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Sample records for acetivorans strain c2a

  1. Carbon-dependent control of electron transfer and central carbon pathway genes for methane biosynthesis in the Archaean, Methanosarcina acetivorans strain C2A

    Gunsalus Robert P

    2010-02-01

    Full Text Available Abstract Background The archaeon, Methanosarcina acetivorans strain C2A forms methane, a potent greenhouse gas, from a variety of one-carbon substrates and acetate. Whereas the biochemical pathways leading to methane formation are well understood, little is known about the expression of the many of the genes that encode proteins needed for carbon flow, electron transfer and/or energy conservation. Quantitative transcript analysis was performed on twenty gene clusters encompassing over one hundred genes in M. acetivorans that encode enzymes/proteins with known or potential roles in substrate conversion to methane. Results The expression of many seemingly "redundant" genes/gene clusters establish substrate dependent control of approximately seventy genes for methane production by the pathways for methanol and acetate utilization. These include genes for soluble-type and membrane-type heterodisulfide reductases (hdr, hydrogenases including genes for a vht-type F420 non-reducing hydrogenase, molybdenum-type (fmd as well as tungsten-type (fwd formylmethanofuran dehydrogenases, genes for rnf and mrp-type electron transfer complexes, for acetate uptake, plus multiple genes for aha- and atp-type ATP synthesis complexes. Analysis of promoters for seven gene clusters reveal UTR leaders of 51-137 nucleotides in length, raising the possibility of both transcriptional and translational levels of control. Conclusions The above findings establish the differential and coordinated expression of two major gene families in M. acetivorans in response to carbon/energy supply. Furthermore, the quantitative mRNA measurements demonstrate the dynamic range for modulating transcript abundance. Since many of these gene clusters in M. acetivorans are also present in other Methanosarcina species including M. mazei, and in M. barkeri, these findings provide a basis for predicting related control in these environmentally significant methanogens.

  2. Identification and characterization of arsenite methyltransferase from an archaeon, Methanosarcina acetivorans C2A.

    Wang, Pei-Pei; Sun, Guo-Xin; Zhu, Yong-Guan

    2014-11-01

    Arsenic is a ubiquitous toxic contaminant in the environment. The methylation of arsenic can affect its toxicity and is primarily mediated by biological processes. Few studies have focused on the mechanism of arsenic methylation in archaea although archaea are widespread in the environment. Here, an arsenite [As(III)] methyltransferase (ArsM) was identified and characterized from an archaeon Methanosarcina acetivorans C2A. Heterologous expression of MaarsM was shown to confer As(III) resistance to an arsenic-sensitive strain of E. coli through arsenic methylation and subsequent volatilization. Purified MaArsM protein was further identified the function in catalyzing the formation of various methylated products from As(III) in vitro. Methylation of As(III) by MaArsM is highly dependent on the characteristics of the thiol cofactors used, with some of them (coenzyme M, homocysteine, and dithiothreitol) more efficient than GSH. Site-directed mutagenesis demonstrated that three conserved cysteine (Cys) residues (Cys62, Cys150, and Cys200) in MaArsM were necessary for As(III) methylation, of which only Cys150 and Cys200 were required for the methylation of monomethylarsenic. These results present a molecular pathway for arsenic methylation in archaea and provide some insight into the role of archaea in As biogeochemistry. PMID:25295694

  3. Genetic, physiological and biochemical characterization of multiple methanol methyltransferase isozymes in Methanosarcina acetivorans C2A.

    Pritchett, Matthew A; Metcalf, William W

    2005-06-01

    Biochemical evidence suggests that methanol catabolism in Methanosarcina species requires the concerted effort of methanol:5-hydroxybenzimidazolylcobamide methyltransferase (MtaB), a corrinoid-containing methyl-accepting protein (MtaC) and Co-methyl-5-hydroxybenzimidazolylcobamide:2-mercapto-ethanesulphonic acid methyltransferase (MtaA). Here we show that Methanosarcina acetivorans possesses three operons encoding putative methanol-specific MtaB and corrinoid proteins: mtaCB1, mtaCB2 and mtaCB3. Deletion mutants lacking the three operons, in all possible combinations, were constructed and characterized. Strains deleted for any two of the operons grew on methanol, whereas strains lacking all three did not. Therefore, each operon encodes a bona fide methanol-utilizing MtaB/corrinoid protein pair. Most of the mutants were similar to the wild-type strain, with the exception of the DeltamtaCB1 DeltamtaCB2 double mutant, which grew more slowly and had reduced cell yields on methanol medium. However, all mutants displayed significantly longer lag times when switching from growth on trimethylamine to growth on methanol. This indicates that all three operons are required for wild-type growth on methanol and suggests that each operon has a distinct role in the metabolism of this substrate. The combined methanol:CoM methyltransferase activity of strains carrying only mtaCB1 was twofold higher than strains carrying only mtaCB2 and fourfold higher than strains carrying only mtaCB3. Interestingly, the presence of the mtaCB2 and mtaCB3 operons, in addition to the mtaCB1 operon, did not increase the overall methyltransferase activity, suggesting that these strains may be limited by MtaA availability. All deletion mutants were unaffected with respect to growth on trimethylamine and acetate corroborating biochemical evidence indicating that each methanogenic substrate has specific methyltransfer enzymes. PMID:15882413

  4. Physiology and posttranscriptional regulation of methanol:coenzyme M methyltransferase isozymes in Methanosarcina acetivorans C2A.

    Opulencia, Rina B; Bose, Arpita; Metcalf, William W

    2009-11-01

    Methanosarcina species possess three operons (mtaCB1, mtaCB2, and mtaCB3) encoding methanol-specific methyltransferase 1 (MT1) isozymes and two genes (mtaA1 and mtaA2) with the potential to encode a methanol-specific methyltransferase 2 (MT2). Previous genetic studies showed that these genes are differentially regulated and encode enzymes with distinct levels of methyltransferase activity. Here, the effects of promoter strength on growth and on the rate of methane production were examined by constructing strains in which the mtaCB promoters were exchanged. When expressed from the strong PmtaC1 or PmtaC2 promoter, each of the MtaC and MtaB proteins supported growth and methane production at wild-type levels. In contrast, all mtaCB operons exhibited poorer growth and lower rates of methane production when PmtaC3 controlled their expression. Thus, previously observed phenotypic differences can be attributed largely to differences in promoter activity. Strains carrying various combinations of mtaC, mtaB, and mtaA expressed from the strong, tetracycline-regulated PmcrB(tetO1) promoter exhibited similar growth characteristics on methanol, showing that all combinations of MtaC, MtaB, and MtaA can form functional MT1/MT2 complexes. However, an in vitro assay of coupled MT1/MT2 activity showed significant variation between the strains. Surprisingly, these variations in activity correlated with differences in protein abundance, despite the fact that all the encoding genes were expressed from the same promoter. Quantitative reverse transcriptase PCR and reporter gene fusion data suggest that the mtaCBA transcripts show different stabilities, which are strongly influenced by the growth substrate. PMID:19767431

  5. Methanosarcina acetivorans 16S rRNA and transcription factor nucleotide fluctuation with implications in exobiology and pathology

    Holden, Todd; Tremberger, G., Jr.; Cheung, E.; Subramaniam, R.; Sullivan, R.; Schneider, P.; Flamholz, A.; Marchese, P.; Hiciano, O.; Yao, H.; Lieberman, D.; Cheung, T.

    2008-08-01

    Cultures of the methane-producing archaea Methanosarcina, have recently been isolated from Alaskan sediments. It has been proposed that methanogens are strong candidates for exobiological life in extreme conditions. The spatial environmental gradients, such as those associated with the polygons on Mars' surface, could have been produced by past methanogenesis activity. The 16S rRNA gene has been used routinely to classify phenotypes. Using the fractal dimension of nucleotide fluctuation, a comparative study of the 16S rRNA nucleotide fluctuation in Methanosarcina acetivorans C2A, Deinococcus radiodurans, and E. coli was conducted. The results suggest that Methanosarcina acetivorans has the lowest fractal dimension, consistent with its ancestral position in evolution. Variation in fluctuation complexity was also detected in the transcription factors. The transcription factor B (TFB) was found to have a higher fractal dimension as compared to transcription factor E (TFE), consistent with the fact that a single TFB in Methanosarcina acetivorans can code three different TATA box proteins. The average nucleotide pair-wise free energy of the DNA repair genes was found to be highest for Methanosarcina acetivorans, suggesting a relatively weak bonding, which is consistent with its low prevalence in pathology. Multitasking capacity comparison of type-I and type-II topoisomerases has been shown to correlate with fractal dimension using the methicillin-resistant strain MRSA 252. The analysis suggests that gene adaptation in a changing chemical environment can be measured in terms of bioinformatics. Given that the radiation resistant Deinococcus radiodurans is a strong candidate for an extraterrestrial origin and that the cold temperature Psychrobacter cryohalolentis K5 can function in Siberian permafrost, the fractal dimension comparison in this study suggests that a chemical resistant methanogen could exist in extremely cold conditions (such as that which existed on early

  6. Reductive nitrosylation of Methanosarcina acetivorans protoglobin: A comparative study

    Ascenzi, Paolo, E-mail: ascenzi@uniroma3.it [Laboratorio Interdipartimentale di Microscopia Elettronica, Università Roma Tre, Via della Vasca Navale 79, I-00146 Roma (Italy); Istituto di Biochimica delle Proteine, CNR, Via Pietro Castellino 111, I-80131 Napoli (Italy); Pesce, Alessandra [Dipartimento di Fisica, Università di Genova, I-16146 Genova (Italy); Nardini, Marco; Bolognesi, Martino [Dipartimento di Bioscienze, Università di Milano, Via Celoria 26, I-20133 Milano (Italy); Ciaccio, Chiara; Coletta, Massimo [Dipartimento di Scienze Cliniche e Medicina Traslazionale, Università di Roma Tor Vergata, Via Montpellier 1, I-00133 Roma (Italy); Consorzio Interuniversitario di Ricerca in Chimica dei Metalli nei Sistemi Biologici, Piazza Umberto I 1, I-70121 Bari (Italy); Dewilde, Sylvia [Department of Biomedical Sciences, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp (Belgium)

    2013-01-25

    Highlights: ► Methanosarcina acetivorans is a strictly anaerobic non-motile methane-producing Archaea. ► M. acetivorans protoglobin binds preferentially O{sub 2} rather than CO. ► Reductive nitrosylation of ferric M. acetivorans protoglobin. ► Nitrosylation of ferrious M. acetivorans protoglobin. ► M. acetivorans protoglobin is a scavenger of RNS and ROS. -- Abstract: Methanosarcina acetivorans is a strictly anaerobic non-motile methane-producing Archaea expressing protoglobin (Pgb) which might either facilitate O{sub 2} detoxification or act as a CO sensor/supplier in methanogenesis. Unusually, M. acetivorans Pgb (MaPgb) binds preferentially O{sub 2} rather than CO and displays anticooperativity in ligand binding. Here, kinetics and/or thermodynamics of ferric and ferrous MaPgb (MaPgb(III) and MaPgb(II), respectively) nitrosylation are reported. Data were obtained between pH 7.2 and 9.5, at 22.0 °C. Addition of NO to MaPgb(III) leads to the transient formation of MaPgb(III)–NO in equilibrium with MaPgb(II)–NO{sup +}. In turn, MaPgb(II)–NO{sup +} is converted to MaPgb(II) by OH{sup −}-based catalysis. Then, MaPgb(II) binds NO very rapidly leading to MaPgb(II)–NO. The rate-limiting step for reductive nitrosylation of MaPgb(III) is represented by the OH{sup −}-mediated reduction of MaPgb(II)–NO{sup +} to MaPgb(II). Present results highlight the potential role of MaPgb in scavenging of reactive nitrogen and oxygen species.

  7. Reductive nitrosylation of Methanosarcina acetivorans protoglobin: A comparative study

    Highlights: ► Methanosarcina acetivorans is a strictly anaerobic non-motile methane-producing Archaea. ► M. acetivorans protoglobin binds preferentially O2 rather than CO. ► Reductive nitrosylation of ferric M. acetivorans protoglobin. ► Nitrosylation of ferrious M. acetivorans protoglobin. ► M. acetivorans protoglobin is a scavenger of RNS and ROS. -- Abstract: Methanosarcina acetivorans is a strictly anaerobic non-motile methane-producing Archaea expressing protoglobin (Pgb) which might either facilitate O2 detoxification or act as a CO sensor/supplier in methanogenesis. Unusually, M. acetivorans Pgb (MaPgb) binds preferentially O2 rather than CO and displays anticooperativity in ligand binding. Here, kinetics and/or thermodynamics of ferric and ferrous MaPgb (MaPgb(III) and MaPgb(II), respectively) nitrosylation are reported. Data were obtained between pH 7.2 and 9.5, at 22.0 °C. Addition of NO to MaPgb(III) leads to the transient formation of MaPgb(III)–NO in equilibrium with MaPgb(II)–NO+. In turn, MaPgb(II)–NO+ is converted to MaPgb(II) by OH−-based catalysis. Then, MaPgb(II) binds NO very rapidly leading to MaPgb(II)–NO. The rate-limiting step for reductive nitrosylation of MaPgb(III) is represented by the OH−-mediated reduction of MaPgb(II)–NO+ to MaPgb(II). Present results highlight the potential role of MaPgb in scavenging of reactive nitrogen and oxygen species

  8. Metabolic reconstruction of the archaeon methanogen Methanosarcina Acetivorans

    Maranas Costas D

    2011-02-01

    Full Text Available Abstract Background Methanogens are ancient organisms that are key players in the carbon cycle accounting for about one billion tones of biological methane produced annually. Methanosarcina acetivorans, with a genome size of ~5.7 mb, is the largest sequenced archaeon methanogen and unique amongst the methanogens in its biochemical characteristics. By following a systematic workflow we reconstruct a genome-scale metabolic model for M. acetivorans. This process relies on previously developed computational tools developed in our group to correct growth prediction inconsistencies with in vivo data sets and rectify topological inconsistencies in the model. Results The generated model iVS941 accounts for 941 genes, 705 reactions and 708 metabolites. The model achieves 93.3% prediction agreement with in vivo growth data across different substrates and multiple gene deletions. The model also correctly recapitulates metabolic pathway usage patterns of M. acetivorans such as the indispensability of flux through methanogenesis for growth on acetate and methanol and the unique biochemical characteristics under growth on carbon monoxide. Conclusions Based on the size of the genome-scale metabolic reconstruction and extent of validated predictions this model represents the most comprehensive up-to-date effort to catalogue methanogenic metabolism. The reconstructed model is available in spreadsheet and SBML formats to enable dissemination.

  9. Physiology and Posttranscriptional Regulation of Methanol:Coenzyme M Methyltransferase Isozymes in Methanosarcina acetivorans C2A ▿ §

    Opulencia, Rina B.; Bose, Arpita; Metcalf, William W.

    2009-01-01

    Methanosarcina species possess three operons (mtaCB1, mtaCB2, and mtaCB3) encoding methanol-specific methyltransferase 1 (MT1) isozymes and two genes (mtaA1 and mtaA2) with the potential to encode a methanol-specific methyltransferase 2 (MT2). Previous genetic studies showed that these genes are differentially regulated and encode enzymes with distinct levels of methyltransferase activity. Here, the effects of promoter strength on growth and on the rate of methane production were examined by ...

  10. Assessing methanotrophy and carbon fixation for biofuel production by Methanosarcina acetivorans

    Nazem-Bokaee, Hadi; Gopalakrishnan, Saratram; James G. Ferry; Thomas K. Wood; Maranas, Costas D.

    2016-01-01

    Background Methanosarcina acetivorans is a model archaeon with renewed interest due to its unique reversible methane production pathways. However, the mechanism and relevant pathways implicated in (co)utilizing novel carbon substrates in this organism are still not fully understood. This paper provides a comprehensive inventory of thermodynamically feasible routes for anaerobic methane oxidation, co-reactant utilization, and maximum carbon yields of major biofuel candidates by M. acetivorans....

  11. Electron transport in acetate-grown Methanosarcina acetivorans

    Ferry James G

    2011-07-01

    Full Text Available Abstract Background Acetate is the major source of methane in nature. The majority of investigations have focused on acetotrophic methanogens for which energy-conserving electron transport is dependent on the production and consumption of H2 as an intermediate, although the great majority of acetotrophs are unable to metabolize H2. The presence of cytochrome c and a complex (Ma-Rnf homologous to the Rnf (Rhodobacter nitrogen fixation complexes distributed in the domain Bacteria distinguishes non-H2-utilizing Methanosarcina acetivorans from H2-utilizing species suggesting fundamentally different electron transport pathways. Thus, the membrane-bound electron transport chain of acetate-grown M. acetivorans was investigated to advance a more complete understanding of acetotrophic methanogens. Results A component of the CO dehydrogenase/acetyl-CoA synthase (CdhAE was partially purified and shown to reduce a ferredoxin purified using an assay coupling reduction of the ferredoxin to oxidation of CdhAE. Mass spectrometry analysis of the ferredoxin identified the encoding gene among annotations for nine ferredoxins encoded in the genome. Reduction of purified membranes from acetate-grown cells with ferredoxin lead to reduction of membrane-associated multi-heme cytochrome c that was re-oxidized by the addition of either the heterodisulfide of coenzyme M and coenzyme B (CoM-S-S-CoB or 2-hydoxyphenazine, the soluble analog of methanophenazine (MP. Reduced 2-hydoxyphenazine was re-oxidized by membranes that was dependent on addition of CoM-S-S-CoB. A genomic analysis of Methanosarcina thermophila, a non-H2-utilizing acetotrophic methanogen, identified genes homologous to cytochrome c and the Ma-Rnf complex of M. acetivorans. Conclusions The results support roles for ferredoxin, cytochrome c and MP in the energy-conserving electron transport pathway of non-H2-utilizing acetotrophic methanogens. This is the first report of involvement of a cytochrome c in

  12. Activation of Methanogenesis by Cadmium in the Marine Archaeon Methanosarcina acetivorans

    Elizabeth Lira-Silva; M Geovanni Santiago-Martínez; Viridiana Hernández-Juárez; Rodolfo García-Contreras; Rafael Moreno-Sánchez; Ricardo Jasso-Chávez

    2012-01-01

    Methanosarcina acetivorans was cultured in the presence of CdCl(2) to determine the metal effect on cell growth and biogas production. With methanol as substrate, cell growth and methane synthesis were not altered by cadmium, whereas with acetate, cadmium slightly increased both, growth and methane rate synthesis. In cultures metabolically active, incubations for short-term (minutes) with 10 µM total cadmium increased the methanogenesis rate by 6 and 9 folds in methanol- and acetate-grown cel...

  13. A phytoene desaturase homolog gene from the methanogenic archaeon Methanosarcina acetivorans is responsible for hydroxyarchaeol biosynthesis.

    Mori, Takeshi; Isobe, Keisuke; Ogawa, Takuya; Yoshimura, Tohru; Hemmi, Hisashi

    2015-10-16

    Hydroxyarchaeols are the typical core structures of archaeal membrane lipids uniquely produced by a limited number of methanogenic lineages, which are mainly classified in orders Methanosarcinales and Methanococcales. However, the biosynthetic machinery that is used for the biosynthesis of hydroxyarcheol core lipids has not been discovered. In this study, the ma0127 gene from Methanosarcina acetivorans, which encodes a phytoene desaturase-like protein, was found to be responsible for the hydration of a geranylgeranyl group in an archaeal-lipid precursor, sn-2,3-O-digeranylgeranylglyceryl phosphoglycerol, produced in Escherichia coli cells expressing several archaeal enzymes. LC-ESI-tandem-MS analyses proved that hydration occurs at the 2',3'-double bond of the geranylgeranyl group, yielding a 3'-hydroxylated lipid precursor. This result suggests that the encoded protein MA0127 is a hydratase involved in hydroxyarchaeol biosynthesis, because M. acetivorans is known to produce hydroxyarchaeol core lipids with a 3'-hydroxyphytanyl group. Furthermore, the distribution of the putative orthologs of ma0127 among methanogens is generally in good agreement with that of hydroxyarchaeol producers, including anaerobic methanotrophs (ANMEs). PMID:26361140

  14. Air-adapted Methanosarcina acetivorans shows high methane production and develops resistance against oxygen stress.

    Ricardo Jasso-Chávez

    Full Text Available Methanosarcina acetivorans, considered a strict anaerobic archaeon, was cultured in the presence of 0.4-1% O2 (atmospheric for at least 6 months to generate air-adapted cells; further, the biochemical mechanisms developed to deal with O2 were characterized. Methane production and protein content, as indicators of cell growth, did not change in air-adapted cells respect to cells cultured under anoxia (control cells. In contrast, growth and methane production significantly decreased in control cells exposed for the first time to O2. Production of reactive oxygen species was 50 times lower in air-adapted cells versus control cells, suggesting enhanced anti-oxidant mechanisms that attenuated the O2 toxicity. In this regard, (i the transcripts and activities of superoxide dismutase, catalase and peroxidase significantly increased; and (ii the thiol-molecules (cysteine + coenzyme M-SH + sulfide and polyphosphate contents were respectively 2 and 5 times higher in air-adapted cells versus anaerobic-control cells. Long-term cultures (18 days of air-adapted cells exposed to 2% O2 exhibited the ability to form biofilms. These data indicate that M. acetivorans develops multiple mechanisms to contend with O2 and the associated oxidative stress, as also suggested by genome analyses for some methanogens.

  15. Structural Bases for the Regulation of CO Binding in the Archaeal Protoglobin from Methanosarcina acetivorans.

    Lesley Tilleman

    Full Text Available Studies of CO ligand binding revealed that two protein states with different ligand affinities exist in the protoglobin from Methanosarcina acetivorans (in MaPgb*, residue Cys(E20101 was mutated to Ser. The switch between the two states occurs upon the ligation of MaPgb*. In this work, site-directed mutagenesis was used to explore the role of selected amino acids in ligand sensing and stabilization and in affecting the equilibrium between the "more reactive" and "less reactive" conformational states of MaPgb*. A combination of experimental data obtained from electronic and resonance Raman absorption spectra, CO ligand-binding kinetics, and X-ray crystallography was employed. Three amino acids were assigned a critical role: Trp(60B9, Tyr(61B10, and Phe(93E11. Trp(60B9 and Tyr(61B10 are involved in ligand stabilization in the distal heme pocket; the strength of their interaction was reflected by the spectra of the CO-ligated MaPgb* and by the CO dissociation rate constants. In contrast, Phe(93E11 is a key player in sensing the heme-bound ligand and promotes the rotation of the Trp(60B9 side chain, thus favoring ligand stabilization. Although the structural bases of the fast CO binding rate constant of MaPgb* are still unclear, Trp(60B9, Tyr(61B10, and Phe(93E11 play a role in regulating heme/ligand affinity.

  16. Activation of methanogenesis by cadmium in the marine archaeon Methanosarcina acetivorans.

    Elizabeth Lira-Silva

    Full Text Available Methanosarcina acetivorans was cultured in the presence of CdCl(2 to determine the metal effect on cell growth and biogas production. With methanol as substrate, cell growth and methane synthesis were not altered by cadmium, whereas with acetate, cadmium slightly increased both, growth and methane rate synthesis. In cultures metabolically active, incubations for short-term (minutes with 10 µM total cadmium increased the methanogenesis rate by 6 and 9 folds in methanol- and acetate-grown cells, respectively. Cobalt and zinc but not copper or iron also activated the methane production rate. Methanogenic carbonic anhydrase and acetate kinase were directly activated by cadmium. Indeed, cells cultured in 100 µM total cadmium removed 41-69% of the heavy metal from the culture and accumulated 231-539 nmol Cd/mg cell protein. This is the first report showing that (i Cd(2+ has an activating effect on methanogenesis, a biotechnological relevant process in the bio-fuels field; and (ii a methanogenic archaea is able to remove a heavy metal from aquatic environments.

  17. The Methanosarcina barkeri genome: comparative analysis withMethanosarcina acetivorans and Methanosarcina mazei reveals extensiverearrangement within methanosarcinal genomes

    Maeder, Dennis L.; Anderson, Iain; Brettin, Thomas S.; Bruce,David C.; Gilna, Paul; Han, Cliff S.; Lapidus, Alla; Metcalf, William W.; Saunders, Elizabeth; Tapia, Roxanne; Sowers, Kevin R.

    2006-05-19

    We report here a comparative analysis of the genome sequence of Methanosarcina barkeri with those of Methanosarcina acetivorans and Methanosarcina mazei. All three genomes share a conserved double origin of replication and many gene clusters. M. barkeri is distinguished by having an organization that is well conserved with respect to the other Methanosarcinae in the region proximal to the origin of replication with interspecies gene similarities as high as 95%. However it is disordered and marked by increased transposase frequency and decreased gene synteny and gene density in the proximal semi-genome. Of the 3680 open reading frames in M. barkeri, 678 had paralogs with better than 80% similarity to both M. acetivorans and M. mazei while 128 nonhypothetical orfs were unique (non-paralogous) amongst these species including a complete formate dehydrogenase operon, two genes required for N-acetylmuramic acid synthesis, a 14 gene gas vesicle cluster and a bacterial P450-specific ferredoxin reductase cluster not previously observed or characterized in this genus. A cryptic 36 kbp plasmid sequence was detected in M. barkeri that contains an orc1 gene flanked by a presumptive origin of replication consisting of 38 tandem repeats of a 143 nt motif. Three-way comparison of these genomes reveals differing mechanisms for the accrual of changes. Elongation of the large M. acetivorans is the result of multiple gene-scale insertions and duplications uniformly distributed in that genome, while M. barkeri is characterized by localized inversions associated with the loss of gene content. In contrast, the relatively short M. mazei most closely approximates the ancestral organizational state.

  18. Apo and ligand-bound structures of ModA from the archaeon Methanosarcina acetivorans.

    Chan, Sum; Giuroiu, Iulia; Chernishof, Irina; Sawaya, Michael R; Chiang, Janet; Gunsalus, Robert P; Arbing, Mark A; Perry, L Jeanne

    2010-03-01

    The trace-element oxyanion molybdate, which is required for the growth of many bacterial and archaeal species, is transported into the cell by an ATP-binding cassette (ABC) transporter superfamily uptake system called ModABC. ModABC consists of the ModA periplasmic solute-binding protein, the integral membrane-transport protein ModB and the ATP-binding and hydrolysis cassette protein ModC. In this study, X-ray crystal structures of ModA from the archaeon Methanosarcina acetivorans (MaModA) have been determined in the apoprotein conformation at 1.95 and 1.69 A resolution and in the molybdate-bound conformation at 2.25 and 2.45 A resolution. The overall domain structure of MaModA is similar to other ModA proteins in that it has a bilobal structure in which two mixed alpha/beta domains are linked by a hinge region. The apo MaModA is the first unliganded archaeal ModA structure to be determined: it exhibits a deep cleft between the two domains and confirms that upon binding ligand one domain is rotated towards the other by a hinge-bending motion, which is consistent with the 'Venus flytrap' model seen for bacterial-type periplasmic binding proteins. In contrast to the bacterial ModA structures, which have tetrahedral coordination of their metal substrates, molybdate-bound MaModA employs octahedral coordination of its substrate like other archaeal ModA proteins. PMID:20208152

  19. The nutritional status of Methanosarcina acetivorans regulates glycogen metabolism and gluconeogenesis and glycolysis fluxes.

    Santiago-Martínez, Michel Geovanni; Encalada, Rusely; Lira-Silva, Elizabeth; Pineda, Erika; Gallardo-Pérez, Juan Carlos; Reyes-García, Marco Antonio; Saavedra, Emma; Moreno-Sánchez, Rafael; Marín-Hernández, Alvaro; Jasso-Chávez, Ricardo

    2016-05-01

    Gluconeogenesis is an essential pathway in methanogens because they are unable to use exogenous hexoses as carbon source for cell growth. With the aim of understanding the regulatory mechanisms of central carbon metabolism in Methanosarcina acetivorans, the present study investigated gene expression, the activities and metabolic regulation of key enzymes, metabolite contents and fluxes of gluconeogenesis, as well as glycolysis and glycogen synthesis/degradation pathways. Cells were grown with methanol as a carbon source. Key enzymes were kinetically characterized at physiological pH/temperature. Active consumption of methanol during exponential cell growth correlated with significant methanogenesis, gluconeogenic flux and steady glycogen synthesis. After methanol exhaustion, cells reached the stationary growth phase, which correlated with the rise in glycogen consumption and glycolytic flux, decreased methanogenesis, negligible acetate production and an absence of gluconeogenesis. Elevated activities of carbon monoxide dehydrogenase/acetyl-CoA synthetase complex and pyruvate: ferredoxin oxidoreductase suggested the generation of acetyl-CoA and pyruvate for glycogen synthesis. In the early stationary growth phase, the transcript contents and activities of pyruvate phosphate dikinase, fructose 1,6-bisphosphatase and glycogen synthase decreased, whereas those of glycogen phosphorylase, ADP-phosphofructokinase and pyruvate kinase increased. Therefore, glycogen and gluconeogenic metabolites were synthesized when an external carbon source was provided. Once such a carbon source became depleted, glycolysis and methanogenesis fed by glycogen degradation provided the ATP supply. Weak inhibition of key enzymes by metabolites suggested that the pathways evaluated were mainly transcriptionally regulated. Because glycogen metabolism and glycolysis/gluconeogenesis are not present in all methanogens, the overall data suggest that glycogen storage might represent an environmental

  20. Nitrite-reductase and peroxynitrite isomerization activities of Methanosarcina acetivorans protoglobin.

    Paolo Ascenzi

    Full Text Available Within the globin superfamily, protoglobins (Pgb belong phylogenetically to the same cluster of two-domain globin-coupled sensors and single-domain sensor globins. Multiple functional roles have been postulated for Methanosarcina acetivorans Pgb (Ma-Pgb, since the detoxification of reactive nitrogen and oxygen species might co-exist with enzymatic activity(ies to facilitate the conversion of CO to methane. Here, the nitrite-reductase and peroxynitrite isomerization activities of the CysE20Ser mutant of Ma-Pgb (Ma-Pgb* are reported and analyzed in parallel with those of related heme-proteins. Kinetics of nitrite-reductase activity of ferrous Ma-Pgb* (Ma-Pgb*-Fe(II is biphasic and values of the second-order rate constant for the reduction of NO2- to NO and the concomitant formation of nitrosylated Ma-Pgb*-Fe(II (Ma-Pgb*-Fe(II-NO are k(app1= 9.6 ± 0.2 M(-1 s(-1 and k(app2 = 1.2 ± 0.1 M(-1 s(-1 (at pH 7.4 and 20 °C. The k(app1 and k(app2 values increase by about one order of magnitude for each pH unit decrease, between pH 8.3 and 6.2, indicating that the reaction requires one proton. On the other hand, kinetics of peroxynitrite isomerization catalyzed by ferric Ma-Pgb* (Ma-Pgb*-Fe(III is monophasic and values of the second order rate constant for peroxynitrite isomerization by Ma-Pgb*-Fe(III and of the first order rate constant for the spontaneous conversion of peroxynitrite to nitrate are h(app = 3.8 × 10(4 M(-1 s(-1 and h0 = 2.8 × 10(-1 s(-1 (at pH 7.4 and 20 °C. The pH-dependence of hon and h0 values reflects the acid-base equilibrium of peroxynitrite (pKa = 6.7 and 6.9, respectively; at 20 °C, indicating that HOONO is the species that reacts preferentially with the heme-Fe(III atom. These results highlight the potential role of Pgbs in the biosynthesis and scavenging of reactive nitrogen and oxygen species.

  1. Geranylgeranyl reductase and ferredoxin from Methanosarcina acetivorans are required for the synthesis of fully reduced archaeal membrane lipid in Escherichia coli cells.

    Isobe, Keisuke; Ogawa, Takuya; Hirose, Kana; Yokoi, Takeru; Yoshimura, Tohru; Hemmi, Hisashi

    2014-01-01

    Archaea produce membrane lipids that typically possess fully saturated isoprenoid hydrocarbon chains attached to the glycerol moiety via ether bonds. They are functionally similar to, but structurally and biosynthetically distinct from, the fatty acid-based membrane lipids of bacteria and eukaryotes. It is believed that the characteristic lipid structure helps archaea survive under severe conditions such as extremely low or high pH, high salt concentrations, and/or high temperatures. We detail here the first successful production of an intact archaeal membrane lipid, which has fully saturated isoprenoid chains, in bacterial cells. The introduction of six phospholipid biosynthetic genes from a methanogenic archaeon, Methanosarcina acetivorans, in Escherichia coli enabled the host bacterium to synthesize the archaeal lipid, i.e., diphytanylglyceryl phosphoglycerol, while a glycerol modification of the phosphate group was probably catalyzed by endogenous E. coli enzymes. Reduction of the isoprenoid chains occurred only when archaeal ferredoxin was expressed with geranylgeranyl reductase, suggesting the role of ferredoxin as a specific electron donor for the reductase. This report is the first identification of a physiological reducer for archaeal geranylgeranyl reductase. On the other hand, geranylgeranyl reductase from the thermoacidophilic archaeon Sulfolobus acidocaldarius could, by itself, replace both its orthologue and ferredoxin from M. acetivorans, which indicated that an endogenous redox system of E. coli reduced the enzyme. PMID:24214941

  2. Mechanism for Calcium Ion Sensing by the C2A Domain of Synaptotagmin I

    Gauer, Jacob W.; Sisk, Ryan; Murphy, Jesse R.; Jacobson, Heathere; Sutton, R. Bryan; Gillispie, Gregory D.; Hinderliter, Anne

    2012-01-01

    The C2A domain is one of two calcium ion (Ca2+)- and membrane-binding domains within synaptotagmin I (Syt I), the identified Ca2+ sensor for regulated exocytosis of neurotransmitter. We propose that the mechanistic basis for C2A's response to Ca2+ and cellular function stems from marginal stability and ligand-induced redistributions of protein conformers. To test this hypothesis, we used a combination of calorimetric and fluorescence techniques. We measured free energies of stability by globa...

  3. 26 CFR 31.6302(c)-2A - Use of Government depositaries in connection with the railroad unemployment repayment tax.

    2010-04-01

    ... with the railroad unemployment repayment tax. 31.6302(c)-2A Section 31.6302(c)-2A Internal Revenue...) § 31.6302(c)-2A Use of Government depositaries in connection with the railroad unemployment repayment...,000,000, such employer shall (except as provided below) deposit his undeposited railroad...

  4. The C2A domain in dysferlin is important for association with MG53 (TRIM72)

    Matsuda, Chie; Miyake, Katsuya; Kameyama, Kimihiko; Keduka, Etsuko; Takeshima, Hiroshi; Imamura, Toru; Araki, Nobukazu; NISHINO, Ichizo; Hayashi, Yukiko

    2012-01-01

    In skeletal muscle, Mitsugumin 53 (MG53), also known as muscle-specific tripartite motif 72, reportedly interacts with dysferlin to regulate membrane repair. To better understand the interactions between dysferlin and MG53, we conducted immunoprecipitation (IP) and pull-down assays. Based on IP assays, the C2A domain in dysferlin associated with MG53. MG53 reportedly exists as a monomer, a homodimer, or an oligomer, depending on the redox state. Based on pull-down assays, wild-type dysferlin ...

  5. Noninvasive detection of experimental acute venous thrombosis with 99Tcm labeled C2A domain of synaptotagmin I

    99Tcm labeled C2A domain of synaptotagmin I(99Tcm-Syt I-C2A) is a scintigraphic tracer that binds to phosphatidylserine exposed on activated platelets. This study is to determine the potential of this agent for imaging acute venous thrombosis. A stainless steel was placed in femoral vein for inducing venous thrombi in 5 dogs, which were injected each with 185 MBq of 99Tcm-Syt I-C2A. Images of legs were acquired at 1, 2 and 3 h after injection. ROI analysis was applied to measure the thrombus-to-contralateral location and thrombus-to-background ratios. The samples of thrombus, blood, and muscle were separated and were counted in a γ well counter for percent injected dose %ID·g-1. Thrombus-to-blood and thrombus-to-muscle ratios were calculated from the %ID·g-1 value. In in vivo imaging, the thrombus-to-contralateral location ratios were 3.01±0.30, 3.22±0.21 and 3.37±0.57, respectively, and thrombus-to-background ratios were 3.10±0.39, 3.32±0.31 and 3.50±0.45, respectively, at 1, 2 and 3 h after injection. The thrombus-to-blood and thrombus-to-muscle ratios of %ID·g-1 were 2.40±0.35 and 68.90±45.30, respectively. 99Tcm-Syt I-C2A with high venous thrombus uptake is a promising agent for imaging acute venous thrombosis. (authors)

  6. Purification, crystallization and X-ray diffraction analysis of human synaptotagmin 1 C2A-C2B

    Human synaptotagmin C2A-C2B has been expressed as a glutathione-S-transferase fusion protein in Escherichia coli. The purification, crystallization and preliminary X-ray analysis of this protein are reported here. Synaptotagmin acts as the Ca2+ sensor for neuronal exocytosis. The cytosolic domain of human synaptotagmin 1 is composed of tandem C2 domains: C2A and C2B. These C2 domains modulate the interaction of synaptotagmin with the phospholipid bilayer of the presynaptic terminus and effector proteins such as the SNARE complex. Human synaptotagmin C2A-C2B has been expressed as a glutathione-S-transferase fusion protein in Escherichia coli. The purification, crystallization and preliminary X-ray analysis of this protein are reported here. The crystals diffract to 2.7 Å and belong to the orthorhombic space group P212121, with unit-cell parameters a = 82.37, b = 86.31, c = 140.2 Å. From self-rotation function analysis, there are two molecules in the asymmetric unit. The structure determination of the protein using this data is ongoing

  7. Quantitative analysis of [99mTc]C2A-GST distribution in the area at risk after myocardial ischemia and reperfusion using a compartmental model

    Objective: It was recently demonstrated that the radiolabeled C2A domain of synaptotagmin I accumulates avidly in the area at risk after ischemia and reperfusion. The objective was to quantitatively characterize the dynamic uptake of radiolabeled C2A in normal and ischemically injured myocardia using a compartmental model. Methods: To induce acute myocardial infarction, the left descending coronary artery was ligated for 18 min, followed by reperfusion. [99mTc]C2A-GST or its inactivated form, [99mTc]C2A-GST-NHS, was injected intravenously at 2 h after reperfusion. A group of four rats was sacrificed at 10, 30, 60 and 180 after injection. Uptake of [99mTc]C2A-GST and [99mTc]C2A-GST-NHS in the area at risk and in the normal myocardium were determined by gamma counting. A compartmental model was developed to quantitatively interpret myocardial uptake kinetic data. The model consists of two physical spaces (vascular space and tissue space), with plasma activity as input. The model allows for [99mTc]C2A-GST and [99mTc]C2A-GST-NHS diffusion between vascular and tissue spaces, as well as for [99mTc]C2A-GST sequestration in vascular and tissue spaces via specific binding. Results: [99mTc]C2A-GST uptake in the area at risk was significantly higher than that for [99mTc]C2A-GST-NHS at all time points. The compartmental model separated [99mTc]C2A-GST uptake in the area at risk due to passive retention from that due to specific binding. The maximum amount of [99mTc]C2A-GST that could be sequestered in the area at risk due to specific binding was estimated at a total of 0.048 nmol/g tissue. The rate of [99mTc]C2A-GST sequestration within the tissue space of the area at risk was 0.012 ml/min. Modeling results also revealed that the diffusion rate of radiotracer between vascular and tissue spaces is the limiting factor of [99mTc]C2A-GST sequestration within the tissue space of the area at risk. Conclusion: [99mTc]C2A-GST is sequestered in the ischemically injured myocardium in a

  8. Expression of C2A domain of synaptotagmin I fusion protein and its imaging in the ischemia-reperfusion rat model

    Objective: To evaluate myocardial apoptosis with 99Tcm-C2A-GST myocardial imaging using the recombined C2A domain of Synaptotagmin I by gene engineering. Methods: (1) The C2A gene was inserted into the prokaryotic glutathione S-transferate (GST) fusion protein expression plasmid pGEX-6P-1. The recombinant plasmid was transformed into E. coli BL21. C2A-GST fusion protein was purified after BL21 was induced with isopropyl-β-D-1-thiogalactopyranoside (IPTG). (2) The activity of fusion protein was identified by cell binding test with fluorescein-5-isothiocyanate (FITC)-C2A-GST. (3) The C2A-GST fusion protein was labeled with 99Tcm using 2-iminothiophene hydrocoride method. Radiochemical purity was determined with thin layer chromatography. (4) 99Tcm-C2A-GST (7.4 MBq) was injected to ischemia-reperfusion rat models through tail vein. The image was acquired with SPECT at 1 h after injection, and then hearts were removed, rinsed with saline and dyed with triphenyl tetrazolium coride (TTC). The ischemic myocardium was separated from the viable myocardium and was weighted. Its radioactivity was measured by gamma counting. The difference of uptake of radiotracer between ischemic myocardium and normal myocardium was compared using percentage activity of injected dose per gram of tissue (% ID/g) with standard deviation. SPSS 12.0 and t-test were used for data analysis. Results: (1) C2A-GST fusion protein was successfully expressed and its relative molecular weight was 3.8 x 104. (2) FITC-C2A-GST binding to apoptotic cells could be observed by fluorescent microscopy. (3) The radiochemical purity of 99Tcm-C2A-GST was (98.90 ±0.43)%. (4) The imaging studies showed that there was focal uptake of radioactivity in the ischemic myocardium. In vitro uptake of 99Tcm-C2A-GST was (2.41±0.32) % ID/g by the ischemic myocardium, however 99Tcm-C2A-GST-N-hydroxysuccinimide (C2A-GST-NHS) was (0.82±0.24) % ID/g. There was statistically significant difference between those two groups (t=10

  9. Cloning, expression, purification, crystallization and preliminary X-ray diffraction crystallographic study of human synaptotagmin 5 C2A domain

    This paper reports the cloning, expression, purification, crystallization and preliminary X-ray crystallographic analysis of the first C2 domain of synaptotagmin 5. Synaptotagmin acts as the Ca2+ sensor for neural and endocrine exocytosis. Synaptotagmin 5 has been demonstrated to play a key role in the acquisition of cathepsin D and the vesicular proton ATPase and in Ca2+-dependent insulin exocytosis. The C2 domains modulate the interaction of synaptotagmin with the phospholipid bilayer of the presynaptic terminus and effector proteins such as the SNARE complex. This study reports the cloning, expression in Escherichia coli, purification, crystallization and preliminary X-ray analysis of the C2A domain of human synaptotagmin 5 with an N-terminal His6 tag. The crystals diffracted to 1.90 Å resolution and belonged to the hexagonal space group P65, with unit-cell parameters a = b = 93.97, c = 28.05 Å. A preliminary model of the protein structure has been built and refinement of the model is ongoing

  10. SPECT imaging of myocardial infarction using {sup 99m}Tc-labeled C2A domain of synaptotagmin I in a porcine ischemia-reperfusion model

    Fang Wei [Department of Nuclear Medicine, Cardiovascular Institute and Fu Wai Hospital, Chinese Academy of Medical Sciences, Beijing 100037 (China); Wang Feng [Nuclear Medicine Department, Nanjing First Hospital Affiliated to Nanjing Medical University, Nanjing 210006 (China); Ji Shundong [Jiangsu Institute of Hematology, 1st Hospital of Suzhou University, Suzhou 215006 (China); Zhu Xiaoguang [Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin, WI 53226 (United States); Meier, Heidi T. [Clinical Veterinarian and Radiology Research, Clement J. Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin, WI 53295 (United States); Hellman, Robert S. [Department of Radiology, Medical College of Wisconsin, Milwaukee, Wisconsin, WI 53226 (United States); Brindle, Kevin M. [MRC Laboratory of Molecular Biology, Cambridge CB2 2QH (United Kingdom); Davletov, Bazbek [Department of Biochemistry, University of Cambridge, Cambridge CB2 1GA (United Kingdom); Zhao Ming [Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin, WI 53226 (United States)], E-mail: mzhao@mcw.edu

    2007-11-15

    Introduction: The C2A domain of synaptotagmin I recognizes necrotic and apoptotic cells by binding to exposed anionic phospholipids. The goal is to explore the potential imaging utility of {sup 99m}Tc-labeled C2A in the detection of acute cardiac cell death in a porcine model that resembles human cardiovascular physiology. Methods: Ischemia (20-25 min) was induced in pigs (M/F, 20-25 kg) using balloon angioplasty. {sup 99m}Tc-C2A-GST (n=7) or {sup 99m}Tc-BSA (n=2) was injected intravenously 1-2 h after reperfusion. Noninfarct animals were injected with {sup 99m}Tc-C2A-GST (n=4). SPECT images were acquired at 3 and 6 h postinjection. Cardiac tissues were analyzed to confirm the presence of cell death. Results: Focal uptake was detected in five out of seven subjects at 3 h and in all infarct subjects at 6 h postinjection but not in infarct animals injected with {sup 99m}Tc-BSA or in noninfarct animals with {sup 99m}Tc-C2A-GST. Gamma counting of infarct versus normal myocardium yielded a 10.2{+-}5.7-fold elevation in absolute radioactivity, with histologically confirmed infarction. Conclusions: We present data on imaging myocardial cell death in the acute phase of infarction in pigs. C2A holds promise and warrants further development as an infarct-avid molecular probe.

  11. Transfer of Methanolobus siciliae to the genus Methanosarcina, naming it Methanosarcina siciliae, and emendation of the genus Methanosarcina

    Ni, S.; Woese, C. R.; Aldrich, H. C.; Boone, D. R.

    1994-01-01

    A sequence analysis of the 16S rRNA of Methanolobus siciliae T4/M(T) (T = type strain) showed that this strain is closely related to members of the genus Methanosarcina, especially Methanosarcina acetivorans C2A(T). Methanolobus siciliae T4/M(T) and HI350 were morphologically more similar to members of the genus Methanosarcina than to members of the genus Methanolobus in that they both formed massive cell aggregates with pseudosarcinae. Thus, we propose that Methanolobus siciliae should be transferred to the genus Methanosarcina as Methanosarcina siciliae.

  12. Two forms of the membrane-bound state of the first C2 domain (C2A) of synaptotagminⅠand calcium-triggered membrane insertion

    HE Yuhong; LI Xianghui; WANG Fu; XUE Yi; SUI Senfang

    2003-01-01

    The synaptic vesicle protein synaptotagminⅠ (sytⅠ) is a vesicle trans membrane protein present in synaptic vesicles, which has been proposed as the Ca 2+ sensor that regulates secretion. The C2A domain is the membrane proximal part of its cytoplasmic domain. The interaction between C2A and lipid bilayer has be en considered to be essential for triggering neurotransmitter release. In the pr esent work, the measurements of membrane surface tension and surface concentrati on showed that the C2A domain of sytⅠexhibited two membrane-bound states: the s urface adsorption state and the membrane insertion state. The surface absorption state formed in a Ca2+-independent manner with lower affinity, while the membra ne insertion state formed with high affinity was only found in the presence of C a2+. Both the Ca2+-independent and Ca2+-dependent sytⅠ- membrane interactions r equired anionic phospholipids, such as phosphatidylserine (PS). When expressed i nto rat pheochromocytoma (PC12) cells and human embryonic kidney (HEK-293) cells , as demonstrated by immunofluorescence staining and subcellular fractionation, most of the C2A was found at the plasma membrane, even when the cells were deple ted of Ca2+ by incubation with EGTA. These results suggested a new molecular mec hanism of sytⅠas a Ca2+ sensor in membrane fusion. Ca2+-independent surface ads orption might attach sytⅠto the release site during the docking or priming step . When intracellular Ca2+ increased, sytⅠtriggered the neurotransmitter release following the Ca2+-dependent penetration into the target membrane.

  13. Evaluation of cardioprotective effect of ischemic preconditioning on ischemic myocardium using 99Tcm-Syt I-C2A in the myocardial ischemia-reperfusion rat model

    Objective: Precondition is an approach to myocardial protection during ischemia-reperfusion by inhibiting myocardial cell apoptosis. The purpose of this study was to evaluate the cardioprotective effect using 99Tcm-synaptotagmin I (Syt I) -C2A to detect myocardial cell apoptosis in the myocardial is-chemia-reperfusion rat model. Methods: (1) The C2A domain of Syt I was labeled with 99Tcm using 2-iminothiophene hydrochloride (IT) method. Radiochemical purity was determined with thin layer chroma-tography. The binding activity of radiolabeled protein was assessed using camptothecin-treated Jurket cells. (2) One group of 6 rats was prepared for myocardial ischemia-reperfusion model (A group), and another group of 6 rats was prepared for myocardial ischemia precondition model (B group). 99Tcm-Syt I-C2A was injected via the tail vein at a dosage of about 7.4 MBq. At 1h after injection, the rat was sacrificed, and the heart was removed to rinse with saline and dye with triphenyl tetrazolium coride (TTC). According to the resdt of myocardial dye, theischemic myocardium was separated from the viable myocardium and weight was measured, and then its radioactivity was determined by gamma counting. The difference of radioactive uptake in the ischemic myocardium between these two group models was compared using percentage activity of injection dose per gram of tissue (%ID/g) ± standard deviation [(x -bar)± s]. SPSS 12.0 was used for data analysis, and t-test was used to compare data. Results: (1) The radiochemical purity of 99Tcm-Syt I-C2A was (98.90 ± 0.43)%, and the radioactivity in the camptothecin-treated group was (10.99 ± 0.55) folds higher than that of non-treated viable control group. (2)In the ischemia-reperfusion model, the radioactive uptake of 99Tcm-Syt, I-C2A was (2.41 ± 0.32)% ID/g in the ischemic myocardium, and (0.16 ± O.02)% ID/g in the nomud myocardiunm. However, in the myocardial ischemia precondition model, (0.46 ± 0.05)% ID/g in the ischemic

  14. Copper-64 radiolabelling of the C2A domain of synaptotagmin I using a functionalised bis(thiosemicarbazone): A pre- and post-labelling comparison.

    Hueting, Rebekka; Tavaré, Richard; Dilworth, Jonathan R; Mullen, Gregory E

    2013-11-01

    Dysregulation of apoptosis and necrosis is central to many diseases and non-invasive imaging of cell death is an important clinical objective to stage disease or to monitor treatment progress. The C2A domain of rat synaptotagmin I binds to phosphatidylserine (PS) exposed during cell death and modification to its lysine residues has been shown to disrupt PS binding. Site-specifically labelled (99m)Tc(CO)3-C2AcH and (68)Ga-C2Ac have previously been investigated for single photon emission computed tomography (SPECT) and positron emission tomography (PET) imaging, respectively. We wished to design a (64)Cu-labelled counterpart due to the longer half-life of (64)Cu. Since the calcium binding sites in C2A may interfere with copper binding we sought a high affinity, fast labelling chelator. We synthesised a maleimide functionalised bis(thiosemicarbazone), H2ATSE/AMal, for the site-specific copper-64 radiolabelling of thiol-functionalised C2Ac. When radiolabelling was performed by incubation of the ligand-protein conjugate (post-labelling approach), analysis of the resultant (64)CuATSE/AMal-C2Ac revealed that the C2Ac was able to compete for radiocopper with the chelator. In contrast, the pre-labelled (64)CuATSE/AMal-C2Ac conjugate revealed good stability in serum and maintained target affinity in a red blood cell binding assay. The results suggest that due to the intrinsic copper binding properties of the protein, a pre-labelling approach is preferred for the C2Ac domain of synaptotagmin I when copper is the desired radioisotope. PMID:23954480

  15. S100A13-C2A binary complex structure-a key component in the acidic fibroblast growth factor for the non-classical pathway

    , we have studied the interactions of S100A13 with C2A by 1H-15N HSQC titration and 3D-filtered NOESY experiments. We characterized the binary complex structure of S100A13-C2A by using a variety of multi-dimensional NMR experiments. This complex acts as a template for FGF-1 dimerization and multiprotein complex formation.

  16. In vivo dynamic imaging of myocardial cell death using 99mTc-labeled C2A domain of Synaptotagmin I in a rat model of ischemia and reperfusion

    Liu, Zhonglin; Zhao, Ming; Zhu, Xiaoguang; Furenlid, Lars R.; Chen, Yi-Chun; Barrett, Harrison H.

    2007-01-01

    This study was designed to investigate the capability of a small-animal SPECT imager, FastSPECT II, for dynamic rat heart imaging and to characterize the in vivo kinetic properties of 99mTc-C2A-GST, a molecular probe targeting apoptosis and necrosis, in detecting cell death in ischemic-reperfused rat hearts.

  17. Geobacteraceae strains and methods

    Lovley, Derek R.; Nevin, Kelly P.; Yi, Hana

    2015-07-07

    Embodiments of the present invention provide a method of producing genetically modified strains of electricigenic microbes that are specifically adapted for the production of electrical current in microbial fuel cells, as well as strains produced by such methods and fuel cells using such strains. In preferred embodiments, the present invention provides genetically modified strains of Geobacter sulfurreducens and methods of using such strains.

  18. In vivo dynamic imaging of myocardial cell death using 99mTc-labeled C2A domain of synaptotagmin I in a rat model of ischemia and reperfusion

    Objectives: This study was designed to investigate the capability of a small-animal SPECT imager, FastSPECT II, for dynamic rat heart imaging and to characterize the in vivo kinetic properties of 99mTc-C2A-glutathione-s-transferase (GST), a molecular probe targeting apoptosis and necrosis, in detecting cell death in ischemic-reperfused rat hearts. Methods: C2A-GST was radiolabeled with 99mTc via 2-iminothiolane thiolation. Myocardial ischemia-reperfusion was induced by 30-min ligation of the left coronary artery followed by 120-min reperfusion in seven rats. FastSPECT II cardiac images of 99mTc-C2A-GST in list-mode acquisition were recorded for 2 h using FastSPECT II. Results: Tomographic images showed a focal radioactive accumulation (hot spot) in the lateral and anterior walls of the left ventricle. The hot spot was initially visualized 10 min after injection and persisted on the 2-h images. Quantitative analysis demonstrated that the hot-spot radioactivity increased significantly within 30 min postinjection and experienced no washout up to the end of the 2-h study. The ratio of the hot spot/viable myocardium was 4.52±0.24, and infarct-to-lung ratio was 8.22±0.63 at 2 h postinjection. The uptake of 99mTc-C2A-GST in the infarcted myocardium was confirmed by triphenyl tetrazolium chloride staining and autoradiography analysis. Conclusions: FastSPECT II allows quantitative dynamic imaging and functional determination of radiotracer kinetics in rat hearts. An in vivo kinetic profile of 99mTc-C2A-GST in the ischemic-reperfused rat heart model was characterized successfully. The pattern of accelerated 99mTc-C2A-GST uptake in the ischemic area at risk after reperfusion may be useful in detecting and quantifying ongoing myocardial cell loss induced by ischemia-reperfusion

  19. Muscle strain (image)

    A muscle strain is the stretching or tearing of muscle fibers. A muscle strain can be caused by sports, exercise, a ... something that is too heavy. Symptoms of a muscle strain include pain, tightness, swelling, tenderness, and the ...

  20. Muscle strain treatment

    Treatment - muscle strain ... Question: How do you treat a muscle strain ? Answer: Rest the strained muscle and apply ice for the first few days after the injury. Anti-inflammatory medicines or acetaminophen ( ...

  1. Program Calibrates Strain Gauges

    Okazaki, Gary D.

    1991-01-01

    Program dramatically reduces personnel and time requirements for acceptance tests of hardware. Data-acquisition system reads output from Wheatstone full-bridge strain-gauge circuit and calculates strain by use of shunt calibration technique. Program nearly instantaneously tabulates and plots strain data against load-cell outputs. Modified to acquire strain data for other specimens wherever full-bridge strain-gauge circuits used. Written in HP BASIC.

  2. Strains and Sprains

    ... ON THIS TOPIC Sports Medicine Center Preventing Children's Sports Injuries Computer-Related Repetitive Stress Injuries Knee Injuries Broken ... Knee Injuries Sports and Exercise Safety Dealing With Sports Injuries Groin Strain Ankle Sprains Strains and Sprains Stretching ...

  3. Strained Silicon Photonics

    Wehrspohn, Ralf B; Jörg Schilling; Christian Bohley; Clemens Schriever

    2012-01-01

    A review of recent progress in the field of strained silicon photonics is presented. The application of strain to waveguide and photonic crystal structures can be used to alter the linear and nonlinear optical properties of these devices. Here, methods for the fabrication of strained devices are summarized and recent examples of linear and nonlinear optical devices are discussed. Furthermore, the relation between strain and the enhancement of the second order nonlinear susceptibility is inves...

  4. Diffraction tomography of strain

    Lionheart, W R B; Withers, P. J.

    2015-01-01

    We consider whether it is possible to recover the three dimensional strain field tomographically from neutron and x-ray diffraction data for polycrystalline materials. We show that the distribution of strain transverse to a ray cannot be deduced from one diffraction pattern accumulated along that path, but that a certain moment of that data corresponds to the transverse ray transform of the strain tensor and so may be recovered by inverting that transform given sufficient data. We show that t...

  5. Strained Silicon Photonics

    Ralf B. Wehrspohn

    2012-05-01

    Full Text Available A review of recent progress in the field of strained silicon photonics is presented. The application of strain to waveguide and photonic crystal structures can be used to alter the linear and nonlinear optical properties of these devices. Here, methods for the fabrication of strained devices are summarized and recent examples of linear and nonlinear optical devices are discussed. Furthermore, the relation between strain and the enhancement of the second order nonlinear susceptibility is investigated, which may enable the construction of optically active photonic devices made of silicon.

  6. Strain-engineered MOSFETs

    Maiti, CK

    2012-01-01

    Currently strain engineering is the main technique used to enhance the performance of advanced silicon-based metal-oxide-semiconductor field-effect transistors (MOSFETs). Written from an engineering application standpoint, Strain-Engineered MOSFETs introduces promising strain techniques to fabricate strain-engineered MOSFETs and to methods to assess the applications of these techniques. The book provides the background and physical insight needed to understand new and future developments in the modeling and design of n- and p-MOSFETs at nanoscale. This book focuses on recent developments in st

  7. Highly Strained Organophosphorus Compounds

    Slootweg, J.C.

    2005-01-01

    In our research on small, strained organophosphorus ring systems we became interested in the synthesis and applications of species that are even more strained than the parent phosphirane, by introducing an exocyclic double bond (methylenephosphirane), and by cyclopropyl spirofusion to the edge (e.g

  8. Sprains and Strains

    ... people at risk for strains. Gymnastics, tennis, rowing, golf, and other sports that require extensive gripping can ... Trials and You was designed to help people learn more about clinical trials, why they matter, and ...

  9. The strained state cosmology

    Tartaglia, Angelo

    2015-01-01

    Starting from some relevant facts concerning the behaviour of the universe over large scale and time span, the analogy between the geometric approach of General Relativ- ity and the classical description of an elastic strained material continuum is discussed. Extending the elastic deformation approach to four dimensions it is shown that the accelerated expansion of the universe is recovered. The strain field of space-time repro- duces properties similar to the ones ascribed to the dark energy currently called in to explain the accelerated expansion. The strain field in the primordial universe behaves as radiation, but asymptotically it reproduces the cosmological constant. Subjecting the theory to a number of cosmological tests confirms the soundness of the approach and gives an optimal value for the one parameter of the model, i.e. the bulk modulus of the space-time continuum. Finally various aspects of the Strained State Cosmology (SSC) are discussed and contrasted with some non-linear massive gravity theor...

  10. An Ultrasonic Strain Gauge

    Kersemans, Mathias; Allaer, Klaas; Degrieck, Joris; Van Den Abeele, Koen; Pyl, Lincy; Zastavnik, Filip; Sol, Hugo; Van Paegem, Wim

    2014-01-01

    A method is introduced for the measurements of strain exploiting the interaction between ultrasound waves and characteristics of the insonified specimen. First, the response of obliquely incident harmonic waves to a deterministic surface roughness is utilized. Analysis of backscattered amplitudes in Bragg diffraction geometry then yields a measure for the in-plane strain field by mapping any shift in angular dependency. Secondly, the analysis of the reflection characteristics of normal incide...

  11. MEMS Graphene Strain Sensor

    Young, Clinton Wen-Chieh

    Graphene is a two dimensional honeycomb structure of sp2 hybridized carbon atoms that has possibilities in many applications due to its excellent mechanical and electrical properties. One application for Graphene is in the field of sensors. Graphene's electronic properties do not degrade when it undergoes mechanical strain which is advantageous for strain sensors. In this thesis, certain properties, such as the piezo-resistivity and flexibility, of graphene will be explored to show how they can be utilized to make a strain sensing device. Our original fabrication process of patterning graphene and the transfer process of graphene onto a flexible substrate will be discussed. The development of a stretchable and flexible graphene based rosette strain sensor will also be detailed. Developing a novel, reliable patterning process for the graphene is the first step to manufacture a stretchable graphene based sensor. The graphene was patterned using a photolithography and etching process that was developed by our research team, then it was transferred to a flexible polymer substrate with the use of a combination of soft lithography and wet etching of the Ni foil with ferric chloride solution. Graphene patterning is an essential step in fabricating reliable and sensitive sensors. With this process, graphene can be consistently patterned into different shapes and sizes. To utilize the graphene as the sensing material it also needs to be transferred onto a flexible substrate. The innovative transfer process developed by our research team consistently adheres graphene to a flexible PDMS substrate while removing the original nickel substrate. In the end, the graphene was transferred from the metal substrate to the desired flexible substrate. This process was repeated multiple times to create a stack and multilayer device. While many graphene-based strain sensors have been developed, they are uni-directional and can only measure the strain applied on the sensor in a principle

  12. Longitudinal misalignment based strain sensor

    Andrews, Jeffrey Pratt

    1989-01-01

    A practical fiber optic strain sensor has been developed to measure strains in the range of 0.0 to 2.0 percent strain with a resolution ranging between 10 and 100 microstrain depending on sensor design choices. This intensity based sensor measures strain by monitoring strain induced longitudinal misalignment in a novel fiber interconnection. This interconnection is created by aligning fibers within a segment of hollow core fiber. Related splice loss mechanisms are investigated ...

  13. ConStrains identifies microbial strains in metagenomic datasets.

    Luo, Chengwei; Knight, Rob; Siljander, Heli; Knip, Mikael; Xavier, Ramnik J; Gevers, Dirk

    2015-10-01

    An important fraction of microbial diversity is harbored in strain individuality, so identification of conspecific bacterial strains is imperative for improved understanding of microbial community functions. Limitations in bioinformatics and sequencing technologies have to date precluded strain identification owing to difficulties in phasing short reads to faithfully recover the original strain-level genotypes, which have highly similar sequences. We present ConStrains, an open-source algorithm that identifies conspecific strains from metagenomic sequence data and reconstructs the phylogeny of these strains in microbial communities. The algorithm uses single-nucleotide polymorphism (SNP) patterns in a set of universal genes to infer within-species structures that represent strains. Applying ConStrains to simulated and host-derived datasets provides insights into microbial community dynamics. PMID:26344404

  14. The strained state cosmology

    Tartaglia, Angelo

    2016-01-01

    Starting from some relevant facts concerning the behavior of the universe over large scale and time span, the analogy between the geometric approach of General Relativity and the classical description of an elastic strained material continuum is discussed. Extending the elastic deformation approach to four dimensions it is shown that the accelerated expansion of the universe is recovered. The strain field of space-time reproduces properties similar to the ones ascribed to the dark energy currently called in to explain the accelerated expansion. The strain field in the primordial universe behaves as radiation, but asymptotically it reproduces the cosmological constant. Subjecting the theory to a number of cosmological tests confirms the soundness of the approach and gives an optimal value for the one parameter of the model, i.e. the bulk modulus of the space-time continuum. Finally various aspects of the Strained State Cosmology (SSC) are discussed and contrasted with some non-linear massive gravity theories. The possible role of structure topological defects is also mentioned. The conclusion is that SSC is at least as good as the ΛCDM standard cosmology, giving a more intuitive interpretation of the physical nature of the phenomena.

  15. Novel strained superjunction VDMOS

    Naugarhiya, Alok; Dubey, Shashank; Kondekar, Pravin N.

    2015-09-01

    In this paper, we have proposed novel strained superjunction (s-SJ) vertical double diffused MOS (VDMOS). Through channel engineering, we have introduced strain effects in s-SJ device using thin separate p-type silicon-germanium (p-SiGe) layer over silicon p-pillar. Further, we have designed process flow for the possible fabrication of s-SJ VDMOS. The proposed s-SJ devices fitted with less input capacitance (Cin) and 1.2∼3 times higher output current density than conventional SJ VDMOS. Therefore, 40% less gate charge (Qg) is required to turn-on the s-SJ VDMOS and Ron A is optimized in between 12% and 46%.

  16. Strains in general relativity

    The definition of relative accelerations and strains among a set of comoving particles is studied in connection with the geometric properties of the frame adapted to a 'fiducial observer'. We find that a relativistically complete and correct definition of strains must take into account the transport law of the chosen spatial triad along the observer's congruence. We use special congruences of (accelerated) test particles in some familiar spacetimes to elucidate such a point. The celebrated idea of Szekeres' compass of inertia, arising when studying geodesic deviation among a set of free-falling particles, is here generalized to the case of accelerated particles. In doing so we have naturally contributed to the theory of relativistic gravity gradiometer. Moreover, our analysis was made in an observer-dependent form, a fact that would be very useful when thinking about general relativistic tests on space stations orbiting compact objects like black holes and also in other interesting gravitational situations

  17. Strains in General Relativity

    Bini, Donato; Geralico, Andrea

    2014-01-01

    The definition of relative accelerations and strains among a set of comoving particles is studied in connection with the geometric properties of the frame adapted to a "fiducial observer." We find that a relativistically complete and correct definition of strains must take into account the transport law of the chosen spatial triad along the observer's congruence. We use special congruences of (accelerated) test particles in some familiar spacetimes to elucidate such a point. The celebrated idea of Szekeres' compass of inertia, arising when studying geodesic deviation among a set of free-falling particles, is here generalized to the case of accelerated particles. In doing so we have naturally contributed to the theory of relativistic gravity gradiometer. Moreover, our analysis was made in an observer-dependent form, a fact that would be very useful when thinking about general relativistic tests on space stations orbiting compact objects like black holes and also in other interesting gravitational situations.

  18. Geodetic surveying of strains

    Meixner, H.

    1980-11-01

    This article evaluates methods and apparatus used in the German Democratic Republic to assess vertical and horizontal deformations and strains caused by coal mining and mining of other deposits. Each of the methods is characterized; type of measuring apparatus and its accuracy is given. The following conventional methods of surveying are characterized: (I.) vertical strains: measurement with hydrostatic tube balance (apparatus produced by the Praezisionsmechanik Freiberg, with accuracy of 0.01 mm), trigonometric levelling (error up to 10 mm), geometric levelling (NI 007 and NI 008 apparatus produced by Carl Zeiss JENA), and direct height measuring; (II.) horizontal strains: direct surveying with accuracy higher than 5 mm/50 m, indirect surveying (theodolite THEO 010 A produced by the Carl Zeiss JENA), and alignment method (using apparatus produced by Praezisionsmechanik, Freiberg). Advanced surveying methods are also discussed: electro-optical method (using EOK 2000 range finder produced by Carl Zeiss JENA, with average error ranging from 5 mm to 10 mm), laser method (LF-1 and LFG-1 lasers produced by Carl Zeiss JENA), measuring gyroscope used to measure contorsion (MRK 2 gyroscope produced by the Praezisionsmechanik, Freiberg); photogrammetry: stereophotogrammetry and so-called parallel photogrammetry. (15 refs.) (In Polish)

  19. Temperature controlled strain gaged extensometer

    Ramos, G. L.; Seplow, S.

    1968-01-01

    Temperature controlled strain-gaged extensometer measures longitudinal and girth deflections of pressure vessels in excess of one percent strain during pressurization and depressurization with cryogenic fluids at cryogenic temperatures. The device is of beryllium-copper strips.

  20. MEMS Resonant Strain Sensor Integration

    Myers, David Richard

    2010-01-01

    Despite commercial availability since the 1950's, silicon strain sensors have not experienced the same success as other microdevices, such as accelerometers, pressure sensors, and inkjet heads. Strain sensors measure mechanical deformation and could be used in many structural components, improving safety, controls, and manufacturing tolerances. This thesis examines major strain sensing techniques and highlights both advantages and disadvantages of each. MEMS resonant strain gauges are iden...

  1. Strain calibration of optical FBG-based strain sensors

    Roths, Johannes; Wilfert, Andre; Kratzer, Peter; Jülich, Florian; Kuttler, Rolf

    2010-09-01

    A facility for strain sensitivity calibration of optical FBG-based strain sensors according to the German VDI/VDE 2660 guideline was established and characterized. Statistical analysis of several calibration measurement series performed with one single type of FBG strain sensor and application technique showed a reproducibility of 0.15%. Strain sensitivities for FBGs inscribed in two different types of optical fibres (GF1B and PR2008) showed significantly different strain sensitivities of k = 0.7885+/-0.0026 and k = 0.7758+/-0.0024, respectively.

  2. Precision determination of strains by strain measurement method

    Method for precision strain measurement determination of strains measurement determination of strains by direct measurement of the resistance of strain gauge resistors put on the sample, by constant current bridge MOD-61 of 0.05 class using a zero method by single bridge double-clamp circuit is described. Strain measurement technique was used to investigate residual stresses in tubular samples. Sample external diameter made up 30 mm, the length - 180, the wall thickness-11 mm. To evaluate the method sensitivity, annealed samples were investigated (annealing temperature-850-880 deg C, hold-up-2 h, cooling in the furnace). It is ascertained, that the method provides for 0.3-0.5 μm strain measurement accuracy even if sample strains do not exceed 3.0-3.6 μm and correspond to residual stress level of no more than 20 MPa

  3. Development of reversible strain gage

    A high-temperature strain gage which can be peeled after taking required apparent strain measurements in a furnace and can be attached reverse-side-up at the point of interest on a test structure was developed. Using the ''reversible'' strain gage with selected room-temperature curing type polyester adhesive, one can expect to measure thermal strain accurately, especially for on large structures, at the first test in temperature up to 250 deg C. The repeatability of apparent strains for about 100 reversible gages was within 50 microstrains of difference at 250 deg C (within 30 microstrains of difference for 80 % of the test gages). (author)

  4. [Echinococcus and strain concepts].

    Utük, Armağan Erdem; Simsek, Sami

    2008-01-01

    Hydatid disease (echinococcosis) is one of the most important parasitic zoonoses and remains a public health and economic problem all over the world. Echinococcus granulosus includes a number of genetic variants and, up to date, analyses of mitochondrial DNA sequences have identified ten distinct genetic types (genotypes G1-10). This categorization follows closely the pattern of strain variation emerging based on biological characteristics. The extensive variation in E. granulosus may influence life-cycle patterns, host specificity, development rate, antigenicity, transmission dynamics, sensitivity to chemotherapeutic agents, and pathology. In this review, the recent genetic characterizations of Echinococcus genus have been summarized. PMID:18351549

  5. Asymptomatic bacteriuria Escherichia coli strains

    Hancock, Viktoria; Nielsen, E.M.; Klemm, Per

    2006-01-01

    Urinary tract infections (UTIs) affect millions of people each year. Escherichia coli is the most common organism associated with asymptomatic bacteriuria (ABU) in humans. Persons affected by ABU may carry a particular E. coli strain for extended periods of time without any symptoms. In contrast to...... uropathogenic E. coli (UPEC) that cause symptomatic UTI, very little is known about the mechanisms by which these strains colonize the urinary tract. Here, we have investigated the growth characteristics in human urine as well as adhesin repertoire of nine ABU strains; the ability of ABU strains to compete...... against the UPEC strain CFT073 was also studied. The different ABU strains displayed a wide variety of the measured characteristics. Half of the ABU strains displayed functional type 1 fimbriae while only one expressed functional P fimbriae. A good correlation between the growth rate of a particular...

  6. Reconstruction of axisymmetric strain distributions via neutron strain tomography

    Predicting the behaviour of structural components under a particular set of loading conditions requires knowledge of the residual elastic strain distribution throughout the bulk of these components. Characterising the 3D strain state at any particular point involves the measurement of six independent components which make up the second order strain tensor. Mapping the complete strain distribution throughout large volumes thus presents significant practical challenges. One possible solution to this problem is to reconstruct the 3D variation of strain components using tomographic techniques. The basic principle underpinning this idea is that the multi-component strain tensor can be reconstructed from a redundant set of lower order projection data. Here we demonstrate this fundamental concept for two samples: a shrink fit ‘ring-and-plug’ sample, and a spray-quenched circular cylinder, both possessing axially symmetric internal strain distribution. We present and contrast different approaches to the strain tomography problem. The methods described here can also be readily applied to high-energy X-ray diffraction measurements and represent an important step toward developing the tomographic reconstruction framework for strain tensor distributions of arbitrary complexity. The major benefit of neutron strain tomography is that the incident beam flux is utilised more fully, greatly reducing the data collection times. Using micro-channel plate (MCP) neutron detectors, a spatial resolution of the order of 0.1 mm can be achieved .

  7. Strain in silicon nanowire beams

    Ureña, Ferran; Olsen, Sarah H.; Šiller, Lidija; Bhaskar, Umesh; Pardoen, Thomas; Raskin, Jean-Pierre

    2012-12-01

    In this work, strain in silicon free standing beams loaded in uniaxial tension is experimentally and theoretically investigated for strain values ranging from 0 to 3.6%. The fabrication method allows multiple geometries (and thus strain values) to be processed simultaneously on the same wafer while being studied independently. An excellent agreement of strain determined by two non-destructive characterization techniques, Raman spectroscopy and mechanical displacement using scanning electron microscopy (SEM) markers, is found for all the sample lengths and widths. The measured data also show good agreement with theoretical predictions of strain based upon continuum mechanical considerations, giving validity to both measurement techniques for the entire range of strain values. The dependence of Young's modulus and fracture strain on size has also been analyzed. The Young's modulus is determined using SEM and compared with that obtained by resonance-based methods. Both methods produced a Young's modulus value close to that of bulk silicon with values obtained by resonance-based methods being slightly lower. Fracture strain is analyzed in 40 sets of samples with different beam geometries, yielding values up to 3.6%. The increase in fracture strain with decreasing beam width is compared with previous reports. Finally, the role of the surface on the mechanical properties is analyzed using UV and visible lasers having different penetration depths in silicon. The observed dependence of Raman shift on laser wavelength is used to assess the thermal conductivity of deformed silicon.

  8. Asymptomatic bacteriuria Escherichia coli strains

    Hancock, Viktoria; Nielsen, E.M.; Klemm, Per

    2006-01-01

    Urinary tract infections (UTIs) affect millions of people each year. Escherichia coli is the most common organism associated with asymptomatic bacteriuria (ABU) in humans. Persons affected by ABU may carry a particular E. coli strain for extended periods of time without any symptoms. In contrast to...... uropathogenic E. coli (UPEC) that cause symptomatic UTI, very little is known about the mechanisms by which these strains colonize the urinary tract. Here, we have investigated the growth characteristics in human urine as well as adhesin repertoire of nine ABU strains; the ability of ABU strains to compete...

  9. Hydrogen production from microbial strains

    Harwood, Caroline S; Rey, Federico E

    2012-09-18

    The present invention is directed to a method of screening microbe strains capable of generating hydrogen. This method involves inoculating one or more microbes in a sample containing cell culture medium to form an inoculated culture medium. The inoculated culture medium is then incubated under hydrogen producing conditions. Once incubating causes the inoculated culture medium to produce hydrogen, microbes in the culture medium are identified as candidate microbe strains capable of generating hydrogen. Methods of producing hydrogen using one or more of the microbial strains identified as well as the hydrogen producing strains themselves are also disclosed.

  10. Will the swine strain crowd out the seasonal influenza strain?

    Schinazi, Rinaldo B

    2010-01-01

    We use spatial and non spatial models to argue that competition alone may explain why two influenza strains do not usually coexist. The more virulent strain is likely to crowd out the less virulent one. This can be seen as a consequence of the Exclusion Principle of Ecology. We exhibit, however, a spatial model for which coexistence is possible.

  11. Tissue Velocity, Strain und Strain Rate bei Hunden mit Mitralklappenendokardiose

    Javornik, Ana

    2007-01-01

    In der vorliegenden Arbeit „Tissue Velocity, Strain und Strain Rate bei Hunden mit Mitralklappenendokardiose“ wurden erstmals die Geschwindigkeits- und Verformungsparameter zur Evaluierung von Hunden mit Mitralklappenendokardiose angewendet. Diese erweisen sich als neue und viel versprechende Möglichkeiten zur Quantifizierung der regionalen Myokardfunktion. Die myokardialen Funktionsparameter finden in der Humanmedizin weit verbreitete Anwendung und auch in der Tiermedizin erlangen sie zunehm...

  12. TL transgenic mouse strains

    As a result of abnormal development of the thymus of these mice, TCR αβ lineage of the T cell differentiation is disturbed and cells belonging to the TCR γδ CD4- CD8- double negative (DN) lineage become preponderant. The γδ DN cells migrate into peripheral lymphoid organs and constitute nearly 50% of peripheral T cells. Immune function of the transgenic mice is severely impaired, indicating that the γδ cells are incapable of participating in these reactions. Molecular and serological analyses of T-cell lymphomas reveal that they belong to the γδ lineage. Tg.Tlaa-3-1 mice should be useful in defining the role of TL in normal and abnormal T cell differentiation as well as in the development of T-cell lymphomas, and further they should facilitate studies on the differentiation and function of γδ T cells. We isolated T3b-TL gene from B6 mice and constructed a chimeric gene in which T3b-TL is driven by the promoter of H-2Kb. With the chimeric gene, two transgenic mouse strains, Tg. Con.3-1 and -2 have been derived in C3H background. Both strains express TL antigen in various tissues including skin. The skin graft of transgenic mice on C3H and (B6 X C3H)F1 mice were rejected. In the mice which rejected the grafts, CD8+TCRαβ cytotoxic T cells (CTL) against TL antigens were recognized. The recognition of TL by CTL did not require the antigen presentation by H-2 molecules. The results indicated that TL antigen in the skin becomes a transplantation antigen and behaves like a typical allogeneic MHC class I antigen. The facts that (B6 X C3H)F1 mice rejected the skin expressing T3b-TL antigen and induced CTL that killed TL+ lymphomas of B6 origin revealed that TL antigen encoded by T3b-TL is recognized as non-self in B6 mice. Experiments are now extended to analyze immune responses to TL antigen expressed on autochthonous T cell lymphomas. (J.P.N.)

  13. What Are Sprains and Strains?

    ... and Strains Find a Clinical Trial Journal Articles Sprains and Strains PDF Version Size: 119 KB Audio Version Time: 07: ... Twist a knee. Where Do Sprains Usually Occur? Sprains happen most often in the ankle. Sometimes when people fall and land on their ...

  14. Strain measurements at railway wheels

    The development of the radial strain component in railway wheels was investigated by neutron diffraction. In the as manufactured state four railway wheels were investigated. In all four wheels no significant strains were found. After 18,400 km usage first strain gradients close to the outer surface of the wheels were detected. In axial middle ranges the changes in strain are weak. After an usage of 61,000 km the gradients becomes strong at the axial outer position between about +700 με close below the tread and -500 με in a depth of 12.5 mm below the tread. At axial middle positions also strain gradients are formed. The end of live state (510,000 km) differs only slightly from the state measured after a usage of 61,000 km

  15. Pin clad strains in Phenix

    The Phenix reactor has operated for 4 years in a satisfactory manner. The first 2 sub-assembly loadings contained pins clad in solution treated 316. The principal pin strains are: diametral strain (swelling and irradiation creep), ovality and spiral bending of the pin (interaction of wire and pin cluster and wrapper). A pin cluster irradiated to a dose of 80 dpa F reached a pin diameter strain of 5%. This strain is principally due to swelling (low fission gas pressure). The principal parameters governing the swelling are instantaneous dose, time and temperature for a given type of pin cladding. Other types of steel are or will be irradiated in Phenix. In particular, cold-worked titanium stabilised 316 steel should contribute towards a reduction in the pin clad strains and increase the target burn-up in this reactor. (author)

  16. Recent advances in echocardiography: strain and strain rate imaging

    Mirea, Oana; Duchenne, Jurgen; Voigt, Jens-Uwe

    2016-01-01

    Deformation imaging by echocardiography is a well-established research tool which has been gaining interest from clinical cardiologists since the introduction of speckle tracking. Post-processing of echo images to analyze deformation has become readily available at the fingertips of the user. New parameters such as global longitudinal strain have been shown to provide added diagnostic value, and ongoing efforts of the imaging societies and industry aimed at harmonizing methods will improve the technique further. This review focuses on recent advances in the field of echocardiographic strain and strain rate imaging, and provides an overview on its current and potential future clinical applications.

  17. Magnetostriction strain measurement: heterodyne laser interferometry versus strain gauge technique

    Gorji Ghalamestani, Setareh; Vandevelde, Lieven; J.J. Dirckx, Joris; Melkebeek, Jan

    2013-01-01

    Deformation of the ferromagnetic material, known as magnetostriction, causes vibrations and noise of electrical machines and transformer cores. A setup by using heterodyne laser interferometers has been built to measure the magnetostriction strains as a function of the applied magnetic field. The measurement results on a sample of nonoriented electrical steel are presented in this work. These results are compared with those obtained by using a strain gauge setup. The laser measurements are l...

  18. Mercury retention in several strains and strain crosses of chickens

    Miller, V.L.; Bearse, G.E.; Csonka, E.

    1970-01-01

    The retention of mercury from injections of mercuric chloride was determined in 32 samples of chicks from various strains and strain crosses of egg type stock. The chicks retaining the most mercury had some four times as much mercury in the liver and kidneys as the chicks retaining the lowest amount. The chicks selected for resistance to leukosis retained more mercury than the susceptible chicks within several leukosis breeding programs.

  19. Low TCR nanocomposite strain gages

    Gregory, Otto J. (Inventor); Chen, Ximing (Inventor)

    2012-01-01

    A high temperature thin film strain gage sensor capable of functioning at temperatures above 1400.degree. C. The sensor contains a substrate, a nanocomposite film comprised of an indium tin oxide alloy, zinc oxide doped with alumina or other oxide semiconductor and a refractory metal selected from the group consisting of Pt, Pd, Rh, Ni, W, Ir, NiCrAlY and NiCoCrAlY deposited onto the substrate to form an active strain element. The strain element being responsive to an applied force.

  20. Main: 1C2A [RPSD[Archive

    Full Text Available re Molecule: Bowman-Birk Trypsin Inhibitor; Chain: A Hydrolase Inhibitor H.K.Song, Y.S.Kim, J.K.Yang, J.Moon..., J.Y.Lee, S.W.Suh H.K.Song, Y.S.Kim, J.K.Yang, J.Moon, J.Y.Lee, S.W.Suh Crystal Structure Of A 16 Kda Doubl

  1. V18P9C2. A complex phosphide carbide

    V18P9C2 crystallizes in the orthorhombic space group Pmma with the lattice parameters a = 17.044(3), b = 3.2219(7), and c = 13.030(2) Aa, Z = 2. The crystal structure is composed of 19 symmetry-independent atoms. The crystal structure is considered as a network formed by the transition metal atoms exhibiting cubic, trigonal prismatic, and octahedral voids centered by V, P, and C atoms, respectively. Vice versa, the V and P atoms form a three-dimensional network. The two CV6 octahedra are edge- and corner-connected to chains running parallel to [010]. The five unique P atoms are trigonal prismatically coordinated by V atoms with one to three faces capped again by a V atom. The V atoms have mainly cubic environments formed solely by V or by V and P atoms. V18P9C2 exhibits some structural relations to other compounds of the ternary system V-P-C as well as to other intermetallic phases. Despite the low carbon content, V18P9C2 is considered as a ternary compound rather than an interstitially stabilized (binary) phosphide in view of its special structural features.

  2. Roll bonding of strained aluminium

    Staun, Jakob M.

    2003-01-01

    This report investigates roll bonding of pre-strained (å ~ 4) aluminium sheets to produce high strain material from high purity aluminium (99.996%) and commercial pure aluminium (99.6%). The degree of bonding is investigated by optical microscopy and ultrasonic scanning. Under the right...... circumstances both materials show good bonding, but the high purity material is excluded because of recrystallisation and the resulting loss of mechanical properties. The effect of cross stacking and roll bonding pre-strained sheets of the commercial purity material is investigated and some dependence of the...... cross rolled volume fraction is found. To further asses this effect, and the anisotropy, it is necessary to acquire knowledge about both texture and microstructure, e.g. by TEM. Roll bonding of pre-strained aluminium is found to be a possible alternative to ARB in the quest for ultra-fine grained...

  3. Covalent functionalization of strained graphene

    Boukhvalov, Danil W.; Son, Young-Woo

    2012-01-01

    Enhancement of the chemical activity of graphene is evidenced by first-principles modelling of chemisorption of the hydrogen, fluorine, oxygen and hydroxyl groups on strained graphene. For the case of negative strain or compression, chemisorption of the single hydrogen, fluorine or hydroxyl group is energetically more favourable than those of their pairs on different sublattices. This behaviour stabilizes the magnetism caused by the chemisorption being against its destruction by the pair form...

  4. Hypervirulent strains of Clostridium difficile

    Cookson, Barry

    2007-01-01

    North America has seen increasing numbers of hospitalised patients and others in nursing homes and the community, with more severe Clostridium difficile associated diarrhoea. This is also described in Northern Europe and surveillance systems are being developed or improved to monitor the situation. One strain (ribotype O27) is described in detail and, like other emerging strains, is demonstrating increasing antimicrobial resistance, notably to quinolone antibiotics. However, its association w...

  5. Biocontrol mechanisms of Thrichoderma strains

    Benítez Fernández, Concepción Tahía; Rincón Romero, Ana María; Limón Mirón, María del Carmen; Carballo Codón, Antonio

    2004-01-01

    The genus Trichoderma comprises a great number of fungal strains that act as biological control agents, the antagonistic properties of which are based on the activation of multiple mechanisms. Trichoderma strains exert biocontrol against fungal phytopathogens either indirectly, by competing for nutrients and space, modifying the environmental conditions, or promoting plant growth and plant defensive mechanisms and antibiosis, or directly, by mechanisms such as mycoparasitism. These indirect a...

  6. Strain evaluation in fatigue analysis

    Thermoplastic analysis and more precisely fatigue analysis of nuclear components working at high temperature is usually very difficult and very expensive. Simplified methods have been proposed and are generally used to perform analysis of these structures. These simplified methods require elastic analysis of the component. For a fatigue analysis it is necessary to obtain a very precise value of the strains so the elastic strains must be corrected in order to take plasticity into account. This later appears in two different ways. Non linearity of material which induces strain amplification when working in the plastic field especially near by geometric discontinuities. That can be taken into account with a coefficient Ke. Triaxiality and isovolumic character of strains in the plastic field. That also induces strain amplification with regard to elastic computation. It is proposed in this work to introduce a coefficient Kv to estimate this strain amplification. Several elastic and plastic calculations for typical geometries, have been done in order to test the importance of these parameters and to set up methods for evaluating the coefficients Ke and Kv

  7. Genome Sequence of Pseudomonas chlororaphis Strain 189

    Town, Jennifer; Audy, Patrice; Boyetchko, Susan M.

    2016-01-01

    Pseudomonas chlororaphis strain 189 is a potent inhibitor of the growth of the potato pathogen Phytophthora infestans. We determined the complete, finished sequence of the 6.8-Mbp genome of this strain, consisting of a single contiguous molecule. Strain 189 is closely related to previously sequenced strains of P. chlororaphis. PMID:27340063

  8. Strain Growth in Containment Vessels

    DONG Q; LI Q M; ZHENG J Y

    2006-01-01

    Strain growth is a phenomenon observed in containment vessels subjected to internal blast loading.The elastic response of the vessel may become larger in a later stage compared to its response during the initial stage.The dynamic responses of infinitely long cylindrical containment vessels subjected to uniformly-distributed internal blast loading are studied using LS-DYNA.The development of bending modes and the interaction between the breathing mode and bending modes are observed.The methodology developed for dynamic elastic buckling analysis is employed to study the strain growth phenomenon in explosion containment vessels.It is shown that the dynamic instable vibration of a containment vessel is the basic mechanism of strain growth.

  9. Thermoelectric properties of strained silicon

    Hinsche, Nicki F.; Zahn, Peter [Martin-Luther-Universitaet, Institut fuer Physik, Von-Seckendorff-Platz 1, 06120 Halle/S. (Germany); Mertig, Ingrid [Martin-Luther-Universitaet, Institut fuer Physik, Von-Seckendorff-Platz 1, 06120 Halle/S. (Germany); Max-Planck-Institut fuer Mikrostrukturphysik, Weinberg 2, D-06120 Halle (Germany)

    2011-07-01

    Starting from bulk silicon, we study the change in thermoelectric properties due to symmetry breaking in rolled-up and layered Si which might lead to nanostructured thermoelectrics. Valley splitting in strained Si caused by tetragonal distortion was studied recently with respect to the enhancement of electron mobility. Our results show that the tetragonal distortion has a strong influence on the electronic transport properties. The electronic structure is calculated self consistently within the framework of density functional theory. The transport properties are studied in the diffusive limit applying the Boltzmann theory in relaxation time approximation. In detail, the anisotropy of the electrical conductivity, the thermopower and the resulting powerfactor in the in-plane and off-plane directions are studied in dependence on strain, doping level and temperature. It is shown, that the powerfactor at a given temperature can be enhanced slightly by strain for p-doping, while no enhancement is obtained for n-doping.

  10. Spin transport in graphene superlattice under strain

    Sattari, Farhad

    2016-09-01

    In this paper, the spin-dependent transport and the spin polarization properties for graphene superlattice with Rashba spin-orbit interaction (RSOI) in the presence of zigzag and armchair direction strain are studied. It is found that for the zigzag direction strain the angular range of the spin-inversion can be efficiently controlled by the strain strength. In addition, the efficiency of spin-inversion and spin-dependent conductivity decreases by increasing the strain strength. When the armchair direction strain is applied to a monolayer graphene superlattice the spin polarization can be observed and increases by increasing the strain strength, whereas for the zigzag direction strain it is zero.

  11. Myocardial Strain and Strain Rate Imaging: Comparison between Doppler Derived Strain Imaging and Speckle Tracking Echocardiography

    Anita Sadeghpour

    2013-05-01

    Full Text Available Regional myocardial function has been traditionally assessed by visual estimation (1. Echocardiographic strain imaging which is known as deformation imaging, has been emerged as a quantitative technique to accurately estimate regional myocardial function and contractility. Currently, strain imaging has been regarded as a research tool in the most echocardiography laboratories. However, in recent years, strain imaging has gain momentum in daily clinical practice (2. The following two techniques have dominated the research arena of echocardiography: (1 Doppler based tissue velocity measurements, frequently referred to tissue Doppler or myocardial Doppler, and (2 speckle tracking on the basis of displacement measurements (3. Over the past two decades, Tissue Doppler Imaging (TDI and Doppler –derived strain (S and strain rate (SR imaging were introduced to quantify regional myocardial function. However, Doppler–derived strain variables faced criticisms, with regard to the angle dependency, noise interference, and substantial intraobserver and interobserver variability. The angle dependency is the major weakness of Doppler based methodology; however, it has the advantage of online measurements of velocities and time intervals with excellent temporal resolution, which is essential for the assessment of ischemia (4. Speckle-tracking echocardiography (STE or Non Doppler 2D strain echocardiography is a relatively new, largely angle-independent technique that analyzes motion by tracking natural acoustic reflections and interference patterns within an ultrasonic window. The image-processing algorithm tracks elements with approximately 20 to 40 pixels containing stable patterns and are described as ‘‘speckles’’ or ‘‘fingerprints’’. The speckles seen in grayscale B-mode (2D images are tracked consecutively frame to frame (5, 6. Assessment of 2D strain by STE is a semiautomatic method that requires definition of the myocardium

  12. Photoacoustic spectroscopy of Entamoeba histolytica strains

    Acosta-Avalos, D.; Alvarado-Gil, J. J.; Silva, E. F.; Orozco, E.; de Menezes, L. F.; Vargas, H.

    2005-06-01

    Pathogenic and non-pathogenic strains of E. histolytica are studied using photoacoustic spectroscopy. It is shown that the pathogenic strain presents a spectrum similar to that of iron sulfur proteins. The non-pathogenic strain does not show any relevant absorption at the studied wavelength range. The differences observed between the optical absorption spectra of both strains opens the possibility of using photoacoustic spectroscopy as a reliable and simple technique to identify different types of E. histolytica strains.

  13. Computational Strain Gradient Crystal Plasticity

    Niordson, Christian Frithiof; Kysar, Jeffrey W.

    2011-01-01

    A model for strain gradient crystal visco-plasticity is formulated along the lines proposed by Fleck andWillis (2009) for isotropic plasticity. Size-effects are included in the model due to the addition of gradient terms in both the free energy as well as through a dissipation potential. A finite...

  14. Job strain and alcohol intake

    Heikkilä, Katriina; Nyberg, Solja T; Fransson, Eleonor I;

    2012-01-01

    The relationship between work-related stress and alcohol intake is uncertain. In order to add to the thus far inconsistent evidence from relatively small studies, we conducted individual-participant meta-analyses of the association between work-related stress (operationalised as self-reported job...... strain) and alcohol intake....

  15. Trials with a Strain Gauge.

    Auty, Geoff

    1996-01-01

    Describes an attempt to match the goals of the practical demonstration of the use of a strain gauge and the technical applications of science and responding to student questions in early trials, while keeping within the level of electronics in advanced physics. (Author/JRH)

  16. Material mechanical characterization method for multiple strains and strain rates

    Erdmand, III, Donald L.; Kunc, Vlastimil; Simunovic, Srdjan; Wang, Yanli

    2016-01-19

    A specimen for measuring a material under multiple strains and strain rates. The specimen including a body having first and second ends and a gage region disposed between the first and second ends, wherein the body has a central, longitudinal axis passing through the first and second ends. The gage region includes a first gage section and a second gage section, wherein the first gage section defines a first cross-sectional area that is defined by a first plane that extends through the first gage section and is perpendicular to the central, longitudinal axis. The second gage section defines a second cross-sectional area that is defined by a second plane that extends through the second gage section and is perpendicular to the central, longitudinal axis and wherein the first cross-sectional area is different in size than the second cross-sectional area.

  17. Engineering piezoresistivity using biaxially strained silicon

    Pedersen, Jesper Goor; Richter, Jacob; Brandbyge, Mads;

    2008-01-01

    piezocoefficient on temperature and dopant density is altered qualitatively for strained silicon. In particular, we find that a vanishing temperature coefficient may result for silicon with grown-in biaxial tensile strain. These results suggest that strained silicon may be used to engineer the iezoresistivity to......We calculate the shear piezocoefficient of p-type silicon with grown-in biaxial strain using a 66 k·p method. We find a significant increase in the value of the shear piezocoefficient for compressive grown-in biaxial strain, while tensile strain decreases the piezocoefficient. The dependence of the...

  18. Plane strain test for metal sheet characterization

    Flores, Paulo; Bonnet, Félix; Habraken, Anne

    2007-01-01

    This article shows the influence of a plane strain test specimen geometry on the measurable strain field and the influence of free edge effects over the stress computation. The experimental strain field distribution is measured over the whole deformable zone of a plane strain test specimen by an optical strain gauge. The chosen material is the DC06 IF steel of 0.8 mm thickness. The stress field is computed for several geometries at different strain levels by a Finite Element (FE) commer...

  19. Computational strain gradient crystal plasticity

    Niordson, Christian Frithiof; Kysar, Jeffrey W.

    2014-01-01

    A numerical method for viscous strain gradient crystal plasticity theory is presented, which incorporates both energetic and dissipative gradient effects. The underlying minimum principles are discussed as well as convergence properties of the proposed finite element procedure. Three problems...... of plane crystal plasticity are studied: pure shear of a single crystal between rigid platens as well as plastic deformation around cylindrical voids in hexagonal close packed and face centered cubic crystals. Effective in-plane constitutive slip parameters for plane strain deformation of specifically...... oriented face centered cubic crystals are developed in terms of the crystallographic slip parameters. The effect on geometrically necessary dislocation structures introduced by plastic deformation is investigated as a function of the ratio of void radius to plasticity length scale....

  20. Electronic Transport in Strained Graphene

    Aguilera, Juan Luis

    2015-01-01

    Graphene is a single atomic layer material with exceptional electronic and mechanical properties. Graphene has formed the basis of many nanoelectromechanical and strain sensing devices. However, the ultimate limit of miniaturization of such sensors has not yet been ascertained. In this work we present the fabrication and electrical characterization of nanoscale pressure sensors realized from suspended graphene membrane devices.We start in chapter 1 by describing the elemental electronic prope...

  1. Using Strain Analysis For Landslides

    Talich, Milan

    Vol. 4. Kyoto : International Consortium on Landslides (ICL), 2014, s. 178-184. [World Landslide Forum 3. Beijing (CN), 02.06.2014-06.06.2014] R&D Projects: GA MPO FR-TI4/436 Institutional support: RVO:67985556 Keywords : strain analysis * deformation analysis * displacement vectors * mechanics of continuum * landslides Subject RIV: DE - Earth Magnetism, Geodesy, Geography http://library.utia.cas.cz/separaty/2015/ZOI/talich-0443019.pdf

  2. Temperature-Compensating Inactive Strain Gauge

    Moore, Thomas C., Sr.

    1993-01-01

    Thermal contribution to output of active gauge canceled. High-temperature strain gauges include both active gauge wires sensing strains and inactive gauge wires providing compensation for thermal contributions to gauge readings. Inactive-gauge approach to temperature compensation applicable to commercially available resistance-type strain gauges operating at temperatures up to 700 degrees F and to developmental strain gauges operating at temperatures up to 2,000 degrees F.

  3. Strain Monitoring of Flexible Structures

    Litteken, Douglas A.

    2017-01-01

    , such as tensile testing, fatigue testing, and shear testing, but common measurement techniques cannot be used on fabric. Measuring strain in a material and during a test is a critical parameter for an engineer to monitor the structure during the test and correlate to an analytical model. The ability to measure strain in fabric structures is a challenge for NASA. Foil strain gauges, for example, are commonplace on metallic structures testing, but are extremely difficult to interface with a fabric substrate. New strain measuring techniques need to be developed for use with fabric structures. This paper investigates options for measuring strain in fabric structures for both ground testing and in-space structural health monitoring. It evaluates current commercially available options and outlines development work underway to build custom measurement solutions for NASA's fabric structures.

  4. Haemophilus ducreyi Cutaneous Ulcer Strains Are Nearly Identical to Class I Genital Ulcer Strains.

    Dharanesh Gangaiah

    Full Text Available Although cutaneous ulcers (CU in the tropics is frequently attributed to Treponema pallidum subspecies pertenue, the causative agent of yaws, Haemophilus ducreyi has emerged as a major cause of CU in yaws-endemic regions of the South Pacific islands and Africa. H. ducreyi is generally susceptible to macrolides, but CU strains persist after mass drug administration of azithromycin for yaws or trachoma. H. ducreyi also causes genital ulcers (GU and was thought to be exclusively transmitted by microabrasions that occur during sex. In human volunteers, the GU strain 35000HP does not infect intact skin; wounds are required to initiate infection. These data led to several questions: Are CU strains a new variant of H. ducreyi or did they evolve from GU strains? Do CU strains contain additional genes that could allow them to infect intact skin? Are CU strains susceptible to azithromycin?To address these questions, we performed whole-genome sequencing and antibiotic susceptibility testing of 5 CU strains obtained from Samoa and Vanuatu and 9 archived class I and class II GU strains. Except for single nucleotide polymorphisms, the CU strains were genetically almost identical to the class I strain 35000HP and had no additional genetic content. Phylogenetic analysis showed that class I and class II strains formed two separate clusters and CU strains evolved from class I strains. Class I strains diverged from class II strains ~1.95 million years ago (mya and CU strains diverged from the class I strain 35000HP ~0.18 mya. CU and GU strains evolved under similar selection pressures. Like 35000HP, the CU strains were highly susceptible to antibiotics, including azithromycin.These data suggest that CU strains are derivatives of class I strains that were not recognized until recently. These findings require confirmation by analysis of CU strains from other regions.

  5. Lewis Strain Gauge Laboratory: Status and plans

    An in-house lab was established for developing, testing, and evaluating high-temperature strain gauges and to aid in in-house applications of high-temperature strain instrumentation. The lab is automated to provide computer control of oven temperatures, imposed strain, and data sampling

  6. Influence of particles on work hardening strain and recovery strain

    Blum, W.; Dvořák, Jiří; Král, Petr; Sklenička, Václav

    Brno: Ústav fyziky materiálů AV ČR, v. v. i., 2015 - (Dlouhý, A.; Kunz, L.). s. 137-137 ISBN 978-80-87434-07-9. [ICSMA-17 International Conference on the Strength of Materials /17./. 09.08.2015-14.08.2015, Brno] R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : recovery strain * CuZr particles * crystallite boundaries * work hardening Subject RIV: JG - Metallurgy

  7. Sensibility of different wheat varieties (strains) to Ar+ implantation

    The sensibility of different wheat varieties (strains) to Ar+ implantation was studied. The results showed that the survival rate of 21 wheat varieties (strains) at the dose of 6 x 1016 Ar+/cm2 could be divided into five groups: surplus sensitive varieties (strains), sensitive varieties (strains), transitional varieties (strains), obtuse varieties (strains) and surplus obtuse varieties (strains). The sensibility of wheat varieties (strains) to Ar+ injection is high-moisture-fertility wheat varieties (strains) > medium-moisture-fertility wheat varieties (strains) > dry land wheat varieties (strains). The study has provided theoretical basis in induced mutation medial lethal dose of different wheat varieties (strains) to Ar+ implantation. (authors)

  8. Monoclonal antibodies to Toxoplasma gondii strain 119 identify recently isolated Danish strains as one group

    Jensen, L.; Petersen, E.; Henriksen, S.A.; Dietz, Hans-Henrik; Lind, Peter

    1998-01-01

    Four mAb raised against the Danish Toxoplasma gondii strain 119, were selected by screening hybridoma supernatants by indirect immunofluorescence against tachyzoites of the RH strain in order to obtain strain restricted markers. Strain restriction extended beyond discrimination of the 119 and RH...

  9. Local strains in waste tank deflagration analysis

    In recent years extensive effort has been expended to qualify buried nuclear waste storage tanks under accident conditions. One of these conditions is deflagration of the combustible gases which may build up over time. While much work has been done to calculate the general strain state, less effort has been made to address the local strains at structural discontinuities. An analytical method is presented for calculating these local strains and combining them with the general strain state. A closed form solution of the local strains is compared to a finite element solution

  10. Spontaneous abortion and physical strain around implantation

    Hjollund, N H; Jensen, Tina Kold; Bonde, Jens Peter;

    2000-01-01

    Existing studies of physical strain and spontaneous abortion are mainly retrospective or based only on pregnancies that have survived the first trimester. Furthermore, almost all studies have relied on averaged measures of physical strain, which tend to blur an effect if peak values during short...... pregnancy the women recorded physical strain prospectively in a structured diary. Physical strain around the time of implantation was associated with later spontaneous abortion. The adjusted risk ratio for women who reported physical strain higher than average at day 6 to 9 after the estimated date of...

  11. Transient temperature response of strain gages

    When an electrical resistance strain gage bonded to a material is subjected to a temperature change, the resistance of the strain gage changes even though the material is free of stress. This temperature-induced resistance change is generally expressed in strain units and is commonly called apparent strain or thermal output. The thermal expansion coefficients and the temperature coefficient of resistance are temperature-dependent quantities and not necessarily linearly related to temperature. For transient temperature conditions, the two temperatures are different. The magnitude and effect of this temperature difference on apparent strain is studied

  12. Strain Engineering of Transition Metal Dichalcogenides

    Dadgar, Ali; Pasupathy, Abhay; Herman, Irving; Wang, Dennis; Kang, Kyungnam; Yang, Eui-Hyeok

    The application of strain to materials can cause changes to bandwidth, effective masses, degeneracies and even structural phases. In the case of the transition metal dichalcogenide (TMD) semiconductors, small strain (around 1 percent) is expected to change band gaps and mobilities, while larger strains are expected to cause phase changes from the triangular 2H phase to orthorhombic 1T' phases. We will describe experimental techniques to apply small and large (around 10 percent) strains to one or few layer samples of the TMD semiconductors, and describe the effect of the strain using optical (Raman, photoluminescence) and cryogenic transport techniques.

  13. Stress-strain properties of railway steel at strain rates of upto 105 per second

    This paper presents the stress-strain characteristics of railway steel at strain rates of up to 105/s at room temperature determined by a new technique. In determining the results, account has been taken of the strain-rate variation, the total strain and the strain rate history. The effect of friction, material inertia and temperature rise is also assessed and an empirical constitutive equation describing the strain-rate and strain sensitive flow stress for this type of steel is proposed. (orig.)

  14. Comparison between strain values of plates measured by ESPI technique and strain gauge method

    Comparison between strain values of plates measured by Electronic Speckle Pattern Interferometry(ESPI) method and strain gauge method is discussed. Unlike traditional method, such ax strain gauge and moire method, ESPI method requires no special surface preparations or attachments and can be measured in-plane displacement with non-contacting in real-time. In this study, specimens are loaded in parallel using tensile testing machine. In front of a specimen three strain gauges are bonded with 5 mm gap from edge of a specimen strain values are measured at each strain gauge position and compared. The results by ESPI method agree well with the result by strain gauge method.

  15. Strain flexibility identification of bridges from long-gauge strain measurements

    Zhang, Jian; Xia, Qi; Cheng, YuYao; Wu, ZhiShen

    2015-10-01

    Strain flexibility, defined as the strain response of a structure's element to a unit input force, is import for structural safety evaluation, but its identification is seldom investigated. A novel long-gauge fiber optic sensor has been developed to measure the averaged strain within a long gauge length. Its advantage of measuring both local and global information of the structure offers an excellent opportunity of developing the strain flexibility identification theory. In this article, the method to identify structural strain flexibility from long-gauge dynamic strain measurements is proposed. It includes the following main steps: (a) macro strain frequency response function (FRF) estimation from macro strain measurements and its feature characterization; (b) general strain modal parameter identification; (c) scaling factor calculation, and (d) strain flexibility identification. Numerical and experimental examples successfully verify the effectiveness of the proposed method.

  16. Numerical demonstration of MEMS strain sensor

    Saboonchi, Hossain; Ozevin, Didem

    2012-04-01

    Silicon has piezoresistive property that allows designing strain sensor with higher gauge factor compared to conventional metal foil gauges. The sensing element can be micro-scale using MEMS, which minimizes the effect of strain gradient on measurement at stress concentration regions such as crack tips. The challenge of MEMS based strain sensor design is to decouple the sensing element from substrate for true strain measurement and to compensate the temperature effect on the piezoresistive coefficients of silicon. In this paper, a family of MEMS strain sensors with different geometric designs is introduced. Each strain sensor is made of single crystal silicon and manufactured using deposition/ etching/oxidation steps on a n- doped silicon wafer in (100) plane. The geometries include sensing element connected to the free heads of U shape substrate, a set of two or more sensing elements in an array in order to capture strain gradients and two directional sensors. The response function and the gauge factor of the strain sensors are identified using multi-physics models that combine structural and electrical behaviors of sensors mounted on a strained structure. The relationship between surface strain and strain at microstructure is identified numerically in order to include the relationship in the response function calculation.

  17. Strain engineering of graphene: a review

    Si, Chen; Sun, Zhimei; Liu, Feng

    2016-02-01

    Graphene has intrigued the science community by many unique properties not found in conventional materials. In particular, it is the strongest two-dimensional material ever measured, being able to sustain reversible tensile elastic strain larger than 20%, which yields an interesting possibility to tune the properties of graphene by strain and thus opens a new field called ``straintronics''. In this article, the current progress in the strain engineering of graphene is reviewed. We first summarize the strain effects on the electronic structure and Raman spectra of graphene. We then highlight the electron-phonon coupling greatly enhanced by the biaxial strain and the strong pseudomagnetic field induced by the non-uniform strain with specific distribution. Finally, the potential application of strain-engineering in the self-assembly of foreign atoms on the graphene surface is also discussed. Given the short history of graphene straintronics research, the current progress has been notable, and many further advances in this field are expected.

  18. Strain gauges as intrusion detection sensors

    Strain gauges have been studied for use as intrusion detection sensors in several applications being investigated at Sandia National Laboratories. Strain gauges are attached to a metal structure to monitor the quiescent strain in the structure. The change in the quiescent strain, when an intruder adds weight to the structure provides the alarm mechanism. The basic theory of force sensors is covered to lay the foundation for this application. In this paper, how this basic theory is applied to security sensors is discussed, and how this class of sensors is applicable to security at Department of Energy facilities is covered. Several applications are described for strain gauges as security sensors. Test results are presented from a six-month test conducted at a Department of Energy facility using the strain gauge to monitor overhead lines crossing a security perimeter. Monitoring these overhead lines with strain gauges is valuable because the cost is much less than the cost to bury the lines

  19. Generalizing the Fermi velocity of strained graphene from uniform to nonuniform strain

    Oliva-Leyva, M.; Naumis, Gerardo G.

    2014-01-01

    The relevance of the strain-induced Dirac point shift to obtain the appropriate anisotropic Fermi velocity of strained graphene is demonstrated. Then a critical revision of the available effective Dirac Hamiltonians is made by studying in detail the limiting case of a uniform strain. An effective Dirac Hamiltonian for nonuniform strain is thus reported, which takes into account all strain-induced effects: changes in the nearest-neighbor hopping parameters, the reciprocal lattice deformation a...

  20. A Method to Measure Reference Strain in FBG Strain Sensor Interrogation System Involving Actuators

    Rajan, Ginu; Semenova, Yuliya; Wu, Qiang; Farrell, Gerald; Wang, Pengfei

    2007-01-01

    A method for reference strain measurement for FBG strain sensor in the testing stage while applying strain using actuators like piezo translators or micro screw is introduced. Unlike conventional methods of surface mounting, in our method the strain gauge is affixed directly to the optical fibre, which allows it to use with systems where the strain is applied directly using actuators while testing the FBG sensing system. Different bonding techniques were tested and a comparison with the resul...

  1. Application of capsule type strain gage and fiber optic grating strain sensor for measurement of strain under irradiation environment

    In Japan Atomic Energy Research Institute, in-pile strain measurement techniques have been developing by using JMTR. In order to evaluate the performance of capsule type strain gage and fiber optic grating sensor under irradiation environment, the heat-up tests in electric furnace before irradiation and in-pile tests were performed. As for capsule type strain gage, it is found that gage factor almost did not change and both its electric resistance and strain output decreased by irradiation effect. A correlation was found between the change ratio of the electric resistance of the capsule type strain gage and fast neutron fluence. As for fiber optic grating sensor, it is possible to measure strain under irradiation environment below 1x1023 n/m2 (E>1 MeV) by this sensor, because in-pile temperature characteristic was in agreement with out-of-pile test results. (author)

  2. Modeling competition between yeast strains

    de Gee, Maarten; van Mourik, Hilda; de Visser, Arjan; Molenaar, Jaap

    2016-04-01

    We investigate toxin interference competition between S. cerevisiae colonies grown on a solid medium. In vivo experiments show that the outcome of this competition depends strongly on nutrient availability and cell densities. Here we present a new model for S. cerevisiae colonies, calculating the local height and composition of the colonies. The model simulates yeast colonies that show a good fit to experimental data. Simulations of colonies that start out with a homogeneous mixture of toxin producing and toxin sensitive cells can display remarkable pattern formation, depending on the initial ratio of the strains. Simulations in which the toxin producing and toxin sensitive species start at nearby positions clearly show that toxin production is advantageous.

  3. Investigation of Electronic Devices for Strain Measurement

    Ričardas Masiulionis

    2011-08-01

    Full Text Available Importance of strain measuring for safety of buildings is shown. The strain monitoring should be one of the buildings security systems. Often used balanced and non-balanced Wheatstone bridge strain measurement methods are analyzed. The Wheatstone bridge method with feedback is improved. A new method based on small resistance changes by the digital balancing currents is presented. Computer and experimental models of measurement are investigated. The received results confirm theoretical assumptions.Article in Lithuanian

  4. Mechanical strain and degradation of laser heterostructures

    Ptashchenko, Alexander A.; Ptashchenko, Fedor A.; Maslejeva, Natalia V.; Sadova, Galina V.

    2001-02-01

    The effect of mechanical strain on degradation processes in GaAs-AlGaAs laser heterostructures (LHS) with stripe geometry and in light emitting diodes (LED) was experimentally studied. The strain was produced either by axial pressure or by indentation with a Wickers pyramid. We show that degradation affects the degree of polarization and the far-field distribution of laser emission. The effect of strain on the degradation intensity is estimated.

  5. Aggregation and distribution of strains in microparasites.

    Lord, C. C.; Barnard, B.; Day, K; Hargrove, J. W.; McNamara, J J; Paul, R E; Trenholme, K; Woolhouse, M. E.

    1999-01-01

    Recent research has shown that many parasite populations are made up of a number of epidemiologically distinct strains or genotypes. The implications of strain structure or genetic diversity for parasite population dynamics are still uncertain, partly because there is no coherent framework for the interpretation of field data. Here, we present an analysis of four published data sets for vector-borne microparasite infections where strains or genotypes have been distinguished: serotypes of Afri...

  6. Flat band superconductivity in strained Dirac materials

    Kauppila, V. J.; Aikebaier, F.; Heikkilä, T. T.

    2016-01-01

    We consider superconducting properties of a two-dimensional Dirac material such as graphene under strain that produces a flat band spectrum in the normal state. We show that in the superconducting state, such a model results in a highly increased critical temperature compared to the case without the strain, inhomogenous order parameter with two-peak shaped local density of states and yet a large and almost uniform and isotropic supercurrent. This model could be realized in strained graphene o...

  7. Strain rate sensitivity of automotive sheet steels : influence of plastic strain, strain rate, temperature, microstructure, bake hardening and pre-strain

    Larour, Patrick

    2010-01-01

    This experimental work shows the different parameters influencing the strain rate sensitivity behaviour of automotive sheet steel grades in crash conditions. Most investigations have been performed in the strain rate range [0,001-200/s] and temperature range [233-373K] with servohydraulic tensile testing machines. Additional Split-Hopkinson bar testing results up to 1000/s have also been included at room temperature. The focus has been laid on the “apparent” strain rate sensitivity, determine...

  8. Nonlinear strain gradient elastic thin shallow shells

    Lazopoulos, K.A.

    2011-01-01

    Abstract The governing equilibrium equations for strain gradient elastic thin shallow shells are derived, considering non-linear strains and linear constitutive strain gradient elastic relations. Adopting Kirchhoff's theory of thin shallow structures, the equilibrium equations, along with the boundary conditions, are formulated through a variational procedure. It turns out that new terms are introduced, indicating the importance of the cross-section area in bending of thin plates. ...

  9. High strain rate loading of zircaloy

    High strain rate tensile loading behaviours of Zircaloys subjected to various treatments were investigated at room temperature and at 3000C, and compared with those of static cases. It was observed that the dynamic stress-strain profiles were different depending upon the specimen treatment and that the higher peak stress and the lower sectional area reduction were always recognized in the high strain rate cases

  10. Film germanium strain gauges for cryogenic temperatures

    Strain-measuring characteristics of strain gauges (SG) based on germanium films on gallium arsenide designed for operation in 4-100 K temperature interval and strain range ε∼(±0.3%) are presented. SG are characterized by weak temperature dependences of resistance and strain sensitivity in the temperature range measured. It is shown that in the low-temperature region SG based on heteroepitaxial germanium films on gallium arsenide are no worse than the best domestic and foreign semiconducting and metal SG and are perspective for cryogenic object diagnostics under magnetic field effect

  11. High strain rate damage of Carrara marble

    Doan, Mai-Linh; Billi, Andrea

    2011-10-01

    Several cases of rock pulverization have been observed along major active faults in granite and other crystalline rocks. They have been interpreted as due to coseismic pervasive microfracturing. In contrast, little is known about pulverization in carbonates. With the aim of understanding carbonate pulverization, we investigate the high strain rate (c. 100 s-1) behavior of unconfined Carrara marble through a set of experiments with a Split Hopkinson Pressure Bar. Three final states were observed: (1) at low strain, the sample is kept intact, without apparent macrofractures; (2) failure is localized along a few fractures once stress is larger than 100 MPa, corresponding to a strain of 0.65%; (3) above 1.3% strain, the sample is pulverized. Contrary to granite, the transition to pulverization is controlled by strain rather than strain rate. Yet, at low strain rate, a sample from the same marble displayed only a few fractures. This suggests that the experiments were done above the strain rate transition to pulverization. Marble seems easier to pulverize than granite. This creates a paradox: finely pulverized rocks should be prevalent along any high strain zone near faults through carbonates, but this is not what is observed. A few alternatives are proposed to solve this paradox.

  12. Comparison of Thermal Creep Strain Calculation Results Using Time Hardening and Strain Hardening Rules

    One of the design criteria for the fuel rod in PGSFR is the thermal creep strain of the cladding, because the cladding is exposed to a high temperature for a long time during reactor operation period. In general, there are two kind of calculation scheme for thermal creep strain: time hardening and strain hardening rules. In this work, thermal creep strain calculation results for HT9 cladding by using time hardening and strain hardening rules are compared by employing KAERI's current metallic fuel performance analysis code, MACSIS. Also, thermal creep strain calculation results by using ANL's metallic fuel performance analysis code, LIFE-METAL which adopts strain hardening rule are compared with those by using MACSIS. Thermal creep strain calculation results for HT9 cladding by using time hardening and strain hardening rules were compared by employing KAERI's current metallic fuel performance analysis code, MACSIS. Also, thermal creep strain calculation results by using ANL's metallic fuel performance analysis code, LIFE-METAL which adopts strain hardening rule were compared with those by using MACSIS. Tertiary creep started earlier in time hardening rule than in strain hardening rule. Also, calculation results by MACSIS with strain hardening and those obtained by using LIFE-METAL were almost identical to each other

  13. The treatment of secondary strains within a strain-based failure assessment diagram

    In a companion paper, proposals for the shape of a strain-based failure assessment diagram (FAD) have been made. The developments in that paper and in related works on strain-based fracture assessment have largely been for remotely applied strains, such as those produced by welding. This paper re-writes existing methods for treating secondary stresses within stress-based FADs in the framework of the proposed strain-based FAD. It is shown that residual strains must be included fully in the elastic regime but at large applied strains their contribution to fracture can be relaxed considerably. Practical methods for inclusion of secondary strains within the strain-based FAD are then developed and shown to be conservative relative to some detailed finite element calculations. -- Highlights: ► Methods for treating secondary stresses are written in the framework of a strain-based FAD. ► Residual strains have a full effect in the elastic regime but their influence is relaxed considerably at large applied strains. ► Practical methods for inclusion of secondary strains within a strain-based FAD are developed. ► The methods are shown to be conservative relative to some detailed finite element calculations

  14. True stress–strain curves of cold worked stainless steel over a large range of strains

    True stress–strain curves for cold worked stainless steel were obtained over a range of strains that included a large strain exceeding the strain for the tensile strength (post-necking strain). A specified testing method was used to obtain the stress–strain curves in air at room temperature. The testing method employed the digital image correlation (DIC) technique and iterative finite element analyses (FEA) and was referred to as IFD (Iteration FEA procedure based on DIC measurement) method. Although hourglass type specimens have been previously used for the IFD method, in this study, plate specimens with a parallel gage section were used to obtain accurate yield and tensile strengths together with the stress–strain curves. The stress–strain curves including the post-necking strain were successfully obtained by the IFD method, and it was shown that the stress–strain curves for different degrees of cold work collapsed onto a single curve when the offset strain was considered. It was also shown that the Swift type constitutive equation gave good regression for the true stress–strain curves including the post-necking strain regardless of the degree of cold work, although the Ramberg–Osgood type constitutive equation showed poor fit. In the regression for the Swift type constitutive equation, the constant for power law could be assumed to be nS = 0.5

  15. A comparison of eastern North American seismic strain-rates to glacial rebound strain-rates

    James, Thomas S.; Bent, Allison L.

    1994-01-01

    Glacial rebound strain-rates computed using a simple Laurentide glacial loading model are of the order of 10(exp -9) per year within the region of glaciation and extending several hundred kilometers beyond. The horizontal strain-rates receive approximately equal contributions from horizontal and vertical velocities, a consequence of the spherical geometry adopted for the Earth model. In the eastern United States and southeastern Canada the computed strain-rates are 1-3 orders of magnitude greater than an estimate of the average seismic strain-rate (Anderson, 1986) and approximately 1 order of magnitude greater than predicted erosional strain-rates. The predicted glacial rebound strain-rates are not, in general, oriented in such a way as to augment the observed state of deviatoric stress, possibly explaining why the seismic strain-rates are much smaller than the glacial rebound strain-rates. An exception to this may be seismically active regions in the St. Lawrence valley.

  16. Predicting creep rupture from early strain data

    To extend creep life modelling from classical rupture modelling, a robust and effective parametric strain model has been developed. The model can reproduce with good accuracy all parts of the creep curve, economically utilising the available rupture models. The resulting combined model can also be used to predict rupture from the available strain data, and to further improve the rupture models. The methodology can utilise unfailed specimen data for life assessment at lower stress levels than what is possible from rupture data alone. Master curves for creep strain and rupture have been produced for oxygen-free phosphorus-doped (OFP) copper with a maximum testing time of 51,000 h. Values of time to specific strain at given stress (40-165 MPa) and temperature (125-350 deg. C) were fitted to the models in the strain range of 0.1-38%. With typical inhomogeneous multi-batch creep data, the combined strain and rupture modelling involves the steps of investigation of the data quality, extraction of elastic and creep strain response, rupture modelling, data set balancing and creep strain modelling. Finally, the master curves for strain and rupture are tested and validated for overall fitting efficiency. With the Wilshire equation as the basis for the rupture model, the strain model applies classical parametric principles with an Arrhenius type of thermal activation and a power law type of stress dependence for the strain rate. The strain model also assumes that the processes of primary and secondary creep can be reasonably correlated. The rupture model represents a clear improvement over previous models in the range of the test data. The creep strain information from interrupted and running tests were assessed together with the rupture data investigating the possibility of rupture model improvement towards lower stress levels by inverse utilisation of the combined rupture based strain model. The developed creep strain model together with the improved rupture model is

  17. The Stress-Strain Condition Estimation of Detail in Crack Tip by Integral Strain Gauges

    Syzrantsev, V.; Syzrantseva, K.

    2016-04-01

    The paper considers the task of stress-strain condition calculation of experimental sample in fatigue crack tip on weld boundary at its cyclic deforming. For this task decision authors use the information obtained by original means of cyclic strains measurement: Integral Strain Gauges. The results of carried experimental researches are compared with data of stress-strain condition estimation of detail in crack tip calculated by Finish Element Method.

  18. Effect of strain rate and temperature at high strains on fatigue behavior of SAP alloys

    Blucher, J.T.; Knudsen, Per; Grant, N.J.

    1968-01-01

    Fatigue behavior of three SAP alloys of two nominal compositions (7 and 13% Al2O3) was studied in terms of strain rate and temperature at high strains; strain rate had no effect on life at 80 F, but had increasingly greater effect with increasing temperature above 500 F; life decreased with...... decreasing strain rate, above 500 F, and with increasing temperature; ductility at fracture in tension test is shown to be important factor in determining life under conditions of test. (20318)...

  19. Multiplying decomposition of stress/strain, constitutive/compliance relations, and strain energy

    Lee, Hyunsuk; Kim, Jinkyu

    2012-01-01

    To account for phenomenological theories and a set of invariants, stress and strain are usually decomposed into a pair of pressure and deviatoric stress and a pair of volumetric strain and deviatoric strain. However, the conventional decomposition method only focuses on individual stress and strain, so that cannot be directly applied to either formulation in Finite Element Method (FEM) or Boundary Element Method (BEM). In this paper, a simpler, more general, and widely applicable decompositio...

  20. Influence of Azospirillum Strains on the Nodulation of Clovers by Rhizobium Strains

    Plazinski, Jacek; Rolfe, Barry G.

    1985-01-01

    Mixed cultures of several Azospirillum and Rhizobium trifolii strains caused either an inhibition or stimulation of nodule formation on plant hosts as compared with nodulation of plants inoculated with R. trifolii alone. Azospirillum strains affected the nodulation process at a precise cell ratio (R. trifolii/Azospirillum cells) and time of inoculation. All Azospirillum strains used showed a variation in their ability to inhibit or enhance nodulation by R. trifolii strains. When nonviable cel...

  1. Crack growth monitoring by strain measurements

    Cracks detected during in-service inspections are not always removed when they are judged as hazardous. It is important to monitor the crack growth in order to secure the integrity of the cracked components. The author and a co-worker proposed a crack growth monitoring method, in which the elastic strain caused by internal pressure is continuously measured. The elastic strain acting at the outside surface of a pressurized pipe changes due to growth of a crack in the inside surface, and the magnitude of its change depends on the growth size. In this study, the author uses multiple strain gages to monitor the elastic strain acting on the cracked part of a pipe. An axial crack was introduced at the butt welding portion inside a carbon steel pipe. The strains were then measured under static internal pressure. The crack size was estimated based on the change in strains measured by strain gages attached onto the outside surface of the pipe. This study reveals that such a monitoring procedure could successfully identify not only the crack depth but also the surface length. The maximum estimation errors were 2.2 mm and 0.97 mm for the surface length and depth, respectively. The accuracy of the estimation improved as the number of strain gages increased. It was also apparent that the residual stress had subtle effect on the size estimation, albeit it may have significant influence when the crack propagates. (author)

  2. On lower order strain gradient plasticity theories

    Niordson, Christian Frithiof; Hutchinson, J. W.

    2002-01-01

    By way of numerical examples, this paper explores the nature of solutions to a class of strain gradient plasticity theories that employ conventional stresses, equilibrium equations and boundary conditions. Strain gradients come into play in these modified conventional theories only to alter the...

  3. On lower order strain gradient plasticity theories

    Niordson, Christian Frithiof; Hutchinson, J. W.

    2003-01-01

    By way of numerical examples, this paper explores the nature of solutions to a class of strain gradient plasticity theories that employ conventional stresses, equilibrium equations and boundary conditions. Strain gradients come into play in these modified conventional theories only to alter the...

  4. Nanocomposite Strain Gauges Having Small TCRs

    Gregory, Otto; Chen, Ximing

    2009-01-01

    Ceramic strain gauges in which the strain-sensitive electrically conductive strips made from nanocomposites of noble metal and indium tin oxide (ITO) are being developed for use in gas turbine engines and other power-generation systems in which gas temperatures can exceed 1,500 F (about 816 C). In general, strain gauges exhibit spurious thermally induced components of response denoted apparent strain. When temperature varies, a strain-gauge material that has a nonzero temperature coefficient of resistance (TCR) exhibits an undesired change in electrical resistance that can be mistaken for the change in resistance caused by a change in strain. It would be desirable to formulate straingauge materials having TCRs as small as possible so as to minimize apparent strain. Most metals exhibit positive TCRs, while most semiconductors, including ITO, exhibit negative TCRs. The present development is based on the idea of using the negative TCR of ITO to counter the positive TCRs of noble metals and of obtaining the benefit of the ability of both ITO and noble metals to endure high temperatures. The noble metal used in this development thus far has been platinum. Combinatorial libraries of many ceramic strain gauges containing nanocomposites of various proportions of ITO and platinum were fabricated by reactive co-sputtering from ITO and platinum targets onto alumina- and zirconia-based substrates mounted at various positions between the targets.

  5. High-Temperature Resistance Strain Gauges

    Lei, Jih-Fen

    1994-01-01

    Resistance strain gauges developed for use at high temperatures in demanding applications like testing aircraft engines and structures. Measures static strains at temperatures up to 800 degrees C. Small and highly reproducible. Readings corrected for temperature within small tolerances, provided temperatures measured simultaneously by thermocouples or other suitable devices. Connected in wheatstone bridge.

  6. Whole genome sequences of four Brucella strains.

    Ding, Jiabo; Pan, Yuanlong; Jiang, Hai; Cheng, Junsheng; Liu, Taotao; Qin, Nan; Yang, Yi; Cui, Buyun; Chen, Chen; Liu, Cuihua; Mao, Kairong; Zhu, Baoli

    2011-07-01

    Brucella melitensis and Brucella suis are intracellular pathogens of livestock and humans. Here we report four genome sequences, those of the virulent strain B. melitensis M28-12 and vaccine strains B. melitensis M5 and M111 and B. suis S2, which show different virulences and pathogenicities, which will help to design a more effective brucellosis vaccine. PMID:21602346

  7. Job strain and time to pregnancy

    Hjollund, N H; Jensen, Tina Kold; Bonde, J P; Henriksen, T B; Kolstad, H A; Andersson, A M; Ernst, E; Giwercman, A; Skakkebaek, N E; Olsen, J

    1998-01-01

    The association between fertility and job strain defined as high job demands and low job control has not previously been studied. A follow-up study was conducted with prospective collection of information on job strain among women, achievement of pregnancy, and potential confounding variables....

  8. Marital Role Strain and Sexual Satisfaction.

    Frank, Ellen; And Others

    1979-01-01

    Responses to a questionnaire pertaining to discrepancies between an individual's ideal and actual marital role behaviors and level of sexual satisfaction indicated lower levels of role strain in nonpatient couples. A higher level of role strain correlated with increased sexual dissatisfaction. (Author)

  9. A Natural Vaccine Candidate Strain Against Cholera

    LIUYAN-QING; QIGUO-MING; 等

    1995-01-01

    El Tor Vibrio cholerae(EVC)strains may be classified into two kinds-epidemigenic(EEVC)strains and non-epidemigenic(NEEVC)strains-based on a phage-biotyping system.A large number of EEVC strains have been screened for toxigenic and putative colonization attributes.One such naturally occurring strain(designated IEM101)has been found which is devoid of genes encoding cholera toxin(CT),accessory cholera enterotoxin(ACE),zonula occludens toxin(ZOT),but possesses RS1 sequences and toixn-coregulated pilus A gene(tcpA)although tcpA is poorly expressed.It expresses type B pili but does not posses type C pili.It is an El Tor Ogawa strain and does not cause fluid accumulation in rabbit ileal loop tests.Active immunization of rabbits with strain IEM101 elicited good protection against challenge with virulent strains of V.cholerae Ol.Oral administration cased no side effects in 15 human volunteers.colonized the gut for four to ten days and elicited good immune responses.

  10. On fracture in finite strain gradient plasticity

    Martínez Pañeda, Emilio; Niordson, Christian Frithiof

    2016-01-01

    In this work a general framework for damage and fracture assessment including the effect of strain gradients is provided. Both mechanism-based and phenomenological strain gradient plasticity (SGP) theories are implemented numerically using finite deformation theory and crack tip fields are...... investigated. Differences and similarities between the two approaches within continuum SGP modeling are highlighted and discussed. Local strain hardening promoted by geometrically necessary dislocations (GNDs) in the vicinity of the crack leads to much higher stresses, relative to classical plasticity...... predictions. These differences increase significantly when large strains are taken into account, as a consequence of the contribution of strain gradients to the work hardening of the material. The magnitude of stress elevation at the crack tip and the distance ahead of the crack where GNDs significantly alter...

  11. Mechanical strain effects on black phosphorus nanoresonators.

    Wang, Cui-Xia; Zhang, Chao; Jiang, Jin-Wu; Park, Harold S; Rabczuk, Timon

    2016-01-14

    We perform classical molecular dynamics simulations to investigate the effects of mechanical strain on single-layer black phosphorus nanoresonators at different temperatures. We find that the resonant frequency is highly anisotropic in black phosphorus due to its intrinsic puckered configuration, and that the quality factor in the armchair direction is higher than in the zigzag direction at room temperature. The quality factors are also found to be intrinsically larger than those in graphene and MoS2 nanoresonators. The quality factors can be increased by more than a factor of two by applying tensile strain, with uniaxial strain in the armchair direction being the most effective. However, there is an upper bound for the quality factor increase due to nonlinear effects at large strains, after which the quality factor decreases. The tension induced nonlinear effect is stronger along the zigzag direction, resulting in a smaller maximum strain for quality factor enhancement. PMID:26649476

  12. Dark field electron holography for strain measurement

    Dark field electron holography is a new TEM-based technique for measuring strain with nanometer scale resolution. Here we present the procedure to align a transmission electron microscope and obtain dark field holograms as well as the theoretical background necessary to reconstruct strain maps from holograms. A series of experimental parameters such as biprism voltage, sample thickness, exposure time, tilt angle and choice of diffracted beam are then investigated on a silicon-germanium layer epitaxially embedded in a silicon matrix in order to obtain optimal dark field holograms over a large field of view with good spatial resolution and strain sensitivity. -- Research Highlights: → Step by step explanation of the dark field electron holography technique. → Presentation of the theoretical equations to obtain quantitative strain map. → Description of experimental parameters influencing dark field holography results. → Quantitative strain measurement on a SiGe layer embedded in a silicon matrix.

  13. Pseudomagnetic fields and triaxial strain in graphene

    Settnes, Mikkel; Power, Stephen; Jauho, Antti-Pekka

    2016-01-01

    Pseudomagnetic fields, which can result from nonuniform strain distributions, have received much attention in graphene systems due to the possibility of mimicking real magnetic fields with magnitudes of greater than 100 T. We examine systems with such strains confined to finite regions ("pseudoma......Pseudomagnetic fields, which can result from nonuniform strain distributions, have received much attention in graphene systems due to the possibility of mimicking real magnetic fields with magnitudes of greater than 100 T. We examine systems with such strains confined to finite regions......-binding calculations of single pseudomagnetic dots in extended graphene sheets confirm these predictions, and are also used to study the effect of rotating the strain direction with respect to the underlying graphene lattice, and varying the size of the pseudomagnetic dot....

  14. Review of graphene-based strain sensors

    Zhao Jing; Zhang Guang-Yu; Shi Dong-Xia

    2013-01-01

    In this paper,we review various types of graphene-based strain sensors.Graphene is a monolayer of carbon atoms,which exhibits prominent electrical and mechanical properties and can be a good candidate in compact strain sensor applications.However,a perfect graphene is robust and has a low piezoresistive sensitivity.So scientists have been driven to increase the sensitivity using different kinds of methods since the first graphene-based strain sensor was reported.We give a comprehensive review of graphene-based strain sensors with different structures and mechanisms.It is obvious that graphene offers some advantages and has potential for the strain sensor application in the near future.

  15. Dark field electron holography for strain measurement

    Beche, A., E-mail: armand.beche@fei.com [CEA-Grenoble, INAC/SP2M/LEMMA, F-38054 Grenoble (France); Rouviere, J.L. [CEA-Grenoble, INAC/SP2M/LEMMA, F-38054 Grenoble (France); Barnes, J.P.; Cooper, D. [CEA-LETI, Minatec Campus, F-38054 Grenoble (France)

    2011-02-15

    Dark field electron holography is a new TEM-based technique for measuring strain with nanometer scale resolution. Here we present the procedure to align a transmission electron microscope and obtain dark field holograms as well as the theoretical background necessary to reconstruct strain maps from holograms. A series of experimental parameters such as biprism voltage, sample thickness, exposure time, tilt angle and choice of diffracted beam are then investigated on a silicon-germanium layer epitaxially embedded in a silicon matrix in order to obtain optimal dark field holograms over a large field of view with good spatial resolution and strain sensitivity. -- Research Highlights: {yields} Step by step explanation of the dark field electron holography technique. {yields} Presentation of the theoretical equations to obtain quantitative strain map. {yields} Description of experimental parameters influencing dark field holography results. {yields} Quantitative strain measurement on a SiGe layer embedded in a silicon matrix.

  16. Near tip strain evolution under cyclic loading

    J. Tong

    2013-07-01

    Full Text Available The concept of ratchetting strain as a crack driving force in controlling crack growth has previously been explored at Portsmouth using numerical approaches for nickel-based superalloys. In this paper, we report the first experimental observations of the near-tip strain evolution as captured by the Digital Image Correlation (DIC technique on a compact tension specimen of stainless steel 316L. The evolution of the near-tip strains with loading cycles was studied whilst the crack tip was maintained stationary. The strains were monitored over the selected distances from the crack tip for a given number of cycles under an incremental loading regime. The results show that strain ratchetting does occur with load cycling, and is particularly evident close to the crack tip and under higher loads. A finite element model has been developed to simulate the experiments and the simulation results are compared with the DIC measurements.

  17. Microstructure and strain hardening of steels

    In the present work, the relation between metallurgical microstructures and strain hardening behaviour of both fcc and bcc steels was investigated. In order to obtain large strains, a new experimental method was developed and the data mathematically prepared for further analysis. It was found that the strain hardening rate increases with decreasing particle size or increasing yield stress of ferritic steels. The strain hardening rate is found to be correlated to the specific microstructure. A new model was formulated to describe large deformations. This has been done on the basis of already existing models. According to the new model, the strain hardening in stage IV is caused by the dislocations in cell interiors instead of those in the cell walls. (orig.)

  18. Nanoscale strain mapping in battery nanostructures

    Ulvestad, A., E-mail: aulvesta@ucsd.edu; Kim, J. W.; Dietze, S. H.; Shpyrko, O. G. [Department of Physics, University of California-San Diego, La Jolla, California 92093-0319 (United States); Cho, H. M.; Meng, Y. S. [Department of NanoEngineering, University of California-San Diego, La Jolla, California 92093-0448 (United States); Harder, R. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Fohtung, E. [Manuel Lujan Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Department of Physics, New Mexico State University, Las Cruces, New Mexico 88003 (United States)

    2014-02-17

    Coherent x-ray diffraction imaging is used to map the local three dimensional strain inhomogeneity and electron density distribution of two individual LiNi{sub 0.5}Mn{sub 1.5}O{sub 4−δ} cathode nanoparticles in both ex-situ and in-situ environments. Our reconstructed images revealed a maximum strain of 0.4%. We observed different variations in strain inhomogeneity due to multiple competing effects. The compressive/tensile component of the strain is connected to the local lithium content and, on the surface, interpreted in terms of a local Jahn-Teller distortion of Mn{sup 3+}. Finally, the measured strain distributions are discussed in terms of their impact on competing theoretical models of the lithiation process.

  19. Irreducible decomposition of strain gradient tensor in isotropic strain gradient elasticity

    Lazar, Markus

    2016-01-01

    In isotropic strain gradient elasticity, we decompose the strain gradient tensor into its irreducible pieces under the n-dimensional orthogonal group O(n). Using the Young tableau method for traceless tensors, four irreducible pieces (n>2), which are canonical, are obtained. In three dimensions, the strain gradient tensor can be decomposed into four irreducible pieces with 7+5+3+3 independent components whereas in two dimensions, the strain gradient tensor can be decomposed into three irreducible pieces with 2+2+2 independent components. The knowledge of these irreducible pieces is extremely useful when setting up constitutive relations and strain energy.

  20. Strain relaxation in nano-patterned strained-Si/SiGe heterostructure on insulator

    In order to evaluate the strain stability, arrays of strained Si/SiGe nano-stripes and nano-pillars were fabricated by Electron-Beam Lithography (EBL) and Reactive-Ion Etching (RIE). The strain relaxation in the patterned strained Si on SiGe-on-insulator (SGOI) was investigated by high-resolution UV micro-Raman spectroscopy. The Raman measurements before and after patterning indicate that most of the strain in the top strained Si is maintained until scaling down to 300 nm, and relaxation of <15% is observed in pillars with a dimension of 150 nm x 150 nm. In the nano-patterned heterostructure strained Si/SiGe, the observed relaxation is small, which is mainly attributed to the fully relaxed and dislocation-free SiGe virtual substrate fabricated by modified Ge condensation.

  1. Strain mapping analysis of textile composites

    Ivanov, Dmitry; Ivanov, Sergey; Lomov, Stepan; Verpoest, Ignaas

    2009-03-01

    The focus of the work is meso-scale analysis (scale level of the fabric unit cell) of textile composite deformation and failure. The surface strain measurement is used for: (1) experimental investigation, which includes study of strain distribution at various stages of deformation, plasticity detection, damage initiation; (2) numerical validation of the correspondent finite element (FE) models. Two examples are considered: carbon-epoxy triaxial-braided and glass polypropylene-woven composite. The surface strain measurement (by digital image correlation technique) accompanies the tensile tests, aiming at: (1) elastic anisotropic constants characterisation, (2) study of non-linear material behaviour (for the thermoplastic composite), (3) control of homogeneity of the macro-strain distribution, and (4) analysis of damage initiation in brittle composites. Validation of meso-FE models by strain measurements encounters difficulties arising from (1) resolution of the strain measurements, (2) irregularities of the initial structure such as random layer nesting, ply interaction, and deviation of yarns from their theoretical position, which affects the measured strain fields. The paper discusses these difficulties and demonstrates a qualitative agreement with the FE analysis of idealised composite configurations.

  2. Thermoresistance in radioresistant strains of 'Drosophila nebulosa'

    The detection of thermoresistance in radioresistant strains of 'D. nebulosa' is described, as well as some conclusions on the genetic nature of these differences are presented. The strains used in this experiment were MF 204, from 'Morro de Ferro', in Pocos de Caldas (MG) (one of the biggest radioactive anomalies in the world) whose radioresistance is due to its additive genetic components (Kratz, 1973 and 1975); 85(87) R, an induced radioresistant strain; and MF K a control 'pooled' strain obtained near 'Morro do Ferro'. Survival tests, 72 hours after temperature shocks, performed in the interval of 360C to 390C showed a decreasing gradient of thermoresistance with the following regression coefficients: MF 204 b=-5,4; 85(87)R b=-7,2 and MF K b=-7,9. Bifactorial analysis (strains and sexes) performed at 380C and 390C confirmed differences among strains (P<01 and P<0,5, respectively) suggesting a poligenic control of the thermoresistance. Consitent and verified relations among strains, being simultaneously resistant to different kinds of mutagenic factors, are considered evidence of the existence of general mechanisms in mutagenic control. Therefore, the results, together with results of Tsukamoto, Ogaki and Kikkawa 1957, Ogaki 1962 and Nakashima-Tanaka 1966, Parsons 1969, add to the hypotheses of the existence of general mechanisms in mutagenic control

  3. Piezoelectric strain sensor/actuator rosettes

    In-plane anisotropy in the linear piezoelectric constitutive law for [011]c cut and poled PMN–0.29PT is demonstrated to enable its use as a sensor/actuator rosette. The equations for a 0°/45°/90° rosette are developed using the conditions of coupling between the in-plane strain of the crystal and a substrate, and zero out-of-plane stress on the crystal (plane stress conditions in the crystals). The crystals are bonded to a substrate aluminum plate that is instrumented with strain gages next to the crystals. The plate is subjected to bending about different axes and the resulting electric displacement change of the crystals is monitored. The strain components calculated using the change of electric displacement are compared with the strain components measured using strain gages. This sensor/actuator rosette approach is demonstrated to enable both sensing principal strain components and actuating principal strains in an electronically controllable direction. (fast track communication)

  4. PHYLOGENETIC STUDY OF SOME STRAINS OF DUNALIELLA

    Duc Tran

    2013-01-01

    Full Text Available Dunaliella strains were isolated from a key site for salt production in Vietnam (Vinh Hao, Binh Thuan province. The strains were identified based on Internal Transcribed Spacer (ITS markers. The phylogenetic tree revealed these strains belong to the clades of Dunaliella salina and Dunaliella viridis. Results of this study confirm the ubiquitous nature of Dunaliella and suggest that strains of Dunaliella salina might be acquired locally worldwide for the production of beta-carotene. The identification of these species infers the presence of other Dunaliella species (Dunaliella tertiolecta, Dunaliella primolecta, Dunaliella parva, but further investigation would be required to confirm their presence in Vietnam. We anticipate the physiological and biochemical characteristics of these local species will be compared with imported strains in a future effort. This will facilitate selection of strains with the best potential for exploitation in the food, aquaculture and biofuel industries. The Dunaliella strains isolated and identified in this study are maintained at the Laboratory of Algal Biotechnology, International University and will be made available for research and educational institutions.

  5. Strain gradient plasticity: energetic or dissipative?

    Fleck, N. A.; Willis, J. R.

    2015-08-01

    For an infinite slab of strain gradient sensitive material subjected to plane-strain tensile loading, computation established and analysis confirmed that passivation of the lateral boundaries at some stage of loading inhibits plastic deformation upon further loading. This result is not surprising in itself except that, remarkably, if the gradient terms contribute to the dissipation, the plastic deformation is switched off completely and only resumes at a clearly defined higher load, corresponding to a total strain , say. The analysis presented in this paper confirms the delay of plastic deformation following passivation and determines the exact manner in which the plastic flow resumes. The plastic strain rate is continuous at the exact point of resumption of plastic flow and, for the first small increment in the imposed total strain, the corresponding increment in plastic strain, , is proportional to . The constant A in the relation , where denotes the plastic strain increment at the centre of the slab, has been determined explicitly; it depends on the hardening modulus of the material. The presence of energetic gradient terms has no effect on the value of unless the dissipative terms are absent, in which case passivation reduces the rate of plastic deformation but introduces no delay. This qualitative effect of dissipative gradient terms opens the possibility of experimental discrimination of their presence or absence. The analysis employs an incremental variational formulation that is likely to find use in other problems.

  6. Revisiting the gauge fields of strained graphene

    Iorio, Alfredo; Pais, Pablo(Centro de Estudios Científicos (CECS), Casilla, 1469 , Valdivia, Chile)

    2015-01-01

    We show that, when graphene is only subject to strain, the spin connection gauge field that arises plays no measurable role, but when intrinsic curvature is present and strain is small, spin connection dictates most the physics. We do so by showing that the Weyl field associated with strain is a pure gauge field and no constraint on the $(2+1)$-dimensional spacetime appears. On the other hand, for constant intrinsic curvature that also gives a pure-gauge Weyl field, we find a classical manife...

  7. STRAIN ANALYSIS OF LATERAL EXTRUSION PROCESS

    1999-01-01

    The strain distribution of equal-cross section lateral extrusion(ECSLE) has been simulated by finite element method. Considering the effect of friction and the width of sample, the simulation results are very close to the reality. The simulated results showed that, around the corner of die, the strain is distributed by sharp layers, and the gradient of the layers is very large, which means that the deformation is just plane shear deformation; the larger the width of sample or the smaller the friction, the more uniform the strain distribution is.

  8. Semiconductor strain metrology principles and applications

    Wong, Terence KS

    2012-01-01

    This book surveys the major and newly developed techniques for semiconductor strain metrology. Semiconductor strain metrology has emerged in recent years as a topic of great interest to researchers involved in thin film and nanoscale device characterization. This e-book employs a tutorial approach to explain the principles and applications of each technique specifically tailored for graduate students and postdoctoral researchers. Selected topics include optical, electron beam, ion beam and synchrotron x-ray techniques. Unlike earlier references, this e-book specifically discusses strain metrol

  9. Self-diffusion in compressively strained Ge

    Under a compressive biaxial strain of ∼ 0.71%, Ge self-diffusion has been measured using an isotopically controlled Ge single-crystal layer grown on a relaxed Si0.2Ge0.8 virtual substrate. The self-diffusivity is enhanced by the compressive strain and its behavior is fully consistent with a theoretical prediction of a generalized activation volume model of a simple vacancy mediated diffusion, reported by Aziz et al.[Phys. Rev. B 73, 054101 (2006)]. The activation volume of (-0.65±0.21) times the Ge atomic volume quantitatively describes the observed enhancement due to the compressive biaxial strain very well.

  10. Strain gage balances and buffet gages

    Ferris, A. T.

    1983-01-01

    One-piece strain gage force balances were developed for use in the National Transonic Facility (NTF). This was accomplished by studying the effects of the cryogenic environment on materials, strain gages, cements, solders, and moisture proofing agents, and selecting those that minimized strain gage output changes due to temperature. In addition, because of the higher loads that may be imposed by the NTF, these balances are designed to carry a larger load for a given diameter than conventional balances. Full cryogenic calibrations were accomplished, and wind tunnel results that were obtained from the Langley 0-3-Meter Transonic Cryogenic Tunnel were used to verify laboratory test results.

  11. Strains in pyrolytic graphite under irradiation

    The studies of strains in pyrolytic graphite caused by development of amorphization in the irradiation zone showed that the local strains attain tens of percent; their distribution is inhomogeneous both in magnitude and in sign. The tendency toward formation of a biaxial field of compressive strains becomes marked with an increase in the fluence, although the formation of small regions in the form of narrow sectors within whose boundaries compression is observed in the radial direction and extension is observed in the tangential direction is also possible. 14 refs., 6 figs

  12. Stability of germanene under tensile strain

    Kaloni, Thaneshwor P.

    2013-09-01

    The stability of germanene under biaxial tensile strain and the accompanying modifications of the electronic properties are studied by density functional theory. The phonon spectrum shows that up to 16% strain the germanene lattice is stable, where the Dirac cone shifts towards higher energy and hole-doped Dirac states are achieved. The latter is due to weakening of the Ge-Ge bonds and reduction of the s-p hybridization. Our calculated Grüneisen parameter shows a similar dependence on the strain as reported for silicene (which is different from that of graphene). © 2013 Elsevier B.V. All rights reserved.

  13. Unit cell of strained GeSi

    The local structure within the unit cell of strained-GeSi layers grown on Si(001) has been examined by polarization-dependent extended x-ray-absorption fine structure. First-neighbor bond lengths are found to deviate only slightly from their unstrained values; however, the distortion of the cubic-unit cell by strain leads to measurable polarization-dependent changes in first-shell coordination and second-shell distances. A unifying picture of bond lengths and elasticity in strained-layer semiconductors is presented. copyright 1997 The American Physical Society

  14. Construction of Killer Wine Yeast Strain

    Seki, Tetsuji; Choi, Eon-Ho; Ryu, Dewey

    1985-01-01

    A double-stranded RNA plasmid which confers the superkiller phenotype was transferred into a wine yeast (Montrachet strain 522) and its leucine-requiring derivative (strain 694) by cytoduction, using the protoplast fusion technique. The killer wine yeast constructed completely suppressed the growth of killer-sensitive strains of Saccharomyces cerevisiae in yeast extract-peptone-glucose medium at pH 4.5, whereas the killer effect was somewhat decreased at pH 3.5. The wine yeast harboring the k...

  15. A new radial strain and strain rate estimation method using autocorrelation for carotid artery

    Ye, Jihui; Kim, Hoonmin; Park, Jongho; Yeo, Sunmi; Shim, Hwan; Lim, Hyungjoon; Yoo, Yangmo

    2014-03-01

    Atherosclerosis is a leading cause of cardiovascular disease. The early diagnosis of atherosclerosis is of clinical interest since it can prevent any adverse effects of atherosclerotic vascular diseases. In this paper, a new carotid artery radial strain estimation method based on autocorrelation is presented. In the proposed method, the strain is first estimated by the autocorrelation of two complex signals from the consecutive frames. Then, the angular phase from autocorrelation is converted to strain and strain rate and they are analyzed over time. In addition, a 2D strain image over region of interest in a carotid artery can be displayed. To evaluate the feasibility of the proposed radial strain estimation method, radiofrequency (RF) data of 408 frames in the carotid artery of a volunteer were acquired by a commercial ultrasound system equipped with a research package (V10, Samsung Medison, Korea) by using a L5-13IS linear array transducer. From in vivo carotid artery data, the mean strain estimate was -0.1372 while its minimum and maximum values were -2.961 and 0.909, respectively. Moreover, the overall strain estimates are highly correlated with the reconstructed M-mode trace. Similar results were obtained from the estimation of the strain rate change over time. These results indicate that the proposed carotid artery radial strain estimation method is useful for assessing the arterial wall's stiffness noninvasively without increasing the computational complexity.

  16. Information about the Current Strain of Clostridium difficile

    ... treatment of this epidemic strain different? How does fluoroquinolone resistance affect management of this strain? What should ... guidelines on internet) Top of page How does fluoroquinolone resistance affect management of this strain? Increased fluoroquinolone ...

  17. Screening of Trichoderma strains tolerant to benzimidazole

    LIU Kai-qi; XIANG Mei-mei; LIU Ren; ZENG Yong-san; ZHOU Hong-zi; YU Jin-feng; JIANG Xin-yin; ZHANG Yue-li

    2004-01-01

    @@ The screening of isolates and the assay of biocontrol mechanisms of Trichoderma were studied systematically in laboratory and greenhouse in vivo. The proteins tolerant to benzimidazole in Trichoderma strains were purified, and their physical and chemical properties were detected. Compared their biological activities in vitro and vivo in greenhouse, nine biocontrol strains (including Ty- 10-2, LTR-2, Tj-5-1, Tj-5-4, Ty- 11-1, Tj-11-3, Ty- 11-3, Tj-3-3-2, Tj-3-3-4) were screened. These biocontrol strains had faster rates of growth and higher inhibition to gray mould (Bortrytis cinerea),and the inhibition was stable. The effects of controlling gray mould in greenhouse with the screened Trichoderma strains were 70 % and 50 % in vivo.

  18. Axillary vein thrombosis mimicking muscular strain.

    Louis, J.

    1999-01-01

    Axillary vein thrombosis may occur on strenuous activity with a clinical picture similar to a simple strain. It carries significant morbidity but a good outcome is possible with early treatment. The aetiology, investigation, and treatment are discussed.

  19. Energy Harvesting Wireless Strain Networks Project

    National Aeronautics and Space Administration — Prime Research LC (PPLC) and Virginia Tech (VT) propose to develop an energy harvesting wireless strain node technology that utilizes single-crystal piezoelectric...

  20. Five challenges in modelling interacting strain dynamics

    Paul S. Wikramaratna

    2015-03-01

    Full Text Available Population epidemiological models where hosts can be infected sequentially by different strains have the potential to help us understand many important diseases. Researchers have in recent years started to develop and use such models, but the extra layer of complexity from multiple strains brings with it many technical challenges. It is therefore hard to build models which have realistic assumptions yet are tractable. Here we outline some of the main challenges in this area. First we begin with the fundamental question of how to translate from complex small-scale dynamics within a host to useful population models. Next we consider the nature of so-called “strain space”. We describe two key types of host heterogeneities, and explain how models could help generate a better understanding of their effects. Finally, for diseases with many strains, we consider the challenge of modelling how immunity accumulates over multiple exposures.

  1. [Improvement of Trichoderma strains for biocontrol].

    Benítez, T; Rey, M; Delgado-Jarana, J; Rincón, A M; Limón, M C

    2000-03-01

    The use of the fungal genus Trichoderma to control fungal plant diseases is a promising alternative to the use of chemical compounds. The aim of this work has been to obtain Trichoderma strains with improved capacity as biological control agents. To do so, the hydrolytic capacity on fungal cell walls of strains of the fungus Trichoderma harzianum has been increased. On one hand, transformation experiments with genes which coded for chitinases and glucanases have been carried out in T. harzianumstra ins. On the other hand, the medium composition has also been modified in order to eliminate proteolytic degradation of some of the overproduced enzymes. Finally, hybrid chitinolytic enzymes with substrate-binding domains have been produced as an alternative to obtain improved biocontrol strains. The transformant strains, when compared with the wild type, showed improved antifungal capacity against the phytopathogenic fungus Rhizoctonia solani, in in vitro experiments. PMID:15762779

  2. Dynamic Force Measurement with Strain Gauges

    Lee, Bruce E.

    1974-01-01

    Discusses the use of four strain gauges, a Wheatstone bridge, and an oscilloscope to measure forces dynamically. Included is an example of determining the centripetal force of a pendulum in a general physics laboratory. (CC)

  3. Design parameters for borehole strain instrumentation

    Gladwin, Michael T.; Hart, Rhodes

    1985-01-01

    The response of a borehole strain meter to hydrostatic and shear deformations in an isotropic medium is calculated to facilitate optimum instrument design and produce instrument response factors for parameters typically encountered in installed instruments. Results for an empty borehole are first compared with results for an instrument in intimate contact with the surrounding rock. The effects of the grout used to install the instrument are then examined. Where possible, analytic forms for the response factors are given. Results for typical installations are then presented in graphical form for optimizing instrument design in an environment of known elastic parameters. Alternatively, the results may be applied in the measurement of unknown strain signals, to correct for instrument response or to provide in-situ estimates of the elastic properties of the environment by examination of observed strain response to known strain signals.

  4. Strain Rate Induced Amorphization in Metallic Nanowires

    Qi, Y.; Cagin, T.; Goddard, W.A. III [Materials and Process Simulation Center, California Institute of Technology, Pasadena, California 91125 (United States); Ikeda, H.; Samwer, K.; Johnson, W.L. [Keck Laboratory of Engineering Materials, California Institute of Technology, Pasadena, California 91125 (United States)

    1999-04-01

    Using molecular dynamics simulations with a many-body force field, we studied the deformation of single crystal Ni and NiCu random alloy nanowires subjected to uniform strain rates but kept at 300thinspthinspK. For all strain rates, the Ni nanowire is elastic up to 7.5{percent} strain with a yield stress of 5.5thinspthinspGPa, far above that of bulk Ni. At high strain rates, we find that for both systems the crystalline phase transforms continuously to an amorphous phase, exhibiting a dramatic change in atomic short-range order and a near vanishing of the tetragonal shear elastic constant perpendicular to the tensile direction. This amorphization which occurs directly from the homogeneous, elastically deformed system with no chemical or structural inhomogeneities exhibits a new mode of amorphization. {copyright} {ital 1999} {ital The American Physical Society}

  5. 3D Morphing Using Strain Field Interpolation

    Han-Bing Yan; Shi-Min Hu; Ralph R Martin

    2007-01-01

    In this paper, we present a new technique based on strain fields to carry out 3D shape morphing for applicationsin computer graphics and related areas.Strain is an important geometric quantity used in mechanics to describe the deformation of objects.We apply it in a novel way to analyze and control deformation in morphing.Using position vector fields, the strain field relating source and target shapes can be obtained.By interpolating this strain field between zero and a final desired value we can obtain the position field for intermediate shapes.This method ensures that the 3D morphing process is smooth.Locally, volumes suffer minimal distortion, and no shape jittering or wobbling happens: other methods do not necessarily have these desirable properties.We also show how to control the method so that changes of shape (in particular, size changes) vary linearly with time.

  6. Five challenges in modelling interacting strain dynamics

    Wikramaratna, Paul S; Kurcharski, Adam; Gupta, Sunetra;

    2015-01-01

    Population epidemiological models where hosts can be infected sequentially by different strains have the potential to help us understand many important diseases. Researchers have in recent years started to develop and use such models, but the extra layer of complexity from multiple strains brings...... with it many technical challenges. It is therefore hard to build models which have realistic assumptions yet are tractable. Here we outline some of the main challenges in this area. First we begin with the fundamental question of how to translate from complex small-scale dynamics within a host to...... useful population models. Next we consider the nature of so-called “strain space”. We describe two key types of host heterogeneities, and explain how models could help generate a better understanding of their effects. Finally, for diseases with many strains, we consider the challenge of modelling how...

  7. Strain Gauges Mounted To Retain Calibration

    Butler, Barry L.

    1993-01-01

    Silicon-based semiconductor strain gauges mounted in such way they retain original calibration for several years instead of few months. Improvement effected by bonding gauges to ceramic substrates with glasses instead of epoxies as adhesives.

  8. Broken Bones, Sprains, and Strains (For Parents)

    ... 5 Things to Know About Zika & Pregnancy Broken Bones, Sprains, and Strains KidsHealth > For Parents > Broken Bones, ... home. What to Do: For a Suspected Broken Bone: Do not move a child whose injury involves ...

  9. Strain field of a buried oxide aperture

    Kießling, F.; Niermann, T.; Lehmann, M.; Schulze, J.-H.; Strittmatter, A.; Schliwa, A.; Pohl, U. W.

    2015-02-01

    The strain field of an AlOx current aperture, fabricated by selective oxidation of an AlAs/GaAs layer buried in a circular GaAs mesa, is studied. Components of the strain tensor for a thin cross-section lamella cut out of such a structure are evaluated from dark-field electron holography, proving the validity of simulations based on linear elasticity. Simulation of the entire structure is utilized to prepare mesa surfaces with tailored strain fields for controlling the nucleation site of InGaAs quantum dots. The experimental proof of strain simulations allows estimating the magnitude of piezoelectricity, yielding for the studied mesa structures a piezoelectric potential up to 50 mV.

  10. Microalgal Strains Sent to External Users

    National Oceanic and Atmospheric Administration, Department of Commerce — Over 200 microalgal strains maintained in the Milford Microalgal Culture Collection are available to aquaculture facilities and researchers. Approximately 100...

  11. Review of strain buckling: analysis methods

    This report represents an attempt to review the mechanical analysis methods reported in the literature to account for the specific behaviour that we call buckling under strain. In this report, this expression covers all buckling mechanisms in which the strains imposed play a role, whether they act alone (as in simple buckling under controlled strain), or whether they act with other loadings (primary loading, such as pressure, for example). Attention is focused on the practical problems relevant to LMFBR reactors. The components concerned are distinguished by their high slenderness ratios and by rather high thermal levels, both constant and variable with time. Conventional static buckling analysis methods are not always appropriate for the consideration of buckling under strain. New methods must therefore be developed in certain cases. It is also hoped that this review will facilitate the coding of these analytical methods to aid the constructor in his design task and to identify the areas which merit further investigation

  12. Tuning strain in flexible graphene nanoelectromechanical resonators

    Guan, Fen; Kumaravadivel, Piranavan; Averin, Dmitri V.; Du, Xu

    2015-11-01

    The structural flexibility of low dimensional nanomaterials offers unique opportunities for studying the impact of strain on their physical properties and for developing innovative devices utilizing strain engineering. A key towards such goals is a device platform which allows the independent tuning and reliable calibration of the strain. Here, we report the fabrication and characterization of graphene nanoelectromechanical resonators (GNEMRs) on flexible substrates. Combining substrate bending and electrostatic gating, we achieve the independent tuning of the strain and sagging in graphene and explore the nonlinear dynamics over a wide parameter space. Analytical and numerical studies of a continuum mechanics model, including the competing higher order nonlinear terms, reveal a comprehensive nonlinear dynamics phase diagram, which quantitatively explains the complex behaviors of GNEMRs.

  13. Survival and activity of individual bioaugmentation strains

    Dueholm, Morten Simonsen; G. Marquesa, Irina; Karst, Søren Michael;

    2015-01-01

    Successful application of bioaugmentation for enhanced degradation of environmental pollutants is often limited by the lack of methods to monitor the survival and activity of individual bioaugmentation strains. However, recent advancements in sequencing technologies and molecular techniques now a...

  14. Strain imaging by Bragg edge neutron transmission

    Santisteban, J R; Fitzpatrick, M E; Steuwer, A; Withers, P J; Daymond, M R; Johnson, M W; Rhodes, N; Schooneveld, E M

    2002-01-01

    The Bragg edges appearing in the transmitted time-of-flight spectra of polycrystalline materials have been recorded using a two-dimensional array of detectors. Subsequent analysis has enabled maps of the elastic strain to be produced.

  15. Some remarks on the strain decomposition

    F. Nicot; Darve, F.

    2006-01-01

    An impressive amount of constitutive relations have been developed in the past few decades. With respect to the class of elasto-plastic phenomenological models, elastic and plastic strain decomposition is generally stated as a basic assumption, so as to treat the elastic (i.e., recoverable) and plastic (i.e., unrecoverable) parts of the strains separately. For incrementally nonlinear relations this decomposition is not possible. In a first part of this paper a detailed discussion of elastic a...

  16. Framework for Concentrated Strain Deployable Trusses

    Mejia-Ariza, Juan Manuel

    2008-01-01

    This research presents a simplified framework for the analysis of deployable trusses using the concentrated strain approach and uses it to provide key insights into the many design decisions to be made in the development of concentrated strain architectures. The framework uses Euler Column Theory to derive closed form solutions to estimate truss performance. The results are compared to a classical solution and shown to give similar results. A range of strut and hinge hierarchy choices are con...

  17. High-Temperature Adhesive Strain Gage Developed

    Pereira, J. Michael; Roberts, Gary D.

    1997-01-01

    Researchers at the NASA Lewis Research Center have developed a unique strain gage and adhesive system for measuring the mechanical properties of polymers and polymer composites at elevated temperatures. This system overcomes some of the problems encountered in using commercial strain gages and adhesives. For example, typical commercial strain gage adhesives require a postcure at temperatures substantially higher than the maximum test temperature. The exposure of the specimen to this temperature may affect subsequent results, and in some cases may be higher than the glass-transition temperature of the polymer. In addition, although typical commercial strain gages can be used for short times at temperatures up to 370 C, their long-term use is limited to 230 C. This precludes their use for testing some high-temperature polyimides near their maximum temperature capability. Lewis' strain gage and adhesive system consists of a nonencapsulated, unbacked gage grid that is bonded directly to the polymer after the specimen has been cured but prior to the normal postcure cycle. The gage is applied with an adhesive specially formulated to cure under the specimen postcure conditions. Special handling, mounting, and electrical connection procedures were developed, and a fixture was designed to calibrate each strain gage after it was applied to a specimen. A variety of tests was conducted to determine the performance characteristics of the gages at elevated temperatures on PMR-15 neat resin and titanium specimens. For these tests, which included static tension, thermal exposure, and creep tests, the gage and adhesive system performed within normal strain gage specifications at 315 C. An example of the performance characteristics of the gage can be seen in the figure, which compares the strain gage measurement on a polyimide specimen at 315 C with an extensometer measurement.

  18. Relations between microbarograph and strain data

    Mentes, G.; Eper-Pápai, I.

    2009-01-01

    Abstract The relationship between barometric and strain data related to seasonal characteristics within a year was studied on the basis of parallel records from a quartz tube extensometer and a microbarograph at the Geodynamical Observatory in Sopronbanfalva, Hungary. Both strain and barometric data series were combined into groups according to the three `Lloyd? seasons and they were subjected to spectrum, tidal, regression and coherence analysis. All of the analysis methods establ...

  19. FRP rupture strains in FRP wrapped columns

    Li, Shiqing

    2012-01-01

    Applying lateral confinement to concrete columns using fibre-reinforced polymer (FRP) composites is a very promising technique. FRP rupture is the typical failure mode of FRP wrapped columns under axial compression. numerous experiments have shown that the FRP rupture strain in an FRP wrapped circular column is significantly lower than the FRP ultimate rupture strain determined from flat coupon test of FRP. Despite a large number of studies on the application of FRP confined columns, the mech...

  20. Conductive lithographic film fabricated resistive strain gauges

    Hay, GI; Evans, PSA; Harrison, DJ; Southee, DJ; Simpson, G; Harrey, PM

    2003-01-01

    This paper reports progress in sensor fabrication by the conductive lithographic film (CLF) printing process. Work describing strain sensitive structures manufactured using a modified printing process and conductive inks are addressed. The performance of a 'single ink' strain sensitive structure when printed on six alternative polymer substrates (GlossArt, PolyArt, Teslin, Mylar C, Mylar and Kapton) is analysed. Though not intending to compete with conventional gauges in high tolerance measur...

  1. Characterization of lithographically printed resistive strain gauges

    Hay, G.I.; Evans, P.S.A.; Harrison, D J; Southee, D; Simpson, G; Harrey, P.M.

    2005-01-01

    This paper reports progress in sensor fabrication by the conductive lithographic film (CLF) printing process. Work describing strain-sensitive structures manufactured using a modified printing process and conductive inks is addressed. The performance of a "single-ink" strain-sensitive structure when printed on six alternative substrates (GlossArt, PolyArt, Teslin, Mylar C, Melinex, and Kapton) is analyzed. Though not intending to compete with conventional gauges in high-tolerance measurement,...

  2. Hydraulic Calibrator for Strain-Gauge Balances

    Skelly, Kenneth; Ballard, John

    1987-01-01

    Instrument for calibrating strain-gauge balances uses hydraulic actuators and load cells. Eliminates effects of nonparallelism, nonperpendicularity, and changes of cable directions upon vector sums of applied forces. Errors due to cable stretching, pulley friction, and weight inaccuracy also eliminated. New instrument rugged and transportable. Set up quickly. Developed to apply known loads to wind-tunnel models with encapsulated strain-gauge balances, also adapted for use in calibrating dynamometers, load sensors on machinery and laboratory instruments.

  3. Strain gauge for high temperature tests

    A strain gauge is described that is intended to measure longitudinal and lateral strains during tubular specimen loading by an axial force and internal pressure at test temperatures up to 1000 K. The use of the gauge for creep study of steel type Kh18N10T at 870 K under complex stress state is given as an example. Experimental data confirm the suitability of the gauge for the purpose mentioned and sufficient accuracy of parameters determined. 3 refs., 3 figs

  4. Laboratory evolution of copper tolerant yeast strains

    Adamo Giusy; Brocca Stefania; Passolunghi Simone; Salvato Benedetto; Lotti Marina

    2012-01-01

    Abstract Background Yeast strains endowed with robustness towards copper and/or enriched in intracellular Cu might find application in biotechnology processes, among others in the production of functional foods. Moreover, they can contribute to the study of human diseases related to impairments of copper metabolism. In this study, we investigated the molecular and physiological factors that confer copper tolerance to strains of baker's yeasts. Results We characterized the effects elicited in ...

  5. Deformation strain inhomogeneity in columnar grain nickel

    Wu, G.L.; Godfrey, A.; Juul Jensen, D.;

    2005-01-01

    A method is presented for determination of the local deformation strain of individual grains in the bulk of a columnar grain sample. The method, based on measurement of the change in grain area of each grain, is applied to 12% cold rolled nickel. Large variations are observed in the local strain...... associated with each grain. (c) 2005 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved....

  6. Cranial bone morphometric study among mouse strains

    Yamamura Ken-ichi; Kawakami Minoru

    2008-01-01

    Abstract Background Little is known about the molecular mechanism which regulates how the whole cranium is shaped. Mouse models currently available for genetic research include several hundreds of unique inbred strains and genetically engineered mutants. By cross comparing their genomic structures, we can elucidate the cause of any differences in the phenotype between two strains. The craniometry of subspecies, or closely related species, of mice provide a good systemic model to study the rel...

  7. A tunable strain sensor using nanogranular metals

    Friedemann Völklein; Alexander Kaya; Jens Müller; Pintu Das; Heiko Reith; Fabrizio Porrati; Roland Sachser; Markus Baranowski; Christina Grimm; Schwalb, Christian H.; Michael Huth

    2010-01-01

    This paper introduces a new methodology for the fabrication of strain-sensor elements for MEMS and NEMS applications based on the tunneling effect in nano-granular metals. The strain-sensor elements are prepared by the maskless lithography technique of focused electron-beam-induced deposition (FEBID) employing the precursor trimethylmethylcyclopentadienyl platinum [MeCpPt(Me)3]. We use a cantilever-based deflection technique to determine the sensitivity (gauge factor) of the sensor element. W...

  8. Elastic constants from microscopic strain fluctuations

    Sengupta, Surajit; Nielaba, Peter; Rao, Madan; Binder, K.

    1999-01-01

    Fluctuations of the instantaneous local Lagrangian strain $\\epsilon_{ij}(\\bf{r},t)$, measured with respect to a static ``reference'' lattice, are used to obtain accurate estimates of the elastic constants of model solids from atomistic computer simulations. The measured strains are systematically coarse- grained by averaging them within subsystems (of size $L_b$) of a system (of total size $L$) in the canonical ensemble. Using a simple finite size scaling theory we predict the behaviour of th...

  9. Elastically Relaxed Free-standing Strained-Si Nanomembranes

    Roberts, Michelle M.; Klein, Levente J.; Savage, Don E.; Slinker, Keith A.; Friesen, Mark; Celler, George; Eriksson, Mark A.; Lagally, Max G.

    2006-01-01

    Strain plays a critical role in the properties of materials. In silicon and silicon-germanium, strain provides a mechanism for control of both carrier mobility and band offsets. In materials integra-tion, strain is typically tuned through the use of dislocations and elemental composition. We demonstrate a versatile method to control strain, by fabricating membranes in which the final strain state is controlled by elastic strain sharing, i.e., without the formation of defects. We grow Si/SiGe ...

  10. Strain-tunable Josephson current in graphene-superconductor junction

    Wang, Y.; Liu, Y.; Wang, B.

    2013-10-01

    Strain effects on Josephson current in a graphene-superconductor junction are explored theoretically. It is demonstrated that the supercurrent is an oscillatory function of zigzag direction strain with a strain-dependent oscillating frequency. Interestingly, it is found that the Josephson current under armchair direction strain can be turned on/off with a cutoff strain. In view of the on/off properties of the Josephson current, we propose the strained graphene Josephson junction to be utilized as a supercurrent switch.

  11. Whole Genome Analysis of a Wine Yeast Strain

    Hauser, Nicole C.; Kurt Fellenberg; Rosario Gil; Sonja Bastuck; Hoheisel, Jörg D; Pérez-Ortín, José E.

    2001-01-01

    Saccharomyces cerevisiae strains frequently exhibit rather specific phenotypic features needed for adaptation to a special environment. Wine yeast strains are able to ferment musts, for example, while other industrial or laboratory strains fail to do so. The genetic differences that characterize wine yeast strains are poorly understood, however. As a first search of genetic differences between wine and laboratory strains, we performed DNA-array analyses on the typical wine yeast strain T73 an...

  12. The mechanical consequences of load bearing in the equine third metacarpal across speed and gait: the nonuniform distributions of normal strain, shear strain, and strain energy density

    Rubin, Clinton T.; Seeherman, Howard; Qin, Yi-Xian; Gross, Ted S.

    2013-01-01

    Distributions of normal strain, shear strain, and strain energy density (SED) were determined across the midshaft of the third metacarpal (MCIII, or cannon bone) of 3 adult thoroughbred horses as a function of speed and gait. A complete characterization of the mechanical demands of the bone made through the stride and from mild through the extremes of locomotion was possible by using three 3-element rosette strain gauges bonded at the diaphyseal midshaft of the MCIII and evaluating the strain...

  13. Commonly administered BCG strains including an evolutionarily early strain and evolutionarily late strains of disparate genealogy induce comparable protective immunity against tuberculosis

    Horwitz, Marcus A.; Harth, Günter; Dillon, Barbara Jane; Masleša-Gali, Saša

    2008-01-01

    BCG has been administered to over 4 billion persons worldwide, but its efficacy in preventing tuberculosis in adults has been highly variable. One hypothesis for its variability is that different strains of BCG vary in protective efficacy, and moreover, that evolutionarily early strains are more efficacious than the more attenuated evolutionarily late strains, which lack region of deletion 2. To examine this hypothesis, we tested six widely used BCG strains – the evolutionarily early strain B...

  14. Differentiation of Mycoplasma gallisepticum Strains through RFLP

    Luis José Carrión

    2012-12-01

    Full Text Available Avian mycoplasmosis is a disease that considerably affects the poultry sector, which is reflected in the decrease of the production parameters in fertile and commercial egg laying broilers. Presentation costs are so high that it is impossible for the poultry industry to survive without thinking of its effective control or eradication. There is great interest in the type of M. gallisepticum (Mg strains, both vaccine and field, which are key aspects to handle the disease, but there is still no definitive method for Mg strain characterization. Genes related to surface proteins —gapA and mgc2,lipoprotein (lp— that make it possible to identify and characterize the Mg genomically are currently being studied. In this study, regions of the lp gene were amplified from strains F and Ts-11 of Mg through the polymerase chain reaction (PCR technique, which gave an amplicon of 455 bp for each of the strains; each of the amplicons was applied the restriction fragment length polymorphism (RFLP test with the Taq I enzyme, which made it possible to differentiate vaccine strains from field strains obtained from tracheal swab samples taken at commercial farms. It was demonstrated that PCRRFLP is an appropriate method of diagnosis of mycoplasmosis in our environment.

  15. Instrument for measuring fuel cladding strain

    Development work to provide instrumentation for the continuous measurement of strain of material specimens such as nuclear fuel cladding has shown that a microwave sensor and associated instrumentation hold promise. The cylindrical sensor body enclosing the specimen results in a coaxial resonator absorbing microwave energy at frequencies dependent upon the diameter of the specimen. Diametral changes of a microinch can be resolved with use of the instrumentation. Very reasonable values of elastic strain were measured at 750F and 10000F for an internally pressurized 20 percent C.W. 316 stainless steel specimen simulating nuclear fuel cladding. The instrument also indicated the creep strain of the same specimen pressurized at 6500 psi and at a temperature of 10000F for a period of 700 hours. Although the indicated strain appears greater than actual, the sensor/specimen unit experienced considerable oxidation even though an inert gas purge persisted throughout the test duration. By monitoring at least two modes of resonance, the measured strain was shown to be nearly independent of sensor temperature. To prevent oxidation, a second test was performed in which the specimen/sensor units were contained in an evacuated enclosure. The strain of the two prepressurized specimens as indicated by the microwave instrumentation agreed very closely with pre- and post-test measurements obtained with use of a laser interferometer

  16. Strain effect in REBCO coated conductors

    The strain effect on critical current (Ic) in REBCO coated conductors has been intensively investigated owing to its importance for practical applications. The change in Ic with applied strain can be divided into two phenomena; namely reversible variation within elastic deformation for superconducting film, and irreversible degradation related to brittle fracture. REBCO coated conductor is the first material among various high temperature superconductors in which the non-linear reversible change in Ic with uniaxial strain is markedly observed. High stress (strain) tolerance in coated conductors is one of the advantages compared with other superconducting composites, and there are high expectations for application to high-field magnets based on such superior mechanical properties. In this review article, recent research results on the mechanical properties of REBCO coated conductors are summarized, including the stress-strain characteristic for substrate materials, the strain effect on Ic and the experimental techniques for evaluating these properties. Delamination has been recognized as one of the most critical issues for coil applications. Several evaluation methods for delamination strength and interlaminar fracture toughness were introduced. (author)

  17. Strain-displacement relations for strain engineering in single-layer 2d materials

    Midtvedt, Daniel; Lewenkopf, Caio H.; Croy, Alexander

    2016-03-01

    We investigate the electromechanical coupling in single-layer 2d materials. For non-Bravais lattices, we find important corrections to the standard macroscopic strain-microscopic atomic-displacement theory. We put forward a general and systematic approach to calculate strain-displacement relations for several classes of 2d materials. We apply our findings to graphene as a study case, by combining a tight binding and a valence force-field model to calculate electronic and mechanical properties of graphene nanoribbons under strain. The results show good agreement with the predictions of the Dirac equation coupled to continuum mechanics. For this long wave-limit effective theory, we find that the strain-displacement relations lead to a renormalization correction to the strain-induced pseudo-magnetic fields. A similar renormalization is found for the strain-induced band-gap of black phosphorous. Implications for nanomechanical properties and electromechanical coupling in 2d materials are discussed.

  18. Strain fields adjacent to bone-implant interfaces: strain field analysis using digital image correlation techniques

    Ribeiro, J. E.; Monteiro, J.; Lopes, H.; Vaz, M.A.P.; Guedes, R.M.

    2008-01-01

    When using conventional surface strain measurement techniques (e.g. strain gauges, dial gauges), the measurement of deformations within cancellous bone is frequently hampered by the material’s highly porous structure and poor mechanical properties. Although detailed strain maps derived from actual experimental data have the potential to resolve many questions concerning the mechanics of cancellous bone, the traditional method of producing maps through measurements with optical techniques has ...

  19. Gendered Responses to Serious Strain: The Argument for a General Strain Theory of Deviance

    Kaufman, Joanne M.

    2009-01-01

    This paper expands and builds on newer avenues in research on gender and general strain theory (GST). I accomplish this by focusing on serious strains that are relevant for males and females, including externalizing and internalizing forms of negative emotions, and including multiple gendered deviant outcomes. Using the Add Health dataset, I find strong support for the impact of serious strains on both types of negative emotions and different forms of deviance for males and females. However, ...

  20. The influence of strain rate and hydrogen on the plane-strain ductility of Zircaloy cladding

    Link, T.M.; Motta, A.T.; Koss, D.A. [Pennsylvania State Univ., University Park, PA (United States)

    1998-03-01

    The authors studied the ductility of unirradiated Zircaloy-4 cladding under loading conditions prototypical of those found in reactivity-initiated accidents (RIA), i.e.: near plane-strain deformation in the hoop direction (transverse to the cladding axis) at room temperature and 300 C and high strain rates. To conduct these studies, they developed a specimen configuration in which near plane-strain deformation is achieved in the gage section, and a testing methodology that allows one to determine both the limit strain at the onset of localized necking and the fracture strain. The experiments indicate that there is little effect of strain rate (10{sup {minus}3} to 10{sup 2} s{sup {minus}1}) on the ductility of unhydrided Zircaloy tubing deformed under near plane-strain conditions at either room temperature or 300 C. Preliminary experiments on cladding containing 190 ppm hydrogen show only a small loss of fracture strain but no clear effect on limit strain. The experiments also indicate that there is a significant loss of Zircaloy ductility when surface flaws are present in the form of thickness imperfections.

  1. True stress-strain curve acquisition for irradiated stainless steel including the range exceeding necking strain

    Kamaya, Masayuki; Kitsunai, Yuji; Koshiishi, Masato

    2015-10-01

    True stress-strain curves were obtained for irradiated 316L stainless steel by a tensile test and by a curve estimation procedure. In the tensile test, the digital image correlation technique together with iterative finite element analysis was applied in order to identify curves for strain larger than the necking strain. The true stress-strain curves were successfully obtained for the strain of more than 0.4 whereas the necking strain was about 0.2 in the minimum case. The obtained true stress-strain curves were approximated well with the Swift-type equation including the post-necking strain even if the exponential constant n was fixed to 0.5. Then, the true stress-strain curves were estimated by a curve estimation procedure, which was referred to as the K-fit method. Material properties required for the K-fit method were the yield and ultimate strengths or only the yield strength. Some modifications were made for the K-fit method in order to improve estimation accuracy for irradiated stainless steels.

  2. Variation in the strain anisotropy of Zircaloy with temperature and strain

    Strain anisotropy was investigated at temperatures in the range 293 to 1117K in circular tensile specimens prepared from rolled Zircaloy-2 plate so that their tensile axes were parallel to and transverse to the rolling direction. The strain anisotropy factor for both types of specimen increased markedly in the high alpha phase region above 923K reaching a maximum at circa 1070K. Above this temperature in the alpha-plus-beta phase region the strain anisotropy decreased rapidly as the proportion of beta phase increased and was almost non-existent at 1173K. The strain anisotropy was markedly strain dependent, particularly in the high alpha phase region. The study was extended to Zircaloy-4 pressurized water reactor (PWR) 17 x 17 type fuel rod tubing specimens which were strained under biaxial conditions using cooling conditions which promoted uniform diametral strain over most of their lengths (circa 250 mm). In these circumstances the strain anisotropy is manifest by a reduction in length. Measurement of this change along with that in diameter and wall thickness produced data from which the strain anisotropy factor was calculated. The results, although influenced by additional factors discussed in the paper, were similar to those observed in the uniaxial Zircaloy-2 tensile tests. (author)

  3. Elastocaloric cooling processes: The influence of material strain and strain rate on efficiency and temperature span

    Schmidt, Marvin; Schütze, Andreas; Seelecke, Stefan

    2016-06-01

    This paper discusses the influence of material strain and strain rate on efficiency and temperature span of elastocaloric cooling processes. The elastocaloric material, a newly developed quaternary Ni-Ti-Cu-V alloy, is characterized at different maximum strains and strain rates. The experiments are performed with a specially designed test setup, which enables the measurement of mechanical and thermal process parameters. The material efficiency is compared to the efficiency of the Carnot process at equivalent thermal operation conditions. This method allows for a direct comparison of the investigated material with other caloric materials.

  4. Strain distribution analysis of sputter-formed strained Si by tip-enhanced Raman spectroscopy

    Hanafusa, H; Hirose, N.; Kasamatsu, A; Mimura, T; Matsui, T; Chong, H.M.H.; Mizuta, H.; Suda, Y.

    2011-01-01

    Simultaneous nanometer-scale measurements of the strain and surface undulation distributions of strained Si (s-Si) layers on strain-relief quadruple-Si1-xGex-layer buffers, using a combined atomic force microscopy (AFM) and tip-enhanced Raman spectroscopy (TERS) system, clarify that an s-Si sample formed by our previously proposed sputter epitaxy method has a smoother and more uniformly strained surface than an s-Si sample formed by gas-source molecular beam epitaxy. The TERS analyses suggest...

  5. Inexpensive Implementation of Many Strain Gauges

    Berkun, Andrew C.

    2010-01-01

    It has been proposed to develop arrays of strain gauges as arrays of ordinary metal film resistors and associated electronic readout circuitry on printed circuit boards or other suitable substrates. This proposal is a by-product of a development of instrumentation utilizing metal film resistors on printed-circuit boards to measure temperatures at multiple locations. In the course of that development, it was observed that in addition to being sensitive to temperature, the metal film resistors were also sensitive to strains in the printed-circuit boards to which they were attached. Because of the low cost of ordinary metal film resistors (typically strain gauges, possibly concentrated in small areas. For example, such an array could be designed for use as a computer keyboard with no moving parts, as a device for sensing the shape of an object resting on a surface, or as a device for measuring strains at many points on a mirror, a fuel tank, an airplane wing, or other large object. Ordinarily, the effect of strain on resistance would be regarded as a nuisance in a temperature-measuring application, and the effect of temperature on resistance would be regarded as a nuisance in a strain-measuring application. The strain-induced changes in resistance of the metal film resistors in question are less than those of films in traditional strain gauges. The main novel aspect of present proposal lies in the use of circuitry affording sufficient sensitivity to measure strain plus means for compensating for the effect of temperature. For an array of metal film resistors used as proposed, the readout circuits would include a high-accuracy analog-to-digital converter fed by a low noise current source, amplifier chain, and an analog multiplexer chain. Corrections would be provided by use of high-accuracy calibration resistors and a temperature sensor. By use of such readout circuitry, it would be possible to read the resistances of as many as 100 fixed resistors in a time interval

  6. Anisotropic nature of radially strained metal tubes

    Strickland, Julie N.

    Metal pipes are sometimes swaged by a metal cone to enlarge them, which increases the strain in the material. The amount of strain is important because it affects the burst and collapse strength. Burst strength is the amount of internal pressure that a pipe can withstand before failure, while collapse strength is the amount of external pressure that a pipe can withstand before failure. If the burst or collapse strengths are exceeded, the pipe may fracture, causing critical failure. Such an event could cost the owners and their customers millions of dollars in clean up, repair, and lost time, in addition to the potential environmental damage. Therefore, a reliable way of estimating the burst and collapse strength of strained pipe is desired and valuable. The sponsor currently rates strained pipes using the properties of raw steel, because those properties are easily measured (for example, yield strength). In the past, the engineers assumed that the metal would be work-hardened when swaged, so that yield strength would increase. However, swaging introduces anisotropic strain, which may decrease the yield strength. This study measured the yield strength of strained material in the transverse and axial direction and compared them to raw material, to determine the amount of anisotropy. This information will be used to more accurately determine burst and collapse ratings for strained pipes. More accurate ratings mean safer products, which will minimize risk for the sponsor's customers. Since the strained metal has a higher yield strength than the raw material, using the raw yield strength to calculate burst and collapse ratings is a conservative method. The metal has even higher yield strength after strain aging, which indicates that the stresses are relieved. Even with the 12% anisotropy in the strained and 9% anisotropy in the strain aged specimens, the raw yield strengths are lower and therefore more conservative. I recommend that the sponsor continue using the raw

  7. [Acetobutylic fermentation: strains and regional raw materials].

    Benassi, F O; Bloos, R K; de Rambaldo, L A

    1983-01-01

    The purpose of the present work was to show, as a first stage, that it is possible to characterize autochtohnous strains of Clostridium acetobutilicum of a good solvent producing capacity, specially N-butanol, through the utilization of suitable techniques for isolating anaerobic microorganisms. Cassava roots were employed as raw material using suitable culture media and an anaerobic jar of cold catalyst. The fermentative capacity of the strains thus isolated was evaluated against a control strain of Clostridium acetobutilicum. Even though some of the strains showed a greater solvent producing power, most of them showed lower fermentation capacity than the control strain, which could be increased, by applying successive thermic treatments. As a second stage, and due to the low cost production of cassava in the Province of Misiones, we studied its utilization as an acetone-butanol fermentation substrate. Mashes composed of binary mixtures of cassava flour and variable amounts of integral flour maize or soy were treated with selected "starters" of Clostridium acetobutilicum, being further processed according to standardized techniques in order to obtain the already mentioned solvents. Mashes concentration influence was also studied using culture media the composition of which proved to be excellent in all experiments carried out under "static system" conditions. The highest fermentative yields (maximum value recorded: 26,20 g of total solvents, with respect to dry solids), were recorded for mashes obtained from mixtures containing integral maize flour; these showed a higher degree of nutrients utilization than those prepared with integral soy flour. PMID:6400763

  8. Strain Echocardiography in Acute Cardiovascular Diseases.

    Favot, Mark; Courage, Cheryl; Ehrman, Robert; Khait, Lyudmila; Levy, Phillip

    2016-01-01

    Echocardiography has become a critical tool in the evaluation of patients presenting to the emergency department (ED) with acute cardiovascular diseases and undifferentiated cardiopulmonary symptoms. New technological advances allow clinicians to accurately measure left ventricular (LV) strain, a superior marker of LV systolic function compared to traditional measures such as ejection fraction, but most emergency physicians (EPs) are unfamiliar with this method of echocardiographic assessment. This article discusses the application of LV longitudinal strain in the ED and reviews how it has been used in various disease states including acute heart failure, acute coronary syndromes (ACS) and pulmonary embolism. It is important for EPs to understand the utility of technological and software advances in ultrasound and how new methods can build on traditional two-dimensional and Doppler techniques of standard echocardiography. The next step in competency development for EP-performed focused echocardiography is to adopt novel approaches such as strain using speckle-tracking software in the management of patients with acute cardiovascular disease. With the advent of speckle tracking, strain image acquisition and interpretation has become semi-automated making it something that could be routinely added to the sonographic evaluation of patients presenting to the ED with cardiovascular disease. Once strain imaging is adopted by skilled EPs, focused echocardiography can be expanded and more direct, phenotype-driven care may be achievable for ED patients with a variety of conditions including heart failure, ACS and shock. PMID:26823931

  9. Crack initiation under generalized plane strain conditions

    A method for estimating the decrease in crack-initiation toughness, from a reference plane strain value, due to positive straining along the crack front of a circumferential flaw in a reactor pressure vessel is presented in this study. This method relates crack initiation under generalized plane strain conditions with material failure at points within a distance of a few crack-tip-opening displacements ahead of a crack front, and involves the formulation of a micromechanical crack-initiation model. While this study is intended to address concerns regarding the effects of positive out-of- plane straining on ductile crack initiation, the approach adopted in this work can be extended in a straightforward fashion to examine conditions of macroscopic cleavage crack initiation. Provided single- parameter dominance of near-tip fields exists in the flawed structure, results from this study could be used to examine the appropriateness of applying plane strain fracture toughness to the evaluation of circumferential flaws, in particular to those in ring-forged vessels which have no longitudinal welds. In addition, results from this study could also be applied toward the analysis of the effects of thermal streaming on the fracture resistance of circumferentially oriented flaws in a pressure vessel. 37 refs., 8 figs., 1 tab

  10. Multiwalled carbon nanotube film for strain sensing

    We have studied the possibility of using multiwalled carbon nanotube (MWCNT) films as strain sensors. The MWCNT films were prepared by a solution/filtration method and were bonded directly onto specimens by a nonconductive adhesive. For comparison, conventional foil strain gages were also bonded to the structure on the opposite side. The specimens then underwent a uniaxial tensile load-unload cycle to evaluate them as strain sensors. To ensure good electrical contact between carbon nanotube film and the wires, a thin layer of copper was thermally deposited on both ends of the film as electrodes, and the wires were connected to the electrodes by silver ink. Wheatstone bridges were used to convert the resistance changes of the MWCNTs to voltage output. Results indicated that the output voltages were proportional to the strain readings from the stain indicator. The effect of temperature on the resistance was measured and the MWCNT film resistance was found to be independent of temperature over the range 273-363 K. The optimal film dimension for strain sensing was evaluated as well. Dynamic tests suggest that the MWCNTs were able to extract the structural signature. Our results indicate that MWCNT film is potentially useful for structural health monitoring and vibration control applications

  11. Methodology to measure strains at high temperatures using electrical strain gages with free filaments

    An experimental methodology used for strains measuring at high temperatures is show in this work. In order to do the measurements, it was used electric strain gages with loose filaments attached to a stainless steel 304 beam with specific cements. The beam has triangular shape and a constant thickness, so the strain is the same along its length. Unless the beam surface be carefully prepared, the strain gage attachment is not efficient. The showed results are for temperatures ranging from 20 deg C to 300 deg C, but the experimental methodology could be used to measure strains at a temperature up to 900 deg C. Analytical calculations based on solid mechanics were used to verify the strain gage electrical installation and the measured strains. At a first moment, beam deformations as a temperature function were plotted. After that, beam deformations with different weighs were plotted as a temperature function. The results shown allowed concluding that the experimental methodology is trustable to measure strains at temperatures up to 300 deg C. (author)

  12. Development of the invar36 thin film strain gauge sensor for strain measurement

    This paper presents development of invar36 thin film strain gauges of various thicknesses ranging from 100 to 1400 Å for strain measurement. The strain gauges are deposited on microslides using the dc magnetron sputtering technique. Resistivity, temperature coefficient of resistance (TCR) and gauge factors of all gauges are measured and compared with each other. TCR is estimated by systematic annealing of gauges in vacuum and found as low as 190 ppm °C−1. A four-point bending setup is designed and fabricated to measure the gauge factors of all gauges. The gauge factor of relatively thinner strain gauge is found as high as 4.5 and for strain gauges with thickness greater than 500 Å gauge factor is found less than 2.5. The variations of gauge resistance with applied strain are studied in terms of linearity, hysteresis and repeatability. The developed strain gauges are connected in a full-bridge configuration and the output response to the applied strain is studied at different excitation voltages. (paper)

  13. Measurement of high temperature strain by the laser-speckle strain gauge

    Yamaguchi, I.

    1984-01-01

    By using the laser-speckle strain gauge, the strain of metal at the temperature lower than 250 C is measured. The principle of the gauge is to measure the expansion or contraction of the fine structures of surface by detecting the resultant speckle displacement in an optoelectronic way, whereby the effect of rigid-body motion is automatically cancelled out with the aid of a differential detection system. A transportable apparatus was built and a comparison experiment performed with a resistance strain gauge at room temperature. It has a strain sensitivity of .00002, a gauge length smaller than 1 mm, and no upper limit in a range of strain measurement. In the measurement of high-temperature strain it is free from the need for a dummy gauge and insensitive to an electric drift effect. As examples of strain measurement at high-temperature, thermal expansion and contraction of a top of a soldering iron are measured. The interval of the measurement can be made at shortest 1.6 sec. and the change in the strain is clearly followed until the ultimate stationary temperature is reached.

  14. Validation of perceptual strain index to evaluate the thermal strain in experimental hot conditions

    Habibollah Dehghan

    2015-01-01

    Conclusions: The research findings showed when there is no access to other forms of methods to evaluate the heat stress, it can be used the PeSI in evaluating the strain because of its favorable correlation with the thermal strain.

  15. Characterization of Integrated Optical Strain Sensors Based on Silicon Waveguides

    Westerveld, W.J.; Leinders, S.M.; Muilwijk, P.M.; Pozo, J.

    2013-01-01

    Microscale strain gauges are widely used in micro electro-mechanical systems (MEMS) to measure strains such as those induced by force, acceleration, pressure or sound. We propose all-optical strain sensors based on micro-ring resonators to be integrated with MEMS. We characterized the strain-induced

  16. ON STRAIN RATE SENSITIVITY OF BETA-TITANIUM ALLOYS

    Kobayashi, A.; Takeda, N.; Ogihara, S.; Li, Y.

    1991-01-01

    Ti-15V-3Cr-3A1-3Sn beta-titanium alloys are subjected to 103/s tensile strain rate by the one bar method to investigate strain rate sensitivity. It is found that the ultimate strength, the total elongation and the absorbed energy, all increase with the increase in strain rate. Dynamical stress-strain curves are also obtained.

  17. Generalizing the Fermi velocity of strained graphene from uniform to nonuniform strain

    Oliva-Leyva, M.; Naumis, Gerardo G.

    2015-10-01

    The relevance of the strain-induced Dirac point shift to obtain the appropriate anisotropic Fermi velocity of strained graphene is demonstrated. Then a critical revision of the available effective Dirac Hamiltonians is made by studying in detail the limiting case of a uniform strain. An effective Dirac Hamiltonian for nonuniform strain is thus reported, which takes into account all strain-induced effects: changes in the nearest-neighbor hopping parameters, the reciprocal lattice deformation and the true shift of the Dirac point. Pseudomagnetic fields are thus explained by means of position-dependent Dirac cones, whereas complex gauge fields appear as a consequence of a position-dependent Fermi velocity. Also, position-dependent Fermi velocity effects on the spinor wavefunction are considered for interesting cases of deformations such as flexural modes.

  18. A new strain gage method for measuring the contractile strain ratio of Zircaloy tubing

    An improved strain gage method for determining the contractile strain ratio (CSR) of Zircaloy tubing was developed. The new method consists of a number of load-unload cyclings at approximately 0.2% plastic strain interval. With this method the CSR of Zircaloy-4 tubing could be determined accurately because it was possible to separate the plastic strains from the elastic strain involvement. The CSR values determined by use of the new method were in good agreement with those calculated from conventional post-test manual measurements. The CSR of the tubing was found to decrease with the amount of deformation during testing because of uneven plastic flow in the gage section. A new technique of inscribing gage marks by use of a YAG laser is discussed. (orig.)

  19. Measurement of local values of strains of the briquette by means of special resistance strain gauges

    Rysz, Jozef

    1997-02-01

    Local measurement of the coal briquette strains during its destruction caused by sudden decrease of pressure of gas filling pores is difficult, because of high strain of coal (exceeds 16%), which results in bursting. A special type of an resistance-strain gauge, which is pressed into a defined position during briquette preparation was elaborated. This gauge is deformed just as the surrounding coal. The strain is measured as a difference in resistance of a mixture of coal grains (briquette material) and short, 8 micrometers dia. graphite fibers. A ca. 0.5 mm thick and ca. 1 mm long gauge was prepared. Its initial resistance constituted several hundreds ohms. The resistance vs. strain dependence is not linear but stable enough in time and does not depend on the type of gas filling briquette pores (e.g. CO2 and He).

  20. Strain hardening and ductility of iron: axisymmetric vs. plane strain elongation. Technical progress report

    Langford, G.

    1979-05-01

    The strain hardening of iron at high strains in plane strain elongation (strip drawing) is shown to fall increasngly below that of drawn iron wires at true strains above 2. This makes it unnecessary to invoke shear band formation simultaneously as a strengthening mechanism and as a ductility reducing mechanism in the drawn strip. Rather, shear bands may be a weakening mechanism in all contexts. A set of specimens of interstitial-free iron deformed in three of the four main classifications of deformation symmetry (wire, strip, and chips, representing axisymmetric elongation, plane strain elongation, and pure shear) has been prepared in the form of mechanical test specimens and thin foils for high resolution selected area diffraction. A simple technique for rapid discovery of the <110> axis of foils of strongly textured bcc wire has been worked out.

  1. The asymptomatic bacteriuria Escherichia coli strain 83972 outcompetes uropathogenic E. coli strains in human urine

    Hancock, Viktoria; Ulett, G.C.; Schembri, M.A.;

    2006-01-01

    Escherichia coli is the most common organism associated with asymptomatic bacteriuria (ABU). In contrast to uropathogenic E. coli (UPEC), which causes symptomatic urinary tract infections (UTI), very little is known about the mechanisms by which these strains colonize the human urinary tract. The...... prototype ABU E. coli strain 83972 was originally isolated from a girl who had carried it asymptomatically for 3 years. Deliberate colonization of UTI-susceptible individuals with E. coli 83972 has been used successfully as an alternative approach for the treatment of patients who are refractory to...... conventional therapy. Colonization with strain 83972 appears to prevent infection with UPEC strains in such patients despite the fact that this strain is unable to express the primary adhesins involved in UTI, viz. P and type 1 fimbriae. Here we investigated the growth characteristics of E. coli 83972 in human...

  2. Developments of borehole strain observation outside China

    邱泽华; 石耀霖

    2004-01-01

    Borehole strain observation is playing an increasingly important role in the study on the crustal movements. It hasbeen used by many countries such as China, USA, Japan, Peru, Australia, South Africa, Iceland and Italy, in research fields of plate tectonics, earthquake, volcanic eruption, dam safety, oil field subsidence, mining collapse andso on. Borehole strainmeter has been improved rapidly and tends to get more and more components included inone probe. Based on observations by this kind of instruments, studies on seismic strain step, slow earthquake,earthquake precursor and volcanic eruption forecasting have made remarkable achievements. In the coming years,borehole strain observation is going to become one major geodetic means, together with GPS and InSAR.

  3. Realization of a Strained Atomic Wire Superlattice.

    Song, Inkyung; Goh, Jung Suk; Lee, Sung-Hoon; Jung, Sung Won; Shin, Jin Sung; Yamane, Hiroyuki; Kosugi, Nobuhiro; Yeom, Han Woong

    2015-11-24

    A superlattice of strained Au-Si atomic wires is successfully fabricated on a Si surface. Au atoms are known to incorporate into the stepped Si(111) surface to form a Au-Si atomic wire array with both one-dimensional (1D) metallic and antiferromagnetic atomic chains. At a reduced density of Au, we find a regular array of Au-Si wires in alternation with pristine Si nanoterraces. Pristine Si nanoterraces impose a strain on the neighboring Au-Si wires, which modifies both the band structure of metallic chains and the magnetic property of spin chains. This is an ultimate 1D version of a strained-layer superlattice of semiconductors, defining a direction toward the fine engineering of self-assembled atomic-scale wires. PMID:26446292

  4. Influence of nuclear radiation on strain gauges

    The examination of safety of nuclear reactor components requires strain measurements on parts of constructions while operating and this means when influenced by nuclear radiation. As strain gauges are the most applied devices for strain measurement and very suitable in respect to their handling, the influence of nuclear radiation has been investigated for the first time more than 30 years ago in order to obtain information on the reliability of measuring results in such difficult environmental conditions. Since that time only some papers have been published dealing with the progress in this field of measuring technics. A generally valid statement however could not be obtained yet. The effect of 10 MeV electron irradiation on the specific resistivity has been studied. (orig./HP)

  5. Influence of pellet shapes on sheath strains

    In the quest to reduce cladding strain from power ramps and thereby reduce the incidence of fuel defects, various aspects of pellet geometry have been examined experimentally. In parallel, the ELESTRES code has been developed to calculate the expansion and the hourglassing of fuel pellets. This paper presents the predictions of ELESTRES for the influence of pellet shapes on the pellet expansion, and compares them to measurements from two irradiations involving a total of 23 fuel elements. The experiments covered various combinations of pellet lengths, diameters, central holes, chamfer and dishes. The linear heat ratings ranged from 40 to 70 kW/m, with burnups up to 200 MW.h/kgU. The experiments and the predictions show similar trends for strains. Moreover, the predicted strains are generally within the scatter of experimental data. It is concluded that the code is in general agreement with this data

  6. Antimicrobial properties of indigenous Lactobacillus sakei strain

    Vesković-Moračanin Slavica

    2010-01-01

    Full Text Available The strain I 154 of Lactobacillus sakei has been isolated from traditionally fermented sausages in the course of the realization of the international project (INCO PROJECT No ICA4-CT-2002-10037. This strain exhibited the ability for bacteriocin production. Antimicrobial properties of the isolated bacteriocin (sakacine, its sensibility towards proteolytic enzymes, as well as the effect of increased to high temperatures on its stability have been examined in this work. Semi purified bacteriocin (sakacine has been isolated from bacteriocin - producing strain Lactobacillus sakei I 154 by the method of saturated precipitation with up to 70% ammonium mono-sulphate solution. The activity of isolated sakacine was examined towards Listeria monocytogenes, Staphylococcus aureus and Escherichia coli 0157:H7. Pepsine, Papaine and Proteinase K were used as proteolytic enzymes. The influence of increased and high temperatures on the bacteriocin activity was examined at different temperatures and exposition periods including autoclaving effects.

  7. Surface instabilities during straining of anisotropic materials

    Legarth, Brian Nyvang; Richelsen, Ann Bettina

    2006-01-01

    The development of instabilities in traction-free surfaces is investigated numerically using a unit cell model. Full finite strain analyses are conducted using isotropic as well as anisotropic yield criteria and both plane strain tension and compression are considered. In the load range of tension...... investigated, it is found that isotropic plasticity can only predict surface instabilities if non-associated plastic flow is accounted for. However, for anisotropic plasticity a surface instability is observed for associated plastic flow if the principal axes of anisotropy coincide with the directions...... of principal overall strain. For other orientations surface instabilities are seen when non-associated plastic flow is taken into account. Compared to tension, smaller compressive deformations are needed in order to initiate a surface instability....

  8. Tensile Properties of TWIP Steel at High Strain Rate

    XIONG Rong-gang; FU Ren-yu; SU Yu; LI Qian; WEI Xi-cheng; LI Lin

    2009-01-01

    Tensile tests of TWIP steels of two compositions are performed in the strain rate range of 10-5 -103 s-1.Results indicate that steel 1# does not exhibit TWIP effect but deformation-induced martensitic transformation appears only.There exists TWIP effect in steel 3#.Tensile properties at room temperature are sensitive to strain rate in the studied strain rate ranges.Analysis on the relationship between strain-hardening exponent and strain rates shows that strain-induced martensitic transformation and formation of twins during deformation have significant influence on their strain-hardening behavior.

  9. Comparison of barley stripe mosaic virus strains.

    Hafez, Elsayed E; Abdel Aleem, Engy E; Fattouh, Faiza A

    2008-01-01

    BSMV (barley stripe mosaic virus) particles were obtained in a pure state from infected host plant tissues of Hordeum vulgare. The three genomic parities (alpha, beta and gamma) were amplified by PCR using specific primers for each particle; each was cloned. Partial sequence of the alpha, beta and gamma segments was determined for the Egyptian isolate of barley stripe mosaic virus (BSMV AE1). Alignment of nucleotide sequences with that of other known strains of the virus, BSMV type strains (CV17, ND18 and China), and the generation of phylogenetic trees was performed. A low level of homology was detected comparing 467 bp of the a and 643 bp of the segments to that of the other strains, and thus BSMV alpha and beta segments were in separate clusters. However, 1154 bp of the gamma segments of BSMV AE1 showed a high level of homology especially to strain BSMV ND18, as they both formed a distinct cluster. Northern blotting of pure BSMV AE1 virus and H. vulgare-infected tissue were compared using an alpha ND18 specific probe. Western blotting using antibodies specific for the coat protein (CP) and the triple gene block 1 (TGB1) protein, which are both encoded by the beta ND18 segment, still indicated a high level of similarity between proteins produced by BSMV ND18 and AE1. We suggest that the BSMV AE1 isolate is a distinct strain of BSMV which reflects the genetic evolutionary divergence among BSMV strains and members of the Hordeivirus group. PMID:18533473

  10. Genome sequence of Haemophilus parasuis strain 29755

    Mullins, Michael A.; Register, Karen B.; Bayles, Darrell O; Dyer, David W.; Joanna S Kuehn; Phillips, Gregory J.

    2011-01-01

    Haemophilus parasuis is a member of the family Pasteurellaceae and is the etiologic agent of Glässer’s disease in pigs, a systemic syndrome associated with only a subset of isolates. The genetic basis for virulence and systemic spread of particular H. parasuis isolates is currently unknown. Strain 29755 is an invasive isolate that has long been used in the study of Glässer’s disease. Accordingly, the genome sequence of strain 29755 is of considerable importance to investigators endeavoring to...

  11. Cells as strain-cued automata

    Cox, Brian N.; Snead, Malcolm L.

    2016-02-01

    We argue in favor of representing living cells as automata and review demonstrations that autonomous cells can form patterns by responding to local variations in the strain fields that arise from their individual or collective motions. An autonomous cell's response to strain stimuli is assumed to be effected by internally-generated, internally-powered forces, which generally move the cell in directions other than those implied by external energy gradients. Evidence of cells acting as strain-cued automata have been inferred from patterns observed in nature and from experiments conducted in vitro. Simulations that mimic particular cases of pattern forming share the idealization that cells are assumed to pass information among themselves solely via mechanical boundary conditions, i.e., the tractions and displacements present at their membranes. This assumption opens three mechanisms for pattern formation in large cell populations: wavelike behavior, kinematic feedback in cell motility that can lead to sliding and rotational patterns, and directed migration during invasions. Wavelike behavior among ameloblast cells during amelogenesis (the formation of dental enamel) has been inferred from enamel microstructure, while strain waves in populations of epithelial cells have been observed in vitro. One hypothesized kinematic feedback mechanism, "enhanced shear motility", accounts successfully for the spontaneous formation of layered patterns during amelogenesis in the mouse incisor. Directed migration is exemplified by a theory of invader cells that sense and respond to the strains they themselves create in the host population as they invade it: analysis shows that the strain fields contain positional information that could aid the formation of cell network structures, stabilizing the slender geometry of branches and helping govern the frequency of branch bifurcation and branch coalescence (the formation of closed networks). In simulations of pattern formation in

  12. Development of inkjet printed strain sensors

    Correia, V.; Caparros, C.; Casellas, C.; Francesch, L.; Rocha, J. G.; Lanceros-Mendez, S.

    2013-10-01

    Strain sensors with different architectures, such as single sensors, sensor arrays and a sensor matrix have been developed by inkjet printing technology. Sensors with gauge factors up to 2.48, dimensions of 1.5 mm × 1.8 mm and interdigitated structures with a distance of 30 μm between the finger lines have been achieved based on PeDOT (poly(3,4-ethylenedioxythiophene) and conductive ink. Strain gauges based on silver ink have also been achieved with a gauge factor of 0.35. Performance tests including 1000 mechanical cycles have been successfully carried out for the development of smart prosthesis applications.

  13. Surface strains in iron oxide heterogeneous layer

    Recently the oxidation study at high temperature, have been glance to examine the influence of the surface strains. The samples of the pure iron were oxidized among 850 and 1050 deg C, under argon-water vapor atmosphere. The oxide layer was analyzed by optics and scanning electrons microscopy, and X-ray diffraction. The results showed a heterogeneous layer consisting of three distinct oxides. On the other hand it was possible to observe the presence of the strains on the mentioned layer. (author)

  14. Tensile strain mapping in flat germanium membranes

    Rhead, S. D., E-mail: S.Rhead@warwick.ac.uk; Halpin, J. E.; Myronov, M.; Patchett, D. H.; Allred, P. S.; Wilson, N. R.; Leadley, D. R. [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Shah, V. A. [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Department of Engineering, University of Warwick, Coventry, CV4 7AL (United Kingdom); Kachkanov, V.; Dolbnya, I. P. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE (United Kingdom); Reparaz, J. S. [ICN2 - Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra (Barcelona) (Spain); Sotomayor Torres, C. M. [ICN2 - Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra (Barcelona) (Spain)

    2014-04-28

    Scanning X-ray micro-diffraction has been used as a non-destructive probe of the local crystalline quality of a thin suspended germanium (Ge) membrane. A series of reciprocal space maps were obtained with ∼4 μm spatial resolution, from which detailed information on the strain distribution, thickness, and crystalline tilt of the membrane was obtained. We are able to detect a systematic strain variation across the membranes, but show that this is negligible in the context of using the membranes as platforms for further growth. In addition, we show evidence that the interface and surface quality is improved by suspending the Ge.

  15. Vortex induced strain effects in anisotropic superconductors

    Strain in a superconductor, produced by the normal vortex core, can affect both static and dynamic properties of vortices. It causes an additional vortex-vortex interaction which is long-ranged (∼ 1/r2) as compared with finite but much stronger London interaction in the fields far below Hc2. The energy of this magneto-elastic interaction is calculated within London model. The role of strain effects in forming vortex lattice structure is demonstrated for YBa2Cu3O7

  16. Development of inkjet printed strain sensors

    Strain sensors with different architectures, such as single sensors, sensor arrays and a sensor matrix have been developed by inkjet printing technology. Sensors with gauge factors up to 2.48, dimensions of 1.5 mm × 1.8 mm and interdigitated structures with a distance of 30 μm between the finger lines have been achieved based on PeDOT (poly(3,4-ethylenedioxythiophene) and conductive ink. Strain gauges based on silver ink have also been achieved with a gauge factor of 0.35. Performance tests including 1000 mechanical cycles have been successfully carried out for the development of smart prosthesis applications. (paper)

  17. Tensile strain mapping in flat germanium membranes

    Scanning X-ray micro-diffraction has been used as a non-destructive probe of the local crystalline quality of a thin suspended germanium (Ge) membrane. A series of reciprocal space maps were obtained with ∼4 μm spatial resolution, from which detailed information on the strain distribution, thickness, and crystalline tilt of the membrane was obtained. We are able to detect a systematic strain variation across the membranes, but show that this is negligible in the context of using the membranes as platforms for further growth. In addition, we show evidence that the interface and surface quality is improved by suspending the Ge

  18. Enabling Strain Hardening Simulations with Dislocation Dynamics

    Arsenlis, A; Cai, W

    2006-12-20

    Numerical algorithms for discrete dislocation dynamics simulations are investigated for the purpose of enabling strain hardening simulations of single crystals on massively parallel computers. The algorithms investigated include the /(N) calculation of forces, the equations of motion, time integration, adaptive mesh refinement, the treatment of dislocation core reactions, and the dynamic distribution of work on parallel computers. A simulation integrating all of these algorithmic elements using the Parallel Dislocation Simulator (ParaDiS) code is performed to understand their behavior in concert, and evaluate the overall numerical performance of dislocation dynamics simulations and their ability to accumulate percents of plastic strain.

  19. Forty mouse strain survey of body composition

    Danielle R Reed; Bachmanov, Alexander A.; Tordoff, Michael G.

    2007-01-01

    We measured body weight and composition of ~10 male and ~10 female mice from 40 inbred strains. Body composition was assessed in ~16-wk old mice that had been individually housed and fed a high-carbohydrate, low-fat diet (AIN-76A) for the previous 8 wk. Carcass lean and fat weights were assessed using a PIXIMus II DEXA and confirmed by fat extraction assay. There was a nearly continuous range of body weights, from a strain mean±SE of 11.4±0.2 g (MSM/MsJ) to 39.3±1.8 g (NON/LtJ). The percentag...

  20. Expression of class 5 antigens by meningococcal strains obtained from patients in Brazil and evaluation of two new monoclonal antibodies

    Elizabeth N. De Gaspari

    2001-06-01

    Full Text Available Determining the profile of antigen expression among meningococci is important for epidemiologic surveillance and vaccine development. To this end, two new mouse monoclonal antibodies (MAbs have been derived against Neisseria meningitidis proteins (class 5. The MAbs were reactive against outer membrane antigens and were bactericidal. Selected anti-class 5 MAbs [(5.1-3E6-2; (5.3-3BH4-C7; (5.4-1BG11-C7; (5.5-3DH-F5G9 also 5F1F4-T3(5.c], and the two new monoclonal antibodies C14F10Br2 (5.8 and 7F11B5Br3 (5.9, were then tested against different meningococcal strains, (63 strains of serogroup A, 60 strains of serogroup C (from 1972 to 1974; and 136 strains of serogroup B (from 1992 meningococci. Our results demonstrated that the expression of class 5 proteins in the N. meningitidis B Brazilian strains studied is highly heterogeneous. The serotypes and subtypes of B:4:P1.15, B:4:P1.9, B:4:P1.7, B:4:P1.3, B:4:P1.14, B:4:P1.16, B:4:NT, and B:NT:NT were detected in N. meningitidis B serogroups.The strains C:2a:P1.2 and A:4.21:P1.9 were dominant in the C and A serogroups, respectively. Serogroup B organisms expressed the class 5 epitopes 5.4 (18%, 5.5 (22%, 5.8 (3.6%, 5.9 (8.0% and 5c (38%. Serogroup C expressed class 5 epitopes 5.1 (81%, 5.4 (35%, 5.5 (33% and 5.9 (5.0%; and serogroup A showed reactivity directed at the class 5 protein 5c (47%; and reactivity was present with the new monoclonal antibody, 5.9 (5.5%. We conclude that the two new MAbs are useful in detecting important group B, class 5 antigens, and that a broad selection of serogroup B, class 5 proteins would be required for an effective vaccine based on the class 5 proteins.

  1. Variability among Rhizobium Strains Originating from Nodules of Vicia faba

    van Berkum, P.; Beyene, D; Vera, F. T.; Keyser, H. H.

    1995-01-01

    Rhizobium strains from nodules of Vicia faba were diverse in plasmid content and serology. Results of multilocus gel electrophoresis and restriction fragment length polymorphism indicated several deep chromosomal lineages among the strains. Linkage disequilibrium among the chromosomal types was detected and may have reflected variation of Rhizobium strains in the different geographical locations from which the strains originated. An investigation of pea strains with antibodies prepared agains...

  2. Reliability of PEDOT-PSS Strain Gauge on foam structure

    Chang, Cheng-Ling; Fix, Kayla; Wang, Wei-Chih

    2010-01-01

    Reliability is one important issue in using PEDOT: PSS as a strain gauge for large strain measurements. In our research, PEDOT: PSS strain gauge is fabricated on the polyurethane and porous substrate, which enhances the mechanical property when large strain and cyclic loads are applied to it. Our result shows that with the polyurethane as the substrate adhesion layer, the strain of PEDOT: PSS can go up to 17.7% and stabilize without reference resistance drifting.

  3. A Wireless Strain Sensor Network for Structural Health Monitoring

    Chengyin Liu; Jun Teng; Ning Wu

    2015-01-01

    Structural strain under external environmental loads is one of the main monitoring parameters in structural health monitoring or dynamic tests. This paper presents a wireless strain sensor network (WSSN) design for monitoring structural dynamic strain field. A precision strain sensor board is developed and integrated with the IRIS mote hardware/software platform for multichannel strain gauge signal conditioning and wireless monitoring. Measurement results confirm the sensor’s functionality re...

  4. Two-Dimensional Laser-Speckle Surface-Strain Gauge

    Barranger, John P.; Lant, Christian

    1992-01-01

    Extension of Yamaguchi's laser-speckle surface-strain-gauge method yields data on two-dimensional surface strains in times as short as fractions of second. Laser beams probe rough spot on surface of specimen before and after processing. Changes in speckle pattern of laser light reflected from spot indicative of changes in surface strains during processing. Used to monitor strains and changes in strains induced by hot-forming and subsequent cooling of steel.

  5. GENDER, CUMULATIVE STRAIN AND DEVIANT BEHAVIOR IN TURKEY

    Özbay, Özden

    2013-01-01

     ABSTRACTThe purpose of this study is to explore whether General Strain Theory played a similar role for male and female deviant acts among the youths in Turkey. Data was derived from 974 students at a Turkish public university. The findings indicated that cumulative strain, anger, and criminal and non-criminal copings played similar roles for both males and females. The results questioned General Strain Theory’s gender difference thesis.Keywords: General strain theory, cumulative strain, gen...

  6. Genotypic Diversity among Bacillus cereus and Bacillus thuringiensis Strains

    Carlson, Cathrine Rein; Caugant, Dominique A; Kolstø, Anne-Brit

    1994-01-01

    Twenty-four strains of Bacillus cereus were analyzed by pulsed-field gel electrophoresis (PFGE) and compared with 12 Bacillus thuringiensis strains. In addition, the 36 strains were examined for variation in 15 chromosomal genes encoding enzymes (by multilocus enzyme electrophoresis [MEE]). The genome of each strain had a distinct NotI restriction enzyme digestion profile by PFGE, and the 36 strains could be assigned to 27 multilocus genotypes by MEE. However, neither PFGE nor MEE analysis co...

  7. Design of Monolithic Integrator for Strain-to-Frequency Converter

    Tuan Mohd. Khairi Tuan Mat; Chew Sue Ping; Akram Abdul Azid

    2012-01-01

    Strain-to-Frequency converter (SFC) is a one of the analog conditioner tools that converts any strain signal to the frequency signal. The basic concept of SFC is by detecting any changing of strains, then converting the strain to the voltage signal and converting the voltage signal to the frequency signal. This tool consists of 3 main  components which are strain gauge, differential integrator and comparator. This paper presents the designing and analysis of monolithic integrator that to be u...

  8. Multiple Comparison Analysis of Two New Genomic Sequences of ILTV Strains from China with Other Strains from Different Geographic Regions.

    Zhao, Yan; Kong, Congcong; Wang, Yunfeng

    2015-01-01

    To date, twenty complete genome sequences of ILTV strains have been published in GenBank, including one strain from China, and nineteen strains from Australian and the United States. To investigate the genomic information on ILTVs from different geographic regions, two additional individual complete genome sequences of WG and K317 strains from China were determined. The genomes of WG and K317 strains were 153,505 and 153,639 bp in length, respectively. Alignments performed on the amino acid sequences of the twelve glycoproteins showed that 13 out of 116 mutational sites were present only among the Chinese strain WG and the Australian strains SA2 and A20. The phylogenetic tree analysis suggested that the WG strain established close relationships with the Australian strain SA2. The recombination events were detected and confirmed in different subregions of the WG strain with the sequences of SA2 and K317 strains as parental. In this study, two new complete genome sequences of Chinese ILTV strains were used in comparative analysis with other complete genome sequences of ILTV strains from China, the United States, and Australia. The analysis of genome comparison, phylogenetic trees, and recombination events showed close relationships among the Chinese strain WG and the Australian strains SA2. The information of the two new complete genome sequences from China will help to facilitate the analysis of phylogenetic relationships and the molecular differences among ILTV strains from different geographic regions. PMID:26186451

  9. Mechanical strength model for plastic bonded granular materials at high strain rates and large strains

    Modeling impact events on systems containing plastic bonded explosive materials requires accurate models for stress evolution at high strain rates out to large strains. For example, in the Steven test geometry reactions occur after strains of 0.5 or more are reached for PBX-9501. The morphology of this class of materials and properties of the constituents are briefly described. We then review the viscoelastic behavior observed at small strains for this class of material, and evaluate large strain models used for granular materials such as cap models. Dilatation under shearing deformations of the PBX is experimentally observed and is one of the key features modeled in cap style plasticity theories, together with bulk plastic flow at high pressures. We propose a model that combines viscoelastic behavior at small strains but adds intergranular stresses at larger strains. A procedure using numerical simulations and comparisons with results from flyer plate tests and low rate uniaxial stress tests is used to develop a rough set of constants for PBX-9501. Comparisons with the high rate flyer plate tests demonstrate that the observed characteristic behavior is captured by this viscoelastic based model. copyright 1998 American Institute of Physics

  10. Failure strains and proposed limit strains for an reactor pressure vessel under severe accident conditions

    The local failure strains of essential design elements of a reactor vessel are investigated. The size influence of the structure is of special interest. Typical severe accident conditions including elevated temperatures and dynamic loads are considered. The main part of work consists of test families with specimens under uniaxial and biaxial load. Within one test family the specimen geometry and the load conditions are similar, but the size is varied up to reactor dimensions. Special attention is given to geometries with a hole or a notch causing non-uniform stress and strain distributions typical for the reactor vessel. A key problem is to determine the local failure strain. Here suitable methods had to be developed including the so-called 'vanishing gap method', and the 'forging die method'. They are based on post-test geometrical measurements of the fracture surfaces and reconstructions of the related strain fields using finite element models. The results indicate that stresses versus dimensionless deformations are approximately size independent up to failure for specimens of similar geometry under similar load conditions. Local failure strains could be determined. The values are rather high and size dependent. Statistical evaluation allow the proposal of limit strains which are also size dependent. If these limit strains are not exceeded, the structures will not fracture

  11. Probiotic Potential of Lactobacillus Strains with Antimicrobial Activity against Some Human Pathogenic Strains

    Parisa Shokryazdan

    2014-01-01

    Full Text Available The objective of this study was to isolate, identify, and characterize some lactic acid bacterial strains from human milk, infant feces, and fermented grapes and dates, as potential probiotics with antimicrobial activity against some human pathogenic strains. One hundred and forty bacterial strains were isolated and, after initial identification and a preliminary screening for acid and bile tolerance, nine of the best isolates were selected and further identified using 16 S rRNA gene sequences. The nine selected isolates were then characterized in vitro for their probiotic characteristics and their antimicrobial activities against some human pathogens. Results showed that all nine isolates belonged to the genus Lactobacillus. They were able to tolerate pH 3 for 3 h, 0.3% bile salts for 4 h, and 1.9 mg/mL pancreatic enzymes for 3 h. They exhibited good ability to attach to intestinal epithelial cells and were not resistant to the tested antibiotics. They also showed good antimicrobial activities against the tested pathogenic strains of humans, and most of them exhibited stronger antimicrobial activity than the reference strain L. casei Shirota. Thus, the nine Lactobacillus strains could be considered as potential antimicrobial probiotic strains against human pathogens and should be further studied for their human health benefits.

  12. Development of 1366 K (20000F) strain sensor and biaxial strain transducer for use to 1033 K (14000F)

    The development and evaluation of (a) the Battelle-Columbus Laboratories (BCL) resistance strain gage system for measurement of strains to 1366 K (20000F), and (b) a biaxial strain transducer, utilizing above system, for measurements to 1033 K (14000F) are described. Data are presented which depict pertinent gage and transducer performance characteristics. The paper should be of particular interest to those in need of strain data at temperatures exceeding the limits of commercially available electric resistance strain gages. (orig.)

  13. Network of flexible capacitive strain gauges for the reconstruction of surface strain

    Monitoring of surface strain on mesosurfaces is a difficult task, often impeded by the lack of scalability of conventional sensing systems. A solution is to deploy large networks of flexible strain gauges, a type of large area electronics. The authors have recently proposed a soft elastomeric capacitor (SEC) as an economical skin-type solution for large-scale deployment onto mesosurfaces. The sensing principle is based on a measurable change in the sensor’s capacitance upon strain. In this paper, we study the performance of the sensor at reconstructing surface strain map and deflection shapes. A particular feature of the sensor is that it measures surface strain additively, because it is not utilized within a Wheatstone bridge configuration. An algorithm is proposed to decompose the additive in-plane strain measurements from the SEC into principal components. The algorithm consists of assuming a polynomial shape function, and deriving the strain based on Kirchhoff plate theory. A least-squares estimator (LSE) is used to minimize the error between the assumed model and the SEC signals after the enforcement of boundary conditions. Numerical simulations are conducted on a symmetric rectangular cantilever thin plate under symmetric and asymmetric static loads to demonstrate the accuracy and real-time applicability of the algorithm. The performance of the algorithm is further examined on an asymmetric cantilever laminated thin plate constituted with orthotropic materials mimicking a wind turbine blade, and subjected to a non-stationary wind load. Results from simulations show good performance of the algorithm at reconstructing the surface strain maps for both in-plane principal strain components, and that it can be applied in real time. However, its performance can be improved by strengthening assumptions on boundary conditions. The algorithm exhibits robustness in performance with respect to load and noise in signals, except when most of the sensors’ signals are

  14. Network of flexible capacitive strain gauges for the reconstruction of surface strain

    Wu, Jingzhe; Song, Chunhui; Saleem, Hussam S.; Downey, Austin; Laflamme, Simon

    2015-05-01

    Monitoring of surface strain on mesosurfaces is a difficult task, often impeded by the lack of scalability of conventional sensing systems. A solution is to deploy large networks of flexible strain gauges, a type of large area electronics. The authors have recently proposed a soft elastomeric capacitor (SEC) as an economical skin-type solution for large-scale deployment onto mesosurfaces. The sensing principle is based on a measurable change in the sensor’s capacitance upon strain. In this paper, we study the performance of the sensor at reconstructing surface strain map and deflection shapes. A particular feature of the sensor is that it measures surface strain additively, because it is not utilized within a Wheatstone bridge configuration. An algorithm is proposed to decompose the additive in-plane strain measurements from the SEC into principal components. The algorithm consists of assuming a polynomial shape function, and deriving the strain based on Kirchhoff plate theory. A least-squares estimator (LSE) is used to minimize the error between the assumed model and the SEC signals after the enforcement of boundary conditions. Numerical simulations are conducted on a symmetric rectangular cantilever thin plate under symmetric and asymmetric static loads to demonstrate the accuracy and real-time applicability of the algorithm. The performance of the algorithm is further examined on an asymmetric cantilever laminated thin plate constituted with orthotropic materials mimicking a wind turbine blade, and subjected to a non-stationary wind load. Results from simulations show good performance of the algorithm at reconstructing the surface strain maps for both in-plane principal strain components, and that it can be applied in real time. However, its performance can be improved by strengthening assumptions on boundary conditions. The algorithm exhibits robustness in performance with respect to load and noise in signals, except when most of the sensors’ signals are

  15. Thermal Strain Analysis of Optic Fiber Sensors

    Chih-Ying Huang

    2013-01-01

    Full Text Available An optical fiber sensor surface bonded onto a host structure and subjected to a temperature change is analytically studied in this work. The analysis is developed in order to assess the thermal behavior of an optical fiber sensor designed for measuring the strain in the host structure. For a surface bonded optical fiber sensor, the measuring sensitivity is strongly dependent on the bonding characteristics which include the protective coating, adhesive layer and the bonding length. Thermal stresses can be generated due to a mismatch of thermal expansion coefficients between the optical fiber and host structure. The optical fiber thermal strain induced by the host structure is transferred via the adhesive layer and protective coating. In this investigation, an analytical expression of the thermal strain and stress in the optical fiber is presented. The theoretical predictions are validated using the finite element method. Numerical results show that the thermal strain and stress are linearly dependent on the difference in thermal expansion coefficients between the optical fiber and host structure and independent of the thermal expansion coefficients of the adhesive and coating.

  16. Strain Elastography Evaluation of Rectal Tumors

    Waage, J. E. R.; Rafaelsen, S. R.; Borley, N. R.;

    2015-01-01

    Purpose: Elastography is a promising method for the identification and differentiation of malignant tissue in several organ systems. The primary aim was to evaluate the inter-and intraobserver reproducibility of endorectal strain elastography differentiation of adenomas and adenocarcinomas. The s...

  17. Aligned carbon nanotube sheet piezoresistive strain sensors

    Li, Ang; Bogdanovich, Alexander E.; Bradford, Philip D.

    2015-09-01

    Carbon nanotubes (CNTs) have a unique set of properties that may be useful in the production of next generation structural health monitoring composites. This research introduces a novel CNT based material system for strain and damage sensing applications. An aligned sheet of interconnected CNTs was drawn from a chemical vapor deposition grown CNT array and then bonded to the surface of glass fiber/epoxy composite coupons. Various types of mechanical tests were conducted, accompanied by real-time electrical data acquisition, in order to evaluate the electro-mechanical behavior of the developed sensing material. Specimens were loaded in the longitudinal and transverse CNT sheet orientations to investigate the anisotropy of the piezoresistive effect. The CNT sheets exhibited good sensing stability, linearity, sensitivity and repeatability within a practical strain range; which are crucial sensor features for health monitoring. It was also demonstrated that the CNT orientation in the sheet had a dramatic effect on the sensitivity, thus validating the usefulness of this sensing material for directional strain/damage monitoring. Finally, pre-straining of the CNT sheet sensors was conducted to further enhance the linearity of electro-mechanical response and long-term stability of the sensors during cyclic loading.

  18. Hysteresis loop analysis in cyclically strained materials

    Polák, Jaroslav; Petráš, Roman

    New York : Springer, 2015 - (Altenbach, H.; Brünig, M.), s. 185-205 ISBN 978-3-319-14659-1. - (Advanced Structural Materials) R&D Projects: GA ČR(CZ) GA13-23652S Institutional support: RVO:68081723 Keywords : cyclic plastic straining * hysteresis loop * statistical theory * effective stress * internal stress Subject RIV: JL - Materials Fatigue, Friction Mechanics

  19. On Boreholes and PBO Borehole Strain

    Gladwin, M. T.; Mee, M. W.

    2003-12-01

    Borehole tensor strainmeters (GTSM) installed in Australia and California have established a baseline of data spanning more than twenty years. The current baseline of data allows characterisation of a moderate number of instruments in a range of very different environments in a way which defines reasonable performance expectations for the upcoming PBO deployments. A generic understanding of effects which result from the process of installation of the instrument in a stressed rock mass emerges. This indicates that, provided due allowance is made for experimentally determined borehole recovery effects, the contribution of borehole strain meters more than adequately fills the observational gap between high stability/long term geodetic measurements of strain and strain rates and high resolution/high frequency seismic observations of earth deformation processes. The various strain relief processes associated with the installation procedures and borehole recovery effects associated with pre-existing stress fields will be documented. Procedures for calibration of the total borehole inclusion and for progressive removal of effects due to rock anisotropy and visco-elastic creep of the grout and rock close to the borehole from far field tectonic effects will be defined and illustrated with examples. Observed deviations from these processes will be shown to be small and consistent with otherwise observed or implied fault motions. Full details of these borehole induced processes are, however, difficult to determine in the early years following installation, particularly if there is significant tectonic activity at the time. Once quantified for each site, the effects can be robustly removed from data streams.

  20. Strain Analysis of the de Mattia Test

    Reiter M.

    2010-06-01

    Full Text Available The de Mattia test is a well-known, standardized and widely used method in the rubber industry for characterizing the fatigue behaviour of rubbers. Due to the visual observation and classification of the crack initiated, high data scatter were usually observed in these tests. To improve the quality of the de Mattia test and to support the applicability of the test method in modern design procedures, two novel experimental methods were proposed. Full-field strain analysis experiments using digital image correlation technique were performed and the local strains at the notch tip determined in the first. A global displacement vs. local strain calibration curves makes the design and conduction of strain based Wöhler curves possible. The crack initiation and crack growth is detected by an image analysis system and the crack growth rate was determined in the second method. To gain more insight into the fatigue behaviour of rubbers, these two novel methods were combined and can efficiently be used for characterizing the fatigue behaviour of rubbers.

  1. Strain Analysis of the de Mattia Test

    Feichter, C.; Vezer, S.; Reiter, M.; Major, Z.

    2010-06-01

    The de Mattia test is a well-known, standardized and widely used method in the rubber industry for characterizing the fatigue behaviour of rubbers. Due to the visual observation and classification of the crack initiated, high data scatter were usually observed in these tests. To improve the quality of the de Mattia test and to support the applicability of the test method in modern design procedures, two novel experimental methods were proposed. Full-field strain analysis experiments using digital image correlation technique were performed and the local strains at the notch tip determined in the first. A global displacement vs. local strain calibration curves makes the design and conduction of strain based Wöhler curves possible. The crack initiation and crack growth is detected by an image analysis system and the crack growth rate was determined in the second method. To gain more insight into the fatigue behaviour of rubbers, these two novel methods were combined and can efficiently be used for characterizing the fatigue behaviour of rubbers.

  2. Characterizing large strain crush response of redwood

    Containers for the transportation of hazardous and radioactive materials incorporate redwood in impact limiters. Redwood is an excellent energy absorber, but only the most rudimentary information exists on its crush properties. The objectives of the study were to fill the information gap by collecting triaxial load-deformation data for redwood; to use these data to characterize redwood crush, assess current wood failure theories, provide developments toward a complete stress-strain theory for redwood; and to review the literature on strain-rate effects on redwood crush performance. The load-deformation responses of redwood at temperature conditions corresponding to ambient (70 degrees F), 150 degrees F, and -20 degrees F conditions were measured in approximately 100 confined compression tests for crush levels leading to material densification. Data analysis provided a more complete description of redwood crush performance and a basis for assessing proposed general orthotropic stress-strain relationships for redwood. A review of existing literature indicated that strain-rate effects cause at most a 20 percent increase in crush stress parallel to grain

  3. The Strain Gauge Plethysmograph For Polysomnography

    Vondra, Vlastimil; Kára, T.; Jurák, Pavel

    Brno : Brno University of Technology , 2004, s. 211-213. ISBN 80-214-2633-0. ISSN 1211-412X. [Biosignal 2004 /17./. Brno (CZ), 23.06.2004-25.06.2004] R&D Projects: GA ČR GA102/02/1339 Keywords : Strain Gauge Plethysmograph * Polysomnography Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery

  4. Influence of nuclear radiation on strain gauges

    The influence of nuclear radiation on strain gauges is a superposition of a primary effect (generation of lattice defects resulting in an increase of resistance), a secondary effect (caused by radiation induced diffusion, which - depending on the material and its prior thermodynamic state - leads to a decrease or increase of resistance) and an after-effect (change of resistance after irradiation or between irradiations). The consequences of these effects depend on different parameters with mudual dependencies. Conclusion: Single strain gauges (quarter bridges) should not be used under nuclear radiation; the multitouch of - usually unknown - influence parameters makes a general prediction of the behaviour under radiation practically impossible. Particularly, it is impossible to apply methods such as choice of special materials or pretreatment procedures in order to get strain gauges for high radiation rates. Strain gauges in half-bridge configuration give - under optimum conditions a small difference of two large interfering quantities, which can hardly be estimated. Thus a prognosis of the performance under radiation remains doubtful. With 26 figs., 1 tab

  5. Revisiting the gauge fields of strained graphene

    Iorio, Alfredo; Pais, Pablo

    2015-12-01

    We show that when graphene is only subject to strain, the spin connection gauge field that arises plays no measurable role, but when intrinsic curvature is present and strain is small, spin connection dictates most of the physics. We do so by showing that the Weyl field associated with strain is a pure gauge field and no constraint on the (2 +1 )-dimensional spacetime appears. On the other hand, for constant intrinsic curvature that also gives a pure gauge Weyl field, we find a classical manifestation of a quantum Weyl anomaly, descending from a constrained spacetime. We are in the position to do this because we find the equations that the conformal factor in (2 +1 ) dimensions has to satisfy, which is a nontrivial generalization to (2 +1 ) dimensions of the classic Liouville equation of the differential geometry of surfaces. Finally, we comment on the peculiarities of the only gauge field that can describe strain, the well-known pseudogauge field A1˜u11-u22 and A2˜u12 , and conclude by offering some scenarios in fundamental physics that this peculiar field could help to realize.

  6. Development of Industrial Yeast Platform Strains

    Bergdahl, Basti; Dato, Laura; Förster, Jochen

    2014-01-01

    frequently encounter high substrate concentrations, low pH, high temperatures and various inhibitory compounds originating either from the raw material used or from cellular metabolism. The aim of this research project is to develop robust platform strains of Saccharomyces cerevisiae based on industrial...

  7. High strain-rate magnetoelasticity in Galfenol

    Domann, J. P.; Loeffler, C. M.; Martin, B. E.; Carman, G. P.

    2015-09-01

    This paper presents the experimental measurements of a highly magnetoelastic material (Galfenol) under impact loading. A Split-Hopkinson Pressure Bar was used to generate compressive stress up to 275 MPa at strain rates of either 20/s or 33/s while measuring the stress-strain response and change in magnetic flux density due to magnetoelastic coupling. The average Young's modulus (44.85 GPa) was invariant to strain rate, with instantaneous stiffness ranging from 25 to 55 GPa. A lumped parameters model simulated the measured pickup coil voltages in response to an applied stress pulse. Fitting the model to the experimental data provided the average piezomagnetic coefficient and relative permeability as functions of field strength. The model suggests magnetoelastic coupling is primarily insensitive to strain rates as high as 33/s. Additionally, the lumped parameters model was used to investigate magnetoelastic transducers as potential pulsed power sources. Results show that Galfenol can generate large quantities of instantaneous power (80 MW/m3 ), comparable to explosively driven ferromagnetic pulse generators (500 MW/m3 ). However, this process is much more efficient and can be cyclically carried out in the linear elastic range of the material, in stark contrast with explosively driven pulsed power generators.

  8. Effective stress coefficient for uniaxial strain condition

    Alam, Mohammad Monzurul; Fabricius, Ida Lykke

    2012-01-01

    coefficient from one dimensional rock mechanical deformation. We further investigated the effect of boundary condition on the stress dependency of effective stress coefficient and discussed its application in reservoir study. As stress field in the reservoirs are most unlikely to be hydrostatic, effective...... stress determined under uniaxial strain condition will be more relevant in reservoir studies....

  9. High strain rate behaviour of polypropylene microfoams

    Gómez-del Río, T.; Garrido, M. A.; Rodríguez, J.; Arencón, D.; Martínez, A. B.

    2012-08-01

    Microcellular materials such as polypropylene foams are often used in protective applications and passive safety for packaging (electronic components, aeronautical structures, food, etc.) or personal safety (helmets, knee-pads, etc.). In such applications the foams which are used are often designed to absorb the maximum energy and are generally subjected to severe loadings involving high strain rates. The manufacture process to obtain polymeric microcellular foams is based on the polymer saturation with a supercritical gas, at high temperature and pressure. This method presents several advantages over the conventional injection moulding techniques which make it industrially feasible. However, the effect of processing conditions such as blowing agent, concentration and microfoaming time and/or temperature on the microstructure of the resulting microcellular polymer (density, cell size and geometry) is not yet set up. The compressive mechanical behaviour of several microcellular polypropylene foams has been investigated over a wide range of strain rates (0.001 to 3000 s-1) in order to show the effects of the processing parameters and strain rate on the mechanical properties. High strain rate tests were performed using a Split Hopkinson Pressure Bar apparatus (SHPB). Polypropylene and polyethylene-ethylene block copolymer foams of various densities were considered.

  10. Strain intermittency in shape-memory alloys

    Balandraud, Xavier; Barrera, Noemi; Biscari, Paolo; Grédiac, Michel; Zanzotto, Giovanni

    2015-05-01

    We study experimentally the intermittent progress of the mechanically induced martensitic transformation in a Cu-Al-Be single crystal through a full-field measurement technique: the grid method. We utilize an in-house, specially designed gravity-based device, wherein a system controlled by water pumps applies a perfectly monotonic uniaxial load through very small force increments. The sample exhibits hysteretic superelastic behavior during the forward and reverse cubic-monoclinic transformation, produced by the evolution of the strain field of the phase microstructures. The in-plane linear strain components are measured on the sample surface during the loading cycle, and we characterize the strain intermittency in a number of ways, showing the emergence of power-law behavior for the strain avalanching over almost six decades of magnitude. We also describe the nonstationarity and the asymmetry observed in the forward versus reverse transformation. The present experimental approach, which allows for the monitoring of the reversible martensitic transformation both locally and globally in the crystal, proves useful and enhances our capabilities in the analysis and possible control of transition-related phenomena in shape-memory alloys.

  11. Manipulating fluorescence intensity with mechanical strains

    In this paper we show that the fluorescence of rhodamine 6G (R6G) can be manipulated by applying mechanical strains to gold nanoparticles (GNs) sandwiched in graphene/GNs/polydimethylsiloxane (graphene/GNs/PDMS) structure. The fluorescence intensity of R6G on the graphene/GNs/PDMS sample shows a gradual increase with the mechanical strain. However, the fluorescence intensity of R6G on the graphene/PDMS structure without the GNs buried in between is almost unchanged under the action of the external mechanical strain. Experiment results indicate that the gap distance change between the GNs is the main cause of the fluorescence intensity increase and graphene, as a passivation layer, does not block the energy transfer from R6G to GNs. Compared with that tuning the gap distance between GNs by preparing various GNs samples, applying macroscopic mechanical strain on GNs is a simple way to manipulate the fluorescence intensity of a specific material and brings a new perspective for optoelectronic applications. (paper)

  12. Effective stress coefficient for uniaxial strain condition

    Alam, M.M.; Fabricius, I.L.

    2012-01-01

    coefficient from one dimensional rock mechanical deformation. We further investigated the effect of boundary condition on the stress dependency of effective stress coefficient and discussed its application in reservoir study. As stress field in the reservoirs are most unlikely to be hydrostatic, effective...... stress determined under uniaxial strain condition will be more relevant in reservoir studies. Copyright 2012 ARMA, American Rock Mechanics Association....

  13. Antimicrobial resistance among Brazilian Corynebacterium diphtheriae strains

    Gabriela Andrade Pereira

    2008-08-01

    Full Text Available The increasing problems with multidrug resistance in relation to Corynebacterium, including C. diphtheriae, are examples of challenges confronting many countries. For this reason, Brazilian C. diphtheriae strains were evaluated by the E-Test for their susceptibility to nine antibacterial drugs used in therapy. Resistance (MIC < 0.002; 0.38 µg/ml to penicillin G was found in 14.8% of the strains tested. Although erythromycin (MIC90 0.75 µg/ml and azithromycin (MIC90 0.064 µg/ml were active against C. diphtheriae in this study, 4.2% of the strains showed decreased susceptibility (MIC 1.0 µg/ml to erythromycin. Multiple resistance profiles were determined by the disk diffusion method using 31 antibiotics. Most C. diphtheriae strains (95.74% showed resistance to mupirocin, aztreonam, ceftazidime, and/or oxacillin, ampicillin, penicillin, tetracycline, clindamycin, lincomycin, and erythromycin. This study presents the antimicrobial susceptibility profiles of Brazilian C. diphtheriae isolates. The data are of value to practitioners, and suggest that some concern exists regarding the use of penicillin.

  14. High strain rate behaviour of polypropylene microfoams

    Martínez A.B.

    2012-08-01

    Full Text Available Microcellular materials such as polypropylene foams are often used in protective applications and passive safety for packaging (electronic components, aeronautical structures, food, etc. or personal safety (helmets, knee-pads, etc.. In such applications the foams which are used are often designed to absorb the maximum energy and are generally subjected to severe loadings involving high strain rates. The manufacture process to obtain polymeric microcellular foams is based on the polymer saturation with a supercritical gas, at high temperature and pressure. This method presents several advantages over the conventional injection moulding techniques which make it industrially feasible. However, the effect of processing conditions such as blowing agent, concentration and microfoaming time and/or temperature on the microstructure of the resulting microcellular polymer (density, cell size and geometry is not yet set up. The compressive mechanical behaviour of several microcellular polypropylene foams has been investigated over a wide range of strain rates (0.001 to 3000 s−1 in order to show the effects of the processing parameters and strain rate on the mechanical properties. High strain rate tests were performed using a Split Hopkinson Pressure Bar apparatus (SHPB. Polypropylene and polyethylene-ethylene block copolymer foams of various densities were considered.

  15. Photoacoustic spectroscopy of a neoplastic cell strain

    Photoacoustic spectrum from lyophilized samples of a neoplastic cell strain (human colon adenocarcinoma HCT-8R) has been obtained at room temperature. The spectra present four absorption peaks corresponding to four different chromophores. Work is in progress to identify the absorbing structures

  16. Recent advances in echocardiography: strain and strain rate imaging [version 1; referees: 3 approved

    Oana Mirea

    2016-04-01

    Full Text Available Deformation imaging by echocardiography is a well-established research tool which has been gaining interest from clinical cardiologists since the introduction of speckle tracking. Post-processing of echo images to analyze deformation has become readily available at the fingertips of the user. New parameters such as global longitudinal strain have been shown to provide added diagnostic value, and ongoing efforts of the imaging societies and industry aimed at harmonizing methods will improve the technique further. This review focuses on recent advances in the field of echocardiographic strain and strain rate imaging, and provides an overview on its current and potential future clinical applications.

  17. Strain rate effects for spallation of concrete

    Häussler-Combe Ulrich

    2015-01-01

    Full Text Available Appropriate triaxial constitutive laws are the key for a realistic simulation of high speed dynamics of concrete. The strain rate effect is still an open issue within this context. In particular the question whether it is a material property – which can be covered by rate dependent stress strain relations – or mainly an effect of inertia is still under discussion. Experimental and theoretical investigations of spallation of concrete specimen in a Hopkinson Bar setup may bring some evidence into this question. For this purpose the paper describes the VERD model, a newly developed constitutive law for concrete based on a damage approach with included strain rate effects [1]. In contrast to other approaches the dynamic strength increase is not directly coupled to strain rate values but related to physical mechanisms like the retarded movement of water in capillary systems and delayed microcracking. The constitutive law is fully triaxial and implemented into explicit finite element codes for the investigation of a wide range of concrete structures exposed to impact and explosions. The current setup models spallation experiments with concrete specimen [2]. The results of such experiments are mainly related to the dynamic tensile strength and the crack energy of concrete which may be derived from, e.g., the velocity of spalled concrete fragments. The experimental results are compared to the VERD model and two further constitutive laws implemented in LS-Dyna. The results indicate that both viscosity and retarded damage are required for a realistic description of the material behaviour of concrete exposed to high strain effects [3].

  18. Volumetric Strain Associated with S-waves

    Robiou Du Pont, Y.; Geballe, Z.; Rudolph, M.; Dreger, D. S.; Wang, C.

    2009-12-01

    In a recent study we showed that some groundwater-level oscillations in Taiwan following the 2008 Mw7.9 Wenchuan earthquake in Sichuan, China, occurred with the arrival of S-waves. Such finding is surprising because S-waves are not normally considered to associate with volumetric strain. In this study we examine the hypothesis that part of the S-wave energy is converted to P-waves at the boundary between layers of different elastic properties, such as that between the sedimentary basin and its basement, and the P-waves so generated may cause volumetric strain. Since the field data for testing the hypothesis is lacking, we use simulated seismic waves in western Taiwan in response to the 2008 Wenchuan earthquake. Two models are used in the test: a 5-layered model with the top 2 km consisting of very low velocity and density material to represent a sedimentary basin and a 4-layered model without the sedimentary layer. The simulated seismograms for the 5-layered model show striking similarity with the documented seismograms and show two distinct differences from the 4-layered model in the 60-s window starting with the first S-wave arrival: First, at a period of ~3 s, Rayleigh waves and corresponding volumetric strains occur in the 5-layered model, which are clearly due to the presence of the sedimentary layer but are not the focus of this study. Second, at a period of ~10 s, the radial displacement amplitude in the 5-layered model increases by a factor of 2 and the volumetric strain amplitude increased by a factor of 5 over the respective amplitudes in the 4-layered model, suggesting S-to-P conversion at the sediment-basement boundary. Thus S-to-P conversion may be a viable mechanism for the association of volumetric strain with S-waves.

  19. Characterization of autochthonous Lactobacillus paracasei strains on potential probiotic ability

    Zorica Radulović

    2010-06-01

    Full Text Available Lactic acid bacteria strains isolated from traditional made cheeses constitute a reservoir of unexplored potential in biotechnology. In this study four autochthonous lactobacilli strains, isolated from traditional white brined cheeses and identified as Lactobacillus paracasei (08, 564, 05 and 02, were investigated on potential probiotic ability. The investigation comprised sensitivity to simulated gastrointestinal tract conditions, antimicrobial activity against wide range of pathogens, antibiotic resistance as well as autoaggregation ability. Lactobacillus rhamnosus GG was used as referent strain. Three tested strains grew well in simulated gastrointestinal conditions, but their sensitivity was greater on bile acids and pancreatin compared with pepsin low pH 2.5. The examined strains had different sensitivity to antibiotics, but three strains showed very good antimicrobial activity to pathogens. All strains demonstrated very good autoaggregation ability. For three of four examined strains of Lb. paracasei probiotic potential was similar with referent strain Lb. rhamnosus GG, determined in vitro

  20. The principle of strain reconstruction tomography: Determination of quench strain distribution from diffraction measurements

    The evaluation of residual elastic strain within the bulk of engineering components or natural objects is a challenging task, since in general it requires mapping a six-component tensor quantity in three dimensions. A further challenge concerns the interpretation of finite resolution data in a way that is commensurate and non-contradictory with respect to continuum deformation models. A practical solution for this problem, if it is ever to be found, must include efficient measurement interpretation and data reduction techniques. We describe the principle of strain tomography by high-energy X-ray diffraction, i.e. reconstruction of the higher dimensional distribution of strain within an object from multiple scans in lower dimensions, and illustrate the application of this principle to a simple case of reconstruction of an axisymmetric residual strain state induced in a cylindrical sample by quenching. The underlying principle of the analysis method presented in this paper allows generalisation to more complex situations

  1. The principle of strain reconstruction tomography: Determination of quench strain distribution from diffraction measurements

    Korsunsky, Alexander M. [Department of Engineering Science, University of Oxford, Parks Road, Oxford, Oxon OX1 3PJ (United Kingdom)]. E-mail: alexander.korsunsky@eng.ox.ac.uk; Vorster, Willem J.J. [Department of Engineering Science, University of Oxford, Parks Road, Oxford, Oxon OX1 3PJ (United Kingdom); Zhang, Shu Yan [Department of Engineering Science, University of Oxford, Parks Road, Oxford, Oxon OX1 3PJ (United Kingdom); Dini, Daniele [Department of Engineering Science, University of Oxford, Parks Road, Oxford, Oxon OX1 3PJ (United Kingdom); Latham, David [Department of Engineering Science, University of Oxford, Parks Road, Oxford, Oxon OX1 3PJ (United Kingdom); Golshan, Mina [Synchrotron Radiation Source, Daresbury Laboratory, Keckwick Lane, Warrington WA4 4AD (United Kingdom); Liu, Jian [Department of Chemistry, University of Durham, South Road, Durham DH1 3LE (United Kingdom); Kyriakoglou, Yannis [Rolls-Royce plc, P.O. Box 31, Derby DE24 8BJ (United Kingdom); Walsh, Michael J. [Rolls-Royce plc, P.O. Box 31, Derby DE24 8BJ (United Kingdom)

    2006-05-15

    The evaluation of residual elastic strain within the bulk of engineering components or natural objects is a challenging task, since in general it requires mapping a six-component tensor quantity in three dimensions. A further challenge concerns the interpretation of finite resolution data in a way that is commensurate and non-contradictory with respect to continuum deformation models. A practical solution for this problem, if it is ever to be found, must include efficient measurement interpretation and data reduction techniques. We describe the principle of strain tomography by high-energy X-ray diffraction, i.e. reconstruction of the higher dimensional distribution of strain within an object from multiple scans in lower dimensions, and illustrate the application of this principle to a simple case of reconstruction of an axisymmetric residual strain state induced in a cylindrical sample by quenching. The underlying principle of the analysis method presented in this paper allows generalisation to more complex situations.

  2. Strain-dependent induction of cytokine profiles in the gut by orally administered Lactobacillus strains

    Maassen, C.B.M.; Holten-Neelen, C. van; Balk, F.; Bak-Glashouwer, M.-J.H. den; Leer, R.J.; Laman, J.D.; Boersma, W.J.A.; Claassen, E.

    2000-01-01

    Different Lactobacillus strains are frequently used in consumer food products. In addition, recombinant lactobacilli which contain novel expression vectors can now be used in immunotherapeutic applications such as oral vaccination strategies and in T cell tolerance induction approaches for autoimmun

  3. International Clostridium difficile animal strain collection and large diversity of animal associated strains

    Janezic, Sandra; Zidaric, Valerija; Pardon, Bart;

    2014-01-01

    Background: Clostridium difficile is an important cause of intestinal infections in some animal species and animals might be a reservoir for community associated human infections. Here we describe a collection of animal associated C. difficile strains from 12 countries based on inclusion criteria......; 10 countries). Conclusions: This results show that although PCR ribotype 078 is often reported as the major animal C. difficile type, especially in pigs, the variability of strains in pigs and other animal hosts is substantial. Most common human PCR ribotypes (014/020 and 002) are also among most...... prevalent animal associated C. difficile strains worldwide. The widespread dissemination of toxigenic C. difficile and the considerable overlap in strain distribution between species furthers concerns about interspecies, including zoonotic, transmission of this critically important pathogen....

  4. Chromosomal duplication strains of Aspergillus nidulans and their instability

    Strains of Aspergillus nidulans with chromosomal duplication were obtained after gamma irradiation followed by crossing of the translocated strains with normal strains. From 20 analysed colonies, 12 have shown translocations induced by irradiation. Segregants from four of these translocation strains crossed to normal strains have shown to be unstable although presenting normal morphology. Two segregants were genetically analysed. The first one has shown a duplication of part of linkage groups VIII and the second one presented a duplication of a segment of linkage group V. These new duplication strains in A. nidulans open new perspectives of a more detailed study of the instability phenomenon in this fungus. (Author)

  5. Complete genome sequence of Treponema pallidum strain DAL-1

    Zobaníková, Marie; Mikolka, Pavol; Čejková, Darina; Pospíšilová, Petra; Chen, Lei; Strouhal, Michal; Qin, Xiang; Weinstock, George M.; Šmajs, David

    2012-01-01

    Treponema pallidum strain DAL-1 is a human uncultivable pathogen causing the sexually transmitted disease syphilis. Strain DAL-1 was isolated from the amniotic fluid of a pregnant woman in the secondary stage of syphilis. Here we describe the 1,139,971 bp long genome of T. pallidum strain DAL-1 which was sequenced using two independent sequencing methods (454 pyrosequencing and Illumina). In rabbits, strain DAL-1 replicated better than the T. pallidum strain Nichols. The comparison of the complete DAL-1 genome sequence with the Nichols sequence revealed a list of genetic differences that are potentially responsible for the increased rabbit virulence of the DAL-1 strain. PMID:23449808

  6. Influence of strained drain on performance of ballistic channel devices

    We have studied the performance of ballistic channel diodes with strained channel or drain, based on Monte Carlo simulation. A larger increase in drain current and mean velocity of electrons in the drain region is observed for strained drain diode compared to strained channel diode. This is due to reduction of intervalley scattering and electrons transported with smaller transverse effective mass in the strained drain. This also results in lower heat generation and parasitic resistances in strained drain. We conclude that the strained drain is an efficient way to improve electrical characteristics of devices with ballistic channel. (paper)

  7. Hole doped Dirac states in silicene by biaxial tensile strain

    Kaloni, Thaneshwor P.

    2013-03-11

    The effects of biaxial tensile strain on the structure, electronic states, and mechanical properties of silicene are studied by ab-initio calculations. Our results show that up to 5% strain the Dirac cone remains essentially at the Fermi level, while higher strain induces hole doped Dirac states because of weakened Si–Si bonds. We demonstrate that the silicene lattice is stable up to 17% strain. It is noted that the buckling first decreases with the strain (up to 10%) and then increases again, which is accompanied by a band gap variation. We also calculate the Grüneisen parameter and demonstrate a strain dependence similar to that of graphene.

  8. Molecular characterization of China rabies virus vaccine strain

    Jiao Wenqiang; Yin Xiangping; Li Zhiyong; Lan Xi; Li Xuerui; Tian Xiaoting; Li Baoyu; Yang Bin; Zhang Yun; Liu Jixing

    2011-01-01

    Abstract Background Rabies virus (RV), the agent of rabies, can cause a severe encephalomyelitis in several species of mammals, including humans. As a human rabies vaccine strain employed in China, the genetic knowledge of the aG strain has not been fully studied. The main goal of the present study is to amplify the whole genome of aG strain, and genetic relationships between other vaccine strains and wild strains were analyzed. Results The entire genome of human rabies virus vaccine strain a...

  9. Molecular characterization of China rabies virus vaccine strain

    Jiao, Wenqiang; Yin, Xiangping; Li, Zhiyong; Lan, Xi; Li, Xuerui; Tian, Xiaoting; Li, Baoyu; Yang, Bin; Zhang, Yun; Liu, Jixing

    2011-01-01

    Background Rabies virus (RV), the agent of rabies, can cause a severe encephalomyelitis in several species of mammals, including humans. As a human rabies vaccine strain employed in China, the genetic knowledge of the aG strain has not been fully studied. The main goal of the present study is to amplify the whole genome of aG strain, and genetic relationships between other vaccine strains and wild strains were analyzed. Results The entire genome of human rabies virus vaccine strain aG employe...

  10. A wide extent of inter-strain diversity in virulent and vaccine strains of alphaherpesviruses.

    Moriah L Szpara

    2011-10-01

    Full Text Available Alphaherpesviruses are widespread in the human population, and include herpes simplex virus 1 (HSV-1 and 2, and varicella zoster virus (VZV. These viral pathogens cause epithelial lesions, and then infect the nervous system to cause lifelong latency, reactivation, and spread. A related veterinary herpesvirus, pseudorabies (PRV, causes similar disease in livestock that result in significant economic losses. Vaccines developed for VZV and PRV serve as useful models for the development of an HSV-1 vaccine. We present full genome sequence comparisons of the PRV vaccine strain Bartha, and two virulent PRV isolates, Kaplan and Becker. These genome sequences were determined by high-throughput sequencing and assembly, and present new insights into the attenuation of a mammalian alphaherpesvirus vaccine strain. We find many previously unknown coding differences between PRV Bartha and the virulent strains, including changes to the fusion proteins gH and gB, and over forty other viral proteins. Inter-strain variation in PRV protein sequences is much closer to levels previously observed for HSV-1 than for the highly stable VZV proteome. Almost 20% of the PRV genome contains tandem short sequence repeats (SSRs, a class of nucleic acids motifs whose length-variation has been associated with changes in DNA binding site efficiency, transcriptional regulation, and protein interactions. We find SSRs throughout the herpesvirus family, and provide the first global characterization of SSRs in viruses, both within and between strains. We find SSR length variation between different isolates of PRV and HSV-1, which may provide a new mechanism for phenotypic variation between strains. Finally, we detected a small number of polymorphic bases within each plaque-purified PRV strain, and we characterize the effect of passage and plaque-purification on these polymorphisms. These data add to growing evidence that even plaque-purified stocks of stable DNA viruses exhibit

  11. Screening and Evaluation of Polyhydroxybutyrate-Producing Strains from Indigenous Isolate Cupriavidus taiwanensis Strains

    Om-Murugan Janarthanan; Chi-Wei Lo; Chin-Kuei Huang; Ho-Shing Wu; Yi-Ming Sun; Wei-Chuan Chen; Yu-Hong Wei

    2011-01-01

    Polyhydroxyalkanoate (PHA) is a biodegradable material with many potential biomedical applications, including medical implants and drug delivery. This study developed a system for screening production strains in order to optimize PHA production in Cupriavidus taiwanensis 184, 185, 186, 187, 204, 208, 209 and Pseudomona oleovorans ATCC 29347. In this study, Sudan black B staining, Infrared (IR) and Gas Chromatography (GC) analysis indicated that the best strain for PHA synthesis is C. taiwanen...

  12. Comparative genomic and functional analysis of 100 Lactobacillus rhamnosus strains and their comparison with strain GG

    Douillard, F.P.; Ribbera, A.; Kant, R.; Pietilä, T.E.; Järvinen, H.M.; Messing, M.; Randazzo, C.L.; Paulin, L.; Laine, P.K.; Ritari, J.; Caggia, C.; Lähteinen, T.; Brouns, S.J.J.; Satokari, R.M.; Ossowski, von, I.

    2013-01-01

    Lactobacillus rhamnosus is a lactic acid bacterium that is found in a large variety of ecological habitats, including artisanal and industrial dairy products, the oral cavity, intestinal tract or vagina. To gain insights into the genetic complexity and ecological versatility of the species L. rhamnosus, we examined the genomes and phenotypes of 100 L. rhamnosus strains isolated from diverse sources. The genomes of 100 L. rhamnosus strains were mapped onto the L. rhamnosus GG reference genome....

  13. Comparative Genomic and Functional Analysis of 100 Lactobacillus rhamnosus Strains and Their Comparison with Strain GG

    Douillard, François P.; Ribbera, Angela; Kant, Ravi; Pietilä, Taija E.; Järvinen, Hanna M.; Messing, Marcel; Randazzo, Cinzia L.; Paulin, Lars; Laine, Pia; Ritari, Jarmo; Caggia, Cinzia; Lähteinen, Tanja; Brouns, Stan J. J.; Satokari, Reetta; von Ossowski, Ingemar

    2013-01-01

    Lactobacillus rhamnosus is a lactic acid bacterium that is found in a large variety of ecological habitats, including artisanal and industrial dairy products, the oral cavity, intestinal tract or vagina. To gain insights into the genetic complexity and ecological versatility of the species L. rhamnosus, we examined the genomes and phenotypes of 100 L. rhamnosus strains isolated from diverse sources. The genomes of 100 L. rhamnosus strains were mapped onto the L. rhamnosus GG reference genome....

  14. Metabolomic study of Chilean biomining bacteria Acidithiobacillus ferrooxidans strain Wenelen and Acidithiobacillus thiooxidans strain Licanantay

    Martínez, Patricio; Gálvez, Sebastián; Ohtsuka, Norimasa; Budinich, Marko; Cortés, María Paz; Serpell, Cristián; Nakahigashi, Kenji; Hirayama, Akiyoshi; Tomita, Masaru; Soga, Tomoyoshi; Martínez, Servet; Maass, Alejandro; Parada, Pilar

    2012-01-01

    In this study, we present the first metabolic profiles for two bioleaching bacteria using capillary electrophoresis coupled with mass spectrometry. The bacteria, Acidithiobacillus ferrooxidans strain Wenelen (DSM 16786) and Acidithiobacillus thiooxidans strain Licanantay (DSM 17318), were sampled at different growth phases and on different substrates: the former was grown with iron and sulfur, and the latter with sulfur and chalcopyrite. Metabolic profiles were scored from planktonic and sess...

  15. Internal residual strain mapping in carburized chrome molybdenum steel after quenching by neutron strain scanning

    A hollow circular cylinder specimen with an annular U-notch of chrome molybdenum steel with 0.20 mass% C (SCM420) was carburized in carrier gas and quenched in oil bath. In order to determine the case depth, the specimen was cut off and carbon content and Vickers hardness gradients were measured experimentally near the carburized surface. The residual strain mapping in the interior of carburized cylinder was conducted nondestructively by neutron strain scanning. In this study, the neutron diffraction from Fe-211 plane was used for strain scanning. The neutron wavelength was tuned to 0.1654nm so that diffraction angle became about 90deg. Radial, hoop and axial residual strains were measured by scanning diffracting volume along the axial direction of cylinder specimen. Each residual strain was calculated from lattice spacing change. Unstressed lattice spacing was determined experimentally using reference coupon specimens that were cut from the interior of same carburized cylinder. As a result, the diffraction peak width at half height, FWHM, near the carburized surface was about 3.7 times wider than that of coupon specimens. On the other hand, the most peak widths in the interior equaled to that of coupon specimens. Peak width broadened slightly as the diffracting volume approached the carburized case layer. From the center to the quarter of cylinder specimen, the hoop and axial strains were tensile, and the radial one was compressive in the interior. From the quarter to the edge of the cylinder specimen, the hoop tensile strain increased, radial and axial strains changed to tensile and compressive, respectively. Therefore, the interior of the cylinder specimen was found to be deformed elastically to balance the existence of compressive residual stresses in the carburized case layer. (author)

  16. Differential detection of classical swine fever virus challenge strains in C-strain vaccinated pigs

    Everett, Helen E.; Crudgington, Bentley S; Sosan-Soulé, Olubukola; Crooke, Helen R.

    2014-01-01

    Background Control of classical swine fever (CSF) by vaccination ideally requires that field strain infection can be detected irrespective of the vaccination status of the herd. To inform on the usefulness of molecular tests compatible with genetic Differentiation of Infected from Vaccinated Animals (DIVA) principles when using live-attenuated vaccines, tonsil homogenates from a vaccination-challenge experiment were analyzed using a differential real-time qRT-PCR for the C-strain vaccine or r...

  17. Strain mapping near a triple junction in strained Ni-based alloy using EBSD and biaxial nanogauges

    Clair, A. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS, Universite de Bourgogne, 9 Avenue Alain Savary, BP 47870, 21078 Dijon Cedex (France); Foucault, M.; Calonne, O. [Areva ANP, Centre Technique Departement Corrosion-Chimie, 30 Bd de l' industrie, BP 181, 71205 Le Creusot (France); Lacroute, Y.; Markey, L.; Salazar, M.; Vignal, V. [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS, Universite de Bourgogne, 9 Avenue Alain Savary, BP 47870, 21078 Dijon Cedex (France); Finot, E., E-mail: Eric.Finot@u-bourgogne.fr [Laboratoire Interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS, Universite de Bourgogne, 9 Avenue Alain Savary, BP 47870, 21078 Dijon Cedex (France)

    2011-05-15

    Research highlights: > Surface strains measured using nanogauge were compared to the texture obtained by EBSD. > Statistics of the principal strain discern the grains according to the Schmid factor. > Strain hotspots were localized near a triple junction of alloy 600 under tensile loading. > Asymetrical profile of the GB strains is a criterion for surface cracking initiation. - Abstract: A key element for analyzing the crack initiation in strained polycrystalline alloys is the local quantification of the surface strain distribution according to the grain texture. Using electron backscattered diffraction, the local microstructure was determined to both localize a triple junction and deduce the local Schmid factors. Kernel average misorientation (KAM) was also used to map the areas of defect concentration. The maximum principal strain and the in-plane shear strain were quantified using the biaxial nanogauge. Distortions of the array of nanodots used as spot markers were analyzed near the triple junction. The crystallographic orientation and the surface strain were then investigated both statistically for each grain and locally at the grain boundaries. The superimposition of microstructure and strain maps allows the high strain gradient (reaching 3-fold the applied strain) to be localized at preferential grain boundaries near the triple junction. The Schmid factors and the KAM were compared to the maximum principal strain and the in-plane shear strain respectively. The polycrystalline deformation was attributable first to the rotation of some grains, followed by the elongation of all grains along their preferential activated slip systems.

  18. Creep Strain and Strain Rate Response of 2219 Al Alloy at High Stress Levels

    Taminger, Karen M. B.; Wagner, John A.; Lisagor, W. Barry

    1998-01-01

    As a result of high localized plastic deformation experienced during proof testing in an International Space Station connecting module, a study was undertaken to determine the deformation response of a 2219-T851 roll forging. After prestraining 2219-T851 Al specimens to simulate strains observed during the proof testing, creep tests were conducted in the temperature range from ambient temperature to 107 C (225 F) at stress levels approaching the ultimate tensile strength of 2219-T851 Al. Strain-time histories and strain rate responses were examined. The strain rate response was extremely high initially, but decayed rapidly, spanning as much as five orders of magnitude during primary creep. Select specimens were subjected to incremental step loading and exhibited initial creep rates of similar magnitude for each load step. Although the creep rates decreased quickly at all loads, the creep rates dropped faster and reached lower strain rate levels for lower applied loads. The initial creep rate and creep rate decay associated with primary creep were similar for specimens with and without prestrain; however, prestraining (strain hardening) the specimens, as in the aforementioned proof test, resulted in significantly longer creep life.

  19. Creep strain and strain rate response of 2219 Al alloy at high stress levels

    Taminger, K.M.B.; Wagner, J.A.; Barry Lisagor, W. [National Aeronautics and Space Administration, Hampton, VA (United States). Langley Research Center

    2000-07-01

    As a result of high localized plastic deformation experienced during proof testing in an international space station connecting module, a study was undertaken to determine the deformation response of a 2219-T851 roll forging. After prestraining 2219-T851 Al specimens to simulate strains observed during the proof testing, creep tests were conducted in the temperature range from ambient temperature to 107 C (225 F) at stress levels approaching the ultimate tensile strength of 2219-T851 Al. Strain-time histories and strain rate responses were examined. The strain rate response was extremely high initially, but decayed rapidly, spanning as much as five orders of magnitude during primary creep. Select specimens were subjected to incremental step loading and exhibited initial creep rates of similar magnitude for each load step. Although the creep rates decreased quickly at all loads, the creep rates dropped faster and reached lower strain rate levels for lower applied loads. The initial creep rate and creep rate decay associated with primary creep were similar for specimens with and without prestrain; however, prestraining (strain hardening) the specimens, as in the aforementioned proof test, resulted in significantly longer creep life. (orig.)

  20. Generalizing the Fermi velocity of strained graphene from uniform to nonuniform strain

    Oliva-Leyva, M., E-mail: moliva@fisica.unam.mx [Departamento de Física-Química, Instituto de Física, Universidad Nacional Autónoma de México (UNAM), Apartado Postal 20-364, 01000 México, Distrito Federal (Mexico); Naumis, Gerardo G., E-mail: naumis@fisica.unam.mx [Departamento de Física-Química, Instituto de Física, Universidad Nacional Autónoma de México (UNAM), Apartado Postal 20-364, 01000 México, Distrito Federal (Mexico); School of Physics Astronomy and Computational Sciences, George Mason University, Fairfax, VA 22030 (United States)

    2015-10-23

    The relevance of the strain-induced Dirac point shift to obtain the appropriate anisotropic Fermi velocity of strained graphene is demonstrated. Then a critical revision of the available effective Dirac Hamiltonians is made by studying in detail the limiting case of a uniform strain. An effective Dirac Hamiltonian for nonuniform strain is thus reported, which takes into account all strain-induced effects: changes in the nearest-neighbor hopping parameters, the reciprocal lattice deformation and the true shift of the Dirac point. Pseudomagnetic fields are thus explained by means of position-dependent Dirac cones, whereas complex gauge fields appear as a consequence of a position-dependent Fermi velocity. Also, position-dependent Fermi velocity effects on the spinor wavefunction are considered for interesting cases of deformations such as flexural modes. - Highlights: • The relevance of the strain-induced Dirac point shift to obtain the anisotropic Fermi velocity is shown. • An appropriate expression of the position-dependent Fermi velocity is reported. • A position-dependent Fermi velocity induces an inhomogeneity in the carrier probability density.

  1. Strain and Sex Effects on Productive and Slaughter Performance of Local Egyptian and Canadian Chicken Strains

    A.E. Taha

    2011-12-01

    Full Text Available This experiment was conducted to evaluate the effect of strain and sex on productive performance and slaughter traits of chickens. A total of 1951 one day old chicks of three Canadian dual purpose strains (Shaver A, B and C and two Egyptian strains (Salam and Mandarah were used. Productive performance measured from one day old to 12 weeks of age and slaughter traits were recorded for cocks at 12 weeks of age. Results revealed that strain effect was clear for Shaver C strain for body weight, weight gain, feed consumption. In addition Shaver C had better feed conversion, dressing, fleshing, liver, glycogen, tenderness percentages but recorded the highest percentages for abdominal and total fat content as well as lowest testicular weight of cocks. Shaver B showed higher percentages for blood loss, feather, bones, gizzard and spleen percentages but Shaver A showed the highest percentages for pH content, ashes, color and water holding capacity. Sex effect showed superiority of males over females for body weight allover study period, weight gain during 4, 6, 8, 10 and 12 weeks and feed consumption during 6, 8, 10 and 12 weeks of age, while sex effect was not clear for feed conversion. Shaver C strain had the best averages for most productive and slaughter traits.

  2. Fiber Bragg grating sensors for strain monitoring of steelwork

    Wang, Tao; He, Dawei; Yang, Fan; Wang, Yongsheng

    2009-11-01

    Over the last few years, fiber Bragg grating (FBG) sensors have attracted a lot of interest and they are being used in various applications. This paper describes the FBG sensors used for strain monitoring of bogie and other steelworks. FBG sensors and resistance strain gauges are set on different position of steel girder, and weight is loaded on the steel girder. Strain value of the steel girder can be caught by two kinds of sensors when weight loaded is changed. Result of experiment shows that strain value obtained by resistance strain gauges and FBG sensor is coinciding. There is a linear correlation between value of strain and the weight loaded on the steel girder. FBG sensors with different encapsulations are set on bogie by acrylic plastic materials in order to monitor its dynamic strains. When sinusoidal load with its frequency from 0.15Hz to 2Hz was set on the bogie, FBG sensor system with data sampling rate of 20Hz were used to monitoring the dynamic strains. Strain data caught by FBG sensor system can offer accurate description of dynamic strain, and value of strain provided by FBG sensor suits theoretical values well. The experimental observations show that FBG sensors can be set on steelworks easily, and can monitor both static strain and dynamic strains well.

  3. Systems strategies for developing industrial microbial strains

    Lee, Sang Yup; Kim, Hyun Uk

    2015-01-01

    performance under industrial fermentation conditions. These challenges can be overcome by taking systems approaches through the use of state-of-the-art tools of systems biology, synthetic biology and evolutionary engineering in the context of industrial bioprocess. Major systems metabolic engineering......Industrial strain development requires system-wide engineering and optimization of cellular metabolism while considering industrially relevant fermentation and recovery processes. It can be conceptualized as several strategies, which may be implemented in an iterative fashion and in different...... orders. The key challenges have been the time-, cost- and labor-intensive processes of strain development owing to the difficulties in understanding complex interactions among the metabolic, gene regulatory and signaling networks at the cell level, which are collectively represented as overall system...

  4. A Tunable Strain Sensor Using Nanogranular Metals

    Friedemann Völklein

    2010-11-01

    Full Text Available This paper introduces a new methodology for the fabrication of strain-sensor elements for MEMS and NEMS applications based on the tunneling effect in nano-granular metals. The strain-sensor elements are prepared by the maskless lithography technique of focused electron-beam-induced deposition (FEBID employing the precursor trimethylmethylcyclopentadienyl platinum [MeCpPt(Me3]. We use a cantilever-based deflection technique to determine the sensitivity (gauge factor of the sensor element. We find that its sensitivity depends on the electrical conductivity and can be continuously tuned, either by the thickness of the deposit or by electron-beam irradiation leading to a distinct maximum in the sensitivity. This maximum finds a theoretical rationale in recent advances in the understanding of electronic charge transport in nano-granular metals.

  5. High Strain Rate Characterisation of Composite Materials

    Eriksen, Rasmus Normann Wilken

    -reinforced polymers, were considered, and it was first shown that the loading history controls equilibrium process. Then the High-speed servo-hydraulic test machine was analysed in terms its ability to create a state of constant strain rate in the specimen. The invertible inertial forces in the load train prevented a...... linear elastic specimen to reach a state of constant strain rate before fracture. This was in contrast to ductile materials, which are widely tested with for the High-speed servohydraulic test machine. The development of the analysis and the interpretation of the results, were based on the experience...... from designing and constructing a high-speed servo-hydraulic test machine and by performing a comprehensive test series. The difficulties encountered in the test work could be addressed with the developed analysis. The conclusion was that the High-speed servo-hydraulic test machine is less suited for...

  6. Transfer induced compressive strain in graphene

    Larsen, Martin Benjamin Barbour Spanget; Mackenzie, David; Caridad, Jose;

    2014-01-01

    We have used spatially resolved micro Raman spectroscopy to map the full width at half maximum (FWHM) of the graphene G-band and the 2D and G peak positions, for as-grown graphene on copper catalyst layers, for transferred CVD graphene and for micromechanically exfoliated graphene, in order...... to characterize the effects of a transfer process on graphene properties. Here we use the FWHM(G) as an indicator of the doping level of graphene, and the ratio of the shifts in the 2D and G bands as an indicator of strain. We find that the transfer process introduces an isotropic, spatially uniform, compressive...... strain in graphene, and increases the carrier concentration....

  7. Dynamic strain aging in Haynes 282 superalloy

    Hörnqvist Magnus

    2014-01-01

    Full Text Available Haynes 282 is a newly introduced Ni-based superallony, developed to provide a combination of high-temperature mechanical properties, thermal stability and processability. The present contribution investigates the effect of dynamic strain aging (DSA on the deformation behaviour of Haynes 282 during monotonic and cyclic loading. It is shown that DSA (presumably related to carbon diffusion based on rough estimates of the activation energy completely dominates the development of the stress during cycling at intermediate temperatures, leading to extensive cyclic hardening and serrated yielding. However, no clear effects on the fatigue life or the resulting dislocation structure could be observed. The tensile properties were not severely affected, in spite of the presence of extensive serrated yielding, although a reduction in ductility was observed in the DSA temperature regime. During monotonic loading at lower strain rates indications of an additional DSA mechanism due to substitutional elements were observed.

  8. Chaotic desynchronization of multi-strain diseases

    Schwartz, I B; Cummings, D A T; Billings, L; McCrary, M; Burke, D S; Schwartz, Ira B.; Shaw, Leah B.; Cummings, Derek A. T.; Billings, Lora; Crary, Marie Mc; Burke, Donald S.

    2005-01-01

    Multi-strain diseases are diseases that consist of several strains, or serotypes. The serotypes may interact by antibody-dependent enhancement (ADE), in which infection with a single serotype is asymptomatic, but infection with a second serotype leads to serious illness accompanied by greater infectivity. It has been observed from serotype data of dengue hemorrhagic fever that outbreaks of the four serotypes occur asynchronously. Both autonomous and seasonally driven outbreaks were studied in a model containing ADE. For sufficiently small ADE, the number of infectives of each serotype synchronizes, with outbreaks occurring in phase. When the ADE increases past a threshold, the system becomes chaotic, and infectives of each serotype desynchronize. However, certain groupings of the primary and second ary infectives remain synchronized even in the chaotic regime.

  9. Models for elastic shells with incompatible strains

    Lewicka, Marta; Mahadevan, L.; Pakzad, Mohammad Reza

    2014-01-01

    The three-dimensional shapes of thin lamina such as leaves, flowers, feathers, wings etc, are driven by the differential strain induced by the relative growth. The growth takes place through variations in the Riemannian metric, given on the thin sheet as a function of location in the central plane and also across its thickness. The shape is then a consequence of elastic energy minimization on the frustrated geometrical object. Here we provide a rigorous derivation of the asymptotic theories f...

  10. Strain weakening enables continental plate tectonics

    Gueydan, Frédéric; Précigout, Jacques; Montesi, Laurent G.J.

    2014-01-01

    International audience Much debate exists concerning the strength distribution of the continental lithosphere, how it controls lithosphere-scale strain localization and hence enables plate tectonics. No rheological model proposed to date is comprehensive enough to describe both the weakness of plate boundary and rigid-like behaviour of plate interiors. Here we show that the duality of strength of the lithosphere corresponds to different stages of microstructural evolution. Geological const...

  11. Hydrogen production by recombinant Escherichia coli strains

    Maeda, Toshinari; Sanchez‐Torres, Viviana; Thomas K Wood

    2012-01-01

    Summary The production of hydrogen via microbial biotechnology is an active field of research. Given its ease of manipulation, the best‐studied bacterium Escherichia coli has become a workhorse for enhanced hydrogen production through metabolic engineering, heterologous gene expression, adaptive evolution, and protein engineering. Herein, the utility of E. coli strains to produce hydrogen, via native hydrogenases or heterologous ones, is reviewed. In addition, potential strategies for increas...

  12. Differentiation of Mycoplasma gallisepticum Strains through RFLP

    Luis José Carrión; Rita Baldrich Ferrer; Gloria Consuelo Ramírez Nieto; Víctor Julio Vera Alfonso

    2012-01-01

    Avian mycoplasmosis is a disease that considerably affects the poultry sector, which is reflected in the decrease of the production parameters in fertile and commercial egg laying broilers. Presentation costs are so high that it is impossible for the poultry industry to survive without thinking of its effective control or eradication. There is great interest in the type of M. gallisepticum (Mg) strains, both vaccine and field, which are key aspects to handle the disease, but there is still no...

  13. Plane strain problem in microstretch elastic solid

    Rajneesh Kumar; Ranjit Singh; T K Chadha

    2003-12-01

    The eigenvalue approach is developed for the two-dimensional plane strain problem in a microstretch elastic medium. Applying Laplace and Fourier transforms, an infinite space subjected to a concentrated force is studied. The integral transforms are inverted using a numerical technique to get displacement, force stress, couple stress and first moment, which are also shown graphically. The results of micropolar elasticity are deduced as a special case from the present formulation.

  14. Strain localization analysis using a multiscale model

    FRANZ, Gérald; ABED-MERAIM, Farid; BEN ZINEB, Tarak; LEMOINE, Xavier; Berveiller, Marcel

    2009-01-01

    The development of a relevant constitutive model adapted to sheet metal forming simulations requires an accurate description of the most important sources of anisotropy, i.e. the slip processes, the intragranular substructure changes and the texture development. During plastic deformation of thin metallic sheets, strain-path changes often occur in the material resulting in macroscopic effects. These softening/hardening effects must be correctly predicted because they can significantly influen...

  15. Strain sensors for high field pulse magnets

    Martinez, Christian [Los Alamos National Laboratory; Zheng, Yan [Los Alamos National Laboratory; Easton, Daniel [Los Alamos National Laboratory; Farinholt, Kevin M [Los Alamos National Laboratory; Park, Gyuhae [Los Alamos National Laboratory

    2009-01-01

    In this paper we present an investigation into several strain sensing technologies that are being considered to monitor mechanical deformation within the steel reinforcement shells used in high field pulsed magnets. Such systems generally operate at cryogenic temperatures to mitigate heating issues that are inherent in the coils of nondestructive, high field pulsed magnets. The objective of this preliminary study is to characterize the performance of various strain sensing technologies at liquid nitrogen temperatures (-196 C). Four sensor types are considered in this investigation: fiber Bragg gratings (FBG), resistive foil strain gauges (RFSG), piezoelectric polymers (PVDF), and piezoceramics (PZT). Three operational conditions are considered for each sensor: bond integrity, sensitivity as a function of temperature, and thermal cycling effects. Several experiments were conducted as part of this study, investigating adhesion with various substrate materials (stainless steel, aluminum, and carbon fiber), sensitivity to static (FBG and RFSG) and dynamic (RFSG, PVDF and PZT) load conditions, and sensor diagnostics using PZT sensors. This work has been conducted in collaboration with the National High Magnetic Field Laboratory (NHMFL), and the results of this study will be used to identify the set of sensing technologies that would be best suited for integration within high field pulsed magnets at the NHMFL facility.

  16. Deformation twinning: Influence of strain rate

    Gray, G.T. III

    1993-11-01

    Twins in most crystal structures, including advanced materials such as intermetallics, form more readily as the temperature of deformation is decreased or the rate of deformation is increased. Both parameters lead to the suppression of thermally-activated dislocation processes which can result in stresses high enough to nucleate and grow deformation twins. Under high-strain rate or shock-loading/impact conditions deformation twinning is observed to be promoted even in high stacking fault energy FCC metals and alloys, composites, and ordered intermetallics which normally do not readily deform via twinning. Under such conditions and in particular under the extreme loading rates typical of shock wave deformation the competition between slip and deformation twinning can be examined in detail. In this paper, examples of deformation twinning in the intermetallics TiAl, Ti-48Al-lV and Ni{sub 3}A as well in the cermet Al-B{sub 4}C as a function of strain rate will be presented. Discussion includes: (1) the microstructural and experimental variables influencing twin formation in these systems and twinning topics related to high-strain-rate loading, (2) the high velocity of twin formation, and (3) the influence of deformation twinning on the constitutive response of advanced materials.

  17. Job strain and the risk of stroke

    Fransson, Eleonor I; Nyberg, Solja T; Heikkilä, Katriina;

    2015-01-01

    BACKGROUND AND PURPOSE: Psychosocial stress at work has been proposed to be a risk factor for cardiovascular disease. However, its role as a risk factor for stroke is uncertain. METHODS: We conducted an individual-participant-data meta-analysis of 196 380 males and females from 14 European cohort...... studies to investigate the association between job strain, a measure of work-related stress, and incident stroke. RESULTS: In 1.8 million person-years at risk (mean follow-up 9.2 years), 2023 first-time stroke events were recorded. The age- and sex-adjusted hazard ratio for job strain relative to no job...... strain was 1.24 (95% confidence interval, 1.05;1.47) for ischemic stroke, 1.01 (95% confidence interval, 0.75;1.36) for hemorrhagic stroke, and 1.09 (95% confidence interval, 0.94;1.26) for overall stroke. The association with ischemic stroke was robust to further adjustment for socioeconomic status...

  18. Integrated strain array for cellular mechanobiology studies

    We have developed an integrated strain array for cell culture enabling high-throughput mechano-transduction studies. Biocompatible cell culture chambers were integrated with an acrylic pneumatic compartment and microprocessor-based control system. Each element of the array consists of a deformable membrane supported by a cylindrical pillar within a well. For user-prescribed waveforms, the annular region of the deformable membrane is pulled into the well around the pillar under vacuum, causing the pillar-supported region with cultured cells to be stretched biaxially. The optically clear device and pillar-based mechanism of operation enables imaging on standard laboratory microscopes. Straightforward fabrication utilizes off-the-shelf components, soft lithography techniques in polydimethylsiloxane and laser ablation of acrylic sheets. Proof of compatibility with basic biological assays and standard imaging equipment were accomplished by straining C2C12 skeletal myoblasts on the device for 6 h. At higher strains, cells and actin stress fibers realign with a circumferential preference

  19. Advanced high temperature static strain sensor development

    Hulse, C. O.; Stetson, K. A.; Grant, H. P.; Jameikis, S. M.; Morey, W. W.; Raymondo, P.; Grudkowski, T. W.; Bailey, R. S.

    1986-01-01

    An examination was made into various techniques to be used to measure static strain in gas turbine liners at temperatures up to 1150 K (1600 F). The methods evaluated included thin film and wire resistive devices, optical fibers, surface acoustic waves, the laser speckle technique with a heterodyne readout, optical surface image and reflective approaches and capacitive devices. A preliminary experimental program to develop a thin film capacitive device was dropped because calculations showed that it would be too sensitive to thermal gradients. In a final evaluation program, the laser speckle technique appeared to work well up to 1150 K when it was used through a relatively stagnant air path. The surface guided acoustic wave approach appeared to be interesting but to require too much development effort for the funds available. Efforts to develop a FeCrAl resistive strain gage system were only partially successful and this part of the effort was finally reduced to a characterization study of the properties of the 25 micron diameter FeCrAl (Kanthal A-1) wire. It was concluded that this particular alloy was not suitable for use as the resistive element in a strain gage above about 1000 K.

  20. Shewanella strain isolated from black powder

    Lutterbach, Marcia T.S.; Contador, Luciana S.; Oliveira, Ana Lucia C.; Galvao, Mariana M. [National Institute of Technology (INT), Rio de Janeiro, RJ (Brazil); Pimenta, Gutemberg S. [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    2009-07-01

    Black powder is a term frequently used to refer to residues formed by various types of iron sulfides mixed with contaminants eventually present in the natural gas flow. According to some researchers, the occurrence of black powder in gas pipelines, besides its chemical corrosion origin, can be directly related to the sulfate-reducing bacteria (SRB) metabolism in this environment. A black powder sample was inoculated in a Post gate E medium modified with the addition of thioglycolate. The resulting positive culture was kept in the laboratory for four years until its use. A dilution technique was then performed aiming to isolate an SRB strain. The bacterial strain isolated and identified through DNA sequencing was not an SRB but rather a Shewanella sp. Compared to the sulfate-reducing bacteria group-traditionally considered the foremost responsible for microbially-influenced corrosion (MIC) - Shewanella is a facultative anaerobe and has a versatile metabolism. Shewanella is able to reduce ferric iron and sulfite, oxidize hydrogen gas, and produce hydrogen sulfide; therefore, these bacteria can be responsible for MIC and pit formation. The isolated Shewanella was used in a corrosion experiment, and the corrosion products were characterized by X-ray diffraction, identifying iron sulfides, iron oxides, and sulfur. Our results indicate that the strain isolated, S. putrefaciens, plays a key role in corrosion problems in gas pipelines. (author)

  1. Influence of plastic strain on deformation-induced martensitic transformations

    Perdahcıoğlu, E.S.; Geijselaers, H.J.M.; Groen, M.

    2008-01-01

    The effects of plastic strain on deformation-induced martensitic transformations have been investigated experimentally. Austenitic metastable stainless steel samples were heated to a temperature at which the transformation is suppressed and were plastically strained to different amounts. The resulti

  2. Strain gauge sensitivity improved by using a composite beam

    Silver, R. H.; Kalfayan, S. H.

    1975-01-01

    Composite beam connected to strain gauge and mounted on test specimen is capable of amplifying small strains by factor of 10. Tests indicate that resulting output can be 10 times greater than standard method.

  3. Speak Up! But Don't Strain Your Voice

    ... Home Current Issue Past Issues Hearing Disorders Speak Up! But don't strain your voice Past Issues / ... Noise Exposure / How Loud Is Too Loud? / Speak Up! But don't strain your voice / Medical Mystery: ...

  4. Foodborne outbreak of shigellosis caused by an unusual Shigella strain.

    Huq, I; Alam, A K; Morris, G K; Wathen, G; Merson, M

    1980-01-01

    A family outbreak of foodborne shigellosis caused by an unusual strain of Shigella is described. The strain was a mannitol-positive variant of Shigella dysenteriae and agglutinated in antiserum prepared against provisional serotype 3341-55.

  5. Effects of strain on the Schwinger pair creation in graphene

    Fanbanrai, P. [Department of Physics, Faculty of Science, Kasetsart University, Bangkok 10900 (Thailand); Hutem, A. [Department of Physics, Faculty of Science, Kasetsart University, Bangkok 10900 (Thailand); Physics Division, Faculty of Science and Technology, Phetchabun Rajabhat University, Phetchabun 67000 (Thailand); Boonchui, S., E-mail: fscistb@ku.ac.th [Department of Physics, Faculty of Science, Kasetsart University, Bangkok 10900 (Thailand); Center of Excellence in Forum for Theoretical Science, Chulalongkorn University, Bangkok 10330 (Thailand)

    2015-09-01

    The effects of strain on mechanically deformed graphene are determined by looking at how the strain affects the amplitude of the Schwinger two particle pair state. The influences of the lattice distortions, such as isotropic tensile strain ϵ{sub is}, shear strain ϵ{sub ss}, uniaxial armchair strain ϵ{sub as}, and zigzag strain ϵ{sub zs}, on the photon emission spectrum have been analyzed. We find that the intensities of the emission increases or decreases when compared to those of the unstrained graphene, depending on the type of strain applied. Thus the structure of energy band, the frequencies of the photons and the emission spectrum can be controlled by use of the different strains.

  6. Electronic structure and optic absorption of phosphorene under strain

    Duan, Houjian; Yang, Mou; Wang, Ruiqiang

    2016-07-01

    We studied the electronic structure and optic absorption of phosphorene (monolayer of black phosphorus) under strain. Strain was found to be a powerful tool for the band structure engineering. The in-plane strain in armchair or zigzag direction changes the effective mass components along both directions, while the vertical strain only has significant effect on the effective mass in the armchair direction. The band gap is narrowed by compressive in-plane strain and tensile vertical strain. Under certain strain configurations, the gap is closed and the energy band evolves to the semi-Dirac type: the dispersion is linear in the armchair direction and is gapless quadratic in the zigzag direction. The band-edge optic absorption is completely polarized along the armchair direction, and the polarization rate is reduced when the photon energy increases. Strain not only changes the absorption edge (the smallest photon energy for electron transition), but also the absorption polarization.

  7. Rhodococcus sp. strain TM1 plays a synergistic role in the degradation of piperidine by Mycobacterium sp. strain THO100.

    Kim, Yong-Hak; Kang, Un-Beom; Konishi, Kyoko; Lee, Cheolju

    2006-09-01

    Mycobacterium sp. strain THO100 and Rhodococcus sp. strain TM1 were isolated from a morpholine-containing enrichment culture of activated sewage sludge. Strain THO100, but not strain TM1, was able to degrade alicyclic amines such as morpholine, piperidine, and pyrrolidine. The mixed strains THO100 and TM1 showed a better growth on piperidine as the substrate than the pure strain THO100 because strain TM1 was able to reduce the level of glutaraldehyde (GA) produced during piperidine degradation. GA was toxic to strain THO100 (IC(50) = 28.3 microM) but less toxic to strain TM1 (IC(50) = 215 microM). Strain THO100 possessed constitutive semialdehyde dehydrogenases, namely Sad1 and Sad2, whose activities toward succinic semialdehyde (SSA) were strongly inhibited by GA. The two isozymes were identified as catalase-peroxidase (KatG = Sad1) and semialdehyde dehydrogenase (Sad2) based on mass spectrometric analyses of tryptic peptides and database searches of the partial DNA sequences of their genes. In contrast, strain TM1 containing another constitutive enzyme Gad1 could oxidize both SSA and GA. This study suggested that strain TM1 possessing Gad1 played a synergistic role in reducing the toxic and inhibitory effects of GA produced in the degradation of piperidine by strain THO100. PMID:16832627

  8. Oxytocin and the oxytocin receptor underlie intra-strain, but not inter-strain, social recognition

    Macbeth, Abbe H.; Lee, Heon-Jin; Edds, Jennifer; Young, W. Scott

    2009-01-01

    We studied three lines of oxytocin (Oxt) and oxytocin receptor (Oxtr) knockout (KO) male mice (Oxt−/−, total Oxtr−/−, and partial-forebrain Oxtr (OxtrFB/FB)) with established deficits in social recognition to further refine our understanding of their deficits with regard to stimulus female's strain. We used a modified social discrimination paradigm in which subjects are singly housed only for the duration of the test. Additionally, stimulus females are singly-housed throughout testing and are presented within corrals for rapid comparison of investigation by subject males. Wildtype (WT) males from all three lines discriminated between familiar and novel females of three different strains (C57BL/6, Balb/c, Swiss-Webster). No KO males discriminated between familiar and novel Balb/c or C57BL/6 females. Male Oxt−/− and Oxtr−/− mice, but not OxtrFB/FB mice, discriminated between familiar and novel Swiss-Webster females. As this might indicate a global deficit in individual recognition for OxtrFB/FB males, we examined their ability to discriminate between females from different strains and compared performance with Oxtr−/− males. WT and KO males from both lines were able to distinguish between familiar and novel females from different strains, indicating the social recognition deficit is not universal. Instead, we hypothesize that the Oxtr is involved in “fine” intra-strain recognition, but is less important in “broad” inter-strain recognition. We also present the novel finding of decreased investigation across tests, which is likely an artifact of repeated testing and not due to stimulus female's strain or age of subject males. PMID:19531157

  9. Shear localization and recrystallization in high-strain, high-strain-rate deformation of tantalum

    Tantalum was subjected to high plastic strains (global effective strains between 0 and 3) at high strain rates (>104 s-1) in an axisymmetric plane strain configuration. Tubular specimens, embedded in thick-walled cylinders made of copper, were collapsed quasi-uniformly by explosively-generated energy; this was performed by placing the explosive charge co-axially with the thick-walled cylinder. The high strains achieved generated temperatures which produced significant microstructural change in the material; these strains and temperatures were computed as a function of radial distance from the cylinder axis. The microstructural features observed were: (i) dislocations and elongated dislocation cells (εeffeffeffeff>2.5, T>1000 K). Whereas the post-deformation (static) recrystallization takes place by a migrational mechanism, dynamic recrystallization is the result of the gradual rotation of subgrains coupled with dislocation annihilation. A simple analysis shows that the statically recrystallized grain sizes observed are consistent with predicted values using conventional grain-growth kinetics. The same analysis shows that the deformation time is not sufficient to generate grains of a size compatible with observation (0.1-0.3 μm). A mechanism describing the evolution of the microstructure leading from elongated dislocation cells, to subgrains, and to micrograins is proposed. Grain-scale localization produced by anisotropic plastic flow and localized recovery and recrystallization was observed at the higher plastic strains (εeff>1). Residual tensile 'hoop' stresses are generated near the central hole region upon unloading; this resulted in ductile fracturing along shear localization bands. (orig.)

  10. Psychological Strains and Youth Suicide in Rural China

    Zhang, Jie; Wieczorek, William F.; Conwell, Yeates; Tu, Xin Ming

    2011-01-01

    The strain theory of suicide postulates that suicide is usually preceded by psychological strains. A strain can be a consequence of any of four conflicts: differential values, aspiration and reality, relative deprivation, and lack of coping skills for a crisis. This study, with a blend of psychiatric and social predictors of suicide, identified correlates of suicide that are relevant to Chinese culture and tested the strain theory of suicide with Chinese data. We sampled 392 suicides and 416 ...

  11. Improved Degradation of Monochlorophenols by a Constructed Strain

    Schwien, Uwe; Schmidt, Eberhard

    1982-01-01

    Pseudomonas sp. strain B13, a strain able to degrade 3-chlorobenzoate and, after prolonged adaptation (40 days), 4-chlorophenol, could transfer the ability to degrade chlorocatechols to a recipient, Alcaligenes sp. strain A7, which is able to grow with benzoate and phenol. Representative transconjugants, such as Alcaligenes sp. strain A7-2, were able to utilize all three isomeric chlorophenols; this property was not possessed by the donor or the recipient. The ability to grow readily with 4-c...

  12. Cross protection among Haemophilus parasuis strains in immunized gnotobiotic pigs.

    Miniats, O. P.; Smart, N L; Rosendal, S

    1991-01-01

    In an attempt to establish if cross protection can be induced by different strains of Haemophilus parasuis, three groups of 12 gnotobiotic pigs were immunized each with an aluminum hydroxide adsorbed whole cell bacterin of one of three H. parasuis strains. Two weeks later, four pigs within each vaccinated group were challenged with aerosols of live cultures of each of the three test strains and observed for response. Two virulent strains V1 and V2 protected all the vaccinated pigs, while all ...

  13. Evaluation of Laying Hen Strains for biodynamic Farms

    Zeltner, Esther

    2008-01-01

    In biodynamic and organic agriculture mostly the same strains of laying hens as in conventional agriculture are used. These strains require feed with a high nutrition level to tap the full potential of their genetic. When this feed is not available it may lead to health problems and ethological interferences as well as to a deficiency of performance. In this study, four potential adequate strains are evaluated and compared with a commercial strain using health and ethological parameters as we...

  14. Metamaterial based telemetric strain sensing in different materials

    Melik, Rohat; Unal, Emre; Perkgoz, Nihan Kosku; Puttlitz, Christian; Demir, Hilmi Volkan

    2010-01-01

    We present telemetric sensing of surface strains on different industrial materials using split-ring-resonator based metamaterials. For wireless strain sensing, we utilize metamaterial array architectures for high sensitivity and low nonlinearity-errors in strain sensing. In this work, telemetric strain measurements in three test materials of cast polyamide, derlin and polyamide are performed by observing operating frequency shift under mechanical deformation and these data are compared with c...

  15. Evaluation of local strain evolution from metallic whisker formation

    The evolution of local strain on electrodeposited tin films upon aging has been monitored by digital image correlation (DIC) for the first time. Maps of principal strains adjacent to whisker locations were constructed by comparing pre- and post-growth scanning electron microscopy images. Results showed that the magnitude of the strain gradient plays an important role in whisker growth. DIC visualized the dynamic growth process in which the alteration of strain field has been identified as causing growth of subsequent whiskers.

  16. Estimating Ground Inclination Using Strain Sensors with Fourier Series Representation

    Ulf Holmberg; Wolfgang Svensson

    2010-01-01

    An embedded measurement system for foot orthosis during gait is proposed. Strain gauge sensors were mounted on a foot orthosis to give information about strain in the sagittal plane. The ankle angle of the orthosis was fixed and strain characteristics were therefore changed when walking on slopes. With a Fourier series representation of the strain during a gait cycle, ground angle at different walking speeds and inclinations could be estimated with similar accuracy as previous studies using k...

  17. PHYLOGENETIC STUDY OF SOME STRAINS OF DUNALIELLA

    Duc Tran; Trung Vo; Sixto Portilla; Clifford Louime; Nguyen Doan; Truc Mai; Dat Tran; Trang Ho

    2013-01-01

    Dunaliella strains were isolated from a key site for salt production in Vietnam (Vinh Hao, Binh Thuan province). The strains were identified based on Internal Transcribed Spacer (ITS) markers. The phylogenetic tree revealed these strains belong to the clades of Dunaliella salina and Dunaliella viridis. Results of this study confirm the ubiquitous nature of Dunaliella and suggest that strains of Dunaliella salina might be acquired locally worldwide for the production of beta-carotene. The iden...

  18. Phototrophic oxidation of ferrous iron by a Rhodomicrobium vannielii strain

    Heising, Silke; Schink, Bernhard

    1998-01-01

    Oxidation of ferrous iron was studied with the anaerobic phototrophic bacterial strain BS-1. Based on morphology, substrate utilization patterns, arrangement of intracytoplasmic membranes and the in vivo absorption spectrum, this strain was assigned to the known species Rhodomicrobium vannielii. Also, the type strain of this species oxidized ferrous iron in the light. Phototrophic growth of strain BS-1 with ferrous iron as electron donor was stimulated by the presence of acetate or succinate ...

  19. Strain-induced changes to the electronic structure of germanium

    Tahini, H. A.

    2012-04-17

    Density functional theory calculations (DFT) are used to investigate the strain-induced changes to the electronic structure of biaxially strained (parallel to the (001), (110) and (111) planes) and uniaxially strained (along the [001], [110] and [111] directions) germanium (Ge). It is calculated that a moderate uniaxial strain parallel to the [111] direction can efficiently transform Ge to a direct bandgap material with a bandgap energy useful for technological applications. © 2012 IOP Publishing Ltd.

  20. EVALUATION OF LOCAL STRAIN EVOLUTION FROM METALLIC WHISKER FORMATION

    Hoffman, E.; Lam, P.

    2011-05-11

    Evolution of local strain on electrodeposited tin films upon aging has been monitored by digital image correlation (DIC) for the first time. Maps of principal strains adjacent to whisker locations were constructed via comparing pre- and post-growth scanning electron microscopy (SEM) images. Results showed that the magnitude of the strain gradient plays an important role in whisker growth. DIC visualized the dynamic growth process in which the alteration of strain field has been identified to cause growth of subsequent whiskers.

  1. Antimalarial effect of agmatine on Plasmodium berghei K173 strain

    SURui-Bin; WEIXiao-Li; LIUYin; LIJin

    2003-01-01

    AIM: To study the antimalarial effect of agmatine (Agm) on chloroquine-susceptible Plasmodium berghei K173strain (S strain) and the P berghei K173 resistant strain (R strain). METHODS: The antimalarial effects of Agm onP berghei K173 S strain and R strain were evaluated by Peters 4-d suppression test in mice. RESULTS: Agm(12.5-200 mg/kg,ig,daily) decreased the parasitemia for both P berghei K173 S strain (IC50=139 mg/kg) and Rstrain (IC50=126mg/kg) in mice. Subcutaneous injection (sc) of Agm (5-40mg/kg,tid) showed relatively strongerantimalarial effect than intragastric gavage (IC50=30 mg/kg) in P berghei K 173 S strain. Spermidine antagonized theantimalarial effect of Agm for P berghei K173 S strain and R strain. Agm did not reverse the chloroquine resistanceof P berghei K173 S strain, dl-α-Difluoromethylornithine (DFMO, sc) decreased the parasitemia of P BergheiK173 S strain and this effect was antagonized by spermidine. CONCLUSION: Agm has an antimalarial effect andthe mechanism is related to its inhibition of polyamine synthesis.

  2. Size-effects in plane strain sheet-necking

    Niordson, Christian Frithiof; Redanz, Pia

    2004-01-01

    A finite strain generalization of the strain gradient plasticity theory by Fleck and Hutchinson (J. Mech. Phys. Solids 49 (2001a) 2245) is proposed and used to study size effects in plane strain necking of thin sheets using the finite element method. Both sheets with rigid grips at the ends and...

  3. Size-effects in plane strain sheet-necking

    Niordson, Christian Frithiof; Redanz, Pia

    2003-01-01

    A finite strain generalization of the strain gradient plasticity theory by Fleck and Hutchinson (2001) is proposed and used to study size effects in plane strain necking of thin sheets using the finite element method. Both sheets with rigid grips at the ends and specimens with shear free ends are...

  4. Fabrication and mechanical characterisation of inkjet printed strain gauges

    Visser, H.A.; Balda Irurzun, U.; Akkerman, R.; Sridhar, A.

    2011-01-01

    The present study focuses on printing strain sensors directly on tensile test specimens using inkjet printing technology. This type of strain gauges has the advantage over conventional strain gauges that no glue or carrying platelet is present between the sensor and the surface that should be measur

  5. Differences in taste in button mushroom strains (Agaricus bisporus)

    Baars, J.J.P.; Stijger, I.; Kersten, M.; Sonnenberg, A.S.M.

    2014-01-01

    This report describes the results of a screening of genetically diverse strains of mushroom Agaricus bisporus for differences in taste. Eight different strains were grown on regular commercial compost and casing soil. Two of these strains were also grown on a casing with calcium chloride added to in

  6. The Lewis Strain Gauge Laboratory: Status and plans

    Hobart, Howard F.; Will, Herbert A.

    1985-01-01

    An in-house lab was established for developing, testing, and evaluating high-temperature strain gauges and to aid in in-house applications of high-temperature strain instrumentation. The lab is automated to provide computer control of oven temperatures, imposed strain, and data sampling.

  7. Flexible Bond Wire Capacitive Strain Sensor for Vehicle Tyres.

    Cao, Siyang; Pyatt, Simon; Anthony, Carl J; Kubba, Ammar I; Kubba, Ali E; Olatunbosun, Oluremi

    2016-01-01

    The safety of the driving experience and manoeuvrability of a vehicle can be improved by detecting the strain in tyres. To measure strain accurately in rubber, the strain sensor needs to be flexible so that it does not deform the medium that it is measuring. In this work, a novel flexible bond wire capacitive strain sensor for measuring the strain in tyres is developed, fabricated and calibrated. An array of 25 micron diameter wire bonds in an approximately 8 mm × 8 mm area is built to create an interdigitated structure, which consists of 50 wire loops resulting in 49 capacitor pairs in parallel. Laser machining was used to pattern copper on a flexible printed circuit board PCB to make the bond pads for the wire attachment. The wire array was finally packaged and embedded in polydimethylsiloxane (PDMS), which acts as the structural material that is strained. The capacitance of the device is in a linear like relationship with respect to the strain, which can measure the strain up to at least ±60,000 micro-strain (±6%) with a resolution of ~132 micro-strain (0.013%). In-tyre testing under static loading has shown the ability of the sensor to measure large tyre strains. The technology used for sensor fabrication lends itself to mass production and so the design is considered to be consistent with low cost commercialisable strain sensing technology. PMID:27338402

  8. Genetic variations among Mycoplasma bovis strains isolated from Danish cattle

    Kusiluka, L.J.M.; Kokotovic, Branko; Ojeniyi, B.;

    2000-01-01

    The genetic heterogeneity of Mycoplasma bovis strains isolated in Denmark over a 17-year period was investigated. Forty-two field strains isolated from different geographic locations and specimens, including strains from 21 herds involved in two outbreaks of M. bovis-induced mastitis, and the type...

  9. Biochemical Characterization of Prion Strains in Bank Voles

    Romolo Nonno

    2013-07-01

    Full Text Available Prions exist as different strains exhibiting distinct disease phenotypes. Currently, the identification of prion strains is still based on biological strain typing in rodents. However, it has been shown that prion strains may be associated with distinct PrPSc biochemical types. Taking advantage of the availability of several prion strains adapted to a novel rodent model, the bank vole, we investigated if any prion strain was actually associated with distinctive PrPSc biochemical characteristics and if it was possible to univocally identify strains through PrPSc biochemical phenotypes. We selected six different vole-adapted strains (three human-derived and three animal-derived and analyzed PrPSc from individual voles by epitope mapping of protease resistant core of PrPSc (PrPres and by conformational stability and solubility assay. Overall, we discriminated five out of six prion strains, while two different scrapie strains showed identical PrPSc types. Our results suggest that the biochemical strain typing approach here proposed was highly discriminative, although by itself it did not allow us to identify all prion strains analyzed.

  10. Corrosion induced strain monitoring through fibre optic sensors

    The use of strain sensors is commonplace within civil engineering. Fibre optic strain sensors offer a number of advantages over the current electrical resistance type gauges. In this paper the use of fibre optic strain sensors and electrical resistance gauges to monitor the production of corrosion by-products has been investigated and reported

  11. Longitudinal growth strains in five clones of Eucalyptus tereticornis Sm.

    Pankaj Aggarwal; Shakti Chauhan

    2013-01-01

    We studied the variability in longitudinal growth strains and wood basic density in five-year old trees from five clones (one tree per clone) of Eucalyptus tereticornis.Mean longitudinal growth strain in clones ranged from 466 to 876 μm.There was a significant difference between clones in growth strains and wood basic density.Clone 10 exhibited maximum growth strains and basic density,whereas clone 3 and clone 7 exhibited minimum growth strains and basic density,respectively.Within a tree,the growth strain variation with tree height was high but statistically insignificant while within tree variation in basic density was very small.There was no specific trend in variation in either strain or density within a tree.There was 5%-200% difference in growth strain on opposite sides of the logs.However two strains showed a strong positive correlation.There was a moderate positive association of wood basic density and mean growth strains in logs.The variation around the periphery emphasize the need to measure strain more than one,preferably on opposite sides at the same height,on a tree to know the mean strain level for the purpose of selection of clones.

  12. Draft Genome Sequences of Four Plant Probiotic Bacillus Strains.

    Jeong, Haeyoung; Park, Seung-Hwan; Choi, Soo-Keun

    2016-01-01

    Here, we report the whole-genome sequences of four Bacillus strains that exhibit plant probiotic activities. Three of them are the type strains of Bacillus endophyticus, "Bacillus gaemokensis," and Bacillus trypoxylicola, and the other, Bacillus sp. strain KCTC 13219, should be reclassified into a species belonging to the genus Lysinibacillus. PMID:27174273

  13. Towards quantification of the interplay between strain weakening and strain localisation in granular material

    Ritter, Malte C.; Rosenau, Matthias; Leever, Karen; Oncken, Onno

    2014-05-01

    Strain weakening is the major agent of localisation of deformation into shear zones and faults at various scales in brittle media. Physical analogue models using granular material are especially apt to investigate both phenomena, because they are able to reproduce them without the need of any assumptions concerning the physics behind. Several attempts have been made to quantify either strain weakening (e. g. Lohrmann et al., 2003, using Ring-Shear tests) or strain localisation (e. g. Schrank et al., 2008, using a variation of the classical Riedel-experiment). While Ring-Shear tests yield excellent data on strain weakening through measuring shear stress during localisation, they do not allow monitoring the process of strain localisation in-situ because of experimental inaccessibility of the small scale kinematics. In Riedel-type strike-slip experiments, on the other hand, no direct measurements of shear stresses have been available so far. Furthermore, they contain a strong boundary condition in form of a pre-defined linear discontinuity at the base. This forces the formation of Riedel-Shears, i. e. a complex fault system, that makes it difficult to define strain localisation on single faults. We developed a new experimental set-up, in which the formation of a strike-slip shear zone in granular material is induced using an ndenter with stress and strain monitored at high accuracy and resolution. In a first set of experiments we used a horizontal sand layer indented by a vertical wall. The sand layer is laterally unconfined and rests on low-viscosity silicone oil in order to minimize basal shear strength. Compared to the Riedel experiments, this avoids the boundary condition of a pre-existing basal discontinuity allowing one single, hrough-going shear crack to form and propagate. The indenter moves at a constant rate and is equipped with a force sensor that measures the applied push, which integrates over shear stresses along the fault and the base of the sand pack

  14. Extension of monodimensional fuel performance codes to finite strain analysis using a Lagrangian logarithmic strain framework

    Highlights: • A simple extension of standard monodimensional fuel performance codes to finite strain is proposed. • Efficiency and reliability are demonstrated. • The logarithmic strain frameword proposed by Miehe et al. is introduced and discussed. - Abstract: This paper shows how the Lagrangian logarithmic strain framework proposed by Miehe et al. can be used to extend monodimensional fuel performance codes, written in the framework of the infinitesimal strain theory, to be able to cope with large deformation of the cladding, such as the ones observed in reactivity initiated accidents (RIA) or loss-of-coolant accidents (LOCA). We demonstrate that the changes only concern the mechanical behaviour integration step by a straightforward modification of the strains (inputs) and the stress (result). The proposed procedure has been implemented in the open-source MFront code generator developed within the PLEIADES platform to handle mechanical behaviours. Using the Alcyone performance code, we apply this procedure to a simulation case proposed within the framework of a recent benchmark on fuel performance codes by the OECD/NEA

  15. Extension of monodimensional fuel performance codes to finite strain analysis using a Lagrangian logarithmic strain framework

    Helfer, Thomas

    2015-07-15

    Highlights: • A simple extension of standard monodimensional fuel performance codes to finite strain is proposed. • Efficiency and reliability are demonstrated. • The logarithmic strain frameword proposed by Miehe et al. is introduced and discussed. - Abstract: This paper shows how the Lagrangian logarithmic strain framework proposed by Miehe et al. can be used to extend monodimensional fuel performance codes, written in the framework of the infinitesimal strain theory, to be able to cope with large deformation of the cladding, such as the ones observed in reactivity initiated accidents (RIA) or loss-of-coolant accidents (LOCA). We demonstrate that the changes only concern the mechanical behaviour integration step by a straightforward modification of the strains (inputs) and the stress (result). The proposed procedure has been implemented in the open-source MFront code generator developed within the PLEIADES platform to handle mechanical behaviours. Using the Alcyone performance code, we apply this procedure to a simulation case proposed within the framework of a recent benchmark on fuel performance codes by the OECD/NEA.

  16. THE EFFECT OF DIFFERENT PROBIOTIC STRAINS ON FATTENINTHE EFFECT OF DIFFERENT PROBIOTIC STRAINS ON F

    Cyril Hrnčár

    2013-02-01

    Full Text Available The aim of this work was to verify the effect of different probiotic strains applied through a drinking water source to fattening and carcass parameters of broiler ducks. Fattening experiment was realised in half-operating conditions of experimental basis of Department of Poultry Science and Small Animal Husbandry in three-floor cage technology. Totally 90 broiler duck were divided to three groups. Experimental group 1 (n=30 received probiotic strain Lactobacillus fermentum CCM 7158 with concentration of 1x109 colony forming units (CFU in drinking water daily addition of 0.90 g day 1 to day 56 of fattening. Experimental group 2 (n=30 received probiotic strain Enterococcus faecium M 74 with concentration of 1x109 colony forming units (CFU in drinking water daily addition of 0.45 g day 1 to day 56 of fattening. The control group of birds (n=30 received water without any probiotics. The supplementation of probiotic strains Lactobacillus fermentum and Enterococcus faecium no significant affected (P≥0.05 final body weight, feed consumption and mortality of broiler ducks. From carcass parameters, we recorded statistically significant (P<0.05 reduction in weight of abdominal fat of broiler ducks for application of tested probiotic strains.

  17. Prediction of critical current-bending strain relation of Bi2223 composite tape using residual strain of filaments, load-strain curve and geometry of cross-section

    Ochiai, S., E-mail: shojiro.ochiai@materials.mbox.media.kyoto-u.ac.j [Department of Materials Science and Engineering, Graduate School of Engineering, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501 (Japan); Okuda, H.; Matsubayashi, H.; Mukai, Y.; Shin, J.K.; Iwamoto, S.; Hojo, M. [Department of Materials Science and Engineering, Graduate School of Engineering, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501 (Japan); Sato, M. [Japan Synchrotron-Radiation Research Institute (JASRI), Kohto, Sayo 679-5198 (Japan); Osamura, K. [Research Institute for Applied Sciences, Sakyo-ku, Kyoto 606-8202 (Japan); Mimura, M. [Metal Research Center, Furukawa Electric Co. Ltd., Kiyotaki 500, Nikko 321-1493 (Japan)

    2009-10-15

    A prediction method of the critical current-bending strain relation of the Bi2223 composite tape, which was bent at room temperature and cooled down to 77 K for measurement of critical current, was presented. The present method consisted of (a) measurement of residual strain of Bi2223 filaments at room temperature in the sample length direction by the X-ray diffraction method, (b) estimation of tensile fracture strain of the filaments from the analysis of the load-strain curve at room temperature, (c) measurement of geometrical factors such as the thickness of the sample and shape of the core by observation of the cross-section with optical microscope, and (d) calculation of the critical current as a function of bending strain by using the measured parameters mentioned in (a)-(c). The predicted variation of critical current with bending strain by the present approach described well the experimental one.

  18. Genome sequence of Brucella abortus vaccine strain S19 compared to virulent strains yields candidate virulence genes

    Crasta, Oswald R.; Folkerts, Otto; Fei, Zhangjun; Mane, Shrinivasrao P.; Evans, Clive; Martino-Catt, Susan; Bricker, Betsy; Yu, GongXin; Du, Lei; Sobral, Bruno W.

    2008-01-01

    The Brucella abortus strain S19, a spontaneously attenuated strain, has been used as a vaccine strain in vaccination of cattle against brucellosis for six decades. Despite many studies, the physiological and molecular mechanisms causing the attenuation are not known. We have applied pyrosequencing technology together with conventional sequencing to rapidly and comprehensively determine the complete genome sequence of the attenuated Brucella abortus vaccine strain S19. The main goal of this st...

  19. Genome Sequence of Brucella abortus Vaccine Strain S19 Compared to Virulent Strains Yields Candidate Virulence Genes

    Crasta, Oswald R.; Otto Folkerts; Zhangjun Fei; Mane, Shrinivasrao P.; Clive Evans; Susan Martino-Catt; Betsy Bricker; GongXin Yu; Lei Du; Sobral, Bruno W.

    2008-01-01

    The Brucella abortus strain S19, a spontaneously attenuated strain, has been used as a vaccine strain in vaccination of cattle against brucellosis for six decades. Despite many studies, the physiological and molecular mechanisms causing the attenuation are not known. We have applied pyrosequencing technology together with conventional sequencing to rapidly and comprehensively determine the complete genome sequence of the attenuated Brucella abortus vaccine strain S19. The main goal of this st...

  20. Selective enrichment media bias the types of Salmonella enterica strains isolated from mixed strain cultures and complex enrichment broths.

    Lisa Gorski

    Full Text Available For foodborne outbreak investigations it can be difficult to isolate the relevant strain from food and/or environmental sources. If the sample is contaminated by more than one strain of the pathogen the relevant strain might be missed. In this study mixed cultures of Salmonella enterica were grown in one set of standard enrichment media to see if culture bias patterns emerged. Nineteen strains representing four serogroups and ten serotypes were compared in four-strain mixtures in Salmonella-only and in cattle fecal culture enrichment backgrounds using Salmonella enrichment media. One or more strain(s emerged as dominant in each mixture. No serotype was most fit, but strains of serogroups C2 and E were more likely to dominate enrichment culture mixtures than strains of serogroups B or C1. Different versions of Rappaport-Vassiliadis (RV medium gave different patterns of strain dominance in both Salmonella-only and fecal enrichment culture backgrounds. The fittest strains belonged to serogroups C1, C2, and E, and included strains of S. Infantis, S. Thompson S. Newport, S. 6,8:d:-, and S. Give. Strains of serogroup B, which included serotypes often seen in outbreaks such as S. Typhimurium, S. Saintpaul, and S. Schwarzengrund were less likely to emerge as dominant strains in the mixtures when using standard RV as part of the enrichment. Using a more nutrient-rich version of RV as part of the protocol led to a different pattern of strains emerging, however some were still present in very low numbers in the resulting population. These results indicate that outbreak investigations of food and/or other environmental samples should include multiple enrichment protocols to ensure isolation of target strains of Salmonella.

  1. Swine and Poultry Pathogens: the Complete Genome Sequences of Two Strains of Mycoplasma hyopneumoniae and a Strain of Mycoplasma synoviae†

    Vasconcelos, Ana Tereza R.; Ferreira, Henrique B.; Bizarro, Cristiano V; Sandro L. Bonatto; Carvalho, Marcos O.; Pinto, Paulo M.; Almeida, Darcy F.; Almeida, Luiz G. P.; Almeida, Rosana; Alves-Filho, Leonardo; Assunção, Enedina N.; Azevedo, Vasco A. C.; Maurício R. Bogo; Brigido, Marcelo M.; Brocchi, Marcelo

    2005-01-01

    This work reports the results of analyses of three complete mycoplasma genomes, a pathogenic (7448) and a nonpathogenic (J) strain of the swine pathogen Mycoplasma hyopneumoniae and a strain of the avian pathogen Mycoplasma synoviae; the genome sizes of the three strains were 920,079 bp, 897,405 bp, and 799,476 bp, respectively. These genomes were compared with other sequenced mycoplasma genomes reported in the literature to examine several aspects of mycoplasma evolution. Strain-specific reg...

  2. Revealing differences in metabolic flux distributions between a mutant strain and its parent strain Gluconacetobacter xylinus CGMCC 2955.

    Cheng Zhong

    Full Text Available A better understanding of metabolic fluxes is important for manipulating microbial metabolism toward desired end products, or away from undesirable by-products. A mutant strain, Gluconacetobacter xylinus AX2-16, was obtained by combined chemical mutation of the parent strain (G. xylinus CGMCC 2955 using DEC (diethyl sulfate and LiCl. The highest bacterial cellulose production for this mutant was obtained at about 11.75 g/L, which was an increase of 62% compared with that by the parent strain. In contrast, gluconic acid (the main byproduct concentration was only 5.71 g/L for mutant strain, which was 55.7% lower than that of parent strain. Metabolic flux analysis indicated that 40.1% of the carbon source was transformed to bacterial cellulose in mutant strain, compared with 24.2% for parent strain. Only 32.7% and 4.0% of the carbon source were converted into gluconic acid and acetic acid in mutant strain, compared with 58.5% and 9.5% of that in parent strain. In addition, a higher flux of tricarboxylic acid (TCA cycle was obtained in mutant strain (57.0% compared with parent strain (17.0%. It was also indicated from the flux analysis that more ATP was produced in mutant strain from pentose phosphate pathway (PPP and TCA cycle. The enzymatic activity of succinate dehydrogenase (SDH, which is one of the key enzymes in TCA cycle, was 1.65-fold higher in mutant strain than that in parent strain at the end of culture. It was further validated by the measurement of ATPase that 3.53-6.41 fold higher enzymatic activity was obtained from mutant strain compared with parent strain.

  3. A Comprehensive Test of General Strain Theory: Key Strains, Situational- and Trait-Based Negative Emotions, Conditioning Factors, and Delinquency

    Moon, Byongook; Morash, Merry; McCluskey, Cynthia Perez; Hwang, Hye-Won

    2009-01-01

    Using longitudinal data on South Korean youth, the authors addressed limitations of previous tests of general strain theory (GST), focusing on the relationships among key strains, situational- and trait-based negative emotions, conditioning factors, and delinquency. Eight types of strain previously shown most likely to result in delinquency,…

  4. An Atypical Clostridium Strain Related to the Clostridium botulinum Group III Strain Isolated from a Human Blood Culture

    Bouvet, Philippe; Ruimy, Raymond; Bouchier, Christiane; Faucher, Nathalie; Mazuet, Christelle; Popoff, Michel R.

    2014-01-01

    A nontoxigenic strain isolated from a fatal human case of bacterial sepsis was identified as a Clostridium strain from Clostridium botulinum group III, based on the phenotypic characters and 16S rRNA gene sequence, and was found to be related to the mosaic C. botulinum D/C strain according to a multilocus sequence analysis of 5 housekeeping genes.

  5. Examining the Links between Strain, Situational and Dispositional Anger, and Crime: Further Specifying and Testing General Strain Theory.

    Mazerolle, Paul; Piquero, Alex R.; Capowich, George E.

    2003-01-01

    Explored whether relationships between strain, anger, and deviant outcomes varied when using trait- or situational-based measures of anger, noting whether people with higher trait anger had increased likelihood of experiencing strain, becoming angry from strain, and responding deviantly. Relying on trait-based static indicators of anger was…

  6. Draft Genome Sequence of Bacillus subtilis Strain NKYL29, an Antimicrobial-Peptide-Producing Strain from Soil

    Jiang, Yanbin; Xu, Haijin; Ying LI; Liu, Hongbin; Yu, Lei; Qiao, Mingqiang; Liu, Gang

    2014-01-01

    Bacillus subtilis strain NKYL29 is an antimicrobial-peptide-producing strain isolated from the soil of Ranzhuang Tunnel in Hebei Province, China. Here, we present the draft genome of this strain, which provides the genetic basis for application of the antimicrobial peptide.

  7. Different distribution patterns of ten virulence genes in Legionella reference strains and strains isolated from environmental water and patients.

    Zhan, Xiao-Yong; Hu, Chao-Hui; Zhu, Qing-Yi

    2016-04-01

    Virulence genes are distinct regions of DNA which are present in the genome of pathogenic bacteria and absent in nonpathogenic strains of the same or related species. Virulence genes are frequently associated with bacterial pathogenicity in genus Legionella. In the present study, an assay was performed to detect ten virulence genes, including iraA, iraB, lvrA, lvrB, lvhD, cpxR, cpxA, dotA, icmC and icmD in different pathogenicity islands of 47 Legionella reference strains, 235 environmental strains isolated from water, and 4 clinical strains isolated from the lung tissue of pneumonia patients. The distribution frequencies of these genes in reference or/and environmental L. pneumophila strains were much higher than those in reference non-L. pneumophila or/and environmental non-L. pneumophila strains, respectively. L. pneumophila clinical strains also maintained higher frequencies of these genes compared to four other types of Legionella strains. Distribution frequencies of these genes in reference L. pneumophila strains were similar to those in environmental L. pneumophila strains. In contrast, environmental non-L. pneumophila maintained higher frequencies of these genes compared to those found in reference non-L. pneumophila strains. This study illustrates the association of virulence genes with Legionella pathogenicity and reveals the possible virulence evolution of non-L. pneumophia strains isolated from environmental water. PMID:26757724

  8. Interface strain transfer mechanism and error modification for adhered FBG strain sensor

    Li, Jilong; Zhou, Zhi; Ou, Jinping

    2005-06-01

    The application of adhered FBG strain sensor is affected by interface strain transfer and error modification. In his paper, firstly, based on the characterstics of forces and damage, the fundamental hupotheses are given, and the general expression of interface transferring mechanism is derived. After that, united form of the characteristic value-λ for the general equation is geven for the multi-layer coatings. Finally, according to the error-modified equation of adhered FBG sensor, the relationships the error rate η against the shear modulus and the thckness of the glue are given. With regard to the glue applied in engineering (thickness is from 4mm to 60mm, shear modulus is from 30MPa to 200MPa), the error rate η is about 5~10%, and the correction coefficient k is about 1.05~1.11. Hence, the error modification must be considered when adhered FBG strain sensors are used in civil engineering.

  9. Kinases of two strains of Mycoplasma hyopneumoniae and a strain of Mycoplasma synoviae: an overview

    Alexandre Melo Bailão

    2007-01-01

    Full Text Available Mycoplasma synoviae and Mycoplasma hyopneumoniae are wall-less eubacteria belonging to the class of Mollicutes. These prokaryotes have a reduced genome size and reduced biosynthetic machinery. They cause great losses in animal production. M. synoviae is responsible for an upper respiratory tract disease of chickens and turkeys. M. hyopneumoniae is the causative agent of enzootic pneumonia in pigs. The complete genomes of these organisms showed 17 ORFs encoding kinases in M. synoviae and 15 in each of the M. hyopneumoniae strain. Four kinase genes were restricted to the avian pathogen while three were specific to the pig pathogen when compared to each other. All deduced kinases found in the non pathogenic strain (J[ATCC25934] were also found in the pathogenic M. hyopneumoniae strain. The enzymes were classified in nine families composing five fold groups.

  10. Strain analysis of nonlocal viscoelastic Kelvin bar in tension

    ZHAO Xue-chuan; LEI Yong-jun; ZHOU Jian-ping

    2008-01-01

    Based on viscoelastic Kelvin model and nonlocal relationship of strain and stress, a nonlocal constitutive relationship of viscoelasticity is obtained and the strain response of a bar in tension is studied. By transforming governing equation of the strain analysis into Volterra integration form and by choosing a symmetric exponential form of kernel function and adapting Neumann series, the closed-form solution of strain field of the bar is obtained. The creep process of the bar is presented. When time approaches infinite, the strain of bar is equal to the one of nonlocal elasticity.

  11. Evidence for residual elastic strain in deformed natural quartz

    Kunz, Martin; Chen, Kai; Tamura,Nobumichi; Wenk, Hans-Rudolf

    2009-01-30

    Residual elastic strain in naturally deformed, quartz-containing rocks can be measured quantitatively in a petrographic thin section with high spatial resolution using Laue microdiffraction with white synchrotron x-rays. The measurements with a resolution of one micrometer allow the quantitative determination of the deviatoric strain tensor as a function of position within the crystal investigated. The observed equivalent strain values of 800-1200 microstrains represent a lower bound of the actual preserved residual strain in the rock, since the stress component perpendicular to the cut sample surface plane is released. The measured equivalent strain translates into an equivalent stress in the order of {approx} 50 MPa.

  12. The Cyclic Stress-Strain Curve of Polycrystals

    Pedersen, Ole Bøcker; Rasmussen, K. V.; Winter, A. T.

    1982-01-01

    The internal stresses implied by the Sachs model are estimated for individual PSBs at low plastic strain amplitudes and for homogeneously sheared grains at higher plastic strain amplitudes. The analysis shows that the Sachs model can account semi-quantitatively for experimentally measured cyclic...... stress-strain curves for copper. A similar approximative analysis of the Taylor model cannot account for the data. An interesting feature of the Sachs model is that, although it is assumed that the flow condition is entirely controlled by the PSBs. the predicted cyclic stress-strain curve displays an...... upward slope at high plastic strain amplitudes....

  13. Development of a high temperature static strain gage system

    The objective of this program is to develop electrical resistance strain gages which will permit the measurement of static strains on nickel and cobalt superalloy parts inside gas turbine engines running on a test stand. The specific goal is to develop a complete system able to make strain measurements up to plus or minus 2000 mu strain with a total error of no more than plus or minus 10 percent over a 50 hour period at 1250 K. The initial part of this work consisted of a strain gage alloy development effort in which a variety of alloys were evaluated after being prepared by drop-casting or splat cooling

  14. The dual element method of strain gauge temperature compensation

    Englund, David R.

    1987-01-01

    The use of a known temperature compensation technique is suggested to reduce the overall temperature sensitivity of a PdCr strain gauge system being developed for turbine engine research. The temperature compensation technique proposed for this application uses a resistance thermometer in an adjacent leg of the strain gauge bridge circuit to cancel the thermally generated resistance change of the strain gauge. Equations for calculating the required compensation resistor values and the sensitivity of the resulting strain gauge bridge to both temperature and strain are presented.

  15. Strain-induced softening of glassy and crystalline polymers

    The data on strain-induced softening of glassy and crystalline polymers accompanied by development of the capability of high reversible strains in the samples are analyzed. It is shown that in the first strain cycle, the test sample demonstrates properties typical of glassy or crystalline state, whereas repeated stretching induces transition into a rubber-like high-elasticity state in which the polymer is capable of high reversible strains. It is noted that this transition represents a physical basis of strain-induced softening of glassy and crystalline polymers. The bibliography includes 114 references

  16. Starting in a high strain job…short pain?

    E. VERHOFSTADT; Witte, H; Omey, E.

    2007-01-01

    Karasek (1979) defined a stressful job as a job with an imbalance between the demands of the job and the control one can exercise in that job (a ‘high strain job’). Previous research showed that starters in a high strain job are indeed less satisfied. They are also not compensated for the high workload they face. In this paper, we raise the question whether this strain (‘high strain job’) is only temporary. The results of our duration analysis show that those starting in a high strain job lea...

  17. Strain effects at solid surfaces near the melting point

    Tartaglino, U.; Tosatti, E.

    2002-01-01

    We investigate the effects of strain on a crystal surface close to the bulk melting temperature T_m, where surface melting usually sets in. Strain lowers the bulk melting point, so that at a fixed temperature below but close to T_m the thickness of the quasi-liquid film is expected to grow with strain, irrespective of sign. In addition, a strain-induced solid surface free energy increase/decrease takes place, favoring/disfavoring surface melting depending on the sign of strain relative to sur...

  18. Occurrence and diversity of mosquitocidal strains of Bacillus thuringiensis

    K. Balaraman

    2005-09-01

    Full Text Available Ever since the discovery of the first Bacillus thuringiensis strain capable of killing mosquito larvae,namely, B. thuringiensis var israelensis, there are several reports from different parts of the worldabout the occurrence of mosquitocidal strains belonging to different subspecies/serotypes numberingthirty-six. The main sources of these wild type strains are soils/sediments, plants, animal feces,sick/moribund insects and waters. The toxicity of the strains within a subspecies/serotype variedwidely. Some of the strains exhibited toxicity to mosquitoes as well as lepidopterans and dipterans(including mosquitoes as well as plant parasitic nematodes.

  19. Strain and strain rate by two-dimensional speckle tracking echocardiography in a maned wolf

    Matheus M. Mantovani

    2012-12-01

    Full Text Available The measurement of cardiovascular features of wild animals is important, as is the measurement in pets, for the assessment of myocardial function and the early detection of cardiac abnormalities, which could progress to heart failure. Speckle tracking echocardiography (2D STE is a new tool that has been used in veterinary medicine, which demonstrates several advantages, such as angle independence and the possibility to provide the early diagnosis of myocardial alterations. The aim of this study was to evaluate the left myocardial function in a maned wolf by 2D STE. Thus, the longitudinal, circumferential and radial strain and strain rate were obtained, as well as, the radial and longitudinal velocity and displacement values, from the right parasternal long axis four-chamber view, the left parasternal apical four chamber view and the parasternal short axis at the level of the papillary muscles. The results of the longitudinal variables were -13.52±7.88, -1.60±1.05, 4.34±2.52 and 3.86±3.04 for strain (%, strain rate (1/s, displacement (mm and velocity (cm/s, respectively. In addition, the radial and circumferential Strain and Strain rate were 24.39±14.23, 1.86±0.95 and -13.69±6.53, -1.01±0.48, respectively. Thus, the present study provides the first data regarding the use of this tool in maned wolves, allowing a more complete quantification of myocardial function in this species.

  20. Factors Associated with Strain in Informal Caregivers of Stroke Patients

    Jen-Wen Hung

    2012-10-01

    Full Text Available Background: Stroke is one of the most prevalent causes of adult disability and handicap. Informal caregivers play an important role in poststroke care. However, informal caregivers may experience strain, which threatens the recovery of stroke subjects. This study aimed to describe changes in strain experienced by informal caregivers from 3 to 6 months after the stroke, and identify the predicting factors.Methods: We recruited pairs of inpatients with ischemic stroke and informal caregivers from a tertiary referral hospital and interviewed them at 3 and 6 months after the stroke. Caregiver strain was evaluated using the Caregiver Strain Index (CSI, with a CSI Ÿ 7 indicating considerable caregiver strain. Various factors associated with caregiver strain were analyzed using generalized estimating equations.Results: Eighty-nine stroke patients and caregivers completed the study. Considerable strain was reported in 46% and 43% of the caregivers at the 3rd and 6th month, respectively. Patient factors such as severe disabilities (Barthel Index ŷ 60, poor cognition (Mini-Mental State Examination ŷ 23, depression (Beck Depression Inventory [BDI] Ÿ 10, and recurrent stroke were predictors for caregiver strain. Caregiver factors, such as changed employment status, help from formal caregivers, and depression (BDI Ÿ 10 were also associated with considerable caregiver strain.Conclusions: Nearly 50% of caregivers experienced considerable strain. Interventions aimed at reducing the caregivers’ strain should focus on enhancing the functional and emotional status of stroke subjects, prevention of recurrent stroke, and efficient management of depression symptoms in caregivers.

  1. Historical Evolution of Laboratory Strains of Saccharomyces cerevisiae.

    Louis, Edward J

    2016-01-01

    Budding yeast strains used in the laboratory have had a checkered past. Historically, the choice of strain for any particular experiment depended on the suitability of the strain for the topic of study (e.g., cell cycle vs. meiosis). Many laboratory strains had poor fermentation properties and were not representative of the robust strains used for domestic purposes. Most strains were related to each other, but investigators usually had only vague notions about the extent of their relationships. Isogenicity was difficult to confirm before the advent of molecular genetic techniques. However, their ease of growth and manipulation in laboratory conditions made them "the model" model organism, and they still provided a great deal of fundamental knowledge. Indeed, more than one Nobel Prize has been won using them. Most of these strains continue to be powerful tools, and isogenic derivatives of many of them-including entire collections of deletions, overexpression constructs, and tagged gene products-are now available. Furthermore, many of these strains are now sequenced, providing intimate knowledge of their relationships. Recent collections, new isolates, and the creation of genetically tractable derivatives have expanded the available strains for experiments. But even still, these laboratory strains represent a small fraction of the diversity of yeast. The continued development of new laboratory strains will broaden the potential questions that can be posed. We are now poised to take advantage of this diversity, rather than viewing it as a detriment to controlled experiments. PMID:27371602

  2. Strain-Dependent Norovirus Bioaccumulation in Oysters ▿

    Maalouf, Haifa; Schaeffer, Julien; Parnaudeau, Sylvain; Le Pendu, Jacques; Atmar, Robert L.; Crawford, Sue E.; Le Guyader, Françoise S.

    2011-01-01

    Noroviruses (NoVs) are the main agents of gastroenteritis in humans and the primary pathogens of shellfish-related outbreaks. Some NoV strains bind to shellfish tissues by using carbohydrate structures similar to their human ligands, leading to the hypothesis that such ligands may influence bioaccumulation. This study compares the bioaccumulation efficiencies and tissue distributions in oysters (Crassostrea gigas) of three strains from the two principal human norovirus genogroups. Clear differences between strains were observed. The GI.1 strain was the most efficiently concentrated strain. Bioaccumulation specifically occurred in digestive tissues in a dose-dependent manner, and its efficiency paralleled ligand expression, which was highest during the cold months. In comparison, the GII.4 strain was very poorly bioaccumulated and was recovered in almost all tissues without seasonal influence. The GII.3 strain presented an intermediate behavior, without seasonal effect and with less bioaccumulation efficiency than that of the GI.1 strain during the cold months. In addition, the GII.3 strain was transiently concentrated in gills and mantle before being almost specifically accumulated in digestive tissues. Carbohydrate ligand specificities of the strains at least partly explain the strain-dependent bioaccumulation characteristics. In particular, binding to the digestive-tube-specific ligand should contribute to bioaccumulation, whereas we hypothesize that binding to the sialic acid-containing ligand present in all tissues would contribute to retain virus particles in the gills or mantle and lead to rapid destruction. PMID:21441327

  3. Genotypic Diversity of Haemophilus parasuis Field Strains

    Olvera, A.; Calsamiglia, M.; Aragon, V. (V.)

    2006-01-01

    Haemophilus parasuis is the cause of Glässer's disease and other clinical disorders in pigs. It can also be isolated from the upper respiratory tracts of healthy pigs, and isolates can have significant differences in virulence. In this work, a partial sequence from the 60-kDa heat shock protein (Hsp60) gene was assessed as an epidemiological marker. We analyzed partial sequences of hsp60 and 16S rRNA genes from 103 strains of H. parasuis and other related species to obtain a better classifica...

  4. Isolation of a Bacterium Strain Degraded Agar

    2010-01-01

    One in 58 strains of bacteria isolated from the compost showed clear colonies after a few days of growth on the plates containing medium made of only agar and water.Water suspension contained only agar (2 and 8g·L -1 ) with two controls (normal saline,LB medium) was inoculated with the bacterium BR5-1 to see whether there was an increasement of the alive bacteria concentration after 48 h of the growth.The results showed that there was a significant rising of the alive bacteria concentration in the agar susp...

  5. Weighing of heavy vessels using strain gauges

    The effect of pressure and temperature fluctuations is greatly reduced by appropriate design and by prestressing of the lines in an apparatus for remote, continuous weighing of heavy pressurized vessels (60 bar) at high temperatures (2500C), even when these vessels are connected to other systems by means of metal lines. The weighing device is based on the application of strain gauges. The accuracy of measurement is within 0.5%. Weighing devices of this type can be applied, for example, in the process industry

  6. Laboratory evolution of copper tolerant yeast strains

    Adamo Giusy

    2012-01-01

    Full Text Available Abstract Background Yeast strains endowed with robustness towards copper and/or enriched in intracellular Cu might find application in biotechnology processes, among others in the production of functional foods. Moreover, they can contribute to the study of human diseases related to impairments of copper metabolism. In this study, we investigated the molecular and physiological factors that confer copper tolerance to strains of baker's yeasts. Results We characterized the effects elicited in natural strains of Candida humilis and Saccharomyces cerevisiae by the exposure to copper in the culture broth. We observed that, whereas the growth of Saccharomyces cells was inhibited already at low Cu concentration, C. humilis was naturally robust and tolerated up to 1 g · L-1 CuSO4 in the medium. This resistant strain accumulated over 7 mg of Cu per gram of biomass and escaped severe oxidative stress thanks to high constitutive levels of superoxide dismutase and catalase. Both yeasts were then "evolved" to obtain hyper-resistant cells able to proliferate in high copper medium. While in S. cerevisiae the evolution of robustness towards Cu was paralleled by the increase of antioxidative enzymes, these same activities decreased in evolved hyper-resistant Candida cells. We also characterized in some detail changes in the profile of copper binding proteins, that appeared to be modified by evolution but, again, in a different way in the two yeasts. Conclusions Following evolution, both Candida and Saccharomyces cells were able to proliferate up to 2.5 g · L-1 CuSO4 and to accumulate high amounts of intracellular copper. The comparison of yeasts differing in their robustness, allowed highlighting physiological and molecular determinants of natural and acquired copper tolerance. We observed that different mechanisms contribute to confer metal tolerance: the control of copper uptake, changes in the levels of enzymes involved in oxidative stress response and

  7. Investigation of strain heterogeneities by laser scanning extensometry in strain ageing materials: application to zirconium alloys

    Graff, S.; Forest, S.; Strudel, J.L. [Centre des Materiaux / UMR 7633, Ecole des Mines de Paris / CNRS, BP 87, 91003 Evry (France); Dierke, H.; Neuhauser, H. [Institut fur Physik der Kondensierten Materie, 38106 Braunschweig (Germany); Prioul, C. [MSSMAT, Ecole Centrale Paris, Grande Voie des Vignes, 92295 Chatenay-Malabry (France); Bechade, J.L. [SRMA, CEA Saclay, 91191 Gif sur Yvette (France)

    2005-07-01

    Laser scanning extensometry was used to detect and characterize propagating plastic instabilities such as the Luders bands at the millimeter scale. Spatio-temporal plastic heterogeneities are due to either static or dynamic strain ageing (SSA and DSA) phenomena. Regarding zirconium alloys, different type of heterogeneities were observed: their features strongly depended on mechanical test conditions. In one case, they appeared to be non propagating but preserved along the stress-strain curve and were associated with SSA effects such as stress peaks after relaxation periods or after unloading steps with waiting times. In other case, they appeared as non propagating but were not associated with SSA effects. (authors)

  8. A Review: Carbon Nanotube-Based Piezoresistive Strain Sensors

    Waris Obitayo

    2012-01-01

    Full Text Available The use of carbon nanotubes for piezoresistive strain sensors has acquired significant attention due to its unique electromechanical properties. In this comprehensive review paper, we discussed some important aspects of carbon nanotubes for strain sensing at both the nanoscale and macroscale. Carbon nanotubes undergo changes in their band structures when subjected to mechanical deformations. This phenomenon makes them applicable for strain sensing applications. This paper signifies the type of carbon nanotubes best suitable for piezoresistive strain sensors. The electrical resistivities of carbon nanotube thin film increase linearly with strain, making it an ideal material for a piezoresistive strain sensor. Carbon nanotube composite films, which are usually fabricated by mixing small amounts of single-walled or multiwalled carbon nanotubes with selected polymers, have shown promising characteristics of piezoresistive strain sensors. Studies also show that carbon nanotubes display a stable and predictable voltage response as a function of temperature.

  9. Violent responses to strain: an examination of conditioning influences.

    Mazerolle, P; Piquero, A

    1997-01-01

    Past research on General Strain Theory (GST) has not widely examined the application of the theory for understanding violent responses to strain. Additionally, the theory suggests there may be varying effects of strain on possible deviant outcomes across individuals differentiated on their dispositions toward deviance. In the current analysis, we examine violent responses to strain using original data collected from a sample of college-aged youth. Moreover, we specifically examine whether the effects of strain and anger on possible violent outcomes are invariant across individuals differentiated on their level of exposure to deviant peers and moral constraints against deviance. Using structural equation modeling, our results suggest that a composite measure of strain increases respondents' intentions to engage in assaultive behavior net of other predictors. Additionally, the results reveal that anger mediates the impact of strain on possible violent responses. Finally, the results of our subgroup analyses suggest that the basic form of the GST model is invariant across groups. PMID:9591352

  10. Strain-driven criticality underlies nonlinear mechanics of fibrous networks

    Sharma, A; Rens, R; Vahabi, M; Jansen, K A; Koenderink, G H; MacKintosh, F C

    2016-01-01

    Networks with only central force interactions are floppy when their average connectivity is below an isostatic threshold. Although such networks are mechanically unstable, they can become rigid when strained. It was recently shown that the transition from floppy to rigid states as a function of simple shear strain is continuous, with hallmark signatures of criticality (Nat. Phys. 12, 584 (2016)). The nonlinear mechanical response of collagen networks was shown to be quantitatively described within the framework of such mechanical critical phenomenon. Here, we provide a more quantitative characterization of critical behavior in subisostatic networks. Using finite size scaling we demonstrate the divergence of strain fluctuations in the network at well-defined critical strain. We show that the characteristic strain corresponding to the onset of strain stiffening is distinct from but related to this critical strain in a way that depends on critical exponents. We confirm this prediction experimentally for collagen...

  11. Uniaxial tension test on Rubber at constant true strain rate

    Sourne H.L.

    2012-08-01

    Full Text Available Elastomers are widely used for damping parts in different industrial contexts because of their remarkable dissipation properties. Indeed, they can undergo severe mechanical loading conditions, i.e., high strain rates and large strains. Nevertheless, the mechanical response of these materials can vary from purely rubber-like to glassy depending on the strain rate undergone. Classically, uniaxial tension tests are made in order to find a relation between the stress and the strain in the material at various strain rates. However, even if the strain rate is searched to be constant, it is the nominal strain rate that is considered. Here we develop a test at constant true strain rate, i.e. the strain rate that is experienced by the material. In order to do such a test, the displacement imposed by the machine is an exponential function of time. This test has been performed with a high speed hydraulic machine for strain rates between 0.01/s and 100/s. A specific specimen has been designed, yielding a uniform strain field (and so a uniform stress field. Furthermore, an instrumented aluminum bar has been used to take into account dynamic effects in the measurement of the applied force. A high speed camera enables the determination of strain in the sample using point tracking technique. Using this method, the stress-strain curve of a rubber-like material during a loading-unloading cycle has been determined, up to a stretch ratio λ = 2.5. The influence of the true strain rate both on stiffness and on dissipation of the material is then discussed.

  12. A Methodology for Measuring Strain in Power Semiconductors

    Avery, Seth M.

    The objective of this work is to develop a strain measurement methodology for use in power electronics during electrical operation; such that strain models can be developed and used as the basis of an active strain controller---improving the reliability of power electronics modules. This research involves developing electronic speckle pattern interferometry (ESPI) into a technology capable of measuring thermal-mechanical strain in electrically active power semiconductors. ESPI is a non-contact optical technique capable of high resolution (approx. 10 nm) surface displacement measurements. This work has developed a 3-D ESPI test stand, where simultaneous in- and out-of-plane measured components are combined to accurately determine full-field surface displacement. Two cameras are used to capture both local (interconnect level) displacements and strains, and global (device level) displacements. Methods have been developed to enable strain measurements of larger loads, while avoiding speckle decorrelation (which limits ESPI measurement of large deformations). A method of extracting strain estimates directly from unfiltered and wrapped phase maps has been developed, simplifying data analysis. Experimental noise measurements are made and used to develop optimal filtering using model-based tracking and determined strain noise characteristics. The experimental results of this work are strain measurements made on the surface of a leadframe of an electrically active IGBT. A model-based tracking technique has been developed to allow for the optimal strain solution to be extracted from noisy displacement results. Also, an experimentally validated thermal-mechanical FE strain model has been developed. The results of this work demonstrate that in situ strain measurements in power devices are feasible. Using the procedures developed in the work, strain measurements at critical locations of strain, which limit device reliability, at relevant power levels can be completed.

  13. Two-dimensional surface strain measurement based on a variation of Yamaguchi's laser-speckle strain gauge

    Barranger, John P.

    1990-01-01

    A novel optical method of measuring 2-D surface strain is proposed. Two linear strains along orthogonal axes and the shear strain between those axes is determined by a variation of Yamaguchi's laser-speckle strain gage technique. It offers the advantages of shorter data acquisition times, less stringent alignment requirements, and reduced decorrelation effects when compared to a previously implemented optical strain rosette technique. The method automatically cancels the translational and rotational components of rigid body motion while simplifying the optical system and improving the speed of response.

  14. Multiple Comparison Analysis of Two New Genomic Sequences of ILTV Strains from China with Other Strains from Different Geographic Regions

    Zhao, Yan; Kong, Congcong; Wang, Yunfeng

    2015-01-01

    To date, twenty complete genome sequences of ILTV strains have been published in GenBank, including one strain from China, and nineteen strains from Australian and the United States. To investigate the genomic information on ILTVs from different geographic regions, two additional individual complete genome sequences of WG and K317 strains from China were determined. The genomes of WG and K317 strains were 153,505 and 153,639 bp in length, respectively. Alignments performed on the amino acid s...

  15. Effects of strain and strain rate on electronic behavior of metal surfaces under bending and tension tests

    Surface electronic behavior of MEMS and NEMS can be characterized using the Kelvin probe technique by measurements of work function (WF). However, the physical mechanism responsible for such electronic behavior of a surface subjected to mechanical loading has not been completely understood. In this study, changes in WF of copper and aluminum with respect to strain and strain rate under bending and tension tests were measured using a scanning Kelvin probe. The results showed that plastic strain and strain rate can decrease WF although elastic strain may lead to complex changes in WF, which can be explained well using the electrostatic energy model on dislocation density.

  16. Strain-based fatigue data for Ti-6Al-4V ELI under fully-reversed and mean strain loads.

    Carrion, Patricio E; Shamsaei, Nima

    2016-06-01

    This article presents the experimental data supporting the study to obtain the mean strain/stress effects on the fatigue behavior of Ti-6Al-4V ELI. A series of strain-controlled fatigue experiments on Ti-6Al-4V ELI were performed at four strain ratios (-1, -0.5, 0, and 0.5). Two types of data are included for each specimen. These are the hysteresis stress-strain responses for the cycle in a log10 increment, and the maximum and minimum stress-strain responses for each cycle. Fatigue lives are also reported for all the experiments. PMID:26952022

  17. Valsalva maneuver: shortest optimal expiratory strain duration

    Ramesh K. Khurana, Md

    2011-07-01

    Full Text Available Purpose : To quantitate the level of difficulty and determine consistency of hemodynamic responses with various expiratory strain (ES durations. Methods : Thirty-four healthy subjects performed the Valsalva maneuver (VM with an ES duration of 10, 12, and 15 seconds in random order. Level of difficulty after each trial was rated 1 to 10, with 10 being the most difficult. Blood pressure and heart rate (HR were recorded continuously and non-invasively. Parameters studied were Valsalva ratio (VR, early phase II (IIE, late phase II (IIL, tachycardia latency (TL, bradycardia latency (BL, and overshoot latency (OV-L. Consistency of responses was calculated. Results : Difficulty increased significantly with increased ES duration: 5.1±0.1 (mean±SEM at 10 seconds, 5.9±0.1 at 12 seconds, and 6.8±0.1 at 15 seconds (p<0.001. Phase IIE, TL, BL, OV-L, and VR response did not differ statistically with increasing ES durations, and there were no differences in variability. Phase IIL response increased significantly with increasing ES duration. Phase IIL was poorly delineated in 14 of 102 trials with 10 seconds ES duration. Conclusions : ES duration of 10 seconds created a low level of difficulty in healthy individuals. This strain duration produced consistent hemodynamic response for all parameters tested except IIL phase. The absence of IIL phase with 10 seconds ES should not be interpreted as an indicator of sympathetic vasoconstrictor failure.

  18. Substrate-induced strain in carbon nanodisks

    Graphitic nanodisks of typically 20–50 nm in thickness, produced by the so-called Kvaerner Carbon Black and Hydrogen Process were dispersed on gold substrate and investigated by atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM), and confocal Raman spectroscopy. The roughness of the gold surface was drastically changed by annealing at 400 °C. AFM measurements show that this change in the surface roughness induces changes also in the topography of the nanodisks, as they closely follow the corrugation of the gold substrate. This leads to strained nanodisks, which is confirmed also by confocal Raman microscopy. We found that the FE-SEM contrast obtained from the disks depends on the working distance used during the image acquisition by In-lens detection, a phenomenon which we explain by the decrease in the amount of electrons reaching the detector due to diffraction. This process may affect the image contrast in the case of other layered materials, like hexagonal boron nitride, and other planar hybrid nanostructures, too. - Highlights: • Bending of carbon nanodisks is induced by the roughness of the gold substrate. • Confocal Raman microscopy shows a compressive strain induced in the nanodisks. • The electron microscopy contrast of nanodisks depends on the working distance

  19. Systems strategies for developing industrial microbial strains.

    Lee, Sang Yup; Kim, Hyun Uk

    2015-10-01

    Industrial strain development requires system-wide engineering and optimization of cellular metabolism while considering industrially relevant fermentation and recovery processes. It can be conceptualized as several strategies, which may be implemented in an iterative fashion and in different orders. The key challenges have been the time-, cost- and labor-intensive processes of strain development owing to the difficulties in understanding complex interactions among the metabolic, gene regulatory and signaling networks at the cell level, which are collectively represented as overall system performance under industrial fermentation conditions. These challenges can be overcome by taking systems approaches through the use of state-of-the-art tools of systems biology, synthetic biology and evolutionary engineering in the context of industrial bioprocess. Major systems metabolic engineering achievements in recent years include microbial production of amino acids (L-valine, L-threonine, L-lysine and L-arginine), bulk chemicals (1,4-butanediol, 1,4-diaminobutane, 1,5-diaminopentane, 1,3-propanediol, butanol, isobutanol and succinic acid) and drugs (artemisinin). PMID:26448090

  20. Strain-Induced Ferroelectric Topological Insulator.

    Liu, Shi; Kim, Youngkuk; Tan, Liang Z; Rappe, Andrew M

    2016-03-01

    Ferroelectricity and band topology are two extensively studied yet distinct properties of insulators. Nonetheless, their coexistence has never been observed in a single material. Using first-principles calculations, we demonstrate that a noncentrosymmetric perovskite structure of CsPbI3 allows for the simultaneous presence of ferroelectric and topological orders with appropriate strain engineering. Metallic topological surface states create an intrinsic short-circuit condition, helping stabilize bulk polarization. Exploring diverse structural phases of CsPbI3 under pressure, we identify that the key structural feature for achieving a ferroelectric topological insulator is to suppress PbI6 cage rotation in the perovskite structure, which could be obtained via strain engineering. Ferroelectric control over the density of topological surface states provides a new paradigm for device engineering, such as perfect-focusing Veselago lens and spin-selective electron collimator. Our results suggest that CsPbI3 is a simple model system for ferroelectric topological insulators, enabling future studies exploring the interplay between conventional symmetry-breaking and topological orders and their novel applications in electronics and spintronics. PMID:26814668

  1. Physics of strained quantum well lasers

    Loehr, John P

    1998-01-01

    When this publisher offered me the opportunity to \\\\Tite a book, some six years ago, I did not hesitate to say yes. I had just spent the last four years of graduate school struggling to understand the physics of strained quantum well lasers, and it seemed to me the whole experience was much more difficult that it should have been. For although many of the results I needed were easy to locate, the underlying physical premises and intervening steps were not. If only I had a book providing the derivations, I could have absorbed them and gone on my way. Such a book lies before you. It provides a unified and self-contained descrip­ tion of the essential physics of strained quantum well lasers, starting from first principles whenever feasible. The presentation I have chosen requires only the standard introductory background in quantum mechanics, solid state physics, and electromagnetics expected of entering graduate students in physics or elec­ trical engineering. A single undergraduate course in each of these su...

  2. Physiological strain and countermeasures with firefighting.

    Cheung, S S; Petersen, S R; McLellan, T M

    2010-10-01

    Protective clothing is integral to the task of firefighting, but at the same time can increase physiological strain and impair work capacity. Encapsulation of the head and the high thermal resistance and/or low water vapor permeability of the clothing ensemble impede evaporative heat dissipation, thus elevating the rate of heat storage and creating a state of uncompensable heat stress (UHS). In addition, the additional weight from carrying a supplemental air supply and the greater respiratory work of breathing through a regulator can create a negative spiral of thermal hyperpnea from greater respiratory demands and metabolic heat production. The elevated respiratory demands also increase cardiac strain and potentially the risk for myocardial events. Tolerance time during UHS is determined by three factors: the core temperature at the beginning of the heat stress exposure, the core temperature that can be tolerated before exhaustion or collapse ensues, and the rate of increase in core temperature from the beginning to end of the heat stress exposure. Protective clothing is often employed in highly dynamic environments, making portability, longevity and integration with the task requirements and clothing critical design characteristics for countermeasures. To date, most countermeasures have been relatively indirect in nature, primarily with alterations in work scheduling along with physiological manipulations such as cooling manipulations during recovery periods. Advances are required in materials science to develop lighter and less restrictive protective equipment, concurrent with cooling strategies that target specific regions or which can be effectively implemented during exercise. PMID:21029197

  3. Subsurface micro-lattice strain mapping

    Ananthanarayanan, T. S.; Rosemeier, R. G.; Mayo, W. E.; Becla, P.

    Defect morphology and distribution up to depths of 20 microns have been shown to be critical to device performance in microelectronic applications. A unique and novel X-ray diffraction method called DARC (digital automated rocking curve) topography has been effectively utilized to map crystalline microlattice strains in various substrates and epitaxial films. The spatial resolution of this technique is in the the order of 100 microns and the analysis time for a 2 sq cm area is about 10 secs. DARC topography incorporates state-of-the-art one-dimensional and two-dimensional X-ray detectors to modify a conventional double crystal diffractometer to obtain color X-ray rocking curve topographs. This technique, being nondestructive and nonintrusive in nature, is an invaluable tool in materials' quality control for IR detector fabrication. The DARC topographs clearly delineate areas of micro-plastic strain inhomogeniety. Materials analyzed using this technique include HgMnTe, HgCdTe, BaF2, PbSe, PbS both substrates and epitaxial films.

  4. A magnetically actuated cellular strain assessment tool for quantitative analysis of strain induced cellular reorientation and actin alignment

    Khademolhosseini, F.; Liu, C.-C.; Lim, C. J.; Chiao, M.

    2016-08-01

    Commercially available cell strain tools, such as pneumatically actuated elastomer substrates, require special culture plates, pumps, and incubator setups. In this work, we present a magnetically actuated cellular strain assessment tool (MACSAT) that can be implemented using off-the-shelf components and conventional incubators. We determine the strain field on the MACSAT elastomer substrate using numerical models and experimental measurements and show that a specific region of the elastomer substrate undergoes a quasi-uniaxial 2D stretch, and that cells confined to this region of the MACSAT elastomer substrate undergo tensile, compressive, or zero axial strain depending on their angle of orientation. Using the MACSAT to apply cyclic strain on endothelial cells, we demonstrate that actin filaments within the cells reorient away from the stretching direction, towards the directions of minimum axial strain. We show that the final actin orientation angles in strained cells are spread over a region of compressive axial strain, confirming previous findings on the existence of a varied pre-tension in the actin filaments of the cytoskeleton. We also demonstrate that strained cells exhibit distinctly different values of actin alignment coherency compared to unstrained cells and therefore propose that this parameter, i.e., the coherency of actin alignment, can be used as a new readout to determine the occurrence/extent of actin alignment in cell strain experiments. The tools and methods demonstrated in this study are simple and accessible and can be easily replicated by other researchers to study the strain response of other adherent cells.

  5. Silicon strain gages bonded on stainless steel using glass frit for strain sensor applications

    In this paper, a steel pressure sensor using strain gages bonded on a 17–4 PH stainless steel (SS) diaphragm based on glass frit technology is proposed. The strain gages with uniform resistance are obtained by growing an epi-silicon layer on a single crystal silicon wafer using epitaxial deposition technique. The inorganic glass frits are used as the bonding material between the strain gages and the 17–4 PH SS diaphragm. Our results show that the output performances of sensors at a high temperature of 125 °C are almost equal those at room temperature, which indicates that the glass frit bonding is a good method and may lead to a significant advance in the high temperature applicability of silicon strain gage sensors. Finally, the microstructure of the cured organic adhesive and the fired glass frit are compared. It may be concluded that the defects of the cured organic adhesive deteriorate the hysteresis and repeatability errors of the sensors. (paper)

  6. Strain bidimensional na cardiopatia de Takotsubo Two-dimensional strain in Takotsubo cardiomyopathy

    Carlos Bellini G. Gomes

    2010-08-01

    Full Text Available Este relato apresenta o seguimento tardio de um caso de cardiomiopatia de Takotsubo com boa evolução clínica e melhora da função sistólica global ventricular esquerda. Contudo, observou-se persistência de significativa disfunção sistólica regional longitudinal que foi avaliada por meio de nova técnica ecocardiográfica (speckle tracking, com as medidas do strain (S e strain rate (SR correspondentes. Ressaltamos a importância desse novo método para o acompanhamento dessa cardiopatia, pois permite identificar os pacientes que persistem com disfunção sistólica e que possivelmente serão beneficiados com a manutenção da terapêutica clínica.This report presents the late follow-up of a case of Takotsubo cardiomyopathy with good clinical outcome and improved left ventricular global systolic function. However, there was persistence of significant regional longitudinal systolic dysfunction evaluated using a new echocardiographic technique (speckle tracking, with corresponding measures of strain (S and strain rate (SR. We emphasize the importance of this new method to monitoring this cardiomyopathy, since it identifies patients with persistent systolic dysfunction who will possibly benefit from maintenance of clinical therapy

  7. Genome Sequence of Campylobacter jejuni strain 327, a strain isolated from a turkey slaughterhouse

    Takamiya, Monica; Özen, Asli Ismihan; Rasmussen, Morten;

    2011-01-01

    , catalase positive bacterium obtains energy from the metabolism of amino acids and Krebs cycle intermediates. Strain 327 was isolated from a turkey slaughter production line and is considered environmentally sensitive to food processing (cold, heat, drying) and storage conditions. The 327 whole genome...

  8. Silicon strain gages bonded on stainless steel using glass frit for strain sensor applications

    Zhang, Zongyang; Cheng, Xingguo; Leng, Yi; Cao, Gang; Liu, Sheng

    2014-05-01

    In this paper, a steel pressure sensor using strain gages bonded on a 17-4 PH stainless steel (SS) diaphragm based on glass frit technology is proposed. The strain gages with uniform resistance are obtained by growing an epi-silicon layer on a single crystal silicon wafer using epitaxial deposition technique. The inorganic glass frits are used as the bonding material between the strain gages and the 17-4 PH SS diaphragm. Our results show that the output performances of sensors at a high temperature of 125 °C are almost equal those at room temperature, which indicates that the glass frit bonding is a good method and may lead to a significant advance in the high temperature applicability of silicon strain gage sensors. Finally, the microstructure of the cured organic adhesive and the fired glass frit are compared. It may be concluded that the defects of the cured organic adhesive deteriorate the hysteresis and repeatability errors of the sensors.

  9. Screening Three Strains of Pseudomonas aeruginosa: Prediction of Biosurfactant-Producer Strain

    Gholamreza Dehghan-Noudeh

    2009-01-01

    Full Text Available Problem statement: The chemical surfactants have some disadvantages; especially, toxicity and no biodegradability. Approach: Biosurfactants were the structurally diverse group of surface-active molecules synthesize by micro-organisms. The microbial surfactants were interesting, because of the biodegradable and have many applications in industry, agriculture, medicine. Results: In the present study, the production of biosurfactant by three strains of Pseudomonas aeruginosa (PTCC 1074, 1310 and 1430 was investigated. The hemolytic and foam forming activity of different strains were studied and consequently, P. aeruginosa PTCC 1074 was selected as the suitable strain. P. aeruginosa PTCC 1074 was grown in the nutrient broth medium and biosurfactant production was evaluated every 24 h by emulsification index and surface tension for the best of production time. After that, in order to get maximum production of biosurfactant, the selected strain was grown with different additives in nutrient broth and the best culture medium was found. The biosurfactant was isolated from the supernatant and its amphipathic structure was confirmed by chemical methods. Conclusion: Biosurfactant produced by Pseudomonas aeruginosa PTCC 1074 would be considered as a suitable surfactant in industries due to its low toxicity.

  10. Metabolomic study of Chilean biomining bacteria Acidithiobacillus ferrooxidans strain Wenelen and Acidithiobacillus thiooxidans strain Licanantay.

    Martínez, Patricio; Gálvez, Sebastián; Ohtsuka, Norimasa; Budinich, Marko; Cortés, María Paz; Serpell, Cristián; Nakahigashi, Kenji; Hirayama, Akiyoshi; Tomita, Masaru; Soga, Tomoyoshi; Martínez, Servet; Maass, Alejandro; Parada, Pilar

    2013-02-01

    In this study, we present the first metabolic profiles for two bioleaching bacteria using capillary electrophoresis coupled with mass spectrometry. The bacteria, Acidithiobacillus ferrooxidans strain Wenelen (DSM 16786) and Acidithiobacillus thiooxidans strain Licanantay (DSM 17318), were sampled at different growth phases and on different substrates: the former was grown with iron and sulfur, and the latter with sulfur and chalcopyrite. Metabolic profiles were scored from planktonic and sessile states. Spermidine was detected in intra- and extracellular samples for both strains, suggesting it has an important role in biofilm formation in the presence of solid substrate. The canonical pathway for spermidine synthesis seems absent as its upstream precursor, putrescine, was not present in samples. Glutathione, a catalytic activator of elemental sulfur, was identified as one of the most abundant metabolites in the intracellular space in A. thiooxidans strain Licanantay, confirming its participation in the sulfur oxidation pathway. Amino acid profiles varied according to the growth conditions and bioleaching species. Glutamic and aspartic acid were highly abundant in intra- and extracellular extracts. Both are constituents of the extracellular matrix, and have a probable role in cell detoxification. This novel metabolomic information validates previous knowledge from in silico metabolic reconstructions based on genomic sequences, and reveals important biomining functions such as biofilm formation, energy management and stress responses. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s11306-012-0443-3) contains supplementary material, which is available to authorized users. PMID:23335869

  11. Strain rate dependency of oceanic intraplate earthquake b-values at extremely low strain rates

    Sasajima, Ryohei; Ito, Takeo

    2016-06-01

    We discovered a clear positive dependence of oceanic intraplate earthquake (OCEQ) b-values on the age of the oceanic lithosphere. OCEQ b-values in the youngest (20 Ma) oceanic lithosphere exceed 1.5, which is significantly higher than the average worldwide earthquake b-value (around 1.0). On the other hand, the b-value of intraplate earthquakes in the Ninety East-Sumatra orogen, where oceanic lithosphere has an anomalously higher strain rate compared with normal oceanic lithosphere, is 0.93, which is significantly lower than the OCEQ b-value (about 1.9) with the same age (50-110 Ma). Thus, the variation in b-values relates to the strain rate of the oceanic lithosphere and is not caused by a difference in thermal structure. We revealed a negative strain rate dependency of the b-value at extremely low strain rates (1.5) in oceanic lithosphere >20 Ma old imply that future improvement in seismic observation will capture many smaller magnitude OCEQs, which will provide valuable information on the evolution of the oceanic lithosphere and the driving mechanism of plate tectonics.

  12. Application of fiber optic grating strain sensor for measurement of strain under irradiation environment

    Kaji, Y.; Matsui, Y.; Kita, S.; Ide, H.; Tsukada, T.; Tsuji, H. [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan)

    2001-07-01

    In Japan Atomic Energy Research Institute (JAERI), in-pile strain measurement techniques have been developed using Japan Materials Testing Reactor (JMTR). In order to evaluate the performance of fiber optic grating sensor under irradiation environment, heat-up and performance tests at elevated temperature before irradiation and in-pile tests were performed in JMTR. (author)

  13. Impact of strain engineering on nanoscale strained InGaAs MOSFET devices.

    Lee, Chang-Chun; Chang, Shu-Tong; Sun, P-H; Huang, C-X

    2011-07-01

    The strain distributions in the In(0.53)Ga(0.47)As channel regions of the In(0.4)Ga(0.6)As source/drain (S/D) with various lengths and widths were studied via 3D process simulations. The resulting mobility improvement was analyzed. The tensile strain along the transport direction was found to dominate the mobility improvement. The strain along the vertical direction perpendicular to the gate oxide was found to affect the mobility the least, while the strain along the width direction was slightly degraded. The impact of the channel width and length on the performance improvement, such as on the mobility gain, was analyzed via TCAD simulations. The novelty of this paper stems from its study of the impact of the channel width and length on the performance of InGaAs NMOSFETs, such as on their mobility gain, and from its exploration of physical insights for scaling the future III-V MOS devices. PMID:22121581

  14. Serial subcultivation of Czechoslovakian and Japanese BCG strains.

    Osborn, T W

    1980-10-01

    Changes in the Danish BCG strain under certain regimens of subculture have been shown in preceding studies to be associated with selection of a minority population. Three Czechoslovakian BCG strains, all originally derived from the Danish strain but thereafter and in distinction from it maintained on potato media, have now been investigated. Changes in the immunizing potency of two of these strains have been attributed by other workers to employment of the richer potato media in place of Sauton medium as used for maintenance of the parent Danish strain. However, results from the present study suggest rather that selection of a pre-existing minority genotype or of a new mutant occurred. This proposal is supported by the finding that the third strain has maintained characteristics similar to those of the Danish parent despite many previous transfers on potato media.Another BCG strain investigated was the Japanese which, like the three Czechoslovakian strains, had been previously maintained on potato media. This strain has been shown in the present study to resemble the Danish strain in supporting a minority population yielding non-spreading colonies. Czechoslovakian vaccine prepared with seed culture supplied from Tokyo has retained characteristics similar to those of the Japanese parent. Although a majority population yielding spreading colonies appears so far to have been retained in both centres, it is considered that selection of the minority could still occur in the course of routine transfer. PMID:7005326

  15. Identification of Iron-reducing Thermus strains as Thermus scotoductus

    Balkwill, David L.; Kieft, T L.; Tsukuda, Toyoko; Kostandarithes, Heather M.; Onstott, T C.; Macnaughton, S.; Bownas, J.; Fredrickson, Jim K.

    2004-02-01

    Thermus strain SA-01, previously isolated from a deep (3.2) South African gold mine, is closely related to Thermus strains NMX2 A.1 and VI-7 (previously isolated from thermal springs in New Mexico USA and Portugal, respectively). Thermus strains SA-01 and NMX2 A.1 have also been shown previously to grow using nitrate, Fe(III), , Mn(IV) or So as terminal electron acceptors and to be capable of reducing Cr(VI), U(VI), Co(III), and the quinine-containing compound anthraquinone-2,6-disulfonate. The objectives of this study were to determine the phylogenetic positions of the three known metal-reducing Thermus strains and to determine the phylogenetic significance of metal reduction within the genus Thermus. Phylogenetic analyses of 16S rDNA sequences, BOX PCR genomic fingerprinting, and DNA-DNA reassociation analyses indicated that these strains belong to the previously described genospecies T. scotoductus. The morphologies and lipid fatty acid profiles of these metal-reducing strains are consistent with their identification as T. scotoductus; however, the T. scotoductus strains tested in this study evinced a wide intraspecies variability in some other phenotypic traits, e.g., carbon substrate utilization and pigmentation. Iron reduction occurred in all strains of T. scotoductus tested except the mixotrophic, sulfur-oxidizing strain IT-7254. Thermus strains belonging to other species did not reduce Fe(III) to Fe(II) or reduced it only poorly.

  16. Nutritional values of different strains of mushrooms (Agaricus bisporus

    Józef Bąkowski

    2013-12-01

    Full Text Available The nutritional values and chemical composition of different strains of the mushroom (Agaricus bisporus were studied. The study covered four strains cultivated in Poland: OCNOS-1, Somycel-11 , Somycel-92, and Somycel-653. The samples were analyzed for dry matter, vitamin C, nitrates, nitrites, total nitrogen and crude protein (N × 4.38, amino acid composition, soluble carbohydrates composition, and minerals content. Besides, whiteness values were determined by Hunter's method. All determinations were made on two of fruit-bodies of two sizes: 25-40 mm in pileus diameter (small and 40-50 mm in pileus diameter (large. A significantly higher dry matter content was found in strain 1 in comparison with strain 92. The lowest value of total nitrogen was detected for strain 92 and the highest for strain 653. From among the four analyzed strains, strain 92 contained the highest amount of essential amino acids. Trehalose content was significantly lower in strain 11 in comparison with other strains both in small and large fruit-body.

  17. Relatedness of Thermomyces lanuginosus strains producing a thermostable xylanase.

    Singh, S; Reddy, P; Haarhoff, J; Biely, P; Janse, B; Pillay, B; Pillay, D; Prior, B A

    2000-08-25

    Properties of an endo-beta-xylanase produced by a locally isolated Thermomyces lanuginosus strain SSBP was compared to seven other T. lanuginosus strains isolated from different geographical regions. Strain SSBP produced the highest xylanase activity of 59600 nkat ml(-1) when cultivated on corn cobs (maize) medium, whereas the seven other strains produced xylanase activities ranging from 6000 to 32000 nkat ml(-1). No cellulase activity was produced by the strains. Despite the variability in the production of xylanase, little difference in the other characteristics of the strains could be found. The optimal temperature and pH for xylanase production by the strains was either 40 or 50 degrees C and between pH 6 and 7, respectively. Optimal xylanase activity of the strains was observed at 70 degrees C and at pH 6 or 6.5. Culture supernatant analysis by SDS-PAGE and isoelectric focusing PAGE of all strains revealed the presence of a single 24.7 kDa and pI 3.9 xylanase. Phylogenetic analysis by PCR amplification and sequencing of the internal transcribed spacer of nuclear rRNA repeat units and 5.8S rDNA revealed no strain diversity. However, random amplified polymorphic DNA analysis pointed to greater diversity and with one primer (5'-GCCCGACGCG-3'), a relationship was established between xylanase levels and the RAPD pattern. PMID:10989171

  18. Antimicrobial drug susceptibility of Neisseria meningitidis strains isolated from carriers

    Dayamí García

    2000-06-01

    Full Text Available When it is necessary to determine the susceptibility of Neisseria meningitidis (Nm strains to antimicrobial drugs, it is important to consider that it should be analyzed in a double context. One of them related to the use of drugs in a specific medical treatment; and the other; to chemoprophylatic drugs, both with the same purpose: the accurate selection of the “in vivo” antimicrobial agent. This requires the study of the sensitivity and resistance of strains isolated in both carriers and patients. With the aim of further studying the behavior of the strains that currently circulate in Cuba, an antimicrobial drug susceptibility study was conducted in 90 strains isolated from carriers during the first half of 1998. The agar dilution method was used to determine the minimum inhibitory concentrations (MICs to: penicillin, ampicillin, rifampin, sulfadiazine, chloramphenicol, ciprofloxacin, ceftriaxone, cefotaxime. The study of the three latter drugs was done for the first time in our country. The search for β- lactamase-producer strains was also performed. There was a predominance of penicillin sensitive strains (82,2% with an intermediate sensitivity to ampicillin (57,8%, while 70% of the strains were sensitive to sulfadiazine. Regarding the rest of the antimicrobial drugs, 100% of the strains were sensitive. The paper shows the MICs for each drug as well as the phenotypic characteristics of the strains with the penicillin and sulfadiazine sensitivity and resistance patterns. No β-lactamase-producer strains were found.

  19. The complete genome of Enterovirus 71 China strain

    2001-01-01

    Five overlapping clones covering the full genome of Enterovirus71 China strain SHZH98 were obtained and then the sequences were determined by the chain termination method. It showed that the full length of EV71 SHZH98 genome (not including Poly A tail) is 7408 bp. There are some diversities on the lengths and sequences of 5′ UTR and 3′ UTR between SHZH98 and the other EV71 strains. In P1 capsid region, which is closely associated with viral immunogenicity, EV71 strain SHZH98 shares the highest homology with Taiwan strains; but in P2 and P3 non-structural gene regions there are higher identities with Coxsakievirus A16 and EV71 strains MS, BrCr than with Taiwan strains. Phylogenetic tree constructed by structural gene region indicates that China strain SHZH98 has a closer relationship with Taiwan strains, however, in the non-coding region it has a closer relationship with Coxsakievirus A16, EV71 strains MS and BrCr. EV71 China strain was analyzed at the molecular level. The results will contribute to the basic study on enteroviruses and the EV71 prevention in China.

  20. Information interoperability and information standardisation for NATO C2 - a practical approach

    Lasschuyt, E.; Hekken, M.C. van

    2001-01-01

    Interoperability between information systems is usually 'achieved' by enabling connection at network level. Making systems really interoperable, by letting them understand and manipulate the exchanged information, requires a lot more. Above all, information standards are needed in order to gain common understanding about what will be exchanged. Besides that, information standardisation should be considered from a global point of view, taking into account the whole range of systems that will p...

  1. LT^2C^2: A language of thought with Turing-computable Kolmogorov complexity

    Santiago Figueira

    2013-03-01

    Full Text Available In this paper, we present a theoretical effort to connect the theory of program size to psychology by implementing a concrete language of thought with Turing-computable Kolmogorov complexity (LT^2C^2 satisfying the following requirements: 1 to be simple enough so that the complexity of any given finite binary sequence can be computed, 2 to be based on tangible operations of human reasoning (printing, repeating,. . . , 3 to be sufficiently powerful to generate all possible sequences but not too powerful as to identify regularities which would be invisible to humans. We first formalize LT^2C^2, giving its syntax and semantics, and defining an adequate notion of program size. Our setting leads to a Kolmogorov complexity function relative to LT^2C^2 which is computable in polynomial time, and it also induces a prediction algorithm in the spirit of Solomonoff’s inductive inference theory. We then prove the efficacy of this language by investigating regularities in strings produced by participants attempting to generate random strings. Participants had a profound understanding of randomness and hence avoided typical misconceptions such as exaggerating the number of alternations. We reasoned that remaining regularities would express the algorithmic nature of human thoughts, revealed in the form of specific patterns. Kolmogorov complexity relative to LT^2C^2 passed three expected tests examined here: 1 human sequences were less complex than control PRNG sequences, 2 human sequences were not stationary showing decreasing values of complexity resulting from fatigue 3 each individual showed traces of algorithmic stability since fitting of partial data was more effective to predict subsequent data than average fits. This work extends on previous efforts to combine notions of Kolmogorov complexity theory and algorithmic information theory to psychology, by explicitly proposing a language which may describe the patterns of human thoughts.Received: 12 December 2012, Accepted: 3 February 2013; Edited by: G. Mindlin; DOI: http://dx.doi.org/10.4279/PIP.050001Cite as: S Romano, M Sigman, S Figueira, Papers in Physics 5, 050001 (2013

  2. C2A2 Project - CO2 Capture by Advances Amines process

    This publication presents the operation principles and the obtained results for a research demonstrator developed in Le Havre by EDF and Alstom for CO2 capture by post-combustion. The implemented technology, developed by Alstom and DOX Chemical is named Advanced Amines Processes (AAP). This process comprises the use of solvent and a specific process scheme (the Advanced Flow Scheme or AFS). The smoke treatment chain of the installation is described, and the valorisation of combustion by-products and of smoke processing operations is indicated. The capacities of the installation are given. Systems aimed at increasing the solvent lifetime are described, and some operational parameters are indicated. Various aspects related to the demonstrator design, construction and operation are discussed. Results obtained during tests between October 2013 and March 2014 are given and discussed in terms of quantity of captured CO2, of energy performance, of solvent management and consumption, of emissions, of corrosion, of exploitation organisation, and of instrumentation verification and data quality

  3. Mo2TiAlC2: A new ordered layered ternary carbide

    Herein we report on the synthesis of a new layered ternary carbide, Mo2TiAlC2, that was synthesized by heating an elemental mixture at 1600 °C for 4 h under an Ar flow. Its hexagonal, a and c lattice parameters were calculated via Rietveld analysis of powder X-ray diffraction patterns to be, respectively, 2.997 Å and 18.661 Å. High-resolution scanning transmission electron microscopy showed that this phase is ordered, with Ti layers sandwiched between two Mo layers in a M3AX2 type ternary carbide structure

  4. TiC2 : A New Two-Dimensional Sheet beyond MXenes

    Zhao, Tianshan; Zhang, Shunhong; Guo, Yaguang; Wang, Qian

    MXenes are attracting attention due to their rich chemistry and intriguing properties. Here a new type of metal-carbon-based sheet composed of transition metal centers and C2 dimers rather than individual C atoms is designed. Taking the Ti system as a test case, density functional theory calculations combined with a thermodynamic analysis uncover the thermal and dynamic stability of the sheet, as well as a metallic band structure, anisotropic Young's modulus and Poisson's ratio, a high heat capacity, and a large Debye stiffness. Moreover, the TiC2 sheet has excellent Li storage capacity with a small migration barrier, a lower mass density compared with standard MXenes, and better chemical stability as compared to the MXene Ti2C sheet. When Ti is replaced with other transition metal centers, diverse new MC2 sheets containing C =C dimers can be formed, the properties of which merit further investigation.

  5. Stress and strain evolution of folding rocks

    Llorens, Maria-Gema; Griera, Albert; Bons, Paul; Gomez-Rivas, Enrique; Weikusat, Ilka

    2015-04-01

    One of the main objectives of structural geology is to unravel rock deformation histories. Fold shapes can be used to estimate the orientation and amount of strain associated with folding. However, much more information on rheology and kinematics can potentially be extracted from fold geometries (Llorens et al., 2013a). We can study the development of folds, quantify the relationships between the different parameters that determine their geometries and estimate their mechanical evolution. This approach allows us to better understand and predict not only rock but also ice deformation. One of the main parameters in fold development is the viscosity contrast between the folding layer and the matrix in which it is embedded (m), since it determines the initial fold wavelength and the amplification rate of the developing folds. Moreover, non-linear viscous rheology influences fold geometry too (Llorens et al., 2013b). We present a series of 2-dimensional simulations of folding of viscous single layers in pure and simple shear. We vary different parameters in order to compare and determine their influence on the resulting fold patterns and the associated mechanical response of the material. To perform these simulations we use the software platform ELLE (www.elle.ws) with the non-linear viscous finite element code BASIL. The results show that layers thicken at the beginning of deformation in all simulations, and visible folds start earlier or later depending on the viscosity contrast. When folds start to nucleate the layer maximum shear strain decreases, moving away from the theoretical trend for homogeneous strain (no folding). This allows the accurate determination of the onset of folding. Maximum deviatoric stresses are higher in power-law than in linear-viscosity materials, and it is initially double in pure shear than in simple shear conditions. Therefore, folding a competent layer requires less work in simple than in pure shear. The maximum deviatoric stress

  6. Antibiotic Resistance in Diarrheagenic Escherichia coli and Shigella Strains Isolated from Children in Hanoi, Vietnam

    Nguyen, Trung Vu; Le Van, Phung; Le, Chinh Huy; Weintraub, Andrej

    2005-01-01

    The MICs for 162 diarrheagenic Escherichia coli strains and 28 Shigella strains were determined on the basis of NCCLS guidelines. More than 75% of the strains were resistant to ampicillin, chloramphenicol (53.6% of Shigella strains), and trimethoprim-sulfamethoxazole. Multiresistance was detected in 89.5% of E. coli strains and 78.6% of Shigella strains.

  7. Nano-beam electron diffraction evaluation of strain behaviour in nano-scale patterned strained silicon-on-insulator

    A major challenge for the application of strain engineering to enhance the performance of electronic devices is the quantification of strain on the nanoscale. Besides other techniques (Raman spectroscopy, X-ray diffraction) electron beam techniques allow strain analyses with a spatial resolution of a few nanometers and a reasonable strain sensitivity of 1 x 10-3 (relative to the lattice constant of silicon). In the present work, we address practical issues in the application of nano-beam electron diffraction (NBED) to probe the strain in strained silicon layers and sub-100 nm structures. The investigated specimens were prepared on biaxially tensile strained silicon-on-insulator substrates with an initial strain of ε = 0.6% or 0.8%. Results of the NBED experiments were compared to data obtained by other strain measurement techniques; amongst them the strain mapping by peak-pairs analysis of high-angle annular dark field (HAADF) images was especially considered (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  8. Development of a PCR assay for the strain-specific identification of probiotic strain Lactobacillus paracasei IMPC2.1.

    Sisto, Angelo; De Bellis, Palmira; Visconti, Angelo; Morelli, Lorenzo; Lavermicocca, Paola

    2009-11-30

    Recent investigations clearly indicate that the probiotic bacterium Lactobacillus paracasei IMPC2.1 can be incorporated into vegetables to obtain innovative probiotic foods whose marketing has been authorized by the Italian Ministry of Health. In this study, strain IMPC2.1 was characterized at a molecular level in order to define its taxonomic position and to develop a PCR test for strain-specific identification. Molecular methods, such as 16S rRNA gene sequencing and multiplex PCR, have provided evidence that strain IMPC2.1 indeed belongs to the L. paracasei species. In addition, a cluster analysis of fluorescent amplified fragment length polymorphism (f-AFLP) data strongly indicated that strain IMPC2.1 and nine other L. paracasei strains (including strain ATCC 334) belong to the same species and are definitely differentiated from the type strain L. casei ATCC 393. The f-AFLP technique was also used to identify a strain-specific DNA fragment of L. paracasei IMPC2.1 - encoding an amino acid sequence similar to a glycosyltransferase of probiotic strain Lactobacillus rhamnosus HN001 - which enabled us to develop a rapid PCR test for strain-specific identification. The strain-specificity of the PCR test was assessed by comparison with a total of 73 bacterial strains mainly isolated from vegetable products that did not produce any amplified fragment. These strains belonged to the L. paracasei species, to 6 additional species of Lactobacillus and to Weissella cibaria, W. confusa, Lactococcus lactis, Leuconostoc mesenteroides and Pediococcus pentosaceus. A method similar to the one used in this study can be adopted to develop easy, rapid detection techniques for monitoring other bacteria in complex microbiota. PMID:19833402

  9. Antimicrobial susceptibility pattern of Helicobacter suis strains.

    Vermoote, Miet; Pasmans, Frank; Flahou, Bram; Van Deun, Kim; Ducatelle, Richard; Haesebrouck, Freddy

    2011-12-15

    Helicobacter suis is a very fastidious porcine gastric pathogen, which is also considered to be of zoonotic importance. In vitro antimicrobial susceptibility cannot be determined using standard assays, as this agent only grows in a biphasic medium with an acidic pH. Therefore, a combined agar and broth dilution method was used to analyse the activity of nine antimicrobial agents against nine H. suis isolates. After 48 h microaerobic incubation, minimal inhibitory concentrations (MICs) were determined by software-assisted calculation of bacterial growth. Only for enrofloxacin a bimodal distribution of MICs was demonstrated, indicating acquired resistance in one strain, which showed an AGT→AGG (Ser→Arg) substitution at codon 99 of gyrA. In conclusion, the assay developed here is suitable for determination of the antimicrobial susceptibility of H. suis isolates, although activity of acid sensitive antimicrobial agents may be higher than predicted from MIC endpoints. PMID:21733643

  10. Ultrafast strain engineering in complex oxide heterostructures

    Popovich, Paul; Caviglia, Andrea; Hu, Wanzheng; Bromberger, Hubertus; Singla, Rashmi; Mitrano, Matteo; Hoffmann, Matthias C.; Kaiser, Stefan; Foerst, Michael [Max-Planck Research Group for Structural Dynamics - Center for Free Electron Laser Science, University of Hamburg (Germany); Scherwitzl, Raoul; Zubko, Pavlo; Gariglio, Sergio; Triscone, Jean-Marc [Departement de Physique de la Matiere Condensee, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneve 4, Geneva (Switzerland); Cavalleri, Andrea [Max-Planck Research Group for Structural Dynamics - Center for Free Electron Laser Science, University of Hamburg (Germany); Department of Physics, Clarendon Laboratory, University of Oxford (United Kingdom)

    2012-07-01

    The mechanical coupling between the substrate and the thin film is expected to be effective on the ultrafast timescale, and could be exploited for the dynamic control of materials properties. Here, we demonstrate that a large-amplitude mid-infrared field, made resonant with a stretching mode of the substrate, can switch the electronic properties of a thin film across an interface. Exploiting dynamic strain propagation between different components of a heterostructure, insulating antiferromagnetic NdNiO{sub 3} is driven through a prompt, five-order-of-magnitude increase of the electrical conductivity, with resonant frequency and susceptibility that is controlled by choice of the substrate material. Vibrational phase control, extended here to a wide class of heterostructures and interfaces, may be conductive to new strategies for electronic phase control at THz repetition rates.

  11. De novo generation of prion strains.

    Colby, David W; Prusiner, Stanley B

    2011-11-01

    Prions are self-replicating proteins that can cause neurodegenerative disorders such as bovine spongiform encephalopathy (also known as mad cow disease). Aberrant conformations of prion proteins accumulate in the central nervous system, causing spongiform changes in the brain and eventually death. Since the inception of the prion hypothesis - which states that misfolded proteins are the infectious agents that cause these diseases - researchers have sought to generate infectious proteins from defined components in the laboratory with varying degrees of success. Here, we discuss several recent studies that have produced an array of novel prion strains in vitro that exhibit increasingly high titres of infectivity. These advances promise unprecedented insight into the structure of prions and the mechanisms by which they originate and propagate. PMID:21947062

  12. Soliton trap in strained graphene nanoribbons

    The wavefunction of a massless fermion consists of two chiralities, left handed and right handed, which are eigenstates of the chiral operator. The theory of weak interactions of elementary particle physics is not symmetric about the two chiralities, and such a symmetry-breaking theory is referred to as a chiral gauge theory. The chiral gauge theory can be applied to the massless Dirac particles of graphene. In this paper, we show within the framework of the chiral gauge theory for graphene that a topological soliton exists near the boundary of a graphene nanoribbon in the presence of a strain. This soliton is a zero-energy state connecting two chiralities and is an elementary excitation transporting a pseudo-spin. The soliton should be observable by means of a scanning tunneling microscopy experiment.

  13. Indices of Psychological Strain During Hypoxis Bedrest

    Stavrou, Nektarios A.; McDonnell, Adam C.; Eiken, Ola; Mekjavic, Igor B.

    2013-02-01

    Much attention has been devoted to the physiological changes that occur during bed rest. However, there has been a lack of focus on the psychological aspects per se. We investigated indices of psychological strain during three 10-d interventions, designed to assess the combined effects of inactivity/unloading and normobaric hypoxia on several physiological systems. Eleven male participants underwent three 10-d campaigns in a randomized manner: 1) normobaric hypoxic ambulatory confinement (HAMB), 2) normobaric hypoxic bed rest (HBR) and 3) normoxic bed rest (NBR). The most negative psychological profile appeared on BR10 of HBR and HAmb conditions (hypoxic conditions). Concomitantly a decrease in positive emotions was observed from BR-2 to BR10. Bed rest and exposure to hypoxic environments seems to exert a negative effect on person’s psychological mood.

  14. Strain gradient effects on cyclic plasticity

    Niordson, Christian Frithiof; Legarth, Brian Nyvang

    2010-01-01

    Size effects on the cyclic shear response are studied numerically using a recent higher order strain gradient visco-plasticity theory accounting for both dissipative and energetic gradient hardening. Numerical investigations of the response under cyclic pure shear and shear of a finite slab between...... rigid platens have been carried out, using the finite element method. It is shown for elastic–perfectly plastic solids how dissipative gradient effects lead to increased yield strength, whereas energetic gradient contributions lead to increased hardening as well as a Bauschinger effect. For linearly...... hardening materials it is quantified how dissipative and energetic gradient effects promote hardening above that of conventional predictions. Usually, increased hardening is attributed to energetic gradient effects, but here it is found that also dissipative gradient effects lead to additional hardening in...

  15. Social relations: network, support and relational strain

    Due, P; Holstein, B; Lund, Rikke;

    1999-01-01

    We introduce a conceptual framework with social relations as the main concept and the structure and the function of social relations as subconcepts. The structure of social relations covers aspects of formal relations and social network. The function of social relations covers social support...... postal questionnaires were answered by a random sample in each of the age groups. The results show marked age and gender differences in both the structure and the function of social relations. The social network, measured as weekly contacts, weakens with age and so does instrumental support. Emotional...... support is unrelated to this decline in contact frequency and appears to be at the same level for younger and older individuals. Relational strain, measured as conflicts, declines with age for all kinds of social relations. The weakening of the social network with age does not seem to affect the level of...

  16. A new method of fabricating strained Silicon materials

    YANG Zongren; LIANG Renrong; XU Jun

    2006-01-01

    Strain-relaxed SiGe virtual substrates are of great importance for fabricating strained Si materials.Instead of using graded buffer method to obtain fully relaxed SiGe film, in this study a new method to obtain relaxed SiGe film and strained Si film with much thinner SiGe film was proposed.Almost fully relaxed thin SiGe buffer layer was obtained by Si/SiGe/Si multi-structure oxidation and the SiO2 layer removing before SiGe regrowth.Raman spectroscopy analysis indicates that the regrown SiGe film has a strain relaxation ratio of about 93% while the Si cap layer has a strain of 0.63%.AFM shows good surface roughness.This new method is proved to be a useful approach to fabricate thin relaxed epilayers and strain Si films.

  17. Strain Engineering to Modify the Electrochemistry of Energy Storage Electrodes

    Muralidharan, Nitin; Carter, Rachel; Oakes, Landon; Cohn, Adam P.; Pint, Cary L.

    2016-01-01

    Strain engineering has been a critical aspect of device design in semiconductor manufacturing for the past decade, but remains relatively unexplored for other applications, such as energy storage. Using mechanical strain as an input parameter to modulate electrochemical potentials of metal oxides opens new opportunities intersecting fields of electrochemistry and mechanics. Here we demonstrate that less than 0.1% strain on a Ni-Ti-O based metal-oxide formed on superelastic shape memory NiTi alloys leads to anodic and cathodic peak potential shifts by up to ~30 mV in an electrochemical cell. Moreover, using the superelastic properties of NiTi to enable strain recovery also recovers the electrochemical potential of the metal oxide, providing mechanistic evidence of strain-modified electrochemistry. These results indicate that mechanical energy can be coupled with electrochemical systems to efficiently design and optimize a new class of strain-modulated energy storage materials. PMID:27283872

  18. Do foliation refraction patterns around buckle folds represent finite strain?

    Frehner, M.; Exner, U.

    2012-04-01

    Buckle folds in the field commonly feature a characteristic syn-deformational foliation, which is sub-parallel to the fold axial plane; hence it is called axial plane foliation. As the foliation is not perfectly parallel to the axial plane, it may exhibit either a divergent or convergent fan around the fold. Convergent fans most commonly occur in the stronger rocks (the folded layer) while divergent fans rather occur in the mechanically weaker rocks (the matrix). The foliation orientation is usually thought to reflect the long axes of the finite strain ellipses, a hypothesis that we investigate in our study. To study the strain distribution around folds, we use the finite-element method to simulate two-dimensional single-layer viscous buckling. The numerical simulations allow to calculate the strain evolution during the folding process and to visualize its distribution and orientation around the fold. We use different measures of strain: (1) the finite strain (recording the strain history from the beginning of the simulation until the end), (2) the infinitesimal strain (capturing only the very last moment of the simulation), (3) the incremental strain (recording the strain history from a certain shortening value during the simulation until the end), and (4) initially layer-orthogonal passive marker lines. The shortening value, from which the incremental strain is calculated, can be anything between the beginning and the end of the simulation. The first three strain measures are tensor fields that are used to calculate and visualize the orientation of the long axis of the strain ellipses around the fold. We find that all strain measures result in a divergent fan in the mechanically weak matrix at the outer arc of the fold and that this divergent fan has almost the same geometry for all strain measures. Also, for the case of the incremental strain, the divergent fan does hardly depend on the moment from which the incremental strain is calculated. This observation

  19. Environment Identification in Flight using Sparse Approximation of Wing Strain

    Manohar, Krithika; Kutz, J Nathan

    2016-01-01

    This paper addresses the problem of identifying different flow environments from sparse data collected by wing strain sensors. Insects regularly perform this feat using a sparse ensemble of noisy strain sensors on their wing. First, we obtain strain data from numerical simulation of a Manduca sexta hawkmoth wing undergoing different flow environments. Our data-driven method learns low-dimensional strain features originating from different aerodynamic environments using Proper Orthogonal Decomposition (POD) modes in the frequency domain, and leverages compressed sensing and sparse approximation to classify a set of strain frequency signatures using a dictionary of POD modes. This bio-inspired machine learning architecture for dictionary learning and sparse classification permits fewer costly physical strain sensors while being simultaneously robust to sensor noise. A sensor placement algorithm identifies the frequency samples that best separate the different aerodynamic environments in rank-reduced POD feature...

  20. Strain engineering of diamond silicon vacancy centers in MEMS cantilevers

    Meesala, Srujan; Sohn, Young-Ik; Atikian, Haig; Holzgrafe, Jeffrey; Zhang, Mian; Burek, Michael; Loncar, Marko

    2016-05-01

    The silicon vacancy (SiV) center in diamond has recently attracted attention as a solid state quantum emitter due to its attractive optical properties. We fabricate diamond MEMS cantilevers, and use electrostatic actuation to apply controlled strain fields to single SiV centers implanted in these devices. The strain response of the four electronic transitions of the SiV at 737 nm is measured via cryogenic (4 K) photoluminescence excitation. We demonstrate over 300 GHz of tuning for the mean transition frequency between the ground and excited states, and over 100 GHz of tuning for the orbital splittings within the ground and excited states. The interaction Hamiltonian for strain fields is inferred, and large strain susceptibilities of the order 1 PHz/strain are measured. We discuss prospects to utilize our device to reduce phonon-induced decoherence in SiV spin qubits, and to exploit the large strain susceptibilities for hybrid quantum systems based on nanomechanical resonators.

  1. Genomic and gene variation in Mycoplasma hominis strains

    Christiansen, Gunna; Andersen, H; Birkelund, Svend;

    1987-01-01

    DNAs from 14 strains of Mycoplasma hominis isolated from various habitats, including strain PG21, were analyzed for genomic heterogeneity. DNA-DNA filter hybridization values were from 51 to 91%. Restriction endonuclease digestion patterns, analyzed by agarose gel electrophoresis, revealed no...... identity or cluster formation between strains. Variation within M. hominis rRNA genes was analyzed by Southern hybridization of EcoRI-cleaved DNA hybridized with a cloned fragment of the rRNA gene from the mycoplasma strain PG50. Five of the M. hominis strains showed identical hybridization patterns. These...... hybridization patterns were compared with those of 12 other mycoplasma species, which showed a much more complex band pattern. Cloned nonribosomal RNA gene fragments of M. hominis PG21 DNA were analyzed, and the fragments were used to demonstrate heterogeneity among the strains. A monoclonal antibody against...

  2. Strain Engineering to Modify the Electrochemistry of Energy Storage Electrodes

    Muralidharan, Nitin; Carter, Rachel; Oakes, Landon; Cohn, Adam P.; Pint, Cary L.

    2016-06-01

    Strain engineering has been a critical aspect of device design in semiconductor manufacturing for the past decade, but remains relatively unexplored for other applications, such as energy storage. Using mechanical strain as an input parameter to modulate electrochemical potentials of metal oxides opens new opportunities intersecting fields of electrochemistry and mechanics. Here we demonstrate that less than 0.1% strain on a Ni-Ti-O based metal-oxide formed on superelastic shape memory NiTi alloys leads to anodic and cathodic peak potential shifts by up to ~30 mV in an electrochemical cell. Moreover, using the superelastic properties of NiTi to enable strain recovery also recovers the electrochemical potential of the metal oxide, providing mechanistic evidence of strain-modified electrochemistry. These results indicate that mechanical energy can be coupled with electrochemical systems to efficiently design and optimize a new class of strain-modulated energy storage materials.

  3. Design of Monolithic Integrator for Strain-to-Frequency Converter

    Tuan Mohd. Khairi Tuan Mat

    2012-01-01

    Full Text Available Strain-to-Frequency converter (SFC is a one of the analog conditioner tools that converts any strain signal to the frequency signal. The basic concept of SFC is by detecting any changing of strains, then converting the strain to the voltage signal and converting the voltage signal to the frequency signal. This tool consists of 3 main  components which are strain gauge, differential integrator and comparator. This paper presents the designing and analysis of monolithic integrator that to be used in the Strain-toFrequency converter. The primary goal is to design and simulate the performance of monolithic integrator for SFC using GATEWAY Silvaco Electronic Design Automation (S EDA tools and EXPERT software. The performances of SFC using the designed monolithic integrator are also investigated.

  4. Pile Model Tests Using Strain Gauge Technology

    Krasiński, Adam; Kusio, Tomasz

    2015-09-01

    Ordinary pile bearing capacity tests are usually carried out to determine the relationship between load and displacement of pile head. The measurement system required in such tests consists of force transducer and three or four displacement gauges. The whole system is installed at the pile head above the ground level. This approach, however, does not give us complete information about the pile-soil interaction. We can only determine the total bearing capacity of the pile, without the knowledge of its distribution into the shaft and base resistances. Much more information can be obtained by carrying out a test of instrumented pile equipped with a system for measuring the distribution of axial force along its core. In the case of pile model tests the use of such measurement is difficult due to small scale of the model. To find a suitable solution for axial force measurement, which could be applied to small scale model piles, we had to take into account the following requirements: - a linear and stable relationship between measured and physical values, - the force measurement accuracy of about 0.1 kN, - the range of measured forces up to 30 kN, - resistance of measuring gauges against aggressive counteraction of concrete mortar and against moisture, - insensitivity to pile bending, - economical factor. These requirements can be fulfilled by strain gauge sensors if an appropriate methodology is used for test preparation (Hoffmann [1]). In this paper, we focus on some aspects of the application of strain gauge sensors for model pile tests. The efficiency of the method is proved on the examples of static load tests carried out on SDP model piles acting as single piles and in a group.

  5. Strain driven fast osseointegration of implants

    Wiesmann Hans-Peter

    2005-09-01

    Full Text Available Abstract Background Although the bone's capability of dental implant osseointegration has clinically been utilised as early as in the Gallo-Roman population, the specific mechanisms for the emergence and maintenance of peri-implant bone under functional load have not been identified. Here we show that under immediate loading of specially designed dental implants with masticatory loads, osseointegration is rapidly achieved. Methods We examined the bone reaction around non- and immediately loaded dental implants inserted in the mandible of mature minipigs during the presently assumed time for osseointegration. We used threaded conical titanium implants containing a titanium2+ oxide surface, allowing direct bone contact after insertion. The external geometry was designed according to finite element analysis: the calculation showed that physiological amplitudes of strain (500–3,000 ustrain generated through mastication were homogenously distributed in peri-implant bone. The strain-energy density (SED rate under assessment of a 1 Hz loading cycle was 150 Jm-3 s-1, peak dislocations were lower then nm. Results Bone was in direct contact to the implant surface (bone/implant contact rate 90% from day one of implant insertion, as quantified by undecalcified histological sections. This effect was substantiated by ultrastructural analysis of intimate osteoblast attachment and mature collagen mineralisation at the titanium surface. We detected no loss in the intimate bone/implant bond during the experimental period of either control or experimental animals, indicating that immediate load had no adverse effect on bone structure in peri-implant bone. Conclusion In terms of clinical relevance, the load related bone reaction at the implant interface may in combination with substrate effects be responsible for an immediate osseointegration state.

  6. Genetic Variability among Strains of the Entomopathogenic Nematode Steinernema feltiae

    Gaugler, Randy; McGuire, Terry; Campbell, James

    1989-01-01

    A systematic program of genetic improvement was initiated by assessing the phenotypic variation of Steinernema feltiae strains for two traits assumed to limit efficacy: ultraviolet tolerance and host-finding ability. All of the strains assayed showed both low ultraviolet tolerance and poor host-finding ability, indicating that the likelihood of improving these traits through more extensive population sampling is remote. Limited genetic variation was detected among the strains for tolerance to...

  7. Evolution of bulk strain solitons in cylindrical inhomogeneous shells

    Shvartz, A., E-mail: andrew.shvartz@mail.ioffe.ru; Samsonov, A.; Dreiden, G.; Semenova, I. [Ioffe Institute, 26 Politekhnicheskaya, St Petersburg 194021 (Russian Federation)

    2015-10-28

    Bulk strain solitary waves in nonlinearly elastic thin-walled cylindrical shells with variable geometrical and physical parameters are studied, and equation for the longitudinal strain component with the variable coefficients is derived. A conservative finite difference scheme is proposed, and the results of numerical simulation of the strain soliton evolution in a shell with the abrupt variations of cross section and physical properties of the material are presented.

  8. Identification of Bacillus Strains for Biological Control of Catfish Pathogens

    Ran, Chao; Carrias, Abel; Williams, Malachi A.; Capps, Nancy; Dan, Bui C. T.; Newton, Joseph C.; Joseph W Kloepper; Ooi, Ei L.; Browdy, Craig L.; Terhune, Jeffery S.; Liles, Mark R.

    2012-01-01

    Bacillus strains isolated from soil or channel catfish intestine were screened for their antagonism against Edwardsiella ictaluri and Aeromonas hydrophila, the causative agents of enteric septicemia of catfish (ESC) and motile aeromonad septicaemia (MAS), respectively. Twenty one strains were selected and their antagonistic activity against other aquatic pathogens was also tested. Each of the top 21 strains expressed antagonistic activity against multiple aquatic bacterial pathogens including...

  9. Visualization of ion transport in Nafion using electrochemical strain microscopy

    Kim, Suran; No, Kwangsoo; Hong, Seungbum

    2015-12-24

    The electromechanical response of a Nafion membrane immersed in water was probed using electrochemical strain microscopy (ESM) to redistribute protons and measure the resulting local strain that is caused by the movement of protons. We also measured the relaxation of protons from the surface resulting from proton diffusion. Using this technique, we can visualize and analyze the local strain change resulting from the redistribution and relaxation of hydrated protons.

  10. Preliminary Screening of Azolla Strains for Tolerance to Ammonuim Ion

    KITOH, Shunji; SHIOMI, Nobuyuki

    1995-01-01

    Azolla plants (117 strains from 7 species) were screened for tolerance to ammonium ion on the basis of their growth on the medium with or without ammonium. A. nilotica was the most sensitive species of all, followed by A. rubra whereas A. pinnata var. pinnata was the most tolerant one. From A. mexicana, A. caroliniana, A. microphylla and A. pinnata var. pinnata, 12 tolerant strains were selected. There was no tolerant strain in A. filiculoides as far as tested.

  11. Quantifying residual strains in specimens prepared by additive layer manufacturing

    Okioga, A.N.; Greene, R.J.; Tomlinson, R.A.

    2014-01-01

    Residual stresses and strains are prevalent in many components, especially those that are made using additive layer manufacturing. The residual strains are superposed onto any applied load, which in experimental analysis may lead to inaccurate results. The manufacture of a component with known residual strains in all build orientations will enable it to be tested in its green state with results similar to an annealed counterpart. This study has been conducted to explore the relationship betwe...

  12. Production of Sulfur Flavors by Ten Strains of Geotrichum candidum

    Berger, Celine; Khan, Jeffrey A.; Molimard, Pascal; Martin, Nathalie; Spinnler, Henry E.

    1999-01-01

    Ten strains of Geotrichum candidum were studied on a liquid cheese model medium for the production of sulfur compounds which contribute to the aroma of cheeses. The volatile components produced by each cultured strain were extracted by dynamic headspace extractions, separated and quantified by gas chromatography (GC), and identified by GC-mass spectrometry. It was shown that four strains of this microorganism produced significant quantities of S-methyl thioacetate, S-methyl thiopropionate, S-...

  13. Tensile Properties of Fiber Materials under Different Strain Rates

    XIONG Jie; GU Bo-hong; WANG Shan-yuan

    2002-01-01

    The quasi-static and dynamic tensile tests of aranid and high strength PVA fiber bundles are carried out under a wider range of strain rate by use of MTS (Materials Testing System) and bar-bar tensile impact apparatus.The influences of strain rate on mechanical properties of aramid and high strength polyvinyl alcohol fibers ar estudied. Micro failure mechanisms of fibers at different strain rates are examined by means of SEM.

  14. Measuring autogenous strain of concrete with corrugated moulds

    Tian, Qian; Jensen, Ole Mejlhede

    A reliable technique to quantify autogenous strain is a prerequisite to numerical modeling in stress calculations for high performance concrete. The introducing of a special kind of corrugated tube mould helps to transforming volume strain measurement into liner strain measurement in horizontal...... direction for fluid concrete, which not only realizes the continuous monitoring of the autogenous shrinkage since casting, but also effectively eliminates the disturbance resulting from gravity, temperature variation and mould restraint on measuring results. Based on this measuring technique, this paper...

  15. "Behaviour changes in Permethrin-resistant strain of Anopheles Stephensi "

    Vatandoost H

    2000-09-01

    Full Text Available Behaviour studies indicated that the permethrin resistant strin of An. Stephensi was 3-fold resistant to knock-down compared with the susceptible strain. The resistant strain was however 3-fold less irritable to permethrin and less responsive than the susceptible strain to the movement of an aspirator. If reduced irritability and reduced responsiveness to catch are consequences of the changes in the nervous system, then such a form of resistance may be disadvantageous to mosquitoes in natural populations.

  16. An extensometer for axial strain measurement at high temperature

    Schmidt, J.; Motoie, K.; Sakane, M.

    1983-01-01

    Most existing strain measuring instruments, important for the investigation of the mechanical behavior of metals at high temperature, have temperature, strain range, and size limitations. In this short note the authors give the design and construction of an extensometer with sufficient dynamic range and good stability over long periods of time, for measuring the longitudinal strain of plane specimens from 0.001 to 0.1 at temperatures up to 800 C.

  17. Strain Ellipsoid Determination Based on a Cretaceous Crocodyliform Fossil.

    Leonardo Morato; Ismar de Souza Carvalho

    2007-01-01

    Strain determination is usually possible bythe analyses of linear or angular features present inrocks that attest their deformation. In the absenceof direct evidence, the distortion of fossil materialspreserved within the rock can be used to approximatethe strain states. A distorted crocodyliform fossil ofthe genus Baurusuchus Price, 1945, collected in theGeneral Salgado municipality (specimen MPMA 64-0002/04), São Paulo state, was used in an attempt todetermine the orientation of the strain ...

  18. Mixed multilayered vertical heterostructures utilizing strained monolayer WS2.

    Sheng, Y.; Xu, W.; Wang, X.; He, Z.; Rong, Y.; Warner, JH

    2016-01-01

    Creating alternating layers of 2D materials forms vertical heterostructures with diverse electronic and opto-electronic properties. Monolayer WS2 grown by chemical vapour deposition can have inherent strain due to interactions with the substrate. The strain modifies the band structure and properties of monolayer WS2 and can be exploited in a wide range of applications. We demonstrate a non-aqueous transfer method for creating vertical stacks of mixed 2D layers containing a strained monolayer ...

  19. Low-temperature strain gauges based on silicon whiskers

    Druzhinin A. A.; Maryamova I. I.; Kutrakov A. P.; Pavlovskyy I. V.

    2008-01-01

    To create low-temperature strain gauges based on p-type silicon whiskers tensoresistive characteristics of these crystals in 4,2—300 K temperature range were studied. On the basis of p-type Si whiskers with different resistivity the strain gauges for different materials operating at cryogenic temperatures with extremely high gauge factor at 4,2 K were developed, as well as strain gauges operating at liquid helium temperatures in high magnetic fields.

  20. Strain measurement at the knee ligament insertion sites

    Hinterwimmer, S; Baumgart, R.; Plitz, W.

    2003-01-01

    We describe the modification of an existing method of ligament strain measurement at the knee joint in detail. At ten fresh joint specimens we used that technique where strain gauges are attached to the ligamentous insertions and origins. We both improved the preparation of the attachment site and the application of the strain gauges. In a special apparatus the specimens were moved from 0degrees extension to 100degrees flexion while simulating muscle strength and axial force. Testing was perf...

  1. True Stress-True Strain Models for Structural Steel Elements

    Arasaratnam, P.; K. S. Sivakumaran; Tait, M J

    2011-01-01

    A standard uniaxial tensile test, which establishes the engineering stress-strain relationship, in general, provides the basic mechanical properties of steel required by a structural designer. Modern numerical analysis techniques used for analysis of large strain problems such as failure analysis of steel structures and elements metal forming, metal cutting, and so forth, will require implementation and use of true stress-true strain material characterization. This paper establishes a five st...

  2. Reactions of strained hydrocarbons with alkene and alkyne metathesis catalysts.

    Carnes, Matthew; Buccella, Daniela; Siegrist, Theo; Steigerwald, Michael L; Nuckolls, Colin

    2008-10-29

    Here we describe the metathesis reactions of a strained eight-membered ring that contains both alkene and alkyne functionality. We find that the alkyne metathesis catalyst produces polymer through a ring-opening alkyne metathesis reaction that is driven by the strain release from the monomer. The strained monomer provides unusual reactivity with ruthenium-based alkene metathesis catalysts. We isolate a discrete trimeric species a Dewar benzene derivative that is locked in this form through an unsaturated cyclophane strap. PMID:18826219

  3. Viable versus inactivated lactobacillus strain GG in acute rotavirus diarrhoea.

    Kaila, M; Isolauri, E; Saxelin, M.; Arvilommi, H; Vesikari, T

    1995-01-01

    The effect of viable or heat inactivated human Lactobacillus casei strain GG on rotavirus immune responses in patients with rotavirus diarrhoea was assessed. Rotavirus serum IgA enzyme immunoassay antibody responses were higher in infants treated with viable L casei strain GG than in those treated with inactivated L casei strain GG. There was a significant difference at convalescence with rotavirus specific IgA secreting cells found in 10/12 infants receiving viable but only 2/13 infants rece...

  4. Differences in taste in button mushroom strains (Agaricus bisporus)

    Baars, J.J.P.; Stijger, I.; M. Kersten; Sonnenberg, A.S.M.

    2014-01-01

    This report describes the results of a screening of genetically diverse strains of mushroom Agaricus bisporus for differences in taste. Eight different strains were grown on regular commercial compost and casing soil. Two of these strains were also grown on a casing with calcium chloride added to increase osmotic value. The intension was to increase the dry matter content of the mushrooms that might affect the “bite” sensation of mushrooms.

  5. Vectorial strain gauge method using single flexible orthogonal polydimethylsiloxane gratings

    Hao Guo; Jun Tang; Kun Qian; Dimitris Tsoukalas; Miaomiao Zhao; Jiangtao Yang; Binzhen Zhang; Xiujian Chou; Jun Liu; Chenyang Xue; Wendong Zhang

    2016-01-01

    A vectorial strain gauge method using a single sensing element is reported based on the double-sided polydimethylsiloxane (PDMS) Fraunhofer diffraction gratings structures. Using O2 plasma treatment steps, orthogonal wrinkled gratings were fabricated on both sides of a pre-strained PDMS film. Diffracted laser spots from this structure have been used to experimentally demonstrate, that any applied strain can be quantitatively characterized in both the x and y directions with an error of less t...

  6. Magneto-strain-driven quantum engine on a graphene flake

    Peña, Francisco J.; Muñoz, Enrique

    2015-01-01

    We propose a novel conceptual design for a graphene-based quantum engine, driven by a superposition of mechanical strain and an external magnetic field. Engineering of strain in a nanoscale graphene flake creates a gauge field with an associated uniform pseudo-magnetic field. The strain-induced pseudo-magnetic field can be combined with a real magnetic field, leading to the emergence of discrete relativistic Landau levels within the single-particle picture. The inter-level distance and hence ...

  7. Improvements In A Laser-Speckle Surface-Strain Gauge

    Lant, Christian T.

    1996-01-01

    Compact optical subsystem incorporates several improvements over optical subsystems of previous versions of laser-speckle surface-strain gauge: faster acquisition of data, faster response to transients, reduced size and weight, lower cost, and less complexity. Principle of operation described previously in "Laser System Measures Two-Dimensional Strain" (LEW-15046), and "Two-Dimensional Laser-Speckle Surface-Strain Gauge" (LEW-15337).

  8. Salmonella strain secreting active listeriolysin changes its intracellular localization.

    Gentschev, I; Sokolovic, Z; Mollenkopf, H.J.; Hess, J; Kaufmann, S.H.; Kuhn, M; Krohne, G F; Goebel, W

    1995-01-01

    We describe the construction of an attenuated Salmonella dublin aroA strain which secretes via the Escherichia coli hemolysin secretion machinery an active hybrid cytolysin consisting of listeriolysin from Listeria monocytogenes and the C-terminal secretion signal of E. coli hemolysin. This hemolytic S. dublin strain is partially released into the cytoplasm of the host cell following uptake by J774 macrophage cells, whereas the nonhemolytic control S. dublin aroA strain remains in the phagosome.

  9. Low-temperature strain gauges based on silicon whiskers

    Druzhinin A. A.

    2008-08-01

    Full Text Available To create low-temperature strain gauges based on p-type silicon whiskers tensoresistive characteristics of these crystals in 4,2—300 K temperature range were studied. On the basis of p-type Si whiskers with different resistivity the strain gauges for different materials operating at cryogenic temperatures with extremely high gauge factor at 4,2 K were developed, as well as strain gauges operating at liquid helium temperatures in high magnetic fields.

  10. Context and strain-dependent behavioral response to stress

    Baum Amber E; Ahmadiyeh Nasim; Andrus Brian M; Dennis Kristen; Nosek Katarzyna; Woods Leah; Redei Eva E

    2008-01-01

    Abstract Background This study posed the question whether strain differences in stress-reactivity lead to differential behavioral responses in two different tests of anxiety. Strain differences in anxiety-measures are known, but strain differences in the behavioral responses to acute prior stress are not well characterized. Methods We studied male Fisher 344 (F344) and Wistar Kyoto (WKY) rats basally and immediately after one hour restraint stress. To distinguish between the effects of novelt...

  11. CHARACTERISTICS OF SHAPE MEMORY ALLOY AT HIGH STRAIN RATE

    Ogawa, K.

    1988-01-01

    In prospect of its wide technological applications, the dynamic response of shape memory alloy was investigated in the wide temperature range from 201K to 363K. The temperature and the strain rate effects on the stress-strain relations were clarified in connection with phase transformation. At high strain rates, characteristics of mechanical behaviours were well rationalized in terms of temperature change due to the endo- and exo-thermic process inevitably involved during deformation.

  12. Superconducting proximity effect in graphene under inhomogeneous strain

    Covaci, Lucian; Peeters, Francois

    2011-01-01

    The interplay between quantum Hall states and Cooper pairs is usually hindered by the suppression of the superconducting state due to the strong magnetic fields needed to observe the quantum Hall effect. From this point of view graphene is special since it allows the creation of strong pseudo-magnetic fields due to strain. We show that in a Josephson junction made of strained graphene, Cooper pairs will diffuse into the strained region. The pair correlation function will be sub-lattice polari...

  13. Stabilization of a histidine-producing strain of Serratia marcescens.

    Sugiura, M; Kisumi, M

    1984-01-01

    A decrease in histidine productivity was observed during subculture of a histidine-producing strain of Serratia marcescens. The decrease was accompanied by an increase in the number of wild-type revertants. Adenine accelerated the growth of producing strain HT-2892 to nearly equal that of revertants, and histidine production was stable because the depletion of ATP in strain HT-2892 was restored by adenine. To increase the intracellular ATP content, mutants resistant to 6-methylpurine, an anta...

  14. Complete genome sequence of Bacillus thuringiensis strain HD521

    Li, Qiao; Xu, Li Z.; Zou, Ting; Ai, Peng; Huang, Gang H.; Li, Ping; Zheng, Ai P.

    2015-01-01

    Bacillus thuringiensis is the most widely used biological pesticide in the world. It belongs to the Bacillus cereus sensu lato group, which contains six species. Among these six species, B. thuringiensis, B. anthracis, and B. cereus have a low genetic diversity. B. thuringiensis strain HD521 shows maroon colony which is different from most of the B. thuringiensis strains. Strain HD521 also displays an ability to inhibit plant sheath blight disease pathogen (Rhizoctonia solani AG1 IB) growth a...

  15. Genotypic comparison of Pantoea agglomerans plant and clinical strains

    Frey Jürg E

    2009-09-01

    Full Text Available Abstract Background Pantoea agglomerans strains are among the most promising biocontrol agents for a variety of bacterial and fungal plant diseases, particularly fire blight of apple and pear. However, commercial registration of P. agglomerans biocontrol products is hampered because this species is currently listed as a biosafety level 2 (BL2 organism due to clinical reports as an opportunistic human pathogen. This study compares plant-origin and clinical strains in a search for discriminating genotypic/phenotypic markers using multi-locus phylogenetic analysis and fluorescent amplified fragment length polymorphisms (fAFLP fingerprinting. Results Majority of the clinical isolates from culture collections were found to be improperly designated as P. agglomerans after sequence analysis. The frequent taxonomic rearrangements underwent by the Enterobacter agglomerans/Erwinia herbicola complex may be a major problem in assessing clinical associations within P. agglomerans. In the P. agglomerans sensu stricto (in the stricter sense group, there was no discrete clustering of clinical/biocontrol strains and no marker was identified that was uniquely associated to clinical strains. A putative biocontrol-specific fAFLP marker was identified only in biocontrol strains. The partial ORF located in this band corresponded to an ABC transporter that was found in all P. agglomerans strains. Conclusion Taxonomic mischaracterization was identified as a major problem with P. agglomerans, and current techniques removed a majority of clinical strains from this species. Although clear discrimination between P. agglomerans plant and clinical strains was not obtained with phylogenetic analysis, a single marker characteristic of biocontrol strains was identified which may be of use in strain biosafety determinations. In addition, the lack of Koch's postulate fulfilment, rare retention of clinical strains for subsequent confirmation, and the polymicrobial nature of P

  16. Sub-metre spatial resolution temperature compensated distributed strain sensor

    Belal, M.; Newson, T.P.

    2010-01-01

    We propose and demonstrate a scheme which utilizes the temperature dependence of spontaneous Raman scattering to provide temperature compensation for a sub-metre spatial resolution Brillouin frequency based strain sensor. Temperature compensated strain sensor measurements have been demonstrated with a strain resolution of 94?? and a spatial resolution of 10cms. This paper describes the combination of Brillouin frequency based BOCDA technique [1] with an independent measurement of temperature,...

  17. Identification of Potato Virus Y Strains in Tobacco Crops

    Jelena Zindović; Janoš Berenji; Milena Pauković; Ivana Đekić; Aleksandra Bulajić; Branka Krstić

    2007-01-01

    Five viruses: Potato Virus Y (PVY), Tomato Spotted Wilt Virus, Cucumber Mosaic Virus, Tobacco Mosaic Virus and Alfalfa Mosaic Virus, of which PVY was predominant, were detected by serological testing of tobacco samples collected from many localities in Vojvodina in 2006. Viruses are the most important pathogens in tobacco and PVY causes considerable economic damages all over the world. A PVY population comprises several different strain groups, strain subgroups and recombinant strains. Among ...

  18. Mechanical Control of Graphene on Engineered Pyramidal Strain Arrays

    Gill, Stephen T.; Hinnefeld, John H.; Zhu, Shuze; Swanson, William T.; Li, Teng; Mason, Nadya

    2015-01-01

    Strain can tune desirable electronic behavior in graphene, but there has been limited progress in controlling strain in graphene devices. In this paper, we study the mechanical response of graphene on substrates patterned with arrays of mesoscale pyramids. Using atomic force microscopy, we demonstrate that the morphology of graphene can be controlled from conformal to suspended depending on the arrangement of pyramids and the aspect ratio of the array. Non-uniform strains in graphene suspende...

  19. Twinning in copper deformed at high strain rates

    S Cronje; R E Kroon; W D Roos; J H Neethling

    2013-02-01

    Copper samples having varying microstructures were deformed at high strain rates using a split-Hopkinson pressure bar. Transmission electron microscopy results show deformation twins present in samples that were both annealed and strained, whereas samples that were annealed and left unstrained, as well as samples that were unannealed and strained, are devoid of these twins. These deformation twins occurred at deformation conditions less extreme than previously predicted.

  20. Preliminary result of Indonesian strain map based on geodetic measurements

    Susilo, Meilano, Irwan; Abidin, Hasanuddin Z.; Sapiie, Benyamin; Efendi, Joni; Wijanarto, Antonius B.

    2016-05-01

    GPS measurements from 1993 until 2014 across Indonesia region are providing longer time series at 2 - 3 millimetre-level precision from which surface velocity estimates are derived. In this study, we use this GPS velocities field to construct a crustal strain rate map and not including the physical model yet. In our preliminary result, we only compute the magnitude of the strain rate. The strain map is useful to construct the deformation model in Indonesia and to support the Indonesia datum.