WorldWideScience

Sample records for non-o1 non-o139 strains

  1. [TYPING OF VIBRIO CHOLERAE NON O1/NON O139 STRAINS, ISOLATED IN ROSTOV REGION IN 2014].

    Science.gov (United States)

    Selyanskaya, N A; Arkhangelskaya, I V; Vodopianov, A S; Vodopianov, S O; Kruglikov, V D; Vodyanitskaya, S Yu; Verkina, L M; Nepomnyaschaya, N B

    2016-01-01

    Comparative study of antibiotics resistance and VNTR-typing of Vibrio cholerae non O1/ non O139 strains, isolated on the territory of Rostov region in 2014. Antibioticogramms of strains were determined by serial dilution method in dense nutrient medium according to MG 4.2.2495-09 (2009). Pheno-, sero- and VNTR-typing was carried out by conventional-methods. The studied strains belonged to V. cholerae species, did not agglutinate with O1 and O139 sera, were atoxigenic hemolysis-positive, did not contain genes of cholera toxin and toxin-coregulating pili of adhesion, contained genes of hemagglutinin/protease, protease PrtV, collagenase, cytotonic factor Cef, outer membrane protein-OmpW, tol- and -vps-clusters, regulatory genes toxR and hapR. Antibioticogramms of the strains have shown the presence of cultures, resistant to ampicillin, ceftazidime-furazolidone, trimethoprim/sulfamethoxazole with intermediate resistance to streptomycin, kanamycin, gentamycin, amikacin, netilmicin, Approximately 20% of isolates had multiple drug resistance. Data of VNTR- and genotyping confirmed a possibility of water transmission route of the infection. Execution of monitoring of cultures from environmental samples is necessary for timely detection of genetic characteristics, antibiotics resistance.

  2. Ultrastructural Changes in the Intestine of Suckling Rabbits Infected with Cholerogenic and Non-Cholerogenic nonO1/nonO139 Vibrio cholerae Strains.

    Science.gov (United States)

    Monakhova, E V; Fedorenko, G M; Mazrukho, A B; Bardakhch'yan, E A

    2015-09-01

    We performed an electron microscopic study of the small intestine of suckling rabbits infected with cholerogenic and non-cholerogenic strains nonO1/nonO139 Vibrio cholerae. Cholerogenic strain induced mostly hydropic degeneration of the epithelium typical of cholera toxin effect, while non-cholerogenic strain induced the formation of lacunae along the borders of adjacent epithelial cells typical of hemagglutinin/protease effect. In both cases, reduction of microvilli, destruction of intracellular organelles, two types of mitochondrial reaction (condensation and swelling with destruction of cristae), appearance of myelin figures, defects in the capillary walls, and activation of pinocytosis were observed. These data confirm our previous assumption on interchangeability of different pathogenic factors of Vibrio cholerae, including nonO1/nonO139 strains.

  3. Novel cholix toxin variants, ADP-ribosylating toxins in Vibrio cholerae non-O1/non-O139 strains, and their pathogenicity.

    Science.gov (United States)

    Awasthi, Sharda Prasad; Asakura, Masahiro; Chowdhury, Nityananda; Neogi, Sucharit Basu; Hinenoya, Atsushi; Golbar, Hossain M; Yamate, Jyoji; Arakawa, Eiji; Tada, Toshiji; Ramamurthy, T; Yamasaki, Shinji

    2013-02-01

    Cholix toxin (ChxA) is a recently discovered exotoxin in Vibrio cholerae which has been characterized as a third member of the eukaryotic elongation factor 2-specific ADP-ribosyltransferase toxins, in addition to exotoxin A of Pseudomonas aeruginosa and diphtheria toxin of Corynebacterium diphtheriae. These toxins consist of three characteristic domains for receptor binding, translocation, and catalysis. However, there is little information about the prevalence of chxA and its genetic variations and pathogenic mechanisms. In this study, we screened the chxA gene in a large number (n = 765) of V. cholerae strains and observed its presence exclusively in non-O1/non-O139 strains (27.0%; 53 of 196) and not in O1 (n = 485) or O139 (n = 84). Sequencing of these 53 chxA genes generated 29 subtypes which were grouped into three clusters designated chxA I, chxA II, and chxA III. chxA I belongs to the prototype, while chxA II and chxA III are newly discovered variants. ChxA II and ChxA III had unique receptor binding and catalytic domains, respectively, in comparison to ChxA I. Recombinant ChxA I (rChxA I) and rChxA II but not rChxA III showed variable cytotoxic effects on different eukaryotic cells. Although rChxA II was more lethal to mice than rChxA I when injected intravenously, no enterotoxicity of any rChxA was observed in a rabbit ileal loop test. Hepatocytes showed coagulation necrosis in rChxA I- or rChxA II-treated mice, seemingly the major target for ChxA. The present study illustrates the potential of ChxA as an important virulence factor in non-O1/non-O139 V. cholerae, which may be associated with extraintestinal infections rather than enterotoxicity.

  4. [Evaluation of toxin producing abilities of non-O1/non-O139 serogroup Vibrio cholerae isolated from humans].

    Science.gov (United States)

    Telesmanich, N R; Akulova, M V; Lomov, Iu M; Alekseeva, L P; Kruglikova, V D; Agafonova, V V; Tatarenko, O A; Evdokimova, V V

    2011-01-01

    Determination of non-O1/non-O139 Vibrio cholerae toxin (CT) gene expression by using EIA, and biological effect of non-O1/non-O139 V. cholerae supernatant on cell cultures evaluation. 39 V. cholerae strains from various serological groups were studied. Hemolytic activity of strains was determined by using Greig test, and cholera toxin production--in GM1-EIA and in continuous cell lines by registering cytotonic, cytotoxic and proteolitic effect. GM1-EIA method does not detect CT production in 29 museum strains of non-O1/non-O139 V. cholerae in vitro. CT was detected only in 1 non-O1/non-O139 V. cholerae strain supernatant with OD = 0.577 that is substantially lower than in O1 V. cholerae strains (OD = 2.176). In cell cultures non-O1/non-O139 V. cholerae supernatants diluted to 1:100 caused elongation only in single cells. Cytological model is a more sensitive technique to evaluate toxin producing abilities of non-O1/non-O139 V. cholerae strains and is appropriate for use.

  5. Non-O1, non-O139 Vibrio cholerae bacteremic skin and soft tissue infections.

    Science.gov (United States)

    Maraki, Sofia; Christidou, Athanasia; Anastasaki, Maria; Scoulica, Efstathia

    2016-01-01

    Non-O1, non-O139 Vibrio cholerae can cause sporadic cases of gastroenteritis and extra-intestinal invasive infections, following exposure to contaminated seawater or freshwater or after consumption of raw seafood. Bacteremic infections with skin and soft tissue manifestations are uncommon and in most cases are associated with liver cirrhosis, haematologic malignancies, diabetes mellitus and other immunosuppressed conditions. The medical literature was reviewed and we found 47 published cases of non-O1, non-O139 Vibrio cholerae bacteremic skin and soft tissue infections. A fatal case of bacteremia with bullous cellulitis in a 43-year-old patient with liver cirrhosis is described, which is the first reported in Greece. From January 1974 to May 2015, a total of 48 patients with non-O1, non-O139 Vibrio cholerae bacteremia with skin and soft tissue infections were reported. Males predominated. Liver cirrhosis, chronic liver disease and alcohol abuse were common comorbidities. The soft tissue lesions most commonly described were localised cellulitis, with or without bullous and haemorrhagic lesions (66.7%), while necrotising fasciitis was more rare (29.2%). Of the 48 patients with non-O1, non-O139 V. cholerae bacteremic skin and soft tissue infections, 20 (41.7%) died despite treatment. Although rarely encountered, non-O1, non-O139 Vibrio cholerae should be included in the differential diagnosis of bacteremic skin and soft tissue infections in patients with underlying illnesses and epidemiologic risk factors. Timely and appropriate antibiotic and surgical treatments are important in the management of the infection.

  6. Vibrio cholerae non-O1, non-O139 serogroups and cholera-like diarrhea, Kolkata, India.

    Science.gov (United States)

    Dutta, Devarati; Chowdhury, Goutam; Pazhani, Gururaja P; Guin, Sucharita; Dutta, Sanjucta; Ghosh, Santanu; Rajendran, K; Nandy, Ranjan K; Mukhopadhyay, Asish K; Bhattacharya, Mihir K; Mitra, Utpala; Takeda, Yoshifumi; Nair, G Balakrish; Ramamurthy, Thandavarayan

    2013-03-01

    We identified 281 Vibrio cholerae non-O1, non-O139 strains from patients with diarrhea in Kolkata, India. Cholera-like diarrhea was the major symptom (66.0%); some patients (20.3%) had severe dehydration. These strains lacked the ctxA gene but many had hlyA, rtxA, and rtxC genes. Pulsed-field gel electrophoresis showed no genetic link among strains.

  7. Isolation of New Delhi metallo-β-lactamase 1-producing Vibrio cholerae non-O1, non-O139 strain carrying ctxA, st and hly genes in southern Vietnam.

    Science.gov (United States)

    Diep, Tai The; Nguyen, Nhi Thi Ngoc; Nguyen, Thi Ngoc Cat; An, Huy Khac; Nguyen, Truong Quang; Nguyen, Vu Hoang; Nguyen, Thuong Van; Nguyen, Thu Ngoc Anh; Izumiya, Hidemasa; Ohnishi, Makoto; Yamashiro, Tetsu; Nguyen, Lan Thi Phuong

    2015-05-01

    Vibrio cholerae non-O1, non-O139 (VC_NAG) organisms are universally present in the aquatic environment and regarded as non-pathogenic bacteria. However, considering that they do occasionally induce gastroenteritis, a study of their virulence and antibiotic resistance genes is important. The presence of enteropathogenic genes, including ctxA, VC_NAG-specific heat-stable toxin gene (st), hemolysin (hly), and zona occludens toxin (zot) was determined by PCR in 100 VC_NAG strains isolated in southern Vietnam in 2010-2013 from 94 environmental and six human origins. These 100 VC_NAG strains were also tested phenotypically and genotypically for the presence of the New Delhi metallo-β-lactamase (NDM-1). Of the 100 VC_NAG strains tested, six were positive for ctxA; five from the environment and one of human origin. The st gene was detected in 17 isolates, 15 and two of which were of environmental and human origins, respectively. Gene hly was detected in 19 VC_NAG strains examined, two of which were isolated from humans and 17 from environments. The zot gene was not detected in any of the strains tested. Three VC_NAG strains of environmental origin were confirmed to produce NDM-1 and the blaNDM-1 gene was detected in those strains by PCR. Of note, one of the three NDM-1-producing VC_NAG strains was confirmed to carry ctxA, st and hly genes concurrently. This is the first report of isolation of NDM-1-producing VC_NAG strains in Vietnam. © 2015 The Societies and Wiley Publishing Asia Pty Ltd.

  8. New Carbenicillin-Hydrolyzing β-Lactamase (CARB-7) from Vibrio cholerae Non-O1, Non-O139 Strains Encoded by the VCR Region of the V. cholerae Genome†

    Science.gov (United States)

    Melano, Roberto; Petroni, Alejandro; Garutti, Alicia; Saka, Héctor Alex; Mange, Laura; Pasterán, Fernando; Rapoport, Melina; Rossi, Alicia; Galas, Marcelo

    2002-01-01

    In a previous study, an analysis of 77 ampicillin-nonsusceptible (resistant plus intermediate categories) strains of Vibrio cholerae non-O1, non-O139, isolated from aquatic environment and diarrheal stool, showed that all of them produced a β-lactamase with a pI of 5.4. Hybridization or amplification by PCR with a probe for blaTEM or primers for blaCARB gene families was negative. In this work, an environmental ampicillin-resistant strain from this sample, ME11762, isolated from a waterway in the west region of Argentina, was studied. The nucleotide sequence of the structural gene of the β-lactamase was determined by bidirectional sequencing of a Sau3AI fragment belonging to this isolate. The gene encodes a new 288-amino-acid protein, designated CARB-7, that shares 88.5% homology with the CARB-6 enzyme; an overall 83.2% homology with PSE-4, PSE-1, CARB-3, and the Proteus mirabilis N29 enzymes; and 79% homology with CARB-4 enzyme. The gene for this β-lactamase could not be transferred to Escherichia coli by conjugation. The nucleotide sequence of the flanking regions of the blaCARB-7 gene showed the occurrence of three 123-bp V. cholerae repeated sequences, all of which were found outside the predicted open reading frame. The upstream fragment of the blaCARB-7 gene shared 93% identity with a locus situated inside V. cholerae's chromosome 2. These results strongly suggest the chromosomal location of the blaCARB-7 gene, making this the first communication of a β-lactamase gene located on the VCR island of the V. cholerae genome. PMID:12069969

  9. A case of non-O1/non-O139 Vibrio cholerae septicemia and meningitis in a neonate

    Directory of Open Access Journals (Sweden)

    Yingying Hao

    2015-06-01

    Full Text Available A case of septicemia with meningitis due to non-O1/non-O139 Vibrio cholerae in a neonate is reported. The genotype and phenotype of the isolate were examined in relation to the major virulence genes. The isolate was shown to be non-toxin but cytotoxin-producing, distinguished from the dominant clone of non-O1/non-O139 V. cholerae by multilocus sequence typing.

  10. Population Structure and Evolution of Non-O1/Non-O139 Vibrio cholerae by Multilocus Sequence Typing

    Science.gov (United States)

    Lam, Connie; Leung, Queenie; Ahsan, Sunjukta; Reeves, Peter R.; Nair, G. Balakrish; Lan, Ruiting

    2013-01-01

    Pathogenic non-O1/non-O139 Vibrio cholerae strains can cause sporadic outbreaks of cholera worldwide. In this study, multilocus sequence typing (MLST) of seven housekeeping genes was applied to 55 non-O1/non-O139 isolates from clinical and environmental sources. Data from five published O1 isolates and 17 genomes were also included, giving a total of 77 isolates available for analysis. There were 66 sequence types (STs), with the majority being unique, and only three clonal complexes. The V. cholerae strains can be divided into four subpopulations with evidence of recombination among the subpopulations. Subpopulations I and III contained predominantly clinical strains. PCR screening for virulence factors including Vibrio pathogenicity island (VPI), cholera toxin prophage (CTXΦ), type III secretion system (T3SS), and enterotoxin genes (rtxA and sto/stn) showed that combinations of these factors were present in the clinical isolates with 85.7% having rtxA, 51.4% T3SS, 31.4% VPI, 31.4% sto/stn (NAG-ST) and 11.4% CTXΦ. These factors were also present in environmental isolates but at a lower frequency. Five strains previously mis-identified as V. cholerae serogroups O114 to O117 were also analysed and formed a separate population with V. mimicus. The MLST scheme developed in this study provides a framework to identify sporadic cholera isolates by genetic identity. PMID:23776471

  11. Population structure and evolution of non-O1/non-O139 Vibrio cholerae by multilocus sequence typing.

    Directory of Open Access Journals (Sweden)

    Sophie Octavia

    Full Text Available Pathogenic non-O1/non-O139 Vibrio cholerae strains can cause sporadic outbreaks of cholera worldwide. In this study, multilocus sequence typing (MLST of seven housekeeping genes was applied to 55 non-O1/non-O139 isolates from clinical and environmental sources. Data from five published O1 isolates and 17 genomes were also included, giving a total of 77 isolates available for analysis. There were 66 sequence types (STs, with the majority being unique, and only three clonal complexes. The V. cholerae strains can be divided into four subpopulations with evidence of recombination among the subpopulations. Subpopulations I and III contained predominantly clinical strains. PCR screening for virulence factors including Vibrio pathogenicity island (VPI, cholera toxin prophage (CTXΦ, type III secretion system (T3SS, and enterotoxin genes (rtxA and sto/stn showed that combinations of these factors were present in the clinical isolates with 85.7% having rtxA, 51.4% T3SS, 31.4% VPI, 31.4% sto/stn (NAG-ST and 11.4% CTXΦ. These factors were also present in environmental isolates but at a lower frequency. Five strains previously mis-identified as V. cholerae serogroups O114 to O117 were also analysed and formed a separate population with V. mimicus. The MLST scheme developed in this study provides a framework to identify sporadic cholera isolates by genetic identity.

  12. [Antibiotic Susceptibility of Vibrio cholerae non O1/non O139 Serogroups Isolated from Environment in the Rostov Region].

    Science.gov (United States)

    Selyanskaya, N A; Trishina, A V; Verkina, L M; Arkhangelskaya, I V; Kruglikov, V D; Zlenko, Yu M

    2014-01-01

    Analysis of the antibioticograms of 22 strains of Vibrio cholerae non O1/non O139 serogroups (ctxA- tepA-) isolated from the environment in the Rostov Region in 2011 showed that all the cultures were susceptible to ciprofloxacin, aminoglycosides, ceftriaxone, trimetoprime/sulfamethoxazole and resistant to levomycetin and furazolidone. 32%, 18% and 9% of the isolates were resistant to tetracycline, rifampicin and nalidixic acid respectively. No strains of V. cholerae susceptible to all the tested antimicrobials were detected. 37% of the V. cholerae isolates was resistant to two antibacterials and the others showed multiple resistance and contained 3-6 r-determinants of antibiotic resistance. Since the antibiotic resistance genes in Vibrio cholerae non O1/non O139 serogroups are often located on mobile genetic elements (plasmids, interferons, SXT elements), many strains of such organisms, the same as the natural environment, could serve as reservoirs of antibiotic resistance. The presence of antibiotic resistance r-determinants in the investigated strains in various combinations, the antibiotic resistance variability in the isolates collected on the same territory within a relatively short period of time require monitoring of antibiotic susceptibility in them and the use of the antibiotic for the etiotropic therapy only in strict accordance with the antibioticogram of the culture isolated from the concrete patient.

  13. Isolation frequency and susceptibility pattern of non-O1 and non-O139 Vibrio cholerae in a tertiary health care laboratory, 1999-2012.

    Science.gov (United States)

    Irfan, S; Fasih, N; Ghanchi, N K; Khan, E

    2016-04-28

    In the past decade the importance of non-O1 and non-O139 strains of Vibrio cholerae has been highlighted globally. This study aimed to evaluate the frequency and antimicrobial susceptibility profile of non-O1 and non-O139 V. cholerae in Pakistan. Data of stool specimens yielding growth of non-O1 and non-O139 V. cholerae isolated at a national referral laboratory from 1999 to 2012 were retrospectively analysed and evaluated for resistance to ampicillin, tetracycline, chloramphenicol, co-trimoxazole and ofloxacin. A total of 95 800 stool samples submitted over 1999-2012 yielded 3668 strains of V. cholerae, of which 6% were non-O1 and non-O139 V. cholerae. A high isolation rate was found in the summer season, with a peak in the year 2003. Antimicrobial susceptibility data revealed increasing resistance to co-trimoxazole and ampicillin, but strains remained highly susceptible to ofloxacin. Active surveillance of serotypes and antimicrobial susceptibility is essential to predict future epidemics and define measures to curtail the disease.

  14. Non-O1, non-O139 Vibrio cholerae bacteraemia: case report and literature review.

    Science.gov (United States)

    Deshayes, S; Daurel, C; Cattoir, V; Parienti, J-J; Quilici, M-L; de La Blanchardière, A

    2015-01-01

    Non-O1, non-O139 Vibrio cholerae (NOVC) are increasingly frequently observed ubiquitous microorganisms occasionally responsible for intestinal and extra-intestinal infections. Most cases involve self-limiting gastroenteritis or ear and wound infections in immunocompetent patients. Bacteraemia, which have been described in patients with predisposing factors, are rare and poorly known, both on the clinical and therapeutic aspects. We describe a case of NOVC bacteraemia and a systematic literature review in PubMed conducted up to November 2014 using a combination of the following search terms: "Vibrio cholerae non-O1" and "bacter(a)emia". The case was a 70 year-old healthy male subject returning from Senegal and suffering from NOVC bacteraemia associated with liver abscesses. Disease evolution was favourable after 2 months' therapy (ceftriaxone then ciprofloxacin). Three hundred and fifty cases of NOVC bacteraemia have been identified in the literature. The majority of patients were male (77 %), with a median age of 56 years and presenting with predisposing conditions (96 %), such as cirrhosis (55 %) or malignant disease (20 %). Diarrhoea was inconstant (42 %). Mortality was 33 %. The source of infection, identified in only 25 % of cases, was seafood consumption (54 %) or contaminated water (30 %). Practitioners should be aware of these infections, in order to warn patients with predisposing conditions, on the risk of ingesting raw or undercooked seafood or bathing in potentially infected waters.

  15. A case of non-O1/non-O139 Vibrio cholerae septicemia and meningitis in a neonate.

    Science.gov (United States)

    Hao, Yingying; Wang, Yueling; Bi, Zhenwang; Sun, Baixiu; Jin, Yan; Bai, Yuanyuan; Chen, Baoli; Shao, Chunhong; Sun, Xuerong; Lu, Zhiming

    2015-06-01

    A case of septicemia with meningitis due to non-O1/non-O139 Vibrio cholerae in a neonate is reported. The genotype and phenotype of the isolate were examined in relation to the major virulence genes. The isolate was shown to be non-toxin but cytotoxin-producing, distinguished from the dominant clone of non-O1/non-O139V. cholerae by multilocus sequence typing. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  16. Scanning the landscape of genome architecture of non-O1 and non-O139 Vibrio cholerae by whole genome mapping reveals extensive population genetic diversity.

    Directory of Open Access Journals (Sweden)

    Carol Chapman

    Full Text Available Historically, cholera outbreaks have been linked to V. cholerae O1 serogroup strains or its derivatives of the O37 and O139 serogroups. A genomic study on the 2010 Haiti cholera outbreak strains highlighted the putative role of non O1/non-O139 V. cholerae in causing cholera and the lack of genomic sequences of such strains from around the world. Here we address these gaps by scanning a global collection of V. cholerae strains as a first step towards understanding the population genetic diversity and epidemic potential of non O1/non-O139 strains. Whole Genome Mapping (Optical Mapping based bar coding produces a high resolution, ordered restriction map, depicting a complete view of the unique chromosomal architecture of an organism. To assess the genomic diversity of non-O1/non-O139 V. cholerae, we applied a Whole Genome Mapping strategy on a well-defined and geographically and temporally diverse strain collection, the Sakazaki serogroup type strains. Whole Genome Map data on 91 of the 206 serogroup type strains support the hypothesis that V. cholerae has an unprecedented genetic and genomic structural diversity. Interestingly, we discovered chromosomal fusions in two unusual strains that possess a single chromosome instead of the two chromosomes usually found in V. cholerae. We also found pervasive chromosomal rearrangements such as duplications and indels in many strains. The majority of Vibrio genome sequences currently in public databases are unfinished draft sequences. The Whole Genome Mapping approach presented here enables rapid screening of large strain collections to capture genomic complexities that would not have been otherwise revealed by unfinished draft genome sequencing and thus aids in assembling and finishing draft sequences of complex genomes. Furthermore, Whole Genome Mapping allows for prediction of novel V. cholerae non-O1/non-O139 strains that may have the potential to cause future cholera outbreaks.

  17. Scanning the landscape of genome architecture of non-O1 and non-O139 Vibrio cholerae by whole genome mapping reveals extensive population genetic diversity.

    Science.gov (United States)

    Chapman, Carol; Henry, Matthew; Bishop-Lilly, Kimberly A; Awosika, Joy; Briska, Adam; Ptashkin, Ryan N; Wagner, Trevor; Rajanna, Chythanya; Tsang, Hsinyi; Johnson, Shannon L; Mokashi, Vishwesh P; Chain, Patrick S G; Sozhamannan, Shanmuga

    2015-01-01

    Historically, cholera outbreaks have been linked to V. cholerae O1 serogroup strains or its derivatives of the O37 and O139 serogroups. A genomic study on the 2010 Haiti cholera outbreak strains highlighted the putative role of non O1/non-O139 V. cholerae in causing cholera and the lack of genomic sequences of such strains from around the world. Here we address these gaps by scanning a global collection of V. cholerae strains as a first step towards understanding the population genetic diversity and epidemic potential of non O1/non-O139 strains. Whole Genome Mapping (Optical Mapping) based bar coding produces a high resolution, ordered restriction map, depicting a complete view of the unique chromosomal architecture of an organism. To assess the genomic diversity of non-O1/non-O139 V. cholerae, we applied a Whole Genome Mapping strategy on a well-defined and geographically and temporally diverse strain collection, the Sakazaki serogroup type strains. Whole Genome Map data on 91 of the 206 serogroup type strains support the hypothesis that V. cholerae has an unprecedented genetic and genomic structural diversity. Interestingly, we discovered chromosomal fusions in two unusual strains that possess a single chromosome instead of the two chromosomes usually found in V. cholerae. We also found pervasive chromosomal rearrangements such as duplications and indels in many strains. The majority of Vibrio genome sequences currently in public databases are unfinished draft sequences. The Whole Genome Mapping approach presented here enables rapid screening of large strain collections to capture genomic complexities that would not have been otherwise revealed by unfinished draft genome sequencing and thus aids in assembling and finishing draft sequences of complex genomes. Furthermore, Whole Genome Mapping allows for prediction of novel V. cholerae non-O1/non-O139 strains that may have the potential to cause future cholera outbreaks.

  18. Genetic and phenotypic analysis of Vibrio cholerae non-O1, non-O139 isolated from German and Austrian patients.

    Science.gov (United States)

    Schirmeister, F; Dieckmann, R; Bechlars, S; Bier, N; Faruque, S M; Strauch, E

    2014-05-01

    Vibrio cholerae belonging to the non-O1, non-O139 serogroups are present in the coastal waters of Germany and in some German and Austrian lakes. These bacteria can cause gastroenteritis and extraintestinal infections, and are transmitted through contaminated food and water. However, non-O1, non-O139 V. cholerae infections are rare in Germany. We studied 18 strains from German and Austrian patients with diarrhea or local infections for their virulence-associated genotype and phenotype to assess their potential for infectivity in anticipation of possible climatic changes that could enhance the transmission of these pathogens. The strains were examined for the presence of genes encoding cholera toxin and toxin-coregulated pilus (TCP), as well as other virulence-associated factors or markers, including hemolysins, repeats-in-toxin (RTX) toxins, Vibrio seventh pandemic islands VSP-1 and VSP-2, and the type III secretion system (TTSS). Phenotypic assays for hemolysin activity, serum resistance, and biofilm formation were also performed. A dendrogram generated by incorporating the results of these analyses revealed genetic differences of the strains correlating with their clinical origin. Non-O1, non-O139 strains from diarrheal patients possessed the TTSS and/or the multifunctional autoprocessing repeats-in-toxin (MARTX) toxin, which were not found in the strains from ear or wound infections. Routine matrix-assisted laser desorption/ionization (MALDI-TOF) mass spectrometry (MS) analysis of all strains provided reliable identification of the species but failed to differentiate between strains or clusters. The results of this study indicate the need for continued surveillance of V. cholerae non-O1, non-O139 in Germany, in view of the predicted increase in the prevalence of Vibrio spp. due to the rise in surface water temperatures.

  19. Prevalence and molecular characterization of Vibrio cholerae O1, non-O1 and non-O139 in tropical seafood in Cochin, India.

    Science.gov (United States)

    Kumar, Rakesh; Lalitha, Kuttannappilly V

    2013-03-01

    The objective of this study was to determine the prevalence of O1, O139, and non-O1 and non-O139 Vibrio cholerae, which were associated with fresh and raw seafood samples harvested from Cochin, India waters during 2009-2011. Results from V. cholerae-specific biochemical, molecular, and serological assays identified five El Tor V. cholerae O1 Ogawa strains and 377 non-O1, non-O139 V. cholerae strains from 265 seafood samples. V. cholerae O139 strains were not isolated. Polymerase chain reaction assays confirmed the presence of V. cholerae O1 El Tor biotype in seafood. Antibiotic susceptibility analysis revealed that the V. cholerae O1 strains were pansusceptible to 20 test antibiotics, whereas 26%, 40%, 62%, and 84% of the non-O1, non-O139 V. cholerae strains were resistant to cefpodoxime, ticarcillin, augmentin, and colistin, respectively. Detection of virulence and regulatory genes in V. cholerae associated with seafood revealed the presence of virulence and regulatory genes (i.e., ctx, zot, ace, toxR genes) in V. cholerae O1 strains, nevertheless, presence of ace and toxR genes were detected in non-O1, non-O139 in 9.8 and 91% strains, respectively. In conclusion, the presence of pathogenic V. cholerae in seafood harvested from local Cochin waters warrants the introduction of a postharvest seafood monitoring program, which will lead to a greater understanding of the distribution, abundance, and virulence of diverse pathogenic Vibrio populations that inhabit these different coastal regions so that a risk management program can be established.

  20. Toxin(s), Other Than Cholera Toxin, Produced by Environmental Non O1 Non O139 Vibrio cholerae

    Institute of Scientific and Technical Information of China (English)

    Kohinur Begum; Chowdhury R. Ahsan; Mohammad Ansaruzzaman; Dilip K. Dutta; Qazi S.Ahmad; Kaisar A. Talukder

    2006-01-01

    A total of 39 Vibrio cholerae non O1 non O139 strains were isolated from surface waters of different parts of Dhaka City, Bangladesh. All these strains showed lack of ctx or zot gene, as demonstrated by the PCR analysis.Eighteen representative strains were tested for enterotoxin production using a rabbit ileal loop model, of which live cells of 8 strains and culture filtrates of 6 strains produced fluid accumulation in ileal loops. However, none of them produced heat stable toxin (ST), as detected by suckling mouse assay. On the other hand, 15% of isolates produced cytotoxin as detected by the Chinese Hamster Ovary (CHO) cell assay. Fifty times concentrated culture filtrates of the representative strains did not give any precipitin band against the anti-cholera toxin, suggesting the strains produced an enterotoxin, which is antigenically different from known cholera toxin (CT). Eighty percent of the total isolates were found to be positive for heat labile haemolysin detected by tube method, whereas, 39% were found positive by the Christie-Atkins-Munch-Petersen (CAMP) method. However, 87% of the isolates were positive for haemagglutinin/protease and all of the strains were positive for mannose-sensitive-haemagglutinin assay.

  1. Detection of ctx gene positive non-O1/non-O139 V. cholerae in shrimp aquaculture environments.

    Science.gov (United States)

    Madhusudana, Rao B; Surendran, P K

    2013-06-01

    Water and post-larvae samples from black tiger (Penaeus monodon) shrimp hatcheries; pond water, pond sediment and shrimp from aquaculture farms were screened for the presence of V. cholerae. A V. cholerae-duplex PCR method was developed by utilizing V. cholerae species specific sodB primers and ctxAB genes specific primers. Incidence of V. cholerae was not observed in shrimp hatchery samples but was noticed in aquaculture samples. The incidence of V. cholerae was higher in pond water (7.6%) than in pond sediment (5.2%). Shrimp head (3.6%) portion had relatively higher incidence than shrimp muscle (1.6%). All the V. cholerae isolates (n = 42) belonged to non-O1/non-O139 serogroup, of which 7% of the V. cholerae isolates were potentially cholera-toxigenic (ctx positive). All the ctx positive V. cholerae (n = 3) were isolated from the pond water. Since, cholera toxin (CT) is the major contributing factor for cholera gravis, it is proposed that the mere presence of non-O1/non-O139 V. cholerae need not be the biohazard criterion in cultured black tiger shrimp but only the presence of ctx carrying non-O1/non-O139 V. cholerae may be considered as potential public health risk.

  2. The first case of bacteraemia due to non-O1/non-O139 Vibrio cholerae in a type 2 diabetes mellitus patient in mainland China.

    Science.gov (United States)

    Lu, Binghuai; Zhou, Haijian; Li, Dong; Li, Fengjuan; Zhu, Fengxia; Cui, Yanchao; Huang, Lei; Wang, Duochun

    2014-08-01

    Bacteraemia due to non-O1/non-O139 Vibrio cholerae is rarely documented in mainland China. We report such a case in a 70-year-old male with type 2 diabetes mellitus. The clinical features, phenotypic analyses, and presence of a panel of known virulence genes in the isolated strain are described. To the best of our knowledge, this is the first reported case of bacteraemia due to this strain in a T2DM patient without other coexisting underlying diseases in mainland China.

  3. Necrotizing fasciitis due to Vibrio cholerae non-O1/non-O139 after exposure to Austrian bathing sites.

    Science.gov (United States)

    Hirk, Sonja; Huhulescu, Steliana; Allerberger, Franz; Lepuschitz, Sarah; Rehak, Sonja; Weil, Sandra; Gschwandtner, Elisabeth; Hermann, Michael; Neuhold, Stephanie; Zoufaly, Alexander; Indra, Alexander

    2016-02-01

    We report on two cases of necrotizing fasciitis of the lower leg due to nontoxigenic Vibrio cholerae (V. cholerae). A 73-year-old woman (case 1) and an 80-year-old man (case 2) were hospitalized with symptoms of necrotizing fasciitis on July 18 and August 15, 2015, respectively. In both cases, symptoms started the day after swimming in local ponds. Swabs gained intraoperatively and a blood culture from the male patient, yielded V. cholerae non-O1/non-O139, negative for cholera toxin gene ctx and positive for hemolysin genes hlyA and hlyB. Water samples taken from pond A on August 17, 2015 (32 days after exposure of case 1) and from pond B on August 20, 2015 (7 days after exposure of case 2) yielded non-O1/non-O139 V. cholerae in most-probable numbers of > 11,000 per 100 ml each. The occurrence of two cases of necrotizing fasciitis within a 1 month period related to two Austrian non-saline bathing waters, previously not known to harbor V. cholerae, is probably linked to the prevailing extreme weather conditions (heat wave, drought) this summer in Austria. While case 1 was discharged in good clinical condition after 73 days, case 2 died after four months of hospitalization. Public health authorities are challenged to assess the effects of long-term climate change on pathogen growth and survival in continental bodies of fresh water.

  4. Cholera outbreaks in Nigeria are associated with multidrug resistant atypical El Tor and non-O1/non-O139 Vibrio cholerae.

    Science.gov (United States)

    Marin, Michel A; Thompson, Cristiane C; Freitas, Fernanda S; Fonseca, Erica L; Aboderin, A Oladipo; Zailani, Sambo B; Quartey, Naa Kwarley E; Okeke, Iruka N; Vicente, Ana Carolina P

    2013-01-01

    The current millennium has seen a steep rise in the number, size and case-fatalities of cholera outbreaks in many African countries. Over 40,000 cases of cholera were reported from Nigeria in 2010. Variants of Vibrio cholerae O1 El Tor biotype have emerged but very little is known about strains causing cholera outbreaks in West Africa, which is crucial for the implementation of interventions to control epidemic cholera. V. cholerae isolates from outbreaks of acute watery diarrhea in Nigeria from December, 2009 to October, 2010 were identified by standard culture methods. Fifteen O1 and five non-O1/non-O139 strains were analyzed; PCR and sequencing targeted regions associated with virulence, resistance and biotype were performed. We also studied genetic interrelatedness among the strains by multilocus sequence analysis and pulsed-field gel electrophoresis. The antibiotic susceptibility was tested by the disk diffusion method and E-test. We found that multidrug resistant atypical El Tor strains, with reduced susceptibility to ciprofloxacin and chloramphenicol, characterized by the presence of the SXT element, and gyrA(Ser83Ile)/parC(Ser85Leu) alleles as well CTX phage and TCP cluster characterized by rstR(ElTor), ctxB-7 and tcpA(CIRS) alleles, respectively, were largely responsible for cholera outbreaks in 2009 and 2010. We also identified and characterized a V. cholerae non-O1/non-O139 lineage from cholera-like diarrhea cases in Nigeria. The recent Nigeria outbreaks have been determined by multidrug resistant atypical El Tor and non-O1/non-O139 V. cholerae strains, and it seems that the typical El Tor, from the beginning of seventh cholera pandemic, is no longer epidemic/endemic in this country. This scenario is similar to the East Africa, Asia and Caribbean countries. The detection of a highly virulent, antimicrobial resistant lineage in Nigeria is worrisome and points to a need for vaccine-based control of the disease. This study has also revealed the putative

  5. Extraintestinal Infections Caused by Non-toxigenic Vibrio cholerae non-O1/non-O139.

    Science.gov (United States)

    Chowdhury, Goutam; Joshi, Sangeeta; Bhattacharya, Sanjay; Sekar, Uma; Birajdar, Balaji; Bhattacharyya, Arpita; Shinoda, Sumio; Ramamurthy, Thandavarayan

    2016-01-01

    Vibrio cholerae is an aerobic, sucrose fermentative Gram-negative bacterium that generally prevails in the environment. Pathogenic V. cholerae is well-known as causative agent of acute diarrhea. Apart from enteric infections, V. cholerae may also cause other diseases. However, their role in causing extraintestinal infections is not fully known as it needs proper identification and evaluation. Four cases of extraintestinal infections due to V. cholerae non-O1/non-O139 have been investigated. The isolates were screened for phenotypic and genetic characteristics with reference to their major virulence genes. Serologically distinct isolates harbored rtx, msh, and hly but lacked enteric toxin encoding genes that are generally present in toxigenic V. cholerae. Timely detection of this organism can prevent fatalities in hospital settings. The underlying virulence potential of V. cholerae needs appropriate testing and intervention.

  6. Non-O1/non-O139 Vibrio cholerae septicaemia in a Saudi man: a case report

    Science.gov (United States)

    El-Hossary, Dalia; Jiman-Fatani, Asif; Al-Ghamdi, Rahaf

    2017-01-01

    Background. The non-O1/non-O139 serogroups of Vibrio cholerae occur in diverse natural niches, and usually cause mild and self-limiting gastrointestinal illness. However, they have well-documented potential to cause invasive and extra-intestinal infections among immunocompromised patients. Furthermore, their ability to grow in low-salinity surface water, and the existence of asymptomatic human carriers, suggest novel acquisition routes for this unusual infection, even in people without obvious risk factors. Case presentation. A 62-year-old man presented with epigastric pain, vomiting and fever. The patient had a history of diabetes and cholecystectomy, although our initial examination did not reveal any significant findings that might indicate V. cholerae infection. However, blood cultures subsequently revealed the presence of V. cholerae, which was positively identified using both conventional and modern non-conventional technologies. The identity of the V. cholerae isolate was confirmed using Vitek MS (matrix–assisted laser desorption ionization-time of flight MS) and the FilmArray system, in addition to its initial identification using the Vitek 2 system. The septicaemia was successfully treated using a 14 day course of ciprofloxacin. Conclusion. The present case highlights the need to remain highly suspicious of non-O1/non-O139 V. cholerae infections in patients with known risk factors, as well as in healthy individuals with epidemiological exposure and compatible clinical symptoms. Special care should be taken to avoid false-positive results from confirmatory laboratory tests, as the organism can grow in fresh water, and the results should be verified using multiple methods. PMID:28348803

  7. Antimicrobial Susceptibility among Urban Wastewater and Wild Shellfish Isolates of Non-O1/Non-O139 Vibrio cholerae from La Rance Estuary (Brittany, France)

    Science.gov (United States)

    Baron, Sandrine; Larvor, Emeline; Chevalier, Séverine; Jouy, Eric; Kempf, Isabelle; Granier, Sophie A.; Lesne, Jean

    2017-01-01

    The early 2000s marked the end of the Golden age of the antibiotics and the beginning of the awareness on the potential threat to human health due to the dissemination of antimicrobial resistance. As a base-line study, we investigated the antimicrobial susceptibility of 99 strains of non-O1/non-O139 Vibrio cholerae isolated from wastewater and shellfish in 2000/2001 within La Rance estuary (Brittany, France). All isolates were susceptible to amoxicillin-clavulanic acid, cefotaxime, imipenem, chloramphenicol, nalidixic acid, ciprofloxacin, norfloxacin, amikacin, gentamicin, tetracycline, doxycycline, trimethoprim-sulfamethoxazole, and erythromycin. The only resistances were to streptomycin, sulfonamides and ampicillin: 54.6% of the isolates had acquired resistance to at least one antimicrobial agent among them and only six isolates from cockles were multidrug resistant. On the basis of the distribution of a limited selection of resistance associated genes, our study shows that V. cholerae can constitute an environmental reservoir for these genes. However, none of our isolates harbored integron. This result casts doubt on the capacity of non-O1/non-O139 V. cholerae to acquire resistance-associated genes in such context, and on its potential role of indicator of the dissemination of antimicrobial resistance in the aquatic environment.

  8. Antimicrobial Susceptibility among Urban Wastewater and Wild Shellfish Isolates of Non-O1/Non-O139 Vibrio cholerae from La Rance Estuary (Brittany, France

    Directory of Open Access Journals (Sweden)

    Sandrine Baron

    2017-09-01

    Full Text Available The early 2000s marked the end of the Golden age of the antibiotics and the beginning of the awareness on the potential threat to human health due to the dissemination of antimicrobial resistance. As a base-line study, we investigated the antimicrobial susceptibility of 99 strains of non-O1/non-O139 Vibrio cholerae isolated from wastewater and shellfish in 2000/2001 within La Rance estuary (Brittany, France. All isolates were susceptible to amoxicillin-clavulanic acid, cefotaxime, imipenem, chloramphenicol, nalidixic acid, ciprofloxacin, norfloxacin, amikacin, gentamicin, tetracycline, doxycycline, trimethoprim-sulfamethoxazole, and erythromycin. The only resistances were to streptomycin, sulfonamides and ampicillin: 54.6% of the isolates had acquired resistance to at least one antimicrobial agent among them and only six isolates from cockles were multidrug resistant. On the basis of the distribution of a limited selection of resistance associated genes, our study shows that V. cholerae can constitute an environmental reservoir for these genes. However, none of our isolates harbored integron. This result casts doubt on the capacity of non-O1/non-O139 V. cholerae to acquire resistance-associated genes in such context, and on its potential role of indicator of the dissemination of antimicrobial resistance in the aquatic environment.

  9. GENOTYPE AND DRUG RESISTANCE OF CLINICAL AND ENVIRONMENTAL VIBRIO CHOLERAE NON-O1/NON-O139 IN NORTHEASTERN THAILAND.

    Science.gov (United States)

    Chomvarin, Chariya; Jumroenjit, Warin; Tangkanakul, Waraluk; Hasan, Nur A; Chaicumpar, Kunyaluk; Faksri, Kiatichai; Huq, Anwar

    2014-11-01

    A total of 124 V cholerae non-O1/non-O139 isolates were collected in Khon Kaen, Thailand from diarrheal patients, asymptomatic carriers and environmental water. The presence of virulence-associated and regulatory genes including ctxA, tcpA, zot, ace, ompU, stn, hlyA and toxR) were examined using multiplex PCR. The genomic diversity of the various V. cholerae isolates were differentiated using the random amplified polymorphic DNA (RAPD) method. Antimicrobial susceptibility was tested using disk diffusion. All of V. cholerae non-O/non-O139 isolates carried hlyA and toxR and none carried ctxA and tcpA. The zot, ace and both genes together were found in 1.6%, 4.7% and 4.7% of 64 clinical V. cholerae non-O1 isolates, respectively, while the environmental ones did not. The stn gene was found in 3.1% (2/64) of the clinical and 3.3% (2/60) of the environmental isolates. The RAPD patterns were differentiated into 45 types (A to 2S). RAPD type A (32.3%) was the most frequently found in both clinical and environmental V cholerae non-O1 strains (34.4% and 30.0%, respectively); indicating that there was a clonal relationship between some clinical and environmental isolates whereas almost all of the environmental isolates belonged to different clones. All strains were sensitive to ciprofloxacin and norfloxacin. The environmental isolates (30%) were more resistant than the clinical ones (21.9%). Resistance to sulfamethoxazole/trimethoprim and tetracycline among the clinical isolates occurred in 9.4% (6/64) in 2007, during which period the prevalence of V cholerae O1 increased. We conclude that V. cholerae non-O1/non-O139 from the aquatic environment are potentially pathogenic and this same aquatic environment may be a source of antimicrobial resistance in V. cholerae.

  10. Non-O1/Non-O139 Vibrio cholerae Carrying Multiple Virulence Factors and V. cholerae O1 in the Chesapeake Bay, Maryland

    Science.gov (United States)

    Ceccarelli, Daniela; Chen, Arlene; Hasan, Nur A.; Rashed, Shah M.; Huq, Anwar

    2015-01-01

    Non-O1/non-O139 Vibrio cholerae inhabits estuarine and coastal waters globally, but its clinical significance has not been sufficiently investigated, despite the fact that it has been associated with septicemia and gastroenteritis. The emergence of virulent non-O1/non-O139 V. cholerae is consistent with the recognition of new pathogenic variants worldwide. Oyster, sediment, and water samples were collected during a vibrio surveillance program carried out from 2009 to 2012 in the Chesapeake Bay, Maryland. V. cholerae O1 was detected by a direct fluorescent-antibody (DFA) assay but was not successfully cultured, whereas 395 isolates of non-O1/non-O139 V. cholerae were confirmed by multiplex PCR and serology. Only a few of the non-O1/non-O139 V. cholerae isolates were resistant to ampicillin and/or penicillin. Most of the isolates were sensitive to all antibiotics tested, and 77 to 90% carried the El Tor variant hemolysin gene hlyAET, the actin cross-linking repeats in toxin gene rtxA, the hemagglutinin protease gene hap, and the type 6 secretion system. About 19 to 21% of the isolates carried the neuraminidase-encoding gene nanH and/or the heat-stable toxin (NAG-ST), and only 5% contained a type 3 secretion system. None of the non-O1/non-O139 V. cholerae isolates contained Vibrio pathogenicity island-associated genes. However, ctxA, ace, or zot was present in nine isolates. Fifty-five different genotypes showed up to 12 virulence factors, independent of the source of isolation, and represent the first report of both antibiotic susceptibility and virulence associated with non-O1/non-O139 V. cholerae from the Chesapeake Bay. Since these results confirm the presence of potentially pathogenic non-O1/non-O139 V. cholerae, monitoring for total V. cholerae, regardless of serotype, should be done within the context of public health. PMID:25556194

  11. Non-O1/non-O139 Vibrio cholerae carrying multiple virulence factors and V. cholerae O1 in the Chesapeake Bay, Maryland.

    Science.gov (United States)

    Ceccarelli, Daniela; Chen, Arlene; Hasan, Nur A; Rashed, Shah M; Huq, Anwar; Colwell, Rita R

    2015-03-01

    Non-O1/non-O139 Vibrio cholerae inhabits estuarine and coastal waters globally, but its clinical significance has not been sufficiently investigated, despite the fact that it has been associated with septicemia and gastroenteritis. The emergence of virulent non-O1/non-O139 V. cholerae is consistent with the recognition of new pathogenic variants worldwide. Oyster, sediment, and water samples were collected during a vibrio surveillance program carried out from 2009 to 2012 in the Chesapeake Bay, Maryland. V. cholerae O1 was detected by a direct fluorescent-antibody (DFA) assay but was not successfully cultured, whereas 395 isolates of non-O1/non-O139 V. cholerae were confirmed by multiplex PCR and serology. Only a few of the non-O1/non-O139 V. cholerae isolates were resistant to ampicillin and/or penicillin. Most of the isolates were sensitive to all antibiotics tested, and 77 to 90% carried the El Tor variant hemolysin gene hlyAET, the actin cross-linking repeats in toxin gene rtxA, the hemagglutinin protease gene hap, and the type 6 secretion system. About 19 to 21% of the isolates carried the neuraminidase-encoding gene nanH and/or the heat-stable toxin (NAG-ST), and only 5% contained a type 3 secretion system. None of the non-O1/non-O139 V. cholerae isolates contained Vibrio pathogenicity island-associated genes. However, ctxA, ace, or zot was present in nine isolates. Fifty-five different genotypes showed up to 12 virulence factors, independent of the source of isolation, and represent the first report of both antibiotic susceptibility and virulence associated with non-O1/non-O139 V. cholerae from the Chesapeake Bay. Since these results confirm the presence of potentially pathogenic non-O1/non-O139 V. cholerae, monitoring for total V. cholerae, regardless of serotype, should be done within the context of public health. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  12. Non-O1/Non-O139 Vibrio cholerae Avian Isolate from France Cocarrying the bla(VIM-1) and bla(VIM-4) Genes.

    Science.gov (United States)

    Aberkane, Salim; Compain, Fabrice; Barraud, Olivier; Ouédraogo, Abdoul-Salam; Bouzinbi, Nicolas; Vittecoq, Marion; Jean-Pierre, Hélène; Decré, Dominique; Godreuil, Sylvain

    2015-10-01

    We describe here a non-O1/non-O139 Vibrio cholerae isolate producing both VIM-1 and VIM-4 carbapenemases. It was isolated from a yellow-legged gull in southern France. The blaVIM genes were part of a class 1 integron structure located in an IncA/C plasmid. This study emphasizes the presence of carbapenemase genes in wildlife microbiota.

  13. Vibriosis, not cholera: toxigenic Vibrio cholerae non-O1, non-O139 infections in the United States, 1984-2014.

    Science.gov (United States)

    Crowe, S J; Newton, A E; Gould, L H; Parsons, M B; Stroika, S; Bopp, C A; Freeman, M; Greene, K; Mahon, B E

    2016-11-01

    Toxigenic strains of Vibrio cholerae serogroups O1 and O139 have caused cholera epidemics, but other serogroups - such as O75 or O141 - can also produce cholera toxin and cause severe watery diarrhoea similar to cholera. We describe 31 years of surveillance for toxigenic non-O1, non-O139 infections in the United States and map these infections to the state where the exposure probably originated. While serogroups O75 and O141 are closely related pathogens, they differ in how and where they infect people. Oysters were the main vehicle for O75 infection. The vehicles for O141 infection include oysters, clams, and freshwater in lakes and rivers. The patients infected with serogroup O75 who had food traceback information available ate raw oysters from Florida. Patients infected with O141 ate oysters from Florida and clams from New Jersey, and those who only reported being exposed to freshwater were exposed in Arizona, Michigan, Missouri, and Texas. Improving the safety of oysters, specifically, should help prevent future illnesses from these toxigenic strains and similar pathogenic Vibrio species. Post-harvest processing of raw oysters, such as individual quick freezing, heat-cool pasteurization, and high hydrostatic pressurization, should be considered.

  14. Survey on antimicrobial resistance patterns in Vibrio vulnificus and Vibrio cholerae non-O1/non-O139 in Germany reveals carbapenemase-producing Vibrio cholerae in coastal waters.

    Science.gov (United States)

    Bier, Nadja; Schwartz, Keike; Guerra, Beatriz; Strauch, Eckhard

    2015-01-01

    An increase in the occurrence of potentially pathogenic Vibrio species is expected for waters in Northern Europe as a consequence of global warming. In this context, a higher incidence of Vibrio infections is predicted for the future and forecasts suggest that people visiting and living at the Baltic Sea are at particular risk. This study aimed to investigate antimicrobial resistance patterns among Vibrio vulnificus and Vibrio cholerae non-O1/non-O139 isolates that could pose a public health risk. Antimicrobial susceptibility of 141 V. vulnificus and 184 V. cholerae non-O1/non-O139 strains isolated from German coastal waters (Baltic Sea and North Sea) as well as from patients and retail seafood was assessed by broth microdilution and disk diffusion. Both species were susceptible to most of the agents tested (12 subclasses) and no multidrug-resistance was observed. Among V. vulnificus isolates, non-susceptibility was exclusively found toward aminoglycosides. In case of V. cholerae, a noticeable proportion of strains was non-susceptible to aminopenicillins and aminoglycosides. In addition, resistance toward carbapenems, quinolones, and folate pathway inhibitors was sporadically observed. Biochemical testing indicated the production of carbapenemases with unusual substrate specificity in four environmental V. cholerae strains. Most antimicrobial agents recommended for treatment of V. vulnificus and V. cholerae non-O1/non-O139 infections were found to be effective in vitro. However, the occurrence of putative carbapenemase producing V. cholerae in German coastal waters is of concern and highlights the need for systematic monitoring of antimicrobial susceptibility in potentially pathogenic Vibrio spp. in Europe.

  15. O Serogroup-Specific Touchdown-Multiplex Polymerase Chain Reaction for Detection and Identification of Vibrio cholerae O1, O139, and Non-O1/Non-O139

    Directory of Open Access Journals (Sweden)

    Adisak Bhumiratana

    2014-01-01

    Full Text Available A novel, sensitive locus-specific touchdown-multiplex polymerase chain reaction (TMPCR, which is based on two-stage amplification pertaining to multiplex PCR and conditional touchdown strategy, was used in detecting and differentiating Vibrio cholerae serogroups. A panel of molecular marker-based TMPCR method generates reproducible profiles of V. cholerae-specific (588 bp amplicons derived from ompW gene encoding the outer membrane protein and serogroup-specific amplicons, 364 bp for the O1 and 256 bp for the O139, authentically copied from rfb genes responsible for the lipopolysaccharide biosynthesis. The TMPCR amplification efficiency yields either equally or unequally detectable duplex DNA bands of the O1 (588 and 364 bp and O139 (588 and 256 bp or a DNA fragment of non-O1/non-O139 (588 bp while providing no false positive identifications using the genomic DNA templates of the other vibrios and Enterobacteriaceae. The reciprocal analysis of two-template combinations demonstrated that, using V. cholerae O1, O139, or equally mixed O1 and O139, the TMPCR had a detection limit of as low as 100 pg of the O1, O139, or non-O1/non-O139 in reactions containing unequally or equally mixed gDNAs. In addition, the O serogroup-specific TMPCR method had 100% agreement with the serotyping method when examined for the serotyped V. cholerae reference strains and those recovered from clinical samples. The potential benefit of using this TMPCR tool would augment the serotyping method used in epidemiological surveillance and monitoring of V. cholerae serogroups, O1, O139, and non-O1/non-O139 present in clinical and environmental samples.

  16. Distribution of virulence markers in clinical and environmental Vibrio cholerae non-O1/non-O139 strains isolated in Brazil from 1991 to 2000 Distribuição dos marcadores de virulência em cepas clínicas e ambientais de Vibrio cholerae não O1/não O139, isoladas no Brasil no período de 1991 a 2000

    Directory of Open Access Journals (Sweden)

    Grace Nazareth Diogo Theophilo

    2006-04-01

    Full Text Available One hundred seventy nine Vibrio cholerae non-O1/non-O139 strains from clinical and different environmental sources isolated in Brazil from 1991 to 2000 were serogrouped and screened for the presence of four different virulence factors. The Random Amplification of Polymorphic DNA (RAPD technique was used to evaluate the genetic relatedness among strains. Fifty-four different serogroups were identified and V. cholerae O26 was the most common (7.8%. PCR analysis for three genes (ctxA, zot, ace located of the CTX genetic element and one gene (tcpA located on the VPI pathogenicity island showed that 27 strains harbored one or more of these genes. Eight (4.5% strains possessed the complete set of CTX element genes and all but one of these belonged to the O26 serogroup suggesting that V. cholerae O26 has the potential to be an epidemic strain. The RAPD profiles revealed a wide variability among strains and no genetic correlation was observed.Cento e setenta e nove amostras de V. cholerae não O1/não O139, isoladas de casos clínicos (139 e de meio ambiente (40, no período de 1991 a 2000 no Brasil, foram caracterizadas antigenicamente pelo National Institute of Health (Japão e investigadas quanto ao seu potencial genético de virulência, representado pelos genes ctxA, zot, ace e tcpA. As análises fenotípicas revelaram extraordinária diversidade antigênica, com a ocorrência de 54 diferentes sorogrupos, com prevalência para O26 (7,8%. A técnica de PCR, empregada na detecção dos genes localizados no elemento genético CTX (ctxA, zot, ace e na Ilha de Patogenicidade de Vibrio-VPI (tcpA, possibilitou a identificação de 27 cepas contendo qualquer um desses genes. O gene ctxA (codificador da sub-unidade A de CT, só foi evidenciado no sorogrupo O26, sendo também o único capaz de se apresentar com o cassete de virulência de forma intacta. Com base nos resultados obtidos deste estudo preliminar, admite-se a hipótese da potencialidade destas

  17. IncA/C Conjugative Plasmids Mobilize a New Family of Multidrug Resistance Islands in Clinical Vibrio cholerae Non-O1/Non-O139 Isolates from Haiti

    Directory of Open Access Journals (Sweden)

    Nicolas Carraro

    2016-07-01

    Full Text Available Mobile genetic elements play a pivotal role in the adaptation of bacterial populations, allowing them to rapidly cope with hostile conditions, including the presence of antimicrobial compounds. IncA/C conjugative plasmids (ACPs are efficient vehicles for dissemination of multidrug resistance genes in a broad range of pathogenic species of Enterobacteriaceae. ACPs have sporadically been reported in Vibrio cholerae, the infectious agent of the diarrheal disease cholera. The regulatory network that controls ACP mobility ultimately depends on the transcriptional activation of multiple ACP-borne operons by the master activator AcaCD. Beyond ACP conjugation, AcaCD has also recently been shown to activate the expression of genes located in the Salmonella genomic island 1 (SGI1. Here, we describe MGIVchHai6, a novel and unrelated mobilizable genomic island (MGI integrated into the 3′ end of trmE in chromosome I of V. cholerae HC-36A1, a non-O1/non-O139 multidrug-resistant clinical isolate recovered from Haiti in 2010. MGIVchHai6 contains a mercury resistance transposon and an integron In104-like multidrug resistance element similar to the one of SGI1. We show that MGIVchHai6 excises from the chromosome in an AcaCD-dependent manner and is mobilized by ACPs. Acquisition of MGIVchHai6 confers resistance to β-lactams, sulfamethoxazole, tetracycline, chloramphenicol, trimethoprim, and streptomycin/spectinomycin. In silico analyses revealed that MGIVchHai6-like elements are carried by several environmental and clinical V. cholerae strains recovered from the Indian subcontinent, as well as from North and South America, including all non-O1/non-O139 clinical isolates from Haiti.

  18. Virulence factors of non-O1 non-O139 Vibrio cholerae isolated in Córdoba, Argentina Factores de virulencia de Vibrio cholerae no-O1 no-O139 aislados en Córdoba, Argentina

    Directory of Open Access Journals (Sweden)

    C. Bidinost

    2004-12-01

    Full Text Available V. cholerae non-O1 non-O139 serogroups isolated from clinical and environmental sources in Córdoba, Argentina, were analyzed for the presence and expression of virulence genes. Most of the strains studied contained the genes toxR and hlyA, but lacked ctxA, zot, ace, tcpA and stn. The culture supernatants were tested for hemolytic and cytotoxic activity. The enterotoxic potential of the strains was studied in a rabbit ileal loop assay and their genetic profiles were compared by PFGE. The environmental strains varied in their virulence phenotype and showed no-clonal relationships. The clinical strains were highly enterotoxic, hemolytic, proteolytic and showed indistinguishable PFGE profiles, although they differed in their cytotoxic activity. This is the first description, using cell culture and “in vivo” studies, of the virulence properties of non-O1 non-O139 V. cholerae from Argentina.En este trabajo se analizó la presencia y expresión de genes de virulencia en V. cholerae no-O1 no-O139 de origen clínico y ambiental, aislados en Córdoba, Argentina. La mayoría de las cepas estudiadas contiene los genes toxR y hlyA, pero no ctxA, zot, ace, tcpA y stn. Se analizó la actividad hemolítica y citotóxica de estas cepas en los sobrenadantes de cultivo, así como su potencial enterotóxico en ensayos de asa ileal ligada de conejo. Además, los aislamientos fueron comparados por sus perfiles genéticos en PFGE. Las cepas del medio ambiente mostraron variación en su fenotipo de virulencia y no mostraron relación clonal. Las cepas clínicas fueron muy enterotóxicas, hemolíticas, proteolíticas y mostraron perfiles indistinguibles de PFGE, aunque mostraron diferencias en su actividad citotóxica. En este trabajo se describen por primera vez, utilizando ensayos de cultivo celular e “in vivo”, propiedades de virulencia de V. cholerae no-O1 no-O139 aislados en Argentina.

  19. IncA/C Conjugative Plasmids Mobilize a New Family of Multidrug Resistance Islands in Clinical Vibrio cholerae Non-O1/Non-O139 Isolates from Haiti.

    Science.gov (United States)

    Carraro, Nicolas; Rivard, Nicolas; Ceccarelli, Daniela; Colwell, Rita R; Burrus, Vincent

    2016-07-19

    Mobile genetic elements play a pivotal role in the adaptation of bacterial populations, allowing them to rapidly cope with hostile conditions, including the presence of antimicrobial compounds. IncA/C conjugative plasmids (ACPs) are efficient vehicles for dissemination of multidrug resistance genes in a broad range of pathogenic species of Enterobacteriaceae ACPs have sporadically been reported in Vibrio cholerae, the infectious agent of the diarrheal disease cholera. The regulatory network that controls ACP mobility ultimately depends on the transcriptional activation of multiple ACP-borne operons by the master activator AcaCD. Beyond ACP conjugation, AcaCD has also recently been shown to activate the expression of genes located in the Salmonella genomic island 1 (SGI1). Here, we describe MGIVchHai6, a novel and unrelated mobilizable genomic island (MGI) integrated into the 3' end of trmE in chromosome I of V. cholerae HC-36A1, a non-O1/non-O139 multidrug-resistant clinical isolate recovered from Haiti in 2010. MGIVchHai6 contains a mercury resistance transposon and an integron In104-like multidrug resistance element similar to the one of SGI1. We show that MGIVchHai6 excises from the chromosome in an AcaCD-dependent manner and is mobilized by ACPs. Acquisition of MGIVchHai6 confers resistance to β-lactams, sulfamethoxazole, tetracycline, chloramphenicol, trimethoprim, and streptomycin/spectinomycin. In silico analyses revealed that MGIVchHai6-like elements are carried by several environmental and clinical V. cholerae strains recovered from the Indian subcontinent, as well as from North and South America, including all non-O1/non-O139 clinical isolates from Haiti. Vibrio cholerae, the causative agent of cholera, remains a global public health threat. Seventh-pandemic V. cholerae acquired multidrug resistance genes primarily through circulation of SXT/R391 integrative and conjugative elements. IncA/C conjugative plasmids have sporadically been reported to

  20. Survey on antimicrobial resistance patterns in Vibrio vulnificus and Vibrio cholerae non-O1/non-O139 in Germany reveals carbapenemase-producing Vibrio cholerae in coastal waters

    OpenAIRE

    Nadja eBier; Keike eSchwartz; Beatriz eGuerra; Eckhard eStrauch

    2015-01-01

    An increase in the occurrence of potentially pathogenic Vibrio species is expected for waters in Northern Europe as a consequence of global warming. In this context, a higher incidence of Vibrio infections is predicted for the future and forecasts suggest that people visiting and living at the Baltic Sea are at particular risk.This study aimed to investigate antimicrobial resistance patterns among Vibrio vulnificus and Vibrio cholerae non-O1/non-O139 isolates that could pose a public health r...

  1. Caracterización de aislamientos de Vibrio cholerae no-O1, no-O139 asociados a cuadros de diarrea Characterization of Vibrio cholerae non-O1 and non-O139 isolates associated with diarrhea

    Directory of Open Access Journals (Sweden)

    S. González Fraga

    2009-03-01

    its virulence factors by PCR, antimicrobial susceptibility patterns and genetic diversity by pulsed-field gel electrophoresis. Eight virulence patterns were obtained although no isolate was positive for the cholera toxin or the thermostable toxin. Four isolates were positive for the type three secretion system. The 17.6% of the isolates were resistant or intermediate to ampicillin and 5.9% were resistant to trimethoprim-sulfamethoxazole. By SfiI-PFGE, all isolates were genetically very diverse, as 27 different patterns were identified in 29 typeable isolates by pulsed-field gel electrophoresis. Although it has a low incidence, V. cholerae continues to be a causative agent of diarrhea in children, who are affected by a variety of circulating strains of V. cholerae non-O1, non-O139.

  2. 广州海珠地区非O1/非O139群霍乱弧菌流行状况调查及生物学特征研究%Epidemic condition and biological characteristics of non-O1/non-O139 vibrio cholerae in Haizhu District of Guangzhou

    Institute of Scientific and Technical Information of China (English)

    许少洪; 李映霞; 李少彤; 吴琪; 孙凤琪; 黄芳; 曾爱芳

    2010-01-01

    Objective To understand the epidemic condition, distribution and biological characteristics of non-O1/non-O139 vibrio cholerae from 2001 to 2009 in Haizhu District, to provide a scientific basis for the prevention and control of acute diarrhea. Methods Referring to the detecting method written in "Cholera control handbook"in the fifth edition,764 specimens from outside environment (including the water in the Pearl River, drinking water, water for breeding fish, aquatic products and delicatessen foods), 189 specimens of healthy population and 3398 intestinal samples of patients with diarrhea, summing up to 4351 specimens for non-O1/non-O139 vibrio cholerae test. Results 4351 speciments were detected of 101 strains of non O1/non O139 vibrio cholerae, the total detection rate was 2. 32%;66 strains were identified by serotyping and grouped into 26 different serotypes, the typing rate was 65.3%. The strains VBO9,VBO38 and VBO76 were the dominant bacteria. Nine strains of the same type of non-O1/non-O139 vibrio cholerae were found from external environments also from patients with diarrhea, suggesting that there might be a correlation between the two. Conclusion Non-O1/non-O139 vibrio cholerae have diversified serotypes, causing certain infection rate among the population in this region. These bacteria exist extensively in external environment and they are the potential hazard to the citizens.%目的 了解广州海珠地区2001-2009年非O1/非O139群霍乱弧菌的流行、分布状况及生物学特征,为防控该类病原菌引起的急性腹泻病提供科学依据.方法 参照(第5版)中的检测方法,对本区珠江河水、饮用水、养殖水、各种海(水)产品、市售熟食等外环境标本764份、健康人群标本189份及肠道门诊腹泻患者标本3398份,共计4351份标本进行非O1/非O139群霍乱弧菌的检定.结果 4351份标本共检出非O1/非O139群霍乱弧菌101株,总检出率为2.32%;其中有66株可分型,分属于26

  3. Bacteriemia por Vibrio cholerae no-O1, no-O139 en un paciente en hemodiálisis crónica Non-O1, non-O139 Vibrio cholerae bacteremia in a chronic hemodialysis patient

    Directory of Open Access Journals (Sweden)

    Mariela S. Zárate

    2011-06-01

    Full Text Available Vibrio cholerae no-O1, no-O139 es un agente poco frecuente como causal de bacteriemias y no hay informes que documenten su presencia en pacientes en hemodiálisis crónica. Se describe el caso de una paciente en hemodiálisis crónica que presentó un cuadro de sepsis, por lo cual inició un tratamiento con vancomicina y ceftacidima. Al cabo de seis horas y media de incubación en el sistema BACT/ALERT de hemocultivo, se evidenció la presencia de bacilos curvos gram negativos, posteriormente identificados como Vibrio cholerae mediante pruebas bioquímicas convencionales y el uso de los kits API 20 NE y VITEK 2. La evaluación del serogrupo y de la presencia de factores de patogenicidad, realizada en el laboratorio de referencia, determinó que el microorganismo hallado pertenecía al serogrupo no-O1, no-O139. No se detectó la toxina de cólera, tampoco el factor de colonización ni la toxina termoestable. El aislamiento presentó sensibilidad frente a ampicilina, trimetoprima-sulfametoxazol, ciprofloxacina, tetraciclina, ceftacidima y cefotaxima por el método de difusión con discos y por VITEK 2. La paciente cumplió 14 días de tratamiento con ceftacidima endovenosa, con evolución favorable.Non-O1, and non-O139 Vibrio cholerae is an infrequent cause of bacteremia. There are no reports of such bacteremia in chronic hemodialysis patients. This work describes the case of a chronic hemodialysis patient that had an episode of septicemia associated with dialysis. Blood cultures were obtained and treatment was begun with vancomycin and ceftazidime. After 6.5 hours of incubation in the Bact/Alert system there is evidence of gram-negative curved bacilli that were identified as Vibrio cholerae by conventional biochemical tests, API 20 NE and the VITEK 2 system. This microorganism was sent to the reference laboratory for evaluation of serogroup and virulence factors and was identified as belonging to the non-O1 and non-O139 serogroup. The cholera

  4. 浙江省非O1、非O139群霍乱弧菌快速检测与毒力基因研究%Rapid detection of non O1 and non O139 Vibrio cholerae and their virulence genes in Zhejiang province

    Institute of Scientific and Technical Information of China (English)

    罗芸; 叶菊莲; 金大智; 张政; 王复甦; 徐宝祥

    2011-01-01

    目的 建立一种快速检测非O1、非O139群霍乱弧菌方法,并对浙江省部分地区海水产品中非O1、非O139 群霍乱弧菌及其携带毒力基因开展快速检测.方法 采用三糖斜面、氧化酶实验、粘丝实验、无盐胨水等简单生化进行初筛,对全部结果阳性的菌株用聚合酶链反应(PCR)方法检测霍乱弧菌外膜蛋白OmpW以及毒力基因ctxA、hlyA和toxR.结果 按照方法用三糖斜面初筛后共有504份样本阳性,其中氧化酶、粘丝和无盐胨水全部为阳性的有434份;有388份样本OmpW PCR结果为阳性,其中ctxA结果均为阴性,toxR阳性hlyA阳性的有225株.结论 建立的快速检测方法提高了非O1、非O139群霍乱弧菌的检出率,缩短了检测时间,节约了检测成本.浙江省非O1、非O139群霍乱弧菌在海水产品中广泛存在,应对其致病性提高警惕,加强监测.%Objective To establish a rapid detection assay to detect non O1 and non-O139 Vibrio cholerae in sea foods and their virulence genes in Zhejiang province. Methods Non Ol and non O139 Vibrio cholerae strains were detected by using triple sugar tube, oxidase test, ropiness test and saltless peptone water test, then OmpW,ctxA、hlyA and toxR genes of Vibrio cholerae were detected by PCR assay. Results Totally 504 sample were positive by using triple sugar tube, in addition, 434 samples were positive in other 3 tests. Totally 388 strains were OmpW gene positive, but ctxA gene negative and 225 strains were both hlyA and toxR gene positive. Conclusion The established rapid assay could increase the detection rate of non Ol and non O139 Vibrio cholerae, shorten the detection time and reduce test cost. Non Ol and non-O139 Vibrio cholerae generally exist in sea foods in Zhejiang province. It is important to fully understand their pathogenicities and strengthen the disease surveillance.

  5. Molecular analysis on non-O1 and non-O139 Vibrio cholerae isolates%非O1/非O139群霍乱弧菌感染病例分离株分子流行病学分析

    Institute of Scientific and Technical Information of China (English)

    陈道利; 胡万富; 詹圣伟; 景怀琦; 阚飙; 张萍; 王多春; 陈谨; 喻佰启; 程险峰; 刁保卫; 周海健; 朱明

    2012-01-01

    目的分析安徽省马鞍山市连续2个月内监测到的6例具有霍乱疑似症状、感染非O1/非O139群霍乱弧菌的病例,判断疫情的聚集性.方法 对病例分离株进行生化和血清型别鉴定以及溶血试验,药敏试验检测抗生素耐药谱,应用荧光PCR和常规PCR进行霍乱弧菌特异基因、毒力及其相关基因的检测,包括ompW、ctx 、tcpA、toxR、hlyA 、zot、ace、rstR和gⅢCTX,应用脉冲场凝胶电泳(PFGE)分析其分子型别.结果 生化鉴定和血清学试验鉴别腹泻病例6株菌株为非O1/非O139霍乱弧菌,均产生β溶血;14种药物中有12种属于全部敏感;荧光PCR检测霍乱弧菌特异性基因ompW均为阳性,ctx、tcpA 、zot、ace、rstR和gⅢCTX基因均为阴性,toxR 、hlyA基因有5株菌扩增阳性,1株菌(1001434446)为阴性;PFGE显示6株菌带型均不相同,但有2株非常相似,分离株与霍乱弧菌产毒株相似性很低.结论 6例感染非产毒的非O1/非O139群霍乱弧菌病例发病虽相对集中,但属于散发病例,在局部地区频繁出现,提示其公共卫生意义不可忽视.%Objective According to results from the two-month consecutive surveillance program in Maanshan,six suspected cases of non-O1 non-O139 Vibrio (V.) cholerae infection,were found that called for identification of pathogens as well as molecular-epidemiological analysis to determine the aggregation of the epidemic situation.Methods Biochemical and serotype identification,hemolysis test,and drug sensitive test were used to detect the drug resistance spectrum.Real-time PCR and conventional PCR were used to detect the presence of V.cholerae specific genes,virulent genes and its related genes,including ompW,ctx,tcpA,toxR,hlyA,zot,ace,rstR and g ⅢCTX.Pulsed-field gel electrophoresis (PFGE) was used to analyze the molecular type of strains.Results All the six isolates of non-O 1 non-O 139 V.cholerae were identified by biochemical and serologic tests,and appeared to be

  6. Identification and virulence gene detection of non-O1 and non-O139 Vibrio chol-erae isolates causing septicemia%致血流感染非 O1群非 O139群霍乱弧菌的鉴定及毒力基因检测

    Institute of Scientific and Technical Information of China (English)

    邹玖明; 张爱平; 李智山; 杨燕; 赵建忠

    2014-01-01

    Objective To identify an suspected Vibrio cholerae isolated from Xiangyang Central Hospital and characterize the strain in terms of antibiotic resistance and relevant virulence genes.Methods Pathogen identification and susceptibility testing were completed with MicroScan WalkAway 40 Automated Microbiology System.Slide agglutination was used for serotyping. PCR and sequencing technology were employed for 16s RNA gene analysis.PCR technique was used to detect six major viru-lence genes.Results This suspectedVibrio cholerae isolate was confirmed as non-O1 and non-O139 Vibrio cholerae .Suscep-tibility testing results indicated that the strain was sensitive to ampicillin,chloramphenicol,trimethoprim-sulfamethoxazole, and tetracycline.16s RNA gene sequence analysis showed 100% homologous with the registered sequence in National Center for Biotechnology Information database.Virulence genes rtxC and toxR were identified.The other virulence genes such as tcpAET,ctxA,hlyA,and tcpACL were negative.Conclusions This suspected Vibrio cholerae isolate is confirmed as non-O1 and non-O139 Vibrio cholerae .The pathogenic factors may be related to the virulence genes rtxC and toxR.%目的:对襄阳市中心医院分离1株疑似霍乱弧菌进行鉴定及药物敏感性试验,并检测其主要毒力基因。方法利用MicroScan WalkAway 40鉴定仪进行生化鉴定及药物敏感性试验,玻片凝集法确定其血清型别,应用 PCR 及测序技术分析其16SrRNA 基因;PCR 检测其6个毒力基因。结果经鉴定,该株疑似霍乱菌株为非 O1群非 O139群霍乱弧菌,经16SrRNA分析与美国国家生物技术信息中心数据库中霍乱弧菌相似性达100%。药敏试验结果显示该菌对氨苄西林、氯霉素、甲氧苄啶-磺胺甲口恶唑、四环素均敏感,毒力基因检测 rtxC 和 toxR 阳性,tcpAET、ctx A 、hlyA、tcpACL 阴性。结论该株疑似霍乱弧菌为非 O1群非 O139群霍乱弧菌,其致病与 rtxC、toxR 毒力基因有关。

  7. gbpA as a Novel qPCR Target for the Species-Specific Detection of Vibrio cholerae O1, O139, Non-O1/Non-O139 in Environmental, Stool, and Historical Continuous Plankton Recorder Samples.

    Science.gov (United States)

    Vezzulli, Luigi; Stauder, Monica; Grande, Chiara; Pezzati, Elisabetta; Verheye, Hans M; Owens, Nicholas J P; Pruzzo, Carla

    2015-01-01

    The Vibrio cholerae N-acetyl glucosamine-binding protein A (GbpA) is a chitin-binding protein involved in V. cholerae attachment to environmental chitin surfaces and human intestinal cells. We previously investigated the distribution and genetic variations of gbpA in a large collection of V. cholerae strains and found that the gene is consistently present and highly conserved in this species. Primers and probe were designed from the gbpA sequence of V. cholerae and a new Taq-based qPCR protocol was developed for diagnostic detection and quantification of the bacterium in environmental and stool samples. In addition, the positions of primers targeting the gbpA gene region were selected to obtain a short amplified fragment of 206 bp and the protocol was optimized for the analysis of formalin-fixed samples, such as historical Continuous Plankton Recorder (CPR) samples. Overall, the method is sensitive (50 gene copies), highly specific for V. cholerae and failed to amplify strains of the closely-related species Vibrio mimicus. The sensitivity of the assay applied to environmental and stool samples spiked with V. cholerae ATCC 39315 was comparable to that of pure cultures and was of 102 genomic units/l for drinking and seawater samples, 101 genomic units/g for sediment and 102 genomic units/g for bivalve and stool samples. The method also performs well when tested on artificially formalin-fixed and degraded genomic samples and was able to amplify V. cholerae DNA in historical CPR samples, the earliest of which date back to August 1966. The detection of V. cholerae in CPR samples collected in cholera endemic areas such as the Benguela Current Large Marine Ecosystem (BCLME) is of particular significance and represents a proof of concept for the possible use of the CPR technology and the developed qPCR assay in cholera studies.

  8. gbpA as a Novel qPCR Target for the Species-Specific Detection of Vibrio cholerae O1, O139, Non-O1/Non-O139 in Environmental, Stool, and Historical Continuous Plankton Recorder Samples

    Science.gov (United States)

    Vezzulli, Luigi; Stauder, Monica; Grande, Chiara; Pezzati, Elisabetta; Verheye, Hans M.; Owens, Nicholas J. P.; Pruzzo, Carla

    2015-01-01

    The Vibrio cholerae N-acetyl glucosamine-binding protein A (GbpA) is a chitin-binding protein involved in V. cholerae attachment to environmental chitin surfaces and human intestinal cells. We previously investigated the distribution and genetic variations of gbpA in a large collection of V. cholerae strains and found that the gene is consistently present and highly conserved in this species. Primers and probe were designed from the gbpA sequence of V. cholerae and a new Taq-based qPCR protocol was developed for diagnostic detection and quantification of the bacterium in environmental and stool samples. In addition, the positions of primers targeting the gbpA gene region were selected to obtain a short amplified fragment of 206 bp and the protocol was optimized for the analysis of formalin-fixed samples, such as historical Continuous Plankton Recorder (CPR) samples. Overall, the method is sensitive (50 gene copies), highly specific for V. cholerae and failed to amplify strains of the closely-related species Vibrio mimicus. The sensitivity of the assay applied to environmental and stool samples spiked with V. cholerae ATCC 39315 was comparable to that of pure cultures and was of 102 genomic units/l for drinking and seawater samples, 101 genomic units/g for sediment and 102 genomic units/g for bivalve and stool samples. The method also performs well when tested on artificially formalin-fixed and degraded genomic samples and was able to amplify V. cholerae DNA in historical CPR samples, the earliest of which date back to August 1966. The detection of V. cholerae in CPR samples collected in cholera endemic areas such as the Benguela Current Large Marine Ecosystem (BCLME) is of particular significance and represents a proof of concept for the possible use of the CPR technology and the developed qPCR assay in cholera studies. PMID:25915771

  9. gbpA as a Novel qPCR Target for the Species-Specific Detection of Vibrio cholerae O1, O139, Non-O1/Non-O139 in Environmental, Stool, and Historical Continuous Plankton Recorder Samples.

    Directory of Open Access Journals (Sweden)

    Luigi Vezzulli

    Full Text Available The Vibrio cholerae N-acetyl glucosamine-binding protein A (GbpA is a chitin-binding protein involved in V. cholerae attachment to environmental chitin surfaces and human intestinal cells. We previously investigated the distribution and genetic variations of gbpA in a large collection of V. cholerae strains and found that the gene is consistently present and highly conserved in this species. Primers and probe were designed from the gbpA sequence of V. cholerae and a new Taq-based qPCR protocol was developed for diagnostic detection and quantification of the bacterium in environmental and stool samples. In addition, the positions of primers targeting the gbpA gene region were selected to obtain a short amplified fragment of 206 bp and the protocol was optimized for the analysis of formalin-fixed samples, such as historical Continuous Plankton Recorder (CPR samples. Overall, the method is sensitive (50 gene copies, highly specific for V. cholerae and failed to amplify strains of the closely-related species Vibrio mimicus. The sensitivity of the assay applied to environmental and stool samples spiked with V. cholerae ATCC 39315 was comparable to that of pure cultures and was of 102 genomic units/l for drinking and seawater samples, 101 genomic units/g for sediment and 102 genomic units/g for bivalve and stool samples. The method also performs well when tested on artificially formalin-fixed and degraded genomic samples and was able to amplify V. cholerae DNA in historical CPR samples, the earliest of which date back to August 1966. The detection of V. cholerae in CPR samples collected in cholera endemic areas such as the Benguela Current Large Marine Ecosystem (BCLME is of particular significance and represents a proof of concept for the possible use of the CPR technology and the developed qPCR assay in cholera studies.

  10. Water sources as reservoirs of Vibrio cholerae O1 and non-O1 strains in Bepanda, Douala (Cameroon): relationship between isolation and physico-chemical factors.

    Science.gov (United States)

    Akoachere, Jane-Francis Tatah Kihla; Mbuntcha, Christelle Kwedjeu Pulcherie

    2014-07-30

    Cholera has been endemic in Douala since 1971. Most outbreaks start from Bepanda, an overcrowded neighbourhood with poor hygiene and sanitary conditions. We investigated water sources in Bepanda as reservoirs of Vibrio cholerae, the causative agent of cholera, determined its antibiotic susceptibility and some physico-chemical characteristics that could maintain the endemicity of this organism in Bepanda. Three hundred and eighteen water samples collected from 45 wells, 8 taps and 1 stream from February to July 2009 were analyzed for V. cholerae using standard methods. Isolates were characterized morphologically, biochemically and serologically. The disc diffusion technique was employed to investigate antibiotic susceptibility. Differences in prevalence of organism between seasons were analysed. Correlation strength and direction of association between physico-chemical parameters and occurrence of V. cholerae was analyzed using the Kendall tau_b non-parametric correlation. This was further confirmed with the forward-stepwise binary logistic regression. Eighty-seven (27.4%) samples were positive for V. cholerae. Isolation was highest from wells. The organism was isolated in the rainy season and dry season but the frequency of isolation was significantly higher (χ2 = 7.009, df = 1, P = 0.008) in the rainy season. Of the 96 confirmed V. cholerae isolates, 32 (33.3%) belonged to serogroup O1 and 64 (66.6%) were serogroup non-O1/non-O139. Isolates from tap (municipal water) were non-O1/non-O139 strains. Salinity had a significant positive correlation with isolation in the dry season (+0.267, P = 0.015) and rainy season (+0.223, P = 0.028). The forward-stepwise method of binary logistic regression indicated that as pH (Wald = 11.753, df = 1), P = 0.001) increased, odds of isolation of V. cholerae also increased (B = 1.297, S.E = 0.378, Exp(B) = 3.657). All isolates were sensitive to ciprofloxacin and ofloxacin. Multi-drug resistance was predominant among the non-O1/non-O

  11. 异育银鲫非O1/非O139群霍乱弧菌的分离及鉴定%Isolation and identification of non-O1/non-O139 Vibrio cholerae from gibel carp

    Institute of Scientific and Technical Information of China (English)

    秦蕾; 徐静; 张晓君

    2013-01-01

    为鉴定引起异育银鲫发病的疫情的病原,本研究从病鱼体内分离到细菌分离株,经动物回归试验证明为导致异育银鲫发病的致病原.对病原菌株进行形态学、生理生化测定以及16S rDNA序列分析,显示该菌株与霍乱弧菌(Vibrio cholerae)表型特征一致,而且在系统发育树中也是与霍乱弧菌相聚类,两者16S rDNA序列相似性高达99.93%.综合表型特征与基因序列分析的结果表明,该病原菌株应归属于霍乱弧菌.血清型鉴定为非O1/非O139群霍乱弧菌.药物敏感性试验结果显示该株霍乱弧菌对喹诺酮类、头孢类、氨基糖苷类、大环内酯类,四环素类以及β-内酰胺类等药物敏感.%An infectious disease occurred in a gibel carp farm in 2010. The dominant bacteria were isolated from diseased fish and proved to be causal agent of the disease by experimental infection in gibel carp. Conventional physiological and biochemical tests showed that the isolates had phenotypic characteristics in according with reference strain of Vibrio cholerae. And 16S rDNA sequence was analyzed revealing that it was most closely related to V.cholerae with 99.93% similarity. Therefore, the isolates were finally identified as V.cholerae. Antibiotic susceptibility testing showed that the isolates were sensitive to quinolones, cephems, aminoglycosides, macrolide, tetracyclines and β-lactams.

  12. Detection of ctx gene positive non-O1/non-O139 V. cholerae in shrimp aquaculture environments

    OpenAIRE

    Madhusudana, Rao B.; Surendran, P. K.

    2011-01-01

    Water and post-larvae samples from black tiger (Penaeus monodon) shrimp hatcheries; pond water, pond sediment and shrimp from aquaculture farms were screened for the presence of V. cholerae. A V. cholerae-duplex PCR method was developed by utilizing V. cholerae species specific sodB primers and ctxAB genes specific primers. Incidence of V. cholerae was not observed in shrimp hatchery samples but was noticed in aquaculture samples. The incidence of V. cholerae was higher in pond water (7.6%) t...

  13. Presence of CTX gene cluster in environmental non-O1/O139 Vibrio cholerae and its potential clinical significance

    Directory of Open Access Journals (Sweden)

    B Bakhshi

    2012-01-01

    Full Text Available Purpose: The aim of this study was to understand the epidemiological linkage of clinical and environmental isolates of Vibrio cholerae and to determine their genotypes and virulence genes content. Materials and Methods: A total of 60 V. cholerae strains obtained from clinical specimens (n = 40 and surface waters (n = 20 were subjected to genotyping using PFGE and determination of their virulence-associated gene clusters. Result: PCR analysis showed the presence of chromosomally located hly and RTX genetic elements in 100% and 90% of the environmental isolates, respectively. The phage-mediated genetic elements such as CTX, TLC and VPI were detected in 5% of the environmental isolates suggesting that the environmental isolates cannot acquire certain mobile gene clusters. A total of 4 and 18 pulsotypes were obtained among the clinical and environmental V. cholerae isolates, respectively. Non-pathogenic environmentally isolated V. cholerae constituted a distinct cluster with one single non-O1, non-O139 strain (EP6 carrying the virulence genes similar to the epidemic strains. This may suggest the possible potential of conversion of non-pathogenic to a pathogenic environmental strain. Conclusions: The emergence of a single environmental isolate in our study containing the pathogenicity genes amongst the diverse non-pathogenic environmental isolates needs to be further studied in the context of V. cholerae pathogenicity sero-coversion.

  14. Distribution and content of class 1 integrons in different Vibrio cholerae O-serotype strains isolated in Thailand

    DEFF Research Database (Denmark)

    Dalsgaard, Anders; Forslund, Anita; Serichantalergs, Oralak

    2000-01-01

    only a single antibiotic resistance gene. Although resistance genes in class 1 integrons were found in strains from the same epidemic, as well as in unrelated non-O1, non-O139 strains isolated from children with diarrhea, they were found to encode only some of the antibiotic resistance expressed......-kb self-transmissible plasmid found in three O1 strains isolated in 1982 contained the aadB gene cassette. Surprisingly, several strains harbored two integrons containing different cassettes. Thus, class 1 integrons containing various resistance gene cassettes are distributed among different V...

  15. Characterization of Vibrio cgolerae non-O1 serogroups obtained from an outbreak of diarrhea in Lima, Peru.

    Science.gov (United States)

    Dalsgaard, A; Albert, M J; Taylor, D N; Shimada, T; Meza, R; Serichantalergs, O; Echeverria, P

    1995-10-01

    study provides further evidence that V. chlorae non-O1 non-O139 strains have diarrhegenic potential for humans through a yet-undefined mechanism(s) and that such strains can cause outbreaks.

  16. CARB-9, a Carbenicillinase Encoded in the VCR Region of Vibrio cholerae Non-O1, Non-O139 Belongs to a Family of Cassette-Encoded β-Lactamases†

    OpenAIRE

    Petroni, Alejandro; Melano, Roberto G.; Saka, Héctor A.; Garutti, Alicia; Mange, Laura; Pasterán, Fernando; Rapoport, Melina; Miranda, Mariana; Faccone, Diego; Rossi, Alicia; Hoffman, Paul S.; Galas, Marcelo F.

    2004-01-01

    The gene blaCARB-9 was located in the Vibrio cholerae super-integron, but in a different location relative to blaCARB-7. CARB-9 (pI 5.2) conferred β-lactam MICs four to eight times lower than those conferred by CARB-7, differing at Ambler's positions V97I, L124F, and T228K. Comparison of the genetic environments of all reported blaCARB genes indicated that the CARB enzymes constitute a family of cassette-encoded β-lactamases.

  17. CARB-9, a Carbenicillinase Encoded in the VCR Region of Vibrio cholerae Non-O1, Non-O139 Belongs to a Family of Cassette-Encoded β-Lactamases†

    Science.gov (United States)

    Petroni, Alejandro; Melano, Roberto G.; Saka, Héctor A.; Garutti, Alicia; Mange, Laura; Pasterán, Fernando; Rapoport, Melina; Miranda, Mariana; Faccone, Diego; Rossi, Alicia; Hoffman, Paul S.; Galas, Marcelo F.

    2004-01-01

    The gene blaCARB-9 was located in the Vibrio cholerae super-integron, but in a different location relative to blaCARB-7. CARB-9 (pI 5.2) conferred β-lactam MICs four to eight times lower than those conferred by CARB-7, differing at Ambler's positions V97I, L124F, and T228K. Comparison of the genetic environments of all reported blaCARB genes indicated that the CARB enzymes constitute a family of cassette-encoded β-lactamases. PMID:15388476

  18. High genetic diversity of Vibrio cholerae in the European lake Neusiedler See is associated with intensive recombination in the reed habitat and the long-distance transfer of strains.

    Science.gov (United States)

    Pretzer, Carina; Druzhinina, Irina S; Amaro, Carmen; Benediktsdóttir, Eva; Hedenström, Ingela; Hervio-Heath, Dominique; Huhulescu, Steliana; Schets, Franciska M; Farnleitner, Andreas H; Kirschner, Alexander K T

    2017-01-01

    Coastal marine Vibrio cholerae populations usually exhibit high genetic diversity. To assess the genetic diversity of abundant V. cholerae non-O1/non-O139 populations in the Central European lake Neusiedler See, we performed a phylogenetic analysis based on recA, toxR, gyrB and pyrH loci sequenced for 472 strains. The strains were isolated from three ecologically different habitats in a lake that is a hot-spot of migrating birds and an important bathing water. We also analyzed 76 environmental and human V. cholerae non-O1/non-O139 isolates from Austria and other European countries and added sequences of seven genome-sequenced strains. Phylogenetic analysis showed that the lake supports a unique endemic diversity of V. cholerae that is particularly rich in the reed stand. Phylogenetic trees revealed that many V. cholerae isolates from European countries were genetically related to the strains present in the lake belonging to statistically supported monophyletic clades. We hypothesize that the observed phenomena can be explained by the high degree of genetic recombination that is particularly intensive in the reed stand, acting along with the long distance transfer of strains most probably via birds and/or humans. Thus, the Neusiedler See may serve as a bioreactor for the appearance of new strains with new (pathogenic) properties. © 2016 The Authors. Environmental Microbiology published by Society for Applied Microbiology and John Wiley & Sons Ltd.

  19. Clinical manifestations of non-O1 Vibrio cholerae infections.

    Directory of Open Access Journals (Sweden)

    Yen-Ting Chen

    Full Text Available BACKGROUND: Infections caused by non-O1 Vibrio cholera are uncommon. The aim of our study was to investigate the clinical and microbiological characteristics of patients with non-O1 V. cholera infections. METHODS: The clinical charts of all patients with non-O1 V. cholera infections and who were treated in two hospitals in Taiwan were retrospectively reviewed. RESULTS: From July 2009 to June 2014, a total of 83 patients with non-O1 V. cholera infections were identified based on the databank of the bacteriology laboratories of two hospitals. The overall mean age was 53.3 years, and men comprised 53 (63.9% of the patients. Liver cirrhosis and diabetes mellitus were the two most common underlying diseases, followed by malignancy. The most common type of infection was acute gastroenteritis (n = 45, 54.2%, followed by biliary tract infection (n = 12, 14.5% and primary bacteremia (n = 11, 13.3%. Other types of infection, such as peritonitis (n = 5, 6.0%, skin and soft tissue infection (SSTI (n = 5, 6.0%, urinary tract infection (n = 3, 3.6% and pneumonia (2, 2.4%, were rare. July and June were the most common months of occurrence of V. cholera infections. The overall in-hospital mortality of 83 patients with V. cholera infections was 7.2%, but it was significantly higher for patients with primary bacteremia, hemorrhage bullae, acute kidney injury, acute respiratory failure, or admission to an ICU. Furthermore, multivariate analysis showed that in-hospital mortality was significantly associated with acute respiratory failure (odds ratio, 60.47; 95% CI, 4.79-763.90, P = 0.002. CONCLUSIONS: Non-O1 V. cholera infections can cause protean disease, especially in patients with risk factors and during warm-weather months. The overall mortality of 83 patients with non-O1 V. cholera infections was only 7.2%; however, this value varied among different types of infection.

  20. Serotypes of Vibrio cholerae non-O1 isolated from water supplies for human consumption in Campeche, México and their antibiotic susceptibility pattern.

    Science.gov (United States)

    Isaac-Márquez, A P; Lezama-Dávila, C M; Eslava-Campos, C; Navarro-Ocaña, A; Cravioto-Quintana, A

    1998-01-01

    The presence of Vibrio cholerae non-O1 in water supplies for human consumption in the city of Campeche and rural locality of Bécal was investigated. V. cholerae non-O1 was detected in 5.9% of the samples obtained in deep pools of Campeche. Studies conducted in Bécal and neighbourhood of Morelos in Campeche indicated that collected samples harbored V. cholerae non-O1 in 31.5% and 8.7% respectively. There was a particular pattern of distribution of V. cholerae non-O1 serotypes among different studied regions. Accordingly, V. cholerae non-O1 serotype O14 predominated in the deep pools of Campeche and together with V. cholerae non-O1, O155 were preferentially founds in samples taken from intradomiciliary faucets in the neighbourhood of Morelos. Samples from Bécal predominantly presented the serotype O112. 60% and 53.8% of all studied strains of V. cholerae non-O1 proved to be resistant to ampicillin and carbenicillin. 3.1%, 7.7% and 6.2% presented resistant to doxycycline, trimethoprim-sulfamethoxazole and erythromycin respectively. The study showed the necessity of performing a strong epidemiologic surveillance for emergence and distribution of V. cholerae non-O1.

  1. Evidence that a non-O1 Vibrio cholerae produces enterotoxin that is similar but not identical to cholera enterotoxin.

    OpenAIRE

    Yamamoto, K.; Takeda, Y.; Miwatani, T; Craig, J. P.

    1983-01-01

    Cholera-like enterotoxin produced by a non-O1 strain of Vibrio cholerae, S7 (S7 enterotoxin), isolated from human diarrheal stool, was purified, and its physicochemical, biological, and immunological properties were compared with those of cholera enterotoxin from V. cholerae O1 569B (CT) and an enterotoxin produced by another non-O1 V. cholerae (E8498 enterotoxin) reported previously (Yamamoto et al., Infect. Immun. 39:1128-1135, 1983). The purified S7 enterotoxin had physicochemical properti...

  2. Occurrence of virulence genes among Vibrio cholerae and Vibrio parahaemolyticus strains from treated wastewaters.

    Science.gov (United States)

    Khouadja, Sadok; Suffredini, Elisabetta; Baccouche, Besma; Croci, Luciana; Bakhrouf, Amina

    2014-10-01

    Pathogenic Vibrio species are an important cause of foodborne illnesses. The aim of this study was to describe the occurrence of potentially pathogenic Vibrio species in the final effluents of a wastewater treatment plant and the risk that they may pose to public health. During the 1-year monitoring, a total of 43 Vibrio strains were isolated: 23 Vibrio alginolyticus, 1 Vibrio cholerae, 4 Vibrio vulnificus, and 15 Vibrio parahaemolyticus. The PCR investigation of V. parahaemolyticus and V. cholerae virulence genes (tlh, trh, tdh, toxR, toxS, toxRS, toxT, zot, ctxAB, tcp, ace, vpi, nanH) revealed the presence of some of these genes in a significant number of strains. Intraspecies variability and genetic relationships among the environmental isolates were analyzed by random amplified polymorphic DNA-PCR (RAPD-PCR). We report the results of the first isolation and characterization of an environmental V. cholerae non-O1 non-O139 and of a toxigenic V. parahaemolyticus strain in Tunisia. We suggest that non-pathogenic Vibrio might represent a marine reservoir of virulence genes that can be transmitted between strains by horizontal transfer.

  3. Comparative genome analysis of non-toxigenic non-O1 versus toxigenic O1 Vibrio cholerae.

    Science.gov (United States)

    Mukherjee, Munmun; Kakarla, Prathusha; Kumar, Sanath; Gonzalez, Esmeralda; Floyd, Jared T; Inupakutika, Madhuri; Devireddy, Amith Reddy; Tirrell, Selena R; Bruns, Merissa; He, Guixin; Lindquist, Ingrid E; Sundararajan, Anitha; Schilkey, Faye D; Mudge, Joann; Varela, Manuel F

    Pathogenic strains of Vibrio cholerae are responsible for endemic and pandemic outbreaks of the disease cholera. The complete toxigenic mechanisms underlying virulence in Vibrio strains are poorly understood. The hypothesis of this work was that virulent versus non-virulent strains of V. cholerae harbor distinctive genomic elements that encode virulence. The purpose of this study was to elucidate genomic differences between the O1 serotypes and non-O1 V. cholerae PS15, a non-toxigenic strain, in order to identify novel genes potentially responsible for virulence. In this study, we compared the whole genome of the non-O1 PS15 strain to the whole genomes of toxigenic serotypes at the phylogenetic level, and found that the PS15 genome was distantly related to those of toxigenic V. cholerae. Thus we focused on a detailed gene comparison between PS15 and the distantly related O1 V. cholerae N16961. Based on sequence alignment we tentatively assigned chromosome numbers 1 and 2 to elements within the genome of non-O1 V. cholerae PS15. Further, we found that PS15 and O1 V. cholerae N16961 shared 98% identity and 766 genes, but of the genes present in N16961 that were missing in the non-O1 V. cholerae PS15 genome, 56 were predicted to encode not only for virulence-related genes (colonization, antimicrobial resistance, and regulation of persister cells) but also genes involved in the metabolic biosynthesis of lipids, nucleosides and sulfur compounds. Additionally, we found 113 genes unique to PS15 that were predicted to encode other properties related to virulence, disease, defense, membrane transport, and DNA metabolism. Here, we identified distinctive and novel genomic elements between O1 and non-O1 V. cholerae genomes as potential virulence factors and, thus, targets for future therapeutics. Modulation of such novel targets may eventually enhance eradication efforts of endemic and pandemic disease cholera in afflicted nations.

  4. Comparative genome analysis of non-toxigenic non-O1 versus toxigenic O1 Vibrio cholerae

    Science.gov (United States)

    Mukherjee, Munmun; Kakarla, Prathusha; Kumar, Sanath; Gonzalez, Esmeralda; Floyd, Jared T.; Inupakutika, Madhuri; Devireddy, Amith Reddy; Tirrell, Selena R.; Bruns, Merissa; He, Guixin; Lindquist, Ingrid E.; Sundararajan, Anitha; Schilkey, Faye D.; Mudge, Joann; Varela, Manuel F.

    2015-01-01

    Pathogenic strains of Vibrio cholerae are responsible for endemic and pandemic outbreaks of the disease cholera. The complete toxigenic mechanisms underlying virulence in Vibrio strains are poorly understood. The hypothesis of this work was that virulent versus non-virulent strains of V. cholerae harbor distinctive genomic elements that encode virulence. The purpose of this study was to elucidate genomic differences between the O1 serotypes and non-O1 V. cholerae PS15, a non-toxigenic strain, in order to identify novel genes potentially responsible for virulence. In this study, we compared the whole genome of the non-O1 PS15 strain to the whole genomes of toxigenic serotypes at the phylogenetic level, and found that the PS15 genome was distantly related to those of toxigenic V. cholerae. Thus we focused on a detailed gene comparison between PS15 and the distantly related O1 V. cholerae N16961. Based on sequence alignment we tentatively assigned chromosome numbers 1 and 2 to elements within the genome of non-O1 V. cholerae PS15. Further, we found that PS15 and O1 V. cholerae N16961 shared 98% identity and 766 genes, but of the genes present in N16961 that were missing in the non-O1 V. cholerae PS15 genome, 56 were predicted to encode not only for virulence–related genes (colonization, antimicrobial resistance, and regulation of persister cells) but also genes involved in the metabolic biosynthesis of lipids, nucleosides and sulfur compounds. Additionally, we found 113 genes unique to PS15 that were predicted to encode other properties related to virulence, disease, defense, membrane transport, and DNA metabolism. Here, we identified distinctive and novel genomic elements between O1 and non-O1 V. cholerae genomes as potential virulence factors and, thus, targets for future therapeutics. Modulation of such novel targets may eventually enhance eradication efforts of endemic and pandemic disease cholera in afflicted nations. PMID:25722857

  5. Characterization of pathogenicity island prophage in clinical and environmental strains of Vibrio cholerae.

    Science.gov (United States)

    Mohammadi-Barzelighi, H; Bakhshi, B; Rastegar Lari, A; Pourshafie, M R

    2011-12-01

    In this study 86 isolates of Vibrio cholerae were analysed for their adhesive properties and the presence of pathogenicity island genes. With the exception of three isolates, all of the other clinical isolates (92.5%) contained an intact TCP (toxin-co-regulated pilus) gene cluster. In contrast, 95% of all environmental non-O1-non-O139 isolates were negative for the TCP gene cluster. The majority of clinical isolates (82.5%) possessed the complete vibrio pathogenicity island (VPI) gene cluster and had a similar RFLP pattern, while only a single environmental strain possessed an almost complete VPI cluster (lacking 0.4 kb in the tcpA and toxT region). The result showed that the isolates with tcpA(+)/toxT(+) had a strong attachment for HT-29 and Vero cells, whereas isolates with tcpA(+)/toxT(-) or tcpA(-)/toxT(-) genomic characteristics showed no autoagglutination and weak attachment for the cell lines. Two environmental strains (tcpA(-)/toxT(-)) showed strong adhesive properties to the cell lines, indicating that non-fimbrial adhesive factors are involved in the environmental V. cholerae strains in the absence of TCP.

  6. [Surveys on the contamination of marine fish with non-O1 Vibrio cholerae and Vibrio mimicus and food poisoning cases by these organisms].

    Science.gov (United States)

    Kodama, H; Hayashi, M; Gyobu, Y

    1991-02-01

    The present paper describes the relationship between the contamination with non-O1 Vibrio cholerae and Vibrio mimicus of marine fish, with special reference to the seasonal variation and the concentration of contamination, and the actual cases of domestic food poisoning by these organisms. A 10 year survey revealed that non-O1 Vibrio cholerae (non-O1 V. cholerae) strains were frequently isolated from fish during the summer season with some variations from one year to another, and isolates from fish showed similar biological properties to those of isolates from diarrhea cases of over-sea travellers. Experimentally enteropathogenic strains were included among these isolates. Vibrio mimicus (V. mimicus) strains were also isolated from fish, the frequency being not so high as in the case of non-O1 V. cholerae Strains of serovar O-41 which was most predominant among strains from diarrhea cases were also detected among the isolates from fish. The viable cell counts, however, were very small with regard to both non-O1 V. cholerae and V. mimicus From these observations, factors causing food poisoning by non-O1 V. cholerae or V. mimicus seemed to be essentially similar to those by Vibrio parahaemolyticus (V. parahaemolyticus); that is, the food poisoning by non-O1 V. cholerae or V. mimicus is apt to occur in the summer season and is caused by the consumption of raw fish, although the frequency might be significantly low in comparison to that of V. parahaemolyticus. The actual cases of the domestic food poisoning by non-O1 V. cholerae or V. mimicus were retrospectively surveyed by the literature.(ABSTRACT TRUNCATED AT 250 WORDS)

  7. Antibiotic resistance of Vibrio cholera strains isolated from imported crocodiles from Thailand%泰国进口鳄鱼霍乱弧茵药敏试验

    Institute of Scientific and Technical Information of China (English)

    陈冬娥; 陈冠武; 苏建晖; 许先凯

    2012-01-01

    Twelve Vibrio cholera strains were isolated from sixty anal swabs in sampling inspection of the Crocodiles imported from Thailand. It was confirmed that the strains were non-O1, non-O139 Vibrio choleras by biochemical test and serological identification. Eighteen drugs were used in the antibiotic resistance test. The test showed that all the strains were sensitive to most drugs, moderately susceptible to acheomycin and resistance to ampicillin and piperacillin.%在某鳄鱼养殖场抽检的60份泰国进口鳄鱼肛拭子样品中,有12份检出霍乱弧菌。通过生化试验和血清学分型等鉴定,确认12株霍乱弧菌均为非0。非0。。群霍乱弧菌。采用18种抗菌药物进行药敏试验,结果显示所有菌株对大多数抗菌药物高度敏感,对四环素等药物中度敏感,对氨苄青霉素和氧呱嗪青霉素不敏感。

  8. Nontoxigenic Vibrio cholerae non-O1/O139 isolate from a case of human gastroenteritis in the U.S. Gulf Coast.

    Science.gov (United States)

    Hasan, Nur A; Rezayat, Talayeh; Blatz, Peter J; Choi, Seon Young; Griffitt, Kimberly J; Rashed, Shah M; Huq, Anwar; Conger, Nicholas G; Colwell, Rita R; Grimes, D Jay

    2015-01-01

    An occurrence of Vibrio cholerae non-O1/O139 gastroenteritis in the U.S. Gulf Coast is reported here. Genomic analysis revealed that the isolate lacked known virulence factors associated with the clinical outcome of a V. cholerae infection but did contain putative genomic islands and other accessory virulence factors. Many of these factors are widespread among environmental strains of V. cholerae, suggesting that there might be additional virulence factors in non-O1/O139 V. cholerae yet to be determined. Phylogenetic analysis revealed that the isolate belonged to a phyletic lineage of environmental V. cholerae isolates associated with sporadic cases of gastroenteritis in the Western Hemisphere, suggesting a need to monitor non-O1/O139 V. cholerae in the interest of public health.

  9. [Studies on the enteropathogenic mechanism of non-O1 Vibrio cholerae. I. Enteropathogenicity of clinical and environmental isolates].

    Science.gov (United States)

    Gyobu, Y; Kodama, H; Sato, S

    1991-05-01

    Enteropathogenicity and plasmid DNA of clinical and environmental isolates of non-O1 V. cholerae were examined. Results were as follows: 1). The frequencies of enteropathogenic strains judged by the results from both ligated rabbit ileal loop (RIL) and suckling mouse tests were 36/38 (95%) for isolates from overseas travellers, 15/15 (100%) for isolates from food poisoning, 33/44 (75%) for isolates from fish and sea water, and 1/10 (10%) for isolates from river water. 2). Plasmid DNA was detected in eight of the 40 isolates examined, but the presence of plasmid did not correlate with enteropathogenicity. These results indicate that approximately three fourths of the strains isolated from fish and sea water are enteropathogenic, and that the genes controlling the enteropathogenicity of this organism probably exist in chromosomal DNA.

  10. Non-O1 Vibrio cholerae in Thailand: homology with cloned cholera toxin genes.

    OpenAIRE

    Hanchalay, S; Seriwatana, J; Echeverria, P.; Holmgren, J.; Tirapat, C.; Moseley, S L; Taylor, D N

    1985-01-01

    We examined 281 non-O1 Vibrio cholerae isolates from Thailand for homology with genes coding for cholera toxin. Five isolates from environmental sources were homologous with the cholera toxin gene probe and produced both the A and B subunits of cholera toxin.

  11. Genetic relatedness of selected clinical and environmental non-O1/O139 Vibrio cholerae.

    Science.gov (United States)

    Aydanian, Antonina; Tang, Li; Chen, Yuansha; Morris, J Glenn; Olsen, Peter; Johnson, Judith A; Nair, G Balakrish; Stine, O Colin

    2015-08-01

    In an attempt to better understand the non-O1/O139 isolates of Vibrio cholerae, a systematic study of clinical and environmental isolates collected from various geographical locations between the years 1932 and 1998 was conducted. Ninety-nine V. cholerae isolates collected from clinical and environmental sources from various geographical regions between 1932 and 1998 were studied by sequencing seven housekeeping genes. Genetic relatedness was defined by multiple methods that allow for the observed high levels of recombination. Four V. cholerae subpopulations were determined. One subpopulation contained mostly environmental isolates, a second contained the cholera toxin-positive serogroup O1/O139 isolates, and the other two subpopulations were enriched for non-O1/O139 clinical isolates that were frequently clonally related to each other. The data suggest that many of these non-O1/O139 clinical isolates were phylogenetically related to common ancestors, even though the isolates had been collected up to 36 years apart and from different countries or continents. Published by Elsevier Ltd.

  12. Distribution of virulence-associated genes and genetic relationships in non-O1/O139 Vibrio cholerae aquatic isolates from China.

    Science.gov (United States)

    Li, Fengjuan; Du, Pengcheng; Li, Baisheng; Ke, Changwen; Chen, Aiping; Chen, Jie; Zhou, Haijian; Li, Jie; Morris, J Glenn; Kan, Biao; Wang, Duochun

    2014-08-01

    Non-O1/O139 Vibrio cholerae is naturally present in aquatic ecosystems and has been linked with cholera-like diarrhea and local outbreaks. The distribution of virulence-associated genes and genetic relationships among aquatic isolates from China are largely unknown. In this study, 295 aquatic isolates of V. cholerae non-O1/O139 serogroups from different regions in China were investigated. Only one isolate was positive for ctxB and harbored a rare genotype; 10 (3.4%) isolates carried several types of rstR sequences, eight of which carried rare types of toxin-coregulated pili (tcpA). Furthermore, 16 (5.4%) isolates carried incomplete (with partial open reading frames [ORFs]) vibrio seventh pandemic island I (VSP-I) or VSP-II clusters, which were further classified as 11 novel types. PCR-based analyses revealed remarkable variations in the distribution of putative virulence genes, including mshA (95.6%), hlyA (95.3%), rtxC (89.8%), rtxA (82.7%), IS1004 (52.9%), chxA (30.2%), SXT (15.3%), type III secretion system (18.0%), and NAG-ST (3.7%) genes. There was no correlation between the prevalence of putative virulence genes and that of CTX prophage or TCP genes, whereas there were correlations among the putative virulence genes. Further multilocus sequence typing (MLST) placed selected isolates (n = 70) into 69 unique sequence types (STs), which were different from those of the toxigenic O1 and O139 counterparts, and each isolate occupied a different position in the MLST tree. The V. cholerae non-O1/O139 aquatic isolates predominant in China have high genotypic diversity; these strains constitute a reservoir of potential virulence genes, which may contribute to evolution of pathogenic isolates. Copyright © 2014, American Society for Microbiology. All Rights Reserved.

  13. Development of a PCR-restriction fragment length polymorphism assay for detection and subtyping of cholix toxin variant genes of Vibrio cholerae.

    Science.gov (United States)

    Awasthi, Sharda Prasad; Asakura, Masahiro; Neogi, Sucharit Basu; Hinenoya, Atsushi; Ramamurthy, T; Yamasaki, Shinji

    2014-05-01

    Cholix toxin (ChxA) is an exotoxin reported in Vibrio cholerae non-O1/non-O139. Apart from its prototype (ChxA I) we have recently identified two novel variants of this toxin, ChxA II and ChxA III. Our previous investigations indicated that the first two variants may instigate extra-intestinal infections and ChxA II can be more lethal than ChxA I in mice. However, all three cholix toxins (ChxA I to III) failed to show any enterotoxicity in rabbit ileal loops. In this study we developed a PCR-restriction fragment length polymorphism (RFLP) assay to differentiate all three chxA variants to further understand the importance of each subtype. By using 53 V. cholerae non-O1/non-O139 strains harbouring chxA genes, which were previously categorized by sequencing, and various other strains as negative controls, the PCR-RFLP assay showed 100 % typability and specificity. Furthermore, when applied to differentiate additional V. cholerae strains, which were also screened for the chxA gene by colony hybridization, this assay identified chxA I and chxA II genes among 18.5 % and 4.5 % of non-O1/non-O139 strains (n = 178), respectively. One non-O1/non-O139 strain was untypable due to the insertion of an IS911-like element. Interestingly, the chxA I gene was detected in 10 out of 137 cholera toxin gene-negative V. cholerae O1 strains. These results suggest that the PCR-RFLP assay developed in this study can be a rapid and simple method to differentiate the chxA subtypes.

  14. Occurrence and Expression of Luminescence in Vibrio cholerae▿

    Science.gov (United States)

    Grim, Christopher J.; Taviani, Elisa; Alam, Munirul; Huq, Anwar; Sack, R. Bradley; Colwell, Rita R.

    2008-01-01

    Several species of the genus Vibrio, including Vibrio cholerae, are bioluminescent or contain bioluminescent strains. Previous studies have reported that only 10% of V. cholerae strains are luminescent. Analysis of 224 isolates of non-O1/non-O139 V. cholerae collected from Chesapeake Bay, MD, revealed that 52% (116/224) were luminescent when an improved assay method was employed and 58% (130/224) of isolates harbored the luxA gene. In contrast, 334 non-O1/non-O139 V. cholerae strains isolated from two rural provinces in Bangladesh yielded only 21 (6.3%) luminescent and 35 (10.5%) luxA+ isolates. An additional 270 clinical and environmental isolates of V. cholerae serogroups O1 and O139 were tested, and none were luminescent or harbored luxA. These results indicate that bioluminescence may be a trait specific for non-O1/non-O139 V. cholerae strains that frequently occur in certain environments. Luminescence expression patterns of V. cholerae were also investigated, and isolates could be grouped based on expression level. Several strains with defective expression of the lux operon, including natural K variants, were identified. PMID:18065611

  15. Antimicrobial resistance and genetic diversity of the SXT element in Vibrio cholerae from clinical and environmental water samples in northeastern Thailand.

    Science.gov (United States)

    Mala, Wanida; Faksri, Kiatichai; Samerpitak, Kittipan; Yordpratum, Umaporn; Kaewkes, Wanlop; Tattawasart, Unchalee; Chomvarin, Chariya

    2017-08-01

    Multidrug resistance in V. cholerae has been increasing around the world including northeastern Thailand. The aquatic environment is a reservoir of V. cholerae and might be an important source of resistant strains. The aims of this study were to investigate the phylogenetic relationships of intSXT gene sequences from 31 clinical and 14 environmental V. cholerae O1 and non-O1/non-O139 isolates and 11 sequences amplified directly from environmental water samples. We also amplified class 1 integrons, the SXT elements (targeting the intSXT gene) and antimicrobial resistance genes directly from water samples. Phylogenetic analysis displayed two major distinct clusters (clusters 1 and 2). Most V. cholerae O1 (19/20, 95%) and non-O1/non-O139 isolates (8/11, 72.7%) from clinical sources, and all sequences obtained directly from water samples, belonged to cluster 1. Cluster 2 mostly comprised environmental non-O1/non-O139 isolates (10/12, 83.3%). We successfully amplified the SXT elements directly from17.5% of water samples. Associated resistance genes were also amplified as follows: sul2 (41.3% of water samples), dfrA1 (60%), dfr18 (33.8%), strB (70%) and tetA (2.5%). Class 1 integrons were not found in water samples, indicating that the SXT element was the major contributor of multidrug resistance determinants in this region. The SXT element and antimicrobial resistance genes could be transferred from clinical V. cholerae O1 to environmental V. cholerae non-O1/non-O139 was demonstrated by conjugation experiment. These findings indicate that there may have been cross dissemination and horizontal gene transfer (HGT) of the SXT element harbored by V. cholerae O1 and non-O1/non-O139 strains isolated from clinical and environmental water sources. Environmental water might be an important source of antimicrobial resistance genes in V. cholerae in this region. Direct detection of antimicrobial resistance genes in water samples can be used for monitoring the spread of such genes

  16. Genomic and phenotypic characterization of Vibrio cholerae non-O1 isolates from a US Gulf Coast cholera outbreak.

    Science.gov (United States)

    Haley, Bradd J; Choi, Seon Young; Grim, Christopher J; Onifade, Tiffiani J; Cinar, Hediye N; Tall, Ben D; Taviani, Elisa; Hasan, Nur A; Abdullah, Abdulshakur H; Carter, Laurenda; Sahu, Surasri N; Kothary, Mahendra H; Chen, Arlene; Baker, Ron; Hutchinson, Richard; Blackmore, Carina; Cebula, Thomas A; Huq, Anwar; Colwell, Rita R

    2014-01-01

    Between November 2010, and May 2011, eleven cases of cholera, unrelated to a concurrent outbreak on the island of Hispaniola, were recorded, and the causative agent, Vibrio cholerae serogroup O75, was traced to oysters harvested from Apalachicola Bay, Florida. From the 11 diagnosed cases, eight isolates of V. cholerae were isolated and their genomes were sequenced. Genomic analysis demonstrated the presence of a suite of mobile elements previously shown to be involved in the disease process of cholera (ctxAB, VPI-1 and -2, and a VSP-II like variant) and a phylogenomic analysis showed the isolates to be sister taxa to toxigenic V. cholerae V51 serogroup O141, a clinical strain isolated 23 years earlier. Toxigenic V. cholerae O75 has been repeatedly isolated from clinical cases in the southeastern United States and toxigenic V. cholerae O141 isolates have been isolated globally from clinical cases over several decades. Comparative genomics, phenotypic analyses, and a Caenorhabditis elegans model of infection for the isolates were conducted. This analysis coupled with isolation data of V. cholerae O75 and O141 suggests these strains may represent an underappreciated clade of cholera-causing strains responsible for significant disease burden globally.

  17. Genomic and Phenotypic Characterization of Vibrio cholerae Non-O1 Isolates from a US Gulf Coast Cholera Outbreak

    Science.gov (United States)

    Grim, Christopher J.; Onifade, Tiffiani J.; Cinar, Hediye N.; Tall, Ben D.; Taviani, Elisa; Hasan, Nur A.; Abdullah, AbdulShakur H.; Carter, Laurenda; Sahu, Surasri N.; Kothary, Mahendra H.; Chen, Arlene; Baker, Ron; Hutchinson, Richard; Blackmore, Carina; Cebula, Thomas A.; Huq, Anwar; Colwell, Rita R.

    2014-01-01

    Between November 2010, and May 2011, eleven cases of cholera, unrelated to a concurrent outbreak on the island of Hispaniola, were recorded, and the causative agent, Vibrio cholerae serogroup O75, was traced to oysters harvested from Apalachicola Bay, Florida. From the 11 diagnosed cases, eight isolates of V. cholerae were isolated and their genomes were sequenced. Genomic analysis demonstrated the presence of a suite of mobile elements previously shown to be involved in the disease process of cholera (ctxAB, VPI-1 and -2, and a VSP-II like variant) and a phylogenomic analysis showed the isolates to be sister taxa to toxigenic V. cholerae V51 serogroup O141, a clinical strain isolated 23 years earlier. Toxigenic V. cholerae O75 has been repeatedly isolated from clinical cases in the southeastern United States and toxigenic V. cholerae O141 isolates have been isolated globally from clinical cases over several decades. Comparative genomics, phenotypic analyses, and a Caenorhabditis elegans model of infection for the isolates were conducted. This analysis coupled with isolation data of V. cholerae O75 and O141 suggests these strains may represent an underappreciated clade of cholera-causing strains responsible for significant disease burden globally. PMID:24699521

  18. Genomic and phenotypic characterization of Vibrio cholerae non-O1 isolates from a US Gulf Coast cholera outbreak.

    Directory of Open Access Journals (Sweden)

    Bradd J Haley

    Full Text Available Between November 2010, and May 2011, eleven cases of cholera, unrelated to a concurrent outbreak on the island of Hispaniola, were recorded, and the causative agent, Vibrio cholerae serogroup O75, was traced to oysters harvested from Apalachicola Bay, Florida. From the 11 diagnosed cases, eight isolates of V. cholerae were isolated and their genomes were sequenced. Genomic analysis demonstrated the presence of a suite of mobile elements previously shown to be involved in the disease process of cholera (ctxAB, VPI-1 and -2, and a VSP-II like variant and a phylogenomic analysis showed the isolates to be sister taxa to toxigenic V. cholerae V51 serogroup O141, a clinical strain isolated 23 years earlier. Toxigenic V. cholerae O75 has been repeatedly isolated from clinical cases in the southeastern United States and toxigenic V. cholerae O141 isolates have been isolated globally from clinical cases over several decades. Comparative genomics, phenotypic analyses, and a Caenorhabditis elegans model of infection for the isolates were conducted. This analysis coupled with isolation data of V. cholerae O75 and O141 suggests these strains may represent an underappreciated clade of cholera-causing strains responsible for significant disease burden globally.

  19. Purification and partial characterization of a non-O1 Vibrio cholerae hemolysin that cross-reacts with thermostable direct hemolysin of Vibrio parahaemolyticus.

    OpenAIRE

    Yoh, M; Honda, T.; Miwatani, T

    1986-01-01

    A newly identified hemolysin (NAG-rTDH), which is related to the thermostable direct hemolysin (Vp-TDH) of Vibrio parahaemolyticus produced by non-O1 Vibrio cholerae, was studied. NAG-rTDH was purified by successive column chromatographies on DEAE-cellulose and an immunoaffinity column coupled with anti-Vp-TDH immunoglobulin. The molecular weight of NAG-rTDH was estimated as 18,500, similar to that of Vp-TDH, as judged by sodium dodecyl sulfate slab gel electrophoresis, but its charge or mole...

  20. Characterization and Genetic Variation of Vibrio cholerae Isolated from Clinical and Environmental Sources in Thailand.

    Science.gov (United States)

    Siriphap, Achiraya; Leekitcharoenphon, Pimlapas; Kaas, Rolf S; Theethakaew, Chonchanok; Aarestrup, Frank M; Sutheinkul, Orasa; Hendriksen, Rene S

    2017-01-01

    Cholera is still an important public health problem in several countries, including Thailand. In this study, a collection of clinical and environmental V. cholerae serogroup O1, O139, and non-O1/non-O139 strains originating from Thailand (1983 to 2013) was characterized to determine phenotypic and genotypic traits and to investigate the genetic relatedness. Using a combination of conventional methods and whole genome sequencing (WGS), 78 V. cholerae strains were identified. WGS was used to determine the serogroup, biotype, virulence, mobile genetic elements, and antimicrobial resistance genes using online bioinformatics tools. In addition, phenotypic antimicrobial resistance was determined by the minimal inhibitory concentration (MIC) test. The 78 V. cholerae strains belonged to the following serogroups O1: (n = 44), O139 (n = 16) and non-O1/non-O139 (n = 18). Interestingly, we found that the typical El Tor O1 strains were the major cause of clinical cholera during 1983-2000 with two Classical O1 strains detected in 2000. In 2004-2010, the El Tor variant strains revealed genotypes of the Classical biotype possessing either only ctxB or both ctxB and rstR while they harbored tcpA of the El Tor biotype. Thirty O1 and eleven O139 clinical strains carried CTXϕ (Cholera toxin) and tcpA as well four different pathogenic islands (PAIs). Beside non-O1/non-O139, the O1 environmental strains also presented chxA and Type Three Secretion System (TTSS). The in silico MultiLocus Sequence Typing (MLST) discriminated the O1 and O139 clinical strains from other serogroups and environmental strains. ST69 was dominant in the clinical strains belonging to the 7th pandemic clone. Non-O1/non-O139 and environmental strains showed various novel STs indicating genetic variation. Multidrug-resistant (MDR) strains were observed and conferred resistance to ampicillin, azithromycin, nalidixic acid, sulfamethoxazole, tetracycline, and trimethoprim and harboured variants of the SXT elements

  1. Characterization and Genetic Variation of Vibrio cholerae Isolated from Clinical and Environmental Sources in Thailand

    Science.gov (United States)

    Siriphap, Achiraya; Leekitcharoenphon, Pimlapas; Kaas, Rolf S.; Theethakaew, Chonchanok; Aarestrup, Frank M.; Sutheinkul, Orasa; Hendriksen, Rene S.

    2017-01-01

    Cholera is still an important public health problem in several countries, including Thailand. In this study, a collection of clinical and environmental V. cholerae serogroup O1, O139, and non-O1/non-O139 strains originating from Thailand (1983 to 2013) was characterized to determine phenotypic and genotypic traits and to investigate the genetic relatedness. Using a combination of conventional methods and whole genome sequencing (WGS), 78 V. cholerae strains were identified. WGS was used to determine the serogroup, biotype, virulence, mobile genetic elements, and antimicrobial resistance genes using online bioinformatics tools. In addition, phenotypic antimicrobial resistance was determined by the minimal inhibitory concentration (MIC) test. The 78 V. cholerae strains belonged to the following serogroups O1: (n = 44), O139 (n = 16) and non-O1/non-O139 (n = 18). Interestingly, we found that the typical El Tor O1 strains were the major cause of clinical cholera during 1983–2000 with two Classical O1 strains detected in 2000. In 2004–2010, the El Tor variant strains revealed genotypes of the Classical biotype possessing either only ctxB or both ctxB and rstR while they harbored tcpA of the El Tor biotype. Thirty O1 and eleven O139 clinical strains carried CTXϕ (Cholera toxin) and tcpA as well four different pathogenic islands (PAIs). Beside non-O1/non-O139, the O1 environmental strains also presented chxA and Type Three Secretion System (TTSS). The in silico MultiLocus Sequence Typing (MLST) discriminated the O1 and O139 clinical strains from other serogroups and environmental strains. ST69 was dominant in the clinical strains belonging to the 7th pandemic clone. Non-O1/non-O139 and environmental strains showed various novel STs indicating genetic variation. Multidrug-resistant (MDR) strains were observed and conferred resistance to ampicillin, azithromycin, nalidixic acid, sulfamethoxazole, tetracycline, and trimethoprim and harboured variants of the SXT elements

  2. Regulation by ToxR-Like Proteins Converges on vttRB Expression To Control Type 3 Secretion System-Dependent Caco2-BBE Cytotoxicity in Vibrio cholerae

    OpenAIRE

    Miller, Kelly A.; Sofia, Madeline K.; Weaver, Jacob W. A.; Christopher H. Seward; Dziejman, Michelle

    2016-01-01

    Genes carried on the type 3 secretion system (T3SS) pathogenicity island of Vibrio cholerae non-O1/non-O139 serogroup strain AM-19226 must be precisely regulated in order for bacteria to cause disease. Previously reported results showed that both T3SS function and the presence of bile are required to cause Caco2-BBE cell cytotoxicity during coculture with strain AM-19226. We therefore investigated additional parameters affecting in vitro cell death, including bacterial load and the role of th...

  3. Characterization and Nucleotide Sequence of CARB-6, a New Carbenicillin-Hydrolyzing β-Lactamase from Vibrio cholerae

    OpenAIRE

    Choury, Danièle; Aubert, Gérald; Szajnert, Marie-France; Azibi, Kemal; Delpech, Marc; Paul, Gérard

    1999-01-01

    A clinical strain of Vibrio cholerae non-O1 non-O139 isolated in France produced a new β-lactamase with a pI of 5.35. The purified enzyme, with a molecular mass of 33,000 Da, was characterized. Its kinetic constants show it to be a carbenicillin-hydrolyzing enzyme comparable to the five previously reported CARB β-lactamases and to SAR-1, another carbenicillin-hydrolyzing β-lactamase that has a pI of 4.9 and that is produced by a V. cholerae strain from Tanzania. This β-lactamase is designated...

  4. Regulation by ToxR-Like Proteins Converges on vttRB Expression To Control Type 3 Secretion System-Dependent Caco2-BBE Cytotoxicity in Vibrio cholerae

    OpenAIRE

    Miller, Kelly A.; Sofia, Madeline K.; Weaver, Jacob W. A.; Seward, Christopher H.; Dziejman, Michelle

    2016-01-01

    Genes carried on the type 3 secretion system (T3SS) pathogenicity island of Vibrio cholerae non-O1/non-O139 serogroup strain AM-19226 must be precisely regulated in order for bacteria to cause disease. Previously reported results showed that both T3SS function and the presence of bile are required to cause Caco2-BBE cell cytotoxicity during coculture with strain AM-19226. We therefore investigated additional parameters affecting in vitro cell death, including bacterial load and the role of th...

  5. Comparative phenotypic characterization of Vibrio cholerae isolates collected from aquatic environments of Georgia.

    Science.gov (United States)

    Kokashvili, T; Elbakidze, T; Jaiani, E; Janelidze, N; Kamkamidze, G; Whitehouse, C; Huq, A; Tediashvili, M

    2013-11-01

    Vibrio cholerae is ubiquitous in aquatic environment inhabiting marine, fresh and brackish waters. V. cholerae serotypes O1 and O139 cause the devastating diarrheal disease cholera, which is often fatal without proper treatment. Little is known regarding the abundance and diversity of clinically important nonhalophilic vibrios in the South Caucasus region, particularly in Georgia. Here we provide the data on the Georgian environmental strains of V. cholerae isolated in 2006-2009 years from the coastal waters of the Black Sea and inland water reservoirs near Tbilisi. In total, 846 V. cholerae strains were collected from the water samples, most of them (705 strains) obtained from fresh water lakes. Isolation pattern of V. cholerae showed obvious seasonality with the highest isolation rates in late summer - early autumn. Twenty-nine isolates of V. cholerae were attributed to the O1 serotype based on serological studies and PCR identification and were further grouped by biochemical properties into classical and El Tor biotypes as well as hybrids. The study of antibiotic susceptibility profiles for V. cholerae isolates showed that 95% were sensitive to tetracycline, 91% to doxycycline, and 91% to ciprofloxacin. Interestingly, the freshwater isolates appeared to be more resistant to antibiotics than the Black Sea isolates. Among Black Sea isolates of V. cholerae toxigenic strains of O1 serotype revealed higher antibiotic resistance compared to non- O1/non-O139 isolates. In addition, V. cholerae O1 and non- O1/non-O139 isolates differed by phage susceptibility profiles, with higher diversity within the population of environmental non-O1/non-O139 V. cholerae isolates.

  6. Isolation and identification of an atypical non-O1 Vibrio cholerae%1株不典型非O1群霍乱弧菌的发现及鉴定

    Institute of Scientific and Technical Information of China (English)

    吴至成; 覃西; 伍丽娴; 翟英超; 王小娟; 李影林

    2012-01-01

    OBJECTIVE To identify a strain of pathogenic bacterium isolated from the blood of a cirrhotic patient. METHODS The phenotypic characteristics (including morphology, culture characteristics, and biochemical characteristics) and the serologic characteristics were identified according to the standard analytical protocol for Vibrio cholerae, and the 16S rDNA sequence of the isolate was analyzed. RESULTS There was one strain of pathogen (strain HN 9837) which was isolated from the blood of the patient and resembled V. cholerae in its morphological, cultural, biochemical, and serological characters; remarkably, it showed atypical biochemical characteristics such as negative results by tests for mannitol fermentation, lysine decarboxylase and citrate utilization. CONCLUSION It is the first report in Hainan province that non-O1 V. cholerae is isolated from the blood of a cirrhotic patient. The isolate with the following atypical reactions was shown to be V. cholerae: mannitol negative, lysine decarboxylase negative and citrate negative.%目的 对1株从肝硬化患者血液中分离的病原菌进行鉴定.方法 按霍乱弧菌的鉴定标准和方法进行细菌学表型特征(包括形态学、培养特性、生化特征)、血清学鉴定及16S rDNA序列分析.结果 从患者血液中分离获得1株病原菌HN 9837,该菌株的形态学、培养特性、生化特征、血清学诊断和分子生物学诊断结果基本符合非O1群霍乱弧菌定义;但与普通霍乱弧菌在甘露醇发酵及赖氨酸利用、柠檬酸盐利用试验结果存在差异.结论 海南省首次在肝硬化患者血液中分离出非O1群霍乱弧菌,该菌为1株不发酵甘露醇、赖氨酸且柠檬酸盐利用试验阴性的不典型霍乱弧菌.

  7. Vibrio cholerae VttRA and VttRB Regulatory Influences Extend beyond the Type 3 Secretion System Genomic Island

    OpenAIRE

    Chaand, Mudit; Dziejman, Michelle

    2013-01-01

    A subset of non-O1/non-O139 serogroup strains of Vibrio cholerae cause disease using type 3 secretion system (T3SS)-mediated mechanisms. An ∼50-kb genomic island carries genes encoding the T3SS structural apparatus, effector proteins, and two transmembrane transcriptional regulators, VttRA and VttRB, which are ToxR homologues. Previous experiments demonstrated that VttRA and VttRB are necessary for colonization in vivo and promote bile-dependent T3SS gene expression in vitro. To better unders...

  8. Vibrio cholerae VttRA and VttRB Regulatory Influences Extend beyond the Type 3 Secretion System Genomic Island

    OpenAIRE

    Chaand, Mudit; Dziejman, Michelle

    2013-01-01

    A subset of non-O1/non-O139 serogroup strains of Vibrio cholerae cause disease using type 3 secretion system (T3SS)-mediated mechanisms. An ∼50-kb genomic island carries genes encoding the T3SS structural apparatus, effector proteins, and two transmembrane transcriptional regulators, VttRA and VttRB, which are ToxR homologues. Previous experiments demonstrated that VttRA and VttRB are necessary for colonization in vivo and promote bile-dependent T3SS gene expression in vitro. To better unders...

  9. Antimicrobial susceptibility of autochthonous aquatic Vibrio cholerae in Haiti

    Directory of Open Access Journals (Sweden)

    Sandrine BARON

    2016-10-01

    Full Text Available We investigated the antimicrobial susceptibility of 50 environmental isolates of Vibrio cholerae non-O1/non-O139 collected in surface waters in Haiti in July 2012, during an active cholera outbreak. A panel of 16 antibiotics was tested on the isolates using the disk diffusion method and PCR detection of seven resistance-associated genes (strA/B, sul1/2, ermA/B and mefA. All isolates were susceptible to amoxicillin-clavulanic acid, cefotaxime, imipenem, ciprofloxacin, norfloxacin, amikacin and gentamicin. Nearly a quarter (22.0% of the isolates were susceptible to all 16 antimicrobials tested and only 8.0% of the isolates (n=4 were multidrug-resistant. The highest proportions of resistant isolates were observed for sulfonamide (70.0%, amoxicillin (12.0% and trimethoprim-sulfamethoxazole (10.0%. One strain was resistant to erythromycin and one to doxycycline, two antibiotics used to treat cholera in Haiti. Among the 50 isolates, 78% possessed at least two resistance-associated genes, and the genes sul1, ermA and strB were detected in all four multidrug-resistant isolates. Our results clearly indicate that the autochthonous population of V. cholerae non-O1/non-O139 found in surface waters in Haiti shows antimicrobial patterns different from that of the outbreak strain. The presence in the Haitian aquatic environment of V. cholerae non-O1/non-O139 with reduced susceptibility or resistance to antibiotics used in human medicine may constitute a mild public health threat.

  10. Antimicrobial Susceptibility of Autochthonous Aquatic Vibrio cholerae in Haiti

    Science.gov (United States)

    Baron, Sandrine; Lesne, Jean; Jouy, Eric; Larvor, Emeline; Kempf, Isabelle; Boncy, Jacques; Rebaudet, Stanilas; Piarroux, Renaud

    2016-01-01

    We investigated the antimicrobial susceptibility of 50 environmental isolates of Vibrio cholerae non-O1/non-O139 collected in surface waters in Haiti in July 2012, during an active cholera outbreak. A panel of 16 antibiotics was tested on the isolates using the disk diffusion method and PCR detection of seven resistance-associated genes (strA/B, sul1/2, ermA/B, and mefA). All isolates were susceptible to amoxicillin-clavulanic acid, cefotaxime, imipenem, ciprofloxacin, norfloxacin, amikacin, and gentamicin. Nearly a quarter (22.0%) of the isolates were susceptible to all 16 antimicrobials tested and only 8.0% of the isolates (n = 4) were multidrug-resistant. The highest proportions of resistant isolates were observed for sulfonamide (70.0%), amoxicillin (12.0%), and trimethoprim-sulfamethoxazole (10.0%). One strain was resistant to erythromycin and one to doxycycline, two antibiotics used to treat cholera in Haiti. Among the 50 isolates, 78% possessed at least two resistance-associated genes, and the genes sul1, ermA, and strB were detected in all four multidrug-resistant isolates. Our results clearly indicate that the autochthonous population of V. cholerae non-O1/non-O139 found in surface waters in Haiti shows antimicrobial patterns different from that of the outbreak strain. The presence in the Haitian aquatic environment of V. cholerae non-O1/non-O139 with reduced susceptibility or resistance to antibiotics used in human medicine may constitute a mild public health threat. PMID:27818656

  11. Characterization of Vibrio cholerae isolated from the aquatic basins of the State of Pernambuco, Brazil.

    Science.gov (United States)

    Leal, Nilma Cintra; de Araújo Figueiroa, Angela Cristina Torres; Cavalcanti, Valdelúcia Oliveira; da Silva, Soraya Cavalcante; Leal-Balbino, Tereza Cristina; de Almeida, Alzira Maria Paiva; Hofer, Ernesto

    2008-03-01

    Through a continuous bacteriological monitoring programme carried out by the Health Secretariat of the State of Pernambuco, Brazil, two isolates of Vibrio cholerae O1 El Tor Ogawa were discovered in an endemic area in 2001, during a cholera inactive period, along with six V. cholerae non-O1/non-O139 strains and two Aeromonas veronii biovar sobria strains showing an unusual characteristic of agglutination with O1 antiserum. Between that time and 2005, eight other O1 isolates were found. The virulence genes present in the V. cholerae differed among strains, with only three O1 strains harboring the ctxA gene. The O1 and some non-O1/non-O139 strains displayed identical patterns of amplification of the 16S-23S intergenic spacer region. RAPD of the 10 V. cholerae O1 strains, with the two primers used, revealed heterogeneity. The presence of V. cholerae carrying virulence genes in the aquatic basins examined confirms that they constitute a vibrio reservoir during a cholera inactive period, thus strengthening the argument for a continuous monitoring programme and preventative measures for cholera, mainly in the areas where the supply of drinking water is deficient.

  12. Occurrence of Vibrio cholerae in water reservoirs of Burkina Faso.

    Science.gov (United States)

    Kaboré, Saidou; Cecchi, Philippe; Mosser, Thomas; Toubiana, Mylène; Traoré, Oumar; Ouattara, Aboubakar S; Traoré, Alfred S; Barro, Nicolas; Colwell, Rita R; Monfort, Patrick

    2017-09-06

    Africa is currently an important region in which cholera epidemics occur. Little is known about the presence of Vibriocholerae in freshwater bodies in Africa. There are ca. 1700 lakes and reservoirs in Burkina Faso, most of which have been built within recent decades to secure water resources. The purpose of this study was to investigate the presence of V. cholerae in the water of reservoirs, using the most-probable-number polymerase chain reaction. Results showed that V. cholerae could be detected in water samples collected from 14 of 39 sampled reservoirs. The concentrations varied from 0 MPN/l to more than 1100 MPN/l. Fifty strains of V. cholerae isolated on CHROMagar™ vibrio were identified as V. cholerae non-O1/non-O139, none of which carried the ctxA gene. A significant positive correlation was found between the presence of V. cholerae in the reservoirs and both alkaline pH and phytoplankton biomass. V. cholerae was present in significantly higher numbers in reservoirs of urban areas than in rural areas. Since V. cholerae non-O1/non-O139 has been shown to be a causative agent of endemic diarrheal outbreaks, their presence in Burkina Faso reservoirs suggests they may play a role in gastroenteritis in that country. Copyright © 2017 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.

  13. Estudo molecular de Vibrio cholerae não-O1 isolado de zooplâncton da Baía de São Marcos/São Luis - MA, Brasil Molecular study of Vibrio cholerae non-O1 isolated from zooplankton of São Marcos Bay/São Luis - MA, Brasil

    Directory of Open Access Journals (Sweden)

    Eloisa da Graça do Rosario Gonçalves

    2004-08-01

    Full Text Available O estudo foi desenvolvido com o objetivo de analisar o perfil plasmidial, pesquisar genes de virulência e identificar os perfis genéticos de 31 cepas de Vibrio cholerae não O1 isoladas de zooplâncton dos estuários dos rios Anil e Bacanga em São Luis MA. O estudo do DNA plasmidial revelou a presença de 2 a 3 plasmídeos em 10 cepas, com pesos moleculares variando de 5,5 a 40 kilobases. A ribotipagem revelou um perfil comum a todas as cepas. A amplificação do DNA genômico por PCR não revelou os genes ctxA, ace e zot, mostrando tratar-se de cepas não patogênicas, enquanto a RAPD-PCR identificou múltiplos perfis genéticos, achado compatível com o grande potencial de variabilidade desta espécie.The study was developed to analyze the plasmidial DNA, research virulence genes and identify genetic diversity of 31 strains of Vibrio cholerae non-O1 isolated from zooplankton of the Bacanga and Anil rivers in São Luis-MA. The study of plasmidial DNA showed 2 or 3 plasmids from 10 strains between 5.5 and 40 kilobasis. There was only single ribotype pattern. PCR methods did not show the genes ctxA, ace and zot, while RADP-PCR identified genetic diversity in the strains, showing the potential for variability in this species.

  14. The Zymovars of Vibrio cholerae: Multilocus Enzyme Electrophoresis of Vibrio cholerae

    Directory of Open Access Journals (Sweden)

    Fernanda S Freitas

    2002-06-01

    Full Text Available Zymovars analysis also known as multilocus enzyme electrophoresis is applied here to investigate the genetic variation of Vibrio cholerae strains and characterise strains or group of strains of medical and epidemiological interest. Fourteen loci were analyzed in 171 strains of non-O1 non-O139, 32 classical and 61 El Tor from America, Africa, Europe and Asia. The mean genetic diversity was 0.339. It is shown that the same O antigen (both O1 and non-O1 may be present in several geneticaly diverse (different zymovars strains. Conversely the same zymovar may contain more than one serogroup. It is confirmed that the South American epidemic strain differs from the 7th pandemic El Tor strain in locus LAP (leucyl leucyl aminopeptidase. Here it is shown that this rare allele is present in 1 V. mimicus and 4 non-O1 V. cholerae. Non toxigenic O1 strains from South India epidemic share zymovar 14A with the epidemic El Tor from the 7th pandemic, while another group have diverse zymovars. The sucrose negative epidemic strains isolated in French Guiana and Brazil have the same zymovar of the current American epidemic V. cholerae.

  15. 产色素非O1群霍乱弧菌的发现与微生物学研究%Discovery of Ten Strains of Non-O1 V. Cholerae Pigmentogens and Microbiological study

    Institute of Scientific and Technical Information of China (English)

    丁业荣; 贾利君; 时全; 解少煜; 赵本海; 常宏伟; 马振华; 汪军; 杨杰

    2000-01-01

    [目的]研究产色素非O1群霍乱弧菌在水源水中的分布、生物学性状及其致病性.[方法]在本地主要饮用水源设点、采样、培养致病性弧菌.分离、鉴定该菌过程中用营养琼脂斜面代替双糖铁琼脂取得良好效果.[结果]1994~1998年在水源水中相继检出17株产色素的革兰氏阴性弧状菌,经形态学、培养特性、生化学、血清学的系统鉴定,均符合非O1群霍乱弧菌的定义,动物实验等显示其有效强毒力.[结论]因该菌在硷性胆盐琼脂、营养琼脂斜面和血琼脂上培育后能产生水溶性褐色色素,故命名为产色素非O1群霍乱弧菌.

  16. Characterization and genetic variation of vibrio cholerae isolated from clinical and environmental sources in Thailand

    DEFF Research Database (Denmark)

    Siriphap, Achiraya; Leekitcharoenphon, Pimlapas; Kaas, Rolf Sommer

    2017-01-01

    observed and conferred resistance to ampicillin, azithromycin, nalidixic acid, sulfamethoxazole, tetracycline, and trimethoprim and harboured variants of the SXT elements. For the first time since 1986, the presence of V. cholerae O1 Classical was reported causing cholera outbreaks in Thailand. In addition......Cholera is still an important public health problem in several countries, including Thailand. In this study, a collection of clinical and environmental V. cholerae serogroup O1, O139, and non-O1/non-O139 strains originating from Thailand (1983 to 2013) was characterized to determine phenotypic...... and genotypic traits and to investigate the genetic relatedness. Using a combination of conventional methods and whole genome sequencing (WGS), 78 V. cholerae strains were identified. WGS was used to determine the serogroup, biotype, virulence, mobile genetic elements, and antimicrobial resistance genes using...

  17. Molecular epidemiology of Vibrio cholerae associated with flood in Brahamputra River valley, Assam, India.

    Science.gov (United States)

    Bhuyan, Soubhagya K; Vairale, Mohan G; Arya, Neha; Yadav, Priti; Veer, Vijay; Singh, Lokendra; Yadava, Pramod K; Kumar, Pramod

    2016-06-01

    Cholera is often caused when drinking water is contaminated through environmental sources. In recent years, the drastic cholera epidemics in Odisha (2007) and Haiti (2010) were associated with natural disasters (flood and Earthquake). Almost every year the state of Assam India witnesses flood in Brahamputra River valley during reversal of wind system (monsoon). This is often followed by outbreak of diarrheal diseases including cholera. Beside the incidence of cholera outbreaks, there is lack of experimental evidence for prevalence of the bacterium in aquatic environment and its association with cholera during/after flood in the state. A molecular surveillance during 2012-14 was carried out to study prevalence, strain differentiation, and clonality of Vibrio cholerae in inland aquatic reservoirs flooded by Brahamputra River in Assam. Water samples were collected, filtered, enriched in alkaline peptone water followed by selective culturing on thiosulfate bile salt sucrose agar. Environmental isolates were identified as V. cholerae, based on biochemical assays followed by sero-grouping and detailed molecular characterization. The incidence of the presence of the bacterium in potable water sources was higher after flood. Except one O1 isolate, all of the strains were broadly grouped under non-O1/non-O139 whereas some of them did have cholera toxin (CT). Surprisingly, we have noticed Haitian ctxB in two non-O1/non-O139 strains. MLST analyses based on pyrH, recA and rpoA genes revealed clonality in the environmental strains. The isolates showed varying degree of antimicrobial resistance including tetracycline and ciprofloxacin. The strains harbored the genetic elements SXT constins and integrons responsible for multidrug resistance. Genetic characterization is useful as phenotypic characters alone have proven to be unsatisfactory for strain discrimination. An assurance to safe drinking water, sanitation and monitoring of the aquatic reservoirs is of utmost importance for

  18. The Vibrio cholerae Type VI Secretion System: Evaluating Its Role in the Human Disease Cholera

    Directory of Open Access Journals (Sweden)

    Sarah T. Miyata

    2010-11-01

    Full Text Available Vibrio cholerae, the marine bacterium responsible for the diarrheal disease cholera, utilizes a multitude of virulence factors to cause disease. The importance of two of these factors, the toxin co-regulated pilus (TCP and cholera toxin (CT, has been well documented for pandemic O1 and epidemic O139 serogroups. In contrast, endemic non-O1 and non-O139 serogroups can cause localized outbreaks of cholera-like illness, often in the absence of TCP and CT. One virulence mechanism used by these strains is the type VI secretion system (T6SS to export toxins across the cell envelope and confer toxicity towards eukaryotic and prokaryotic organisms. The V. cholerae strain V52 (an O37 serogroup strain possesses a constitutively active T6SS and was responsible for an outbreak of gastroenteritis in Sudan in 1968. To evaluate a potential role of the T6SS in the disease cholera, we compared the T6SS clusters of V. cholerae strains with sequenced genomes. We found that the majority of V. cholerae strains, including one pandemic strain, contain intact T6SS gene clusters; thus, we propose that the T6SS is a conserved mechanism that allows pandemic and endemic V. cholerae to persist both in the host and in the environment.

  19. 疑似霍乱弧菌鉴定及分子分型检测%Characterization and molecular typing of suspected Vibrio cholerae isolates

    Institute of Scientific and Technical Information of China (English)

    陈琛; 王勇; 黄留玉; 李承毅; 宋宏彬; 王中强; 柳楠; 刘雯静; 李婧; 薛文仲; 张伶; 杜昕颖; 邱少富

    2011-01-01

    Objective To identify two suspected Vibrio cholerae isolates from patients with intestinal diseases diagnosed in a hospital in Beijing city and to detect their main virulence genes and analyze their genotypes. Methods The suspected V. cholerae isolates were identified with API 20E strips, serotype and 16S rRNA analysis. PCR was used to detect the distribution of the eight major virulence genes, and the genetic association was measured with pulsed-field gel electrophoresis (PFGE). Results The two suspected V. cholerae isolates were confirmed as non-O1/non-O139 V. cholerae. 16S rRNA analysis showed that the two isolates was 100% homologous to those from NCBI database. Virulence genes hylA ,ompW and toxR were detected. The two strains showed different banding patterns with PFGE. Conclusion The two suspected strains were identified to be non-O1/non-O139 V. cholera and the pathogenic factors may be related to the virulence genes hylA,ompW and toxR. The two strains were distant in evolutionary relationship. The result indicates that different types of non-O1/non-O139 V. cholera exist in the city.%目的 对北京市某医院肠道门诊2株疑似霍乱弧菌进行鉴定,检测其主要毒力基因,并分析其基因型别特征.方法 利用细菌生化鉴定条(API 20 E)进行生化鉴定,玻片凝集法确定其血清型别,应用PCR及测序技术分析其16 S rRNA基因;PCR检测其8个主要毒力基因,脉冲场凝胶电泳(PFGE)分析其基因型别.结果 经鉴定,该2株疑似霍乱菌株均为非O 1非139群霍乱弧菌,经16 S rRNA分析与美国国家生物技术信息中心数据库中霍乱弧菌相似性达100%,均包含毒力基因hylA、ompW和toxR,PFGE结果显示2株菌具有完全不同的带型.结论 2株疑似霍乱弧菌为非O 1非139群霍乱弧菌,其致病因素与(hylA)、(ompW)、(toxR)毒力基因有关,并且2株菌遗传关系较远.

  20. Development and Validation of a Novel Real-time Assay for the Detection and Quantification of Vibrio cholerae.

    Science.gov (United States)

    Rashid, Ridwan Bin; Ferdous, Jannatul; Tulsiani, Suhella; Jensen, Peter Kjaer Mackie; Begum, Anowara

    2017-01-01

    Vibrio cholerae O1 and O139 has been known for its ability to cause epidemics. These strains produce cholera toxin which is the main cause of secretory diarrhea. V. cholerae non-O1 and non-O139 strains are also capable of causing gastroenteritis as well as septicemia and peritonitis. It has been proven that virulence factors such as T6SS, hapA, rtxA, and hlyA are present in almost all V. cholerae strains. It is imperative that viable but non-culturable cells of V. cholerae are also detected since they are also known to cause diarrhea. Thus, the aim of this study was to develop an assay that detects all V. cholerae regardless of their serotype, culturable state, and virulence genes present, by targeting the species specific conserved ompW sequence. The developed assay meets these goals with 100% specificity and is capable of detecting as low as 5.46 copy number of V. cholerae. Detection is rapid since neither lengthy incubation period nor electrophoresis is required. The assay had excellent repeatability (CV%: 0.24-1.32) and remarkable reproducibility (CV%: 1.08-3.7). Amplification efficiencies in the 89-100% range were observed. The assay is more economical than Taqman-based multiplex real-time PCR assays. Compared to other real-time assays, the ompW assay is specific and sensitive, has better repeatability and reproducibility, and is more economical.

  1. Optimization and head-to-head comparison of MISSR-PCR, ERIC-PCR, RAPD and 16S rRNA evolutionary clock for the genotyping of Vibrio cholerae isolated in China.

    Science.gov (United States)

    Mo, Q H; Wang, H B; Tan, H; An, S L; Feng, Z L; Wang, Q; Lin, J C; Yang, Z

    2015-01-01

    To establish a new genotyping method for Vibrio cholerae and compare it with other methods. In the current study, a modified inter simple sequence repeat-polymerase chain reaction (MISSR-PCR) system was developed via several rounds of optimisation. Comparison study was then conducted between MISSR-PCR and three other methods, including enterobacterial repetitive intergenic consensus sequences-based PCR (ERIC-PCR), randomly amplified polymorphic DNA (RAPD) and 16S rRNA evolutionary clock, for the detection and genetic tracing of Vibrio cholerae isolated from seafood in China. The results indicated that the MISSR-PCR system could generate the highest polymorphic fingerprinting map in a single round PCR and showed the best discriminatory ability for Vibrio cholerae genotyping by clearly separating toxigenic/nontoxigenic strains, local/foreign strains, and O1/O139/non-O1/non-O139 serogroup strains, comparing to ERIC-PCR, RAPD and 16S rRNA evolutionary clock. Moreover, the MISSR-PCR is superior to previously described traditional simple sequence repeat based PCR method on genotyping by more clearly separating different clusters. To the best of our knowledge, this is the first head-to-head comparison of four detection and genotyping methods for Vibrio cholerae The MISSR-PCR system established here could serve as a simple, quick, reliable and cost-effective tool for the genotyping and epidemiological study.

  2. Optimization and head-to-head comparison of MISSR-PCR, ERIC-PCR, RAPD and 16S rRNA evolutionary clock for the genotyping of Vibrio cholerae isolated in China

    Directory of Open Access Journals (Sweden)

    Q H Mo

    2015-01-01

    Full Text Available Purpose: To establish a new genotyping method for Vibrio cholerae and compare it with other methods. Materials and Methods: In the current study, a modified inter simple sequence repeat-polymerase chain reaction (MISSR-PCR system was developed via several rounds of optimisation. Comparison study was then conducted between MISSR-PCR and three other methods, including enterobacterial repetitive intergenic consensus sequences-based PCR (ERIC-PCR, randomly amplified polymorphic DNA (RAPD and 16S rRNA evolutionary clock, for the detection and genetic tracing of Vibrio cholerae isolated from seafood in China. Result: The results indicated that the MISSR-PCR system could generate the highest polymorphic fingerprinting map in a single round PCR and showed the best discriminatory ability for Vibrio cholerae genotyping by clearly separating toxigenic/nontoxigenic strains, local/foreign strains, and O1/O139/non-O1/non-O139 serogroup strains, comparing to ERIC-PCR, RAPD and 16S rRNA evolutionary clock. Moreover, the MISSR-PCR is superior to previously described traditional simple sequence repeat based PCR method on genotyping by more clearly separating different clusters. Conclusion: To the best of our knowledge, this is the first head-to-head comparison of four detection and genotyping methods for Vibrio cholerae The MISSR-PCR system established here could serve as a simple, quick, reliable and cost-effective tool for the genotyping and epidemiological study.

  3. Changing patterns of Vibrio cholerae in sevagram between 1990 and 2005.

    Science.gov (United States)

    Narang, P; Mendiratta, D K; Deotale, V S; Narang, R

    2008-01-01

    A retrospective analysis was done to note changes in prevalence, distribution of biotypes, serotypes, antibiotic susceptibility patterns and phage types of Vibrio cholerae isolated in Mahatma Gandhi Institute of Medical Sciences, Sevagram over a period of 16 years. A total of 535 strains of V. cholerae were isolated from 10,406 stool samples and rectal swabs from January 1990 to December 2005. These comprised of serogroups O1 - 427 (79.89%), O139 - 86 (16.07%) and non O1, non O139 - 22 (4.11%). No classical V. cholerae was isolated. Vibrio cholerae serogroup O1 serotype Ogawa was the predominant isolate till 1992. During 1993, serogroup O139 became the main isolate; however, it completely disappeared during 1995-1996 only to reappear in 1997. Serotype Inaba in our area was conspicuous by its absence with only two strains being isolated till June 1999, but during July-December 1999, 11 out of 15 V. cholerae O1 isolates were El Tor Inaba. T4 was the predominant phage type till 1990, T2 during 1991-1994 and T27 (as per the new scheme) thereafter. Resistance to tetracycline varied between 2 and 17% for V. cholerae O1. The paper reports on the changing epidemiological markers of V. cholerae isolated from a rural hospital over a period of 16 years.

  4. Successful small intestine colonization of adult mice by Vibrio cholerae requires ketamine anesthesia and accessory toxins.

    Directory of Open Access Journals (Sweden)

    Verena Olivier

    Full Text Available Vibrio cholerae colonizes the small intestine of adult C57BL/6 mice. In this study, the physical and genetic parameters that facilitate this colonization were investigated. Successful colonization was found to depend upon anesthesia with ketamine-xylazine and neutralization of stomach acid with sodium bicarbonate, but not streptomycin treatment. A variety of common mouse strains were colonized by O1, O139, and non-O1/non-O139 strains. All combinations of mutants in the genes for hemolysin, the multifunctional, autoprocessing RTX toxin (MARTX, and hemagglutinin/protease were assessed, and it was found that hemolysin and MARTX are each sufficient for colonization after a low dose infection. Overall, this study suggests that, after intragastric inoculation, V. cholerae encounters barriers to infection including an acidic environment and an immediate immune response that is circumvented by sodium bicarbonate and the anti-inflammatory effects of ketamine-xylazine. After initial adherence in the small intestine, the bacteria are subjected to additional clearance mechanisms that are evaded by the independent toxic action of hemolysin or MARTX. Once colonization is established, it is suggested that, in humans, these now persisting bacteria initiate synthesis of the major virulence factors to cause cholera disease. This adult mouse model of intestinal V. cholerae infection, now well-characterized and fully optimized, should serve as a valuable tool for studies of pathogenesis and testing vaccine efficacy.

  5. Vibrio cholerae and Vibrio parahaemolyticus detected in seafood products from Senegal.

    Science.gov (United States)

    Coly, Ignace; Sow, Amy Gassama; Seydi, Malang; Martinez-Urtaza, Jaime

    2013-12-01

    The detection of pathogenic Vibrio in seafood from Senegal has generated five food alerts in the European Union. To investigate the presence and abundance Vibrio cholerae and Vibrio parahaemolyticus in seafood and coastal and estuarine waters, 123 seafood samples and 52 water samples were collected during 2007-2009 from two large seafood markets in Dakar, and from different oceanic and estuarine areas of the country. V. parahaemolyticus was detected in 30.1% of seafood samples, whereas presence of V. cholerae was only found in 1.6%. In water samples, V. parahaemolyticus and V. cholerae were detected in 28.8% and 5.7% of the samples, respectively. Abundance of V. parahaemolyticus in seafood from the fishing areas ranged from 110 MPN/g. Densities of V. cholerae in the two positive seafood samples reached values of 0.36 and 0.61 MPN/g, repectively. V. parahaemolyticus strains were found to possess tlh, but not tdh and trh by polymerase chain reaction, and all the strains of V. cholerae were non-O1 or non-O139. These results suggest that the prevalence of high salinities in coastal and estuarine environments of Senegal limits the occurrence of V. parahaemolyticus and V. cholerae, despite warmer temperatures prevailing in seawater environments throughout the year. Furthermore, temperature abuse driven by a deficient cold chain over the distribution and retail sales may represent a major risk due to the postharvest multiplication of these Vibrio pathogens.

  6. Nitrosative Stress Response in Vibrio cholerae: Role of S-Nitrosoglutathione Reductase.

    Science.gov (United States)

    Patra, Sourav Kumar; Bag, Prasanta Kumar; Ghosh, Sanjay

    2017-07-01

    Vibrio cholerae, the causative agent of cholera, poses serious threats to humans worldwide. V. cholerae faces host inflammatory response and encounters nitrosative stress before establishing successful colonization. It is not clear how V. cholerae combats nitric oxide and reactive nitrogen species. In the present study, we used three clinical strains of V. cholerae and tested their nitrosative stress response pattern towards sodium nitroprusside (SNP) and S-Nitrosoglutathione (GSNO). Among them, V. cholerae, belonging to both O1 and O139 serotypes, showed moderate resistance to SNP and GSNO. However, a V. cholerae strain belonging to non O1 and non O139 showed sensitivity to SNP but resistance towards GSNO. Reduced glutathione and glutathione reductase play a significant role to combat nitrosative stress in V. cholerae. This is the first report where we show the presence of GSNO reductase activity in V. cholerae and that it plays an important role to detoxify S-Nitrosoglutathione. GSNO reductase activity of V. cholerae was regulated by posttranslational modification through S-nitrosylation under in vitro conditions which could be reversed by dithiothreitol (DTT). In addition, we show that biofilm formation remained unaffected under nitrosative stress in V. cholerae.

  7. Detection of Vibrio cholerae by isothermal cross-priming amplification combined with nucleic acid detection strip analysis.

    Science.gov (United States)

    Zhang, Xia; Du, Xin-Jun; Guan, Chun; Li, Ping; Zheng, Wen-Jie; Wang, Shuo

    2015-08-01

    Vibrio cholerae is a water- and food-borne human pathogen, and V. cholerae serotypes O1 and O139 have attracted attention because of their severe pathogenesis. However, non-O1, non-O139 cholera vibrios (NCVs) were also recently recognized as having virulence properties. In this study, we developed a cross-priming amplification (CPA) method for the detection of all serotypes of V. cholerae. The specificity of the CPA method was tested using a panel of 60 different bacterial strains. All of the V. cholerae strains showed positive results, and 41 other types of bacteria gave negative results. The limit of detection of the CPA method was 79.28 fg of genomic DNA, 4.2 × 10(2) CFU/ml for bacteria in pure culture, and 5.6 CFU per 25 g of sample with pre-enrichment. This method showed a higher sensitivity than the loop-mediated isothermal amplification (LAMP) method did and was more convenient to perform. These results indicate that the CPA method can be used for the rapid preliminary screening of V. cholerae. Copyright © 2015 Elsevier Ltd. All rights reserved.

  8. Enterobacteria and Vibrio from Macrobrachium amazonicum prawn farming in Fortaleza, Ceará, Brazil

    Institute of Scientific and Technical Information of China (English)

    Manoel de Arajo Neto Paiva; Rossana de Aguiar Cordeiro; Andr Jalles Monteiro; Jos Jlio Costa Sidrim; Marcos Fbio Gadelha Rocha; Jamille Alencar Sales; Glaucia Morgana de Melo Guedes; Yago Brito de Ponte; Clia Maria de Souza Sampaio; Jos Luciano Bezerra Moreira; Lucas Pereira de Alencar

    2016-01-01

    Objective: To investigate the isolation of enterobacteria associated with Macrobrachium amazonicum (M. amazonicum) farming and evaluate the in vitro antimicrobial susceptibility of Vibrio strains. Methods: Strains were isolated from female M. amazonicum prawns and environmental and hatchery water. Biochemical assays were used to identify bacterial genera and those belonging to the genus Vibrio were submitted to further analyses for species identification, through Vitek 2 automated system and serotyping. Susceptibility test was performed according to Clinical Laboratory Standards Institute. Results: The following genera of enterobacteria were recovered: Enterobacter (n=11), Citrobacter (n=10), Proteus (n=2), Serratia (n=2), Kluyvera (n=2), Providencia (n=2), Cedecea (n=1), Escherichia (n=1), Edwardsiella (n=1) and Buttiauxella (n=1). As for Vibrio, three species were identified: Vibrio cholerae non-O1/non-O139 (n=4), Vibrio vulnificus (V. vulnificus) (n=1) and Vibrio mimicus (n=1). Vibrio spp. showed minimum inhibitory concentrations values within the susceptibility range established by Clinical Laboratory Standards Institute for almost all antibiotics, except for V. vulnificus, which presented intermediate profile to ampicillin. Conclusions:Enterobacteria do not seem to be the most important pathogens associated with M. amazonicum farming, whereas the recovery of Vibrio spp. from larviculture, with emphasis on Vibrio cholerae and V. vulnificus, deserves special attention due to their role as potentially zoonotic aquaculture-associated pathogens. Furthermore, the intermediate susceptibility of V. vulnificus to ampicillin reflects the importance of monitoring drug use in prawn farming.

  9. Purification and characterization of cytotoxin produced by a clinical isolate of Vibrio cholerae O54 TV113.

    Science.gov (United States)

    Isac, Sree Renjini; Nair, Gopinath Balakrish; Singh, Durg Vijai

    2012-06-01

    Vibrio cholerae O54 TV113 isolated from a diarrheal patient produces an extracellular cytotoxin that caused alteration in the morphology of Chinese hamster ovary cells manifested as cell shrinkage with intact cell boundaries and finally causing cell death. Syncase medium supplemented with lincomycin (50 μg/ml), pH 7.2, and 18 h incubation with shaking at 37 °C supported optimal cytotoxin production. We isolated and purified this cytotoxin to homogeneity by ultrafiltration, 40-80 % ammonium sulfate precipitation, gradient-anion exchange chromatography, stepwise-anion exchange chromatography, and size exclusion chromatography increasing the specific activity by 866-fold. The cytotoxin is heat-labile, sensitive to protease and papain, and has a molecular weight of 64 kDa determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and enterotoxic activity in rabbit ileal loop assay. Both cytotoxic and enterotoxic activity could be inhibited or neutralized by antiserum raised against purified cytotoxin but not by preimmune serum. Immunodiffusion test between purified cytotoxin and its antiserum gave a single well-defined precipitin band showing reaction of complete identity and a well-defined single band in an immunoblot assay. This study thus indicate that the cytotoxin expressed by strain TV113 has both cytotoxic and enterotoxic activity and appears to contribute in pathogenesis of non-O1, non-O139 strains.

  10. Changing patterns of Vibrio cholerae in sevagram between 1990 and 2005

    Directory of Open Access Journals (Sweden)

    Narang P

    2008-01-01

    Full Text Available Purpose: A retrospective analysis was done to note changes in prevalence, distribution of biotypes, serotypes, antibiotic susceptibility patterns and phage types of Vibrio cholerae isolated in Mahatma Gandhi Institute of Medical Sciences, Sevagram over a period of 16 years. Methods: A total of 535 strains of V. cholerae were isolated from 10,406 stool samples and rectal swabs from January 1990 to December 2005. These comprised of serogroups O1 - 427 (79.89%, O139 - 86 (16.07% and non O1, non O139 - 22 (4.11%. No classical V. cholerae was isolated. Results: Vibrio cholerae serogroup O1 serotype Ogawa was the predominant isolate till 1992. During 1993, serogroup O139 became the main isolate; however, it completely disappeared during 1995-1996 only to reappear in 1997. Serotype Inaba in our area was conspicuous by its absence with only two strains being isolated till June 1999, but during July-December 1999, 11 out of 15 V. cholerae O1 isolates were El Tor Inaba. T4 was the predominant phage type till 1990, T2 during 1991-1994 and T27 (as per the new scheme thereafter. Resistance to tetracycline varied between 2 and 17% for V. cholerae O1. Conclusions: The paper reports on the changing epidemiological markers of V. cholerae isolated from a rural hospital over a period of 16 years.

  11. Bile acid-induced virulence gene expression of Vibrio parahaemolyticus reveals a novel therapeutic potential for bile acid sequestrants.

    Directory of Open Access Journals (Sweden)

    Kazuyoshi Gotoh

    Full Text Available Vibrio parahaemolyticus, a bacterial pathogen, causes human gastroenteritis. A type III secretion system (T3SS2 encoded in pathogenicity island (Vp-PAI is the main contributor to enterotoxicity and expression of Vp-PAI encoded genes is regulated by two transcriptional regulators, VtrA and VtrB. However, a host-derived inducer for the Vp-PAI genes has not been identified. Here, we demonstrate that bile induces production of T3SS2-related proteins under osmotic conditions equivalent to those in the intestinal lumen. We also show that bile induces vtrA-mediated vtrB transcription. Transcriptome analysis of bile-responsive genes revealed that bile strongly induces expression of Vp-PAI genes in a vtrA-dependent manner. The inducing activity of bile was diminished by treatment with bile acid sequestrant cholestyramine. Finally, we demonstrate an in vivo protective effect of cholestyramine on enterotoxicity and show that similar protection is observed in infection with a different type of V. parahaemolyticus or with non-O1/non-O139 V. cholerae strains of vibrios carrying the same kind of T3SS. In summary, these results provide an insight into how bacteria, through the ingenious action of Vp-PAI genes, can take advantage of an otherwise hostile host environment. The results also reveal a new therapeutic potential for widely used bile acid sequestrants in enteric bacterial infections.

  12. Vibrio cholerae laboratory infection of the adult house fly Musca domestica.

    Science.gov (United States)

    El-Bassiony, G M; Luizzi, V; Nguyen, D; Stoffolano, J G; Purdy, A E

    2016-12-01

    The present study was designed to test the hypothesis that house flies may be capable of specifically harbouring ingested Vibrio cholerae in their digestive tracts. Flies were continuously fed green fluorescent protein (GFP)-labelled, non-O1/non-O139 environmental strains of V. cholerae. Bacterial burdens were quantitatively measured using plate counts and localization was directly observed using confocal microscopy. Vibrio cholerae were present in the fly alimentary canal after just 4 h, and reached a plateau of ∼10(7) colony-forming units (CFU)/fly after 5 days in those flies most tolerant of the pathogen. However, individual flies were resistant to the pathogen: one or more flies were found to carry cholerae CFU at each time-point examined. In flies carrying V. cholerae, the pathogen was predominantly localized to the midgut rather than the rectal space or crop. The proportion of house flies carrying V. cholerae in the midgut was dose-dependent: the continuous ingestion of a concentrated, freshly prepared dose of V. cholerae increased the likelihood that fluorescent cells would be observed. However, V. cholerae may be a transient inhabitant of the house fly. This work represents the first demonstration that V. cholerae can inhabit the house fly midgut, and provides a platform for future studies of host, pathogen and environmental mediators of the successful colonization of this disease vector. © 2016 The Royal Entomological Society.

  13. Naturally Occurring IgG Antibodies Provide Innate Protection against Vibrio cholerae Bacteremia by Recognition of the Outer Membrane Protein U.

    Science.gov (United States)

    Aung, Kyaw Min; Sjöström, Annika E; von Pawel-Rammingen, Ulrich; Riesbeck, Kristian; Uhlin, Bernt Eric; Wai, Sun Nyunt

    2016-01-01

    Cholera epidemics are caused by Vibrio cholerae serogroups O1 and O139, whereas strains collectively known as non-O1/non-O139 V. cholerae are found in cases of extraintestinal infections and bacteremia. The mechanisms and factors influencing the occurrence of bacteremia and survival of V. cholerae in normal human serum have remained unclear. We found that naturally occurring IgG recognizing V. cholerae outer membrane protein U (OmpU) mediates a serum-killing effect in a complement C1q-dependent manner. Moreover, outer membrane vesicles (OMVs) containing OmpU caused enhanced survival of highly serum-sensitive classical V. cholerae in a dose-dependent manner. OMVs from wild-type and ompU mutant V. cholerae thereby provided a novel means to verify by extracellular transcomplementation the involvement of OmpU. Our data conclusively indicate that loss, or reduced expression, of OmpU imparts resistance to V. cholerae towards serum killing. We propose that the difference in OmpU protein levels is a plausible reason for differences in serum resistance and the ability to cause bacteremia observed among V. cholerae biotypes. Our findings provide a new perspective on how naturally occurring antibodies, perhaps induced by members of the microbiome, may play a role in the recognition of pathogens and the provocation of innate immune defense against bacteremia. © 2016 The Author(s) Published by S. Karger AG, Basel.

  14. Vibrio cholerae O1 Strains of Different Ribotypes have Similar hlyA RFLP Patterns but Different Vacuolating Ability

    Directory of Open Access Journals (Sweden)

    Jorge E. Vidal

    2007-01-01

    Full Text Available Extensive cytoplasmic vacuolation on Vero and HeLa cells in vitro by the Vibrio cholerae pore forming toxin HlyA, has been previously reported by our group. Vibrio cholerae O1 and non-O1 pathogenic strains show differences in the potential to induce vacuolation, here we study occurring variations on vacuolating cytotoxic ability, related to changes in the nucleotide sequence of the hlyA-orf. A collection of eight toxigenic strains of V. cholerae O1 El Tor and a non-toxigenic one, all belonging to different ribotypes was tested for their vacuolating ability, and hlyA-orf similarity based on PCR and RFLPs. The strains had extremely different vacuolating capacities, those from the ribotype 2 isolated from the US Gulf Coast, showed the highest vacuolating titer (10240 dil, and the rest of the collection had considerably lower titers ranging among 40 to 360 dilutions. PCR of hlyA-orf, was performed and RFLPs were generated using seven restriction enzymes, this approach later revealed small changes of restriction maps, among the strains. The phenogram constructed from the RFLPs, showed two major branches, one of them included most of the strains, the other separates the only Mexican wild type non-O1 Vibrio cholerae. To test for vacuolating ability out of the Vibrio genetic context, the amplified hlyA-orfs from the collection of strains were cloned in pGEMT- vector system and supernatants from the recombinant E coli DH5-, showed no differences on vacuolating titers, the clones always were low producers. Results from the cloning, together with those from the phenogram indicated that the hlyA gene is mainly conserved and the differences on vacuolating activity are unrelated to minute changes seen in the hlyA-orf. Production of high vacuolating titers on Vibrio strains could be due to transcriptional regulation. Whether the high vacuolating titer would be related to increased virulence, is still to be found.

  15. Isolation, characterization, and antibiotic resistance of Vibrio spp. in sea turtles from Northwestern Mexico

    Science.gov (United States)

    Zavala-Norzagaray, Alan A.; Aguirre, A. Alonso; Velazquez-Roman, Jorge; Flores-Villaseñor, Héctor; León-Sicairos, Nidia; Ley-Quiñonez, C. P.; Hernández-Díaz, Lucio De Jesús; Canizalez-Roman, Adrian

    2015-01-01

    The aerobic oral and cloacal bacterial microbiota and their antimicrobial resistance were characterized for 64 apparently healthy sea turtles captured at their foraging grounds in Ojo de Liebre Lagoon (OLL), Baja California Sur (BCS), Mexico (Pacific Ocean) and the lagoon system of Navachiste (LSN) and Marine Area of Influence (MAI), Guasave, Sinaloa (Gulf of California). A total of 34 black turtles (Chelonia mydas agassizii) were sampled in OLL and eight black turtles and 22 olive ridley turtles (Lepidochelys olivacea) were sampled in LSN and MAI, respectively from January to December 2012. We isolated 13 different species of Gram-negative bacteria. The most frequently isolated bacteria were Vibrio alginolyticus in 39/64 (60%), V. parahaemolyticus in 17/64 (26%), and V. cholerae in 6/64 (9%). However, V. cholerae was isolated only from turtles captured from the Gulf of California (MAI). Among V. parahaemolyticus strains, six O serogroups and eight serovars were identified from which 5/17 (29.4%) belonged to the pathogenic strains (tdh+ gene) and 2/17 (11.7%) had the pandemic clone (tdh+ and toxRS/new+). Among V. cholerae strains, all were identified as non-O1/non-O139, and in 4/6 (66%) the accessory cholera enterotoxin gene (ace) was identified but without virulence gene zot, ctxA, and ctxB. Of the isolated V. parahaemolyticus, V. cholerae, and V. alginolyticus strains, 94.1, 33.4, and 100% demonstrated resistance to at least one commonly prescribed antibiotic (primarily to ampicillin), respectively. In conclusion, the presence of several potential (toxigenic) human pathogens in sea turtles may represent transmission of environmental microbes and a high-risk of food-borne disease. Therefore, based on the fact that it is illegal and unhealthy, we discourage the consumption of sea turtle meat or eggs in northwestern Mexico. PMID:26161078

  16. Isolation, characterization, and antibiotic resistance of Vibrio spp. in sea turtles from Northwestern Mexico.

    Science.gov (United States)

    Zavala-Norzagaray, Alan A; Aguirre, A Alonso; Velazquez-Roman, Jorge; Flores-Villaseñor, Héctor; León-Sicairos, Nidia; Ley-Quiñonez, C P; Hernández-Díaz, Lucio De Jesús; Canizalez-Roman, Adrian

    2015-01-01

    The aerobic oral and cloacal bacterial microbiota and their antimicrobial resistance were characterized for 64 apparently healthy sea turtles captured at their foraging grounds in Ojo de Liebre Lagoon (OLL), Baja California Sur (BCS), Mexico (Pacific Ocean) and the lagoon system of Navachiste (LSN) and Marine Area of Influence (MAI), Guasave, Sinaloa (Gulf of California). A total of 34 black turtles (Chelonia mydas agassizii) were sampled in OLL and eight black turtles and 22 olive ridley turtles (Lepidochelys olivacea) were sampled in LSN and MAI, respectively from January to December 2012. We isolated 13 different species of Gram-negative bacteria. The most frequently isolated bacteria were Vibrio alginolyticus in 39/64 (60%), V. parahaemolyticus in 17/64 (26%), and V. cholerae in 6/64 (9%). However, V. cholerae was isolated only from turtles captured from the Gulf of California (MAI). Among V. parahaemolyticus strains, six O serogroups and eight serovars were identified from which 5/17 (29.4%) belonged to the pathogenic strains (tdh (+) gene) and 2/17 (11.7%) had the pandemic clone (tdh (+) and toxRS/new (+)). Among V. cholerae strains, all were identified as non-O1/non-O139, and in 4/6 (66%) the accessory cholera enterotoxin gene (ace) was identified but without virulence gene zot, ctxA, and ctxB. Of the isolated V. parahaemolyticus, V. cholerae, and V. alginolyticus strains, 94.1, 33.4, and 100% demonstrated resistance to at least one commonly prescribed antibiotic (primarily to ampicillin), respectively. In conclusion, the presence of several potential (toxigenic) human pathogens in sea turtles may represent transmission of environmental microbes and a high-risk of food-borne disease. Therefore, based on the fact that it is illegal and unhealthy, we discourage the consumption of sea turtle meat or eggs in northwestern Mexico.

  17. Isolation, Characterization, and Antibiotic Resistance of Vibrio spp. in Sea Turtles from Northwestern Mexico

    Directory of Open Access Journals (Sweden)

    Alan A. eZavala-Norzagaray

    2015-06-01

    Full Text Available The aerobic oral and cloacal bacterial microbiota and their antimicrobial resistance were characterized for 64 apparently healthy sea turtles captured at their foraging grounds in Ojo de Liebre Lagoon (OLL, Baja California Sur, Mexico (Pacific Ocean and the lagoon system of Navachiste (LSN and Marine Area of Influence (MAI, Guasave, Sinaloa (Gulf of California. A total of 34 black turtles (Chelonia mydas agassizii were sampled in OLL and eight black turtles and 22 olive ridley turtles (Lepidochelys olivacea were sampled in LSN and MAI, respectively from January to December 2012. We isolated 13 different species of Gram-negative bacteria. The most frequently isolated bacteria were Vibrio alginolyticus in 39/64 (60%, V. parahaemolyticus in 17/64 (26% and V. cholerae in 6/64 (9%,. However, V. cholerae was isolated only from turtles captured from the Gulf of California (MAI. Among V. parahaemolyticus strains, six O serogroups and eight serovars were identified from which 5/17 (29.4% belonged to the pathogenic strains (tdh+ gene and 2/17 (11.7% had the pandemic clone (tdh+ and toxRS/new+. Among V. cholerae strains, all were identified as non-O1/non-O139, and in 4/6 (66% the accessory cholera enterotoxin gene (ace was identified but without virulence gene zot, ctxA and ctxB. Of the isolated V. parahaemolyticus, V. cholerae and V. alginolyticus strains, 94.1%, 33.4% and 100% demonstrated resistance to at least one commonly prescribed antibiotic (primarily to ampicillin, respectively. In conclusion, the presence of several potential (toxigenic human pathogens in sea turtles may represent transmission of environmental microbes and a high-risk of food-borne disease. Therefore, based on the fact that it is illegal and unhealthy, we discourage the consumption of sea turtle meat or eggs in northwestern Mexico.

  18. Hip flexor strain - aftercare

    Science.gov (United States)

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

  19. Vibrio cholerae strains possess multiple strategies for abiotic and biotic surface colonization.

    Science.gov (United States)

    Mueller, Ryan S; McDougald, Diane; Cusumano, Danielle; Sodhi, Nidhi; Kjelleberg, Staffan; Azam, Farooq; Bartlett, Douglas H

    2007-07-01

    Despite its notoriety as a human pathogen, Vibrio cholerae is an aquatic microbe suited to live in freshwater, estuarine, and marine environments where biofilm formation may provide a selective advantage. Here we report characterization of biofilms formed on abiotic and biotic surfaces by two non-O1/O139 V. cholerae strains, TP and SIO, and by the O1 V. cholerae strain N16961 in addition to the isolation of 44 transposon mutants of SIO and TP impaired in biofilm formation. During the course of characterizing the mutants, 30 loci which have not previously been associated with V. cholerae biofilms were identified. These loci code for proteins which perform a wide variety of functions, including amino acid metabolism, ion transport, and gene regulation. Also, when the plankton colonization abilities of strains N16961, SIO, and TP were examined, each strain showed increased colonization of dead plankton compared with colonization of live plankton (the dinoflagellate Lingulodinium polyedrum and the copepod Tigriopus californicus). Surprisingly, most of the biofilm mutants were not impaired in plankton colonization. Only mutants impaired in motility or chemotaxis showed reduced colonization. These results indicate the presence of both conserved and variable genes which influence the surface colonization properties of different V. cholerae subspecies.

  20. Geobacteraceae strains and methods

    Science.gov (United States)

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

    2015-07-07

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

  1. Molecular Epidemiology and Antibiotic Susceptibility of Vibrio cholerae Associated with a Large Cholera Outbreak in Ghana in 2014.

    Science.gov (United States)

    Eibach, Daniel; Herrera-León, Silvia; Gil, Horacio; Hogan, Benedikt; Ehlkes, Lutz; Adjabeng, Michael; Kreuels, Benno; Nagel, Michael; Opare, David; Fobil, Julius N; May, Jürgen

    2016-05-01

    Ghana is affected by regular cholera epidemics and an annual average of 3,066 cases since 2000. In 2014, Ghana experienced one of its largest cholera outbreaks within a decade with more than 20,000 notified infections. In order to attribute this rise in cases to a newly emerging strain or to multiple simultaneous outbreaks involving multi-clonal strains, outbreak isolates were characterized, subtyped and compared to previous epidemics in 2011 and 2012. Serotypes, biotypes, antibiotic susceptibilities were determined for 92 Vibrio cholerae isolates collected in 2011, 2012 and 2014 from Southern Ghana. For a subgroup of 45 isolates pulsed-field gel electrophoresis, multilocus sequence typing and multilocus-variable tandem repeat analysis (MLVA) were performed. Eighty-nine isolates (97%) were identified as ctxB (classical type) positive V. cholerae O1 biotype El Tor and three (3%) isolates were cholera toxin negative non-O1/non-O139 V. cholerae. Among the selected isolates only sulfamethoxazole/trimethoprim resistance was detectable in 2011, while 95% of all 2014 isolates showed resistance towards sulfamethoxazole/trimethoprim, ampicillin and reduced susceptibility to ciprofloxacin. MLVA achieved the highest subtype discrimination, revealing 22 genotypes with one major outbreak cluster in each of the three outbreak years. Apart from those clusters genetically distant genotypes circulate during each annual epidemic. This analysis suggests different endemic reservoirs of V. cholerae in Ghana with distinct annual outbreak clusters accompanied by the occurrence of genetically distant genotypes. Preventive measures for cholera transmission should focus on aquatic reservoirs. Rapidly emerging multidrug resistance must be monitored closely.

  2. Molecular Epidemiology and Antibiotic Susceptibility of Vibrio cholerae Associated with a Large Cholera Outbreak in Ghana in 2014.

    Directory of Open Access Journals (Sweden)

    Daniel Eibach

    2016-05-01

    Full Text Available Ghana is affected by regular cholera epidemics and an annual average of 3,066 cases since 2000. In 2014, Ghana experienced one of its largest cholera outbreaks within a decade with more than 20,000 notified infections. In order to attribute this rise in cases to a newly emerging strain or to multiple simultaneous outbreaks involving multi-clonal strains, outbreak isolates were characterized, subtyped and compared to previous epidemics in 2011 and 2012.Serotypes, biotypes, antibiotic susceptibilities were determined for 92 Vibrio cholerae isolates collected in 2011, 2012 and 2014 from Southern Ghana. For a subgroup of 45 isolates pulsed-field gel electrophoresis, multilocus sequence typing and multilocus-variable tandem repeat analysis (MLVA were performed. Eighty-nine isolates (97% were identified as ctxB (classical type positive V. cholerae O1 biotype El Tor and three (3% isolates were cholera toxin negative non-O1/non-O139 V. cholerae. Among the selected isolates only sulfamethoxazole/trimethoprim resistance was detectable in 2011, while 95% of all 2014 isolates showed resistance towards sulfamethoxazole/trimethoprim, ampicillin and reduced susceptibility to ciprofloxacin. MLVA achieved the highest subtype discrimination, revealing 22 genotypes with one major outbreak cluster in each of the three outbreak years. Apart from those clusters genetically distant genotypes circulate during each annual epidemic.This analysis suggests different endemic reservoirs of V. cholerae in Ghana with distinct annual outbreak clusters accompanied by the occurrence of genetically distant genotypes. Preventive measures for cholera transmission should focus on aquatic reservoirs. Rapidly emerging multidrug resistance must be monitored closely.

  3. Evidence on How a Conserved Glycine in the Hinge Region of HapR Regulates Its DNA Binding Ability: LESSONS FROM A NATURAL VARIANT.

    Energy Technology Data Exchange (ETDEWEB)

    M Dongre; N Singh; C Dureja; N Peddada; A Solanki; F Ashish; S Raychaudhuri

    2011-12-31

    HapR has been recognized as a quorum-sensing master regulator in Vibrio cholerae. Because it controls a plethora of disparate cellular events, the absence of a functional HapR affects the physiology of V. cholerae to a great extent. In the current study, we pursued an understanding of an observation of a natural protease-deficient non-O1, non-O139 variant V. cholerae strain V2. Intriguingly, a nonfunctional HapR (henceforth designated as HapRV2) harboring a substitution of glycine to aspartate at position 39 of the N-terminal hinge region has been identified. An in vitro gel shift assay clearly suggested the inability of HapRV2 to interact with various cognate promoters. Reinstatement of glycine at position 39 restores DNA binding ability of HapRV2 (HapRV2G), thereby rescuing the protease-negative phenotype of this strain. The elution profile of HapRV2 and HapRV2G proteins in size-exclusion chromatography and their circular dichroism spectra did not reflect any significant differences to explain the functional discrepancies between the two proteins. To gain insight into the structure-function relationship of these two proteins, we acquired small/wide angle x-ray scattering data from samples of the native and G39D mutant. Although Guinier analysis and indirect Fourier transformation of scattering indicated only a slight difference in the shape parameters, structure reconstruction using dummy amino acids concluded that although HapR adopts a 'Y' shape similar to its crystal structure, the G39D mutation in hinge drastically altered the DNA binding domains by bringing them in close proximity. This altered spatial orientation of the helix-turn-helix domains in this natural variant provides the first structural evidence on the functional role of the hinge region in quorum sensing-related DNA-binding regulatory proteins of Vibrio spp.

  4. Characterization and Nucleotide Sequence of CARB-6, a New Carbenicillin-Hydrolyzing β-Lactamase from Vibrio cholerae

    Science.gov (United States)

    Choury, Danièle; Aubert, Gérald; Szajnert, Marie-France; Azibi, Kemal; Delpech, Marc; Paul, Gérard

    1999-01-01

    A clinical strain of Vibrio cholerae non-O1 non-O139 isolated in France produced a new β-lactamase with a pI of 5.35. The purified enzyme, with a molecular mass of 33,000 Da, was characterized. Its kinetic constants show it to be a carbenicillin-hydrolyzing enzyme comparable to the five previously reported CARB β-lactamases and to SAR-1, another carbenicillin-hydrolyzing β-lactamase that has a pI of 4.9 and that is produced by a V. cholerae strain from Tanzania. This β-lactamase is designated CARB-6, and the gene for CARB-6 could not be transferred to Escherichia coli K-12 by conjugation. The nucleotide sequence of the structural gene was determined by direct sequencing of PCR-generated fragments from plasmid DNA with four pairs of primers covering the whole sequence of the reference CARB-3 gene. The gene encodes a 288-amino-acid protein that shares 94% homology with the CARB-1, CARB-2, and CARB-3 enzymes, 93% homology with the Proteus mirabilis N29 enzyme, and 86.5% homology with the CARB-4 enzyme. The sequence of CARB-6 differs from those of CARB-3, CARB-2, CARB-1, N29, and CARB-4 at 15, 16, 17, 19, and 37 amino acid positions, respectively. All these mutations are located in the C-terminal region of the sequence and at the surface of the molecule, according to the crystal structure of the Staphylococcus aureus PC-1 β-lactamase. PMID:9925522

  5. Sprains and Strains

    Science.gov (United States)

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

  6. Muscle strain treatment

    Science.gov (United States)

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

  7. Muscle strain (image)

    Science.gov (United States)

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

  8. 基于随机扩增多态性DNA分析的霍乱弧菌分子分型方法的建立%Establishment of molecular typing method for vibrio cholerae based on randomly amplified polymorphic DNA analysis

    Institute of Scientific and Technical Information of China (English)

    莫秋华; 杨泽; 谭华; 安胜利; 杜坚; 林继灿; 刘志明; 王琪; 涂承宁; 叶立青

    2012-01-01

    Objective To establish a simple and rapid molecular typing method for vibrio cholerae based on randomly amplified polymorphic DNA (RAPD) analysis. Methods A total of 16 representative strains of V. Cholerae, including members of the O1, O139, and non-O1/non O139 serogroups, and a total of 40 random primers were used to develop the RAPD-PCR experiments, in order to screen out the ideal primers by which the obtained DNA fingerprinting patterns must have high polymorphism and sufficient resolving power in molecular typing. Results After a series of RAPD-PCR experiments combined statistical clustering analysis, two most satisfactory primers were selected from the 40 random primers. A finer resolution of the clustering of the toxigenic O1/O139, non-toxigenic O1 and non-O1/non O139 subtypes were obtained by using these two primers in RAPD-PCR for the 16 strains of V. Cholerae. Conclusion In this study, we screened out two ideal random primers and established the corresponding RAPD-based molecular typing method. This method is easy, timesaving and labor-saving, especially suitable for the basic laboratories of CDC and port quarantine departments to perform surveillance and epidemiological traceability of cholera.%目的 建立基于随机扩增多态性DNA分析(Randomly amplified polymorphic DNA,RAPD)的霍乱弧菌简便快速分子分型方法.方法 选择16株霍乱弧菌代表性菌株,包括O1群、O139群和非O1/非O139群等血清群,通过40条随机引物的RAPD-PCR实验,筛选出理想的随机引物,要求其产生的DNA指纹图谱多态性高,并有足够的分辨力进行分子分型.结果 通过一系列RAPD-PCR实验和统计学聚类分析,从40条随机引物中筛选出2条最符合要求的引物.16株霍乱弧菌的分析结果显示,2条引物对于O1群和O139群产毒株、O1群非产毒株和非O1/非O139群均有很好的聚类分辨率.结论 本研究筛选获得了2条随机引物并建立了基于RAPD的分子分型方法,该方法简

  9. Obturator internus muscle strains

    Directory of Open Access Journals (Sweden)

    Caoimhe Byrne, MB BCh, BAO

    2017-03-01

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

  10. A strain gauge

    DEFF Research Database (Denmark)

    2016-01-01

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

  11. Strain y strain rate para dummies

    Directory of Open Access Journals (Sweden)

    Pastor Olaya, MD

    2011-11-01

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

  12. Three dimensional strained semiconductors

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-11-08

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

  13. Strain-engineered MOSFETs

    CERN Document Server

    Maiti, CK

    2012-01-01

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

  14. Sprains and Strains

    Science.gov (United States)

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

  15. Highly Strained Organophosphorus Compounds

    NARCIS (Netherlands)

    Slootweg, J.C.

    2005-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Pastor Olaya

    2011-12-01

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

  17. Hamstring strain - aftercare

    Science.gov (United States)

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

  18. The strained state cosmology

    CERN Document Server

    Tartaglia, Angelo

    2015-01-01

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

  19. Psychological strain between nurses

    Directory of Open Access Journals (Sweden)

    Andrea Obročníková

    2015-12-01

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

  20. Photothermal strain imaging

    Science.gov (United States)

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

    2017-07-01

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

  1. Strain: Fact or Fiction?

    Science.gov (United States)

    Heilbronner, Renée

    2017-04-01

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

  2. Muscle strain injuries.

    Science.gov (United States)

    Garrett, W E

    1996-01-01

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

  3. 进出口水产品中霍乱弧菌的检测与分析%Detection and analysis of Vibrio cholerae from import and export aquatic products

    Institute of Scientific and Technical Information of China (English)

    李正义; 贾俊涛; 梁成珠; 卢丽丽; 姜英辉; 祝素珍; 赵丽青; 房保海; 雷质文

    2011-01-01

    目的 监测并分析进出口水产品中的霍乱弧菌.方法 采用传统两步增菌,平板划线,分离可疑单菌落,VITEK 2 Compact全自动微生物鉴定仪、普通PCR、实时荧光定量PCR和血清凝集试验确认分离菌株.结果 从水产品样品分离的菌株全自动微生物鉴定仪鉴定结果相似度达97%,普通PCR和实时荧光定量PCR检测为霍乱弧菌,ctx毒素基因检测为阴性,血清凝集试验为非O1非O139群霍乱弧菌.结论 从水产品中检出霍乱弧菌非流行株,但仍需要加强主动监测,预防疫情的暴发.%Objective To monitor and analysis Vibrio cholerae from import and export aquatic products. Methods The suspicious single colonies by traditional two step enrichment and flat crossed separation was adopted. After isolation, the suspicious single colonies were identified by VITEK 2 Compact automated microbe identification analyzer, common PCR, real-time PCR and serological tests. Results The probability of the isolated strain was 97% by VITEK 2 Compact automated microbe identification analyzer. It was detected as Vibrio cholera by common PCR and real-time PCR and the primer and fluorescent probe were from industrial standard. The virulence gene ctx in the isolated strain was not : detected by common PCR. It was confirmed as non-O1 and non-O139 Vibrio cholera by serum agglutination test. Conclusion Although one non-epidemic strain of Vibrio chloerae was detected from the monitoring aquatic products, the monitoring work should be strengthened for epidemic prevention.

  4. Well Conductor Strain Monitoring

    Science.gov (United States)

    2014-05-06

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

  5. Strains in General Relativity

    CERN Document Server

    Bini, Donato; Geralico, Andrea

    2014-01-01

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

  6. Detection of Vibrio parahaemolyticus and Vibrio cholerae in oyster, Crassostrea rhizophorae, collected from a natural nursery in the Cocó river estuary, Fortaleza, Ceará, Brazil.

    Science.gov (United States)

    de Sousa, Oscarina Viana; Vieira, Regine Helena Silva dos Fernandes; de Menezes, Francisca Gleire Rodrigues; dos Reis, Christiane Moura Falavina; Hofer, Ernesto

    2004-01-01

    Oysters are edible organisms that are often ingested partially cooked or even raw, presenting therefore a very high risk to the consumers' health, especially in tropical regions. The presence of Vibrio cholerae and Vibrio parahaemolyticus in oysters sampled at an estuary in the Brazilian northeastern region was studied, with 300 oysters tested through an 8-months period. The salinity of the water at the sampling point varied between 3% and 27. V. cholerae was the most frequently detected species (33.3% of the samples), and of the 22 V. cholerae isolates, 20 were identified as non-O1/non-O139, with two of the colonies presenting a rough surface and most of remaining ones belonging to the Heiberg II fermentation group. V. parahaemolyticus was isolated from just one of the samples. Other bacteria such as Providencia spp., Klebsiella spp. and Morganella morganii were also isolated.

  7. Vibrio cholerae in an Historically Cholera-Free Country.

    Science.gov (United States)

    Haley, Bradd J; Chen, Arlene; Grim, Christopher J; Clark, Philip; Diaz, Celia Municio; Taviani, Elisa; Hasan, Nur A; Sancomb, Elizabeth; Elnemr, Wessam Mahmoud; Islam, Muhammad A; Huq, Anwar; Colwell, Rita R; Benediktsdóttir, Eva

    2012-08-01

    We report the autochthonous existence of Vibrio cholerae in coastal waters of Iceland, a geothermally active country where cholera is absent and has never been reported. Seawater, mussel, and macroalgae samples were collected close to and distant from sites where geothermal activity causes a significant increase in water temperature during low tides. V. cholerae was detected only at geothermal-influenced sites during low-tides. None of the V. cholerae isolates encoded cholera toxin (ctxAB) and all were non-O1/non-O139 serogroups. However, all isolates encoded other virulence factors that are associated with cholera as well as extra-intestinal V. cholerae infections. The virulence factors were functional at temperatures of coastal waters of Iceland, suggesting an ecological role. It is noteworthy that V. cholerae was isolated from samples collected at sites distant from anthropogenic influence, supporting the conclusion that V. cholerae is autochthonous to the aquatic environment of Iceland.

  8. Evidence on how a conserved glycine in the hinge region of HapR regulates its DNA binding ability: lessons from a natural variant.

    Science.gov (United States)

    Dongre, Mitesh; Singh, Naorem Santa; Dureja, Chetna; Peddada, Nagesh; Solanki, Ashish K; Ashish; Raychaudhuri, Saumya

    2011-04-29

    HapR has been recognized as a quorum-sensing master regulator in Vibrio cholerae. Because it controls a plethora of disparate cellular events, the absence of a functional HapR affects the physiology of V. cholerae to a great extent. In the current study, we pursued an understanding of an observation of a natural protease-deficient non-O1, non-O139 variant V. cholerae strain V2. Intriguingly, a nonfunctional HapR (henceforth designated as HapR(V2)) harboring a substitution of glycine to aspartate at position 39 of the N-terminal hinge region has been identified. An in vitro gel shift assay clearly suggested the inability of HapR(V2) to interact with various cognate promoters. Reinstatement of glycine at position 39 restores DNA binding ability of HapR(V2) (HapR(V2G)), thereby rescuing the protease-negative phenotype of this strain. The elution profile of HapR(V2) and HapR(V2G) proteins in size-exclusion chromatography and their circular dichroism spectra did not reflect any significant differences to explain the functional discrepancies between the two proteins. To gain insight into the structure-function relationship of these two proteins, we acquired small/wide angle x-ray scattering data from samples of the native and G39D mutant. Although Guinier analysis and indirect Fourier transformation of scattering indicated only a slight difference in the shape parameters, structure reconstruction using dummy amino acids concluded that although HapR adopts a "Y" shape similar to its crystal structure, the G39D mutation in hinge drastically altered the DNA binding domains by bringing them in close proximity. This altered spatial orientation of the helix-turn-helix domains in this natural variant provides the first structural evidence on the functional role of the hinge region in quorum sensing-related DNA-binding regulatory proteins of Vibrio spp.

  9. What Are Sprains and Strains?

    Science.gov (United States)

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

  10. Strain measurement based battery testing

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-05-23

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

  11. A strain gauge

    DEFF Research Database (Denmark)

    2017-01-01

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

  12. Sadovskii vortex in strain

    Science.gov (United States)

    Freilich, Daniel; Llewellyn Smith, Stefan

    2014-11-01

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

  13. Echocardiographic assessment of myocardial strain.

    Science.gov (United States)

    Gorcsan, John; Tanaka, Hidekazu

    2011-09-27

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

  14. Colony Dimorphism in Bradyrhizobium Strains

    Science.gov (United States)

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

    1988-01-01

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

  15. Strain Pattern in Supercooled Liquids

    Science.gov (United States)

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

    2016-11-01

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

  16. Hydrogen production from microbial strains

    Science.gov (United States)

    Harwood, Caroline S; Rey, Federico E

    2012-09-18

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

  17. Evaluation of Strain Hardening Parameters

    Institute of Scientific and Technical Information of China (English)

    DING Zong-hai; Pavel Huml; YANG Wei

    2004-01-01

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

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

    Science.gov (United States)

    Motaal, Abdallah G.; Osman, Nael F.

    2010-03-01

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

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

    CERN Document Server

    Schinazi, Rinaldo B

    2010-01-01

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

  20. Strained graphene Hall bar

    Science.gov (United States)

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

    2017-02-01

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

  1. Residual strains in conduit arteries.

    Science.gov (United States)

    Rachev, A; Greenwald, S E

    2003-05-01

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

  2. High temperature strain measurement with a resistance strain gage

    Science.gov (United States)

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

    1993-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1970-01-01

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

  4. Roll bonding of strained aluminium

    DEFF Research Database (Denmark)

    Staun, Jakob M.

    2003-01-01

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

  5. Roll bonding of strained aluminium

    DEFF Research Database (Denmark)

    Staun, Jakob M.

    2003-01-01

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

  6. Canning Tests on Mushroom Strain

    OpenAIRE

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

    1980-01-01

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

  7. PLASTICITY AND NON-LINEAR ELASTIC STRAINS

    Science.gov (United States)

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

  8. Effective Hamiltonian of strained graphene.

    Science.gov (United States)

    Linnik, T L

    2012-05-23

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

  9. Intergranular strains in textured steel

    Energy Technology Data Exchange (ETDEWEB)

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

    2000-07-01

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

  10. Strain Growth in Containment Vessels

    Institute of Scientific and Technical Information of China (English)

    DONG Q; LI Q M; ZHENG J Y

    2006-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Anita Sadeghpour

    2013-05-01

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

  12. Photoacoustic spectroscopy of Entamoeba histolytica strains

    Science.gov (United States)

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

    2005-06-01

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

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

    Science.gov (United States)

    Rokosz, A; Meisel-Mikołajczyk, F

    1995-01-01

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

  14. Extreme Temperature Strain Measurement System

    Science.gov (United States)

    1990-08-01

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

  15. Asymptomatic bacteriuria Escherichia coli strains

    DEFF Research Database (Denmark)

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

    2006-01-01

    Urinary tract infections (UTIs) affect millions of people each year. Escherichia coli is the most common organism associated with asymptomatic bacteriuria (ABU) in humans. Persons affected by ABU may carry a particular E. coli strain for extended periods of time without any symptoms. In contrast...

  16. Bacteriocins and novel bacterial strains.

    Science.gov (United States)

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

  17. Job strain and alcohol intake

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  18. Asymptomatic bacteriuria Escherichia coli strains

    DEFF Research Database (Denmark)

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

    2006-01-01

    Urinary tract infections (UTIs) affect millions of people each year. Escherichia coli is the most common organism associated with asymptomatic bacteriuria (ABU) in humans. Persons affected by ABU may carry a particular E. coli strain for extended periods of time without any symptoms. In contrast...

  19. Computational strain gradient crystal plasticity

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Kysar, Jeffrey W.

    2014-01-01

    of plane crystal plasticity are studied: pure shear of a single crystal between rigid platens as well as plastic deformation around cylindrical voids in hexagonal close packed and face centered cubic crystals. Effective in-plane constitutive slip parameters for plane strain deformation of specifically...

  20. Job strain and tobacco smoking

    DEFF Research Database (Denmark)

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

    2012-01-01

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

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

    Science.gov (United States)

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

    2007-06-01

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

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

    Science.gov (United States)

    Ellermann, V

    1921-03-31

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

  3. Strains

    Science.gov (United States)

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

  4. Modelling to very high strains

    Science.gov (United States)

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

    2009-04-01

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

  5. Engineering piezoresistivity using biaxially strained silicon

    DEFF Research Database (Denmark)

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

    2008-01-01

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

  6. Beryllium strain under dynamic loading

    Directory of Open Access Journals (Sweden)

    Pushkov Victor

    2015-01-01

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

  7. Strain-Detecting Composite Materials

    Science.gov (United States)

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

    2016-01-01

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

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

    African Journals Online (AJOL)

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

  9. Strain Monitoring of Flexible Structures

    Science.gov (United States)

    Litteken, Douglas A.

    2017-01-01

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

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

    DEFF Research Database (Denmark)

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

    1998-01-01

    Four mAb raised against the Danish Toxoplasma gondii strain 119, were selected by screening hybridoma supernatants by indirect immunofluorescence against tachyzoites of the RH strain in order to obtain strain restricted markers. Strain restriction extended beyond discrimination of the 119 and RH...... strains, as demonstrated on a further six T. gondii reference strains [BK and GT1 (group A), NTE and 561 (group B), and NED and C56 (group C)]. The bradyzoite-specific mAb, 4.3, reacted to the GT1, NTE and 561 strains, but not to the BK, NED or C56 strains. The tachyzoite-specific mAb, 4.25, reacted....... gondii strain collection representative for a small geographic area (Denmark) was established within a short time span from a variety of animal species. Using the mAb as typing reagents to this Danish strain collection, all 36 animal and two human strains were identified as having the same reaction...

  11. EFFECTIVE STRESS AND STRAIN IN FINITE DEFORMATION

    Institute of Scientific and Technical Information of China (English)

    周喆; 秦伶俐; 黄文彬; 王红卫

    2004-01-01

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

  12. Piezoelectric field in strained GaAs.

    Energy Technology Data Exchange (ETDEWEB)

    Chow, Weng Wah; Wieczorek, Sebastian Maciej

    2005-11-01

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

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

    Directory of Open Access Journals (Sweden)

    Dharanesh Gangaiah

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

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

    Directory of Open Access Journals (Sweden)

    Dharanesh Gangaiah

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

  15. Strain Imaging Using Terahertz Waves and Metamaterials

    Science.gov (United States)

    2016-11-01

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

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

    Science.gov (United States)

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

    2007-10-10

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

  17. Spontaneous abortion and physical strain around implantation

    DEFF Research Database (Denmark)

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

    2000-01-01

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

  18. On lower order strain gradient plasticity theories

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Hutchinson, J. W.

    2003-01-01

    the tangent moduli governing increments of stress and strain. It is shown that the modification is far from benign from a mathematical standpoint, changing the qualitative character of solutions and leading to a new type of localization that is at odds with what is expected from a strain gradient theory......By way of numerical examples, this paper explores the nature of solutions to a class of strain gradient plasticity theories that employ conventional stresses, equilibrium equations and boundary conditions. Strain gradients come into play in these modified conventional theories only to alter....... The findings raise questions about the physical acceptability of this class of strain gradient theories....

  19. Spontaneous abortion and physical strain around implantation

    DEFF Research Database (Denmark)

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

    2000-01-01

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

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

    Science.gov (United States)

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

    1984-01-01

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

  1. Enhanced dopant solubility in strained silicon

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-12-22

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

  2. Multiplicative earthquake likelihood models incorporating strain rates

    Science.gov (United States)

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

    2017-01-01

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

  3. Computational Strain Gradient Crystal Plasticity

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Kysar, Jeffrey W.

    2011-01-01

    A model for strain gradient crystal visco-plasticity is formulated along the lines proposed by Fleck andWillis (2009) for isotropic plasticity. Size-effects are included in the model due to the addition of gradient terms in both the free energy as well as through a dissipation potential. A finite...... element solution method is presented, which delivers the slip-rate field and the velocity-field based on two minimum principles. Some plane deformation problems relevant for certain specific orientations of a face centered cubic crystal under plane loading conditions are studied, and effective in......-plane parameters are developed based on the crystallographic properties of the material. The problem of cyclic shear of a single crystal between rigid platens is studied as well as void growth of a cylindrical void....

  4. Determining Micromechanical Strain in Nitinol

    Energy Technology Data Exchange (ETDEWEB)

    Strasberg, Matthew; /SLAC

    2006-09-27

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

  5. Sensor for Measuring Strain in Textile

    Directory of Open Access Journals (Sweden)

    Gerhard Tröster

    2008-06-01

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

  6. Job Strain in Shift and Daytime Workers.

    Science.gov (United States)

    Knutsson; Nilsson

    1997-07-01

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

  7. The many shades of prion strain adaptation.

    Science.gov (United States)

    Baskakov, Ilia V

    2014-01-01

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

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

    DEFF Research Database (Denmark)

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

    1968-01-01

    Fatigue behavior of three SAP alloys of two nominal compositions (7 and 13% Al2O3) was studied in terms of strain rate and temperature at high strains; strain rate had no effect on life at 80 F, but had increasingly greater effect with increasing temperature above 500 F; life decreased with decre......Fatigue behavior of three SAP alloys of two nominal compositions (7 and 13% Al2O3) was studied in terms of strain rate and temperature at high strains; strain rate had no effect on life at 80 F, but had increasingly greater effect with increasing temperature above 500 F; life decreased...

  9. On inhomogeneous straining in compressed sylvinite

    Science.gov (United States)

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

    2010-06-01

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

  10. Dynamic Strain Conductivity of Compensated Silicon

    Science.gov (United States)

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

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

  11. Snowball: Strain aware gene assembly of Metagenomes

    OpenAIRE

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

    2015-01-01

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

  12. Effective heat strain index using pocket computer.

    Science.gov (United States)

    Kamon, E; Ryan, C

    1981-08-01

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

  13. Distributed strain monitoring for bridges: temperature effects

    Science.gov (United States)

    Regier, Ryan; Hoult, Neil A.

    2014-03-01

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

  14. Using strain rates to forecast seismic hazards

    Science.gov (United States)

    Evans, Eileen

    2017-01-01

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

  15. Differentiation of Listeria and Streptococcus strains.

    Science.gov (United States)

    Herendi, A; Ralovich, B

    1989-01-01

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

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

    Science.gov (United States)

    Aksoycan, N

    1980-01-01

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

  17. Measurement of Sorption-Induced Strain

    Energy Technology Data Exchange (ETDEWEB)

    Eric P. Robertson; Richard L. Christiansen

    2005-05-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-05-15

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

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

    Science.gov (United States)

    Kamaya, Masayuki; Kawakubo, Masahiro

    2014-08-01

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

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

    OpenAIRE

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

    2001-01-01

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

  1. A Natural Vaccine Candidate Strain Against Cholera

    Institute of Scientific and Technical Information of China (English)

    LIUYAN-QING; QIGUO-MING; 等

    1995-01-01

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

  2. Job strain and time to pregnancy

    DEFF Research Database (Denmark)

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

    1998-01-01

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

  3. Surfactin production by strains of Bacillus mojavensis

    Science.gov (United States)

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

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

    African Journals Online (AJOL)

    Administrator

    2012-06-26

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

  5. Surface instabilities during straining of anisotropic materials

    DEFF Research Database (Denmark)

    Legarth, Brian Nyvang; Richelsen, Ann Bettina

    2006-01-01

    The development of instabilities in traction-free surfaces is investigated numerically using a unit cell model. Full finite strain analyses are conducted using isotropic as well as anisotropic yield criteria and both plane strain tension and compression are considered. In the load range of tension...

  6. Deformation strain inhomogeneity in columnar grain nickel

    DEFF Research Database (Denmark)

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

    2005-01-01

    A method is presented for determination of the local deformation strain of individual grains in the bulk of a columnar grain sample. The method, based on measurement of the change in grain area of each grain, is applied to 12% cold rolled nickel. Large variations are observed in the local strain...

  7. Strain engineering in graphene by laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-02-09

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

  8. Job strain and time to pregnancy

    DEFF Research Database (Denmark)

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

    1998-01-01

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

  9. Marital Role Strain and Sexual Satisfaction.

    Science.gov (United States)

    Frank, Ellen; And Others

    1979-01-01

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

  10. Snowball: Strain aware gene assembly of Metagenomes

    NARCIS (Netherlands)

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

    2015-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Friedrich, C.M.

    1978-01-01

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

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

    NARCIS (Netherlands)

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

    2014-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-04-15

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

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

    Science.gov (United States)

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

    2008-01-01

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

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

    DEFF Research Database (Denmark)

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

    1968-01-01

    Fatigue behavior of three SAP alloys of two nominal compositions (7 and 13% Al2O3) was studied in terms of strain rate and temperature at high strains; strain rate had no effect on life at 80 F, but had increasingly greater effect with increasing temperature above 500 F; life decreased...

  16. Strain rate effects in stress corrosion cracking

    Energy Technology Data Exchange (ETDEWEB)

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

    1990-03-01

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

  17. Review of graphene-based strain sensors

    Institute of Scientific and Technical Information of China (English)

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

    2013-01-01

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

  18. Pseudomagnetic fields and triaxial strain in graphene

    DEFF Research Database (Denmark)

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

    2016-01-01

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

  19. On lower order strain gradient plasticity theories

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof; Hutchinson, J. W.

    2002-01-01

    By way of numerical examples, this paper explores the nature of solutions to a class of strain gradient plasticity theories that employ conventional stresses, equilibrium equations and boundary conditions. Strain gradients come into play in these modified conventional theories only to alter the t...... the tangential moduli governing increments of stress and strain. It is shown that the modification is far from benign from a mathematical standpoint, changing the qualitative character of solutions and leading to a new type of localization that appears to be unphysical.......By way of numerical examples, this paper explores the nature of solutions to a class of strain gradient plasticity theories that employ conventional stresses, equilibrium equations and boundary conditions. Strain gradients come into play in these modified conventional theories only to alter...

  20. Atlas of stress-strain curves

    CERN Document Server

    2002-01-01

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

  1. Dark field electron holography for strain measurement

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-02-15

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

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

    OpenAIRE

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

    2012-01-01

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

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

    CERN Document Server

    Lazar, Markus

    2016-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Maria G Domínguez-Bello

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-04-01

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

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

    Science.gov (United States)

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

    2012-09-28

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

  7. On fracture in finite strain gradient plasticity

    DEFF Research Database (Denmark)

    Martínez Pañeda, Emilio; Niordson, Christian Frithiof

    2016-01-01

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

  8. Specific identification of Bacillus anthracis strains

    Science.gov (United States)

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

    2007-01-01

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

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

    Science.gov (United States)

    Quintanilla-Terminel, Alejandra; Evans, Brian

    2016-08-01

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

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

    Science.gov (United States)

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

    2015-01-01

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

  11. Stability of germanene under tensile strain

    KAUST Repository

    Kaloni, Thaneshwor P.

    2013-09-01

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

  12. Semiconductor strain metrology principles and applications

    CERN Document Server

    Wong, Terence KS

    2012-01-01

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

  13. Strain gradient effects in surface roughening

    DEFF Research Database (Denmark)

    Borg, Ulrik; Fleck, N.A.

    2007-01-01

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

  14. Biological characterization of Trypanosoma cruzi strains

    Directory of Open Access Journals (Sweden)

    Rafael A Martínez-Díaz

    2001-01-01

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

  15. Ductile Damage Evolution and Strain Path Dependency

    Science.gov (United States)

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

    2007-04-01

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

  16. STRAIN ANALYSIS OF LATERAL EXTRUSION PROCESS

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

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

  17. Differentiation of pathogenic and saprophytic leptospira strains.

    Science.gov (United States)

    Bazovská, S; Kmety, E; Rak, J

    1984-09-01

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

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

    Science.gov (United States)

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

    2013-11-22

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

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

    African Journals Online (AJOL)

    SERVER

    2007-06-18

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

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

    Science.gov (United States)

    ... Feeding Your 1- to 2-Year-Old Broken Bones, Sprains, and Strains KidsHealth > For Parents > Broken Bones, ... home. What to Do: For a Suspected Broken Bone: Do not move a child whose injury involves ...

  1. Energy Harvesting Wireless Strain Networks Project

    Data.gov (United States)

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

  2. Aerosol printed carbon nanotube strain sensor

    Science.gov (United States)

    Thompson, Bradley; Yoon, Hwan-Sik

    2012-04-01

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

  3. Job strain and the risk of stroke

    DEFF Research Database (Denmark)

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

    2015-01-01

    BACKGROUND AND PURPOSE: Psychosocial stress at work has been proposed to be a risk factor for cardiovascular disease. However, its role as a risk factor for stroke is uncertain. METHODS: We conducted an individual-participant-data meta-analysis of 196 380 males and females from 14 European cohort...... studies to investigate the association between job strain, a measure of work-related stress, and incident stroke. RESULTS: In 1.8 million person-years at risk (mean follow-up 9.2 years), 2023 first-time stroke events were recorded. The age- and sex-adjusted hazard ratio for job strain relative to no job....... CONCLUSION: Job strain may be associated with an increased risk of ischemic stroke, but further research is needed to determine whether interventions targeting job strain would reduce stroke risk beyond existing preventive strategies....

  4. Screening of Trichoderma strains tolerant to benzimidazole

    Institute of Scientific and Technical Information of China (English)

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

    2004-01-01

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

  5. 3D Morphing Using Strain Field Interpolation

    Institute of Scientific and Technical Information of China (English)

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

    2007-01-01

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

  6. Five challenges in modelling interacting strain dynamics

    DEFF Research Database (Denmark)

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

    2015-01-01

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

  7. Hospital strain colonization by Staphylococcus epidermidis

    Directory of Open Access Journals (Sweden)

    D. Blum-Menezes

    2009-03-01

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

  8. Feline Origin of Rotavirus Strain, Tunisia, 2008

    Science.gov (United States)

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

    2013-01-01

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

  9. NEW STRAIN GRADIENT THEORY AND ANALYSIS

    Institute of Scientific and Technical Information of China (English)

    Dake Yi; Tzu Chiang Wang; Shaohua Chen

    2009-01-01

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

  10. Digital Eye Strain Reduction Techniques: A Review

    OpenAIRE

    PREETHI J SEEGEHALLI

    2016-01-01

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

  11. A high-strain-rate superplastic ceramic.

    Science.gov (United States)

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

    2001-09-20

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

  12. Strain mapping in a graphene monolayer nanocomposite.

    Science.gov (United States)

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

    2011-04-26

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-01-15

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

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

    Science.gov (United States)

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

    2015-06-01

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

  15. Intramyocardial strain estimation from cardiac cine MRI.

    Science.gov (United States)

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

    2015-08-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-03-01

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

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

    Science.gov (United States)

    Marques dos Santos, Fábio Luis; Peeters, Bart

    2016-10-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-10-15

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

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

    Science.gov (United States)

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

    2016-07-01

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

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

    Science.gov (United States)

    Schmidt, Marvin; Schütze, Andreas; Seelecke, Stefan

    2016-06-01

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

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

    Directory of Open Access Journals (Sweden)

    Marvin Schmidt

    2016-06-01

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

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

    Directory of Open Access Journals (Sweden)

    Shellie Roxanne Bench

    2011-12-01

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

  3. Dynamic strains for earthquake source characterization

    Science.gov (United States)

    Barbour, Andrew J.; Crowell, Brendan W

    2017-01-01

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

  4. Volume strain within the Geysers geothermal field

    Energy Technology Data Exchange (ETDEWEB)

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

    1999-12-10

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

  5. Tensile Strain Hardening Behavior and Fractography of Superalloy GH39

    Directory of Open Access Journals (Sweden)

    WANG Hui

    2016-10-01

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

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

    Science.gov (United States)

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

    2016-12-01

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

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

    Science.gov (United States)

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

    1981-01-01

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

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

    Science.gov (United States)

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

    2012-03-01

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

  9. Genomics of Clostridium botulinum group III strains.

    Science.gov (United States)

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

    2015-05-01

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

  10. Cyclic Strain Enhances Cellular Uptake of Nanoparticles

    Directory of Open Access Journals (Sweden)

    Jia Hu

    2015-01-01

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

  11. Fast flexible electronics with strained silicon nanomembranes.

    Science.gov (United States)

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

    2013-01-01

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

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

    Science.gov (United States)

    Kozuszko, Sylwia; Bogiel, Tomasz; Gospodarek, Eugenia

    2009-01-01

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

  13. [Carbapenem-resistant Acinetobacter baumannii strains].

    Science.gov (United States)

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

    2010-01-01

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

  14. Cyclomodulins in urosepsis strains of Escherichia coli.

    Science.gov (United States)

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

    2010-06-01

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

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

    Directory of Open Access Journals (Sweden)

    Habibollah Dehghan

    2015-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Ekimova N.A.

    2013-03-01

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

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

    NARCIS (Netherlands)

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

    2003-01-01

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

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

    Science.gov (United States)

    Tiwari, Abhishek Kumar; Prasad, Jitendra

    2017-04-01

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

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

    DEFF Research Database (Denmark)

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

    2017-01-01

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

  20. Genetic characterization of measles vaccine strains.

    Science.gov (United States)

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

    2011-07-01

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

  1. Diffraction Correlation to Reconstruct Highly Strained Particles

    Science.gov (United States)

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

    2015-03-01

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

  2. Developments of borehole strain observation outside China

    Institute of Scientific and Technical Information of China (English)

    邱泽华; 石耀霖

    2004-01-01

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

  3. Survival and activity of individual bioaugmentation strains

    DEFF Research Database (Denmark)

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

    2015-01-01

    Successful application of bioaugmentation for enhanced degradation of environmental pollutants is often limited by the lack of methods to monitor the survival and activity of individual bioaugmentation strains. However, recent advancements in sequencing technologies and molecular techniques now...... allow us to address these limitations. Here a complementing set of general applicable molecular methods are presented that provides detailed information on the performance of individual bioaugmentation strains under in situ conditions. The approach involves genome sequencing to establish highly specific...... qPCR and RT-qPCR tools for cell enumerations and expression of involved genes, stable isotope probing to follow growth on the target compounds and GFP-tagging to visualize the bioaugmentation strains directly in samples, all in combination with removal studies of the target compounds. The concept...

  4. High sensitivity knitted fabric strain sensors

    Science.gov (United States)

    Xie, Juan; Long, Hairu; Miao, Menghe

    2016-10-01

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

  5. Nuclear transplantation in different strains of zebrafish

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

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

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

    CERN Document Server

    Lee, HyunSuk

    2012-01-01

    To account for phenomenological theories and a set of invariants, stress and strain are usually decomposed into a pair of pressure and deviatoric stress and a pair of volumetric strain and deviatoric strain. However, the conventional decomposition method only focuses on individual stress and strain, so that cannot be directly applied to either formulation in Finite Element Method (FEM) or Boundary Element Method (BEM). In this paper, a simpler, more general, and widely applicable decomposition is suggested. A new decomposition method adopts multiplying decomposition tensors or matrices to not only stress and strain but also constitutive and compliance relation. With this, we also show its practical usage on FEM and BEM in terms of tensors and matrices.

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

    DEFF Research Database (Denmark)

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

    2006-01-01

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

  8. Genetic Profile of IS1004 among Environmental Vibrio cholerae Isolated from Surface Water Sources in Iran

    Directory of Open Access Journals (Sweden)

    Bita Bakhshi B

    2013-03-01

    Full Text Available AbstractBackground and objective: Vibrio cholerae includes toxigenic and non-toxigenic serotypes. Non O1-non O139 serotypes are non toxigenic and do not have any role in cholera epidemics or pandemics all over the world. Different typing methods are widely used for molecular epidemiological investigations of clinical and environmental V. cholerae. The aim of this study is to investigate the genetic relatedness of environmental isolates of this bacterium using IS1004 profiling as an epidemiological marker. Materials and methods: Environmental samples collected from surface water sources in Tehran and cultured of TCBS agar after filtration. One single colony on TCBS was selected and cultured on BHI agar after which the cultures were used for biochemical diagnostic tests and serogroupings. DNA was isolated and used for PCR confirmation of V. cholerae isolates and wbeT gene. Genetic relatedness of isolates was determined using southern blot analysis. Results: From total 20 environmental V. cholerae identified in this study no wbeT gene was detected for the isolates. A total of 7 different banding patterns were obtained for the isolates while other 13 isolates identified as non-typeable by this method. Comparison with our previous studies indicated no identical pattern with clinical V. cholerae isolates. Conclusion: Differences in the banding pattern of IS1004 revealed a high heterogeneity among the isolates from surface water sources in Iran while these heterogenic isolates do not have any genetic relatedness with clinical isolates.

  9. SURVIVAL, INDUCTION AND RESUSCITATION OF Vibrio cholerae FROM THE VIABLE BUT NON-CULTURABLE STATE IN THE SOUTHERN CARIBBEAN SEA

    Directory of Open Access Journals (Sweden)

    Milagro Fernández-Delgado

    2015-02-01

    Full Text Available The causative agent of cholera, Vibrio cholerae, can enter into a viable but non-culturable (VBNC state in response to unfavorable conditions. The aim of this study was to evaluate the in situ survival of V. cholerae in an aquatic environment of the Southern Caribbean Sea, and its induction and resuscitation from the VBNC state. V. cholerae non-O1, non-O139 was inoculated into diffusion chambers placed at the Cuare Wildlife Refuge, Venezuela, and monitored for plate, total and viable cells counts. At 119 days of exposure to the environment, the colony count was < 10 CFU/mL and a portion of the bacterial population entered the VBNC state. Additionally, the viability decreased two orders of magnitude and morphological changes occurred from rod to coccoid cells. Among the aquatic environmental variables, the salinity had negative correlation with the colony counts in the dry season. Resuscitation studies showed significant recovery of cell cultivability with spent media addition (p < 0.05. These results suggest that V. cholerae can persist in the VBNC state in this Caribbean environment and revert to a cultivable form under favorable conditions. The VBNC state might represent a critical step in cholera transmission in susceptible areas.

  10. Ecological study of pathogenic vibrios in aquatic environments.

    Science.gov (United States)

    Shinoda, Sumio; Furumai, Yuki; Katayama, Sei-Ichi; Mizuno, Tamaki; Miyoshi, Shin-Ichi

    2013-01-01

    An ecological study of pathogenic vibrios in aquatic environments of Okayama was carried out. The number of Vibrio parahaemolyticus detected in the sea area was comparatively smaler than that found in the survey of about two decades ago. Various reasons for the decrease in the case of food poisoning by V. parahaemolyticus have been suggested but the lower number of the vibrio in aquatic environments may be one explanation. Although the number of V. vulnificus was also not as large, most of the isolates possessed the pathogenic genes, vvp and vvh, suggesting the potential for fatal pathogenicity to patients having underlying diseases. As for V. cholerae, some non-O1/non-O139 serovar isolates were detected in a fresh water area, and many of them had hlyA, the gene for hemolysin which acts as a pathogenic factor in sporadic cases of diarrhea. Thus, the total number of pathogenic vibrios detected was not of concern. However, the marine products of these areas are shipped in wide area and are for general consumption. Therefore, it is necessary to continue to survey pathogenic vibrios in aquatic environments in order to ensure food hygiene.

  11. SURVIVAL, INDUCTION AND RESUSCITATION OF Vibrio cholerae FROM THE VIABLE BUT NON-CULTURABLE STATE IN THE SOUTHERN CARIBBEAN SEA

    Science.gov (United States)

    Fernández-Delgado, Milagro; García-Amado, María Alexandra; Contreras, Monica; Incani, Renzo Nino; Chirinos, Humberto; Rojas, Héctor; Suárez, Paula

    2015-01-01

    The causative agent of cholera, Vibrio cholerae, can enter into a viable but non-culturable (VBNC) state in response to unfavorable conditions. The aim of this study was to evaluate the in situ survival of V. cholerae in an aquatic environment of the Southern Caribbean Sea, and its induction and resuscitation from the VBNC state. V. cholerae non-O1, non-O139 was inoculated into diffusion chambers placed at the Cuare Wildlife Refuge, Venezuela, and monitored for plate, total and viable cells counts. At 119 days of exposure to the environment, the colony count was < 10 CFU/mL and a portion of the bacterial population entered the VBNC state. Additionally, the viability decreased two orders of magnitude and morphological changes occurred from rod to coccoid cells. Among the aquatic environmental variables, the salinity had negative correlation with the colony counts in the dry season. Resuscitation studies showed significant recovery of cell cultivability with spent media addition (p < 0.05). These results suggest that V. cholerae can persist in the VBNC state in this Caribbean environment and revert to a cultivable form under favorable conditions. The VBNC state might represent a critical step in cholera transmission in susceptible areas. PMID:25651322

  12. Occurrence of Vibrio and Salmonella species in mussels (Mytilus galloprovincialis) collected along the Moroccan Atlantic coast.

    Science.gov (United States)

    Mannas, Hasna; Mimouni, Rachida; Chaouqy, Noureddine; Hamadi, Fatima; Martinez-Urtaza, Jaime

    2014-01-01

    This study reports the occurrence of different Vibrio and Salmonella species in 52 samples of Mytilus galloprovincialis collected from four sites along the Atlantic coast between Agadir and Essaouira (Anza, Cap Ghir, Imssouane and Essaouira). The level of Escherichia coli (E. coli) was also determined to evaluate the degree of microbial pollution in the investigated areas. In this study three methods were used : AFNOR NF EN ISO 6579 V08-013 for Salmonella spp., the provisional method routinely used by several laboratories (Institut Pasteur, Paris,…) for Vibrio cholerae and Vibrio parahaemolyticus in the seafood, and the most probable number method (MPN) using Norm ISO/TS 16649-3 (2005) for E. coli. The most frequently isolated Vibrios were Vibrio alginolyticus (90.4% of samples), followed by V. cholerae non O1 non O139 (15.4%) and V. parahaemolyticus (7.7%). Salmonella spp. was found in 15% of the samples. The number of E. coli ranged between 0.2/100 g and 1.8 10(3) /100 g of mussel soft tissues. This study indicates the potential sanitary risk associated with the presence of pathogenic bacteria in cultivated mussels in the two populous regions of southern Morocco, where shellfish production and maritime tourism are important to the local economy.

  13. Genome organization of epidemic Acinetobacter baumannii strains

    Directory of Open Access Journals (Sweden)

    Triassi Maria

    2011-10-01

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

  14. Pheromonal divergence between two strains of Spodoptera frugiperda

    NARCIS (Netherlands)

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

    2013-01-01

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

  15. Ciprofloxacin susceptibility reduction of Salmonella strains isolated from outbreaks

    Directory of Open Access Journals (Sweden)

    Roberta B. Souza

    2010-06-01

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

  16. MM98.57 Quantification of Combined Strain Paths

    DEFF Research Database (Denmark)

    Nielsen, Morten Sturgård; Wanheim, Tarras

    1998-01-01

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

  17. Manipulation of electronic structure in WSe2 monolayer by strain

    Science.gov (United States)

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

    2016-11-01

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

  18. Dynamic strain aging in magnesium oxide single crystals

    Science.gov (United States)

    Srinivasan, M.; Stoebe, T. G.

    1973-01-01

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

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

    Science.gov (United States)

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

    2017-09-01

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

  20. ANISOTROPIC STRAIN-HARDENING IN POLYCRYSTALLINE COPPER AND ALUMINUM

    NARCIS (Netherlands)

    HESS, F

    1993-01-01

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

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

    NARCIS (Netherlands)

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

    2013-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Fan Yanhua

    2006-06-01

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

  3. High Strain Rate Characterisation of Composite Materials

    DEFF Research Database (Denmark)

    Eriksen, Rasmus Normann Wilken

    The high strain rate characterisation of FRP materials present the experimenter with a new set of challenges in obtaining valid experimental data. These challenges were addressed in this work with basis in classic wave theory. The stress equilibrium process for linear elastic materials, as fibre...... a linear elastic specimen to reach a state of constant strain rate before fracture. This was in contrast to ductile materials, which are widely tested with for the High-speed servohydraulic test machine. The development of the analysis and the interpretation of the results, were based on the experience...

  4. Cells as strain-cued automata

    Science.gov (United States)

    Cox, Brian N.; Snead, Malcolm L.

    2016-02-01

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

  5. Tensile strain mapping in flat germanium membranes

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-04-28

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

  6. Atmospheric corrosion sensor based on strain measurement

    Science.gov (United States)

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

    2017-01-01

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

  7. Propagating edge states in strained honeycomb lattices

    Science.gov (United States)

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

    2017-06-01

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

  8. Unsteady Aerodynamic Force Sensing from Strain Data

    Science.gov (United States)

    Pak, Chan-Gi

    2017-01-01

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

  9. Tensile Properties of TWIP Steel at High Strain Rate

    Institute of Scientific and Technical Information of China (English)

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

    2009-01-01

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

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

    Science.gov (United States)

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

    2014-01-01

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

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

    Science.gov (United States)

    Rush, M C

    1970-07-01

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

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

    Science.gov (United States)

    Jeong, Haeyoung

    2017-01-01

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

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

    Science.gov (United States)

    Yang, Y; Chan, Albert P C

    2015-02-01

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

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

    Science.gov (United States)

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

    2017-09-01

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

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

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

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

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

    Science.gov (United States)

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

    2011-02-01

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

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

    Directory of Open Access Journals (Sweden)

    Parisa Shokryazdan

    2014-01-01

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

  18. Effective stress coefficient for uniaxial strain condition

    DEFF Research Database (Denmark)

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

    2012-01-01

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

  19. Charge and Strain Control of Interface Magnetism

    Science.gov (United States)

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

    2015-03-01

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

  20. Strain Analysis of the de Mattia Test

    Directory of Open Access Journals (Sweden)

    Reiter M.

    2010-06-01

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

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

    African Journals Online (AJOL)

    SERVER

    2008-03-18

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

  2. Photoacclimation of cultured strains of the cyanobacterium

    NARCIS (Netherlands)

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

    2013-01-01

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

  3. A novel limiting strain energy strength theory

    Institute of Scientific and Technical Information of China (English)

    LIU Guang-lian

    2009-01-01

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

  4. Photonic skin for pressure and strain sensing

    Science.gov (United States)

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

    2010-04-01

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

  5. Storage features of Lactobacillus Brevis strain 9

    Directory of Open Access Journals (Sweden)

    Utemurat Sagyndykov

    2013-03-01

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

  6. High strain rate behaviour of polypropylene microfoams

    Science.gov (United States)

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

    2012-08-01

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

  7. Optical Hall effect in strained graphene

    Science.gov (United States)

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

    2017-06-01

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

  8. Genomic comparison of Kingella kingae strains.

    Science.gov (United States)

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

    2012-11-01

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

  9. Thermal strain analysis of optic fiber sensors.

    Science.gov (United States)

    Her, Shiuh-Chuan; Huang, Chih-Ying

    2013-01-31

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

  10. Prediction of swelling rocks strain in tunneling

    Science.gov (United States)

    Parsapour, D.; Fahimifar, A.

    2016-05-01

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

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

    Science.gov (United States)

    Kaczmarek, Nancy

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

  12. Strain relief for power-cable connectors

    Science.gov (United States)

    Dean, W. T., III

    1980-01-01

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

  13. Strain Measurement Technology for Corrosion Fatigue Specimen

    Institute of Scientific and Technical Information of China (English)

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

    2015-01-01

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

  14. Antimicrobial resistance among Brazilian Corynebacterium diphtheriae strains

    Directory of Open Access Journals (Sweden)

    Gabriela Andrade Pereira

    2008-08-01

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

  15. High strain rate behaviour of polypropylene microfoams

    Directory of Open Access Journals (Sweden)

    Martínez A.B.

    2012-08-01

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

  16. Characterizing large strain crush response of redwood

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-12-01

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

  17. Measuring physical strain during ambulation with accelerometry

    NARCIS (Netherlands)

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

    2000-01-01

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

  18. Development of Industrial Yeast Platform Strains

    DEFF Research Database (Denmark)

    Bergdahl, Basti; Dato, Laura; Förster, Jochen

    2014-01-01

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

  19. Silicon Germanium Strained Layers and Heterostructures

    Science.gov (United States)

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

    2004-01-01

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

  20. On strain and stress in living cells

    Science.gov (United States)

    Cox, Brian N.; Smith, David W.

    2014-11-01

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

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

    Directory of Open Access Journals (Sweden)

    Oana Mirea

    2016-04-01

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

  2. Strain rate effects for spallation of concrete

    Directory of Open Access Journals (Sweden)

    Häussler-Combe Ulrich

    2015-01-01

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

  3. Pheromonal divergence between two strains of Spodoptera frugiperda.

    Science.gov (United States)

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

    2013-03-01

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

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

    DEFF Research Database (Denmark)

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

    2008-01-01

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

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

    Directory of Open Access Journals (Sweden)

    A. Traversa

    2010-03-01

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

  6. Influences of misfit strains on liquid phase heteroepitaxial growth

    Science.gov (United States)

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

    2017-10-01

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

  7. The evolution of strain path in cold wire drawing

    Science.gov (United States)

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

    2013-05-01

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

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

    Directory of Open Access Journals (Sweden)

    Zorica Radulović

    2010-06-01

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

  9. Spacecraft Dynamic Characterization by Strain Energies Method

    Science.gov (United States)

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

    2002-01-01

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

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

    Science.gov (United States)

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

    2014-05-01

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

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

    NARCIS (Netherlands)

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

    2000-01-01

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

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

    Science.gov (United States)

    Kaufman, Joanne M

    2009-09-01

    This paper expands and builds on newer avenues in research on gender and general strain theory (GST). I accomplish this by focusing on serious strains that are relevant for males and females, including externalizing and internalizing forms of negative emotions, and including multiple gendered deviant outcomes. Using the Add Health dataset, I find strong support for the impact of serious strains on both types of negative emotions and different forms of deviance for males and females. However, the experience of serious strain, emotionally and behaviorally, is gendered. Depressive symptoms are particularly important for all types of deviance by females. Including multiple types of deviant outcomes offers a fuller understanding of both similarities and differences by gender. These results support the utility of GST as a theory of deviance in general and support greater connections between GST, feminist theorizing, and the sociology of mental health.

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

    DEFF Research Database (Denmark)

    Janezic, Sandra; Zidaric, Valerija; Pardon, Bart

    2014-01-01

    Background: Clostridium difficile is an important cause of intestinal infections in some animal species and animals might be a reservoir for community associated human infections. Here we describe a collection of animal associated C. difficile strains from 12 countries based on inclusion criteria...... of one strain (PCR ribotype) per animal species per laboratory. Results: Altogether 112 isolates were collected and distributed into 38 PCR ribotypes with agarose based approach and 50 PCR ribotypes with sequencer based approach. Four PCR ribotypes were most prevalent in terms of number of isolates...... animal associated C. difficile strains worldwide. The widespread dissemination of toxigenic C. difficile and the considerable overlap in strain distribution between species furthers concerns about interspecies, including zoonotic, transmission of this critically important pathogen....

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

    NARCIS (Netherlands)

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

    2000-01-01

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

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Science.gov (United States)

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

    2016-01-01

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

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

    NARCIS (Netherlands)

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

    2000-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Moriah L Szpara

    2011-10-01

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

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

    Science.gov (United States)

    Lei, Jih-Fen

    1992-01-01

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

  20. Generating strain signals under consideration of road surface profiles

    Science.gov (United States)

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

    2015-08-01

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

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

    KAUST Repository

    Kaloni, Thaneshwor P.

    2013-03-11

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

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

    Science.gov (United States)

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

    2013-05-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1958-08-29

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-10-23

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

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

    Science.gov (United States)

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

    1998-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-05-15

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

  7. Ion beam studies in strained layer superlattices

    CERN Document Server

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

    2002-01-01

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

  8. SNIT: SNP identification for strain typing

    Directory of Open Access Journals (Sweden)

    Reifman Jaques

    2011-09-01

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

  9. Chaotic desynchronization of multi-strain diseases

    CERN Document Server

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

    2005-01-01

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

  10. Modulating thermal conduction by the axial strain

    Science.gov (United States)

    Jiang, Jianjun; Zhao, Hong

    2016-09-01

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

  11. Transfer induced compressive strain in graphene

    DEFF Research Database (Denmark)

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

    2014-01-01

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

  12. A tunable strain sensor using nanogranular metals.

    Science.gov (United States)

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

    2010-01-01

    This paper introduces a new methodology for the fabrication of strain-sensor elements for MEMS and NEMS applications based on the tunneling effect in nano-granular metals. The strain-sensor elements are prepared by the maskless lithography technique of focused electron-beam-induced deposition (FEBID) employing the precursor trimethylmethylcyclopentadienyl platinum [MeCpPt(Me)(3)]. We use a cantilever-based deflection technique to determine the sensitivity (gauge factor) of the sensor element. We find that its sensitivity depends on the electrical conductivity and can be continuously tuned, either by the thickness of the deposit or by electron-beam irradiation leading to a distinct maximum in the sensitivity. This maximum finds a theoretical rationale in recent advances in the understanding of electronic charge transport in nano-granular metals.

  13. A Tunable Strain Sensor Using Nanogranular Metals

    Directory of Open Access Journals (Sweden)

    Friedemann Völklein

    2010-11-01

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

  14. A Tunable Strain Sensor Using Nanogranular Metals

    Science.gov (United States)

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

    2010-01-01

    This paper introduces a new methodology for the fabrication of strain-sensor elements for MEMS and NEMS applications based on the tunneling effect in nano-granular metals. The strain-sensor elements are prepared by the maskless lithography technique of focused electron-beam-induced deposition (FEBID) employing the precursor trimethylmethylcyclopentadienyl platinum [MeCpPt(Me)3]. We use a cantilever-based deflection technique to determine the sensitivity (gauge factor) of the sensor element. We find that its sensitivity depends on the electrical conductivity and can be continuously tuned, either by the thickness of the deposit or by electron-beam irradiation leading to a distinct maximum in the sensitivity. This maximum finds a theoretical rationale in recent advances in the understanding of electronic charge transport in nano-granular metals. PMID:22163443

  15. Relation between job strain and myocardial infarction

    DEFF Research Database (Denmark)

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

    1999-01-01

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

  16. Organic chemistry. Strain-release amination.

    Science.gov (United States)

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

    2016-01-15

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

  17. Magnetic properties on strained manganite thin film

    Science.gov (United States)

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

    2014-04-01

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

  18. Dynamic strain aging in Haynes 282 superalloy

    Directory of Open Access Journals (Sweden)

    Hörnqvist Magnus

    2014-01-01

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

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

    Science.gov (United States)

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

    2017-02-01

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

  20. Systems strategies for developing industrial microbial strains

    DEFF Research Database (Denmark)

    Lee, Sang Yup; Kim, Hyun Uk

    2015-01-01

    Industrial strain development requires system-wide engineering and optimization of cellular metabolism while considering industrially relevant fermentation and recovery processes. It can be conceptualized as several strategies, which may be implemented in an iterative fashion and in different...... performance under industrial fermentation conditions. These challenges can be overcome by taking systems approaches through the use of state-of-the-art tools of systems biology, synthetic biology and evolutionary engineering in the context of industrial bioprocess. Major systems metabolic engineering...

  1. Strain-specific chemotaxis of Azospirillum spp.

    OpenAIRE

    Reinhold, B; Hurek, T; Fendrik, I

    1985-01-01

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

  2. Cyclic Strain Enhances Cellular Uptake of Nanoparticles

    OpenAIRE

    Jia Hu; Yaling Liu

    2015-01-01

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

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

    Science.gov (United States)

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

    2007-05-01

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

  4. PNNL Stress/Strain Correlation for Zircaloy

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-07-18

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

  5. Achebe, Conrad, and the Postcolonial Strain

    OpenAIRE

    2008-01-01

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

  6. Quasi-bound states in strained graphene

    Science.gov (United States)

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

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

  7. Models for elastic shells with incompatible strains

    OpenAIRE

    2012-01-01

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

  8. Plane strain problem in microstretch elastic solid

    Indian Academy of Sciences (India)

    Rajneesh Kumar; Ranjit Singh; T K Chadha

    2003-12-01

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

  9. Characterization of urinary Escherichia coli O75 strains.

    Science.gov (United States)

    Nimmich, W; Voigt, W; Seltmann, G

    1997-01-01

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

  10. Integrated strain array for cellular mechanobiology studies

    Science.gov (United States)

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

    2011-05-01

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

  11. MACROSCOPIC STRAIN POTENTIALS IN NONLINEAR POROUS MATERIALS

    Institute of Scientific and Technical Information of China (English)

    刘熠; 黄筑平

    2003-01-01

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

  12. STRESS AND STRAIN ANALYSIS AROUND UNDERGROUND ROOM

    Directory of Open Access Journals (Sweden)

    Krešimir Tor

    2000-12-01

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

  13. Dislocation Multi-junctions and Strain Hardening

    Energy Technology Data Exchange (ETDEWEB)

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

    2006-06-20

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

  14. Mycotoxin-degradation profile of Rhodococcus strains.

    Science.gov (United States)

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

    2013-08-16

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

  15. Cylindrical shell buckling through strain hardening

    Energy Technology Data Exchange (ETDEWEB)

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

    1995-04-01

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

  16. Strain Functionals for Characterizing Atomistic Geometries

    Science.gov (United States)

    Kober, Edward; Rudin, Sven

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

  17. Sorbitol production using recombinant Zymomonas mobilis strain.

    Science.gov (United States)

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

    2010-07-20

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

  18. Enterobacter Strains Might Promote Colon Cancer.

    Science.gov (United States)

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

    2015-09-01

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

  19. Shewanella strain isolated from black powder

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-07-01

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

  20. Techniques for increasing boron fiber fracture strain

    Science.gov (United States)

    Dicarlo, J. A.

    1977-01-01

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

  1. The adhesion two strains of Lactic bacillus to the skin and enteron mucus of Flounder and the inhibitory adhesion to four strains of pathogenic bacteria%2种乳酸菌对牙鲆体表、消化道粘液粘附及对4种致病菌的粘附抑制性

    Institute of Scientific and Technical Information of China (English)

    王斌; 邵占涛; 陈营; 王福强; 穆永军; 隋波

    2005-01-01

    目的研究2株乳酸菌(L1来自牙鲆肠道, L2为干酪乳杆菌)在牙鲆体表和消化道粘液的粘附及其对4种致病菌的粘附抑制情况.方法用异硫氰酸荧光素(FITC)标记法.结果 2种乳酸菌在牙鲆体表和消化道粘液中均有粘附性.在胃的粘附效果最好,粘附百分率分别是48.18%和63.0%,L2在牙鲆体表、盲囊和肠的粘附能力强于L1.L1对白色念珠菌(Candida albicans)在各部位均无粘附抑制作用,对荧光假单胞菌(P. Fluorescens)粘附抑制作用最强,使其在牙鲆消化道粘液的粘附百分率下降了19.01%,其余依次为非O1型霍乱弧菌(V. cholerae non-O1 strains)、嗜水气单胞菌(Aeromonas hydrophila),分别降低了5.22%、3.22%; L2对非O1型霍乱弧菌粘附抑制效果最强,使其粘附百分率降低了22.31%.使荧光假单胞菌、嗜水气单胞菌和白色念珠菌分别下降了17.50%、12.69%、5.15%.结论对4种常见致病菌的粘附抑制在消化道粘液中好于体表.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-09-01

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

  3. Spatial Compressive Sensing for Strain Data Reconstruction from Sparse Sensors

    Science.gov (United States)

    2014-10-01

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

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

    Science.gov (United States)

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

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

    Directory of Open Access Journals (Sweden)

    Carolyn Graybeal

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

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

    Science.gov (United States)

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

    2014-01-01

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

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

    Institute of Scientific and Technical Information of China (English)

    Peng HE; Jiuhai ZHANG; Toshio Terasaki; Testuya Akiyama

    2001-01-01

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

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

    KAUST Repository

    Tahini, H. A.

    2012-04-17

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

  9. EVALUATION OF LOCAL STRAIN EVOLUTION FROM METALLIC WHISKER FORMATION

    Energy Technology Data Exchange (ETDEWEB)

    Hoffman, E.; Lam, P.

    2011-05-11

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

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

    Science.gov (United States)

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

    2014-05-01

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

  11. Flexible Bond Wire Capacitive Strain Sensor for Vehicle Tyres

    Directory of Open Access Journals (Sweden)

    Siyang Cao

    2016-06-01

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

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

    Institute of Scientific and Technical Information of China (English)

    Pankaj Aggarwal; Shakti Chauhan

    2013-01-01

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

  13. Corrosion induced strain monitoring through fibre optic sensors

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-10-15

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

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

    Science.gov (United States)

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

    2016-01-01

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

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

    NARCIS (Netherlands)

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

    2014-01-01

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

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

    DEFF Research Database (Denmark)

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

    2001-01-01

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

  17. MM98.83 Quantification of Combined Strain Paths

    DEFF Research Database (Denmark)

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

    1998-01-01

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

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

    African Journals Online (AJOL)

    TUOYO

    2010-08-09

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

  19. Antimalarial effect of agmatine on Plasmodium berghei K173 strain

    Institute of Scientific and Technical Information of China (English)

    SURui-Bin; WEIXiao-Li; LIUYin; LIJin

    2003-01-01

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

  20. 40 CFR 721.9518 - Sinorhizobium meliloti strain RMBPC-2.

    Science.gov (United States)

    2010-07-01

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

  1. Screening of flocculant-producing strains by NTG mutagenesis

    Institute of Scientific and Technical Information of China (English)

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

    2005-01-01

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

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

    NARCIS (Netherlands)

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

    2014-01-01

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

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

    Science.gov (United States)

    Miller, Baila

    1990-01-01

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

  4. Nociception and Conditioned Fear in Rats: Strains Matter

    NARCIS (Netherlands)

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

    2013-01-01

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

  5. Bordetella pertussis Strain Lacking Pertactin and Pertussis Toxin.

    Science.gov (United States)

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

    2016-02-01

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

  6. Fabrication and mechanical characterisation of inkjet printed strain gauges

    NARCIS (Netherlands)

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

    2011-01-01

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

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

    Science.gov (United States)

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

    2016-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

    Helfer, Thomas

    2015-07-15

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

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

    Directory of Open Access Journals (Sweden)

    Cyril Hrnčár

    2013-02-01

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

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

    DEFF Research Database (Denmark)

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

    2012-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Rania Gaber

    2014-03-01

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

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

    OpenAIRE

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

    2013-01-01

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

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

    Science.gov (United States)

    Gorski, Lisa

    2012-01-01

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

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

    Science.gov (United States)

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

    2014-01-01

    A better understanding of metabolic fluxes is important for manipulating microbial metabolism toward desired end products, or away from undesirable by-products. A mutant strain, Gluconacetobacter xylinus AX2-16, was obtained by combined chemical mutation of the parent strain (G. xylinus CGMCC 2955) using DEC (diethyl sulfate) and LiCl. The highest bacterial cellulose production for this mutant was obtained at about 11.75 g/L, which was an increase of 62% compared with that by the parent strain. In contrast, gluconic acid (the main byproduct) concentration was only 5.71 g/L for mutant strain, which was 55.7% lower than that of parent strain. Metabolic flux analysis indicated that 40.1% of the carbon source was transformed to bacterial cellulose in mutant strain, compared with 24.2% for parent strain. Only 32.7% and 4.0% of the carbon source were converted into gluconic acid and acetic acid in mutant strain, compared with 58.5% and 9.5% of that in parent strain. In addition, a higher flux of tricarboxylic acid (TCA) cycle was obtained in mutant strain (57.0%) compared with parent strain (17.0%). It was also indicated from the flux analysis that more ATP was produced in mutant strain from pentose phosphate pathway (PPP) and TCA cycle. The enzymatic activity of succinate dehydrogenase (SDH), which is one of the key enzymes in TCA cycle, was 1.65-fold higher in mutant strain than that in parent strain at the end of culture. It was further validated by the measurement of ATPase that 3.53–6.41 fold higher enzymatic activity was obtained from mutant strain compared with parent strain. PMID:24901455

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

    Directory of Open Access Journals (Sweden)

    Cheng Zhong

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

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

    Science.gov (United States)

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

    2011-08-01

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

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

    Science.gov (United States)

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

    2007-03-01

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

  18. High temperature static strain gage development

    Science.gov (United States)

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

    1991-01-01

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

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

    Science.gov (United States)

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

    2014-01-01

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

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

    Science.gov (United States)

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

    2009-01-01

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

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

    NARCIS (Netherlands)

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

    2010-01-01

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

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

    Science.gov (United States)

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

    1985-01-01

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

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

    Science.gov (United States)

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

    2016-05-15

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

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

    Science.gov (United States)

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

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

    Science.gov (United States)

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

    2016-04-01

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

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

    Science.gov (United States)

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

    2014-01-01

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

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

    Directory of Open Access Journals (Sweden)

    Matheus M. Mantovani

    2012-12-01

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

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

    Science.gov (United States)

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

    2017-09-29

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

  9. Strain localization along micro-boudinage

    Science.gov (United States)

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

    2016-04-01

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

  10. Hydrogen production by recombinant Escherichia coli strains

    Science.gov (United States)

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

    2012-01-01

    Summary The production of hydrogen via microbial biotechnology is an active field of research. Given its ease of manipulation, the best‐studied bacterium Escherichia coli has become a workhorse for enhanced hydrogen production through metabolic engineering, heterologous gene expression, adaptive evolution, and protein engineering. Herein, the utility of E. coli strains to produce hydrogen, via native hydrogenases or heterologous ones, is reviewed. In addition, potential strategies for increasing hydrogen production are outlined and whole‐cell systems and cell‐free systems are compared. PMID:21895995

  11. Quantum Chemical Strain Analysis For Mechanochemical Processes.

    Science.gov (United States)

    Stauch, Tim; Dreuw, Andreas

    2017-03-24

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

  12. Isolation of a Bacterium Strain Degraded Agar

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

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

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

    Science.gov (United States)

    Parker, Allen R., Jr.

    1993-01-01

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

  14. Strain analysis of nonlocal viscoelastic Kelvin bar in tension

    Institute of Scientific and Technical Information of China (English)

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

    2008-01-01

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

  15. Occurrence and diversity of mosquitocidal strains of Bacillus thuringiensis

    Directory of Open Access Journals (Sweden)

    K. Balaraman

    2005-09-01

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

  16. Evidence for residual elastic strain in deformed natural quartz

    Energy Technology Data Exchange (ETDEWEB)

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

    2009-01-30

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

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

    Science.gov (United States)

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

    2013-03-01

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

  18. Molecular Characterization of China Human Rabies Vaccine Strains

    Institute of Scientific and Technical Information of China (English)

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

    2013-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1989-01-01

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

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

    Science.gov (United States)

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

    2014-05-01

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

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

    Science.gov (United States)

    Müller, Ina; Lurz, Rudi; Geider, Klaus

    2012-07-25

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

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

    Science.gov (United States)

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

    2012-01-01

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

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

    Science.gov (United States)

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

    2004-06-01

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

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

    Directory of Open Access Journals (Sweden)

    A. Ashok

    2010-08-01

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

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

    Science.gov (United States)

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

    2016-10-01

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

  6. Graphene spin diode: Strain-modulated spin rectification

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-08-04

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

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

    Directory of Open Access Journals (Sweden)

    Waris Obitayo

    2012-01-01

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

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

    CERN Document Server

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

    2016-01-01

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

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-08-12

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

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

    Science.gov (United States)

    Patterson, W. J.

    1979-01-01

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

  11. Mechanical control over valley magnetotransport in strained graphene

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-05-06

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

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

    Directory of Open Access Journals (Sweden)

    Sourne H.L.

    2012-08-01

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

  13. Substrate-induced strain in carbon nanodisks

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-08-28

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

  14. Aseismic strain episodes at Campi Flegrei, Italy

    Science.gov (United States)

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

    2014-05-01

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

  15. Valsalva maneuver: shortest optimal expiratory strain duration

    Directory of Open Access Journals (Sweden)

    Ramesh K. Khurana, Md

    2011-07-01

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

  16. Physics of strained quantum well lasers

    CERN Document Server

    Loehr, John P

    1998-01-01

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

  17. Major flood related strains and pregnancy outcomes.

    Science.gov (United States)

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

    2016-11-01

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

  18. Strain engineered pyrochlore at high pressure

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-05-22

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

  19. Fermentation characteristics of Dekkera bruxellensis strains.

    Science.gov (United States)

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

    2010-07-01

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

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

    Science.gov (United States)

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

    2016-09-01

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