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Sample records for albilineans ashby dowson

  1. Gluconacetobacter diazotrophicus Elicits a Sugarcane Defense Response Against a Pathogenic Bacteria Xanthomonas albilineans

    Science.gov (United States)

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

    2006-01-01

    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

  2. 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

    2012-11-01

    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

  3. An experimental evaluation of the Hamrock and Dowson minimum film thickness equation for fully flooded EHD point contacts

    Science.gov (United States)

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

    1980-08-01

    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.

  4. Modeling Valuations from Experience: A Comment on Ashby and Rakow (2014)

    Science.gov (United States)

    Wulff, Dirk U.; Pachur, Thorsten

    2016-01-01

    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…

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

    Science.gov (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

    2006-01-01

    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.

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

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    Dragana Radunović

    2012-01-01

    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.

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

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    Liliana Serna-Cock

    2013-09-01

    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.

  8. 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.

    Science.gov (United States)

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

    2011-02-01

    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.

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

    International Nuclear Information System (INIS)

    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)

  10. 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

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    Karina Maia Dabbas

    2006-09-01

    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

  11. Multiple hydrolases in bean leaves (Phaseolus vulgaris L.) and the effect of the halo blight disease caused by Pseudomonas phaseolicola (Burkh.) Dowson.

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    Rudolph, K; Stahmann, M A

    1966-03-01

    Multiple forms of hydrolytic enzymes were demonstrated in extracts of healthy bean leaves (Phascolus vulgaris L.) and bean leaves infected with the halo blight organism [Pseudomonas phaseolicola (Burkh.) Dowson] by polyacrylamide disc electrophoresis. Bean leaves contained up to 4 acid phosphatase bands, 9 esterase bands active towards alpha-naphthyl acetate, and 7 esterase bands towards alpha-naphthyl butyrate. Only low or no activity was found for alkaline phosphatase, lipase, and aminopeptidase. Two artifacts are described which were observed with the lead phosphate method for acid phosphatase and the Tween method for demonstration of lipase. After infection with the halo blight organism the major acid phosphatase of the host increased during early and decreased at later infection stages. An acid phosphatase of bacterial origin with a more neutral pH optimum could be demonstrated in infected leaves. It is suggested that the bacterial acid phosphatase plays a role in uptake of metabolites by the pathogen. Several esterase bands decreased after infection. One host band with activity towards alpha-naphthyl butyrate increased. Also the pathogen showed an esterase band with high activity towards alpha-naphthyl butyrate. PMID:5906374

  12. 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

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    Anderson Silva

    2011-03-01

    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.

  13. 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

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    Anderson Gonçalves Da Silva

    2011-03-01

    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.

  14. 防治烟草青枯病的药剂筛选%Chemical screening for controlling Pseudomonas solanacearum (E. F. Smith) Dowson

    Institute of Scientific and Technical Information of China (English)

    贾春燕; 郑洪波; 张茹萍; 贾玉; 郑翠梅; 张广民; 陈秀斋; 温亮

    2010-01-01

    根据各药剂的药效范围和理化特性选择了11种单剂及其部分复配剂进行了室内药剂筛选试验.结果表明:72%农用硫酸链霉素及氧氯化铜∶消菌灵=1∶1对烟草青枯病的抑菌效果较好,且药效稳定.

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

    OpenAIRE

    Wahyuni, Siti Hardianti

    2016-01-01

    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...

  16. 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

    2011-03-01

    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.

  17. 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.

    Science.gov (United States)

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

    2010-04-01

    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.

  18. 7 CFR 319.19 - Notice of quarantine.

    Science.gov (United States)

    2010-01-01

    ... SERVICE, DEPARTMENT OF AGRICULTURE FOREIGN QUARANTINE NOTICES Citrus Canker and Other Citrus Diseases... citrus canker disease (Xanthomonas citri (Hasse) Dowson) and other citrus diseases, the importation...

  19. Complex of f-elements with heteropolyanions

    International Nuclear Information System (INIS)

    Literature data on structure and properties of lanthanide and actinide complexes with non-saturated heteropolyanions having Keggin's or Dowson's structure are collected and generalized. Stability, thermodynamic and chemical properties of complexes in solutions, their luminescence in solutions and in crystalline state are considered. The methods of separation of f-elements based on their complexing with heteropolyanions are discussed

  20. The Phytotoxin Albicidin is a Novel Inhibitor of DNA Gyrase▿

    OpenAIRE

    Saeed M. Hashimi; Wall, Melisa K.; Smith, Andrew B; Maxwell, Anthony; Birch, Robert G.

    2006-01-01

    Xanthomonas albilineans produces a family of polyketide-peptide compounds called albicidins which are highly potent antibiotics and phytotoxins as a result of their inhibition of prokaryotic DNA replication. Here we show that albicidin is a potent inhibitor of the supercoiling activity of bacterial and plant DNA gyrases, with 50% inhibitory concentrations (40 to 50 nM) less than those of most coumarins and quinolones. Albicidin blocks the religation of the cleaved DNA intermediate during the ...

  1. Genomes-based phylogeny of the genus Xanthomonas

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    Rodriguez-R Luis M

    2012-03-01

    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.

  2. Light-weight materials selection for High-Speed Naval Craft

    OpenAIRE

    Torrez, Joseph B.

    2007-01-01

    CIVINS A decision analysis study was conducted on the process of materials selection for high-speed naval craft using the Modified Digital Logic (MDL) method. The purpose is to show how this method along with Ashby's material selection process can be integrated to provide a comprehensive tool designed specifically for light-weight material optimization. Using Ashby's Material Selection Charts and the MDL method, a step by step material selection process is outlined. Furthermore, a comparis...

  3. Fantasy as a mode in British and Irish literary decadence, 1885–1925

    OpenAIRE

    Mercurio, Jeremiah Romano

    2011-01-01

    This Ph.D. thesis investigates the use of fantasy by British and Irish 'Decadent' authors and illustrators, including Oscar Wilde, Max Beerbohm, Aubrey Beardsley, 'Vernon Lee' (Violet Paget), Ernest Dowson, and Charles Ricketts. Furthermore, this study demonstrates why fantasy was an apposite form for literary Decadence, which is defined in this thesis as a supra-generic mode characterized by its anti-mimetic impulse, its view of language as autonomous and artificial, its frequent use of...

  4. The Phytotoxin Albicidin is a Novel Inhibitor of DNA Gyrase▿

    Science.gov (United States)

    Hashimi, Saeed M.; Wall, Melisa K.; Smith, Andrew B.; Maxwell, Anthony; Birch, Robert G.

    2007-01-01

    Xanthomonas albilineans produces a family of polyketide-peptide compounds called albicidins which are highly potent antibiotics and phytotoxins as a result of their inhibition of prokaryotic DNA replication. Here we show that albicidin is a potent inhibitor of the supercoiling activity of bacterial and plant DNA gyrases, with 50% inhibitory concentrations (40 to 50 nM) less than those of most coumarins and quinolones. Albicidin blocks the religation of the cleaved DNA intermediate during the gyrase catalytic sequence and also inhibits the relaxation of supercoiled DNA by gyrase and topoisomerase IV. Unlike the coumarins, albicidin does not inhibit the ATPase activity of gyrase. In contrast to the quinolones, the albicidin concentration required to stabilize the gyrase cleavage complex increases 100-fold in the absence of ATP. The slow peptide poisons microcin B17 and CcdB also access ATP-dependent conformations of gyrase to block religation, but in contrast to albicidin, they do not inhibit supercoiling under routine assay conditions. Some mutations in gyrA, known to confer high-level resistance to quinolones or CcdB, confer low-level resistance or hypersensitivity to albicidin in Escherichia coli. Within the albicidin biosynthesis region in X. albilineans is a gene encoding a pentapeptide repeat protein designated AlbG that binds to E. coli DNA gyrase and that confers a sixfold increase in the level of resistance to albicidin in vitro and in vivo. These results demonstrate that DNA gyrase is the molecular target of albicidin and that X. albilineans encodes a gyrase-interacting protein for self-protection. The novel features of the gyrase-albicidin interaction indicate the potential for the development of new antibacterial drugs. PMID:17074789

  5. Nunca mucho costó poco [Grabación sonora

    OpenAIRE

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

    2005-01-01

    Duración: 1:25. 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 ; Helen Ashby, soprano ; Kate Ashby, soprano ; Hervé Lamy, tenor. Director: Àngel Recasens. Fuente: Libro de Tonos Humanos (s.XVII), Biblioteca Nacional. Cancionero Poético-Musical Hispánico de Lisboa (s.XVII), Bibliotca de Ajuda. Productor ejecutivo, asesor musicológico y ...

  6. Pentapeptide-repeat proteins that act as topoisomerase poison resistance factors have a common dimer interface

    International Nuclear Information System (INIS)

    The pentapeptide repeat protein AlbG, provides self-resistance to the nonribosomally encoded hybrid polyketide-peptide termed albicidin. Analysis of the AlbG three-dimensional structure and the sequences of other pentapeptide repeat proteins that confer resistance to topiosomerase poisons suggests they have a similar dimer interface which may be critical to their interaction with topoisomerases. The protein AlbG is a self-resistance factor against albicidin, a nonribosomally encoded hybrid polyketide-peptide with antibiotic and phytotoxic properties produced by Xanthomonas albilineans. Primary-sequence analysis indicates that AlbG is a member of the pentapeptide-repeat family of proteins (PRP). The structure of AlbG from X. albilineans was determined at 2.0 Å resolution by SAD phasing using data collected from a single trimethyllead acetate derivative on a home source. AlbG folds into a right-handed quadrilateral β-helix composed of approximately eight semi-regular coils. The regularity of the β-helix is blemished by a large loop/deviation in the β-helix between coils 4 and 5. The C-terminus of the β-helix is capped by a dimerization module, yielding a dimer with a 110 Å semi-collinear β-helical axis. This method of dimer formation appears to be common to all PRP proteins that confer resistance to topoisomerase poisons and contrasts with most PRP proteins, which are typically monomeric

  7. Perfectionism, Depression, Loneliness, and Life Satisfaction: A Study of High School Students in Hong Kong

    Science.gov (United States)

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

    2009-01-01

    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…

  8. Book review: writing history in international criminal trials

    OpenAIRE

    O'Leary, Tara

    2012-01-01

    In this engaging and accessible book, Richard Ashby Wilson addresses key questions related to the legal relevance of history in international criminal trials. Should history play a role in trials, what form should it take, and why does it matter? What can history explain about criminal accountability, crimes under international law, and conflict? Reviewed by Tara O’Leary.

  9. Empathy in History. Understanding a Past Institution (Ordeal) in Children and Young Adults when Description and Rationale Are Provided

    Science.gov (United States)

    Berti, Anna Emilia; Baldin, Isabella; Toneatti, Laura

    2009-01-01

    A total of 150 students, from 8 to 25 years, were interviewed about ordeal in the Middle Ages, after reading a shorter and simplified version of a text used in previous research on this topic (e.g., [Lee, P. J., & Ashby, R. (2001). Empathy, perspective taking, and rational understanding. In O. L. Davis, Jr., S. Foster, & E. Yaeger (Eds.),…

  10. Individual and Family Perfectionism and Its Relationship to Depression, Anxiety, and Self-Esteem among Latino College Students

    Science.gov (United States)

    Ortega, Norma E.

    2010-01-01

    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…

  11. STS-93: Crew Watch the Installation of Chandra's Solar Panel in the VPF

    Science.gov (United States)

    1999-01-01

    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, watching the installation of Chandra's Solar Panel in the Vertical Processing Facility (VPF) at Kennedy Space Center. Crewmembers ask the engineers questions about different components in order to familiarize themselves.

  12. 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

    2016-01-01

    研究了润滑油密度与黏度的关系,并提出了一个由密度求黏度的新黏压关系式.以Dowson-Higginson密度公式为媒介,新公式只改变一个常数可退化为Barus黏压关系,而改变两个常数可退化为Doolittle自由体积黏压关系.用Dowson-Higginson密压关系消去密度,新公式具有与Roelands黏压关系相同的结构,但对应常数各不相同.以squalane油为例,给出了由实验数据确定新公式中两个待定常数的简单方法,而如此确定下来的新公式可以与全部实验数据吻合良好.应用新公式计算黏度并以squalane油品为润滑剂,可顺利求得等温椭圆接触弹性流体动力润滑的数值解,说明新公式具有良好的适应性.

  13. Special Operations Forces: A Global Immune System?

    CERN Document Server

    Norman, Joseph

    2016-01-01

    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...

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

    OpenAIRE

    Daniel Borda-Molina; Juan Manuel Pardo-García; María Mercedes Martínez-Salgado; José Salvador Montaña-Lara

    2009-01-01

    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 fast...

  15. Requisite Variety, Autopoiesis, and Self-organization

    OpenAIRE

    Gershenson, Carlos

    2014-01-01

    Ashby's law of requisite variety states that a controller must have at least as much variety (complexity) as the controlled. Maturana and Varela proposed autopoiesis (self-production) to define living systems. Living systems also require to fulfill the law of requisite variety. A measure of autopoiesis has been proposed as the ratio between the complexity of a system and the complexity of its environment. Self-organization can be used as a concept to guide the design of systems towards higher...

  16. SOME PROPERTIES OF MELANIN PRODUCED BY AZOTOBACTER CHROOCOCCUM AND ITS POSSIBLE APPLICATION IN BIOTECHNOLOGY

    OpenAIRE

    Gospodaryov, D.; Lushchak, V.

    2011-01-01

    The strain of bacteria Azotobacter chroococcum, producing and excreting melanin, was isolated. Melanin excretion was observed only on Ashby medium with benzoic acid, but not on the medium with mannitol as carbon source. Some properties of bacterial melanin (absorption spectrum, reduction of permanganates to manganates, rate of bleaching by hydrogen peroxide, coprecipitation with calcium ions) and conditions of its production (dependence on copper ion concentration) were described. A scheme of...

  17. STS-93: Columbia, Flight Crew Training with M-113 for Chandra

    Science.gov (United States)

    1999-01-01

    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.

  18. FCJ-118 Faulty Theory

    OpenAIRE

    Matthew Fuller

    2011-01-01

    Faulty Theory proposes a few means by which theory may be operative in media ecology, providing capacities for inducing and experimenting with a range of media dynamics. The article develops accounts of the work of Alfred Jarry and Charles Fort, alongside a discussion of a certain current of thought experiment carried out in cybernetics through the development of robots and other devices by Gordon Pask, Grey Walter and W. Ross Ashby. The article proposes possible resonances between theoretica...

  19. Perceived association between diagnostic and non-diagnostic cues of women's sexual interest: General Recognition Theory predictors of risk for sexual coercion

    OpenAIRE

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

    2010-01-01

    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 c...

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

    DEFF Research Database (Denmark)

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

    2014-01-01

    values of six gear lubricants, two of them reference mineral oils and the other four developed biodegradable oils based in high oleic sunflower oil or in synthetic esters. It was found that all of the lubricants have both similar compressibilities and similar expansivities. Dowson and Higginson, Zhu......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...... the knowledge of their thermophysical properties such as their viscosity or density, among others. Regarding this issue, in this work, we have carried out density measurements between 278.15 and 398.15 K and pressures up to 120 MPa and calculated the isothermal compressibility and isobaric thermal expansivity...

  1. Contact and Bending Durability Calculation for Spiral-Bevel Gears

    Science.gov (United States)

    Vijayakar, Sandeep

    2016-01-01

    The objective of this project is to extend the capabilities of the gear contact analysis solver Calyx, and associated packages Transmission3D, HypoidFaceMilled, HypoidFaceHobbed. A calculation process for the surface durability was implemented using the Dowson-Higginson correlation for fluid film thickness. Comparisons to failure data from NASA's Spiral Bevel Gear Fatigue rig were carried out. A bending fatigue calculation has been implemented that allows the use of the stress-life calculation at each individual fillet point. The gears in the NASA test rig did not exhibit any bending fatigue failure, so the bending fatigue calculations are presented in this report by using significantly lowered strength numbers.

  2. The Teacher’s Role of Listening Comprehension

    Institute of Scientific and Technical Information of China (English)

    WANG Yun

    2015-01-01

    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.

  3. Numerical Simulation of Piston Ring Lubrication

    DEFF Research Database (Denmark)

    Felter, Christian Lotz

    2006-01-01

    This paper describes a numerical method that can be used to model the lubrication of piston rings. Classical lubrication theory is based on the Reynolds equation which is ap- plicable to confined geometries and open geometries where the flooding conditions are known. Lubrication of piston rings......, however, fall outside this category of problems since the piston rings might suffer from starved running conditions. This means that the com- putational domain where Reynold equation is applicable (including a cavitation criteria) is unknown. In order to overcome this problem the computational domain...... variables u, v, rho for the velocity components and density, respectively. Time integration is performed by a third order Runge-Kutta method. The set of equations is closed by the Dowson- Higginson equation for the relation between density and pressure. Boundary conditions are the non-slip condition...

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

    International Nuclear Information System (INIS)

    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. Phylogenetic analysis of Xanthomonas based on partial rpoB gene sequences and species differentiation by PCR-RFLP.

    Science.gov (United States)

    Ferreira-Tonin, Mariana; Rodrigues-Neto, Júlio; Harakava, Ricardo; Destéfano, Suzete Aparecida Lanza

    2012-06-01

    The rpoB gene was evaluated as an alternative molecular marker for the differentiation of Xanthomonas species and in order to understand better the phylogenetic relationships within the genus. PCR-RFLP experiments using HaeIII allowed differentiation of Xanthomonas species, particularly those that affect the same plant host such as Xanthomonas albilineans and X. sacchari, pathogenic to sugar cane, Xanthomonas cucurbitae and X. melonis, which cause disease in melon, and Xanthomonas gardneri, X. vesicatoria and X. euvesicatoria/X. perforans, pathogenic to tomato. Phylogenetic relationships within the genus Xanthomonas were also examined by comparing partial rpoB gene sequences (612 nt) and the Xanthomonas species were separated into two main groups. Group I, well supported by bootstrap values of 99 %, comprised X. euvesicatoria, X. perforans, X. alfalfae, X. citri, X. dyei, X. axonopodis, X. oryzae, X. hortorum, X. bromi, X. vasicola, X. cynarae, X. gardneri, X. campestris, X. fragariae, X. arboricola, X. cassavae, X. cucurbitae, X. pisi, X. vesicatoria, X. codiaei and X. melonis. Group II, again well supported by bootstrap values of 99 %, comprised X. albilineans, X. sacchari, X. theicola, X. translucens and X. hyacinthi. The rpoB gene sequence similarity observed among the species in this study ranged from 87.8 to 99.7 %. The results of PCR-RFLP of the rpoB gene indicated that this technique can be used for diagnosis and identification of most Xanthomonas strains, including closely related species within the genus. However, species that showed identical profiles could be differentiated clearly only by sequence analysis. The results obtained in our phylogenetic analysis suggested that the rpoB gene can be used as an alternative molecular marker for genetic relatedness in the genus Xanthomonas. The results of PCR-RFLP of the rpoB gene indicate that this technique can be used for diagnosis and identification of closely related species within the genus, representing

  6. Cybernetic brain sketches of another future

    CERN Document Server

    Pickering, Andrew

    2014-01-01

    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

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

    CERN Document Server

    Pullin, J

    1997-01-01

    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

  8. Quien tanto veros desea [Grabación sonora

    OpenAIRE

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

    2005-01-01

    Duración: 2:59. 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 ; Helen Ashby, soprano ; Sytse Buwalda, contratenor ; Lieven Termont, barítono. Director: Àngel Recasens. Fuente: Libro de Tonos Humanos (s.XVII). Biblioteca Nacional. Productor ejecutivo, asesor musicológico y editor: Albert Recasens. Textos en español, inglés, francés y a...

  9. Sancho Panza es aqueste [Grabación sonora

    OpenAIRE

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

    2005-01-01

    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....

  10. Suelen las fuerzas de amor [Grabación sonora

    OpenAIRE

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

    2005-01-01

    Duración: 2:24. 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 ; Helen Ashby, soprano ; Sytse Buwalda, contratenor ; Hervé Lamy, tenor. Director: Àngel Recasens. Fuente: Cancionero Poético-Musical Hispánico de Lisboa (s.XVII). Biblioteca de Ajuda. Productor ejecutivo, asesor musicológico y editor: Albert Recasens. Textos en español, in...

  11. Yace aquí el hidalgo fuerte [Grabación sonora

    OpenAIRE

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

    2005-01-01

    Duración: 3:35. 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 ; Helen Ashby, soprano ; Sytse Buwalda, contratenor ; Hervé Lamy, tenor ; Lieven Termont, barítono. Director: Àngel Recasens. Fuente: M. 755/4. Biblioteca de Catalunya. Productor ejecutivo, asesor musicológico y editor: Albert Recasens. Textos en español, inglés, francés y ...

  12. THREE-DIMENSIONAL ANALYSIS OF SCALE DEPENDENCE OF SUB-MICRON POLYCRYSTALS DUE TO CONFIGURATION ENTROPY

    Institute of Scientific and Technical Information of China (English)

    杨强; 杨卫

    2001-01-01

    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. 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

    2006-01-01

    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.

  14. Precipitates in HSLA steels. Ausscheidungen in mikrolegierten schweissbaren Feinkornbaustaehlen

    Energy Technology Data Exchange (ETDEWEB)

    Kneissl, A. (Montanuniversitaet Leoben (Austria). Inst. fuer Metallkunde und Werkstoffpruefung)

    1990-09-01

    Particles in a microalloyed steel (microalloying additions: V, Nb, Ti) are characterized with respect to size, shape and chemistry by using STEM-EDX for precipitates which are larger than 10 nm and by an atom-probe field ion microscope for smaller ones. A comparison is given between particles existing in the as-cast material and in the TMT samples explaining how the different classes of precipitates can influence the structure and thereby the mechanical properties. The precipitation hardening is estimated using a model of Ashby-Orowan and the yield stress is calculated from the amounts of the different strengthening mechanisms fitting well to the measured data. (orig.).

  15. Open-cellular copper structures fabricated by additive manufacturing using electron beam melting

    International Nuclear Information System (INIS)

    Highlights: → Relative stiffness versus relative density measurements for reticulated mesh and stochastic open cellular copper were shown to follow the Gibson-Ashby foam model. → Microstructures for the mesh struts and foam ligaments illustrated a propensity of copper oxide precipitates which provided structural hardness and strength. → These components, fabricated by electron beam melting, exhibit interesting prospects for specialized, complex heat-transfer devices. - Abstract: Cu reticulated mesh and stochastic open cellular foams were fabricated by additive manufacturing using electron beam melting. Fabricated densities ranged from 0.73 g/cm3 to 6.67 g/cm3. The precursor Cu powder contained Cu2O precipitates and the fabricated components contained arrays of Cu2O precipitates and interconnected dislocation microstructures having average spacings of ∼2 μm, which provide hardness values ∼75% above commercial Cu products. Plots of stiffness (Young's modulus) versus density and relative stiffness versus relative density were in very close agreement with the Gibson-Ashby model for open cellular foams. These open cellular structure components exhibit considerable potential for novel, complex, multi-functional electrical and thermal management systems, especially complex, monolithic heat exchange devices.

  16. Nanocarbonitride precipitation contribution to the yield stress of a V-Nb microalloyed steel.

    Science.gov (United States)

    Sobral, M D C; Mei, P R; Kestenbach, H J

    2010-02-01

    Nanocarbonitride precipitation during thermomechanical processing is well known as one of the important mechanisms to increase mechanical properties of hot rolled microalloyed steels. Some studies of industrial hot rolled strips have quantified the contribution of the different ways of precipitation: in austenite, at the interface austenite/ferrite, or in supersaturated ferrite during final cooling. Thin slabs of microalloyed steels (0.07-0.08% V and 0.02-0.04% Nb) were thermomecanically processed on a laboratory-scale rolling mill. The different modes of nanocarbonitride precipitation were investigated by transmission electron microscopy. It was observed interphase precipitation with average diameter of nanocarbonitride of 4.4 nm and potential contribution to strengthening of 90 MPa, according to the Orowan-Ashby model. From the Orowan-Ashby model of precipitation strengthening, strength contributions of about 50 MPa were found for nanocarbonitride particles formed in austenite. The inclusion of a holding extra period of 15 minutes just below the Finishing Rolling Initial Temperature has confirmed an important contribution to the yield stress given by the nanocarbonitride particles formed in austenite. PMID:20352782

  17. STS-112/Atlantis/ISS 9A Pre-Launch - Launch On-Orbit - Landing - Crew Egress

    Science.gov (United States)

    2002-01-01

    The video starts with an introduction of the crew of Space Shuttle Atlantis on STS-112 at their customary pre-flight meal. The crew consists of Commander Jeffrey Ashby, Pilot Pam Melroy, and Mission Specialists David Wolf, Sandra Magnus, Piers Sellers, and Fyodor Yurchikhin. The crew is then shown during suit-up, while exiting the Operations and Checkout Building to board the Astrovan, and during ingress and seating. Launch views include: Beach Tracker, VAB, PAD-B, Tower-1, DLTR-3, Grandstand, Cocoa Beach DOAMS, Playalinda DOAMS, UCS-23, OTV-170, OTV-171, and External Tank Camera. On-orbit footage includes the Atlantis orbiter docking with the ISS (International Space Station). The video shows clips of extravehicluar activities (EVAs), and some of the tasks performed during the mission. Footage included shows the installation of the S1 Truss onto the ISS with the Space Station Remote Manipulator System (Canadarm 2), Canadarm 2 carrying the Ammonia Tank Assembly prior to connection, the checkout of the Thermal Radiator Rotary Joint, the soft docking of an S-Band antenna, and the deployment of the S1 Radiator. An onboard repair of the ISS humidity separator is also shown. Landing views include: VAB, Tower 1, Mid-Field, Runway South End, Runway North End, Tower-2, Cocoa Beach DOAMS, and PPOV. Kennedy Space Center managers greet the crew upon arrival, and Commander Ashby gives a brief speech while standing with his crew members.

  18. 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: wangk2@rpi.edu; 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)

    2005-07-15

    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.

  19. Influence of using nanoobjects as filler on functionality-based energy use of nanocomposites

    International Nuclear Information System (INIS)

    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. Some basic properties of environmentally adapted oils

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-11-01

    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.

  1. 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

    2006-12-01

    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

  2. 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

  3. 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

    2005-12-01

    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

  4. 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

    2006-12-01

    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

  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. 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

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

    DEFF Research Database (Denmark)

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

    2011-01-01

    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......-Tenant rules) and predictions were negative for several assays: Ames test, chromosomal aberration in Chinese hamster lung cells, mouse lymphoma TK cell mutation and unscheduled DNA synthesis in rat hepatocytes. The in vitro Ames test showed that the plasticiser did not induce gene mutations in bacteria....... Presently, an in vivo comet assay to investigate the ability of the plasticiser to induce DNA strand breaks after oral exposure in the liver and kidney of rats is under conduction....

  8. Preliminary investigation of aluminium foam as an energy absorber for nuclear transportation cask

    Energy Technology Data Exchange (ETDEWEB)

    Rajendran, R. [BARC Facilities, Bhabha Atomic Research Centre, Kalpakkam, Tamilnadu 603 102 (India)], E-mail: rajurajendr@yahoo.co.in; Prem Sai, K.; Chandrasekar, B. [BARC Facilities, Bhabha Atomic Research Centre, Kalpakkam, Tamilnadu 603 102 (India); Gokhale, A. [Defence Metallurgical Research Laboratory, Kanchanbagh, Hyderabad 500 058 (India); Basu, S. [BARC Facilities, Bhabha Atomic Research Centre, Kalpakkam, Tamilnadu 603 102 (India)

    2008-10-15

    Closed cell aluminum foam is investigated for its impact energy absorption characteristics. For this purpose, a drop hammer of 106 kg was fabricated. A free-fall drop tower was used for the experiments. The hammer was impacted on the rigid foundation with and without aluminium foam at its bottom. Acceleration-time history was recorded for each drop. Deflection of the foam undergoing impact was measured. Compression test was carried out on a foam cylinder to obtain the representative stress-strain diagram from which energy-deflection diagram was derived. Gibson-Ashby's plateau stress-density relation was applied to evaluate the energy-deflection characteristics of foams of different densities, which were eventually applied to the theoretical predictions. Force reduction factor offered by foam is attractive enough to considering, it as the candidate for sacrificial member of the transportation cask.

  9. Characterization of Ti-6Al-4V open cellular foams fabricated by additive manufacturing using electron beam melting

    International Nuclear Information System (INIS)

    Ti-6Al-4V open cellular foams were fabricated by additive manufacturing using electron beam melting (EBM). Foam models were developed from CT-scans of aluminum open cellular foams and embedded in CAD for EBM. These foams were fabricated with solid cell structures as well as hollow cell structures and exhibit tailorable stiffness and strength. The strength in proportion to the measured microindentation hardness is as much as 40% higher for hollow cell (wall) structures in contrast to solid, fully dense EBM fabricated components. Plots of relative stiffness versus relative density were in good agreement with the Gibson-Ashby model for open cellular foam materials. Stiffness or Young's modulus values measured using a resonant frequency-damping analysis technique were found to vary inversely with porosity especially for solid cell wall, open cellular structure foams. These foams exhibit the potential for novel biomedical, aeronautics, and automotive applications.

  10. 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

    2009-01-01

    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.

  11. Styrene-based shape memory foam: fabrication and mathematical modeling

    Science.gov (United States)

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

    2016-10-01

    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 (Shape recovery properties such as shape fixing property and shape recovery ratio were also characterized. In order to provide guidance for the future fabrication of shape memory foam, the theories of Gibson and 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.

  12. STS-100 and Expedition Two Crews Pose For Onboard Portrait

    Science.gov (United States)

    2001-01-01

    STS-100 and Expedition Two crew members pose for an onboard portrait in the Destiny laboratory of the International Space Station (ISS). Bottom, from left, are Chris A. Hadfield of the Canadian Space Agency, Umberto Guidoni of the European Space Agency, Kent V. Rominger, and Susan J. Helms (Expedition Two). Middle row, James S. Voss (Expedition Two), and cosmonauts Yury V. Usachev (Expedition Two) and Yuri V. Lonchakov. Top, Scott E. Parazynski, John L. Phillips, and Jeffrey S. Ashby. The crews accomplished the following objectives: The delivery of the Canadian-built Space Station Remote Manipulator System (SSRMS), Canadarm2, which is needed to perform assembly operations on later flights; The delivery and installation of a UHF anterna that provides space-to-space communications capability for U.S. based space walks; and carried the Italian-built multipurpose Logistics Module Raffaello containing six system racks and two storage racks for the U.S. Lab, Destiny.

  13. Developing scaling relations for the yield strength of nanoporous gold

    Science.gov (United States)

    Briot, Nicolas J.; Balk, T. John

    2015-09-01

    In this work, the applicability of Gibson and Ashby's porous scaling relations to nanoporous metals is discussed, and an updated equation is proposed for relating the yield strength of nanoporous gold to the yield strength of individual gold ligaments that form the porous structure. This new relation is derived from experimental measurements obtained by small-scale tensile testing and by nanoindentation, and incorporates the average ligament diameter. Nanoindentation data, obtained experimentally by the authors as well as reported by others in the literature, are reconciled with tensile test measurements previously reported by the present authors. The values of ligament yield strength calculated with the new scaling relation are found to agree with data reported from mechanical testing of nanowires, and the scaling relation thus represents a bridge between nanowire and nanoporous metal behaviour. In addition, calculations of yield strength for nanoporous gold samples with various ligament size and relative density are consistent with the experimentally determined values.

  14. Rock mechanics. Superplastic nanofibrous slip zones control seismogenic fault friction.

    Science.gov (United States)

    Verberne, Berend A; Plümper, Oliver; de Winter, D A Matthijs; Spiers, Christopher J

    2014-12-12

    Understanding the internal mechanisms controlling fault friction is crucial for understanding seismogenic slip on active faults. Displacement in such fault zones is frequently localized on highly reflective (mirrorlike) slip surfaces, coated with thin films of nanogranular fault rock. We show that mirror-slip surfaces developed in experimentally simulated calcite faults consist of aligned nanogranular chains or fibers that are ductile at room conditions. These microstructures and associated frictional data suggest a fault-slip mechanism resembling classical Ashby-Verrall superplasticity, capable of producing unstable fault slip. Diffusive mass transfer in nanocrystalline calcite gouge is shown to be fast enough for this mechanism to control seismogenesis in limestone terrains. With nanogranular fault surfaces becoming increasingly recognized in crustal faults, the proposed mechanism may be generally relevant to crustal seismogenesis. PMID:25504714

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

    Science.gov (United States)

    Drack, Manfred; Pouvreau, David

    2015-07-01

    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".

  16. Expanding the role of striatal cholinergic interneurons and the midbrain dopamine system in appetitive instrumental conditioning.

    Science.gov (United States)

    Crossley, Matthew J; Horvitz, Jon C; Balsam, Peter D; Ashby, F Gregory

    2016-01-01

    The basal ganglia are a collection of subcortical nuclei thought to underlie a wide variety of vertebrate behavior. Although a great deal is known about the functional and physiological properties of the basal ganglia, relatively few models have been formally developed that have been tested against both behavioral and physiological data. Our previous work (Ashby FG, Crossley MJ. J Cogn Neurosci 23: 1549-1566, 2011) showed that a model grounded in the neurobiology of the basal ganglia could account for basic single-neuron recording data, as well as behavioral phenomena such as fast reacquisition that constrain models of conditioning. In this article we show that this same model accounts for a variety of appetitive instrumental conditioning phenomena, including the partial reinforcement extinction (PRE) effect, rapid and slowed reacquisition following extinction, and renewal of previously extinguished instrumental responses by environmental context cues.

  17. Expanding the role of striatal cholinergic interneurons and the midbrain dopamine system in appetitive instrumental conditioning.

    Science.gov (United States)

    Crossley, Matthew J; Horvitz, Jon C; Balsam, Peter D; Ashby, F Gregory

    2016-01-01

    The basal ganglia are a collection of subcortical nuclei thought to underlie a wide variety of vertebrate behavior. Although a great deal is known about the functional and physiological properties of the basal ganglia, relatively few models have been formally developed that have been tested against both behavioral and physiological data. Our previous work (Ashby FG, Crossley MJ. J Cogn Neurosci 23: 1549-1566, 2011) showed that a model grounded in the neurobiology of the basal ganglia could account for basic single-neuron recording data, as well as behavioral phenomena such as fast reacquisition that constrain models of conditioning. In this article we show that this same model accounts for a variety of appetitive instrumental conditioning phenomena, including the partial reinforcement extinction (PRE) effect, rapid and slowed reacquisition following extinction, and renewal of previously extinguished instrumental responses by environmental context cues. PMID:26467514

  18. Effect of delta-ferrite on the mechanical properties of CF8M stainless steel castings at 4 K

    International Nuclear Information System (INIS)

    A series of five CF8M stainless steel castings, with varying delta-ferrite contents, has been tensile and fracture toughness tested at 4 K. Tensile tests were conducted in the low strain region to establish the initial strain hardening behavior for comparison with two phase deformation theory. It was found that the tensile behavior of the duplex austenite/delta-ferrite structure fits very well with the two phase deformation theory proposed by Ashby. The initial strain hardening rate is determined by the mean-free-path between delta-ferrite particles. Fracture toughness results at 4 K show a decrease in fracture toughness with increasing delta-ferrite content up to approximately 15%; at this point a continuous delta-ferrite crack path is established, and the fracture toughness remains constant with increasing delta-ferrite

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

    DEFF Research Database (Denmark)

    Hansen, Niels

    1977-01-01

    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....... The flow stress-grain size relationship can adequately be expressed by a modified Petch-Hall relation; for 99.999% aluminium material the slope increases with strain through a maximum around 15–20%, whereas for 99.5% aluminium the slope decreases with the strain to zero at strains about 10%. The flow...... 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....

  20. 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)

    2006-12-15

    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.

  1. Transient elastohydrodynamic lubrication film thickness in sliding and rolling line contacts

    International Nuclear Information System (INIS)

    The contact behavior between cam and follower is greatly influenced by the kinematics and dynamics of the whole valve train system. This is the reason that both shape and thickness of the fluid film in the contact gap are mainly determined by applied loads and relative contact speeds as well as the curvatures of contacting elements. Most of the studies about lubricant film behavior between cam and follower have been performed without a consideration of transient effects in the contact gap. For the computational difficulties of transient effects, most contact conditions such as relative contacting speeds have been regarded as quasi-steady state during the whole operating cycle. In this work, in order to obtain stable convergence, a multigrid multi-level method is used for the computation of load capacity in the lubricant film. Nonlinear valve spring dynamics are also considered in the same way as Hanachi's. From the computational results, transient EHL film thicknesses under the conditions of different contact geometries are computed for a pushrod type valve train system during an engine cycle. Several results show the squeeze film effect, which is generally not found with conventional EHL computations of the cam and follower contact. The results are also compared with those by the Dowson-Hamrock (D-H) formula, which does not consider the dynamic film effect. Without the dynamic film effect as in D-H's formula, the minimum film thickness is highly dependent on the entraining lubricant velocity, whereas the minimum film thickness including the squeeze film effect is dependent on the applied load

  2. 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

    2012-04-01

    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

  3. Characterization of cellular titanium for biomedical applications

    Science.gov (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

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

    Directory of Open Access Journals (Sweden)

    González, R.

    2001-12-01

    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

  5. Modeling of contact theories for the manipulation of biological micro/nanoparticles in the form of circular crowned rollers based on the atomic force microscope

    International Nuclear Information System (INIS)

    This article has dealt with the development and modeling of various contact theories for biological nanoparticles shaped as cylinders and circular crowned rollers for application in the manipulation of different biological micro/nanoparticles based on Atomic Force Microscope. First, the effective contact forces were simulated, and their impact on contact mechanics simulation was investigated. In the next step, the Hertz contact model was simulated and compared for gold and DNA nanoparticles with the three types of spherical, cylindrical, and circular crowned roller type contact geometries. Then by reducing the length of the cylindrical section in the circular crowned roller geometry, the geometry of the body was made to approach that of a sphere, and the results were compared for DNA nanoparticles. To anticipatory validate the developed theories, the results of the cylindrical and the circular crowned roller contacts were compared with the results of the existing spherical contact simulations. Following the development of these contact models for the manipulation of various biological micro/nanoparticles, the cylindrical and the circular crowned roller type contact theories were modeled based on the theories of Lundberg, Dowson, Nikpur, Heoprich, and Hertz for the manipulation of biological micro/nanoparticles. Then, for a more accurate validation, the results obtained from the simulations were compared with those obtained by the finite element method and with the experimental results available in previous articles. The previous research works on the simulation of nanomanipulation have mainly investigated the contact theories used in the manipulation of spherical micro/nanoparticles. However since in real biomanipulation situations, biological micro/nanoparticles of more complex shapes need to be displaced in biological environments, this article therefore has modeled and compared, for the first time, different contact theories for use in the biomanipulation of

  6. 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

    2012-06-01

    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

  7. What is Optimum Variability?

    Science.gov (United States)

    Schuldberg, David

    2015-10-01

    Guastello (2015a) opened the call for articles for this issue with Goldberger (1991) and colleagues' findings of chaotic variability in healthy heart rate, noting, 'the principle of healthy variability has extended to other biomedical and psychological phenomena.' He suggests a dialectical underpinning for optimal variability involving 'a combination of the minimum entropy or free energy principle that pushes in a downward direction, and Ashby's Law of Requisite Variety that pushes in an upward direction.' Each of the papers in this issue addresses optimal variability across a variety of health-related areas. The present article surveys these seven papers in relation to five conceptual questions about optimal variability: (a) Is variability a positive or a negative, and how are positive things related to health? (b) How shall we define and measure variability? (c) What constitutes an optimum, and how do we locate one? (d) What is the relationship between optimum variability and health? Finally, it touches on (e) What are underlying principles and phenomena behind healthy variability, and can they inform our vocabulary for health? The paper concludes by discussing practical approaches to dealing with optimization. PMID:26375940

  8. 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.

    Science.gov (United States)

    Sironic, Amanda; Reeve, Robert A

    2015-12-01

    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. PMID:25984636

  9. 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: debora_hara@yahoo.com.br [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

    2015-07-01

    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)

  10. Morphology change of Mg2Si and strength change in a long isothermal holding test and a long continuous cooling test in Al-Mg-Si alloy

    International Nuclear Information System (INIS)

    We investigated high temperature strength change of Mg2Si precipitate hardening type aluminum alloy with TEM observation as light material for a fuel cask. We tested strength changes during both an isothermal holding test at 230degC and a continuous cooling test from 226degC to 191degC up to 10.0 kh. In the isothermal holding test Mg2Si was rod like precipitate parallel to Al and showed like Ostwald ripening. In the continuous cooling test the kinetics of Mg2Si growing can also be explained by an extensive Ostwald ripening theory. In the isothermal holding test high temperature strength gradually decreased. But in the continuous cooling test the strength turned to increase after 3.0 kh. From Ashby's precipitate hardening theory we can consider that is because that the decrease of Mg2Si precipitate hardening effect is smaller than the increase of matrix strengthening with decrease of temperature after 3.0 kh. (author)

  11. 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

    2011-01-01

    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.

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

    International Nuclear Information System (INIS)

    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

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

    Directory of Open Access Journals (Sweden)

    J. Kováčik

    2016-03-01

    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.

  14. 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

    2009-07-01

    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.

  15. Perceived association between diagnostic and non-diagnostic cues of women's sexual interest: General Recognition Theory predictors of risk for sexual coercion.

    Science.gov (United States)

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

    2010-01-01

    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.

  16. Starch-based extruded cereals enriched in fibers: a behavior of composite solid foams.

    Science.gov (United States)

    Chanvrier, Hélène; Desbois, Fabrice; Perotti, Fabienne; Salzmann, Claire; Chassagne, Sophie; Gumy, Jean-Claude; Blank, Imre

    2013-10-15

    Extruded cereals mainly composed of starch and enriched in fibers were produced with two types of base recipes: (i) one recipe mainly composed of wheat flour and (ii) one recipe mainly composed of corn and soya flours. The addition of fibers was performed through the use of oat bran concentrate or wheat bran, up to 32% of the recipe. The structure of the extrudates, assessed by X-ray tomography, pointed out the decrease of porosity and of mean cells size with the increase of the total dietary fibers content of the recipe. The hardness of the products, i.e. the maximum stress determined by a compression test, was linked to their porosity. The Gibson-Ashby relationship could be applied and the fit was even improved when considering the walls of the solid foam as composite materials. Fibers and proteins can be indeed considered as particles dispersed in the starchy phase. This work thus shows the impact of the structure of the extrudates on their mechanical properties. The structure is taken into account at different length scales; at the level of the porous structure and at the level of the phase of the main biopolymers present in the recipe (starch, proteins and fibers). The mechanical behavior of these products is then discussed according to their characteristics of composite solid foams. PMID:23987420

  17. Mechanical and Numerical Analysis Concerning Compressive Properties of Tin-Lead Open-Cell Foams

    Science.gov (United States)

    Belhadj, Abd-Elmouneïm; Gavrus, Adinel; Bernard, Fabrice; Azzaz, Mohammed

    2015-10-01

    The design of new or innovative materials has to meet two essential criteria: increased mechanical performance and minimization of the mass. This dual requirement leads to interest in the study of various classes of metallic foams. The actual research is focused on open-cell Tin-Lead foams manufactured by replication process using NaCl preform. A mechanical press equipped with a load cell and a local extensometer with a controlled deformation rate is used. Experimental tests were carried out in order to study the influences of both the cell size and of the relative density on the mechanical behavior during a compression deformation and to analyze the obtained properties variation within a new framework. This study has three main sections which start with the manufacturing description and mechanical characterization of the proposed metallic foams followed by the understanding and modeling of their response to a compression load via a Gibson-Ashby model, a Féret law, a proposed simple Avrami model, and a generalized Avrami model. Finally, an exposition of a numerical simulation analyzing the compression of the Sn-Pb foams concerning the variation of the relative densities with respect to the plastic strain is proposed.

  18. Vispārējā pašcieņa, atkarīgā pašcieņa un perfekcionisms sievietēm un vīriešiem

    OpenAIRE

    Brence, Iveta

    2016-01-01

    Pētījuma mērķis bija izpētīt, kādas sakarības starp vispārējo pašcieņu, atkarīgo pašcieņu un perfekcionismu vērojamas sieviešu un vīriešu grupās, kā arī, vai novērojamas dzimumatšķirības vispārējās pašcieņas, atkarīgās pašcieņas un perfekcionisma rādītājos. Datu ievākšanai tika izmantotas 3 aptaujas: Perfekcionisma aptauja (Almost Perfect Scale-Revised Short Form, Slaney, Mobley, Trippi, Ashby, & Johnson, 1996; Latvijā aptauju adaptējusi Renāte Buliņa 2009. gadā); Rozenberga pašcieņas aptauja...

  19. Mechanical, electrical and micro-structural properties of La0.6Sr0.4Co0.2Fe0.8O3 perovskite-based ceramic foams

    International Nuclear Information System (INIS)

    Mechanical, electrical and micro-structural properties of new electronic conducting ceramic foams are reported. Ceramic foams are prepared using the slurry of La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) by the polymeric sponge method, which is followed by spray coating for increasing the number of coatings-sinterings on polyurethane foams of 30, 45 and 60 ppi (pores per linear inch). An increase in the number of coatings-sinterings and ppi improved the compressive strength, density and electrical conductivity by decreasing the porosity to ∼76%, as also observed by the SEM study. The three-times coated-sintered ceramic foams (60 ppi) exhibited optimum values of compressive strength of ∼1.79 MPa and relative density of ∼0.24 at 25 deg. C and electrical conductivity of ∼22 S cm-1 at 600 deg. C with an activation energy of ∼0.22 eV indicating its suitability as a solid oxide fuel cell current collector. The experimental results are discussed in terms of the Gibson and Ashby theoretical model. (fast track communication)

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

    International Nuclear Information System (INIS)

    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/cm3 were studied in casting and thermally induced, fine-grain matrix microstructures. Test samples of the composites were compressed at a 10−3 s−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 (σmax) 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 (σp): 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 (σmax, LYP, and σp)

  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

    2009-04-01

    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. Rate-controlling mechanisms of hot deformation in a medium carbon vanadium microalloy steel

    International Nuclear Information System (INIS)

    Isothermal compression tests were carried out on a medium carbon vanadium microalloy steel (roughly Fe-0.33C-1.5Mn-0.1 V, wt%) by using a Gleeble-1500 simulator. Based on constitutive analysis including an Arrhenius term, activation energy for hot working was calculated and used to evaluate the rate-controlling mechanism of hot deformation. At low strain rates (0.1–1 s−1), the activation energy for hot working (287.4 kJ/mol) is very close to the austenite lattice self-diffusion activation energy, indicating that the rate-controlling mechanism is dislocation climb. While at high strain rates (10–30 s−1), the activation energy becomes very high (500.6 kJ/mol), and activation volume is better used under such conditions. Then, activation volume analysis based on both Schöck model and Kocks–Argon–Ashby model demonstrates that the rate-controlling mechanism at high strain rates is cross slip. That is, the rate-controlling mechanisms of hot deformation for the medium carbon vanadium microalloy steel at high and low strain rates are intrinsically different. Inspired by the findings above, processing map analysis based on dynamic materials model was further preceded and different peak domains of power dissipation efficiency in high and low strain rate regimes were found.

  3. Thermal stability of interface voids in Cu grain boundaries with molecular dynamic simulations

    Science.gov (United States)

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

    2016-09-01

    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.

  4. Perfectionism, shame, and self-concept in dancers: a mediation analysis.

    Science.gov (United States)

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

    2014-01-01

    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.

  5. 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

    Science.gov (United States)

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

    2016-05-01

    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).

  6. A molecular dynamics study of void initiation and growth in monocrystalline and nanocrystalline copper

    Science.gov (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.

  7. Mechanical Properties of Shock-Damaged Rocks

    Science.gov (United States)

    He, Hongliang; Ahrens, T. J.

    1994-01-01

    Stress-strain tests were performed both on shock-damaged gabbro and limestone. The effective Young's modulus decreases with increasing initial damage parameter value, and an apparent work-softening process occurs prior to failure. To further characterize shock-induced microcracks, the longitudinal elastic wave velocity behavior of shock-damaged gabbro in the direction of compression up to failure was measured using an acoustic transmission technique under uniaxial loading. A dramatic increase in velocity was observed for the static compressive stress range of 0-50 MPa. Above that stress range, the velocity behavior of lightly damaged (D(sub 0) less than 0.1) gabbro is almost equal to unshocked gabbro. The failure strength of heavily-damaged (D(sub 0) greater than 0.1) gabbro is approx. 100-150 MPa, much lower than that of lightly damaged and unshocked gabbros (approx. 230-260 MPa). Following Nur's theory, the crack shape distribution was analyzed. The shock-induced cracks in gabbro appear to be largely thin penny-shaped cracks with c/a values below 5 x 10(exp -4). Moreover, the applicability of Ashby and Sammis's theory relating failure strength and damage parameter of shock-damaged rocks was examined and was found to yield a good estimate of the relation of shock-induced deficit in elastic modulus with the deficit in compressive strength.

  8. Investigation of Macroscopic Brittle Creep Failure Caused by Microcrack Growth Under Step Loading and Unloading in Rocks

    Science.gov (United States)

    Li, Xiaozhao; Shao, Zhushan

    2016-07-01

    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.

  9. Environmental health impacts: occurrence, exposure and significance, Lancaster University, UK, 9-10 September 2003.

    Science.gov (United States)

    Martin, Francis L; Semple, Kirk T

    2004-09-01

    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.

  10. The STS-93 crew pose in front of Columbia

    Science.gov (United States)

    1999-01-01

    The STS-93 crew pose in front of the Space Shuttle orbiter Columbia following their landing on runway 33 at the Shuttle Landing Facility. Main gear touchdown occurred at 11:20:35 p.m. EDT on July 27. From left to right, they are Mission Specialists Catherine G. Coleman (Ph.D.) and Stephen A. Hawley (Ph.D.), Pilot Jeffrey S. Ashby, Commander Eileen Collins, and Mission Specialist Michel Tognini of France, with the Centre National d'Etudes Spatiales (CNES). The mission's primary objective was to deploy 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. This was the 95th flight in the Space Shuttle program and the 26th for Columbia. The landing was the 19th consecutive Shuttle landing in Florida and the 12th night landing in Shuttle program history. On this mission, Collins became the first woman to serve as a Shuttle commander.

  11. STS-100 crew members pose on the FSS after emergency escape training on the pad

    Science.gov (United States)

    2001-01-01

    KENNEDY SPACE CENTER, Fla. - The STS-100 crew poses for a photo on the 195-foot level of Launch Pad 39A'''s Fixed Service Structure. Standing, from left, are Mission Specialists Scott Umberto Guidoni, Scott E. Parazynski, Chris A. Hadfield, Yuri V. Lonchakov, and John L. Phillips; Commander Kent V. Rominger; and Pilot Jeffrey S. Ashby. Hadfield is with the Canadian Space Agency, Guidoni with the European Space Agency and Lonchakov with the Russian Aviation and Space Agency. Behind them can be seen the tip of one white solid rocket booster and the orange external tank. The STS-100 mission is carrying the Multi-Purpose Logistics Module Raffaello and the 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. Launch of mission STS-100 is scheduled for April 19 at 2:41 p.m. EDT from Launch Pad 39A.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-04-01

    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.

  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

    2003-04-01

    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. Mechanisms-based viscoplasticity: Theoretical approach and experimental validation for steel 304L.

    Science.gov (United States)

    Zubelewicz, Aleksander; Oliferuk, Wiera

    2016-01-01

    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. PMID:27026209

  15. Effect of pressure on the strength of olivine at room temperature

    Science.gov (United States)

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

    2016-10-01

    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.

  16. An experimental search for gamma radiation associated with thunderstorm activity

    International Nuclear Information System (INIS)

    This experiment is a repeat of an earlier experiment, but with more sensitive apparatus and in a location with a higher incidence of thunderstorm activity. The earlier experiment was undertaken by Ashby and Whitehead to investigate the theory that ball lightning might be associated with the annihilation of small amounts of antimatter, and it yielded some very interesting but inconclusive results. In the course of about 12 months of data taking, four high rate bursts of gamma radiation were detected. These events lasted a few seconds and had many thousands of counts (16500, 5000, 3700, and > 7700. Unfortunately, the association of these gamma ray bursts with thunderstorms or ball lightning was not clearly established, although one of the bursts did occur during a local thunderstorm in rough coincidence with a lightning bolt striking a flagpole about 100 yards from the gamma ray detection crystals. A pulse height spectrum taken for this burst (no spectrum was taken for the other three) exhibited a significant peak, well above background, the energy of which appeared to be compatible with the 511 keV positron annihilation line. While the peak could not be unambiguously attributed to positron annihilation, this certainly appeared to be the most likely source

  17. Rate-controlling mechanisms of hot deformation in a medium carbon vanadium microalloy steel

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Haitao [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Liu, Guoquan, E-mail: g.liu@ustb.edu.cn [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); State Key Laboratory for Advanced Metals and Materials, University of Science and Technology Beijing, Beijing 100083 (China); Xu, Lei [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Hebei Iron and Steel Technology Research Institute, Shijiazhuang 050021 (China)

    2013-01-01

    Isothermal compression tests were carried out on a medium carbon vanadium microalloy steel (roughly Fe-0.33C-1.5Mn-0.1 V, wt%) by using a Gleeble-1500 simulator. Based on constitutive analysis including an Arrhenius term, activation energy for hot working was calculated and used to evaluate the rate-controlling mechanism of hot deformation. At low strain rates (0.1-1 s{sup -1}), the activation energy for hot working (287.4 kJ/mol) is very close to the austenite lattice self-diffusion activation energy, indicating that the rate-controlling mechanism is dislocation climb. While at high strain rates (10-30 s{sup -1}), the activation energy becomes very high (500.6 kJ/mol), and activation volume is better used under such conditions. Then, activation volume analysis based on both Schoeck model and Kocks-Argon-Ashby model demonstrates that the rate-controlling mechanism at high strain rates is cross slip. That is, the rate-controlling mechanisms of hot deformation for the medium carbon vanadium microalloy steel at high and low strain rates are intrinsically different. Inspired by the findings above, processing map analysis based on dynamic materials model was further preceded and different peak domains of power dissipation efficiency in high and low strain rate regimes were found.

  18. Comparison of Frictional Heating Models

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-10-01

    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.

  19. 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: pejr2@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge New Museums Site, Pembroke Street, Cambridge, CB2 3QZ (United Kingdom)

    2013-07-25

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Ilina, Elena

    2010-07-01

    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

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

    International Nuclear Information System (INIS)

    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

  2. Root nodule bacteria from Clitoria ternatea L. are putative invasive nonrhizobial endophytes.

    Science.gov (United States)

    Aeron, Abhinav; Chauhan, Puneet Singh; Dubey, Ramesh Chand; Maheshwari, Dinesh Kumar; Bajpai, Vivek K

    2015-02-01

    In this study, bacteria (8 species and 5 genera) belonging to the classes Betaproteobacteria, Gammaproteobacteria, and Sphingobacteria were isolated from root nodules of the multipurpose legume Clitoria ternatea L. and identified on the basis of partial 16S rRNA sequencing. The root nodule bacteria were subjected to phenotypic clustering and diversity studies using biochemical kits, including Hi-Media Carbokit™, Enterobacteriaceae™ identification kit, ERIC-PCR, and 16S ARDRA. All the strains showed growth on Ashby's N-free media over 7 generations, indicative of presumptive nitrogen fixation and further confirmed by amplification of the nifH gene. None of the strains showed the capability to renodulate the host plant, neither alone nor in combination with standard rhizobial strains, which was further confirmed by the absence of nodC bands in PCR assay. The results clearly indicate the common existence of nonrhizobial microflora inside the root nodules of legumes, which were thought to be colonized only by rhizobia and were responsible for N2 fixation in leguminous crops. However, with the recent discovery of nodule endophytes from a variety of legumes, as also observed here, it can be assumed that symbiotic rhizobia are not all alone and that these invasive endophytes belonging to various bacterial genera are more than just opportunistic colonizers of specialized nodule niche. PMID:25619106

  3. [Screening and identification of indoleacetic acid producing endophytic bacterium in Panax ginseng].

    Science.gov (United States)

    Jiang, Yun; Tian, Lei; Chen, Chang-qing; Zhang, Guan-jun; Li, Tong; Chen, Jing-xiu; Wang, Xue

    2015-01-01

    Endophytic bacteria which was producing indoleacetic acid was screened from Panax ginseng by using the Salkowski method. The active strain was also tested for its ability of nitrogen fixation by using the Ashby agar plates, the PKV plates and quantitative analysis of Mo-Sb-Ascrobiology acid colorimetry was used to measure its ability of phosphate solubilization, for its ability of potassium solubilization the silicate medium and flame spectrophotometry was used, for its ability of producing siderophores the method detecting CAS was used, for its ability of producing ACC deaminase the Alpha ketone butyric acid method was applied. And the effect on promoting growth of seed by active strain was tested. The results showed that the indoleacetic acid producing strain of JJ5-2 was obtained from 118 endophytes, which the content of indoleacetic acid was 10.2 mg x L(-1). The JJ5-2 strain also had characteristics of phosphate and potassium solubilization, nitrogen fixation, producing siderophores traits, and the promoting germination of ginseng seeds. The JJ5-2 strain was identified as Bacillus thuringiensis by analyzing morphology, physiological and biochemical properties and 16S rRNA gene sequences. PMID:26080547

  4. 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

    2004-12-15

    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)

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

    Science.gov (United States)

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

    2016-05-01

    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. PMID:27067311

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

    Energy Technology Data Exchange (ETDEWEB)

    Aragon-Lezama, J.A., E-mail: alja@correo.azc.uam.mx [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: a.garciaborquez@yahoo.com.mx [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: gtorres@unam.mx [Departamento de Metálicos y Cerámicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Apdo., P 70-360, México, D.F., México (Mexico)

    2015-06-25

    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})

  7. 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.

    Science.gov (United States)

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

    2014-12-01

    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.

  8. STS-112 Flight Day 4 Highlights

    Science.gov (United States)

    2002-10-01

    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.

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

    Directory of Open Access Journals (Sweden)

    Birgit eStürmer

    2011-11-01

    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.

  10. Bioflocculant exopolysaccharide production by Azotobacter indicus using flower extract of Madhuca latifolia L.

    Science.gov (United States)

    Patil, Satish V; Salunkhe, Rahul B; Patil, Chandrashekhar D; Patil, Deepak M; Salunke, Bipinchandra K

    2010-10-01

    Efficacy of Azotobacter indicus ATCC 9540 strain for production exopolysaccharide (EPS) bioflocculant was investigated. Mahua flower extract (Madhuca latifolia L), a natural substrate at the concentration of 20 g L(-1), gave maximum recovery of EPS followed by sucrose and mannitol as compared to other carbon sources after 172 h. Yeast extract was found to be the most effective nitrogen source as compared to beef extract, sodium nitrate, ammonium sulfate, casein hydrolysate, and urea for the production of EPS. EPS production was increased in presence of nitrogen (5.51 g L(-1)) as compared to nitrogen-free medium (3.51 g L(-1)), and fermentation time was also reduced by 28 h. Maximum EPS production (6.10 g L(-1)) was found in the presence of 20 g L(-1) flower extract and 0.5 g L(-1) yeast extract containing Ashby's media with 180 rpm at 30 degrees C at 144 h, under controlled conditions in 2.5 L fermenter using optimized medium. The isolated EPS showed cation-dependent flocculating activity. Concentration of EPS played an important role in bioflocculating activity which increased in a concentration-dependent manner up to a certain limit, with the maximum flocculation of 72% at 500 mg L(-1) concentration but remained almost static after this concentration. Extracted polymer was characterized by different chemical tests, FT-IR spectroscopy, and TLC which showed presence of uronic acids, O-acetyl groups, and Orcinol with suggestive indication of alginate like polymer. This study suggests that use of M. latifolia L. flowers can be a potential alternative bioresource for production of exopolysaccharide. PMID:19921493

  11. THE MACHINERY OF TIME MOVED TO IMAGINATION: RPG AND EMPATHY IN HISTORIC HISTORY OF EDUCATION

    Directory of Open Access Journals (Sweden)

    Juliano Pereira da Silva

    2014-12-01

    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.

  12. Biological control of fruit flies (Diptera: Tephritidae) through parasitoid augmentative releases: Current status

    International Nuclear Information System (INIS)

    Fruit flies are among the main pests affecting the world fruit industry (Aluja 1993). Bait sprays have traditionally been used successfully to control them; however, the side effects on the environment and health hazards commonly associated with pesticides, have resulted in strong public opposition to the use of bait sprays. This is particularly so when sprays are applied in urban areas or in coffee plantations where, although Medflies are present, they do not pose a danger to crops. Alternative methods that are effective and environmental friendly to suppress fruit fly populations are highly desirable. Biological control, the use of natural enemies to suppress pest populations, represents such an alternative. Some of the most successful cases of biological control are the control of Iceria purchasi Maskell (Homoptera: Margarodidae) by Rodolia cardinalis Mulsant (Coleoptera: Coccinellidae) in California (De Bach 1968, van den Bosch et al. 1982), and the control of Aleurocanthus woglumi Ashby (Homoptera: Aleyrodidae) mainly by Encarsia (=Prospaltella) opulenta Silv. (Hymenoptera: Aphelinidae) in Mexico (Jimenez 1961, 1971), both using the classical approach. However, this approach has been limited to certain conditions of environmental stability and biodiversity which are only found in a few ecosystems. Other factors, such as types of pests, the economic threshold and product quality requirements represent additional limitations. The best option in many cases could be augmentative biological control, which could overcome some of the deficiencies of the classical approach (Sivinski 1996). According to Knipling (1992) and Barclay (1987), augmentative biological control can be considered as a formal alternative for suppressing pest populations and even for use in eradication programmes, after integration with the sterile insect technique (SIT). In this approach, mass production of natural enemies is required and this production has to be cost effective

  13. Incorporating damage mechanics into explosion simulation models

    International Nuclear Information System (INIS)

    The source region of an underground explosion is commonly modeled as a nested series of shells. In the innermost open-quotes hydrodynamic regimeclose quotes pressures and temperatures are sufficiently high that the rock deforms as a fluid and may be described using a PVT equation of state. Just beyond the hydrodynamic regime, is the open-quotes non-linear regimeclose quotes in which the rock has shear strength but the deformation is nonlinear. This regime extends out to the open-quotes elastic radiusclose quotes beyond which the deformation is linear. In this paper, we develop a model for the non-linear regime in crystalline source rock where the nonlinearity is mostly due to fractures. We divide the non-linear regime into a open-quotes damage regimeclose quotes in which the stresses are sufficiently high to nucleate new fractures from preexisting ones and a open-quotes crack-slidingclose quotes regime where motion on preexisting cracks produces amplitude dependent attenuation and other non-linear effects, but no new cracks are nucleated. The boundary between these two regimes is called the open-quotes damage radius.close quotes The micromechanical damage mechanics recently developed by Ashby and Sammis (1990) is used to write an analytic expression for the damage radius in terms of the initial fracture spectrum of the source rock, and to develop an algorithm which may be used to incorporate damage mechanics into computer source models for the damage regime. Effects of water saturation and loading rate are also discussed

  14. Adaptive and Rational Anticipations in Risk Management Systems and Economy

    Science.gov (United States)

    Dubois, Daniel M.; Holmberg, Stig C.

    2010-11-01

    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

  15. The strength of heterogeneous volcanic rocks: A 2D approximation

    Science.gov (United States)

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

    2016-06-01

    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

  16. 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

    2004-01-01

    [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.

  17. Working with "rookies": A case study of science teachers mentors

    Science.gov (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

  18. Carbon Sequestration on Surface Mine Lands

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-03-31

    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

  19. The Time Is Now: Bioethics and LGBT Issues.

    Science.gov (United States)

    Powell, Tia; Foglia, Mary Beth

    2014-09-01

    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. PMID:25231781

  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)

    2014-01-01

    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. 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: mameyers@ucsd.edu

    2008-09-15

    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

  2. The Time Is Now: Bioethics and LGBT Issues.

    Science.gov (United States)

    Powell, Tia; Foglia, Mary Beth

    2014-09-01

    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.

  3. NASA Managers Set July 20 As Launch Date for Chandra Telescope

    Science.gov (United States)

    1999-07-01

    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 domo@hq.nasa.gov. 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

  4. 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)

    2014-01-01

    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 .%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。

  5. Numerical and experimental study of creep of grade 91 steel at high temperature

    International Nuclear Information System (INIS)

    Grade 91 steel is a suitable candidate for structural components of the secondary and the vapour of the generation IV nuclear reactors. Their in-service lifetime will be extended to 60 years. It is necessary to consider the mechanisms involved-term during long creep to propose more reliable predictions of creep lifetimes. Necking is the main failure mechanism for creep lifetimes up to 160 kh at 500 C and 94 kh at 600 C. Necking modelling including the material creep softening leads to two bound laws including experimental lifetimes of a large number of tempered martensitic steels loaded up to 200 kh at temperature 500-700 C. The observed creep intergranular cavities are shown to affect very weekly creep strain rate. The prediction of the cavity evolution will allow estimating creep lifetimes out of experimental data domain. Their nucleation and growth, supposed to be associated to vacancy diffusion, are modelled using two classical models. The first one considers instantaneous nucleation (Raj and Ashby) and the second one continuous nucleation obeying the Dyson law (Riedel). The second one leads to two bound laws, more stable with respect to the parameter values. It allows predicting final sizes of cavities in reasonable agreement with the measured ones. Nevertheless, nucleation rate should be estimated from measured cavity densities. Nucleation of cavities by diffusion is simulated using the Raj model. This model does not allow predicted final cavity densities in agreement with the measured ones, even by considering cavity nucleation at precipitates/Laves interfaces experimentally observed and the maximum local stress concentration of a factor 2 computed using finite element calculation in a 2D plane strain hypothesis based on either simulated or real microstructures containing triple points or precipitates/Laves phases. The use of the Dyson law allows us to propose predictions of long-term creep lifetimes. Lifetime predicted using the diffusion-induced growth

  6. 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

    2012-04-01

    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

  7. 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)

    李琳瑛

    2011-01-01

    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

  8. 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

    2014-12-01

    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

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

    Institute of Scientific and Technical Information of China (English)

    WEI; Yueguang

    2001-01-01

    [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

  10. Compression perpendicular-to-grain behaviour of wood

    Science.gov (United States)

    Tabarsa, Taghi

    The major objective of this study was to provide a better understanding on compression perpendicular-to-grain behaviour of wood and to examine the capability of mechanical models for predicting this behaviour. A new test procedure for testing wood behaviour in compression was developed which enabled the collection of load-deformation data and recording of cellular structure images in real time. To understand the relation between cellular structure deformation and load-deformation behaviour of wood in transverse compression, specimens of four species which have different structure (two softwoods: white spruce and jack pine, two hardwoods: white ash and aspen) were subjected to radial compression. Results showed that, in softwoods under radial compression, bending of cell walls occur. Bending deformation was distributed non-uniformly in a growth ring. The largest deformation occurred in the weakest zone in earlywood which led to the first collapse in this zone. Collapse then developed toward latewood. At the load level used in this study, latewood layer did not collapse. Corresponding images recorded in real time and stress-strain curve showed that the plateau region is a reflection of cell lumen removal in earlywood and the upward part at the end of stress-strain curve is related to elastic behaviour of latewood layer. In hardwoods, the mechanisms were different. In ring porous white ash, first collapse occurred in large vessels located in earlywood, but in diffuse porous aspen, first collapse occurred in vessels aligned near each other. In tangential compression of softwood, it was found that the mechanism of deformation in tangential compression was dominated by buckling of latewood layers. It was concluded that different mechanical models should be developed for wood behaviour in tangential compression based on the mechanism of latewood layer buckling. In this study the applicability of some of the mechanical models developed by Gibson and Ashby (1982) were

  11. 知道与不知道要学多少:类别学习中样例量的预期作用%The Expectation Effect of the Sample Size in Category Learning

    Institute of Scientific and Technical Information of China (English)

    刘志雅; 黄艳利; Carol A.Seger

    2012-01-01

    采用“5/4模型”类别结构探讨了类别学习中样例量的预期作用.设置了两种学习条件(“知道样例量”和“不知道样例量”),分别探讨两种学习条件下的学习效率、学习策略以及所形成的类别表征.106名大学生参加了实验,结果表明:在类别学习中,样例量的预期作用显著,知道样例量组的学习效率高于不知道样例量组;样例量的预期作用对类别学习效率的影响是通过影响学习过程中使用的策略来实现的;样例量的预期作用不影响两种学习条件的学习后形成的类别表征,且两种学习条件的被试自始至终表现出样例学习的表征模式.%This paper explores the effects of category size expectations on category learning. The expectation effect is the finding that category learning is improved when subjects are told how many items or exemplars are in each category in advance. There are three major theories or models of how categories are represented: Rule-based, Prototype-based, and Exemplar-based. Rule-based models assume that category learning is a process of discovering an explicit, verbalizable rule that maximizes categorization accuracy (Ashby, 2005; Seger & Cincotta, 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). According to Rule-based and Prototype-based models, people the rule or prototype as their final representation without regard to the total number of exemplars in each relevant category

  12. EDITORIAL: Special issue on applied neurodynamics: from neural dynamics to neural engineering Special issue on applied neurodynamics: from neural dynamics to neural engineering

    Science.gov (United States)

    Chiel, Hillel J.; Thomas, Peter J.

    2011-12-01

    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