Sample records for albilineans ashby dowson

  1. Caracterização molecular e patogênica de isolados de Xanthomonas albilineans (Ashby) Dowson, agente causal da escaldadura das folhas da cana-de-açúcar Molecular and pathogenic characterization of isolates of Xanthomonas albilineans (Ashby) Dowson, causal agent of sugarcane leaf scald


    Mariana de Souza e Silva; Ivan Paulo Bedendo; Marcos Virgílio Casagrande


    A escaldadura das folhas, causada pela bactéria Xanthomonas albilineans (Ashby) Dowson, é uma das cinco doenças mais importantes da cana-de-açúcar e sua ocorrência reduz o rendimento e a longevidade da cultura. Variedades resistentes têm sido usadas para o controle, porém há evidências da ocorrência de variantes do patógeno. Em campos comerciais do Estado de São Paulo, tem sido observado que a mesma variedade de cana se apresenta como resistente em uma região e suscetível em outra, sugerindo ...

  2. Caracterização molecular e patogênica de isolados de Xanthomonas albilineans (Ashby) Dowson, agente causal da escaldadura das folhas da cana-de-açúcar


    Mariana de Souza e Silva; Bedendo,Ivan Paulo; Casagrande,Marcos Virgílio


    A escaldadura das folhas, causada pela bactéria Xanthomonas albilineans (Ashby) Dowson, é uma das cinco doenças mais importantes da cana-de-açúcar e sua ocorrência reduz o rendimento e a longevidade da cultura. Variedades resistentes têm sido usadas para o controle, porém há evidências da ocorrência de variantes do patógeno. Em campos comerciais do Estado de São Paulo, tem sido observado que a mesma variedade de cana se apresenta como resistente em uma região e suscetível em outra, sugerindo ...

  3. Caracterização molecular e patogênica de isolados de Xanthomonas albilineans (Ashby Dowson, agente causal da escaldadura das folhas da cana-de-açúcar Molecular and pathogenic characterization of isolates of Xanthomonas albilineans (Ashby Dowson, causal agent of sugarcane leaf scald

    Directory of Open Access Journals (Sweden)

    Mariana de Souza e Silva


    Full Text Available A escaldadura das folhas, causada pela bactéria Xanthomonas albilineans (Ashby Dowson, é uma das cinco doenças mais importantes da cana-de-açúcar e sua ocorrência reduz o rendimento e a longevidade da cultura. Variedades resistentes têm sido usadas para o controle, porém há evidências da ocorrência de variantes do patógeno. Em campos comerciais do Estado de São Paulo, tem sido observado que a mesma variedade de cana se apresenta como resistente em uma região e suscetível em outra, sugerindo a ocorrência de variantes na população do patógeno. Assim, o objetivo deste trabalho foi investigar a presença de diversidade genética da bactéria em áreas comerciais. Um total de 50 isolados foram obtidos em cultura pura a partir de plantas sintomáticas coletadas em Piracicaba (SP, Jaú (SP, região de Ribeirão Preto (SP e Iturama (MG. Os isolados foram confirmados como pertencentes à espécie X. albilineans por meio de características de colônias, serologia e PCR com 'primers' específicos. Para caracterização da diversidade genética, foi usado o método de Rep-PCR, a partir do DNA extraído de cada isolado. Oito isolados, provenientes dos diferentes grupos identificados por rep-PCR, foram usados em testes de patogenicidade, por meio de inoculação em duas variedades de cana. Os resultados confirmaram todos os isolados como pertencentes à espécie X. albilineans. Por meio de rep-PCR, foi demonstrada diversidade genética entre os isolados, os quais foram separados em três grupos: um grupo composto somente pelos isolados de Piracicaba; um segundo, contendo todos os isolados amostrados em Jaú e na região de Ribeirão Preto, e um isolado de Iturama; e, no terceiro, somente dois isolados coletados em Iturama. Os testes de patogenicidade revelaram diferenças na agressividade entre isolados, porém sem relação com sua região de origem. Este trabalho revelou a ocorrência de diversidade genética e de agressividade dentro da

  4. The Ashby Project Week (United States)

    Tomlinson, M. J.; Daniels, D. J.


    Discusses the offering of a residential project course for students in 1972 and a similar course for teachers in 1973 at the Grammar School, Ashby-de-la-Zouch, Leicestershire. Included are descriptions of participants reactions and course objectives and topics. (CC)

  5. STS-112 Crew Interviews: Ashby (United States)


    STS-112 Mission Commander Jeffrey Ashby is seen during this preflight interview, answering questions about his inspiration in becoming an astronaut and his career path and provides an overview of the mission. Ashby outlines his role in the mission in general, and specifically during the docking and extravehicular activities (EVAs). He describes the payload (S1 truss) and the importance that the S1 truss will have in the development of the International Space Station (ISS). Ashby discusses the delivery and installation of the S1 truss scheduled to be done in the planned EVAs in some detail. He touches on the use and operation of the Canadarm 2 robotic arm in this process and outlines what supplies will be exchanged with the resident crew of the ISS during transfer activities. He ends with his thoughts on the value of the ISS in fostering international cooperation.

  6. Xanthan production by Xanthomonas albilineans infecting sugarcane stalks. (United States)

    Blanch, María; Legaz, María-Estrella; Vicente, Carlos


    Xanthomonas albilineans is the causal organism of leaf scald, a bacterial vascular disease of sugarcane. Xanthomonas may invade the parenchyma between the bundles and cause reddened pockets of gum, identified as a xanthan-like polysaccharide. Since xanthan contains glucuronic acid, the ability of Xanthomonas to produce an active UDP glucose dehydrogenase is often seen as a virulence factor. X. albilineans axenically cultured did not secrete xanthans to Willbrink liquid media, but the use of inoculated sugarcane tissues for producing and characterizing xanthans has been required. A hypothesis about the role of sugarcane polysaccharides to assure the production of bacterial xanthan is discussed.

  7. STS-100 Crew Interview: Jeff Ashby (United States)


    STS-100 Pilot Jeff Ashby is seen being interviewed. He answers questions about his inspiration to become an astronaut and his career path. He gives details on the mission's goals and significance, the rendezvous and docking of Endeavour with the International Space Station (ISS), the mission's spacewalks, and installation and capabilities of the Space Station robotic arm, UHF antenna, and Rafaello Logistics Module. Ashby then discusses his views about space exploration as it becomes an international collaboration.

  8. STS-93 Crew Interview: Jeff Ashby (United States)


    Live footage of a preflight interview with Pilot Jeffrey S. Ashby is presented. The interview addresses many different questions including why Ashby wanted to be an astronaut, how he feels about being the rookie on this launch, and what he expects to feel when he lifts off. Other interesting information that this one-on-one interview discusses is the deployment of the Chandra satellite, why people care about x ray energy, whether or not Chandra will compliment the other X Ray Observatories currently in operation, and his responsibilities during the major events of this mission. The Southwest Research Ultraviolet Imaging System (SWUIS) on board Columbia, and the two observatories presently in orbit (Gamma Ray Observatory, and Hubble Space Telescope) are also discussed.

  9. An experimental evaluation of the Hamrock and Dowson minimum film thickness equation for fully flooded EHD point contacts (United States)

    Koye, K. A.; Winer, W. O.


    Fifty-seven measurements of the minimum lubricant film separating the elastohydrodynamically lubricated point contact of a steel crowned roller and a flat sapphire disk were made by an optical interferometry technique. The data collected were used to evaluate the Hamrock and Dowson minimum EHD film thickness model over a practical range of contact ellipticity ratio where the major axis of the contact ellipse is aligned both parallel and perpendicular to the direction of motion. A statistical analysis of the measured film thickness data showed that on the average the experimental data averaged 30 percent greater film thickness than the Hamrock and Dowson model predicts.

  10. Gluconacetobacter diazotrophicus Elicits a Sugarcane Defense Response Against a Pathogenic Bacteria Xanthomonas albilineans. (United States)

    Arencibia, Ariel D; Vinagre, Fabiano; Estevez, Yandi; Bernal, Aydiloide; Perez, Juana; Cavalcanti, Janaina; Santana, Ignacio; Hemerly, Adriana S


    A new role for the plant growth-promoting nitrogen-fixing endophytic bacteria Gluconacetobacter diazotrophicus has been identified and characterized while it is involved in the sugarcane-Xanthomonas albilineans pathogenic interactions. Living G.diazotrophicus possess and/or produce elicitor molecules which activate the sugarcane defense response resulting in the plant resistance to X. albilineans, in this particular case controlling the pathogen transmission to emerging agamic shoots. A total of 47 differentially expressed transcript derived fragments (TDFs) were identified by cDNA-AFLP. Transcripts showed significant homologies to genes of the ethylene signaling pathway (26%), proteins regulates by auxins (9%), beta-1,3 Glucanase proteins (6%) and ubiquitin genes (4%), all major signaling mechanisms. Results point toward a form of induction of systemic resistance in sugarcane-G. diazotrophicus interactions which protect the plant against X. albilineans attack.

  11. Gluconacetobacter diazotrophicus Elicits a Sugarcane Defense Response Against a Pathogenic Bacteria Xanthomonas albilineans (United States)

    Vinagre, Fabiano; Estevez, Yandi; Bernal, Aydiloide; Perez, Juana; Cavalcanti, Janaina; Santana, Ignacio; Hemerly, Adriana S


    A new role for the plant growth-promoting nitrogen-fixing endophytic bacteria Gluconacetobacter diazotrophicus has been identified and characterized while it is involved in the sugarcane-Xanthomonas albilineans pathogenic interactions. Living G.diazotrophicus possess and/or produce elicitor molecules which activate the sugarcane defense response resulting in the plant resistance to X. albilineans, in this particular case controlling the pathogen transmission to emerging agamic shoots. A total of 47 differentially expressed transcript derived fragments (TDFs) were identified by cDNA-AFLP. Transcripts showed significant homologies to genes of the ethylene signaling pathway (26%), proteins regulates by auxins (9%), β-1,3 Glucanase proteins (6%) and ubiquitin genes (4%), all major signaling mechanisms. Results point toward a form of induction of systemic resistance in sugarcane-G. diazotrophicus interactions which protect the plant against X. albilineans attack. PMID:19516988

  12. Pilot Ashby in the White Room (United States)


    STS-93 Pilot Jeffrey S. Ashby is checked out by white room closeout crew members before entering the orbiter Columbia. The white room is an environmental chamber at the end of the orbiter access arm that provides entry to the orbiter crew compartment. STS-93 is a five-day mission primarily to release the Chandra X- ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. After Space Shuttle Columbia's July 20 and 22 launch attempts were scrubbed, the launch was again rescheduled for Friday, July 23, at 12:24 a.m. EDT. The target landing date is July 27 at 11:20 p.m. EDT.

  13. Genomic insights into strategies used by Xanthomonas albilineans with its reduced artillery to spread within sugarcane xylem vessels

    Directory of Open Access Journals (Sweden)

    Pieretti Isabelle


    Full Text Available Abstract Background Xanthomonas albilineans causes leaf scald, a lethal disease of sugarcane. X. albilineans exhibits distinctive pathogenic mechanisms, ecology and taxonomy compared to other species of Xanthomonas. For example, this species produces a potent DNA gyrase inhibitor called albicidin that is largely responsible for inducing disease symptoms; its habitat is limited to xylem; and the species exhibits large variability. A first manuscript on the complete genome sequence of the highly pathogenic X. albilineans strain GPE PC73 focused exclusively on distinctive genomic features shared with Xylella fastidiosa—another xylem-limited Xanthomonadaceae. The present manuscript on the same genome sequence aims to describe all other pathogenicity-related genomic features of X. albilineans, and to compare, using suppression subtractive hybridization (SSH, genomic features of two strains differing in pathogenicity. Results Comparative genomic analyses showed that most of the known pathogenicity factors from other Xanthomonas species are conserved in X. albilineans, with the notable absence of two major determinants of the “artillery” of other plant pathogenic species of Xanthomonas: the xanthan gum biosynthesis gene cluster, and the type III secretion system Hrp (hypersensitive response and pathogenicity. Genomic features specific to X. albilineans that may contribute to specific adaptation of this pathogen to sugarcane xylem vessels were also revealed. SSH experiments led to the identification of 20 genes common to three highly pathogenic strains but missing in a less pathogenic strain. These 20 genes, which include four ABC transporter genes, a methyl-accepting chemotaxis protein gene and an oxidoreductase gene, could play a key role in pathogenicity. With the exception of hypothetical proteins revealed by our comparative genomic analyses and SSH experiments, no genes potentially involved in any offensive or counter-defensive mechanism

  14. Identification of xanthans isolated from sugarcane juices obtained from scalded plants infected by Xanthomonas albilineans. (United States)

    Fontaniella, Blanca; Rodríguez, C W; Piñón, Dolores; Vicente, C; Legaz, María-Estrella


    The exudate gum produced by Xanthomonas albilineans, a specific sugarcane pathogen, has been isolated from juices of diseased sugarcane stalks, hydrolyzed with hydrochloric acid, and the hydrolysate analyzed by capillary electrophoresis. Sucrose. cellobiose, mannose, glucose, glucose-1-P and glucuronic acid were identified as the major components of the polysaccharide isolated from diseased stalks. Juices from healthy stalks contained maltose instead of cellobiose. The chemical nature of this polysaccharide is discussed.

  15. Occurrence of Xanthomonas campestris pv. campestris (Pammel, 1895 Dowson 1939, on Brassicas in Montenegro

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    Dragana Radunović


    Full Text Available Brassicas form the most important group of vegetable crops in Montenegro. The cabbage(Brassica oleracea var. capitata is most commonly grown, although other brassicas,particularly kale, Brussels sprout, cauliflower and broccoli, have been increasingly producedsince recently. One of the specialties of vegetable production in Montenegro is growing ofcollard (Brassica oleracea var. acephala, which is the simplest variety of the Brassica oleraceaspecies and in the nearest relation with their wild ancestor – the sylvestris variety.Diseases are the main restrictive factors for successful production of these vegetables.Susceptibility of the cultivars and inadequate control often result in more or less damagedcrops in some plots.Causal agents of brassica diseases, especially bacterial, have not been investigated inMontenegro until 2009. Since the symptoms observed in 2009 were „V” shaped leaf edgenecrosis and black rot of vascular tissue, it was assumed that they were caused by plantpathogenic bacterium Xanthomonas campestris pv. campestris.Samples of the infected plants were collected from different localities in Montenegro.Isolation and identification of the bacterium were performed using laboratory methodsaccording to Schaad (1980, Lelliott and Stead (1987 and Arsenijević (1997. Examinationof chosen bacterial isolates was conducted using both, classical bacteriological methods(examination of their pathogenic, morphological, cultivation and biochemical and physiologicalcharacteristics, and ELISA test.The obtained results confirmed the presence of X.campestris pv. campestris (Pammel,1895 Dowson 1939, on cabbage, kale, broccoli and collard in Montenegro. This is the firstexperimental evidence that collard is the host of X. campestris pv. campestris in Montenegro.

  16. STS-112 Commander Ashby during post landing news conference (United States)


    KENNEDY SPACE CENTER, FLA. - STS-112 Commander Jeffrey Ashby is shown during the crew's post-landing briefing for the media. Mission STS-112 was the 15th assembly flight to the International Space Station, installing the S1 truss. The landing was the 60th at KSC in the history of the Shuttle program.

  17. The Making of a Missionary: Eric Ashby and Technology. (United States)

    Silver, Harold


    Examines the work of Eric Ashby, a missionary of the technology age in Great Britain, an analyst of status quo and change proponents of higher education,; and an implementer of technology curricula. He warned in the 1950s that if Western academies did not adapt to/with technology, they would not survive. (KDR)

  18. Antagonism of Gluconacetobacter diazotrophicus (a sugarcane endosymbiont) against Xanthomonas albilineans (pathogen) studied in alginate-immobilized sugarcane stalk tissues. (United States)

    Blanco, Yolanda; Blanch, María; Piñón, Dolores; Legaz, María-Estrella; Vicente, Carlos


    Xanthomonas albilineans, a pathogenic bacterium that produces leaf scald disease of sugarcane, secretes a xanthan-like gum that invades both xylem and phloem of the host. Xanthan production has been verified after experimental infection of stalk segments of healthy plants. Moreover, Gluconacetobacter diazotrophicus is a nitrogen-fixing endosymbiont of sugarcane plants that antagonizes with X. albilineans by impeding the production of the bacterial gum. The physiological basis of this antagonism has been studied using tissues of sugarcane stalks previously inoculated with the endosymbiont, then immobilized in calcium alginate and maintained in a culture medium for Gluconacetobacter. Under these conditions, bacteria infecting immobilized tissues are able to secrete to the medium a lysozyme-like bacteriocin that inhibits the growth of X. albilineans.

  19. STS-93 Pilot Ashby suits up for launch (United States)


    In the Operations and Checkout Building during final launch preparations for the third time, STS-93 Pilot Jeffrey S. Ashby pulls on his glove, part of his launch and entry suit. After Space Shuttle Columbia's July 20 and 22 launch attempts were scrubbed, the launch was again rescheduled for Friday, July 23, at 12:24 a.m. EDT. STS-93 is a five-day mission primarily to release the Chandra X-ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. The STS-93 crew numbers five: Commander Eileen Collins, Ashby, and Mission Specialists Stephen A. Hawley (Ph.D.), Catherine G. Coleman (Ph.D.) and Michel Tognini of France, with the Centre National d'Etudes Spatiales (CNES). Collins is the first woman to serve as commander of a shuttle mission.

  20. STS-93 Pilot Ashby arrives at SLF for launch (United States)


    STS-93 Pilot Jeffrey S. Ashby lands at Kennedy Space Center's Shuttle Landing Facility (SLF) aboard a T-38 jet aircraft. He and other crew members Commander Eileen Collins and Mission Specialists Steven A. Hawley (Ph.D.), Catherine G. 'Cady' Coleman (Ph.D.) and Michel Tognini of France, with the Centre National d'Etudes Spatiales (CNES), are arriving for pre-launch activities. STS-93 is Ashby's inaugural Shuttle flight. The primary mission of STS-93 is the release of the Chandra X-ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. The new telescope is 20 to 50 times more sensitive than any previous X-ray telescope and is expected to unlock the secrets of supernovae, quasars and black holes.

  1. Gluconacetobacter diazotrophicus, a sugar cane endosymbiont, produces a bacteriocin against Xanthomonas albilineans, a sugar cane pathogen. (United States)

    Piñón, Dolores; Casas, Mario; Blanch, María; Fontaniella, Blanca; Blanco, Yolanda; Vicente, Carlos; Solas, María-Teresa; Legaz, María-Estrella


    Gluconacetobacter diazotrophicus in liquid culture secretes proteins into the medium. Both medium containing Gluconacetobacter protein and a solution of this protein after acetone precipitation appeared to inhibit the growth of Xanthomonas albilineans in solid culture. This apparent inhibition of bacterial growth has, in fact, been revealed to be lysis of bacterial cells, as demonstrated by transmission electron microscopy. Fractionation of the Gluconacetobacter protein mixture in size-exclusion chromatography reveals a main fraction with lysozyme-like activity which produces lysis of both living bacteria and isolated cell walls.

  2. Surface polysaccharides and quorum sensing are involved in the attachment and survival of Xanthomonas albilineans on sugarcane leaves. (United States)

    Mensi, Imene; Daugrois, Jean-Heinrich; Pieretti, Isabelle; Gargani, Daniel; Fleites, Laura A; Noell, Julie; Bonnot, Francois; Gabriel, Dean W; Rott, Philippe


    Xanthomonas albilineans, the causal agent of sugarcane leaf scald, is a bacterial plant pathogen that is mainly spread by infected cuttings and contaminated harvesting tools. However, some strains of this pathogen are known to be spread by aerial means and are able to colonize the phyllosphere of sugarcane before entering the host plant and causing disease. The objective of this study was to identify the molecular factors involved in the survival or growth of X. albilineans on sugarcane leaves. We developed a bioassay to test for the attachment of X. albilineans on sugarcane leaves using tissue-cultured plantlets grown in vitro. Six mutants of strain XaFL07-1 affected in surface polysaccharide production completely lost their capacity to survive on the sugarcane leaf surface. These mutants produced more biofilm in vitro and accumulated more cellular poly-β-hydroxybutyrate than the wild-type strain. A mutant affected in the production of small molecules (including potential biosurfactants) synthesized by non-ribosomal peptide synthetases (NRPSs) attached to the sugarcane leaves as well as the wild-type strain. Surprisingly, the attachment of bacteria on sugarcane leaves varied among mutants of the rpf gene cluster involved in bacterial quorum sensing. Therefore, quorum sensing may affect polysaccharide production, or both polysaccharides and quorum sensing may be involved in the survival or growth of X. albilineans on sugarcane leaves.

  3. STS-112 Commander Ashby in white room before launch (United States)


    KENNEDY SPACE CENTER, FLA. - -- In the White Room at Launch Pad 39B, STS-112 Commander Jeffrey Ashby receives assistance with his spacesuit before boarding Space Shuttle Atlantis. Liftoff is schedued for 3:46 p.m. EDT. Along with a crew of six, Atlantis will carry the S1 Integrated Truss Structure and the Crew and Equipment Translation Aid (CETA) Cart A to the International Space Station (ISS). The CETA is the first of two human-powered carts that will ride along the ISS railway, providing mobile work platforms for future spacewalking astronauts. On the 11-day mission, three spacewalks are planned to attach the S1 truss.

  4. STS-100 Pilot Ashby arrives at KSC before launch (United States)


    KENNEDY SPACE CENTER, Fla. - STS-100 Pilot Jeffrey S. Ashby arrives at the KSC Shuttle Landing Facility aboard a T-38 jet aircraft to get ready for launch. The 11-day mission to the International Space Station will deliver and integrate the Spacelab Logistics Pallet/Launch Deployment Assembly, which includes the Space Station Remote Manipulator system and the UHF Antenna, and the Multi-Purpose Logistics Module Raffaello. Liftoff on mission STS-100 is scheduled at 2:41 p.m. EDT April 19.

  5. STS-112 Commander Ashby suits up for launch (United States)


    KENNEDY SPACE CENTER, FLA. -- STS-112 Commander Jeffrey Ashby finishes suiting up for launch. STS-112 is the 15th assembly flight to the International Space Station, carrying the S1 Integrated Truss Structure and the Crew and Equipment Translation Aid (CETA) Cart A. The CETA is the first of two human-powered carts that will ride along the ISS railway, providing mobile work platforms for future spacewalking astronauts. On the 11-day mission, three spacewalks are planned to attach the S1 truss to the Station. Launch is scheduled for 3:46 p.m. EDT from Launch Pad 39B.

  6. Results from a new Cocks-Ashby style porosity model (United States)

    Barton, Nathan


    A new porosity evolution model is described, along with preliminary results. The formulation makes use of a Cocks-Ashby style treatment of porosity kinetics that includes rate dependent flow in the mechanics of porosity growth. The porosity model is implemented in a framework that allows for a variety of strength models to be used for the matrix material, including ones with significant changes in rate sensitivity as a function of strain rate. Results of the effect of changing strain rate sensitivity on porosity evolution are shown. The overall constitutive model update involves the coupled solution of a system of nonlinear equations.

  7. STS-93 Pilot Ashby suits up before launch (United States)


    In the Operations and Checkout Building during final launch preparations for the second time, STS-93 Pilot Jeffrey S. Ashby waves after donning his launch and entry suit while a suit tech adjusts his boot. After Space Shuttle Columbia's July 20 launch attempt was scrubbed at the T-7 second mark in the countdown, the launch was rescheduled for Thursday, July 22, at 12:28 a.m. EDT. The target landing date is July 26, 1999, at 11:24 p.m. EDT. STS- 93 is a five-day mission primarily to release the Chandra X-ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. The new telescope is 20 to 50 times more sensitive than any previous X-ray telescope and is expected unlock the secrets of supernovae, quasars and black holes. The STS-93 crew numbers five: Commander Eileen M. Collins, Ashby, and Mission Specialists Stephen A. Hawley (Ph.D.), Catherine G. Coleman (Ph.D.) and Michel Tognini of France, with the Centre National d'Etudes Spatiales (CNES). Collins is the first woman to serve as commander of a shuttle mission.

  8. Purification and properties of an unusual UDP-glucose dehydrogenase, NADPH-dependent, from Xanthomonas albilineans. (United States)

    Blanch, María; Legaz, María-Estrella; Vicente, C


    Xanthomonas albilineans produces a UDP-glucose dehydrogenase growing on sucrose. The enzyme oxidizes UDP-glucose to UDP-glucuronic acid by using molecular oxygen and NADPH. Kinetics of enzymatic oxydation of NADPH is linearly dependent on the amount of oxygen supplied. The enzyme has been purified at homogeneity. The value of pI of the purified enzyme is 8.98 and its molecular mass has been estimated as about 14 kDa. The enzyme shows a michaelian kinetics for UDP-glucose concentrations. The value of K(m) for UDP-glucose is 0.87 mM and 0.26 mM for NADPH, although the enzyme has three different sites to interact with NADPH. The enzyme is inhibited by UDP-glucose concentrations higher than 1.3 mM. N-Terminal sequence has been determined as IQPYNH.

  9. Genomic and evolutionary features of the SPI-1 type III secretion system that is present in Xanthomonas albilineans but is not essential for xylem colonization and symptom development of sugarcane leaf scald. (United States)

    Marguerettaz, Mélanie; Pieretti, Isabelle; Gayral, Philippe; Puig, Jérôme; Brin, Chrystelle; Cociancich, Stéphane; Poussier, Stéphane; Rott, Philippe; Royer, Monique


    Xanthomonas albilineans is the causal agent of sugarcane leaf scald. Interestingly, this bacterium, which is not known to be insect or animal associated, possesses a type III secretion system (T3SS) belonging to the injectisome family Salmonella pathogenicity island 1 (SPI-1). The T3SS SPI-1 of X. albilineans shares only low similarity with other available T3SS SPI-1 sequences. Screening of a collection of 128 plant-pathogenic bacteria revealed that this T3SS SPI-1 is present in only two species of Xanthomonas: X. albilineans and X. axonopodis pv. phaseoli. Inoculation of sugarcane with knockout mutants showed that this system is not required by X. albilineans to spread within xylem vessels and to cause disease symptoms. This result was confirmed by the absence of this T3SS SPI-1 in an X. albilineans strain isolated from diseased sugarcane. To investigate the importance of the T3SS SPI-1 during the life cycle of X. albilineans, we analyzed T3SS SPI-1 sequences from 11 strains spanning the genetic diversity of this species. No nonsense mutations or frameshifting indels were observed in any of these strains, suggesting that the T3SS SPI-1 system is maintained within the species X. albilineans. Evolutionary features of T3SS SPI-1 based on phylogenetic, recombination, and selection analyses are discussed in the context of the possible functional importance of T3SS SPI-1 in the ecology of X. albilineans.

  10. Mission Specialist Coleman and Pilot Ashby in the White Room (United States)


    STS-93 Mission Specialist Catherine G. Coleman (Ph.D.) (left) and Pilot Jeffrey S. Ashby (right) are checked out by white room closeout crew members before entering the orbiter Columbia. The white room is an environmental chamber at the end of the orbiter access arm that provides entry to the orbiter crew compartment. STS-93 is a five-day mission primarily to release the Chandra X- ray Observatory, which will allow scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. After Space Shuttle Columbia's July 20 and 22 launch attempts were scrubbed, the launch was again rescheduled for Friday, July 23, at 12:24 a.m. EDT. The target landing date is July 27 at 11:20 p.m. EDT.

  11. STS-93 Pilot Ashby signs autographs after mission presentation (United States)


    STS-93 Pilot Jeffrey S. Ashby signs autographs after a mission presentation for KSC employees. The five-day mission primarily released the Chandra X-ray Observatory, allowing scientists from around the world to study some of the most distant, powerful and dynamic objects in the universe. Chandra is expected to provide unique and crucial information on the nature of objects ranging from comets in our solar system to quasars at the edge of the observable universe. Since X-rays are absorbed by the Earth's atmosphere, space-based observatories are necessary to study these phenomena and allow scientists to analyze some of the greatest mysteries of the universe. STS-93 was also the first mission to have a woman, Eileen M. Collins, serving as Shuttle commander.

  12. STS-100 Pilot Ashby suits up for launch (United States)


    KENNEDY SPACE CENTER, Fla. - STS-100 Pilot Jeffrey S. Ashby gives a silent greeting to his wife, Paige, during suitup for launch in the Operations and Checkout Building. The 11-day mission to the International Space Station will deliver and integrate the Spacelab Logistics Pallet/Launch Deployment Assembly, which includes the Space Station Remote Manipulator system and the UHF Antenna. The mission includes two planned spacewalks for installation of the SSRMS, which will be performed by Mission Specialists Scott E. Parazynski and Chris A. Hadfield. The mission is also the inaugural flight of Multi-Purpose Logistics Module Raffaello, carrying resupply stowage racks and resupply/return stowage platforms. Liftoff on mission STS-100 is scheduled at 2:41 p.m. EDT April 19.

  13. Antimicrobial activity against Xanthomonas albilineans and fermentation kinetics of a lactic acid bacterium isolated from the sugar cane crop

    Directory of Open Access Journals (Sweden)

    Liliana Serna-Cock


    Full Text Available Xanthomonas albilineans is a pathogen that causes leaf scald disease in sugarcane (Saccharum officinarum L. This disease causes the death of seedlings and consequently results in economic losses for sugarcane growers. The objective of this work was to isolate a lactic acid bacterium with antimicrobial activity against X. albilineans from sugarcane crops and to evaluate its antimicrobial activity and its lactic acid production kinetics, biomass yield, and substrate consumption in three different fermentation substrates. To isolate the lactic acid bacterium, samples were collected from different parts of infected and non-infected sugarcane plants of var. CC85-92. Lactococcus lactis ssp. lactis was isolated from the leaves of healthy crops, and showed in vitro antimicrobial activity against the pathogen. Batch fermentations of this isolate (at 32 °C, agitation of 100 rpm, and pH 6 were performed using a commercial substrate (MRS, a commercial substrate supplemented with glucose (MRSG, and a substrate produced from agricultural crop residues (ACR. The highest antimicrobial activity was 5.83 mm in the ACR substrate after 6 h of fermentation. The maximum biomass production of 3.37 g L-1 and the maximum lactic acid production of 12.1 g L-1 were obtained in the MRSG substrate. The lactic acid production did not show any significant differences between the substrates. This lactic acid bacterium showed antimicrobial activity against X. albilineans and is thus a biological alternative for the control of leaf scald disease in sugarcane.

  14. STS-93 Pilot Ashby takes part in emergency egress training (United States)


    STS-93 Pilot Jeffrey S. Ashby pauses for the photographer before climbing into an M-113 armored personnel carrier at the launch pad to take part in emergency egress training. In preparation for their mission, the STS-93 crew are participating in Terminal Countdown Demonstration Test activities that also include a launch-day dress rehearsal culminating with a simulated main engine cut-off. Others in the crew are Commander Eileen M. Collins and Mission Specialists Steven A. Hawley (Ph.D.), Catherine G. Coleman (Ph.D.), and Michel Tognini of France, who represents the Centre National d'Etudes Spatiales (CNES). Collins is the first woman to serve as a mission commander. The primary mission of STS-93 is the release of the Chandra X-ray Observatory, which will allow scientists from around the world to obtain unprecedented X-ray images of exotic environments in space to help understand the structure and evolution of the universe. Chandra is expected to provide unique and crucial information on the nature of objects ranging from comets in our solar system to quasars at the edge of the observable universe. Since X-rays are absorbed by the Earth's atmosphere, space-based observatories are necessary to study these phenomena and allow scientists to analyze some of the greatest mysteries of the universe. The targeted launch date for STS-93 is no earlier than July 20 at 12:36 a.m. EDT from Launch Pad 39B.

  15. STS-100 Pilot Ashby arrives at KSC for TCDT activities (United States)


    KENNEDY SPACE CENTER, Fla. - STS-100 Pilot Jeffrey S. Ashby arrives at KSC for Terminal Countdown Demonstration Test activities. He and the rest of the crew Commander Kent V. Rominger and Mission Specialists Chris Hadfield, Scott E. Parazynski, John L. Phillips, Umberto Guidoni and Yuri Lonchakov -- are going to be taking part in emergency escape training at the pad, equipment familiarization and a simulated launch countdown. An international crew, Hadfield is with the Canadian Space Agency, Guidoni the European Space Agency and Lonchakov the Russian Aviation and Space Agency. The mission is carrying the Multi-Purpose Logistics Module Raffaello and the Canadian robotic arm, SSRMS, to the International Space Station. Raffaello carries six system racks and two storage racks for the U.S. Lab. The SSRMS is crucial to the continued assembly of the orbiting complex and has a unique ability to switch ends as it works, '''inchworming''' along the Station'''s exterior. Launch of mission STS-100 is scheduled for April 19 at 2:41 p.m. EDT from Launch Pad 39A.

  16. Materials selection for low temperature processed high Q resonators using ashby approach

    NARCIS (Netherlands)

    Kazmi, S.N.R.; Salm, Cora; Schmitz, J.


    MicroElectroMechanical Systems (MEMS) is an emerging class of microfabrication technology that can truly be anticipated as an enabling technology for future radio frequency (RF) communications. This work focuses on the material selection using the Ashby approach for the high-Q resonators that need t

  17. Modeling Valuations from Experience: A Comment on Ashby and Rakow (2014) (United States)

    Wulff, Dirk U.; Pachur, Thorsten


    What are the cognitive mechanisms underlying subjective valuations formed on the basis of sequential experiences of an option's possible outcomes? Ashby and Rakow (2014) have proposed a sliding window model (SWIM), according to which people's valuations represent the average of a limited sample of recent experiences (the size of which is estimated…

  18. [Occurrence of Aleurocanthus woglumi Ashby (Hemiptera: Aleyrodidae) in the state of Maranhão, Brazil]. (United States)

    de Lemos, Raimunda N S; da Silva, Gilson S; Araújo, José R G; Das Chagas, Evandro F; Moreira, Aldenise A; Soares, Ana T M


    Aleurocanthus woglumi Ashby in citrus and mango crops in the state of Maranhão, Brazil, is recorded. Samples of 2003 and 2004 from several counties were identified and deposited in the Insect Collection of the Laboratório de Entomologia of the Núcleo de Biotecnologia Agronômica, Universidade Estadual do Maranhão.

  19. Genes diferencialmente expressos em cana-de-açúcar inoculada com Xanthomonas albilineans, o agente causal da escaldadura da folha Diferential gene expression in sugar cane infected with Xanthomonas albilineans, causal agent of leaf scald

    Directory of Open Access Journals (Sweden)

    Karina Maia Dabbas


    Full Text Available A escaldadura da folha, causada pela bactéria Xanthomonas albilineans colonizadora do xilema, é uma das principais doenças da cana-de-açúcar. A sintomatologia na fase crônica é caracterizada principalmente pelo aparecimento de uma faixa branca paralela à nervura central da folha, que evolui até queimar totalmente, sendo também observado brotação de gemas laterais no colmo. Neste trabalho, a técnica de macroarranjos de cDNA foi empregada para o estudo da expressão de 3.575 ESTs (espressed sequence tags em folhas de cana-de-açúcar. Foram utilizadas duas variedades, uma resistente (SP82-1176 e outra suscetível (SP78-4467 a Xanthomonas albilineans as quais foram infectadas mecanicamente por ferimentos. As membranas dos macroarranjos foram confeccionadas a partir de ESTs de bibliotecas de folha e cartucho de cana-de-açúcar provenientes do projeto SUCEST e hibridizadas contra sondas de cDNA de plantas infectadas e controle marcadas com isótopos radioativos. Analisando os resultados dos macroarranjos foi possível verificar um comportamento diferenciado para cada variedade durante o ataque do patógeno. Após realizadas análises estatísticas identificamos na variedade resistente ESTs com expressão induzida relacionadas com biossíntese de isoprenoides, proteínas LRR transmembrânica, "ziper" de leucina, lignificação, tolerância ao frio, diferenciação de plastídeos, sistemas de defesa e de adaptação da planta ao meio ambiente. As ESTs reprimidas na variedade resistente foram àquelas relacionadas com genes responsáveis pela síntese de proteínas do controle da expansão da parede celular, detoxificação e transporte de auxina. Na variedade susceptível foram reprimidas ESTs relacionadas a genes de proteínas das respostas de defesa da planta, biossíntese de Etileno e regulação da transcrição.The leaf scald disease, caused by the xylem-invading pathogen Xanthomonas albilineans, is one of the most devastating



    Manuel Huerta Lara; Elizabeth Cárdenas-Soriano; Reyna Isabel Rojas-Martínez; Jesús Francisco López-Olguín; Delfino Reyes-López; Juliana Bautista-Calles; Omar Romero-Arenas


    La evaluación de resistencia de caña de azúcar (Saccharum officinarum L.) a escaldadura de la hoja ha sido realizada sin consideración del porcentaje de daño al sistema vascular. En el presente estudio se analizó la oclusión de haces vasculares del tallo, en la parte basal y apical de la caña de azúcar, para evaluar resistencia a Xanthomonas albilineans (Xa). Se utilizó caña de azúcar de la variedad susceptible Mex 64-1487 y la resistente Co 997, distribuidas en un diseño de bloques al azar c...

  1. Actividad antimicrobiana y cinética de fermentación de Weissella confusa contra Xanthomonas albilineans

    Directory of Open Access Journals (Sweden)

    Liliana Serna-Cock


    Full Text Available Se evaluó la actividad antimicrobiana de Weissella confusa, una bacteria ácido láctica, contra Xanthomonas albilineans, microrganismo productor de la escaldadura de la hoja en la caña de azúcar. Se midió la cinética de fermentación de la bacteria ácido láctica en sustrato comercial (MRS y en residuos agrícolas de cosecha de caña de azúcar (RAC provenientes de semilleros con 7 meses de edad. Se realizaron fermentaciones sumergidas a 32 °C, cada hora hasta 4 horas, a pH 6 y 100 r.p.m. de agitación. Cada hora se midieron la producción de biomasa, el consumo de sustrato y actividad antimicrobiana. Weissella confusa presentó actividad antimicrobiana contra la bacteria fitopatógena X. albilineans en ambos sustratos, los halos de inhibición presentaron diámetros de 18.94 y 16.77 mm, respectivamente. Weissella confusa, aunque no fue aislada de caña de azúcar, mostró excelente crecimiento en el sustrato RAC comparado con el sustrato comercial MRS; por tanto, puede ser un posible biocontrolador para la escaldadura de la hoja de caña de azúcar, no obstante, se deben evaluar sus mecanismos de acción e impactos biológico y económico en la producción de biomasa ácido láctica.

  2. 高速重载工况Hamrock-Dowson膜厚公式的适用性研究%Study on the Suitability for the Hamrock-Dowson Formula Under Heavy Load and High Speed Working Conditions

    Institute of Scientific and Technical Information of China (English)

    孙浩洋; 张艳平; 管殿柱; 张培国


    采用新型润滑油在高速重载工况下研究Hamrock-Dowson膜厚公式的适用性.研究结果表明,在高速重载工况下,Hamrock-Dowson膜厚公式会带来较大误差,数值解得到的膜厚可达Hamrock-Dowson膜厚公式的2~4倍.所以随着弹流理论的发展和计算技术的飞速进步,润滑设计应不再过多的依赖于各种经验公式,可通过计算软件数值仿真和试验研究来实现.%Using new lubrication oil, the suitability for the Hamrock-Dowson formula under heavy load and high speed working conditions were discussed. It was concluded that Hamrock-Dowson formula was not suitable under heavy load and high speed working conditions, and the numerical results may vary from two to four times than that of Hamrock-Dowson formula results. With the developments of EHL theory and computing technique, the lubricating design should rely on computing software and experimental technique rather than experimental formula.

  3. Molecular dynamics simulation of Ashby-Verrall superplasticity model for nano-crystal%纳米多晶体Ashby-Verrall超塑性模型的分子动力学模拟

    Institute of Scientific and Technical Information of China (English)

    王为; 王长文; 张凯锋



  4. Sugarcane glycoproteins may act as signals for the production of xanthan in the plant-associated bacterium Xanthomonas albilineans. (United States)

    Legaz, María-Estrella; Blanch, María; Piñón, Dolores; Santiago, Rocío; Fontaniella, Blanca; Blanco, Yolanda; Solas, María-Teresa; Vicente, Carlos


    Visual symptoms of leaf scald necrosis in sugarcane (Saccharum officinarum) leaves develop in parallel to the accumulation of a fibrous material invading exocellular spaces and both xylem and phloem. These fibers are produced and secreted by the plant-associated bacterium Xanthomonas albilineans. Electron microscopy and specific staining methods for polysaccharides reveal the polysaccharidic nature of this material. These polysaccharides are not present in healthy leaves or in those from diseased plants without visual symptoms of leaf scald. Bacteria in several leaf tissues have been detected by immunogold labelling. The bacterial polysaccharide is not produced in axenic culture but it is actively synthesized when the microbes invade the host plant. This finding may be due to the production of plant glycoproteins after bacteria infection, which inhibit microbial proteases. In summary, our data are consistent with the existence of a positive feedback loop in which plant-produced glycoproteins act as a cell-to-bacteria signal that promotes xanthan production, by protecting some enzymes of xanthan biosynthesis against from bacterial proteolytic degradation. 

  5. Gamma irradiation as a quarantine treatment against eggs of Citrus black fly (Aleurocanthus woglumi Ashby)

    Energy Technology Data Exchange (ETDEWEB)

    Villavicencio, Anna Lucia C.H.; Araujo, Michel M.; Fanaro, Gustavo B.; Costa, Helbert H.S.F.; Silva, Priscila P.V. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)], e-mail:; Arthur, Valter [Centro de Energia Nuclear na Agricultura (CENA/USP), Piracicaba, SP (Brazil). Lab. de Radibiologia e Ambiente], e-mail:; Faria, Jose Tadeu [Ministerio da Agricultura Pecuaria e Abastecimento (MAPA), Sao Paulo, SP (Brazil)], e-mail:


    The citrus black fruit fly (Aleurocanthus woglumi Ashby) is an important pest of citrus originated in Southeast Asia and its first record in the new world was in Jamaica in 1913. In Brazil, it was detected in 2001 in the state of Para and more recently it was detected in Sao Paulo in 2008. This pest that attacks over 300 species of plants, but its main host are citrus. It is an A2 quarantine pest, because it is not spread throughout the country. The objective of this study was to test doses of 0 (control), 25, 50, 75, 100, 125, 150, 175 and 200 Gy of gamma irradiation for disinfection of eggs of the citrus black fruit fly in leaves of citrus plants. Treatment consisted of 5 replicates with 60 eggs each. Evaluations were performed in the following periods: 1, 3, 5, 7 and 10 days after irradiation. Under the conditions assayed, it could be concluded that a dose of 200 Gy caused 100% mortality of Aleurocanthus woglumi Ashby eggs and could be recommended as a successful quarantine processing against infested plants. (author)

  6. Xanthomonas albilineans OmpA1 appears to be functionally modular and both the OMC and C-like domains are necessary for leaf scald disease of sugarcane. (United States)

    Fleites, Laura A; Mensi, Imène; Gargani, Daniel; Zhang, Shujian; Rott, Philippe; Gabriel, Dean W


    Several EZ-Tn5 insertions in gene locus XALc_0557 (OmpA1) of the sugarcane leaf scald pathogen Xanthomonas albilineans XaFL07-1 were previously found to strongly affect pathogenicity and endophytic stalk colonization. XALc_0557 has a predicted OmpA N-terminal outer membrane channel (OMC) domain and an OmpA C-like domain. Further analysis of mutant M468, with an EZ-Tn5 insertion in the upstream OMC domain coding region, revealed impaired epiphytic and endophytic leaf survival, impaired resistance to sodium dodecyl sulfate (SDS), structural defects in the outer membrane (OM), and hyperproduction of OM vesicles. Cloned full-length XALc_0557 complemented M468 for all phenotypes tested, including pathogenicity, resistance to SDS, and ability to survive both endophytically and epiphytically. Another construct, pCT47.3, which expressed only the C-like domain of XALc_0557, restored resistance to SDS in M468 but failed to complement any other mutant phenotype, indicating that the C-like domain functioned independently of the OMC domain to help maintain OM integrity. pCT47.3 also complemented pathogenicity, resistance to SDS, and stalk colonization in mutant M1152, which carries an EZ-Tn5 insert in the C-like coding region, indicating that both predicted domains are modular and necessary but neither is sufficient for X. albilineans pathogenicity, endophytic survival in, and epiphytic survival on sugarcane.

  7. Numerical simulation on forced convection heat transfer in porous media using Gibson-Ashby constitutive model (United States)

    Wang, J. X.; Jia, P. Y.; Wang, Y. S.; Jiang, L.


    In this article, using Gibson-Ashby constitutive model, we suggest a new method for numerical investigation of forced convection heat transfer in porous foam metal, and try to consolidate the study for mechanical property and that for thermal characteristic. By available experimental data, we simulated to two cases, namely as the transfer in porous media for diameter is 0.6 mm and porosity is 0.402, and for diameter is 1.6 mm and porosity is 0.462. The result, from our constitutive model for single forced convection heat transfer, corresponds well with the experimental data. As for pressure drop prediction in porous is in good agreement with experiment, and the error is only 5% to 10%, but for transfer is less accurate, the error is about 20%, which is acceptable in practice. So it is done that constitutive model is used to simulate the transfer property.

  8. First record of occurrence of mosca-negra-dos-citrus, Aleurocanthus woglumi Ashby, 1915 (Hemiptera: Sternorrhyncha: Aleyrodidae) in Roraima, Brazil = Primeiro registro da ocorrência de mosca-negra-dos-citros, Aleurocanthus woglumi Ashby, 1915 (Hemiptera: Aleyrodidae) em Roraima


    Francisco Clemilto da Silva Maciel; Marcos Wanderley da Silva; Anderson Gonçalves da Silva; Ruy Guilherme Correia; Paulo Roberto Silva Farias; Antonio Cesar Silva Lima


    The Aleurocanthus woglumi Ashby (Hemiptera: Aleyrodidae) is an important pest of citrus. Originated in Asia, this pest was detected in Brazil for the first time in the State of Para, Brazil in 2001. In the culture of citrus fruits the black fly carries direct and indirect damage, impeding the development and production of plants. In addition to restricting trade in local areas from its occurrence to the presence of the plague, since the A. woglumi quarantine pest is considered present (A2) of...

  9. STS-93 Pilot Ashby takes part in suit check in the O&C Bldg. (United States)


    STS-93 Pilot Jeffrey S. Ashby has his launch and entry suit checked by a technician in the Operations and Checkout Bldg. In preparation for their mission, the STS-93 crew are participating in Terminal Countdown Demonstration Test activities that also include equipment check and a launch-day dress rehearsal culminating with a simulated main engine cut-off. Others in the crew participating are Commander Eileen M. Collins and Mission Specialists Steven A. Hawley (Ph.D.), Catherine G. Coleman (Ph.D.) and Michel Tognini of France, who represents the Centre National d'Etudes Spatiales (CNES). Collins is the first woman to serve as a Shuttle commander. The primary mission of STS-93 is the release of the Chandra X-ray Observatory, which will allow scientists from around the world to obtain unprecedented X-ray images of exotic environments in space to help understand the structure and evolution of the universe. The targeted launch date for STS-93 is no earlier than July 20 at 12:36 a.m. EDT from Launch Pad 39B.

  10. VizieR Online Data Catalog: Spitzer-CANDELS catalog within 5 deep fields (Ashby+, 2015) (United States)

    Ashby, M. L. N.; Willner, S. P.; Fazio, G. G.; Dunlop, J. S.; Egami, E.; Faber, S. M.; Ferguson, H. C.; Grogin, N. A.; Hora, J. L.; Huang, J.-S.; Koekemoer, A. M.; Labbe, I.; Wang, Z.


    We chose to locate S-CANDELS inside the wider and shallower fields already covered by Spitzer Extended Deep Survey (SEDS), in regions that enjoy deep optical and NIR imaging from HST/CANDELS. These S-CANDELS fields are thus the Extended GOODS-south (aka the GEMS field, hereafter ECDFS; Rix et al. 2004ApJS..152..163R; Castellano et al. 2010A&A...511A..20C), the Extended GOODS-north (HDFN; Giavalisco et al. 2004, II/261; Wang et al. 2010, J/ApJS/187/251; Hathi et al. 2012ApJ...757...43H; Lin et al. 2012ApJ...756...71L), the UKIDSS UDS (aka the Subaru/XMM Deep Field, Ouchi et al. 2001ApJ...558L..83O; Lawrence et al. 2007, II/319), a narrow field within the EGS (Davis et al. 2007ApJ...660L...1D; Bielby et al. 2012A&A...545A..23B), and a strip within the UltraVista deep survey of the larger COSMOS field (Scoville et al. 2007ApJS..172...38S; McCracken et al. 2012, J/A+A/544/A156). The S-CANDELS observing strategy was designed to maximize the area covered to full depth within the CANDELS area. Each field was visited twice with six months separating the two visits. Table 1 lists the epochs for each field. All of the IRAC full-depth coverage is within the SEDS area (Ashby et al. 2013, J/ApJ/769/80), and almost all is within the area covered by HST for CANDELS. (6 data files).

  11. First Report of Citrus Aleurocanthus woglumi Ashby (Hemiptera: Aleyrodidae in the State of Paraná, Brazil

    Directory of Open Access Journals (Sweden)

    Rúbia de Oliveira Molina


    Full Text Available The citrus blackfly Aleroucanthus woglumi Ashby, (Hemiptera Aleyrodidae is an important pest that occurs in citrus groves, native to south-east Asia. In Brazil, according to the Ministry of Agriculture, this is a quarantine pest (A2 under official control IN 52, 2007 (MAPA and is not widespread in the country. The insect can infest more than 300 host plants, including cultivated plants, ornamentals and weeds, but mostly occurs in the plants of the genus citrus. This paper is the first report of citrus blackfly in the State of Paraná.

  12. Use of first ratoon as categorized seed of sugarcane

    Directory of Open Access Journals (Sweden)

    Héctor Jorge Suárez


    Full Text Available The results obtained on commercial seedbeds of Factory Ofelina (Panamá are presented. Were you sampled 289.55 ha in 13 fields planted with ten varieties in plant cane, ratoon and second shoot those who underwent first molecular diagnosis (PCR for stunting diseases shoot and leaf scald, then staining was performed vascular xylem vessels with safranin whose purpose was to determine the percentage of functional vessels. The molecular diagnosis offered the 49 and 6 % of the samples had the presence of bacteria Leifsonia xyli (subsp xyli and Xanthomonas albilineans (Ashby Dowson respectively, while 92.7 % of the area evaluat- ed showed values ​​ higher than 85 % functionality xylem vessels. In Cuba the total cost of production of regis- tered seed II hovers around $ 8 188 724.2, using the 20 % of ratoon in the country would save approximately $ 1 066 370.7. The use of ratoon as seed is a common practice in countries like Brazil, Colombia, Argentina and Costa Rica, among others, its use is depending on the effectiveness of treatments to be given to the seed through the chain seed and varieties resistance to use.

  13. Biology of the citrus blackfly, Aleurocanthus woglumi Ashby (Hemiptera: Aleyrodidae), in three host plants; Biologia da mosca-negra-dos-citros, Aleurocanthus woglumi Ashby (Hemiptera: Aleyrodidae), em tres plantas hospedeiras

    Energy Technology Data Exchange (ETDEWEB)

    Pena, Marcia R.; Silva, Neliton M. da [Universidade Federal do Amazonas (UFAM), Manaus, AM (Brazil).Lab. de Entomologia Agricola], e-mail:, e-mail:; Venframim, Jose D.; Haddad, Marineia de L. [Escola Superior de Agricultura Luiz de Queiroz (ESALQ/USP), Piracicaba, SP (Brazil). Lab. de Resistencia de Plantas e Plantas Inseticidas], e-mail:, e-mail:; Lourencao, Andre L. [Instituto Agronomico de Campinas (IAC), SP (Brazil)], e-mail:


    The citrus blackfly, Aleurocanthus woglumi Ashby, was detected in Brazil in 2001. The aim of this research was to evaluate the biology, biometry and host preference of A. woglumi in sweet orange, acid lime Tahiti and mango. Experiments were set in laboratory conditions with insects collected in rangpur lime plants in Manaus, State of Amazonas, from January to June of 2006. The following parameters were evaluated: number of spirals (ovo positions) and eggs per plant, number of eggs by spiral per plant, survival of the immature (eggs, 1st, 2nd, 3rd and 4th instars), and length and survival of the immature stage. The mean embrionary period was 15 days for the three hosts. The 4th nymph (puparium) was the longest during nymph development. Second and third instars had the highest survival. The mean length of the egg-adult cycle was 70 days for the three hosts evaluated. The eggs were laid in a spiral shape on the adaxial leaf surface. The 1st instars moved to short distances from the spiral, while the 2nd, 3rd and 4th are sessile and have bristles on the whole body. Based on the highest oviposition and the highest survival of the immature stage of the citrus blackfly in acid lime Tahiti, this plant can be considered the most suitable host to A. woglumi. (author)

  14. First record of occurrence of mosca-negra-dos-citrus, Aleurocanthus woglumi Ashby, 1915 (Hemiptera: Sternorrhyncha: Aleyrodidae in Roraima, Brazil = Primeiro registro da ocorrência de mosca-negra-dos-citros, Aleurocanthus woglumi Ashby, 1915 (Hemiptera: Aleyrodidae em Roraima

    Directory of Open Access Journals (Sweden)

    Francisco Clemilto da Silva Maciel


    Full Text Available The Aleurocanthus woglumi Ashby (Hemiptera: Aleyrodidae is an important pest of citrus. Originated in Asia, this pest was detected in Brazil for the first time in the State of Para, Brazil in 2001. In the culture of citrus fruits the black fly carries direct and indirect damage, impeding the development and production of plants. In addition to restricting trade in local areas from its occurrence to the presence of the plague, since the A. woglumi quarantine pest is considered present (A2 of high alert in accordance with Instruction No 23, April 29, 2008, established by the Ministério da Agricultura, Pecuária e Abastecimento of the Brazil. The objective of this paper was to record the first occurrence of Aleurocanthus woglumi in the State of Roraima, Brazil.= A mosca-negra-dos-citros, Aleurocanthus woglumi Ashb, (Hemiptera: Aleyrodidae é uma importante praga dos citros. De origem asiática, esta praga foi detectada no Brasil pela primeira vez no estado do Pará no ano de 2001. Na cultura dos citros a mosca-negra acarreta danos diretos e indiretos, prejudicando o desenvolvimento e produção das plantas. Além de restringir o comércio de locais de sua ocorrência para áreas livres da presença da praga, visto que o A. woglumi é considerado praga quarentenária presente (A2 de alerta máximo de acordo com a instrução normativa No 23, de 29 de abril de 2008; estabelecida pelo Ministério da Agricultura, Pecuária e Abastecimento. Objetivou-se com o presente trabalho registrar a primeira ocorrência de mosca-negra-dos-citros no estado de Roraima.

  15. Impacts of climate change in the ecoclimatology of Aleurocanthus Woglumi Ashby, 1903 (Hemiptera: Aleyrodidae in the state of Pará

    Directory of Open Access Journals (Sweden)

    Bergson Cavalcanti de Moraes


    Full Text Available Human activities that alter the greenhouse gases concentrations will have a direct influence on plant health issues. In order to minimize both the production loss and the quality, and to guide the choice of adaptation strategies and management, further studies to investigate the impacts of climate change on agriculture - in the spatial and temporal scales - and their pathogens are needed. The main goal of this work was to explore the global climate impact on the ecoclimatology of the citrus blackfly (Aleurocanthus woglumi Ashby in State of Pará. To do so, the thermal requirements of Aleurocanthus woglumi Ashby developed in laboratory and on the ecoclimatological zoning based on the annual insect population was first analyzed using air temperature data series from 15 meteorological stations. Then, the populational increase of the studied insect through the projections of global climate model CCSM 3.0, between years 2030 and 2090, was simulated and analyzed. The results of simulations suggest that the number of generations of the insect will increase 50% in Pará state.

  16. Observações sobre a ocorrência de Mosca-Negra-dos-Citros, Aleurocanthus woglumi Ashby, 1915 (Hemiptera: Sternorrhyncha: Aleyrodidae no estado do Amazonas Observation on the occurrence of the citrus blackfly Aleurocanthus woglumi Ashby, 1915 (Hemiptera: Sternorrhyncha: Aleyrodidae in the Amazonas state

    Directory of Open Access Journals (Sweden)

    Beatriz Ronchi-Teles


    Full Text Available A mosca-negra-dos-citros (Aleurocanthus woglumi Ashby é uma importante praga dos citros de origem asiática. Foi detectada no Brasil pela primeira vez em Belém-PA em 2001. Este trabalho tem como objetivo registrar a ocorrência de mosca-negra-dos-citros no estado do Amazonas, sua distribuição geográfica e estudos de biologia em condições de laboratório. A mosca-negra encontra-se atualmente disseminada em mais da metade dos municípios paraenses. No Amazonas foi detectada em junho de 2004 em Manaus e atualmente encontra-se disseminada em toda a área urbana deste município, ocorrendo também em Itacoatiara, Rio Preto da Eva e Iranduba. Em observações feitas em condições de laboratório em Manaus-AM, foi verificado que o ciclo de ovo-adulto foi de 71,76±2,07 dias, caracterizando como uma espécie multivoltina.The citrus blackfly Aleurocanthus woglumi Ashby, pest of citrus in Asian is considered important pest. It was detected for the first time in Belém, PA in 2001. The objective of this work was to report occurrence of the citrus blackfly in Amazon state. Nowadays is found in the majority of the oriental amazon counties. In Manaus, Amazonas was detected in June 2004, actually disseminated in the urban area and in Itacoatiara, Rio Preto da Eva and Iranduba counties. In observations in laboratory in Manaus-AM, was verified that the egg-adult cycle belonged to 71,76±2,07 days, characterizing as a multivoltin species.

  17. Influência de Fatores Abióticos na Infestação de Mosca-Negra-dos-Citros (Aleurocanthus woglumi Ashby em Plantio de Citros em Sistema Agroflorestal no Estado do Pará

    Directory of Open Access Journals (Sweden)

    Anderson Silva


    Abstract. An important part of citrus production at Pará state is planted by Agroforestry System (AFS, that presents, amongst major phytosanitary problems, the citrus blackfly, that by severe attacks cause estimated redution of 80% in its’ production. Beside that, it constitutes a quarentenary pest of maximun alert level A2. Given the relevance of this sucking insect and the lack of basic knowledge, as well pest studies associated to agroforestry planting, the objective of this study was to evaluate the abiotic factors influence on blackfly infestation in citrus planting by agroforestry planting at Pará state. This study was carried out at Capitão Poço county, northeast mesoregion of Pará. 12 samplings were made evaluating the presence or abscence of Aleurocanthus woglumi Ashby alive nymphs and/or adults. Correlation analisys was carried out to evaluate abiotic parameters (temperature and precipitation and kriging maps to evaluate Teca plants shading effects on the pest under study infestation. Amongst the main results obtained, there was pest infestation in every evaluated moth; there was temperature influence onto citrus blackfly population regulation and high precipitations reduced the number of plants with A. woglumi presence. Still, it can be inferred that the citrus blackfly infestations present preference for moderate shading intensity. However, changes occuring by the forestry species introduction onto agricultural cultivations must be better investigated.

  18. Preferência para oviposição e ciclo de vida de mosca-negra- dos-citros Aleurocanthus woglumi Ashby em espécies frutíferas

    Directory of Open Access Journals (Sweden)

    Gislane da Silva Lopes


    Full Text Available Aleurocanthus woglumi Ashby conhecida popularmente como mosca-negra-dos-citros é considerada praga quarentenária A2 no Brasil e ocasiona prejuízo em diversas frutíferas, principalmente em citros (laranja, limão e tangerina. Poucas são as pesquisas relacionadas aos seus aspectos biológicos nas condições ambientais brasileiras. Nesse sentido, o objetivo da pesquisa foi verificar a preferência de oviposição e a duração do ciclo de vida de A. woglumi em diferentes hospedeiros. A pesquisa foi conduzida em casa de vegetação, durante o período de março de 2009 a março de 2010. Foram realizados testes de preferência sem chance de escolha em seis hospedeiros, simultaneamente, em períodos de 48 e 72 horas, além da biologia comparada em mangueira e laranjeira. Foram observados nos testes que A. woglumi apresenta preferência por ovipositar nas espécies cítricas (limoeiro, laranjeira e tangerineira, mantendo um padrão de não preferência em cajueiro e goiabeira. Os hospedeiros laranjeira e mangueira não interferiram no ciclo biológico da praga.

  19. Work Loop and Ashby Charts of Active Materials (United States)


    were  lubricated  by a low viscosity machine oil (ν = 9.6 m2/s)  to minimize  friction. Different  actuation modes were obtained by  setting  appropriate...composite  transducers  (MAGACT),  Plenary  Presentation, in  Nano  2011, Cochin, India (2011)  8. R.  V.  Ramanujan,  V.Q. Nguyen  and  R.  Snyder

  20. Case note: EHRM (zaaknummer 36769/08: Ashby Donald ea/Frankrijk)

    NARCIS (Netherlands)

    Hugenholtz, P.B.


    Geaccrediteerde fotografen maken beeldmateriaal van Parijse modeshows beschikbaar op door hen beheerde website. Zij worden wegens auteursrechtinbreuk veroordeeld tot strafrechtelijke boetes en schadevergoeding aan modehuizen en hun beroepsvereniging. Verzoekers beroepen zich op hun vrijheid van meni


    Directory of Open Access Journals (Sweden)



    Full Text Available This paper aimed to verify the presence of black-fly of citrus in the state of Pernambuco in Brazil and wordwide. The material with symptoms were collected in the metropolitan area of Recife/PE and subsequently led to the identification in the Insect Biology Laboratory of the Federal Rural University of Pernambuco - UFRPE on February 4, 2011. The samples collected from the branches of citrus and bilocular, found the presence of eggs, nymphs, "pupae" and adults of Aleurocanthus woglumi, confirming its occurrence in the state of Pernambuco. The presence of blackfly of citrus had been detected in the city in the state of Pernambuco as Timbaúba, Bom Jardim, Macaparana, Axes, Orobo, São Vincent Farrer and Itambé in citrus plants. Before that had a suspect in the Valley Siriji/PE, now it is in the metropolitan area of Recife, therefore we can confirm that the material collected and identified in the metropolitan area of Pernambuco is A. woglumi.

  2. VizieR Online Data Catalog: SSDF survey: IRAC catalogs (Ashby+, 2013) (United States)

    Ashby, M. L. N.; Stanford, S. A.; Brodwin, M.; Gonzalez, A. H.; Martinez-Manso, J.; Bartlett, J. G.; Benson, B. A.; Bleem, L. E.; Crawford, T. M.; Dey, A.; Dressler, A.; Eisenhardt, P. R. M.; Galametz, A.; Jannuzi, B. T.; Marrone, D. P.; Mei, S.; Muzzin, A.; Pacaud, F.; Pierre, M.; Stern, D.; Vieira, J. D.


    We carried out our survey in a field that benefits from an abundance of supporting data from X-ray to radio wavelengths, and which has extremely low levels of Galactic dust emission, being among the cleanest 1% of contiguous 100deg2 regions on the sky as measured in the 100um IRAS map (Finkbeiner et al. 1999ApJ...524..867F). See section 2 for further details. The SSDF was covered by Astronomical Observation Requests (AORs) having coverage footprints of various (sometimes irregular) shapes and sizes. Although the four-AOR observations of specific areas were performed consecutively, spacecraft visibility constraints meant that coverage of the full SSDF had to be accumulated in separate campaigns spaced roughly six months apart. These took place in 2011 July-August, 2012 January-February, 2012 July-September, and 2012 December-2013 February. See section 3 for further explanations. (2 data files).

  3. VizieR Online Data Catalog: Star Formation Reference Survey (SFRS) (Ashby+, 2011) (United States)

    Ashby, M. L.; Mahajan, S.; Smith, H. A.; Willner, S. P.; Fazio, G. G.; Raychaudhury, S.; Zezas, A.; Barmby, P.; Bonfini, P.; Cao, C.; Gonzalez-Alfonso, C.; Ishihara, D.; Kaneda, H.; Lyttle, V.; Madden, S.; Papovich, C.; Sturm, E.; Surace, J.; Wu, H.; Zhu, Y. N.


    Star formation is arguably the most important physical process in the cosmos. It is a fundamental driver of galaxy evolution and the ultimate source of most of the energy emitted by galaxies. A correct interpretation of star formation rate (SFR) measures is therefore essential to our understanding of galaxy formation and evolution. Unfortunately, however, no single SFR estimator is universally available or even applicable in all circumstances: the numerous galaxies found in deep surveys are often too faint (or too distant) to yield significant detections with most standard SFR measures, and until now there have been no global, multi-band observations of nearby galaxies that span all the conditions under which star-formation is taking place. To address this need in a systematic way, we have undertaken a multi-band survey of all types of star-forming galaxies in the local Universe. This project, the Star Formation Reference Survey (SFRS), is based on a statistically valid sample of 369 nearby galaxies that span all existing combinations of dust temperature, SFR, and specific SFR. Furthermore, because the SFRS is blind with respect to AGN fraction and environment it serves as a means to assess the influence of these factors on SFR. Our panchromatic global flux measurements (including GALEX FUV+NUV, SDSS ugriz, 2MASS JHKs, Spitzer 3-8um, and others) furnish uniform SFR measures and the context in which their reliability can be assessed. This paper describes the SFRS survey strategy, defines the sample, and presents the multi-band photometry collected to date. (7 data files).

  4. Infestação da mosca-negra-dos-citros (Aleurocanthus woglumi Ashby em pomares de citros, em sistemas de plantio convencional e agroflorestal Infestation of citrus blackfly in citrus (Aleurocanthus woglumi Ashby orchards conventional and agroforestry

    Directory of Open Access Journals (Sweden)

    Anderson Gonçalves Da Silva


    Full Text Available Objetivou-se com o presente trabalho avaliar a infestação da mosca-negra-dos-citros em pomares de citros, em sistemas de plantio convencional e agroflorestal. A área experimental está localizada no município de Capitão Poço-PA, onde foram realizadas 12 amostragens durante o período de setembro de 2008 a outubro de 2009, avaliando a presença ou a ausência da praga nas laranjeiras, em ambos os sistemas de produção. Pelos resultados obtidos, observou-se que o sistema de plantio agroflorestal apresentou maior incidência de plantas com presença de mosca-negra-dos-citros comparado ao convencional, houve influência da temperatura na regulação da população da praga, e precipitações elevadas reduziram o número de plantas com presença de A. woglumi.The purpose of this study was to evaluate the infestation of citrus blackfly the in a citrus orchard in conventional tillage systems and agroforestry. The experimental area is located in the municipality of Capitão Poço, PA, where 12 samples were taken during the period from September 2008 to October 2009, evaluating the presence or absence of the pest in both production systems. The results showed that the system of agroforestry plantation showed higher incidence of plants with presence of citrus blackfly compared to conventional, there was influence of temperature on the regulation of pest population and heavy rain reduced the number of plants with presence of A.woglumi.

  5. Occurrence of Aleurocanthus woglumi Ashby, 1915 (Hemiptera: Aleyrodidae at Rio de Janeiro State = Ocorrência de Aleurocanthus woglumi Ashby, 1915 (Hemiptera: Aleyrodidae no Estado do Rio de Janeiro.

    Directory of Open Access Journals (Sweden)

    Márcio Coutinho de Almeida


    Full Text Available Citrus Blackfly’s, Aleurocanthus woglumi (Hemiptera: Aleyrodidae, is considered by the National Plant Protection Organization/Brazilian Ministry of Agriculture (NPPO/MAPA as a present quarantine pest (List A2, which occurs in 20 Brazilian States. The aim of this study is to report its occurrence in the Rio de Janeiro State, since its first notification in 2010. = A Mosca-Negra-dos-Citros, Aleurocanthus woglumi (Hemiptera: Aleyrodidae, é considerada pela Organização Nacional de Proteção Fitossanitária/Ministério da Agricultura (ONPF/MAPA, como praga quarentenária presente (Lista A2, com registros oficiais de ocorrência em 20 Estados brasileiros. O objetivo deste trabalho foi registrar sua ocorrência no Rio de Janeiro desde a sua primeira notificação, no ano de 2010.

  6. Surficial Geologic Map of the Ashby-Lowell-Sterling-Billerica 11-Quadrangle Area in Northeast-Central Massachusetts (United States)

    Stone, Byron D.; Stone, Janet R.


    The surficial geologic map shows the distribution of nonlithified earth materials at land surface in an area of eleven 7.5-minute quadrangles (total 505 mi2) in northeast-central Massachusetts. The geologic map differentiates surficial materials of Quaternary age on the basis of their lithologic characteristics (such as grain size and sedimentary structures), constructional geomorphic features, stratigraphic relationships, and age. Surficial earth materials significantly affect human use of the land, and an accurate description of their distribution is particularly important for water resources, construction aggregate resources, earth-surface hazards assessments, and land-use decisions. This compilation of surficial geologic materials is an interim product that defines the areas of exposed bedrock, and the boundaries between glacial till, glacial stratified deposits, and overlying postglacial deposits. This work is part of a comprehensive study to produce a statewide digital map of the surficial geology at a 1:24,000-scale level of accuracy. This report includes explanatory text (PDF), a regional map at 1:50,000 scale (PDF), quadrangle maps at 1:24,000 scale (PDF files), GIS data layers (ArcGIS shapefiles), metadata for the GIS layers, scanned topographic base maps (TIF), and a readme.txt file.

  7. Identifikasi Dan Uji Antagonisme Jamur Endofit Tanaman Tebu (Saccharum Officinarum L.) Terhadap Perkembangan Xanthomonas Albilineans L. Dengan Metode Sterilisasi Autoklaf Dan Membran Filter


    Wahyuni, Siti Hardianti


    This research was conducted in a Laboratory of Agricuture Faculty and greenhouse of Agricuture Faculty, North Sumatra University, Medan, from April until December 2014. The research used completely randomized design with three factors and three replications. The first factor were endophytic fungi 1, endophytic fungi 2, endophytic fungi 3, endophytic fungi 4, endophytic fungi 5, endophytic fungi 6, endophytic fungi 7, and endophytic fungi 8. The second factor were dilution 10-1, 10-2, 10-3 da...

  8. Pseudomonas cannabina pv. cannabina pv. nov., and Pseudomonas cannabina pv. alisalensis (Cintas Koike and Bull, 2000) comb. nov., are members of the emended species Pseudomonas cannabina (ex Sutic & Dowson 1959) Gardan, Shafik, Belouin, Brosch, Grimont & Grimont 1999. (United States)

    Bull, Carolee T; Manceau, Charles; Lydon, John; Kong, Hyesuk; Vinatzer, Boris A; Fischer-Le Saux, Marion


    Sequence similarity in the 16S rDNA gene confirmed that crucifer pathogen Pseudomonas syringae pv. alisalensis belongs to P. syringae sensu lato. In reciprocal DNA/DNA hybridization experiments, DNA relatedness was high (69-100%) between P. syringae pv. alisalensis strains and the type strain of P. cannabina (genomospecies 9). In contrast, DNA relatedness was low (below 48%) between P. syringae pv. alisalensis and reference strains from the remaining genomospecies of P. syringae including the type strain of P. syringae and reference strain of genomospecies 3 (P. syringae pv. tomato) although the well-known crucifer pathogen, P. syringae pv. maculicola, also belongs to genomospecies 3. Additional evidence that P. syringae pv. alisalensis belongs to P. cannabina was sequence similarity in five gene fragments used in multilocus sequence typing, as well as similar rep-PCR patterns when using the BOX-A1R primers. The description of P. cannabina has been emended to include P. syringae pv. alisalensis. Host range testing demonstrated that P. syringae pv. alisalensis strains, originally isolated from broccoli, broccoli raab or arugula, were not pathogenic on Cannabis sativa (family Cannabinaceae). Additionally, P. cannabina strains, originally isolated from the C. sativa were not pathogenic on broccoli raab or oat while P. syringae pv. alisalensis strains were pathogenic on these hosts. Distinct host ranges for these two groups indicate that P. cannabina emend. consists of at least two distinct pathovars, P. cannabina pv. cannabina pv. nov., and P. cannabina pv. alisalensis comb. nov. Pseudomonas syringae pv. maculicola strain CFBP 1637 is a member of P. cannabina.

  9. Materials Selection of Flexure Accelerometer Using Ashby Chart%基于Ashby图的挠性加速度计材料选择

    Institute of Scientific and Technical Information of China (English)

    刘小院; 白晓荣; 贾建援; 陈贵敏



  10. Probe into Ashby's Technological Humanism Thought%阿什比技术人文主义教育思想探析

    Institute of Scientific and Technical Information of China (English)




  11. Infestação da mosca-negra-dos-citros (Aleurocanthus woglumi Ashby em pomares de citros, em sistemas de plantio convencional e agroflorestal

    Directory of Open Access Journals (Sweden)

    Anderson Gonçalves Da Silva


    Full Text Available Objetivou-se com o presente trabalho avaliar a infestação da mosca-negra-dos-citros em pomares de citros, em sistemas de plantio convencional e agroflorestal. A área experimental está localizada no município de Capitão Poço-PA, onde foram realizadas 12 amostragens durante o período de setembro de 2008 a outubro de 2009, avaliando a presença ou a ausência da praga nas laranjeiras, em ambos os sistemas de produção. Pelos resultados obtidos, observou-se que o sistema de plantio agroflorestal apresentou maior incidência de plantas com presença de mosca-negra-dos-citros comparado ao convencional, houve influência da temperatura na regulação da população da praga, e precipitações elevadas reduziram o número de plantas com presença de A. woglumi.

  12. Flutuação populacional e dependência espacial de Aleurocanthus woglumi Ashby, 1915 (Hemiptera: Aleyrodidae em Citrus latifolia

    Directory of Open Access Journals (Sweden)

    Daniele Lavra Vieira


    Full Text Available A mosca-negra-dos-citros, Aleurocanthus woglumi, apresenta elevada capacidade de dispersão e adaptação a diversas condições climáticas, além de grande potencial reprodutivo. O presente trabalho teve como objetivo avaliar a flutuação populacional e caracterizar o padrão de dependência espacial de A. woglumi em um pomar de lima- ácida Tahiti (Citrus latifolia, Tanaka, no município de São José de Ribamar, Estado do Maranhão. Um sistema de posicionamento global (GPS e um sistema de informação geográfica (SIG foram usados para localizar os pontos das amostras, caracterizar o padrão de distribuição, calcular a área de agregação e elaborar mapas de distribuição dos adultos de mosca-negra-dos-citros dentro do pomar. O número médio total de moscas negras foi maior durante a estação chuvosa e observaram-se correlações significativas entre as variáveis precipitação pluvial, umidade relativa do ar e número total de adultos. A distribuição espacial A. woglumi no pomar é agregada, ajustando-se os variogramas calculados ao modelo esférico nas estações seca e chuvosa. Os insetos mostraram uma área de agregação média de 162.092 m² na estação chuvosa e de 9.615 m² na estação seca. Para se obter uma estimativa confiável de populações de mosca-negra-dos-citros, pelo menos uma armadilha deve ser usada a cada 17 hectares na estação chuvosa e uma armadilha por hectare na estação seca.

  13. Primeiro registro da ocorrência de mosca-negra-dos-citros, Aleurocanthus woglumi Ashby, 1915 (Hemiptera: Sternorrhyncha: Aleyrodidae) em Roraima.


    Correia, Ruy Guilherme; Lima, Antonio Cesar Silva; Farias,Paulo Roberto Silva; Maciel, Francisco Clemilton da Silva; Silva, Marcos Wanderley da; da Silva, Anderson Gonçalves


    A mosca-negra-dos-citros, Aleurocanthus woglumi Ashb, (Hemiptera: Aleyrodidae) é uma importante praga dos citros. De origem asiática, esta praga foi detectada no Brasil pela primeira vez no estado do Pará no ano de 2001. Na cultura dos citros a mosca-negra acarreta danos diretos e indiretos, prejudicando o desenvolvimento e produção das plantas. Além de restringir o comércio de locais de sua ocorrência para áreas livres da presença da praga, visto que o A. woglumi é considerado praga quarente...

  14. Dinâmica populacional da mosca-negra-dos-citros Aleurocanthus woglumi ashby (hemiptera: aleyrodidae em Citrus spp. no município de São Luís - MA Populational dynamics of citrus blackfly Aleurocanthus woglumi ashby (hemiptera: aleyrodidae in Citrus spp. in São Luís, Maranhão, Brazil

    Directory of Open Access Journals (Sweden)

    Fabíola Rodrigues Medeiros


    Full Text Available O objetivo deste trabalho foi avaliar a dinâmica populacional de Aleurocanthus woglumi ao longo de um ano, verificando-se a época de maior ocorrência, seus picos populacionais e a distribuição dessa praga em dois pomares de Citrus spp. no município de São Luís - MA. Para o estudo da dinâmica populacional, foram selecionadas 10 plantas ao acaso, em cada pomar, coletando-se 20 folhas por planta, no período de julho de 2006 a junho de 2007, contando-se o número de posturas, ovos e ninfas. Para a determinação da distribuição de A. woglumi, as plantas foram divididas em quadrantes: norte, leste, sul e oeste, retirando-se 5 folhas/quadrante, totalizando-se 200 folhas por área de coleta. Com relação à distribuição na planta, o delineamento foi o inteiramente casualizado, adotando-se o esquema fatorial 2 x 4 (período seco e chuvoso x quadrante, com 13 repetições (nº de coletas. Realizou-se uma análise exploratória de dados, e as médias obtidas foram submetidas ao teste de Tukey, a 5% de probabilidade. Observou-se, nas duas localidades, que o inseto se distribuiu na copa da árvore de maneira homogênea e que os maiores níveis populacionais de A. woglumi ocorreram no período de baixa precipitação (julho a dezembro de 2006.This paper aims to evaluate the populational dynamics of Aleurocanthus woglumi throughout one year, verifying the season with higher density, its populational peaks and citrus blackfly distribution in Citrus spp. in two orchards, in São Luís, Maranhão, Brazil. To study the populational dynamics, 10 plants were selected at random, in each orchard, as well as 20 leaves per plant, from July 2006 to June 2007, and the number of layings, eggs and nymphs was counted. To determine the vertical distribution of A. woglumi, plants were divided into quadrants: North, East, South and West, and 5 leaves/quadrant were removed, totaling 200 leaves per collecting area. Regarding to distribution over the plant, the delineation was entirely randomized adopting a 2 x 4 factorial scheme (dry and rainy seasons x quadrants, with 13 repetitions (number of collections. It accomplished an exploratory analysis of data and averages submitted to Tukey test at a 5% probability rate. It was observed that on the two locations the insect was distributed homogeneous on the tree canopies and that the highest populational levels of A. woglumi occurred in the low precipitation season (from July to December 2006.

  15. 77 FR 29648 - Medicare and Medicaid Programs; Quarterly Listing of Program Issuances-January Through March 2012 (United States)


    ...-Related Guidance Documents.. Lori Ashby (410) 786-6322 X One-time Notices Regarding National Coverage Provisions. Lori Ashby (410) 786-6322 XI National Oncologic Positron Emission Tomography Stuart Caplan,...

  16. 78 FR 11189 - Medicare and Medicaid Programs; Quarterly Listing of Program Issuances-October Through December 2012 (United States)


    ... Coverage- Lori Ashby......... (410) 786-6322 Related Guidance Documents. X One-time Notices Regarding Lori Ashby......... (410) 786-6322 National Coverage Provisions. XI National Oncologic Positron Stuart...

  17. 75 FR 70067 - Notice of Request for Reinstatement of Previously Approved Information Collection (United States)


    ... forth below. Correction FOR FURTHER INFORMATION CONTACT: Robert C. Ashby, Office of the . SUPPLEMENTARY INFORMATION: Number of Respondents: 1,250. Frequency of Response:...

  18. 77 FR 67368 - Medicare and Medicaid Programs; Quarterly Listing of Program Issuances-July through September 2012 (United States)


    ... Coverage- Lori Ashby......... (410) 786-6322 Related Guidance Documents. X One-Time Notices Regarding Lori Ashby......... (410) 786-6322 National Coverage Provisions. XI National Oncologic Positron Stuart...

  19. 75 FR 16357 - Participation by Disadvantaged Business Enterprises in Airport Concessions (United States)


    .... FOR FURTHER INFORMATION CONTACT: Robert C. Ashby, Deputy Assistant General Counsel for Regulation and...-302, 202-366-9310, . SUPPLEMENTARY INFORMATION: When the Department issued its...

  20. 75 FR 47753 - Transportation for Individuals With Disabilities (United States)


    ... INFORMATION CONTACT: Robert C. Ashby, Deputy Assistant General Counsel for Regulation and Enforcement... (voice); (202) 366-7687 (TDD); (e-mail). SUPPLEMENTARY INFORMATION: On February...

  1. 75 FR 36463 - Notice of Request for Renewal of a Previously Approved Collection (United States)


    ... FURTHER INFORMATION CONTACT: Mr. Robert C. Ashby, Office of the Secretary, Office of Assistant General... 20590, (202) 366-9310 (voice) (202) 366-9313 (fax) or at . SUPPLEMENTARY..., DC, on June 21, 2010. Robert C. Ashby, Deputy Assistant General Counsel for Regulation...

  2. 76 FR 69198 - Proposed Establishment of the Middleburg Virginia Viticultural Area (United States)


    ... western breezes from the Ashby Gap in the Blue Ridge Mountains, dissipate the morning fog, lessen the..., Virginia, 1994; (12) Ashby Gap Quadrangle, Virginia, 1970, photorevised 1978, photoinspected 1981; and (13..., crossing onto the Ashby Gap map, to U.S. Route 50 (just east of Paris); then (28) Proceed...

  3. 75 FR 5369 - Approved Information Collection Extension Request; Disadvantaged Business Enterprise (United States)


    ... CONTACT: Mr. Robert C. Ashby, Office of the Secretary, Office of Assistant General Counsel for Regulation...) 366-9310 (voice), 202-366-9313 (fax) or at . SUPPLEMENTARY INFORMATION: Title... public record. ] Issued in Washington, DC, on January 28, 2010. Robert C. Ashby, Deputy Assistant...

  4. 76 FR 22084 - Applications for New Awards; Rehabilitation Training: Rehabilitation Long-Term Training (United States)


    ... or fax your statement to: RoseAnn Ashby, U.S. Department of Education, 400 Maryland Avenue, SW., room... FURTHER INFORMATION CONTACT: RoseAnn Ashby, U.S. Department of Education, Rehabilitation Services... or by e-mail: . If you use a TDD, call the FRS, toll free, at...

  5. 78 FR 16447 - Rehabilitation Continuing Education Program (RCEP) for the Technical Assistance and Continuing... (United States)


    ... extension of project period and waiver to RoseAnn Ashby, U.S. Department of Education, 400 Maryland Avenue... by email, use the following address: . You must include the phrase ``Proposed... CONTACT: RoseAnn Ashby at the address listed in the ADDRESSES section of this notice. Telephone: (202)...

  6. 78 FR 35808 - Proposed priority-Rehabilitation Training: Rehabilitation Long-Term Training Program-Vocational... (United States)


    ..., 2013. ADDRESSES: Address all comments about this notice to RoseAnn Ashby, U.S. Department of Education... prefer to send your comments by email, use the following address: . You must include.... FOR FURTHER INFORMATION CONTACT: RoseAnn Ashby. Telephone: (202) 245- 7258. If you use...

  7. Distance Education: Growth in Distance Education Programs and Implications for Federal Education Policy. Testimony before the Committee on Health, Education, Labor, and Pensions, U.S. Senate. Statement of Cornelia M. Ashby, Director, Education, Workforce, and Income Security Issues. (United States)

    General Accounting Office, Washington, DC.

    Data from the National Postsecondary Student Aid Study (NPSAS) supported testimony given before the Senate Committee on Health, Education, Labor and Pensions. The testimony focused on four factors: (1) demographic characteristics of distance education students and institutional characteristics of postsecondary schools offering distance education;…

  8. Jane Dawson & Alice Entwistle. A History of Twentieth-Century British Women’s Poetry

    Directory of Open Access Journals (Sweden)

    Rainer EMIG


    Full Text Available A gigantic task well executed, this is what Dowson and Entwistle’s book turns out to be. It takes the bull (or should it be the cow, the mad cow of Jo Shapcott’s amusing poems? by the horns and tries to come up with a possible history of the many diverse and often uncollected female voices in Britain in the twentieth century. Dowson and Entwistle’s definition of “British Women’s Poetry” is flexible: “The following poets are British born, published in Britain and/or judged to have made a sign...

  9. Identifying target properties for the design of meta-material tank track pads (United States)


    exists to create a material that fills the void in the Ashby chart [6] shown in Figure 3. The new material would need to exhibit a low loss coefficient...linear elastic material, which lead to the behavior depicted by the meta-material region described in the Ashby chart, need to be determined. The...Figure 3. Ashby chart [6]: meta-material characterization 3 FINITE ELEMENT ANALYSIS (FEA) For the present analysis, a 2nd order Ogden Hyperelastic

  10. Remarks on Ashby's View on University Transplanting%阿什比的大学移植观浅析--读《英国、印度和非洲的大学:高等教育生态学研究》

    Institute of Scientific and Technical Information of China (English)




  11. Genomes-based phylogeny of the genus Xanthomonas

    Directory of Open Access Journals (Sweden)

    Rodriguez-R Luis M


    Full Text Available Abstract Background The genus Xanthomonas comprises several plant pathogenic bacteria affecting a wide range of hosts. Despite the economic, industrial and biological importance of Xanthomonas, the classification and phylogenetic relationships within the genus are still under active debate. Some of the relationships between pathovars and species have not been thoroughly clarified, with old pathovars becoming new species. A change in the genus name has been recently suggested for Xanthomonas albilineans, an early branching species currently located in this genus, but a thorough phylogenomic reconstruction would aid in solving these and other discrepancies in this genus. Results Here we report the results of the genome-wide analysis of DNA sequences from 989 orthologous groups from 17 Xanthomonas spp. genomes available to date, representing all major lineages within the genus. The phylogenetic and computational analyses used in this study have been automated in a Perl package designated Unus, which provides a framework for phylogenomic analyses which can be applied to other datasets at the genomic level. Unus can also be easily incorporated into other phylogenomic pipelines. Conclusions Our phylogeny agrees with previous phylogenetic topologies on the genus, but revealed that the genomes of Xanthomonas citri and Xanthomonas fuscans belong to the same species, and that of Xanthomonas albilineans is basal to the joint clade of Xanthomonas and Xylella fastidiosa. Genome reduction was identified in the species Xanthomonas vasicola in addition to the previously identified reduction in Xanthomonas albilineans. Lateral gene transfer was also observed in two gene clusters.

  12. VizieR Online Data Catalog: Spitzer/IRAC variability survey of Bootes field (Kozlowski+, 2016) (United States)

    Kozlowski, S.; Kochanek, C. S.; Ashby, M. L. N.; Assef, R. J.; Brodwin, M.; Eisenhardt, P. R.; Jannuzi, B. T.; Stern, D.


    A detailed description of Spitzer Deep Wide-Field Survey (SDWFS) is presented in Ashby et al. (2009, see J/ApJ/716/530). The first epoch was taken on 2004 January 10-14 as the IRAC Shallow Survey (Eisenhardt et al. 2004ApJS..154...48E). Then, we added three more epochs on 2007 August 8-13, 2008 February 2-6, and 2008 March 6-10 as the SDWFS (Ashby et al. 2009, see J/ApJ/716/530; D. Stern PI, PID 40839). The new, fifth epoch was taken on 2014 April 23-29 as the Decadal IRAC Bootes Survey (DIBS; M.L.N. Ashby PI, PID 10088). The intervals between any two epochs span the range from 1 month to 10 years. (3 data files).

  13. A New Viscosity-Pressure Formula for Calculating Viscosity from Density of Lubricating Oils%由润滑油密度求黏度的新黏压关系式探讨

    Institute of Scientific and Technical Information of China (English)

    崔金磊; 杨萍; 刘晓玲; 杨沛然



  14. Primer registro de "la mosca negra de los cítricos" Aleurocanthus woglumi (Hemiptera: Aleyrodidae en la Argentina First record of the citrus blackfl y Aleurocanthus woglumi (Hemiptera: Aleyrodidae in Argentina

    Directory of Open Access Journals (Sweden)

    Silvia N. López


    Full Text Available Aleurocanthus woglumi Ashby es una especie polífaga que ataca principalmente cultivos de Citrus spp. El objetivo de este trabajo es dar a conocer la primera detección de A. woglumi en Argentina. Los especímenes estudiados fueron recolectados en cultivos de pomelo en Tres Lagunas, departamento de Pilagá, Formosa, en febrero de 2011.Aleurocanthus woglumi Ashby is a polyphagous pest that attacks mainly Citrus spp. The objective of this paper is to report the first detection of this species in Argentina. Studied specimens were collected from grapefruit crops at Tres Lagunas, department of Pilagá, Formosa, in February, 2011.

  15. Comparison of prostate gene expression and tissue weight changes as monitors of antiandrogen activity in GNRH-inhibited rats

    DEFF Research Database (Denmark)

    Nellemann, Christine Lydia; Lefevre, P. A.; Ashby, J.


    BACKGROUND: The Hershberger assay for antiandrogens and modifiers of steroid biosynthesis uses surgically-castrated rats. We described an adaptation of the assay using the GnRH inhibitor Antarelix in place of surgical castration [Ashby J, Lefevre PA, Deghenghi R, Wallis N. Regulatory Toxicology...

  16. Graph-based Models for Data and Decision Making (United States)


    LESLIE M. BLAHA ROBERT C. MCKINLEY Work Unit Manager Chief, Battlespace Visualization Branch Battlespace Visualization Branch Warfighter...differences in capacity coefficient data. Aspects of this technique were published in a 2015 conference proceedings paper; the full technique will appear...parallel pred ictions. Psychological Review, 119, 500-516. Townsend, J . T., & Ashby, F. G. (1983). The stochastic modeling of elementary

  17. Characterization of free nitrogen fixing bacteria of the genus Azotobacter in organic vegetable-grown Colombian soils

    NARCIS (Netherlands)

    Jiménez Avella, Diego; Montaña, José Salvador; Martínez, María Mercedes


    With the purpose of isolating and characterizing free nitrogen fixing bacteria (FNFB) of the genus Azotobacter, soil samples were collected randomly from different vegetable organic cultures with neutral pH in different zones of Boyacá-Colombia. Isolations were done in selective free nitrogen Ashby-

  18. Homogenization of steady-state creep of porous metals using three-dimensional microstructural reconstructions

    DEFF Research Database (Denmark)

    Kwok, Kawai; Boccaccini, Dino; Persson, Åsa Helen;


    The effective steady-state creep response of porous metals is studied by numerical homogenization and analytical modeling in this paper. The numerical homogenization is based on finite element models of three-dimensional microstructures directly reconstructed from tomographic images. The effects ...... model, and closely matched by the Gibson-Ashby compression and the Ramakrishnan-Arunchalam creep models. [All rights reserved Elsevier]....

  19. The Interpersonal Relationships and Social Perceptions of Adolescent Perfectionists (United States)

    Gilman, Rich; Adams, Ryan; Nounopoulos, Alex


    This study investigated the relationship between multidimensional perfectionism, self-reported interpersonal relationships, and peer-reported prosocial, disruptive, and academic behaviors among a general sample of 984 9th-grade adolescents. Cut-scores from the "Almost Perfect Scale-Revised" (APS-R; Slaney, Rice, Mobley, Trippi, & Ashby, 2001)…

  20. An Intelligence Collection Management Model. (United States)


    classification of inteligence collection requirements in terms of. the a-.- metnodo"c, .ev--e in Chaster Five. 116 APPgENDIX A A METHOD OF RANKING...of Artificial Intelligence Tools and Technigues to!TN’X n~l is n rs aa~emfft-.3-ufnyva: ’A TZ Ashby W. Ecss. An Introduction to Cybernetics. New York

  1. Polymer Nanocomposites with Prescribed Morphology: Going Beyond Nanoparticle-Filled Polymers (Preprint) (United States)


    also been observed.100 Pickering emulsions ( emulsions stabilized by solid par- ticles) using nanoparticles also offer interesting possibilities... Pickering emulsions are encountered in various natural and industrial processes such as crude oil recovery, oil separation, cosmetic preparation, and...agarose after assembly of magnetite nanoparticles at the interface.105 Ashby and Binks106 reported Pickering emulsions using laponite. Additionally, N

  2. Multifunctional Mechatronic Materials (United States)


    actuating structures based on the properties of the Kagome system. This final report contains the following studies: (1) Effective Properties of the Octet...truss Lattice Material, by V.S. Deshpande, N.A. Fleck, and M.F. Ashby; (2) Kagome Plate Structures for Actuation, by R.G. Hutchinson, N. Wicks, A.G

  3. Individual and Family Perfectionism and Its Relationship to Depression, Anxiety, and Self-Esteem among Latino College Students (United States)

    Ortega, Norma E.


    This study examined the relationship between individual and family perfectionism and mental health functioning among two hundred and seven Latino college students. One aim of this study was to test the factor structure of the Almost Perfect Scale-Revised (APS-R; Slaney, Rice, Mobley, Trippi, & Ashby, 2001) with Latino college students by…

  4. Perfectionism, Depression, Loneliness, and Life Satisfaction: A Study of High School Students in Hong Kong (United States)

    Wang, Kenneth T.; Yuen, Mantak; Slaney, Robert B.


    This study investigates the cross-cultural construct validity of perfectionism using the Chinese translation of the Almost Perfect Scale-Revised (APS-R; Slaney, Mobley, Trippi, Ashby, & Johnson, 1996) with 509 Chinese high school students from Hong Kong. The factor structure of the Chinese APS-R and correlations between the APS-R subscales and…

  5. The Interrelationships among Coping Resources, Gender Role Stress, Self-Efficacy, and Anxiety in University Women Enrolled in Graduate Counseling Programs (United States)

    Kordansky, Jessica B.


    College-age women are affected by anxiety disorders at a significant rate. The data suggest that enhancing a sense of control over the negative effects of life events has a greater positive effect on women than men (Matheny, Ashby, & Cupp, 2005). While there is a literature base for stress coping among undergraduate students (McCarthy,…

  6. Tests of a Prior Marksmanship Knowledge Predictor Test (United States)


    because they received some marksmanship instruction before completing the test. However, it is important to also keep in mind that the timing of...Spiering, B. J. (2007). A neurobiological theory of automaticity in perceptual categorization. Psychological Review, 114(3), 632. Ashby, F. G

  7. Analysis of High Energy Laser Weapon Employment from a Navy Ship (United States)


    batteries, capacitors , flywheel, etc.). In this section, lead acid batteries are considered to provide 2 MW (round up from 1.9 MW) and 6.5 MW... Polypropylene : The definitive users guide. Norwich: Plastic Design Library. Ashby, M., & Johnson, K. (2012). Materials and design. Burlington: Elsevier Ltd

  8. The Teacher’s Role of Listening Comprehension

    Institute of Scientific and Technical Information of China (English)

    WANG Yun


    Throughout the history of the listening comprehension teaching at home and abroad, the research mainly focus on the correlation of the learner’s English listening proficiency and their self-efficiency. Scholars like Alisa J.Bates, Penny Ur. and Wid⁃dowson, H. G. have claimed the significance of teacher’s role in listening comprehension. For the purpose of proving the necessi⁃ty of the teacher’s role in listening comprehension, based on the analysis of the features of classroom listening comprehension, this paper presents the teacher’s role before class, in class and after class. Meanwhile, during the teaching process, teachers and learners are revealed in two way interactive relations and the pedagogical process is the result of the bilateral interaction of the two sides.

  9. Compressibilities and viscosities of reference, vegetable, and synthetic gear lubricants

    DEFF Research Database (Denmark)

    Regueira Muñiz, Teresa; Lugo, Luis; Fernández, Josefa


    .06%. Dowson and Higginson and Zhu and Wen equations of state do not predict well the isothermal compressibilities, with AAD % being around 45% for both equations. Moreover, the viscosities were measured in the temperature range from 278.15 to 373.15 K at atmospheric pressure for these oils, and the viscosity...... index was also determined. New formulated oils present the highest viscosity indexes and the lowest viscosity data at low temperatures; therefore, they become the most suitable for machinery cold start. © 2014 American Chemical Society.......Nowadays, one of the primary choices of base oils for environmentally aware lubricants is vegetable oils. This is due to their good natural biodegradability and very low toxicity in combination with very good lubricity characteristics. The development of new vegetable-based lubricants requires...

  10. Special Operations Forces: A Global Immune System?

    CERN Document Server

    Norman, Joseph


    The use of special operations forces (SOF) in war fighting and peace keeping efforts has increased dramatically in recent decades. A scientific understanding of the reason for this increase would provide guidance as to the contexts in which SOF can be used to their best effect. Ashby's law of requisite variety provides a scientific framework for understanding and analyzing a system's ability to survive and prosper in the face of environmental challenges. We have developed a generalization of this law to extend the analysis to systems that must respond to disturbances at multiple scales. This analysis identifies a necessary tradeoff between scale and complexity in a multiscale control system. As with Ashby's law, the framework applies to the characterization of successful biological and social systems in the context of complex environmental challenges. Here we apply this multiscale framework to provide a control theoretic understanding of the historical and increasing need for SOF, as well as conventional mili...

  11. Effect of residual stress on cavitation instabilities in constrained metal wires

    DEFF Research Database (Denmark)

    Tvergaard, Viggo


    Numerical calculations are carried out for a test specimen geometry used by Ashby et al. to study effects of ductile reinforcements in brittle materials. A lead wire well bonded to an outer glass cylinder was used to investigate crack bridging by ductile particles. The main focus here is on a sin......Numerical calculations are carried out for a test specimen geometry used by Ashby et al. to study effects of ductile reinforcements in brittle materials. A lead wire well bonded to an outer glass cylinder was used to investigate crack bridging by ductile particles. The main focus here...... is on a single void growing very large in the metal wire, in the crack plane, perhaps involving a cavitation instability. Therefore, full finite strain elastic-plastic theory is used for the analyses, and remeshing procedures are applied to avoid unacceptable mesh distortion. Residual stresses induced by thermal...

  12. STS-93: Columbia, Flight Crew Training with M-113 for Chandra (United States)


    Live footage shows the crewmembers, Commander Eileen M. Collins, Pilot Jeffrey S. Ashby, and Mission Specialists Steven A. Hawley, Catherine G. Coleman, and Michel Tognini, standing in front of an M-113 armored personnel carrier vehicle, and posing for photographs. Footage also includes the crew inside the vehicle getting quick instructions on how to operate the vehicle. They are also seen taking turns in driving the vehicle, and taking photographs and recording each other as one member of the crew drives the vehicle.

  13. Quantitative Technology Assessment (QTA). Delivery Order 0007: Vehicle Design Technology Developments for Uninhabited Aerial Systems (UAS) (United States)


    the RNN and dn is the corresponding desired response, direct application of the EKF to the dynamic system composing the RNN becomes: [ ] 1,11...continuously varied to deliver maximum power to the sample. When the voltage and current reach levels predetermined to correspond to a sufficiently high...version by Gibson and Ashby allowing for shear deformation, which has been successfully used as a basis by Olympio and Gandhi to model hybrid and

  14. Maintenance Enterprise Resource Planning: Information Value Among Supply Chain Elements (United States)


    3879. doi:10.1080/00207543.2012.752587 Ashby, W. R. (1947). Principles of the self-organizing dynamic system. The Journal of General Psychology , 37...Teaching of Psychology , 8(1), 35– 38. doi:10.1207/s15328023top0801_10 Bertalanffy, L. Von. (1969). General system theory: Foundations, development...Bertalanffy’s “general system theory: Foundations, development, applications.” Gestalt Theory, 26(1), 44–57. Halldorsson, A., Kotzab, H., Mikkola, J. H


    Directory of Open Access Journals (Sweden)

    Olena Loza


    Full Text Available Artykuł zawiera analizę pojęcia „perfekcjonizm” jako właściwości psychicznej. Rozpatrzono definicje per- fekcjonizmu, wskazano na jego związki z osobowością, przedstawiono odpowiednie modele: Frost, Marten, Lahart i Rosenblate (1990, Hewitt i Flett (1991, Slaney, Mobley, Tripp i Ashby (2001, Garanian (Гаранян 2009. Na podstawie tej analizy zaproponowano autorski model perfekcjonizmu.

  16. Styrene-based shape memory foam: fabrication and mathematical modeling (United States)

    Yao, Yongtao; Zhou, Tianyang; Qin, Chao; Liu, Yanju; Leng, Jinsong


    Shape memory polymer foam is a promising kind of structure in the biomedical and aerospace field. Shape memory styrene foam with uniform and controlled open-cell structure was successfully fabricated using a salt particulate leaching method. Shape recovery capability exists for foam programming in both high-temperature compression and low-temperature compression (Ashby as well as differential micromechanics theory were applied to predict Young’s modulus and the mechanical behavior of SMP styrene foams during the compression process.

  17. Theoretical Sources and Bases of Pedagogy of Collective Creative Education

    Directory of Open Access Journals (Sweden)

    Kaplunovich I. Ya.


    Full Text Available Known pedagogical concept of I. P. Ivanov considered and analyzed from the perspective of two sciences: psychology and cybernetics. It is shown that the basic principles of pedagogy common concern based implicitly and may be explained in particular on the fundamental positions of the two classical disciplines (Ashby laws, the second principle, the initial threshold of complexity, etc. in cybernetics and cultural-historical and activity approach in psychology.

  18. Propriétés effectives de matériaux architecturés


    Dirrenberger, Justin


    Architectured materials bring new possibilities in terms of structural and functional properties, filling gaps and pushing the boundaries of Ashby's materials maps. The term "architectured materials" encompasses any microstructure designed in a thoughtful fashion, so that some of its materials properties have been improved. There are many examples: particulate and fibrous composites, foams, sandwich structures, woven materials, lattice structures, etc. One engineering challenge is to predict ...

  19. A Transactions Cost Economics Approach to Defense Acquisition Management (United States)


    and economic organization. American Economic Review , 62, 777-795. Ashby, W. R. (1960). An introduction to cybernetics. London: Chapman & Hall... American Economic Review , 77, 168-185. Kadish et al. (2005, December). Defense acquisition performance assessment for the Acting Deputy Secretary...k^s^i=mlpqdo^ar^qb=p`elli= = Krueger, A. (1974). The political economy of the rent-seeking society. American Economic Review , 64, 291-303. Levy, B

  20. Image Processing Language. Phase 2. (United States)


    variety of the communication in the sense of Ashby (Reference 31), Bandler (Reference 32), Bandler and Grinder (Reference 33 and 34), Klir (Reference 4...L. Bandler , They Lived Happily Ever After, Meta Publications, Meta Publications, Cupertino, CA, 1978. 33. R. Bandler and J. Grinder, The Structure...of Magic, Vol. 1, Science and Behavior Books, Palo Alto, CA, 1975. 34. R. Bandler and J. Grinder, The Structure of Magic, Vol. 2, Science and Behavior

  1. Primer registro de “la mosca negra de los cítricos” Aleurocanthus woglumi (Hemiptera: Aleyrodidae en la Argentina

    Directory of Open Access Journals (Sweden)

    Silvia N. LÓPEZ


    Full Text Available Aleurocanthus woglumi Ashby es una especie polífaga que ataca principalmente cultivos de Citrus spp. El objetivo de este trabajo es dar a conocer la primera detección de A. woglumi en Argentina. Los especímenes estudiados fueron recolectados en cultivos de pomelo en Tres Lagunas, departamento de Pilagá, Formosa, en febrero de 2011.

  2. Organizational and Systems Theory: An Integrated Review (United States)


    because it was this type with which Darwin was concerned in his studies of biological species as systems. Numerous authors--including Ashby (1960), Marney...bases of social power. In D. Cartwright (Ed.), Studies in social ower. Ann Arbor: University of Michigan Institut for Social Research, 1959...N •274 2* 4" * *.* * .*I Guetzkow, H. E. Differentittion of roles in task-oriented tasks. In D. Cartwright , a’ A. Zander (jEds.), GrouT dynamics

  3. A Study of Slipper and Rail Wear Interaction at Low Speed (United States)


    taking care of the boys, a house and a dog and for not getting discouraged. I pray that they will learn as I have how important it is to ensure Yahovah...wear, delamination wear, seizure wear, melt wear, severe oxidational wear and adhesive wear. Adhesive wear comprised of three zones: low speed...model is experiencing seizure or melt wear, then something is wrong with the model. Lim and Ashby also published on their wear map the normalized wear

  4. Ammonia in simulated Hanford double-shell tank wastes: Solubility and effects on surface tension

    Energy Technology Data Exchange (ETDEWEB)

    Norton, J.D.; Pederson, L.R.


    Radioactive and wastes left from defense materials production activities are temporarily stored in large underground tanks at the Hanford Site in south central Washington State (Tank Waste Science Panel 1991). Some of these wastes are in the form of a thick slurry (``double-shell slurry``) containing sodium nitrate, sodium nitrite, sodium aluminate, sodium hydroxide, sodium carbonate, organic complexants and buffering agents, complexant fragments and other minor components (Herting et al. 1992a; Herting et al. 1992b; Campbell et al. 1994). As a result of thermal and radiolytic processes, a number of gases are known to be produced by some of these stored wastes, including ammonia, nitrous oxide, nitrogen, hydrogen, and methane (Babad et al. 1991; Ashby et al. 1992; Meisel et al. 1993; Ashby et al. 1993; Ashby et al. 1994; Bryan et al. 1993; US Department of Energy 1994). Before the emplacement of a mixer pump, these gases were retained in and periodically released from Tank 241-SY-101, a double-shell tank at the Hanford Site (Babad et al. 1992; US Department of Energy 1994). Gases are believed to be retained primarily in the form of bubbles attached to solid particles (Bryan, Pederson, and Scheele 1992), with very little actually dissolved in the liquid. Ammonia is an exception. The relation between the concentration of aqueous ammonia in such concentrated, caustic mixtures and the ammonia partial pressure is not well known, however.

  5. Creep Damage Analysis of a Lattice Truss Panel Structure (United States)

    Jiang, Wenchun; Li, Shaohua; Luo, Yun; Xu, Shugen


    The creep failure for a lattice truss sandwich panel structure has been predicted by finite element method (FEM). The creep damage is calculated by three kinds of stresses: as-brazed residual stress, operating thermal stress and mechanical load. The creep damage at tensile and compressive loads have been calculated and compared. The creep rate calculated by FEM, Gibson-Ashby and Hodge-Dunand models have been compared. The results show that the creep failure is located at the fillet at both tensile and creep loads. The damage rate at the fillet at tensile load is 50 times as much as that at compressive load. The lattice truss panel structure has a better creep resistance to compressive load than tensile load, because the creep and stress triaxiality at the fillet has been decreased at compressive load. The maximum creep strain at the fillet and the equivalent creep strain of the panel structure increase with the increase of applied load. Compared with Gibson-Ashby model and Hodge-Dunand models, the modified Gibson-Ashby model has a good prediction result compared with FEM. However, a more accurate model considering the size effect of the structure still needs to be developed.

  6. Some basic properties of environmentally adapted oils

    Energy Technology Data Exchange (ETDEWEB)

    Hoeglund, E. [Div. of Machine Elements, Luleaa University of Technology (Sweden)


    Environmental concern has led to a development of lubricants that are less harmful to the environmental than traditional mineral based oils. Biodegradability and non-toxicity are desired properties together with a competitive price and if possible they should also be derived from renewable raw materials. In order to have a major breakthrough for the new, environmentally adapted lubricating oils they must perform well in mechanical and hydraulic systems. They must reduce wear, increase efficiency and reduce maintenance costs equally well, or preferably better than mineral based oils. This paper presents primary results from an investigation where four environmentally adapted oils (rape seed, pine tree, diester and TMP-ester) are compared to a conventional naphthenic mineral oil. Viscosity and viscosity-pressure coefficients, limiting shear stress, friction properties and film forming ability have been evaluated under elastohydrodynamic conditions. It was found that the mineral oil had the highest values of pressure-viscosity coefficient, limiting shear stress and coefficient of friction. Rape seed oil had the second highest pressure-viscosity coefficient but the lowest limiting shear stress and coefficient of friction. Pine tree oil, diester and TMP-ester formed an intermediate group with rather similar results. The Hamrock-Dowson equation for central film thickness was found to overestimate film thickness by about 10-20 per cent with the least discrepancy for the mineral oil. (orig.) 8 refs.

  7. Bio-tribology. (United States)

    Dowson, Duncan


    It is now forty six years since the separate topics of friction, lubrication, wear and bearing design were integrated under the title 'Tribology' [Department of Education and Science, Lubrication (Tribology) Education and Research. A Report on the Present Position and Industry's Needs, HMSO, London, 1966]. Significant developments have been reported in many established and new aspects of tribology during this period. The subject has contributed to improved performance of much familiar equipment, such as reciprocating engines, where there have been vast improvements in engine reliability and efficiency. Nano-tribology has been central to remarkable advances in information processing and digital equipment. Shortly after widespread introduction of the term tribology, integration with biology and medicine prompted rapid and extensive interest in the fascinating sub-field now known as Bio-tribology [D. Dowson and V. Wright, Bio-tribology, in The Rheology of Lubricants, ed. T. C. Davenport, Applied Science Publishers, Barking, 1973, pp. 81-88]. An outline will be given of some of the developments in the latter field.

  8. Feedback can be superior to observational training for both rule-based and information-integration category structures. (United States)

    Edmunds, C E R; Milton, Fraser; Wills, Andy J


    The effects of two different types of training on rule-based and information-integration category learning were investigated in two experiments. In observational training, a category label is presented, followed by an example of that category and the participant's response. In feedback training, the stimulus is presented, and the participant assigns it to a category and then receives feedback about the accuracy of that decision. Ashby, Maddox, and Bohil (2002. Observational versus feedback training in rule-based and information-integration category learning. Memory & Cognition, 30, 666-677) reported that feedback training was superior to observational training when learning information-integration category structures, but that training type had little effect on the acquisition of rule-based category structures. These results were argued to support the COVIS (competition between verbal and implicit systems) dual-process account of category learning. However, a number of nonessential differences between their rule-based and information-integration conditions complicate interpretation of these findings. Experiment 1 controlled between-category structures for participant error rates, category separation, and the number of stimulus dimensions relevant to the categorization. Under these more controlled conditions, rule-based and information-integration category structures both benefited from feedback training to a similar degree. Experiment 2 maintained this difference in training type when learning a rule-based category that had otherwise been matched, in terms of category overlap and overall performance, with the rule-based categories used in Ashby et al. These results indicate that differences in dimensionality between the category structures in Ashby et al. is a more likely explanation for the interaction between training type and category structure than the dual-system explanation that they offered.

  9. Cybernetic brain sketches of another future

    CERN Document Server

    Pickering, Andrew


    Cybernetics is often thought of as a grim military or industrial science of control. But as Andrew Pickering reveals in this beguiling book, a much more lively and experimental strain of cybernetics can be traced from the 1940s to the present.The Cybernetic Brain explores a largely forgotten group of British thinkers, including Grey Walter, Ross Ashby, Gregory Bateson, R. D. Laing, Stafford Beer, and Gordon Pask, and their singular work in a dazzling array of fields. Psychiatry, engineering, management, politics, music, architecture, education, tantric yoga, the Beats, and the sixties counterc

  10. A Large Deformation Model for the Elastic Moduli of Two-dimensional Cellular Materials

    Institute of Scientific and Technical Information of China (English)

    HU Guoming; WAN Hui; ZHANG Youlin; BAO Wujun


    We developed a large deformation model for predicting the elastic moduli of two-dimensional cellular materials. This large deformation model was based on the large deflection of the inclined members of the cells of cellular materials. The deflection of the inclined member, the strain of the representative structure and the elastic moduli of two-dimensional cellular materials were expressed using incomplete elliptic integrals. The experimental results show that these elastic moduli are no longer constant at large deformation, but vary significantly with the strain. A comparison was made between this large deformation model and the small deformation model proposed by Gibson and Ashby.

  11. Lack of genotoxic potential of acetylated monoglyceride: An alternative plasticiser to phthalates

    DEFF Research Database (Denmark)

    Mortensen, Alicja; Wedebye, Eva Bay; Niemelä, Jay Russell;


    Purpose: With a yearly polymer production of more than 400 million tons, phthalates based on non sustainable petrochemical materials are the most used group of plasticisers. Their low biodegradability and endocrine activity suspected to affect reproductive ability of animals and humans caused...... substance and the substances in the training set of the model. The (Q)SAR's prediction was followed by in vitro testing using Salmonella/microsome assay (Ames test) with strains TA 98 and TA 100, with and without metabolic activation. Results: There were no warnings for genotoxic fragments (Ashby...


    Institute of Scientific and Technical Information of China (English)

    杨强; 杨卫


    The authors proposed a plausible explanation for the deviation of experimental data for sub-micron polycrystals from the Hall-Petch relation by in troducing the configuration entropy. The present paper extends the previous two dimensional analysis to the three-dimensional case. The statistical distribution of dislocation lengths within a spherical grain and the bow-out of dislocations are con sidered. According to Ashby's model, analyses are pursued for the statistically stored dislocations and geometrically necessary dislocations, respectively. It is confirmed that the configuration entropy model can predict the abnormal Hall-Petch depen dence for grain sizes in the sub-micron range.

  13. The Effect of Grain Size and Strain on the Tensile Flow Stress of Aluminium at Room Temperature

    DEFF Research Database (Denmark)

    Hansen, Niels


    Tensile-stress-strain data over a strain range from 0.2 to 30% were obtained at room temperature for 99.999 and 99.5% aluminium as a function of grain size. The yield stress-grain size relationship can be expressed by a Petch-Hall relation with approximately the same slope for the two materials. ...... stress-grain size relationship was analyzed in terms of matrix strengthening and grain boundary strengthening according to the dislocation concept of Ashby. At intermediate strains this approach gives a good description of the effect of strain, grain size and purity on the flow stress....

  14. Comment on "Frequency shifts in NIST Cs primary frequency standards due to transverse rf field gradients"

    CERN Document Server

    Gibble, Kurt


    We discuss the theoretical treatment of the microwave lensing frequency shift of the NIST-F1 and F2 atomic fountain clocks by Ashby et al. [Phy. Rev. A. 91, 033624 (2015)]. The shifts calculated by NIST are much smaller than the previously evaluated microwave lensing frequency shifts of other clocks contributing to International Atomic Time. We identify several fundamental problems in the NIST treatment and demonstrate that each significantly affects their results. We also show a smooth transition of microwave lensing frequency shifts to the photon recoil shift for large wave packets.

  15. Sancho Panza es aqueste [Grabación sonora


    La Grande Chapelle (Grupo musical); Recasens, Àngel; Lambea, Mariano; Josa, Lola; Recasens, Albert


    Duración: 3:30. Selección y adaptación (texto y música), Lola Josa (Universidad de Barcelona) y Mariano Lambea (Consejo Superior de Investigaciones Científicas). Intérpretes: La Grande Chapelle ; Cécile Kempenaers, soprano ; Kate Ashby, soprano ; Sytse Buwalda, contratenor ; Hervé Lamy, tenor. Director: Àngel Recasens. Fuente: Cancionero Musical de la Casa de Medinaceli (s.XVI). Productor ejecutivo, asesor musicológico y editor: Albert Recasens. Textos en español, inglés, francés y alemán....

  16. Matters of Gravity, the newsletter of the APS Topical Group on Gravitation, Spring 1997

    CERN Document Server

    Pullin, J


    Contents: News: April 1997 Joint APS/AAPT Meeting, by Beverly Berger TGG News, by Jim Isenberg Report from NSF, by David Berley We hear that..., by Jorge Pullin Research briefs: GR in GPS, by Neil Ashby What happens near the innermost stable circular orbit? by Doug Eardley Conference reports: Journees Relativistes 96, by D. Brill, M. Heusler, G. Lavrelashvili TAMA Workshop, by Peter Saulson Midwest gravity meeting, by Comer Duncan OMNI-1 Workshop by N.S. Magalhaes, W. F. Velloso Jr and O.D. Aguiar Chandra Symposium, by Robert Wald Penn State Meeting, by Lee Smolin Aspen Winter Conference, by Syd Meshkov

  17. Communication of Semantic Properties

    DEFF Research Database (Denmark)

    Lenau, Torben Anker; Boelskifte, Per


    a distinct character. For the technical properties there exists a well developed and commonly accepted terminology that can be utilised at product search and material selection (Ashby 1996). This is not the case for the semantic properties which are important for the outcome reflecting the product design...... processes. This working paper argues for the need for a commonly accepted terminology used to communicate semantic product properties. Designers and others involved in design processes are dependent of a sharp and clear verbal communication. Search facilities in computer programs for product and material...

  18. Differentiating adaptive and maladaptive perfectionism on the MMPI-2 and MIPS revised. (United States)

    Rice, Kenneth G; Stuart, Jennifer


    Although conceptualizations of perfectionism have emphasized adaptive as well as maladaptive expressions of the construct, how these different dimensions or types of perfectionists might be reflected in comprehensive personality assessment instruments is unknown. An initial sample of 267 university students completed the Minnesota Multiphasic Personality Inventory-2 (MMPI-2; Butcher, Dahlstrom, Graham, Tellegen, & Kaemmer, 2001), Millon Index of Personality Styles Revised (MIPS-R; Millon, 2004), and Almost Perfect Scale-Revised (Slaney, Mobley, Trippi, Ashby, & Johnson, 1996). Analyses indicated that dimensions and types of perfectionism were associated, in expected directions, with select scores on the MMPI-2 and MIPS-R.

  19. Influence of using nanoobjects as filler on functionality-based energy use of nanocomposites (United States)

    Roes, A. L.; Tabak, L. B.; Shen, L.; Nieuwlaar, E.; Patel, M. K.


    The goal of our study was to investigate the potential benefits of reinforcing polymer matrices with nanoobjects for structural applications by looking at both the mechanical properties and environmental impacts. For determining the mechanical properties, we applied the material indices defined by Ashby for stiffness and strength. For the calculation of environmental impacts, we applied the life cycle assessment methodology, focusing on non-renewable energy use (NREU). NREU has shown to be a good indicator also for other environmental impacts. We then divided the NREU by the appropriate Ashby index to obtain the `functionality-based NREU'. We studied 23 different nanocomposites, based on thermoplastic and thermosetting polymer matrices and organophilic montmorillonite, silica, carbon nanotubes (single-walled and multiwalled) and calcium carbonate as filler. For 17 of these, we saw a decrease of the functionality-based NREU with increasing filler content. We draw the conclusion that the use of nanoobjects as filler can have benefits from both an environmental point of view and with respect to mechanical properties.

  20. Screening and Preliminary Identification for a Strain of Nitrogen -Fixing Bacterium Producing PHB%一株产 PHB 固氮菌的筛选和初步鉴定

    Institute of Scientific and Technical Information of China (English)

    李贵正; 涂国全; 刘纪臣; 李新柱


    Eight nitrogen -fixing bacteria were isolated from the activated sludge from sewage farm of Kingenta by enriching culture and isolating in Ashby medium.Three strains producing PHB were obtained by Suda black staining.Strain N1 was regarded as the best one by the PHB diameter,content of PHB account for cell dry weight and the colony growth rate.Strain N1 was preliminary identified as Azotobacter chroococcum.%经 Ashby 培养基富集培养及平板分离,从金正大污水处理厂的活性污泥中分离到8株自生固氮菌。经苏丹黑染色初筛获得3株产 PHB 菌株。以菌株产生的 PHB 颗粒大小、PHB 占细胞干重的含量及菌落生长速度为指标,获得最佳菌株 N1。通过《伯杰氏细菌学鉴定手册》第九版初步鉴定此菌株为圆褐固氮菌(Azotobacter chroococcum)。

  1. Peak strength model of brittle rocks containing flaws%含裂纹缺陷脆性岩石的峰值强度模型

    Institute of Scientific and Technical Information of China (English)

    林鹏; 王仁坤; 黄凯珠; 周维垣


    在分析Ashby 和Hallam含缺陷脆性介质峰值强度理论模型基础上,对其进行修正,并用修正的理论模型研究单轴作用下,含裂纹缺陷花岗岩试样的裂纹萌生、扩展、贯通和相互作用等因素对峰值强度的影响规律.通过与物理试验和数值模拟结果对比分析发现: 修正后的Ashby-Hallam强度模型能定量地预测含缺陷岩石的峰值强度,以及定性分析峰值强度同裂纹缺陷密度和裂纹贯通密度的关系;含裂纹缺陷脆性岩体的峰值强度主要与贯通的裂纹数以及缺陷的分布和缺陷大小有关.

  2. Property predictions using microstructural modeling

    Energy Technology Data Exchange (ETDEWEB)

    Wang, K.G. [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, CII 9219, 110 8th Street, Troy, NY 12180-3590 (United States)]. E-mail:; Guo, Z. [Sente Software Ltd., Surrey Technology Centre, 40 Occam Road, Guildford GU2 7YG (United Kingdom); Sha, W. [Metals Research Group, School of Civil Engineering, Architecture and Planning, The Queen' s University of Belfast, Belfast BT7 1NN (United Kingdom); Glicksman, M.E. [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, CII 9219, 110 8th Street, Troy, NY 12180-3590 (United States); Rajan, K. [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, CII 9219, 110 8th Street, Troy, NY 12180-3590 (United States)


    Precipitation hardening in an Fe-12Ni-6Mn maraging steel during overaging is quantified. First, applying our recent kinetic model of coarsening [Phys. Rev. E, 69 (2004) 061507], and incorporating the Ashby-Orowan relationship, we link quantifiable aspects of the microstructures of these steels to their mechanical properties, including especially the hardness. Specifically, hardness measurements allow calculation of the precipitate size as a function of time and temperature through the Ashby-Orowan relationship. Second, calculated precipitate sizes and thermodynamic data determined with Thermo-Calc[copyright] are used with our recent kinetic coarsening model to extract diffusion coefficients during overaging from hardness measurements. Finally, employing more accurate diffusion parameters, we determined the hardness of these alloys independently from theory, and found agreement with experimental hardness data. Diffusion coefficients determined during overaging of these steels are notably higher than those found during the aging - an observation suggesting that precipitate growth during aging and precipitate coarsening during overaging are not controlled by the same diffusion mechanism.

  3. 冬枣早期落叶病致病菌分离鉴定及防治药剂筛选试验%Separation and Identification of Pathogen of the Leaf Cast Disease on Winter Jujube and Screening of Fungicides

    Institute of Scientific and Technical Information of China (English)

    郑秀社; 张庆国; 徐丽; 暴晓; 王红; 张澎; 宋家清


    [Objective] The research aimed to determine the pathogen caused by the leaf cast disease of winter jujube and screen effective fungicides. [Method] Disease samples showed typical symptom were collected and five representative strains were selected to determine morphology, cultural characters, staining reaction, physiological and biochemical reactions and pathogenicity of pathogen, compared with Xantflomonas campestris pv.malvacearum and Psedomonas syringae pv.tabaci. The antibacterial effects of 31 fungicides on the pathogen caused by the leaf cast disease of winter jujube were determined indoor. [Result] The result showed that the leaf cast disease of winter jujube caused by Xanthomonas campestris (Pammel) Dowson and Xanthomonas cepacia Burkhodor. In the field the leaf cast disease caused mainly by Xanthomonas campestris (Pammel) Dowson. The control effects of streptomycin sulfate, 72% streptomycin, neomycin and 50% mancozeh were best. The diameter of inhibition zone reached i.8- 4.8 cm with good transparency. [Conclusion] 4- 6 kinds of fungicides were selected to control the leaf cast disease of winter jujube, which used in the field control tests, demonstration and popularization.%【目的】为了明确引起冬枣早期落叶病的致病菌并选择有效的药剂进行防治。【方法】采集具有典型症状的病害标样,室内分离纯化后选取5个代表菌株,对病原细菌形态、培养性状、染色反应、生理生化反应和致病性等性状进行测定,并与棉花角斑病菌和烟草野火病菌进行比较、同时室内测定了31种杀菌剂对冬枣早期落叶病病菌的皿内抑菌效果;【结果】结果表明,甘蓝黑腐黄单胞菌和洋葱假单胞菌均能引起冬枣早期落叶病,田间以甘蓝黑腐黄单胞菌侵染为主。硫酸链霉素、72%农用链霉素、新植霉素、50%代森锰锌等4种药剂防治效果最好,抑菌圈直径为j.8~4.8cm,押菌斑透明程度好

  4. Surface temperatures and glassy state investigations in tribology, part 4 (United States)

    Bair, S. S.; Winer, W. O.


    Measurements were made of the limiting shear stress for two naphthenic oils of differing molecular weight and three blends of the lower molecular weight oil and polyalkylmethacrylate polymers of differing molecular weight. The two base oils reached the same limiting shear stress for the same temperature and pressure. This was also true for all the polymer solutions although the polymer reduced the limiting shear stress by about 15 percent. It is shown that limiting stress is more a function of material type than viscosity or molecular weight. A new falling body viscometer was constructed to operate to 230 C and 0.6 GPa. Another viscometer was constructed to extend the pressure range to 1.1 GPa. A concentrated contact simulator was developed which allows recording of the traction force while the slide-roll ratio is continuously varied and the rolling speed is maintained essentially constant by a single drive motor. The configuration is that of a crowned roller against a disk. Measurement of lubricant minimum film thickness of elliptical EHD contacts of various aspect ratios were made by optical interferometry. The data collected were used to evaluate the Hamrock and Dowson minimum film thickness model over a range of contract ellipticity ratio where the major axis of the contact ellipse was aligned both parallel and perpendicular to the direction of motion. A statistical analysis of the measured film thickness data showed that on the average the experimental data were 30 percent greater than the film thickness predicted by the model. Preliminary development of the application of a scanning infrared radiation system to a tribo-system was completed.

  5. Diagnóstico molecular de enfermedades sistémicas de la caña de azúcar en la Argentina: ajuste metodológico y aplicaciones Molecular diagnosis of sistemic sugarcane diseases in Argentina: methodology adjustment and applications

    Directory of Open Access Journals (Sweden)

    María P. Filippone

    Full Text Available Las enfermedades sistémicas representan uno de los principales factores que afectan la producción de caña de azúcar. El conocimiento del estado fitosanitario del cultivo y la identificación correcta de los fitopatógenos son claves para reducir las pérdidas por enfermedades. En este sentido, es fundamental contar con técnicas de diagnóstico sensibles, rápidas y fáciles de ejecutar, para realizar un diagnóstico preciso y precoz. A partir del año 2005, en la Estación Exper imental Agroindustrial Obispo Colombres se incorporó el diagnóstico molecular basado en la reacción en cadena de la polimerasa, para la detección específica de cuatro enfermedades sistémicas de la caña de azúcar: raquitismo de la caña soca (Leifsonia xyli sp. xyli, escaldadura de la hoja (Xanthomonas albilineans, mosaico de la caña de azúcar (Sugarcane mosaic virus, ScMV y síndrome de la hoja amarilla (Sugarcane yellow leaf virus, ScYLV. En este trabajo, se presenta la optimización metodológica del diagnóstico molecular y se compara su eficiencia con la de la técnica inmunoquímica ELISA. El método molecular mostró mayor sensibilidad para las enfermedades evaluadas, tanto bacterianas como virales. El establecimiento del diagnóstico molecular constituye un avance tecnológico de gran importancia para la industria azucarera regional, ya que no solo ayudará a disminuir la incidencia de dichas enfermedades, sino que también evitará el ingreso de otras nuevas al introducir germoplasma de caña de azúcar desde otras regiones.Systemic diseases represent one of the main factors affecting sugarcane production. The knowledge of crop sanitary conditions and the correct identification of phytopathogens are key factors to reduce losses caused by them. To diagnose diseases as early as possible is crucial, so techniques that are sensitive, fast, accurate and easy to use are essential. Since 2005, molecular diagnosis based on polymerase chain reaction has

  6. Dinámica de la brotación potencial de caña semilla micropropagada y termotratada de tres cultivares de caña de azúcar Potential germination dynamics of micropropagated and hot-water-treated seedcane of three sugarcane cultivars

    Directory of Open Access Journals (Sweden)

    Patricia A. Digonzelli


    Full Text Available Se comparó la dinámica de la brotación potencial (brotación en condiciones óptimas de humedad y temperatura de estacas uninodales de caña semilla saneada, obtenida por micropropagación y por termoterapia (inmersión en agua caliente 50ºC durante 2 h de tres cultivares (LCP 85-384, CP 65-357 y CP 48-103 y en tres edades (7, 10 y 12 meses. La semilla micropropagada e hidrotermotratada se encontraba libre de achaparramiento de la caña soca (Ratoon Stunting Disease, RSD (Leifsonia xyli subsp. xyli y escaldadura de la hoja (Xanthomonas albilineans. Las estacas se colocaron en una cámara de cría, en bandejas con arena lavada y esterilizada, a temperatura de 26 ± 2ºC, luz continua y control de humedad. El diseño experimental utilizado fue un factorial completamente aleatorizado (3x3x2, con dos repeticiones. Los factores fueron: edad (tres niveles, cultivar (tres niveles y origen de la semilla (dos niveles. Diariamente se contaron las yemas brotadas (clavo visible hasta la estabilización de la brotación. La dinámica de la brotación potencial se ajustó al modelo exponencial simple, función sigmoide simétrica, con R2 ≥ 0,97 y a partir del modelo se derivaron las variables deducidas: t50 y t90 (días al 50% y 90% de la emergencia máxima, porcentaje máximo de brotación, tasa media y tasa máxima de brotación potencial. La brotación en la semilla micropropagada presentó una mayor velocidad y una menor duración que en la termotratada. El porcentaje final varió entre el 80% y el 100%, en independencia del origen de la semilla.The potential germination dynamics (germination under optimal humidity and temperature conditions of healthy seedcane of three cultivars (LCP 85-384, CP 65-357 and CP 48-103 at three different ages (7, 10 and 12 months were compared, by studying one-joint billets of seedcane obtained through micropropagation and hot water treatment (inmersion into water heated at 50ºC, for 2 h. This micropropagated and hot

  7. Comparación de la calidad de semilla de caña de azúcar en el segundo corte según el método de saneamiento Assessment of first ratoon seedcane quality obtained through different methods

    Directory of Open Access Journals (Sweden)

    Patricia A. Digonzelli

    Full Text Available En Semilleros Registrados de caña azúcar de tres cultivares, provenientes de diferentes orígenes de saneamiento, se compararon los componentes de producción de caña semilla para la edad de soca 1 (segundo corte del semillero. La semilla estaba libre de RSD (Leifsonia xyli subsp. xyli y escaldadura de la hoja (Xanthomonas albilineans. El diseño experimental fue completamente aleatorizado, con cuatro repeticiones. Los tratamientos evaluados fueron: dos orígenes de la semilla, micropropagada e hidrotermotratada (50ºC, 2 h, y tres variedades (LCP 85-384, CP 65-357 y CP 48-103. Cada parcela experimental constaba de cinco surcos de 3 m y se evaluó la caña de los tres surcos centrales. En la cosecha del semillero, se contaron todos los tallos por parcela y se midió su altura hasta hoja +1. En una muestra de 36 tallos por parcela se determinó el peso, el diámetro en la parte media y el número de yemas por tallo. A partir de los datos obtenidos, se calculó el número de yemas por surco de 100 metros de longitud y la producción de caña por parcela. La caña semilla micropropagada presentó mayor altura y peso por tallo y una mayor producción de caña que la semilla termotratada. En cuanto al número de tallos, diámetro y número de yemas por tallo y por surco, no hubo diferencias significativas relacionadas al origen de la semilla. La variedad afectó significativamente a todos los componentes de la producción de caña semilla, a excepción de la altura de tallos, que solo dependió del origen de la simiente.Seedcane production components were assessed in first ratoon (cane from second cut from Registered Nurseries obtained through micropropagation and hot water treatment (50ºC, 2 h of LCP 85-384, CP 65-357 and CP 48-103 cultivars. Micropropagated and hot-water-treated seedcane was free from ratoon stunting disease (RSD (Leifsonia xyli subsp. xyli and leaf scald (Xanthomonas albilineans. A completely randomized factorial design (3x3x2

  8. Efecto de la época de plantación en la dinámica de la emergencia de caña semilla de alta calidad (termotratada y micropropagada de las variedades CP 65-357 y LCP 85-384 Effect of planting date on emergence dynamics of high quality CP 65-357 and LCP 85-384 seed cane (hot-water treated and micropropagated

    Directory of Open Access Journals (Sweden)

    Patricia A. Digonzelli


    Full Text Available Se evalúa el efecto de la época de plantación en la dinámica de la emergencia de caña semilla de alta calidad (micropropagada y termotratada de las variedades CP 65-357 y LCP 85-384, en condiciones de disponibilidad hídrica adecuada. La caña semilla micropropagada y termotratada (50ºC, 2 hs se plantó, con una densidad de 15 yemas/m, en tres épocas contrastantes: otoño, invierno y primavera. El material empleado estaba libre de escaldadura de la hoja (Xanthomonas albilineans y achaparramiento (Leifsonia xyli subsp. xyli. La época de plantación afectó todas las variables de la dinámica de la emergencia en las dos variedades y en ambos orígenes de la semilla. El origen afectó significativamente el inicio y la duración de la emergencia (t e y t50, pero no tuvo efecto en el porcentaje final ni en la tasa media de emergencia. La emergencia (% fue mayor en la plantación de octubre, que en las de mayo y agosto (59%, 35% y 45%, respectivamente. El te y el t50 fueron mayores en mayo que en agosto y octubre. La semilla micropropagada presentó, en general, valores de t e y t50 menores que la termotratada. La época de plantación fue el principal factor que afectó la dinámica de la emergencia de caña semilla de alta calidad de CP 65-357 y LCP 85-384. La variedad y el origen de la semilla afectaron significativamente, aunque en menor magnitud que la época de plantación, el inicio y la duración de la fase de emergencia.Planting date influence on emergence dynamics of high quality CP 65-357 and LCP 85-384 seed cane (hot-water treated and micropropagated, without humidity constraints, was evaluated. Material used was free from leaf scald disease (Xanthomonas albilineans and ratoon stunting disease (Leifsonia xyli subsp. xyli. Seed cane, micropropagated and hot-water treated (50ºC, 2 hours, was planted with a 15 buds/m density in three contrasting dates: autumn, winter and spring. The material was irrigated during the trial. Planting

  9. Producción de caña semilla en Semilleros Registrados provenientes de micropropagación y de hidrotermoterapia de tres cultivares de caña de azúcar Seedcane production in Registered Nurseries obtained through micropropagation and hot water treatment of three sugarcane cultivars

    Directory of Open Access Journals (Sweden)

    Patricia A. Digonzelli


    Full Text Available Se evaluaron los componentes de la producción de caña semilla en Semilleros Registrados de caña de azúcar provenientes de micropropagación e hidrotermoterapia (50ºC, 2 h, en tres variedades (LCP 85-384, CP 65-357 y CP 48-103 y tres épocas de plantación (mayo, agosto y octubre. La semilla micropropagada y la hidrotermotratada estaban libres de achaparramiento de la caña soca (Leifsonia xyli subsp. xyli o RSD, por sus siglas en inglés, y escaldadura de la hoja (Xanthomonas albilineans. El diseño experimental fue un factorial completamente aleatorizado 3x3x2, con tres repeticiones. Los factores fueron: época de plantación (tres niveles, variedad (tres niveles y origen de la semilla (dos niveles. Cada parcela constaba de cinco surcos de 3 metros, evaluando los tres surcos centrales. En la cosecha del semillero se contaron todos los tallos por parcela y se midió su altura hasta hoja TVD. En una muestra de 45 tallos por parcela se determinaron el peso y número de yemas por tallo. A partir de los datos obtenidos se calculó el número de yemas por surco de 100 metros de longitud y por hectárea. El origen de la caña semilla (micropropagada o hidrotermotratada afectó el número de tallos y la altura y número de yemas por tallo, por surco y por hectárea. La época de plantación y la variedad afectaron los componentes de la producción de caña semilla. La micropropagada presentó una mayor población, altura y número de yemas por tallo, permitiendo aumentar entre el 8% y 23% el área que es posible plantar a partir de una hectárea de Semillero Registrado. La magnitud de las diferencias entre la caña semilla micropropagada y termotratada varió según cultivares y época de plantación.Seedcane yield components in sugarcane Registered Nurseries obtained through micropropagation and hot water treatment (50ºC, 2 h were evaluated, considering three varieties (LCP 85-384, CP 65-357 and CP 48-103 and three plantation dates (May, August

  10. Epicoccum nigrum P16, a sugarcane endophyte, produces antifungal compounds and induces root growth.

    Directory of Open Access Journals (Sweden)

    Léia Cecilia de Lima Fávaro

    Full Text Available BACKGROUND: Sugarcane is one of the most important crops in Brazil, mainly because of its use in biofuel production. Recent studies have sought to determine the role of sugarcane endophytic microbial diversity in microorganism-plant interactions, and their biotechnological potential. Epicoccum nigrum is an important sugarcane endophytic fungus that has been associated with the biological control of phytopathogens, and the production of secondary metabolites. In spite of several studies carried out to define the better conditions to use E. nigrum in different crops, little is known about the establishment of an endophytic interaction, and its potential effects on plant physiology. METHODOLOGY/PRINCIPAL FINDINGS: We report an approach based on inoculation followed by re-isolation, molecular monitoring, microscopic analysis, plant growth responses to fungal colonization, and antimicrobial activity tests to study the basic aspects of the E. nigrum endophytic interaction with sugarcane, and the effects of colonization on plant physiology. The results indicate that E. nigrum was capable of increasing the root system biomass and producing compounds that inhibit the in vitro growth of sugarcane pathogens Fusarium verticillioides, Colletotrichum falcatum, Ceratocystis paradoxa, and Xanthomomas albilineans. In addition, E. nigrum preferentially colonizes the sugarcane surface and, occasionally, the endophytic environment. CONCLUSIONS/SIGNIFICANCE: Our work demonstrates that E. nigrum has great potential for sugarcane crop application because it is capable of increasing the root system biomass and controlling pathogens. The study of the basic aspects of the interaction of E. nigrum with sugarcane demonstrated the facultative endophytism of E. nigrum and its preference for the phylloplane environment, which should be considered in future studies of biocontrol using this species. In addition, this work contributes to the knowledge of the interaction of this

  11. On the history of Ludwig von Bertalanffy's "General Systemology", and on its relationship to cybernetics - part III: convergences and divergences (United States)

    Drack, Manfred; Pouvreau, David


    Bertalanffy's so-called "general system theory" (GST) and cybernetics were and are often confused: this calls for clarification. In this article, Bertalanffy's conceptions and ideas are compared with those developed in cybernetics in order to investigate the differences and convergences. Bertalanffy was concerned with first order cybernetics. Nonetheless, his perspectivist epistemology is also relevant with regard to developments in second order cybernetics, and the latter is therefore also considered to some extent. W. Ross Ashby's important role as mediator between GST and cybernetics is analysed. The respective basic epistemological approaches, scientific approaches and inherent world views are discussed. We underline the complementarity of cybernetic and "organismic" trends in systems research within the unitary hermeneutical framework of "general systemology".

  12. The Structure of Multidimensional Perfectionism: Support for a Bifactor Model With a Dominant General Factor. (United States)

    Smith, Martin M; Saklofske, Donald H


    Evidence suggests perfectionism is a multidimensional construct composed of 2 higher order factors: perfectionistic strivings and perfectionistic concerns. However, the substantial overlap between perfectionistic strivings and perfectionistic concerns is problematic, as are the unanswered questions regarding the structure of perfectionism following removal of common variance. This research addressed this through bifactor modeling. Three student samples (N = 742) completed Hewitt and Flett's ( 1991 ) Multidimensional Perfectionism Scale, Frost, Marten, Lahart, and Rosenblate's ( 1990 ) Multidimensional Perfectionism Scale, and Slaney, Rice, Mobley, Trippi, and Ashby's ( 2001 ) Almost Perfect Scale-Revised. Greater support was consistently found for the bifactor model, relative to the 2-factor model. Results suggest the bifactor model best represents the structure of perfectionism and provide preliminary support for the use of a general factor score. Researchers are cautioned that removal of general variance may render the reliability of specific factors (i.e., perfectionistic strivings and perfectionistic concerns) suspect.

  13. Combining Speed and Accuracy in Cognitive Psychology: Is the Inverse Efficiency Score (IES a Better Dependent Variable than the Mean Reaction Time (RT and the Percentage Of Errors (PE?

    Directory of Open Access Journals (Sweden)

    Raymond Bruyer


    Full Text Available Experiments in cognitive psychology usually return two dependent variables: the percentage of errors and the reaction time of the correct responses. Townsend and Ashby (1978, 1983 proposed the inverse efficiency score (IES as a way to combine both measures and, hence, to provide a better summary of the findings. In this article we examine the usefulness of IES by applying it to existing datasets. Although IES does give a better summary of the findings in some cases, mostly the variance of the measure is increased to such an extent that it becomes less interesting. Against our initial hopes, we have to conclude that it is not a good idea to limit the statistical analyses to IES without further checking the data.

  14. Mosca-Negra-dos-Citros: Características Gerais, Bioecologia e Métodos de Controle dessa Importante Praga Quarentenária da Citricultura Brasileira

    Directory of Open Access Journals (Sweden)

    Anderson Siva


    Abstract. Citrus blackfly, Aleurocanthus woglumi Ashby, is a serious pest of citrus culture and other economically important fruit crops. It is a present quarantine pest or A2 maximum alert restricting trades with other regions free of its presence. Since the first occurrence of the citrus blackfly in Belém in 2001 its dissemination was quickly to other States and regions of citrus production in Brazil. As an exotic pest, basic knowledge is scarce in order to establish the appropriate management to the insect in Brazil. Thus, the aim of the present study was to provide information about important aspects of A. woglumi, such as: history and geographical distribution, bioecology, host plants, appropriate control methods, among others, in order to provide subsidies for futures researches about the citrus blackfly in Brazil.

  15. Compression and Energy Absorption Properties of Gradual Porous Aluminum Alloy%梯度孔径多孔铝合金的压缩及吸能性能

    Institute of Scientific and Technical Information of China (English)

    黄可; 何思渊; 何德坪



  16. Brittle dynamic damage due to earthquake rupture (United States)

    Bhat, Harsha; Thomas, Marion


    The micromechanical damage mechanics formulated by Ashby and Sammis, 1990, and generalized by Deshpande and Evans 2008 has been extended to allow for a more generalized stress state and to incorporate an experimentally motivated new crack growth (damage evolution) law that is valid over a wide range of loading rates. This law is sensitive to both the crack tip stress field and its time derivative. Incorporating this feature produces additional strain-rate sensitivity in the constitutive response. The model is also experimentally verified by predicting the failure strength of Dionysus-Pentelicon marble over wide range of strain rates. We then implement this constitutive response to understand the role of dynamic brittle off-fault damage on earthquake ruptures. We show that off-fault damage plays an important role in asymmetry of rupture propagation and is a source of high-frequency ground motion in the near source region.

  17. Dynamic Homeostasis in Packet Switching Networks

    CERN Document Server

    Oka, Mizuki; Ikegami, Takashi


    In this study, we investigate the adaptation and robustness of a packet switching network (PSN), the fundamental architecture of the Internet. We claim that the adaptation introduced by a transmission control protocol (TCP) congestion control mechanism is interpretable as the self-organization of multiple attractors and stability to switch from one attractor to another. To discuss this argument quantitatively, we study the adaptation of the Internet by simulating a PSN using ns-2. Our hypothesis is that the robustness and fragility of the Internet can be attributed to the inherent dynamics of the PSN feedback mechanism called the congestion window size, or \\textit{cwnd}. By varying the data input into the PSN system, we investigate the possible self-organization of attractors in cwnd temporal dynamics and discuss the adaptability and robustness of PSNs. The present study provides an example of Ashby's Law of Requisite Variety in action.


    Institute of Scientific and Technical Information of China (English)



    关于HIP(热等静压)工艺的模型化,已进行了30多年.开发HIP工艺模型的目的,在于使HIP工艺最佳化,节约材料,减少HIP坯料或制品的切削加工量,降低生产成本,尽快生产出近终形或成品零件.本文评述了开发HIP工艺模型的3条途径,概述了4种HIP工艺模型化的现状与效果,最后介绍了对Ashby HIP6.0模型的一个试验验证.

  19. Preparation and characterization of porous titanium using space-holder technique

    Institute of Scientific and Technical Information of China (English)

    NIU Wenjuan; BAI Chenguang; QIU Guibao; WANG Qiang; WEN Liangying; CHEN Dengfu; DONG Lingyan


    Titanium-based porous materials can be used in structural applications and medical implants because of their excellent mechanical properties at elevated temperatures, good corrosion resistance and wonderful biocompatibility. However, most of the methods used to produce the po-rous metal can only give limited porosity and uncontrollable pore morphologies. In the present study, a newly developed method of powder metallurgy using the space-holder technique was used to fabricate porous titanium with controllable porosity. The morphological features and mechanical properties of the products were fully investigated. The results show that the porosity is in the range of 55%-75%, and the mean pore size, with an average sphericity of~0.72, is 600 μm The plateau stresses vary between 10 MPa and 35 MPa. As predicted by the Gibson-Ashby model, the plateau stress decreases with increasing porosity.

  20. 由大学遗传环境论看美国研究型大学科研管理%On Scientific Research Management in American Re-search Universities from the Perspective of the Theory of University's Genetic Environment

    Institute of Scientific and Technical Information of China (English)


      阿什比曾在其著作中提出大学遗传环境论,该理论通过生物学视角和跨学科方法来研究高等教育领域的相关问题。本文由该理论出发,分析美国研究型大学在科研管理方面的具体情况,并探究原因,获得启示。%The theory of university's genetic environment was raised by Eric Ashby. This theory played a significant role for its unique research method. Now we use it to analyze the scientific research management of the research university in America and find some enlightenment.

  1. Measurement of the Microwave Lensing shift in NIST-F1 and NIST-F2 (United States)

    Jefferts, S. R.; Heavner, T. P.; Barlow, S. E.; Ashby, N.


    With several Primary Frequency Standards (PFS) across the world demonstrating systematic fractional frequency uncertainties on order of 1 x 10-16, it is crucial to accurately measure or model even small frequency shifts that could affect the ultimate PFS uncertainty, and thus ultimately impact the rate of Coordinated Universal Time (UTC) which relies on precision PFS measurements. Recently there has been controversy about the physical causes and size of PFS frequency shifts due to microwave lensing effects. We present here the first measurements of microwave lensing frequency shifts in the PFS NIST-F1 and NIST-F2. The measured frequency shifts agree well with the recent theory of Ashby et al [1].

  2. Application of powder densification models to the consolidation processing of composites (United States)

    Wadley, H. N. G.; Elzey, D. M.


    Unidirectional fiber reinforced metal matrix composite tapes (containing a single layer of parallel fibers) can now be produced by plasma deposition. These tapes can be stacked and subjected to a thermomechanical treatment that results in a fully dense near net shape component. The mechanisms by which this consolidation step occurs are explored, and models to predict the effect of different thermomechanical conditions (during consolidation) upon the kinetics of densification are developed. The approach is based upon a methodology developed by Ashby and others for the simpler problem of HIP of spherical powders. The complex problem is devided into six, much simpler, subproblems, and then their predicted contributions are added to densification. The initial problem decomposition is to treat the two extreme geometries encountered (contact deformation occurring between foils and shrinkage of isolated, internal pores). Deformation of these two geometries is modelled for plastic, power law creep and diffusional flow. The results are reported in the form of a densification map.

  3. Characterization of 316L Steel Cellular Dodecahedron Structures Produced by Selective Laser Melting

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    Konda Gokuldoss Prashanth


    Full Text Available The compression behavior of different 316L steel cellular dodecahedron structures with different density values were studied. The 316L steel structures produced using the selective laser melting process has four different geometries: single unit cells with and without the addition of base plates beneath and on top, and sandwich structures with multiple unit cells with different unit cell sizes. The relation between the relative compressive strength and the relative density was compared using different Gibson-Ashby models and with other published reports. The different aspects of the deformation and the mechanical properties were evaluated and the deformation at distinct loading levels was recorded. Finite element method (FEM simulations were carried out with the defined structures and the mechanical testing results were compared. The calculated theory, simulation estimation, and the observed experimental results are in good agreement.

  4. Mathematical modeling of localized melting around graphite nodules during laser surface hardening of austempered ductile iron (United States)

    Roy, A.; Manna, I.


    An attempt has been made to mathematically predict the optimum conditions of laser surface hardening (LSH) of austempered ductile iron (ADI) that can ensure a predominantly martensitic microstructure and preclude partial/complete dissolution of graphite nodules in the laser hardened zone during laser irradiation. The exercise involves prediction of the thermal profile (using the Ashby and Easterling model), and consequently, the carbon diffusion profile around the graphite nodules at different depths from the surface for the given conditions of LSH. Microstructural investigations have been carried out by optical and scanning electron microscopy to study the morphology, shape and width of the partially/completely melted graphite nodules as a function of the LSH parameters. Finally, the predicted maximum width of the melted zone around the graphite nodules is compared with the relevant experimental data to validate the proposed model.

  5. Resonance Phenomena in Goupillaud-type Media (United States)


    α1)(1 + α2), the tungsten -lead-aluminum configuration with α1 ≈ 5.828 and α2 ≈ 0.952 has the same value of χ2 ≈ 13.33 as the lead-aluminum-copper...material)-nickel- bronze configuration with α1 ≈ 2.27, α2 ≈ 0.698 and α3 = 1/α1 ≈ .44, has almost the same value of χ3 = 8 and Γ3 = 0, as the homogeneous...Ashby (45)) are as follows: • Aluminum alloy: E = 70 GPa and ρ = 2, 500 kg/m3, • Brass: E = 20 GPa and ρ = 984.19 kg/m3, • Bronze : E = 50 GPa and ρ = 7

  6. Development of a constitutive model for the plastic deformation and creep of copper and its use in the estimate of the creep life of the copper canister

    Energy Technology Data Exchange (ETDEWEB)

    Pettersson, Kjell [Matsafe AB, Stockholm (Sweden)


    A previously developed model for the plastic deformation and creep of copper (included as an Appendix to the present report) has been used as the basis for a discussion on the possibility of brittle creep fracture of the copper canister during long term storage of nuclear waste. Reported creep tests on oxygen free (OF) copper have demonstrated that copper can have an extremely low creep ductility. However with the addition of about 50 ppm phosphorus to the copper it appears as if the creep brittleness problem is avoided and that type of copper (OFP) has consequently been chosen as the canister material. It is shown in the report that the experiments performed on OFP copper does not exclude the possibility of creep brittleness of OFP copper in the very long term. The plasticity and creep model has been used to estimate creep life under conditions of intergranular creep cracking according to a model formulated by Cocks and Ashby. The estimated life times widely exceed the design life of the canister. However the observations of creep brittleness in OF copper indicate that the Cocks-Ashby model probably does not apply to the OF copper. Thus additional calculations have been done with the plasticity and creep model in order to estimate stress as a function of time for the probably most severe loading case of the canister with regard to creep failure, an earth quake shear. Despite the fact that the stress in the canister will remain at the 100 MPa level for thousands of years after an earth quake the low temperature, about 50 deg C or less, will make the solid state diffusion process assumed to control the brittle cracking process, too slow to lead to any significant brittle creep cracking in the canister.

  7. Analyses of the Classical Model for Porous Materials%多孔材料模型分析

    Institute of Scientific and Technical Information of China (English)

    刘培生; 夏凤金; 罗军


    New developments are ceaselessly gained for the preparation, the application and the property study of porous materials. As to the theories about the structure and properties of porous materials, the famous classical model-Gibson-Ashby model has been being commonly endorsed in the field of porous materials all over the world, and is the theoretical foundation widespreadly applied by numerous investigators to their relative researches up to now. Some supplementary thinking and analyses are made for the shortages in this model in the present paper, and it is found that some shortages can even break the completivity originally shown by this model. Based on the summery about these problems, another new model is introduced which can make up the shortcomings existed in Gibson-Ashby model.%多孔泡沫材料的制备、应用和性能研究均不断取得新的进展.在关于多孔材料结构和性能方面的理论中,著名的经典性模型--Gibson-Ashby模型一直受到国际同行的普遍认同,迄今仍然是众多研究者在研究工作中广泛应用的理论基础.对该模型尚存在的若干不足和问题进行了一些补充思考和分析,发现其中有些缺陷甚至可以打破该模型原来表现出来的"完满性".在总结陈述这些问题的基础上,引荐了可以克服或弥补上述模型不足的另一个模型.

  8. Characterization of free nitrogen fixing bacteria of the genus Azotobacter in organic vegetable-grown Colombian soils

    Directory of Open Access Journals (Sweden)

    Diego Javier Jiménez


    Full Text Available With the purpose of isolating and characterizing free nitrogen fixing bacteria (FNFB of the genus Azotobacter, soil samples were collected randomly from different vegetable organic cultures with neutral pH in different zones of Boyacá-Colombia. Isolations were done in selective free nitrogen Ashby-Sucrose agar obtaining a recovery of 40%. Twenty four isolates were evaluated for colony and cellular morphology, pigment production and metabolic activities. Molecular characterization was carried out using amplified ribosomal DNA restriction analysis (ARDRA. After digestion of 16S rDNA Y1-Y3 PCR products (1487pb with AluI, HpaII and RsaI endonucleases, a polymorphism of 16% was obtained. Cluster analysis showed three main groups based on DNA fingerprints. Comparison between ribotypes generated by isolates and in silico restriction of 16S rDNA partial sequences with same restriction enzymes was done with Gen Workbench v.2.2.4 software. Nevertheless, Y1-Y2 PCR products were analysed using BLASTn. Isolate C5T from tomato (Lycopersicon esculentum grown soils presented the same in silico restriction patterns with A. chroococcum (AY353708 and 99% of similarity with the same sequence. Isolate C5CO from cauliflower (Brassica oleracea var. botrytis grown soils showed black pigmentation in Ashby-Benzoate agar and high similarity (91% with A. nigricans (AB175651 sequence. In this work we demonstrated the utility of molecular techniques and bioinformatics tools as a support to conventional techniques in characterization of the genus Azotobacter from vegetable-grown soils.

  9. Caracterización de cepas nativas de Azotobacter spp. y su efecto en el desarrollo de Lycopersicon esculentum Mill. “tomate” en Lambayeque

    Directory of Open Access Journals (Sweden)

    Cynthia Escobar


    Full Text Available El objetivo de la presente investigación fue caracterizar y determinar el efecto de cepas nativas de Azotobacter spp. en el desarrollo vegetativo de Lycopersicon esculentum Mill. “tomate”, como una alternativa al uso indiscriminado de fertilizantes químicos. Se tomaron muestras de raíces y suelo rizosférico de hortalizas con las que se realizaron diluciones (10-4 en caldo Ashby-Sacarosa y se incubaron a 30 ºC hasta observar un color amarillo, turbidez y película superficial. El género Azotobacter se identificó en agar mineral sin nitrógeno y Ashby-Benzoato, obteniéndose 96 cepas con una producción de 7.10 a 57.99 mgL-1 de ácido indolacético, 0.13 a 1.64 mgL-1 de nitrógeno fijado como amonio y hasta 1.61 % de eficiencia en la solubilización de roca fosfórica de Bayóvar. Se obtuvo una suspensión celular (108 de cada una de las cuatro cepas con los mayores valores y se inocularon independientemente y en consorcio, así como una combinación con 50 % de urea-100 % de roca fosfórica, en la rizósfera de tomate cv. Río Grande, en un diseño experimental completamente aleatorio. Todas las cepas nativas incrementaron la altura, volumen radicular, materia seca total, parte aérea y radicular frente al testigo absoluto.

  10. The Neighbor Switching Mechanism of Superplastic Deformation (United States)

    Sherwood, David John

    At one time the notion that crystal plasticity resulted from the simultaneous motion of lattice planes over one another was entertained. This idea was displaced by the concept that relative atomic motions occur sequentially when dislocations move through the crystal. Similarly, McLean suggested that grains switch neighbors sequentially in a polycrystalline material undergoing superplastic flow. Morral and Ashby observed that the neighbor switching reactions in a froth occurred at irregular cells, and that these irregularities were associated with dislocations in the cellular array. They introduced cellular dislocation glide as a model for superplastic flow, and suggested that if the concentration of these defects required to make the froth flow increased with the flow stress, then the froth would have a non-Newtonian viscosity, like many superplastic materials. Cahn and Padawer pointed out that cellular dislocation climb was used as a model for grain growth by Hillert; this process results in the elimination of cells from the froth. Sato, Kuribayashi and Horiuchi used cellular dislocation climb to model both grain motion and the deformation-enhanced grain growth which can accompany superplastic flow. Here, the neighbor switching mechanism of superplastic deformation is developed as a topic in dislocation theory. The compatibility theory of dislocations is developed at an introductory level with exterior calculus. "Compatibility" of a cellular array corresponds to statements, a la Rivier, about the distribution of edges amongst the cells. The theory of dislocation motion, or crystal plasticity, is also developed with exterior calculus. Morral and Ashby's constitutive relationship for superplastic flow is analyzed and two models for deformation-enhanced grain growth are developed. The constitutive relationship and grain growth kinetics for superplastic flow are illustrated by modelling the behavior exhibited by single phase (Sn-1% Bi) and quasi -single phase (7475 Al

  11. Density dependent mechanical properties and structures of a freeze dried biopharmaceutical excipient--sucrose. (United States)

    Devi, Sharmila; Williams, Daryl R


    Knowledge of the mechanical behaviour of freeze dried biopharmaceutical products is essential for designing of products with physical robustness that will not to crack, crumble or collapse during processing or transportation. The compressive mechanical deformation behaviour for freeze-dried sucrose cakes has been experimentally studied from a relative density (ρf/ρs) of 0.01-0.30 using a novel in-vial indentation test. Cakes exhibited more open like structures at lower densities and more closed structures at higher densities with some faces being present at all densities, as confirmed by SEM. The reduced elastic modulus Ef/Es=0.0044(ρf/ρs)(1) for all cake densities, indicating that face stretching was the dominant deformation mode assuming Gibson and Ashby's closed cell model. This linear scaling for the reduced elastic modulus is in line with various theoretical treatments based on tetrakaidecahedral cells and other experimental studies. Consistently, the wall thickness to cell diameter ratio scaled ρf/ρs with a power constant of 1.05. The maximum crushing stress was given by σmax=3800(ρf/ρs)(1.48) which agrees with a strut bending failure stress, assuming Gibson and Ashby's open cell model. Overall, the freeze dried cakes behaved as neither classic closed cell nor open cell materials, with their compressive elastic moduli reflecting a closed cell elastic response whilst their failure stresses reflecting an open cell failure mode. It was concluded that the mechanical response of freeze dried cellular materials depends upon their complex cellular structures and morphologies, and they cannot be rationalised using simple limiting case models of open or closed cell solids.

  12. Analysis on High Temperature Strength and Sealing Behavior of U-type Seal in Steam Turbine Valves%汽轮机进汽阀U型密封高温强度与密封性能分析

    Institute of Scientific and Technical Information of China (English)


      U型密封因其优越的密封性能而被广泛应用在超超临界汽轮机进汽阀门中。随着运行参数(温度,压力)不断提升, U 型密封承受的蠕变越发严重。为了研究 U 型密封在高参数运行条件下的蠕变强度与密封性能,引用经过时间硬化修正的 Norton-Bailay 蠕变本构方程和基于孔洞长大理论的多轴蠕变模型,分析计算了汽轮机进气阀U型密封2×105 h工作时域内接触面位置、接触应力和蠕变多轴度因子的变化规律。结果表明:随蠕变时间增加,U型密封的接触应力下降明显;U型密封的关键部位受到较大多轴应力影响,并产生较大的 Cocks-Ashby 蠕变等效应变,试验结果与预测结果一致。%U-type seal has been widely used in the inlet valves of ultra-supercritical steam turbines due to its superior sealing performance. However, the U-type seal bears greater creep deformation with the increase of the operational parameters (T, P). In order to investigate the creep strength and sealing performance of the U-type seal, the modified time-hardening Norton-Bailay constitutive equation and multiaxial cavity growth model were employed in the calculation. Furthermore, the variation of contact position, contact stress and multiaxial factor of U-type seal of steam turbine valve were analyzed under 0.2 million creep hours. The results illustrate that the contact stress of U-type seal significantly reduces with the creep hours increases. Some key areas of U-type seal suffer great multi-axial state of stress, and then huge Cock-Ashby equivalent strain is produced. The experimental result is consistent with predicted result.

  13. Effect of tempering temperature on microstructure and properties of X120 pipeline steel%回火工艺对X120管线钢组织与性能的影响

    Institute of Scientific and Technical Information of China (English)

    唐兴昌; 康永林; 薄艳艳


    利用扫描电镜(SEM)、透射电镜(TEM)等实验方法,研究了回火温度500~650℃对X120管线钢组织和性能的影响。运用Ashby-Orowan修正模型等强化理论分析了X120管线钢回火工艺的强化机理。结果表明:回火温度对屈服强度和抗拉强度均有较大影响,回火后实验钢屈服强度分别在回火温度为550℃和600℃出现两个峰值,抗拉强度在600℃时出现峰值,伸长率略有升高,屈强比升高。分析认为:回火过程中实验钢性能的变化是由析出强化、位错强化、固溶强化等强化机理共同作用造成的。%The correlation among tempering temperature,microstructure and mechanical property of the X120 pipeline steel was investigated.Microstructure of the rolles steel tempered at different temperatures(500-650 ℃) was observed by scanning electronic microscopy(SEM) and transmission electronic microscopy(TEM).The strengthening mechanism of X120 pipeline steel was studied by using a corrected Ashby-Orowan model.The results indicate that significant influence of tempering temperature on yield strength and tensile strength of the tempered X120 pipeline steel is observed.The supelrior mechanical properties are obtained for the steel tempered at 600 ℃ for 2 h.It is argued that the strengthening mechanism of the steel during tempering is the combination of precipitation strengthening,solid-solution strengthening and dislocation strengthening.

  14. Resiliencia, tamaño de grano y microestructura generada en la ZAC de los aceros HSLA 450 EMZ soldados bajo un proceso SMAW

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    González, R.


    Full Text Available In this paper several features of the HAZ between the weld metal and the parent metal, after the heat cycle produced by a SMAW process in 450 N/mm2 HSLA steels are analysed, taking into consideration the temperatures reached in the HAZ as from Rosenthal's equation. The aspects under examination are: grain morphology by means of micrographs obtained with the Scannig Electron Microscopy to check the bands that control the grain size due to the microalloyings of the designed steel, taking into account the temperatures reached and the cooling rate in each of the HAZ regions; fracture toughness, checked by means of CTOD testing; hardness grain size determined by the Ashby and Esterling procedure[1] and based on the values obtained with the Heyn method[2] , ratio between stable growth and heat input; CTOD values which are found to be satisfactory under the welding conditions with a heat input of 1.6 Kj/mm.

    Tras el ciclo térmico producido por un proceso de soldadura manual con electrodo revestido (SMAW, en los aceros HSLA de 450 N/ mm2 y, considerando las temperaturas alcanzadas en la ZAC según la ecuación de Rosenthal, se analizan los siguientes aspectos en esta zona (ZAC, entre el metal de soldadura y el metal base: la morfología del grano mediante micrografías obtenidas en el microscopio electrónico de barrido, comprobando las barreras que pinzan el grano debido a los microaleantes de este acero de diseño, teniendo en cuenta las temperaturas alcanzadas y la velocidad de enfriamiento en cada una de las regiones de la ZAC; la tenacidad a la fractura mediante los ensayos de CTOD; la dureza; el tamaño de grano, mediante el procedimiento de Ashby y Esterling[1] y basado en los valores obtenidos por el método de Heyn[2]; la proporcionalidad entre el crecimiento estable y la energía calorífica aportada; los valores de CTOD, satisfactorios en las condiciones de soldeo con

  15. Aislamientos de cepas fijadoras de nitrógeno y solubilizadoras de fósforo en un suelo alfisol venezolano Isolation of nitrogen-fixing and phosporus-solubilizing strains in alfisol soils of Venezuela

    Directory of Open Access Journals (Sweden)

    Learsy Padron


    Full Text Available Para evaluar el potencial de los suelos del Valle Medio del Río Yaracuy para la producción de biofertilizantes, se aislaron cepas fijadoras de nitrógeno (FNVL y solubilizadoras de fósforo (SF en suelos sometidos a diferentes condiciones de manejos. Para ello muestra rizosferica en los usos caña de azúcar (Sacharum oficcinarum, maíz (Zea mayz L., lechoza (Carica papaya, pasto (Brachiaria decumbens, además de un área bajo bosque natural, las muestras fueron tomadas en abril de 2010, las bacterias FNVL y SF fueron aisladas usando medio Ashby y Pikoskaya respectivamente, las principales propiedades químicas y físicas del suelo fueron evaluadas, para establecer su relación con el desarrollo de las cepas. Los resultados muestran que las FN se desarrollaron mejor en los usos pasto y caña de azúcar con 20 y 10 cepas respectivamente, lo que indica que las cepas FNVL se desarrollaron mejor en aquellos manejos con bajo contenido de materia orgánica o manejo intensivo, el mayor numero de bacterias SF se observaron en aquellos manejos con mayor contenido de fósforo (lechoza con 13 colonias, o en usos con adecuadas condiciones físicas para el desarrollo microorganismos (bosque, con 10 colonias.In order to evaluate the potential of soils in the Middle Valley of Yaracuy River in Venezuela for the production of biofertilizers, nitrogen fixed strains (FBN and phosphorus-solubilizing strains (SF were isolated in soils subjected to different management conditions. For this, rizhosferic samples in six different land uses were taken in April, 2010. Sugarcane (Sacharum officinarum, maize (Zea mayz L., pawpaw (Carica papaya, grass (Brachiaria decumbens and a forest area were sampled. Bacteria FNVL and SF were isolated using Ashby and Pikoskaya, respectively. Chemical and physical properties were evaluated in all soils to determine the relationship between them and the development of the strains. Results showed that Fn developed better in grass and

  16. Characterization of cellular titanium for biomedical applications (United States)

    Hrabe, Nikolas Wilson

    By controlling structural features (relative density, pore size, strut size) of cellular titanium (also known as porous titanium), the mechanical properties can be optimized to reduce the effects of stress shielding currently observed in load-bearing bone replacement implants. Thermal gravimetric analysis of a sacrificial scaffold system lead to important processing modifications in an attempt to meet chemistry requirements for surgical grade titanium not met in previous work. Despite these modifications chemistry did not meet requirements for carbon, nitrogen, or oxygen. Commercially pure titanium (CPTi) porous structures were made over a range of relative densities using laser engineered net shaping (LENS). From monotonic compression tests, yield strength and elastic modulus in the range of bone were achieved but did not scale with relative density as predicted by the Gibson-Ashby analytical model. Compression-compression fatigue resistance was high, as no failures were observed for test stresses up to 133% yield strength, which is thought to be influenced by the dense exterior shell of the samples. Structures were also fabricated over a range of relative densities using selective electron beam melting (SEBM or EBM), and structural, mechanical, and in-vitro properties were measured for three materials (as-built Ti-6A1-4V, Ti-6A1-4V after hot isostatic pressing (HIPing), and as-built CPTi). For structures of all three materials, yield strength and elastic modulus was within the range for bone. Numerical modeling results suggested cell shape and sintered particles on strut surfaces affect the scaling of elastic modulus with relative density and lead to the observed difference from the Gibson-Ashby model. Normalized fatigue strengths at 106 cycles ranged from 0.150.25 for as-built Ti-6A1-4V structures, which is lower than expected. Results for HIPed Ti-6A1-4V structures and CPTi structures suggest that stress concentrations from closed porosity within struts as well

  17. Comportamiento productivo y fitosanitario de la nueva variedad de caña de azúcar (Saccharum spp. TUC 95-37 en Tucumán, R. Argentina Productivity and disease tolerance of TUC 95-37, a new sugarcane (Saccharum spp. variety in Tucumán, Argentina

    Directory of Open Access Journals (Sweden)

    Ernesto R. Chavanne


    Full Text Available En este trabajo se presenta el comportamiento productivo y fitosanitario del nuevo cultivar de caña de azúcar (Saccharum spp. TUC 95-37, obtenido y seleccionado por el Programa de Mejoramiento Genético de la Caña de Azúcar de la Estación Experimental Agroindustrial Obispo Colombres (Tucumán, R. Argentina. La información que se presenta proviene de 24 cosechas realizadas en ensayos con 18 genotipos, implantados de acuerdo a un diseño experimental de bloques completamente aleatorizados con tres repeticiones. Los ensayos se replicaron en seis localidades de Tucumán y fueron evaluados en cuatro edades de corte (caña planta, soca 1, soca 2 y soca 3 entre los años 2002 y 2005. Las variables toneladas de caña/ha y de azúcar/ha y rendimiento fabril porciento se evaluaron en mayo. Para cada variable, edad y localidad se realizaron análisis de la varianza y pruebas de comparación de medias. También se aplicó la metodología de GGE biplot como herramienta gráfica, para identificar genotipos superiores y estables frente a distintos ambientes de expresión. Se evaluó además el comportamiento fitosanitario de TUC 95-37. Los resultados indicaron que la nueva variedad evidenció un comportamiento productivo similar al de LCP 85-384 en la mayoría de las edades de corte y localidades evaluadas. En caña planta, el nuevo cultivar fue el genotipo más productivo, presentando además una amplia adaptación a diferentes ambientes. En soca 1 y 2, TUC 95-37 resultó segunda en orden de mérito, siendo estable en las diferentes localidades. En soca 3, la nueva variedad evidenció una menor estabilidad frente al ambiente. Con respecto al comportamiento fitosanitario, TUC 95-37 se comportó como moderadasmente resistente a roya marrón (Puccinia melanocephala, a escaldadura de la hoja (Xanthomonas albilineans y a carbón (Sporisorium scitamineum. Se mostró moderadamente susceptible al mosaico (Sugarcane mosaic virus y a estría roja (Acidovorax

  18. Environmental health impacts: occurrence, exposure and significance, Lancaster University, UK, 9-10 September 2003. (United States)

    Martin, Francis L; Semple, Kirk T


    Speakers: John Ashby (Syngenta CTL, UK), Peter A. Behnisch (Eurofins GfA, Germany), Paul L. Carmichael (Unilever Colworth, UK), Curtis C.Harris (National Cancer Institute, USA), Kevin C. Jones (Lancaster University, UK), Andreas Kortenkamp (School of Pharmacy, London, UK), Caroline J. Langdon (Reading University, UK), Anthony M. Lynch (GlaxoSmithKline, UK), Francis L. Martin (Lancaster University, UK), Trevor J. McMillan (Lancaster University, UK), David H. Phillips (Institute of Cancer Research, UK), Huw J. Ricketts (University of Cardiff, UK), Michael N. Routledge (University of Leeds, UK), J. Thomas Sanderson (Utrecht University, The Netherlands) and Kirk T. Semple (Lancaster University, UK) The effects of many environmental exposures to either single contaminants or to mixtures still remain to be properly assessed in ecotoxicological and human toxicological settings. Such assessments need to be carried out using relevant biological assays. On a mechanistic basis, future studies need to be able to extrapolate exposure to disease risk. It is envisaged that such an approach would lead to the development of appropriate strategies to either reduce exposures or to initiate preventative measures in susceptible individuals or populations. To mark the opening of a new Institute, the Lancaster Environmental Centre, an environmental health workshop was held over 2 days (9-10 September 2003) at Lancaster University, UK. The fate, behaviour and movement of chemicals in the environment, together with environmental exposures and human health, biomarkers of such exposures, hormone-like compounds and appropriate genetic toxicology methodologies, were discussed.

  19. Modeling and additive manufacturing of bio-inspired composites with tunable fracture mechanical properties. (United States)

    Dimas, Leon S; Buehler, Markus J


    Flaws, imperfections and cracks are ubiquitous in material systems and are commonly the catalysts of catastrophic material failure. As stresses and strains tend to concentrate around cracks and imperfections, structures tend to fail far before large regions of material have ever been subjected to significant loading. Therefore, a major challenge in material design is to engineer systems that perform on par with pristine structures despite the presence of imperfections. In this work we integrate knowledge of biological systems with computational modeling and state of the art additive manufacturing to synthesize advanced composites with tunable fracture mechanical properties. Supported by extensive mesoscale computer simulations, we demonstrate the design and manufacturing of composites that exhibit deformation mechanisms characteristic of pristine systems, featuring flaw-tolerant properties. We analyze the results by directly comparing strain fields for the synthesized composites, obtained through digital image correlation (DIC), and the computationally tested composites. Moreover, we plot Ashby diagrams for the range of simulated and experimental composites. Our findings show good agreement between simulation and experiment, confirming that the proposed mechanisms have a significant potential for vastly improving the fracture response of composite materials. We elucidate the role of stiffness ratio variations of composite constituents as an important feature in determining the composite properties. Moreover, our work validates the predictive ability of our models, presenting them as useful tools for guiding further material design. This work enables the tailored design and manufacturing of composites assembled from inferior building blocks, that obtain optimal combinations of stiffness and toughness.

  20. Mechanical Properties of a Metal Powder-Loaded Polyurethane Foam

    Energy Technology Data Exchange (ETDEWEB)

    C. L. Neuschwanger; L. L. Whinnery; S. H. Goods


    Quasi-static compression tests have been performed on polyurethane foam specimens. The modulus of the foam exhibited a power-law dependence with respect to density of the form: E* {proportional_to} {rho}*{sup n}, where n = 1.7. The modulus data is well described by a simple geometric model (attributed to the work of Gibson and Ashby) for closed-cell foam in which the stiffness of the foam is governed by the flexure of the cell struts and cell walls. The compressive strength of the foam is also found to follow a power-law behavior with respect to foam density. In this instance, Euler buckling is used to rationalize the density dependence. The modulus of the polyurethane foam was modified by addition of a gas atomized, spherical aluminum powder. Additions of 30 and 50 weight percent of the powder significantly increased the foam modulus. However, there were only slight increases in modulus with 5 and 10 weight percent additions of the metal powder. Strength was also slightly increased at high loading fractions of powder. This increase in modulus and strength could be predicted by combining the above geometric model with a well-known model describing the effect on modulus of a rigid dispersoid in a compliant matrix.

  1. A combined analysis of the Frost Multidimensional Perfectionism Scale (FMPS), Child and Adolescent Perfectionism Scale (CAPS), and Almost Perfect Scale-Revised (APS-R): Different perfectionist profiles in adolescent high school students. (United States)

    Sironic, Amanda; Reeve, Robert A


    To investigate differences and similarities in the dimensional constructs of the Frost Multidimensional Perfectionism Scale (FMPS; Frost, Marten, Lahart, & Rosenblate, 1990), Child and Adolescent Perfectionism Scale (CAPS; Flett, Hewitt, Boucher, Davidson, & Munro, 2000), and Almost Perfect Scale-Revised (APS-R; Slaney, Rice, Mobley, Trippi, & Ashby, 2001), 938 high school students completed the 3 perfectionism questionnaires, as well as the Depression Anxiety Stress Scales (DASS; Lovibond & Lovibond, 1995). Preliminary analyses revealed commonly observed factor structures for each perfectionism questionnaire. Exploratory factor analysis of item responses from the questionnaires (combined) yielded a 4-factor solution (factors were labeled High Personal Standards, Concerns, Doubts and Discrepancy, Externally Motivated Perfectionism, and Organization and Order). A latent class analysis of individuals' mean ratings on each of the 4 factors yielded a 6-class solution. Three of the 6 classes represented perfectionist subgroups (labeled adaptive perfectionist, externally motivated maladaptive perfectionist, and mixed maladaptive perfectionist), and 3 represented nonperfectionist subgroups (labeled nonperfectionist A, nonperfectionist B, and order and organization nonperfectionist). Each of the 6 subgroups was meaningfully associated with the DASS. Findings showed that 3 out of 10 students were classified as maladaptive perfectionists, and maladaptive perfectionists were more prevalent than adaptive perfectionists. In sum, it is evident that combined ratings from the FMPS, CAPS, and APS-R offer a meaningful characterization of perfectionism.

  2. INVESTIGATION OF THE INFLUENCE OF SUBSYSTEMS OF DIFFERENT LEVELS OF THE HIERARCHY ON EMERGENT PROPERTIES OF THE SYSTEM IN GENERAL WITH THE USE OF THE ASC-ANALYSIS AND "EIDOS" INTELLECTUAL SYSTEM (microstructure of the system as a factor in the management of its macro properties Исследование влияния подсистем различных уровней иерархии на эмерджентные свойства системы в целом с применением АСК-анализа и интеллектуальной системы "Эйдос" (микроструктура системы как фактор управления ее макросвойствами

    Directory of Open Access Journals (Sweden)

    Lutsenko Y. V.


    Full Text Available The article, on a simple numerical example, deals with the application of the automated system-cognitive analysis (ASC-analysis and its software tools - intellectual systems "Eidos" for the detection and investigation of determination of emergent macro preferences of systems in their composition and hierarchical structure, i.e. the sub-systems of various complexity levels (levels of the hierarchy. The article briefly discusses some of the methodological issues of creation and application of formal models in scientific knowledge. The system generalization of the principle of William Ross Ashby about the necessary diversity on the basis of the system of generalization of the theory of sets and systems theory, information, generalized formulation of the principle of Galileo-Einstein, the hypothesis about its relationship with the theorem of Emmy Noether are offered; and also there is a hypothesis "About the dependence of the force and direction of the relations between the basic elements of the system and its emergent properties as a whole, on the level of hierarchy in the system"

  3. Mechanical properties and failure behavior of unidirectional porous ceramics (United States)

    Seuba, Jordi; Deville, Sylvain; Guizard, Christian; Stevenson, Adam J.


    We show that the honeycomb out-of-plane model derived by Gibson and Ashby can be applied to describe the compressive behavior of unidirectional porous materials. Ice-templating allowed us to process samples with accurate control over pore volume, size, and morphology. These samples allowed us to evaluate the effect of this microstructural variations on the compressive strength in a porosity range of 45-80%. The maximum strength of 286 MPa was achieved in the least porous ice-templated sample (P(%) = 49.9), with the smallest pore size (3 μm). We found that the out-of-plane model only holds when buckling is the dominant failure mode, as should be expected. Furthermore, we controlled total pore volume by adjusting solids loading and sintering temperature. This strategy allows us to independently control macroporosity and densification of walls, and the compressive strength of ice-templated materials is exclusively dependent on total pore volume.

  4. Effects of 4 Fungicides on Control of Banana Leaf Spot Diseases%4种药剂防治香蕉叶斑病效果比较

    Institute of Scientific and Technical Information of China (English)

    谢圣华; 王泰吉


    用25%敌力脱乳油、25%顷止乳油、25%富力库水乳剂和43%大生富悬浮剂4种药剂进行香蕉叶斑病[Cercospora musae Zimm、Cordana musae(Zimm)Hohn、Helminthosporiumtorulosum(Syd.)Ashby]防治试验.结果表明:25%敌力脱乳油、25%顷止乳油和25%富力库水乳剂3种新型药剂对香蕉叶斑病的防效均较传统药剂43%大生富悬浮剂的防效高,持效期也较长;3种新型药剂中,25%敌力脱乳油的防效和持效性均表现最好,最高防效达84.80%,药后21 d防效仍达77.57%;4种药剂防治香蕉叶斑病的施药间隔期,25%敌力脱乳油为20~25 d,25%顷止乳油为12~15 d,25%富力库水乳剂为15~20 d,43%大生富悬浮剂为7~10 d.

  5. Direct observations of damage during unconfined brittle failure of Carrara marble (United States)

    Tal, Yuval; Evans, Brian; Mok, Ulrich


    To observe and quantify the production of microfracturing from initial yield to failure, we deformed Carrara marble samples in uniaxial compression at 20, 105, and 180°C and continuously observed a region of about 1 mm2 on an exposed face with a long-working distance microscope. Using image processing and microscale strain-mapping techniques, we measured local strains over a length scale of tens of micrometers. By treating the images with various filters, we identified linear damage features, as well as the magnitude of localized strain and the mode of deformation, i.e., shear versus normal deformation. In general, shear deformation is more prevalent after initial yielding, while tensile deformation dominates closer to peak stress. Independent measurements of both stress and microcrack density at different stages of each experiment provide a unique opportunity to explicitly compare the data with damage models. The model of Ashby and Sammis (1990) significantly underestimated the damage that the rock could sustain before peak stress, perhaps owing to the influence of weak grain boundaries on the damage production. In these samples, microcracks tended to form near boundaries before yield stress. During strain hardening, the damage parameters increased rapidly as longer microcracks grew along the boundaries and finally transected grains as loading neared peak stress. The microcrack density can be empirically related to the reduction of Young's modulus; stiffness ratios decay exponentially with increasing microcrack density for T ≤ 105°C.

  6. Characterization of native strains of Azotobacter spp. and its effect on growth of Lycopersicon esculentum Mill. “tomato” in Lambayeque

    Directory of Open Access Journals (Sweden)

    Cynthia Escobar


    Full Text Available The objective of this research was characterize and determine the effect of native strains of Azotobacter spp. on the vegetative growth of Lycopersicon esculentum Mill. "Tomato" as an alternative to the indiscriminate use of chemical fertilizers. Samples were taken from roots and rhizosphere soil of vegetables from which dilutions (10-4 in Ashbysucrose broth and incubated at 30 ° C to observe a yellow color, turbidity and surface film. The genus Azotobacter was identified in mineral agar without nitrogen and Ashby-benzoate, obtaining 96 strains with a yield of 7.10 to 57.99 mgL-1 indoleacetic acid, 0.13 to 1.64 mgL-1 of fixed nitrogen as ammonium and up to 1.61% efficiency in the solubilization of phosphate Bayovar rock. It obtained a cell suspension (10 8 of each of the four strains with the highest values and inoculated independently and in consortium, as well as a combination with 50% urea-100 % phosphate rock in the rhizosphere of Rio Grande tomato, in a completely randomized design. The entire native strains increased height, root volume, total dry matter, shoot and root, compared with absolute control.

  7. Effect of pressure on the strength of olivine at room temperature (United States)

    Proietti, Arnaud; Bystricky, Misha; Guignard, Jérémy; Béjina, Frédéric; Crichton, Wilson


    A fine grained fully-dense olivine aggregate was deformed in a D-DIA press at room temperature and pressures ranging from 3.5 to 6.8 GPa, at constant strain rates between 6 ×10-6 and 2.2 ×10-5 s-1. A weighted non-linear least square fit of a dataset including our results and data from other high-pressure studies to a low-temperature plasticity flow law yields a Peierls stress σP0 = 7.4 (0.5) GPa and an activation energy E∗ = 232 (60) kJ.mol-1. The dependence of the Peierls stress to pressure, σP = σP0 (1 + 0.09 P) , appears to be larger than the value predicted by the formulation proposed by Frost and Ashby (1982). With such a dependence, the activation volume is very small (V* = 1.6 (1.7) cm3.mol-1). Extrapolation to natural conditions yields a viscosity of ~1023 -1024 Pa.s for a cold subducting slab at depths of 50-100 km.

  8. MicrOstructural Changes of Cu-Ni-Si AllOy during Aging

    Institute of Scientific and Technical Information of China (English)

    Qiming DONG; Dongmei ZHAO; Ping LIU; Buxi KANG; Jinliang HUANG


    Age hardening in Cu-3.2Ni-0.75Si (wt pct) and Cu-1.0Ni-0.25Si (wt pct) alloys from 723 to 823 K is studied. After an incubation period strengthening appears which is due to precipitates in the Cu-1.0Ni-0.25Si (wt pct) alloy. On other hand animmediate increase of the yield strength characterizes the aging of the alloy. This is followed by the regions of constant yield strength and further by a peak. The microstructure of the alloy was studied by, means of transmission electron microscope (TEM) and X-ray diffraction (XRD). Spinodal decomposition takes place followed by nucleation of the ordering coherent (Cu,Ni)3Si particles, further precipitation annealing coherent δ-Ni2Si nucleated within the (Cu,Ni)3Si particle. Any change of the yield strength can be described by an adequate change of the structure in the sample. The nature of the aging curves with a"plateau" is discussed. The formulas of Ashby and Labusch can be used to explain the precipitation.

  9. Thermal stability of interface voids in Cu grain boundaries with molecular dynamic simulations (United States)

    Xydou, A.; Parviainen, S.; Aicheler, M.; Djurabekova, F.


    By means of molecular dynamic simulations, the stability of cylindrical voids is examined with respect to the diffusion bonding procedure. To do this, the effect of grain boundaries between the grains of different crystallographic orientations on the void closing time was studied at high temperatures from 0.7 up to 0.94 of the bulk melting temperature ({{T}\\text{m}} ). The diameter of the voids varied from 3.5 to 6.5 nm. A thermal instability occurring at high temperatures at the surface of the void placed in a grain boundary triggered the eventual closure of the void at all examined temperatures. The closing time has an exponential dependence on the examined temperature values. A model based on the defect diffusion theory is developed to predict the closing time for voids of macroscopic size. The diffusion coefficient within the grain boundaries is found to be overall higher than the diffusion coefficient in the region around the void surface. The activation energy for the diffusion in the grain boundary is calculated based on molecular dynamic simulations. This value agrees well with the experimental given in the Ashby maps for the creep in copper via Coble GB diffusion.

  10. The Determining Role of Finish Cooling Temperature on the Microstructural Evolution and Precipitation Behavior in an Nb-V-Ti Microalloyed Steel in the Context of Newly Developed Ultrafast Cooling (United States)

    Li, Xiaolin; Wang, Zhaodong; Deng, Xiangtao; Wang, Guodong; Misra, R. D. K.


    We have studied here the impact of finish cooling temperature on the microstructural evolution and precipitation behavior in Nb-V-Ti microalloyed steel through thermo-mechanical simulation in the context of newly developed ultrafast cooling system. The microstructural evolution was studied in terms of morphology and crystallography of precipitates using high-resolution transmission electron microscopy. At finish cooling temperature of 933 K and 893 K (660 °C and 620 °C), the microstructure primarily consisted of polygonal ferrite, together with a small amount of wedge-shaped acicular ferrite and lamellar pearlite, while, at 853 K and 813 K (580 °C and 540 °C), the microstructure consisted of lath bainite with fine interlath cementite and granular bainite with martensite/austenite (M/A) constituent. In all the finish cooling temperatures studied, the near-spherical precipitates of size range ~2 to 15 nm were randomly dispersed in ferrite and bainite matrix. The carbide precipitates were identified as (Nb,V)C with NaCl-type crystal structure. With a decrease in the finish cooling temperature, the size of the precipitates was decreased, while the number density first increased with a peak at 893 K (620 °C) and then decreased. Using Ashby-Orowan model, the contribution of the precipitation strengthening to yield strength was ~149 MPa at the finish cooling temperature of 893 K (620 °C).

  11. Scaling of compression strength in disordered solids: metallic foams

    Directory of Open Access Journals (Sweden)

    J. Kováčik


    Full Text Available The scaling of compression strength with porosity for aluminium foams was investigated. The Al 99.96, AlMg1Si0.6 and AlSi11Mg0.6 foams of various porosity, sample size with and without surface skin were tested in compression. It was observed that the compression strength of aluminium foams scales near the percolation threshold with Tf ≈ 1.9 - 2.0 almost independently on the matrix alloy, sample size and presence of surface skin. The difference of the obtained values of Tf to the theoretical estimate of Tf = 2.64 ± 0.3 by Arbabi and Sahimi and to Ashby estimate of 1.5 was explained using an analogy with the Daoud and Coniglio approach to the scaling of the free energy of sol-gel transition. It leads to the finding that, there are two different universality classes for the critical exponent Tf: when the stretching forces dominate Tf = f = 2.1, respectively when bending forces prevail Tf = .d = 2.64 seems to be valid. Another possibility is the validity of relation Tf ≤ f which varies only according to the universality class of modulus of elasticity in foam.

  12. 含Nb-Ti低碳钢的析出与细晶强化效应研究%Study on Precipitation and Fine Grain Strengthening Effects of Low Carbon Steel with Nb-Ti

    Institute of Scientific and Technical Information of China (English)

    李德强; 叶其斌; 周成; 严玲


    采用控轧控冷(TMCP)工艺制备的0.013%Nb-0.013%Ti钢和C-Mn钢性能对比显示,添加微量Nb-Ti明显提高了钢的强度和冲击韧性,原因是微量Nb-Ti细化了铁素体晶粒并得到更高体积分数的弥散分布(Nb,Ti)(C,N)析出颗粒.用Hall-Petch晶粒尺寸强化和Ashby-Orowan弥散强化模型计算铁素体晶粒尺寸、析出颗粒尺寸和体积分数等微观组织变量对强度的量化贡献,结果表明,Nb -Ti钢的主要强化机理为细晶强化和弥散强化,而降低韧脆转变温度的主要机理是晶粒细化和微合金碳氮化物析出降低了钢中的自由氮含量.

  13. Assessing historical empathy through simulation – How do Finnish teacher students achieve contextual historical empathy?

    Directory of Open Access Journals (Sweden)

    Jukka Rantala


    Full Text Available There has been a great deal of international debate about introducing historical empathy as the focus in teaching history. However, as it is, the contents of the concept have been included in the curricula in many countries. Nevertheless, practising stepping into the shoes of a person from a previous era is still in its infancy in schools in many locations – Finland included. This article discusses Finnish class teacher students' understanding of historical empathy. The article is based on a study where 360 class teacher students played a game simulating the Cuban Missile Crisis. Their task was to assume the roles of the superpower leaders and make decisions on the basis of these roles. The simulation showed that a majority of the student teachers are able to attain a level of contextual historical empathy. They were able to empathize with the historical context in question and make such decisions that would have been possible for the historical actors. Some of the playing groups on the other hand, referred to their current knowledge and attitudes, which, according to Ashby and Lee's empathy classification, shows lower-level empathy. The study corroborates previous research results concerning great discrepancies in the understanding of empathy prevalent within one age group. Moreover, the study raises the question of how historical empathy should be handled in teaching if many future teachers have difficulties in understanding it.

  14. Materials selection for a transport packaging of Mo-99

    Energy Technology Data Exchange (ETDEWEB)

    Hara, Debora H.S.; Lucchesi, Raquel F.; Mancini, Victor A.; Rossi, Jesualdo L., E-mail: [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Fiore, Marina [Universidade de Sao Paulo (USP), SP (Brazil). Departamento de Engenharia Metalurgica e de Materiais. Escola Politecnica


    The radiopharmaceuticals are radioactive isotopes used in nuclear medicine for more accurate diagnosis and treatment of diseases or dysfunctions. Currently, the most important radionuclide for the preparation of radiopharmaceuticals for diagnostic purposes is technetium-99m ({sup 99m}Tc), a product of the radioactive decay of molybdenum-99 (Mo-99). The aim of this work was the materials selection that can enable the manufacture of a package for Mo-99 transport with the aid of CES EduPack program and the methodology developed by Ashby. The ESTAR program was used to check the occurrence of Bremsstrahlung and the XCOM program was used to calculate the attenuation coefficient of gamma radiation from some of the selected materials for the shield; after, the thickness required for radiation shielding was calculated. From the results, the materials selected as potential candidates for the manufacture of the shielding were the tungsten alloys. Related to the thermal insulation and the impact protection, woods, plywoods and particle boards stand out. With regard to internal and external coatings, the selected materials focus on groups of steels and nickel alloys. (author)

  15. The Influence of Pore Size on the Indentation Behavior of Metallic Nanoporous Materials: A Molecular Dynamics Study

    Directory of Open Access Journals (Sweden)

    Daniel Esqué-de los Ojos


    Full Text Available In general, the influence of pore size is not considered when determining the Young’s modulus of nanoporous materials. Here, we demonstrate that the pore size needs to be taken into account to properly assess the mechanical properties of these materials. Molecular dynamics simulations of spherical indentation experiments on single crystalline nanoporous Cu have been undertaken in systems with: (i a constant degree of porosity and variable pore diameter; and (ii a constant pore diameter and variable porosity degree. The classical Gibson and Ashby expression relating Young’s modulus with the relative density of the nanoporous metal is modified to include the influence of the pore size. The simulations reveal that, for a fixed porosity degree, the mechanical behavior of materials with smaller pores differs more significantly from the behavior of the bulk, fully dense counterpart. This effect is ascribed to the increase of the overall surface area as the pore size is reduced, together with the reduced coordination number of the atoms located at the pores edges.

  16. Porosity and cell size control in alumina foam preparation by thermo-foaming of powder dispersions in molten sucrose

    Directory of Open Access Journals (Sweden)

    Sujith Vijayan


    Full Text Available The foaming characteristics of alumina powder dispersions in molten sucrose have been studied as a function of alumina powder to sucrose weight ratio (WA/S and foaming temperature. The increase in foaming temperature significantly decreases the foaming and foam setting time and increases the foam volume due to an increase in the rate of OH condensation as well as a decrease in the viscosity of the dispersion. Nevertheless, the foam collapses beyond a critical foaming temperature, which depends on the WA/S. The sintering shrinkage depends mainly on the WA/S and marginally on the foaming temperature. The porosity (83.4–94.6 vol.% and cell size (0.55–1.6 mm increase with an increase in foaming temperature (120–170 °C and a decrease in WA/S (0.8–1.6. The drastic decrease in compressive strength and modulus beyond a WA/S of 1.2 is due to the pores generated on the cell walls and struts as a result of particle agglomeration. Gibson and Ashby plots show large deviation with respect to the model constants ‘C’ and ‘n’, especially at higher alumina powder to sucrose weight ratios.

  17. Mechanisms-based viscoplasticity: Theoretical approach and experimental validation for steel 304L (United States)

    Zubelewicz, Aleksander; Oliferuk, Wiera


    We propose a mechanisms-based viscoplasticity approach for metals and alloys. First, we derive a stochastic model for thermally-activated motion of dislocations and, then, introduce power-law flow rules. The overall plastic deformation includes local plastic slip events taken with an appropriate weight assigned to each angle of the plane misorientation from the direction of maximum shear stress. As deformation progresses, the material experiences successive reorganizations of the slip systems. The microstructural evolution causes that a portion of energy expended on plastic deformation is dissipated and the rest is stored in the defect structures. We show that the reorganizations are stable in a homogeneously deformed material. The concept is tested for steel 304L, where we reproduce experimentally obtained stress-strain responses, we construct the Frost-Ashby deformation map and predict the rate of the energy storage. The storage is assessed in terms of synchronized measurements of temperature and displacement distributions on the specimen surface during tensile loading.

  18. Metodología mixta de selección de materiales aplicada en la escogencia del material para un dedo de pinza de sujeción de un manipulador industrial

    Directory of Open Access Journals (Sweden)

    Royman J. López Beltrán


    Full Text Available El diseño mecánico implica muchas fases, siendo una de las más importantes la selección de un material óptimo para lograr un alto rendimiento en el componente diseñado. Para mejorar la fase de selección del material se han desarrollado muchas herramientas avanzadas. Actualmente se pueden encontrar programas que contienen extensas bases de datos con las principales propiedades del material, tales como el Cambridge Material Selector. Sin embargo, hay algunas propiedades que no tienen suficiente documentación en estos programas. Por ejemplo, existen limitaciones para obtener los valores de propiedades como la resistencia a la fluencia en compresión. Para estos eventos sería muy importante investigar sobre nuevas metodologías de selección, que pueden estar referenciadas en otras, para ejecutar una fase de selección de materiales eficiente y rápida. En este trabajo se desarrolla una metodología mixta de selección de materiales. Basándose en una combinación del método de selección de materiales Ashby y del cálculo experimental de propiedades mecánicas para soportar la escogencia, se presentan los resultados del proceso de selección aplicado a un dedo de una pinza de sujeción de un manipulador industrial

  19. Investigation of Macroscopic Brittle Creep Failure Caused by Microcrack Growth Under Step Loading and Unloading in Rocks (United States)

    Li, Xiaozhao; Shao, Zhushan


    The growth of subcritical cracks plays an important role in the creep of brittle rock. The stress path has a great influence on creep properties. A micromechanics-based model is presented to study the effect of the stress path on creep properties. The microcrack model of Ashby and Sammis, Charles' Law, and a new micro-macro relation are employed in our model. This new micro-macro relation is proposed by using the correlation between the micromechanical and macroscopic definition of damage. A stress path function is also introduced by the relationship between stress and time. Theoretical expressions of the stress-strain relationship and creep behavior are derived. The effects of confining pressure on the stress-strain relationship are studied. Crack initiation stress and peak stress are achieved under different confining pressures. The applied constant stress that could cause creep behavior is predicted. Creep properties are studied under the step loading of axial stress or the unloading of confining pressure. Rationality of the micromechanics-based model is verified by the experimental results of Jinping marble. Furthermore, the effects of model parameters and the unloading rate of confining pressure on creep behavior are analyzed. The coupling effect of step axial stress and confining pressure on creep failure is also discussed. The results provide implications on the deformation behavior and time-delayed rockburst mechanism caused by microcrack growth on surrounding rocks during deep underground excavations.

  20. 鄂西河谷地区柑桔黑刺粉虱灾变规律及应急控制技术

    Institute of Scientific and Technical Information of China (English)

    张国宝; 李银姣


    柑橘黑刺粉虱(Aleurocanthus woglumi Ashby)是国际贸易双边协定中涉及限定性的有害生物,自1995年以后上升为主要害虫,而且诱发严重的煤烟病,给生产造成损失很大.1998年以后,我们对该虫的灾变规律、控制技术进行了研究,结果表明,柑橘黑刺粉虱在鄂西河谷地区1年发生4代,越冬期虫态单一;通过试验,黑刺粉虱的最佳防治时期为:秋、冬、春连旱年份第1代在4月中旬至5月中旬,暖冬年份2月中旬至3月中旬防治越冬代效果较好;同时还试验筛选出了3个防治黑刺粉虱的农药配方,通过推广应用,取得了很好的经济效益和社会效益.

  1. Producción de un biofertilizante a partir de un aislamiento de Azotobacter nigricans obtenido en un cultivo de Stevia rebaudiana Bert

    Directory of Open Access Journals (Sweden)

    Daniel Borda-Molina


    Full Text Available Bio-fertilizer production from an isolate of Azotobacter nigricans obtained from a plantation of Stevia rebaudiana Bert. Objective.To isolate nitrogen fixing bacteria to be used in a fertilization regime of an organic agriculture program. Materials and methods. Theisolation of nitrogen fixing bacteria was done in an Ashby-benzoate medium from soil of a Stevia rebaudiana plantation. Isolates identifiedas Azotobacter nigricans were evaluated by their growth kinetics and the strain with the fastest growth was used for the production of abiofertilizer by discontinuous fermentation. The preliminary evaluation of the biofertilizer was done by its inoculation into t hree ridges ofa plantation of S. rebaudiana and yield determination was based upon biomass production and glycoside concentration. Results. Twoisolates (A5 and A6 were identified as A. nigricans based on their phenotypic and genotypic characterization. Isolate A5 was selected forpreparing the biofertilizer because it showed a better stability, pigmentation, a faster growth rate (0.1405 h-1 exponential phase of 18 hoursand an average IAA production of 38.4 mg/ml after 150 hours. The bio-fertilizer was obtained in milk medium with a cell concentration of4x1012 CFU/ml. Conclusions. The preliminary field evaluation showed a positive correlation between the increase of the glycosideconcentration in the leaves of S. rebaudiana and a higher production of biomass in response to the bio-fertilizer application.

  2. 剑麻根际联合固氮菌的分离及固氮活性测定%Isolation of Endophytic Diazotrophic Bacteria from Sisal and Determination of Their Nitrogenase Activity

    Institute of Scientific and Technical Information of China (English)

    陈河龙; 李庆洋; 易克贤; 高建明; 郑金龙; 刘巧莲; 张世清


    通过选用NFM、CCM、Ashby及改良的Dobereiner培养基,利用气相色谱仪(GC)对海南省昌江县、广西扶绥县和广东雷州市三地剑麻种植基地的剑麻根际联合固氮菌进行分离、纯化及利用乙炔还原法进行固氮活性测定,获得50株具有固氮活性的菌株,其固氮酶活性最高的菌株是ASN004,固氮酶活性为1 765.659 0 nmol/(mL·h),具有开发利用的潜力.%The associative nitrogen fixation bacteria in sisal rhizosphere, sampled from Changjiang County in Hainan Province, Fusui County in Guangxi Zhuang Autonomous Region and Leizhou City in Guangdong Province, were isolated and purified by Gas Chromatography on the NFM, CCM, Ashby and modified Dobereiner medium. And their nitrogen -fixing activity was measured by acetylene reduction method. The result indicated that, 50 bacterial strains had nitrogen -fixing activity. And a bacterial strain No. ASN004 with the highest nitrogenase activity of 1765.6590 nmol/(mL·h) was found and it had good exploitation potential.

  3. Differential effects of dopamine-directed treatments on cognition

    Directory of Open Access Journals (Sweden)

    Ashby FG


    Full Text Available F Gregory Ashby, Vivian V Valentin, Stella S von Meer Department of Psychological and Brain Sciences, University of California, Santa Barbara, CA, USA Abstract: Dopamine, a prominent neuromodulator, is implicated in many neuropsychiatric disorders. It has wide-ranging effects on both cortical and subcortical brain regions and on many types of cognitive tasks that rely on a variety of different learning and memory systems. As neuroscience and behavioral evidence for the existence of multiple memory systems and their corresponding neural networks accumulated, so did the notion that dopamine’s role is markedly different depending on which memory system is engaged. As a result, dopamine-directed treatments will have different effects on different types of cognitive behaviors. To predict what these effects will be, it is critical to understand: which memory system is mediating the behavior; the neural basis of the mediating memory system; the nature of the dopamine projections into that system; and the time course of dopamine after its release into the relevant brain regions. Consideration of these questions leads to different predictions for how changes in brain dopamine levels will affect automatic behaviors and behaviors mediated by declarative, procedural, and perceptual representation memory systems. Keywords: dopamine, cognition, memory systems, learning

  4. Mechanical properties and characteristics of nanometer-sized precipitates in hot-rolled low-carbon ferritic steel

    Institute of Scientific and Technical Information of China (English)

    Xiao-pei Wang; Ai-min Zhao; Zheng-zhi Zhao; Yao Huang; Liang Li; Qing He


    The microstructures and properties of hot-rolled low-carbon ferritic steel have been investigated by optical microscopy, field-emission scanning electron microscopy, transmission electron microscopy, and tensile tests after isothermal transformation from 600°C to 700°C for 60 min. It is found that the strength of the steel decreases with the increment of isothermal temperature, whereas the hole expan-sion ratio and the fraction of high-angle grain boundaries increase. A large amount of nanometer-sized carbides were homogeneously distrib-uted throughout the material, and fine (Ti, Mo)C precipitates have a significant precipitation strengthening effect on the ferrite phase because of their high density. The nanometer-sized carbides have a lattice parameter of 0.411-0.431 nm. After isothermal transformation at 650°C for 60 min, the ferrite phase can be strengthened above 300 MPa by precipitation strengthening according to the Ashby-Orowan mechanism.

  5. Trial-by-trial identification of categorization strategy using iterative decision-bound modeling. (United States)

    Hélie, Sébastien; Turner, Benjamin O; Crossley, Matthew J; Ell, Shawn W; Ashby, F Gregory


    Identifying the strategy that participants use in laboratory experiments is crucial in interpreting the results of behavioral experiments. This article introduces a new modeling procedure called iterative decision-bound modeling (iDBM), which iteratively fits decision-bound models to the trial-by-trial responses generated from single participants in perceptual categorization experiments. The goals of iDBM are to identify: (1) all response strategies used by a participant, (2) changes in response strategy, and (3) the trial number at which each change occurs. The new method is validated by testing its ability to identify the response strategies used in noisy simulated data. The benchmark simulation results show that iDBM is able to detect and identify strategy switches during an experiment and accurately estimate the trial number at which the strategy change occurs in low to moderate noise conditions. The new method is then used to reanalyze data from Ell and Ashby (2006). Applying iDBM revealed that increasing category overlap in an information-integration category learning task increased the proportion of participants who abandoned explicit rules, and reduced the number of training trials needed to abandon rules in favor of a procedural strategy. Finally, we discuss new research questions made possible through iDBM.

  6. 变形机理图的研究进展及发展趋势%Development and Prospect for Deformation Mechanism Map

    Institute of Scientific and Technical Information of China (English)

    周舸; 曹富荣; 丁桦


    变形机理图又称为塑性变形的相图,它对材料变形过程的预报对于材料成形科学基础研究具有重要的意义.文中分别对Ashby、Langdon-Mohamed、Ruano-Wadsworth-Sherby、含位错数量的R-W-S变形机理图的构建方法、使用条件及特点进行了介绍.为变形机理图在实际生产中的应用提供了理论基础.%Deformation mechanism map, I.e. Plastic deformation map, is effective to predict the material deformation during processing, which is very important for basic research on material processing. The constructing method, applying conditions and characteristics for the four deformation mechanism maps are introduced, for example, Ashby, Langdon-Mohamed, Ruano-Wadsworth-Sherby and dislocation R-W-S, respectively. The deformation mechanism map is the basic theory for application on production.

  7. Efecto del uso del suelo sobre rizobacterias fosfatosolubizadoras y diazotroficas en el distrito de riego del río zulia,norte de santander (colombia

    Directory of Open Access Journals (Sweden)

    Ronal Fernando-Cañon


    Full Text Available It was quantified the population of diazotrophic and phosphate solubilizer bacteria with the aim of determine the effect of the use of soils during different periods of intervention with culture of rice in three agro-ecological zones of the District of Irrigation of the Zulia river. The results showed that the management of the culture of rice in the different studied zones significantly influenced the population of microorganisms in all the studied culture media, excepting the semi-solid culture media JMV. The populations of the genera Azospirillum spp., Azotobacter spp., Beijerinckia spp., were influenced by the fertility of the soils in the zones of Buena Esperanza and Restauración compared with Limoncito, where the quantities of organic matter and nutritional escential elements were lower. It were obtained 28 isolations of entophytic, associative, free-living diazotrophic and phosphate solubilizer rhizobacteria according with their macroscopic characteristics in the culture media Batata, JMV, Ashby and nutritive, from the analysis of the population in the zones of Buena Esperanza, Restauración and Limoncito. These isolations were purified and preserved in sterilized saline solution (0.85% NaCl at 4°C in the Laboratory of Microbiology of the Colombian Agricultural Institute, ICA, with the purpose to be used in subsequent studies about their potential as biofertilizers in rice cultured soils of the department.

  8. Mechanical properties and failure behavior of unidirectional porous ceramics. (United States)

    Seuba, Jordi; Deville, Sylvain; Guizard, Christian; Stevenson, Adam J


    We show that the honeycomb out-of-plane model derived by Gibson and Ashby can be applied to describe the compressive behavior of unidirectional porous materials. Ice-templating allowed us to process samples with accurate control over pore volume, size, and morphology. These samples allowed us to evaluate the effect of this microstructural variations on the compressive strength in a porosity range of 45-80%. The maximum strength of 286 MPa was achieved in the least porous ice-templated sample (P(%) = 49.9), with the smallest pore size (3 μm). We found that the out-of-plane model only holds when buckling is the dominant failure mode, as should be expected. Furthermore, we controlled total pore volume by adjusting solids loading and sintering temperature. This strategy allows us to independently control macroporosity and densification of walls, and the compressive strength of ice-templated materials is exclusively dependent on total pore volume.

  9. Mutual information, perceptual independence, and holistic face perception. (United States)

    Fitousi, Daniel


    The concept of perceptual independence is ubiquitous in psychology. It addresses the question of whether two (or more) dimensions are perceived independently. Several authors have proposed perceptual independence (or its lack thereof) as a viable measure of holistic face perception (Loftus, Oberg, & Dillon, Psychological Review 111:835-863, 2004; Wenger & Ingvalson, Learning, Memory, and Cognition 28:872-892, 2002). According to this notion, the processing of facial features occurs in an interactive manner. Here, I examine this idea from the perspective of two theories of perceptual independence: the multivariate uncertainty analysis (MUA; Garner & Morton, Definitions, models, and experimental paradigms. Psychological Bulletin 72:233-259, 1969), and the general recognition theory (GRT; Ashby & Townsend, Psychological Review 93:154-179, 1986). The goals of the study were to (1) introduce the MUA, (2) examine various possible relations between MUA and GRT using numerical simulations, and (3) apply the MUA to two consensual markers of holistic face perception(-)recognition of facial features (Farah, Wilson, Drain, & Tanaka, Psychological Review 105:482-498, 1998) and the composite face effect (Young, Hellawell, & Hay, Perception 16:747-759, 1987). The results suggest that facial holism is generated by violations of several types of perceptual independence. They highlight the important theoretical role played by converging operations in the study of holistic face perception.

  10. Comparison of Frictional Heating Models

    Energy Technology Data Exchange (ETDEWEB)

    Davies, Nicholas R [ORNL; Blau, Peter Julian [ORNL


    The purpose of this work was to compare the predicted temperature rises using four well-known models for frictional heating under a few selected conditions in which similar variable inputs are provided to each model. Classic papers by Archard, Kuhlmann-Wilsdorf, Lim and Ashby, and Rabinowicz have been examined, and a spreadsheet (Excel ) was developed to facilitate the calculations. This report may be used in conjunction with that spreadsheet. It explains the background, assumptions, and rationale used for the calculations. Calculated flash temperatures for selected material combinations, under a range of applied loads and sliding speeds, are tabulated. The materials include AISI 52100 bearing steel, CDA 932 bronze, NBD 200 silicon nitride, Ti-6Al-4V alloy, and carbon-graphite material. Due to the assumptions made by the different models, and the direct way in which certain assumed quantities, like heat sink distances or asperity dimensions, enter into the calculations, frictional hearing results may differ significantly; however, they can be similar in certain cases in light of certain assumptions that are shared between the models.

  11. Individual Differences in Eye-Movements During Reading: Working Memory and Speed-of-Processing Effects. (United States)

    Traxler, Matthew J; Long, Debra L; Tooley, Kristen M; Johns, Clinton L; Zirnstein, Megan; Jonathan, Eunike

    Theories of eye-movement control in reading should ultimately describe how differences in knowledge and cognitive abilities affect reading and comprehension. Current mathematical models of eye-movement control do not yet incorporate individual differences as a source of variation in reading, although developmental and group-difference effects have been studied. These models nonetheless provide an excellent foundation for describing and explaining how and why patterns of eye-movements differ across readers (e.g., Rayner, Chace, & Ashby, 2006). Our focus in this article is on two aspects of individual variation: global processing speed (e.g., Salthouse, 1996) and working-memory capacity (e.g., Just & Carpenter, 1992). Using Hierarchical Linear Modeling (HLM) (Raudenbush & Bryk, 2001), we tested the extent to which overall reading speed and working-memory capacity moderate the degree to which syntactic and semantic information affect fixation times. Previous published data (Traxler et al., 2005) showed that working memory capacity and syntactic complexity interacted to determine fixation times in an eye-movement monitoring experiment. In a new set of models based on this same data set, we found that working-memory capacity interacted with sentence-characteristic variables only when processing speed was not included in the model. We interpret these findings with respect to current accounts of sentence processing and suggest how they might be incorporated into eye-movement control models.

  12. Perceived association between diagnostic and non-diagnostic cues of women's sexual interest: General Recognition Theory predictors of risk for sexual coercion. (United States)

    Farris, Coreen; Viken, Richard J; Treat, Teresa A


    Young men's errors in sexual perception have been linked to sexual coercion. The current investigation sought to explicate the perceptual and decisional sources of these social perception errors, as well as their link to risk for sexual violence. General Recognition Theory (GRT; [Ashby, F. G., & Townsend, J. T. (1986). Varieties of perceptual independence. Psychological Review, 93, 154-179]) was used to estimate participants' ability to discriminate between affective cues and clothing style cues and to measure illusory correlations between men's perception of women's clothing style and sexual interest. High-risk men were less sensitive to the distinction between women's friendly and sexual interest cues relative to other men. In addition, they were more likely to perceive an illusory correlation between women's diagnostic sexual interest cues (e.g., facial affect) and non-diagnostic cues (e.g., provocative clothing), which increases the probability that high-risk men will misperceive friendly women as intending to communicate sexual interest. The results provide information about the degree of risk conferred by individual differences in perceptual processing of women's interest cues, and also illustrate how translational scientists might adapt GRT to examine research questions about individual differences in social perception.

  13. Lead, arsenic and polycyclic aromatic hydrocarbons in soil and house dust in Sydney Nova Scotia

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, T.W. [Calgary Univ., AB (Canada); Lane, S. [York Univ., Toronto, ON (Canada). School of Environmental Studies


    This paper presents the results of a lead and arsenic soil and dust study conducted in Sydney, Nova Scotia in August 2002. Whitney Pier, Ashby and North End are 3 communities surrounding the Sydney tar ponds, steel and coke oven sites that have been significantly impacted by the industrial activity of the past century. Lead and arsenic was found in the floor dust of every home evaluated. The neighbourhoods were also found to be contaminated with polycyclic aromatic hydrocarbons (PAHs). There is a low but significant health risk from exposure to lead and arsenic in the soil and house dust, and all three communities must be remediated to prevent health impacts. This report by the Sierra Club criticizes an earlier report by the Joint Action Group (JAG), a tri-governmental process which never took into consideration the fact that people's yards and homes are contaminated and need to be remediated. This report criticizes that the JAG report neglected the issue of people's health and is calling on the federal Health Minister to take action on the environmental disaster. 17 refs., 8 tabs., 1 fig.

  14. Understanding the application of knowledge management to the safety critical facilities

    Energy Technology Data Exchange (ETDEWEB)

    Ilina, Elena


    Challenges to the operating nuclear power plants and transport infrastructures are outlined. It is concluded that most aggravating factors are related to knowledge. Thus, of necessity, effective knowledge management is required. Knowledge management theories are reviewed in their historical perspective as a natural extension and unification of information theories and theories about learning. The first line is identified with names as Wiener, Ashby, Shannon, Jaynes, Dretske, Harkevich. The second line - with Vygotsky, Engestroem, Carayannis. The recent developments of knowledge management theorists as Davenport, Prusak, Drew, Wiig, Zack are considered stressing learning, retaining of knowledge, approaching the state awareness of awareness, and alignment of knowledge management with the strategy of the concerned organizations. Further, some of the details and results are presented of what is achieved so far. More specifically, knowledge management tools are applied to the practical work activities as event reporting, data collection, condition assessment, verification of safety functions and incident investigation. Obstacles are identified and improvements are proposed. Finally, it is advised to continue to implement and further develop knowledge management tools in the organizations involved in various aspects of safety critical facilities

  15. A molecular dynamics study of void initiation and growth in monocrystalline and nanocrystalline copper (United States)

    Traiviratana, Sirirat

    MD simulations in monocrystalline and nanocrystalline copper were carried out with LAMMPS to reveal void growth mechanisms. The specimens were subjected to both tensile uniaxial and hydrostatic strains; the results confirm that the emission of (shear) loops is the primary mechanism of void growth. The expansion of the loops and their cross slip leads to the severely work hardened layer surrounding a growing void. Calculations were carried out on voids with different sizes, and a size dependence of the stress response to emitted dislocations was observed, in disagreement with the Gurson model [1] which is scale independent. The growth of voids simulated by MD is compared with the Cocks-Ashby constitutive model and significant agreement is found. The density of geometrically-necessary dislocations as a function of void size is calculated based on the emission of shear loops and their outward propagation. Calculations were also carried out for a void at the interface between two grains sharing a tilt boundary. The results show similar dislocation behaviors. A code that uses Voronoi tessellation for constructing nanocrystalline structures was developed and used to prepare the structures for simulations. Nanocrystal simulations reveal grain sliding and grain rotation as the nanocrystal deformed. Voids were nucleated at grain junctions and grew to coalescence as dislocations accommodated the material transfer. A code that can be used during post-processing to extract useful dislocation information from MD simulation data was partially developed and proved the feasibility of automatically analyzing dislocations.

  16. Creep of the Copper Canister. A Critical Review of the Literature

    Energy Technology Data Exchange (ETDEWEB)

    Bowyer, William H. [Meadow End Farm, Farnham (United Kingdom)


    Literature relevant to creep of the copper shell of the copper-iron canister has been reviewed. Two classes of copper have been examined, Oxygen Free High Conductivity (OFHC), which is referred to in the relevant literature and this report as OF material, and OF material with 50 ppm of phosphorus added. The second material is referred to as OFP. Creep processes occurring in copper are briefly described and a deformation diagram, after Frost and Ashby is provided. It is concluded that the diagram adequately describes the processes observed for the two materials of interest without necessarily being in exact agreement at a quantitative level. There are two regimes of time, temperature and stress which are important when creep of the copper shell is considered. The first is a holding period between welding of the lid to the canister and placing the canister in the repository and the second is the storage period in the repository. In the holding period, residual stresses arising from the manufacturing processes are important and in the second period stresses arising from repository pressures are important as well as the residual pressures arising from manufacture. The holding period may extend up to one year and the temperature of the copper shell may decline from the immediate post welding temperature to 100 deg C in this interval. Initial peak localised stresses may give rise to strains of up to 14 %. Dynamic recovery immediately after welding reduces the stresses associated with these strains to levels which correspond to stresses for approximately 0.1 % strain at the ruling temperature. This is 75 MPa at 100 deg C and 50 MPa for 150 deg C. A further stress relaxation of up to 30 % occurs in the first 20 days after welding. Localised stresses are therefore unlikely to exceed 50 MPa when the canister is placed into storage. No negative effects have been observed in connection with this stress relaxation process. In the storage period, which is indefinite, the

  17. Archaeologies of Hair: an introduction

    Directory of Open Access Journals (Sweden)

    Steven P. Ashby


    Full Text Available This collection of short articles represents an original attempt to bring together scholarship that is usually divided along lines of specialism in time, place, method, or discipline. The shared focus of its contributions is on hair: more than an infrequently preserved element of human remains, but a widespread (and arguably cross-cultural symbol of power, of fertility, of identity and the self. Moreover, its care and treatment using various forms of material culture, and its artistic representation in diverse media, offer a unique opportunity to examine the interface between the body and material culture. Where exceptional taphonomic conditions facilitate the preservation of hair and associated organic material, the result is some of the richest assemblages of human remains and associated material culture in the archaeological record (e.g. Wilson et al. 2007; Fletcher 1998. In contrast, 'everyday' objects associated with haircare are among the most taphonomically robust, frequently encountered and recognisable personal items known to archaeologists (e.g. Stephens 2008; Ashby 2011, and provide us with insight into the making of personal and bodily identities, even in the absence of human remains themselves. When studied in an interdisciplinary framework, the interpretative potential of this material is clear, but such work has been rare. This collection aims to set a new agenda for cross-disciplinary research focused on the nexus of human and artefactual remains, by highlighting the rich and diverse potential of this material when studied through archaeological, biochemical, artistic, historical, sociological and anthropological lenses.

  18. Regressions during reading: The cost depends on the cause. (United States)

    Eskenazi, Michael A; Folk, Jocelyn R


    The direction and duration of eye movements during reading is predominantly determined by cognitive and linguistic processing, but some low-level oculomotor effects also influence the duration and direction of eye movements. One such effect is inhibition of return (IOR), which results in an increased latency to return attention to a target that has been previously attended (Posner & Cohen, Attention and Performance X: Control of Language Processes, 32, 531-556, 1984). Although this is a low level effect, it has also been found in the complex task of reading (Henderson & Luke, Psychonomic Bulletin & Review, 19(6), 1101-1107, 2012; Rayner, Juhasz, Ashby, & Clifton, Vision Research, 43(9), 1027-1034, 2003). The purpose of the current study was to isolate the potentially different causes of regressive eye movements: to adjust for oculomotor error and to assist with comprehension difficulties. We found that readers demonstrated an IOR effect when regressions were caused by oculomotor error, but not when regressions were caused by comprehension difficulties. The results suggest that IOR is primarily associated with low-level oculomotor control of eye movements, and that regressive eye movements that are controlled by comprehension processes are not subject to IOR effects. The results have implications for understanding the relationship between oculomotor and cognitive control of eye movements and for models of eye movement control.

  19. Selection of materials with potential in sensible thermal energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, A.I.; Martinez, M.; Segarra, M. [Department of Materials Science and Metallurgical Engineering, Universitat de Barcelona, Marti i Franques 1, 08028 Barcelona (Spain); Martorell, I.; Cabeza, L.F. [GREA Innovacio Concurrent, Edifici CREA, Universitat de Lleida, Pere de Cabrera s/n, 25001 Lleida (Spain)


    Thermal energy storage is a technology under investigation since the early 1970s. Since then, numerous new applications have been found and much work has been done to bring this technology to the market. Nevertheless, the materials used either for latent or for sensible storage were mostly investigated 30 years ago, and the research has lead to improvement in their performance under different conditions of applications. In those years a significant number of new materials were developed in many fields other than storage and energy, but a great effort to characterize and classify these materials was done. Taking into account the fact that thousands of materials are known and a large number of new materials are developed every year, the authors use the methodology for materials selection developed by Prof. Ashby to give an overview of other materials suitable to be used in thermal energy storage. Sensible heat storage at temperatures between 150 and 200 C is defined as a case study and two different scenarios were considered: long term sensible heat storage and short term sensible heat storage. (author)

  20. Comparing the neural basis of monetary reward and cognitive feedback during information-integration category learning. (United States)

    Daniel, Reka; Pollmann, Stefan


    The dopaminergic system is known to play a central role in reward-based learning (Schultz, 2006), yet it was also observed to be involved when only cognitive feedback is given (Aron et al., 2004). Within the domain of information-integration category learning, in which information from several stimulus dimensions has to be integrated predecisionally (Ashby and Maddox, 2005), the importance of contingent feedback is well established (Maddox et al., 2003). We examined the common neural correlates of reward anticipation and prediction error in this task. Sixteen subjects performed two parallel information-integration tasks within a single event-related functional magnetic resonance imaging session but received a monetary reward only for one of them. Similar functional areas including basal ganglia structures were activated in both task versions. In contrast, a single structure, the nucleus accumbens, showed higher activation during monetary reward anticipation compared with the anticipation of cognitive feedback in information-integration learning. Additionally, this activation was predicted by measures of intrinsic motivation in the cognitive feedback task and by measures of extrinsic motivation in the rewarded task. Our results indicate that, although all other structures implicated in category learning are not significantly affected by altering the type of reward, the nucleus accumbens responds to the positive incentive properties of an expected reward depending on the specific type of the reward.

  1. Perfectionism, shame, and self-concept in dancers: a mediation analysis. (United States)

    Eusanio, Jacqueline; Thomson, Paula; Jaque, S Victoria


    Perfectionism has been linked to various forms of physiological and psychological maladjustment. This study examined the inter-relationships between multi-dimensional aspects of perfectionism (self-oriented, other-oriented, and socially prescribed), internalized shame, and total self-concept in elite dancers (N = 24) as compared to a control group of healthy, active non-dancers (N = 23). All participants completed psychometric self-report measures targeting the variables of interest. Multivariate analysis of covariance (gender as covariate) indicated that the dancers had higher levels of self-oriented perfectionism than the control group. Building on the findings of Ashby, Rice, and Martin, we examined a model in which dancers' shame mediates the relationship between maladaptive aspects of perfectionism and self-concept. Analysis revealed internalized shame to fully mediate the relationship between dancers' socially prescribed perfectionism and total self-concept; however, shame did not mediate self-concept in the control group. We conclude that dancers would benefit from programs that enhance self-esteem and reduce the negative effects of internalized shame and self-oriented and socially prescribed perfectionism.

  2. Learning to Associate Auditory and Visual Stimuli: Behavioral and Neural Mechanisms (United States)

    Altieri, Nicholas; Stevenson, Ryan; Wallace, Mark T.; Wenger, Michael J.


    The ability to effectively combine sensory inputs across modalities is vital for acquiring a unified percept of events. For example, watching a hammer hit a nail while simultaneously identifying the sound as originating from the event requires the ability to identify spatio-temporal congruencies and statistical regularities. In this study, we applied a reaction time (RT) and hazard function measure known as capacity (e.g., Townsend and Ashby, 1978) to quantify the extent to which observers learn paired associations between simple auditory and visual patterns in a model theoretic manner. As expected, results showed that learning was associated with an increase in accuracy, but more significantly, an increase in capacity. The aim of this study was to associate capacity measures of multisensory learning, with neural based measures, namely mean Global Field Power (GFP). We observed a co-variation between an increase in capacity, and a decrease in GFP amplitude as learning occurred. This suggests that capacity constitutes a reliable behavioral index of efficient energy expenditure in the neural domain. PMID:24276220

  3. Unravelling the materials genome: Symmetry relationships in alloy properties

    Energy Technology Data Exchange (ETDEWEB)

    Toda-Caraballo, Isaac [Department of Materials Science and Metallurgy, University of Cambridge New Museums Site, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom); Galindo-Nava, Enrique I. [Department of Materials Science and Metallurgy, University of Cambridge New Museums Site, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom); Delft University of Technology, Mekelweg 2, Delft 2628 CD (Netherlands); Rivera-Díaz-del-Castillo, Pedro E.J., E-mail: [Department of Materials Science and Metallurgy, University of Cambridge New Museums Site, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom)


    Highlights: ► Research strategy for Accelerated Metallurgy project is outlined. ► Surprising symmetry among atomic, nanoscale and mechanical properties. ► Generalisation of Ashby diagrams via principal component analysis. ► Atomic-related properties can be described with linear regression. ► Mechanical properties modelled via Kocks–Mecking-type physical method. -- Abstract: Metals and alloys have been indispensable for technological progress, but only a fraction of the possible ternary systems (combinations of three elements) is known. Statistical inference methods combined with physical models are presented to discover new systems of enhanced properties. It is demonstrated that properties originating from atomic-level interactions can be described employing a linear regression analysis, but properties incorporating microstructural and thermal history effects require a balance between physical and statistical modelling. In spite of this, there is a remarkable degree of symmetry among all properties, and by employing a principal components analysis it is shown that ten properties essential to engineering can be described well in a three dimensional space. This will aid in the discovery of novel alloying systems.

  4. Somatic recombination, gene amplification and cancer. (United States)

    Ramel, C; Cederberg, H; Magnusson, J; Vogel, E; Natarajan, A T; Mullender, L H; Nivard, J M; Parry, J M; Leyson, A; Comendador, M A; Sierra, L M; Ferreiro, J A; Consuegra, S


    The principle objective of this research programme, to analyse chemical induction of somatic recombination and related endpoints, i.e., mobilization of transposing elements and gene amplification, has been approached by means of several assay systems. These have included Drosophila, Saccharomyces and mammalian cell cultures. 6.1. Screening assays for mitotic recombination. A large number of chemicals have been investigated in the three Drosophila assay systems employed--the multiple wing hair/flare wing spot system developed by Graf et al., 1984, the white-ivory system developed by Green et al., 1986 and the white/white+ eye spot assay developed by Vogel (Vogel and Nivard, 1993). Particularly the screening of 181 chemicals, covering a wide array of chemical classes, by the last mentioned assay has shown that measurement of somatic recombination in Drosophila constitutes a sensitive and efficient short-term test which shows a remarkably good correlation with the agent score of 83 short-term tests analysed by ICPEMC (Mendelsohn et al., 1992; Table 2) as well as the assay performance in international collaborative programmes measuring carcinogen/non-carcinogens (de Serres and Ashby, 1981; Ashby et al., 1985, 1988). Also the wing spot assay has gained wide international recognition as a similarly sensitive test. These two assay systems in Drosophila measure both intrachromosomal events and interchromosomal recombination. The white-ivory system on the other hand is based on the loss of a tandem duplication in the white locus, the mechanism of which is less known, but probably involves intrachromosomal recombination. The difference in the mechanism between this assay and the former two was indicated by the lack of response to methotrexate in the white-ivory assay, while this compound was strongly recombinogenic in both the wing spot and white/white+ assays. The use of different strains of Drosophila with the white/white+ assay demonstrated the importance of the

  5. Supramolecular Engineering of Hierarchically Self-Assembled, Bioinspired, Cholesteric Nanocomposites Formed by Cellulose Nanocrystals and Polymers. (United States)

    Zhu, Baolei; Merindol, Remi; Benitez, Alejandro J; Wang, Baochun; Walther, Andreas


    Natural composites are hierarchically structured by combination of ordered colloidal and molecular length scales. They inspire future, biomimetic, and lightweight nanocomposites, in which extraordinary mechanical properties are in reach by understanding and mastering hierarchical structure formation as tools to engineer multiscale deformation mechanisms. Here we describe a hierarchically self-assembled, cholesteric nanocomposite with well-defined colloid-based helical structure and supramolecular hydrogen bonds engineered on the molecular level in the polymer matrix. We use reversible addition-fragmentation transfer polymerization to synthesize well-defined hydrophilic, nonionic polymers with a varying functionalization density of 4-fold hydrogen-bonding ureidopyrimidinone (UPy) motifs. We show that these copolymers can be coassembled with cellulose nanocrystals (CNC), a sustainable, stiff, rod-like reinforcement, to give ordered cholesteric phases with characteristic photonic stop bands. The dimensions of the helical pitch are controlled by the ratio of polymer/CNC, confirming a smooth integration into the colloidal structure. With respect to the effect of the supramolecular motifs, we demonstrate that those regulate the swelling when exposing the biomimetic hybrids to water, and they allow engineering the photonic response. Moreover, the amount of hydrogen bonds and the polymer fraction are decisive in defining the mechanical properties. An Ashby plot comparing previous ordered CNC-based nanocomposites with our new hierarchical ones reveals that molecular engineering allows us to span an unprecedented mechanical property range from highest inelastic deformation (strain up to ∼13%) to highest stiffness (E ∼ 15 GPa) and combinations of both. We envisage that further rational design of the molecular interactions will provide efficient tools for enhancing the multifunctional property profiles of such bioinspired nanocomposites.

  6. 超塑性纳米纤维状滑动带控制孕震断层摩擦

    Institute of Scientific and Technical Information of China (English)

    Berend A Verberne; Oliver Plümper; D A Matthij s de Winter; Christopher J Spiers


    了解控制断层摩擦的内在机制对于了解活动断层的孕震滑动十分关键。断层带中的位移常常局限在高反射(镜面)的滑动面上,通常滑动面上还覆盖有薄层的纳米颗粒状断层岩。本文展示了实验模拟的方解石断层中发育的镜面状滑动面,它由在室温条件下呈韧性的纳米颗粒链或是纳米纤维线性排列组成。这些微结构和相应的摩擦数据表明,断层滑动机制类似于经典的 Ashby-Verrall超塑性,该机制能够产生不稳定的断层滑动。对这种机制而言,纳米晶体方解石断层泥中的扩散物质转移速度足够快,以致于可以控制石灰岩地区的孕震活动。随着壳内断层上越来越多地被证实存在着纳米颗粒状断层面,本文提出的机制很有可能普遍适用于壳内孕震活动。

  7. 酚醛泡沫力学性能及其密度-力学性能模型研究%Research on Mechanical Properties and Densities-Mechanical Properties Model of Phenolic Foam

    Institute of Scientific and Technical Information of China (English)

    马玉峰; 张伟; 王春鹏; 储富祥


    以多聚甲醛代替甲醛溶液制备高固含可发性酚醛树脂,在70℃发泡制备酚醛泡沫材料,研究了表面活性剂、固化剂和发泡剂对泡沫的密度、力学性能的影响.研究结果表明,在表面活性剂添加量为12%,固化剂添加量为30%,发泡剂添加量为5%时,制备的泡沫性能较优.通过Gibson-Ashby提出的泡沫塑料的力学性能与密度的关系模型,创建酚醛泡沫密度-力学性能模型,结果表明泡沫力学性能与密度呈现良好的指数关系,且间接拟合和直接拟合2种方法得出的模型指数基本相符.%Paraformaldehyde was used to instead of formaldehyde to prepare high solids and expandable phenolic resin, and phenolic resin was used to prepare phenolic foam at 70℃. The influences of the surface-active agent,curing agent and blowing agent on foam density, mechanical properties were researched. The results showed that when the amount of surfactant,blowing agent,curing agent was 12%,30%,5% respectively,the properties of foam was better. The model of phenolic foam density-mechanical properties was established by the foam model of Gibson-Ashby's mechanical properties and density, the results showed that there was good exponential relationship between mechanical properties and density, and exponents acquired by indirect and direct fitting were basically consistent.

  8. Vibration-Assisted Sputter Coating of Cenospheres: A New Approach for Realizing Cu-Based Metal Matrix Syntactic Foams

    Directory of Open Access Journals (Sweden)

    Andrei Shishkin


    Full Text Available The coating of hollow alumino-silicate microspheres or cenospheres with thin layers of Cu by means of vibration-assisted magnetron sputtering yields a starting material with considerable potential for the production of new types of metal matrix syntactic foams as well as optimized variants of conventional materials of this kind. This study introduces the coating process and the production of macroscopic samples from the coated spheres via spark plasma sintering (SPS. The influence of processing parameters on the coating itself, and the syntactic foams are discussed in terms of the obtained density levels as a function of sintering temperature (which was varied between 850 and 1080 °C, time (0.5 to 4 min, and surface appearance before and after SPS treatment. Sintering temperatures of 900 °C and above were found to cause breaking-up of the homogeneous sputter coating into a net-like structure. This effect is attributed to wetting behavior of Cu on the alumino-silicate cenosphere shells. Cylindrical samples were subjected to conductivity measurements and mechanical tests, and the first performance characteristics are reported here. Compressive strengths for Cu-based materials in the density range of 0.90–1.50 g/cm3 were found to lie between 8.6 and 61.9 MPa, depending on sintering conditions and density. An approximate relationship between strength and density is suggested based on the well-known Gibson–Ashby law. Density-related strength of the new material is contrasted to similar findings for several types of established metal foams gathered from the literature. Besides discussing these first experimental results, this paper outlines the potential of coated microspheres as optimized filler particles in metal matrix syntactic foams, and suggests associated directions of future research.


    Directory of Open Access Journals (Sweden)

    Juliano Pereira da Silva


    Full Text Available This Project arises from a desire to continue the monograph work done in 2010 in the course of Specialization in Teaching History and Social History at the State University of Londrina whose title was "The use RPG as a pedagogical tool in teaching history." The RPG proved to be a good teaching tool in that it aroused in students a love of history and his ability to put yourself in someone else's past, in other words, to establish an empathetic relationship with the past. It is the in-depth study of this relationship we wish to discuss. The historical empathy for Ashby & Lee serve as "a venture where students show the ability to reconstruct the goals, feelings, values and beliefs of others, accepting that they maybe different from your", thus becoming na important element in the teaching-learning process. The objective of this new phase was to verify the occurrence of historical empathic experience among students ofthe 6th year of the elementar school Professor Dr. Heber Soares Vargas of the content of history from a RPG game, watching their relationship in the seizure of historical concepts by students. This empathic experience occurred, helping many students to understand the concepts related to substantive matters studied from a historical perspective created in an RPG game. The project consisted of literature in order to define some concepts like game and the concept of historical empathy and its use in the teaching of history; creation of educational material, analysis of students' ideas and reflection on the experiment performed. Was conducted among the students of the sixth grade of elementary school in State College Professor. Dr. Heber Smith Vargas.

  10. 1000 MW超超临界汽轮机高压外缸蠕变强度的分析%Creep Strength Analysis on HP Outer Casing of a 1 000 MW Ultra Supercritical Steam Turbine

    Institute of Scientific and Technical Information of China (English)



    以1 000 MW超超临界汽轮机高压外缸为研究对象,通过引入Norton-Bailey材料蠕变本构方程和Cocks-Ashby多轴韧度系数,对汽缸轴对称二维模型的温度场、应力场和CA蠕变等效应变分布进行了计算,找出了结构设计中不合理区域并提出相应的结构改进方案.结果表明:经改进的高压外缸结构设计是合理的;CA蠕变等效应变计算结果均小于推荐考核标准,该1 000 MW超超临界汽轮机高压外缸的高温蠕变应变强度能够满足设计要求.%Taking the high-pressure outer casing of a 1 000 MW ultra supercritical steam turbine as an object of study, and by adopting the Norton-Bailey material creep constitutive equation and Cocks-Ashby multiaxial coefficient, the temperature field, stress field and the CA equivalent creep strain dictribution of the 2D axisymmetric model were calculated, during which the unreasonable structure of original design was found out and impoved with corresponding schemes. Results show that the improved structure of the HP outer casing is reasonable; all the calculated results of CA equivalent creep strain are less than those in the recommended criteria for assessment. The high-temperature creep strain of above mentioned outer casing can meet the design requirements.

  11. 高级别管线钢板的组织特征与析出强化%Microstructure Characteristics and Precipitation Strengthening of High Grade Pipeline Steels

    Institute of Scientific and Technical Information of China (English)

    康永林; 牛涛; 尹雨群; 谯明亮


    利用扫描电镜、透射电镜对炉卷轧机生产的高级别X70,X80管线钢板的显微组织与析出相进行了观察与分析,并对管线钢板组织中碳氮化物析出相的成分、相结构以及粒度分布进行了定量分析,并采用Ashby-Orowan修正模型对析出粒子的强化贡献进行了理论计算.结果表明:X70,X80管线钢板的组织以针状铁素体为主,其高密度位错与交叉分布的大角度晶界特点保证了管线钢的高强韧性;X70,X80管线钢板中的析出相主要有两种类型,一种为尺寸较小的NbC析出相(1~30 nm),另一种为尺寸较大的(Ti,Nb)(C,N)复合析出相(50~300 nm),两种类型均为面心立方结构;生产工艺对析出相的粒度分布有明显影响,避开900~950 ℃碳氮化物的快速析出温度区间,以及适当增加冷却速度可以有效提高20 nm以下的析出粒子体积分数,细化析出物尺寸,从而提高析出强化对屈服强度的贡献.

  12. 闭孔泡沫Zn-22Al在单轴准静态加载下的压缩行为%Compressive behavior of Zn-22Al closed-cell foams under uniaxial quasi-static loading

    Institute of Scientific and Technical Information of China (English)



    通过使用氢化物发泡剂,采用熔体发泡法制备闭孔泡沫Zn−Al合金,在准静态条件下研究其压缩性能。在压缩试样过程中,分析发泡材料的结构,并研究其形态和压缩性能之间的关系。结果表明,应力−应变行为具有典型的闭孔泡沫金属和脆性泡沫金属的特征;在平稳阶段的控制变形机制是脆性破碎;泡沫Zn−22Al合金的抗压强度得到了显著提高,其压缩性能符合Gibson−Ashby模型。%Zn−22Al alloy closed-cell foams were fabricated by melt foaming process using hydride foaming agent. The compressive properties were investigated under quasi-static condition. The structure of the foamed material was analyzed during compression test to reveal the relationship between morphology and compressive behavior. The results show that the stress−strain behavior is typical of closed-cell metal foams and mostly of brittle type. Governing deformation mechanism at plateau stage is identified to be brittle crushing. A substantial increase in compressive strength of Zn−22Al foams was obtained. The agreement between compressive properties and Gibson−Ashby model was also detected.

  13. 闭孔泡沫铝的力学性能和吸能能力%Mechanical Properties and Energy Absorption Capability of Closed-cell Al Foam

    Institute of Scientific and Technical Information of China (English)

    王展光; 蔡萍; 应建中; 李书琴; 胡景智


    在闭孔泡沫铝准静态压缩试验的基础上,研究了其力学性能、吸能能力.结果表明,闭孔泡沫铝单轴压缩应力-应变曲线呈现践弹性变形、塑性平台阶段、致密化阶段3个阶段;闭孔泡沫铝的压缩强度、吸能能力随着孔隙率的增大而减小,采用Gibson-Ashby模型分析闭孔泡沫铝的压缩屈服强度,吻合良好.并在此基础上,提出可供工程使用的多孔泡沫金属吸能能力公式,为其工程应用提供理论支持.%Based on the compressive test of closed-cell Al foam, mechanical properties and energy absorption capacity under uniaxial compression were investigated. Compressive stress-strain curve of closed-cell Al foam consists of three distinct rcgions, the linear elasticity region, the plastic collapse region and the densification region. Compressive strength and energy absorption capacity of closed-cell Al foam decreases with the increase of porosity. Compressive yield stress is in good agreement with Gibson-Ashby model's expectation. Formula on energy absorption capability of closed-cell Al alloy foam was presentedt which could provide theoretical support for its engineering application.

  14. Mechanical properties and energy absorption capability of closed-cell Al foam under uniaxial compression%闭孔胞状泡沫铝的单向压缩力学性能和吸能能力

    Institute of Scientific and Technical Information of China (English)

    王展光; 蔡萍; 李书琴


    Based on the uniaxial compressive test of different porosity closed-cell Al foam, the effect of porosity on mechanical properties and energy absorption capacity were investigated. Compressive stress-strain curve of closed-cell Al foam consists of three distinct regions, which is the linear region, the collapse region and the densification region. The compressive strength and energy absorption capacity of closed-cell Al foam decrease with the increase of porosity. Analyzing the compressive yield stress by Gibson-Ashby model, formula on energy absorption capability of Al foam was presented, which could provide support for its engineering application.%通过不同孔隙度闭孔胞状泡沫铝的准静态压缩试验,研究泡沫铝孔隙度对其力学性能和吸能能力的影响.闭孔胞状泡沫铝单轴压缩应力应变曲线呈现明显的3个阶段:线性变形、平台阶段、致密化阶段;在单向压缩情况下,泡沫铝的压缩强度、吸能能力随着孔隙度的增大而减小;采用Gibson-Ashby的模型分析闭孔胞状泡沫铝的压缩屈服强度,并提出泡沫铝吸能能力公式,为工程应用提供理论支持.

  15. An atom probe perspective on phase separation and precipitation in duplex stainless steels (United States)

    Guo, Wei; Garfinkel, David A.; Tucker, Julie D.; Haley, Daniel; Young, George A.; Poplawsky, Jonathan D.


    Three-dimensional chemical imaging of Fe-Cr alloys showing Fe-rich (α)/Cr-rich (α‧) phase separation is reported using atom probe tomography techniques. The extent of phase separation, i.e., amplitude and wavelength, has been quantitatively assessed using the Langer-Bar-on-Miller, proximity histogram, and autocorrelation function methods for two separate Fe-Cr alloys, designated 2101 and 2205. Although the 2101 alloy possesses a larger wavelength and amplitude after annealing at 427 °C for 100-10 000 h, it exhibits a lower hardness than the 2205 alloy. In addition to this phase separation, ultra-fine Ni-Mn-Si-Cu-rich G-phase precipitates form at the α/α‧ interfaces in both alloys. For the 2101 alloy, Cu clusters act to form a nucleus, around which a Ni-Mn-Si shell develops during the precipitation process. For the 2205 alloy, the Ni and Cu atoms enrich simultaneously and no core-shell chemical distribution was found. This segregation phenomenon may arise from the exact Ni/Cu ratio inside the ferrite. After annealing for 10 000 h, the number density of the G-phase within the 2205 alloy was found to be roughly one order of magnitude higher than in the 2101 alloy. The G-phase precipitates have an additional deleterious effect on the thermal embrittlement, as evaluated by the Ashby-Orowan equation, which explains the discrepancy between the hardness and the rate of phase separation with respect to annealing time (Gladman T 1999 Mater. Sci. Tech. Ser. 15 30-36). ).

  16. 以尿素为造孔剂制备开孔NiAl金属间化合物%Open-celled porous NiAl intermetallics prepared by replication of carbamide space-holders

    Institute of Scientific and Technical Information of China (English)

    吴杰; 崔洪芝; 曹丽丽; 谷征征


    以尿素为造孔剂,利用燃烧合成技术成功制备孔洞结构和力学性能可控可调的开孔NiAl金属间化合物,并对材料的宏观和微观形貌、准静态压缩性能进行分析.通过调整尿素的体积分数和颗粒大小,多孔NiAl金属间化合物的孔隙率可控制在57.57%-84.58%,孔径大小可控制在0.4-2.0 mm.准静态压缩实验表明,多孔NiAl金属间化合物的力学性能可用Gibson-Ashby模型来解释.%Open-celled porous NiAl intermetallics with adjustable pore characteristics and mechanical properties were successfully prepared by using spherical carbamide as space-holders via combustion synthesis.Examinations of macroscopic and microscopic morphologies as well as the quasi-static compressive test for the resultant materials were carried out.Depending on the volume fraction and particle size of the carbamide,the porosity and pore size of the porous NiAl intermetallics can be controlled freely in a range of 57.57%-84.58% and 0.4-2.0 mm,respectively.Furthermore,quasi-static compressive tests indicate that the mechanical behavior of the present porous materials is in good agreement with the Gibson-Ashby model.

  17. Foam behavior of solid glass spheres – Zn22Al2Cu composites under compression stresses

    Energy Technology Data Exchange (ETDEWEB)

    Aragon-Lezama, J.A., E-mail: [Departamento de Materiales, Universidad Autónoma Metropolitana-A, Avenida San Pablo 180, Colonia Reynosa Tamaulipas, 02200 México, D.F., México (Mexico); Garcia-Borquez, A., E-mail: [Ciencia de Materiales, ESFM – Instituto Politécnico Nacional, Edif. 9, Unid. Prof. A. Lopez Mateos, Colonia Lindavista, 07738 México, D.F., México (Mexico); Torres-Villaseñor, G., E-mail: [Departamento de Metálicos y Cerámicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apdo., P 70-360, México, D.F., México (Mexico)


    Solid glass spheres – Zn22Al2Cu composites, having different densities and microstructures, were elaborated and studied under compression. Their elaboration process involves alloy melting, spheres submersion into the liquid alloy and finally air cooling. The achieved composites with densities 2.6884, 2.7936 and 3.1219 g/cm{sup 3} were studied in casting and thermally induced, fine-grain matrix microstructures. Test samples of the composites were compressed at a 10{sup −3} s{sup −1} strain rate, and their microstructure characterized before and after compression by using optical and scanning electron microscopes. Although they exhibit different compression behavior depending on their density and microstructure, all of them show an elastic region at low strains, reach their maximum stress (σ{sub max}) at hundreds of MPa before the stress fall or collapse up to a lowest yield point (LYP), followed by an important plastic deformation at nearly constant stress (σ{sub p}): beyond this plateau, an extra deformation can be limitedly reached only by a significant stress increase. This behavior under compression stresses is similar to that reported for metal foams, being the composites with fine microstructure which nearest behave to metal foams under this pattern. Nevertheless, the relative values of the elastic modulus, and maximum and plateau stresses do not follow the Ashby equations by changing the relative density. Generally, the studied composites behave as foams under compression, except for their peculiar parameters values (σ{sub max}, LYP, and σ{sub p})

  18. Isothermal and aniso-thermal creep in the {alpha} phase domain, {beta} phase domain and {alpha}+{beta} two phase domain in a Zr-1%NbO alloy; Fluage isotherme et anisotherme dans les domaines monophases ({alpha} et {beta}) et biphases ({alpha} et {beta}) d'un alliage Zr-1%NbO

    Energy Technology Data Exchange (ETDEWEB)

    Kaddour, D


    The coupling between phase transformation and mechanical behaviour of a Zr-1%NbO alloy was studied using an original experimental device already used in a previous study devoted to the Zy-4 alloy. The Zr-1%NbO alloy undergoes a phase transformation {alpha} (hc) {r_reversible} (cc) typically between 750 and 1000 C. The transformation temperatures were measured in situ by using the resistivity and dilatometry techniques. The isothermal creep behaviour of fuel cladding tubes was studied, first after heating, in the {alpha} phase domain between 650 and 760 C, in the {beta} phase domain between 960 and 1100 C, as well as in the ({alpha} + {beta}) two phase domain between 800 and 900 C. The results are summarized in Ashby deformation mechanism maps. It is confirmed that the {beta} phase is much more sensitive to creep flow than the {alpha} phase. The effect of microstructure on the isothermal creep flow behaviour was then investigated by first applying a thermal cycle involving either a full or a partial transformation from {alpha} to {beta}. It was investigated both in the {alpha} phase domain, and after direct cooling into the ({alpha} + {beta}) phase domain. The behaviour in aniso-thermal conditions was finally studied at heating and cooling rates of 10 and 200 C/min. In both cases, we showed that there is no significant transformation plasticity in the stress range under investigation ({<=} 5 MPa). A finite element model using Voronoi polyhedra and eventually meshing a film of intergranular {beta} phase was used to describe the behaviour of material in the ({alpha} + {beta}) domain in various microstructural states. The model predictions are in good agreement with the experimental results for the microstructure obtained after cooling, but the model underestimates creep deformation in the as-received state. This difference is probably related to the fact that interface sliding is not taken into account in the model. (author)

  19. STS-112 Flight Day 4 Highlights (United States)


    On the fourth day of STS-112, its crew (Jeffrey Ashby, Commander; Pamela Melroy, Pilot; David Wolf, Mission Specialist; Piers Sellers, Mission Specialist; Sandra Magnus, Mission Specialist; Fyodor Yurchikhin, Mission Specialist) onboard Atlantis and the Expedition 5 crew (Valery Korzun, Commander; Peggy Whitson, Flight Engineer; Sergei Treschev, Flight Engineer) onboard the International Space Station (ISS) are seen preparing for the installation of the S1 truss structure. Inside the Destiny Laboratory Module, Korzun and other crewmembers are seen as they busily prepare for the work of the day. Sellers dons an oxygen mask and uses an exercise machine in order to purge the nitrogen from his bloodstream, in preparation for an extravehicular activity (EVA). Whitson uses the ISS's Canadarm 2 robotic arm to grapple the S1 truss and remove it from Atlantis' payload bay, with the assistance of Magnus. Using the robotic arm, Whitson slowly maneuvers the 15 ton truss structure into alignment with its attachment point on the starboard side of the S0 truss structure, where the carefully orchestrated mating procedures take place. There is video footage of the entire truss being rotated and positioned by the arm, and ammonia tank assembly on the structure is visible, with Earth in the background. Following the completion of the second stage capture, the robotic arm is ungrappled from truss. Sellers and Wolf are shown exiting the the Quest airlock hatch to begin their EVA. They are shown performing a variety of tasks on the now attached S1 truss structure, including work on the Crew Equipment Translation Cart (CETA), the S-band Antenna Assembly, and umbilical cables that provide power and remote operation capability to cameras. During their EVA, they are shown using a foot platform on the robotic arm. Significant portions of their activities are shown from the vantage of helmet mounted video cameras. The video closes with a final shot of the ISS and its new S1 truss.

  20. Understanding genetic toxicity through data mining: the process of building knowledge by integrating multiple genetic toxicity databases. (United States)

    Yang, C; Hasselgren, C H; Boyer, S; Arvidson, K; Aveston, S; Dierkes, P; Benigni, R; Benz, R D; Contrera, J; Kruhlak, N L; Matthews, E J; Han, X; Jaworska, J; Kemper, R A; Rathman, J F; Richard, A M


    ABSTRACT Genetic toxicity data from various sources were integrated into a rigorously designed database using the ToxML schema. The public database sources include the U.S. Food and Drug Administration (FDA) submission data from approved new drug applications, food contact notifications, generally recognized as safe food ingredients, and chemicals from the NTP and CCRIS databases. The data from public sources were then combined with data from private industry according to ToxML criteria. The resulting "integrated" database, enriched in pharmaceuticals, was used for data mining analysis. Structural features describing the database were used to differentiate the chemical spaces of drugs/candidates, food ingredients, and industrial chemicals. In general, structures for drugs/candidates and food ingredients are associated with lower frequencies of mutagenicity and clastogenicity, whereas industrial chemicals as a group contain a much higher proportion of positives. Structural features were selected to analyze endpoint outcomes of the genetic toxicity studies. Although most of the well-known genotoxic carcinogenic alerts were identified, some discrepancies from the classic Ashby-Tennant alerts were observed. Using these influential features as the independent variables, the results of four types of genotoxicity studies were correlated. High Pearson correlations were found between the results of Salmonella mutagenicity and mouse lymphoma assay testing as well as those from in vitro chromosome aberration studies. This paper demonstrates the usefulness of representing a chemical by its structural features and the use of these features to profile a battery of tests rather than relying on a single toxicity test of a given chemical. This paper presents data mining/profiling methods applied in a weight-of-evidence approach to assess potential for genetic toxicity, and to guide the development of intelligent testing strategies.

  1. Burdale: An Anglian Settlement in the Yorkshire Wolds (Data Paper

    Directory of Open Access Journals (Sweden)

    Julian D. Richards


    Full Text Available The Burdale digital archive (Richards and Roskams 2013 comprises a broad range of primary and secondary data derived from fieldwork and post-excavation analysis. It complements the summary report published as Richards and Roskams (2012. Full stratigraphic reports are downloadable for each season of excavation and can be related to the sequence of CAD plans also available. These can, in turn, be set within the wider site map derived from aerial photography and geophysical survey. Final reports are available for the pottery, spindlewhorls, and worked bone and antler (Ashby 2013. Other finds are simply listed in the finds databases, split by excavation year, with some preliminary notes on the ironwork included in the investigative conservation reports. The non-ferrous finds assemblage was largely missing, apart from a small number of topsoil finds recovered during metal detector surveys. Given the alleged wealth of the site, and the interest in it from 'nighthawks' we have to assume that unfortunately, most of the coinage and copper alloy metalwork has been collected from the ploughsoil over many years and is in private hands or has been sold for profit. In common with other Yorkshire sites Burdale produced very little early medieval pottery but this is likely to be a real absence rather than a product of recovery bias. The animal bone assemblage (Richardson 2010 is one of the most important elements of the archive. Over 300 images are also presented, split by year of excavation. The file downloads are organised in 3 groups: those relating to the whole project and those specifically related to excavations in 2006 (BUR06 or 2007 (BUR07. Referee statement by Gabor Thomas

  2. Questions and answers on the Belgian model of integral end-of-life care: experiment? Prototype? : "Eu-euthanasia": the close historical, and evidently synergistic, relationship between palliative care and euthanasia in Belgium: an interview with a doctor involved in the early development of both and two of his successors. (United States)

    Bernheim, Jan L; Distelmans, Wim; Mullie, Arsène; Ashby, Michael A


    This article analyses domestic and foreign reactions to a 2008 report in the British Medical Journal on the complementary and, as argued, synergistic relationship between palliative care and euthanasia in Belgium. The earliest initiators of palliative care in Belgium in the late 1970s held the view that access to proper palliative care was a precondition for euthanasia to be acceptable and that euthanasia and palliative care could, and should, develop together. Advocates of euthanasia including author Jan Bernheim, independent from but together with British expatriates, were among the founders of what was probably the first palliative care service in Europe outside of the United Kingdom. In what has become known as the Belgian model of integral end-of-life care, euthanasia is an available option, also at the end of a palliative care pathway. This approach became the majority view among the wider Belgian public, palliative care workers, other health professionals, and legislators. The legal regulation of euthanasia in 2002 was preceded and followed by a considerable expansion of palliative care services. It is argued that this synergistic development was made possible by public confidence in the health care system and widespread progressive social attitudes that gave rise to a high level of community support for both palliative care and euthanasia. The Belgian model of so-called integral end-of-life care is continuing to evolve, with constant scrutiny of practice and improvements to procedures. It still exhibits several imperfections, for which some solutions are being developed. This article analyses this model by way of answers to a series of questions posed by Journal of Bioethical Inquiry consulting editor Michael Ashby to the Belgian authors.

  3. VizieR Online Data Catalog: Follow-up study of gal. & AGNs in z>1 clusters (Alberts+, 2016) (United States)

    Alberts, S.; Pope, A.; Brodwin, M.; Chung, S. M.; Cybulski, R.; Dey, A.; Eisenhardt, P. R. M.; Galametz, A.; Gonzalez, A. H.; Jannuzi, B. T.; Stanford, S. A.; Snyder, G. F.; Stern, D.; Zeimann, G. R.


    In this work, we concentrate our analysis on 11 spectroscopically confirmed clusters from the IRAC Shallow/Distant Cluster Survey (ISCS/IDCS) that we observed with Herschel/PACS at 100 and 160um, obtained during Open Time 2 observing (PID: OT2apope3) (summary of imaging in table 6 spanning from June 2012 to January 2013). Given the resolution of PACS (FWHM~6.7" at 100um and 11" at 160um), we expect the majority of sources and all cluster galaxies in our maps to be point sources. See sections 2.1 and 2.3 for further details. The IRAC Shallow Survey (ISS) was followed up with three more observations as part of SDWFS (Ashby et al. 2009, see J/ApJ/716/530), providing a factor of 2 deeper IRAC catalog with an aperture-corrected 5σ limit of 5.2uJy at 4.5um ([4.5]=18.83mag). Spitzer/MIPS observations are available from the MIPS AGM and Galaxy Evolution Survey (MAGES; Jannuzi et al. 2010AAS...21547001J). See section 2.4 for further details. Targeted follow up campaigns by our group have obtained spectroscopic redshifts for galaxies and AGNs in z>1 clusters using multi-object Keck optical spectroscopy and Wide Field Camera 3 (WFC3) slitless NIR grism spectroscopy from the Hubble Space Telescope (HST). The reader is directed to Brodwin et al. (2013ApJ...779..138B), Zeimann et al. (2013, J/ApJ/779/137), and references therein for a detailed description of the targeted spectroscopy. Some spectroscopic redshifts are additionally provided by the AGN and Galaxy Evolution Survey (AGES; Kochanek et al. 2012, J/ApJS/200/8). See section 2.2. (3 data files).

  4. Reward and punishment effects on error processing and conflict control

    Directory of Open Access Journals (Sweden)

    Birgit eStürmer


    Full Text Available Recently, positive mood has been shown to reduce cognitive conflicts and adaptation related to conflict control. Van Steenbergen et al. (2009 proposed that short-term adaptation after conflict is driven by the aversive quality of the conflict. They reasoned that monetary gain and its positive emotional consequences might counteract the aversive quality of the preceding conflict and hence reduce subsequent conflict-driven adaptation processes. According to Ashby et al. (1999, however, positive affect increases cognitive flexibility and might, therefore, support cognitive conflict control.In two experiments, we combined Simon-type conflicts with monetary gains and losses in between trials and analyzed event-related brain potentials (ERPs. In Experiment 1 gains and losses were applied randomly as a lottery in between two Simon trials whereas in the second experiment gains and losses were related to behavioral performance. Either the 25 % fastest responses were rewarded or the 25 % slowest responses were penalized. In Experiment 1 conflict adaptation was not at all modulated by gains and losses and in Experiment 2 conflict adaptation increased after a gain. In addition we analyzed the error-related negativity (ERN in Experiment 2 – a brain signal proposed to be related to the reward prediction error and response conflicts. The ERN and post-error slowing were enlarged in the context of reward. We conclude that a context of reward increases the subjective value of an error, thus, enhancing error adaptation. However, modulatory effects of affective states on cognitive conflict control are much more limited as previously asserted.

  5. Adaptive and Rational Anticipations in Risk Management Systems and Economy (United States)

    Dubois, Daniel M.; Holmberg, Stig C.


    The global financial crisis of year 2009 is explained as a result of uncoordinated risk management decisions in business firms and economic organisations. The underlying reason for this can be found in the current financial system. As the financial market has lost much of its direct coupling to the concrete economy it provides misleading information to economic decision makers at all levels. Hence, the financial system has moved from a state of moderate and slow cyclical fluctuations into a state of fast and chaotic ones. Those misleading decisions can further be described, but not explained, by help of adaptive and rational expectations from macroeconomic theory. In this context, AE, the Adaptive Expectations are related to weak passive Exo-anticipation, and RE, the Rational expectations can be related to a strong, active and design oriented anticipation. The shortcomings of conventional cures, which builds on a reactive paradigm, have already been demonstrated in economic literature and are here further underlined by help of Ashby's "Law of Requisite Variety", Weaver's distinction between systems of "Disorganized Complexity" and those of "Organized Complexity", and Klir's "Reconstructability Analysis". Anticipatory decision-making is hence here proposed as a replacement to current expectation based and passive risk management. An anticipatory model of the business cycle is presented for supporting that proposition. The model, which is an extension of the Kaldor-Kalecki model, includes both retardation and anticipation. While cybernetics with the feedback process in control system deals with an explicit goal or purpose given to a system, the anticipatory system discussed here deals with a behaviour for which the future state of the system is built by the system itself, without explicit goal. A system with weak anticipation is based on a predictive model of the system, while a system with strong anticipation builds its own future by itself. Numerical simulations on

  6. 当代英国女性诗人及其群体研究综述

    Institute of Scientific and Technical Information of China (English)



    国外对当代女性诗人研究的状况调查20世纪80年代以后,英国诗坛真正响起女性的声音,她们的影响甚至超过了男性.当代女性诗人代表人物主要有:海伦·丹默(Helen Dunmore)、卡罗·鲁门斯(Carol Rumens)、珊米玛·希尔(Selima Hill)、卡罗·安·达菲(Carol Ann Duffy)、西尔维娅·普拉斯( Sylvia Plath)、伊丽莎白·简宁斯(Elizabeth Jennings)、杰琪·凯(Jackie Kay)、乔·夏普可特(Jo Shapcott)等.她们均受过良好的教育,有强烈的主体意识和自觉意识,追求个性的解放和社会、文化身份的认同.与此同时,女性诗歌研究在英国文坛受到重视,出现了不少重要的相关著作.1985年,著名的布勒戴克斯公司出版发行了《当代女诗人——十一位英国作家》(The Bloodaxe Book of Contemporary Women Poets:Eleven British Writers)一书,之后又连续再版九次,对当代诗坛产生了巨大影响.2002年,曼彻斯特大学出版社出版了由詹·蒙特菲奥里(Jan Montefiore)编著的《心灵和精神的论争:1977-2000年论文选集》 (Arguments of Heart and Mind:Selected Essays,1977-2000)一书.此书立足于女性主义批评视角,收录了1977-2000年期间有关探讨女性身份、性别及女性写作传统等的优秀文章.2003年,布勒戴克斯出版社为庆祝建社二十五周年特别出版了诗集《诗歌年度选集2003》.这部诗集共收录了二十五位当代最有影响力、最有代表性的诗人作品,其中女诗人十四人,超过了半数.2005年,剑桥大学出版了由简·道森(Jane Dowson)和艾里斯·恩特威斯尔(Alice Entwistle)共同编著的《二十世纪英国女性诗歌历史》(A History Of Twentieth-Century British Women's Poetry)一书.书中第三部分"1980-2000年诗歌回顾"中特别关注了卡罗.安.达菲、卡罗·鲁门斯及杰琪·凯的诗歌创作.2007年,剑桥大学再次出版发行了由尼尔·柯克兰( Neil Corcoran)编著的《剑桥二

  7. The Time Is Now: Bioethics and LGBT Issues. (United States)

    Powell, Tia; Foglia, Mary Beth


    disparities. Stephan Davis and Nancy Berlinger assess the challenges of access to care and health policy for transgender persons. Edward J. Callahan et al. tackle the ways in which diverse aspects of medicine should change to better incorporate the needs of LGBT patients, including through use of the electronic medical record, education of health professionals, and recruitment efforts for LGBT health professionals. Virginia Ashby Sharpe and Uchenna S. Uchendu describe multifaceted efforts within Veterans Administration facilities to create change for LGBT veterans across the largest integrated health care network in the United States. Lance Wahlert and Autumn Fiester find a mixed record in the use of case studies in teaching about LGBT issues.

  8. Hierarchies of description of energy systems ИЕРАРХИИ ПРЕДСТАВЛЕНИЯ ЭНЕРГЕТИЧЕСКИХ СИСТЕМ

    Directory of Open Access Journals (Sweden)

    Volkov Andrey Anatol'evich


    Full Text Available The author considers one of the most important tasks to be tackled in the course of modeling of processes or phenomena, that is, identification of the degree of detail of a description. It is also applicable to energy systems and their efficiency. This task has a particular significance as any researcher needs to attribute names to the system elements and their states. This discussion originates from the basic provisions of the Ashby principles and fundamentals of the modeling of information systems in the realm of generalized states, or situations. A model should take a proper account of the fact that some information is lost whenever more detailed level of description is replaced by the less detailed one. Thus, the task consists in the hierarchical description of functioning systems. We introduce the hyper-system model to solve this task.The mathematical theory set forth in the paper proves that any losses of information about some object are inevitable whenever the level of description is changed. One may see new logical and mathematical problems arising in this field. For example, there is still no answer to the question how “deep” we can advance in our studies of hierarchical systems.Затронут вопрос, касающийся моделирования энергетических систем и их эффективности. Описан подход к решению задачи об иерархическом представлении функционирующих систем, базирующийся на модели гиперсистемы.

  9. 周期性多孔材料等效杨氏模量的尺度效应研究

    Institute of Scientific and Technical Information of China (English)

    戴高明; 张卫红


    随着航空航天与民用技术对多孔材料应用的广泛需求,对于该种轻质材料的研究达到了空前的高度.该文着重研究了周期性多孔材料等效杨氏模量的有效计算方法,在综合分析现有均匀化方法,G-A(Gibson and Ashby)细观力学方法、拉伸能量法无法反映体胞尺寸效应的基础上,提出了弯曲能量新方法,并对4种方法的预测效果进行了系统的研究,揭示了弯曲能量法的通用性、尺寸效应的预测能力以及与4种方法的内在联系与差异.以拉伸和弯曲两种力学加载模型的有限元数值计算结果以及文献给出的六边形蜂窝实测实验结果为基准,比较分析了4种方法在预测拉伸变形和弯曲挠度的计算精度.结果表明,弯曲能量法能很好地预测不同构型蜂窝单胞的等效杨氏模量及其尺寸效应,并能很好反映不同加载模式下结构变形随多孔材料体胞尺寸的变化规律包括六边形蜂窝的非单调变化趋势,而其他3种方法仅能预测体胞无限小时的极限结果.

  10. The strength of heterogeneous volcanic rocks: A 2D approximation (United States)

    Heap, Michael J.; Wadsworth, Fabian B.; Xu, Tao; Chen, Chong-feng; Tang, Chun'an


    Volcanic rocks typically contain heterogeneities in the form of crystals and pores. We investigate here the influence of such heterogeneity on the strength of volcanic rocks using an elastic damage mechanics model in which we numerically deform two-dimensional samples comprising low-strength elements representing crystals and zero-strength elements representing pores. These circular elements are stochastically generated so that there is no overlap in a medium representing the groundmass. Our modelling indicates that increasing the fraction of pores and/or crystals reduces the strength of volcanic rocks, and that increasing the pore fraction results in larger strength reductions than increasing the crystal fraction. The model also highlights an important weakening role for pore diameter, but finds that crystal diameter has a less significant influence for strength. To account for heterogeneity (pores and crystals), we propose an effective medium approach where we define an effective pore fraction ϕp‧ = Vp/(Vp + Vg) where Vp and Vg are the pore and groundmass fractions, respectively. Highly heterogeneous samples (containing high pore and/or crystal fractions) will therefore have high values of ϕp‧, and vice-versa. When we express our numerical samples (more than 200 simulations spanning a wide range of crystal and pore fractions) in terms of ϕp‧, we find that their strengths can be described by a single curve for a given pore diameter. To provide a predictive tool for the strength of heterogeneous volcanic rocks, we propose a modified version of 2D solution for the Sammis and Ashby (1986) pore-emanating crack model, a micromechanical model designed to estimate strength using microstructural attributes such as porosity, pore radius, and fracture toughness. The model, reformulated to include ϕp‧ (and therefore crystal fraction), captures the strength curves for our numerical simulations over a sample heterogeneity range relevant to volcanic systems. We find

  11. 镁基多孔材料准静态压缩行为与吸能特性研究%The Quasi-static Compressive Behavior and Energy Absorption Properties of Mg-based Porous Materials

    Institute of Scientific and Technical Information of China (English)

    郝刚领; 韩福生; 王伟国


    基于可去除填充颗粒的粉末冶金技术制备了孔隙率在40%~80%,孔径在1~2mm内变化的多孔镁和多孔AZ91D镁合金,并系统考察了材料的准静压压缩行为和吸能特性.结果发现,镁基多孔材料的压缩应力-应变曲线由线性弹性区、平台和致密化区域组成,但曲线锯齿状波动较大,表明材料的脆性断裂机制.压缩屈服强度与相对密度的关系可通过Gibson-Ashby模型来理解,但屈服强度对孔径的依赖性较低.吸能本领随相对密度的增加而增加,相同条件下,多孔AZ91D镁合金的吸能本领高于多孔镁,多孔镁的吸能效率则高于多孔AZ91D镁合金.%Porous Mg and porous AZ91D alloy were prepared using powder metallurgy method basing on space holding fillers. The porosity and pore size can be controlled in the range of 40%-80% and 0. 5-2. 0mm respectively. The investigation was carried out on the quasi-static compressive behavior and energy absorption properties of the Mg-based porous materials. The result shows that the compressive stress-strain curves were consisted of linear elastic region, plateau and densification region. The plateau region is serrated which indicates a brittle deformation mechanism. The dependence of yield strength on relative density can be understood in terms of Gibson-Ashby model, but the effect of pore size is small that can be neglectable. The energy absorption capacity of the Mg-based porous materials increases with the relative density increasing. Porous AZ91D alloy at the same conditions exhibits a higher energy absorption capacity than the porous Mg, that however represents a higher energy absorption efficiency than the porous AZ91D alloy.

  12. 不同孔径分布多孔钛的力学性能%Mechanical properties of porous titanium with different distributions of pore size

    Institute of Scientific and Technical Information of China (English)

    王晓花; 李金山; 胡锐; 寇宏超; 周廉


    从生物学角度出发设计并制备2种不同孔径分布的多孔钛,并研究其力学性能。采用造孔剂烧结方法制备孔隙率为36%~63%的多孔钛,通过室温压缩测试其力学性能。多孔钛的弹性模量和抗压强度分别在2.662~18 GPa和94.05~468.57 MPa范围内,且都随着孔隙率的增加而降低。抗压强度和孔隙率的关系曲线呈现完全的线性特征,表明抗压强度主要受孔隙率的影响,几乎不受孔径的影响。Gibson-Ashby力学关系分析结果显示:常数项C值的差异说明孔径分布对多孔钛的屈服强度有一定的影响;密度指数n值均大于临界值3,表明这2种不同孔径的多孔钛的变形方式相同,为孔壁的屈曲作用。%To satisfy the mechanical and biological requirement of porous bone substitutes, porous Ti with two different pore sizes designed in advance was fabricated by the space-holder sintering process. Mechanical properties of the porous Ti were explored via room temperature compressive tests. The pore sizes and shapes are uniform throughout the specimens with porosities ranging from 36%to 63%. The compression strength and the elastic modulus are in the range from 94.05 to 468.57 MPa and 2.662 to 18 GPa, respectively. It is worth noting that the relationship between the compressive strength and the porosities is completely linear relation beyond the effect of pore size distributions on the mechanical properties. The value of the constant C achieved from the Gibson-Ashby model suggests that the pore sizes affect the yield strength of the porous Ti and the values of density exponent (n) for porous Ti with two different pore sizes are higher than 2, which suggests that the deformation mode of the porous Ti with a porosity ranging from 36%to 63%is mainly buckling of the cell struts.

  13. Consolidation of nanostructured metal powders by rapid forging: Processing, modeling, and subsequent mechanical behavior (United States)

    Shaik, G. R.; Milligan, W. W.


    Fe-10Cu powders containing 20-nm grains were produced by attritor milling of elemental powders in argon. A rapid powder forging technique was developed to consolidate the powders into fully dense compacts while maintaining nanoscale grain sizes. Grain growth during the consolidation was controlled by reducing the time of exposure at elevated temperature to a few minutes or less, a technique which is applicable to all materials and does not necessitate the addition of dispersoids. This was achieved by heating green compacts quickly using an induction heater, and then forging and rapidly cooling them back to room temperature. Forging was conducted in a protective argon atmosphere to limit contamination. Fully dense compacts were produced at relatively low temperatures, mainly due to the accelerated creep rates exhibited by the nanostructures. Transmission electron microscopy and X-ray diffraction analysis found an average grain size of 45 nm in the fully dense samples forged at 530°C. Indications are that finer grain sizes should be attainable by using slightly lower temperatures and higher pressures. The success of the technique (compared to hot-isostatic pressing (“hipping”)) is due to both reducing time at elevated temperatures and applying relatively high pressures. Microhardness tests revealed a significant strengthening effect due to grain size refinement, following a Hall-Petch relation. Compression testing at room temperature showed no strain hardening during plastic deformation, which occurred by shear banding. High strengths, up to 1800 MPa, were obtained at room temperature. Compression testing at 575°C revealed a significant strain rate dependence of mechanical behavior and also the possibility of superplastic behavior. Power-law creep was observed at 575°C, with very high steady-state creep rates on the order of 50 pct/s at 230 MPa. The consolidation process was successfully modeled by slightly modifying and applying the Arzt, Ashby, and

  14. Working with "rookies": A case study of science teachers mentors (United States)

    Meagher, Thomas Francis

    To gain insight into the world of mentoring new science teachers it is imperative to examine how a veteran science teacher is influenced through his or her work mentoring a new teacher. The impacts of mentoring new teachers have been extensively researched within the literature, documenting many of the factors that may enhance the teaching abilities of new teachers (Hobson, Ashby, Malderez & Tomlinson, 2008; Ingersoll & Kralik, 2004; Wang & Odell, 2002). A thorough search of the literature reveals an unbalanced representation of research focusing on the many influences mentoring may bring to a new teacher while ignoring the impact on the mentor. It is when the activity of mentoring a new teacher is examined within the theoretical frame work of social cognitive learning, it is apparent that not only are two individuals participating in working together, but also that research needs to investigate both sides of the relationship. Also, since the mentoring relationship is situated within a community of practice, it becomes important to utilize a situated learning theoretical framework in tandem with social cognitive learning to provide the clearest picture of this dynamic social relationship. This case study seeks to share the impacts experienced by mentors through their work with new teachers and provide balance to the other side of research into the social partnership of mentoring. Five science teachers mentoring new teachers online, through the University of Minnesota's Science Engineering, Math Mentoring Program (STEMMP) and Science Teacher Induction Network (TIN), participated in this study that explores their experiences through a phenomenographic lens and follows an interpretive research approach. Four main themes emerged that identified how science teacher mentors were impacted from mentoring which included: (1) impacts to their teaching practice, (2) perceptions influenced from feedback, (3) enhanced reflection, and (4) enhancement of self-efficacy. The

  15. NASA Managers Set July 20 As Launch Date for Chandra Telescope (United States)


    NASA managers set Tuesday, July 20, 1999, as the official launch date for NASA's second Space Shuttle Mission of the year that will mark the launch of the first female Shuttle Commander and the Chandra X-Ray Observatory. Columbia is scheduled to liftoff from Launch Pad 39-B at the Kennedy Space Center on July 20 at the opening of a 46-minute launch window at 12:36 a.m. EDT. Columbia's planned five-day mission is scheduled to end with a night landing at the Kennedy Space Center just after 11:30 p.m. EDT on July 24. Following its deployment from the Shuttle, Chandra will join the Hubble Space Telescope and the Compton Gamma Ray Observatory as the next in NASA's series of "Great Observatories." Chandra will spend at least five years in a highly elliptical orbit which will carry it one-third of the way to the moon to observe invisible and often violent realms of the cosmos containing some of the most intriguing mysteries in astronomy ranging from comets in our solar system to quasars at the edge of the universe. Columbia's 26th flight is led by Air Force Col. Eileen Collins, who will command a Space Shuttle mission following two previous flights as a pilot. The STS-93 Pilot is Navy Captain Jeff Ashby who will be making his first flight into space. The three mission specialists for the flight are: Air Force Lt. Col. Catherine "Cady" Coleman, who will be making her second flight into space; Steven A. Hawley, Ph.D, making his fifth flight; and French Air Force Col. Michel Tognini of the French Space Agency (CNES), who is making his first Space Shuttle flight and second trip into space after spending two weeks on the Mir Space Station as a visiting cosmonaut in 1992. NASA press releases and other information are available automatically by sending an Internet electronic mail message to In the body of the message (not the subject line) users should type the words "subscribe press-release" (no quotes). The system will reply with a confirmation via E-mail of

  16. Void growth in metals: Atomistic calculations

    Energy Technology Data Exchange (ETDEWEB)

    Traiviratana, Sirirat [Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA 92093 (United States); Bringa, Eduardo M. [Materials Science Department, Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Benson, David J. [Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA 92093 (United States); Meyers, Marc A. [Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA 92093 (United States); NanoEngineering, University of California, San Diego, La Jolla, CA 92093 (United States)], E-mail:


    Molecular dynamics simulations in monocrystalline and bicrystalline copper were carried out with LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) to reveal void growth mechanisms. The specimens were subjected to tensile uniaxial strains; the results confirm that the emission of (shear) loops is the primary mechanism of void growth. It is observed that many of these shear loops develop along two slip planes (and not one, as previously thought), in a heretofore unidentified mechanism of cooperative growth. The emission of dislocations from voids is the first stage, and their reaction and interaction is the second stage. These loops, forming initially on different {l_brace}1 1 1{r_brace} planes, join at the intersection, if the Burgers vector of the dislocations is parallel to the intersection of two {l_brace}1 1 1{r_brace} planes: a <1 1 0> direction. Thus, the two dislocations cancel at the intersection and a biplanar shear loop is formed. The expansion of the loops and their cross slip leads to the severely work-hardened region surrounding a growing void. Calculations were carried out on voids with different sizes, and a size dependence of the stress threshold to emit dislocations was obtained by MD, in disagreement with the Gurson model which is scale independent. This disagreement is most marked for the nanometer sized voids. The scale dependence of the stress required to grow voids is interpreted in terms of the decreasing availability of optimally oriented shear planes and increased stress required to nucleate shear loops as the void size is reduced. The growth of voids simulated by MD is compared with the Cocks-Ashby constitutive model and significant agreement is found. The density of geometrically necessary dislocations as a function of void size is calculated based on the emission of shear loops and their outward propagation. Calculations are also carried out for a void at the interface between two grains to simulate polycrystalline

  17. Microwave-assisted synthesis, crystal structure and toxicity of L-aspartic acid zinc spiral linear supramolecular polymer

    Institute of Scientific and Technical Information of China (English)

    ZHANG; Youming; LIN; Qi; WEI; Taibao


    [1]Prasad, A.S. Nutritional metabolic role of zinc, Fed. Proc., 1967,26(1): 172-185.[2]Slagueiro, M. J., Zubillaga, M. B., Lysionek, A. E. et al., The role of zinc in the growth and development of children, Nutrition,2002, 18: 510-519.[3]Mossad, S. B., Zinc and the common cold: Are we close to a true?Nutrition, 1997, 13: 708-709.[4]Prasad, A. S., Clinical and biochemical manifestations of zinc deficiency in human subjects, J. Am. Coll. Nutr., 1985, 4(1):73-82.[5]Prasad, A. S., Zinc deficiency in sickle cell disease, Prog. Clin.Biol. Res., 1984, 165: 49-58.[6]Prasad, A. S., Discovery of zinc deficiency: Impact on human health, Nutrition, 2001, 17: 685-687.[7]Gao, S. -L., Fan, Y., Hu, R. -Z. et al., Synthesis, properties and phase equilibrian of Zn(NO3)2-Leu-H2O system (25℃), Chem. J.Chinese Universities (in Chinese), 2003, 24(2): 195-199.[8]Viladkar, S., Kamaluddin, Nath, M., Hydrolysis of phosphate by (amino acidato)zinc complexes, Bull. Chem. Soc. Jpn., 1993,66(10): 2922-2926.[9]Ashby, C. I. H., Paton, W. F., Brown, T. L., Nitrogen-14 nuclear quadrupole resonance spectra of the coordinated amino group and of coordinated imidazole. Crystal and molecular structures of chloroglycylglycinato(imidazole)cadmium, J. Am. Chem. Soc.,1980, 102(9): 2990-2998.[10]Jia, D. -Z., Yang, L. -X., Xia, X. et al., Studies on application of microwave heating techniques for the solid state reactions of coordination Compounds (Ⅰ), Chem. J. Chinese Universities (in Chinese), 1997, 18(9): 1432-1435.[11]Lidstrom, P., Tierney, J., Wathey, B. et al., Microwave assisted organic synthesis-a review, Tetrahedron, 2001, 57: 9925-9283.[12]Zhang, Y. M., Bai, J. F., Lu, M. Q. et al., Preparation of amino-acid Zinc and its character, Huaxue Shijie (in Chinese),1997, (2): 82-84.

  18. Carbon nanotube-copper exhibiting metal-like thermal conductivity and silicon-like thermal expansion for efficient cooling of electronics. (United States)

    Subramaniam, Chandramouli; Yasuda, Yuzuri; Takeya, Satoshi; Ata, Seisuke; Nishizawa, Ayumi; Futaba, Don; Yamada, Takeo; Hata, Kenji


    Increasing functional complexity and dimensional compactness of electronic devices have led to progressively higher power dissipation, mainly in the form of heat. Overheating of semiconductor-based electronics has been the primary reason for their failure. Such failures originate at the interface of the heat sink (commonly Cu and Al) and the substrate (silicon) due to the large mismatch in thermal expansion coefficients (∼300%) of metals and silicon. Therefore, the effective cooling of such electronics demands a material with both high thermal conductivity and a similar coefficient of thermal expansion (CTE) to silicon. Addressing this demand, we have developed a carbon nanotube-copper (CNT-Cu) composite with high metallic thermal conductivity (395 W m(-1) K(-1)) and a low, silicon-like CTE (5.0 ppm K(-1)). The thermal conductivity was identical to that of Cu (400 W m(-1) K(-1)) and higher than those of most metals (Ti, Al, Au). Importantly, the CTE mismatch between CNT-Cu and silicon was only ∼10%, meaning an excellent compatibility. The seamless integration of CNTs and Cu was achieved through a unique two-stage electrodeposition approach to create an extensive and continuous interface between the Cu and CNTs. This allowed for thermal contributions from both Cu and CNTs, resulting in high thermal conductivity. Simultaneously, the high volume fraction of CNTs balanced the thermal expansion of Cu, accounting for the low CTE of the CNT-Cu composite. The experimental observations were in good quantitative concurrence with the theoretically described 'matrix-bubble' model. Further, we demonstrated identical in-situ thermal strain behaviour of the CNT-Cu composite to Si-based dielectrics, thereby generating the least interfacial thermal strain. This unique combination of properties places CNT-Cu as an isolated spot in an Ashby map of thermal conductivity and CTE. Finally, the CNT-Cu composite exhibited the greatest stability to temperature as indicated by its low

  19. Carbon Sequestration on Surface Mine Lands

    Energy Technology Data Exchange (ETDEWEB)

    Donald Graves; Christopher Barton; Richard Sweigard; Richard Warner; Carmen Agouridis


    Since the implementation of the federal Surface Mining Control and Reclamation Act of 1977 (SMCRA) in May of 1978, many opportunities have been lost for the reforestation of surface mines in the eastern United States. Research has shown that excessive compaction of spoil material in the backfilling and grading process is the biggest impediment to the establishment of productive forests as a post-mining land use (Ashby, 1998, Burger et al., 1994, Graves et al., 2000). Stability of mine sites was a prominent concern among regulators and mine operators in the years immediately following the implementation of SMCRA. These concerns resulted in the highly compacted, flatly graded, and consequently unproductive spoils of the early post-SMCRA era. However, there is nothing in the regulations that requires mine sites to be overly compacted as long as stability is achieved. It has been cultural barriers and not regulatory barriers that have contributed to the failure of reforestation efforts under the federal law over the past 27 years. Efforts to change the perception that the federal law and regulations impede effective reforestation techniques and interfere with bond release must be implemented. Demonstration of techniques that lead to the successful reforestation of surface mines is one such method that can be used to change perceptions and protect the forest ecosystems that were indigenous to these areas prior to mining. The University of Kentucky initiated a large-scale reforestation effort to address regulatory and cultural impediments to forest reclamation in 2003. During the three years of this project 383,000 trees were planted on over 556 acres in different physiographic areas of Kentucky (Table 1, Figure 1). Species used for the project were similar to those that existed on the sites before mining was initiated (Table 2). A monitoring program was undertaken to evaluate growth and survival of the planted species as a function of spoil characteristics and

  20. Questions and Answers on the Belgian Model of Integral End-of-Life Care:Experiment Prototype%临终关怀与安乐死的整合:比利时模式的实验与回答

    Institute of Scientific and Technical Information of China (English)

    Jan L. Bernheim; Wim Distelmans; Arsène Mullie; Michael A. Ashby; 于磊(译)


    通过《生命伦理学探究杂志》顾问编辑Michael Ashby提出的一系列问题对比利时临终照护模式的构成进行分析。分析了关于比利时姑息治疗与安乐死之间互补及协同关系。在比利时模式的整合临终护理中,安乐死是姑息治疗途径的终点。安乐死合法化制定于2002年,而后,众多姑息治疗服务兴起。随着公众对卫生保健机构信心的提升和社会态度的广泛进步,对姑息治疗和安乐死的支持水平明显提高,这将使二者的协同发展成为可能。虽然目前比利时模式仍表现出一些缺陷,但一些解决方案正在制定过程中。%This article analyzed the Belgian model of integral end‐of‐life care by way of answering to a series of questions posed by Journal of Bioethical Inquiry consulting editor Michael Ashby to the Belgian authors .The complementary and synergistic relationship between palliative care and euthanasia in Belgium were discussed .In what has become known as the Belgian model of integral end‐of‐life care ,euthanasia is an available option ,also at the end of a palliative care pathway .The legal regulation of euthanasia in 2002 was preceded and followed by a considerable expansion of palliative care services .It is argued that this synergistic development was made possible by public confidence in the health care system and widespread progressive social attitudes that gave rise to a high level of community support for both palliative care and euthanasia .It still exhibits several imperfections ,for which some solutions are being developed .

  1. 山西黄芪根际固氮菌的分离与应用%Isolation and application of nitrogen-fixing bacteria in rhizosphere of Astragalus membranaceus Bunge in Shanxi

    Institute of Scientific and Technical Information of China (English)

    薛智权; 唐中伟; 李浩; 周然; 梁建萍


    [Objective]Astragalus membranaceus Bunge (AMB)is an important herb that has been used in traditional Chinese medicine for centuries,and Hunyuan County of Shanxi province is one of the most important planting bases for AMB.Nitrogen fertilizer input for AMB production in China is very high.It is essential to reduce nitrogen fertilizer in-put and thus cultivation cost while achieving a high yield for sustainable and environmentally friendly AMB production. Research on biological nitrogen fixation has increased significantly because of its potential importance to the economy and the environment.AMB plants can obtain nitrogen from biological nitrogen fixation via diazotrophs.The aim of this work was to screen and identify nitrogen-fixing bacteria from the rhizosphere of AMB cultivated in Hunyuan County, Shanxi province,and to demonstrate their potential for nitrogen fixation with AMB as well as plant growth promotion. [Methods]120 nitrogen fixing strains were isolated from soil samples using Ashby nitrogen free medium.Two strains of them,t1 6 and t21,with strong ability of nitrogen fixation were screened out according to the ability of nitrogen fixa-tion,growth speed and other characteristics in further screening with nitrogen fixing medium.To demonstrate their potential for nitrogen fixation with AMB and growth promotion activities,the bacterial liquid of the two isolates were used to soak AMB seeds and inoculate into AMB seedlings for 30 d at 28°C in a growth cabinet.[Results]Based on morphological detection,physiological and biochemical detection and 1 6S rRNA gene sequence analysis,the two strains of t1 6 and t21 were identified as Rhizobium sp.and Sinorhizobium sp.,respectively.Both of the two strains signifi-cantly promoted the growth of AMB seedlings.They also increased the nitrogen contents of dry weight by 14.23% to 18.67% and 13.10% to 18.77%,respectively,compared with the uninoculated controls.The bacterial liquids of T1 6 with 10 6 mL-1 and T21 with 10 8 m

  2. Selección y caracterización de rizobacterias promotoras de crecimiento vegetal (RPCV asociadas al cultivo de algodón (Gossypium hirsutum

    Directory of Open Access Journals (Sweden)

    Andrés Guzmán


    Full Text Available Normal 0 21 false false false ES-CO X-NONE X-NONE MicrosoftInternetExplorer4 Título en ingles: Selection and characterization of plant growth promoting rhizobacteria (PGPR’s associated with cotton crop (Gossypium hirsutum Resumen: Como parte de las estrategias de una agricultura sostenible, se hace necesario disminuir el uso de fertilizantes nitrogenados de síntesis, mediante la utilización de los biofertilizantes. En particular, los géneros Azotobacter y Azospirillum son utilizados como agentes promotores de crecimiento vegetal debido a su capacidad para fijar nitrógeno atmosférico y producir hormonas de tipo indólico. Por tal razón, en este estudio se aislaron bacterias diazotróficas de los géneros Azotobacter y Azospirillum a partir de la rizósfera de cultivos de algodón en el Espinal (Tolima. Las poblaciones microbianas se caracterizaron fenotípicamente en los medios de cultivo semiespecíficos: Ashby y LG (Azotobacter sp. y NFb, LGI y Batata (Azospirillum sp.. La promoción de crecimiento vegetal se determinó mediante la actividad de la enzima nitrogenasa por medio de la técnica de reducción de acetileno y producción de índoles por el método colorimétrico de Salkowsky. Se obtuvieron 9 aislamientos tentativos de Azotobacter sp. y 4 de Azospirillum sp. Se presentaron diferencias significativas en la prueba de reducción de acetileno con las cepas presuntivas de Azotobacter sp.: NAT 9 (206.43 nmol C2H2 mL-1.h-1, NAT 4, (292.77 nmol C2H2 mL-1.h-1, y NAT 6 (460.60 nmol C2H2 mL-1.h-1 y en la producción de índoles de las cepas NAT 19 (19.87 μg.mL-1 y NAT 13 (20.08 μg.mL-1. Por su eficiencia in vitro en la promoción de crecimiento vegetal se seleccionaron las cepas NAT9, NAT4, NAT6, NAT19 y NAT13 para ser evaluadas como principio activo en futuros inoculantes para el algodón en esta zona del departamento del Tolima. Palabras clave: fijación biológica de nitrógeno; producción de índoles; promoción del crecimiento

  3. Six-year-old Children's Ability on Category Learning: Category Representation, Attention and Learning Strategy%6岁儿童的类别学习能力:类别表征、注意和分类策略

    Institute of Scientific and Technical Information of China (English)

    刘志雅; 宋晓红; Carol A. Seger


    探讨了6岁儿童的类别学习能力、类别表征和分类策略.62名儿童参加了实验,实验1采用了“5/4模型”类别结构,实验2采用了“3/3类别结构”.结果发现:6岁儿童已经具备了一定的类别学习能力;相对于原制表征,6岁儿童更倾向于进行样例表征;6岁儿童在注意上具有定位在高典型性特征维度上的能力,但不具备定位在区分性特征维度上的能力;在类别学习策略上主要采用单维度分类策略和规则加例外的分类策略.%This paper explores 6-year-old children's category representation and learning strategies. Category learning is a fundamental ability through which human beings acquire and organize new knowledge about the world (Ashby, 2005), and is critical for normal cognitive development. There are three major theories or models of how categories are represented: Rule-based, Prototype-based, and Exemplar-based models. Rule-based models assume that category learning is a process of discovering an explicit rule to maximize accuracy (Ashby, 200S; Seger, 2006). Prototype-based models assume that stimuli are categorized on the basis of their similarity to category prototypes stored in memory (Rosch & Mervis, 1975; Smith, Chapman, & Redford, 2010; Coutinho, Redford, & Smith, 2010). A category prototype is generally defined as the average, or most typical, member of a category. Exemplar-based models assume that the categorization of a new exemplar is based on the similarity of the new exemplar to the representations of all previously encountered exemplars stored in memory (Medin & Schaffer, 1978; Kruschke, 1992; Nosofsky, 1992).Previous studies suggest that 6-year-old children have developed some ability to use category knowledge to solve problems (Wilburn & Feeney, 2008; Sloutsky & Lo, 1999; Sloutsky & Fisher, 2001). Furthermore, several critical aspects of category learning are acquired at this age. Fang, Fang, & Xi (1991) pointed out that 6-year-old is a

  4. Prediction during sentence comprehension in aphasia

    Directory of Open Access Journals (Sweden)

    Michael Walsh Dickey


    either highly predictable or unpredictable (Before warming the milk/To prevent a mess, the babysitter took out/checked the …. The PWA varied widely in their verbal fluency, as measured by their verbal-fluency scores on the Comprehensive Aphasia Test (Swinburn, et al., 2004; verbal fluency T-score range: 43-71. Reading times at the critical word (bottle/diaper; see Figure 1 showed a large effect of predictability, with both high- and low-frequency words being read faster in constraining sentence contexts (F[1,7]=13.66, p.1. This pattern is different from findings for older and younger unimpaired adults, who show similar-sized effects for predictability and frequency (Rayner, et al., 2004; Ashby, et al., 2005; Rayner, et al., 2006. However, it is consistent with previous results for aphasia, where effects of word frequency are often missing (e.g., DeDe, 2012. There was no relationship between verbal fluency and the size of the predictability effect (r=.06, p>.4. These findings indicate that PWA can show very robust prediction in comprehension, at least for constraining sentence contexts (Federmeier, 2007. However, prediction appears to be dissociated from variation in verbal fluency/language-production impairment. This finding casts doubt on theories which ground prediction in comprehension in the language production system (Federmeier, 2007; Pickering & Garrod, 2013; Dell & Chang, 2014.


    Institute of Scientific and Technical Information of China (English)

    晏红梅; 余同希; 周风华


    对颗粒聚苯乙烯(EPS)泡沫单粒及封闭容器中的大量颗粒整体分别进行了不同加载速率下的准静态压缩实验,获得相应的压缩应力应变曲线.分析了单颗泡沫颗粒内部气体对材料压缩性能的影响,以及大量颗粒用作包装材料时由于内、外部气体被挤出所引起的密度变化对整体应力应变关系的影响.研究表明:EPS泡沫是典型的闭胞材料,单颗颗粒内部气体压力对材料力学行为的影响可以用Ashby等提出的闭胞材料内部气体压力贡献来描述,经过对实验数据拟合,给出了描述单颗材料的考虑颗粒内部封闭气体压力贡献及加载速率影响的本构方程.另一方面,封闭容器里的大量泡沫颗粒的整体力学性能既受颗粒内部气体压力影响,又受颗粒间缝隙气体流动的影响;表观上这种内、外部气体的贡献可以通过材料的表观密度来描述.通过引入整体密度影响因子,定量分析了加载速率对大量颗粒整体的应力应变关系的影响.研究结果对理解大量泡沫颗粒整体的力学性能提供一定的线索.%In this paper,we examined experimentally the quasi-static uniaxial compressive behaviors of a single EPS foam particle and an assembly of many enclosed EPS particles at different loading rates. As representative light-weight closed-cell foam,the mechanical behavior of EPS particle is strongly influenced by the gases enclosed in the cell. The contribution of the gas inside the foam cells is analyzed. For a single foam particle,the contribution of the internal gas on its compressive behavior can be described using a gas model proposed by Ashby et al. A constitutive relationship,considering both effects of the inter gas and the loading rate,is proposed for the compressive behavior of a single EPS particle. For an assembly of enclosed EPS particles,it is shown that both the internal gas and the inter-particle gas affect the mechanical behavior of the

  6. 太子参土壤固氮菌与解钾菌的分离、筛选及鉴定%On Isolation,Screening and Identification of Nitrogen-Fixing Bacteria and Potassium-Solubilizing Bacteria from Rhizosphere Soil of Radix Pseudostellariae

    Institute of Scientific and Technical Information of China (English)

    任建国; 王俊丽


    应用Ashby培养基和亚历山大硅酸盐细菌培养基从太子参根际土壤中分离固氮菌和解钾菌,并选取固氮菌和解钾菌进行固氮、解钾作用研究,以为太子参生物菌肥的研制提供菌源.结果表明:从太子参根际土壤中获得太子参自生固氮菌34株,解钾菌26株.选取固氮菌和解钾菌各5株,分别测定其固氮效能和解钾能力,其中以自生固氮菌ATS 25的固氮效能最高,达21.51 mg/g ;解钾能力最好的菌株为KTS 24,液体培养7 d后水溶性钾含量为7.42 mg/L .菌株培养特征、菌体形态观察、菌株生理生化反应测试并结合16S rDNA分析鉴定,将菌株ATS 25和KTS 24归属为同一个种,即栗树类芽孢杆菌(Paenibacillus castaneae).这是首次报道该菌株具有固氮、解钾作用的研究文献.%Nitrogen‐fixing and potassium‐solubilizing bacteria have been isolated from the rhizosphere soil of Radix Pseudostellariae with Ashby and Alexandrove medium ,respectively .The selected strains have been studied for their nitrogen‐fixing and potassium‐soluilizing abilities so that those could be applied to the production of biofertilizer .The results show that 34 free‐living nitrogen‐fixing bacteria and 26 potassi‐um‐solubilizing bacteria have been achieved from the rhizosphere soil of Radix Pseudostellariae .5 nitro‐gen‐fixing bacteria and 5 potassium‐solubilizing bacteria have been selected for the measures of nitrogen‐fixing efficiency and potassium solubilizing capacities ,respectively .A free‐living nitrogen‐fixing bacterium named ATS‐2‐5 expressed the best nitrogen‐fixing ability , and its value of nitrogen‐fixing efficiency reached 21 .51 mg・g -1 .Potassium‐solubilizing bacterium KTS‐2‐4 has the strongest potassium solubiliz‐ing capacity ,the concentration of soluble potassium in Alexandrove liquid medium is 7 .42 mg・L -1 .ATS‐2‐5 and KTS‐2‐4 are attributed to a

  7. Growth conditions of endophytic diazotroph isolated from Cynodon dactylon%狗牙根内生固氮菌生长条件

    Institute of Scientific and Technical Information of China (English)

    刘天增; 毛中伟; 张巨明


    从已分离的多个狗牙根(Cynodon dactylon)内生固氮菌株中筛选到两株固氮酶活性较高的菌株7 D和 BM13,为明确固氮菌株对环境因子的适应性,研究了在不同的生长环境条件下菌株的生长量.采用 Ashby无氮培养基,测定了温度、pH、渗透压以及不同氮源和碳源等环境条件对固氮菌生长的影响.结果表明,在10~40℃的温度范围内、pH 值3.92~9.64的酸碱环境和30 g.L-1 NaCl 的高渗透压下,固氮菌7D 和 BM13均能正常生长;菌株能耐受0~10 mmol.L-1的 NH4+和 NO3-,而且能利用蔗糖、甘油、麦芽糖、甘露醇和葡萄糖等多种碳源生长.说明狗牙根内生固氮菌株7 D和BM13对环境因子有很强的抗逆性和适应性,但两菌株之间存在一定差异,可望进一步研发成为优良的固氮微生物肥料生产菌种.%Effects of environmental factors on the growth of endophytic diazotroph strains 7D and BM13 isolated from Cynodon dactylon were investigated in our experiment.In this study,strains 7D and BM13 were exam-ined for their adaptability to the stress of temperature,pH,NaCl,NH4 +,NO3 - and carbon sources by Ashby media.The results showed that the two strains could grow under wide range of temperature of 10~40 ℃ and pH from 3.92~9.64.The strains could also tolerate NaCl concentrations of 30 g.L-1 ,NH4 + and NO3 - con-centrations of 0~10 mmol.L-1 ,respectively.The strains were capable of using various carbon sources.It was suggested that the strains 7D and BM13 had superior tolerance to stress of diverse environment factors,but their tolerance abilities differed partly.Endophytic diazotroph strain is a candidate to be further developed for microbial fertilizer production.

  8. 基于孔洞分布理论的多孔材料板振动分析%Vibration Analysis of Foam Plates Based on Cell Volume Distribution

    Institute of Scientific and Technical Information of China (English)

    马宇立; 陈继伟; 刘咏泉; 苏先樾


    Vibration analysis of irregular-closed-cell foam plates was performed. A cell volume distribution coefficient was introduced to modify the original Gibson-Ashby equations of effective Young' s modulus of foam materials. A Burr distribution was imported to describe the cell volume distribution situation. Three Burr distribution parameters were obtained and related to cell volume range and diversity. Based on plate theory and effective modulus theory, natural frequency of foam plates was calculated with the change of cell volume distribution parameters. The relationship between the frequencies and the cell volumes were derived. The scale factor of average cell size was introduced and proved to be an important factor to the performance of the foam plate. The result was proved by the existing theory of size effect. It was determined that the cell volume distribution had an impact on the natural frequency of the plate structure based on cell volume range, diversity and average size, and the impact would lead to optimization of the synthesis procedure.%主要研究了不规则几何结构多孔材料制备的板材的振动分析.基于Gibson-Ashby等效模量计算,引入了分布因子加以改进原有的理论.对于材料的孔洞分布情况,提出了Burr分布的概率密度拟合,获得了Burr分布的3个自变量参数并用实际的孔洞几何参数进行了比对与描述.基于平板振动理论和等效模量理论,计算出了随着孔洞分布情况变化下的平板固有振动频率,并分析了孔洞尺寸与频率间的关系.之后引入了尺度因子来量化描述平均孔洞尺寸对多孔平板的频率影响.结论证明了改进的等效理论能够有效地体现孔洞的分布对平板力学性能的改变,论述了孔洞尺寸范围,孔洞离散度以及平均孔洞尺寸对多孔方板结构固有频率的影响.这种影响将会对多孔材料结构的优化设计起指导作用.

  9. 药用植物鸦胆子内生细菌分离及其抑菌活性研究%Isolation of endophytic bacteria from medicinal plant Brucea javanica L. Merr. and its antifungal activity

    Institute of Scientific and Technical Information of China (English)

    梁子宁; 赖开平; 朱华; 韦茂春; 陈龙


    [Objective]Endophytic bacteria with antagonistic activity were isolated from medicinal plant Brucea javanica L. Merr. to provide references for developing new biological fungicides. [Method]The endophytic bacteria were isolated by tis-sue homogenization and the strains with antifungal activity were screened by in vitro and in vivo antifungal tests. The strains with stronger inhibitory activity was identified based on morphology, physiological and biochemical characteristics, 16S rDNA sequence analysis and Biolog test. [Result]There were 43, 19, 15 and 8 isolates obtained from root, leaf, stem and fruit of Brucea javanica, respectively. Especially, the strain YGB-11 isolated from root showed good antibiosis characteristics with antibacterial rate over 80.00%to Penicillium digitatum (pers.ex Fr.)Sacc of Citrus green mold and Helminthosporium torulosum (Syd.) Ashby of banana helminthosporium leaf spot. Based on morphological, physiological and biochemical characteristics, 16S rDNA sequence analysis and Biolog test, the strain YGB-11 was identified as Bacillus amyloliquefacien. [Conclusion]With wide antimicrobial spectrum and high antifungal activities, YGB-11 has promising prospects.%【目的】从药用植物鸦胆子中分离对植物病原真菌具有拮抗活性的内生细菌,为新型生物杀菌剂的开发提供依据。【方法】采用组织匀浆法对鸦胆子内生细菌进行分离,通过离体和活体组织抑菌试验筛选活性菌株;根据形态特征、生理生化测定、16S rDNA序列分析和Biolog系统对筛选获得的高活性菌株进行鉴定。【结果】从鸦胆子的根、叶、茎和果实部位分别分离得到43、19、15和8株内生细菌,其中分离自根部的YGB-11菌株对柑桔绿霉病菌、香蕉煤纹病菌等7种植物病原菌的抑菌率均超过80.00%,表现出较好的抗菌特性,结合形态特征、生理生化特征、16S rDNA序列分析和Biolog系统鉴定,确定YGB-11菌株

  10. Inoculación de Cilantro (Coriandrum sativum L. con Rizobacterias en Villa del Rosario, Norte de Santander / Inoculation of Cilantro (Coriandrum sativum L. with Rhizobacterias in Villa del Rosario, Norte de Santander

    Directory of Open Access Journals (Sweden)

    Katherine Carrillo Becerra


    Full Text Available Resumen. Las rizobacterias promotoras de crecimiento vegetalrepresentan una alternativa de biofertilización. En este estudiose evaluó el efecto de su inoculación en plantas de cilantro y lautilización de la práctica de quema de cascarilla de arroz en lapreparación del suelo para el establecimiento del cultivo. Seempleó un diseño experimental en parcelas divididas donde, lasparcelas principales correspondieron a la preparación del suelo conquema de cascarilla de arroz y sin quema con la inoculación previade Trichoderma sp. Las subparcelas eran los tratamientos con lainoculación simple y en co-inoculación de Azospirillum RzH132y Azotobacter RzH120 y los testigos absoluto y químico. Unavez se comprobaron los supuestos en los residuales del modelo,normalidad, homogeneidad de varianzas y aleatoriedad, se realizóel análisis de varianza y pruebas de comparación múltiple porel test de Tukey y un análisis de componentes principales comotécnica de reducción de dimensiones. Los resultados mostraronun efecto positivo en el crecimiento de las plantas inoculadas conlas rizobacterias en las dos parcelas con quema y sin quema decascarilla de arroz; sin embargo, en la variable rendimiento nose obtuvieron diferencias significativas (P≤0,05. Así mismo, seencontró que la población de bacterias rizosféricas en los mediosde cultivo NFb semisólido, Ashby y King B, se vio favorecida por lano quema de cascarilla de arroz en el suelo. Es importante resaltarque los resultados se obtuvieron con la disminución al 30% de lafertilización química, con lo cual se puede reducir el uso de estosproductos químicos. /  Abstract. Plant growth promoting rhizobacteria (PGPR representan alternative biofertilization form. In this study, was evaluatedPGPR inoculation in cilantro plants. Likewise, was evaluatedthe practice of burning rice husk in soil preparation for cropestablishment. An experimental design was used in a split plotwhere the main plots were

  11. Theoretical and experimental researches of size effect in micro-indentation test

    Institute of Scientific and Technical Information of China (English)

    WEI; Yueguang


    [1]Nix, W. D., Gao, H., Indentation size effects in crystalline materials: a law for strain gradient plasticity, J. Mech. Phys. Solids, 998, 46(3): 4.[2]McElhaney, K. W., Vlassak, J. J., Nix, W. D., Determination of indenter tip geometry and indentation contact area for depth-sensing indentation experiments, J. Mater. Res., 998, 3(5): 300.[3]Begley, M., Hutchinson, J. W., The mechanics of size-dependent indentation, J. Mech. Phys. Solids, 998, 46: 029.[4]Shu, J. Y., Fleck, N. A., The prediction of a size effect in micro-indentation, Int. J. Solids Structures, 998, 35(3): 363.[5]Poole, W. J., Ashby, M. F., Fleck, N. A., Micro-hardness tests on annealed and work-hardened copper polycrystals, Scripta Metall Mater, 996, 34: 559.[6]Atkinson, M., Further analysis of the size effective in indentation hardness tests of some metals, J. Mater. Res., 995, 0: 2908.[7]Ma, Q., Clarke, D. R., Size dependent hardness of silver single crystals, J. Mater. Res., 995, 0: 853.[8]Stelmashenko, N. A., Walls, M. G., Brown, L. M. et al., Microindentation on W and Mo priented single crystals: an STM study, Acta Metall Mater, 993, 4: 2855.[9]Cheng, Y. T., Cheng, C. M., Scaling relationships in conical indentation of elastic-perfectly plastic solids, Int. J. Solids Structures, 999, 36: 23.[10]Fleck, N. A., Hutchinson, J. W., Strain gradient plasticity, in Advances in Applied Mechanics (eds. Hutchinson, J. W., Wu, T. Y.), 997, 33: 295.[11]Gao, H., Huang, Y., Nix, W. D. et al., Mechanism-based strain gradient plasticity —Ⅰ, Theory. J Mech Phys Solids, 999, 47: 239.[12]Aifantis, E. C., On the microstructural origin of certain inelastic models, Trans. ASME J. Eng. Mater. Tech., 984, 06: 326.[13]Wei, Y., Hutchinson, J. W., Steady-state crack growth and work of fracture for solids characterized by strain gradient plasticity, J. Mech. Phys. Solids, 997, 45(8): 253.[14]Timoshenko, S. P., Goodier, J. N., Theory of Elasticity, 3rd ed., New

  12. Microbiota of coal pit waste heaps of Chervonograd Mining Region after coal ash application

    Directory of Open Access Journals (Sweden)

    S. V. Kuzmishyna


    Full Text Available The aim of this work was to determine the impact of addition of coal ash from Dobrotvir TPP to waste heaps gangue (Chervonograd Mining Region on the number of different groups of microorganisms. 20 samples from three waste heaps, from the black and red gangue, under the mosses and from bare substrate and also from terrace, top and base of each waste heap, were selected. Waste heaps gangues with coal ash from Dobrotir TPP were mixed in vitro and left for 10 days. We used proportion of coal ash to gangue as 1 to 5. Microorganisms were grown in Petri dishes containing 20–30 ml agar medium and in 22 ml tubes at temperature of 28 °C. Microscopic fungi were revealed on Mash-agar; oligonitrophilic bacteria – on Ashby medium; actinomycetes – on Chapek’s medium; cellulose decomposing aerobic bacteria – on Hetchenson medium; colorless sulfur oxidizing bacteria: neutrophilic – on Beyerinck medium, acidophilic – on Silverman and Lundgren 9К medium. The acidity value of waste heaps gangue samples was determined by рН meter рН-150М. We observed that samples collected under the mosses had lower acidity compared to samples from the bare substrate. We also revealed lower acidity of the overburn red gangue than the acidity of freshly deposited black gangue. To sum up, application of coal ash resulted in lowering of acidity value among all samples under study. Coal ash addition led to increase in number of microscopic fungi cells compared to the appropriate control samples. The highest quantity of microscopic fungi (16.2 ± 0.79 х 105 CFU/g of gangue was revealed in sample from red rock of the main waste heap of Central Enrichment Plant (CEP. At the same time, we observed the highest cell number in the control sample under the mosses of “Nadija” coal pit waste heap, (6.1 ± 0.3 х 105 CFU/g of gangue. After coal ash addition, most samples featured 2–3 times higher quantities of colorless sulfur-oxidizing neutrophilic bacteria cells. The

  13. Screening of Nitrogen-fixing Bacteria in Rhizosphere of Cunninghaimia Lanceolata and Investigation on Their Properties of Phosphate-solubilizing and IAA-producing%杉木根际固氮菌筛选及其溶磷性与分泌IAA特性研究

    Institute of Scientific and Technical Information of China (English)

    周德明; 李蓉


    Chinese fir ( Cunninghaimia Lanceolata) is a main tree species of planted fast-growing forest in China. The problem on rapid reduction of soil fertility resulted from nutrient consumption of Chinese fir plantation still remains to be solved since the studies on screening and application of rhizosphere bacteria of Chinese fir with growth-promoting effect are rarely reported. In our study, 16 strains of nitrogen-fixing bacteria are isolated from rhizosphere soil of Chinese fir by measurement of nitrogenase activities using acetylene reduction assay after culturing in Ashby medium. Their abilities of dissolving inorganic and organic phosphorus are evaluated by dissolving phosphate zone on Menkina media and molybdenum blue spectrophotometry. IAA-producing abilities of the strains are measurated by the Salkowski colorimetry. The results indicate that 5 strains show high potential of nitrogen fixing with nitrogenase activity of over 150 nmol · mL-1 · h-1. NGJ-4 has the highest nitrogenase activity (264.7 nmol · mL-1 · h-1) and NCX-5 takes the second place (237.4 nmol · mL-1 · h-1'). There are 8 strains with abilitiy of dissolving inorganic phosphorus. The available phosphorus increments of NGJ-8, NGJ-4 and NGX-3 are 182.7, 158.4 and 133.9 mg · L-1, respectively, which can't dissolve organic phosphorus. There are 5 strains with low dissolving organic phosphorus abilitiy. The highest available phosphorus increments derived from organic phosphorus is only 46.1 mg · L-1 of NGX-5. Most of the strains can secrete IAA. The first 5 strains have a high IAA concentration of more than 20 mg · L-1 in supernatant of bacteria solution. The IAA concentration levels of NGX-5, NGJ-3, NGJ-4 and NCX-3 are 35.8, 32.1, 27.8 and 27. 7 mg · L-1, respectively. Consequently, NGJ-4, NGX-5 and NGJ-8 integrated prominent nitrogen-fixing, phosphorus-dissolving and IAA-producing can be utilized in developing multiple-effective microbial fertilizer.%我国特有速生用材林主要造林

  14. Foreword: In situ gas surface interactions: approaching realistic conditions (United States)

    Lundgren, Edvin; Over, Herbert


    Weilach C 2008 Spectroscopic studies of surface-gas interactions and catalyst restructuring at ambient pressure: mind the gap! J. Phys.: Condens. Matter 20 184019 [14] Evans M and Tromp M 2008 Interaction of small gas phase molecules with alumina supportedrhodium nanoparticles: an in situ spectroscopic study J. Phys.: Condens. Matter 20 184020 [15] Stampfl C, Soon A, Piccinin S, Shi H and Zhang H 2008 Bridging the temperature and pressure gaps: close-packed transition metal surfaces in an oxygen environment J. Phys.: Condens. Matter 21 184021 [16] Li W-X 2008 Oxidation of platinum surfaces and reaction with carbon monoxide J. Phys.: Condens. Matter 20 184022 [17] Seriani N and Mittendorfer F 2008 Platinum-group and noble metals under oxidizing conditions J. Phys.: Condens. Matter 20 184023 [18] Ketteler G, Ashby P, Mun B S, Ratera I, Bluhm H, Kasemo B and Salmeron M 2008 In situ photoelectron spectroscopy study of water absorption on model biomaterial surfaces J. Phys.: Condens. Matter 20 184024 [19] Yamamoto S, Bluhm H, Andersson K, Ketteler G, Ogasawara H, Salmeron M and Nilsson A 2008 In situ x-ray photoelectron spectroscopy studies of water on metals and oxides at ambient conditions J. Phys.: Condens. Matter 20 184025

  15. EDITORIAL: Special issue on applied neurodynamics: from neural dynamics to neural engineering Special issue on applied neurodynamics: from neural dynamics to neural engineering (United States)

    Chiel, Hillel J.; Thomas, Peter J.


    Tracing technologies back in time to their scientific and mathematical origins reveals surprising connections between the pure pursuit of knowledge and the opportunities afforded by that pursuit for new and unexpected applications. For example, Einstein's desire to eliminate the disparity between electricity and magnetism in Maxwell's equations impelled him to develop the special theory of relativity (Einstein 1922)Einstein 1922 p 41 'The advance in method arises from the fact that the electric and magnetic fields lose their separate existences through the relativity of motion. A field which appears to be purely an electric field, judged from one system, has also magnetic field components when judged from another inertial system.'. His conviction that there should be no privileged inertial frame of reference Einstein 1922 p 58 'The possibility of explaining the numerical equality of inertia and gravitation by the unity of their nature gives to the general theory of relativity, according to my conviction, such a superiority over the conceptions of classical mechanics, that all the difficulties encountered must be considered as small in comparison with this progress.' further impelled him to utilize the non-Euclidean geometry originally developed by Riemann and others as a purely hypothetical alternative to classical geometry as the foundation for the general theory of relativity. Nowadays, anyone who depends on a global positioning system—which now includes many people who own smart phones—uses a system that would not work effectively without incorporating corrections from both special and general relativity (Ashby 2003). As another example, G H Hardy famously proclaimed his conviction that his work on number theory, which he pursued for the sheer love of exploring the beauty of mathematical structures, was unlikely to find any practical applications (Hardy 1940)Hardy 1940 pp 135-6 'The general conclusion, surely, stands out plainly enough. If useful knowledge