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Sample records for acidithiobacillus ferrooxidans strains

  1. Zinc bioleaching from an iron concentrate using Acidithiobacillus ferrooxidans strain from Hercules Mine of Coahuila, Mexico

    NASA Astrophysics Data System (ADS)

    Núñez-Ramírez, Diola Marina; Solís-Soto, Aquiles; López-Miranda, Javier; Pereyra-Alférez, Benito; Rutiaga-Quiñónes, Miriam; Medina-Torres, Luis; Medrano-Roldán, Hiram

    2011-10-01

    The iron concentrate from Hercules Mine of Coahuila, Mexico, which mainly contained pyrite and pyrrhotite, was treated by the bioleaching process using native strain Acidithiobacillus ferrooxidans ( A. ferrooxidans) to determine the ability of these bacteria on the leaching of zinc. The native bacteria were isolated from the iron concentrate of the mine. The bioleaching experiments were carried out in shake flasks to analyze the effects of pH values, pulp density, and the ferrous sulfate concentration on the bioleaching process. The results obtained by microbial kinetic analyses for the evaluation of some aspects of zinc leaching show that the native bacteria A. ferrooxidans, which is enriched with a 9K Silverman medium under the optimum conditions of pH 2.0, 20 g/L pulp density, and 40 g/L FeSO4, increases the zinc extraction considerably observed by monitoring during15 d, i.e., the zinc concentration has a decrease of about 95% in the iron concentrate.

  2. Differential gene expression in response to copper in Acidithiobacillus ferrooxidans strains possessing dissimilar copper resistance.

    PubMed

    Wu, Xueling; Hu, Qi; Hou, Dongmei; Miao, Bo; Liu, Xueduan

    2010-01-01

    Locus afe_0454 from Acidithiobacillus ferrooxidans (At.ferrooxidans) is annotated as related to copper resistance in The Institute for Genomic Research database. In our study, two At.ferrooxidans strains, 26(#) and DC, with different levels of copper ion resistance were isolated from acid mine drainages at two major copper mines in China, and their copper-resistance capacity was determined. The 26(#) strain had a copper-tolerance level of 0.22 mol/L, whereas the DC strain had a lower copper-tolerance level of 0.04 mol/L. The mutant 26(#) was generated from strain 26(#), and its copper-tolerance level was 0.25 mol/L. Using real-time quantitative reverse transcription polymerase chain reaction, differential expression of the afe_0454 gene during copper ion stress of these three strains was investigated. The results showed that the expression of afe_0454 was increased under copper ion stress, indicating that the afe_0454 gene is sensitive to copper levels. Furthermore, the afe_0454 gene expression ratio varied in the different copper-resistant strains. Gene expression was highest in the highest copper-resistant strain. The deduced amino acid sequence of the afe_0454 gene was 56.87% non-polar, indicating the AFE_0454 protein was hydrophobic. Searching with the AFE_0454 protein in The Institute for Genomic Research database showed that the structure of the copper resistance protein D (CopD), which transports copper ions outside of the cell, had the highest sequence identity (46%). Bioinformatics analysis showed that the AFE_0454 protein has eight transmembrane helixes and was predicted to be localized to the plasma membrane. These results strongly suggested that the AFE_0454 protein is likely a transmembrane protein and might be directly involved in copper ion resistance.

  3. Identification and characterization of four strains of Acidithiobacillus ferrooxidans isolated from different sites in China.

    PubMed

    Chen, Hong; Yang, Bo; Chen, Xinhua

    2009-01-01

    Four strains of Acidithiobacillus ferrooxidans (A. ferrooxidans), AF1, AF2, AF3 and AFc, were isolated from samples with different geological sources using a 9K medium. These four isolates were identified as A. ferrooxidans by phenotypic and 16S rDNA sequence analyses. All four isolates were able to use ferrous ion (Fe(2+)), elemental sulfur (S0) or pyrite as a sole energy source, but they showed differences in pH optima and range of activity, optimum temperature of activity, resistance to chloride (KCl) and heavy metal ions, and oxidation rates of Fe(2+), S0 and pyrite. AF3 was the most active strain when using Fe(2+) as the energy source, while AFc grew best using pyrite as the energy source. AF2 appeared to differ from the other three strains in substrate utilization, as it oxidizes S0 and pyrite more effectively than Fe(2+). RAPD analysis of genomic DNA from these isolates showed that banding profiles of their genomic DNA exhibited some differences, and the genomic banding profile of AF2 was significantly different from that of others. To obtain an insight into the molecular biology of the process of the energy production of these strains, several genes involved in the iron respiratory chain were cloned and sequenced, including Fe(2+) oxidase (iro), rusticyanin (rus) and subunit III of aa3-type cytochrome oxidase (cox C) genes. The results revealed that the iro gene can be cloned from all of the four strains and the nucleotide sequences were shown to be completely identical in each. However, rus and coxC genes could be amplified only from AF1, AF3 and AFc, not from AF2. These results suggested that the phenotypic differences of the four strains of A. ferrooxidans from different sites correlated with their genetic polymorphism, which may result from the different environments in which they lived, and that the strain AF2 was phenotypically and genetically significantly different from the other three strains.

  4. Reduction of Hg2+ with reduced mammalian cytochrome c by cytochrome c oxidase purified from a mercury-resistant acidithiobacillus ferrooxidans strain, MON-1.

    PubMed

    Sugio, Tsuyoshi; Fujii, Mitsuko; Ninomiya, Yumika; Kanao, Tadayoshi; Negishi, Atsunori; Takeuchi, Fumiaki

    2008-07-01

    Acidithiobacillus ferrooxidans AP19-3, ATCC 23270, and MON-1 are mercury-sensitive, moderately mercury-resistant, and highly mercury-resistant strains respectively. It is known that 2,3,5,6-tetramethyl-p-phenylendiamine (TMPD) and reduced cytochrome c are used as electron donors specific for cytochrome c oxidase. Resting cells of strain MON-1 had TMPD oxidase activity and volatilized metal mercury with TMPD as an electron donor. Cytochrome c oxidase purified from strain MON-1 reduced mercuric ions to metalic mercury with reduced mammalian cytochrome c as well as TMPD. These mercury volatilization activities with reduced cytochrome c and TMPD were completely inhibited by 1 mM NaCN. These results indicate that cytochrome c oxidase is involved in mercury reduction in A. ferrooxidans cells. The cytochrome c oxidase activities of strains AP19-3 and ATCC 23270 were completely inhibited by 1 muM and 5 muM of mercuric chloride respectively. In contrast, the activity of strain MON-1 was inhibited 33% by 5 muM, and 70% by 10 muM of mercuric chloride, suggesting that the levels of mercury resistance in A. ferrooxidans strains correspond well with the levels of mercury resistance of cytochrome c oxidase.

  5. Analysis of the surface proteins of Acidithiobacillus ferrooxidans strain SP5/1 and the new, pyrite-oxidizing Acidithiobacillus isolate HV2/2, and their possible involvement in pyrite oxidation.

    PubMed

    Klingl, Andreas; Moissl-Eichinger, Christine; Wanner, Gerhard; Zweck, Josef; Huber, Harald; Thomm, Michael; Rachel, Reinhard

    2011-12-01

    Two strains of rod-shaped, pyrite-oxidizing acidithiobacilli, their cell envelope structure and their interaction with pyrite were investigated in this study. Cells of both strains, Acidithiobacillus ferrooxidans strain SP5/1 and the moderately thermophilic Acidithiobacillus sp. strain HV2/2, were similar in size, with slight variations in length and diameter. Two kinds of cell appendages were observed: flagella and pili. Besides a typical Gram-negative cell architecture with inner and outer membrane, enclosing a periplasm, both strains were covered by a hitherto undescribed, regularly arranged 2-D protein crystal with p2-symmetry. In A. ferrooxidans, this protein forms a stripe-like structure on the surface. A similar surface pattern with almost identical lattice vectors was also seen on the cells of strain HV2/2. For the surface layer of both bacteria, a direct contact to pyrite crystals was observed in ultrathin sections, indicating that the S-layer is involved in maintaining this contact site. Observations on an S-layer-deficient strain show, however, that cell adhesion does not strictly depend on the presence of the S-layer and that this surface protein has an influence on cell shape. Furthermore, the presented data suggest the ability of the S-layer protein to complex Fe3+ ions, suggesting a role in the physiology of the microorganisms.

  6. Ferric iron uptake genes are differentially expressed in the presence of copper sulfides in Acidithiobacillus ferrooxidans strain LR.

    PubMed

    Ferraz, Lúcio F C; Verde, Leandro C L; Vicentini, Renato; Felício, Ana P; Ribeiro, Marcelo L; Alexandrino, Fabiana; Novo, Maria T M; Garcia, Oswaldo; Rigden, Daniel J; Ottoboni, Laura M M

    2011-03-01

    Acidithiobacillus ferrooxidans is one of the most widely used microorganisms in bioleaching operations to recover copper from low-grade copper sulfide ores. This work aimed to investigate the relative expression of genes related to the iron uptake system when A. ferrooxidans LR was maintained in contact with chalcopyrite or bornite as the sole energy source. Real-time quantitative PCR analysis revealed that the presence of bornite had no effect on the expression of seven genes related to the siderophore-mediated Fe(III) uptake system, while in the presence of chalcopyrite the expression of the genes was up-regulated. Bioinformatic analysis of the genomic region where these genes were found revealed the existence of three new putative DNA-binding sequences for the ferric iron uptake transcriptional regulator (Fur). Electrophoretic mobility shift assays demonstrated that a purified A. ferrooxidans His-tagged Fur protein was able to bind in vitro to each of these putative Fur boxes, suggesting that Fur regulated the expression of these genes. The expression of fur and two known Fur-regulated genes, mntH and dsrK, was also investigated in the presence of chalcopyrite. While the expression of fur and mntH was up-regulated, the expression of dsrK was down-regulated. The low amount of ferrous iron in the medium was probably responsible for the up-regulation of fur and the genes related to the siderophore-mediated Fe(III) uptake system when A. ferrooxidans LR was kept in the presence of chalcopyrite. A homology model of the A. ferrooxidans Fur was constructed and revealed that the putative DNA-binding surface presents conserved positively charged residues, supporting a previously suggested mode of interaction with DNA. The up-regulation of fur and the siderophore-mediated Fe(III) uptake genes, and the down-regulation of dsrK suggest that in the presence of chalcopyrite Fur acts as a transcription inducer and repressor.

  7. Impact of solvent extraction organics on bioleaching by Acidithiobacillus ferrooxidans

    NASA Astrophysics Data System (ADS)

    Yu, Hualong; Liu, Xiaorong; Shen, Junhui; Chi, Daojie

    2017-03-01

    Solvent extraction organics (SX organics) entrained and dissoluted in the raffinate during copper SX operation, can impact bioleaching in case of raffinate recycling. The influence of SX organics on bioleaching process by Acidithiobacillus ferrooxidans (At. ferrooxidans) has been investigated. The results showed that, cells of At. ferrooxidans grew slower with contaminated low-grade chalcopyrite ores in shaken flasks bioleaching, the copper bioleaching efficiency reached 15%, lower than that of 24% for uncontaminated minerals. Obviously, the SX organics could adsorb on mineral surface and hinder its contact with bacterials, finanlly lead to the low bioleaching efficiency.

  8. Acidithiobacillus ferrooxidans metabolism: from genome sequence to industrial applications

    PubMed Central

    Valdés, Jorge; Pedroso, Inti; Quatrini, Raquel; Dodson, Robert J; Tettelin, Herve; Blake, Robert; Eisen, Jonathan A; Holmes, David S

    2008-01-01

    Background Acidithiobacillus ferrooxidans is a major participant in consortia of microorganisms used for the industrial recovery of copper (bioleaching or biomining). It is a chemolithoautrophic, γ-proteobacterium using energy from the oxidation of iron- and sulfur-containing minerals for growth. It thrives at extremely low pH (pH 1–2) and fixes both carbon and nitrogen from the atmosphere. It solubilizes copper and other metals from rocks and plays an important role in nutrient and metal biogeochemical cycling in acid environments. The lack of a well-developed system for genetic manipulation has prevented thorough exploration of its physiology. Also, confusion has been caused by prior metabolic models constructed based upon the examination of multiple, and sometimes distantly related, strains of the microorganism. Results The genome of the type strain A. ferrooxidans ATCC 23270 was sequenced and annotated to identify general features and provide a framework for in silico metabolic reconstruction. Earlier models of iron and sulfur oxidation, biofilm formation, quorum sensing, inorganic ion uptake, and amino acid metabolism are confirmed and extended. Initial models are presented for central carbon metabolism, anaerobic metabolism (including sulfur reduction, hydrogen metabolism and nitrogen fixation), stress responses, DNA repair, and metal and toxic compound fluxes. Conclusion Bioinformatics analysis provides a valuable platform for gene discovery and functional prediction that helps explain the activity of A. ferrooxidans in industrial bioleaching and its role as a primary producer in acidic environments. An analysis of the genome of the type strain provides a coherent view of its gene content and metabolic potential. PMID:19077236

  9. Kinetics of pyrite, pyrrhotite, and chalcopyrite dissolution by Acidithiobacillus ferrooxidans.

    PubMed

    Kocaman, Ayse Tuba; Cemek, Mustafa; Edwards, Katrina Jane

    2016-08-01

    The main objective of this study was to investigate the dissolution kinetics of pyrite, pyrrhotite, and chalcopyrite. Crushed minerals were reacted with Acidithiobacillus ferrooxidans (25 °C). The kinetics of dissolution was investigated by monitoring pH and Fe(2+) and Fe(3+) ion concentrations in the leaching solutions. Pyrite, pyrrhotite, and chalcopyrite dissolution by A. ferrooxidans was found to be a chemically controlled process. With bacteria, the dissolution rates of the minerals increased in the order of pyrrhotite, pyrite, and chalcopyrite. The number of cells attached to mineral surfaces increased in the same order. Acidithiobacillus ferrooxidans was found to enhance the dissolution rates of the minerals. The acid-insoluble trait of pyrite and acid-soluble trait of the other 2 minerals affected the pH changes in the leaching solutions.

  10. Compensation phenomena found in Acidithiobacillus ferrooxidans after starvation stress.

    PubMed

    Tu, Bowen; Li, Juan; Guo, Yueshuai; Guo, Xuejiang; Lu, Xiancai; Han, Xiaodong

    2014-06-01

    Acidithiobacillus ferrooxidans showed the compensate growth and oxidation after re-feeding with sufficient ferrous materials after starvation. Compensatory phenomena were first detected in chemoautotrophic organisms. Starvation stress of Acidithiobacillus ferrooxidans was achieved via culturing in low concentrations of iron. During compensation, growth and ferrous oxidation took place faster than in controls. In addition, some genes related to ferrous oxidation (such as rus) and carbon assimilation (cbbR, csoS3) were expressed in different patterns in the low energy environments. Their expression patterns can account for this increased growth and oxidation. Other groups of genes (cspAB, feoAB, fur) were suppressed in response to starvation stress. The presence of pyrite and joint cold stress can render compensation nearly undetectable. This may be why the compensation phenomena observed under these conditions was not the same as that observed under single starvation stress conditions. Gene expression reflected a possible mechanism of tolerance to starvation in Acidithiobacillus ferrooxidans, which would allow the organism to adapt and survive in ferrous-limited environments.

  11. Reduction of vanadium(V) with Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans.

    PubMed

    Bredberg, Katarina; Karlsson, Hans T; Holst, Olle

    2004-03-01

    Biotechnological leaching has been proposed as a suitable method for extraction of vanadium from spent catalysts and oil ash. In the biological leaching process, the vanadium(V) can be reduced to vanadium(IV), which is a less toxic and more soluble form of the vanadium. The present investigation showed that Acidithiobacillus ferrooxidans efficiently reduced vanadium(V) in the form of vanadium pentaoxide, to vanadyl(IV) ions, and tolerated high concentrations of vanadium(IV) and vanadium(V). A. ferrooxidans was compared with Acidithiobacillus thiooxidans, which has previously been utilized for vanadium leaching and reduction. Vanadium pentaoxide and sodium vanadate were used as model compounds. The results of this study indicate possibilities to develop an economical and technically feasible process for biotechnological vanadium recovery.

  12. Inter- and intraspecific genomic variability of the 16S-23S intergenic spacer regions (ISR) in representatives of Acidithiobacillus thiooxidans and Acidithiobacillus ferrooxidans.

    PubMed

    Ni, Yong-Qing; Yang, Yuan; Bao, Jing-Ting; He, Kai-Yu; Li, Hong-Yu

    2007-05-01

    The complete sequences of 32 intergenic spacer regions (ISR) from Acidithiobacillus strains, including 29 field strains isolated from coal, copper, molybdenum mine wastes or sediment of different geoclimatic regions in China, reference strain ATCC19859 and the type strains of the two species were determined. These data, together with other sequences available in the GenBank database, were used to carry out the first detailed assessment of the inter- and intraspecific genomic variability of the ISR sequences and to infer phylogenetic relationships within the genus. The total length of the 16S-23S rRNA intergenic spacer regions of the Acidithiobacillus thiooxidans and Acidithiobacillus ferrooxidans strains ranged from 451 to 490 bp, and from 434 to 456 bp, respectively. The degree of intrageneric ISR sequence similarity was higher than the degree of intergeneric similarity, and the overall similarity values of the ISRs varied from 60.49% to 84.71% between representatives of different species of the genus Acidithiobacillus. Sequences from the spacer of the A. thiooxidans and A. ferrooxidans strains ranged from 86.71% to 99.56% and 92.36% to 100% similarity, respectively. All Acidithiobacillus strains were separated into three phylogenetic major clusters and seven phylogenetic groups. ISR may be a potential target for the development of in situ hybridization probe aimed at accurately detecting acidithiobacilli in the various acidic environments.

  13. Differential gene expression and bioinformatics analysis of copper resistance gene afe_1073 in Acidithiobacillus ferrooxidans.

    PubMed

    Hu, Qi; Wu, Xueling; Jiang, Ying; Liu, Yuandong; Liang, Yili; Liu, Xueduan; Yin, Huaqun; Baba, Ngom

    2013-04-01

    Copper resistance of acidophilic bacteria is very significant in bioleaching of copper ore since high concentration of copper are harmful to the growth of organisms. Copper resistance gene afe_1073 was putatively considered to be involved in copper homeostasis in Acidithiobacillus ferrooxidans ATCC23270. In the present study, differential expression of afe_1073 in A. ferrooxidans strain DY26 and DC was assessed with quantitative reverse transcription polymerase chain reaction. The results showed the expression of afe_1073 in two strains increased with the increment of copper concentrations. The expression of DY26 was lower than that of DC at the same copper concentration although A. ferrooxidans strain DY26 possessed higher copper resistance than strain DC. In addition, bioinformatics analysis showed AFE_1073 was a typical transmembrane protein P1b1-ATPase, which could reduce the harm of Cu(+) by pumping it out from the cell. There were two mutation sites in AFE_1073 between DY26 and DC and one may change the hydrophobicity of AFE_1073, which could enhance the ability of DY26 to pump out Cu(+). Therefore, DY26 needed less gene expression of afe_1073 for resisting copper toxicity than that of DC at the same copper stress. Our study will be beneficial to understanding the copper resistance mechanism of A. ferrooxidans.

  14. A genomic island provides Acidithiobacillus ferrooxidans ATCC 53993 additional copper resistance: a possible competitive advantage.

    PubMed

    Orellana, Luis H; Jerez, Carlos A

    2011-11-01

    There is great interest in understanding how extremophilic biomining bacteria adapt to exceptionally high copper concentrations in their environment. Acidithiobacillus ferrooxidans ATCC 53993 genome possesses the same copper resistance determinants as strain ATCC 23270. However, the former strain contains in its genome a 160-kb genomic island (GI), which is absent in ATCC 23270. This GI contains, amongst other genes, several genes coding for an additional putative copper ATPase and a Cus system. A. ferrooxidans ATCC 53993 showed a much higher resistance to CuSO(4) (>100 mM) than that of strain ATCC 23270 (<25 mM). When a similar number of bacteria from each strain were mixed and allowed to grow in the absence of copper, their respective final numbers remained approximately equal. However, in the presence of copper, there was a clear overgrowth of strain ATCC 53993 compared to ATCC 23270. This behavior is most likely explained by the presence of the additional copper-resistance genes in the GI of strain ATCC 53993. As determined by qRT-PCR, it was demonstrated that these genes are upregulated when A. ferrooxidans ATCC 53993 is grown in the presence of copper and were shown to be functional when expressed in copper-sensitive Escherichia coli mutants. Thus, the reason for resistance to copper of two strains of the same acidophilic microorganism could be determined by slight differences in their genomes, which may not only lead to changes in their capacities to adapt to their environment, but may also help to select the more fit microorganisms for industrial biomining operations.

  15. Toxin-antitoxin systems in the mobile genome of Acidithiobacillus ferrooxidans.

    PubMed

    Bustamante, Paula; Tello, Mario; Orellana, Omar

    2014-01-01

    Toxin-antitoxin (TA) systems are genetic modules composed of a pair of genes encoding a stable toxin and an unstable antitoxin that inhibits toxin activity. They are widespread among plasmids and chromosomes of bacteria and archaea. TA systems are known to be involved in the stabilization of plasmids but there is no consensus about the function of chromosomal TA systems. To shed light on the role of chromosomally encoded TA systems we analyzed the distribution and functionality of type II TA systems in the chromosome of two strains from Acidithiobacillus ferrooxidans (ATCC 23270 and 53993), a Gram-negative, acidophilic, environmental bacterium that participates in the bioleaching of minerals. As in other environmental microorganisms, A. ferrooxidans has a high content of TA systems (28-29) and in twenty of them the toxin is a putative ribonuclease. According to the genetic context, some of these systems are encoded near or within mobile genetic elements. Although most TA systems are shared by both strains, four of them, which are encoded in the active mobile element ICEAfe1, are exclusive to the type strain ATCC 23270. We demonstrated that two TA systems from ICEAfe1 are functional in E. coli cells, since the toxins inhibit growth and the antitoxins counteract the effect of their cognate toxins. All the toxins from ICEAfe1, including a novel toxin, are RNases with different ion requirements. The data indicate that some of the chromosomally encoded TA systems are actually part of the A. ferrooxidans mobile genome and we propose that could be involved in the maintenance of these integrated mobile genetic elements.

  16. Cr and Ni recovery during bioleaching of dewatered metal-plating sludge using Acidithiobacillus ferrooxidans.

    PubMed

    Rastegar, S O; Mousavi, S M; Shojaosadati, S A

    2014-09-01

    This study determined the optimal conditions required to attain maximum metal recovery in the bioleaching process of dewatered metal-plating sludge using Acidithiobacillus ferrooxidans (A. ferrooxidans). Adaptation of this strain was carried up to 1% (w/v) of the sample. Three factors including initial pH, initial Fe(3+) concentration and pulp density were selected as the effective factors and were optimized using a central composite design of response surface methodology. An initial pH of 1, pulp density of 9 g/l and initial Fe(3+) concentration of 1g/l were determined to be optimum values by the statistical models. The highest extractions for Cr and Ni under optimal conditions were 55.6% and 58.2%, respectively. Bioleaching kinetics was investigated using a modified shrinking core model to better understand the mechanism of the leaching reaction. The model predictions indicate that the diffusion step controlled the overall dissolution kinetics and is the rate controlling step.

  17. Growth of the acidophilic iron-sulfur bacterium Acidithiobacillus ferrooxidans under Mars-like geochemical conditions

    NASA Astrophysics Data System (ADS)

    Bauermeister, Anja; Rettberg, Petra; Flemming, Hans-Curt

    2014-08-01

    The question of life on Mars has been in focus of astrobiological research for several decades, and recent missions in orbit or on the surface of the planet are constantly expanding our knowledge on Martian geochemistry. For example, massive stratified deposits have been identified on Mars containing sulfate minerals and iron oxides, which suggest the existence of acidic aqueous conditions in the past, similar to acidic iron- and sulfur-rich environments on Earth. Acidophilic organisms thriving in such habitats could have been an integral part of a possibly widely extinct Martian ecosystem, but remains might possibly even exist today in protected subsurface niches. The chemolithoautotrophic strain Acidithiobacillus ferrooxidans was selected as a model organism to study the metabolic capacities of acidophilic iron-sulfur bacteria, especially regarding their ability to grow with in situ resources that could be expected on Mars. The experiments were not designed to accurately simulate Martian physical conditions (except when certain single parameters such as oxygen partial pressure were considered), but rather the geochemical environment that can be found on Mars. A. ferrooxidans could grow solely on the minerals contained in synthetic Mars regolith mixtures with no added nutrients, using either O2 as an external electron acceptor for iron oxidation, or H2 as an external electron donor for iron reduction, and thus might play important roles in the redox cycling of iron on Mars. Though the oxygen partial pressure of the Martian atmosphere at the surface was not sufficient for detectable iron oxidation and growth of A. ferrooxidans during short-term incubation (7 days), alternative chemical O2-generating processes in the subsurface might yield microhabitats enriched in oxygen, which principally are possible under such conditions. The bacteria might also contribute to the reductive dissolution of Fe3+-containing minerals like goethite and hematite, which are

  18. Insights into the relation between adhesion force and chalcopyrite-bioleaching by Acidithiobacillus ferrooxidans.

    PubMed

    Zhu, Jianyu; Wang, Qianfen; Zhou, Shuang; Li, Qian; Gan, Min; Jiang, Hao; Qin, Wenqing; Liu, Xueduan; Hu, Yuehua; Qiu, Guanzhou

    2015-02-01

    This paper presents a study on the relation between bacterial adhesion force and bioleaching rate of chalcopyrite, which sheds light on the influence of interfacial interaction on bioleaching behavior. In our research, Acidithiobacillus ferrooxidans (A. ferrooxidans) were adapted to grow with FeSO4 · 7H2O, element sulfur or chalcopyrite. Then, surface properties of Acidithiobacillus ferrooxidans and chalcopyrite were analyzed by contact angle, zeta potential and Fourier transform infrared spectroscopy (FTIR). Adhesion force between bacteria and chalcopyrite was measured by atomic force microscopy (AFM). Attachment and bioleaching behaviors were also monitored. The results showed that A. ferrooxidans adapted with chalcopyrite exhibited the strongest adhesion force to chalcopyrite and the highest bioleaching rate. Culture adapted with sulfur bacteria took second place and FeSO4 · 7H2O-adapted bacteria were the lowest. Bioleaching rate and bacterial attachment capacity were positively related to bacterial adhesion force, which is affected by the nature of energy source. According to this work, the attachment of bacteria to chalcopyrite surface is one of the most important aspects that influence the bioleaching process of chalcopyrite.

  19. Type IV pili of Acidithiobacillus ferrooxidans can transfer electrons from extracellular electron donors.

    PubMed

    Li, Yongquan; Li, Hongyu

    2014-03-01

    Studies on Acidithiobacillus ferrooxidans accepting electrons from Fe(II) have previously focused on cytochrome c. However, we have discovered that, besides cytochrome c, type IV pili (Tfp) can transfer electrons. Here, we report conduction by Tfp of A. ferrooxidans analyzed with a conducting-probe atomic force microscope (AFM). The results indicate that the Tfp of A. ferrooxidans are highly conductive. The genome sequence of A. ferrooxidans ATCC 23270 contains two genes, pilV and pilW, which code for pilin domain proteins with the conserved amino acids characteristic of Tfp. Multiple alignment analysis of the PilV and PilW (pilin) proteins indicated that pilV is the adhesin gene while pilW codes for the major protein element of Tfp. The likely function of Tfp is to complete the circuit between the cell surface and Fe(II) oxides. These results indicate that Tfp of A. ferrooxidans might serve as biological nanowires transferring electrons from the surface of Fe(II) oxides to the cell surface.

  20. Inhibitory effect of high concentrations of ferric ions on the activity of Acidithiobacillus ferrooxidans.

    PubMed

    Kawabe, Yoshishige; Inoue, Chihiro; Suto, Koichi; Chida, Tadashi

    2003-01-01

    The influence of high concentrations of ferric ions on the biochemical activity of Acidithiobacillus ferrooxidans was studied using intact cells. The specific oxidation rate of ferrous ions decreased with increasing ferric ion concentration. Lineweaver-Burk plots revealed typical competitive inhibition kinetics, because the slopes varied with the ferric ion concentration. A linear relationship between the slope and the square of the ferric ion concentration revealed that the iron-oxidizing enzyme system of A. ferrooxidans was competitively inhibited by about two molecules of ferric ion. The kinetic equation based on this inhibition model agreed with the experimental observation at a high ferric ion concentration where the bacterium is usually exposed in bioleaching and biooxidation plants.

  1. Engineering the iron-oxidizing chemolithoautotroph Acidithiobacillus ferrooxidans for biochemical production.

    PubMed

    Kernan, Timothy; Majumdar, Sudipta; Li, Xiaozheng; Guan, Jingyang; West, Alan C; Banta, Scott

    2016-01-01

    There is growing interest in developing non-photosynthetic routes for the conversion of CO2 to fuels and chemicals. One underexplored approach is the transfer of energy to the metabolism of genetically modified chemolithoautotrophic bacteria. Acidithiobacillus ferrooxidans is an obligate chemolithoautotroph that derives its metabolic energy from the oxidation of iron or sulfur at low pH. Two heterologous biosynthetic pathways have been expressed in A. ferrooxidans to produce either isobutyric acid or heptadecane from CO2 and the oxidation of Fe(2+). A sevenfold improvement in productivity of isobutyric acid was obtained through improved media formulations in batch cultures. Steady-state efficiencies were lower in continuous cultures, likely due to ferric inhibition. If coupled to solar panels, the photon-to-fuel efficiency of this proof-of-principle process approaches estimates for agriculture-derived biofuels. These efforts lay the foundation for the utilization of this organism in the exploitation of electrical energy for biochemical synthesis.

  2. Use of Walnut Shell Powder to Inhibit Expression of Fe2+-Oxidizing Genes of Acidithiobacillus Ferrooxidans

    PubMed Central

    Li, Yuhui; Liu, Yehao; Tan, Huifang; Zhang, Yifeng; Yue, Mei

    2016-01-01

    Acidithiobacillus ferrooxidans is a Gram-negative bacterium that obtains energy by oxidizing Fe2+ or reduced sulfur compounds. This bacterium contributes to the formation of acid mine drainage (AMD). This study determined whether walnut shell powder inhibits the growth of A. ferrooxidans. First, the effects of walnut shell powder on Fe2+ oxidization and H+ production were evaluated. Second, the chemical constituents of walnut shell were isolated to determine the active ingredient(s). Third, the expression of Fe2+-oxidizing genes and rus operon genes was investigated using real-time polymerase chain reaction. Finally, growth curves were plotted, and a bioleaching experiment was performed to confirm the active ingredient(s) in walnut shells. The results indicated that both walnut shell powder and the phenolic fraction exert high inhibitory effects on Fe2+ oxidation and H+ production by A. ferrooxidans cultured in standard 9K medium. The phenolic components exert their inhibitory effects by down-regulating the expression of Fe2+-oxidizing genes and rus operon genes, which significantly decreased the growth of A. ferrooxidans. This study revealed walnut shell powder to be a promising substance for controlling AMD. PMID:27144574

  3. A dispensable peptide from Acidithiobacillus ferrooxidans tryptophanyl-tRNA synthetase affects tRNA binding.

    PubMed

    Zúñiga, Roberto; Salazar, Juan; Canales, Mauricio; Orellana, Omar

    2002-12-18

    The activation domain of class I aminoacyl-tRNA synthetases, which contains the Rossmann fold and the signature sequences HIGH and KMSKS, is generally split into two halves by the connective peptides (CP1, CP2) whose amino acid sequences are idiosyncratic. CP1 has been shown to participate in the binding of tRNA as well as the editing of the reaction intermediate aminoacyl-AMP or the aminoacyl-tRNA. No function has been assigned to CP2. The amino acid sequence of Acidithiobacillus ferrooxidans TrpRS was predicted from the genome sequence. Protein sequence alignments revealed that A. ferrooxidans TrpRS contains a 70 amino acids long CP2 that is not found in any other bacterial TrpRS. However, a CP2 in the same relative position was found in the predicted sequence of several archaeal TrpRSs. A. ferrooxidans TrpRS is functional in vivo in Escherichia coli. A deletion mutant of A. ferrooxidans trpS lacking the coding region of CP2 was constructed. The in vivo activity of the mutant TrpRS in E. coli, as well as the kinetic parameters of the in vitro activation of tryptophan by ATP, were not altered by the deletion. However, the K(m) value for tRNA was seven-fold higher upon deletion, reducing the efficiency of aminoacylation. Structural modeling suggests that CP2 binds to the inner corner of the L shape of tRNA.

  4. Comparison analysis of coal biodesulfurization and coal's pyrite bioleaching with Acidithiobacillus ferrooxidans.

    PubMed

    Hong, Fen-Fen; He, Huan; Liu, Jin-Yan; Tao, Xiu-Xiang; Zheng, Lei; Zhao, Yi-Dong

    2013-01-01

    Acidithiobacillus ferrooxidans (A. ferrooxidans) was applied in coal biodesulfurization and coal's pyrite bioleaching. The result showed that A. ferrooxidans had significantly promoted the biodesulfurization of coal and bioleaching of coal's pyrite. After 16 days of processing, the total sulfur removal rate of coal was 50.6%, and among them the removal of pyritic sulfur was up to 69.9%. On the contrary, after 12 days of processing, the coal's pyrite bioleaching rate was 72.0%. SEM micrographs showed that the major pyrite forms in coal were massive and veinlets. It seems that the bacteria took priority to remove the massive pyrite. The sulfur relative contents analysis from XANES showed that the elemental sulfur (28.32%) and jarosite (18.99%) were accumulated in the biotreated residual coal. However, XRD and XANES spectra of residual pyrite indicated that the sulfur components were mainly composed of pyrite (49.34%) and elemental sulfur (50.72%) but no other sulfur contents were detected. Based on the present results, we speculated that the pyrite forms in coal might affect sulfur biooxidation process.

  5. Microarray and bioinformatic analyses suggest models for carbon metabolism in the autotroph Acidithiobacillus ferrooxidans

    SciTech Connect

    C. Appia-ayme; R. Quatrini; Y. Denis; F. Denizot; S. Silver; F. Roberto; F. Veloso; J. Valdes; J. P. Cardenas; M. Esparza; O. Orellana; E. Jedlicki; V. Bonnefoy; D. Holmes

    2006-09-01

    Acidithiobacillus ferrooxidans is a chemolithoautotrophic bacterium that uses iron or sulfur as an energy and electron source. Bioinformatic analysis was used to identify putative genes and potential metabolic pathways involved in CO2 fixation, 2P-glycolate detoxification, carboxysome formation and glycogen utilization in At. ferrooxidans. Microarray transcript profiling was carried out to compare the relative expression of the predicted genes of these pathways when the microorganism was grown in the presence of iron versus sulfur. Several gene expression patterns were confirmed by real-time PCR. Genes for each of the above predicted pathways were found to be organized into discrete clusters. Clusters exhibited differential gene expression depending on the presence of iron or sulfur in the medium. Concordance of gene expression within each cluster, suggested that they are operons Most notably, clusters of genes predicted to be involved in CO2 fixation, carboxysome formation, 2P-glycolate detoxification and glycogen biosynthesis were up-regulated in sulfur medium, whereas genes involved in glycogen utilization were preferentially expressed in iron medium. These results can be explained in terms of models of gene regulation that suggest how A. ferrooxidans can adjust its central carbon management to respond to changing environmental conditions.

  6. Differential gene expression in Acidithiobacillus ferrooxidans LR planktonic and attached cells in the presence of chalcopyrite.

    PubMed

    Ossa Henao, Diana Marcela; Vicentini, Renato; Rodrigues, Viviane Drumond; Bevilaqua, Denise; Ottoboni, Laura Maria Mariscal

    2014-07-01

    Acidithiobacillus ferrooxidans is commonly used in bioleaching operations to recover copper from sulfide ores. It is commonly accepted that A. ferrooxidans attaches to mineral surfaces by means of extracellular polymeric substances (EPS), however the role of type IV pili and tight adherence genes in this process is poorly understood. Genes related to the formation of type IV pili and tight adherence were identified in the genome of the bacterium, and in this work, we show that A. ferrooxidans actively expresses these genes, as demonstrated by quantitative real-time PCR analysis using cells incubated with chalcopyrite for 2 h. Significant differences in gene expression were observed between planktonic and adhered cells, with the level of expression being much greater in planktonic cells. These results might indicate that planktonic cells can actively adhere to the substrate. A bioinformatics analysis of interaction networks of the tight adherence and type IV pilus assembly genes revealed a strong relationship between conjugation systems (tra operon) and regulatory systems (PilR, PilS).

  7. Comparison Analysis of Coal Biodesulfurization and Coal's Pyrite Bioleaching with Acidithiobacillus ferrooxidans

    PubMed Central

    Hong, Fen-Fen; He, Huan; Liu, Jin-Yan; Tao, Xiu-Xiang; Zheng, Lei; Zhao, Yi-Dong

    2013-01-01

    Acidithiobacillus ferrooxidans (A. ferrooxidans) was applied in coal biodesulfurization and coal's pyrite bioleaching. The result showed that A. ferrooxidans had significantly promoted the biodesulfurization of coal and bioleaching of coal's pyrite. After 16 days of processing, the total sulfur removal rate of coal was 50.6%, and among them the removal of pyritic sulfur was up to 69.9%. On the contrary, after 12 days of processing, the coal's pyrite bioleaching rate was 72.0%. SEM micrographs showed that the major pyrite forms in coal were massive and veinlets. It seems that the bacteria took priority to remove the massive pyrite. The sulfur relative contents analysis from XANES showed that the elemental sulfur (28.32%) and jarosite (18.99%) were accumulated in the biotreated residual coal. However, XRD and XANES spectra of residual pyrite indicated that the sulfur components were mainly composed of pyrite (49.34%) and elemental sulfur (50.72%) but no other sulfur contents were detected. Based on the present results, we speculated that the pyrite forms in coal might affect sulfur biooxidation process. PMID:24288464

  8. [Dependence of the genotypic characteristics of Acidithiobacillus ferrooxidans on the physical, chemical, and electrophysical properties of pyrites].

    PubMed

    Tupikina, O V; Kondrat'eva, T F; Samorukova, V D; Rassulov, V A; Karavaĭko, G I

    2005-01-01

    Comparison of Acidithiobacillus ferrooxidans strains TFV-1 and TFBk with respect to their capacity to oxidize pyrite 1, with hole-type (p-type) conductivity, or pyrite 2, with an electron-type (n-type) conductivity, showed that, at a pulp density of 1%, both before and after its adaptation to the pyrites, strain TFBk, isolated from a substrate with a more complex mineral composition, grew faster and oxidized the pyrites of both conductivity types more efficiently than strain TFV-1, which was isolated from a mineralogically simple ore. At a pulp density of 3-5%, the oxidation of pyrite 1 by strain TFV-1 and both of the pyrites by strain TFBk began only after an artificial increase in Eh to 600 mV. If the pulp density was increased gradually, strain TFBk could oxidize the pyrites at its higher values than strain TFV-1, with the rate of pyrite 2 oxidation being higher than that of pyrite 1. During chemical oxidation of both of the pyrites, an increase was observed in the absolute values of the coefficients of thermoelectromotive force (KTEMF); during bacterial-chemical oxidation, the KTEMF of pyrite 1 changed insignificantly, whereas the KTEMF of pyrite 2 decreased.

  9. [Dependence of the genotypic characteristics of Acidithiobacillus ferrooxidans on the physical, chemical, and electrophysical properties of pyrites].

    PubMed

    Tupikina, O V; Kondrat'eva, T F; Karavaĭko, G I

    2005-01-01

    This study focused on the effect of physical, chemical, and electrophysical properties of two pyrites, pyrite 1, which had hole-type (p-type) conductivity, and pyrite 2, with electron-type (n-type) conductivity, on the genotypic characteristics of Acidithiobacillus ferrooxidans strains TFV-1 and TFBk, which were isolated from different substrates. After the adaptation of the strains to the pyrites at a pulp density of 1%, pulsed-field electrophoresis revealed changes in the chromosomal DNA of strain TFV-1 adapted to pyrite 1 and strain TFBk adapted to either of the pyrite types. In pyrite-adapted strain TFBk, the plasmid composition was the same as after growth on a medium containing ferrous iron, whereas, in strain TFV-1, changes in plasmid sizes or both in plasmid sizes and plasmid number occurred. After an increase in the density of the pyrite 2 pulp from 1 to 10%, the plasmid number increased from three to four, and, after an increase in the density of the pyrite 1 pulp from 1 to 7%, the plasmid number increased from two to six.

  10. Bioleaching of realgar by Acidithiobacillus ferrooxidans using ferrous iron and elemental sulfur as the sole and mixed energy sources.

    PubMed

    Chen, Peng; Yan, Lei; Leng, Feifan; Nan, Wenbing; Yue, Xiaoxuan; Zheng, Yani; Feng, Na; Li, Hongyu

    2011-02-01

    The characteristics of the bioleaching of realgar by Acidithiobacillus ferrooxidans BY-3 (A. ferrooxidans) were investigated in this work. We examined the effects of using ferrous iron and elemental sulfur as the sole and mixed energy sources on the bioleaching of realgar. Under all experimental conditions, A. ferrooxidans BY-3 significantly enhanced the dissolution of realgar. Moreover, arsenic was more efficiently leached using A. ferrooxidans BY-3 in the presence of ferrous iron than in other culture conditions. A high concentration of arsenic was observed in the absence of alternative energy sources. This concentration was higher than that in cultures with sulfur only and lower than that in cultures with ferrous iron and sulfur. Linear or nonlinear models best fit the experimental data; the nonlinear model exhibited the dual effects of dissolution and removal on the bioleaching of realgar, whereas the linear model only applied to situations of slow bioleaching rather than removal.

  11. Synergistic bioleaching of chalcopyrite and bornite in the presence of Acidithiobacillus ferrooxidans.

    PubMed

    Zhao, Hongbo; Wang, Jun; Hu, Minghao; Qin, Wenqing; Zhang, Yansheng; Qiu, Guanzhou

    2013-12-01

    Bioleaching of chalcopyrite and bornite in the presence of Acidithiobacillus ferrooxidans was carried out to investigate the influences between each other during bioleaching. Bioleaching results indicated that bornite accelerated the dissolution of chalcopyrite, and chalcopyrite also accelerated the dissolution of bornite, it could be described as a synergistic effect during bioleaching, this synergistic effect might be attributed to the galvanic effect between chalcopyrite and bornite, and to the relatively low solution potential as the addition of bornite. Significantly amount of elemental sulfur and jarosite formed on the minerals surface might be the main passivation film inhibiting the further dissolution, and the amount of elemental sulfur significantly increased with the addition of bornite. Results of electrochemical measurements indicated that the oxidation and reduction mechanisms of chalcopyrite and bornite were similar, the addition of bornite or chalcopyrite did not change the oxidative and reductive mechanisms, but increased the oxidation rate.

  12. Bioleaching of heavy metal from woody biochar using Acidithiobacillus ferrooxidans and activation for adsorption.

    PubMed

    Wang, Buyun; Li, Cuiping; Liang, Hui

    2013-10-01

    A woody biochar which was the byproduct of gasification of sawdust was treated with bioleaching by Acidithiobacillus ferrooxidans. After bioleaching, most heavy metal was removed from biochar. Leaching efficiency of heavy metal was efficient in a wide pulp density range from 1% to 10% (w/v) and decreased only a little with the increase in pulp density. It made application of biochar free of heavy metal risk. Benefitting from the improvement in functional group composition and pore structure after bioleaching, adsorption capacity of biochar to methylene blue and heavy metal was enhanced greatly. Adsorption of methylene blue could be described by pseudo-second-order model and Langmuir equation and the enhancement was mainly caused by the modification of physical character of biochar. Adsorption of heavy metal could be described by Freundlich equation and was mainly determined by chemical character of biochar.

  13. Sludge conditioning using biogenic flocculant produced by Acidithiobacillus ferrooxidans for enhancement in dewaterability.

    PubMed

    Kurade, Mayur B; Murugesan, Kumarasamy; Selvam, Ammaiyappan; Yu, Shuk-Man; Wong, Jonathan W C

    2016-10-01

    Biogenic flocculant produced by Acidithiobacillus ferrooxidans was used for sludge conditioning to improve the dewaterability of anaerobically-digested sludge, and its efficiency was compared with commercial cationic polyacrylamide (PAM). Biogenic flocculant rapidly reduced the pH and increased the oxidation-reduction potential of sludge. Capillary suction time (CST) and specific resistant to filtration (SRF) of sludge was decreased by 74% and 89%, respectively, compared with control; and the reductions were 58% CST and 67% SRF higher when compared with commercial polymer. Biogenic treatment improved the sludge calorific value by 13%, and also reduced the unpleasant odor. The small-scale mechanical filter press study showed that the biogenic flocculant can reduce the moisture content of sludge to 70%, and improve the clarity of the filtrate in terms of removal of total suspended solids and total dissolved solids when compared with synthetic polymer treatment.

  14. Bioleaching of zinc and iron from steel plant waste using Acidithiobacillus ferrooxidans.

    PubMed

    Bayat, Oktay; Sever, Efsun; Bayat, Belgin; Arslan, Volkan; Poole, Colin

    2009-01-01

    The bacterial leaching of zinc and iron from solid wastes at the Isdemir iron and steel plant has been investigated using Acidithiobacillus ferrooxidans as the bacterial agent. The effects of a range of operational parameters, including particle size, solids concentration and pH, on the efficiency of the bioleaching process were investigated. In each test, several variables were determined to assess the efficiency of leaching, including slurry pH and redox potential, temperature, bacteria population and concentrations of zinc and iron in solution. Experimental results demonstrated that pulp solids concentration, slurry pH and solids particle size were all important parameters in the bacterial leaching process. Maximum extraction was achieved at pH values around 1.3 and a solids concentration of 1% w/v, with 35% of the Zn content and 37% of the Fe being dissolved.

  15. Study of Acidithiobacillus ferrooxidans and enzymatic bio-Fenton process-mediated corrosion of copper-nickel alloy.

    PubMed

    Jadhav, U; Hocheng, H

    2016-10-01

    This study presents the corrosion behavior of the copper-nickel (Cu-Ni) alloy in the presence of Acidithiobacillus ferrooxidans (A. ferrooxidans) and glucose oxidase (GOx) enzyme. In both the cases ferric ions played an important role in weight loss and thereby to carry out the corrosion of the Cu-Ni alloy. A corrosion rate of 0.6 (±0.008), 2.11 (±0.05), 3.69 (±0.26), 0.7 (±0.006) and 0.08 (±0.002) mm/year was obtained in 72 h using 9K medium with ferrous sulfate, A. ferrooxidans culture supernatant, A. ferrooxidans cells, GOx enzyme and hydrogen peroxide (H2O2) solution respectively. The scanning electron microscopy (SEM) micrographs showed that a variable extent of corrosion was caused by 9K medium with ferrous sulfate, GOx and A. ferrooxidans cells. An arithmetic average surface roughness (Ra) of 174.78 nm was observed for the control work-piece using optical profilometer. The change in Ra was observed with the treatment of the Cu-Ni alloy using various systems. The Ra for 9K medium with ferrous sulfate, GOx and A. ferrooxidans cells was 374.54, 607.32 and 799.48 nm, respectively, after 24 h. These results suggest that A. ferrooxidans cells were responsible for more corrosion of the Cu-Ni alloy than other systems used.

  16. Column bioleaching copper and its kinetics of waste printed circuit boards (WPCBs) by Acidithiobacillus ferrooxidans.

    PubMed

    Chen, Shu; Yang, Yuankun; Liu, Congqiang; Dong, Faqin; Liu, Bijun

    2015-12-01

    Application of bioleaching process for metal recovery from electronic waste has received an increasing attention in recent years. In this work, a column bioleaching of copper from waste printed circuit boards (WPCBs) by Acidithiobacillus ferrooxidans has been investigated. After column bioleaching for 28d, the copper recovery reached at 94.8% from the starting materials contained 24.8% copper. Additionally, the concentration of Fe(3+) concentration varied significantly during bioleaching, which inevitably will influence the Cu oxidation, thus bioleaching process. Thus the variation in Fe(3+) concentration should be taken into consideration in the conventional kinetic models of bioleaching process. Experimental results show that the rate of copper dissolution is controlled by external diffusion rather than internal one because of the iron hydrolysis and formation of jarosite precipitates at the surface of the material. The kinetics of column bioleaching WPCBs remains unchanged because the size and morphology of precipitates are unaffected by maintaining the pH of solution at 2.25 level. In bioleaching process, the formation of jarosite precipitate can be prevented by adding dilute sulfuric acid and maintaining an acidic condition of the leaching medium. In such way, the Fe(2)(+)-Fe(3+) cycle process can kept going and create a favorable condition for Cu bioleaching. Our experimental results show that column Cu bioleaching from WPCBs by A. ferrooxidans is promising.

  17. Immobilization of Acidithiobacillus ferrooxidans on Cotton Gauze for the Bioleaching of Waste Printed Circuit Boards.

    PubMed

    Nie, Hongyan; Zhu, Nengwu; Cao, Yanlan; Xu, Zhiguo; Wu, Pingxiao

    2015-10-01

    The bioleaching parameters of metal concentrates from waste printed circuit boards by Acidithiobacillus ferrooxidans immobilized on cotton gauze in a two-step reactor were investigated in this study. The results indicated that an average ferrous iron oxidation rate of 0.54 g/(L·h) and a ferrous iron oxidation ratio of 96.90 % were obtained after 12 h at aeration rate of 1 L/min in bio-oxidation reactor. After 96 h, the highest leaching efficiency of copper reached 91.68 % under the conditions of the content of the metal powder 12 g/L, the retention time 6 h, and the aeration rate 1 L/min. The bioleaching efficiency of copper could be above 91.12 % under repeated continuous batch operation. Meanwhile, 95.32 % of zinc, 90.32 % of magnesium, 86.31 % of aluminum, and 59.07 % of nickel were extracted after 96 h. All the findings suggested that the recovery of metal concentrates from waste printed circuit boards via immobilization of A. ferrooxidans on cotton gauze was feasible.

  18. α-fur, an antisense RNA gene to fur in the extreme acidophile Acidithiobacillus ferrooxidans.

    PubMed

    Lefimil, C; Jedlicki, E; Holmes, D S

    2014-03-01

    A large non-coding RNA, termed α-Fur, of ~1000 nt has been detected in the extreme acidophile Acidithiobacillus ferrooxidans encoded on the antisense strand to the iron-responsive master regulator fur (ferric uptake regulator) gene. A promoter for α-fur was predicted bioinformatically and validated using gene fusion experiments. The promoter is situated within the coding region and in the same sense as proB, potentially encoding a glutamate 5-kinase. The 3' termination site of the α-fur transcript was determined by 3' rapid amplification of cDNA ends to lie 7 nt downstream of the start of transcription of fur. Thus, α-fur is antisense to the complete coding region of fur, including its predicted ribosome-binding site. The genetic context of α-fur is conserved in several members of the genus Acidithiobacillus but not in all acidophiles, indicating that it is monophyletic but not niche specific. It is hypothesized that α-Fur regulates the cellular level of Fur. This is the fourth example of an antisense RNA to fur, although it is the first in an extreme acidophile, and underscores the growing importance of cis-encoded non-coding RNAs as potential regulators involved in the microbial iron-responsive stimulon.

  19. "Isolation, identification, characterization and polymetallic concentrate leaching studies of tryptic soy- and peptone-resistant thermotolerant Acidithiobacillus ferrooxidans SRDSM2".

    PubMed

    Patel, Mitesh J; Tipre, Devayani R; Dave, Shailesh R

    2011-01-01

    Acidithiobacillus ferrooxidans strain SRDSM2 was isolated from silica containing soil sample collected at a Rajpardi lignite mine. The strain responded to the addition of 0.5 g/L peptone and 1.0 g/L tryptone soya broth in the ferrous sulphate tryptone soya broth (ITSB) medium with 35.3% and 29.6% increase in iron oxidation rate (IOR), but decrease in the IOR at higher peptone or tryptone soya broth levels. The presence of 4 mM of zinc as zinc sulphate in the medium increased the IOR by 24.4%. Forty percent of the inoculated cells survived even after exposure at 80 °C for 120 min and showed 30% ferrous iron oxidation. The Vmax and Ks for iron oxidation by the isolate were 344.82 mg/L/h and 32.25 g/L respectively. The isolate was able to oxidized ferrous iron even in presence of 4.06 M ionic strength of medium and leached>85% copper and zinc from the polymetallic concentrate. Thus, this isolate can be used for bioextraction of metals from polymetallic concentrate.

  20. Cytoplasmic CopZ-Like Protein and Periplasmic Rusticyanin and AcoP Proteins as Possible Copper Resistance Determinants in Acidithiobacillus ferrooxidans ATCC 23270.

    PubMed

    Navarro, Claudio A; von Bernath, Diego; Martínez-Bussenius, Cristóbal; Castillo, Rodrigo A; Jerez, Carlos A

    2015-12-04

    Acidophilic organisms, such as Acidithiobacillus ferrooxidans, possess high-level resistance to copper and other metals. A. ferrooxidans contains canonical copper resistance determinants present in other bacteria, such as CopA ATPases and RND efflux pumps, but these components do not entirely explain its high metal tolerance. The aim of this study was to find other possible copper resistance determinants in this bacterium. Transcriptional expression of A. ferrooxidans genes coding for a cytoplasmic CopZ-like copper-binding chaperone and the periplasmic copper-binding proteins rusticyanin and AcoP, which form part of an iron-oxidizing supercomplex, was found to increase when the microorganism was grown in the presence of copper. All of these proteins conferred more resistance to copper when expressed heterologously in a copper-sensitive Escherichia coli strain. This effect was absent when site-directed-mutation mutants of these proteins with altered copper-binding sites were used in this metal sensitivity assay. These results strongly suggest that the three copper-binding proteins analyzed here are copper resistance determinants in this extremophile and contribute to the high-level metal resistance of this industrially important biomining bacterium.

  1. Enhancing isobutyric acid production from engineered Acidithiobacillus ferrooxidans cells via media optimization.

    PubMed

    Li, Xiaozheng; West, Alan C; Banta, Scott

    2016-04-01

    The chemolithoautotrophic bacterium Acidithiobacillus ferrooxidans has previously been genetically modified to produce isobutyric acid (IBA) from carbon dioxide while obtaining energy from the oxidation of ferrous iron. Here, a combinatorial approach was used to explore the influence of medium composition in both batch and chemostat cultures in order to improve IBA yields (g IBA/mol Fe(2+)) and productivities (g IBA/L/d). Medium pH, ferrous concentration (Fe(2+)), and inclusion of iron chelators all had positive impact on the IBA yield. In batch experiments, gluconate was found to be a superior iron chelator because its use resulted in smaller excursions in pH. In batch cultures, IBA yields decreased linearly with increases in the final effective Fe(3+) concentrations. Chemostat cultures followed similar trends as observed in batch cultures. Specific cellular productivities were found to be a function of the steady state ORP (Oxidation-reduction potential) of the growth medium, which is primarily determined by the Fe(3+) to Fe(2+) ratio. By operating at low ORP, chemostat cultures were able to achieve volumetric productivities as high as 3.8 ± 0.2 mg IBA/L/d which is a 14-fold increase over the previously reported value.

  2. Laboratory chalcopyrite oxidation by Acidithiobacillus ferrooxidans: Oxygen and sulfur isotope fractionation

    USGS Publications Warehouse

    Thurston, R.S.; Mandernack, K.W.; Shanks, Wayne C.

    2010-01-01

    Laboratory experiments were conducted to simulate chalcopyrite oxidation under anaerobic and aerobic conditions in the absence or presence of the bacterium Acidithiobacillus ferrooxidans. Experiments were carried out with 3 different oxygen isotope values of water (??18OH2O) so that approach to equilibrium or steady-state isotope fractionation for different starting conditions could be evaluated. The contribution of dissolved O2 and water-derived oxygen to dissolved sulfate formed by chalcopyrite oxidation was unambiguously resolved during the aerobic experiments. Aerobic oxidation of chalcopyrite showed 93 ?? 1% incorporation of water oxygen into the resulting sulfate during the biological experiments. Anaerobic experiments showed similar percentages of water oxygen incorporation into sulfate, but were more variable. The experiments also allowed determination of sulfate-water oxygen isotope fractionation, ??18OSO4-H2O, of ~ 3.8??? for the anaerobic experiments. Aerobic oxidation produced apparent ??SO4-H2O values (6.4???) higher than the anaerobic experiments, possibly due to additional incorporation of dissolved O2 into sulfate. ??34SSO4 values are ~ 4??? lower than the parent sulfide mineral during anaerobic oxidation of chalcopyrite, with no significant difference between abiotic and biological processes. For the aerobic experiments, a small depletion in ??34SSO4 of ~- 1.5 ?? 0.2??? was observed for the biological experiments. Fewer solids precipitated during oxidation under aerobic conditions than under anaerobic conditions, which may account for the observed differences in sulfur isotope fractionation under these contrasting conditions. ?? 2009 Elsevier B.V.

  3. Selection and evaluation of reference genes for improved interrogation of microbial transcriptomes: case study with the extremophile Acidithiobacillus ferrooxidans

    PubMed Central

    Nieto, Pamela A; Covarrubias, Paulo C; Jedlicki, Eugenia; Holmes, David S; Quatrini, Raquel

    2009-01-01

    Background Normalization is a prerequisite for accurate real time PCR (qPCR) expression analysis and for the validation of microarray profiling data in microbial systems. The choice and use of reference genes that are stably expressed across samples, experimental conditions and designs is a key consideration for the accurate interpretation of gene expression data. Results Here, we evaluate a carefully selected set of reference genes derived from previous microarray-based transcriptional profiling experiments performed on Acidithiobacillus ferrooxidans and identify a set of genes with minimal variability under five different experimental conditions that are frequently used in Acidithiobacilli research. Suitability of these and other previously reported reference genes to monitor the expression of four selected target genes from A. ferrooxidans grown with different energy sources was investigated. Utilization of reference genes map, rpoC, alaS and era results in improved interpretation of gene expression profiles in A. ferrooxidans. Conclusion This investigation provides a validated set of reference genes for studying A. ferrooxidans gene expression under typical biological conditions and an initial point of departure for exploring new experimental setups in this microorganism and eventually in other closely related Acidithiobacilli. The information could also be of value for future transcriptomic experiments in other bacterial systems. PMID:19555508

  4. Catalytic effect of Ag⁺ on arsenic bioleaching from orpiment (As₂S₃) in batch tests with Acidithiobacillus ferrooxidans and Sulfobacillus sibiricus.

    PubMed

    Zhang, Guangji; Chao, Xingwu; Guo, Pei; Cao, Junya; Yang, Chao

    2015-01-01

    Orpiment is one of the major arsenic sulfide minerals which commonly occurs in the gold mine environment and the weathering of this mineral can lead to the contamination of arsenic. In this study, chemical leaching experiments using 10g/L Fe(3+) at 35°C and 50°C were carried out and the results show that orpiment can be leached by Fe(3+) and the leaching rate of orpiment was significantly enhanced in the presence of Ag(+). The bioleaching experiments with mesophilic bacteria Acidithiobacillus ferrooxidans and moderate thermophilic bacteria Sulfobacillus sibiricus were carried out, showing that these two strains can survive in the mineral pulp and oxidize Fe(2+) to regenerate Fe(3+). Based on above results, it is believed that the leaching action of the acidic mining drainage by some bacteria can lead to the release of arsenic from orpiment. Different performances of At. ferrooxidans and S. sibiricus in the tests suggest they follow two different mechanisms and this point of view is further confirmed based on analyses of the composition and morphology of the mineral residue by SEM and EDS.

  5. Comparative proteomic analysis of sulfur-oxidizing Acidithiobacillus ferrooxidans CCM 4253 cultures having lost the ability to couple anaerobic elemental sulfur oxidation with ferric iron reduction.

    PubMed

    Kucera, Jiri; Sedo, Ondrej; Potesil, David; Janiczek, Oldrich; Zdrahal, Zbynek; Mandl, Martin

    2016-09-01

    In extremely acidic environments, ferric iron can be a thermodynamically favorable electron acceptor during elemental sulfur oxidation by some Acidithiobacillus spp. under anoxic conditions. Quantitative 2D-PAGE proteomic analysis of a resting cell suspension of a sulfur-grown Acidithiobacillus ferrooxidans CCM 4253 subculture that had lost its iron-reducing activity revealed 147 protein spots that were downregulated relative to an iron-reducing resting cell suspension of the antecedent sulfur-oxidizing culture and 111 that were upregulated. Tandem mass spectrometric analysis of strongly downregulated spots identified several physiologically important proteins that apparently play roles in ferrous iron oxidation, including the outer membrane cytochrome Cyc2 and rusticyanin. Other strongly repressed proteins were associated with sulfur metabolism, including heterodisulfide reductase, thiosulfate:quinone oxidoreductase and sulfide:quinone reductase. Transcript-level analyses revealed additional downregulation of other respiratory genes. Components of the iron-oxidizing system thus apparently play central roles in anaerobic sulfur oxidation coupled with ferric iron reduction in the studied microbial strain.

  6. Reduction of arsenic content in a complex galena concentrate by Acidithiobacillus ferrooxidans

    PubMed Central

    Makita, Mario; Esperón, Margarita; Pereyra, Benito; López, Alejandro; Orrantia, Erasmo

    2004-01-01

    Background Bioleaching is a process that has been used in the past in mineral pretreatment of refractory sulfides, mainly in the gold, copper and uranium benefit. This technology has been proved to be cheaper, more efficient and environmentally friendly than roasting and high pressure moisture heating processes. So far the most studied microorganism in bioleaching is Acidithiobacillus ferrooxidans. There are a few studies about the benefit of metals of low value through bioleaching. From all of these, there are almost no studies dealing with complex minerals containing arsenopyrite (FeAsS). Reduction and/or elimination of arsenic in these ores increase their value and allows the exploitation of a vast variety of minerals that today are being underexploited. Results Arsenopyrite was totally oxidized. The sum of arsenic remaining in solution and removed by sampling represents from 22 to 33% in weight (yield) of the original content in the mineral. The rest of the biooxidized arsenic form amorphous compounds that precipitate. Galena (PbS) was totally oxidized too, anglesite (PbSO4) formed is virtually insoluble and remains in the solids. The influence of seven factors in a batch process was studied. The maximum rate of arsenic dissolution in the concentrate was found using the following levels of factors: small surface area of particle exposure, low pulp density, injecting air and adding 9 K medium to the system. It was also found that ferric chloride and carbon dioxide decreased the arsenic dissolution rate. Bioleaching kinetic data of arsenic solubilization were used to estimate the dilution rate for a continuous culture. Calculated dilution rates were relatively small (0.088–0.103 day-1). Conclusion Proper conditions of solubilization of arsenic during bioleaching are key features to improve the percentage (22 to 33% in weight) of arsenic removal. Further studies are needed to determine other factors that influence specifically the solubilization of arsenic in

  7. Attachment of Acidithiobacillus ferrooxidans and Leptospirillum ferriphilum cultured under varying conditions to pyrite, chalcopyrite, low-grade ore and quartz in a packed column reactor.

    PubMed

    Africa, Cindy-Jade; van Hille, Robert P; Harrison, Susan T L

    2013-02-01

    The attachment of Acidithiobacillus ferrooxidans and Leptospirillum ferriphilum spp. grown on ferrous medium or adapted to a pyrite mineral concentrate to four mineral substrata, namely, chalcopyrite and pyrite concentrates, a low-grade chalcopyrite ore (0.5 wt%) and quartzite, was investigated. The quartzite represented a typical gangue mineral and served as a control. The attachment studies were carried out in a novel particle-coated column reactor. The saturated reactor containing glass beads, which were coated with fine mineral concentrates, provided a quantifiable surface area of mineral concentrate and maintained good fluid flow. A. ferrooxidans and Leptospirillum spp. had similar attachment characteristics. Enhanced attachment efficiency occurred with bacteria grown on sulphide minerals relative to those grown on ferrous sulphate in an ore-free environment. Selective attachment to sulphide minerals relative to gangue materials occurred, with mineral adapted cultures attaching to the minerals more efficiently than ferrous grown cultures. Mineral-adapted cultures showed highest levels of attachment to pyrite (74% and 79% attachment for A. ferrooxidans and L. ferriphilum, respectively). This was followed by attachment of mineral-adapted cultures to chalcopyrite (63% and 58% for A. ferrooxidans and L. ferriphilum, respectively). A. ferrooxidans and L. ferriphilum exhibited lower levels of attachment to low-grade ore and quartz relative to the sulphide minerals.

  8. A direct observation of bacterial coverage and biofilm formation by Acidithiobacillus ferrooxidans on chalcopyrite and pyrite surfaces.

    PubMed

    Yang, Y; Tan, S N; Glenn, A M; Harmer, S; Bhargava, S; Chen, M

    2015-01-01

    To obtain a fundamental understanding of the population behaviour of Acidithiobacillus ferrooxidans at chalcopyrite and pyrite surfaces, the early stage attachment behaviour and biofilm formation by this bacterium on chalcopyrite (CuFeS2) and pyrite (FeS2) were studied by optical microscopy, Raman spectroscopy, time-of-flight secondary ion mass spectrometry (ToF-SIMS) and electron backscatter diffraction (EBSD). The results indicate there was no significant difference in selectivity of bacterial attachment between chalcopyrite and pyrite. However, the result of ToF-SIMS analysis suggests that the surface of the pyrite was covered more extensively by biofilm than that of the chalcopyrite, which may indicate more extracellular polymeric substances (EPS) formation by bacterial cells growing on pyrite. EBSD and optical image analysis indicated that selectivity of bacterial attachment to chalcopyrite was not significantly affected by crystal orientation. The results also suggest that the bacterial population in defective areas of chalcopyrite was significantly higher than on the polished surfaces.

  9. Effects of pyrite bioleaching solution of Acidithiobacillus ferrooxidans on viability, differentiation and mineralization potentials of rat osteoblasts.

    PubMed

    Zhou, Jian; Chen, Ke-Ming; Zhi, De-Juan; Xie, Qin-Jian; Xian, Cory J; Li, Hong-Yu

    2015-12-01

    Iron pyrite, an important component of traditional Chinese medicine, has a poor solubility, bioavailability, and patient compliance due to a high dose required and associated side effects, all of which have limited its clinical applications and experimental studies on its action mechanisms in improving fracture healing. This study investigated Acidithiobacillus ferrooxidans (A.f)-bioleaching of two kinds of pyrites and examined bioactivities of the derived solutions in viability and osteogenic differentiation in rat calvarial osteoblasts. A.f bioleaching improved element contents (Fe, Mn, Zn, Cu, and Se) in the derived solutions and the solutions concentration-dependently affected osteoblast viability and differentiation. While the solutions had no effects at low concentrations and inhibited the osteoblast alkaline phosphatase (ALP) activity at high concentrations, they improved ALP activity at their optimal concentrations. The improved osteoblast differentiation and osteogenic function at optimal concentrations were also revealed by levels of ALP cytochemical staining, calcium deposition, numbers and areas of mineralized nodules formed, mRNA and protein expression levels of osteogenesis-related genes (osteocalcin, Bmp-2, Runx-2, and IGF-1), and Runx-2 nuclear translocation. Data from this study will be useful in offering new strategies for improving pyrite bioavailability and providing a mechanistic explanation for the beneficial effects of pyrite in improving bone healing.

  10. Synchrotron radiation based STXM analysis and micro-XRF mapping of differential expression of extracellular thiol groups by Acidithiobacillus ferrooxidans grown on Fe(2+) and S(0).

    PubMed

    Xia, Jin-Lan; Liu, Hong-Chang; Nie, Zhen-Yuan; Peng, An-An; Zhen, Xiang-Jun; Yang, Yun; Zhang, Xiu-Li

    2013-09-01

    The differential expression of extracellular thiol groups by Acidithiobacillus ferrooxidans grown on substrates Fe(2+) and S(0) was investigated by using synchrotron radiation based scanning transmission X-ray microscopy (STXM) imaging and microbeam X-ray fluorescence (μ-XRF) mapping. The extracellular thiol groups (SH) were first alkylated by iodoacetic acid forming Protein-SCH2COOH and then the P-SCH2COOH was marked by calcium ions forming P-SCH2COOCa. The STXM imaging and μ-XRF mapping of SH were based on analysis of SCH2COO-bonded Ca(2+). The results indicated that the thiol group content of A. ferrooxidans grown on S(0) is 3.88 times to that on Fe(2+). Combined with selective labeling of SH by Ca(2+), the STXM imaging and μ-XRF mapping provided an in situ and rapid analysis of differential expression of extracellular thiol groups.

  11. Quantitative X-ray photoelectron spectroscopy-based depth profiling of bioleached arsenopyrite surface by Acidithiobacillus ferrooxidans

    NASA Astrophysics Data System (ADS)

    Zhu, Tingting; Lu, Xiancai; Liu, Huan; Li, Juan; Zhu, Xiangyu; Lu, Jianjun; Wang, Rucheng

    2014-02-01

    In supergene environments, microbial activities significantly enhance sulfide oxidation and result in the release of heavy metals, causing serious contamination of soils and waters. As the most commonly encountered arsenic mineral in nature, arsenopyrite (FeAsS) accounts for arsenic contaminants in various environments. In order to investigate the geochemical behavior of arsenic during microbial oxidation of arsenopyrite, (2 3 0) surfaces of arsenopyrite slices were characterized after acidic (pH 2.00) and oxidative decomposition with or without an acidophilic microorganism Acidithiobacillus ferrooxidans. The morphology as well as chemical and elemental depth profiles of the oxidized arsenopyrite surface were investigated by scanning electron microscopy and X-ray photoelectron spectroscopy. With the mediation of bacteria, cell-shaped and acicular pits were observed on the reacted arsenopyrite surface, and the concentration of released arsenic species in solution was 50 times as high as that of the abiotic reaction after 10 days reaction. Fine-scale XPS depth profiles of the reacted arsenopyrite surfaces after both microbial and abiotic oxidation provided insights into the changes in chemical states of the elements in arsenopyrite surface layers. Within the 450 nm surface layer of abiotically oxidized arsenopyrite, Fe(III)-oxides appeared and gradually increased towards the surface, and detectable sulfite and monovalent arsenic appeared above 50 nm. In comparison, higher contents of ferric sulfate, sulfite, and arsenite were found in the surface layer of approximately 3 μm of the microbially oxidized arsenopyrite. Intermediates, such as Fe(III)-AsS and S0, were detectable in the presence of bacteria. Changes of oxidative species derived from XPS depth profiles show the oxidation sequence is Fe > As = S in abiotic oxidation, and Fe > S > As in microbial oxidation. Based on these results, a possible reaction path of microbial oxidation was proposed in a concept model.

  12. Insights into the Quorum Sensing Regulon of the Acidophilic Acidithiobacillus ferrooxidans Revealed by Transcriptomic in the Presence of an Acyl Homoserine Lactone Superagonist Analog.

    PubMed

    Mamani, Sigde; Moinier, Danielle; Denis, Yann; Soulère, Laurent; Queneau, Yves; Talla, Emmanuel; Bonnefoy, Violaine; Guiliani, Nicolas

    2016-01-01

    While a functional quorum sensing system has been identified in the acidophilic chemolithoautotrophic Acidithiobacillus ferrooxidans ATCC 23270(T) and shown to modulate cell adhesion to solid substrates, nothing is known about the genes it regulates. To address the question of how quorum sensing controls biofilm formation in A. ferrooxidans (T), the transcriptome of this organism in conditions in which quorum sensing response is stimulated by a synthetic superagonist AHL (N-acyl homoserine lactones) analog has been studied. First, the effect on biofilm formation of a synthetic AHL tetrazolic analog, tetrazole 9c, known for its agonistic QS activity, was assessed by fluorescence and electron microscopy. A fast adherence of A. ferrooxidans (T) cells on sulfur coupons was observed. Then, tetrazole 9c was used in DNA microarray experiments that allowed the identification of genes regulated by quorum sensing signaling, and more particularly, those involved in early biofilm formation. Interestingly, afeI gene, encoding the AHL synthase, but not the A. ferrooxidans quorum sensing transcriptional regulator AfeR encoding gene, was shown to be regulated by quorum sensing. Data indicated that quorum sensing network represents at least 4.5% (141 genes) of the ATCC 23270(T) genome of which 42.5% (60 genes) are related to biofilm formation. Finally, AfeR was shown to bind specifically to the regulatory region of the afeI gene at the level of the palindromic sequence predicted to be the AfeR binding site. Our results give new insights on the response of A. ferrooxidans to quorum sensing and on biofilm biogenesis.

  13. Insights into the Quorum Sensing Regulon of the Acidophilic Acidithiobacillus ferrooxidans Revealed by Transcriptomic in the Presence of an Acyl Homoserine Lactone Superagonist Analog

    PubMed Central

    Mamani, Sigde; Moinier, Danielle; Denis, Yann; Soulère, Laurent; Queneau, Yves; Talla, Emmanuel; Bonnefoy, Violaine; Guiliani, Nicolas

    2016-01-01

    While a functional quorum sensing system has been identified in the acidophilic chemolithoautotrophic Acidithiobacillus ferrooxidans ATCC 23270T and shown to modulate cell adhesion to solid substrates, nothing is known about the genes it regulates. To address the question of how quorum sensing controls biofilm formation in A. ferrooxidansT, the transcriptome of this organism in conditions in which quorum sensing response is stimulated by a synthetic superagonist AHL (N-acyl homoserine lactones) analog has been studied. First, the effect on biofilm formation of a synthetic AHL tetrazolic analog, tetrazole 9c, known for its agonistic QS activity, was assessed by fluorescence and electron microscopy. A fast adherence of A. ferrooxidansT cells on sulfur coupons was observed. Then, tetrazole 9c was used in DNA microarray experiments that allowed the identification of genes regulated by quorum sensing signaling, and more particularly, those involved in early biofilm formation. Interestingly, afeI gene, encoding the AHL synthase, but not the A. ferrooxidans quorum sensing transcriptional regulator AfeR encoding gene, was shown to be regulated by quorum sensing. Data indicated that quorum sensing network represents at least 4.5% (141 genes) of the ATCC 23270T genome of which 42.5% (60 genes) are related to biofilm formation. Finally, AfeR was shown to bind specifically to the regulatory region of the afeI gene at the level of the palindromic sequence predicted to be the AfeR binding site. Our results give new insights on the response of A. ferrooxidans to quorum sensing and on biofilm biogenesis. PMID:27683573

  14. AHL signaling molecules with a large acyl chain enhance biofilm formation on sulfur and metal sulfides by the bioleaching bacterium Acidithiobacillus ferrooxidans.

    PubMed

    González, Alex; Bellenberg, Sören; Mamani, Sigde; Ruiz, Lina; Echeverría, Alex; Soulère, Laurent; Doutheau, Alain; Demergasso, Cecilia; Sand, Wolfgang; Queneau, Yves; Vera, Mario; Guiliani, Nicolas

    2013-04-01

    Biofilm formation plays a pivotal role in bioleaching activities of bacteria in both industrial and natural environments. Here, by visualizing attached bacterial cells on energetic substrates with different microscopy techniques, we obtained the first direct evidence that it is possible to positively modulate biofilm formation of the extremophilic bacterium Acidithiobacillus ferrooxidans on sulfur and pyrite surfaces by using Quorum Sensing molecules of the N-acylhomoserine lactone type (AHLs). Our results revealed that AHL-signaling molecules with a long acyl chain (12 or 14 carbons) increased the adhesion of A. ferrooxidans cells to these substrates. In addition, Card-Fish experiments demonstrated that C14-AHL improved the adhesion of indigenous A. ferrooxidans cells from a mixed bioleaching community to pyrite. Finally, we demonstrated that this improvement of cell adhesion is correlated with an increased production of extracellular polymeric substances. Our results open up a promising means to develop new strategies for the improvement of bioleaching efficiency and metal recovery, which could also be used to control environmental damage caused by acid mine/rock drainage.

  15. Addition of citrate to Acidithiobacillus ferrooxidans cultures enables precipitate-free growth at elevated pH and reduces ferric inhibition.

    PubMed

    Li, Xiaozheng; Mercado, Roel; Kernan, Timothy; West, Alan C; Banta, Scott

    2014-10-01

    Acidithiobacillus ferrooxidans is an acidophilic chemolithoautotroph that is important in biomining and other biotechnological operations. The cells are able to oxidize inorganic iron, but the insolubility and product inhibition by Fe(3+) complicates characterization of these cultures. Here we explore the growth kinetics of A. ferrooxidans in iron-based medium in a pH range from 1.6 to 2.2. It was found that as the pH was increased from 1.6 to 2.0, the maintenance coefficient decreased while both the growth kinetics and maximum cell yield increased in the precipitate-free, low Fe(2+) concentration medium. In higher iron media a similar trend was observed at low pH, but the formation of precipitates at higher pH (2.0) hampered cell growth and lowered the specific growth rate and maximum cell yield. In order to eliminate ferric precipitates, chelating agents were introduced into the medium. Citric acid was found to be relatively non-toxic and did not appear to interfere with iron oxidation at a maximum concentration of 70 mM. Inclusion of citric acid prevented precipitation and A. ferrooxidans growth parameters resumed their trends as a function of pH. The addition of citrate also decreased the apparent substrate saturation constant (KS ) indicating a reduction in the competitive inhibition of growth by ferric ions. These results indicate that continuous cultures of A. ferrooxidans in the presence of citrate at elevated pH will enable enhanced cell yields and productivities. This will be critical as these cells are used in the development of new biotechnological applications such as electrofuel production.

  16. Influence of chloride and sulfate on formation of akaganéite and schwertmannite through ferrous biooxidation by Acidithiobacillus ferrooxidans cells.

    PubMed

    Xiong, Huixin; Liao, Yuehua; Zhou, Lixiang

    2008-12-01

    Iron (oxyhydr)oxides play important roles in the fixation of toxic elements and also in the distribution of nutrients for plants in soils. Akaganéite and schwertmannite, as the iron oxyhydroxides having an analogous tunnel structure, have been widely recognized in Fe-rich environments. The objective of this study was to examine the formation of akaganéite/ schwertmannite via biooxidation of 0.1 M of ferrous solution containing only Cl-, SO4(2-) or both the anions with a Cl-/SO4(2-) mole ratio of 1, 3, 6, and 10 by chloride-acclimated Acidithiobacillus ferrooxidans cells. Results showed that ferrous iron in chloride/sulfate-containing solutions could be easily biooxidized to ferric iron, and subsequent Fe(III)-hydrolysis/precipitation could result in the formation of large quantity of akaganéite/schwertmannite precipitates. The resulting precipitates were identified to be the pure akaganéite (Fe8O8(OH)7.1(Cl)0.9, the pure schwertmannite (Fe8O8(OH)4.42(SO4)1.79, and the main schwertmannite phase (Fe8O8(OH)(8-2x)(SO4)x, with 1.09 < or = x < or = 1.73), respectively, under different Cl-/SO4(2-) mole ratio conditions. Obviously, sulfate inhibited drastically the bioformation of akaganéite but facilitated schwertmannite phase occurrence in the ferrous solution containing both sulfate and chloride. However, the presence of chloride ion in initial ferrous solution containing sulfate and Acidithiobacillus ferrooxidans cells would affect the morphology and other characteristics of schwertmannite generated.

  17. Expression and activity of the Calvin-Benson-Bassham cycle transcriptional regulator CbbR from Acidithiobacillus ferrooxidans in Ralstonia eutropha.

    PubMed

    Esparza, Mario; Jedlicki, Eugenia; Dopson, Mark; Holmes, David S

    2015-08-01

    Autotrophic fixation of carbon dioxide into cellular carbon occurs via several pathways but quantitatively, the Calvin-Benson-Bassham cycle is the most important. CbbR regulates the expression of the cbb genes involved in CO2 fixation via the Calvin-Benson-Bassham cycle in a number of autotrophic bacteria. A gene potentially encoding CbbR (cbbR(AF)) has been predicted in the genome of the chemolithoautotrophic, extreme acidophile Acidithiobacillus ferrooxidans. However, this microorganism is recalcitrant to genetic manipulation impeding the experimental validation of bioinformatic predictions. Two novel functional assays were devised to advance our understanding of cbbR(AF) function using the mutated facultative autotroph Ralstonia eutropha H14 ΔcbbR as a surrogate host to test gene function: (i) cbbR(AF) was expressed in R. eutropha and was able to complement ΔcbbR; and (ii) CbbR(AF) was able to regulate the in vivo activity of four A. ferrooxidans cbb operon promoters in R. eutropha. These results open up the use of R. eutropha as a surrogate host to explore cbbR(AF) activity.

  18. Complete genome sequence of Acidimicrobium ferrooxidans type strain (ICPT)

    SciTech Connect

    Clum, Alicia; Nolan, Matt; Lang, Elke; Glavina Del Rio, Tijana; Tice, Hope; Copeland, Alex; Cheng, Jan-Fang; Lucas, Susan; Chen, Feng; Bruce, David; Goodwin, Lynne; Pitluck, Sam; Ivanova, Natalia; Mavrommatis, Konstantinos; Mikhailova, Natalia; Pati, Amrita; Chen, Amy; Palaniappan, Krishna; Goker, Markus; Spring, Stefan; Land, Miriam; Hauser, Loren; Chang, Yun-Juan; Jefferies, Cynthia C.; Chain, Patrick; Bristow, James; Eisen, Jonathan A.; Markowitz, Victor; Hugenholtz, Philip; Kyrpides, Nikos C.; Klenk, Hans-Peter; Lapidus, Alla

    2009-05-20

    Acidimicrobium ferrooxidans (Clark and Norris 1996) is the sole and type species of the genus, which until recently was the only genus within the actinobacterial family Acidimicrobiaceae and in the order Acidomicrobiales. Rapid oxidation of iron pyrite during autotrophic growth in the absence of an enhanced CO2 concentration is characteristic for A. ferrooxidans. Here we describe the features of this organism, together with the complete genome sequence, and annotation. This is the first complete genome sequence of the order Acidomicrobiales, and the 2,158,157 bp long single replicon genome with its 2038 protein coding and 54 RNA genes is part of the Genomic Encyclopedia of Bacteria and Archaea project.

  19. Effect of calcium oxide on the efficiency of ferrous ion oxidation and total iron precipitation during ferrous ion oxidation in simulated acid mine drainage treatment with inoculation of Acidithiobacillus ferrooxidans.

    PubMed

    Liu, Fenwu; Zhou, Jun; Jin, Tongjun; Zhang, Shasha; Liu, Lanlan

    2016-01-01

    Calcium oxide was added into ferrous ion oxidation system in the presence of Acidithiobacillus ferrooxidans at concentrations of 0-4.00 g/L. The pH, ferrous ion oxidation efficiency, total iron precipitation efficiency, and phase of the solid minerals harvested from different treatments were investigated during the ferrous ion oxidation process. In control check (CK) system, pH of the solution decreased from 2.81 to 2.25 when ferrous ions achieved complete oxidation after 72 h of Acidithiobacillus ferrooxidans incubation without the addition of calcium oxide, and total iron precipitation efficiency reached 20.2%. Efficiency of ferrous ion oxidation and total iron precipitation was significantly improved when the amount of calcium oxide added was ≤1.33 g/L, and the minerals harvested from systems were mainly a mixture of jarosite and schwertmannite. For example, the ferrous ion oxidation efficiency reached 100% at 60 h and total iron precipitation efficiency was increased to 32.1% at 72 h when 1.33 g/L of calcium oxide was added. However, ferrous ion oxidation and total iron precipitation for jarosite and schwertmannite formation were inhibited if the amount of calcium oxide added was above 2.67 g/L, and large amounts of calcium sulfate dihydrate were generated in systems.

  20. Community dynamics of attached and free cells and the effects of attached cells on chalcopyrite bioleaching by Acidithiobacillus sp.

    PubMed

    Yang, Hailin; Feng, Shoushuai; Xin, Yu; Wang, Wu

    2014-02-01

    The community dynamics of attached and free cells of Acidithiobacillus sp. were investigated and compared during chalcopyrite bioleaching process. In the mixed strains system, Acidithiobacillus ferrooxidans was the dominant species at the early stage while Acidithiobacillus thiooxidans owned competitive advantage from the middle stage to the end of bioprocess. Meanwhile, compared to A. ferrooxidans, more significant effects of attached cells on free biomass with A. thiooxidans were shown in either the pure or mixed strains systems. Moreover, the effects of attached cells on key chemical parameters were also studied in different adsorption-deficient systems. Consistently, the greatest reduction of key chemical ion was shown with A. thiooxidans and the loss of bioleaching efficiency was high to 50.5%. These results all demonstrated the bioleaching function of attached cells was more efficient than the free cells, especially with A. thiooxidans. These notable results would help us to further understand the chalcopyrite bioleaching.

  1. Cross-comparison of leaching strains isolated from two different regions: Chambishi and Dexing copper mines.

    PubMed

    Ngom, Baba; Liang, Yili; Liu, Xueduan

    2014-01-01

    A cross-comparison of six strains isolated from two different regions, Chambishi copper mine (Zambia, Africa) and Dexing copper mine (China, Asia), was conducted to study the leaching efficiency of low grade copper ores. The strains belong to the three major species often encountered in bioleaching of copper sulfide ores under mesophilic conditions: Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, and Leptospirillum ferriphilum. Prior to their study in bioleaching, the different strains were characterized and compared at physiological level. The results revealed that, except for copper tolerance, strains within species presented almost similar physiological traits with slight advantages of Chambishi strains. However, in terms of leaching efficiency, native strains always achieved higher cell density and greater iron and copper extraction rates than the foreign microorganisms. In addition, microbial community analysis revealed that the different mixed cultures shared almost the same profile, and At. ferrooxidans strains always outcompeted the other strains.

  2. Cross-Comparison of Leaching Strains Isolated from Two Different Regions: Chambishi and Dexing Copper Mines

    PubMed Central

    Ngom, Baba; Liang, Yili; Liu, Xueduan

    2014-01-01

    A cross-comparison of six strains isolated from two different regions, Chambishi copper mine (Zambia, Africa) and Dexing copper mine (China, Asia), was conducted to study the leaching efficiency of low grade copper ores. The strains belong to the three major species often encountered in bioleaching of copper sulfide ores under mesophilic conditions: Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, and Leptospirillum ferriphilum. Prior to their study in bioleaching, the different strains were characterized and compared at physiological level. The results revealed that, except for copper tolerance, strains within species presented almost similar physiological traits with slight advantages of Chambishi strains. However, in terms of leaching efficiency, native strains always achieved higher cell density and greater iron and copper extraction rates than the foreign microorganisms. In addition, microbial community analysis revealed that the different mixed cultures shared almost the same profile, and At. ferrooxidans strains always outcompeted the other strains. PMID:25478575

  3. Manipulation of pyrite colonization and leaching by iron-oxidizing Acidithiobacillus species.

    PubMed

    Bellenberg, Sören; Barthen, Robert; Boretska, Mariia; Zhang, Ruiyong; Sand, Wolfgang; Vera, Mario

    2015-02-01

    In this study, the process of pyrite colonization and leaching by three iron-oxidizing Acidithiobacillus species was investigated by fluorescence microscopy, bacterial attachment, and leaching assays. Within the first 4-5 days, only the biofilm subpopulation was responsible for pyrite dissolution. Pyrite-grown cells, in contrast to iron-grown cells, were able to oxidize iron(II) ions or pyrite after 24 h iron starvation and incubation with 1 mM H₂O₂, indicating that these cells were adapted to the presence of enhanced levels of reactive oxygen species (ROS), which are generated on metal sulfide surfaces. Acidithiobacillus ferrivorans SS3 and Acidithiobacillus ferrooxidans R1 showed enhanced pyrite colonization and biofilm formation compared to A. ferrooxidans (T). A broad range of factors influencing the biofilm formation on pyrite were also identified, some of them were strain-specific. Cultivation at non-optimum growth temperatures or increased ionic strength led to a decreased colonization of pyrite. The presence of iron(III) ions increased pyrite colonization, especially when pyrite-grown cells were used, while the addition of 20 mM copper(II) ions resulted in reduced biofilm formation on pyrite. This observation correlated with a different extracellular polymeric substance (EPS) composition of copper-exposed cells. Interestingly, the addition of 1 mM sodium glucuronate in combination with iron(III) ions led to a 5-fold and 7-fold increased cell attachment after 1 and 8 days of incubation, respectively, in A. ferrooxidans (T). In addition, sodium glucuronate addition enhanced pyrite dissolution by 25%.

  4. Detection, identification and typing of Acidithiobacillus species and strains: a review.

    PubMed

    Nuñez, Harold; Covarrubias, Paulo C; Moya-Beltrán, Ana; Issotta, Francisco; Atavales, Joaquín; Acuña, Lillian G; Johnson, D Barrie; Quatrini, Raquel

    2016-09-01

    The genus Acidithiobacillus comprises several species of Gram-negative acidophilic bacteria that thrive in natural and man-made low pH environments in a variety of geo-climatic contexts. Beyond their fundamental interest as model extreme acidophiles, these bacteria are involved in the processing of minerals and the desulfurization of coal and natural gas, and are also sources of environmental pollution due to their generation of acid mine drainage and corrosion of cement and concrete structures. Acidithiobacillus spp. are therefore considered a biotechnologically relevant group of bacteria, and their identification and screening in natural and industrial environments is of great concern. Several molecular typing methodologies have been instrumental in improving knowledge of the inherent diversity of acidithiobacilli by providing information on the genetic subtypes sampled in public and private culture collections; more recently, they have provided specific insight into the diversity of acidithiobacilli present in industrial and natural environments. The aim of this review is to provide an overview of techniques used in molecular detection, identification and typing of Acidithiobacillus spp. These methods will be discussed in the context of their contribution to the general and specific understanding of the role of the acidithiobacilli in microbial ecology and industrial biotechnology. Emerging opportunities for industrial and environmental surveillance of acidithiobacilli using next-generation molecular typing methodologies are also reviewed.

  5. Chlorobium ferrooxidans sp. nov., a phototrophic green sulfur bacterium that oxidizes ferrous iron in coculture with a "Geospirillum" sp. strain.

    PubMed

    Heising, S; Richter, L; Ludwig, W; Schink, B

    1999-08-01

    A green phototrophic bacterium was enriched with ferrous iron as sole electron donor and was isolated in defined coculture with a spirilloid chemoheterotrophic bacterium. The coculture oxidized ferrous iron to ferric iron with stoichiometric formation of cell mass from carbon dioxide. Sulfide, thiosulfate, or elemental sulfur was not used as electron donor in the light. Hydrogen or acetate in the presence of ferrous iron increased the cell yield of the phototrophic partner, and hydrogen could also be used as sole electron source. Complexed ferric iron was slowly reduced to ferrous iron in the dark, with hydrogen as electron source. Similar to Chlorobium limicola, the phototrophic bacterium contained bacteriochlorophyll c and chlorobactene as photosynthetic pigments, and also resembled representatives of this species morphologically. On the basis of 16S rRNA sequence comparisons, this organism clusters with Chlorobium, Prosthecochloris, and Pelodictyon species within the green sulfur bacteria phylum. Since the phototrophic partner in the coculture KoFox is only moderately related to the other members of the cluster, it is proposed as a new species, Chlorobium ferrooxidans. The chemoheterotrophic partner bacterium, strain KoFum, was isolated in pure culture with fumarate as sole substrate. The strain was identified as a member of the epsilon-subclass of the Proteobacteria closely related to "Geospirillum arsenophilum" on the basis of physiological properties and 16S rRNA sequence comparison. The "Geospirillum" strain was present in the coculture only in low numbers. It fermented fumarate, aspartate, malate, or pyruvate to acetate, succinate, and carbon dioxide, and could reduce nitrate to dinitrogen gas. It was not involved in ferrous iron oxidation but possibly provided a thus far unidentified growth factor to the phototrophic partner.

  6. Molecular genetics of Thiobacillus ferrooxidans.

    PubMed Central

    Rawlings, D E; Kusano, T

    1994-01-01

    Thiobacillus ferrooxidans is a gram-negative, highly acidophilic (pH 1.5 to 2.0), autotrophic bacterium that obtains its energy through the oxidation of ferrous iron or reduced inorganic sulfur compounds. It is usually dominant in the mixed bacterial populations that are used industrially for the extraction of metals such as copper and uranium from their ores. More recently, these bacterial consortia have been used for the biooxidation of refractory gold-bearing arsenopyrite ores prior to the recovery of gold by cyanidation. The commercial use of T. ferrooxidans has led to an increasing interest in the genetics and molecular biology of the bacterium. Initial investigations were aimed at determining whether the unique physiology and specialized habitat of T. ferrooxidans had been accompanied by a high degree of genetic drift from other gram-negative bacteria. Early genetic studies were comparative in nature and concerned the isolation of genes such as nifHDK, glnA, and recA, which are widespread among bacteria. From a molecular biology viewpoint, T. ferrooxidans appears to be a typical member of the proteobacteria. In most instances, cloned gene promoters and protein products have been functional in Escherichia coli. Although T. ferrooxidans has proved difficult to transform with DNA, research on indigenous plasmids and the isolation of the T. ferrooxidans merA gene have resulted in the development of a low-efficiency electroporation system for one strain of T. ferrooxidans. The most recent studies have focused on the molecular genetics of the pathways associated with nitrogen metabolism, carbon dioxide fixation, and components of the energy-producing mechanisms. PMID:8177170

  7. Physiological and comparative genomic analysis of Acidithiobacillus ferrivorans PQ33 provides psychrotolerant fitness evidence for oxidation at low temperature.

    PubMed

    Ccorahua-Santo, Robert; Eca, Anika; Abanto, Michel; Guerra, Gregory; Ramírez, Pablo

    2017-02-21

    Friendly environmental hydrometallurgy at low temperatures is principally promoted by Acidithiobacillus ferrivorans. Until recently, the synergy between cold tolerance and the molecular mechanism of ferrous iron (Fe(2+)) oxidation was unknown. In the present paper, we conducted a physiological and comparative genomics analysis of the new strain A. ferrivorans PQ33 to elucidate the oxidation mechanism at low temperatures, with emphasis placed on trehalose and the Rus operon. PQ33 exhibited a doubling time of 66.6 h in Fe(2+) at pH 1.6 and 63.6 h in CuS at 5 °C. Genomic island (GI) identification and comparative genome analysis were performed with four available genomes of Acidithiobacillus sp. The genome comprised 3,298,172 bp and 56.55% GC content. In contrast to ATCC Acidithiobacillus ferrooxidans strains, the genome of A. ferrivorans PQ33 harbors one GI, which contains a RusB gene. Moreover, five genes of peptidyl-prolyl cis-trans isomerase (PPIases) were observed. Furthermore, comparative analysis of the trehalose operon suggested the presence of a horizontal transfer event. In addition, comparison of rusticyanin proteins revealed that RusB has better intrinsic flexibility than RusA. This comparison suggests psychrotolerant fitness and supports the genetic canalization of A. ferrivorans PQ33 for oxidation at low temperature.

  8. Isolation and characterization of a novel Acidithiobacillus ferrivorans strain from the Chilean Altiplano: attachment and biofilm formation on pyrite at low temperature.

    PubMed

    Barahona, Sergio; Dorador, Cristina; Zhang, Ruiyong; Aguilar, Pablo; Sand, Wolfgang; Vera, Mario; Remonsellez, Francisco

    2014-11-01

    Microorganisms are used to aid the extraction of valuable metals from low-grade sulfide ores in mines worldwide, but relatively little is known about this process in cold environments. This study comprises a preliminary analysis of the bacterial diversity of the polyextremophilic acid River Aroma located in the Chilean Altiplano, and revealed that Betaproteobacteria was the most dominant bacterial group (Gallionella-like and Thiobacillus-like). Taxa characteristic of leaching environments, such Acidithiobacillus and Leptospirillum, were detected at low abundances. Also, bacteria not associated with extremely acidic, metal-rich environments were found. After enrichment in iron- and sulfur-oxidizing media, we isolated and identified a novel psychrotolerant Acidithiobacillus ferrivorans strain ACH. This strain can grow using ferrous iron, sulfur, thiosulfate, tetrathionate and pyrite, as energy sources. Optimal growth was observed in the presence of pyrite, where cultures reached a cell number of 6.5 · 10(7) cells mL(-1). Planktonic cells grown with pyrite showed the presence of extracellular polymeric substances (10 °C and 28 °C), and a high density of cells attached to pyrite grains were observed at 10 °C by electron microscopy. The attachment of cells to pyrite coupons and the presence of capsular polysaccharides were visualized by using epifluorescence microscopy, through nucleic acid and lectin staining with Syto(®)9 and TRITC-Con A, respectively. Interestingly, we observed high cell adhesion including the formation of microcolonies within 21 days of incubation at 4 °C, which was correlated with a clear induction of capsular polysaccharides production. Our data suggests that attachment to pyrite is not temperature-dependent in At. ferrivorans ACH. The results of this study highlight the potential of this novel psychrotolerant strain in oxidation and attachment to minerals under low-temperature conditions.

  9. Molecular Systematics of the Genus Acidithiobacillus: Insights into the Phylogenetic Structure and Diversification of the Taxon.

    PubMed

    Nuñez, Harold; Moya-Beltrán, Ana; Covarrubias, Paulo C; Issotta, Francisco; Cárdenas, Juan Pablo; González, Mónica; Atavales, Joaquín; Acuña, Lillian G; Johnson, D Barrie; Quatrini, Raquel

    2017-01-01

    The acidithiobacilli are sulfur-oxidizing acidophilic bacteria that thrive in both natural and anthropogenic low pH environments. They contribute to processes that lead to the generation of acid rock drainage in several different geoclimatic contexts, and their properties have long been harnessed for the biotechnological processing of minerals. Presently, the genus is composed of seven validated species, described between 1922 and 2015: Acidithiobacillus thiooxidans, A. ferrooxidans, A. albertensis, A. caldus, A. ferrivorans, A. ferridurans, and A. ferriphilus. However, a large number of Acidithiobacillus strains and sequence clones have been obtained from a variety of ecological niches over the years, and many isolates are thought to vary in phenotypic properties and cognate genetic traits. Moreover, many isolates remain unclassified and several conflicting specific assignments muddle the picture from an evolutionary standpoint. Here we revise the phylogenetic relationships within this species complex and determine the phylogenetic species boundaries using three different typing approaches with varying degrees of resolution: 16S rRNA gene-based ribotyping, oligotyping, and multi-locus sequencing analysis (MLSA). To this end, the 580 16S rRNA gene sequences affiliated to the Acidithiobacillus spp. were collected from public and private databases and subjected to a comprehensive phylogenetic analysis. Oligotyping was used to profile high-entropy nucleotide positions and resolve meaningful differences between closely related strains at the 16S rRNA gene level. Due to its greater discriminatory power, MLSA was used as a proxy for genome-wide divergence in a smaller but representative set of strains. Results obtained indicate that there is still considerable unexplored diversity within this genus. At least six new lineages or phylotypes, supported by the different methods used herein, are evident within the Acidithiobacillus species complex. Although the diagnostic

  10. Molecular Systematics of the Genus Acidithiobacillus: Insights into the Phylogenetic Structure and Diversification of the Taxon

    PubMed Central

    Nuñez, Harold; Moya-Beltrán, Ana; Covarrubias, Paulo C.; Issotta, Francisco; Cárdenas, Juan Pablo; González, Mónica; Atavales, Joaquín; Acuña, Lillian G.; Johnson, D. Barrie; Quatrini, Raquel

    2017-01-01

    The acidithiobacilli are sulfur-oxidizing acidophilic bacteria that thrive in both natural and anthropogenic low pH environments. They contribute to processes that lead to the generation of acid rock drainage in several different geoclimatic contexts, and their properties have long been harnessed for the biotechnological processing of minerals. Presently, the genus is composed of seven validated species, described between 1922 and 2015: Acidithiobacillus thiooxidans, A. ferrooxidans, A. albertensis, A. caldus, A. ferrivorans, A. ferridurans, and A. ferriphilus. However, a large number of Acidithiobacillus strains and sequence clones have been obtained from a variety of ecological niches over the years, and many isolates are thought to vary in phenotypic properties and cognate genetic traits. Moreover, many isolates remain unclassified and several conflicting specific assignments muddle the picture from an evolutionary standpoint. Here we revise the phylogenetic relationships within this species complex and determine the phylogenetic species boundaries using three different typing approaches with varying degrees of resolution: 16S rRNA gene-based ribotyping, oligotyping, and multi-locus sequencing analysis (MLSA). To this end, the 580 16S rRNA gene sequences affiliated to the Acidithiobacillus spp. were collected from public and private databases and subjected to a comprehensive phylogenetic analysis. Oligotyping was used to profile high-entropy nucleotide positions and resolve meaningful differences between closely related strains at the 16S rRNA gene level. Due to its greater discriminatory power, MLSA was used as a proxy for genome-wide divergence in a smaller but representative set of strains. Results obtained indicate that there is still considerable unexplored diversity within this genus. At least six new lineages or phylotypes, supported by the different methods used herein, are evident within the Acidithiobacillus species complex. Although the diagnostic

  11. Effects of ferrous sulfate, inoculum history, and anionic form on lead, zinc, and copper toxicity to Acidithiobacillus caldus strain BC13.

    PubMed

    Aston, John E; Peyton, Brent M; Lee, Brady D; Apel, William A

    2010-12-01

    The current study reports the single and combined toxicities of Pb, Zn, and Cu to Acidithiobacillus caldus strain BC13. The observed half-maximal inhibitory concentrations (IC50), ± 95% confidence intervals, for Pb, Zn, and Cu were 0.9 ± 0.1 mM, 39 ± 0.5 mM, and 120 ± 8 mM, respectively. The observed minimum inhibitory concentrations (MIC) for Pb, Zn, and Cu were 7.5 mM, 75 mM, and 250 mM, respectively. When metals were presented in binary mixtures, the toxicities were less than additive. For example, when 50% of the Pb MIC and 50% of the Cu MIC were presented together, the specific growth rate was inhibited by only 59 ± 3%, rather than 100%. In addition, the presence of ferrous iron in the growth media decreased Pb and Zn toxicity to A. caldus strain BC13. The importance of inoculum history was evaluated by pre-adapting cultures through subsequent transfers in the presence of Pb, Zn, and Cu at their respective IC50s. After pre-adaptation, cultures had specific growth rates 39 ± 11, 32 ± 7, and 28 ± 12% higher in the presence of Pb, Zn, and Cu IC50s, respectively, compared with cultures that had not been pre-adapted. In addition, when cells exposed to the MICs of Pb, Zn, and Cu were harvested, washed, and re-inoculated into fresh, metal-free medium, they grew, showing that the cells remained viable with little residual toxicity. Finally, metal chlorides showed more toxicity than metal sulfates, and studies using sodium chloride or a mixture of metal sulfates and sodium chloride suggested that this was attributable to an additive combination of the metal and chloride toxicities.

  12. Effects of ferrous sulfate, inoculum history, and anionic form on lead, zinc, and copper toxicity to Acidithiobacillus caldus strain BC13

    SciTech Connect

    John E. Aston; William A. Apel; Brady D. Lee; Brent M. Peyton

    2010-12-01

    The current study reports the single and combined toxicities of Pb, Zn, and Cu to Acidithiobacillus caldus strain BC13. The observed half-maximal inhibitory concentrations (IC50),?±?95% confidence intervals, for Pb, Zn, and Cu were 0.9?±?0.1?mM, 39?±?0.5?mM, and 120?±?8?mM, respectively. The observed minimum inhibitory concentrations (MIC) for Pb, Zn, and Cu were 7.5?mM, 75?mM, and 250?mM, respectively. When metals were presented in binary mixtures, the toxicities were less than additive. For example, when 50% of the Pb MIC and 50% of the Cu MIC were presented together, the specific growth rate was inhibited by only 59?±?3%, rather than 100%. In addition, the presence of ferrous iron in the growth media decreased Pb and Zn toxicity to A. caldus strain BC13. The importance of inoculum history was evaluated by pre-adapting cultures through subsequent transfers in the presence of Pb, Zn, and Cu at their respective IC50s. After pre-adaptation, cultures had specific growth rates 39?±?11, 32?±?7, and 28?±?12% higher in the presence of Pb, Zn, and Cu IC50s, respectively, compared with cultures that had not been pre-adapted. In addition, when cells exposed to the MICs of Pb, Zn, and Cu were harvested, washed, and re-inoculated into fresh, metal-free medium, they grew, showing that the cells remained viable with little residual toxicity. Finally, metal chlorides showed more toxicity than metal sulfates, and studies using sodium chloride or a mixture of metal sulfates and sodium chloride suggested that this was attributable to an additive combination of the metal and chloride toxicities. Environ. Toxicol. Chem. 2010;29:2669–2675. © 2010 SETAC

  13. Recovery of Nickel and Cobalt from Laterite Tailings by Reductive Dissolution under Aerobic Conditions Using Acidithiobacillus Species.

    PubMed

    Marrero, J; Coto, O; Goldmann, S; Graupner, T; Schippers, A

    2015-06-02

    Biomining of sulfidic ores has been applied for almost five decades. However, the bioprocessing of oxide ores such as laterites lags commercially behind. Recently, the Ferredox process was proposed to treat limonitic laterite ores by means of anaerobic reductive dissolution (AnRD), which was found to be more effective than aerobic bioleaching by fungi and other bacteria. We show here that the ferric iron reduction mediated by Acidithiobacillus thiooxidans can be applied to an aerobic reductive dissolution (AeRD) of nickel laterite tailings. AeRD using a consortium of Acidithiobacillus thiooxidans and Acidithiobacillus ferrooxidans extracted similar amounts of nickel (53-57%) and cobalt (55-60%) in only 7 days as AnRD using Acidithiobacillus ferrooxidans. The economic and environmental advantages of AeRD for processing of laterite tailings comprise no requirement for an anoxic atmosphere, 1.8-fold less acid consumption than for AnRD, as well as nickel and cobalt recovered in a ferrous-based pregnant leach solution (PLS), facilitating the subsequent metal recovery. In addition, an aerobic acid regeneration stage is proposed. Therefore, AeRD process development can be considered as environmentally friendly for treating laterites with low operational costs and as an attractive alternative to AnRD.

  14. Evaluation of Leptospirillum ferrooxidans for Leaching

    PubMed Central

    Sand, Wolfgang; Rohde, Katrin; Sobotke, Birgit; Zenneck, Claus

    1992-01-01

    The importance of Leptospirillum ferrooxidans for leach processes has been evaluated by studying the lithotrophic flora of three mine biotopes and a heap leaching operation, by percolation experiments with inoculated, sterilized ore, and by morphological, physiological, and genetic investigations of pure and mixed cultures of L. ferrooxidans, Thiobacillus ferrooxidans, and Thiobacillus thiooxidans. In biotopes of 20°C or above, Leptospirillum-like bacteria are as abundant as T. ferrooxidans. Leptospirilli represent at least one-half of the ferrous-iron-oxidizing population. Percolation experiments confirmed this result. Leptospirilli were as numerous as T. ferrooxidans. At reduced temperatures, the generation times of leptospirilli increase more so than those of T. ferrooxidans. At 14°C, Leptospirillum grows slowly and T. ferrooxidans dominates the population. Physiological investigations indicate that L. ferrooxidans is a strict chemolithoautotroph, metabolizing only ferrous iron and pyrite. Even an addition of 0.05% (wt/vol) yeast extract inhibited its growth. The maximum ferrous-iron-oxidizing activity of L. ferrooxidans amounts to about 40% of the activity of T. ferrooxidans. After growth on sulfidic ore, both species exhibit reduced iron-oxidizing activities, L. ferrooxidans exhibiting one-third and T. ferrooxidans exhibiting one-seventh of their maximum activities. Surprisingly, the absolute values are similar. For indirect leaching, L. ferrooxidans is as important as T. ferrooxidans. This was confirmed by the results of percolation experiments. L. ferrooxidans together with T. thiooxidans mobilized metals at least as well as T. ferrooxidans did. The best results were obtained with a mixed culture of all three species. Images PMID:16348642

  15. Bioleaching of metals from steel slag by Acidithiobacillus thiooxidans culture supernatant.

    PubMed

    Hocheng, Hong; Su, Cheer; Jadhav, Umesh U

    2014-12-01

    The generation of 300–500 kg of slag per ton of the steel produced is a formidable amount of solid waste available for treatment. They usually contain considerable quantities of valuable metals. In this sense, they may become either important secondary resource if processed in eco-friendly manner for secured supply of contained metals or potential pollutants, if not treated properly. It is possible to recover metals from steel slag by applying bioleaching process. Electric arc furnace (EAF) slag sample was used for bioleaching of metals. In the present study, before bioleaching experiment water washing of an EAF slag was carried out. This reduced slag pH from 11.2 to 8.3. Culture supernatants of Acidithiobacillus thiooxidans (At. thiooxidans), Acidithiobacillus ferrooxidans (At. ferrooxidans), and Aspergillus niger (A. niger) were used for metal solubilization. At. thiooxidans culture supernatant containing 0.016 M sulfuric acid was found most effective for bioleaching of metals from an EAF slag. Maximum metal extraction was found for Mg (28%), while it was least for Mo (0.1%) in six days. Repeated bioleaching cycles increased metal recovery from 28% to 75%, from 14% to 60% and from 11% to 27%, for Mg, Zn and Cu respectively.

  16. The role of higher polythionates in the reduction of chromium(VI) by Acidithiobacillus and Thiobacillus cultures.

    PubMed

    Allegretti, P; Furlong, J; Donati, E

    2006-03-09

    In this paper, we report the chromium(VI) reduction by filtrates of Acidithiobacillus and Thiobacillus cultures. Chromium(VI) reduction by filtrates of A. ferrooxidans cultures under acidic conditions was higher than that observed for A. thiooxidans. However, at pH close to 7, chromium(VI) reduction by filtrates of T. thioparus cultures was as high as that by filtrates of A. thiooxidans cultures and much higher than that observed for A. ferrooxidans cultures at the same pH. The capability of these cultures to reduce chromium(VI) was associated specifically with the fraction of cultures (cells, sulphur and associated sulphur compounds) retained by filtration through a 0.45mum filter. In the fraction that comes from A. thiooxidans culture, polythionates (S(x)O(6)(2-)) with 3-7 sulphur atoms were detected and identified (by HPLC with MS as detector). The model of vesicles containing polythionates, sulphur and water agrees with our results.

  17. Improved chalcopyrite bioleaching by Acidithiobacillus sp. via direct step-wise regulation of microbial community structure.

    PubMed

    Feng, Shoushuai; Yang, Hailin; Wang, Wu

    2015-09-01

    A direct step-wise regulation strategy of microbial community structure was developed for improving chalcopyrite bioleaching by Acidithiobacillus sp. Specially, the initial microbial proportion between Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans was controlled at 3:1 with additional 2 g/L Fe(2+) for faster initiating iron metabolism. A. thiooxidans biomass was fed via a step-wise strategy (8-12th d) with the microbial proportion 1:1 for balancing community structure and promoting sulfur metabolism in the stationary phase. A. thiooxidans proportion was further improved via another step-wise feeding strategy (14-18th d) with the microbial proportion 1:2 for enhancing sulfur metabolism and weakening jarosite passivation in the later phase. With the community structure-shift control strategy, biochemical reaction was directly regulated for creating a better balance in different phases. Moreover, the final copper ion was increased from 57.1 to 93.2 mg/L, with the productivity 2.33 mg/(Ld). The novel strategy may be valuable in optimization of similar bioleaching process.

  18. [Inhibition of Low Molecular Organic Acids on the Activity of Acidithiobacillus Species and Its Effect on the Removal of Heavy Metals from Contaminated Soil].

    PubMed

    Song, Yong-wei; Wang, He-rul; Cao, Yan-xiao; Li, Fei; Cui, Chun-hong; Zhou, Li

    2016-05-15

    Application of organic fertilizer can reduce the solubility and bioavailability of heavy metals in contaminated soil, but in the flooded anaerobic environment, organic fertilizer will be decomposed to produce a large number of low molecular organic acids, which can inhibit the biological activity of Acidithiobacillus species. Batch cultures studies showed that the monocarboxylic organic acids including formic acid, acetic acid, propionic acid, and butyric acid exhibited a marked toxicity to Acidithiobacillus species, as indicated by that 90% of inhibitory rate for Fe2 and So oxidation in 72 h were achieved at extremely low concentrations of 41.2 mg · L⁻¹, 78.3 mg · L⁻¹, 43.2 mg · L⁻¹, 123.4 mg · L⁻¹ and 81.9 mg 230. 4 mg · L⁻¹, 170.1 mg · L⁻¹, 123.4 mg · L⁻¹ respectively. Of these organic acids, formic acid was the most toxic one as indicated by that Fe2 and So oxidation was almost entirely inhibited at a low concentration. In addition, it was found that Acidithiobacillus ferrooxidans was more sensitive to low molecular organic acids than Acidithiobacillus thiooxidans. What's more, there was little effect on biological acidification process of heavy metal contaminated soil when organic acids were added at initial stage (Oh), but it was completely inhibited when these acids were added after 12 h of conventional biological acidification, thus decreasing the efficiency of heavy metals dissolution from soil.

  19. Biogeography of sulfur-oxidizing Acidithiobacillus populations in extremely acidic cave biofilms

    PubMed Central

    Jones, Daniel S; Schaperdoth, Irene; Macalady, Jennifer L

    2016-01-01

    Extremely acidic (pH 0–1.5) Acidithiobacillus-dominated biofilms known as snottites are found in sulfide-rich caves around the world. Given the extreme geochemistry and subsurface location of the biofilms, we hypothesized that snottite Acidithiobacillus populations would be genetically isolated. We therefore investigated biogeographic relationships among snottite Acidithiobacillus spp. separated by geographic distances ranging from meters to 1000s of kilometers. We determined genetic relationships among the populations using techniques with three levels of resolution: (i) 16S rRNA gene sequencing, (ii) 16S–23S intergenic transcribed spacer (ITS) region sequencing and (iii) multi-locus sequencing typing (MLST). We also used metagenomics to compare functional gene characteristics of select populations. Based on 16S rRNA genes, snottites in Italy and Mexico are dominated by different sulfur-oxidizing Acidithiobacillus spp. Based on ITS sequences, Acidithiobacillus thiooxidans strains from different cave systems in Italy are genetically distinct. Based on MLST of isolates from Italy, genetic distance is positively correlated with geographic distance both among and within caves. However, metagenomics revealed that At. thiooxidans populations from different cave systems in Italy have different sulfur oxidation pathways and potentially other significant differences in metabolic capabilities. In light of those genomic differences, we argue that the observed correlation between genetic and geographic distance among snottite Acidithiobacillus populations is partially explained by an evolutionary model in which separate cave systems were stochastically colonized by different ancestral surface populations, which then continued to diverge and adapt in situ. PMID:27187796

  20. Electrochemistry of Thiobacillus ferrooxidans reactions with pyrite

    SciTech Connect

    Pesic, B.; Oliver, D.J.; Kim, Inbeum; De, G.C.

    1993-01-20

    A cyclic voltammetry technique was used to study the interactions of pyrite during bioleaching with the bacterium Thiobacillus ferrooxidans. Potential effects of heavy metals (silver and mercury) and varying the pH on the iron oxidizing ability of the bacterium are reported. Redox potential techniques were used to study effect of ferrous sulfate concentration and pH on bacterial growth.

  1. Characterization of uranium mine isolates and laboratory cultures of Thiobacillus ferrooxidans with emphasis on the oxidation and cellular accumulation of uranium and bioenergetic comparison with iron

    SciTech Connect

    Dispirito, A.A.

    1983-01-01

    Five strains of Thiobacillus ferrooxidans, which included three recent isolates from a uranium mine, possessed flagella. Both polar and peritrichous flagella were observed, indicating strain-dependent ultrastructural variation in acidophilic thiobacilli. The oxidation of uranous compounds by washed cell suspensions of T. ferrooxidans and T. acidophilus was monitored with a Clark oxygen electrode. The rates of oxygen uptake were dependent on: the cell concentration; the previous growth history of the organism; the amounts of U-IV and of inhibitors; pH and the presence of iron sulfates. The stoichiometric oxidation of uranous- to uranyl-uranium by T. ferrooxidans was demonstrated. Fixation of /sup 14/CO/sub 2/ and the effect of inhibitors demonstrate that energy is conserved during the oxidation and used for energy-dependent reverse electron flow and carbon dioxide fixation. Kinetic constants for the oxidation of uranous and ferrous ions by T. ferrooxidans were estimated. Isoprenoid quinones were extracted from T. ferrooxidans by three different methods. The uptake and cellular distribution of UO/sub 2//sup 2 +/ was investigated in washed cell suspension of T. ferrooxidans.

  2. Electrochemistry of Thiobacillus ferrooxidans reactions with pyrite

    SciTech Connect

    Pesic, B.

    1991-01-01

    The interactions of mineral-pyrite with T. ferrooxidans were studied by using a cyclic voltametry technique. The interactions with bacteria were examined during the entire growth stage of bacterial (fermentation). The pyrite surface invariably drastically changed its properties at the second day of fermentation. Beyond two days of fermentation, the cyclic voltamograms were insensitive to convective diffusion produced by stirring. The product layer was examined by SEM, X-ray diffraction and chemical analysis. The SEM study revealed that bacteria populated the pyrite surface at an extremely high density levels. The high density of bacteria, and the solid reaction products formed on the pyrite surface created conditions for pore diffusion which explained why the CVs became insensitive to convective diffusion in solution (stirring). The X-ray diffraction study confirmed jarosite as a product layer. A mechanism of T. ferrooxidans cells serving as nucleation sites for jarosite formation is proposed. 16 refs., 8 figs., 2 tabs.

  3. [Biomachining of metal copper by Thiobacillus ferrooxidans].

    PubMed

    Li, Y; Zhang, D; Wu, Y

    2000-06-01

    Thiobacillus ferrooxidans was employed in the biomachining process of metal copper(Cu0). The bacteria growth and the changes of Fe3+ concentration during machining processes have been studied. Biomachining and chemical machining have been compared. The results showed that the concentrations of bacteria and Fe3+ determine the speed of machining copper. The biomachining is more fast that chemical maching because bacteria are able to regenerate Fe3+ oxidizing copper. It was also found that the Cu2+ produced from the machining processes inhibit the growth of bacteria. Cu2+ has to be removed.

  4. Biosynthesis of bifunctional iron oxyhydrosulfate by Acidithiobacillus ferroxidans and their application to coagulation and adsorption.

    PubMed

    Gan, Min; Song, Zibo; Jie, Shiqi; Zhu, Jianyu; Zhu, Yaowu; Liu, Xinxing

    2016-02-01

    Coagulation and adsorption are important environmental technologies, which were widely applied in water treatment. In this study, a type of villous iron oxyhydrosulfate with low crystallinity, high content iron, sulfate and hydroxyl was synthesized by Acidithiobacillus ferrooxidans, which possessed coagulation and heavy metal adsorption ability simultaneously. The results showed that the Cu(II) adsorption capacity increased within a small range over the pH range of 3.0-5.0 but increased evidently over the range of 6.0-8.0. The maximal Cu(II) adsorption capacity of sample Af and Gf reached 50.97 and 46.08mg/g respectively. The optimum pH for Cr(VI) adsorption was 6.0, and the maximal adsorption capacity reached 51.32 and 59.57mg/g. The Langmuir isotherm can better describe the adsorption behavior of Cr(VI). Coagulation performance of the iron oxyhydrosulfate (Sh) has been significantly enhanced by polysilicic acid (PSA), which was mainly determined by PSA/Sh ratio, pH and coagulant dosage. Coagulation efficiency maintained approximately at 98% when the PSA/Sh ratio ranged from 0.4/0.1 to 1.0/0.1. Polysilicic acid worked efficiently in wide pH range extending, from 2 to 3.5. Coagulation performance improved significantly with the increasing of the coagulant dosage at lower dosage range, while, at higher dosage range, the improvement was not evident even with more coagulant addition.

  5. Reduction of Cupric Ions with Elemental Sulfur by Thiobacillus ferrooxidans.

    PubMed

    Sugio, T; Tsujita, Y; Inagaki, K; Tano, T

    1990-03-01

    In anaerobic or aerobic conditions in the presence of 5 mM sodium cyanide, an inhibitor of iron oxidase, cupric ion (Cu) was reduced enzymatically with elemental sulfur (S) by washed intact cells of Thiobacillus ferrooxidans AP19-3 to give cuprous ion (Cu). The rate of Cu reduction was proportional to the concentrations of S and Cu added to the reaction mixture. The pH optimum for the cupric ion-reducing system was 5.0, and the activity was completely destroyed by 10-min incubation of cells at 70 degrees C. The activity of Cu reduction with S by this strain was strongly inhibited by inhibitors of hydrogen sulfide: ferric ion oxidoreductase (SFORase), such as alpha,alpha'-dipyridyl, 4,5-dihydroxy-m-benzene disulfonic acid disodium salts, and diazine dicarboxylic acid bis-(N, N-dimethylamide). A SFORase purified from this strain, which catalyzes oxidation of both hydrogen sulfide and S with Fe or Mo as an electron acceptor in the presence of glutathione, catalyzed a reduction of Cu by S, and the Michaelis constant of SFORase for Cu was 7.2 mM, indicating that a SFORase catalyzes the reduction of not only Fe and Mo but also Cu.

  6. Reduction of Cupric Ions with Elemental Sulfur by Thiobacillus ferrooxidans

    PubMed Central

    Sugio, Tsuyoshi; Tsujita, Yoshihiko; Inagaki, Kenji; Tano, Tatsuo

    1990-01-01

    In anaerobic or aerobic conditions in the presence of 5 mM sodium cyanide, an inhibitor of iron oxidase, cupric ion (Cu2+) was reduced enzymatically with elemental sulfur (S0) by washed intact cells of Thiobacillus ferrooxidans AP19-3 to give cuprous ion (Cu+). The rate of Cu2+ reduction was proportional to the concentrations of S0 and Cu2+ added to the reaction mixture. The pH optimum for the cupric ion-reducing system was 5.0, and the activity was completely destroyed by 10-min incubation of cells at 70°C. The activity of Cu2+ reduction with S0 by this strain was strongly inhibited by inhibitors of hydrogen sulfide: ferric ion oxidoreductase (SFORase), such as α,α′-dipyridyl, 4,5-dihydroxy-m-benzene disulfonic acid disodium salts, and diazine dicarboxylic acid bis-(N, N-dimethylamide). A SFORase purified from this strain, which catalyzes oxidation of both hydrogen sulfide and S0 with Fe3+ or Mo6+ as an electron acceptor in the presence of glutathione, catalyzed a reduction of Cu2+ by S0, and the Michaelis constant of SFORase for Cu2+ was 7.2 mM, indicating that a SFORase catalyzes the reduction of not only Fe3+ and Mo6+ but also Cu2+. PMID:16348143

  7. Leaching of pyrites of various reactivities by Thiobacillus ferrooxidans

    SciTech Connect

    Baldi, F. ); Clark, T.; Pollack, S.S.; Olson, G.J. )

    1992-06-01

    Variations were found in the rate of chemical and microbiological leaching of iron from pyritic materials from various sources. Thiobacillus ferrooxidans accelerated leaching of iron from all of the pyritic materials tested in shake flask suspensions at loadings of 0.4% (wt/vol) pulp density. The most chemically reactive pyrites exhibited the fastest bioleaching rates. However, at 2.0% pulp density, a delay in onset of bioleaching occurred with two of the pyrites derived from coal sources. T. ferrooxidans was unable to oxidize the most chemically reactive pyrite at 2.0% pulp density. No inhibition of pyrite oxidation by T. ferrooxidans occurred with mineral pyrite at 2.0% pulp density. Experiments with the most chemically reactive pyrite indicated that the leachates from the material were not inhibitory to iron oxidation by T. ferrooxidans.

  8. Leaching of Pyrites of Various Reactivities by Thiobacillus ferrooxidans.

    PubMed

    Baldi, F; Clark, T; Pollack, S S; Olson, G J

    1992-06-01

    Wide variations were found in the rate of chemical and microbiological leaching of iron from pyritic materials from various sources. Thiobacillus ferrooxidans accelerated leaching of iron from all of the pyritic materials tested in shake flask suspensions at loadings of 0.4% (wt/vol) pulp density. The most chemically reactive pyrites exhibited the fastest bioleaching rates. However, at 2.0% pulp density, a delay in onset of bioleaching occurred with two of the pyrites derived from coal sources. T. ferrooxidans was unable to oxidize the most chemically reactive pyrite at 2.0% pulp density. No inhibition of pyrite oxidation by T. ferrooxidans occurred with mineral pyrite at 2.0% pulp density. Experiments with the most chemically reactive pyrite indicated that the leachates from the material were not inhibitory to iron oxidation by T. ferrooxidans.

  9. Leaching of Pyrites of Various Reactivities by Thiobacillus ferrooxidans

    PubMed Central

    Baldi, Franco; Clark, Thomas; Pollack, S. S.; Olson, Gregory J.

    1992-01-01

    Wide variations were found in the rate of chemical and microbiological leaching of iron from pyritic materials from various sources. Thiobacillus ferrooxidans accelerated leaching of iron from all of the pyritic materials tested in shake flask suspensions at loadings of 0.4% (wt/vol) pulp density. The most chemically reactive pyrites exhibited the fastest bioleaching rates. However, at 2.0% pulp density, a delay in onset of bioleaching occurred with two of the pyrites derived from coal sources. T. ferrooxidans was unable to oxidize the most chemically reactive pyrite at 2.0% pulp density. No inhibition of pyrite oxidation by T. ferrooxidans occurred with mineral pyrite at 2.0% pulp density. Experiments with the most chemically reactive pyrite indicated that the leachates from the material were not inhibitory to iron oxidation by T. ferrooxidans. PMID:16348718

  10. [Oxidation of sulfide minerals by Thiobacillus ferrooxidans].

    PubMed

    Malakhova, P T; Chebotarev, G M; Kovalenko, E V; Volkov, Iu A

    1981-01-01

    Samples of natural pyrites and sphalerites were subjected to the action of the mineral medium 9K with 1 g of Fe3+ per litre in the presence and in the absence of Thiobacillus ferrooxidans, and incubated at 28 degrees C under the stationary conditions for 30 days. The chemical composition of the solutions was studied after leaching as well as changes of the surfaces of monoliths. The deepest etching of surfaces with the formation of crusts and films of jarosite, limonite and goslarite occurs upon the combined action of bacteria and Fe3+ in regions of a fine-zonal structure enriched with an isomorphous arsenic admixture which are characterized by a defective weak structure. The pyrite and sphalerite from Charmitan with a higher arsenic and iron content were leached more than the pyrite and sphalerite from Kurgashincan. This was also corroborated by chemical analyses of leaching solutions and by monometric studies of crushed sulfide samples.

  11. Comparative Genomics of the Extreme Acidophile Acidithiobacillus thiooxidans Reveals Intraspecific Divergence and Niche Adaptation

    PubMed Central

    Zhang, Xian; Feng, Xue; Tao, Jiemeng; Ma, Liyuan; Xiao, Yunhua; Liang, Yili; Liu, Xueduan; Yin, Huaqun

    2016-01-01

    Acidithiobacillus thiooxidans known for its ubiquity in diverse acidic and sulfur-bearing environments worldwide was used as the research subject in this study. To explore the genomic fluidity and intraspecific diversity of Acidithiobacillus thiooxidans (A. thiooxidans) species, comparative genomics based on nine draft genomes was performed. Phylogenomic scrutiny provided first insights into the multiple groupings of these strains, suggesting that genetic diversity might be potentially correlated with their geographic distribution as well as geochemical conditions. While these strains shared a large number of common genes, they displayed differences in gene content. Functional assignment indicated that the core genome was essential for microbial basic activities such as energy acquisition and uptake of nutrients, whereas the accessory genome was thought to be involved in niche adaptation. Comprehensive analysis of their predicted central metabolism revealed that few differences were observed among these strains. Further analyses showed evidences of relevance between environmental conditions and genomic diversification. Furthermore, a diverse pool of mobile genetic elements including insertion sequences and genomic islands in all A. thiooxidans strains probably demonstrated the frequent genetic flow (such as lateral gene transfer) in the extremely acidic environments. From another perspective, these elements might endow A. thiooxidans species with capacities to withstand the chemical constraints of their natural habitats. Taken together, our findings bring some valuable data to better understand the genomic diversity and econiche adaptation within A. thiooxidans strains. PMID:27548157

  12. "Use of acidophilic bacteria of the genus Acidithiobacillus to biosynthesize CdS fluorescent nanoparticles (quantum dots) with high tolerance to acidic pH".

    PubMed

    Ulloa, G; Collao, B; Araneda, M; Escobar, B; Álvarez, S; Bravo, D; Pérez-Donoso, J M

    2016-12-01

    The use of bacterial cells to produce fluorescent semiconductor nanoparticles (quantum dots, QDs) represents a green alternative with promising economic potential. In the present work, we report for the first time the biosynthesis of CdS QDs by acidophilic bacteria of the Acidithiobacillus genus. CdS QDs were obtained by exposing A. ferrooxidans, A. thiooxidans and A. caldus cells to sublethal Cd(2+) concentrations in the presence of cysteine and glutathione. The fluorescence of cadmium-exposed cells moves from green to red with incubation time, a characteristic property of QDs associated with nanocrystals growth. Biosynthesized nanoparticles (NPs) display an absorption peak at 360nm and a broad emission spectra between 450 and 650nm when excited at 370nm, both characteristic of CdS QDs. Average sizes of 6 and 10nm were determined for green and red NPs, respectively. The importance of cysteine and glutathione on QDs biosynthesis in Acidithiobacillus was related with the generation of H2S. Interestingly, QDs produced by acidophilic bacteria display high tolerance to acidic pH. Absorbance and fluorescence properties of QDs was not affected at pH 2.0, a condition that totally inhibits the fluorescence of QDs produced chemically or biosynthesized by mesophilic bacteria (stable until pH 4.5-5.0). Results presented here constitute the first report of the generation of QDs with improved properties by using extremophile microorganisms.

  13. A Novel Mineral Flotation Process Using Thiobacillus ferrooxidans

    PubMed Central

    Nagaoka, Toru; Ohmura, Naoya; Saiki, Hiroshi

    1999-01-01

    Oxidative leaching of metals by Thiobacillus ferrooxidans has proven useful in mineral processing. Here, we report on a new use for T. ferrooxidans, in which bacterial adhesion is used to remove pyrite from mixtures of sulfide minerals during flotation. Under control conditions, the floatabilities of five sulfide minerals tested (pyrite, chalcocite, molybdenite, millerite, and galena) ranged from 90 to 99%. Upon addition of T. ferrooxidans, the floatability of pyrite was significantly suppressed to less than 20%. In contrast, addition of the bacterium had little effect on the floatabilities of the other minerals, even when they were present in relatively large quantities: their floatabilities remained in the range of 81 to 98%. T. ferrooxidans thus appears to selectively suppress pyrite floatability. As a consequence, 77 to 95% of pyrite was removed from mineral mixtures while 72 to 100% of nonpyrite sulfide minerals was recovered. The suppression of pyrite floatability was caused by bacterial adhesion to pyrite surfaces. When normalized to the mineral surface area, the number of cells adhering to pyrite was significantly larger than the number adhering to other minerals. These results suggest that flotation with T. ferrooxidans may provide a novel approach to mineral processing in which the biological functions involved in cell adhesion play a key role in the separation of minerals. PMID:10427053

  14. Sulfur Oxygenase Reductase (Sor) in the Moderately Thermoacidophilic Leaching Bacteria: Studies in Sulfobacillus thermosulfidooxidans and Acidithiobacillus caldus

    PubMed Central

    Janosch, Claudia; Remonsellez, Francisco; Sand, Wolfgang; Vera, Mario

    2015-01-01

    The sulfur oxygenase reductase (Sor) catalyzes the oxygen dependent disproportionation of elemental sulfur, producing sulfite, thiosulfate and sulfide. Being considered an “archaeal like” enzyme, it is also encoded in the genomes of some acidophilic leaching bacteria such as Acidithiobacillus caldus, Acidithiobacillus thiooxidans, Acidithiobacillus ferrivorans and Sulfobacillus thermosulfidooxidans, among others. We measured Sor activity in crude extracts from Sb. thermosulfidooxidans DSM 9293T. The optimum temperature for its oxygenase activity was achieved at 75 °C, confirming the “thermophilic” nature of this enzyme. Additionally, a search for genes probably involved in sulfur metabolism in the genome sequence of Sb. thermosulfidooxidans DSM 9293T was done. Interestingly, no sox genes were found. Two sor genes, a complete heterodisulfidereductase (hdr) gene cluster, three tetrathionate hydrolase (tth) genes, three sulfide quinonereductase (sqr), as well as the doxD component of a thiosulfate quinonereductase (tqo) were found. Seven At. caldus strains were tested for Sor activity, which was not detected in any of them. We provide evidence that an earlier reported Sor activity from At. caldus S1 and S2 strains most likely was due to the presence of a Sulfobacillus contaminant. PMID:27682113

  15. Sulfur Oxygenase Reductase (Sor) in the Moderately Thermoacidophilic Leaching Bacteria: Studies in Sulfobacillus thermosulfidooxidans and Acidithiobacillus caldus.

    PubMed

    Janosch, Claudia; Remonsellez, Francisco; Sand, Wolfgang; Vera, Mario

    2015-10-21

    The sulfur oxygenase reductase (Sor) catalyzes the oxygen dependent disproportionation of elemental sulfur, producing sulfite, thiosulfate and sulfide. Being considered an "archaeal like" enzyme, it is also encoded in the genomes of some acidophilic leaching bacteria such as Acidithiobacillus caldus, Acidithiobacillus thiooxidans, Acidithiobacillus ferrivorans and Sulfobacillus thermosulfidooxidans, among others. We measured Sor activity in crude extracts from Sb. thermosulfidooxidans DSM 9293(T). The optimum temperature for its oxygenase activity was achieved at 75 °C, confirming the "thermophilic" nature of this enzyme. Additionally, a search for genes probably involved in sulfur metabolism in the genome sequence of Sb. thermosulfidooxidans DSM 9293(T) was done. Interestingly, no sox genes were found. Two sor genes, a complete heterodisulfidereductase (hdr) gene cluster, three tetrathionate hydrolase (tth) genes, three sulfide quinonereductase (sqr), as well as the doxD component of a thiosulfate quinonereductase (tqo) were found. Seven At. caldus strains were tested for Sor activity, which was not detected in any of them. We provide evidence that an earlier reported Sor activity from At. caldus S1 and S2 strains most likely was due to the presence of a Sulfobacillus contaminant.

  16. Genome Analysis of the Biotechnologically Relevant Acidophilic Iron Oxidising Strain JA12 Indicates Phylogenetic and Metabolic Diversity within the Novel Genus “Ferrovum”

    PubMed Central

    Ullrich, Sophie R.; Poehlein, Anja; Tischler, Judith S.; González, Carolina; Ossandon, Francisco J.; Daniel, Rolf; Holmes, David S.; Schlömann, Michael; Mühling, Martin

    2016-01-01

    Background Members of the genus “Ferrovum” are ubiquitously distributed in acid mine drainage (AMD) waters which are characterised by their high metal and sulfate loads. So far isolation and microbiological characterisation have only been successful for the designated type strain “Ferrovum myxofaciens” P3G. Thus, knowledge about physiological characteristics and the phylogeny of the genus “Ferrovum” is extremely scarce. Objective In order to access the wider genetic pool of the genus “Ferrovum” we sequenced the genome of a “Ferrovum”-containing mixed culture and successfully assembled the almost complete genome sequence of the novel “Ferrovum” strain JA12. Phylogeny and Lifestyle The genome-based phylogenetic analysis indicates that strain JA12 and the type strain represent two distinct “Ferrovum” species. “Ferrovum” strain JA12 is characterised by an unusually small genome in comparison to the type strain and other iron oxidising bacteria. The prediction of nutrient assimilation pathways suggests that “Ferrovum” strain JA12 maintains a chemolithoautotrophic lifestyle utilising carbon dioxide and bicarbonate, ammonium and urea, sulfate, phosphate and ferrous iron as carbon, nitrogen, sulfur, phosphorous and energy sources, respectively. Unique Metabolic Features The potential utilisation of urea by “Ferrovum” strain JA12 is moreover remarkable since it may furthermore represent a strategy among extreme acidophiles to cope with the acidic environment. Unlike other acidophilic chemolithoautotrophs “Ferrovum” strain JA12 exhibits a complete tricarboxylic acid cycle, a metabolic feature shared with the closer related neutrophilic iron oxidisers among the Betaproteobacteria including Sideroxydans lithotrophicus and Thiobacillus denitrificans. Furthermore, the absence of characteristic redox proteins involved in iron oxidation in the well-studied acidophiles Acidithiobacillus ferrooxidans (rusticyanin) and Acidithiobacillus

  17. Electrochemistry of Thiobacillus ferrooxidans reactions with pyrite. Final report

    SciTech Connect

    Pesic, B.; Oliver, D.J.; Kim, Inbeum; De, G.C.

    1993-01-20

    A cyclic voltammetry technique was used to study the interactions of pyrite during bioleaching with the bacterium Thiobacillus ferrooxidans. Potential effects of heavy metals (silver and mercury) and varying the pH on the iron oxidizing ability of the bacterium are reported. Redox potential techniques were used to study effect of ferrous sulfate concentration and pH on bacterial growth.

  18. Agronomic effectiveness of biofertilizers with phosphate rock, sulphur and Acidithiobacillus for yam bean grown on a Brazilian tableland acidic soil.

    PubMed

    Stamford, N P; Santos, P R; Santos, C E S; Freitas, A D S; Dias, S H L; Lira, M A

    2007-04-01

    Phosphate rocks have low available P and soluble P fertilizers have been preferably used in plant crop production, although economic and effective P sources are needed. Experiments were carried out on a Brazilian Typic Fragiudult soil with low available P to evaluate the agronomic effectiveness of phosphate rock (PR) compared with soluble phosphate fertilizer. Yam bean (Pachyrhizus erosus) inoculated with rhizobia (strains NFB 747 and NFB 748) or not inoculated was the test crop. Biofertilizers were produced in field furrows by mixing phosphate rock (PR) and sulphur inoculated with Acidithiobacillus (S+Ac) in different rates (50, 100, 150 and 200 g S kg(-1) PR), with 60 days of incubation. Treatments were carried out with PR; biofertilizers B(50), B(100), B(150), B(200); triple super phosphate (TSP); B(200) without Acidithiobacillus and a control treatment without P application (P(0)). TSP and biofertilizers plus S inoculated with Acidithiobacillus increased plant growth. Soil acidity and available P increased when biofertilizers B(150) and B(200) were applied. We conclude that biofertilizers may be used as P source; however, long term use will reduce soil pH and potentially reduce crop growth.

  19. Chalcocite Oxidation and Coupled Carbon Dioxide Fixation by Thiobacillus ferrooxidans.

    PubMed

    Nielsen, A M; Beck, J V

    1972-03-10

    The reaction of cell suspensions of Thiobacillus ferrooxidans with pulverized chalcocite (Cu(2)S) in a Warburg manometric apparatus resulted in oxygen uptake accompanied by increased solubilization of copper and fixation of carbon dioxide. Since the only detectable oxidized products were cupric ions and the more oxidized form of the sulfide mineral, that is, digenite or covellite, the apparent source of energy for the carbon dioxide fixation was provided by the oxidation of the cuprous copper of the chalcocite.

  20. Biological effect of Acidithiobacillus thiooxidans on some potentially toxic elements during alteration of SON 68 nuclear glass

    NASA Astrophysics Data System (ADS)

    Bachelet, M.; Crovisier, J. L.; Stille, P.; Vuilleumier, S.; Geoffroy, V.

    2009-04-01

    Although underground nuclear waste repositories are not expected to be favourable places for microbial activity, one should not exclude localized action of extremophilic bacteria on some materials involved in the storage concept. Among endogenous or accidentally introduced acidophiles, some are susceptible to lead to a locally drastic decreased in pH, with potential consequences on materials corrosion. Experiments were performed with Acidithiobacillus thiooxidans on 100-125 m french reference nuclear glass SON68 grains in a mineral medium under static conditions during 60 days at 25degC. Growth medium was periodically renewed and analyzed by ICP-AES and ICP-MS spectrometry for both major, trace and ultra-trace elements. Biofilm formation was evidenced by confocal laser microscopy, staining DNA with ethidium bromide and exopolysaccharides with calcofluor white. Biofilm thickness around material grains exceeded 20 m under the chosen experimental conditions. It can be noticed that while numerous studies on biofilm formation upon interaction between Acidithiobacillus ferrooxidans and materials are found in the literature, evidence for biofilm formation is still scarce for the case of the acidophilic bacterium A. thiooxidans. Presence of biofilm is a key parameter for material alteration at the solid/solution interface in biotic systems. Indeed, various constitutive elements of materials trapped in the polyanionic polymer of biofilm may also influence the alteration process. In particular, biofilm may reduce the alteration rate of materials by forming a protective barrier at their surface (Aouad et al., 2008). In this study, glass alteration rates, determined using strontium as tracer, showed that the progressive formation of a biofilm on the surface of glass has a protective effect against its alteration. Uranium and rare earth elements (REE) are efficiently trapped in the biogenic compartment of the system (exopolysaccharides + bacterial cells). Besides, the ratio

  1. A new genome of Acidithiobacillus thiooxidans provides insights into adaptation to a bioleaching environment.

    PubMed

    Travisany, Dante; Cortés, María Paz; Latorre, Mauricio; Di Genova, Alex; Budinich, Marko; Bobadilla-Fazzini, Roberto A; Parada, Pilar; González, Mauricio; Maass, Alejandro

    2014-11-01

    Acidithiobacillus thiooxidans is a sulfur oxidizing acidophilic bacterium found in many sulfur-rich environments. It is particularly interesting due to its role in bioleaching of sulphide minerals. In this work, we report the genome sequence of At. thiooxidans Licanantay, the first strain from a copper mine to be sequenced and currently used in bioleaching industrial processes. Through comparative genomic analysis with two other At. thiooxidans non-metal mining strains (ATCC 19377 and A01) we determined that these strains share a large core genome of 2109 coding sequences and a high average nucleotide identity over 98%. Nevertheless, the presence of 841 strain-specific genes (absent in other At. thiooxidans strains) suggests a particular adaptation of Licanantay to its specific biomining environment. Among this group, we highlight genes encoding for proteins involved in heavy metal tolerance, mineral cell attachment and cysteine biosynthesis. Several of these genes were located near genetic motility genes (e.g. transposases and integrases) in genomic regions of over 10 kbp absent in the other strains, suggesting the presence of genomic islands in the Licanantay genome probably produced by horizontal gene transfer in mining environments.

  2. Acidithiobacillus caldus Sulfur Oxidation Model Based on Transcriptome Analysis between the Wild Type and Sulfur Oxygenase Reductase Defective Mutant

    PubMed Central

    Chen, Linxu; Ren, Yilin; Lin, Jianqun; Liu, Xiangmei; Pang, Xin; Lin, Jianqiang

    2012-01-01

    Background Acidithiobacillus caldus (A. caldus) is widely used in bio-leaching. It gains energy and electrons from oxidation of elemental sulfur and reduced inorganic sulfur compounds (RISCs) for carbon dioxide fixation and growth. Genomic analyses suggest that its sulfur oxidation system involves a truncated sulfur oxidation (Sox) system (omitting SoxCD), non-Sox sulfur oxidation system similar to the sulfur oxidation in A. ferrooxidans, and sulfur oxygenase reductase (SOR). The complexity of the sulfur oxidation system of A. caldus generates a big obstacle on the research of its sulfur oxidation mechanism. However, the development of genetic manipulation method for A. caldus in recent years provides powerful tools for constructing genetic mutants to study the sulfur oxidation system. Results An A. caldus mutant lacking the sulfur oxygenase reductase gene (sor) was created and its growth abilities were measured in media using elemental sulfur (S0) and tetrathionate (K2S4O6) as the substrates, respectively. Then, comparative transcriptome analysis (microarrays and real-time quantitative PCR) of the wild type and the Δsor mutant in S0 and K2S4O6 media were employed to detect the differentially expressed genes involved in sulfur oxidation. SOR was concluded to oxidize the cytoplasmic elemental sulfur, but could not couple the sulfur oxidation with the electron transfer chain or substrate-level phosphorylation. Other elemental sulfur oxidation pathways including sulfur diooxygenase (SDO) and heterodisulfide reductase (HDR), the truncated Sox pathway, and the S4I pathway for hydrolysis of tetrathionate and oxidation of thiosulfate in A. caldus are proposed according to expression patterns of sulfur oxidation genes and growth abilities of the wild type and the mutant in different substrates media. Conclusion An integrated sulfur oxidation model with various sulfur oxidation pathways of A. caldus is proposed and the features of this model are summarized. PMID:22984393

  3. Estimation of kinetic rates in batch Thiobacillus ferrooxidans cultures.

    PubMed

    Biagiola, S; Solsona, J; Milocco, R

    2001-11-17

    In this work, the key problem of estimation in bioprocesses when no structural model is available is dealt with. A nonlinear observer-based algorithm is developed in order to estimate kinetic rates in batch bioreactors. The algorithm uses the measurements of biomass concentration and either substrate concentration or redox potential to perform the estimation of the respective specific kinetic rates. For this purpose, a general mathematical model description of the process is provided. The estimation algorithm design is based on a nonlinear reduced-order observer. The observer performance is validated with experimental results on a Thiobacillus ferrooxidans batch culture.

  4. Specific dot-immunobinding assay for detection and enumeration of Thiobacillus ferrooxidans

    SciTech Connect

    Arredondo, R.; Jerez, C.A. )

    1989-08-01

    A specific and very sensitive dot-immunobinding assay for the detection and enumeration of the bioleaching microorganism Thiobacillus ferrooxidans was developed. Nitrocellulose spotted with samples was incubated with polyclonal antisera against whole T. ferrooxidans cells and then in {sup 125}I-labeled protein A or {sup 125}I-labeled goat antirabbit immunoglobulin G; incubation was followed by autoradiography. Since a minimum of 10{sup 3} cells per dot could be detected, the method offers the possibility of simultaneous processing of numerous samples in a short time to monitor the levels of T. ferrooxidans in bioleaching operations.

  5. Gene Turnover Contributes to the Evolutionary Adaptation of Acidithiobacillus caldus: Insights from Comparative Genomics

    PubMed Central

    Zhang, Xian; Liu, Xueduan; He, Qiang; Dong, Weiling; Zhang, Xiaoxia; Fan, Fenliang; Peng, Deliang; Huang, Wenkun; Yin, Huaqun

    2016-01-01

    Acidithiobacillus caldus is an extremely acidophilic sulfur-oxidizer with specialized characteristics, such as tolerance to low pH and heavy metal resistance. To gain novel insights into its genetic complexity, we chosen six A. caldus strains for comparative survey. All strains analyzed in this study differ in geographic origins as well as in ecological preferences. Based on phylogenomic analysis, we clustered the six A. caldus strains isolated from various ecological niches into two groups: group 1 strains with smaller genomes and group 2 strains with larger genomes. We found no obvious intraspecific divergence with respect to predicted genes that are related to central metabolism and stress management strategies between these two groups. Although numerous highly homogeneous genes were observed, high genetic diversity was also detected. Preliminary inspection provided a first glimpse of the potential correlation between intraspecific diversity at the genome level and environmental variation, especially geochemical conditions. Evolutionary genetic analyses further showed evidence that the difference in environmental conditions might be a crucial factor to drive the divergent evolution of A. caldus species. We identified a diverse pool of mobile genetic elements including insertion sequences and genomic islands, which suggests a high frequency of genetic exchange in these harsh habitats. Comprehensive analysis revealed that gene gains and losses were both dominant evolutionary forces that directed the genomic diversification of A. caldus species. For instance, horizontal gene transfer and gene duplication events in group 2 strains might contribute to an increase in microbial DNA content and novel functions. Moreover, genomes undergo extensive changes in group 1 strains such as removal of potential non-functional DNA, which results in the formation of compact and streamlined genomes. Taken together, the findings presented herein show highly frequent gene turnover of

  6. Mineral Products of Pyrrhotite Oxidation by Thiobacillus ferrooxidans.

    PubMed

    Bhatti, T M; Bigham, J M; Carlson, L; Tuovinen, O H

    1993-06-01

    The biological leaching of pyrrhotite (Fe(1-x)S) by Thiobacillus ferrooxidans was studied to characterize the oxidation process and to identify the mineral weathering products. The process was biphasic in that an initial phase of acid consumption and decrease in redox potential was followed by an acid-producing phase and an increase in redox potential. Elemental S was one of the first products of pyrrhotite degradation detected by X-ray diffraction. Pyrrhotite oxidation also yielded K-jarosite [KFe(3)(SO(4))(2)(OH)(6)], goethite (alpha-FeOOH), and schwertmannite [Fe(8)O(8)(OH)(6)SO(4)] as solid-phase products. Pyrrhotite was mostly depleted after 14 days, whereas impurities in the form of pyrite (cubic FeS(2)) and marcasite (orthorhombic FeS(2)) accumulated in the leach residue.

  7. Reduction of Mo6+ with elemental sulfur by Thiobacillus ferrooxidans.

    PubMed Central

    Sugio, T; Tsujita, Y; Katagiri, T; Inagaki, K; Tano, T

    1988-01-01

    In the presence of phosphate ions, molybdic ions (Mo6+) were reduced enzymatically with elemental sulfur by washed intact cells of Thiobacillus ferrooxidans to give molybdenum blue. The whole-cell activity that reduced Mo6+ was totally due to cellular sulfur:ferric ion oxidoreductase (SFORase) (T. Sugio, W. Mizunashi, K. Inagaki, and T. Tano, J. Bacteriol. 169:4916-4922, 1987). The activity of M06+ reduction with elemental sulfur was competitively inhibited by Fe3+, Cu2+, and Co2+. The Michaelis constant of SFORase for Mo6+ was 7.6 mM, and the inhibition constants for Fe3+, Cu2+, and Co2+ were 0.084, 0.015, and 0.17 mM, respectively, suggesting that SFORase can reduce not only Fe3+ and Mo6+ but also Cu2+ and Co2+ with elemental sulfur. PMID:3056928

  8. Corrosion and Electrochemical Oxidation of a Pyrite by Thiobacillus ferrooxidans

    PubMed Central

    Mustin, C.; Berthelin, J.; Marion, P.; de Donato, P.

    1992-01-01

    The oxidation of a pure pyrite by Thiobacillus ferrooxidans is not really a constant phenomenon; it must be considered to be more like a succession of different steps which need characterization. Electrochemical studies using a combination of a platinum electrode and a specific pyrite electrode (packed-ground-pyrite electrode) revealed four steps in the bioleaching process. Each step can be identified by the electrochemical behavior (redox potentials) of pyrite, which in turn can be related to chemical (leachate content), bacterial (growth), and physical (corrosion patterns) parameters of the leaching process. A comparison of the oxidation rates of iron and sulfur indicated the nonstoichiometric bacterial oxidation of a pure pyrite in which superficial phenomena, aqueous oxidation, and deep crystal dissolution are successively involved. Images PMID:16348688

  9. Mechanism of Pyrite Dissolution in the Presence of Thiobacillus ferrooxidans

    PubMed Central

    Fowler, T. A.; Holmes, P. R.; Crundwell, F. K.

    1999-01-01

    In spite of the environmental and commercial interests in the bacterial leaching of pyrite, two central questions have not been answered after more than 35 years of research: does Thiobacillus ferrooxidans enhance the rate of leaching above that achieved by ferric sulfate solutions under the same conditions, and if so, how do the bacteria affect such an enhancement? Experimental conditions of previous studies were such that the concentrations of ferric and ferrous ions changed substantially throughout the course of the experiments. This has made it difficult to interpret the data obtained from these previous works. The aim of this work was to answer these two questions by employing an experimental apparatus designed to maintain the concentrations in solution at a constant value. This was achieved by using the constant redox potential apparatus described previously (P. I. Harvey, and F. K. Crundwell, Appl. Environ. Microbiol. 63:2586–2592, 1997; T. A. Fowler, and F. K. Crundwell, Appl. Environ. Microbiol. 64:3570–3575, 1998). Experiments were conducted in both the presence and absence of T. ferrooxidans, maintaining the same conditions in solution. The rate of dissolution of pyrite with bacteria was higher than that without bacteria at the same concentrations of ferrous and ferric ions in solution. Analysis of the dependence of the rate of leaching on the concentration of ferric ions and on the pH, together with results obtained from electrochemical measurements, provided clear evidence that the higher rate of leaching with bacteria is due to the bacteria increasing the pH at the surface of the pyrite. PMID:10388693

  10. Architecture and Gene Repertoire of the Flexible Genome of the Extreme Acidophile Acidithiobacillus caldus

    PubMed Central

    Acuña, Lillian G.; Cárdenas, Juan Pablo; Covarrubias, Paulo C.; Haristoy, Juan José; Flores, Rodrigo; Nuñez, Harold; Riadi, Gonzalo; Shmaryahu, Amir; Valdés, Jorge; Dopson, Mark; Rawlings, Douglas E.; Banfield, Jillian F.; Holmes, David S.; Quatrini, Raquel

    2013-01-01

    Background Acidithiobacillus caldus is a sulfur oxidizing extreme acidophile and the only known mesothermophile within the Acidithiobacillales. As such, it is one of the preferred microbes for mineral bioprocessing at moderately high temperatures. In this study, we explore the genomic diversity of A. caldus strains using a combination of bioinformatic and experimental techniques, thus contributing first insights into the elucidation of the species pangenome. Principal Findings Comparative sequence analysis of A. caldus ATCC 51756 and SM-1 indicate that, despite sharing a conserved and highly syntenic genomic core, both strains have unique gene complements encompassing nearly 20% of their respective genomes. The differential gene complement of each strain is distributed between the chromosomal compartment, one megaplasmid and a variable number of smaller plasmids, and is directly associated to a diverse pool of mobile genetic elements (MGE). These include integrative conjugative and mobilizable elements, genomic islands and insertion sequences. Some of the accessory functions associated to these MGEs have been linked previously to the flexible gene pool in microorganisms inhabiting completely different econiches. Yet, others had not been unambiguously mapped to the flexible gene pool prior to this report and clearly reflect strain-specific adaption to local environmental conditions. Significance For many years, and because of DNA instability at low pH and recurrent failure to genetically transform acidophilic bacteria, gene transfer in acidic environments was considered negligible. Findings presented herein imply that a more or less conserved pool of actively excising MGEs occurs in the A. caldus population and point to a greater frequency of gene exchange in this econiche than previously recognized. Also, the data suggest that these elements endow the species with capacities to withstand the diverse abiotic and biotic stresses of natural environments, in particular

  11. Biodegradation of the french reference nuclear glass SON 68 by Acidithiobacillus thiooxidans : protective effect of the biofilm,U and REE retention

    NASA Astrophysics Data System (ADS)

    Bachelet, M.; Crovisier, J.; Stille, P.; Boutin, R.; Vuilleumier, S.; Geoffroy, V.

    2008-12-01

    Although underground nuclear waste repositories are not expected to be favourable places for microbial activity, one should not exclude localized action of extremophilic bacteria on some materials involved in the storage concept. Among endogenous or accidentally introduced acidophiles, some are susceptible to lead to a locally drastic decreased in pH with potential consequences on materials corrosion. Experiments were performed with Acidithiobacillus thiooxidans on 100-125 μm french reference nuclear glass SON68 grains in a mineral medium under static conditions during 60 days at 25°C. Growth medium was periodically renewed and analyzed by ICP-AES and ICP-MS spectrometry for both major, traces and ultra-traces elements. Biofilm formation was evidenced by confocal laser microscopy, staining DNA with ethidium bromide and exopolysaccharides with calcofluor white. Biofilm thickness around material grains exceeded 20 μm under the chosen experimental conditions. It can be noticed that while numerous studies on biofilm formation upon interaction between Acidithiobacillus ferrooxidans and materials can be found in the literature, evidence for biofilm formation is still scarce for the case of the acidophilic bacterium A. thiooxidans. Presence of biofilm is a key parameter for material alteration at the solid/solution interface in biotic systems. Indeed, various constitutive elements of materials trapped in the polyanionic polymer of biofilm may also influence the alteration process. In particular, biofilm may reduce the alteration rate of materials by forming a protective barrier at their surface (Aouad et al., 2008). In this study, glass alteration rates, determined using strontium, molybdenum and caesium as tracers, showed that the biofilm has a protective effect against glass alteration. U and REE are efficiently trapped in the biogenic compartment of the system (exopolysaccharides (EPS) + bacterial cells). Biofilm analysis are in progress to determine whether these

  12. Biosorption and biodegradation of a sulfur dye in high-strength dyeing wastewater by Acidithiobacillus thiooxidans.

    PubMed

    Nguyen, Thai Anh; Fu, Chun-Chieh; Juang, Ruey-Shin

    2016-11-01

    The ability of the bacterial strain Acidithiobacillus thiooxidans to remove sulfur blue 15 (SB15) dye from water samples was examined. This bacterium could not only oxidize sulfur compounds to sulfuric acid but also promote the attachment of the cells to the surface of sulfidic particles, therefore serving as an efficient biosorbent. The biosorption isotherms were better described by the Langmuir equation than by the Freundlich or Dubinin-Radushkevich equation. Also, the biosorption process followed the pseudo-second-order kinetics. At pH 8.3 and SB15 concentrations up to 2000 mg L(-1) in the biomass/mineral salt solution, the dye removal and decolorization were 87.5% and 91.4%, respectively, following the biosorption process. Biodegradation was proposed as a subsequent process for the remaining dye (250-350 mg L(-1)). A central composite design was used to analyze independent variables in the response surface methodology study. Under the optimal conditions (i.e., initial dye concentration of 300 mg L(-1), initial biomass concentration of 1.0 g L(-1), initial pH of 11.7, and yeast extract dose of 60 mg L(-1)), up to 50% of SB15 was removed after 4 days of biodegradation.

  13. Novel integration strategy for enhancing chalcopyrite bioleaching by Acidithiobacillus sp. in a 7-L fermenter.

    PubMed

    Feng, Shoushuai; Yang, Hailin; Zhan, Xiao; Wang, Wu

    2014-06-01

    An integrated strategy (additional energy substrate-three stage pH control-fed batch) was firstly proposed for efficiently improving chalcopyrite bioleaching by Acidithiobacillus sp. in a 7-L fermenter. The strain adaptive-growing phase was greatly shortened from 8days into 4days with the supplement of additional 2g/L Fe(2+)+2g/L S(0). Jarosite passivation was effectively weakened basing on higher biomass via the three-stage pH-stat control (pH 1.3-1.0-0.7). The mineral substrate inhibition was attenuated by fed-batch fermentation. With the integrated strategy, the biochemical reaction was promoted and achieved a better balance. Meanwhile, the domination course of A. thiooxidans in the microbial community was shortened from 14days to 8days. As the results of integrated strategy, the final copper ion and productivity reached 89.1mg/L and 2.23mg/(Ld), respectively, which was improved by 52.8% compared to the uncontrolled batch bioleaching. The integrated strategy could be further exploited for industrial chalcopyrite bioleaching.

  14. Ferrous iron oxidation by Thiobacillus ferrooxidans: inhibition with benzoic acid, sorbic acid and sodium lauryl sulfate

    SciTech Connect

    Onysko, S.J.

    1984-07-01

    Acid mine drainage is formed by the weathering or oxidation of pyritic material exposed during coal mining. The rate of pyritic material oxidation can be greatly accelerated by certain acidophilic bacteria such as Thiobacillus ferrooxidans which catalyse the oxidation of ferrous to ferric iron. A number of organic compounds, under laboratory conditions, can apparently inhibit both the oxidation of ferrous to ferric iron by T. ferrooxidans and the weathering of pyritic material by mixed cultures of acid mine drainage micro-organisms. Sodium lauryl sulphate (SLS), an anionic surfactant has proved effective in this respect. Benzoic acid, sorbic acid and SLS at low concentrations, each effectively inhibited bacterial oxidation of ferrous iron in batch cultures of T. ferrooxidans. The rate of chemical oxidation of ferrous iron in low pH, sterile, batch reactors was not substantially affected at the tested concentrations of any of the compounds.

  15. Nucleotide sequence of the gene encoding the nitrogenase iron protein of Thiobacillus ferrooxidans

    SciTech Connect

    Pretorius, I.M.; Rawlings, D.E.; O'Neill, E.G.; Jones, W.A.; Kirby, R.; Woods, D.R.

    1987-01-01

    The DNA sequence was determined for the cloned Thiobacillus ferrooxidans nifH and part of the nifD genes. The DNA chains were radiolabeled with (..cap alpha..-/sup 32/P)dCTP (3000 Ci/mmol) or (..cap alpha..-/sup 35/S)dCTP (400 Ci/mmol). A putative T. ferrooxidans nifH promoter was identified whose sequences showed perfect consensus with those of the Klebsiella pneumoniae nif promoter. Two putative consensus upstream activator sequences were also identified. The amino acid sequence was deduced from the DNA sequence. In a comparison of nifH DNA sequences from T. ferrooxidans and eight other nitrogen-fixing microbes, a Rhizobium sp. isolated from Parasponia andersonii showed the greatest homology (74%) and Clostridium pasteurianum (nifH1) showed the least homology (54%). In the comparison of the amino acid sequences of the Fe proteins, the Rhizobium sp. and Rhizobium japonicum showed the greatest homology (both 86%) and C. pasteurianum (nifH1 gene product) demonstrated the least homology (56%) to the T. ferrooxidans Fe protein.

  16. Cloning and expression of the Thiobacillus ferrooxidans glutamine synthetase gene in Escherichia coli

    SciTech Connect

    Barros, M.E.C.; Rawlings, D.E.; Woods, D.R.

    1985-12-01

    The glutamine synthetase (GS) gene glnA of Thiobacillus ferrooxidans was cloned on recombinant plasmid pMEB100 which enabled Escherichia coli glnA deletion mutants to utilize (NH/sub 4/)/sub 2/SO/sub 4/ as the sole source of nitrogen. High levels of GS-specific activity were obtained in the E. coli glnA deletion mutants containing the T. ferrooxidans GS gene. The cloned T. ferrooxidans DNA fragment containing the glnA gene activated histidase activity in an E. coli glnA glnL glnG deletion mutant containing the Klebsiella aerogenes hut operon. Plasmid pMEB100 also enabled the E. coli glnA glnL glnG deletion mutant to utilize arginine or low levels of glutamine as the sole source of nitrogen. There was no detectable DNA homology between the T. ferrooxidans glnA gene and the E. coli glnA gene.

  17. Existence of aa3-type ubiquinol oxidase as a terminal oxidase in sulfite oxidation of Acidithiobacillus thiooxidans.

    PubMed

    Sugio, Tsuyoshi; Hisazumi, Tomohiro; Kanao, Tadayoshi; Kamimura, Kazuo; Takeuchi, Fumiaki; Negishi, Atsunori

    2006-07-01

    It was found that Acidithiobacillus thiooxidans has sulfite:ubiquinone oxidoreductase and ubiquinol oxidase activities in the cells. Ubiquinol oxidase was purified from plasma membranes of strain NB1-3 in a nearly homogeneous state. A purified enzyme showed absorption peaks at 419 and 595 nm in the oxidized form and at 442 and 605 nm in the reduced form. Pyridine ferrohaemochrome prepared from the enzyme showed an alpha-peak characteristic of haem a at 587 nm, indicating that the enzyme contains haem a as a component. The CO difference spectrum of ubiquinol oxidase showed two peaks at 428 nm and 595 nm, and a trough at 446 nm, suggesting the existence of an aa(3)-type cytochrome in the enzyme. Ubiquinol oxidase was composed of three subunits with apparent molecular masses of 57 kDa, 34 kDa, and 23 kDa. The optimum pH and temperature for ubiquinol oxidation were pH 6.0 and 30 degrees C. The activity was completely inhibited by sodium cyanide at 1.0 mM. In contrast, the activity was inhibited weakly by antimycin A(1) and myxothiazol, which are inhibitors of mitochondrial bc(1) complex. Quinone analog 2-heptyl-4-hydoroxyquinoline N-oxide (HOQNO) strongly inhibited ubiquinol oxidase activity. Nickel and tungstate (0.1 mM), which are used as a bacteriostatic agent for A. thiooxidans-dependent concrete corrosion, inhibited ubiquinol oxidase activity 100 and 70% respectively.

  18. Effect of external pH perturbations on in vivo protein synthesis by the acidophilic bacterium Thiobacillus ferrooxidans.

    PubMed Central

    Amaro, A M; Chamorro, D; Seeger, M; Arredondo, R; Peirano, I; Jerez, C A

    1991-01-01

    The response of the obligate acidophilic bacterium Thiobacillus ferrooxidans to external pH changes is reported. When T. ferrooxidans cells grown at pH 1.5 were shifted to pH 3.5, there were several changes in the general protein synthesis pattern, including a large stimulation of the synthesis of a 36-kDa protein (p36). The apparent low isoelectric point of p36, its location in the membrane fraction, and its cross-reaction with anti-OmpC from Salmonella typhi suggested that it may be a porin whose expression is regulated by extracellular pH. Images PMID:1987171

  19. Occurrences at mineral-bacteria interface during oxidation of arsenopyrite by Thiobacillus ferrooxidans

    SciTech Connect

    Fernandez, M.G.M.; Mustin, C.; Berthelin, J.; Donato, P. de; Barres, O.; Marion, P.

    1995-04-05

    The combination of an improved bacterial desorption method, scanning electron microscopy (SEM), diffuse reflectance and transmission infrared Fourier transform spectroscopy, and a desorption-leaching device like high-pressure liquid chromatography (HPLC) was used to analyze bacterial populations and surface-oxidized phases during the arsenopyrite biooxidation by Thiobacillus ferrooxidans. The bacterial distribution, the physicochemical composition of the leachate, the evolution of corrosion patterns, and the nature and amount of the surface-oxidized chemical species characterized different behavior for each step of arsenopyrite bioleaching.

  20. Identification and structural analysis of a ribosomal RNA gene promoter from Thiobacillus ferrooxidans.

    PubMed

    Takamiya, M; Salazar, O; Vargas, D; Jedlicki, E; Orellana, O

    1990-10-15

    The 5'-terminus of a rRNA operon (rrnT2) from Thiobacillus ferrooxidans was characterized. The rRNA promoters from this microorganism were identified by means of a functional assay in Escherichia coli. DNA sequencing of the promoter region, upstream the 16 S rRNA gene, showed the presence of a consensus sequence for bacterial ribosomal promoters. Other features such as a 'discriminator' sequence, antiterminator elements and an upstream hexanucleotide common to several rRNA operons were also found. Two other putative transcription promoters were also identified.

  1. The Effect of Oxygen Supply on the Dual Growth Kinetics of Acidithiobacillus thiooxidans under Acidic Conditions for Biogas Desulfurization

    PubMed Central

    Namgung, Hyeong-Kyu; Song, JiHyeon

    2015-01-01

    In this study, to simulate a biogas desulfurization process, a modified Monod-Gompertz kinetic model incorporating a dissolved oxygen (DO) effect was proposed for a sulfur-oxidizing bacterial (SOB) strain, Acidithiobacillus thiooxidans, under extremely acidic conditions of pH 2. The kinetic model was calibrated and validated using experimental data obtained from a bubble-column bioreactor. The SOB strain was effective for H2S degradation, but the H2S removal efficiency dropped rapidly at DO concentrations less than 2.0 mg/L. A low H2S loading was effectively treated with oxygen supplied in a range of 2%–6%, but a H2S guideline of 10 ppm could not be met, even with an oxygen supply greater than 6%, when the H2S loading was high at a short gas retention time of 1 min and a H2S inlet concentration of 5000 ppm. The oxygen supply should be increased in the aerobic desulfurization to meet the H2S guideline; however, the excess oxygen above the optimum was not effective because of the decline in oxygen efficiency. The model estimation indicated that the maximum H2S removal rate was approximately 400 ppm/%-O2 at the influent oxygen concentration of 4.9% under the given condition. The kinetic model with a low DO threshold for the interacting substrates was a useful tool to simulate the effect of the oxygen supply on the H2S removal and to determine the optimal oxygen concentration. PMID:25633028

  2. Diguanylate cyclase null mutant reveals that C-Di-GMP pathway regulates the motility and adherence of the extremophile bacterium Acidithiobacillus caldus.

    PubMed

    Castro, Matías; Deane, Shelly M; Ruiz, Lina; Rawlings, Douglas E; Guiliani, Nicolas

    2015-01-01

    An understanding of biofilm formation is relevant to the design of biological strategies to improve the efficiency of the bioleaching process and to prevent environmental damages caused by acid mine/rock drainage. For this reason, our laboratory is focused on the characterization of the molecular mechanisms involved in biofilm formation in different biomining bacteria. In many bacteria, the intracellular levels of c-di-GMP molecules regulate the transition from the motile planktonic state to sessile community-based behaviors, such as biofilm development, through different kinds of effectors. Thus, we recently started a study of the c-di-GMP pathway in several biomining bacteria including Acidithiobacillus caldus. C-di-GMP molecules are synthesized by diguanylate cyclases (DGCs) and degraded by phosphodiesterases (PDEs). We previously reported the existence of intermediates involved in c-di-GMP pathway from different Acidithiobacillus species. Here, we report our work related to At. caldus ATCC 51756. We identified several putative-ORFs encoding DGC and PDE and effector proteins. By using total RNA extracted from At. caldus cells and RT-PCR, we demonstrated that these genes are expressed. We also demonstrated the presence of c-di-GMP by mass spectrometry and showed that genes for several of the DGC enzymes were functional by heterologous genetic complementation in Salmonella enterica serovar Typhimurium mutants. Moreover, we developed a DGC defective mutant strain (Δc1319) that strongly indicated that the c-di-GMP pathway regulates the swarming motility and adherence to sulfur surfaces by At. caldus. Together, our results revealed that At. caldus possesses a functional c-di-GMP pathway which could be significant for ores colonization during the bioleaching process.

  3. Diguanylate Cyclase Null Mutant Reveals That C-Di-GMP Pathway Regulates the Motility and Adherence of the Extremophile Bacterium Acidithiobacillus caldus

    PubMed Central

    Castro, Matías; Deane, Shelly M.; Ruiz, Lina; Rawlings, Douglas E.; Guiliani, Nicolas

    2015-01-01

    An understanding of biofilm formation is relevant to the design of biological strategies to improve the efficiency of the bioleaching process and to prevent environmental damages caused by acid mine/rock drainage. For this reason, our laboratory is focused on the characterization of the molecular mechanisms involved in biofilm formation in different biomining bacteria. In many bacteria, the intracellular levels of c-di-GMP molecules regulate the transition from the motile planktonic state to sessile community-based behaviors, such as biofilm development, through different kinds of effectors. Thus, we recently started a study of the c-di-GMP pathway in several biomining bacteria including Acidithiobacillus caldus. C-di-GMP molecules are synthesized by diguanylate cyclases (DGCs) and degraded by phosphodiesterases (PDEs). We previously reported the existence of intermediates involved in c-di-GMP pathway from different Acidithiobacillus species. Here, we report our work related to At. caldus ATCC 51756. We identified several putative-ORFs encoding DGC and PDE and effector proteins. By using total RNA extracted from At. caldus cells and RT-PCR, we demonstrated that these genes are expressed. We also demonstrated the presence of c-di-GMP by mass spectrometry and showed that genes for several of the DGC enzymes were functional by heterologous genetic complementation in Salmonella enterica serovar Typhimurium mutants. Moreover, we developed a DGC defective mutant strain (Δc1319) that strongly indicated that the c-di-GMP pathway regulates the swarming motility and adherence to sulfur surfaces by At. caldus. Together, our results revealed that At. caldus possesses a functional c-di-GMP pathway which could be significant for ores colonization during the bioleaching process. PMID:25689133

  4. Bacterial consortium for copper extraction from sulphide ore consisting mainly of chalcopyrite

    PubMed Central

    Romo, E.; Weinacker, D.F.; Zepeda, A.B.; Figueroa, C.A.; Chavez-Crooker, P.; Farias, J.G.

    2013-01-01

    The mining industry is looking forward for bacterial consortia for economic extraction of copper from low-grade ores. The main objective was to determine an optimal bacterial consortium from several bacterial strains to obtain copper from the leach of chalcopyrite. The major native bacterial species involved in the bioleaching of sulphide ore (Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, Leptospirillum ferrooxidans and Leptospirillum ferriphilum) were isolated and the assays were performed with individual bacteria and in combination with At. thiooxidans. In conclusion, it was found that the consortium integrated by At. ferrooxidans and At. thiooxidans removed 70% of copper in 35 days from the selected ore, showing significant differences with the other consortia, which removed only 35% of copper in 35 days. To validate the assays was done an escalation in columns, where the bacterial consortium achieved a higher percentage of copper extraction regarding to control. PMID:24294251

  5. Bacterial consortium for copper extraction from sulphide ore consisting mainly of chalcopyrite.

    PubMed

    Romo, E; Weinacker, D F; Zepeda, A B; Figueroa, C A; Chavez-Crooker, P; Farias, J G

    2013-01-01

    The mining industry is looking forward for bacterial consortia for economic extraction of copper from low-grade ores. The main objective was to determine an optimal bacterial consortium from several bacterial strains to obtain copper from the leach of chalcopyrite. The major native bacterial species involved in the bioleaching of sulphide ore (Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, Leptospirillum ferrooxidans and Leptospirillum ferriphilum) were isolated and the assays were performed with individual bacteria and in combination with At. thiooxidans. In conclusion, it was found that the consortium integrated by At. ferrooxidans and At. thiooxidans removed 70% of copper in 35 days from the selected ore, showing significant differences with the other consortia, which removed only 35% of copper in 35 days. To validate the assays was done an escalation in columns, where the bacterial consortium achieved a higher percentage of copper extraction regarding to control.

  6. Selective Inhibition of the Oxidation of Ferrous Iron or Sulfur in Thiobacillus ferrooxidans

    PubMed Central

    Harahuc, Lesia; Lizama, Hector M.; Suzuki, Isamu

    2000-01-01

    The oxidation of either ferrous iron or sulfur by Thiobacillus ferrooxidans was selectively inhibited or controlled by various anions, inhibitors, and osmotic pressure. Iron oxidation was more sensitive than sulfur oxidation to inhibition by chloride, phosphate, and nitrate at low concentrations (below 0.1 M) and also to inhibition by azide and cyanide. Sulfur oxidation was more sensitive than iron oxidation to the inhibitory effect of high osmotic pressure. These differences were evident not only between iron oxidation by iron-grown cells and sulfur oxidation by sulfur-grown cells but also between the iron and sulfur oxidation activities of the same iron-grown cells. Growth experiments with ferrous iron or sulfur as an oxidizable substrate confirmed the higher sensitivity of iron oxidation to inhibition by phosphate, chloride, azide, and cyanide. Sulfur oxidation was actually stimulated by 50 mM phosphate or chloride. Leaching of Fe and Zn from pyrite (FeS2) and sphalerite (ZnS) by T. ferrooxidans was differentially affected by phosphate and chloride, which inhibited the solubilization of Fe without significantly affecting the solubilization of Zn. PMID:10698768

  7. Effects of Arsenite Resistance on the Growth and Functional Gene Expression of Leptospirillum ferriphilum and Acidithiobacillus thiooxidans in Pure Culture and Coculture.

    PubMed

    Jiang, Huidan; Liang, Yili; Yin, Huaqun; Xiao, Yunhua; Guo, Xue; Xu, Ying; Hu, Qi; Liu, Hongwei; Liu, Xueduan

    2015-01-01

    The response of iron-oxidizing Leptospirillum ferriphilum YSK and sulfur-oxidizing Acidithiobacillus thiooxidans A01 to arsenite under pure culture and coculture was investigated based on biochemical characterization (concentration of iron ion and pH value) and related gene expression. L. ferriphilum YSK and At. thiooxidans A01 in pure culture could adapt up to 400 mM and 800 mM As(III) after domestication, respectively, although arsenite showed a negative effect on both strains. The coculture showed a stronger sulfur and ferrous ion oxidation activity when exposed to arsenite. In coculture, the pH value showed no significant difference when under 500 mM arsenite stress, and the cell number of At. thiooxidans was higher than that in pure culture benefiting from the interaction with L. ferriphilum. The expression profile showed that the arsenic efflux system in the coculture was more active than that in pure culture, indicating that there is a synergetic interaction between At. thiooxidans A01 and L. ferriphilum YSK. In addition, a model was proposed to illustrate the interaction between arsenite and the ars operon in L. ferriphilum YSK and At. thiooxidans A01. This study will facilitate the effective application of coculture in the bioleaching process by taking advantage of strain-strain communication and coordination.

  8. The mechanism of bacterial action in the leaching of pyrite by Thiobacillus ferrooxidans. An electrochemical study

    SciTech Connect

    Holmes, P.R.; Fowler, T.A.; Crundwell, F.K.

    1999-08-01

    In many of the experiments reported in the literature on the leaching of pyrite by Thiobacillus ferrooxidans, the concentrations of ferric and ferrous ions in the presence of bacteria differ significantly from experiments conducted in their absence. In addition, these concentrations change throughout the course of the experiment. This makes it difficult to determine whether the presence of bacteria increases the rate of leaching above that for chemical leaching at the same solution conditions. The authors have designed an experimental apparatus to overcome this problem. This apparatus controls the redox potential in one compartment of an electrolytic cell by manipulating the current to the cell. In this manner, the concentrations of ferrous and ferric ions are maintained at their initial values for the duration of the experiment. Two types of experiments are reported in this paper. In the first, pyrite electrodes were exposed to solutions of the same bulk conditions in the presence and absence of bacteria, and their mixed potentials were determined. In the second, particulate pyrite was leached with and without bacteria to determine the effect that bacteria have on the rate of leaching. The mixed potential of bacterially dissolved pyrite decreases as microcolonies and biofilms form on the surface of pyrite electrode over a 14 day period. On the other hand, the mixed potential of chemically dissolved pyrite is constant over the same period. The results of the leaching experiments show that Thiobacillus ferrooxidans enhances the rate of leaching above that found in the absence of bacteria at the same conditions in solution. An electrochemical model of pyrite dissolution is derived that describes the mixed potential and the kinetics of pyrite leaching. This analysis indicates that the decrease in mixed potential and the increase in the leaching rate in the presence of bacteria are due to an increase in the pH at the surface.

  9. RNA transcript sequencing reveals inorganic sulfur compound oxidation pathways in the acidophile Acidithiobacillus ferrivorans.

    PubMed

    Christel, Stephan; Fridlund, Jimmy; Buetti-Dinh, Antoine; Buck, Moritz; Watkin, Elizabeth L; Dopson, Mark

    2016-04-01

    Acidithiobacillus ferrivorans is an acidophile implicated in low-temperature biomining for the recovery of metals from sulfide minerals. Acidithiobacillus ferrivorans obtains its energy from the oxidation of inorganic sulfur compounds, and genes encoding several alternative pathways have been identified. Next-generation sequencing of At. ferrivorans RNA transcripts identified the genes coding for metabolic and electron transport proteins for energy conservation from tetrathionate as electron donor. RNA transcripts suggested that tetrathionate was hydrolyzed by the tetH1 gene product to form thiosulfate, elemental sulfur and sulfate. Despite two of the genes being truncated, RNA transcripts for the SoxXYZAB complex had higher levels than for thiosulfate quinone oxidoreductase (doxDAgenes). However, a lack of heme-binding sites in soxX suggested that DoxDA was responsible for thiosulfate metabolism. Higher RNA transcript counts also suggested that elemental sulfur was metabolized by heterodisulfide reductase (hdrgenes) rather than sulfur oxygenase reductase (sor). The sulfite produced as a product of heterodisulfide reductase was suggested to be oxidized by a pathway involving the sat gene product or abiotically react with elemental sulfur to form thiosulfate. Finally, several electron transport complexes were involved in energy conservation. This study has elucidated the previously unknown At. ferrivorans tetrathionate metabolic pathway that is important in biomining.

  10. Short communication: Adverse effect of surface-active reagents on the bioleaching of pyrite and chalcopyrite by Thiobacillus ferrooxidans.

    PubMed

    Huerta, G; Escobar, B; Rubio, J; Badilla-Ohlbaum, R

    1995-09-01

    Oxidation of Fe(II) iron and bioleaching of pyrite and chalcopyrite by Thiobacillus ferrooxidans was adversely affected by isopropylxanthate, a flotation agent, and by LIX 984, a solvent-extraction agent, each at ≤ 1 g/l. The reagents/l were adsorbed on the bacterial surface, decreasing the bacteria's development and preventing biooxidation. Both reagents inhibited the bioleaching of pyrite and LIX 984 also inhibited the bioleaching of chalcopyrite.

  11. Gene function analysis in environmental isolates: The nif regulon of the strict iron oxidizing bacterium Leptospirillum ferrooxidans

    PubMed Central

    Parro, Víctor; Moreno-Paz, Mercedes

    2003-01-01

    A random genomic library from an environmental isolate of the Gram-negative bacterium Leptospirillum ferrooxidans has been printed on a microarray. Gene expression analysis was carried out with total RNA extracted from L. ferrooxidans cultures in the presence or absence of ammonium as nitrogen source under aerobic conditions. Although practically nothing is known about the genome sequence of this bacterium, this approach allowed us the selection and sequencing of only those clones bearing genes that showed an altered expression pattern. By sequence comparison, we have identified most of the genes of nitrogen fixation regulon in L. ferrooxidans, like the nifHDKENX operon, encoding the structural components of Mo-Fe nitrogenase; nifSU-hesB-hscBA-fdx operon, for Fe-S cluster assembly; the amtB gene (ammonium transporter); modA (molybdenum ABC type transporter); some regulatory genes like ntrC, nifA (the specific activator of nif genes); or two glnB-like genes (encoding the PII regulatory protein). Our results show that shotgun DNA microarrays are very powerful tools to accomplish gene expression studies with environmental bacteria whose genome sequence is still unknown, avoiding the time and effort necessary for whole genome sequencing projects. PMID:12808145

  12. Evidence of biogenic corrosion of titanium after exposure to a continuous culture of thiobacillus ferrooxidans grown in thiosulfate medium

    SciTech Connect

    Horn, J M; Martin, S I; Masterson, B

    2000-12-07

    Experiments were undertaken to evaluate extreme conditions under which candidate materials intended for use in a proposed nuclear waste repository might be susceptible to corrosion by endogenous microorganisms. Thiobucillus ferrooxidans, a sulfur-oxidizing bacterium, was grown in continuous culture using thiosulfate as an energy source; thiosulfate is oxidized to sulfate as a metabolic endproduct by this organism. Culture conditions were optimized to produce a high-density, metabolically active culture throughout a period of long term incubation in the presence of Alloy 22 (a high nickel-based alloy) and Titanium grade 7 (Tigr7) material coupons. After seven months incubation under these conditions, material coupons were withdrawn and analyzed by high resolution microscopy and energy dispersive x-ray analyses. Alloy 22 coupons showed no detectable signs of corrosion. Tigr7, however, demonstrated distinct roughening of the coupon surface, and [presumably solubilized and precipitated] titanium was detected on Alloy 22 coupons incubated in the same T. ferrooxiduns culture vessel. Control coupons of these materials incubated in sterile thiosulfate medium did not demonstrate any signs of corrosion, thus showing that observed corrosive effects were due to the T. ferrooxidans metabolic activities. T. ferrooxidans intermediates of thiosulfate oxidation or sulfate may have caused the corrosive effects observed on Tigr7.

  13. [Tn5037-a Tn21-like mercury transposon, detected in Thiobacillus ferrooxidans].

    PubMed

    Kaliaeva, E S; Kholodiĭ, G Ia; Bass, I A; Gorlenko, Zh M; Iur'eva, O V; Nikiforov, V G

    2001-08-01

    The 6645-bp mercury resistance transposon of the chemolithotrophic bacterium Thiobacillus ferrooxidans was cloned and sequenced. This transposon, named Tn5037, belongs to the Tn21 branch of the Tn21 subgroup, many members of which have been isolated from clinical sources. Having the minimum set of the genes (merRTPA), the mercury resistance operon of Tn5037 is organized similarly to most of the Gram-negative bacteria mer operons and is closest to that of Thiobacillus 3.2. The operator-promoter region of the mer operon of Tn5037 also has the common (Tn21/Tn501-like) structure. However, its inverted, presumably MerR protein binding repeats in the operator/promoter element are two base pairs shorter than in Tn21/Tn501. In the merA region, this transposon shares 77.4, 79.1, 83.2 and 87.8% identical bases with Tn21, Tn501, T. ferrooxidance E-15, and Thiobacillus 3.2, respectively. No inducibility of the Tn5037 mer operon was detected in the in vivo experiments. The transposition system (terminal repeats plus gene tnpA) of Tn5037 was inactive in Escherichia coli K12, in contrast to its resolution system (res site plus gene tnpR). However, transposition of Tn5037 in this host was provided by the tnpA gene of Tn5036, a member of the Tn21 subgroup. Sequence analysis of the Tn5037 res site suggested its recombinant nature.

  14. Modeling and analysis of biooxidation of gold bearing pyrite-arsenopyrite concentrates by Thiobacillus ferrooxidans.

    PubMed

    Chandraprabha, M N; Modak, Jayant M; Natarajan, K A; Raichur, Ashok M

    2003-01-01

    The results of modeling the biooxidation of a mixed sulfidic concentrate by Thiobacillus ferrooxidans is reported here. A kinetic model, which accounts for the dissolution of sulfide matrix due to both bacterial attachment onto the mineral surface and indirect leaching, has been proposed. A comprehensive system approach is employed for modeling the complex biooxidation process by (a) the decomposition of the complete system into several subsystems, (b) modeling individual systems, and (c) integrating the subsystems model in a final system model. The model for subsystems was developed by writing mass balance equations for the different species involved. The bacterial balance accounts for its growth, both on solid substrate and in solution, and for the attachment to and detachment from the surface. The kinetic parameters of the model were determined by designing the experiments in such a manner that only one subsystem was operational. This model was tested in both laboratory scale batch and continuous biooxidation processes. The model predictions agreed with the experimental data reasonably well. A further analysis of the model was carried out to predict the conditions for efficient biooxidation. Studies on the effect of residence time and pulp density on steady-state behavior showed that there is a critical residence time and pulp density below which washout conditions occur. Operation at pulp densities lower than 5% and residence times lower than 72 h was found unfavorable for efficient leaching.

  15. Functional Characterization of the FoxE Iron Oxidoreductase from the Photoferrotroph Rhodobacter ferrooxidans SW2*

    PubMed Central

    Saraiva, Ivo H.; Newman, Dianne K.; Louro, Ricardo O.

    2012-01-01

    Photoferrotrophy is presumed to be an ancient type of photosynthetic metabolism in which bacteria use the reducing power of ferrous iron to drive carbon fixation. In this work the putative iron oxidoreductase of the photoferrotroph Rhodobacter ferrooxidans SW2 was cloned, purified, and characterized for the first time. This protein, FoxE, was characterized using spectroscopic, thermodynamic, and kinetic techniques. It is a c-type cytochrome that forms a trimer or tetramer in solution; the two hemes of each monomer are hexacoordinated by histidine and methionine. The hemes have positive reduction potentials that allow downhill electron transfer from many geochemically relevant ferrous iron forms to the photosynthetic reaction center. The reduction potentials of the hemes are different and are cross-assigned to fast and slow kinetic phases of ferrous iron oxidation in vitro. Lower reactivity was observed at high pH and may contribute to prevent ferric iron precipitation inside or at the surface of the cell. These results help fill in the molecular details of a metabolic process that likely contributed to the deposition of precambrian banded iron formations, globally important sedimentary rocks that are found on every continent today. PMID:22661703

  16. Occurrences at mineral-bacteria interface during oxidation of arsenopyrite by Thiobacillus ferrooxidans.

    PubMed

    Fernandez, M G; Mustin, C; de Donato, P; Barres, O; Marion, P; Berthelin, J

    1995-04-05

    The combination of an improved bacterial desorption method, scanning electron microscopy (SEM), diffuse reflectance and transmission infrared Fourier transform spectroscopy, and a desorption-leaching device like high-pressure liquid chromatography (HPLC) was used to analyze bacterial populations (adhering and free bacteria) and surface-oxidized phases (ferric arsenates and elemental sulfur) during the arsenopyrite biooxidation by Thiobacillus ferrooxidans. The bacterial distribution, the physicochemical composition of the leachate, the evolution of corrosion patterns, and the nature and amount of the surface-oxidized chemical species characterized different behavior for each step of arsenopyrite bioleaching. The first step is characterized by a slow but strong adhesion of bacteria to mineral surfaces, the appearance of a surface phase of elemental sulfur, the weak solubilization of Fe(II), As(III), and As(V), and the presence of the first corrosion patterns, which follow the fragility zones and the crystallographic orientation of mineral grains. After this short step, growth of the unattached bacteria begins, while ferrous ions in solution are oxidized by them. Ferric ions produced by the bacteria can oxidize the sulfide directly and are regenerated by Fe(II) bacterial oxidation. At this time, a bioleaching cycle takes place and a coarse surface phase of ferric arsenate (FeAsO(4) . xH(2)O where x approximately 2) and deep ovoid pores appear. At the end of the bioleaching cycle, the high concentration of Fe(III) and As(V) in solution promotes the precipitation of a second phase of amorphous ferric arsenate (FeAsO(4) . xH(2)O where x approximately 4) in the leachate. Then the biooxidation process ceases: The bacteria adhering to the mineral sufaces are coated by the ferric arsenates and the concentration of Fe(III) on the leachate is found to have decreased greatly. Both oxidation mechanisms (direct and indirect oxidation) have been stopped. (c) 1995 John Wiley

  17. Fractionation behavior of heavy metals in soil during bioleaching with Acidithiobacillus thiooxidans.

    PubMed

    Naresh Kumar, R; Nagendran, R

    2009-09-30

    The effects of bioleaching on the fractionation of soil heavy metals were investigated in this study. Bioleaching of heavy metals from contaminated soil was carried out in shake flask experiments. Acidophilic sulfur oxidizing bacteria Acidithiobacillus thiooxidans isolated from soil was used for bioleaching. Bioleaching resulted in removal of heavy metals at higher levels. Variations in the binding forms of heavy metals before, during and after bioleaching were evaluated. It was noticed that bioleaching affected the binding forms of all the heavy metals present in the soil. The major contaminant chromium bound mainly to the fractions of soil which are not very reactive (organic and residual fractions) also showed good removal efficiency. Bioleaching influenced the fractionation of metals in soil after treatment and most of the remnant heavy metals were bound either to residual fraction or to other not easily mobile fractions of soil. The results of this study indicated that the bioleaching process can be useful for efficient removal of heavy metals from soil. Further, the soil with remnant metals can be disposed off safely.

  18. Bioleaching of nickel from spent petroleum catalyst using Acidithiobacillus thiooxidans DSM- 11478.

    PubMed

    Sharma, Mohita; Bisht, Varsha; Singh, Bina; Jain, Pratiksha; Mandal, Ajoy K; Lal, Banwari; Sarma, Priyangshu M

    2015-06-01

    The present work deals with optimization of culture conditions and process parameters for bioleaching of spent petroleum catalyst collected from a petroleum refinery. The efficacy of Ni bioleaching from spent petroleum catalyst was determined using pure culture of Acidithiobacillus thiooxidans DSM- 11478. The culture conditions of pH, temperature and headspace volume to media volume ratio were optimized. EDX analysis was done to confirm the presence of Ni in the spent catalyst after roasting it to decoke its surface. The optimum temperature for A. thiooxidans DSM-11478 growth was found to be 32 degrees C. The enhanced recovery of nickel at very low pH was attributed to the higher acidic strength of sulfuric acid produced in the culture medium by the bacterium. During the bioleaching process, 89% of the Ni present in the catalyst waste could be successfully recovered in optimized conditions. This environment friendly bioleaching process proved efficient than the chemical method. Taking leads from the lab scale results, bioleaching in larger volumes (1, 5 and 10 L) was also performed to provide guidelines for taking up this technology for in situ industrial waste management.

  19. Influence of the sulfur species reactivity on biofilm conformation during pyrite colonization by Acidithiobacillus thiooxidans.

    PubMed

    Lara, René H; García-Meza, J Viridiana; Cruz, Roel; Valdez-Pérez, Donato; González, Ignacio

    2012-08-01

    Massive pyrite (FeS₂) electrodes were potentiostatically modified by means of variable oxidation pulse to induce formation of diverse surface sulfur species (S(n)²⁻, S⁰). The evolution of reactivity of the resulting surfaces considers transition from passive (e.g., Fe(1-x )S₂) to active sulfur species (e.g., Fe(1-x )S(2-y ), S⁰). Selected modified pyrite surfaces were incubated with cells of sulfur-oxidizing Acidithiobacillus thiooxidans for 24 h in a specific culture medium (pH 2). Abiotic control experiments were also performed to compare chemical and biological oxidation. After incubation, the attached cells density and their exopolysaccharides were analyzed by confocal laser scanning microscopy (CLMS) and atomic force microscopy (AFM) on bio-oxidized surfaces; additionally, S(n)²⁻/S⁰ speciation was carried out on bio-oxidized and abiotic pyrite surfaces using Raman spectroscopy. Our results indicate an important correlation between the evolution of S(n)²⁻/S⁰ surface species ratio and biofilm formation. Hence, pyrite surfaces with mainly passive-sulfur species were less colonized by A. thiooxidans as compared to surfaces with active sulfur species. These results provide knowledge that may contribute to establishing interfacial conditions that enhance or delay metal sulfide (MS) dissolution, as a function of the biofilm formed by sulfur-oxidizing bacteria.

  20. Inhibition of microbial concrete corrosion by Acidithiobacillus thiooxidans with functionalised zeolite-A coating.

    PubMed

    Haile, Tesfaalem; Nakhla, George

    2009-01-01

    The inhibition of the corrosive action of Acidithiobacillus thiooxidans on concrete specimens coated by functionalised zeolite-A containing 14% zinc and 5% silver by weight was studied. Uncoated concrete specimens, epoxy-coated concrete specimens (EP), and functionalised zeolite-A coated concrete specimens with epoxy to zeolite weight ratios of 3:1 (Z1), 2:2 (Z2) and 1:3 (Z3) were studied. Specimens were characterised by x-ray powder diffraction and field emission scanning electron microscopy for the identification of corrosion products and morphological changes. Biomass growth at the conclusion of the 32-day experiments was 4, 179 and 193 mg volatile suspended solids g(-1) sulphur for the uncoated, EP and Z1 specimens, whereas that of Z2 and Z3 were negligible. In the uncoated, EP and Z1 specimens, sulphate production rates were 0.83, 9.1 and 8.8 mM SO(4)(2-) day(-1) and the specific growth rates, mu, were 0.14, 0.57 and 0.47 day(-1), respectively. The corresponding values for Z2 and Z3 were negligible due to their bacterial inhibition characteristics.

  1. Bioleaching of ultramafic tailings by acidithiobacillus spp. for CO2 sequestration.

    PubMed

    Power, Ian M; Dipple, Gregory M; Southam, Gordon

    2010-01-01

    Bioleaching experiments using various acid-generating substances, i.e., metal sulfides and elemental sulfur, were conducted to demonstrate the accelerated dissolution of chrysotile tailings collected from an asbestos mine near Clinton Creek, Yukon, Canada. Columns, possessing an acid-generating substance colonized with Acidithiobacillus sp., produced leachates with magnesium concentrations that were an order of magnitude greater than mine site waters or control column leachates. In addition, chrysotile tailings were efficient at neutralizing acidity, which resulted in the immobilization of metals (Fe, Cu, Zn) associated with the metal sulfide mine tailings that were used to generate acid. This suggests that tailings from acid mine drainage environments may be utilized to enhance chrysotile dissolution without polluting "downstream" ecosystems. These results demonstrate that the addition of an acid-generating substance in conjunction with a microbial catalyst can significantly enhance the release of magnesium ions, which are then available for the precipitation of carbonate minerals. This process, as part of a carbon dioxide sequestration program, has implications for reducing net greenhouse gas emissions in the mining industry.

  2. Leaching of Zinc Sulfide by Thiobacillus ferrooxidans: Experiments with a Controlled Redox Potential Indicate No Direct Bacterial Mechanism

    PubMed Central

    Fowler, T. A.; Crundwell, F. K.

    1998-01-01

    The role of Thiobacillus ferrooxidans in bacterial leaching of mineral sulfides is controversial. Much of the controversy is due to the fact that the solution conditions, especially the concentrations of ferric and ferrous ions, change during experiments. The role of the bacteria would be more easily discernible if the concentrations of ferric and ferrous ions were maintained at set values throughout the experimental period. In this paper we report results obtained by using the constant redox potential apparatus described previously (P. I. Harvey and F. K. Crundwell, Appl. Environ. Microbiol. 63:2586–2592, 1997). This apparatus is designed to control the redox potential in the leaching compartment of an electrolytic cell by reduction or oxidation of dissolved iron. By controlling the redox potential the apparatus maintains the concentrations of ferrous and ferric ions at their initial values. Experiments were conducted in the presence of T. ferrooxidans and under sterile conditions. Analysis of the conversion of zinc sulfide in the absence of the bacteria and analysis of the conversion of zinc sulfate in the presence of the bacteria produced the same results. This indicates that the only role of the bacteria under the conditions used is regeneration of ferric ions in solution. In this work we found no evidence that there is a direct mechanism for bacterial leaching. PMID:9758769

  3. Specific binding of Thiobacillus ferrooxidans RbcR to the intergenic sequence between the rbc operon and the rbcR gene.

    PubMed Central

    Kusano, T; Sugawara, K

    1993-01-01

    The presence of two sets (rbcL1-rbcS1 and rbcL2-rbcS2) of rbc operons has been demonstrated in Thiobacillus ferrooxidans Fe1 (T. Kusano, T. Takeshima, C. Inoue, and K. Sugawara, J. Bacteriol. 173:7313-7323, 1991). A possible regulatory gene, rbcR, 930 bp long and possibly translated into a 309-amino-acid protein, was found upstream from the rbcL1 gene as a single copy. The gene is located divergently to rbcL1 with a 144-bp intergenic sequence. As in the cases of the Chromatium vinosum RbcR and Alcaligenes eutrophus CfxR, T. ferrooxidans RbcR is thought to be a new member of the LysR family, and these proteins share 46.5 and 42.8% identity, respectively. Gel mobility shift assays showed that T. ferrooxidans RbcR, produced in Escherichia coli, binds specifically to the intergenic sequence between rbcL1 and rbcR. Footprinting and site-directed mutagenesis experiments further demonstrated that RbcR binds to overlapping promoter elements of the rbcR and rbcL1 genes. The above data strongly support the participation of RbcR in regulation of the rbcL1-rbcS1 operon and the rbcR gene in T. ferrooxidans. Images PMID:8432695

  4. Microbial treatment of sulfur-contaminated industrial wastes.

    PubMed

    Gómez-Ramírez, Marlenne; Zarco-Tovar, Karina; Aburto, Jorge; de León, Roberto García; Rojas-Avelizapa, Norma G

    2014-01-01

    The present study evaluated the microbial removal of sulfur from a solid industrial waste in liquid culture under laboratory conditions. The study involved the use of two bacteria Acidithiobacillus ferrooxidans ATCC 53987 and Acidithiobacillus thiooxidans AZCT-M125-5 isolated from a Mexican soil. Experimentation for industrial waste biotreatment was done in liquid culture using 125-mL Erlenmeyer flasks containing 30 mL Starkey modified culture medium and incubated at 30°C during 7 days. The industrial waste was added at different pulp densities (8.25-100% w/v) corresponding to different sulfur contents from 0.7 to 8.63% (w/w). Sulfur-oxidizing activity of the strain AZCT-M125-5 produced 281 and 262 mg/g of sulfate and a sulfur removal of 60% and 45.7% when the pulp density was set at 8.25 and 16.5% (w/v), respectively. In comparison, the strain A. ferrooxidans ATCC 53987 showed a lower sulfur-oxidizing activity with a sulfate production of 25.6 and 12.7 mg/g and a sulfur removal of 6% and 2.5% at the same pulp densities, respectively. Microbial growth was limited by pulp densities higher than 25% (w/v) of industrial waste with minimal sulfur-oxidizing activity and sulfur removal. The rate of sulfur removal for Acidithiobacillus thioxidans AZCT-M125-5 and Acidithiobacillus ferrooxidans ATCC 53987 was 0.185 and 0.0159 mg S g(-1) h(-1) with a pulp density of 16.5% (w/v), respectively. This study demonstrated that Acidithiobacillus thiooxidans AZCT-M125-5 possesses a high sulfur-oxidizing activity, even at high sulfur concentration, which allows the treatment of hazardous materials.

  5. Analysis of iron- and sulfur-oxidizing bacteria in a treatment plant of acid rock drainage from a Japanese pyrite mine by use of ribulose-1, 5-bisphosphate carboxylase/oxygenase large-subunit gene.

    PubMed

    Kamimura, Kazuo; Okabayashi, Ai; Kikumoto, Mei; Manchur, Mohammed Abul; Wakai, Satoshi; Kanao, Tadayoshi

    2010-03-01

    Iron- and sulfur-oxidizing bacteria in a treatment plant of acid rock drainage (ARD) from a pyrite mine in Yanahara, Okayama prefecture, Japan, were analyzed using the gene (cbbL) encoding the large subunit of ribulose-1, 5-bisphosphate carboxylase/oxygenase (RubisCO). Analyses of partial sequences of cbbL genes from Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Acidithiobacillus caldus strains revealed the diversity in their cbbL gene sequences. In contrast to the presence of two copies of form I cbbL genes (cbbL1 and cbbL2) in A. ferrooxidans genome, A. thiooxidans and A. caldus had a single copy of form I cbbL gene in their genomes. A phylogenetic analysis based on deduced amino acid sequences from cbbL genes detected in the ARD treatment plant and their close relatives revealed that 89% of the total clones were affiliated with A. ferrooxidans. Clones loosely affiliated with the cbbL from A. thiooxidans NB1-3 or Thiobacillus denitrificans was also detected in the treatment plant. cbbL gene sequences of iron- or sulfur-oxidizing bacteria isolated from the ARD and the ARD treatment plant were not detected in the cbbL libraries from the treatment plant, suggesting the low frequencies of isolates in the samples.

  6. The Two-Component System RsrS-RsrR Regulates the Tetrathionate Intermediate Pathway for Thiosulfate Oxidation in Acidithiobacillus caldus

    PubMed Central

    Wang, Zhao-Bao; Li, Ya-Qing; Lin, Jian-Qun; Pang, Xin; Liu, Xiang-Mei; Liu, Bing-Qiang; Wang, Rui; Zhang, Cheng-Jia; Wu, Yan; Lin, Jian-Qiang; Chen, Lin-Xu

    2016-01-01

    Acidithiobacillus caldus (A. caldus) is a common bioleaching bacterium that possesses a sophisticated and highly efficient inorganic sulfur compound metabolism network. Thiosulfate, a central intermediate in the sulfur metabolism network of A. caldus and other sulfur-oxidizing microorganisms, can be metabolized via the tetrathionate intermediate (S4I) pathway catalyzed by thiosulfate:quinol oxidoreductase (Tqo or DoxDA) and tetrathionate hydrolase (TetH). In A. caldus, there is an additional two-component system called RsrS-RsrR. Since rsrS and rsrR are arranged as an operon with doxDA and tetH in the genome, we suggest that the regulation of the S4I pathway may occur via the RsrS-RsrR system. To examine the regulatory role of the two-component system RsrS-RsrR on the S4I pathway, ΔrsrR and ΔrsrS strains were constructed in A. caldus using a newly developed markerless gene knockout method. Transcriptional analysis of the tetH cluster in the wild type and mutant strains revealed positive regulation of the S4I pathway by the RsrS-RsrR system. A 19 bp inverted repeat sequence (IRS, AACACCTGTTACACCTGTT) located upstream of the tetH promoter was identified as the binding site for RsrR by using electrophoretic mobility shift assays (EMSAs) in vitro and promoter-probe vectors in vivo. In addition, ΔrsrR, and ΔrsrS strains cultivated in K2S4O6-medium exhibited significant growth differences when compared with the wild type. Transcriptional analysis indicated that the absence of rsrS or rsrR had different effects on the expression of genes involved in sulfur metabolism and signaling systems. Finally, a model of tetrathionate sensing by RsrS, signal transduction via RsrR, and transcriptional activation of tetH-doxDA was proposed to provide insights toward the understanding of sulfur metabolism in A. caldus. This study also provided a powerful genetic tool for studies in A. caldus. PMID:27857710

  7. Bioleaching of arsenic from highly contaminated mine tailings using Acidithiobacillus thiooxidans.

    PubMed

    Lee, Eunseong; Han, Yosep; Park, Jeonghyun; Hong, Jeongsik; Silva, Rene A; Kim, Seungkon; Kim, Hyunjung

    2015-01-01

    The behavior of arsenic (As) bioleaching from mine tailings containing high amount of As (ca. 34,000 mg/kg) was investigated using Acidithiobacillus thiooxidans to get an insight on the optimal conditions that would be applied to practical heap and/or tank bioleaching tests. Initial pH (1.8-2.2), temperature (25-40 °C), and solid concentration (0.5-4.0%) were employed as experimental parameters. Complementary characterization experiments (e.g., XRD, SEM-EDS, electrophoretic mobility, cell density, and sulfate production) were also carried out to better understand the mechanism of As bioleaching. The results showed that final As leaching efficiency was similar regardless of initial pH. However, greater initial As leaching rate was observed at initial pH 1.8 than other conditions, which could be attributed to greater initial cell attachment to mine tailings. Unlike the trend observed when varying the initial pH, the final As leaching efficiency varied with the changes in temperature and solid concentration. Specifically, As leaching efficiency tended to decrease with increasing temperature due to the decrease in the bacterial growth rate at higher temperature. Meanwhile, As leaching efficiency tended to increase with decreasing solid concentration. The results for jarosite contents in mine tailings residue after bioleaching revealed that much greater amount of the jarosite was formed during the bioleaching reaction at higher solid concentration, suggesting that the coverage of the surface of the mine tailings by jarosite and/or the co-precipitation of the leached As with jarosite could be a dominant factor reducing As leaching efficiency.

  8. Influence of the surface speciation on biofilm attachment to chalcopyrite by Acidithiobacillus thiooxidans.

    PubMed

    Lara, René H; García-Meza, J Viridiana; González, Ignacio; Cruz, Roel

    2013-03-01

    Surfaces of massive chalcopyrite (CuFeS2) electrodes were modified by applying variable oxidation potential pulses under growth media in order to induce the formation of different secondary phases (e.g., copper-rich polysulfides, S n(2-); elemental sulfur, S(0); and covellite, CuS). The evolution of reactivity (oxidation capacity) of the resulting chalcopyrite surfaces considers a transition from passive or inactive (containing CuS and S n(2-)) to active (containing increasing amounts of S(0)) phases. Modified surfaces were incubated with cells of sulfur-oxidizing bacteria (Acidithiobacillus thiooxidans) for 24 h in a specific culture medium (pH 2). Abiotic control experiments were also performed to compare chemical and biological oxidation. After incubation, the density of cells attached to chalcopyrite surfaces, the structure of the formed biofilm, and their exopolysaccharides and nucleic acids were analyzed by confocal laser scanning microscopy (CLSM) and scanning electron microscopy coupled to dispersive X-ray analysis (SEM-EDS). Additionally, CuS and S n(2-)/S(0) speciation, as well as secondary phase evolution, was carried out on biooxidized and abiotic chalcopyrite surfaces using Raman spectroscopy and SEM-EDS. Our results indicate that oxidized chalcopyrite surfaces initially containing inactive S n(2-) and S n(2-)/CuS phases were less colonized by A. thiooxidans as compared with surfaces containing active phases (mainly S(0)). Furthermore, it was observed that cells were partially covered by CuS and S(0) phases during biooxidation, especially at highly oxidized chalcopyrite surfaces, suggesting the innocuous effect of CuS phases during A. thiooxidans performance. These results may contribute to understanding the effect of the concomitant formation of refractory secondary phases (as CuS and inactive S n(2-)) during the biooxidation of chalcopyrite by sulfur-oxidizing microorganisms in bioleaching systems.

  9. Evolution of biofilms during the colonization process of pyrite by Acidithiobacillus thiooxidans.

    PubMed

    González, Dulce M; Lara, René H; Alvarado, Keila N; Valdez-Pérez, Donato; Navarro-Contreras, Hugo R; Cruz, Roel; García-Meza, Jessica Viridiana

    2012-01-01

    We have applied epifluorescence principles, atomic force microscopy, and Raman studies to the analysis of the colonization process of pyrite (FeS(2)) by sulfuroxidizing bacteria Acidithiobacillus thiooxidans after 1, 15, 24, and 72 h. For the stages examined, we present results comprising the evolution of biofilms, speciation of S (n) (2-) /S(0) species, adhesion forces of attached cells, production and secretion of extracellular polymeric substances (EPS), and its biochemical composition. After 1 h, highly dispersed attached cells in the surface of the mineral were observed. The results suggest initial non-covalent, weak interactions (e.g., van der Waal's, hydrophobic interactions), mediating an irreversible binding mechanism to electrooxidized massive pyrite electrode (eMPE), wherein the initial production of EPS by individual cells is determinant. The mineral surface reached its maximum cell cover between 15 to 24 h. Longer biooxidation times resulted in the progressive biofilm reduction on the mineral surface. Quantification of attached cell adhesion forces indicated a strong initial mechanism (8.4 nN), whereas subsequent stages of mineral colonization indicated stability of biofilms and of the adhesion force to an average of 4.2 nN. A variable EPS (polysaccharides, lipids, and proteins) secretion at all stages was found; thus, different architectural conformation of the biofilms was observed during 120 h. The main EPS produced were lipopolysaccharides which may increase the hydrophobicity of A. thiooxidans biofilms. The highest amount of lipopolysaccharides occurred between 15-72 h. In contrast with abiotic surfaces, the progressive depletion of S (n) (2-) /S(0) was observed on biotic eMPE surfaces, indicating consumption of surface sulfur species. All observations indicated a dynamic biooxidation mechanism of pyrite by A. thiooxidans, where the biofilms stability and composition seems to occur independently from surface sulfur species depletion.

  10. Construction of small plasmid vectors for use in genetic improvement of the extremely acidophilic Acidithiobacillus caldus.

    PubMed

    Meng, Jianzhou; Wang, Huiyan; Liu, Xiangmei; Lin, Jianqun; Pang, Xin; Lin, Jianqiang

    2013-10-01

    The genetic improvement of biomining bacteria including Acidithiobacillus caldus could facilitate the bioleaching process of sulfur-containing minerals. However, the available vectors for use in A. caldus are very scanty and limited to relatively large broad-host-range IncQ plasmids. In this study, a set of small, mobilizable plasmid vectors (pBBR1MCS-6, pMSD1 and pMSD2) were constructed based on plasmid pBBR1MCS-2, which does not belong to the IncQ, IncW, or IncP groups. The function of the tac promoter on 5.8-kb pMSD2 was determined by inserting a kanamycin-resistant reporter gene. The resulting recombinant pMSD2-Km was successfully transferred by conjugation into A. caldus MTH-04 with transfer frequency of 1.38±0.64×10(-5). The stability and plasmid copy number of pMSD2-Km in A. caldus MTH-04 were 75±2.7% and 5-6 copies per cell, respectively. By inserting an arsABC operon into pMSD2, an arsenic-resistant recombinant pMSD2-As was constructed and transferred into A. caldus MTH-04 by conjugation. The arsenic tolerance of A. caldus MTH-04 containing pMSD2-As was obviously increased up to 45mM of NaAsO2. These vectors could be applied in genetic improvement of A. caldus as well as other bioleaching bacteria.

  11. Changes in biofilm structure during the colonization of chalcopyrite by Acidithiobacillus thiooxidans.

    PubMed

    García-Meza, J V; Fernández, J J; Lara, R H; González, I

    2013-07-01

    Biofilms of Acidithiobacillus thiooxidans were grown on the surface of massive chalcopyrite electrodes (MCE) where different secondary sulfur phases were previously formed by potentiostatic oxidation of MCE at 0.780≤Ean≤0.965 V (electrooxidized MCE, eMCE). The formation of mainly S⁰ and minor amounts of CuS and Sn²⁻ were detected on eMCEs. The eMCEs were incubated with A. thiooxidans cells for 1, 12, 24, 48, and 120 h in order to temporally monitor changes in eMCE's secondary phases, biofilm structure, and extracellular polymeric substance (EPS) composition (lipids, proteins, and polysaccharides) using microscopic, spectroscopic, electrochemical, and biochemical techniques. The results show significant cell attachments with stratified biofilm structure since the first hour of incubation and EPS composition changes, the most important being production after 48-120 h when the highest amount of lipids and proteins were registered. During 120 h, periodic oxidation/formation of S⁰/Sn²⁻ was recorded on biooxidized eMCEs, until a stable CuS composition was formed. In contrast, no evidence of CuS formation was observed on the eMCEs of the abiotic control, confirming that CuS formation results from microbial activity. The surface transformation of eMCE induces a structural transformation of the biofilm, evolving directly to a multilayered biofilm with more hydrophobic EPS and proteins after 120 h. Our results suggest that A. thiooxidans responded to the spatial and temporal distribution and chemical reactivity of the Sn²⁻/S⁰/CuS phases throughout 120 h. These results suggested a strong correlation between surface speciation, hydrophobic domains in EPS, and biofilm organization during chalcopyrite biooxidation by A. thiooxidans.

  12. Degradation of inhibitory substances in sludge by Galactomyces sp. Z3 and the role of its extracellular polymeric substances in improving bioleaching.

    PubMed

    Zhou, Jun; Zheng, Guanyu; Wong, Jonathan W C; Zhou, Lixiang

    2013-03-01

    This study sought to elucidate the effect and mechanism of Galactomyces sp. Z3 in improving the bioleaching of heavy metals from sludge. Results showed that co-inoculation of Galactomyces sp. Z3 and two Acidithiobacillus strains (Acidithiobacillus ferrooxidans LX5 and Acidithiobacillus thiooxidans TS6) reduced the period required for sludge bioleaching by 4.5days compared to Acidithiobacillus alone. Further, removal efficiencies of Cu, Zn and oxidation rate of Fe(2+) and S(0) were higher in co-inoculation system than the Acidithiobacillus alone. Galactomyces sp. Z3 consumed the acetate, propionate, iso-butyrate, butyrate, and iso-valerate in sludge from the initial concentrations of 109.50, 28.80, 7.70, 34.30, and 18.40mg/L to 10.20, 0.61, 0.63, 19.40 and 1.30mg/L, respectively, after 12h in the co-inoculation system, significantly lower than the concentrations observed in the Acidithiobacillus alone. Meanwhile, the surfactant properties of the extracellular polymeric substances produced by the Galactomyces accelerated the rate of sulfur oxidization by A. thiooxidans.

  13. Bioinformatic Analyses of Unique (Orphan) Core Genes of the Genus Acidithiobacillus: Functional Inferences and Use As Molecular Probes for Genomic and Metagenomic/Transcriptomic Interrogation

    PubMed Central

    González, Carolina; Lazcano, Marcelo; Valdés, Jorge; Holmes, David S.

    2016-01-01

    Using phylogenomic and gene compositional analyses, five highly conserved gene families have been detected in the core genome of the phylogenetically coherent genus Acidithiobacillus of the class Acidithiobacillia. These core gene families are absent in the closest extant genus Thermithiobacillus tepidarius that subtends the Acidithiobacillus genus and roots the deepest in this class. The predicted proteins encoded by these core gene families are not detected by a BLAST search in the NCBI non-redundant database of more than 90 million proteins using a relaxed cut-off of 1.0e−5. None of the five families has a clear functional prediction. However, bioinformatic scrutiny, using pI prediction, motif/domain searches, cellular location predictions, genomic context analyses, and chromosome topology studies together with previously published transcriptomic and proteomic data, suggests that some may have functions associated with membrane remodeling during cell division perhaps in response to pH stress. Despite the high level of amino acid sequence conservation within each family, there is sufficient nucleotide variation of the respective genes to permit the use of the DNA sequences to distinguish different species of Acidithiobacillus, making them useful additions to the armamentarium of tools for phylogenetic analysis. Since the protein families are unique to the Acidithiobacillus genus, they can also be leveraged as probes to detect the genus in environmental metagenomes and metatranscriptomes, including industrial biomining operations, and acid mine drainage (AMD). PMID:28082953

  14. EFFECT OF PHOSPHATE ION AND 2,4-DINITROPHENOL ON THE ACTIVITY OF INTACT CELLS OF THIOBACILLUS FERROOXIDANS

    PubMed Central

    Beck, Jay V.; Shafia, Fred M.

    1964-01-01

    Beck, Jay V. (Brigham Young University, Provo, Utah), and Fred M. Shafia. Effect of phosphate ion and 2,4-dinitrophenol on the activity of cell suspensions of Thiobacillus ferrooxidans. J. Bacteriol. 88:850–857. 1964.—The rate of oxidation of ferrous salts or elemental sulfur by aged cell suspensions, phosphate-depleted cells, or 2,4-dinitrophenol (DNP)-treated cells of Thiobacillus ferrooxidans was increased by addition of orthophosphate salts. The effect was found to be transitory, with the rate gradually approaching that observed prior to phosphate ion addition. The total increased oxygen uptake was observed to be roughly proportional to the amount of phosphate salt added. The efficiency of CO2 fixation accompanying oxidation of ferrous salts was found to be about 1.7 μmoles of CO2 fixed per 100 μmoles of O2 absorbed, in contrast to a value of about 8.0 μmoles of CO2 fixed per 100 μmoles of O2 uptake during sulfur oxidation. The rate of oxidation did not affect the CO2 fixation efficiency. Whereas addition of phosphate salts to aged or phosphate-depleted cells increased slightly the already high efficiency of CO2 fixation, it did not affect the complete inhibition of CO2 fixation observed in the presence of 10-5m DNP. The results indicate that the phosphate ion is essential for oxidation of the ferrous ion, and that dinitrophenol and other so-called upcoupling agents interfere with phosphate metabolism. The latter may be a result of action at the site of assimilation of the ferrous ion or it may be an effect on the electron-transport system. In any event, it seems obvious that the phosphate ion is converted into a nonactive form in the presence of dinitrophenol-treated cells, because additional quantities of orthophosphate salts cause an immediate, marked restoration of oxidative activity. PMID:14219046

  15. Leaching of Zinc Sulfide by Thiobacillus ferrooxidans: Bacterial Oxidation of the Sulfur Product Layer Increases the Rate of Zinc Sulfide Dissolution at High Concentrations of Ferrous Ions

    PubMed Central

    Fowler, T. A.; Crundwell, F. K.

    1999-01-01

    This paper reports the results of leaching experiments conducted with and without Thiobacillus ferrooxidans at the same conditions in solution. The extent of leaching of ZnS with bacteria is significantly higher than that without bacteria at high concentrations of ferrous ions. A porous layer of elemental sulfur is present on the surfaces of the chemically leached particles, while no sulfur is present on the surfaces of the bacterially leached particles. The analysis of the data using the shrinking-core model shows that the chemical leaching of ZnS is limited by the diffusion of ferrous ions through the sulfur product layer at high concentrations of ferrous ions. The analysis of the data shows that diffusion through the product layer does not limit the rate of dissolution when bacteria are present. This suggests that the action of T. ferrooxidans in oxidizing the sulfur formed on the particle surface is to remove the barrier to diffusion by ferrous ions. PMID:10583978

  16. Development of an automated water toxicity biosensor using Thiobacillus ferrooxidans for monitoring cyanides in natural water for a water filtering plant.

    PubMed

    Okochi, Mina; Mima, Koji; Miyata, Maki; Shinozaki, Youhei; Haraguchi, Satoshi; Fujisawa, Minoru; Kaneko, Masao; Masukata, Tadashi; Matsunaga, Tadashi

    2004-09-30

    An on-line biosensor consisting of immobilized Thiobacillus ferrooxidans and an oxygen electrode was developed for automated monitoring of acute toxicity in water samples. T. ferrooxidans is an obligatory acidophilic, autotrophic bacterium and derives its energy by the oxidation of ferrous ion, elemental sulfur, and reduced sulfur compounds including metal sulfides. The assay is based on the monitoring of a current increase by addition of toxicoids, which is caused by the inhibition of bacterial respiration and decrease in oxygen consumption. Optimum cell number on the membrane was 5.0 x 10(8) cells. The steady-state current was obtained when concentration of FeSO4 was above 3.6 mM at pH 3. The sensor response of T. ferrooxidans immobilized membrane for 5.0 microM KCN was within an error of 10% for 30 membranes. A linear relationship was obtained at KCN concentration in the range of 0.5-3.0 microM in a flow-type monitoring system. Minimum detectable concentrations of KCN, Na2S, and NaN3 were 0.5, 1.2, and 0.07 microM, respectively. The monitoring system contained two biosensors and these sensors were cleaned with sulfuric acid (pH 1.5) twice a day. This treatment could remove fouling on microbial immobilized membrane by natural water and ferrous precipitation in the flow cell. This flow-type monitoring sensor was operated continuously for 5 months. Also, T. ferrooxidans immobilized membrane can be stored for one month at 4 degrees C when preserved with wet absorbent cotton under argon gas.

  17. [Leaching of copper ore of the Udokanskoe deposit at low temperatures by an association of acidophilic chemolithotrophic microorganisms].

    PubMed

    Kondrat'eva, T F; Pivovarova, T A; Krylova, L N; Melamud, V S; Adamov, E V; Karavaĭko, G I

    2011-01-01

    Pure cultures of indigenous microorganisms Acidithiobacillus ferrooxidans strain TFUd, Leptospirillum ferrooxidans strain LUd, and Sulfobacillus thermotolerans strain SUd have been isolated from the oxidation zone of sulfide copper ore of the Udokanskoe deposit. Regimes of bacterial-chemical leaching of ore have been studied over a temperature range from -10 to +20 degrees C. Effects of pH, temperature, and the presence of microorganisms on the extraction of copper have been shown. Bacterial leaching has been detected only at positive values of temperature, and has been much more active at +20 than at +4 degrees C. The process of leaching was more active when the ore contained more hydrophilic and oxidized minerals. The possibility of copper ore leaching of the Udokanskoe deposit using sulfuric acid with pH 0.4 at negative values of temperature and applying acidophilic chemolithotrophic microorganisms at positive values of temperature and low pH values was shown.

  18. The bioleaching potential of a bacterial consortium.

    PubMed

    Latorre, Mauricio; Cortés, María Paz; Travisany, Dante; Di Genova, Alex; Budinich, Marko; Reyes-Jara, Angélica; Hödar, Christian; González, Mauricio; Parada, Pilar; Bobadilla-Fazzini, Roberto A; Cambiazo, Verónica; Maass, Alejandro

    2016-10-01

    This work presents the molecular foundation of a consortium of five efficient bacteria strains isolated from copper mines currently used in state of the art industrial-scale biotechnology. The strains Acidithiobacillus thiooxidans Licanantay, Acidiphilium multivorum Yenapatur, Leptospirillum ferriphilum Pañiwe, Acidithiobacillus ferrooxidans Wenelen and Sulfobacillus thermosulfidooxidans Cutipay were selected for genome sequencing based on metal tolerance, oxidation activity and bioleaching of copper efficiency. An integrated model of metabolic pathways representing the bioleaching capability of this consortium was generated. Results revealed that greater efficiency in copper recovery may be explained by the higher functional potential of L. ferriphilum Pañiwe and At. thiooxidans Licanantay to oxidize iron and reduced inorganic sulfur compounds. The consortium had a greater capacity to resist copper, arsenic and chloride ion compared to previously described biomining strains. Specialization and particular components in these bacteria provided the consortium a greater ability to bioleach copper sulfide ores.

  19. Bioleaching of zinc and aluminium from industrial waste sludges by means of Thiobacillus ferrooxidans.

    PubMed

    Solisio, C; Lodi, A; Veglio, F

    2002-01-01

    Biological solubilisation of heavy metals contained in two different kinds of industrial wastes was performed in batches employing a strain of Thiobacillus ferroxidans. The wastes tested were: a dust coming from the iron-manganese alloy production in an electric furnace (sludge 1) and a sludge coming from a process treatment plant of aluminium anodic oxidation (sludge 2). The experimental results pointed out the ability of the used strain to maintain the environment, that initially has a pH about 8, at strongly acid conditions (pH 2.5-3.5), producing sulphuric acid that is the chemical agent responsible for the metals solubilisation. At wastes initial concentration of 1%, the percentage of solubilised metals was 76 and 78% for the wastes 1 and 2, respectively, but the lag phase was considerably longer for sludge 2 than for sludge 1, indicating a different affinity of microorganisms for the solid phase. Increasing the initial slurry concentration, the percentage of removed metal reached 72-73% for the sludge 1, while in case of sludge 2, the total amount of solubilized metal progressively decreased. Two kinetic models are proposed to describe the trends of metals solubilization curves.

  20. Effect of Heavy metals on the iron oxidizing ability of Thiobacillus ferrooxidans: Part 1, Effect of silver

    SciTech Connect

    De, G.C.; Pesic, B.

    1992-01-01

    The effect of silver ions on the iron oxidizing ability of Thiobacillus ferrooxidans was studied using electrochemical and other physics-chemical techniques. Electrochemical investigation was conducted using a method based on redox potential change. Experiments were performed by adding an aliquot of separately prepared concentrate of the bacteria into the solution of ferrous ion and monitoring the redox potential for at least one hour. Pyrite was used as the indicator electrode. Parameters examined were pH, microbial cell density, ferrous, ferric and silver ion concentration, temperature and preconditioning period of the bacteria with silver ions, etc. Results obtained demonstrate that the rate of ferrous ion oxidation is dependent on pH (optimum pH range is 1.5--2.0) and the substrate (i.e. Fe(II)) to microbial cell concentration ratio. The mechanism of the bacteria mediated oxidation of ferrous iron is remarkably sensitive to temperature changes. At the vicinity of the optimum temperature (i.e. 25[degree]C), the reaction is likely to be controlled by the diffusion of Fe (II) ions through the cell wall of the bacteria, whereas below the range 18--25[degree]C, reaction kinetics may be the rate controlling factor. In the presence of 10 mg/L silver, the reaction may be kinetically controlled over the temperature range 5.5--25[degree]C. Inhibition of microbial FE(II) oxidation in the presence of silver may take place via a mixed mechanism in which silver may bind with both the enzyme and the enzyme-substrate complex.

  1. Hydrogen sulfide oxidation in novel Horizontal-Flow Biofilm Reactors dominated by an Acidithiobacillus and a Thiobacillus species.

    PubMed

    Gerrity, S; Kennelly, C; Clifford, E; Collins, G

    2016-09-01

    Hydrogen Sulfide (H2S) is an odourous, highly toxic gas commonly encountered in various commercial and municipal sectors. Three novel, laboratory-scale, Horizontal-Flow Biofilm Reactors (HFBRs) were tested for the removal of H2S gas from air streams over a 178-day trial at 10°C. Removal rates of up to 15.1 g [H2S] m(-3) h(-1) were achieved, demonstrating the HFBRs as a feasible technology for the treatment of H2S-contaminated airstreams at low temperatures. Bio-oxidation of H2S in the reactors led to the production of H(+) and sulfate (SO(2-)4) ions, resulting in the acidification of the liquid phase. Reduced removal efficiency was observed at loading rates of 15.1 g [H2S] m(-3) h(-1). NaHCO3 addition to the liquid nutrient feed (synthetic wastewater (SWW)) resulted in improved H2S removal. Bacterial diversity, which was investigated by sequencing and fingerprinting 16S rRNA genes, was low, likely due to the harsh conditions prevailing in the systems. The HFBRs were dominated by two species from the genus Acidithiobacillus and Thiobacillus. Nonetheless, there were significant differences in microbial community structure between distinct HFBR zones due to the influence of alkalinity, pH and SO4 concentrations. Despite the low temperature, this study indicates HFBRs have an excellent potential to biologically treat H2S-contaminated airstreams.

  2. Kinetic Constant Variability in Bacterial Oxidation of Elemental Sulfur▿

    PubMed Central

    Pokorna, Blanka; Mandl, Martin; Borilova, Sarka; Ceskova, Pavla; Markova, Romana; Janiczek, Oldrich

    2007-01-01

    Wide ranges of growth yields on sulfur (from 2.4 × 1010 to 8.1 × 1011 cells g−1) and maximum sulfur oxidation rates (from 0.068 to 1.30 mmol liter−1 h−1) of an Acidithiobacillus ferrooxidans strain (CCM 4253) were observed in 73 batch cultures. No significant correlation between the constants was observed. Changes of the Michaelis constant for sulfur (from 0.46 to 15.5 mM) in resting cells were also noted. PMID:17449698

  3. Chemical and surface analysis during evolution of arsenopyrite oxidation by Acidithiobacillus thiooxidans in the presence and absence of supplementary arsenic.

    PubMed

    Ramírez-Aldaba, Hugo; Valles, O Paola; Vazquez-Arenas, Jorge; Rojas-Contreras, J Antonio; Valdez-Pérez, Donato; Ruiz-Baca, Estela; Meraz-Rodríguez, Mónica; Sosa-Rodríguez, Fabiola S; Rodríguez, Ángel G; Lara, René H

    2016-10-01

    Bioleaching of arsenopyrite presents a great interest due to recovery of valuable metals and environmental issues. The current study aims to evaluate the arsenopyrite oxidation by Acidithiobacillus thiooxidans during 240h at different time intervals, in the presence and absence of supplementary arsenic. Chemical and electrochemical characterizations are carried out using Raman, AFM, SEM-EDS, Cyclic Voltammetry, EIS, electrophoretic and adhesion forces to comprehensively assess the surface behavior and biooxidation mechanism of this mineral. These analyses evidence the formation of pyrite-like secondary phase on abiotic control surfaces, which contrast with the formation of pyrite (FeS2)-like, orpiment (As2S3)-like and elementary sulfur and polysulfide (Sn(2-)/S(0)) phases found on biooxidized surfaces. Voltammetric results indicate a significant alteration of arsenopyrite due to (bio)oxidation. Resistive processes determined with EIS are associated with chemical and electrochemical reactions mediated by (bio)oxidation, resulting in the transformation of arsenopyrite surface and biofilm direct attachment. Charge transfer resistance is increased when (bio)oxidation is performed in the presence of supplementary arsenic, in comparison with lowered abiotic control resistances obtained in its absence; reinforcing the idea that more stable surface products are generated when As(V) is in the system. Biofilm structure is mainly comprised of micro-colonies, progressively enclosed in secondary compounds. A more compact biofilm structure with enhanced formation of secondary compounds is identified in the presence of supplementary arsenic, whereby variable arsenopyrite reactivity is linked and attributed to these secondary compounds, including Sn(2-)/S(0), pyrite-like and orpiment-like phases.

  4. Insights on the structure and stability of Licanantase: a trimeric acid-stable coiled-coil lipoprotein from Acidithiobacillus thiooxidans.

    PubMed

    Abarca, Fernando; Gutierrez-Maldonado, Sebastian E; Parada, Pilar; Martinez, Patricio; Maass, Alejandro; Perez-Acle, Tomas

    2014-01-01

    Licanantase (Lic) is the major component of the secretome of Acidithiobacillus thiooxidans when grown in elemental sulphur. When used as an additive, Lic improves copper recovery from bioleaching processes. However, this recovery enhancement is not fully understood. In this context, our aim is to predict the 3D structure of Lic, to shed light on its structure-function relationships. Bioinformatics analyses on the amino acid sequence of Lic showed a great similarity with Lpp, an Escherichia coli Lipoprotein that can form stable trimers in solution. Lic and Lpp share the secretion motif, intracellular processing and alpha helix structure, as well as the distribution of hydrophobic residues in heptads forming a hydrophobic core, typical of coiled-coil structures. Cross-linking experiments showed the presence of Lic trimers, supporting our predictions. Taking the in vitro and in silico evidence as a whole, we propose that the most probable structure for Lic is a trimeric coiled-coil. According to this prediction, a suitable model for Lic was produced using the de novo algorithm "Rosetta Fold-and-Dock". To assess the structural stability of our model, Molecular Dynamics (MD) and Replica Exchange MD simulations were performed using the structure of Lpp and a 14-alanine Lpp mutant as controls, at both acidic and neutral pH. Our results suggest that Lic was the most stable structure among the studied proteins in both pH conditions. This increased stability can be explained by a higher number of both intermonomer hydrophobic contacts and hydrogen bonds, key elements for the stability of Lic's secondary and tertiary structure.

  5. Natural Strain

    NASA Technical Reports Server (NTRS)

    Freed, Alan D.

    1995-01-01

    The purpose of this paper is to present a consistent and thorough development of the strain and strain-rate measures affiliated with Hencky. Natural measures for strain and strain-rate, as I refer to them, are first expressed in terms of of the fundamental body-metric tensors of Lodge. These strain and strain-rate measures are mixed tensor fields. They are mapped from the body to space in both the Eulerian and Lagrangian configurations, and then transformed from general to Cartesian fields. There they are compared with the various strain and strain-rate measures found in the literature. A simple Cartesian description for Hencky strain-rate in the Lagrangian state is obtained.

  6. Influence of organics and silica on Fe(II) oxidation rates and cell-mineral aggregate formation by the green-sulfur Fe(II)-oxidizing bacterium Chlorobium ferrooxidans KoFox - Implications for Fe(II) oxidation in ancient oceans

    NASA Astrophysics Data System (ADS)

    Gauger, Tina; Byrne, James M.; Konhauser, Kurt O.; Obst, Martin; Crowe, Sean; Kappler, Andreas

    2016-06-01

    Most studies on microbial phototrophic Fe(II) oxidation (photoferrotrophy) have focused on purple bacteria, but recent evidence points to the importance of green-sulfur bacteria (GSB). Their recovery from modern ferruginous environments suggests that these photoferrotrophs can offer insights into how their ancient counterparts grew in Archean oceans at the time of banded iron formation (BIF) deposition. It is unknown, however, how Fe(II) oxidation rates, cell-mineral aggregate formation, and Fe-mineralogy vary under environmental conditions reminiscent of the geological past. To address this, we studied the Fe(II)-oxidizer Chlorobium ferrooxidans KoFox, a GSB living in co-culture with the heterotrophic Geospirillum strain KoFum. We investigated the mineralogy of Fe(III) metabolic products at low/high light intensity, and in the presence of dissolved silica and/or fumarate. Silica and fumarate influenced the crystallinity and particle size of the produced Fe(III) minerals. The presence of silica also enhanced Fe(II) oxidation rates, especially at high light intensities, potentially by lowering Fe(II)-toxicity to the cells. Electron microscopic imaging showed no encrustation of either KoFox or KoFum cells with Fe(III)-minerals, though weak associations were observed suggesting co-sedimentation of Fe(III) with at least some biomass via these aggregates, which could support diagenetic Fe(III)-reduction. Given that GSB are presumably one of the most ancient photosynthetic organisms, and pre-date cyanobacteria, our findings, on the one hand, strengthen arguments for photoferrotrophic activity as a likely mechanism for BIF deposition on a predominantly anoxic early Earth, but, on the other hand, also suggest that preservation of remnants of Fe(II)-oxidizing GSB as microfossils in the rock record is unlikely.

  7. Effect of Heavy metals on the iron oxidizing ability of Thiobacillus ferrooxidans: Part 1, Effect of silver. Technical progress report, July 1992--September 1992

    SciTech Connect

    De, G.C.; Pesic, B.

    1992-12-01

    The effect of silver ions on the iron oxidizing ability of Thiobacillus ferrooxidans was studied using electrochemical and other physics-chemical techniques. Electrochemical investigation was conducted using a method based on redox potential change. Experiments were performed by adding an aliquot of separately prepared concentrate of the bacteria into the solution of ferrous ion and monitoring the redox potential for at least one hour. Pyrite was used as the indicator electrode. Parameters examined were pH, microbial cell density, ferrous, ferric and silver ion concentration, temperature and preconditioning period of the bacteria with silver ions, etc. Results obtained demonstrate that the rate of ferrous ion oxidation is dependent on pH (optimum pH range is 1.5--2.0) and the substrate (i.e. Fe(II)) to microbial cell concentration ratio. The mechanism of the bacteria mediated oxidation of ferrous iron is remarkably sensitive to temperature changes. At the vicinity of the optimum temperature (i.e. 25{degree}C), the reaction is likely to be controlled by the diffusion of Fe (II) ions through the cell wall of the bacteria, whereas below the range 18--25{degree}C, reaction kinetics may be the rate controlling factor. In the presence of 10 mg/L silver, the reaction may be kinetically controlled over the temperature range 5.5--25{degree}C. Inhibition of microbial FE(II) oxidation in the presence of silver may take place via a mixed mechanism in which silver may bind with both the enzyme and the enzyme-substrate complex.

  8. Strain Gage

    NASA Technical Reports Server (NTRS)

    1995-01-01

    HITEC Corporation developed a strain gage application for DanteII, a mobile robot developed for NASA. The gage measured bending forces on the robot's legs and warned human controllers when acceptable forces were exceeded. HITEC further developed the technology for strain gage services in creating transducers out of "Indy" racing car suspension pushrods, NASCAR suspension components and components used in motion control.

  9. Assessment of the microbial community in a constructed wetland that receives acid coal mine drainage.

    PubMed

    Nicomrat, Duongruitai; Dick, Warren A; Tuovinen, Olli H

    2006-01-01

    Constructed wetlands are used to treat acid drainage from surface or underground coal mines. However, little is known about the microbial communities in the receiving wetland cells. The purpose of this work was to characterize the microbial population present in a wetland that was receiving acid coal mine drainage (AMD). Samples were collected from the oxic sediment zone of a constructed wetland cell in southeastern Ohio that was treating acid drainage from an underground coal mine seep. Samples comprised Fe(III) precipitates and were pretreated with ammonium oxalate to remove interfering iron, and the DNA was extracted and purified by agarose gel electrophoresis prior to amplification of portions of the 16S rRNA gene. Amplified products were separated by denaturing gradient gel electrophoresis and DNA from seven distinct bands was excised from the gel and sequenced. The sequences were matched to sequences in the GenBank bacterial 16S rDNA database. The DNA in two of the bands yielded matches with Acidithiobacillus ferrooxidans and the DNA in each of the remaining five bands was consistent with one of the following microorganisms: Acidithiobacillus thiooxidans, strain TRA3-20 (a eubacterium), strain BEN-4 (an arsenite-oxidizing bacterium), an Alcaligenes sp., and a Bordetella sp. Low bacterial diversity in these samples reflects the highly inorganic nature of the oxic sediment layer where high abundance of iron- and sulfur-oxidizing bacteria would be expected. The results we obtained by molecular methods supported our findings, obtained using culture methods, that the dominant microbial species in an acid receiving, oxic wetland are A. thiooxidans and A. ferrooxidans.

  10. Assessment of the microbial community in a constructed wetland that receives acid coal mine drainage

    SciTech Connect

    Nicomrat, D.; Dick, W.A.; Tuovinen, O.H.

    2006-01-15

    Constructed wetlands are used to treat acid drainage from surface or underground coal mines. However, little is known about the microbial communities in the receiving wetland cells. The purpose of this work was to characterize the microbial population present in a wetland that was receiving acid coal mine drainage (AMD). Samples were collected from the oxic sediment zone of a constructed wetland cell in southeastern Ohio that was treating acid drainage from an underground coal mine seep. Samples comprised Fe(Ill) precipitates and were pretreated with ammonium oxalate to remove interfering iron, and the DNA was extracted and purified by agarose gel electrophoresis prior to amplification of portions of the 16S rRNA gene. Amplified products were separated by denaturing gradient gel electrophoresis and DNA from seven distinct bands was excised from the gel and sequenced. The sequences were matched to sequences in the GenBank bacterial 16S rDNA database. The DNA in two of the bands yielded matches with Acidithiobacillus ferrooxidans and the DNA in each of the remaining five bands was consistent with one of the following microorganisms: Acidithiobacillus thiooxidans, strain TRA3-20 (a eubacterium), strain BEN-4 (an arsenite-oxidizing bacterium), an Alcaligenes sp., and a Bordetella sp. Low bacterial diversity in these samples reflects the highly inorganic nature of the oxic sediment layer where high abundance of iron- and sulfur-oxidizing bacteria would be expected. The results we obtained by molecular methods supported our findings, obtained using culture methods, that the dominant microbial species in an acid receiving, oxic wetland are A. thiooxidans and A. ferrooxidans.

  11. Model-based evaluation of ferrous iron oxidation by acidophilic bacteria in chemostat and biofilm airlift reactors.

    PubMed

    Ebrahimi, Sirous; Faraghi, Neda; Hosseini, Maryam

    2015-10-01

    This article presents a model-based evaluation of ferrous iron oxidation in chemostat and biofilm airlift reactors inoculated with a mixed culture of Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans bacteria. The competition between the two types of bacteria in the chemostat and in the biofilm airlift reactors together with the distribution of both bacteria along the biofilm thickness at different time sections has been studied. The bacterial distribution profiles along the biofilm in the airlift reactor at different time scales show that in the beginning A. ferrooxidans bacteria are dominant, but when the reactor operates for a long time the desirable L. ferrooxidans species outcompete A. ferrooxidans as a result of the low Fe(2+) and high Fe(3+) concentrations. The results obtained from the simulation were compared with the experimental data of continuously operated internal loop airlift biofilm reactor. The model results are in good agreement with the experimental results.

  12. High temperature strain gage apparent strain compensation

    NASA Technical Reports Server (NTRS)

    Holmes, Harlan K.; Moore, T. C., Sr.

    1992-01-01

    Once an installed strain gage is connected to a strain indicating device and the instrument is balanced, a subsequent change in temperature of the gage installation will generally produce a resistance change in the gage. This purely temperature-induced resistance will be registered by the indicating device as a strain and is referred to as 'apparent strain' to distinguish it from strain due to applied stress. One desirable technique for apparent strain compensation is to employ two identical gages with identical mounting procedures which are connected with a 'half bridge' configuration where gages see the same thermal environment but only one experiences a mechanical strain input. Their connection in adjacent arms of the bridge will then balance the thermally induced apparent strains and, in principle, only the mechanical strain remains. Two approaches that implement this technique are discussed.

  13. Geobacteraceae strains and methods

    DOEpatents

    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.

  14. Extracellular polymeric substances mediate bioleaching/biocorrosion via interfacial processes involving iron(III) ions and acidophilic bacteria.

    PubMed

    Sand, Wolfgang; Gehrke, Tilman

    2006-01-01

    Extracellular polymeric substances seem to play a pivotal role in biocorrosion of metals and bioleaching, biocorrosion of metal sulfides for the winning of precious metals as well as acid rock drainage. For better control of both processes, the structure and function of extracellular polymeric substances of corrosion-causing or leaching bacteria are of crucial importance. Our research focused on the extremophilic bacteria Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans, because of the "simplicity" and knowledge about the interactions of these bacteria with their substrate/substratum and their environment. For this purpose, the composition of the corresponding extracellular polymeric substances and their functions were analyzed. The extracellular polymeric substances of both species consist mainly of neutral sugars and lipids. The functions of the exopolymers seem to be: (i) to mediate attachment to a (metal) sulfide surface, and (ii) to concentrate iron(III) ions by complexation through uronic acids or other residues at the mineral surface, thus, allowing an oxidative attack on the sulfide. Consequently, dissolution of the metal sulfide is enhanced, which may result in an acceleration of 20- to 100-fold of the bioleaching process over chemical leaching. Experiments were performed to elucidate the importance of the iron(III) ions complexed by extracellular polymeric substances for strain-specific differences in oxidative activity for pyrite. Strains of A. ferrooxidans with a high amount of iron(III) ions in their extracellular polymeric substances possess greater oxidation activity than those with fewer iron(III) ions. These data provide insight into the function of and consequently the advantages that extracellular polymeric substances provide to bacteria. The role of extracellular polymeric substances for attachment under the conditions of a space station and resulting effects like biofouling, biocorrosion, malodorous gases, etc. will be discussed.

  15. Muscle strain treatment

    MedlinePlus

    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 ( ...

  16. Muscle strain (image)

    MedlinePlus

    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 ...

  17. Generation of acid mine drainage around the Karaerik copper mine (Espiye, Giresun, NE Turkey): implications from the bacterial population in the Acısu effluent.

    PubMed

    Sağlam, Emine Selva; Akçay, Miğraç; Çolak, Dilşat Nigar; İnan Bektaş, Kadriye; Beldüz, Ali Osman

    2016-09-01

    The Karaerik Cu mine is a worked-out deposit with large volumes of tailings and slags which were left around the mine site without any protection. Natural feeding of these material and run-off water from the mineralised zones into the Acısu effluent causes a serious environmental degradation and creation of acid mine drainage (AMD) along its entire length. This research aims at modelling the formation of AMD with a specific attempt on the characterisation of the bacterial population in association with AMD and their role on its occurrence. Based on 16SrRNA analyses of the clones obtained from a composite water sample, the bacterial community was determined to consist of Acidithiobacillus ferrivorans, Ferrovum myxofaciens, Leptospirillum ferrooxidans and Acidithiobacillus ferrooxidans as iron-oxidising bacteria, Acidocella facilis, Acidocella aluminiidurans, Acidiphilium cryptum and Acidiphilium multivorum as iron-reducing bacteria, and Acidithiobacillus ferrivorans, Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans and Acidiphilium cryptum as sulphur-oxidising bacteria. This association of bacteria with varying roles was interpreted as evidence of a concomitant occurrence of sulphur and iron cycles during the generation of AMD along the Acısu effluent draining the Karaerik mine.

  18. Insights to the effects of free cells on community structure of attached cells and chalcopyrite bioleaching during different stages.

    PubMed

    Feng, Shoushuai; Yang, Hailin; Wang, Wu

    2016-01-01

    The effects of free cells on community structure of attached cells and chalcopyrite bioleaching by Acidithiobacillus sp. during different stages were investigated. The attached cells of Acidithiobacillus thiooxidans owned the community advantage from 14thd to the end of bioprocess in the normal system. The community structure of attached cells was greatly influenced in the free cells-deficient systems. Compared to A. thiooxidans, the attached cells community of Acidithiobacillus ferrooxidans had a higher dependence on its free cells. Meanwhile, the analysis of key biochemical parameters revealed that the effects of free cells on chalcopyrite bioleaching in different stages were diverse, ranging from 32.8% to 64.3%. The bioleaching contribution of free cells of A. ferrooxidans in the stationary stage (8-14thd) was higher than those of A. thiooxidans, while the situation was gradually reversed in the jarosite passivation inhibited stage (26-40thd). These results may be useful in guiding chalcopyrite bioleaching.

  19. Superlattice strain gage

    DOEpatents

    Noel, B.W.; Smith, D.L.; Sinha, D.N.

    1988-06-28

    A strain gage comprising a strained-layer superlattice crystal exhibiting piezoelectric properties is described. A substrate upon which such a strained-layer superlattice crystal has been deposited is attached to an element to be monitored for strain. A light source is focused on the superlattice crystal and the light reflected from, passed through, or emitted from the crystal is gathered and compared with previously obtained optical property data to determine the strain in the element. 8 figs.

  20. Superlattice strain gage

    DOEpatents

    Noel, Bruce W.; Smith, Darryl L.; Sinha, Dipen N.

    1990-01-01

    A strain gage comprising a strained-layer superlattice crystal exhibiting piezoelectric properties is described. A substrate upon which such a strained-layer superlattice crystal has been deposited is attached to an element to be monitored for strain. A light source is focused on the superlattice crystal and the light reflected from, passed through, or emitted from the crystal is gathered and compared with previously obtained optical property data to determine the strain in the element.

  1. Comparative Genome Analysis Reveals Metabolic Versatility and Environmental Adaptations of Sulfobacillus thermosulfidooxidans Strain ST

    PubMed Central

    Guo, Xue; Yin, Huaqun; Liang, Yili; Hu, Qi; Zhou, Xishu; Xiao, Yunhua; Ma, Liyuan; Zhang, Xian; Qiu, Guanzhou; Liu, Xueduan

    2014-01-01

    The genus Sulfobacillus is a cohort of mildly thermophilic or thermotolerant acidophiles within the phylum Firmicutes and requires extremely acidic environments and hypersalinity for optimal growth. However, our understanding of them is still preliminary partly because few genome sequences are available. Here, the draft genome of Sulfobacillus thermosulfidooxidans strain ST was deciphered to obtain a comprehensive insight into the genetic content and to understand the cellular mechanisms necessary for its survival. Furthermore, the expressions of key genes related with iron and sulfur oxidation were verified by semi-quantitative RT-PCR analysis. The draft genome sequence of Sulfobacillus thermosulfidooxidans strain ST, which encodes 3225 predicted coding genes on a total length of 3,333,554 bp and a 48.35% G+C, revealed the high degree of heterogeneity with other Sulfobacillus species. The presence of numerous transposases, genomic islands and complete CRISPR/Cas defence systems testifies to its dynamic evolution consistent with the genome heterogeneity. As expected, S. thermosulfidooxidans encodes a suit of conserved enzymes required for the oxidation of inorganic sulfur compounds (ISCs). The model of sulfur oxidation in S. thermosulfidooxidans was proposed, which showed some different characteristics from the sulfur oxidation of Gram-negative A. ferrooxidans. Sulfur oxygenase reductase and heterodisulfide reductase were suggested to play important roles in the sulfur oxidation. Although the iron oxidation ability was observed, some key proteins cannot be identified in S. thermosulfidooxidans. Unexpectedly, a predicted sulfocyanin is proposed to transfer electrons in the iron oxidation. Furthermore, its carbon metabolism is rather flexible, can perform the transformation of pentose through the oxidative and non-oxidative pentose phosphate pathways and has the ability to take up small organic compounds. It encodes a multitude of heavy metal resistance systems to

  2. Comparative genome analysis reveals metabolic versatility and environmental adaptations of Sulfobacillus thermosulfidooxidans strain ST.

    PubMed

    Guo, Xue; Yin, Huaqun; Liang, Yili; Hu, Qi; Zhou, Xishu; Xiao, Yunhua; Ma, Liyuan; Zhang, Xian; Qiu, Guanzhou; Liu, Xueduan

    2014-01-01

    The genus Sulfobacillus is a cohort of mildly thermophilic or thermotolerant acidophiles within the phylum Firmicutes and requires extremely acidic environments and hypersalinity for optimal growth. However, our understanding of them is still preliminary partly because few genome sequences are available. Here, the draft genome of Sulfobacillus thermosulfidooxidans strain ST was deciphered to obtain a comprehensive insight into the genetic content and to understand the cellular mechanisms necessary for its survival. Furthermore, the expressions of key genes related with iron and sulfur oxidation were verified by semi-quantitative RT-PCR analysis. The draft genome sequence of Sulfobacillus thermosulfidooxidans strain ST, which encodes 3225 predicted coding genes on a total length of 3,333,554 bp and a 48.35% G+C, revealed the high degree of heterogeneity with other Sulfobacillus species. The presence of numerous transposases, genomic islands and complete CRISPR/Cas defence systems testifies to its dynamic evolution consistent with the genome heterogeneity. As expected, S. thermosulfidooxidans encodes a suit of conserved enzymes required for the oxidation of inorganic sulfur compounds (ISCs). The model of sulfur oxidation in S. thermosulfidooxidans was proposed, which showed some different characteristics from the sulfur oxidation of Gram-negative A. ferrooxidans. Sulfur oxygenase reductase and heterodisulfide reductase were suggested to play important roles in the sulfur oxidation. Although the iron oxidation ability was observed, some key proteins cannot be identified in S. thermosulfidooxidans. Unexpectedly, a predicted sulfocyanin is proposed to transfer electrons in the iron oxidation. Furthermore, its carbon metabolism is rather flexible, can perform the transformation of pentose through the oxidative and non-oxidative pentose phosphate pathways and has the ability to take up small organic compounds. It encodes a multitude of heavy metal resistance systems to

  3. Elevated temperature strain gages

    NASA Technical Reports Server (NTRS)

    Brittain, J. O.; Geslin, D.; Lei, J. F.

    1985-01-01

    Materials were evaluated that could be used in manufacturing electrical resistance strain gages for static strain measurements at temperatures at or above 1273 K. Strain gage materials must have a characteristic response to strain, temperature and time that is reproducible or that varies in a predictable manner within specified limits. Several metallic alloys were evaluated, as well as a series of transition metal carbides, nitrides and silicides.

  4. Sprains and Strains

    MedlinePlus

    ... happens. A strain is a stretched or torn muscle or tendon. Tendons are tissues that connect muscle to bone. Twisting or pulling these tissues can ... suddenly or develop over time. Back and hamstring muscle strains are common. Many people get strains playing ...

  5. Strain powered antennas

    NASA Astrophysics Data System (ADS)

    Domann, John P.; Carman, Greg P.

    2017-01-01

    This paper proposes the creation of strain powered antennas that radiate electromagnetic energy by mechanically vibrating a piezoelectric or piezomagnetic material. A closed form analytic model of electromagnetic radiation from a strain powered electrically small antenna is derived and analyzed. Fundamental scaling laws and the frequency dependence of strain powered antennas are discussed. The radiation efficiency of strain powered electrically small antennas is contrasted with a conventional electric dipole. Analytical results show that operating at the first mechanical resonance produces the most efficient strain powered radiation relative to electric dipole antennas. A resonant analysis is exploited to determine the material property space that produces efficient strain powered antennas. These results show how a properly designed strain powered antenna can radiate more efficiently than an equally sized electric dipole antenna.

  6. Three dimensional strained semiconductors

    DOEpatents

    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.

  7. Strain sensor comprising a strain sensitive, two-mode optical

    NASA Technical Reports Server (NTRS)

    Egalon, Claudio Oliveira (Inventor); Rogowski, Robert S. (Inventor)

    1994-01-01

    A strain sensor uses an optical fiber including a strain sensitive portion and at least one strain insensitive portion. The strain sensitive portion is mounted on the surface of a structure at a location where a strain is desired to be measured. The strain insensitive portion(s) may be fused to the strain sensitive portion to transmit light therethrough, so that the resulting pattern may be detected to determine the amount of strain by comparison with a similar fiber not subjected to strain, or with the light pattern produced when the fiber is not under strain.

  8. Thin film strain transducer

    NASA Technical Reports Server (NTRS)

    Rand, J. L. (Inventor)

    1984-01-01

    A strain transducer system and process for making the same is disclosed. A beryllium copper ring having four strain gages is electrically connected in Wheatstone bridge fashion to the output instrumentation. Tabs are bonded to a balloon or like surface with strain on the surface causing bending of a ring which provides an electrical signal through the gages proportional to the surface strain. A photographic pattern of a one half ring segment as placed on a sheet of beryllium copper for chem-mill etch formation is illustrated.

  9. Mechanical strain isolator mount

    NASA Technical Reports Server (NTRS)

    James, Gordon E. (Inventor)

    1991-01-01

    Certain devices such as optical instruments must preserve their alignmental integrity while being subjected to mechanical strain. A mechanical strain isolator mount is provided to preserve the alignmental integrity of an alignment sensitive instrument. An alignment sensitive instrument is mounted on a rectangular base. Flexural legs are connected at their proximal ends to the rectangular base. Flexural legs are also spaced parallel to the sides. Mounting pads are connected to the legs at the distal end and the mechanical strain isolator mount is attached to the substrate by means of threaded bolts. When a mounting pad and its respective leg is subjected to lateral strain in either the X or Y direction via the substrate, the respective leg relieves the strain by bending in the direction of the strain. An axial strain on a mounting pad in the Z direction is relieved by a rotational motion of the legs in the direction of the strain. When the substrate is stress free, the flexural legs return to their original condition and thus preserve the original alignment integrity of the alignment sensitive instrument.

  10. Light intensity strain analysis

    NASA Technical Reports Server (NTRS)

    Williams, J. G. (Inventor)

    1973-01-01

    A process is described for the analysis of the strain field of structures subjected to large deformations involving a low modulus substrate having a high modulus, relatively thin coating. The optical properties of transmittance and reflectance are measured for the coated substrate while stressed and unstressed to indicate the strain field for the coated substrate.

  11. Investigation of energy gene expressions and community structures of free and attached acidophilic bacteria in chalcopyrite bioleaching.

    PubMed

    Zhu, Jianyu; Jiao, Weifeng; Li, Qian; Liu, Xueduan; Qin, Wenqing; Qiu, Guanzhou; Hu, Yuehua; Chai, Liyuan

    2012-12-01

    In order to better understand the bioleaching mechanism, expression of genes involved in energy conservation and community structure of free and attached acidophilic bacteria in chalcopyrite bioleaching were investigated. Using quantitative real-time PCR, we studied the expression of genes involved in energy conservation in free and attached Acidithiobacillus ferrooxidans during bioleaching of chalcopyrite. Sulfur oxidation genes of attached A. ferrooxidans were up-regulated while ferrous iron oxidation genes were down-regulated compared with free A. ferrooxidans in the solution. The up-regulation may be induced by elemental sulfur on the mineral surface. This conclusion was supported by the results of HPLC analysis. Sulfur-oxidizing Acidithiobacillus thiooxidans and ferrous-oxidizing Leptospirillum ferrooxidans were the members of the mixed culture in chalcopyrite bioleaching. Study of the community structure of free and attached bacteria showed that A. thiooxidans dominated the attached bacteria while L. ferrooxidans dominated the free bacteria. With respect to available energy sources during bioleaching of chalcopyrite, sulfur-oxidizers tend to be on the mineral surfaces whereas ferrous iron-oxidizers tend to be suspended in the aqueous phase. Taken together, these results indicate that the main role of attached acidophilic bacteria was to oxidize elemental sulfur and dissolution of chalcopyrite involved chiefly an indirect bioleaching mechanism.

  12. Thin film strain transducer

    NASA Astrophysics Data System (ADS)

    Rand, J. L.

    1981-01-01

    Previous attempts to develop an appropriate sensor for measuring the stress or strain of high altitude balloons during flight are reviewed as well as the various conditions that must be met by such a device. The design, development and calibration of a transducer which promises to satisfy the necessary design constraints are described. The thin film strain transducer has a low effective modulus so as not to interfere with the strain that would naturally occur in the balloon. In addition, the transducer has a high sensitivity to longitudinal strain (7.216 mV/V/unit strain) which is constant for all temperature from room temperature to -80 C and all strains from 5 percent compression to 10 percent tensile strain. At the same time, the sensor is relatively insensitive (0.27 percent) to transverse forces. The device has a standard 350 ohm impedance which is compatible with available bridge balance, amplification and telemetry instrumentation now available for balloon flight. Recommendations are included for improved coatings to provide passive thermal control as well as model, tethered and full scale flight testing.

  13. Strain gauge installation tool

    DOEpatents

    Conard, Lisa Marie

    1998-01-01

    A tool and a method for attaching a strain gauge to a test specimen by maaining alignment of, and applying pressure to, the strain gauge during the bonding of the gauge to the specimen. The tool comprises rigid and compliant pads attached to a spring-loaded clamp. The pads are shaped to conform to the specimen surface to which the gauge is to be bonded. The shape of the pads permits the tool to align itself to the specimen and to maintain alignment of the gauge to the specimen during the bond curing process. A simplified method of attaching a strain gauge is provided by use of the tool.

  14. Leaching of Copper Ore by Thiobacillus Ferrooxidans.

    ERIC Educational Resources Information Center

    Lennox, John; Biaha, Thomas

    1991-01-01

    A quantitative laboratory exercise based upon the procedures copper manufacturers employ to increase copper production is described. The role of chemoautotrophic microorganisms in biogeologic process is emphasized. Safety considerations when working with bacteria are included. (KR)

  15. Electrochemistry of Thiobacillus ferrooxidans reactions with pyrite

    SciTech Connect

    Pesic, B.; Oliver, D.J.

    1990-01-01

    The objective of this project is to provide the fundamental information on the mechanisms of bacterial leaching of pyrite. The knowledge of how bacterial leaching of pyrite functions is essential for design and development of a technology for coal cleaning with bacteria. The features of major electrochemical techniques will be examined to find out if any of them can provide a diagnostic information on the mechanisms of related reactions. The research was focused on how to improve the chemical activity of bacteria. Two major approaches were undertaken. One was to provide more nutrient salts. It was anticipated that by providing higher amounts of nutrients the concentration and the activity of bacteria would increase. The other approach was to provide fresh environment to bacteria for the growth. Before the experiments it was decided to first examine their activity with time. However, there was no literature information available on this subject. The effect of the solution pH, was also studied. 4 refs., 8 figs.

  16. Electrochemistry of Thiobacillus ferrooxidans reactions with pyrite

    SciTech Connect

    Pesic, B.

    1992-01-01

    The objective of this project is to provide the fundamental information on the mechanisms of bacterial leaching of pyrite. The knowledge of how bacterial leaching of pyrite functions is essential for design and development of a technology for coal cleaning with bacteria. The features of major electrochemical techniques will be examined to find out if any of them can provide a diagnostic information on the mechanisms of related reactions.

  17. Sprains and Strains

    MedlinePlus

    ... Typically, people with a strain experience pain, limited motion, muscle spasms, and possibly muscle weakness. They also ... program designed to prevent stiffness, improve range of motion, and restore the joint's normal flexibility and strength. ...

  18. Strains and Sprains

    MedlinePlus

    ... in the joint or muscle swelling and bruising warmth and redness of the injured area difficulty moving ... looks "bent" or misshapen signs of infection (increased warmth, redness, streaks, swelling, and pain) a strain or ...

  19. Strain and magnetic remanence

    NASA Astrophysics Data System (ADS)

    Borradaile, Graham John

    1993-05-01

    Experimental data may be compatible with the hypothesis that a single direction of magnetic remanence rotates as a rigid marker with strains up to 40% shortening in coaxial, perfect flattening ( X = Y > Z). Detailed agreement with the passive line model is relatively poor for the specimens in which remanance is carried by magnetite. However, for this range of strains the differences with the passive line model (Wettstein's equation) are so slight that the latter model may be more easily employed to de-strain or restore deformed remanance to its original attitude. In the case of hematite-bearing remanences, the differences between the passive line and rigid marker model are even smaller because of the higher aspect ratios of grains of hematite. Therefore it is suggested that Wettstein's equation may be safely used to restore remanence after even higher strains, where the remanence is carried by hematite.

  20. Strain isolated ceramic coatings

    NASA Technical Reports Server (NTRS)

    Tolokan, R. P.; Brady, J. B.; Jarrabet, G. P.

    1985-01-01

    Plasma sprayed ceramic coatings are used in gas turbine engines to improve component temperature capability and cooling air efficiency. A compliant metal fiber strain isolator between a plasma sprayed ceramic coating and a metal substrate improves ceramic durability while allowing thicker coatings for better insulation. Development of strain isolated coatings has concentrated on design and fabrication of coatings and coating evaluation via thermal shock testing. In thermal shock testing, five types of failure are possible: buckling failure im compression on heat up, bimetal type failure, isothermal expansion mismatch failure, mudflat cracking during cool down, and long term fatigue. A primary failure mode for thermally cycled coatings is designated bimetal type failure. Bimetal failure is tensile failure in the ceramic near the ceramic-metal interface. One of the significant benefits of the strain isolator is an insulating layer protecting the metal substrate from heat deformation and thereby preventing bimetal type failure.

  1. Strain avalanches in plasticity

    NASA Astrophysics Data System (ADS)

    Argon, A. S.

    2013-09-01

    Plastic deformation at the mechanism level in all solids occurs in the form of discrete thermally activated individual stress relaxation events. While there are clear differences in mechanisms between dislocation mediated events in crystalline solids and by individual shear transformations in amorphous metals and semiconductors, such relaxation events interact strongly to form avalanches of strain bursts. In all cases the attendant distributions of released energy as amplitudes of acoustic emissions, or in serration amplitudes in flow stress, the levels of strain bursts are of fractal character with fractal exponents in the range from -1.5 to -2.0, having the character of phenomena of self-organized criticality, SOC. Here we examine strain avalanches in single crystals of ice, hcp metals, the jerky plastic deformations of nano-pillars of fcc and bcc metals deforming in compression, those in the plastic flow of bulk metallic glasses, all demonstrating the remarkable universality of character of plastic relaxation events.

  2. Strain gauge installation tool

    DOEpatents

    Conard, L.M.

    1998-06-16

    A tool and a method are disclosed for attaching a strain gauge to a test specimen by maintaining alignment of, and applying pressure to, the strain gauge during the bonding of the gauge to the specimen. The tool comprises rigid and compliant pads attached to a spring-loaded clamp. The pads are shaped to conform to the specimen surface to which the gauge is to be bonded. The shape of the pads permits the tool to align itself to the specimen and to maintain alignment of the gauge to the specimen during the bond curing process. A simplified method of attaching a strain gauge is provided by use of the tool. 6 figs.

  3. Radio frequency strain monitor

    NASA Technical Reports Server (NTRS)

    Heyman, Joseph S. (Inventor); Rogowski, Robert S. (Inventor); Holben, Jr., Milford S. (Inventor)

    1989-01-01

    A radio frequency strain monitor includes a voltage controlled oscillator for generating an oscillating signal that is input into a propagation path. The propagation path is preferably bonded to the surface of a structure to be monitored and produces a propagated signal. A phase difference between the oscillating and propagated signals is detected and maintained at a substantially constant value which is preferably a multiple of 90.degree. by changing the frequency of the oscillating signal. Any change in frequency of the oscillating signal provides an indication of strain in the structure to which the propagation path is bonded.

  4. Muscle strain injuries.

    PubMed

    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

  5. Spatial and Temporal Analysis of the Microbial Community in the Tailings of a Pb-Zn Mine Generating Acidic Drainage ▿ †

    PubMed Central

    Huang, Li-Nan; Zhou, Wen-Hua; Hallberg, Kevin B.; Wan, Cai-Yun; Li, Jie; Shu, Wen-Sheng

    2011-01-01

    Analysis of spatial and temporal variations in the microbial community in the abandoned tailings impoundment of a Pb-Zn mine revealed distinct microbial populations associated with the different oxidation stages of the tailings. Although Acidithiobacillus ferrooxidans and Leptospirillum spp. were consistently present in the acidic tailings, acidophilic archaea, mostly Ferroplasma acidiphilum, were predominant in the oxidized zones and the oxidation front, indicating their importance to generation of acid mine drainage. PMID:21705549

  6. Sadovskii vortex in strain

    NASA Astrophysics Data System (ADS)

    Freilich, Daniel; Llewellyn Smith, Stefan

    2015-11-01

    Sadovskii vortices are patches of fluid with uniform vorticity surrounded by a vortex sheet. They were first constructed as models for wakes behind bluff objects. We investigate the Sadovskii vortex in a straining field and examine limiting cases to validate our computational method. One limit is the patch vortex in strain (Moore & Saffman, Aircraft wake turbulence and its detection 1971), where there is no vortex sheet. We solve this as a free-boundary problem, and show that a simple method using the Biot-Savart law quickly gives solutions for stable shapes. When used for the more elongated (stronger straining field) situations, the method also leads to new vortex shapes. In the hollow vortex case, where there is no vortex patch and the circulation is entirely due to the vortex sheet (Llewellyn Smith and Crowdy, J. Fluid Mech. 691 2012), we use the Birkhoff-Rott equation to calculate the velocity of the fluid on the vortex boundary. The combination of these two methods can then be used to calculate the shape and velocity field of the Sadovksii vortex in strain.

  7. Strain gage barometric transmitter

    NASA Technical Reports Server (NTRS)

    Viton, P.

    1977-01-01

    A strain gage barometric transmitter for measuring the atmospheric pressure in severe environmental conditions is described. This equipment specifications are presented and its performance assessed. It is shown that this barometric sensor can measure the atmospheric pressure with a precision of 0.5 mb during a 6 month period.

  8. Hamstring strain - aftercare

    MedlinePlus

    ... not to push yourself too hard or too fast. A hamstring strain can recur, or your hamstring may tear. Talk to your provider before returning to work or any physical activity. Returning to normal activity too early can cause re-injury.

  9. Repetitive strain injury.

    PubMed

    Al-Otaibi, S T

    2001-05-01

    Repetitive strain injury is a group of musculoskeletal disorders affecting muscles, tendons, nerves and blood vessels. These disorders could be attributed to occupational causes; however non-occupational causes should be excluded. The management of these cases required a multidisciplinary team approach.

  10. Balloon film strain measurement

    NASA Astrophysics Data System (ADS)

    Rand, James L.

    In order to understand the state of stress in scientific balloons, a need exists for the measurement of film deformation in flight. The results of a flight test program are reported where material strain was measured for the first time during the inflation, launch, ascent and float of a typical natural shape, zero pressure scientific balloon.

  11. Microbiological and geochemical dynamics in simulated-heap leaching of a polymetallic sulfide ore.

    PubMed

    Wakeman, Kathryn; Auvinen, Hannele; Johnson, D Barrie

    2008-11-01

    The evolution of microbial populations involved in simulated-heap leaching of a polymetallic black schist sulfide ore (from the recently-commissioned Talvivaara mine, Finland) was monitored in aerated packed bed column reactors over a period of 40 weeks. The influence of ore particle size (2-6.5 mm and 6.5-12 mm) on changes in composition of the bioleaching microflora and mineral leaching dynamics in columns was investigated and compared to fine-grain (<2 microm) ore that was bioprocessed in shake flask cultures. Both column reactors and shake flasks were inoculated with 24 different species and strains of mineral-oxidizing and other acidophilic micro-organisms, and maintained at 37 degrees C. Mineral oxidation was most rapid in shake flask cultures, with about 80% of both manganese and nickel and 68% of zinc being leached within 6 weeks, though relatively little of the copper present in the ore was solubilised. The microbial consortium that emerged from the original inoculum was relatively simple in shake flasks, and was dominated by the iron-oxidizing autotroph Leptospirillum ferriphilum, with smaller numbers of Acidimicrobium ferrooxidans, Acidithiobacillus caldus and Leptospirillum ferrooxidans. Both metal recovery and (for the most part) total numbers of prokaryotes were greater in the column reactor containing the medium-grain than that containing the coarse-grain ore. The bioleaching communities in the columns displayed temporal changes in composition and differed radically from those in shake flask cultures. While iron-oxidizing chemoautotrophic bacteria were always the most numerically dominant bacteria in the medium-grain column bioreactor, there were major shifts in the most abundant species present, with the type strain of Acidithiobacillus ferrooxidans dominating in the early phase of the experiment and other bacteria (At. ferrooxidans NO37 and L. ferriphilum) dominating from week 4 to week 40. With the coarse-grain column bioreactor, similar

  12. Highly stretchable miniature strain sensor for large dynamic strain measurement

    DOE PAGES

    Song, Bo; Yao, Shurong; Nie, Xu; ...

    2016-01-01

    In this paper, a new type of highly stretchable strain sensor was developed to measure large strains. The sensor was based on the piezo-resistive response of carbon nanotube (CNT)/polydimethylsiloxane (PDMS) composite thin films. The piezo-resistive response of CNT composite gives accurate strain measurement with high frequency response, while the ultra-soft PDMS matrix provides high flexibility and ductility for large strain measurement. Experimental results show that the CNT/PDMS sensor measures large strains (up to 8 %) with an excellent linearity and a fast frequency response. The new miniature strain sensor also exhibits much higher sensitivities than the conventional foil strain gages,more » as its gauge factor is 500 times of that of the conventional foil strain gages.« less

  13. Highly stretchable miniature strain sensor for large dynamic strain measurement

    SciTech Connect

    Song, Bo; Yao, Shurong; Nie, Xu; Yu, Xun; Blecke, Jill

    2016-01-01

    In this paper, a new type of highly stretchable strain sensor was developed to measure large strains. The sensor was based on the piezo-resistive response of carbon nanotube (CNT)/polydimethylsiloxane (PDMS) composite thin films. The piezo-resistive response of CNT composite gives accurate strain measurement with high frequency response, while the ultra-soft PDMS matrix provides high flexibility and ductility for large strain measurement. Experimental results show that the CNT/PDMS sensor measures large strains (up to 8 %) with an excellent linearity and a fast frequency response. The new miniature strain sensor also exhibits much higher sensitivities than the conventional foil strain gages, as its gauge factor is 500 times of that of the conventional foil strain gages.

  14. Production of glycolic acid by chemolithotrophic iron- and sulfur-oxidizing bacteria and its role in delineating and sustaining acidophilic sulfide mineral-oxidizing consortia.

    PubMed

    Nancucheo, Ivan; Johnson, D Barrie

    2010-01-01

    Glycolic acid was detected as an exudate in actively growing cultures of three chemolithotrophic acidophiles that are important in biomining operations, Leptospirillum ferriphilum, Acidithiobacillus (At.) ferrooxidans, and At. caldus. Although similar concentrations of glycolic acid were found in all cases, the concentrations corresponded to ca. 24% of the total dissolved organic carbon (DOC) in cultures of L. ferriphilum but only ca. 5% of the total DOC in cultures of the two Acidithiobacillus spp. Rapid acidification (to pH 1.0) of the culture medium of At. caldus resulted in a large increase in the level of DOC, although the concentration of glycolic acid did not change in proportion. The archaeon Ferroplasma acidiphilum grew in the cell-free spent medium of At. caldus; glycolic acid was not metabolized, although other unidentified compounds in the DOC pool were metabolized. Glycolic acid exhibited levels of toxicity with 21 strains of acidophiles screened similar to those of acetic acid. The most sensitive species were chemolithotrophs (L. ferriphilum and At. ferrivorans), while the most tolerant species were chemoorganotrophs (Acidocella, Acidobacterium, and Ferroplasma species), and the ability to metabolize glycolic acid appeared to be restricted (among acidophiles) to Firmicutes (chiefly Sulfobacillus spp.). Results of this study help explain why Sulfobacillus spp. rather than other acidophiles are the main organic carbon-degrading bacteria in continuously fed stirred tanks used to bioprocess sulfide mineral concentrates and also why temporary cessation of pH control in these systems, resulting in rapid acidification, often results in a plume of the archaeon Ferroplasma.

  15. Strain patterns and strain accumulation along plate margins

    NASA Technical Reports Server (NTRS)

    Savage, J. C.

    1978-01-01

    Observations of strain accumulation along plate margins in Japan, New Zealand, and the United States indicate that: (1) a typical maximum rate of secular strain accumulation is on the order of 0.3 ppm/a, (2) a substantial part of the strain accumulation process can be attributed to slip at depth on the major plate boundary faults, and (3) some plastic deformation in a zone 100 km or more in width is apparently involved in the strain accumulation process.

  16. High temperature strain gages

    NASA Technical Reports Server (NTRS)

    Gregory, Otto J. (Inventor); You, Tao (Inventor)

    2011-01-01

    A ceramic strain gage based on reactively sputtered indium-tin-oxide (ITO) thin films is used to monitor the structural integrity of components employed in aerospace propulsion systems operating at temperatures in excess of 1500.degree. C. A scanning electron microscopy (SEM) of the thick ITO sensors reveals a partially sintered microstructure comprising a contiguous network of submicron ITO particles with well defined necks and isolated nanoporosity. Densification of the ITO particles was retarded during high temperature exposure with nitrogen thus stabilizing the nanoporosity. ITO strain sensors were prepared by reactive sputtering in various nitrogen/oxygen/argon partial pressures to incorporate more nitrogen into the films. Under these conditions, sintering and densification of the ITO particles containing these nitrogen rich grain boundaries was retarded and a contiguous network of nano-sized ITO particles was established.

  17. Bioleaching of ilmenite and basalt in the presence of iron-oxidizing and iron-scavenging bacteria

    NASA Astrophysics Data System (ADS)

    Navarrete, Jesica U.; Cappelle, Ian J.; Schnittker, Kimberlin; Borrok, David M.

    2013-04-01

    Bioleaching has been suggested as an alternative to traditional mining techniques in extraterrestrial environments because it does not require extensive infrastructure and bulky hardware. In situ bioleaching of silicate minerals, such as those found on the moon or Mars, has been proposed as a feasible alternative to traditional extraction techniques that require either extreme heat and/or substantial chemical treatment. In this study, we investigated the biotic and abiotic leaching of basaltic rocks (analogues to those found on the moon and Mars) and the mineral ilmenite (FeTiO3) in aqueous environments under acidic (pH ˜ 2.5) and circumneutral pH conditions. The biological leaching experiments were conducted using Acidithiobacillus ferrooxidans, an iron (Fe)-oxidizing bacteria, and Pseudomonas mendocina, an Fe-scavenging bacteria. We found that both strains were able to grow using the Fe(II) derived from the tested basaltic rocks and ilmenite. Although silica leaching rates were the same or slightly less in the bacterial systems with A. ferrooxidans than in the abiotic control systems, the extent of Fe, Al and Ti released (and re-precipitated in new solid phases) was actually greater in the biotic systems. This is likely because the Fe(II) leached from the basalt was immediately oxidized by A. ferrooxidans, and precipitated into Fe(III) phases which causes a change in the equilibrium of the system, i.e. Le Chatelier's principle. Iron(II) in the abiotic experiment was allowed to build up in solution which led to a decrease in its overall release rate. For example, the percentage of Fe, Al and Ti leached (dissolved + reactive mineral precipitates) from the Mars simulant in the A. ferrooxidans experimental system was 34, 41 and 13% of the total Fe, Al and Ti in the basalt, respectively, while the abiotic experimental system released totals of only 11, 25 and 2%. There was, however, no measurable difference in the amounts of Fe and Ti released from ilmenite in the

  18. Strained Ring Energetic Binders

    DTIC Science & Technology

    1993-08-27

    polyhomobenzvalene ( PHBV ). PHBV was not found to have the mechanical instability problems of PBV, but was still thermally unstable (Tonset - 660C, Tmax - 1090C...DISCUSSION 4 Polybenzvalene (PBV) 4 Polyhomobenzvalene ( PHBV ) 6 Chain-Transfer Studies 11 CONCLUSIONS 15 EXPERIMENTAL PROCEDURES 16 .F 4E 19 APPENDICES A...strained ring polymers similar to PBV are known. The investigation of one of these polymers, polyhomobenzvalene ( PHBV ), is also described in this report

  19. Strain Gage Signal Interpretation.

    DTIC Science & Technology

    1986-02-01

    blades and vanes in many engines have been collected, played back and examined. The engine types encompass GE’s stable of turbine engines from the small...aeromechanical engineer . 1.3 SUMMARY OF RESULTS Strain gage signals from vibrating rotor blades and vanes were collected, examined, classified, and generalized...turboprops, to turbojets and to the large high bypass turbofan engines . Test conditions include all the phases that are investigated

  20. Strain Measurement - Unidirectional.

    DTIC Science & Technology

    1983-04-20

    a ballpoint pen or a rounded piece of brass rod. If critical alignment is not necessary, gage lines may be located outside the immediate gage location...supplemented as needed by tabulated values. If the test design includes specification limits for the values, they should be included on the plots. Plots of...enough baseline before the event to allow estimation of the noise and stability. If the strain is to be correlated to specific events, the events should

  1. What Are Sprains and Strains?

    MedlinePlus

    ... 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 ...

  2. Strain balanced quantum posts

    SciTech Connect

    Alonso-Alvarez, D.; Alen, B.; Ripalda, J. M.; Llorens, J. M.; Taboada, A. G.; Briones, F.; Roldan, M. A.; Hernandez-Saz, J.; Hernandez-Maldonado, D.; Herrera, M.; Molina, S. I.

    2011-04-25

    Quantum posts are assembled by epitaxial growth of closely spaced quantum dot layers, modulating the composition of a semiconductor alloy, typically InGaAs. In contrast with most self-assembled nanostructures, the height of quantum posts can be controlled with nanometer precision, up to a maximum value limited by the accumulated stress due to the lattice mismatch. Here, we present a strain compensation technique based on the controlled incorporation of phosphorous, which substantially increases the maximum attainable quantum post height. The luminescence from the resulting nanostructures presents giant linear polarization anisotropy.

  3. Sadovskii vortex in strain

    NASA Astrophysics Data System (ADS)

    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.

  4. Repetitive strain injury.

    PubMed

    van Tulder, Maurits; Malmivaara, Antti; Koes, Bart

    2007-05-26

    Repetitive strain injury remains a controversial topic. The term repetitive strain injury includes specific disorders such as carpal tunnel syndrome, cubital tunnel syndrome, Guyon canal syndrome, lateral epicondylitis, and tendonitis of the wrist or hand. The diagnosis is usually made on the basis of history and clinical examination. Large high-quality studies using newer imaging techniques, such as MRI and ultrasonography are few. Consequently, the role of such imaging in diagnosis of upper limb disorders remains unclear. In many cases, no specific diagnosis can be established and complaints are labelled as non-specific. Little is known about the effectiveness of treatment options for upper limb disorders. Strong evidence for any intervention is scarce and the effect, if any, is mainly short-term pain relief. Exercise is beneficial for non-specific upper limb disorders. Immobilising hand braces and open carpal tunnel surgery release are beneficial for carpal tunnel syndrome, and topical and oral non-steroidal anti-inflammatory drugs, and corticosteroid injections are helpful for lateral epicondylitis. Exercise is probably beneficial for neck pain, as are corticosteroid injections and exercise for shoulder pain. Although upper limb disorders occur frequently in the working population, most trials have not exclusively included a working population or assessed effects on work-related outcomes. Further high-quality trials should aim to include sufficient sample sizes, working populations, and work-related outcomes.

  5. Strain Pattern in Supercooled Liquids

    NASA Astrophysics Data System (ADS)

    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.

  6. Hydrogen production from microbial strains

    DOEpatents

    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.

  7. Flagella and pili of iron-oxidizing thiobacilli isolated from a uranium mine in northern Ontario, Canada

    SciTech Connect

    DiSpirito, A.A.; Silver, M.; Voss, L.; Tuovinen, O.H.

    1982-05-01

    Five strains of Thiobacillus ferrooxidans, which included three recent isolates from a uranium mine, possessed flagella. Three of the strains had several pili per cell. The dimensions, fine structure, and orientation of the flagella were different. Both polar and peritrichous flagella were observed, indicating strain-dependent ultrastructural variation in acidophilic thiobacilli. Neither flagella nor pili were detected in eight other strains of T. ferrooxidans and two strains of Thiobacillus acidophilus by electron microscopy, although all of the cultures contained motile cells.

  8. Strain relaxation in nanopatterned strained silicon round pillars

    NASA Astrophysics Data System (ADS)

    Himcinschi, C.; Singh, R.; Radu, I.; Milenin, A. P.; Erfurth, W.; Reiche, M.; Gösele, U.; Christiansen, S. H.; Muster, F.; Petzold, M.

    2007-01-01

    Periodic arrays of strained Si (sSi) round nanopillars were fabricated on sSi layers deposited on SiGe virtual substrates by electron-beam lithography and subsequent reactive-ion etching. The strain in the patterned sSi nanopillars was determined using high-resolution UV micro-Raman spectroscopy. The strain relaxes significantly upon nanostructuring: from 0.9% in the unpatterned sSi layer to values between 0.22% and 0.57% in the round sSi pillars with diameters from 100 up to 500nm. The strain distribution in the sSi nanopillars was analyzed by finite element (FE) modeling. The FE calculations confirm the strain relaxation after patterning, in agreement with the results obtained from Raman spectroscopy.

  9. Adaptor for Measuring Principal Strains with Tuckerman Strain Gage

    NASA Technical Reports Server (NTRS)

    Mcpherson, A E

    1943-01-01

    An adapter is described which uses three Tuckerman optical strain gages to measure the displacement of the three vortices of an equilateral triangle along lines 120 degrees apart. These displacements are substituted in well-known equations in order to compute the magnitude and direction of the principal strains. Tests of the adaptor indicate that principal strains over a gage length of 1.42 inch may be measured with a systematic error not exceeding 4 percent and a mean observational error of the order of + or minus 0.000006. The maximum observed error in strain was of the order of 0.00006. The directions of principal strains for unidirectional stress were measured with the adaptor with an average error of the order of 1 degree.

  10. Strained graphene Hall bar

    NASA Astrophysics Data System (ADS)

    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.

  11. Biomechanical strain of goldsmiths.

    PubMed

    Cândido, Paula Emanuela Fernandes; Teixeira, Juliana Vieira Schmidt; Moro, Antônio Renato Pereira; Gontijo, Leila Amaral

    2012-01-01

    The work of the goldsmiths consists in the manufacture of jewelry. The piece, be it an earring, bracelet or necklace, is hand-assembled. This task requires precision, skill, kindness and patience. In this work, we make use of tools such as cuticle clippers and rounded tip, beads or precious stones and also pieces of metal. This type of activity requires a biomechanical stress of hands and wrists. In order to quantify the biomechanical stress, we performed a case study to measure the movements performed by an assembly of pieces of jewelry. As method for research, filming was done during assembly of parts to a paste, using a Nikon digital camera, for 1 (one) hour. The film was edited by Kinovea software, and the task was divided into cycles, each cycle corresponds to a complete object. In one cycle, there are four two movements of supination and pronation movements of the forearm. The cycle lasts approximately sixteen seconds, totaling 1800 cycles in eight hours. Despite the effort required of the wrists, the activity shows no complaints from the employees, but this fact does not mischaracterizes the ability of employees to acquire repetitive strain injuries and work-related musculoskeletal disorders.

  12. Characterization of Salmonella enteritidis strains.

    PubMed Central

    Poppe, C; McFadden, K A; Brouwer, A M; Demczuk, W

    1993-01-01

    A study was conducted to characterize 318 Salmonella enteritidis strains that were mainly isolated from poultry and their environment in Canada. Biotype, phagetype (PT), plasmid profile (PP), hybridization with a plasmid-derived virulence sequence probe, antibiotic resistance, outer membrane proteins (OMPs), and lipopolysaccharide (LPS) profiles were determined. Relationships of these properties to one another, and their diagnostic and pathogenic significance were assessed. Biotyping indicated that failure to ferment rhamnose was sometimes useful as a marker for epidemiologically related strains. Phagetyping was the most effective method for subdividing S. enteritidis; it distinguished 12 PTs. Phagetype 13 was occasionally associated with septicemia and mortality in chickens. The strains belonged to 15 PPs. A 36 megadalton (MDa) plasmid was found in 97% of the strains. Only the 36 MDa plasmid hybridized with the probe. Seventeen percent of the strains were drug resistant; all strains were sensitive to ciprofloxacin. Thirty-five of 36 strains possessed the same OMP profile, and 36 of 41 strains contained smooth LPS. Images Fig. 1. PMID:8358678

  13. Difference Between Strain and Sprain.

    ERIC Educational Resources Information Center

    Connors, G. Patrick

    Provided in this description of the differences between a strain (damage to the muscle or tendon) and a sprain (damage to the ligament) are definitions of mild, moderate, and severe (first, second, and third degree) strains and sprains. A final caution is given that these are two separate and distinct problems and should be treated as such. (DC)

  14. Hypothetical strain-free oligoradicals

    PubMed Central

    Hoffmann, Roald; Eisenstein, Odile; Balaban, Alexandru T.

    1980-01-01

    Several new classes of oligoradicals free of angle strain are suggested and examined by means of molecular orbital calculations. The collapse products of these hypothetical radicals are highly strained molecules. Various electronic strategies for the stabilization of these oligoradicals have been explored. PMID:16592882

  15. Strain gage system evaluation program

    NASA Technical Reports Server (NTRS)

    Dolleris, G. W.; Mazur, H. J.; Kokoszka, E., Jr.

    1978-01-01

    A program was conducted to determine the reliability of various strain gage systems when applied to rotating compressor blades in an aircraft gas turbine engine. A survey of current technology strain gage systems was conducted to provide a basis for selecting candidate systems for evaluation. Testing and evaluation was conducted in an F 100 engine. Sixty strain gage systems of seven different designs were installed on the first and third stages of an F 100 engine fan. Nineteen strain gage failures occurred during 62 hours of engine operation, for a survival rate of 68 percent. Of the failures, 16 occurred at blade-to-disk leadwire jumps (84 percent), two at a leadwire splice (11 percent), and one at a gage splice (5 percent). Effects of erosion, temperature, G-loading, and stress levels are discussed. Results of a post-test analysis of the individual components of each strain gage system are presented.

  16. Strain Insensitive Optical Phase Locked Loop

    NASA Technical Reports Server (NTRS)

    Egalon, Claudio O. (Inventor); Rogowski, Robert S. (Inventor)

    1998-01-01

    A strain sensor uses optical fibers including strain insensitive portions and a strain sensitive portion. The optical fibers form a sensitive arm of an optical phase locked loop (OPLL). The use of the OPLL allows for multimode optical fiber to be used in a strain insensitive configuration. Only strain information for the strain sensitive portion is monitored rather than the integrated strain measurements commonly made with optical fiber sensors.

  17. High temperature strain measurement with a resistance strain gage

    NASA Technical Reports Server (NTRS)

    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.

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

    PubMed Central

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

    2016-01-01

    Deformation imaging by echocardiography is a well-established research tool which has been gaining interest from clinical cardiologists since the introduction of speckle tracking. Post-processing of echo images to analyze deformation has become readily available at the fingertips of the user. New parameters such as global longitudinal strain have been shown to provide added diagnostic value, and ongoing efforts of the imaging societies and industry aimed at harmonizing methods will improve the technique further. This review focuses on recent advances in the field of echocardiographic strain and strain rate imaging, and provides an overview on its current and potential future clinical applications. PMID:27158476

  19. Molecular Characterization of Bacterial Respiration on Minerals

    SciTech Connect

    Blake, Robert C.

    2013-04-26

    The overall aim of this project was to contribute to our fundamental understanding of proteins and biological processes under extreme environmental conditions. We sought to define the biochemical and physiological mechanisms that underlie biodegradative and other cellular processes in normal, extreme, and engineered environments. Toward that end, we sought to understand the substrate oxidation pathways, the electron transport mechanisms, and the modes of energy conservation employed during respiration by bacteria on soluble iron and insoluble sulfide minerals. In accordance with these general aims, the specific aims were two-fold: To identify, separate, and characterize the extracellular biomolecules necessary for aerobic respiration on iron under strongly acidic conditions; and to elucidate the molecular principles whereby these bacteria recognize and adhere to their insoluble mineral substrates under harsh environmental conditions. The results of these studies were described in a total of nineteen manuscripts. Highlights include the following: 1. The complete genome of Acidithiobacillus ferrooxidans ATCC 23270 (type strain) was sequenced in collaboration with the DOE Joint Genome Institute; 2. Genomic and mass spectrometry-based proteomic methods were used to evaluate gene expression and in situ microbial activity in a low-complexity natural acid mine drainage microbial biofilm community. This was the first effort to successfully analyze a natural community using these techniques; 3. Detailed functional and structural studies were conducted on rusticyanin, an acid-stable electron transfer protein purified from cell-free extracts of At. ferrooxidans. The three-dimensional structure of reduced rusticyanin was determined from a combination of homonuclear proton and heteronuclear 15N- and 13C-edited NMR spectra. Concomitantly, the three-dimensional structure of oxidized rusticyanin was determined by X-ray crystallography to a resolution of 1.9 A by multiwavelength

  20. Low TCR nanocomposite strain gages

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  1. Virtual strain gage size study

    SciTech Connect

    Reu, Phillip L.

    2015-09-22

    DIC is a non-linear low-pass spatial filtering operation; whether we consider the effect of the subset and shape function, the strain window used in the strain calculation, of other post-processing of the results, each decision will impact the spatial resolution, of the measurement. More fundamentally, the speckle size limits, the spatial resolution by dictating the smallest possible subset. After this decision the processing settings are controlled by the allowable noise level balanced by possible bias errors created by the data filtering. This article describes a process to determine optimum DIC software settings to determine if the peak displacements or strains are being found.

  2. Radio Frequency (RF) strain monitor

    NASA Technical Reports Server (NTRS)

    Heyman, Joseph S. (Inventor); Rogowski, Robert S. (Inventor); Holben, Milford S., Jr. (Inventor)

    1988-01-01

    This invention relates to an apparatus for measuring strain in a structure. In particular, the invention detects strain in parts per million to over ten percent along an entire length (or other dimension) of a structure measuring a few millimeters to several kilometers. By using a propagation path bonded to the structure, the invention is not limited by the signal attenuation characteristics of the structure and thus frequencies in the megahertz to gigahertz range may be used to detect strain in part per million to over ten percent with high precision.

  3. Strain accumulation in quasicrystalline solids

    NASA Technical Reports Server (NTRS)

    Nori, Franco; Ronchetti, Marco; Elser, Veit

    1988-01-01

    The relaxation of two-dimensional quasicrystalline elastic networks when their constituent bonds are perturbed homogeneously is studied. Whereas ideal, quasi-periodic networks are stable against such perturbations, significant accumulations of strain in a class of disordered networks generated by a growth process are found. The grown networks are characterized by root mean square phason fluctuations which grow linearly with system size. The strain accumulation observed in these networks also grows linearly with system size. Finally, dependence of strain accumulation on cooling rate is found.

  4. PLASTICITY AND NON-LINEAR ELASTIC STRAINS

    DTIC Science & Technology

    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)

  5. Magnetic Domain Strain Sensor Program

    DTIC Science & Technology

    1990-08-01

    static strain measurement at elevated temperatures. 2.2 Magnetic Strain Measurement Theory The initial work at GED investigated the Barkhausen effect...including large and small Barkhausen jumps. This is a wave propaga- tion phenomenon in which a magnetic wave velocity is measured. The wave velocity in a...theory explaining the phenomenon that deviates from the Barkhausen effect. Some basic concepts had to be examined to better understand magnetic phenomena

  6. HIGH-TEMPERATURE STRAIN GAGE,

    DTIC Science & Technology

    The patent involves a high-temperature tensometer consisting of a strain-sensitive wire grid, a connecting and insulating material, a sub-layer of...heat-resistant material, deposited on the part being investigated or on a backing by gas flame deposition, and a connector to fasten the strain...adhesion, the tension-sensitive wire grid is fastened through the sub-layer to the part being tested by the connecting and insulating material. (Author)

  7. NUTRITION OF FIVE BACTEROIDES STRAINS

    PubMed Central

    Quinto, Grace

    1962-01-01

    Quinto, Grace (University of Kentucky College of Medicine, Lexington). Nutrition of five Bacteroides strains. J. Bacteriol. 84:559–562. 1962.—Some of the nutritional requirements of five gram-negative anaerobic bacilli, including Ristella perfoetens, Zuberella clostridiformis, and three Bacteroides strains freshly isolated from clinical exudates, were investigated. A fluid maintenance medium was developed in which the three freshly isolated strains, C-4, C-7, and C-2795, grew maximally in 12 to 24 hr. The maintenance medium contained 2.0% Trypticase and Proteose Peptone, 0.5% glucose, and 0.1% sodium thioglycolate; it was adjusted to pH 7.2 and supplemented with 0.1 μg of hemin/ml. Strains C-4, C-7, and C-2795 were cultivated through 14 serial cultures in fluid maintenance medium containing 0.1 μg of hemin/ml. The most satisfactory inoculum was a 1:100 or 1:1,000 dilution of a 24-hr seed culture. All the strains except Z. clostridiformis grew serially in a defined medium. R. perfoetens required pantothenic acid, nicotinic acid, and the following amino acids: histidine, tryptophan, tyrosine, valine, phenylalanine, cystine, and probably arginine, glutamic acid, methionine, glycine, isoleucine, leucine, and lysine. The C-4, C-7, and C-2795 strains required the hemin supplement in defined medium, but not vitamins, purines, or pyrimidines. PMID:13972793

  8. Applications of strained layer superlattices

    NASA Astrophysics Data System (ADS)

    Smith, D. L.; Laurich, B. K.; Mailhiot, C.

    1990-04-01

    Because of different band edge lineups, strain conditions, and growth orientations, various strained layer superlattice (SLS) materials can exhibit qualitatively new physical behavior in their optical properties. Two examples are given of new physical behavior in SLS: strain generated electric fields in polar growth axis superlattices and strained type 2 superlattices. In SLS, large electric fields can be generated by the piezoelectric effect. The fields are largest for SLS with a (111) growth axis; they vanish for SLS with a (100) growth axis. The strain generated electric fields strongly modify the optical properties of the superlattice. Photogenerated electron-hole pairs screen the fields leading to a large nonlinear optical response. Application of an external electric field leads to a large linear electrooptical response. The absorption edge can be either red or blue shifted. Optical studies of (100), (111), and (211) oriented GaInAs/GaAs superlattices confirm the existence of the strain generated electric fields. Small band gap semiconductors are useful for making intrinsic long wavelength infrared detectors. Arbitrarily small band gaps can be reached in the type 2 superlattice InAs/GaSb. However, for band gaps less than 0.1 eV, the layer thicknesses are large and the overlap of electron and hole wavefunctions are small. Thus, the absorption coefficient is too small for useful infrared (IR) detection. Including In in the GaSb introduces strain in he InAs/GaInSb superlattice which shifts the band edges so that small band gaps can be reached in thin layer superlattices. Good absorption at long IR wavelengths is thus achieved.

  9. Magnetic susceptibility, petrofabrics and strain

    NASA Astrophysics Data System (ADS)

    Borradaile, Graham John

    1988-12-01

    Magnetic susceptibility is a non-destructive technique for quantifying the average fabric of a small sample of rock. The interpretation of the magnetic fabric is not always straightforward. However, the principal directions of the magnitude ellipsoid of susceptibility commonly show orientations consistent with the kinematic interpretations of folds, shear zones and other structural features. The directions may correspond with the orientations of strained objects or with the planar-linear mineral orientations. There will usually be multiple mineralogical sources of susceptibility, often involving silicates. If the sources are known, or if the susceptibility can be attributed to a single mineral species, it may be possible to establish a correlation between the strain ellipsoid and the susceptibility ellipsoid. This correlation will be of principal directions in many instances and occasionally there may be a weak correlation of strain magnitudes as well. In other circumstances it may be possible to establish a correlation between changes in susceptibility and the strain. Nevertheless magnetic fabric studies are not routine substitutes for strain analysis. Even where information on strain is not provided, the magnetic fabrics (and subfabrics) yield a measure of the preferred crystallographic orientation or preferred dimensional orientation of the minerals that may be integrated profitably with other petrofabric data. Experimental deformation of certain synthetic aggregates indicates that directions of magnetic susceptibility spin rapidly with advancing strain, especially where the matrix grains undergo crystal-plastic deformation. In certain experiments, simple shear appears to change the intensity of magnetic fabric more effectively than pure shear. Experiments indicate also that the initial anisotropy of a rock-like material is not easily overprinted by deformation whereas field studies are equivocal.

  10. Optical Strain Measurement System Development

    NASA Technical Reports Server (NTRS)

    Lant, C. T.

    1985-01-01

    Investigations of physical phenomena affecting the durability of SSME components require measurement systems operational in hostile environments. The need for such instrumentation caused the definition and operation of an optical strain measurement system. This optical strain measurement system based on the speckle shift method is being developed. This is a noncontact, automatic method of measuring surface strain in one dimension that corrects for error due to rigid body motion. It provides a gauge length of 1 to 2 mm and allows the region of interest on the test specimen to be mapped point by point. The output is a graphics map of the points inspected on the specimen; data points is stored in quasi-real time. This is the first phase of a multiphase effort in optical strain measurement. The speckle pattern created by the test specimen is interpreted as high order interference fringes resulting from a random diffraction grating, being the natural surface roughness of the specimen. Strain induced on the specimen causes a change in spacing of the surface roughness, which in turn shifts the position of the interference pattern (speckles).

  11. Adaptation of a mixed culture of acidophiles for a tank biooxidation of refractory gold concentrates containing a high concentration of arsenic.

    PubMed

    Hong, Jeongsik; Silva, Rene A; Park, Jeonghyun; Lee, Eunseong; Park, Jayhyun; Kim, Hyunjung

    2016-05-01

    We adapted a mixed culture of acidophiles to high arsenic concentrations to confirm the possibility of achieving more than 70% biooxidation of refractory gold concentrates containing high arsenic (As) concentration. The biooxidation process was applied to refractory gold concentrates containing approximately 139.67 g/kg of total As in a stirred tank reactor using an adapted mixed culture of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. The percentage of the biooxidation process was analyzed based on the total As removal efficiency. The As removal was monitored by inductively coupled plasma (ICP) analysis, conducted every 24 h. The results obtained with the adapted culture were compared with the percentage of biooxidation obtained with a non-adapted mixed culture of A. ferrooxidans and A. thiooxidans, and with their respective pure cultures. The percentages of biooxidation obtained during 358 h of reaction were 72.20%, 38.20%, 27.70%, and 11.45% for adapted culture, non-adapted culture, and pure cultures of A. thiooxidans and A. ferrooxidans, respectively. The adapted culture showed a peak maximum percentage of biooxidation of 77% at 120 h of reaction, confirming that it is possible to obtain biooxidation percentages over 70% in gold concentrates containing high As concentrations.

  12. Analysis of Early Bacterial Communities on Volcanic Deposits on the Island of Miyake (Miyake-jima), Japan: a 6-year Study at a Fixed Site

    PubMed Central

    Fujimura, Reiko; Sato, Yoshinori; Nishizawa, Tomoyasu; Nanba, Kenji; Oshima, Kenshiro; Hattori, Masahira; Kamijo, Takashi; Ohta, Hiroyuki

    2012-01-01

    Microbial colonization on new terrestrial substrates represents the initiation of new soil ecosystem formation. In this study, we analyzed early bacterial communities growing on volcanic ash deposits derived from the 2000 Mount Oyama eruption on the island of Miyake (Miyake-jima), Japan. A site was established in an unvegetated area near the summit and investigated over a 6-year period from 2003 to 2009. Collected samples were acidic (pH 3.0–3.6), did not utilize any organic substrates in ECO microplate assays (Biolog), and harbored around 106 cells (g dry weight)−1 of autotrophic Fe(II) oxidizers by most-probable-number (MPN) counts. Acidithiobacillus ferrooxidans, Acidithiobacillus ferrivorans, and the Leptospirillum groups I, II and III were found to be abundant in the deposits by clone library analysis of bacterial 16S rRNA genes. The numerical dominance of Acidithiobacillus ferrooxidans was also supported by analysis of the gene coding for the large subunit of the form I ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO). Comparing the 16S rRNA gene clone libraries from samples differing in age, shifts in Fe(II)-oxidizing populations seemed to occur with deposit aging. The detection of known 16S rRNA gene sequences from Fe(III)-reducing acidophiles promoted us to propose the acidity-driven iron cycle for the early microbial ecosystem on the deposit. PMID:22075623

  13. Measuring mine roof bolt strains

    DOEpatents

    Steblay, Bernard J.

    1986-01-01

    A mine roof bolt and a method of measuring the strain in mine roof bolts of this type are disclosed. According to the method, a flat portion on the head of the mine roof bolt is first machined. Next, a hole is drilled radially through the bolt at a predetermined distance from the bolt head. After installation of the mine roof bolt and loading, the strain of the mine roof bolt is measured by generating an ultrasonic pulse at the flat portion. The time of travel of the ultrasonic pulse reflected from the hole is measured. This time of travel is a function of the distance from the flat portion to the hole and increases as the bolt is loaded. Consequently, the time measurement is correlated to the strain in the bolt. Compensation for various factors affecting the travel time are also provided.

  14. Photoacoustic spectroscopy of Entamoeba histolytica strains

    NASA Astrophysics Data System (ADS)

    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.

  15. Characterization of strains of Corynebacterium bovis.

    PubMed Central

    Brooks, B W; Barnum, D A

    1984-01-01

    The biochemical and morphological characteristics of 104 strains of Corynebacterium bovis isolated from bovine milk samples and the C. bovis reference strain were found to be uniform. Valuable criteria for identification were presence of catalase and oxidase, production of acid from glucose and fructose and a requirement for enriched basal media. Six strains of human and three strains of bovine origin were found to be inconsistent with the reference strain. PMID:6722650

  16. Chronic occupational repetitive strain injury.

    PubMed Central

    O'Neil, B. A.; Forsythe, M. E.; Stanish, W. D.

    2001-01-01

    OBJECTIVE: To review common repetitive strain injuries (RSIs) that occur in the workplace, emphasizing diagnosis, treatment, and etiology of these conditions. QUALITY OF EVIDENCE: A MEDLINE search from January 1966 to June 1999 focused on articles published since 1990 because RSIs are relatively new diagnoses. MeSH headings that were explored using the thesaurus included "cumulative trauma disorder," "overuse injury," and "repetitive strain injury." The search was limited to English articles only, and preference was given to randomized controlled trials. MAIN MESSAGE: Repetitive strain injuries result from repeated stress to the body's soft tissue structures including muscles, tendons, and nerves. They often occur in patients who perform repetitive movements either in their jobs or in extracurricular activities. Common RSIs include tendon-related disorders, such as rotator cuff tendonitis, and peripheral nerve entrapment disorders, such as carpal tunnel syndrome. A careful history and physical examination often lead to the diagnosis, but newer imaging techniques, such as magnetic resonance imaging and ultrasound, can help in refractory cases. Conservative management with medication, physiotherapy, or bracing is the mainstay of treatment. Surgery is reserved for cases that do not respond to treatment. CONCLUSION: Repetitive strain injury is common; primary care physicians must establish a diagnosis and, more importantly, its relationship to occupation. Treatment can be offered by family physicians who refer to specialists for cases refractory to conservative management. PMID:11228032

  17. Trials with a Strain Gauge.

    ERIC Educational Resources Information Center

    Auty, Geoff

    1996-01-01

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

  18. Bacteriocins and novel bacterial strains.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    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...

  19. Extreme Temperature Strain Measurement System

    DTIC Science & Technology

    1990-08-01

    Electrix Industries, Inc., P.O. Box 306, Lombard, IL 60148, Phone (312) 627-6802 38 Foil Strain gages. ° HiTEC Corp., Nardone Industrial Park...Planer Ltd., CERL-Planer Capacitive Transducer, Windmill Road, Sunbury -on- Thames, Middx., England, Phone: Sunbury 86262-3-4-5 • HiTEC Corp., Nardone

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

    PubMed

    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.

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

    SciTech Connect

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

    2016-01-19

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

  2. Strains

    MedlinePlus

    Pulled muscle ... can include: Pain and difficulty moving the injured muscle Discolored and bruised skin Swelling ... if you still have pain. Rest the pulled muscle for at least a day. If possible, keep ...

  3. Modelling to very high strains

    NASA Astrophysics Data System (ADS)

    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

  4. Strain tolerant microfilamentary superconducting wire

    DOEpatents

    Finnemore, Douglas K.; Miller, Theodore A.; Ostenson, Jerome E.; Schwartzkopf, Louis A.; Sanders, Steven C.

    1993-02-23

    A strain tolerant microfilamentary wire capable of carrying superconducting currents is provided comprising a plurality of discontinuous filaments formed from a high temperature superconducting material. The discontinuous filaments have a length at least several orders of magnitude greater than the filament diameter and are sufficiently strong while in an amorphous state to withstand compaction. A normal metal is interposed between and binds the discontinuous filaments to form a normal metal matrix capable of withstanding heat treatment for converting the filaments to a superconducting state. The geometry of the filaments within the normal metal matrix provides substantial filament-to-filament overlap, and the normal metal is sufficiently thin to allow supercurrent transfer between the overlapped discontinuous filaments but is also sufficiently thick to provide strain relief to the filaments.

  5. Virtual strain gage size study

    DOE PAGES

    Reu, Phillip L.

    2015-09-22

    DIC is a non-linear low-pass spatial filtering operation; whether we consider the effect of the subset and shape function, the strain window used in the strain calculation, of other post-processing of the results, each decision will impact the spatial resolution, of the measurement. More fundamentally, the speckle size limits, the spatial resolution by dictating the smallest possible subset. After this decision the processing settings are controlled by the allowable noise level balanced by possible bias errors created by the data filtering. This article describes a process to determine optimum DIC software settings to determine if the peak displacements or strainsmore » are being found.« less

  6. Strain softening in stretched DNA

    PubMed Central

    Luan, Binquan; Aksimentiev, Aleksei

    2010-01-01

    The microscopic mechanics of DNA stretching was characterized using extensive molecular dynamics simulations. By employing an anisotropic pressure control method, realistic force-extension dependences of effectively infinite DNA molecules were obtained. A coexistence of B- and S-DNA domains was observed during the overstretching transition. The simulations revealed that strain softening may occur in the process of stretching torsionally constrained DNA. The latter observation was qualitatively reconciled with available experimental data using a random-field Ising model. PMID:18851334

  7. High Temperature Capacitive Strain Gage

    NASA Technical Reports Server (NTRS)

    Wnuk, Stephen P., Jr.; Wnuk, Stephen P., III; Wnuk, V. P.

    1990-01-01

    Capacitive strain gages designed for measurements in wind tunnels to 2000 F were built and evaluated. Two design approaches were followed. One approach was based on fixed capacitor plates with a movable ground plane inserted between the plates to effect differential capacitive output with strain. The second approach was based on movable capacitor plates suspended between sapphire bearings, housed in a rugged body, and arranged to operate as a differential capacitor. A sapphire bearing gage (1/4 in. diameter x 1 in. in size) was built with a range of 50,000 and a resolution of 200 microstrain. Apparent strain on Rene' 41 was less than + or - 1000 microstrain from room temperature to 2000 F. Three gage models were built from the Ground Plane Differential concept. The first was 1/4 in. square by 1/32 in. high and useable to 700 F. The second was 1/2 in. square by 1/16 in. high and useable to 1440 F. The third, also 1/2 in. square by 1/16 in. high was expected to operate in the 1600 to 2000 F range, but was not tested because time and funding ended.

  8. High temperature capacitive strain gage

    NASA Astrophysics Data System (ADS)

    Wnuk, Stephen P., Jr.; Wnuk, Stephen P., III; Wnuk, V. P.

    1990-01-01

    Capacitive strain gages designed for measurements in wind tunnels to 2000 F were built and evaluated. Two design approaches were followed. One approach was based on fixed capacitor plates with a movable ground plane inserted between the plates to effect differential capacitive output with strain. The second approach was based on movable capacitor plates suspended between sapphire bearings, housed in a rugged body, and arranged to operate as a differential capacitor. A sapphire bearing gage (1/4 in. diameter x 1 in. in size) was built with a range of 50,000 and a resolution of 200 microstrain. Apparent strain on Rene' 41 was less than + or - 1000 microstrain from room temperature to 2000 F. Three gage models were built from the Ground Plane Differential concept. The first was 1/4 in. square by 1/32 in. high and useable to 700 F. The second was 1/2 in. square by 1/16 in. high and useable to 1440 F. The third, also 1/2 in. square by 1/16 in. high was expected to operate in the 1600 to 2000 F range, but was not tested because time and funding ended.

  9. Strain-Detecting Composite Materials

    NASA Technical Reports Server (NTRS)

    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.

  10. Strains and Sprains Are a Pain

    MedlinePlus

    ... strain at some point. Strains and sprains are common injuries, especially for kids who are very active or ... such as twisting your ankle. This kind of injury is common in sports, but also can happen any time ...

  11. Strain Monitoring of Flexible Structures

    NASA Technical Reports Server (NTRS)

    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.

  12. Turbulent Plane Wakes Subjected to Successive Strains

    NASA Technical Reports Server (NTRS)

    Rogers, Michael M.

    2003-01-01

    Six direct numerical simulations of turbulent time-evolving strained plane wakes have been examined to investigate the response of a wake to successive irrotational plane strains of opposite sign. The orientation of the applied strain field has been selected so that the flow is the time-developing analogue of a spatially developing wake evolving in the presence of either a favourable or an adverse streamwise pressure gradient. The magnitude of the applied strain rate a is constant in time t until the total strain e(sup at) reaches about four. At this point, a new simulation is begun with the sign of the applied strain being reversed (the original simulation is continued as well). When the total strain is reduced back to its original value of one, yet another simulation is begun with the sign of the strain being reversed again back to its original sign. This process is done for both initially "favourable" and initially "adverse" strains, providing simulations for each of these strain types from three different initial conditions. The evolution of the wake mean velocity deficit and width is found to be very similar for all the adversely strained cases, with both measures rapidly achieving exponential growth at the rate associated with the cross-stream expansive strain e(sup at). In the "favourably" strained cases, the wake widths approach a constant and the velocity deficits ultimately decay rapidly as e(sup -2at). Although all three of these cases do exhibit the same asymptotic exponential behaviour, the time required to achieve this is longer for the cases that have been previously adversely strained (by at approx. equals 1). These simulations confirm the generality of the conclusions drawn in Rogers (2002) regarding the response of plane wakes to strain. The evolution of strained wakes is not consistent with the predictions of classical self-similar analysis; a more general equilibrium similarity solution is required to describe the results. At least for the cases

  13. Using BEEM To Probe Strains In Semiconductors

    NASA Technical Reports Server (NTRS)

    Bell, L. Douglas; Milliken, Autumn M.; Manion, Stephen J.; Kaiser, William J.

    1996-01-01

    Ballistic-electron-emission microscopy (BEEM) useful in determining strains in semiconductors under some conditions. More specifically, BEEM is variant of scanning tunneling microscopy and sensitive to electronic structure of probed material. In present approach, BEEM used to obtain data on those aspects of variations in electronic structures related to variations in strains. Then by use of mathematical modeling of relationships between electronic structures and strains, variations in strains deduced from BEEM data.

  14. Temperature-Compensating Inactive Strain Gauge

    NASA Technical Reports Server (NTRS)

    Moore, Thomas C., Sr.

    1993-01-01

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

  15. Optical Fibers Would Sense Local Strains

    NASA Technical Reports Server (NTRS)

    Egalon, Claudio O.; Rogowski, Robert S.

    1994-01-01

    Proposed fiber-optic transducers measure local strains. Includes lead-in and lead-out lengths producing no changes in phase shifts, plus short sensing length in which phase shift is sensitive to strain. Phase shifts in single-mode fibers vary with strains. In alternative version, multiple portions of optical fiber sensitive to strains characteristic of specific vibrational mode of object. Same principle also used with two-mode fiber.

  16. Strain Rate Effects on Ultimate Strain of Copper

    DTIC Science & Technology

    1979-05-01

    34Dogbone" Specimen Used for Quasi-Static 5 and Intermediate Rate Tests 2 Schematic of Split Hopkinso’v Bar Apparatus 7 3a PETN Filled Tube Specimen...48 Experiment 25 Calculated Stress Components in Copper Cylinder 52 Expanded by PETN 26 Fracture of Explosively Expanded Cylindrical 54 Tube A-la...Record of Shot No. 10 73 A7b Framing Camera Record of Shot No. 10 74 A-8 Strain Versus Time for Copper Tube Expanded 75 by PETN vi

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

    PubMed Central

    Gangaiah, Dharanesh; Webb, Kristen M.; Humphreys, Tricia L.; Fortney, Kate R.; Toh, Evelyn; Tai, Albert; Katz, Samantha S.; Pillay, Allan; Chen, Cheng-Yen; Roberts, Sally A.; Munson, Robert S.; Spinola, Stanley M.

    2015-01-01

    Background 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? Methodology/Principal Findings 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. Conclusions/Significance 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. PMID:26147869

  18. Iron Meteorites Can Support the Growth of Acidophilic Chemolithoautotrophic Microorganisms

    NASA Astrophysics Data System (ADS)

    González-Toril, Elena; Martínez-Frías, Jesús; Gómez, José María; Rull, Fernando; Amils, Ricardo

    2005-06-01

    Chemolithoautotrophy based on reduced inorganic minerals is considered a primitive energy transduction system. Evidence that a high number of meteorites crashed into the planet during the early period of Earth history led us to test the ability of iron-oxidizing bacteria to grow using iron meteorites as their source of energy. Here we report the growth of two acidophilic iron-oxidizing bacteria, Leptospirillum ferrooxidans and Acidithiobacillus ferrooxidans, on a piece of the Toluca meteorite as the only source of energy. The alteration of the surface of the exposed piece of meteorite, the solubilization of its oxidized metal constituents, mainly ferric iron, and the formation of goethite precipitates all clearly indicate that iron-meteoritebased chemolithotrophic metabolism is viable.

  19. Iron meteorites can support the growth of acidophilic chemolithoautotrophic microorganisms.

    PubMed

    González-Toril, Elena; Martínez-Frías, Jesús; Gómez Gómez, José María; Rull, Fernando; Amils, Ricardo

    2005-06-01

    Chemolithoautotrophy based on reduced inorganic minerals is considered a primitive energy transduction system. Evidence that a high number of meteorites crashed into the planet during the early period of Earth history led us to test the ability of iron-oxidizing bacteria to grow using iron meteorites as their source of energy. Here we report the growth of two acidophilic iron-oxidizing bacteria, Leptospirillum ferrooxidans and Acidithiobacillus ferrooxidans, on a piece of the Toluca meteorite as the only source of energy. The alteration of the surface of the exposed piece of meteorite, the solubilization of its oxidized metal constituents, mainly ferric iron, and the formation of goethite precipitates all clearly indicate that iron-meteorite-based chemolithotrophic metabolism is viable.

  20. Monitoring Acidophilic Microbes with Real-Time Polymerase Chain Reaction (PCR) Assays

    SciTech Connect

    Frank F. Roberto

    2008-08-01

    Many techniques that are used to characterize and monitor microbial populations associated with sulfide mineral bioleaching require the cultivation of the organisms on solid or liquid media. Chemolithotrophic species, such as Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans, or thermophilic chemolithotrophs, such as Acidianus brierleyi and Sulfolobus solfataricus can grow quite slowly, requiring weeks to complete efforts to identify and quantify these microbes associated with bioleach samples. Real-time PCR (polymerase chain reaction) assays in which DNA targets are amplified in the presence of fluorescent oligonucleotide primers, allowing the monitoring and quantification of the amplification reactions as they progress, provide a means of rapidly detecting the presence of microbial species of interest, and their relative abundance in a sample. This presentation will describe the design and use of such assays to monitor acidophilic microbes in the environment and in bioleaching operations. These assays provide results within 2-3 hours, and can detect less than 100 individual microbial cells.

  1. Bioleaching kinetics and multivariate analysis of spent petroleum catalyst dissolution using two acidophiles.

    PubMed

    Pradhan, Debabrata; Mishra, Debaraj; Kim, Dong J; Ahn, Jong G; Chaudhury, G Roy; Lee, Seoung W

    2010-03-15

    Bioleaching studies were conducted to evaluate the recovery of metal values from waste petroleum catalyst using two different acidophilic microorganisms, Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans. Various leaching parameters such as contact time, pH, oxidant concentration, pulp densities, particle size, and temperature were studied in detail. Activation energy was evaluated from Arrhenius equation and values for Ni, V and Mo were calculated in case of both the acidophiles. In both cases, the dissolution kinetics of Mo was lower than those of V and Ni. The lower dissolution kinetics may have been due to the formation of a sulfur product layer, refractoriness of MoS(2) or both. Multivariate statistical data were presented to interpret the leaching data in the present case. The significance of the leaching parameters was derived through principle component analysis and multi linear regression analyses for both iron and sulfur oxidizing bacteria.

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

    PubMed

    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.

  3. Bioproduction of ferric sulfate used during heavy metals removal from sewage sludge.

    PubMed

    Drogui, Patrick; Mercier, Guy; Blais, Jean-François

    2005-01-01

    Toxic metals removal from wastewater sewage sludge can be achieved through microbial processes involving Acidithiobacillus ferrooxidans. The oxidation of ferrous ions by A. ferrooxidans, cultured in sewage sludge filtrate, was studied in both batch and continuous flow stirred tank reactors. Sewage sludge filtrate containing natural nutrients (phosphorus and nitrogen) was recovered as effluent following the dehydration of a primary and secondary sludge mixture. Batch and continuous flow stirred tank reactor tests demonstrated that A. ferrooxidans were able to grow and completely oxidize ferrous iron in a culture medium containing more than 80% (v v(-1)) sewage sludge filtrate with 10 g Fe(II) L(-1) added. Toxic levels were reached when total organic carbon in the sewage sludge filtrate exceeded 250 mg L(-1). The ferric iron solution produced in the sludge filtrate by A. ferrooxidans was used to solubilize heavy metals in primary and secondary sludge. The solubilization of Cu, Cr, and Zn yielded 71, 49, and 80%, respectively. This is comparable with the yield percentages obtained using a FeCl(3) solution. The cost of treating wastewater sewage sludge by bioproducing a ferric ion solution from sewage sludge is three times less expensive than the conventional method requiring a commercial ferric chloride solution.

  4. Electrochemistry of a semiconductor chalcopyrite concentrate leaching by Thiobacillus ferrooxidans

    SciTech Connect

    Torma, A.E.

    1991-01-01

    Using carbon-paste-CuFeS{sub 2} electrodes and a cyclic voltammetric technique, it was found that a large number of intermediate electrochemical oxidation reactions were associated with the dissolution of chalcopyrite in presence and absence of bacteria. The effects of concentrations of copper, ferrous and ferric ions, as well as of agitation on the peaks of cyclic voltammograms were measured. It was established that chalcopyrite oxidation was solid-state controlled as suggested by the data of chronopotentiometric and chronoamperometric measurements. The activation energy of solid state diffusion of chalcopyrite leaching was determined by the Sand's method to be {triangle}E{sub a} = 20.5 kJ. The leaching mechanism is discussed in terms of solid-state properties (energy bonding) of the n-type semiconductor chalcopyrite and energy density states of redox systems of acidic bacterial leach media. A generalized model for the mechanism of chalcopyrite leaching in presence and absence of bacteria is presented. 23 refs., 10 figs.

  5. Effect of strain and strain rate on residual microstructures in copper

    SciTech Connect

    Stevens, M.F.; Follansbee, P.S.

    1986-01-01

    Several specimens of OFE Cu were deformed in compression to study the resulting microstructures at equivalent levels of threshold stress and strain. Equiaxed, diffuse dislocation cells are more persistent in Cu when tested at strain rates exceeding 10/sup 3/ sec/sup -1/. At quasi-static strain rates, dislocation collapse into more distinct, narrow microbands occurs at lower strain levels.

  6. Error quantification in strain mapping methods.

    PubMed

    Guerrero, Elisa; Galindo, Pedro; Yáñez, Andrés; Ben, Teresa; Molina, Sergio I

    2007-10-01

    In this article a method for determining errors of the strain values when applying strain mapping techniques has been devised. This methodology starts with the generation of a thickness/defocus series of simulated high-resolution transmission electron microscopy images of InAsxP1-x/InP heterostructures and the application of geometric phase. To obtain optimal defocusing conditions, a comparison of different defocus values is carried out by the calculation of the strain profile standard deviations among different specimen thicknesses. Finally, based on the analogy of real state strain to a step response, a characterization of strain mapping error near an interface is proposed.

  7. Tests of strain analysis by experimental deformation

    NASA Astrophysics Data System (ADS)

    Borradaile, G. J.; McArthur, J.

    1991-01-01

    The linearisation method and Robin's method of strain analysis of granular materials yield accurate strain estimates for a variety of materials deformed experimentally in pure shear. The breakdown of continuum behaviour at high pore fluid pressures causes the methods to overestimate the strain because they do not take added rigid-body rotation into account. Both methods tolerate some variation in initial shape ratio and some degree of initial preferred orientation at modest strains. Results of tests on polymict sandstone indicate that the lower than average ductility of competent clasts may be balanced against an unfavourable degree of preferred orientation to yield an improved strain estimate.

  8. Radio-Frequency Strain Monitor

    NASA Technical Reports Server (NTRS)

    Heyman, Joseph S.; Rogowski, Robert S.; Holben, Milford S., Jr.

    1988-01-01

    Radio-frequency (RF) strain monitor developed to measure lengths of objects. RF waveguide or cable bonded to structure monitored. Propagation of RF signal along waveguide results in phase shift proportional to length of path traveled. Impedance mismatches placed in RF cable at nodes of structure. Records mismatches and detects overall length of line and lengths of intervals between nodes. Used to detect changes in elements of large structure with single cable. Monitor has potential for many applications, including monitoring stability of such large structures as aircraft, bridges, and buildings in Earthquake zones.

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

    NASA Technical Reports Server (NTRS)

    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. Strain engineering of graphene: a review

    NASA Astrophysics Data System (ADS)

    Si, Chen; Sun, Zhimei; Liu, Feng

    2016-02-01

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

  11. Multiplicative earthquake likelihood models incorporating strain rates

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    SUMMARYWe examine the potential for <span class="hlt">strain</span>-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 <span class="hlt">strain</span>-rates for the New Zealand region. Three components of the <span class="hlt">strain</span> rate estimated from GPS data over the period 1991-2011 are considered: the shear, rotational and dilatational <span class="hlt">strain</span> 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 <span class="hlt">strain</span> rate estimates. The shear <span class="hlt">strain</span> rate is overall the most informative individual covariate, as indicated by Molchan error diagrams as well as multiplicative modelling. Most models including <span class="hlt">strain</span> rates are significantly more informative than the best models excluding <span class="hlt">strain</span> rates in both the fitting and testing period. A hybrid that combines the shear and dilatational <span class="hlt">strain</span> rates with a smoothed seismicity covariate is the most informative model in the fitting period, and a simpler model without the dilatational <span class="hlt">strain</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25503536','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25503536"><span><span class="hlt">Strain</span> effects on oxygen migration in perovskites.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mayeshiba, Tam; Morgan, Dane</p> <p>2015-01-28</p> <p>Fast oxygen transport materials are necessary for a range of technologies, including efficient and cost-effective solid oxide fuel cells, gas separation membranes, oxygen sensors, chemical looping devices, and memristors. <span class="hlt">Strain</span> is often proposed as a method to enhance the performance of oxygen transport materials, but the magnitude of its effect and its underlying mechanisms are not well-understood, particularly in the widely-used perovskite-structured oxygen conductors. This work reports on an ab initio prediction of <span class="hlt">strain</span> effects on migration energetics for nine perovskite systems of the form LaBO3, where B = [Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Ga]. Biaxial <span class="hlt">strain</span>, as might be easily produced in epitaxial systems, is predicted to lead to approximately linear changes in migration energy. We find that tensile biaxial <span class="hlt">strain</span> reduces the oxygen vacancy migration barrier across the systems studied by an average of 66 meV per percent <span class="hlt">strain</span> for a single selected hop, with a low of 36 and a high of 89 meV decrease in migration barrier per percent <span class="hlt">strain</span> across all systems. The estimated range for the change in migration barrier within each system is ±25 meV per percent <span class="hlt">strain</span> when considering all hops. These results suggest that <span class="hlt">strain</span> can significantly impact transport in these materials, e.g., a 2% tensile <span class="hlt">strain</span> can increase the diffusion coefficient by about three orders of magnitude at 300 K (one order of magnitude at 500 °C or 773 K) for one of the most <span class="hlt">strain</span>-responsive materials calculated here (LaCrO3). We show that a simple elasticity model, which assumes only dilative or compressive <span class="hlt">strain</span> in a cubic environment and a fixed migration volume, can qualitatively but not quantitatively model the <span class="hlt">strain</span> dependence of the migration energy, suggesting that factors not captured by continuum elasticity play a significant role in the <span class="hlt">strain</span> response.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4222745','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4222745"><span>Distribution of Nontuberculous Mycobacteria <span class="hlt">strains</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2013-01-01</p> <p>Aim Mycobacteria other than tuberculosis (MOTT) cause increasingly serious infections especially in immunosuppressive patients by direct transmission from the environment or after colonization. However, identification of these species is difficult because of the cost and difficulties in defining to species level. Identification and distribution of these species can help clinician in the choice of treatment. Materials and methods A total of 90 MOTT <span class="hlt">strains</span> obtained from four different centers were included in the study. These <span class="hlt">strains</span> were identified by sequence analysis of 16S rRNA and Hsp65 genetic regions. Results Accordingly, within the 90 MOTT <span class="hlt">strains</span>, 17 different species were identified. In order of frequency, these species were M. gordonea (n = 21), M. abscessus (n = 13), M. lentiflavum (n = 9), M. fortuitum (n = 8), M. intracellulare (n = 6), M. kumamotonense (n = 6), M. neoaurum (n = 5), M. chimaera (n = 5), M. alvei (n = 5), M. peregrinum (n = 3), M. canariasense (n = 3), M. flavescens (n = 1), M. mucogenicum (n = 1), M. chelona (n = 1), M. elephantis (n = 1), M. terrae (n = 1) and M. xenopi (n = 1). Most frequently identified MOTT species according to the geographical origin were as follows: M. abscessus was the most common species either in Istanbul or Malatya regions (n = 6, n = 6, consequently). While M. kumamotonense was the most frequent species isolated from Ankara region (n = 6), M. gordonea was the most common for Samsun region (n = 14). Conclusion Our study revealed that frequency of MOTT varies depending on the number of clinical samples and that frequency of these species were affected by the newly identified species as a result of the use of novel molecular methods. In conclusion, when establishing diagnosis and treatment methods, it is important to know that infections caused by unidentified MOTT species may vary according to the regions in Turkey. The results</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26902321','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26902321"><span>Comparison of <span class="hlt">Strain</span> Rosettes and Digital Image Correlation for Measuring Vertebral Body <span class="hlt">Strain</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gustafson, Hannah; Siegmund, Gunter; Cripton, Peter</p> <p>2016-05-01</p> <p><span class="hlt">Strain</span> gages are commonly used to measure bone <span class="hlt">strain</span>, but only provide <span class="hlt">strain</span> at a single location. Digital image correlation (DIC) is an optical technique that provides the displacement, and therefore <span class="hlt">strain</span>, over an entire region of interest on the bone surface. This study compares vertebral body <span class="hlt">strains</span> measured using <span class="hlt">strain</span> gages and DIC. The anterior surfaces of 15 cadaveric porcine vertebrae were prepared with a <span class="hlt">strain</span> rosette and a speckled paint pattern for DIC. The vertebrae were loaded in compression with a materials testing machine, and two high-resolution cameras were used to image the anterior surface of the bones. The mean noise levels for the <span class="hlt">strain</span> rosette and DIC were 1 με and 24 με, respectively. Bland-Altman analysis was used to compare <span class="hlt">strain</span> from the DIC and rosette (excluding 44% of trials with some evidence of <span class="hlt">strain</span> rosette failure or debonding); the mean difference ± 2 standard deviations (SDs) was -108 με ± 702 με for the minimum (compressive) principal <span class="hlt">strain</span> and -53 με ± 332 με for the maximum (tensile) principal <span class="hlt">strain</span>. Although the DIC has higher noise, it avoids the relatively high risk we observed of <span class="hlt">strain</span> gage debonding. These results can be used to develop guidelines for selecting a method to measure <span class="hlt">strain</span> on bone.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPC.1723b0001D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPC.1723b0001D"><span>Modeling competition between yeast <span class="hlt">strains</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>de Gee, Maarten; van Mourik, Hilda; de Visser, Arjan; Molenaar, Jaap</p> <p>2016-04-01</p> <p>We investigate toxin interference competition between S. cerevisiae colonies grown on a solid medium. In vivo experiments show that the outcome of this competition depends strongly on nutrient availability and cell densities. Here we present a new model for S. cerevisiae colonies, calculating the local height and composition of the colonies. The model simulates yeast colonies that show a good fit to experimental data. Simulations of colonies that start out with a homogeneous mixture of toxin producing and toxin sensitive cells can display remarkable pattern formation, depending on the initial ratio of the <span class="hlt">strains</span>. Simulations in which the toxin producing and toxin sensitive species start at nearby positions clearly show that toxin production is advantageous.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24518385','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24518385"><span>The many shades of prion <span class="hlt">strain</span> adaptation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Baskakov, Ilia V</p> <p>2014-01-01</p> <p>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 <span class="hlt">strains</span> 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 <span class="hlt">strain</span> adaptation. The current article discusses the remarkable parallels between phenomena of prion <span class="hlt">strain</span> adaptation that accompanies cross-species transmission and the evolution of synthetic prions occurring within the same host. Two alternative mechanisms underlying prion <span class="hlt">strain</span> adaptation and synthetic <span class="hlt">strain</span> evolution are discussed. The current article highlights the complexity of the prion transmission barrier and <span class="hlt">strain</span> adaptation and proposes that the phenomenon of prion adaptation is more common than previously thought.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA571154','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA571154"><span>SNIT: SNP Identification for <span class="hlt">Strain</span> Typing</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2011-01-01</p> <p>Durkin S, Schneewind O, Nierman WC: Genome sequencing and analysis of Yersina pestis KIM D27, an avirulent <span class="hlt">strain</span> exempt from select agent regulation. PLoS...gener- ated from next-generation sequencing (NGS) data, we selected the recently published Yersinia pestis KIM D27 genome [12]. The Y. pestis D27 <span class="hlt">strain</span>...is a deriva- tive of Y. pestis KIM 10 <span class="hlt">strain</span> (accession no. NC_004088). The Y. pestis KIM D27 draft genome (accession no. ADDC00000000) was generated</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19840000339&hterms=vibrational+modes&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dvibrational%2Bmodes','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19840000339&hterms=vibrational+modes&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dvibrational%2Bmodes"><span>Deriving <span class="hlt">Strain</span> Modes From Vibrational Tests</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Young, J. W.; Joanides, J. C.</p> <p>1985-01-01</p> <p>Measurements and theoretical analysis complement each other. Experimental acceleration and <span class="hlt">strain</span> data used to calculate coefficients of low-frequency vibrational modes of object under test. An iterative comparison of experimental and calculated <span class="hlt">strains</span> give modal model of improved accuracy that predicts <span class="hlt">strains</span> under operating conditions. Method useful in fatigue life and reliability analyses of buildings, pumps, engines, vehicles, and other systems subject to vibrations and loud noises during operation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016MsT.........54S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016MsT.........54S"><span>Construction of an Optical Fiber <span class="hlt">Strain</span> Gauge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sulaiman, Najwa</p> <p></p> <p>This project is focused on the construction of an optical fiber <span class="hlt">strain</span> gauge that is based on a <span class="hlt">strain</span> gauge described by Butter and Hocker. Our gauge is designed to generate an interference pattern from the signals carried on two bare single-mode fibers that are fastened to an aluminum cantilever. When the cantilever experiences flexural stress, the interference pattern should change. By observing this change, it is possible to determine the <span class="hlt">strain</span> experienced by the cantilever. I describe the design and construction of our optical fiber <span class="hlt">strain</span> gauge as well as the characterization of different parts of the apparatus.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/912475','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/912475"><span>Measurement of Sorption-Induced <span class="hlt">Strain</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Eric P. Robertson; Richard L. Christiansen</p> <p>2005-05-01</p> <p><span class="hlt">Strain</span> 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 <span class="hlt">strain</span> on multiple small coal samples based on the optical detection of the longitudinal <span class="hlt">strain</span> instead of the more common usage of <span class="hlt">strain</span> 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 <span class="hlt">strain</span> data could be obtained in a shortened amount of time. A suite of <span class="hlt">strain</span> 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 <span class="hlt">strain</span> data obtained for pure gases. The sorption-induced <span class="hlt">strain</span> 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 <span class="hlt">strain</span> for the subbituminous coal over twice as great at the bituminous coal.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160000697','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160000697"><span>Acceleration and Velocity Sensing from Measured <span class="hlt">Strain</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pak, Chan-Gi; Truax, Roger</p> <p>2016-01-01</p> <p>A simple approach for computing acceleration and velocity of a structure from the <span class="hlt">strain</span> is proposed in this study. First, deflection and slope of the structure are computed from the <span class="hlt">strain</span> using a two-step theory. Frequencies of the structure are computed from the time histories of <span class="hlt">strain</span> using a parameter estimation technique together with an Autoregressive Moving Average model. From deflection, slope, and frequencies of the structure, acceleration and velocity of the structure can be obtained using the proposed approach. shape sensing, fiber optic <span class="hlt">strain</span> sensor, system equivalent reduction and expansion process.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20976649','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20976649"><span><span class="hlt">Strain</span> accommodation in inelastic deformation of glasses</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Murali, P.; Ramamurty, U.; Shenoy, Vijay B.</p> <p>2007-01-01</p> <p>Motivated by recent experiments on metallic glasses, we examine the micromechanisms of <span class="hlt">strain</span> accommodation including crystallization and void formation during inelastic deformation of glasses by employing molecular statics simulations. Our atomistic simulations with Lennard-Jones-like potentials suggests that a softer short range interaction between atoms favors crystallization. Compressive hydrostatic <span class="hlt">strain</span> in the presence of a shear <span class="hlt">strain</span> promotes crystallization whereas a tensile hydrostatic <span class="hlt">strain</span> is found to induce voids. The deformation subsequent to the onset of crystallization includes partial reamorphization and recrystallization, suggesting important atomistic mechanisms of plastic dissipation in glasses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/366503','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/366503"><span>Investigation of a noncontact <span class="hlt">strain</span> measurement technique</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Damiano, B.; Talarico, L.J.</p> <p>1996-05-01</p> <p>The goal of this project was to investigate the feasibility of a new noncontact technique for directly and continuously monitoring peak <span class="hlt">strain</span> in rotating components. The technique utilizes the unique <span class="hlt">strain</span>-sensitive magnetic material properties of transformation Induced Plasticity (TRIP) steel alloys to measure <span class="hlt">strain</span>. These alloys are weakly magnetic when unstrained but become strongly ferromagnetic after mechanical deformation. A computer study was performed to determine whether the <span class="hlt">strain</span>-induced change in the magnetic material properties of a TRIP steel gage bonded to a rotating component would cause significant perturbations in the magnetic flux of a stationary electromagnet. The effects of <span class="hlt">strain</span> level, distance between the rotating component and the stationary electromagnet, and motion-induced eddy currents on flux perturbation magnitude were investigated. The calculated results indicate that a TRIP steel <span class="hlt">strain</span> sensing element can cause a significant perturbation in the magnetic flux of a stationary electromagnet. The magnetic flux perturbation magnitude was found to be inversely proportional to the distance between the magnet face and the TRIP steel element and directly proportional to the TRIP steel <span class="hlt">strain</span> level. The effect of motion-induced eddy currents on the magnetic flux was found to be negligible. It appears that the technique can be successfully applied to measure peak <span class="hlt">strain</span> in rotating components; however, the sensitivity of the magnetic flux perturbation magnitude to the distance between the <span class="hlt">strain</span> sensing element and the electromagnet may require making an independent proximity measurement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/7453585','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/7453585"><span>[Antigenic relationships between Debaryomyces <span class="hlt">strains</span> (author's transl)].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Aksoycan, N</p> <p>1980-01-01</p> <p>The results of the agglutinations between homologous and heterologous Debaryomyces <span class="hlt">strains</span> and their agglutinating sera are shown in table I. According to these findings, D. hansenii and D. marama are antigenically different from other Debaryomyces <span class="hlt">strains</span> in this genus. In a previous study Aksoycan et al. have shown a common antigenic factor between D. hansenii, D. marama <span class="hlt">strains</span> and Salmonella 0:7 antigen. This factor was not present in other six <span class="hlt">strains</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012APS..MARV27001L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012APS..MARV27001L"><span>Making Novel Materials Using <span class="hlt">Strain</span> in Nanomembranes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lagally, Max G.</p> <p>2012-02-01</p> <p>The controlled introduction of <span class="hlt">strain</span> in materials offers an important degree of freedom for fundamental studies of materials as well as advanced device engineering. <span class="hlt">Strain</span> in a crystalline solid modifies the lattice constants and reduces the crystal symmetry. Because <span class="hlt">strain</span> energy is proportional to thickness, a free-standing crystalline thin sheet, which we call a nanomembrane (NM), can be <span class="hlt">strained</span> to a greater degree that a bulk material with the same surface area. I show the use of nanomembrane <span class="hlt">strain</span> engineering to make defect-free single crystals that cannot be grown any other way, and materials with <span class="hlt">strain</span> symmetries that they do not have naturally, in both cases alloys of Si and Ge. <span class="hlt">Strain</span> in NMs causes significant shifts in energy band edges, splitting of degenerate states, and changes in effective masses. These effects can be used to produce a desired band offset between different materials, to increase carrier mobility, and to change relative energy positions of valleys. In the latter respect, through the use of NMs it has recently become possible, using tensile <span class="hlt">strain</span>, to make Ge direct-bandgap and light emitting at room temperature. Periodic local stress can produce <span class="hlt">strain</span> superlattices and thus single-element heterojunctions. Work performed with the Roberto Paiella, Mark Eriksson, Feng Liu, and Irena Knezevic research groups.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/867015','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/867015"><span>Optical fiber sensor technique for <span class="hlt">strain</span> measurement</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Butler, Michael A.; Ginley, David S.</p> <p>1989-01-01</p> <p>Laser light from a common source is split and conveyed through two similar optical fibers and emitted at their respective ends to form an interference pattern, one of the optical fibers having a portion thereof subjected to a <span class="hlt">strain</span>. Changes in the <span class="hlt">strain</span> cause changes in the optical path length of the <span class="hlt">strain</span> fiber, and generate corresponding changes in the interference pattern. The interference pattern is received and transduced into signals representative of fringe shifts corresponding to changes in the <span class="hlt">strain</span> experienced by the <span class="hlt">strained</span> one of the optical fibers. These signals are then processed to evaluate <span class="hlt">strain</span> as a function of time, typical examples of the application of the apparatus including electrodeposition of a metallic film on a conductive surface provided on the outside of the optical fiber being <span class="hlt">strained</span>, so that <span class="hlt">strains</span> generated in the optical fiber during the course of the electrodeposition are measurable as a function of time. In one aspect of the invention, signals relating to the fringe shift are stored for subsequent processing and analysis, whereas in another aspect of the invention the signals are processed for real-time display of the <span class="hlt">strain</span> changes under study.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AcMSn..29..543X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AcMSn..29..543X"><span>Control of surface wettability via <span class="hlt">strain</span> engineering</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xiong, Wei; Liu, Jefferson Zhe; Zhang, Zhi-Liang; Zhen, Quan-Shui</p> <p>2013-08-01</p> <p>Reversible control of surface wettability has wide applications in lab-on-chip systems, tunable optical lenses, and microfluidic tools. Using a graphene sheet as a sample material and molecular dynamic simulations, we demonstrate that <span class="hlt">strain</span> engineering can serve as an effective way to control the surface wettability. The contact angles θ of water droplets on a graphene vary from 72.5° to 106° under biaxial <span class="hlt">strains</span> ranging from -10% to 10% that are applied on the graphene layer. For an intrinsic hydrophilic surface (at zero <span class="hlt">strain</span>), the variation of θ upon the applied <span class="hlt">strains</span> is more sensitive, i.e., from 0° to 74.8°. Overall the cosines of the contact angles exhibit a linear relation with respect to the <span class="hlt">strains</span>. In light of the inherent dependence of the contact angle on liquid-solid interfacial energy, we develop an analytic model to show the cos θ as a linear function of the adsorption energy E ads of a single water molecule over the substrate surface. This model agrees with our molecular dynamic results very well. Together with the linear dependence of E ads on biaxial <span class="hlt">strains</span>, we can thus understand the effect of <span class="hlt">strains</span> on the surface wettability. Thanks to the ease of reversibly applying mechanical <span class="hlt">strains</span> in micro/nano-electromechanical systems, we believe that <span class="hlt">strain</span> engineering can be a promising means to achieve the reversibly control of surface wettability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840004375','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840004375"><span>Inflatable device for installing <span class="hlt">strain</span> gage bridges</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cook, C. E.; Smith, G. E.; Monaghan, R. C. (Inventor)</p> <p>1983-01-01</p> <p>Methods and devices for installing in a tubular shaft multiple <span class="hlt">strain</span> gages are disclosed with focus on a method and a device for pneumatically forcing <span class="hlt">strain</span> gages into seated engagement with the internal surfaces of a tubular shaft in an installation of multiple <span class="hlt">strain</span> gages in a tubular shaft. The <span class="hlt">strain</span> gages or other electron devices are seated in a template-like component which is wrapped about a pneumatically expansible body. The component is inserted into a shaft and the body is pneumatically expanded after a suitable adhesive was applied to the surfaces.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002SPIE.4700..304A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002SPIE.4700..304A"><span>Microminiature temperature-compensated magnetoelastic <span class="hlt">strain</span> gauge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Arms, Steven W.; Townsend, Christopher P.</p> <p>2002-07-01</p> <p>Our objective was to demonstrate a microminiature magnetoelastic <span class="hlt">strain</span> gauge that provides both <span class="hlt">strain</span> and temperature signals without additional sensors. Iron based magnetoelastic materials were embedded within superelastic nickel/titanium (NiTi) tubing. NiTi stress was transferred to the ferrite, causing a permeability change sensed by a tiny coil. The coil/bridge was excited (70 KHz AC), synchronously demodulated, and amplified to produce a voltage output proportional to coil/ferrite impedance. A DC voltage was also applied and separately conditioned to provide an output proportional to coil resistance; this signal was used to provide thermal compensation. Controlled <span class="hlt">strains</span> were applied and 6 Hz cyclic outputs recorded simultaneously from the magnetoelastic <span class="hlt">strain</span> gauge and conventional foil <span class="hlt">strain</span> gauges. The magnetoelastic <span class="hlt">strain</span> gauge tracked the foil gauge with minimal hysteresis and good linearity over 600 microstrain; repeatability was approximately 1.5 microstrain. The magnetoelastic <span class="hlt">strain</span> gauge's gauge factor was computed from delta inductance/original inductance under static <span class="hlt">strain</span> conditions. Temperatures of 25-140 deg C resulted in an uncompensated shift of 15 microstrain/deg C, and compensated shift of 1.0 microstrain/deg C. A sensitive micro-magnetoelastic <span class="hlt">strain</span> gauge was demonstrated using the same sensor to detect stress and temperature with no moving parts, high gauge factor, and good thermal stability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014SPIE.9061E..31R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014SPIE.9061E..31R"><span>Distributed <span class="hlt">strain</span> monitoring for bridges: temperature effects</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Regier, Ryan; Hoult, Neil A.</p> <p>2014-03-01</p> <p>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 <span class="hlt">strain</span> sensors are one sensing technology that could provide comprehensive data for use in structural assessments as these systems potentially allow for <span class="hlt">strain</span> to be measured with the same accuracy and gage lengths as conventional <span class="hlt">strain</span> 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 <span class="hlt">strain</span> sensor system was installed on a section of a two span reinforced concrete bridge on the TransCanada Highway. <span class="hlt">Strain</span> 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 <span class="hlt">strain</span> measurements are affected by the bridge behavior as a whole. The <span class="hlt">strain</span> measurements due to temperature are compared to <span class="hlt">strain</span> 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 <span class="hlt">strain</span> changes similar to those due to a fully loaded transport truck. Future directions for research in this area are outlined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4644690','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4644690"><span>Skeletal muscle tensile <span class="hlt">strain</span> dependence: hyperviscoelastic nonlinearity</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Wheatley, Benjamin B; Morrow, Duane A; Odegard, Gregory M; Kaufman, Kenton R; Donahue, Tammy L Haut</p> <p>2015-01-01</p> <p>Introduction Computational modeling of skeletal muscle requires characterization at the tissue level. While most skeletal muscle studies focus on hyperelasticity, the goal of this study was to examine and model the nonlinear behavior of both time-independent and time-dependent properties of skeletal muscle as a function of <span class="hlt">strain</span>. Materials and Methods Nine tibialis anterior muscles from New Zealand White rabbits were subject to five consecutive stress relaxation cycles of roughly 3% <span class="hlt">strain</span>. Individual relaxation steps were fit with a three-term linear Prony series. Prony series coefficients and relaxation ratio were assessed for <span class="hlt">strain</span> dependence using a general linear statistical model. A fully nonlinear constitutive model was employed to capture the <span class="hlt">strain</span> dependence of both the viscoelastic and instantaneous components. Results Instantaneous modulus (p<0.0005) and mid-range relaxation (p<0.0005) increased significantly with <span class="hlt">strain</span> level, while relaxation at longer time periods decreased with <span class="hlt">strain</span> (p<0.0005). Time constants and overall relaxation ratio did not change with <span class="hlt">strain</span> level (p>0.1). Additionally, the fully nonlinear hyperviscoelastic constitutive model provided an excellent fit to experimental data, while other models which included linear components failed to capture muscle function as accurately. Conclusions Material properties of skeletal muscle are <span class="hlt">strain</span>-dependent at the tissue level. This <span class="hlt">strain</span> dependence can be included in computational models of skeletal muscle performance with a fully nonlinear hyperviscoelastic model. PMID:26409235</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2951977','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2951977"><span>Prion <span class="hlt">strain</span> interactions are highly selective</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Nilsson, K. Peter R.; Joshi-Barr, Shivanjali; Winson, Olivia; Sigurdson, Christina J.</p> <p>2010-01-01</p> <p>Various misfolded and aggregated neuronal proteins commonly co-exist in neurodegenerative disease, but whether the proteins co-aggregate and alter the disease pathogenesis is unclear. Here we used mixtures of distinct prion <span class="hlt">strains</span>, which are believed to differ in conformation, to test the hypothesis that two different aggregates interact and change the disease in vivo. We tracked two prion <span class="hlt">strains</span> in mice histopathologically and biochemically, as well as by spectral analysis of plaque-bound polythiophene acetic acid (PTAA), a conformation-sensitive fluorescent amyloid ligand. We found that prion <span class="hlt">strains</span> interacted in a highly selective and <span class="hlt">strain</span>-specific manner, with either (i) no interaction, (ii) hybrid plaque formation, or (iii) blockage of one <span class="hlt">strain</span> by a second (interference). The hybrid plaques were maintained upon further passage in vivo and each <span class="hlt">strain</span> seemed to maintain its original conformational properties, suggesting that one <span class="hlt">strain</span> served only as a scaffold for aggregation of the second <span class="hlt">strain</span>. These findings not only further our understanding of prion <span class="hlt">strain</span> interactions, but also directly demonstrate interactions that may occur in other protein aggregate mixtures. PMID:20826672</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/9749560','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/9749560"><span><span class="hlt">Strain</span> amplification in the bone mechanosensory system.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Cowin, S C; Weinbaum, S</p> <p>1998-09-01</p> <p>This article discusses the potential mechanisms by which the <span class="hlt">strain</span> induced at the membrane of an osteocyte may be amplified from the <span class="hlt">strain</span> experienced by the whole bone due to mechanical loading. These mechanisms address the question of how these mechanical load-induced small <span class="hlt">strains</span> of (typically) about 0.1% (but up to 0.5%) applied to a whole bone are amplified to <span class="hlt">strains</span> of 1% or larger at the membrane of the osteocyte buried in its lacuna in the bone matrix. The answer to this question is an important link in the mechanosensory system in bone and in relating in vitro cell studies to in vivo cellular response.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10878089','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10878089"><span>Surveillance of rotavirus <span class="hlt">strains</span> in the United States: identification of unusual <span class="hlt">strains</span>. The National Rotavirus <span class="hlt">Strain</span> Surveillance System collaborating laboratories.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Griffin, D D; Kirkwood, C D; Parashar, U D; Woods, P A; Bresee, J S; Glass, R I; Gentsch, J R</p> <p>2000-07-01</p> <p>Rotavirus <span class="hlt">strains</span> from 964 fecal specimens collected from children at 11 U.S. hospital laboratories from November 1997 to March 1998 and from samples collected at 12 laboratories from November 1998 to March 1999 were typed for G and P proteins. Serotype G1 was the predominant serotype in 1997-1998 (88%), followed by G2 (6.2%), G9 (3.3%), and G3 (1.5%). This pattern was similar to that seen in 1998-1999: G1 (79%), G2 (15%), G9 (3.0%), G4 (1.6%), and G3 (0.3%). Novel P[9] <span class="hlt">strains</span> were identified in both seasons, and analysis of a 364-nucleotide fragment from gene segment 4 of one of the <span class="hlt">strains</span> demonstrated 97.3% nucleotide identity with the prototype P3[9],G3 <span class="hlt">strain</span>, AU1, isolated in Japan. This is the first report of a human AU1-like <span class="hlt">strain</span> in the United States. These results reinforce our initial findings that serotype G9 persists in the United States but has not become a predominant <span class="hlt">strain</span> and that the common serotypes G1 to G4 account for almost 90% of <span class="hlt">strains</span> in circulation. Other uncommon <span class="hlt">strains</span> exist in the United States but may have been overlooked before because of their low prevalence and the use of inadequate diagnostic tools.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950047316&hterms=seismic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dseismic','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950047316&hterms=seismic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dseismic"><span>A comparison of eastern North American seismic <span class="hlt">strain</span>-rates to glacial rebound <span class="hlt">strain</span>-rates</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>James, Thomas S.; Bent, Allison L.</p> <p>1994-01-01</p> <p>Glacial rebound <span class="hlt">strain</span>-rates computed using a simple Laurentide glacial loading model are of the order of 10(exp -9) per year within the region of glaciation and extending several hundred kilometers beyond. The horizontal <span class="hlt">strain</span>-rates receive approximately equal contributions from horizontal and vertical velocities, a consequence of the spherical geometry adopted for the Earth model. In the eastern United States and southeastern Canada the computed <span class="hlt">strain</span>-rates are 1-3 orders of magnitude greater than an estimate of the average seismic <span class="hlt">strain</span>-rate (Anderson, 1986) and approximately 1 order of magnitude greater than predicted erosional <span class="hlt">strain</span>-rates. The predicted glacial rebound <span class="hlt">strain</span>-rates are not, in general, oriented in such a way as to augment the observed state of deviatoric stress, possibly explaining why the seismic <span class="hlt">strain</span>-rates are much smaller than the glacial rebound <span class="hlt">strain</span>-rates. An exception to this may be seismically active regions in the St. Lawrence valley.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=154276','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=154276"><span>Evolution of Sucrose Synthesis[w</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Lunn, John Edward</p> <p>2002-01-01</p> <p>Cyanobacteria and proteobacteria (purple bacteria) are the only prokaryotes known to synthesize sucrose (Suc). Suc-P synthase, Suc-phosphatase (SPP), and Suc synthase activities have previously been detected in several cyanobacteria, and genes coding for Suc-P synthase (sps) and Suc synthase (sus) have been cloned from Synechocystis sp. PCC 6803 and Anabaena (Nostoc) spp., respectively. An open reading frame in the Synechocystis genome encodes a predicted 27-kD polypeptide that shows homology to the maize (Zea mays) SPP. Heterologous expression of this putative spp gene in Escherichia coli, reported here, confirmed that this open reading frame encodes a functional SPP enzyme. The Synechocystis SPP is highly specific for Suc-6F-P (Km = 7.5 μm) and is Mg2+ dependent (Ka = 70 μm), with a specific activity of 46 μmol min−1 mg−1 protein. Like the maize SPP, the Synechocystis SPP belongs to the haloacid dehalogenase superfamily of phosphatases/hydrolases. Searches of sequenced microbial genomes revealed homologs of the Synechocystis sps gene in several other cyanobacteria (Nostoc punctiforme, Prochlorococcus marinus <span class="hlt">strains</span> MED4 and MIT9313, and Synechococcus sp. WH8012), and in three proteobacteria (<span class="hlt">Acidithiobacillus</span> <span class="hlt">ferrooxidans</span>, Magnetococcus sp. MC1, and Nitrosomonas europaea). Homologs of the Synechocystis spp gene were found in Magnetococcus sp. MC1 and N. punctiforme, and of the Anabaena sus gene in N. punctiforme and N. europaea. From analysis of these sequences, it is suggested that Suc synthesis originated in the proteobacteria or a common ancestor of the proteobacteria and cyanobacteria. PMID:11950997</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016IJN....1560005S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016IJN....1560005S"><span>Simulation and Analysis of <span class="hlt">Strain</span> Sensitivity of CNT-Based <span class="hlt">Strain</span> Sensors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sapra, Gaurav; Vig, Renu; Sharma, Manu</p> <p>2016-10-01</p> <p>Carbon nanotubes (CNT) is turning out to be a replacement to all the existing traditional sensors due to their high gauge factor, multidirectional sensing capability, high flexibility, low mass density, high dynamic range and high sensitivity to <span class="hlt">strains</span> at nano and macro- scales. The <span class="hlt">strain</span> sensitivity of CNT-based <span class="hlt">strain</span> sensors depends on number of parameters; quality and quantity of CNT used, type of polymer used, deposition and dispersion technique adopted and also on environmental conditions. Due to all these parameters, the piezoresistive behavior of CNT is diversified and it needs to be explored. This paper theoretically analyses the <span class="hlt">strain</span> sensitivity of CNT-based <span class="hlt">strain</span> sensors. The <span class="hlt">strain</span> sensitivity response of CNT <span class="hlt">strain</span> sensor is a result of change in total resistance of CNT network with respect to applied <span class="hlt">strain</span>. The total resistance of CNT network consists of intrinsic resistance and inter-tube resistance. It has been found that the change in intrinsic resistance under <span class="hlt">strain</span> is due to the variation of bandgap of individual, which depends on the chirality of the tube and it varies exponentially with <span class="hlt">strain</span>. The inter-tube resistance of CNT network changes nonlinearly due to change in distance between neighboring CNTs with respect to applied <span class="hlt">strain</span>. As the distance d between CNTs increases due to applied <span class="hlt">strain</span>, tunneling resistance Rtunnel increases nonlinearly in exponential manner. When the concentration of CNTs in composite is close to percolation threshold, then the change of inter-tube resistances is more dominant than intrinsic resistance. At percolation threshold, the total resistance of CNT networks changes nonlinearly and this effect of nonlinearity is due to tunneling effect. The <span class="hlt">strain</span> sensitivity of CNT-based <span class="hlt">strain</span> sensors also varies nonlinearly with the change in temperature. For the change of temperature from -20∘C to 50∘C, there is more than 100% change in <span class="hlt">strain</span> sensitivity of CNT/polymer composite <span class="hlt">strain</span> sensor. This change is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/495681','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/495681"><span>Bicrystals with <span class="hlt">strain</span> gradient effects</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Shu, J.Y.</p> <p>1997-01-09</p> <p>Boundary between two perfectly bonded single crystals plays an important role in determining the deformation of the bicrystals. This work addresses the role of the grain boundary by considering the elevated hardening of a slip system due to a slip gradient. The slip gradients are associated with geometrically necessary dislocations and their effects become pronounced when a representative length scale of the deformation field is comparable to the dominant microstructural length scale of a material. A new rate-dependent crystal plasticity theory is presented and has been implemented within the finite element method framework. A planar bicrystal under uniform in-plane loading is studied using the new crystal theory. The <span class="hlt">strain</span> is found to be continuous but nonuniform within a boundary layer around the interface. The lattice rotation is also nonuniform within the boundary layer. The width of the layer is determined by the misorientation of the grains, the hardening of slip systems, and most importantly by the characteristic material length scales. The overall yield strength of the bicrystal is also obtained. A significant grain-size dependence of the yield strength, the Hall- Petch effect is predicted.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=punishment+AND+child&pg=7&id=EJ808655','ERIC'); return false;" href="http://eric.ed.gov/?q=punishment+AND+child&pg=7&id=EJ808655"><span>General <span class="hlt">Strain</span> Theory and Delinquency: Focusing on the Influences of Key <span class="hlt">Strain</span> Characteristics on Delinquency</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Moon, Byongook; Blurton, David; McCluskey, John D.</p> <p>2008-01-01</p> <p>The study examines the effects of recent, older, and chronic <span class="hlt">strains</span> and of perceived injustice of <span class="hlt">strain</span> on delinquency, sampling 777 Korean youth. Seven key <span class="hlt">strains</span> 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,…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AIPC.1426..167J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AIPC.1426..167J"><span>High <span class="hlt">strain</span> rate behavior of polyurea compositions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Joshi, Vasant S.; Milby, Christopher</p> <p>2012-03-01</p> <p>High-<span class="hlt">strain</span>-rate response of three polyurea compositions with varying molecular weights has been investigated using a Split Hopkinson Pressure Bar arrangement equipped with aluminum bars. Three polyurea compositions were synthesized from polyamines (Versalink, Air Products) with a multi-functional isocyanate (Isonate 143L, Dow Chemical). Amines with molecular weights of 1000, 650, and a blend of 250/1000 have been used in the current investigation. These materials have been tested to <span class="hlt">strain</span> rates of over 6000/s. High <span class="hlt">strain</span> rate results from these tests have shown varying trends as a function of increasing <span class="hlt">strain</span>. While higher molecular weight composition show lower yield, they do not show dominant hardening behavior at lower <span class="hlt">strain</span>. On the other hand, the blend of 250/1000 show higher load bearing capability but lower <span class="hlt">strain</span> hardening effects than the 600 and 1000 molecular weight amine based materials. Results indicate that the initial increase in the modulus of the blend of 250/1000 may lead to the loss of <span class="hlt">strain</span> hardening characteristics as the material is compressed to 50% <span class="hlt">strain</span>, compared to 1000 molecular weight amine based material.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090011203','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090011203"><span>Nanocomposite <span class="hlt">Strain</span> Gauges Having Small TCRs</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gregory, Otto; Chen, Ximing</p> <p>2009-01-01</p> <p>Ceramic <span class="hlt">strain</span> gauges in which the <span class="hlt">strain</span>-sensitive electrically conductive strips made from nanocomposites of noble metal and indium tin oxide (ITO) are being developed for use in gas turbine engines and other power-generation systems in which gas temperatures can exceed 1,500 F (about 816 C). In general, <span class="hlt">strain</span> gauges exhibit spurious thermally induced components of response denoted apparent <span class="hlt">strain</span>. When temperature varies, a <span class="hlt">strain</span>-gauge material that has a nonzero temperature coefficient of resistance (TCR) exhibits an undesired change in electrical resistance that can be mistaken for the change in resistance caused by a change in <span class="hlt">strain</span>. It would be desirable to formulate straingauge materials having TCRs as small as possible so as to minimize apparent <span class="hlt">strain</span>. Most metals exhibit positive TCRs, while most semiconductors, including ITO, exhibit negative TCRs. The present development is based on the idea of using the negative TCR of ITO to counter the positive TCRs of noble metals and of obtaining the benefit of the ability of both ITO and noble metals to endure high temperatures. The noble metal used in this development thus far has been platinum. Combinatorial libraries of many ceramic <span class="hlt">strain</span> gauges containing nanocomposites of various proportions of ITO and platinum were fabricated by reactive co-sputtering from ITO and platinum targets onto alumina- and zirconia-based substrates mounted at various positions between the targets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19810000068&hterms=phase+locked+loop&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dphase%2Blocked%2Bloop','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19810000068&hterms=phase+locked+loop&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dphase%2Blocked%2Bloop"><span>Pulsed Phase-Locked-Loop <span class="hlt">Strain</span> Monitor</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Heyman, J. S.; Stone, F. D.</p> <p>1982-01-01</p> <p>P2sup.L2sup. <span class="hlt">strain</span> monitor measures <span class="hlt">strain</span> by monitoring change in phase of acoustic signal that passes through stressed sample. Phase sample causes shift in frequency of VCO. As with other monitors of this type, instrument is only accurate in elastic range of material. Monitor is expected to have broad application in materials testing, structural design, fabrication and assembly.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1993STIN...9426568W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1993STIN...9426568W"><span>Attachment techniques for high temperature <span class="hlt">strain</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wnuk, Steve P., Jr.</p> <p>1993-01-01</p> <p>Attachment methods for making resistive <span class="hlt">strain</span> measurements to 2500 F were studied. A survey of available <span class="hlt">strain</span> gages and attachment techniques was made, and the results are compiled for metal and carbon composite test materials. A theoretical analysis of <span class="hlt">strain</span> transfer into a bonded <span class="hlt">strain</span> gage was made, and the important physical parameters of the <span class="hlt">strain</span> transfer medium, the ceramic matrix, were identified. A pull tester to measure pull-out tests on commonly used <span class="hlt">strain</span> gage cements indicated that all cements tested displayed adequate strength for good <span class="hlt">strain</span> transfer. Rokide flame sprayed coatings produced significantly stronger bonds than ceramic cements. An in-depth study of the flame spray process produced simplified installation procedures which also resulted in greater reliability and durability. Application procedures incorporating improvements made during this program are appended to the report. <span class="hlt">Strain</span> gages installed on carbon composites, Rene' 41, 316 stainless steel, and TZM using attachment techniques developed during this program were successfully tested to 2500 F. Photographs of installation techniques, test procedures, and graphs of the test data are included in this report.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/8719177','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/8719177"><span>A natural vaccine candidate <span class="hlt">strain</span> against cholera.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, Y Q; Qi, G M; Wang, S X; Yu, Y M; Duan, G C; Zhang, L J; Gao, S Y</p> <p>1995-12-01</p> <p>E1 Tor Vibrio cholerae (EVC) <span class="hlt">strains</span> may be classified into two kinds-epidemigenic (EEVC) <span class="hlt">strains</span> and non-epidemigenic (NEEVC) <span class="hlt">strains</span>-based on a phage-biotyping system. A large number of EEVC <span class="hlt">strains</span> have been screened for toxigenic and putative colonization attributes. One such naturally occurring <span class="hlt">strains</span> (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 toxin-coregulated pilus A gene (icpA) although icpA is poorly expressed. It expresses type B pili but does not possess type C pili. It is an E1 Tor Ogawa <span class="hlt">strain</span> and does not cause fluid accumulation in rabbit ilcal loop tests. Active immunization of rabbits with <span class="hlt">strain</span> IEM101 elicited good protection against challenge with virulent <span class="hlt">strains</span> of V. cholerae O1. Oral administration caused no side effects in 15 human volunteers, colonized the gut for four to ten days and elicited good immune responses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=nursing+AND+care&id=EJ1001107','ERIC'); return false;" href="http://eric.ed.gov/?q=nursing+AND+care&id=EJ1001107"><span>Medically Complex Home Care and Caregiver <span class="hlt">Strain</span></span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Moorman, Sara M.; Macdonald, Cameron</p> <p>2013-01-01</p> <p>Purpose of the study: To examine (a) whether the content of caregiving tasks (i.e., nursing vs. personal care) contributes to variation in caregivers' <span class="hlt">strain</span> and (b) whether the level of complexity of nursing tasks contributes to variation in <span class="hlt">strain</span> among caregivers providing help with such tasks. Design and methods: The data came from the Cash…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19700000207','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19700000207"><span>Inorganic bonding of semiconductor <span class="hlt">strain</span> gages</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Woodruff, N. L.</p> <p>1970-01-01</p> <p>Inorganic bonding materials minimize outgassing and improve electrical and mechanical properties of semiconductor <span class="hlt">strain</span>-gage transducers in high-vacuum and high-temperature operations. The two basic methods described are ceramic-glass-bonding and metallic bond formation between the <span class="hlt">strain</span> gage and the substrate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/82645','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/82645"><span>On certain aspects of <span class="hlt">strain</span> rate sensitivity of sheet metals</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Shi, M.F.; Meuleman, D.J.</p> <p>1995-06-01</p> <p>The formability of a material depends upon the <span class="hlt">strain</span> hardening and <span class="hlt">strain</span> rate hardening of the material. In this study, constitutive parameters using the power law constitutive equation are determined for six different strength steels and two aluminum alloys over different <span class="hlt">strain</span> ranges, including approximations of the postuniform elongation range. Constitutive parameters are found to be different at different <span class="hlt">strain</span> ranges. The <span class="hlt">strain</span> hardening of steels increases with <span class="hlt">strain</span> at low <span class="hlt">strain</span> levels (less than 5%) and decreases at high <span class="hlt">strain</span> levels (greater than 10%). <span class="hlt">Strain</span> rate hardening decreases with <span class="hlt">strain</span> for all steels and aluminum alloys. Uniform elongation depends only on <span class="hlt">strain</span> hardening, and postuniform elongation depends only on <span class="hlt">strain</span> rate hardening. However, the total elongation depends on both <span class="hlt">strain</span> hardening and <span class="hlt">strain</span> rate hardening.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040090018&hterms=Mechanosensitive+channels&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DMechanosensitive%2Bchannels','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040090018&hterms=Mechanosensitive+channels&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DMechanosensitive%2Bchannels"><span>Transduction of mechanical <span class="hlt">strain</span> in bone</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Duncan, R. L.</p> <p>1995-01-01</p> <p>One physiologic consequence of extended periods of weightlessness is the rapid loss of bone mass associated with skeletal unloading. Conversely, mechanical loading has been shown to increase bone formation and stimulate osteoblastic function. The mechanisms underlying mechanotransduction, or how the osteoblast senses and converts biophysical stimuli into cellular responses has yet to be determined. For non-innervated mechanosensitive cells like the osteoblast, mechanotransduction can be divided into four distinct phases: 1) mechanocoupling, or the characteristics of the mechanical force applied to the osteoblast, 2) biochemical coupling, or the mechanism through which mechanical <span class="hlt">strain</span> is transduced into a cellular biochemical signal, 3) transmission of signal from sensor to effector cell and 4) the effector cell response. This review examines the characteristics of the mechanical <span class="hlt">strain</span> encountered by osteoblasts, possible biochemical coupling mechanisms, and how the osteoblast responds to mechanical <span class="hlt">strain</span>. Differences in osteoblastic responses to mechanical <span class="hlt">strain</span> are discussed in relation to the types of <span class="hlt">strain</span> encountered and the possible transduction pathways involved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26649476','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26649476"><span>Mechanical <span class="hlt">strain</span> effects on black phosphorus nanoresonators.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Cui-Xia; Zhang, Chao; Jiang, Jin-Wu; Park, Harold S; Rabczuk, Timon</p> <p>2016-01-14</p> <p>We perform classical molecular dynamics simulations to investigate the effects of mechanical <span class="hlt">strain</span> on single-layer black phosphorus nanoresonators at different temperatures. We find that the resonant frequency is highly anisotropic in black phosphorus due to its intrinsic puckered configuration, and that the quality factor in the armchair direction is higher than in the zigzag direction at room temperature. The quality factors are also found to be intrinsically larger than those in graphene and MoS2 nanoresonators. The quality factors can be increased by more than a factor of two by applying tensile <span class="hlt">strain</span>, with uniaxial <span class="hlt">strain</span> in the armchair direction being the most effective. However, there is an upper bound for the quality factor increase due to nonlinear effects at large <span class="hlt">strains</span>, after which the quality factor decreases. The tension induced nonlinear effect is stronger along the zigzag direction, resulting in a smaller maximum <span class="hlt">strain</span> for quality factor enhancement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24799688','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24799688"><span>Extraordinary <span class="hlt">strain</span> hardening by gradient structure.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wu, XiaoLei; Jiang, Ping; Chen, Liu; Yuan, Fuping; Zhu, Yuntian T</p> <p>2014-05-20</p> <p>Gradient structures have evolved over millions of years through natural selection and optimization in many biological systems such as bones and plant stems, where the structures change gradually from the surface to interior. The advantage of gradient structures is their maximization of physical and mechanical performance while minimizing material cost. Here we report that the gradient structure in engineering materials such as metals renders a unique extra <span class="hlt">strain</span> hardening, which leads to high ductility. The grain-size gradient under uniaxial tension induces a macroscopic <span class="hlt">strain</span> gradient and converts the applied uniaxial stress to multiaxial stresses due to the evolution of incompatible deformation along the gradient depth. Thereby the accumulation and interaction of dislocations are promoted, resulting in an extra <span class="hlt">strain</span> hardening and an obvious <span class="hlt">strain</span> hardening rate up-turn. Such extraordinary <span class="hlt">strain</span> hardening, which is inherent to gradient structures and does not exist in homogeneous materials, provides a hitherto unknown strategy to develop strong and ductile materials by architecting heterogeneous nanostructures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6565562','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6565562"><span><span class="hlt">Strain</span> rate effects in stress corrosion cracking</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Parkins, R.N. . Dept. of Metallurgy and Engineering Materials)</p> <p>1990-03-01</p> <p>Slow <span class="hlt">strain</span> 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 <span class="hlt">strain</span> 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 <span class="hlt">strain</span> 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 <span class="hlt">strain</span> tests, its extension to service situations may be less apparent. Laboratory work involving realistic stressing conditions, including low-frequency cyclic loading, shows that <span class="hlt">strain</span> or creep rates give good correlation with thresholds for cracking and with crack growth kinetics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..1810513Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..1810513Q"><span>Micro-scale <span class="hlt">strain</span> mapping technique: a tool to quantify <span class="hlt">strain</span> partitioning during creep deformation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Quintanilla-Terminel, Alejandra; Zimmerman, Mark; Evans, Brian; Kohlstedt, David</p> <p>2016-04-01</p> <p>Several deformation mechanisms interact to accommodate plastic deformation. Quantifying the contribution of each to the total <span class="hlt">strain</span> is necessary for establishing a better link between observed microstructures and mechanical data, as well as to allow more confident extrapolation from laboratory to natural conditions. In this contribution, we present the experimental and computational technique involved in micro-scale <span class="hlt">strain</span> mapping (MSSM). The MSSM technique relies on analyzing the relative displacement of initially regularly spaced markers after deformation. We present several microfabrication techniques that permit us to pattern various rocks with micrometric and nanometric metal markers, as well as the challenges faced in working at high temperatures and pressures. A Hough transform algorithm was used to detect the markers and automate as much as possible the <span class="hlt">strain</span> analysis. The von Mises <span class="hlt">strain</span> is calculated for a set of n-points and their relative displacements, which allow us to map the <span class="hlt">strain</span> at different length scales. We applied the MSSM technique to study <span class="hlt">strain</span> partitioning during deformation creep of Carrara marble and San Carlos olivine at a confining pressure, Pc, of 300 MPa and homologous temperatures of 0.3 to 0.6. We measured the local <span class="hlt">strain</span> and <span class="hlt">strain</span> heterogeneity produced during creep deformation of split cylinders of Carrara marble under conventional triaxial loading to inelastic <span class="hlt">strains</span> of 11 to 36% at a <span class="hlt">strain</span> rate of 3x10-5s-1, Pc = 300 MPa and 400o < T <700oC. We conclude that the evolution of deformation structures in marble takes place over a substantial interval in <span class="hlt">strain</span> and that the duration of this interval depends on <span class="hlt">strain</span> rate, temperature, and pressure. Our first results on <span class="hlt">strain</span> mapping of olivine deformed at T = 1150oC and Pc = 300 MPa demonstrate promise for characterizing intragranular <span class="hlt">strain</span> and better defining the contribution of grain boundary sliding to the total <span class="hlt">strain</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2551748','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2551748"><span>Amerindian Helicobacter pylori <span class="hlt">Strains</span> Go Extinct, as European <span class="hlt">Strains</span> Expand Their Host Range</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Domínguez-Bello, Maria G.; Pérez, Maria E.; Bortolini, Maria C.; Salzano, Francisco M.; Pericchi, Luis R.; Zambrano-Guzmán, Orlisbeth; Linz, Bodo</p> <p>2008-01-01</p> <p>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 <span class="hlt">strains</span> would be the least diverse. We analyzed the multilocus sequence (7 housekeeping genes) of 131 <span class="hlt">strains</span>: 19 cultured from Africans, 36 from Spanish, 11 from Koreans, 43 from Amerindians and 22 from South American Mestizos. We found that all <span class="hlt">strains</span> that had been cultured from Africans were African <span class="hlt">strains</span> (hpAfrica1), all from Spanish were European (hpEurope) and all from Koreans were hspEAsia but that Amerindians and Mestizos carried mixed <span class="hlt">strains</span>: hspAmerind and hpEurope <span class="hlt">strains</span> had been cultured from Amerindians and hpEurope and hpAfrica1 were cultured from Mestizos. The least genetically diverse H. pylori <span class="hlt">strains</span> were hspAmerind. <span class="hlt">Strains</span> hpEurope were the most diverse and showed remarkable multilocus sequence mosaicism (indicating recombination). The lower genetic structure in hpEurope <span class="hlt">strains</span> 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 <span class="hlt">strains</span> might be linked to their apparent tendency to disappear. This suggests that Amerindian <span class="hlt">strains</span> may lack the needed diversity to survive the diversity brought by non-Amerindian hosts. PMID:18830403</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28049090','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28049090"><span>New regime in the mechanical behavior of skin: <span class="hlt">strain</span>-softening occurring before <span class="hlt">strain</span>-hardening.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Nicolle, S; Decorps, J; Fromy, B; Palierne, J-F</p> <p>2017-05-01</p> <p>We report linear and non-linear shear tests on rat skin, evidencing a <span class="hlt">strain</span>-softening regime, from 1% to 50% <span class="hlt">strain</span>, followed by a strong <span class="hlt">strain</span>-hardening regime, leading to a 'deck chair-shaped' stress-<span class="hlt">strain</span> curve. The <span class="hlt">strain</span>-softening regime was never reported as such in the literature, possibly mistaken for the linear regime in experiments starting above 1% deformation. The time-dependent response is akin to that of a gel, with a power-law frequency-dependent dynamic shear modulus ranging from ~5.6kPa to ~10kPa between 0.1Hz and 10Hz. We present an analytical non-linear viscoelastic model that accounts for both time-dependent and <span class="hlt">strain</span>-dependent features of the skin. This eight-parameter model extends the one we proposed for parenchymatous organs by including <span class="hlt">strain</span>-softening.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23030102','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23030102"><span>Anisotropic <span class="hlt">strain</span> enhanced hydrogen solubility in bcc metals: the independence on the sign of <span class="hlt">strain</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhou, Hong-Bo; Jin, Shuo; Zhang, Ying; Lu, Guang-Hong; Liu, Feng</p> <p>2012-09-28</p> <p>When an impurity is doped in a solid, it inevitably induces a local stress, tending to expand or contract the lattice. Consequently, <span class="hlt">strain</span> can be applied to change the solubility of impurity in a solid. Generally, the solubility responds to <span class="hlt">strain</span> "monotonically," increasing (decreasing) with the tensile (compressive) <span class="hlt">strain</span> 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 <span class="hlt">strain</span> in some bcc metals, almost independent of the sign of <span class="hlt">strain</span>. This anomalous behavior is found to be caused by a continuous change of H location induced by anisotropic <span class="hlt">strain</span>. Our finding suggests a cascading effect of H bubble formation in bcc metals: the H solution leads to H bubble formation that induces anisotropic <span class="hlt">strain</span> that in turn enhances H solubility to further facilitate bubble growth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008IJMPB..22.1255K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008IJMPB..22.1255K"><span>Dynamic Tensile Properties of Iron and Steels for a Wide Range of <span class="hlt">Strain</span> Rates and <span class="hlt">Strain</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kojima, Nobusato; Hayashi, Hiroyuki; Yamamoto, Terumi; Mimura, Koji; Tanimura, Shinji</p> <p></p> <p>The tensile stress-<span class="hlt">strain</span> curves of iron and a variety of steels, covering a wide range of strength level, over a wide <span class="hlt">strain</span> rate range on the order of 10-3 ~ 103 s-1, were obtained systematically by using the Sensing Block Type High Speed Material Testing System (SBTS, Saginomiya). Through intensive analysis of these results, the <span class="hlt">strain</span> rate sensitivity of the flow stress for the large <span class="hlt">strain</span> region, including the viscous term at high <span class="hlt">strain</span> rates, the true fracture strength and the true fracture <span class="hlt">strain</span> were cleared for the material group of the ferrous metals. These systematical data may be useful to develop a practical constitutive model for computer codes, including a fracture criterion for simulations of the dynamic behavior in crash worthiness studies and of work-pieces subjected to dynamic plastic working for a wide <span class="hlt">strain</span> rate range.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007IJMSp.259..140K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007IJMSp.259..140K"><span>Specific identification of Bacillus anthracis <span class="hlt">strains</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Krishnamurthy, Thaiya; Deshpande, Samir; Hewel, Johannes; Liu, Hongbin; Wick, Charles H.; Yates, John R., III</p> <p>2007-01-01</p> <p>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 <span class="hlt">strains</span> of Bacillus anthracis, a human pathogen. Software termed Profiler was created to initially screen the MudPIT data of B. anthracis <span class="hlt">strains</span> and establish the observed proteins specific for its <span class="hlt">strains</span>. A database was also generated using Profiler containing marker proteins of B. anthracis and its <span class="hlt">strains</span>, which in turn could be used for detecting the organism and its corresponding <span class="hlt">strains</span> in samples. Analysis of the unknowns by our methodology, combining MudPIT and Profiler, led to the accurate identification of the anthracis <span class="hlt">strains</span> present in samples. Thus, a new approach for the identification of B. anthracis <span class="hlt">strains</span> in unknown samples, based on the molecular mass and sequences of marker proteins, has been ascertained.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006PMB....51.5245T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006PMB....51.5245T"><span>Resolution of axial shear <span class="hlt">strain</span> elastography</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thitaikumar, Arun; Righetti, Raffaella; Krouskop, Thomas A.; Ophir, Jonathan</p> <p>2006-10-01</p> <p>The technique of mapping the local axial component of the shear <span class="hlt">strain</span> due to quasi-static axial compression is defined as axial shear <span class="hlt">strain</span> elastography. In this paper, the spatial resolution of axial shear <span class="hlt">strain</span> elastography is investigated through simulations, using an elastically stiff cylindrical lesion embedded in a homogeneously softer background. Resolution was defined as the smallest size of the inclusion for which the <span class="hlt">strain</span> value at the inclusion/background interface was greater than the average of the axial shear <span class="hlt">strain</span> values at the interface and inside the inclusion. The resolution was measured from the axial shear <span class="hlt">strain</span> profile oriented at 45° to the axis of beam propagation, due to the absence of axial shear <span class="hlt">strain</span> along the normal directions. The effects of the ultrasound system parameters such as bandwidth, beamwidth and transducer element pitch along with signal processing parameters such as correlation window length (W) and axial shift (ΔW) on the estimated resolution were investigated. The results show that the resolution (at 45° orientation) is determined by the bandwidth and the beamwidth. However, the upper bound on the resolution is limited by the larger of the beamwidth and the window length, which is scaled inversely to the bandwidth. The results also show that the resolution is proportional to the pitch and not significantly affected by the axial window shift.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26529510','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26529510"><span>Highly Invasive Listeria monocytogenes <span class="hlt">Strains</span> Have Growth and Invasion Advantages in <span class="hlt">Strain</span> Competition.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zilelidou, Evangelia A; Rychli, Kathrin; Manthou, Evanthia; Ciolacu, Luminita; Wagner, Martin; Skandamis, Panagiotis N</p> <p>2015-01-01</p> <p>Multiple Listeria monocytogenes <span class="hlt">strains</span> can be present in the same food sample; moreover, infection with more than one L. monocytogenes <span class="hlt">strain</span> can also occur. In this study we investigated the impact of <span class="hlt">strain</span> competition on the growth and in vitro virulence potential of L. monocytogenes. We identified two strong competitor <span class="hlt">strains</span>, whose growth was not (or only slightly) influenced by the presence of other <span class="hlt">strains</span> and two weak competitor <span class="hlt">strains</span>, which were outcompeted by other <span class="hlt">strains</span>. 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 <span class="hlt">strains</span> showed high invasiveness. Moreover, invasion efficiency of the highly invasive <span class="hlt">strain</span> was further increased in certain combinations by the presence of a low invasive <span class="hlt">strain</span>. In all tested combinations, the less invasive <span class="hlt">strain</span> was outcompeted by the higher invasive <span class="hlt">strain</span>. 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 <span class="hlt">strains</span> of the same species leading potentially to biased recovery during enrichment procedures. Furthermore, the presence of more than one L. monocytogenes <span class="hlt">strain</span> in food can lead to increased infection rates due to synergistic effects on the virulence potential.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4631365','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4631365"><span>Highly Invasive Listeria monocytogenes <span class="hlt">Strains</span> Have Growth and Invasion Advantages in <span class="hlt">Strain</span> Competition</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Manthou, Evanthia; Ciolacu, Luminita; Wagner, Martin; Skandamis, Panagiotis N.</p> <p>2015-01-01</p> <p>Multiple Listeria monocytogenes <span class="hlt">strains</span> can be present in the same food sample; moreover, infection with more than one L. monocytogenes <span class="hlt">strain</span> can also occur. In this study we investigated the impact of <span class="hlt">strain</span> competition on the growth and in vitro virulence potential of L. monocytogenes. We identified two strong competitor <span class="hlt">strains</span>, whose growth was not (or only slightly) influenced by the presence of other <span class="hlt">strains</span> and two weak competitor <span class="hlt">strains</span>, which were outcompeted by other <span class="hlt">strains</span>. 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 <span class="hlt">strains</span> showed high invasiveness. Moreover, invasion efficiency of the highly invasive <span class="hlt">strain</span> was further increased in certain combinations by the presence of a low invasive <span class="hlt">strain</span>. In all tested combinations, the less invasive <span class="hlt">strain</span> was outcompeted by the higher invasive <span class="hlt">strain</span>. 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 <span class="hlt">strains</span> of the same species leading potentially to biased recovery during enrichment procedures. Furthermore, the presence of more than one L. monocytogenes <span class="hlt">strain</span> in food can lead to increased infection rates due to synergistic effects on the virulence potential. PMID:26529510</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRB..121.5736Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRB..121.5736Q"><span>Heterogeneity of inelastic <span class="hlt">strain</span> during creep of Carrara marble: Microscale <span class="hlt">strain</span> measurement technique</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Quintanilla-Terminel, Alejandra; Evans, Brian</p> <p>2016-08-01</p> <p>We combined the split cylinder technique with microfabrication technology to observe <span class="hlt">strain</span> 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 <span class="hlt">strain</span> measurement (MSSM) technique described here allowed us to analyze the local <span class="hlt">strain</span> distribution with unprecedented detail over large regions. The description of the <span class="hlt">strain</span> field is a function of the area over which <span class="hlt">strain</span> is being computed. The scale at which the <span class="hlt">strain</span> 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 <span class="hlt">strained</span> bands that span several grains. One possible cause for the multigrain bands is the need to relieve <span class="hlt">strain</span> incompatibilities that result when twins impinge on neighboring grains. At 600-700°C, the <span class="hlt">strain</span> fields are still quite heterogeneous, and local <span class="hlt">strain</span> 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 <span class="hlt">strain</span> 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 <span class="hlt">strains</span> normalized by the total <span class="hlt">strain</span>; thus, we conclude that the microstructure does not achieve a steady state in this <span class="hlt">strain</span> interval.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10888638','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10888638"><span>Genetic diversity among Lassa virus <span class="hlt">strains</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bowen, M D; Rollin, P E; Ksiazek, T G; Hustad, H L; Bausch, D G; Demby, A H; Bajani, M D; Peters, C J; Nichol, S T</p> <p>2000-08-01</p> <p>The arenavirus Lassa virus causes Lassa fever, a viral hemorrhagic fever that is endemic in the countries of Nigeria, Sierra Leone, Liberia, and Guinea and perhaps elsewhere in West Africa. To determine the degree of genetic diversity among Lassa virus <span class="hlt">strains</span>, partial nucleoprotein (NP) gene sequences were obtained from 54 <span class="hlt">strains</span> and analyzed. Phylogenetic analyses showed that Lassa viruses comprise four lineages, three of which are found in Nigeria and the fourth in Guinea, Liberia, and Sierra Leone. Overall <span class="hlt">strain</span> variation in the partial NP gene sequence was found to be as high as 27% at the nucleotide level and 15% at the amino acid level. Genetic distance among Lassa <span class="hlt">strains</span> was found to correlate with geographic distance rather than time, and no evidence of a "molecular clock" was found. A method for amplifying and cloning full-length arenavirus S RNAs was developed and used to obtain the complete NP and glycoprotein gene (GP1 and GP2) sequences for two representative Nigerian <span class="hlt">strains</span> of Lassa virus. Comparison of full-length gene sequences for four Lassa virus <span class="hlt">strains</span> representing the four lineages showed that the NP gene (up to 23.8% nucleotide difference and 12.0% amino acid difference) is more variable than the glycoprotein genes. Although the evolutionary order of descent within Lassa virus <span class="hlt">strains</span> was not completely resolved, the phylogenetic analyses of full-length NP, GP1, and GP2 gene sequences suggested that Nigerian <span class="hlt">strains</span> of Lassa virus were ancestral to <span class="hlt">strains</span> from Guinea, Liberia, and Sierra Leone. Compared to the New World arenaviruses, Lassa and the other Old World arenaviruses have either undergone a shorter period of diverisification or are evolving at a slower rate. This study represents the first large-scale examination of Lassa virus genetic variation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003AGUFM.V12A0552Q','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003AGUFM.V12A0552Q"><span>Microstructural Analysis of Welding: Deformation and <span class="hlt">Strain</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Quane, S. L.; Russell, K.</p> <p>2003-12-01</p> <p>Welding in pyroclastic deposits involves the sintering, compaction and flattening of hot glassy particles and is attended by systematic changes in physical properties. Welded materials contain implicit information regarding the total accumulated <span class="hlt">strain</span> as well as the mechanisms of deformation. Here, we use detailed microstructural analysis of synthetic and natural welded materials to make quantitative estimates of <span class="hlt">strain</span> and constrain the rheology of these materials during the welding process. Part one of our study comprises microstructural analysis of end products from unconfined high temperature deformation experiments on sintered cores of soda-lime silica glass spheres. This analogue material has relatively simple and well-characterized starting properties. Furthermore, the initially spherical shapes of particles provide excellent <span class="hlt">strain</span> markers. Experiments were run at a variety of temperatures, <span class="hlt">strain</span> rates and stresses resulting in end products with varying degrees of total <span class="hlt">strain</span>. The nature of <span class="hlt">strain</span> partitioning and accumulation are evaluated using image analysis techniques on scanned images and photomicrographs of thin sections cut perpendicular to the loading direction of each experimental product. Shapes of the individual deformed particles (e.g., oblate spheroids) were determined and the Scion image analysis program was used to create a best-fit ellipse for each particle. Statistics collected on each particle include: axial dimension (a), vertical dimension (c) and angle from the horizontal. The data are used to calculate the oblateness of each particle (1-c/a) and the angle of deformation induced foliation. Furthermore, the relative proportions of visible blue epoxy in the sample scans determine bulk porosity. The average oblateness of the particles is a direct, independent measure of the accumulated <span class="hlt">strain</span> in each sample. Results indicate that these measured values are equal to calculated theoretical values of oblateness for spheroids undergoing the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/6239469','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/6239469"><span>Differentiation of pathogenic and saprophytic leptospira <span class="hlt">strains</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bazovská, S; Kmety, E; Rak, J</p> <p>1984-09-01</p> <p>Comparative studies of 249 pathogenic and 80 saprophytic leptospira <span class="hlt">strains</span>, including 2 <span class="hlt">strains</span> 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 <span class="hlt">strain</span> of the illini type was recognized.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21506808','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21506808"><span><span class="hlt">Strain</span> Determination Using Electron Backscatter Diffraction</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Krause, M.; Graff, A.; Altmann, F.</p> <p>2010-11-24</p> <p>In the present paper we demonstrate the use of electron backscatter diffraction (EBSD) for high resolution elastic <span class="hlt">strain</span> determination. Here, we focus on analysis methods based on determination of small shifts in EBSD pattern with respect to a reference pattern using cross-correlation algorithms. Additionally we highlight the excellent spatial and depth resolution of EBSD and introduce the use of simulated diffraction patterns based on dynamical diffraction theory for sensitivity estimation. Moreover the potential of EBSD for <span class="hlt">strain</span> analysis of <span class="hlt">strained</span> thin films with particular emphasis on appropriate target preparation which respect to occurring lattice defects is demonstrated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10543843','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10543843"><span>Genotypic diversity among Brevibacillus laterosporus <span class="hlt">strains</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zahner, V; Rabinovitch, L; Suffys, P; Momen, H</p> <p>1999-11-01</p> <p>In comparison with other entomopathogenic Bacillus species, the genome of Brevibacillus laterosporus is poorly characterized. The aim of this study was to examine genetic variability in B. laterosporus by using a range of typing methodologies. <span class="hlt">Strains</span> of B. laterosporus were examined for variation in 13 chromosomal genes encoding enzymes by multilocus enzyme electrophoresis. Optimal conditions of pulsed-field gel electrophoresis and randomly amplified polymorphic DNA were established that allowed analysis of the genome of B. laterosporus. None of these techniques allowed the identification of a convenient molecular marker for entomopathogenic <span class="hlt">strains</span>, although one specific primer amplified only DNA from almost all mosquitocidal <span class="hlt">strains</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25384695','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25384695"><span>Bioleaching of multiple heavy metals from contaminated sediment by mesophile consortium.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gan, Min; Zhou, Shuang; Li, Mingming; Zhu, Jianyu; Liu, Xinxing; Chai, Liyuan</p> <p>2015-04-01</p> <p>A defined mesophile consortium including <span class="hlt">Acidithiobacillus</span> <span class="hlt">ferrooxidans</span>, <span class="hlt">Acidithiobacillus</span> thiooxidans, and Leptospirilum ferriphilum was applied in bioleaching sediments contaminated with multiple heavy metals. Flask experiments showed that sulfur favored the acidification in the early stage while pyrite led to a great acidification potential in the later stage. An equal sulfur/pyrite ratio got the best acidification effect. Substrate utilization started with sulfur in the early stage, and then the pH decline and the community shift give rise to the utilization of pyrite. Solubilization efficiency of Zn, Cu, Mn, and Cd reached 96.1, 93.3, 92.13, and 87.65%, respectively. Bioleaching efficiency of other elements (As, Hg, Pb) was not more than 30%. Heavy metal solubilization was highly negatively correlated with pH variation. Logistic models were well fitted with the solubilization efficiency, which can be used to predict the bioleaching process. The dominant species in the early stage of bioleaching were A. <span class="hlt">ferrooxidans</span> and A. thiooxidans, and the abundance of L. ferriphilum increased together with pyrite utilization and pH decline.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27351900','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27351900"><span>Sequential biological process for molybdenum extraction from hydrodesulphurization spent catalyst.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Vyas, Shruti; Ting, Yen-Peng</p> <p>2016-10-01</p> <p>Spent catalyst bioleaching with <span class="hlt">Acidithiobacillus</span> <span class="hlt">ferrooxidans</span> has been widely studied and low Mo leaching has often been reported. This work describes an enhanced extraction of Mo via a two stage sequential process for the bioleaching of hydrodesulphurization spent catalyst containing Molybdenum, Nickel and, Aluminium. In the first stage, two-step bioleaching was performed using <span class="hlt">Acidithiobacillus</span> <span class="hlt">ferrooxidans</span>, and achieved 89.4% Ni, 20.9% Mo and 12.7% Al extraction in 15 days. To increase Mo extraction, the bioleached catalyst was subjected to a second stage bioleaching using Escherichia coli, during which 99% of the remaining Mo was extracted in 25 days. This sequential bioleaching strategy selectively extracted Ni in the first stage and Mo in the second stage, and is a more environmentally friendly alternative to sequential chemical leaching with alkaline reagents for improved Mo extraction. Kinetic modelling to establish the rate determining step in both stages of bioleaching showed that in the first stage, Mo extraction was chemical reaction controlled whereas in the subsequent stage, product layer diffusion model provided the best fit.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3815317','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3815317"><span>Dynamic of active microorganisms inhabiting a bioleaching industrial heap of low‐grade copper sulfide ore monitored by real‐time PCR and oligonucleotide prokaryotic acidophile microarray</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Remonsellez, Francisco; Galleguillos, Felipe; Moreno‐Paz, Mercedes; Parro, Víctor; Acosta, Mauricio; Demergasso, Cecilia</p> <p>2009-01-01</p> <p>Summary The bioleaching of metal sulfide has developed into a very important industrial process and understanding the microbial dynamic is key to advancing commercial bioleaching operations. Here we report the first quantitative description of the dynamic of active communities in an industrial bioleaching heap. <span class="hlt">Acidithiobacillus</span> <span class="hlt">ferrooxidans</span> was the most abundant during the first part of the leaching cycle, while the abundance of Leptospirillum ferriphilum and Ferroplasma acidiphilum increased with age of the heap. <span class="hlt">Acidithiobacillus</span> thiooxidans kept constant throughout the leaching cycle, and Firmicutes group showed a low and a patchy distribution in the heap. The Acidiphilium‐like bacteria reached their highest abundance corresponding to the amount of autotrophs. The active microorganisms in the leaching system were determined using two RNA‐based sensitive techniques. In most cases, the 16S rRNA copy numbers of At. <span class="hlt">ferrooxidans</span>, L. ferriphilum, At. thiooxidans and F. acidiphilum, was concomitant with the DNA copy numbers, whereas Acidiphilium‐like bacteria and some Firmicutes members did not show a clear correlation between 16S rRNA accumulation and DNA copy numbers. However, the prokaryotic acidophile microarray (PAM) analysis showed active members of Alphaproteobacteria in all samples and of Sulfobacillus genus in older ones. Also, new active groups such as Actinobacteria and Acidobacterium genus were detected by PAM. The results suggest that changes during the leaching cycle in chemical and physical conditions, such as pH and Fe3+/Fe2+ ion rate, are primary factors shaping the microbial dynamic in the heap. PMID:21255296</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2014-title40-vol24/pdf/CFR-2014-title40-vol24-sec180-1209.pdf','CFR2014'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2014-title40-vol24/pdf/CFR-2014-title40-vol24-sec180-1209.pdf"><span>40 CFR 180.1209 - Bacillus subtilis <span class="hlt">strain</span> QST 713 and <span class="hlt">strain</span> QST 713 variant soil; exemption from the requirement...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2014&page.go=Go">Code of Federal Regulations, 2014 CFR</a></p> <p></p> <p>2014-07-01</p> <p>... <span class="hlt">strain</span> QST 713 variant soil; exemption from the requirement of a tolerance. 180.1209 Section 180.1209... <span class="hlt">strain</span> QST 713 and <span class="hlt">strain</span> QST 713 variant soil; exemption from the requirement of a tolerance. An... Bacillus subtilis <span class="hlt">strain</span> QST 713 and <span class="hlt">strain</span> QST 713 variant soil when used in or on all food commodities....</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.gpo.gov/fdsys/pkg/CFR-2013-title40-vol25/pdf/CFR-2013-title40-vol25-sec180-1209.pdf','CFR2013'); return false;" href="https://www.gpo.gov/fdsys/pkg/CFR-2013-title40-vol25/pdf/CFR-2013-title40-vol25-sec180-1209.pdf"><span>40 CFR 180.1209 - Bacillus subtilis <span class="hlt">strain</span> QST 713 and <span class="hlt">strain</span> QST 713 variant soil; exemption from the requirement...</span></a></p> <p><a target="_blank" href="http://www.gpo.gov/fdsys/browse/collectionCfr.action?selectedYearFrom=2013&page.go=Go">Code of Federal Regulations, 2013 CFR</a></p> <p></p> <p>2013-07-01</p> <p>... <span class="hlt">strain</span> QST 713 variant soil; exemption from the requirement of a tolerance. 180.1209 Section 180.1209... <span class="hlt">strain</span> QST 713 and <span class="hlt">strain</span> QST 713 variant soil; exemption from the requirement of a tolerance. An... Bacillus subtilis <span class="hlt">strain</span> QST 713 and <span class="hlt">strain</span> QST 713 variant soil when used in or on all food commodities....</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014SPIE.9040E..15Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014SPIE.9040E..15Y"><span>A new radial <span class="hlt">strain</span> and <span class="hlt">strain</span> rate estimation method using autocorrelation for carotid artery</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ye, Jihui; Kim, Hoonmin; Park, Jongho; Yeo, Sunmi; Shim, Hwan; Lim, Hyungjoon; Yoo, Yangmo</p> <p>2014-03-01</p> <p>Atherosclerosis is a leading cause of cardiovascular disease. The early diagnosis of atherosclerosis is of clinical interest since it can prevent any adverse effects of atherosclerotic vascular diseases. In this paper, a new carotid artery radial <span class="hlt">strain</span> estimation method based on autocorrelation is presented. In the proposed method, the <span class="hlt">strain</span> is first estimated by the autocorrelation of two complex signals from the consecutive frames. Then, the angular phase from autocorrelation is converted to <span class="hlt">strain</span> and <span class="hlt">strain</span> rate and they are analyzed over time. In addition, a 2D <span class="hlt">strain</span> image over region of interest in a carotid artery can be displayed. To evaluate the feasibility of the proposed radial <span class="hlt">strain</span> estimation method, radiofrequency (RF) data of 408 frames in the carotid artery of a volunteer were acquired by a commercial ultrasound system equipped with a research package (V10, Samsung Medison, Korea) by using a L5-13IS linear array transducer. From in vivo carotid artery data, the mean <span class="hlt">strain</span> estimate was -0.1372 while its minimum and maximum values were -2.961 and 0.909, respectively. Moreover, the overall <span class="hlt">strain</span> estimates are highly correlated with the reconstructed M-mode trace. Similar results were obtained from the estimation of the <span class="hlt">strain</span> rate change over time. These results indicate that the proposed carotid artery radial <span class="hlt">strain</span> estimation method is useful for assessing the arterial wall's stiffness noninvasively without increasing the computational complexity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25769835','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25769835"><span>Tropical <span class="hlt">strains</span> of Ralstonia solanacearum Outcompete race 3 biovar 2 <span class="hlt">strains</span> at lowland tropical temperatures.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Huerta, Alejandra I; Milling, Annett; Allen, Caitilyn</p> <p>2015-05-15</p> <p>Bacterial wilt, caused by members of the heterogenous Ralstonia solanacearum species complex, is an economically important vascular disease affecting many crops. Human activity has widely disseminated R. solanacearum <span class="hlt">strains</span>, increasing their global agricultural impact. However, tropical highland race 3 biovar 2 (R3bv2) <span class="hlt">strains</span> do not cause disease in tropical lowlands, even though they are virulent at warm temperatures. We tested the hypothesis that differences in temperature adaptation and competitive fitness explain the uneven geographic distribution of R. solanacearum <span class="hlt">strains</span>. Using three phylogenetically and ecologically distinct <span class="hlt">strains</span>, we measured competitive fitness at two temperatures following paired-<span class="hlt">strain</span> inoculations of their shared host, tomato. Lowland tropical <span class="hlt">strain</span> GMI1000 was only weakly virulent on tomato under temperate conditions (24°C for day and 19°C for night [24/19°C]), but highland tropical R3bv2 <span class="hlt">strain</span> UW551 and U.S. warm temperate <span class="hlt">strain</span> K60 were highly virulent at both 24/19°C and 28°C. <span class="hlt">Strain</span> K60 was significantly more competitive than both GMI1000 and UW551 in tomato rhizospheres and stems at 28°C, and GMI1000 also outcompeted UW551 at 28°C. The results were reversed at cooler temperatures, at which highland <span class="hlt">strain</span> UW551 generally outcompeted GMI1000 and K60 in planta. The superior competitive index of UW551 at 24/19°C suggests that adaptation to cool temperatures could explain why only R3bv2 <span class="hlt">strains</span> threaten highland agriculture. <span class="hlt">Strains</span> K60 and GMI1000 each produced different bacteriocins that inhibited growth of UW551 in culture. Such interstrain inhibition could explain why R3bv2 <span class="hlt">strains</span> do not cause disease in tropical lowlands.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4407210','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4407210"><span>Tropical <span class="hlt">Strains</span> of Ralstonia solanacearum Outcompete Race 3 Biovar 2 <span class="hlt">Strains</span> at Lowland Tropical Temperatures</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Huerta, Alejandra I.; Milling, Annett</p> <p>2015-01-01</p> <p>Bacterial wilt, caused by members of the heterogenous Ralstonia solanacearum species complex, is an economically important vascular disease affecting many crops. Human activity has widely disseminated R. solanacearum <span class="hlt">strains</span>, increasing their global agricultural impact. However, tropical highland race 3 biovar 2 (R3bv2) <span class="hlt">strains</span> do not cause disease in tropical lowlands, even though they are virulent at warm temperatures. We tested the hypothesis that differences in temperature adaptation and competitive fitness explain the uneven geographic distribution of R. solanacearum <span class="hlt">strains</span>. Using three phylogenetically and ecologically distinct <span class="hlt">strains</span>, we measured competitive fitness at two temperatures following paired-<span class="hlt">strain</span> inoculations of their shared host, tomato. Lowland tropical <span class="hlt">strain</span> GMI1000 was only weakly virulent on tomato under temperate conditions (24°C for day and 19°C for night [24/19°C]), but highland tropical R3bv2 <span class="hlt">strain</span> UW551 and U.S. warm temperate <span class="hlt">strain</span> K60 were highly virulent at both 24/19°C and 28°C. <span class="hlt">Strain</span> K60 was significantly more competitive than both GMI1000 and UW551 in tomato rhizospheres and stems at 28°C, and GMI1000 also outcompeted UW551 at 28°C. The results were reversed at cooler temperatures, at which highland <span class="hlt">strain</span> UW551 generally outcompeted GMI1000 and K60 in planta. The superior competitive index of UW551 at 24/19°C suggests that adaptation to cool temperatures could explain why only R3bv2 <span class="hlt">strains</span> threaten highland agriculture. <span class="hlt">Strains</span> K60 and GMI1000 each produced different bacteriocins that inhibited growth of UW551 in culture. Such interstrain inhibition could explain why R3bv2 <span class="hlt">strains</span> do not cause disease in tropical lowlands. PMID:25769835</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004SPIE.5373..173T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004SPIE.5373..173T"><span>Simultaneous narrowband ultrasonic <span class="hlt">strain</span>-flow imaging</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tsou, Jean K.; Mai, Jerome J.; Lupotti, Fermin A.; Insana, Michael F.</p> <p>2004-04-01</p> <p>We are summarizing new research aimed at forming spatially and temporally registered combinations of <span class="hlt">strain</span> and color-flow images using echo data recorded from a commercial ultrasound system. Applications include diagnosis of vascular diseases and tumor malignancies. The challenge is to meet the diverse needs of each measurement. The approach is to first apply eigenfilters that separate echo components from moving tissues and blood flow, and then estimate blood velocity and tissue displacement from the filtered-IQ-signal phase modulations. At the cost of a lower acquisition frame rate, we find the autocorrelation <span class="hlt">strain</span> estimator yields higher resolution <span class="hlt">strain</span> estimate than the cross-correlator since estimates are made from ensembles at a single point in space. The technique is applied to in vivo carotid imaging, to demonstrate the sensitivity for <span class="hlt">strain</span>-flow vascular imaging.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://kidshealth.org/en/parents/broken-bones.html','NIH-MEDLINEPLUS'); return false;" href="https://kidshealth.org/en/parents/broken-bones.html"><span>Broken Bones, Sprains, and <span class="hlt">Strains</span> (For Parents)</span></a></p> <p><a target="_blank" href="http://medlineplus.gov/">MedlinePlus</a></p> <p></p> <p></p> <p>... Feeding Your 1- to 2-Year-Old Broken Bones, Sprains, and <span class="hlt">Strains</span> KidsHealth > For Parents > Broken Bones, ... home. What to Do: For a Suspected Broken Bone: Do not move a child whose injury involves ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ApPhL.107s3102G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ApPhL.107s3102G"><span>Tuning <span class="hlt">strain</span> in flexible graphene nanoelectromechanical resonators</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guan, Fen; Kumaravadivel, Piranavan; Averin, Dmitri V.; Du, Xu</p> <p>2015-11-01</p> <p>The structural flexibility of low dimensional nanomaterials offers unique opportunities for studying the impact of <span class="hlt">strain</span> on their physical properties and for developing innovative devices utilizing <span class="hlt">strain</span> engineering. A key towards such goals is a device platform which allows the independent tuning and reliable calibration of the <span class="hlt">strain</span>. Here, we report the fabrication and characterization of graphene nanoelectromechanical resonators (GNEMRs) on flexible substrates. Combining substrate bending and electrostatic gating, we achieve the independent tuning of the <span class="hlt">strain</span> and sagging in graphene and explore the nonlinear dynamics over a wide parameter space. Analytical and numerical studies of a continuum mechanics model, including the competing higher order nonlinear terms, reveal a comprehensive nonlinear dynamics phase diagram, which quantitatively explains the complex behaviors of GNEMRs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=243113','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=243113"><span>Carotene-superproducing <span class="hlt">strains</span> of Phycomyces.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Murillo, F J; Calderón, I L; López-Díaz, I; Cerdá-Olmedo, E</p> <p>1978-01-01</p> <p>Production of beta-carotene by wild-type Phycomyces blakesleeanus can be stimulated by light, chemicals, regulatory mutations, and sexual interaction between mycelia of opposite sex. Through genetic manipulations, we have isolated <span class="hlt">strains</span> which have simultaneously and constitutively incorporated several of these stimulatory effects. In the dark and in a simple medium, some of the <span class="hlt">strains</span> produce up to 25 mg of beta-carotene per g (dry weight), or about 500 times the wild-type production under the same conditions. High lycopene-producing <span class="hlt">strains</span> have also been isolated by using carR mutants, which are blocked in the conversion of lycopene to beta-carotene. These <span class="hlt">strains</span> should be useful in both industrial production of these pigments and basic research related to carotenogenesis. PMID:727783</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940008401','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940008401"><span><span class="hlt">Strain</span> sensing technology for high temperature applications</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Williams, W. Dan</p> <p>1993-01-01</p> <p>This review discusses the status of <span class="hlt">strain</span> sensing technology for high temperature applications. Technologies covered are those supported by NASA such as required for applications in hypersonic vehicles and engines, advanced subsonic engines, as well as material and structure development. The applications may be at temperatures of 540 C (1000 F) to temperatures in excess of 1400 C (2500 F). The most promising technologies at present are the resistance <span class="hlt">strain</span> gage and remote sensing schemes. Resistance <span class="hlt">strain</span> gages discussed include the BCL gage, the LaRC compensated gage, and the PdCr gage. Remote sensing schemes such as laser based speckle <span class="hlt">strain</span> measurement, phase-shifling interferometry, and x-ray extensometry are discussed. Present status and limitations of these technologies are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..MARZ39008B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..MARZ39008B"><span>Can a <span class="hlt">strain</span> yield a qubit?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Benjamin, Colin</p> <p>2015-03-01</p> <p>A Josepshon qubit is designed via the application of a tensile <span class="hlt">strain</span> to a topological insulator surface, sandwiched between two s-wave superconductors. The <span class="hlt">strain</span> applied leads to a shift in Dirac point without changing the conducting states existing on the surface of a topological insulator. This <span class="hlt">strain</span> applied can be tuned to form a π-junction in such a structure. Combining two such junctions in a ring architecture leads to the ground state of the ring being in a doubly degenerate state- ``0'' and ``1'' states of the qubit. A qubit designed this way is easily controlled via the tunable <span class="hlt">strain</span>. We report on the conditions necessary to design such a qubit. Finally the operating time of a single qubit phase gate is derived. This work was supported by funds from Dept. of Science and Technology (Nanomission), Govt. of India, Grant No. SR/NM/NS-1101/2011.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25817029','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25817029"><span>Survival and activity of individual bioaugmentation <span class="hlt">strains</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dueholm, Morten S; Marques, Irina G; Karst, Søren M; D'Imperio, Seth; Tale, Vaibhav P; Lewis, Derrick; Nielsen, Per Halkjær; Nielsen, Jeppe Lund</p> <p>2015-06-01</p> <p>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 <span class="hlt">strains</span>. 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 <span class="hlt">strains</span> 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 <span class="hlt">strains</span> directly in samples, all in combination with removal studies of the target compounds. The concept of the approach is demonstrated through a case study involving degradation of aromatic hydrocarbons in activated sludge augmented with the bioaugmentation <span class="hlt">strain</span> Pseudomonas monteilii SB3078.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050163141','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050163141"><span><span class="hlt">Strained</span> Hydrocarbons as Potential Hypergolic Fuels</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p></p> <p>2005-01-01</p> <p>A storable combination of high-energy hypergolic fuel and oxidizer is advantageous to the future of reusable launch vehicles (RLVs). The combination will allow an increase in energy per unit volume of fuel and eliminate the need for an external ignition system. <span class="hlt">Strained</span> systems have been studied as potential high-density fuels. Adding hypergolic functional groups, such as amino groups, to these hydrocarbons will potentially allow auto ignition of <span class="hlt">strained</span> systems with hydrogen peroxide. Several straight chain amines and their <span class="hlt">strained</span> counterparts containing an equivalent number of carbon atoms have been purchased and synthesized. These amines provide initial studies to determine the effects of fuel vapor pressure, <span class="hlt">strain</span> energy, fuel miscibility, and amine substitution upon fuel ignition time and hypergolicity with hydrogen peroxide as an oxidizer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=strain+AND+gauges&id=EJ095175','ERIC'); return false;" href="http://eric.ed.gov/?q=strain+AND+gauges&id=EJ095175"><span>Dynamic Force Measurement with <span class="hlt">Strain</span> Gauges</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Lee, Bruce E.</p> <p>1974-01-01</p> <p>Discusses the use of four <span class="hlt">strain</span> gauges, a Wheatstone bridge, and an oscilloscope to measure forces dynamically. Included is an example of determining the centripetal force of a pendulum in a general physics laboratory. (CC)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870019450','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870019450"><span>Thin film <span class="hlt">strain</span> gage development program</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Grant, H. P.; Przybyszewski, J. S.; Anderson, W. L.; Claing, R. G.</p> <p>1983-01-01</p> <p>Sputtered thin-film dynamic <span class="hlt">strain</span> gages of 2 millimeter (0.08 in) gage length and 10 micrometer (0.0004 in) thickness were fabricated on turbojet engine blades and tested in a simulated compressor environment. Four designs were developed, two for service to 600 K (600 F) and two for service to 900 K (1200 F). The program included a detailed study of guidelines for formulating <span class="hlt">strain</span>-gage alloys to achieve superior dynamic and static gage performance. The tests included gage factor, fatigue, temperature cycling, spin to 100,000 G, and erosion. Since the installations are 30 times thinner than conventional wire <span class="hlt">strain</span> gage installations, and any alteration of the aerodynamic, thermal, or structural performance of the blade is correspondingly reduced, dynamic <span class="hlt">strain</span> measurement accuracy higher than that attained with conventional gages is expected. The low profile and good adherence of the thin film elements is expected to result in improved durability over conventional gage elements in engine tests.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1013558','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1013558"><span>Method of transferring <span class="hlt">strained</span> semiconductor structure</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Nastasi, Michael A.; Shao, Lin</p> <p>2009-12-29</p> <p>The transfer of <span class="hlt">strained</span> semiconductor layers from one substrate to another substrate involves depositing a multilayer structure on a substrate having surface contaminants. An interface that includes the contaminants is formed in between the deposited layer and the substrate. Hydrogen atoms are introduced into the structure and allowed to diffuse to the interface. Afterward, the deposited multilayer structure is bonded to a second substrate and is separated away at the interface, which results in transferring a multilayer structure from one substrate to the other substrate. The multilayer structure includes at least one <span class="hlt">strained</span> semiconductor layer and at least one <span class="hlt">strain</span>-induced seed layer. The <span class="hlt">strain</span>-induced seed layer can be optionally etched away after the layer transfer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19820059659&hterms=Durbin&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DDurbin','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19820059659&hterms=Durbin&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DDurbin"><span>The premixed flame in uniform <span class="hlt">straining</span> flow</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Durbin, P. A.</p> <p>1982-01-01</p> <p>Characteristics of the premixed flame in uniform <span class="hlt">straining</span> flow are investigated by the technique of activation-energy asymptotics. An inverse method is used, which avoids some of the restrictions of previous analyses. It is shown that this method recovers known results for adiabatic flames. New results for flames with heat loss are obtained, and it is shown that, in the presence of finite heat loss, <span class="hlt">straining</span> can extinguish flames. A stability analysis shows that <span class="hlt">straining</span> can suppress the cellular instability of flames with Lewis number less than unity. <span class="hlt">Strain</span> can produce instability of flames with Lewis number greater than unity. A comparison shows quite good agreement between theoretical deductions and experimental observations of Ishizuka, Miyasaka & Law (1981).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21882791','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21882791"><span>Heat <span class="hlt">strain</span> during explosive ordnance disposal.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Stewart, Ian B; Rojek, Amanda M; Hunt, Andrew P</p> <p>2011-08-01</p> <p>Bomb technicians perform their work while encapsulated in explosive ordnance disposal suits. Designed primarily for safety, these suits have an unintended consequence of impairing the body's natural mechanisms for heat dissipation. Consequently, bomb technicians are known to experience symptoms of heat illness while performing their work. This research provides the first field based analysis of heat <span class="hlt">strain</span> in bomb technicians. Six participants undertook simulated operational tasks across 2 days of variable climate. All subjects demonstrated high levels of heat <span class="hlt">strain</span> as evidenced by elevated heart rate, core body temperature, and physiological <span class="hlt">strain</span> index. Participants also reported signs and symptoms associated with heat illness. These results were exacerbated by more intense physical activity despite being undertaken in a cooler environment. The universal experience of heat <span class="hlt">strain</span> in this sample has significant implications for the health of bomb technicians and additional research examining methods to improve temperature regulation and performance is warranted.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013NaPho...7...86L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013NaPho...7...86L"><span>Optical physics: Magnetic appeal in <span class="hlt">strained</span> lattice</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lepetit, Thomas</p> <p>2013-02-01</p> <p>Using <span class="hlt">strain</span> to induce a pseudomagnetic field in a photonic lattice at optical frequencies might bring improvements to fields such as photonic crystal fibres, supercontinuum generation and frequency combs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930081520','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930081520"><span>The Development of Electrical <span class="hlt">Strain</span> Gages</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>De Forest, A V; Leaderman, H</p> <p>1940-01-01</p> <p>The design, construction, and properties of an electrical-resistance <span class="hlt">strain</span> gage consisting of fine wires molded in a laminated plastic are described. The properties of such gages are discussed and also the problems of molding of wires in plastic materials, temperature compensation, and cementing and removal of the gages. Further work to be carried out on the <span class="hlt">strain</span> gage, together with instrument problems, is discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20050179347&hterms=Adhesives&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DAdhesives','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20050179347&hterms=Adhesives&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DAdhesives"><span>High-Temperature Adhesive <span class="hlt">Strain</span> Gage Developed</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pereira, J. Michael; Roberts, Gary D.</p> <p>1997-01-01</p> <p>Researchers at the NASA Lewis Research Center have developed a unique <span class="hlt">strain</span> gage and adhesive system for measuring the mechanical properties of polymers and polymer composites at elevated temperatures. This system overcomes some of the problems encountered in using commercial <span class="hlt">strain</span> gages and adhesives. For example, typical commercial <span class="hlt">strain</span> gage adhesives require a postcure at temperatures substantially higher than the maximum test temperature. The exposure of the specimen to this temperature may affect subsequent results, and in some cases may be higher than the glass-transition temperature of the polymer. In addition, although typical commercial <span class="hlt">strain</span> gages can be used for short times at temperatures up to 370 C, their long-term use is limited to 230 C. This precludes their use for testing some high-temperature polyimides near their maximum temperature capability. Lewis' <span class="hlt">strain</span> gage and adhesive system consists of a nonencapsulated, unbacked gage grid that is bonded directly to the polymer after the specimen has been cured but prior to the normal postcure cycle. The gage is applied with an adhesive specially formulated to cure under the specimen postcure conditions. Special handling, mounting, and electrical connection procedures were developed, and a fixture was designed to calibrate each <span class="hlt">strain</span> gage after it was applied to a specimen. A variety of tests was conducted to determine the performance characteristics of the gages at elevated temperatures on PMR-15 neat resin and titanium specimens. For these tests, which included static tension, thermal exposure, and creep tests, the gage and adhesive system performed within normal <span class="hlt">strain</span> gage specifications at 315 C. An example of the performance characteristics of the gage can be seen in the figure, which compares the <span class="hlt">strain</span> gage measurement on a polyimide specimen at 315 C with an extensometer measurement.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3647418','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3647418"><span>Feline Origin of Rotavirus <span class="hlt">Strain</span>, Tunisia, 2008</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Fredj, Mouna Ben Hadj; Heylen, Elisabeth; Zeller, Mark; Fodha, Imene; Benhamida-Rebai, Meriam; Van Ranst, Marc; Matthijnssens, Jelle</p> <p>2013-01-01</p> <p>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 <span class="hlt">strain</span>, we conducted phylogenetic analyses and found a unique genotype constellation resembling rotaviruses belonging to the feline BA222-like genotype constellation. The <span class="hlt">strain</span> probably resulted from direct cat-to-human transmission. PMID:23631866</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/10161061','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/10161061"><span>Thermographic phosphor <span class="hlt">strain</span> measurements. Final report</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Allison, S.W.; Capps, G.J.; Smith, D.B.; Cates, M.R.; Gleason, J.; Turley, W.D.</p> <p>1994-05-01</p> <p>This report describes the first phase of research aimed at developing a high-temperature <span class="hlt">strain</span> gauge for power equipment use based on materials whose fluorescence characteristics are affected by <span class="hlt">strain</span>. In electric power generating plants, the combined effect of temperature and <span class="hlt">strain</span> on equipment and structures is a critical factor in safe, efficient operation and component lifetime. For the first part of this project, the pressure responses of phosphor and crystalline materials were surveyed. Next, pressure measurements on some promising materials, YVO{sub 4}:Dy and Gd{sub 2}O{sub 2}S:Tb, were performed. The latter phosphor appears to exhibit the greatest change with pressure. Its fluorescence lifetime decreases by a factor of 10 with pressure increase of 20 kbar. In a <span class="hlt">strain</span> test configuration, a tapered sapphire rod compressed a similar phosphor material, La{sub 2}O{sub 2}S:Eu. The intensity level increased, as expected for this material, with compression. Both of the oxysulfide materials possess potential for use in an optical <span class="hlt">strain</span> gauge for temperatures up to at least 300{degrees}C. It is suggested that a mixture of these two materials may be a useful way to obtain the maximum pressure or <span class="hlt">strain</span> sensitivity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008AGUFM.H43E1060P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008AGUFM.H43E1060P"><span>Colloid <span class="hlt">Straining</span> within Saturated Heterogeneous Porous Media</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Porubcan, A.; Walczak, J.; Xu, S.</p> <p>2008-12-01</p> <p>A thorough understanding of colloid movement in the subsurface system is critical to the assessment of groundwater pollution by pathogenic bacteria and colloid-bound contaminants. It is increasingly recognized that <span class="hlt">straining</span>, a process that occurs when the pore space is too small to allow for a particle's passage, represents an important process in colloid immobilization within groundwater systems. Previously published studies have focused on the kinetics of colloid <span class="hlt">straining</span> within sand packs composed of uniform mineral grains. Natural aquifers, however, are usually characterized by physically heterogeneous sediments. In this study, we conducted column transport experiments with carboxylated latex particles and quartz sand to investigate the impact of sediment texture (i.e., the size distribution of mineral grains) on colloid <span class="hlt">straining</span> kinetics. The quartz sands used in the experiment were thoroughly cleaned and the strong repulsive interactions between colloid particles and quartz sands resulted in minimal physicochemical deposition so the <span class="hlt">straining</span> kinetics can be quantified unambiguously. Sand packs of different textures were prepared by mixing sands of various sizes (mesh sizes of 20-25, 35-40 and 60-70). Our results suggested that the ratio of colloid size and the median sand grain size was insufficient to predict colloid <span class="hlt">straining</span> within heterogeneous sediments. Soil texture, which was related to the size distribution of the sand grains, must be considered. A relationship between colloid <span class="hlt">straining</span> kinetics and the heterogeneity of porous media that can be useful for the prediction of colloid transport within heterogeneous sediments was presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011OptMa..33..408F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011OptMa..33..408F"><span>Flexible photonic crystals for <span class="hlt">strain</span> sensing</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fortes, Luís M.; Gonçalves, M. Clara; Almeida, Rui M.</p> <p>2011-01-01</p> <p>Three-dimensional (3-D) photonic crystals (PCs) have been studied as possible <span class="hlt">strain</span> sensing materials, based on <span class="hlt">strain</span>-induced stop band frequency shifting. Self-assembly of polystyrene microspheres, achieved by sedimentation over a flexible polyimide tape substrate whose surface hydrophilicity was optimized in order to achieve maximum wettability, led to an organized 3-D direct opal template. This was infiltrated with a silica sol-gel solution by dip-coating or by chemical vapour deposition and an inverse opal structure was ultimately obtained by chemical dissolution of the polymer template. The structural and optical properties of these PCs have been studied by scanning electron microscopy (FE-SEM) and UV/visible spectroscopy under variable degrees of <span class="hlt">strain</span>. FE-SEM showed the presence of ordered domains up to ∼30 μm2. A mechano-optical effect was evidenced by <span class="hlt">strain</span>-induced shifting of the photonic stop band peak wavelength of the direct, infiltrated and inverse opals up to 50 nm in transmission mode, due to changes in interplanar spacing upon bending the flexible PCs. Optical response <span class="hlt">strain</span> cycles were studied, suggesting the possible use of these structures in reversible photonic <span class="hlt">strain</span> sensors integrated in sensor/actuator devices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6722711','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6722711"><span>Fermentation studies using Saccharomyces diastaticus yeast <span class="hlt">strains</span></span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Erratt, J.A.; Stewart, G.G.</p> <p>1981-01-01</p> <p>The yeast species, Saccharomyces diastaticus, has the ability to ferment starch and dextrin, because of the extracellular enzyme, glucoamylase, which hydrolyzes the starch/dextrin to glucose. A number of nonallelic genes--DEX 1, DEX 2, and dextrinase B which is allelic to STA 3--have been isolated, which impart to the yeast the ability to ferment dextrin. Various diploid yeast <span class="hlt">strains</span> were constructed, each being either heterozygous or homozygous for the individual dextrinase genes. Using 12 (sup 0) plato hopped wort (30% corn adjunct) under agitated conditions, the fermentation rates of the various diploid yeast <span class="hlt">strains</span> were monitored. A gene-dosage effect was exhibited by yeast <span class="hlt">strains</span> containing DEX 1 or DEX 2, however, not with yeast <span class="hlt">strains</span> containing dextrinase B (STA 3). The fermentation and growth rates and extents were determined under static conditions at 14.4 C and 21 C. With all yeast <span class="hlt">strains</span> containing the dextrinase genes, both fermentation and growth were increased at the higher incubation temperature. Using 30-liter fermentors, beer was produced with the various yeast <span class="hlt">strains</span> containing the dextrinase genes and the physical and organoleptic characteristics of the products were determined. The concentration of glucose in the beer was found to increase during a 3-mo storage period at 21 C, indicating that the glucoamylase from Saccharomyces diastaticus is not inactivated by pasteurization. (Refs. 36).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/902633','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/902633"><span>Load cell having <span class="hlt">strain</span> gauges of arbitrary location</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Spletzer, Barry</p> <p>2007-03-13</p> <p>A load cell utilizes a plurality of <span class="hlt">strain</span> gauges mounted upon the load cell body such that there are six independent load-<span class="hlt">strain</span> relations. Load is determined by applying the inverse of a load-<span class="hlt">strain</span> sensitivity matrix to a measured <span class="hlt">strain</span> vector. The sensitivity matrix is determined by performing a multivariate regression technique on a set of known loads correlated to the resulting <span class="hlt">strains</span>. Temperature compensation is achieved by configuring the <span class="hlt">strain</span> gauges as co-located orthogonal pairs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18689636','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18689636"><span>Pathogenesis of XJ and Romero <span class="hlt">strains</span> of Junin virus in two <span class="hlt">strains</span> of guinea pigs.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yun, Nadezhda E; Linde, Nathaniel S; Dziuba, Natallia; Zacks, Michele A; Smith, Jeanon N; Smith, Jennifer K; Aronson, Judy F; Chumakova, Olga V; Lander, Heather M; Peters, Clarence J; Paessler, Slobodan</p> <p>2008-08-01</p> <p>Argentine hemorrhagic fever (AHF), a systemic infectious disease caused by infection with Junin virus, affects several organs, and patients can show hematologic, cardiovascular, renal, or neurologic symptoms. We compared the virulence of two Junin virus <span class="hlt">strains</span> in inbred and outbred guinea pigs with the aim of characterizing this animal model better for future vaccine/antiviral efficacy studies. Our data indicate that this passage of the XJ <span class="hlt">strain</span> is attenuated in guinea pigs. In contrast, the Romero <span class="hlt">strain</span> is highly virulent in <span class="hlt">Strain</span> 13 as well as in Hartley guinea pigs, resulting in systemic infection, thrombocytopenia, elevated aspartate aminotransferase levels, and ultimately, uniformly lethal disease. We detected viral antigen in formalin-fixed, paraffin-embedded tissues. Thus, both guinea pig <span class="hlt">strains</span> are useful animal models for lethal Junin virus (Romero <span class="hlt">strain</span>) infection and potentially can be used for preclinical trials in vaccine or antiviral drug development.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22021041','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22021041"><span>Molecular typing of Brucella melitensis endemic <span class="hlt">strains</span> and differentiation from the vaccine <span class="hlt">strain</span> Rev-1.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Noutsios, Georgios T; Papi, Rigini M; Ekateriniadou, Loukia V; Minas, Anastasios; Kyriakidis, Dimitrios A</p> <p>2012-03-01</p> <p>In the present study forty-four Greek endemic <span class="hlt">strains</span> of Br. melitensis and three reference <span class="hlt">strains</span> were genotyped by Multi locus Variable Number Tandem Repeat (ML-VNTR) analysis based on an eight-base pair tandem repeat sequence that was revealed in eight loci of Br. melitensis genome. The forty-four <span class="hlt">strains</span> were discriminated from the vaccine <span class="hlt">strain</span> Rev-1 by Restriction Fragment Length Polymorphism (RFLP) and Denaturant Gradient Gel Electrophoresis (DGGE). The ML-VNTR analysis revealed that endemic, reference and vaccine <span class="hlt">strains</span> are genetically closely related, while most of the loci tested (1, 2, 4, 5 and 7) are highly polymorphic with Hunter-Gaston Genetic Diversity Index (HGDI) values in the range of 0.939 to 0.775. Analysis of ML-VNTRs loci stability through in vitro passages proved that loci 1 and 5 are non stable. Therefore, vaccine <span class="hlt">strain</span> can be discriminated from endemic <span class="hlt">strains</span> by allele's clusters of loci 2, 4, 6 and 7. RFLP and DGGE were also employed to analyse omp2 gene and reveled different patterns among Rev-1 and endemic <span class="hlt">strains</span>. In RFLP, Rev-1 revealed three fragments (282, 238 and 44 bp), while endemic <span class="hlt">strains</span> two fragments (238 and 44 bp). As for DGGE, the electrophoretic mobility of Rev-1 is different from the endemic <span class="hlt">strains</span> due to heterologous binding of DNA chains of omp2a and omp2b gene. Overall, our data show clearly that it is feasible to genotype endemic <span class="hlt">strains</span> of Br. melitensis and differentiate them from vaccine <span class="hlt">strain</span> Rev-1 with ML-VNTR, RFLP and DGGE techniques. These tools can be used for conventional investigations in brucellosis outbreaks.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016RScI...87j2506M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016RScI...87j2506M"><span>On the use of <span class="hlt">strain</span> sensor technologies for <span class="hlt">strain</span> modal analysis: Case studies in aeronautical applications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Marques dos Santos, Fábio Luis; Peeters, Bart</p> <p>2016-10-01</p> <p>This paper discusses the use of optical fiber Bragg grating (FBG) and piezo <span class="hlt">strain</span> sensors for structural dynamic measurements. For certain industrial applications, there is an interest to use <span class="hlt">strain</span> sensors rather than in combination with accelerometers for experimental modal analysis. Classical electrical <span class="hlt">strain</span> gauges can be used hereto, but other types of <span class="hlt">strain</span> sensors are an interesting alternative with some very specific advantages. This work gives an overview of two types of dynamic <span class="hlt">strain</span> sensors, applied to two industrial applications (a helicopter main rotor blade and an F-16 aircraft), FBG sensors and dynamic piezo <span class="hlt">strain</span> sensors, discussing their use and benefits. Moreover, the concept of <span class="hlt">strain</span> modal analysis is introduced and it is shown how it can be beneficial to apply <span class="hlt">strain</span> 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 <span class="hlt">strain</span> sensors instead.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26360021','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26360021"><span>Genome-Wide Transcription Study of Cryptococcus neoformans H99 Clinical <span class="hlt">Strain</span> versus Environmental <span class="hlt">Strains</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Movahed, Elaheh; Munusamy, Komathy; Tan, Grace Min Yi; Looi, Chung Yeng; Tay, Sun Tee; Wong, Won Fen</p> <p>2015-01-01</p> <p>The infection of Cryptococcus neoformans is acquired through the inhalation of desiccated yeast cells and basidiospores originated from the environment, particularly from bird's droppings and decaying wood. Three environmental <span class="hlt">strains</span> of C. neoformans originated from bird droppings (H4, S48B and S68B) and C. neoformans reference clinical <span class="hlt">strain</span> (H99) were used for intranasal infection in C57BL/6 mice. We showed that the H99 <span class="hlt">strain</span> demonstrated higher virulence compared to H4, S48B and S68B <span class="hlt">strains</span>. To examine if gene expression contributed to the different degree of virulence among these <span class="hlt">strains</span>, a genome-wide microarray study was performed to inspect the transcriptomic profiles of all four <span class="hlt">strains</span>. Our results revealed that out of 7,419 genes (22,257 probes) examined, 65 genes were significantly up-or down-regulated in H99 versus H4, S48B and S68B <span class="hlt">strains</span>. The up-regulated genes in H99 <span class="hlt">strain</span> include Hydroxymethylglutaryl-CoA synthase (MVA1), Mitochondrial matrix factor 1 (MMF1), Bud-site-selection protein 8 (BUD8), High affinity glucose transporter 3 (SNF3) and Rho GTPase-activating protein 2 (RGA2). Pathway annotation using DAVID bioinformatics resource showed that metal ion binding and sugar transmembrane transporter activity pathways were highly expressed in the H99 <span class="hlt">strain</span>. We suggest that the genes and pathways identified may possibly play crucial roles in the fungal pathogenesis.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26063842','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26063842"><span>Bone <span class="hlt">strain</span> magnitude is correlated with bone <span class="hlt">strain</span> rate in tetrapods: implications for models of mechanotransduction.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Aiello, B R; Iriarte-Diaz, J; Blob, R W; Butcher, M T; Carrano, M T; Espinoza, N R; Main, R P; Ross, C F</p> <p>2015-07-07</p> <p>Hypotheses suggest that structural integrity of vertebrate bones is maintained by controlling bone <span class="hlt">strain</span> magnitude via adaptive modelling in response to mechanical stimuli. Increased tissue-level <span class="hlt">strain</span> magnitude and rate have both been identified as potent stimuli leading to increased bone formation. Mechanotransduction models hypothesize that osteocytes sense bone deformation by detecting fluid flow-induced drag in the bone's lacunar-canalicular porosity. This model suggests that the osteocyte's intracellular response depends on fluid-flow rate, a product of bone <span class="hlt">strain</span> rate and gradient, but does not provide a mechanism for detection of <span class="hlt">strain</span> magnitude. Such a mechanism is necessary for bone modelling to adapt to loads, because <span class="hlt">strain</span> magnitude is an important determinant of skeletal fracture. Using <span class="hlt">strain</span> gauge data from the limb bones of amphibians, reptiles, birds and mammals, we identified strong correlations between <span class="hlt">strain</span> rate and magnitude across clades employing diverse locomotor styles and degrees of rhythmicity. The breadth of our sample suggests that this pattern is likely to be a common feature of tetrapod bone loading. Moreover, finding that bone <span class="hlt">strain</span> magnitude is encoded in <span class="hlt">strain</span> rate at the tissue level is consistent with the hypothesis that it might be encoded in fluid-flow rate at the cellular level, facilitating bone adaptation via mechanotransduction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4567374','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4567374"><span>Genome-Wide Transcription Study of Cryptococcus neoformans H99 Clinical <span class="hlt">Strain</span> versus Environmental <span class="hlt">Strains</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Movahed, Elaheh; Munusamy, Komathy; Tan, Grace Min Yi; Looi, Chung Yeng; Tay, Sun Tee; Wong, Won Fen</p> <p>2015-01-01</p> <p>The infection of Cryptococcus neoformans is acquired through the inhalation of desiccated yeast cells and basidiospores originated from the environment, particularly from bird’s droppings and decaying wood. Three environmental <span class="hlt">strains</span> of C. neoformans originated from bird droppings (H4, S48B and S68B) and C. neoformans reference clinical <span class="hlt">strain</span> (H99) were used for intranasal infection in C57BL/6 mice. We showed that the H99 <span class="hlt">strain</span> demonstrated higher virulence compared to H4, S48B and S68B <span class="hlt">strains</span>. To examine if gene expression contributed to the different degree of virulence among these <span class="hlt">strains</span>, a genome-wide microarray study was performed to inspect the transcriptomic profiles of all four <span class="hlt">strains</span>. Our results revealed that out of 7,419 genes (22,257 probes) examined, 65 genes were significantly up-or down-regulated in H99 versus H4, S48B and S68B <span class="hlt">strains</span>. The up-regulated genes in H99 <span class="hlt">strain</span> include Hydroxymethylglutaryl-CoA synthase (MVA1), Mitochondrial matrix factor 1 (MMF1), Bud-site-selection protein 8 (BUD8), High affinity glucose transporter 3 (SNF3) and Rho GTPase-activating protein 2 (RGA2). Pathway annotation using DAVID bioinformatics resource showed that metal ion binding and sugar transmembrane transporter activity pathways were highly expressed in the H99 <span class="hlt">strain</span>. We suggest that the genes and pathways identified may possibly play crucial roles in the fungal pathogenesis. PMID:26360021</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850013288','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850013288"><span>Thin film <span class="hlt">strain</span> transducer. [suitable for in-flight measurement of scientific balloon <span class="hlt">strain</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rand, J. L. (Inventor)</p> <p>1985-01-01</p> <p>A <span class="hlt">strain</span> transducer system and process for making same is disclosed wherein a beryllium-copper ring having four <span class="hlt">strain</span> gages disposed thereon is electrically connected in Wheatstone bridge fashion to output instrumentation. Tabs are bonded to a balloon or like surface with <span class="hlt">strain</span> on the surface causing bending of the ring and providing an electrical signal through the gages proportional to the surface <span class="hlt">strain</span>. A figure is provided which illustrates a pattern of a one-half ring segment as placed on a sheet of beryllium-copper for chem-mill etch formation, prior to bending and welding of a pair of the segments to form a ring structure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/762874','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/762874"><span>Imploding Liner Material Strength Measurements at High-<span class="hlt">Strain</span> and High <span class="hlt">Strain</span> Rate</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Bartsch, R.R.; Lee, H.; Holtkamp, D.; Wright, B.; Stokes, J.; Morgan, D.; Anderson, W.; Broste, W.</p> <p>1998-10-18</p> <p>Imploding, cylindrical liners provide a unique, shockless means of simultaneously accessing high <span class="hlt">strain</span> and high-<span class="hlt">strain</span>-rate for measurement of strength of materials in plastic flow. The radial convergence in the liner geometry results in the liner thickening as the circumference becomes smaller. <span class="hlt">Strains</span> of up to {approximately}1.25 and <span class="hlt">strain</span> rates of up to {approximately}10{sup 6} sec{sup -1} can be readily achieved in a material sample placed inside of an aluminum driver liner, using the Pegasus II capacitor bank. This provides yield strength data at conditions where none presently exists. The heating from work done against the yield strength is measured with multichannel pyrometry from infrared radiation emitted by the material sample. The temperature data as a function of liner position are unfolded to give the yield strength along the <span class="hlt">strain</span>, <span class="hlt">strain</span>-rate trajectory. Proper design of the liner and sample configuration ensures that the current diffused into the sample adds negligible heating. An important issue, in this type of temperature measurement, is shielding of the pickup optics from other sources of radiation. At <span class="hlt">strains</span> greater than those achievable on Pegasus, e.g. the LANL Atlas facility, some materials may be heated all the way to melt by this process. Recent data on 6061-T6 Aluminum will be compared with an existing model for <span class="hlt">strain</span> and <span class="hlt">strain</span>-rate heating. The liner configuration and pyrometry diagnostic will also be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/960184','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/960184"><span>Stress-<span class="hlt">Strain</span> Relation and <span class="hlt">strain</span>-Induced Crystallization in Rubber</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Toki,S.</p> <p>2006-01-01</p> <p>Rubber is composed of flexible chains and network points. Theory of rubber elasticity succeeds to elucidate stress-<span class="hlt">strain</span> relation of rubber using the inverse Langevin equation of entropy modulus. However, actual rubber is much different from ideal networks composed of ideal rubber chains. Network points may not distribute homogeneously and the molecular weight between two network points may show wide distribution. Flexible chains show <span class="hlt">strain</span>-induced crystallization. Recent synchrotron X-ray and simultaneous stress-<span class="hlt">strain</span> measurements reveal that <span class="hlt">strain</span>-induced crystallization reduces the stress by increasing the length of molecules along the stretching direction. Also, <span class="hlt">strain</span>-induced crystals are created not at the middle of the network points, but at the close location to the network points. The hybrid structure of <span class="hlt">strain</span>-induced crystallites and network points may be stronger than network points alone. Therefore, <span class="hlt">strain</span> induced crystallization may increase the tensile strength of rubber by two mechanisms, they are, increase of elongation at break and reinforcement of network points. Natural rubber has biotic network points in nature. After vulcanization, the biotic network may contribute the superior toughness of NR, comparing to IR. Carbon filled NR also shows <span class="hlt">strain</span> induced crystallization. In order to acquire high tensile strength, molecules should have higher flexibility to perform <span class="hlt">strain</span> induced crystallization by selecting a kind of carbon blacks, an accelerator and a curing condition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4590470','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4590470"><span>Bone <span class="hlt">strain</span> magnitude is correlated with bone <span class="hlt">strain</span> rate in tetrapods: implications for models of mechanotransduction</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Aiello, B. R.; Iriarte-Diaz, J.; Blob, R. W.; Butcher, M. T.; Carrano, M. T.; Espinoza, N. R.; Main, R. P.; Ross, C. F.</p> <p>2015-01-01</p> <p>Hypotheses suggest that structural integrity of vertebrate bones is maintained by controlling bone <span class="hlt">strain</span> magnitude via adaptive modelling in response to mechanical stimuli. Increased tissue-level <span class="hlt">strain</span> magnitude and rate have both been identified as potent stimuli leading to increased bone formation. Mechanotransduction models hypothesize that osteocytes sense bone deformation by detecting fluid flow-induced drag in the bone's lacunar–canalicular porosity. This model suggests that the osteocyte's intracellular response depends on fluid-flow rate, a product of bone <span class="hlt">strain</span> rate and gradient, but does not provide a mechanism for detection of <span class="hlt">strain</span> magnitude. Such a mechanism is necessary for bone modelling to adapt to loads, because <span class="hlt">strain</span> magnitude is an important determinant of skeletal fracture. Using <span class="hlt">strain</span> gauge data from the limb bones of amphibians, reptiles, birds and mammals, we identified strong correlations between <span class="hlt">strain</span> rate and magnitude across clades employing diverse locomotor styles and degrees of rhythmicity. The breadth of our sample suggests that this pattern is likely to be a common feature of tetrapod bone loading. Moreover, finding that bone <span class="hlt">strain</span> magnitude is encoded in <span class="hlt">strain</span> rate at the tissue level is consistent with the hypothesis that it might be encoded in fluid-flow rate at the cellular level, facilitating bone adaptation via mechanotransduction. PMID:26063842</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APLM....4f4107S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APLM....4f4107S"><span>Elastocaloric cooling processes: The influence of material <span class="hlt">strain</span> and <span class="hlt">strain</span> rate on efficiency and temperature span</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schmidt, Marvin; Schütze, Andreas; Seelecke, Stefan</p> <p>2016-06-01</p> <p>This paper discusses the influence of material <span class="hlt">strain</span> and <span class="hlt">strain</span> 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 <span class="hlt">strains</span> and <span class="hlt">strain</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/305920','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/305920"><span>The influence of <span class="hlt">strain</span> rate and hydrogen on the plane-<span class="hlt">strain</span> ductility of Zircaloy cladding</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Link, T.M.; Motta, A.T.; Koss, D.A.</p> <p>1998-03-01</p> <p>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-<span class="hlt">strain</span> deformation in the hoop direction (transverse to the cladding axis) at room temperature and 300 C and high <span class="hlt">strain</span> rates. To conduct these studies, they developed a specimen configuration in which near plane-<span class="hlt">strain</span> deformation is achieved in the gage section, and a testing methodology that allows one to determine both the limit <span class="hlt">strain</span> at the onset of localized necking and the fracture <span class="hlt">strain</span>. The experiments indicate that there is little effect of <span class="hlt">strain</span> rate (10{sup {minus}3} to 10{sup 2} s{sup {minus}1}) on the ductility of unhydrided Zircaloy tubing deformed under near plane-<span class="hlt">strain</span> conditions at either room temperature or 300 C. Preliminary experiments on cladding containing 190 ppm hydrogen show only a small loss of fracture <span class="hlt">strain</span> but no clear effect on limit <span class="hlt">strain</span>. The experiments also indicate that there is a significant loss of Zircaloy ductility when surface flaws are present in the form of thickness imperfections.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://dx.doi.org/10.1785/0220160155','USGSPUBS'); return false;" href="https://dx.doi.org/10.1785/0220160155"><span>Dynamic <span class="hlt">strains</span> for earthquake source characterization</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Barbour, Andrew; Crowell, Brendan W</p> <p>2017-01-01</p> <p>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 <span class="hlt">strains</span> 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 <span class="hlt">strain</span> 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 <span class="hlt">strain</span> 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 <span class="hlt">strains</span> than earthquakes around the Sierra Nevada microplate and in the Salton trough. Finally, we test our dynamic <span class="hlt">strain</span> prediction equations on the 2011 M 9 Tohoku‐Oki earthquake, specifically continuous <span class="hlt">strain</span> 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 <span class="hlt">strain</span> model are in agreement when Global Positioning System subnetworks are unaffected by spatial aliasing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/20215607','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/20215607"><span>Volume <span class="hlt">strain</span> within the Geysers geothermal field</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Mossop, Antony; Segall, Paul</p> <p>1999-12-10</p> <p>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 <span class="hlt">strain</span> 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 <span class="hlt">strain</span> within the reservoir. For the period 1980-1994, peak volume <span class="hlt">strains</span> 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 <span class="hlt">strain</span>. If reservoir pressure changes are inducing volume <span class="hlt">strain</span>, 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 <span class="hlt">strain</span> is observed. However, earthquake distribution does not appear to have a simple relationship with volume <span class="hlt">strain</span> rate. (c) 1999 American Geophysical Union.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17093023','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17093023"><span><span class="hlt">Strain</span>-specific single-nucleotide polymorphism assays for the Bacillus anthracis Ames <span class="hlt">strain</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Van Ert, Matthew N; Easterday, W Ryan; Simonson, Tatum S; U'Ren, Jana M; Pearson, Talima; Kenefic, Leo J; Busch, Joseph D; Huynh, Lynn Y; Dukerich, Megan; Trim, Carla B; Beaudry, Jodi; Welty-Bernard, Amy; Read, Timothy; Fraser, Claire M; Ravel, Jacques; Keim, Paul</p> <p>2007-01-01</p> <p>Highly precise diagnostics and forensic assays can be developed through a combination of evolutionary analysis and the exhaustive examination of genomic sequences. In Bacillus anthracis, whole-genome sequencing efforts revealed ca. 3,500 single-nucleotide polymorphisms (SNPs) among eight different <span class="hlt">strains</span> and evolutionary analysis provides the identification of canonical SNPs. We have previously shown that SNPs are highly evolutionarily stable, and the clonal nature of B. anthracis makes them ideal signatures for subtyping this pathogen. Here we identified SNPs that define the lineage of B. anthracis that contains the Ames <span class="hlt">strain</span>, the <span class="hlt">strain</span> used in the 2001 bioterrorist attacks in the United States. Sequencing and real-time PCR were used to validate these SNPs across B. anthracis <span class="hlt">strains</span>, including (i) 88 globally and genetically diverse isolates; (ii) isolates that were shown to be genetic relatives of the Ames <span class="hlt">strain</span> by multiple-locus variable number tandem repeat analysis (MLVA); and (iii) several different lab stocks of the Ames <span class="hlt">strain</span>, including a clinical isolate from the 2001 letter attack. Six SNPs were found to be highly specific for the Ames <span class="hlt">strain</span>; four on the chromosome, one on the pX01 plasmid, and one on the pX02 plasmid. All six SNPs differentiated the B. anthracis Ames <span class="hlt">strain</span> from the 88 unique B. anthracis <span class="hlt">strains</span>, while five of the six separated Ames from its close genetic relatives. The use of these SNPs coupled with real-time PCR allows specific and sensitive (<100 fg of template DNA) identification of the Ames <span class="hlt">strain</span>. This evolutionary and genomics-based approach provides an effective means for the discovery of <span class="hlt">strain</span>-specific SNPs in B. anthracis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19810062035&hterms=behavior+analysis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dbehavior%2Banalysis','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19810062035&hterms=behavior+analysis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dbehavior%2Banalysis"><span>Analysis of the tensile stress-<span class="hlt">strain</span> behavior of elastomers at constant <span class="hlt">strain</span> rates. I - Criteria for separability of the time and <span class="hlt">strain</span> effects</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hong, S. D.; Fedors, R. F.; Schwarzl, F.; Moacanin, J.; Landel, R. F.</p> <p>1981-01-01</p> <p>A theoretical analysis of the tensile stress-<span class="hlt">strain</span> relation of elastomers at constant <span class="hlt">strain</span> 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-<span class="hlt">strain</span> separability is valid if the <span class="hlt">strain</span> function is linearly proportional to the Cauchy <span class="hlt">strain</span>, and that when time-<span class="hlt">strain</span> separability holds, two <span class="hlt">strain</span>-dependent quantities can be obtained experimentally. In the case where time and <span class="hlt">strain</span> effect are not separable, superposition can be achieved only by using temperature and <span class="hlt">strain</span>-dependent shift factors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3942497','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3942497"><span>The Effect of Ivermectin in Seven <span class="hlt">Strains</span> of Aedes aegypti (Diptera: Culicidae) Including a Genetically Diverse Laboratory <span class="hlt">Strain</span> and Three Permethrin Resistant <span class="hlt">Strains</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Deus, K. M.; Saavedra-rodriguez, K.; Butters, M. P.; Black, W. C.; Foy, B. D.</p> <p>2014-01-01</p> <p>Seven different <span class="hlt">strains</span> of Aedes aegypti (L.), including a genetically diverse laboratory <span class="hlt">strain</span>, three laboratory-selected permethrin-resistant <span class="hlt">strains</span>, a standard reference <span class="hlt">strain</span>, and two recently colonized <span class="hlt">strains</span> 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 <span class="hlt">strains</span>. The LC50 of ivermectin for adults and the concentration that prevented 50% of eggs from hatching was calculated for all <span class="hlt">strains</span>. Considerable variation in adult survival after an ivermectin-bloodmeal occurred among <span class="hlt">strains</span>, and all three permethrin-resistant <span class="hlt">strains</span> were significantly less susceptible to ivermectin than the standard reference <span class="hlt">strain</span>. The hatch rate after an ivermectin bloodmeal was less variable among <span class="hlt">strains</span>, and only one of the permethrin-resistant <span class="hlt">strains</span> differed significantly from the standard reference <span class="hlt">strain</span>. 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 <span class="hlt">strains</span> suggests that permethrin and ivermectin cross-resistance may occur. PMID:22493855</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015PhDT.......536S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015PhDT.......536S"><span>Anisotropic nature of radially <span class="hlt">strained</span> metal tubes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Strickland, Julie N.</p> <p></p> <p>Metal pipes are sometimes swaged by a metal cone to enlarge them, which increases the <span class="hlt">strain</span> in the material. The amount of <span class="hlt">strain</span> is important because it affects the burst and collapse strength. Burst strength is the amount of internal pressure that a pipe can withstand before failure, while collapse strength is the amount of external pressure that a pipe can withstand before failure. If the burst or collapse strengths are exceeded, the pipe may fracture, causing critical failure. Such an event could cost the owners and their customers millions of dollars in clean up, repair, and lost time, in addition to the potential environmental damage. Therefore, a reliable way of estimating the burst and collapse strength of <span class="hlt">strained</span> pipe is desired and valuable. The sponsor currently rates <span class="hlt">strained</span> pipes using the properties of raw steel, because those properties are easily measured (for example, yield strength). In the past, the engineers assumed that the metal would be work-hardened when swaged, so that yield strength would increase. However, swaging introduces anisotropic <span class="hlt">strain</span>, which may decrease the yield strength. This study measured the yield strength of <span class="hlt">strained</span> material in the transverse and axial direction and compared them to raw material, to determine the amount of anisotropy. This information will be used to more accurately determine burst and collapse ratings for <span class="hlt">strained</span> pipes. More accurate ratings mean safer products, which will minimize risk for the sponsor's customers. Since the <span class="hlt">strained</span> metal has a higher yield strength than the raw material, using the raw yield strength to calculate burst and collapse ratings is a conservative method. The metal has even higher yield strength after <span class="hlt">strain</span> aging, which indicates that the stresses are relieved. Even with the 12% anisotropy in the <span class="hlt">strained</span> and 9% anisotropy in the <span class="hlt">strain</span> aged specimens, the raw yield strengths are lower and therefore more conservative. I recommend that the sponsor continue using the raw</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11874722','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11874722"><span>Growth <span class="hlt">strain</span> in coconut palm trees.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Huang, Yan S; Chen, Shin S; Lin, Tsan P; Chen, Yuh S</p> <p>2002-03-01</p> <p>Until recently, growth stress studies have been made only on coniferous and dicotyledonous trees. Growth stress of trees is thought to be initiated in newly formed secondary xylem cells. This stress can accumulate for years and is distributed inside the trunk. Major characteristics of the trunk of monocotyledonous trees include numerous vascular bundles scattered inside the ground tissue and the lack of secondary growth for enlarging the diameter of the trunk. We used the <span class="hlt">strain</span> gauge method to measure the released growth <span class="hlt">strain</span> of the monocotyledonous woody palm, coconut (Cocos nucifera L.), and to investigate the surface growth <span class="hlt">strain</span> of the trunk and central cylinder at different trunk heights. The internal <span class="hlt">strains</span> of both vertical and leaning trunks were measured and compared with those of coniferous and dicotyledonous trees. We found that tensile stress existed longitudinally on the surface of vertically growing trunks, whereas compression stress was found at the bending position of leaning trunks. Compression stress was found in the outer part of the central cylinder, whereas tensile stress is generally found in the outer part of the trunk in coniferous and dicotyledonous trees. The distribution of <span class="hlt">strain</span> in the palm trunk is similar to that of compression wood of the leaning trunk of a conifer. Specific gravity was greater in the outer part of the trunk than in the inner part of the trunk. This difference may be related to the distribution of growth stress.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/1015378','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/1015378"><span>Brittle superconducting magnets: an equivilent <span class="hlt">strain</span> model</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Barzi, E.; Danuso, M.</p> <p>2010-08-01</p> <p>To exceed fields of 10 T in accelerator magnets, brittle superconductors like A15 Nb{sub 3}Sn and Nb{sub 3}Al or ceramic High Temperature Superconductors have to be used. For such brittle superconductors it is not their maximum tensile yield stress that limits their structural resistance as much as <span class="hlt">strain</span> values that provoke deformations in their delicate lattice, which in turn affect their superconducting properties. Work on the sensitivity of Nb{sub 3}Sn cables to <span class="hlt">strain</span> has been conducted in a number of stress states, including uniaxial and multi-axial, producing usually different results. This has made the need of a constituent design criterion imperative for magnet builders. In conventional structural problems an equivalent stress model is typically used to verify mechanical soundness. In the superconducting community a simple scalar equivalent <span class="hlt">strain</span> to be used in place of an equivalent stress would be an extremely useful tool. As is well known in fundamental mechanics, there is not one single way to reduce a multiaxial <span class="hlt">strain</span> state as represented by a 2nd order tensor to a scalar. The conceptual experiment proposed here will help determine the best scalar representation to use in the identification of an equivalent <span class="hlt">strain</span> model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19860008318','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19860008318"><span>Closure of fatigue cracks at high <span class="hlt">strains</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Iyyer, N. S.; Dowling, N. E.</p> <p>1985-01-01</p> <p>Experiments were conducted on smooth specimens to study the closure behavior of short cracks at high cyclic <span class="hlt">strains</span> under completely reversed cycling. Testing procedures and methodology, and closure measurement techniques, are described in detail. The <span class="hlt">strain</span> levels chosen for the study cover from predominantly elastic to grossly plastic <span class="hlt">strains</span>. Crack closure measurements are made at different crack lengths. The study reveals that, at high <span class="hlt">strains</span>, cracks close only as the lowest stress level in the cycle is approached. The crack opening is observed to occur in the compressive part of the loading cycle. The applied stress needed to open a short crack under high <span class="hlt">strain</span> is found to be less than for cracks under small scale yielding. For increased plastic deformations, the value of sigma sub op/sigma sub max is observed to decrease and approaches the value of R. Comparison of the experimental results with existing analysis is made and indicates the limitations of the small scale yielding approach where gross plastic deformation behavior occurs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22398929','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22398929"><span>Secretome analysis of Clostridium difficile <span class="hlt">strains</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Boetzkes, Alexander; Felkel, Katharina Wiebke; Zeiser, Johannes; Jochim, Nelli; Just, Ingo; Pich, Andreas</p> <p>2012-08-01</p> <p>Clostridium difficile causes infections ranging from mild C. difficile-associated diarrhea to severe pseudomembranous colitis. Since 2003 new hypervirulent C. difficile <span class="hlt">strains</span> (PCR ribotype 027) emerged characterized by a dramatically increased mortality. The secretomes of the three C. difficile <span class="hlt">strains</span> CDR20291, CD196, and CD630 were analyzed and compared. Proteins were separated and analyzed by means of SDS--PAGE and LC-MS. MS data were analyzed using Mascot and proteins were checked for export signals with SecretomeP and SignalP. LC-MS analysis revealed 158 different proteins in the supernatant of C. difficile. Most of the identified proteins originate from the cytoplasm. Thirty-two proteins in CDR20291, 36 in CD196 and 26 in CD630 were identified to be secreted by C. difficile <span class="hlt">strains</span>. Those were mainly S-layer proteins, substrate-binding proteins of ABC-transporters, cell wall hydrolases, pilin and unknown hypothetical proteins. Toxin A and toxin B were identified after growth in brain heart infusion medium using immunological techniques. The ADP-ribosyltransferase-binding component protein, which is a part of the binary toxin CDT, was only identified in the hypervirulent ribotype 027 <span class="hlt">strains</span>. Further proteins that are secreted specifically by hypervirulent <span class="hlt">strains</span> were identified.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3575016','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3575016"><span>Fast flexible electronics with <span class="hlt">strained</span> silicon nanomembranes</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Zhou, Han; Seo, Jung-Hun; Paskiewicz, Deborah M.; Zhu, Ye; Celler, George K.; Voyles, Paul M.; Zhou, Weidong; Lagally, Max G.; Ma, Zhenqiang</p> <p>2013-01-01</p> <p>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 <span class="hlt">strain</span> 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 <span class="hlt">strained</span>- NM-compatible doping techniques with self-sustained-<span class="hlt">strain</span> sharing by applying a <span class="hlt">strain</span>-sharing scheme between Si and SiGe multiple epitaxial layers, to create <span class="hlt">strained</span> print-transferrable SiNMs. We demonstrate a new speed record of Si-based flexible electronics without using aggressively scaled critical device dimensions. PMID:23416347</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25111022','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25111022"><span>Genomics of Clostridium botulinum group III <span class="hlt">strains</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sakaguchi, Yoshihiko; Suzuki, Tomonori; Yamamoto, Yumiko; Nishikawa, Atsushi; Oguma, Keiji</p> <p>2015-05-01</p> <p>In Clostridium botulinum, the characteristics of type C and D <span class="hlt">strains</span> 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 <span class="hlt">strains</span> to non-toxigenic <span class="hlt">strains</span> by the specific bacteriophages (phages), whereas, the C2 toxin gene is carried by large or small plasmids. Classification of type C and D <span class="hlt">strains</span> 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 <span class="hlt">strains</span> 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.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27585446','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27585446"><span>Computer modelling of bone's adaptation: the role of normal <span class="hlt">strain</span>, shear <span class="hlt">strain</span> and fluid flow.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tiwari, Abhishek Kumar; Prasad, Jitendra</p> <p>2017-04-01</p> <p>Bone loss is a serious health problem. In vivo studies have found that mechanical stimulation may inhibit bone loss as elevated <span class="hlt">strain</span> in bone induces osteogenesis, i.e. new bone formation. However, the exact relationship between mechanical environment and osteogenesis is less clear. Normal <span class="hlt">strain</span> 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 <span class="hlt">strain</span>, 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 <span class="hlt">strain</span> or canalicular fluid flow. As it is evident from the literature, shear <span class="hlt">strain</span> 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 <span class="hlt">strain</span> 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 <span class="hlt">strain</span>, and shear <span class="hlt">strain</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015CPL...625...69R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015CPL...625...69R"><span><span class="hlt">Strain</span> in <span class="hlt">strain</span>-free benzenoid hydrocarbons: The case of phenanthrene</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Radenković, Slavko; Gutman, Ivan; Đorđević, Slađana</p> <p>2015-04-01</p> <p>Benzenoid molecules possessing bays are traditionally considered as '<span class="hlt">strain</span>-free'. Yet, repulsion between the two bay H-atoms affects the length of the near-lying carbon-carbon bonds. A method is developed to estimate the energy of this <span class="hlt">strain</span>. In the case of phenanthrene its value was found to be about 7 kJ/mol.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4306125','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4306125"><span>MRI-based <span class="hlt">strain</span> and <span class="hlt">strain</span> rate analysis of left ventricle: a modified hierarchical transformation model</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2015-01-01</p> <p>Background Different from other indicators of cardiac function, such as ejection fraction and transmitral early diastolic velocity, myocardial <span class="hlt">strain</span> is promising to capture subtle alterations that result from early diseases of the myocardium. In order to extract the left ventricle (LV) myocardial <span class="hlt">strain</span> and <span class="hlt">strain</span> rate from cardiac cine-MRI, a modified hierarchical transformation model was proposed. Methods A hierarchical transformation model including the global and local LV deformations was employed to analyze the <span class="hlt">strain</span> and <span class="hlt">strain</span> rate of the left ventricle by cine-MRI image registration. The endocardial and epicardial contour information was introduced to enhance the registration accuracy by combining the original hierarchical algorithm with an Iterative Closest Points using Invariant Features algorithm. The hierarchical model was validated by a normal volunteer first and then applied to two clinical cases (i.e., the normal volunteer and a diabetic patient) to evaluate their respective function. Results Based on the two clinical cases, by comparing the displacement fields of two selected landmarks in the normal volunteer, the proposed method showed a better performance than the original or unmodified model. Meanwhile, the comparison of the radial <span class="hlt">strain</span> between the volunteer and patient demonstrated their apparent functional difference. Conclusions The present method could be used to estimate the LV myocardial <span class="hlt">strain</span> and <span class="hlt">strain</span> rate during a cardiac cycle and thus to quantify the analysis of the LV motion function. PMID:25602778</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830024945','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830024945"><span>Effect of <span class="hlt">strain</span> isolator pad modulus on inplane <span class="hlt">strain</span> in Shuttle Orbiter thermal protection system tiles</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sawyer, J. W.</p> <p>1983-01-01</p> <p>The thermal protection system used on the Space Shuttle orbiter to determine <span class="hlt">strains</span> in the reusable surface insulation tiles under simulated flight loads was investigated. The effects of changes in the <span class="hlt">strain</span> isolator pad (SIP) moduli on the <span class="hlt">strains</span> in the tile were evaluated. To analyze the SIP/tile system, it was necessary to conduct tests to determine inplane tension and compression modulus and inplane failure <span class="hlt">strain</span> for the densified layer of the tiles. It is shown that densification of the LI-900 tile material increases the modulus by a factor of 6 to 10 and reduces the failure <span class="hlt">strain</span> by about 50%. It is indicated that the inplane <span class="hlt">strain</span> levels in the Shuttle tiles in the highly loaded regions are approximately 2 orders of magnitude lower than the failure <span class="hlt">strain</span> of the material. It is concluded that most of the LI-900 tiles on the Shuttle could be mounted on a SIP with tensile and shear stiffnesses 10 times those of the present SIP without inplane <span class="hlt">strain</span> failure in the tile.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22840216','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22840216"><span>Hepatitis E virus <span class="hlt">strains</span> in rabbits and evidence of a closely related <span class="hlt">strain</span> in humans, France.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Izopet, Jacques; Dubois, Martine; Bertagnoli, Stéphane; Lhomme, Sébastien; Marchandeau, Stéphane; Boucher, Samuel; Kamar, Nassim; Abravanel, Florence; Guérin, Jean-Luc</p> <p>2012-08-01</p> <p>Hepatitis E virus (HEV) <span class="hlt">strains</span> from rabbits indicate that these mammals may be a reservoir for HEVs that cause infection in humans. To determine HEV prevalence in rabbits and the <span class="hlt">strains</span>' genetic characteristics, we tested bile, liver, and additional samples from farmed and wild rabbits in France. We detected HEV RNA in 7% (14/200) of bile samples from farmed rabbits (in 2009) and in 23% (47/205) of liver samples from wild rabbits (in 2007-2010). Full-length genomic sequences indicated that all rabbit <span class="hlt">strains</span> belonged to the same clade (nucleotide sequences 72.2%-78.2% identical to HEV genotypes 1-4). Comparison with HEV sequences of human <span class="hlt">strains</span> and reference sequences identified a human <span class="hlt">strain</span> closely related to rabbit <span class="hlt">strain</span> HEV. We found a 93-nt insertion in the X domain of open reading frame 1 of the human <span class="hlt">strain</span> and all rabbit HEV <span class="hlt">strains</span>. These findings indicate that the host range of HEV in Europe is expanding and that zoonotic transmission of HEV from rabbits is possible.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850007898','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850007898"><span>Measurement of high temperature <span class="hlt">strain</span> by the laser-speckle <span class="hlt">strain</span> gauge</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Yamaguchi, I.</p> <p>1984-01-01</p> <p>By using the laser-speckle <span class="hlt">strain</span> gauge, the <span class="hlt">strain</span> of metal at the temperature lower than 250 C is measured. The principle of the gauge is to measure the expansion or contraction of the fine structures of surface by detecting the resultant speckle displacement in an optoelectronic way, whereby the effect of rigid-body motion is automatically cancelled out with the aid of a differential detection system. A transportable apparatus was built and a comparison experiment performed with a resistance <span class="hlt">strain</span> gauge at room temperature. It has a <span class="hlt">strain</span> sensitivity of .00002, a gauge length smaller than 1 mm, and no upper limit in a range of <span class="hlt">strain</span> measurement. In the measurement of high-temperature <span class="hlt">strain</span> it is free from the need for a dummy gauge and insensitive to an electric drift effect. As examples of <span class="hlt">strain</span> measurement at high-temperature, thermal expansion and contraction of a top of a soldering iron are measured. The interval of the measurement can be made at shortest 1.6 sec. and the change in the <span class="hlt">strain</span> is clearly followed until the ultimate stationary temperature is reached.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16178463','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16178463"><span>[Deoxyribonuclease activity detection in Clostridium chauvoei <span class="hlt">strains</span>].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Carloni, G H; Bentancor, L D; De Torres, R A</p> <p>2005-01-01</p> <p>Beta toxin of C. chauvoei has desoxiribonuclease (DNase) activity which is regarded as one of its virulence factors. The production of DNase was detected in <span class="hlt">strains</span> isolated from bovines, using as controls C. chauvoei ATCC 10092, and C. perfringens Type A and C. septicum, both laboratory isolates. The enzyme activity was made evident on a DNA substrate observing the macroscopic degradation. A simple methodology was developed using a commercial medium for DNase test, with the incorporation of sterile horse serum. Each <span class="hlt">strain</span> was streaked on the surface of the medium, incubated in anaerobic atmosphere at 37 degrees C for 48 hours. The plates were revealed with HCI 1 N. The appearance of a clear and transparent zone around and under the microbial growing was considered a positive reaction. Enzyme activity was detected in 10 of 12 <span class="hlt">strains</span> and also in the controls. The serum addition to the commercial basal medium allows the optimum development of the microorganism showing the enzymatic digestion zone.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21666210','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21666210"><span>Genetic characterization of measles vaccine <span class="hlt">strains</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bankamp, Bettina; Takeda, Makoto; Zhang, Yan; Xu, Wenbo; Rota, Paul A</p> <p>2011-07-01</p> <p>The complete genomic sequences of 9 measles vaccine <span class="hlt">strains</span> were compared with the sequence of the Edmonston wild-type virus. AIK-C, Moraten, Rubeovax, Schwarz, and Zagreb are vaccine <span class="hlt">strains</span> 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 <span class="hlt">strains</span>. 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..MAR.F4002B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..MAR.F4002B"><span>Diffraction Correlation to Reconstruct Highly <span class="hlt">Strained</span> Particles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brown, Douglas; Harder, Ross; Clark, Jesse; Kim, J. W.; Kiefer, Boris; Fullerton, Eric; Shpyrko, Oleg; Fohtung, Edwin</p> <p>2015-03-01</p> <p>Through the use of coherent x-ray diffraction a three-dimensional diffraction pattern of a highly <span class="hlt">strained</span> 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 <span class="hlt">strained</span> 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 <span class="hlt">strained</span> nano-crystals.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1981RScI...52.1417R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1981RScI...52.1417R"><span>Simple and sensitive <span class="hlt">strain</span> gauge displacement transducer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ramana, Y. V.; Sarma, L. P.</p> <p>1981-09-01</p> <p>We describe a simple and sensitive <span class="hlt">strain</span> gauge displacement transducer. It is based on the linear movement of a shaft (with two cantilevers and four <span class="hlt">strain</span> gauges) in a tapered chamber, resulting in a change in resistance proportional to the cantilever deformation. The transducer with its Wheatstone full bridge configuration is calibrated against a mechanical dial indicator of 0.002 mm accuracy for both ac and dc voltage excitations. Its output is linear for measurements of full range displacement up to 25 mm. It has a sensitivity of ±0.0082 mm for ac excitation with a <span class="hlt">strain</span> indicator whose resolution is ±1 μɛ. It has a dc full range sensitivity of 1.5 mV/V for excitation levels up to 5 V. It can have varied field and laboratory applications wherever displacements are precisely read, recorded, or monitored.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4286197','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4286197"><span>Genome sequence of Coxiella burnetii <span class="hlt">strain</span> Namibia</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2014-01-01</p> <p>We present the whole genome sequence and annotation of the Coxiella burnetii <span class="hlt">strain</span> Namibia. This <span class="hlt">strain</span> was isolated from an aborting goat in 1991 in Windhoek, Namibia. The plasmid type QpRS was confirmed in our work. Further genomic typing placed the <span class="hlt">strain</span> into a unique genomic group. The genome sequence is 2,101,438 bp long and contains 1,979 protein-coding and 51 RNA genes, including one rRNA operon. To overcome the poor yield from cell culture systems, an additional DNA enrichment with whole genome amplification (WGA) methods was applied. We describe a bioinformatics pipeline for improved genome assembly including several filters with a special focus on WGA characteristics. PMID:25593636</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19777804','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19777804"><span>[Novel methods and strategies for <span class="hlt">strain</span> improvement].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhao, Wenting; Zou, Yi; Hu, Changhua</p> <p>2009-06-01</p> <p>Improvement of the productivity of industrial <span class="hlt">strains</span> is an important field in micro-biology, because wild-type <span class="hlt">strains</span> isolated from nature usually produce only a low level of antibiotics. Although random screening and simple rational screening are still effective without using genomic information, they are always time- and labor-consuming. With the broad application of recombinant DNA technology, protoplast fusion and X-omics, novel methods and strategies such as metabolic engineering, genome shuffling, system biology and system biotechnology, ribosome engineering, epigenetic modification are being exploited for the industry microbiology. In this review, we will focus on the progress of these novel methods and strategies for <span class="hlt">strain</span> improvement in recent years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SMaS...25j5008X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SMaS...25j5008X"><span>High sensitivity knitted fabric <span class="hlt">strain</span> sensors</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xie, Juan; Long, Hairu; Miao, Menghe</p> <p>2016-10-01</p> <p>Wearable sensors are increasingly used in smart garments for detecting and transferring vital signals and body posture, movement and respiration. Existing fabric <span class="hlt">strain</span> sensors made from metallized yarns have low sensitivity, poor comfort and low durability to washing. Here we report a knitted fabric <span class="hlt">strain</span> 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 <span class="hlt">strain</span> applied to hooked yarn loops.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150000844','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150000844"><span>Wing Shape Sensing from Measured <span class="hlt">Strain</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pak, Chan-Gi</p> <p>2015-01-01</p> <p>A new two step theory is investigated for predicting the deflection and slope of an entire structure using <span class="hlt">strain</span> measurements at discrete locations. In the first step, a measured <span class="hlt">strain</span> is fitted using a piecewise least squares curve fitting method together with the cubic spline technique. These fitted <span class="hlt">strains</span> are integrated twice to obtain deflection data along the fibers. In the second step, computed deflection along the fibers are combined with a finite element model of the structure in order to extrapolate the deflection and slope of the entire structure through the use of System Equivalent Reduction and Expansion Process. The theory is first validated on a computational model, a cantilevered rectangular wing. It is then applied to test data from a cantilevered swept wing model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26424643','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26424643"><span>Epstein-Barr Virus <span class="hlt">Strain</span> Variation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Farrell, Paul J</p> <p>2015-01-01</p> <p>What is wild-type Epstein-Barr virus and are there genetic differences in EBV <span class="hlt">strains</span> that contribute to some of the EBV-associated diseases? Recent progress in DNA sequencing has resulted in many new Epstein-Barr virus (EBV) genome sequences becoming available. EBV isolates worldwide can be grouped into type 1 and type 2, a classification based on the EBNA2 gene sequence. Type 1 transforms human B cells into lymphoblastoid cell lines much more efficiently than type 2 EBV and molecular mechanisms that may account for this difference in cell transformation are now becoming understood. Study of geographic variation of EBV <span class="hlt">strains</span> independent of the type 1/type 2 classification and systematic investigation of the relationship between viral <span class="hlt">strains</span>, infection and disease are now becoming possible. So we should consider more directly whether viral sequence variation might play a role in the incidence of some EBV-associated diseases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11712610','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11712610"><span>Conservative treatment for repetitive <span class="hlt">strain</span> injury.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Konijnenberg, H S; de Wilde, N S; Gerritsen, A A; van Tulder, M W; de Vet, H C</p> <p>2001-10-01</p> <p>Various conservative treatment options for repetitive <span class="hlt">strain</span> injury are widely used, despite questionable evidence of their effectiveness. This systematic review evaluates the effectiveness of these treatment options for relieving symptoms of repetitive <span class="hlt">strain</span> injury and improving activities of daily living. Searches in Medline and Embase, with additional reference checking resulted in 15 eligible trials for this review. Methodological quality was assessed, and data-extraction was performed. With the use of a "best-evidence synthesis", no strong evidence was found for the effectiveness of any of the treatment options. There is limited evidence that multidisciplinary rehabilitation, ergonomic intervention measures, exercises, and spinal manipulation combined with soft tissue therapy are effective in providing symptom relief or improving activities of daily living. There is conflicting evidence for the effectiveness of behavioral therapy. In conclusion, little is known about the effectiveness of conservative treatment options for repetitive <span class="hlt">strain</span> injury. To establish strong evidence, more high-quality trials are needed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/956356','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/956356"><span>The breaking <span class="hlt">strain</span> of neutron star crust</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kadau, Kai; Horowitz, C J</p> <p>2009-01-01</p> <p>Mountains on rapidly rotating neutron stars efficiently radiate gravitational waves. The maximum possible size of these mountains depends on the breaking <span class="hlt">strain</span> of neutron star crust. With multimillion ion molecular dynamics simulations of Coulomb solids representing the crust, we show that the breaking <span class="hlt">strain</span> of pure single crystals is very large and that impurities, defects, and grain boundaries only modestly reduce the breaking <span class="hlt">strain</span> to around 0.1. Due to the collective behavior of the ions during failure found in our simulations, the neutron star crust is likely very strong and can support mountains large enough so that their gTavitational wave radiation could limit the spin periods of some stars and might be detectable in large scale interferometers. Furthermore, our microscopic modeling of neutron star crust material can help analyze mechanisms relevant in Magnetar Giant and Micro Flares.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3586687','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3586687"><span>Convergent Replication of Mouse Synthetic Prion <span class="hlt">Strains</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ghaemmaghami, Sina; Colby, David W.; Nguyen, Hoang-Oanh B.; Hayashi, Shigenari; Oehler, Abby; DeArmond, Stephen J.; Prusiner, Stanley B.</p> <p>2014-01-01</p> <p>Prion diseases are neurodegenerative disorders characterized by the aberrant folding of endogenous proteins into self-propagating pathogenic conformers. Prion disease can be initiated in animal models by inoculation with amyloid fibrils formed from bacterially derived recombinant prion protein. The synthetic prions that accumulated in infected organisms are structurally distinct from the amyloid preparations used to initiate their formation and change conformationally on repeated passage. To investigate the nature of synthetic prion transformation, we infected mice with a conformationally diverse set of amyloids and serially passaged the resulting prion <span class="hlt">strains</span>. At each passage, we monitored changes in the biochemical and biological properties of the adapting <span class="hlt">strain</span>. The physicochemical properties of each synthetic prion <span class="hlt">strain</span> gradually changed on serial propagation until attaining a common adapted state with shared physicochemical characteristics. These results indicate that synthetic prions can assume multiple intermediate conformations before converging into one conformation optimized for in vivo propagation. PMID:23438476</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/6217136','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/6217136"><span>Glycerol production of various <span class="hlt">strains</span> of saccharomyces</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Radler, F.; Schuetz, H.</p> <p>1982-01-01</p> <p>The quantity of glycerol as principal by-product of the alcoholic fermentation depends to a large extent on the yeast <span class="hlt">strain</span>. Different <span class="hlt">strains</span> of Saccharomyces cerevisiae were found to form amounts of glycerol varying between 4.2 to 10.4 g/L. The formation of glycerol is regarded as a result of the competition between alcohol dehydrogenase and glycerol-3-phosphate dehydrogenase that compete for the reduced coenzyme NADH/sub 2/. High and low glycerol forming yeast <span class="hlt">strains</span> showed large differences in the activity of glycerol-3-phosphate dehydrogenase and only small variation in the activity of alcohol dehydrogenase. The total amount of glycerol formed was also influenced by amino acids. In thiamine deficient media a decrease in glycerol formation was observed. Experiments indicate a correlation between the formation of acetaldehyde and glycerol and the production of cell mass that may be of practical interest. (Refs. 12).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19950022297','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19950022297"><span>Test load verification through <span class="hlt">strain</span> data analysis</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Verderaime, V.; Harrington, F.</p> <p>1995-01-01</p> <p>A traditional binding acceptance criterion on polycrystalline structures is the experimental verification of the ultimate factor of safety. At fracture, the induced <span class="hlt">strain</span> is inelastic and about an order-of-magnitude greater than designed for maximum expected operational limit. At this extreme <span class="hlt">strained</span> condition, the structure may rotate and displace at the applied verification load such as to unknowingly distort the load transfer into the static test article. Test may result in erroneously accepting a submarginal design or rejecting a reliable one. A technique was developed to identify, monitor, and assess the load transmission error through two back-to-back surface-measured <span class="hlt">strain</span> data. The technique is programmed for expediency and convenience. Though the method was developed to support affordable aerostructures, the method is also applicable for most high-performance air and surface transportation structural systems.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28068587','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28068587"><span>Quantitative assessment of viable cells of Lactobacillus plantarum <span class="hlt">strains</span> in single, dual and multi-<span class="hlt">strain</span> biofilms.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fernández Ramírez, Mónica D; Kostopoulos, Ioannis; Smid, Eddy J; Nierop Groot, Masja N; Abee, Tjakko</p> <p>2017-03-06</p> <p>Biofilms of Lactobacillus plantarum are a potential source for contamination and recontamination of food products. Although biofilms have been mostly studied using single species or even single <span class="hlt">strains</span>, it is conceivable that in a range of environmental settings including food processing areas, biofilms are composed of multiple species with each species represented by multiple <span class="hlt">strains</span>. In this study six spoilage related L. plantarum <span class="hlt">strains</span> FBR1-FBR6 and the model <span class="hlt">strain</span> L. plantarum WCFS1 were characterised in single, dual and multiple <span class="hlt">strain</span> competition models. A quantitative PCR approach was used with added propidium monoazide (PMA) enabling quantification of intact cells in the biofilm, representing the viable cell fraction that determines the food spoilage risk. Our results show that the performance of individual <span class="hlt">strains</span> in multi-<span class="hlt">strain</span> cultures generally correlates with their performance in pure culture, and relative <span class="hlt">strain</span> abundance in multi-<span class="hlt">strain</span> biofilms positively correlated with the relative <span class="hlt">strain</span> abundance in suspended (planktonic) cultures. Performance of individual <span class="hlt">strains</span> in dual-<span class="hlt">strain</span> biofilms was highly influenced by the presence of the secondary <span class="hlt">strain</span>, and in most cases no correlation between the relative contributions of viable planktonic cells and viable cells in the biofilm was noted. The total biofilm quantified by CV staining of the dual and multi-<span class="hlt">strain</span> biofilms formed was mainly correlated to CV values of the dominant <span class="hlt">strain</span> obtained in single <span class="hlt">strain</span> studies. However, the combination of <span class="hlt">strain</span> FBR5 and <span class="hlt">strain</span> WCFS1 showed significantly higher CV values compared to the individual performances of both <span class="hlt">strains</span> indicating that total biofilm formation was higher in this specific condition. Notably, L. plantarum FBR5 was able to outgrow all other <span class="hlt">strains</span> and showed the highest relative abundance in dual and multi-<span class="hlt">strain</span> biofilms. All the dual and multi-<span class="hlt">strain</span> biofilms contained a considerable number of viable cells, representing a potential</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19880012129','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19880012129"><span>Controlled-<span class="hlt">strain</span> rate tests at very low <span class="hlt">strain</span> rates of 2618 aluminum at 200 C</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ding, J. L.; Lee, S. R.</p> <p>1988-01-01</p> <p>Constant <span class="hlt">strain</span> rate tests and constant load creep tests were performed on 2618 aluminum at 200 C. The <span class="hlt">strain</span> rates used in the constant <span class="hlt">strain</span> rate tests were 10 to the minus 6, 10 to the minus 7, 10 to the minum 8, and 10 to the minus 9/sec. Due to the fact that the <span class="hlt">strain</span> rates in both tests were comparable to each other, the similarities between them can therefore be studied. It was concluded that metals are essentially rate sensitive at elevated temperatures. The traditional definition of creep and plasticity used in the classical creep analysis is actually a reflection of the material behavior under different loading conditions. A constitutive equation based on the test data under one loading condition should work well for other loading conditions as long as the <span class="hlt">strain</span> rates are in the same range as those under which the material constants are determined.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ChPhB..24c6801S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ChPhB..24c6801S"><span><span class="hlt">Strain</span> analysis of free-standing <span class="hlt">strained</span> silicon-on-insulator nanomembrane</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sun, Gao-Di; Dong, Lin-Xi; Xue, Zhong-Ying; Chen, Da; Guo, Qing-Lei; Mu, Zhi-Qiang</p> <p>2015-03-01</p> <p>Based on the ultra-thin <span class="hlt">strained</span> silicon-on-insulator (sSOI) technology, by creatively using a hydrofluoric acid (HF) vapor corrosion system to dry etch the SiO2 layer, a large area of suspended <span class="hlt">strained</span> silicon (sSi) nanomembrane with uniform <span class="hlt">strain</span> distribution is fabricated. The <span class="hlt">strain</span> state in the implemented nanomembrane is comprehensively analyzed by using an UV-Raman spectrometer with different laser powers. The results show that the inherent <span class="hlt">strain</span> is preserved while there are artificial Raman shifts induced by the heat effect, which is proportional to the laser power. The suspended sSOI nanomembrane will be an important material for future novel high-performance devices. Project supported by the National Natural Science Foundation of China (Grant Nos. 61376117 and 61107025) and the Zhejiang Provincial Natural Science Foundation of China (Grant No. LY13F040004).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4982289','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4982289"><span>Complete Genome Sequence of the Oncolytic Sendai virus <span class="hlt">Strain</span> Moscow</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Zainutdinov, Sergei S.; Tikunov, Artem Y.; Matveeva, Olga V.</p> <p>2016-01-01</p> <p>We report here the complete genome sequence of Sendai virus Moscow <span class="hlt">strain</span>. Anecdotal evidence for the efficacy of oncolytic virotherapy exists for this <span class="hlt">strain</span>. The RNA genome of the Moscow <span class="hlt">strain</span> is 15,384 nucleotides in length and differs from the nearest <span class="hlt">strain</span>, BB1, by 18 nucleotides and 11 amino acids. PMID:27516510</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19740031112&hterms=magnesium+oxide&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmagnesium%2Boxide','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19740031112&hterms=magnesium+oxide&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmagnesium%2Boxide"><span>Dynamic <span class="hlt">strain</span> aging in magnesium oxide single crystals</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Srinivasan, M.; Stoebe, T. G.</p> <p>1973-01-01</p> <p><span class="hlt">Strain</span> rate change transients are considered together with aspects of serrated flow, questions of flow stress and work hardening during dynamic <span class="hlt">strain</span> aging, and time, temperature, and prestrain dependence of <span class="hlt">strain</span> aging. On continuing the deformation process after aging for certain periods of time for a particular <span class="hlt">strain</span>, a subsidiary load drop is sometimes observed in addition to the main yield drops.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26769927','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26769927"><span>Draft Genome Sequences of Achromobacter piechaudii GCS2, Agrobacterium sp. <span class="hlt">Strain</span> SUL3, Microbacterium sp. <span class="hlt">Strain</span> GCS4, Shinella sp. <span class="hlt">Strain</span> GWS1, and Shinella sp. <span class="hlt">Strain</span> SUS2 Isolated from Consortium with the Hydrocarbon-Producing Alga Botryococcus braunii.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jones, Katy J; Moore, Karen; Sambles, Christine; Love, John; Studholme, David J; Aves, Stephen J</p> <p>2016-01-14</p> <p>A variety of bacteria associate with the hydrocarbon-producing microalga Botryococcus braunii, some of which may influence its growth. We report here the genome sequences for Achromobacter piechaudii GCS2, Agrobacterium sp. <span class="hlt">strain</span> SUL3, Microbacterium sp. <span class="hlt">strain</span> GCS4, and Shinella sp. <span class="hlt">strains</span> GWS1 and SUS2, isolated from a laboratory culture of B. braunii, race B, <span class="hlt">strain</span> Guadeloupe.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20000024984&hterms=new+madrid+seismic+zone&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dnew%2Bmadrid%2Bseismic%2Bzone','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20000024984&hterms=new+madrid+seismic+zone&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dnew%2Bmadrid%2Bseismic%2Bzone"><span>Stresses and <span class="hlt">Strains</span> within the "Stable" North American Plate</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Engeln, Joe</p> <p>1995-01-01</p> <p>This paper presents a final report on "Stresses and <span class="hlt">Strains</span> within the "Stable" North American Plate". The topics include: 1) <span class="hlt">Strain</span> rates near the New Madrid seismic zone; 2) Signal Processing of intermediate term data; and 3) Transform fault stresses and <span class="hlt">strains</span>. The paper also includes graphs of the stress and <span class="hlt">strain</span> distributions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=287069','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=287069"><span>Pheromonal divergence between two <span class="hlt">strains</span> of Spodoptera frugiperda</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Abstract- Spodoptera frugiperda consists of two genetically and behaviorally different <span class="hlt">strains</span>, the corn- and the rice-<span class="hlt">strain</span>, which seem to be in the process of sympatric speciation. We investigated the role of <span class="hlt">strain</span>-specific sexual communication as a prezygotic mating barrier between both <span class="hlt">strains</span>...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22328768','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22328768"><span>Genome sequence of Brevibacillus laterosporus <span class="hlt">strain</span> GI-9.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sharma, Vikas; Singh, Pradip K; Midha, Samriti; Ranjan, Manish; Korpole, Suresh; Patil, Prabhu B</p> <p>2012-03-01</p> <p>We report the 5.18-Mb genome sequence of Brevibacillus laterosporus <span class="hlt">strain</span> GI-9, isolated from a subsurface soil sample during a screen for novel <span class="hlt">strains</span> producing antimicrobial compounds. The draft genome of this <span class="hlt">strain</span> will aid in biotechnological exploitation and comparative genomics of Brevibacillus laterosporus <span class="hlt">strains</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3768671','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3768671"><span>Ciprofloxacin susceptibility reduction of Salmonella <span class="hlt">strains</span> isolated from outbreaks</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Souza, Roberta B.; Ferrari, Rafaela G.; Magnani, Marciane; Kottwitz, Luciana B. M.; Alcocer, Iliana; Tognim, Maria Cristina B.; Oliveira, Tereza C. R. M.</p> <p>2010-01-01</p> <p>The antimicrobial susceptibility of 212 Salmonella <span class="hlt">strains</span> isolated from patients and foods was evaluated and 45% were found to be resistant to nalidixic acid. Nalidixic acid resistant <span class="hlt">strains</span> showed a higher minimal inhibitory concentration for ciprofloxacin than sensitive <span class="hlt">strains</span>. During the study an increase of <span class="hlt">strains</span> with reduced susceptibility to ciprofloxacin was also observed. PMID:24031522</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20375237','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20375237"><span>Cyclomodulins in urosepsis <span class="hlt">strains</span> of Escherichia coli.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dubois, Damien; Delmas, Julien; Cady, Anne; Robin, Frédéric; Sivignon, Adeline; Oswald, Eric; Bonnet, Richard</p> <p>2010-06-01</p> <p>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 <span class="hlt">strains</span> 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 <span class="hlt">strains</span>. It emerged from this study that <span class="hlt">strains</span> harboring the pks island and the cnf1 gene (i) were strongly associated with the B2 phylogroup (P, <0.001), (ii) frequently harbored both toxin-encoded genes in phylogroup B2 (33%), and (iii) were predictive of a urosepsis origin (P, <0.001 to 0.005). However, the prevalences of the pks island among phylogroup B2 <span class="hlt">strains</span>, in contrast to those of the cnf1 gene, were not significantly different between fecal and urosepsis groups, suggesting that the pks island is more important for the colonization process and the cnf1 gene for virulence. pks- or cnf1-harboring <span class="hlt">strains</span> were significantly associated with susceptibility to antibiotics (amoxicillin, cotrimoxazole, and quinolones [P, <0.001 to 0.043]). Otherwise, only 6% and 1% of all <span class="hlt">strains</span> harbored the cdtB and cif genes, respectively, with no particular distribution by phylogenetic background, antimicrobial susceptibility, or clinical origin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFM.S21A2372B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFM.S21A2372B"><span>Modeling <span class="hlt">Strains</span> Associated with Fluid Extraction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barbour, A. J.; Agnew, D. C.; Wyatt, F. K.</p> <p>2013-12-01</p> <p>A class of <span class="hlt">strain</span> signals found in data from a number of borehole strainmeters in the Plate Boundary Observatory network is believed to be associated with pumping of nearby water wells. In order to test the connection between fluid extraction and deformation, we have collected a multi- year record of the pump activity at two actively-pumped wells near the pair of strainmeters at the Pathfinder Ranch, a summer camp located in the Garner Valley in southern California. The data we have collected indicate strong correlations between (1) times of fluid extraction and the onset of significant <span class="hlt">strain</span> and pore-fluid pressure changes, and (2) cumulative extraction volumes and the sizes of the pressure and <span class="hlt">strain</span> perturbations. In order to model these observations, we use a sum of K autoregressive models to create a statistical description of the effect, and a poroelastic model to create a physical description. We show that for K = 2 the mixture model adequately preserves both long- and short-term effects, and can be used to construct a ';correction series' from the binary pumping series in a numerically efficient manner. Spatiotemporal <span class="hlt">strain</span> and pore- fluid pressure fields associated with episodes of fluid extraction are simulated in a layered, radially extensive poroelastic medium. Based on the interpretations of our parameter exploration, the simplest model which fits the observed <span class="hlt">strains</span> and pressures is a two layer model where rigid bedrock having relatively high diffusivity is overlain by roughly 100 meters of alluvium having slightly higher diffusivity and behaving as an unconfined aquifer system. The lack of a strong contrast in diffusivity between lithologic units suggests that the bedrock material has a relatively high density of hydraulically conductive fractures; borehole logging data and drillers' logs corroborate this. Further, the requirement that both layers have high conductivity helps explain the relatively low sensitivity of the aquifer system to dynamic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3224125','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3224125"><span>Genome organization of epidemic Acinetobacter baumannii <span class="hlt">strains</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p></p> <p>2011-01-01</p> <p>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 <span class="hlt">strains</span>. The occurrence of epidemics caused by multi-drug resistant <span class="hlt">strains</span> 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 <span class="hlt">strains</span> 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 <span class="hlt">strains</span> 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 <span class="hlt">strains</span>. The analysis of a collection of epidemic A. baumannii <span class="hlt">strains</span> 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. PMID:21985032</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26655590','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26655590"><span>Ultrasound <span class="hlt">strain</span> mapping of Achilles tendon compressive <span class="hlt">strain</span> patterns during dorsiflexion.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chimenti, Ruth L; Flemister, A Samuel; Ketz, John; Bucklin, Mary; Buckley, Mark R; Richards, Michael S</p> <p>2016-01-04</p> <p>Heel lifts are commonly prescribed to patients with Achilles tendinopathy, yet little is known about the effect on tendon compressive <span class="hlt">strain</span>. The purposes of the current study were to (1) develop a valid and reliable ultrasound elastography technique and algorithm to measure compressive <span class="hlt">strain</span> of human Achilles tendon in vivo, (2) examine the effects of ankle dorsiflexion (lowering via controlled removal of a heel lift and partial squat) on compressive <span class="hlt">strain</span> of the Achilles tendon insertion and (3) examine the relative compressive <span class="hlt">strain</span> between the deep and superficial regions of the Achilles tendon insertion. All tasks started in a position equivalent to standing with a 30mm heel lift. An ultrasound transducer positioned over the Achilles tendon insertion was used to capture radiofrequency images. A non-rigid image registration-based algorithm was used to estimate compressive <span class="hlt">strain</span> of the tendon, which was divided into 2 regions (superficial, deep). The bland-Altman test and intraclass correlation coefficient were used to test validity and reliability. One-way repeated measures ANOVA was used to compare compressive <span class="hlt">strain</span> between regions and across tasks. Compressive <span class="hlt">strain</span> was accurately and reliably (ICC>0.75) quantified. There was greater compressive <span class="hlt">strain</span> during the combined task of lowering and partial squat compared to the lowering (P=.001) and partial squat (P<.001) tasks separately. There was greater compressive <span class="hlt">strain</span> in the deep region of the tendon compared to the superficial for all tasks (P=.001). While these findings need to be examined in a pathological population, heel lifts may reduce tendon compressive <span class="hlt">strain</span> during daily activities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2293154','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=2293154"><span>Development of a <span class="hlt">Strain</span>-Specific Molecular Method for Quantitating Individual Campylobacter <span class="hlt">Strains</span> in Mixed Populations▿</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Elvers, Karen T.; Helps, Christopher R.; Wassenaar, Trudy M.; Allen, Vivien M.; Newell, Diane G.</p> <p>2008-01-01</p> <p>The identification of sites resulting in cross-contamination of poultry flocks in the abattoir and determination of the survival and persistence of campylobacters at these sites are essential for the development of intervention strategies aimed at reducing the microbial burden on poultry at retail. A novel molecule-based method, using <span class="hlt">strain</span>- and genus-specific oligonucleotide probes, was developed to detect and enumerate specific campylobacter <span class="hlt">strains</span> in mixed populations. <span class="hlt">Strain</span>-specific oligonucleotide probes were designed for the short variable regions (SVR) of the flaA gene in individual Campylobacter jejuni <span class="hlt">strains</span>. A 16S rRNA Campylobacter genus-specific probe was also used. Both types of probes were used to investigate populations of campylobacters by colony lift hybridization. The specificity and proof of principle of the method were tested using <span class="hlt">strains</span> with closely related SVR sequences and mixtures of these <span class="hlt">strains</span>. Colony lifts of campylobacters were hybridized sequentially with up to two labeled <span class="hlt">strain</span>-specific probes, followed by the generic 16S rRNA probe. SVR probes were highly specific, differentiating down to 1 nucleotide in the target sequence, and were sufficiently sensitive to detect colonies of a single <span class="hlt">strain</span> in a mixed population. The 16S rRNA probe detected all Campylobacter spp. tested but not closely related species, such as Arcobacter skirrowi and Helicobacter pullorum. Preliminary field studies demonstrated the application of this technique to target <span class="hlt">strains</span> isolated from poultry transport crate wash tank water. This method is quantitative, sensitive, and highly specific and allows the identification and enumeration of selected <span class="hlt">strains</span> among all of the campylobacters in environmental samples. PMID:18281428</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007ApPhL..91y1912C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007ApPhL..91y1912C"><span><span class="hlt">Strain</span> responsive concave and convex microlens arrays</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chandra, Dinesh; Yang, Shu; Lin, Pei-Chun</p> <p>2007-12-01</p> <p>We report the fabrication of single-component, <span class="hlt">strain</span> responsive microlens arrays with real-time tunability. The concave lens array is fabricated by patterning hard oxide layer on a bidirectionally prestretched soft elastomer, poly(dimethylsiloxane) (PDMS) followed by confined buckling upon release of the prestrain. The convex microlens array is replica molded from the concave lenses in PDMS. Due to difference in lens formation mechanisms, the two types of lenses show different tunable range of focal length in response to the applied <span class="hlt">strain</span>: large focal length change is observed from the concave microlens array, whereas that from the convex microlens array is much smaller.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750023410','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750023410"><span>NASTRAN modifications for recovering <span class="hlt">strains</span> and curvatures</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hennrich, C. W.</p> <p>1975-01-01</p> <p>Modifications to the NASTRAN structural analysis computer program are described. The modifications allow the recovery of <span class="hlt">strain</span> and curvature data for the general two-dimensional elements, in addition to the usual stress data. Option features allow the transformation of the <span class="hlt">strain</span>/curvature (or stress) data to a common coordinate system and representation at the grid points of the structural model rather than at the conventional element center locations. Usage information is provided which will allow present users of NASTRAN to easily utilize the new capability.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730009719','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730009719"><span>Development of high temperature <span class="hlt">strain</span> gages</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lemcoe, M. M.</p> <p>1973-01-01</p> <p>High temperature electric resistance wire <span class="hlt">strain</span> gages were developed and evaluated for use at temperatures exceeding 922 K (1200 F). A special high temperature <span class="hlt">strain</span> gage alloy (Fe-25Cr-7.5A1), designated BCL-3, was used to fabricate the gages. Pertinent gage characteristics were determined at temperatures up to 1255 K (1800 F). The results of the evaluation were reported in graphical and tabular form. It was concluded that the gages will perform satisfactorily at temperatures to at least 1089 K (1500 F) for at least one hour.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22267707','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22267707"><span>Tensile <span class="hlt">strain</span> mapping in flat germanium membranes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Rhead, S. D. Halpin, J. E.; Myronov, M.; Patchett, D. H.; Allred, P. S.; Wilson, N. R.; Leadley, D. R.; Shah, V. A.; Kachkanov, V.; Dolbnya, I. P.; Reparaz, J. S.; Sotomayor Torres, C. M.</p> <p>2014-04-28</p> <p>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 <span class="hlt">strain</span> distribution, thickness, and crystalline tilt of the membrane was obtained. We are able to detect a systematic <span class="hlt">strain</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/920878','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/920878"><span>Enabling <span class="hlt">Strain</span> Hardening Simulations with Dislocation Dynamics</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Arsenlis, A; Cai, W</p> <p>2006-12-20</p> <p>Numerical algorithms for discrete dislocation dynamics simulations are investigated for the purpose of enabling <span class="hlt">strain</span> hardening simulations of single crystals on massively parallel computers. The algorithms investigated include the /(N) calculation of forces, the equations of motion, time integration, adaptive mesh refinement, the treatment of dislocation core reactions, and the dynamic distribution of work on parallel computers. A simulation integrating all of these algorithmic elements using the Parallel Dislocation Simulator (ParaDiS) code is performed to understand their behavior in concert, and evaluate the overall numerical performance of dislocation dynamics simulations and their ability to accumulate percents of plastic <span class="hlt">strain</span>.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/840807','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/840807"><span>Traumatic injuries: office treatment of <span class="hlt">strain</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ryan, A J</p> <p>1977-03-01</p> <p><span class="hlt">Strain</span>, defined as trauma to a musculotendinous unit, is characterized by pain, muscle spasm, swelling, and loss of range of motion. Conservative treatment consists of rest and elevation of the affected muscle, application of ice and compression, active and passive stretching, and resisted motion exercises. If rupture of muscle and fascia is extensive, surgery may be required. Chronic <span class="hlt">strain</span> may result from repeated injuries. It is usually treated with rest and administration of an anti-inflammatory agent, such as oxyphenbutazone or a corticosteroid preparation. In the event that this regimen does not provide relief from pain and disability, surgery may be necessary.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19860025310&hterms=contour&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dcontour','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19860025310&hterms=contour&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dcontour"><span>Shear-<span class="hlt">strain</span> contours from moire interferometry</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Post, D.; Czarnek, R.; Joh, D.</p> <p>1985-01-01</p> <p>The development of whole-field contour maps of shear <span class="hlt">strains</span> gamma (xy), derived from displacement fields obtained by moire interferometry with 2400 lines/mm, is described. The use of mechanical differentiation to obtain cross-derivatives of displacements and the use of graphical additive moire to sum the cross-derivatives are explained. Quantitative analysis in the small-<span class="hlt">strain</span> domain is possible because of the high sensitivity of moire interferometry. The applicability of this technique is shown by the testing of a short epoxy beam under three-point bending.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930022369','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930022369"><span>Progress in speckle-shift <span class="hlt">strain</span> measurement</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lant, Christian T.; Barranger, John P.; Oberle, Lawrence G.; Greer, Lawrence C., III</p> <p>1991-01-01</p> <p>The Instrumentation and Control Technology Division of the Lewis Research Center has been developing an in-house capability to make one dimensional and two dimensional optical <span class="hlt">strain</span> measurements on high temperature test specimens. The measurements are based on a two-beam speckle-shift technique. The development of composite materials for use in high temperature applications is generating interest in using the speckle-shift technique to measure <span class="hlt">strains</span> on small diameter fibers and wires of various compositions. The results of preliminary speckle correlation tests on wire and fiber specimens are covered, and the advanced system currently under development is described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JMPSo..87..177C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JMPSo..87..177C"><span>Cells as <span class="hlt">strain</span>-cued automata</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cox, Brian N.; Snead, Malcolm L.</p> <p>2016-02-01</p> <p>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 <span class="hlt">strain</span> fields that arise from their individual or collective motions. An autonomous cell's response to <span class="hlt">strain</span> 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 <span class="hlt">strain</span>-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 <span class="hlt">strain</span> 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 <span class="hlt">strains</span> they themselves create in the host population as they invade it: analysis shows that the <span class="hlt">strain</span> 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</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017MeScT..28a5106K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017MeScT..28a5106K"><span>Atmospheric corrosion sensor based on <span class="hlt">strain</span> measurement</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kasai, Naoya; Hiroki, Masatoshi; Yamada, Toshirou; Kihira, Hiroshi; Matsuoka, Kazumi; Kuriyama, Yukihisa; Okazaki, Shinji</p> <p>2017-01-01</p> <p>In this paper, an in situ atmospheric corrosion sensor based on <span class="hlt">strain</span> 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 <span class="hlt">strain</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19960018814&hterms=mcneill&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmcneill','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19960018814&hterms=mcneill&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dmcneill"><span>Computing Displacements And <span class="hlt">Strains</span> From Video Images</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Russell, Samuel S.; Mcneill, Stephen R.; Lansing, Matthew D.</p> <p>1996-01-01</p> <p>Subpixel digital video image correlation (SDVIC) technique for measuring in-plane displacements on surfaces of objects under loads, without contact. Used for analyses of experimental research specimens or actual service structures of virtually any size or material. Only minimal preparation of test objects needed, and no need to isolate test objects from minor vibrations or fluctuating temperatures. Technique implemented by SDVIC software, producing color-graduated, full-field representations of in-plane displacements and partial derivatives with respect to position along both principal directions in each image plane. From representations, linear <span class="hlt">strains</span>, shear <span class="hlt">strains</span>, and rotation fields determined. Written in C language.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AIPC.1389.1228E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AIPC.1389.1228E"><span>Ecoepidemics with Two <span class="hlt">Strains</span>: Diseased Prey.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Elena, Elisa; Grammauro, Maria; Venturino, Ezio</p> <p>2011-09-01</p> <p>In this work we present a minimal model for an ecoepidemic situation with two diseases affecting the prey population. The main assumptions are the following ones. The predators recognize and hunt only the healthy prey. An infected prey of one <span class="hlt">strain</span> becomes immune to the other one. The major finding shows that the two <span class="hlt">strains</span> cannot simultaneously thrive in the system, contrary to the standard assumptions in epidemiology. But this rather unexpected and remarkable result, paralleling another one when the epidemics affects the predators, is most likely due to the assumptions made.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=243828','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=243828"><span>Comparison of Ethanol Production by Different Zymomonas <span class="hlt">Strains</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Skotnicki, M. L.; Lee, K. J.; Tribe, D. E.; Rogers, P. L.</p> <p>1981-01-01</p> <p>A comparison of the rates of growth and ethanol production by 11 different <span class="hlt">strains</span> of Zymomonas revealed a wide range of characteristics, with some <span class="hlt">strains</span> being more tolerant of high sugar or ethanol concentrations and high incubation temperatures than others. Some <span class="hlt">strains</span> were unable to utilize sucrose; others produced large amounts of levan, and one <span class="hlt">strain</span> grew well but produced no levan. One <span class="hlt">strain</span>, CP4, was considerably better in all respects than most of the other <span class="hlt">strains</span> and was chosen as a starting <span class="hlt">strain</span> for genetic improvement of ethanol production. PMID:16345753</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SPIE.9798E..37N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SPIE.9798E..37N"><span>Novel pre-<span class="hlt">strain</span> method for dielectric electroactive polymers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Newell, Brittany; Krutz, Gary; Stewart, Frank; Pascal, Kevin</p> <p>2016-04-01</p> <p>Dielectric electroactive polymers have demonstrated their significant potential in a variety of applications due to their material strength and elastomeric material properties. Mechanical pre-<span class="hlt">strain</span> has been shown to enhance material actuation potential significantly. However, with this enhancement comes sacrifices. Mechanical pre-<span class="hlt">strain</span> imposes a stiff mechanical boundary on the dielectric material in order to maintain the <span class="hlt">strain</span>. In this research, investigations were made into the mechanisms of mechanical pre-<span class="hlt">strain</span> and into alternate pre-<span class="hlt">strain</span> methods. These studies discovered alternate methods capable of producing enhanced pre-<span class="hlt">strains</span> and final actuation without the addition of the solid <span class="hlt">strain</span> boundary.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1388493','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=1388493"><span>Variability among Rhizobium <span class="hlt">Strains</span> Originating from Nodules of Vicia faba</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>van Berkum, P.; Beyene, D.; Vera, F. T.; Keyser, H. H.</p> <p>1995-01-01</p> <p>Rhizobium <span class="hlt">strains</span> from nodules of Vicia faba were diverse in plasmid content and serology. Results of multilocus gel electrophoresis and restriction fragment length polymorphism indicated several deep chromosomal lineages among the <span class="hlt">strains</span>. Linkage disequilibrium among the chromosomal types was detected and may have reflected variation of Rhizobium <span class="hlt">strains</span> in the different geographical locations from which the <span class="hlt">strains</span> originated. An investigation of pea <span class="hlt">strains</span> with antibodies prepared against fava bean <span class="hlt">strains</span> and restriction fragment length polymorphism analyses, targeting DNA regions coding for rRNA and nodulation, indicated that Rhizobium <span class="hlt">strains</span> from V. faba nodules were distinguishable from those from Pisum sativum, V. villosa, and Trifolium spp. PMID:16535075</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25528607','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25528607"><span>Influence of ferrous ions on extracellular polymeric substances content and sludge dewaterability during bioleaching.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wong, Jonathan W C; Zhou, Jun; Kurade, Mayur B; Murugesan, Kumarasamy</p> <p>2015-03-01</p> <p>Pretreatment of activated sludge with sulfuric acid and bioleaching using <span class="hlt">Acidithiobacillus</span> <span class="hlt">ferrooxidans</span> along with addition of Fe(2+) on sludge dewaterability was investigated. The sludge dewatering efficiency in terms of capillary suction time (CST) and specific resistant to filtration (SRF) was increased with a decrease in sludge pH. A pH of 2.67 was found to be optimum for dewatering, at which 81% and 63% reduction of CST and SRF were achieved, respectively. The dewaterability of sludge was enhanced after the addition of Fe(2+) and A. <span class="hlt">ferrooxidans</span>. Ideal concentration of Fe(2+) was 2 g/L for sludge dewaterability, which showed 96% and 88% reduction in CST and SRF, respectively. In the control sludge, maximum part of the biopolymeric macromolecules was contributing by the tightly bound extracellular polymeric substances (TB-EPS). At optimum Fe(2+) concentration, total EPS was reduced by 73%, enhancing sludge dewaterability. Bioleaching conducted by A. <span class="hlt">ferrooxidans</span> could solubilized 88% Cu and 99% Zn within 120 h.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19353890','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19353890"><span>[Effects of different iron concentrations on the growths of a unicellular <span class="hlt">strain</span> and a colonial <span class="hlt">strain</span> of Microcystis aeruginosa].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Wang, Yu-wen; Li, Jian-hong; Fu, Lu; Wu, Min; Weng, Yong-ping; Zhou, Yao-ming</p> <p>2009-01-01</p> <p>We investigated the growth, photosynthetic efficiency, siderophore production and iron accumulation of two <span class="hlt">strains</span> of M. aeruginosa, a unicellular <span class="hlt">strain</span> M. aeruginosa PCC7806 and a colonial <span class="hlt">strain</span> M. aeruginosa XW01, under iron-limited and iron-replete conditions. The identities of ITS and fur gene sequences of two <span class="hlt">strains</span> were 95% and 98% respectively.That implied the two <span class="hlt">strains</span> should be close relatives. Results showed the growths of two <span class="hlt">strains</span> were severely inhibited under an iron-limited condition. The unicellular <span class="hlt">strain</span> died in 6 days,whereas the colonial <span class="hlt">strain</span> could maintain a weak growth in 10 days under the iron-limited condition. PSII maximum light energy transformation (Fv/Fm) of the colonial <span class="hlt">strain</span> and the unicellular <span class="hlt">strain</span> were 0.182 +/- 0.014 and 0.160 +/- 0.017, respectively. The colonial <span class="hlt">strain</span> displayed a higher photosynthetic oxygen evolution than the unicellular <span class="hlt">strain</span>. Two <span class="hlt">strains</span> could produce siderophores, which were hydroxamate type. The colonial <span class="hlt">strain</span> produced more siderophores than unicellular <span class="hlt">strain</span> under the iron-limited condition.Iron contents of two <span class="hlt">strains</span> were less than 1/3 cultured in the iron-limited condition than in iron-replete condition, but no obvious difference appeared between the two <span class="hlt">strains</span>. Our result demonstrated that the colonial <span class="hlt">strain</span> have a stronger endurance than unicellular <span class="hlt">strain</span> under the iron-limited condition. As two <span class="hlt">strains</span> had almost same abilities of iron accumulation, the other physiological mechanisms in the unicellular <span class="hlt">strain</span> should be more sensitive to lower iron level.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA208826','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA208826"><span>High-<span class="hlt">Strain</span> Rate Testing of Gun Propellants</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>1988-12-01</p> <p>specimen is loaded beyond the elastic range. Instrumentation of the bars allows recording of the <span class="hlt">strain</span> history in the bars during the test event. The...<span class="hlt">strain</span> history on the input bar gives a record of the <span class="hlt">strain</span> rate history in the sample. )The output bar <span class="hlt">strain</span> history is proportional to the stress... history in the sample.) The data were compared to the results reported in the literature of earlier high <span class="hlt">strain</span> rate tests on the same propellants. The</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA573739','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA573739"><span>High <span class="hlt">Strain</span> Rate Tensile and Compressive Effects in Glassy Polymers</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2013-02-08</p> <p>polymers under high <span class="hlt">strain</span> rates has been determined in compression. Some research programs have studied the combined effects of temperature and <span class="hlt">strain</span> rate...glassy polymers to high <span class="hlt">strain</span> rate loading in compression. More recently, research programs that study the combined effects of temperature and <span class="hlt">strain</span>...Force Materiel Command  United States Air Force  Eglin Air Force Base AFRL-RW-EG-TP-2013-006 High <span class="hlt">Strain</span> Rate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5289684','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5289684"><span>Genome Sequences of Bacillus thuringiensis Serovar kurstaki <span class="hlt">Strain</span> BP865 and B. thuringiensis Serovar aizawai <span class="hlt">Strain</span> HD-133</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Jeong, Haeyoung</p> <p>2017-01-01</p> <p>ABSTRACT We report the draft genome sequences of two insecticidal <span class="hlt">strains</span> against lepidopteran pests, Bacillus thuringiensis serovar kurstaki <span class="hlt">strain</span> BP865, an isolate from the South Korean phylloplane, and <span class="hlt">strain</span> HD-133, a reference <span class="hlt">strain</span> of B. thuringiensis serovar aizawai. PMID:28153898</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26186451','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26186451"><span>Multiple Comparison Analysis of Two New Genomic Sequences of ILTV <span class="hlt">Strains</span> from China with Other <span class="hlt">Strains</span> from Different Geographic Regions.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhao, Yan; Kong, Congcong; Wang, Yunfeng</p> <p>2015-01-01</p> <p>To date, twenty complete genome sequences of ILTV <span class="hlt">strains</span> have been published in GenBank, including one <span class="hlt">strain</span> from China, and nineteen <span class="hlt">strains</span> from Australian and the United States. To investigate the genomic information on ILTVs from different geographic regions, two additional individual complete genome sequences of WG and K317 <span class="hlt">strains</span> from China were determined. The genomes of WG and K317 <span class="hlt">strains</span> were 153,505 and 153,639 bp in length, respectively. Alignments performed on the amino acid sequences of the twelve glycoproteins showed that 13 out of 116 mutational sites were present only among the Chinese <span class="hlt">strain</span> WG and the Australian <span class="hlt">strains</span> SA2 and A20. The phylogenetic tree analysis suggested that the WG <span class="hlt">strain</span> established close relationships with the Australian <span class="hlt">strain</span> SA2. The recombination events were detected and confirmed in different subregions of the WG <span class="hlt">strain</span> with the sequences of SA2 and K317 <span class="hlt">strains</span> as parental. In this study, two new complete genome sequences of Chinese ILTV <span class="hlt">strains</span> were used in comparative analysis with other complete genome sequences of ILTV <span class="hlt">strains</span> from China, the United States, and Australia. The analysis of genome comparison, phylogenetic trees, and recombination events showed close relationships among the Chinese <span class="hlt">strain</span> WG and the Australian <span class="hlt">strains</span> SA2. The information of the two new complete genome sequences from China will help to facilitate the analysis of phylogenetic relationships and the molecular differences among ILTV <span class="hlt">strains</span> from different geographic regions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25660626','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25660626"><span>Perceptual <span class="hlt">strain</span> index for heat <span class="hlt">strain</span> assessment in an experimental study: an application to construction workers.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yang, Y; Chan, Albert P C</p> <p>2015-02-01</p> <p>Although the physiological <span class="hlt">strain</span> 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 <span class="hlt">strain</span> index (PeSI) has been proposed as a user-friendly and practical indicator for heat <span class="hlt">strain</span>. However, the application of this index in assessing the heat <span class="hlt">strain</span> 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 <span class="hlt">strain</span> 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 <span class="hlt">strain</span>. Thus, the PeSI offers considerable promise for heat <span class="hlt">strain</span> assessment under simulated working conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4106073','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4106073"><span>Probiotic Potential of Lactobacillus <span class="hlt">Strains</span> with Antimicrobial Activity against Some Human Pathogenic <span class="hlt">Strains</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Shokryazdan, Parisa; Sieo, Chin Chin; Kalavathy, Ramasamy; Liang, Juan Boo; Alitheen, Noorjahan Banu; Faseleh Jahromi, Mohammad; Ho, Yin Wan</p> <p>2014-01-01</p> <p>The objective of this study was to isolate, identify, and characterize some lactic acid bacterial <span class="hlt">strains</span> from human milk, infant feces, and fermented grapes and dates, as potential probiotics with antimicrobial activity against some human pathogenic <span class="hlt">strains</span>. One hundred and forty bacterial <span class="hlt">strains</span> 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 <span class="hlt">strains</span> of humans, and most of them exhibited stronger antimicrobial activity than the reference <span class="hlt">strain</span> L. casei Shirota. Thus, the nine Lactobacillus <span class="hlt">strains</span> could be considered as potential antimicrobial probiotic <span class="hlt">strains</span> against human pathogens and should be further studied for their human health benefits. PMID:25105147</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910010090','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910010090"><span>The apparent <span class="hlt">strain</span> stability and repeatability of a BCL3 resistance <span class="hlt">strain</span> gage</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lei, Jih-Fen</p> <p>1991-01-01</p> <p>Experiments were conducted at NASA-Lewis to study the effect of microstructural instability on the apparent <span class="hlt">strain</span> stability and reproducibility of a BCL3 resistance <span class="hlt">strain</span> gage. The resistance drift of the gage at various temperatures in the phase transition temperature range (PTTR) was measured. The effects of the heating and cooling rates with which the gage passed through the PTTR on the apparent <span class="hlt">strain</span> characteristics of the gage were also studied. BCL3 gage, like other Fe-Cr-Al based gages, exhibited apparent <span class="hlt">strain</span> instability in the temperature range of 700 to 1100 F due to the reversible microstructural transition the gage materials experienced in this temperature range. The BCL3 gage had a maximum apparent <span class="hlt">strain</span> drift in the neighborhood of 770 F with an average drift rate of approx. -440 microstrain/hr in 2 hrs. The use of the BCL3 gage as well as other Fe-Cl-Al based gages for static <span class="hlt">strain</span> measurements within the PTTR should be avoided unless the time durations in the PTTR are small enough to introduce a neglible drift. The microstructure transition that the BCL3 gage underwent occurred in the temperature range of 750 to 1050 F during heating and around 1000 to 800 F during cooling. The heating rate, and, in particular, the cooling rate with which the gage passed through the PTTR affected the shape and the repeatability of the apparent <span class="hlt">strain</span> curve of the gage.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010Nanot..21m4013M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010Nanot..21m4013M"><span>Nanoscale patterning induced <span class="hlt">strain</span> redistribution in ultrathin <span class="hlt">strained</span> Si layers on oxide</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Moutanabbir, O.; Reiche, M.; Hähnel, A.; Erfurth, W.; Gösele, U.; Motohashi, M.; Tarun, A.; Hayazawa, N.; Kawata, S.</p> <p>2010-04-01</p> <p>We present a comparative study of the influence of the thickness on the <span class="hlt">strain</span> behavior upon nanoscale patterning of ultrathin <span class="hlt">strained</span> Si layers directly on oxide. The <span class="hlt">strained</span> layers were grown on a SiGe virtual substrate and transferred onto a SiO2/Si substrate using wafer bonding and hydrogen ion induced exfoliation. The post-patterning <span class="hlt">strain</span> was evaluated using UV micro-Raman spectroscopy for thin (20 nm) and thick (60 nm) nanostructures with lateral dimensions in the range of 80-400 nm. We found that about 40-50% of the initial <span class="hlt">strain</span> is maintained in the 20 nm thick nanostructures, whereas this fraction drops significantly to ~ 2-20% for the 60 nm thick ones. This phenomenon of free surface induced relaxation is described using detailed three-dimensional finite element simulations. The simulated <span class="hlt">strain</span> 3D maps confirm the limited relaxation in thin nanostructures. This result has direct implications for the fabrication and manipulation of <span class="hlt">strained</span> Si nanodevices.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23045489','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23045489"><span>Genomic comparison of Kingella kingae <span class="hlt">strains</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Fournier, Pierre-Edouard; Rouli, Laetitia; El Karkouri, Khalid; Nguyen, Thi-Tien; Yagupsky, Pablo; Raoult, Didier</p> <p>2012-11-01</p> <p>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 <span class="hlt">strain</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EPJWC..2602006G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EPJWC..2602006G"><span>High <span class="hlt">strain</span> rate behaviour of polypropylene microfoams</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gómez-del Río, T.; Garrido, M. A.; Rodríguez, J.; Arencón, D.; Martínez, A. B.</p> <p>2012-08-01</p> <p>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 <span class="hlt">strain</span> 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 <span class="hlt">strain</span> rates (0.001 to 3000 s-1) in order to show the effects of the processing parameters and <span class="hlt">strain</span> rate on the mechanical properties. High <span class="hlt">strain</span> rate tests were performed using a Split Hopkinson Pressure Bar apparatus (SHPB). Polypropylene and polyethylene-ethylene block copolymer foams of various densities were considered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA573778','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA573778"><span>Rapid Parallel Screening for <span class="hlt">Strain</span> Optimization</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2013-02-19</p> <p>reporting period, we have completed screening for microbial growth and nearly finished the proposed sequencing. Sequencing would have been completed... microbial <span class="hlt">strains</span> that produce industrially relevant biochemicals routine. Recent synthetic biology techniques can make billions of variant cells...industrially relevant biomolecules) are identified using microbial growth assays, sequencing, and quantitative PCR (qPCR). To demonstrate that such</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA594001','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA594001"><span>Rapid Parallel Screening for <span class="hlt">Strain</span> Optimization</span></a></p> <p><a target="_blank" href="https://publicaccess.dtic.mil/psm/api/service/search/search">DTIC Science & Technology</a></p> <p></p> <p>2013-11-18</p> <p>engineering of new microbial <span class="hlt">strains</span> that produce industrially relevant biochemicals routine. Recent synthetic biology techniques can make billions of...overproduction of such molecules. Identification and experimental validation of specific sensors is indispensable but current results are promising: 1) most...target chemicals (~80%) readily produce microbial growth, 2) colony morphology, etc., suggests that different target chemicals resulted in the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://eric.ed.gov/?q=merton&pg=2&id=EJ762245','ERIC'); return false;" href="http://eric.ed.gov/?q=merton&pg=2&id=EJ762245"><span>Role <span class="hlt">Strain</span> in University Research Centers</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Boardman, Craig; Bozeman, Barry</p> <p>2007-01-01</p> <p>One way in which university faculty members' professional lives have become more complex with the advent of contemporary university research centers is that many faculty have taken on additional roles. The authors' concern in this article is to determine the extent to which role <span class="hlt">strain</span> is experienced by university faculty members who are…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23385407','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23385407"><span>Thermal <span class="hlt">strain</span> analysis of optic fiber sensors.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Her, Shiuh-Chuan; Huang, Chih-Ying</p> <p>2013-01-31</p> <p>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 <span class="hlt">strain</span> 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 <span class="hlt">strain</span> induced by the host structure is transferred via the adhesive layer and protective coating. In this investigation, an analytical expression of the thermal <span class="hlt">strain</span> and stress in the optical fiber is presented. The theoretical predictions are validated using the finite element method. Numerical results show that the thermal <span class="hlt">strain</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/867538','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/867538"><span>Neutron apparatus for measuring <span class="hlt">strain</span> in composites</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Kupperman, David S.; Majumdar, Saurindranath; Faber, Jr., John F.; Singh, J. P.</p> <p>1990-01-01</p> <p>A method and apparatus for orienting a pulsed neutron source and a multi-angle diffractometer toward a sample of a ceramic-matrix or metal-matrix composite so that the measurement of internal <span class="hlt">strain</span> (from which stress is calculated) is reduced to uncomplicated time-of-flight measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5188875','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/biblio/5188875"><span>Superconducting wire with improved <span class="hlt">strain</span> characteristics</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Luhman, T.; Klamut, C.J.; Suenaga, M.; Welch, D.</p> <p>1979-12-19</p> <p>A superconducting wire comprising a superconducting filament and a beryllium strengthened bronze matrix in which the addition of beryllium to the matrix permits a low volume matrix to exhibit reduced elastic deformation after heat treating which increases the compression of the superconducting filament on cooling and thereby improve the <span class="hlt">strain</span> characteristics of the wire.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/864172','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/864172"><span>Superconducting wire with improved <span class="hlt">strain</span> characteristics</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Luhman, Thomas; Klamut, Carl J.; Suenaga, Masaki; Welch, David</p> <p>1982-01-01</p> <p>A superconducting wire comprising a superconducting filament and a beryllium strengthened bronze matrix in which the addition of beryllium to the matrix permits a low volume matrix to exhibit reduced elastic deformation after heat treating which increases the compression of the superconducting filament on cooling and thereby improve the <span class="hlt">strain</span> characteristics of the wire.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/864302','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/864302"><span>Superconducting wire with improved <span class="hlt">strain</span> characteristics</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Luhman, Thomas; Klamut, Carl J.; Suenaga, Masaki; Welch, David</p> <p>1982-01-01</p> <p>A superconducting wire comprising a superconducting filament and a beryllium strengthened bronze matrix in which the addition of beryllium to the matrix permits a low volume matrix to exhibit reduced elastic deformation after heat treating which increases the compression of the superconducting filament on cooling and thereby improves the <span class="hlt">strain</span> characteristics of the wire.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..MARJ32004F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..MARJ32004F"><span>Charge and <span class="hlt">Strain</span> Control of Interface Magnetism</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>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.</p> <p>2015-03-01</p> <p>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 <span class="hlt">strain</span> and hole-doping, we performed neutron scattering experiments of La0.8Sr0.2MnO3 films grown on Nb-doped STO in which bending <span class="hlt">strain</span> (via 4-point bending jig) or electric field (via parallel plate capacitor) was applied to the films. We observed that bending <span class="hlt">strain</span> affects the saturation magnetization of the LSMO film, whereas electric field affects the remanent magnetization of the film. These observations suggest <span class="hlt">strain</span> 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).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19880000040&hterms=hygroscopic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dhygroscopic','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19880000040&hterms=hygroscopic&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dhygroscopic"><span><span class="hlt">Strain</span>-Energy-Release Rates In Delamination</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Raju, I. S.</p> <p>1988-01-01</p> <p>Q3DG computer program developed to perform quasi-three-dimensional stress analysis of composite laminates containing delaminations. Calculates <span class="hlt">strain</span>-energy-release rates for long, rectangular composite laminates containing delaminations and subjected to any combination of mechanical, thermal, and hygroscopic loading. Written in FORTRAN V.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/21506805','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/21506805"><span>Quality Control On <span class="hlt">Strained</span> Semiconductor Devices</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Dommann, Alex; Neels, Antonia</p> <p>2010-11-24</p> <p>New semiconductor devices are based very often on <span class="hlt">strained</span> silicon which promises to squeeze more device performance out of current devices. With <span class="hlt">strained</span> silicon it is possible to get the same device performance using less power. The technique is using <span class="hlt">strain</span> as a 'design element' for silicon to improve the device performance and has become a hot topic in semiconductor research in the past years. However in the same time topics like 'System in Package'(SiP) on thin wafers are getting more and more important. The chips of thin wafers in advanced packaging are extremely sensitive to induced stresses due to packaging issues. If we are using now <span class="hlt">strain</span> as a design element for improving device performance we increase the sensitivity again and therefore also the risk of aging of such SiP's. High Resolution X-ray diffraction (HRXRD) techniques such as Rocking Curves (RC's) and Reciprocal Space Mapping (RSM) are therefore very powerful tools to study the stresses in packaged devices.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Geote..50..336P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Geote..50..336P"><span>Prediction of swelling rocks <span class="hlt">strain</span> in tunneling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Parsapour, D.; Fahimifar, A.</p> <p>2016-05-01</p> <p>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 <span class="hlt">strains</span> as a function of time and stress, swelling <span class="hlt">strains</span> 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 <span class="hlt">strain</span> around tunnels. Evaluating effects of swelling parameters on time-dependent <span class="hlt">strains</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JAP...118l3904D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JAP...118l3904D"><span>High <span class="hlt">strain</span>-rate magnetoelasticity in Galfenol</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Domann, J. P.; Loeffler, C. M.; Martin, B. E.; Carman, G. P.</p> <p>2015-09-01</p> <p>This paper presents the experimental measurements of a highly magnetoelastic material (Galfenol) under impact loading. A Split-Hopkinson Pressure Bar was used to generate compressive stress up to 275 MPa at <span class="hlt">strain</span> rates of either 20/s or 33/s while measuring the stress-<span class="hlt">strain</span> response and change in magnetic flux density due to magnetoelastic coupling. The average Young's modulus (44.85 GPa) was invariant to <span class="hlt">strain</span> rate, with instantaneous stiffness ranging from 25 to 55 GPa. A lumped parameters model simulated the measured pickup coil voltages in response to an applied stress pulse. Fitting the model to the experimental data provided the average piezomagnetic coefficient and relative permeability as functions of field strength. The model suggests magnetoelastic coupling is primarily insensitive to <span class="hlt">strain</span> rates as high as 33/s. Additionally, the lumped parameters model was used to investigate magnetoelastic transducers as potential pulsed power sources. Results show that Galfenol can generate large quantities of instantaneous power (80 MW/m3 ), comparable to explosively driven ferromagnetic pulse generators (500 MW/m3 ). However, this process is much more efficient and can be cyclically carried out in the linear elastic range of the material, in stark contrast with explosively driven pulsed power generators.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=270866','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=270866"><span>Genome sequence of Haemophilus parasuis <span class="hlt">strain</span> 29755</span></a></p> <p><a target="_blank" href="http://www.ars.usda.gov/services/TekTran.htm">Technology Transfer Automated Retrieval System (TEKTRAN)</a></p> <p></p> <p></p> <p>Haemophilus parasuis is a member of the family Pasteurellaceae and is the etiologic agent of Glasser's disease in pigs, a systemic syndrome associated with only a subset of isolates. The genetic basis for virulence and systemic spread of particular H. parasuis isolates is currently unknown. <span class="hlt">Strain</span> 2...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27714887','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27714887"><span>Highly Stretchable, <span class="hlt">Strain</span> Sensing Hydrogel Optical Fibers.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Guo, Jingjing; Liu, Xinyue; Jiang, Nan; Yetisen, Ali K; Yuk, Hyunwoo; Yang, Changxi; Khademhosseini, Ali; Zhao, Xuanhe; Yun, Seok-Hyun</p> <p>2016-12-01</p> <p>A core-clad fiber made of elastic, tough hydrogels is highly stretchable while guiding light. Fluorescent dyes are easily doped into the hydrogel fiber by diffusion. When stretched, the transmission spectrum of the fiber is altered, enabling the <span class="hlt">strain</span> to be measured and also its location.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/scitech/biblio/22300283','SCIGOV-STC'); return false;" href="https://www.osti.gov/scitech/biblio/22300283"><span><span class="hlt">Strain</span> engineering of Dirac cones in graphyne</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Wang, Gaoxue; Kumar, Ashok; Pandey, Ravindra; Si, Mingsu</p> <p>2014-05-26</p> <p>6,6,12-graphyne, one of the two-dimensional carbon allotropes with the rectangular lattice structure, has two kinds of non-equivalent anisotropic Dirac cones in the first Brillouin zone. We show that Dirac cones can be tuned independently by the uniaxial compressive <span class="hlt">strain</span> applied to graphyne, which induces n-type and p-type self-doping effect, by shifting the energy of the Dirac cones in the opposite directions. On the other hand, application of the tensile <span class="hlt">strain</span> results into a transition from gapless to finite gap system for the monolayer. For the AB-stacked bilayer, the results predict tunability of Dirac-cones by in-plane <span class="hlt">strains</span> as well as the <span class="hlt">strain</span> applied perpendicular to the plane. The group velocities of the Dirac cones show enhancement in the resistance anisotropy for bilayer relative to the case of monolayer. Such tunable and direction-dependent electronic properties predicted for 6,6,12-graphyne make it to be competitive for the next-generation electronic devices at nanoscale.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/437675','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/servlets/purl/437675"><span>Characterizing large <span class="hlt">strain</span> crush response of redwood</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Cramer, S.M.; Hermanson, J.C.; McMurtry, W.M.</p> <p>1996-12-01</p> <p>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-<span class="hlt">strain</span> theory for redwood; and to review the literature on <span class="hlt">strain</span>-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-<span class="hlt">strain</span> relationships for redwood. A review of existing literature indicated that <span class="hlt">strain</span>-rate effects cause at most a 20 percent increase in crush stress parallel to grain.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5228237','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5228237"><span>Identification of <span class="hlt">Strain</span>-Specific Sequences That Distinguish a Mycoplasma gallisepticum Vaccine <span class="hlt">Strain</span> from Field Isolates</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Ricketts, Camir; Pickler, Larissa; Maurer, John; Ayyampalayam, Saravanaraj; García, Maricarmen</p> <p>2016-01-01</p> <p>ABSTRACT Despite attempts to control avian mycoplasmosis through management, vaccination, and surveillance, Mycoplasma gallisepticum continues to cause significant morbidity, mortality, and economic losses in poultry production. Live attenuated vaccines are commonly used in the poultry industry to control avian mycoplasmosis; unfortunately, some vaccines may revert to virulence and vaccine <span class="hlt">strains</span> are generally difficult to distinguish from natural field isolates. In order to identify genome differences among vaccine revertants, vaccine <span class="hlt">strains</span>, and field isolates, whole-genome sequencing of the M. gallisepticum vaccine <span class="hlt">strain</span> ts-11 and several “ts-11-like” <span class="hlt">strains</span> isolated from commercial flocks was performed using Illumina and 454 pyrosequencing and the sequenced genomes compared to the M. gallisepticum Rlow reference genome. The collective contigs for each <span class="hlt">strain</span> were annotated using the fully annotated Mycoplasma reference genome. The analysis revealed genetic differences among vlhA alleles, as well as among genes annotated as coding for a cell wall surface anchor protein (mg0377) and a hypothetical protein gene, mg0359, unique to M. gallisepticum ts-11 vaccine <span class="hlt">strain</span>. PCR protocols were designed to target 5 sequences unique to the M. gallisepticum ts-11 <span class="hlt">strain</span>: vlhA3.04a, vlhA3.04b, vlhA3.05, mg0377, and mg0359. All ts-11 isolates were positive for the five gene alleles tested by PCR; however, 5 to 36% of field isolates were also positive for at least one of the alleles tested. A combination of PCR tests for vlhA3.04a, vlhA3.05, and mg0359 was able to distinguish the M. gallisepticum ts-11 vaccine <span class="hlt">strain</span> from field isolates. This method will further supplement current approaches to quickly distinguish M. gallisepticum vaccine <span class="hlt">strains</span> from field isolates. PMID:27847370</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22043083','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22043083"><span><span class="hlt">Strain</span> Hardening and <span class="hlt">Strain</span> Softening of Reversibly Cross-linked Supramolecular Polymer Networks.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xu, Donghua; Craig, Stephen L</p> <p>2011-09-27</p> <p>The large amplitude oscillatory shear behavior of metallo-supramolecular polymer networks formed by adding bis-Pd(II) cross-linkers to poly(4-vinylpyridine) (PVP) in dimethyl sulfoxide (DMSO) solution is reported. The influence of scanning frequency, dissociation rate of cross-linkers, concentration of cross-linkers, and concentration of PVP solution on the large amplitude oscillatory shear behavior is explored. In semidilute unentangled PVP solutions, above a critical scanning frequency, <span class="hlt">strain</span> hardening of both storage moduli and loss moduli is observed. In the semidilute entangled regime of PVP solution, however, <span class="hlt">strain</span> softening is observed for samples with faster cross-linkers (k(d) ∼ 1450 s(-1)), whereas <span class="hlt">strain</span> hardening is observed for samples with slower cross-linkers (k(d) ∼ 17 s(-1)). The mechanism of <span class="hlt">strain</span> hardening is attributed primarily to a <span class="hlt">strain</span>-induced increase in the number of elastically active chains, with possible contributions from non-Gaussian stretching of polymer chains at <span class="hlt">strains</span> approaching network fracture. The divergent <span class="hlt">strain</span> softening of samples with faster cross-linkers in semidilute entangled PVP solutions, relative to the <span class="hlt">strain</span> hardening of samples with slower cross-linkers, is consistent with observed shear thinning/shear thickening behavior reported previously and is attributed to the fact that the average time that a cross-linker remains detached is too short to permit the local relaxation of polymer chain segments that is necessary for a net conversion of elastically inactive to elastically active cross-linkers. These and other observations paint a picture in which <span class="hlt">strain</span> softening and shear thinning arise from the same set of molecular mechanisms, conceptually uniting the two nonlinear responses for this system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MeScT..26e5103W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MeScT..26e5103W"><span>Network of flexible capacitive <span class="hlt">strain</span> gauges for the reconstruction of surface <span class="hlt">strain</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Jingzhe; Song, Chunhui; Saleem, Hussam S.; Downey, Austin; Laflamme, Simon</p> <p>2015-05-01</p> <p>Monitoring of surface <span class="hlt">strain</span> on mesosurfaces is a difficult task, often impeded by the lack of scalability of conventional sensing systems. A solution is to deploy large networks of flexible <span class="hlt">strain</span> gauges, a type of large area electronics. The authors have recently proposed a soft elastomeric capacitor (SEC) as an economical skin-type solution for large-scale deployment onto mesosurfaces. The sensing principle is based on a measurable change in the sensor’s capacitance upon <span class="hlt">strain</span>. In this paper, we study the performance of the sensor at reconstructing surface <span class="hlt">strain</span> map and deflection shapes. A particular feature of the sensor is that it measures surface <span class="hlt">strain</span> additively, because it is not utilized within a Wheatstone bridge configuration. An algorithm is proposed to decompose the additive in-plane <span class="hlt">strain</span> measurements from the SEC into principal components. The algorithm consists of assuming a polynomial shape function, and deriving the <span class="hlt">strain</span> based on Kirchhoff plate theory. A least-squares estimator (LSE) is used to minimize the error between the assumed model and the SEC signals after the enforcement of boundary conditions. Numerical simulations are conducted on a symmetric rectangular cantilever thin plate under symmetric and asymmetric static loads to demonstrate the accuracy and real-time applicability of the algorithm. The performance of the algorithm is further examined on an asymmetric cantilever laminated thin plate constituted with orthotropic materials mimicking a wind turbine blade, and subjected to a non-stationary wind load. Results from simulations show good performance of the algorithm at reconstructing the surface <span class="hlt">strain</span> maps for both in-plane principal <span class="hlt">strain</span> components, and that it can be applied in real time. However, its performance can be improved by strengthening assumptions on boundary conditions. The algorithm exhibits robustness in performance with respect to load and noise in signals, except when most of the sensors’ signals are</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004PhST..114...22W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004PhST..114...22W"><span>Silicon Germanium <span class="hlt">Strained</span> Layers and Heterostructures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Willander, M.; Nur, O.; Jain, S. C.</p> <p>2004-01-01</p> <p>The integration of <span class="hlt">strained</span>-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 <span class="hlt">strained</span>-Si1 xGex based optical devices into standard Silicon technology. The impact of integrating <span class="hlt">strained</span> 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 <span class="hlt">strain</span> 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 <span class="hlt">strained</span>-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 <span class="hlt">strained</span> 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 <span class="hlt">strained</span>-Si1 xGex highly doped base have lead to optimize the performance of the bipolar technology for many applications easily. The strategies of design</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160011958','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160011958"><span>Unsteady Aerodynamic Force Sensing from Measured <span class="hlt">Strain</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Pak, Chan-Gi</p> <p>2016-01-01</p> <p>A simple approach for computing unsteady aerodynamic forces from simulated measured <span class="hlt">strain</span> data is proposed in this study. First, the deflection and slope of the structure are computed from the unsteady <span class="hlt">strain</span> 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. A cantilevered rectangular wing built and tested at the NASA Langley Research Center (Hampton, Virginia, USA) in 1959 is used to validate the simple approach. Unsteady aerodynamic forces as well as wing deflections, velocities, accelerations, and <span class="hlt">strains</span> are computed using the CFL3D computational fluid dynamics (CFD) code and an MSC/NASTRAN code (MSC Software Corporation, Newport Beach, California, USA), and these CFL3D-based results are assumed as measured quantities. Based on the measured <span class="hlt">strains</span>, wing deflections, velocities, accelerations, and aerodynamic forces are computed using the proposed approach. These computed deflections, velocities, accelerations, and unsteady aerodynamic forces are compared with the CFL3D/NASTRAN-based results. In general, computed aerodynamic forces based on the lifting surface theory in subsonic speeds are in good agreement with the target aerodynamic forces generated using CFL3D code with the Euler equation. Excellent aeroelastic responses are obtained even with unsteady <span class="hlt">strain</span> data under the signal to noise ratio of -9.8dB. The deflections, velocities, and accelerations at each sensor location are independent of structural and aerodynamic models. Therefore, the distributed <span class="hlt">strain</span> data together with the current proposed approaches can be used as distributed deflection</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19910064276&hterms=wire+resistance+temperature&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dwire%2Bresistance%2Btemperature','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19910064276&hterms=wire+resistance+temperature&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dwire%2Bresistance%2Btemperature"><span>A resistance <span class="hlt">strain</span> gage with repeatable apparent <span class="hlt">strain</span> to 800 C</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lei, J.-F.</p> <p>1991-01-01</p> <p>Experimental PdCr temperature-compensated resistance static-<span class="hlt">strain</span> gages are described. The gages are developed in both fine-wire and thin-film forms. It is found that a PdCr wire <span class="hlt">strain</span> gage coated with a flame-sprayed mixture of alumina and 4 wt pct zirconia demonstrates the smallest variation in and the best repeatability of apparent <span class="hlt">strain</span> among the existing gages used at temperatures up to 800 C. Results of preliminary tests indicate uncompensated uncoated thin-film gages have potential usefulness at temperatures up to 1000 C.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992ApOpt..31.2987F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992ApOpt..31.2987F"><span>Simultaneous interferometric and polarimetric <span class="hlt">strain</span> measurements on composites using a fiber-optic <span class="hlt">strain</span> gauge</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fuerstenau, N.; Schmidt, W.; Goetting, H.-C.</p> <p>1992-06-01</p> <p>A fiberoptic Michelson interferometer is used for remote sensing of the bending-induced surface <span class="hlt">strain</span> of plates made from carbon-fiber composites. The double-polarization method is used for eliminating the ambiguity of fringe counting. Simultaneous measurement of the birefringence-dependent phase offset yields an additional analog (polarimetric) signal, which allows for initialization of the incremental readout. The measured dependence of surface <span class="hlt">strain</span> on plate bending agrees with the theoretically expected linear relationship, and it agrees with the gauge sensitivity published by Valis et al. (1989). The observed hysteresis and temperature sensitivity are significantly smaller than the same effects in an electrical <span class="hlt">strain</span> gauge.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EPJWC..9404006H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EPJWC..9404006H"><span><span class="hlt">Strain</span> rate effects for spallation of concrete</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Häussler-Combe, Ulrich; Panteki, Evmorfia; Kühn, Tino</p> <p>2015-09-01</p> <p>Appropriate triaxial constitutive laws are the key for a realistic simulation of high speed dynamics of concrete. The <span class="hlt">strain</span> 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 <span class="hlt">strain</span> 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 <span class="hlt">strain</span> rate effects [1]. In contrast to other approaches the dynamic strength increase is not directly coupled to <span class="hlt">strain</span> 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 <span class="hlt">strain</span> effects [3].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AGUFM.G53C..02W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AGUFM.G53C..02W"><span>Searching for <span class="hlt">Strain</span> Transients in PBO data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wei, M.; McGuire, J. J.; Richardson, E.; Kraft, R. L.; Hardwig, M. D.</p> <p>2011-12-01</p> <p>We applied a recently developed <span class="hlt">strain</span> anomaly detector, the Network Stain Filter [Ohtani et al., 2010], to the continuous GPS datasets from the PBO in Alaska and Salton Trough. The strategy of the filter is to find spatially and temporally coherent signals by processing data from the entire network simultaneously. Compared to previous Network Inversion Filter [Segall and Matthews, 1997], the new detector does not require the knowledge of potential sources, which can be either unknown and/or very numerous in a large tectonically active area. At Alaska, we find a <span class="hlt">strain</span> anomaly between Kodiak Island and Kenai Peninsula that began in early 2010. There are earthquakes that are likely related to the <span class="hlt">strain</span> anomaly. The physical interpretation of the <span class="hlt">strain</span> anomaly is still in progress. The secular motion since 2006 that PBO recorded is consistent with a model that consist of two locked patches on Kodiak Island and Kenai Peninsula and a creeping patch near Cook Inlet as determined earlier by Zweck et al. [2002]. Seasonal signals dominate in the data and are highly correlated between stations in the horizontal components. The reason for this correlation in seasonal term azimuths between stations is not clear. At Salton Trough, the post-seismic deformation of the 2010 Mw 7.2 El Mayor Earthquake dominates the transient signals. The maximum post-seismic slip recorded by the GPS is 23 mm during 1.5 years after the earthquake (Site ID P494). Additionally, we are exploring using InSAR data as a complimentary method for detecting <span class="hlt">strain</span> anomaly in areas with shallow sources, such as in the Salton Trough. A creep event on the Superstition Hills Fault in October 2006 has been observed by InSAR but missed by nearby GPS stations due to low amplitude at the location [Wei et al., 2009].</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/23575634','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/23575634"><span>Unexpected <span class="hlt">strain</span>-stiffening in crystalline solids.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Jiang, Chao; Srinivasan, Srivilliputhur G</p> <p>2013-04-18</p> <p><span class="hlt">Strain</span>-stiffening--an increase in material stiffness at large <span class="hlt">strains</span>--is a vital mechanism by which many soft biological materials thwart excessive deformation to protect tissue integrity. Understanding the fundamental science of <span class="hlt">strain</span>-stiffening and incorporating this concept into the design of metals and ceramics for advanced applications is an attractive prospect. Using cementite (Fe3C) and aluminium borocarbide (Al3BC3) as prototypes, here we show via quantum-mechanical calculations that <span class="hlt">strain</span>-stiffening also occurs, surprisingly, in simple inorganic crystalline solids and confers exceptionally high strengths to these two solids, which have anomalously low resistance to deformation near equilibrium. For Fe3C and Al3BC3, their ideal shear strength to shear modulus ratios attain remarkably high values of 1.14 and 1.34 along the (010)[001] and slip systems, respectively. These values are more than seven times larger than the original Frenkel value of 1/2π (refs 4, 5) and are the highest yet reported for crystalline solids. The extraordinary stiffening of Fe3C arises from the <span class="hlt">strain</span>-induced reversible 'cross-linking' between weakly coupled edge- and corner-sharing Fe6C slabs. This new bond formation creates a strong, three-dimensional covalent bond network that resists large shear deformation. Unlike Fe3C, no new bond forms in Al3BC3 but stiffening still occurs because strong repulsion between Al and B in a compressed Al-B bond unsettles the existing covalent bond network. These discoveries challenge the conventional wisdom that large shear modulus is a reliable predictor of hardness and strength of materials, and provide new lessons for materials selection and design.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21185052','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21185052"><span>Colloid <span class="hlt">straining</span> within saturated heterogeneous porous media.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Porubcan, Alexis A; Xu, Shangping</p> <p>2011-02-01</p> <p>The transport of 0.46 μm, 2.94 μm, 5.1 μm and 6.06 μm latex particles in heterogeneous porous media prepared from the mixing of 0.78 mm, 0.46 mm and 0.23 mm quartz sands was investigated through column transport experiments. It was observed that the 0.46 μm particles traveled conservatively within the heterogeneous porous media, suggesting that under the experimental conditions employed in this research the strong repulsive interactions between the negatively charged latex particles and the clean quartz sands led to minimal colloid immobilization due to physicochemical filtration. The immobilization of the 2.94 μm, 5.1 μm and 6.06 μm latex particles was thus attributed to colloid <span class="hlt">straining</span>. Experimental results showed that the <span class="hlt">straining</span> of colloidal particles within heterogeneous sand mixtures increased when the fraction of finer sands increased. The mathematical model that was developed and tested based on results obtained using uniform sands (Xu et al., 2006) was found to be able to describe colloid <span class="hlt">straining</span> within heterogeneous porous media. Examination of the relationship between the best-fit values of the clean-bed <span class="hlt">straining</span> rate coefficients (k(0)) and the ratio of colloid diameter (d(p)) and sand grain size (d(g)) indicated that when number-average sizes were used to represent the size of the heterogeneous porous media, there existed a consistent relationship for both uniform sands and heterogeneous sand mixtures. Similarly, the use of the number-averaged sizes for the heterogeneous porous media produced a uniform relationship between the colloid <span class="hlt">straining</span> capacity term (λ) and the ratio of d(p)/d(g) for all the sand treatments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18051229','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18051229"><span>[Behavior of Argentine lymphocytic choriomeningitis virus <span class="hlt">strains</span> in rodents].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Saavedra, María del Cármen; Ambrosio, Ana M; Riera, Laura; Sabattini, Marta S</p> <p>2007-01-01</p> <p>The activity of LCM virus was first reported in Argentina at the beginning of the seventies and only five <span class="hlt">strains</span> have been isolated from rodents Mus domesticus and two from humans. The objective of this paper was to find differential biological characteristics of Argentine <span class="hlt">strains</span> of LCM virus comparing them in relation to the historical <span class="hlt">strains</span> WE and Armstrong. Regarding the results obtained in tissue culture, when L 929 cells were used, plaque forming units (PFU) were obtained with human and mouse <span class="hlt">strains</span>, whilst on Vero cells only human <span class="hlt">strains</span> developed PFU. Differentials characteristics of historical and Argentine <span class="hlt">strain</span>'s plates were not found, neither differences related to the <span class="hlt">strain</span>'s origin. Neither historical nor Argentine <span class="hlt">strains</span> were lethal to new-born mice giving a persistent infection, that was demonstrated when we inoculated new-born mouse by intracranial route with different <span class="hlt">strains</span> of LCM virus and virus was isolated from brains harvested at different days post inoculation. The only exception was Cba An 13065 <span class="hlt">strain</span> that exhibited virulence in new-born mice, only with 0.026 PFU was obtained 1 DL50. All the <span class="hlt">strains</span> resulted lethal to adult mice. The mouse <span class="hlt">strains</span> were more virulent than human <span class="hlt">strains</span>, being Cba An 13065 the most virulent. These results demonstrate a different behavior in tissue culture between human and mouse <span class="hlt">strains</span> and allow the identification of virulence markers by intracranial inoculation into new-born or adult mice.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26968547','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26968547"><span>The influence of acute unloading on left ventricular <span class="hlt">strain</span> and <span class="hlt">strain</span> rate by speckle tracking echocardiography in a porcine model.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Dahle, Geir Olav; Stangeland, Lodve; Moen, Christian Arvei; Salminen, Pirjo-Riitta; Haaverstad, Rune; Matre, Knut; Grong, Ketil</p> <p>2016-05-15</p> <p>Noninvasive measurements of myocardial <span class="hlt">strain</span> and <span class="hlt">strain</span> 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 <span class="hlt">strain</span> and <span class="hlt">strain</span> 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 <span class="hlt">strain</span> and <span class="hlt">strain</span> 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 <span class="hlt">strain</span> and <span class="hlt">strain</span> rate were sensitive to unloading of the left ventricle (P < 0.001), but the load dependency for <span class="hlt">strain</span> rate was modest compared with <span class="hlt">strain</span>. Changes in longitudinal and circumferential <span class="hlt">strain</span> correlated more strongly to changes in end-diastolic volume (r = -0.86 and r = -0.72) than did radial <span class="hlt">strain</span> (r = 0.35). Longitudinal, circumferential, and radial <span class="hlt">strain</span> significantly correlated with LV-dP/dtmax (r = -0.53, r = -0.46, and r = 0.86), whereas only radial <span class="hlt">strain</span> correlated with PRSW (r = 0.55). <span class="hlt">Strain</span> rate in the longitudinal, circumferential and radial direction significantly correlated with both PRSW (r = -0.64, r = -0.58, and r = 0.74) and LV-dP/dtmax (r = -0.95, r = -0.70, and r = 0.85). In conclusion, the speckle tracking echocardiography-derived <span class="hlt">strain</span> rate is more robust to dynamic ventricular unloading than <span class="hlt">strain</span>. Longitudinal and circumferential <span class="hlt">strain</span> could not predict load-independent contractility. <span class="hlt">Strain</span> rates, and especially in the radial direction, are good predictors of preload-independent inotropic markers derived from conductance catheter.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5041503','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5041503"><span>Brucella abortus <span class="hlt">Strain</span> 2308 Wisconsin Genome: Importance of the Definition of Reference <span class="hlt">Strains</span></span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>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</p> <p>2016-01-01</p> <p>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 <span class="hlt">strains</span> as canonical models to understand the mechanisms underlying host pathogen interactions. We performed whole genome sequencing analysis of the reference <span class="hlt">strain</span> 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 <span class="hlt">strain</span>. Considering the outcome of high resolution genomic techniques in the bacteriology field, the conventional concept of <span class="hlt">strain</span> definition needs to be revised. PMID:27746773</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20625472','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20625472"><span>Gendered Responses to Serious <span class="hlt">Strain</span>: The Argument for a General <span class="hlt">Strain</span> Theory of Deviance.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Kaufman, Joanne M</p> <p>2009-09-01</p> <p>This paper expands and builds on newer avenues in research on gender and general <span class="hlt">strain</span> theory (GST). I accomplish this by focusing on serious <span class="hlt">strains</span> 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 <span class="hlt">strains</span> on both types of negative emotions and different forms of deviance for males and females. However, the experience of serious <span class="hlt">strain</span>, 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27746773','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27746773"><span>Brucella abortus <span class="hlt">Strain</span> 2308 Wisconsin Genome: Importance of the Definition of Reference <span class="hlt">Strains</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>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</p> <p>2016-01-01</p> <p>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 <span class="hlt">strains</span> as canonical models to understand the mechanisms underlying host pathogen interactions. We performed whole genome sequencing analysis of the reference <span class="hlt">strain</span> 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 <span class="hlt">strain</span>. Considering the outcome of high resolution genomic techniques in the bacteriology field, the conventional concept of <span class="hlt">strain</span> definition needs to be revised.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3192842','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3192842"><span>A Wide Extent of Inter-<span class="hlt">Strain</span> Diversity in Virulent and Vaccine <span class="hlt">Strains</span> of Alphaherpesviruses</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Szpara, Moriah L.; Tafuri, Yolanda R.; Parsons, Lance; Shamim, S. Rafi; Verstrepen, Kevin J.; Legendre, Matthieu; Enquist, L. W.</p> <p>2011-01-01</p> <p>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 <span class="hlt">strain</span> 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 <span class="hlt">strain</span>. We find many previously unknown coding differences between PRV Bartha and the virulent <span class="hlt">strains</span>, including changes to the fusion proteins gH and gB, and over forty other viral proteins. Inter-<span class="hlt">strain</span> 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 <span class="hlt">strains</span>. We find SSR length variation between different isolates of PRV and HSV-1, which may provide a new mechanism for phenotypic variation between <span class="hlt">strains</span>. Finally, we detected a small number of polymorphic bases within each plaque-purified PRV <span class="hlt">strain</span>, 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 limited sequence</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930038316&hterms=wire+resistance+temperature&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dwire%2Bresistance%2Btemperature','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930038316&hterms=wire+resistance+temperature&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dwire%2Bresistance%2Btemperature"><span>High temperature static <span class="hlt">strain</span> measurement with an electrical resistance <span class="hlt">strain</span> gage</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lei, Jih-Fen</p> <p>1992-01-01</p> <p>An electrical resistance <span class="hlt">strain</span> gage that can supply accurate static <span class="hlt">strain</span> 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.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4445032','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4445032"><span>The genome of Shigella dysenteriae <span class="hlt">strain</span> Sd1617 comparison to representative <span class="hlt">strains</span> in evaluating pathogenesis</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Vongsawan, Ajchara A.; Kapatral, Vinayak; Vaisvil, Benjamin; Burd, Henry; Serichantalergs, Oralak; Venkatesan, Malabi M.; Mason, Carl J.</p> <p>2015-01-01</p> <p>We sequenced and analyzed Shigella dysenteriae <span class="hlt">strain</span> Sd1617 serotype 1 that is widely used as model <span class="hlt">strain</span> for vaccine design, trials and research. A combination of next-generation sequencing platforms and assembly yielded two contigs representing a chromosome size of 4.34 Mb and the large virulence plasmid of 177 kb. This genome sequence is compared with other Shigella genomes in order to understand gene complexity and pathogenic factors. PMID:25743074</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EPJB...89..227S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EPJB...89..227S"><span>Effects of <span class="hlt">strain</span> on shot noise properties in graphene superlattices</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sattari, Farhad; Mirershadi, Soghra</p> <p>2016-10-01</p> <p>In this paper the transmission and the shot noise properties through the <span class="hlt">strain</span>-induced graphene superlattices are studied. It is found that for the zigzag direction <span class="hlt">strain</span> the Fano factor shows a peak at new Dirac-like point and the position of the new Dirac point varies against the <span class="hlt">strain</span>. Also, Fano factor has an oscillatory behavior with respect to <span class="hlt">strain</span> strength and the oscillation period decreases by increasing the number of barriers. However, for the armchair direction <span class="hlt">strain</span> the transmission can be blocked by the electric barrier and the Fano factor approaches 1, this is different from the zigzag direction <span class="hlt">strain</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MSSP...60..485P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MSSP...60..485P"><span>Generating <span class="hlt">strain</span> signals under consideration of road surface profiles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Putra, T. E.; Abdullah, S.; Schramm, D.; Nuawi, M. Z.; Bruckmann, T.</p> <p>2015-08-01</p> <p>The current study aimed to develop the mechanism for generating <span class="hlt">strain</span> signal utilising computer-based simulation. The <span class="hlt">strain</span> data, caused by the acceleration, were undertaken from a fatigue data acquisition involving car movements. Using a mathematical model, the measured <span class="hlt">strain</span> signals yielded to acceleration data used to describe the bumpiness of road surfaces. The acceleration signals were considered as an external disturbance on generating <span class="hlt">strain</span> signals. Based on this comparison, both the actual and simulated <span class="hlt">strain</span> data have similar pattern. The results are expected to provide new knowledge to generate a <span class="hlt">strain</span> signal via a simulation.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <center> <div class="footer-extlink text-muted"><small>Some links on this page may take you to non-federal websites. 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