Draft Genome Sequence of Achromobacter sp. Strain AR476-2, Isolated from a Cellulolytic Consortium.

PubMed

Kurth, Daniel; Romero, Cintia M; Fernandez, Pablo M; Ferrero, Marcela A; Martinez, M Alejandra

2016-06-23

Achromobacter sp. AR476-2 is a noncellulolytic strain previously isolated from a cellulolytic consortium selected from samples of insect gut. Its genome sequence could contribute to the unraveling of the complex interaction of microorganisms and enzymes involved in the biodegradation of lignocellulosic biomass in nature. Copyright © 2016 Kurth et al.

Bioremediation of PCB-contaminated shallow river sediments: The efficacy of biodegradation using individual bacterial strains and their consortia.

PubMed

Horváthová, Hana; Lászlová, Katarína; Dercová, Katarína

2018-02-01

Elimination of dangerous toxic and hydrophobic chlorinated aromatic compounds, mainly PCBs from the environment, is one of the most important aims of the environmental biotechnologies. In this work, biodegradation of an industrial mixture of PCBs (Delor 103, equivalent to Aroclor 1242) was performed using bacterial consortia composed of four bacterial strains isolated from the historically PCB-contaminated sediments and characterized as Achromobacter xylosoxidans, Stenotrophomonas maltophilia, Ochrobactrum anthropi and Rhodococcus ruber. The objective of this research was to determine the biodegradation ability of the individual strains and artificially prepared consortia composed of two or three bacterial strains mentioned above. Based on the growth parameters, six consortia were constructed and inoculated into the historically contaminated sediment samples collected in the efflux canal of Chemko Strážske plant - the former producer of the industrial mixtures of PCBs. The efficacy of the biotreatment, namely bioaugmentation, was evaluated by determination of ecotoxicity of treated and non-treated sediments. The most effective consortia were those containing the strain R. ruber. In the combination with A. xylosoxidans, the biodegradation of the sum of the indicator congeners was 85% and in the combination with S. maltophilia nearly 80%, with inocula applied in the ratio 1:1 in both cases. Consortium containing the strain R. ruber and S. maltophilia showed pronounced degradation of the highly chlorinated PCB congeners. Among the consortia composed of three bacterial strains, only that consisting of O. anthropi, R. ruber and A. xylosoxidans showed higher biodegradation (73%). All created consortia significally reduced the toxicity of the contaminated sediment. Copyright © 2017 Elsevier Ltd. All rights reserved.

Biodegradation of the Herbicide 2,4-Dichlorophenoxyacetic Acid by a New Isolated Strain of Achromobacter sp. LZ35.

PubMed

Xia, Zhen-Yuan; Zhang, Long; Zhao, Yan; Yan, Xin; Li, Shun-Peng; Gu, Tao; Jiang, Jian-Dong

2017-02-01

In this study, a bacterial strain of Achromobacter sp. LZ35, which was capable of utilizing 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-methyl-4-chlorophenoxy acetic acid (MCPA) as the sole sources of carbon and energy for growth, was isolated from the soil in a disused pesticide factory in Suzhou, China. The optimal 2,4-D degradation by strain LZ35 occurred at 30 °C and pH 8.0 when the initial 2,4-D concentration was 200 mg L -1 . Strain LZ35 harbored the conserved 2,4-D/alpha-ketoglutarate dioxygenase (96%) and 2,4-dichlorophenol hydroxylase (99%), and catabolized 2,4-D via the intermediate 2,4-dichlorophenol. The inoculation of 7.8 × 10 6  CFU g -1 soil of strain LZ35 cells to 2,4-D-contaminated soil could efficiently remove over 75 and 90% of 100 and 50 mg L -1 2,4-D in 12 days and significantly released the phytotoxicity of maize caused by the 2,4-D residue. This is the first report of an Achromobacter sp. strain that was capable of mineralizing both 2,4-D and MCPA. This study provides us a promising candidate for its application in the bioremediation of 2,4-D- or MCPA-contaminated sites.

First genome sequences of Achromobacter phages reveal new members of the N4 family.

PubMed

Wittmann, Johannes; Dreiseikelmann, Brigitte; Rohde, Manfred; Meier-Kolthoff, Jan P; Bunk, Boyke; Rohde, Christine

2014-01-27

Multi-resistant Achromobacter xylosoxidans has been recognized as an emerging pathogen causing nosocomially acquired infections during the last years. Phages as natural opponents could be an alternative to fight such infections. Bacteriophages against this opportunistic pathogen were isolated in a recent study. This study shows a molecular analysis of two podoviruses and reveals first insights into the genomic structure of Achromobacter phages so far. Growth curve experiments and adsorption kinetics were performed for both phages. Adsorption and propagation in cells were visualized by electron microscopy. Both phage genomes were sequenced with the PacBio RS II system based on single molecule, real-time (SMRT) technology and annotated with several bioinformatic tools. To further elucidate the evolutionary relationships between the phage genomes, a phylogenomic analysis was conducted using the genome Blast Distance Phylogeny approach (GBDP). In this study, we present the first detailed analysis of genome sequences of two Achromobacter phages so far. Phages JWAlpha and JWDelta were isolated from two different waste water treatment plants in Germany. Both phages belong to the Podoviridae and contain linear, double-stranded DNA with a length of 72329 bp and 73659 bp, respectively. 92 and 89 putative open reading frames were identified for JWAlpha and JWDelta, respectively, by bioinformatic analysis with several tools. The genomes have nearly the same organization and could be divided into different clusters for transcription, replication, host interaction, head and tail structure and lysis. Detailed annotation via protein comparisons with BLASTP revealed strong similarities to N4-like phages. Analysis of the genomes of Achromobacter phages JWAlpha and JWDelta and comparisons of different gene clusters with other phages revealed that they might be strongly related to other N4-like phages, especially of the Escherichia group. Although all these phages show a highly

Molecular and eco-physiological characterization of arsenic (As)-transforming Achromobacter sp. KAs 3-5T from As-contaminated groundwater of West Bengal, India.

PubMed

Mohapatra, Balaram; Satyanarayana, Tulasi; Sar, Pinaki

2018-05-02

Molecular and eco-physiological characterization of arsenic (As)-transforming and hydrocarbon-utilizing Achromobacter type strain KAs 3-5 T has been investigated in order to gain an insight into As-geomicrobiology in the contaminated groundwater. The bacterium is isolated from As-rich groundwater of West Bengal, India. Comparative 16S rRNA gene sequence phylogenetic analysis confirmed that the strain KAs 3-5 T is closely related to Achromobacter mucicolens LMG 26685 T (99.17%) and Achromobacter animicus LMG 26690 T (99.17%), thus affiliated to the genus Achromobacter. Strain KAs 3-5 T is nonflagellated, mesophilic, facultative anaerobe, having a broad metabolic repertoire of using various sugars, sugar-/fatty acids, hydrocarbons as principal carbon substrates, and O 2 , NO 3 - , NO 2 - , and Fe 3+ as terminal electron acceptors. Growth with hydrocarbons led to cellular aggregation and adherence of the cells to the hydrocarbon particles confirmed through electron microscopic observations. The strain KAs 3-5 T showed high As resistance (MIC of 5 mM for As 3+ , 25 mM for As 5+ ) and reductive transformation of As 5+ under aerobic conditions while utilizing both sugars and hydrocarbons. Molecular taxonomy specified a high genomic GC content (65.5 mol %), ubiquinone 8 (UQ-8) as respiratory quinone, spermidine as predominant polyamine in the bacterium. The differential presence of C 12:0 , C 14:0 2-OH, C 18:1 ω7c, and C 14:0 iso 3-OH/ C 16:1 iso fatty acids, phosphatidylglycerol (PG), phosphatidylcholine (PC), two unknown phospholipid (PL1, PL2) as polar lipids, low DNA-DNA relatedness (33.0-41.0%) with the Achromobacter members, and unique metabolic capacities clearly indicated the distinct genomic and physiological properties of strain KAs 3-5 T among known species of the genus Achromobacter. These findings lead to improve our understanding on metabolic flexibility of bacteria residing in As-contaminated groundwater and As-bacteria interactions within oligotrophic

Alcaligenes xylosoxidans endophthalmitis following phacoemulsification and intraocular lens implantation.

PubMed

Robert, Pierre-Yves; Chainier, Delphine; Garnier, Fabien; Ploy, Marie-Cécile; Parneix, Pierre; Adenis, Jean-Paul; Martin, Christian

2008-01-01

Five consecutive cases of endophthalmitis that developed after cataract extraction by a single surgeon using the same operating room during one morning session are described. Following preoperative topical administration of ciprofloxacin, surgery consisted of phacoemulsification with peristaltic pump and fluid venting, polymethylmethacrylate intraocular lens implantation, and corneal suture. No complications occurred during surgery. All five patients developed endophthalmitis caused by infection with Alcaligenes xylosoxidans in less than 24 hours. Pulsed-field gel electrophoresis was used to prove similarity between strains. Bacterial inquiry on contamination of the operating room environment revealed massive colonization of phacoemulsifier irrigation channels by Pseudomonas fluorescens bacteria from an unestablished source. Four of the five patients ultimately recovered visual acuity better than 20/60.

Impact of biogenic substrates on sulfamethoxazole biodegradation kinetics by Achromobacter denitrificans strain PR1.

PubMed

Nguyen, P Y; Carvalho, Gilda; Reis, A C; Nunes, O C; Reis, M A M; Oehmen, A

2017-06-01

Pure cultures have been found to degrade pharmaceutical compounds. However, these cultures are rarely characterized kinetically at environmentally relevant concentrations. This study investigated the kinetics of sulfamethoxazole (SMX) degradation by Achromobacter denitrificans strain PR1 at a wide range of concentrations, from ng/L to mg/L, to assess the feasibility of using it for bioaugmentation purposes. Complete removal of SMX occurred for all concentrations tested, i.e., 150 mg/L, 500 µg/L, 20 µg/L, and 600 ng/L. The reaction rate coefficients (k bio ) for the strain at the ng/L SMX range were: 63.4 ± 8.6, 570.1 ± 15.1 and 414.9 ± 124.2 L/g[Formula: see text]·day), for tests fed without a supplemental carbon source, with acetate, and with succinate, respectively. These results were significantly higher than the value reported for non-augmented activated sludge (0.41 L/(g [Formula: see text]·day) with hundreds of ng/L of SMX. The simultaneous consumption of an additional carbon source and SMX suggested that the energetic efficiency of the cells, boosted by the presence of biogenic substrates, was important in increasing the SMX degradation rate. The accumulation of 3-amino-5-methylisoxazole was observed as the only metabolite, which was found to be non-toxic. SMX inhibited the Vibrio fischeri luminescence after 5 min of contact, with EC 50 values of about 53 mg/L. However, this study suggested that the strain PR1 still can degrade SMX up to 150 mg/L. The results of this work demonstrated that SMX degradation kinetics by A. denitrificans PR1 compares favorably with activated sludge and the strain is a potentially interesting organism for bioaugmentation for SMX removal from polluted waters.

Biodegradation of 5-chloro-2-picolinic acid by novel identified co-metabolizing degrader Achromobacter sp. f1.

PubMed

Wu, Zhi-Guo; Wang, Fang; Ning, Li-Qun; Stedtfeld, Robert D; Yang, Zong-Zheng; Cao, Jing-Guo; Sheng, Hong-Jie; Jiang, Xin

2017-06-01

Several bacteria have been isolated to degrade 4-chloronitrobenzene. Degradation of 4-chloronitrobenzene by Cupriavidus sp. D4 produces 5-chloro-2-picolinic acid as a dead-end by-product, a potential pollutant. To date, no bacterium that degrades 5-chloro-2-picolinic acid has been reported. Strain f1, isolated from a soil polluted by 4-chloronitrobenzene, was able to co-metabolize 5-chloro-2-picolinic acid in the presence of ethanol or other appropriate carbon sources. The strain was identified as Achromobacter sp. based on its physiological, biochemical characteristics, and 16S rRNA gene sequence analysis. The organism completely degraded 50, 100 and 200 mg L -1 of 5-chloro-2-picolinic acid within 48, 60, and 72 h, respectively. During the degradation of 5-chloro-2-picolinic acid, Cl - was released. The initial metabolic product of 5-chloro-2-picolinic acid was identified as 6-hydroxy-5-chloro-2-picolinic acid by LC-MS and NMR. Using a mixed culture of Achromobacter sp. f1 and Cupriavidus sp. D4 for degradation of 4-chloronitrobenzen, 5-chloro-2-picolinic acid did not accumulate. Results infer that Achromobacter sp. f1 can be used for complete biodegradation of 4-chloronitrobenzene in remedial applications.

Effects of inorganic carbon on the nitrous oxide emissions and microbial diversity of an anaerobic ammonia oxidation reactor.

PubMed

Zhang, Wenjie; Wang, Dunqiu; Jin, Yue

2018-02-01

Inorganic carbon (IC) is important for anaerobic ammonium oxidation (anammox). In this study, the effects of the IC concentration on N 2 O emissions and microbial diversity in an anammox reactor were investigated. N 2 O emissions were positively correlated with IC concentrations, and IC concentrations in the range of 55-130 mg/L were optimal, considering the nitrogen removal rate and N 2 O emissions. High IC concentrations resulted in the formation of CaCO 3 on the surface of anammox granules, which impacted the diffusion conditions of the substrate. Microbial community analysis indicated that high IC concentrations decreased the populations of specific bacteria, such as Achromobacter spanius strain YJART-7, Achromobacter xylosoxidans strain IHB B 6801, and Denitratisoma oestradiolicum clone 20b_15. D. oestradiolicum clone 20b_15 appeared to be the key contributor to N 2 O emissions. High N 2 O emissions may result from changes in organic carbon sources, which lead to denitrification by D. oestradiolicum clone 20b_15. Copyright © 2017 Elsevier Ltd. All rights reserved.

Essential Oil from Origanum vulgare Completely Inhibits the Growth of Multidrug-Resistant Cystic Fibrosis Pathogens.

PubMed

Pesavento, Giovanna; Maggini, Valentina; Maida, Isabel; Lo Nostro, Antonella; Calonico, Carmela; Sassoli, Chiara; Perrin, Elena; Fondi, Marco; Mengoni, Alessio; Chiellini, Carolina; Vannacci, Alfredo; Gallo, Eugenia; Gori, Luigi; Bogani, Patrizia; Bilia, Anna Rita; Campana, Silvia; Ravenni, Novella; Dolce, Daniela; Firenzuoli, Fabio; Fani, Renato

2016-06-01

Essential oils (EOs) are known to inhibit the growth of a wide range of microorganisms. Particularly interesting is the possible use of EOs to treat multidrug-resistant cystic fibrosis (CF) pathogens. We tested the essential oil (EO) from Origanum vulgare for in vitro antimicrobial activity, against three of the major human opportunistic pathogens responsible for respiratory infections in CF patients; these are methicillin-resistant Staphylococcus aureus, Stenotrophomonas maltophilia and Achromobacter xylosoxidans. Antibiotic susceptibility of each strain was previously tested by the standard disk diffusion method. Most strains were resistant to multiple antibiotics and could be defined as multi-drug-resistant (MDR). The antibacterial activity of O. vulgare EO (OEO) against a panel of 59 bacterial strains was evaluated, with MIC and MBC determined at 24, 48 and 72 hours by a microdilution method. The OEO was effective against all tested strains, although to a different extent. The MBC and MIC of OEO for S. aureus strains were either lower or equal to 0.50%, v/v, for A. xylosoxidans strains were lower or equal to 1% and 0.50%, v/v, respectively; and for S. maltophilia strains were lower or equal to 0.25%, v/v. The results from this study suggest that OEO might exert a role as an antimicrobial in the treatment of CF infections.

Biodegradation of di-n-Butyl Phthalate by Achromobacter sp. Isolated from Rural Domestic Wastewater.

PubMed

Jin, Decai; Kong, Xiao; Li, Yujie; Bai, Zhihui; Zhuang, Guoqiang; Zhuang, Xuliang; Deng, Ye

2015-10-26

A bacterial strain W-1, isolated from rural domestic wastewater, can utilize the environmental hormone di-n-butyl phthalate (DBP) as the sole carbon and energy source. The isolated bacterium species was confirmed to belong to the genus Achromobacter based on its 16S rRNA gene sequence. The results of substrate utilization tests showed that the strain W-1 could utilize other common phthalates and phenol. High-performance liquid chromatography analysis revealed that the optimal conditions for DBP degradation were pH 7.0, 35 °C, and an agitation rate of 175 rpm. Under these conditions, 500 mg/L of DBP was completely degraded within 30 h. The effects of heavy metals (50 mg/L Cu(2+) and 500 mg/L Pb(2+)) and surfactants (100 mg/L SDS and 500 mg/L Tween 20) on DBP degradation were investigated. The results demonstrated that Cu(2+) and SDS severely inhibited DBP degradation and Pb(2+) weakly inhibited DBP degradation, while Tween 20 greatly enhanced DBP degradation. Furthermore, phthalate degradation genes were found to be located on a plasmid present in Achromobacter sp. W-1.

Isolation of a lead tolerant novel bacterial species, Achromobacter sp. TL-3: assessment of bioflocculant activity.

PubMed

Batta, Neha; Subudhi, Sanjukta; Lal, Banwari; Devi, Arundhuti

2013-11-01

Lead is one of the four heavy metals that has a profound damaging effects on human health. In the recent past there has been an increasing global concern for development of sustainable bioremediation technologies for detoxification of lead contaminant. Present investigation highlights for lead biosorption by a newly isolated novel bacterial species; Achromobacter sp. TL-3 strain, isolated from activated sludge samples contaminated with heavy metals (collected from oil refinery, Assam, North-East India). For isolation of lead tolerant bacteria, sludge samples were enriched into Luria Broth medium supplemented separately with a range of lead nitrate; 250, 500, 750, 1000, 1250 and 1500 ppm respectively. The bacterial consortium that could tolerate 1500 ppm of lead nitrate was selected further for purification of lead tolerant bacterial isolates. Purified lead tolerant bacterial isolates were then eventually inoculated into production medium supplemented with ethanol and glycerol as carbon and energy source to investigate for bioflocculant production. Bioflocculant production was estimated by monitoring the potential of lead tolerant bacterial isolate to flocculate Kaolin clay in presence of 1% CaCl2. Compared to other isolates, TL-3 isolate demonstrated for maximum bioflocculant activity of 95% and thus was identified based on 16S rRNA gene sequence analysis. TL3 isolate revealed maximum homology (98%) with Achromobacter sp. and thus designated as Achromobacter sp. TL-3. Bioflocculant activity of TL-3 isolate was correlated with the change in pH and growth. Achromobacter sp. TL-3 has significant potential for lead biosorption and can be effectively employed for detoxification of lead contaminated waste effluents/waste waters.

Degradation and mineralization of 2-chloro-, 3-chloro- and 4-chlorobiphenyl by a newly characterized natural bacterial strain isolated from an electrical transformer fluid-contaminated soil.

PubMed

Ilori, Matthew O; Robinson, Gary K; Adebusoye, Sunday A

2008-01-01

A bacterium classified as Achromobacter xylosoxidans strain IR08 by phenotypic typing coupled with 16S rRNA gene analysis was isolated from a soil contaminated with electrical transformer fluid for over sixty years using Aroclor 1221 as an enrichment substrate. The substrate utilization profiles revealed that IR08 could grow on all three monochlorobiphenyls (CBs), 2,4'- and 4,4'-dichlorobiphenyl as well as 2-chlorobenzoate (2-CBA), 3-CBA, 4-CBA, and 2,3-dichlorobenzoate. Unusually, growth was poorly sustained on biphenyl and benzoate. In growth experiments, IR08 degraded all CBs (0.27 mmol/L) in less than 96 h with concomitant stoichiometric release of inorganic chloride and growth yields were 2-3 times higher than those observed on biphenyl. In contrast to most of the chlorobiphenyl-degrading strains described in the literature, which are reported to form CBA, no metabolite was identified in the culture broth by HPLC analysis. When co-incubated with respective CBs and biphenyl, strain IR08 preferentially utilized the chlorinated analogues in less than 96 h while it took another 264 h before 90% of the initially supplied biphenyl could be degraded. The promotion of co-metabolic transformation of halogenated substrates by the inclusion of their non-halogenated derivatives may not therefore, result in universal benefits.

Bacteremia caused by Achromobacter species in an immunocompromised host.

PubMed Central

Kish, M A; Buggy, B P; Forbes, B A

1984-01-01

A case of bacteremia caused by Achromobacter species in an immunocompromised patient is described. The patient responded to antibiotic therapy. Detailed antibiotic susceptibility data are presented. PMID:6332118

Evaluation of pyrrolidonyl arylamidase for the identification of nonfermenting Gram-negative rods.

PubMed

Bombicino, Karina A; Almuzara, Marisa N; Famiglietti, Angela M R; Vay, Carlos

2007-01-01

To evaluate the activity of pyrrolidonyl arylamidase (PYR) for the differentiation and identification of nonfermenting gram negative rods (NFGNR), 293 isolates were tested. A 24 h culture of each test organism was prepared. From this a 108-109 cfu/mL suspension was added to 0.25 mL of sterile physiologic solution. A PYR disk was then added and the test was incubated for 30 minutes at 35-37 degrees C, at environmental atmosphere. Reading was done by adding 1 drop of cinnamaldehyde reagent. Strains of Acinetobacter baumannii, Acinetobacter haemolyticus, Alcaligenes faecalis, Bergeyella zoohelcum, Bordetella bronchiseptica, Bordetella hinzii, Brevundimonas diminuta, Brevundimonas vesicularis, Brucella ovis, Brucella spp., Brucella suis, Burkholderia cepacia complex, Moraxella catarrhalis, Moraxella lacunata, Moraxella nonliquefaciens, Moraxella osloensis, Oligella ureolytica, Pseudomonas alcaligenes, Pseudomonas mendocina, Pseudomonas pseudoalcaligenes, Pseudomonas putida, Pseudomonas stutzeri, Pseudomonas Vb3, Psychrobacter phenylpyruvicus, and Stenotrophomonas maltophilia were PYR negative. On the other hand Achromobacter piechaudii, Achromobacter denitrificans, Achromobacter xylosoxidans, Burkholderia gladioli, Chryseobacterium gleum-indologenes, Comamonas testosroni, Cupriavidus pauculus, Delftia acidovorans, Elizabethkingia meningoseptica, Myroides spp., Ochrobactrum anthropi, Pseudomonas oryzihabitans, Ralstonia pickettii, Rhizobium radiobacter, Shewanella spp., Sphingobacterium multivorum, Sphingobacterium spiritivorum, and Weeksella virosa were PYR positive. Finally, Acinetobacter lwoffii, Pseudomonas aeruginosa, Pseudomonas fluorescens, Roseomonas spp., and Sphingomonas paucimobilis-parapaucimobilis were PYR variable. PYR testing should be considered as a useful tool to facilitate the identification of NFGNR.

Parapusillimonas granuli gen. nov., sp. nov., isolated from granules from a wastewater-treatment bioreactor.

PubMed

Kim, Yeon-Ju; Kim, Myung Kyum; Im, Wan-Taek; Srinivasan, Sathiyaraj; Yang, Deok-Chun

2010-06-01

A novel betaproteobacterium, designated strain Ch07(T), was isolated from granules from the wastewater-treatment bioreactor of an alcohol fermentation factory in South Korea. In order to determine its taxonomic position, the novel strain was characterized using a polyphasic approach. The new strain was Gram-negative, facultatively anaerobic, non-spore-forming, motile and short rod-shaped. 16S rRNA gene sequence analysis revealed that strain Ch07(T) belonged to the class Betaproteobacteria, being related to Pusillimonas noertemannii BN9(T) (gene sequence similarity 97.30 %), Achromobacter xylosoxidans subsp. xylosoxidans DSM 10346(T) (97.09 %), Bordetella pertussis DSM 5571(T) (97.01 %), Pigmentiphaga kullae DSM 13608(T) (96.68 %) and Castellaniella defragrans DSM 1214(T) (96.47 %). The results of DNA-DNA hybridization tests showed that reassociation values were less than 62 % with respect to these closely related type strains. Chemotaxonomic data showed that strain Ch07(T) possessed ubiquinone Q-8. The G+C content of the genomic DNA was 67.9+/-0.1 mol%. The major polyamine of strain Ch07(T) was putrescine. The major polar lipids of strain Ch07(T) were phosphatidylethanolamine, followed by diphosphatidylglycerol and phosphatidylglycerol. When strain Ch07(T) was incubated on tryptic soy agar, the major cellular fatty acids were C(16 : 0), C(17 : 0) cyclo, summed feature 3 (C(16 : 1)omega7c/iso C(15 : 0) 2-OH) and summed feature 5 (C(18 : 1)omega7c/omega9t/omega12t). The results of DNA-DNA hybridizations, in combination with the chemotaxonomic and physiological data, demonstrated that strain Ch07(T) represents a novel species of a new genus, for which the name Parapusillimonas granuli gen. nov., sp. nov. is proposed. The type strain of the type species is Ch07(T) (=KCTC 12668(T)=LMG 24012(T)).

Achromobacter denitrificans Strain YD35 Pyruvate Dehydrogenase Controls NADH Production To Allow Tolerance to Extremely High Nitrite Levels

PubMed Central

Doi, Yuki; Shimizu, Motoyuki; Fujita, Tomoya; Nakamura, Akira; Takizawa, Noboru

2014-01-01

We identified the extremely nitrite-tolerant bacterium Achromobacter denitrificans YD35 that can grow in complex medium containing 100 mM nitrite (NO2−) under aerobic conditions. Nitrite induced global proteomic changes and upregulated tricarboxylate (TCA) cycle enzymes as well as antioxidant proteins in YD35. Transposon mutagenesis generated NO2−-hypersensitive mutants of YD35 that had mutations at genes for aconitate hydratase and α-ketoglutarate dehydrogenase in the TCA cycle and a pyruvate dehydrogenase (Pdh) E1 component, indicating the importance of TCA cycle metabolism to NO2− tolerance. A mutant in which the pdh gene cluster was disrupted (Δpdh mutant) could not grow in the presence of 100 mM NO2−. Nitrite decreased the cellular NADH/NAD+ ratio and the cellular ATP level. These defects were more severe in the Δpdh mutant, indicating that Pdh contributes to upregulating cellular NADH and ATP and NO2−-tolerant growth. Exogenous acetate, which generates acetyl coenzyme A and then is metabolized by the TCA cycle, compensated for these defects caused by disruption of the pdh gene cluster and those caused by NO2−. These findings demonstrate a link between NO2− tolerance and pyruvate/acetate metabolism through the TCA cycle. The TCA cycle mechanism in YD35 enhances NADH production, and we consider that this contributes to a novel NO2−-tolerating mechanism in this strain. PMID:24413603

Endosulfan induced alteration in bacterial protein profile and RNA yield of Klebsiella sp. M3, Achromobacter sp. M6, and Rhodococcus sp. M2.

PubMed

Singh, Madhu; Singh, Dileep Kumar

2014-01-30

Three bacterial strains identified as Klebsiella sp. M3, Achromobacter sp. M6 and Rhodococcus sp. M2 were isolated by soil enrichment with endosulfan followed by shake flask enrichment technique. They were efficiently degrading endosulfan in the NSM (non sulfur medium) broth. Degradation of endosulfan was faster with the cell free extract of bacterial cells grown in the sulfur deficient medium (NSM) supplemented with endosulfan than that of nutrient rich medium (Luria Bertani). In the cell free extract of NSM supplemented with endosulfan as sole sulfur source, a unique band was visualized on SDS-PAGE but not with magnesium sulfate as the sole sulfur source in NSM and LB with endosulfan. Expression of a unique polypeptide band was speculated to be induced by endosulfan under sulfur starved condition. These unique polypeptide bands were identified as OmpK35 protein, sulfate binding protein and outer membrane porin protein, respectively, in Klebsiella sp. M3, Achromobacter sp. M6 and Rhodococcus sp. M2. Endosulfan showed dose dependent negative effect on total RNA yield of bacterial strains in nutrient rich medium. Absence of plasmid DNA indicated the presence of endosulfan metabolizing gene on genomic DNA. Copyright © 2013 Elsevier B.V. All rights reserved.

Intracardiac abscess with cutaneous fistula secondary to ventricular septal defect repair simulating sternal wound infection.

PubMed

Rafael, Aldo Elmer; Keshavamurthy, Suresh; Sepulveda, Edgardo; Miranda, Cyndee Cruz; Okamoto, Toshihiro; Pettersson, Gosta Bengt

2014-06-01

Cutaneous fistula as a clinical presentation of intracardiac abscess of the right side is such an unusual occurrence that it has not until now been reported in the English-language medical literature. We present a rare case of right-sided infective endocarditis caused by Achromobacter xylosoxidans in which recurrent infection presented as sternal wound discharge. The infection was found to have an intracardiac origin and was successfully managed by radical débridement on cardiopulmonary bypass.

Intracardiac Abscess with Cutaneous Fistula Secondary to Ventricular Septal Defect Repair Simulating Sternal Wound Infection

PubMed Central

Keshavamurthy, Suresh; Sepulveda, Edgardo; Miranda, Cyndee Cruz; Okamoto, Toshihiro; Pettersson, Gosta Bengt

2014-01-01

Cutaneous fistula as a clinical presentation of intracardiac abscess of the right side is such an unusual occurrence that it has not until now been reported in the English-language medical literature. We present a rare case of right-sided infective endocarditis caused by Achromobacter xylosoxidans in which recurrent infection presented as sternal wound discharge. The infection was found to have an intracardiac origin and was successfully managed by radical débridement on cardiopulmonary bypass. PMID:24955054

Got black swimming dots in your cell culture? Identification of Achromobacter as a novel cell culture contaminant

PubMed Central

Gray, Jennifer Sue; Birmingham, Janette Marie; Fenton, Jenifer Imig

2009-01-01

ARTICLE SUMMARY Cell culture model systems are utilized for their ease of use, relative inexpensiveness, and potentially limitless sample size. Reliable results cannot be obtained, however, when cultures contain contamination. This report discusses the observation and identification of mobile black specks observed in multiple cell lines. Cultures of the contamination were grown, and DNA was purified from isolated colonies. The 16S rDNA gene was PCR amplified using primers that will amplify the gene from many genera, and then sequenced. Sequencing results matched the members of the genus Achromobacter, bacteria common in the environment. Achromobacter species have been shown to be resistant to multiple antibiotics. Attempts to decontaminate the eukaryotic cell culture used multiple antibiotics at different concentrations. The contaminating Achromobacter was eventually eliminated, without permanently harming the eukaryotic cells, using a combination of the antibiotics ciprofloxacin and piperacillin. PMID:19926304

Whole genome analysis of six organophosphate-degrading rhizobacteria reveals putative agrochemical degradation enzymes with broad substrate specificity.

PubMed

Iyer, Rupa; Iken, Brian; Damania, Ashish; Krieger, Jerry

2018-05-01

Six organophosphate-degrading bacterial strains collected from farm and ranch soil rhizospheres across the Houston-metropolitan area were identified as strains of Pseudomonas putida (CBF10-2), Pseudomonas stutzeri (ODKF13), Ochrobactrum anthropi (FRAF13), Stenotrophomonas maltophilia (CBF10-1), Achromobacter xylosoxidans (ADAF13), and Rhizobium radiobacter (GHKF11). Whole genome sequencing data was assessed for relevant genes, proteins, and pathways involved in the breakdown of agrochemicals. For comparative purposes, this analysis was expanded to also include data from deposited strains in the National Center for Biotechnology Information's (NCBI) database. This study revealed Zn-dependent metallo-β-lactamase (MBL)-fold proteins similar to OPHC2 first identified in P. pseudoalcaligenes as the likely agents of organophosphate (OP) hydrolysis in A. xylosoxidans ADAF13, S. maltophilia CBF10-1, O. anthropi FRAF13, and R. radiobacter GHKF11. A search of similar proteins within NCBI identified over 200 hits for bacterial genera and species with a similar OPHC2 domain. Taken together, we conclude from this data that intrinsic low-level OP hydrolytic activity is likely prevalent across the rhizosphere stemming from widespread OPHC2-like metalloenzymes. In addition, P. stutzeri ODKF13, P. putida CBF10-2, O. anthropi FRAF13, and R. radiobacter GHKF11 were found to harbor glycine oxidase (GO) enzymes that putatively possess low-level activity against the herbicide glyphosate. These bacterial GOs are reported to catalyze the degradation of glyphosate to α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and suggest a possible link to AMPA that can be found in glyphosate-contaminated agricultural soil. The presence of aromatic degradation proteins were also detected in five of six study strains, but are attributed primarily to components of the widely distributed β-ketoadipate pathway found in many soil bacteria.

1-Aminocyclopropane-1-carboxylic acid (ACC) deaminase-containing rhizobacteria protect Ocimum sanctum plants during waterlogging stress via reduced ethylene generation.

PubMed

Barnawal, Deepti; Bharti, Nidhi; Maji, Deepamala; Chanotiya, Chandan Singh; Kalra, Alok

2012-09-01

Ocimum sanctum grown as rain-fed crop, is known to be poorly adapted to waterlogged conditions. Many a times the crop suffers extreme damages because of anoxia and excessive ethylene generation due to waterlogging conditions present under heavy rain. The usefulness of 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase-containing plant growth promoting rhizobacteria was investigated under waterlogging stress. The comparison of herb yield and stress induced biochemical changes of waterlogged and non-waterlogged plants with and without ACC deaminase-containing microbiological treatments were monitored in this study. Ten plant growth promoting rhizobacteria strains containing ACC-deaminase were isolated and characterized. Four selected isolates Fd2 (Achromobacter xylosoxidans), Bac5 (Serratia ureilytica), Oci9 (Herbaspirillum seropedicae) and Oci13 (Ochrobactrum rhizosphaerae) had the potential to protect Ocimum plants from flood induced damage under waterlogged glass house conditions. Pot experiments were conducted to evaluate the potential of these ACC deaminase-containing selected strains for reducing the yield losses caused by waterlogging conditions. Bacterial treatments protected plants from waterlogging induced detrimental changes like stress ethylene production, reduced chlorophyll concentration, higher lipid peroxidation, proline concentration and reduced foliar nutrient uptake. Fd2 (A. xylosoxidans) induced maximum waterlogging tolerance as treated waterlogged plants recorded maximum growth and herb yield (46.5% higher than uninoculated waterlogged plants) with minimum stress ethylene levels (53% lower ACC concentration as compared to waterlogged plants without bacterial inoculation) whereas under normal non-waterlogged conditions O. rhizosphaerae was most effective in plant growth promotion. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Modification of surface and enzymatic properties of Achromobacter denitrificans and Stenotrophomonas maltophilia in association with diesel oil biodegradation enhanced with alkyl polyglucosides.

PubMed

Sałek, Karina; Zgoła-Grześkowiak, Agnieszka; Kaczorek, Ewa

2013-11-01

The article concerns the influence of selected alkyl polyglucosides on biodegradation, cell surface and enzymatic properties of Stenotrophomonas maltophilia and Achromobacter denitrificans. The biodegradation of diesel oil depends on several factors including type and the amount of surfactant as well as bacterial genera used in the process. Nevertheless, a careful selection of these variables must be made as some bacterial strains prefer to use surfactants as their carbon source. This leads to the lowered biodegradation of diesel oil as can be observed for the tested S. maltophilia strain. Alkyl polyglucosides influenced the cell surface properties of both of the tested strains in slightly different ways. Especially for A. denitrificans, for which the hydrophobicity increased with concentration of both--Lutensol GD 70 and Glucopon 215 in diesel oil-surfactant systems. Moreover, judging by the efficiency of biodegradation, the most effective process was observed in the presence of Lutensol GD 70 (240 and 360 mg L(-1)) with biodegradation rising from 32% (without surfactant) to 68%. No such relation was observed for S. maltophilia. Copyright © 2013 Elsevier B.V. All rights reserved.

Genome Sequencing Reveals the Potential of Achromobacter sp. HZ01 for Bioremediation

PubMed Central

Hong, Yue-Hui; Ye, Cong-Cong; Zhou, Qian-Zhi; Wu, Xiao-Ying; Yuan, Jian-Ping; Peng, Juan; Deng, Hailin; Wang, Jiang-Hai

2017-01-01

Petroleum pollution is a severe environmental issue. Comprehensively revealing the genetic backgrounds of hydrocarbon-degrading microorganisms contributes to developing effective methods for bioremediation of crude oil-polluted environments. Marine bacterium Achromobacter sp. HZ01 is capable of degrading hydrocarbons and producing biosurfactants. In this study, the draft genome (5.5 Mbp) of strain HZ01 has been obtained by Illumina sequencing, containing 5,162 predicted genes. Genome annotation shows that “amino acid metabolism” is the most abundant metabolic pathway. Strain HZ01 is not capable of using some common carbohydrates as the sole carbon sources, which is due to that it contains few genes associated with carbohydrate transport and lacks some important enzymes related to glycometabolism. It contains abundant proteins directly related to petroleum hydrocarbon degradation. AlkB hydroxylase and its homologs were not identified. It harbors a complete enzyme system of terminal oxidation pathway for n-alkane degradation, which may be initiated by cytochrome P450. The enzymes involved in the catechol pathway are relatively complete for the degradation of aromatic compounds. This bacterium lacks several essential enzymes for methane oxidation, and Baeyer-Villiger monooxygenase involved in the subterminal oxidation pathway and cycloalkane degradation was not identified. These results suggest that strain HZ01 degrades n-alkanes via the terminal oxidation pathway, degrades aromatic compounds primarily via the catechol pathway and cannot perform methane oxidation or cycloalkane degradation. Additionally, strain HZ01 possesses abundant genes related to the metabolism of secondary metabolites, including some genes involved in biosurfactant (such as glycolipids and lipopeptides) synthesis. The genome analysis also reveals its genetic basis for nitrogen metabolism, antibiotic resistance, regulatory responses to environmental changes, cell motility, and material

Culturable bacteria present in the fluid of the hooded-pitcher plant Sarracenia minor based on 16S rDNA gene sequence data.

PubMed

Siragusa, Alex J; Swenson, Janice E; Casamatta, Dale A

2007-08-01

The culturable microbial community within the pitcher fluid of 93 Sarracenia minor carnivorous plants was examined over a 2-year study. Many aspects of the plant/bacterial/insect interaction within the pitcher fluid are minimally understood because the bacterial taxa present in these pitchers have not been identified. Thirteen isolates were characterized by 16S rDNA sequencing and subsequent phylogenetic analysis. The Proteobacteria were the most abundant taxa and included representatives from Serratia, Achromobacter, and Pantoea. The Actinobacteria Micrococcus was also abundant while Bacillus, Lactococcus, Chryseobacterium, and Rhodococcus were infrequently encountered. Several isolates conformed to species identifiers (>98% rDNA gene sequence similarity) including Serratia marcescens (isolates found in 27.5% of pitchers), Achromobacter xylosoxidans (37.6%), Micrococcus luteus (40.9%), Bacillus cereus (isolates found in 10.2%), Bacillus thuringiensis (5.4%), Lactococcus lactis (17.2%), and Rhodococcus equi (2.2%). Species-area curves suggest that sampling efforts were sufficient to recover a representative culturable bacterial community. The bacteria present represent a diverse community probably as a result of introduction by insect vectors, but the ecological significance remains under explored.

Degradation of petroleum hydrocarbons and treatment of refinery wastewater under saline condition by a halophilic bacterial consortium enriched from marine environment (Red Sea), Jeddah, Saudi Arabia.

PubMed

Jamal, Mamdoh T; Pugazhendi, Arulazhagan

2018-06-01

A halophilic bacterial consortium was enriched from Red Sea saline water and sediment samples collected from Abhor, Jeddah, Saudi Arabia. The consortium potentially degraded different low (above 90% for phenanthrene and fluorene) and high (69 ± 1.4 and 56 ± 1.8% at 50 and 100 mg/L of pyrene) molecular weight polycyclic aromatic hydrocarbons (PAHs) at different concentrations under saline condition (40 g/L NaCl concentration). The cell hydrophobicity (91° ± 1°) and biosurfactant production (30 mN/m) confirmed potential bacterial cell interaction with PAHs to facilitate biodegradation process. Co-metabolic study with phenanthrene as co-substrate during pyrene degradation recorded 90% degradation in 12 days. The consortium in continuous stirred tank reactor with petroleum refinery wastewater showed complete and 90% degradation of low and high molecular weight PAHs, respectively. The reactor study also revealed 94 ± 1.8% chemical oxygen demand removal by the halophilic consortium under saline condition (40 g/L NaCl concentration). The halophilic bacterial strains present in the consortium were identified as Ochrobactrum halosaudis strain CEES1 (KX377976), Stenotrophomonas maltophilia strain CEES2 (KX377977), Achromobacter xylosoxidans strain CEES3 (KX377978) and Mesorhizobium halosaudis strain CEES4 (KX377979). Thus, the promising halophilic consortium was highly recommended to be employed in petroleum saline wastewater treatment process.

Bioflocculant production and biosorption of zinc and lead by a novel bacterial species, Achromobacter sp. TERI-IASST N, isolated from oil refinery waste.

PubMed

Subudhi, Sanjukta; Batta, Neha; Pathak, Mihirjyoti; Bisht, Varsha; Devi, Arundhuti; Lal, Banwari; Al khulifah, Bader

2014-10-01

A bioflocculant-producing bacterial isolate designated as 'TERI-IASST N' was isolated from activated sludge samples collected from an oil refinery. This isolate demonstrated maximum bioflocculation activity (74%) from glucose among 15 different bioflocculant-producing bacterial strains isolated from the sludge samples and identified as Achromobacter sp. based on 16S rRNA gene sequence. Optimization of pH and supplementation of urea as nitrogen source in the production medium enhanced the flocculation activity of strain TERI-IASST N to 84% (at pH 6). This strain revealed maximum flocculation activity (90%) from sucrose compared to the flocculation activity observed from other carbon sources as investigated (glucose, lactose, fructose, maltose and starch). Ca(2+) served as the suitable divalent cation for maximum bioflocculation activity of TERI-IASST strain N. Maximum flocculation activity was observed at optimum C/N ratio of 1. Flocculation activity of this strain decreased to 75% in the presence of heavy metals; Zn, Pb, Ni, Cu and Cd. In addition strain N revealed considerable biosorption of Zn (430mgL(-1)) and Pb (30mgL(-1)). Bioflocculant yield of strain N was 10.5gL(-1). Fourier transform infrared spectrum indicated the presence of carboxyl, hydroxyl, and amino groups, typical of glycoprotein. Spectroscopic analysis of bioflocculant by nuclear magnetic resonance revealed that it is a glycoprotein, consisting of 57% total sugar and 13% protein. Copyright © 2014 Elsevier Ltd. All rights reserved.

Achromobacter denitrificans SP1 produces pharmaceutically active 25C prodigiosin upon utilizing hazardous di(2-ethylhexyl)phthalate.

PubMed

Pradeep, S; Sarath Josh, M K; Balachandran, S; Sudha Devi, R; Sadasivam, R; Thirugnanam, P E; Doble, Mukesh; Anderson, Robin C; Benjamin, Sailas

2014-11-01

This first report describes the purification and identification of an orange-red pigment produced by Achromobacter denitrificans strain SP1 (isolated from sewage sludge heavily contaminated with plastics) during its growth in a simple basal salt medium supplemented with the hazardous di(2-ethylhexyl)phthalate (DEHP) blended in PVC blood bag (in situ) or free DEHP (ex situ) as carbon source. The cell-bound pigment was elucidated, characterized at molecular level, and described as an unusual 25C prodigiosin analog for the first time. At laboratory conditions (in flasks), the dry cell mass was 75.2mg/g blood bag, which upon extraction yielded 7.1mg prodigiosin; at this stage the pH of the medium was dropped from 7.2 to 3.5. Considering its pharmaceutical importance, taking 10 known prodigiosins as controls, this 25C prodigiosin was subjected to molecular docking studies, showed comparable and promising binding efficiencies with the crucial molecular human targets like cycloxygenase-2, ZAP-70 kinase and Jak-3 kinase. Copyright © 2014 Elsevier Ltd. All rights reserved.

Nucleic Acid Homologies Among Oxidase-Negative Moraxella Species

PubMed Central

Johnson, John L.; Anderson, Robert S.; Ordal, Erling J.

1970-01-01

The deoxyribonucleic acid (DNA) base composition and DNA homologies of more than 40 strains of oxidase-negative Moraxella species were determined. These bacteria have also been identified as belonging to the Mima-Herellea-Acinetobacter group and the Bacterium anitratum group, as well as to several other genera including Achromobacter and Alcaligenes. The DNA base content of these strains ranged from 40 to 46% guanine plus cytosine. DNA–DNA competition experiments distinguished five groups whose members were determined by showing 50% or more homology to one of the reference strains: B. anitratum type B5W, Achromobacter haemolyticus var. haemolyticus, Alcaligenes haemolysans, Achromobacter metalcaligenes, and Moraxella lwoffi. A sixth group comprised those strains showing less than 50% homology to any of the reference strains. Negligible homology was found between strains of oxidase-negative and oxidase-positive Moraxella species in DNA–DNA competition experiments. However, evidence of a distant relationship between the two groups was obtained in competition experiments by using ribosomal ribonucleic acid. PMID:5413826

Biodegradation of bispyribac sodium by a novel bacterial consortium BDAM: Optimization of degradation conditions using response surface methodology.

PubMed

Ahmad, Fiaz; Anwar, Samina; Firdous, Sadiqa; Da-Chuan, Yin; Iqbal, Samina

2018-05-05

Bispyribac sodium (BS), is a selective, systemic and post emergent herbicide used to eradicate grasses and broad leaf weeds. Extensive use of this herbicide has engendered serious environmental concerns. Hence it is important to develop strategies for bioremediation of BS in a cost effective and environment friendly way. In this study a bacterial consortium named BDAM, comprising three novel isolates Achromobacter xylosoxidans (BD1), Achromobacter pulmonis (BA2), and Ochrobactrum intermedium (BM2), was developed by virtue of its potential for degradation of BS. Different culture conditions (temperature, pH and inoculum size) were optimized for degradation of BS by the consortium BDAM and the mutual interactions of these parameters were analysed using a 2 3 full factorial central composite design (CCD) based on Response Surface Methodology (RSM). The optimal values for temperature, pH and inoculum size were found to be 40 °C, 8 and 0.4 g/L respectively to achieve maximum degradation of BS (85.6%). Moreover, the interactive effects of these parameters were investigated using three dimensional surface plots in terms of maximum fitness function. Importantly, it was concluded that the newly developed consortium is a potential candidate for biodegradation of BS in a safe, cost-effective and environmentally friendly manner. Copyright © 2017. Published by Elsevier B.V.

Effect of metal ions and petrochemicals on bioremediation of chlorpyrifos in aerobic sequencing batch bioreactor (ASBR).

PubMed

Khalid, Saira; Hashmi, Imran; Jamal Khan, Sher; Qazi, Ishtiaq A; Nasir, Habib

2016-10-01

Application of chlorpyrifos (CP) has increased its environmental concentration. Increasing CP concentration has increased chances of adverse health effects. Its removal from environment has attained researcher's attention. CP degrading bacterial strains were isolated from wastewater and agricultural soil. Finally, selected five bacterial strains were identified using 16S rRNA nucleotide sequence analysis as Pseudomonas kilonensis SRK1, Serratia marcescens SRK2, Bacillus pumilus SRK4, Achromobacter xylosoxidans SRK5, and Klebsiella sp. T13. Interaction studies among bacterial strains demonstrated possibility for development of five membered bacterial consortium. Biodegradation potential of bacterial consortium was investigated in the presence of petrochemicals and trace metals. About 98 % CP removal was observed in sequencing batch reactors at inoculum level, 10 %; pH, 7; CP concentration, 400 mgL -1 , and HRT, 48 h. Experimental data has shown an excellent fit to first order growth model. Among all petrochemicals only toluene (in low concentration) has stimulatory effect on biodegradation of CP. Addition of petrochemicals (benzene, toluene, and xylene) in high concentration (100 mg L -1 ) inhibited bacterial activity and decreased CP removal. At low concentration i.e., 1 mg L -1 of inorganic contaminants (Cu, Hg, and Zn) >96 % degradation was observed. Addition of Cu(II) in low concentration has stimulated CP removal efficiency. Hg(II) in all concentrations has strongly inhibited biodegradation rate except at 1 mgL -1 . In simulated pesticide, wastewater CP removal efficiency decreased to 77.5 %. Outcomes of study showed that both type and concentration of petrochemicals and trace metals influenced biodegradation of CP.

Changing Epidemiology of the Respiratory Bacteriology of Patients With Cystic Fibrosis.

PubMed

Salsgiver, Elizabeth L; Fink, Aliza K; Knapp, Emily A; LiPuma, John J; Olivier, Kenneth N; Marshall, Bruce C; Saiman, Lisa

2016-02-01

Monitoring potential changes in the epidemiology of cystic fibrosis (CF) pathogens furthers our understanding of the potential impact of interventions. We performed a retrospective analysis using data reported to the Cystic Fibrosis Foundation Patient Registry (CFFPR) from 2006 to 2012 to determine the annual percent changes in the prevalence and incidence of selected CF pathogens. Pathogens included Pseudomonas aeruginosa, methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant S aureus (MRSA), Haemophilus influenzae, Burkholderia cepacia complex, Stenotrophomonas maltophilia, and Achromobacter xylosoxidans. Changes in nontuberculous mycobacteria (NTM) prevalence were assessed from 2010 to 2012, when the CFFPR collected NTM species. In 2012, the pathogens of highest prevalence and incidence were MSSA and P aeruginosa, followed by MRSA. The prevalence of A xylosoxidans and B cepacia complex were relatively low. From 2006 to 2012, the annual percent change in overall (as well as in most age strata) prevalence and incidence significantly decreased for P aeruginosa and B cepacia complex, but significantly increased for MRSA. From 2010 to 2012, the annual percent change in overall prevalence of NTM and Mycobaterium avium complex increased. The epidemiology of CF pathogens continues to change. The causes of these observations are most likely multifactorial and include improvements in clinical care and infection prevention and control. Data from this study will be useful to evaluate the impact of new therapies on CF microbiology. Copyright © 2016 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.

Resonance Raman spectra of the copper-sulfur chromophores in Achromobacter cycloclastes nitrite reductase.

PubMed

Dooley, D M; Moog, R S; Liu, M Y; Payne, W J; LeGall, J

1988-10-15

Resonance Raman spectroscopy at ambient temperature and 77 K has been used to probe the structures of the copper sites in Achromobacter cycloclastes nitrite reductase. This enzyme contains three copper ions per protein molecule and has two principal electronic absorption bands with lambda max values of 458 and 585 nm. Comparisons between the resonance Raman spectra of nitrite reductase and blue copper proteins establish that both the 458 and 585 nm bands are associated with Cu(II)-S(Cys) chromophores. A histidine ligand probably is also present. Different sets of vibrational frequencies are observed with 457.9 nm (ambient) or 476.1 nm (77 K) excitation as compared with 590 nm (ambient) or 593 nm (77 K) excitation. Excitation profiles indicate that the 458 and 585 nm absorption bands are associated with separate [Cu(II)-S(Cys)N(His)] sites or with inequivalent and uncoupled cysteine ligands in the same site. The former possibility is considered to be more likely.

Effect of flagella expression on adhesion of Achromobacter piechaudii to chalk surfaces.

PubMed

Nejidat, A; Saadi, I; Ronen, Z

2008-12-01

To examine flagella role and cell motility in adhesion of Achromobacter piechaudii to chalk. Transmission electron microscopy revealed that stationary cells have thicker and longer flagella than logarithmic cells. SDS-PAGE analysis showed that flagellin was more abundant in stationary cells than logarithmic ones. Sonication or inhibition of flagellin synthesis caused a 30% reduction in adhesion to chalk. Preincubation of chalk with flagella extracts reduced adhesion, by 50%. Three motility mutants were isolated. Mutants 94 and 153 were nonmotile, expressed normal levels of flagellin, have regular flagella and exhibited reduced adhesion. Mutant 208 expressed low levels of flagellin, no flagella and a spherical cell shape but with normal adhesion capacity. Multiple cell surface factors affect the adhesion efficiency to chalk. Flagella per se through physical interaction and through cell motility contribute to the adhesion process. The adhesion behaviour of mutant 208 suggests that cell shape can compensate for flagellar removal and motility. Physiological status affects bacterial cell surface properties and hence adhesion efficiency to chalk. This interaction is essential to sustain biodegradation activities and thus, remediation of contaminated chalk aquifers.

Efficacy of polysaccharide from Alcaligenes xylosoxidans MSA3 administration as protection against γ-radiation in female rats

PubMed Central

Hassan, Amal I.; Ghoneim, Mona A. M.; Mahmoud, Manal G.; Asker, Mohsen M. S.; Mohamed, Saher S.

2016-01-01

Damage to normal tissues is a consequence of both therapeutic and accidental exposures to ionizing radiation. A water-soluble heteropolysaccharide called AXEPS, composed of glucose, galactose, rhamnose and glucouronic acid in a molar ratio of nearly 1.0:1.6:0.4:2.3, respectively, was isolated from culture medium of strain Alcaligenes xylosoxidans MSA3 by ethanol precipitation followed by freeze-drying. Chemical analysis, Fourier-transform infrared (FTIR) and chromatographic studies revealed that the molecular weight was 1.6 × 104 g mol−1. This study was designed to investigate the radioprotective and biological effects of AXEPS in alleviating the toxicity of ionizing radiation in female albino rats. A total of 32 female albino rats were divided into four groups. In the control group, rats were administered vehicle by tube for four weeks. The second group was administered AXEPS (100 mg/kg) orally by gavage for four weeks. Animals in the third group were exposed to whole-body γ-rays (5 Gy) and remained for 2 weeks without treatment. The fourth group received AXEPS (100 mg/kg) orally by gavage for two weeks before being exposed to whole-body γ-rays (5 Gy), then 24 h post γ-rays, they received AXEPS (100 mg/kg) in a treatment continuing till the end of the experiment (15 days after the whole–body γ-irradiation). Oral administration of AXEPS (100 mg/kg) significantly reversed the oxidative stress effects of radiation, as evidenced by the decrease in DNA damage in the bone marrow. Assessment of apoptosis and cell proliferation markers revealed that caspase-3 significantly increased in the irradiated group. Moreover, a significant decrease in the hematological constituents of peripheral blood, the chemotactic index and CD8+ T cells were observed in animals in the irradiation-only group, whereas an increase in the lymphocyte index was observed in animals in that group. In contrast, AXEPS treatment prevented these alterations. From our results, we conclude that

Seasonality of acquisition of respiratory bacterial pathogens in young children with cystic fibrosis.

PubMed

Psoter, Kevin J; De Roos, Anneclaire J; Wakefield, Jon; Mayer, Jonathan D; Rosenfeld, Margaret

2017-06-09

Seasonal variations are often observed for respiratory tract infections; however, limited information is available regarding seasonal patterns of acquisition of common cystic fibrosis (CF)-related respiratory pathogens. We previously reported differential seasonal acquisition of Pseudomonas aeruginosa in young children with CF and no such variation for methicillin-susceptible Staphylococcus aureus acquisition. The purpose of this study was to describe and compare the seasonal incidence of acquisition of other respiratory bacterial pathogens in young children with CF. We conducted a retrospective study to describe and compare the seasonal incidence of methicillin-resistant Staphylococcus aureus (MRSA), Stenotrophomonas maltophilia, Achromobacter xylosoxidans, and Haemophilus influenzae acquisition in young CF patients residing in the U.S. using the Cystic Fibrosis Foundation National Patient Registry, 2003-2009. Log-linear overdispersed Poisson regression was used to evaluate seasonal acquisition of each of these pathogens. A total of 4552 children met inclusion criteria. During follow-up 910 (20%), 1161 (26%), 228 (5%), and 2148 (47%) children acquired MRSA, S. maltophilia, A. xylosoxidans and H. influenzae, respectively. Compared to winter season, MRSA was less frequently acquired in spring (Incidence Rate Ratio [IRR]: 0.79; 95% Confidence Interval [CI]: 0.65, 0.96) and summer (IRR: 0.69; 95% CI: 0.57, 0.84) seasons. Similarly, a lower rate of A. xylosoxidans acquisition was observed in spring (IRR: 0.59; 95% CI: 0.39, 0.89). For H. influenzae, summer (IRR: 0.88; 95% CI: 0.78, 0.99) and autumn (IRR: 0.78; 95% CI: 0.69, 0.88) seasons were associated with lower acquisition rates compared to winter. No seasonal variation was observed for S. maltophilia acquisition. Acquisition of CF-related respiratory pathogens displays seasonal variation in young children with CF, with the highest rate of acquisition for most pathogens occurring in the winter. Investigation of

Poorly processed reusable surface disinfection tissue dispensers may be a source of infection.

PubMed

Kampf, Günter; Degenhardt, Stina; Lackner, Sibylle; Jesse, Katrin; von Baum, Heike; Ostermeyer, Christiane

2014-01-21

Reusable surface disinfectant tissue dispensers are used in hospitals in many countries because they allow immediate access to pre-soaked tissues for targeted surface decontamination. On the other hand disinfectant solutions with some active ingredients may get contaminated and cause outbreaks. We determined the frequency of contaminated surface disinfectant solutions in reusable dispensers and the ability of isolates to multiply in different formulations. Reusable tissue dispensers with different surface disinfectants were randomly collected from healthcare facilities. Solutions were investigated for bacterial contamination. The efficacy of two surface disinfectants was determined in suspension tests against two isolated species directly from a contaminated solution or after 5 passages without selection pressure in triplicate. Freshly prepared use solutions were contaminated to determine survival of isolates. 66 dispensers containing disinfectant solutions with surface-active ingredients were collected in 15 healthcare facilities. 28 dispensers from nine healthcare facilities were contaminated with approximately 107 cells per mL of Achromobacter species 3 (9 hospitals), Achromobacter xylosoxidans or Serratia marcescens (1 hospital each). In none of the hospitals dispenser processing had been adequately performed. Isolates regained susceptibility to the disinfectants after five passages without selection pressure but were still able to multiply in different formulations from different manufacturers at room temperature within 7 days. Neglecting adequate processing of surface disinfectant dispensers has contributed to frequent and heavy contamination of use-solutions based on surface active ingredients. Tissue dispenser processing should be taken seriously in clinical practice.

Poorly processed reusable surface disinfection tissue dispensers may be a source of infection

PubMed Central

2014-01-01

Background Reusable surface disinfectant tissue dispensers are used in hospitals in many countries because they allow immediate access to pre-soaked tissues for targeted surface decontamination. On the other hand disinfectant solutions with some active ingredients may get contaminated and cause outbreaks. We determined the frequency of contaminated surface disinfectant solutions in reusable dispensers and the ability of isolates to multiply in different formulations. Methods Reusable tissue dispensers with different surface disinfectants were randomly collected from healthcare facilities. Solutions were investigated for bacterial contamination. The efficacy of two surface disinfectants was determined in suspension tests against two isolated species directly from a contaminated solution or after 5 passages without selection pressure in triplicate. Freshly prepared use solutions were contaminated to determine survival of isolates. Results 66 dispensers containing disinfectant solutions with surface-active ingredients were collected in 15 healthcare facilities. 28 dispensers from nine healthcare facilities were contaminated with approximately 107 cells per mL of Achromobacter species 3 (9 hospitals), Achromobacter xylosoxidans or Serratia marcescens (1 hospital each). In none of the hospitals dispenser processing had been adequately performed. Isolates regained susceptibility to the disinfectants after five passages without selection pressure but were still able to multiply in different formulations from different manufacturers at room temperature within 7 days. Conclusions Neglecting adequate processing of surface disinfectant dispensers has contributed to frequent and heavy contamination of use-solutions based on surface active ingredients. Tissue dispenser processing should be taken seriously in clinical practice. PMID:24447780

Exposure of Sink Drain Microcosms to Triclosan: Population Dynamics and Antimicrobial Susceptibility

PubMed Central

McBain, Andrew J.; Bartolo, Robert G.; Catrenich, Carl E.; Charbonneau, Duane; Ledder, Ruth G.; Price, Bradford B.; Gilbert, Peter

2003-01-01

Recent concern that the increased use of triclosan (TCS) in consumer products may contribute to the emergence of antibiotic resistance has led us to examine the effects of TCS dosing on domestic-drain biofilm microcosms. TCS-containing domestic detergent (TCSD) markedly lowered biofouling at 50% (wt/vol) but was poorly effective at use levels. Long-term microcosms were established and stabilized for 6 months before one was subjected to successive 3-month exposures to TCSD at sublethal concentrations (0.2 and 0.4% [wt/vol]). Culturable bacteria were identified by 16S rDNA sequence analysis, and their susceptibilities to four biocides and six antibiotics were determined. Microcosms harbored ca. 10 log10 CFU/g of biofilm, representing at least 27 species, mainly gamma proteobacteria, and maintained dynamic stability. Viable cell counts were largely unaffected by TCSD exposure, but species diversity was decreased, as corroborated by denaturing gradient gel electrophoresis analysis. TCS susceptibilities ranged widely within bacterial groups, and TCS-tolerant strains (including aeromonads, pseudomonads, stenotrophomonads, and Alcaligenes spp.) were isolated before and after TCSD exposure. Several TCS-tolerant bacteria related to Achromobacter xylosoxidans became clonally expanded during dosing. TCSD addition did not significantly affect the community profiles of susceptibility to the test biocides or antibiotics. Several microcosm isolates, as well as reference bacteria, caused clearing of particulate TCS in solid media. Incubations of consortia and isolates with particulate TCS in liquid led to putative TCS degradation by the consortia and TCS solubilization by the reference strains. Our results support the view that low-level exposure of environmental microcosms to TCS does not affect antimicrobial susceptibility and that TCS is degradable by common domestic biofilms. PMID:12957932

Efficacy of surface disinfectant cleaners against emerging highly resistant gram-negative bacteria

PubMed Central

2014-01-01

Background Worldwide, the emergence of multidrug-resistant gram-negative bacteria is a clinical problem. Surface disinfectant cleaners (SDCs) that are effective against these bacteria are needed for use in high risk areas around patients and on multi-touch surfaces. We determined the efficacy of several SDCs against clinically relevant bacterial species with and without common types of multidrug resistance. Methods Bacteria species used were ATCC strains; clinical isolates classified as antibiotic-susceptible; and multi-resistant clinical isolates from Klebsiella oxytoca, Klebsiella pneumoniae, and Serratia marcescens (all OXA-48 and KPC-2); Acinetobacter baumannii (OXA-23); Pseudomonas aeruginosa (VIM-1); and Achromobacter xylosoxidans (ATCC strain). Experiments were carried out according to EN 13727:2012 in quadruplicate under dirty conditions. The five evaluated SDCs were based on alcohol and an amphoteric substance (AAS), an oxygen-releaser (OR), surface-active substances (SAS), or surface-active-substances plus aldehydes (SASA; two formulations). Bactericidal concentrations of SDCs were determined at two different contact times. Efficacy was defined as a log10 ≥ 5 reduction in bacterial cell count. Results SDCs based on AAS, OR, and SAS were effective against all six species irrespective of the degree of multi-resistance. The SASA formulations were effective against the bacteria irrespective of degree of multi-resistance except for one of the four P. aeruginosa isolates (VIM-1). We found no general correlation between SDC efficacy and degree of antibiotic resistance. Conclusions SDCs were generally effective against gram-negative bacteria with and without multidrug resistance. SDCs are therefore suitable for surface disinfection in the immediate proximity of patients. Single bacterial isolates, however, might have reduced susceptibility to selected biocidal agents. PMID:24885029

Biodegradation of 2,4,6-tribromophenol during transport in fractured chalk.

PubMed

Arnon, Shai; Adar, Eilon; Ronen, Zeev; Nejidat, Ali; Yakirevich, Alexander; Nativ, Ronit

2005-02-01

The effect of physicochemical conditions (residence time, oxygen concentrations, and chalk characteristics) on the biodegradation of 2,4,6-tribromophenol (TBP) during transport was investigated in low-permeability fractured-chalk cores. Long-term (approximately 600 d) biodegradation experiments were conducted in two cores (approximately 21 cm diameter, 31 and 44 cm long, respectively), intersected by a natural fracture. TBP was used as a model contaminant and as the sole carbon source for aerobic microbial activity. Bacterial isolates were recovered and identified by both Biolog identification kit and 16S rDNA sequences from batch enrichment cultures. One of the strains, with 98% similarity (based on the 16S rDNA data) to Achromobacter xylosoxidans, was shown to have the ability to degrade TBP in the presence of chalk. The decrease in TBP concentration along the fracture due to biodegradation was not affected by reducing the residence time from 49 to 8 min. In contrast, adding oxygen to the water at the inlet and increasing the flow rates improved TBP removal. Although the matrix pore-size distribution limits microbial activity to the fracture void, the chalk appears to provide an excellent environment for biodegradation activity. Approximately 90% of TBP removal occurred within 10 cm of the TBP source, indicating that in-situ bioremediation can be used to remove organic contaminants in low-permeability fractured rocks if nutrient-delivery pathways within the aquifer are secured.

Soil bacteria showing a potential of chlorpyrifos degradation and plant growth enhancement.

PubMed

Akbar, Shamsa; Sultan, Sikander

2016-01-01

Since 1960s, the organophosphate pesticide chlorpyrifos has been widely used for the purpose of pest control. However, given its persistence and toxicity towards life forms, the elimination of chlorpyrifos from contaminated sites has become an urgent issue. For this process bioremediation is the method of choice. Two bacterial strains, JCp4 and FCp1, exhibiting chlorpyrifos-degradation potential were isolated from pesticide contaminated agricultural fields. These isolates were able to degrade 84.4% and 78.6% of the initial concentration of chlorpyrifos (100mgL(-1)) within a period of only 10 days. Based on 16S rRNA sequence analysis, these strains were identified as Achromobacter xylosoxidans (JCp4) and Ochrobactrum sp. (FCp1). These strains exhibited the ability to degrade chlorpyrifos in sterilized as well as non-sterilized soils, and were able to degrade 93-100% of the input concentration (200mgkg(-1)) within 42 days. The rate of degradation in inoculated soils ranged from 4.40 to 4.76mg(-1)kg(-1)d(-1) with rate constants varying between 0.047 and 0.069d(-1). These strains also displayed substantial plant growth promoting traits such as phosphate solubilization, indole acetic acid production and ammonia production both in absence as well as in the presence of chlorpyrifos. However, presence of chlorpyrifos (100 and 200mgL(-1)) was found to have a negative effect on indole acetic acid production and phosphate solubilization with percentage reduction values ranging between 2.65-10.6% and 4.5-17.6%, respectively. Plant growth experiment demonstrated that chlorpyrifos has a negative effect on plant growth and causes a decrease in parameters such as percentage germination, plant height and biomass. Inoculation of soil with chlorpyrifos-degrading strains was found to enhance plant growth significantly in terms of plant length and weight. Moreover, it was noted that these strains degraded chlorpyrifos at an increased rate (5.69mg(-1)kg(-1)d(-1)) in planted soil. The

Endophytic Bacteria Improve Plant Growth, Symbiotic Performance of Chickpea (Cicer arietinum L.) and Induce Suppression of Root Rot Caused by Fusarium solani under Salt Stress.

PubMed

Egamberdieva, Dilfuza; Wirth, Stephan J; Shurigin, Vyacheslav V; Hashem, Abeer; Abd Allah, Elsayed F

2017-01-01

Salinity causes disturbance in symbiotic performance of plants, and increases susceptibility of plants to soil-borne pathogens. Endophytic bacteria are an essential determinant of cross-tolerance to biotic and abiotic stresses in plants. The aim of this study was to isolate non-rhizobial endophytic bacteria from the root nodules of chickpea ( Cicer arietinum L.), and to assess their ability to improve plant growth and symbiotic performance, and to control root rot in chickpea under saline soil conditions. A total of 40 bacterial isolates from internal root tissues of chickpea grown in salinated soil were isolated. Four bacterial isolates, namely Bacillus cereus NUU1 , Achromobacter xylosoxidans NUU2, Bacillus thuringiensis NUU3, and Bacillus subtilis NUU4 colonizing root tissue demonstrated plant beneficial traits and/or antagonistic activity against F. solani and thus were characterized in more detail. The strain B. subtilis NUU4 proved significant plant growth promotion capabilities, improved symbiotic performance of host plant with rhizobia, and promoted yield under saline soil as compared to untreated control plants under field conditions. A combined inoculation of chickpea with M. ciceri IC53 and B. subtilis NUU4 decreased H 2 O 2 concentrations and increased proline contents compared to the un-inoculated plants indicating an alleviation of adverse effects of salt stress. Furthermore, the bacterial isolate was capable to reduce the infection rate of root rot in chickpea caused by F. solani . This is the first report of F. solani causing root rot of chickpea in a salinated soil of Uzbekistan. Our findings demonstrated that the endophytic B. subtilis strain NUU4 provides high potentials as a stimulator for plant growth and as biological control agent of chickpea root rot under saline soil conditions. These multiple relationships could provide promising practical approaches to increase the productivity of legumes under salt stress.

Endophytic Bacteria Improve Plant Growth, Symbiotic Performance of Chickpea (Cicer arietinum L.) and Induce Suppression of Root Rot Caused by Fusarium solani under Salt Stress

PubMed Central

Egamberdieva, Dilfuza; Wirth, Stephan J.; Shurigin, Vyacheslav V.; Hashem, Abeer; Abd_Allah, Elsayed F.

2017-01-01

Salinity causes disturbance in symbiotic performance of plants, and increases susceptibility of plants to soil-borne pathogens. Endophytic bacteria are an essential determinant of cross-tolerance to biotic and abiotic stresses in plants. The aim of this study was to isolate non–rhizobial endophytic bacteria from the root nodules of chickpea (Cicer arietinum L.), and to assess their ability to improve plant growth and symbiotic performance, and to control root rot in chickpea under saline soil conditions. A total of 40 bacterial isolates from internal root tissues of chickpea grown in salinated soil were isolated. Four bacterial isolates, namely Bacillus cereus NUU1, Achromobacter xylosoxidans NUU2, Bacillus thuringiensis NUU3, and Bacillus subtilis NUU4 colonizing root tissue demonstrated plant beneficial traits and/or antagonistic activity against F. solani and thus were characterized in more detail. The strain B. subtilis NUU4 proved significant plant growth promotion capabilities, improved symbiotic performance of host plant with rhizobia, and promoted yield under saline soil as compared to untreated control plants under field conditions. A combined inoculation of chickpea with M. ciceri IC53 and B. subtilis NUU4 decreased H2O2 concentrations and increased proline contents compared to the un-inoculated plants indicating an alleviation of adverse effects of salt stress. Furthermore, the bacterial isolate was capable to reduce the infection rate of root rot in chickpea caused by F. solani. This is the first report of F. solani causing root rot of chickpea in a salinated soil of Uzbekistan. Our findings demonstrated that the endophytic B. subtilis strain NUU4 provides high potentials as a stimulator for plant growth and as biological control agent of chickpea root rot under saline soil conditions. These multiple relationships could provide promising practical approaches to increase the productivity of legumes under salt stress. PMID:29033922

Purification and synergistic antibacterial activity of arginine derived cyclic dipeptides, from Achromobacter sp. associated with a rhabditid entomopathogenic nematode against major clinically relevant biofilm forming wound bacteria

PubMed Central

Deepa, Indira; Kumar, Sasidharan N.; Sreerag, Ravikumar S.; Nath, Vishnu S.; Mohandas, Chellapan

2015-01-01

Skin and chronic wound infections caused by various pathogenic bacteria are an increasing and urgent health problem worldwide. In the present investigation ethyl acetate extract of an Achromobacter sp. associated with a Rhabditis entomopathogenic nematode (EPN), displayed promising antibacterial property and was further purified by silica gel column chromatography to get three different cyclic dipeptides (CDPs). Based on the spectral data and Marfey's analyses, the CDPs were identified as cyclo(D-Leu-D-Arg) (1), cyclo(L-Trp-L-Arg) (2), and cyclo(D-Trp-D-Arg) (3), respectively. Three CDPs were active against all the 10 wound associated bacteria tested. The significant antibacterial activity was recorded by CDP 3, and highest activity of 0.5 μg/ml was recorded against Staphylococcus aureus and Pseudomonas aeruginosa. The synergistic antibacterial activities of CDPs and ampicillin were assessed using the checkerboard microdilution method. The results of the current study recorded that the combined effects of CDPs and ampicillin principally recorded synergistic activity. Interestingly, the combination of CDPs and ampicillin also recorded enhanced inhibition of biofilm formation by bacteria. Moreover, CDPs significantly stimulate the production of IL-10 and IL-4 (anti-inflammatory cytokines) by human peripheral blood mononuclear cells. CDPs do not make any significant effect on the production of pro-inflammatory cytokines like TNF-α. The three CDPs have been studied for their effect on intracellular S. aureus in murine macrophages (J774) using 24 h exposure to 0.5X, 1X, and 2X MIC concentrations. Significant decrease in intracellular S. aureus burden was recorded by CDPs. CDPs also recorded no cytotoxicity toward FS normal fibroblast, VERO, and L231 normal lung epithelial cell lines. Antimicrobial activity of the arginine containing CDPs against the wound associated bacteria is reported here for the first. Moreover, this is also the first report on the production of

Bioremediation assessment of diesel-biodiesel-contaminated soil using an alternative bioaugmentation strategy.

PubMed

Colla, Tatiana Simonetto; Andreazza, Robson; Bücker, Francielle; de Souza, Marcela Moreira; Tramontini, Letícia; Prado, Gerônimo Rodrigues; Frazzon, Ana Paula Guedes; Camargo, Flávio Anastácio de Oliveira; Bento, Fátima Menezes

2014-02-01

This study investigated the effectiveness of successive bioaugmentation, conventional bioaugmentation, and biostimulation of biodegradation of B10 in soil. In addition, the structure of the soil microbial community was assessed by polymerase chain reaction-denaturing gradient gel electrophoresis. The consortium was inoculated on the initial and the 11th day of incubation for successive bioaugmentation and only on the initial day for bioaugmentation and conventional bioaugmentation. The experiment was conducted for 32 days. The microbial consortium was identified based on sequencing of 16S rRNA gene and consisted as Pseudomonas aeruginosa, Achromobacter xylosoxidans, and Ochrobactrum intermedium. Nutrient introduction (biostimulation) promoted a positive effect on microbial populations. The results indicate that the edaphic community structure and dynamics were different according to the treatments employed. CO2 evolution demonstrated no significant difference in soil microbial activity between biostimulation and bioaugmentation treatments. The total petroleum hydrocarbon (TPH) analysis indicated a biodegradation level of 35.7 and 32.2 % for the biostimulation and successive bioaugmentation treatments, respectively. Successive bioaugmentation displayed positive effects on biodegradation, with a substantial reduction in TPH levels.

Metagenomics workflow analysis of endophytic bacteria from oil palm fruits

NASA Astrophysics Data System (ADS)

Tanjung, Z. A.; Aditama, R.; Sudania, W. M.; Utomo, C.; Liwang, T.

2017-05-01

Next-Generation Sequencing (NGS) has become a powerful sequencing tool for microbial study especially to lead the establishment of the field area of metagenomics. This study described a workflow to analyze metagenomics data of a Sequence Read Archive (SRA) file under accession ERP004286 deposited by University of Sao Paulo. It was a direct sequencing data generated by 454 pyrosequencing platform originated from oil palm fruits endophytic bacteria which were cultured using oil-palm enriched medium. This workflow used SortMeRNA to split ribosomal reads sequence, Newbler (GS Assembler and GS Mapper) to assemble and map reads into genome reference, BLAST package to identify and annotate contigs sequence, and QualiMap for statistical analysis. Eight bacterial species were identified in this study. Enterobacter cloacae was the most abundant species followed by Citrobacter koseri, Seratia marcescens, Latococcus lactis subsp. lactis, Klebsiella pneumoniae, Citrobacter amalonaticus, Achromobacter xylosoxidans, and Pseudomonas sp. respectively. All of these species have been reported as endophyte bacteria in various plant species and each has potential as plant growth promoting bacteria or another application in agricultural industries.

Biotransformation of arsenite and bacterial aox activity in drinking water produced from surface water of floating houses: Arsenic contamination in Cambodia.

PubMed

Chang, Jin-Soo

2015-11-01

The potential arsenite bioteansformation activity of arsenic was investigated by examining bacterial arsenic arsenite-oxidizing gene such as aoxS, aoxR, aoxA, aoxB, aoxC, and aoxD in high arsenic-contaminated drinking water produced from the surface water of floating houses. There is a biogeochemical cycle of activity involving arsenite oxidase aox system and the ars (arsenic resistance system) gene operon and aoxR leader gene activity in Alcaligenes faecalis SRR-11 and aoxS leader gene activity in Achromobacter xylosoxidans TSL-66. Batch experiments showed that SRR-11 and TSL-66 completely oxidized 1 mM of As (III) to As (V) within 35-40 h. The leaders of aoxS and aoxR are important for gene activity, and their effects in arsenic bioremediation and mobility in natural water has a significant ecological role because it allows arsenite oxidase in bacteria to control the biogeochemical cycle of arsenic-contaminated drinking water produced from surface water of floating houses. Copyright © 2015 Elsevier Ltd. All rights reserved.

MALDI-TOF Mass Spectrometry: A Powerful Tool for Clinical Microbiology at Hôpital Principal de Dakar, Senegal (West Africa)

PubMed Central

Lo, Cheikh I.; Fall, Bécaye; Sambe-Ba, Bissoume; Diawara, Silman; Gueye, Mamadou W.; Mediannikov, Oleg; Sokhna, Cheikh; Faye, Ngor; Diemé, Yaya; Wade, Boubacar; Raoult, Didier; Fenollar, Florence

2015-01-01

Our team in Europe has developed the routine clinical laboratory identification of microorganisms by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry (MS). To evaluate the utility of MALDI-TOF MS in tropical Africa in collaboration with local teams, we installed an apparatus in the Hôpital Principal de Dakar (Senegal), performed routine identification of isolates, and confirmed or completed their identification in France. In the case of discordance or a lack of identification, molecular biology was performed. Overall, 153/191 (80.1%) and 174/191 (91.1%) isolates yielded an accurate and concordant identification for the species and genus, respectively, with the 2 different MALDI-TOF MSs in Dakar and Marseille. The 10 most common bacteria, representing 94.2% of all bacteria routinely identified in the laboratory in Dakar (Escherichia coli, Klebsiella pneumoniae, Streptococcus agalactiae, Acinetobacter baumannii, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus haemolyticus, Enterobacter cloacae, Enterococcus faecalis, and Staphylococcus epidermidis) were accurately identified with the MALDI-TOF MS in Dakar. The most frequent misidentification in Dakar was at the species level for Achromobacter xylosoxidans, which was inaccurately identified as Achromobacter denitrificans, and the bacteria absent from the database, such as Exiguobacterium aurientacum or Kytococcus schroeteri, could not be identified. A few difficulties were observed with MALDI-TOF MS for Bacillus sp. or oral streptococci. 16S rRNA sequencing identified a novel bacterium, “Necropsobacter massiliensis.” The robust identification of microorganisms by MALDI-TOF MS in Dakar and Marseille demonstrates that MALDI-TOF MS can be used as a first-line tool in clinical microbiology laboratories in tropical countries. PMID:26716681

Isolation of bacterial strains able to degrade biphenyl, diphenyl ether and the heat transfer fluid used in thermo-solar plants.

PubMed

Blanco-Moreno, Rafael; Sáez, Lara P; Luque-Almagro, Víctor M; Roldán, M Dolores; Moreno-Vivián, Conrado

2017-03-25

Thermo-solar plants use eutectic mixtures of diphenyl ether (DE) and biphenyl (BP) as heat transfer fluid (HTF). Potential losses of HTF may contaminate soils and bioremediation is an attractive tool for its treatment. DE- or BP-degrading bacteria are known, but up to now bacteria able to degrade HTF mixture have not been described. Here, five bacterial strains which are able to grow with HTF or its separate components DE and BP as sole carbon sources have been isolated, either from soils exposed to HTF or from rhizospheric soils of plants growing near a thermo-solar plant. The organisms were identified by 16S rRNA gene sequencing as Achromobacter piechaudii strain BioC1, Pseudomonas plecoglossicida strain 6.1, Pseudomonas aeruginosa strains HBD1 and HBD3, and Pseudomonas oleovorans strain HBD2. Activity of 2,3-dihydroxybiphenyl dioxygenase (BphC), a key enzyme of the biphenyl upper degradation pathway, was detected in all isolates. Pseudomonas strains almost completely degraded 2000ppm HTF after 5-day culture, and even tolerated and grew in the presence of 150,000ppm HTF, being suitable candidates for in situ soil bioremediation. Degradation of both components of HTF is of particular interest since in the DE-degrader Sphingomonas sp. SS3, growth on DE or benzoate was strongly inhibited by addition of BP. Copyright © 2016 Elsevier B.V. All rights reserved.

Characterization and pathogenicity assessment of gut-associated microbes of muga silkworm Antheraea assamensis Helfer (Lepidoptera: Saturniidae).

PubMed

Haloi, Kishor; Kalita, Moni Kankana; Nath, Ramesh; Devi, Dipali

2016-07-01

Antheraea assamensis Helfer (muga silkworm) is an economically important endemic insect species of North Eastern Region of India. The silkworm is often susceptible to infection by pathogenic bacteria, leads to a disease commonly known as flacherie which causes 40% loss per annum to the silk industry. In this study, we have reported isolation, characterization and pathogenicity assessment of gut-associated bacteria of healthy and diseased muga silkworms. Thirty five bacterial isolates were screened from the gut of healthy and diseased silkworms by morphological observation and biochemical tests. 11 and 5 strains from healthy and diseased silkworm respectively were identified by 16S rRNA gene sequencing and analyzed. Pseudomonas aeruginosa (DRK1), Ornithinibacillus bavariensis (DRK2), Achromobacter xylosoxidans (KH3) and Staphylococcus aureus (FLG1) strains were commonly found in healthy as well as diseased larvae whereas, Bacillus thuringiensis (MK1) was found only in diseased larvae. Survivability analysis was performed with the identified strains by injection and oral administration (10(4)CFU/ml). The immune response of the silkworm against the pathogen was also studied by phenoloxidase and lysozyme enzyme activity assay, total and differential hemocyte count and phagocytic activity of hemocytes. It was observed that S. aureus, P. aeruginosa and B. thuringiensis significantly reduced the survivability of silkworm (p<0.001) hence found highly pathogenic. The lethal concentrations (LC50) values of the pathogenic strains were calculated at different time intervals (24, 48, 72 and 96h) within the range from 1.38×10(2) to 3.63×10(7)CFU/ml. The pathogenic groups demonstrated inhibition of phenoloxidase activity and decreased in total hemocyte count after 48h of infection. However, the lysozyme activity increased significantly in the pathogenic groups compared to the control (p<0.05). Granulocytes and plasmatocytes showed phagocytosis whereas; other types of cells did

Impact of polymicrobial biofilms in catheter-associated urinary tract infections.

PubMed

Azevedo, Andreia S; Almeida, Carina; Melo, Luís F; Azevedo, Nuno F

2017-08-01

Recent reports have demonstrated that most biofilms involved in catheter-associated urinary tract infections are polymicrobial communities, with pathogenic microorganisms (e.g. Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae) and uncommon microorganisms (e.g. Delftia tsuruhatensis, Achromobacter xylosoxidans) frequently co-inhabiting the same urinary catheter. However, little is known about the interactions that occur between different microorganisms and how they impact biofilm formation and infection outcome. This lack of knowledge affects CAUTIs management as uncommon bacteria action can, for instance, influence the rate at which pathogens adhere and grow, as well as affect the overall biofilm resistance to antibiotics. Another relevant aspect is the understanding of factors that drive a single pathogenic bacterium to become prevalent in a polymicrobial community and subsequently cause infection. In this review, a general overview about the IMDs-associated biofilm infections is provided, with an emphasis on the pathophysiology and the microbiome composition of CAUTIs. Based on the available literature, it is clear that more research about the microbiome interaction, mechanisms of biofilm formation and of antimicrobial tolerance of the polymicrobial consortium are required to better understand and treat these infections.

New strains of oil-degrading microorganisms for treating contaminated soils and wastes

NASA Astrophysics Data System (ADS)

Muratova, A. Yu; Panchenko, L. V.; Semina, D. V.; Golubev, S. N.; Turkovskaya, O. V.

2018-01-01

Two new strains Achromobacter marplatensis101n and Acinetobacter sp. S-33, capable of degrading 49 and 46% of oil within 7 days were isolated, identified, and characterized. The application of A. marplatensis 101n in combination with ammonium nitrate (100 mg·kg-1) for 30 days of cultivation resulted in the degradation of 49% of the initial total petroleum hydrocarbon content (274 g·kg-1) in the original highly acid (pH 4.9) oil-contaminated waste. Up to 30% of oil sludge added to a liquid mineral medium at a concentration of 15% was degraded after 10 days of cultivation of A. marplatensis 101n. Application of yellow alfalfa (Medicago falcata L.) plants with Acinetobacter sp. S-33 for bioremediation of oil-sludge-contaminated soil improved the quality of cleanup in comparison with the bacterium- or plant-only treatment. Inoculation of Acinetobacter sp. S-33 increased the growth of both roots and shoots by more than 40%, and positively influenced the soil microflora. We conclude that the new oil-degrading strains, Acinetobacter sp. S-33 and A. marplatensis 101n, can serve as the basis for new bioremediation agents for the treatment of oil contaminated soils and waste.

RELATIONSHIP BETWEEN CELL SURFACE PROPERTIES AND TRANSPORT OF BACTERIA THROUGH SOIL

EPA Science Inventory

A study was conducted to relate the properties of Enterobacter, Pseudomonas, Bacillus, Achromobacter, Flavobacterium, and Arthrobacter strains to their transport with water moving through soil. the bacteria differed markedly in their extent of transport; their hydrophobicity, as...

The Completely Sequenced Plasmid pEST4011 Contains a Novel IncP1 Backbone and a Catabolic Transposon Harboring tfd Genes for 2,4-Dichlorophenoxyacetic Acid Degradation

PubMed Central

Vedler, Eve; Vahter, Merle; Heinaru, Ain

2004-01-01

The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D)-degrading bacterium Achromobacter xylosoxidans subsp. denitrificans strain EST4002 contains plasmid pEST4011. This plasmid ensures its host a stable 2,4-D+ phenotype. We determined the complete 76,958-bp nucleotide sequence of pEST4011. This plasmid is a deletion and duplication derivative of pD2M4, the 95-kb highly unstable laboratory ancestor of pEST4011, and was self-generated during different laboratory manipulations performed to increase the stability of the 2,4-D+ phenotype of the original strain, strain D2M4(pD2M4). The 47,935-bp catabolic region of pEST4011 forms a transposon-like structure with identical copies of the hybrid insertion element IS1071::IS1471 at the two ends. The catabolic regions of pEST4011 and pJP4, the best-studied 2,4-D-degradative plasmid, both contain homologous, tfd-like genes for complete 2,4-D degradation, but they have little sequence similarity other than that. The backbone genes of pEST4011 are most similar to the corresponding genes of broad-host-range self-transmissible IncP1 plasmids. The backbones of the other three IncP1 catabolic plasmids that have been sequenced (the 2,4-D-degradative plasmid pJP4, the haloacetate-catabolic plasmid pUO1, and the atrazine-catabolic plasmid pADP-1) are nearly identical to the backbone of R751, the archetype plasmid of the IncP1 β subgroup. We show that despite the overall similarity in plasmid organization, the pEST4011 backbone is sufficiently different (51 to 86% amino acid sequence identity between individual backbone genes) from the backbones of members of the three IncP1 subgroups (the α, β, and γ subgroups) that it belongs to a new IncP1subgroup, the δ subgroup. This conclusion was also supported by a phylogenetic analysis of the trfA2, korA, and traG gene products of different IncP1 plasmids. PMID:15489427

Proton-coupled electron transfer in the catalytic cycle of Alcaligenes xylosoxidans copper-dependent nitrite reductase.

PubMed

Leferink, Nicole G H; Han, Cong; Antonyuk, Svetlana V; Heyes, Derren J; Rigby, Stephen E J; Hough, Michael A; Eady, Robert R; Scrutton, Nigel S; Hasnain, S Samar

2011-05-17

We demonstrated recently that two protons are involved in reduction of nitrite to nitric oxide through a proton-coupled electron transfer (ET) reaction catalyzed by the blue Cu-dependent nitrite reductase (Cu NiR) of Alcaligenes xylosoxidans (AxNiR). Here, the functionality of two putative proton channels, one involving Asn90 and the other His254, is studied using single (N90S, H254F) and double (N90S--H254F) mutants. All mutants studied are active, indicating that protons are still able to reach the active site. The H254F mutation has no effect on the catalytic activity, while the N90S mutation results in ~70% decrease in activity. Laser flash-photolysis experiments show that in H254F and wild-type enzyme electrons enter at the level of the T1Cu and then redistribute between the two Cu sites. Complete ET from T1Cu to T2Cu occurs only when nitrite binds at the T2Cu site. This indicates that substrate binding to T2Cu promotes ET from T1Cu, suggesting that the enzyme operates an ordered mechanism. In fact, in the N90S and N90S--H254F variants, where the T1Cu site redox potential is elevated by ∼60 mV, inter-Cu ET is only observed in the presence of nitrite. From these results it is evident that the Asn90 channel is the main proton channel in AxNiR, though protons can still reach the active site if this channel is disrupted. Crystallographic structures provide a clear structural rationale for these observations, including restoration of the proton delivery via a significant movement of the loop connecting the T1Cu ligands Cys130 and His139 that occurs on binding of nitrite. Notably, a role for this loop in facilitating interaction of cytochrome c(551) with Cu NiR has been suggested previously based on a crystal structure of the binary complex.

Diagnosis of biofilm infections in cystic fibrosis patients.

PubMed

Høiby, Niels; Bjarnsholt, Thomas; Moser, Claus; Jensen, Peter Østrup; Kolpen, Mette; Qvist, Tavs; Aanaes, Kasper; Pressler, Tanja; Skov, Marianne; Ciofu, Oana

2017-04-01

Chronic Pseudomonas aeruginosa biofilm lung infection in cystic fibrosis patients is the best described biofilm infection in medicine. The initial focus can be the paranasal sinuses and then follows repeated colonization and infection of the lungs by aspiration. The matrix of the biofilms is dominated by alginate and the pathogenesis of tissue damage is immune complex-mediated chronic inflammation dominated by polymorphonuclear leukocytes and their products (DNA, oxygen radicals and proteases). The P. aeruginosa biofilm infection can be diagnosed by microscopy of lung tissue, sputum and mucus from the paranasal sinuses, where aggregates of the bacteria are found surrounded by the abundant alginate matrix. Specific PNA-FISH probes can be used to identify P. aeruginosa and other pathogens in situ in the biofilms. Growth of mucoid colonies from the locations mentioned above is also diagnostic for biofilm infection. Rise of specific anti-P. aeruginosa antibodies is likewise diagnostic, IgG in serum in case of lung infection, sIgA in saliva or nasal secretions in case of paranasal sinus infection. Similar approaches have been developed to diagnose chronic biofilm infections in cystic fibrosis caused by other pathogens e.g., Stenotrophomonas, Burkholderia multivorans, Achromobacter xylosoxidans and Mycobacterium abscessus complex. © 2017 APMIS. Published by John Wiley & Sons Ltd.

Biodegradation of phenol and benzene by endophytic bacterial strains isolated from refinery wastewater-fed Cannabis sativa.

PubMed

Iqbal, Aneela; Arshad, Muhammad; Hashmi, Imran; Karthikeyan, Raghupathy; Gentry, Terry J; Schwab, Arthur Paul

2017-06-13

The presence of benzene and phenol in the environment can lead to serious health effects in humans and warrant development of efficient cleanup strategies. The aim of the present work was to assess the potential of indigenous endophytic bacterial strains to degrade benzene and phenol. Seven strains were successfully isolated from Cannabis sativa plants irrigated with oil refinery wastewater. Molecular characterization was performed by 16S rRNA gene sequencing. Phenol was biodegraded almost completely with Achromobacter sp. (AIEB-7), Pseudomonas sp. (AIEB-4), and Alcaligenes sp. (AIEB-6) at 250, 500, and 750 mg L -1 ; however, the degradation was only 81%, 72%, and 69%, respectively, when exposed to 1000 mg L -1 . Bacillus sp. (AIEB-1), Enterobacter sp. (AIEB-3), and Acinetobacter sp. (AIEB-2) degraded benzene significantly at 250, 500, and 750 mg L -1 . However, these strains showed 80%, 72%, and 68% benzene removal at 1000 mg L -1 exposure, respectively. Rates of degradation could be modeled with first-order kinetics with rate constant values of 1.86 × 10 -2 for Pseudomonas sp. (AIEB-4) and 1.80 × 10 -2  h -1 for Bacillus sp. (AIEB-1) and half-lives of 1.5 and 1.6 days, respectively. These results establish a foundation for further testing of the phytoremediation of hydrocarbon-contaminated soils in the presence of these endophytic bacteria.

Endoglucanase and xylanase production by Bacillus sp. AR03 in co-culture.

PubMed

Hero, Johan S; Pisa, José H; Perotti, Nora I; Romero, Cintia M; Martínez, María A

2017-07-03

The behavior of three isolates retrieved from different cellulolytic consortia, Bacillus sp. AR03, Paenibacillus sp. AR247 and Achromobacter sp. AR476-2, were examined individually and as co-cultures in order to evaluate their ability to produce extracellular cellulases and xylanases. Utilizing a peptone-based medium supplemented with carboxymethyl cellulose (CMC), an increase estimation of 1.30 and 1.50 times was obtained by the co-culture containing the strains AR03 and AR247, with respect to enzyme titles registered by their individual cultivation. On the contrary, the extracellular enzymatic production decreased during the co-cultivation of strain AR03 with the non-cellulolytic Achromobacter sp. AR476-2. The synergistic behavior observed through the combined cultivation of the strains AR03 and AR247 might be a consequence of the consumption by Paenibacillus sp. AR247 of the products of the CMC hydrolysis (i.e., cellobiose and/or cello-oligosaccharides), which were mostly generated by the cellulase producer Bacillus sp. AR03. The effect observed could be driven by the requirement to fulfill the nutritional supply from both strains on the substrate evaluated. These results would contribute to a better description of the degradation of the cellulose fraction of the plant cell walls in nature, expected to an efficient utilization of renewable sources.

Hypertonic Saline as a Useful Tool for Sputum Induction and Pathogen Detection in Cystic Fibrosis.

PubMed

Ferreira, Adriana Carolina Marques; Marson, Fernando Augusto Lima; Cohen, Milena Antonelli; Bertuzzo, Carmen Silvia; Levy, Carlos Emilio; Ribeiro, Antonio Fernando; Ribeiro, Jose Dirceu

2017-08-01

The aim of this study was to compare the qualitative and semi-quantitative detection of pathogens in the airway secretions of patients with cystic fibrosis (CF) and the sputum induction capacity before and after inhalation of 7% hypertonic saline solution (HSS). The study enrolled 64 patients with CF. Airway secretions were collected from all enrolled patients with CF before and after inhalation of 7% HSS, and the samples were screened for pathogens. Inhalation of 7% HSS increased the probability of producing sputum from 36 to 52% (p = 0.002) in children with CF. The effect was most in children under 11 years. Inhalation of 7% HSS improved qualitative pathogen identification (p = 0.008). Inhalation of 7% HSS increased the mucoid Pseudomonas aeruginosa (p = 0.002) and non-mucoid P. aeruginosa in the semi-quantitative analysis (p = 0.035). Four new pathogens (Aspergillus fumigatus, Achromobacter xylosoxidans, Ochrobactrum anthropi, and Elizabethkingia meningoseptica) were identified in the sputum samples collected from the airways of patients with CF following 7% HSS. Inhalation of 7% HSS increased sputum production and pathogen identification in children with CF. The inhalation of 7% HSS was feasible and should be implemented for routine pathogen detection in the airways of patients with CF, particularly in those patients who do not produce sputum.

A strategic approach for the design and operation of two-phase partitioning bioscrubbers for the treatment of volatile organic compounds.

PubMed

Yeom, Sung Ho; Daugulis, Andrew J; Nielsen, David R

2010-01-01

A strategic approach for the design of two-phase partitioning bioscrubbers (TPPBs) has been formulated using, as a basis, a re-evaluation of extensive literature data available for the degradation of benzene by Achromobacter xylosoxidans Y234 in TPPBs with n-hexadecane as the partitioning phase. Using a previously determined maintenance coefficient for benzene, we determined that an inlet benzene loading rate of 100 mg/h requires 5,928 mg cell mass at biological steady state and 243.0 mg O(2) /h. The total oxygen-transfer rates (TOTRs) into the TPPB increased by 83.5% with 33.3% of organic phase compared with a single aqueous phase and were significantly influenced by gas flow rate, whereas agitation has a minor affect. The fraction of organic phase used was suggested to be the primary parameter with which the TOTR into the TPPB may be altered. Although the presence of an organic solvent in the TPPB remarkably increased the TOTR, the total benzene transfer rate into the TPPB remained largely insensitive due to the intrinsic low Henry's law constant (or relatively high solubility) of benzene in water. Finally, we have integrated the elements of this analysis into a set of heuristic criteria that can serve as a guideline for the design of TPPB systems for future volatile organic compound treatment applications. Copyright © 2010 American Institute of Chemical Engineers (AIChE).

Plasmid-mediated bioaugmentation of sequencing batch reactors for enhancement of 2,4-dichlorophenoxyacetic acid removal in wastewater using plasmid pJP4.

PubMed

Tsutsui, Hirofumi; Anami, Yasutaka; Matsuda, Masami; Hashimoto, Kurumi; Inoue, Daisuke; Sei, Kazunari; Soda, Satoshi; Ike, Michihiko

2013-06-01

Plasmid-mediated bioaugmentation was demonstrated using sequencing batch reactors (SBRs) for enhancing 2,4-dichlorophenoxyacetic acid (2,4-D) removal by introducing Cupriavidus necator JMP134 and Escherichia coli HB101 harboring 2,4-D-degrading plasmid pJP4. C. necator JMP134(pJP4) can mineralize and grow on 2,4-D, while E. coli HB101(pJP4) cannot assimilate 2,4-D because it lacks the chromosomal genes to degrade the intermediates. The SBR with C. necator JMP134(pJP4) showed 100 % removal against 200 mg/l of 2,4-D just after its introduction, after which 2,4-D removal dropped to 0 % on day 7 with the decline in viability of the introduced strain. The SBR with E. coli HB101(pJP4) showed low 2,4-D removal, i.e., below 10 %, until day 7. Transconjugant strains of Pseudomonas and Achromobacter isolated on day 7 could not grow on 2,4-D. Both SBRs started removing 2,4-D at 100 % after day 16 with the appearance of 2,4-D-degrading transconjugants belonging to Achromobacter, Burkholderia, Cupriavidus, and Pandoraea. After the influent 2,4-D concentration was increased to 500 mg/l on day 65, the SBR with E. coli HB101(pJP4) maintained stable 2,4-D removal of more than 95 %. Although the SBR with C. necator JMP134(pJP4) showed a temporal depression of 2,4-D removal of 65 % on day 76, almost 100 % removal was achieved thereafter. During this period, transconjugants isolated from both SBRs were mainly Achromobacter with high 2,4-D-degrading capability. In conclusion, plasmid-mediated bioaugmentation can enhance the degradation capability of activated sludge regardless of the survival of introduced strains and their 2,4-D degradation capacity.

Thermotemporal dynamics of contaminant bacteria and antimicrobials in extended porcine semen.

PubMed

Althouse, G C; Pierdon, M S; Lu, K G

2008-11-01

Bacterial contamination of extended porcine semen has been associated with deleterious effects on both semen quality and sow fertility. Retrospective, prospective and in vitro studies were performed to delineate the prevalence and behavior of certain bacterial contaminants in extended semen, and antimicrobial pharmacodynamics in various semen diluents. Retrospective review of extended semen samples submitted from North American boar studs for microbiological screening at the University of Pennsylvania Reference Andrology Laboratory in 2005 and 2006 yielded bacteriospermia prevalence rates of 17% (144/832) and 26% (256/984), respectively. In a prospective study of regional boar studs, of 91 extended semen samples tested over 1-y, 29% were positive for bacteriospermia. Retrospective and prospective studies both showed that the preponderance of contaminant positive samples occurred during the fall months (P<0.05). To better understand behavior of select contaminant bacteria, generation intervals were determined for Serratia marcescens (SM) and Achromobacter xylosoxidans (AX) at 16, 22 and 37 degrees C. Generation times were temperature-dependent, with intervals decreasing two- to four-fold as incubation temperature increased. Growth patterns for SM, AX and Burkholderia cepacia were evaluated in various semen diluents. The different diluents exhibited constant or episodic patterns of growth within and among bacteria throughout the 5-d test period. Kill-time kinetics at 37 degrees C of several genera of bacteria in four semen diluents containing amoxicillin, gentamicin, tylosin, and lincomycin/spectinomycin (single drug or combination) ranged from 75 to over 360min, and was highly dependent (P<0.05) upon both type of bacteria and semen diluent.

TSCA Environmental Release Application (TERA) for Alcaligenes xylosoxidans subspecies denitrificans strain AL6.1

EPA Pesticide Factsheets

TERA submitted by University of California, Riverside and given the tracking designation of R-03-0001. The microorganism has been modified to carry a coding sequence of DsRed for expressing a red fluorescent protein.

Characterization of arsenic resistant bacteria from arsenic rich groundwater of West Bengal, India.

PubMed

Sarkar, Angana; Kazy, Sufia K; Sar, Pinaki

2013-03-01

Sixty-four arsenic (As) resistant bacteria isolated from an arsenic rich groundwater sample of West Bengal were characterized to investigate their potential role in subsurface arsenic mobilization. Among the isolated strains predominance of genera Agrobacterium/Rhizobium, Ochrobactrum and Achromobacter which could grow chemolitrophically and utilize arsenic as electron donor were detected. Higher tolerance to As(3+) [maximum tolerable concentration (MTC): ≥10 mM], As(5+) (MTC: ≥100 mM) and other heavy metals like Cu(2+), Cr(2+), Ni(2+) etc. (MTC: ≥10 mM), presence of arsenate reductase and siderophore was frequently observed among the isolates. Ability to produce arsenite oxidase and phosphatase enzyme was detected in 50 and 34 % of the isolates, respectively. Although no direct correlation among taxonomic identity of bacterial strains and their metabolic abilities as mentioned above was apparent, several isolates affiliated to genera Ochrobactrum, Achromobacter and unclassified Rhizobiaceae members were found to be highly resistant to As(3+) and As(5+) and positive for all the test properties. Arsenate reductase activity was found to be conferred by arsC gene, which in many strains was coupled with arsenite efflux gene arsB as well. Phylogenetic incongruence between the 16S rRNA and ars genes lineages indicated possible incidence of horizontal gene transfer for ars genes. Based on the results we propose that under the prevailing low nutrient condition inhabitant bacteria capable of using inorganic electron donors play a synergistic role wherein siderophores and phosphatase activities facilitate the release of sediment bound As(5+), which is subsequently reduced by arsenate reductase resulting into the mobilization of As(3+) in groundwater.

Microbiology of airway disease in a cohort of patients with Cystic Fibrosis

PubMed Central

Lambiase, Antonietta; Raia, Valeria; Pezzo, Mariassunta Del; Sepe, Angela; Carnovale, Vincenzo; Rossano, Fabio

2006-01-01

Background Recent reports document an increasing incidence of new Gram-negative pathogens such as Stenotrophomonas maltophilia and Alcaligenes xylosoxidans isolated from patients with Cystic Fibrosis, along with an increase in common Gram-negative pathogens such as Pseudomonas aeruginosa and Burkholderia cepacia complex. Furthermore, the increase in multidrug-resistance of such organisms makes the therapeutic management of these patients more problematic. Therefore, careful isolation and identification, and accurate studies of susceptibility to antibiotics are critical for predicting the spread of strains, improving therapeutic measures and facilitating our understanding of the epidemiology of emerging pathogens. The first aim of this study was to determine the incidence and the prevalence of colonization by Gram-negative organisms isolated from respiratory samples of Cystic Fibrosis patients in the Regional Referral Cystic Fibrosis Centre of Naples; the second was to evaluate the spectrum of multidrug-resistance of these organisms. Methods Patients (n = 300) attending the Regional Cystic Fibrosis Unit were enrolled in this study over 3 years. Sputum was processed for microscopic tests and culture. An automated system, Phoenix (Becton Dickinson, Sparks, Maryland, USA), was used for phenotypic identification of all strains; the API 20 NE identification system (bioMérieux, Marcy l'Etoile, France) was used when the identification with the Phoenix system was inaccurate. A PCR-RFLP method was used to characterize the organisms in the Burkholderia cepacia complex. A chemosusceptibility test on microbroth dilutions (Phoenix) was used. Primary outcomes such as FEV1 were correlate with different pathogens. Results During the period of study, 40% of patients was infected by Pseudomonas aeruginosa, 7% by Burkholderia cepacia complex, 11% by Stenotrophomonas maltophilia and 7% by Alcaligenes xylosoxidans. Of the strains isolated, 460 were multidrug-resistant. Multiresistant

Screening and identification of aerobic denitrifiers

NASA Astrophysics Data System (ADS)

Shao, K.; Deng, H. M.; Chen, Y. T.; Zhou, H. J.; Yan, G. X.

2016-08-01

With the standards of the effluent quality more stringent, it becomes a quite serious problem for municipalities and industries to remove nitrogen from wastewater. Bioremediation is a potential method for the removal of nitrogen and other pollutants because of its high efficiency and low cost. Seven predominant aerobic denitrifiers were screened and characterized from the activated sludge in the CAST unit. Some of these strains removed 87% nitrate nitrogen at least. Based on their phenotypic and phylogenetic characteristics, the isolates were identified as the genera of Ralstonia, Achromobacter, Aeromonas and Enterobacter.

Role of Thiobacillus thioparus in the biodegradation of carbon disulfide in a biofilter packed with a recycled organic pelletized material.

PubMed

Prenafeta-Boldú, Francesc X; Rojo, Naiara; Gallastegui, Gorka; Guivernau, Miriam; Viñas, Marc; Elías, Ana

2014-07-01

This study reports the biodegradation of carbon disulfide (CS2) in air biofilters packed with a pelletized mixture of composted manure and sawdust. Experiments were carried out in two lab-scale (1.2 L) biofiltration units. Biofilter B was seeded with activated sludge enriched previously on CS2-degrading biomass under batch conditions, while biofilter A was left as a negative inoculation control. This inoculum was characterized by an acidic pH and sulfate accumulation, and contained Achromobacter xylosoxidans as the main putative CS2 biodegrading bacterium. Biofilter operation start-up was unsuccessfully attempted under xerophilic conditions and significant CS2 elimination was only achieved in biofilter A upon the implementation of an intermittent irrigation regime. Sustained removal efficiencies of 90-100 % at an inlet load of up to 12 g CS2 m(-3) h(-1) were reached. The CS2 removal in this biofilter was linked to the presence of the chemolithoautotrophic bacterium Thiobacillus thioparus, known among the relatively small number of species with a reported capacity of growing on CS2 as the sole energy source. DGGE molecular profiles confirmed that this microbe had become dominant in biofilter A while it was not detected in samples from biofilter B. Conventional biofilters packed with inexpensive organic materials are suited for the treatment of low-strength CS2 polluted gases (IL <12 g CS2 m(-3) h(-1)), provided that the development of the adequate microorganisms is favored, either upon enrichment or by inoculation. The importance of applying culture-independent techniques for microbial community analysis as a diagnostic tool in the biofiltration of recalcitrant compounds has been highlighted.

Distribution of microbial biomass and potential for anaerobic respiration in Hanford Site 300 Area subsurface sediment.

PubMed

Lin, Xueju; Kennedy, David; Peacock, Aaron; McKinley, James; Resch, Charles T; Fredrickson, James; Konopka, Allan

2012-02-01

Subsurface sediments were recovered from a 52-m-deep borehole cored in the 300 Area of the Hanford Site in southeastern Washington State to assess the potential for biogeochemical transformation of radionuclide contaminants. Microbial analyses were made on 17 sediment samples traversing multiple geological units: the oxic coarse-grained Hanford formation (9 to 17.4 m), the oxic fine-grained upper Ringold formation (17.7 to 18.1 m), and the reduced Ringold formation (18.3 to 52 m). Microbial biomass (measured as phospholipid fatty acids) ranged from 7 to 974 pmols per g in discrete samples, with the highest numbers found in the Hanford formation. On average, strata below 17.4 m had 13-fold less biomass than those from shallower strata. The nosZ gene that encodes nitrous oxide reductase (measured by quantitative real-time PCR) had an abundance of 5 to 17 relative to that of total 16S rRNA genes below 18.3 m and <5 above 18.1 m. Most nosZ sequences were affiliated with Ochrobactrum anthropi (97 sequence similarity) or had a nearest neighbor of Achromobacter xylosoxidans (90 similarity). Passive multilevel sampling of groundwater geochemistry demonstrated a redox gradient in the 1.5-m region between the Hanford-Ringold formation contact and the Ringold oxic-anoxic interface. Within this zone, copies of the dsrA gene and Geobacteraceae had the highest relative abundance. The majority of dsrA genes detected near the interface were related to Desulfotomaculum spp. These analyses indicate that the region just below the contact between the Hanford and Ringold formations is a zone of active biogeochemical redox cycling.

Distribution of Microbial Biomass and Potential for Anaerobic Respiration in Hanford Site 300 Area Subsurface Sediment

PubMed Central

Lin, Xueju; Kennedy, David; Peacock, Aaron; McKinley, James; Resch, Charles T.; Fredrickson, James

2012-01-01

Subsurface sediments were recovered from a 52-m-deep borehole cored in the 300 Area of the Hanford Site in southeastern Washington State to assess the potential for biogeochemical transformation of radionuclide contaminants. Microbial analyses were made on 17 sediment samples traversing multiple geological units: the oxic coarse-grained Hanford formation (9 to 17.4 m), the oxic fine-grained upper Ringold formation (17.7 to 18.1 m), and the reduced Ringold formation (18.3 to 52 m). Microbial biomass (measured as phospholipid fatty acids) ranged from 7 to 974 pmols per g in discrete samples, with the highest numbers found in the Hanford formation. On average, strata below 17.4 m had 13-fold less biomass than those from shallower strata. The nosZ gene that encodes nitrous oxide reductase (measured by quantitative real-time PCR) had an abundance of 5 to 17 relative to that of total 16S rRNA genes below 18.3 m and <5 above 18.1 m. Most nosZ sequences were affiliated with Ochrobactrum anthropi (97 sequence similarity) or had a nearest neighbor of Achromobacter xylosoxidans (90 similarity). Passive multilevel sampling of groundwater geochemistry demonstrated a redox gradient in the 1.5-m region between the Hanford-Ringold formation contact and the Ringold oxic-anoxic interface. Within this zone, copies of the dsrA gene and Geobacteraceae had the highest relative abundance. The majority of dsrA genes detected near the interface were related to Desulfotomaculum spp. These analyses indicate that the region just below the contact between the Hanford and Ringold formations is a zone of active biogeochemical redox cycling. PMID:22138990

[Uncommon non-fermenting Gram-negative rods as pathogens of lower respiratory tract infection].

PubMed

Juhász, Emese; Iván, Miklós; Pongrácz, Júlia; Kristóf, Katalin

2018-01-01

Glucose non-fermenting Gram-negative bacteria are ubiquitous environmental organisms. Most of them are identified as opportunistic, nosocomial pathogens in patients. Uncommon species are identified accurately, mainly due to the introduction of matrix-assisted laser desorption-ionization time of flight mass spectrometry (MALDI-TOF MS) in clinical microbiology practice. Most of these uncommon non-fermenting rods are isolated from lower respiratory tract samples. Their significance in lower respiratory tract infections, such as rules of their testing are not clarified yet. The aim of this study was to review the clinical microbiological features of these bacteria, especially their roles in lower respiratory tract infections and antibiotic treatment options. Lower respiratory tract samples of 3589 patients collected in a four-year period (2013-2016) were analyzed retrospectively at Semmelweis University (Budapest, Hungary). Identification of bacteria was performed by MALDI-TOF MS, the antibiotic susceptibility was tested by disk diffusion method. Stenotrophomonas maltophilia was revealed to be the second, whereas Acinetobacter baumannii the third most common non-fermenting rod in lower respiratory tract samples, behind the most common Pseudomonas aeruginosa. The total number of uncommon non-fermenting Gram-negative isolates was 742. Twenty-three percent of isolates were Achromobacter xylosoxidans. Beside Chryseobacterium, Rhizobium, Delftia, Elizabethkingia, Ralstonia and Ochrobactrum species, and few other uncommon species were identified among our isolates. The accurate identification of this species is obligatory, while most of them show intrinsic resistance to aminoglycosides. Resistance to ceftazidime, cefepime, piperacillin-tazobactam and carbapenems was frequently observed also. Ciprofloxacin, levofloxacin and trimethoprim-sulfamethoxazole were found to be the most effective antibiotic agents. Orv Hetil. 2018; 159(1): 23-30.

Phenotypic and Genetic Characterization of Carbapenemase and ESBLs Producing Gram-negative Bacteria (GNB) Isolated from Patients with Cystic Fibrosis (CF) in Tehran Hospitals

PubMed Central

Vali, Parisa; Shahcheraghi, Fereshteh; Seyfipour, Maryam; Zamani, Maryam Alsadat; Allahyar, Mohammad Reza; Feizabadi, Mohammad Mehdi

2014-01-01

Background: Cystic Fibrosis (CF) is an autosomal recessive genetic disorder in white populations caused by mutation in a gene that encodes Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) protein. Since frequent respiratory tract infections are the major problem in patients with CF, obligation to identify the causative bacteria and determining their antibiotic resistance pattern is crucial. The purpose of this project was to detect Gram-negative bacteria (GNB) isolated from sputa of CF patients and to determine their antibiotic resistance pattern. Materials and Methods: The sputum of 52 CF patients, treated as inpatients at hospitals in Tehran, was obtained between November 2011 and June 2012. Samples cultured in selective and non-selective media and GNB recognized by biochemical tests. Antimicrobial susceptibility testing to cephalosporins, aminoglycosides and carbapenems was performed by disk diffusion method and MICs of them were measured. For phenotypic detection of carbapenemase and ESBLs production, the Modified Hodge test, double disk synergy test and the combined disk methods were performed. Subsequently, the genes encoding the extended spectrum beta-lactamases (blaPER, blaCTX-M) and carbapenemases (blaIMP-1, blaGES, blaKPC, blaNDM, blaVIM-1, blaVIM-2, blaSPM, blaSIM) in Gram negative bacteria were targeted among the resistant isolates by using PCR. PFGE was used to determine any genetic relationship among the Pseudomonas aeruginosa isolated from these patients. Results: Fifty five GNB were isolated from 52 sputum samples including Pseudomonas aeruginosa, Klebsiella ozaenae, Alcaligenes xylosoxidans, Achromobacter denitrificans, Klebsiella pneumonia and Stenotrophomonas maltophilia. The rates of resistance to different antibiotic were as follows: cefixime (%80), ceftriaxone (%43), ceftazidime (%45) and meropenem (%7). The prevalence of genes encoding the ESBLs and Carbapenemases among the the phenotypically positive strains were as follows: bla

Screening of a microbial consortium for selective degradation of lignin from tree trimmings.

PubMed

Fang, Xiuxiu; Li, Qiumin; Lin, Yunqin; Lin, Xinlei; Dai, Yiqi; Guo, Zexiang; Pan, Dezhao

2018-04-01

To acquire microbial consortia with effectively precedent degradation of lignin, samples obtained from rotten trunks, rotten stumps and soil near it were screened and isolated after generations of subculture. The dynamic change illustrated that their community structures were affected by pH and tended to be stable after 6 days' cultivation. The desired one, named DM-1, was gained through successive cultivation for over 5 generations, whose high selectivity in lignin degradation was observed within 16 days' cultivation (SV = 2.78). Meanwhile, a remarkable reduction in the fiber crystallinity of tree trimmings (10.35%) resulted from the bio-degradation of DM-1, displayed a greater exposure of cellulose by selective removal of lignin. The diversity analysis of DM-1 was investigated by PCR amplification and 16S rDNA sequencing, indicated that mesorhizobium, cellulosimicrobium, pandoraea, achromobacter and stenotrophomones were the predominant genera. Furthermore, fungi (3 strains), bacteria (4 strains) and actinomycetes (5 strains) constituted 12 strains in total were gained by plate isolation from DM-1. Copyright © 2018 Elsevier Ltd. All rights reserved.

Natural Strain

NASA Technical Reports Server (NTRS)

Freed, Alan D.

1995-01-01

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

TSCA Environmental Release Application (TERA) for Alcaligenes xylosoxidans subspecies denitrificans strain AL6.1, R05-01

EPA Pesticide Factsheets

TERA submitted by the University of California, Riverside. The microorganism will be tested to determine its biology and behavior in vineyard ecosystems as part of a research program to prevent or cure Pierce's disease in grapes.

A Little Vacation on Mars: Mars Simulation Microbial Challenge Experiments

NASA Astrophysics Data System (ADS)

Boston, P.; Todd, P.; Van De Camp, J.; Northup, D.; Spilde, M.

2008-06-01

Communities of microbial organisms isolated from a variety of extreme environments were subjected to 1 to 5 weeks of simulated Martian environmental conditions using the Mars Environment Simulation Chamber at the Techshot, Inc. facility in Greenville, Indiana. The goal of the overall experiment program was to assess survival of test Earth organisms under Mars full spectrum sunlight, low-latitude daily temperature profile and various Mars-atmosphere pressures (~50 mbar to 500 mbar, 100% CO2) and low moisture content. Organisms surviving after 5 weeks at 100 mbar included those from gypsum surface fracture communities in a Permian aged evaporite basin, desert varnish on andesite lavas around a manganese mine, and iron and manganese oxidizing organisms isolated from two caves in Mew Mexico. Phylogenetic DNA analysis revealed strains of cyanobacteria, bacterial genera (present in all surviving communities) Asticacaulis, Achromobacter, Comamonas, Pantoea, Verrucomicrobium, Bacillus, Gemmatimonas, Actinomyces, and others. At least one microcolonial fungal strain from a desert varnish community and at least one strain from Utah survived simulations. Strains related to the unusual cave bacterial group Bacteroidetes are present in survivor communities that resist isolation into pure culture implying that their consortial relationships may be critical to their survival.

Natural Strain

NASA Technical Reports Server (NTRS)

Freed, Alan D.

1997-01-01

Logarithmic strain is the preferred measure of strain used by materials scientists, who typically refer to it as the "true strain." It was Nadai who gave it the name "natural strain," which seems more appropriate. This strain measure was proposed by Ludwik for the one-dimensional extension of a rod with length l. It was defined via the integral of dl/l to which Ludwik gave the name "effective specific strain." Today, it is after Hencky, who extended Ludwik's measure to three-dimensional analysis by defining logarithmic strains for the three principal directions.

Eiseniicola composti gen. nov., sp. nov., with antifungal activity against plant pathogenic fungi.

PubMed

Yasir, Muhammad; Aslam, Zubair; Song, Geun Cheol; Jeon, Che Ok; Chung, Young Ryun

2010-01-01

A Gram-negative, short rod-shaped bacterial strain, YC06271T, was isolated from the vermicompost (VC) collected at Masan, Korea and its taxonomic position was investigated by a polyphasic taxonomic approach. Strain YC06271T grew optimally at 28-30 degrees C and at pH 7.0-9.0. The 16S rRNA gene sequence of strain YC06271T was most closely related to members of the genera Bordetella (96.4-95.8 %), Achromobacter (96.0-95.7 %), Alcaligenes (96.0-94.2 %), Pusillimonas noertemannii (95.9 %), Pigmentiphaga (95.8-95.5 %) and less than 95.5 % similarity with the members of the other genera of the family Alcaligenaceae. Strain YC06271T contained ubiquinone-8 (Q-8) as the major respiratory quinone system and putrescine as the major polyamine. The major fatty acids of strain YC06271T were C16:1omega7c and/or C15:0 iso 2-OH and C16:0. The major polar lipids were phosphatidylglycerol and phosphatidylethanolamine. The G+C content of the genomic DNA was 55.4 mol%. Phylogenetic analysis, biochemical, chemotaxonomic and phenotypic characteristics strongly supported the differentiation of strain YC06271T from the validly published genera of the family Alcaligenaceae. Therefore, it is proposed that strain YC06271T represents a novel species within a novel genus, with the name Eiseniicola composti gen. nov., sp. nov. The type strain is YC06271T (= KCTC 22250T = DSM 21045T).

Highly stretchable miniature strain sensor for large dynamic strain measurement

DOE PAGES

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

2016-01-01

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

Demonstration test of burner liner strain measurements using resistance strain gages

NASA Technical Reports Server (NTRS)

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

1984-01-01

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

Development of intra-strain self-cloning procedure for breeding baker's yeast strains.

PubMed

Nakagawa, Youji; Ogihara, Hiroyuki; Mochizuki, Chisato; Yamamura, Hideki; Iimura, Yuzuru; Hayakawa, Masayuki

2017-03-01

Previously reported self-cloning procedures for breeding of industrial yeast strains require DNA from other strains, plasmid DNA, or mutagenesis. Therefore, we aimed to construct a self-cloning baker's yeast strain that exhibits freeze tolerance via an improved self-cloning procedure. We first disrupted the URA3 gene of a prototrophic baker's yeast strain without the use of any marker gene, resulting in a Δura3 homozygous disruptant. Then, the URA3 gene of the parental baker's yeast strain was used as a selection marker to introduce the constitutive TDH3 promoter upstream of the PDE2 gene encoding high-affinity cyclic AMP phosphodiesterase. This self-cloning procedure was performed without using DNA from other Saccharomyces cerevisiae strains, plasmid DNA, or mutagenesis and was therefore designated an intra-strain self-cloning procedure. Using this self-cloning procedure, we succeeded in producing self-cloning baker's yeast strains that harbor the TDH3p-PDE2 gene heterozygously and homozygously, designated TDH3p-PDE2 hetero and TDH3p-PDE2 homo strains, respectively. These self-cloning strains expressed much higher levels of PDE2 mRNA than the parental strain and exhibited higher viability after freeze stress, as well as higher fermentation ability in frozen dough, when compared with the parental strain. The TDH3p-PDE2 homo strain was genetically more stable than the TDH3p-PDE2 hetero strain. These results indicate that both heterozygous and homozygous strains of self-cloning PDE2-overexpressing freeze-tolerant strains of industrial baker's yeast can be prepared using the intra-strain self-cloning procedure, and, from a practical viewpoint, the TDH3p-PDE2 homo strain constructed in this study is preferable to the TDH3p-PDE2 hetero strain for frozen dough baking. Copyright © 2016 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Superlattice strain gage

DOEpatents

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

1988-06-28

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

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

NASA Technical Reports Server (NTRS)

Yamaguchi, I.

1984-01-01

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

Bioaugmentation of half-matured granular sludge with special microbial culture promoted establishment of 2,4-dichlorophenoxyacetic acid degrading aerobic granules.

PubMed

Quan, Xiangchun; Ma, Jingyun; Xiong, Weicong; Wang, Xinrui

2015-06-01

Aerobic granular sludge degrading recalcitrant compounds are generally hard to be cultivated. This study investigated the feasibility of cultivating 2,4-dichlorophenoxyacetic acid (2,4-D) degrading aerobic granules using half-matured sludge granules pre-grown on glucose as the seeds and bioaugmentation with a 2,4-D degrading strain Achromobacter sp. QXH. Results showed that bioaugmentation promoted the steady transformation of glucose-grown granules to 2,4-D degrading sludge granules and fast establishment of 2,4-D degradation ability. The 2,4-D degradation rate of the bioaugmented granules was enhanced by 36-62 % compared to the control at 2,4-D concentrations of 144-565 mg/L on Day 18. The inoculated strain was incorporated into the half-matured granules successfully and survived till the end of operation (220 days). Sludge granules at a mean size of 420 µm and capable of utilizing 500 mg/L 2,4-D as the sole carbon source were finally obtained. Sludge microbial community shifted slightly during the whole operation and the dominant bacteria species belonged to Proteobacteria.

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

PubMed Central

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

2014-01-01

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 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. PMID:22493855

Complete amino acid sequence of bovine colostrum low-Mr cysteine proteinase inhibitor.

PubMed

Hirado, M; Tsunasawa, S; Sakiyama, F; Niinobe, M; Fujii, S

1985-07-01

The complete amino acid sequence of bovine colostrum cysteine proteinase inhibitor was determined by sequencing native inhibitor and peptides obtained by cyanogen bromide degradation, Achromobacter lysylendopeptidase digestion and partial acid hydrolysis of reduced and S-carboxymethylated protein. Achromobacter peptidase digestion was successfully used to isolate two disulfide-containing peptides. The inhibitor consists of 112 amino acids with an Mr of 12787. Two disulfide bonds were established between Cys 66 and Cys 77 and between Cys 90 and Cys 110. A high degree of homology in the sequence was found between the colostrum inhibitor and human gamma-trace, human salivary acidic protein and chicken egg-white cystatin.

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

PubMed Central

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

2015-01-01

Background Although cutaneous ulcers (CU) in the tropics is frequently attributed to Treponema pallidum subspecies pertenue, the causative agent of yaws, Haemophilus ducreyi has emerged as a major cause of CU in yaws-endemic regions of the South Pacific islands and Africa. H. ducreyi is generally susceptible to macrolides, but CU strains persist after mass drug administration of azithromycin for yaws or trachoma. H. ducreyi also causes genital ulcers (GU) and was thought to be exclusively transmitted by microabrasions that occur during sex. In human volunteers, the GU strain 35000HP does not infect intact skin; wounds are required to initiate infection. These data led to several questions: Are CU strains a new variant of H. ducreyi or did they evolve from GU strains? Do CU strains contain additional genes that could allow them to infect intact skin? Are CU strains susceptible to azithromycin? Methodology/Principal Findings To address these questions, we performed whole-genome sequencing and antibiotic susceptibility testing of 5 CU strains obtained from Samoa and Vanuatu and 9 archived class I and class II GU strains. Except for single nucleotide polymorphisms, the CU strains were genetically almost identical to the class I strain 35000HP and had no additional genetic content. Phylogenetic analysis showed that class I and class II strains formed two separate clusters and CU strains evolved from class I strains. Class I strains diverged from class II strains ~1.95 million years ago (mya) and CU strains diverged from the class I strain 35000HP ~0.18 mya. CU and GU strains evolved under similar selection pressures. Like 35000HP, the CU strains were highly susceptible to antibiotics, including azithromycin. Conclusions/Significance These data suggest that CU strains are derivatives of class I strains that were not recognized until recently. These findings require confirmation by analysis of CU strains from other regions. PMID:26147869

Factors affecting finite strain estimation in low-grade, low-strain clastic rocks

NASA Astrophysics Data System (ADS)

Pastor-Galán, Daniel; Gutiérrez-Alonso, Gabriel; Meere, Patrick A.; Mulchrone, Kieran F.

2009-12-01

The computer strain analysis methods SAPE, MRL and DTNNM have permitted the characterization of finite strain in two different regions with contrasting geodynamic scenarios; (1) the Talas Ala Tau (Tien Shan, Kyrgyzs Republic) and (2) the Somiedo Nappe and Narcea Antiform (Cantabrian to West Asturian-Leonese Zone boundary, Variscan Belt, NW of Iberia). The performed analyses have revealed low-strain values and the regional strain trend in both studied areas. This study also investigates the relationship between lithology (grain size and percentage of matrix) and strain estimates the two methodologies used. The results show that these methods are comparable and the absence of significant finite strain lithological control in rocks deformed under low metamorphic and low-strain conditions.

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

NASA Technical Reports Server (NTRS)

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.

Purple corn-associated rhizobacteria with potential for plant growth promotion.

PubMed

Castellano-Hinojosa, A; Pérez-Tapia, V; Bedmar, E J; Santillana, N

2018-05-01

Purple corn (Zea mays var. purple amylaceum) is a native variety of the Peruvian Andes, cultivated at 3000 m since the pre-Inca times without N fertilization. We aimed to isolate and identify native plant growth-promoting rhizobacteria (PGPR) for future microbial-based inoculants. Eighteen strains were isolated from the rhizosphere of purple corn plants grown without N fertilization in Ayacucho (Peru). The 16S rRNA gene clustered the 18 strains into nine groups that contained species of Bacillus, Stenotrophomonas, Achromobacter, Paenibacillus, Pseudomonas and Lysinibacillus. A representative strain from each group was selected and assayed for N 2 fixation, phosphate solubilization, indole acetic and siderophore production, 1-aminocyclopropane-1-carboxylic acid deaminase activity and biocontrol abilities. Inoculation of purple corn plants with single and combined strains selected after a principal component analysis caused significant increases in root and shoot dry weight, total C and N contents of the plants. PGPRs can support growth and crop production of purple corn in the Peruvian Andes and constitute the base for microbial-based inoculants. This study enlarges our knowledge on plant-microbial interactions in high altitude mountains and provides new applications for PGPR inoculation in purple amylaceum corn, which is part of the staple diet for the native Quechua communities. © 2018 The Society for Applied Microbiology.

Geobacteraceae strains and methods

DOEpatents

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

2015-07-07

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

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

PubMed Central

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. PMID:26529510

Mineralization of a Malaysian crude oil by Pseudomonas sp. and Achromabacter sp. isolated from coastal waters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmad, J.; Ahmad, M.F.

1995-12-31

Regarded as being a potentially effective tool to combat oil pollution, bioremediation involves mineralization, i.e., the conversion of complex hydrocarbons into harmless CO{sub 2} and water by action of microorganisms. Therefore, in achieving optimum effectiveness from the application of these products on crude oil in local environments, the capability of the bacteria to mineralize hydrocarbons was evaluated. The microbial laboratory testing of mineralization on local oil degraders involved, first, isolation of bacteria found at a port located on the west coast of Peninsular Malaysia. Subsequently, these bacteria were identified by means of Biomereux`s API 20E and 20 NE systems andmore » later screened by their growth on a Malaysian crude oil. Selected strains of Pseudomonas sp. and Achromabacter sp. were then exposed individually to a similar crude oil in a mineralization unit and monitored for 16 days for release of CO{sub 2}. Pseudomonas paucimobilis was found to produce more CO{sub 2} than Achromobacter sp. When tested under similar conditions, mixed populations of these two taxa produced more CO{sub 2} than that produced by any individual strain. Effective bioremediation of local crude in Malaysian waters can therefore be achieved from biochemically developed Pseudomonas sp. strains.« less

Photothermal strain imaging

NASA Astrophysics Data System (ADS)

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.

High temperature strain measurement with a resistance strain gage

NASA Technical Reports Server (NTRS)

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

1993-01-01

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

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

NASA Astrophysics Data System (ADS)

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.

Could petroleum biodegradation be a joint achievement of aerobic and anaerobic microrganisms in deep sea reservoirs?

PubMed Central

2011-01-01

Several studies suggest that petroleum biodegradation can be achieved by either aerobic or anaerobic microorganisms, depending on oxygen input or other electron acceptors and appropriate nutrients. Evidence from in vitro experiments with samples of petroleum formation water and oils from Pampo Field indicate that petroleum biodegradation is more likely to be a joint achievement of both aerobic and anaerobic bacterial consortium, refining our previous observations of aerobic degradation. The aerobic consortium depleted, in decreasing order, hydrocarbons > hopanes > steranes > tricyclic terpanes while the anaerobic consortium depleted hydrocarbons > steranes > hopanes > tricyclic terpanes. The oxygen content of the mixed consortia was measured from time to time revealing alternating periods of microaerobicity (O2 ~0.8 mg.L-1) and of aerobicity (O2~6.0 mg.L-1). In this experiment, the petroleum biodegradation changed from time to time, alternating periods of biodegradation similar to the aerobic process and periods of biodegradation similar to the anaerobic process. The consortia showed preferences for metabolizing hydrocarbons > hopanes > steranes > tricyclic terpanes during a 90-day period, after which this trend changed and steranes were more biodegraded than hopanes. The analysis of aerobic oil degrading microbiota by the 16S rRNA gene clone library detected the presence of Bacillus, Brevibacterium, Mesorhizobium and Achromobacter, and the analysis of the anaerobic oil degrading microbiota using the same technique detected the presence of Bacillus and Acinetobacter (facultative strains). In the mixed consortia Stenotrophomonas, Brevibacterium, Bacillus, Rhizobium, Achromobacter and 5% uncultured bacteria were detected. This is certainly a new contribution to the study of reservoir biodegradation processes, combining two of the more important accepted hypotheses. PMID:22196374

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

NASA Astrophysics Data System (ADS)

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

2011-08-01

Resistance measurements during uniaxial tensile deformation of very thin (10 nm) conducting oxide films deposited on 150 nm SiN films on polyethylene naphthalate are discussed. It is first shown that certain characteristics of resistance versus strain curves are representative for the fracture behavior of the SiN film and not for that of the thin conducting oxide film. Subsequently, it is shown that the hysteresis in curves of resistance as a function of strain offers a way to directly measure the intrinsic critical strain of the SiN film without the need to determine internal strains from independent (curvature) measurements that rely on knowledge of moduli and geometry. The method should be applicable, in general, to measure intrinsic critical strain and residual strains of thin brittle films on polymers. Advantages and limitations of the method are discussed.

Geodetic Strain Analysis Tool

NASA Technical Reports Server (NTRS)

Kedar, Sharon; Baxter, Sean C.; Parker, Jay W.; Webb, Frank H.; Owen, Susan E.; Sibthorpe, Anthony J.; Dong, Danan

2011-01-01

A geodetic software analysis tool enables the user to analyze 2D crustal strain from geodetic ground motion, and create models of crustal deformation using a graphical interface. Users can use any geodetic measurements of ground motion and derive the 2D crustal strain interactively. This software also provides a forward-modeling tool that calculates a geodetic velocity and strain field for a given fault model, and lets the user compare the modeled strain field with the strain field obtained from the user s data. Users may change parameters on-the-fly and obtain a real-time recalculation of the resulting strain field. Four data products are computed: maximum shear, dilatation, shear angle, and principal components. The current view and data dependencies are processed first. The remaining data products and views are then computed in a round-robin fashion to anticipate view changes. When an analysis or display parameter is changed, the affected data products and views are invalidated and progressively re-displayed as available. This software is designed to facilitate the derivation of the strain fields from the GPS and strain meter data that sample it to facilitate the understanding of the strengths and weaknesses of the strain field derivation from continuous GPS (CGPS) and other geodetic data from a variety of tectonic settings, to converge on the "best practices" strain derivation strategy for the Solid Earth Science ESDR System (SESES) project given the CGPS station distribution in the western U.S., and to provide SESES users with a scientific and educational tool to explore the strain field on their own with user-defined parameters.

Electronic strain-level counter

NASA Technical Reports Server (NTRS)

Pitts, F. L.; Spencer, J. L. (Inventor)

1973-01-01

An electronic strain level counter for obtaining structural strain data on in-flight aircraft is described. The device counts the number of times the strain at a point on an aircraft structural member exceeds each of several preset levels. A dead band is provided at each level to prohibit the counting of small strain variations around a given preset level.

Strain measurement based battery testing

DOEpatents

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.

Elevated temperature strain gages

NASA Technical Reports Server (NTRS)

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

1985-01-01

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

Quantitative assessment of viable cells of Lactobacillus plantarum strains in single, dual and multi-strain biofilms.

PubMed

Fernández Ramírez, Mónica D; Kostopoulos, Ioannis; Smid, Eddy J; Nierop Groot, Masja N; Abee, Tjakko

2017-03-06

Biofilms of Lactobacillus plantarum are a potential source for contamination and recontamination of food products. Although biofilms have been mostly studied using single species or even single strains, it is conceivable that in a range of environmental settings including food processing areas, biofilms are composed of multiple species with each species represented by multiple strains. In this study six spoilage related L. plantarum strains FBR1-FBR6 and the model strain L. plantarum WCFS1 were characterised in single, dual and multiple strain competition models. A quantitative PCR approach was used with added propidium monoazide (PMA) enabling quantification of intact cells in the biofilm, representing the viable cell fraction that determines the food spoilage risk. Our results show that the performance of individual strains in multi-strain cultures generally correlates with their performance in pure culture, and relative strain abundance in multi-strain biofilms positively correlated with the relative strain abundance in suspended (planktonic) cultures. Performance of individual strains in dual-strain biofilms was highly influenced by the presence of the secondary strain, and in most cases no correlation between the relative contributions of viable planktonic cells and viable cells in the biofilm was noted. The total biofilm quantified by CV staining of the dual and multi-strain biofilms formed was mainly correlated to CV values of the dominant strain obtained in single strain studies. However, the combination of strain FBR5 and strain WCFS1 showed significantly higher CV values compared to the individual performances of both strains indicating that total biofilm formation was higher in this specific condition. Notably, L. plantarum FBR5 was able to outgrow all other strains and showed the highest relative abundance in dual and multi-strain biofilms. All the dual and multi-strain biofilms contained a considerable number of viable cells, representing a potential

Strain expansion-reduction approach

NASA Astrophysics Data System (ADS)

Baqersad, Javad; Bharadwaj, Kedar

2018-02-01

Validating numerical models are one of the main aspects of engineering design. However, correlating million degrees of freedom of numerical models to the few degrees of freedom of test models is challenging. Reduction/expansion approaches have been traditionally used to match these degrees of freedom. However, the conventional reduction/expansion approaches are only limited to displacement, velocity or acceleration data. While in many cases only strain data are accessible (e.g. when a structure is monitored using strain-gages), the conventional approaches are not capable of expanding strain data. To bridge this gap, the current paper outlines a reduction/expansion technique to reduce/expand strain data. In the proposed approach, strain mode shapes of a structure are extracted using the finite element method or the digital image correlation technique. The strain mode shapes are used to generate a transformation matrix that can expand the limited set of measurement data. The proposed approach can be used to correlate experimental and analytical strain data. Furthermore, the proposed technique can be used to expand real-time operating data for structural health monitoring (SHM). In order to verify the accuracy of the approach, the proposed technique was used to expand the limited set of real-time operating data in a numerical model of a cantilever beam subjected to various types of excitations. The proposed technique was also applied to expand real-time operating data measured using a few strain gages mounted to an aluminum beam. It was shown that the proposed approach can effectively expand the strain data at limited locations to accurately predict the strain at locations where no sensors were placed.

Sb-induced strain fluctuations in a strained layer superlattice of InAs/InAsSb

NASA Astrophysics Data System (ADS)

Kim, Honggyu; Meng, Yifei; Klem, John F.; Hawkins, Samuel D.; Kim, Jin K.; Zuo, Jian-Min

2018-04-01

We show that Sb substitution for As in a MBE grown InAs/InAsSb strained layer superlattice (SLS) is accompanied by significant strain fluctuations. The SLS was observed using scanning transmission electron microscopy along the [100] zone axis where the cation and anion atomic columns are separately resolved. Strain analysis based on atomic column positions reveals asymmetrical transitions in the strain profile across the SLS interfaces. The averaged strain profile is quantitatively fitted to the segregation model, which yields a distribution of Sb in agreement with the scanning tunneling microscopy result. The subtraction of the calculated strain reveals an increase in strain fluctuations with the Sb concentration, as well as isolated regions with large strain deviations extending spatially over ˜1 nm, which suggest the presence of point defects.

Hamstring strain - aftercare

MedlinePlus

Pulled hamstring muscle; Sprain - hamstring ... There are 3 levels of hamstring strains: Grade 1 -- mild muscle strain or pull Grade 2 -- partial muscle tear Grade 3 -- complete muscle tear Recovery time depends ...

Strain Gage

NASA Technical Reports Server (NTRS)

1995-01-01

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

Relationships of left ventricular strain and strain rate to wall stress and their afterload dependency.

PubMed

Murai, Daisuke; Yamada, Satoshi; Hayashi, Taichi; Okada, Kazunori; Nishino, Hisao; Nakabachi, Masahiro; Yokoyama, Shinobu; Abe, Ayumu; Ichikawa, Ayako; Ono, Kota; Kaga, Sanae; Iwano, Hiroyuki; Mikami, Taisei; Tsutsui, Hiroyuki

2017-05-01

Whether and how left ventricular (LV) strain and strain rate correlate with wall stress is not known. Furthermore, it is not determined whether strain or strain rate is less dependent on the afterload. In 41 healthy young adults, LV global peak strain and systolic peak strain rate in the longitudinal direction (LS and LSR, respectively) and circumferential direction (CS and CSR, respectively) were measured layer-specifically using speckle tracking echocardiography (STE) before and during a handgrip exercise. Among all the points before and during the exercise, all the STE parameters significantly correlated linearly with wall stress (LS: r = -0.53, p < 0.01, LSR: r = -0.28, p < 0.05, CS in the inner layer: r = -0.72, p < 0.01, CSR in the inner layer: r = -0.47, p < 0.01). Strain more strongly correlated with wall stress than strain rate (r = -0.53 for LS vs. r = -0.28 for LSR, p < 0.05; r = -0.72 for CS vs. r = -0.47 for CSR in the inner layer, p < 0.05), whereas the interobserver variability was similar between strain and strain rate (longitudinal 6.2 vs. 5.2 %, inner circumferential 4.8 vs. 4.7 %, mid-circumferential 7.9 vs. 6.9 %, outer circumferential 10.4 vs. 9.7 %), indicating that the differences in correlation coefficients reflect those in afterload dependency. It was thus concluded that LV strain and strain rate linearly and inversely correlated with wall stress in the longitudinal and circumferential directions, and strain more strongly depended on afterload than did strain rate. Myocardial shortening should be evaluated based on the relationships between these parameters and wall stress.

Sb-induced strain fluctuations in a strained layer superlattice of InAs/InAsSb

DOE PAGES

Kim, Honggyu; Meng, Yifei; Klem, John F.; ...

2018-04-28

Here, we show that Sb substitution for As in a MBE grown InAs/InAsSb strained layer superlattice (SLS) is accompanied by significant strain fluctuations. The SLS was observed using scanning transmission electron microscopy along the [100] zone axis where the cation and anion atomic columns are separately resolved. Strain analysis based on atomic column positions reveals asymmetrical transitions in the strain profile across the SLS interfaces. The averaged strain profile is quantitatively fitted to the segregation model, which yields a distribution of Sb in agreement with our scanning tunneling microscopy result. The subtraction of the calculated strain reveals an increase inmore » strain fluctuations with the Sb concentration, as well as isolated regions with large strain deviations extending spatially over ~1 nm, which suggest the presence of point defects.« less

Sb-induced strain fluctuations in a strained layer superlattice of InAs/InAsSb

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, Honggyu; Meng, Yifei; Klem, John F.

Here, we show that Sb substitution for As in a MBE grown InAs/InAsSb strained layer superlattice (SLS) is accompanied by significant strain fluctuations. The SLS was observed using scanning transmission electron microscopy along the [100] zone axis where the cation and anion atomic columns are separately resolved. Strain analysis based on atomic column positions reveals asymmetrical transitions in the strain profile across the SLS interfaces. The averaged strain profile is quantitatively fitted to the segregation model, which yields a distribution of Sb in agreement with our scanning tunneling microscopy result. The subtraction of the calculated strain reveals an increase inmore » strain fluctuations with the Sb concentration, as well as isolated regions with large strain deviations extending spatially over ~1 nm, which suggest the presence of point defects.« less

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

NASA Astrophysics Data System (ADS)

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

2014-03-01

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

Complex strain fields

NASA Astrophysics Data System (ADS)

Bradshaw, P.

Computational techniques for accounting for extra strain rates, abnormal distributions of delta-U/delta-y, fluctuating strain rates, and the effects of body forces in modeling shear flows are discussed. Consideration is given to simple shears where the extra strain rate does not affect turbulence, thin shear layers, moderately thin shear layers, and strongly distorted flows. Attention is given to formulations based on the exact transport equations for Reynolds stress as derived from the time-averaged Navier-Stokes equations. Extra strain rates arise from curvature, lateral divergence, and bulk compression, with Coriolis forces accounting for the first, intensification of the spanwise vorticity for the second, and compression or dilation of the shear layer producing the third. The curvature forces, e.g., buoyancy and Coriolis forces, are responsible for hurricanes and tornadoes.

Thin film strain transducer

NASA Technical Reports Server (NTRS)

Rand, J. L. (Inventor)

1984-01-01

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

Elevated temperature strain gages

NASA Technical Reports Server (NTRS)

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

1986-01-01

One of the goals of the HOST Program is the development of electrical resistance strain gages for static strain measurements at temperatures equal to or greater than 1273 K. Strain gage materials must have a reproducible or predictable response to temperature, time and strain. It is the objective of this research to investigate criteria for the selection of materials for such applications through electrical properties studies. The results of the investigation of two groups of materials, refractory compounds and binary alloy solid solutions are presented.

Investigation of local strain distribution and linear electro-optic effect in strained silicon waveguides.

PubMed

Chmielak, Bartos; Matheisen, Christopher; Ripperda, Christian; Bolten, Jens; Wahlbrink, Thorsten; Waldow, Michael; Kurz, Heinrich

2013-10-21

We present detailed investigations of the local strain distribution and the induced second-order optical nonlinearity within strained silicon waveguides cladded with a Si₃N₄ strain layer. Micro-Raman Spectroscopy mappings and electro-optic characterization of waveguides with varying width w(WG) show that strain gradients in the waveguide core and the effective second-order susceptibility χ(2)(yyz) increase with reduced w(WG). For 300 nm wide waveguides a mean effective χ(2)(yyz) of 190 pm/V is achieved, which is the highest value reported for silicon so far. To gain more insight into the origin of the extraordinary large optical second-order nonlinearity of strained silicon waveguides numerical simulations of edge induced strain gradients in these structures are presented and discussed.

Simultaneous hydrocarbon biodegradation and biosurfactant production by oilfield-selected bacteria.

PubMed

Mnif, S; Chamkha, M; Labat, M; Sayadi, S

2011-09-01

To study the bacterial diversity associated with hydrocarbon biodegradation potentiality and biosurfactant production of Tunisian oilfields bacteria. Eight Tunisian hydrocarbonoclastic oilfields bacteria have been isolated and selected for further characterization studies. Phylogenetic analysis revealed that three thermophilic strains belonged to the genera Geobacillus, Bacillus and Brevibacillus, and that five mesophilic strains belonged to the genera Pseudomonas, Lysinibacillus, Achromobacter and Halomonas. The bacterial strains were cultivated on crude oil as sole carbon and energy sources, in the presence of different NaCl concentrations (1, 5 and 10%, w/v), and at 37 or 55°C. The hydrocarbon biodegradation potential of each strain was quantified by GC-MS. Strain C450R, phylogenetically related to the species Pseudomonas aeruginosa, showed the maximum crude oil degradation potentiality. During the growth of strain C450R on crude oil (2%, v/v), the emulsifying activity (E24) and glycoside content increased and reached values of 77 and 1.33 g l(-1), respectively. In addition, the surface tension (ST) decreased from 68 to 35.1 mN m(-1), suggesting the production of a rhamnolipid biosurfactant. Crude biosurfactant had been partially purified and characterized. It showed interest stability against temperature and salinity increasing and important emulsifying activity against oils and hydrocarbons. The results of this study showed the presence of diverse aerobic bacteria in Tunisian oilfields including mesophilic, thermophilic and halotolerant strains with interesting aliphatic hydrocarbon degradation potentiality, mainly for the most biosurfactant produced strains. It may be suggested that the bacterial isolates are suitable candidates for practical field application for effective in situ bioremediation of hydrocarbon-contaminated sites. © 2011 The Authors. Journal of Applied Microbiology © 2011 The Society for Applied Microbiology.

Solitary waves in morphogenesis: Determination fronts as strain-cued strain transformations among automatous cells

NASA Astrophysics Data System (ADS)

Cox, Brian N.; Landis, Chad M.

2018-02-01

We present a simple theory of a strain pulse propagating as a solitary wave through a continuous two-dimensional population of cells. A critical strain is assumed to trigger a strain transformation, while, simultaneously, cells move as automata to tend to restore a preferred cell density. We consider systems in which the strain transformation is a shape change, a burst of proliferation, or the commencement of growth (which changes the shape of the population sheet), and demonstrate isomorphism among these cases. Numerical and analytical solutions describe a strain pulse whose height does not depend on how the strain disturbance was first launched, or the rate at which the strain transformation is achieved, or the rate constant in the rule for the restorative cell motion. The strain pulse is therefore very stable, surviving the imposition of strong perturbations: it would serve well as a timing signal in development. The automatous wave formulation is simple, with few model parameters. A strong case exists for the presence of a strain pulse during amelogenesis. Quantitative analysis reveals a simple relationship between the velocity of the leading edge of the pulse in amelogenesis and the known speed of migration of ameloblast cells. This result and energy arguments support the depiction of wave motion as an automatous cell response to strain, rather than as a response to an elastic energy gradient. The theory may also contribute to understanding the determination front in somitogenesis, moving fronts of convergent-extension transformation, and mitotic wavefronts in the syncytial drosophila embryo.

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

PubMed

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. Copyright © 2016 Elsevier Ltd. All rights reserved.

[Comparison of genotype characteristics between the circulating mumps virus strain in Beijing area and the vaccine strain].

PubMed

Chen, Meng; Zhang, Tie-gang; Chen, Li-juan; Wu, Jiang; Yang, Jie; Zhang, Wei

2009-11-01

To compare the genetic characteristics of mumps virus strain circulating in Beijing with vaccine strain and to preliminarily analysis the reasons of vaccine ineffectiveness. The following methods were used: Isolation and identification of the mumps virus which had been circulating in Beijing, immunization history analysis, SH gene sequence analysis and comparison genotype homology with reference strains and analysis of the key amino acid sites of HN variation. In 38 mumps cases that virus had been isolated from, another seven cases were IgM negative. In 2007 and 2008, the positive rates on virus isolation, RT-PCR and IgM-decreased significantly, while the cases with immunization history had an increase. Cases without histories of vaccination had both higher positive rates on virus isolation and IgM. Thirty-eight strains belonged to F genotype virus, but vaccine strain was A genotype. The circulating viruses showed 5.6% sequence divergence on SH gene nucleotide and 16.0% - 18.1% from vaccine strain. Conservative hydrophobic amino acids on SH protein of some Beijing strains had changed. For example, there were 6 strains, from No.8: L-->F. The circulating viruses showed 2.3% sequence divergence on HN protein amino acid sequences and 4.2% - 5.3% from vaccine strain. Amino acids sites, which deciding the ability of cross-neutralization of the Beijing strains and vaccine strains were different. At the 354 and 356 sites, all the Beijing strains were different from the vaccine strains. The N-glycosylation sites on HN of Beijing strains were also different from those on vaccine strains. Locations 464 - 466 appeared to be NCS on Beijing strain, but locations 464 - 466 were NCR on the vaccine strains. Another 18 unknown function amino acids sites of all Beijing strains were different from those on vaccine strains. In recent years, genotype F became the main genotype of circulating strains in Beijing without genotype variation, but larger difference was found between them

Flexible piezotronic strain sensor.

PubMed

Zhou, Jun; Gu, Yudong; Fei, Peng; Mai, Wenjie; Gao, Yifan; Yang, Rusen; Bao, Gang; Wang, Zhong Lin

2008-09-01

Strain sensors based on individual ZnO piezoelectric fine-wires (PFWs; nanowires, microwires) have been fabricated by a simple, reliable, and cost-effective technique. The electromechanical sensor device consists of a single electrically connected PFW that is placed on the outer surface of a flexible polystyrene (PS) substrate and bonded at its two ends. The entire device is fully packaged by a polydimethylsiloxane (PDMS) thin layer. The PFW has Schottky contacts at its two ends but with distinctly different barrier heights. The I- V characteristic is highly sensitive to strain mainly due to the change in Schottky barrier height (SBH), which scales linear with strain. The change in SBH is suggested owing to the strain induced band structure change and piezoelectric effect. The experimental data can be well-described by the thermionic emission-diffusion model. A gauge factor of as high as 1250 has been demonstrated, which is 25% higher than the best gauge factor demonstrated for carbon nanotubes. The strain sensor developed here has applications in strain and stress measurements in cell biology, biomedical sciences, MEMS devices, structure monitoring, and more.

Molecular typing of Brucella melitensis endemic strains and differentiation from the vaccine strain Rev-1.

PubMed

Noutsios, Georgios T; Papi, Rigini M; Ekateriniadou, Loukia V; Minas, Anastasios; Kyriakidis, Dimitrios A

2012-03-01

In the present study forty-four Greek endemic strains of Br. melitensis and three reference strains were genotyped by Multi locus Variable Number Tandem Repeat (ML-VNTR) analysis based on an eight-base pair tandem repeat sequence that was revealed in eight loci of Br. melitensis genome. The forty-four strains were discriminated from the vaccine strain Rev-1 by Restriction Fragment Length Polymorphism (RFLP) and Denaturant Gradient Gel Electrophoresis (DGGE). The ML-VNTR analysis revealed that endemic, reference and vaccine strains are genetically closely related, while most of the loci tested (1, 2, 4, 5 and 7) are highly polymorphic with Hunter-Gaston Genetic Diversity Index (HGDI) values in the range of 0.939 to 0.775. Analysis of ML-VNTRs loci stability through in vitro passages proved that loci 1 and 5 are non stable. Therefore, vaccine strain can be discriminated from endemic strains by allele's clusters of loci 2, 4, 6 and 7. RFLP and DGGE were also employed to analyse omp2 gene and reveled different patterns among Rev-1 and endemic strains. In RFLP, Rev-1 revealed three fragments (282, 238 and 44 bp), while endemic strains two fragments (238 and 44 bp). As for DGGE, the electrophoretic mobility of Rev-1 is different from the endemic strains due to heterologous binding of DNA chains of omp2a and omp2b gene. Overall, our data show clearly that it is feasible to genotype endemic strains of Br. melitensis and differentiate them from vaccine strain Rev-1 with ML-VNTR, RFLP and DGGE techniques. These tools can be used for conventional investigations in brucellosis outbreaks.

Quantitative Residual Strain Analyses on Strain Hardened Nickel Based Alloy

NASA Astrophysics Data System (ADS)

Yonezawa, Toshio; Maeguchi, Takaharu; Goto, Toru; Juan, Hou

Many papers have reported about the effects of strain hardening by cold rolling, grinding, welding, etc. on stress corrosion cracking susceptibility of nickel based alloys and austenitic stainless steels for LWR pipings and components. But, the residual strain value due to cold rolling, grinding, welding, etc. is not so quantitatively evaluated.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Link, T.M.; Motta, A.T.; Koss, D.A.

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} tomore » 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.« less

Strain-specific reverse transcriptase PCR assay: means to distinguish candidate vaccine from wild-type strains of respiratory syncytial virus.

PubMed Central

Zheng, H; Peret, T C; Randolph, V B; Crowley, J C; Anderson, L J

1996-01-01

Candidate live-virus vaccines for respiratory syncytial virus are being developed and are beginning to be evaluated in clinical trials. To distinguish candidate vaccine strains from wild-type strains isolated during these trials, we developed PCR assays specific to two sets of candidate vaccine strains. The two sets were a group A strain (3A), its three attenuated, temperature-sensitive variant strains, a group B strain (2B), and its four attenuated, temperature-sensitive variant strains. The PCR assays were evaluated by testing 18 group A wild-type strains, the 3A strains, 9 group B wild-type strains, and the 2B strains. PCR specific to group A wild-type strains amplified only group A wild-type strains, and 3A-specific PCR amplified only 3A strains. PCR specific to group B wild-type strains amplified all group A and group B strains but gave a 688-bp product for group B wild-type strains, a 279-bp product for 2B strains, a 547-bp product for all group A strains, and an additional 688-bp product for some group A strains, including 3A strains. These types of PCR assays can, in conjunction with other methods, be used to efficiently distinguish candidate vaccine strains from other respiratory syncytial virus strains. PMID:8789010

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

PubMed Central

Shokryazdan, Parisa; Sieo, Chin Chin; Kalavathy, Ramasamy; Liang, Juan Boo; Alitheen, Noorjahan Banu; Faseleh Jahromi, Mohammad; Ho, Yin Wan

2014-01-01

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. PMID:25105147

Novel Human Intervertebral Disc Strain Template to Quantify Regional Three-Dimensional Strains in a Population and Compare to Internal Strains Predicted by a Finite Element Model

PubMed Central

Showalter, Brent L.; DeLucca, John F.; Peloquin, John M.; Cortes, Daniel H.; Yoder, Jonathon H.; Jacobs, Nathan T.; Wright, Alexander C.; Gee, James C.; Vresilovic, Edward J.; Elliott, Dawn M.

2017-01-01

Tissue strain is an important indicator of mechanical function, but is difficult to noninvasively measure in the intervertebral disc. The objective of this study was to generate a disc strain template, a 3D average of disc strain, of a group of human L4–L5 discs loaded in axial compression. To do so, magnetic resonance images of uncompressed discs were used to create an average disc shape. Next, the strain tensors were calculated pixel-wise by using a previously developed registration algorithm. Individual disc strain tensor components were then transformed to the template space and averaged to create the disc strain template. The strain template reduced individual variability while highlighting group trends. For example, higher axial and circumferential strains were present in the lateral and posterolateral regions of the disc, which may lead to annular tears. This quantification of group-level trends in local 3D strain is a significant step forward in the study of disc biomechanics. These trends were compared to a finite element model that had been previously validated against the disc-level mechanical response. Depending on the strain component, 81–99% of the regions within the finite element model had calculated strains within one standard deviation of the template strain results. The template creation technique provides a new measurement technique useful for a wide range of studies, including more complex loading conditions, the effect of disc pathologies and degeneration, damage mechanisms, and design and evaluation of treatments. PMID:26694516

Heat strain in cold.

PubMed

Rintamäki, Hannu; Rissanen, Sirkka

2006-07-01

In spite of increased environmental cold stress, heat strain is possible also in a cold environment. The body heat balance depends on three factors: environmental thermal conditions, metabolic heat production and thermal insulation of clothing and other protective garments. As physical exercise may increase metabolic heat production from rest values by ten times or even more, the required thermal insulation of clothing may vary accordingly. However, in most outdoor work, and often in indoor cold work, too, the thermal insulation of clothing is impractical, difficult or impossible to adjust according to the changes in physical activity. This is especially true with whole body covering garments like chemical protective clothing. As a result of this imbalance, heat strain may develop. In cold all the signs of heat strain (core temperature above 38 degrees C, warm or hot thermal sensations, increased cutaneous circulation and sweating) may not be present at the same time. Heat strain in cold may be whole body heat strain or related only to torso or core temperature. Together with heat strain in torso or body core, there can be at the same time even cold strain in peripheral parts and/or superficial layers of the body. In cold environment both the preservation of insulation and facilitation of heat loss are important. Development of clothing design is still needed to allow easy adjustments of thermal insulation.

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

PubMed Central

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

2013-01-01

Distributions of normal strain, shear strain, and strain energy density (SED) were determined across the midshaft of the third metacarpal (MCIII, or cannon bone) of 3 adult thoroughbred horses as a function of speed and gait. A complete characterization of the mechanical demands of the bone made through the stride and from mild through the extremes of locomotion was possible by using three 3-element rosette strain gauges bonded at the diaphyseal midshaft of the MCIII and evaluating the strain output with beam theory and finite element analysis. Mean ± sd values of normal strain, shear strain, and SED increased with speed and peaked during a canter (−3560±380 microstrain, 1760±470 microstrain, and 119±23 kPa, respectively). While the location of these peaks was similar across animals and gaits, the resulting strain distributions across the cortex were consistently nonuniform, establishing between a 73-fold (slow trot) to a 330-fold (canter) disparity between the sites of maximum and minimum SED for each gait cycle. Using strain power density as an estimate of strain history across the bone revealed a 154-fold disparity between peak and minimum at the walk but fell to ∼32-fold at the canter. The nonuniform, minimally varying, strain environment suggests either that bone homeostasis is mediated by magnitude-independent mechanical signals or that the duration of stimuli necessary to establish and maintain tissue integrity is relatively brief, and thus the vast majority of strain information is disregarded.—Rubin, C. T., Seeherman, H., Qin, Y.-X., Gross, T. S., The mechanical consequences of load bearing in the equine third metacarpal across speed and gait: the nonuniform distributions of normal strain, shear strain, and strain energy density. PMID:23355269

Strain Pattern in Supercooled Liquids

NASA Astrophysics Data System (ADS)

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

2016-11-01

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

Mycobacterium tuberculosis strains induce strain-specific cytokine and chemokine response in pulmonary epithelial cells.

PubMed

Mvubu, Nontobeko E; Pillay, Balakrishna; McKinnon, Lyle R; Pillay, Manormoney

2018-04-01

M. tuberculosis F15/LAM4/KZN has been associated with high transmission rates of drug resistant tuberculosis in the KwaZulu-Natal province of South Africa. The current study elucidated the cytokine/chemokine responses induced by representatives of the F15/LAM4/KZN and other dominant strain families in pulmonary epithelial cells. Multiplex cytokine analyses were performed at 24, 48 and 72h post infection of the A549 pulmonary epithelial cell line with the F15/LAM4/KZN, F28, F11, Beijing, Unique and H37Rv strains at an MOI of ∼10:1. Twenty-three anti- and pro-inflammatory cytokines/chemokines were detected at all-time intervals. Significantly high concentrations of IL-6, IFN-γ, TNF-α and G-CSF at 48h, and IL-8, IFN-γ, TNF-α, G-CSF and GM-CSF at 72h, were induced by the F28 and F15/LAM4/KZN strains, respectively. Lower levels of cytokines/chemokines were induced by either the Beijing or Unique strains at all three time intervals. All strains induced up-regulation of pathogen recognition receptors (PRRs) (TLR3 and TLR5) while only the F15/LAM4/KZN, F11 and F28 strains induced significant differential expression of TLR2 compared to the Beijing, Unique and H37Rv strains. The low induction of cytokines in epithelial cells by the Beijing strain correlates with its previously reported hypervirulent properties. High concentrations of cytokines and chemokines required for early protection against M. tuberculosis infections induced by the F15/LAM4/KZN and F28 strains suggests a lower virulence of these genotypes compared to the Beijing strain. These findings demonstrate the high diversity in host cytokine/chemokine response to early infection of pulmonary epithelial cells by different strains of M. tuberculosis. Copyright © 2017 Elsevier Ltd. All rights reserved.

Strain: Fact or Fiction?

NASA Astrophysics Data System (ADS)

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

Biological assay of attenuated strain NADL-2 and virulent strain NADL-8 of porcine parvovirus.

PubMed

Mengeling, W L; Pejsak, Z; Paul, P S

1984-11-01

Attenuated strain NADL-2 and virulent strain NADL-8 of porcine parvovirus (PPV) were titrated in vivo and in vitro under similar conditions to provide a better understanding of some of the factors involved in virulence of PPV in causing maternal reproductive failure of swine. Both strains cause fetal death when they are injected directly into fetal fluids, but only strain NADL-8 does so when administered to pregnant swine. The strains were tested for their hemagglutinating activity (HA), median cell culture infective dose (CCID50), median fetal infective dose (FID50), and median fetal lethal dose (FLD50). The FID50 and FLD50 were determined by injecting virus directly into the amniotic fluid of fetuses in utero at 44 +/- 2 days of gestation and collecting the fetuses 15 +/- 1 days later. Both strains had an HA titer of 64, suggesting that there is a similar number of virions in stock preparations. However, other measurements differed markedly. The CCID50, FID50, and FLD50 were 10(5.5), 10(3.5), and 10(0.5), respectively, for strain NADL-2, and 10(4.5), 10(7.7), and 10(6.3), respectively, for strain NADL-8. Collectively, the values indicate that more than 10,000 times as much strain NADL-2 would need to reach the conceptus transplacentally to establish infection. These observations may help to explain the different consequences of oronasal exposure of pregnant swine to these strains of PPV.

Noninvasive characterization of carotid plaque strain.

PubMed

Khan, Amir A; Sikdar, Siddhartha; Hatsukami, Thomas; Cebral, Juan; Jones, Michael; Huston, John; Howard, George; Lal, Brajesh K

2017-06-01

Current risk stratification of internal carotid artery plaques based on diameter-reducing percentage stenosis may be unreliable because ischemic stroke results from plaque disruption with atheroembolization. Biomechanical forces acting on the plaque may render it vulnerable to rupture. The feasibility of ultrasound-based quantification of plaque displacement and strain induced by hemodynamic forces and their relationship to high-risk plaques have not been determined. We studied the feasibility and reliability of carotid plaque strain measurement from clinical B-mode ultrasound images and the relationship of strain to high-risk plaque morphology. We analyzed carotid ultrasound B-mode cine loops obtained in patients with asymptomatic ≥50% stenosis during routine clinical scanning. Optical flow methods were used to quantify plaque motion and shear strain during the cardiac cycle. The magnitude (maximum absolute shear strain rate [MASSR]) and variability (entropy of shear strain rate [ESSR] and variance of shear strain rate [VSSR]) of strain were combined into a composite shear strain index (SSI), which was assessed for interscan repeatability and correlated with plaque echolucency. Nineteen patients (mean age, 70 years) constituting 36 plaques underwent imaging; 37% of patients (n = 7) showed high strain (SSI ≥0.5; MASSR, 2.2; ESSR, 39.7; VSSR, 0.03) in their plaques; the remaining clustered into a low-strain group (SSI <0.5; MASSR, 0.58; ESSR, 21.2; VSSR, 0.002). The area of echolucent morphology was greater in high-strain plaques vs low-strain plaques (28% vs 17%; P = .018). Strain measurements showed low variability on Bland-Altman plots with cluster assignment agreement of 76% on repeated scanning. Two patients developed a stroke during 2 years of follow-up; both demonstrated high SSI (≥0.5) at baseline. Carotid plaque strain is reliably computed from routine B-mode imaging using clinical ultrasound machines. High plaque strain correlates with known

Strain preservation of experimental animals: vitrification of two-cell stage embryos for multiple mouse strains.

PubMed

Eto, Tomoo; Takahashi, Riichi; Kamisako, Tsutomu

2015-04-01

Strain preservation of experimental animals is crucial for experimental reproducibility. Maintaining complete animal strains, however, is costly and there is a risk for genetic mutations as well as complete loss due to disasters or illness. Therefore, the development of effective vitrification techniques for cryopreservation of multiple experimental animal strains is important. We examined whether a vitrification method using cryoprotectant solutions, P10 and PEPeS, is suitable for preservation of multiple inbred and outbred mouse strains. First, we investigated whether our vitrification method using cryoprotectant solutions was suitable for two-cell stage mouse embryos. In vitro development of embryos exposed to the cryoprotectant solutions was similar to that of fresh controls. Further, the survival rate of the vitrified embryos was extremely high (98.1%). Next, we collected and vitrified two-cell stage embryos of 14 mouse strains. The average number of embryos obtained from one female was 7.3-33.3. The survival rate of vitrified embryos ranged from 92.8% to 99.1%, with no significant differences among mouse strains. In vivo development did not differ significantly between fresh controls and vitrified embryos of each strain. For strain preservation using cryopreserved embryos, two offspring for inbred lines and one offspring for outbred lines must be produced from two-cell stage embryos collected from one female. The expected number of surviving fetuses obtained from embryos collected from one female of either the inbred or outbred strains ranged from 2.9 to 19.5. The findings of the present study indicated that this vitrification method is suitable for strain preservation of multiple mouse strains. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

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

NASA Technical Reports Server (NTRS)

Barranger, John P.

1990-01-01

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

Colony Dimorphism in Bradyrhizobium Strains

PubMed Central

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

Echocardiographic strain and strain-rate imaging: a new tool to study regional myocardial function.

PubMed

D'hooge, Jan; Bijnens, Bart; Thoen, Jan; Van de Werf, Frans; Sutherland, George R; Suetens, Paul

2002-09-01

Ultrasonic imaging is the noninvasive clinical imaging modality of choice for diagnosing heart disease. At present, two-dimensional ultrasonic grayscale images provide a relatively cheap, fast, bedside method to study the morphology of the heart. Several methods have been proposed to assess myocardial function. These have been based on either grayscale or motion (velocity) information measured in real-time. However, the quantitative assessment of regional myocardial function remains an important goal in clinical cardiology. To do this, ultrasonic strain and strain-rate imaging have been introduced. In the clinical setting, these techniques currently only allow one component of the true three-dimensional deformation to be measured. Clinical, multidimensional strain (rate) information can currently thus only be obtained by combining data acquired using different transducer positions. Nevertheless, given the appropriate postprocessing, the clinical value of these techniques has already been shown. Moreover, multidimensional strain and strain-rate estimation of the heart in vivo by means of a single ultrasound acquisition has been shown to be feasible. In this paper, the new techniques of ultrasonic strain rate and strain imaging of the heart are reviewed in terms of definitions, data acquisition, strain-rate estimation, postprocessing, and parameter extraction. Their clinical validation and relevance will be discussed using clinical examples on relevant cardiac pathology. Based on these examples, suggestions are made for future developments of these techniques.

Strain Insensitive Optical Phase Locked Loop

NASA Technical Reports Server (NTRS)

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

1996-01-01

An apparatus is provided to allow for quasi distributed sensing of strain within a test object. Strain insensitive fiber is used to deliver a light signal to a strain sensitive fiber in an optical phase locked loop sensor configuration. The use of strain insensitive delivery fiber allows for non-integrated measurements of strain without the use of expensive electronics such as those employed in ODTR techniques. The novelty of the present invention lies in the use of strain insensitive multimode fiber. The inventors had previously developed a similar sensor with strain insensitive fiber, however it was restricted to the use of single or few mode fibers. The use of an optical phase locked loop arrangement allows for the use of multimode strain insensitive fiber.

Strain improvement of chymosin-producing strains of Aspergillus niger var. awamori using parasexual recombination.

PubMed

Bodie, E A; Armstrong, G L; Dunn-Coleman, N S

1994-05-01

Parasexual recombination was used to obtain improved chymosin-producing strains and to perform genetic analysis on existing strains. Chlorate resistance was used to select for a variety of spontaneous nitrate assimilation pathway mutations in strains previously improved for chymosin production using classical strain improvement methods including mutation and screening, and selection for 2-deoxyglucose resistance (dgr). Diploids of these improved strains were generated via parasexual recombination and were isolated on selective media by complementation of nitrate assimilation mutations. A preliminary genetic analysis of diploid and haploid segregants indicated that the dgr trait, resulting in overexpression of chymosin, was recessive. Also, mutations in two different dgr genes resulted in an increased level of chymosin production. When these mutations were combined via parasexual recombination, the resulting haploid segregants produced about 15% more chymosin than either parental strain. CHEF gel electrophoresis was used to determine the chromosomal location of the integrated chymosin DNA sequences, and to verify diploidy in one case where the chromosome composition of two haploid parents differed.

Isolation and characterization of an N-methylcarbamate insecticide-degrading methylotrophic bacterium.

PubMed Central

Topp, E; Hanson, R S; Ringelberg, D B; White, D C; Wheatcroft, R

1993-01-01

A gram-negative bacterium which hydrolyzed aryl N-methylcarbamate insecticides was isolated from an agricultural soil which quickly degraded these pesticides. This organism, designated strain ER2, grew on carbofuran as a sole source of carbon and nitrogen with a doubling time of 3 h in a mineral salts medium. The aromatic nucleus of the molecule was not metabolized, and carbofuran 7-phenol accumulated as the end product of metabolism. The insecticides carbaryl, bendiocarb, and propoxur were similarly hydrolyzed, with each yielding the corresponding phenol. Strain ER2 contained two plasmids (120 and 130 kb). A probe cloned from the pDL11 plasmid of Achromobacter sp. strain WM111, which encodes the carbofuran hydrolase (mcd) gene (P. H. Tomasek and J. S. Karns, J. Bacteriol. 171:4038-4044, 1989), hybridized to the 120-kb plasmid. Restriction fragment profiles of pDL11 and strain ER2 plasmid DNAs suggested that the 120-kb plasmid of strain ER2 is very similar to pDL11. On the basis of the results of biochemical tests, 16S rRNA sequence analysis, and membrane lipid analyses, strain ER2 was found to be a phylogenetically unique type II methylotroph. The constitutive carbofuran hydrolase activity in glucose-grown cells increased sevenfold when strain ER2 was grown in the presence of 100 mg of carbofuran per liter as the sole source of carbon and nitrogen or as the sole nitrogen source in the presence of glucose. Growth on carbofuran resulted in the induction of enzymes required for methylamine-dependent respiration and the serine pathway of formaldehyde assimilation. These results indicate that the carbofuran hydrolase mcd gene is conserved on a plasmid found in organisms from different geographic areas and that the specific activity of carbofuran degradation may increase in response to carbofuran treatment. Images PMID:7504430

Segregation of genes from donor strain during the production of recombinant congenic strains.

PubMed

van Zutphen, L F; Den Bieman, M; Lankhorst, A; Demant, P

1991-07-01

Recombinant congenic strains (RCS) constitute a set of inbred strains which are designed to dissect the genetic control of multigenic traits, such as tumour susceptibility or disease resistance. Each RCS contains a small fraction of the genome of a common donor strain, while the majority of genes stem from a common background strain. We tested at two stages of the inbreeding process in 20 RCS, derived from BALB/cHeA and STS/A, to see whether alleles from the STS/A donor strain are distributed over the RCS in a ratio as would theoretically be expected. Four marker genes (Pep-3; Pgm-1; Gpi-1 and Es-3) located at 4 different chromosomes were selected and the allelic distribution was tested after 3-4 and after 12 generations of inbreeding. The data obtained do not significantly deviate from the expected pattern, thus supporting the validity of the concept of RCS.

Thin film strain transducer. [suitable for in-flight measurement of scientific balloon strain

NASA Technical Reports Server (NTRS)

Rand, J. L. (Inventor)

1985-01-01

A strain transducer system and process for making same is disclosed wherein a beryllium-copper ring having four strain gages disposed thereon is electrically connected in Wheatstone bridge fashion to output instrumentation. Tabs are bonded to a balloon or like surface with strain on the surface causing bending of the ring and providing an electrical signal through the gages proportional to the surface strain. A figure is provided which illustrates a pattern of a one-half ring segment as placed on a sheet of beryllium-copper for chem-mill etch formation, prior to bending and welding of a pair of the segments to form a ring structure.

Relationship of compressive stress-strain response of engineering materials obtained at constant engineering and true strain rates

DOE PAGES

Song, Bo; Sanborn, Brett

2018-05-07

In this paper, a Johnson–Cook model was used as an example to analyze the relationship of compressive stress-strain response of engineering materials experimentally obtained at constant engineering and true strain rates. There was a minimal deviation between the stress-strain curves obtained at the same constant engineering and true strain rates. The stress-strain curves obtained at either constant engineering or true strain rates could be converted from one to the other, which both represented the intrinsic material response. There is no need to specify the testing requirement of constant engineering or true strain rates for material property characterization, provided that eithermore » constant engineering or constant true strain rate is attained during the experiment.« less

Relationship of compressive stress-strain response of engineering materials obtained at constant engineering and true strain rates

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Bo; Sanborn, Brett

In this paper, a Johnson–Cook model was used as an example to analyze the relationship of compressive stress-strain response of engineering materials experimentally obtained at constant engineering and true strain rates. There was a minimal deviation between the stress-strain curves obtained at the same constant engineering and true strain rates. The stress-strain curves obtained at either constant engineering or true strain rates could be converted from one to the other, which both represented the intrinsic material response. There is no need to specify the testing requirement of constant engineering or true strain rates for material property characterization, provided that eithermore » constant engineering or constant true strain rate is attained during the experiment.« less

Forming limit strains for non-linear strain path of AA6014 aluminium sheet deformed at room temperature

NASA Astrophysics Data System (ADS)

Bressan, José Divo; Liewald, Mathias; Drotleff, Klaus

2017-10-01

Forming limit strain curves of conventional aluminium alloy AA6014 sheets after loading with non-linear strain paths are presented and compared with D-Bressan macroscopic model of sheet metal rupture by critical shear stress criterion. AA6014 exhibits good formability at room temperature and, thus, is mainly employed in car body external parts by manufacturing at room temperature. According to Weber et al., experimental bi-linear strain paths were carried out in specimens with 1mm thickness by pre-stretching in uniaxial and biaxial directions up to 5%, 10% and 20% strain levels before performing Nakajima testing experiments to obtain the forming limit strain curves, FLCs. In addition, FLCs of AA6014 were predicted by employing D-Bressan critical shear stress criterion for bi-linear strain path and comparisons with the experimental FLCs were analyzed and discussed. In order to obtain the material coefficients of plastic anisotropy, strain and strain rate hardening behavior and calibrate the D-Bressan model, tensile tests, two different strain rate on specimens cut at 0°, 45° and 90° to the rolling direction and also bulge test were carried out at room temperature. The correlation of experimental bi-linear strain path FLCs is reasonably good with the predicted limit strains from D-Bressan model, assuming equivalent pre-strain calculated by Hill 1979 yield criterion.

Dynamic Tensile Properties of Iron and Steels for a Wide Range of Strain Rates and Strain

NASA Astrophysics Data System (ADS)

Kojima, Nobusato; Hayashi, Hiroyuki; Yamamoto, Terumi; Mimura, Koji; Tanimura, Shinji

The tensile stress-strain curves of iron and a variety of steels, covering a wide range of strength level, over a wide strain rate range on the order of 10-3 ~ 103 s-1, were obtained systematically by using the Sensing Block Type High Speed Material Testing System (SBTS, Saginomiya). Through intensive analysis of these results, the strain rate sensitivity of the flow stress for the large strain region, including the viscous term at high strain rates, the true fracture strength and the true fracture strain were cleared for the material group of the ferrous metals. These systematical data may be useful to develop a practical constitutive model for computer codes, including a fracture criterion for simulations of the dynamic behavior in crash worthiness studies and of work-pieces subjected to dynamic plastic working for a wide strain rate range.

The Effect of Strain Rate on the Evolution of Plane Wakes Subjected to Irrotational Strains

NASA Technical Reports Server (NTRS)

Rogers, Michael M.; Merriam, Marshal (Technical Monitor)

1996-01-01

Direct numerical simulations of time-evolving turbulent plane wakes developing in the presence of irrotational plane strain applied at three different strain rates have been generated. The strain geometry is such that the flow is compressed in the streamwise direction and expanded in the cross-stream direction with the spanwise direction being unstrained. This geometry is the temporally evolving analogue of a spatially evolving wake in an adverse pressure gradient. A pseudospectral numerical method with up to 16 million modes is used to solve the equations in a reference frame moving with the irrotational strain. The initial condition for each simulation is taken from a previous turbulent self-similar plane wake direct numerical simulation at a velocity deficit Reynolds number, Re, of about 2,000. Although the evolutions of many statistics are nearly collapsed when plotted against total strain, there are some differences owing to the different strain rate histories. The impact of strain-rate on the wake spreading rate, the peak velocity deficit, the Reynolds stress profiles, and the flow structure is examined.

A tale of two mechanisms. Strain-softening versus strain-hardening in single crystals under small stressed volumes

DOE PAGES

Bei, Hongbin; Xia, Yuzhi; Barabash, Rozaliya; ...

2015-08-10

Pre-straining defect-free single crystals will introduce heterogeneous dislocation nucleation sources that reduce the measured strength from the theoretical value, while pre-straining bulk samples will lead to strain hardening. Their competition is investigated by nanoindentation pop-in tests on variously pre-strained Mo single crystals with several indenter radii (~micrometer). Pre-straining primarily shifts deformation mechanism from homogeneous dislocation nucleation to a stochastic behavior, while strain hardening plays a secondary role, as summarized in a master plot of pop-in strength versus normalized indenter radius.

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

PubMed Central

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

Mumps Hoshino and Torii vaccine strains were distinguished from circulating wild strains.

PubMed

Sawada, Akihito; Yamaji, Yoshiaki; Nakayama, Tetsuo

2013-06-01

Aseptic meningitis and acute parotitis have been observed after mumps vaccination. Mumps outbreaks have been reported in Japan because of low vaccine coverage, and molecular differentiation is required to determine whether these cases are vaccine associated. RT-nested PCR was performed in the small hydrophobic gene region, and viruses were differentiated by restriction fragment length polymorphism assay. A total of 584 nucleotides were amplified. The PCR product of the Hoshino strain was cut into two fragments (313 and 271 nucleotides) by MfeI; that of the Torii strain was digested with EcoT22I, resulting in 332- and 252-nucleotide fragments. Both strains were genotype B and had an XbaI site, resulting in two fragments: 299 and 285 nucleotides. Current circulating wild types were cut only by XbaI or MfeI. However, the MfeI site of the wild types was different from that of the Hoshino strain, resulting in 451- and 133-nucleotide fragments. Using three restriction enzymes, two mumps vaccine strains were distinguished from wild types, and this separation was applied to the identification of vaccine-related adverse events.

Bone strain magnitude is correlated with bone strain rate in tetrapods: implications for models of mechanotransduction

PubMed Central

Aiello, B. R.; Iriarte-Diaz, J.; Blob, R. W.; Butcher, M. T.; Carrano, M. T.; Espinoza, N. R.; Main, R. P.; Ross, C. F.

2015-01-01

Hypotheses suggest that structural integrity of vertebrate bones is maintained by controlling bone strain magnitude via adaptive modelling in response to mechanical stimuli. Increased tissue-level strain magnitude and rate have both been identified as potent stimuli leading to increased bone formation. Mechanotransduction models hypothesize that osteocytes sense bone deformation by detecting fluid flow-induced drag in the bone's lacunar–canalicular porosity. This model suggests that the osteocyte's intracellular response depends on fluid-flow rate, a product of bone strain rate and gradient, but does not provide a mechanism for detection of strain magnitude. Such a mechanism is necessary for bone modelling to adapt to loads, because strain magnitude is an important determinant of skeletal fracture. Using strain gauge data from the limb bones of amphibians, reptiles, birds and mammals, we identified strong correlations between strain rate and magnitude across clades employing diverse locomotor styles and degrees of rhythmicity. The breadth of our sample suggests that this pattern is likely to be a common feature of tetrapod bone loading. Moreover, finding that bone strain magnitude is encoded in strain rate at the tissue level is consistent with the hypothesis that it might be encoded in fluid-flow rate at the cellular level, facilitating bone adaptation via mechanotransduction. PMID:26063842

Revisiting borehole strain, typhoons, and slow earthquakes using quantitative estimates of precipitation-induced strain changes

NASA Astrophysics Data System (ADS)

Hsu, Ya-Ju; Chang, Yuan-Shu; Liu, Chi-Ching; Lee, Hsin-Ming; Linde, Alan T.; Sacks, Selwyn I.; Kitagawa, Genshio; Chen, Yue-Gau

2015-06-01

Taiwan experiences high deformation rates, particularly along its eastern margin where a shortening rate of about 30 mm/yr is experienced in the Longitudinal Valley and the Coastal Range. Four Sacks-Evertson borehole strainmeters have been installed in this area since 2003. Liu et al. (2009) proposed that a number of strain transient events, primarily coincident with low-barometric pressure during passages of typhoons, were due to deep-triggered slow slip. Here we extend that investigation with a quantitative analysis of the strain responses to precipitation as well as barometric pressure and the Earth tides in order to isolate tectonic source effects. Estimates of the strain responses to barometric pressure and groundwater level changes for the different stations vary over the ranges -1 to -3 nanostrain/millibar(hPa) and -0.3 to -1.0 nanostrain/hPa, respectively, consistent with theoretical values derived using Hooke's law. Liu et al. (2009) noted that during some typhoons, including at least one with very heavy rainfall, the observed strain changes were consistent with only barometric forcing. By considering a more extensive data set, we now find that the strain response to rainfall is about -5.1 nanostrain/hPa. A larger strain response to rainfall compared to that to air pressure and water level may be associated with an additional strain from fluid pressure changes that take place due to infiltration of precipitation. Using a state-space model, we remove the strain response to rainfall, in addition to those due to air pressure changes and the Earth tides, and investigate whether corrected strain changes are related to environmental disturbances or tectonic-original motions. The majority of strain changes attributed to slow earthquakes seem rather to be associated with environmental factors. However, some events show remaining strain changes after all corrections. These events include strain polarity changes during passages of typhoons (a characteristic that is

An ultrasensitive strain sensor with a wide strain range based on graphene armour scales.

PubMed

Yang, Yi-Fan; Tao, Lu-Qi; Pang, Yu; Tian, He; Ju, Zhen-Yi; Wu, Xiao-Ming; Yang, Yi; Ren, Tian-Ling

2018-06-12

An ultrasensitive strain sensor with a wide strain range based on graphene armour scales is demonstrated in this paper. The sensor shows an ultra-high gauge factor (GF, up to 1054) and a wide strain range (ε = 26%), both of which present an advantage compared to most other flexible sensors. Moreover, the sensor is developed by a simple fabrication process. Due to the excellent performance, this strain sensor can meet the demands of subtle, large and complex human motion monitoring, which indicates its tremendous application potential in health monitoring, mechanical control, real-time motion monitoring and so on.

Large Strain Behaviour of ZEK100 Magnesium Alloy at Various Strain Rates

NASA Astrophysics Data System (ADS)

Lévesque, Julie; Kurukuri, Srihari; Mishra, Raja; Worswick, Michael; Inal, Kaan

A constitutive framework based on a rate-dependent crystal plasticity theory is employed to simulate large strain deformation in hexagonal closed-packed metals that deform by slip and twinning. The model allows the twinned zones and the parent matrix to rotate independently. ZEK100 magnesium alloy sheets which significant texture weakening compared to AZ31 sheets are investigated using the model. There is considerable in-plane anisotropy and tension compression asymmetry in the flow behavior of ZEK100. Simulations of uniaxial tension in different directions at various strain rates and the accompanying texture evolution are performed and they are in very good agreement with experimental measurements. The effect of strain rate on the activation of the various slip systems and twinning show that differences in the strain rate dependence of yield stress and Rvalues in ZEK100 have their origin in the activation of different deformation mechanisms.

Material approaches to stretchable strain sensors.

PubMed

Park, Jaeyoon; You, Insang; Shin, Sangbaie; Jeong, Unyong

2015-04-27

With the recent progress made in wearable electronics, devices now require high flexibility and stretchability up to large strain levels (typically larger than 30 % strain). Wearable strain sensors or deformable strain sensors have been gaining increasing research interest because of the rapid development of electronic skins and robotics and because of their biomedical applications. Conventional brittle strain sensors made of metals and piezoresistors are not applicable for such stretchable sensors. This Review summarizes recent advances in stretchable sensors and focuses on material aspects for high stretchability and sensitivity. It begins with a brief introduction to the Wheatstone bridge circuit of conventional resistive strain sensors. Then, studies on the manipulation of materials are reviewed, including waved structural approaches for making metals and semiconductors stretchable, the use of liquid metals, and conductive filler/elastomer composites by using percolation among the fillers. For capacitive strain sensors, the constant conductivity of the electrode is a key factor in obtaining reliable sensors. Possible approaches to developing capacitive strain sensors are presented. This Review concludes with a discussion on the major challenges and perspectives related to stretchable strain sensors. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Revision of the taxonomic status of type strains of Mesorhizobium loti and reclassification of strain USDA 3471T as the type strain of Mesorhizobiumerdmanii sp. nov. and ATCC 33669T as the type strain of Mesorhizobiumjarvisii sp. nov.

PubMed

Martínez-Hidalgo, Pilar; Ramírez-Bahena, Martha Helena; Flores-Félix, José David; Rivas, Raúl; Igual, José M; Mateos, Pedro F; Martínez-Molina, Eustoquio; León-Barrios, Milagros; Peix, Álvaro; Velázquez, Encarna

2015-06-01

The species Mesorhizobim loti was isolated from nodules of Lotus corniculatus and its type strain deposited in several collections. Some of these type strains, such as those deposited in the USDA and ATCC collections before 1990, are not coincident with the original strain, NZP 2213T, deposited in the NZP culture collection. The analysis of the 16S rRNA gene showed that strains USDA 3471T and ATCC 33669T formed independent branches from that occupied by Mesorhizobium loti NZP 2213T and related to those occupied by Mesorhizobium opportunistum WSM2075T and Mesorhizobium huakuii IFO 15243T, respectively, with 99.9 % similarity in both cases. However, the analysis of concatenated recA, atpD and glnII genes with similarities lower than 96, 98 and 94 %, respectively, between strains USDA 3471T and M. opportunistum WSM2075T and between strains ATCC 33669T and M. huakuii IFO 15243T, indicated that the strains USDA 3471T and ATCC 33669T represent different species of the genus Mesorhizobium. These results were confirmed by DNA-DNA hybridization experiments and phenotypic characterization. Therefore, the two strains were reclassified as representatives of the two species Mesorhizobium erdmanii sp. nov. (type strain USDA 3471T = CECT 8631T = LMG 17826t2T) and Mesorhizobium jarvisii sp. nov. (type strain ATCC 33669T = CECT 8632T = LMG 28313T).

Impact of a Genetically Engineered Bacterium with Enhanced Alkaline Phosphatase Activity on Marine Phytoplankton Communities

PubMed Central

Sobecky, P. A.; Schell, M. A.; Moran, M. A.; Hodson, R. E.

1996-01-01

An indigenous marine Achromobacter sp. was isolated from coastal Georgia seawater and modified in the laboratory by introduction of a plasmid with a phoA hybrid gene that directed constitutive overproduction of alkaline phosphatase. The effects of this "indigenous" genetically engineered microorganism (GEM) on phosphorus cycling were determined in seawater microcosms following the addition of a model dissolved organic phosphorus compound, glycerol 3-phosphate, at a concentration of 1 or 10 (mu)M. Within 48 h, a 2- to 10-fold increase in the concentration of inorganic phosphate occurred in microcosms containing the GEM (added at an initial density equivalent to 8% of the total bacterial population) relative to controls containing only natural microbial populations, natural populations with the unmodified Achromobacter sp., or natural populations with the Achromobacter sp. containing the plasmid but not the phoA gene. Secondary effects of the GEM on the phytoplankton community were observed after several days, evident as sustained increases in phytoplankton biomass (up to 14-fold) over that in controls. Even in the absence of added glycerol 3-phosphate, a numerically stable GEM population (averaging 3 to 5% of culturable bacteria) was established within 2 to 3 weeks of introduction into seawater. Moreover, alkaline phosphatase activity in microcosms with the GEM was substantially higher than that in controls for up to 25 days, and microcosms containing the GEM maintained the potential for net phosphate accumulation above control levels for longer than 1 month. PMID:16535222

Origin of the Strain Sensitivity for an Organic Heptazole Thin-Film and Its Strain Gauge Application

NASA Astrophysics Data System (ADS)

Bae, Heesun; Jeon, Pyo Jin; Park, Ji Hoon; Lee, Kimoon

2018-04-01

The authors report on the origin of the strain sensitivity for an organic C26H16N2 (heptazole) thinfilm and its application for the detection of tensile strain. From the electrical characterization on the thin-film transistor adopting a heptazole channel, heptazole film exhibits p-channel conduction with a relatively low value of field-effect mobility (0.05 cm2/Vs), suggesting a hopping conduction behavior via hole carriers. By analyzing the strain and temperature dependences of the electrical conductivity, we reveal that the electrical conduction for a heptazole thin-film is dominated by the variable range hopping process with quite a large energy separation (224.9 meV) between the localized states under a relatively long attenuation length (10.46 Å). This indicates that a change in the inter-grain spacing that is much larger than the attenuation length is responsible for the reversible modification of electrical conductivity depending on strain for the heptazole film. By utilizing our heptazole thin-film both as a strain sensitive passive resistor and an active semiconducting channel layer, we can achieve a strain gauge device exhibiting reversible endurance for tensile strains up to 2.12%. Consequently, this study advances the understanding of the fundamental strain sensing mechanism in a heptazole thin-film toward finding a promise material with a strain gauge for applications as potential flexible devices and/or wearable electronics.

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

NASA Technical Reports Server (NTRS)

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.

Microbial Degradation of Isopropyl-N-3-Chlorophenylcarbamate and 2-Chloroethyl-N-3-Chlorophenylcarbamate

PubMed Central

Kaufman, D. D.; Kearney, P. C.

1965-01-01

Microbial degradation of isopropyl-N-3-chlorophenylcarbamate (CIPC) and 2-chloroethyl-N-3-chlorophenylcarbamate (CEPC) was observed in a soil perfusion system. Degradation in perfused soils, and by pure cultures of effective bacterial isolates, was demonstrated by the production of 3-chloroaniline and the subsequent liberation of free chloride ion. Identified isolates effective in degrading and utilizing CIPC as a sole source of carbon included Pseudomonas striata Chester, a Flavobacterium sp., an Agrobacterium sp., and an Achromobacter sp. Identified isolates, effective in degrading and utilizing CEPC as a sole source of carbon, included an Achromobacter sp. and an Arthrobacter sp. CIPC-effective isolates degraded CEPC more slowly than CIPC, whereas CEPC-effective isolates degraded CIPC more rapidly than CEPC. Both CIPC- and CEPC-effective isolates degraded isopropyl N-phenylcarbamate (IPC) more rapidly than either CIPC or CEPC. Images Fig. 3 PMID:14325285

Culture-Independent Analysis of Bacterial Fuel Contamination Provides Insight into the Level of Concordance with the Standard Industry Practice of Aerobic Cultivation ▿ †

PubMed Central

White, Judith; Gilbert, Jack; Hill, Graham; Hill, Edward; Huse, Susan M.; Weightman, Andrew J.; Mahenthiralingam, Eshwar

2011-01-01

Bacterial diversity in contaminated fuels has not been systematically investigated using cultivation-independent methods. The fuel industry relies on phenotypic cultivation-based contaminant identification, which may lack accuracy and neglect difficult-to-culture taxa. By the use of industry practice aerobic cultivation, 16S rRNA gene sequencing, and strain genotyping, a collection of 152 unique contaminant isolates from 54 fuel samples was assembled, and a dominance of Pseudomonas (21%), Burkholderia (7%), and Bacillus (7%) was demonstrated. Denaturing gradient gel electrophoresis (DGGE) of 15 samples revealed Proteobacteria and Firmicutes to be the most abundant phyla. When 16S rRNA V6 gene pyrosequencing of four selected fuel samples (indicated by “JW”) was performed, Betaproteobacteria (42.8%) and Gammaproteobacteria (30.6%) formed the largest proportion of reads; the most abundant genera were Marinobacter (15.4%; JW57), Achromobacter (41.6%; JW63), Burkholderia (80.7%; JW76), and Halomonas (66.2%; JW78), all of which were also observed by DGGE. However, the Clostridia (38.5%) and Deltaproteobacteria (11.1%) identified by pyrosequencing in sample JW57 were not observed by DGGE or aerobic culture. Genotyping revealed three instances where identical strains were found: (i) a Pseudomonas sp. strain recovered from 2 different diesel fuel tanks at a single industrial site; (ii) a Mangroveibacter sp. strain isolated from 3 biodiesel tanks at a single refinery site; and (iii) a Burkholderia vietnamiensis strain present in two unrelated automotive diesel samples. Overall, aerobic cultivation of fuel contaminants recovered isolates broadly representative of the phyla and classes present but lacked accuracy by overrepresenting members of certain groups such as Pseudomonas. PMID:21602386

Culture-independent analysis of bacterial fuel contamination provides insight into the level of concordance with the standard industry practice of aerobis cultivation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

White, J.; Gilbert, J. A.; Hill, G.

2011-07-01

Bacterial diversity in contaminated fuels has not been systematically investigated using cultivation-independent methods. The fuel industry relies on phenotypic cultivation-based contaminant identification, which may lack accuracy and neglect difficult-to-culture taxa. By the use of industry practice aerobic cultivation, 16S rRNA gene sequencing, and strain genotyping, a collection of 152 unique contaminant isolates from 54 fuel samples was assembled, and a dominance of Pseudomonas (21%), Burkholderia (7%), and Bacillus (7%) was demonstrated. Denaturing gradient gel electrophoresis (DGGE) of 15 samples revealed Proteobacteria and Firmicutes to be the most abundant phyla. When 16S rRNA V6 gene pyrosequencing of four selected fuel samplesmore » (indicated by 'JW') was performed, Betaproteobacteria (42.8%) and Gammaproteobacteria (30.6%) formed the largest proportion of reads; the most abundant genera were Marinobacter (15.4%; JW57), Achromobacter (41.6%; JW63), Burkholderia (80.7%; JW76), and Halomonas (66.2%; JW78), all of which were also observed by DGGE. However, the Clostridia (38.5%) and Deltaproteobacteria (11.1%) identified by pyrosequencing in sample JW57 were not observed by DGGE or aerobic culture. Genotyping revealed three instances where identical strains were found: (i) a Pseudomonas sp. strain recovered from 2 different diesel fuel tanks at a single industrial site; (ii) a Mangroveibacter sp. strain isolated from 3 biodiesel tanks at a single refinery site; and (iii) a Burkholderia vietnamiensis strain present in two unrelated automotive diesel samples. Overall, aerobic cultivation of fuel contaminants recovered isolates broadly representative of the phyla and classes present but lacked accuracy by overrepresenting members of certain groups such as Pseudomonas.« less

Strain-controlled nonvolatile magnetization switching

NASA Astrophysics Data System (ADS)

Geprägs, S.; Brandlmaier, A.; Brandt, M. S.; Gross, R.; Goennenwein, S. T. B.

2014-11-01

We investigate different approaches towards a nonvolatile switching of the remanent magnetization in single-crystalline ferromagnets at room temperature via elastic strain using ferromagnetic thin film/piezoelectric actuator hybrids. The piezoelectric actuator induces a voltage-controllable strain along different crystalline directions of the ferromagnetic thin film, resulting in modifications of its magnetization by converse magnetoelastic effects. We quantify the magnetization changes in the hybrids via ferromagnetic resonance spectroscopy and superconducting quantum interference device magnetometry. These measurements demonstrate a significant strain-induced change of the magnetization, limited by an inefficient strain transfer and domain formation in the particular system studied. To overcome these obstacles, we address practicable engineering concepts and use a model to demonstrate that a strain-controlled, nonvolatile magnetization switching should be possible in appropriately engineered ferromagnetic/piezoelectric actuator hybrids.

Attachment techniques for high temperature strain

NASA Astrophysics Data System (ADS)

Wnuk, Steve P., Jr.

1993-01-01

Attachment methods for making resistive strain measurements to 2500 F were studied. A survey of available strain gages and attachment techniques was made, and the results are compiled for metal and carbon composite test materials. A theoretical analysis of strain transfer into a bonded strain gage was made, and the important physical parameters of the strain transfer medium, the ceramic matrix, were identified. A pull tester to measure pull-out tests on commonly used strain gage cements indicated that all cements tested displayed adequate strength for good strain transfer. Rokide flame sprayed coatings produced significantly stronger bonds than ceramic cements. An in-depth study of the flame spray process produced simplified installation procedures which also resulted in greater reliability and durability. Application procedures incorporating improvements made during this program are appended to the report. Strain gages installed on carbon composites, Rene' 41, 316 stainless steel, and TZM using attachment techniques developed during this program were successfully tested to 2500 F. Photographs of installation techniques, test procedures, and graphs of the test data are included in this report.

Practical on-site measurement of heat strain with the use of a perceptual strain index.

PubMed

Chan, Albert P C; Yang, Y

2016-02-01

There have been increased interests in research on quantifying heat strain of construction workers and formulating corresponding guidelines for working in hot weather. The aim of this study was to validate a subjective measurement tool, the perceptual strain index (PeSI), for measuring heat strain in real-work settings. A total of sixteen construction workers were invited to participate in the field surveys. Empiric-based human monitoring was carried out with simultaneous micrometeorological (wet-bulb globe temperature, WBGT), physiological (heart rate, HR), and perceptual (perceived exertion, RPE; thermal sensation, TS) measurements throughout the test. The relative heart rate (RHR), the physiological strain index (PSIHR), and the PeSI were then calculated accordingly. The PeSI exhibited moderate correlations with WBGT and RHR (r = 0.42 and 0.40, respectively), which indicated the PeSI was sensitive to the variants of WBGT and RHR. The results of regression analysis indicated that the PeSI changed in the same general manner as the PSIHR, with a relatively large determination coefficient (R(2) = 0.67). The established perceptual strain zone illustrated that the PeSI ranging from 7 to 8 would be the exposure limit of construction workers in hot weather. The PeSI is a simple, robust, reliable, and user-friendly tool for heat strain assessment in occupational settings. The perceptual strain zone will provide practical guidelines for on-site heat strain monitoring for construction workers.

Turbulent Plane Wakes Subjected to Successive Strains

NASA Technical Reports Server (NTRS)

Rogers, Michael M.

2003-01-01

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

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

PubMed

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.

Enzyme markers in inbred rat strains: genetics of new markers and strain profiles.

PubMed

Adams, M; Baverstock, P R; Watts, C H; Gutman, G A

1984-08-01

Twenty-six inbred strains of the laboratory rat (Rattus norvegicus) were examined for electrophoretic variation at an estimated 97 genetic loci. In addition to previously documented markers, variation was observed for the enzymes aconitase, aldehyde dehydrogenase, and alkaline phosphatase. The genetic basis of these markers (Acon-1, Ahd-2, and Akp-1) was confirmed. Linkage analysis between 35 pairwise comparisons revealed that the markers Fh-1 and Pep-3 are linked. The strain profiles of the 25 inbred strains at 11 electrophoretic markers are given.

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

PubMed

Szpara, Moriah L; Tafuri, Yolanda R; Parsons, Lance; Shamim, S Rafi; Verstrepen, Kevin J; Legendre, Matthieu; Enquist, L W

2011-10-01

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 limited sequence

Tissue Doppler, strain, and strain rate echocardiography for the assessment of left and right systolic ventricular function

PubMed Central

Pellerin, D; Sharma, R; Elliott, P; Veyrat, C

2003-01-01

Tissue Doppler (TDE), strain, and strain rate echocardiography are emerging real time ultrasound techniques that provide a measure of wall motion. They offer an objective means to quantify global and regional left and right ventricular function and to improve the accuracy and reproducibility of conventional echocardiography studies. Radial and longitudinal ventricular function can be assessed by the analysis of myocardial wall velocity and displacement indices, or by the analysis of wall deformation using the rate of deformation of a myocardial segment (strain rate) and its deformation over time (strain). A quick and easy assessment of left ventricular ejection fraction is obtained by mitral annular velocity measurement during a routine study, especially in patients with poor endocardial definition or abnormal septal motion. Strain rate and strain are less affected by passive myocardial motion and tend to be uniform throughout the left ventricle in normal subjects. This paper reviews the underlying principles of TDE, strain, and strain rate echocardiography and discusses currently available quantification tools and clinical applications. PMID:14594870

Finite element simulation and comparison of a shear strain and equivalent strain during ECAP and asymmetric rolling

NASA Astrophysics Data System (ADS)

Pesin, A.; Pustovoytov, D.; Shveyova, T.; Vafin, R.

2017-12-01

The level of a shear strain and equivalent strain plays a key role in terms of the possibility of using the asymmetric rolling process as a method of severe plastic deformation. Strain mode (pure shear or simple shear) can affect very strongly on the equivalent strain and the grain refinement of the material. This paper presents the results of FEM simulations and comparison of the equivalent strain in the aluminium alloy 5083 processed by a single-pass equal channel angular pressing (simple shear), symmetric rolling (pure shear) and asymmetric rolling (simultaneous pure and simple shear). The nonlinear effect of rolls speed ratio on the deformation characteristics during asymmetric rolling was found. Extremely high equivalent strain up to e=4.2 was reached during a single-pass asymmetric rolling. The influence of the shear strain on the level of equivalent strain is discussed. Finite element analysis of the deformation characteristics, presented in this study, can be used for optimization of the asymmetric rolling process as a method of severe plastic deformation.

HIGH-RATE FORMABILITY OF HIGH-STRENGTH ALUMINUM ALLOYS: A STUDY ON OBJECTIVITY OF MEASURED STRAIN AND STRAIN RATE

DOE Office of Scientific and Technical Information (OSTI.GOV)

Upadhyay, Piyush; Rohatgi, Aashish; Stephens, Elizabeth V.

2015-02-18

Al alloy AA7075 sheets were deformed at room temperature at strain-rates exceeding 1000 /s using the electrohydraulic forming (EHF) technique. A method that combines high speed imaging and digital image correlation technique, developed at Pacific Northwest National Laboratory, is used to investigate high strain rate deformation behavior of AA7075. For strain-rate sensitive materials, the ability to accurately model their high-rate deformation behavior is dependent upon the ability to accurately quantify the strain-rate that the material is subjected to. This work investigates the objectivity of software-calculated strain and strain rate by varying different parameters within commonly used commercially available digital imagemore » correlation software. Except for very close to the time of crack opening the calculated strain and strain rates are very consistent and independent of the adjustable parameters of the software.« less

Hydrogen production from microbial strains

DOEpatents

Harwood, Caroline S; Rey, Federico E

2012-09-18

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

Bacteriocin-like inhibitory activities of seven Lactobacillus delbrueckii subsp. bulgaricus strains against antibiotic susceptible and resistant Helicobacter pylori strains.

PubMed

Boyanova, L; Gergova, G; Markovska, R; Yordanov, D; Mitov, I

2017-12-01

The aim of the study was to detect anti-Helicobacter pylori activity of seven Lactobacillus delbrueckii subsp. bulgaricus (GLB) strains by four cell-free supernatant (CFS) types. Activity of non-neutralized and non-heat-treated (CFSs1), non-neutralized and heat-treated (CFSs2), pH neutralized, catalase-treated and non-heat-treated (CFSs3), or neutralized, catalase- and heat-treated (CFSs4) CFSs against 18 H. pylori strains (11 of which with antibiotic resistance) was evaluated. All GLB strains produced bacteriocin-like inhibitory substances (BLISs), the neutralized CFSs of two GLB strains inhibited >81% of test strains and those of four GLB strains were active against >71% of antibiotic resistant strains. Two H. pylori strains were BLIS resistant. The heating did not reduce the CFS activity. Briefly, all GLB strains evaluated produced heat-stable BLISs, although GLB and H. pylori strain susceptibility patterns exhibited differences. Bacteriocin-like inhibitory substance activity can be an advantage for the probiotic choice for H. pylori infection control. In this study, anti-Helicobacter pylori activity of seven Lactobacillus delbrueckii subsp. bulgaricus (GLB) strains was evaluated by four cell-free supernatant (CFS) types. The GLB strains produced heat-stable bacteriocin-like inhibitory substances (BLISs) with a strong anti-H. pylori activity and some neutralized, catalase- and heat-treated CFSs inhibited >83% of the test strains. Bacteriocin-like inhibitory substance production of GLB strains can render them valuable probiotics in the control of H. pylori infection. © 2017 The Society for Applied Microbiology.

Strain screen and haplotype association mapping of wheel running in inbred mouse strains.

PubMed

Lightfoot, J Timothy; Leamy, Larry; Pomp, Daniel; Turner, Michael J; Fodor, Anthony A; Knab, Amy; Bowen, Robert S; Ferguson, David; Moore-Harrison, Trudy; Hamilton, Alicia

2010-09-01

Previous genetic association studies of physical activity, in both animal and human models, have been limited in number of subjects and genetically homozygous strains used as well as number of genomic markers available for analysis. Expansion of the available mouse physical activity strain screens and the recently published dense single-nucleotide polymorphism (SNP) map of the mouse genome (approximately 8.3 million SNPs) and associated statistical methods allowed us to construct a more generalizable map of the quantitative trait loci (QTL) associated with physical activity. Specifically, we measured wheel running activity in male and female mice (average age 9 wk) in 41 inbred strains and used activity data from 38 of these strains in a haplotype association mapping analysis to determine QTL associated with activity. As seen previously, there was a large range of activity patterns among the strains, with the highest and lowest strains differing significantly in daily distance run (27.4-fold), duration of activity (23.6-fold), and speed (2.9-fold). On a daily basis, female mice ran further (24%), longer (13%), and faster (11%). Twelve QTL were identified, with three (on Chr. 12, 18, and 19) in both male and female mice, five specific to males, and four specific to females. Eight of the 12 QTL, including the 3 general QTL found for both sexes, fell into intergenic areas. The results of this study further support the findings of a moderate to high heritability of physical activity and add general genomic areas applicable to a large number of mouse strains that can be further mined for candidate genes associated with regulation of physical activity. Additionally, results suggest that potential genetic mechanisms arising from traditional noncoding regions of the genome may be involved in regulation of physical activity.

Temperature and strain registration by fibre-optic strain sensor in the polymer composite materials manufacturing

NASA Astrophysics Data System (ADS)

Matveenko, V. P.; Kosheleva, N. A.; Shardakov, I. N.; Voronkov, A. A.

2018-04-01

The presence of process-induced strains induced by various manufacturing and operational factors is one of the characteristics of polymer composite materials (PCM). Conventional methods of registration and evaluation of process-induced strains can be laborious, time-consuming and demanding in terms of technical applications. The employment of embedded fibre-optic strain sensors (FOSS) offers a real prospect of measuring residual strains. This paper demonstrates the potential for using embedded FOSS for recording technological strains in a PCM plate. The PCM plate is manufactured from prepreg, using the direct compression-moulding method. In this method, the prepared reinforcing package is placed inside a mould, heated, and then exposed to compaction pressure. The examined technology can be used for positioning FOSS between the layers of the composite material. Fibre-optic sensors, interacting with the material of the examined object, make it possible to register the evolution of the strain process during all stages of polymer-composite formation. FOSS data were recorded with interrogator ASTRO X 327. The obtained data were processed using specially developed algorithms.

Sensitivity Enhancement of FBG-Based Strain Sensor.

PubMed

Li, Ruiya; Chen, Yiyang; Tan, Yuegang; Zhou, Zude; Li, Tianliang; Mao, Jian

2018-05-17

A novel fiber Bragg grating (FBG)-based strain sensor with a high-sensitivity is presented in this paper. The proposed FBG-based strain sensor enhances sensitivity by pasting the FBG on a substrate with a lever structure. This typical mechanical configuration mechanically amplifies the strain of the FBG to enhance overall sensitivity. As this mechanical configuration has a high stiffness, the proposed sensor can achieve a high resonant frequency and a wide dynamic working range. The sensing principle is presented, and the corresponding theoretical model is derived and validated. Experimental results demonstrate that the developed FBG-based strain sensor achieves an enhanced strain sensitivity of 6.2 pm/με, which is consistent with the theoretical analysis result. The strain sensitivity of the developed sensor is 5.2 times of the strain sensitivity of a bare fiber Bragg grating strain sensor. The dynamic characteristics of this sensor are investigated through the finite element method (FEM) and experimental tests. The developed sensor exhibits an excellent strain-sensitivity-enhancing property in a wide frequency range. The proposed high-sensitivity FBG-based strain sensor can be used for small-amplitude micro-strain measurement in harsh industrial environments.

Sensitivity Enhancement of FBG-Based Strain Sensor

PubMed Central

Chen, Yiyang; Tan, Yuegang; Zhou, Zude; Mao, Jian

2018-01-01

A novel fiber Bragg grating (FBG)-based strain sensor with a high-sensitivity is presented in this paper. The proposed FBG-based strain sensor enhances sensitivity by pasting the FBG on a substrate with a lever structure. This typical mechanical configuration mechanically amplifies the strain of the FBG to enhance overall sensitivity. As this mechanical configuration has a high stiffness, the proposed sensor can achieve a high resonant frequency and a wide dynamic working range. The sensing principle is presented, and the corresponding theoretical model is derived and validated. Experimental results demonstrate that the developed FBG-based strain sensor achieves an enhanced strain sensitivity of 6.2 pm/με, which is consistent with the theoretical analysis result. The strain sensitivity of the developed sensor is 5.2 times of the strain sensitivity of a bare fiber Bragg grating strain sensor. The dynamic characteristics of this sensor are investigated through the finite element method (FEM) and experimental tests. The developed sensor exhibits an excellent strain-sensitivity-enhancing property in a wide frequency range. The proposed high-sensitivity FBG-based strain sensor can be used for small-amplitude micro-strain measurement in harsh industrial environments. PMID:29772826

Haemophilus ducreyi Cutaneous Ulcer Strains Diverged from Both Class I and Class II Genital Ulcer Strains: Implications for Epidemiological Studies

PubMed Central

Gangaiah, Dharanesh

2016-01-01

Background Haemophilus ducreyi has emerged as a major cause of cutaneous ulcers (CU) in yaws-endemic regions of the tropics in the South Pacific, South East Asia and Africa. H. ducreyi was once thought only to cause the genital ulcer (GU) disease chancroid; GU strains belong to 2 distinct classes, class I and class II. Using whole-genome sequencing of 4 CU strains from Samoa, 1 from Vanuatu and 1 from Papua New Guinea, we showed that CU strains diverged from the class I strain 35000HP and that one CU strain expressed β-lactamase. Recently, the Center for Disease Control and Prevention released the genomes of 11 additional CU strains from Vanuatu and Ghana; however, the evolutionary relationship of these CU strains to previously-characterized CU and GU strains is unknown. Methodology/Principal Findings We performed phylogenetic analysis of 17 CU and 10 GU strains. Class I and class II GU strains formed two distinct clades. The class I strains formed two subclades, one containing 35000HP and HD183 and the other containing the remainder of the class I strains. Twelve of the CU strains formed a subclone under the class I 35000HP subclade, while 2 CU strains formed a subclone under the other class I subclade. Unexpectedly, 3 of the CU strains formed a subclone under the class II clade. Phylogenetic analysis of dsrA-hgbA-ncaA sequences yielded a tree similar to that of whole-genome phylogenetic tree. Conclusions/Significance CU strains diverged from multiple lineages within both class I and class II GU strains. Multilocus sequence typing of dsrA-hgbA-ncaA could be reliably used for epidemiological investigation of CU and GU strains. As class II strains grow relatively poorly and are relatively more susceptible to vancomycin than class I strains, these findings have implications for methods to recover CU strains. Comparison of contemporary CU and GU isolates would help clarify the relationship between these entities. PMID:28027326

Haemophilus ducreyi Cutaneous Ulcer Strains Diverged from Both Class I and Class II Genital Ulcer Strains: Implications for Epidemiological Studies.

PubMed

Gangaiah, Dharanesh; Spinola, Stanley M

2016-12-01

Haemophilus ducreyi has emerged as a major cause of cutaneous ulcers (CU) in yaws-endemic regions of the tropics in the South Pacific, South East Asia and Africa. H. ducreyi was once thought only to cause the genital ulcer (GU) disease chancroid; GU strains belong to 2 distinct classes, class I and class II. Using whole-genome sequencing of 4 CU strains from Samoa, 1 from Vanuatu and 1 from Papua New Guinea, we showed that CU strains diverged from the class I strain 35000HP and that one CU strain expressed β-lactamase. Recently, the Center for Disease Control and Prevention released the genomes of 11 additional CU strains from Vanuatu and Ghana; however, the evolutionary relationship of these CU strains to previously-characterized CU and GU strains is unknown. We performed phylogenetic analysis of 17 CU and 10 GU strains. Class I and class II GU strains formed two distinct clades. The class I strains formed two subclades, one containing 35000HP and HD183 and the other containing the remainder of the class I strains. Twelve of the CU strains formed a subclone under the class I 35000HP subclade, while 2 CU strains formed a subclone under the other class I subclade. Unexpectedly, 3 of the CU strains formed a subclone under the class II clade. Phylogenetic analysis of dsrA-hgbA-ncaA sequences yielded a tree similar to that of whole-genome phylogenetic tree. CU strains diverged from multiple lineages within both class I and class II GU strains. Multilocus sequence typing of dsrA-hgbA-ncaA could be reliably used for epidemiological investigation of CU and GU strains. As class II strains grow relatively poorly and are relatively more susceptible to vancomycin than class I strains, these findings have implications for methods to recover CU strains. Comparison of contemporary CU and GU isolates would help clarify the relationship between these entities.

Molecular characterization of the probiotic strain Bacillus cereus var. toyoi NCIMB 40112 and differentiation from food poisoning strains.

PubMed

Klein, Günter

2011-07-01

Bacillus cereus var. toyoi strain NCIMB 40112 (Toyocerin), a probiotic authorized in the European Union as feed additive for swine, bovines, poultry, and rabbits, was characterized by DNA fingerprinting applying pulsed-field gel electrophoresis and multilocus sequence typing and was compared with reference strains (of clinical and environmental origins). The probiotic strain was clearly characterized by pulsed-field gel electrophoresis using the restriction enzymes Apa I and Sma I resulting in unique DNA patterns. The comparison to the clinical reference strain B. cereus DSM 4312 was done with the same restriction enzymes, and again a clear differentiation of the two strains was possible by the resulting DNA patterns. The use of the restriction enzymes Apa I and Sma I is recommended for further studies. Furthermore, multilocus sequence typing analysis revealed a sequence type (ST 111) that was different from all known STs of B. cereus strains from food poisoning incidents. Thus, a strain characterization and differentiation from food poisoning strains for the probiotic strain was possible. Copyright ©, International Association for Food Protection

Retaining large and adjustable elastic strains of kilogram-scale Nb nanowires [Better Superconductor by Elastic Strain Engineering: Kilogram-scale Free-Standing Niobium Metal Composite with Large Retained Elastic Strains

DOE PAGES

Hao, Shijie; Cui, Lishan; Wang, Hua; ...

2016-02-10

Crystals held at ultrahigh elastic strains and stresses may exhibit exceptional physical and chemical properties. Individual metallic nanowires can sustain ultra-large elastic strains of 4-7%. However, retaining elastic strains of such magnitude in kilogram-scale nanowires is challenging. Here, we find that under active load, ~5.6% elastic strain can be achieved in Nb nanowires in a composite material. Moreover, large tensile (2.8%) and compressive (-2.4%) elastic strains can be retained in kilogram-scale Nb nanowires when the composite is unloaded to a free-standing condition. It is then demonstrated that the retained tensile elastic strains of Nb nanowires significantly increase their superconducting transitionmore » temperature and critical magnetic fields, corroborating ab initio calculations based on BCS theory. This free-standing nanocomposite design paradigm opens new avenues for retaining ultra-large elastic strains in great quantities of nanowires and elastic-strain-engineering at industrial scale.« less

Optical Fibers Would Sense Local Strains

NASA Technical Reports Server (NTRS)

Egalon, Claudio O.; Rogowski, Robert S.

1994-01-01

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

Simultaneous measurement of absolute strain and differential strain based on fiber Bragg grating Fabry-Perot sensor

NASA Astrophysics Data System (ADS)

Wang, Kuiru; Wang, Bo; Yan, Binbin; Sang, Xinzhu; Yuan, Jinhui; Peng, Gang-Ding

2013-10-01

We present a fiber Bragg grating Fabry-Perot (FBG-FP) sensor using the fast Fourier transform (FFT) demodulation for measuring the absolute strain and differential strain simultaneously. The amplitude and phase characteristics of Fourier transform spectrum have been studied. The relation between the amplitude of Fourier spectrum and the differential strain has been presented. We fabricate the fiber grating FP cavity sensor, and carry out the experiment on the measurement of absolute strain and differential strain. Experimental results verify the demodulation method, and show that this sensor has a good accuracy in the scope of measurement. The demodulating method can expand the number of multiplexed sensors combining with wavelength division multiplexing and time division multiplexing.

40 CFR 180.1209 - Bacillus subtilis strain QST 713 and strain QST 713 variant soil; exemption from the requirement...

Code of Federal Regulations, 2013 CFR

2013-07-01

... strain QST 713 variant soil; exemption from the requirement of a tolerance. 180.1209 Section 180.1209... strain QST 713 and strain QST 713 variant soil; exemption from the requirement of a tolerance. An... Bacillus subtilis strain QST 713 and strain QST 713 variant soil when used in or on all food commodities...

40 CFR 180.1209 - Bacillus subtilis strain QST 713 and strain QST 713 variant soil; exemption from the requirement...

Code of Federal Regulations, 2014 CFR

2014-07-01

... strain QST 713 variant soil; exemption from the requirement of a tolerance. 180.1209 Section 180.1209... strain QST 713 and strain QST 713 variant soil; exemption from the requirement of a tolerance. An... Bacillus subtilis strain QST 713 and strain QST 713 variant soil when used in or on all food commodities...

Cellulose degrading bacteria isolated from industrial samples and the gut of native insects from Northwest of Argentina.

PubMed

Manfredi, Adriana P; Perotti, Nora I; Martínez, María A

2015-12-01

The raw materials used to produce bioethanol mostly are food crops, which has led to conflicts on food security. It is, therefore, recommended the gradual replacement for second generation substrates such as lignocellulosic materials. Herein, cellulolytic bacteria were isolated from the gut content of native larvae from Lepidoptera, Coleoptera, and adults of Isoptera. Few environmental samples from the pulp and paper feedstock were also assessed. A total of 233 isolates were obtained using enrichment cultures and classic criteria. Interestingly, several halo-forming colonies were found to be bacterial consortia that presented difficulties to take apart the microbial members. Those pure isolates which hydrolyzed cellulose in larger extend (45 strains) were selected and identified by means of 16S rRNA sequence analysis. Firmicutes was the prevalent phylum (62.2%) being Bacillus spp. the most frequent genus, while Paenibacillus, Brevibacillus, Cohnella, and Staphylococcus species were less frequent. The phylum Actinobacteria (6.7%) was represented by isolates related to Agromyces spp. and Microbacterium spp. Regarding Gram-negative bacteria (31.1%), the more depicted genus was Pseudomonas spp., and members of Achromobacter spp., Enterobacter spp., and Bacteroidetes phylum were also selected. These native bacterial strains are expected to enlarge the cellulolytic toolbox for efficient biomass deconstruction. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Strain gage system evaluation program

NASA Technical Reports Server (NTRS)

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

1978-01-01

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

Decolorization of sulfonated azo dye Metanil Yellow by newly isolated bacterial strains: Bacillus sp. strain AK1 and Lysinibacillus sp. strain AK2.

PubMed

Anjaneya, O; Souche, S Yogesh; Santoshkumar, M; Karegoudar, T B

2011-06-15

Two different bacterial strains capable of decolorizing a highly water soluble azo dye Metanil Yellow were isolated from dye contaminated soil sample collected from Atul Dyeing Industry, Bellary, India. The individual bacterial strains Bacillus sp. AK1 and Lysinibacillus sp. AK2 decolorized Metanil Yellow (200 mg L(-1)) completely within 27 and 12h respectively. Various parameters like pH, temperature, NaCl and initial dye concentrations were optimized to develop an economically feasible decolorization process. The maximum concentration of Metanil Yellow (1000 mg L(-1)) was decolorized by strains AK2 and AK1 within 78 and 84 h respectively. These strains could decolorize Metanil Yellow over a broad pH range 5.5-9.0; the optimum pH was 7.2. The decolorization of Metanil Yellow was most efficient at 40°C and confirmed by UV-visible spectroscopy, TLC, HPLC and GC/MS analysis. Further, both the strains showed the involvement of azoreductase in the decolorization process. Phytotoxicity studies of catabolic products of Metanil Yellow on the seeds of chick pea and pigeon pea revealed much reduction in the toxicity of metabolites as compared to the parent dye. These results indicating the effectiveness of strains AK1 and AK2 for the treatment of textile effluents containing azo dyes. Copyright © 2011 Elsevier B.V. All rights reserved.

Probing the prodigious strain fringes from Lourdes

NASA Astrophysics Data System (ADS)

Aerden, Domingo G. A. M.; Sayab, Mohammad

2017-12-01

We investigate the kinematics of classic sigmoidal strain fringes from Lourdes (France) and review previous genetic models, strain methods and strain rates for these microstructures. Displacement controlled quartz and calcite fibers within the fringes yield an average strain of 195% with the technique of Ramsay and Huber (1983). This agrees well with strains measured from boudinaged pyrite layers and calcite veins in the same rocks, but conflicts with ca. ∼675% strain in previous analogue models for the studied strain fringes produced by progressive simple shear. We show that the detailed geometry and orientation of fiber patterns are insufficiently explained by simple shear but imply two successive, differently oriented strain fields. Although all strain fringes have the same overall asymmetry, considerable morphological variation resulted from different amounts of rotation of pyrite grains and fringes. Minor rotation led to sharply kinked fibers that record a ca. 70° rotation of the kinematic frame. Larger (up to 145°) rotations, accommodated by antithetic sliding on pyrite-fringe contacts, produced more strongly and smoothly curved fibers. Combined with published Rb-Sr ages for the studied microstructures, our new strain data indicate an average strain rate of 1.41 10-15 s-1 during ca. 37 Myr. continuous growth.

Taxonomic and Strain-Specific Identification of the Probiotic Strain Lactobacillus rhamnosus 35 within the Lactobacillus casei Group▿

PubMed Central

Coudeyras, Sophie; Marchandin, Hélène; Fajon, Céline; Forestier, Christiane

2008-01-01

Lactobacilli are lactic acid bacteria that are widespread in the environment, including the human diet and gastrointestinal tract. Some Lactobacillus strains are regarded as probiotics because they exhibit beneficial health effects on their host. In this study, the long-used probiotic strain Lactobacillus rhamnosus 35 was characterized at a molecular level and compared with seven reference strains from the Lactobacillus casei group. Analysis of rrn operon sequences confirmed that L. rhamnosus 35 indeed belongs to the L. rhamnosus species, and both temporal temperature gradient gel electrophoresis and ribotyping showed that it is closer to the probiotic strain L. rhamnosus ATCC 53103 (also known as L. rhamnosus GG) than to the species type strain. In addition, L. casei ATCC 334 gathered in a coherent cluster with L. paracasei type strains, unlike L. casei ATCC 393, which was closer to L. zeae; this is evidence of the lack of relatedness between the two L. casei strains. Further characterization of the eight strains by pulsed-field gel electrophoresis repetitive DNA element-based PCR identified distinct patterns for each strain, whereas two isolates of L. rhamnosus 35 sampled 40 years apart could not be distinguished. By subtractive hybridization using the L. rhamnosus GG genome as a driver, we were able to isolate five L. rhamnosus 35-specific sequences, including two phage-related ones. The primer pairs designed to amplify these five regions allowed us to develop rapid and highly specific PCR-based identification methods for the probiotic strain L. rhamnosus 35. PMID:18326671

High temperature static strain measurement with an electrical resistance strain gage

NASA Technical Reports Server (NTRS)

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.

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

PubMed Central

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

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

PubMed

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.

Strains and Sprains Are a Pain

MedlinePlus

... for Educators Search English Español Strains and Sprains Are a Pain KidsHealth / For Kids / Strains and Sprains ... sports. Let's find out more about them. What Are Strains and Sprains? Muscles contract and relax (almost ...

Determination of Dynamic Recrystallization Process by Equivalent Strain

NASA Astrophysics Data System (ADS)

Qin, Xiaomei; Deng, Wei

Based on Tpнoвckiй's displacement field, equivalent strain expression was derived. And according to the dynamic recrystallization (DRX) critical strain, DRX process was determined by equivalent strain. It was found that equivalent strain distribution in deformed specimen is inhomogeneous, and it increases with increasing true strain. Under a certain true strain, equivalent strains at the center, demisemi radius or on tangential plane just below the surface of the specimen are higher than the true strain. Thus, micrographs at those positions can not exactly reflect the true microstructures under the certain true strain. With increasing strain rate, the initial and finish time of DRX decrease. The frozen microstructures of 20Mn23AlV steel with the experimental condition validate the feasibility of predicting DRX process by equivalent strain.

Chitinase producing Bt strains

Treesearch

Haim B. Gunner; Matthew Zimet; Sarah Berger

1985-01-01

Screening of 402 strains of more than 18 varieties of Bacillus thuringiensis showed chitinase to be inducible in virtually every serovar tested. Though the chitinase titre varied among strains, there was a strong correlation between enhanced lethality to spruce budworm, Choristoneura fumiferana (Clemens), and an increase in...

Specific identification of Bacillus anthracis strains

NASA Astrophysics Data System (ADS)

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.

Job strain and male fertility.

PubMed

Hjollund, Niels Henrik I; Bonde, Jens Peter E; Henriksen, Tine Brink; Giwercman, Aleksander; Olsen, Jørn

2004-01-01

Job strain, defined as high job demands and low job control, has not previously been explored as a possible determinant of male fertility. We collected prospective data on job strain among men, and describe the associations with semen quality and probability of conceiving a clinical pregnancy during a menstrual cycle. Danish couples (N = 399) who were trying to become pregnant for the first time were followed for up to 6 menstrual periods. All men collected semen samples, and a blood sample was drawn from both partners. Job demand and job control were measured by a self-administered questionnaire at entry, and in each cycle the participants recorded changes in job control or job demand during the previous 30 days. In adjusted analyses, no associations were found between any semen characteristic or sexual hormones and any job strain variable. The odds for pregnancy were not associated with job strain. Psychologic job strain encountered in normal jobs in Denmark does not seem to affect male reproductive function.

Horizontal Transfer of Plasmid-Mediated Cephalosporin Resistance Genes in the Intestine of Houseflies (Musca domestica).

PubMed

Fukuda, Akira; Usui, Masaru; Okubo, Torahiko; Tamura, Yutaka

2016-06-01

Houseflies are a mechanical vector for various types of bacteria, including antimicrobial-resistant bacteria (ARB). If the intestine of houseflies is a suitable site for the transfer of antimicrobial resistance genes (ARGs), houseflies could also serve as a biological vector for ARB. To clarify whether cephalosporin resistance genes are transferred efficiently in the housefly intestine, we compared with conjugation experiments in vivo (in the intestine) and in vitro by using Escherichia coli with eight combinations of four donor and two recipient strains harboring plasmid-mediated cephalosporin resistance genes and chromosomal-encoded rifampicin resistance genes, respectively. In the in vivo conjugation experiment, houseflies ingested donor strains for 6 hr and then recipient strains for 3 hr, and 24 hr later, the houseflies were surface sterilized and analyzed. In vitro conjugation experiments were conducted using the broth-mating method. In 3/8 combinations, the in vitro transfer frequency (Transconjugants/Donor) was ≥1.3 × 10(-4); the in vivo transfer rates of cephalosporin resistance genes ranged from 2.0 × 10(-4) to 5.7 × 10(-5). Moreover, cephalosporin resistance genes were transferred to other species of enteric bacteria of houseflies such as Achromobacter sp. and Pseudomonas fluorescens. These results suggest that houseflies are not only a mechanical vector for ARB but also a biological vector for the occurrence of new ARB through the horizontal transfer of ARGs in their intestine.

The missing link: Bordetella petrii is endowed with both the metabolic versatility of environmental bacteria and virulence traits of pathogenic Bordetellae.

PubMed

Gross, Roy; Guzman, Carlos A; Sebaihia, Mohammed; dos Santos, Vítor A P Martins; Pieper, Dietmar H; Koebnik, Ralf; Lechner, Melanie; Bartels, Daniela; Buhrmester, Jens; Choudhuri, Jomuna V; Ebensen, Thomas; Gaigalat, Lars; Herrmann, Stefanie; Khachane, Amit N; Larisch, Christof; Link, Stefanie; Linke, Burkhard; Meyer, Folker; Mormann, Sascha; Nakunst, Diana; Rückert, Christian; Schneiker-Bekel, Susanne; Schulze, Kai; Vorhölter, Frank-Jörg; Yevsa, Tetyana; Engle, Jacquelyn T; Goldman, William E; Pühler, Alfred; Göbel, Ulf B; Goesmann, Alexander; Blöcker, Helmut; Kaiser, Olaf; Martinez-Arias, Rosa

2008-09-30

Bordetella petrii is the only environmental species hitherto found among the otherwise host-restricted and pathogenic members of the genus Bordetella. Phylogenetically, it connects the pathogenic Bordetellae and environmental bacteria of the genera Achromobacter and Alcaligenes, which are opportunistic pathogens. B. petrii strains have been isolated from very different environmental niches, including river sediment, polluted soil, marine sponges and a grass root. Recently, clinical isolates associated with bone degenerative disease or cystic fibrosis have also been described. In this manuscript we present the results of the analysis of the completely annotated genome sequence of the B. petrii strain DSMZ12804. B. petrii has a mosaic genome of 5,287,950 bp harboring numerous mobile genetic elements, including seven large genomic islands. Four of them are highly related to the clc element of Pseudomonas knackmussii B13, which encodes genes involved in the degradation of aromatics. Though being an environmental isolate, the sequenced B. petrii strain also encodes proteins related to virulence factors of the pathogenic Bordetellae, including the filamentous hemagglutinin, which is a major colonization factor of B. pertussis, and the master virulence regulator BvgAS. However, it lacks all known toxins of the pathogenic Bordetellae. The genomic analysis suggests that B. petrii represents an evolutionary link between free-living environmental bacteria and the host-restricted obligate pathogenic Bordetellae. Its remarkable metabolic versatility may enable B. petrii to thrive in very different ecological niches.

The missing link: Bordetella petrii is endowed with both the metabolic versatility of environmental bacteria and virulence traits of pathogenic Bordetellae

PubMed Central

Gross, Roy; Guzman, Carlos A; Sebaihia, Mohammed; Martins dos Santos, Vítor AP; Pieper, Dietmar H; Koebnik, Ralf; Lechner, Melanie; Bartels, Daniela; Buhrmester, Jens; Choudhuri, Jomuna V; Ebensen, Thomas; Gaigalat, Lars; Herrmann, Stefanie; Khachane, Amit N; Larisch, Christof; Link, Stefanie; Linke, Burkhard; Meyer, Folker; Mormann, Sascha; Nakunst, Diana; Rückert, Christian; Schneiker-Bekel, Susanne; Schulze, Kai; Vorhölter, Frank-Jörg; Yevsa, Tetyana; Engle, Jacquelyn T; Goldman, William E; Pühler, Alfred; Göbel, Ulf B; Goesmann, Alexander; Blöcker, Helmut; Kaiser, Olaf; Martinez-Arias, Rosa

2008-01-01

Background Bordetella petrii is the only environmental species hitherto found among the otherwise host-restricted and pathogenic members of the genus Bordetella. Phylogenetically, it connects the pathogenic Bordetellae and environmental bacteria of the genera Achromobacter and Alcaligenes, which are opportunistic pathogens. B. petrii strains have been isolated from very different environmental niches, including river sediment, polluted soil, marine sponges and a grass root. Recently, clinical isolates associated with bone degenerative disease or cystic fibrosis have also been described. Results In this manuscript we present the results of the analysis of the completely annotated genome sequence of the B. petrii strain DSMZ12804. B. petrii has a mosaic genome of 5,287,950 bp harboring numerous mobile genetic elements, including seven large genomic islands. Four of them are highly related to the clc element of Pseudomonas knackmussii B13, which encodes genes involved in the degradation of aromatics. Though being an environmental isolate, the sequenced B. petrii strain also encodes proteins related to virulence factors of the pathogenic Bordetellae, including the filamentous hemagglutinin, which is a major colonization factor of B. pertussis, and the master virulence regulator BvgAS. However, it lacks all known toxins of the pathogenic Bordetellae. Conclusion The genomic analysis suggests that B. petrii represents an evolutionary link between free-living environmental bacteria and the host-restricted obligate pathogenic Bordetellae. Its remarkable metabolic versatility may enable B. petrii to thrive in very different ecological niches. PMID:18826580

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

NASA Astrophysics Data System (ADS)

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

2016-08-01

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

Altering thermal transport by strained-layer epitaxy

NASA Astrophysics Data System (ADS)

Majdi, Tahereh; Pal, Souvik; Hafreager, Anders; Murad, Sohail; Sahu, Rakesh P.; Puri, Ishwar K.

2018-05-01

Since strain changes the interatomic spacing of matter and alters electron and phonon dispersion, an applied strain can modify the thermal conductivity k of a material. We show how the strain induced by heteroepitaxy is a passive mechanism to change k in a thin film. Molecular dynamics simulations of the deposition and epitaxial growth of ZnTe thin films provide insights into the role of interfacial strain in the conductivity of a deposited film. ZnTe films grow strain-free on lattice-matched ZnTe substrates, but similar thin films grown on a lattice-mismatched CdTe substrate exhibit ˜6% biaxial in-plane tensile strain and ˜7% uniaxial out-of-plane compressive strain. In the T = 700 K-1100 K temperature range, the conductivities of strained ZnTe layers decrease to ˜60% of their unstrained values. The resulting understanding of dk/dT shows that strain engineering can be used to alter the performance of a thermal rectifier and also provides a framework for enhancing thermoelectric devices.

Thin film strain transducer. [in-flight measurement of stress or strain in walls of high altitude balloons

NASA Technical Reports Server (NTRS)

Rand, J. L.

1981-01-01

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

Achromobactor denitrificans SP1 produces pharmaceutically active 25C prodigiosin upon utilizing hazardous di(2-ethylhexyl)phthalate

USDA-ARS?s Scientific Manuscript database

Achromobacter denitrificans SP1 isolated from soil sludge heavily contaminated with plastic waste produced a novel pharmaceutically-active 25C prodigiosin analog during growth in a simple mineral salt medium supplemented with hazardous di(2-ethylhexyl)phthalate (DEHP) blended PVC plastics (in situ) ...

Thick film wireless and powerless strain sensor

NASA Astrophysics Data System (ADS)

Jia, Yi; Sun, Ke

2006-03-01

The development of an innovative wireless strain sensing technology has a great potential to extend its applications in manufacturing, civil engineering and aerospace industry. This paper presents a novel wireless and powerless strain sensor with a multi-layer thick film structure. The sensor employs a planar inductor (L) and capacitive transducer (C) resonant tank sensing circuit, and a strain sensitive material of a polarized polyvinylidene fluoride (PVDF) piezoelectric thick film to realize the wireless strain sensing by strain to frequency conversion and to receive radio frequency electromagnetic energy for powering the sensor. The prototype sensor was designed and fabricated. The results of calibration on a strain constant cantilever beam show a great linearity and sensitivity about 0.0013 in a strain range of 0-0.018.

Strains and Stressors: An Analysis of Touchscreen Learning in Genetically Diverse Mouse Strains

PubMed Central

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 �

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

PubMed

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

Strains

MedlinePlus

... the first 3 days. After 3 days, either heat or ice may be helpful if you still have pain. Rest the pulled muscle for at least a day. If possible, keep the pulled muscle raised above your heart. Try not to use a strained muscle while ...

Genetic analysis of Saccharomyces cerevisiae strains isolated from palm wine in eastern Nigeria. Comparison with other African strains.

PubMed

Ezeronye, O U; Legras, J-L

2009-05-01

To study the yeast diversity of Nigerian palm wines by comparison with other African strains. Twenty-three Saccharomyces cerevisiae strains were obtained from palm wine samples collected at four locations in eastern Nigeria, and characterized using different molecular techniques: internal transcribed spacer restriction fragment length polymorphism and sequence analysis, pulsed field gel electrophoresis, inter delta typing and microsatellite multilocus analysis. These techniques revealed that palm wine yeasts represent a group of closely related strains that includes other West African isolates (CBS400, NCYC110, DVPG6044). Population analysis revealed an excess of homozygote strains and an allelic richness similar to wine suggestive of local domestication. Several other African yeast strains were not connected to this group. Ghana sorghum beer strains and other African strains (DBVPG1853 and MUCL28071) displayed strikingly high relatedness with European bread, beer or wine strains, and the genome of strain MUCL30909 contained African and wine-type alleles, indicating its hybrid origin. Nigerian palm wine yeast represents a local specific yeast flora, whereas a European origin or hybrid was suspected for several other Africa isolates. This study presents the first genetic characterization of an autochthonous African palm wine yeast population and confirms the idea that human intervention has favoured yeast migration.

Strain, strain rate, and the force frequency relationship in patients with and without heart failure.

PubMed

Mak, Susanna; Van Spall, Harriette G C; Wainstein, Rodrigo V; Sasson, Zion

2012-03-01

The aim of this study was to examine the effect of heart rate (HR) on indices of deformation in adults with and without heart failure (HF) who underwent simultaneous high-fidelity catheterization of the left ventricle to describe the force-frequency relationship. Right atrial pacing to control HR and high-fidelity recordings of left ventricular (LV) pressure were used to inscribe the force-frequency relationship. Simultaneous two-dimensional echocardiographic imaging was acquired for speckle-tracking analysis. Thirteen patients with normal LV function and 12 with systolic HF (LV ejection fraction, 31 ± 13%) were studied. Patients with HF had depressed isovolumic contractility and impaired longitudinal strain and strain rate. HR-dependent increases in LV+dP/dt(max), the force-frequency relationship, was demonstrated in both groups (normal LV function, baseline to 100 beats/min: 1,335 ± 296 to 1,564 ± 320 mm Hg/sec, P < .0001; HF, baseline to 100 beats/min: 970 ± 207 to 1,083 ± 233 mm Hg/sec, P < .01). Longitudinal strain decreased significantly (normal LV function, baseline to 100 beats/min: 18.0 ± 3.5% to 10.8 ± 6.0%, P < .001; HF: 9.4 ± 4.1% to 7.5 ± 3.4%, P < .01). The decrease in longitudinal strain was related to a decrease in LV end-diastolic dimensions. Strain rate did not change with right atrial pacing. Despite the inotropic effect of increasing HR, longitudinal strain decreases in parallel with stroke volume as load-dependent indices of ejection. Strain rate did not reflect the modest HR-related changes in contractility; on the other hand, the use of strain rate for quantitative stress imaging is also less likely to be confounded by chronotropic responses. Copyright © 2012 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.

Nanoscale strain mapping in battery nanostructures

NASA Astrophysics Data System (ADS)

Ulvestad, A.; Cho, H. M.; Harder, R.; Kim, J. W.; Dietze, S. H.; Fohtung, E.; Meng, Y. S.; Shpyrko, O. G.

2014-02-01

Coherent x-ray diffraction imaging is used to map the local three dimensional strain inhomogeneity and electron density distribution of two individual LiNi0.5Mn1.5O4-δ cathode nanoparticles in both ex-situ and in-situ environments. Our reconstructed images revealed a maximum strain of 0.4%. We observed different variations in strain inhomogeneity due to multiple competing effects. The compressive/tensile component of the strain is connected to the local lithium content and, on the surface, interpreted in terms of a local Jahn-Teller distortion of Mn3+. Finally, the measured strain distributions are discussed in terms of their impact on competing theoretical models of the lithiation process.

Biochemical Characterization of Prion Strains in Bank Voles

PubMed Central

Pirisinu, Laura; Marcon, Stefano; Di Bari, Michele Angelo; D’Agostino, Claudia; Agrimi, Umberto; Nonno, Romolo

2013-01-01

Prions exist as different strains exhibiting distinct disease phenotypes. Currently, the identification of prion strains is still based on biological strain typing in rodents. However, it has been shown that prion strains may be associated with distinct PrPSc biochemical types. Taking advantage of the availability of several prion strains adapted to a novel rodent model, the bank vole, we investigated if any prion strain was actually associated with distinctive PrPSc biochemical characteristics and if it was possible to univocally identify strains through PrPSc biochemical phenotypes. We selected six different vole-adapted strains (three human-derived and three animal-derived) and analyzed PrPSc from individual voles by epitope mapping of protease resistant core of PrPSc (PrPres) and by conformational stability and solubility assay. Overall, we discriminated five out of six prion strains, while two different scrapie strains showed identical PrPSc types. Our results suggest that the biochemical strain typing approach here proposed was highly discriminative, although by itself it did not allow us to identify all prion strains analyzed. PMID:25437201

Strain effects on oxygen migration in perovskites.

PubMed

Mayeshiba, Tam; Morgan, Dane

2015-01-28

Fast oxygen transport materials are necessary for a range of technologies, including efficient and cost-effective solid oxide fuel cells, gas separation membranes, oxygen sensors, chemical looping devices, and memristors. Strain is often proposed as a method to enhance the performance of oxygen transport materials, but the magnitude of its effect and its underlying mechanisms are not well-understood, particularly in the widely-used perovskite-structured oxygen conductors. This work reports on an ab initio prediction of strain effects on migration energetics for nine perovskite systems of the form LaBO3, where B = [Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Ga]. Biaxial strain, as might be easily produced in epitaxial systems, is predicted to lead to approximately linear changes in migration energy. We find that tensile biaxial strain reduces the oxygen vacancy migration barrier across the systems studied by an average of 66 meV per percent strain for a single selected hop, with a low of 36 and a high of 89 meV decrease in migration barrier per percent strain across all systems. The estimated range for the change in migration barrier within each system is ±25 meV per percent strain when considering all hops. These results suggest that strain can significantly impact transport in these materials, e.g., a 2% tensile strain can increase the diffusion coefficient by about three orders of magnitude at 300 K (one order of magnitude at 500 °C or 773 K) for one of the most strain-responsive materials calculated here (LaCrO3). We show that a simple elasticity model, which assumes only dilative or compressive strain in a cubic environment and a fixed migration volume, can qualitatively but not quantitatively model the strain dependence of the migration energy, suggesting that factors not captured by continuum elasticity play a significant role in the strain response.

Nanocomposite Strain Gauges Having Small TCRs

NASA Technical Reports Server (NTRS)

Gregory, Otto; Chen, Ximing

2009-01-01

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

Two-Dimensional Laser-Speckle Surface-Strain Gauge

NASA Technical Reports Server (NTRS)

Barranger, John P.; Lant, Christian

1992-01-01

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

[Phylogenetic relationship of street rabies virus strains and their antigenic reactivity with antibodies induced by vaccine strains. I. Analysis of phylogenetic relationship of street rabies virus strains isolated in Poland].

PubMed

Sadkowska-Todys, M

2000-01-01

The aims of these studies were: genetic characteristic of street rabies virus strains isolated from different animal species in Poland and determination of phylogenetic relationships to reference laboratory strains of the street rabies viruses belonging to genotype 1 and 5. The variability of rabies isolates and their phylogenetic relationship were studied by comparing the nucleotide sequence of the virus genome fragment. The Polish strains of genotype 1 belong to four phylogenetic groups (NE, CE, NEE, EE) corresponding to four variants: fox-racoon dog (F-RD); European fox 1 (F1); European fox 2 (F2) and European fox 3 (F3). On the Polish territories there are no rabies strains representing the variant dog-wolf and typical for arctic fox variant. The similarity of nucleotide and amino acid sequences of street rabies strains belonging to genotype 1 and laboratory strain CVS is very high. It is about 91% similarity at nucleotide level and 95% at amino acid level. Rabies strain CVS is similar to genotype 5 bat strains (EBL 1) only in about 69% and 74% at nucleotide and amino acid level, respectively. The genetic divergence of rabies strains circulating in Poland raised the need of permanent epidemiological and virological surveillance. The genotype and variant of isolated strains should be determined (using PCR and RLFP methods).

Ultra High Strain Rate Nanoindentation Testing.

PubMed

Sudharshan Phani, Pardhasaradhi; Oliver, Warren Carl

2017-06-17

Strain rate dependence of indentation hardness has been widely used to study time-dependent plasticity. However, the currently available techniques limit the range of strain rates that can be achieved during indentation testing. Recent advances in electronics have enabled nanomechanical measurements with very low noise levels (sub nanometer) at fast time constants (20 µs) and high data acquisition rates (100 KHz). These capabilities open the doors for a wide range of ultra-fast nanomechanical testing, for instance, indentation testing at very high strain rates. With an accurate dynamic model and an instrument with fast time constants, step load tests can be performed which enable access to indentation strain rates approaching ballistic levels (i.e., 4000 1/s). A novel indentation based testing technique involving a combination of step load and constant load and hold tests that enables measurement of strain rate dependence of hardness spanning over seven orders of magnitude in strain rate is presented. A simple analysis is used to calculate the equivalent uniaxial response from indentation data and compared to the conventional uniaxial data for commercial purity aluminum. Excellent agreement is found between the indentation and uniaxial data over several orders of magnitude of strain rate.

Use of colony-based bacterial strain typing for tracking the fate of Lactobacillus strains during human consumption

PubMed Central

2009-01-01

Background The Lactic Acid Bacteria (LAB) are important components of the healthy gut flora and have been used extensively as probiotics. Understanding the cultivable diversity of LAB before and after probiotic administration, and being able to track the fate of administered probiotic isolates during feeding are important parameters to consider in the design of clinical trials to assess probiotic efficacy. Several methods may be used to identify bacteria at the strain level, however, PCR-based methods such as Random Amplified Polymorphic DNA (RAPD) are particularly suited to rapid analysis. We examined the cultivable diversity of LAB in the human gut before and after feeding with two Lactobacillus strains, and also tracked the fate of these two administered strains using a RAPD technique. Results A RAPD typing scheme was developed to genetically type LAB isolates from a wide range of species, and optimised for direct application to bacterial colony growth. A high-throughput strategy for fingerprinting the cultivable diversity of human faeces was developed and used to determine: (i) the initial cultivable LAB strain diversity in the human gut, and (ii) the fate of two Lactobacillus strains (Lactobacillus salivarius NCIMB 30211 and Lactobacillus acidophilus NCIMB 30156) contained within a capsule that was administered in a small-scale human feeding study. The L. salivarius strain was not cultivated from the faeces of any of the 12 volunteers prior to capsule administration, but appeared post-feeding in four. Strains matching the L. acidophilus NCIMB 30156 feeding strain were found in the faeces of three volunteers prior to consumption; after taking the Lactobacillus capsule, 10 of the 12 volunteers were culture positive for this strain. The appearance of both Lactobacillus strains during capsule consumption was statistically significant (p < 0.05). Conclusion We have shown that genetic strain typing of the cultivable human gut microbiota can be evaluated using a high

Strain-induced three-photon effects

NASA Astrophysics Data System (ADS)

Jeong, Jae-Woo; Shin, Sung-Chul; Lyubchanskii, I. L.; Varyukhin, V. N.

2000-11-01

Strain-induced three-photon effects such as optical second-harmonic generation and hyper-Rayleigh light scattering, characterized by electromagnetic radiation at the double frequency of an incident light, are phenomenologically investigated by adopting a nonlinear photoelastic interaction. The relations between the strain and the nonlinear optical susceptibility for crystal surfaces with point symmetries of 4mm and 3m are described by a symmetry analysis of the nonlinear photoelastic tensor. We theoretically demonstrate a possibility of determining the strain components by measuring the rotational anisotropy of radiation at the second-harmonic frequency. Hyper-Rayleigh light scattering by dislocation strain is also described using a nonlinear photoelastic tensor. The angular dependencies of light scattered at the double frequency of an incident light for different scattering geometries are analyzed.

AN ORGANOTYPIC UNIAXIAL STRAIN MODEL USING MICROFLUIDICS

PubMed Central

Dollé, Jean-Pierre; Morrison, Barclay; Schloss, Rene R.; Yarmush, Martin L.

2012-01-01

Traumatic brain injuries are the leading cause of disability each year in the US. The most common and devastating consequence is the stretching of axons caused by shear deformation that occurs during rotational acceleration of the brain during injury. The injury effects on axonal molecular and functional events are not fully characterized. We have developed a strain injury model that maintains the three dimensional cell architecture and neuronal networks found in vivo with the ability to visualize individual axons and their response to a mechanical injury. The advantage of this model is that it can apply uniaxial strains to axons that make functional connections between two organotypic slices and injury responses can be observed in real-time and over long term. This uniaxial strain model was designed to be capable of applying an array of mechanical strains at various rates of strain, thus replicating a range of modes of axonal injury. Long term culture, preservation of slice and cell orientation, and slice-slice connection on the device was demonstrated. The device has the ability to strain either individual axons or bundles of axons through the control of microchannel dimensions. The fidelity of the model was verified by observing characteristic responses to various strain injuries which included axonal beading, delayed elastic effects and breakdown in microtubules. Microtubule breakdown was shown to be dependent on the degree of the applied strain field, where maximal breakdown was observed at peak strain and minimal breakdown is observed at low strain. This strain injury model could be a powerful tool in assessing strain injury effects on functional axonal connections. PMID:23233120

Optical fiber sensor technique for strain measurement

DOEpatents

Butler, Michael A.; Ginley, David S.

1989-01-01

Laser light from a common source is split and conveyed through two similar optical fibers and emitted at their respective ends to form an interference pattern, one of the optical fibers having a portion thereof subjected to a strain. Changes in the strain cause changes in the optical path length of the strain fiber, and generate corresponding changes in the interference pattern. The interference pattern is received and transduced into signals representative of fringe shifts corresponding to changes in the strain experienced by the strained one of the optical fibers. These signals are then processed to evaluate strain as a function of time, typical examples of the application of the apparatus including electrodeposition of a metallic film on a conductive surface provided on the outside of the optical fiber being strained, so that strains generated in the optical fiber during the course of the electrodeposition are measurable as a function of time. In one aspect of the invention, signals relating to the fringe shift are stored for subsequent processing and analysis, whereas in another aspect of the invention the signals are processed for real-time display of the strain changes under study.

Removal of benzene, toluene, xylene and styrene by biotrickling filters and identification of their interactions

PubMed Central

Li, Enze; Li, Jianjun; Zeng, Peiyuan; Feng, Rongfang; Xu, Meiying

2018-01-01

Biotrickling filters (BTFs) are becoming very potential means to purify waste gases containing multiple VOC components, but the removal of the waste gases by BTF has been a major challenge due to the extremely complicated interactions among the components. Four biotrickling filters packed with polyurethane foam were employed to identify the interactions among four aromatic compounds (benzene, toluene, xylene and styrene). The elimination capacities obtained at 90% of removal efficiency for individual toluene, styrene and xylene were 297.02, 225.27 and 180.75 g/m3h, respectively. No obvious removal for benzene was observed at the inlet loading rates ranging from 20 to 450 g/m3h. The total elimination capacities for binary gases significantly decreased in all biotrickling filters. However, the removal of benzene was enhanced in the presence of other gases. The removal capacities of ternary and quaternary gases were further largely lowered. High-throughput sequencing results revealed that microbial communities changed greatly with the composition of gases, from which we found that: all samples were dominated either by the genus Achromobacter or the Burkholderia. Different gaseous combination enriched or inhibited some microbial species. Group I includes samples of BTFs treating single and binary gases and was dominated by the genus Achromobacter, with little Burkholderia inside. Group II includes the rest of the samples taken from BTFs domesticated with ternary and quaternary gases, and was dominated by the genus Burkholderia, with little Achromobacter detected. These genera were highly associated with the biodegradation of benzene series in BTFs. PMID:29293540

Dependence of the Brillouin gain spectrum on linear strain distribution for optical time-domain reflectometer-type strain sensors

NASA Astrophysics Data System (ADS)

Naruse, Hiroshi; Tateda, Mitsuhiro; Ohno, Hiroshige; Shimada, Akiyoshi

2002-12-01

We theoretically derive the shape of the Brillouin gain spectrum, that is, the Brillouin backscattered-light power spectrum, produced in an optical fiber under conditions of a strain distribution that changes linearly with a constant slope. The modeled measurement system is an optical time-domain reflectometer-type strain sensor system. The linear strain distribution is one of the fundamental distributions and is produced in, for example, a beam to which a concentrated load is applied. By analyzing a function that expresses the shape of the derived Brillouin gain spectrum, we show that the strain calculated from the frequency at which the spectrum has a peak value coincides with that at the center of the effective pulsed light. In addition, the peak value and the full width at half-maximum of the Brillouin gain spectrum are both influenced by the strain difference between the two ends of the effective pulse. We investigate this influence in detail and obtain the relationship between strain difference and strain measurement error.

Two-dimensional strain echocardiography technology for evaluation of myocardial strain in swimming athletes after high-intensity exercise.

PubMed

Liang, Chen; Ma, Yun; Gao, Can; Zhang, Jianhong; Yang, Min; Chen, Gen; Fu, Shan; Zhu, Tiangang

2017-02-01

The aim of this study was to investigate the change in myocardial strain in swimming athletes before and after high-intensity exercise using two-dimensional strain echocardiography (2DSE) technology. To assess whether the local and overall myocardial function and myocardial injury are accurately measured using 2DSE technology, 15 swimming athletes were selected as research objects. We applied 2DSE technology to track the 2D ultrasound images of the apical four chambers, the apical two chambers, and the apical long axis before and after high-intensity, increasing-load exercise. We recorded indices such as the left ventricular global strain (GS) and the left ventricular segmental wall longitudinal peak systolic strain (PS) in 18 systoles and analyzed the myocardial strain change before and after exercise. After high-intensity exercise, the overall myocardial strain decreased, especially the strain of the posterior wall, posterior divider, lateral wall, lower wall, and the basal and middle segments of the anterior wall. The influence of exercise on myocardial strain was greater on the basal and middle segments than on the apical segment. One-time intensive exercise negatively affected the myocardial muscle. Myocardial muscles in the apical segment and the myocardial wall were more sensitive to intensive exercise. The 2DSE technology can precisely position the motion-sensitive areas and help locate myocardial injury. © 2017, Wiley Periodicals, Inc.

Strain engineering of van der Waals heterostructures.

PubMed

Vermeulen, Paul A; Mulder, Jefta; Momand, Jamo; Kooi, Bart J

2018-01-18

Modifying the strain state of solids allows control over a plethora of functional properties. The weak interlayer bonding in van der Waals (vdWaals) materials such as graphene, hBN, MoS 2 , and Bi 2 Te 3 might seem to exclude strain engineering, since strain would immediately relax at the vdWaals interfaces. Here we present direct observations of the contrary by showing growth of vdWaals heterostructures with persistent in-plane strains up to 5% and we show that strain relaxation follows a not yet reported process distinctly different from strain relaxation in three-dimensionally bonded (3D) materials. For this, 2D bonded Bi 2 Te 3 -Sb 2 Te 3 and 2D/3D bonded Bi 2 Te 3 -GeTe multilayered films are grown using Pulsed Laser Deposition (PLD) and their structure is monitored in situ using Reflective High Energy Electron Diffraction (RHEED) and post situ analysis is performed using Transmission Electron Microscopy (TEM). Strain relaxation is modeled and found to solely depend on the layer being grown and its initial strain. This insight demonstrates that strain engineering of 2D bonded heterostructures obeys different rules than hold for epitaxial 3D materials and opens the door to precise tuning of the strain state of the individual layers to optimize functional performance of vdWaals heterostructures.

StrainSeeker: fast identification of bacterial strains from raw sequencing reads using user-provided guide trees.

PubMed

Roosaare, Märt; Vaher, Mihkel; Kaplinski, Lauris; Möls, Märt; Andreson, Reidar; Lepamets, Maarja; Kõressaar, Triinu; Naaber, Paul; Kõljalg, Siiri; Remm, Maido

2017-01-01

Fast, accurate and high-throughput identification of bacterial isolates is in great demand. The present work was conducted to investigate the possibility of identifying isolates from unassembled next-generation sequencing reads using custom-made guide trees. A tool named StrainSeeker was developed that constructs a list of specific k -mers for each node of any given Newick-format tree and enables the identification of bacterial isolates in 1-2 min. It uses a novel algorithm, which analyses the observed and expected fractions of node-specific k -mers to test the presence of each node in the sample. This allows StrainSeeker to determine where the isolate branches off the guide tree and assign it to a clade whereas other tools assign each read to a reference genome. Using a dataset of 100 Escherichia coli isolates, we demonstrate that StrainSeeker can predict the clades of E. coli with 92% accuracy and correct tree branch assignment with 98% accuracy. Twenty-five thousand Illumina HiSeq reads are sufficient for identification of the strain. StrainSeeker is a software program that identifies bacterial isolates by assigning them to nodes or leaves of a custom-made guide tree. StrainSeeker's web interface and pre-computed guide trees are available at http://bioinfo.ut.ee/strainseeker. Source code is stored at GitHub: https://github.com/bioinfo-ut/StrainSeeker.

Differentiation of Mycoplasma gallisepticum vaccine strains ts-11 and 6/85 from commonly used Mycoplasma gallisepticum challenge strains by PCR.

PubMed

Evans, J D; Leigh, S A

2008-09-01

Mycoplasma gallisepticum (MG) is an important avian pathogen causing significant economic losses within the poultry industry. In an effort to develop tools to aid in MG research and diagnostics, we have compared sequences of the attenuated MG vaccine strain ts-11 to those of commonly used pathogenic challenge strains in search of a simple means of differentiation. Via gapA sequence alignments and comparisons, we have identified and designed primers facilitating strain differentiation. When applied to conventional polymerase chain reaction (PCR) assay at low annealing temperature, the primer sets allow for the differentiation of MG attenuated vaccine strains ts-11 as well as the attenuated MG vaccine strain 6/85 from the commonly utilized MG challenge strains R(low), R, and S6. Conventional PCR differentiation is based on the visualization of sole products with the attenuated MG strains ts-11 and 6/85 and the lack of the corresponding products from MG strains R(low), R, and S6. When applied to MG strain F, product visualization varies with the applied primer set. The differentiation of MG strains ts-11 and 6/85 from the pathogenic challenge strains was also accomplished via real-time analyses, however, the primer sets were not able to differentiate MG strains ts-11 and 6/85 from selected MG field isolates.

Strain distributions and their influence on electronic structures of WSe2-MoS2 laterally strained heterojunctions

NASA Astrophysics Data System (ADS)

Zhang, Chendong; Li, Ming-Yang; Tersoff, Jerry; Han, Yimo; Su, Yushan; Li, Lain-Jong; Muller, David A.; Shih, Chih-Kang

2018-02-01

Monolayer transition metal dichalcogenide heterojunctions, including vertical and lateral p-n junctions, have attracted considerable attention due to their potential applications in electronics and optoelectronics. Lattice-misfit strain in atomically abrupt lateral heterojunctions, such as WSe2-MoS2, offers a new band-engineering strategy for tailoring their electronic properties. However, this approach requires an understanding of the strain distribution and its effect on band alignment. Here, we study a WSe2-MoS2 lateral heterojunction using scanning tunnelling microscopy and image its moiré pattern to map the full two-dimensional strain tensor with high spatial resolution. Using scanning tunnelling spectroscopy, we measure both the strain and the band alignment of the WSe2-MoS2 lateral heterojunction. We find that the misfit strain induces type II to type I band alignment transformation. Scanning transmission electron microscopy reveals the dislocations at the interface that partially relieve the strain. Finally, we observe a distinctive electronic structure at the interface due to hetero-bonding.

Effect of Static Strains on Diffusion

NASA Technical Reports Server (NTRS)

Girifalco, L. A.; Grimes, H. H.

1961-01-01

A theory is developed that gives the diffusion coefficient in strained systems as an exponential function of the strain. This theory starts with the statistical theory of the atomic jump frequency as developed by Vineyard. The parameter determining the effect of strain on diffusion is related to the changes in the inter-atomic forces with strain. Comparison of the theory with published experimental results for the effect of pressure on diffusion shows that the experiments agree with the form of the theoretical equation in all cases within experimental error.

Early Assessment of Right Ventricular Function in Systemic Lupus Erythematosus Patients using Strain and Strain Rate Imaging.

PubMed

Luo, Runlan; Cui, Hongyan; Huang, Dongmei; Sun, Lihua; Song, Shengda; Sun, Mengyao; Li, Guangsen

2018-06-11

Right ventricular function is a crucial factor of the prognosis of systemic lupus erythematosus (SLE). To evaluate the right ventricular function in SLE patients with different degrees of pulmonary hypertension (PH) by strain and strain rate imaging. A total of 102 SLE patients and 30 healthy volunteers were studied between October 2015 and May 2016. Patients were divided into three groups according to pulmonary artery systolic pressure (PASP) estimated by echocardiography: group control (A); PASP ≤ 30 mmHg (group B, n = 37); PASP 30-50 mmHg (mild PH; group C, n = 34); and PASP ≥ 50 mmHg (moderate-to-severe PH; group D, n = 31). Longitudinal peak systolic strain (ε) and strain rate (SR), including systolic strain rate (SRs), early diastolic strain rate (SRe) and late diastolic strain rate (SRa) were measured in the basal, middle and apical segments of the right ventricular free wall in participants by two-dimensional speckle tracking echocardiography (2D-STE) from the apical four-chamber view. A p < 0.05 was set for statistical significance. The parameters of ε, SRs, SRe, and SRa were significantly decreased in groups C and D compared with groups A and B. The ε of each segments was significantly lower in group D than in group C, while there were no differences in SRs, SRe and SRa between groups C and D. Strain and strain rate imaging could early detect the right ventricular dysfunction in SLE patients with PH, and provide important value for clinical therapy and prognosis of these patients. (Arq Bras Cardiol. 2018; [online].ahead print, PP.0-0).

Effects of C and Si on strain aging of strain-based API X60 pipeline steels

NASA Astrophysics Data System (ADS)

Sung, Hyo Kyung; Lee, Dong Ho; Lee, Sunghak; Lee, Byeong-Joo; Hong, Seung-Pyo; Kim, Young-Woon; Yoo, Jang Yong; Hwang, Byoungchul; Shin, Sang Yong

2017-05-01

Four types of strain-based API X60 pipeline steels were fabricated by varying the C and Si contents, and the effects of C and Si on strain aging were investigated. The 0.05 wt% C steels consisted mainly of polygonal ferrite (PF), whereas the 0.08 wt% C steels consisted of acicular ferrite (AF). The volume fraction of AF increased with increasing C content because C is an austenite stabilizer element. The volume fractions of bainitic ferrite (BF) of the 0.15 wt% Si steels were higher than those of the 0.25 wt% Si steels, whereas the volume fractions of the secondary phases were lower. From the tensile properties before and after the aging process of the strainbased API X60 pipeline steels, the yield strength increased and the uniform and total elongation decreased, which is the strain aging effect. The strain aging effect in the strain-based API X60 pipeline steels was minimized when the volume fraction of AF was increased and secondary phases were distributed uniformly. On the other hand, an excessively high C content formed fine precipitates, and the strain aging effect occurred because of the interactions among dislocations and fine precipitates.

Interplay between strain, quantum confinement, and ferromagnetism in strained ferromagnetic semiconductor (In,Fe)As thin films

NASA Astrophysics Data System (ADS)

Sasaki, Daisuke; Anh, Le Duc; Nam Hai, Pham; Tanaka, Masaaki

2014-04-01

We systematically investigated the influence of strain on the electronic structure and ferromagnetism of (In,Fe)As thin films. It is found that while the shift of the critical point energies of compressive-strained (In,Fe)As layers grown on (In1-y,Gay)As (y = 0.05, 0.1) buffer layers can be explained by the hydrostatic deformation effect (HDE) alone, those of tensile-strained (In,Fe)As layers grown on (Ga1-z,Alz)Sb (z = 0, 0.5, 1) buffer layers can be explained by the combination of HDE and the quantum confinement effect (QCE). The Curie temperature TC of the (In,Fe)As layers strongly depends on the strain, and shows a maximum for the (In,Fe)As layer grown on a GaSb buffer layer. The strain dependence of TC can be explained by the s-d exchange mechanism taking into account HDE and QCE.

5-Fluorouracil-resistant strain of Methanobacterium thermoautotrophicum.

PubMed

Nagle, D P; Teal, R; Eisenbraun, A

1987-09-01

Growth of Methanobacterium thermoautotrophicum Marburg is inhibited by the pyrimidine, 5-fluorouracil (FU). It was shown previously that methanogenesis is not inhibited to the same extent as growth. A spontaneously occurring FU-resistant strain (RTAE-1) was isolated from a culture of strain Marburg. The growth of both strains was inhibited by 5-fluorodeoxyuridine but not 5-fluorocytosine, and the wild type was more susceptible to inhibition by 5-azauracil and 6-azauracil than was strain RTAE-1. The cellular targets for the pyrimidine analogs are not known. When the accumulation of 14C-labeled uracil or FU by the two strains was compared, the wild type took up 15-fold more radiolabel per cell than did the FU-resistant strain. In the wild type, radiolabel from uracil was incorporated into the soluble pool, RNA, and DNA. The metabolism of uracil appeared to involve a uracil phosphoribosyltransferase activity. Strain Marburg extracts contained this enzyme, whereas FU-resistant strain RTAE-1 extracts had less than 1/10 as much activity. Although it is possible that a change in permeability to the compounds plays a role in the stable resistance of strain RTAE-1, the fact that it lacks the ability to metabolize pyrimidines to nucleotides is sufficient to account for its phenotype.

5-Fluorouracil-resistant strain of Methanobacterium thermoautotrophicum.

PubMed Central

Nagle, D P; Teal, R; Eisenbraun, A

1987-01-01

Growth of Methanobacterium thermoautotrophicum Marburg is inhibited by the pyrimidine, 5-fluorouracil (FU). It was shown previously that methanogenesis is not inhibited to the same extent as growth. A spontaneously occurring FU-resistant strain (RTAE-1) was isolated from a culture of strain Marburg. The growth of both strains was inhibited by 5-fluorodeoxyuridine but not 5-fluorocytosine, and the wild type was more susceptible to inhibition by 5-azauracil and 6-azauracil than was strain RTAE-1. The cellular targets for the pyrimidine analogs are not known. When the accumulation of 14C-labeled uracil or FU by the two strains was compared, the wild type took up 15-fold more radiolabel per cell than did the FU-resistant strain. In the wild type, radiolabel from uracil was incorporated into the soluble pool, RNA, and DNA. The metabolism of uracil appeared to involve a uracil phosphoribosyltransferase activity. Strain Marburg extracts contained this enzyme, whereas FU-resistant strain RTAE-1 extracts had less than 1/10 as much activity. Although it is possible that a change in permeability to the compounds plays a role in the stable resistance of strain RTAE-1, the fact that it lacks the ability to metabolize pyrimidines to nucleotides is sufficient to account for its phenotype. PMID:3624203

Complete Genomic Sequences of H3N8 Equine Influenza Virus Strains Used as Vaccine Strains in Japan

PubMed Central

Yamanaka, Takashi; Bannai, Hiroshi; Tsujimura, Koji; Kokado, Hiroshi

2018-01-01

ABSTRACT We sequenced the eight segments of influenza A virus strains A/equine/Ibaraki/1/2007 and A/equine/Yokohama/aq13/2010, which are strains of the Florida sublineage clades 1 and 2 of the H3N8 subtype equine influenza virus. These strains have been used as vaccine strains in Japan since 2016 in accordance with World Organization for Animal Health (OIE) recommendations. PMID:29567739

Complete Genomic Sequences of H3N8 Equine Influenza Virus Strains Used as Vaccine Strains in Japan.

PubMed

Nemoto, Manabu; Yamanaka, Takashi; Bannai, Hiroshi; Tsujimura, Koji; Kokado, Hiroshi

2018-03-22

We sequenced the eight segments of influenza A virus strains A/equine/Ibaraki/1/2007 and A/equine/Yokohama/aq13/2010, which are strains of the Florida sublineage clades 1 and 2 of the H3N8 subtype equine influenza virus. These strains have been used as vaccine strains in Japan since 2016 in accordance with World Organization for Animal Health (OIE) recommendations. Copyright © 2018 Nemoto et al.

Improved Hardware for Higher Spatial Resolution Strain-ENCoded (SENC) Breast MRI for Strain Measurements

PubMed Central

Harouni, Ahmed A.; Hossain, Jakir; Jacobs, Michael A.; Osman, Nael F.

2012-01-01

Introduction Early detection of breast lesions using mammography has resulted in lower mortality-rates. However, some breast lesions are mammography occult and magnetic resonance imaging (MRI) is recommended, but has lower specificity. It is possible to achieve higher specificity by using Strain-ENCoded (SENC) MRI and/or magnetic resonance elastography(MRE). SENC breast MRI can measure the strain properties of breast tissue. Similarly, MRE is used to measure elasticity (i.e., shear stiffness) of different tissue compositions interrogating the tissue mechanical properties. Reports have shown that malignant tumors are 3–13 times stiffer than normal tissue and benign tumors. Methods We have developed a Strain-ENCoded (SENC) breast hardware device capable of periodically compressing the breast, thus allowing for longer scanning time and measuring the strain characteristics of breast tissue. This hardware enabled us to use SENC MRI with high spatial resolution (1×1×5mm3) instead of Fast SENC(FSENC). Simple controls and multiple safety measures were added to ensure accurate, repeatable and safe in-vivo experiments. Results Phantom experiments showed that SENC breast MRI has higher SNR and CNR than FSENC under different scanning resolutions. Finally, the SENC breast device reproducibility measurements resulted in a difference of less than one mm with a 1% strain difference. Conclusion SENC breast MR images have higher SNR and CNR than FSENC images. Thus, combining SENC breast strain measurements with diagnostic breast MRI to differentiate benign from malignant lesions could potentially increase the specificity of diagnosis in the clinical setting. PMID:21440464

Finite Strain Behavior of Polyurea for a Wide Range of Strain Rates

DTIC Science & Technology

2010-02-01

dimensional dynamic compressive behavior of EPDM rubber ," Journal of Engineering Materials and Technology, Transaction of the ASME, 125:294-301. [97] Song, B...and Chen, W. (2004) "Dynamic compressive behavior of EPDM rubber un- der nearly uniaxial strain conditions," Journal of Engineering Materials and... rubber elastic springs to describe the steep initial stiffness of virgin butadiene rubber under tensile and compressive loading at intermediate strain

Ignition Delay Associated with a Strained Strip

NASA Technical Reports Server (NTRS)

Gerk, T. J.; Karagozian, A. R.

1996-01-01

Ignition processes associated with two adjacent fuel-oxidizer interferences bounding a strained fuel strip are explored here using single-step activation energy asymptotics. Calculations are made for constant as well as temporally decaying strain fields. There possible models of ignition are determined: one in which the two interfaces ignite independently as diffusion flames; one in which the two interfaces ignite dependently and in which ignition occurs to form a single , premixed flame at very high strain rates before ignition is completely prevented. In contrast to a single, isolated interface in which ignition can be prevented by overmatching heat production with heat convection due to strain, ignition of a strained fuel strip can also be prevented if the finite extend of fuel is diluted by oxidizer more quickly than heat production can cause a positive feedback thermal runaway. These behaviors are dependent on the relative sizes of timescales associated with species and heat diffusion, with convection due to strain, and with the chemical reaction. The result here indicate that adjacent, strained species interfaces may ignite quite differently in nature from ignition of a single, strained intrface and that their interdependence should be considered as the interfaces are brought closer together in complex strain fields. Critical strain rates leading to complete ignition delay are found to be considerably smaller for the fuel strip than those for single interfaces as the fuel strip is made thin in comparison to diffusion and chemical length scales.

Modal strain energies in COSMIC NASTRAN

NASA Technical Reports Server (NTRS)

Snyder, B. D.; Venkayya, V. B.

1989-01-01

A computer program was developed to take a NASTRAN output file from a normal modes analysis and calculate the modal strain energies of selected elements. The FORTRAN program can determine the modal strain energies for CROD, CBAR, CELAS, CTRMEM, CQDMEM2, and CSHEAR elements. Modal strain energies are useful in estimating damping in structures.

Development of strain-specific PCR primers for quantitative detection of Bacillus mesentericus strain TO-A in human feces.

PubMed

Sato, Naoki; Seo, Genichiro; Benno, Yoshimi

2014-01-01

Strain-specific polymerase chain reaction (PCR) primers for detection of Bacillus mesentericus strain TO-A (BM TO-A) were developed. The randomly amplified polymorphic DNA (RAPD) technique was used to produce potential strain-specific markers. A 991-bp RAPD marker found to be strain-specific was sequenced, and two primer pairs specific to BM TO-A were constructed based on this sequence. In addition, we explored a more specific DNA region using inverse PCR, and designed a strain-specific primer set for use in real-time quantitative PCR (qPCR). These primer pairs were tested against 25 Bacillus subtilis strains and were found to be strain-specific. After examination of the detection limit and linearity of detection of BM TO-A in feces, the qPCR method and strain-specific primers were used to quantify BM TO-A in the feces of healthy volunteers who had ingested 3×10(8) colony forming unit (CFU) of BM TO-A per day in tablets. During the administration period, BM TO-A was detected in the feces of all 24 subjects, and the average number of BM TO-A detected using the culture method and qPCR was about 10(4.8) and 10(5.8) cells per gram of feces, respectively. Using the qPCR method, BM TO-A was detected in the feces of half of the subjects 3 d after withdrawal, and was detected in the feces of only one subject 1 week after withdrawal. These results suggest that the qPCR method using BM TO-A strain-specific primers is useful for the quantitative detection of this strain in feces.

[Variations on hemagglutinin gene of Zhejiang measles virus strains and differences with measles strains circulated both at home and abroad].

PubMed

Feng, Yan; Zhong, Shu-ling; Xu, Chang-ping; Lu, Yi-yu

2013-07-01

To investigate the variations on hemagglutinin (H) gene of measles virus (MV) in Zhejiang province, and to analyze the differences with strains circulated both at home and abroad. In total, 33 MV strains isolated in Zhejiang province between 1999 and 2011 were collected.RNA of the isolated MV strains was extracted and the complete sequences on H gene were amplified using RT-PCR assay. The products were compared with the Chinese vaccine strain Shanghai-191, which was downloaded from GenBank, and other 95 different MV strains from all over the world. 33 MV strains, isolated from the throat swab specimens collected from MV patients in Zhejiang province during 1999 to 2001, were used to conduct phylogenetic analysis with MV strains circulated in other areas of China during 1993 to 2007. The phylogenetic tree based on H gene sequences showed that all the Zhejiang MV strains located in H1a cluster, and no apparent time series and geographic restrictions were observed. Compared to the referenced vaccine strain Shanghai-191, the average variation rate on nucleotides and amino acids, and the evolutionary rate of H1a viruses from China during 2003 to 2011 were separately 5.15%, 4.44% and 5.81%, which were higher than the rates of H1a viruses during 1965 to 1993 (4.75%, 3.86% and 5.30%), and the rates of viruses during 1994 to 2002 (4.80%, 4.08% and 5.37%).However, the dn/ds ratios of strains within the three time periods were 0.19,0.21 and 0.23 respectively, which indicated that no evidence of positive selection was found on H1a MV strains during 1993 to 2011. A 24 stable amino acid variation sites on H gene was found between H1a viruses during 2003 to 2011 and the vaccine strain Shanghai-191. The largest variation occurred between vaccine and H1a strains, with 0.053 of the p-distance and 26-28 of amino acid mutations.However, only 15 stable amino acid variations were found between vaccine strain and genotype B3 or D4 strains.In addition, significant differences were found

Low TCR nanocomposite strain gages

NASA Technical Reports Server (NTRS)

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

2012-01-01

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

Towards development of nanofibrous large strain flexible strain sensors with programmable shape memory properties

NASA Astrophysics Data System (ADS)

Khalili, N.; Asif, H.; Naguib, H. E.

2018-05-01

Electrospun polymeric fibers can be used as strain sensors due to their large surface to weight/volume ratio, high porosity and pore interconnectivity. Large strain flexible strain sensors are used in numerous applications including rehabilitation, health monitoring, and sports performance monitoring where large strain detection should be accommodated by the sensor. This has boosted the demand for a stretchable, flexible and highly sensitive sensor able to detect a wide range of mechanically induced deformations. Herein, a physically cross-linked polylactic acid (PLA) and thermoplastic polyurethane (TPU) blend is made into nanofiber networks via electrospinning. The PLA/TPU weight ratio is optimized to obtain a maximum attainable strain of 100% while maintaining its mechanical integrity. The TPU/PLA fibers also allowed for their thermally activated recovery due to shape memory properties of the substrate. This novel feature enhances the sensor’s performance as it is no longer limited by its plastic deformation. Using spray coating method, a homogeneous layer of single-walled carbon nanotube is deposited onto the as-spun fiber mat to induce electrical conductivity to the surface of the fibers. It is shown that stretching and bending the sensor result in a highly sensitive and linear response with a maximum gauge factor of 33.

[Salmonella spp. strains resistant to drugs].

PubMed

Białucha, Agata; Kozuszko, Sylwia; Gospodarek, Eugenia

2010-01-01

The aim of the study was retrospective analysis of Salmonella spp. strains isolated from patients of State Infectious Diseases Observatory Hospital of T. Browicz in Bydgoszcz (SZAK) and University of dr. A. Jurasz in Bydgoszcz (SU CM UMK) in 2006-2009. The percentages of Salmonella spp. strains resistant to at least one drug were: 19,0% in 2006, 12,5% in 2007, 50,6% in 2008 and 43,8% in the first half of 2009 year. The highest number of Salmonella spp. strains resistant to drugs were isolated from stool (96,7%) and from patients of SZAK (83,3%). Among all isolated Salmonella spp. strains resistant to drugs the highest percentage were S. enterica serovar Enteritidis (56,7%). Among S. enterica bacilli predominated resitant phenotypes to ampicillin, amoxicillin, chloramphenicol and nalidixic acid. The increasing number of strains resistant to ciprofloxacin (0,0 - 26,7%) and high percentage of strains resistant to nalidixic acid (97,3%) were noted. Decreasing resistance to chloramphenicol was observed in our study (54,5 - 14,3%).

A closer look at prion strains

PubMed Central

Solforosi, Laura; Milani, Michela; Mancini, Nicasio; Clementi, Massimo; Burioni, Roberto

2013-01-01

Prions are infectious proteins that are responsible for transmissible spongiform encephalopathies (TSEs) and consist primarily of scrapie prion protein (PrPSc), a pathogenic isoform of the host-encoded cellular prion protein (PrPC). The absence of nucleic acids as essential components of the infectious prions is the most striking feature associated to these diseases. Additionally, different prion strains have been isolated from animal diseases despite the lack of DNA or RNA molecules. Mounting evidence suggests that prion-strain-specific features segregate with different PrPSc conformational and aggregation states. Strains are of practical relevance in prion diseases as they can drastically differ in many aspects, such as incubation period, PrPSc biochemical profile (e.g., electrophoretic mobility and glycoform ratio) and distribution of brain lesions. Importantly, such different features are maintained after inoculation of a prion strain into genetically identical hosts and are relatively stable across serial passages. This review focuses on the characterization of prion strains and on the wide range of important implications that the study of prion strains involves. PMID:23357828

A Strain Gauge Manual.

DTIC Science & Technology

1984-04-01

Applied Science Publications Ltd. (U.K.) "Strain Gauges, Kinds and Uses", H.K.P. Neubert . McMillan, London (U.K.) "A Strain Gauge Primer", Perry and...G.R. Paul (Materials) A.A. Baker (Materials) I.G. Powlesland G. Wright ." P. Ferrerotto J. Madej B. Ashcroft E.S. Moody M.T. Adams M. Cameron (GAF) (2

[The plasmid profile of Neisseria meningitidis strains].

PubMed

Khetsuriani, K G; Namgaladze, M Z; Lomsadze, Kh V; Kakuberi, D R

1993-01-01

The distribution of plasmids in N. meningitidis strains according to their origin and serological groups has been studied. Plasmids have been discovered in N. meningitidis of all groups, plasmid-carrying strains constituting 55% of strains isolated from healthy carriers and 46.2% of strains isolated from patients. The molecular weight of N. meningitidis plasmid DNA varies from 2.9 MD to 95 MD.

Load cell having strain gauges of arbitrary location

DOEpatents

Spletzer, Barry [Albuquerque, NM

2007-03-13

A load cell utilizes a plurality of strain gauges mounted upon the load cell body such that there are six independent load-strain relations. Load is determined by applying the inverse of a load-strain sensitivity matrix to a measured strain vector. The sensitivity matrix is determined by performing a multivariate regression technique on a set of known loads correlated to the resulting strains. Temperature compensation is achieved by configuring the strain gauges as co-located orthogonal pairs.

An unusual strain of Venezuelan encephalitis virus existing sympatrically with subtype I-D strains in a Peruvian rain forest.

PubMed

Scherer, W F; Chin, J

1983-07-01

In 1971, an unusual strain of Venezuelan encephalitis (VE) virus (71D1252) was recovered from the same small area of a rain forest in the western Amazon basin of South America near Iquitos, Loreto, Peru, from which strains of subtype I-D were recovered. The marker characteristics of this strain resembled most closely those of VE subtype III (Mucambo) and were distinctly different from coexisting I-D strains. Thus the concurrent presence of two different VE virus subtypes in one place was a striking exception to the usual geographic allopatry of VE virus subtypes. Strain 71D1252 also contained temperature sensitive (ts) (37 degrees C versus 39 degrees C) virions in the original mosquito suspension and first suckling mouse passage brain tissue suspensions. It thus represents one of the few so-far-reported ts strains of viruses found in nature, and the only natural ts strain of VE virus.

High-sensitivity strain visualization using electroluminescence technologies

NASA Astrophysics Data System (ADS)

Xu, Jian; Jo, Hongki

2016-04-01

Visualizing mechanical strain/stress changes is an emerging area in structural health monitoring. Several ways are available for strain change visualization through the color/brightness change of the materials subjected to the mechanical stresses, for example, using mechanoluminescence (ML) materials and mechanoresponsive polymers (MRP). However, these approaches were not effectively applicable for civil engineering system yet, due to insufficient sensitivity to low-level strain of typical civil structures and limitation in measuring both static and dynamic strain. In this study, design and validation for high-sensitivity strain visualization using electroluminescence technologies are presented. A high-sensitivity Wheatstone bridge, of which bridge balance is precisely controllable circuits, is used with a gain-adjustable amplifier. The monochrome electroluminescence (EL) technology is employed to convert both static and dynamic strain change into brightness/color change of the EL materials, through either brightness change mode (BCM) or color alternation mode (CAM). A prototype has been made and calibrated in lab, the linearity between strain and brightness change has been investigated.

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

NASA Astrophysics Data System (ADS)

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

2014-05-01

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

Comparative genome analysis of a large Dutch Legionella pneumophila strain collection identifies five markers highly correlated with clinical strains

PubMed Central

2010-01-01

Background Discrimination between clinical and environmental strains within many bacterial species is currently underexplored. Genomic analyses have clearly shown the enormous variability in genome composition between different strains of a bacterial species. In this study we have used Legionella pneumophila, the causative agent of Legionnaire's disease, to search for genomic markers related to pathogenicity. During a large surveillance study in The Netherlands well-characterized patient-derived strains and environmental strains were collected. We have used a mixed-genome microarray to perform comparative-genome analysis of 257 strains from this collection. Results Microarray analysis indicated that 480 DNA markers (out of in total 3360 markers) showed clear variation in presence between individual strains and these were therefore selected for further analysis. Unsupervised statistical analysis of these markers showed the enormous genomic variation within the species but did not show any correlation with a pathogenic phenotype. We therefore used supervised statistical analysis to identify discriminating markers. Genetic programming was used both to identify predictive markers and to define their interrelationships. A model consisting of five markers was developed that together correctly predicted 100% of the clinical strains and 69% of the environmental strains. Conclusions A novel approach for identifying predictive markers enabling discrimination between clinical and environmental isolates of L. pneumophila is presented. Out of over 3000 possible markers, five were selected that together enabled correct prediction of all the clinical strains included in this study. This novel approach for identifying predictive markers can be applied to all bacterial species, allowing for better discrimination between strains well equipped to cause human disease and relatively harmless strains. PMID:20630115

Poliovirus strain characterization: a WHO Memorandum*

PubMed Central

1980-01-01

Reliable laboratory techniques for the intratypic characterization of poliovirus types 1, 2, and 3 isolates have an important role in the epidemiological surveillance of poliomyelitis and in studies of the safety and efficacy of poliovirus vaccines. Of the techniques available for poliovirus strain characterization, those potentially most useful are intratypic serodifferentiation and the biochemical techniques. The value of strain-specific (absorbed) antisera for antigenic characterization of strains has been clearly established for the identification of both vaccine-like viruses and different epidemic wild strains. Single-radial-diffusion techniques appear to be promising and should be further explored. Biochemical techniques involving studies of both virus polypeptides and nucleic acids are also capable of providing valuable information for strain characterization. Biological and physico-chemical tests are generally of limited value but their application may be useful in certain circumstances. PMID:6170471

Skeletal muscle tensile strain dependence: hyperviscoelastic nonlinearity

PubMed Central

Wheatley, Benjamin B; Morrow, Duane A; Odegard, Gregory M; Kaufman, Kenton R; Donahue, Tammy L Haut

2015-01-01

Introduction Computational modeling of skeletal muscle requires characterization at the tissue level. While most skeletal muscle studies focus on hyperelasticity, the goal of this study was to examine and model the nonlinear behavior of both time-independent and time-dependent properties of skeletal muscle as a function of strain. Materials and Methods Nine tibialis anterior muscles from New Zealand White rabbits were subject to five consecutive stress relaxation cycles of roughly 3% strain. Individual relaxation steps were fit with a three-term linear Prony series. Prony series coefficients and relaxation ratio were assessed for strain dependence using a general linear statistical model. A fully nonlinear constitutive model was employed to capture the strain dependence of both the viscoelastic and instantaneous components. Results Instantaneous modulus (p<0.0005) and mid-range relaxation (p<0.0005) increased significantly with strain level, while relaxation at longer time periods decreased with strain (p<0.0005). Time constants and overall relaxation ratio did not change with strain level (p>0.1). Additionally, the fully nonlinear hyperviscoelastic constitutive model provided an excellent fit to experimental data, while other models which included linear components failed to capture muscle function as accurately. Conclusions Material properties of skeletal muscle are strain-dependent at the tissue level. This strain dependence can be included in computational models of skeletal muscle performance with a fully nonlinear hyperviscoelastic model. PMID:26409235

Superinfection Behaviors on Scale-Free Networks with Competing Strains

NASA Astrophysics Data System (ADS)

Wu, Qingchu; Small, Michael; Liu, Huaxiang

2013-02-01

This paper considers the epidemiology of two strains ( I, J) of a disease spreading through a population represented by a scale-free network. The epidemiological model is SIS and the two strains have different reproductive numbers. Superinfection means that strain I can infect individuals already infected with strain J, replacing the strain J infection. Individuals infected with strain I cannot be infected with strain J. The model is set up as a system of ordering differential equations and stability of the disease free, marginal strain I and strain J, and coexistence equilibria are assessed using linear stability analysis, supported by simulations. The main conclusion is that superinfection, as modeled in this paper, can allow strain I to coexist with strain J even when it has a lower basic reproductive number. Most strikingly, it can allow strain I to persist even when its reproductive number is less than 1.

Strain measurements in composite bolted-joint specimens

NASA Technical Reports Server (NTRS)

Hyer, M. W.; Lightfoot, M. C.; Perry, J. C.

1979-01-01

Strain data from a series of bolted joint tests is presented. Double lap, double hole, double lap, single hole, and open hole tensile specimens were tested and the strain gage locations, load strain responses, and load axial displacement responses are presented. The open hole specimens were gaged to determine strain concentration factors. The double lap, double hole specimens were gaged to determine the uniformity of the strain in the joint and the amount of load transferred past the first bolt. The measurements indicated roughly half the load passed the first bolt to be reacted by the second bolt.

Genome characterization of Turkey Rotavirus G strains from the United States identifies potential recombination events with human Rotavirus B strains.

PubMed

Chen, Fangzhou; Knutson, Todd P; Porter, Robert E; Ciarlet, Max; Mor, Sunil Kumar; Marthaler, Douglas G

2017-12-01

Rotavirus G (RVG) strains have been detected in a variety of avian species, but RVG genomes have been published from only a single pigeon and two chicken strains. Two turkey RVG strains were identified and characterized, one in a hatchery with no reported health issues and the other in a hatchery with high embryo/poult mortality. The two turkey RVG strains shared only an 85.3 % nucleotide sequence identity in the VP7 gene while the other genes possessed high nucleotide identity among them (96.3-99.9 %). Low nucleotide percentage identities (31.6-87.3 %) occurred among the pigeon and chicken RVG strains. Interestingly, potential recombination events were detected between our RVG strains and a human RVB strain, in the VP6 and NSP3 segments. The epidemiology of RVG in avian flocks and the pathogenicity of the two different RVG strains should be further investigated to understand the ecology and impact of RVG in commercial poultry flocks.

Static Strain Aging Behavior of a Manganese-Silicon Steel After Single and Multi-stage Straining

NASA Astrophysics Data System (ADS)

Seraj, P.; Serajzadeh, S.

2016-03-01

In this work, static strain aging behavior of an alloy steel containing high amounts of silicon and manganese was examined while the influences of initial microstructure and pre-strain on the aging kinetics were evaluated as well. The rate of strain aging in a low carbon steel was also determined and compared with that occurred in the alloy steel. The rates of static strain aging in the steels were defined at room temperature and at 95 °C by means of double-hit tensile testing and hardness measurements. In addition, three-stage aging experiments at 80 °C were carried out to estimate aging behavior under multi-pass deformation processing. The results showed that in-solution manganese and silicon atoms could significantly affect the aging behavior of the steel and reduce the kinetics of static strain aging as compared to the low carbon steel. The initial microstructure also played an important role on the aging behavior. The rapidly cooled steel having mean ferrite grain size of 9.7 μm showed the least aging susceptibility index during the aging experiments. Accordingly, the activation energies for static strain aging were calculated as 93.2 and 85.7 kJ/mole for the alloy steel having fine and coarse ferrite-pearlite structures, respectively while it was computed as 79.1 kJ/mole for the low carbon steel with ferrite mean grain size of about 16.2 μm.

Characterization of Bacteroides forsythus Strains from Cat and Dog Bite Wounds in Humans and Comparison with Monkey and Human Oral Strains

PubMed Central

Hudspeth, M. K.; Gerardo, S. Hunt; Maiden, M. F. J.; Citron, D. M.; Goldstein, E. J. C.

1999-01-01

Bacteroides forsythus strains recovered from cat and dog bite wound infections in humans (n = 3), monkey oral strains (n = 3), and the human oral ATCC 43037 type strain were characterized by using phenotypic characteristics, enzymatic tests, whole cell fatty acid analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis, PCR fingerprinting, and 16S rDNA (genes coding for rRNA) sequencing. All three bite wound isolates grew on brucella agar supplemented with 5% sheep blood, vitamin K1, and hemin. These strains, unlike the ATCC strain and previously described monkey oral and human clinical strains, did not require N-acetylmuramic acid supplementation for growth as pure cultures. However, their phenotypic characteristics, except for catalase production, were similar to those of previously identified strains. PCR fingerprinting analysis showed differences in band patterns from the ATCC strain. Also, SDS-PAGE and whole cell fatty acid analysis indicated that the dog and cat bite wound strains were similar but not identical to the human B. forsythus ATCC 43037 type strain and the monkey oral strains. The rDNA sequence analysis indicated that the three bite wound isolates had 99.93% homology with each other and 98.9 and 99.22% homology with the human ATCC 43037 and monkey oral strains, respectively. These results suggest that there are host-specific variations within each group. PMID:10325363

Job strain and older workers: Can a reduction in job strain help to eliminate the social security drain?

PubMed

Cahalin, Lawrence P

2009-01-01

Job strain is the psychological and physiological response to a lack of control or support in the work environment. It appears to be an important risk factor for continued employment throughout the lifespan. Reducing job strain earlier in a workers life has the potential to have substantial beneficial health effects throughout a workers life. Early screening for job strain should be implemented in known high risk or high strain jobs. This is particularly important since there a fewer younger workers entering the labor force and there will be a growing need for older workers to remain in the workforce. Furthermore, healthier workers will require less medical care and are likely to work longer if they are willing and able. Healthier older workers who are willing and able to work longer will defer receipt of retirement benefits while continuing to pay into the Social Security System. Further investigation of older individuals (1) willingness and motivation to work past the normal retirement age, (2) career and employment security, skills development, and reconciliation of working and non-working life, and (3) job strain and effects of reducing job strain is needed. The current job strain literature has been expanded to the Social Security System arena and suggests that reducing job strain has the potential to help eliminate the Social Security drain by increasing older worker labor force retention.

Comparative genome-scale modelling of Staphylococcus aureus strains identifies strain-specific metabolic capabilities linked to pathogenicity

PubMed Central

Bosi, Emanuele; Monk, Jonathan M.; Aziz, Ramy K.; Fondi, Marco; Nizet, Victor; Palsson, Bernhard Ø.

2016-01-01

Staphylococcus aureus is a preeminent bacterial pathogen capable of colonizing diverse ecological niches within its human host. We describe here the pangenome of S. aureus based on analysis of genome sequences from 64 strains of S. aureus spanning a range of ecological niches, host types, and antibiotic resistance profiles. Based on this set, S. aureus is expected to have an open pangenome composed of 7,411 genes and a core genome composed of 1,441 genes. Metabolism was highly conserved in this core genome; however, differences were identified in amino acid and nucleotide biosynthesis pathways between the strains. Genome-scale models (GEMs) of metabolism were constructed for the 64 strains of S. aureus. These GEMs enabled a systems approach to characterizing the core metabolic and panmetabolic capabilities of the S. aureus species. All models were predicted to be auxotrophic for the vitamins niacin (vitamin B3) and thiamin (vitamin B1), whereas strain-specific auxotrophies were predicted for riboflavin (vitamin B2), guanosine, leucine, methionine, and cysteine, among others. GEMs were used to systematically analyze growth capabilities in more than 300 different growth-supporting environments. The results identified metabolic capabilities linked to pathogenic traits and virulence acquisitions. Such traits can be used to differentiate strains responsible for mild vs. severe infections and preference for hosts (e.g., animals vs. humans). Genome-scale analysis of multiple strains of a species can thus be used to identify metabolic determinants of virulence and increase our understanding of why certain strains of this deadly pathogen have spread rapidly throughout the world. PMID:27286824

Step width alters iliotibial band strain during running.

PubMed

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

2012-11-01

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

Heterologous expression of the methyl carbamate-degrading hydrolase MCD.

PubMed

Naqvi, Tatheer; Cheesman, Matthew J; Williams, Michelle R; Campbell, Peter M; Ahmed, Safia; Russell, Robyn J; Scott, Colin; Oakeshott, John G

2009-10-26

The methyl carbamate-degrading hydrolase (MCD) of Achromobacter WM111 has considerable potential as a pesticide bioremediation agent. However this potential has been unrealisable until now because of an inability to express MCD in heterologous hosts such as Escherichia coli. Herein, we describe the first successful attempt to express appreciable quantities of MCD in active form in E. coli, and the subsequent characterisation of the heterologously expressed material. We find that the properties of this material closely match the previously reported properties of MCD produced from Achromobacter WM111. This includes the presence of two distinct forms of the enzyme that we show are most likely due to the presence of two functional translational start sites. The purified enzyme catalyses the hydrolysis of a carbamate (carbaryl), a carboxyl ester (alpha-naphthyl acetate) and a phophotriester (dimethyl umbelliferyl phosphate) and it is relatively resistant to thermal and solvent-mediated denaturation. The robust nature and catalytic promiscuity of MCD suggest that it could be exploited for various biotechnological applications.

Influence of strain on dislocation core in silicon

NASA Astrophysics Data System (ADS)

Pizzagalli, L.; Godet, J.; Brochard, S.

2018-05-01

First principles, density functional-based tight binding and semi-empirical interatomic potentials calculations are performed to analyse the influence of large strains on the structure and stability of a 60? dislocation in silicon. Such strains typically arise during the mechanical testing of nanostructures like nanopillars or nanoparticles. We focus on bi-axial strains in the plane normal to the dislocation line. Our calculations surprisingly reveal that the dislocation core structure largely depends on the applied strain, for strain levels of about 5%. In the particular case of bi-axial compression, the transformation of the dislocation to a locally disordered configuration occurs for similar strain magnitudes. The formation of an opening, however, requires larger strains, of about 7.5%. Furthermore, our results suggest that electronic structure methods should be favoured to model dislocation cores in case of large strains whenever possible.

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

USDA-ARS?s Scientific Manuscript database

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...

Strain driven sequential magnetic transitions in strained GdTiO3 on compressive substrates: a first-principles study.

PubMed

Yang, Li-Juan; Weng, Ya-Kui; Zhang, Hui-Min; Dong, Shuai

2014-11-26

The compressive strain effect on the magnetic ground state and electronic structure of strained GdTiO3 has been studied using the first-principles method. Unlike the cases of congeneric YTiO3 and LaTiO3, both of which become the A-type antiferromagnetism on the (0 0 1) LaAlO3 substrate despite their contrastive magnetism, the ground state of strained GdTiO3 on the LaAlO3 substrate changes from the original ferromagnetism to a G-type antiferromagnetim, instead of the A-type one although Gd(3+) is between Y(3+) and La(3+). It is only when the in-plane compressive strain is large enough, e.g. on the (0 0 1) YAlO3 substrate, that the ground state finally becomes the A-type. The band structure calculation shows that the compressive strained GdTiO3 remains insulating, although the band gap changes a little in the strained GdTiO3.

Longitudinal and Circumferential Strain of the Proximal Aorta

PubMed Central

Bell, Vanessa; Mitchell, William A.; Sigurðsson, Sigurður; Westenberg, Jos J. M.; Gotal, John D.; Torjesen, Alyssa A.; Aspelund, Thor; Launer, Lenore J.; de Roos, Albert; Gudnason, Vilmundur; Harris, Tamara B.; Mitchell, Gary F.

2014-01-01

Background Accurate assessment of mechanical properties of the proximal aorta is a requisite first step for elucidating the pathophysiology of isolated systolic hypertension. During systole, substantial proximal aortic axial displacement produces longitudinal strain, which we hypothesize causes variable underestimation of ascending aortic circumferential strain compared to values in the longitudinally constrained descending aorta. Methods and Results To assess effects of longitudinal strain, we performed magnetic resonance imaging in 375 participants (72 to 94 years old, 204 women) in the Age, Gene/Environment Susceptibility‐Reykjavik Study and measured aortic circumferential and longitudinal strain. Circumferential ascending aortic area strain uncorrected for longitudinal strain was comparable in women and men (mean [95% CI], 8.3 [7.8, 8.9] versus 7.9 [7.4, 8.5]%, respectively, P=0.3). However, longitudinal strain was greater in women (8.5±2.5 versus 7.0±2.5%, P<0.001), resulting in greater longitudinally corrected circumferential ascending aortic strain (14.4 [13.6, 15.2] versus 13.0 [12.4, 13.7]%, P=0.010). Observed circumferential descending aortic strain, which did not require correction (women: 14.0 [13.2, 14.8], men: 12.4 [11.6, 13.2]%, P=0.005), was larger than uncorrected (P<0.001), but comparable to longitudinally corrected (P=0.12) circumferential ascending aortic strain. Carotid‐femoral pulse wave velocity did not correlate with uncorrected ascending aortic strain (R=−0.04, P=0.5), but was inversely related to longitudinally corrected ascending and observed descending aortic strain (R=−0.15, P=0.004; R=−0.36, P<0.001, respectively). Longitudinal strain was also inversely related to carotid‐femoral pulse wave velocity and other risk factors for higher aortic stiffness including treated hypertension. Conclusions Longitudinal strain creates substantial and variable errors in circumferential ascending aortic area strain measurements

Taxonomy of oxalotrophic Methylobacterium strains.

PubMed

Sahin, Nurettin; Kato, Yuko; Yilmaz, Ferah

2008-10-01

Most of the oxalotrophic bacteria are facultative methylotrophs and play important ecological roles in soil fertility and cycling of elements. This study gives a detailed picture of the taxonomy and diversity of these bacteria and provides new information about the taxonomical variability within the genus Methylobacterium. Twelve mesophilic, pink-pigmented, and facultatively methylotrophic oxalate-oxidizing strains were included in this work that had been previously isolated from the soil and some plant tissues by the potassium oxalate enrichment method. The isolates were characterized using biochemical tests, cellular lipid profiles, spectral characteristics of carotenoid pigments, G+C content of the DNA, and 16S rDNA sequencing. The taxonomic similarities among the strains were analyzed using the simple matching (S (SM)) and Jaccard (S (J)) coefficients, and the UPGMA clustering algorithm. The phylogenetic position of the strains was inferred by the neighbor-joining method on the basis of the 16S rDNA sequences. All isolates were Gram-negative, facultatively methylotrophic, oxidase and catalase positive, and required no growth factors. Based on the results of numerical taxonomy, the strains formed four closely related clusters sharing > or =85% similarity. Analysis of the 16S rDNA sequences demonstrated that oxalotrophic, pink-pigmented, and facultatively methylotrophic strains could be identified as members of the genus Methylobacterium. Except for M. variabile and M. aquaticum, all of the Methylobacterium type strains tested had the ability of oxalate utilization. Our results indicate that the capability of oxalate utilization seems to be an uncommon trait and could be used as a valuable taxonomic criterion for differentiation of Methylobacterium species.

Taxonomy of oxalotrophic Methylobacterium strains

NASA Astrophysics Data System (ADS)

Sahin, Nurettin; Kato, Yuko; Yilmaz, Ferah

2008-10-01

Most of the oxalotrophic bacteria are facultative methylotrophs and play important ecological roles in soil fertility and cycling of elements. This study gives a detailed picture of the taxonomy and diversity of these bacteria and provides new information about the taxonomical variability within the genus Methylobacterium. Twelve mesophilic, pink-pigmented, and facultatively methylotrophic oxalate-oxidizing strains were included in this work that had been previously isolated from the soil and some plant tissues by the potassium oxalate enrichment method. The isolates were characterized using biochemical tests, cellular lipid profiles, spectral characteristics of carotenoid pigments, G+C content of the DNA, and 16S rDNA sequencing. The taxonomic similarities among the strains were analyzed using the simple matching ( S SM) and Jaccard ( S J) coefficients, and the UPGMA clustering algorithm. The phylogenetic position of the strains was inferred by the neighbor-joining method on the basis of the 16S rDNA sequences. All isolates were Gram-negative, facultatively methylotrophic, oxidase and catalase positive, and required no growth factors. Based on the results of numerical taxonomy, the strains formed four closely related clusters sharing ≥85% similarity. Analysis of the 16S rDNA sequences demonstrated that oxalotrophic, pink-pigmented, and facultatively methylotrophic strains could be identified as members of the genus Methylobacterium. Except for M. variabile and M. aquaticum, all of the Methylobacterium type strains tested had the ability of oxalate utilization. Our results indicate that the capability of oxalate utilization seems to be an uncommon trait and could be used as a valuable taxonomic criterion for differentiation of Methylobacterium species.

Numerical modelling of strain in lava tubes

NASA Astrophysics Data System (ADS)

Merle, Olivier

The strain within lava tubes is described in terms of pipe flow. Strain is partitioned into three components: (a) two simple shear components acting from top to bottom and from side to side of a rectangular tube in transverse section; and (b) a pure shear component corresponding to vertical shortening in a deflating flow and horizontal compression in an inflating flow. The sense of shear of the two simple shear components is reversed on either side of a central zone of no shear. Results of numerical simulations of strain within lava tubes reveal a concentric pattern of flattening planes in section normal to the flow direction. The central node is a zone of low strain, which increases toward the lateral borders. Sections parallel to the flow show obliquity of the flattening plane to the flow axis, constituting an imbrication. The strain ellipsoid is generally of plane strain type, but can be of constriction or flattening type if thinning (i.e. deflating flow) or thickening (i.e. inflating flow) is superimposed on the simple shear regime. The strain pattern obtained from numerical simulation is then compared with several patterns recently described in natural lava flows. It is shown that the strain pattern revealed by AMS studies or crystal preferred orientations is remarkably similar to the numerical simulation. However, some departure from the model is found in AMS measurements. This may indicate inherited strain recorded during early stages of the flow or some limitation of the AMS technique.

Anomic Strain and External Constraints: A Reassessment of Merton's Anomie/Strain Theory Using Data From Ukraine.

PubMed

Antonaccio, Olena; Smith, William R; Gostjev, Feodor A

2015-09-01

This study provides a new assessment of Merton's anomie/strain theory and fills in several gaps in the literature. First, using the data from the sample of adolescents in an especially suitable and interesting setting, post-Soviet Ukraine, it investigates the applicability of the theory to this context and reveals that predictive powers of anomic strain may be influenced by larger sociocultural environments. Second, it evaluates the possibility of theoretical elaboration of Merton's theory through identifying contingencies such as external constraints on behavior and finds limited support for moderating effects of perceptions of risks of sanctioning and social bonds on anomic strain-delinquency relationships. Finally, it confirms that additional clarifications of the concept of anomic strain may be promising. © The Author(s) 2014.

The many shades of prion strain adaptation.

PubMed

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.

Left atrial function: evaluation by strain analysis

PubMed Central

Gan, Gary C. H.; Ferkh, Aaisha; Boyd, Anita

2018-01-01

The left atrium has an important role in modulating left ventricular filling and is an important biomarker of cardiovascular disease and adverse cardiovascular outcomes. While previously left atrial (LA) size was utilised, the role of LA function as a biomarker is increasingly being evaluated, both independently and also in combination with LA size. Strain analysis has been utilised for evaluation of LA function and can be measured throughout the cardiac cycle, thereby enabling the evaluation of LA reservoir, conduit and contractile function. Strain evaluates myocardial deformation while strain rate examines the rate of change in strain. This review will focus on the various types of strain analysis for evaluation of LA function, alterations in LA strain in physiological and pathologic states that alter LA function and finally evaluate its utility as a prognostic marker. PMID:29541609

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

ERIC Educational Resources Information Center

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

2003-01-01

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

Regulation of Anabaena sp. strain PCC 7120 glutamine synthetase activity in a Synechocystis sp. strain PCC 6803 derivative strain bearing the Anabaena glnA gene and a mutated host glnA gene.

PubMed Central

Mérida, A; Flores, E; Florencio, F J

1992-01-01

The glnA gene from Synechocystis sp. strain PCC 6803 was cloned by hybridization with the glnA gene from Anabaena sp. strain PCC 7120, and a deletion-insertion mutation of the Synechocystis gene was generated in vitro. A strain derived from Synechocystis sp. strain PCC 6803 which contained integrated into the chromosome, in addition to its own glnA gene, the Anabaena glnA gene was constructed. From that strain, a Synechocystis sp. glnA mutant could be obtained by transformation with the inactivated Synechocystis glnA gene; this mutant grew by using Anabaena glutamine synthetase and was not a glutamine auxotroph. A Synechocystis sp. glnA mutant could not be obtained, however, from the wild-type Synechocystis sp. The Anabaena glutamine synthetase enzyme was subject to ammonium-promoted inactivation when expressed in the Synechocystis strain but not in the Anabaena strain itself. Images PMID:1345914

Second Generation Models for Strain-Based Design

DOT National Transportation Integrated Search

2011-08-30

This project covers the development of tensile strain design models which form a key part of the strain-based design of pipelines. The strain-based design includes at least two limit states, tensile rupture, and compressive buckling. The tensile stra...

Strain features and condition assessment of orthotropic steel deck cable-supported bridges subjected to vehicle loads by using dense FBG strain sensors

NASA Astrophysics Data System (ADS)

Wei, Shiyin; Zhang, Zhaohui; Li, Shunlong; Li, Hui

2017-10-01

Strain is a direct indicator of structural safety. Therefore, strain sensors have been used in most structural health monitoring systems for bridges. However, until now, the investigation of strain response has been insufficient. This paper conducts a comprehensive study of the strain features of the U ribs and transverse diaphragm on an orthotropic steel deck and proposes a statistical paradigm for crack detection based on the features of vehicle-induced strain response by using the densely distributed optic fibre Bragg grating (FBG) strain sensors. The local feature of strain under vehicle load is highlighted, which enables the use of measurement data to determine the vehicle loading event and to make a decision regarding the health status of a girder near the strain sensors via technical elimination of the load information. Time-frequency analysis shows that the strain contains three features: the long-term trend item, the short-term trend item, and the instantaneous vehicle-induced item (IVII). The IVII is the wheel-induced strain with a remarkable local feature, and the measured wheel-induced strain is only influenced by the vehicle near the FBG sensor, while other vehicles slightly farther away have no effect on the wheel-induced strain. This causes the local strain series, among the FBG strain sensors in the same transverse locations of different cross-sections, to present similarities in shape to some extent and presents a time delay in successive order along the driving direction. Therefore, the strain series induced by an identical vehicle can be easily tracked and compared by extracting the amplitude and calculating the mutual ratio to eliminate vehicle loading information, leaving the girder information alone. The statistical paradigm for crack detection is finally proposed, and the detection accuracy is then validated by using dense FBG strain sensors on a long-span suspension bridge in China.

Comparative Proteome Analysis of Brucella melitensis Vaccine Strain Rev 1 and a Virulent Strain, 16M

PubMed Central

Eschenbrenner, Michel; Wagner, Mary Ann; Horn, Troy A.; Kraycer, Jo Ann; Mujer, Cesar V.; Hagius, Sue; Elzer, Philip; DelVecchio, Vito G.

2002-01-01

The genus Brucella consists of bacterial pathogens that cause brucellosis, a major zoonotic disease characterized by undulant fever and neurological disorders in humans. Among the different Brucella species, Brucella melitensis is considered the most virulent. Despite successful use in animals, the vaccine strains remain infectious for humans. To understand the mechanism of virulence in B. melitensis, the proteome of vaccine strain Rev 1 was analyzed by two-dimensional gel electrophoresis and compared to that of virulent strain 16M. The two strains were grown under identical laboratory conditions. Computer-assisted analysis of the two B. melitensis proteomes revealed proteins expressed in either 16M or Rev 1, as well as up- or down-regulation of proteins specific for each of these strains. These proteins were identified by peptide mass fingerprinting. It was found that certain metabolic pathways may be deregulated in Rev 1. Expression of an immunogenic 31-kDa outer membrane protein, proteins utilized for iron acquisition, and those that play a role in sugar binding, lipid degradation, and amino acid binding was altered in Rev 1. PMID:12193611

Comparative proteome analysis of Brucella melitensis vaccine strain Rev 1 and a virulent strain, 16M.

PubMed

Eschenbrenner, Michel; Wagner, Mary Ann; Horn, Troy A; Kraycer, Jo Ann; Mujer, Cesar V; Hagius, Sue; Elzer, Philip; DelVecchio, Vito G

2002-09-01

The genus Brucella consists of bacterial pathogens that cause brucellosis, a major zoonotic disease characterized by undulant fever and neurological disorders in humans. Among the different Brucella species, Brucella melitensis is considered the most virulent. Despite successful use in animals, the vaccine strains remain infectious for humans. To understand the mechanism of virulence in B. melitensis, the proteome of vaccine strain Rev 1 was analyzed by two-dimensional gel electrophoresis and compared to that of virulent strain 16M. The two strains were grown under identical laboratory conditions. Computer-assisted analysis of the two B. melitensis proteomes revealed proteins expressed in either 16M or Rev 1, as well as up- or down-regulation of proteins specific for each of these strains. These proteins were identified by peptide mass fingerprinting. It was found that certain metabolic pathways may be deregulated in Rev 1. Expression of an immunogenic 31-kDa outer membrane protein, proteins utilized for iron acquisition, and those that play a role in sugar binding, lipid degradation, and amino acid binding was altered in Rev 1.

Pheromonal divergence between two strains of Spodoptera frugiperda

USDA-ARS?s Scientific Manuscript database

Abstract- 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...

Trypanosoma cruzi: clones isolated from the Colombian strain, reproduce the parental strain characteristics, with ubiquitous histotropism

PubMed Central

Camandaroba, Edson; Thé, Torriceli S; Pessina, Daniel Huber; Andrade, Sonia G

2006-01-01

Clonal histotropism and biological characters of five clones isolated during the early acute phase of the infection of Swiss mice with the Colombian strain of Trypanosoma cruzi (T. cruzi I), Biodeme Type III, were investigated. Clones were isolated from mice at the 10th and the 30th day of infection with the Colombian strain. Isolation was performed by micromanipulation and injection of one trypomatigote blood form into newborn mice, followed by passages into suckling mice for obtaining the inocula for the experimental groups. Mice infected with parental strain were also studied. All the clones have shown the basic characteristics of Biodeme Type III, with the same patterns of parasitemia, tissue tropism, morphological characters and isoenzymic profiles, such as the parental strain. Histotropism was most intense to myocardium and skeletal muscles, with intense lesions found in the advanced phase (20th to 30th day of infection). Both parental strain and the clones were seen to parasitize several organs and tissues; amastigote nests were identified in the cytoplasm of macrophages, adipose cells, smooth muscle of intestinal wall and Auerbach's neuronal plexus. The findings of the present study confirm the homology of the clones isolated from the Colombian strain, with predominance of a ‘principal clone’ and an ubiquitous distribution of parasites belonging to a same clone. PMID:16709229

High-Temperature Adhesive Strain Gage Developed

NASA Technical Reports Server (NTRS)

Pereira, J. Michael; Roberts, Gary D.

1997-01-01

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

Efficient characterization of inhomogeneity in contraction strain pattern.

PubMed

Nazzal, Christina M; Mulligan, Lawrence J; Criscione, John C

2012-05-01

Cardiac dyssynchrony often accompanies patients with heart failure (HF) and can lead to an increase in mortality rate. Cardiac resynchronization therapy (CRT) has been shown to provide substantial benefits to the HF population with ventricular dyssynchrony; however, there still exists a group of patients who do not respond to this treatment. In order to better understand patient response to CRT, it is necessary to quantitatively characterize both electrical and mechanical dyssynchrony. The quantification of mechanical dyssynchrony via characterization of contraction strain field inhomogeneity is the focus of this modeling investigation. Raw data from a 3D finite element (FE) model were received from Roy Kerckhoffs et al. and analyzed in MATLAB. The FE model consisted of canine left and right ventricles coupled to a closed circulation with the effects of the pericardium acting as a pressure on the epicardial surface. For each of three simulations (normal synchronous, SYNC, right ventricular apical pacing, RVA, and left ventricular free wall pacing, LVFW) the Gauss point locations and values were used to generate lookup tables (LUTs) with each entry representing a location in the heart. In essence, we employed piecewise cubic interpolation to generate a fine point cloud (LUTs) from a course point cloud (Gauss points). Strain was calculated in the fiber direction and was then displayed in multiple ways to better characterize strain inhomogeneity. By plotting average strain and standard deviation over time, the point of maximum contraction and the point of maximal inhomogeneity were found for each simulation. Strain values were organized into seven strain bins to show operative strain ranges and extent of inhomogeneity throughout the heart wall. In order to visualize strain propagation, magnitude, and inhomogeneity over time, we created 2D area maps displaying strain over the entire cardiac cycle. To visualize spatial strain distribution at the time point of maximum

Method of transferring strained semiconductor structure

DOEpatents

Nastasi, Michael A [Santa Fe, NM; Shao, Lin [College Station, TX

2009-12-29

The transfer of strained semiconductor layers from one substrate to another substrate involves depositing a multilayer structure on a substrate having surface contaminants. An interface that includes the contaminants is formed in between the deposited layer and the substrate. Hydrogen atoms are introduced into the structure and allowed to diffuse to the interface. Afterward, the deposited multilayer structure is bonded to a second substrate and is separated away at the interface, which results in transferring a multilayer structure from one substrate to the other substrate. The multilayer structure includes at least one strained semiconductor layer and at least one strain-induced seed layer. The strain-induced seed layer can be optionally etched away after the layer transfer.

Whole Genome Analysis of a Wine Yeast Strain

PubMed Central

Hauser, Nicole C.; Fellenberg, Kurt; Gil, Rosario; Bastuck, Sonja; Hoheisel, Jörg D.

2001-01-01

Saccharomyces cerevisiae strains frequently exhibit rather specific phenotypic features needed for adaptation to a special environment. Wine yeast strains are able to ferment musts, for example, while other industrial or laboratory strains fail to do so. The genetic differences that characterize wine yeast strains are poorly understood, however. As a first search of genetic differences between wine and laboratory strains, we performed DNA-array analyses on the typical wine yeast strain T73 and the standard laboratory background in S288c. Our analysis shows that even under normal conditions, logarithmic growth in YPD medium, the two strains have expression patterns that differ significantly in more than 40 genes. Subsequent studies indicated that these differences correlate with small changes in promoter regions or variations in gene copy number. Blotting copy numbers vs. transcript levels produced patterns, which were specific for the individual strains and could be used for a characterization of unknown samples. PMID:18628902

Live Streptococcus suis type 5 strain XS045 provides cross-protection against infection by strains of types 2 and 9.

PubMed

Jiang, Xiaowu; Yang, Yunkai; Zhu, Lexin; Gu, Yuanxing; Shen, Hongxia; Shan, Ying; Li, Xiaoliang; Wu, Jiusheng; Fang, Weihuan

2016-12-12

Streptococcus suis is one of the common pathogens causing diseases in pigs and covers 35 serotypes with the type 2 strains being more pathogenic and zoonotic. Existing inactivated or subunit vaccines, in clinical use or under trial, could not provide cross protection against other serotypes. We identified a natural low-virulence S. suis type 5 strain XS045 as a live vaccine candidate because it is highly adhesive to the cultured HEp-2 cells, but with no apparent pathogenicity in mice and piglets. We further demonstrate that subcutaneous administration of the live XS045 strain to mice induced high antibody responses and was able to provide cross protection against challenges by a type 2 strain HA9801 (100% protection) and a type 9 strain JX13 (85% protection). Induction of high-titer antibodies with opsonizing activity as well as their cross-reactivity to surface proteins of the types 2 and 9 strains and anti-adhesion effect could be the mechanisms of cross protection. This is the first report that a live vaccine candidate S. suis type 5 strain could induce cross-protection against strains of types 2 and 9. This candidate strain is to be further examined for safety in pigs of different ages and breeds as well as for its protection against other serotypes or other strains of the type 2, a serotype of particular importance from public health concern. Copyright © 2016 Elsevier Ltd. All rights reserved.

Genome characterization of a novel binary toxin-positive strain of Clostridium difficile and comparison with the epidemic 027 and 078 strains.

PubMed

Peng, Zhong; Liu, Sidi; Meng, Xiujuan; Liang, Wan; Xu, Zhuofei; Tang, Biao; Wang, Yuanguo; Duan, Juping; Fu, Chenchao; Wu, Bin; Wu, Anhua; Li, Chunhui

2017-01-01

Clostridium difficile is an anaerobic Gram-positive spore-forming gut pathogen that causes antibiotic-associated diarrhea worldwide. A small number of C. difficile strains express the binary toxin (CDT), which is generally found in C. difficile 027 (ST1) and/or 078 (ST11) in clinic. However, we isolated a binary toxin-positive non-027, non-078 C. difficile LC693 that is associated with severe diarrhea in China. The genotype of this strain was determined as ST201. To understand the pathogenesis-basis of C. difficile ST201, the strain LC693 was chosen for whole genome sequencing, and its genome sequence was analyzed together with the other two ST201 strains VL-0104 and VL-0391 and compared to the epidemic 027/ST1 and 078/ST11 strains. The project finally generated an estimated genome size of approximately 4.07 Mbp for strain LC693. Genome size of the three ST201 strains ranged from 4.07 to 4.16 Mb, with an average GC content between 28.5 and 28.9%. Phylogenetic analysis demonstrated that the ST201 strains belonged to clade 3. The ST201 genomes contained more than 40 antibiotic resistance genes and 15 of them were predicted to be associated with vancomycin-resistance. The ST201 strains contained a larger PaLoc with a Tn6218 element inserted than the 027/ST1 and 078/ST11 strains, and encoded a truncated TcdC. In addition, the ST201 strains contained intact binary toxin coding and regulation genes which are highly homologous to the 027/ST1 strain. Genome comparison of the ST201 strains with the epidemic 027 and 078 strain identified 641 genes specific for C. difficile ST201, and a number of them were predicted as fitness and virulence associated genes. The presence of those genes also contributes to the pathogenesis of the ST201 strains. In this study, the genomic characterization of three binary toxin-positive C. difficile ST201 strains in clade 3 was discussed and compared to the genomes of the epidemic 027 and the 078 strains. Our analysis identified a number

An investigation of strain cycling behavior of 7075-T6 aluminum under combined state of strain: The effects of out-of-phase, biaxial strain cycling on low cycle fatigue

NASA Technical Reports Server (NTRS)

Zamrik, S. Y.

1972-01-01

The effect of out-of-phase strain cycling on the low cycle fatigue of biaxially loaded specimens is discussed. A method to apply phase angles between two strains imposed in two different directions was developed. The data and the proposed theoretical analysis are part of a research program on biaxial strain cycling effect on fatigue life of structural materials.

Laser-induced photo-thermal strain imaging

NASA Astrophysics Data System (ADS)

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

2018-02-01

Vulnerable plaque is the one of the leading causes of cardiovascular disease occurrence. However, conventional intravascular imaging techniques suffer from difficulty in finding vulnerable plaque due to limitation such as lack of physiological information, imaging depth, and depth sensitivity. Therefore, new techniques are needed to help determine the vulnerability of plaque, Thermal strain imaging (TSI) is an imaging technique based on ultrasound (US) wave propagation speed that varies with temperature of medium. During temperature increase, strain occurs in the medium and its variation tendency is depending on the type of tissue, which makes it possible to use for tissue differentiation. Here, we demonstrate laser-induced photo-thermal strain imaging (pTSI) to differentiate tissue using an intravascular ultrasound (IVUS) catheter and a 1210-nm continuous-wave laser for heating lipids intensively. During heating, consecutive US images were obtained from a custom-made phantom made of porcine fat and gelatin. A cross correlation-based speckle-tracking algorithm was then applied to calculate the strain of US images. In the strain images, the positive strain produced in lipids (porcine fat) was clearly differentiated from water-bearing tissue (gelatin). This result shows that laser-induced pTSI could be a new method to distinguish lipids in the plaque and can help to differentiate vulnerability of plaque.

Strain-controlled electrocatalysis on multimetallic nanomaterials

NASA Astrophysics Data System (ADS)

Luo, Mingchuan; Guo, Shaojun

2017-11-01

Electrocatalysis is crucial for the development of clean and renewable energy technologies, which may reduce our reliance on fossil fuels. Multimetallic nanomaterials serve as state-of-the-art electrocatalysts as a consequence of their unique physico-chemical properties. One method of enhancing the electrocatalytic performance of multimetallic nanomaterials is to tune or control the surface strain of the nanomaterials, and tremendous progress has been made in this area in the past decade. In this Review, we summarize advances in the introduction, tuning and quantification of strain in multimetallic nanocrystals to achieve more efficient energy conversion by electrocatalysis. First, we introduce the concept of strain and its correlation with other key physico-chemical properties. Then, using the electrocatalytic reduction of oxygen as a model reaction, we discuss the underlying mechanisms behind the strain-adsorption-reactivity relationship based on combined classical theories and models. We describe how this knowledge can be harnessed to design multimetallic nanocrystals with optimized strain to increase the efficiency of oxygen reduction. In particular, we highlight the unexpectedly beneficial (and previously overlooked) role of tensile strain from multimetallic nanocrystals in improving electrocatalysis. We conclude by outlining the challenges and offering our perspectives on the research directions in this burgeoning field.

Inexpensive Implementation of Many Strain Gauges

NASA Technical Reports Server (NTRS)

Berkun, Andrew C.

2010-01-01

It has been proposed to develop arrays of strain gauges as arrays of ordinary metal film resistors and associated electronic readout circuitry on printed circuit boards or other suitable substrates. This proposal is a by-product of a development of instrumentation utilizing metal film resistors on printed-circuit boards to measure temperatures at multiple locations. In the course of that development, it was observed that in addition to being sensitive to temperature, the metal film resistors were also sensitive to strains in the printed-circuit boards to which they were attached. Because of the low cost of ordinary metal film resistors (typically <$0.01 apiece at 2007 prices), the proposal could enable inexpensive implementation of arrays of many (e.g., 100 or more) strain gauges, possibly concentrated in small areas. For example, such an array could be designed for use as a computer keyboard with no moving parts, as a device for sensing the shape of an object resting on a surface, or as a device for measuring strains at many points on a mirror, a fuel tank, an airplane wing, or other large object. Ordinarily, the effect of strain on resistance would be regarded as a nuisance in a temperature-measuring application, and the effect of temperature on resistance would be regarded as a nuisance in a strain-measuring application. The strain-induced changes in resistance of the metal film resistors in question are less than those of films in traditional strain gauges. The main novel aspect of present proposal lies in the use of circuitry affording sufficient sensitivity to measure strain plus means for compensating for the effect of temperature. For an array of metal film resistors used as proposed, the readout circuits would include a high-accuracy analog-to-digital converter fed by a low noise current source, amplifier chain, and an analog multiplexer chain. Corrections would be provided by use of high-accuracy calibration resistors and a temperature sensor. By use of

Transcriptomics-based strain optimization tool for designing secondary metabolite overproducing strains of Streptomyces coelicolor.

PubMed

Kim, Minsuk; Yi, Jeong Sang; Lakshmanan, Meiyappan; Lee, Dong-Yup; Kim, Byung-Gee

2016-03-01

In silico model-driven analysis using genome-scale model of metabolism (GEM) has been recognized as a promising method for microbial strain improvement. However, most of the current GEM-based strain design algorithms based on flux balance analysis (FBA) heavily rely on the steady-state and optimality assumptions without considering any regulatory information. Thus, their practical usage is quite limited, especially in its application to secondary metabolites overproduction. In this study, we developed a transcriptomics-based strain optimization tool (tSOT) in order to overcome such limitations by integrating transcriptomic data into GEM. Initially, we evaluated existing algorithms for integrating transcriptomic data into GEM using Streptomyces coelicolor dataset, and identified iMAT algorithm as the only and the best algorithm for characterizing the secondary metabolism of S. coelicolor. Subsequently, we developed tSOT platform where iMAT is adopted to predict the reaction states, and successfully demonstrated its applicability to secondary metabolites overproduction by designing actinorhodin (ACT), a polyketide antibiotic, overproducing strain of S. coelicolor. Mutants overexpressing tSOT targets such as ribulose 5-phosphate 3-epimerase and NADP-dependent malic enzyme showed 2 and 1.8-fold increase in ACT production, thereby validating the tSOT prediction. It is expected that tSOT can be used for solving other metabolic engineering problems which could not be addressed by current strain design algorithms, especially for the secondary metabolite overproductions. © 2015 Wiley Periodicals, Inc.

Strain driven sequential magnetic transitions in strained GdTiO3 on compressive substrates: a first-principles study

NASA Astrophysics Data System (ADS)

Yang, Li-Juan; Weng, Ya-Kui; Zhang, Hui-Min; Dong, Shuai

2014-11-01

The compressive strain effect on the magnetic ground state and electronic structure of strained GdTiO3 has been studied using the first-principles method. Unlike the cases of congeneric YTiO3 and LaTiO3, both of which become the A-type antiferromagnetism on the (0 0 1) LaAlO3 substrate despite their contrastive magnetism, the ground state of strained GdTiO3 on the LaAlO3 substrate changes from the original ferromagnetism to a G-type antiferromagnetim, instead of the A-type one although Gd3+ is between Y3+ and La3+. It is only when the in-plane compressive strain is large enough, e.g. on the (0 0 1) YAlO3 substrate, that the ground state finally becomes the A-type. The band structure calculation shows that the compressive strained GdTiO3 remains insulating, although the band gap changes a little in the strained GdTiO3.

Breeding of a xylose-fermenting hybrid strain by mating genetically engineered haploid strains derived from industrial Saccharomyces cerevisiae.

PubMed

Inoue, Hiroyuki; Hashimoto, Seitaro; Matsushika, Akinori; Watanabe, Seiya; Sawayama, Shigeki

2014-12-01

The industrial Saccharomyces cerevisiae IR-2 is a promising host strain to genetically engineer xylose-utilizing yeasts for ethanol fermentation from lignocellulosic hydrolysates. Two IR-2-based haploid strains were selected based upon the rate of xylulose fermentation, and hybrids were obtained by mating recombinant haploid strains harboring heterogeneous xylose dehydrogenase (XDH) (wild-type NAD(+)-dependent XDH or engineered NADP(+)-dependent XDH, ARSdR), xylose reductase (XR) and xylulose kinase (XK) genes. ARSdR in the hybrids selected for growth rates on yeast extract-peptone-dextrose (YPD) agar and YP-xylose agar plates typically had a higher activity than NAD(+)-dependent XDH. Furthermore, the xylose-fermenting performance of the hybrid strain SE12 with the same level of heterogeneous XDH activity was similar to that of a recombinant strain of IR-2 harboring a single set of genes, XR/ARSdR/XK. These results suggest not only that the recombinant haploid strains retain the appropriate genetic background of IR-2 for ethanol production from xylose but also that ARSdR is preferable for xylose fermentation.

Systems and Methods for Implementing Bulk Metallic Glass-Based Strain Wave Gears and Strain Wave Gear Components

NASA Technical Reports Server (NTRS)

Hofmann, Douglas C. (Inventor); Wilcox, Brian (Inventor)

2016-01-01

Bulk metallic glass-based strain wave gears and strain wave gear components. In one embodiment, a strain wave gear includes: a wave generator; a flexspline that itself includes a first set of gear teeth; and a circular spline that itself includes a second set of gear teeth; where at least one of the wave generator, the flexspline, and the circular spline, includes a bulk metallic glass-based material.

Forming Ganymede's grooves at smaller strain: Toward a self-consistent local and global strain history for Ganymede

NASA Astrophysics Data System (ADS)

Bland, Michael T.; McKinnon, William B.

2015-01-01

The ubiquity of tectonic features formed in extension, and the apparent absence of ones formed in contraction, has led to the hypothesis that Ganymede has undergone global expansion in its past. Determining the magnitude of such expansion is challenging however, and extrapolation of locally or regionally inferred strains to global scales often results in strain estimates that exceed those based on global constraints. Here we use numerical simulations of groove terrain formation to develop a strain history for Ganymede that is generally consistent at local, regional, and global scales. These simulations reproduce groove-like amplitudes, wavelengths, and average slopes at modest regional extensions (10-15%). The modest strains are more consistent with global constraints on Ganymede's expansion. Yet locally, we also find that surface strains can be much larger (30-60%) in the same simulations, consistent with observations of highly-extended impact craters. Thus our simulations satisfy both the smallest-scale and largest-scale inferences of strain on Ganymede. The growth rate of the topography is consistent with (or exceeds) predictions of analytical models, and results from the use of a non-associated plastic rheology that naturally permits localization of brittle failure (plastic strain) into linear fault-like shear zones. These fault-like zones are organized into periodically-spaced graben-like structures with stepped, steeply-dipping faults. As in previous work, groove amplitudes and wavelengths depend on both the imposed heat flux and surface temperature, but because our brittle strength increases with depth, we find (for the parameters explored) that the growth rate of topography is initially faster for lower heat flows. We observe a transition to narrow rifting for higher heat flows and larger strains, which is a potential pathway for breakaway margin or band formation.

Dynamic strains for earthquake source characterization

USGS Publications Warehouse

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.

Feasibility and reproducibility of feature-tracking-based strain and strain rate measures of the left ventricle in different diseases and genders.

PubMed

Maceira, Alicia M; Tuset-Sanchis, Luis; López-Garrido, Miguel; San Andres, Marta; López-Lereu, M Pilar; Monmeneu, Jose V; García-González, M Pilar; Higueras, Laura

2018-05-01

The measurement of myocardial deformation by strain analysis is an evolving tool to quantify regional and global myocardial function. To assess the feasibility and reproducibility of myocardial strain/strain rate measurements with magnetic resonance feature tracking (MR-FT) in healthy subjects and in patient groups. Prospective study. Sixty patients (20 hypertensives with left ventricular (LV) hypertrophy (H); 20 nonischemic dilated cardiomyopathy (D); 20 ischemic heart disease (I); as well as 20 controls (C) were included, 10 men and 10 women in each group. A 1.5T MR protocol including steady-state free precession (SSFP) cine sequences in the standard views and late enhancement sequences. LV volumes, mass, global and regional radial, circumferential, and longitudinal strain/strain rate were measured using CVI42 software. The analysis time was recorded. Intraobserver and interobserver agreement and intraclass correlation coefficients (ICC) were obtained for reproducibility assessment as well as differences according to gender and group of pertinence. Strain/strain rate analysis could be achieved in all subjects. The average analysis time was 14 ± 3 minutes. The average intraobserver ICC was excellent (ICC >0.90) for strain and good (ICC >0.75) for strain rate. Reproducibility of strain measurements was good to excellent (ICC >0.75) for all groups of subjects and both genders. Reproducibility of strain measurements was good for basal segments (ICC >0.75) and excellent for middle and apical segments (ICC >0.90). Reproducibility of strain rate measurements was moderate for basal segments (ICC >0.50) and good for middle and apical segments. MR-FT for strain/strain rate analysis is a feasible and highly reproducible technique. CVI42 FT analysis was equally feasible and reproducible in various pathologies and between genders. Better reproducibility was seen globally for middle and apical segments, which needs further clarification. 3 Technical Efficacy Stage 2 J

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

ERIC Educational Resources Information Center

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…

Genome analysis of Mycoplasma synoviae strain MS-H, the most common M. synoviae strain with a worldwide distribution.

PubMed

Zhu, Ling; Shahid, Muhammad A; Markham, John; Browning, Glenn F; Noormohammadi, Amir H; Marenda, Marc S

2018-02-02

The bacterial pathogen Mycoplasma synoviae can cause subclinical respiratory disease, synovitis, airsacculitis and reproductive tract disease in poultry and is a major cause of economic loss worldwide. The M. synoviae strain MS-H was developed by chemical mutagenesis of an Australian isolate and has been used as a live attenuated vaccine in many countries over the past two decades. As a result it may now be the most prevalent strain of M. synoviae globally. Differentiation of the MS-H vaccine from local field strains is important for epidemiological investigations and is often required for registration of the vaccine. The complete genomic sequence of the MS-H strain was determined using a combination of Illumina and Nanopore methods and compared to WVU-1853, the M. synoviae type strain isolated in the USA 30 years before the parent strain of MS-H, and MS53, a more recent isolate from Brazil. The vaccine strain genome had a slightly larger number of pseudogenes than the two other strains and contained a unique 55 kb chromosomal inversion partially affecting a putative genomic island. Variations in gene content were also noted, including a deoxyribose-phosphate aldolase (deoC) fragment and an ATP-dependent DNA helicase gene found only in MS-H. Some of these sequences may have been acquired horizontally from other avian mycoplasma species. MS-H was somewhat more similar to WVU-1853 than to MS53. The genome sequence of MS-H will enable identification of vaccine-specific genetic markers for use as diagnostic and epidemiological tools to better control M. synoviae.

Curvature reduces bending strains in the quokka femur

PubMed Central

McCabe, Kyle; Henderson, Keith; Pantinople, Jess; Milne, Nick

2017-01-01

This study explores how curvature in the quokka femur may help to reduce bending strain during locomotion. The quokka is a small wallaby, but the curvature of the femur and the muscles active during stance phase are similar to most quadrupedal mammals. Our hypothesis is that the action of hip extensor and ankle plantarflexor muscles during stance phase place cranial bending strains that act to reduce the caudal curvature of the femur. Knee extensors and biarticular muscles that span the femur longitudinally create caudal bending strains in the caudally curved (concave caudal side) bone. These opposing strains can balance each other and result in less strain on the bone. We test this idea by comparing the performance of a normally curved finite element model of the quokka femur to a digitally straightened version of the same bone. The normally curved model is indeed less strained than the straightened version. To further examine the relationship between curvature and the strains in the femoral models, we also tested an extra-curved and a reverse-curved version with the same loads. There appears to be a linear relationship between the curvature and the strains experienced by the models. These results demonstrate that longitudinal curvature in bones may be a manipulable mechanism whereby bone can induce a strain gradient to oppose strains induced by habitual loading. PMID:28348929

Occupational stress and strain in the Royal Navy 2007.

PubMed

Bridger, R S; Brasher, K; Dew, A; Kilminster, S

2008-12-01

Previous surveys of psychological strain in the Naval Service (NS) have shown higher than expected levels of strain when compared to the general population. To repeat the survey last carried out in 2004 and to obtain further information on the nature of the occupational stressors associated with strain. General Health Questionnaire-12 strain rates and job/life stressors were measured using a Work and Well-Being Questionnaire. Models of strain were developed for male and female personnel in the Royal Navy (RN) and males in the Royal Marines (RM). The response rate was 57%. The psychological strain rate was 31.5% overall. Personnel suffering from strain tended to be 'overcommitted' to work, had low levels of commitment to the NS and had suffered stressful life events (SLEs) in the previous 12 months. Strain rates declined with age and rank in males, but not in females. Strain was significantly positively correlated with levels of overcommitment, effort-reward imbalance (ERI), role conflict, work-family conflict, organizational commitment and exposure to SLEs. Models of strain in the males and females in the RN and in the RM accounted for between 37 and 44% of the variance in strain. The survey provides evidence for both the demand control and ERI models-components of these models contribute independently to strain. High levels of commitment to the organization were associated with lower strain and exposure to SLEs to higher strain.

Tensile stress-strain behavior of boron/aluminum laminates

NASA Technical Reports Server (NTRS)

Sova, J. A.; Poe, C. C., Jr.

1978-01-01

The tensile stress-strain behavior of five types of boron/aluminum laminates was investigated. Longitudinal and transverse stress-strain curves were obtained for monotonic loading to failure and for three cycles of loading to successively higher load levels. The laminate strengths predicted by assuming that the zero deg plies failed first correlated well with the experimental results. The stress-strain curves for all the boron/aluminum laminates were nonlinear except at very small strains. Within the small linear regions, elastic constants calculated from laminate theory corresponded to those obtained experimentally to within 10 to 20 percent. A limited amount of cyclic loading did not affect the ultimate strength and strain for the boron/aluminum laminates. The laminates, however, exhibited a permanent strain on unloading. The Ramberg-Osgood equation was fitted to the stress-strain curves to obtain average curves for the various laminates.

Lattice Strain Due to an Atomic Vacancy

PubMed Central

Li, Shidong; Sellers, Michael S.; Basaran, Cemal; Schultz, Andrew J.; Kofke, David A.

2009-01-01

Volumetric strain can be divided into two parts: strain due to bond distance change and strain due to vacancy sources and sinks. In this paper, efforts are focused on studying the atomic lattice strain due to a vacancy in an FCC metal lattice with molecular dynamics simulation (MDS). The result has been compared with that from a continuum mechanics method. It is shown that using a continuum mechanics approach yields constitutive results similar to the ones obtained based purely on molecular dynamics considerations. PMID:19582230

Using strain rates to forecast seismic hazards

USGS Publications Warehouse

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.

Strain isolated ceramic coatings

NASA Technical Reports Server (NTRS)

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

1985-01-01

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

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

PubMed

Roos, Viktoria; Ulett, Glen C; Schembri, Mark A; Klemm, Per

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 urine and show that it can outcompete a representative spectrum of UPEC strains for growth in urine. The unique ability of ABU E. coli 83972 to outcompete UPEC in urine was also demonstrated in a murine model of human UTI, confirming the selective advantage over UPEC in vivo. Comparison of global gene expression profiles of E. coli 83972 grown in lab medium and human urine revealed significant differences in expression levels in the two media; significant down-regulation of genes encoding virulence factors such as hemolysin, lipid A, and capsular polysaccharides was observed in cells grown in urine. Clearly, divergent abilities of ABU E. coli and UPEC to exploit human urine as a niche for persistence and survival suggest that these key differences may be exploited for preventative and/or therapeutic approaches.

Strain-based HLA association analysis identified HLA-DRB1*09:01 associated with modern strain tuberculosis.

PubMed

Toyo-Oka, L; Mahasirimongkol, S; Yanai, H; Mushiroda, T; Wattanapokayakit, S; Wichukchinda, N; Yamada, N; Smittipat, N; Juthayothin, T; Palittapongarnpim, P; Nedsuwan, S; Kantipong, P; Takahashi, A; Kubo, M; Sawanpanyalert, P; Tokunaga, K

2017-09-01

Tuberculosis (TB) occurs as a result of complex interactions between the host immune system and pathogen virulence factors. Human leukocyte antigen (HLA) class II molecules play an important role in the host immune system. However, no study has assessed the association between HLA class II genes and susceptibility to TB caused by specific strains. This study investigated the possible association of HLA class II genes with TB caused by modern and ancient Mycobacterium tuberculosis (MTB). The study included 682 patients with TB and 836 control subjects who were typed for HLA-DRB1 and HLA-DQB1 alleles. MTB strains were classified using a large sequence polymorphism typing method. Association analysis was performed using common HLA alleles and haplotypes in different MTB strains. HLA association analysis of patients infected with modern MTB strains showed significant association for HLA-DRB1*09:01 (odds ratio [OR] = 1.82; P-value = 9.88 × 10 -4 ) and HLA-DQB1*03:03 alleles (OR = 1.76; P-value = 1.31 × 10 -3 ) with susceptibility to TB. Haplotype analysis confirmed that these alleles were in strong linkage disequilibrium and did not exert an interactive effect. Thus, the results of this study showed an association between HLA class II genes and susceptibility to TB caused by modern MTB strains, suggesting the importance of strain-specific analysis to determine susceptibility genes associated with TB. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

[Screening and optimization of cholesterol conversion strain].

PubMed

Fan, Dan; Xiong, Bingjian; Pang, Cuiping; Zhu, Xiangdong

2014-10-04

Bacterial strain SE-1 capable of transforming cholesterol was isolated from soil and characterized. The transformation products were identified. Fermentation conditions were optimized for conversion. Cholesterol was used as sole carbon source to isolate strain SE-1. Morphology, physiological and biochemical characteristics of strain SE-1 were studied. 16S rRNA gene was sequenced and subjected to phylogenetic analysis. Fermentation supernatants were extracted with chloroform, the transformation products were analyzed by silica gel thin layer chromatography and Sephadex LH20. Their structures were identified by 1H-NMR and 13C-NMR. Fermentation medium including carbon and nitrogen, methods of adding substrates and fermentation conditions for Strain SE-1 were optimized. Strain SE-1 was a Gram-negative bacterium, exhibiting the highest homologs to Burkholderia cepacia based on the physiological analysis. The sequence analysis of 16S rRNA gene of SE-1 strain and comparison with related Burkholderia show that SE-1 strain was very close to B. cepacia (Genbank No. U96927). The similarity was 99%. The result of silica gel thin layer chromatography shows that strain SE-1 transformed cholesterol to two products, 7beta-hydroxycholesterol and the minor product was 7-oxocholesterol. The optimum culture conditions were: molasses 5%, (NH4 )2SO4 0.3%, 4% of inoculation, pH 7.5 and 36 degrees C. Under the optimum culture condition, the conversion rate reached 34.4% when concentration of cholesterol-Tween 80 was 1 g/L. Cholesterol 7beta-hydroxylation conversion rate under optimal conditions was improved by 20.8%. Strain SE-1 isolated from soil is capable of converting cholesterol at lab-scale.

High-Temperature Resistance Strain Gauges

NASA Technical Reports Server (NTRS)

Lei, Jih-Fen

1994-01-01

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

Moire strain analysis of paper

Treesearch

R. E. Rowlands; P. K. Beasley; D. E. Gunderson

1983-01-01

Efficient use of paper products involves using modern aspects of materials science and engineering mechanics. This implies the ability to determine simultaneously different components of strain at multiple locations and under static or dynamic conditions. Although measuring strains in paper has been a topic of interest for over 40 years, present capability remains...

Strain Rate Sensitivity of Graphite/Polymer Laminate Composites

NASA Astrophysics Data System (ADS)

Syed, Izhar H.; Brar, N. S.

2002-07-01

Strain rate sensitivities of Graphite/Epoxy and Graphite/Peek laminate composites are investigated by measuring their stress-strain response at strain rates of 0.001/s, 0.1/s, and 400/s. Tension specimens of the composite laminates are fabricated in a dog-bone shape. Stress-strain data at quasi-static rates of 0.001/s and 0.1/s are obtained using a servohydraulic test system. High strain rate data are produced with a Direct Tension Split Hopkinson Bar (DTSHB). A tensile stress pulse is generated in the DTSHB by impacting a stopper flange at the end of the incident bar with an aluminum/polymeric tube launched around the incident bar. The failure (flow) tensile stress of Graphite/Epoxy increases from 240 MPa to 280±10 MPa (ɛ = 0.06) when the strain rate is raised from 0.001/s to 400/s. For Graphite/Peek, failure (flow) tension stress increases from 175 MPa at a strain rate of 0.001/s to 270±20 MPa at a strain rate of 400/s.

Development of High Cordycepin-Producing Cordyceps militaris Strains.

PubMed

Kang, Naru; Lee, Hyun-Hee; Park, Inmyoung; Seo, Young-Su

2017-03-01

Cordyceps militaris , known as Dong-Chong-Xia-Cao, produces the most cordycepin among Cordyceps species and can be cultured artificially. For these reasons, C. militaris is widely used as herb or functional food in the East Asia. In this study, we developed a new strain of C. militaris that produces higher cordycepin content than parent strains through mating-based sexual reproduction. Twenty parent strains were collected and identified as C. militaris based on internal trasncrived spacer and rDNA sequences. Seven single spores of MAT 1-1 idiomorph and five single spores of MAT 1-2 idiomorph were isolated from 12 parent strains. When 35 combinations were mated on the brown rice medium with the isolated single spores, eight combinations formed a stroma with a normal perithecia and confirmed mated strains. High pressure liquid chromatography analysis showed that mated strain KSP8 produced the most cordycepin in all the media among all the tested strains. This result showed due to genetic recombination occurring during the sexual reproduction of C. militaris . The development of C. militaris strain with increased cordycepin content by this approach can help not only to generate new C. militaris strains, but also to contribute to the health food or medicine industry.

Development of High Cordycepin-Producing Cordyceps militaris Strains

PubMed Central

Kang, Naru; Lee, Hyun-Hee; Park, Inmyoung

2017-01-01

Cordyceps militaris, known as Dong-Chong-Xia-Cao, produces the most cordycepin among Cordyceps species and can be cultured artificially. For these reasons, C. militaris is widely used as herb or functional food in the East Asia. In this study, we developed a new strain of C. militaris that produces higher cordycepin content than parent strains through mating-based sexual reproduction. Twenty parent strains were collected and identified as C. militaris based on internal trasncrived spacer and rDNA sequences. Seven single spores of MAT 1-1 idiomorph and five single spores of MAT 1-2 idiomorph were isolated from 12 parent strains. When 35 combinations were mated on the brown rice medium with the isolated single spores, eight combinations formed a stroma with a normal perithecia and confirmed mated strains. High pressure liquid chromatography analysis showed that mated strain KSP8 produced the most cordycepin in all the media among all the tested strains. This result showed due to genetic recombination occurring during the sexual reproduction of C. militaris. The development of C. militaris strain with increased cordycepin content by this approach can help not only to generate new C. militaris strains, but also to contribute to the health food or medicine industry. PMID:28435352

Acceleration and Velocity Sensing from Measured Strain

NASA Technical Reports Server (NTRS)

Pak, Chan-Gi; Truax, Roger

2016-01-01

A simple approach for computing acceleration and velocity of a structure from the strain is proposed in this study. First, deflection and slope of the structure are computed from the strain using a two-step theory. Frequencies of the structure are computed from the time histories of strain using a parameter estimation technique together with an Autoregressive Moving Average model. From deflection, slope, and frequencies of the structure, acceleration and velocity of the structure can be obtained using the proposed approach. shape sensing, fiber optic strain sensor, system equivalent reduction and expansion process.

Inflatable device for installing strain gage bridges

NASA Technical Reports Server (NTRS)

Cook, C. E.; Smith, G. E.; Monaghan, R. C. (Inventor)

1983-01-01

Methods and devices for installing in a tubular shaft multiple strain gages are disclosed with focus on a method and a device for pneumatically forcing strain gages into seated engagement with the internal surfaces of a tubular shaft in an installation of multiple strain gages in a tubular shaft. The strain gages or other electron devices are seated in a template-like component which is wrapped about a pneumatically expansible body. The component is inserted into a shaft and the body is pneumatically expanded after a suitable adhesive was applied to the surfaces.

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

ERIC Educational Resources Information Center

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,…

Complete Genome Sequence of Pigmentation Negative Yersinia Pestis strain Cadman Running head: Complete Genome Sequence of Y. pestis strain Cadman

DTIC Science & Technology

2016-10-27

Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland, USA 9 10 11 Running head: Complete Genome Sequence of Y. pestis strain Cadman...1 Complete Genome Sequence of Pigmentation Negative Yersinia pestis strain Cadman 1 2 3 Sean Lovetta, Kitty Chaseb, Galina Korolevaa, Gustavo...we report the genome sequence of Yersinia pestis strain Cadman, an attenuated strain 25 lacking the pgm locus. Y. pestis is the causative agent of

Management of digital eye strain.

PubMed

Coles-Brennan, Chantal; Sulley, Anna; Young, Graeme

2018-05-23

Digital eye strain, an emerging public health issue, is a condition characterised by visual disturbance and/or ocular discomfort related to the use of digital devices and resulting from a range of stresses on the ocular environment. This review aims to provide an overview of the extensive literature on digital eye strain research with particular reference to the clinical management of symptoms. As many as 90 per cent of digital device users experience symptoms of digital eye strain. Many studies suggest that the following factors are associated with digital eye strain: uncorrected refractive error (including presbyopia), accommodative and vergence anomalies, altered blinking pattern (reduced rate and incomplete blinking), excessive exposure to intense light, closer working distance, and smaller font size. Since a symptom may be caused by one or more factors, a holistic approach should be adopted. The following management strategies have been suggested: (i) appropriate correction of refractive error, including astigmatism and presbyopia; (ii) management of vergence anomalies, with the aim of inducing or leaving a small amount of heterophoria (~1.5 Δ Exo); (iii) blinking exercise/training to maintain normal blinking pattern; (iv) use of lubricating eye drops (artificial tears) to help alleviate dry eye-related symptoms; (v) contact lenses with enhanced comfort, particularly at end-of-day and in challenging environments; (vi) prescription of colour filters in all vision correction options, especially blue light-absorbing filters; and (vii) management of accommodative anomalies. Prevention is the main strategy for management of digital eye strain, which involves: (i) ensuring an ergonomic work environment and practice (through patient education and the implementation of ergonomic workplace policies); and (ii) visual examination and eye care to treat visual disorders. Special consideration is needed for people at a high risk of digital eye strain, such as computer

Fiber-Optic Strain Gauge With High Resolution And Update Rate

NASA Technical Reports Server (NTRS)

Figueroa, Fernando; Mahajan, Ajay; Sayeh, Mohammad; Regez, Bradley

2007-01-01

An improved fiber-optic strain gauge is capable of measuring strains in the approximate range of 0 to 50 microstrains with a resolution of 0.1 microstrain. (To some extent, the resolution of the strain gauge can be tailored and may be extensible to 0.01 microstrain.) The total cost of the hardware components of this strain gauge is less than $100 at 2006 prices. In comparison with prior strain gauges capable of measurement of such low strains, this strain gauge is more accurate, more economical, and more robust, and it operates at a higher update rate. Strain gauges like this one are useful mainly for measuring small strains (including those associated with vibrations) in such structures as rocket test stands, buildings, oilrigs, bridges, and dams. The technology was inspired by the need to measure very small strains on structures supporting liquid oxygen tanks, as a way to measure accurately mass of liquid oxygen during rocket engine testing. This improved fiber-optic strain gauge was developed to overcome some of the deficiencies of both traditional foil strain gauges and prior fiber-optic strain gauges. Traditional foil strain gages do not have adequate signal-to-noise ratios at such small strains. Fiber-optic strain gauges have been shown to be potentially useful for measuring such small strains, but heretofore, the use of fiberoptic strain gauges has been inhibited, variously, by complexity, cost, or low update rate.

Proof that Burkholderia Strains Form Effective Symbioses with Legumes: a Study of Novel Mimosa-Nodulating Strains from South America

PubMed Central

Chen, Wen-Ming; de Faria, Sergio M.; Straliotto, Rosângela; Pitard, Rosa M.; Simões-Araùjo, Jean L.; Chou, Jui-Hsing; Chou, Yi-Ju; Barrios, Edmundo; Prescott, Alan R.; Elliott, Geoffrey N.; Sprent, Janet I.; Young, J. Peter W.; James, Euan K.

2005-01-01

Twenty Mimosa-nodulating bacterial strains from Brazil and Venezuela, together with eight reference Mimosa-nodulating rhizobial strains and two other β-rhizobial strains, were examined by amplified rRNA gene restriction analysis. They fell into 16 patterns and formed a single cluster together with the known β-rhizobia, Burkholderia caribensis, Burkholderia phymatum, and Burkholderia tuberum. The 16S rRNA gene sequences of 15 of the 20 strains were determined, and all were shown to belong to the genus Burkholderia; four distinct clusters could be discerned, with strains isolated from the same host species usually clustering very closely. Five of the strains (MAP3-5, Br3407, Br3454, Br3461, and Br3469) were selected for further studies of the symbiosis-related genes nodA, the NodD-dependent regulatory consensus sequences (nod box), and nifH. The nodA and nifH sequences were very close to each other and to those of B. phymatum STM815, B. caribensis TJ182, and Cupriavidus taiwanensis LMG19424 but were relatively distant from those of B. tuberum STM678. In addition to nodulating their original hosts, all five strains could also nodulate other Mimosa spp., and all produced nodules on Mimosa pudica that had nitrogenase (acetylene reduction) activities and structures typical of effective N2-fixing symbioses. Finally, both wild-type and green fluorescent protein-expressing transconjugant strains of Br3461 and MAP3-5 produced N2-fixing nodules on their original hosts, Mimosa bimucronata (Br3461) and Mimosa pigra (MAP3-5), and hence this confirms strongly that Burkholderia strains can form effective symbioses with legumes. PMID:16269788

Proof that Burkholderia strains form effective symbioses with legumes: a study of novel Mimosa-nodulating strains from South America.

PubMed

Chen, Wen-Ming; de Faria, Sergio M; Straliotto, Rosângela; Pitard, Rosa M; Simões-Araùjo, Jean L; Chou, Jui-Hsing; Chou, Yi-Ju; Barrios, Edmundo; Prescott, Alan R; Elliott, Geoffrey N; Sprent, Janet I; Young, J Peter W; James, Euan K

2005-11-01

Twenty Mimosa-nodulating bacterial strains from Brazil and Venezuela, together with eight reference Mimosa-nodulating rhizobial strains and two other beta-rhizobial strains, were examined by amplified rRNA gene restriction analysis. They fell into 16 patterns and formed a single cluster together with the known beta-rhizobia, Burkholderia caribensis, Burkholderia phymatum, and Burkholderia tuberum. The 16S rRNA gene sequences of 15 of the 20 strains were determined, and all were shown to belong to the genus Burkholderia; four distinct clusters could be discerned, with strains isolated from the same host species usually clustering very closely. Five of the strains (MAP3-5, Br3407, Br3454, Br3461, and Br3469) were selected for further studies of the symbiosis-related genes nodA, the NodD-dependent regulatory consensus sequences (nod box), and nifH. The nodA and nifH sequences were very close to each other and to those of B. phymatum STM815, B. caribensis TJ182, and Cupriavidus taiwanensis LMG19424 but were relatively distant from those of B. tuberum STM678. In addition to nodulating their original hosts, all five strains could also nodulate other Mimosa spp., and all produced nodules on Mimosa pudica that had nitrogenase (acetylene reduction) activities and structures typical of effective N2-fixing symbioses. Finally, both wild-type and green fluorescent protein-expressing transconjugant strains of Br3461 and MAP3-5 produced N2-fixing nodules on their original hosts, Mimosa bimucronata (Br3461) and Mimosa pigra (MAP3-5), and hence this confirms strongly that Burkholderia strains can form effective symbioses with legumes.

Piezoelectric effect in non-uniform strained carbon nanotubes

NASA Astrophysics Data System (ADS)

Ilina, M. V.; Blinov, Yu F.; Ilin, O. I.; Rudyk, N. N.; Ageev, O. A.

2017-10-01

The piezoelectric effect in non-uniform strained carbon nanotubes (CNTs) has been studied. It is shown that the magnitude of strained CNTs surface potential depends on a strain value. It is established that the resistance of CNT also depends on the strain and internal electric field, which leads to the hysteresis in the current-voltage characteristics. Analysis of experimental studies of the non-uniform strained CNT with a diameter of 92 nm and a height of 2.1 μm allowed us to estimate the piezoelectric coefficient 0.107 ± 0.032 C/m2.

Influences of misfit strains on liquid phase heteroepitaxial growth

NASA Astrophysics Data System (ADS)

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.

Nonspecific Bacterial Flora Isolated from the Body Surface and Inside Ixodes ricinus Ticks.

PubMed

Okła, Hubert; Sosnowska, Malwina; Jasik, Krzysztof P; Słodki, Jan; Wojtyczka, Robert D

2012-09-28

Ixodes ricinus and other representatives of the order Ixodida are vectors of typical pathogens: Borrelia burgdorferi sensu lato, Anaplasma phagocytophilium, Babesia spp., a tick-borne encephalitis virus, and other microorganisms which are important from a medical and veterinary point of view. The presented study focuses on the verification of nonspecific bacterial flora of I. ricinus. We analyzed ticks collected in a forest region in Silesia, an industrial district in Poland. Methods of classical microbiology and biochemical assays (API 20 NE test, API Staph test and MICRONAUT System) were used for isolation and identification of microorganisms living on the body surface of I. ricinus and inside ticks. The results show the presence of various bacteria on the surface and inside ticks' bodies. During the study, we isolated Acinetobacter lwoffi, Pseudomonas fluorescens, Aeromonas hydrophila, Achromobacter denitrificans, Alcaligenes faecalis, Stenotrophomonas maltophilia, Pseudomonas oryzihabitans, Micrococcus spp., Kocuria varians, Staphylococcus lentus, Kocuria kristinae, Streptococcus pneumoniae, Rhizobium radiobacter, Staphylococcus xylosus. Majority of the isolated species are non-pathogenic environmental microorganisms, but some of the isolated bacterial strains could cause severe infections.

Phylogenetic relationship of Ornithobacterium rhinotracheale strains.

PubMed

DE Oca-Jimenez, Roberto Montes; Vega-Sanchez, Vicente; Morales-Erasto, Vladimir; Salgado-Miranda, Celene; Blackall, Patrick J; Soriano-Vargas, Edgardo

2018-04-10

The bacterium Ornithobacterium rhinotracheale is associated with respiratory disease in wild birds and poultry. In this study, the phylogenetic analysis of nine reference strains of O. rhinotracheale belonging to serovars A to I, and eight Mexican isolates belonging to serovar A, was performed. The analysis was extended to include available sequences from another 23 strains available in the public domain. The analysis showed that the 40 sequences formed six clusters, I to VI. All eight Mexican field isolates were placed in cluster I. One of the reference strains appears to present genetic diversity not previously recognized and was placed in a new genetic cluster. In conclusion, the phylogenetic analysis of O. rhinotracheale strains, based on the 16S rRNA gene, is a suitable tool for epidemiologic studies.

Hospital strain colonization by Staphylococcus epidermidis.

PubMed

Blum-Menezes, D; Bratfich, O J; Padoveze, M C; Moretti, M L

2009-03-01

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.

Simultaneous narrowband ultrasonic strain-flow imaging

NASA Astrophysics Data System (ADS)

Tsou, Jean K.; Mai, Jerome J.; Lupotti, Fermin A.; Insana, Michael F.

2004-04-01

We are summarizing new research aimed at forming spatially and temporally registered combinations of strain and color-flow images using echo data recorded from a commercial ultrasound system. Applications include diagnosis of vascular diseases and tumor malignancies. The challenge is to meet the diverse needs of each measurement. The approach is to first apply eigenfilters that separate echo components from moving tissues and blood flow, and then estimate blood velocity and tissue displacement from the filtered-IQ-signal phase modulations. At the cost of a lower acquisition frame rate, we find the autocorrelation strain estimator yields higher resolution strain estimate than the cross-correlator since estimates are made from ensembles at a single point in space. The technique is applied to in vivo carotid imaging, to demonstrate the sensitivity for strain-flow vascular imaging.

Complete Genome Sequences of Lactobacillus johnsonii Strain N6.2 and Lactobacillus reuteri Strain TD1.

PubMed

Leonard, Michael T; Valladares, Ricardo B; Ardissone, Alexandria; Gonzalez, Claudio F; Lorca, Graciela L; Triplett, Eric W

2014-05-08

We report here the complete genome sequences of Lactobacillus johnsonii strain N6.2, a homofermentative lactic acid intestinal bacterium, and Lactobacillus reuteri strain TD1, a heterofermentative lactic acid intestinal bacterium, both isolated from a type 1 diabetes-resistant rat model.

Tensile stress-strain behavior of graphite/epoxy laminates

NASA Technical Reports Server (NTRS)

Garber, D. P.

1982-01-01

The tensile stress-strain behavior of a variety of graphite/epoxy laminates was examined. Longitudinal and transverse specimens from eleven different layups were monotonically loaded in tension to failure. Ultimate strength, ultimate strain, and strss-strain curves wee obtained from four replicate tests in each case. Polynominal equations were fitted by the method of least squares to the stress-strain data to determine average curves. Values of Young's modulus and Poisson's ratio, derived from polynomial coefficients, were compared with laminate analysis results. While the polynomials appeared to accurately fit the stress-strain data in most cases, the use of polynomial coefficients to calculate elastic moduli appeared to be of questionable value in cases involving sharp changes in the slope of the stress-strain data or extensive scatter.

Strain-mediated mechanical coupling to diamond spins

NASA Astrophysics Data System (ADS)

Bleszynski Jayich, Ania

2015-03-01

Nitrogen-vacancy (NV) centers in diamond are atomic-scale spin systems with remarkable quantum properties that persist to room temperature. The recent demonstration of high-quality single-crystal diamond resonators has led to significant interest in a hybrid system consisting of NV spins that interact with the resonant phonon modes of a macroscopic mechanical resonator through crystal strain. We demonstrate dynamic, strain-mediated coupling of the mechanical motion of a diamond cantilever to the spin of an embedded NV. Via quantum control of the spin, we quantitatively characterize the axial and transverse strain sensitivities of the nitrogen-vacancy ground-state spin. The nitrogen-vacancy center is an atomic scale sensor and we demonstrate spin-based strain imaging with a strain sensitivity of 3x10-6 strain Hz1/2. We discuss prospects for reaching the regime of quantum coupling between phonons and spins, and we present our results in this direction. This hybrid system has exciting prospects for a phonon-based approach to integrating NVs into quantum networks. Funding from the AFOSR MURI and NSF CAREER programs are gratefully acknowledged.

Species-specific identification of commercial probiotic strains.

PubMed

Yeung, P S M; Sanders, M E; Kitts, C L; Cano, R; Tong, P S

2002-05-01

Products containing probiotic bacteria are gaining popularity, increasing the importance of their accurate speciation. Unfortunately, studies have suggested that improper labeling of probiotic species is common in commercial products. Species identification of a bank of commercial probiotic strains was attempted using partial 16S rDNA sequencing, carbohydrate fermentation analysis, and cellular fatty acid methyl ester analysis. Results from partial 16S rDNA sequencing indicated discrepancies between species designations for 26 out of 58 strains tested, including two ATCC Lactobacillus strains. When considering only the commercial strains obtained directly from the manufacturers, 14 of 29 strains carried species designations different from those obtained by partial 16S rDNA sequencing. Strains from six commercial products were species not listed on the label. The discrepancies mainly occurred in Lactobacillus acidophilus and Lactobacillus casei groups. Carbohydrate fermentation analysis was not sensitive enough to identify species within the L. acidophilus group. Fatty acid methyl ester analysis was found to be variable and inaccurate and is not recommended to identify probiotic lactobacilli.

Apparent-Strain Correction for Combined Thermal and Mechanical Testing

NASA Technical Reports Server (NTRS)

Johnson, Theodore F.; O'Neil, Teresa L.

2007-01-01

Combined thermal and mechanical testing requires that the total strain be corrected for the coefficient of thermal expansion mismatch between the strain gage and the specimen or apparent strain when the temperature varies while a mechanical load is being applied. Collecting data for an apparent strain test becomes problematic as the specimen size increases. If the test specimen cannot be placed in a variable temperature test chamber to generate apparent strain data with no mechanical loads, coupons can be used to generate the required data. The coupons, however, must have the same strain gage type, coefficient of thermal expansion, and constraints as the specimen to be useful. Obtaining apparent-strain data at temperatures lower than -320 F is challenging due to the difficulty to maintain steady-state and uniform temperatures on a given specimen. Equations to correct for apparent strain in a real-time fashion and data from apparent-strain tests for composite and metallic specimens over a temperature range from -450 F to +250 F are presented in this paper. Three approaches to extrapolate apparent-strain data from -320 F to -430 F are presented and compared to the measured apparent-strain data. The first two approaches use a subset of the apparent-strain curves between -320 F and 100 F to extrapolate to -430 F, while the third approach extrapolates the apparent-strain curve over the temperature range of -320 F to +250 F to -430 F. The first two approaches are superior to the third approach but the use of either of the first two approaches is contingent upon the degree of non-linearity of the apparent-strain curve.

Strain superlattices in graphene

NASA Astrophysics Data System (ADS)

Zhang, Yingjie; Kim, Youngseok; Lyding, Joseph; Gilbert, Matthew; Mason, Nadya

Superlattices have been widely explored to tailor the electronic properties of two-dimensional electron systems. Previous approaches to create superlattices have been limited to periodic potential modulations, either in the form of electrostatic gating or moiré heterostructures. Here we present a new strategy to generate superlattices in 2D materials. We deposit these 2D membranes on a periodic array of dielectric nanospheres, and achieve superlattices with periodic strain modulations. We studied the electronic and magneto-transport properties of strained graphene superlattices, and observed salient features of Dirac point cloning and Hofstadter's butterfly. Furthermore, we were able to tune the transport properties by changing the magnitude of strain in the graphene superlattice. This new degree of freedom provides a novel platform both for fundamental studies of 2D electron correlations and for prospective applications in 2D electronic devices. Y.Z. and N.M. acknowledge support from the National Science Foundation under Grant No. ENG-1434147.

Strain-Detecting Composite Materials

NASA Technical Reports Server (NTRS)

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

2016-01-01

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

A novel HRM assay for differentiating classical strains and highly pathogenic strains of type 2 porcine reproductive and respiratory syndrome virus.

PubMed

Sun, Junying; Bingga, Gali; Liu, Zhicheng; Zhang, Chunhong; Shen, Haiyan; Guo, Pengju; Zhang, Jianfeng

2018-06-01

Differentiation of classical strains and highly pathogenic strains of porcine reproductive and respiratory syndrome virus is crucial for effective vaccination programs and epidemiological studies. We used nested PCR and high resolution melting curve analysis with unlabeled probe to distinguish between the classical and the highly pathogenic strains of this virus. Two sets of primers and a 20 bp unlabeled probe were designed from the NSP3 gene. The unlabeled probe included two mutations specific for the classical and highly pathogenic strains of the virus. An additional primer set from the NSP2 gene of the highly pathogenic vaccine strain JXA1-R was used to detect its exclusive single nucleotide polymorphism. We tested 107 clinical samples, 21 clinical samples were positive for PRRSV (consistent with conventional PCR assay), among them four were positive for the classical strain with the remainder 17 for the highly pathogenic strain. Around 10 °C difference between probe melting temperatures showed the high discriminatory power of this method. Among highly pathogenic positive samples, three samples were determined as positive for JXA1-R vaccine-related strain with a 95% genotype confidence percentage. All these genotyping results using the high resolution melting curve assay were confirmed with DNA sequencing. This unlabeled probe method provides an alternative means to differentiate the classical strains from the highly pathogenic porcine reproductive and respiratory syndrome virus strains rapidly and accurately. Copyright © 2018. Published by Elsevier Ltd.

Shear, principal, and equivalent strains in equal-channel angular deformation

NASA Astrophysics Data System (ADS)

Xia, K.; Wang, J.

2001-10-01

The shear and principal strains involved in equal channel angular deformation (ECAD) were analyzed using a variety of methods. A general expression for the total shear strain calculated by integrating infinitesimal strain increments gave the same result as that from simple geometric considerations. The magnitude and direction of the accumulated principal strains were calculated based on a geometric and a matrix algebra method, respectively. For an intersecting angle of π/2, the maximum normal strain is 0.881 in the direction at π/8 (22.5 deg) from the longitudinal direction of the material in the exit channel. The direction of the maximum principal strain should be used as the direction of grain elongation. Since the principal direction of strain rotates during ECAD, the total shear strain and principal strains so calculated do not have the same meaning as those in a strain tensor. Consequently, the “equivalent” strain based on the second invariant of a strain tensor is no longer an invariant. Indeed, the equivalent strains calculated using the total shear strain and that using the total principal strains differed as the intensity of deformation increased. The method based on matrix algebra is potentially useful in mathematical analysis and computer calculation of ECAD.

[Enhancement of laccase activity by combining white rot fungal strains].

PubMed

He, Rong-yu; Liu, Xiao-feng; Yan, Zhi-ying; Yuan, Yue-xiang; Liao, Yin-zhang; Li, Xu-dong

2010-02-01

The method of combining white rot fungal strains was used to enhance laccase activity, and the interaction mechanism between strains was also studied. The laccase activity of combined fungi of strain 55 (Trametes trogii) and strain m-6 (Trametes versicolor) were 24.13 and 4.07-fold higher than that of strain 55 and strain m-6, respectively. No inhibitory effect was observed when the two strains were co-cultivated. On plate cultivation, there was hyphal interference in the contact area, where laccase activity was the highest followed by brown pigmentation. In liquid cultivation, strain m-6 played much more important role on enhancement of laccase activity, and the laccase activity of strain 55 by adding strain m-6 was 7.03-fold higher than that of strain m-6 by adding strain 55, furthermore, filter sterilized- and high temperature autoclaved-extracellular substances of strain m-6 could also stimulate strain 55 to excrete more laccase, which led to 6.79-fold and 4. 60-fold increase in laccase activity by adding 20 mL, respectively. The native staining results of Native-PAGE showed that the types of laccase isozymes were not changed when strains were co-cultured, but the concentration of three types increased.

Rapid discrimination of strain-dependent fermentation characteristics among Lactobacillus strains by NMR-based metabolomics of fermented vegetable juice

PubMed Central

Nakamura, Toshihide; Sekiyama, Yasuyo; Kikuchi, Jun

2017-01-01

In this study, we investigated the applicability of NMR-based metabolomics to discriminate strain-dependent fermentation characteristics of lactic acid bacteria (LAB), which are important microorganisms for fermented food production. To evaluate the discrimination capability, six type strains of Lactobacillus species and six additional L. brevis strains were used focusing on i) the difference between homo- and hetero-lactic fermentative species and ii) strain-dependent characteristics within L. brevis. Based on the differences in the metabolite profiles of fermented vegetable juices, non-targeted principal component analysis (PCA) clearly separated the samples into those inoculated with homo- and hetero-lactic fermentative species. The separation was primarily explained by the different levels of dominant metabolites (lactic acid, acetic acid, ethanol, and mannitol). Orthogonal partial least squares discrimination analysis, based on a regions-of-interest (ROIs) approach, revealed the contribution of low-abundance metabolites: acetoin, phenyllactic acid, p-hydroxyphenyllactic acid, glycerophosphocholine, and succinic acid for homolactic fermentation; and ornithine, tyramine, and γ-aminobutyric acid (GABA) for heterolactic fermentation. Furthermore, ROIs-based PCA of seven L. brevis strains separated their strain-dependent fermentation characteristics primarily based on their ability to utilize sucrose and citric acid, and convert glutamic acid and tyrosine into GABA and tyramine, respectively. In conclusion, NMR metabolomics successfully discriminated the fermentation characteristics of the tested strains and provided further information on metabolites responsible for these characteristics, which may impact the taste, aroma, and functional properties of fermented foods. PMID:28759594

Nonclinical and Clinical Enterococcus faecium Strains, but Not Enterococcus faecalis Strains, Have Distinct Structural and Functional Genomic Features

PubMed Central

Kim, Eun Bae

2014-01-01

Certain strains of Enterococcus faecium and Enterococcus faecalis contribute beneficially to animal health and food production, while others are associated with nosocomial infections. To determine whether there are structural and functional genomic features that are distinct between nonclinical (NC) and clinical (CL) strains of those species, we analyzed the genomes of 31 E. faecium and 38 E. faecalis strains. Hierarchical clustering of 7,017 orthologs found in the E. faecium pangenome revealed that NC strains clustered into two clades and are distinct from CL strains. NC E. faecium genomes are significantly smaller than CL genomes, and this difference was partly explained by significantly fewer mobile genetic elements (ME), virulence factors (VF), and antibiotic resistance (AR) genes. E. faecium ortholog comparisons identified 68 and 153 genes that are enriched for NC and CL strains, respectively. Proximity analysis showed that CL-enriched loci, and not NC-enriched loci, are more frequently colocalized on the genome with ME. In CL genomes, AR genes are also colocalized with ME, and VF are more frequently associated with CL-enriched loci. Genes in 23 functional groups are also differentially enriched between NC and CL E. faecium genomes. In contrast, differences were not observed between NC and CL E. faecalis genomes despite their having larger genomes than E. faecium. Our findings show that unlike E. faecalis, NC and CL E. faecium strains are equipped with distinct structural and functional genomic features indicative of adaptation to different environments. PMID:24141120

Geometric reconstruction using tracked ultrasound strain imaging

NASA Astrophysics Data System (ADS)

Pheiffer, Thomas S.; Simpson, Amber L.; Ondrake, Janet E.; Miga, Michael I.

2013-03-01

The accurate identification of tumor margins during neurosurgery is a primary concern for the surgeon in order to maximize resection of malignant tissue while preserving normal function. The use of preoperative imaging for guidance is standard of care, but tumor margins are not always clear even when contrast agents are used, and so margins are often determined intraoperatively by visual and tactile feedback. Ultrasound strain imaging creates a quantitative representation of tissue stiffness which can be used in real-time. The information offered by strain imaging can be placed within a conventional image-guidance workflow by tracking the ultrasound probe and calibrating the image plane, which facilitates interpretation of the data by placing it within a common coordinate space with preoperative imaging. Tumor geometry in strain imaging is then directly comparable to the geometry in preoperative imaging. This paper presents a tracked ultrasound strain imaging system capable of co-registering with preoperative tomograms and also of reconstructing a 3D surface using the border of the strain lesion. In a preliminary study using four phantoms with subsurface tumors, tracked strain imaging was registered to preoperative image volumes and then tumor surfaces were reconstructed using contours extracted from strain image slices. The volumes of the phantom tumors reconstructed from tracked strain imaging were approximately between 1.5 to 2.4 cm3, which was similar to the CT volumes of 1.0 to 2.3 cm3. Future work will be done to robustly characterize the reconstruction accuracy of the system.

Anisotropic nature of radially strained metal tubes

NASA Astrophysics Data System (ADS)

Strickland, Julie N.

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

Cells as strain-cued automata

NASA Astrophysics Data System (ADS)

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

Construction of an Optical Fiber Strain Gauge

NASA Astrophysics Data System (ADS)

Sulaiman, Najwa

This project is focused on the construction of an optical fiber strain gauge that is based on a strain gauge described by Butter and Hocker. Our gauge is designed to generate an interference pattern from the signals carried on two bare single-mode fibers that are fastened to an aluminum cantilever. When the cantilever experiences flexural stress, the interference pattern should change. By observing this change, it is possible to determine the strain experienced by the cantilever. I describe the design and construction of our optical fiber strain gauge as well as the characterization of different parts of the apparatus.

Cardiac biplane strain imaging: initial in vivo experience

NASA Astrophysics Data System (ADS)

Lopata, R. G. P.; Nillesen, M. M.; Verrijp, C. N.; Singh, S. K.; Lammens, M. M. Y.; van der Laak, J. A. W. M.; van Wetten, H. B.; Thijssen, J. M.; Kapusta, L.; de Korte, C. L.

2010-02-01

In this study, first we propose a biplane strain imaging method using a commercial ultrasound system, yielding estimation of the strain in three orthogonal directions. Secondly, an animal model of a child's heart was introduced that is suitable to simulate congenital heart disease and was used to test the method in vivo. The proposed approach can serve as a framework to monitor the development of cardiac hypertrophy and fibrosis. A 2D strain estimation technique using radio frequency (RF) ultrasound data was applied. Biplane image acquisition was performed at a relatively low frame rate (<100 Hz) using a commercial platform with an RF interface. For testing the method in vivo, biplane image sequences of the heart were recorded during the cardiac cycle in four dogs with an aortic stenosis. Initial results reveal the feasibility of measuring large radial, circumferential and longitudinal cumulative strain (up to 70%) at a frame rate of 100 Hz. Mean radial strain curves of a manually segmented region-of-interest in the infero-lateral wall show excellent correlation between the measured strain curves acquired in two perpendicular planes. Furthermore, the results show the feasibility and reproducibility of assessing radial, circumferential and longitudinal strains simultaneously. In this preliminary study, three beagles developed an elevated pressure gradient over the aortic valve (Δp: 100-200 mmHg) and myocardial hypertrophy. One dog did not develop any sign of hypertrophy (Δp = 20 mmHg). Initial strain (rate) results showed that the maximum strain (rate) decreased with increasing valvular stenosis (-50%), which is in accordance with previous studies. Histological findings corroborated these results and showed an increase in fibrotic tissue for the hearts with larger pressure gradients (100, 200 mmHg), as well as lower strain and strain rate values.

A strain-cue hypothesis for biological network formation

PubMed Central

Cox, Brian N.

2011-01-01

The direction of migration of a cell invading a host population is assumed to be controlled by the magnitude of the strains in the host medium (cells plus extracellular matrix) that arise as the host medium deforms to accommodate the invader. The single assumption that invaders are cued by strains external to themselves is sufficient to generate network structures. The strain induced by a line of invaders is greatest at the extremity of the line and thus the strain field breaks symmetry, stabilizing branch formation. The strain cue also triggers sprouting from existing branches, with no further model assumption. Network characteristics depend primarily on the ratio of the rate of advance of the invaders to the rate of relaxation of the host cells after their initial deformation. Intra-cell mechanisms that govern these two rates control network morphology. The strain field that cues an individual invader is a collective response of the combined cell populations, involving the nearest 100 cells, to order of magnitude, to any invader. The mechanism does not rely on the pre-existence of the entire host medium prior to invasion; the host cells need only maintain a layer several cells thick around each invader. Consistent with recent experiments, networks result only from a strain cue that is based on strain magnitudes. Spatial strain gradients do not break symmetry and therefore cannot stabilize branch formation. The theory recreates most of the geometrical features of the nervous network in the mouse gut when the most influential adjustable parameter takes a value consistent with one inferred from human and mouse amelogenesis. Because of similarity in the guiding local strain fields, strain cues could also be a participating factor in the formation of vascular networks. PMID:20671068

High-Temperature Strain Sensing for Aerospace Applications

NASA Technical Reports Server (NTRS)

Piazza, Anthony; Richards, Lance W.; Hudson, Larry D.

2008-01-01

Thermal protection systems (TPS) and hot structures are utilizing advanced materials that operate at temperatures that exceed abilities to measure structural performance. Robust strain sensors that operate accurately and reliably beyond 1800 F are needed but do not exist. These shortcomings hinder the ability to validate analysis and modeling techniques and hinders the ability to optimize structural designs. This presentation examines high-temperature strain sensing for aerospace applications and, more specifically, seeks to provide strain data for validating finite element models and thermal-structural analyses. Efforts have been made to develop sensor attachment techniques for relevant structural materials at the small test specimen level and to perform laboratory tests to characterize sensor and generate corrections to apply to indicated strains. Areas highlighted in this presentation include sensors, sensor attachment techniques, laboratory evaluation/characterization of strain measurement, and sensor use in large-scale structures.

Genome Sequencing of Listeria monocytogenes “Quargel” Listeriosis Outbreak Strains Reveals Two Different Strains with Distinct In Vitro Virulence Potential

PubMed Central

Rychli, Kathrin; Müller, Anneliese; Zaiser, Andreas; Schoder, Dagmar; Allerberger, Franz; Wagner, Martin; Schmitz-Esser, Stephan

2014-01-01

A large listeriosis outbreak occurred in Austria, Germany and the Czech Republic in 2009 and 2010. The outbreak was traced back to a traditional Austrian curd cheese called “Quargel” which was contaminated with two distinct serovar 1/2a Listeria monocytogenes strains (QOC1 and QOC2). In this study we sequenced and analysed the genomes of both outbreak strains in order to investigate the extent of genetic diversity between the two strains belonging to MLST sequence types 398 (QOC2) and 403 (QOC1). Both genomes are highly similar, but also display distinct properties: The QOC1 genome is approximately 74 kbp larger than the QOC2 genome. In addition, the strains harbour 93 (QOC1) and 45 (QOC2) genes encoding strain-specific proteins. A 21 kbp region showing highest similarity to plasmid pLMIV encoding three putative internalins is integrated in the QOC1 genome. In contrast to QOC1, strain QOC2 harbours a vip homologue, which encodes a LPXTG surface protein involved in cell invasion. In accordance, in vitro virulence assays revealed distinct differences in invasion efficiency and intracellular proliferation within different cell types. The higher virulence potential of QOC1 in non-phagocytic cells may be explained by the presence of additional internalins in the pLMIV-like region, whereas the higher invasion capability of QOC2 into phagocytic cells may be due to the presence of a vip homologue. In addition, both strains show differences in stress-related gene content. Strain QOC1 encodes a so-called stress survival islet 1, whereas strain QOC2 harbours a homologue of the uncharacterized LMOf2365_0481 gene. Consistently, QOC1 shows higher resistance to acidic, alkaline and gastric stress. In conclusion, our results show that strain QOC1 and QOC2 are distinct and did not recently evolve from a common ancestor. PMID:24587155

Forming Ganymede’s grooves at smaller strain: Toward a self-consistent local and global strain history for Ganymede

USGS Publications Warehouse

Bland, Michael T.; McKinnon, W. B.

2015-01-01

The ubiquity of tectonic features formed in extension, and the apparent absence of ones formed in contraction, has led to the hypothesis that Ganymede has undergone global expansion in its past. Determining the magnitude of such expansion is challenging however, and extrapolation of locally or regionally inferred strains to global scales often results in strain estimates that exceed those based on global constraints. Here we use numerical simulations of groove terrain formation to develop a strain history for Ganymede that is generally consistent at local, regional, and global scales. These simulations reproduce groove-like amplitudes, wavelengths, and average slopes at modest regional extensions (10–15%). The modest strains are more consistent with global constraints on Ganymede’s expansion. Yet locally, we also find that surface strains can be much larger (30–60%) in the same simulations, consistent with observations of highly-extended impact craters. Thus our simulations satisfy both the smallest-scale and largest-scale inferences of strain on Ganymede. The growth rate of the topography is consistent with (or exceeds) predictions of analytical models, and results from the use of a non-associated plastic rheology that naturally permits localization of brittle failure (plastic strain) into linear fault-like shear zones. These fault-like zones are organized into periodically-spaced graben-like structures with stepped, steeply-dipping faults. As in previous work, groove amplitudes and wavelengths depend on both the imposed heat flux and surface temperature, but because our brittle strength increases with depth, we find (for the parameters explored) that the growth rate of topography is initially faster for lower heat flows. We observe a transition to narrow rifting for higher heat flows and larger strains, which is a potential pathway for breakaway margin or band formation.

Premixed Edge-Flames in Spatially-Varying Straining Flows

NASA Technical Reports Server (NTRS)

Liu, Jian-Bang; Ronney, Paul D.

1999-01-01

Flames subject to temporally and spatially uniform hydrodynamic strain are frequently used to model the local interactions of flame fronts with turbulent flow fields (Williams, 1985; Peters, 1986; Bradley, 1992). The applicability of laminar flamelet models in strongly turbulent flows have been questioned recently (Shay and Ronney, 1998) because in turbulent flows the strain rate (sigma) changes at rates comparable to sigma itself and the scale over which the flame front curvature and sigma changes is comparable to the curvature scale itself. Therefore quasi-static, local models of turbulent strain and curvature effects on laminar flamelets may not be accurate under conditions where the strain and curvature effects are most significant. The purpose of this study is to examine flames in spatially-varying strain and compare their properties to those of uniformly strained flames.

Flexible Bond Wire Capacitive Strain Sensor for Vehicle Tyres

PubMed Central

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

2016-01-01

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

Flexible Bond Wire Capacitive Strain Sensor for Vehicle Tyres.

PubMed

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

2016-06-21

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.

Life-course Financial Strain and Health in African-Americans

PubMed Central

Thorpe, Roland J; Whitfield, Keith E

2010-01-01

Differential exposure to financial strain may explain some differences in population health. However, few studies have examined the cumulative health effect of financial strain across the life-course. Studies that have are limited to self-reported health measures. Our objective was to examine the associations between childhood, adulthood, and life-course, or cumulative, financial strain with disability, lung function, cognition, and depression. In a population-based cross-sectional cohort study of adult African-American twins enrolled in the US Carolina African American Twin Study of Aging (CAATSA), we found that participants who reported financial strain as children and as adults are more likely to be physically disabled, and report more depressive symptoms than their unstrained counterparts. Participants who reported childhood financial strain had lower cognitive functioning than those with no childhood financial strain. We were unable to detect a difference in lung function beyond the effect of actual income and education in those who reported financial strain compared to those who did not. Financial strain in adulthood was more consistently associated with poor health than was childhood financial strain, a finding that suggests targeting adult financial strain could help prevent disability and depression among African-American adults. PMID:20452712

Thoracolumbar spinal ligaments exhibit negative and transverse pre-strain.

PubMed

Robertson, Daniel J; Von Forell, Gregory A; Alsup, Jeremy; Bowden, Anton E

2013-07-01

The present work represents the first reported bi-axial spinal ligament pre-strain data for the thoracic and lumbar spine. Ligament pre-strain (in-situ strain) is known to significantly alter joint biomechanics. However, there is currently a lack of comprehensive data with regards to spinal ligament pre-strain. The current work determined the pre-strain of 71 spinal ligaments (30 anterior longitudinal ligaments, 27 supraspinous ligaments and 14 interspinous ligaments). The interspinous ligament and the anterior longitudinal ligament exhibited bi-axial pre-strain distributions, demonstrating they are not uniaxial structures. The supraspinous ligament frequently exhibited large amounts of negative pre-strain or laxity suggesting it makes no mechanical contribution to spinal stability near the neutral posture. Upon implementing multi-axial pre-strain results into a finite element model of the lumbar spine, large differences in spinal biomechanics were observed. These results demonstrate the necessity of accounting for ligament pre-strain in biomechanical models. In addition, the authors present a unique experimental method for obtaining ligament pre-strain that presents a number of advantages when compared to standard techniques. Copyright © 2013 Elsevier Ltd. All rights reserved.

Antimicrobial activity of lactobacillus strains against uropathogens.

PubMed

Shim, Yoon Hee; Lee, Seung Joo; Lee, Jung Won

2016-10-01

The use of lactobacillus probiotics has been proposed as an alternative to prophylactic antibiotics for preventing urinary tract infection (UTI) in the era of antibiotic resistance. In this study, the antimicrobial activity of lactobacillus strains against uropathogens, was evaluated and compared with that of antibiotics. To evaluate inhibitory activities of lactobacilli against uropathogens, six lactobacillus strains (L. gasseri, L. rhamnosus, L. acidophilus, L. plantarum, L. paracasei, L. acidophilus) and four representative uropathogens of infantile UTI (extended-spectrum beta-lactamase [ESBL](-) Escherichia coli, ESBL(+) E. coli, Proteus vulgaris, Enterococcus fecalis) were selected. Lactobacillus strain in vitro inhibition of each uropathogen was evaluated on MRS agar well diffusion assay and compared with that of commercial antibiotic discs. Average inhibitory zone for each of the six lactobacillus strains against the four uropathogens showed slightly different but consistent inhibition (inhibitory zone diameter, 10.5-20.0 mm). This was different to that of the antibiotic discs, which had a wider range of inhibition (inhibitory zone diameter, <6.0-27.5 mm) depending on the uropathogen resistance pattern. The inhibitory zone of the six lactobacillus strains was between that of sensitive and resistant antibiotics (P < 0.05). Lactobacillus strains had similar moderate antimicrobial activities against uropathogens. Further research is needed to ascertain the strains with the best probiotic potential. © 2016 Japan Pediatric Society.

High-Strain-Rate Compression Testing of Ice

NASA Technical Reports Server (NTRS)

Shazly, Mostafa; Prakash, Vikas; Lerch, Bradley A.

2006-01-01

In the present study a modified split Hopkinson pressure bar (SHPB) was employed to study the effect of strain rate on the dynamic material response of ice. Disk-shaped ice specimens with flat, parallel end faces were either provided by Dartmouth College (Hanover, NH) or grown at Case Western Reserve University (Cleveland, OH). The SHPB was adapted to perform tests at high strain rates in the range 60 to 1400/s at test temperatures of -10 and -30 C. Experimental results showed that the strength of ice increases with increasing strain rates and this occurs over a change in strain rate of five orders of magnitude. Under these strain rate conditions the ice microstructure has a slight influence on the strength, but it is much less than the influence it has under quasi-static loading conditions. End constraint and frictional effects do not influence the compression tests like they do at slower strain rates, and therefore the diameter/thickness ratio of the samples is not as critical. The strength of ice at high strain rates was found to increase with decreasing test temperatures. Ice has been identified as a potential source of debris to impact the shuttle; data presented in this report can be used to validate and/or develop material models for ice impact analyses for shuttle Return to Flight efforts.

Comparison of the live attenuated yellow fever vaccine 17D-204 strain to its virulent parental strain Asibi by deep sequencing.

PubMed

Beck, Andrew; Tesh, Robert B; Wood, Thomas G; Widen, Steven G; Ryman, Kate D; Barrett, Alan D T

2014-02-01

The first comparison of a live RNA viral vaccine strain to its wild-type parental strain by deep sequencing is presented using as a model the yellow fever virus (YFV) live vaccine strain 17D-204 and its wild-type parental strain, Asibi. The YFV 17D-204 vaccine genome was compared to that of the parental strain Asibi by massively parallel methods. Variability was compared on multiple scales of the viral genomes. A modeled exploration of small-frequency variants was performed to reconstruct plausible regions of mutational plasticity. Overt quasispecies diversity is a feature of the parental strain, whereas the live vaccine strain lacks diversity according to multiple independent measurements. A lack of attenuating mutations in the Asibi population relative to that of 17D-204 was observed, demonstrating that the vaccine strain was derived by discrete mutation of Asibi and not by selection of genomes in the wild-type population. Relative quasispecies structure is a plausible correlate of attenuation for live viral vaccines. Analyses such as these of attenuated viruses improve our understanding of the molecular basis of vaccine attenuation and provide critical information on the stability of live vaccines and the risk of reversion to virulence.

Strain Hardening of Hadfield Manganese Steel

NASA Astrophysics Data System (ADS)

Adler, P. H.; Olson, G. B.; Owen, W. S.

1986-10-01

The plastic flow behavior of Hadfield manganese steel in uniaxial tension and compression is shown to be greatly influenced by transformation plasticity phenomena. Changes in the stress-strain (σ-ɛ) curves with temperature correlate with the observed extent of deformation twinning, consistent with a softening effect of twinning as a deformation mechanism and a hardening effect of the twinned microstructure. The combined effects give upward curvature to the σ-ɛ curve over extensive ranges of plastic strain. A higher strain hardening in compression compared with tension appears to be consistent with the observed texture development. The composition dependence of stacking fault energy computed using a thermodynamic model suggests that the Hadfield composition is optimum for a maximum rate of deformation twinning. Comparisons of the Hadfield steel with a Co-33Ni alloy exhibiting similar twinning kinetics, and an Fe-21Ni-lC alloy deforming by slip indicate no unusual strain hardening at low strains where deformation is controlled by slip, but an unusual amount of structural hardening associated with the twin formation in the Hadfield steel. A possible mechanism of anomalous twin hardening is discussed in terms of modified twinning behavior (pseudotwinning) in nonrandom solid solutions.

Strain analysis of SiGe microbridges

NASA Astrophysics Data System (ADS)

Anthony, Ross; Gilbank, Ashley; Crowe, Iain; Knights, Andrew

2018-02-01

We present the analysis of UV (325 nm) Raman scattering spectra from silicon-germanium (SiGe) microbridges where the SiGe has been formed using the so-called "condensation technique". As opposed to the conventional condensation technique in which SiGe is grown epitaxially, we use high-dose ion implantation of Ge ions into SOI as a means to introduce the initial Ge profile. The subsequent oxidation both repairs implantation induced damage, and forms epitaxial Ge. Using Si-Si and Si-Ge optical phonon modes, as well as the ratio of integrated intensities for Ge-Ge and Si-Si, we can determine both the composition and strain of the material. We show that although the material is compressively strained following condensation, by fabricating microbridge structures we can create strain relaxed or tensile strained structures, with subsequent interest for photonic applications.

Measuring systolic ankle and toe pressure using the strain gauge technique--a comparison study between mercury and indium-gallium strain gauges.

PubMed

Broholm, Rikke; Wiinberg, Niels; Simonsen, Lene

2014-09-01

Measurement of the ankle and toe pressures are often performed using a plethysmograph, compression cuffs and a strain gauge. Usually, the strain gauge contains mercury but other alternatives exist. From 2014, the mercury-containing strain gauge will no longer be available in the European Union. The aim of this study was to compare an indium-gallium strain gauge to the established mercury-containing strain gauge. Consecutive patients referred to the Department of Clinical Physiology and Nuclear Medicine at Bispebjerg and Frederiksberg Hospitals for measurements of systolic ankle and toe pressures volunteered for the study. Ankle and toe pressures were measured twice with the mercury and the indium-gallium strain gauge in random order. Comparison of the correlation between the mean pressure using the mercury and the indium-gallium device and the difference between the two devices was performed for both toe and ankle level. A total of 53 patients were included (36 male). Mean age was 69 (range, 45-92 years). Mean pressures at toe and ankle level with the mercury and the indium-gallium strain gauges were 77 (range, 0-180) mm Hg and 113 (range, 15-190) mm Hg, respectively. Comparison between the mercury and the indium-gallium strain gauge showed a difference in toe blood pressure values of - 0.7 mm Hg (SD: 7.0). At the ankle level, a difference of 2.0 mm Hg (SD: 8.6) was found. The two different devices agree sufficiently in the measurements of systolic ankle and toe pressure for the indium-gallium strain gauge to replace the mercury strain gauge.

Description of the Klemperer wing strain meter (accelerometer)

NASA Technical Reports Server (NTRS)

1922-01-01

The wing strain meter enables a pilot to know the strain on lifting surfaces and to warn him of the safe limits which may not be exceeded. In wing strain the most important factors are the force of gravity and the force of lift which gives the measure of the sustaining force, and their components which are perpendicular to the lifting surfaces. This reports methods for using the wing strain meter.

Legionella pneumophila pangenome reveals strain-specific virulence factors.

PubMed

D'Auria, Giuseppe; Jiménez-Hernández, Nuria; Peris-Bondia, Francesc; Moya, Andrés; Latorre, Amparo

2010-03-17

Legionella pneumophila subsp. pneumophila is a gram-negative gamma-Proteobacterium and the causative agent of Legionnaires' disease, a form of epidemic pneumonia. It has a water-related life cycle. In industrialized cities L. pneumophila is commonly encountered in refrigeration towers and water pipes. Infection is always via infected aerosols to humans. Although many efforts have been made to eradicate Legionella from buildings, it still contaminates the water systems. The town of Alcoy (Valencian Region, Spain) has had recurrent outbreaks since 1999. The strain "Alcoy 2300/99" is a particularly persistent and recurrent strain that was isolated during one of the most significant outbreaks between the years 1999-2000. We have sequenced the genome of the particularly persistent L. pneumophila strain Alcoy 2300/99 and have compared it with four previously sequenced strains known as Philadelphia (USA), Lens (France), Paris (France) and Corby (England).Pangenome analysis facilitated the identification of strain-specific features, as well as some that are shared by two or more strains. We identified: (1) three islands related to anti-drug resistance systems; (2) a system for transport and secretion of heavy metals; (3) three systems related to DNA transfer; (4) two CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) systems, known to provide resistance against phage infections, one similar in the Lens and Alcoy strains, and another specific to the Paris strain; and (5) seven islands of phage-related proteins, five of which seem to be strain-specific and two shared. The dispensable genome disclosed by the pangenomic analysis seems to be a reservoir of new traits that have mainly been acquired by horizontal gene transfer and could confer evolutionary advantages over strains lacking them.

Strain tolerance in technical Nb3Al superconductors

NASA Astrophysics Data System (ADS)

Banno, N.; Takeuchi, T.; Kitaguchi, H.; Tagawa, K.

2006-10-01

We observed crack formation in transformation-processed Nb3Al wires at room temperature, the wire being bent with a small clamp fixture with a curvature. The polished cross-section parallel to the longitudinal axis was observed, using a high power optical microscope or a field-emission scanning electron microscope. The bend strain limit for microcrack formation is found, changing the radius of the curvature of the clamp. The bend strain limit was found to be around 0.3% for standard Nb3Al wires. This corresponds to the irreversible tensile strain limit of the Ic characteristics determined with a 0.1 µV cm-1 criterion. Reduction of the barrier thickness should be avoided to keep to the bend strain limit. A new configuration of the Nb3Al wire is demonstrated to improve the bend strain limit. The filament is divided into segments in the transverse cross-section. The wire is fabricated by a double-stacking method. The bend strain limit is enhanced to about 0.85% for the wire surface; the equivalent strain of the outermost filament location is about 0.66%. A simple react and wind test for this wire was performed, where the wire experienced 0.86% bend strain. The degradation of Jc was found to be very small.

Antibacterial activity of extracellular compounds produced by a Pseudomonas strain against methicillin-resistant Staphylococcus aureus (MRSA) strains

PubMed Central

2013-01-01

Background The emergence of multidrug-resistant bacteria is a world health problem. Staphylococcus aureus, including methicillin-resistant S. aureus (MRSA) strains, is one of the most important human pathogens associated with hospital and community-acquired infections. The aim of this work was to evaluate the antibacterial activity of a Pseudomonas aeruginosa-derived compound against MRSA strains. Methods Thirty clinical MRSA strains were isolated, and three standard MRSA strains were evaluated. The extracellular compounds were purified by vacuum liquid chromatography. Evaluation of antibacterial activity was performed by agar diffusion technique, determination of the minimal inhibitory concentration, curve of growth and viability and scanning electron microscopy. Interaction of an extracellular compound with silver nanoparticle was studied to evaluate antibacterial effect. Results The F3 (ethyl acetate) and F3d (dichloromethane- ethyl acetate) fractions demonstrated antibacterial activity against the MRSA strains. Phenazine-1-carboxamide was identified and purified from the F3d fraction and demonstrated slight antibacterial activity against MRSA, and synergic effect when combined with silver nanoparticles produced by Fusarium oxysporum. Organohalogen compound was purified from this fraction showing high antibacterial effect. Using scanning electron microscopy, we show that the F3d fraction caused morphological changes to the cell wall of the MRSA strains. Conclusions These results suggest that P. aeruginosa-produced compounds such as phenazines have inhibitory effects against MRSA and may be a good alternative treatment to control infections caused by MRSA. PMID:23773484

How strained are carbomeric-cycloalkanes?

PubMed

Wodrich, Matthew D; Gonthier, Jérôme F; Steinmann, Stephan N; Corminboeuf, Clémence

2010-06-24

The ring strain energies of carbomeric-cycloalkanes (molecules with one or more acetylene spacer units placed into carbon single bonds) are assessed using a series of isodesmic, homodesmotic, and hyperhomodesmotic chemical equations. Isodesmic bond separation reactions and other equations derived from the explicitly defined hierarchy of homodesmotic equations are insufficient for accurately determining these values, since not all perturbing effects (i.e., conjugation and hyperconjugation) are fully balanced. A set of homodesmotic reactions is proposed, which succeeds in balancing all stereoelectronic effects present within the carbomeric rings, allowing for a direct assessment of the strain energies. Values calculated from chemical equations are validated using an increment/additivity approach. The ring strain energy decreases as acetylene units are added, manifesting from the net stabilization gained by opening the C-CH(2)-C angle around the methylene groups and the destabilization arising from bending the C-C identical withC angles of the spacer groups. This destabilization vanishes with increasing parent ring size (i.e., the angle distortion is less in the carbomeric-cyclobutanes than in the carbomeric-cyclopropanes), leading to strain energies near zero for carbo(n)-cyclopentanes and carbo(n)-cyclohexanes.

Strain accumulation in southern California, 1973-1980.

USGS Publications Warehouse

Savage, J.C.; Prescott, W.H.; Lisowski, M.; King, N.E.

1981-01-01

Frequent surveys of seven trilateration networks in southern California over the interval 1973-1980 suggest that a regional increment in strain may have occurred in 1978-1979. Prior to 1978 and after late 1979 the strain accumulation has been predominantly a uniaxial north-south compression. This secular trend was interrupted sometime in 1978-1979 by an increment in both north-south and east-west extension in five of the seven networks. The onset of this change appears to have occurred first in the networks farthest south. The changes occurred without any unusual seismicity within the networks, but the overall seismicity in southern California was unusually low prior to and has been unusually high since the occurrence. The average principal strain rates for the seven networks in the 1973-1980 interval are 0.17 mu strain/yr north- south contraction and 0.08 mu strain/yr east-west extension. Although the observed increment in strain could be related to unidentified systematic error in the measuring system, a careful review of the measurements and comparisons with three other measuring systems reveal no appreciable cumulative systematic error. -Authors

Potentially probiotic Lactobacillus strains from traditional Kurdish cheese.

PubMed

Hashemi, Seyed Mohammad Bagher; Shahidi, Fakhri; Mortazavi, Seyed Ali; Milani, Elnaz; Eshaghi, Zarrin

2014-03-01

In this study, the probiotic potential of Lactobacillus strains isolated from traditional Kurdish cheese was investigated. The Lactobacillus strains were examined for resistance to gastric acidity and bile toxicity, antimicrobial activities, autoaggregation, coaggregation, hydrophobicity, adhesion to Caco-2 cells, and antibiotic susceptibility. The results showed that all strains tested tolerate acid gastric conditions (pH 2.0 and 3.0), and all of them were bile resistant (at 0.3 and 1% concentration). Although no antibacterial activity was detected in vitro assay for the treated (neutralized to pH 6.5 and treated with catalase) cell-free culture supernatant (CFCS) of strains, untreated CFCS showed strong antagonistic activity against two known pathogens bacteria. All strains exhibited a strong autoaggregating phenotype and manifested a high degree of coaggregation with pathogens. On the other hand, majority of studied strains were found sensitive to different antibiotics, such as ampicillin, penicillin, ciprofloxacin, chloramphenicol, erythromycin, rifampicin, and tetracycline, and were resistant to vancomycin and streptomycin. Finally, isolated strains showed good hydrophobicity and adherence to Caco-2 cell line, so they could be exploited for food manufacture.

Genetic engineering of industrial strains of Saccharomyces cerevisiae.

PubMed

Le Borgne, Sylvie

2012-01-01

Genetic engineering has been successfully applied to Saccharomyces cerevisiae laboratory strains for different purposes: extension of substrate range, improvement of productivity and yield, elimination of by-products, improvement of process performance and cellular properties, and extension of product range. The potential of genetically engineered yeasts for the massive production of biofuels as bioethanol and other nonfuel products from renewable resources as lignocellulosic biomass hydrolysates has been recognized. For such applications, robust industrial strains of S. cerevisiae have to be used. Here, some relevant genetic and genomic characteristics of industrial strains are discussed in relation to the problematic of the genetic engineering of such strains. General molecular tools applicable to the manipulation of S. cerevisiae industrial strains are presented and examples of genetically engineered industrial strains developed for the production of bioethanol from lignocellulosic biomass are given.

Effects of replicative fitness on competing HIV strains.

PubMed

Chirove, Faraimunashe; Lungu, Edward M

2013-07-01

We develop an n-strain model to show the effects of replicative fitness of competing viral strains exerting selective density-dependant infective pressure on each other. A two strain model is used to illustrate the results. A perturbation technique and numerical simulations were used to establish the existence and stability of steady states. More than one infected steady states governed by the replicative fitness resulted from the model exhibiting either strain replacement or co-infection. We found that the presence of two or more HIV strains could result in a disease-free state that, in general, is not globally stable. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Strain-controlled fatigue of acrylic bone cement.

PubMed

Carter, D R; Gates, E I; Harris, W H

1982-09-01

Monotonic tensile tests and tension-compression fatigue tests were conducted of wet acrylic bone cement specimens at 37 degrees C. All testing was conducted in strain control at a strain rate of 0.02/s. Weibull analysis of the tensile tests indicated that monotonic fracture was governed more strongly by strain than stress. The number of cycles to fatigue failure was also more strongly controlled by strain amplitude than stress amplitude. Specimen porosity distribution played a major role in determining the tensile and fatigue strengths. The degree of data scatter suggests that Weibull analysis of fatigue data may be useful in developing design criteria for the surgical use of bone cement.

Pathogenic Escherichia coli strain discrimination using laser-induced breakdown spectroscopy

NASA Astrophysics Data System (ADS)

Diedrich, Jonathan; Rehse, Steven J.; Palchaudhuri, Sunil

2007-07-01

A pathogenic strain of bacteria, Escherichia coli O157:H7 (enterohemorrhagic E. coli or EHEC), has been analyzed by laser-induced breakdown spectroscopy (LIBS) with nanosecond pulses and compared to three nonpathogenic E. coli strains: a laboratory strain of K-12 (AB), a derivative of the same strain termed HF4714, and an environmental strain, E. coli C (Nino C). A discriminant function analysis (DFA) was performed on the LIBS spectra obtained from live colonies of all four strains. Utilizing the emission intensity of 19 atomic and ionic transitions from trace inorganic elements, the DFA revealed significant differences between EHEC and the Nino C strain, suggesting the possibility of identifying and discriminating the pathogenic strain from commonly occurring environmental strains. EHEC strongly resembled the two K-12 strains, in particular, HF4714, making discrimination between these strains difficult. DFA was also used to analyze spectra from two of the nonpathogenic strains cultured in different media: on a trypticase soy (TS) agar plate and in a liquid TS broth. Strains cultured in different media were identified and effectively discriminated, being more similar than different strains cultured in identical media. All bacteria spectra were completely distinct from spectra obtained from the nutrient medium or ablation substrate alone. The ability to differentiate strains prepared and tested in different environments indicates that matrix effects and background contaminations do not necessarily preclude the use of LIBS to identify bacteria found in a variety of environments or grown under different conditions.

Inversion of the strain-life and strain-stress relationships for use in metal fatigue analysis

NASA Technical Reports Server (NTRS)

Manson, S. S.

1979-01-01

The paper presents closed-form solutions (collocation method and spline-function method) for the constants of the cyclic fatigue life equation so that they can be easily incorporated into cumulative damage analysis. The collocation method involves conformity with the experimental curve at specific life values. The spline-function method is such that the basic life relation is expressed as a two-part function, one applicable at strains above the transition strain (strain at intersection of elastic and plastic lines), the other below. An illustrative example is treated by both methods. It is shown that while the collocation representation has the advantage of simplicity of form, the spline-function representation can be made more accurate over a wider life range, and is simpler to use.

Fiber-Optic Strain Sensors With Linear Characteristics

NASA Technical Reports Server (NTRS)

Egalon, Claudio O.; Rogowski, Robert S.

1993-01-01

Fiber-optic modal domain strain sensors having linear characteristics over wide range of strains proposed. Conceived in effort to improve older fiber-optic strain sensors. Linearity obtained by appropriate choice of design parameters. Pattern of light and dark areas at output end of optical fiber produced by interference between electromagnetic modes in which laser beam propagates in fiber. Photodetector monitors intensity at one point in pattern.

Generating strain signals under consideration of road surface profiles

NASA Astrophysics Data System (ADS)

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.

The amyR-deletion strain of Aspergillus niger CICC2462 is a suitable host strain to express secreted protein with a low background.

PubMed

Zhang, Hui; Wang, Shuang; Zhang, Xiang Xiang; Ji, Wei; Song, Fuping; Zhao, Yue; Li, Jie

2016-04-28

The filamentous fungus Aspergillus niger is widely exploited as an important expression host for industrial production. The glucoamylase high-producing strain A. niger CICC2462 has been used as a host strain for the establishment of a secretion expression system. It expresses recombinant xylanase, mannase and asparaginase at a high level, but some high secretory background proteins in these recombinant strains still remain, such as alpha-amylase and alpha-glucosidase; lead to a low-purity of fermentation products. The aim was to construct an A. niger host strain with a low background of protein secretion. The transcription factor amyR was deleted in A. niger CICC2462, and the results from enzyme activity assays and SDS-PAGE analysis showed that the glucoamylase and amylase activities of the ∆amyR strains were significantly lower than those of the wild-type strain. High-throughput RNA-sequencing and shotgun LC-MS/MS proteomic technology analysis demonstrated that the expression of amylolytic enzymes was decreased at both the transcriptional and translational levels in the ∆amyR strain. Interestingly, the ∆amyR strain growth rate better than the wild-type strain. Our findings clearly indicated that the ∆amyR strain of A. niger CICC2462 can be used as a host strain with a low background of protein secretion.

[Expression and analysis of the nucleoprotein of paramyxovirus Tianjin strain].

PubMed

Wang, Qing; Li, Mei; Shi, Li-Ying; Yuan, Li-Jun; Wang, Wen-Xiu

2008-05-01

Paramyxovirus Tianjin strain is a novel strain of virus causing common cotton-eared marmoset fatal infection. To investigate the relationship between the gene structure and function of nucleoprotein (NP) of Tianjin strain, NP gene of paramyxovirus Tianjin strain was cloned and three domains of NP were expressed. The homologous and phylogenetic analysis of NP sequences among the paramyxovirus Tianjin strain and eight strains of Sendai viruses from GenBank were performed. The results indicated the recombinant proteins NP1, NP2 and NP3 showed the native antigenicity to the polyclonal antiserum of paramyxovirus Tianjin strain, ranking as NP3>NP1>NP2 (precedence order). The homology of NP nucleotide and the deduced amino acid sequences between paramyxovirus Tianjin strain and Sendai virus BB1 strain were 94.5%, 96.2%, respectively, whereas the identity were 85.1% - 88.7% and 92.4% - 94.7% among Tianjin strain and the 7 strains of Sendai viruses from GenBank respectively. There were 15 unique amino acid substitutions in Tianjin strain NP protein and 11 common amino acid substitutions same with BB1 strain. This research confirmed that paramyxovirus Tianjin strain might be a new genotype of Sendai virus and can be helpful in the establishment of detection assay applying recombinant NP as antigen instead of the whole virions.

Life-course financial strain and health in African-Americans.

PubMed

Szanton, Sarah L; Thorpe, Roland J; Whitfield, Keith

2010-07-01

Differential exposure to financial strain may explain some differences in population health. However, few studies have examined the cumulative health effect of financial strain across the life-course. Studies that have are limited to self-reported health measures. Our objective was to examine the associations between childhood, adulthood, and life-course, or cumulative, financial strain with disability, lung function, cognition, and depression. In a population-based cross-sectional cohort study of adult African-American twins enrolled in the US Carolina African American Twin Study of Aging (CAATSA), we found that participants who reported financial strain as children and as adults are more likely to be physically disabled, and report more depressive symptoms than their unstrained counterparts. Participants who reported childhood financial strain had lower cognitive functioning than those with no childhood financial strain. We were unable to detect a difference in lung function beyond the effect of actual income and education in those who reported financial strain compared to those who did not. Financial strain in adulthood was more consistently associated with poor health than was childhood financial strain, a finding that suggests targeting adult financial strain could help prevent disability and depression among African-American adults. Copyright 2010 Elsevier Ltd. All rights reserved.

Can a strain yield a qubit?

NASA Astrophysics Data System (ADS)

Benjamin, Colin

2015-03-01

A Josepshon qubit is designed via the application of a tensile strain to a topological insulator surface, sandwiched between two s-wave superconductors. The strain applied leads to a shift in Dirac point without changing the conducting states existing on the surface of a topological insulator. This strain applied can be tuned to form a π-junction in such a structure. Combining two such junctions in a ring architecture leads to the ground state of the ring being in a doubly degenerate state- ``0'' and ``1'' states of the qubit. A qubit designed this way is easily controlled via the tunable strain. We report on the conditions necessary to design such a qubit. Finally the operating time of a single qubit phase gate is derived. This work was supported by funds from Dept. of Science and Technology (Nanomission), Govt. of India, Grant No. SR/NM/NS-1101/2011.

Material mechanical characterization method for multiple strains and strain rates

DOEpatents

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

2016-01-19

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

Effects of Recovery Behavior and Strain-Rate Dependence of Stress-Strain Curve on Prediction Accuracy of Thermal Stress Analysis During Casting

NASA Astrophysics Data System (ADS)

Motoyama, Yuichi; Shiga, Hidetoshi; Sato, Takeshi; Kambe, Hiroshi; Yoshida, Makoto

2017-06-01

Recovery behavior (recovery) and strain-rate dependence of the stress-strain curve (strain-rate dependence) are incorporated into constitutive equations of alloys to predict residual stress and thermal stress during casting. Nevertheless, few studies have systematically investigated the effects of these metallurgical phenomena on the prediction accuracy of thermal stress in a casting. This study compares the thermal stress analysis results with in situ thermal stress measurement results of an Al-Si-Cu specimen during casting. The results underscore the importance for the alloy constitutive equation of incorporating strain-rate dependence to predict thermal stress that develops at high temperatures where the alloy shows strong strain-rate dependence of the stress-strain curve. However, the prediction accuracy of the thermal stress developed at low temperatures did not improve by considering the strain-rate dependence. Incorporating recovery into the constitutive equation improved the accuracy of the simulated thermal stress at low temperatures. Results of comparison implied that the constitutive equation should include strain-rate dependence to simulate defects that develop from thermal stress at high temperatures, such as hot tearing and hot cracking. Recovery should be incorporated into the alloy constitutive equation to predict the casting residual stress and deformation caused by the thermal stress developed mainly in the low temperature range.

Comparison of the Live Attenuated Yellow Fever Vaccine 17D-204 Strain to Its Virulent Parental Strain Asibi by Deep Sequencing

PubMed Central

Beck, Andrew; Tesh, Robert B.; Wood, Thomas G.; Widen, Steven G.; Ryman, Kate D.; Barrett, Alan D. T.

2014-01-01

Background. The first comparison of a live RNA viral vaccine strain to its wild-type parental strain by deep sequencing is presented using as a model the yellow fever virus (YFV) live vaccine strain 17D-204 and its wild-type parental strain, Asibi. Methods. The YFV 17D-204 vaccine genome was compared to that of the parental strain Asibi by massively parallel methods. Variability was compared on multiple scales of the viral genomes. A modeled exploration of small-frequency variants was performed to reconstruct plausible regions of mutational plasticity. Results. Overt quasispecies diversity is a feature of the parental strain, whereas the live vaccine strain lacks diversity according to multiple independent measurements. A lack of attenuating mutations in the Asibi population relative to that of 17D-204 was observed, demonstrating that the vaccine strain was derived by discrete mutation of Asibi and not by selection of genomes in the wild-type population. Conclusions. Relative quasispecies structure is a plausible correlate of attenuation for live viral vaccines. Analyses such as these of attenuated viruses improve our understanding of the molecular basis of vaccine attenuation and provide critical information on the stability of live vaccines and the risk of reversion to virulence. PMID:24141982

Escherichia coli strain Nissle 1917-from bench to bedside and back: history of a special Escherichia coli strain with probiotic properties.

PubMed

Sonnenborn, Ulrich

2016-10-01

Among the gram-negative microorganisms with probiotic properties, Escherichia coli strain Nissle 1917 (briefly EcN) is probably the most intensively investigated bacterial strain today. Since nearly 100 years, the EcN strain is used as the active pharmaceutical ingredient in a licensed medicinal product that is distributed in Germany and several other countries. Over the last few decades, novel probiotic activities have been detected, which taken together are specific of this versatile E. coli strain. This review gives a short overview on the discovery and history of the EcN strain. © FEMS 2016. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Discerning strain effects in microbial dose-response data.

PubMed

Coleman, Margaret E; Marks, Harry M; Golden, Neal J; Latimer, Heejeong K

In order to estimate the risk or probability of adverse events in risk assessment, it is necessary to identify the important variables that contribute to the risk and provide descriptions of distributions of these variables for well-defined populations. One component of modeling dose response that can create uncertainty is the inherent genetic variability among pathogenic bacteria. For many microbial risk assessments, the "default" assumption used for dose response does not account for strain or serotype variability in pathogenicity and virulence, other than perhaps, recognizing the existence of avirulent strains. However, an examination of data sets from human clinical trials in which Salmonella spp. and Campylobacter jejuni strains were administered reveals significant strain differences. This article discusses the evidence for strain variability and concludes that more biologically based alternatives are necessary to replace the default assumptions commonly used in microbial risk assessment, specifically regarding strain variability.

Closure of fatigue cracks at high strains

NASA Technical Reports Server (NTRS)

Iyyer, N. S.; Dowling, N. E.

1985-01-01

Experiments were conducted on smooth specimens to study the closure behavior of short cracks at high cyclic strains under completely reversed cycling. Testing procedures and methodology, and closure measurement techniques, are described in detail. The strain levels chosen for the study cover from predominantly elastic to grossly plastic strains. Crack closure measurements are made at different crack lengths. The study reveals that, at high strains, cracks close only as the lowest stress level in the cycle is approached. The crack opening is observed to occur in the compressive part of the loading cycle. The applied stress needed to open a short crack under high strain is found to be less than for cracks under small scale yielding. For increased plastic deformations, the value of sigma sub op/sigma sub max is observed to decrease and approaches the value of R. Comparison of the experimental results with existing analysis is made and indicates the limitations of the small scale yielding approach where gross plastic deformation behavior occurs.

[New antibiotics produced by Bacillus subtilis strains].

PubMed

Malanicheva, I A; Kozlov, D G; Efimenko, T A; Zenkova, V A; Kastrukha, G S; Reznikova, M I; Korolev, A M; Borshchevskaia, L N; Tarasova, O D; Sineokiĭ, S P; Efremenkova, O V

2014-01-01

Two Bacillus subtilis strains isolated from the fruiting body of a basidiomycete fungus Pholiota squarrosa exhibited a broad range of antibacterial activity, including those against methicillin-resistant Staphylococcus aureus INA 00761 (MRSA) and Leuconostoc mes6nteroides VKPM B-4177 resistant to glycopep-> tide antibiotics, as well as antifungal activity. The strains were identified as belonging to the "B. subtilis" com- plex based on their morphological and physiological characteristics, as well as by sequencing of the 16S rRNA gene fragments. Both strains (INA 01085 and INA 01086) produced insignificant amounts of polyene antibiotics (hexaen and pentaen, respectively). Strain INA 01086 produced also a cyclic polypeptide antibiotic containing Asp, Gly, Leu, Pro, Tyr, Thr, Trp, and Phe, while the antibiotic of strain INA 01085 contained, apart from these, two unidentified nonproteinaceous amino acids. Both polypeptide antibiotics were new compounds efficient against gram-positive bacteria and able to override the natural bacterial antibiotic resistance.

Strain rate effects in stress corrosion cracking

DOE Office of Scientific and Technical Information (OSTI.GOV)

Parkins, R.N.

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 maymore » 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.« less

Genomic Analysis of Phylotype I Strain EP1 Reveals Substantial Divergence from Other Strains in the Ralstonia solanacearum Species Complex

PubMed Central

Li, Peng; Wang, Dechen; Yan, Jinli; Zhou, Jianuan; Deng, Yinyue; Jiang, Zide; Cao, Bihao; He, Zifu; Zhang, Lianhui

2016-01-01

Ralstonia solanacearum species complex is a devastating group of phytopathogens with an unusually wide host range and broad geographical distribution. R. solanacearum isolates may differ considerably in various properties including host range and pathogenicity, but the underlying genetic bases remain vague. Here, we conducted the genome sequencing of strain EP1 isolated from Guangdong Province of China, which belongs to phylotype I and is highly virulent to a range of solanaceous crops. Its complete genome contains a 3.95-Mb chromosome and a 2.05-Mb mega-plasmid, which is considerably bigger than reported genomes of other R. solanacearum strains. Both the chromosome and the mega-plasmid have essential house-keeping genes and many virulence genes. Comparative analysis of strain EP1 with other 3 phylotype I and 3 phylotype II, III, IV strains unveiled substantial genome rearrangements, insertions and deletions. Genome sequences are relatively conserved among the 4 phylotype I strains, but more divergent among strains of different phylotypes. Moreover, the strains exhibited considerable variations in their key virulence genes, including those encoding secretion systems and type III effectors. Our results provide valuable information for further elucidation of the genetic basis of diversified virulences and host range of R. solanacearum species. PMID:27833603

Establishment of a nanoparticle-assisted RT-PCR assay to distinguish field strains and attenuated strains of porcine epidemic diarrhea virus.

PubMed

Zhu, Yu; Wang, Gui-Hua; Cui, Yu-Dong; Cui, Shang-Jin

2016-09-01

Porcine epidemic diarrhea virus (PEDV) can cause serious disease and even death in neonatal piglets, resulting in serious damage to the swine industry worldwide. Open reading frame 3 (ORF3) is the only accessory gene in the PEDV genome. Previous studies have indicated that PEDV vaccine strains have a partial deletion in ORF3. In this study, a nanoparticle-assisted polymerase chain reaction (nanoparticle-assisted RT-PCR) assay targeting the ORF3 of PEDV was developed to distinguish PEDV field strains from attenuated strains by using a specific pair of primers. The PCR products of field strains and attenuated strains were 264 bp and 215 bp in length, respectively. The sensitivity and specificity of this assay were also assessed. The nanoparticle-assisted RT-PCR assay was 10-100 times more sensitive than the conventional RT-PCR assay, with no cross-reactions when amplifying porcine pseudorabies virus (PRV), porcine circovirus type 2 (PCV2), classical swine fever virus (CSFV), porcine parvovirus (PPV), porcine reproductive and respiratory syndrome virus (PRRSV), porcine rotavirus (RV), and porcine transmissible gastroenteritis virus (TGEV). The nanoparticle-assisted RT-PCR assay we describe here can be used to distinguish field strains from vaccine strains of PEDV, and it shows promise for reducing economic loss due to PEDV infection.

Maltodextrin Acceptance and Preference in Eight Mouse Strains.

PubMed

Poole, Rachel L; Aleman, Tiffany R; Ellis, Hillary T; Tordoff, Michael G

2016-01-01

Rodents are strongly attracted to the taste(s) of maltodextrins. A first step toward discovery of the underlying genes involves identifying phenotypic differences among inbred strains of mice. To do this, we used 5-s brief-access tests and 48-h 2-bottle choice tests to survey the avidity for the maltodextrin, Maltrin M040, of mice from 8 inbred strains (129S1/SvImJ, A/J, CAST/EiJ, C57BL/6J, NOD/ShiLTJ, NZO/HlLtJ, PWK/PhJ, and WSB/EiJ). In brief-access tests, the CAST and PWK strains licked significantly less maltodextrin than equivalent concentrations of sucrose, whereas the other strains generally licked the 2 carbohydrates equally. Similarly, in 2-bottle choice tests, the CAST and PWK strains drank less 4% maltodextrin than 4% sucrose, whereas the other strains had similar intakes of these 2 solutions; the CAST and PWK strains did not differ from the C57, NOD, or NZO strains in 4% sucrose intake. In sum, we have identified strain variation in maltodextrin perception that is distinct from variation in sucrose perception. The phenotypic variation characterized here will aid in identifying genes responsible for maltodextrin acceptance. Our results identify C57 × PWK mice or NZO × CAST mice as informative crosses to produce segregating hybrids that will expose quantitative trait loci underlying maltodextrin acceptance and preference. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

Strain corrosion cracking in rpm sewer piping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hopkins, S.W.; Wachob, H.F.; Duffner, D.H.

1993-12-31

Long term, aggressive environmental exposure can result in localized failure of large diameter, glass reinforced plastic mortar (RPM) piping. In order to evaluate the performance of the liner and glass reinforced matrix polyester resin, accelerated strain corrosion tests were performed on samples of RPM piping that had already experienced almost 15 years of service. To assess the sensitivity of RPM pipe to acidic environments and to correlate the fractography of the laboratory produced failures with the excavated crack, short segments of 8-inch and 48-inch diameter piping were statically loaded to produce various known surface strains. After preloading the specimens tomore » fixed strain levels, these samples were then exposed to sulfuric acid solutions having pH values of 2.7 and 4.7 and monitored as a function of time until failure. The resulting lifetimes were related to initial surface strains and showed a decreasing logarithmic relationship. Fractographic examination of the excavated crack revealed the typical strain corrosion fractography of glass fibers after almost a 1000 hour exposure at 1.3 % strain; similar fractographic observations were obtained from failed laboratory samples. At shorter times, failure appeared to be overload in nature and exhibited little, if any, timedependent fracture features. Fractographic examination of the excavated crack strongly indicated that the crack had been present for a significant time. The extremely aggressive environment had totally dissolved the exposed glass reinforcement. Based on the laboratory strain corrosion performance, the nature of the contained cracking, and fractography of the failed surface, cracking of the excavated RPM pipe was believed to be the result of an early overload failure that subsequently propagated slowly via strain corrosion in an extremely aggressive environment.« less

Submicron mapping of strained silicon-on-insulator features induced

NASA Astrophysics Data System (ADS)

Murray, Conal E.; Sankarapandian, M.; Polvino, S. M.; Noyan, I. C.; Lai, B.; Cai, Z.

2007-04-01

Real-space maps of strain within silicon-on-insulator (SOI) features induced by adjacent, embedded shallow-trench-isolation (STI) SiO2 regions were obtained using x-ray microbeam diffraction. The quantitative strain mapping indicated that the SOI strain was largest at the SOI/STI interface and decreased as a function of distance from this interface. An out-of-plane residual strain of approximately -31μɛ was observed in the blanket regions of the SOI. A comparison of the depth-averaged strain distributions to the strain profiles calculated from an Eshelby inclusion model indicated an equivalent eigenstrain of -0.55% in the STI regions acting on the SOI features.

Strain-induced negative differential resistance in ultrasmall carbon nanotube

NASA Astrophysics Data System (ADS)

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

2017-08-01

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

Proteomic analysis of Mycoplasma gallisepticum vaccine strain F

USDA-ARS?s Scientific Manuscript database

The persistence and displacement abilities of the Mycoplasma gallisepticum vaccine strain F (F-strain) are well documented. Understanding the mechanism(s) of colonization and persistence of F-strain will aid in the current intervention strategies to diagnose and control MG infections in poultry. In ...

Residual Strain in PCBs with Cu-Plated Holes

NASA Astrophysics Data System (ADS)

Rudajevova, A.; Dušek, K.

2017-12-01

The residual strain in pure printed circuit boards (PCBs) and PCBs with Cu-plated holes has been obtained by measurement of the temperature dependence of their dilatational characteristics in the x, y, and z directions up to 240°C. Shrinkage in all directions was observed for all samples of both materials in the first thermal cycle. No permanent length changes were observed in the second or subsequent thermal cycles. The residual strain was determined from the difference in relative elongation between the first and second thermal cycles. Relaxation of residual strain occurred only in the first thermal cycle, as a thermally activated process. The highest value of relaxed residual strain was found in the z direction for both materials. Relaxation of residual strain in the z direction of the pure PCB occurred only in the negative strain range, whereas relaxation of the PCB with Cu-plated holes occurred in both the positive and negative strain ranges. The relaxation of the positive strain in the PCB with Cu-plated holes in the z direction implies that this part of the PCB was under pressure during its preparation. This relaxation is a consequence of the high coefficient of thermal expansion of PCB laminate in this direction, which can also lead to cracks in Cu holes when the material is heated above the glass-transition temperature.

The premixed flame in uniform straining flow

NASA Technical Reports Server (NTRS)

Durbin, P. A.

1982-01-01

Characteristics of the premixed flame in uniform straining flow are investigated by the technique of activation-energy asymptotics. An inverse method is used, which avoids some of the restrictions of previous analyses. It is shown that this method recovers known results for adiabatic flames. New results for flames with heat loss are obtained, and it is shown that, in the presence of finite heat loss, straining can extinguish flames. A stability analysis shows that straining can suppress the cellular instability of flames with Lewis number less than unity. Strain can produce instability of flames with Lewis number greater than unity. A comparison shows quite good agreement between theoretical deductions and experimental observations of Ishizuka, Miyasaka & Law (1981).

Deoxyribonucleic acid-deficient strains of Candida albicans.

PubMed

Olaiya, A F; Steed, J R; Sogin, S J

1980-03-01

We analyzed a series of germ tube-negative variants isolated from Candida albicans 3153A for deoxyribonucleic acid content. As analyzed by flow microfluorometry, the deoxyribonucleic acid level in these variant strains was 50% of that of the parental strain and equivalent to that of haploid Saccharomyces cerevisiae. This finding was confirmed by comparison of survival rates when exposed to the mutagens ultraviolet light, ethyl methane sulfonate, and methyl methane sulfonate. The diameter of the variant cells as compared to the diameter of the parental 3153A strain showed a relationship similar to that of the diameters of haploid versus diploid S. cerevisiae. These results indicate that those strains may be representative of the imperfect stage of C. albicans.