Kessler technique controlled repair technique. The maximum resistance of the two repair techniques are also compared. A total of 30 Achilles tendon ruptures in bovine specimens were repaired with an Ethibond(®) suture to 4.5cm from the calcaneal insertion. Each rupture was randomly distributed into one of two surgical groups. After repair, each specimen was subjected to a maximum traction test. The mechanical failure (tendon, suture, or knot) rates (proportions) were compared using the exact Fisher test (α=.05), and the maximum resistances using the Student t test (α=.05). There was a difference in the proportions of mechanical failures, with the most frequent being a tendon tear in the Dresden technique, and a rupture of the suture in the Kessler technique. The repair using the Dresden technique performed in the open mode, compared to the Kessler technique, has a more suitable mechanical design for the repair of middle third Achilles tendon ruptures on developing a higher tensile resistance in 58.7%. However, its most common mechanical failure was a tendon tear, which due to inappropriate loads could lead to lengthening of the Achilles tendon. Copyright © 2016 SECOT. Publicado por Elsevier España, S.L.U. All rights reserved.

  8. A concise introduction to mechanics of rigid bodies multidisciplinary engineering

    CERN Document Server

    Huang, L

    2017-01-01

    This updated second edition broadens the explanation of rotational kinematics and dynamics — the most important aspect of rigid body motion in three-dimensional space and a topic of much greater complexity than linear motion. It expands treatment of vector and matrix, and includes quaternion operations to describe and analyze rigid body motion which are found in robot control, trajectory planning, 3D vision system calibration, and hand-eye coordination of robots in assembly work, etc. It features updated treatments of concepts in all chapters and case studies. The textbook retains its comprehensiveness in coverage and compactness in size, which make it easily accessible to the readers from multidisciplinary areas who want to grasp the key concepts of rigid body mechanics which are usually scattered in multiple volumes of traditional textbooks. Theoretical concepts are explained through examples taken from across engineering disciplines and links to applications and more advanced courses (e.g. industrial rob...

  9. Quantitative Ultrasonic Evaluation of Mechanical Properties of Engineering Materials

    Science.gov (United States)

    Vary, A.

    1978-01-01

    Progress in the application of ultrasonic techniques to nondestructive measurement of mechanical strength of engineering materials is reviewed. A dormant concept in nondestructive evaluation (NDE) is invoked. The availability of ultrasonic methods that can be applied to actual parts to assess their potential susceptibility to failure under design conditions is discussed. It was shown that ultrasonic methods yield measurements of elastic moduli, microstructure, hardness, fracture toughness, tensile strength, yield strength, and shear strength for a wide range of materials (including many types of metals, ceramics, and fiber composites). It was also indicated that although most of these methods were shown feasible in laboratory studies, more work is needed before they can be used on actual parts in processing, assembly, inspection, and maintenance lines.

  10. Effect of Chitosan on Tissue Repair in Bone Tissue Engineering%壳聚糖对骨组织工程中组织修复的影响

    Institute of Scientific and Technical Information of China (English)

    焦延鹏; 李立华; 罗丙红; 周长忍

    2012-01-01

    Materials implanted in the body would inevitably lead to host response, promoting or inhibiting tissue heal- ing. The degradation products of biodegradable materials in the body will change with time, resulting in different host re- sponses and further affecting tissue healing. Therefore, the mechanism of promoting or inhibiting tissue healing becomes the theoretical basis for the design and preparation of novel biomedical polymer materials. Chitosan is one of the ideal med- ical polymer materials, but we still do not know the effect mechanism of chitosan degradation process on tissue repair in vi- vo. So it will not be able to design chitosan-based materials with excellent performance. This review does not lay out the progress of the chitosan-based biomaterials applied in bone tissue engineering, but focuses on the complexity of chitosan applications for bone tissue engineering, furthermore investigates the problems needed to be solved for chitosan used in bone tissue engineering.%材料植入体内必然引起宿主体的应答,促进或抑制组织愈合。由于降解材料在体内的降解产物会随时间而变,产生的宿主体应答就会不同,进而会影响组织的愈合。而促进或抑制组织愈合的机制就成为新型医用高分子材料设计和制备的理论基础。壳聚糖是理想的骨组织修复材料之一,但至今还不清楚壳聚糖体内不同降解过程对组织修复的影响机制,也就无法设计出性能优良的壳聚糖基新材料。文章没有罗列壳聚糖基生物材料在骨组织工程中应用所取得的进展,而是重点阐述了壳聚糖在骨组织工程中应用的复杂性和对组织修复的影响,探讨了壳聚糖进一步用于骨组织工程所需要解决的问题。

  11. Delayed onset of tricuspid valve flow in repaired tetralogy of Fallot: an additional mechanism of diastolic dysfunction and interventricular dyssynchrony

    Directory of Open Access Journals (Sweden)

    Benson Lee N

    2011-08-01

    Full Text Available Abstract Background Diastolic dysfunction of the right ventricle (RV is common after repair of tetralogy of Fallot. While restrictive physiology in late diastole has been well known, dysfunction in early diastole has not been described. The present study sought to assess the prevalence and mechanism of early diastolic dysfunction of the RV defined as delayed onset of the tricuspid valve (TV flow after TOF repair. Methods The study population consisted of 31 children with repaired TOF (mean age ± SD, 12.3 ± 4.1 years who underwent postoperative cardiovascular magnetic resonance (CMR. The CMR protocol included simultaneous phase-contrast velocity mapping of the atrioventricular valves, which enabled direct comparison of the timing and patterns of tricuspid (TV and mitral (MV valve flow. The TV flow was defined to have delayed onset when its onset was > 20 ms later than the onset of the MV flow. The TV and MV flow from 14 normal children was used for comparison. The CMR results were correlated with the findings on echocardiography and electrocardiography. Result Delayed onset of the TV flow was observed in 16/31 patients and in none of the controls. The mean delay time was 64.81 ± 27.07 ms (8.7 ± 3.2% of R-R interval. The delay time correlated with the differences in duration of the TV and MV flow (55.94 ± 32.88 ms (r = 0.90, p Conclusions Early diastolic dysfunction with delayed onset of TV flow is common after TOF repair, and is associated with reduced RV ejection fraction. It is a further manifestation of interventricular dyssynchrony and represent an additional mechanism of ventricular diastolic dysfunction.

  12. Outer organic layer and internal repair mechanism protects pteropod Limacina helicina from ocean acidification

    Science.gov (United States)

    Peck, Victoria L.; Tarling, Geraint A.; Manno, Clara; Harper, Elizabeth M.; Tynan, Eithne

    2016-05-01

    Scarred shells of polar pteropod Limacina helicina collected from the Greenland Sea in June 2012 reveal a history of damage, most likely failed predation, in earlier life stages. Evidence of shell fracture and subsequent re-growth is commonly observed in specimens recovered from the sub-Arctic and further afield. However, at one site within sea-ice on the Greenland shelf, shells that had been subject to mechanical damage were also found to exhibit considerable dissolution. It was evident that shell dissolution was localised to areas where the organic, periostracal sheet that covers the outer shell had been damaged at some earlier stage during the animal's life. Where the periostracum remained intact, the shell appeared pristine with no sign of dissolution. Specimens which appeared to be pristine following collection were incubated for four days. Scarring of shells that received periostracal damage during collection only became evident in specimens that were incubated in waters undersaturated with respect to aragonite, ΩAr≤1. While the waters from which the damaged specimens were collected at the Greenland Sea sea-ice margin were not ΩAr≤1, the water column did exhibit the lowest ΩAr values observed in the Greenland and Barents Seas, and was likely to have approached ΩAr≤1 during the winter months. We demonstrate that L. helicina shells are only susceptible to dissolution where both the periostracum has been breached and the aragonite beneath the breach is exposed to waters of ΩAr≤1. Exposure of multiple layers of aragonite in areas of deep dissolution indicate that, as with many molluscs, L. helicina is able to patch up dissolution damage to the shell by secreting additional aragonite internally and maintain their shell. We conclude that, unless breached, the periostracum provides an effective shield for pteropod shells against dissolution in waters ΩAr≤1, and when dissolution does occur the animal has an effective means of self-repair. We suggest

  13. Pension helpdesk calls : A repair mechanism in the client communication of financial institutions

    NARCIS (Netherlands)

    Nell, Louise; Lentz, Leo; Pander Maat, Henk; Koole, Tom

    2015-01-01

    This paper analyzes the role of helpdesk calls in the client communication package of pension funds.Our audio-corpus of 77 helpdesk calls contained 104 client questions. These show that clients seem tocall the helpdesk in order to repair a comprehension problem, to find specific information they mis

  14. Mechanisms and consequences of injury and repair in older organ transplants

    NARCIS (Netherlands)

    B.R. Slegtenhorst (Bendix); F.J.M.F. Dor (Frank); A. Elkhal (Abdala); H. Rodriguez (Hector); X. Yang (Xiaoyong); K. Edtinger (Karoline); R. Quante (Rainer); A.S. Chong (Anita); S.G. Tullius (Stefan)

    2014-01-01

    textabstractDonor organ scarcity remains a significant clinical challenge in transplantation. Older organs, increasingly utilized to meet the growing demand for donor organs, have been linked to inferior transplant outcomes. Susceptibility to organ injury, reduced repair capacity, and increased immu

  15. Dss1 interaction with Brh2 as a regulatory mechanism for recombinational repair

    DEFF Research Database (Denmark)

    Zhou, Qingwen; Kojic, Milorad; Cao, Zhimin;

    2007-01-01

    Brh2, the BRCA2 ortholog in Ustilago maydis, enables recombinational repair of DNA by controlling Rad51 and is in turn regulated by Dss1. Interplay with Rad51 is conducted via the BRC element located in the N-terminal region of the protein and through an unrelated domain, CRE, at the C terminus...

  16. Poly(lactic-co-glycolic acid) conduit for repair of injured sciatic nerve A mechanical analysis*

    Institute of Scientific and Technical Information of China (English)

    Tao Yu; Changfu Zhao; Peng Li; Guangyao Liu; Min Luo

    2013-01-01

    Tensile stress and tensile strain directly affect the quality of nerve regeneration after bridging nerve defects by poly(lactic-co-glycolic acid) conduit transplantation and autogenous nerve grafting for sciatic nerve injury. This study col ected the sciatic nerve from the gluteus maximus muscle from fresh human cadaver, and established 10-mm-long sciatic nerve injury models by removing the ischium, fol owing which poly(lactic-co-glycolic acid) conduits or autogenous nerve grafts were transplanted. Scanning electron microscopy revealed that the axon and myelin sheath were torn, and the vessels of basilar membrane were obstructed in the poly(lactic-co-glycolic acid) con-duit-repaired sciatic nerve fol owing tensile testing. There were no significant differences in tensile tests with autogenous nerve graft-repaired sciatic nerve. Fol owing poly(lactic-co-glycolic acid) conduit transplantation for sciatic nerve repair, tensile test results suggest that maximum tensile load, maximum stress, elastic limit load and elastic limit stress increased compared with autogen-ous nerve grafts, but elastic limit strain and maximum strain decreased. Moreover, the tendencies of stress-strain curves of sciatic nerves were similar after transplantation of poly(lactic-co-glycolic acid) conduits or autogenous nerve grafts. Results showed that after transplantation in vitro for sciatic nerve injury, poly(lactic-co-glycolic acid) conduits exhibited good intensity, elasticity and plasticity, indicating that poly(lactic-co-glycolic acid) conduits are suitable for sciatic nerve injury repair.

  17. Mechanical restoration and failure analyses of a hydrogel and scaffold composite strategy for annulus fibrosus repair

    NARCIS (Netherlands)

    Long, Rose G.; Buerki, Alexander; Zysset, Philippe; Eglin, David; Grijpma, Dirk W.; Blanquer, Sebastien B. G.; Hecht, Andrew C.; Iatridis, James C.

    2016-01-01

    Unrepaired defects in the annulus fibrosus of intervertebral disks are associated with degeneration and persistent back pain. A clinical need exists for a disk repair strategy that can seal annular defects, be easily delivered during surgical procedures, and restore biomechanics with low risk of her

  18. Poly(lactic-co-glycolic acid) conduit for repair of injured sciatic nerve: A mechanical analysis.

    Science.gov (United States)

    Yu, Tao; Zhao, Changfu; Li, Peng; Liu, Guangyao; Luo, Min

    2013-07-25

    Tensile stress and tensile strain directly affect the quality of nerve regeneration after bridging nerve defects by poly(lactic-co-glycolic acid) conduit transplantation and autogenous nerve grafting for sciatic nerve injury. This study collected the sciatic nerve from the gluteus maximus muscle from fresh human cadaver, and established 10-mm-long sciatic nerve injury models by removing the ischium, following which poly(lactic-co-glycolic acid) conduits or autogenous nerve grafts were transplanted. Scanning electron microscopy revealed that the axon and myelin sheath were torn, and the vessels of basilar membrane were obstructed in the poly(lactic-co-glycolic acid) conduit-repaired sciatic nerve following tensile testing. There were no significant differences in tensile tests with autogenous nerve graft-repaired sciatic nerve. Following poly(lactic-co-glycolic acid) conduit transplantation for sciatic nerve repair, tensile test results suggest that maximum tensile load, maximum stress, elastic limit load and elastic limit stress increased compared with autogenous nerve grafts, but elastic limit strain and maximum strain decreased. Moreover, the tendencies of stress-strain curves of sciatic nerves were similar after transplantation of poly(lactic-co-glycolic acid) conduits or autogenous nerve grafts. Results showed that after transplantation in vitro for sciatic nerve injury, poly(lactic-co-glycolic acid) conduits exhibited good intensity, elasticity and plasticity, indicating that poly(lactic-co-glycolic acid) conduits are suitable for sciatic nerve injury repair.

  19. Dynamics and control of mechanical systems in offshore engineering

    CERN Document Server

    He, Wei; How, Bernard Voon Ee; Choo, Yoo Sang

    2014-01-01

    Dynamics and Control of Mechanical Systems in Offshore Engineering is a comprehensive treatment of marine mechanical systems (MMS) involved in processes of great importance such as oil drilling and mineral recovery. Ranging from nonlinear dynamic modeling and stability analysis of flexible riser systems, through advanced control design for an installation system with a single rigid payload attached by thrusters, to robust adaptive control for mooring systems, it is an authoritative reference on the dynamics and control of MMS. Readers will gain not only a complete picture of MMS at the system level, but also a better understanding of the technical considerations involved and solutions to problems that commonly arise from dealing with them. The text provides:                                                                                                                                 ...

  20. A Novel bioreactor with mechanical stimulation for skeletal tissue engineering

    Directory of Open Access Journals (Sweden)

    M. Petrović

    2009-01-01

    Full Text Available The provision of mechanical stimulation is believed to be necessary for the functional assembly of skeletal tissues, which are normally exposed to a variety of biomechanical signals in vivo. In this paper, we present a development and validation of a novel bioreactor aimed for skeletal tissue engineering that provides dynamic compression and perfusion of cultivated tissues. Dynamic compression can be applied at frequencies up to 67.5 Hz and displacements down to 5 m thus suitable for the simulation of physiological conditions in a native cartilage tissue (0.1-1 Hz, 5-10 % strain. The bioreactor also includes a load sensor that was calibrated so to measure average loads imposed on tissue samples. Regimes of the mechanical stimulation and acquisition of load sensor outputs are directed by an automatic control system using applications developed within the LabView platform. In addition, perfusion of tissue samples at physiological velocities (10–100 m/s provides efficient mass transfer, as well as the possibilities to expose the cells to hydrodynamic shear and simulate the conditions in a native bone tissue. Thus, the novel bioreactor is suited for studies of the effects of different biomechanical signals on in vitro regeneration of skeletal tissues, as well as for the studies of newly formulated biomaterials and cell biomaterial interactions under in vivo-like settings.

  1. Transcription-coupled nucleotide excision repair in mammalian cells: molecular mechanisms and biological effects

    Institute of Scientific and Technical Information of China (English)

    Mafia Fousteri; Leon HF Mullenders

    2008-01-01

    The encounter of elongating RNA polymerase Ⅱ (RNAPIIo) with DNA lesions has severe consequences for the cell as this event provides a strong signal for P53-dependent apoptosis and cell cycle arrest. To counteract prolonged blockage of transcription, the cell removes the RNAPllo-hlocking DNA lesions by transcription-coupled repair (TC-NER), a specialized subpathway of nucleotide excision repair (NER). Exposure of mice to UVB light or chemicals has elucidated that TC-NER is a critical survival pathway protecting against acute toxic and long-term effects (cancer) of genotoxic exposure. Deficiency in TC-NER is associated with mutations in the CSA and CSB genes giving rise to the rare hu-man disorder Cockayne syndrome (CS). Recent data suggest that CSA and CSB play differential roles in mammalian TC-NER: CSB as a repair coupling factor to attract NER proteins, chromatin remodellers and the CSA- E3-ubiquitin iigase complex to the stalled RNAPI io. CSA is dispensable for attraction of NER proteins, yet in cooperation with CSB is required to recruit XAB2, the nucleosomal binding protein HMGNl and TFIIS. The emerging picture of TC-NER is complex: repair of transcription-blocking lesions occurs without displacement of the DNA damage-stalled RNAPIIo, and requires at least two essential assembly factors (CSA and CSB), the core NER factors (except for XPC-RAD23B), and TC-NER specific factors. These and yet unidentified proteins will accomplish not only efficient repair of transcrip-tion-blocking lesions, but are also likely to contribute to DNA damage signalling events.

  2. Analytical expression for an optimised link bar mechanism for a beta-type Stirling engine

    DEFF Research Database (Denmark)

    Carlsen, Henrik; Bovin, Jonas Kabell

    2007-01-01

    The design of a mechanism for kinematic beta-type Stirling engines, where the displacer piston and the working piston share the same cylinder, is complicated. A well-known solution is the rhombic drive, but this solution depends on oil lubrication because of the gear wheels connecting the two...... mechanism is a further development of the mechanism in a previous 9 kW engine. The crank mechanism for the beta-type Stirling engine is based on two four-link straight line mechanisms pointing up and down, respectively. The mechanism pointing upwards is connected to the working piston, while the mechanism...... counter rotating crank shafts. In a hermetically sealed Stirling engine it is an advantage to avoid oil in the crank case, making the application of the rhombic drive difficult. In this paper, another crank mechanism is presented, which has been developed for a 9 kW single cylinder engine. The new crank...

  3. Mechanical behaviour of a fibrous scaffold for ligament tissue engineering: finite elements analysis vs. X-ray tomography imaging.

    Science.gov (United States)

    Laurent, Cédric P; Latil, Pierre; Durville, Damien; Rahouadj, Rachid; Geindreau, Christian; Orgéas, Laurent; Ganghoffer, Jean-François

    2014-12-01

    The use of biodegradable scaffolds seeded with cells in order to regenerate functional tissue-engineered substitutes offers interesting alternative to common medical approaches for ligament repair. Particularly, finite element (FE) method enables the ability to predict and optimise both the macroscopic behaviour of these scaffolds and the local mechanic signals that control the cell activity. In this study, we investigate the ability of a dedicated FE code to predict the geometrical evolution of a new braided and biodegradable polymer scaffold for ligament tissue engineering by comparing scaffold geometries issued from FE simulations and from X-ray tomographic imaging during a tensile test. Moreover, we compare two types of FE simulations the initial geometries of which are issued either from X-ray imaging or from a computed idealised configuration. We report that the dedicated FE simulations from an idealised reference configuration can be reasonably used in the future to predict the global and local mechanical behaviour of the braided scaffold. A valuable and original dialog between the fields of experimental and numerical characterisation of such fibrous media is thus achieved. In the future, this approach should enable to improve accurate characterisation of local and global behaviour of tissue-engineering scaffolds.

  4. Draft fracture mechanics code case for American Society of Mechanical Engineers NUPACK rules

    Energy Technology Data Exchange (ETDEWEB)

    McConnell, P.; Sorenson, K. [Sandia National Labs., Albuquerque (United States); Nickell, R. [Applied Science and Technology, Poway (United States); Saegusa, T. [Central Research Inst. for Electric Power Industry, Abiko (Japan)

    2004-07-01

    The containment boundaries of most spent-fuel casks certified for use in the United States by the Nuclear Regulatory Commission are constructed with stainless steel, a material that is ductile in an engineering sense at all temperatures and for which, therefore, fracture mechanics principles are not relevant for the containment application. Ferritic materials may fail in a nonductile manner at sufficiently low temperatures, so fracture mechanics principles may be applied to preclude nonductile fracture. Because of the need to transport and store spent nuclear fuel safely in all types of climatic conditions, these vessels have regulatory lowest service temperatures that range down to -40 C (-40 F) for transport application. Such low service temperatures represent a severe challenge in terms of fracture toughness to many ferritic materials. Linear-elastic and elastic-plastic fracture mechanics principles provide a methodology for evaluating ferritic materials under such conditions.

  5. Effect of different mechanical and chemical surface treatments on the repaired bond strength of an indirect composite resin.

    Science.gov (United States)

    Kimyai, Soodabeh; Oskoee, Siavash Savadi; Mohammadi, Narmin; Rikhtegaran, Sahand; Bahari, Mahmoud; Oskoee, Parnian Alizadeh; Vahedpour, Hafez

    2015-02-01

    This study compared the effects of two mechanical surface preparation techniques, air abrasion and Nd:YAG laser, with the use of two adhesive systems, self-etch and etch and rinse, on the repair bond strengths of an indirect composite resin. One hundred fifty cylindrical samples of an indirect composite resin were prepared and randomly divided into six groups (n = 25). In groups 1-3, the composite resin surfaces were respectively prepared as follows: no roughening, roughening by air abrasion, and roughening by Nd:YAG laser, followed by application of an etch-and-rinse adhesive. In groups 4-6, the preparation techniques were respectively the same as those in groups 1-3, followed by application of a self-etch adhesive. Subsequently, a direct composite resin was added and repair bond strengths were measured. Data were analyzed with two-way ANOVA and post hoc Tukey's test. Mean bond strength value was significant based on the preparation technique (P composite resin with air abrasion and Nd:YAG laser resulted in a significant increase in the repair bond strength, with air abrasion being more effective. There were no significant differences in bond strength between the two adhesives.

  6. A Systems Engineering Approach to Electro-Mechanical Actuator Diagnostic and Prognostic Development

    Data.gov (United States)

    National Aeronautics and Space Administration — The authors have formulated a Comprehensive Systems Engineering approach to Electro-Mechanical Actuator (EMA) Prognostics and Health Management (PHM) system...

  7. Validation of the Algorithms for Base Exchangeable Repair Costs (Engine) and Base Exchangeable Modification Costs (Engine) for the Component Support Cost System (D160B).

    Science.gov (United States)

    2014-09-26

    REPORTING 010 03 NUMBER. ITEM IDENTIFICATION Oil 03 NOMENCLATURE . ITEM 012 03 PRICE. STANDARD INVENTORY 013 03 CODE, WEAPON SYSTEM SUPPORT 014 05 CODE...elements not used in calculation of standard depot repair prices (* sales prices"). ISI affirms the congruence of the definitions of repair prices as

  8. Mechanisms of DNA repair and radio-induced mutagenesis in higher eukaryotes; Mecanismes de reparation et mutagenese radio-induite chez les eucaryotes superieurs

    Energy Technology Data Exchange (ETDEWEB)

    Averbeck, D. [Centre Universitaire d' Orsay, Institut Curie, Section de Recherche, Lab. Raymond-Latarjet, UMR 2027 CNRS, 91 (France)

    2000-10-01

    Cells of higher eukaryotes possess several very efficient systems for the repair of radiation-induced lesions in DNA. Different strategies have been adopted at the cellular level to remove or even tolerate various types of lesions in order to assure survival and limit the mutagenic consequences. In mammalian cells, the main DNA repair systems comprise direct reversion of damage, excision of damage and exchange mechanisms with intact DNA. Among these, the direct ligation of single strand breaks (SSB) by a DNA ligase and the multi-enzymatic repair systems of mismatch repair, base and nucleotide excision repair as well as the repair of double strand breaks (DSB) by homologous recombination or non homologous end-joining are the most important systems. Most of these processes are error-free except the non homologous end-joining pathway used for the repair of DSB. Moreover, certain lesions can be tolerated by more or less accurately acting polymerases capable of performing trans-lesion DNA syntheses. The DNA repair systems are intimately integrated in the network of cellular regulation. Some of their components are DNA damage inducible. Radiation-induced mutagenesis is largely due to unrepaired DNA damage but also involves error-prone repair processes like the repair of DSB by non-homologous end-joining. Generally, mammalian cells are well prepared to repair radiation-induced lesions. However, some questions remain to be asked about mechanistic details and efficiencies of the systems for removing certain types of radiation-damage and about their order and timing of action. The answers to these questions would be important for radioprotection as well as radiotherapy. (author)

  9. The green microalga Tetraselmis suecica reduces oxidative stress and induces repairing mechanisms in human cells

    Science.gov (United States)

    Sansone, Clementina; Galasso, Christian; Orefice, Ida; Nuzzo, Genoveffa; Luongo, Elvira; Cutignano, Adele; Romano, Giovanna; Brunet, Christophe; Fontana, Angelo; Esposito, Francesco; Ianora, Adrianna

    2017-01-01

    Green microalgae contain many active pigments such as carotenoids having antioxidant and protective activity on human cells. Here we investigate the biological activity of an ethanol/water extract of the marine green microalga Tetraselmis suecica containing high levels of carotenoids such as the xanthophylls lutein, violaxanthin, neoxanthin, antheraxanthin and loroxanthin esters. This extract has a strong antioxidant and repairing activity in the human lung cancer cell line (A549) as shown by the increased expression of dehydrocholesterol reductase-24 (DHCR24) and prostaglandin reductase 1 (PTGR1) genes and proteins. The extract also reduces prostaglandin E2 (PGE2) levels in cells damaged by H2O2 and has tissue repairing effects on reconstructed human epidermal tissue cells (EpiDermTM) indicating a potential cosmeceutical activity of this microalgal species. PMID:28117410

  10. Arsenic Biotransformation as a Cancer Promoting Factor by Inducing DNA Damage and Disruption of Repair Mechanisms

    Directory of Open Access Journals (Sweden)

    Victor D. Martinez

    2011-01-01

    Full Text Available Chronic exposure to arsenic in drinking water poses a major global health concern. Populations exposed to high concentrations of arsenic-contaminated drinking water suffer serious health consequences, including alarming cancer incidence and death rates. Arsenic is biotransformed through sequential addition of methyl groups, acquired from s-adenosylmethionine (SAM. Metabolism of arsenic generates a variety of genotoxic and cytotoxic species, damaging DNA directly and indirectly, through the generation of reactive oxidative species and induction of DNA adducts, strand breaks and cross links, and inhibition of the DNA repair process itself. Since SAM is the methyl group donor used by DNA methyltransferases to maintain normal epigenetic patterns in all human cells, arsenic is also postulated to affect maintenance of normal DNA methylation patterns, chromatin structure, and genomic stability. The biological processes underlying the cancer promoting factors of arsenic metabolism, related to DNA damage and repair, will be discussed here.

  11. A fracture mechanics analysis of bonded repaired skin/stiffener structures with inclined central crack

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Ki Hyun; Yang, Won Ho; Kim, Cheol; Heo, Sung Pil [Sungkyunkwan Univ., Seoul (Korea, Republic of); Ko, Myung Hoon [Daelim College, Anyang (Korea, Republic of)

    2001-07-01

    Composite patch repair of cracked aircraft structures has been accepted as one of improving fatigue life and attaining better structural integrity. Analysis for the stress intensity factor at the skin/stiffener structure with inclined central crack repaired by composite stiffened panels are developed. A numerical investigation was conducted to characterize the fracture behavior and crack growth behavior. In order to investigate the crack growth direction, Maximum Tangential Stress(MTS) criteria is used. The main objective of this research is the validation of the inclined crack patching design. In this paper, the reduction of stresses intensity factors at the crack-tip and prediction of crack growth direction are determined to evaluate the effects of various non-dimensional design parameter including; composite patch thickness and stiffener distance. The research on cracked structure subjected to mixed mode loading is accomplished and it is evident that more work using different approaches is necessary.

  12. The green microalga Tetraselmis suecica reduces oxidative stress and induces repairing mechanisms in human cells.

    Science.gov (United States)

    Sansone, Clementina; Galasso, Christian; Orefice, Ida; Nuzzo, Genoveffa; Luongo, Elvira; Cutignano, Adele; Romano, Giovanna; Brunet, Christophe; Fontana, Angelo; Esposito, Francesco; Ianora, Adrianna

    2017-01-24

    Green microalgae contain many active pigments such as carotenoids having antioxidant and protective activity on human cells. Here we investigate the biological activity of an ethanol/water extract of the marine green microalga Tetraselmis suecica containing high levels of carotenoids such as the xanthophylls lutein, violaxanthin, neoxanthin, antheraxanthin and loroxanthin esters. This extract has a strong antioxidant and repairing activity in the human lung cancer cell line (A549) as shown by the increased expression of dehydrocholesterol reductase-24 (DHCR24) and prostaglandin reductase 1 (PTGR1) genes and proteins. The extract also reduces prostaglandin E2 (PGE2) levels in cells damaged by H2O2 and has tissue repairing effects on reconstructed human epidermal tissue cells (EpiDerm(TM)) indicating a potential cosmeceutical activity of this microalgal species.

  13. Regulation of DNA repair mechanism in human glioma xenograft cells both in vitro and in vivo in nude mice.

    Directory of Open Access Journals (Sweden)

    Shivani Ponnala

    Full Text Available BACKGROUND: Glioblastoma Multiforme (GBM is the most lethal form of brain tumor. Efficient DNA repair and anti-apoptotic mechanisms are making glioma treatment difficult. Proteases such as MMP9, cathepsin B and urokinase plasminogen activator receptor (uPAR are over expressed in gliomas and contribute to enhanced cancer cell proliferation. Non-homologous end joining (NHEJ repair mechanism plays a major role in double strand break (DSB repair in mammalian cells. METHODOLOGY/PRINCIPAL FINDINGS: Here we show that silencing MMP9 in combination with uPAR/cathepsin B effects NHEJ repair machinery. Expression of DNA PKcs and Ku70/80 at both mRNA and protein levels in MMP9-uPAR (pMU and MMP9-cathepsin B (pMC shRNA-treated glioma xenograft cells were reduced. FACS analysis showed an increase in apoptotic peak and proliferation assays revealed a significant reduction in the cell population in pMU- and pMC-treated cells compared to untreated cells. We hypothesized that reduced NHEJ repair led to DSBs accumulation in pMU- and pMC-treated cells, thereby initiating cell death. This hypothesis was confirmed by reduced Ku70/Ku80 protein binding to DSB, increased comet tail length and elevated γH2AX expression in treated cells compared to control. Immunoprecipitation analysis showed that EGFR-mediated lowered DNA PK activity in treated cells compared to controls. Treatment with pMU and pMC shRNA reduced the expression of DNA PKcs and ATM, and elevated γH2AX levels in xenograft implanted nude mice. Glioma cells exposed to hypoxia and irradiation showed DSB accumulation and apoptosis after pMU and pMC treatments compared to respective controls. CONCLUSION/SIGNIFICANCE: Our results suggest that pMU and pMC shRNA reduce glioma proliferation by DSB accumulation and increase apoptosis under normoxia, hypoxia and in combination with irradiation. Considering the radio- and chemo-resistant cancers favored by hypoxia, our study provides important therapeutic potential

  14. Graduate Education Program of Design and Integration Capability at Department of Mechanical Engineering, Graduate School of Engineering, Osaka University

    Science.gov (United States)

    Fujita, Kikuo

    Department of Mechanical Engineering, Graduate School of Engineering, Osaka University is now developing “Graduate Education Program of Design and Integration Capability” under the MEXT's scheme entitled “Initiatives for Attractive Education in Graduate Schools”. Maturation of society and life, globalization of manufacturing industry, latest demands of human's welfare have changed the meaning of design from functional ensureance to value creation. This requests graduate education of mechanical engineering to turn its definition over both synthesis and analysis and to learning and communication capabilities beyond knowledge itself. With recognizing such a background, the program aims to reform the education curriculum of mechanical engineering by introducing a product design subject which integrates design methodology education and project-based learning over industry- sponsored design problems, several graduate-level fundamental subjects, and the depth area system in which elective subjects are categorized into several areas based on their specialty. This paper describes the objectives, undertakings, promises, etc. of the program.

  15. A review on , (10th Edition)%《Engineering Mechanics--Statics》,《Engineering Mechanics Dynamics》(10th Edition)评介

    Institute of Scientific and Technical Information of China (English)

    谢传锋

    2005-01-01

    @@ R.C.Hibbeler编著、(第10版)(Engineering MechanicsStatics,Engineering Mechanics--Dynamics(10th Edition),Prenties Hall,2003)已于2004年1月由高等教育出版社出版了影印版.该教材对我国的理论力学教材建设和双语教学具有极大参考价值.

  16. Mechanical Design Engineering Enabler Project wheel and wheel drives

    Science.gov (United States)

    Nutt, Richard E.; Couch, Britt K.; Holley, John L., Jr.; Garris, Eric S.; Staut, Paul V.

    1992-01-01

    Our group was assigned the responsibility of designing the wheel and wheel drive system for a proof-of-concept model of the lunar-based ENABLER. ENABLER is a multi-purpose, six wheeled vehicle designed to lift and transport heavy objects associated with the construction of a lunar base. The resulting design was based on the performance criteria of the ENABLER. The drive system was designed to enable the vehicle to achieve a speed of 7 mph on a level surface, climb a 30 percent grade, and surpass a one meter high object and one meter wide crevice. The wheel assemblies were designed to support the entire weight of the vehicle on two wheels. The wheels were designed to serve as the main component of the vehicle's suspension and will provide suitable traction for lunar-type surfaces. The expected performance of the drive system for the ENABLER was influenced by many mechanical factors. The expected top speed on a level sandy surface is 4 mph instead of the desired 7 mph. This is due to a lack of necessary power at the wheels. The lack of power resulted from dimension considerations that allowed only an eight horsepower engine and also from mechanical inefficiencies of the hydraulic system. However, the vehicle will be able to climb a 30 percent grade, surpass a one meter high object and one meter wide crevice. The wheel assemblies will be able to support the entire weight of the vehicle on two wheels. The wheels will also provide adequate suspension for the vehicle and sufficient traction for lunar-type surfaces.

  17. Stimulation of bone repair with ultrasound: a review of the possible mechanic effects.

    Science.gov (United States)

    Padilla, Frédéric; Puts, Regina; Vico, Laurence; Raum, Kay

    2014-07-01

    dish walls and the formation of standing waves will greatly affect the local type and amplitude of the stimulus exerted on the cells. A future engineering challenge is therefore the design of dedicated experimental set-ups, in which the different mechanical phenomena induced by ultrasound can be controlled. This is a prerequisite to evaluate the biological effects of the different phenomena with respect to particular parameters, like intensity, frequency, or duty cycle. By relating the variations of these parameters to the induced physical effects and to the biological responses, it will become possible to derive an 'acoustic dose' and propose a quantification and cross-calibration of the different experimental systems. Improvements in bone healing management will probably also come from a combination of ultrasound with a 'biologic' components, e.g. growth factors, scaffolds, gene therapies, or drug delivery vehicles, the effects of which being potentiated by the ultrasound.

  18. The interplay among chromatin dynamics, cell cycle checkpoints and repair mechanisms modulates the cellular response to DNA damage.

    Science.gov (United States)

    Lazzaro, Federico; Giannattasio, Michele; Muzi-Falconi, Marco; Plevani, Paolo

    2007-06-01

    Cells are continuously under the assault of endogenous and exogenous genotoxic stress that challenges the integrity of DNA. To cope with such a formidable task cells have evolved surveillance mechanisms, known as checkpoints, and a variety of DNA repair systems responding to different types of DNA lesions. These lesions occur in the context of the chromatin structure and, as expected for all DNA transactions, the cellular response to DNA damage is going to be influenced by the chromatin enviroment. In this review, we will discuss recent studies implicating chromatin remodelling factors and histone modifications in the response to DNA double-strand breaks (DSBs) and in checkpoint activation in response to UV lesions.

  19. Mechanical Engineering of the Linac for the Spallation Neutron Source

    Energy Technology Data Exchange (ETDEWEB)

    Bultman, N.K.; Chen, Z.; Collier, M.; Erickson, J.L.; Guthrie, A.; Hunter, W.T.; Ilg, T.; Meyer, R.K.; Snodgrass, N.L.

    1999-03-29

    The linac for the Spallation Neutron Source (SNS) Project will accelerate an average current of 1 mA of H{sup {minus}} ions from 20 MeV to 1GeV for injection into an accumulator ring. The linac will be an intense source of H{sup {minus}} ions and as such requires advanced design techniques to meet project technical goals as well as to minimize costs. The DTL, CCDTL and CCL are 466m long and operate at 805 MHz with a maximum H{sup {minus}} input current of 28 mA and 7% rf duty factor. The Drift Tube Linac is a copper-plated steel structure using permanent magnetic quadrupoles. The Coupled-Cavity portions are brazed copper structures and use electromagnetic quads. RF losses in the copper are 80 MW, with total rf power supplied by 52 klystrons. Additionally, the linac is to be upgraded to the 2- and 4-MW beam power levels with no increase in duty factor. The authors give an overview of the linac mechanical engineering effort and discuss the special challenges and status of the effort.

  20. Dynamics and mechanism of UV-damaged DNA repair in indole-thymine dimer adduct: molecular origin of low repair quantum efficiency.

    Science.gov (United States)

    Guo, Xunmin; Liu, Zheyun; Song, Qinhua; Wang, Lijuan; Zhong, Dongping

    2015-02-26

    Many biomimetic chemical systems for repair of UV-damaged DNA showed very low repair efficiency, and the molecular origin is still unknown. Here, we report our systematic characterization of the repair dynamics of a model compound of indole-thymine dimer adduct in three solvents with different polarity. By resolving all elementary steps including three electron-transfer processes and two bond-breaking and bond-formation dynamics with femtosecond resolution, we observed the slow electron injection in 580 ps in water, 4 ns in acetonitrile, and 1.38 ns in dioxane, the fast back electron transfer without repair in 120, 150, and 180 ps, and the slow bond splitting in 550 ps, 1.9 ns, and 4.5 ns, respectively. The dimer bond cleavage is clearly accelerated by the solvent polarity. By comparing with the biological repair machine photolyase with a slow back electron transfer (2.4 ns) and a fast bond cleavage (90 ps), the low repair efficiency in the biomimetic system is mainly determined by the fast back electron transfer and slow bond breakage. We also found that the model system exists in a dynamic heterogeneous C-clamped conformation, leading to a stretched dynamic behavior. In water, we even identified another stacked form with ultrafast cyclic electron transfer, significantly reducing the repair efficiency. Thus, the comparison of the repair efficiency in different solvents is complicated and should be cautious, and only the dynamics by resolving all elementary steps can finally determine the total repair efficiency. Finally, we use the Marcus electron-transfer theory to analyze all electron-transfer reactions and rationalize all observed electron-transfer dynamics.

  1. Research on Repair Technology for Camshaft of Aviation Piston Engine%航空活塞发动机凸轮轴修理技术研究

    Institute of Scientific and Technical Information of China (English)

    冯世榕

    2015-01-01

    According to the repair for camshaft of the aviation piston engine, the influences of grinding camshaft on the profile line, the contact stress, the lubrication characteristics and the wear resistance are analyzed in this paper, and the feasibility of repair is then demonstrated.The key technology of camshaft repair is analyzed, while method of reverse measurement for the profile line and theoretical model of the profile line reconstruction are then presented, thus the theoretical instruction for the re-pair of camshaft is finally provided.%针对航空活塞发动机凸轮轴修理,分析了轮廓磨削对型线、接触应力、润滑特性以及耐磨性的影响,论证了修理的可行性。分析了凸轮轴修理的关键技术,提出了轮廓型线反求的测量方法和型线重构的理论模型,为凸轮轴的修理提供了理论指导。

  2. Mechanical characterization and non-linear elastic modeling of poly(glycerol sebacate) for soft tissue engineering.

    Science.gov (United States)

    Mitsak, Anna G; Dunn, Andrew M; Hollister, Scott J

    2012-07-01

    Scaffold tissue engineering strategies for repairing and replacing soft tissue aim to improve reconstructive and corrective surgical techniques whose limitations include suboptimal mechanical properties, fibrous capsule formation and volume loss due to graft resorption. An effective tissue engineering strategy requires a scaffolding material with low elastic modulus that behaves similarly to soft tissue, which has been characterized as a nonlinear elastic material. The material must also have the ability to be manufactured into specifically designed architectures. Poly(glycerol sebacate) (PGS) is a thermoset elastomer that meets these criteria. We hypothesize that the mechanical properties of PGS can be modulated through curing condition and architecture to produce materials with a range of stiffnesses. To evaluate this hypothesis, we manufactured PGS constructs cured under various conditions and having one of two architectures (solid or porous). Specimens were then tensile tested according to ASTM standards and the data were modeled using a nonlinear elastic Neo-Hookean model. Architecture and testing conditions, including elongation rate and wet versus dry conditions, affected the mechanical properties. Increasing curing time and temperature led to increased tangent modulus and decreased maximum strain for solid constructs. Porous constructs had lower nonlinear elastic properties, as did constructs of both architectures tested under simulated physiological conditions (wetted at 37 °C). Both solid and porous PGS specimens could be modeled well with the Neo-Hookean model. Future studies include comparing PGS properties to other biological tissue types and designing and characterizing PGS scaffolds for regenerating these tissues.

  3. Characterization of the mechanical properties and structural integrity of T-welded connections repaired by grinding and wet welding

    Energy Technology Data Exchange (ETDEWEB)

    Terán, G., E-mail: gteran@imp.mx [Instituto Mexicano del Petróleo, Eje central Lázaro Cárdenas 152, Col. San Bartolo Atepehuacan, México D.F. CP 07730, México (Mexico); Cuamatzi-Meléndez, R., E-mail: rcuamatzi@imp.mx [Instituto Mexicano del Petróleo, Eje central Lázaro Cárdenas 152, Col. San Bartolo Atepehuacan, México D.F. CP 07730, México (Mexico); Albiter, A., E-mail: aalbiter@imp.mx [Instituto Mexicano del Petróleo, Eje central Lázaro Cárdenas 152, Col. San Bartolo Atepehuacan, México D.F. CP 07730, México (Mexico); Maldonado, C., E-mail: cmzepeda@umich.mx [Instituto de Investigaciones Metalúrgicas, UMSNH, PO Box 52-B, 58000, México (Mexico); Bracarense, A.Q., E-mail: bracarense@ufmg.br [UFMG Departamento de Engeharia Mecánica Belo Horizonte, MG (Brazil)

    2014-04-01

    This paper presents an experimental methodology to characterize the structural integrity and mechanical properties of repaired T-welded connections using in fixed offshore structures. Grinding is employed to remove localized damage like cracking and corrosion and subsequent wet welding can be used to fill the grinded material. But it is important to define the grinding depth and profile in order to maintain structural integrity during the repair. Therefore, in this work different grinding depths were performed, for damage material removal, at the weld toe of the T-welded connections. The grinding was filled by wet welding in a hyperbaric chamber, simulating three different water depths: 50 m, 70 m and 100 m. The electrodes were coated with vinilic varnish, which is cheap and easy to apply. The characterization of the mechanical properties of the T-welded connections was done with standard tensile, hardness and Charpy tests; microstructure and porosity analysis were also performed. The samples were obtained from the welded connections in regions of the wet weld beads. The test results were compared with the mechanical properties of the T-welded connections welded in air conditions performed by other authors. The results showed that the wet welding technique performed in this work produced good mechanical properties of the repaired T-welded connection. The mechanical properties, measured in wet conditions, for 6 mm grinding depth, were similar for the 3 different water depths measured in air conditions. But for 10 mm grinding depth, the values of the mechanical properties measured in wet conditions were quite lower than that for air conditions for the 3 water depths. However a porosity analysis, performed with a Scanning Electronic Microscopy (SEM), showed that the level of porosity in the resulted wet weld beads is in the range of that published in the literature and some samples revealed lower level of porosity. The main resulting microstructure was polygonal

  4. 骨缺损修复生物工程研究进展%Research progress of biological engineering on bone defect repairing

    Institute of Scientific and Technical Information of China (English)

    郭宜姣; 李文华

    2014-01-01

    complications after conventional treatment, including immune rejection, bad osteogenesis, disunion of bone fractures, and long-term pain caused by nerve injury.These reasons restrict the research of bone defect to some degree.Only based on the mechanism of bone repairing and growth, combining multiple methods, filling disadvantages from each other, and finding breakthroughs, we can improve the treatment of bone defect, shorten the treatment time, and improve patient ’ s quality of life.This paper briefly describes the advantages and disadvantages of autograft and allograft in the treatment of bone defect and emphasizes the research hotspots of bone tissue engineering and gene engineering in recent years, including the up-grading of biological materials, the increased quantity of target cells, and the research progress in growth factors and gene carriers.This papwer also discusses the advantages and disadvantages of these two methods in biological engineering to repair bone defect, illustrates the complement when they are applicated together, and finally puts forward the new ideas and new problems of the direction of bone defect research.

  5. Bacterial radiosensitivity to gamma and ultraviolet. Compositional dependence and repair mechanisms; Radiosensibilidad bacteriana frente a gamma y ultravioleta. Dependencia composicional y mecanismos de reparacion

    Energy Technology Data Exchange (ETDEWEB)

    Saez Angulo, R. M.; Davila, C. A.

    1974-07-01

    The gamma and ultraviolet radiosensitivity of several species of bacteria has been determined its dependence on DNAs composition and repair processes has been studied. Base composition are evaluated by chromatography, DNA melting temperature and isopycnic sedimentation on CsCl gradient. Repair capacity of gamma -and UV- lesions has been studied in two bacterial strains with same DMA base composition. It is concluded that the postulated correlation between radiosensitivity and base composition can not be generalized, the enzymatic repair mechanisms being of determining on radiosensitivity. (Author) 248 refs.

  6. NASA GSFC Mechanical Engineering Latest Inputs for Verification Standards (GEVS) Updates

    Science.gov (United States)

    Kaufman, Daniel

    2003-01-01

    This viewgraph presentation provides information on quality control standards in mechanical engineering. The presentation addresses safety, structural loads, nonmetallic composite structural elements, bonded structural joints, externally induced shock, random vibration, acoustic tests, and mechanical function.

  7. NASA GSFC Mechanical Engineering Latest Inputs for Verification Standards (GEVS) Updates

    Science.gov (United States)

    Kaufman, Daniel

    2003-01-01

    This viewgraph presentation provides information on quality control standards in mechanical engineering. The presentation addresses safety, structural loads, nonmetallic composite structural elements, bonded structural joints, externally induced shock, random vibration, acoustic tests, and mechanical function.

  8. Mechanical behavior of materials engineering methods for deformation, fracture, and fatigue

    CERN Document Server

    Dowling, Norman E

    2012-01-01

    For upper-level undergraduate engineering courses in Mechanical Behavior of Materials. Mechanical Behavior of Materials, 4/e introduces the spectrum of mechanical behavior of materials, emphasizing practical engineering methods for testing structural materials to obtain their properties, and predicting their strength and life when used for machines, vehicles, and structures. With its logical treatment and ready-to-use format, it is ideal for upper-level undergraduate students who have completed elementary mechanics of materials courses.

  9. Preparation, bioactivity and mechanism of nano-hydroxyapatite/sodium alginate/chitosan bone repair material.

    Science.gov (United States)

    Liao, Jianguo; Li, Yanqun; Li, Haiyan; Liu, Jingxian; Xie, Yufen; Wang, Jianping; Zhang, Yongxiang

    2017-08-11

    As the major inorganic component of natural bone, nano-hydroxyapatite (n-HA) on its own is limited in its use in bone repair, due to its brittleness. Chitosan (CS) and sodium alginate (SAL) are used to reduce its brittleness and tendency to degradation. However, the compressive strength of the composite is still low, and its biological performance needs further study. Nano-hydroxyapatite/sodium alginate/chitosan (n-HA/SAL/CS) composite was prepared via an in situ synthesis method. Further, we prepared the n-HA/SAL/CS self-setting bone repair material by mixing n-HA/SAL/CS powder with a curing liquid (20 wt.% citric acid). In addition, the in vitro bioactivity and cell cytotoxicity were also explored. Transmission electron microscopy photos revealed that the n-HA crystals were uniformly distributed throughout the polymer matrix. Infrared IR spectroscopy indicated that the HA interacted with the COO- of SAL and NH2- of CS. The compressive strength of the n-HA/SAL/CS bone cement was 34.3 MPa and matched the demands of weight-bearing bones. Soaking in vitro in simulated body fluid demonstrated that the composite material had reasonably good bioactivity, while cytotoxicity tests indicated that the n-HA/SAL/CS cement could promote cell proliferation and was biocompatible. Compressive strength of n-HA/SAL/CS can satisfy the needs of cancellous bone, and in vitro bioactivity and cytotoxicity tests results indicated that the n-HA/SAL/CS composite could act as an optimal bone repair material.

  10. Development of an integrated engine-hydro-mechanical transmission control algorithm for a tractor

    Directory of Open Access Journals (Sweden)

    Sunghyun Ahn

    2015-07-01

    Full Text Available This article presents an integrated engine-hydro-mechanical transmission control algorithm for a tractor considering the engine-hydro-mechanical transmission efficiency. First, the hydro-mechanical transmission efficiency was obtained by network analysis based on the hydrostatic unit efficiency constructed from the test. Using the hydro-mechanical transmission efficiency map and the thermal efficiency of the engine, an engine-hydro-mechanical transmission optimal operating line was obtained, which provides higher total system efficiency. Based on the optimal operating line, an integrated engine-hydro-mechanical transmission control algorithm was proposed, which provides higher total powertrain system efficiency. To evaluate the performance of the proposed control algorithm, an AMESim-MATLAB/Simulink-based co-simulator was developed. From the simulation results for the plow working, it was found that the integrated engine-hydro-mechanical transmission control provides improved fuel economy by 7.5% compared with the existing engine optimal operating line control. The performance of the integrated engine-hydro-mechanical transmission control was also validated using the test bench.

  11. Quarterly Bulletin of the Division of Mechanical Engineering and the National Aeronautical Establishment, Ottawa, 1 April to 30 June, 1976.

    Science.gov (United States)

    EXPERIMENTAL DESIGN, PSYCHOMOTOR FUNCTION, CANADA, TEST METHODS, MODULES(ELECTRONICS), PATTERNS, MECHANICAL ENGINEERING , SYSTEMS ANALYSIS, HANDBOOKS, AERONAUTICAL ENGINEERING, SLEEP, FATIGUE(PHYSIOLOGY).

  12. Reducing barriers to energy efficiency in the German mechanical engineering sector. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Schleich, J.; Boede, U.

    2000-12-01

    This report describes the empirical research into barriers to energy efficiency in the German mechanical engineering (ME) sector. It is one of nine such reports in the BARRIERS project. The report contains description and analysis of four case studies of energy management in German companies in the ME sector. The results are analysed using the theoretical framework developed for the BARRIERS project. The report also provides brief recommendations on how these barriers to the rational use of energy (RUE) may be overcome and how energy efficiency within the ME sector may be improved. The results of the study for the ME sector in Germany are summarised in this executive summary under the following headings: - Characterising the mechanical engineering sector; - Case studies of energy management in the German mechanical engineering sector; - Evidence of barriers in the German mechanical engineering sector; - The role of energy service companies in the mechanical engineering sector; - Policy implications. (orig.)

  13. Reducing barriers to energy efficiency in the German mechanical engineering sector. Executive summary

    Energy Technology Data Exchange (ETDEWEB)

    Schleich, J.; Boede, U.

    2000-12-01

    This report describes the empirical research into barriers to energy efficiency in the German mechanical engineering (ME) sector. It is one of nine such reports in the BARRIERS project. The report contains description and analysis of four case studies of energy management in German companies in the ME sector. The results are analysed using the theoretical framework developed for the BARRIERS project. The report also provides brief recommendations on how these barriers to the rational use of energy (RUE) may be overcome and how energy efficiency within the ME sector may be improved. The results of the study for the ME sector in Germany are summarised in this executive summary under the following headings: - Characterising the mechanical engineering sector; - Case studies of energy management in the German mechanical engineering sector; - Evidence of barriers in the German mechanical engineering sector; - The role of energy service companies in the mechanical engineering sector; - Policy implications. (orig.)

  14. Study of nozzle deposit formation mechanism for direct injection gasoline engines; Chokufun gasoline engine yo nozzle no deposit seisei kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Kinoshita, M.; Saito, A. [Toyota Central Research and Development Labs., Inc., Aichi (Japan); Matsushita, S. [Toyota Motor Corp., Aichi (Japan); Shibata, H. [Nippon Soken, Inc., Tokyo (Japan); Niwa, Y. [Denso Corp., Aichi (Japan)

    1997-10-01

    Nozzles in fuel injectors for direct injection gasoline engines are exposed to high temperature combustion gases and soot. In such a rigorous environment, it is a fear that fuel flow rate changes in injectors by deposit formation on nozzles. Fundamental factors of nozzle deposit formation were investigated through injector bench tests and engine dynamometer tests. Deposit formation processes were observed by SEM through engine dynamometer tests. The investigation results reveal nozzle deposit formation mechanism and how to suppress the deposit. 4 refs., 8 figs., 3 tabs.

  15. Divergent impact of Toll-like receptor 2 deficiency on repair mechanisms in healthy muscle versus Duchenne muscular dystrophy.

    Science.gov (United States)

    Mojumdar, Kamalika; Giordano, Christian; Lemaire, Christian; Liang, Feng; Divangahi, Maziar; Qureshi, Salman T; Petrof, Basil J

    2016-05-01

    Injury to skeletal muscle, whether acute or chronic, triggers macrophage-mediated innate immunity in a manner which can be either beneficial or harmful for subsequent repair. Endogenous ligands for Toll-like receptor 2 (TLR2) are released by damaged tissues and might play an important role in activating the innate immune system following muscle injury. To test this hypothesis, we compared macrophage behaviour and muscle repair mechanisms in mice lacking TLR2 under conditions of either acute (cardiotoxin-induced) or chronic (mdx mouse genetic model of Duchenne muscular dystrophy; DMD) muscle damage. In previously healthy muscle subjected to acute damage, TLR2 deficiency reduced macrophage numbers in the muscle post-injury but did not alter the expression pattern of the prototypical macrophage polarization markers iNOS and CD206. In addition, there was abnormal persistence of necrotic fibres and impaired regeneration in TLR2-/- muscles after acute injury. In contrast, TLR2 ablation in chronically diseased muscles of mdx mice not only resulted in significantly reduced macrophage numbers but additionally modified their phenotype by shifting from inflammatory (iNOS(pos) CD206(neg) ) to more anti-inflammatory (iNOS(neg) CD206(pos) ) characteristics. This decrease in macrophage-mediated inflammation was associated with ameliorated muscle histopathology and improved force-generating capacity of the dystrophic muscle. Our results suggest that the role of TLR2 in macrophage function and skeletal muscle repair depends greatly upon the muscle injury context, and raise the possibility that inhibition of TLR2 could serve as a useful therapeutic measure in DMD.

  16. Relationship among the repair mechanisms and the genetic recombination; Relacion entre los mecanismos de reparacion y la recombinacion genetica

    Energy Technology Data Exchange (ETDEWEB)

    Alcantara D, D. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    1987-12-15

    In accordance with the previous reports of the Project BZ87 of the Department of Radiobiology, a dependent stimulation of the system exists in E.coli SOS, of the recombination of the bacteriophage Lambda whose genetic material has not been damaged. This stimulation is not due to the increase of the cellular concentration of the protein RecA and the mechanism but probable for which we find that it is carried out, it is through a cooperation among the product of the gene rec N of E. coli and the system Net of recombination of Lambda. The gene recN belongs to the group of genes SOS and its expression is induced when damaging the bacterial DNA where it intervenes in the repair of breaks of the double helix of the molecule (Picksley et, 1984). If the repair of breaks of this type is a factor that limits the speed with which it happens the recombination among viral chromosomes, then the biggest readiness in the protein RecN, due to the induction of the functions SOS, would facilitate the repair of such ruptures. In this new project it is to enlarge the knowledge about this phenomenon, it was, on one hand of corroborating in a way but he/she specifies the relationship between the recombinogenic response of Lambda and the System SOS of E. coli and for the other one to determine the effect that has the inhibition of the duplication of the DNA on the stimulation of the viral recombination. Everything it with the idea of making it but evident and to be able to use it as a system of genotoxic agents detection in E. coli. (Author)

  17. Design of tissue engineering scaffolds as delivery devices for mechanical and mechanically modulated signals.

    Science.gov (United States)

    Anderson, Eric J; Knothe Tate, Melissa L

    2007-10-01

    New approaches to tissue engineering aim to exploit endogenous strategies such as those occurring in prenatal development and recapitulated during postnatal healing. Defining tissue template specifications to mimic the environment of the condensed mesenchyme during development allows for exploitation of tissue scaffolds as delivery devices for extrinsic cues, including biochemical and mechanical signals, to drive the fate of mesenchymal stem cells seeded within. Although a variety of biochemical signals that modulate stem cell fate have been identified, the mechanical signals conducive to guiding pluripotent cells toward specific lineages are less well characterized. Furthermore, not only is spatial and temporal control of mechanical stimuli to cells challenging, but also tissue template geometries vary with time due to tissue ingrowth and/or scaffold degradation. Hence, a case study was carried out to analyze flow regimes in a testbed scaffold as a first step toward optimizing scaffold architecture. A pressure gradient was applied to produce local (nm-micron) flow fields conducive to migration, adhesion, proliferation, and differentiation of cells seeded within, as well as global flow parameters (micron-mm), including flow velocity and permeability, to enhance directed cell infiltration and augment mass transport. Iterative occlusion of flow channel dimensions was carried out to predict virtually the effect of temporal geometric variation (e.g., due to tissue development and growth) on delivery of local and global mechanical signals. Thereafter, insights from the case study were generalized to present an optimization scheme for future development of scaffolds to be implemented in vitro or in vivo. Although it is likely that manufacture and testing will be required to finalize design specifications, it is expected that the use of the rational design optimization will reduce the number of iterations required to determine final prototype geometries and flow

  18. Abstracts of the Conference on Mechanisms of DNA Repair and Mutagenesis on the 100. Anniversary of the Discovery of Polonium and Radium

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    The conference covered various aspects of mutagenesis and mechanisms of DNA repair. UV and ionizing radiation were use to induce DNA lesions in bacteria, yeast and cell cultures of higher organisms. This allows study of influence of mutations on particular processes in the cell. Mechanisms of resistance were also investigated. Biological investigations were performed using labelled compounds.

  19. [Research on effects of vitamin A palmitate on repair of mechanical corneal epithelial defects and conjunctival goblet cells in rabbits].

    Science.gov (United States)

    Qiu, Xiao-di; Gong, Lan; Chen, Min-jie

    2010-02-01

    Randomized controlled experimental study to investigate the influence of vitamin A palmitate and bovine recombinant basic fibroblast growth factor (bFGF) on repair of mechanical corneal epithelial defects, conjunctival epithelial cells and goblet cells in rabbits. One hundred and twenty New Zealand rabbits (all males) were selected to establish the mechanical corneal epithelial defects models (scratching out a round area with the diameter of 8 mm in the centre of cornea). Forty eight New Zealand rabbits were randomly divided into 4 groups: group A used lincomycin hydrochloride eye drops (LED) after the model had been established; group B used vitamin A palmitate eye gel and LED; group C used recombinant bFGF eye gel and LED; group D used vitamin A palmitate eye gel, bFGF eye gel and LED. Photo slit lamp examination and measurement of repaired area were performed on day 0, day 1, day 4 and day 7; transmission electron microscopy, histological microscope examination and impression cytology were performed on day 0, day 1, day 4 and day 7 to analysis the morphology and repairment of corneal epithelium, conjunctival epithelial cells and the goblet cells. The variants were tested using analysis of variance and Tukey's test. Statistic analysis showed that on day 1, the size of areas of repaired corneal epithelium was: group A(53.512 +/- 18.850) mm(2), group B (92.194 +/- 14.367) mm(2), group C (89.779 +/- 20.535) mm(2), group D (127.816 +/- 16.379) mm(2). The difference in size of repaired areas between different groups was statistically significant (F = 17.663, P = 0.000), with exception of the difference between groups B and C (P = 0.995). Conjunctival impression cytology showed that, the average number of conjunctival goblet cells per 740 microm x 550 microm at day 1 was decreased, group A (10.083 +/- 4.441), group B (10.667 +/- 3.551), group C (9.583 +/- 4.502), group D (9.167 +/- 5.606). The difference between these four groups was not significant (F = 0.239, P = 0

  20. Constitutional Chromothripsis Rearrangements Involve Clustered Double-Stranded DNA Breaks and Nonhomologous Repair Mechanisms

    Directory of Open Access Journals (Sweden)

    Wigard P. Kloosterman

    2012-06-01

    Full Text Available Chromothripsis represents a novel phenomenon in the structural variation landscape of cancer genomes. Here, we analyze the genomes of ten patients with congenital disease who were preselected to carry complex chromosomal rearrangements with more than two breakpoints. The rearrangements displayed unanticipated complexity resembling chromothripsis. We find that eight of them contain hallmarks of multiple clustered double-stranded DNA breaks (DSBs on one or more chromosomes. In addition, nucleotide resolution analysis of 98 breakpoint junctions indicates that break repair involves nonhomologous or microhomology-mediated end joining. We observed that these eight rearrangements are balanced or contain sporadic deletions ranging in size between a few hundred base pairs and several megabases. The two remaining complex rearrangements did not display signs of DSBs and contain duplications, indicative of rearrangement processes involving template switching. Our work provides detailed insight into the characteristics of chromothripsis and supports a role for clustered DSBs driving some constitutional chromothripsis rearrangements.

  1. Fluid mechanics for mechanical engineering. Technology and examples; Stroemungslehre fuer den Maschinenbau. Technik und Beispiele

    Energy Technology Data Exchange (ETDEWEB)

    Siekmann, H.E. [Technische Univ. Berlin (Germany). Hermann-Foettinger-Institut fuer Stroemungsmechanik

    2001-07-01

    The book complements the established fluid mechanics textbook. It discusses the same subjects but goes into more detail and contains many practical examples. It addresses students of engineering, physics and practically oriented mathematics and can be used for independent studying or for a deeper understanding of subject matter treated in university lectures. [German] Der Band stellt als Ergaenzung zum eingefuehrten Grundlagenbuch Stroemungslehre eine tiefergehende Behandlung des Vorlesungsstoffes dar. Die Einteilung der Kapitel entspricht im wesentlichen der im Band Grundlagen: Hydrostatik, Kinematik, Impulssatz, NAVIER-Stokes-Bewegungsgleichung, Potential-, Wirbel- und Grenzschichtstroemung sowie turbulente Stroemung. Das Buch schliesst mit Darstellungen ueber Rohrstroemungen, Umstroemungen von Koerpern, Aehnlichkeitsgesetzen und numerische Stroemungsberechnung. Es enthaelt zahlreiche Praxisbeispiele. Geeignet fuer Studenten der Ingenieurwissenschaften, Physiker und praxisorientierte Mathematiker zum Selbststudium sowie zur Vorlesungsbegleitung. (orig.)

  2. A Comparison of the mechanical engineering and safety engineering student’s ICT attitudes at the Obuda University

    Directory of Open Access Journals (Sweden)

    Kiss Gabor

    2016-01-01

    Full Text Available Communication and technology are critical to education. However, using technology in education is not an easy task as communication barriers emerge. The aim of this research is to analyze the ICT attitudes from different faculties at the Obuda University that is between the mechanical engineering students and safety engineering students from the Donát Bánki Mechanical Safety Engineer Faculty. The students from these two groups will use different ICT tool at work after their graduation; the mechanical engineering students will work mostly with designer ICT tools, the safety engineering students will use security systems. It would be important to know whether instructors, when using ICT, have to follow different teaching methods and approaches in these two different groups or not. We measured the ICT attitude with a tool consisting of 23 items (Likert scaled. We worked with 361 students. The data analysis was performed with SPSS software using descriptive statistics and Mann-Whitney test. The results show both groups having the same positive ICT attitude however with one difference.

  3. An evaluation of Admedus' tissue engineering process-treated (ADAPT) bovine pericardium patch (CardioCel) for the repair of cardiac and vascular defects.

    Science.gov (United States)

    Strange, Geoff; Brizard, Christian; Karl, Tom R; Neethling, Leon

    2015-03-01

    Tissue engineers have been seeking the 'Holy Grail' solution to calcification and cytotoxicity of implanted tissue for decades. Tissues with all of the desired qualities for surgical repair of congenital heart disease (CHD) are lacking. An anti-calcification tissue engineering process (ADAPT TEP) has been developed and applied to bovine pericardium (BP) tissue (CardioCel, AdmedusRegen Pty Ltd, Perth, WA, Australia) to eliminate cytotoxicity, improve resistance to acute and chronic inflammation, reduce calcification and facilitate controlled tissue remodeling. Clinical data in pediatric patients, and additional pre-market authorized prescriber data demonstrate that CardioCel performs extremely well in the short term and is safe and effective for a range of congenital heart deformations. These data are supported by animal studies which have shown no more than normal physiologic levels of calcification, with good durability, biocompatibility and controlled healing.

  4. Mechanics of oriented electrospun nanofibrous scaffolds for annulus fibrosus tissue engineering.

    Science.gov (United States)

    Nerurkar, Nandan L; Elliott, Dawn M; Mauck, Robert L

    2007-08-01

    Engineering a functional replacement for the annulus fibrosus (AF) of the intervertebral disc is contingent upon recapitulation of AF structure, composition, and mechanical properties. In this study, we propose a new paradigm for AF tissue engineering that focuses on the reconstitution of anatomic fiber architecture and uses constitutive modeling to evaluate construct function. A modified electrospinning technique was utilized to generate aligned nanofibrous polymer scaffolds for engineering the basic functional unit of the AF, a single lamella. Scaffolds were tested in uniaxial tension at multiple fiber orientations, demonstrating a nonlinear dependence of modulus on fiber angle that mimicked the nonlinearity and anisotropy of native AF. A homogenization model previously applied to native AF successfully described scaffold mechanical response, and parametric studies demonstrated that nonfibrillar matrix, along with fiber connectivity, are key contributors to tensile mechanics for engineered AF. We demonstrated that AF cells orient themselves along the aligned scaffolds and deposit matrix that contributes to construct mechanics under loading conditions relevant to the in vivo environment. The homogenization model was applied to cell-seeded constructs and provided quantitative measures for the evolution of matrix and interfibrillar interactions. Finally, the model demonstrated that at fiber angles of the AF (28 degrees -44 degrees ), engineered material behaved much like native tissue, suggesting that engineered constructs replicate the physiologic behavior of the single AF lamella. Constitutive modeling provides a powerful tool for analysis of engineered AF neo-tissue and native AF tissue alike, highlighting key mechanical design criteria for functional AF tissue engineering.

  5. Thermal and Mechanical Design Aspects of the LIFE Engine

    Energy Technology Data Exchange (ETDEWEB)

    Abbott, R P; Gerhard, M A; Latkowski, J F; Kramer, K J; Morris, K R; Peterson, P F; Seifried, J E

    2008-10-25

    The Laser Inertial confinement fusion - Fission Energy (LIFE) engine encompasses the components of a LIFE power plant responsible for converting the thermal energy of fusion and fission reactions into electricity. The design and integration of these components must satisfy a challenging set of requirements driven by nuclear, thermal, geometric, structural, and materials considerations. This paper details a self-consistent configuration for the LIFE engine along with the methods and technologies selected to meet these stringent requirements. Included is discussion of plant layout, coolant flow dynamics, fuel temperatures, expected structural stresses, power cycle efficiencies, and first wall survival threats. Further research and to understand and resolve outstanding issues is also outlined.

  6. Comparative acoustic performance and mechanical properties of silk membranes for the repair of chronic tympanic membrane perforations.

    Science.gov (United States)

    Allardyce, Benjamin J; Rajkhowa, Rangam; Dilley, Rodney J; Xie, Zhigang; Campbell, Luke; Keating, Adrian; Atlas, Marcus D; von Unge, Magnus; Wang, Xungai

    2016-12-01

    The acoustic and mechanical properties of silk membranes of different thicknesses were tested to determine their suitability as a repair material for tympanic membrane perforations. Membranes of different thickness (10-100μm) were tested to determine their frequency response and their resistance to pressure loads in a simulated ear canal model. Their mechanical rigidity to pressure loads was confirmed by tensile testing. These membranes were tested alongside animal cartilage, currently the strongest available myringoplasty graft as well as paper, which is commonly used for simpler procedures. Silk membranes showed resonant frequencies within the human hearing range and a higher vibrational amplitude than cartilage, suggesting that silk may offer good acoustic energy transfer characteristics. Silk membranes were also highly resistant to simulated pressure changes in the middle ear, suggesting they can resist retraction, a common cause of graft failure resulting from chronic negative pressures in the middle ear. Part of this strength can be explained by the substantially higher modulus of silk films compared with cartilage. This allows for the production of films that are much thinner than cartilage, with superior acoustic properties, but that still provide the same level of mechanical support as thicker cartilage. Together, these in vitro results suggest that silk membranes may provide good hearing outcomes while offering similar levels of mechanical support to the reconstructed middle ear.

  7. Structure and stereochemistry of the base excision repair glycosylase MutY reveal a mechanism similar to retaining glycosidases.

    Science.gov (United States)

    Woods, Ryan D; O'Shea, Valerie L; Chu, Aurea; Cao, Sheng; Richards, Jody L; Horvath, Martin P; David, Sheila S

    2016-01-29

    MutY adenine glycosylases prevent DNA mutations by excising adenine from promutagenic 8-oxo-7,8-dihydroguanine (OG):A mismatches. Here, we describe structural features of the MutY active site bound to an azaribose transition state analog which indicate a catalytic role for Tyr126 and approach of the water nucleophile on the same side as the departing adenine base. The idea that Tyr126 participates in catalysis, recently predicted by modeling calculations, is strongly supported by mutagenesis and by seeing close contact between the hydroxyl group of this residue and the azaribose moiety of the transition state analog. NMR analysis of MutY methanolysis products corroborates a mechanism for adenine removal with retention of stereochemistry. Based on these results, we propose a revised mechanism for MutY that involves two nucleophilic displacement steps akin to the mechanisms accepted for 'retaining' O-glycosidases. This new-for-MutY yet familiar mechanism may also be operative in related base excision repair glycosylases and provides a critical framework for analysis of human MutY (MUTYH) variants associated with inherited colorectal cancer.

  8. Effects of suture position on left ventricular fluid mechanics under mitral valve edge-to-edge repair.

    Science.gov (United States)

    Du, Dongxing; Jiang, Song; Wang, Ze; Hu, Yingying; He, Zhaoming

    2014-01-01

    Mitral valve (MV) edge-to-edge repair (ETER) is a surgical procedure for the correction of mitral valve regurgitation by suturing the free edge of the leaflets. The leaflets are often sutured at three different positions: central, lateral and commissural portions. To study the effects of position of suture on left ventricular (LV) fluid mechanics under mitral valve ETER, a parametric model of MV-LV system during diastole was developed. The distribution and development of vortex and atrio-ventricular pressure under different suture position were investigated. Results show that the MV sutured at central and lateral in ETER creates two vortex rings around two jets, compared with single vortex ring around one jet of the MV sutured at commissure. Smaller total orifices lead to a higher pressure difference across the atrio-ventricular leaflets in diastole. The central suture generates smaller wall shear stresses than the lateral suture, while the commissural suture generated the minimum wall shear stresses in ETER.

  9. Virtual engineering tools supporting mechanical systems design and lifecycle management

    OpenAIRE

    Mozzillo, Rocco

    2015-01-01

    Currently Virtual Reality techniques are well developed in the scientific research field, but their massive application in industrial contexts is still a challenge. The main objective of the present work is developing a methodology able to integrate Virtual Reality engineering tools in the industrial contexts.

  10. Mechanical cues in orofacial tissue engineering and regenerative medicine

    NARCIS (Netherlands)

    Brouwer, K.M.; Lundvig, D.M.S.; Middelkoop, E.; Wagener, F.A.D.T.G.; Hoff, J.W. Von den

    2015-01-01

    Cleft lip and palate patients suffer from functional, aesthetical, and psychosocial problems due to suboptimal regeneration of skin, mucosa, and skeletal muscle after restorative cleft surgery. The field of tissue engineering and regenerative medicine (TE/RM) aims to restore the normal physiology of

  11. β1 integrin signaling in asymmetric migration of keratinocytes under mechanical stretch in a co-cultured wound repair model.

    Science.gov (United States)

    Lü, Dongyuan; Li, Zhan; Gao, Yuxin; Luo, Chunhua; Zhang, Fan; Zheng, Lu; Wang, Jiawen; Sun, Shujin; Long, Mian

    2016-12-28

    Keratinocyte (KC) migration in re-epithelization is crucial in repairing injured skin. But the mechanisms of how mechanical stimuli regulate the migration of keratinocytes have been poorly understood. Human immortalized keratinocyte HaCaT cells were co-cultured with skin fibroblasts on PDMS membranes and transferred to the static stretch device developed in-house for additional 6 day culture under mechanical stretch to mimic surface tension in skin. To detect the expression of proteins on different position at different time points and the effect of β1 integrin mechanotransduction on HaCaT migration, Immunofluorescence, Reverse transcription-polymerase chain reaction, Flow cytometry, Western blotting assays were applied. Mechanical receptor of β1 integrin that recognizes its ligand of collagen I was found to be strongly associated with migration of HaCaT cells since the knockdown of β1 integrin via RNA silence eliminated the key protein expression dynamically. Here the expression of vinculin was lower but that of Cdc42 was higher for the cells at outward edge than those at inward edge, respectively, supporting that the migration capability of keratinocytes is inversely correlated with the formation of focal adhesion complexes but positively related to the lamellipodia formation. This asymmetric expression feature was further confirmed by high or low expression of PI3K for outward- or inward-migrating cells. And ERK1/2 phosphorylation was up-regulated by mechanical stretch. We reported here, a novel mechanotransduction signaling pathways were β1 integrin-dependent pattern of keratinocytes migration under static stretch in an in vitro co-culture model. These results provided an insight into underlying molecular mechanisms of keratinocyte migration under mechanical stimuli.

  12. Intracellular Protein Shuttling: A Mechanism Relevant for Myelin Repair in Multiple Sclerosis?

    Directory of Open Access Journals (Sweden)

    Peter Göttle

    2015-07-01

    Full Text Available A prominent feature of demyelinating diseases such as multiple sclerosis (MS is the degeneration and loss of previously established functional myelin sheaths, which results in impaired signal propagation and axonal damage. However, at least in early disease stages, partial replacement of lost oligodendrocytes and thus remyelination occur as a result of resident oligodendroglial precursor cell (OPC activation. These cells represent a widespread cell population within the adult central nervous system (CNS that can differentiate into functional myelinating glial cells to restore axonal functions. Nevertheless, the spontaneous remyelination capacity in the adult CNS is inefficient because OPCs often fail to generate new oligodendrocytes due to the lack of stimulatory cues and the presence of inhibitory factors. Recent studies have provided evidence that regulated intracellular protein shuttling is functionally involved in oligodendroglial differentiation and remyelination activities. In this review we shed light on the role of the subcellular localization of differentiation-associated factors within oligodendroglial cells and show that regulation of intracellular localization of regulatory factors represents a crucial process to modulate oligodendroglial maturation and myelin repair in the CNS.

  13. Intracellular Protein Shuttling: A Mechanism Relevant for Myelin Repair in Multiple Sclerosis?

    Science.gov (United States)

    Göttle, Peter; Küry, Patrick

    2015-07-03

    A prominent feature of demyelinating diseases such as multiple sclerosis (MS) is the degeneration and loss of previously established functional myelin sheaths, which results in impaired signal propagation and axonal damage. However, at least in early disease stages, partial replacement of lost oligodendrocytes and thus remyelination occur as a result of resident oligodendroglial precursor cell (OPC) activation. These cells represent a widespread cell population within the adult central nervous system (CNS) that can differentiate into functional myelinating glial cells to restore axonal functions. Nevertheless, the spontaneous remyelination capacity in the adult CNS is inefficient because OPCs often fail to generate new oligodendrocytes due to the lack of stimulatory cues and the presence of inhibitory factors. Recent studies have provided evidence that regulated intracellular protein shuttling is functionally involved in oligodendroglial differentiation and remyelination activities. In this review we shed light on the role of the subcellular localization of differentiation-associated factors within oligodendroglial cells and show that regulation of intracellular localization of regulatory factors represents a crucial process to modulate oligodendroglial maturation and myelin repair in the CNS.

  14. CNS repair and axon regeneration: Using genetic variation to determine mechanisms.

    Science.gov (United States)

    Tedeschi, Andrea; Omura, Takao; Costigan, Michael

    2017-01-01

    The importance of genetic diversity in biological investigation has been recognized since the pioneering studies of Gregor Johann Mendel and Charles Darwin. Research in this area has been greatly informed recently by the publication of genomes from multiple species. Genes regulate and create every part and process in a living organism, react with the environment to create each living form and morph and mutate to determine the history and future of each species. The regenerative capacity of neurons differs profoundly between animal lineages and within the mammalian central and peripheral nervous systems. Here, we discuss research that suggests that genetic background contributes to the ability of injured axons to regenerate in the mammalian central nervous system (CNS), by controlling the regulation of specific signaling cascades. We detail the methods used to identify these pathways, which include among others Activin signaling and other TGF-β superfamily members. We discuss the potential of altering these pathways in patients with CNS damage and outline strategies to promote regeneration and repair by combinatorial manipulation of neuron-intrinsic and extrinsic determinants. Copyright © 2016 Elsevier Inc. All rights reserved.

  15. Structural basis for a novel mechanism of DNA bridging and alignment in eukaryotic DSB DNA repair.

    Science.gov (United States)

    Gouge, Jérôme; Rosario, Sandrine; Romain, Félix; Poitevin, Frédéric; Béguin, Pierre; Delarue, Marc

    2015-04-15

    Eukaryotic DNA polymerase mu of the PolX family can promote the association of the two 3'-protruding ends of a DNA double-strand break (DSB) being repaired (DNA synapsis) even in the absence of the core non-homologous end-joining (NHEJ) machinery. Here, we show that terminal deoxynucleotidyltransferase (TdT), a closely related PolX involved in V(D)J recombination, has the same property. We solved its crystal structure with an annealed DNA synapsis containing one micro-homology (MH) base pair and one nascent base pair. This structure reveals how the N-terminal domain and Loop 1 of Tdt cooperate for bridging the two DNA ends, providing a templating base in trans and limiting the MH search region to only two base pairs. A network of ordered water molecules is proposed to assist the incorporation of any nucleotide independently of the in trans templating base. These data are consistent with a recent model that explains the statistics of sequences synthesized in vivo by Tdt based solely on this dinucleotide step. Site-directed mutagenesis and functional tests suggest that this structural model is also valid for Pol mu during NHEJ.

  16. Half-bead weld repairs for in-service applications

    Energy Technology Data Exchange (ETDEWEB)

    Holz, P.P. Sr.

    1978-01-01

    Successful half- or temper-bead technique weld repairs performed to Section XI of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code guidelines were made to two Heavy-Section Steel Technology Program vessels and a qualification prolongation. Intermediate sized vessels, equivalent in thickness to nuclear pressure vessels, were repair welded and subsequently flawed and pressure tested to approximately 2/sup 1///sub 4/ times design pressure before leakage occurred. Discussed are the standards and procedures used with half-bead repairs, resultant induced metallurgical and stress effects, flaw test criterion, pressure test details and results, and recommendations for further development work for a speedier application process.

  17. In-situ engineering of cartilage repair: a pre-clinical in-vivo exploration of a novel system.

    Science.gov (United States)

    Seedhom, B B; Luo, Z-J; Goldsmith, A J; Toyoda, T; Lorrison, J C; Guardamagna, L

    2007-07-01

    This investigation explores a new cartilage repair technique that uses a novel method to secure a non-woven multifilamentous scaffold in the defect site after microfracture. The hypothesis is that a scaffold provides a larger surface area for attachment and proliferation of the mesenchymal stem cells that migrate from the bone marrow. Two in-vivo studies were undertaken in an ovine model. The first study, which lasted for 8 weeks, aimed to compare the new technique with microfracture. Chondral defects, 7 mm in diameter, were created in both femoral medial condyles of five ewes. One defect was treated with the new technique while the contralateral knee was treated with microfracture alone. The results revealed that the quantity of repair tissue was significantly greater in the defects treated with the new system. The second study had two time points, 3 and 6 months, and used 13 ewes. In this study, both defects were treated with the new technique but one received additional subchondral drilling in order to stimulate extra tissue growth. The majority of the implants had good tissue induction, filling 50-100 per cent of the defect volume, while the compressive modulus of the repairs was in the range of 40-70 per cent of that for the surrounding cartilage. In addition, hyaline-like cartilage was seen in all the repairs which had the additional drilling of the subchondral bone.

  18. Mechanical Stress Changes the Complex Interplay Between HO-1, Inflammation and Fibrosis, During Excisional Wound Repair

    NARCIS (Netherlands)

    Cremers, N.A.J.; Suttorp, M.; Gerritsen, M.M.; Wong, R.J.; Run-van Breda, C. van; Dam, G.M. van; Brouwer, K.M.; Kuijpers-Jagtman, A.M.; Carels, C.E.L.; Lundvig, D.M.; Wagener, F.A.D.T.G.

    2015-01-01

    Mechanical stress following surgery or injury can promote pathological wound healing and fibrosis, and lead to functional loss and esthetic problems. Splinted excisional wounds can be used as a model for inducing mechanical stress. The cytoprotective enzyme heme oxygenase-1 (HO-1) is thought to orch

  19. Molecular pathology of mismatch repair deficient tumours with emphasis on immune escape mechanisms

    NARCIS (Netherlands)

    Dierssen, Jan Willem Frederik

    2010-01-01

    This thesis describes molecular methods to distinguish separate colon tumour entities. Furthermore, it shows that distinct immune escape mechanisms, in particular distinct mechanisms of corrupting the HLA system, are operational in subsets of colon tumours. The apparent necessity of some colon tumou

  20. Curriculum Development Based on the Big Picture Assessment of the Mechanical Engineering Program

    Science.gov (United States)

    Sabri, Mohd Anas Mohd; Khamis, Nor Kamaliana; Tahir, Mohd Faizal Mat; Wahid, Zaliha; Kamal, Ahmad; Ihsan, Ariffin Mohd; Sulong, Abu Bakar; Abdullah, Shahrum

    2013-01-01

    One of the major concerns of the Engineering Accreditation Council (EAC) is the need for an effective monitoring and evaluation of program outcome domains that can be associated with courses taught under the Mechanical Engineering program. However, an effective monitoring method that can determine the results of each program outcome using Bloom's…

  1. Use of Concept Maps as an Assessment Tool in Mechanical Engineering Education

    Science.gov (United States)

    Tembe, B. L.; Kamble, S. K.

    2013-01-01

    The purpose of this study to investigate, how third year mechanical engineering students are able to use their knowledge of concept maps in their study of the topic of "Introduction to the Internal Combustion Engines (IICE)". 41 students participated in this study. Firstly, the students were taught about concept maps and then asked to…

  2. Cell-laden photocrosslinked GelMA-DexMA copolymer hydrogels with tunable mechanical properties for tissue engineering.

    Science.gov (United States)

    Wang, Hang; Zhou, Lei; Liao, Jingwen; Tan, Ying; Ouyang, Kongyou; Ning, Chenyun; Ni, Guoxin; Tan, Guoxin

    2014-09-01

    To effectively repair or replace damaged tissues, it is necessary to design three dimensional (3D) extracellular matrix (ECM) mimicking scaffolds with tunable biomechanical properties close to the desired tissue application. In the present work, gelatin methacrylate (GelMA) and dextran glycidyl methacrylate (DexMA) with tunable mechanical and biological properties were utilized to prepared novel bicomponent polymeric hydrogels by cross-linking polymerization using photoinitiation. We controlled the degree of substitution (DS) of glycidyl methacrylate in DexMA so that they could obtain relevant mechanical properties. The results indicated that copolymer hydrogels demonstrated a lower swelling ratio and higher compressive modulus as compared to the GelMA. Moreover, all of the hydrogels exhibited a honeycomb-like architecture, the pore sizes decreased as DS increased, and NIH-3T3 fibroblasts encapsulated in these hydrogels all exhibited excellent viability. These characteristics suggest a class of photocrosslinkable, tunable mechanically copolymer hydrogels that may find potential application in tissue engineering and regenerative medicine applications.

  3. Dynamic Mechanical and Nanofibrous Topological Combinatory Cues Designed for Periodontal Ligament Engineering.

    Science.gov (United States)

    Kim, Joong-Hyun; Kang, Min Sil; Eltohamy, Mohamed; Kim, Tae-Hyun; Kim, Hae-Won

    2016-01-01

    Complete reconstruction of damaged periodontal pockets, particularly regeneration of periodontal ligament (PDL) has been a significant challenge in dentistry. Tissue engineering approach utilizing PDL stem cells and scaffolding matrices offers great opportunity to this, and applying physical and mechanical cues mimicking native tissue conditions are of special importance. Here we approach to regenerate periodontal tissues by engineering PDL cells supported on a nanofibrous scaffold under a mechanical-stressed condition. PDL stem cells isolated from rats were seeded on an electrospun polycaprolactone/gelatin directionally-oriented nanofiber membrane and dynamic mechanical stress was applied to the cell/nanofiber construct, providing nanotopological and mechanical combined cues. Cells recognized the nanofiber orientation, aligning in parallel, and the mechanical stress increased the cell alignment. Importantly, the cells cultured on the oriented nanofiber combined with the mechanical stress produced significantly stimulated PDL specific markers, including periostin and tenascin with simultaneous down-regulation of osteogenesis, demonstrating the roles of topological and mechanical cues in altering phenotypic change in PDL cells. Tissue compatibility of the tissue-engineered constructs was confirmed in rat subcutaneous sites. Furthermore, in vivo regeneration of PDL and alveolar bone tissues was examined under the rat premaxillary periodontal defect models. The cell/nanofiber constructs engineered under mechanical stress showed sound integration into tissue defects and the regenerated bone volume and area were significantly improved. This study provides an effective tissue engineering approach for periodontal regeneration-culturing PDL stem cells with combinatory cues of oriented nanotopology and dynamic mechanical stretch.

  4. Engineering rock mechanics practices in the underground powerhouse at Jinping I hydropower station

    National Research Council Canada - National Science Library

    Aiqing Wu Jimin Wang Zhong Zhou Shuling Huang Xiuli Ding Zhihong Dong Yuting Zhang

    2016-01-01

    Based on the analyses of data obtained from the underground powerhouse at Jinping I hydropower station, a comprehensive review of engineering rock mechanics practice in the underground powerhouse is first conducted...

  5. Mechanical Engineering of Leg Joints of Anthropomorphic Robot

    Directory of Open Access Journals (Sweden)

    Pavluk Nikita

    2016-01-01

    Full Text Available The problem of design engineering of anthropomorphic robot legs is considered. An overview of the existing anthropomorphic robots and an analysis of servomechanisms and bearing parts involved in the assembly of robot legs are presented. We propose an option for constructing the legs of the robot Antares under development. A two-motor layout, used in the knee, ensures higher joint power along with independent interaction with the neighboring upper and lower leg joints when bending. To reduce the electrical load on the main battery of the robot, the upper legs are provided with a mounting pad for additional batteries powering servos. Direct control of the servos is also carried out through the sub-controllers, responsible for all 6 engines installed in the articular joints of the robot legs.

  6. DNA repair mechanism by photolyase: electron transfer path from the photolyase catalytic cofactor FADH(-) to DNA thymine dimer.

    Science.gov (United States)

    Medvedev, D; Stuchebrukhov, A A

    2001-05-21

    Photolyase is an enzyme that catalyses photorepair of thymine dimers in UV damaged DNA by electron transfer reaction. The structure of the photolyase/DNA complex is unknown at present. Using crystal structure coordinates of the substrate-free enzyme from E. coli, we have recently built a computer molecular model of a thymine dimer docked to photolyase catalytic site and studied molecular dynamics of the system. In this paper, we present analysis of the electronic coupling and electron transfer pathway between the catalytic cofactor FADH(-) and the pyrimidine dimer by the method of interatomic tunneling currents. Electronic structure is treated in the extended Hückel approximation. The root mean square transfer matrix element is about 6 cm(-1), which is consistent with the experimentally determined rate of transfer. We find that electron transfer mechanism responsible for the repair utilizes an unusual folded conformation of FADH(-) in photolyases, in which the isoalloxazine ring of the flavin and the adenine are in close proximity, and the peculiar features of the docked orientation of the dimer. The tunneling currents show explicitly that despite of the close proximity between the donor and acceptor complexes, the electron transfer mechanism between the flavin and the thymine bases is not direct, but indirect, with the adenine acting as an intermediate. These calculations confirm the previously made conclusion based on an indirect evidence for such mechanism.

  7. 小型柴油机的拆卸和装配修理分析研究%Small diesel engine repair disassembly and assembly analysis

    Institute of Scientific and Technical Information of China (English)

    高艳

    2013-01-01

    Building a new socialist countryside, agricultural machinery will be fully extended. Small diesel engines are the main power machinery in rural China,Small diesel engine has a simple structure, easy maintenance and cheap and so in rural economic life plays a significant role. However, because many users of small diesel engine construction, use and maintenance of knowledge mastered enough, use improper operation, maintenance timing is wrong, seriously affecting the efficiency of a small diesel engine into full play. For small diesel engine problems in use, the small diesel engine dis-assembly and assembly and repair of.%建设社会主义新农村,农用机械必将得到全面推广。小型柴油机是我国农村的主要动力机械,小型柴油机具有结构简单、使用维护方便和价格便宜等特点,在农村的经济生活中发挥着很大的作用。但是由于许多使用者对小型柴油机的构造、使用和维修知识掌握不够,使用操作不当、维护保养失时,严重影响着小型柴油机效率的充分发挥。针对小型柴油机在使用中存在的问题,文章对小型柴油机的拆卸和装配修理进行探析。

  8. Engineering Mathematics I : Electromagnetics, Fluid Mechanics, Material Physics and Financial Engineering

    CERN Document Server

    Rančić, Milica

    2016-01-01

    This book highlights the latest advances in engineering mathematics with a main focus on the mathematical models, structures, concepts, problems and computational methods and algorithms most relevant for applications in modern technologies and engineering. In particular, it features mathematical methods and models of applied analysis, probability theory, differential equations, tensor analysis and computational modelling used in applications to important problems concerning electromagnetics, antenna technologies, fluid dynamics, material and continuum physics and financial engineering. The individual chapters cover both theory and applications, and include a wealth of figures, schemes, algorithms, tables and results of data analysis and simulation. Presenting new methods and results, reviews of cutting-edge research, and open problems for future research, they equip readers to develop new mathematical methods and concepts of their own, and to further compare and analyse the methods and results discussed. The ...

  9. Prior Knowledge of Mechanics amongst First Year Engineering Students

    Science.gov (United States)

    Clements, Dick

    2007-01-01

    In the last 25 years, A-level Mathematics syllabi have changed very considerably, introducing a broader range of application areas but reducing the previous emphasis on classical mechanics. This article describes a baseline survey undertaken to establish in detail the entry levels in mechanics for the cohort of students entering Engineering…

  10. Asymmetric migration of human keratinocytes under mechanical stretch and cocultured fibroblasts in a wound repair model.

    Directory of Open Access Journals (Sweden)

    Dongyuan Lü

    Full Text Available Keratinocyte migration during re-epithelization is crucial in wound healing under biochemical and biomechanical microenvironment. However, little is known about the underlying mechanisms whereby mechanical tension and cocultured fibroblasts or keratinocytes modulate the migration of keratinocytes or fibroblasts. Here we applied a tensile device together with a modified transwell assay to determine the lateral and transmembrane migration dynamics of human HaCaT keratinocytes or HF fibroblasts. A novel pattern of asymmetric migration was observed for keratinocytes when they were cocultured with non-contact fibroblasts, i.e., the accumulative distance of HaCaT cells was significantly higher when moving away from HF cells or migrating from down to up cross the membrane than that when moving close to HF cells or when migrating from up to down, whereas HF migration was symmetric. This asymmetric migration was mainly regulated by EGF derived from fibroblasts, but not transforming growth factor α or β1 production. Mechanical stretch subjected to fibroblasts fostered keratinocyte asymmetric migration by increasing EGF secretion, while no role of mechanical stretch was found for EGF secretion by keratinocytes. These results provided a new insight into understanding the regulating mechanisms of two- or three-dimensional migration of keratinocytes or fibroblasts along or across dermis and epidermis under biomechanical microenvironment.

  11. Farm and Ranch Mechanical Repair and VEH Farm and Ranch Maintenance. Curriculum Guide for Agribusiness 121. Agricultural Mechanics.

    Science.gov (United States)

    Texas A and M Univ., College Station. Dept. of Agricultural Education.

    This curriculum guide provides materials for teachers to use in developing a 1- or 2-year course in agricultural mechanics for at-risk and special education students. It is one of 28 semester courses in agricultural science and technology for Texas high schools. The program prepares low-achieving students with employability skills that are…

  12. Analytical expression for an optimised link bar mechanism for a beta-type Stirling engine

    DEFF Research Database (Denmark)

    Carlsen, Henrik; Bovin, Jonas Kabell

    2007-01-01

    The design of a mechanism for kinematic beta-type Stirling engines, where the displacer piston and the working piston share the same cylinder, is complicated. A well-known solution is the rhombic drive, but this solution depends on oil lubrication because of the gear wheels connecting the two...... counter rotating crank shafts. In a hermetically sealed Stirling engine it is an advantage to avoid oil in the crank case, making the application of the rhombic drive difficult. In this paper, another crank mechanism is presented, which has been developed for a 9 kW single cylinder engine. The new crank...

  13. Numerical method to determine mechanical parameters of engineering design in rock masses

    Institute of Scientific and Technical Information of China (English)

    薛廷河; 项贻强; 郭发忠

    2004-01-01

    This paper proposes a new continuity model for engineering in rock masses and a new schematic method for reporting the engineering of rock continuity. This method can be used to evaluate the mechanics of every kind of medium;and is a new way to determine the mechanical parameters used in engineering design in rock masses. In the numerical simulation, the experimental parameters of intact rock were combined with the structural properties of field rock. Theexperimental results for orthogonally-jointed rock are given. The results included the curves of the stress-strain relationship of some rock masses, the curve of the relationship between the dimension Δ and the uniaxial pressure-resistant strength σc of these rock masses, and pictures of the destructive procedure of some rock masses in uniaxial or triaxial tests, etc. Application of the method to engineering design in rock masses showed the potential of its application to engineering practice.

  14. Numerical method to determine mechanical parameters of engineering design in rock masses.

    Science.gov (United States)

    Xue, Ting-He; Xiang, Yi-Qiang; Guo, Fa-Zhong

    2004-07-01

    This paper proposes a new continuity model for engineering in rock masses and a new schematic method for reporting the engineering of rock continuity. This method can be used to evaluate the mechanics of every kind of medium; and is a new way to determine the mechanical parameters used in engineering design in rock masses. In the numerical simulation, the experimental parameters of intact rock were combined with the structural properties of field rock. The experimental results for orthogonally-jointed rock are given. The results included the curves of the stress-strain relationship of some rock masses, the curve of the relationship between the dimension Delta and the uniaxial pressure-resistant strength sc of these rock masses, and pictures of the destructive procedure of some rock masses in uniaxial or triaxial tests, etc. Application of the method to engineering design in rock masses showed the potential of its application to engineering practice.

  15. Dubbel. Handbook for mechanical engineering; 19. completely rev. ed.; Dubbel. Taschenbuch fuer den Maschinenbau

    Energy Technology Data Exchange (ETDEWEB)

    Beitz, W. [Technische Univ. Berlin (Germany); Grote, K.H. [eds.] [Magdeburg Univ. (Germany)

    1997-12-31

    The book is a textbook as well as as a handy source of reference offering a wealth of both fundamental and in-depth information relating to the subject fields of: Mathematics; mechanics; strength of materials; thermodynamics; materials technology; engineering design; mechanical machine components; hydraulic and pneumatic power transmission; electronic components; components of thermal apparatus; energy systems; HVAC engineering; process engineering; machine dynamics; reciprocating engines; automotive technology; fluid flow machines (turbomachinery); manufacturing processes; manufacturing systems; materials handling and conveying; electrical engineering; metrology; automatic control; electronic data processing. (orig./GL) [Deutsch] Nicht nur als Lehrmittel, sondern auch als Nachschlagewerk stellt das Buch das Basis- und Detailwissen der folgenden Gebiete bereit: - Mathematik - Mechanik - Festigkeitslehre - Thermodynamik - Werkstofftechnik - Konstruktionstechnik - mechanische Konstruktionselemente - fluidische Antriebe - elektronische Konstruktionskomponenten - Komponenten des thermischen Apparatebaus - Energietechnik - Klimatechnik - Verfahrenstechnik - Maschinendynamik - Kolbenmaschinen - Stroemungsmaschinen - Kraftfahrzeugtechnik - Fertigungsverfahren - Fertigungsmittel - Foerdertechnik - Elektrotechnik - Messtechnik - Regelungstechnik - elektronische Datenverarbeitung. (orig./GL)

  16. A Protective Mechanism of Visible Red Light in Normal Human Dermal Fibroblasts: Enhancement of GADD45A-Mediated DNA Repair Activity.

    Science.gov (United States)

    Kim, Yeo Jin; Kim, Hyoung-June; Kim, Hye Lim; Kim, Hyo Jeong; Kim, Hyun Soo; Lee, Tae Ryong; Shin, Dong Wook; Seo, Young Rok

    2017-02-01

    The phototherapeutic effects of visible red light on skin have been extensively investigated, but the underlying biological mechanisms remain poorly understood. We aimed to elucidate the protective mechanism of visible red light in terms of DNA repair of UV-induced oxidative damage in normal human dermal fibroblasts. The protective effect of visible red light on UV-induced DNA damage was identified by several assays in both two-dimensional and three-dimensional cell culture systems. With regard to the protective mechanism of visible red light, our data showed alterations in base excision repair mediated by growth arrest and DNA damage inducible, alpha (GADD45A). We also observed an enhancement of the physical activity of GADD45A and apurinic/apyrimidinic endonuclease 1 (APE1) by visible red light. Moreover, UV-induced DNA damages were diminished by visible red light in an APE1-dependent manner. On the basis of the decrease in GADD45A-APE1 interaction in the activating transcription factor-2 (ATF2)-knockdown system, we suggest a role for ATF2 modulation in GADD45A-mediated DNA repair upon visible red light exposure. Thus, the enhancement of GADD45A-mediated base excision repair modulated by ATF2 might be a potential protective mechanism of visible red light. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  17. The International Congress of Mechanical Engineering and Agricultural Sciences - CIIMCA 2013

    Science.gov (United States)

    Remolina-Millán, Aduljay; Hernández-Arroyo, Emil

    2014-06-01

    The organizing committee of The International Congress of Mechanical Engineering and Agricultural Sciences - CIIMCA 2013 - are pleased to present CIIMCA-2013: the first international conference focused on subjects of materials science, mechanical engineering and renewable energy organized by Mechanical Engineering Faculty of the ''Universidad Pontificia Bolivariana'' in Bucaramanga, Colombia. This conference aims to be a place to produce discussions on whole topics of the congress, between the scientists of Colombia and the world. We strongly believe that knowledge is fundamental to the development of our countries. For that reason this multidisciplinary conference is looking forward to integrate engineering, agricultural science and nanoscience and nanotechnology to produce a synergy of this area of knowledge and to achieve scientific and technological developments. Agriculture is a very important topic for our conference; in Colombia, agricultural science needs more attention from the scientific community and the government. In the Faculty of Mechanical Engineering we are beginning to work on these issues to produce knowledge and improve the conditions in our country. The CIIMCA conference is a great opportunity to create interpersonal relationships and networks between scientists around the world. The interaction between scientists is very important in the process of the construction of knowledge. The general chairman encourages and invites you to make friends, relationships and participate strongly in the symposia and all program activities. PhD Aduljay Remolina-Millán Principal Chairman, International Mechanical Engineering and Agricultural Sciences Congress - CIIMCA Msc Emil Hernández-Arroyo Principal Chairman, International Mechanical Engineering and Agricultural Sciences Congress - CIIMCA Conference photograph Conference photograph 'Universidad Pontificia Bolivariana seccional Bucaramanga' host of the first International Mechanical Engineering and

  18. Analysis of engineering cycles thermodynamics and fluid mechanics series

    CERN Document Server

    Haywood, R W

    1980-01-01

    Analysis of Engineering Cycles, Third Edition, deals principally with an analysis of the overall performance, under design conditions, of work-producing power plants and work-absorbing refrigerating and gas-liquefaction plants, most of which are either cyclic or closely related thereto. The book is organized into two parts, dealing first with simple power and refrigerating plants and then moving on to more complex plants. The principal modifications in this Third Edition arise from the updating and expansion of material on nuclear plants and on combined and binary plants. In view of increased

  19. Composite materials. Volume 1: Properties, non-destructive testing, and repair

    Energy Technology Data Exchange (ETDEWEB)

    Schwartz, M.M. [United Technologies Corp., East Hartford, CT (United States)

    1997-12-31

    This book provides a practical overview of the different types, properties, applications and design implementations of the latest composite materials. It describes important composite families, including metals, ceramics, polymers and other engineered materials; shows how each type of composite may be designed, manufactured, strengthened, and repaired; introduces composite modeling techniques; and explains the major industrial applications for composites. Primary markets for this book include materials engineers and designers in aerospace, automotive and transportation industries; works managers, facilities engineers, test engineers, plant engineers, manufacturing and industrial engineers, and production managers; students in material science, mechanical engineering and metallurgy.

  20. Mechanism of repair of acrolein- and malondialdehyde-derived exocyclic guanine adducts by the α-ketoglutarate/Fe(II) dioxygenase AlkB.

    Science.gov (United States)

    Singh, Vipender; Fedeles, Bogdan I; Li, Deyu; Delaney, James C; Kozekov, Ivan D; Kozekova, Albena; Marnett, Lawrence J; Rizzo, Carmelo J; Essigmann, John M

    2014-09-15

    The structurally related exocyclic guanine adducts α-hydroxypropano-dG (α-OH-PdG), γ-hydroxypropano-dG (γ-OH-PdG), and M1dG are formed when DNA is exposed to the reactive aldehydes acrolein and malondialdehyde (MDA). These lesions are believed to form the basis for the observed cytotoxicity and mutagenicity of acrolein and MDA. In an effort to understand the enzymatic pathways and chemical mechanisms that are involved in the repair of acrolein- and MDA-induced DNA damage, we investigated the ability of the DNA repair enzyme AlkB, an α-ketoglutarate/Fe(II) dependent dioxygenase, to process α-OH-PdG, γ-OH-PdG, and M1dG in both single- and double-stranded DNA contexts. By monitoring the repair reactions using quadrupole time-of-flight (Q-TOF) mass spectrometry, it was established that AlkB can oxidatively dealkylate γ-OH-PdG most efficiently, followed by M1dG and α-OH-PdG. The AlkB repair mechanism involved multiple intermediates and complex, overlapping repair pathways. For example, the three exocyclic guanine adducts were shown to be in equilibrium with open-ring aldehydic forms, which were trapped using (pentafluorobenzyl)hydroxylamine (PFBHA) or NaBH4. AlkB repaired the trapped open-ring form of γ-OH-PdG but not the trapped open-ring of α-OH-PdG. Taken together, this study provides a detailed mechanism by which three-carbon bridge exocyclic guanine adducts can be processed by AlkB and suggests an important role for the AlkB family of dioxygenases in protecting against the deleterious biological consequences of acrolein and MDA.

  1. Transcriptomic analysis of tail regeneration in the lizard Anolis carolinensis reveals activation of conserved vertebrate developmental and repair mechanisms.

    Directory of Open Access Journals (Sweden)

    Elizabeth D Hutchins

    Full Text Available Lizards, which are amniote vertebrates like humans, are able to lose and regenerate a functional tail. Understanding the molecular basis of this process would advance regenerative approaches in amniotes, including humans. We have carried out the first transcriptomic analysis of tail regeneration in a lizard, the green anole Anolis carolinensis, which revealed 326 differentially expressed genes activating multiple developmental and repair mechanisms. Specifically, genes involved in wound response, hormonal regulation, musculoskeletal development, and the Wnt and MAPK/FGF pathways were differentially expressed along the regenerating tail axis. Furthermore, we identified 2 microRNA precursor families, 22 unclassified non-coding RNAs, and 3 novel protein-coding genes significantly enriched in the regenerating tail. However, high levels of progenitor/stem cell markers were not observed in any region of the regenerating tail. Furthermore, we observed multiple tissue-type specific clusters of proliferating cells along the regenerating tail, not localized to the tail tip. These findings predict a different mechanism of regeneration in the lizard than the blastema model described in the salamander and the zebrafish, which are anamniote vertebrates. Thus, lizard tail regrowth involves the activation of conserved developmental and wound response pathways, which are potential targets for regenerative medical therapies.

  2. Advanced self-healing asphalt composites in the pavement performance field: mechanisms at the nano level and new repairing methodologies.

    Science.gov (United States)

    Agzenai, Yahya; Pozuelo, Javier; Sanz, Javier; Perez, Ignacio; Baselga, Juan

    2015-01-01

    In an effort to give a global view of this field of research, in this mini-review we highlight the most recent publications and patents focusing on modified asphalt pavements that contain certain reinforcing nanoparticles which impart desirable thermal, electrical and mechanical properties. In response to the increasing cost of asphalt binder and road maintenance, there is a need to look for alternative technologies and new asphalt composites, able to self-repair, for preserving and renewing the existing pavements. First, we will focus on the self-healing property of asphalt, the evidences that support that healing takes place immediately after the contact between the faces of a crack, and how the amount of healing can be measured in both the laboratory and the field. Next we review the hypothetical mechanisms of healing to understand the material behaviour and establish models to quantify the damage-healing process. Thereafter, we outline different technologies, nanotechnologies and methodologies used for self-healing paying particular attention to embedded micro-capsules, new nano-materials like carbon nanotubes and nano-fibres, ionomers, and microwave and induction heating processes.

  3. Transcriptomic analysis of tail regeneration in the lizard Anolis carolinensis reveals activation of conserved vertebrate developmental and repair mechanisms.

    Science.gov (United States)

    Hutchins, Elizabeth D; Markov, Glenn J; Eckalbar, Walter L; George, Rajani M; King, Jesse M; Tokuyama, Minami A; Geiger, Lauren A; Emmert, Nataliya; Ammar, Michael J; Allen, April N; Siniard, Ashley L; Corneveaux, Jason J; Fisher, Rebecca E; Wade, Juli; DeNardo, Dale F; Rawls, J Alan; Huentelman, Matthew J; Wilson-Rawls, Jeanne; Kusumi, Kenro

    2014-01-01

    Lizards, which are amniote vertebrates like humans, are able to lose and regenerate a functional tail. Understanding the molecular basis of this process would advance regenerative approaches in amniotes, including humans. We have carried out the first transcriptomic analysis of tail regeneration in a lizard, the green anole Anolis carolinensis, which revealed 326 differentially expressed genes activating multiple developmental and repair mechanisms. Specifically, genes involved in wound response, hormonal regulation, musculoskeletal development, and the Wnt and MAPK/FGF pathways were differentially expressed along the regenerating tail axis. Furthermore, we identified 2 microRNA precursor families, 22 unclassified non-coding RNAs, and 3 novel protein-coding genes significantly enriched in the regenerating tail. However, high levels of progenitor/stem cell markers were not observed in any region of the regenerating tail. Furthermore, we observed multiple tissue-type specific clusters of proliferating cells along the regenerating tail, not localized to the tail tip. These findings predict a different mechanism of regeneration in the lizard than the blastema model described in the salamander and the zebrafish, which are anamniote vertebrates. Thus, lizard tail regrowth involves the activation of conserved developmental and wound response pathways, which are potential targets for regenerative medical therapies.

  4. Insights into the epigenetic mechanisms involving histone lysine methylation and demethylation in ischemia induced damage and repair has therapeutic implication.

    Science.gov (United States)

    Chakravarty, Sumana; Jhelum, Priya; Bhat, Unis Ahmad; Rajan, Wenson D; Maitra, Swati; Pathak, Salil S; Patel, Anant B; Kumar, Arvind

    2017-01-01

    Cerebral ischemic stroke is one of the leading causes of death and disability worldwide. Therapeutic interventions to minimize ischemia-induced neural damage are limited due to poor understanding of molecular mechanisms mediating complex pathophysiology in stroke. Recently, epigenetic mechanisms mostly histone lysine (K) acetylation and deacetylation have been implicated in ischemic brain damage and have expanded the dimensions of potential therapeutic intervention to the systemic/local administration of histone deacetylase inhibitors. However, the role of other epigenetic mechanisms such as histone lysine methylation and demethylation in stroke-induced damage and subsequent recovery process is elusive. Here, we established an Internal Carotid Artery Occlusion (ICAO) model in CD1 mouse that resulted in mild to moderate level of ischemic damage to the striatum, as suggested by magnetic resonance imaging (MRI), TUNEL and histopathological staining along with an evaluation of neurological deficit score (NDS), grip strength and rotarod performance. The molecular investigations show dysregulation of a number of histone lysine methylases (KMTs) and few of histone lysine demethylases (KDMs) post-ICAO with significant global attenuation in the transcriptionally repressive epigenetic mark H3K9me2 in the striatum. Administration of Dimethyloxalylglycine (DMOG), an inhibitor of KDM4 or JMJD2 class of histone lysine demethylases, significantly ameliorated stroke-induced NDS by restoring perturbed H3K9me2 levels in the ischemia-affected striatum. Overall, these results highlight the novel role of epigenetic regulatory mechanisms controlling the epigenetic mark H3K9me2 in mediating the stroke-induced striatal damage and subsequent repair following mild to moderate cerebral ischemia.

  5. Cellular and molecular mechanisms of repair in acute and chronic wound healing.

    Science.gov (United States)

    Martin, P; Nunan, R

    2015-08-01

    A considerable understanding of the fundamental cellular and molecular mechanisms underpinning healthy acute wound healing has been gleaned from studying various animal models, and we are now unravelling the mechanisms that lead to chronic wounds and pathological healing including fibrosis. A small cut will normally heal in days through tight orchestration of cell migration and appropriate levels of inflammation, innervation and angiogenesis. Major surgeries may take several weeks to heal and leave behind a noticeable scar. At the extreme end, chronic wounds - defined as a barrier defect that has not healed in 3 months - have become a major therapeutic challenge throughout the Western world and will only increase as our populations advance in age, and with the increasing incidence of diabetes, obesity and vascular disorders. Here we describe the clinical problems and how, through better dialogue between basic researchers and clinicians, we may extend our current knowledge to enable the development of novel potential therapeutic treatments.

  6. Mechanical properties of orthodontic wires made of super engineering plastic.

    Science.gov (United States)

    Maekawa, Minami; Kanno, Zuisei; Wada, Takahiro; Hongo, Toshio; Doi, Hisashi; Hanawa, Takao; Ono, Takashi; Uo, Motohiro

    2015-01-01

    Most orthodontic equipment is fabricated from alloys such as stainless steel, Co-Cr and Ni-Ti because of their excellent elastic properties. In recent years, increasing esthetic demands, metal allergy and interference of metals with magnetic resonance imaging have driven the development of non-metallic orthodontic materials. In this study, we assessed the feasibility of using three super engineering plastics (PEEK, PES and PVDF) as orthodontic wires. PES and PVDF demonstrated excellent esthetics, although PEEK showed the highest bending strength and creep resistance. PEEK and PVDF showed quite low water absorption. Because of recent developments in coloration of PEEK, we conclude that PEEK has many advantageous properties that make it a suitable candidate for use as an esthetic metal-free orthodontic wire.

  7. Stirling engine power control and motion conversion mechanism

    Science.gov (United States)

    Marks, David T.

    1983-01-01

    A motion conversion device for converting between the reciprocating motion of the pistons in a Stirling engine and the rotating motion of its output shaft, and for changing the stroke and phase of the pistons, includes a lever pivoted at one end and having a cam follower at the other end. The piston rod engages the lever intermediate its ends and the cam follower engages a cam keyed to the output shaft. The lever pivot can be moved to change the length of the moment arm defined between the cam follower and the piston rod the change the piston stroke and force exerted on the cam, and the levers can be moved in opposite directions to change the phase between pistons.

  8. Mechanical properties of Composite Engineering Structures by Multivolume Micromechanical Modelling

    Directory of Open Access Journals (Sweden)

    B. Novotný

    2000-01-01

    Full Text Available Engineering structures often consist of elements having the character of a periodically repeated composite structure. A multivolume micromechanical model based on a representative cell division into r1 × r2 × r3 subcells with different elastic material properties has been used in this paper to derive macromechanical characteristics of the composite construction response to applied load and temperature changes. The multivolume method is based on ensuring the equilibrium of the considered volume on an average basis. In the same (average way, the continuity conditions of displacements and tractions at the interfaces between subcells and between neighboring representative elements are imposed, resulting in a homogenization procedure that eliminates the discrete nature of the composite model. The details of the method are shown for the case of a concrete block pavement. A parametric study is presented illustrating the influence of joint thickness, joint filling material properties and the quality of bonding between block and filler elements.

  9. Dynamic model of Stirling engine crank mechanism with connected electric generator

    Directory of Open Access Journals (Sweden)

    Vlach R.

    2009-06-01

    Full Text Available This paper treats of a numerical dynamic model of Stirling engine crank mechanism. The model is included in the complex model of combined heat and power unit. The unit is composed of the Stirling engine and of attached three-phase synchronous generator. This generator should start the Stirling engine in motor mode as well. It is necessary to combine the crank shaft dynamic model and the complete thermal model of Stirling engine for simulations and analyses of engine run. Our aim is to create a dynamics model which takes into account the parameters of crankshaft, piston rods, pistons, and attached generator. For unit working, the electro-mechanical behaviour of generator is also important. That is why we experimentally verified the parameters of generator. The measured characteristics are used in a complex model of heat and power unit. Moreover, it is also possible to determine the Stirling engine torque by the help of these electro-mechanical characteristics. These values can be used e. g. for determination of optimal engine working point or for unit control.

  10. A mathematical model of the process of ligament repair: effect of cold therapy and mechanical stress.

    Science.gov (United States)

    Cárdenas Sandoval, Rosy Paola; Garzón-Alvarado, Diego Alexander; Ramírez Martínez, Angélica Maria

    2012-06-07

    This article proposes a mathematical model that predicts the wound healing process of the ligament after a sprain, grade II. The model describes the swelling, expression of the platelet-derived growth factor (PDGF), formation and migration of fibroblasts into the injury area and the expression of collagen fibers. Additionally, the model can predict the effect of ice treatment in reducing inflammation and the action of mechanical stress in the process of remodeling of collagen fibers. The results obtained from computer simulation show a high concordance with the clinical data previously reported by other authors.

  11. Additive Manufacturing of IN100 Superalloy Through Scanning Laser Epitaxy for Turbine Engine Hot-Section Component Repair: Process Development, Modeling, Microstructural Characterization, and Process Control

    Science.gov (United States)

    Acharya, Ranadip; Das, Suman

    2015-09-01

    This article describes additive manufacturing (AM) of IN100, a high gamma-prime nickel-based superalloy, through scanning laser epitaxy (SLE), aimed at the creation of thick deposits onto like-chemistry substrates for enabling repair of turbine engine hot-section components. SLE is a metal powder bed-based laser AM technology developed for nickel-base superalloys with equiaxed, directionally solidified, and single-crystal microstructural morphologies. Here, we combine process modeling, statistical design-of-experiments (DoE), and microstructural characterization to demonstrate fully metallurgically bonded, crack-free and dense deposits exceeding 1000 μm of SLE-processed IN100 powder onto IN100 cast substrates produced in a single pass. A combined thermal-fluid flow-solidification model of the SLE process compliments DoE-based process development. A customized quantitative metallography technique analyzes digital cross-sectional micrographs and extracts various microstructural parameters, enabling process model validation and process parameter optimization. Microindentation measurements show an increase in the hardness by 10 pct in the deposit region compared to the cast substrate due to microstructural refinement. The results illustrate one of the very few successes reported for the crack-free deposition of IN100, a notoriously "non-weldable" hot-section alloy, thus establishing the potential of SLE as an AM method suitable for hot-section component repair and for future new-make components in high gamma-prime containing crack-prone nickel-based superalloys.

  12. Distinct mechanisms for opposite functions of homeoproteins Cdx2 and HoxB7 in double-strand break DNA repair in colon cancer cells.

    Science.gov (United States)

    Soret, Christine; Martin, Elisabeth; Duluc, Isabelle; Dantzer, Françoise; Vanier, Marie; Gross, Isabelle; Freund, Jean-Noël; Domon-Dell, Claire

    2016-05-01

    Homeobox genes, involved in embryonic development and tissues homeostasis in adults, are often deregulated in cancer, but their relevance in pathology is far from being fully elucidated. In colon cancers, we report that the homeoproteins HoxB7 and Cdx2 exhibit different heterogeneous patterns, Cdx2 being localized in moderately altered neoplasic glands in contrast to HoxB7 which predominates in poorly-differentiated areas; they are coexpressed in few cancer cells. In human colon cancer cells, both homeoproteins interact with the DNA repair factor KU70/80, but functional studies reveal opposite effects: HoxB7 stimulates DNA repair and cell survival upon etoposide treatment, whereas Cdx2 inhibits both processes. The stimulatory effect of HoxB7 on DNA repair requires the transactivation domain linked to the homeodomain involved in the interaction with KU70/80, whereas the transactivation domain of Cdx2 is dispensable for its inhibitory function, which instead needs the homeodomain to interact with KU70/80 and the C-terminal domain. Thus, HoxB7 and Cdx2 respectively use transcription-dependent and -independent mechanisms to stimulate and inhibit DNA repair. In addition, in cells co-expressing both homeoproteins, Cdx2 lessens DNA repair activity through a novel mechanism of inhibition of the transcriptional function of HoxB7, whereby Cdx2 forms a molecular complex with HoxB7 and prevents it to recognize its target in the chromatin. These results point out the complex interplay between the DSB DNA repair activity and the homeoproteins HoxB7 and Cdx2 in colon cancer cells, making the balance between these factors a determinant and a potential indicator of the efficacy of genotoxic drugs.

  13. STRATEGIES TO TEACH COSTING AND SUSTAINABLE DESIGN IN TODAY'S MECHANICAL ENGINEERING CURRICULUM

    Directory of Open Access Journals (Sweden)

    KIRALY Andrei

    2015-06-01

    Full Text Available Not a long time ago in “Eastern Economies”, especially in the mechanical design domain, words like costing or sustainability were practical neglected. Their importance is raising nowadays more and more and the author explains how it introduced them in mechanical engineers curriculum at the computer aided design discipline, because good habits must be implemented from young ages.

  14. A Blended Learning Approach to Teach Fluid Mechanics in Engineering

    Science.gov (United States)

    Rahman, Ataur

    2017-01-01

    This paper presents a case study on the teaching and learning of fluid mechanics at the University of Western Sydney (UWS), Australia, by applying a blended learning approach (BLA). In the adopted BLA, various flexible learning materials have been made available to the students such as online recorded lectures, online recorded tutorials, hand…

  15. Review of the Mechanical Engineering Challenges associated with the SNS* Power Ramp Up

    Energy Technology Data Exchange (ETDEWEB)

    Murdoch, Graeme R [ORNL; Holding, Mike [ORNL; Ladd, Peter [ORNL; Potter, Kerry G [ORNL; Roseberry, Jr., R Tom [ORNL

    2008-01-01

    Since commissioning of the SNS in April 2006 the beam power has been steadily increasing towards the design intensity of 1.4 MW. Several areas of the accelerator have been shown to require modifications, upgrades or new designs of mechanical equipment to support the power ramp schedule. This paper presents mechanical engineering design work implemented since initial commissioning along with a review of current projects and discussion of mechanical engineering issues being addressed that are a direct result of design decisions made early in the project.

  16. The fluid mechanics of scleral buckling surgery for the repair of retinal detachment.

    Science.gov (United States)

    Foster, William Joseph; Dowla, Nadia; Joshi, Saurabh Y; Nikolaou, Michael

    2010-01-01

    Scleral buckling is a common surgical technique used to treat retinal detachments that involves suturing a radial or circumferential silicone element on the sclera. Although this procedure has been performed since the 1960s, and there is a reasonable experimental model of retinal detachment, there is still debate as to how this surgery facilitates the re-attachment of the retina. Finite element calculations using the COMSOL Multiphysics system are utilized to explain the influence of the scleral buckle on the flow of sub-retinal fluid in a physical model of retinal detachment. We found that, by coupling fluid mechanics with structural mechanics, laminar fluid flow and the Bernoulli effect are necessary for a physically consistent explanation of retinal reattachment. Improved fluid outflow and retinal reattachment are found with low fluid viscosity and rapid eye movements. A simulation of saccadic eye movements was more effective in removing sub-retinal fluid than slower, reading speed, eye movements in removing subretinal fluid. The results of our simulations allow us to explain the physical principles behind scleral buckling surgery and provide insight that can be utilized clinically. In particular, we find that rapid eye movements facilitate more rapid retinal reattachment. This is contradictory to the conventional wisdom of attempting to minimize eye movements.

  17. [Molecular repair mechanisms using the Intratissue Percutaneous Electrolysis technique in patellar tendonitis].

    Science.gov (United States)

    Abat, F; Valles, S L; Gelber, P E; Polidori, F; Stitik, T P; García-Herreros, S; Monllau, J C; Sanchez-Ibánez, J M

    2014-01-01

    To investigate the molecular mechanisms of tissue response after treatment with the Intratissue Percutaneous Electrolysis (EPI(®)) technique in collagenase-induced tendinopathy in Sprague-Dawley rats. Tendinopathy was induced by injecting 50 μg of type i collagenase into the patellar tendon of 24 Sprague Dawley rats of 7 months of age and weighting 300 g. The sample was divided into 4 groups: the control group, collagenase group, and two EPI(®) technique treatment groups of 3 and 6 mA, respectively. An EPI(®) treatment session was applied, and after 3 days, the tendons were analysed using immunoblotting and electrophoresis techniques. An analysis was also made of cytochrome C protein, Smac/Diablo, vascular endothelial growth factor and its receptor 2, as well as the nuclear transcription factor peroxisome proliferator-activated receptor gamma. A statistically significant increase, compared to the control group, was observed in the expression of cytochrome C, Smac/Diablo, vascular endothelial growth factor, its receptor 2 and peroxisome proliferator-activated receptor gamma in the groups in which the EPI(®) technique was applied. EPI(®) technique produces an increase in anti-inflammatory and angiogenic molecular mechanisms in collagenase-induced tendon injury in rats. Copyright © 2013 SECOT. Published by Elsevier Espana. All rights reserved.

  18. Simulation of Thermal-Mechanical Strength for Marine Engine Piston Using FEA

    Directory of Open Access Journals (Sweden)

    Jiang Guo He

    2014-03-01

    Full Text Available Simulation of Thermal-Mechanical Strength for Marine Engine Piston Using FEA Abstract: This paper involves simulation of a 2-stroke 6S35ME marine diesel engine piston to determine its temperature field, thermal, mechanical and coupled thermal-mechanical stress. The distribution and magnitudes of the afore-mentioned strength parameters are useful in design, failure analysis and optimization of the engine piston. The piston model was developed in solid-works and imported into ANSYS for preprocessing, loading and post processing. Material model chosen was 10-node tetrahedral thermal solid 87. The simulation parameters used in this paper were piston material, combustion pressure, inertial effects and temperature. The highest calculated stress was the thermal-mechanical coupled stress and was below the yield stress of the piston material (580Mpa at elevated temperatures hence the piston would withstand the induced stresses during work cycles.

  19. Grey Repairable System Analysis

    Institute of Scientific and Technical Information of China (English)

    Renkuan Guo; Charles Ernie Love

    2006-01-01

    In this paper, we systematically discuss the basic concepts of grey theory, particularly the grey differential equation and its mathematical foundation, which is essentially unknown in the reliability engineering community. Accordingly,we propose a small-sample based approach to estimate repair improvement effects by partitioning system stopping times into intrinsic functioning times and repair improvement times. An industrial data set is used for illustrative purposes in a stepwise manner.

  20. Development of a novel sodium fusidate-loaded triple polymer hydrogel wound dressing: Mechanical properties and effects on wound repair.

    Science.gov (United States)

    Jin, Sung Giu; Kim, Kyeong Soo; Kim, Dong Wuk; Kim, Dong Shik; Seo, Youn Gee; Go, Toe Gyung; Youn, Yu Seok; Kim, Jong Oh; Yong, Chul Soon; Choi, Han-Gon

    2016-01-30

    To develop a novel sodium fusidate-loaded triple polymer hydrogel dressing (TPHD), numerious polyvinyl alcohol-based (PVA) hydrogel dressings were prepared with various hydrophilic polymers using the freeze-thaw method, and their hydrogel dressing properties were assessed. Among the hydrophilic polymers tested, sodium alginate (SA) improved the swelling capacity the most, and polyvinyl pyrrolidone (PVP) provided the greatest improvement in bioadhesive stength and mechanical properties. Thus, PVA based-TPHDs were prepared using different ratios of PVP:SA. The effect of selected PVP:SA ratios on the swelling capacity, bioadhesive strength, mechanical properties, and drug release, permeation and deposition characteristics of sodium fusidate-loaded PVA-based TPHDs were assessed. As the ratio of PVP:SA increased in PVA-loaded TPHD, the swelling capacity, mechanical properties, drug release, permeation and deposition were improved. The TPHD containing PVA, PVP, SA and sodium fusidate at the weight ratio of 10/6/1/1 showed excellent hydrogel dressing properties, release, permeation and deposition of drug. Within 24h, 71.8 ± 1.3% of drug was released. It permeated 625.1 ± 81.2 μg/cm(2) through the skin and deposited of 313.8 ± 24.1 μg/cm(2) within 24h. The results of in vivo pharmacodynamic studies showed that sodium fusidate-loaded TPHD was more effective in improving the repair process than was a commercial product. Thus, this sodium fusidate-loaded TPHD could be a novel tool in wound care.