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Sample records for planktothrix rubescens strain

  1. A genome-wide analysis of nonribosomal peptide synthetase gene clusters and their peptides in a Planktothrix rubescens strain

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    Nederbragt Alexander J

    2009-08-01

    Full Text Available Abstract Background Cyanobacteria often produce several different oligopeptides, with unknown biological functions, by nonribosomal peptide synthetases (NRPS. Although some cyanobacterial NRPS gene cluster types are well described, the entire NRPS genomic content within a single cyanobacterial strain has never been investigated. Here we have combined a genome-wide analysis using massive parallel pyrosequencing ("454" and mass spectrometry screening of oligopeptides produced in the strain Planktothrix rubescens NIVA CYA 98 in order to identify all putative gene clusters for oligopeptides. Results Thirteen types of oligopeptides were uncovered by mass spectrometry (MS analyses. Microcystin, cyanopeptolin and aeruginosin synthetases, highly similar to already characterized NRPS, were present in the genome. Two novel NRPS gene clusters were associated with production of anabaenopeptins and microginins, respectively. Sequence-depth of the genome and real-time PCR data revealed three copies of the microginin gene cluster. Since NRPS gene cluster candidates for microviridin and oscillatorin synthesis could not be found, putative (gene encoded precursor peptide sequences to microviridin and oscillatorin were found in the genes mdnA and oscA, respectively. The genes flanking the microviridin and oscillatorin precursor genes encode putative modifying enzymes of the precursor oligopeptides. We therefore propose ribosomal pathways involving modifications and cyclisation for microviridin and oscillatorin. The microviridin, anabaenopeptin and cyanopeptolin gene clusters are situated in close proximity to each other, constituting an oligopeptide island. Conclusion Altogether seven nonribosomal peptide synthetase (NRPS gene clusters and two gene clusters putatively encoding ribosomal oligopeptide biosynthetic pathways were revealed. Our results demonstrate that whole genome shotgun sequencing combined with MS-directed determination of oligopeptides successfully

  2. Impact of internal waves on the spatial distribution of Planktothrix rubescens (cyanobacteria) in an alpine lake.

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    Cuypers, Yannis; Vinçon-Leite, Brigitte; Groleau, Alexis; Tassin, Bruno; Humbert, Jean-François

    2011-04-01

    The vertical and horizontal distribution of the cyanobacterium, Planktothrix rubescens, was studied in a deep alpine lake (Lac du Bourget) in a 2-year monitoring program with 11 sampling points, and a 24-h survey at one sampling station. This species is known to proliferate in the metalimnic layer of numerous deep mesotrophic lakes in temperate areas, and also to produce hepatotoxins. When looking at the distribution of P. rubescens at the scale of the entire lake, we found large variations (up to 10  m) in the depth of the biomass peak in the water column. These variations were closely correlated to isotherm displacements. We also found significant variations in the distribution of the cyanobacterial biomass in the northern and southern parts of the lake. We used a physical modeling approach to demonstrate that two internal wave modes can explain these variations. Internal waves are generated by wind events, but can still be detected several days after the end of these events. Finally, our 24-h survey at one sampling point demonstrated that the V1H1 sinusoidal motion could evolve into nonlinear fronts. All these findings show that internal waves have a major impact on the distribution of P. rubescens proliferating in the metalimnic layer of a deep lake, and that this process could influence the growth of this species by a direct impact on light availability.

  3. Planktothrix Rubescens in Freshwater Reservoirs: The Sentinel-2 Potentiality for Mapping Phycocyanin Concentration

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    Maltese, Antonino; Capodici, Fulvio; Ciraolo, Giuseppe; Corbari, Chiara; Granata, Antonino; La Loggia, Goffredo

    2012-04-01

    In December 2006 blooms of Planktothrix rubescens were found in the Prizzi reservoir in Sicily. P. rubescens is sadly famous for producing microcystins (MC), which are harmful hepatotoxins. Recently (2006) P. rubescens has been found in the Pozzillo, Nicoletti, Ancipa, Prizzi and Garcia reservoirs. This paper compares the optical properties of the water of an infested reservoir and those of a clear water reservoir. Furthermore it evaluates an empirical method based on bands product to evaluate the phycocyanin cell density from MODIS, Landsat ETM+ and Sentinel-2 images. Spectroradiometric field campaigns were carried out in February/March 2008 to quantify the spectral transparencies of two water bodies through the calculation of the diffuse attenuation coefficient, by measuring underwater downwelling irradiance at different depths as well as water spectral reflectance. The possibility of detecting P. rubescens using its spectral characteristics through diachronic remote sensing techniques was investigated. During periods of low shortwave irradiance such as winter, when light weakly penetrates water columns and the water cools, P. rubescens filaments float up to the surface, forming red-colored blooms. Analyses were carried out on two reservoirs: Lake Prizzi and Lake Trinità, with and without the P. rubescens algal bloom respectively, during the acquisition of field data. Water samples were collected for both phytoplankton counting and biovolume estimation and for the analysis of MC. Meteorological measurements highlighted the low temperatures (blooms, and their concentration cannot be assessed accurately. When cyanobacteria dominate, the PC absorption is identified by a rising of spectral reflectance in red and near infrared spectral ranges. MODIS images have suitable spectral bands at a spatial resolution of 1 km that, however, is not suitable for lakes monitoring. A time series of MODIS images (spatial resolution of 250 m - red and near infrared bands) have been

  4. Appearance of Planktothrix rubescens Bloom with [D-Asp3, Mdha7]MC–RR in Gravel Pit Pond of a Shallow Lake-Dominated Area

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    Gábor Vasas

    2013-12-01

    Full Text Available Blooms of toxic cyanobacteria are well-known phenomena in many regions of the world. Microcystin (MC, the most frequent cyanobacterial toxin, is produced by entirely different cyanobacteria, including unicellular, multicellular filamentous, heterocytic, and non-heterocytic bloom-forming species. Planktothrix is one of the most important MC-producing genera in temperate lakes. The reddish color of cyanobacterial blooms viewed in a gravel pit pond with the appearance of a dense 3 cm thick layer (biovolume: 28.4 mm3 L−1 was an unexpected observation in the shallow lake-dominated alluvial region of the Carpathian Basin. [d-Asp3, Mdha7]MC–RR was identified from the blooms sample by MALDI-TOF and NMR. Concentrations of [d-Asp3, Mdha7]MC–RR were measured by capillary electrophoresis to compare the microcystin content of the field samples and the isolated, laboratory-maintained P. rubescens strain. In analyzing the MC gene cluster of the isolated P. rubescens strain, a deletion in the spacer region between mcyE and mcyG and an insertion were located in the spacer region between mcyT and mcyD. The insertion elements were sequenced and partly identified. Although some invasive tropical cyanobacterial species have been given a great deal of attention in many recent studies, our results draw attention to the spread of the alpine organism P. rubescens as a MC-producing, bloom-forming species.

  5. Unusual cohabitation and competition between Planktothrix rubescens and Microcystis sp. (cyanobacteria) in a subtropical reservoir (Hammam Debagh) located in Algeria.

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    Guellati, Fatma Zohra; Touati, Hassen; Tambosco, Kevin; Quiblier, Catherine; Humbert, Jean-François; Bensouilah, Mourad

    2017-01-01

    Succession in bloom-forming cyanobacteria belonging to distant functional groups in freshwater ecosystems is currently an undescribed phenomenon. However in the Hammam Debagh reservoir (Algeria), P. rubescens and Microcystis sp. co-occur and sometimes proliferate. With the aim of identifying the main factors and processes involved in this unusual cohabitation, water samples were collected monthly from February 2013 to June 2015 at the subsurface at four sampling stations and along the entire water column at one sampling station. In addition, the composition of the cyanobacterial communities was estimated by Illumina sequencing of a 16S rRNA gene fragment from samples collected over one year (October 2013-November 2014). This molecular approach showed that the Hammam Debagh reservoir displays high species richness (89 species) but very low diversity due to the high dominance of Microcystis in this community. Furthermore, it appears that Planktothrix rubescens and Microcystis sp. coexisted (from September to January) but proliferated alternately (Spring 2015 for P. rubescens and Spring 2014 and Autumn 2014/2015 for Microcystis). The main factors and processes explaining these changes in bloom-forming species seem to be related to the variation in the depth of the lake during the mixing period and to the water temperatures during the winter prior to the bloom season in spring.

  6. Management of a toxic cyanobacterium bloom (Planktothrix rubescens) affecting an Italian drinking water basin: a case study.

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    Bogialli, Sara; Nigro di Gregorio, Federica; Lucentini, Luca; Ferretti, Emanuele; Ottaviani, Massimo; Ungaro, Nicola; Abis, Pier Paolo; Cannarozzi de Grazia, Matteo

    2013-01-02

    An extraordinary bloom of Planktothrix rubescens, which can produce microcystins (MCs), was observed in early 2009 in the Occhito basin, used even as a source of drinking water in Southern Italy. Several activities, coordinated by a task force, were implemented to assess and manage the risk associated to drinking water contaminated by cyanobacteria. Main actions were: evaluation of analytical protocols for screening and confirmatory purpose, monitoring the drinking water supply chain, training of operators, a dedicated web site for risk communication. ELISA assay was considered suitable for health authorities as screening method for MCs and to optimize frequency of sampling according to alert levels, and as internal control for the water supplier. A liquid chromatography-tandem mass spectrometric method able to quantify 9 MCs was optimized with the aim of supporting health authorities in a comprehensive risk evaluation based on the relative toxicity of different congeners. Short, medium, and long-term corrective actions were implemented to mitigate the health risk. Preoxidation with chlorine dioxide followed by flocculation and settling have been shown to be effective in removing MCs in the water treatment plant. Over two years, despite the high levels of cyanobacteria (up to 160 × 10(6) cells/L) and MCs (28.4 μg/L) initially reached in surface waters, the drinking water distribution was never limited.

  7. Insights into the Planktothrix genus: Genomic and metabolic comparison of benthic and planktic strains.

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    Pancrace, Claire; Barny, Marie-Anne; Ueoka, Reiko; Calteau, Alexandra; Scalvenzi, Thibault; Pédron, Jacques; Barbe, Valérie; Piel, Joern; Humbert, Jean-François; Gugger, Muriel

    2017-01-24

    Planktothrix is a dominant cyanobacterial genus forming toxic blooms in temperate freshwater ecosystems. We sequenced the genome of planktic and non planktic Planktothrix strains to better represent this genus diversity and life style at the genomic level. Benthic and biphasic strains are rooting the Planktothrix phylogenetic tree and widely expand the pangenome of this genus. We further investigated in silico the genetic potential dedicated to gas vesicles production, nitrogen fixation as well as natural product synthesis and conducted complementary experimental tests by cell culture, microscopy and mass spectrometry. Significant differences for the investigated features could be evidenced between strains of different life styles. The benthic Planktothrix strains showed unexpected characteristics such as buoyancy, nitrogen fixation capacity and unique natural product features. In comparison with Microcystis, another dominant toxic bloom-forming genus in freshwater ecosystem, different evolutionary strategies were highlighted notably as Planktothrix exhibits an overall greater genetic diversity but a smaller genomic plasticity than Microcystis. Our results are shedding light on Planktothrix evolution, phylogeny and physiology in the frame of their diverse life styles.

  8. Recombination and selectional forces in cyanopeptolin NRPS operons from highly similar, but geographically remote Planktothrix strains

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    Kristensen Tom

    2008-08-01

    Full Text Available Abstract Background Cyanopeptolins are nonribosomally produced heptapetides showing a highly variable composition. The cyanopeptolin synthetase operon has previously been investigated in three strains from the genera Microcystis, Planktothrix and Anabaena. Cyanopeptolins are displaying protease inhibitor activity, but the biological function(s is (are unknown. Cyanopeptolin gene cluster variability and biological functions of the peptide variants are likely to be interconnected. Results We have investigated two cyanopeptolin gene clusters from highly similar, but geographically remote strains of the same genus. Sequencing of a nonribosomal peptide synthetase (NRPS cyanopeptolin gene cluster from the Japanese strain Planktothrix NIES 205 (205-oci, showed the 30 kb gene cluster to be highly similar to the oci gene cluster previously described in Planktothrix NIVA CYA 116, isolated in Norway. Both operons contained seven NRPS modules, a sulfotransferase (S and a glyceric acid loading (GA-domain. Sequence analyses showed a high degree of conservation, except for the presence of an epimerase domain in NIES 205 and the regions around the epimerase, showing high substitution rates and Ka/Ks values above 1. The two strains produce almost identical cyanopeptolins, cyanopeptolin-1138 and oscillapeptin E respectively, but with slight differences regarding the production of minor cyanopeptolin variants. These variants may be the result of relaxed adenylation (A-domain specificity in the nonribosomal enzyme complex. Other genetic markers (16S rRNA, ntcA and the phycocyanin cpcBA spacer were identical, supporting that these geographically separated Planktothrix strains are closely related. Conclusion A horizontal gene transfer event resulting in exchange of a whole module-encoding region was observed. Nucleotide statistics indicate that both purifying selection and positive selection forces are operating on the gene cluster. The positive selection forces are

  9. Assessment of the Effects of Light Availability on Growth and Competition Between Strains of Planktothrix agardhii and Microcystis aeruginosa

    NARCIS (Netherlands)

    Torres, Camila de Araujo; Lurling, Miquel; Marinho, Marcelo Manzi

    In this study, we tested the hypothesis that Planktothrix agardhii strains isolated from a tropical water body were better competitors for light than Microcystis aeruginosa strains. These cyanobacteria are common in eutrophic systems, where light is one of the main drivers of phytoplankton, and

  10. Evolution of Anabaenopeptin Peptide Structural Variability in the Cyanobacterium Planktothrix

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    Entfellner, Elisabeth; Frei, Mark; Christiansen, Guntram; Deng, Li; Blom, Jochen; Kurmayer, Rainer

    2017-01-01

    Cyanobacteria are frequently involved in the formation of harmful algal blooms wherein, apart from the toxic microcystins, other groups of bioactive peptides are abundant as well, such as anabaenopeptins (APs). The APs are synthesized nonribosomally as cyclic hexapeptides with various amino acids at the exocyclic position. We investigated the presence and recombination of the AP synthesis gene cluster (apnA-E) through comparing 125 strains of the bloom-forming cyanobacterium Planktothrix spp., which were isolated from numerous shallow and deep water habitats in the temperate and tropical climatic zone. Ten ecologically divergent strains were purified and genome sequenced to compare their entire apnA-E gene cluster. In order to quantify apn gene distribution patterns, all the strains were investigated by PCR amplification of 2 kbp portions of the entire apn gene cluster without interruption. Within the 11 strains assigned to P. pseudagardhii, P. mougeotii, or P. tepida (Lineage 3), neither apnA-E genes nor remnants were observed. Within the P. agardhii/P. rubescens strains from shallow waters (Lineage 1, 52 strains), strains both carrying and lacking apn genes occurred, while among the strains lacking the apnA-E genes, the presence of the 5′end flanking region indicated a gene cluster deletion. Among the strains of the more derived deep water ecotype (Lineage 2, 62 strains), apnA-E genes were always present. A high similarity of apn genes of the genus Planktothrix when compared with strains of the genus Microcystis suggested its horizontal gene transfer during the speciation of P. agardhii/P. rubescens. Genetic analysis of the first (A1-) domain of the apnA gene, encoding synthesis of the exocyclic position of the AP molecule, revealed four genotype groups that corresponded with substrate activation. Groups of genotypes were either related to Arginine only, the coproduction of Arginine and Tyrosine or Arginine and Lysine, or even the coproduction of Arginine

  11. [ADMAdda5]-microcystins in Planktothrix agardhii strain PH-123 (cyanobacteria) -  importance for monitoring of microcystins in the environment

    DEFF Research Database (Denmark)

    Laub, J.; Henriksen, P.; Brittain, S.M.

    2002-01-01

    major microcystins contained an acetyl-demethyl variant (ADMAdda) of 3-amino-9-acetoxy-2,6,8-trimethyl-10-phenyldeca-4,6-dienoic acid (Adda). This is the first report of [ADMAdda5]-microcystins in Planktothrix. The two [ADMAdda5]-microcystins inhibited protein phosphatase activity but showed low cross...

  12. 冬凌草内生细菌的分离鉴定及其对植物病害的生防作用%Isolation & Identification of Entophytic Bacterial Strain from Rabdosia rubescens & Its Biocontrol Effects against Plant Pathogens

    Institute of Scientific and Technical Information of China (English)

    柯杨; 马瑜; 沈莹华; 李勃

    2013-01-01

    An enlophylic bacterial strain KD3 isolated from the tissue of Rabdosia rubescens ( Hemsl. ) H. Hara obviously had antagonism against many crop fungal pathogens. This strain was identified as Bacillus sublilis according to its morphological, physiological and biochemical characteristics and 16S rRNA sequence analysis. The results of antagonism test showed that strain KD3 could control the plant pathogens effectively, which exhibited a good application and development potential.%从冬凌草(Rabdosia rubescens (Hemsl.) H.Hara)中分离筛选出1株对多种作物真菌病害具有显著拮抗作用的细菌,命名为KD3.通过其形态特征和生理生化特性以及16S rRNA序列的同源性分析,鉴定该菌株为枯草芽胞杆菌(Bacillus subtilis).试验表明,KD3菌株能够显著抑制多种病原真菌的侵染,具有良好的应用开发潜力.

  13. Evaluating the influence of light intensity in mcyA gene expression and microcystin production in toxic strains of Planktothrix agardhii and Microcystis aeruginosa.

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    Salvador, Daniel; Churro, Catarina; Valério, Elisabete

    2016-04-01

    Cyanobacteria are phytoplanktonic organisms widely occurring in freshwaters, being frequently associated with the production of toxins, namely microcystins (MCs). MCs are produced non-ribosomally by a multienzyme complex (mcy genes). It has been reported that environmental factors, such as light intensity, can influence toxin production. The aim of this study was to assess the influence of light intensity in the transcription of the mcyA gene and corresponding production of microcystins in toxic isolates of Planktothrix agardhii, where little is known, and compare them to Microcystis aeruginosa. For that purpose, cultures were exposed to three different light intensities (4, 20 and 30 μmol photons m(-2) s(-1)) for 18 days at 20 ± 1 °C. The growth was followed daily using absorbance readings. Samples were collected at each growth stage for cell counting, microcystins quantification and RNA extraction. The level of transcripts was quantified by RT-qPCR and the relative expression determined using 16S rDNA, gltA and rpoC1 as reference genes. The most stable reference genes in M. aeruginosa were rpoC1 and gltA, whereas in P. agardhii were 16S rDNA and gltA. There was a correspondence between the growth rate and light intensity in M. aeruginosa and P. agardhii. The growth rates for both species were lower at 4 and higher at 30 μmol photons m(-2) s(-1). Microcystin concentration per cell was similar between light intensities in M. aeruginosa and over time, while in P. agardhii it was higher in the stationary phase at 4 μmol photons m(-2) s(-1). There were differences in the expression of mcyA between the two species. In M. aeruginosa, the highest levels of expression occurred at 4 μmol photons m(-2) s(-1) in the adaptation phase, whereas for P. agardhii it was at 4μmol photons m(-2) s(-1) in the exponential growth phase. Our results indicate that the light intensities tested had distinct influences on the growth, microcystin production and mcyA expression levels

  14. Analysis of Volatile Components in Wild Strains of Rabdosia rubescens in Jiyuan Area%济源地区野生品系冬凌草中挥发性成分分析

    Institute of Scientific and Technical Information of China (English)

    李高申; 刘文; 张伟; 郭梅珍; 尹震花

    2016-01-01

    目的:分析济源地区野生品系冬凌草中的挥发性成分.方法:采用顶空固相微萃取(HS-SPME)法对河南省济源地区43种野生冬凌草地上部分中的挥发性成分进行提取,采用气相色谱-质谱联用(GC-MS)法检测成分,采用面积归一化法计算各成分的相对含量.结果:43种野生冬凌草挥发性成分的种类和相对含量具有明显差异,种类在0~11种之间,相对含量在0~84.03%之间;石竹烯、石竹烯氧化物、二氢猕猴桃内酯、植酮和百秋李醇在多种不同品系野生冬凌草的挥发性成分中存在,是其主要成分;其挥发性成分的主要结构类型由萜烯类、酮类、醇类和酯类组成,此外在个别品系冬凌草中还含有少量的脂肪酸类,如棕榈酸、油酸和亚油酸.结论:济源地区不同品系野生冬凌草内在质量存在一定差异.%OBJECTIVE:To analysis the volatile components in wild strains of Rabdosia rubescensin in Jiyuan area. METH-ODS:Headspace solid phase microextraction (HS-SPME) was conducted to extract the volatile components in 43 wild species of R. rubescens,GC-MS was conducted to identify the components,and peak area normalization method was conducted to calculate the relative content of the components. RESULTS:The variety and relative contents of the volatility components in 43 wild species had obvious differences and the ranges of species number and relative content was from 0 to 11 and from 0 to 84.03% respectively. Caryophyllene,caryophyllene oxide,dihydroactinidiolide,phytone and patchouli alcohol were main components which existed in a variety of different strains of volatile components of R. rubescens,and were mainly composed of terpenes,ketones,alcohols and es-ters. In addition,fatty acids such as palmitic acid,oleic acid and linoleic acid were contained in a few individual varieties. CON-CLUSIONS:The internal quality in 43 wild species of R. rubescens has certain differences.

  15. The Red Queen race between parasitic chytrids and their host, Planktothrix: a test using a time series reconstructed from sediment DNA.

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    Marcia Kyle

    Full Text Available Parasitic chytrid fungi (phylum Chytridiomycota are known to infect specific phytoplankton, including the filamentous cyanobacterium Planktothrix. Subspecies, or chemotypes of Planktothrix can be identified by the presence of characteristic oligopeptides. Some of these oligopeptides can be associated with important health concerns due to their potential for toxin production. However, the relationship between chytrid parasite and Planktothrix host is not clearly understood and more research is needed. To test the parasite-host relationship over time, we used a sediment core extracted from a Norwegian lake known to contain both multiple Planktothrix chemotype hosts and their parasitic chytrid. Sediment DNA of chytrids and Planktothrix was amplified and a 35-year coexistence was found. It is important to understand how these two antagonistic species can coexistence in a lake. Reconstruction of the time series showed that between 1979-1990 at least 2 strains of Planktothrix were present and parasitic pressure exerted by chytrids was low. After this period one chemotype became dominant and yet showed continued low susceptibility to chytrid parasitism. Either environmental conditions or intrinsic characteristics of Planktothrix could have been responsible for this continued dominance. One possible explanation could be found in the shift of Planktothrix to the metalimnion, an environment that typically consists of low light and decreased temperatures. Planktothrix are capable of growth under these conditions while the chytrid parasites are constrained. Another potential explanation could be due to the differences between cellular oligopeptide variations found between Planktothrix chemotypes. These oligopeptides can function as defense systems against chytrids. Our findings suggest that chytrid driven diversity was not maintained over time, but that the combination of environmental constraints and multiple oligopeptide production to combat chytrids

  16. The Red Queen race between parasitic chytrids and their host, Planktothrix: a test using a time series reconstructed from sediment DNA.

    Science.gov (United States)

    Kyle, Marcia; Haande, Sigrid; Ostermaier, Veronika; Rohrlack, Thomas

    2015-01-01

    Parasitic chytrid fungi (phylum Chytridiomycota) are known to infect specific phytoplankton, including the filamentous cyanobacterium Planktothrix. Subspecies, or chemotypes of Planktothrix can be identified by the presence of characteristic oligopeptides. Some of these oligopeptides can be associated with important health concerns due to their potential for toxin production. However, the relationship between chytrid parasite and Planktothrix host is not clearly understood and more research is needed. To test the parasite-host relationship over time, we used a sediment core extracted from a Norwegian lake known to contain both multiple Planktothrix chemotype hosts and their parasitic chytrid. Sediment DNA of chytrids and Planktothrix was amplified and a 35-year coexistence was found. It is important to understand how these two antagonistic species can coexistence in a lake. Reconstruction of the time series showed that between 1979-1990 at least 2 strains of Planktothrix were present and parasitic pressure exerted by chytrids was low. After this period one chemotype became dominant and yet showed continued low susceptibility to chytrid parasitism. Either environmental conditions or intrinsic characteristics of Planktothrix could have been responsible for this continued dominance. One possible explanation could be found in the shift of Planktothrix to the metalimnion, an environment that typically consists of low light and decreased temperatures. Planktothrix are capable of growth under these conditions while the chytrid parasites are constrained. Another potential explanation could be due to the differences between cellular oligopeptide variations found between Planktothrix chemotypes. These oligopeptides can function as defense systems against chytrids. Our findings suggest that chytrid driven diversity was not maintained over time, but that the combination of environmental constraints and multiple oligopeptide production to combat chytrids could have allowed one

  17. Two New Diterpenoids from Isodon rubescens

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Two new diterpenoids taibairubescensin A (1) and B (2) have been isolated from Isodon rubescens.The structures of compound 1 and 2 were elucidated as 2b ,3b -diacetoxy-11b ,13a -dihydroxy-ent-kaur-16-en-15-one (1) and 3b ,11b -diacetoxy-2b ,6a -dihydroxy-ent-kaur-16-en-15-one (2) on the basis of spectroscopic analysis.

  18. Low antiplasmodial activity of alkaloids and amides from the stem bark of Zanthoxylum rubescens (Rutaceae

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    Penali L.

    2007-06-01

    Full Text Available The stem bark of Zanthoxylum rubescens (syn. Fagara rubescens is used for treating fevers associated with malaria in the Ivory Coast. Three alkaloids: N-nornitidine, 7,9-dimethoxy-2,3- methylenedioxybenzophenanthridine, and bis[6-(5,6- dihydrochelerythrinyl] ether; and two amides: zanthomamide and lemairamide, were isolated from the stem bark of this plant. These compounds were screened in vitro against the chloroquine-sensitive 3D7 strain and the chloroquine-resistant FCM29 strain of P. falciparum. N-nornitidine was found to be inactive. 7,9- dimethoxy-2,3-methylenedioxybenzophenanthridine, lemairamide and zanthomamide showed weak activity with average IC50 values ranging from 45.6 μM to 149.9 μM. Bis[6-(5,6- dihydrochelerythrinyl] ether was the most active of the tested compounds with mean IC50s of 14.9 ± 1.4 μM in FCM29 strain and 15.3 ± 3.4 μM in 3D7 strain (~ 58 to ~ 1130 times less active than chloroquine respectively. The anti-Plasmodium activities of the tested alkaloids of Z. rubescens were low; and do not encourage the use of this plant as antimalarial.

  19. Efficacy of Rabdosia Rubescens in the Treatment of Gingivitis

    Institute of Scientific and Technical Information of China (English)

    Sui CHEN; Jiarong LIU; Handong ZHANG

    2009-01-01

    This study evaluated the efficacy ofrabdosia rubescens against gingivitis and compared the therapeutic efficacy of different dosage forms of rabdosia rubescens. A multi-center, randomized, dou-ble-blind, double-simulation, positive-controlled and parallel trial was conducted. A total of 136 patients exhibiting clinical symptoms of gingivitis were enrolled. The subjects were randomly assigned to two groups: test group (n=67), in which rabdosia rubescens drop pill (960 mg) and 4 tablets of simulation agent of rabdosia rubescen were orally given to the subjects three times a day for 5 days; and control group (n=69), in which the subjects were administered the tablets of rabdosia rubescens (1000 mg) and 24 drop pills of simulation agent of rabdosia rubescens thrice daily for 5 days. The experimental proto-cols and diagnostic criteria were established by expert panel prior to the experiment. The clinical symp-toms were graded according to the severity of the disease and quantified. The total scores and scores for each clinical symptom of gingivitis were assessed at baseline and on the 6th day post-treatment. The therapeutic efficacy was compared between the two groups and in each group itself before and after the treatment. The results showed that in the two groups, the subjects who were given rabdosia rubescens,drop pill or tablet, had a decrease in total scores and scores for each clinical symptom when compared with those before treatment (P<0.01). There was significant difference in the therapeutic efficacy be-tween the test group and the control group with the efficacy rate being 92.54% and 79.71% respectively (P<0.05). It was concluded that rabdosia rubescens showed great promise in treating gingivitis. And rabdosia rubescens drop pill was more efficacious than rabdosia rubescens tablet.

  20. Antibacterial Activities and Mechanism of Action of Acetone Extracts from Rabdosia rubescens

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    Li Ping Cheng

    2014-12-01

    Full Text Available The antibacterial activities and mechanism of action of acetone extracts from R. rubescens were reported in this paper. The results showed that 80% acetone extracts had both the highest contents of total phenolics and flavonoids. Acetone extracts showed better antibacterial activities against Gram-positive bacterial strains and there were no inhibitory effects found on tested Gram-negative bacteria. In addition, 80% acetone extracts from R. rubescens had relatively higher antibacterial activities with the lowest values of MIC and MBC at 2.5 mg/mL and 5 mg/mL against B. subtilis. The antibacterial mechanism of 80% acetone extracts against Bacillus subtilis might be described as disrupting cell wall, increasing cell membrane permeability, and finally leading to the leakage of cell constituents

  1. Physiological Changes Within a Metalimnetic Layer of Oscillatoria rubescens

    OpenAIRE

    Konopka, Allan

    1980-01-01

    Different depths within a metalimnetic layer of Oscillatoria rubescens were sampled, and changes in biochemical composition and photosynthetic rate were analyzed. Although differences in pigment and protein content were found, the photosynthetic rates of the samples were not significantly different.

  2. MIB-producing cyanobacteria (Planktothrix sp.) in a drinking water reservoir: distribution and odor producing potential.

    Science.gov (United States)

    Su, Ming; Yu, Jianwei; Zhang, Junzhi; Chen, Hui; An, Wei; Vogt, Rolf D; Andersen, Tom; Jia, Dongmin; Wang, Jingshi; Yang, Min

    2015-01-01

    The production of odorant 2-methylisoborneol (MIB) in water bodies by Planktothrix sp. have not been understood very well. Through a four-year investigation in Miyun Reservoir, a huge mesotrophic drinking water reservoir known to have the MIB episodes, we found that the Planktothrix sp. bloomed during September and October causing the high levels of MIB in the reservoir. The concentration of MIB and the biomass of MIB-producing cyanobacteria Planktothrix were measured (n = 887) at different sites and depths during different seasons. The results indicated that the shallow region of the reservoir is the major habitat for Planktothrix sp. due to that the light is able to penetrate down to the relatively high concentrations of nutrients close to the sediments. Quantile regression analysis between Planktothrix biomass and MIB concentration shows that the risk of MIB exceeding the odor threshold (15 ng L⁻¹) in water was as high as 90% when the Planktothrix density was more than 4.0 × 10⁵ cells L⁻¹, while the risk was reduced to 10% when the Planktothrix density remained below 1.6 × 10⁴ cells L⁻¹. This study will improve the understanding of the environmental behaviors of Planktothrix sp., and can provide useful information for better management of drinking water lakes/reservoirs experiencing the taste and odor (T&O) problems caused by deep living cyanobacterial species.

  3. Contrasting microcystin production and cyanobacterial population dynamics in two Planktothrix dominated freshwater lakes

    NARCIS (Netherlands)

    Janse, I.; Kardinaal, W.E.A.; Kamst-van Agterveld, M.P.; Meima, M.; Visser, P.M.; Zwart, G.

    2005-01-01

    Microcystin concentrations in two Dutch lakes with an important Planktothrix component were related to the dynamics of cyanobacterial genotypes and biovolumes. Genotype composition was analysed by using denaturing gradient gel electrophoresis (DGGE) profiling of the intergenic transcribed spacer reg

  4. Temperature Effect on Exploitation and Interference Competition among Microcystis aeruginosa, Planktothrix agardhii and, Cyclotella meneghiniana

    Directory of Open Access Journals (Sweden)

    Andreia Maria da Anunciação Gomes

    2015-01-01

    Full Text Available We studied the effect of temperature (18 and 30°C on growth and on the exploitation and interference competition of three species: Microcystis aeruginosa (MIJAC, Planktothrix agardhii (PAT, and Cyclotella meneghiniana (CCAP. Coculturing the organisms in batch systems allowed for the examination of both competitive interactions, while the interference competition was studied in cross-cultures. The experiments were done during 10–12 days, and samples were taken for chlorophyll-a analysis, using PHYTO-PAM. The temperature did not influence exploitation competition between MIJAC and other competitors and it was the best competitor in both temperatures. PAT presented higher growth rates than CCAP in competition at 18 and 30°C. The temperature influenced the interference competition. The growth of MIJAC was favored in strains exudates at 30°C, while CCAP was favored at 18°C, revealing that the optimum growth temperature was important to establish the competitive superiority. Therefore, we can propose two hypotheses: (i different temperatures may results in production of distinct compounds that influence the competition among phytoplankton species and (ii the target species may have different vulnerability to these compounds depending on the temperature. At last, we suggest that both the sensitivity and the physiological status of competing species can determine their lasting coexistence.

  5. Temperature Effect on Exploitation and Interference Competition among Microcystis aeruginosa, Planktothrix agardhii and, Cyclotella meneghiniana.

    Science.gov (United States)

    Gomes, Andreia Maria da Anunciação; de Oliveira e Azevedo, Sandra Maria Feliciano; Lürling, Miquel

    2015-01-01

    We studied the effect of temperature (18 and 30°C) on growth and on the exploitation and interference competition of three species: Microcystis aeruginosa (MIJAC), Planktothrix agardhii (PAT), and Cyclotella meneghiniana (CCAP). Coculturing the organisms in batch systems allowed for the examination of both competitive interactions, while the interference competition was studied in cross-cultures. The experiments were done during 10-12 days, and samples were taken for chlorophyll-a analysis, using PHYTO-PAM. The temperature did not influence exploitation competition between MIJAC and other competitors and it was the best competitor in both temperatures. PAT presented higher growth rates than CCAP in competition at 18 and 30°C. The temperature influenced the interference competition. The growth of MIJAC was favored in strains exudates at 30°C, while CCAP was favored at 18°C, revealing that the optimum growth temperature was important to establish the competitive superiority. Therefore, we can propose two hypotheses: (i) different temperatures may results in production of distinct compounds that influence the competition among phytoplankton species and (ii) the target species may have different vulnerability to these compounds depending on the temperature. At last, we suggest that both the sensitivity and the physiological status of competing species can determine their lasting coexistence.

  6. A New Asymmetric ent-Kauranoid Dimer from Rabdosia rubescens

    Institute of Scientific and Technical Information of China (English)

    LU Hai-ying; LIANG Jing-yu

    2012-01-01

    Objective To study the ent-kaurane diterpenoids from Rabdosia rubescens.Methods The compounds were isolated by chromatographies and their structures were identified by spectral analyses.Results Four compounds were isolated,and they were identified as bisrubescensin E (1),2α,3α,24-trihydroxyurs-12-en-28-oic acid (2),2α,3α,24-trihydroxyurs-12,20-(30)-dien-28-oic acid (3),and 6,7-dihydroxycoumarin (4).Conclusion Compound 1 is a new asymmetric ent-kauranoid dimer.Compound 2 is isolated from the plant for the first time.Compounds 3 and 4 are isolated from the plants ofRabdosia (B1.) Hassk for the first time.

  7. Influence of Temperature, Oxygen, and pH on a Metalimnetic Population of Oscillatoria rubescens.

    Science.gov (United States)

    Konopka, A

    1981-07-01

    Planktonic Oscillatoria spp. often inhabit depths of thermally stratified lakes in which gradients of physical and chemical factors occur. Measurements of photosynthetic rate or photosynthetic carbon metabolism were used to evaluate the importance of vertical gradients of temperature, oxygen, and pH upon Oscillatoria rubescens in Crooked Lake, Ind. At the low light intensities experienced in situ, neither photosynthetic rate nor relative incorporation of carbon dioxide into low-molecular-weight compounds, polysaccharide, or protein was affected by temperature. At a 10-fold-higher light intensity, the photosynthetic rate increased as temperature increased; most of the additional carbon accumulated as polysaccharide. Polysaccharide which was synthesized at high light intensity and temperature was respired when the organisms were placed in the dark, but was not used for protein biosynthesis. When O. rubescens was shifted from high light to low light, a fraction of the polysaccharide was metabolized into protein. Adaptation to growth at lower temperatures by O. rubescens cultures resulted in a decrease in the maximum photosynthetic rate. Oxygen inhibited photosynthesis by only 10 to 15% at concentrations typically found in the lake. The photosynthetic rates at pH values which occurred in Crooked Lake were all near the maximum. Thus, gradients of temperature, oxygen, or pH are not likely to significantly affect the distribution of O. rubescens in Crooked Lake, given the low light intensity at which O. rubescens grows and the range of values for those factors in the lake.

  8. Sprectroradiometric characteristics of inland water bodies infestated by Oscillatoria rubescens algae

    Science.gov (United States)

    Ciraolo, Giuseppe; La Loggia, Goffredo; Maltese, Antonino

    2010-10-01

    In December 2006 blooms of Oscillatoria rubescens were found in the reservoir Prizzi in Sicily. Oscillatoria is a genus of filamentous alga comprising approximately 6 species, between these the O. rubescens is sadly famous since this organism produces microcystins which are powerful hepatotoxins. Firstly found in Europe in 1825 on Geneva lake, recently (2006) those algae has been find out in Pozzillo, Nicoletti e Ancipa reservoirs (Enna Province), as well as in Prizzi (Palermo Province) and Garcia reservoirs (Trapani Province). Toxins produced by those bacteria (usually called microcystine LR-1 and LR-2) are highly toxic since they can activate oncogenes cells causing cancer pathologies on liver and gastrointestinal tract. Even if water treatment plants should ensure the provision of safe drinking water from surface waters contaminated with those toxic algae blooms, the contamination of reservoirs used for civil and agricultural supply highlights human health risks. International literature suggests a threshold value of 0.01 μgl-1 to avoid liver cancer using water coming from contaminated water bodies for a long period. Since O. rubescens activities is strongly related to phosphate and nitrogen compounds as well as to temperature and light transmission within water, the paper presents the comparison between optical properties of the water of an infested reservoir and those of a reservoir characterized by clear water. Field campaigns were carried out in February-March 2008 in order to quantify the spectral transparencies of two water bodies through the calculation of the diffuse attenuation coefficient, measuring underwater downwelling irradiance at different depths as well as water spectral reflectance. Results show that diffuse attenuation coefficient is reduced by approximately 15% reducing light penetration in the water column; coherently reflectance spectral signature generally decreases, exhibiting a characteristic peak around 703 nm not present in

  9. Influence of Temperature, Oxygen, and pH on a Metalimnetic Population of Oscillatoria rubescens

    OpenAIRE

    Konopka, Allan

    1981-01-01

    Planktonic Oscillatoria spp. often inhabit depths of thermally stratified lakes in which gradients of physical and chemical factors occur. Measurements of photosynthetic rate or photosynthetic carbon metabolism were used to evaluate the importance of vertical gradients of temperature, oxygen, and pH upon Oscillatoria rubescens in Crooked Lake, Ind. At the low light intensities experienced in situ, neither photosynthetic rate nor relative incorporation of carbon dioxide into low-molecular-weig...

  10. Simultaneous characterization and quantification of 17 main compounds in Rabdosia rubescens by high performance liquid chromatography

    Directory of Open Access Journals (Sweden)

    Sen Guo

    2017-04-01

    Full Text Available Rabdosia rubescens is a healthy herbal tea and well-known Chinese medicinal herb. To evaluate the quality of R. rubescens from China, a high performance liquid chromatography method with dual-wavelength detection was developed and validated. The method was successfully applied for the simultaneous characterization and quantification of 17 main constituents from four different cultivation regions in China. Under optimal conditions, analysis was performed on a Luna C-18 column and gradient elution with a solvent system of acetonitrile and 0.5% (v/v acetic acid–water at a flow rate of 1.0 mL/min and wavelength of 220 nm and 280 nm. All standard calibration curves exhibited good linearity (r2 > 0.9992 within the test ranges. The precision was evaluated by intraday and interday tests, which revealed relative standard deviation values within the ranges of 0.57–2.35% and 0.52–3.40%, respectively. The recoveries were in the range of 96.37–101.66%. The relative standard deviation values for stability and repeatability were < 5%. The contents of some compounds were low and varied with different cultivars. The proposed method could serve as a prerequisite for quality control of R. rubescens materials and products.

  11. Analysis of the transcriptome of Isodon rubescens and key enzymes involved in terpenoid biosynthesis

    Directory of Open Access Journals (Sweden)

    Xiuhong Su

    2016-05-01

    Full Text Available Isodon rubescens is an important medicinal plant in China that has been shown to reduce tumour growth due to the presence of the compound oridonin. In an effort to facilitate molecular research on oridonin biosynthesis, we reported the use of next generation massively parallel sequencing technologies and de novo transcriptome assembly to gain a comprehensive overview of I. rubescens transcriptome. In our study, a total of 50,934,276 clean reads, 101,640 transcripts and 44,626 unigenes were generated through de novo transcriptome assembly. A number of unigenes – 23,987, 10,263, 7359, 18,245, 17,683, 19,485, 9361 – were annotated in the National Center for Biotechnology Information (NCBI non-redundant protein (Nr, NCBI nucleotide sequences (Nt, Kyoto Encyclopedia of Genes and Genomes (KEGG Orthology (KO, Swiss-Prot, protein family (Pfam, gene ontology (GO, eukaryotic ortholog groups (KOG databases, respectively. Furthermore, the annotated unigenes were functionally classified according to the GO, KOG and KEGG. Based on these results, candidate genes encoding enzymes involved in terpenoids backbone biosynthesis were detected. Our data provided the most comprehensive sequence resource available for the study on I. rubescens, as well as demonstrated the effective use of Illumina sequencing and de novo transcriptome assembly on a species lacking genomic information.

  12. Ciliate Nassula sp. grazing on a microcystin-producing cyanobacterium (Planktothrix agardhii): impact on cell growth and in the microcystin fractions

    Energy Technology Data Exchange (ETDEWEB)

    Combes, Audrey; Dellinger, Marc [' Molecules de communication et adaptation des microorganismes' , UMR 7245 CNRS-MNHN, Museum national d' Histoire naturelle, CP 39, 57 rue Cuvier, F-75231 Paris Cedex 05 (France); Cadel-six, Sabrina [' Unite Caracterisation des Toxines' - Laboratoire de securite des aliments de Maisons-Alfort - ANSES, F-94701 Maisons Alfort Cedex (France); Amand, Severine [' Molecules de communication et adaptation des microorganismes' , UMR 7245 CNRS-MNHN, Museum national d' Histoire naturelle, CP 39, 57 rue Cuvier, F-75231 Paris Cedex 05 (France); Comte, Katia, E-mail: kcomte@mnhn.fr [' Molecules de communication et adaptation des microorganismes' , UMR 7245 CNRS-MNHN, Museum national d' Histoire naturelle, CP 39, 57 rue Cuvier, F-75231 Paris Cedex 05 (France)

    2013-01-15

    The proliferation of microcystins (MCs)-producing cyanobacteria (MCs) can have detrimental effects on the food chain in aquatic environments. Until recently, few studies had focused on the fate of MCs in exposed organisms, such as primary consumers of cyanobacteria. In this study, we investigate the impact of an MC-producing strain of the cyanobacterium Planktothrix agardhii on the growth and physiology of a Nassula sp. ciliate isolated from a non-toxic cyanobacterial bloom. We show that this Nassula sp. strain was able to consume and grow while feeding exclusively on an MC-producing cyanobacterium over a prolonged period of time (8 months). In short-term exposure experiments (8 days), ciliates consuming an MC-producing cyanobacterial strain displayed slower growth rate and higher levels of antioxidant enzymes than ciliates feeding on two non-MC-producing strains. Three high-performance methods (LC/MS, LC/MS-MS and ELISA) were used to quantify the free and bound MCs in the culture medium and in the cells. We show that ciliate grazing led to a marked decrease in free MCs (methanol extractable) in cells, the MCs were therefore no longer found in the surrounding culture medium. These findings suggest that MCs may have undergone redistribution (free vs bound MCs) or chemical degradation within the ciliates.

  13. Pulsed nitrogen supply induces dynamic changes in the amino acid compositionand microcystin production of the harmful cyanobacterium Planktothrix agardhii

    NARCIS (Netherlands)

    Van de Waal, D.B.; Ferreruela, G.; Tonk, L.; Van Donk, E.; Huisman, J.; Visser, P.M.; Matthijs, H.C.P.

    2010-01-01

    Planktothrix agardhii is a widespread harmful cyanobacterium of eutrophic waters, and can produce the hepatotoxins [Asp3]microcystin-LR and [Asp3]microcystin-RR. These two microcystin variants differ in their first variable amino acid position, which is occupied by either leucine (L) or arginine (R)

  14. Pulsed nitrogen supply induces dynamic changes in the amino acid composition and microcystin production of the harmful cyanobacterium Planktothrix agardhii

    NARCIS (Netherlands)

    van de Waal, D.B.; Ferreruela, G.; Tonk, L.; van Donk, E.; Huisman, J.; Visser, P.M.; Matthijs, H.C.P.

    2010-01-01

    Planktothrix agardhii is a widespread harmful cyanobacterium of eutrophic waters, and can produce the hepatotoxins [Asp3]microcystin-LR and [Asp3]microcystin-RR. These two microcystin variants differ in their first variable amino acid position, which is occupied by either leucine (L) or arginine (R)

  15. Effects of the Rabdosia rubescens total flavonoids on focal cerebral ischemia reperfusion model in rats

    Directory of Open Access Journals (Sweden)

    Mingsan Miao

    2017-05-01

    Full Text Available The effect of the Rabdosia rubescens total flavonoids on focal cerebral ischemia reperfusion model in rats was observed. The model group, nimodipine group, cerebral collateral group, and large, medium and small dose group of the Rabdosia rubescens total flavonoids were administered with corresponding drugs but sham operation group and model group were administered the same volume of 0.5%CMC, 1 times a day, continuous administration of 7 d. After 1 h at 7 d to medicine, left incision in the middle of the neck of rats after anesthesia, we can firstly expose and isolate the left common carotid artery (CCA, and then expose external carotid artery (ECA and internal carotid artery (ICA. The common carotid artery and the external carotid artery are ligated. Then internal carotid artery with arterial clamp is temporarily clipped. Besides, cut the incision of 0.2 mm from 5 cm of the bifurcation of the common carotid artery. A thread Line bolt is inserted with more than 18–20 mm from bifurcation of CCA into the internal carotid artery until there is resistance. Then the entrance of the middle cerebral artery is blocked and internal carotid artery is ligated (the blank group only exposed the left blood vessel without Plugging wire. Finally it is gently pulled out the plug line after 2 h. Results: Compared with the model mice, Rabdosia rubescens total flavonoids can significantly relieve the injury of brain in hippocampus and cortex nerve cells; experimental rat focal cerebral ischemia was to improve again perfusion model of nerve function defect score mortality; significantly reduce brain homogenate NOS activity and no content, MDA, IL-1, TNF-a, ICAM-1 content; increase in brain homogenate SOD and ATPase activity (P < 0.05, P < 0.01; and reduce the serum S-100β protein content. Each dose group of the Rabdosia rubescens total flavonoids has a better Improvement effect on focal cerebral ischemia reperfusion model in rats.

  16. Aqueous extract of Rabdosia rubescens leaves: forming nanoparticles, targeting P-selectin, and inhibiting thrombosis.

    Science.gov (United States)

    Wang, Yuji; Tang, Jingcheng; Zhu, Haimei; Jiang, Xueyun; Liu, Jiawang; Xu, Wenyun; Ma, Haiping; Feng, Qiqi; Wu, Jianhui; Zhao, Ming; Peng, Shiqi

    2015-01-01

    The hot water extract of Rabdosia rubescens was traditionally used as an antithrombotic medicine. To explore its antithrombotic utility and mechanism, we carried out a series of in vitro and in vivo assays in this study. In vitro platelet aggregation assay showed that the half maximal inhibitory concentration values of aqueous extract of R. rubescens leaves (AERL) inhibiting platelet aggregation induced by thrombin, arachidonic acid, adenosine diphosphate, and platelet-activating factor ranged from 0.12 mg/mL to 1.43 mg/mL. The minimal effective oral dose of AERL inhibiting the rats from forming thrombus was 25 mg/kg. Both in vitro and in vivo actions were correlated with AERL concentration-dependently inhibiting sP-selectin release. In water, AERL formed nanoparticles, and their size depended on the concentration. Docking the five nucleotides, 21 phenolic acids, and four diterpenoids identified by high-performance liquid chromatography-photodiode array detector/(-)electrospray ionization-tandem mass spectrometry analysis into the active site of P-selectin, rosmarinic acid was predicted to be the antithrombotic ingredient of AERL. In flow cytometry analysis, 1 μM of rosmarinic acid effectively inhibited sP-selectin release in arachidonic acid-activated platelets. In a rat model, 5 mg/kg of oral rosmarinic acid effectively inhibited thrombosis.

  17. Aqueous extract of Rabdosia rubescens leaves: forming nanoparticles, targeting P-selectin, and inhibiting thrombosis

    Directory of Open Access Journals (Sweden)

    Wang Y

    2015-11-01

    Full Text Available Yuji Wang,1 Jingcheng Tang,1 Haimei Zhu,1 Xueyun Jiang,1 Jiawang Liu,1 Wenyun Xu,1 Haiping Ma,1 Qiqi Feng,1 Jianhui Wu,1 Ming Zhao,1,2 Shiqi Peng1 1Beijing Area Major Laboratory of Peptide and Small Molecular Drugs, Engineering Research Center of Endogenous Prophylactic of Ministry of Education of China, Beijing Laboratory of Biomedical Materials, College of Pharmaceutical Sciences, Capital Medical University, Beijing, People’s Republic of China; 2Faculty of Biomedical Science and Environmental Biology, Kaohsiung Medical University, Kaohsiung, Taiwan Abstract: The hot water extract of Rabdosia rubescens was traditionally used as an antithrombotic medicine. To explore its antithrombotic utility and mechanism, we carried out a series of in vitro and in vivo assays in this study. In vitro platelet aggregation assay showed that the half maximal inhibitory concentration values of aqueous extract of R. rubescens leaves (AERL inhibiting platelet aggregation induced by thrombin, arachidonic acid, adenosine diphosphate, and platelet-activating factor ranged from 0.12 mg/mL to 1.43 mg/mL. The minimal effective oral dose of AERL inhibiting the rats from forming thrombus was 25 mg/kg. Both in vitro and in vivo actions were correlated with AERL concentration-dependently inhibiting sP-selectin release. In water, AERL formed nanoparticles, and their size depended on the concentration. Docking the five nucleotides, 21 phenolic acids, and four diterpenoids identified by high-performance liquid chromatography–photodiode array detector/(-electrospray ionization-tandem mass spectrometry analysis into the active site of P-selectin, rosmarinic acid was predicted to be the antithrombotic ingredient of AERL. In flow cytometry analysis, 1 µM of rosmarinic acid effectively inhibited sP-selectin release in arachidonic acid-activated platelets. In a rat model, 5 mg/kg of oral rosmarinic acid effectively inhibited thrombosis. Keywords: R. rubescens, s

  18. Isolation and Purification of Oridonin from the Whole Plant of Isodon rubescens by High-Speed Counter-Current Chromatography

    Directory of Open Access Journals (Sweden)

    ChunYue Yu

    2011-09-01

    Full Text Available Semi-preparative high-speed counter-current chromatography (HSCCC was successfully used for isolation and purification of oridonin from Isodon rubescens by using a two-phase-solvent system composed of n-hexane-ethyl acetate-methanol-water (2.8:5:2.8:5, v/v/v/v. The targeted compound isolated, collected and purified by HSCCC was analyzed by high performance liquid chromatography (HPLC. A total of 40.6 mg of oridonin with the purity of 73.5% was obtained in less than 100 min from 100 mg of crude Isodon rubescens extract. The chemical structure of the compound was identified by IR, 1H-NMR and 13C-NMR.

  19. Cellular responses and bioremoval of nonylphenol by the bloom-forming cyanobacterium Planktothrix agardhii 1113

    Science.gov (United States)

    Medvedeva, Nadezda; Zaytseva, Tatyana; Kuzikova, Irina

    2017-07-01

    Nonylphenol (NP) is extensively used in agricultural, industrial and household applications. Moreover, NP is the major breakdown product of the nonionic surfactants, nonylphenol ethoxylates (NPEOs), the most widely used group of surfactants. Nonylphenol is persistent in the environment, highly toxic to aquatic organisms and is a potential endocrine disruptor. NP and NPEOs have been identified as priority hazardous substances under the Environmental Quality Standards Directive 2013/39/EU and are referred to in the list of substances of particular risk to the Baltic Sea. The toxicity of NP to the bloom-forming cyanobacterium Planktothrix agardhii 1113 isolated from the eastern Gulf of Finland, Baltic Sea and the bioremoval of NP by P. agardhii were studied. NP in concentrations > 0.4 mg L- 1 suppressed cyanobacterial growth. The median effective concentration of NP for P. agardhii after 4 days of treatment (EC50) was 1.5 mg L- 1. The removal of NP from the culture medium was primarily due to abiotic processes and biodegradation by the cyanobacterium rather than sorption by the cells. NP significantly increased the photosynthetic pigments, extracellular proteins and soluble exopolysaccharides content. The cyanobacterial growth inhibition was accompanied by the increased synthesis of microcystin dm-RR and of the odorous metabolites, geosmin and 2-methylisoborneol (MIB), by P. agardhii 1113. NP also notably increased the microcystin released into the environment. Increased levels of extracellular proteins, soluble exopolysaccharides, microcystins and odorous metabolites may affect the microbial loop in aquatic ecosystems. An increased level of malondialdehyde (MDA) was indicative of the formation of free radicals in P. agardhii under NP stress, whereas increased levels of superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH) and proline indicated the occurrence of a scavenging mechanism.

  20. Limnothrix redekei (Van Goor) Meffert (Cyanobacteria) strains from Lake Kastoria, Greece form a separate phylogenetic group.

    Science.gov (United States)

    Gkelis, S; Rajaniemi, P; Vardaka, E; Moustaka-Gouni, M; Lanaras, T; Sivonen, K

    2005-01-01

    Three strains of Limnothrix (Cyanobacteria) isolated from Lake Kastoria, Greece, were characterized based on their morphological features and 16S rRNA gene sequences. The Limnothrix isolates 007a, 165a, and 165c can morphologically be assigned to Limnothrix redekei (Van Goor) Meffert. The 16S rRNA gene of the Limnothrix strains showed a 99% similarity to the 16S rRNA gene of Planktothrix sp. FP1. Limnothrix redekei strains 165a, 165c, 007a and Planktothrix sp. FP1 formed a separate cluster in the cyanobacterial 16S rRNA gene tree. It was distinct from the Pseudanabaena cluster, which included the other Limnothrix strains isolated from northern temperate lakes. This is the first report on the phylogeny of L. redekei strains originating from a Mediterranean lake (southern Europe) and provides new data about the genus Limnothrix.

  1. [Effects of Pb2+ stress on seed germination & seedling growth of Rabdosia rubescens].

    Science.gov (United States)

    Kong, Si-Xin; Su, He; Zhan, Yan-Ting; Li, Hai-Kui; Cui, Xu-Sheng; Guo, Yu-Hai

    2014-11-01

    The seeds of Rabdosia rubescens were as the materials to research the impacts of different lead (Pb2+) concentrations(0, 135, 270, 540, 1 080 mg x L(-1)) on seed germination and seedling growth. The results show that: Low concentration of lead had no obvious effect on early germination of the seed, the germination vigor and germination speed were lightly higher but not significantly differed at the level of Pb concentration 135 mg x L(-1) with control group; Mid-high concentration of Pb solution (270-1 080 mg x L(-1)) significantly inhibited the seed germination and seedling growth, which reduced the seed germination rate, germination vigor, germination index, embryo root length and shoot length, growth index with increasing of Pb concentrations. There was a inhibitory effect on embryo shoot length and root length at mid-high lead concentrations stress, and stronger inhibitory effect on root , which was more sensitive than shoot to Pb stress(P germination rate and biomass fresh weight reducing 10%, is 195.18, 101.65 mg x L(-1).

  2. Genetic variability of microcystin biosynthesis genes in Planktothrix as elucidated from samples preserved by heat desiccation during three decades.

    Directory of Open Access Journals (Sweden)

    Veronika Ostermaier

    Full Text Available Historic samples of phytoplankton can provide information on the abundance of the toxigenic genotypes of cyanobacteria in dependence on increased or decreased eutrophication. The analysis of a time-series from preserved phytoplankton samples by quantitative PCR (qPCR extends observation periods considerably. The analysis of DNA from heat-desiccated samples by qPCR can be aggravated by point substitutions or the fragmentation of DNA introduced by the high temperature. In this study, we analyzed whether the heat desiccation of the cellular material of the cyanobacterium Planktothrix sp. introduced potential errors to the template DNA that is used for qPCR within (i 16S rDNA and phycocyanin genes and (ii the mcyA gene indicative of the incorporation of either dehydrobutyrine (Dhb or N-methyl-dehydroalanine (Mdha in position 7, and (ii the mcyB gene, which is indicative of homotyrosine (Hty in position 2 of the microcystin (MC molecule. Due to high temperature desiccation, the deterioration of the DNA template quality was rather due to fragmentation than due to nucleotide substitutions. By using the heat-desiccated samples of Lake Zürich, Switzerland the abundance of the Dhb, Mdha and Hty genotypes was determined during three decades (1977-2008. Despite major changes in the trophic state of the lake resulting in a major increase of the total Planktothrix population density, the proportion of these genotypes encoding the synthesis of different MC congeners showed high stability. Nevertheless, a decline of the most abundant mcyA genotype indicative of the synthesis of Dhb in position 7 of the MC molecule was observed. This decline could be related to the gradual incline in the proportion of a mutant genotype carrying a 1.8kbp deletion of this gene region. The increase of this mcyA (Dhb gene deletion mutant has been minor so far, however, and likely did not affect the overall toxicity of the population.

  3. Microfluidics and nanoparticles based amperometric biosensor for the detection of cyanobacteria (Planktothrix agardhii NIVA-CYA 116) DNA.

    Science.gov (United States)

    Ölcer, Zehra; Esen, Elif; Ersoy, Aylin; Budak, Sinan; Sever Kaya, Dilek; Yağmur Gök, Mehmet; Barut, Serkan; Üstek, Duran; Uludag, Yildiz

    2015-08-15

    Some of the cyanobacteria produce protease inhibitor oligopeptides such as cyanopeptolins and cause drinking water contamination; hence, their detection has great importance to monitor the well-being of water sources that is used for human consumption. In the current study, a fast and sensitive nucleic acid biosensor assay has been described where cyanopeptolin coding region of one of the cyanobacteria (Planktothrix agardhii NIVA-CYA 116) genome has been used as target for monitoring of the fresh water resources. A biochip that has two sets of Au electrode arrays, each consist of shared reference/counter electrodes and 3 working electrodes has been used for the assay. The biochip has been integrated to a microfluidics system and all steps of the assay have been performed during the reagent flow to achieve fast and sensitive DNA detection. On-line hybridization of the target on to the capture probe immobilized surface resulted in a very short assay duration with respect to the conventional static assays. The binding of the avidin and enzyme modified Au nanoparticles to the biotinylated detection probe and the subsequent injection of the substrate enabled a real-time amperometric measurement with a detection limit of 6×10(-12) M target DNA (calibration curve r(2)=0.98). The developed assay enables fast and sensitive detection of cyanopeptolin producing cyanobacteria from freshwater samples and hence shows a promising technology for toxic microorganism detection from environmental samples.

  4. Evaluación in vitro de compuestos presentes en Critoniella acuminata y Salvia rubescens frente a enzimas de desgranulación leucocitaria

    OpenAIRE

    Jaimes Galvis, Diana Carolina

    2010-01-01

    En el presente trabajo se implementaron técnicas in vitro con el fin de contribuir al estudio farmacológico de principios activos de plantas medicinales colombianas con potencial antiinflamatorio como: ayapina, aislada de Critoniella acuminata, amarisolide y arbutina aisladas de Salvia rubescens previamente en el Grupo de Investigación de Principios Bioactivos de Plantas. Se evaluaron enzimas relacionadas con el proceso de desgranulación leucocitaria: Mieloperoxidasa, Elastasa, Lisozima y Bet...

  5. Proposta de aproveitamento em resíduos de pau-rainha (Brosimum rubescens descartados pelo setor madeireiro Proposal of profite in residues of "pau-rainha" (Brosimum rubescens discarded for the lumber sector

    Directory of Open Access Journals (Sweden)

    Willian Hayasida

    2008-12-01

    Full Text Available A indústria da madeira do estado de Amazonas (Brasil contribui com a produção de uma quantidade grande de resíduos. Este trabalho visa indicar o uso final para espécie florestal pau-rainha (Brosimum rubescens Taubert, Moraceae. Os resíduos descartados durante o processamento mecânico da madeira foram utilizados na confecção de artefatos como: instrumentos musicais e artigos decorativos gerando resíduos menores (serragens. Foram obtidos extratos das serragens do cerne e alburno por maceração com hexano e metanol. O teor extrativo no cerne foi 19,87% e a porcentagem (com relação a serragem de xantiletina (2,2-dimetilcromeno cumarina obtida foi 2,35%. Não foi detectada a cumarina nos extratos do alburno. A xantiletina é reportada pelas atividades antiplaquetária, antifúngica e herbicida e alguns derivados possuem atividade em linhagens de células leucêmicas. A proposta de uso final adequado dos resíduos de pau-rainha para confecção de artefatos tem uma grande importância social e a busca de metabólitos secundários é bastante promissora pois estes podem ser transformados em novos produtos.Timber industry of Amazonas state (Brazil contribute with the production of great amount of residues. This paper aims to indicating end-uses for this forest species pau-rainha (Brosimum rubescens Taubert, Moraceae. The residues discharged during the mechanical processing in timber production were used as manufactured goods such as: musical instruments and decorative articles generating less wastes in sawmills. They were carried sawdust of the heartwood and sapwood and extraction by maceration with hexane and methanol. The heartwood extractive yield was 19.87% and content of xanthyletin (2,2-dimethylchromene coumarin was 2.35% with basis dry mass. It was not detected the coumarin in extracts of sapwood. Xanthyletin is reported as antiplatelet, antifungal and herbicide and some its derivatives have a leukaemic cells lineage activities. The

  6. Interactions between cyanobacteria and gastropods II. Impact of toxic Planktothrix agardhii on the life-history traits of Lymnaea stagnalis.

    Science.gov (United States)

    Lance, Emilie; Paty, Chrystelle; Bormans, Myriam; Brient, Luc; Gérard, Claudia

    2007-03-30

    Hepatotoxins are frequently produced by many cyanobacterial species. Microcystins (MCs) are the most frequent and widely studied hepatotoxins, with potentially hazardous repercussions on aquatic organisms. As a ubiquitous herbivore living in eutrophic freshwaters, the snail Lymnaea stagnalis (Gastropoda: Pulmonata) is particularly exposed to cyanobacteria. The toxic filamentous Planktothrix agardhii is common in temperate lakes and is therefore, a potential food resource for gastropods. In the first part of this study, we demonstrated the ingestion of toxic P. agardhii by L. stagnalis during a 5 weeks exposure, with concomitant accumulation of, on average, 60% of total MCs ingested. After 3 weeks of non-toxic food (lettuce), approximately 90% of MCs were eliminated from tissues. Here, we investigate the impact of toxic P. agardhii consumption on the life-history traits (survival, growth and fecundity), locomotion and the structure of digestive and genital glands of juvenile and adult L. stagnalis. We observed a decrease of growth regardless of age, although this was more marked in juveniles, and a reduction of fecundity in adults. Survival and locomotion were not affected. Reduction of growth and fecundity continued to be observed even after feeding of non-toxic food for 3 weeks. The structure of the digestive gland was altered during the intoxication period but not irreversibly as cells tended to recover a normal status after the 3-week detoxification period. No histopathological changes occurred in the genital gland and oocytes, and spermatozoids were present in the gonadic acini. The density of cyanobacterial suspensions used in this study was comparable to those regularly observed in lakes, particularly in eutrophic waters. These results are discussed in terms of the negative impact of toxic cyanobacteria on natural communities of freshwater gastropods, and potential cascading effects on the equilibrium and functioning of the ecosystem.

  7. Study on the Constituents of Rabdosia rubescens Hemsl%冬凌草化学成分的研究

    Institute of Scientific and Technical Information of China (English)

    尹锋; 梁敬钰; 刘净

    2003-01-01

    目的:从冬凌草Rabdosia rubescens Hemsl.的全草中提取分离活性成分.方法:采用硅胶柱层析,Sephadex LH-20凝胶柱层析进行分离,通过理化性质和波谱分析方法鉴定化合物结构.结果:从其石油醚及醋酸乙酯部分分离并鉴定了6个化合物,分别为胡萝卜苷(I)、β-谷甾醇(II)、冬凌草乙素(III)、冬凌草甲素(V)、Effusanin E (IV)和Aurantiamide acetate(VI).结论:化合物IV为首次从该植物中分得,化合物VI为首次从该属植物中分得.本文还首次对化合物IV的1HNMR和13CNMR作了较全面的归属.

  8. Chemical Constituents of Rabdosia rubescens(Hemsl.)Hara%冬凌草的化学成分研究

    Institute of Scientific and Technical Information of China (English)

    卢海英; 王孟华; 张雪芹; 吴斐华; 梁敬钰

    2013-01-01

    目的 研究冬凌草的化学成分.方法 应用色谱层析、萃取、重结晶等方法对河南济源产冬凌草(Rabdosia rubescens(Hemsl.)Hara)的化学成份进行研究,应用波谱解析和理化方法对化合物进行结构鉴定.结果 从冬凌草中分离得到11个化合物,分别鉴定为:牛尾草甲素(Rabdoternin A,1)、牛尾草丙素(Rabdoternin C,2)、lasiokaurin(3)、enmenol(4)、牛尾草乙素(RabdoterninB,5)、木栓酮(Friedelin,6)、乌苏酸(Ursolic acid,7)、5,8,4-三羟基-6,7,3-三甲氧基黄酮(5,8,4-tri-hydroxyl-6,7,3-tri-methoxyl-flavone,8)、苜蓿素(Tricin,9)、线蓟素(Cirsiliol,10)、胡麻素(Pedalitin,11).

  9. Research of Seed Quality Grading of Rabdosia Rubescens%冬凌草种子质量分级标准的研究

    Institute of Scientific and Technical Information of China (English)

    李晓婷; 董诚明; 谢小龙

    2013-01-01

    Objective:To formulate the seed quality grading standard of Rabdosia rubescens. Methods;The purity,thousand kernels quality, germination percentage, germinative energy, moisture content, viability, and of Rabdosia rubescens seed samples from 40 regions were tested. Through software of SPSS 17. O,the key indicator for seed quality grading were defined and formulate the seed quality grading standard of Rabdosia rubescens. Result; All the seeds of Rabdosia rubescens were sorted into three grades. The seed quality of each grade should reach the following requirements:for first grade seeds,germination percentage ≥89% .germinative energy ≥81% ,thousand kernels weight ≥0.56 g;for second grade seeds,germination percentage 78% -89% .germinative energy 70% -81% .thousand kernels weight 0.53 -0. 56 g;for third grade seeds, germination percentage 71% -78% .germinative energy 57% - 70% .thousand kernels weight 0. 52 -0. 53 g. Conclusion; Germination percentage was the primary indicator of seed quality grading, germinative energy and thousand-grain quality were important reference indicators. Reference citation: Li Xiaoting, Dong Chengming, Xie Xiaolong. Research of Seed Quality Grading of Rabdosia Rubescens [ J ]. China Journal of Chinese Medicine.2013,28(5) :697 -699. Objective:To formulate the seed quality grading standard of Rabdosia rubescens. Methods;The purity,thousand kernels quality, germination percentage, germinative energy, moisture content, viability, and of Rabdosia rubescens seed samples from 40 regions were tested. Through software of SPSS 17. O,the key indicator for seed quality grading were defined and formulate the seed quality grading standard of Rabdosia rubescens. Result; All the seeds of Rabdosia rubescens were sorted into three grades. The seed quality of each grade should reach the following requirements:for first grade seeds,germination percentage ≥89% .germinative energy ≥81% ,thousand kernels weight ≥0.56 g;for second grade seeds

  10. 冬凌草中的一个新生物碱%A New Alkaloid from the Aerial Part of Rabdosia rubescens

    Institute of Scientific and Technical Information of China (English)

    冯卫生; 李钦; 郑晓珂; 匡海学

    2007-01-01

    目的:研究冬凌草(Rabdosia rubescens (Hemls.) Hara)地上部分的化学成分.方法:利用大孔吸附树脂色谱进行分离纯化,根据化合物的理化性质和光谱数据鉴定结构.结果:从冬凌草地上部分分离得到7个化合物,分别为:冬凌草碱(1),黄嘌呤(2),芹菜素-6,8-二-C-β-D-葡萄糖苷(3), 7-羟基-4(1H)-喹啉酮(4),1,5-二-(3,4-二羟基苯基)-乙烯醚(5),3-(3,4-二羟基苯基)-2-异丙氧基-丙酸(6),邻苯二甲酸双-(2-乙基己基)酯(7).结论:化合物1为新化合物,其余化合物均为首次从该属植物中分离得到.%AIM: To study the chemical constituents of the aerial part of Rabdosia rubescens (Hemls.) Hara. METHODS: Fresh sample of the aerial part of Rabdosia rubescens was extracted with 70% Me2CO, discolored by activated charcoal. The concentrated material was partitioned with ether, ethyl acetate, and n-butanol. The fraction of n-BuOH extract was chromatographed over Diaion HP-20 and Toyopearl HW-40 column chromatography. The compounds were identified on the basis of their physiochemical and spectral data. RESULTS: Seven compounds, including a new alkaloid which was named donglingine (1) , were isolated from the aerial part of Rabdosia rubescens. The structure of compound 1 was elucidated as 3R-4-(N-(3, 7-dihydroxy-2-oxo-1, 2, 3, 4-tetrahydro-quinolin-6-yl)-acetamido)-butanamide. The other six known compounds were identified as xanthine (2), apigenin-6, 8-di-C-β-D-glucopyranoside (3), 7-hydroxy-4(1H)-quinolinone (4), trans-1, 5-di-(3, 4-dihydroxyphenyl)-divinyl ether (5), 3-(3, 4-dihydroxyphenyl)-2-isopropoxy-propionic acid (6), bis-(2-ethylhexyl)-phthalate (7). CONCLUSIONS: Compound 1 is a new compound and the other six known compounds were isolated from this genus for the first time.

  11. Review on chemistry and pharmacology of Rabdosia rubescens%冬凌草的化学和药理作用研究

    Institute of Scientific and Technical Information of China (English)

    高世勇; 王珑

    2014-01-01

    To introduce the results of researching the chemical composition , pharmacological effects, anti-tumor mechanisms and clinical application of Rabdosia rubescens , this paper summarized the research on Rabdosia rubescens at home and abroad systematically by a lot of literature .It showed that Rabdosia rubescens contained some chemical compositions , inclu-ding terpenoids, alkaloids, steroids, flavonoids, volatile oils, amino acids, organic acids, monosaccharides , and has some pharmacological effects , such as anti-tumor, anti-inflamma-tory, immune-enhancing, anti-oxidation,anti-mutation and anti-hypertension.The anti-tumor mechanisms are shown as follows: repression of cell cycle , decrease of telomerase activity , inhibition of cell membrane sodium pump activity , inducing tumor cell apoptosis and reversal of multidrug resistance .In clinical , it has effect on esophageal cancer , gastric cardia canc-er, liver cancer , breast cancer and other cancers . This paper showed that Rabdosia rubescens has extensive pharmacological effects and good anticancer activity .%介绍冬凌草的化学成分、药理作用、抗肿瘤机制、临床应用等方面的研究成果。通过文献系统地介绍了国内外目前关于冬凌草的研究。研究发现冬凌草中含有萜类、生物碱、甾体、黄酮、挥发油、氨基酸、有机酸、单糖等化学成分,并具有抗肿瘤、抗菌消炎、免疫增强、抗氧化、抗突变、降压等药理作用,而其抗肿瘤机制包括阻遏细胞周期、下调端粒酶活性、抑制细胞膜钠泵活性、诱导肿瘤细胞凋亡、逆转多药耐药等,在临床上对食管癌、贲门癌、肝癌、乳腺癌等多种癌症均具有疗效。表明冬凌草具有广泛的药理作用和良好的抗癌活性。

  12. RUBESCENSIN H,A NEW DITERPENOID EXTRACTED FROM ISODON RUBESCENS%冬凌草中一新的二萜成分--冬凌草辛素

    Institute of Scientific and Technical Information of China (English)

    刘延泽; 侯建军; 吴养洁

    2000-01-01

    从河南省鹤壁地区产冬凌草[Isodon rubescens(Hemsl.)Hara]叶中分得一个新的二萜化合物,命名为冬凌草辛素(Rubescensin H),经NMR谱等确定其结构为6β,7β,14β,15R-四羟基-11β-甲酰氧基-7α,20-环氧-对映-贝壳杉-16-烯.

  13. Research progress of pharmacological actions and clinical application of rabdosia rubescens%冬凌草的药理作用与临床应用

    Institute of Scientific and Technical Information of China (English)

    戴华; 刘四海; 周霞; 魏冬云

    2008-01-01

    冬凌草,又名冰凌草(Rabdosia rubescens (Hamst)),系唇形科香茶菜属植物,味甘苦,性微寒。全草为民间常用草药,具有清热解毒、消炎止痛、健胃活血等功效。化学成份分析证实,冬凌草含有从单萜、倍半萜、二萜、三萜、挥发油、甙类及多糖等一系列物质[1]。从冬凌草叶的提取物中分离出五种二萜类化合物,即冬凌草甲、乙、丙、丁及戊素,为其主要抗癌活性成份。

  14. Research and Evaluation on Chemical Fingerprints of Diterpenoids from Rabdosia rubescens%冬凌草二萜类成分的化学指纹图谱研究及评价

    Institute of Scientific and Technical Information of China (English)

    陈随清; 宋君; 崔璨

    2012-01-01

    为了建立冬凌草(Rabdosia rubescens)二萜类成分的HPLC指纹图谱,并通过指纹图谱对来自不同产地和不同类型的冬凌草进行评价,本研究以10批太行山产冬凌草HPLC色谱图为参照,建立了冬凌草二萜类成分的指纹图谱,色谱条件为,色谱柱:phenomsil C18(250 ×4.6 mm,5 μm)柱;流动相:甲醇:0.5%磷酸水溶液梯度洗脱;柱温:30℃;检测波长:238 nm;流速:0.8 mL/min.通过化学成分指纹图谱相似度分析以及主成分分析方法,综合评价不同产地冬凌草样品质量的差异.结果表明冬凌草种质资源出现多种分化,不同地区冬凌草二萜类成分差异明显;不同变异类型冬凌草二萜类成分也发生了变化,但没有明显规律性.%In this paper, chemical fingerprints were established by referring to the HPLC chromatography of ten batch samples from the Taihang Mountains. Phenomsil C18 (250 × 4. 6 mm,5 μm) columns were used and methanol-water (0. 5% phosphoric acid.) was chosen as the mobile phase. The column temperature was 30℃ and the fingerprints were detected at 238 nm. The flow rate was 0. 8 mL/min. The quality of Rabdosia rubescens herba from different places was evaluated by similarity analysis and principal component analysis of chemical fingerprints. The results showed that R. rubescens had multiple germplasm,the diterpenoids from R. rubescens in different areas had significant differences,and the diterpenoids of different mutation types were changed,but showed no obvious trend.The results of this article provide a scientific basis for the protection and development of R. rubescens germplasm.

  15. Stability of toxin gene proportion in red-pigmented populations of the cyanobacterium Planktothrix during 29 years of re-oligotrophication of Lake Zürich

    Directory of Open Access Journals (Sweden)

    Ostermaier Veronika

    2012-12-01

    Full Text Available Abstract Background Harmful algal blooms deteriorate the services of aquatic ecosystems. They are often formed by cyanobacteria composed of genotypes able to produce a certain toxin, for example, the hepatotoxin microcystin (MC, but also of nontoxic genotypes that either carry mutations in the genes encoding toxin synthesis or that lost those genes during evolution. In general, cyanobacterial blooms are favored by eutrophication. Very little is known about the stability of the toxic/nontoxic genotype composition during trophic change. Results Archived samples of preserved phytoplankton on filters from aquatic ecosystems that underwent changes in the trophic state provide a so far unrealized possibility to analyze the response of toxic/nontoxic genotype composition to the environment. During a period of 29 years of re-oligotrophication of the deep, physically stratified Lake Zürich (1980 to 2008, the population of the stratifying cyanobacterium Planktothrix was at a minimum during the most eutrophic years (1980 to 1984, but increased and dominated the phytoplankton during the past two decades. Quantitative polymerase chain reaction revealed that during the whole observation period the proportion of the toxic genotype was strikingly stable, that is, close to 100%. Inactive MC genotypes carrying mutations within the MC synthesis genes never became abundant. Unexpectedly, a nontoxic genotype, which lost its MC genes during evolution, and which could be shown to be dominant under eutrophic conditions in shallow polymictic lakes, also co-occurred in Lake Zürich but was never abundant. As it is most likely that this nontoxic genotype contains relatively weak gas vesicles unable to withstand the high water pressure in deep lakes, it is concluded that regular deep mixing selectively reduced its abundance through the destruction of gas vesicles. Conclusions The stability in toxic genotype dominance gives evidence for the adaptation to deep mixing of a

  16. Extraction and Composition Analysis of the Polysaccharide in Rabdosia rubescens%冬凌草多糖的提取、分离及理化性质研究

    Institute of Scientific and Technical Information of China (English)

    侯飞; 刘克为; 梁惠; 高华

    2011-01-01

    为研究冬凌草多糖的理化性质和质量,对冬凌草采用热水、稀碱提取,乙醇沉淀,等电点法脱蛋白后得到冬凌草粗多糖,经Q Sepharose 4 Fast Flow离子交换层析柱和Sephacryl S-100凝胶柱进一步纯化后得到4个纯度较高的组分STPS-Ⅰ、STPS-Ⅱ、JTPS-Ⅰ、JTPS-Ⅱ.对各组分的总糖含量、糖醛酸含量、硫酸根含量以及蛋白含量进行了测定,利用高效液相色谱法测定了单糖组成和分子量.结果 显示冬凌草多糖不同组分的分子量相近,化学组成及单糖组成明显不同.%To study the physical and chemical properties and quality of polysaccharides in Rabdosia rubescens. Crude polysaccharides of Rabdosia rubescens were obtained by extraction in hot water and dilute alkali successively, precipitation with ethanol and removal of protein by method of isoelectric point. STPS- Ⅰ, STPS- Ⅱ,JTPS- Ⅰ, JTPS-Ⅱ were isolated by a combination of ion exchange chromatography on Q Sepharose 4 Fast Flow and gel permeation over Sephacryl S-100 and with high purity. Their chemical characteristics including the content of total sugar, uronic acid, sulfate and protein as well as monosaccharide composition and molecular weight were investigated. The results showed that the molecular weight of different components of polysaccharides in Rabdosia rubescens was similar, while chemical composition and monosaccharide composition obvious different.

  17. [Jaridonin, a new diterpenoid from Isodon rubescens, induces cell cycle arrest in gastric cancer cells through activating ataxia telangiectasia mutated kinase].

    Science.gov (United States)

    Ma, Y C; Su, N; Zhao, N M; Li, Q Y; Zhang, M; Zhao, H W; Liu, H M; Qin, Y H

    2016-04-01

    To study the effects of Jaridonin, a novel diterpenoid from isodon rubescens, on the cell cycle of human gastric cancer cells and its molecular mechanism of action. Flow cytometry was used to analyze the cell cycle distribution and expression of ataxia telangiectasia mutated kinase (ATM) after Jaridonin treatment. Western blot was performed to detect the expression of cell cycle-related proteins. The results of flow cytometry showed that the percentages of MGC-803 cells in G(2)/M phase at 6 hours after 0, 10, 20 μmol/L Jaridonin-treatment were (10.8±2.2)%, (18.2±2.5)%, (27.3±3.2)%, respectively; those at 12 hours after Jaridonin-treatment were (12.0±1.5)%, (24.1±2.0)% and (39.7±5.2)%, respectively, indicating a G2/M phase arrest of MGC-803 cells was resulted in a time- and dose-dependent manner. The expressions of ATM, Chk1, Chk2, phosphorylated Cdc2 and CDK2 were up-regulated in the MGC-803 cells after Jaridonin treatment, while the levels of Cdc2 and CDK2 were decreased. KU-55933, an inhibitor of ATM, reversed the expression of relevant proteins and G(2)/M phase arrest induced by Jaridonin. Jaridonin can significantly induce G(2)/M arrest in gastric cancer MGC-803 cells. Its mechanism may be related to the activation of ATM and Chk1/2, and inactivation of Cdc2 and CDK2 phosphorylation.

  18. 冬凌草保健饮料的生产工艺研究%Production technology of Rabdosia rubescens health drink

    Institute of Scientific and Technical Information of China (English)

    鲁国荣

    2011-01-01

    Comparative analysis, mathematical statistics and orthogonal test method were adopted to optimize the production technology of the health drink including the ratio, extraction temperature and blending process. The optimal formulation was determined by orthogonal test as follows: the amount of Rabdosia rubescens juice 4%, malic acid 0.1%, citric acid 0.1%, pectin 0.15% and CMC-Na 0.18%. Under these conditions, the product had good nutrition and unique flavor, and it was stable and has no layer and precipitation. The ratio of sugar and acid was suitable. The shelf life of the product was up to 6 months.%采用对比分析、数理统计和正交试验等方法,对配比、浸提温度和调配等工艺进行了研究,获得了制作冬凌草保健饮料的最佳工艺及配方:冬凌草鲜汁用量4%,苹果酸0.10%,柠檬酸0.10%,果胶0.15%和CMC-Na 0.18%,可获得营养丰富、风味独特,具有良好的悬浮稳定性和流动性,不分层、无沉淀、糖酸比合理产品,保质期可达6个月以上.

  19. 冬凌草水提物治疗慢性咽炎的临床疗效及其安全性初步研究%Therapeutic effect of rabdosia rubescens aqueous extract on chronic pharyngitis and its safty

    Institute of Scientific and Technical Information of China (English)

    马征; 胡春生; 张莹莹

    2011-01-01

    Objective To evaluate the clinical therapeutic effect of rabdosia rubescens aqueous extract on chronic pharyngitis and its safty. Methods One hundred and two patients suffered from chronic pharyngtis were randomly divided into an interventional group (n =51 ) and a placebo group ( n = 51 ). These volunteers were given 220 mL test materials once a day double-blindly for 30 days. All patients took routine physical examinations, and their throat symptom and pharynx signs were observed before and after the experiment. Results After the patients had consumed rabdosia rubescens aqueous extract and the placebo for 30 days, the improvement rates of main clinical symptom and signs in the interventional group were 67.31% and 61.54%, while those in placebo group were 19.23% and 11.54%, with significant difference (P <0.05). Before the experiment,the integral of main clinical symptom and signs between the two groups did not show significant difference (P > 0.05 ). But after 30 days, the integral of main clinical symptom and signs in the interventional group significantly decreased ( P < 0.05 ), compared with itself before the experiment and the placebo group. Conclusion Rabdosia rubescens aqueous extract is safe and effective for patients with chronic pharyngitis.%目的:评价冬凌草水提物治疗慢性咽炎的临床疗效及其安全性.方法:将102例慢性咽炎患者随机分为干预组(n=51)和安慰剂组(n=51),采用双盲法给予受试物,每日1次,每次220 mL,30 d为1个疗程.试验前后分别进行常规体检,观察咽部临床症状,检查咽部体征.结果:患者饮用冬凌草水提物和安慰剂30 d后,干预组主要临床症状、体征改善率分别为67.31%和61.54%,安慰剂组主要临床症状、体征改善率分别为19.23%和11.54%,两者差异有统计学意义(P0.05),30 d后干预组主要临床症状积分、体征积分降低,与自身试验前及安慰剂组比较,差异有统计学意义(P<0.05).结论:冬凌草水

  20. Determination of Oridonin Content in Rabdosia Rubescens Syrup by HPLC%高效液相色谱法测定冬凌草糖浆中冬凌草甲素含量

    Institute of Scientific and Technical Information of China (English)

    蔡俊安

    2011-01-01

    Objective To establish the method for determining the oridonin content in Rabdosia Rubescens Syrup by HPLC. Methods To use Diamonsil C18 column(250 mm ×4.6 mm, 5 μm)with methanol-water(50:50) as the mobile phase. The detection wavelength was 239 nm and the flow rate was 1.0 mL/min. Results The calibration curve was linear during the range of 0. 093- 0. 746 μg for the oridonin and the linear equation was Y=413 933.35-63428.66X, r=0.9997(n=5).The average recovery rate was 99.0%, RSD=1.06%(n=5). Conclusion This method is simple and accurate with good specificity and reproducibility, which provides the scientific and effective method for quantitative analysis of Rabdosia Rubescens Syrup.%目的 建立测定冬凌草糖浆的冬凌草甲素含量的高效液相色谱法.方法采用Diamonsil C18色谱柱(250mm×4.6mm,5μm),以甲醇-水(50:50)为流动相,流速为1.0 mL/min,检测波长为239 nm.结果冬凌草甲素进样量在0.093~0.746μg范围内与峰面积积分值线性关系良好,回归方程为Y=413 933.35-63 428.66X,r=0.999 7(n=5);平均加样回收率为99.0%,RSD为1.06%(n=5).结论该法简便、准确、专属性和重复性好,为冬凌草糖浆中冬凌草甲素的定量分析提供了科学有效的方法.

  1. CARACTERIZAÇÃO COLORIMÉTRICA DAS MADEIRAS DE MUIRAPIRANGA (Brosimum rubescensTaub. E DE SERINGUEIRA (Hevea brasiliensis, clone Tjir 16 Müll Arg. VISANDO À UTILIZAÇÃO EM INTERIORES

    Directory of Open Access Journals (Sweden)

    Cristine da Silva Autran

    2006-09-01

    Full Text Available Ainda que recente, a técnica para a determinação da cor da madeira por meio da colorimetria quantitativa mostra-se precisa e eficaz. O sistema CIELAB 1976, que determina os parâmetros colorimétricos L*, a*, b*, C e h*, mostrou-se eficiente para a determinação da cor das madeiras de muirapiranga (Brosimum rubescens e de seringueira (Hevea brasiliensis, clone Tjir 16. A madeira de muirapiranga é de cor vermelha-amarronzada (L* de 42,39, tendo o pigmento vermelho (a* de 22,02 como determinante, apesar de o pigmento amarelo (b* ter influência significativa na definição de sua cor. A madeira de seringueira apresenta cor amarela (L* de 77,55, fortemente influenciada pelo pigmento amarelo (b* de 19,61. Considerando o parâmetro cor, ambas as madeiras apresentam potenciais para serem utilizadas em interiores.

  2. Estudo da variabilidade da retenção do preservante CCA tipo A na madeira de Brosimum rubescens Taub. Moraceae - (pau-rainha uma espécie madeireira da região Amazônica

    Directory of Open Access Journals (Sweden)

    Sales-Campos Ceci

    2003-01-01

    Full Text Available Avaliou-se a variabilidade da tratabilidade da espécie madeireira Brosimum rubescens Taub. Moraceae (pau-rainha, abordando três diferentes alturas do tronco (base, meio e ápice e duas partes (cerne e alburno. O processo utilizado foi o de impregnação sob pressão, através do método de célula-cheia ou Bethell, e o preservante foi o CCA, tipo A, a 2% de concentração. A análise da variabilidade deu-se em função da retenção. Ao comparar os dados de retenção (kg/m³ das diferentes alturas e partes do tronco, constatou-se que o grau de tratabilidade do alburno é moderadamente difícil, enquanto o cerne é refratário. Os resultados de retenção das toras estudadas nas diferentes alturas da árvore não apresentaram diferença significativa, entretanto existe diferença significativa de retenção entre as partes (cerne e alburno. A análise de microdistribuição do preservante através do estudo anatômico funciona como ferramenta auxiliar na interpretação desses resultados.

  3. Effects of rare-earth elements La3+and Ce3+ on the growth of Rabdosia rubescens regeneration plant and the accumulation of main secondary metabolites%稀土元素镧和铈对冬凌草再生植株生长及次生代谢产物的影响

    Institute of Scientific and Technical Information of China (English)

    董诚明; 曹利华; 苏秀红; 张艳贞; 乔毅琳; 姚锋

    2015-01-01

    以冬凌草无菌苗为材料,在冬凌草再生植株时期,添加不同浓度的稀土元素镧和铈,用重量法测定其单株平均鲜重及干重,用高效液相法测定冬凌草甲素、乙素、迷迭香酸的含量,参考农作物、园艺作物种质评比的方法,根据冬凌草生产中各项指标的重要性,设置权重,计算加权后得到综合评分对其进行综合评价,探讨稀土元素镧、铈对冬凌草再生植株产量及次生代谢产物冬凌草甲素、乙素、迷迭香酸含量的影响.结果表明:空白对照组综合评分为62.99分,添加稀土元素铈的条件下,1μmol·L-1 CeCl3·7 H 2 O 评分最高为87.96分,添加稀土元素镧的条件下,5μmol·L-1 LaCl3·6 H 2 O 评分最高为74.44分,这表明 CeCl3·7 H 2 O 对冬凌草再生植株生长及次生代谢产物积累的促进作用优于 LaCl3·6 H 2 O;适宜浓度的镧、铈能促进冬凌草再生植株的生长及次生代谢产物冬凌草甲素、冬凌草乙素、迷迭香酸的合成,而高浓度10μmol·L-1 LaCl3·6 H 2 O 具有抑制的情况.该研究结果将对进一步研究稀土元素对冬凌草再生植株生长的促进作用机制奠定基础,为植物组织培养中如何科学合理地使用稀土元素提供理论依据.%Aseptic seedlings of Rabdosia rubescens were used as the experiment material.In R .rubescens regeneration period,the rare-earth elements La3+ or Ce3+ with different concentrations were added in the culture medium.Fresh and dry weight of the plant were determined by gravimetric method.HPLC method was used for the determination of oridonin,ponicidin and rosmarinic acid content.We determined weight according to evaluating methods of agricultural and horticultural crops and the importance of indexes in the production of R .rubescens .The quality synthetic evalua-tion was also carried out according to weighted mark.The effects of rare earth elements La3+ and Ce3+ on R .rubescens tissue culture and the contents of

  4. 不同分离提纯工艺对冬凌草多糖提取率与免疫活性的影响%Effect of Separation and Purification Processes on Extraction Ratio of Polysaccharides in Rabdosia rubescens and Immunocompetence

    Institute of Scientific and Technical Information of China (English)

    刘芳; 刘培毅; 郝兰芳; 周晶

    2011-01-01

    Objective:To select a good method for purifying polysaccharides from Rabdosia rubescens ,and study their immunological activity. Methods:DEAE-Sepharose Fast Flow(Cl- )weak polar anion-exchange chromatography and stepwise ethanol precipitation were used to isolate and purify the polysaccharides from Rabdosia rubescens, respectively. MTT method was used to evaluate the immune activity. Results: Five components were obtained from DEAE-Sepharose Fast Flow ( Cl - ) weak polar anion-exchange chromatography and four polysaccharides were obtained through alcohol precipitation. Conclusion:Polysaccharides from Rabdosia rubescens by stepwise ethanol precipitation show stronger immunological activity. Their immunomodulatory effect and related mechanism will be researched further.%目的:优选分离冬凌草多糖的方法,探究不同分离方法对冬凌草多糖分离效果的影响.方法:分别以DEAE-Sepharose Fast Flow(CI-型)弱极性阴离子交换层析法、乙醇分级醇析法对冬凌草粗多糖进行分离纯化,以不同分离组分中多糖含量及其免疫活性比较优选冬凌草粗多糖的分离工艺.结果:DEAE-Sepharose Fast Flow(Cl型)弱极性阴离子交换层析法分离得到5个组分,通过乙醇分级醇沉初步得到4个冬凌草多糖组分,前者分离产品纯度较高,而后者产品在体外小鼠脾淋巴T细胞的增殖实验中表现出较强生物活性.结论:为进一步研究冬凌草多糖的生物活性,可选用乙醇分级醇沉法对冬凌草多糖进行分离纯化.

  5. Effect of Rare-earth Elements on Callus Growth and Oridonin and Ponicidin in Rabdosia rubescens%稀土元素对冬凌草愈伤组织生长及冬凌草甲素、乙素含量的影响

    Institute of Scientific and Technical Information of China (English)

    张艳贞; 董诚明; 苏秀红; 曹利华

    2013-01-01

    目的:探讨稀土元素镧、铈对冬凌草愈伤组织生长及冬凌草甲素、乙素含量的影响.方法:冬凌草均匀愈伤组织在添加不同浓度La3或Ce3的培养基中培养,通过质量法测定愈伤组织鲜质量、绘制生长曲线,HPLC测定甲素、乙素含量.结果:CeCl3·7H2O浓度为1μmol·L-1时,愈伤生物量最高,是空白条件下的2.4倍.空白及对照条件下甲素含量均为0;空白条件下乙素含量最低为0.11%,随着Ce3+浓度升高而升高,当浓度为10 μmol· L-1时高达0.58%;乙素随着La3+浓度升高而降低,当浓度为0.1 μmol· L-1时含量高达0.44%.结论:0~ 10 μmol·L-1的La3+及Ce3+均有利于冬凌草愈伤生物量的积累及乙素的合成,对甲素的合成无影响,将CeCl3 ·7H2O浓度10 μmol· L-1作为最佳条件选择.%Objective: To study the effect of rare-earth elements La3 + and Ce3+ on callus growth and oridonin and ponicidin in Rabdosia rubescens. Method: The uniform callus of R. rubescens was cultivated in different concentration of La or Ce in culture medium, and the gravimetric method was used for the determination of callus fresh weight and cell growth curve; HPLC method was used for the determination of oridonin and ponicidin content. Result: The supreme biomass of callus was 2.4 times of blank conditions when CeCl3· 7H2O concentration was 1 μmol ·L-1. Blank and the control conditions of oridonin content were 0; ponicidin was the lowest with 0. 11% at blank condition; the ponicidin concentration increased as Ce3+ncreasing, it was up to 0. 58% when Ce3+ concentration was 10 (μmol ·L-1 while the ponicidin concentration decreased as La3 + increasing, the content was 0. 44% when La3 + concentration was 0. 1 μmol ·L-1. Conclusion: 0-10 μmol ·L-1 La3+ and Ce3 + promoted R. rubescens callus biomass accumulation and ponicidin synthesis, didn't promote the synthesis of oridonin, the CeCl3 ·7H2O concentration of 10 μmol ·L-1 was the selection of optimum

  6. Study on Cryopreservation and Plant Regeneration of in Vitro Shoot-tips of Rabdosia Rubescens (Hemsl.) Hara. by Vitrification%冬凌草试管苗茎尖玻璃化法超低温保存及植株再生研究

    Institute of Scientific and Technical Information of China (English)

    卢利平; 艾鹏飞

    2007-01-01

    对冬凌草[Rabdosia rubescens (Hemsl.)Hara.]试管苗茎尖进行了玻璃化法超低温保存及植株再生研究.结果表明:1~2 cm嫩梢在培养基MS+0.5 mol/L蔗糖上培养3 d,切取2~3 mm茎尖,室温(20℃)下装载液(60%PVS2)过渡30 min,0℃下玻璃化液(PVS2)处理45 min,投入液氮保存1 d后,40℃水浴化冻,1.2 mol/L蔗糖的MS培养基洗涤20 min,接种于6-BA 0.8 mg/L、IAA 0.05 mg/L的MS培养基上,暗处理1周后转到正常光下,成活率达到86%,再生植株生长和分化正常.

  7. Hip flexor strain - aftercare

    Science.gov (United States)

    ... flexor - aftercare; Hip flexor injury - aftercare; Hip flexor tear - aftercare; Iliopsoas strain - aftercare; Strained iliopsoas muscle - aftercare; Torn iliopsoas muscle - aftercare; Psoas strain - aftercare

  8. Grazing on microcystin-producing and microcystin-free phytoplankters by different filter-feeders: implications for lake restoration

    NARCIS (Netherlands)

    Dionisio Pires, L.M.; Bontes, B.M.; Samchyshyna, L.; Jong, J.P.; Van Donk, E.; Ibelings, B.W.

    2007-01-01

    We studied grazing on the green alga Scenedesmus obliquus and the cyanobacterium Planktothrix agardhii (a microcystin-producing and a microcystin- free strain) by three different filter-feeders to compare the efficiency with which these grazers remove Planktothrix from the water. The filterfeeders w

  9. Geobacteraceae strains and methods

    Science.gov (United States)

    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.

  10. Sprains and Strains

    Science.gov (United States)

    ... wrestling put people at risk for strains. Gymnastics, tennis, rowing, golf, and other sports that require extensive gripping can increase the risk of hand and forearm strains. Elbow strains sometimes occur in people who participate in ...

  11. Muscle strain treatment

    Science.gov (United States)

    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 ( ...

  12. Muscle strain (image)

    Science.gov (United States)

    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 ...

  13. Antitumor Activity of Components from Isondon rubescens (Hemsley) H. Hara and Their Acetyl Derivatives Predicted by Michael Addition Reaction%迈克尔加成反应预测冬凌草活性成分及其乙酰化产物抗肿瘤活性

    Institute of Scientific and Technical Information of China (English)

    刘建群; 高俊博

    2016-01-01

    为了快速、简便地评价冬凌草(Isodon rubescens(Hemsley) H. Hara)活性成分的抗肿瘤活性,以冬凌草活性成分冬凌草甲素和冬凌草乙素及其乙酰化产物与对硝基苯甲酰乙酸乙酯( ENBA)进行迈克尔加成反应,以反应动力学得出迈克尔加成反应的反应活性,首次以反应活性预测了对冬凌草甲素(1)、冬凌草乙素(2)、1,14-二乙酰基冬凌草甲素(1a)和1,6-二乙酰基冬凌草乙素(2a)4个对映-贝壳杉烯的抗肿瘤活性。结果表明:4种活性成分的迈克尔加成反应均符合二级动力学方程,反应活性1>1a>2>2a,根据阿伦尼乌斯公式,测得冬凌草甲素活化能(Ea)为(38.7±5.8) kJ/mol,冬凌草乙素Ea 为(46.8±7.1) kJ/mol。采用1 H NMR和13 C NMR等波谱技术鉴定冬凌草甲素与ENBA经迈克尔加成反应得到的新化合物为1α,6β,7β,14β-四羟基-7α,20-环氧-17-(2-(3-(4-硝基苯基))-3-氧-丙酸乙酯)-对映贝壳杉烷-15-酮,命名为nitrobenoridonin (1b)。4个对映-贝壳杉烯具有较强的体外抗肿瘤活性,经测定它们的抗肿瘤活性大小依次为1>1a>2>2a,与其迈克尔加成反应活性排序一致,表明迈克尔加成反应活性与抗肿瘤活性之间存在较好的相关性,可以通过测定迈克尔加成反应活性预测对映-贝壳杉烯的抗肿瘤活性。%The kinetics of the Michael addition reaction among four ent-kaurenes, i. e. oridonin ( 1 ) and ponicidin (2) from Isodon rubescens (Hemsley) H. Hara,1,14-diacetyl oridonin (1a),1,6-diacetyl ponicidin (2a) and ethyl 4-nitrobenzoylacetate ( ENBA) was investigated for the first time in order to conveniently predict their antitumor activity. Stoichiometric analysis indicated that the reaction between these ent-kaurenes and ENBA followed second order kinetics. The descending order of reaction rates of the four ent-kaurenes was clearly showed as 1,1a, 2 and 2a. According to the Arrhenius equation,the activation energy of the overall reaction between

  14. [Analysis of Phytoplankton in Tsimlyansk Reservoir (RUSSIA) for the Presence of Cyanobacterial Hepato- and Neurotoxins].

    Science.gov (United States)

    Sidelev, S I; Golokolenova, T B; Chernova, E N; Russkikh, I V

    2015-01-01

    Although the water bodies of southern Russia experience the most extreme effects of cyanobacterial blooms, molecular genetic data on the composition of toxigenic cyanobacteria in this region have been absent. Screening for the genes responsible for the synthesis of hepatotoxins (microcystins and cylindrospermopsin) and neurotoxins (anatoxin-a and saxitoxins) in cyanobacteria from the Tsimlyansk reservoir on the Don River was carried out. The presence of microcystin-producing Microcystis and Planktothrix populations, as well as of cyanobacteria capable of synthesis of a neurotoxin anatoxin-a was revealed by polymerase chain reaction (PCR). A hypothesis of the presence of anatoxin-a-producing Planktothrix rubescens population in the phytoplankton of the Tsimlyansk reservoir is proposed. The obtained PCR data were confirmed by the results of enzyme-linked immunosorbent assay (ELISA) and liquid chromatography/mass-spectrometry (LC/MS). Anatoxin-a and five microcystin variants were identified in the phytoplankton biomass.

  15. Obturator internus muscle strains

    Directory of Open Access Journals (Sweden)

    Caoimhe Byrne, MB BCh, BAO

    2017-03-01

    Full Text Available We report 2 cases of obturator internus muscle strains. The injuries occurred in young male athletes involved in kicking sports. Case 1 details an acute obturator internus muscle strain with associated adductor longus strain. Case 2 details an overuse injury of the bilateral obturator internus muscles. In each case, magnetic resonance imaging played a crucial role in accurate diagnosis.

  16. A strain gauge

    DEFF Research Database (Denmark)

    2016-01-01

    The invention relates to a strain gauge of a carrier layer and a meandering measurement grid positioned on the carrier layer, wherein the strain gauge comprises two reinforcement members positioned on the carrier layer at opposite ends of the measurement grid in the axial direction....... The reinforcement members are each placed within a certain axial distance to the measurement grid with the axial distance being equal to or smaller than a factor times the grid spacing. The invention further relates to a multi-axial strain gauge such as a bi-axial strain gauge or a strain gauge rosette where each...... of the strain gauges comprises reinforcement members. The invention further relates to a method for manufacturing a strain gauge as mentioned above....

  17. Strain y strain rate para dummies

    Directory of Open Access Journals (Sweden)

    Pastor Olaya, MD

    2011-11-01

    Full Text Available Desarrollos recientes en el campo de la ecocardiografía han permitido a los cardiólogos cuantificar de manera objetiva la función miocárdica regional y global con base en los conceptos de deformación (strain y velocidad de deformación (strain rate que pueden calcularse de manera no invasiva tanto en el ventrículo izquierdo como en el derecho, y suministrar valiosa información en múltiples escenarios clínicos. Dado que esta técnica novedosa y promisoria se utiliza cada vez más en la clínica y en estudios de investigación, se hace necesario el conocimiento adecuado de sus principios, así como de sus aspectos técnicos, alcances y limitaciones para una mejor implementación. En este artículo se busca dar explicación a los conceptos fundamentales y las potenciales aplicaciones clínicas de la strain y la strain rate derivados por speckle tracking (strain 2D.

  18. ACTIVIDAD ANTIFUNGICA DEL EXTRACTO DE Brosimum rubescens (Palisangre

    Directory of Open Access Journals (Sweden)

    María Fachín-Espinar

    2012-12-01

    Full Text Available El extracto etanólico  y sus fracciones cromatográficas del tallo de Brosimum rubencens Taubert  fueron evaluados para determinar la actividad antifúngica in vitro mediante el método de macrodilución para hongos filamentosos. El tamizaje fitoquímico del extracto etanólico del tallo de B. rubencens evidenció la presencia de cumarinas, quinonas y taninos, además de flavonoides y triterpenos; para el estudio de la actividad antifúngica se utilizó cepas de Trichosporum rubrum ATCC 28188 y Trichosporum mentagrophytes ATCC 24953. En ambos casos la fracción insoluble en dilución ácida evidenció mayor actividad antifúngica que el extracto etanólico contra dermatofitos. El fraccionamiento del extracto etanólico permitió inferir que el responsables de la actividad se debe a los fitocomplejos, no así a las fracciones frente a T. rubrum ATCC 28188.

  19. ACTIVIDAD ANTIFUNGICA DEL EXTRACTO DE Brosimum rubescens (Palisangre

    Directory of Open Access Journals (Sweden)

    María Fachín Espinar

    2012-12-01

    Full Text Available El extracto etanólico y sus fracciones cromatográficas del tallo de Brosimum rubencens Taubert fueron evaluados para determinar la actividad antifúngica in vitro mediante el método de macrodilución para hongos filamentosos. El tamizaje fitoquímico del extracto etanólico del tallo de B. rubencens evidenció la presencia de cumarinas, quinonas y taninos, además de flavonoides y triterpenos; para el estudio de la actividad antifúngica se utilizó cepas de Trichosporum rubrum ATCC 28188 y Trichosporum mentagrophytes ATCC 24953. En ambos casos la fracción insoluble en dilución ácida evidenció mayor actividad antifúngica que el extracto etanólico contra dermatofitos. El fraccionamiento del extracto etanólico permitió inferir que el responsable de la actividad se debe a los fitocomplejos, no así a las fracciones frente a T. rubrum ATCC 28188.

  20. Three dimensional strained semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Voss, Lars; Conway, Adam; Nikolic, Rebecca J.; Leao, Cedric Rocha; Shao, Qinghui

    2016-11-08

    In one embodiment, an apparatus includes a three dimensional structure comprising a semiconductor material, and at least one thin film in contact with at least one exterior surface of the three dimensional structure for inducing a strain in the structure, the thin film being characterized as providing at least one of: an induced strain of at least 0.05%, and an induced strain in at least 5% of a volume of the three dimensional structure. In another embodiment, a method includes forming a three dimensional structure comprising a semiconductor material, and depositing at least one thin film on at least one surface of the three dimensional structure for inducing a strain in the structure, the thin film being characterized as providing at least one of: an induced strain of at least 0.05%, and an induced strain in at least 5% of a volume of the structure.

  1. Strain-engineered MOSFETs

    CERN Document Server

    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

  2. Sprains and Strains

    Science.gov (United States)

    ... and chronic. An acute strain occurs when a muscle becomes strained or pulled — or may even tear — when it stretches unusually far or abruptly. Acute ... and increases joint range of motion, making the muscles less tight and less prone to trauma ... Environmental conditions. Slippery or uneven surfaces can make ...

  3. Highly Strained Organophosphorus Compounds

    NARCIS (Netherlands)

    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

  4. Strain y strain rate para dummies Strain and strain rate for dummies

    Directory of Open Access Journals (Sweden)

    Pastor Olaya

    2011-12-01

    Full Text Available Desarrollos recientes en el campo de la ecocardiografía han permitido a los cardiólogos cuantificar de manera objetiva la función miocárdica regional y global con base en los conceptos de deformación (strain y velocidad de deformación (strain rate que pueden calcularse de manera no invasiva tanto en el ventrículo izquierdo como en el derecho, y suministrar valiosa información en múltiples escenarios clínicos. Dado que esta técnica novedosa y promisoria se utiliza cada vez más en la clínica y en estudios de investigación, se hace necesario el conocimiento adecuado de sus principios, así como de sus aspectos técnicos, alcances y limitaciones para una mejor implementación. En este artículo se busca dar explicación a los conceptos fundamentales y las potenciales aplicaciones clínicas de la strain y la strain rate derivados por speckle tracking (strain 2D.Recent developments in the field of echocardiography have allowed cardiologists to objectively quantify regional and global myocardial function based on the deformation (strain and strain rate which can be calculated non-invasively in both the left or right ventricle, and provide valuable information in multiple clinical settings. Since this new technique is promising and is being increasingly used in clinical and research studies, the adequate knowledge of its principles and its technical aspects, scope and limitations are necessary for its better implementation. This article seeks to explain fundamental concepts and potential clinical applications of strain and strain rate derived by speckle tracking (2D strain.

  5. Hamstring strain - aftercare

    Science.gov (United States)

    ... Elsevier Saunders; 2015:chap 88. Reider B, Davies GJ, Provencher MT. Muscle strains about the hip and thigh. In: Reider B, Davies GJ, Provencher MT, eds. Orthopaedic Rehabilitation of the Athlete . ...

  6. The strained state cosmology

    CERN Document Server

    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...

  7. Psychological strain between nurses

    Directory of Open Access Journals (Sweden)

    Andrea Obročníková

    2015-12-01

    Full Text Available Aim: The aim of the study was to identify differences in perception of work (mental workload among nurses providing acute and chronic nursing care. Design: Study design is cross-sectional and descriptive. Methods: The sample of respondents consisted of 97 nurses working in departments Neurology, Anesthesiology and Intensive Care Unit of the hospital St. James in Bardejov, University Hospital of L. Pasteur in Košice and University Hospital J. A. Reiman in Prešov. To measure psychological strain, Meister's questionnaire for neuropsychological strain was used. Results: Increased psychological strain was observed in nurses providing acute care versus nurses providing chronic care, particularly in job satisfaction, long-term tolerance, time constraints, high responsibility, nervousness, fatigue and satiety. In comparison with the population norm, nurses in acute care achieved significantly higher indicators of factor I (strain and gross score as nurses in neurological care. A statistically significant relationship between psychological stress and age of nurses working in anesthesiology and intensive care departments was confirmed. Nurses with long term practical experience are exposed to intense mental stress (especially in the areas of strain and monotony. Conclusion: The results of our study suggest the reality that variable qualities of work related strain among nurses can lead to physical and emotional exhaustion.

  8. Photothermal strain imaging

    Science.gov (United States)

    Choi, Changhoon; Ahn, Joongho; Jeon, Seungwan; Kim, Chulhong

    2017-07-01

    Vulnerable plaques are the major cause of cardiovascular disease, but they are difficult to detect with conventional intravascular imaging techniques. Techniques are needed to identify plaque vulnerability based on the presence of lipids in plaque. Thermal strain imaging (TSI) is an imaging technique based on ultrasound (US) wave propagation speed, which varies with the medium temperature. In TSI, the strain that occurs during tissue temperature change can be used for lipid detection because it has a different tendency depending on the type of tissue. Here, we demonstrate photothermal strain imaging (pTSI) using an intravascular ultrasound catheter. pTSI is performed by slightly and selectively heating lipid using a relatively inexpensive continuous laser source. We applied a speckle-tracking algorithm to US B-mode images for strain calculations. As a result, the strain produced in porcine fat was different from the strain produced in water-bearing gelatin phantom, which made it possible to distinguish the two. This suggests that pTSI could potentially be a way of differentiating lipids in coronary artery.

  9. Strain: Fact or Fiction?

    Science.gov (United States)

    Heilbronner, Renée

    2017-04-01

    2017 marks the 50th anniversary of the publication of John Ramsay's well known textbook "Folding and Fracturing of Rocks" - ... and the 30th anniversary of the rejection of a rather less well known paper entitled "Strain: Fact or Fiction?" submitted by Renée Panozzo to the Journal of Structural Geology. The gist of the paper was simple and straight forward: it was argued that not every fabric that can be observed in deformed rocks is necessarily a measure of the amount of strain the rock incurred. A distinction was made between a general "fabric", i.e., the traceable geometry of grain boundaries, for example, and a so-called "strain fabric", i.e., the model geometry that would result from homogeneously straining an initially isotropic fabric and that would exhibit at least orthorhombic symmetry. To verify if a given fabric was indeed a strain fabric it was therefore suggested to use the SURFOR method (published by Panozzo) and to carry out a so-called strain test, i.e., a check of symmetry, before interpreting the results of a fabric analysis in terms of strain. The problem with the paper was that it was very obviously written out of frustration. The frustration came form having reviewed a number of manuscripts which tried to use the then novel SURFOR method for strain analysis without first checking if the the fabric was a indeed a "strain fabric" or not, and then blaming the SURFOR method for producing ambiguous results. As a result, the paper was not exactly well balanced and carefully thought out. It was considered "interesting but not scholarly" by one of the reviewers and down-right offensive by the second. To tell the truth, however, the paper was not formally rejected. The editor Sue Treagus strongly encouraged Panozzo to revise the paper, ... and 30 years later, I will follow her advise and offer a revised paper as a tribute to John Ramsay. To quote from the original manuscript: "We should be a little more impressed that strain works so well, and less

  10. Microcystin Contamination in Sea Mussel Farms from the Italian Southern Adriatic Coast following Cyanobacterial Blooms in an Artificial Reservoir

    Directory of Open Access Journals (Sweden)

    De Pace Rita

    2014-01-01

    Full Text Available An experimental study was performed in 2009-2010 to investigate the polluting effect of eutrophic inland waters communicating with the sea coast. The study was planned after a heavy and long-lasting Planktothrix rubescens bloom occurred in the Lake Occhito, an artificial reservoir. The waters of the reservoir flow into the southern Adriatic Sea, near several marine breeding of Mytilus galloprovincialis mussels, a typical seafood from the Apulia region (Southern Italy. A monitoring study of water and mussels from the sea coast of northern Apulia region and on the Occhito reservoir was carried out over twelve months, to get more information regarding the contamination by cyanobacteria and related cyanotoxins. Elisa immunoassay analyses estimated total microcystin amounts from 1.73 to 256 ng/g in mussels, up to 0.61 μg/L in sea water and up to 298.7 μg/L in lake water. Analyses of some samples of free-living marine clams as well as of marine and freshwater fish proved microcystin contamination. Selective confirmatory analyses by LC/ESI-Q-ToF-MS/MS on some mussel samples identified the microcystin desMe-MC-RR as the major toxin; this compound has been reported in the literature as a specific marker toxin of Planktothrix rubescens blooms. Our study describes for the first time the direct relationship between environmental pollution and food safety, caused by seafood contamination from freshwater toxic blooms.

  11. Muscle strain injuries.

    Science.gov (United States)

    Garrett, W E

    1996-01-01

    One of the most common injuries seen in the office of the practicing physician is the muscle strain. Until recently, little data were available on the basic science and clinical application of this basic science for the treatment and prevention of muscle strains. Studies in the last 10 years represent action taken on the direction of investigation into muscle strain injuries from the laboratory and clinical fronts. Findings from the laboratory indicate that certain muscles are susceptible to strain injury (muscles that cross multiple joints or have complex architecture). These muscles have a strain threshold for both passive and active injury. Strain injury is not the result of muscle contraction alone, rather, strains are the result of excessive stretch or stretch while the muscle is being activated. When the muscle tears, the damage is localized very near the muscle-tendon junction. After injury, the muscle is weaker and at risk for further injury. The force output of the muscle returns over the following days as the muscle undertakes a predictable progression toward tissue healing. Current imaging studies have been used clinically to document the site of injury to the muscle-tendon junction. The commonly injured muscles have been described and include the hamstring, the rectus femoris, gastrocnemius, and adductor longus muscles. Injuries inconsistent with involvement of a single muscle-tendon junction proved to be at tendinous origins rather than within the muscle belly. Important information has also been provided regarding injuries with poor prognosis, which are potentially repairable surgically, including injuries to the rectus femoris muscle, the hamstring origin, and the abdominal wall. Data important to the management of common muscle injuries have been published. The risks of reinjury have been documented. The early efficacy and potential for long-term risks of nonsteroidal antiinflammatory agents have been shown. New data can also be applied to the field

  12. Well Conductor Strain Monitoring

    Science.gov (United States)

    2014-05-06

    comply with a collection of information if it does not display a currently valid OMB control number. 1. REPORT DATE JUL 2014 2. REPORT TYPE 3. DATES...849,429; filed on June 26, 2013 by the inventor, Dr. Anthony Ruffa and entitled “ SUBSEA WELL CONDUCTOR STRAIN MONITORING”. STATEMENT OF

  13. Strains in General Relativity

    CERN Document Server

    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.

  14. What Are Sprains and Strains?

    Science.gov (United States)

    ... hands and arms a lot. Examples are gymnastics, tennis, rowing, and golf. People who play these sports sometimes strain their hand or arm. Elbow strains can also happen when playing sports. What ...

  15. Strain measurement based battery testing

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jeff Qiang; Steiber, Joe; Wall, Craig M.; Smith, Robert; Ng, Cheuk

    2017-05-23

    A method and system for strain-based estimation of the state of health of a battery, from an initial state to an aged state, is provided. A strain gauge is applied to the battery. A first strain measurement is performed on the battery, using the strain gauge, at a selected charge capacity of the battery and at the initial state of the battery. A second strain measurement is performed on the battery, using the strain gauge, at the selected charge capacity of the battery and at the aged state of the battery. The capacity degradation of the battery is estimated as the difference between the first and second strain measurements divided by the first strain measurement.

  16. A strain gauge

    DEFF Research Database (Denmark)

    2017-01-01

    The invention relates to a strain gauge of a carrier layer and a meandering measurement grid (101) positioned on the carrier layer, wherein the measurement grid comprises a number of measurement grid sections placed side by side with gaps in between, and a number of end loops (106) interconnecting...... the measurement grid sections at their ends. The end loops at both ends of the measurement grid extend a length (L, 500) in the axial direction in millimetres of a factor times a ratio between a width of a grid section and the gap distance, wherein the factor is larger or equal to 1.5. The invention further...

  17. Sadovskii vortex in strain

    Science.gov (United States)

    Freilich, Daniel; Llewellyn Smith, Stefan

    2014-11-01

    A Sadovskii vortex is a patch of fluid with uniform vorticity surrounded by a vortex sheet. Using a boundary element type method, we investigate the steady states of this flow in an incompressible, inviscid straining flow. Outside the vortex, the fluid is irrotational. In the limiting case where the entire circulation is due to the vortex patch, this is a patch vortex (Moore & Saffman, Aircraft wake turbulence and its detection 1971). In the other limiting case, where all the circulation is due to the vortex sheet, this is a hollow vortex (Llewellyn Smith and Crowdy, J. Fluid Mech. 691, 2012). This flow has two governing nondimensional parameters, relating the strengths of the straining field, vortex sheet, and patch vorticity. We study the relationship between these two parameters, and examine the shape of the resulting vortices. We also work towards a bifurcation diagram of the steady states of the Sadovskii vortex in an attempt to understand the connection between vortex sheet and vortex patch desingularizations of the point vortex. Support from NSF-CMMI-0970113.

  18. Echocardiographic assessment of myocardial strain.

    Science.gov (United States)

    Gorcsan, John; Tanaka, Hidekazu

    2011-09-27

    Echocardiographic strain imaging, also known as deformation imaging, has been developed as a means to objectively quantify regional myocardial function. First introduced as post-processing of tissue Doppler imaging velocity converted to strain and strain rate, strain imaging has more recently also been derived from digital speckle tracking analysis. Strain imaging has been used to gain greater understanding into the pathophysiology of cardiac ischemia and infarction, primary diseases of the myocardium, and the effects of valvular disease on myocardial function, and to advance our understanding of diastolic function. Strain imaging has also been used to quantify abnormalities in the timing of mechanical activation for heart failure patients undergoing cardiac resynchronization pacing therapy. Further advances, such as 3-dimensional speckle tracking strain imaging, have emerged to provide even greater insight. Strain imaging has become established as a robust research tool and has great potential to play many roles in routine clinical practice to advance the care of the cardiovascular patient. This perspective reviews the physiology of myocardial strain, the technical features of strain imaging using tissue Doppler imaging and speckle tracking, their strengths and weaknesses, and the state-of-the-art present and potential future clinical applications.

  19. Colony Dimorphism in Bradyrhizobium Strains

    Science.gov (United States)

    Sylvester-Bradley, Rosemary; Thornton, Philip; Jones, Peter

    1988-01-01

    Ten isolates of Bradyrhizobium spp. which form two colony types were studied; the isolates originated from a range of legume species. The two colony types differed in the amount of gum formed or size or both, depending on the strain. Whole 7-day-old colonies of each type were subcultured to determine the proportion of cells which had changed to the other type. An iterative computerized procedure was used to determine the rate of switching per generation between the two types and to predict proportions reached at equilibrium for each strain. The predicted proportions of the wetter (more gummy) or larger colony type at equilibrium differed significantly between strains, ranging from 0.9999 (strain CIAT 2383) to 0.0216 (strain CIAT 2469), because some strains switched faster from dry to wet (or small to large) and others switched faster from wet to dry (or large to small). Predicted equilibrium was reached after about 140 generations in strain USDA 76. In all but one strain (CIAT 3030) the growth rate of the wetter colony type was greater than or similar to that of the drier type. The mean difference in generation time between the two colony types was 0.37 h. Doubling times calculated for either colony type after 7 days of growth on the agar surface ranged from 6.0 to 7.3 h. The formation of two persistent colony types by one strain (clonal or colony dimorphism) may be a common phenomenon among Bradyrhizobium strains. Images PMID:16347599

  20. Strain Pattern in Supercooled Liquids

    Science.gov (United States)

    Illing, Bernd; Fritschi, Sebastian; Hajnal, David; Klix, Christian; Keim, Peter; Fuchs, Matthias

    2016-11-01

    Investigations of strain correlations at the glass transition reveal unexpected phenomena. The shear strain fluctuations show an Eshelby-strain pattern [˜cos (4 θ ) /r2 ], characteristic of elastic response, even in liquids, at long times. We address this using a mode-coupling theory for the strain fluctuations in supercooled liquids and data from both video microscopy of a two-dimensional colloidal glass former and simulations of Brownian hard disks. We show that the long-ranged and long-lived strain signatures follow a scaling law valid close to the glass transition. For large enough viscosities, the Eshelby-strain pattern is visible even on time scales longer than the structural relaxation time τ and after the shear modulus has relaxed to zero.

  1. Hydrogen production from microbial strains

    Science.gov (United States)

    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.

  2. Evaluation of Strain Hardening Parameters

    Institute of Scientific and Technical Information of China (English)

    DING Zong-hai; Pavel Huml; YANG Wei

    2004-01-01

    The plane-strain compression test for three kinds of materials was carried out in a temperature range between room temperature and 400 ℃. The σ - ε curves and strain-hardening rate at different temperatures were simulated and a reasonable fit to the experimental data was obtained. A modified model created by data inference and computer simulation was developed to describe the strain hardening at a large deformation, and the predicted strain hardening are in a good agreement with that observed in a large range of stress. The influences of different parameters on strain hardening behaviour under large deformation were analysed. The temperature increase within the test temperatures for stainless steel 18/8 Ti results in dropping of flow stress and strain-hardening rate. For favourable γ-fibre texture to obtain high r, the cold rolling was applied at large reduction. In the experimental procedure, the X-ray diffraction test was carried out to compare the strain hardening and microstructure under large deformation for a bcc steel (low carbon steel SS-1142). The results indicate that the high strain-hardening rate possibly occurs when the primary slip plane {110} is parallel to the rolling plane and the strain-hardening rate decreases when lots of {110} plane rotate out from the orientation {110}∥RP.

  3. Strain correction in interleaved strain-encoded (SENC) cardiac MR

    Science.gov (United States)

    Motaal, Abdallah G.; Osman, Nael F.

    2010-03-01

    The strain encoding (SENC) technique directly encodes regional strain of the heart into the acquired MR images and produces two images with two different tunings so that longitudinal strain, on the short-axis view, or circumferential strain on the long-axis view, are measured. Interleaving acquisition is used to shorten the acquisition time of the two tuned images by 50%, but it suffers from errors in the strain calculations due to inter-tunings motion of the heart. In this work, we propose a method to correct for the inter-tunings motion by estimating the motion-induced shift in the spatial frequency of the encoding pattern, which depends on the strain rate. Numerical data was generated to test the proposed method and real images of human subjects were used for validation. The proposed method corrected the measured strain values so they became nearly identical to the original ones. The results show an improvement in strain calculations so as to relax the imaging constraints on spatial and temporal resolutions and improve image quality.

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

    CERN Document Server

    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.

  5. Strained graphene Hall bar

    Science.gov (United States)

    Milovanović, S. P.; Peeters, F. M.

    2017-02-01

    The effects of strain, induced by a Gaussian bump, on the magnetic field dependent transport properties of a graphene Hall bar are investigated. The numerical simulations are performed using both classical and quantum mechanical transport theory and we found that both approaches exhibit similar characteristic features. The effects of the Gaussian bump are manifested by a decrease of the bend resistance, R B, around zero-magnetic field and the occurrence of side-peaks in R B. These features are explained as a consequence of bump-assisted scattering of electrons towards different terminals of the Hall bar. Using these features we are able to give an estimate of the size of the bump. Additional oscillations in R B are found in the quantum description that are due to the population/depopulation of Landau levels. The bump has a minor influence on the Hall resistance even for very high values of the pseudo-magnetic field. When the bump is placed outside the center of the Hall bar valley polarized electrons can be collected in the leads.

  6. Residual strains in conduit arteries.

    Science.gov (United States)

    Rachev, A; Greenwald, S E

    2003-05-01

    Residual strains and stresses are those that exist in a body when all external loads are removed. Residual strains in arteries can be characterized by the opening angle of the sector-like cross-section which arises when an unloaded ring segment is radially cut. A review of experimental methods for measuring residual strains and the main results about the variation of the opening angle with arterial localization, age, smooth muscle activity, mechanical environment and certain vascular pathologies are presented and discussed. It is shown that, in addition to their well-established ability to homogenize the stress field in the arterial wall, residual strains make arteries more compliant and thereby improve their performance as elastic reservoirs and ensure more effective local control of the arterial lumen by smooth muscle cells. Finally, evidence that, in some cases, residual strains remain in arteries even after they have been cut radially is discussed.

  7. High temperature strain measurement with a resistance strain gage

    Science.gov (United States)

    Lei, Jih-Fen; Fichtel, ED; Mcdaniel, Amos

    1993-01-01

    A PdCr based electrical resistance strain gage was demonstrated in the laboratory to be a viable sensor candidate for static strain measurement at high temperatures. However, difficulties were encountered while transferring the sensor to field applications. This paper is therefore prepared for recognition and resolution of the problems likely to be encountered with PdCr strain gages in field applications. Errors caused by the measurement system, installation technique and lead wire attachment are discussed. The limitations and some considerations related to the temperature compensation technique used for this gage are also addressed.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  9. Roll bonding of strained aluminium

    DEFF Research Database (Denmark)

    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...... 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...

  10. Roll bonding of strained aluminium

    DEFF Research Database (Denmark)

    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...... 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...

  11. Canning Tests on Mushroom Strain

    OpenAIRE

    Gormley, T. R. (Thomas Ronan); MacCanna, C.

    1980-01-01

    Canning tests were carried out on 5 mushroom strains from 2 flushes of 4 separate crops. Particular attention was given to the ratio of whole closed canned mushrooms to that of whole closed canned mushrooms plus canned stems and pieces - i.e. total yield. Factors considered in the tests included grading prior to processing, blanching and retort losses, shrinkage in size and mushroom whiteness. Cream and off-white strains had the highest level of open and misshapen mushrooms prior to processin...

  12. PLASTICITY AND NON-LINEAR ELASTIC STRAINS

    Science.gov (United States)

    conditions existing in plane waves in an extended medium to give the time rate of change of stress as a function of the time rate of change of strain, the stress invariants, the total strain and the plastic strain. (Author)

  13. Protein (Cyanobacteria): 652400722 [PGDBj - Ortholog DB

    Lifescience Database Archive (English)

    Full Text Available pothetical protein Planktothrix prolifica MSEWMPLPFPKCPRCHDSWVKSYHDCFSNGEVLVEPYQRQAKCCGCSKQWDLLNSNFNCSCGYTFSASEVENALSTTQLLKQRLIQKLNEMDSFERSITTKSQSSFKQWIGSISYEIGKLLGTTASQAKQLIDNFFEKWSS

  14. Effective Hamiltonian of strained graphene.

    Science.gov (United States)

    Linnik, T L

    2012-05-23

    Based on the symmetry properties of the graphene lattice, we derive the effective Hamiltonian of graphene under spatially nonuniform acoustic and optical strains. Comparison with the published results of the first-principles calculations allows us to determine the values of some Hamiltonian parameters, and suggests the validity of the derived Hamiltonian for acoustical strain up to 10%. The results are generalized for the case of graphene with broken plane reflection symmetry, which corresponds, for example, to the case of graphene placed on a substrate. Here, essential modifications to the Hamiltonian give rise, in particular, to the gap opening in the spectrum in the presence of the out-of-plane component of optical strain, which is shown to be due to the lifting of the sublattice symmetry. The developed effective Hamiltonian can be used as a convenient tool for analysis of a variety of strain-related effects, including electron-phonon interaction or pseudo-magnetic fields induced by the nonuniform strain.

  15. Presence of Potential Toxin-Producing Cyanobacteria in an Oligo-Mesotrophic Lake in Baltic Lake District, Germany: An Ecological, Genetic and Toxicological Survey

    Directory of Open Access Journals (Sweden)

    Pawan K. Dadheech

    2014-09-01

    Full Text Available Massive developments of potentially toxic cyanobacteria in Lake Stechlin, an oligo-mesotrophic lake in the Baltic Lake District of Germany raised concerns about toxic contamination of these important ecosystems. Field samples in the phase of mass developments of cyanobacteria were used for genetic and toxicological analyses. Microcystins and microcystin genes were detected in field samples of the lake for the first time. However, the toxins were not produced by the dominant taxa (Dolichospermum circinale and Aphanizomenon flos-aquae but by taxa, which were present only in low biomass in the samples (Microcystis cf. aeruginosa and Planktothrix rubescens. The phytoplankton successions during the study period revealed an increase of cyanobacterial populations. The findings contribute to the changes that have been investigated in Lake Stechlin since the mid-1990s. The possible reasons behind these developments may be climate change, special weather conditions and an increased nutrient pool.

  16. Presence of potential toxin-producing cyanobacteria in an oligo-mesotrophic lake in Baltic Lake District, Germany: an ecological, genetic and toxicological survey.

    Science.gov (United States)

    Dadheech, Pawan K; Selmeczy, Géza B; Vasas, Gábor; Padisák, Judit; Arp, Wolfgang; Tapolczai, Kálmán; Casper, Peter; Krienitz, Lothar

    2014-09-29

    Massive developments of potentially toxic cyanobacteria in Lake Stechlin, an oligo-mesotrophic lake in the Baltic Lake District of Germany raised concerns about toxic contamination of these important ecosystems. Field samples in the phase of mass developments of cyanobacteria were used for genetic and toxicological analyses. Microcystins and microcystin genes were detected in field samples of the lake for the first time. However, the toxins were not produced by the dominant taxa (Dolichospermum circinale and Aphanizomenon flos-aquae) but by taxa, which were present only in low biomass in the samples (Microcystis cf. aeruginosa and Planktothrix rubescens). The phytoplankton successions during the study period revealed an increase of cyanobacterial populations. The findings contribute to the changes that have been investigated in Lake Stechlin since the mid-1990s. The possible reasons behind these developments may be climate change, special weather conditions and an increased nutrient pool.

  17. Intergranular strains in textured steel

    Energy Technology Data Exchange (ETDEWEB)

    Daymond, M.R. [Los Alamos Neutron Science Center (LANSCE), Los Alamos, NM (United States); Tome, C.N. [Los Alamos National Lab., NM (United States). Materials Science and Technology Div.; Bourke, M.A.M. [Los Alamos Neutron Science Center (LANSCE), Los Alamos, NM (United States); Los Alamos National Lab., NM (United States). Materials Science and Technology Div.

    2000-07-01

    Tensile specimens were machined from heat treated austenitic stainless steel plate prior to and after 70% reduction by uni-directional rolling. In addition to a specimen from the as-received plate, two specimens were cut from the rolled plate, with axes parallel and perpendicular to the rolling direction respectively. In situ measurements of the strain response of multiple hkl lattice planes to an applied uniaxial tensile load were made using neutron diffraction. The experimental results are compared with predictions from a self-consistent Hill-Hutchinson model. The measured texture in the plate was approximately 3 times random, however its effect on the hkl response was small compared to the residual strains left by rolling. The apparent elastic modulus and Poisson's ratios of the planes is affected by the residual strains, which is attributed to the effect of micro-plasticity. Interpretation of residual stress measurements is considered in light of these results. (orig.)

  18. Strain Growth in Containment Vessels

    Institute of Scientific and Technical Information of China (English)

    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.

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

    Directory of Open Access Journals (Sweden)

    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

  20. Photoacoustic spectroscopy of Entamoeba histolytica strains

    Science.gov (United States)

    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.

  1. [Selected properties of Bacteroides fragilis enterotoxigenic strains].

    Science.gov (United States)

    Rokosz, A; Meisel-Mikołajczyk, F

    1995-01-01

    Seven B. fragilis strains were examined. One strain was reference, non-enterotoxigenic, representing serotype E2 according to Beerens et al. (1971). Six strains produced enterotoxin (ETBF). Four of them were isolated from human feces and two of them from swine feces. All strains were investigated morphologically, biochemically (ATB Expression, France) and by means of direct immunofluorescence (Bacteroides--IF test, Poland). Their resistance to chemotherapeutics was tested (ATB Expression, France). The MIC values of clindamycin and metronidazole were determined using E test strips (AB Biodisk, Sweden). Each strain formed capsules. The percentage of encapsulated cells was high (80-100%). Some strains produced thick capsules. Biochemical patterns were similar and typical for B. fragilis rods. One enterotoxigenic strain produced gelatinase and three ETBF strains fermented trehalose. All strains reacted in direct immunofluorescence exclusively with conjugate against serotype E of BFG. Thus, each strain showed antigenic pattern E. Drug susceptibility of all strains was similar. One enterotoxigenic strain was resistant to clindamycin. All strains were susceptible to metronidazole. These studies indicate that on the basis of morphological, biochemical and serological features (IF), enterotoxigenic B. fragilis strains cannot be distinguished from the nonenterotoxigenic one. Also, the correlation between toxigenicity and drug sensitivity of the examined strains is not observed.

  2. Extreme Temperature Strain Measurement System

    Science.gov (United States)

    1990-08-01

    Road, Lantham, New York 12110, Phone (518) 785-2323, noncontacting, " Fotonic " fiber bundle sensor * Dual Core Fiber Optic Strain Gage with Laser input...Lantham, New York 12110, Phone (518) 456-4131, Reflective Light, Fiber bundles, " Fotonic Sensors", to 600°F "• Moire’ Technique, optical interference

  3. Asymptomatic bacteriuria Escherichia coli strains

    DEFF Research Database (Denmark)

    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...

  4. Bacteriocins and novel bacterial strains.

    Science.gov (United States)

    Poultry is thought to be a significant source of Campylobacter in human disease. We evaluated anti-Campylobacter activity among 365 Bacillus and Paenibacillus isolates from poultry. One novel antagonistic Bacillus circulans and three Paenibacillus polymyxa strains were identified and further studi...

  5. Job strain and alcohol intake

    DEFF Research Database (Denmark)

    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....

  6. Asymptomatic bacteriuria Escherichia coli strains

    DEFF Research Database (Denmark)

    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...

  7. Computational strain gradient crystal plasticity

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Kysar, Jeffrey W.

    2014-01-01

    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...

  8. Job strain and tobacco smoking

    DEFF Research Database (Denmark)

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

    2012-01-01

    Tobacco smoking is a major contributor to the public health burden and healthcare costs worldwide, but the determinants of smoking behaviours are poorly understood. We conducted a large individual-participant meta-analysis to examine the extent to which work-related stress, operationalised as job...... strain, is associated with tobacco smoking in working adults....

  9. Amino acid availability determines the ratio of microcystin variants in the cyanobacterium Planktothrix agardhii

    NARCIS (Netherlands)

    Tonk, L.; van de Waal, D.B.; Slot, P.; Huisman, J.; Matthijs, H.C.P.; Visser, P.M.

    2008-01-01

    Cyanobacteria are capable of producing multiple microcystin variants simultaneously. The mechanisms that determine the composition of microcystin variants in cyanobacteria are still debated. [Asp3]microcystin-RR contains arginine at the position where the more toxic [Asp3]microcystin-LR incorporates

  10. High Strain, Strain Rate Behavior of PTFE/Al/W

    Science.gov (United States)

    Addiss, John; Cai, Jing; Walley, Steve; Proud, William; Nesterenko, Vitali

    2007-06-01

    Conventional dropweight technique was modified to accommodate low amplitude signals from low strength, cold isostatically pressed energetic ``heavy'' composites of polytetrafluoroethylene (PTFE)/AL/W. The fracture strength, strain and post-critical behaviour of fractured samples were measured for samples of different porosity and W grain size (the masses of each component being the same in each case). Unusual phenomenon of significantly higher strength (55 MPa) of porous composites (density 5.9 g/cc) with small tungsten particles (1 micron) in comparison with strength (32 MPa) of dense composites (7.1 g/cc) with larger tungsten particles (20 micron) was observed. This is attributed to force chains created by a network of small tungsten particles. Interrupted tests at the different level of strains revealed mechanism of fracture under dynamic compression.

  11. A NEW STRAIN OF TRANSMISSIBLE LEUCEMIA IN FOWLS (STRAIN H).

    Science.gov (United States)

    Ellermann, V

    1921-03-31

    1. A new strain of fowl leucosis has been transmitted through twelve generations of fowls. 2. An increase in virulence was observed during its passage. This was shown in a shortening of the interval between inoculation and death. The increase in virulence does not affect the number of successful inoculations, which remains approximately constant in from 20 to 40 per cent of the birds employed. 3. As with former strains, the disease manifests itself in various forms; i.e., myeloid and intravascular lymphoid types. A single lymphatic case was observed. 4. In several intravascular cases a diminution in the hemolytic power of the serum was established. This phenomenon was absent in a number of myeloid cases. 5. Active immunization cannot be produced by means of the subcutaneous injection of virulent material. 6. The finding of previous experiments that the virus is filterable has been confirmed. 7. The inoculation of human leucemic material into fowls gave negative results.

  12. Strains

    Science.gov (United States)

    ... N, Rodeo SA, Alini M, Maher S, et al. Physiology and pathophysiology of musculoskeletal tissues. In: Miller MD, Thompson SR, eds. DeLee and Drez's Orthopaedic Sports Medicine . 4th ed. Philadelphia, PA: Elsevier Saunders; 2015: ...

  13. Modelling to very high strains

    Science.gov (United States)

    Bons, P. D.; Jessell, M. W.; Griera, A.; Evans, L. A.; Wilson, C. J. L.

    2009-04-01

    Ductile strains in shear zones often reach extreme values, resulting in typical structures, such as winged porphyroclasts and several types of shear bands. The numerical simulation of the development of such structures has so far been inhibited by the low maximum strains that numerical models can normally achieve. Typical numerical models collapse at shear strains in the order of one to three. We have implemented a number of new functionalities in the numerical platform "Elle" (Jessell et al. 2001), which significantly increases the amount of strain that can be achieved and simultaneously reduces boundary effects that become increasingly disturbing at higher strain. Constant remeshing, while maintaining the polygonal phase regions, is the first step to avoid collapse of the finite-element grid required by finite-element solvers, such as Basil (Houseman et al. 2008). The second step is to apply a grain-growth routine to the boundaries of polygons that represent phase regions. This way, the development of sharp angles is avoided. A second advantage is that phase regions may merge or become separated (boudinage). Such topological changes are normally not possible in finite element deformation codes. The third step is the use of wrapping vertical model boundaries, with which optimal and unchanging model boundaries are maintained for the application of stress or velocity boundary conditions. The fourth step is to shift the model by a random amount in the vertical direction every time step. This way, the fixed horizontal boundary conditions are applied to different material points within the model every time step. Disturbing boundary effects are thus averaged out over the whole model and not localised to e.g. top and bottom of the model. Reduction of boundary effects has the additional advantage that model can be smaller and, therefore, numerically more efficient. Owing to the combination of these existing and new functionalities it is now possible to simulate the

  14. Engineering piezoresistivity using biaxially strained silicon

    DEFF Research Database (Denmark)

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

    2008-01-01

    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 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...

  15. Beryllium strain under dynamic loading

    Directory of Open Access Journals (Sweden)

    Pushkov Victor

    2015-01-01

    Full Text Available There are some data (not much on dynamic characteristics of beryllium that are important, for example, when estimating construction performance at NPP emergencies. A number of data on stress-strain curves, spall strength, shear strength, fracture and structure responses of shock loaded beryllium have obtained in US and Russian laboratories. For today the model description of this complex metal behavior does not have a reasonable agreement with the experimental data, thus a wider spectrum of experimental data is required. This work presents data on dynamic compression-test diagrams of Russian beryllium. Experiments are performed using Hopkinson bar method (SHPB. Strain rates were ε ∼ 103 s−1.

  16. Strain-Detecting Composite Materials

    Science.gov (United States)

    Wallace, Terryl A. (Inventor); Smith, Stephen W. (Inventor); Piascik, Robert S. (Inventor); Horne, Michael R. (Inventor); Messick, Peter L. (Inventor); Alexa, Joel A. (Inventor); Glaessgen, Edward H. (Inventor); Hailer, Benjamin T. (Inventor)

    2016-01-01

    A composite material includes a structural material and a shape-memory alloy embedded in the structural material. The shape-memory alloy changes crystallographic phase from austenite to martensite in response to a predefined critical macroscopic average strain of the composite material. In a second embodiment, the composite material includes a plurality of particles of a ferromagnetic shape-memory alloy embedded in the structural material. The ferromagnetic shape-memory alloy changes crystallographic phase from austenite to martensite and changes magnetic phase in response to the predefined critical macroscopic average strain of the composite material. A method of forming a composite material for sensing the predefined critical macroscopic average strain includes providing the shape-memory alloy having an austenite crystallographic phase, changing a size and shape of the shape-memory alloy to thereby form a plurality of particles, and combining the structural material and the particles at a temperature of from about 100-700.degree. C. to form the composite material.

  17. Spectral Psychoanalysis of Speech under Strain | Sharma ...

    African Journals Online (AJOL)

    Spectral Psychoanalysis of Speech under Strain. ... Different voice features from the speech signal to be influenced by strain are: loudness, fundamental frequency, jitter, zero-crossing rate, ... EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT

  18. Strain Monitoring of Flexible Structures

    Science.gov (United States)

    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.

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

    DEFF Research Database (Denmark)

    Jensen, L.; Petersen, E.; Henriksen, S.A.;

    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...... strains, as demonstrated on a further six T. gondii reference strains [BK and GT1 (group A), NTE and 561 (group B), and NED and C56 (group C)]. The bradyzoite-specific mAb, 4.3, reacted to the GT1, NTE and 561 strains, but not to the BK, NED or C56 strains. The tachyzoite-specific mAb, 4.25, reacted....... gondii strain collection representative for a small geographic area (Denmark) was established within a short time span from a variety of animal species. Using the mAb as typing reagents to this Danish strain collection, all 36 animal and two human strains were identified as having the same reaction...

  20. EFFECTIVE STRESS AND STRAIN IN FINITE DEFORMATION

    Institute of Scientific and Technical Information of China (English)

    周喆; 秦伶俐; 黄文彬; 王红卫

    2004-01-01

    Whether the concept of effective stress and strain in elastic-plastic theory is still valid under the condition of finite deformation was mainly discussed. The uni-axial compression experiments in plane stress and plane strain states were chosen for study. In the two kinds of stress states, the stress- strain curve described by logarithm strain and rotated Kirchhoff stress matches the experiments data better than the curves defined by other stressstrain description.

  1. Piezoelectric field in strained GaAs.

    Energy Technology Data Exchange (ETDEWEB)

    Chow, Weng Wah; Wieczorek, Sebastian Maciej

    2005-11-01

    This report describes an investigation of the piezoelectric field in strained bulk GaAs. The bound charge distribution is calculated and suitable electrode configurations are proposed for (1) uniaxial and (2) biaxial strain. The screening of the piezoelectric field is studied for different impurity concentrations and sample lengths. Electric current due to the piezoelectric field is calculated for the cases of (1) fixed strain and (2) strain varying in time at a constant rate.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  4. Strain Imaging Using Terahertz Waves and Metamaterials

    Science.gov (United States)

    2016-11-01

    TECHNICAL REPORT RDMR-WD-16-48 STRAIN IMAGING USING TERAHERTZ WAVES AND METAMATERIALS Henry O. Everitt and Martin S...TITLE AND SUBTITLE Strain Imaging Using Terahertz Waves and Metamaterials 5. FUNDING NUMBERS 6. AUTHOR(S) Henry O. Everitt, Martin S...technique to measure strain in opaque objects. Experiments were conducted utilizing metamaterials on polydimethylsiloxane (PDMS) sheets to produce

  5. Antigenic differentiation of classical swine fever vaccinal strain PAV-250 from other strains, including field strains from Mexico.

    Science.gov (United States)

    Mendoza, Susana; Correa-Giron, Pablo; Aguilera, Edgar; Colmenares, Germán; Torres, Oscar; Cruz, Tonatiuh; Romero, Andres; Hernandez-Baumgarten, Eliseo; Ciprián, Abel

    2007-10-10

    Twenty-nine classical swine fever virus (CSFv) strains were grown in the PK15 or SK6 cell lines. Antigenic differentiation studies were performed using monoclonal antibodies (McAbs), produced at Lelystad (CDI-DLO), The Netherlands. The monoclonals which were classified numerically as monoclonals 2-13. Epitope map patterns that resulted from the reactivity with McAbs were found to be unrelated to the pathogenicity of the viruses studied. Antigenic determinants were recognized by McAbs 5 and 8, were not detected in some Mexican strains; however, sites for McAb 6 were absent in all strains. The PAV-250 vaccine strain was recognized by all MAbs, except by MAb 6. Furthermore, the Chinese C-S vaccine strain was found to be very similar to the GPE(-) vaccine. None of the studied Mexican vaccines or field strains was found to be similar to the PAV-250 vaccine strain.

  6. Spontaneous abortion and physical strain around implantation

    DEFF Research Database (Denmark)

    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...

  7. On lower order strain gradient plasticity theories

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Hutchinson, J. W.

    2003-01-01

    the tangent moduli governing increments of stress and strain. It is shown that the modification is far from benign from a mathematical standpoint, changing the qualitative character of solutions and leading to a new type of localization that is at odds with what is expected from a strain gradient theory......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 findings raise questions about the physical acceptability of this class of strain gradient theories....

  8. Spontaneous abortion and physical strain around implantation

    DEFF Research Database (Denmark)

    Hjøllund, Niels Henrik Ingvar; Jensen, T.K.; Bonde, J.P.

    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...

  9. Demonstration test of burner liner strain measurements using resistance strain gages

    Science.gov (United States)

    Grant, H. P.; Anderson, W. L.

    1984-01-01

    A demonstration test of burner liner strain measurements using resistance strain gages as well as a feasibility test of an optical speckle technique for strain measurement are presented. The strain gage results are reported. Ten Kanthal A-1 wire strain gages were used for low cycle fatigue strain measurements to 950 K and .002 apparent strain on a JT12D burner can in a high pressure (10 atmospheres) burner test. The procedure for use of the strain gages involved extensive precalibration and postcalibration to correct for cooling rate dependence, drift, and temperature effects. Results were repeatable within + or - .0002 to .0006 strain, with best results during fast decels from 950 K. The results agreed with analytical prediction based on an axisymmetric burner model, and results indicated a non-uniform circumferential distribution of axial strain, suggesting temperature streaking.

  10. Enhanced dopant solubility in strained silicon

    Energy Technology Data Exchange (ETDEWEB)

    Adey, J [School of Physics, University of Exeter, Exeter EX4 4QL (United Kingdom); Jones, R [School of Physics, University of Exeter, Exeter EX4 4QL (United Kingdom); Briddon, P R [Physics Centre, School of Natural Science, Newcastle upon Tyne NE1 7RU (United Kingdom)

    2004-12-22

    The effect of biaxial strain on the solubility of the common donor arsenic and acceptor boron is calculated using spin-polarized local density functional theory. The change in solubility with strain is considered in terms of contributions from the change in total energy and Fermi energy with strain. The solubility of boron is found to be enhanced by compressive biaxial strain due to a reduction in the total energy of the small substitutional impurity and an increase in the Fermi energy for compressive strain. The solubility of arsenic is shown to be enhanced by tensile strain and this is due entirely to the change in Fermi energy. For boron as well as arsenic the change in Fermi energy with strain is shown to make the dominant contribution.

  11. Multiplicative earthquake likelihood models incorporating strain rates

    Science.gov (United States)

    Rhoades, D. A.; Christophersen, A.; Gerstenberger, M. C.

    2017-01-01

    SUMMARYWe examine the potential for strain-rate variables to improve long-term earthquake likelihood models. We derive a set of multiplicative hybrid earthquake likelihood models in which cell rates in a spatially uniform baseline model are scaled using combinations of covariates derived from earthquake catalogue data, fault data, and strain-rates for the New Zealand region. Three components of the strain rate estimated from GPS data over the period 1991-2011 are considered: the shear, rotational and dilatational strain rates. The hybrid model parameters are optimised for earthquakes of M 5 and greater over the period 1987-2006 and tested on earthquakes from the period 2012-2015, which is independent of the strain rate estimates. The shear strain rate is overall the most informative individual covariate, as indicated by Molchan error diagrams as well as multiplicative modelling. Most models including strain rates are significantly more informative than the best models excluding strain rates in both the fitting and testing period. A hybrid that combines the shear and dilatational strain rates with a smoothed seismicity covariate is the most informative model in the fitting period, and a simpler model without the dilatational strain rate is the most informative in the testing period. These results have implications for probabilistic seismic hazard analysis and can be used to improve the background model component of medium-term and short-term earthquake forecasting models.

  12. Computational Strain Gradient Crystal Plasticity

    DEFF Research Database (Denmark)

    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...... element solution method is presented, which delivers the slip-rate field and the velocity-field based on two minimum principles. Some plane deformation problems relevant for certain specific orientations of a face centered cubic crystal under plane loading conditions are studied, and effective in......-plane parameters are developed based on the crystallographic properties of the material. The problem of cyclic shear of a single crystal between rigid platens is studied as well as void growth of a cylindrical void....

  13. Determining Micromechanical Strain in Nitinol

    Energy Technology Data Exchange (ETDEWEB)

    Strasberg, Matthew; /SLAC

    2006-09-27

    Nitinol is a superelastic alloy made of equal parts nickel and titanium. Due to its unique shape memory properties, nitinol is used to make medical stents, lifesaving devices used to allow blood flow in occluded arteries. Micromechanical models and even nitinol-specific finite element analysis (FEA) software are insufficient for unerringly predicting fatigue and resultant failure. Due to the sensitive nature of its application, a better understanding of nitinol on a granular scale is being pursued through X-ray diffraction techniques at the Stanford Synchrotron Radiation Laboratory (SSRL) at the Stanford Linear Accelerator Center (SLAC). Through analysis of powder diffraction patterns of nitinol under increasing tensile loads, localized strain can be calculated. We compare these results with micromechanical predictions in order to advance nitinol-relevant FEA tools. From this we hope to gain a greater understanding of how nitinol fatigues under multi-axial loads.

  14. Sensor for Measuring Strain in Textile

    Directory of Open Access Journals (Sweden)

    Gerhard Tröster

    2008-06-01

    Full Text Available In this paper a stain sensor to measure large strain (80% in textiles is presented. It consists of a mixture of 50wt-% thermoplastic elastomer (TPE and 50wt-% carbon black particles and is fiber-shaped with a diameter of 0.315mm. The attachment of the sensor to the textile is realized using a silicone film. This sensor configuration was characterized using a strain tester and measuring the resistance (extension-retraction cycles: It showed a linear resistance response to strain, a small hysteresis, no ageing effects and a small dependance on the strain velocity. The total mean error caused by all these effects was +/-5.5% in strain. Washing several times in a conventional washing machine did not influence the sensor properties. The paper finishes by showing an example application where 21 strain sensors were integrated into a catsuit. With this garment, 27 upper body postures could be recognized with an accuracy of 97%.

  15. Job Strain in Shift and Daytime Workers.

    Science.gov (United States)

    Knutsson; Nilsson

    1997-07-01

    Cross-sectional questionnaire data were used to compare the levels of job strain in shift and daytime workers. Job strain was measured according to Karasek's Demands/Discretion model. Four occupational groups were included: drivers, industrial workers, policemen/watchmen, and cooks. The study subjects were a random sample of 508 daytime workers and 418 shift workers. Job demand did not differentiate between shift and daytime workers, comparing groups broken down by gender and by occupation. The daytime workers reported higher levels of job strain than the shift workers, and women experienced a higher level of job strain than did men. Multiple linear regression analysis showed that only occupational group and gender predicted job strain level. Shiftwork was not significantly associated with job strain in the regression model.

  16. The many shades of prion strain adaptation.

    Science.gov (United States)

    Baskakov, Ilia V

    2014-01-01

    In several recent studies transmissible prion disease was induced in animals by inoculation with recombinant prion protein amyloid fibrils produced in vitro. Serial transmission of amyloid fibrils gave rise to a new class of prion strains of synthetic origin. Gradual transformation of disease phenotypes and PrP(Sc) properties was observed during serial transmission of synthetic prions, a process that resembled the phenomenon of prion strain adaptation. The current article discusses the remarkable parallels between phenomena of prion strain adaptation that accompanies cross-species transmission and the evolution of synthetic prions occurring within the same host. Two alternative mechanisms underlying prion strain adaptation and synthetic strain evolution are discussed. The current article highlights the complexity of the prion transmission barrier and strain adaptation and proposes that the phenomenon of prion adaptation is more common than previously thought.

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

    DEFF Research Database (Denmark)

    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 decre......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...

  18. On inhomogeneous straining in compressed sylvinite

    Science.gov (United States)

    Barannikova, S. A.; Nadezhkin, M. V.; Zuev, L. B.; Zhigalkin, V. M.

    2010-06-01

    Spatiotemporal distributions of local components of the distortion tensor of quasi-plastic materials—saliferous rocks (sylvinite)—have been studied under active compressive straining conditions using double-exposure speckle photography techniques. The strain localization patterns are presented and the features of macroscopic strain inhomogeneity are considered for inelastic behavior of the material. Results obtained for the slow wave processes in deformed saliferous rocks are compared to analogous data available for ionic crystals.

  19. Dynamic Strain Conductivity of Compensated Silicon

    Science.gov (United States)

    Zainabidinov, S. Z.; Mamatkarimov, O. O.; Tursunov, I. G.; Tuychiev, U. A.

    In this paper the strain thermal Hall effect has been investigated in initial n-Si(P) and strongly compensated n-Si(Ni) samples of different compensation degree, which have been subject to uniform hydrostatic compression (UHC) under a pulse pressure regime ranging from 0 to 7×108 Pa. An experimental investigation of the strain thermal effect in the n-Si(Ni) sample leads to an essential strain conductivity increase, which is largely controlled by density variations of majority carriers.

  20. Snowball: Strain aware gene assembly of Metagenomes

    OpenAIRE

    Gregor, I.; Schönhuth, A.; McHardy, A. C.

    2015-01-01

    Gene assembly is an important step in functional analysis of shotgun metagenomic data. Nonetheless, strain aware assembly remains a challenging task, as current assembly tools often fail to distinguish among strain variants or require closely related reference genomes of the studied species to be available. We have developed Snowball, a novel strain aware and reference-free gene assembler for shotgun metagenomic data. It uses profile hidden Markov models (HMMs) of gene domains of interest to ...

  1. Effective heat strain index using pocket computer.

    Science.gov (United States)

    Kamon, E; Ryan, C

    1981-08-01

    An effective heat strain index (EHSI) using a hand calculator with memory is suggested for on-site evaluation of prevailing hot ambient conditions. The inputs to the programmed calculator include dry-bulb, wet-bulb and globe temperatures, and estimates of metabolism and air movements. The index is based on a program for calculation of the total heat balance and on the efficiency of sweating. The display of information on the ambient conditions EHSI display is one of following: no strain; low strain; high strain; or time limits of exposure.

  2. Distributed strain monitoring for bridges: temperature effects

    Science.gov (United States)

    Regier, Ryan; Hoult, Neil A.

    2014-03-01

    To better manage infrastructure assets as they reach the end of their service lives, quantitative data is required to better assess structural behavior and allow for more informed decision making. Distributed fiber optic strain sensors are one sensing technology that could provide comprehensive data for use in structural assessments as these systems potentially allow for strain to be measured with the same accuracy and gage lengths as conventional strain sensors. However, as with many sensor technologies, temperature can play an important role in terms of both the structure's and sensor's performance. To investigate this issue a fiber optic distributed strain sensor system was installed on a section of a two span reinforced concrete bridge on the TransCanada Highway. Strain data was acquired several times a day as well as over the course of several months to explore the effects of changing temperature on the data. The results show that the strain measurements are affected by the bridge behavior as a whole. The strain measurements due to temperature are compared to strain measurements that were taken during a load test on the bridge. The results show that even a small change in temperature can produce crack width and strain changes similar to those due to a fully loaded transport truck. Future directions for research in this area are outlined.

  3. Using strain rates to forecast seismic hazards

    Science.gov (United States)

    Evans, Eileen

    2017-01-01

    One essential component in forecasting seismic hazards is observing the gradual accumulation of tectonic strain accumulation along faults before this strain is suddenly released as earthquakes. Typically, seismic hazard models are based on geologic estimates of slip rates along faults and historical records of seismic activity, neither of which records actively accumulating strain. But this strain can be estimated by geodesy: the precise measurement of tiny position changes of Earth’s surface, obtained from GPS, interferometric synthetic aperture radar (InSAR), or a variety of other instruments.

  4. Differentiation of Listeria and Streptococcus strains.

    Science.gov (United States)

    Herendi, A; Ralovich, B

    1989-01-01

    Colonial morphology of non-beta haemolytic Listeria strains is frequently similar to that of non-haemolytic streptococci. Biochemical characteristics, motility, haemolysis on ox blood agar, growth on Clauberg, selective streptococcus (Si) and Mitis-Salivarius agar medium, CAMP test, serological behaviour of 16 Listeria strains were studied and the results were compared with the properties of Streptococcus strains. Microscopic morphology, motility and catalase activity are useful for distinguishing these strains. To avoid a false diagnosis, latex-agglutination should be supplemented with the above tests.

  5. [Antigenic relationships between Debaryomyces strains (author's transl)].

    Science.gov (United States)

    Aksoycan, N

    1980-01-01

    The results of the agglutinations between homologous and heterologous Debaryomyces strains and their agglutinating sera are shown in table I. According to these findings, D. hansenii and D. marama are antigenically different from other Debaryomyces strains in this genus. In a previous study Aksoycan et al. have shown a common antigenic factor between D. hansenii, D. marama strains and Salmonella 0:7 antigen. This factor was not present in other six strains of Debaryomyces. These results also show that D. tamarii does not have any antigenic relationship with the other seven species of Debaryomyces in this genus.

  6. Measurement of Sorption-Induced Strain

    Energy Technology Data Exchange (ETDEWEB)

    Eric P. Robertson; Richard L. Christiansen

    2005-05-01

    Strain caused by the adsorption of gases was measured in samples of subbituminous coal from the Powder River basin of Wyoming, U.S.A. and high-volatile bituminous coal from east-central Utah, U.S.A. using an apparatus developed jointly at the Idaho National Laboratory (Idaho Falls, Idaho, U.S.A.) and Colorado School of Mines (Golden, Colorado, U.S.A.). The apparatus can be used to measure strain on multiple small coal samples based on the optical detection of the longitudinal strain instead of the more common usage of strain gauges, which require larger samples and longer equilibration times. With this apparatus, we showed that the swelling and shrinkage processes were reversible and that accurate strain data could be obtained in a shortened amount of time. A suite of strain curves was generated for these coals using gases that included carbon dioxide, nitrogen, methane, helium, and various mixtures of these gases. A Langmuir-type equation was applied to satisfactorily model the strain data obtained for pure gases. The sorption-induced strain measured in the subbituminous coal was larger than the high-volatile bituminous coal for all gases tested over the range of pressures used in the experimentation, with the CO2-induced strain for the subbituminous coal over twice as great at the bituminous coal.

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

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Junehyung; Cheon, Jinsik; Lee, Byoungoon; Lee, Chanbock [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-05-15

    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.

  8. True stress-strain curves of cold worked stainless steel over a large range of strains

    Science.gov (United States)

    Kamaya, Masayuki; Kawakubo, Masahiro

    2014-08-01

    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.

  9. Dynamic tensile testing for determining the stress-strain curve at different strain rate

    OpenAIRE

    Mansilla, A; Regidor, A.; García, D.; Negro, A

    2001-01-01

    A detailed discussion of high strain-rate tensile testing is presented. A comparative analysis of different ways to measure stress and strain is made. The experimental stress-strain curves have been suitably interpreted to distinguish between the real behaviour of the material and the influence of the testing methodology itself. A special two sections flat specimen design was performed through FEA computer modelling. The mechanical properties as function of strain rate were experimentally obt...

  10. A Natural Vaccine Candidate Strain Against Cholera

    Institute of Scientific and Technical Information of China (English)

    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.

  11. Job strain and time to pregnancy

    DEFF Research Database (Denmark)

    Hjollund, N H; Jensen, Tina Kold; Bonde, J P

    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....

  12. Surfactin production by strains of Bacillus mojavensis

    Science.gov (United States)

    Bacillus mojavensis, RRC101 is an endophytic bacterium patented for control of fungal diseases in maize and other plants. DNA fingerprint analysis of the rep-PCR fragments of 35 B. mojavensis and 4 B. subtilis strains using the Diversilab genotyping system revealed genotypic distinctive strains alon...

  13. Interactions between Lactobacillus acidophilus strains and the ...

    African Journals Online (AJOL)

    Administrator

    2012-06-26

    Jun 26, 2012 ... Streptococcus thermophilus during fermentation of goats' milk. Su Li, Helen .... culture was propagated weekly in sterile MRS broth with 1% inoculum at 37°C for 24 h, .... recovery ability for relevant strains. For each strain, pure ...

  14. Surface instabilities during straining of anisotropic materials

    DEFF Research Database (Denmark)

    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...

  15. Deformation strain inhomogeneity in columnar grain nickel

    DEFF Research Database (Denmark)

    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...

  16. Strain engineering in graphene by laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Papasimakis, N.; Mailis, S.; Huang, C. C.; Al-Saab, F.; Hewak, D. W. [Optoelectronics Research Centre and Centre for Photonic Metamaterials, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Luo, Z.; Shen, Z. X. [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore)

    2015-02-09

    We demonstrate that the Raman spectrum of graphene on lithium niobate can be controlled locally by continuous exposure to laser irradiation. We interpret our results in terms of changes to doping and mechanical strain and show that our observations are consistent with light-induced gradual strain relaxation in the graphene layer.

  17. Job strain and time to pregnancy

    DEFF Research Database (Denmark)

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

    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....

  18. Marital Role Strain and Sexual Satisfaction.

    Science.gov (United States)

    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)

  19. Snowball: Strain aware gene assembly of Metagenomes

    NARCIS (Netherlands)

    Gregor, I.; Schönhuth, A.; McHardy, A.C.

    2015-01-01

    Gene assembly is an important step in functional analysis of shotgun metagenomic data. Nonetheless, strain aware assembly remains a challenging task, as current assembly tools often fail to distinguish among strain variants or require closely related reference genomes of the studied species to be av

  20. Calculation of the stress-strain stiffness matrix for given strains in an inelastic material

    Energy Technology Data Exchange (ETDEWEB)

    Friedrich, C.M.

    1978-01-01

    In the implicit method of non-linear analysis of stiffness matrices of finite elements, deflection fields and hence strains are assumed known at one stage of the calculations. A procedure is developed to calculate the stress-strain stiffness matrix from the strains without iteration of the stress components when the material is inelastic.

  1. Optimization of tensile strain-hardening cementhious composites for tensile strain capacity

    NARCIS (Netherlands)

    Shionaga, R.; Pansuk, W.; Grunewald, S.; den Uijl, J.A.; Walraven, J.C.

    2014-01-01

    The synergistic action of a cementitious matrix and fibres can result in strain hardening in tension. The accompanied tensile strain capacity can be an important design parameter for strain-hardening cementitious composites in order to prevent the localization in a single crack and to assure that th

  2. Strain localization band width evolution by electronic speckle pattern interferometry strain rate measurement

    Energy Technology Data Exchange (ETDEWEB)

    Guelorget, Bruno [Institut Charles Delaunay-LASMIS, Universite de technologie de Troyes, FRE CNRS 2848, 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France)], E-mail: bruno.guelorget@utt.fr; Francois, Manuel; Montay, Guillaume [Institut Charles Delaunay-LASMIS, Universite de technologie de Troyes, FRE CNRS 2848, 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France)

    2009-04-15

    In this paper, electronic speckle pattern interferometry strain rate measurements are used to quantify the width of the strain localization band, which occurs when a sheet specimen is submitted to tension. It is shown that the width of this band decreases with increasing strain. Just before fracture, this measured width is about five times wider than the shear band and the initial sheet thickness.

  3. General Strain Theory and Delinquency: Focusing on the Influences of Key Strain Characteristics on Delinquency

    Science.gov (United States)

    Moon, Byongook; Blurton, David; McCluskey, John D.

    2008-01-01

    The study examines the effects of recent, older, and chronic strains and of perceived injustice of strain on delinquency, sampling 777 Korean youth. Seven key strains most likely leading to delinquency, some of which were often overlooked in previous research, were included, and these are family conflict, parental punishment, teachers' punishment,…

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

    DEFF Research Database (Denmark)

    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...

  5. Strain rate effects in stress corrosion cracking

    Energy Technology Data Exchange (ETDEWEB)

    Parkins, R.N. (Newcastle upon Tyne Univ. (UK). Dept. of Metallurgy and Engineering Materials)

    1990-03-01

    Slow strain rate testing (SSRT) was initially developed as a rapid, ad hoc laboratory method for assessing the propensity for metals an environments to promote stress corrosion cracking. It is now clear, however, that there are good theoretical reasons why strain rate, as opposed to stress per se, will often be the controlling parameter in determining whether or not cracks are nucleated and, if so, are propagated. The synergistic effects of the time dependence of corrosion-related reactions and microplastic strain provide the basis for mechanistic understanding of stress corrosion cracking in high-pressure pipelines and other structures. However, while this may be readily comprehended in the context of laboratory slow strain tests, its extension to service situations may be less apparent. Laboratory work involving realistic stressing conditions, including low-frequency cyclic loading, shows that strain or creep rates give good correlation with thresholds for cracking and with crack growth kinetics.

  6. Review of graphene-based strain sensors

    Institute of Scientific and Technical Information of China (English)

    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.

  7. Pseudomagnetic fields and triaxial strain in graphene

    DEFF Research Database (Denmark)

    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....

  8. On lower order strain gradient plasticity theories

    DEFF Research Database (Denmark)

    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 t...... the tangential moduli governing increments of stress and strain. It is shown that the modification is far from benign from a mathematical standpoint, changing the qualitative character of solutions and leading to a new type of localization that appears to be unphysical.......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...

  9. Atlas of stress-strain curves

    CERN Document Server

    2002-01-01

    The Atlas of Stress-Strain Curves, Second Edition is substantially bigger in page dimensions, number of pages, and total number of curves than the previous edition. It contains over 1,400 curves, almost three times as many as in the 1987 edition. The curves are normalized in appearance to aid making comparisons among materials. All diagrams include metric (SI) units, and many also include U.S. customary units. All curves are captioned in a consistent format with valuable information including (as available) standard designation, the primary source of the curve, mechanical properties (including hardening exponent and strength coefficient), condition of sample, strain rate, test temperature, and alloy composition. Curve types include monotonic and cyclic stress-strain, isochronous stress-strain, and tangent modulus. Curves are logically arranged and indexed for fast retrieval of information. The book also includes an introduction that provides background information on methods of stress-strain determination, on...

  10. Dark field electron holography for strain measurement

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. The Effect of Ivermectin in Seven Strains of Aedes aegypti (Diptera: Culicidae) Including a Genetically Diverse Laboratory Strain and Three Permethrin Resistant Strains

    OpenAIRE

    Deus, K. M.; Saavedra-rodriguez, K.; Butters, M. P.; Black, W C; Foy, B.D.

    2012-01-01

    Seven different strains of Aedes aegypti (L.), including a genetically diverse laboratory strain, three laboratory-selected permethrin-resistant strains, a standard reference strain, and two recently colonized strains were fed on human blood containing various concentrations of ivermectin. Ivermectin reduced adult survival, fecundity, and hatch rate of eggs laid by ivermectin-treated adults in all seven strains. The LC50 of ivermectin for adults and the concentration that prevented 50% of egg...

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

    CERN Document Server

    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.

  13. Amerindian Helicobacter pylori strains go extinct, as european strains expand their host range.

    Directory of Open Access Journals (Sweden)

    Maria G Domínguez-Bello

    Full Text Available We studied the diversity of bacteria and host in the H. pylori-human model. The human indigenous bacterium H. pylori diverged along with humans, into African, European, Asian and Amerindian groups. Of these, Amerindians have the least genetic diversity. Since niche diversity widens the sets of resources for colonizing species, we predicted that the Amerindian H. pylori strains would be the least diverse. We analyzed the multilocus sequence (7 housekeeping genes of 131 strains: 19 cultured from Africans, 36 from Spanish, 11 from Koreans, 43 from Amerindians and 22 from South American Mestizos. We found that all strains that had been cultured from Africans were African strains (hpAfrica1, all from Spanish were European (hpEurope and all from Koreans were hspEAsia but that Amerindians and Mestizos carried mixed strains: hspAmerind and hpEurope strains had been cultured from Amerindians and hpEurope and hpAfrica1 were cultured from Mestizos. The least genetically diverse H. pylori strains were hspAmerind. Strains hpEurope were the most diverse and showed remarkable multilocus sequence mosaicism (indicating recombination. The lower genetic structure in hpEurope strains is consistent with colonization of a diversity of hosts. If diversity is important for the success of H. pylori, then the low diversity of Amerindian strains might be linked to their apparent tendency to disappear. This suggests that Amerindian strains may lack the needed diversity to survive the diversity brought by non-Amerindian hosts.

  14. Strain hardening rate sensitivity and strain rate sensitivity in TWIP steels

    Energy Technology Data Exchange (ETDEWEB)

    Bintu, Alexandra [TEMA, Department of Mechanical Engineering, University of Aveiro, Campus Universitário de Santiago, 3810-193 (Portugal); Vincze, Gabriela, E-mail: gvincze@ua.pt [TEMA, Department of Mechanical Engineering, University of Aveiro, Campus Universitário de Santiago, 3810-193 (Portugal); Picu, Catalin R. [Department of Mechanical, Aerospace and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 (United States); Lopes, Augusto B. [CICECO, Department of Materials and Ceramic Engineering, University of Aveiro, Campus Universitário de Santiago, 3810-193 (Portugal); Grácio, Jose J. [TEMA, Department of Mechanical Engineering, University of Aveiro, Campus Universitário de Santiago, 3810-193 (Portugal); Barlat, Frederic [Materials Mechanics Laboratory, Graduate Institute of Ferrous Technology, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

    2015-04-01

    TWIP steels are materials with very high strength and exceptional strain hardening capability, parameters leading to large energy absorption before failure. However, TWIP steels also exhibit reduced (often negative) strain rate sensitivity (SRS) which limits the post-necking deformation. In this study we demonstrate for an austenitic TWIP steel with 18% Mn a strong dependence of the twinning rate on the strain rate, which results in negative strain hardening rate sensitivity (SHRS). The instantaneous component of SHRS is large and negative, while its transient is close to zero. The SRS is observed to decrease with strain, becoming negative for larger strains. Direct observations of the strain rate dependence of the twinning rate are made using electron microscopy and electron backscatter diffraction, which substantiate the proposed mechanism for the observed negative SHRS.

  15. Anisotropic strain enhanced hydrogen solubility in bcc metals: the independence on the sign of strain.

    Science.gov (United States)

    Zhou, Hong-Bo; Jin, Shuo; Zhang, Ying; Lu, Guang-Hong; Liu, Feng

    2012-09-28

    When an impurity is doped in a solid, it inevitably induces a local stress, tending to expand or contract the lattice. Consequently, strain can be applied to change the solubility of impurity in a solid. Generally, the solubility responds to strain "monotonically," increasing (decreasing) with the tensile (compressive) strain if the impurity induces a compressive stress or vice versa. Using first-principles calculations, however, we discovered that the H solubility can be enhanced by anisotropic strain in some bcc metals, almost independent of the sign of strain. This anomalous behavior is found to be caused by a continuous change of H location induced by anisotropic strain. Our finding suggests a cascading effect of H bubble formation in bcc metals: the H solution leads to H bubble formation that induces anisotropic strain that in turn enhances H solubility to further facilitate bubble growth.

  16. On fracture in finite strain gradient plasticity

    DEFF Research Database (Denmark)

    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 invest......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...

  17. Specific identification of Bacillus anthracis strains

    Science.gov (United States)

    Krishnamurthy, Thaiya; Deshpande, Samir; Hewel, Johannes; Liu, Hongbin; Wick, Charles H.; Yates, John R., III

    2007-01-01

    Accurate identification of human pathogens is the initial vital step in treating the civilian terrorism victims and military personnel afflicted in biological threat situations. We have applied a powerful multi-dimensional protein identification technology (MudPIT) along with newly generated software termed Profiler to identify the sequences of specific proteins observed for few strains of Bacillus anthracis, a human pathogen. Software termed Profiler was created to initially screen the MudPIT data of B. anthracis strains and establish the observed proteins specific for its strains. A database was also generated using Profiler containing marker proteins of B. anthracis and its strains, which in turn could be used for detecting the organism and its corresponding strains in samples. Analysis of the unknowns by our methodology, combining MudPIT and Profiler, led to the accurate identification of the anthracis strains present in samples. Thus, a new approach for the identification of B. anthracis strains in unknown samples, based on the molecular mass and sequences of marker proteins, has been ascertained.

  18. Heterogeneity of inelastic strain during creep of Carrara marble: Microscale strain measurement technique

    Science.gov (United States)

    Quintanilla-Terminel, Alejandra; Evans, Brian

    2016-08-01

    We combined the split cylinder technique with microfabrication technology to observe strain heterogeneities that were produced during high-pressure transient creep of Carrara marble. Samples were patterned with a custom-designed grid of markers spaced 10 µm apart and containing an embedded coordinate system. The microscale strain measurement (MSSM) technique described here allowed us to analyze the local strain distribution with unprecedented detail over large regions. The description of the strain field is a function of the area over which strain is being computed. The scale at which the strain field can be considered homogeneous can provide insight into the deformation processes taking place. At 400-500°C, when twinning production is prolific, we observe highly strained bands that span several grains. One possible cause for the multigrain bands is the need to relieve strain incompatibilities that result when twins impinge on neighboring grains. At 600-700°C, the strain fields are still quite heterogeneous, and local strain varies substantially within grains and near grain boundaries, but the multigrain slip bands are not present. Deformation is concentrated in much smaller areas within grains and along some grain boundaries. The disappearance of the multigrain slip bands occurs when the deformation conditions allow additional slip systems to be activated. At 600°C, when the total strain is varied from 0.11 to 0.36, the spatial scale of the heterogeneity does not vary, but there are increases in the standard deviation of the distribution of local strains normalized by the total strain; thus, we conclude that the microstructure does not achieve a steady state in this strain interval.

  19. Highly Invasive Listeria monocytogenes Strains Have Growth and Invasion Advantages in Strain Competition.

    Science.gov (United States)

    Zilelidou, Evangelia A; Rychli, Kathrin; Manthou, Evanthia; Ciolacu, Luminita; Wagner, Martin; Skandamis, Panagiotis N

    2015-01-01

    Multiple Listeria monocytogenes strains can be present in the same food sample; moreover, infection with more than one L. monocytogenes strain can also occur. In this study we investigated the impact of strain competition on the growth and in vitro virulence potential of L. monocytogenes. We identified two strong competitor strains, whose growth was not (or only slightly) influenced by the presence of other strains and two weak competitor strains, which were outcompeted by other strains. Cell contact was essential for growth inhibition. In vitro virulence assays using human intestinal epithelial Caco2 cells showed a correlation between the invasion efficiency and growth inhibition: the strong growth competitor strains showed high invasiveness. Moreover, invasion efficiency of the highly invasive strain was further increased in certain combinations by the presence of a low invasive strain. In all tested combinations, the less invasive strain was outcompeted by the higher invasive strain. Studying the effect of cell contact on in vitro virulence competition revealed a complex pattern in which the observed effects depended only partially on cell-contact suggesting that competition occurs at two different levels: i) during co-cultivation prior to infection, which might influence the expression of virulence factors, and ii) during infection, when bacterial cells compete for the host cell. In conclusion, we show that growth of L. monocytogenes can be inhibited by strains of the same species leading potentially to biased recovery during enrichment procedures. Furthermore, the presence of more than one L. monocytogenes strain in food can lead to increased infection rates due to synergistic effects on the virulence potential.

  20. Stability of germanene under tensile strain

    KAUST Repository

    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.

  1. Semiconductor strain metrology principles and applications

    CERN Document Server

    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

  2. Strain gradient effects in surface roughening

    DEFF Research Database (Denmark)

    Borg, Ulrik; Fleck, N.A.

    2007-01-01

    A thin aluminium sheet comprising of large polycrystals is pulled in uniaxial tension and the resulting surface profile is measured in a scanning electron microscope. The surface profile near the grain boundaries reveals a local deformation pattern of width of a few micrometres and is strong...... evidence for strain gradient effects. Numerical analyses of a bicrystal undergoing in-plane tensile deformation are also studied using a strain gradient crystal plasticity theory and also by using a strain gradient plasticity theory for an isotropic solid. Both theories include an internal material length...

  3. Biological characterization of Trypanosoma cruzi strains

    Directory of Open Access Journals (Sweden)

    Rafael A Martínez-Díaz

    2001-01-01

    Full Text Available Biological parameters of five Trypanosoma cruzi strains from different sources were determined in order to know the laboratory behaviour of natural populations. The parameters evaluated were growth kinetics of epimastigotes, differentiation into metacyclic forms, infectivity in mammalian cells grown in vitro and parasite susceptibility to nifurtimox, benznidazole and gentian violet. Differences in transformation to metacyclic, in the percentage of infected cells as well as in the number of amastigotes per cell were observed among the strains. Regarding to pharmacological assays, Y strain was the most sensitive to the three assayed compounds. These data demonstrate the heterogeneity of natural populations of T. cruzi, the only responsible of infection in humans.

  4. Ductile Damage Evolution and Strain Path Dependency

    Science.gov (United States)

    Tasan, C. C.; Hoefnagels, J. M. P.; Peerlings, R. H. J.; Geers, M. G. D.; ten Horn, C. H. L. J.; Vegter, H.

    2007-04-01

    Forming limit diagrams are commonly used in sheet metal industry to define the safe forming regions. These diagrams are built to define the necking strains of sheet metals. However, with the rise in the popularity of advance high strength steels, ductile fracture through damage evolution has also emerged as an important parameter in the determination of limit strains. In this work, damage evolution in two different steels used in the automotive industry is examined to observe the relationship between damage evolution and the strain path that is followed during the forming operation.

  5. STRAIN ANALYSIS OF LATERAL EXTRUSION PROCESS

    Institute of Scientific and Technical Information of China (English)

    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.

  6. Differentiation of pathogenic and saprophytic leptospira strains.

    Science.gov (United States)

    Bazovská, S; Kmety, E; Rak, J

    1984-09-01

    Comparative studies of 249 pathogenic and 80 saprophytic leptospira strains, including 2 strains of the illini type, using the 8-azaguanine test, growth at 13 degrees C and growth on trypticase soy broth revealed their good differentiating potency if the recommended conditions were carefully observed. The same results were obtained by a simple hemolytic test using sheep and rat blood cells, having the advantage of providing results within 24 h. This test is suggested to replace the 8-azaguanine and the growth test at 13 degrees C. In these investigations, the first European strain of the illini type was recognized.

  7. Rat Strain Ontology: structured controlled vocabulary designed to facilitate access to strain data at RGD.

    Science.gov (United States)

    Nigam, Rajni; Munzenmaier, Diane H; Worthey, Elizabeth A; Dwinell, Melinda R; Shimoyama, Mary; Jacob, Howard J

    2013-11-22

    The Rat Genome Database (RGD) ( http://rgd.mcw.edu/) is the premier site for comprehensive data on the different strains of the laboratory rat (Rattus norvegicus). The strain data are collected from various publications, direct submissions from individual researchers, and rat providers worldwide. Rat strain, substrain designation and nomenclature follow the Guidelines for Nomenclature of Mouse and Rat Strains, instituted by the International Committee on Standardized Genetic Nomenclature for Mice. While symbols and names aid in identifying strains correctly, the flat nature of this information prohibits easy search and retrieval, as well as other data mining functions. In order to improve these functionalities, particularly in ontology-based tools, the Rat Strain Ontology (RS) was developed. The Rat Strain Ontology (RS) reflects the breeding history, parental background, and genetic manipulation of rat strains. This controlled vocabulary organizes strains by type: inbred, outbred, chromosome altered, congenic, mutant and so on. In addition, under the chromosome altered category, strains are organized by chromosome, and further by type of manipulations, such as mutant or congenic. This allows users to easily retrieve strains of interest with modifications in specific genomic regions. The ontology was developed using the Open Biological and Biomedical Ontology (OBO) file format, and is organized on the Directed Acyclic Graph (DAG) structure. Rat Strain Ontology IDs are included as part of the strain report (RS: ######). As rat researchers are often unaware of the number of substrains or altered strains within a breeding line, this vocabulary now provides an easy way to retrieve all substrains and accompanying information. Its usefulness is particularly evident in tools such as the PhenoMiner at RGD, where users can now easily retrieve phenotype measurement data for related strains, strains with similar backgrounds or those with similar introgressed regions. This

  8. Characterization and monitoring of selected rhizobial strains ...

    African Journals Online (AJOL)

    SERVER

    2007-06-18

    Jun 18, 2007 ... The nodule occupancy of selected strains in forest soil condition was investigated by ... Colony form-ing was observed every day ..... gram of nodA PCR- product analysis (Figure 1) show- ..... Phylogeny of root and stem-.

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

    Science.gov (United States)

    ... Feeding Your 1- to 2-Year-Old 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 ...

  10. Energy Harvesting Wireless Strain Networks Project

    Data.gov (United States)

    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...

  11. Aerosol printed carbon nanotube strain sensor

    Science.gov (United States)

    Thompson, Bradley; Yoon, Hwan-Sik

    2012-04-01

    In recent years, printed electronics have received attention as a method to produce low-cost macro electronics on flexible substrates. In this regard, inkjet and aerosol printing have been the primary printing methods for producing passive electrical components, transistors, and a number of sensors. In this research, a custom aerosol printer was utilized to create a strain sensor capable of measuring static and dynamic strain. The proposed sensor was created by aerosol printing a multiwall carbon nanotube solution onto an aluminum beam covered with an insulating layer. After printing the carbon nanotube-based sensor, the sensor was tested under quasi-static and vibration strain conditions, and the results are presented. The results show that the printed sensor could potentially serve as an effective method for measuring dynamic strain of structural components.

  12. Job strain and the risk of stroke

    DEFF Research Database (Denmark)

    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....... CONCLUSION: Job strain may be associated with an increased risk of ischemic stroke, but further research is needed to determine whether interventions targeting job strain would reduce stroke risk beyond existing preventive strategies....

  13. Screening of Trichoderma strains tolerant to benzimidazole

    Institute of Scientific and Technical Information of China (English)

    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.

  14. 3D Morphing Using Strain Field Interpolation

    Institute of Scientific and Technical Information of China (English)

    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.

  15. Five challenges in modelling interacting strain dynamics

    DEFF Research Database (Denmark)

    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 immunity...

  16. Hospital strain colonization by Staphylococcus epidermidis

    Directory of Open Access Journals (Sweden)

    D. Blum-Menezes

    2009-03-01

    Full Text Available The skin and mucous membranes of healthy subjects are colonized by strains of Staphylococcus epidermidis showing a high diversity of genomic DNA polymorphisms. Prolonged hospitalization and the use of invasive procedures promote changes in the microbiota with subsequent colonization by hospital strains. We report here a patient with prolonged hospitalization due to chronic pancreatitis who was treated with multiple antibiotics, invasive procedures and abdominal surgery. We studied the dynamics of skin colonization by S. epidermidis leading to the development of catheter-related infections and compared the genotypic profile of clinical and microbiota strains by pulsed field gel electrophoresis. During hospitalization, the normal S. epidermidis skin microbiota exhibiting a polymorphic genomic DNA profile was replaced with a hospital-acquired biofilm-producer S. epidermidis strain that subsequently caused repetitive catheter-related infections.

  17. Feline Origin of Rotavirus Strain, Tunisia, 2008

    Science.gov (United States)

    Fredj, Mouna Ben Hadj; Heylen, Elisabeth; Zeller, Mark; Fodha, Imene; Benhamida-Rebai, Meriam; Van Ranst, Marc; Matthijnssens, Jelle

    2013-01-01

    In Tunisia in 2008, an unusual G6P[9] rotavirus, RVA/human-wt/TUN/17237/2008/G6P[9], rarely found in humans, was detected in a child. To determine the origin of this strain, we conducted phylogenetic analyses and found a unique genotype constellation resembling rotaviruses belonging to the feline BA222-like genotype constellation. The strain probably resulted from direct cat-to-human transmission. PMID:23631866

  18. NEW STRAIN GRADIENT THEORY AND ANALYSIS

    Institute of Scientific and Technical Information of China (English)

    Dake Yi; Tzu Chiang Wang; Shaohua Chen

    2009-01-01

    A new strain gradient theory which is based on energy nonlocal model is proposed in this paper, and the theory is applied to investigate the size effects in thin metallic wire torsion, ultra-thin beam bending and micro-indentation of polycrystalline copper. First, an energy nonlocal model is suggested. Second, based on the model, a new strain gradient theory is derived. Third, the new theory is applied to analyze three representative experiments.

  19. Digital Eye Strain Reduction Techniques: A Review

    OpenAIRE

    PREETHI J SEEGEHALLI

    2016-01-01

    Digital eye strain or computer vision syndrome (CVS) is caused when we spend considerable amount of time in staring at digital screens of desktop computer, laptop, e-readers, tablets and mobile phones. This paper discusses the different the causes for visual fatigue and digital eye strain reduction techniques like usage of optical glass, flicker free screen, color filtering, fuzzy logic based brightness adaption technique, bias lighting screens, optimizing monitor’s color temperature and Auto...

  20. A high-strain-rate superplastic ceramic.

    Science.gov (United States)

    Kim, B N; Hiraga, K; Morita, K; Sakka, Y

    2001-09-20

    High-strain-rate superplasticity describes the ability of a material to sustain large plastic deformation in tension at high strain rates of the order of 10-2 to 10-1 s-1 and is of great technological interest for the shape-forming of engineering materials. High-strain-rate superplasticity has been observed in aluminium-based and magnesium-based alloys. But for ceramic materials, superplastic deformation has been restricted to low strain rates of the order of 10-5 to 10-4 s-1 for most oxides and nitrides with the presence of intergranular cavities leading to premature failure. Here we show that a composite ceramic material consisting of tetragonal zirconium oxide, magnesium aluminate spinel and alpha-alumina phases exhibits superplasticity at strain rates up to 1 s-1. The composite also exhibits a large tensile elongation, exceeding 1,050 per cent for a strain rate of 0.4 s-1. The tensile flow behaviour and deformed microstructure of the material indicate that superplasticity is due to a combination of limited grain growth in the constitutive phases and the intervention of dislocation-induced plasticity in the zirconium oxide phase. We suggest that the present results hold promise for the application of shape-forming technologies to ceramic materials.

  1. Strain mapping in a graphene monolayer nanocomposite.

    Science.gov (United States)

    Young, Robert J; Gong, Lei; Kinloch, Ian A; Riaz, Ibtsam; Jalil, Rashed; Novoselov, Kostya S

    2011-04-26

    Model composite specimens have been prepared consisting of a graphene monolayer sandwiched between two thin layers of polymer on the surface of a poly(methyl methacrylate) beam. It has been found that well-defined Raman spectra can be obtained from the single graphene atomic layer and that stress-induced Raman band shifts enable the strain distribution in the monolayer to be mapped with a high degree of precision. It has been demonstrated that the distribution of strain across the graphene monolayer is relatively uniform at levels of applied strain up to 0.6% but that it becomes highly nonuniform above this strain. The change in the strain distributions has been shown to be due to a fragmentation process due to the development of cracks, most likely in the polymer coating layers, with the graphene remaining intact. The strain distributions in the graphene between the cracks are approximately triangular in shape, and the interfacial shear stress in the fragments is only about 0.25 MPa, which is an order of magnitude lower than the interfacial shear stress before fragmentation. This relatively poor level of adhesion between the graphene and polymer layers has important implications for the use of graphene in nanocomposites, and methods of strengthening the graphene-polymer interface are discussed.

  2. Strain rate measurement by Electronic Speckle Pattern Interferometry: A new look at the strain localization onset

    Energy Technology Data Exchange (ETDEWEB)

    Guelorget, Bruno [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France)]. E-mail: bruno.guelorget@utt.fr; Francois, Manuel [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France); Vial-Edwards, Cristian [Departemento de Ingenieria Mecanica y Metalurgica, Pontificia Universidad Catolica de Chile, Vicuna Mackenna 4860, 6904411 Santiago (Chile); Montay, Guillaume [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France); Daniel, Laurent [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France); Lu, Jian [Universite de Technologie de Troyes (UTT), Laboratoire des Systemes Mecaniques et d' ingenierie Simultanee (LASMIS, CNRS FRE 2719), 12 rue Marie Curie, B.P. 2060, 10010 Troyes Cedex (France)

    2006-01-15

    In-plane Electronic Speckle Pattern Interferometry has been successfully used during tensile testing of semi-hard copper sheets in order to measure the strain rate. On one hand, heterogeneity in strain rate field has been found before the maximum of the tensile force ({epsilon} {sup t} {approx_equal} 19.4 and 25.4%, respectively). Thus, a localization phenomenon occurs before the classic Considere's criterion (dF = 0) for the diffuse neck initiation. On the other hand, strain rate measurement before fracture shows the moment where one of the two slip band systems becomes predominant, then strain concentrates in a small area, the shear band. Uncertainty evaluation has been carried out, which shows a very good accuracy of the total strain and the strain rate measurements.

  3. Purification of Helicobacter suis Strains From Biphasic Cultures by Single Colony Isolation: Influence on Strain Characteristics.

    Science.gov (United States)

    Liang, Jungang; De Bruyne, Ellen; Ducatelle, Richard; Smet, Annemieke; Haesebrouck, Freddy; Flahou, Bram

    2015-06-01

    Helicobacter (H.) suis causes gastritis and decreased weight gain in pigs. It is also the most prevalent non-Helicobacter pylori Helicobacter species in humans with gastric disease. H. suis is extremely fastidious, and so far, biphasic culture conditions were essential for isolation and culture, making it impossible to obtain single colonies. Hence, cultures obtained from an individual animal may contain multiple H. suis strains, which is undesirable for experiments aiming for instance at investigating H. suis strain differences. Pure cultures of H. suis were established by growing bacteria as colonies on 1% brucella agar plates, followed by purification and enrichment by biphasic subculture. Characteristics of these single colony-derived strains were compared with those of their parent strains using multilocus sequence typing (MLST) and by studying bacterium-host interactions using a gastric epithelial cell line and Mongolian gerbil model. The purification/enrichment procedure required a nonstop culture of several weeks. For 4 of 17 H. suis strains, MLST revealed differences between parental and single colony-derived strains. For three of four single colony-derived strains tested, the cell death-inducing capacity was higher than for the parental strain. One single colony-derived strain lost its capacity to colonize Mongolian gerbils. For the four other strains tested, colonization capacity and histopathologic changes were similar to what has been described when using strains with only a history of limited biphasic culture. A method was developed to obtain single colony-derived H. suis strains, but this procedure may affect the bacterial genotype and phenotype. © 2015 John Wiley & Sons Ltd.

  4. Intramyocardial strain estimation from cardiac cine MRI.

    Science.gov (United States)

    Elnakib, Ahmed; Beache, Garth M; Gimel'farb, Georgy; El-Baz, Ayman

    2015-08-01

    Functional strain is one of the important clinical indicators for the quantification of heart performance and the early detection of cardiovascular diseases, and functional strain parameters are used to aid therapeutic decisions and follow-up evaluations after cardiac surgery. A comprehensive framework for deriving functional strain parameters at the endocardium, epicardium, and mid-wall of the left ventricle (LV) from conventional cine MRI data was developed and tested. Cine data were collected using short TR-/TE-balanced steady-state free precession acquisitions on a 1.5T Siemens Espree scanner. The LV wall borders are segmented using a level set-based deformable model guided by a stochastic force derived from a second-order Markov-Gibbs random field model that accounts for the object shape and appearance features. Then, the mid-wall of the segmented LV is determined based on estimating the centerline between the endocardium and epicardium of the LV. Finally, a geometrical Laplace-based method is proposed to track corresponding points on successive myocardial contours throughout the cardiac cycle in order to characterize the strain evolutions. The method was tested using simulated phantom images with predefined point locations of the LV wall throughout the cardiac cycle. The method was tested on 30 in vivo datasets to evaluate the feasibility of the proposed framework to index functional strain parameters. The cine MRI-based model agreed with the ground truth for functional metrics to within 0.30 % for indexing the peak systolic strain change and 0.29 % (per unit time) for indexing systolic and diastolic strain rates. The method was feasible for in vivo extraction of functional strain parameters. Strain indexes of the endocardium, mid-wall, and epicardium can be derived from routine cine images using automated techniques, thereby improving the utility of cine MRI data for characterization of myocardial function. Unlike traditional texture-based tracking, the

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  6. On the use of strain sensor technologies for strain modal analysis: Case studies in aeronautical applications

    Science.gov (United States)

    Marques dos Santos, Fábio Luis; Peeters, Bart

    2016-10-01

    This paper discusses the use of optical fiber Bragg grating (FBG) and piezo strain sensors for structural dynamic measurements. For certain industrial applications, there is an interest to use strain sensors rather than in combination with accelerometers for experimental modal analysis. Classical electrical strain gauges can be used hereto, but other types of strain sensors are an interesting alternative with some very specific advantages. This work gives an overview of two types of dynamic strain sensors, applied to two industrial applications (a helicopter main rotor blade and an F-16 aircraft), FBG sensors and dynamic piezo strain sensors, discussing their use and benefits. Moreover, the concept of strain modal analysis is introduced and it is shown how it can be beneficial to apply strain measurements to experimental modal analysis. Finally, experimental results for the two applications are shown, with an experimental modal analysis carried out on the helicopter main rotor blade using FBG sensors and a similar experiment is done with the aircraft but using piezo strain sensors instead.

  7. True stress–strain curve acquisition for irradiated stainless steel including the range exceeding necking strain

    Energy Technology Data Exchange (ETDEWEB)

    Kamaya, Masayuki, E-mail: kamaya@inss.co.jp [Institute of Nuclear Safety System, Inc., 64 Sata Mihama-cho, Fukui 919-1205 (Japan); Kitsunai, Yuji; Koshiishi, Masato [Nippon Nuclear Fuel Dvelopment Co., Ltd., 2163 Narita-cho, Oarai-machi, Ibaraki 311-1313 (Japan)

    2015-10-15

    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.

  8. A numerical method for determining the strain rate intensity factor under plane strain conditions

    Science.gov (United States)

    Alexandrov, S.; Kuo, C.-Y.; Jeng, Y.-R.

    2016-07-01

    Using the classical model of rigid perfectly plastic solids, the strain rate intensity factor has been previously introduced as the coefficient of the leading singular term in a series expansion of the equivalent strain rate in the vicinity of maximum friction surfaces. Since then, many strain rate intensity factors have been determined by means of analytical and semi-analytical solutions. However, no attempt has been made to develop a numerical method for calculating the strain rate intensity factor. This paper presents such a method for planar flow. The method is based on the theory of characteristics. First, the strain rate intensity factor is derived in characteristic coordinates. Then, a standard numerical slip-line technique is supplemented with a procedure to calculate the strain rate intensity factor. The distribution of the strain rate intensity factor along the friction surface in compression of a layer between two parallel plates is determined. A high accuracy of this numerical solution for the strain rate intensity factor is confirmed by comparison with an analytic solution. It is shown that the distribution of the strain rate intensity factor is in general discontinuous.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Marvin Schmidt

    2016-06-01

    Full Text Available 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.

  11. Two strains of Crocosphaera watsonii with highly conserved genomes are distinguished by strain-specific features

    Directory of Open Access Journals (Sweden)

    Shellie Roxanne Bench

    2011-12-01

    Full Text Available Unicellular nitrogen-fixing cyanobacteria are important components of marine phytoplankton. Although non-nitrogen-fixing marine phytoplankton generally exhibit high gene sequence and genomic diversity, gene sequences of natural populations and isolated strains of Crocosphaera watsonii, one of two most abundant open ocean unicellular cyanobacteria groups, have been shown to be 98-100% identical.. The low sequence diversity in Crocosphaera is a dramatic contrast to sympatric species of Prochlorococcus and Synechococcus, and raises the question of how genome differences can explain observed phenotypic diversity among Crocosphaera strains. Here we show, through whole genome comparisons of two phenotypically different strains, that there are strain-specific sequences in each genome, and numerous genome rearrangements, despite exceptionally low sequence diversity in shared genomic regions. Some of the strain-specific sequences encode functions that explain observed phenotypic differences, such as exopolysaccharide biosynthesis. The pattern of strain-specific sequences distributed throughout the genomes, along with rearrangements in shared sequences is evidence of significant genetic mobility that may be attributed to the hundreds of transposase genes found in both strains. Furthermore, such genetic mobility appears to be the main mechanism of strain divergence in Crocosphaera which do not accumulate DNA microheterogeneity over the vast majority of their genomes. The strain-specific sequences found in this study provide tools for future physiological studies, as well as genetic markers to help determine the relative abundance of phenotypes in natural populations.

  12. Dynamic strains for earthquake source characterization

    Science.gov (United States)

    Barbour, Andrew J.; Crowell, Brendan W

    2017-01-01

    Strainmeters measure elastodynamic deformation associated with earthquakes over a broad frequency band, with detection characteristics that complement traditional instrumentation, but they are commonly used to study slow transient deformation along active faults and at subduction zones, for example. Here, we analyze dynamic strains at Plate Boundary Observatory (PBO) borehole strainmeters (BSM) associated with 146 local and regional earthquakes from 2004–2014, with magnitudes from M 4.5 to 7.2. We find that peak values in seismic strain can be predicted from a general regression against distance and magnitude, with improvements in accuracy gained by accounting for biases associated with site–station effects and source–path effects, the latter exhibiting the strongest influence on the regression coefficients. To account for the influence of these biases in a general way, we include crustal‐type classifications from the CRUST1.0 global velocity model, which demonstrates that high‐frequency strain data from the PBO BSM network carry information on crustal structure and fault mechanics: earthquakes nucleating offshore on the Blanco fracture zone, for example, generate consistently lower dynamic strains than earthquakes around the Sierra Nevada microplate and in the Salton trough. Finally, we test our dynamic strain prediction equations on the 2011 M 9 Tohoku‐Oki earthquake, specifically continuous strain records derived from triangulation of 137 high‐rate Global Navigation Satellite System Earth Observation Network stations in Japan. Moment magnitudes inferred from these data and the strain model are in agreement when Global Positioning System subnetworks are unaffected by spatial aliasing.

  13. Volume strain within the Geysers geothermal field

    Energy Technology Data Exchange (ETDEWEB)

    Mossop, Antony [Department of Geophysics, Stanford University, Stanford, California (United States); Segall, Paul [Department of Geophysics, Stanford University, Stanford, California (United States)

    1999-12-10

    During the 1970s and 1980s. The Geysers geothermal region was rapidly developed as a site of geothermal power production. The likelihood that this could cause significant strain within the reservoir, with corresponding surface displacements, led to a series of deformation monitoring surveys. In 1973, 1975, 1977, and 1980, The Geysers region was surveyed using first-order, class I, spirit leveling. In 1994, 1995, and 1996, many of the leveling control monuments were resurveyed using high-precision Global Positioning System receivers. The two survey methods are reconciled using the GEOID96 geoid model. The displacements are inverted to determine volume strain within the reservoir. For the period 1980-1994, peak volume strains in excess of 5x10{sup -4} are imaged. There is an excellent correlation between the observed changes in reservoir steam pressures and the imaged volume strain. If reservoir pressure changes are inducing volume strain, then the reservoir quasi-static bulk modulus K must be <4.6x10{sup 9} Pa. However, seismic velocities indicate a much stiffer reservoir with K=3.4x10{sup 10} Pa. This apparent discrepancy is shown to be consistent with predicted frequency dependence in K for fractured and water-saturated rock. Inversion of surface deformation data therefore appears to be a powerful method for imaging pressure change within the body of the reservoir. Correlation between induced seismicity at The Geysers and volume strain is observed. However, earthquake distribution does not appear to have a simple relationship with volume strain rate. (c) 1999 American Geophysical Union.

  14. Tensile Strain Hardening Behavior and Fractography of Superalloy GH39

    Directory of Open Access Journals (Sweden)

    WANG Hui

    2016-10-01

    Full Text Available The strain hardening behaviour and fractography of superalloy GH39 was investigated by tensile test at different strain rates. Results indicate that strain hardening behaviours are different during the deformation process. True stress-strain curve obeys the Hollomon relationship partly. The strain hardening exponentn in this stage is constant in the initial plastic stage. However, the value of n increased with true strain ε increasing when true strain is between 0.014 and 0.13. A lot of deformation twinning can be found, the twins and dislocations worked together to increase the value of n. The strain hardening exponent is increased lightly with the strain rate increasing, SEM observations show that in the case of low strain rate, the fracture mode is typical ductile, but there is a tendency from ductile to brittle fracture with increasing the strain rate.

  15. Mycobacterium tuberculosis strains exhibit differential and strain-specific molecular signatures in pulmonary epithelial cells.

    Science.gov (United States)

    Mvubu, Nontobeko Eunice; Pillay, Balakrishna; Gamieldien, Junaid; Bishai, William; Pillay, Manormoney

    2016-12-01

    Although pulmonary epithelial cells are integral to innate and adaptive immune responses during Mycobacterium tuberculosis infection, global transcriptomic changes in these cells remain largely unknown. Changes in gene expression induced in pulmonary epithelial cells infected with M. tuberculosis F15/LAM4/KZN, F11, F28, Beijing and Unique genotypes were investigated by RNA sequencing (RNA-Seq). The Illumina HiSeq 2000 platform generated 50 bp reads that were mapped to the human genome (Hg19) using Tophat (2.0.10). Differential gene expression induced by the different strains in infected relative to the uninfected cells was quantified and compared using Cufflinks (2.1.0) and MeV (4.0.9), respectively. Gene expression varied among the strains with the total number of genes as follows: F15/LAM4/KZN (1187), Beijing (1252), F11 (1639), F28 (870), Unique (886) and H37Rv (1179). A subset of 292 genes was commonly induced by all strains, where 52 genes were down-regulated while 240 genes were up-regulated. Differentially expressed genes were compared among the strains and the number of induced strain-specific gene signatures were as follows: F15/LAM4/KZN (138), Beijing (52), F11 (255), F28 (55), Unique (186) and H37Rv (125). Strain-specific molecular gene signatures associated with functional pathways were observed only for the Unique and H37Rv strains while certain biological functions may be associated with other strain signatures. This study demonstrated that strains of M. tuberculosis induce differential gene expression and strain-specific molecular signatures in pulmonary epithelial cells. Specific signatures induced by clinical strains of M. tuberculosis can be further explored for novel host-associated biomarkers and adjunctive immunotherapies.

  16. Analysis of the tensile stress-strain behavior of elastomers at constant strain rates. I - Criteria for separability of the time and strain effects

    Science.gov (United States)

    Hong, S. D.; Fedors, R. F.; Schwarzl, F.; Moacanin, J.; Landel, R. F.

    1981-01-01

    A theoretical analysis of the tensile stress-strain relation of elastomers at constant strain rate is presented which shows that the time and the stress effect are separable if the experimental time scale coincides with a segment of the relaxation modulus that can be described by a single power law. It is also shown that time-strain separability is valid if the strain function is linearly proportional to the Cauchy strain, and that when time-strain separability holds, two strain-dependent quantities can be obtained experimentally. In the case where time and strain effect are not separable, superposition can be achieved only by using temperature and strain-dependent shift factors.

  17. The effect of ivermectin in seven strains of Aedes aegypti (Diptera: Culicidae) including a genetically diverse laboratory strain and three permethrin resistant strains.

    Science.gov (United States)

    Deus, K M; Saavedra-Rodriguez, K; Butters, M P; Black, W C; Foy, B D

    2012-03-01

    Seven different strains of Aedes aegypti (L.), including a genetically diverse laboratory strain, three laboratory-selected permethrin-resistant strains, a standard reference strain, and two recently colonized strains were fed on human blood containing various concentrations of ivermectin. Ivermectin reduced adult survival, fecundity, and hatch rate of eggs laid by ivermectin-treated adults in all seven strains. The LC50 of ivermectin for adults and the concentration that prevented 50% of eggs from hatching was calculated for all strains. Considerable variation in adult survival after an ivermectin-bloodmeal occurred among strains, and all three permethrin-resistant strains were significantly less susceptible to ivermectin than the standard reference strain. The hatch rate after an ivermectin bloodmeal was less variable among strains, and only one of the permethrin-resistant strains differed significantly from the standard reference strain. Our studies suggest that ivermectin induces adult mortality and decreases the hatch rate of eggs through different mechanisms. A correlation analysis of log-transformed LC50 among strains suggests that permethrin and ivermectin cross-resistance may occur.

  18. Genomics of Clostridium botulinum group III strains.

    Science.gov (United States)

    Sakaguchi, Yoshihiko; Suzuki, Tomonori; Yamamoto, Yumiko; Nishikawa, Atsushi; Oguma, Keiji

    2015-05-01

    In Clostridium botulinum, the characteristics of type C and D strains are quite different from other types, and they are classified as group III. They produce C2 binary toxin and C3 exoenzyme in addition to type C and D neurotoxins. Two different phages and many plasmids are identified in the organisms. The genes of neurotoxin and C3 exoenzyme are converted from toxigenic strains to non-toxigenic strains by the specific bacteriophages (phages), whereas, the C2 toxin gene is carried by large or small plasmids. Classification of type C and D strains has been in confusion because 1) antigenicity of type C and D neurotoxins is complex, 2) the cells produce two types of toxins, neurotoxin and C2 toxin, and 3) some non-toxigenic strains can be converted to produce C or D neurotoxin by the infection with phages. Until now, entire nucleotide sequences of cell chromosomes, phages, and plasmids have been determined. Since both genetic and protein-chemical analyses have been clarifying the above confusions, these data are reviewed historically.

  19. Cyclic Strain Enhances Cellular Uptake of Nanoparticles

    Directory of Open Access Journals (Sweden)

    Jia Hu

    2015-01-01

    Full Text Available Nanoparticles (NPs have gained increasing interest in recent years due to their potential use as drug carrier, imaging, and diagnostic agents in pharmaceutical and biomedical applications. While many cells in vivo experience mechanical forces, little is known about the correlation of the mechanical stimulation and the internalization of NPs into cells. This paper investigates the effects of applied cyclic strain on NP uptake by cells. Bovine aortic endothelial cells (BAECs were cultured on collagen-coated culture plates and placed under cyclic equal-axial strains. NPs of sizes ranging from 50 to 200 nm were loaded at a concentration of 0.02 mg/mL and cyclic strains from 5 to 15% were applied to the cells for one hour. The cyclic strain results in a significant enhancement in NP uptake, which increases almost linearly with strain level. The enhanced uptake also depends on size of the NPs with the highest uptake observed on 100 nm NP. The effect of enhanced NP uptake lasts around 13 hours after cyclic stretch. Such in vitro cell stretch systems mimic physiological conditions of the endothelial cells in vivo and could potentially serve as a biomimetic platform for drug therapeutic evaluation.

  20. Fast flexible electronics with strained silicon nanomembranes.

    Science.gov (United States)

    Zhou, Han; Seo, Jung-Hun; Paskiewicz, Deborah M; Zhu, Ye; Celler, George K; Voyles, Paul M; Zhou, Weidong; Lagally, Max G; Ma, Zhenqiang

    2013-01-01

    Fast flexible electronics operating at radio frequencies (>1 GHz) are more attractive than traditional flexible electronics because of their versatile capabilities, dramatic power savings when operating at reduced speed and broader spectrum of applications. Transferrable single-crystalline Si nanomembranes (SiNMs) are preferred to other materials for flexible electronics owing to their unique advantages. Further improvement of Si-based device speed implies significant technical and economic advantages. While the mobility of bulk Si can be enhanced using strain techniques, implementing these techniques into transferrable single-crystalline SiNMs has been challenging and not demonstrated. The past approach presents severe challenges to achieve effective doping and desired material topology. Here we demonstrate the combination of strained- NM-compatible doping techniques with self-sustained-strain sharing by applying a strain-sharing scheme between Si and SiGe multiple epitaxial layers, to create strained print-transferrable SiNMs. We demonstrate a new speed record of Si-based flexible electronics without using aggressively scaled critical device dimensions.

  1. [Vancomycin-resistant Enterococcus spp. strains].

    Science.gov (United States)

    Kozuszko, Sylwia; Bogiel, Tomasz; Gospodarek, Eugenia

    2009-01-01

    The aim of our study was to evaluate a frequency of isolation and susceptibility to antibiotics of vancomycin-resistant enterococci isolated between 2005 and the first half of the 2009 from patients of University Hospital of Dr. A. Jurasz Collegium Medicum of L. Rydygier in Bydgoszcz Nicolaus Copernicus University in Toruli. Study shows increasing frequency of VRE isolation from two in 2005, 8 in 2006, 30 in 2007 to 79 in 2008 and 40 in the first half of 2009 year. Among all isolated VRE strains E. faecium definitely predominated (75.0-90.0% in 2006-2009). The majority of strains were obtained from patients of the Pediatrics, Hematology and Oncology Clinic (43,4%) and Pediatric Surgery Clinic (41.5%). VRE strains were mainly isolated from digestive tract (79,9%). The isolates demonstrated frequently resistance to penicillin, ampicillin, ciprofloxacin, rifampicin and chloramphenicol. Percentage of VRE strain resistant to aminoglycosides decreased during the last four years of study. Over 56% of VRE isolates showed resistance to teicoplanin. Linezolid and quinupristin-dalfopristin were the only drugs presenting activity against isolated VRE strains.

  2. [Carbapenem-resistant Acinetobacter baumannii strains].

    Science.gov (United States)

    Bogiel, Tomasz; Kwiecińska-Piróg, Joanna; Jachna-Sawicka, Katarzyna; Gospodarek, Eugenia

    2010-01-01

    A. baumannii rods are opportunistic pathogens responsible generally for nosocomial infections. Resistance to carbapenems, observed among them, is a serious threat due to ability to be transmitted between bacterial species. The aim of our study was to evaluate the frequency of isolation and susceptibility to antibiotics of resistant to imipenem and/or meropenem A. baumannii strains isolated between 2007 and 2009 from patients of University Hospital of dr A. Jurasz Collegium Medicum of L. Rydygier in Bydgoszcz Nicolaus Copernicus University in Toruń. Study shows increasing frequency of isolation that type of strains from 4 in 2007 to 95 in 2008 and 67 in 2009. Percentage of imipenem-resistant isolates raised to 27.6% in 2008 and 31.0% in 2009. Meropenem-resistant A. baumannii isolates frequency changed from 2.1% in 2007 to 31.2% and 34.6%, in 2008 and 2009, respectively. The majority of strains were obtained from patients of the Intensive Care Units and surgery clinics. Examined A. baumannii strains were generally isolated from bronchoalveolar lavage (25.3%) and wound (18.1%) or throat (12.0%) swabs samples. The isolates demonstrated full resistance to norfloxacin, ciprofloxacin, and chloramphenicol. Ampicillin/sulbactam (24.8%), tobramycin (8.1%) and colistin (1.5%) presented the highest in vitro activity against isolated strains.

  3. Cyclomodulins in urosepsis strains of Escherichia coli.

    Science.gov (United States)

    Dubois, Damien; Delmas, Julien; Cady, Anne; Robin, Frédéric; Sivignon, Adeline; Oswald, Eric; Bonnet, Richard

    2010-06-01

    Determinants of urosepsis in Escherichia coli remain incompletely defined. Cyclomodulins (CMs) are a growing functional family of toxins that hijack the eukaryotic cell cycle. Four cyclomodulin types are actually known in E. coli: cytotoxic necrotizing factors (CNFs), cycle-inhibiting factor (Cif), cytolethal distending toxins (CDTs), and the pks-encoded toxin. In the present study, the distribution of CM-encoding genes and the functionality of these toxins were investigated in 197 E. coli strains isolated from patients with community-acquired urosepsis (n = 146) and from uninfected subjects (n = 51). This distribution was analyzed in relation to the phylogenetic background, clinical origin, and antibiotic resistance of the strains. It emerged from this study that strains harboring the pks island and the cnf1 gene (i) were strongly associated with the B2 phylogroup (P, urosepsis origin (P, urosepsis groups, suggesting that the pks island is more important for the colonization process and the cnf1 gene for virulence. pks- or cnf1-harboring strains were significantly associated with susceptibility to antibiotics (amoxicillin, cotrimoxazole, and quinolones [P, <0.001 to 0.043]). Otherwise, only 6% and 1% of all strains harbored the cdtB and cif genes, respectively, with no particular distribution by phylogenetic background, antimicrobial susceptibility, or clinical origin.

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

    Directory of Open Access Journals (Sweden)

    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.

  5. Assessment of myocardial strain and strain rate by tissue doppler echocar-diography

    Directory of Open Access Journals (Sweden)

    Ekimova N.A.

    2013-03-01

    Full Text Available The objective of the article is to review the current data on the method of quantitative evaluation of cardiac mechanics — assessment of myocardial strain and strain rate according to the results of the tissue Doppler echocardiography and prospects of its clinical application.

  6. Strain differences in hippocampal EEG are related to strain differences in behaviour in rats

    NARCIS (Netherlands)

    Lier, H. van; Drinkenburg, W.H.I.M.; Coenen, A.M.L.

    2003-01-01

    To date, EEG studies towards strain differences have focussed on pharmacologically altered or pathological EEG activity, but only few studies have investigated strain differences and normal EEG activity. A strong relation between behaviour and EEG activity has been demonstrated, especially for

  7. Computer modelling of bone's adaptation: the role of normal strain, shear strain and fluid flow.

    Science.gov (United States)

    Tiwari, Abhishek Kumar; Prasad, Jitendra

    2017-04-01

    Bone loss is a serious health problem. In vivo studies have found that mechanical stimulation may inhibit bone loss as elevated strain in bone induces osteogenesis, i.e. new bone formation. However, the exact relationship between mechanical environment and osteogenesis is less clear. Normal strain is considered as a prime stimulus of osteogenic activity; however, there are some instances in the literature where osteogenesis is observed in the vicinity of minimal normal strain, specifically near the neutral axis of bending in long bones. It suggests that osteogenesis may also be induced by other or secondary components of mechanical environment such as shear strain or canalicular fluid flow. As it is evident from the literature, shear strain and fluid flow can be potent stimuli of osteogenesis. This study presents a computational model to investigate the roles of these stimuli in bone adaptation. The model assumes that bone formation rate is roughly proportional to the normal, shear and fluid shear strain energy density above their osteogenic thresholds. In vivo osteogenesis due to cyclic cantilever bending of a murine tibia has been simulated. The model predicts results close to experimental findings when normal strain, and shear strain or fluid shear were combined. This study also gives a new perspective on the relation between osteogenic potential of micro-level fluid shear and that of macro-level bending shear. Attempts to establish such relations among the components of mechanical environment and corresponding osteogenesis may ultimately aid in the development of effective approaches to mitigating bone loss.

  8. Mechanical properties of biaxially strained poly(L-lactide) tubes: Strain rate and temperature dependence

    DEFF Research Database (Denmark)

    Løvdal, Alexandra Liv Vest; Andreasen, Jens Wenzel; Mikkelsen, Lars Pilgaard

    2017-01-01

    Poly(l-lactide) (PLLA) is a bioabsorbable polymer with high stiffness and strength compared to the other commercially available bioabsorbable polymers. The properties of PLLA can be improved by straining, causing deformation-mediated molecular orientation. PLLA tubes were biaxially strained above...

  9. Genetic characterization of measles vaccine strains.

    Science.gov (United States)

    Bankamp, Bettina; Takeda, Makoto; Zhang, Yan; Xu, Wenbo; Rota, Paul A

    2011-07-01

    The complete genomic sequences of 9 measles vaccine strains were compared with the sequence of the Edmonston wild-type virus. AIK-C, Moraten, Rubeovax, Schwarz, and Zagreb are vaccine strains of the Edmonston lineage, whereas CAM-70, Changchun-47, Leningrad-4 and Shanghai-191 were derived from 4 different wild-type isolates. Nucleotide substitutions were found in the noncoding regions of the genomes as well as in all coding regions, leading to deduced amino acid substitutions in all 8 viral proteins. Although the precise mechanisms involved in the attenuation of individual measles vaccines remain to be elucidated, in vitro assays of viral protein functions and recombinant viruses with defined genetic modifications have been used to characterize the differences between vaccine and wild-type strains. Although almost every protein contributes to an attenuated phenotype, substitutions affecting host cell tropism, virus assembly, and the ability to inhibit cellular antiviral defense mechanisms play an especially important role in attenuation.

  10. Diffraction Correlation to Reconstruct Highly Strained Particles

    Science.gov (United States)

    Brown, Douglas; Harder, Ross; Clark, Jesse; Kim, J. W.; Kiefer, Boris; Fullerton, Eric; Shpyrko, Oleg; Fohtung, Edwin

    2015-03-01

    Through the use of coherent x-ray diffraction a three-dimensional diffraction pattern of a highly strained nano-crystal can be recorded in reciprocal space by a detector. Only the intensities are recorded, resulting in a loss of the complex phase. The recorded diffraction pattern therefore requires computational processing to reconstruct the density and complex distribution of the diffracted nano-crystal. For highly strained crystals, standard methods using HIO and ER algorithms are no longer sufficient to reconstruct the diffraction pattern. Our solution is to correlate the symmetry in reciprocal space to generate an a priori shape constraint to guide the computational reconstruction of the diffraction pattern. This approach has improved the ability to accurately reconstruct highly strained nano-crystals.

  11. Developments of borehole strain observation outside China

    Institute of Scientific and Technical Information of China (English)

    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.

  12. Survival and activity of individual bioaugmentation strains

    DEFF Research Database (Denmark)

    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...... allow us to address these limitations. Here a complementing set of general applicable molecular methods are presented that provides detailed information on the performance of individual bioaugmentation strains under in situ conditions. The approach involves genome sequencing to establish highly specific...... qPCR and RT-qPCR tools for cell enumerations and expression of involved genes, stable isotope probing to follow growth on the target compounds and GFP-tagging to visualize the bioaugmentation strains directly in samples, all in combination with removal studies of the target compounds. The concept...

  13. High sensitivity knitted fabric strain sensors

    Science.gov (United States)

    Xie, Juan; Long, Hairu; Miao, Menghe

    2016-10-01

    Wearable sensors are increasingly used in smart garments for detecting and transferring vital signals and body posture, movement and respiration. Existing fabric strain sensors made from metallized yarns have low sensitivity, poor comfort and low durability to washing. Here we report a knitted fabric strain sensor made from a cotton/stainless steel (SS) fibre blended yarn which shows much higher sensitivity than sensors knitted from metallized yarns. The fabric feels softer than pure cotton textiles owing to the ultrafine stainless steel fibres and does not lose its electrical property after washing. The reason for the high sensitivity of the cotton/SS knitted fabric sensor was explored by comparing its sensing mechanism with the knitted fabric sensor made from metallized yarns. The results show that the cotton/SS yarn-to-yarn contact resistance is highly sensitive to strain applied to hooked yarn loops.

  14. Nuclear transplantation in different strains of zebrafish

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Single later blastula nuclei from AB strain of zebrafish (Danio rerio) were transplanted into enucleated unfertilized eggs of Long fin strain. Of 1119 cloning embryos, 14 reconstructed embryos developed into fry. DNA fingerprinting systems of the cloned fish were similar to those of the nuclear donor fish, but were distinctly different from those of the nuclear recipient fish. It confirmed that the genetic material originated from nuclear donor cell other than from nuclear recipient egg. The research suggested that the basic technique for nuclear transplantation performed with different strains of zebrafish has made a breakthrough. It should be helpful for the study of some important developmental problems such as gene function, the regulation of gene expression during animal development, the developmental potential of a nucleus and the interactions between the donor nucleus and the recipient cytoplasm, etc.

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

    CERN Document Server

    Lee, HyunSuk

    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 decomposition is suggested. A new decomposition method adopts multiplying decomposition tensors or matrices to not only stress and strain but also constitutive and compliance relation. With this, we also show its practical usage on FEM and BEM in terms of tensors and matrices.

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

    DEFF Research Database (Denmark)

    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...

  17. Genome organization of epidemic Acinetobacter baumannii strains

    Directory of Open Access Journals (Sweden)

    Triassi Maria

    2011-10-01

    Full Text Available Abstract Background Acinetobacter baumannii is an opportunistic pathogen responsible for hospital-acquired infections. A. baumannii epidemics described world-wide were caused by few genotypic clusters of strains. The occurrence of epidemics caused by multi-drug resistant strains assigned to novel genotypes have been reported over the last few years. Results In the present study, we compared whole genome sequences of three A. baumannii strains assigned to genotypes ST2, ST25 and ST78, representative of the most frequent genotypes responsible for epidemics in several Mediterranean hospitals, and four complete genome sequences of A. baumannii strains assigned to genotypes ST1, ST2 and ST77. Comparative genome analysis showed extensive synteny and identified 3068 coding regions which are conserved, at the same chromosomal position, in all A. baumannii genomes. Genome alignments also identified 63 DNA regions, ranging in size from 4 o 126 kb, all defined as genomic islands, which were present in some genomes, but were either missing or replaced by non-homologous DNA sequences in others. Some islands are involved in resistance to drugs and metals, others carry genes encoding surface proteins or enzymes involved in specific metabolic pathways, and others correspond to prophage-like elements. Accessory DNA regions encode 12 to 19% of the potential gene products of the analyzed strains. The analysis of a collection of epidemic A. baumannii strains showed that some islands were restricted to specific genotypes. Conclusion The definition of the genome components of A. baumannii provides a scaffold to rapidly evaluate the genomic organization of novel clinical A. baumannii isolates. Changes in island profiling will be useful in genomic epidemiology of A. baumannii population.

  18. Pheromonal divergence between two strains of Spodoptera frugiperda

    NARCIS (Netherlands)

    Unbehend, M.; Hänniger, S.; Meagher, R.L.; Heckel, D.G.; Groot, A.T.

    2013-01-01

    Spodoptera frugiperda consists of two genetically and behaviorally different strains, the corn- and the rice-strain, which seem to be in the process of sympatric speciation. We investigated the role of strain-specific sexual communication as a prezygotic mating barrier between both strains by analyz

  19. Ciprofloxacin susceptibility reduction of Salmonella strains isolated from outbreaks

    Directory of Open Access Journals (Sweden)

    Roberta B. Souza

    2010-06-01

    Full Text Available The antimicrobial susceptibility of 212 Salmonella strains isolated from patients and foods was evaluated and 45% were found to be resistant to nalidixic acid. Nalidixic acid resistant strains showed a higher minimal inhibitory concentration for ciprofloxacin than sensitive strains. During the study an increase of strains with reduced susceptibility to ciprofloxacin was also observed.

  20. MM98.57 Quantification of Combined Strain Paths

    DEFF Research Database (Denmark)

    Nielsen, Morten Sturgård; Wanheim, Tarras

    1998-01-01

    is to describe the total strain history as a curve in the 6-dimensional shear strain, normal strain space. In order to be able to use these experimental data for calculation, the development of this strain curve must be transformed into a set of scalar relations that may be used for predicting the yield surface...

  1. Manipulation of electronic structure in WSe2 monolayer by strain

    Science.gov (United States)

    Yang, Cong-xia; Zhao, Xu; Wei, Shu-yi

    2016-11-01

    In this paper, we study the electronic properties of WSe2 monolayer with biaxial tensile strain and compressive strain by using first principles based on the density function theory. Under the biaxial tensile strain, WSe2 monolayer retains direct band gap with increasing strain and the band gap of WSe2 continuously decreases with increasing strain, eventually turn to metal when strain is equal to or more than 13%. Under the biaxial compressive strain, WSe2 monolayer turns to indirect gap and the band gap continuously decreases with increasing strain, finally turn to metal when strain is up to -7%. The strain can reduce the band gap of the WSe2 monolayer regardless of the strain direction. By comparison, we can see that the tensile strain appears to be more effective in reducing the band gap of pristine WSe2 monolayer than the compressive strain from -5% to 5%. But the band gap turns to zero quickly from -6% to -7% under compressive strain, however for tensile strain from 5% to 13%, the band gap decreases slowly. Based on the further analysis of the projected charge density for WSe2 monolayer, the fundamental reason of the change of band structure under biaxial tensile strain is revealed.

  2. Dynamic strain aging in magnesium oxide single crystals

    Science.gov (United States)

    Srinivasan, M.; Stoebe, T. G.

    1973-01-01

    Strain rate change transients are considered together with aspects of serrated flow, questions of flow stress and work hardening during dynamic strain aging, and time, temperature, and prestrain dependence of strain aging. On continuing the deformation process after aging for certain periods of time for a particular strain, a subsidiary load drop is sometimes observed in addition to the main yield drops.

  3. Chronic Wasting Disease Prion Strain Emergence and Host Range Expansion.

    Science.gov (United States)

    Herbst, Allen; Velásquez, Camilo Duque; Triscott, Elizabeth; Aiken, Judd M; McKenzie, Debbie

    2017-09-01

    Human and mouse prion proteins share a structural motif that regulates resistance to common chronic wasting disease (CWD) prion strains. Successful transmission of an emergent strain of CWD prion, H95(+), into mice resulted in infection. Thus, emergent CWD prion strains may have higher zoonotic potential than common strains.

  4. ANISOTROPIC STRAIN-HARDENING IN POLYCRYSTALLINE COPPER AND ALUMINUM

    NARCIS (Netherlands)

    HESS, F

    1993-01-01

    A new viscoplastic model for the plastic stress-strain behaviour of f.c.c. metals is presented. In this model the strain hardening results from increasing dislocation densities. The observed stagnation of strain hardening after strain reversals is explained by a lowering of the increase in dislocati

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

    NARCIS (Netherlands)

    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

  6. Longitudinal residual strain and stress-strain relationship in rat small intestine

    Directory of Open Access Journals (Sweden)

    Fan Yanhua

    2006-06-01

    Full Text Available Abstract Background To obtain a more detailed description of the stress-free state of the intestinal wall, longitudinal residual strain measurements are needed. Furthermore, data on longitudinal stress-strain relations in visceral organs are scarce. The present study aims to investigate the longitudinal residual strain and the longitudinal stress-strain relationship in the rat small intestine. Methods The longitudinal zero-stress state was obtained by cutting tissue strips parallel to the longitudinal axis of the intestine. The longitudinal residual stress was characterized by a bending angle (unit: degrees per unit length and positive when bending outwards. Residual strain was computed from the change in dimensions between the zero-stress state and the no-load state. Longitudinal stresses and strains were computed from stretch experiments in the distal ileum at luminal pressures ranging from 0–4 cmH2O. Results Large morphometric variations were found between the duodenum and ileum with the largest wall thickness and wall area in the duodenum and the largest inner circumference and luminal area in the distal ileum (p 0.5. The longitudinal residual strain was tensile at the serosal surface and compressive at the mucosal surface. Hence, the neutral axis was approximately in the mid-wall. The longitudinal residual strain and the bending angle was not uniform around the intestinal circumference and had the highest values on the mesenteric sides (p α constant increased with the pressure, indicating the intestinal wall became stiffer in longitudinal direction when pressurized. Conclusion Large longitudinal residual strains reside in the small intestine and showed circumferential variation. This indicates that the tissue is not uniform and cannot be treated as a homogenous material. The longitudinal stiffness of the intestinal wall increased with luminal pressure. Longitudinal residual strains must be taken into account in studies of

  7. High Strain Rate Characterisation of Composite Materials

    DEFF Research Database (Denmark)

    Eriksen, Rasmus Normann Wilken

    The high strain rate characterisation of FRP materials present the experimenter with a new set of challenges in obtaining valid experimental data. These challenges were addressed in this work with basis in classic wave theory. The stress equilibrium process for linear elastic materials, as fibre...... 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...

  8. Cells as strain-cued automata

    Science.gov (United States)

    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

  9. Tensile strain mapping in flat germanium membranes

    Energy Technology Data Exchange (ETDEWEB)

    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.

  10. Atmospheric corrosion sensor based on strain measurement

    Science.gov (United States)

    Kasai, Naoya; Hiroki, Masatoshi; Yamada, Toshirou; Kihira, Hiroshi; Matsuoka, Kazumi; Kuriyama, Yukihisa; Okazaki, Shinji

    2017-01-01

    In this paper, an in situ atmospheric corrosion sensor based on strain measurement is discussed. The theoretical background for measuring the reduction in thickness of low carbon steel is also presented. Based on the theoretical considerations, a test piece and apparatus for an atmospheric corrosion sensor were designed. Furthermore, in a dry–wet cyclic accelerated exposure experiment, the measured strain indicated thinning of the test piece, although the corrosion product generated on the surface of the test piece affected the results. The atmospheric corrosion sensor would be effective for evaluating atmospheric corrosion of many types of infrastructure.

  11. Propagating edge states in strained honeycomb lattices

    Science.gov (United States)

    Salerno, Grazia; Ozawa, Tomoki; Price, Hannah M.; Carusotto, Iacopo

    2017-06-01

    We investigate the helically propagating edge states associated with pseudo-Landau levels in strained honeycomb lattices. We exploit chiral symmetry to derive a general criterion for the existence of these propagating edge states in the presence of only nearest-neighbor hoppings and we verify our criterion using numerical simulations of both uniaxially and trigonally strained honeycomb lattices. We show that the propagation of the helical edge state can be controlled by engineering the shape of the edges. Sensitivity to chiral-symmetry-breaking next-nearest-neighbor hoppings is assessed. Our result opens up an avenue toward the precise control of edge modes through manipulation of the edge shape.

  12. Unsteady Aerodynamic Force Sensing from Strain Data

    Science.gov (United States)

    Pak, Chan-Gi

    2017-01-01

    A simple approach for computing unsteady aerodynamic forces from simulated measured strain data is proposed in this study. First, the deflection and slope of the structure are computed from the unsteady strain using the two-step approach. Velocities and accelerations of the structure are computed using the autoregressive moving average model, on-line parameter estimator, low-pass filter, and a least-squares curve fitting method together with analytical derivatives with respect to time. Finally, aerodynamic forces over the wing are computed using modal aerodynamic influence coefficient matrices, a rational function approximation, and a time-marching algorithm.

  13. Tensile Properties of TWIP Steel at High Strain Rate

    Institute of Scientific and Technical Information of China (English)

    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.

  14. Dynamics of Dual Infection with Campylobacter jejuni Strains in Chickens Reveals Distinct Strain-to-Strain Variation in Infection Ecology

    Science.gov (United States)

    Wigley, Paul; Humphrey, Suzanne; Kemmett, Kirsty; Lacharme-Lora, Lizeth; Humphrey, Tom; Williams, Nicola

    2014-01-01

    Although multiple genotypes of Campylobacter jejuni may be isolated from the same commercial broiler flock, little is known about the infection dynamics of different genotypes within individuals or their colonization sites within the gut. Single experimental infections with C. jejuni M1 (sequence type 137, clonal complex 45) and C. jejuni 13126 (sequence type 21, clonal complex 21) revealed that 13126 colonized the ceca at significantly higher levels. The dissemination and colonization sites of the two C. jejuni strains then were examined in an experimental broiler flock. Two 33-day-old broiler chickens were infected with M1 and two with 13126, and 15 birds were left unchallenged. Cloacal swabs were taken postinfection to determine the colonization and shedding of each strain. By 2 days postinfection (dpi), 8/19 birds were shedding M1 whereas none were shedding 13126. At 8 dpi, all birds were shedding both strains. At 18 dpi, liver and cecal levels of each isolate were quantified, while in 10 birds they also were quantified at nine sites throughout the gastrointestinal (GI) tract. 13126 was found throughout the GI tract, while M1 was largely restricted to the ceca and colon. The livers of 7/19 birds were culture positive for 13126 only. These data show that 13126 has a distinctly different infection biology than strain M1. It showed slower colonization of the lower GI tract but was more invasive and able to colonize at a high level throughout the GI tract. The finding that C. jejuni strains have markedly different infection ecologies within the chicken has implications for control in the poultry industry and suggests that the contamination risk of edible tissues is dependent on the isolate involved. PMID:25107966

  15. Serological Strains of Tobacco Ringspot Virus Transmitted by Xiphinema americanum.

    Science.gov (United States)

    Rush, M C

    1970-07-01

    Five serological strains of tobacco ringspot virus isolated from naturally infected tobacco in North Carolina, and a strain isolated from watermelon in the Rio Grande Valley of Texas were transmitted from cucumber to cucumber by mass-screened and handpicked Xiphinerna americanum from North Carolina. The Eucharis mottle strain from Peru was not transmitted, indicating that a specific strain-vector relationship may exist between the geographically isolated strains from North and South America.

  16. Genome Sequences of Bacillus thuringiensis Serovar kurstaki Strain BP865 and B. thuringiensis Serovar aizawai Strain HD-133

    Science.gov (United States)

    Jeong, Haeyoung

    2017-01-01

    ABSTRACT We report the draft genome sequences of two insecticidal strains against lepidopteran pests, Bacillus thuringiensis serovar kurstaki strain BP865, an isolate from the South Korean phylloplane, and strain HD-133, a reference strain of B. thuringiensis serovar aizawai. PMID:28153898

  17. Perceptual strain index for heat strain assessment in an experimental study: an application to construction workers.

    Science.gov (United States)

    Yang, Y; Chan, Albert P C

    2015-02-01

    Although the physiological strain index (PhSI) is universal and comprehensive, its restrictions are recognized in terms of invasive on-site measurements and the requirement of accurate instruments. The perceptual strain index (PeSI) has been proposed as a user-friendly and practical indicator for heat strain. However, the application of this index in assessing the heat strain of construction workers has yet to be examined and documented. This study aims to ascertain the reliability and applicability of PeSI in an experimental setting that simulates a stressful working environment (i.e., environment, work uniform, and work pace) experienced by construction workers. Ten males and two females performed intermittent exercise on a treadmill while wearing a summer work uniform at 34.5 °C and 75% relative humidity in a climatic chamber. Physiological parameters (core temperature, heart rate) and perceptual variables (thermal sensation, perceived exertion) were collated synchronously at 3 min intervals. The results of two-way repeated measures analysis of variance (clothing×time) revealed that the PeSI was useful in differentiating the heat strain levels between different work uniforms. Not only did the PeSI change in the same general manner with the PhSI, but it was also powerful in reflecting different levels of physiological strain. Thus, the PeSI offers considerable promise for heat strain assessment under simulated working conditions.

  18. Electronic and optical properties of strained graphene and other strained 2D materials: a review

    Science.gov (United States)

    Naumis, Gerardo G.; Barraza-Lopez, Salvador; Oliva-Leyva, Maurice; Terrones, Humberto

    2017-09-01

    This review presents the state of the art in strain and ripple-induced effects on the electronic and optical properties of graphene. It starts by providing the crystallographic description of mechanical deformations, as well as the diffraction pattern for different kinds of representative deformation fields. Then, the focus turns to the unique elastic properties of graphene, and to how strain is produced. Thereafter, various theoretical approaches used to study the electronic properties of strained graphene are examined, discussing the advantages of each. These approaches provide a platform to describe exotic properties, such as a fractal spectrum related with quasicrystals, a mixed Dirac–Schrödinger behavior, emergent gravity, topological insulator states, in molecular graphene and other 2D discrete lattices. The physical consequences of strain on the optical properties are reviewed next, with a focus on the Raman spectrum. At the same time, recent advances to tune the optical conductivity of graphene by strain engineering are given, which open new paths in device applications. Finally, a brief review of strain effects in multilayered graphene and other promising 2D materials like silicene and materials based on other group-IV elements, phosphorene, dichalcogenide- and monochalcogenide-monolayers is presented, with a brief discussion of interplays among strain, thermal effects, and illumination in the latter material family.

  19. Entire deformational characteristics and strain localization of jointed rock specimen in plane strain compression

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Shear band (SB),axial, lateral and volumetric strains as well as Poisson's ratio of anisotropic jointed rock specimen (JRS) were modeled by Fast Lagrangian Analysis of Continua (FLAC). Failure criterion of rock was a composited Mohr-Coulomb criterion with tension cut-off. An inclined joint was treated as square elements of ideal plastic material beyond the peak strength. Several FISH functions were written to automatically find the addresses of elements in the joint and to calculate the entire deformational characteristics of plane strain JRS. The results show that for moderate joint inclination (JI), strain is only concentrated into the joint governing the behavior of JRS,leading to ideal plastic responses in axial and lateral directions. For higher JI, the post-peak stress-axial and lateral strain curves become steeper as JI increases owing to the increase of new SB's length. Lateral expansion and precursor to the unstable failure are the most apparent, resulting in the highest Poisson's ratio and even negative volumetric strain. For lower JI, the entire post-peak deformational characteristics are independent of JI. The lowest lateral expansion occurs, leading to the lowest Poisson's ratio and positive volumetric strain all along. The present prediction on anisotropic strength in plane strain compression qualitatively agrees with the results in triaxial tests of rocks.The JI calculated by Jaeger's formula overestimates that related to the minimum strength. Advantages of the present numerical model over the Jaeger's model are pointed out.

  20. Genomic comparison between attenuated Chinese equine infectious anemia virus vaccine strains and their parental virulent strains.

    Science.gov (United States)

    Wang, Xuefeng; Wang, Shuai; Lin, Yuezhi; Jiang, Chenggang; Ma, Jian; Zhao, Liping; Lv, Xiaoling; Wang, Fenglong; Shen, Rongxian; Kong, Xiangang; Zhou, Jianhua

    2011-02-01

    A lentiviral vaccine, live attenuated equine infectious anemia virus (EIAV) vaccine, was developed in the 1970s, and this has made tremendous contributions to the control of equine infectious anemia (EIA) in China. Four key virus strains were generated during the attenuation of the EIAV vaccine: the original Liao-Ning strain (EIAV(LN40)), a donkey-adapted virulent strain (EIAV(DV117)), a donkey-leukocyte-attenuated vaccine strain (EIAV(DLV121)), and a fetal donkey dermal cell (FDD)-adapted vaccine strain (EIAV(FDDV13)). In this study, we analyzed the proviral genomes of these four EIAV strains and found a series of consensus substitutions among these strains. These mutations provide useful information for understanding the genetic basis of EIAV attenuation. Our results suggest that multiple mutations in a variety of genes in our attenuated EIAV vaccines not only provide a basis for virulence attenuation and induction of protective immunity but also greatly reduce the risk of reversion to virulence.

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

    Directory of Open Access Journals (Sweden)

    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.

  2. Effective stress coefficient for uniaxial strain condition

    DEFF Research Database (Denmark)

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

    2012-01-01

    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....

  3. Charge and Strain Control of Interface Magnetism

    Science.gov (United States)

    Fitzsimmons, M. R.; Dumesnil, K.; Jaouen, N.; Maroutian, T.; Agnus, G.; Tonnerre, J.-M.; Kirby, B.; Fohtung, E.; Holladay, B.; Fullerton, E. E.; Shpyrko, O.; Sinha, S. K.; Wang, Q.; Chen, A.; Jia, Q. X.

    2015-03-01

    We studied the influence of an electric field applied to an La0.67Sr0.33MnO3 (LSMO) layer in a LSMO/Pb(Zr0.2Ti0.8) O3 (PZT)/Nb-doped SrTiO3 (STO) heterostructure by measuring its magnetization depth profile using resonant x-ray magnetic reflectivity. The saturation magnetization of the ferromagnetically-ordered LSMO was not affected by the direction of the polarization of the PZT. However, the ferromagnetic thickness and magnetization of the LSMO film at remanence were reduced for hole-charge accumulation at the LSMO/PZT interface. To understand the independent roles of strain and hole-doping, we performed neutron scattering experiments of La0.8Sr0.2MnO3 films grown on Nb-doped STO in which bending strain (via 4-point bending jig) or electric field (via parallel plate capacitor) was applied to the films. We observed that bending strain affects the saturation magnetization of the LSMO film, whereas electric field affects the remanent magnetization of the film. These observations suggest strain may be a more effective means to control magnetism than charge. This work has benefited from use of CINT(LANL), NIST Center for Neutron Research and the Synchrotron SOLEIL and funding from LANL/LDRD program, DOE-BES (UCSD) and DOD (NMSU).

  4. Strain Analysis of the de Mattia Test

    Directory of Open Access Journals (Sweden)

    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.

  5. Preliminary characterization of Rhizobium strains isolated from ...

    African Journals Online (AJOL)

    SERVER

    2008-03-18

    Mar 18, 2008 ... about the efficiency of crop inoculation (Graham, 1981;. Hardarson, 1993 ... Strains of Rhizobium sp. were obtained from root nodules of field grown chickpea plants .... 3.0 and 9.0 (Table 1), as observed for other R. ciceri.

  6. Photoacclimation of cultured strains of the cyanobacterium

    NARCIS (Netherlands)

    Bañares-España, E.; Kromkamp, J.C.; López-Rodas, V.; Costas, E.; Flores-Moya, A.

    2013-01-01

    The cyanobacterium Microcystis aeruginosa forms blooms that can consist of colonies. We have investigated how M.aeruginosa acclimatizes to changing light conditions such as can occur during blooms. Three different strains were exposed to two irradiance levels: lower (LL) and higher (HL) than the

  7. A novel limiting strain energy strength theory

    Institute of Scientific and Technical Information of China (English)

    LIU Guang-lian

    2009-01-01

    With applied dislocation theory,the effects of shear and normal stresses on the slide and climb motions at the same section of a crystal were analyzed.And,based on the synergetic effect of both normal and shear strain specific energies,the concept of the total equivalent strain specific energy (TESSE) at an oblique section and a new strength theory named as limiting strain energy strength theory (LSEST) were proposed.As for isotropic materials,the plastic yielding or brittle fracture of under uniaxial stress state would occur when the maximum TESSE reached the strain specific energy,also the expressions on the equivalent stresses and a function of failure of the LSEST under different principal stress states were obtained.Relationship formulas among the tensile,compressive and shear yield strengths for plastic metals were derived.These theoretical predictions,according to the LSEST,were consistent very well with experiment results of tensile,compressive and torsion tests of three plastic metals and other experiment results from open literatures.This novel LSEST might also help for strength calculation of other materials.

  8. Photonic skin for pressure and strain sensing

    Science.gov (United States)

    Chen, Xianfeng; Zhang, C.; van Hoe, B.; Webb, D. J.; Kalli, K.; van Steenberge, G.; Peng, G.-D.

    2010-04-01

    In this paper, we report on the strain and pressure testing of highly flexible skins embedded with Bragg grating sensors recorded in either silica or polymer optical fibre. The photonic skins, with a size of 10cm x 10cm and thickness of 1mm, were fabricated by embedding the polymer fibre or silica fibre containing Bragg gratings in Sylgard 184 from Dow Corning. Pressure sensing was studied using a cylindrical metal post placed on an array of points across the skin. The polymer fibre grating exhibits approximately 10 times the pressure sensitivity of the silica fibre and responds to the post even when it is placed a few centimetres away from the sensing fibre. Although the intrinsic strain sensitivities of gratings in the two fibre types are very similar, when embedded in the skin the polymer grating displayed a strain sensitivity approximately 45 times greater than the silica device, which also suffered from considerable hysteresis. The polymer grating displayed a near linear response over wavelength shifts of 9nm for 1% strain. The difference in behaviour we attribute to the much greater Young's modulus of the silica fibre (70 GPa) compared to the polymer fibre (3 GPa).

  9. Storage features of Lactobacillus Brevis strain 9

    Directory of Open Access Journals (Sweden)

    Utemurat Sagyndykov

    2013-03-01

    Full Text Available Current article presents the results of the research conducted on storing lactic bacteria. On the basis of results of experiments on liophilization of the culture of lactic bacteria Lactobacillus brevis strain №9, it has been concluded that the optimum way of storing the given culture is the method of liophilic drying with the vacuum soldering.

  10. High strain rate behaviour of polypropylene microfoams

    Science.gov (United States)

    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.

  11. Optical Hall effect in strained graphene

    Science.gov (United States)

    Nguyen, V. Hung; Lherbier, A.; Charlier, J.-C.

    2017-06-01

    When passing an optical medium in the presence of a magnetic field, the polarization of light can be rotated either when reflected at the surface (Kerr effect) or when transmitted through the material (Faraday rotation). This phenomenon is a direct consequence of the optical Hall effect arising from the light-charge carrier interaction in solid state systems subjected to an external magnetic field, in analogy with the conventional Hall effect. The optical Hall effect has been explored in many thin films and also more recently in 2D layered materials. Here, an alternative approach based on strain engineering is proposed to achieve an optical Hall conductivity in graphene without magnetic field. Indeed, strain induces lattice symmetry breaking and hence can result in a finite optical Hall conductivity. First-principles calculations also predict this strain-induced optical Hall effect in other 2D materials. Combining with the possibility of tuning the light energy and polarization, the strain amplitude and direction, and the nature of the optical medium, large ranges of positive and negative optical Hall conductivities are predicted, thus opening the way to use these atomistic thin materials in novel specific opto-electro-mechanical devices.

  12. Genomic comparison of Kingella kingae strains.

    Science.gov (United States)

    Fournier, Pierre-Edouard; Rouli, Laetitia; El Karkouri, Khalid; Nguyen, Thi-Tien; Yagupsky, Pablo; Raoult, Didier

    2012-11-01

    Kingella kingae is a betaproteobacterium from the order Neisseriales, and it is an agent of invasive infections in children. We sequenced the genome from the septic arthritis strain 11220434. It is composed of a 1,990,794-bp chromosome but no plasmid, and it contains 2,042 protein-coding genes and 52 RNA genes, including 3 rRNA genes.

  13. Thermal strain analysis of optic fiber sensors.

    Science.gov (United States)

    Her, Shiuh-Chuan; Huang, Chih-Ying

    2013-01-31

    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.

  14. Prediction of swelling rocks strain in tunneling

    Science.gov (United States)

    Parsapour, D.; Fahimifar, A.

    2016-05-01

    Swelling deformations leading to convergence of tunnels may result in significant difficulties during the construction, in particular for long term use of tunnels. By extracting an experimental based explicit analytical solution for formulating swelling strains as a function of time and stress, swelling strains are predicted from the beginning of excavation and during the service life of tunnel. Results obtained from the analytical model show a proper agreement with experimental results. This closed-form solution has been implemented within a numerical program using the finite element method for predicting time-dependent swelling strain around tunnels. Evaluating effects of swelling parameters on time-dependent strains and tunnel shape on swelling behavior around the tunnel according to this analytical solution is considered. The ground-support interaction and consequent swelling effect on the induced forces in tunnel lining is considered too. Effect of delay in lining installation on swelling pressure which acting on the lining and its structural integrity, is also evaluated. A MATLAB code of " SRAP" is prepared and applied to calculate all swelling analysis around tunnels based on analytical solution.

  15. "The Andromeda Strain" as Science and Literature.

    Science.gov (United States)

    Kaczmarek, Nancy

    Well-written, with a flair for character development, and focusing on controversial issues, Michael Crichton's novel "The Andromeda Strain" can precipitate lively discussions in science, English, and social studies classes and can help students to integrate all three areas. English and science teachers can collaborate in a variety of…

  16. Strain relief for power-cable connectors

    Science.gov (United States)

    Dean, W. T., III

    1980-01-01

    Easily fabricated grommet composed of polytetrafluoroethylene cylinder, containing U-shaped channels equally spaced around periphery, is used in power cable connectors to relieve strain on cables. Utilization of grommets provides more ease in cable insertion and removal. Potential applications include wiring in large residential and commercial buildings.

  17. Strain Measurement Technology for Corrosion Fatigue Specimen

    Institute of Scientific and Technical Information of China (English)

    ZHONG; Wei-hua; NING; Guang-sheng; ZHANG; Chang-yi; TONG; Zhen-feng; YANG; Wen

    2015-01-01

    Main pipeline is the key component of nuclear power plants(NPPs).Under the first loop water and low-cyclic load condition,the main pipeline may be induced to corrosion fatigue failure.Thus,it’s necessary to test and get the corrosion fatigue property of main pipeline material.During the corrosion fatigue test,the strain

  18. Antimicrobial resistance among Brazilian Corynebacterium diphtheriae strains

    Directory of Open Access Journals (Sweden)

    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.

  19. High strain rate behaviour of polypropylene microfoams

    Directory of Open Access Journals (Sweden)

    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.

  20. Characterizing large strain crush response of redwood

    Energy Technology Data Exchange (ETDEWEB)

    Cramer, S.M.; Hermanson, J.C. [Univ. of Wisconsin, Madison, WI (United States). Dept. of Civil and Environmental Engineering; McMurtry, W.M. [Sandia National Labs., Albuquerque, NM (United States)

    1996-12-01

    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 {minus}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.

  1. Measuring physical strain during ambulation with accelerometry

    NARCIS (Netherlands)

    Bussmann, J B; Hartgerink, I; van der Woude, L H; Stam, H J

    2000-01-01

    PURPOSE: To study the feasibility of ambulatory accelerometry in the evaluation of physical strain in walking at different speeds and different levels of economy. METHODS: Twelve able-bodied subjects performed a walking test on a treadmill with increasing walking speed. After a 6-wk period, these me

  2. Development of Industrial Yeast Platform Strains

    DEFF Research Database (Denmark)

    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...

  3. Silicon Germanium Strained Layers and Heterostructures

    Science.gov (United States)

    Willander, M.; Nur, O.; Jain, S. C.

    2004-01-01

    The integration of strained-Si1 xGex into Si technology has enhanced the performance and extended the functionality of Si based circuits. The improvement of device performance is observed in both AC as well as DC characteristics of these devices. The category of such devices includes field effect as well as bipolar families. Speed performance in some based circuits has reached limits previously dominated by III-V heterostructures based devices. In addition, for some optoelectronics applications including photodetectors it is now possible to easily integrate strained-Si1 xGex based optical devices into standard Silicon technology. The impact of integrating strained and relaxed Si1 xGex alloys into Si technology is important. It has lead to stimulate Si research as well as offers easy options for performances that requires very complicated and costly process if pure Si has to be used. In this paper we start by discussing the strain and stability of Si1 xGex alloys. The origin and the process responsible for transient enhanced diffusion (TED) in highly doped Si containing layers will be mentioned. Due to the importance of TED for thin highly doped Boron strained-Si1 xGex layers and its degrading consequences, possible suppression design methods will be presented. Quantum well pchannel MOSFETs (QW-PMOSFETs) based on thin buried QW are solution to the low speed and weak current derivability. Different aspects of designing these devices for a better performance are briefly reviewed. Other FETs based on tensile strained Si on relaxed Si1 xGex for n-channel and modulation doped field effect transistors (MODFETs) showed excellent performance. Record AC performance well above 200GHz for fmax is already observed and this record is expected to increase in the coming years. Heterojunction bipolar transistors (HPTs) with thin strained-Si1 xGex highly doped base have lead to optimize the performance of the bipolar technology for many applications easily. The strategies of design

  4. On strain and stress in living cells

    Science.gov (United States)

    Cox, Brian N.; Smith, David W.

    2014-11-01

    Recent theoretical simulations of amelogenesis and network formation and new, simple analyses of the basic multicellular unit (BMU) allow estimation of the order of magnitude of the strain energy density in populations of living cells in their natural environment. A similar simple calculation translates recent measurements of the force-displacement relation for contacting cells (cell-cell adhesion energy) into equivalent volume energy densities, which are formed by averaging the changes in contact energy caused by a cell's migration over the cell's volume. The rates of change of these mechanical energy densities (energy density rates) are then compared to the order of magnitude of the metabolic activity of a cell, expressed as a rate of production of metabolic energy per unit volume. The mechanical energy density rates are 4-5 orders of magnitude smaller than the metabolic energy density rate in amelogenesis or bone remodeling in the BMU, which involve modest cell migration velocities, and 2-3 orders of magnitude smaller for innervation of the gut or angiogenesis, where migration rates are among the highest for all cell types. For representative cell-cell adhesion gradients, the mechanical energy density rate is 6 orders of magnitude smaller than the metabolic energy density rate. The results call into question the validity of using simple constitutive laws to represent living cells. They also imply that cells need not migrate as inanimate objects of gradients in an energy field, but are better regarded as self-powered automata that may elect to be guided by such gradients or move otherwise. Thus Ġel=d/dt 1/2 >[(C11+C12)ɛ02+2μγ02]=(C11+C12)ɛ0ɛ˙0+2μγ0γ˙0 or Ġel=ηEɛ0ɛ˙0+η‧Eγ0γ˙0 with 1.4≤η≤3.4 and 0.7≤η‧≤0.8 for Poisson's ratio in the range 0.2≤ν≤0.4 and η=1.95 and η‧=0.75 for ν=0.3. The spatial distribution of shear strains arising within an individual cell as cells slide past one another during amelogenesis is not known

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

    Directory of Open Access Journals (Sweden)

    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.

  6. Strain rate effects for spallation of concrete

    Directory of Open Access Journals (Sweden)

    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].

  7. Pheromonal divergence between two strains of Spodoptera frugiperda.

    Science.gov (United States)

    Unbehend, Melanie; Hänniger, Sabine; Meagher, Robert L; Heckel, David G; Groot, Astrid T

    2013-03-01

    Spodoptera frugiperda consists of two genetically and behaviorally different strains, the corn- and the rice-strain, which seem to be in the process of sympatric speciation. We investigated the role of strain-specific sexual communication as a prezygotic mating barrier between both strains by analyzing strain-specific variation in female pheromone composition of laboratory and field strains, and also male attraction in wind tunnel and field experiments. Laboratory-reared and field-collected females from Florida exhibited strain-specific differences in their relative amount of (Z)-7-dodecenyl acetate (Z7-12:OAc) and (Z)-9-dodecenyl acetate (Z9-12:OAc). In wind tunnel assays, we did not find strain-specific attraction of males to females. However, in field experiments in Florida, we observed some differential attraction to synthetic pheromone blends. In a corn field, the corn-strain blend attracted more males of both strains than the rice-strain blend, but both blends were equally attractive in a grass field. Thus, habitat-specific volatiles seemed to influence male attraction to pheromones. In dose-response experiments, corn-strain males were more attracted to 2 % Z7-12:OAc than other doses tested, while rice-strain males were attracted to a broader range of Z7-12:OAc (2-10 %). The attraction of corn-strain males to the lowest dose of Z7-12:OAc corresponds to the production of this compound by females; corn-strain females produced significantly smaller amounts of Z7-12:OAc than rice-strain females. Although corn-strain individuals are more restricted in their production of and response to pheromones than rice-strain individuals, it seems that differences in sexual communication between corn- and rice-strain individuals are not strong enough to cause assortative mating.

  8. Transcriptomics and adaptive genomics of the asymptomatic bacteriuria Escherichia coli strain 83972

    DEFF Research Database (Denmark)

    Hancock, Viktoria; Seshasayee, Aswin S.; Ussery, David

    2008-01-01

    Escherichia coli strains are the major cause of urinary tract infections in humans. Such strains can be divided into virulent, UPEC strains causing symptomatic infections, and asymptomatic, commensal-like strains causing asymptomatic bacteriuria, ABU. The best-characterized ABU strain is strain....... Strain 83972 is a deconstructed pathogen rather than a commensal strain that has acquired fitness properties....

  9. METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS STRAINS IN FOOD AND ANIMAL

    Directory of Open Access Journals (Sweden)

    A. Traversa

    2010-03-01

    Full Text Available Some authors reported the possibility of a methicillin-resistant Staphylococcus aureus (MRSA human infections from meat and dairy products and methicillin-resistant Staphylococcus intermedius isolation in animals. The aim of this study is to investigate the methicillin-resistance in S. aureus strains and in S. intermedius strains (food and wild animals. 236 S.aureus strains from food, 36 S.aureus strains and 1 S. intermedius strain from wild animals were analyzed. 2 (0.74% MRSA strains from bovine milk were phenotipically resistant to cefoxitin, grew on chromogenic medium (MRSA Brilliance Oxoid and were mecA positive. All MRSA strains had the spa-type t899. All mecA positive strains showed at least resistance to eight of the antibiotics tested but none to glicopeptides. Both MRSA strains were enterotoxigenic.

  10. Influences of misfit strains on liquid phase heteroepitaxial growth

    Science.gov (United States)

    Lu, Yanli; Peng, Yingying; Yu, Genggeng; Chen, Zheng

    2017-10-01

    Influences of misfit strains with different signs on liquid phase heteroepitaxial growth are studied by binary phase field crystal model. It is amazing to find that double islands are formed because of lateral and vertical separation. The morphological evolution of epitaxial layer depends on signs of misfit strains. The maximum atomic layer thickness of double islands under negative misfit strain is larger than that of under positive misfit strain at the same evolutional time, and size differences between light and dark islands is much smaller under negative misfit strain than that of under positive misfit strain. In addition, concentration field and density field approximately have similar variational law along x direction under the same misfit strain but show opposite variational trend under misfit strains with different signs. Generally, free energy of epitaxial growth systems keeps similar variational trend under misfit strains with different signs.

  11. The evolution of strain path in cold wire drawing

    Science.gov (United States)

    Zhao, Tianzhang; Zhang, Guang-Liang; Zhang, Shi-Hong; Cheng, Ming; Song, Hong-Wu

    2013-05-01

    Evidence shows that the strain path significantly influences the subsequent material mechanical behaviors, while the strain path effect is neglected in the classical material models. In order to study the influence of strain path on wire property and establish a more accurate material model that will take strain path effects into consideration for improving drawn-wire production, the evolution of strain path must be investigated in cold wire drawing. In this article, three typical models for the expression of strain path change (SPC), which are written by strain rate, strain and stress deviator, respectively, are discussed. Mechanisms of strain path evolution in wire drawing, and the effect of die angle and reduction rate on SPC are investigated via finite element modeling.

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

    Directory of Open Access Journals (Sweden)

    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

  13. Spacecraft Dynamic Characterization by Strain Energies Method

    Science.gov (United States)

    Bretagne, J.-M.; Fragnito, M.; Massier, S.

    2002-01-01

    In the last years the significant increase in satellite broadcasting demand, with the wide band communication dawn, has given a great impulse to the telecommunication satellite market. The big demand is translated from operators (such as SES/Astra, Eutelsat, Intelsat, Inmarsat, EuroSkyWay etc.) in an increase of orders of telecom satellite to the world industrials. The largest part of these telecom satellite orders consists of Geostationary platforms which grow more and more in mass (over 5 tons) due to an ever longer demanded lifetime (up to 20 years), and become more complex due to the need of implementing an ever larger number of repeaters, antenna reflectors and feeds, etc... In this frame, the mechanical design and verification of these large spacecraft become difficult and ambitious at the same time, driven by the dry mass limitation objective. By the Finite Element Method (FEM), and on the basis of the telecom satellite heritage of a world leader constructor such as Alcatel Space Industries it is nowadays possible to model these spacecraft in a realistic and confident way in order to identify the main global dynamic aspects such as mode shapes, mass participation and/or dynamic responses. But on the other hand, one of the main aims consists in identifying soon in a program the most critical aspects of the system behavior in the launch dynamic environment, such as possible dynamic coupling between the different subsystems and secondary structures of the spacecraft (large deployable reflectors, thrusters, etc.). To this aim a numerical method has been developed in the frame of the Alcatel SPACEBUS family program, using MSC/Nastran capabilities and it is presented in this paper. The method is based on Spacecraft sub-structuring and strain energy calculation. The method mainly consists of two steps : 1) subsystem modal strain energy ratio (with respect to the global strain energy); 2) subsystem strain energy calculation for each mode according to the base driven

  14. Development of quantitative PCR and metagenomics-based approaches for strain quantification of a defined mixed-strain starter culture.

    Science.gov (United States)

    Johansen, Pernille; Vindeløv, Jannik; Arneborg, Nils; Brockmann, Elke

    2014-05-01

    Although the strain composition of mixed cultures may hugely affect production of various fermented foods, such as e.g. cheese, tools for investigating it have so far been limited. In this study, two new approaches for quantification of seven Lactococcus lactis subsp. cremoris strains (S1-S7) in a defined mixed-strain starter culture were developed and verified. By mapping NGS reads from 47 sequenced L. lactis strains to de novo assembly contigs of the seven strains, two strain-specific sequence regions (SEQ1 and SEQ2) were identified for each strain for qPCR primer design (A1 and A2). The qPCR assays amplified their strain-specific sequence region target efficiently. Additionally, high reproducibility was obtained in a validation sample containing equal amounts of the seven strains, and assay-to-assay coefficients of variance (CVs) for six (i.e. S1, S2, S4-S7) of the seven strains correlated to the inter-plate CVs. Hence, at least for six strains, the qPCR assay design approach was successful. The metagenomics-based approach quantified the seven strains based on average coverage of SEQ1 and SEQ2 by mapping sequencing reads from the validation sample to the strain-specific sequence regions. Average coverages of the SEQ1 and SEQ2 in the metagenomics data showed CVs of ≤17.3% for six strains (i.e. S1-S4, S6, S7). Thus, the metagenomics-based quantification approach was considered successful for six strains, regardless of the strain-specific sequence region used. When comparing qPCR- and metagenomics-based quantifications of the validation sample, the identified strain-specific sequence regions were considered suitable and applicable for quantification at a strain level of defined mixed-strain starter cultures.

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

    NARCIS (Netherlands)

    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

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

    Science.gov (United States)

    Kaufman, Joanne M

    2009-09-01

    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, the experience of serious strain, emotionally and behaviorally, is gendered. Depressive symptoms are particularly important for all types of deviance by females. Including multiple types of deviant outcomes offers a fuller understanding of both similarities and differences by gender. These results support the utility of GST as a theory of deviance in general and support greater connections between GST, feminist theorizing, and the sociology of mental health.

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

    DEFF Research Database (Denmark)

    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...... of one strain (PCR ribotype) per animal species per laboratory. Results: Altogether 112 isolates were collected and distributed into 38 PCR ribotypes with agarose based approach and 50 PCR ribotypes with sequencer based approach. Four PCR ribotypes were most prevalent in terms of number of isolates...... 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....

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

    NARCIS (Netherlands)

    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

  19. Brucella abortus Strain 2308 Wisconsin Genome: Importance of the Definition of Reference Strains.

    Science.gov (United States)

    Suárez-Esquivel, Marcela; Ruiz-Villalobos, Nazareth; Castillo-Zeledón, Amanda; Jiménez-Rojas, César; Roop Ii, R Martin; Comerci, Diego J; Barquero-Calvo, Elías; Chacón-Díaz, Carlos; Caswell, Clayton C; Baker, Kate S; Chaves-Olarte, Esteban; Thomson, Nicholas R; Moreno, Edgardo; Letesson, Jean J; De Bolle, Xavier; Guzmán-Verri, Caterina

    2016-01-01

    Brucellosis is a bacterial infectious disease affecting a wide range of mammals and a neglected zoonosis caused by species of the genetically homogenous genus Brucella. As in most studies on bacterial diseases, research in brucellosis is carried out by using reference strains as canonical models to understand the mechanisms underlying host pathogen interactions. We performed whole genome sequencing analysis of the reference strain B. abortus 2308 routinely used in our laboratory, including manual curated annotation accessible as an editable version through a link at https://en.wikipedia.org/wiki/Brucella#Genomics. Comparison of this genome with two publically available 2308 genomes showed significant differences, particularly indels related to insertional elements, suggesting variability related to the transposition of these elements within the same strain. Considering the outcome of high resolution genomic techniques in the bacteriology field, the conventional concept of strain definition needs to be revised.

  20. Brucella abortus Strain 2308 Wisconsin Genome: Importance of the Definition of Reference Strains

    Science.gov (United States)

    Suárez-Esquivel, Marcela; Ruiz-Villalobos, Nazareth; Castillo-Zeledón, Amanda; Jiménez-Rojas, César; Roop II, R. Martin; Comerci, Diego J.; Barquero-Calvo, Elías; Chacón-Díaz, Carlos; Caswell, Clayton C.; Baker, Kate S.; Chaves-Olarte, Esteban; Thomson, Nicholas R.; Moreno, Edgardo; Letesson, Jean J.; De Bolle, Xavier; Guzmán-Verri, Caterina

    2016-01-01

    Brucellosis is a bacterial infectious disease affecting a wide range of mammals and a neglected zoonosis caused by species of the genetically homogenous genus Brucella. As in most studies on bacterial diseases, research in brucellosis is carried out by using reference strains as canonical models to understand the mechanisms underlying host pathogen interactions. We performed whole genome sequencing analysis of the reference strain B. abortus 2308 routinely used in our laboratory, including manual curated annotation accessible as an editable version through a link at https://en.wikipedia.org/wiki/Brucella#Genomics. Comparison of this genome with two publically available 2308 genomes showed significant differences, particularly indels related to insertional elements, suggesting variability related to the transposition of these elements within the same strain. Considering the outcome of high resolution genomic techniques in the bacteriology field, the conventional concept of strain definition needs to be revised. PMID:27746773

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

    NARCIS (Netherlands)

    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

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

    Directory of Open Access Journals (Sweden)

    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

  3. High temperature static strain measurement with an electrical resistance strain gage

    Science.gov (United States)

    Lei, Jih-Fen

    1992-01-01

    An electrical resistance strain gage that can supply accurate static strain measurement for NASP application is being developed both in thin film and fine wire forms. This gage is designed to compensate for temperature effects on substrate materials with a wide range of thermal expansion coefficients. Some experimental results of the wire gage tested on one of the NASP structure materials, i.e., titanium matrix composites, are presented.

  4. Generating strain signals under consideration of road surface profiles

    Science.gov (United States)

    Putra, T. E.; Abdullah, S.; Schramm, D.; Nuawi, M. Z.; Bruckmann, T.

    2015-08-01

    The current study aimed to develop the mechanism for generating strain signal utilising computer-based simulation. The strain data, caused by the acceleration, were undertaken from a fatigue data acquisition involving car movements. Using a mathematical model, the measured strain signals yielded to acceleration data used to describe the bumpiness of road surfaces. The acceleration signals were considered as an external disturbance on generating strain signals. Based on this comparison, both the actual and simulated strain data have similar pattern. The results are expected to provide new knowledge to generate a strain signal via a simulation.

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

    KAUST Repository

    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.

  6. Towards a metabolic engineering strain "commons": an Escherichia coli platform strain for ethanol production.

    Science.gov (United States)

    Woodruff, Lauren B A; May, Brian L; Warner, Joseph R; Gill, Ryan T

    2013-05-01

    In the genome-engineering era, it is increasingly important that researchers have access to a common set of platform strains that can serve as debugged production chassis and the basis for applying new metabolic engineering strategies for modeling and characterizing flux, engineering complex traits, and optimizing overall performance. Here, we describe such a platform strain of E. coli engineered for ethanol production. Starting with a fully characterized host strain (BW25113), we site-specifically integrated the genes required for homoethanol production under the control of a strong inducible promoter into the genome and deleted the genes encoding four enzymes from competing pathways. This strain is capable of producing >30 g/L of ethanol in minimal media with production or tolerance was lost when grown under production conditions. Thus, our findings reinforce the need for a metabolic engineering "commons" that could provide a set of platform strains for use in more sophisticated genome-engineering strategies. Towards this end, we have made this production strain available to the scientific community.

  7. Stress-strain characteristics of materials at high strain rates. Part II. Experimental results

    Energy Technology Data Exchange (ETDEWEB)

    Ripperger, E. A. [Texas. Univ., Austin, TX (US). Structural Mechanics Research Lab.

    1958-08-29

    These two reports were issued separately, but are cataloged as a unit. A photoelectric method for measuring displacements during high-velocity impacts is described. The theory of the system is discussed in detail, and a prototype system which was built and tested is described. The performance of the prototype system is evaluated by comparing the results which it gives with results obtained by other methods of measurement. The system was found capable of a resolution of at least 0.01 inches. static and dynamic stress-strain characteristics of seven high polymers, polyethylene, teflon, nylon, tenite M, tenite H, polystyrene, and saran, plus three metals, lead, copper, and aluminum, are described and compared by means of stress-strain curves and photographs. Data are also presented which show qualitatively the effects produced on stress-strain characteristics by specimen configuration, temperature, and impact velocity. It is shown that there is a definite strain-rate effect for all these materials except polystyrene. The effect is one of an apparent stiffening of the material with increasing strain rate, which is similar to the effect produced by lowering the temperature. The stress-strain measurements are examined critically, inconsistencies are pointed out, and possible sources of error suggested. Values of yield stress, modulus of elasticity and energy absorption for all materials (except copper and aluminum), specimen configurations, temperatures, and impact velocities included in the investigation are tabulated.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  11. Ion beam studies in strained layer superlattices

    CERN Document Server

    Pathak, A P; Bhattacharya, D P; Dev, B N; Ghosh, S; Goswami, D K; Lakshmi-Bala, S; Nageswara-Rao, S V S; Satyam, P V; Siddiqui, A M; Srivastava, S K; Turos, A

    2002-01-01

    The potential device application of semiconductor heterostructures and strained layer superlattices has been highlighted. Metal organic chemical vapour deposition grown In sub 0 sub . sub 5 sub 3 Ga sub 0 sub . sub 4 sub 7 As/InP lattice-matched structure has been irradiated by 130 MeV Ag sup 1 sup 3 sup + and studied by RBS/Channelling using 3.5 MeV He sup 2 sup + ions. Ion irradiation seems to have induced a finite tensile strain in the InGaAs layer, indicating thereby that ion beam mixing occurs at this energy. Other complementary techniques like high resolution XRD and STM are needed to conclude the structural modifications in the sample.

  12. SNIT: SNP identification for strain typing

    Directory of Open Access Journals (Sweden)

    Reifman Jaques

    2011-09-01

    Full Text Available Abstract With ever-increasing numbers of microbial genomes being sequenced, efficient tools are needed to perform strain-level identification of any newly sequenced genome. Here, we present the SNP identification for strain typing (SNIT pipeline, a fast and accurate software system that compares a newly sequenced bacterial genome with other genomes of the same species to identify single nucleotide polymorphisms (SNPs and small insertions/deletions (indels. Based on this information, the pipeline analyzes the polymorphic loci present in all input genomes to identify the genome that has the fewest differences with the newly sequenced genome. Similarly, for each of the other genomes, SNIT identifies the input genome with the fewest differences. Results from five bacterial species show that the SNIT pipeline identifies the correct closest neighbor with 75% to 100% accuracy. The SNIT pipeline is available for download at http://www.bhsai.org/snit.html

  13. Chaotic desynchronization of multi-strain diseases

    CERN Document Server

    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.

  14. Modulating thermal conduction by the axial strain

    Science.gov (United States)

    Jiang, Jianjun; Zhao, Hong

    2016-09-01

    Recent studies have revealed that the symmetry of interparticle potential plays an important role in the one-dimensional thermal conduction problem. Here we demonstrate that, by introducing strain into the Fermi-Pasta-Ulam-β lattice, the interparticle potential can be converted from symmetric to asymmetric, which leads to a change of the asymptotic decaying behavior of the heat current autocorrelation function. More specifically, such a change in the symmetry of the potential induces a fast decaying stage, in which the heat current autocorrelation function decays faster than power-law manners or in a power-law manner but faster than ~t -1, in the transient stage. The duration of the fast decaying stage increases with increasing strain ratio and decreasing of the temperature. As a result, the thermal conductivity calculated following the Green-Kubo formula may show a truncation-time independent behavior, suggesting a system-size independent thermal conductivity.

  15. Transfer induced compressive strain in graphene

    DEFF Research Database (Denmark)

    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....

  16. A tunable strain sensor using nanogranular metals.

    Science.gov (United States)

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

    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. 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.

  17. A Tunable Strain Sensor Using Nanogranular Metals

    Directory of Open Access Journals (Sweden)

    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.

  18. A Tunable Strain Sensor Using Nanogranular Metals

    Science.gov (United States)

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

    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. 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. PMID:22163443

  19. Relation between job strain and myocardial infarction

    DEFF Research Database (Denmark)

    Netterstrøm, B; Nielsen, F E; Kristensen, T S;

    1999-01-01

    to hospital who were residents of the same county were used. Both groups were interviewed with an extensive questionnaire on job related conditions. Several indices on job related psychosocial factors were established in accordance with Karasek's job strain model as well as the extension of the model......OBJECTIVES: To study the influence of different job related and socioeconomic factors for development of myocardial infarction (MI). METHOD: The study was a case-control study of 76 male wage earners who had been admitted to hospital with MI. As a control group 176 male wage earners not admitted......, the isostrain model. RESULTS: The most significant findings were consistent with Karasek's job strain model in that mean with a high degree of demand combined with a low degree of control at work had a significantly increased odds ratio (OR) 95% confidence interval (95% CI) of 2.1 (1.2 to 3.8) for MI after...

  20. Organic chemistry. Strain-release amination.

    Science.gov (United States)

    Gianatassio, Ryan; Lopchuk, Justin M; Wang, Jie; Pan, Chung-Mao; Malins, Lara R; Prieto, Liher; Brandt, Thomas A; Collins, Michael R; Gallego, Gary M; Sach, Neal W; Spangler, Jillian E; Zhu, Huichin; Zhu, Jinjiang; Baran, Phil S

    2016-01-15

    To optimize drug candidates, modern medicinal chemists are increasingly turning to an unconventional structural motif: small, strained ring systems. However, the difficulty of introducing substituents such as bicyclo[1.1.1]pentanes, azetidines, or cyclobutanes often outweighs the challenge of synthesizing the parent scaffold itself. Thus, there is an urgent need for general methods to rapidly and directly append such groups onto core scaffolds. Here we report a general strategy to harness the embedded potential energy of effectively spring-loaded C-C and C-N bonds with the most oft-encountered nucleophiles in pharmaceutical chemistry, amines. Strain-release amination can diversify a range of substrates with a multitude of desirable bioisosteres at both the early and late stages of a synthesis. The technique has also been applied to peptide labeling and bioconjugation.

  1. Magnetic properties on strained manganite thin film

    Science.gov (United States)

    Prajapat, C. L.; Singh, M. R.; Gupta, S. K.; Bhattacharya, D.; Basu, S.; Ravikumar, G.

    2014-04-01

    Structural and magnetic studies on La2/3Sr1/3MnO3 (LSMO) epitaxial films grown on STO (100) and MgO (100) substrates by Pulsed Laser Deposition are presented. Due to larger interface strain, the grain size of LSMO on MgO is much smaller than that on STO substrate. However, anisotropy energy produced as a result of in plane tensile strain is much larger in case of the films deposited on MgO in such a way that the blocking (irreversibility) temperature and the coercive fields inferred from temperature and magnetic field dependent magnetization measurements are significantly higher. The importance of this result for the memory applications is highlighted.

  2. Dynamic strain aging in Haynes 282 superalloy

    Directory of Open Access Journals (Sweden)

    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.

  3. Raman-strain relations in highly strained Ge: Uniaxial ⟨100⟩, ⟨110⟩ and biaxial (001) stress

    Science.gov (United States)

    Gassenq, A.; Tardif, S.; Guilloy, K.; Duchemin, I.; Pauc, N.; Hartmann, J. M.; Rouchon, D.; Widiez, J.; Niquet, Y. M.; Milord, L.; Zabel, T.; Sigg, H.; Faist, J.; Chelnokov, A.; Rieutord, F.; Reboud, V.; Calvo, V.

    2017-02-01

    The application of high values of strain to Ge considerably improves its light emission properties and can even turn it into a direct band gap semiconductor. Raman spectroscopy is routinely used for strain measurements. Typical Raman-strain relationships that are used for Ge were defined up to ˜1% strain using phonon deformation potential theory. In this work, we have studied this relationship at higher strain levels by calculating and measuring the Raman spectral shift-strain relations in several different strain configurations. Since differences were shown between the usual phonon deformation potential theory and ab-initio calculations, we highlight the need for experimental calibrations. We have then measured the strain in highly strained Ge micro-bridges and micro-crosses using Raman spectroscopy performed in tandem with synchrotron based micro-diffraction. High values of strain are reported, which enable the calibration of the Raman-strain relations up to 1.8% of in plane strain for the (001) biaxial stress, 4.8% strain along ⟨100⟩, and 3.8% strain along ⟨110⟩. For Ge micro-bridges, oriented along ⟨100⟩, the nonlinearity of the Raman shift-strain relation is confirmed. For the ⟨110⟩ orientation, we have shown that an unexpected non-linearity in the Raman-strain relationship has also to be taken into account for high stress induction. This work demonstrates an unprecedented level of strain measurement for the ⟨110⟩ uniaxial stress and gives a better understanding of the Raman-strain relations in Ge.

  4. Systems strategies for developing industrial microbial strains

    DEFF Research Database (Denmark)

    Lee, Sang Yup; Kim, Hyun Uk

    2015-01-01

    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...... 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...

  5. Strain-specific chemotaxis of Azospirillum spp.

    OpenAIRE

    Reinhold, B; Hurek, T; Fendrik, I

    1985-01-01

    Chemotactic responses of three Azospirillum strains originating from different host plants were compared to examine the possible role of chemotaxis in the adaptation of these bacteria to their respective hosts. The chemotaxis to several sugars, amino acids, and organic acids was determined qualitatively by an agar plate assay and quantitatively by a channeled-chamber technique. High chemotactic ratios, up to 40, were obtained with the latter technique. The chemotactic response did not rely up...

  6. Cyclic Strain Enhances Cellular Uptake of Nanoparticles

    OpenAIRE

    Jia Hu; Yaling Liu

    2015-01-01

    Nanoparticles (NPs) have gained increasing interest in recent years due to their potential use as drug carrier, imaging, and diagnostic agents in pharmaceutical and biomedical applications. While many cells in vivo experience mechanical forces, little is known about the correlation of the mechanical stimulation and the internalization of NPs into cells. This paper investigates the effects of applied cyclic strain on NP uptake by cells. Bovine aortic endothelial cells (BAECs) were cultured on ...

  7. Gurson's Model: ALE Formulation and Strain Localization

    Science.gov (United States)

    da Cunda, Luiz A. B.; Creus, Guillermo J.

    2007-05-01

    This paper presents a brief review of Gurson's damage model, employed to describes the strength degradation in ductile metals submitted to large plastic deformations. The damage model is applied using finite elements and an Arbitrary Lagrangian-Eulerian formulation (ALE), to ensure a better quality to the finite elements mesh. The study of the combined application of ALE and Gurson approach to damage modeling and strain localization is the object of this paper.

  8. PNNL Stress/Strain Correlation for Zircaloy

    Energy Technology Data Exchange (ETDEWEB)

    Geelhood, Kenneth J.; Beyer, Carl E.; Luscher, Walter G.

    2008-07-18

    Pacific Northwest National Laboratory (PNNL) was tasked with incorporating cladding mechanical property data into the Nuclear Regulatory Commission (NRC) fuel codes, FRAPCON-31 and FRAPTRAN2, by the NRC Office of Nuclear Reactor Research. The objective of that task was to create a mechanical model that can calculate true stress, true strain, and the possible failure of the fuel rod cladding based on uniaxial test data.

  9. Achebe, Conrad, and the Postcolonial Strain

    OpenAIRE

    2008-01-01

    In his article "Achebe, Conrad, and the Postcolonial Strain" Eric Sipyinyu Njeng presents an analysis of Chinua Achebe's Things Fall Apart in a context of postcolonial thought and argues that while Achebe's text is often placed against Joseph Conrad's Heart of Darkness as a counter discourse -- thus interrogating Conrad's portraiture of Africans as savages -- Achebe's text in fact represents anti-Africanism and subservience to Occidental values. Examining Achebe's authorial intention in Thing...

  10. Quasi-bound states in strained graphene

    Science.gov (United States)

    Bahamon, Dario; Qi, Zenan; Park, Harold; Pareira, Vitor; Campbell, David

    In this work, we explore the possibility of manipulating electronic states in graphene nanostructures by mechanical means. Specifically, we use molecular dynamics and tight-binding models to access the electronic and transport properties of strained graphene nanobubbles and graphene kirigami. We establish that low energy electrons can be confined in the arms of the kirigami and within the nanobubbles; under different load conditions the coupling between confined states and continuous states is modified creating different conductance line-shapes.

  11. Models for elastic shells with incompatible strains

    OpenAIRE

    2012-01-01

    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...

  12. Plane strain problem in microstretch elastic solid

    Indian Academy of Sciences (India)

    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.

  13. Characterization of urinary Escherichia coli O75 strains.

    Science.gov (United States)

    Nimmich, W; Voigt, W; Seltmann, G

    1997-01-01

    Forty-four Escherichia coli O75 strains from patients with urinary tract infections were characterized by a variety of methods to obtain evidence of their clonal distribution and uropathogenic properties. By K and H antigen typing, the strains were divided into the following serotypes: O75:K5:H- (18 strains), O75:K95:H- (10 strains), O75:K95:H5 (7 strains), O75:K100:H5 (4 strains), and O75:K-:H55 (5 strains). Generally, biotyping proved to be of no discriminative value. With two exceptions the strains were found to be sensitive to the bactericidal effect of normal human serum. As shown by multilocus enzyme electrophoresis, the whole-cell protein profile (WCPP), and the patterns of the outer membrane proteins and lipopolysaccharides, all but the five O75:H55 strains were genetically closely related to each other and could be classified into one clonal group. The O75:K-:H55 strains proved to be quite different and lacked type 1 fimbriae. All 17 K95 (H-, H5) strains produced hemolysin and P fimbriae. Five of the O75:K5:H- strains were different from the other K5 strains by showing hemagglutinating properties, on the basis of the presence of the OX adhesin. The last two groups are suggested to be uropathogenic and are proposed to represent separate clonal groups or subgroups. PMID:9114391

  14. Integrated strain array for cellular mechanobiology studies

    Science.gov (United States)

    Simmons, C. S.; Sim, J. Y.; Baechtold, P.; Gonzalez, A.; Chung, C.; Borghi, N.; Pruitt, B. L.

    2011-05-01

    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.

  15. MACROSCOPIC STRAIN POTENTIALS IN NONLINEAR POROUS MATERIALS

    Institute of Scientific and Technical Information of China (English)

    刘熠; 黄筑平

    2003-01-01

    By taking a hollow sphere as a representative volume element (RVE), the macroscopic strain potentials of porous materials with power-law incompressible matrix are studied in this paper.According to the principles of the minimum potential energy in nonlinear elasticity and the variational procedure, static admissible stress fields and kinematic admissible displacement fields are constructed,and hence the upper and the lower bounds of the macroscopic strain potential are obtained. The bounds given in the present paper differ so slightly that they both provide perfect approximations of the exact strain potential of the studied porous materials. It is also found that the upper bound proposed by previous authors is much higher than the present one, and the lower bounds given by Cocks is much lower. Moreover, the present calculation is also compared with the variational lower bound of Ponte Castafneda for statistically isotropic porous materials. Finally, the validity of the hollow spherical RVE for the studied nonlinear porous material is discussed by the difference between the present numerical results and the Cocks bound.

  16. STRESS AND STRAIN ANALYSIS AROUND UNDERGROUND ROOM

    Directory of Open Access Journals (Sweden)

    Krešimir Tor

    2000-12-01

    Full Text Available By excavation of opening in the rock, a stress concentration around the opening occurs. The state of stresses and strains around an opening is analysed by theory of elasticity and by Finite Element Method (FEM.The aim of the paper is to determine the dimension of the FEM model for the stress and strain analysis around an elliptical opening in rock massif. The numerical calculation have been performed for two different boundary conditions: with forces or with displacements. Boundary conditions given by displacements give better approximation in the state of stress and strains. An example of the excavation of a road tunnel is used to represent stress concentration at the opening and the places where the plastic zones occur. The computation has been done after FEM comprising the Hock-Brown criterion of failure. The results of stability analysis point to the zones where failure of the rock material may be anticipa¬ted. This is important when planning and designing the primary supp¬orts. The comparison of the results of numerical modelling and field recording during excavation is of particular significance (the paper is published in Croatian.

  17. Dislocation Multi-junctions and Strain Hardening

    Energy Technology Data Exchange (ETDEWEB)

    Bulatov, V; Hsiung, L; Tang, M; Arsenlis, A; Bartelt, M; Cai, W; Florando, J; Hiratani, M; Rhee, M; Hommes, G; Pierce, T; Diaz de la Rubia, T

    2006-06-20

    At the microscopic scale, the strength of a crystal derives from the motion, multiplication and interaction of distinctive line defects--dislocations. First theorized in 1934 to explain low magnitudes of crystal strength observed experimentally, the existence of dislocations was confirmed only two decades later. Much of the research in dislocation physics has since focused on dislocation interactions and their role in strain hardening: a common phenomenon in which continued deformation increases a crystal's strength. The existing theory relates strain hardening to pair-wise dislocation reactions in which two intersecting dislocations form junctions tying dislocations together. Here we report that interactions among three dislocations result in the formation of unusual elements of dislocation network topology, termed hereafter multi-junctions. The existence of multi-junctions is first predicted by Dislocation Dynamics (DD) and atomistic simulations and then confirmed by the transmission electron microscopy (TEM) experiments in single crystal molybdenum. In large-scale Dislocation Dynamics simulations, multi-junctions present very strong, nearly indestructible, obstacles to dislocation motion and furnish new sources for dislocation multiplication thereby playing an essential role in the evolution of dislocation microstructure and strength of deforming crystals. Simulation analyses conclude that multi-junctions are responsible for the strong orientation dependence of strain hardening in BCC crystals.

  18. Mycotoxin-degradation profile of Rhodococcus strains.

    Science.gov (United States)

    Cserháti, M; Kriszt, B; Krifaton, Cs; Szoboszlay, S; Háhn, J; Tóth, Sz; Nagy, I; Kukolya, J

    2013-08-16

    Mycotoxins are secondary fungal metabolites that may have mutagenic, carcinogenic, cytotoxic and endocrine disrupting effects. These substances frequently contaminate agricultural commodities despite efforts to prevent them, so successful detoxification tools are needed. The application of microorganisms to biodegrade mycotoxins is a novel strategy that shows potential for application in food and feed processing. In this study we investigated the mycotoxin degradation ability of thirty-two Rhodococcus strains on economically important mycotoxins: aflatoxin B1, zearalenone, fumonisin B1, T2 toxin and ochratoxin A, and monitored the safety of aflatoxin B1 and zearalenone degradation processes and degradation products using previously developed toxicity profiling methods. Moreover, experiments were performed to analyse multi-mycotoxin-degrading ability of the best toxin degrader/detoxifier strains on aflatoxin B1, zearalenone and T2 toxin mixtures. This enabled the safest and the most effective Rhodococcus strains to be selected, even for multi-mycotoxin degradation. We concluded that several Rhodococcus species are effective in the degradation of aromatic mycotoxins and their application in mycotoxin biodetoxification processes is a promising field of biotechnology.

  19. Cylindrical shell buckling through strain hardening

    Energy Technology Data Exchange (ETDEWEB)

    Bandyopadhyay, K.; Xu, J.; Shteyngart, S. [Brookhaven National Lab., Upton, NY (United States); Gupta, D. [USDOE, Germantown, MD (United States)

    1995-04-01

    Recently, the authors published results of plastic buckling analysis of cylindrical shells. Ideal elastic-plastic material behavior was used for the analysis. Subsequently, the buckling analysis program was continued with the realistic stress-strain relationship of a stainless steel alloy which does not exhibit a clear yield point. The plastic buckling analysis was carried out through the initial stages of strain hardening for various internal pressure values. The computer program BOSOR5 was used for this purpose. Results were compared with those obtained from the idealized elastic-plastic relationship using the offset stress level at 0.2% strain as the yield stress. For moderate hoop stress values, the realistic stress-grain case shows a slight reduction of the buckling strength. But, a substantial gain in the buckling strength is observed as the hoop stress approaches the yield strength. Most importantly, the shell retains a residual strength to carry a small amount of axial compressive load even when the hoop stress has exceeded the offset yield strength.

  20. Strain Functionals for Characterizing Atomistic Geometries

    Science.gov (United States)

    Kober, Edward; Rudin, Sven

    The development of a set of strain tensor functionals that are capable of characterizing arbitrarily ordered atomistic structures is described. This approach defines a Gaussian-weighted neighborhood around each atom and characterizes that local geometry in terms of n-th order strain tensors, which are equivalent to the moments of the neighborhood. Fourth order expansions can distinguish the cubic structures (and deformations thereof), but sixth order expansions are required to fully characterize hexagonal structures. Other methods used to characterize atomic structures, such as the Steinhardt parameters or the centrosymmetry metric, can be derived from this more general approach. These functions are continuous and smooth and much less sensitive to thermal fluctuations than other descriptors based on discrete neighborhoods. They allow material phases, deformations, and a large number of defect structures to be readily identified and classified. Applications to the analysis of shock-loaded samples of Cu, Ta and Ti will be presented. This strain functional basis can also then be used for developing interatomic potential functions, and an initial application to Cu will be presented.

  1. Sorbitol production using recombinant Zymomonas mobilis strain.

    Science.gov (United States)

    Liu, Changjun; Dong, Hongwei; Zhong, Jianjiang; Ryu, Dewey D Y; Bao, Jie

    2010-07-20

    A recombinant Zymomonas mobilis strain harboring the plasmid pHW20a-gfo for over-expression of glucose-fructose oxidoreductase (GFOR) was constructed. The specific activity of GFOR enzyme in the new recombinant strain was at least two folds greater than that in the wild strain. The maximum GFOR activity achieved in terms of the volumetric, and the cellular were 2.59 U ml(-1), and 0.70 U mg(-1), respectively, in the batch cultures. A significant improvement of the bioconversion process for the production of sorbitol and gluconic acid from glucose and fructose was made using divalent metal ions which drastically reduced the ethanol yield and significantly increased the yield of target product. Among several divalent metal ions evaluated, Zn(2+) was found to be most effective by inhibiting the Entner-Doudoroff pathway enzymes. The yield of the byproduct ethanol was reduced from 16.7 to 1.8 gl(-1) and the sorbitol yield was increased to almost 100% from 89%. The Ca(2+) enhanced the sorbitol yield and the formation of calcium gluconate salt made the separation of gluconate from the reaction system easier.

  2. Enterobacter Strains Might Promote Colon Cancer.

    Science.gov (United States)

    Yurdakul, Dilşad; Yazgan-Karataş, Ayten; Şahin, Fikrettin

    2015-09-01

    Many studies have been performed to determine the interaction between bacterial species and cancer. However, there has been no attempts to demonstrate a possible relationship between Enterobacter spp. and colon cancer so far. Therefore, in the present study, it is aimed to investigate the effects of Enterobacter strains on colon cancer. Bacterial proteins were isolated from 11 Enterobacter spp., one Morganella morganii, and one Escherichia coli strains, and applied onto NCM460 (Incell) and CRL1790 (ATCC) cell lines. Cell viability and proliferation were determined in MTS assay. Flow Cytometry was used to detect CD24 level and apoptosis. Real-Time PCR studies were performed to determine NFKB and Bcl2 expression. Graphpad Software was used for statistical analysis. The results showed that proteins, isolated from the Enterobacter spp., have significantly increased cell viability and proliferation, while decreasing the apoptosis of the cell lines tested. The data in the present study indicated that Enterobacter strains might promote colon cancer. Moreover, Enterobacter spp. could be a clinically important factor for colon cancer initiation and progression. Studies can be extended on animal models in order to develop new strategies for treatment.

  3. Shewanella strain isolated from black powder

    Energy Technology Data Exchange (ETDEWEB)

    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)

  4. Techniques for increasing boron fiber fracture strain

    Science.gov (United States)

    Dicarlo, J. A.

    1977-01-01

    Improvement in the strain-to-failure of chemical-vapor-deposition boron fibers is shown possible by contracting the tungsten boride core region and its inherent flaws. Results of three methods are presented in which etching and thermal-processing techniques were employed to achieve core flaw contraction by internal stresses available in the boron sheath. After commercially and treatment-induced surface flaws were removed from 203-micron (8-mil) fibers, the core flaw was observed to be essentially the only source of fiber fracture. Thus, fiber strain-to-failure was found to improve by an amount equal to the treatment-induced contraction on the core flaw. To date, average fracture strains and stresses greater than 1.4% and 5.5 GN/sq m (800 ksi), respectively, have been achieved. Commercial feasibility considerations suggest as the most cost-effective technique that method in which as-produced fibers are given a rapid heat treatment above 700 C. Preliminary results concerning the contraction kinetics and fracture behavior observed with this technique are presented and discussed for both high-vacuum and argon-gas heat-treatment environments.

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

    Energy Technology Data Exchange (ETDEWEB)

    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. Spatial Compressive Sensing for Strain Data Reconstruction from Sparse Sensors

    Science.gov (United States)

    2014-10-01

    Spatial Compressive Sensing for Strain Data Reconstruction from Sparse Sensors by Mulugeta A Haile ARL-TR-7126 October 2014...Spatial Compressive Sensing for Strain Data Reconstruction from Sparse Sensors Mulugeta A Haile Vehicle Technology Directorate, ARL...

  7. Bird Flu Strain May Have Jumped from Cat to Human

    Science.gov (United States)

    ... page: https://medlineplus.gov/news/fullstory_162717.html Bird Flu Strain May Have Jumped From Cat to ... would be the first known transmission of this bird flu strain from cat to human, officials said. ...

  8. Strains and stressors: an analysis of touchscreen learning in genetically diverse mouse strains.

    Directory of Open Access Journals (Sweden)

    Carolyn Graybeal

    Full Text Available Touchscreen-based systems are growing in popularity as a tractable, translational approach for studying learning and cognition in rodents. However, while mouse strains are well known to differ in learning across various settings, performance variation between strains in touchscreen learning has not been well described. The selection of appropriate genetic strains and backgrounds is critical to the design of touchscreen-based studies and provides a basis for elucidating genetic factors moderating behavior. Here we provide a quantitative foundation for visual discrimination and reversal learning using touchscreen assays across a total of 35 genotypes. We found significant differences in operant performance and learning, including faster reversal learning in DBA/2J compared to C57BL/6J mice. We then assessed DBA/2J and C57BL/6J for differential sensitivity to an environmental insult by testing for alterations in reversal learning following exposure to repeated swim stress. Stress facilitated reversal learning (selectively during the late stage of reversal in C57BL/6J, but did not affect learning in DBA/2J. To dissect genetic factors underlying these differences, we phenotyped a family of 27 BXD strains generated by crossing C57BL/6J and DBA/2J. There was marked variation in discrimination, reversal and extinction learning across the BXD strains, suggesting this task may be useful for identifying underlying genetic differences. Moreover, different measures of touchscreen learning were only modestly correlated in the BXD strains, indicating that these processes are comparatively independent at both genetic and phenotypic levels. Finally, we examined the behavioral structure of learning via principal component analysis of the current data, plus an archival dataset, totaling 765 mice. This revealed 5 independent factors suggestive of "reversal learning," "motivation-related late reversal learning," "discrimination learning," "speed to respond," and

  9. Strains and stressors: an analysis of touchscreen learning in genetically diverse mouse strains.

    Science.gov (United States)

    Graybeal, Carolyn; Bachu, Munisa; Mozhui, Khyobeni; Saksida, Lisa M; Bussey, Timothy J; Sagalyn, Erica; Williams, Robert W; Holmes, Andrew

    2014-01-01

    Touchscreen-based systems are growing in popularity as a tractable, translational approach for studying learning and cognition in rodents. However, while mouse strains are well known to differ in learning across various settings, performance variation between strains in touchscreen learning has not been well described. The selection of appropriate genetic strains and backgrounds is critical to the design of touchscreen-based studies and provides a basis for elucidating genetic factors moderating behavior. Here we provide a quantitative foundation for visual discrimination and reversal learning using touchscreen assays across a total of 35 genotypes. We found significant differences in operant performance and learning, including faster reversal learning in DBA/2J compared to C57BL/6J mice. We then assessed DBA/2J and C57BL/6J for differential sensitivity to an environmental insult by testing for alterations in reversal learning following exposure to repeated swim stress. Stress facilitated reversal learning (selectively during the late stage of reversal) in C57BL/6J, but did not affect learning in DBA/2J. To dissect genetic factors underlying these differences, we phenotyped a family of 27 BXD strains generated by crossing C57BL/6J and DBA/2J. There was marked variation in discrimination, reversal and extinction learning across the BXD strains, suggesting this task may be useful for identifying underlying genetic differences. Moreover, different measures of touchscreen learning were only modestly correlated in the BXD strains, indicating that these processes are comparatively independent at both genetic and phenotypic levels. Finally, we examined the behavioral structure of learning via principal component analysis of the current data, plus an archival dataset, totaling 765 mice. This revealed 5 independent factors suggestive of "reversal learning," "motivation-related late reversal learning," "discrimination learning," "speed to respond," and "motivation during

  10. A biogeochemical model of Lake Pusiano (North Italy and its use in the predictability of phytoplankton blooms: first preliminary results

    Directory of Open Access Journals (Sweden)

    Alessandro OGGIONI

    2006-02-01

    Full Text Available This study reports the first preliminary results of the DYRESM-CAEDYM model application to a mid size sub-alpine lake (Lake Pusiano North Italy. The in-lake modelling is a part of a more general project called Pusiano Integrated Lake/Catchment project (PILE whose final goal is to understand the hydrological and trophic relationship between lake and catchment, supporting the restoration plan of the lake through field data analysis and numerical models. DYRESM is a 1D-3D hydrodynamics model for predicting the vertical profile of temperature, salinity and density. CAEDYM is multi-component ecological model, used here as a phytoplankton-zooplankton processes based model, which includes algorithms to simulate the nutrient cycles within the water column as well as the air-water gas exchanges and the water-sediments fluxes. The first results of the hydrodynamics simulations underline the capability of the model to accurately simulate the surface temperature seasonal trend and the thermal gradient whereas, during summer stratification, the model underestimates the bottom temperature of around 2 °C. The ecological model describes the epilimnetic reactive phosphorus (PO4 depletion (due to the phytoplankton uptake and the increase in PO4 concentrations in the deepest layers of the lake (due to the mineralization processes and the sediments release. In terms of phytoplankton dynamics the model accounts for the Planktothrix rubescens dominance during the whole season, whereas it seems to underestimate the peak in primary production related to both the simulated algal groups (P. rubescens and the rest of the other species aggregated in a single class. The future aims of the project are to complete the model parameterization and to connect the in-lake and the catchment modelling in order to gain an integrated view of the lake-catchment ecosystem as well as to develop a three dimensional model of the lake.

  11. Distribution of Longitudinal Inherent Strains in Multiple-passes Welding

    Institute of Scientific and Technical Information of China (English)

    Peng HE; Jiuhai ZHANG; Toshio Terasaki; Testuya Akiyama

    2001-01-01

    A fundamental theory for the analysis of residual welding stresses and deformation based on the inherent strain distribution along the welded joint is introduced. The computing method of distribution of longitudinal inherent strains in multiple-passes welding in heavy plate weldment is proposed. Distribution of longitudinal inherent strains in one-pass welding and two-passes welding are compared and analyzed. The effect of cutting on inherent strain is discussed.

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

    KAUST Repository

    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.

  13. EVALUATION OF LOCAL STRAIN EVOLUTION FROM METALLIC WHISKER FORMATION

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    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

  15. Base composition, size and sequence similarities of genoma deoxyribonucleic acids from clinical isolates of Pseudomonas putrefaciens.

    Science.gov (United States)

    Owen, R J; Legors, R M; Lapage, S P

    1978-01-01

    The mean base compositions of DNA from 27 strains of Pseudomonas putrefaciens, P. rubescens and P. piscicida ranged from 43-4 to 53-2 mol% GC with genome sizes from 3.04 X 10(9) to 4.23 X 10(9) daltons. On the basis of in vitro DNA-DNA binding, estimated spectrophotometrically from initial renaturation rates, P. putrefaciens strains were heterogenous in the extent to which they shared similar nucleotide sequences, and were divided into four DNA homology groups. The DNA characteristics of strains in these groups correlated with several biochemical characteristics that facilitated identification of clinical isolates of P. putrefaciens. The two species P. putrefaciens and P. rubescens appear to be synonymous and none of the four groups of P. putrefaciens was related in DNA sequences to P. pisicida. Pseudomonas putrefaciens should theretofore be retained as a single species and characteristics for identifying the various groups within the species are listed.

  16. Flexible Bond Wire Capacitive Strain Sensor for Vehicle Tyres

    Directory of Open Access Journals (Sweden)

    Siyang Cao

    2016-06-01

    Full Text Available 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.

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

    Institute of Scientific and Technical Information of China (English)

    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.

  18. Corrosion induced strain monitoring through fibre optic sensors

    Energy Technology Data Exchange (ETDEWEB)

    Grattan, S K T [School of Planning, Architecture and Civil Engineering, Queen' s University Belfast, David Keir Building, Belfast, BT9 5AG (United Kingdom); Basheer, P A M [School of Planning, Architecture and Civil Engineering, Queen' s University Belfast, David Keir Building, Belfast, BT9 5AG (United Kingdom); Taylor, S E [School of Planning, Architecture and Civil Engineering, Queen' s University Belfast, David Keir Building, Belfast, BT9 5AG (United Kingdom); Zhao, W [School of Engineering and Mathematical Sciences, City University, Northampton Square, London, EC1V 0HB (United Kingdom); Sun, T [School of Engineering and Mathematical Sciences, City University, Northampton Square, London, EC1V 0HB (United Kingdom); Grattan, K T V [School of Engineering and Mathematical Sciences, City University, Northampton Square, London, EC1V 0HB (United Kingdom)

    2007-10-15

    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.

  19. Complete Genome Sequence of Vaccinia Virus Strain L-IVP

    Science.gov (United States)

    Shvalov, Alexander N.; Sivolobova, Galina F.; Kuligina, Elena V.

    2016-01-01

    Most of the live vaccine doses of vaccinia virus donated to the Intensified Smallpox Eradication Programme after 1971 were prepared using the L-IVP strain. A mixture of three clones of the L-IVP strain was sequenced using MySEQ. Consensus sequence similarity with the vaccinia virus Lister strain is 99.5%. PMID:27174282

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

    NARCIS (Netherlands)

    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

  1. Identification of Trichoderma strains by image analysis of HPLC chromatograms

    DEFF Research Database (Denmark)

    Thrane, Ulf; Poulsen, S.B.; Nirenberg, H.I.

    2001-01-01

    Forty-four Trichoderma strains from water-damaged building materials or indoor dust were classified with chromatographic image analysis on full chromatographic matrices obtained by high performance liquid chromatography with UV detection of culture extracts. The classes were compared with morphol......Forty-four Trichoderma strains from water-damaged building materials or indoor dust were classified with chromatographic image analysis on full chromatographic matrices obtained by high performance liquid chromatography with UV detection of culture extracts. The classes were compared...... with morphological identification and rDNA sequence data, and for each class all strains were of the same identity. With all three techniques each strain - except one - was identified as the same species. These strains belonged to Trichoderma atroviride (nine strains), Trichoderma viride (three strains), Trichoderma...... harzianum (10 strains), Trichoderma citrinoviride (12 strains), and Trichoderma longibrachiatum (nine strains). The odd strain was identified as Trichoderma hamatum by morphology and rDNA sequencing. but not by image analysis as no reference strains of this species were included. It is concluded...

  2. MM98.83 Quantification of Combined Strain Paths

    DEFF Research Database (Denmark)

    Nielsen, Morten Sturgård; Lindegren, Maria; Wanheim, Tarras

    1998-01-01

    When working with processes where large plastic deformation occurs, a way of desribing the deformation process is to view the whole deformation history as a curve in the 6-dimensional shear strain normal strain space, henceforth called a strain history curve (SHC). This paper focuses on the SHC...

  3. Strain improvement of Gluconacetobacter xylinus NCIM 2526 for ...

    African Journals Online (AJOL)

    TUOYO

    2010-08-09

    Aug 9, 2010 ... wild strain. The mutant GHUV4 gave cellulose yield of 3.92 g/l which was 30% more than the wild strain ... One of the. BC application problems in industry is its low productivity. One approach to combat BC productivity is strain.

  4. Antimalarial effect of agmatine on Plasmodium berghei K173 strain

    Institute of Scientific and Technical Information of China (English)

    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.

  5. 40 CFR 721.9518 - Sinorhizobium meliloti strain RMBPC-2.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Sinorhizobium meliloti strain RMBPC-2... Substances § 721.9518 Sinorhizobium meliloti strain RMBPC-2. (a) Microorganism and significant new uses subject to reporting. (1) The microorganism identified as Sinorhizobium meliloti strain RMBPC-2 (PMN...

  6. Screening of flocculant-producing strains by NTG mutagenesis

    Institute of Scientific and Technical Information of China (English)

    HUANG Xiao-wu; CHENG Wen; HU Yong-you

    2005-01-01

    Screening of new microorganism being able to produce efficiently flocculants was carried out. A new model for screening efficient flocculant-producing strains was designed and tested. The results showed that this model for screening efficient flocculant-producing strains is very reliable and can greatly shorten the screening period. 13 flocculant-producing strains were isolated from activated sludge by conventional method. A strain, designated as HHE6, produced the bioflocculant with the turbidity removal 98% for kaolin suspension. Six of 13 strains selected as the original strains were treated with NTG as mutagen, and five mutant strains(HHE-P7, HHE-A8, HHE-P21,HHE-P24, HHE-A26) with high flocculation efficiency was obtained by selection, which exhibited the flocculation rate for kaolin suspension above 90%. Strains HHE6, HHE-P7, and HHE-P24 were classified as Penicillium purpurogenum, HHE-P21 as Penicillium cyclopium,HHE-A26 as Aspergillus versicolor and HHE-A8 as Aspergillus fumigatus, and it is hitherto unreported for biofloccutant-producing strains of Penicillium. The growth of the six strains(HHE6, HHE-P7, HHE-A8, HHE-P21, HHE-P24, HHE-A26) had similar curves, i.e. firstly increasing rapidly, keeping relatively constant then and finally decreasing gradually with cultivation time. The production of bioflocculants by strains showed the similar pattern to strain growth.

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

    NARCIS (Netherlands)

    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

  8. Gender Differences in Spouse Caregiver Strain: Socialization and Role Explanations.

    Science.gov (United States)

    Miller, Baila

    1990-01-01

    Examined gender differences in spouse caregiver strain among 554 spouse caregivers, using a multivariate model in which caregiver strains were a function of caregiver stressors and support resources. The effect of gender was found to be small; wives' greater experience of health strains appeared to result from situational factors and traditional…

  9. Nociception and Conditioned Fear in Rats: Strains Matter

    NARCIS (Netherlands)

    Schaap, M.W.H.; van Oostrom, H.; Doornenbal, A.; van 't Klooster, J.; Baars, A.M.; Arndt, S.S.; Hellebrekers, L.J.

    2013-01-01

    When using rats in pain research, strain-related differences in outcomes of tests for pain and nociception are acknowledged. However, very little is known about the specific characteristics of these strain differences. In this study four phylogenetically distant inbred rat strains, i.e. Wistar Kyoto

  10. Bordetella pertussis Strain Lacking Pertactin and Pertussis Toxin.

    Science.gov (United States)

    Williams, Margaret M; Sen, Kathryn; Weigand, Michael R; Skoff, Tami H; Cunningham, Victoria A; Halse, Tanya A; Tondella, M Lucia

    2016-02-01

    A Bordetella pertussis strain lacking 2 acellular vaccine immunogens, pertussis toxin and pertactin, was isolated from an unvaccinated infant in New York State in 2013. Comparison with a French strain that was pertussis toxin-deficient, pertactin wild-type showed that the strains carry the same 28-kb deletion in similar genomes.

  11. Fabrication and mechanical characterisation of inkjet printed strain gauges

    NARCIS (Netherlands)

    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

  12. Strain and strain rate: An emerging technology in the perioperative period.

    Science.gov (United States)

    Malik, Vishwas; Subramaniam, Arun; Kapoor, Poonam Malhotra

    2016-01-01

    Newer noninvasive parameters are being used for perioperative detection of myocardial ischaemia. TDI and global strain rate are some of these parameters. TDI signal is a modification of the routine Doppler flow signal. It is obtained by using thresholding and filtering algorithms that reject echoes originating from the blood pool (by-passing the high pass filter). Set-Up of the machine by activating the TDI function allows decreasing the system gain using a low pass filter and eliminates the signal produced by blood flow. Doppler shift obtained from myocardial tissue motion are of higher amplitudes (reflectivity 40 dB higher) and move about 10 times slower than blood (velocity range: 0.06 to 0.24 m/s). Speckle tracking echocardiography (tissue tracking, 2D strain) utilizes routine gray-scale 2D echo images to calculate myocardial strain. Interactions of ultrasound with myocardium result in reflection and scattering. These interactions generate a finely gray-shaded, speckled pattern (acoustic marker). This speckled pattern is unique for each myocardial region and relatively stable throughout the cardiac cycle. Spatial and temporal image processing of acoustic speckles in both 2D and 3D allows for the calculation of myocardial velocity, strain, and Strain rate.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Directory of Open Access Journals (Sweden)

    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.

  15. Radial and longitudinal strain and strain rate assessed by speckle-tracking echocardiography in dogs with myxomatous mitral valve disease

    DEFF Research Database (Denmark)

    Zois, Nora Elisabeth; Tidholm, A.; Nägga, K.M.;

    2012-01-01

    Assessment of left ventricular (LV) function using conventional echocardiographic methods is difficult in mitral regurgitation (MR) owing to altered hemodynamic loading conditions. Newer methods such as speckle-tracking echocardiography (STE) provide assessment of LV strain (St) and strain rates ...

  16. Early detection of left ventricular dysfunction in asymptomatic diabetic patient using strain and strain rate echocardiographic imaging

    Directory of Open Access Journals (Sweden)

    Rania Gaber

    2014-03-01

    Conclusion: Type 2 diabetes mellitus deteriorate both LV systolic and diastolic performance. Strain and strain rate by tissue Doppler Imaging is superior to conventional Doppler in early detection and evaluation of systolic and diastolic dysfunction in type 2 diabetic patients.

  17. Characterization of Phosphate Solubilizing and Potassium Decomposing Strains and Study on their Effects on Tomato Cultivation

    OpenAIRE

    Tin Mar Lynn; Hlaing Swe Win; Ei Phyu Kyaw; Zaw Ko Latt; San San Yu

    2013-01-01

    Seven strains were collected for phosphate solubilizing and potassium decomposing activities from Microbiology Laboratory, Department of Biotechnology, Shweziwa Biofertilizer Plant. When phosphate solubilizing activity of selected strains was qualitatively determined, all strains except from B1 strain, gave clear zone formation on NBRIP media. But when quantitatively determined by spectrophotometric method, all strains solubilized insoluble tricalcium phosphate. Among seven strains, Ps strain...

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

    Science.gov (United States)

    Gorski, Lisa

    2012-01-01

    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.

  19. Revealing Differences in Metabolic Flux Distributions between a Mutant Strain and Its Parent Strain Gluconacetobacter xylinus CGMCC 2955

    Science.gov (United States)

    Liu, Miao; Yang, Xiao-Ning; Zhu, Hui-Xia; Jia, Yuan-Yuan; Jia, Shi-Ru; Piergiovanni, Luciano

    2014-01-01

    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. PMID:24901455

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

    Directory of Open Access Journals (Sweden)

    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.

  1. Relationship between burgers vectors of dislocations and plastic strain localization patterns in compression-strained alkali halide crystals

    Science.gov (United States)

    Barannikova, S. A.; Nadezhkin, M. V.; Zuev, L. B.

    2011-08-01

    Plastic strain localization patterns in compression-strained alkali halide (NaCl, KCl, and LiF) crystals have been studied using a double-exposure speckle photography technique. The main parameters of strain localization autowaves at the linear stages of deformation hardening in alkali halide crystals have been determined. A quantitative relationship between the macroscopic parameters of plastic flow localization and microscopic parameters of strained alkali halide crystals has been established.

  2. Conversion of the BASE prion strain into the BSE strain: the origin of BSE?

    Science.gov (United States)

    Capobianco, Raffaella; Casalone, Cristina; Suardi, Silvia; Mangieri, Michela; Miccolo, Claudia; Limido, Lucia; Catania, Marcella; Rossi, Giacomina; Di Fede, Giuseppe; Giaccone, Giorgio; Bruzzone, Maria Grazia; Minati, Ludovico; Corona, Cristiano; Acutis, Pierluigi; Gelmetti, Daniela; Lombardi, Guerino; Groschup, Martin H; Buschmann, Anne; Zanusso, Gianluigi; Monaco, Salvatore; Caramelli, Maria; Tagliavini, Fabrizio

    2007-03-01

    Atypical neuropathological and molecular phenotypes of bovine spongiform encephalopathy (BSE) have recently been identified in different countries. One of these phenotypes, named bovine "amyloidotic" spongiform encephalopathy (BASE), differs from classical BSE for the occurrence of a distinct type of the disease-associated prion protein (PrP), termed PrP(Sc), and the presence of PrP amyloid plaques. Here, we show that the agents responsible for BSE and BASE possess different biological properties upon transmission to transgenic mice expressing bovine PrP and inbred lines of nontransgenic mice. Strikingly, serial passages of the BASE strain to nontransgenic mice induced a neuropathological and molecular disease phenotype indistinguishable from that of BSE-infected mice. The existence of more than one agent associated with prion disease in cattle and the ability of the BASE strain to convert into the BSE strain may have important implications with respect to the origin of BSE and spongiform encephalopathies in other species, including humans.

  3. High temperature static strain gage development

    Science.gov (United States)

    Hulse, C. O.; Bailey, R. S.; Grant, H. P.; Anderson, W. L.; Przybyszewski, J. S.

    1991-01-01

    Final results are presented from a program to develop a thin film static strain gage for use on the blades and vanes of running, test stand gas turbine engines with goals of an 3 x 3 mm gage area and total errors of less than 10 pct. of + or - 2,000 microstrain after 50 hrs at 1250 K. Pd containing 13 Wt. pct. Cr was previously identified as a new strain sensor alloy that appeared to be potentially usable to 1250 K. Subsequently, it was discovered, in contrast with its behavior in bulk, that Pd-13Cr suffered from oxidation attack when prepared as a 4.5 micron thick thin film. Continuing problems with electrical leakage to the substrate and the inability of sputtered alumina overcoats to prevent oxidation led to the discovery that sputtered alumina contains appreciable amounts of entrapped argon. After the argon has been exsolved by heating to elevated temperatures, the alumina films undergo a linear shrinkage of about 2 pct. resulting in formation of cracks. These problems can be largely overcome by sputtering the alumina with the substrate heated to 870 K. With 2 micron thick hot sputtered alumina insulation and overcoat films, total 50 hr drifts of about 100 microstrain (2 tests) and about 500 microstrain (1 test) were observed at 1000 and 1100 K, respectively. Results of tests on complete strain gage systems on constant moment bend bars with Pd temperature compensation grids revealed that oxidation of the Pd grid was a major problem even when the grid was overcoated with a hot or cold sputtered alumina overcoat.

  4. An atypical Clostridium strain related to the Clostridium botulinum group III strain isolated from a human blood culture.

    Science.gov (United States)

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

    Science.gov (United States)

    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,…

  6. Myocardial strain and strain rate in monitoring subclinical heart failure in asymptomatic long-term survivors of childhood cancer.

    NARCIS (Netherlands)

    Mavinkurve-Groothuis, A.M.C.; Groot-Loonen, J.J.; Marcus, K.A.; Bellersen, L.; Feuth, T.; Bokkerink, J.P.M.; Hoogerbrugge, P.M.; Korte, C.L. de; Kapusta, L.

    2010-01-01

    We studied the role of global myocardial strain and strain rate in monitoring subclinical heart failure in a large group of asymptomatic long-term survivors of childhood cancer. Global strain (rate) parameters of survivors were compared with those in healthy controls and were related to conventional

  7. The strain specificity of vaccination with ultra violet attenuated cercariae of the Chinese strain of Schistosoma japonicum.

    Science.gov (United States)

    Moloney, N A; Garcia, E G; Webbe, G

    1985-01-01

    Mice vaccinated with ultra violet (u.v.) attenuated cercariae of the Chinese mainland strain of S. japonicum were resistant to homologous challenge, but were not resistant to challenge with the Philippine strain of S. japonicum. Thus vaccination using u.v. attenuated S. japonicum cercariae is strain specific.

  8. The influence of acute unloading on left ventricular strain and strain rate by speckle tracking echocardiography in a porcine model.

    Science.gov (United States)

    Dahle, Geir Olav; Stangeland, Lodve; Moen, Christian Arvei; Salminen, Pirjo-Riitta; Haaverstad, Rune; Matre, Knut; Grong, Ketil

    2016-05-15

    Noninvasive measurements of myocardial strain and strain rate by speckle tracking echocardiography correlate to cardiac contractile state but also to load, which may weaken their value as indices of inotropy. In a porcine model, we investigated the influence of acute dynamic preload reductions on left ventricular strain and strain rate and their relation to the pressure-conductance catheter-derived preload recruitable stroke work (PRSW) and peak positive first derivative of left ventricular pressure (LV-dP/dtmax). Speckle tracking strain and strain rate in the longitudinal, circumferential, and radial directions were measured during acute dynamic reductions of end-diastolic volume during three different myocardial inotropic states. Both strain and strain rate were sensitive to unloading of the left ventricle (P speckle tracking echocardiography-derived strain rate is more robust to dynamic ventricular unloading than strain. Longitudinal and circumferential strain could not predict load-independent contractility. Strain rates, and especially in the radial direction, are good predictors of preload-independent inotropic markers derived from conductance catheter. Copyright © 2016 the American Physiological Society.

  9. Sequential acquisition of Potato virus Y strains by Myzus persicae favors the transmission of the emerging recombinant strains

    Science.gov (United States)

    In the past decade recombinant strains of potato virus Y (PVY) have overtaken the ordinary strain, PVYO, as the predominant viruses affecting the US seed potato crop. Aphids may be a contributing factor in the emergence of the recombinant strains, but studies indicate that differences in transmissio...

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

    Science.gov (United States)

    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.

  11. Repeated Strains, Social Control, Social Learning, and Delinquency: Testing an Integrated Model of General Strain Theory in China

    Science.gov (United States)

    Bao, Wan-Ning; Haas, Ain; Chen, Xiaojin; Pi, Yijun

    2014-01-01

    In Agnew's general strain theory, repeated strains can generate crime and delinquency by reducing social control and fostering social learning of crime. Using a sample of 615 middle-and high-school students in China, this study examines how social control and social learning variables mediate the effect of repeated strains in school and at home on…

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

    Directory of Open Access Journals (Sweden)

    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.

  13. May the use of different background strains 'strain' the stress-related phenotype of GR(+/-) mice?

    Science.gov (United States)

    Vogt, Miriam A; Pfeiffer, Natascha; Le Guisquet, Anne Marie; Brandwein, Christiane; Brizard, Bruno; Gass, Peter; Belzung, Catherine; Chourbaji, Sabine

    2017-09-29

    Genetically altered mice are available on different background strains. While respective backcrosses are often performed for pragmatic reasons, e.g. references, comparability, or existing protocols, the interaction between the mutations per se and the background strain often remains a neglected factor. The heterozygous mutation of the glucocorticoid receptor gene (GR) represents a well-examined model for depressive-like behavior in mice. To address the question in how far a robust depressive-like phenotype on a distinct background strain may allow a generalized conclusion, we analyzed respective phenotypes in two commonly used inbred strains: i.) C57BL/6N and ii.) BALB/c. Beside the use of different genetic models, we also extended our approach by applying two alternative paradigms to induce a depressive-like phenotype. Our study therefore comprised the model of 'unpredictable chronic mild stress' (UCMS) for four weeks and 'learned helplessness' (LH), which were used to study the role of GR, a key player in the development of depression. In the course of the experiment two cohorts of male GR(+/-) mice on either C57BL/6N or BALB/c background strain underwent a behavioral test battery to assess basal and depressive-like features. While both stress paradigms were functional in inducing depressive-like changes, the results were strictly strain-dependent. The genetic consequences became even more obvious under non-stress conditions with significant effects detected in BALB/c mice, which indicates a different basal stress predisposition due to differences in the genetic background. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. Strain localization along micro-boudinage

    Science.gov (United States)

    Chatziioannou, Eleftheria; Rogowitz, Anna; Grasemann, Bernhard; Habler, Gerlinde; Soukis, Konstantinos; Schneider, David

    2016-04-01

    The progressive development of boudinage strongly depends on the kinematic framework and the mechanical properties of the boudinaged layer and host rock. A common type of boudin, which can often be observed in natural examples, is the domino boudinage. This boudin type typically reflects a strong competency contrast of the interlayered rock sequences. Numerical models have shown that a relatively high amount of strain is necessary in order to develop separated boudin segments. With ongoing deformation and consequent rotation of the individual segments into the shear direction, the terminal sectors tend to experience a higher rotation rate, progressively resulting in isoclinal folding. Whereas most investigations of domino boudinage are cm- to dm-scale examples, we examined one order of magnitude smaller examples, where the deformation mechanism between the segments and the matrix could be directly investigated. The samples are from Kalymnos Island located in the southeastern Aegean Sea (Dodecanese islands-Greece). The analysed sample belongs to the upper unit of the pre-Alpidic basement, which consists of a succession of marbles, which were deformed under lower-greenschist facies conditions during the Variscan orogeny. 40Ar/39Ar geochronological dating on white micas in the adjacent upper quartz-mica schists unit yielded deformation ages between 240 and 334 Ma. The calcitic marble comprises boudinaged dolomite layers with thickness varying between 1 and 20 mm. Progressive deformation of the boudinaged layers resulted in the development of ptygmatic folds with fold axes parallel to the stretching lineation. The grain size from the host rock marbles (10 μm) decreases towards the boudinaged dolomite layer (5 μm) indicating strain localization adjacent to the dolomite layers. Furthermore, strain is localized within micro shear zones which nucleate in the necks of rotated boudin segments. Crystallographic preferred orientations (CPO) derived from electron backscatter

  15. Hydrogen production by recombinant Escherichia coli strains

    Science.gov (United States)

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

    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 increasing hydrogen production are outlined and whole‐cell systems and cell‐free systems are compared. PMID:21895995

  16. Quantum Chemical Strain Analysis For Mechanochemical Processes.

    Science.gov (United States)

    Stauch, Tim; Dreuw, Andreas

    2017-03-24

    The use of mechanical force to initiate a chemical reaction is an efficient alternative to the conventional sources of activation energy, i.e., heat, light, and electricity. Applications of mechanochemistry in academic and industrial laboratories are diverse, ranging from chemical syntheses in ball mills and ultrasound baths to direct activation of covalent bonds using an atomic force microscope. The vectorial nature of force is advantageous because specific covalent bonds can be preconditioned for rupture by selective stretching. However, the influence of mechanical force on single molecules is still not understood at a fundamental level, which limits the applicability of mechanochemistry. As a result, many chemists still resort to rules of thumb when it comes to conducting mechanochemical syntheses. In this Account, we show that comprehension of mechanochemistry at the molecular level can be tremendously advanced by quantum chemistry, in particular by using quantum chemical force analysis tools. One such tool is the JEDI (Judgement of Energy DIstribution) analysis, which provides a convenient approach to analyze the distribution of strain energy in a mechanically deformed molecule. Based on the harmonic approximation, the strain energy contribution is calculated for each bond length, bond angle and dihedral angle, thus providing a comprehensive picture of how force affects molecules. This Account examines the theoretical foundations of quantum chemical force analysis and provides a critical overview of the performance of the JEDI analysis in various mechanochemical applications. We explain in detail how this analysis tool is to be used to identify the "force-bearing scaffold" of a distorted molecule, which allows both the rationalization and the optimization of diverse mechanochemical processes. More precisely, we show that the inclusion of every bond, bending and torsion of a molecule allows a particularly insightful discussion of the distribution of mechanical

  17. Isolation of a Bacterium Strain Degraded Agar

    Institute of Scientific and Technical Information of China (English)

    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...

  18. Simultaneous measurement of temperature and strain using four connecting wires

    Science.gov (United States)

    Parker, Allen R., Jr.

    1993-01-01

    This paper describes a new signal-conditioning technique for measuring strain and temperature which uses fewer connecting wires than conventional techniques. Simultaneous measurement of temperature and strain has been achieved by using thermocouple wire to connect strain gages to signal conditioning. This signal conditioning uses a new method for demultiplexing sampled analog signals and the Anderson current loop circuit. Theory is presented along with data to confirm that strain gage resistance change is sensed without appreciable error because of thermoelectric effects. Furthermore, temperature is sensed without appreciable error because of voltage drops caused by strain gage excitation current flowing through the gage resistance.

  19. Strain analysis of nonlocal viscoelastic Kelvin bar in tension

    Institute of Scientific and Technical Information of China (English)

    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.

  20. Occurrence and diversity of mosquitocidal strains of Bacillus thuringiensis

    Directory of Open Access Journals (Sweden)

    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.

  1. Evidence for residual elastic strain in deformed natural quartz

    Energy Technology Data Exchange (ETDEWEB)

    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.

  2. A Novel Multidirectional, Non-Contact Strain-Sensing Nanocomposite

    Science.gov (United States)

    Withey, Paul; Vemuru, Srivishnu; Bachilo, Sergei; Nagarajaiah, Satish; Weisman, R. Bruce

    2013-03-01

    Single-walled carbon nanotubes (SWCNTs) have been successfully dispersed in a polymeric host resulting in the development of a novel strain-sensitive nanocomposite material with promise for scalability. Dubbed ``strain paint'' this new material when coated onto a surface becomes a smart-skin sensor that can detect strain through load transfer from the polymeric host to embedded SWCNTs. Strain is easily measured in a non-contact manner via laser excitation and detection of the unique near-infrared (NIR) fluorescence spectrum of semiconducting SWCNTs. When strained, each (n , m) SWCNT type exhibits a predictable shift in its NIR fluorescence peak. SWCNTs with high intensity are easily detected in the bulk fluorescence spectrum of raw, unsorted SWCNTs embedded in the polymer. Thin films of the polymer/SWCNT nanocomposite were spin-coated onto substrates, strains typically up to 1% were applied, and strain magnitudes were determined by resistive strain gauges bonded to the coating and substrate. Spectral shifts reveal a linear response to strain with little hysteresis. Two SWCNT types exhibiting opposite spectral shifts with strain were used to improve sensitivity. Strain along any direction is determined simply by adjusting the polarization of the excitation laser.

  3. Molecular Characterization of China Human Rabies Vaccine Strains

    Institute of Scientific and Technical Information of China (English)

    Xiaoyan Tao; Na Han; Zhenyang Guo; Qing Tang; Simon Rayner; Guodong Liang

    2013-01-01

    To understand the molecular characteristics of China human rabies vaccine strains,we report the full-length genome of the aG strain and present a comprehensive analysis of this strain and almost all available lyssavirus genomes (58 strains) from GenBank (as of Jan 6,2011).It is generally considered that the G protein plays a predominant role in determining the pathogenicity of the virus,to this end we predicted the tertiary structure of the G protein of aG strain,CTN 181 strain and wild type strain HN 10 based on the crystal structure of Vesicular stomatitis virus (VSV) G.The predicted RABV G structure has a similar topology to VSV G and the ectodomain can be divided into 4 distinct domains DI-DIV.By mapping the characterized mutations to this structure between China vaccine strains and their close street strains,we speculate that the G303(P-H) mutations of CTN181 and HN10 causing D Ⅱ 3D change may be associated with the attenuated virulence in both strains.Specifically,the two signature mutations (G165P and G231P) in the aG strain are withinβsheets,suggesting that both sites are of structural importance.

  4. Clinical strains of acinetobacter classified by DNA-DNA hybridization

    Energy Technology Data Exchange (ETDEWEB)

    Tjernberg, I.; Ursing, J. (Department of Medical Microbiology, University of Lund, Malmoe General Hospital, Malmoe (Sweden))

    1989-01-01

    A collection of Acinetobacter strains consisting of 168 consecutive clinical strains and 30 type and reference strains was studied by DNA-DNA hybridization and a few phenotypic tests. The field strains could be allotted to 13 DNA groups. By means of reference strains ten of these could be identified with groups described by Bouvet and Grimont (1986), while three groups were new; they were given the numbers 13-15. The type strain of A. radioresistens- recently described by Nishimura et al. (1988) - was shown to be a member of DNA group 12, which comprised 31 clinical isolates. Of the 19 strains of A. junii, eight showed hemolytic acitivity on sheep and human blood agar and an additional four strains on human blood agar only. Strains of this species have previously been regarded as non-hemolytic. Reciprocal DNA pairing data for the reference strains of the DNA gropus were treated by UPGMA clustering. The reference strains for A. calcoaceticus, A. baumannii and DNA groups 3 and 13 formed a cluster with about 70% relatedness within the cluster. Other DNA groups joined at levels below 60%. (author).

  5. Probiotic attributes of autochthonous Lactobacillus rhamnosus strains of human origin.

    Science.gov (United States)

    Pithva, Sheetal; Shekh, Satyamitra; Dave, Jayantilal; Vyas, Bharatkumar Rajiv Manuel

    2014-05-01

    The study was aimed at evaluating the probiotic potential of indigenous autochthonous Lactobacillus rhamnosus strains isolated from infant feces and vaginal mucosa of healthy female. The survival of the selected strains and the two reference strains (L. rhamnosus GG and L. casei Actimel) was 67-81 % at pH 2 and 70-80 % after passage through the simulated gastrointestinal fluid. These strains are able to grow in the presence of 4 % bile salt, 10 % NaCl, and 0.6 % phenol. The cell surface of L. rhamnosus strains is hydrophilic in nature as revealed by bacterial adhesion to hydrocarbons (BATH) assay. Despite this, L. rhamnosus strains showed mucin adherence, autoaggregation and coaggregation properties that are strain-specific. In addition, they produce bile salt hydrolase (BSH) and β-galactosidase activities. L. rhamnosus strains exhibit antimicrobial activity against food spoilage organisms and gastrointestinal pathogens, as well as Candida and Aspergillus spp. L. rhamnosus strains have similar antibiotic susceptibility pattern, and resistance to certain antibiotics is intrinsic or innate. The strains are neither haemolytic nor producer of biogenic amines such as histamine, putrescine, cadaverine and tyramine. Lyophilized cells of L. rhamnosus Fb exhibited probiotic properties demonstrating potential of the strain for technological suitability and in the preparation of diverse probiotic food formulations.

  6. Tasmancin and lysogenic bacteriophages induced from Erwinia tasmaniensis strains.

    Science.gov (United States)

    Müller, Ina; Lurz, Rudi; Geider, Klaus

    2012-07-25

    Mitomycin C treatment of Erwinia tasmaniensis strains from Australia induced prophages and the expression of bacteriocins. The bacteriocin named tasmancin inhibited E. tasmaniensis strains from South Africa and Germany. A gene cluster with a klebicin-related operon and an immunity protein was detected on plasmid pET46 from E. tasmaniensis strain Et1/99. PCR reactions using primers directed to this region produced signals for several strains originating from Australia, but not for strains isolated in South Africa and Germany. The latter isolates lacked plasmid pET46. Bacteriophages were induced from E. tasmaniensis strains Et88 and Et14/99, both isolates from South-Eastern Australia. These phages formed plaques on several other strains from this region, as well as on E. tasmaniensis strains from South Africa and Germany. Sequencing revealed similarity of phages ϕEt88 and ϕEt14, which shared the host range on E. tasmaniensis strains. Bacteriophages and tasmancin may interfere with the viability of several related E. tasmaniensis strains in the environment of carrier strains.

  7. Factors associated with strain in informal caregivers of stroke patients.

    Science.gov (United States)

    Hung, Jen-Wen; Huang, Yu-Ching; Chen, Jin-Hua; Liao, Li-Na; Lin, Chun-Ju; Chuo, Chia-Ying; Chang, Ku-Chou

    2012-01-01

    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. 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 ≥ 7 indicating considerable caregiver strain. Various factors associated with caregiver strain were analyzed using generalized estimating equations. 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 ≤ 60), poor cognition (Mini-Mental State Examination ≤ 23), depression (Beck Depression Inventory [BDI] ≥ 10), and recurrent stroke were predictors for caregiver strain. Caregiver factors, such as changed employment status, help from formal caregivers, and depression (BDI ≥ 10) were also associated with considerable caregiver strain. 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.

  8. Metabolic activities of Lactobacillus spp. strains isolated from kefir.

    Science.gov (United States)

    Yüksekdag, Zehra Nur; Beyath, Yavuz; Aslim, Belma

    2004-06-01

    A total of 21 strains of Lactobacillus species were isolated from Turkish kefir samples, in order to select the most suitable strains according to their metabolic activities including probiotic properties. As a result of the identification tests, 21 Lactobacillus isolates were identified as L. acidophilus (4%), L. helveticus (9%), L. brevis (9%), L. bulgaricus (14%), L. plantarum (14%), L. casei (19%) and L. lactis (28%). The amount of produced lactic acid, hydrogen peroxide, proteolytic activity, and acetaldehyde productions of Lactobacillus spp. were determined. Different amounts of lactic acid were produced by strains studies; however, lactic acid levels were 1.7-11.4 mg/mL. All strains produced hydrogen peroxide. L. bulgaricus Z14L strain showed no proteolytic activity, L. casei Z6L strain produced the maximum amount (0.16 mg/mL) of proteolytic activity. Acetaldehyde concentration produced in Lactobacillus strains ranged between 0.88-3.52 microg/mL.

  9. Evaluation of reproductive traits in three strains of japanese quail

    Directory of Open Access Journals (Sweden)

    A. Ashok

    2010-08-01

    Full Text Available A study was undertaken to evaluate the reproductive performance in two plumage colour variant strains of quail, viz; Brown, White Breasted and a dark Cinnamon Brown (commercial strain. A total of 694 straight run active chicks were obtained in three hatches at weekly intervals from the three strains. Sex was determined at six weeks of age and female progenies were separated and data on reproductive traits were recorded. The Brown strain exhibited superior egg weights (P<0.05 than the other two strains. The commercial strain came into egg production earlier and produced significantly (P<0.05 more number of eggs than the other two strains. [Vet World 2010; 3(4.000: 169-170

  10. Selection of strains for shiitake production in axenic substrate.

    Science.gov (United States)

    Zied, Diego Cunha; Maciel, William Pereira; Marques, Simone Cristina; da Silveira E Santos, Débora Marques; Rinker, Danny Lee; Dias, Eustáquio Souza

    2016-10-01

    Shiitake mushroom consumption is increasing in Brazil. In addition to the implementation of new production methods, it is also important to increase productivity, quality and reduce production costs. In this study, six commercial Lentinula edodes strains were characterized for genetic diversity (rep-PCR analysis) and mushroom production (yield, number and weight of individual mushrooms) using different substrates and cultural conditions. All strains showed genetic differences by repetitive element palindromic based-polymerase chain reaction (rep-PCR). The richest substrate resulted in the greatest production under both environmental conditions. Strains LE4 and LE6 produced the majority of their mushrooms earlier than the other strains. The highest number of mushrooms was observed in the LE6 strain while the highest weights of individual mushrooms were observed in the LE4 strain. Controlled environmental conditions resulted in superior production for all strains, except for LE4, which had empirically greater yield in the semi-controlled environmental condition.

  11. Graphene spin diode: Strain-modulated spin rectification

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yunhua; Wang, B., E-mail: stslyl@mail.sysu.edu.cn, E-mail: wangbiao@mail.sysu.edu.cn [Sino-French Institute of Nuclear Engineering and Technology, School of Physics and Engineering, State Key Laboratory of Optoelectronic Materials and Technologies, Sun Yat-sen University, Guangzhou 510275 (China); Liu, Yulan, E-mail: stslyl@mail.sysu.edu.cn, E-mail: wangbiao@mail.sysu.edu.cn [School of Engineering, Sun Yat-sen University, Guangzhou 510275 (China)

    2014-08-04

    Strain effects on spin transport in a ferromagnetic/strained/normal graphene junction are explored theoretically. It is shown that the spin-resolved Fermi energy range can be controlled by the armchair direction strain because the strain-induced pseudomagnetic field suppresses the current. The spin rectification effect for the bias reversal occurs because of a combination of ferromagnetic exchange splitting and the broken spatial symmetry of the junction. In addition, the spin rectification performance can be tuned remarkably by manipulation of the strains. In view of this strain-modulated spin rectification effect, we propose that the graphene-based ferromagnetic/strained/normal junction can be used as a tunable spin diode.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    CERN Document Server

    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...

  14. Strain partitioning in dual-phase steels containing tempered martensite

    Energy Technology Data Exchange (ETDEWEB)

    Han, Qihang, E-mail: hanqihang@baosteel.com [Research Institute, Baoshan Iron and Steel Co., Ltd., Shanghai 201900 (China); State Key Laboratory of Development and Application Technology of Automotive Steels (BaoSteel), Shanghai 201900 (China); Institute for Frontier Materials, Deakin University, Geelong, VIC. 3217 (Australia); Asgari, Alireza; Hodgson, Peter D.; Stanford, Nicole [State Key Laboratory of Development and Application Technology of Automotive Steels (BaoSteel), Shanghai 201900 (China)

    2014-08-12

    Tempering has been used as a method to develop a range of dual phase steels with the same martensite morphology and volume fraction, but containing phases with different relative strengths. These steels were used to examine the strain partitioning between the two constituent phases experimentally through mechanical testing and numerically through finite element modelling. It was found that increasing the differential in strength between the two phases not only produces regions of high strain, but also regions of low strain. On average, a larger difference in strength between the phases increased the strain carried by the softer phase. There was no discernible preferential strain localisation to the ferrite/martensite interface, with the regions of strain localisation being determined by the morphology of the microstructure. A direct correlation between the average strain in the ferrite, and the measured ductility has been found.

  15. Strain compatibility assessment for SRB sprayable ablator MSA-1

    Science.gov (United States)

    Patterson, W. J.

    1979-01-01

    Tensile and compressive strain compatibility testing was performed on as-sprayed samples of the Shuttle Solid Rocket Booster external ablator material, MSA-1. Strain gages on the aluminum substrate were used to monitor strain. Strain compatibility was determined as the percent strain in the substrate at first visual evidence of MSA-1 failure. The 1/8-in. MSA-1, baselined for large areas of the SRB external skin, was characterized by a strain compatibility of 1.5 to 1.8 percent, which far exceeded the yield range of the metal substrate. Thicker MSA-1 applications (1.4 to 3/8 in.) were characterized by a lower level of strain compatibility, which appeared to be a manifestation of application limitations.

  16. Mechanical control over valley magnetotransport in strained graphene

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Ning, E-mail: maning@stu.xjtu.edu.cn [Department of Physics, MOE Key Laboratory of Advanced Transducers and Intelligent Control System, Taiyuan University of Technology, Taiyuan 030024 (China); Department of Applied Physics, MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, Xi' an Jiaotong University, Xi' an 710049 (China); Zhang, Shengli, E-mail: zhangsl@mail.xjtu.edu.cn [Department of Applied Physics, MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, Xi' an Jiaotong University, Xi' an 710049 (China); Liu, Daqing, E-mail: liudq@cczu.edu.cn [School of Mathematics and Physics, Changzhou University, Changzhou 213164 (China)

    2016-05-06

    Recent experiments report that the graphene exhibits Landau levels (LLs) that form in the presence of a uniform strain pseudomagnetic field with magnitudes up to hundreds of tesla. We further reveal that the strain removes the valley degeneracy in LLs, and leads to a significant valley polarization with inversion symmetry broken. This accordingly gives rise to the well separated valley Hall plateaus and Shubnikov–de Haas oscillations. These effects are absent in strainless graphene, and can be used to generate and detect valley polarization by mechanical means, forming the basis for the new paradigm “valleytronics” applications. - Highlights: • We explore the mechanical strain effects on the valley magnetotransport in graphene. • We analytically derive the dc collisional and Hall conductivities under strain. • The strain removes the valley degeneracy in Landau levels. • The strain causes a significant valley polarization with inversion symmetry broken. • The strain leads to the well separated valley Hall and Shubnikov–de Haas effects.

  17. Best Harvest Time Study of Rabdosia rubescens Hara%冬凌草适宜采收期的研究

    Institute of Scientific and Technical Information of China (English)

    李洋; 董诚明; 徐鹏; 姚锋

    2014-01-01

    目的:通过研究冬凌草生长时期的发育规律及有效成分的变化,初步探讨冬凌草的适宜采收时期.方法:在冬凌草整个生长发育过程中,对株高、鲜干重的变化进行测量,并用HPLC法测定植株中冬凌草甲素、冬凌草乙素、迷迭香酸的含量,进行分析.结果:冬凌草干物质累积的高峰期出现在9月下旬;冬凌草甲素含量在9月下旬出现相对较大值;冬凌草乙素在6月下旬出现最大值,在9月下旬出现相对较大值;迷迭香酸在6月下旬出现最大值,8月下旬出现相对较大值.结论:综合分析,栽植期为一年的冬凌草适宜采收期为9月下旬.

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

    Directory of Open Access Journals (Sweden)

    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.

  19. Substrate-induced strain in carbon nanodisks

    Energy Technology Data Exchange (ETDEWEB)

    Osváth, Z., E-mail: osvath.zoltan@ttk.mta.hu [Institute of Technical Physics and Materials Science, MFA, Research Centre for Natural Sciences, 1525 Budapest, P.O. Box 49 (Hungary); Korea–Hungary Joint Laboratory for Nanosciences (KHJLN), P.O. Box 49, 1525 Budapest (Hungary); Vértesy, Z. [Institute of Technical Physics and Materials Science, MFA, Research Centre for Natural Sciences, 1525 Budapest, P.O. Box 49 (Hungary); Korea–Hungary Joint Laboratory for Nanosciences (KHJLN), P.O. Box 49, 1525 Budapest (Hungary); Lábár, J. [Institute of Technical Physics and Materials Science, MFA, Research Centre for Natural Sciences, 1525 Budapest, P.O. Box 49 (Hungary); Nemes-Incze, P.; Horváth, Z.E.; Biró, L.P. [Institute of Technical Physics and Materials Science, MFA, Research Centre for Natural Sciences, 1525 Budapest, P.O. Box 49 (Hungary); Korea–Hungary Joint Laboratory for Nanosciences (KHJLN), P.O. Box 49, 1525 Budapest (Hungary)

    2014-08-28

    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.

  20. Aseismic strain episodes at Campi Flegrei, Italy

    Science.gov (United States)

    Scarpa, Roberto; Amoruso, Antonella; Bilham, Roger; Di Lieto, Bellina; Errico, Antonio; Linde, Alan; Sacks, Selwyn

    2014-05-01

    Since spring 2004 a research project has been developed in Italy to install borehole Sacks-Evertson strainmeters (dilatometers) aimed to improve monitoring systems of the Italian volcanoes. 6 borehole dilatometers have been installed around Campi Flegrei and Vesuvius during 2004-2005 (Scarpa et al., 2007). This small network has been implemented by two arrays of long-baseline water tube tiltmeters installed in underground tunnels since 2008. Relevant strainmeter and tiltmeter data have been collected and analyzed at the instruments installed at Campi Flegrei during the recent unrest episodes. Renewed activity started since 2004-2005, characterized by a quite low rate of vertical vertical displacement, amounting initially to a few cm/year. A long term strain episode occurred during summer 2006, in correspondence to an increase of CO2 emission and displacements measured also by tiltmeters and GPS transducers. This strain episode preceded the seismic activity by few months, as also observed during the 1982 most significant unrest. Other aseismic slip episodes have been recorded in 2009, in correspondence of the renewal of gas emission activity at Solfatara, in 2010, one day before a seismic swarm, and in September 2012, few days before the most significant seismic swarm occurred after the 1982-1984 uplift. The time scale of these phenomena is ranging from some hours to several days, putting further constraints on the origin of ground uplifts at Campi Flegrei. Their location is compatible with the source inferred from long term deformation signals, at about 4 km depth beneath Pozzuoli.

  1. Valsalva maneuver: shortest optimal expiratory strain duration

    Directory of Open Access Journals (Sweden)

    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.

  2. Physics of strained quantum well lasers

    CERN Document Server

    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...

  3. Major flood related strains and pregnancy outcomes.

    Science.gov (United States)

    Hilmert, Clayton J; Kvasnicka-Gates, Lexi; Teoh, Ai Ni; Bresin, Konrad; Fiebiger, Siri

    2016-11-01

    To assess the impact of experiencing a major flood during pregnancy on fetal growth and length of gestation, and to consider how flood-related strains might contribute to these effects. The Red River Pregnancy Project was a prospective study carried out for 3 months immediately after the historic 2009 crest of the Red River in Fargo, North Dakota. Pregnant community residents who were at least 18 years old with a singleton, intrauterine pregnancy participated in the study (N = 169). Analyses examined if birth weight and length of gestation were associated with residential distance from flooding and gestational age at time of the flood crest. For pregnancies earlier in gestation during the crest (-1 SD = 12 weeks), birth weight decreased as distance from flooding decreased (-42.29 g/mi, p .10). Biparietal growth trajectories showed a decrease in growth after the crest of the flood but only for women early in pregnancy. However, various measures of flood related and general stress or strain did not explain these effects. Length of gestation was not associated with distance from or the timing of the flood. Pregnant women in the first trimester who experience a major flood near their homes are at risk of having lower birth weight neonates due to a reduction in fetal growth. The mechanisms of this effect deserve further attention in rapidly mounted investigations after disaster. (PsycINFO Database Record (c) 2016 APA, all rights reserved).

  4. Strain engineered pyrochlore at high pressure

    Energy Technology Data Exchange (ETDEWEB)

    Rittman, Dylan R.; Turner, Katlyn M.; Park, Sulgiye; Fuentes, Antonio F.; Park, Changyong; Ewing, Rodney C.; Mao, Wendy L.

    2017-05-22

    Strain engineering is a promising method for next-generation materials processing techniques. Here, we use mechanical milling and annealing followed by compression in diamond anvil cell to tailor the intrinsic and extrinsic strain in pyrochlore, Dy2Ti2O7 and Dy2Zr2O7. Raman spectroscopy, X-ray pair distribution function analysis, and X-ray diffraction were used to characterize atomic order over short-, medium-, and long-range spatial scales, respectively, under ambient conditions. Raman spectroscopy and X-ray diffraction were further employed to interrogate the material in situ at high pressure. High-pressure behavior is found to depend on the species and concentration of defects in the sample at ambient conditions. Overall, we show that defects can be engineered to lower the phase transformation onset pressure by ~50% in the ordered pyrochlore Dy2Zr2O7, and lower the phase transformation completion pressure by ~20% in the disordered pyrochlore Dy2Zr2O7. These improvements are achieved without significantly sacrificing mechanical integrity, as characterized by bulk modulus.

  5. Fermentation characteristics of Dekkera bruxellensis strains.

    Science.gov (United States)

    Blomqvist, Johanna; Eberhard, Thomas; Schnürer, Johan; Passoth, Volkmar

    2010-07-01

    The influence of pH, temperature and carbon source (glucose and maltose) on growth rate and ethanol yield of Dekkera bruxellensis was investigated using a full-factorial design. Growth rate and ethanol yield were lower on maltose than on glucose. In controlled oxygen-limited batch cultivations, the ethanol yield of the different combinations varied from 0.42 to 0.45 g (g glucose)(-1) and growth rates varied from 0.037 to 0.050 h(-1). The effect of temperature on growth rate and ethanol yield was negligible. It was not possible to model neither growth rate nor ethanol yield from the full-factorial design, as only marginal differences were observed in the conditions tested. When comparing three D. bruxellensis strains and two industrial isolates of Saccharomyces cerevisiae, S. cerevisiae grew five times faster, but the ethanol yields were 0-13% lower. The glycerol yields of S. cerevisiae strains were up to six-fold higher compared to D. bruxellensis, and the biomass yields reached only 72-84% of D. bruxellensis. Our results demonstrate that D. bruxellensis is robust to large changes in pH and temperature and may have a more energy-efficient metabolism under oxygen limitation than S. cerevisiae.

  6. Investigation of the interface characteristics of Y2O3/GaAs under biaxial strain, triaxial strain, and non-strain conditions

    Science.gov (United States)

    Shi, Li-Bin; Liu, Xu-Yang; Dong, Hai-Kuan

    2016-09-01

    We investigate the interface behaviors of Y2O3/GaAs under biaxial strain, triaxial strain, and non-strain conditions. This study is performed by first principles calculations based on density functional theory (DFT). First of all, the biaxial strain is realized by changing the lattice constants in ab plane. Averaged electrostatic potential (AEP) is aligned by establishing Y2O3 and GaAs (110) surfaces. The band offsets of Y2O3/GaAs interface under biaxial strain are investigated by generalized gradient approximation and Heyd-Scuseria-Ernzerhof (HSE) functionals. The interface under biaxial strain is suitable for the design of metal oxide semiconductor (MOS) devices because the valence band offsets (VBO) and conduction band offsets (CBO) are larger than 1 eV. Second, the triaxial strain is applied to Y2O3/GaAs interface by synchronously changing the lattice constants in a, b, and c axis. The band gaps of Y2O3 and GaAs under triaxial strain are investigated by HSE functional. We compare the VBO and CBO under triaxial strain with those under biaxial strain. Third, in the absence of lattice strain, the formation energies, charge state switching levels, and migration barriers of native defects in Y2O3 are assessed. We investigate how they will affect the MOS device performance. It is found that VO+2 and Oi-2 play a very dangerous role in MOS devices. Finally, a direct tunneling leakage current model is established. The model is used to analyze current and voltage characteristics of the metal/Y2O3/GaAs.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    Carrion, Patricio E.; Shamsaei, Nima

    2016-01-01

    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

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

    Directory of Open Access Journals (Sweden)

    Patricio E. Carrion

    2016-06-01

    Full Text Available 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.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    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

  12. Total strain version of strainrange partitioning for thermomechanical fatigue at low strains

    Science.gov (United States)

    Halford, G. R.; Saltsman, J. F.

    1987-01-01

    A new method is proposed for characterizing and predicting the thermal fatigue behavior of materials. The method is based on three innovations in characterizing high temperature material behavior: (1) the bithermal concept of fatigue testing; (2) advanced, nonlinear, cyclic constitutive models; and (3) the total strain version of traditional strainrange partitioning.

  13. Measurement of strain and strain rate in embryonic chick heart using spectral domain optical coherence tomography

    Science.gov (United States)

    Dou, Shidan; Suo, Yanyan; Liang, Chengbo; Wang, Yi; Zhao, Yuqian; Liu, Jian; Xu, Tao; Wang, Ruikang; Ma, Zhenhe

    2016-03-01

    It is important to measure embryonic heart myocardial wall strain and strain rate for understanding the mechanisms of embryonic heart development. Optical coherence tomography (OCT) can provide depth resolved images with high spatial and temporal resolution, which makes it have the potential to reveal the complex myocardial activity in the early stage embryonic heart. We develop a novel method to measure strain in embryonic chick heart based on spectral domain OCT images and subsequent image processing. We perform 4D(x,y,z,t) scanning on the outflow tract (OFT) of chick embryonic hearts in HH18 stage (~3 days of incubation). Only one image sequence acquired at the special position is selected based on the Doppler blood flow information where the probe beam penetrates through the OFT perpendicularly. For each image of the selected sequence, the cross-section of the myocardial wall can be approximated as an annulus. The OFT is segmented with a semi-automatic boundary detection algorithm, thus the area and mean circumference of the annular myocardial wall can be achieved. The myocardial wall thickness was calculated using the area divided by the mean circumference, and then the strain was obtained. The results demonstrate that OCT can be a useful tool to describe the biomechanical characteristics of the embryonic heart.

  14. Direct measurement of intrinsic critical strain and internal strain in barrier films

    NARCIS (Netherlands)

    Vellinga, W. P.; De Hosson, J. Th M.; Bouten, P. C. P.

    2011-01-01

    Resistance measurements during uniaxial tensile deformation of very thin (10 nm) conducting oxide films deposited on 150 nm SiN films on polyethylene naphthalate are discussed. It is first shown that certain characteristics of resistance versus strain curves are representative for the fracture behav

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

    Science.gov (United States)

    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.

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

    DEFF Research Database (Denmark)

    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...

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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; Reunanen, Justus; Palva, Airi; de Vos, Willem M

    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. These strains were phenotypically characterized for a wide range of metabolic, antagonistic, signalling and functional properties. Phylogenomic analysis showed multiple groupings of the species that could partly be associated with their ecological niches. We identified 17 highly variable regions that encode functions related to lifestyle, i.e. carbohydrate transport and metabolism, production of mucus-binding pili, bile salt resistance, prophages and CRISPR adaptive immunity. Integration of the phenotypic and genomic data revealed that some L. rhamnosus strains possibly resided in multiple niches, illustrating the dynamics of bacterial habitats. The present study showed two distinctive geno-phenotypes in the L. rhamnosus species. The geno-phenotype A suggests an adaptation to stable nutrient-rich niches, i.e. milk-derivative products, reflected by the alteration or loss of biological functions associated with antimicrobial activity spectrum, stress resistance, adaptability and fitness to a distinctive range of habitats. In contrast, the geno-phenotype B displays adequate traits to a variable environment, such as the intestinal tract, in terms of nutrient resources, bacterial population density and host effects.

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

    Directory of Open Access Journals (Sweden)

    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.

  1. Finite Element Modeling of the Behavior of Armor Materials Under High Strain Rates and Large Strains

    Science.gov (United States)

    Polyzois, Ioannis

    For years high strength steels and alloys have been widely used by the military for making armor plates. Advances in technology have led to the development of materials with improved resistance to penetration and deformation. Until recently, the behavior of these materials under high strain rates and large strains has been primarily based on laboratory testing using the Split Hopkinson Pressure Bar apparatus. With the advent of sophisticated computer programs, computer modeling and finite element simulations are being developed to predict the deformation behavior of these metals for a variety of conditions similar to those experienced during combat. In the present investigation, a modified direct impact Split Hopkinson Pressure Bar apparatus was modeled using the finite element software ABAQUS 6.8 for the purpose of simulating high strain rate compression of specimens of three armor materials: maraging steel 300, high hardness armor (HHA), and aluminum alloy 5083. These armor materials, provided by the Canadian Department of National Defence, were tested at the University of Manitoba by others. In this study, the empirical Johnson-Cook visco-plastic and damage models were used to simulate the deformation behavior obtained experimentally. A series of stress-time plots at various projectile impact momenta were produced and verified by comparison with experimental data. The impact momentum parameter was chosen rather than projectile velocity to normalize the initial conditions for each simulation. Phenomena such as the formation of adiabatic shear bands caused by deformation at high strains and strain rates were investigated through simulations. It was found that the Johnson-Cook model can accurately simulate the behavior of body-centered cubic (BCC) metals such as steels. The maximum shear stress was calculated for each simulation at various impact momenta. The finite element model showed that shear failure first occurred in the center of the cylindrical specimen and

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  3. The complete genome of Enterovirus 71 China strain

    Institute of Scientific and Technical Information of China (English)

    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.

  4. Step width alters iliotibial band strain during running.

    Science.gov (United States)

    Meardon, Stacey A; Campbell, Samuel; Derrick, Timothy R

    2012-11-01

    This study assessed the effect of step width during running on factors related to iliotibial band (ITB) syndrome. Three-dimensional (3D) kinematics and kinetics were recorded from 15 healthy recreational runners during overground running under various step width conditions (preferred and at least +/- 5% of their leg length). Strain and strain rate were estimated from a musculoskeletal model of the lower extremity. Greater ITB strain and strain rate were found in the narrower step width condition (p < 0.001, p = 0.040). ITB strain was significantly (p < 0.001) greater in the narrow condition than the preferred and wide conditions and it was greater in the preferred condition than the wide condition. ITB strain rate was significantly greater in the narrow condition than the wide condition (p = 0.020). Polynomial contrasts revealed a linear increase in both ITB strain and strain rate with decreasing step width. We conclude that relatively small decreases in step width can substantially increase ITB strain as well as strain rates. Increasing step width during running, especially in persons whose running style is characterized by a narrow step width, may be beneficial in the treatment and prevention of running-related ITB syndrome.

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

    Directory of Open Access Journals (Sweden)

    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.

  6. Antimicrobial drug susceptibility of Neisseria meningitidis strains isolated from carriers

    Directory of Open Access Journals (Sweden)

    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.

  7. Strain diversity and phage resistance in complex dairy starter cultures.

    Science.gov (United States)

    Spus, M; Li, M; Alexeeva, S; Wolkers-Rooijackers, J C M; Zwietering, M H; Abee, T; Smid, E J

    2015-08-01

    The compositional stability of the complex Gouda cheese starter culture Ur is thought to be influenced by diversity in phage resistance of highly related strains that co-exist together with bacteriophages. To analyze the role of bacteriophages in maintaining culture diversity at the level of genetic lineages, simple blends of Lactococcus lactis strains were made and subsequently propagated for 152 generations in the absence and presence of selected bacteriophages. We first screened 102 single-colony isolates (strains) from the complex cheese starter for resistance to bacteriophages isolated from this starter. The collection of isolates represents all lactococcal genetic lineages present in the culture. Large differences were found in bacteriophage resistance among strains belonging to the same genetic lineage and among strains from different lineages. The blends of strains were designed such that 3 genetic lineages were represented by strains with different levels of phage resistance. The relative abundance of the lineages in blends with phages was not stable throughout propagation, leading to continuous changes in composition up to 152 generations. The individual resistance of strains to phage predation was confirmed as one of the factors influencing starter culture diversity. Furthermore, loss of proteolytic activity of initially proteolytic strains was found. Reconstituted blends with only 4 strains with a variable degree of phage resistance showed complex behavior during prolonged propagation. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  8. High strain rate loading of polymeric foams and solid plastics

    Science.gov (United States)

    Dick, Richard D.; Chang, Peter C.; Fourney, William L.

    2000-04-01

    The split-Hopkinson pressure bar (SHPB) provided a technique to determine the high strain rate response for low density foams and solid ABS and polypropylene plastics. These materials are used in the interior safety panels of automobiles and crash test dummies. Because the foams have a very low impedance, polycarbonate bars were used to acquire the strain rate data in the 100 to 1600 l/s range. An aluminum SPHB setup was used to obtain the solid plastics data which covered strain rates of 1000 to 4000 l/s. The curves for peak strain rate versus peak stress for the foams over the test range studied indicates only a slight strain rate dependence. Peak strain rate versus peak stress curves for polypropylene shows a strain rate dependence up to about 1500 l/s. At that rate the solid poly propylene indicates no strain rate dependence. The ABS plastics are strain rate dependent up to 3500 l/s and then are independent at larger strain rates.

  9. Molecular characterization of Bacillus thuringiensis strains from Argentina.

    Science.gov (United States)

    Franco-Rivera, Alejandro; Benintende, Graciela; Cozzi, Jorge; Baizabal-Aguirre, Victor Manuel; Valdez-Alarcón, Juan José; López-Meza, Joel Edmundo

    2004-07-01

    Bacillus thuringiensis INTA 7-3, INTA 51-3, INTA Mo9-5 and INTA Mo14-4 strains were obtained from Argentina and characterized by determination of serotype, toxicity, plasmid composition, insecticidal gene content ( cry and vip ) and the cloning of the single- vip3A gene of the INTA Mo9-5 strain. The serotype analysis identified the serovars tohokuensis and darmstadiensis for the INTA 51-3 and INTA Mo14-4 strains, respectively, whereas the INTA Mo9-5 strain was classified as "autoagglutinated". In contrast to the plasmid patterns of INTA 7-3, INTA 51-3 and INTA Mo9-5 (which were similar to B. thuringiensis HD-1 strain), strain INTA Mo14-4 showed a unique plasmid array. PCR analysis of the four strains revealed the presence of cry genes and vip3A genes. Interestingly, it was found that B. thuringiensis 4Q7 strain, which is a plasmid cured strain, contained vip3A genes indicating the presence of these insecticidal genes in the chromosome. Bioassays towards various lepidopteran species revealed that B. thuringiensis INTA Mo9-5 and INTA 7-3 strains were highly active. In particular, the mean LC(50) obtained against A. gemmatalis larvae with the INTA Mo9-5 and INTA 7-3 strains were 7 (5.7-8.6) and 6.7 (5.6-8.0) ppm, respectively. The INTA Mo14-4 strain was non-toxic and strain INTA 51-3 showed only a weak larvicidal activity.

  10. Feed consumption of egg strain pullets at onset of lay.

    Science.gov (United States)

    Bai, Y S; Sunde, M L

    1991-04-01

    An experiment was conducted to investigate the performance of four strains of commercial egg type pullets (A, B, C, and D) from 19 to 30 wk of age. The feed consumption differences during this period as well as feed consumption patterns 10 days prior to and after the first oviposition were of special interest. Two hundred and sixty-four birds (66 birds per strain) were fed a diet formulated to contain 2,750 kcal/kg ME, 17% CP, and 3.4% calcium. Results show that the average age to the first egg and percentage of hen-day egg production were not significantly different among the four strains of birds. However, egg weights of Strain A and C birds were significantly heavier than those of the Strain B and D birds. The birds from Strains B and D had significantly lower body weight than Strain A birds at the end of 18 wk, but body weights were not significantly different at the end of 30 wk. Feed intake per bird per day of pullets from Strains A and C was generally higher than that of those from Strains B and D in the first and second 4-wk period. Some of the consumption differences were significant. Feed intake in the third period (27 to 30 wk) was similar for the four strains of birds. Although different strains showed different feed consumption patterns around the first oviposition, all strains showed a drop on the day of the first oviposition. When the strains were combined, feed consumption was lower on that day than during the 8 days prior to the first oviposition.

  11. Serological characterization of Actinobacillus pleuropneumoniae biotype 1 strains antigenically related to both serotypes 2 and 7

    DEFF Research Database (Denmark)

    Nielsen, R.; Andresen, Lars Ole; Plambeck, Tamara

    1996-01-01

    Nine Danish Actinobacillus pleuropneumoniae biotype 1 isolates were shown by latex agglutination and indirect haemagglutination to possess capsular polysaccharide epitopes identical to those of serotype 2 strain 1536 (reference strain of serotype 2) and strain 4226 (Danish serotype 2 strain...

  12. Global Strain in Severe Aortic Valve Stenosis

    DEFF Research Database (Denmark)

    Dahl, Jordi S; Videbæk, Lars; Poulsen, Mikael K

    2012-01-01

    BACKGROUND: -Global longitudinal systolic strain (GLS) is often reduced in aortic stenosis despite normal ejection fraction. The importance of reduced preoperative GLS on long-term outcome after aortic valve replacement (AVR) is unknown. METHODS AND RESULTS: -A total of 125 patients with severe...... aortic stenosis and ejection fraction >40% scheduled for AVR were evaluated preoperatively and divided into 4 groups according to GLS quartiles. Patients were followed up for 4 years. The primary endpoint was major adverse cardiac events (MACE) defined as cardiovascular mortality and cardiac......Score, history with ischemic heart disease and ejection fraction. CONCLUSIONS: -In patients with symptomatic severe aortic stenosis undergoing AVR reduced GLS provides important prognostic information beyond standard risk factors. Clinical Trial Registration-URL: http://www.clinicaltrial.gov. Unique identifier...

  13. Landau Levels in Strained Optical Lattices.

    Science.gov (United States)

    Tian, Binbin; Endres, Manuel; Pekker, David

    2015-12-01

    We propose a hexagonal optical lattice system with spatial variations in the hopping matrix elements. Just like in the valley Hall effect in strained graphene, for atoms near the Dirac points the variations in the hopping matrix elements can be described by a pseudomagnetic field and result in the formation of Landau levels. We show that the pseudomagnetic field leads to measurable experimental signatures in momentum resolved Bragg spectroscopy, Bloch oscillations, cyclotron motion, and quantization of in situ densities. Our proposal can be realized by a slight modification of existing experiments. In contrast to previous methods, pseudomagnetic fields are realized in a completely static system avoiding common heating effects and therefore opening the door to studying interaction effects in Landau levels with cold atoms.

  14. LASER SPECTRAL ANALYSIS OF STRAIN MEASUREM ENT

    Institute of Scientific and Technical Information of China (English)

    姜耀东; 陈至达

    1994-01-01

    Modern optical theory has shown that the far field or Fraunhofer diffraction equipment is identical to the Fourier spectral analyzer. In the Fourier spectral analyzer the Fourier spectra or the Fraunhofer diffraction pattern of a graph is formed on the back foeal plane when a laser beam is directed on the graph lying on the front focal plane; the Fourier spectra of the graph is also subjected to change during the deformation of the graph. Through analyzing the change of Fourier spectra the deformation of the graph can be obtained. A few years ago, based on the above principles the authors proposed a new technique of strain measurement by laser spectral analysis. Demonstration and discussion will be made in detail in this paper.

  15. Engineering clostridium strain to accept unmethylated DNA.

    Directory of Open Access Journals (Sweden)

    Hongjun Dong

    Full Text Available It is difficult to genetically manipulate the medically and biotechnologically important genus Clostridium due to the existence of the restriction and modification (RM systems. We identified and engineered the RM system of a model clostridial species, C. acetobutylicum, with the aim to allow the host to accept the unmethylated DNA efficiently. A gene CAC1502 putatively encoding the type II restriction endonuclease Cac824I was identified from the genome of C. acetobutylicum DSM1731, and disrupted using the ClosTron system based on group II intron insertion. The resulting strain SMB009 lost the type II restriction endonuclease activity, and can be transformed with unmethylated DNA as efficiently as with methylated DNA. The strategy reported here makes it easy to genetically modify the clostridial species using unmethylated DNA, which will help to advance the understanding of the clostridial physiology from the molecular level.

  16. Social relations: network, support and relational strain

    DEFF Research Database (Denmark)

    Due, P; Holstein, B; Lund, Rikke

    1999-01-01

    ,011. The 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......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......, social anchorage and relational strain. We use this conceptual framework to describe social relations in the Danish population, with questionnaire data from the Danish Longitudinal Health Behaviour Study including a random sample of each of the age groups 25-, 50-, 60-and 70-year olds, N = 2...

  17. Cryopreservation of basidiomycete strains using perlite.

    Science.gov (United States)

    Homolka, L; Lisá, L; Eichlerová, I; Nerud, F

    2001-12-01

    A new alternative method using perlite as a particulate solid carrier in the growth medium with a cryoprotectant was successfully tested for cryopreservation of several basidiomycete species from different genera (Armillaria, Pleurotus, Pluteus, Polyporus) which failed to survive or retain their properties in cryopreservation procedures routinely used in our laboratory. Frozen basidiomycete strains were kept in cryovials submerged in liquid nitrogen and were either immediately after the freezing process or after a 6-month storage thawed and checked for viability, purity and changes in growth, morphology and biochemical characteristics. All cultures survived the cryopreservation procedure and no negative effects of cryopreservation by this method have been observed after 6 months of storage in liquid nitrogen.

  18. Easy storage strategies for Sporothrix spp. strains.

    Science.gov (United States)

    Brilhante, Raimunda Sâmia Nogueira; Silva, Natalya Fechine; Lima, Rita Amanda Chaves de; Caetano, Érica Pacheco; Alencar, Lucas Pereira de; Castelo-Branco, Débora de Souza Collares Maia; Moreira, José Luciano Bezerra; Bandeira, Silviane Praciano; Camargo, Zoilo Pires de; Rodrigues, Anderson Messias; Bandeira, Tereza de Jesus Pinheiro Gomes; Monteiro, André Jalles; Cordeiro, Rossana de Aguiar; Sidrim, José Júlio Costa; Rocha, Marcos Fábio Gadelha

    2015-04-01

    The present study evaluated the maintenance of Sporothrix spp. (6 Sporothrix brasiliensis; 6 S. schenckii; 5 S. mexicana, and 3 S. globosa) in saline at 4°C, and in 10% glycerol plus either 10% lactose or 10% sucrose, at -20°C and -80°C. Viability was assessed after 3, 6, and 9 months of storage, through the recovery of strains on potato dextrose agar and analysis of macro- and micromorphological features. Conidium quantification was performed before and after storage, at 3, 6 and 9 months. 100% viability was observed, regardless of storage conditions or time period. Storage at 4°C and at -20°C did not alter the number of conidia, but lower conidium counts were observed at -80°C. This study shows that the combination of glycerol with lactose or sucrose is effective to maintain Sporothrix spp. at freezing temperatures.

  19. High strain rate deformation of layered nanocomposites

    Science.gov (United States)

    Lee, Jae-Hwang; Veysset, David; Singer, Jonathan P.; Retsch, Markus; Saini, Gagan; Pezeril, Thomas; Nelson, Keith A.; Thomas, Edwin L.

    2012-11-01

    Insight into the mechanical behaviour of nanomaterials under the extreme condition of very high deformation rates and to very large strains is needed to provide improved understanding for the development of new protective materials. Applications include protection against bullets for body armour, micrometeorites for satellites, and high-speed particle impact for jet engine turbine blades. Here we use a microscopic ballistic test to report the responses of periodic glassy-rubbery layered block-copolymer nanostructures to impact from hypervelocity micron-sized silica spheres. Entire deformation fields are experimentally visualized at an exceptionally high resolution (below 10 nm) and we discover how the microstructure dissipates the impact energy via layer kinking, layer compression, extreme chain conformational flattening, domain fragmentation and segmental mixing to form a liquid phase. Orientation-dependent experiments show that the dissipation can be enhanced by 30% by proper orientation of the layers.

  20. Strain driven fast osseointegration of implants

    Directory of Open Access Journals (Sweden)

    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.

  1. Directly probing the effect of strain on magnetic exchange interactions

    Science.gov (United States)

    Dorr, Kathrin

    2012-02-01

    Thin films of transition metal oxides of the perovskite type ABO3 (B = 3d or 4d metal) have revealed abundant examples for strain-driven changes of magnetic ordering. One most popular is the strain-induced ferromagnetic ferroelectric state of otherwise antiferromagnetic paraelectric EuTiO3. Another promising example is the strain control of orbital occupation and magnetic coupling at oxide interfaces of SrRuO3 with manganites. In spite of strong efforts, the theoretical treatment of magnetic exchange in complex oxides has remained a challenge, and experiments continue to show unpredicted / unexplained large effects of the epitaxial strains in films. In order to provide meaningful experimental data on strain dependences, epitaxial thin films should be grown in various coherent strain states on different substrates without changing anything but the strain. This is inherently difficult: possible problems may arise from a strain-dependent oxidation level or microstructure. As a complementary approach, the in-plane strain of epitaxial oxide films can be controlled reversibly using a piezoelectric substrate, even though the accessible reversible strain of 0.1 -- 0.2% is an order of magnitude smaller. In my talk, I will address reversible-strain studies on La0.7Sr0.3MnO3, La1-xSrxCoO3 (x = 0, 0.2, 0.3) und SrRuO3 films, showing the strain response of the magnetic Curie temperature, the magnetization and the electrical resistance and discussing the current understanding of the strain effects on magnetic ordering. In La0.8Sr0.2CoO3, a strain-driven phase transition between ferromagnetic and spin-glass-like could be established by combining the piezoelectric substrate with a tuned buffer system providing varied as-grown strain states. In SrRuO3, a tetragonal tensile strain state shows a suppression of the ordered magnetic moment. Lattice parameters and symmetries of the films were determined by x-ray diffraction. It is noted that the atomic displacements (bond lengths and

  2. Comparative metabolic flux analysis of an Ashbya gossypii wild type strain and a high riboflavin-producing mutant strain.

    Science.gov (United States)

    Jeong, Bo-Young; Wittmann, Christoph; Kato, Tatsuya; Park, Enoch Y

    2015-01-01

    In the present study, we analyzed the central metabolic pathway of an Ashbya gossypii wild type strain and a riboflavin over-producing mutant strain developed in a previous study in order to characterize the riboflavin over-production pathway. (13)C-Metabolic flux analysis ((13)C-MFA) was carried out in both strains, and the resulting data were fit to a steady-state flux isotopomer model using OpenFLUX. Flux to pentose-5-phosphate (P5P) via the pentose phosphate pathway (PPP) was 9% higher in the mutant strain compared to the wild type strain. The flux from purine synthesis to riboflavin in the mutant strain was 1.6%, while that of the wild type strain was only 0.1%, a 16-fold difference. In addition, the flux from the cytoplasmic pyruvate pool to the extracellular metabolites, pyruvate, lactate, and alanine, was 2-fold higher in the mutant strain compared to the wild type strain. This result demonstrates that increased guanosine triphosphate (GTP) flux through the PPP and purine synthesis pathway (PSP) increased riboflavin production in the mutant strain. The present study provides the first insight into metabolic flux through the central carbon pathway in A. gossypii and sets the foundation for development of a quantitative and functional model of the A. gossypii metabolic network.

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

    Directory of Open Access Journals (Sweden)

    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. Difficulties in identifying Klebsiella strains of clinical origin.

    Science.gov (United States)

    Monnet, D; Freney, J; Brun, Y; Boeufgras, J M; Fleurette, J

    1991-01-01

    Two hundred and four strains of Gram-negative bacteria of clinical origin, initially identified as Klebsiella using the API 20 E system, and 10 reference strains were further analysed with the API 20 EC test system and the API 50 CH, API 50 AO, API 50 AA assimilation systems. Four clusters corresponding to the species Klebsiella pneumoniae subsp. pneumoniae, K. oxytoca, K. planticola, and K. terrigena were formed after numerical analysis of 155 selected tests and the 26 most discriminating tests were determined. A comparison was made between conventional identification using the API 20 E system and the results of the numerical analysis. The conventional method resulted in incorrect identification of 13% of the strains tested, especially for the new species: K. planticola and K. terrigena. After numerical analysis, 17 out of 204 strains (8.3%) of clinical origin were identified as K. planticola. Only 1 strain of clinical origin was identified as K. terrigena, and 1 strain as K. ornithinolytica.

  5. Antimicrobial substances produced by coliform strains active against foodborne pathogens.

    Science.gov (United States)

    Fleming, Luana Rocha; Bolzan, Dayana Nascimento; Nascimento, Janaína Dos Santos

    2010-03-01

    In the present study, 31 coliform strains were isolated from salad, cheese, and meat products sold in commercial establishments in Rio de Janeiro city, and were tested for antibiotic resistance and antimicrobial substance production. Thirteen strains (41.9%) were resistant to at least one antibiotic tested, among which one presented resistance to nine different antibiotics. Two strains (6.4%) exhibited inhibitory activity against the indicator strains, Escherichia coli LMIFRJ and Salmonella enterica I. The antimicrobial substances that they produced were sensitive to proteolytic enzymes, suggesting that they might be bacteriocins. The producer strains were identified as Klebsiella ozaenae and Raoultella terrigena. Although they had similar spectrums of action, the bacteriocins were shown to be different. Both of them were able to inhibit E. coli, Klebsiella, Enterobacter, and Salmonella strains, including antibiotic-resistant ones. Our results suggest that these bacteriocins, named klebicin K and raoultellin L, could have potential use against some foodborne pathogens.

  6. Ultra-responsive soft matter from strain-stiffening hydrogels

    Science.gov (United States)

    Jaspers, Maarten; Dennison, Matthew; Mabesoone, Mathijs F. J.; Mackintosh, Frederick C.; Rowan, Alan E.; Kouwer, Paul H. J.

    2014-12-01

    The stiffness of hydrogels is crucial for their application. Nature’s hydrogels become stiffer as they are strained. This stiffness is not constant but increases when the gel is strained. This stiffening is used, for instance, by cells that actively strain their environment to modulate their function. When optimized, such strain-stiffening materials become extremely sensitive and very responsive to stress. Strain stiffening, however, is unexplored in synthetic gels since the structural design parameters are unknown. Here we uncover how readily tuneable parameters such as concentration, temperature and polymer length impact the stiffening behaviour. Our work also reveals the marginal point, a well-described but never observed, critical point in the gelation process. Around this point, we observe a transition from a low-viscous liquid to an elastic gel upon applying minute stresses. Our experimental work in combination with network theory yields universal design principles for future strain-stiffening materials.

  7. Strain phase separation: Formation of ferroelastic domain structures

    Science.gov (United States)

    Xue, Fei; Li, Yongjun; Gu, Yijia; Zhang, Jinxing; Chen, Long-Qing

    2016-12-01

    Phase decomposition is a well-known process leading to the formation of two-phase mixtures. Here we show that a strain imposed on a ferroelastic crystal promotes the formation of mixed phases and domains, i.e., strain phase separation with local strains determined by a common tangent construction on the free energy versus strain curves. It is demonstrated that a domain structure can be understood using the concepts of domain/phase rule, lever rule, and coherent and incoherent strain phase separation, in a complete analogy to phase decomposition. The proposed strain phase separation model is validated using phase-field simulations and experimental observations of PbTi O3 and BiFe O3 thin films as examples. The proposed model provides a simple tool to guide and design domain structures of ferroelastic systems.

  8. Comparison of four molecular methods to type Salmonella Enteritidis strains.

    Science.gov (United States)

    Campioni, Fábio; Pitondo-Silva, André; Bergamini, Alzira M M; Falcão, Juliana P

    2015-05-01

    This study compared the pulsed-field gel electrophoresis (PFGE), enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR), multilocus variable-number of tanden-repeat analysis (MLVA), and multilocus sequence typing (MLST) methods for typing 188 Salmonella Enteritidis strains from different sources isolated over a 24-year period in Brazil. PFGE and ERIC-PCR were more efficient than MLVA for subtyping the strains. However, MLVA provided additional epidemiological information for those strains. In addition, MLST showed the Brazilian strains as belonging to the main clonal complex of S. Enteritidis, CC11, and provided the first report of two new STs in the S. enterica database but could not properly subtype the strains. Our results showed that the use of PFGE or ERIC-PCR together with MLVA is suitable to efficiently subtype S. Enteritidis strains and provide important epidemiological information.

  9. Strain Engineering to Modify the Electrochemistry of Energy Storage Electrodes

    Science.gov (United States)

    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

  10. Strain-induced negative differential resistance in ultrasmall carbon nanotube

    Science.gov (United States)

    Fang, Hui; Zhang, Fei-Peng; Ruan, Xing-Xiang; Huang, Can-Sheng; Jiang, Zhi-Nian; Peng, Jin-Yun; Wang, Ru-Zhi

    2017-08-01

    The transport properties in ultrasmall single-wall carbon nanotubes (SWCNTs) under tensile strain have been theoretically investigated. The regular negative differential resistance (NDR) induced by the strain undergoes a process from enhancement to weakening in the zigzag (3,0) SWCNT. The NDR achieves maximum with applying 4% tensile strain. Compared to the case of (3,0) SWCNT, that NDR cannot be manipulated by applying strain clearly in (4,0) and (5,0) ultrasmall SWCNTs with tensile strain lower than 10%. It proposes this strain-induced NDR effect to demonstrate the possibility of finding potential applications in SWCNT-based NDR nanodevices such as in memory devices, oscillators and fast switching devices.

  11. Isolation of clinical strains of Pseudomonas aeruginosa harboring different plasmids.

    Science.gov (United States)

    Ranjbar, R; Owlia, P; Saderi, H; Bameri, Z; Izadi, M; Jonaidi, N; Morovvati, S

    2007-09-01

    Aim of this study was to investigate the presence of plasmids among the strains of P. aeruginosa isolated from clinically diagnosed cases in Tehran in 2006. A total of 38 strains of P. aeruginosa were isolated. With the exception of one isolate, all P. aeruginosa strains harbored at least one plasmid band. The electrophoretic analysis of plasmid DNAs showed different number of plasmid bands among the strains tested. The DNA band of 1.4 kbp was evident in 84.2% of the strains. Approximately 71 and 21% of the isolates harbored concomitantly two and three plasmids, respectively. Isolation of strains with diverse types of plasmids suggests the different cluster of P. aeruginosa might be disseminated during the current study period.

  12. Evolutionary perspective on the origin of Haitian cholera outbreak strain.

    Science.gov (United States)

    Dasgupta, Anirban; Banerjee, Rachana; Das, Santasabuj; Basak, Surajit

    2012-01-01

    Cholera epidemic has not been reported in Haiti for at least 100 years, although cholera has been present in Latin America since 1991. Surprisingly, the recent cholera epidemic in Haiti (October 2010) recorded more than 250,000 cases and 4000 deaths in the first 6 months and became one of the most explosive and deadly cholera outbreak in recent history. In the present study, we conducted genomic analyses of pathogenicity islands of three Haitian Vibrio cholerae strains and compared them with nine different V. cholerae O1 El Tor genomes. Although CIRS101 is evolutionarily most similar to the Haitian strains, our study also provides some important differences in the genetic organization of pathogenicity islands of Haitian strains with CIRS101. Evolutionary analysis suggests that unusual functional constraints have been imposed on the Haitian strains and we hypothesize that amino acid substitution is more deleterious in Haitian strains than in nonHaitian strains.

  13. High Strain Rate Compressive Tests on Woven Graphite Epoxy Composites

    Science.gov (United States)

    Allazadeh, Mohammad Reza; Wosu, Sylvanus N.

    2011-08-01

    The behavior of composite materials may be different when they are subjected to high strain rate load. Penetrating split Hopkinson pressure bar (P-SHPB) is a method to impose high strain rate on specimen in the laboratory experiments. This research work studied the response of the thin circular shape specimens, made out of woven graphite epoxy composites, to high strain rate impact load. The stress-strain relationships and behavior of the specimens were investigated during the compressive dynamic tests for strain rates as high as 3200 s-1. One dimensional analysis was deployed for analytical calculations since the experiments fulfilled the ratio of diameter to length of bars condition in impact load experiments. The mechanics of dynamic failure was studied and the results showed the factors which govern the failure mode in high strain deformation via absorbed energy by the specimen. In this paper, the relation of particle velocity with perforation depth was discussed for woven graphite epoxy specimens.

  14. Preparation of dodecanol-tolerant strains of Yarrowia lipolytica.

    Science.gov (United States)

    Smit, Martha S; Mokgoro, Masego M; Setati, Evodia; Nicaud, Jean-Marc

    2004-05-01

    Dodecanol (1% v/v) and dodecanoic acid (1% w/v) inhibited growth of Yarrowia lipolytica in complex media supplemented with glucose but dodecanedioic acid (1% w/v) was not toxic. Dodecanol-tolerant strains were prepared from the wild type strain H222 as well as the acyl-CoA oxidase deleted (deltaPOX2, POX3, POX5) strain MTLY35. These strains grew in rich media containing up to 10% (v/v) dodecanol. Dodecanol-tolerant strains remained dodecanol tolerant after they had been cultured in rich media without dodecanol. No significant amount of dodecanedioic acid was accumulated by the dodecanol-tolerant strains when grown on glucose in the presence of dodecanol.

  15. Genomic and gene variation in Mycoplasma hominis strains

    DEFF Research Database (Denmark)

    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...

  16. Environment Identification in Flight using Sparse Approximation of Wing Strain

    CERN Document Server

    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...

  17. Atrial Strain and Strain Rate: A Novel Method for the Evaluation of Atrial Stunning

    Science.gov (United States)

    Ozkan, Hakan; Binici, Suleyman; Tenekecioglu, Erhan; Ari, Hasan; Bozat, Tahsin

    2016-01-01

    Background Atrial fibrillation (AF) is the most common arrhythmia seen in adults. Atrial stunning is defined as the temporary mechanical dysfunction of the atrial appendage developing after AF has returned to sinus rhythm (SR). Objectives We aimed to evaluate atrial contractile functions by strain and strain rate in patients with AF, following pharmacological and electrical cardioversion and to compare it with conventional methods. Methods This study included 41 patients with persistent AF and 35 age-matched control cases with SR. All the AF patients included in the study had transthoracic and transesophageal echocardiography performed before and after. Septum (SEPsSR), left atrium (LAsSR) and right atrium peak systolic strain rate (RAsSR) were defined as the maximum negative value during atrial contraction and septum (SEPε), left atrium (LAε) and right atrium peak systolic strain (RAε) was defined as the percentage of change. Parameters of two groups were compared. Results In the AF group, 1st hour and 24th hour LAε, RAε, SEPε, LAsSR, RAsSR, SEPsSR found to be significantly lower than in the control group (LAε: 2.61%±0.13, 3.06%±0.19 vs 6.45%±0.27, p<0.0001; RAε: 4.03%±0.38, 4.50%±0.47 vs 10.12%±0.64, p<0.0001; SEPε: 3.0%±0.22, 3.19%±0.15 vs 6.23%±0.49, p<0.0001; LAsSR: 0.61±0.04s-1, 0.75±0.04s-1 vs 1.35±0.04s-1, p<0.0001; RAsSR: 1.13±0.06s-1, 1.23±0.07s-1 vs 2.10±0.08s- 1, p<0.0001; SEPsSR: 0.76±0.04s- 1, 0.78±0.04s- 1 vs 1.42±0.06 s- 1, p<0.0001). Conclusion Atrial strain and strain rate parameters are superior to conventional echocardiographic parameters for the evaluation of atrial stunning in AF cases where SR has been achieved. PMID:27627221

  18. "Behaviour changes in Permethrin-resistant strain of Anopheles Stephensi "

    Directory of Open Access Journals (Sweden)

    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.

  19. Strain Hardening of Polymer Glasses: Entanglements, Energetics, and Plasticity

    OpenAIRE

    Hoy, Robert S.; Robbins, Mark O.

    2007-01-01

    Simulations are used to examine the microscopic origins of strain hardening in polymer glasses. While stress-strain curves for a wide range of temperature can be fit to the functional form predicted by entropic network models, many other results are fundamentally inconsistent with the physical picture underlying these models. Stresses are too large to be entropic and have the wrong trend with temperature. The most dramatic hardening at large strains reflects increases in energy as chains are ...

  20. AERODYNAMIC BEHAVIOR AIRCRAFT CAUSED BY RESIDUAL STRAIN WINGS

    Directory of Open Access Journals (Sweden)

    Sergiy Ishchenko

    2011-03-01

    Full Text Available Abstract. The influence of residual strain on the airframe aerodynamic characteristics of aircraft wasconsidered. The possibility of estimation of changes in deformation of airframe using data of leveling wasshown. The method of estimating the change of aerodynamic characteristics caused by the influence ofresidual strain airframe was proposed. Technique can be used in the operation and overhaul of aircraft withlarge operating time.Keywords: aerodynamic characteristics, residual strain construction asymmetric moments, thedistribution of circulation, the scheme of leveling, trigonometric series.