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Sample records for pulsed field gel

  1. Pulse Field Gel Electrophoresis.

    Science.gov (United States)

    Sharma-Kuinkel, Batu K; Rude, Thomas H; Fowler, Vance G

    2016-01-01

    Pulse Field Gel Electrophoresis (PFGE) is a powerful genotyping technique used for the separation of large DNA molecules (entire genomic DNA) after digesting it with unique restriction enzymes and applying to a gel matrix under the electric field that periodically changes direction. PFGE is a variation of agarose gel electrophoresis that permits analysis of bacterial DNA fragments over an order of magnitude larger than that with conventional restriction enzyme analysis. It provides a good representation of the entire bacterial chromosome in a single gel with a highly reproducible restriction profile, providing clearly distinct and well-resolved DNA fragments.

  2. Pulsed field gel electrophoresis a practical guide

    CERN Document Server

    Birren, Bruce

    1993-01-01

    Pulsed Field Gel Electrophoresis: A Practical Guide is the first laboratory manual to describe the theory and practice of this technique. Based on the authors' experience developing pulsed field gel instruments and teaching procedures, this book provides everything a researcher or student needs to know in order to understand and carry out pulsed field gel experiments. Clear, well-tested protocols assume only that users have a basic familiarity with molecular biology. Thorough coverage of useful data, theory, and applications ensures that this book is also a lasting resource for more adv

  3. Pulsed field gel electrophoresis on frozen tumour tissue sections.

    OpenAIRE

    Boultwood, J; Kaklamanis, L.; Gatter, K C; Wainscoat, J S

    1992-01-01

    The application of pulsed field gel electrophoresis (PFGE) to the molecular genetic analysis of solid tumours has been restricted by the requirement for whole single cells as a DNA source. A simple technique which allows for the direct analysis of histologically characterised solid tumour material by pulsed field gel electrophoresis was developed. Single frozen tissue sections obtained from colonic carcinoma specimens were embedded without further manipulation in molten, low melting temperatu...

  4. Orientation of the agarose gel matrix in pulsed electric fields.

    OpenAIRE

    Stellwagen, J; Stellwagen, N C

    1989-01-01

    The technique of transient electric birefringence was used to investigate the effect of pulsed electric fields on the orientation of the agarose gel matrix. Orientation of the gel was observed at all electric field strengths. Very slow, time-dependent effects were observed when pulses of 10-100 V/cm were applied to 1% gels for 0.5-2 seconds, indicating that domains of the matrix were being oriented by the electric field. The sign of the birefringence reversed when the direction of the applied...

  5. Pulsed-field gel electrophoresis typing of Staphylococcus aureus isolates

    Science.gov (United States)

    Pulsed-field gel electrophoresis (PFGE) is the most applied and effective genetic typing method for epidemiological studies and investigation of foodborne outbreaks caused by different pathogens, including Staphylococcus aureus. The technique relies on analysis of large DNA fragments generated by th...

  6. Pulsed-field gel electrophoresis of bacterial chromosomes.

    Science.gov (United States)

    Mawer, Julia S P; Leach, David R F

    2013-01-01

    The separation of fragments of DNA by agarose gel electrophoresis is integral to laboratory life. Nevertheless, standard agarose gel electrophoresis cannot resolve fragments bigger than 50 kb. Pulsed-field gel electrophoresis is a technique that has been developed to overcome the limitations of standard agarose gel electrophoresis. Entire linear eukaryotic chromosomes, or large fragments of a chromosome that have been generated by the action of rare-cutting restriction endonucleases, can be separated using this technique. As a result, pulsed-field gel electrophoresis has many applications, from karyotype analysis of microbial genomes, to the analysis of chromosomal strand breaks and their repair intermediates, to the study of DNA replication and the identification of origins of replication. This chapter presents a detailed protocol for the preparation of Escherichia coli chromosomal DNA that has been embedded in agarose plugs, digested with the rare-cutting endonuclease NotI, and separated by contour-clamped homogeneous field electrophoresis. The principles in this protocol can be applied to the separation of all fragments of DNA whose size range is between 40 kb and 1 Mb.

  7. Stacking gels: A method for maximising output for pulsed-field gel electrophoresis

    Directory of Open Access Journals (Sweden)

    Heng See

    2009-01-01

    Full Text Available Pulsed field gel electrophoresis (PFGE, the gold standard of molecular typing methods, has a major disadvantage of an unusually long electrophoretic time. From the original protocol of 6 days, it was modified to 3 days and subsequently to a single day. We describe the procedure of stacking five to six gels one on top of another in order to increase and maximize the output in a shorter time without compromising the resolution and reproducibility. All the variables that affect pulsed field gels during electrophoresis were taken into consideration. We firstly optimized the parameters to be used and secondly determined whether stacking of five to six gels had any effect on the molecular separation during electrophoresis in comparison with a single gel run. DNA preparation, restriction, electrophoresis, staining and gel documentation was carried out based on previously published methods. Gels were analysed using BioNumerics and dice coefficient and unweighted pair group methods were used to generate dendrograms based on 1.5% tolerance values. Identical band profiles and band resolution-separation were seen in the PFGE patterns with single gel and multiple stacking gels. Cluster analysis further strengthened the fact that results from stacking gels were reproducible and comparable with a single gel run. This method of stacking gels saves time and maximizes the output at the same time. The run time for a single gel was about 28 hours, but with six stacked gels the run time was 54 hours compared with 28 x 6 = 168 hours if they were run separately as single gels thus saving time of 67.86%. Beside the big factor of saving time, stacking gels save resources (electricity, reagents, water, chemicals and working time by increasing the sample throughput in a shorter time without compromising on quality of data. But optimization of working parameters is vital depending on the PFGE system used.

  8. CHARACTERIZATION OF PATHOGENIC FUNGI GENOMES USING PULSED FIELD GEL ELECTROPHORESIS

    Institute of Scientific and Technical Information of China (English)

    吴绍熙; 郭宁如; 殷正男; 柴建华

    1996-01-01

    Pulsed field gel eleetrophoresis (PFGE) has been firstly introdueed in characterization of the pathogenic fungi Pericillium marneffei and Exophiata dermatitidis genomes. The numbers and sizes of their chromosomes have been detected. Polymorphism was identified on the smallest chromosome of E.derntatitidis. The result shows that PFGE for characterization of large molecular DNA pathogenic fungi is very suitable, it is more simple and more efficacy. The result also shows the diversity of pathogenic fungi is relative common even in rare occurred pathogeafie fungi such as E. dermatitidis.

  9. Epidemiological Typing of Moraxella Catarrhalis by Pulsed Field Gel Electrophoresis

    Directory of Open Access Journals (Sweden)

    Susan M Davison

    1995-01-01

    Full Text Available Pulsed field gel electrophoresis (pfge was used to compare 59 strains of Moraxella catarrhalis to evaluate pfge for the epidemiological typing of this organism. pfge-generated patterns were compared with those obtained by small fragment restriction enzyme analysis (rea and species-specific probe hybridization. The strains used in the study were isolated from various geographic locations and included proven epidemiologically related strains. pfge yielded more unique patterns than dna-dna hybridization – 30 versus 18, respectively – but fewer than rea, which generated 45 unique patterns. Strains that demonstrated the same rea pattern or dna-dna hybridization pattern did not always demonstrate the same pfge pattern. For example, in 23 epidemiologically unrelated strains that shared six rea patterns, pfge differentiated the isolates into 12 patterns. Conversely, strains that demonstrated the same pfge pattern did not always demonstrate the same rea pattern or hybridization pattern. For example, in 42 strains that shared 13 pfge patterns, rea differentiated the isolates into 31 patterns and dna-dna hybridization differentiated them into 16 patterns. However, compared with rea, pfge yielded less complex patterns that were more easily comparable, and compared with dna-dna hybridization, pfge was technically easier.

  10. Amplified fragment length polymorphism and pulsed field gel electrophoresis for subspecies differentiation of Serpulina pilosicoli

    DEFF Research Database (Denmark)

    Møller, Kristian; Jensen, Tim Kåre; Boye, Mette

    1999-01-01

    Pulsed field gel electrophoresis (PFGE) and amplified fragment length polymorphism (AFLP) were compared for their ability to differentiate between 50 porcine Serpulina pilosicoli isolates. Both techniques were highly sensitive, dividing the isolates into 36 and 38 groups, respectively. Due...

  11. Pulsed electric field assisted sol-gel preparation of TiO2 nanoparticles

    Science.gov (United States)

    Mani, Rajaboopathi; Han, Bing; Louhi-Kultanen, Marjatta

    2016-10-01

    This work studies the effect of a pulsed electric field (PEF) on the precipitation and properties of TiO2 nanoparticles. TiO2 nanoparticles were prepared using pulsed DC electric field assisted sol-gel method. The duration of the PEF treatment was varied to investigate its effect on the particle size of TiO2 nanoparticles. The nanoparticles were characterized by X-ray powder diffraction (XRD), Raman spectroscopy, UV diffuse reflectance spectroscopy (UV-DRS) and transmission electron microscopy (TEM). It was found that TiO2 particles prepared with pulsed electric field assisted sol-gel method had enhanced average crystallite size due to the effect of the pulsed electric field on primary nucleation. The effect of electric field on nanoparticle preparation is interesting which can be used to control the grain and crystallite size of nanoparticle.

  12. Inactivation of microorganisms within collagen gel biomatrices using pulsed electric field treatment.

    Science.gov (United States)

    Griffiths, Sarah; Maclean, Michelle; Anderson, John G; MacGregor, Scott J; Grant, M Helen

    2012-02-01

    Pulsed electric field (PEF) treatment was examined as a potential decontamination method for tissue engineering biomatrices by determining the susceptibility of a range of microorganisms whilst within a collagen gel. High intensity pulsed electric fields were applied to collagen gel biomatrices containing either Escherichia coli, Pseudomonas aeruginosa, Staphylococcus epidermidis, Candida albicans, Saccharomyces cerevisiae or the spores of Aspergillus niger. The results established varying degrees of microbial PEF susceptibility. When high initial cell densities (10(6)-10(7) CFU ml(-1)) were PEF treated with 100 pulses at 45 kV cm(-1), the greatest log reduction was achieved with S. cerevisiae (~6.5 log(10) CFU ml(-1)) and the lowest reduction achieved with S. epidermidis (~0.5 log(10) CFU ml(-1)). The results demonstrate that inactivation is influenced by the intrinsic properties of the microorganism treated. Further investigations are required to optimise the microbial inactivation kinetics associated with PEF treatment of collagen gel biomatrices.

  13. Investigating DNA Migration in Pulsed Fields Using a Miniaturized Field Inversion Gel Electrophoresis System

    Science.gov (United States)

    Chen, Xiaojia; Ugaz, Victor M.

    2010-01-01

    Pulsed field gel electrophoresis (PFGE) is a well-established technique for fractionation of DNA fragments ranging from kilobases to megabases in length. But many of these separations require an undesirable combination of long experiment times (often approaching tens of hours) and application of high voltages (often approaching tens of kV). Here we present a simple miniaturized field inversion gel electrophoresis (FIGE) apparatus capable of separating DNA fragments up to 32.5 kb in length within 3 hours using a modest applied potential of 20 V. The device is small enough to be imaged under a fluorescence microscope, permitting the migrating DNA bands to be observed during the course of the separation run. We use this capability to investigate how separation performance is affected by parameters including the ratio of forward and backward voltage, pulse time, and temperature. We also characterize the dependence of DNA mobility on fragment size N, and observe a scaling in the vicinity of N−0.5 over the size range investigated. The high speed, low power consumption, and simple design of this system may help enable future studies of DNA migration in PFGE to be performed quickly and inexpensively. PMID:19053074

  14. Pulsed-field Gel Electrophoresis for Salmonella Infection Surveillance, Texas, USA, 2007

    Centers for Disease Control (CDC) Podcasts

    2010-06-14

    This podcast describes monitoring of the use of pulsed-field gel electrophoresis for Salmonella surveillance in Houston, Texas. CDC microbiologist Peter Gerner-Smidt discusses the importance of the PulseNet national database in surveillance of food-borne infections.  Created: 6/14/2010 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 6/14/2010.

  15. Comparison of restriction enzymes for pulsed-field gel electrophoresis typing of Moraxella catarrhalis.

    Science.gov (United States)

    Marti, Sara; Puig, Carmen; Domenech, Arnau; Liñares, Josefina; Ardanuy, Carmen

    2013-07-01

    NotI, the most prevalent restriction enzyme used for typing Moraxella catarrhalis, failed to digest genomic DNA from respiratory samples. An improved pulsed-field gel electrophoresis (PFGE) methodology determined SpeI as the best choice for typing this bacterial species, with a good restriction of clinical samples and a good clustering correlation with NotI.

  16. Experiences in the epidemiological surveillance of foodborne pathogens by Pulsed field Gel Electophoresis (PFGE) in Peru

    OpenAIRE

    Zamudio, María Luz; Laboratorio de Referencia Nacional de Enteropatógenos, Centro Nacional de Salud Pública, Instituto Nacional de Salud, Lima, Perú. Bióloga.; Meza, Ana; Laboratorio de Referencia Nacional de Enteropatógenos, Centro Nacional de Salud Pública, Instituto Nacional de Salud, Lima, Perú. Técnico Especializado en Laboratorio.; Bailón, Henri; Laboratorio de Biotecnología y Biología Molecular, Centro Nacional de Salud Pública, Instituto Nacional de Salud, Lima, Perú. Bióloga.; Martínez-Urtaza, Jaime; Instituto de Acuicultura, Universidad de Santiago de Compostela, Santiago de Compostela, España. Doctor en Ciencias Biológicas.; Campos, Josefina; Servicio de Enterobacteria. ANLIS. Instituto “Carlos G. Malbrán”, Buenos Aires, Argentina. Bioquímica.

    2011-01-01

    Foodborne diseases and other enteric infections often occur as outbreaks and cause morbidity and mortality all over the world. In Perú, they represent a serious public health problem, and are caused by a great variety of infectious agents. For epidemiological research, a wide array of typification methods are used. One of the most important tools for the molecular subtyping of bacterial pathogens is the Pulsed Field Gel Electrophoresis (PFGE), which is a highly precise method that allows ...

  17. Molecular characterization of Clostridium tetani strains by pulsed-field gel electrophoresis and colony PCR.

    Science.gov (United States)

    Plourde-Owobi, Lucile; Seguin, Delphine; Baudin, Marie-Anne; Moste, Catherine; Rokbi, Bachra

    2005-09-01

    Pulsed-field gel electrophoresis and PCR were applied for the first time to the molecular characterization of Clostridium tetani. Among five strains tested, one (CN1339) turned out to contain a mixture of two genetically different clones and two (D11 and G761) to contain bacteria differing by the presence or absence of the 74-kb plasmid harboring the tetX gene.

  18. Trapping and breaking of in vivo nicked DNA during pulsed field gel electrophoresis.

    Science.gov (United States)

    Khan, Sharik R; Kuzminov, Andrei

    2013-12-15

    Pulsed field gel electrophoresis (PFGE) offers a high-resolution approach to quantify chromosomal fragmentation in bacteria, measured as percentage of chromosomal DNA entering the gel. The degree of separation in pulsed field gel (PFG) depends on the size of DNA as well as various conditions of electrophoresis such as electric field strength, time of electrophoresis, switch time, and buffer composition. Here we describe a new parameter, the structural integrity of the sample DNA itself, that influences its migration through PFGs. We show that subchromosomal fragments containing both spontaneous and DNA damage-induced nicks are prone to breakage during PFGE. Such breakage at single-strand interruptions results in artifactual decrease in molecular weight of linear DNA making accurate determination of the number of double-strand breaks difficult. Although breakage of nicked subchromosomal fragments is field strength independent, some high-molecular-weight subchromosomal fragments are also trapped within wells under the standard PFGE conditions. This trapping can be minimized by lowering the field strength and increasing the time of electrophoresis. We discuss how breakage of nicked DNA may be mechanistically linked to trapping. Our results suggest how to optimize conditions for PFGE when quantifying chromosomal fragmentation induced by DNA damage. Copyright © 2013 Elsevier Inc. All rights reserved.

  19. Optimization of separation and detection schemes for DNA with pulsed field slab gel and capillary electrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    McGregor, David A. [Iowa State Univ., Ames, IA (United States)

    1993-07-01

    The purpose of the Human Genome Project is outlined followed by a discussion of electrophoresis in slab gels and capillaries and its application to deoxyribonucleic acid (DNA). Techniques used to modify electroosmotic flow in capillaries are addressed. Several separation and detection schemes for DNA via gel and capillary electrophoresis are described. Emphasis is placed on the elucidation of DNA fragment size in real time and shortening separation times to approximate real time monitoring. The migration of DNA fragment bands through a slab gel can be monitored by UV absorption at 254 nm and imaged by a charge coupled device (CCD) camera. Background correction and immediate viewing of band positions to interactively change the field program in pulsed-field gel electrophoresis are possible throughout the separation. The use of absorption removes the need for staining or radioisotope labeling thereby simplifying sample preparation and reducing hazardous waste generation. This leaves the DNA in its native state and further analysis can be performed without de-staining. The optimization of several parameters considerably reduces total analysis time. DNA from 2 kb to 850 kb can be separated in 3 hours on a 7 cm gel with interactive control of the pulse time, which is 10 times faster than the use of a constant field program. The separation of ΦX174RF DNA-HaeIII fragments is studied in a 0.5% methyl cellulose polymer solution as a function of temperature and applied voltage. The migration times decreased with both increasing temperature and increasing field strength, as expected. The relative migration rates of the fragments do not change with temperature but are affected by the applied field. Conditions were established for the separation of the 271/281 bp fragments, even without the addition of intercalating agents. At 700 V/cm and 20°C, all fragments are separated in less than 4 minutes with an average plate number of 2.5 million per meter.

  20. Molecular subtyping of Clostridium botulinum by pulsed-field gel electrophoresis.

    Science.gov (United States)

    Lúquez, Carolina; Joseph, Lavin A; Maslanka, Susan E

    2015-01-01

    Pulsed-field gel electrophoresis (PFGE) has been extensively used to estimate the genetic diversity of Clostridium botulinum. In addition, PFGE is the standard method for investigating foodborne outbreaks associated with various enteric pathogens, including C. botulinum. PFGE can be used to exclude a suspected but not confirmed food source when the patterns of the food and clinical isolates are different. Indistinguishable PFGE patterns may also be useful for linking isolates between patients or to a food source, but results must be interpreted within an epidemiological context to ensure isolates are truly related. Here, we describe a standardized laboratory protocol for molecular subtyping of C. botulinum by PFGE.

  1. Genetic profiling of Klebsiella pneumoniae: comparison of pulsed field gel electrophoresis and random amplified polymorphic DNA

    Science.gov (United States)

    Ashayeri-Panah, Mitra; Eftekhar, Fereshteh; Ghamsari, Maryam Mobarak; Parvin, Mahmood; Feizabadi, Mohammad Mehdi

    2013-01-01

    In this study, the discriminatory power of pulsed field gel electrophoresis (PFGE) and random amplified polymorphic DNA (RAPD) methods for subtyping of 54 clinical isolates of Klebsiella pneumoniae were compared. All isolates were typeable by RAPD, while 3.6% of them were not typeable by PFGE. The repeatability of both typing methods were 100% with satisfying reproducibility (≥ 95%). Although the discriminatory power of PFGE was greater than RAPD, both methods showed sufficient discriminatory power (DI > 0.95) which reflects the heterogeneity among the K. pneumoniae isolates. An optimized RAPD protocol is less technically demanding and time consuming that makes it a reliable typing method and competitive with PFGE. PMID:24516423

  2. Trapping and breaking of in vivo nicked DNA during pulsed-field gel electrophoresis

    Science.gov (United States)

    Khan, Sharik R.; Kuzminov, Andrei

    2013-01-01

    Pulsed field gel electrophoresis (PFGE) offers a high-resolution approach to quantify chromosomal fragmentation in bacteria, measured as percent of chromosomal DNA entering the gel. The degree of separation in PFG depends upon the size of DNA, as well as various conditions of electrophoresis, such as electric field strength (FS), time of electrophoresis, switch time and buffer composition. Here we describe a new parameter, the structural integrity of the sample DNA itself, that influences its migration through PFGs. We show that sub-chromosomal fragments containing both spontaneous and DNA damage-induced nicks are prone to breakage during PFGE. Such breakage at single strand interruptions results in artefactual decrease in molecular weight of linear DNA making accurate determination of the number of double strand breaks difficult. While breakage of nicked sub-chromosomal fragments is FS-independent, some high molecular weight sub-chromosomal fragments are also trapped within wells under the standard PFGE conditions. This trapping can be minimized by lowering the field strength and increasing the time of electrophoresis. We discuss how breakage of nicked DNA may be mechanistically linked to trapping. Our results suggest how to optimize conditions for PFGE when quantifying chromosomal fragmentation induced by DNA damage. PMID:23770235

  3. Epidemiological Investigation of Salmonella Tilene by Pulsed-Field Gel Electrophoresis and Polymerase Chain Reaction

    Directory of Open Access Journals (Sweden)

    Chandar M Anand

    1997-01-01

    Full Text Available Pulsed-field gel electrophoresis (PFGE and DNA fingerprinting by the polymerase chain reaction (PCR were performed on 11 isolates of Salmonella tilene. Five strains were from a cluster of human patients, six from sugar gliders and pygmy hedgehogs kept as family pets or from local pet retailers, and one isolate from the first North American case of S tilene described in Washington State in 1994. The PFGE restriction patterns showed all isolates to be similar. However, PCR using primers to the 16S and 23S rRNA genes of Escherichia coli demonstrated that the Washington State isolate differed from the rest of the other isolates, which were all similar based upon their DNA fingerprint. This study indicates that reliance on one technique alone may be insufficient to show nuances between strains that are, in many respects, closely related.

  4. Genetic profiling of Klebsiella pneumoniae: comparison of pulsed field gel electrophoresis and random amplified polymorphic DNA

    Directory of Open Access Journals (Sweden)

    Mitra Ashayeri-Panah

    2013-09-01

    Full Text Available In this study, the discriminatory power of pulsed field gel electrophoresis (PFGE and random amplified polymorphic DNA (RAPD methods for subtyping of 54 clinical isolates of Klebsiella pneumoniae were compared. All isolates were typeable by RAPD, while 3.6% of them were not typeable by PFGE. The repeatability of both typing methods were 100% with satisfying reproducibility (≥ 95%. Although the discriminatory power of PFGE was greater than RAPD, both methods showed sufficient discriminatory power (DI > 0.95 which reflects the heterogeneity among the K. pneumoniae isolates. An optimized RAPD protocol is less technically demanding and time consuming that makes it a reliable typing method and competitive with PFGE.

  5. Optimization of a pulsed-field gel electrophoresis for molecular typing of Proteus mirabilis

    Directory of Open Access Journals (Sweden)

    Alper Karagöz

    2013-09-01

    Full Text Available Objective: For the detection of outbreaks caused byProteus mirabilis, strains clonal relations are determinedmethods as “pulsed-field gel electrophoresis (PFGE”.The aim of this study was optimization of a pulsed-fieldgel electrophoresis for molecular typing of P. mirabilis.Methods: In this study, PFGE’ protocol is optimized foruse in molecular typing of P. mirabilis. Phylogenetic analyzesof strains were evaluated with Bionumerics softwaresystem (version 6.01; Applied Maths, Sint-Martens-Latem, Belgium.Results: This protocol compared with Gram-negativebacteria PFGE protocols, NotI enzyme is suitable for thisbacterium. Electrophoresis conditions should be revealedas; - block 1: initial pulse duration 1 sec, ending pulseduration 30 sec, striking angle 120°, the current 6 V/cm2,temperature 14°C, time 8 hours; - block 2: initial pulseduration 30 sec, ending pulse duration 70 sec, strikingangle 120°, the current 6 V/cm2, temperature 14°C, time16 hours; - TBE, pH=8.4.Conclusion: P. mirabilis strains were typed by PFGE andBionumerics analysis program were determined clonal relationships.The procedure was simple, reproducible andsuitable for these bacteria. Also it was evaluated, becauseof reducing time, the solution volumes and enzymes canbe economically. Outbreaks of nosocomial infections dueto bacteria studied assessment and the potential to provideuseful information about the degree of prevalence.This optimized protocol is allowed different centers’ PFGEresults to compare with other laboratories results. J ClinExp Invest 2013; 4 (3: 306-312Key words: Proteus mirabilis, molecular typing, pulsedfieldgel electrophoresis.

  6. In vitro genotypic variation of Campylobacter coli documented by pulsed-field gel electrophoretic DNA profiling, implications for epidemiological studies

    DEFF Research Database (Denmark)

    On, Stephen L.W.

    1998-01-01

    Six isolates of Campylobacter coli from different pig herds were subcultured up to 50 times over a 6-month period and DNA samples suitable for pulsed-field gel electrophoretic (PFGE) profiling prepared at regular (1, 20, 40 and 50 passages) intervals. In 5/6 strains, changes in the banding patter...

  7. Genotypic characterization of Salmonella by multilocus sequence typing, pulsed-field gel electrophoresis and amplified fragment length polymorphism

    DEFF Research Database (Denmark)

    Torpdahl, Mia; Skov, Marianne N.; Sandvang, Dorthe

    2005-01-01

    subspecies enterica isolates. A total of 25 serotypes were investigated that had been isolated from humans or veterinary sources in Denmark between 1995 and 2001. All isolates were genotyped by multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE) and amplified fragment length...

  8. Genetic diversity demonstrated by pulsed field gel electrophoresis of Salmonella enterica isolates obtained from diverse sources in Mexico

    Science.gov (United States)

    This study was conducted to determine the genetic diversity of Salmonella isolates recovered from a variety of sources using pulsed-field gel electrophoresis (PFGE) to assess their possible relatedness. Salmonella was isolated from ca. 52% of samples from a pepper var. Bell production system. A to...

  9. Construction of physical and genetic maps of Chlamydia trachomatis serovar L2 by pulsed-field gel electrophoresis

    DEFF Research Database (Denmark)

    Birkelund, Svend; Stephens, RS

    1992-01-01

    We constructed the physical map of Chlamydia trachomatis serovar L2 by using three restriction endonucleases, NotI (GC[GGCCGC), SgrAI (C(A/G)[CCGG(T/G)G), and Sse8387I (CCTGCA[GG), and we analyzed the fragments by pulsed-field gel electrophoresis. A total of 25 restriction endonuclease sites and 13...

  10. Application of multiplex PCR, pulsed-field gel electrophoresis (PFGE), and BOX-PCR for molecular analysis of enterococci

    Science.gov (United States)

    The objective of the study was to use band-based molecular methods including BOX-PCR (Polymerase Chain Reaction) and Pulsed-Field Gel Electrophoresis (PFGE) to determine if genetically related enterococci were found among different stores, food types, or years. Enterococci were also characterized f...

  11. Comparative Studies on Preparation of Large Plant DNA Fragments by Pulse Field Gel Electrophoresis

    Institute of Scientific and Technical Information of China (English)

    Yang Jiliang(杨继良); Wang Qinghua(王庆华); Deng Daiyong; Yang Dianer; Jin Demin; Weng Manli; Zhang Juren; Wang Bin

    2004-01-01

    The preparation of large plant DNA fragments is extremely important to the construction of large insert DNA libraries (YAC, BAC, PAC and TAC). Although several techniques have been developed in each step of large plant DNA fragments preparation, the whole processing remains complicated and difficult. Based on authors research experience and the recent worldwide development in this field, the following aspects are discussed in this paper: techniques of plant high molecular weight (HMW) DNA purification by pre-electrophoresis, the optimal conditions for the partial digestion of the HMW DNA by HindIII, the isolation effects of of large plant DNA fragments (100~400 kb) with different parameters of pulse field gel electrophoresis (PFGE), and the recovery of large DNA fragments. Through comparative studies, the advantages and disadvantages of each technique are discussed and some recommendations are proposed for preparing high quality large plant DNA fragments. The suggested techniques have been used in preparing the large DNA fragments of maize, rice, moss, laver, sea tangle and peach,and similar results are obtained among all the materials. This paper only reports the results using maize as material.

  12. Meta-analysis of pulsed-field gel electrophoresis fingerprints based on a constructed Salmonella database.

    Directory of Open Access Journals (Sweden)

    Wen Zou

    Full Text Available A database was constructed consisting of 45,923 Salmonella pulsed-field gel electrophoresis (PFGE patterns. The patterns, randomly selected from all submissions to CDC PulseNet during 2005 to 2010, included the 20 most frequent serotypes and 12 less frequent serotypes. Meta-analysis was applied to all of the PFGE patterns in the database. In the range of 20 to 1100 kb, serotype Enteritidis averaged the fewest bands at 12 bands and Paratyphi A the most with 19, with most serotypes in the 13-15 range among the 32 serptypes. The 10 most frequent bands for each of the 32 serotypes were sorted and distinguished, and the results were in concordance with those from distance matrix and two-way hierarchical cluster analyses of the patterns in the database. The hierarchical cluster analysis divided the 32 serotypes into three major groups according to dissimilarity measures, and revealed for the first time the similarities among the PFGE patterns of serotype Saintpaul to serotypes Typhimurium, Typhimurium var. 5-, and I 4,[5],12:i:-; of serotype Hadar to serotype Infantis; and of serotype Muenchen to serotype Newport. The results of the meta-analysis indicated that the pattern similarities/dissimilarities determined the serotype discrimination of PFGE method, and that the possible PFGE markers may have utility for serotype identification. The presence of distinct, serotype specific patterns may provide useful information to aid in the distribution of serotypes in the population and potentially reduce the need for laborious analyses, such as traditional serotyping.

  13. Typing of Methicillin Resistant Staphylococcus Aureus Using DNA Fingerprints by Pulsed-field Gel Electrophoresis

    Science.gov (United States)

    Rebic, Velma; Budimir, Ana; Aljicevic, Mufida; Bektas, Sabaheta; Vranic, Sabina Mahmutovic; Rebic, Damir

    2016-01-01

    Background: Methicillin resistant Staphylococcus aureus (MRSA) is responsible for a wide spectrum of nosocomial and community associated infections worldwide. The aim of this study was to analyze MRSA strains from the general population in Canton Sarajevo, B&H. Methods: Our investigation including either phenotypic and genotypic markers such as antimicrobial resistance, pulsed-field gel electrophoresis (PFGE), SCC typing, and Panton-Valentine leukocidin (PVL) detection. Results: Antimicrobial susceptibility: all MRSA isolates were resistant to the β-lactam antibiotics tested, and all isolates were susceptible trimethoprim sulphamethoxazole, rifampicin, fusidic acid, linezolid and vancomycin. Sixty-eight per cent of the MRSA isolates were resistant to erythromycin, 5% to clindamycin, 5% to gentamicin and 4% to ciprofloxacin. After the PFGE analysis, the isolates were grouped into five similarity groups: A-E. The largest number of isolates belonged to one of two groups: C: 60 (60%) and D: 27 (27%). In both groups C and D, SCCmec type IV was predominant (60% and 88, 8%, respectively). A total of 24% of the isolates had positive expression of PVL genes, while 76% showed a statistically significantly greater negative expression of PVL genes. Conclusion: SCCmec type IV, together with the susceptibility profile and PFGE grouping, is considered to be typical of CA-MRSA PMID:27708486

  14. Molecular Typing of Acinetobacter Baumannii Clinical Strains in Tehran by Pulsed-Field Gel Electrophoresis

    Directory of Open Access Journals (Sweden)

    Neda Farahani

    2013-03-01

    Full Text Available Background & Objective : Currently, Acinetobacter baumannii is an important nosocomial pathogen insofar as its hospital outbreaks have been described from various geographical areas. Since the discrimination of strains within a species is important for delineating nosocomial outbreaks, this study was conducted with the aim of genotyping the A. baumannii clinical strains in Tehran via the pulsed-field gel electrophoresis (PFGE method, which is the most accurate method used for the typing of bacterial species.   Materials & methods: This study was performed on 70 isolates of acinetobacter baumannii isolated from patients from Baqiyatallah, Rasoole Akram, and Milad hospitals in Tehran. Cultural and biochemical methods were used for the identification of the isolates in species level, and then susceptibility tests were carried out on 50 isolates of A. baumannii using the disk diffusion method. The PFGE method was performed on the isolates by Apa I restriction enzyme. Finally, the results of the PFGE were analyzed. Result: Acinetobacter baumannii strains isolated from hospitals in Tehran showed seven different genetic patterns, two of which were sporadic . Also, genotypic profiles were different in each hospital, and different patterns of genetic resistance to common antibiotics were observed. Conclusion: A lthough diversity was observed among the strains of A. baumannii by the PFGE method in Tehran, no epidemic strains were found among them.  

  15. The limitations of pulsed-field gel electrophoresis for analysis of Yersinia enterocolitica isolates.

    Science.gov (United States)

    Gilpin, B J; Robson, B; Lin, S; Hudson, J A; Weaver, L; Dufour, M; Strydom, H

    2014-09-01

    This study describes the analysis of 432 isolates of Yersinia enterocolitica by pulsed-field gel electrophoresis (PFGE). PFGE had a high level of discrimination with biotype 1A isolates (Simpson's Diversity Index 0.997), but with the clinically important biotypes 2, 3 and 4, the discriminatory ability of PFGE was so low as to severely limit its usefulness (DI <0.6). For biotypes 2, 3 and 4, 79% or more of isolates of each biotype were of just three different PFGE profiles. Because of this, four known outbreaks of yersiniosis would not have been identified by PFGE analysis. However, a previously unrecognized potential outbreak of yersiniosis caused by biotype 4 isolates was identified on the basis of a rare PFGE genotype with spatial and temporal clustering. We conclude that PFGE has a very limited application to the genotyping of Y. enterocolitica biotypes 2, 3 and 4, and inferences based on finding indistinguishable PFGE profiles among cases or between cases and sources need to be substantiated using alternative typing tools, or strong epidemiological evidence.

  16. Molecular Analysis of Mycobacterium avium Isolates by Using Pulsed-Field Gel Electrophoresis and PCR

    Science.gov (United States)

    Pestel-Caron, Martine; Graff, Gabriel; Berthelot, Gilles; Pons, Jean-Louis; Lemeland, Jean-François

    1999-01-01

    Genetic relationships among 46 isolates of Mycobacterium avium recovered from 37 patients in a 2,500-bed hospital from 1993 to 1998 were assessed by pulsed-field gel electrophoresis (PFGE) and PCR amplification of genomic sequences located between the repetitive elements IS1245 and IS1311. Each technique enabled the identification of 27 to 32 different patterns among the 46 isolates, confirming that the genetic heterogeneity of M. avium strains is high in a given community. Furthermore, this retrospective analysis of sporadic isolates allowed us (i) to suggest the existence of two remanent strains in our region, (ii) to raise the question of the possibility of nosocomial acquisition of M. avium strains, and (iii) to document laboratory contamination. The methods applied in the present study were found to be useful for the typing of M. avium isolates. In general, both methods yielded similar results for both related and unrelated isolates. However, the isolates in five of the six PCR clusters were distributed among two to three PFGE patterns, suggesting that this PCR-based method may have limitations for the analysis of strains with low insertion sequence copy numbers or for resolution of extended epidemiologic relationships. PMID:10405383

  17. Characterization of Erwinia amylovora strains from Bulgaria by pulsed-field gel electrophoresis.

    Science.gov (United States)

    Atanasova, Iliana; Urshev, Zoltan; Hristova, Petya; Bogatzevska, Nevena; Moncheva, Penka

    2012-01-01

    The aim of this study was to characterize genetically Bulgarian Erwinia amylovora strains using pulsed-field gel electrophoresis (PFGE) analysis. Fifty E. amylovora strains isolated from different hosts, locations, as well as in different years were analysed by PFGE after XbaI, SpeI, and XhoI digestion of the genomic DNA. The strains were distributed into four groups according to their XbaI-generated profile. About 82% of the strains displayed a PFGE profile identical to that of type Pt2. Three strains belonged to the Central Europe Pt1 type. Two new PFGE profiles, not reported so far, were established--one for a strain isolated from Malus domestica and another for all Fragaria spp. strains. The same grouping of the strains was obtained after analysis of the SpeI digestion patterns. On the basis of PFGE profiles, after XbaI and SpeI digestion, a genetic differentiation between the strains associated with subfamily Maloideae and subfamily Rosoideae was revealed. The presence of more than one PFGE profile in the population of E. amylovora in Bulgaria suggests a multiple source of inoculum.

  18. Rapid pulsed-field gel electrophoresis protocol for Legionella pneumophila typing

    Directory of Open Access Journals (Sweden)

    Massimiliano Orsini

    2008-06-01

    Full Text Available

    Background: Genomic DNA patterns generated by pulsed-field gel electrophoresis (PGFE are highly specific for different strains of an organism and have significant value in epidemiologic investigations of infectious disease outbreaks. A disadvantage of PFGE is that the procedure requires up to 6 days to complete.

    Methods: We developed a rapid PFGE protocol for subtyping Legionella pneumophila isolates based on the standardized protocol currently used. Various combinations of reaction conditions (e.g., lysis time and temperature, restriction enzyme concentration and electrophoresis parameters were applied to devise a simple and rapid PFGE protocol that could also be used for frozen bacteria.

    Results: PFGE analysis of Legionella pneumophila isolates can be completed in 26 hours using this protocol compared to 6 days for the conventional one.

    Conclusions: We successfully applied a rapid PFGE protocol for Legionella pneumophila typing and comparison of the patterns obtained from the rapid compared with the conventional method showed that the rapid protocol gave identical and highly reproducible results.

  19. Optimization of Pulse-Field Gel Electrophoresis for Subtyping of Klebsiella pneumoniae

    Directory of Open Access Journals (Sweden)

    Kongxin Hu

    2013-07-01

    Full Text Available A total of 110 strains of Klebsiella pneumoniae were used to optimize pulsed-field gel electrophoresis (PFGE for subtyping of K. pneumoniae. For optimization of electrophoresis parameters (EPs of XbaI-PFGE, 11 isolates were analyzed with XbaI digestion using three EPs. The EP of a switch time of 6 to 36 s for 18.5 h gave clearest patterns and was declared the optimal EP for XbaI PFGE of K. pneumoniae. By software analysis and pilot study, AvrII was chosen as another PFGE enzyme. Both XbaI- and AvrII-PFGE gave D-values higher than 0.99 for 69 K. pneumoniae isolated from different sources. Our results also showed good typeability, reproducibility of both XbaI- and AvrII-PFGE for K. pneumoniae subtyping. Furthermore, the established PFGE method also had good discriminatory power to distinguish outbreak K. pneumoniae strains and a high degree of consistency with multilocus sequence typing method. A rapid PFGE protocol was established here, which could be used for genotyping and other researches of K. pneumoniae.

  20. Suitability of PCR fingerprinting, infrequent-restriction-site PCR, and pulsed-field gel electrophoresis, combined with computerized gel analysis, in library typing of Salmonella enterica serovar enteritidis

    DEFF Research Database (Denmark)

    Garaizar, J.; Lopez-Molina, N.; Laconcha, I.

    2000-01-01

    Strains of Salmonella enterica (n = 212) of different serovars and phage types were used to establish a library typing computerized system for serovar Enteritidis on the basis of PCR fingerprinting, infrequent-restriction-site PCR (IRS-PCR), or pulsed-field gel electrophoresis (PFGE). The rate...... showed an intercenter reproducibility value of 93.3%. The high reproducibility of PFGE combined with the previously determined high discrimination directed its use for library typing. The use of PFGE with enzymes XbaI, BlnI, and SpeI for library typing of serovar Enteritidis was assessed with GelCompar 4...

  1. First clinical isolates of Cronobacter spp. (Enterobacter sakazakii) in Argentina: characterization and subtyping by pulsed-field gel electrophoresis.

    Science.gov (United States)

    Asato, Valeria C; Vilches, Viviana E; Pineda, María G; Casanueva, Enrique; Cane, Alejandro; Moroni, Mirian P; Brengi, Silvina P; Pichel, Mariana G

    2013-01-01

    Cronobacter species are opportunistic pathogens associated with severe infections in neonates and immunocompromised infants. From January 2009 through September 2010, two cases of neonatal infections associated with Cronobacter malonaticus and one case associated with Cronobacter sakazakii, two of them fatal, were reported in the same hospital. These are the first clinical isolates of Cronobacter spp. in Argentina. The objective of this work was to characterize and subtype clinical isolates of Cronobacter spp. in neonate patients, as well as to establish the genetic relationship between these isolates and the foodborne isolates previously identified in the country. Pulsed-field gel electrophoresis analysis showed a genetic relationship between the C. malonaticus isolates from two patients. Different results were found when the pulsed-field gel electrophoresis patterns of clinical isolates were compared with those deposited in the National Database of Cronobacter spp.

  2. Clonal evolution multi-drug resistant Acinetobacter baumannii by pulsed-field gel electrophoresis

    Directory of Open Access Journals (Sweden)

    P Mohajeri

    2015-01-01

    Full Text Available Background: Acinetobacter baumannii is usually multi-drug resistant (MDR, including third generation cephalosporins, amino glycosides and fluoroquinolone. Resistance to these antibiotics is mediated by multiple factors such as: lactamases, efflux pumps and other mechanisms of resistance. Pulsed-field gel electrophoresis (PFGE was then used to investigate the genetic relationships among the MDR isolates. Aim: The aim of this study was to determine MDR isolates and the existence of OXAs genes among MDR isolates of A. baumannii collected from Kermanshah hospitals in west of Iran. Materials and Methods: Forty-two MDR A. baumannii were collected from patients at Kermanshah hospitals. The isolates were identified by biochemical tests and API 20NE kit. The susceptibility to different antibiotics by disk diffusion method was determined. Polymerase chain reaction (PCR was performed for detection of blaOXA-23-like , blaOXA-24-like , blaOXA-51-like and blaOXA-58-like betalactamase genes in isolates and clonal relatedness was done by PFGE (with the restriction enzyme ApaI and patterns analyzed by Bionumeric software. Results: This study showed high resistant to ciprofloxacin, piperacillin, ceftazidime and also resistant to other anti-microbial agents and more spread blaOXA-23-like gene (93% in MDR isolate. The PFGE method obtained six clones: A (10, B (9, C (5, D (4, E (11 and F (3 that clone E was outbreak and dominant in different wards of hospitals studied. Conclusion: An isolate from the emergency ward of these hospitals had indistinguishable isolates PFGE profile and similar resistance profile to isolates from intensive care unit (ICU, suggesting likely transmission from ICU to emergency via patient or hospital staff contact.

  3. Fluorescence amplified fragment length polymorphism compared to pulsed field gel electrophoresis for Listeria monocytogenes subtyping

    Directory of Open Access Journals (Sweden)

    Roussel Sophie

    2013-01-01

    Full Text Available Abstract Background Listeriosis is a severe infection which mainly affects pregnant women, neonates and immuno-compromised adults. ANSES’s Laboratory for Food safety has been the European Union Reference Laboratory (EURL for L. monocytogenes in the food chain since 2006. Pulsed Field Gel Electrophoresis (PFGE is routinely used in the EURL for the surveillance of L. monocytogenes isolated from foods, animals and the environment. One of the main EURL activities is to evaluate alternative molecular subtyping methods to PFGE, and integrate their use within the National Reference Laboratories (NRL network. Since 2008, the United Kingdom (UK-NRL for L. monocytogenes at the Health Protection Agency (HPA, London, has used fluorescent Amplified Fragment Length Polymorphism (fAFLP for the routine surveillance of L. monocytogenes isolated from human clinical cases, food and food processing environments in the UK. This study compares fAFLP with PFGE for subtyping L. monocytogenes. Results A panel of 109 L. monocytogenes isolates from either human cases of listeriosis, foods, food processing environments and animals were used for the comparative evaluation. Among these, 2 strains were tested from duplicate culture by both methods. The panel also included field isolates, isolates associated with outbreaks or sporadic cases and reference strains. The two strains tested in duplicate displayed the same fAFLP and PFGE types. Strains known to be epidemiologically associated with one another were found to have unique PFGE and fAFLP types. FAFLP and PFGE divided the strains into 76 and 82 distinct profiles, or types, respectively. The discriminatory index calculated was 0.993 and 0.996 for fAFLP and PFGE, respectively. Conclusions The discriminatory ability of fAFLP was similar to that of PFGE for the subtyping of L. monocytogenes isolates. As a less labour intensive technique fAFLP may be a better method to use than PFGE in investigating outbreaks of human

  4. Assessment of resolution and intercenter reproducibility of results of genotyping Staphylococcus aureus by pulsed-field gel electrophoresis of SmaI macrorestriction fragments: a multicenter study

    NARCIS (Netherlands)

    A.F. van Belkum (Alex); S. Salmenlinna; M. Kooistra; B. Cookson (Barry); W. Witte; N. El Solh; F. Forey; J. Etienne (Jerome); R. Goering; A. Morvan; M. Struelens; J. Vuopio-Varkila; F.C. Tenover (Fred); C. Steward; N. Legakis; A. Talens; F. O'Brien (Frances); P. Tassios; R. de Ryck; W. Grubb; M.E. Kaufmann; H.A. Verbrugh (Henri); W.B. van Leeuwen (Willem)

    1998-01-01

    textabstractTwenty well-characterized isolates of methicillin-resistant Staphylococcus aureus were used to study the optimal resolution and interlaboratory reproducibility of pulsed-field gel electrophoresis (PFGE) of DNA macrorestriction fragments. Five identical

  5. Comparative typing of Pseudomonas aeruginosa by random amplification of polymorphic DNA or pulsed-field gel electrophoresis of DNA macrorestriction fragments

    NARCIS (Netherlands)

    N. Renders (Nicole); Y. Romling; A.F. van Belkum (Alex); H.A. Verbrugh (Henri)

    1996-01-01

    textabstractEighty-seven strains of Pseudomonas aeruginosa were typed by random amplification of polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE) of macrorestriction fragments. Stains were clustered on the basis of interpretative criteria as presented

  6. Comparative typing of Pseudomonas aeruginosa by random amplification of polymorphic DNA or pulsed-field gel electrophoresis of DNA macrorestriction fragments

    NARCIS (Netherlands)

    N. Renders (Nicole); Y. Romling; A.F. van Belkum (Alex); H.A. Verbrugh (Henri)

    1996-01-01

    textabstractEighty-seven strains of Pseudomonas aeruginosa were typed by random amplification of polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE) of macrorestriction fragments. Stains were clustered on the basis of interpretative criteria as presented

  7. Physical and genetic mapping of the genomes of five Mycoplasma hominis strains by pulsed-field gel electrophoresis

    DEFF Research Database (Denmark)

    Ladefoged, Søren; Christiansen, Gunna

    1992-01-01

    We present the complete maps of five Mycoplasma hominis genomes, including a detailed restriction map and the locations of a number of genetic loci. The restriction fragments were resolved by field inversion gel electrophoresis or by the contour-clamped homogeneous-electric-field system of pulsed...... was inverted. The numbers and order of mapped restriction sites were only partly conserved, and this conservation was restricted to certain regions. The gene order was compared with the gene order established for other bacteria and was found to be identical to that of the phylogenetically related Clostridium...

  8. The association of serotype and pulsed-field gel electrophoresis genotype in isolates of Streptococcus pneumoniae isolated in Israel

    Directory of Open Access Journals (Sweden)

    M. Bar-Meir

    2015-05-01

    Full Text Available The relationship between Streptococcus pneumoniae isolates causing invasive infections in children admitted to a single center in central Israel was examined by pulsed-field gel electrophoresis (PFGE and serotyping. Although there was a close correlation between serotype and PFGE clone, the genetic diversity varied by serotype, with some genotypes comprising multiple serotypes. Additionally, clones C and D were associated with higher penicillin minimum inhibitory concentrations. Serotyping alone may be insufficient for epidemiological mapping of pneumococcal isolates in the era of pneumococcal conjugate polysaccharide vaccines.

  9. One-day pulsed-field gel electrophoresis protocol for rapid determination of emetic Bacillus cereus isolates.

    Science.gov (United States)

    Kaminska, Paulina S; Fiedoruk, Krzysztof; Jankowska, Dominika; Mahillon, Jacques; Nowosad, Karol; Drewicka, Ewa; Zambrzycka, Monika; Swiecicka, Izabela

    2015-04-01

    Bacillus cereus, the Gram-positive and spore-forming ubiquitous bacterium, may cause emesis as the result of food intoxication with cereulide, a heat-stable emetic toxin. Rapid determination of cereulide-positive B. cereus isolates is of highest importance due to consequences of this intoxication for human health and life. Here we present a 1-day pulsed-field gel electrophoresis for emetic B. cereus isolates, which allows rapid and efficient determination of their genomic relatedness and helps determining the source of intoxication in case of outbreaks caused by these bacilli.

  10. Construction of physical and genetic maps of Chlamydia trachomatis serovar L2 by pulsed-field gel electrophoresis

    DEFF Research Database (Denmark)

    Birkelund, Svend; Stephens, RS

    1992-01-01

    We constructed the physical map of Chlamydia trachomatis serovar L2 by using three restriction endonucleases, NotI (GC[GGCCGC), SgrAI (C(A/G)[CCGG(T/G)G), and Sse8387I (CCTGCA[GG), and we analyzed the fragments by pulsed-field gel electrophoresis. A total of 25 restriction endonuclease sites and 13...... genes and/or operons were located on the map. The genome size was determined to be 1,045 kb. Neither highly transcribed chlamydia genes nor developmental cycle-specific genes were clustered on the genome....

  11. Pulsed field gel electrophoresis identifies an outbreak of Salmonella enterica serotype Montevideo infection associated with a supermarket hot food outlet.

    Science.gov (United States)

    Threlfall, E J; Hampton, M D; Ward, L R; Richardson, I R; Lanser, S; Greener, T

    1999-09-01

    In February 1996 Salmonella enterica serotype Montevideo infection in a patient in the North Tyneside area was attributed to consumption of cooked chicken bought from a supermarket hot food outlet. Isolates from the patient, leftover food, and environmental samples were indistinguishable by pulsed field gel electrophoresis (PFGE). PFGE also demonstrated that an outbreak of infection with S. Montevideo associated with the hot food outlet had occurred in late 1995 and early 1996. This study shows the importance of microbial strain discrimination in outbreak investigations and illustrates the value of close liaison between microbiologists, epidemiologists, and environmental health officers in the control of salmonella outbreaks.

  12. Re-evaluation, optimization, and multilaboratory validation of the PulseNet-standardized pulsed-field gel electrophoresis protocol for Listeria monocytogenes.

    Science.gov (United States)

    Halpin, Jessica L; Garrett, Nancy M; Ribot, Efrain M; Graves, Lewis M; Cooper, Kara L

    2010-03-01

    The PulseNet Methods Development and Validation Laboratory began a re-evaluation of the standardized pulsed-field gel electrophoresis (PFGE) protocols with the goal of optimizing their overall performance and robustness. Herein, we describe a stepwise evaluation of the PulseNet-standardized PFGE protocol for Listeria monocytogenes that led to the modification of several steps which significantly improved the overall appearance and reproducibility of the resulting PFGE data. These improvements included the following: (1) reducing the cell suspension concentration, (2) increasing lysozyme incubation temperature from 37 degrees C to 56 degrees C, and (3) decreasing the number of units of restriction enzymes AscI and ApaI. These changes were incorporated into a proposed protocol that was evaluated by 16 PulseNet participating laboratories, including 2 international participants. Results from the validation study indicated that the updated L. monocytogenes protocol is more robust than the original PulseNet-standardized protocol established in 1998 and this resulted in the official adoption of the new protocol into the PulseNet system in the spring of 2008. The modifications not only represent an improvement to the protocol but also describe procedural improvements that could be potentially applied to the PFGE analysis of other Gram-positive organisms.

  13. Characterization of multidrug-resistant Escherichia coli by antimicrobial resistance profiles, plasmid replicon typing, and pulsed-field gel electrophoresis.

    Science.gov (United States)

    Lindsey, Rebecca L; Frye, Jonathan G; Thitaram, Sutawee N; Meinersmann, Richard J; Fedorka-Cray, Paula J; Englen, Mark D

    2011-06-01

    The objective of this study was to examine the distribution of multidrug resistance in Escherichia coli in relation to plasmid replicon types, animal sources, and genotypes. E. coli isolates (n = 35) from seven different animal sources were selected and tested for susceptibility to 15 antimicrobials; pulsed-field gel electrophoresis was used to determine genetic relationships among the E. coli isolates. Plasmid types based on their incompatibility (Inc) replicon types were determined, and linkage disequilibrium analysis was performed for antimicrobial resistance profiles, replicon types, and animal source. A high degree of genotypic diversity was observed: 34 different pulsed-field gel electrophoresis types among the 35 isolates examined. Twelve different plasmid Inc types were detected, and all isolates carried at least one replicon type. IncF (n = 25; 71.4%) and IncFIB (n = 19; 54.3%) were the most common replicon types identified. Chloramphenicol resistance was significantly linked with four Inc types (A/C, FIIA, F, and Y), and amoxicillin/clavulanic acid was linked with three Inc types (B/O, P and Y). Resistance to any other antimicrobial was linked to two or fewer replicon types. The isolate source was linked with resistance to seven antimicrobials and IncI1. We conclude that commensal E. coli from animal sources are highly variable genotypically and are reservoirs of a diverse array of plasmids carrying antimicrobial resistance.

  14. Time-based distribution of Staphylococcus saprophyticus pulsed field gel-electrophoresis clusters in community-acquired urinary tract infections

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    Viviane Santos de Sousa

    2013-02-01

    Full Text Available The epidemiology of urinary tract infections (UTI by Staphylococcus saprophyticus has not been fully characterised and strain typing methods have not been validated for this agent. To evaluate whether epidemiological relationships exist between clusters of pulsed field gel-electrophoresis (PFGE genotypes of S. saprophyticus from community-acquired UTI, a cross-sectional surveillance study was conducted in the city of Rio de Janeiro, Brazil. In total, 32 (16% female patients attending two walk-in clinics were culture-positive for S. saprophyticus. Five PFGE clusters were defined and evaluated against epidemiological data. The PFGE clusters were grouped in time, suggesting the existence of community point sources of S. saprophyticus. From these point sources, S. saprophyticus strains may spread among individuals.

  15. Changes in Predominance of Pulsed-Field Gel Electrophoresis Profiles of Bordetella pertussis Isolates, United States, 2000-2012.

    Science.gov (United States)

    Cassiday, Pamela K; Skoff, Tami H; Jawahir, Selina; Tondella, M Lucia

    2016-03-01

    To clarify the characteristics of circulating Bordetella pertussis isolates, we used pulsed-field gel electrophoresis (PFGE) to analyze 5,262 isolates collected in the United States during 2000-2012. We found 199 PFGE profiles; 5 profiles accounted for 72% of isolates. The most common profile, CDC013, accounted for 35%-46% of isolates tested from 2000-2009; however, the proportion of isolates of this profile rapidly decreased in 2010. Profile CDC237, first seen in 2009, increased rapidly and accounted for 29% of 2012 isolates. No location bias was observed among profiles during 2000-2010, but differences were observed among isolates from different states during 2012. Predominant profiles match those observed in recent European PFGE studies. PFGE profile changes are concurrent with other recent molecular changes in B. pertussis and may be contributing to the reemergence of pertussis in the United States. Continued PFGE monitoring is critical for understanding the changing epidemiology of pertussis.

  16. Time-based distribution of Staphylococcus saprophyticus pulsed field gel-electrophoresis clusters in community-acquired urinary tract infections.

    Science.gov (United States)

    Sousa, Viviane Santos de; Rabello, Renata Fernandes; Dias, Rubens Clayton da Silva; Martins, Ianick Souto; Santos, Luisa Barbosa Gomes da Silva dos; Alves, Elisabeth Mendes; Riley, Lee Woodford; Moreira, Beatriz Meurer

    2013-02-01

    The epidemiology of urinary tract infections (UTI) by Staphylococcus saprophyticus has not been fully characterised and strain typing methods have not been validated for this agent. To evaluate whether epidemiological relationships exist between clusters of pulsed field gel-electrophoresis (PFGE) genotypes of S. saprophyticus from community-acquired UTI, a cross-sectional surveillance study was conducted in the city of Rio de Janeiro, Brazil. In total, 32 (16%) female patients attending two walk-in clinics were culture-positive for S. saprophyticus. Five PFGE clusters were defined and evaluated against epidemiological data. The PFGE clusters were grouped in time, suggesting the existence of community point sources of S. saprophyticus. From these point sources, S. saprophyticus strains may spread among individuals.

  17. Genetic diversity of Xanthomonas axonopodis pv. citri based on plasmid profile and pulsed field gel electrophoresis

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    Carvalho Flávia Maria de Souza

    2005-01-01

    Full Text Available Xanthomonas axonopodis pv. citri strains that cause disease in citrus were investigated by pulsed field and plasmid profile analysis. For the first method, genomic DNA was digested by the rare-cutting enzymes Xba I and Vsp I. The strains evaluated were collected in seven different States of Brazil and in Argentina, Bolivia, Paraguay and Uruguay. Genetic variability was found among strains of X. axonopodis pv. citri from different geographical areas Argentina, Bolivia and Uruguay, with similarities varying from 0.62 to 0.83. However, the strains collected in Brazil, despite being from different States, have shown a genetic similarity ranging from 0.83 to 1.00. Cluster analysis showed a relationship between genomic similarity and geographical origin of the strains. Plasmids were observed in all strains, with a total of five different plasmids, with sizes between 57.7 and 83.0 kilobases. The 72.6 kb plasmid was the most frequent, present in 15 out of 22 strains, while the 68.1 kb plasmid was observed in two strains only. Although the plasmid diversity detected in the present study was not very great, the X. axonopodis pv. citri strains evaluated showed a considerable degree of diversity with regard to this extrachromosomal genetic element.

  18. Identification of Burkholderia cepacia in patients with cystic fibrosis by pulsed-field gel electrophoresis

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    Mohammad Mehdi Soltan Dallal

    2014-05-01

    Conclusion: Application of PFGE and identification of pulse-type is a potential tool to enhance the investigation of apparent nosocomial outbreaks of B.cepacia. Similar type of pulse patterns was observed in this study means that all of infection has been from one source; therefore the hypothesis of transferring person to person will be rejected. Base on these results environmental sources sampling should be considered in future investigation.

  19. Characterization of vancomycin-resistant and vancomycin-susceptible Enterococcus faecium isolates from humans, chickens and pigs by RiboPrinting and pulsed-field gel electrophoresis

    DEFF Research Database (Denmark)

    Hammerum, Anette Marie; Fussing, Vivian; Aarestrup, Frank Møller;

    2000-01-01

    Forty-eight vancomycin-resistant and 35 vancomycin-sensitive Danish Enterococcus faecium isolates obtained from pigs, chickens and humans, as well as the human vanA reference isolate BM4147, were characterized by EcoRI RiboPrinting and Smal pulsed-field gel electrophoresis. RiboPrinting of the 84...

  20. Characterization of Mycoplasma hyosynoviae strains by amplified fragment length polymorphism analysis, pulsed-field gel electrophoresis and 16S ribosomal DNA sequencing

    DEFF Research Database (Denmark)

    Kokotovic, Branko; Friis, N.F.; Ahrens, Peter

    2002-01-01

    , were investigated by analysis of amplified fragment length polymorphisms of the Bgl II and Mfe I restriction sites and by pulsed-field gel electrophoresis of a Bss HII digest of chromosomal DNA. Both methods allowed unambiguous differentiation of the analysed strains and showed similar discriminatory...

  1. A comparison of BOX-PCR and pulsed-field gel electrophoresis to determine genetic relatedness of enterococci from different environments

    Science.gov (United States)

    Aims: The genetic relatedness of enterococci from poultry litter to enterococci from nearby surface water and groundwater in the Lower Fraser Valley regions of British Columbia, Canada was determined. Methods and Results: BOX-PCR and Pulsed-Field Gel Electrophoresis (PFGE) were used to subtype en...

  2. Characterization of vancomycin-resistant and vancomycin-susceptible Enterococcus faecium isolates from humans, chickens and pigs by RiboPrinting and pulsed-field gel electrophoresis

    DEFF Research Database (Denmark)

    Hammerum, Anette Marie; Fussing, Vivian; Aarestrup, Frank Møller

    2000-01-01

    Forty-eight vancomycin-resistant and 35 vancomycin-sensitive Danish Enterococcus faecium isolates obtained from pigs, chickens and humans, as well as the human vanA reference isolate BM4147, were characterized by EcoRI RiboPrinting and Smal pulsed-field gel electrophoresis. RiboPrinting of the 84...

  3. A comparison of non-typhoidal Salmonella from humans and food animals using pulsed-field gel electrophoresis and antimicrobial susceptibility patterns

    Science.gov (United States)

    Salmonellosis is one of the most important foodborne diseases affecting humans. To characterize the relationship between Salmonella causing human infections and their food animal reservoirs, we compared pulsed-field gel electrophoresis (PFGE) and antimicrobial susceptibility patterns of non-typhoida...

  4. Feasibility of measuring radiation-induced DNA double strand breaks and their repair by pulsed field gel electrophoresis in freshly isolated cells from the mouse RIF-1 tumor

    NARCIS (Netherlands)

    vanWaarde, MAWH; vanAssen, AJ; Konings, AWT; Kampinga, HH

    1996-01-01

    Purpose: To examine the technical feasibility of pulsed field gel electrophoresis (PFGE) as a predictive assay for the radioresponsiveness of tumors. Induction and repair of DNA double strand breaks (DSBs) in a freshly prepared cell suspension from a RIF-1 tumor (irradiated ex vivo) was compared

  5. Caracterização de cepas de referência de Leptospira sp utilizando a técnica de pulsed field gel electrophoresis Characterization of Leptospira sp reference strains using the pulsed field gel electrophoresis technique

    Directory of Open Access Journals (Sweden)

    Lívia Machry

    2010-04-01

    Full Text Available INTRODUÇÃO: A leptospirose é uma zoonose endêmica, mundialmente distribuída, causada por bactérias do gênero Leptospira. Este gênero compreende espécies patogênicas e saprofíticas, com mais de 200 sorovares distintos, dificultando sua caracterização. A técnica de pulsed field gel electrophoresis tem sido empregada como uma ferramenta para auxiliar nesta caracterização. Os objetivos deste trabalho foram padronizar a técnica de PFGE, determinar os perfis moleculares das cepas de referência utilizadas pelo Laboratório de Referência Nacional para Leptospirose/Centro Colaborador da Organização Mundial de Saúde para Leptospirose e criar um banco de dados com estes perfis. MÉTODOS: Foram analisadas, por PFGE, dezenove cepas utilizando a enzima de restrição NotI. RESULTADOS: Cada cepa apresentou um perfil único que pode ser considerado como uma identidade genômica específica, com exceção dos sorovares Icterohaemorrhagiae e Copenhageni, cujos perfis foram indistinguíveis. CONCLUSÕES: Dessa forma, foi possível a criação de um banco de perfis moleculares que está sendo utilizado no Laboratório para a comparação e identificação de cepas isoladas de quadros clínicos.INTRODUCTION: Leptospirosis is an endemic zoonosis of worldwide distribution, caused by bacteria of the genus Leptospira. This genus includes pathogenic and saprophytic species, with more than 200 different serovars, thus making it difficult to characterize. The technique of pulsed field gel electrophoresis has been used as a tool to aid in this characterization. The aims of this study were to standardize the PFGE technique, determine the molecular profiles of reference strains used at the National Reference Laboratory for Leptospirosis/World Health Organization Collaborating Center for Leptospirosis and create a database with these profiles. METHODS: Nineteen strains were analyzed by means of PFGE, using the restriction enzyme NotI. RESULTS: Each strain

  6. Structural analysis of mitochondrial DNA molecules from fungi and plants using moving pictures and pulsed-field gel electrophoresis.

    Science.gov (United States)

    Bendich, A J

    1996-02-02

    The size and structure of mitochondrial DNA (mtDNA) molecules was investigated by conventional and pulsed-field gel electrophoresis (PFGE) and by analyzing moving pictures during electrophoresis of individual fluorescently labelled mtDNA molecules. Little or no mtDNA that migrated into the gel was found in circular form for fungi (Schizosaccharomyces pombe, Saccharomyces cerevisiae and Neurospora crassa) or plants (Brassica hirta, tobacco, voodoo lily and maize). Most mtDNA migrated as a smear of linear DNA sizes from about 50 to 100 or 250 kilobases (kb), depending on the species, irrespective of the size of the mitochondrial genome over a range of 0.06 to 570 kb. S. cerevisiae, B. hirta and tobacco also yielded a linear mtDNA fraction containing molecules > 1000 kb in size. About half the mtDNA remained in the well of the gel after PFGE. Moving pictures revealed that this well-bound (wb) mtDNA contained molecules larger than the genome size in linear form for all species (except N. crassa) and in multi-fibered, comet-like forms for most of the wb mtDNA of N. crassa and Sc. pombe. A minor amount of the wb mtDNA with visually interpretable structure was circular: circle sizes were both larger and smaller than the 80-kb genome of S. cerevisiae, larger than the 19-kb genome of Sc. pombe and smaller than the 208-kb and 570-kb genomes of B. hirta and maize, respectively. About 25 to 75% of the wb mtDNA from cultured tobacco cells was found in circles smaller than its genome size. Partial digestion of Sc. pombe mtDNA with restriction endonucleases that cleave once per genome revealed gel bands at about 38 kb and 19 kb with a smear of sizes between the bands and below the 19-kb band, suggesting a head-to-tail genomic concatemer as the most prominent form in extracted mtDNA. A pattern of bands with smears was also found for complete digests (with multiply cleaving enzymes) of mtDNA from Sc. pombe, S. cerevisiae and N. crassa, but bands without smears were found for

  7. Heterogeneity of Campylobacter species isolated from serial stool specimens of Egyptian children using pulsed field gel electrophoresis

    Directory of Open Access Journals (Sweden)

    Atef M. El-Gendy

    2013-03-01

    Full Text Available Background: The genus Campylobacter spp. is a common cause of human acute bacteria lenteritis and travellers’ diarrhoea worldwide.Objective: To determine whether multiple serial isolations of Campylobacter spp., when obtained from a single child, represented the same or a different organism.Methods: In a birth cohort study conducted in Egypt, numerous children showed serial isolations of Campylobacter spp. Of these, 13 children were selected from different households based on the successive isolation of six or more Campylobacter isolates from stool samples.Results: Eighty isolates were recovered and identified as either Campylobacter coli (n = 25 or Campylobacter jejuni (n = 55. Pulsed-field gel electrophoresis (PFGE revealed the presence of 38 unique C. jejuni and 24 C. coli profiles at a similarity level of ≥ 90%. Although no seriallyidentical isolates were detected in six children, others demonstrated at least one identical couple of isolates; all identified serially between one to six weeks. Two children demonstrated > 80% similar couples of isolates that appeared seven months apart. PFGE could be a useful tool for differentiating reinfection, relapse and convalescent excretion phases.Conclusion: Our data suggest that Campylobacter infection in children is a complex process; children are exposed to multiple species in endemic environments and strains of the same bacterium appear to be shed serially between one to six weeks after the first exposure. Isolates that persisted for longer periods were relatively less similar, as shown from the results of this study.

  8. Isolation of Listeria monocytogenes in a salami producing plant in Piedmont: use of pulsed field gel electrophoresis to trace contaminations

    Directory of Open Access Journals (Sweden)

    Annalisa Costa

    2013-06-01

    Full Text Available The ability of Listeria monocytogenes to survive in different environments and establish persistent contaminations is an important issue for food producers. This study aimed to assess the environmental contamination level in an Italian salami producing plant and to identify possible sources of contamination using pulsed field gel electrophoresis (PFGE on L. monocytogenes isolates obtained from environmental (n=54 and meat samples (n=9 collected over 9 months. Detection of L. monocytogenes was performed using the UNI EN ISO 11290-1 procedure and every isolate was characterised with PFGE, using AscI and ApaI restriction enzymes. The environmental detection frequencies were constant both in the first (22% and the second (27% visit, thus suggesting the presence of strains adapted to the processing plant. Equipments can represent a reservoir of L. monocytogenes from which it can spread into the whole producing plant. The reservoir was documented by PFGE results which showed several persistent strains. Moreover, PFGE proved the cross-contamination between surfaces and semiprocessed products like pastes, which furthermore have been contaminated by L. monocytogenes in 100% of samples in the first two visits and in 33% in the last visit. This study gave evidence that detection methods and PFGE characterisation can be effective tools to detect possible sources and routes of contamination.

  9. Diversity of pulsed-field gel electrophoresis patterns of cereulide-producing isolates of Bacillus cereus and Bacillus weihenstephanensis.

    Science.gov (United States)

    Castiaux, Virginie; N'guessan, Elise; Swiecicka, Izabela; Delbrassinne, Laurence; Dierick, Katelijne; Mahillon, Jacques

    2014-04-01

    Bacillus cereus is an important foodborne pathogen causing diarrhoea, emesis and in, rare cases, lethal poisonings. The emetic syndrome is caused by cereulide, a heat-stable toxin. Originally considered as a rather homogenous group, the emetic strains have since been shown to display some diversity, including the existence of two clusters of mesophilic B. cereus and psychrotolerant B. weihenstephanensis. Using pulsed-field gel electrophoresis (PFGE) analysis, this research aimed to better understand the diversity and spatio-temporal occurrence of emetic strains originating from environmental or food niches vs. those isolated from foodborne cases. The diversity was evaluated using a set of 52 B. cereus and B. weihenstephanensis strains isolated between 2000 and 2011 in ten countries. PFGE analysis could discriminate 17 distinct profiles (pulsotypes). The most striking observations were as follows: (1) more than one emetic pulsotype can be observed in a single outbreak; (2) the number of distinct isolates involved in emetic intoxications is limited, and these potentially clonal strains frequently occurred in successive and independent food poisoning cases; (3) isolates from different countries displayed identical profiles; and (4) the cereulide-producing psychrotolerant B. weihenstephanensis were, so far, only isolated from environmental niches.

  10. Genotyping of Yersinia enterocolitica biotype 1A strains from clinical and nonclinical origins by pulsed-field gel electrophoresis.

    Science.gov (United States)

    Campioni, Fábio; Falcão, Juliana P

    2014-06-01

    Yersinia enterocolitica biotype 1A (B1A) strains are considered mainly nonpathogenic. However, some studies considered strains of this biotype to be the causal agents of infections in humans and animals. In South America, there are no studies that have compared clinical and nonclinical strains of B1A typed by pulsed-field gel electrophoresis (PFGE) and none that have compared the capability of different enzymes on typing these strains. This study typed 51 Y. enterocolitica B1A strains isolated in Brazil and Chile by PFGE, testing the enzymes XbaI, NotI, and XhoI. The resulting dendrograms discriminated the strains in 47, 40, and 49 pulsotypes generated by the cleavage with the enzymes XbaI, NotI, and XhoI, respectively. The majority of the strains were grouped independently of their clinical or nonclinical origins. The high discriminatory power of PFGE confirmed the heterogeneity of B1A strains but could not divide the strains studied into clusters that differed in the frequency of some virulence genes as observed in studies using other methodologies.

  11. Frequencies of virulence genes and pulse field gel electrophoresis fingerprints in Escherichia coli isolates from canine pyometra.

    Science.gov (United States)

    Maluta, Renato P; Borges, Clarissa A; Beraldo, Lívia G; Cardozo, Marita V; Voorwald, Fabiana A; Santana, André M; Rigobelo, Everlon C; Toniollo, Gilson H; Avila, Fernando A

    2014-11-01

    Escherichia coli is the most common bacterial agent isolated from canine pyometra. The frequencies of 24 virulence genes and pulsed field gel electrophoresis (PFGE) profiles were determined for 23 E. coli isolates from cases of canine pyometra in Brazil. The frequencies of virulence genes were 91.3% fimH, 91.3% irp-2, 82.6% fyuA, 56.5% iroN, 47.8% traT, 39.1% usp, 34.8% sfaD/E, 34.8% tsh, 30.4% papC, 30.4% hlyA, 26.1% papGIII, 26.1% cnf-1, 21.7% papE/F, 21.7% iss, 17.4% iutA, 17.4% ompT, 17.4% cvaC, 17.4% hlyF, 17.4% iucD, 13.0% iucC, 13.0% astA, 4.3% papGII, 0% afaB/C and 0% papGI. The high frequency of yersiniabactin (fyuA and irp2) and salmochelin (iroN) genes suggests that iron uptake systems might be important in the pathogenesis of canine pyometra. PFGE profiles of 19 isolates were heterogeneous, confirming that E. coli isolates from canine pyometra are unlikely to be epidemic clones.

  12. Arcobacter species and their pulsed-field gel electrophoresis genotypes in Finnish raw milk during summer 2011.

    Science.gov (United States)

    Revez, Joana; Huuskonen, Marianne; Ruusunen, Marjo; Lindström, Miia; Hänninen, Marja-Liisa

    2013-09-01

    The aim of this study was to investigate the occurrence of Arcobacter species in raw milk in Finland. A total of 177 raw milk samples, each from a separate farm, were examined from June to August 2011. Arcobacter species were isolated using an enrichment and selective detection procedure. Overall, 26 (15 % ) of the 177 samples yielded Arcobacter spp. Samples from 25 farms were positive for Arcobacter butzleri and from 1 farm for Arcobacter cryaerophilus. Moreover, both Arcobacter butzleri and A. cryaerophilus were recovered from 1 positive sample. To evaluate a possible genetic variability, one strain of A. butzleri from each farm and the A. cryaerophilus sample were analyzed by pulsed-field gel electrophoresis. Genotyping revealed that Arcobacter spp. populations are heterogeneous, and no dominant clone has spread in the investigated samples. Our study is the first report on the isolation of both A. butzleri and A. cryaerophilus in raw milk in Finland. Based on our findings, the presence of Arcobacter species in raw milk may pose a potential hazard for human health, in particular for consumers who prefer drinking unpasteurized milk.

  13. Epidemiological typing of Campylobacter isolates from meat processing plants by pulsed-field gel electrophoresis, fatty acid profile typing, serotyping, and biotyping.

    Science.gov (United States)

    Steele, M; McNab, B; Fruhner, L; DeGrandis, S; Woodward, D; Odumeru, J A

    1998-07-01

    Campylobacter spp. are a leading cause of bacterial gastroenteritis. Foods of animal origin, particularly under-cooked poultry, are common sources of Campylobacter species associated with disease in humans. A collection of 110 Campylobacter jejuni and 31 C. coli human and environmental isolates from different Ontario, Canada, abattoirs were analyzed by pulsed-field gel electrophoresis, fatty acid profile typing, and biotyping. Previously collected serotyping data for the same isolates were also analyzed in this study. Pulsed-field gel electrophoresis was found to be the most discriminatory of the typing methods, followed by serotyping, fatty acid profile typing, and biotyping. A wide variety of typing profiles were observed within the isolates, suggesting that several different Campylobacter sp. strains were present within the abattoirs.

  14. Pulsed-Field Gel Electrophoresis characterization of Listeria monocytogenes isolates from cheese manufacturing plants in São Paulo, Brazil.

    Science.gov (United States)

    Barancelli, Giovana V; Camargo, Tarsila M; Gagliardi, Natália G; Porto, Ernani; Souza, Roberto A; Campioni, Fabio; Falcão, Juliana P; Hofer, Ernesto; Cruz, Adriano G; Oliveira, Carlos A F

    2014-03-03

    This study aimed to evaluate the occurrence of Listeria monocytogenes in cheese and in the environment of three small-scale dairy plants (A, B, C) located in the Northern region state of São Paulo, Brazil, and to characterize the isolates using conventional serotyping and PFGE. A total of 393 samples were collected and analyzed from October 2008 to September 2009. From these, 136 came from dairy plant A, where only L. seeligeri was isolated. In dairy plant B, 136 samples were analyzed, and L. innocua, L. seeligeri and L. welshimeri were isolated together with L. monocytogenes. In dairy plant C, 121 samples were analyzed, and L. monocytogenes and L. innocua were isolated. Cheese from dairy plants B and C were contaminated with Listeria spp, with L. innocua being found in Minas frescal cheese from both dairy plants, and L. innocua and L. monocytogenes in Prato cheese from dairy plant C. A total of 85 L. monocytogenes isolates were classified in 3 serotypes: 1/2b, 1/2c, and 4b, with predominance of serotype 4b in both dairy plants. The 85 isolates found in the dairy plants were characterized by genomic macrorestriction using ApaI and AscI with Pulsed Field Gel Electrophoresis (PFGE). Macrorestriction yielded 30 different pulsotypes. The presence of indistinguishable profiles repeatedly isolated during a 12-month period indicated the persistence of L. monocytogenes in dairy plants B and C, which were more than 100 km away from each other. Brine used in dairy plant C contained more than one L. monocytogenes lineage. The routes of contamination were identified in plants B and C, and highlighted the importance of using molecular techniques and serotyping to track L. monocytogenes sources of contamination, distribution, and routes of contamination in dairy plants, and to develop improved control strategies for L. monocytogenes in dairy plants and dairy products.

  15. Plasmid profile and pulsed-field gel electrophoresis analysis of Salmonella enterica isolates from humans in Turkey.

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    Kerem Ozdemir

    Full Text Available This study was conducted for typing Salmonella enterica subspecies enterica strains in Turkey using pulsed-field gel electrophoresis (PFGE and plasmid DNA profile analysis. Fourty-two strains were isolated from clinical samples obtained from unrelated patients with acute diarrhea. The samples were collected from state hospitals and public health laboratories located at seven provinces in different regions of Turkey at different times between 2004 and 2010. The strains were determined to belong to 4 different serovars. The Salmonella enterica strains belonged to the serovars Salmonella Enteritidis (n = 23, Salmonella Infantis (n = 14, Salmonella Munchen (n = 2, and Salmonella Typhi (n = 3. Forty-two Salmonella enterica strains were typed with PFGE methods using XbaI restriction enzyme and plasmid analysis. At the end of typing, 11 different PFGE band profiles were obtained. Four different PFGE profiles (type 1, 4, 9, and 10 were found among serotype S. Enteritidis species, 3 different PFGE profiles (type 3, 5, 6 were found among S. Infantis species, 2 different PFGE profiles were found among S. Typhi species (type 2 and 11, and 2 different PFGE profiles were found among S. Munchen species (type 7, 8. The UPGMA dendrogram was built on the PFGE profiles. In this study, it was determined that 4 strains of 42 Salmonella enterica strains possess no plasmid, while the isolates have 1-3 plasmids ranging from 5.0 to 150 kb and making 12 different plasmid profiles (P1-P12. In this study, we have applied the analysis of the PFGE patterns and used bioinformatics methods to identify both inter and intra serotype relationships of 4 frequently encountered serotypes for the first time in Turkey.

  16. Comparison of multilocus sequence typing and pulsed-field gel electrophoresis for Salmonella spp. identification in surface water

    Science.gov (United States)

    Kuo, Chun Wei; Hao Huang, Kuan; Hsu, Bing Mu; Tsai, Hsien Lung; Tseng, Shao Feng; Kao, Po Min; Shen, Shu Min; Chou Chiu, Yi; Chen, Jung Sheng

    2013-04-01

    Salmonella is one of the most important pathogens of waterborne diseases with outbreaks from contaminated water reported worldwide. In addition, Salmonella spp. can survive for long periods in aquatic environments. To realize genotypes and serovars of Salmonella in aquatic environments, we isolated the Salmonella strains by selective culture plates to identify the serovars of Salmonella by serological assay, and identify the genotypes by Multilocus sequence typing (MLST) based on the sequence data from University College Cork (UCC), respectively. The results show that 36 stream water samples (30.1%) and 18 drinking water samples (23.3%) were confirmed the existence of Salmonella using culture method combined PCR specific invA gene amplification. In this study, 24 cultured isolates of Salmonella from water samples were classified to fifteen Salmonella enterica serovars. In addition, we construct phylogenetic analysis using phylogenetic tree and Minimum spanning tree (MST) method to analyze the relationship of clinical, environmental, and geographical data. Phylogenetic tree showed that four main clusters and our strains can be distributed in all. The genotypes of isolates from stream water are more biodiversity while comparing the Salmonella strains genotypes from drinking water sources. According to MST data, we can found the positive correlation between serovars and genotypes of Salmonella. Previous studies revealed that the result of Pulsed field gel electrophoresis (PFGE) method can predict the serovars of Salmonella strain. Hence, we used the MLST data combined phylogenetic analysis to identify the serovars of Salmonella strain and achieved effectiveness. While using the geographical data combined phylogenetic analysis, the result showed that the dominant strains were existed in whole stream area in rainy season. Keywords: Salmonella spp., MLST, phylogenetic analysis, PFGE

  17. Pulsed-field gel electrophoresis analysis of Bordetella pertussis isolates circulating in Europe from 1998 to 2009.

    Science.gov (United States)

    Advani, Abdolreza; Hallander, Hans O; Dalby, Tine; Krogfelt, Karen Angeliki; Guiso, Nicole; Njamkepo, Elisabeth; von Könnig, Carl Heinz Wirsing; Riffelmann, Marion; Mooi, Frits R; Sandven, Per; Lutynska, Anna; Fry, Norman K; Mertsola, Jussi; He, Qiushui

    2013-02-01

    Between 1998 and 2009, Bordetella pertussis clinical isolates were collected during three periods, i.e., 1998 to 2001 (n = 102), 2004 to 2005 (n = 154), and 2007 to 2009 (n = 140), from nine countries with distinct vaccination programs, i.e., Denmark, Finland, France, Germany, The Netherlands, Norway, Poland, Sweden, and the United Kingdom. Pulsed-field gel electrophoresis (PFGE) analysis was performed according to standardized recommendations for epidemiological typing of B. pertussis. There were 81 different PFGE profiles, five of which (BpSR3, BpSR5, BpSR10, BpSR11, and BpSR12) were observed in 61% of the 396 isolates and shown to be predominant in almost all countries. The major profile, BpSR11, showed a decreasing trend from 25% to 30% in 1998 to 2005 to 13% in 2007 to 2009, and there were increases in BpSR3 and BpSR10 from 0% and 8% to 21% and 22%, respectively. One difference between these profiles is that BpSR11 contains isolates harboring the fim3-2 allele and BpSR3 and BpSR10 contain isolates harboring the fim3-1 allele. The total proportion of the five predominant profiles increased from 44% in 1998 to 2001 to 63% in 2004 to 2005 to 70% in 2007 to 2009. In conclusion, common PFGE profiles were identified in B. pertussis populations circulating in European countries with different vaccination programs and different vaccine coverages. These prevalent isolates contain the novel pertussis toxin promoter ptxP3 allele. However, there is evidence for diversifying selection between ptxP3 strains characterized by distinct PFGE profiles. This work shows that, even within a relatively short time span of 10 years, successful isolates which spread through Europe and cause large shifts in B. pertussis populations may emerge.

  18. Random amplification of polymorphic DNA (RAPD), pulsed-field gel electrophoresis (PFGE) and phage-typing in the analysis of a hospital outbreak of Salmonella enteritidis

    DEFF Research Database (Denmark)

    Skibsted, U.; Baggesen, Dorte Lau; Dessau, R.

    1998-01-01

    Isolates of Salmonella Enteritidis from 81 patients from Herlev Hospital or from Copenhagen County were analysed by random amplification of polymorphic DNA (RAPD), pulsed-field gel electrophoresis (PFGE) and phage-typing. Fourteen polymorphic markers from five decamer primers unambiguously placed...... that RAPD is useful as a tool in investigations of microbial outbreaks in its own right, or to supplement phage-typing and PFGE of Salmonella Enteritidis....

  19. Physical and genetic mapping of the genomes of five Mycoplasma hominis strains by pulsed-field gel electrophoresis

    DEFF Research Database (Denmark)

    Ladefoged, Søren; Christiansen, Gunna

    1992-01-01

    -field gel electrophoresis. All the ApaI, SmaI, BamHI, XhoI, and SalI restriction sites (total of 21 to 33 sites in each strain) were placed on the physical map, yielding an average resolution of 26 kb. The maps were constructed using three different approaches: (i) size determination of DNA fragments...

  20. The gel-forming behaviour of dextran in the presence of KCl: a quantitative 13C and pulsed field gradient (PFG) NMR study.

    Science.gov (United States)

    Naji, L; Schiller, J; Kaufmann, J; Stallmach, F; Kärger, J; Arnold, K

    2003-05-01

    Although the gel forming ability of certain polysaccharides in the presence of ions is a well-known phenomenon, detailed physicochemical mechanisms of such processes are still unknown. In this investigation high resolution 13C NMR as well as 1H pulsed field gradient (PFG) NMR were used to investigate the mobility of dextran in the sol and in the gel state. Gel-formation of dextran can be easily induced by the addition of large amounts of potassium chloride. No major differences in the T(1) relaxation times of dextran in the sol and in the gel state could be observed. Accordingly, the analysis of the 13C NMR spectroscopic data did not provide any indication of an observable line-broadening upon gel-formation. However, a KCl concentration dependent decrease of signal intensity in comparison to an internal standard was detected. On the other hand, the PFG NMR studies clearly indicated a gradual diminution of the self-diffusion coefficient of the dextran with increasing molecular weight as well as in the presence of potassium chloride. These measurements revealed in agreement with spectroscopic data that at least one potassium ion per monomer subunit (i.e. one glycopyranose residue) is necessary for gel formation.

  1. Pulsed Field Gel Electrophoresis (PFGE: a DNA finger printing technique to study the genetic diversity of blood disease bacterium of banana

    Directory of Open Access Journals (Sweden)

    HADIWIYONO

    2011-01-01

    Full Text Available Hadiwiyono, Widada J, Subandiyah S, Fegan F (2011 Pulsed Field Gel Electrophoresis (PFGE: a DNA finger printing technique to study the genetic diversity of blood disease bacterium of banana. Biodiversitas 12: 12-16. Blood disease bacterium (BDB is the most important pathogen of bananas in Indonesia. In some field, the disease incidence reaches over 80%. Epidemiologically, the disease is similar to moko disease in South America and bugtok disease in the Philippines caused by Ralstonia solanacearum race 2. However, BDB is different in phenotype and genotype from the two diseases. Previously BDB was limited in South Sulawesi since 1920s – 1980s and recently was reported in 27 of 30 provinces in Indonesia. Pulsed-Field Gel Electrophoresis (PFGE is a genomic DNA fingerprinting method, which employs rare cutting restriction endonucleases to digest genome prior to electrophoresis using specialized condition to separate of large DNA fragments. The results showed that PFGE analysis was a discriminative tool to study the genetic diversity of BDB. Based on the PFGE analysis, BDB isolates obtained from different localities in Yogyakarta and Central Java were quit diverse.

  2. Tracing outbreaks of Streptococcus equi infection (strangles) in horses using sequence variation in the seM gene and pulsed-field gel electrophoresis.

    Science.gov (United States)

    Lindahl, Susanne; Söderlund, Robert; Frosth, Sara; Pringle, John; Båverud, Viveca; Aspán, Anna

    2011-11-21

    Strangles is a serious respiratory disease in horses caused by Streptococcus equi subspecies equi (S. equi). Transmission of the disease occurs by direct contact with an infected horse or contaminated equipment. Genetically, S. equi strains are highly homogenous and differentiation of strains has proven difficult. However, the S. equi M-protein SeM contains a variable N-terminal region and has been proposed as a target gene to distinguish between different strains of S. equi and determine the source of an outbreak. In this study, strains of S. equi (n=60) from 32 strangles outbreaks in Sweden during 1998-2003 and 2008-2009 were genetically characterized by sequencing the SeM protein gene (seM), and by pulsed-field gel electrophoresis (PFGE). Swedish strains belonged to 10 different seM types, of which five have not previously been described. Most were identical or highly similar to allele types from strangles outbreaks in the UK. Outbreaks in 2008/2009 sharing the same seM type were associated by geographic location and/or type of usage of the horses (racing stables). Sequencing of the seM gene generally agreed with pulsed-field gel electrophoresis profiles. Our data suggest that seM sequencing as a epidemiological tool is supported by the agreement between seM and PFGE and that sequencing of the SeM protein gene is more sensitive than PFGE in discriminating strains of S. equi.

  3. Associated risk factors and pulsed field gel electrophoresis of nasal isolates of Staphylococcus aureus from medical students in a tertiary hospital in Lagos, Nigeria

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    Solayide A. Adesida

    2007-02-01

    Full Text Available Staphylococcus aureus infections are growing problems worldwide with important implications in hospitals. The organism is normally present in the nasal vestibule of about 35% of apparently healthy individuals and its carriage varies between different ethnic and age groups. Staphylococcal nasal carriage among health workers is particularly important to establish new clones and track origin of infections during outbreak situations. To determine the carriage rate and compare the pulsed field gel patterns of the strains, nasal swabs were collected from 185 medical students in a teaching hospital in Lagos, Nigeria. Isolates of S. aureus were tested for heamolysin production, methicillin sensitivity and Pulsed Field Gel Electrophoresis (PFGE was performed. The results showed S.aureus nasal carrier rate of 14% with significant rate among males compared to females. All the isolates produced heamolysin. Antibiotic susceptibility pattern revealed that majority of the isolates was susceptible. Five strains (19% harboured resistant determinants to penicillin and tetracycline. None of the strains was resistant to methicillin. 44% of the isolates typed by PFGE had type B, the most predominant pulsotype. PFGE A clone exhibited a single resistance phenotype suggesting a strong clonal relationship that could punctual an outbreak in the hospital. The results speculate that nasal carriage among medical personnel could be a function of various risk factors. Personal hygiene and behaviour may however be the means to reducing colonization and spread of S.aureus in our hospitals.

  4. Characterization of nosocomial Serratia marcescens isolates: comparison of Fourier-transform infrared spectroscopy with pulsed-field gel electrophoresis of genomic DNA fragments and multilocus enzyme electrophoresis.

    Science.gov (United States)

    Irmscher, H M; Fischer, R; Beer, W; Seltmann, G

    1999-07-01

    A total of 66 Serratia marcescens isolates from 46 patients was investigated by macrorestriction using XbaI followed by pulsed-field gel electrophoresis. 7 restriction fragment patterns attributable to more than one patient and 9 individual patterns were identified. The isolates were additionally characterized by multilocus enzyme electrophoresis and Fourier-transform infrared spectroscopy. The macrorestriction patterns and the multilocus enzyme electrophoresis patterns corresponded fairly well while the classifications derived from these methods were not completely congruent. The grouping achieved by Fourier-transform infrared spectroscopy on the basis of high (> 1000) and moderately high heterogeneity values (300) was consistent with the macrorestriction results. Grouping on a lower heterogeneity level did not contribute to further discrimination. In general, Fourier-transform infrared spectroscopy was less discriminatory than the two other methods, but easier to perform. Therefore, laboratories equipped with the necessary devices may use it to rapidly select bacterial isolates for macrorestriction or other well established characterization procedures.

  5. Use of pulsed field gel electrophoresis (PFGE and single-enzyme amplified fragment length polymorphism(SE-AFLP to subtype isolates of Salmonella entericaserotype enteritidis

    Directory of Open Access Journals (Sweden)

    Caterina Mammina

    2005-03-01

    Full Text Available

    Serotype Enteritidis is still the main serotype infecting humans and poultry worldwide. Subtyping of isolates belonging to this serotype is difficult, because of the wide clonal circulation of a few bacterial clones.

    This study presents the results of the characterization of 49 isolates of S. Enteritidis identified at the southern Italy Centre for Enteric Pathogens (CEPIM during the years 2002-2003 by the methods of Pulsed Field Gel Electrophoresis (PFGE and Single-Enzyme Amplified Fragment Length Polymorphism (SE-AFLP.

    Clustering of the strains by SE-AFLP and PFGE is very similar, but the first technique is more rapid and user-friendly and does not require sophisticated equipment. Further work is needed for a more accurate assessment of SEAFLP, but preliminary results suggest it could be a promising support to epidemiological investigations.

  6. Comparison of Streptococcus mutans strains from children with caries-active, caries-free and gingivitis clinical diagnosis by pulsed-field gel electrophoresis.

    Science.gov (United States)

    Herczegh, Anna; Ghidán, A; Deseo, Kinga; Kamotsay, Katalin; Tarján, Ildikó

    2008-12-01

    A study was conducted to compare the DNA structure of Streptococcus mutans strains in children with caries-active, caries-free, and gingivitis clinical diagnosis. Twenty-eight Streptococcus mutans strains from 100 children's plaques were examined by pulsed-field gel electrophoresis (PFGE) method. The classified strains were closely related to one another, though the strains originated from different disease groups. Three identical pairs were found, but the pairs in two cases belonged to different disease groups. The results of the PFGE experiments suggest that there is no correlation between the different DNA patterns ofS. mutans strains and their cariogenecity. So the different DNA strains ofS. mutans are not the only determining factor in the development of dental caries.

  7. Pulsed-field gel electrophoresis (PFGE) typing of Listeria strains isolated from a meat processing plant over a 2-year period.

    Science.gov (United States)

    Senczek, D; Stephan, R; Untermann, F

    2000-12-05

    As part of a hygiene monitoring program in a meat processing plant a total of 131 Listeria isolates were detected by sampling different processing areas and meat products within a 2-year period. The isolates were differentiated by means of phenotypic characteristics. Furthermore, the genomic ApaI and SmaI fragment patterns of all isolates were examined by pulsed-field gel electrophoresis (PFGE). PFGE using SmaI and ApaI yielded 15 (Listeria monocytogenes), 20 (Listeria innocua) and six (Listeria welshimeri) pulsotypes. Of the environmental Listeria monocytogenes isolates the predominating PFGE-type B was clearly associated with processing area A whereas PFGE-type E predominated in the meat products. Moreover, the study showed the persistence of closely related Listeria strains over a 2-year period in the environment of this meat processing plant.

  8. Multilocus sequence typing and pulsed-field gel electrophoresis analysis of Oenococcus oeni from different wine-producing regions of China.

    Science.gov (United States)

    Wang, Tao; Li, Hua; Wang, Hua; Su, Jing

    2015-04-16

    The present study established a typing method with NotI-based pulsed-field gel electrophoresis (PFGE) and stress response gene schemed multilocus sequence typing (MLST) for 55 Oenococcus oeni strains isolated from six individual regions in China and two model strains PSU-1 (CP000411) and ATCC BAA-1163 (AAUV00000000). Seven stress response genes, cfa, clpL, clpP, ctsR, mleA, mleP and omrA, were selected for MLST testing, and positive selective pressure was detected for these genes. Furthermore, both methods separated the strains into two clusters. The PFGE clusters are correlated with the region, whereas the sequence types (STs) formed by the MLST confirm the two clusters identified by PFGE. In addition, the population structure was a mixture of evolutionary pathways, and the strains exhibited both clonal and panmictic characteristics.

  9. Pulsed-field gel electrophoresis typing of Escherichia coli strains from samples collected before and after pivmecillinam or placebo treatment of uncomplicated community-acquired urinary tract infection in women

    DEFF Research Database (Denmark)

    Ejrnaes, Karen; Sandvang, Dorthe; Lundgren, Bettina

    2006-01-01

    The primary infecting Escherichia coli strains from 156 women with community-acquired uncomplicated urinary tract infection (UTI) randomized to pivmecillinam or placebo and the E. coli strains causing UTI at two follow-up visits were typed using pulsed-field gel electrophoresis (PFGE). In the piv......The primary infecting Escherichia coli strains from 156 women with community-acquired uncomplicated urinary tract infection (UTI) randomized to pivmecillinam or placebo and the E. coli strains causing UTI at two follow-up visits were typed using pulsed-field gel electrophoresis (PFGE...

  10. Enhanced discrimination of highly clonal ST22-methicillin-resistant Staphylococcus aureus IV isolates achieved by combining spa, dru, and pulsed-field gel electrophoresis typing data.

    LENUS (Irish Health Repository)

    Shore, Anna C

    2010-05-01

    ST22-methicillin-resistant Staphylococcus aureus type IV (ST22-MRSA-IV) is endemic in Irish hospitals and is designated antibiogram-resistogram type-pulsed-field group (AR-PFG) 06-01. Isolates of this highly clonal strain exhibit limited numbers of pulsed-field gel electrophoresis (PFGE) patterns and spa types. This study investigated whether combining PFGE and spa typing with DNA sequencing of the staphylococcal cassette chromosome mec element (SCCmec)-associated direct repeat unit (dru typing) would improve isolate discrimination. A total of 173 MRSA isolates recovered in one Irish hospital during periods in 2007 and 2008 were investigated using antibiogram-resistogram (AR), PFGE, spa, dru, and SCCmec typing. Isolates representative of each of the 17 pulsed-field group 01 (PFG-01) spa types identified underwent multilocus sequence typing, and all isolates were ST22. Ninety-seven percent of isolates (168 of 173) exhibited AR-PFG 06-01 or closely related AR patterns, and 163 of these isolates harbored SCCmec type IVh. The combination of PFGE, spa, and dru typing methods significantly improved discrimination of the 168 PFG-01 isolates, yielding 65 type combinations with a Simpson\\'s index of diversity (SID) of 96.53, compared to (i) pairwise combinations of spa and dru typing, spa and PFGE typing, and dru and PFGE typing, which yielded 37, 44, and 43 type combinations with SIDs of 90.84, 91.00, and 93.57, respectively, or (ii) individual spa, dru, and PFGE typing methods, which yielded 17, 17, and 21 types with SIDs of 66.9, 77.83, and 81.34, respectively. Analysis of epidemiological information for a subset of PFG-01 isolates validated the relationships inferred using combined PFGE, spa, and dru typing data. This approach significantly enhances discrimination of ST22-MRSA-IV isolates and could be applied to epidemiological investigations of other highly clonal MRSA strains.

  11. Two distinct clones of methicillin-resistant Staphylococcus aureus (MRSA) with the same USA300 pulsed-field gel electrophoresis profile: a potential pitfall for identification of USA300 community-associated MRSA

    DEFF Research Database (Denmark)

    Larsen, Anders Rhod; Goering, Richard; Stegger, Marc;

    2009-01-01

    Analysis of methicillin-resistant Staphylococcus aureus (MRSA) characterized as USA300 by pulsed-field gel electrophoresis identified two distinct clones. One was similar to community-associated USA300 MRSA (ST8-IVa, t008, and Panton-Valentine leukocidin positive). The second (ST8-IVa, t024...

  12. Pulsed-field gel electrophoresis typing of Eschericia coli strains from samples collected before and after pivmecillinam or placebo treatment of uncomplicated community-acquired urinary tract infection in women

    DEFF Research Database (Denmark)

    Ejrnæs, K; Sandvang, D; Lundgren, Bettina

    2006-01-01

    The primary infecting Escherichia coli strains from 156 women with community-acquired uncomplicated urinary tract infection (UTI) randomized to pivmecillinam or placebo and the E. coli strains causing UTI at two follow-up visits were typed using pulsed-field gel electrophoresis (PFGE...

  13. Pulsed-field gel electrophoresis typing of Escherichia coli strains from samples collected before and after pivmecillinam or placebo treatment of uncomplicated community-acquired urinary tract infection in women

    DEFF Research Database (Denmark)

    Ejrnaes, Karen; Sandvang, Dorthe; Lundgren, Bettina

    2006-01-01

    The primary infecting Escherichia coli strains from 156 women with community-acquired uncomplicated urinary tract infection (UTI) randomized to pivmecillinam or placebo and the E. coli strains causing UTI at two follow-up visits were typed using pulsed-field gel electrophoresis (PFGE...

  14. Presence of a novel DNA methylation enzyme in methicillin-resistant Staphylococcus aureus isolates associated with pig farming leads to uninterpretable results in standard pulsed-field gel electrophoresis analysis.

    NARCIS (Netherlands)

    Bens, C.C.; Voss, A.; Klaassen, C.H.W.

    2006-01-01

    Genomic DNA from methicillin-resistant Staphylococcus aureus isolates recovered from pigs and their caretakers proved resistant to SmaI digestion, leading to uninterpretable results in standard pulsed-field gel electrophoresis. This is the result of a yet unknown restriction/methylation system in th

  15. Longitudinal prevalence and molecular typing of Escherichia coli O157:H7 using multiple-locus variable-number tandem-repeats analysis and pulsed field gel electrophoresis in a range cattle herd in California

    Science.gov (United States)

    Objectives –(1) Identify the seasonal pattern and risk factors for Escherichia coli O157:H7 in feces in range cattle in California, (2) Determine strain diversity and transition over time using Multi-Locus Variable-Number Tandem Repeat Analysis (MLVA) and Pulsed Field Gel Electrophoresis (PFGE) Samp...

  16. Prevalence and molecular characterization of Escherichia coli O157:H7 by multiple locus variable number tandem repeat analysis and pulsed field gel electrophoresis in three sheep farming operations in California.

    Science.gov (United States)

    A yearlong study was conducted to determine the fecal prevalence of Escherichia coli O157:H7 in three sheep ranches. Strain diversity and persistence was compared using multiple locus variable number tandem repeat analysis and pulsed field gel electrophoresis. Ranch C, a feedlot, consisted of young ...

  17. Epidemiological Characteristics and Clinical Treatment Outcome of Typhoid Fever in Ningbo, China, 2005-2014: Pulsed-Field Gel Electorophoresis Results Revealing Great Proportion of Common Transmission Sources.

    Science.gov (United States)

    Song, Qifa; Yang, Yuanbin; Lin, Wenping; Yi, Bo; Xu, Guozhang

    2017-09-25

    We aimed to describe the molecular epidemiological characteristics and clinical treatment outcome of typhoid fever in Ningbo, China during 2005-2014. Eighty-eight Salmonella Typhi isolates were obtained from 307 hospitalized patients. Three prevalent pulsed-field gel electrophoresis (PFGE) patterns of 54 isolates from 3 outbreaks were identified. Overall, there were 64 (72.7%) isolates from clustered cases and 24 (27.3%) isolates from sporadic cases. Resistance to nalidixic acid (NAL) (n = 47; 53.4%) and ampicillin (AMP) (n = 40; 45.4%) and rare resistance to tetracycline (TET) (n = 2; 2.3%) and gentamicin (GEN) (n = 2; 2.3%) were observed. No isolates resistant to cefotaxime (CTX), chloramphenicol (CL), ciprofloxacin (CIP), and trimethoprim-sulfamethoxazole (SXT) were found. The occurrence of reduced sensitivity to CIP was 52.3% (n = 46). The medians of fever clearance time in cases with and without complications were 7 (interquartile range (IQR): 4-10) and 5 (IQR: 3-7) days (P = 0.001), respectively, when patients were treated with CIP or levofloxacin (LEV) and/or third-generation cephalosporins (CEP). Rates of serious complications were at low levels: peritonitis (2.3%), intestinal hemorrhage (6.8%), and intestinal perforation (1.1%). The present study revealed a long-term clustering trend with respect to PFGE patterns, occasional outbreaks, and the rapid spread of AMP resistance and decreased CIP susceptibility among S. Typhi isolates in recent years.

  18. Molecular typing of enterohemorrhagic Escherichia coli O157:H7 isolated in Okayama Prefecture using pulsed field gel electrophoresis and random amplification of polymorphic DNA.

    Directory of Open Access Journals (Sweden)

    Funamori Y

    1999-08-01

    Full Text Available Three outbreaks and many isolated cases of enterohemorrhagic Escherichia coli O157:H7 occurred in 1996 and 1997 in Okayama Prefecture, Japan. In an attempt to investigate the route of these infections, the strains isolated from the 3 outbreaks (total 33 strains and 15 isolated cases (total 15 strains were investigated using random amplification of polymorphic DNA (RAPD and pulsed-field gel electrophoresis (PFGE. In addition, 10 strains from an outbreak in Tojo Cho, Hiroshima Prefecture (June 1996, 2 strains from the particular types of meat in Kochi Prefecture, and 42 strains isolated from bovine feces in a farm in Okayama Prefecture were also investigated in the same manner. PFGE was much more useful than RAPD for molecular typing of the clinical isolates, in that it allowed us to classify them into 10 PFGE groups. We noted that the strains differed according to the time and place of the outbreaks (or isolated cases. This indicates that O157:H7 infections in Okayama Prefecture were caused by different strains (although some cases were aggravated by the same strains as were found in other areas. The isolates from bovine feces were classified into 5 groups by PFGE profiles, but none of them were identical to those of the clinical isolates.

  19. Genetic characterization of atypical enteropathogenic Escherichia coli isolates from ewes' milk, sheep farm environments, and humans by multilocus sequence typing and pulsed-field gel electrophoresis.

    Science.gov (United States)

    Otero, Verónica; Rodríguez-Calleja, José-María; Otero, Andrés; García-López, María-Luisa; Santos, Jesús A

    2013-10-01

    A collection of 81 isolates of enteropathogenic Escherichia coli (EPEC) was obtained from samples of bulk tank sheep milk (62 isolates), ovine feces (4 isolates), sheep farm environment (water, 4 isolates; air, 1 isolate), and human stool samples (9 isolates). The strains were considered atypical EPEC organisms, carrying the eae gene without harboring the pEAF plasmid. Multilocus sequence typing (MLST) was carried out with seven housekeeping genes and 19 sequence types (ST) were detected, with none of them having been previously reported for atypical EPEC. The most frequent ST included 41 strains isolated from milk and human stool samples. Genetic typing by pulsed-field gel electrophoresis (PFGE) resulted in 57 patterns which grouped in 24 clusters. Comparison of strains isolated from the different samples showed phylogenetic relationships between milk and human isolates and also between milk and water isolates. The results obtained show a possible risk for humans due to the presence of atypical EPEC in ewes' milk and suggest a transmission route for this emerging pathogen through contaminated water.

  20. Molecular Typing of Fluoroquinolone-Resistant Campylobacter jejuni Isolated from Broilers in Japan Using Multilocus Sequence Typing and Pulsed-Field Gel Electrophoresis.

    Science.gov (United States)

    Ozawa, Manao; Hiki, Mototaka; Kawanishi, Michiko; Abo, Hitoshi; Kojima, Akemi; Asai, Tetsuo; Hamamoto, Shuichi

    2016-01-01

    Fluoroquinolone-resistant Campylobacter jejuni isolates from broilers in Japan were characterized using multilocus sequence typing and pulsed-field gel electrophoresis (PFGE) in order to elucidate the genetic relationship between these strains. Forty-three of the isolates were classified into 20 sequence types and were clustered into 21 PFGE types with 70% similarity. The most dominant clonal complex (CC) was CC-21 (41.9%). Diverse PFGE patterns were observed within the same CC, but the combined analysis of PFGE type and CC revealed that the strains with the same combination were isolated from the same district or neighboring districts. On the other hand, strains with the same combination pattern were also isolated from geographically distant districts. Our results elucidate two possible reasons for the prevalence of fluoroquinolone-resistant C. jejuni among broiler farms: (1) the resistant C. jejuni is clonally disseminated within the limited area, and (2) susceptible C. jejuni acquired fluoroquinolone resistance during the use of fluoroquinolone on the farms.

  1. High genetic diversity of Enterococcus faecium and Enterococcus faecalis clinical isolates by pulsed-field gel electrophoresis and multilocus sequence typing from a hospital in Malaysia.

    Science.gov (United States)

    Weng, Poh Leng; Ramli, Ramliza; Shamsudin, Mariana Nor; Cheah, Yoke-Kqueen; Hamat, Rukman Awang

    2013-01-01

    Little is known on the genetic relatedness and potential dissemination of particular enterococcal clones in Malaysia. We studied the antibiotic susceptibility profiles of Enterococcus faecium and Enterococcus faecalis and subjected them to pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). E. faecium and E. faecalis displayed 27 and 30 pulsotypes, respectively, and 10 representative E. faecium and E. faecalis isolates (five each) yielded few different sequence types (STs): ST17 (2 isolates), ST78, ST203, and ST601 for E. faecium, and ST6, ST16, ST28, ST179, and ST399 for E. faecalis. Resistance to tazobactam-piperacillin and ampicillin amongst E. faecium isolates was highly observed as compared to E. faecalis isolates. All of the isolates were sensitive to vancomycin and teicoplanin. The presence of epidemic and nosocomial strains of selected E. faecium STs: 17, 78, and 203 and E. faecalis ST6 as well as high rates of resistance to multiple antibiotics amongst E. faecium isolates is of a particular concern.

  2. Analysis of ventilator-associated pneumonia infection route by genome macrorestriction-pulsed-field gel electrophoresis and its prevention with combined nursing strategies.

    Science.gov (United States)

    Wang, Xiaodong; Wang, Junping; Li, Jing; Wang, Jing

    2014-12-01

    The aim of the present study was to explore the infection route of ventilator-associated pneumonia (VAP) and assess the effectiveness of a combined nursing strategy to prevent VAP in intensive care units. Bacteria from the gastric juice and drainage from the hypolarynx and lower respiratory tracts of patients with VAP were analyzed using genome macrorestriction-pulsed-field gel electrophoresis (GM-PFGE). A total of 124 patients with tracheal intubation were placed in the intervention group and were treated with a combined nursing strategy, comprising mosapride (gastric motility stimulant) administration and semi-reclining positioning. A total of 112 intubated patients were placed in the control group and received routine nursing care. The incidence rate of VAP, days of ventilation and mortality rate of patients were compared between the two groups. The GM-PFGE fingerprinting results of three strains of Pseudomonas aeruginosa from the gastric juice, subglottic secretion drainage and drainage of the lower respiratory tract in patients with VAP were similar across groups. The number of days spent on a ventilator by patients in the intervention group (7.37±5.32 days) was lower compared with that by patients in the control group (12.34±4.98 days) (Pnursing strategy (Pnursing strategy of gastric motility stimulant administration and the adoption of a semi-reclining position was effective in preventing VAP by reducing the occurrence of GER.

  3. Characterization of Salmonella isolates from municipal sewage, patients, foods, and animals in Greece using antimicrobial susceptibility testing and pulsed field gel electrophoresis

    Directory of Open Access Journals (Sweden)

    Theofilos Papadopoulos

    2016-03-01

    Full Text Available Aims: We aimed to compare Salmonella isolates from different sources using molecular and phenotypic methods, targeting better possibility of understanding the epidemiology of this organism in the Greek context with emphasis in municipal wastewater. Materials and Methods: In this study, we used pulsed field gel electrophoresis (PFGE in combination with antimicrobial susceptibility testing to analyze a total of 88 Salmonella Enterica isolates from municipal sewage (n=25, humans (n=36, animals (n=24, and foods (n=3 in Greece. Results: The higher resistance rates were found to the following antimicrobials: streptomycin (59.1%, tetracycline (47.7%, nalidixic acid (46.6%, ampicillin (37.5%, and oxolinic acid (35.2%. Resistance to ciprofloxacin was not observed; 22 isolates (25% were sensitive to all 9 antimicrobials, 36%, 25% and 12% of human, animal and wastewater origin, respectively, showing a significant difference. Salmonella ser. Hadar was the serovar with the highest resistance rates followed by Salmonella ser. Anatum and Salmonella ser. Typhimurium; Salmonella ser. Infantis strains were almost pansusceptible. Cluster analysis did not reveal close genetic relationship between human animal food and wastewater strains belonging to the same serovars. In most of the cases, distinct clusters were observed between human and non-human isolates indicating diversity and no epidemiological connection. Conclusion: This study indicates that municipal wastewater would be of interest to further monitor the community’s prevalence of subclinical or non-reported S. Enterica infections.

  4. Rapid and high-resolution distinction of community-acquired and nosocomial Staphylococcus aureus isolates with identical pulsed-field gel electrophoresis patterns and spa types.

    Science.gov (United States)

    Glasner, Corinna; Sabat, Artur J; Dreisbach, Annette; Larsen, Anders R; Friedrich, Alexander W; Skov, Robert L; van Dijl, Jan Maarten

    2013-03-01

    Methicillin-resistant Staphylococcus aureus (MRSA) represent a serious threat for public health worldwide. Of particular concern is the emergence of community-acquired MRSA, which is often difficult to distinguish from nosocomial MRSA due to a lack of suitable typing methods for early detection. For example, the USA300 pulsed-field gel electrophoresis (PFGE) pattern includes both the 'classical' community-acquired USA300 clone with spa type t008 and an epidemiologically unrelated nosocomial clone with spa type t024. Likewise, spa typing cannot distinguish the classic USA300 from nosocomial MRSA with the spa type t008. Since the fast and high-resolution distinction of these S. aureus types is important for infection prevention and surveillance, we investigated whether multiple-locus variable number tandem repeat fingerprinting (MLVF) can be applied to overcome these limitations. Indeed, MLVF correctly grouped 91 MRSA isolates belonging to the classic USA300 lineage, nosocomial MRSA isolates with the USA300 PFGE profile and spa type t024, and nosocomial MRSA isolates with spa type t008 into 3 distinct clusters. Importantly, several sub-clusters were also identified, reflecting epidemiological relationships between the respective isolates. We conclude that MLVF has the discriminatory power needed to rapidly distinguish very similar community-acquired and nosocomial MRSA isolates and that MLVF-based sub-clustering of isolates is highly useful for epidemiological investigations, outbreak prevention, and control. Copyright © 2012 Elsevier GmbH. All rights reserved.

  5. Cost-Effectiveness and Efficacy of spa, SCCmec, and PVL Genotyping of Methicillin-Resistant Staphylococcus aureus as Compared to Pulsed-Field Gel Electrophoresis

    Science.gov (United States)

    Li, Vincent; Chui, Linda; Louie, Lisa; Simor, Andrew; Golding, George R.; Louie, Marie

    2013-01-01

    Pulsed-field gel electrophoresis (PFGE) is a valuable molecular typing assay used for methicillin-resistant Staphylococcus aureus (MRSA) surveillance and genotyping. However, there are several limitations associated with PFGE. In Alberta, Canada, the significant increase in the number of MRSA isolates submitted to the Provincial Laboratory for Public Health (ProvLab) for PFGE typing led to the need for an alternative genotyping method. In this study, we describe the transition from PFGE to Staphylococcus protein A (spa), Staphylococcal cassette chromosome (SCCmec), and Panton-Valentine leukocidin (PVL) typing. A total of 1915 clinical MRSA isolates collected from 2005 to 2009 were used to develop and validate an algorithm for assigning PFGE epidemic types using spa, SCCmec, and PVL typing and the resulting data was used to populate a new Alberta MRSA typing database. An additional 12620 clinical MRSA isolates collected from 2010 to 2012 as part of ongoing routine molecular testing at ProvLab were characterized using the new typing algorithm and the Alberta MRSA typing database. Switching to spa, SCCmec, and PVL from PFGE typing substantially reduced hands-on and turn-around times while maintaining historical PFGE epidemic type designations. This led to an approximate $77,000 reduction in costs from 2010 to 2012. PFGE typing is still required for a small subset of MRSA isolates that have spa types that are rare, novel, or associated with more than one PFGE epidemic type. PMID:24244440

  6. Comparison of pulsed-field gel electrophoresis & repetitive sequence-based PCR methods for molecular epidemiological studies of Escherichia coli clinical isolates

    Directory of Open Access Journals (Sweden)

    Il Kwon Bae

    2014-01-01

    Full Text Available Background & objectives: PFGE, rep-PCR, and MLST are widely used to identify related bacterial isolates and determine epidemiologic associations during outbreaks. This study was performed to compare the ability of repetitive sequence-based PCR (rep-PCR and pulsed-field gel electrophoresis (PFGE to determine the genetic relationships among Escherichia coli isolates assigned to various sequence types (STs by two multilocus sequence typing (MLST schemes. Methods: A total of 41 extended-spectrum β-lactamase- (ESBL- and/or AmpC β-lactamase-producing E. coli clinical isolates were included in this study. MLST experiments were performed following the Achtman′s MLST scheme and the Whittam′s MLST scheme, respectively. Rep-PCR experiments were performed using the DiversiLab system. PFGE experiments were also performed. Results: A comparison of the two MLST methods demonstrated that these two schemes yielded compatible results. PFGE correctly segregated E. coli isolates belonging to different STs as different types, but did not group E. coli isolates belonging to the same ST in the same group. Rep-PCR accurately grouped E. coli isolates belonging to the same ST together, but this method demonstrated limited ability to discriminate between E. coli isolates belonging to different STs. Interpretation & conclusions: These results suggest that PFGE would be more effective when investigating outbreaks in a limited space, such as a specialty hospital or an intensive care unit, whereas rep-PCR should be used for nationwide or worldwide epidemiology studies.

  7. Multilocus sequence typing reveals a lack of diversity among Escherichia coli O157:H7 isolates that are distinct by pulsed-field gel electrophoresis.

    Science.gov (United States)

    Noller, Anna C; McEllistrem, M Catherine; Stine, O Colin; Morris, J Glenn; Boxrud, David J; Dixon, Bruce; Harrison, Lee H

    2003-02-01

    Escherichia coli O157:H7 is a major cause of foodborne illness in the United States. Pulsed-field gel electrophoresis (PFGE) is the molecular epidemiologic method mostly commonly used to identify food-borne outbreaks. Although PFGE is a powerful epidemiologic tool, it has disadvantages that make a DNA sequence-based approach potentially attractive. Multilocus sequence typing (MLST) analyzes the internal fragments of housekeeping genes to establish genetic relatedness between isolates. We sequenced selected portions of seven housekeeping genes and two membrane protein genes (ompA and espA) of 77 isolates that were diverse by PFGE to determine whether there was sufficient sequence variation to be useful as an epidemiologic tool. There was no DNA sequence diversity in the sequenced portions of the seven housekeeping genes and espA. For ompA, all but five isolates had sequence identical to that of the reference strains. E. coli O157:H7 has a striking lack of genetic diversity in the genes we explored, even among isolates that are clearly distinct by PFGE. Other approaches to identify improved molecular subtyping methods for E. coli 0157:H7 are needed.

  8. Pulsed electric fields

    Science.gov (United States)

    The concept of pulsed electric fields (PEF) was first proposed in 1967 to change the behavior or microorganisms. The electric field phenomenon was identified as membrane rupture theory in the 1980s. Increasing the membrane permeability led to the application of PEF assisted extraction of cellular co...

  9. Pulsed-field gel electrophoresis typing of Eschericia coli strains from samples collected before and after pivmecillinam or placebo treatment of uncomplicated community-acquired urinary tract infection in women

    DEFF Research Database (Denmark)

    Ejrnæs, K; Sandvang, D; Lundgren, Bettina;

    2006-01-01

    The primary infecting Escherichia coli strains from 156 women with community-acquired uncomplicated urinary tract infection (UTI) randomized to pivmecillinam or placebo and the E. coli strains causing UTI at two follow-up visits were typed using pulsed-field gel electrophoresis (PFGE). In the piv......, constituting a reservoir for recurrent UTI.......The primary infecting Escherichia coli strains from 156 women with community-acquired uncomplicated urinary tract infection (UTI) randomized to pivmecillinam or placebo and the E. coli strains causing UTI at two follow-up visits were typed using pulsed-field gel electrophoresis (PFGE......). The finding that the majority of UTIs at follow-up are caused by the primary infecting E. coli strain supports the theory of a vaginal and rectal reservoir but could also support the recent discovery that E. coli strains are able to persist in the bladder epithelium despite appropriate antibiotic treatment...

  10. Diversity of pulsed-field gel electrophoresis pulsotypes, serovars, and antibiotic resistance among Salmonella isolates from wild amphibians and reptiles in the California Central Coast.

    Science.gov (United States)

    Gorski, Lisa; Jay-Russell, Michele T; Liang, Anita S; Walker, Samarpita; Bengson, Yingjia; Govoni, Jessica; Mandrell, Robert E

    2013-06-01

    A survey of cold-blooded vertebrates and associated surface waters in a produce-growing region on the Central California Coast was done between May and September 2011 to determine the diversity of Salmonella. Samples from 460 amphibians and reptiles and 119 water samples were collected and cultured for Salmonella. Animals sampled were frogs (n=331), lizards (n=59), newts (n=5), salamanders (n=6), snakes (n=39), and toads (n=20). Salmonella was isolated from 37 individual animals, including frogs, lizards, snakes, and toads. Snakes were the most likely to contain Salmonella, with 59% testing positive followed by 15.3% of lizards, 5% of toads, and 1.2% of frogs. Fifteen water samples (12.6%) were positive. Twenty-two different serovars were identified, and the majority of isolates were S. enterica subsp. IIIb, with subsp. I, II, and IIIa also found. The serovar isolated most frequently was S. enterica subsp. IIIb 16:z₁₀:e,n,x,z₁₅, from snakes and frogs in five different locations. S. enterica subsp. I serovar Typhimurium and the monophasic I 6,8:d:- were isolated from water, and subspecies I Duisburg and its variants were found in animals and water. Some samples contained more than one type of Salmonella. Analysis of pulsed-field gel electrophoresis pulsotypes indicated that some strains persisted in animals and water collected from the same location. Sixty-six isolates displayed antibiotic resistance, with 27 isolates resistant to more than one antibiotic, including a subspecies IIIb isolate from snake having resistance to five different antibiotics. Twenty-three isolates were resistant to more than one class of antibiotic, and six isolates were resistant to three classes. While these subspecies of IIIa and IIIb cause fewer instances of human illness, they may serve as reservoirs of antibiotic resistance, determinants in the environment, and be sources of contamination of leafy greens associated with product recalls.

  11. The optimization of a rapid pulsed-field gel electrophoresis protocol for the typing of Acinetobacter baumannii, Escherichia coli and Klebsiella spp.

    Science.gov (United States)

    Durmaz, Riza; Otlu, Baris; Koksal, Fatih; Hosoglu, Salih; Ozturk, Recep; Ersoy, Yasemin; Aktas, Elif; Gursoy, Nafia Canan; Caliskan, Ahmet

    2009-09-01

    Pulsed-field gel electrophoresis (PFGE) is the most common genotyping method used for the typing of a number of bacterial species. Generally, investigators use their own custom-developed protocol, but a standardized PFGE protocol would allow the comparison of typing results between laboratories and the tracing of strains around the country. In the present study, we optimized a PFGE protocol for subtyping of Acinetobacter baumannii, Escherichia coli and Klebsiella spp., which are commonly isolated from nosocomial infections in many hospitals. Reproducibility of our PFGE procedure was studied three times at 2- to 3-week intervals. Epidemiological concordance of the optimized PFGE procedure was tested on seven isolates of A. baumannii from a previous outbreak and seven A. baumannii isolates randomly selected among the clinical isolates. The optimized PFGE procedure was evaluated on a total of 174 clinical isolates including 62 A. baumannii, 50 E. coli, and 62 Klebsiella spp. The inter-laboratory reproducibility of the optimized protocol was tested at four laboratories. The optimized procedure is completed in 28 h after culturing. It is likely to be cost-effective, due to the reduction in the time, reagent volume and enzyme concentration needed. The procedure showed high concordance with epidemiological data. There were no non-typeable isolates among the tested bacteria. It is reproducible and versatile. This protocol can be used to identify outbreaks and monitor the spreading rate of nosocomial infections caused by the tested bacterial isolates. Furthermore, due to its high intra- and inter-laboratory reproducibility, the protocol has the potential to be useful for comparing PFGE fingerprinting profiles of the isolates from different settings.

  12. Genetic Diversity of Clostridium sporogenes PA 3679 Isolates Obtained from Different Sources as Resolved by Pulsed-Field Gel Electrophoresis and High-Throughput Sequencing.

    Science.gov (United States)

    Schill, Kristin M; Wang, Yun; Butler, Robert R; Pombert, Jean-François; Reddy, N Rukma; Skinner, Guy E; Larkin, John W

    2015-10-30

    Clostridium sporogenes PA 3679 is a nonpathogenic, nontoxic model organism for proteolytic Clostridium botulinum used in the validation of conventional thermal food processes due to its ability to produce highly heat-resistant endospores. Because of its public safety importance, the uncertain taxonomic classification and genetic diversity of PA 3679 are concerns. Therefore, isolates of C. sporogenes PA 3679 were obtained from various sources and characterized using pulsed-field gel electrophoresis (PFGE) and whole-genome sequencing. The phylogenetic relatedness and genetic variability were assessed based on 16S rRNA gene sequencing and whole-genome single nucleotide polymorphism (SNP) analysis. All C. sporogenes PA 3679 isolates were categorized into two clades (clade I containing ATCC 7955 NCA3679 isolates 1961-2, 1990, and 2007 and clade II containing PA 3679 isolates NFL, UW, FDA, and Campbell and ATCC 7955 NCA3679 isolate 1961-4). The 16S maximum likelihood (ML) tree clustered both clades within proteolytic C. botulinum strains, with clade I forming a distinct cluster with other C. sporogenes non-PA 3679 strains. SNP analysis revealed that clade I isolates were more similar to the genomic reference PA 3679 (NCTC8594) genome (GenBank accession number AGAH00000000.1) than clade II isolates were. The genomic reference C. sporogenes PA 3679 (NCTC8594) genome and clade I C. sporogenes isolates were genetically distinct from those obtained from other sources (University of Wisconsin, National Food Laboratory, U.S. Food and Drug Administration, and Campbell's Soup Company). Thermal destruction studies revealed that clade I isolates were more sensitive to high temperature than clade II isolates were. Considering the widespread use of C. sporogenes PA 3679 and its genetic information in numerous studies, the accurate identification and genetic characterization of C. sporogenes PA 3679 are of critical importance. Copyright © 2015, American Society for Microbiology. All

  13. Molecular Epidemiology of Nosocomial Infection: Analysis of chro­mosomal Restriction Fragment Patterns by Pulsed-Field Gel Electro­phoresis

    Directory of Open Access Journals (Sweden)

    Afaf I Shehata

    2010-04-01

    Full Text Available Acinetobacter baumannii is a species of non-fermentative gram-negative coccobacilli commonly found in soil, water and other environmental samples. This bacterium is defined as being strict aerobes, nonmotile, catalase-positive and oxidase-negative. This organism was susceptible to most antibiotics in the 1970s. A. baumannii is an opportunistic pathogen that may be an important threat due to its increasing multidrug resistance and is involved in nosocomial infections that are often severe. The objective of this study was undertaken to elucidate the molecular epidemiology of A. baumannii using the most widely applicable DNA – based typing methods namely Pulsed-Field Gel Electrophoresis (PFGE. These strains comprised isolates from environmental samples, blood, wound, urine, cerebrospinal fluid and tracheal aspirates. PFGE analysis of 81 clinical isolates has been carried out by using CHEF–DR III systems from Bio – Rad and following the protocol of Gautom with some modifications. A 2.00% band tolerance and an optimization of 4.00% were selected for use during comparisons of generated fingerprints or pulsotypes after digestion with Apa I restriction enzyme. Similarity values have been generated using BioNumerics software, cluster analysis was performed by the unweighted pair – group method using arithmetic averages and DNA relatedness was calculated based on Dice coefficient. An interlinkage homology level of 80% between patterns was assumed as the cutoff for defining a close genetic relationship between strains and was used to define the cluster. As per the generated dendogram, isolates were categorized into 18 major groups designated as Strain I to Strain xvIII. Overall, PFGE was able to discriminate the 81 different Acinetobacter baumannii isolates with similarity levels of 63.63%.

  14. Transmission of endemic ST22-MRSA-IV on four acute hospital wards investigated using a combination of spa, dru and pulsed-field gel electrophoresis typing.

    LENUS (Irish Health Repository)

    Creamer, E

    2012-11-01

    The transmission of meticillin-resistant Staphylococcus aureus (MRSA) between individual patients is difficult to track in institutions where MRSA is endemic. We investigated the transmission of MRSA where ST22-MRSA-IV is endemic on four wards using demographic data, patient and environmental screening, and molecular typing of isolates. A total of 939 patients were screened, 636 within 72 h of admission (on admission) and 303 >72 h after admission, and 1,252 environmental samples were obtained. Isolates were typed by spa, dru and pulsed-field gel electrophoresis (PFGE) typing. A composite dendrogram generated from the three sets of typing data was used to divide isolates into \\'dendrogram groups\\' (DGs). Ten percent of patients (92\\/939) were MRSA-positive; 7 % (44\\/636) on admission and 16 % (48\\/303) >72 h after admission (p = 0.0007). MRSA was recovered from 5 % of environmental specimens (65\\/1,252). Most isolates from patients (97 %, 85\\/88) and the environment (97 %, 63\\/65) exhibited the ST22-MRSA-IV genotype. Four DGs (DG1, DG4, DG16 and DG17) accounted for 58 % of ST22-MRSA-IV isolates from patients. Epidemiological evidence suggested cross-transmission among 44\\/92 patients (48 %) but molecular typing confirmed probable cross-transmission in only 11 instances (13 %, 11\\/88), with the majority of cross-transmission (64 %; 7\\/11) occurring on one ward. In the setting of highly clonal endemic MRSA, the combination of local epidemiology, PFGE, spa and dru typing provided valuable insights into MRSA transmission.

  15. [Drug susceptibility and analysis using pulsed-field gel electrophoresis of Streptococcus pyogenes strains isolated from the patients with streptococcal toxic shock syndrome (STSS) in Japan].

    Science.gov (United States)

    Okuno, Rumi; Endoh, Miyoko; Shimojima, Yukako; Yanagawa, Yoshitoki; Morozumi, Satoshi; Oonaka, Kenji; Furuhata, Katsunori; Fukuyama, Masafumi

    2005-04-01

    Previously, we have performed T typing of Streptococcus pyogenes strains isolated from patients with streptococcal toxic shock syndrome (STSS) in Japan, and streptococcal pyrogenic exotoxin (SPE) typing for epidemiological examination. In this study, we conducted a drug sensitivity test using these strains, and investigated the results of gene analysis by pulse-field gel electrophoresis (PFGE) of S. pyogenes strains derived from patients with STSS, the patient's family, and patients other than those with STSS. To clarify the relationship between the host and bacterial factors, we investigated the association between clinical symptoms and T typing of the isolated strains/production of streptococcal pyrogenic exotoxin. There were no strains resistant to beta-lactams, and only 1 strain was resistant to multiple agents other than beta-lactams. The PFGE pattern of T1 type strains was classified into 2 ; the pattern was consistent between the strains derived from patients with STSS and those derived from the patient's family. The PFGE pattern of T3 type strains was classified into 5 (IV) ; Pattern I, which was most frequently observed, was detected in both the strains derived from patients with STSS/non-STSS. However, Patterns II and III were detected only in the strains derived from patients with non-STSS. Patterns IV and V were detected only in the strains derived from patients with STSS. When examining the association between clinical symptoms and bacterial factors, disseminated intravascular coagulation (DIC) was associated with T1-SPE B-producing strains, and pharyngitis was associated with T3-SPE A-producing strains. In the future, the relationship between the host and bacterial factors should be further investigated.

  16. Comparison of the DiversiLab repetitive element PCR system with spa typing and pulsed-field gel electrophoresis for clonal characterization of methicillin-resistant Staphylococcus aureus.

    Science.gov (United States)

    Babouee, B; Frei, R; Schultheiss, E; Widmer, A F; Goldenberger, D

    2011-04-01

    The emergence of methicillin-resistant Staphylococcus aureus (MRSA) has become an increasing problem worldwide in recent decades. Molecular typing methods have been developed to identify clonality of strains and monitor spread of MRSA. We compared a new commercially available DiversiLab (DL) repetitive element PCR system with spa typing, spa clonal cluster analysis, and pulsed-field gel electrophoresis (PFGE) in terms of discriminatory power and concordance. A collection of 106 well-defined MRSA strains from our hospital was analyzed, isolated between 1994 and 2006. In addition, we analyzed 6 USA300 strains collected in our institution. DL typing separated the 106 MRSA isolates in 10 distinct clusters and 8 singleton patterns. Clustering analysis into spa clonal complexes resulted in 3 clusters: spa-CC 067/548, spa-CC 008, and spa-CC 012. The discriminatory powers (Simpson's index of diversity) were 0.982, 0.950, 0.846, and 0.757 for PFGE, spa typing, DL typing, and spa clonal clustering, respectively. DL typing and spa clonal clustering showed the highest concordance, calculated by adjusted Rand's coefficients. The 6 USA300 isolates grouped homogeneously into distinct PFGE and DL clusters, and all belonged to spa type t008 and spa-CC 008. Among the three methods, DL proved to be rapid and easy to perform. DL typing qualifies for initial screening during outbreak investigation. However, compared to PFGE and spa typing, DL typing has limited discriminatory power and therefore should be complemented by more discriminative methods in isolates that share identical DL patterns.

  17. Comparison of the DiversiLab Repetitive Element PCR System with spa Typing and Pulsed-Field Gel Electrophoresis for Clonal Characterization of Methicillin-Resistant Staphylococcus aureus▿

    Science.gov (United States)

    Babouee, B.; Frei, R.; Schultheiss, E.; Widmer, A. F.; Goldenberger, D.

    2011-01-01

    The emergence of methicillin-resistant Staphylococcus aureus (MRSA) has become an increasing problem worldwide in recent decades. Molecular typing methods have been developed to identify clonality of strains and monitor spread of MRSA. We compared a new commercially available DiversiLab (DL) repetitive element PCR system with spa typing, spa clonal cluster analysis, and pulsed-field gel electrophoresis (PFGE) in terms of discriminatory power and concordance. A collection of 106 well-defined MRSA strains from our hospital was analyzed, isolated between 1994 and 2006. In addition, we analyzed 6 USA300 strains collected in our institution. DL typing separated the 106 MRSA isolates in 10 distinct clusters and 8 singleton patterns. Clustering analysis into spa clonal complexes resulted in 3 clusters: spa-CC 067/548, spa-CC 008, and spa-CC 012. The discriminatory powers (Simpson's index of diversity) were 0.982, 0.950, 0.846, and 0.757 for PFGE, spa typing, DL typing, and spa clonal clustering, respectively. DL typing and spa clonal clustering showed the highest concordance, calculated by adjusted Rand's coefficients. The 6 USA300 isolates grouped homogeneously into distinct PFGE and DL clusters, and all belonged to spa type t008 and spa-CC 008. Among the three methods, DL proved to be rapid and easy to perform. DL typing qualifies for initial screening during outbreak investigation. However, compared to PFGE and spa typing, DL typing has limited discriminatory power and therefore should be complemented by more discriminative methods in isolates that share identical DL patterns. PMID:21307215

  18. Comparison of automated repetitive-sequence-based polymerase chain reaction and spa typing versus pulsed-field gel electrophoresis for molecular typing of methicillin-resistant Staphylococcus aureus.

    Science.gov (United States)

    Church, Deirdre L; Chow, Barbara L; Lloyd, Tracie; Gregson, Daniel B

    2011-01-01

    Automated repetitive polymerase chain reaction (PCR) (DiversiLab, bioMérieux, St. Laurent, Quebec, Canada) and single locus sequence typing of the Staphylococcus protein A (spa) gene with spa-type assignment by StaphType RIDOM software were compared to pulsed-field gel electrophoresis (PFGE) as the "gold standard" method for methicillin-resistant Staphylococcus aureus (MRSA) typing. Fifty-four MRSA isolates were typed by all methods: 10 of known PFGE CMRSA type and 44 clinical isolates. Correct assignment of CMRSA type or cluster occurred for 47 of 54 (87%) of the isolates when using a rep-PCR similarity index (SI) of ≥95%. Rep-PCR gave 7 discordant results [CMRSA1 (3), CMRSA2 (1), CMRSA4 (1), and CMRSA10 (2)], and some CMRSA clusters were not distinguished (CMRSA10/5/9, CMRSA 7/8, and CMRSA3/6). Several spa types occurred within a single PFGE or repetitive PCR types among the 19 different spa types found. spa type t037 was shared by CMRSA3 and CMRSA6 strains, and CMRSA9 and most CMRSA10 strains shared spa type t008. Time to results for PFGE, repetitive PCR, and spa typing was 3-4 days, 24 h, and 48 h, respectively. The annual costs of using spa or repetitive PCR were 2.4× and 1.9× higher, respectively, than PFGE but routine use of spa typing would lower annual labor costs by 0.10 full-time equivalents compared to PFGE. Repetitive PCR is a good method for rapid outbreak screening, but MRSA isolates that share the same repetitive PCR or PFGE patterns can be distinguished by spa typing. Copyright © 2011 Elsevier Inc. All rights reserved.

  19. A comparison of non-typhoidal Salmonella from humans and food animals using pulsed-field gel electrophoresis and antimicrobial susceptibility patterns.

    Directory of Open Access Journals (Sweden)

    Carol H Sandt

    Full Text Available Salmonellosis is one of the most important foodborne diseases affecting humans. To characterize the relationship between Salmonella causing human infections and their food animal reservoirs, we compared pulsed-field gel electrophoresis (PFGE and antimicrobial susceptibility patterns of non-typhoidal Salmonella isolated from ill humans in Pennsylvania and from food animals before retail. Human clinical isolates were received from 2005 through 2011 during routine public health operations in Pennsylvania. Isolates from cattle, chickens, swine and turkeys were recovered during the same period from federally inspected slaughter and processing facilities in the northeastern United States. We found that subtyping Salmonella isolates by PFGE revealed differences in antimicrobial susceptibility patterns and, for human Salmonella, differences in sources and invasiveness that were not evident from serotyping alone. Sixteen of the 20 most common human Salmonella PFGE patterns were identified in Salmonella recovered from food animals. The most common human Salmonella PFGE pattern, Enteritidis pattern JEGX01.0004 (JEGX01.0003ARS, was associated with more cases of invasive salmonellosis than all other patterns. In food animals, this pattern was almost exclusively (99% found in Salmonella recovered from chickens and was present in poultry meat in every year of the study. Enteritidis pattern JEGX01.0004 (JEGX01.0003ARS was associated with susceptibility to all antimicrobial agents tested in 94.7% of human and 97.2% of food animal Salmonella isolates. In contrast, multidrug resistance (resistance to three or more classes of antimicrobial agents was observed in five PFGE patterns. Typhimurium patterns JPXX01.0003 (JPXX01.0003 ARS and JPXX01.0018 (JPXX01.0002 ARS, considered together, were associated with resistance to five or more classes of antimicrobial agents: ampicillin, chloramphenicol, streptomycin, sulfonamides and tetracycline (ACSSuT, in 92% of human and

  20. Molecular epidemiology of contagious bovine pleuropneumonia in Tanzania based on amplified fragment length polymorphism and pulsed-field gel electrophoresis analysis

    DEFF Research Database (Denmark)

    Kusiluka, L.J.M.; Ojeniyi, B.; Friis, N.F.

    2001-01-01

    . The strains were analysed fur variations in the EcoRI and Csp6I restriction sites in the genomic DNA using the amplified fragment length polymorphism (AFLP) technique, and variations in the BamHI restriction sites using pulscd-field gel electrophoresis (PFGE). Six AFLP I) pes were detected among the analysed...

  1. Methicillin Resistant Staphylococcus Aureus Typing with Pulsed-Field Gel Electrophoresis%耐甲氧西林金黄色葡萄球菌PFGE分型研究

    Institute of Scientific and Technical Information of China (English)

    王磊; 祁伟; 孔秀凤; 宋诗铎

    2011-01-01

    目的:检测不同医院耐甲氧西林金黄色葡萄球菌(MRSA)优势菌株是否相同.方法:用常规方法对从天津医科大学第二医院及武汉同济医院临床标本中分离的金黄色葡萄球菌进行鉴定,采用头孢西丁纸片扩散法及mecA基因检测筛选出MRSA.采用脉冲场凝胶电泳法(PFGE)进行分型,以了解不同地区两家医院的优势菌株是否相同.结果:共分离出金黄色葡萄球菌127株,MRSA 83株,其中天津56株,武汉27株.天津56株MRSA 临床株PFGE分型为15型27个亚型,以A1型为主;武汉27株MRSA临床株PFGE分型为6型12个亚型,以A2,A4型为主.结论:2家医院MRSA优势菌株并不相同,尚未发现MRSA流行菌株.%Objective: To study whether there was the same dominance strain of methicillin resistant staphylococcus aureus (MRSA) obtained from two hospitals. Methods: According to routine process, clinical strains were identified from Tongji Hospital in Wuhan and the Second Hospital of Tianjin Medical University. MRSA was screened through cefoxitin disc diffusion test and the detection of mecA gene. The clinical strains were typed with pulsed-field gel electrophoresis, and the prevalence strain was checked. Results: There were 127 staphylococcus aureus strains, 83 MRSA, in which 56 separated from Tianjin and 27 from Wuhan. Conclusion: There is no same type in the dominance strains from two regions. No epidemic strains of MRSA were found.

  2. Surveillance and characterisation by pulsed-field gel electrophoresis of Cronobacter spp. in farming and domestic environments, food production animals and retail foods.

    Science.gov (United States)

    Molloy, Catherine; Cagney, Claire; O'Brien, Stephen; Iversen, Carol; Fanning, Séamus; Duffy, Geraldine

    2009-12-31

    Cronobacter spp. (formally Enterobacter sakazakii) has been linked to illness in infants from contaminated powdered infant formula, however, there is limited information on the environmental sources and potential transmission routes of this pathogen. The aim of this study was to establish if food production animals (cattle, pigs), and the wider farm environment were playing a role in the transmission of Cronobacter spp. and also to assess the risk of cross contamination in the home where infant formula is prepared, from the presence of the pathogen on other foods and the general domestic environment. A wide range of samples (n=518) was collected at dairy farms, meat abattoirs, retail food stores and domestic environs and examined for the pathogen using an adapted ISO/DTS 22964 cultural protocol. The modified method included incubation at 42 degrees C instead of 44 degrees C and serial dilution of the enriched media prior to plating on Druggan-Forsythe-Iversen agar. Presumptive Cronobacter spp. colonies were confirmed by Real Time PCR targeting the dnaG on the MMS operon. All Cronobacter spp. isolated were speciated using biochemical tests, tested for resistance to 8 antibiotics and characterised using pulsed field gel electrophoresis. Cronobacter spp. was not recovered from cattle faeces, farm soil or trough water but isolates (n=33) were recovered from a variety of other sample types including cattle feed, pork and beef cuts, beef burgers and beef mince, green vegetables as well as organic breakfast cereals and domestic vacuum cleaner dust. The species recovered included C. Sakazakii (n=21), C. malonaticus (n=1) and C. turicensis (n=1). Of the 33 isolates 51% were resistant to Cephalothin but sensitive to all other 7 tested antibiotics. Sub-typing of the recovered isolates by PFGE showed considerable clonal diversity, though a number of persistent PFGE profiles were observed. In conclusion the study showed that Cronobacter spp. was not carried by food production

  3. Laboratory Investigation of Salmonella enterica serovar Poona Outbreak in California: Comparison of Pulsed-Field Gel Electrophoresis (PFGE) and Whole Genome Sequencing (WGS) Results

    Science.gov (United States)

    Kozyreva, Varvara K.; Crandall, John; Sabol, Ashley; Poe, Alyssa; Zhang, Peng; Concepción-Acevedo, Jeniffer; Schroeder, Morgan N.; Wagner, Darlene; Higa, Jeffrey; Trees, Eija; Chaturvedi, Vishnu

    2016-01-01

    Introduction: Recently, Salmonella enterica serovar Poona caused a multistate outbreak, with 245 out of 907 cases occurring in California. We report a comparison of pulsed-field gel electrophoresis (PFGE) results with whole genome sequencing (WGS) for genotyping of Salmonella Poona isolates. Methods: CA Salmonella Poona isolates, collected from July to August 2015, were genotyped by PFGE using XbaI restriction enzyme. WGS was done using Nextera XT library kit with 2x300 bp or 2x250 bp sequencing chemistry on the Illumina MiSeq Sequencer.  Reads were mapped to the de novo assembled serovar Poona draft genome (48 contigs, N50= 223,917) from the outbreak using CLCbio GW 8.0.2. The phylogenetic tree was generated based on hqSNPs calling. Genomes were annotated with CGE and PHAST online tools. In silico MLST was performed using the CGE online tool. Results: Human (14) and cucumber (2) Salmonella Poona isolates exhibited 3 possibly related PFGE patterns (JL6X01.0018 [predominant], JL6X01.0375, JL6X01.0778).  All isolates that were related by PFGE also clustered together according to the WGS. One isolate with a divergent PFGE pattern (JL6X01.0776) served as an outlier in the phylogenetic analysis and substantially differed from the outbreak clade by WGS. All outbreak isolates were assigned to MLST sequence type 447. The majority of the outbreak-related isolates possessed the same set of Salmonella Pathogenicity Islands with few variations. One outbreak isolate was sequenced and analyzed independently by CDC and CDPH laboratories; there was 0 SNP difference in results. Additional two isolates were sequenced by CDC and the raw data was processed through CDPH and CDC analysis pipelines. Both data analysis pipelines also generated concordant results.  Discussion: PFGE and WGS results for the recent CA Salmonella enterica serovar Poona outbreak provided concordant assignment of the isolates to the outbreak cluster. WGS allowed more robust determination of genetic

  4. Analysis of pulsed-field gel electrophoresis molecular subtyping of Shigella strains in Shenzhen%深圳市志贺菌脉冲场电泳分子分型分析

    Institute of Scientific and Technical Information of China (English)

    兰全学; 扈庆华; 石晓路; 王冰; 林一曼; 程锦泉; 张顺祥

    2008-01-01

    目的 分析深圳市2001-2006年分离志贺菌菌株之间的相关性,初步建立志贺菌的脉冲场电泳(pulsed-field gel electrophoresis,PFGE)分子分型监测网络.方法 55株志贺菌基因组DNA经Xba Ⅰ酶切,通过PFGE获得电泳图谱,利用BioNumerics软件对图谱进行聚类分析.结果 55株志贺菌被分为41种PFGE图谱,聚类分析显示32株细菌谱型属于同一个群,其余菌株谱型差异较大.结论 深圳地区存在遗传紧密相关的志贺菌流行克隆,也存在遗传不相关克隆.PFGE分子分型监测网络的建立,有助于细菌性痢疾的主动监测、暴发调查和传染源追踪.%Objective To analyze the genetic relations of Shigella isolated from Shenzhen in 2001-2006 and develop primary molecular subtyping surveillance network of Shigella. Methods Chromosomal DNAs from 55 isolated in agarose were digested with the restriction enzyme Xba Ⅰ , and then were analyzed by pulsed-field gel electrophoresis. Pulsed-field gel electrophoresis (PFGE) patterns were clustered using BioNumerics software. Results All 41 distinctive PFGE patterns were identified among 55 strains. 32 strains belonged to one cluster. Differences were observed in other strains. Conclusion Both genetic-related clones and non-related clones of Shigella existed in Shenzhen. The development of PFGE molecular subtyping surveillance network would contribute to the active surveillance, outbreak investigation and source tracking for Shigellosis.

  5. Effects of Combined Pulsed Electric Field and Heat Treatment on Texture Characteristics of Whey Protein Gels%脉冲电场协同加热对乳清蛋白凝胶质构特性的影响

    Institute of Scientific and Technical Information of China (English)

    金声琅; 殷涌光; 王莹

    2013-01-01

    By using whey protein isolate as the target, some treating conditions affecting the hardness, elasticity and water holding capacity of the whey protein gels were investigated by the single-factor experiments, among which the electric field strength, pulse numbers and heating temperature varied from 15 to 55 kV/cm, 2 to 8 and 50 to 90℃ , respectively. The research found that properties of the formed gel have shown significant change after being treated by the high intensity pulsed electric field. Compared with whey protein without effect from the high intensity pulsed electric field, the hardness, elasticity and water holding capacity of gel decreased when the electric field strength varied from 15 to 25 kV/cm, increased significantly when the electric field strength was 35 kV/cm, but decreased again when the electric field strength was 45 kV/cm. When the electric field strength was 35 kV/cm, the hardness, elasticity and water holding capacity of gel strengthened with the increase of pulse number, but the later amplification was not remarkable. When heating temperature was 80℃ , the hardness and elasticity of gel reached their best. The water holding capacity showed optimal performance when heating temperature was 70℃.%以乳清蛋白为研究对象,在电场强度15 ~ 55 kV/cm、脉冲数2~8个、水浴温度50~90℃范围内,通过单因素试验考察各因素对乳清蛋白硬度、弹性和保水性的影响.研究结果表明:乳清蛋白经高压脉冲电场作用后,所形成凝胶的性质有显著变化.与未受高压脉冲电场处理的对照样相比,凝胶硬度、弹性和保水性在电场强度15~25 kV/cm时降低,在电场强度35 kV/cm时显著提高,45 kV/cm时又降低.在电场强度35 kV/cm条件下,凝胶硬度、弹性和保水性随着脉冲数的增加而增强,但后期增幅变化不显著.凝胶硬度和弹性在水浴温度为80℃时最佳,保水性在水浴温度为70℃时最佳.

  6. NMR in pulsed magnetic field

    KAUST Repository

    Abou-Hamad, Edy

    2011-09-01

    Nuclear magnetic resonance (NMR) experiments in pulsed magnetic fields up to 30.4 T focused on 1H and 93Nb nuclei are reported. Here we discuss the advantage and limitation of pulsed field NMR and why this technique is able to become a promising research tool. © 2011 Elsevier Inc. All Rights Reserved.

  7. High-resolution genotyping of Listeria monocytogenes by fluorescent amplified fragment length polymorphism analysis compared to pulsed-field gel electrophoresis, random amplified polymorphic DNA analysis, ribotyping, and PCR-restriction fragment length polymorphism analysis

    DEFF Research Database (Denmark)

    Vogel, Birte Fonnesbech; Fussing, V.; Ojeniyi, B.

    2004-01-01

    of different origin. The AFLP technique was compared with three other molecular typing methods - ribotyping, random amplified polymorphic DNA analysis (RAPD), and pulsed-field gel electrophoresis (PFGE) - in terms of discriminatory ability. PCR-restriction fragment length polymorphism was included......The purpose of this study was to evaluate fluorescent amplified fragment length polymorphism (AFLP) analysis for the inter- and intraspecies differentiation of a collection of 96 strains of Listeria monocytogenes and 10 non- L. monocytogenes strains representing six other Listeria species...... for virulence gene allele characterization. The 96 L. monocytogenes strains were divided into two major clusters by AFLP fingerprinting at a similarity level of 82% in concordance with the results of PFGE, RAPD, and ribotyping. One main cluster consisted of all of the 24 L. monocytogenes hly allele 1 strains...

  8. Genetic Structure Change in Harvard Vaccine Strain of Clostridium Tetani for the Period of 1990 to 2010 by Pulsed-Field Gel Electrophoresis

    Directory of Open Access Journals (Sweden)

    Ahmad Sakhravi

    2013-07-01

    Full Text Available Background: PFGE facilitates the differential migration of large DNA fragments through agarose gel by constantly changing the direction of the electrical field during electrophoresis. Possibility of high difference between strains and repeatability make PFGE one of the strong molecular methods in study of bacterial strains in epidemiology. To identifying and DNA fingerprinting of vaccine strain of Clostridium tetani by PFGE technique. Also, possibility of genotyping profile changes in frequency of vaccine strain of C. tetani during the period of 1990 to 2011.Materials and Methods: The vaccine strain of C. tetani was provided by Razi Vaccine and Serum Research Institute in Karaj. The seeds were inoculated into Columbia blood agar and grown for 72 h. The cultures were incubated at 35°C in anaerobic conditions. The PFGE analyses were performed using genomic DNA digested with the restriction enzyme SmaI. The electrophoresis analyses were carried out on a CHEF DR III apparatus (Bio-Rad and band patterns obtained were then analyzed.Results: The PFGE profile obtained from vaccine strain during a period of more than two decades revealed no remarkable genetic changes and mutations. This type of analysis provides detailed data useful for surveillance of vaccine strains and isolates as well as for the selection of certain predominant profiles for further investigation.Conclusion: This study showed no considerable change in chromosomal genome of Harvard, the vaccine strain. It is therefore concluded that the vaccine produced by Razi Institute had evidently no alteration or modification in accordance to PFGE profile analysis during a period of more than two decades.

  9. Comparison of Virulence Gene Identification, Ribosomal Spacer PCR, and Pulsed-Field Gel Electrophoresis for Typing of Staphylococcus aureus Strains Isolated from Cases of Subclinical Bovine Mastitis in the United States.

    Science.gov (United States)

    Adkins, Pamela R F; Middleton, John R; Fox, Lawrence K

    2016-07-01

    Staphylococcus aureus is one of the most important pathogens causing contagious mastitis in dairy cattle worldwide. The objectives of this study were to determine if recently described S. aureus genotype B was present among previously characterized isolates from cases of bovine intramammary infection in the United States and to compare pulsed-field gel electrophoresis (PFGE) to the combination of ribosomal spacer PCR (RS-PCR) and virulence gene identification for typing of S. aureus strains. The hypothesis was that isolates that were previously characterized as contagious would be identified as genotype B and that the results of the two strain-typing methods would be comparable. Isolates were selected from a collection of S. aureus isolates from eight dairy farms. Mammary quarter milk somatic cell count (SCC) and N-acetyl-β-d-gluconaminidase (NAGase) activity data were known and used to evaluate strain pathogenicity. RS-PCR was performed with conventional gel electrophoresis, and PCR was used for toxin gene identification. RS-PCR patterns were associated with a specific virulence gene pattern, as previously reported. Five RS-PCR banding patterns were identified. None of the isolates were characterized as genotype B. No association between RS-PCR types and milk SCC was found; however, NAGase activity was significantly higher in milk from mammary glands infected with RS-PCR banding type 1 (RSP type 1) than in milk from those infected with RSP type 2. The discriminatory power values were 1.0 and 0.46 for PFGE and RS-PCR, respectively. These data suggest that genotype B may have a limited geographic distribution and that PFGE is more discriminatory than RS-PCR performed with conventional gel electrophoresis for typing of S. aureus isolates of bovine origin. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  10. Cryosurgery with pulsed electric fields.

    Science.gov (United States)

    Daniels, Charlotte S; Rubinsky, Boris

    2011-01-01

    This study explores the hypothesis that combining the minimally invasive surgical techniques of cryosurgery and pulsed electric fields will eliminate some of the major disadvantages of these techniques while retaining their advantages. Cryosurgery, tissue ablation by freezing, is a well-established minimally invasive surgical technique. One disadvantage of cryosurgery concerns the mechanism of cell death; cells at high subzero temperature on the outer rim of the frozen lesion can survive. Pulsed electric fields (PEF) are another minimally invasive surgical technique in which high strength and very rapid electric pulses are delivered across cells to permeabilize the cell membrane for applications such as gene delivery, electrochemotherapy and irreversible electroporation. The very short time scale of the electric pulses is disadvantageous because it does not facilitate real time control over the procedure. We hypothesize that applying the electric pulses during the cryosurgical procedure in such a way that the electric field vector is parallel to the heat flux vector will have the effect of confining the electric fields to the frozen/cold region of tissue, thereby ablating the cells that survive freezing while facilitating controlled use of the PEF in the cold confined region. A finite element analysis of the electric field and heat conduction equations during simultaneous tissue treatment with cryosurgery and PEF (cryosurgery/PEF) was used to study the effect of tissue freezing on electric fields. The study yielded motivating results. Because of decreased electrical conductivity in the frozen/cooled tissue, it experienced temperature induced magnified electric fields in comparison to PEF delivered to the unfrozen tissue control. This suggests that freezing/cooling confines and magnifies the electric fields to those regions; a targeting capability unattainable in traditional PEF. This analysis shows how temperature induced magnified and focused PEFs could be used to

  11. Cryosurgery with pulsed electric fields.

    Directory of Open Access Journals (Sweden)

    Charlotte S Daniels

    Full Text Available This study explores the hypothesis that combining the minimally invasive surgical techniques of cryosurgery and pulsed electric fields will eliminate some of the major disadvantages of these techniques while retaining their advantages. Cryosurgery, tissue ablation by freezing, is a well-established minimally invasive surgical technique. One disadvantage of cryosurgery concerns the mechanism of cell death; cells at high subzero temperature on the outer rim of the frozen lesion can survive. Pulsed electric fields (PEF are another minimally invasive surgical technique in which high strength and very rapid electric pulses are delivered across cells to permeabilize the cell membrane for applications such as gene delivery, electrochemotherapy and irreversible electroporation. The very short time scale of the electric pulses is disadvantageous because it does not facilitate real time control over the procedure. We hypothesize that applying the electric pulses during the cryosurgical procedure in such a way that the electric field vector is parallel to the heat flux vector will have the effect of confining the electric fields to the frozen/cold region of tissue, thereby ablating the cells that survive freezing while facilitating controlled use of the PEF in the cold confined region. A finite element analysis of the electric field and heat conduction equations during simultaneous tissue treatment with cryosurgery and PEF (cryosurgery/PEF was used to study the effect of tissue freezing on electric fields. The study yielded motivating results. Because of decreased electrical conductivity in the frozen/cooled tissue, it experienced temperature induced magnified electric fields in comparison to PEF delivered to the unfrozen tissue control. This suggests that freezing/cooling confines and magnifies the electric fields to those regions; a targeting capability unattainable in traditional PEF. This analysis shows how temperature induced magnified and focused

  12. Cryosurgery with Pulsed Electric Fields

    Science.gov (United States)

    Daniels, Charlotte S.; Rubinsky, Boris

    2011-01-01

    This study explores the hypothesis that combining the minimally invasive surgical techniques of cryosurgery and pulsed electric fields will eliminate some of the major disadvantages of these techniques while retaining their advantages. Cryosurgery, tissue ablation by freezing, is a well-established minimally invasive surgical technique. One disadvantage of cryosurgery concerns the mechanism of cell death; cells at high subzero temperature on the outer rim of the frozen lesion can survive. Pulsed electric fields (PEF) are another minimally invasive surgical technique in which high strength and very rapid electric pulses are delivered across cells to permeabilize the cell membrane for applications such as gene delivery, electrochemotherapy and irreversible electroporation. The very short time scale of the electric pulses is disadvantageous because it does not facilitate real time control over the procedure. We hypothesize that applying the electric pulses during the cryosurgical procedure in such a way that the electric field vector is parallel to the heat flux vector will have the effect of confining the electric fields to the frozen/cold region of tissue, thereby ablating the cells that survive freezing while facilitating controlled use of the PEF in the cold confined region. A finite element analysis of the electric field and heat conduction equations during simultaneous tissue treatment with cryosurgery and PEF (cryosurgery/PEF) was used to study the effect of tissue freezing on electric fields. The study yielded motivating results. Because of decreased electrical conductivity in the frozen/cooled tissue, it experienced temperature induced magnified electric fields in comparison to PEF delivered to the unfrozen tissue control. This suggests that freezing/cooling confines and magnifies the electric fields to those regions; a targeting capability unattainable in traditional PEF. This analysis shows how temperature induced magnified and focused PEFs could be used to

  13. Investigation of ultrasonic properties of MAGIC gels for pulse-echo gel dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Atkins, T J; Humphrey, V F; Duck, F A; Tooley, M A, E-mail: timothy.atkins@nhs.ne

    2010-11-01

    Ultrasound has been proposed as an alternative 3D method to read out dosimetric gels. The ultrasonic properties of MAGIC gel are investigated in relation to producing a dosimetry system based on a pulse-echo technique. The sound speed, attenuation coefficient, and density of MAGIC gel were measured over a range of temperatures and doses. A nonlinear relationship between ultrasonic attenuation and dose was observed, with the attenuation below 10 Gy being approximately constant. The sound speed was 1550.3 {+-} 1.5 m s{sup -1} at 25 {sup 0}C with a dose sensitivity of 0.14 {+-} 0.03 m s{sup -1} Gy{sup -1}; both properties changed with temperature and were 1535.4 {+-} 0.8 m s{sup -1} and -0.08 {+-} 0.01 m s{sup -1} Gy{sup -1} respectively at 15 {sup 0}C. The density also varied with temperature and dose, and was 1028.9 {+-} 0.3 kg m{sup -3} with a dose sensitivity of 0.178 {+-} 0.004 kg m{sup -3} Gy{sup -1} at 26 {sup 0}C. The characteristic acoustic impedance of MAGIC gel was calculated to be 1.596 x 10{sup 6} kg m{sup 2} s{sup -1} at 0 Gy and 25 {sup 0}C. The dose sensitivities measured indicate that changes to the characteristic acoustic impedance caused by irradiation are small, and therefore a reflector that has a similar characteristic acoustic impedance is required to maximise sensitivity of the pulse-echo technique. A suitable material has been developed and the reflection characteristics of the interface between MAGIC gel and the reflector are also temperature dependent. It is concluded that temperature management will be central to the development of any practical pulse-echo dosimetry system.

  14. Polymorphic Amplified Typing Sequences and Pulsed-Field Gel Electrophoresis Yield Comparable Results in the Strain Typing of a Diverse Set of Bovine Escherichia coli O157:H7 Isolates

    Directory of Open Access Journals (Sweden)

    Indira T. Kudva

    2012-01-01

    Full Text Available Polymorphic amplified typing sequences (PATS, a PCR-based Escherichia coli O157:H7 (O157 strain typing system, targets insertions-deletions and single nucleotide polymorphisms at XbaI and AvrII restriction enzyme sites, respectively, and the virulence genes (stx1, stx2, eae, hlyA in the O157 genome. In this study, the ability of PATS to discriminate O157 isolates associated with cattle was evaluated. An in-depth comparison of 25 bovine O157 isolates, from different geographic locations across Northwest United States, showed that about 85% of these isolates shared the same dendogram clade by PATS and pulsed-field gel electrophoresis (PFGE, irrespective of the restriction enzyme sites targeted. The Pearson’s correlation coefficient, r, calculated at about 0.4, 0.3, and 0.4 for XbaI-based, AvrII-based and combined-enzymes PATS and PFGE similarities, respectively, indicating that these profiles shared a good but not high correlation, an expected inference given that the two techniques discriminate differently. Isolates that grouped differently were better matched to their locations using PATS. Overall, PATS discriminated the bovine O157 isolates without interpretive biases or sophisticated analytical software, and effectively complemented while not duplicating PFGE. With its quick turnaround time, PATS has excellent potential as a convenient tool for early epidemiological or food safety investigations, enabling rapid notification/implementation of quarantine measures.

  15. Pulsed-field gel electrophoresis typing of Eschericia coli strains from samples collected before and after pivmecillinam or placebo treatment of uncomplicated community-acquired urinary tract infection in women

    DEFF Research Database (Denmark)

    Ejrnæs, K; Sandvang, D; Lundgren, Bettina

    2006-01-01

    The primary infecting Escherichia coli strains from 156 women with community-acquired uncomplicated urinary tract infection (UTI) randomized to pivmecillinam or placebo and the E. coli strains causing UTI at two follow-up visits were typed using pulsed-field gel electrophoresis (PFGE......). In the pivmecillinam treatment group PFGE showed that among patients having a negative urine culture at the first follow-up 77% (46/60) had a relapse with the primary infecting E. coli strain and 23% (14/60) had reinfection with a new E. coli strain at the second follow-up. Among patients having E. coli at the first...... follow-up PFGE showed that 80% (32/40) had persistence with the primary infecting E. coli strain, 15% (6/40) had reinfection with a new E. coli strain, and 5% (2/40) had different E. coli strains at the two follow-up visits (one had reinfection followed by relapse, and the other had persistence followed...

  16. Optimized Multilocus variable-number tandem-repeat analysis assay and its complementarity with pulsed-field gel electrophoresis and multilocus sequence typing for Listeria monocytogenes clone identification and surveillance.

    Science.gov (United States)

    Chenal-Francisque, Viviane; Diancourt, Laure; Cantinelli, Thomas; Passet, Virginie; Tran-Hykes, Coralie; Bracq-Dieye, Hélène; Leclercq, Alexandre; Pourcel, Christine; Lecuit, Marc; Brisse, Sylvain

    2013-06-01

    Populations of the food-borne pathogen Listeria monocytogenes are genetically structured into a small number of major clonal groups, some of which have been implicated in multiple outbreaks. The goal of this study was to develop and evaluate an optimized multilocus variable number of tandem repeat (VNTR) analysis (MLVA) subtyping scheme for strain discrimination and clonal group identification. We evaluated 18 VNTR loci and combined the 11 best ones into two multiplexed PCR assays (MLVA-11). A collection of 255 isolates representing the diversity of clonal groups within phylogenetic lineages I and II, including representatives of epidemic clones, were analyzed by MLVA-11, multilocus sequence typing (MLST), and pulsed-field gel electrophoresis (PFGE). MLVA-11 had less discriminatory power than PFGE, except for some clones, and was unable to distinguish some epidemiologically unrelated isolates. Yet it distinguished all major MLST clones and therefore constitutes a rapid method to identify epidemiologically relevant clonal groups. Given its high reproducibility and high throughput, MLVA represents a very attractive first-line screening method to alleviate the PFGE workload in outbreak investigations and listeriosis surveillance.

  17. Resistance genes, phage types and pulsed field gel electrophoresis pulsotypes in Salmonella enterica strains from laying hen farms in southern Italy.

    Science.gov (United States)

    Camarda, Antonio; Pugliese, Nicola; Pupillo, Antonia; Oliva, Marta; Circella, Elena; Dionisi, Anna Maria; Ricci, Antonia; Legretto, Marilisa; Caroli, Anna; Pazzani, Carlo

    2013-08-06

    Twenty-four Salmonella enterica isolates (13 serovar Enteritidis and 11 Typhimurium) isolated from 5,600 samples from intensive laying hen farms in Italy in 1998-2007 were characterized for antimicrobial resistance genes, pulsotype and phage type. Most of S. Typhimurium strains were pulsotype STYMXB.0147 (81.8%), phage type DT143 and resistant to sulfamethoxazole encoded by sul2. Two multidrug resistant (MDR) strains were identified. One strain, STYMXB.0061, was resistant to ampicillin (A), chloramphenicol (C), streptomycin (S), sulfamethoxazole (Su) and tetracycline (T) encoded by the Salmonella Genomic Island SGI1. The second MDR strain, STYMXB.0110, was resistant to SSuT encoded by sul1 and sul2, aadA1 and tet(C)-flanked by an IS26 element, respectively. The tet(C) gene has been reported to confer low levels of resistance and it has very rarely been detected in S. Typhimurium from poultry. In the current study, the MIC value (32 µg/mL) was consistent with the breakpoint (≥16 µg/mL) reported for Enterobacteriaceae. Most of the S. Enteritidis strains were resistant to Su (encoded by sul2). One MDR strain (ANxSSuT) was identified. With the exception of nalidixic acid (Nx), the resistances were respectively encoded by bla(TEM), strAB, sul2 and tet(A) harbored by an IncN conjugative plasmid. All isolates were pulsotype SENTXB.0001 with PT14b being the most prevalent identified phage type (57.1%). In Europe, SENTXB.0001 is the predominant PFGE profile from clinical cases and the identification of PT14b has steadily been on the increase since 2001. The findings presented in this study highlight the potential spread of S. Enteritidis phage types PT14b and S. Typhimurium DT143 in a field of particular relevance for zoonoses. Additional, the presence of resistance genes and genetic elements (conjugative plasmid and IS element) underlines the need to assess routinely studies in field, such as poultry farms, relevant fot the public health and suitable for the storage

  18. Resistance Genes, Phage Types and Pulsed Field Gel Electrophoresis Pulsotypes in Salmonella enterica Strains from Laying Hen Farms in Southern Italy

    Directory of Open Access Journals (Sweden)

    Anna Caroli

    2013-08-01

    Full Text Available Twenty-four Salmonella enterica isolates (13 serovar Enteritidis and 11 Typhimurium isolated from 5,600 samples from intensive laying hen farms in Italy in 1998–2007 were characterized for antimicrobial resistance genes, pulsotype and phage type. Most of S. Typhimurium strains were pulsotype STYMXB.0147 (81.8%, phage type DT143 and resistant to sulfamethoxazole encoded by sul2. Two multidrug resistant (MDR strains were identified. One strain, STYMXB.0061, was resistant to ampicillin (A, chloramphenicol (C, streptomycin (S, sulfamethoxazole (Su and tetracycline (T encoded by the Salmonella Genomic Island SGI1. The second MDR strain, STYMXB.0110, was resistant to SSuT encoded by sul1 and sul2, aadA1 and tet(C-flanked by an IS26 element, respectively. The tet(C gene has been reported to confer low levels of resistance and it has very rarely been detected in S. Typhimurium from poultry. In the current study, the MIC value (32 µg/mL was consistent with the breakpoint (³16 µg/mL reported for Enterobacteriaceae. Most of the S. Enteritidis strains were resistant to Su (encoded by sul2. One MDR strain (ANxSSuT was identified. With the exception of nalidixic acid (Nx, the resistances were respectively encoded by blaTEM, strAB, sul2 and tet(A harbored by an IncN conjugative plasmid. All isolates were pulsotype SENTXB.0001 with PT14b being the most prevalent identified phage type (57.1%. In Europe, SENTXB.0001 is the predominant PFGE profile from clinical cases and the identification of PT14b has steadily been on the increase since 2001. The findings presented in this study highlight the potential spread of S. Enteritidis phage types PT14b and S. Typhimurium DT143 in a field of particular relevance for zoonoses. Additional, the presence of resistance genes and genetic elements (conjugative plasmid and IS element underlines the need to assess routinely studies in field, such as poultry farms, relevant fot the public health and suitable for the storage

  19. Antibiotic resistance and pulsed-field gel electrophoresis patterns of Shigella sonnei isolates%宋内志贺菌耐药性及脉冲场凝胶电泳分子分型分析

    Institute of Scientific and Technical Information of China (English)

    章红红; 连伟刚; 王闻卿; 杨玲凤; 陈敏; 陈洪友; 张曦; 朱林英; 苏靖华; 傅慧琴; 黄红; 张勇琪

    2012-01-01

    目的 通过对宋内志贺菌菌株耐药性及脉冲场凝胶电泳(pulse-field gel electrophoresis,PFGE)分子分型分析,了解上海市浦东新区宋内志贺菌的耐药谱,并建立宋内志贺菌DNA指纹图谱数据库.方法 运用K-B法对34株宋内志贺菌株进行12种抗生素药敏试验,同时对菌株基因组DNA经限制性内切酶XbaⅠ酶切后进行PFGE分子分型,利用BioNumerics Version 5.10分析软件对图谱进行聚类分析.结果 34株宋内志贺菌菌株对链霉素、萘啶酸、甲氧嘧啶、复方新诺明耐药率为100%,对氨苄西林、庆大霉素、四环素耐药率分别为94.1%、91.2%和88.2%,对头孢他啶、头孢吡肟耐药率均为2.9%,对阿莫西林/克拉维酸、氯霉素、氧氟沙星为100%敏感.共获得13个PFGE带型,各带型间相似性系数在90%以上.相同PFGE带型内各菌株间药敏结果完全一致.J16X01.sh011为优势带型,不同时间、不同腹泻监测点之间存在完全相同PFCE条带.结论 宋内志贺菌多重耐药现象日趋严重,浦东新区存在遗传谱紧密相关的宋内志贺菌流行克隆系.%Objective To understand antibiotic resistance of Shigella sonnei and establish its DNA fingerprint database in Pudong district by conducting drug resistance test and pulsed-field gel electrophoresis (PFGE) molecular subtyping. Methods The drug resistance of 34 5. sonnei isolates to 12 antibiotics was conducted by K-B method, and the molecular subtyping of the isolates was done by PFGE after the digestion of restriction enzyme Xba I . Results The resistant rates of isolates to streptomycin, nalidixic acid, trimethoprim and sulfamethoxazole were 100% , and the resistant rate was 94. 1% to ampicillin, 91.2% to gentamicin, 88.2% to tetracycline and 2.9% to ceftazidime and cefepime, but they were all sensitive to amoxicillin, clavulanic acid, chloramphenicol and ofloxacin. All the isolates showed 13 PFGE patterns and similarity was more than 90%. The

  20. 脉冲场凝胶电泳在沙门菌鉴定中的应用%Application of pulsed-field gel electrophoresis in the identification of salmonella.

    Institute of Scientific and Technical Information of China (English)

    楼许柏; 马章林

    2011-01-01

    目的 探讨脉冲场凝胶电泳(PFGE)在沙门菌分型鉴定中的应用价值.方法 用PFGE方法对一起食物中毒分离出的68株肠炎沙门菌菌株进行分子分型.结果 180份标本经传统生化和血清分型鉴定出的68株肠炎沙门菌,通过PFGE分型后,均产生14条电泳条带,且分子量大小一致.通过BioNumerics软件的数据化处理分析,得到聚类关系树,68株肠炎沙门菌指纹图谱的相似性为100%,与H9812的相似性为65.65%.结论 PFGE是沙门菌分型鉴定的有效手段,可用于细菌性食物中毒传染源的追踪.%Objective To investigate the value of pulsed-field gel electrophoresis (PFGE) in the typing identification of salmonella. Methods PFGE method was used to 68 salmonella strains molecular typing identification isolated from food poisoning, Results 68 strains of salmonella enteritidis identified by traditional biochemical and the serotyplng from 180 specimens, after typing by PFGE, 14 electrophoretic bands were produced, and had the same molecular weight. The data was analyzed by BioNumerics software, clustering trees were obtained. The similarity of fingerprints was 100% in 68 salmonella enteritidis, 65.65% similarity with the H9812. Conclusion PFGE is an effective means in the typing identification of Salmonella, and can be used to trace the source of infection in bacterial food poisoning.

  1. Multilocus Variable-Number Tandem-Repeat Analysis, Pulsed-Field Gel Electrophoresis, and Antimicrobial Susceptibility Patterns in Discrimination of Sporadic and Outbreak-Related Strains of Yersinia enterocolitica

    Directory of Open Access Journals (Sweden)

    Skurnik Mikael

    2011-02-01

    Full Text Available Abstract Background We assessed the potential of multilocus variable-number tandem-repeat analysis (MLVA, pulsed-field gel electrophoresis (PFGE, and antimicrobial susceptibility testing for discriminating 104 sporadic and outbreak-related Yersinia enterocolitica (YE bio/serotype 3-4/O:3 and 2/O:9 isolates. MLVA using six VNTR markers was performed in two separate multiplex PCRs, and the fluorescently labeled PCR products were accurately sized on an automated DNA sequencer. Results MLVA discriminated 82 sporadic YE 3-4/O:3 and 2/O:9 strains into 77 types, whereas PFGE with the restriction enzyme NotI discriminated the strains into 23 different PFGE pulsotypes. The discriminatory index for a sporadic strain was 0.862 for PFGE and 0.999 for MLVA. MLVA confirmed that a foodborne outbreak in the city of Kotka, Finland in 2003 had been caused by a multiresistant YE 4/O:3 strain that was distinctly different from those of epidemiologically unrelated strains with an identical PFGE pulsotype. The multiresistance of Y. enterocolitica strains (19% of the sporadic strains correlated significantly (p = 0.002 with travel abroad. All of the multiresistant Y. enterocolitica strains belonged to four PFGE pulsotypes that did not contain any susceptible strains. Resistance to nalidixic acid was related to changes in codons 83 or 87 that stemmed from mutations in the gyrA gene. The conjugation experiments demonstrated that resistance to CHL, STR, and SUL was carried by a conjugative plasmid. Conclusions MLVA using six loci had better discriminatory power than PFGE with the NotI enzyme. MLVA was also a less labor-intensive method than PFGE and the results were easier to analyze. The conjugation experiments demonstrated that a resistance plasmid can easily be transferred between Y. enterocolitica strains. Antimicrobial multiresistance of Y. enterocolitica strains was significantly associated with travel abroad.

  2. Colonization of Bordetella pertussis clinical isolates that differ by pulsed field gel electrophoresis types in the lungs of naïve mice or mice immunized with the whole-cell pertussis vaccine used in Poland.

    Science.gov (United States)

    Polak, Maciej; Zawadka, Monika; Mosiej, Ewa; Rabczenko, Daniel; Augustynowicz, Ewa; Guiso, Nicole; Lutyńska, Anna

    2015-04-01

    The goal of our study was to compare the elimination of Bordetella pertussis clinical isolates that differ according to pulsed field gel electrophoresis (PFGE), serotypes and genes encoding virulence factors from the lungs of naïve mice or mice immunized with commercial diphtheria-tetanus-whole-cell pertussis vaccine used in Poland. When a mixture of four isolates, given in equal proportions and harboring different PFGE profiles, serotypes, and alleles encoding virulence factors, was used to infect non-immunized mice, a single isolate, characterized by PFGE type IVγ, Fim2 phenotype and ptxA1-prn2-tcfA2-fim2-1-ptxP1-ptxC1-fim3-1 alleles, was found to be significantly predominant compared to the others. This PFGE profile is commonly found in B. pertussis isolates circulating in some European countries since the late 1990s, confirming its high fitness. The Polish commercial whole-cell pertussis vaccine induced an immunity effective at eliminating the B. pertussis isolates from the lungs. However, the elimination of the isolate harboring PFGE type C profile, Fim2,3 phenotype and ptxA1-prn1-tcfA2-fim2-1-ptxP1-ptxC1-fim3-1 alleles was delayed as compared to the others, suggesting phenotypic differences with the other isolates and vaccine strains. Nevertheless, the same isolate, when challenged into mice in the defined mixture of strains, lost the competition with the others, as measured by lung colonization efficiency. This PFGE profile represents 15 % of the isolates circulating in Poland between 2001 and 2012.

  3. Characterisation of drug resistance of nosocomial ESBL-producing E. coli isolates obtained from a Turkish university hospital between 2009 and 2012 by pulsed field gel electrophoresis and antibiotic resistance tests.

    Science.gov (United States)

    Karagöz, Alper; Sunnetcioglu, Mahmut; Ceylan, Mehmet Resat; Bayram, Yasemin; Yalcin, Gozde; Kocak, Nadir; Suvak, Burak; Andac, Cenk A

    2016-01-01

    In this study, drug resistance of 28 ESBL-producing Escherichia coli isolates obtained from 144 patients hospitalized at the Yüzüncüyil University Hospital at Van (YUH), Turkey, between 2009 and 2012 were characterized by pulsed field gel electrophoresis and antibiotic susceptibility tests. Antibiotic resistance profile was determined by Phoenix automated system (BD, USA). The ratio of ESBL-producing E. coli strains was determined to be 19.4% (28 out of 144 E. coli isolates). It was determined that the anaesthesiology, paediatrics and thoracic medicine intensive care units in YUH were cross-contaminated between 2009 and 2012 by ESBL-producing E. coli strains, which is a sign of nosocomial infection in YUH. Analysis of PFGE results gave rise to two main PFGE profiles, profile-A with four subprofiles and profile-B with three subprofiles, where profile-A predominates over profile-B (14%). Comparison of the antibiotic resistance profile with the PFGE profile yielded similarities while some differences also exist due to either identical restriction enzyme cutting sites with slightly different genetic sequences in between the cutting sites or newly formed restriction enzyme cutting sites that do not affect antibiotic resistance genes. Enterobacteriaceae, particularly E. coli, have developed resistance in YUH by producing ESBLs against oxyimino and non-oxyimino cephalosporins, and penicillin-type antibiotics. Therefore, more effective antibiotics such as cefoxitin or cefoperazone-sulbactam should be used for the treatment of future nosocomial infections in YUH while hospital staff should take care with hygiene, such as hand washing.

  4. 中国肠炎沙门菌脉冲场凝胶电泳分子分型数据库的分析%Characterization of Salmonella enteritidis with pulsed-field gel electrophoresis in China

    Institute of Scientific and Technical Information of China (English)

    娄静; 刁保卫; 李杰; 阚飙; 闫梅英

    2013-01-01

    Objective To understand the pulsed-field gel electrophoresis (PFGE) patterns of the clinical isolates of Salmonella enteritidis and their epidemiological characteristics in China and provide evidence for the laboratory based detection of food borne diseases outbreak and response effort.Methods Molecular typing of 981 Salmonelle enteritidis strains isolated in 13 provinces from 2004 to 2012 were conducted according to PFGE protocol published on PulseNet and epidemiological analysis was conducted.Results The chromosomal DNA of 981 Salmonella enteritidis strains were digested with Xba Ⅰ restriction endonuclease and 126 PFGE patterns were observed.The discriminatory index (D) was 0.8336 for PFGE typing method.The predominate patterns of PFGE included JEGX01.CN0003,JEGX01.CN0001,JEGX01.CN0002,JEGX01.CN0005 and JEGX01.CN0016.Of 126 patterns,JEGX01.CN0003 、JEGX01.CN0001and JEGX01.CN0150 were related with outbreaks caused by Salmonella enteritidis.Common bands (±-0.8%) of 655 kbp,325 kbp,310 kbp,245 kbp,178 kbp and 110 kbp were found in the predominant patterns.Conclusion There were predominant PFGE patterns among the Salmonella enteritidis strains isolated in China,however,double or multiple endonucleotidases analysis of PFGE is necessary for outbreak detection due to the limited discriminatory power of single XbaⅠ digestion.%目的 了解近几年我国肠炎沙门菌临床分离株的流行病学及脉冲场凝胶电泳(PFGE)分子分型特点,为以实验室为基础的食源性疾病暴发的发现及疫情控制提供依据.方法 根据PulseNet公布的沙门菌PFGE分型方案,对2004-2012年分离自我国13个省(直辖市)的981株肠炎沙门菌进行流行病学及PFGE分子分型分析.结果 981株肠炎沙门菌经XbaⅠ酶切,PFGE获得126种带型,其分辨能力(D值)为0.8336.优势带型为JEGX01.CN0003、JEGX01.CN0001、JEGX01.CN0002、JEGX01.CN0005和JEGX01.CN0016.暴发相关带型是JEGX01.CN0003、JEGX01.CN0001和JEGX01.CN0150.肠炎沙

  5. Pulsed electric field increases reproduction.

    Science.gov (United States)

    Panagopoulos, Dimitris J

    2016-01-01

    Purpose To study the effect of pulsed electric field - applied in corona discharge photography - on Drosophila melanogaster reproduction, possible induction of DNA fragmentation, and morphological alterations in the gonads. Materials and methods Animals were exposed to different field intensities (100, 200, 300, and 400 kV/m) during the first 2-5 days of their adult lives, and the effect on reproductive capacity was assessed. DNA fragmentation during early- and mid-oogenesis was investigated by application of the TUNEL (Terminal deoxynucleotide transferase dUTP Nick End Labeling) assay. Sections of follicles after fixation and embedding in resins were observed for possible morphological/developmental abnormalities. Results The field increased reproduction by up to 30% by increasing reproductive capacity in both sexes. The effect increased with increasing field intensities. The rate of increase diminished at the strongest intensities. Slight induction of DNA fragmentation was observed exclusively in the nurse (predominantly) and follicle cells, and exclusively at the two most sensitive developmental stages, i.e., germarium and predominantly stage 7-8. Sections of follicles from exposed females at stages of early and mid-oogennesis other than germarium and stages 7-8 did not reveal abnormalities. Conclusions (1) The specific type of electric field may represent a mild stress factor, inducing DNA fragmentation and cell death in a small percentage of gametes, triggering the reaction of the animal's reproductive system to increase the rate of gametogenesis in order to compensate the loss of a small number of gametes. (2) The nurse cells are the most sensitive from all three types of egg chamber cells. (3) The mid-oogenesis checkpoint (stage 7-8) is more sensitive to this field than the early oogenesis one (germarium) in contrast to microwave exposure. (4) Possible therapeutic applications, or applications in increasing fertility, should be investigated.

  6. Directed cell movement in pulsed electric fields.

    Science.gov (United States)

    Franke, K; Gruler, H

    1994-01-01

    Human granulocytes exposed to pulsed electric guiding fields were investigated. The trajectories were determined from digitized pictures (phase contrast). The basic results are: (i) No directed response was induced by pulsed electric guiding fields having a zero averaged field. (ii) A directed response was induced by pulsed electric guiding fields having a non-zero averaged field. (iii) The directed response was enhanced for pulse sequences having a repetition time of 8 s. (iv) The lag-time between signal recognition and cellular response was 8-10 s. The results are discussed in the framework of a self-ignition model.

  7. Molecular typing of Laribacter hongkonggensis isolated in Guangxi province by pulsed-field gel electrophoresis%广西香港海鸥菌分离菌株脉冲场凝胶电泳分子分型研究

    Institute of Scientific and Technical Information of China (English)

    孙贵娟; 黄彦; 唐振柱; 卢桂宁; 苏伟东; 甘永新

    2011-01-01

    目的 探讨香港海鸥菌分子分型方法,了解广西水产品监测所分离的香港海鸥菌的相关性.方法 以NotⅠ限制性内切酶对2005年分离的香港海鸥菌酶切后进行脉冲电泳,用BioNumerics 5.1聚类分析获得电泳图谱.结果 7株香港海鸥菌分为6个分子型,其中从南宁分离的与从河池分离的2株香港海鸥菌高度同源,相似度达100%.结论 PFGE可应用于香港海鸥菌分子分型,有助于发现香港海鸥菌流行规律和传播途径,水鸟可能是香港海鸥菌传播环节的一种重要媒介.%Objective To study the molecular typing of Laribacter hongkonggensis by pulsed-field gel electrophoresis (PFCE) , and to find out the relationship of 7 strains of L. Hongkonggensis isolated from fishery products in Guangxi on 2005. Methods Total DNA of each isolate was digested with restriction enzyme Not I, and the DNA fingerprints were obtained by running PFGE. These fingerprints of different stains were compared and their relationship was investigated by BioNumerics 5. 1 clustering. Results Seven strains of L. Hongkonggensis were attributed to six PFGE pattern combinations. One isolate from Nanning and another one from Hechi were homologous with 100% similarity. Conclusion PFGE is an effective way for molecular typing L hongkonggensis and is helpful in discovering the epidemiology and transmission of this bacteria. Waterfowl might be an important medium in the spreading of L. Hongkonggensis.

  8. Molecular Typing of Salmonella Serotype O:4(B) by Using Pulsed-field Gel Electrophoresis%肠道沙门菌O:4(B)菌群脉冲场凝胶电泳分子分型

    Institute of Scientific and Technical Information of China (English)

    王红; 黄彦; 唐振柱; 孙贵娟; 李秀桂; 韦程媛

    2011-01-01

    为了明确2010年食源性疾病监测中分离的肠道沙门菌O:4(B)菌群的PFGE分子型别,探讨其多态性及其与分子流行病学关系,我们将分离获得的29株O:4(B)血清型沙门菌进一步鉴定培养,挑取单个菌落增菌,供试菌株基因组DNA用限制性内切酶Xba Ⅰ消化酶切后进行脉冲场凝胶电泳分型,所得结果用Bionumerics5.1软件进行聚类分析.实验结果表明,根据电泳指纹图谱,可将29株肠道沙门菌O:4(B)菌群分为24个PFGE型别,菌株间的相似值在56.31%~100%之间,同一血清型别的沙门菌有多个PFGE型别.脉冲场凝胶电泳对O:4(B)群沙门菌有较高的分型能力,可有效的应用于食物中沙门菌溯源分析及分子流行病学研究.%The objective of the present study was to document the polymorphism of PFGE molecular type of Salmonella enterica subsp. enterica serotype 0:4(B) which isolated from food-bome diseases and to explore theirs relationship of molecular epidemiological. In this research, 29 Salmonella stains were identified and the single colony was picked and enriched. Then the total genomic DNA of the isolates was digested with restriction enzyme Xba Ⅰ , and run pulsed-field gel electrophoresis (PFGE). The DNA fingerprints of different stains were analyzed by Bionumerics5.1 software to perform clustering. The DNA fingerprints of 29 Salmonella were belonged t0 24 PFGE pattem combinations. Similarity value of these strains was in the range of 56.31%-100%. One serotype Salmonella could be found several PFGE pattem combinations. The PFGE technology is a good method for molecular typing of Salmonella serotype 0:4(B) and could be effectively apply on tracing the suspected source of food contamination and investigate the food-poisoning and also study the molecular epidemiological relationship of different Salmonella stains.

  9. Characterization of Listeria monocytogenes isolates from cattle and ground beef by pulsed-field gel electrophoresis Caracterización de aislamientos de Listeria monocytogenes obtenidos de ganado y de carne molida de vacuno por electroforesis de campo pulsado

    Directory of Open Access Journals (Sweden)

    Claudia Foerster

    2012-09-01

    Full Text Available The aims of this study were to determine the occurrence of Listeria monocytogenes in cattle feces and ground beef, to characterize these strains by pulsed-field gel electrophoresis and to compare them to three listeria strains found in humans. Cattle from different origins (n = 250 and ground beef obtained from supermarkets (n = 40 were sampled. The results show low occurrence in cattle feces (0.4 % but a higher presence in ground beef (37 %. An important part of the ground beef strains (80 % had > 95 % similarity with a strain isolated from a human sporadic case and the ATCC 19115 used as control. The strain isolated from cattle feces had 93 % similarity to clone 009, previously associated with a listeriosis outbreak related to cheese. Cattle and ground beef can harbor virulent L. monocytogenes strains. Further studies in animals and animal products are needed to improve listeriosis control.Los objetivos de este estudio fueron determinar la presencia de Listeria monocytogenes en el ganado y en la carne molida de vacuno comercializada en Chile, caracterizar los aislados mediante electroforesis de campo pulsado y compararlos con los obtenidos en tres cepas que han producido listeriosis en humanos, en ese país. Se tomaron muestras de heces de bovinos (n = 250 y de carne molida obtenida en supermercados (n = 40. Se encontró una baja incidencia de este patógeno en las heces de bovinos (0,4 %; un solo animal, pero mayores porcentajes en la carne molida (37 %. Gran parte de las cepas encontradas en la carne molida (80 % mostraron una similitud mayor del 95 % con un caso esporádico de listeriosis y con la cepa de referencia ATCC 19115. La cepa aislada de bovino tuvo un 93 % de similitud con el clon 009, responsable de un brote asociado al consumo de queso, ocurrido en 2008. Se concluye que el ganado y la carne molida pueden albergar cepas virulentas de L. monocytogenes. Se necesita un mayor número de estudios en animales y en los productos que se

  10. Analysis of pulsed-field gel electrophoresis molecular subtyping and serotyping of Vibrio parahaemolyticus in food%食品中副溶血弧菌血清学分型与分子分型的研究

    Institute of Scientific and Technical Information of China (English)

    贺连华; 吴平芳; 陈妙玲; 王冰; 林爱红; 吕东月

    2011-01-01

    目的 分析深圳市2007~2010年监测食品中副溶血弧菌存在的优势血清型与基因型之间的相似性,初步建立深圳市食源性副溶血弧菌脉冲场凝胶电泳分子分型监测网络.方法 选择2007~2010年监测食品中分离出来的副溶血孤菌主要血清群(O1-O4)55株,基因组DNA经Sfi1酶切,通过脉冲场凝胶电泳PFGE获得图谱,利用BioNumerics 分析软件对图谱进行聚类分析.结果 相似性在90%以上的有15株,其中有9株相似性为100%,分别是2株O2:K28;1株O1:KUT与1株O4:K42;5株O3:K6,其余菌株谱型差异较大.结论 监测食品中分离的副溶血弧菌PFGE型别多,且相互之间关系分散.PFGE分子分型监测网络的建立,有助于食源性疾病发生时的主动监测,爆发调查和传染源追踪.%Objective To analyze the relationship between genotype and serotype of Vibrio parahaemolyticus isolated from food in Shenzhen from 2007 to 2010 and develop primary molecular subtyping surveillance network of Vibrio parahaemolyticus. Methods The 55 strains of Vibrio parahaemolylicus isolated from diarrhea patients containing important serotype O1-O4,chromosomal DNAs were digested with the restriction enzyme Sfil.and then were analyzed by pulsed-field gel electrophoresis. Results The similarity of the 15 strains was over 90% and 9 strains with 100% similarity including 2 strains O2:K28,1 strain 01:KUT and 1 strain O4:K42,5 strains O3:K6. Other strains showed prominent difference. Conclusion Various Vibrio parahaemolyticus patterns exist in food and the relationship is scattered. The development of PFGE molecular subtyping surveillance network would contribute to the surveillance,outbreak investigation and source tracking for Vibrio parahaemolyticus infection.

  11. 脉冲场凝胶电泳分子分型方法用于霍乱弧菌相关性分析%Correlation analysis of Vibrio cholerae by pulsed-field gel electrophoresis

    Institute of Scientific and Technical Information of China (English)

    于晓婕; 麻丽丹; 杨帆; 刁保卫

    2012-01-01

    目的 用脉冲场凝胶电泳(PFGE)分子分型方法,分析辽宁丹东和广东珠海两地区从水体和水产品中分离的霍乱弧菌之间的相关性.方法 对39株霍乱弧菌用内切酶Not I酶切DNA后进行PFGE分子分型,并在0.5×TBE电泳缓冲液中加入终浓度为3.8 mg/L的硫脲溶液电泳.结果 所有39株霍乱弧菌的基因组DNA显示出良好的分型结果,从朝鲜排污口、丹东鸭绿江水体中的鲫鱼、河蟹以及丹东排污口分离出的霍乱弧菌之间的相似度达到100%,说明这些产品之间应为同一个污染源;珠海的大头鱼和鳙鱼之间的相似度达到100%,说明这两者之间应为同一个污染源;珠海鲫鱼中检出的霍乱弧菌和鸭绿江水体中检出的霍乱弧菌之间的相似度达到88.4%,说明这两者之间可能为同一个污染源.结论 PFGE技术适用于霍乱弧菌环境样品分离菌株的相关性分析和传染源的追踪.%Objective To study the correlation of Vibrio cholerae by pulsed-field gel elec"rophoresis(PFGE) ,whieh were isolated from Liaoning Dandong and Guangdong Zhuhai in water body and seafood. Methods The chromosome DNA of 40 strains of Vibrio cholerae were digested by Not I enzyme and the PFGE were carried out, and 3.8mg/L finally concentration of Thiourea solution was added into the Thiourea0.5xTBE for Gel electrophoresis buffer. Results The chromosome DNA of 40 strains of Vibrio cholerae were typed well. The similarity of Vibrio cholerae which were isolated from sewage outfall of North Korea, Crucian Carp and river crab in Yalu river of Dandong, and sewage outfall of Dandong was up to 100%, it showed they were polluted by the same pollutant. The similarity of Vibrio cholerae which were isolated from Aspiorhynchus Laticeps and Aristichthys Nobilis in Zhuhai was up to 100%, it showed they were polluted by the same pollutant. The similarity of Vibrio cholerae which were isolated from Crucian Carp in Zhuhai and water body in Yalu river was

  12. On the Temperature Behavior of Pulse Propagation and Relaxation in Worms, Nerves and Gels.

    Directory of Open Access Journals (Sweden)

    Christian Fillafer

    Full Text Available The effect of temperature on pulse propagation in biological systems has been an important field of research. Environmental temperature not only affects a host of physiological processes e.g. in poikilotherms but also provides an experimental means to investigate the thermodynamic phenomenology of nerves and muscle. In the present work, the temperature dependence of blood vessel pulsation velocity and frequency was studied in the annelid Lumbriculus variegatus. The pulse velocity was found to vary linearily between 0°C and 30°C. In contrast, the pulse frequency increased non-linearly in the same temperature range. A heat block ultimately resulted in complete cessation of vessel pulsations at 37.2±2.7°C (lowest: 33°C, highest: 43°C. However, quick cooling of the animal led to restoration of regularly propagating pulses. This experimentally observed phenomenology of pulse propagation and frequency is interpreted without any assumptions about molecules in the excitable membrane (e.g. ion channels or their temperature-dependent behaviour. By following Einstein's approach to thermodynamics and diffusion, a relation between relaxation time τ and compressibility κ of the excitable medium is derived that can be tested experimentally (for κT ∼ κS. Without fitting parameters this theory predicts the temperature dependence of the limiting (i.e. highest pulse frequency in good agreement with experimental data. The thermodynamic approach presented herein is neither limited to temperature nor to worms nor to living systems. It describes the coupling between pulse propagation and relaxation equally well in nerves and gels. The inherent consistency and universality of the concept underline its potential to explain the dependence of pulse propagation and relaxation on any thermodynamic observable.

  13. High field rf superconductivity: to pulse or not to pulse

    Energy Technology Data Exchange (ETDEWEB)

    Campisi, I.E.

    1984-10-01

    Experimental data on the behavior of superconductors under the application of rf fields of amplitude comparable to their critical fields are sporadic and not always consistent. In many cases the field level at which breakdown in superconducting rf cavities should be expected has not been clearly established. Tests conducted with very short (approx. 1 ..mu..s) rf pulses indicate that in this mode of operation fields close to the critical values can be consistently reached in superconducting cavities without breakdown. The advantages and disadvantages of the pulsed method are discussed compared to those of the more standard continuous wave (cw) systems. 60 references.

  14. Pulsed electric field inactivation in a microreactor

    NARCIS (Netherlands)

    Fox, M.B.

    2006-01-01

    Pulsed electric fields (PEF) is a novel, non-thermal pasteurization method which uses short, high electric field pulses to inactivate microorganisms. The advantage of a pasteurization method like PEF compared to regular heat pasteurization is that the taste, flavour, texture and nutritional value ar

  15. Angular Spectrum Simulation of Pulsed Ultrasound Fields

    DEFF Research Database (Denmark)

    Du, Yigang; Jensen, Henrik; Jensen, Jørgen Arendt

    2009-01-01

    The optimization of non-linear ultrasound imaging should in a first step be based on simulation, as this makes parameter studies considerably easier than making transducer prototypes. Such a simulation program should be capable of simulating non-linear pulsed fields for arbitrary transducer...... geometries for any kind of focusing and apodization. The Angular Spectrum Approach (ASA) is capable of simulating monochromatic non-linear acoustic wave propagation. However, for ultrasound imaging the time response of each specific point in space is required, and a pulsed ASA simulation with multi temporal....... The RMS error of the pulses for all points in the simulated plane is 10.9%. The good agreement between ASA and Field II simulation for the pulsed ultrasound fields obtained in this paper makes it possible to expand Field II to non-linear pulsed fields....

  16. Magnetization reversal in ultrashort magnetic field pulses

    CERN Document Server

    Bauer, M; Fassbender, J; Hillebrands, B

    2000-01-01

    We report the switching properties of a thin magnetic film subject to an ultrashort, laterally localized magnetic field pulse, obtained by numerical investigations. The magnetization distribution in the film is calculated on a grid assuming Stoner-like coherent rotation within the grid square size. Perpendicularly and in-plane magnetized films exhibit a magnetization reversal due to a 4 ps magnetic field pulse. Outside the central region the pulse duration is short compared to the precession period. In this area the evolution of the magnetization during the field pulse does not depend strongly on magnetic damping and/or pulse shape. However, the final magnetization distribution is affected by the magnetic damping. Although the pulse duration is short compared to the precession period, the time needed for the relaxation of the magnetization to the equilibrium state is rather large. The influence of the different magnetic anisotropy contributions and the magnetic damping parameter enters into the magnetization ...

  17. Subspecies typing of Vibrio parahaemolyticus in aquatic products with pulsed-field gel electrophoresis%水产品中副溶血性弧菌脉冲场凝胶电泳分型

    Institute of Scientific and Technical Information of China (English)

    张昕; 汪琦; 张惠媛; 陈广全; 张捷

    2012-01-01

    Objective To assess subspecies typing of Vibrio parahaemolyticus strains from aquatic products with pulsed-field gel electrophoresis(PEGE). Methods A total of 80 selected isolates obtained from aquatic products were characterized with PFGE method. Genomic DNA was digested with restriction endonucleases NotI and Sfil. Results The isolates were grouped into 68 PFGE patterns by NotI and Sfil. Moreover, there were 70 PFGE patterns after compared with the results of the two restriction enzymes. The discrimination power of NotI was 78. 8% and that of Sfil was 76. 3% . Fourteen strains were from Canada four strain groups according to the Dice coefficient of 100% , thereinto, the Dice coefficient of four strains was 91. 8% and the Dice coefficient of ten strains was 93. 3% . Three strains form Norway and two strains from New Zealand belonged to 2 groups, with the Dice coefficient of 100%. There were no other same strains detected. Conclusion The results indicate that PFGE with both NotI and Sfil could be used in discriminant analysis for Vibrio parahaemolyticus, but NotI is more effective. The clustering analysis showes a clear disagreement among the strains and their sources. Furthermore, the strains with virulence genes are included in the same or contiguous clusters.%目的 采用脉冲场凝胶电泳(PFGE)对水产品中副溶血性弧菌进行分子分型.方法 采用PFGE技术,对80株分离自11个国家和中国浙江省和山东省的水产品中的副溶血性弧菌进行分子分型;基因组DNA用Not I和Sfi I2种酶进行消化.结果 Not I和Sfi I 2种内切酶均得到68种带型,综合系统树图中分成70种带型;Not I和Sfi I的分辨率分别为78.8%和76.3%;14株来自加拿大的菌株分聚成相似度100%的4组,其中有4株菌和10株菌分别聚成相似度91.8%和93.3%的2组;挪威和新西兰分别有3株和2株菌相似度为100%;其他国家的菌株无与本国相同的菌株.结论 2种酶均适合于

  18. 脉冲场凝胶电泳用于军团菌分型能力的评价%Evaluation of pulsed-field gel electrophoresis for Legionella subtyping

    Institute of Scientific and Technical Information of China (English)

    秦天; 任红宇; 周海健; 邵祝军

    2011-01-01

    目的 评价脉冲场凝胶电泳(PFGE)技术用于军团菌属不同种(Legionella species)以及不同血清型菌株的分型能力.方法 选用117株10个嗜肺军闭菌血清型,30种非嗜肺军团菌的参考菌株和我国环境分离菌株,采用Asc Ⅰ内切酶酶切,进行PFGE.从电泳条带的数量和分布、PFGE的分型力、分辨率和与流行病学资料的相关性等4个方面评价PFGE用于军团菌属不同血清型的嗜肺军团菌以及30个非嗜肺军团菌种分型的能力.结果 通过Asc Ⅰ酶切、PFGE 电泳后,所有血清型的嗜肺军团菌和17种非嗜肺军团菌能获得条带数量适合、且在电泳图谱上条带分布均匀,而另外13种非嗜肺军团菌株条带集中在小分量片段;PFGE能对所有117株选入实验的军团菌进行分析,分型力为100%;Asc Ⅰ-PFGE 将43株不同来源的各血清型嗜肺军团菌分成41个不同的璀,分型D值为0.9978,将30株非嗜肺军团各自分为不同的型;Asc Ⅰ-PFGE可以将相同来源的嗜肺军团菌和L micdadei军团菌分为相同或者相似的型,成簇聚类.结论 Asc Ⅰ-PFGE对所有血清型的嗜肺军团菌和17种非嗜肺军刚菌进行PFGE分型,能够获得高质量的电泳图谱,可成功用于嗜肺军团菌的流行病学调查.%Objective To evaluate the capability of pulsed-field gel electrophoresis (PFGE) for the subtyping of Legionella.Methods A total of 117 Legionella reference strains and environmental strains were analyzed by PFGE with Asc Ⅰ.Combined with the number and distributions of bands in the PFGE patterns, capability of subtyping, distinguishability of patterns and epidemiological information, we evaluated the capability of Asc Ⅰ-PFGE for Legionella subtyping.Results All Legionella pneumophila serotypes strains and 17 non-L.pneumophila strains showed high qualitative PFGE patterns; however,for other 13 non-L pneumophila serotypes strains, most of the PFGE bands were distributed with small weight.Asc

  19. Pulsed light and pulsed electric field for foods and eggs.

    Science.gov (United States)

    Dunn, J

    1996-09-01

    Two new technologies for use in the food industry are described. The first method discussed uses intense pulse of light. This pulsed light (PureBright) process uses short duration flashes of broad spectrum "white" light to kill all exposed microorganisms, including vegetative bacteria, microbial and fungal spores, viruses, and protozoan oocysts. Each pulse, or flash, of light lasts only a few hundred millionths of a second (i.e., a few hundred microseconds). The intensity of each flash of light is about 20,000 times the intensity of sunlight at the earth's surface. The flashes are typically applied at a rate of about one to tens of flashes per second. For most applications, a few flashes applied in a fraction of a second provide an effective treatment. High microbial kill can be achieved, for example, on the surfaces of packaging materials, on packaging and processing equipment, foods, and medical devices as well as on many other surfaces. In addition, some bulk materials such as water and air that allow penetration of the light can be sterilized. The results of tests to measure the effects of pulsed light on Salmonella enteritiditis on eggs are presented. The second method discussed uses multiple, short duration, high intensity electric field pulses to kill vegetative microorganisms in pumpable products. This pulsed electric field (or CoolPure) process can be applied at modest temperatures at which no appreciable thermal damage occurs and the original taste, color, texture, and functionality of products can be retained.

  20. Strong and superstrong pulsed magnetic fields generation

    CERN Document Server

    Shneerson, German A; Krivosheev, Sergey I

    2014-01-01

    Strong pulsed magnetic fields are important for several fields in physics and engineering, such as power generation and accelerator facilities. Basic aspects of the generation of strong and superstrong pulsed magnetic fields technique are given, including the physics and hydrodynamics of the conductors interacting with the field as well as an account of the significant progress in generation of strong magnetic fields using the magnetic accumulation technique. Results of computer simulations as well as a survey of available field technology are completing the volume.

  1. Salmonella surveillance in foods in Jiangsu province and the identification of molecular type with pulsed field gel electrophoresis%江苏省食品中沙门菌的监测及其脉冲场凝胶电泳分型研究

    Institute of Scientific and Technical Information of China (English)

    乔昕; 王燕梅; 沈赟; 符晓梅; 甄世祁

    2012-01-01

    目的:建立脉冲场凝胶电泳(PFGE)细菌分型方法,研究我省不同地区、不同种类食品中分离的沙门菌菌株间的同源关系.方法:对2008年从不同地区不同种类食品中分离出的21株沙门菌进行PFGE分子分型,所得结果用BioNumerics软件进行分析.结果:分离的沙门菌存在多种PFGE型别,扬州的生猪肉中分离的沙门菌存在一定的同源关系,2号、3号与4号菌株有88%同源.但无论是同一地区还是同种食品,都没有发现完全相同的PFGE分子型.结论:与其他分型方法相比,PFGE是一种具有高分辨率,高稳定性和高重复性的全新的细菌分子分型方法.在食品安全事件的处理中,它将成为通过细菌分子分型追踪传染源的快速有效方法.%Objective:To develop the method of typing bacteria by pulsed field gel electrophoresis, and study the homology of isolates from the various foods in Jiangsu province. Methods; 21 strains of salmonella were collected from various foods of different cities in Jiangsu province and typed with pulsed field gel electrophoresis, then analyzed using BioNumerics software. Results; There were many types of salmonella in 21 strains of isolates. The homology of salmonella isolated form raw pork of Yangzhou city reached 88%. No identical molecular type by pulsed field gel electrophoresis was found in 21 isolates. Conclusion; Pusled field gel electrophoresis method with the high resolution, stability and repeatability is rapid and effective in tracking the bacteria source in food safety incident.

  2. Wuhan pulsed high magnetic field center

    OpenAIRE

    Li, Liang; Peng, Tao; Ding, Honfa; Han, Xiaotao; Ding, Tonghai; Chen, Jin; Wang, Junfeng; Xie, Jianfeng; Wang, Shaoliang; Duan, Xianzhong; Wang, Cheng; Herlach, Fritz; Vanacken, Johan; Pan, Yuan

    2008-01-01

    Wuhan pulsed high magnetic field facility is under development. Magnets of bore sizes from 12 to 34 mm with the peak field in the range of 50 to 80 T have been designed. The pulsed power supplies consists of a 12 MJ, 25 kV capacitor bank and a 100 MVA/100 MJ flywheel pulse generator. A prototype 1 MJ, 25 kV capacitor bank is under construction. Five magnets wound with CuNb wire and copper wire reinforced internally with Zylon fiber composites and externally with stainless steel shells have be...

  3. Wuhan pulsed high magnetic field center

    OpenAIRE

    Li, Liang; Peng, Tao; Ding, Honfa; Han, Xiaotao; Ding, Tonghai; Chen, Jin; Wang, Junfeng; Xie, Jianfeng; Wang, Shaoliang; DUAN, Xianzhong; Wang, Cheng; Herlach, Fritz; Vanacken, Johan; Pan, Yuan

    2008-01-01

    Wuhan pulsed high magnetic field facility is under development. Magnets of bore sizes from 12 to 34 mm with the peak field in the range of 50 to 80 T have been designed. The pulsed power supplies consists of a 12 MJ, 25 kV capacitor bank and a 100 MVA/100 MJ flywheel pulse generator. A prototype 1 MJ, 25 kV capacitor bank is under construction. Five magnets wound with CuNb wire and copper wire reinforced internally with Zylon fiber composites and externally with stainless steel shells have be...

  4. Field mapping of ballistic pressure pulse sources

    Directory of Open Access Journals (Sweden)

    Rad Abtin Jamshidi

    2015-09-01

    Full Text Available Ballistic pressure pulse sources are used since late 1990s for the extracorporeal treatment of chronic Enthesitis. Newly indications are found in trigger-point-therapy for the treatment of musculoskeletal disorders. In both applications excellent results without relevant side effects were found in clinical trials. The technical principle of pressure pulse source is based on the same techniques used in air guns. A projectile is accelerated by pressurized air and hits the applicator with high kinetic energy. By this a compression wave travels through the material and induces a fast (4..5μs, almost singular pressure pulse of 2..10 MPa, which is followed by an equally short rarefaction phase of about the same amplitude. It is assumed that the pressure pulse accounts for the biomedical effects of the device. The slower inertial motion of the waveguide is damped by elastic stoppers, but still can be measured several micro seconds after the initial pressure pulse. In order to characterize the pressure pulse devices, field mapping is performed on several radial pressure pulse sources using the fiber optic hydrophone and a polyvinylidenfluorid (PVDF piezoelectric hydrophone. It could be shown that the current standard (IEC 61846 is not appropriate for characterization of ballistic pressure pulse sources.

  5. Magnetic Linear Birefringence Measurements Using Pulsed Fields

    CERN Document Server

    Berceau, Paul; Battesti, Remy; Rizzo, Carlo

    2011-01-01

    In this paper we present the accomplishment of the further step towards the vacuum magnetic birefringence measurement based on pulsed fields. After describing our BMV experiment, we report the calibration of our apparatus with nitrogen gas and we discuss the precision of our measurement giving a detailed error budget. Our best present vacuum sensitivity is 2.1x 10^-19 T^-2 per 5 ms magnetic pulse. We finally discuss the perspectives to reach our final goal.

  6. Rheological and textural properties of pulse starch gels

    Science.gov (United States)

    The properties of starch gels from black beans, chickpeas, lentils and navy beans were investigated. Differences were shown between starch sources, and effect of starch concentration was studied. Navy bean starch had the highest peak and final viscosities in pasting tests, while black bean starch h...

  7. Schwinger Pair Production in Pulsed Electric Fields

    CERN Document Server

    Kim, Sang Pyo; Ruffini, Remo

    2012-01-01

    We numerically investigate the temporal behavior and the structure of longitudinal momentum spectrum and the field polarity effect on pair production in pulsed electric fields in scalar quantum electrodynamics (QED). Using the evolution operator expressed in terms of the particle and antiparticle operators, we find the exact quantum states under the influence of electric pulses and measure the number of pairs of the Minkowski particle and antiparticle. The number of pairs, depending on the configuration of electric pulses, exhibits rich structures in the longitudinal momentum spectrum and undergoes diverse dynamical behaviors at the onset of the interaction but always either converges to a momentum-dependent constant or oscillates around a momentum-dependent time average after the completion of fields.

  8. Preliminary Studies on Pulsed Electric Field Breakdown of Lead Azide

    Science.gov (United States)

    1976-10-01

    1/2 OS CO ton NO. S3L TECHNICAL REPORT 4991 PRELIMINARY SUJDfES ON PULSED ELECTRIC FIELD BREAKDOWN OF LEAD AZIDE L AVRAMI M. BUMS D. DOWNS...Introduction Background A. Contact Effects B. Pulsed Electric Field Measurements Experimental A. Contact Effects B. Pulsed Electric Fields Discussion...B. Pulsed Electric Field Measurements The application of pulsed electric fields to lead azide does not exactly simulate the conditions experienced

  9. Comparison of a PCR-restriction fragment length polymorphism (PCR-RFLP) assay to pulsed-field gel electrophoresis to determine the effect of repeated subculture and prolonged storage on RFLP patterns of Shiga toxin-producing Escherichia coli O157:H7.

    Science.gov (United States)

    Shima, Kensuke; Wu, Yuluo; Sugimoto, Norihiko; Asakura, Masahiro; Nishimura, Kazuhiko; Yamasaki, Shinji

    2006-11-01

    In this study, we compared a recently developed PCR-restriction fragment length polymorphism (PCR-RFLP) assay with pulsed-field gel electrophoresis (PFGE) using three different Shiga toxin-producing Escherichia coli (STEC) strains to understand whether repeated subculture in vitro and prolonged storage at room temperature affect the RFLP patterns of STEC. The PFGE profiles of the STEC strains changed by 1 to 8 fragments after repeated subculture and prolonged storage; one strain was no longer clonal after repeated subculture compared to the original isolate according to the Tenover criteria. In contrast, RFLP patterns obtained by PCR-RFLP were identical after repeated subculture and prolonged storage. These data clearly indicate that the PCR-RFLP assay which is based on the diversity of region V, a regulatory region of Stx-phage, was not affected by repeated subculture and prolonged storage and is a more practical and reliable method for molecular typing of STEC strains.

  10. Pulsed Electric Field treatment of packaged food

    NARCIS (Netherlands)

    Roodenburg, B.

    2011-01-01

    Food manufacturers are looking for new preservation techniques that don’t influence the fresh-like characteristics of products. Non-thermal pasteurisation of food with Pulsed Electric Fields (often referred to as PEF) is an emerging technology, where the change of the food is less than with thermal

  11. Increase in local protein concentration by field-inversion gel electrophoresis

    Directory of Open Access Journals (Sweden)

    Paulus Aran

    2007-09-01

    Full Text Available Abstract Background Proteins that migrate through cross-linked polyacrylamide gels (PAGs under the influence of a constant electric field experience negative factors, such as diffusion and non-specific trapping in the gel matrix. These negative factors reduce protein concentrations within a defined gel volume with increasing migration distance and, therefore, decrease protein separation efficiency. Enhancement of protein separation efficiency was investigated by implementing pulsed field-inversion gel electrophoresis (FIGE. Results Separation of model protein species and large protein complexes was compared between FIGE and constant field electrophoresis (CFE in different percentages of PAGs. Band intensities of proteins in FIGE with appropriate ratios of forward and backward pulse times were superior to CFE despite longer running times. These results revealed an increase in band intensity per defined gel volume. A biphasic protein relative mobility shift was observed in percentages of PAGs up to 14%. However, the effect of FIGE on protein separation was stochastic at higher PAG percentage. Rat liver lysates subjected to FIGE in the second-dimension separation of two-dimensional polyarcylamide gel electrophoresis (2D PAGE showed a 20% increase in the number of discernible spots compared with CFE. Nine common spots from both FIGE and CFE were selected for peptide sequencing by mass spectrometry (MS, which revealed higher final ion scores of all nine protein spots from FIGE. Native protein complexes ranging from 800 kDa to larger than 2000 kDa became apparent using FIGE compared with CFE. Conclusion The present investigation suggests that FIGE under appropriate conditions improves protein separation efficiency during PAGE as a result of increased local protein concentration. FIGE can be implemented with minimal additional instrumentation in any laboratory setting. Despite the tradeoff of longer running times, FIGE can be a powerful protein

  12. Biofouling prevention with pulsed electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Abou-Ghazala, A.; Schoenbach, K.H.

    2000-02-01

    Temporary immobilization of aquatic nuisance species through application of short electric pulses has been explored as a method to prevent biofouling in cooling water systems where untreated lake, river, or sea water is used. In laboratory experiments, electrical pulses with amplitudes on the order of kilovolts/centimeter and submicrosecond duration were found to be most effective in stunning time in a temporal range from minutes to hours. The temporary immobilization is assumed to be caused by reversible membrane breakdown. This assumption is supported by results of measurements of the energy required for stunning. Based on the data obtained in laboratory experiments, field experiments in a tidal water environment have been performed. The flow velocity was such that the residence time of the aquatic nuisance species in the system was approximately half a minute. The results showed that the pulsed electric field method provides full protection against biofouling when pulses of 0.77 {micro}s width and 6 kV/cm amplitude are applied to the water at the inlet of such a cooling water system. Even at amplitudes of 1 kV/cm, the protection is still in the 90% range, at an energy expenditure of 1 kWh for the treatment of 60,000 gallons of water.

  13. High Field Pulse Magnets with New Materials

    Science.gov (United States)

    Li, L.; Lesch, B.; Cochran, V. G.; Eyssa, Y.; Tozer, S.; Mielke, C. H.; Rickel, D.; van Sciver, S. W.; Schneider-Muntau, H. J.

    2004-11-01

    High performance pulse magnets using the combination of CuNb conductor and Zylon fiber composite reinforcement with bore sizes of 24, 15 and 10 mm have been designed, manufactured and tested to destruction. The magnets successfully reached the peak fields of 64, 70 and 77.8 T respectively with no destruction. Failures occurred near the end flanges at the layer. The magnet design, manufacturing and testing, and the mode of the failure are described and analyzed.

  14. Pulsed photoelectric field emission from needle cathodes

    CERN Document Server

    Hernandez-Garcia, C

    2002-01-01

    Experiments have been carried out to measure the current emitted by tungsten needles with 1-mu m tip radius operated up to 50 kV. This corresponds to electric fields in the order of 10 sup 9 to 10 sup 1 sup 0 V/m. The needles were illuminated with 10-ns laser pulses at 532, 355 and 266 nm. The laser intensity was varied from 10 sup 1 sup 0 to 10 sup 1 sup 2 W/m sup 2 , limited by damage to the needle tip. The observed quantum efficiency depends on the wavelength and the electric field, approaching unity at the highest electric fields when illuminated at 266 nm. Peak currents up to 100 mA were observed in nanosecond pulses, corresponding to an estimated brightness of 10 sup 1 sup 6 A/m sup 2 sr. Since the current is controlled by the laser intensity, with only a weak voltage dependence, these cathodes can be used for infrared and ultraviolet tabletop free-electron lasers and other applications that demand short electron-beam pulses with high brightness.

  15. Field-Theoretic Studies of Nanostructured Triblock Polyelectrolyte Gels

    Science.gov (United States)

    Audus, Debra; Fredrickson, Glenn

    2012-02-01

    Recently, experimentalists have developed nanostructured, reversible gels formed from triblock polyelectrolytes (Hunt et al. 2011, Lemmers et al. 2010, 2011). These gels have fascinating and tunable properties that reflect a heterogeneous morphology with domains on the order of tens of nanometers. The complex coacervate domains, aggregated oppositely charged end-blocks, are embedded in a continuous aqueous matrix and are bridged by uncharged, hydrophilic polymer mid-blocks. We report on simulation studies that employ statistical field theory models of triblock polyelectrolytes, and we explore the equilibrium self-assembly of these remarkable systems. As the charge complexation responsible for the formation of coacervate domains is driven by electrostatic correlations, we have found it necessary to pursue full ``field-theoretic simulations'' of the models, as opposed to the familiar self-consistent field theory approach. Our investigations have focused on morphological trends with mid- and end-block lengths, polymer concentration, salt concentration and charge density.

  16. Optimization of pulsed-field gel electrophoresis for molecular typing of Brucella using Xba Ⅰ%布鲁杆菌XbaⅠ酶切脉冲场凝胶电泳基因分型方法的条件优化

    Institute of Scientific and Technical Information of China (English)

    赵鸿雁; 田国忠; 王衡; 姜海; 李兰玉; 杜小莉; 崔晶花; 朴东日

    2013-01-01

    Objective To optimize the protocol of pulsed-field gel electrophoresis(PFGE) to evaluate the applicability for molecular typing of Brucella using Xba].Methods Factors that influence PFGE including selecting restriction endonuclease from different manufacturers and pulse time were optimized.The bands were marked with their molecular weight and then analyzed with BioNumerics (Version 4.0,Applied Maths BVBA,Belgium) software.Results The Xba I from Promega Ltd was selected due to its better digestion effect.The best pulsed-field gel electrophoresis was performed in two phases for 21 h which included 16 h for pulse time of 0.5-8.0 s and 5 h for pulse time of 10.0-56.0 s; the angle of 120°,gradient of 6.0 V/cm,temperature of 14 ℃.The 6 Brucella species and 19 reference biovar strains were tested by optimized conditions of PFGE using Xba Ⅰ.The strains from four Brucella species which included Brucella abortus,Brucella melitensis,Brucella suis and Brucella ovis were clustered into four groups.But Brucella canis was classified in Brucella suis group.The Brucella neotomae was classified in Brucella abortus group.The results of clustering analysis by PFGE were similar to that of biotyping methods.Conclusions PFGE genotyping method using Xba I has good discriminatory power for molecular typing for Brucella.The optimized PFGE protocol is worthy of application.%目的 优化布鲁杆菌XbaⅠ酶切脉冲场凝胶电泳基因分型方法.方法 通过测试不同厂家生产的Xba I限制性内切酶,优化脉冲场凝胶电泳条件和脉冲时间,所得凝胶电泳图谱用BioNumerics V 4.0软件和UPGMA方法进行聚类分析,获得脉冲场凝胶电泳分型结果.结果 优化后的条件为:XbaI限制性内切酶为美国Promega公司产品;脉冲时间为21 h,包括第一脉冲时间0.5~8.0 s,16h,第二脉冲时间10.0~56.0 s,5h;电压为6.0 V/cm;电场夹角120°;电泳温度为14℃.利用优化后的脉冲场凝胶电泳条件对布鲁杆菌6个菌种19

  17. Investigation of a Salmonella enterica Serovars Weltevreden outbreak detected by active surveillance system via Pulsed Field Gel Electrophoresis%一起基于脉冲场凝胶电泳技术主动监测发现的韦太夫雷登沙门菌感染暴发调查

    Institute of Scientific and Technical Information of China (English)

    梁骏华; 柯碧霞; 黄琼; 黄熙; 卢玲玲; 邓小玲

    2013-01-01

    目的 通过对广东实验室沙门菌分子分型主动监测系统脉冲场凝胶电泳分子分型数据的分析,核实暴发,进行流行病学调查,探讨并制订预防控制措施.方法 采用描述流行病学方法,对暴发个案资料进行流行病学分析,采集涉事单位的食品和鸸鹋肛拭子样本进行沙门菌分离.结果 主动监测系统发现,广州市海珠区发生了一起由韦太夫雷登血清型沙门菌感染引起的食源性疾病暴发,发病5例,可疑食物载体为未煮熟的鸸鹋肉制食品.结论 这是广东省内首起基于脉冲场凝胶电泳技术建立的主动监测系统发现的食源性疾病暴发,应重视新型监测技术应用,以及由此带来的对目前政府部门应对暴发的协调机制的考验.%Objective To verify the suspected cluster cases detected by active surveillance system of Salmonella molecular subtyping via pulsed field gel electrophoresis through epidemiological investigation and to propose preventive and control measures. Methods We analyzed the distributions of time, location and demographic characteristics by descriptive epidemiology, and investigated the food exposure histories. Then we collected food samples and Emu' analswabs for Salmonella isolation. Results A foodborne disease outbreak of 5 cases induced by Salmonella enterica Serovars Weltevreden was detected by the active surveillance system in Haizhu district, Guangzhou city, and the undercooked Emu's meat product were the suspected food. Conclusion This is the first foodborne disease outbreak detected by active surveillance system via pulsed field gel electrophoresis in Guangdong Province, and the government should pay more attention to the application of the new technology and its consequent challenge on the outbreak response coordination mechanism.

  18. Pulsed-field magnetometry for rock magnetism

    Science.gov (United States)

    Kodama, Kazuto

    2015-07-01

    An improved method is proposed for measuring dynamic magnetizations of bulk volcanic rock samples induced by a pulsed-field of 0.7 T and a duration of 10 ms. The transient magnetization is measured by a sensing system that consists of a pair of inductive differential coils, an analog preamplifier and integrator, and a high-speed digital storage scope. The system was calibrated using a paramagnetic salt (Gd2O3) and was tested to different kinds of volcanic rocks with their magnetic properties well-documented previously. The results were comparable with those measured by a quasi-static method using a vibrating sample magnetometer, although there were small discrepancies in hysteresis parameters suggesting the time-dependence of the magnetic properties. The proposed system provides not only the magnetization over the short interval of a pulse but also the rapid (~3 ms) exponential decay after a pulse. The decay time constant was different among the samples under study, indicating the variations of their magnetic relaxation time. Although the present system is not sensitive enough to characterize varieties of natural samples including sediments, it has the potential as a versatile and convenient tool for rock magnetism.

  19. A Bonner Sphere Spectrometer for pulsed fields.

    Science.gov (United States)

    Aza, E; Dinar, N; Manessi, G P; Silari, M

    2016-02-01

    The use of conventional Bonner Sphere Spectrometers (BSS) in pulsed neutron fields (PNF) is limited by the fact that proportional counters, usually employed as the thermal neutron detectors, suffer from dead time losses and show severe underestimation of the neutron interaction rate, which leads to strong distortion of the calculated spectrum. In order to avoid these limitations, an innovative BSS, called BSS-LUPIN, has been developed for measuring in PNF. This paper describes the physical characteristics of the device and its working principle, together with the results of Monte Carlo simulations of its response matrix. The BSS-LUPIN has been tested in the stray neutron field at the CERN Proton Synchrotron, by comparing the spectra obtained with the new device, the conventional CERN BSS and via Monte Carlo simulations.

  20. Pulsed electric field assisted assembly of polyaniline

    Science.gov (United States)

    Kumar, Arun; Kazmer, David O.; Barry, Carol M. F.; Mead, Joey L.

    2012-08-01

    Assembling conducting polyaniline (PANi) on pre-patterned nano-structures by a high rate, commercially viable route offers an opportunity for manufacturing devices with nanoscale features. In this work we report for the first time the use of pulsed electric field to assist electrophoresis for the assembly of conducting polyaniline on gold nanowire interdigitated templates. This technique offers dynamic control over heat build-up, which has been a main drawback in the DC electrophoresis and AC dielectrophoresis as well as the main cause of nanowire template damage. The use of this technique allowed higher voltages to be applied, resulting in shorter assembly times (e.g., 17.4 s, assembly resolution of 100 nm). Moreover, the area coverage increases with the increase in number of pulses. A similar trend was observed with the deposition height and the increase in deposition height followed a linear trend with a correlation coefficient of 0.95. When the experimental mass deposited was compared with Hamaker’s theoretical model, the two were found to be very close. The pre-patterned templates with PANi deposition were subsequently used to transfer the nanoscale assembled PANi from the rigid templates to thermoplastic polyurethane using the thermoforming process.

  1. 猪链球菌脉冲场凝胶电泳分析方法的建立%Development of a protocol on pulsed field gel electrophoresis analysis for Streptococcus suis

    Institute of Scientific and Technical Information of China (English)

    王丽丽; 赵爱兰; 徐建国; 叶长芸; 许彦梅; 崔志刚; 景怀琦; 金东; 杜华茂; 张守印; 白雪梅

    2008-01-01

    Objective To develop a PFGE protocol for Streptococcus suis.Methods We developed and optimized a PFGE protocol for S.suis,in terms of plug preparation,choice of restriction endonucleases and optimized electrophoresis parameters.By analyzing the genome sequences of S.suis P1/7 with Mapdraw of DNAStar.we found three restriction enzymes,Swa Ⅰ,Sma Ⅰ and Apa Ⅰ,were more suitable than others.Results Analysis of 100 isolates of S.suis including 34 of 35 serotypes identified,59,53 and 43 patterns were obtained from Swa Ⅰ,Sma Ⅰ and Apa Ⅰ restriction,respectively.The enzyme Swa Ⅰ had the greatest power for discrimination ability.Conclusion By optimization of the protocol at various conditions,a rapid,reproducible,economic and practical PFGE method for S.suis was developed.%目的 建立一种可共享的猪链球菌脉冲场凝胶电泳分析(PFGE)方法.方法 利用PulseNet技术优化猪链球菌PFGE分子分型方法,提出新的分析方案,包括胶块的制备、内切酶的选择、电泳条件等.利用DNAStar的Mapdraw软件对猪链球菌基因组序列进行分析,发现在242种内切酶中,Swa Ⅰ、Sma Ⅰ、Apa Ⅰ种酶比较适合.结果 通过对34个血清型共100株菌的分析,发现使用Swa Ⅰ可获得59种带型,使用Sma Ⅰ可获得53种带型,使用Apa Ⅰ可获得43种带型.其中以Swa Ⅰ的分辨率最好.结论 提出猪链球菌的Swa Ⅰ PFGE分析方法,并对条件进行优化,较原方法所需时间短、图像清晰,更具有可重复性,基本具备推广的条件.

  2. Dynamic pulsed-field-gradient NMR

    CERN Document Server

    Sørland, Geir Humborstad

    2014-01-01

    Dealing with the basics, theory and applications of dynamic pulsed-field-gradient NMR NMR (PFG NMR), this book describes the essential theory behind diffusion in heterogeneous media that can be combined with NMR measurements to extract important information of the system being investigated. This information could be the surface to volume ratio, droplet size distribution in emulsions, brine profiles, fat content in food stuff, permeability/connectivity in porous materials and medical applications currently being developed. Besides theory and applications it will provide the readers with background knowledge on the experimental set-ups, and most important, deal with the pitfalls that are numerously present in work with PFG-NMR. How to analyze the NMR data and some important basic knowledge on the hardware will be explained, too.

  3. Deficiencies of active electronic radiation protection dosimeters in pulsed fields.

    Science.gov (United States)

    Ankerhold, U; Hupe, O; Ambrosi, P

    2009-07-01

    Nowadays nearly all radiation fields used for X-ray diagnostics are pulsed. These fields are characterised by a high dose rate during the pulse and a short pulse duration in the range of a few milliseconds. The use of active electronic dosimeters has increased in the past few years, but these types of dosimeters might possibly not measure reliably in pulsed radiation fields. Not only personal dosimeters but also area dosimeters that are used mainly for dose rate measurements are concerned. These cannot be substituted by using passive dosimeter types. The characteristics of active electronic dosimeters determined in a continuous radiation field cannot be transferred to those in pulsed fields. Some provisional measurements with typical electronic dosimeters in pulsed radiation fields are presented to reveal this basic problem.

  4. 肺炎克雷伯菌脉冲场凝胶电泳及多位点序列分型技术的联合应用%Molecular typing of Klebsiella pneumonia by pulse-field gel electrophoresis in combination with multilocus sequence typing

    Institute of Scientific and Technical Information of China (English)

    高源; 邵祝军; 张砺; 李马超; 黄成; 任红宇; 周海健; 朱兵清; 李倩; 王晓蕾

    2010-01-01

    Objective To type Klebsiella pneumonia through methods including pulse-field gel electrophoresis (PFGE) in combination with multilocus sequence typing. Methods Four selected different Eps, referring to the Standard Operating Procedure of PulseNet China, were used. The single colony of Klebsiella pneumonia was quantified after enriched culture. Embedding organisms in agarose and genome DNA were lysed with Proteinase K and then digested by restriction endonuclease Xba Ⅰ , to produce agarose gel. Fingerprint was obtained through PFGE and bands were marked with their molecular weights and then analyzed by BioNumerics software. Using MLST to analyze the strains that were highly similar, by PFGE typing Results By comparing the four results from each Eps, fk3 (switch time from 6s to 36s,total run time is 18.5 hours) seemed to be better than the others.59 strains of Klebsiella pneumonia were divided into 47 PFGE types and 19 PFGE clusters. The highly similar strains could be typed into ST-340、ST-342、ST-343、ST-344、ST-345 by MLST. Among them, ST-342、 ST-343、 ST-344、 ST-345 types were all new MLST types that were reported in China.Conclusion Highly similar Klebsiella pneumonias typed by PFGE could also be typed by MLST.%目的 联合使用脉冲场凝胶电泳(PFGE)及多位点序列分型(MLST)对肺炎克雷伯菌进行分型研究.方法 参照美国疾病预防控制中心及亚太地区PulseNet提供的PFGE相关标准化操作程序,优化相关电泳条件,对某儿童医院于2005-2006年分离到的59株菌分型分析,对其中高度相似性菌株进行MLST分型分析.结果 59株菌经PFGE分型分析,可分成47个PFGE型,19个PFGE群,具有高度相似性的菌株经MLST分型,其型别分别为ST-340、ST-342、ST-343、ST-344、ST-345,其中ST-342、ST-343、ST-344、ST-345为MLST数据库中中国新发现的ST型.结论 具有PFGE高度相似性的肺炎克雷伯菌可以通过MLST进一步确认或区分.

  5. Bag model for DNA migration during pulsed-field electrophoresis.

    OpenAIRE

    Chu, G

    1991-01-01

    A model for pulsed-field electrophoresis was developed by picturing large DNA as a deformable "bag" that (i) moves with limiting mobility in a continuous electric field, (ii) adopts an orientation aligned with the field direction, and (iii) reorients after a change in field direction in a size-dependent manner. The model correctly predicted the resolution of large DNA in a pulsed field including the surprising phenomena of mobility inversion, lateral band spreading, and improved resolution fo...

  6. Application of multiplex real-time PCR and pulse field gel electrophoresis in the etiological analysis of an outbreak of food-borne diseases%多重实时PCR及脉冲场凝胶电泳技术在一起食源性疾病暴发事件中的应用

    Institute of Scientific and Technical Information of China (English)

    黎燕; 俞骅; 张蔚; 钱小平; 郑伟; 汪皓秋

    2012-01-01

    Objective To assess the application of multiplex real-time PCR CMRP) and pulse field gel electrophoresis (PFGE) in the etiological analysis of food-borne infectious diseases. Methods MRP was used to amplify the Salmonella invasion protein A gene (invA), Escherichia coli heat-labile enterotoxin gene (elt), Shigella and enteroinvasive Escherichia invasion gene (ipaH) from 39 samples collected in a single outbreak. According to the result of MRP, routine isolation and culture were carried out and PFGE was used for genoty-ping of the isolates. Results 10 rectal swabs were found to be Salmonella invA positive and all strains were identified as Salmonella serotype Dublin. None of the samples were found to be gene elt and ipaH positive. PFGE revealed that all 10 Salmonella isolates had the same patterns. Conclusions MRP can help to determine the pathogen of food-borne infectious diseases and PFGE can be used for tracking the origin of these infections.%目的 探讨多重实时PCR (multiplex real-time PCR,MRP)和脉冲场凝胶电泳(pulse field gel electrophoresis,PFGE)技术在食源性疾病检测中的应用.方法 利用多重实时PCR技术对39份样本增菌培养物进行沙门菌侵袭蛋白A基因(invA)、肠产毒素性大肠埃希菌不耐热肠毒素基因(elt)、志贺菌和肠侵袭性大肠埃希菌侵袭力基因(ipaH)的检测,并根据多重实时PCR的结果有针对性的开展了常规的分离培养鉴定工作.应用PFGE对10株分离菌株进行分子分型.结果 10份患者肛拭检出沙门菌侵袭蛋白A(invA)基因,并从这10份样本中分离到10株都柏林血清型沙门菌.39份样本均未检出肠产毒素性大肠埃希菌不耐热肠毒素基因(elt)、志贺菌和肠侵袭性大肠埃希菌侵袭力基因(ipaH).10株都柏林血清型沙门菌PFGE条带完全一致.结论 多重实时PCR有助于提高细菌性食源性疾病的判明率,指导病原菌的常规分离培养,PFGE可用于细菌性食源性疾病的追踪溯源.

  7. Multilocus sequence typing and pulsed-field gel electrophoresis analysis of Salmonella Paratyphi A isolates from 2000 to 2008, China%中国2000-2008年间甲型副伤寒沙门菌脉冲场凝胶电泳和多位点序列分析

    Institute of Scientific and Technical Information of China (English)

    韩辉; 周海健; 崔志刚; 杜鹏程; 阚飙

    2010-01-01

    目的 分析我国2000-2008年间甲型副伤寒沙门菌流行株的分子分型及病原进化上的特征.方法 应用以Spe Ⅰ为限制性内切酶的脉冲场凝胶电泳(pulsed-field gel electrophoresis,PFGE)方法 和基于9个管家基因位点(aroC、thrA、hisD、purE、sucA、dnaN、hemD、adk和purA)的多位点序列分析(multilocus sequence typing,MLST)分型方法 ,对我国2000-2008年间分离自10个地区的118株甲型副伤寒沙门菌流行株进行分析.结果 应用PFGE方法 将118株甲型副伤寒沙门菌分为32个型,其中包含5株以上的优势PFGE带型有5种.而应用MLST方法 ,所有菌株只分出了2个序列分型(sequence type,ST),各菌株的管家基因序列高度保守,呈现高度克隆化.结论 中国2000-2008年间甲型副伤寒沙门菌菌株应用MLST这种分型方法 很难区分,MLST不适于甲型副伤寒沙门菌的暴发调查和流行病学监测.目前中国的甲型副伤寒是由高度克隆化的菌株引起全国范围的扩散 流行.随着年份的变迁,也积累了散在的变异.%Objective To analyze molecular and evolution characteristics of Salmonella Paratyphi A isolates from 2000 to 2008, China. Methods Using pulsed-field gel electrophoresis (PFGE) method with Spe Ⅰ restriction enzyme, and multilocus sequence typing (MLST) method based on housekeeping genes (aroC, thrA, hisD, purE, sucA, dnaN, hemD, adk, and purA), the genomic variations of 118 Salmonella Paratyphi A isolates from 10 regions during 2000 to 2008 were analyzed. Results Using PFGE method, 118 Salmonella Paratyphi A isolates were clustered into 32 PFGE patterns, and 5 patterns were predominant (5 isolates or above). However,only 2 MLST types were identified for all isolates with MLST method. Among all Salmonella Paratyphi A isolates, the sequences of housekeeping genes were highly conservative and showed a high degree of cloning. Conclusion For Chinese epidemic Salmonella Paratyphi A isolates during 2000 - 2008, MLST

  8. Weibel instability in the field of a short laser pulse

    Energy Technology Data Exchange (ETDEWEB)

    Grishkov, V. E.; Uryupin, S. A. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

    2013-03-15

    The growth rate of Weibel instability in a plasma interacting with a high-frequency pulse with a duration less or comparable with the electron mean free time is determined. The growth rate is shown to decrease with decreasing pulse duration. It is found that instability can develop after the short pulse is switched off and the generated magnetic field no longer affects electron motion in the high-frequency field.

  9. Field Theory for Coherent Optical Pulse Propagation

    CERN Document Server

    Park, Q H

    1997-01-01

    We introduce a new notion of "matrix potential" to nonlinear optical systems. In terms of a matrix potential $g$, we present a gauge field theoretic formulation of the Maxwell-Bloch equation that provides a semiclassical description of the propagation of optical pulses through resonant multi-level media. We show that the Bloch part of the equation can solved identically through $g$ and the remaining Maxwell equation becomes a second order differential equation with reduced set of variables due to the gauge invariance of the system. Our formulation clarifies the (nonabelian) symmetry structure of the Maxwell-Bloch equations for various multi-level media in association with symmetric spaces $G/H$. In particular, we associate nondegenerate two-level system for self-induced transparency with $G/H=SU(2)/U(1)$ and three-level $\\L $- or V-systems with $G/H = SU(3)/U(2)$. We give a detailed analysis for the two-level case in the matrix potential formalism, and address various new properties of the system including so...

  10. Pulsed Field Gel Electrophoresis and Genetic Diversity in Mycobacterium tuberculosis

    Directory of Open Access Journals (Sweden)

    Mohammad Poyeede

    2013-07-01

    Full Text Available AbstractBackground and objective: Tuberculosis is a considerable public health problem due to its high risk of person-to-person transmission, morbidity, and mortality especially in developing countries. According to the World Health Organization there is the emergence of multi-drug resistant M. tuberculosis and the association of TB with HIV has led to TB being declared. Molecular genotyping methods are important in detecting the dominance of transmission or reinfection in a population. During one year study genotyping of 100 of M. tuberculosis (M.t. isolates from patients referred to Pasteur Institute of Iran were accomplished with PFGE method. Material and methods: After identification of M.t. isolates and performing of antibiotic susceptibility test using standard methods, Melted Incert agarose and lysozyme were mixed with bacterial suspension to prepare PFGE plaques. After lyses and washing process the plaques digested with XbaI restriction enzyme. Finally the digested DNA fragments on 1% agarose with PFGE method were stained with ethidium bromide and analyzed with GelcomparII software.Results: Dendrogram of genetic diversity among 100 M.t. isolates were obtained in comparison of molecular weight marker and revealed two common types. Pulsotype A with 71 isolates and just one MDR and pulsotype B included 29 isolates and 3 MDR cases. No correlation between antibiotypes and pulsotypes were observed.Conclusion: It is very important to know about the existence of any clonal expansion of special M.t. genotypes with resistant strains. Our research shows 3 MDR isolates into the low incidence pulsotype B which could be an alarm for more accurate MDR-TB surveillance program. Probably such observed limited polymorphism may be due to conservation of restriction sites of XbaI enzyme. In order to investigate the genetic relatedness of isolates using other restriction enzymes and different molecular typing methods simultaneously were recommended.

  11. endotoxin genes of Bacillus thuringiensis by pulse field gel ...

    African Journals Online (AJOL)

    Owner

    method of naming these genes. So in 1989 they ... genomic DNA that all bacteria have, most of the B. ... METHOD. Isolation of B. thuringiensis subspecies from soil ... soil samples were treated by sodium acetate selective method. (Travers et ...

  12. 乌鲁木齐市水磨沟区霍乱弧菌分离株脉冲场凝胶电泳分析%Pulsed-field gel electrophoresis of Vibrio cholerae isolates from the Shuimogou District of the City of Urumqi,Xinjiang Uygur Autonomous Region

    Institute of Scientific and Technical Information of China (English)

    梁晓英; 樊于生

    2012-01-01

    [目的]了解新疆乌鲁木齐市水磨沟区相关年份霍乱弧菌分离株分子分型特征和遗传相关性.[方法]用脉冲场凝胶电泳(PFGE)对霍乱菌株进行分子分型,用BioNumericsV4.0软件UPGMA方法进行聚类分析.[结果]54株受试菌以NotI酶切后分为34个型,除1998023、2001009、2006010、1998160外,其他菌株带型高度相似(相似系数0.98),不同年份分离菌株型别不相同.[结论]乌鲁木齐水磨沟区霍乱弧菌可能含有多个克隆系,且分离出的霍乱弧菌为地方株.%Objective To ascertain the molecular and genetic correlation between characteristics of Vibrio cholerae isolates from Shuimogou, City Urumqi, Xinjiang in different years. Methods Pulsed field gel electrophoresis (PFGE) was used to molecularly type cholera strains, and cluster analysis was performed with UPGMA using BioNumericsV4. 0 software. Results Fifty-four strains were tested; Not I digestion resulted in 34 types that were highly similar (similarity coefficient of 0. 98) with the exception of 1998023, 2001009, 2006010, and 1998160; isolates from different years were of dissimilar types. Conclusion Vibrio cholerae from the Shuimogou District of Urumqi may consist of multiple clones, and Vibrio cholerae isolates may represent local strains.

  13. The effect of pulsed electric fields on carotenoids bioaccessibility

    NARCIS (Netherlands)

    Bot, Francesca; Verkerk, Ruud; Mastwijk, Hennie; Anese, Monica; Fogliano, Vincenzo; Capuano, Edoardo

    2018-01-01

    Tomato fractions were subjected to pulsed electric fields treatment combined or not with heating. Results showed that pulsed electric fields and heating applied in combination or individually induced permeabilization of cell membranes in the tomato fractions. However, no changes in β-carotene and

  14. Pulsed Electromagnetic Field Assisted in vitro Electroporation: A Pilot Study

    Science.gov (United States)

    Novickij, Vitalij; Grainys, Audrius; Lastauskienė, Eglė; Kananavičiūtė, Rūta; Pamedytytė, Dovilė; Kalėdienė, Lilija; Novickij, Jurij; Miklavčič, Damijan

    2016-09-01

    Electroporation is a phenomenon occurring due to exposure of cells to Pulsed Electric Fields (PEF) which leads to increase of membrane permeability. Electroporation is used in medicine, biotechnology, and food processing. Recently, as an alternative to electroporation by PEF, Pulsed ElectroMagnetic Fields (PEMF) application causing similar biological effects was suggested. Since induced electric field in PEMF however is 2–3 magnitudes lower than in PEF electroporation, the membrane permeabilization mechanism remains hypothetical. We have designed pilot experiments where Saccharomyces cerevisiae and Candida lusitaniae cells were subjected to single 100–250 μs electrical pulse of 800 V with and without concomitant delivery of magnetic pulse (3, 6 and 9 T). As expected, after the PEF pulses only the number of Propidium Iodide (PI) fluorescent cells has increased, indicative of membrane permeabilization. We further show that single sub-millisecond magnetic field pulse did not cause detectable poration of yeast. Concomitant exposure of cells to pulsed electric (PEF) and magnetic field (PMF) however resulted in the increased number PI fluorescent cells and reduced viability. Our results show increased membrane permeability by PEF when combined with magnetic field pulse, which can explain electroporation at considerably lower electric field strengths induced by PEMF compared to classical electroporation.

  15. Investigação de um surto causado por Cronobacter malonaticus em um hospital maternidade em Teresina, Piauí: caracterização e tipificação por eletroforese em gel de campo pulsado | Investigation of an outbreak caused by Cronobacter malonaticus in a Maternity Hospital in Teresina, Piauí: Characterization and typing by pulsed-field gel electrophoresis

    Directory of Open Access Journals (Sweden)

    Marcelo Luiz Lima Brandão

    2015-08-01

    relatedness among the clinical isolates. The samples of powdered infant formulas and pasteurized human milk that were ingested by the neonates were analyzed by different cultivation methods. The clinical strains were phenotypically characterized by the Vitek 2.0 system and conventional biochemical tests. To identify the genus and species, polymerase chain reaction targeting gluA and rpoB, respectively, was performed. The isolates were typed by pulsed-field gel electrophoresis using the restriction enzyme SpeI. No food sample showed contamination by Cronobacter spp. Three blood isolates were identified as C. malonaticus, two classified as biogroup 9 and one as biogroup 5, and were grouped in the same genotype. Our results suggest that the same clone was responsible for infection in three patients, but the source of contamination could not be identified.

  16. Strong-field short-pulse nondipole dynamics

    DEFF Research Database (Denmark)

    Dimitrovski, Darko; Førre, Morten; Madsen, Lars Bojer

    2009-01-01

    We present a quantitative investigation of strong-field short-pulse nondipole dynamics in laser-matter interactions. We find excellent agreement between ab initio numerical and analytic results obtained using the Magnus expansion. We show that in the short-pulse limit, ultrafast transfer and cont......We present a quantitative investigation of strong-field short-pulse nondipole dynamics in laser-matter interactions. We find excellent agreement between ab initio numerical and analytic results obtained using the Magnus expansion. We show that in the short-pulse limit, ultrafast transfer...

  17. Isolated Attosecond Pulses using a Detuned Second-harmonic Field

    Energy Technology Data Exchange (ETDEWEB)

    Merdji, Hamed; /Saclay /SLAC, PULSE; Auguste, Thierry; Boutu, Willem; Caumes, J.-Pascal; Carre, Bertrand; /Saclay; Pfeifer, Thomas; Jullien, Aurelie; Neumark, Daniel M.; Leone, Stephen R.; /UC, Berkeley /LBL, Berkeley

    2007-11-07

    Calculations are presented for the generation of an isolated attosecond pulse in a multicycle two-color strong-field regime. We show that the recollision of the electron wave packet can be confined to half an optical cycle using pulses of up to 40 fs in duration. The scheme is proven to be efficient using two intense beams, one producing a strong field at {omega} and the other a strong field detuned from 2{omega}. The slight detuning {delta}{omega} of the second harmonic is used to break the symmetry of the electric field over many optical cycles and provides a coherent control for the formation of an isolated attosecond pulse.

  18. Design of Pulsed Strong Magnetic Fields Generator and Preliminary Application

    Institute of Scientific and Technical Information of China (English)

    WEN Jun; QU Xue-min; WANG Xi-gang; LONG Kai-ping

    2015-01-01

    Objective: This paper aims to designing a pulsed strong magnetic fields generator. Methods: A large value capacitor was used to store electric energy, coil was used for producing magnetic fields, main control, circuit control charge, sampling, discharge, etc. Results: The generator provided a pulsed magnetic field with the ampli-tude of intensity from 0.1-2 T and variable time interval of pulse from 4 s-1 min. It was not only to be operated easily but also performed reliably. Conclusion:The generator will be applied in special clinical diagnosis, therapy and other fields.

  19. Room-temperature poling of PbTiO3/Pb(Zr,Ti)O3 sol-gel composite films by pulse discharge

    Science.gov (United States)

    Kouyama, Hikaru; Kibe, Taiga; Fujimoto, Shota; Namihira, Takao; Kobayashi, Makiko

    2016-07-01

    The PbTiO3/Pb(Zr,Ti)O3 (PT/PZT) sol-gel composite is a promising piezoelectric material because of its high piezoelectricity and temperature stability up to 360 °C. However, the poling of PT/PZT required high temperature owing to the high coercive field of PT, which made the poling of PT/PZT troublesome. In this research, conventional DC corona poling and pulse discharge at room temperature were attempted for PT/PZT samples. As a result, PT/PZT poled by pulse discharge generation at room temperature showed comparable ultrasonic responses to that poled by DC corona discharge generation at a high temperature. Therefore, room-temperature poling of PT/PZT was successfully carried out by pulse discharge, and poling time was markedly reduced from ˜15 min to 15 s.

  20. Experiencias en la vigilancia epidemiológica de agentes patógenos transmitidos por alimentos a través de electroforesis en campo pulsado (PFGE en el Perú Experiences in the epidemiological surveillance of foodborne pathogens by pulsed field gel electrophoresis (PFGE in Peru

    Directory of Open Access Journals (Sweden)

    María Luz Zamudio

    2011-03-01

    Full Text Available Las enfermedades transmitidas por alimentos (ETA y otras enfermedades entéricas infecciosas ocurren a menudo como brotes y son causa de morbilidad y mortalidad en todo el mundo. En el Perú, son un importante problema de salud pública y son causados por una gran variedad de agentes infecciosos. Para la investigación epidemiológica se utiliza una variedad de métodos de tipificación. Una de las herramientas más importantes en la subtipificación molecular de patógenos bacterianos es la técnica de la electroforesis en campo pulsado (PFGE, que es un método altamente resolutivo que permite la discriminación entre diferentes aislamientos bacterianos epidemiológicamente relacionados. El Instituto Nacional de Salud (INS del Perú integra las redes WHO Global Foodborne Infections Network y la Red PulseNet América Latina y Caribe, con quienes comparte los perfiles genéticos de las cepas patógenas aisladas, permitiendo comparar los genotipos de cepas semejantes halladas en diferentes países y reconocer la ocurrencia de brotes epidémicos en la región, fortaleciendo el sistema de vigilancia epidemiológica regional y generando una rápida respuesta conjunta entre países. Se presenta la experiencia de los dos últimos años sobre los avances en la utilización de estas herramientas estratégicas que nos ha permitido caracterizar patrones de genotipo de principales patógenos implicados en ETA a partir de aislamientos recuperados de la red de laboratorios del Perú.Foodborne diseases and other enteric infections often occur as outbreaks and cause morbidity and mortality all over the world. In Perú, they represent a serious public health problem, and are caused by a great variety of infectious agents. For epidemiological research, a wide array of typification methods are used. One of the most important tools for the molecular subtyping of bacterial pathogens is the Pulsed Field Gel Electrophoresis (PFGE, which is a highly precise method that

  1. [Mechanism of ablation with nanosecond pulsed electric field].

    Science.gov (United States)

    Cen, Chao; Chen, Xin-hua; Zheng, Shu-sen

    2015-11-01

    Nanosecond pulsed electric field ablation has been widely applied in clinical cancer treatment, while its molecular mechanism is still unclear. Researchers have revealed that nanosecond pulsed electric field generates nanopores in plasma membrane, leading to a rapid influx of Ca²⁺; it has specific effect on intracellular organelle membranes, resulting in endoplasmic reticulum injuries and mitochondrial membrane potential changes. In addition, it may also change cellular morphology through damage of cytoskeleton. This article reviews the recent research advances on the molecular mechanism of cell membrane and organelle changes induced by nanosecond pulsed electric field ablation.

  2. Pulse-train control of photofragmentation at constant field energy

    DEFF Research Database (Denmark)

    Tiwari, Ashwani Kumar; Henriksen, Niels Engholm

    2014-01-01

    We consider a phaselocked two-pulse sequence applied to photofragmentation in the weak-field limit. The two pulses are not overlapping in time, i.e., the energy of the pulse-train is constant for all time delays. It is shown that the relative yield of excited Br* in the nonadiabatic process: I + Br......*←IBr → I + Br, changes as a function of time delay when the two excited wave packets interfere. The underlying mechanisms are analyzed and the change in the branching ratio as a function of time delay is only a reflection of a changing frequency distribution of the pulse train; the branching ratio does...

  3. Analysis of typing by pulse-field gel electrophoresis of Listeria monocytogenes in Hangzhou during 2007~2011%2007年-2011年杭州地区食品中单核细胞增生李斯特菌PFGE型别分析

    Institute of Scientific and Technical Information of China (English)

    俞骅; 郑伟; 王艳; 金东; 斯国静; 潘劲草

    2013-01-01

    目的:研究2007年~2011年杭州地区食品中分离的单核细胞增生李斯特菌的血清型别与脉冲场凝胶电泳(PFGE)分子分型状况,建立区域PFGE数据库,为该菌的分子流行病学研究和食源性疾病溯源提供支持.方法:对56株单核细胞增生李斯特菌进行血清鉴定和PFGE分型,采用BioNumerics软件分析聚类关系.结果:56株菌分为5个不同的血清型和24个PFGE带型.1/2a(51.79%)和1/2c(30.36%)是优势血清型.P12是优势PFGE型别(16.07%).结论:杭州地区的单核细胞增生李斯特菌分子型别呈现多态性,用2种酶切综合分析能更好地了解单核细胞增生李斯特菌的遗传相关性及流行病学特征.%Objective:To analysis the serotypes and Pulsed-field gel electrophoresis (PFGE) characteristics of L.monocytogenes isolates in Hangzhou from 2007 to 2011 and to establish regional PFGE database which will support molecular epidemiology of L.monocytogenes and traceability of food-borne disease.Methods:56 L.monocytogenes strains were characterized by the serotyping and PFGE typing.Finger printing of each strain was analyzed by BioNumerics.Results:56 isolates were divided into five different serotypes and 24 PFGE patterns.The predominant serotypes were 1/2a (51.79%) and 1/2c (30.36%).The major PFGE pattern is P12 (16.07%).Conclusion:L.monocytogenes isolates in Hangzhou showed genetic diverse.PFGE typing combining two types of enzymes could help understanding genetic and epidemiological characteristics of L.monocytogenes.

  4. Successful suppression of magnetization precession after short field pulses

    OpenAIRE

    Bauer, Martin; Lopusnik, Radek; Fassbender, Jürgen; Hillebrands, Burkard; Dötsch, H.

    2000-01-01

    For the next generation of high data rate magnetic recording above 1 Gbit/s, a better understanding of the switching processes for both recording heads and media will be required. In order to maximize the switch-ing speed for such devices, the magnetization precession after the magnetic field pulse termination needs to be suppressed to a maximum degree. It is demonstrated experimentally for ferrite films that the appropriate adjustment of the field pulse parameters and/or the static applied f...

  5. The textural properties and microstructure of konjac glucomannan - tungsten gels induced by DC electric fields.

    Science.gov (United States)

    Wang, Lixia; Zhuang, Yuanhong; Li, Jingliang; Pang, Jie; Liu, Xiangyang

    2016-12-01

    Konjac glucomannan - tungsten (KGM-T) gels were successfully prepared under DC electric fields, in the presence of sodium tungstate. The textural properties and microstructure of the gels were investigated by Texture Analyzer, Rheometer and SEM. Based on the response surface methodology (RSM) results, the optimum conditions for KGM-T gel springiness is 0.32% sodium tungstate concentration, 0.54% KGM concentration, 24.66V voltage and 12.37min treatment time. Under these conditions, the maximum springiness value of KGM-T gel is 1.21mm. Steady flow measurement indicated that KGM-T gel showed characteristic non-Newtonian pseudoplastic behaviour, with low flow behaviour indexes in the shear thinning region. SEM demonstrated the porosity of the freeze-dried samples. These findings may pave the way to use DC electric fields for the design and development of KGM gels and to apply KGM gels for practical applications.

  6. 石家庄市集中空调系统水中嗜肺军团菌的脉冲场凝胶电泳指纹图谱分析%Pulsed-field Gel Electrophoresis Fingerprint Analysis of Legionella pneumophila in Water from Centralized Air Conditioning System in Shijiazhuang

    Institute of Scientific and Technical Information of China (English)

    郭玉梅; 秦丽云; 周吉坤; 王苋; 周海健

    2011-01-01

    Objective To analyze the molecular types of Legionella(L.)pneumophila strainswisolated from water in centralized air conditioning system (CACS) in Shijiazhuang and to develop the PulseNet -Shijiazhuang Database of L. Pneumophila. Methods Pulsed field gel electrophoresis (PFGE) was used to analyze L.pneumophila collected from water in CACS of Shijiazhuang in 2008. After digesting with Ascl , BioNumerics (Version 4) software was used to analyze the PFGE fingerprints. Cluster analysis was performed using the Marker H9812 calibration method. Results Twenty-five strains of L. Pneumophila were divided into 13 banding patterns,with SJZLP0006 (7 isolates) banding pattern strains accounted for 28% of bacterial strains. Cluster diagram showed all the serotype 1 strains similarity coefficients were 60%-100%; serum type 2-14 strains were 80% -100% . Conclusion L.pneumophUa strains isolated from water in CACS in Shijiazhuang are with polymorphism in distribution and high genetic variations and also have the characteristics of cloning.%目的 对石家庄市集中空调系统水中分离的25株嗜肺军团菌进行脉冲场凝胶电泳(PFGE)分析,初步建立石家庄市嗜肺军团菌的PFGE分型数据库.方法 采用PFGE技术,对2008年石家庄市集中空调系统水分离的嗜肺军团菌用AscI酶切,将PFGE图像用BioNumerics 4.0软件处理后,采用统一的分子量标准对照沙门菌(Braenderup)H9812菌株进行校准后进行聚类分析.结果 25株嗜肺军团菌的PFGE图谱共分为13种不同的PFGE带型,其中,LPA 16.SJZ0006(7株)带型最多,占分离菌株的28.0%.聚类分析结果显示,所有血清1型的菌株间相似性系数为60%~100%;血清2~14型的菌株间相似性系数为80%~100%.结论 本次从石家庄市集中空调系统水分离的嗜肺军团菌菌株呈多态性分布,基因组变异较大,同时也具有克隆化特征.

  7. Optimisation extraction of chondroitin sulfate from fish bone by high intensity pulsed electric fields.

    Science.gov (United States)

    He, Guidan; Yin, Yongguang; Yan, Xiaoxia; Yu, Qingyu

    2014-12-01

    High intensity pulsed electric fields (PEF) was used to extract chondroitin sulphate (CS) from fish bone. Results show that PEF extraction speed is much faster, and the content of CS is much higher compared with traditional methods. Variation of PEF parameters and the content of CS were determined by single factor experiments. The processing conditions were optimised by quadratic general rotary unitised design experiments. The maximum yield of 6.92 g/L was achieved under the following conditions: material-liquid ratio of 1:15 g/mL, electric field intensity of 16.88 kV/cm, pulse number of 9, and NaOH concentration of 3.24%. The purity of CS was analysed by agarose gel electrophoresis. CS purity was high, and the extract did not contain any other glycosaminoglycans. PEF can be widely used to extract CS with non-thermal performance, high speed, and low pollution.

  8. Development of advanced radiation monitors for pulsed neutron fields

    CERN Document Server

    AUTHOR|(CDS)2081895

    The need of radiation detectors capable of efficiently measuring in pulsed neutron fields is attracting widespread interest since the 60s. The efforts of the scientific community substantially increased in the last decade due to the increasing number of applications in which this radiation field is encountered. This is a major issue especially at particle accelerator facilities, where pulsed neutron fields are present because of beam losses at targets, collimators and beam dumps, and where the correct assessment of the intensity of the neutron fields is fundamental for radiation protection monitoring. LUPIN is a neutron detector that combines an innovative acquisition electronics based on logarithmic amplification of the collected current signal and a special technique used to derive the total number of detected neutron interactions, which has been specifically conceived to work in pulsed neutron fields. Due to its special working principle, it is capable of overcoming the typical saturation issues encountere...

  9. Time-varied magnetic field enhances transport of magnetic nanoparticles in viscous gel.

    Science.gov (United States)

    MacDonald, Cristin; Friedman, Gary; Alamia, John; Barbee, Kenneth; Polyak, Boris

    2010-01-01

    The potential of magnetic nanoparticles (MNPs) to deliver various forms of therapy has not been fully realized, in part due to difficulties in transporting the carriers through soft tissue to different target sites. The aim of this study was to demonstrate that transport of MNPs through a viscous gel can be controlled by a combined AC (time-varying) magnetic field and static field gradient. MNP velocity and transport efficiency were measured in a viscous gel at various settings of magnetic field and magnetite loadings. Combined application of an AC magnetic field with the static field gradient resulted in a nearly 30-fold increase in MNP transport efficiency in viscous gel for 30% (w/w) magnetite-loaded particles as compared with static field conditions. The 'oscillating' effect of an AC magnetic field greatly improves the ability to transport MNPs within soft media by decreasing the effective viscosity of the gel.

  10. Numeric modeling of synchronous laser pulsing and voltage pulsing field evaporation

    CERN Document Server

    Zhao, L; Houard, J; Blum, I; Delaroche, F; Vurpillot, F

    2016-01-01

    We have recently proposed an atom probe design based on a femtosecond time-resolved pump-probe setup. This setup unlocks the limitation of voltage pulsed mode atom probe thanks to the occurrence of local photoconductive switching effect . In this paper, we have used a numerical model to simulate the field evaporation process triggered by the synchronous two pulses. The model takes into account the local photoconductive effect and the temperature rise caused by the laser application and the voltage pulse distortion due to the RC effect.

  11. Effects of pulsed electric field on ULQ and RFP plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, M. [Iwate Univ., Morioka (Japan). Faculty of Engineering; Saito, K.; Suzuki, T. [and others

    1997-12-31

    Dynamo activity and self-organization processes are investigated using the application of pulsed poloidal and toroidal electric fields on ULQ and RFP plasmas. Synchronized to the application of the pulsed electric fields, the remarkable responses of the several plasma parameters are observed. The plasma has a preferential magnetic field structure, and the external perturbation activates fluctuation to maintain the structure through dynamo effect. This process changes the total dissipation with the variation of magnetic helicity in the system, showing that self organization accompanies an enhanced dissipation. (author)

  12. Skin Rejuvenation with Non-Invasive Pulsed Electric Fields

    Science.gov (United States)

    Golberg, Alexander; Khan, Saiqa; Belov, Vasily; Quinn, Kyle P.; Albadawi, Hassan; Felix Broelsch, G.; Watkins, Michael T.; Georgakoudi, Irene; Papisov, Mikhail; Mihm, Martin C., Jr.; Austen, William G., Jr.; Yarmush, Martin L.

    2015-05-01

    Degenerative skin diseases affect one third of individuals over the age of sixty. Current therapies use various physical and chemical methods to rejuvenate skin; but since the therapies affect many tissue components including cells and extracellular matrix, they may also induce significant side effects, such as scarring. Here we report on a new, non-invasive, non-thermal technique to rejuvenate skin with pulsed electric fields. The fields destroy cells while simultaneously completely preserving the extracellular matrix architecture and releasing multiple growth factors locally that induce new cells and tissue growth. We have identified the specific pulsed electric field parameters in rats that lead to prominent proliferation of the epidermis, formation of microvasculature, and secretion of new collagen at treated areas without scarring. Our results suggest that pulsed electric fields can improve skin function and thus can potentially serve as a novel non-invasive skin therapy for multiple degenerative skin diseases.

  13. Pulsed electric field reduces the permeability of potato cell wall.

    Science.gov (United States)

    Galindo, Federico Gómez; Vernier, P Thomas; Dejmek, Petr; Vicente, António; Gundersen, Martin A

    2008-05-01

    The effect of the application of pulsed electric fields to potato tissue on the diffusion of the fluorescent dye FM1-43 through the cell wall was studied. Potato tissue was subjected to field strengths ranging from 30 to 500 V/cm, with one 1 ms rectangular pulse, before application of FM1-43 and microscopic examination. Our results show a slower diffusion of FM1-43 in the electropulsed tissue when compared with that in the non-pulsed tissue, suggesting that the electric field decreased the cell wall permeability. This is a fast response that is already detected within 30 s after the delivery of the electric field. This response was mimicked by exogenous H2O2 and blocked by sodium azide, an inhibitor of the production of H2O2 by peroxidases. (c) 2007 Wiley-Liss, Inc.

  14. Production of pulsed electric fields using capacitively coupled electrodes

    Science.gov (United States)

    Kendall, B. R. F.; Schwab, F. A. S.

    1980-01-01

    It is shown that pulsed electric fields can be produced over extended volumes by taking advantage of the internal capacitances in a stacked array of electrodes. The design, construction, and performance of practical arrays are discussed. The prototype arrays involved fields of 100-1000 V/cm extending over several centimeters. Scaling to larger physical dimensions is straightforward.

  15. Microscopic Faraday rotation measurement system using pulsed magnetic fields.

    Science.gov (United States)

    Egami, Shigeki; Watarai, Hitoshi

    2009-09-01

    Microscopic Faraday rotation measurement system using a pulsed magnetic field has been constructed, which can be applied to micron sized diamagnetic and paramagnetic materials. A pulsed magnetic coil could generate a maximum magnetic flux density of about 12 T. The performance of the microscopic Faraday rotation apparatus was demonstrated by the measurement of the Verdet constant V of a polystyrene particle, after the calibration of the pulsed magnetic flux density using a glass plate as a standard material. Also, the magneto-optical rotation dispersion of some diamagnetic substances have been measured and analyzed with V=alambda(-2)+b. The values of a and b were compared to their magnetic susceptibilities.

  16. Investigation of an angular spectrum approach for pulsed ultrasound fields

    DEFF Research Database (Denmark)

    Du, Yigang; Jensen, Henrik; Jensen, Jørgen Arendt

    2013-01-01

    sources are compared to the Field II simulated and hydroph one measure dpulses, respectively. The total relative root mean squar e(RMS)errors of the pulsed ASA are investigated by using different time-point, zero-padding factors, spatial sampling interval and temporal sampling frequency in the sim ulation....... Optim al parameters for the ASA are found in the simulation .The RMS error of the ASA simulation is reduced from 10.9% to 2.4% for the optimal parameters when comparing to Field II simulation s. The comparison between the ASA calculated and measured pulses are illustrated and the corresponding RMS error......An Angular Spectrum Approach (ASA)is formulated and employed to simulate linear pulsed ultra sound fields for high bandwidth signals. Ageometrically focused piston transducer is used as the acoustic source. Signals are cross-correlated to findthe true sound speed during the measurement to make...

  17. Penetration dynamics of a magnetic field pulse into high-? superconductors

    Science.gov (United States)

    Meerovich, V.; Sinder, M.; Sokolovsky, V.; Goren, S.; Jung, G.; Shter, G. E.; Grader, G. S.

    1996-12-01

    The penetration of a magnetic field pulse into a high-0953-2048/9/12/004/img9 superconducting plate is investigated experimentally and theoretically. It follows from our experiments that the threshold of penetration increases with increasing amplitude and/or decreasing duration of the applied pulse. The penetrating field continues to grow as the applied magnetic field decreases. The peculiarities observed are explained in the framework of the extended critical state model. It appears that the deviations from Bean's classical critical state model are characterized by a parameter equal to the square of the ratio of plate thickness to skin depth. The applicability of the classical critical state model is restricted by the condition that this parameter is much less than 1. This condition is also the criterion for the applicability of pulse methods of critical current measurements.

  18. Heat pulse propagation in chaotic 3-dimensional magnetic fields

    CERN Document Server

    del-Castillo-Negrete, D

    2014-01-01

    Heat pulse propagation in $3$-D chaotic magnetic fields is studied by solving the parallel heat transport equation using a Lagrangian-Green's function (LG) method. The LG method provides an efficient and accurate technique that circumvents limitations of finite elements and finite difference methods. The main two problems addressed are: (i) The dependence of the radial transport on the magnetic field stochasticity (controlled by the amplitude of the perturbation, $\\epsilon$); and (ii) The role of reversed shear configurations on pulse propagation. In all the cases considered there are no magnetic flux surfaces. However, radial transport is observed to depend strongly on $\\epsilon$ due to the presence of high-order magnetic islands and Cantori that act as quasi-transport barriers that preclude the radial penetration of heat pulses within physically relevant time scale. The dependence of the magnetic field connection length, $\\ell_B$, on $\\epsilon$ is studied in detail. The decay rate of the temperature maximum...

  19. Critical electric field strengths of onion tissues treated by pulsed electric fields.

    Science.gov (United States)

    Asavasanti, Suvaluk; Ersus, Seda; Ristenpart, William; Stroeve, Pieter; Barrett, Diane M

    2010-09-01

    The impact of pulsed electric fields (PEF) on cellular integrity and texture of Ranchero and Sabroso onions (Allium cepa L.) was investigated. Electrical properties, ion leakage rate, texture, and amount of enzymatically formed pyruvate were measured before and after PEF treatment for a range of applied field strengths and number of pulses. Critical electric field strengths or thresholds (E(c)) necessary to initiate membrane rupture were different because dissimilar properties were measured. Measurement of electrical characteristics was the most sensitive method and was used to detect the early stage of plasma membrane breakdown, while pyruvate formation by the enzyme alliinase was used to identify tonoplast membrane breakdown. Our results for 100-μs pulses indicate that breakdown of the plasma membrane occurs above E(c)= 67 V/cm for 10 pulses, but breakdown of the tonoplast membrane is above either E(c)= 200 V/cm for 10 pulses or 133 V/cm for 100 pulses. This disparity in field strength suggests there may be 2 critical electrical field strengths: a lower field strength for plasma membrane breakdown and a higher field strength for tonoplast membrane breakdown. Both critical electric field strengths depended on the number of pulses applied. Application of a single pulse at an electric field up to 333 V/cm had no observable effect on any measured properties, while significant differences were observed for n≥10. The minimum electric field strength required to cause a measurable property change decreased with the number of pulses. The results also suggest that PEF treatment may be more efficient if a higher electric field strength is applied for a fewer pulses.

  20. 肠道沙门菌O:4(B)菌群脉冲场凝胶电泳分子分型%Molecular Typing of Salmonella Serotype O:4(B) by Using Pulsed-field Gel Electrophoresis

    Institute of Scientific and Technical Information of China (English)

    王红; 黄彦; 唐振柱; 孙贵娟; 李秀桂; 韦程媛

    2011-01-01

    为了明确2010年食源性疾病监测中分离的肠道沙门菌O:4(B)菌群的PFGE分子型别,探讨其多态性及其与分子流行病学关系,我们将分离获得的29株O:4(B)血清型沙门菌进一步鉴定培养,挑取单个菌落增菌,供试菌株基因组DNA用限制性内切酶xbaI消化酶切后进行脉冲场凝胶电泳分型,所得结果用Bionumerics5.1软件进行聚类分析。实验结果表明,根据电泳指纹图谱,可将29株肠道沙门菌O:4(B)菌群分为24个PFGE型别,菌株间的相似值在56.31%~100%之间,同一血清型别的沙门菌有多个PFGE型别。脉冲场凝胶电泳对O:4(B)群沙门菌有较高的分型能力,可有效的应用于食物中沙门菌溯源分析及分子流行病学研有。%The objective of the present study was to document the polymorphism of PFGE molecular type of Salmonella enterica subsp, enterica serotype O:4(B) which isolated from food-borne diseases and to explore theirs relationship of molecular epidemiological. In this research, 29 Salmonella stains were identified and the single colony was picked and enriched. Then the total genomic DNA of the isolates was digested with restriction enzyme Xba I, and run pulsed-field gel electrophoresis (PFGE). The DNA fingerprints of different stains were analyzed by Bionumerics5.1 software to perform clustering. The DNA fingerprints of 29 Salmonella were belonged to 24 PFGE pattern combinations. Similarity value of these strains was in the range of 56.31%-100%. One serotype Salmonella could be found several PFGE pattern combinations. The PFGE technology is a good method for molecular typing of Salmonella serotype O:4(B) and could be effectively apply on tracing the suspected source of food contamination and investigate the food-poisoning and also study the molecular epidemiological relationship of different Salmonella stains.

  1. Molecular epidemiological survey with pulsed-field gel electrophoresis on two simultaneous but allopatric food-poisoning accidents caused by Salmonella enteritidis%脉冲场电泳在两起同期异地肠炎沙门菌食物中毒分子流行病学调查中的应用研究

    Institute of Scientific and Technical Information of China (English)

    黄彦; 孙贵娟; 唐振柱; 李秀桂; 王红

    2011-01-01

    目的 探讨两起相距210多公里乡镇同期发生的肠炎沙门菌食物中毒分离株之间的分子流行病学关系.方法 将两起食物中毒事件患者和剩余食物分离到的8株肠炎沙门菌进一步鉴定培养,挑取单个菌落增菌,用限制性内切酶Xba I消化酶切后进行脉冲场凝胶电泳,获得的分子分型指纹图谱,运用Bionumerics 5.1进行聚类分析.结果 指纹图谱聚类显示8株肠炎沙门菌分为两个分子型,D乡食物中毒分离到的5株肠炎沙门菌有相同的指纹图谱;P镇的3株分离株图谱也一致;两起食物中毒分离株图谱之间有4个条带的差异.结论两起食物中毒的暴发虽然都是肠炎沙门菌引起的,但具有不同的分子型别,食物中毒不是由同一种污染的食物源引起;脉冲场凝胶电泳可有效应用于食物中毒溯源分析及肠炎沙门菌分子流行病学研究.%Objective To study the molecular epidemiology of two Salmonella enteritidis strains in two food-poisoning accidents occurred at the same time but separated in a distance of 210 kilometers away from each other. Methods Eight S. Enteritidis stains isolated from patients and food residues in two food-poisoning accidents were identified, and single colonies were picked out to multiply on agar plates. The total DNA of isolates was digested with restriction enzyme Xba I, and run pulsed-field gel electrophoresis ( PFCE). The DNA fingerprints of different stains were compared by using Bionumerics 5. 1. Results The DNA fingerprints of 8 S. Enteritidis belonged to two PFCE patterns. The fingerprints of 5 stains isolated from D town were consistent and also that of 3 stains from P town, but the PFCE patterns from different towns were varied in four bands. Conclusion This two food-poisoning accidents were caused by S. Enteritidis with different PFCE patterns, so they were not infected by the same contaminated food source. The PFCE technology can be effectively applied in tracing

  2. Genotypic variability and persistence of Legionella pulsed-field gel electrophoresis patterns in 16 cooling towers in Shanghai, China%上海市16个冷却塔水中军团菌脉冲场凝胶电泳分型及基因型监测

    Institute of Scientific and Technical Information of China (English)

    陈明亮; 王刚毅; 陈敏; 周海健; 邵祝军; 张曦; 吴凡

    2010-01-01

    目的 研究上海市公共场所16个空调冷却塔水中军团菌的脉冲场凝胶电泳(PFGE)分型,并连续监测该菌基因型变化.方法 2007年5-10月连续6个月以每月1次的频率采样,从16个公共场所空调冷却塔水中分离军团菌,经血清学凝集试验、胶乳凝集试验分型后,使用PFGE技术对酶切后的军团菌全染色体DNA进行电泳获得指纹图谱,利用BioNumerics软件进行聚类分析.结果 16个冷却塔水中共分离出131株军团菌,包括嗜肺军团菌、博杰曼军团菌、米克戴德军团菌和茴香军团菌,分为52个PFGE型别,其中37个PFGE型别(71.15%)仅分布于1个冷却塔中,即为该冷却塔所特有;15个PFGE型别(28.85%)分布于2个或以上冷却塔中.16个冷却塔具有2个或以上的PFGE型,13个冷却塔(81.25%)中多次出现相同的PFGE型别.2007年6-10月连续5个月从6个冷却塔中分离出18株PFGE型为LPAs.SH0078型的军团菌.结论 冷却塔水中的军团菌基因型具有多样性和复杂性,81.25%的冷却塔水中PFGE型具有持续性,且LPAs.SH0078型广泛分布,可能为优势PFGE型.%Objective To investigate the genotypic characteristics and persistence of Legionella pulsed-field gel electrophoresis (PFGE) patterns in 16 air-conditioner cooling towers in six different public sites of Shanghai. Methods From May to October, continuous sampling was operated once per month in 2007. Legionella strains isolated from the 16 cooling towers were confirmed by serological and latex agglutination. PFGE was applied for the fingerprinting of the isolates, while the culster results of PFGE were analyzed by BioNumerics software. Results 131 strains of Legionella were isolated, including L. pneumophila, L. bozemanae, L. micdadei and L anisa.52 distinguishable PFGE patterns were differentiated among the 16 cooling towers, with 37 patterns were owned by just one cooling tower, which was not shared with other cooling towers, while 15 patterns were shared by more

  3. Rapid identification of 40 strains of multidrug-resistant Acinetobacter baumannii clones by pulsed-field gel electrophoresis and investigation of their susceptibility to lytic bacteriophages%40株多重耐药鲍氏不动杆菌同源性和噬菌体裂解谱分析

    Institute of Scientific and Technical Information of China (English)

    牛文凯; 郭雷静; 苑鑫; 柏长青; 彭帆; 童贻刚

    2015-01-01

    Objective To determine the genetic diversity of multidrug-resistant Acinetobacter baumannii (MDRAB) strains and to test their susceptibility to bacteriophages.Methods Acinetobacter baumannii was isolated from hospitalized patients from January 2012 to December 2012.Bacterial resistance to antibiotic was tested by Kirb-Bauer method.Genotyped was detected by pulsed-field gel electrophoresis.Bacteriophages were isolated from raw sewage using these Acinetobacter baumannii strain as host cells,lysis spectrum was determined by phage plaque.Results 40 Acinetobacter baumannii were resistant to multiple antibiotics including carbapenems and β-lactamase inhibitors.The genotypes were distributed into three clones containing 4,26,and 4 isolates respectively.Other six isolates were singletons.16 strains of Acinetobacter bacteriophages with different lysis spectrum were isolated.The cocktail,which was made of three newly isolated Acinetobacter bacteriophages,was found to lyse 30 of the 40 analyzed strains and distributed into the different clonal complexes.Conclusions This pilot study suggests that systematic genotyping of MDRAB strains can improve our epidemiological understanding of transmission in the hospital.Phage can effectively destroy MDRAB and deserve further research.%目的 分析多重耐药鲍氏不动杆菌(MDRAB)同源性和噬菌体的裂解谱.方法 从解放军三○七医院2012年住院患者临床标本中分离MDRAB,K-B法检测细菌耐药性,脉冲场凝胶电泳(PFGE)分析其同源性,采用医院污水富集法分离噬菌体,平皿斑点法观察裂解谱.结果 40株MDRAB对18种常用抗生素呈现高度耐药,亚胺培南的耐药率达87.5%,对头孢哌酮/舒巴坦的耐药率为75.0%.PFGE分型显示40株MDRAB分A、B、C3个克隆型,其中A型4株,B型26株,C型4株,另有6株相对独立菌株.成功分离出16株MDRAB裂解性噬菌体,用来自不同克隆群的3种噬菌体制成鸡尾酒可裂解30株(75.0%)MDRAB.结论 PFGE分

  4. Two-photon Compton process in pulsed intense laser fields

    CERN Document Server

    Seipt, D

    2012-01-01

    Based on strong-field QED in the Furry picture we use the Dirac-Volkov propagator to derive a compact expression for the differential emission probability of the two-photon Compton process in a pulsed intense laser field. The relation of real and virtual intermediate states is discussed, and the natural regularization of the on-shell contributions due to the finite laser pulse is highlighted. The inclusive two-photon spectrum is two orders of magnitude stronger than expected from a perturbative estimate.

  5. Dielectric Fluid in Inhomogeneous Pulsed Electric Field

    CERN Document Server

    Shneider, M N

    2013-01-01

    We consider the dynamics of a compressible fluid under the influence of electrostrictive ponderomotive forces in strong inhomogeneous nonstationary electric fields. It is shown that if the fronts of the voltage rise at a sharp, needle-like electrode are rather steep (less than or about nanoseconds), and the region of negative pressure arises, which can reach values at which the fluid loses its continuity with the formation of cavitation ruptures. If the voltage on the electrode is not large enough or the front is flatter, the cavitation in the liquid does not occur. However, a sudden shutdown of the field results in a reverse flow of liquid from the electrode, which leads to appearance of negative pressure, and, possibly, cavitation.

  6. Nanosecond pulsed electric field ablation of hepatocellular carcinoma.

    Science.gov (United States)

    Beebe, Stephen J; Chen, Xinhua; Liu, Jie A; Schoenbach, Karl H

    2011-01-01

    Hepatocellular carcinoma often evades effective therapy and recurrences are frequent. Recently, nanosecond pulsed electric field (nsPEF) ablation using pulse power technology has emerged as a local-regional, non-thermal, and non-drug therapy for skin cancers. In the studies reported here we use nsPEFs to ablate murine, rat and human HCCs in vitro and an ectopic murine Hepa 1-6 HCC in vivo. Using pulses with 60 or 300 ns and electric fields as high as 60 kV/cm, murine Hepa 1-6, rat N1S1 and human HepG2 HCC are readily eliminated with changes in caspase-3 activity. Interestingly caspase activities increase in the mouse and human model and decrease in the rat model as electric field strengths are increased. In vivo, while sham treated control mice survived an average of 15 days after injection and before humane euthanasia, Hepa 1-6 tumors were eliminated for longer than 50 days with 3 treatments using one hundred pulses with 100 ns at 55 kV/cm. Survival was 40% in mice treated with 30 ns pulses at 55 kV/cm. This study demonstrates that nsPEF ablation is not limited to effectively treating skin cancers and provides a rationale for treating orthotopic hepatocellular carcinoma in pre-clinical applications and ultimately in clinical trials.

  7. Dosimetric Evaluation of Linac Photon Small Fields using MAGIC Polymer Gels

    Directory of Open Access Journals (Sweden)

    Hossein Hasani

    2011-09-01

    Full Text Available Introduction: In radiotherapy, methods of treatment planning are becoming increasingly more complicated. This requires verification of the doses delivered to increasingly smaller and more precise regions. Radiotherapy techniques are continuously employing smaller and smaller field sizes to deliver tighter radiation doses with higher therapeutic ratios, generating interest among researchers to provide reliable dosimetry for beams and treatment plans collimated to small field sizes. In this study, the dosimetry of these fields was evaluated in clinical applications by using polymer gel dosimetry. Material and Methods: The MAGIC polymer gel was used in this study. The gel samples were manufactured and poured into phantoms and calibration vials and were irradiated with a 6 MV x-ray beam. The R2 maps of the dose distributions were obtained from the gel MR images. The depth dose distributions and dose profile measurements were measured in different fields at a depth of 5 cm in gel, and were compared against another technique using a pinpoint chamber. Results: Comparison of the results of gel and pinpoint chamber measurements showed largest differences between the dose profile measurements in the low dose regions (near the edges. In these regions, the pinpoint-chamber measured penumbra width was at most 3.2 mm wider than those given by gel dosimeters. For a 30 × 30 mm2 field, maximum difference between gel and pinpoint chamber was 2 mm within the depth of maximum dose region, and were 2 mm, 3 mm and 2 mm for 20 × 20 mm2, 10 × 10 mm2 and 5 × 5 mm2 fields, respectively. The maximum differences within the buildup region for 30 × 30 mm2, 20 × 20 mm2, 10 × 10 mm2 and 5 × 5 mm2 fields were 9%, 4.5%, 2% and 9%, respectively. Discussion and Conclusion: The differences in the depth dose distributions and dose profile measurements between MAGIC polymer gel and pinpoint chamber are attributable to different factors. The dosimetry of these fields using

  8. Pulsed electric fields (PEF applications on wine production: A review

    Directory of Open Access Journals (Sweden)

    Ozturk Burcu

    2017-01-01

    Full Text Available Novel techniques have been searched in the last decades as a result of increasing demand for high quality food products. Non-thermal processing technologies, such as pulsed electric fields (PEF have been improved to achieve inhibition of deleterious effects on quality-related compounds. The working principle of PEF is based on the application of pulses of high voltage (typically above 20 kV/cm up to 70 kV/cm to liquid foods placed between two electrodes. Pulsed electric fields technique has also been studied in winemaking process. Certain positive influences of PEF on vinification have been reported as elimination of pathogenic microorganisms, reduction of maceration time, increase in phenolic compounds extraction , acceleration of wine aging and inactivation of oxidative enzymes. The aim of this review is to summarize the potential applications of PEF in winemaking and to express its effects on quality of wine.

  9. Transcranial pulsed electromagnetic fields for multiple chemical sensitivity

    DEFF Research Database (Denmark)

    Tran, Marie Thi Dao; Skovbjerg, Sine; Arendt-Nielsen, Lars

    2013-01-01

    . The symptoms may have severe impact on patients' lives, but an evidence-based treatment for the condition is nonexisting. The pathophysiology is unclarified, but several indicators point towards abnormal processing of sensory signals in the central nervous system. Pulsed electromagnetic fields (PEMF) offer...

  10. Pulsed electric field (PEF)research at USDA, ARS, ERRC

    Science.gov (United States)

    This article summarizes the effects of pulsed electric fields on the microbiological safety and quality aspects of various liquid food matrices, obtained at USDA, ARS, Eastern Regional Research Center under CRIS Project No. 1935-41420-013-00D, Processing Intervention Technologies for Enhancing the S...

  11. Pulsed electric field processing for fruit and vegetables

    Science.gov (United States)

    This month’s column reviews the theory and current applications of pulsed electric field (PEF) processing for fruits and vegetables to improve their safety and quality. This month’s column coauthor, Stefan Toepfl, is advanced research manager at the German Institute of Food Technologies and professo...

  12. Transcranial pulsed electromagnetic fields for multiple chemical sensitivity

    DEFF Research Database (Denmark)

    Tran, Marie Thi Dao; Skovbjerg, Sine; Arendt-Nielsen, Lars

    2013-01-01

    . The symptoms may have severe impact on patients' lives, but an evidence-based treatment for the condition is nonexisting. The pathophysiology is unclarified, but several indicators point towards abnormal processing of sensory signals in the central nervous system. Pulsed electromagnetic fields (PEMF) offer...

  13. Average Number of Coherent Modes for Pulse Random Fields

    CERN Document Server

    Lazaruk, A M; Lazaruk, Alexander M.; Karelin, Nikolay V.

    1997-01-01

    Some consequences of spatio-temporal symmetry for the deterministic decomposition of complex light fields into factorized components are considered. This enables to reveal interrelations between spatial and temporal coherence properties of wave. An estimation of average number of the decomposition terms is obtained in the case of statistical ensemble of light pulses.

  14. Efficacy in Microbial Sterilization of Pulsed Magnetic Field Treatment

    Science.gov (United States)

    Sterilization effects of the pulsed magnetic field with a maximum intensity of 11.37 Tesla were investigated on Escherichia coli AS 1.129, Staphylococcus aureus AS 1.89, Saccharomyces cerevisiae ATTC 7552 and Bacillus subtilis AS 1.921. The well-regulated fluctuations of sterilization effects with m...

  15. Trapped magnetic field measurements on HTS bulk by peak controlled pulsed field magnetization

    Energy Technology Data Exchange (ETDEWEB)

    Ida, Tetsuya; Watasaki, Masahiro [Department of Electronic Control Engineering, Hiroshima National College of Maritime Technology, 4272-1, Higashino, Ohsakikamijima-cho, Toyota-gun, Hiroshima 725-0231 (Japan); Kimura, Yosuke [Kawasaki Heavy Industries, Ltd. Technical Institute System Technology Development Centre 1-1, Kawasaki-cho, Akashi-shi, Hyogo 673-8666 (Japan); Miki, Motohiro; Izumi, Mitsuru, E-mail: ida@hiroshima-cmt.ac.j [Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, 2-1-6, Etchu-jima, Koto-ku, Tokyo 135-8533 (Japan)

    2010-06-01

    For the past several years, we have studied the high-temperature superconducting (HTS) synchronous motor assembled with melt-textured Gd-Ba-Cu-O bulk magnets. If the single pulse field magnetizes a bulk effectively, size of electrical motor will become small for the strong magnetic field of the HTS magnets without reducing output power of motor. In the previous study, we showed that the HTS bulk was magnetized to excellent cone-shape magnetic field distribution by using the waveform control pulse magnetization (WCPM) method. The WCPM technique made possible the active control of the waveform on which magnetic flux motion depended. We generated the pulse waveform with controlled risetime for HTS bulk magnetization to suppress the magnetic flux motion which decreases magnetization efficiency. The pulsed maximum magnetic flux density with slow risetime is not beyond the maximum magnetic flux density which is trapped by the static field magnetization. But, as for applying the pulse which has fast risetime, the magnetic flux which exceed greatly the threshold penetrates the bulk and causes the disorder of the trapped magnetic distribution. This fact suggests the possibility that the threshold at pulsed magnetization influences the dynamic magnetic flux motion. In this study, Gd-Ba-Cu-O bulk is magnetized by the controlled arbitrary trapezoidal shape pulse, of which the maximum magnetic flux density is controlled not to exceed the threshold. We will present the trapped magnetic characteristics and the technique to generate the controlled pulsed field.

  16. Pulse-front propagation and interaction during the growth of CdS nanoparticles in a gel.

    Science.gov (United States)

    Al-Ghoul, Mazen; Ghaddar, Tarek; Moukalled, Tharwat

    2009-08-27

    We studied the spatiotemporal dynamics of a new system consisting of sulfide ions (outer electrolyte) diffusing into an organic gel (gelatin) containing mercaptoethanol-capped cadmium ions (inner electrolyte). The product, cadmium sulfide, exhibits a faint yellow transparent propagating front starting at the gel-outer electrolyte interface. When subjected to UV light, this system reveals fluorescing CdS nuclei localized spatially in a narrow region, called pulse, that leads the front and propagates down the tube. We show that the pulse consists of CdS nanoclusters of an average size of about 4 nm, whereas the trailing front consists of 6-8 nm cubic-phase CdS crystallites. The width of the pulse remains constant in time, t, at about 2 mm and independent of the outer concentration S0. It was found that the speed of the pulse fluctuates as the concentration of the capping agent is varied, with fastest pulses attained at a concentration of 40 mM for two different outer concentrations of sulfide ions. The origin of the yellow fluorescence of the pulse originates from emission from surface states. This dynamical system was then theoretically studied using a competitive particle growth model. The resulting evolution equations were solved numerically, and the results were compared to the experimental findings. It was shown that the model agrees in many aspects with the experiment. The densities of small particles and large particles rho were shown to evolve like a pulse and a front, respectively. The front was shown to extend "diffusively" as t1/2, as found experimentally. The distance traveled by the pulse xpeak was shown to increase with outer concentration S0 and obeys a concentration power law xpeak approximately S(0)1/4. The width w of the pulse also obeys a time power law w approximately ta with a crossover between early times (a=1/3) and intermediate times (a=0). This system would enable us to study the early time dynamics of Liesegang systems.

  17. Review of the Dynamics of Coalescence and Demulsification by High-Voltage Pulsed Electric Fields

    OpenAIRE

    Ye Peng; Tao Liu; Haifeng Gong; Xianming Zhang

    2016-01-01

    The coalescence of droplets in oil can be implemented rapidly by high-voltage pulse electric field, which is an effective demulsification dehydration technological method. At present, it is widely believed that the main reason of pulse electric field promoting droplets coalescence is the dipole coalescence and oscillation coalescence in pulse electric field, and the optimal coalescence pulse electric field parameters exist. Around the above content, the dynamics of high-voltage pulse electric...

  18. Wave packet dynamics under effect of a pulsed electric field

    Science.gov (United States)

    da Silva, A. R. C. B.; de Moura, F. A. B. F.; Dias, W. S.

    2016-06-01

    We studied the dynamics of an electron in a crystalline one-dimensional model under effect of a time-dependent Gaussian field. The time evolution of an initially Gaussian wave packet it was obtained through the numerical solution of the time-dependent Schrödinger equation. Our analysis consists of computing the electronic centroid as well as the mean square displacement. We observe that the electrical pulse is able to promote a special kind of displacement along the chain. We demonstrated a direct relation between the group velocity of the wave packet and the applied electrical pulses. We compare those numerical calculations with a semi-classical approach.

  19. Rheological properties and formation mechanism of DC electric fields induced konjac glucomannan-tungsten gels.

    Science.gov (United States)

    Wang, Lixia; Jiang, Yaoping; Lin, Youhui; Pang, Jie; Liu, Xiang Yang

    2016-05-20

    Konjac glucomannan-tungsten (KGM-T) hydrogel of electrochemical reversibility was successfully produced under DC electric fields in the presence of sodium tungstate. The structure and the effects of sodium tungstate concentration, KGM concentration, voltage and electric processing time on the rheological properties of the gels were investigated. pH experiments showed that KGM sol containing Na2WO4·2H2O in the vicinity of the positive electrode became acidic and the negative electrode basic after the application of DC electric fields. Under acid conditions, WO4(2-) ions transformed into isopoly-tungstic acid ions. FTIR and Raman studies indicated that isopoly-tungstic acid ions absorbed on KGM molecular chain and cross-linked with -OH groups at C-6 position on sugar units of KGM. Frequency sweep data showed with increasing sodium tungstate concentration, voltage, and electric processing time, the viscoelastic moduli, i.e., the storage and the loss moduli of the gel increased, whereas an increase in KGM concentration led to a decrease in gel viscoelastic moduli. The temperature sweep measurements indicated the obtained gel exhibited high thermal stability. Finally, the mechanism of gel formation was proposed. Our work may pave the way to use DC electric fields for the design and development of KGM gels as well as polysaccharide gels.

  20. Miniature coils for producing pulsed inplane magnetic fields for nanospintronics

    Energy Technology Data Exchange (ETDEWEB)

    Pawliszak, Łukasz; Zgirski, Maciej [Institute of Physics, Polish Academy of Sciences, al.Lotnikow 32/46, PL 02-668 Warszawa (Poland); Tekielak, Maria [Faculty of Physics, University of Białystok, ul.Lipowa 41, PL 15-424 Białystok (Poland)

    2015-03-15

    Nanospintronic and related research often requires the application of quickly rising magnetic field pulses in the plane of the studied planar structure. We have designed and fabricated sub-millimeter-sized coils capable of delivering pulses of the magnetic field up to ∼500 Oe in the plane of the sample with the rise time of the order of 10 ns. The placement of the sample above the coil allows for easy access to its surface with manipulators or light beams for, e.g., Kerr microscopy. We use the fabricated coil to drive magnetic domain walls in 1 μm wide permalloy wires and measure magnetic domain wall velocity as a function of the applied magnetic field.

  1. Effective field theory for coherent optical pulse propagation

    CERN Document Server

    Park, Q H; Park, Q Han

    1996-01-01

    Hidden nonabelian symmetries in nonlinear interactions of radiation with matter are clarified. In terms of a nonabelian potential variable, we construct an effective field theory of self-induced transparency, a phenomenon of lossless coherent pulse propagation, in association with Hermitian symmetric spaces G/H. Various new properties of self-induced transparency, e.g. soliton numbers, effective potential energy, gauge symmetry and discrete symmetries, modified pulse area, conserved U(1)-charge etc. are addressed and elaborated in the nondegenerate two-level case where G/H = SU(2)/U(1). Using the U(1)-charge conservation, a new type of analysis on pulse stability is given which agrees with earlier numerical results.

  2. Maximum trapped field of a ring bulk superconductor by low pulsed field magnetization

    Energy Technology Data Exchange (ETDEWEB)

    Tsuchimoto, M. [Hokkaido Institute of Technology, 7-15 Maeda, Teine-ku, Sapporo 006-8585 (Japan)], E-mail: tsuchi@hit.ac.jp; Kamijo, H. [Railway Technical Research Institute, 2-8-38, Hikari-cho, Kokubunji, Tokyo 185-8540 (Japan)

    2007-10-01

    Pulsed field magnetization is an important technique for a bulk superconducting magnet, which is one practical application of a bulk high T{sub c} superconductor (HTS). Full magnetization of a ring HTS is effective to obtain large trapped field for low pulsed field magnetization. In this study, trapped field in a ring bulk superconductor by the low pulsed field magnetization is numerically analyzed under assumption of variable shielding current by the temperature control. Differences between one-dimensional Bean model and axisymmetric three-dimensional numerical solution are discussed through the analysis. There is maximum trapped field in the axisymmetric three-dimensional model because of finite thickness of the ring HTS. The shielding current density and inner radius of the ring HTS are discussed to obtain the maximum trapped field.

  3. Effect of pulsed electromagnetic fields on orthodontic tooth movement.

    Science.gov (United States)

    Stark, T M; Sinclair, P M

    1987-02-01

    The purpose of this study was to determine whether the application of a simple surgically noninvasive, pulsed electromagnetic field could increase both the rate and amount of orthodontic tooth movement observed in guinea pigs. In addition, the objective was to evaluate the electromagnetic field's effects on bony physiology and metabolism and to search for possible systemic side effects. Laterally directed orthodontic force was applied to the maxillary central incisors of a sample of 40 young male, Hartley guinea pigs (20 experimental, 20 control) by means of a standardized intraoral coil spring inserted under constricting pressure into holes drilled in the guinea pigs' two maxillary central incisors. During the experimental period, the guinea pigs were placed in specially constructed, plastic animal holders with their heads positioned in an area of uniform electromagnetic field. Control animals were placed in similar plastic holders that did not carry the electrical apparatus. The application of a pulsed electromagnetic field to the experimental animals significantly increased both the rate and final amount of orthodontic tooth movement observed over the 10-day experimental period. The experimental animals also demonstrated histologic evidence of significantly greater amounts of bone and matrix deposited in the area of tension between the orthodontically moved maxillary incisors. This increase in cellular activity was also reflected by the presence of significantly greater numbers of osteoclasts in the alveolar bone surrounding the maxillary incisors of the experimental animals. After a 10-day exposure to pulsed electromagnetic field, minor changes in serologic parameters relating to protein metabolism and muscle activity were noted. The results of this study suggest that it is possible to increase the rate of orthodontic tooth movement and bone deposition through the application of a noninvasive, pulsed electromagnetic field.

  4. Pulsed beams as field probes for precision measurement

    OpenAIRE

    Hudson, J. J.; Ashworth, H. T.; Kara, D. M.; Tarbutt, M. R.; Sauer, B.E.; Hinds, E. A.

    2007-01-01

    We describe a technique for mapping the spatial variation of static electric, static magnetic, and rf magnetic fields using a pulsed atomic or molecular beam. The method is demonstrated using a beam designed to measure the electric dipole moment of the electron. We present maps of the interaction region, showing sensitivity to (i) electric field variation of 1.5 V/cm at 3.3 kV/cm with a spatial resolution of 15 mm; (ii) magnetic field variation of 5 nT with 25 mm resolution; (iii) radio-frequ...

  5. LUPIN, a new instrument for pulsed neutron fields

    Science.gov (United States)

    Caresana, M.; Ferrarini, M.; Manessi, G. P.; Silari, M.; Varoli, V.

    2013-06-01

    A number of studies focused in the last decades on the development of survey meters to be used in pulsed radiation fields. This is a topic attracting widespread interest for applications such as radiation protection and beam diagnostics in accelerators. This paper describes a new instrument specifically conceived for applications in pulsed neutron fields (PNF). The detector, called LUPIN, is a rem counter type instrument consisting of a 3He proportional counter placed inside a spherical moderator. It works in current mode with a front-end electronics consisting of a current-voltage logarithmic amplifier, whose output signal is acquired with an ADC and processed on a PC. This alternative signal processing allows the instrument to be used in PNF without being affected by saturation effects. Moreover, it has a measurement capability ranging over many orders of burst intensity. Despite the fact that it works in current mode, it can measure a single neutron interaction. The LUPIN was first calibrated in CERN's calibration laboratory with a PuBe source. Measurements were carried out under various experimental conditions at the Helmholtz-Zentrum in Berlin, in the stray field at various locations of the CERN Proton Synchrotron complex and around a radiotherapy linear accelerator at the S. Raffaele hospital in Milan. The detector can withstand single bursts with values of H*(10) up to 16 nSv/burst without showing any saturation effect. It efficiently works in pulsed stray fields, where a conventional rem-counter underestimates by a factor of 2. It is also able to reject the very intense and pulsed photon contribution that often accompanies the neutron field with good reliability.

  6. 乳酸杆菌及嗜热链球菌脉冲场凝胶电泳分子分型方法建立及应用%Development of pulsed field gel electrophoresis and application for characterization and identification of Lactobacillus and Streptococcus thermophilus

    Institute of Scientific and Technical Information of China (English)

    董银苹; 崔生辉; 于红霞; 李凤琴

    2011-01-01

    目的 建立乳酸杆菌及嗜热链球菌的PFGE分子分型方法,并对北京市售酸奶中分离的乳酸杆菌及嗜热链球菌进行分子分型.方法 选取ApaⅠ、NotⅠ、sfiⅠ、XbaⅠ和SmaⅠ共5种PFGE分析中常用的限制性内切酶,对从北京市售酸奶中分离到的52株乳酸杆菌、嗜热链球菌以及相应的标准菌株进行酶切,优化PFGE限制性内切酶种类及电泳条件,并用优化出的实验条件对菌株进行分子分型,同时进行聚类分析,与生化鉴定及16s rRNA基因鉴定结果进行对比分析.结果 限制性内切酶NotⅠ对保加利亚乳酸杆菌、发酵乳酸杆菌和德氏乳酸杆菌的酶切效果较好,而限制性内切酶Apa Ⅰ对嗜热链球菌、嗜酸乳酸杆菌及干酪乳酸杆菌的酶切效果较好.24株保加利亚乳酸杆菌被分为8个PFGE型,15株嗜热链球菌被分为8个PFGE型,7株嗜酸乳酸杆菌被分为3个PFGE型,2株德氏乳酸杆菌分属于2个不同的PFGE型.结论 建立的PFGE方法分析结果与生化鉴定及16s rRNA基因鉴定结果高度符合,所建方法适用于乳酸杆菌及嗜热链球菌的分子分型.%Objective To develop a pulsed field gel electrophoresis (PFGE) method for molecular typing of Lactobacillus and Streptococcus thermophilus (S.thermophilus) and to apply it in identification and characterization of both bacteria isolated from yoghourt collected from Beijing supermarket.Methods The five most useful restriction enzymes includingApa Ⅰ,Not ],Sfi Ⅰ,Xba Ⅰ and Sma Ⅰ were chosen to cut DNA of 52 strains of Lactobacillus,S.thermophilus as well as associated standard bacteria strains.The endonucleases and electrophoresis conditions for PFGE analysis were optimized and applied in molecular typing of Lactobacillus and S.thermophilus isolates.Cluster analysis based on the PFGE data was conducted.The identification results of PFGE were compared with those obtained in biochemical and 16s ribosomal RNA PCR identification tests

  7. Study on the serotype、virulence genes and pulsed field gel electrophoresis molecular typing of Vibrio Parahaemolyticus isolated from clinical patients%副溶血性弧菌临床分离株血清型、毒力基因和PFGE分子分型特征分析

    Institute of Scientific and Technical Information of China (English)

    张勇; 赖植发; 周海涛; 李波; 陈润莉; 曾华书; 侯红斌

    2013-01-01

    Objective To investigate the serotype、virulence genes and molecular typing characteristics of Vibrio Parahaemolyticus isolated from diarrhea samples among 2007-2012.Methods The serotype was detected by using serological agglutination test.Thermo-stable direct hemolysin (tdh) and tdh-related hemolysin (trh) were detected by using real time PCR methods.56 strains 03:K6 were analyzed for molecular typing by pulsed field gel electrophoresis(PFGE).Results (1) There are 14 serotypes,including O3:K6 (114,67.9%)、O4:K8 (25,14.9%)、O3:K29 (6,3.6%) and et al.Compared with the serotypes of strains from food poison,these from sporadic cases with diarrhea were different,but the main serotype was also O3:K6.(2) There are 4 types of virulence genes,including tdh+ trh-(161,95.8%) 、tdh+ trh+ (3,1.8%) 、tdh-trh+ (1,0.6%)、tdh-trh-(3,1.8%).Compared with the virulence genes of strains from food poison,these from sporadic cases with diarrhea were different,but the main virulence gene was also tdh + trh-.3、56 strains belonged to 15 PFGE strips and the similar degree is higher than 86%.10 patterns (P1 ~ P4、P6、P7、P9、P1O、P12、P15) had at lest two strains.Conclusion The most V.Parahaemolyticus isolated from clinical patients was O3:K6 and tdh + trh-.PFGE strips of V.Parahaemolyticus of O3:K6 from clinical patients exhibited a high degree of similarity,and correlation was found among strains.%目的 分析从2007-2012年腹泻病例标本中分离的168株副溶血性弧菌血清型分布、毒力基因携带情况和PFGE分子分型特征.方法 采用血清学凝集实验,检测菌株的血清型别;采用实时荧光PCR方法,检测耐热性溶血毒素基因(tdh)和耐热性溶血毒素相关溶血毒素基因(trh);采用脉冲场凝胶电泳技术(PFGE),分析56株O3:K6型副溶血性孤菌的基因分型特征.结果 (1)168株菌可分为14种血清型,主要血清型为O3:K6(114,67.9%)、O4:K8(25,14.9%)、O3:K29(6,3.6%);食物中毒

  8. The effect of pulsed HIFU on the porosity and permeability of collagen gels: An in vitro study

    Science.gov (United States)

    Vipulanandan, Geethanjali; O'Neill, Brian E.

    2012-10-01

    Pulsed HIFU is hypothesized to alter permeability of the extracellular matrix by altering the collagen network. In this study, the ability of HIFU to disrupt the extracellular matrix, particularly Type I collagen, in vitro, was investigated in order to enhance the drug delivery to highly collagenous tumors. This was tested in vitro in two ways, first using dye penetration, and second, by confocal reflection microscopy. Based on the analyses, it was concluded that there was at least a three-fold increase in porosity of the collagen gels after HIFU treatment.

  9. Effects of pulsed electrical field processing on microbial survival, quality change and nutritional characteristics of blueberries

    Science.gov (United States)

    Whole fresh blueberries were treated using a parallel pulsed electric field (PEF) treatment chamber and a sanitizer solution (60 ppm peracetic acid [PAA]) as PEF treatment medium with square wave bipolar pulses at 2 kV/cm electric field strength, 1us pulse width, and 100 pulses per second for 2, 4, ...

  10. Long-pulse magnetic field facility at Zaragoza

    Science.gov (United States)

    Algarabel, P. A.; del Moral, A.; Martín, C.; Serrate, D.; Tokarz, W.

    2006-11-01

    The long-pulse magnetic field facility of the Laboratorio de Magnetismo - Instituto de Ciencia de Materiales de Aragón (Universidad de Zaragoza-CSIC) produces magnetic fields up to 31, with a pulse duration of 2.2s. Experimental set-ups for measurements of magnetization, magnetostriction and magnetoresistance are available. The temperature can be controlled between 1.4 and 335 K, being the inner bore of the He cryostat of 22.5 mm. Magnetization is measured using the mutual induction technique, the magnetostriction is determined with the strain-gage and the capacitive cantilever methods, and the magnetoresistance is measured by means of the aclock-in technique in the 4-probes geometry. An overview of the facility will be presented and the presently available experimental techniques will be discussed.

  11. Detachment of Conductive Coatings by Pulsed Electromagnetic Field

    OpenAIRE

    Mironov, V.; Tatarinov, A.; Kolbe, M; Gluschenkov, V.

    2016-01-01

    The paper presents results of studies on the detachment of conductive coatings from the metal substrate by pulsed electromagnetic field (PEMF). It is known that at the boundary of a metal substrate and an electrically conductive coating having different electrical conductivities sharp changes of PEMF strength arise. This effect has been used to remove a copper layer from a steel substrate. Experimental studies were carried out in the Riga Technical University (Latvia), West Sax...

  12. Pulsed field magnetization in rare-earth kagome systems

    Science.gov (United States)

    Hoch, M. J. R.; Zhou, H. D.; Mun, E.; Harrison, N.

    2016-02-01

    The rare-earth kagome systems R 3Ga5SiO14 (R  =  Nd or Pr) exhibit cooperative paramagnetism at low temperatures. Evidence for correlated spin clusters in these weakly frustrated systems has previously been obtained from neutron scattering and from ESR and NMR results. The present pulsed field (0-60 T, 25 ms) magnetization measurements made on single crystals of Nd3Ga5SiO14 (NGS) and Pr3Ga5SiO14 (PGS) at temperatures down to 450 mK have revealed striking differences in the magnetic responses of the two materials. For NGS the magnetization shows a low field plateau, saturation in high transient fields, and significant hysteresis while the PGS magnetization does not saturate in transient fields up to 60 T and shows no hysteresis or plateaus. Nd3+ is a Kramers ion while Pr3+ is a non-Kramers ion and the crystal field effects are quite different in the two systems. For the conditions used in the experiments the magnetization behavior is not in agreement with Heisenberg model predictions for kagome systems in which easy-axis anisotropy is much larger than the exchange coupling. The extremely slow spin dynamics found below 4 K in NGS is, however, consistent with the model for Kramers ions and provides a basis for explaining the pulsed field magnetization features.

  13. Pulsed field magnetization in rare-earth kagome systems.

    Science.gov (United States)

    Hoch, M J R; Zhou, H D; Mun, E; Harrison, N

    2016-02-03

    The rare-earth kagome systems R 3Ga5SiO14 (R  =  Nd or Pr) exhibit cooperative paramagnetism at low temperatures. Evidence for correlated spin clusters in these weakly frustrated systems has previously been obtained from neutron scattering and from ESR and NMR results. The present pulsed field (0-60 T, 25 ms) magnetization measurements made on single crystals of Nd3Ga5SiO14 (NGS) and Pr3Ga5SiO14 (PGS) at temperatures down to 450 mK have revealed striking differences in the magnetic responses of the two materials. For NGS the magnetization shows a low field plateau, saturation in high transient fields, and significant hysteresis while the PGS magnetization does not saturate in transient fields up to 60 T and shows no hysteresis or plateaus. Nd(3+) is a Kramers ion while Pr(3+) is a non-Kramers ion and the crystal field effects are quite different in the two systems. For the conditions used in the experiments the magnetization behavior is not in agreement with Heisenberg model predictions for kagome systems in which easy-axis anisotropy is much larger than the exchange coupling. The extremely slow spin dynamics found below 4 K in NGS is, however, consistent with the model for Kramers ions and provides a basis for explaining the pulsed field magnetization features.

  14. Trapped field measurements of Gd-Ba-Cu-O bulk superconductor in controlled pulse field magnetizing

    Energy Technology Data Exchange (ETDEWEB)

    Ida, T [Department of Electronic Control Engineering, Hiroshima National College of Maritime Technology, 4272-1, Higashino, Ohsakikamijima-cho, Toyota-gun, Hiroshima 725-0231 (Japan); Kimura, Y; Sano, T; Yamaguchi, K; Izumi, M [Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, 2-1-6, Etchu-jima, Koto-ku, Tokyo 135-8533 (Japan); Miki, M [Kitano Seiki Co. Ltd., 7-13-7, Chuo, Ohta-ku, Tokyo 143-0024 (Japan)], E-mail: ida@hiroshima-cmt.ac.jp

    2008-02-01

    For large-scale electric power application of the melt-processed high temperature superconductor (HTS) bulks, especially at rotating machine, development of trapping much higher magnetic fields by using pulsed magnetization technique is essential. It is difficult to use static field cooling (FCM) technique that is most effective magnetizing method for the general industrial HTS applications, because the FCM requires large-scale superconducting magnets. Because the rise in temperature due to the magnetic flux motion decreases the pinning force, we controlled the magnetic flux penetrating to the bulk for the effective magnetization. A couple of vortex-type copper coils applied a magnetic field to a Gd-Ba-Cu-O bulk, which dimension was 45mm in diameter and 19 mm in thickness. HTS bulk was magnetized by the controlled pulse field without passive LCR pulse. We controlled waveform by using the discharge current that IGBT chopper in pulse magnetizer intermitted. We applied the pulse magnetic field with the various risetime to the HTS bulk in liquid nitrogen. The various conditions of the controlled waveform pulse to trap well-dressed profile magnetized the Gd-Ba-Cu-O bulk, strongly at 77K. In the present study, we show several properties which was measured in the PFM of the HTS bulk.

  15. Clinical update of pulsed electromagnetic fields on osteoporosis

    Institute of Scientific and Technical Information of China (English)

    HUANG Li-qun; HE Hong-chen; HE Cheng-qi; CHEN Jian; YANG Lin

    2008-01-01

    Objective To understand the effects of low-frequency pulsed electromagnetic fields (PEMFs) on chronic bony pain,bone mineral density (BMD), bone strength and biochemical markers of bone metabolism in the patients of osteoporosis.Data sources Using the key words "pulsed electromagnetic fields" and "osteoporosis", we searched the PubMed for related studies published in English from January 1996 to December 2007. We also searched the China National Knowledge Infrastructure (CNKI) for studies published in Chinese from January 1996 to December 2007.Study selection Inclusion criteria: (1) all articles which referred to the effects of low-frequency pulsed magnetic fields on osteoporosis either in primary osteoporosis or secondary osteoporosis; (2) either observational studies or randomized controlled studies. Exclusion criteria: (1) articles on experimental studies about osteoporosis; (2) repetitive studies; (3)case reports; (4) meta analysis.Results Totally 111 related articles were collected, 101 of them were published in Chinese, 10 were in English.Thirty-four were included and the remaining 84 were excluded.Conclusions Low-frequency PEMFs relieves the pain of primary osteoporosis quickly and efficiently, enhances bone formation and increases BMD of secondary osteoporosis. But the effects of PEMFs on bone mineral density of primary osteoporosis and bone resorption were controversial.

  16. Effects of Pulsed Electromagnetic Fields on Osteoporosis Model

    Science.gov (United States)

    Xiaowei, Yang; Liming, Wang; Guan, Z. C.; Yaou, Zhang; Xiangpeng, Wang

    The purpose of this paper was to investigate the preventive effects and long term effects of extremely low frequency pulsed electromagnetic fields (PEMFs), generated by circular coils and pulsed electromagnetic fields stimulators, on osteoporosis in bilaterally ovariectomized rats. In preventive experiment, thirty three-month old female Sprague-Dawley rats were randomly divided into three different groups: sham (SHAM), ovariectomy (OVX), PEMFs stimulation (PEMFs). All rats were subjected to bilaterally ovariectomy except those in SHAM group. The PEMFs group was exposed to pulsed electromagnetic fields with frequency 15 Hz, peak magnetic induction density 2.2mT and exposure time 2 hours per day. The bone mineral density (BMD) of vertebra and left femur were measured by dual energy X-ray absorptiometry at eighth week, twelfth week and sixteenth week after surgery. In long term effects experiment, forty four rats were randomly divided into sham (14 rats, SHAM), ovariectomy group (10 rats, OVX), 15Hz PEMFs group(10 rats, 15Hz) and 30Hz PEMFs group(10 rats, 30Hz) at twenty-sixth week after surgery. Rats in PEMFs groups were stimulated sixteen weeks. In preventive experiment, the Corrected BMD of vertebra and femur was significantly higher than that of OVX group after 16 weeks (Ptreatment of osteoporosis.

  17. Electrochemotherapy by pulsed electromagnetic field treatment (PEMF in mouse melanoma B16F10 in vivo

    Directory of Open Access Journals (Sweden)

    Kranjc Simona

    2016-03-01

    Full Text Available Pulsed electromagnetic field (PEMF induces pulsed electric field, which presumably increases membrane permeabilization of the exposed cells, similar to the conventional electroporation. Thus, contactless PEMF could represent a promising approach for drug delivery.

  18. Forming Reversible Gels with Triblock Polyelectrolytes: a Field-theoretic Study

    Science.gov (United States)

    Audus, Debra; Fredrickson, Glenn

    2011-03-01

    Recently, two research groups have formed reversible gels using triblock polyelectrolytes (Lemmers et al. 2010; Hunt et al., in preparation). This gel formation is driven by a phenomenon called complex coacervation, in which two oppositely charged homopolymers in solution phase separate into a polymer rich phase, known as a coacervate, and a solution phase. If instead, the polymers are triblocks with a neutral midblock and charged end blocks, under appropriate conditions they will microphase separate into micelles with cores of coacervated charged groups and coronas of neutral midblocks. These neutral midblocks act as bridges between the micelles, thereby creating a gel. One of the advantages of forming gels in this way is that the coacervate domains, and thus the gel, can be easily tuned by varying parameters such as pH, salt concentration and temperature. In order to understand the microstructures and solution sensitivity of these reversible gels, we have numerically simulated field-theoretic models of triblock polyelectrolyte mixtures in an implicit solvent. Because coacervation is driven by charge correlations, the usual mean-field assumption fails, and it is necessary to study the model beyond the level of SCFT.

  19. Effects of an external magnetic field in pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, T. [Universidad Autonoma de la Ciudad de Mexico (UACM), Prolongacion San Isidro 151, Col. San Lorenzo Tezonco, C.P. 09790, Mexico DF (Mexico)], E-mail: tupacgarcia@yahoo.com; Posada, E. de [CINVESTAV-IPN Unidad Merida, Applied Physics Department, A.P. 73, Cordemex, C.P. 97130 Merida, Yuc. (Mexico); Villagran, M. [CCADET, Universidad Nacional Autonoma de Mexico (UNAM), A.P. 70-186, C.P. 04510, Mexico DF (Mexico); Ll, J.L. Sanchez [Laboratorio de Magnetismo, Facultad de Fisica-IMRE, Universidad de La Habana, La Habana 10400 (Cuba); Bartolo-Perez, P.; Pena, J.L. [CINVESTAV-IPN Unidad Merida, Applied Physics Department, A.P. 73, Cordemex, C.P. 97130 Merida, Yuc. (Mexico)

    2008-12-30

    Thin films were grown by pulsed laser deposition, PLD, on Si (1 0 0) substrates by the ablation of a sintered ceramic SrFe{sub 12}O{sub 19} target with and without the presence of a nonhomogeneous magnetic field of {mu}{sub 0}H = 0.4 T perpendicular to substrate plane and parallel to the plasma expansion axis. The field was produced by a rectangular-shaped Nd-Fe-B permanent magnet and the substrate was just placed on the magnet surface (Aurora method). An appreciable increment of optical emission due to the presence of the magnetic field was observed, but no film composition change or thickness increment was obtained. It suggests that the increment of the optical emission is due mainly to the electron confinement rather than confinement of ionic species.

  20. Generation and measurement of pulsed high magnetic field

    CERN Document Server

    Jana, S

    2000-01-01

    Pulsed magnetic field has been generated by discharging a capacitor bank through a 5-layer air-core solenoid. The strength of the magnetic field at its peak has been measured using the voltage induced in various pick-up coils, and also from the Zeeman splitting of an ion having a known g value. Synchronizing a xenon flash at the peak of the magnetic field, this lab-made instrument has been made well suited to study the Zeeman effect, etc. at a temperature of 25 K. As an application of this setup, we have investigated the Zeeman splitting of the sup 4 I sub 9 sub / sub 2-> sup 4 G sub 5 sub / sub 2 transition of the Nd sup 3 sup + -doped CsCdCl sub 3 crystal at 7.8 T, and determined the splitting factors.

  1. Relaxation Dynamics of Ferroelectric Liquid Crystals in Pulsed Electric Field

    Science.gov (United States)

    Kudreyko, A. A.; Migranov, N. G.; Migranova, D. N.

    2016-11-01

    In this contribution we report a theoretical study of relaxation processes in surface-stabilized ferroelectric liquid crystals with spontaneous polarization. The influence of pulsed electric field on the behavior of ferroelectric liquid crystal in the SmC* phase, which is placed in a thin cell with strong anchoring of SmC* molecules with the boundary substrate, is studied. In the vicinity of the substrate interface, temporal dependence of the azimuthal motion of the director induced by electric field is obtained. The response to the external distortion of ferroelectric liquid crystal confined between two microstructured substrates is the occurrence of periodic temporal formation of solitons connected with the distortion of the director field n in the sample bulk. The interplay between microstructured substrates and director distribution of the ferroelectric SmC* phase is explained by the Frenkel-Kontorova model for a chain of atoms, but adapted for the continuum problem.

  2. Pulsed neutron fields measurements around a synchrotron storage ring

    Science.gov (United States)

    Caresana, Marco; Ballerini, Marcello; Ulfbeck, David Garf; Hertel, Niels; Manessi, Giacomo Paolo; Søgaard, Carsten

    2017-09-01

    A measurement campaign was performed for characterizing the neutron ambient dose equivalent, H*(10), in selected positions at ISA, Aarhus, Denmark, around the ASTRID and ASTRID2 storage rings. The neutron stray radiation field is characterized here by very intense radiation bursts with a low repetition rate, which result in a comparatively low average H*(10) rate. As a consequence, devices specifically conceived for operating in pulsed neutron fields must be employed for efficiently measuring in this radiation environment, in order to avoid severe underestimations of the H*(10) rate. The measurements were performed with the ELSE NUCLEAR LUPIN 5401 BF3-NP rem counter, a detector characterized by an innovative working principle that is not affected by dead time losses. This allowed characterizing both the H*(10) and the time structure of the radiation field in the pre-selected positions.

  3. Comparison of pulsed corona plasma and pulsed electric fields for the decontamination of water containing Legionella pneumophila as model organism.

    Science.gov (United States)

    Banaschik, Robert; Burchhardt, Gerhard; Zocher, Katja; Hammerschmidt, Sven; Kolb, Juergen F; Weltmann, Klaus-Dieter

    2016-12-01

    Pulsed corona plasma and pulsed electric fields were assessed for their capacity to kill Legionella pneumophila in water. Electrical parameters such as in particular dissipated energy were equal for both treatments. This was accomplished by changing the polarity of the applied high voltage pulses in a coaxial electrode geometry resulting in the generation of corona plasma or an electric field. For corona plasma, generated by high voltage pulses with peak voltages of +80kV, Legionella were completely killed, corresponding to a log-reduction of 5.4 (CFU/ml) after a treatment time of 12.5min. For the application of pulsed electric fields from peak voltages of -80kV a survival of log 2.54 (CFU/ml) was still detectable after this treatment time. Scanning electron microscopy images of L. pneumophila showed rupture of cells after plasma treatment. In contrast, the morphology of bacteria seems to be intact after application of pulsed electric fields. The more efficient killing for the same energy input observed for pulsed corona plasma is likely due to induced chemical processes and the generation of reactive species as indicated by the evolution of hydrogen peroxide. This suggests that the higher efficacy and efficiency of pulsed corona plasma is primarily associated with the combined effect of the applied electric fields and the promoted reaction chemistry.

  4. Analysis of circular wave packets generated by pulsed electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, S., E-mail: shuhei@concord.itp.tuwien.ac.at [Institute for Theoretical Physics, Vienna University of Technology, Vienna (Austria); Reinhold, C.O. [Physics Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831-6372 (United States); Department of Physics, University of Tennessee, Knoxville, TN 37996 (United States); Burgdoerfer, J. [Institute for Theoretical Physics, Vienna University of Technology, Vienna (Austria); Department of Physics, University of Tennessee, Knoxville, TN 37996 (United States); Wyker, B.; Ye, S.; Dunning, F.B. [Department of Physics and Astronomy and the Rice Quantum Institute, Rice University, Houston, TX 77005-1892 (United States)

    2012-05-15

    We demonstrate that circular wave packets in high Rydberg states generated by a pulsed electric field applied to extreme Stark states are characterized by a position-dependent energy gradient that leads to a correlation between the principal quantum number n and the spatial coordinate. This correlation is rather insensitive to the initial state and can be seen even in an incoherent mix of states such as is generated experimentally allowing information to be placed into, and extracted from, such wave packets. We show that detailed information on the spatial distribution of a circular wave packet can be extracted by analyzing the complex phase of its expansion coefficients.

  5. Analysis of Circular Wave Packets Generated by Pulsed Electric Fields

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, S. [Vienna University of Technology, Austria; Reinhold, Carlos O [ORNL; Burgdorfer, J. [Vienna University of Technology, Austria; Wyker, B. [Rice University; Ye, S. [Rice University; Dunning, F. B. [Rice University

    2011-01-01

    We demonstrate that circular wave packets in high Rydberg states generated using a pulsed electric field applied to extreme Stark states are characterized by a position-dependent energy gradient that leads to a correlation between the principal quantum number n and the spatial coordinate. This correlation is rather insensitive to the initial state and can be seen even in an incoherent mix of states such as is generated experimentally allowing information to be placed into, and extracted from, such wavepackets. We show that detailed information on the spatial distribution of a circular wave packet can be extracted by analyzing the complex phase of its expansion coefficient.

  6. Effects of shape and size of agar gels on heating uniformity during pulsed microwave treatment.

    Science.gov (United States)

    Soto-Reyes, Nohemí; Temis-Pérez, Ana L; López-Malo, Aurelio; Rojas-Laguna, Roberto; Sosa-Morales, María Elena

    2015-05-01

    Model gel systems with different shape (sphere, cylinder, and slab) and size (180 and 290 g) were prepared with agar (5%) and sucrose (5%). Dielectric constant (ε'), loss factor (ε"), thermophysical properties, and temperature distribution of the model system were measured. Each agar model system was immersed and suspended in water, and then, heated in a microwave oven with intermittent heating until the core temperature reached 50 °C. The ε' and ε" of agar gels decreased when frequency increased. The density and thermal conductivity values of the agar gels were 1033 kg/m(3) and 0.55 W/m °C, respectively. The temperature distribution of sphere, cylinder, and slab was different when similar power doses were applied. The slab reached 50 °C in less time (10 min) and showed a more uniform heating than spheres and cylinders in both sizes. Agar model systems of 180 g heated faster than those of 290 g. The coldest point was the center of the model systems in all studied cases. Shape and size are critical food factors that affect the heating uniformity during microwave heating processes.

  7. The effect of pulsed electric fields on carotenoids bioaccessibility: The role of tomato matrix.

    Science.gov (United States)

    Bot, Francesca; Verkerk, Ruud; Mastwijk, Hennie; Anese, Monica; Fogliano, Vincenzo; Capuano, Edoardo

    2018-02-01

    Tomato fractions were subjected to pulsed electric fields treatment combined or not with heating. Results showed that pulsed electric fields and heating applied in combination or individually induced permeabilization of cell membranes in the tomato fractions. However, no changes in β-carotene and lycopene bioaccessibility were found upon combined and individual pulsed electric fields and heating, except in the following cases: (i) in tissue, a significant decrease in lycopene bioaccessibility upon combined pulsed electric fields and heating and heating only was observed; (ii) in chromoplasts, both β-carotene and lycopene bioaccessibility significantly decreased upon combined pulsed electric fields and heating and pulsed electric fields only. The reduction in carotenoids bioaccessibility was attributed to modification in chromoplasts membrane and carotenoids-protein complexes. Differences in the effects of pulsed electric fields on bioaccessibility among different tomato fractions were related to tomato structure complexity. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Low-intensity pulsed ultrasound (LIPUS) and pulsed electromagnetic field (PEMF) treatments affect degeneration of cultured articular cartilage explants

    NARCIS (Netherlands)

    Tan, Lijun; Ren, Yijin; Kooten, van Theo G.; Grijpma, Dirk W.; Kuijer, Roel

    2015-01-01

    Purpose: Articular cartilage has some capacity for self-repair. Clinically used low-intensity pulsed ultrasound (LIPUS) and pulsed electromagnetic field (PEMF) treatments were compared in their potency to prevent degeneration using an explant model of porcine cartilage. Methods: Explants of porcine

  9. Decontamination of collagen biomatrices with combined pulsed electric field and nisin treatment.

    Science.gov (United States)

    Griffiths, Sarah; Maclean, Michelle; Macgregor, Scott J; Anderson, John G; Helen Grant, M

    2011-02-01

    Pulsed electric field (PEF) treatment has been proposed as a decontamination method for labile matrices used in tissue engineering applications. Through the application of PEF, a non-thermal treatment that causes bacterial inactivation through the irreversible rupture of microbial cell membranes, inactivation is achieved without loss of scaffold structure and function. However, some microorganisms are less susceptible to PEF treatment. This study shows that treatment with PEF and nisin, a food preservative bacteriocin, has a synergistic effect on the inactivation of Staphylococcus epidermidis in collagen gels. Almost complete inactivation of a 10(3) -10(4) CFU/mL S. epidermidis population was achieved when treated with a combination of PEF and 500 IU/mL nisin, with results demonstrating a 3.4 log(10) reduction, compared with 0.66 log(10) reduction with PEF alone. Nisin, at concentrations up to 3000 IU/mL, had no discernable toxicity to mammalian 3T3 cells when added to the culture medium or incorporated into the collagen gels. This combined decontamination method, involving PEF plus nisin, may provide a non-destructive process for inactivation of PEF-resistant bacteria in labile tissue engineering scaffolds.

  10. Crack formation under an electric field in droplets of laponite gel: memory effect and scaling relations.

    Science.gov (United States)

    Khatun, Tajkera; Dutta, Tapati; Tarafdar, Sujata

    2013-12-17

    When a colloidal gel dries through evaporation, cracks are usually formed, which often reveal underlying processes at work during desiccation. Desiccating colloid droplets of a few hundred microliters size show interesting effects of pattern formation and cracking which makes this an active subject of current research. Because aqueous gels of clay are known to be strongly affected by an electric field, one may expect crack patterns to exhibit a field effect. In the present study we allow droplets of laponite gel to dry under a radial electric field. This gives rise to highly reproducible patterns of cracks, which depend on the strength, direction, and time of exposure to the electric field. For a continuously applied DC voltage, cracks always appear on dissipation of a certain constant amount of energy. If the field is switched off before cracks appear, the observed results are shown to obey a number of empirical scaling relations, which enable us to predict the time of appearance and the number of cracks under specified conditions. Scanning electron microscopy (SEM) images of the surface between the macroscopic cracks show the presence of microcracks, which are wider and more numerous when no electric field is applied. The microcracks are reduced in the presence of stronger fields.

  11. Effects of pulsed electric fields on inactivation kinetics of Listeria innocua

    NARCIS (Netherlands)

    Wouters, P.C.; Dutreux, N.; Smelt, J.P.P.M.; Lelieveld, H.L.M.

    1999-01-01

    The effects of pulsed electric field (PEF) treatment and processing factors on the inactivation kinetics of Listeria innocua NCTC 11289 were investigated by using a pilot plant PEF unit with a flow rate of 200 liters/h. The electric field strength, pulse length, number of pulses, and inlet temperatu

  12. Vacuum magnetic linear birefringence using pulsed fields: the BMV experiment

    CERN Document Server

    Cadène, A; Fouché, M; Battesti, R; Rizzo, C

    2013-01-01

    In this letter we present the measurement of the vacuum magnetic birefringence obtained using the first generation setup of the BMV experiment. In particular, we detail our procedure of data acquisition and our analysis which takes into account the symmetry properties of raw data with respect to the orientation of the magnetic field and the sign of the cavity birefringence. Our current value of vacuum magnetic linear birefringence k_CM was obtained with about 100 magnetic pulses and a maximum field of 6.5 T. We get k_CM = (-7.4 \\pm 8.7).10^{-21} T^{-2} at 3 sigma confidence level. Our result is a clear validation of our innovative experimental method.

  13. [Research advances of anti-tumor immune response induced by pulse electric field ablation].

    Science.gov (United States)

    Cui, Guang-ying; Diao, Hong-yan

    2015-11-01

    As a novel tumor therapy, pulse electric field has shown a clinical perspective. This paper reviews the characteristics of tumor ablation by microsecond pulse and nanosecond pulse electric field, and the research advances of anti-tumor immune response induced by pulse electric field ablation. Recent researches indicate that the pulse electric field not only leads to a complete ablation of local tumor, but also stimulates a protective immune response, thereby inhibiting tumor recurrence and metastasis. These unique advantages will show an extensive clinical application in the future. However, the mechanism of anti-tumor immune response and the development of related tumor vaccine need further studies.

  14. Efficacy of fipronil gel over imlprothrin +cypermethrin aerosol in control of cockroaches (Field Trial

    Directory of Open Access Journals (Sweden)

    Vijender K Agrawal

    2012-01-01

    Full Text Available Background and Objectives: Cockroaches are offensive pests visually and expel unpleasant smelling secretion that spoils the flavor of food and environment. This trial was done to test Strikeout bait gel (fipronil 0.055% developed by Parijat Industries (India Pvt. Ltd. for its efficacy against Periplaneta americana and Blatella germanica, under field conditions in certain catering establishments of a city in Uttar Pradesh. Material and Methods: Ten catering establishments with high infestation based on pretreatment cockroach density assessment (Four for fipronil gel, four for imlprothrin+ cypermethrin aerosol and two without any treatment to act as a control were considered for inclusion in trial. Single application of fipronil gel/ imlprothrin+ cypermethrin aerosol was used as crack and crevice treatment. The visual assessment data for cockroach density in treatment and control catering establishments were considered for computation of percent reduction of cockroach infestation in the respective catering establishments. Results: Single application of fipronil gel was able to reduce cockroach infestation up to 96.0% at the end of 12 weeks whereas it was 20% in imlprothrin+ cypermethrin aerosol treated areas. Differences were found statistically significant. However, imlprothrin+ cypermethrin aerosol was more effective (52.0% in reducing the cockroach density by first week in comparison to fipronil gel (47.8% but its efficacy started declining after 5th week onwards. Interpretation and Conclusion: The study reports the efficacy of Strikeout bait gel (fipronil 0.055% for control of cockroaches in catering establishments. The application Strikeout bait gel (fipronil 0.055% was found more convenient to both operators and clients and there was minimal disruption at workplace.

  15. Inactivation of Ricin Toxin by Nanosecond Pulsed Electric Fields Including Evidences from Cell and Animal Toxicity

    Science.gov (United States)

    Wei, Kai; Li, Wei; Gao, Shan; Ji, Bin; Zang, Yating; Su, Bo; Wang, Kaile; Yao, Maosheng; Zhang, Jue; Wang, Jinglin

    2016-01-01

    Ricin is one of the most toxic and easily produced plant protein toxin extracted from the castor oil plant, and it has been classified as a chemical warfare agent. Here, nanosecond pulsed electric fields (nsPEFs) at 30 kV/cm (pulse durations: 10 ns, 100 ns, and 300 ns) were applied to inactivating ricin up to 4.2 μg/mL. To investigate the efficacy, cells and mice were tested against the ricin treated by the nsPEFs via direct intraperitoneal injection and inhalation exposure. Results showed that nsPEFs treatments can effectively reduce the toxicity of the ricin. Without the nsPEFs treatment, 100% of mice were killed upon the 4 μg ricin injection on the first day, however 40% of the mice survived the ricin treated by the nsPEFs. Compared to injection, inhalation exposure even with higher ricin dose required longer time to observe mice fatality. Pathological observations revealed damages to heart, lung, kidney, and stomach after the ricin exposure, more pronounced for lung and kidney including severe bleeding. Sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE) and circular dichroism (CD) analyses revealed that although the primary structure of ricin was not altered, its secondary structures (beta-sheet and beta-turn) underwent transition upon the nsPEFs treatment.

  16. Inactivation of Ricin Toxin by Nanosecond Pulsed Electric Fields Including Evidences from Cell and Animal Toxicity.

    Science.gov (United States)

    Wei, Kai; Li, Wei; Gao, Shan; Ji, Bin; Zang, Yating; Su, Bo; Wang, Kaile; Yao, Maosheng; Zhang, Jue; Wang, Jinglin

    2016-01-05

    Ricin is one of the most toxic and easily produced plant protein toxin extracted from the castor oil plant, and it has been classified as a chemical warfare agent. Here, nanosecond pulsed electric fields (nsPEFs) at 30 kV/cm (pulse durations: 10 ns, 100 ns, and 300 ns) were applied to inactivating ricin up to 4.2 μg/mL. To investigate the efficacy, cells and mice were tested against the ricin treated by the nsPEFs via direct intraperitoneal injection and inhalation exposure. Results showed that nsPEFs treatments can effectively reduce the toxicity of the ricin. Without the nsPEFs treatment, 100% of mice were killed upon the 4 μg ricin injection on the first day, however 40% of the mice survived the ricin treated by the nsPEFs. Compared to injection, inhalation exposure even with higher ricin dose required longer time to observe mice fatality. Pathological observations revealed damages to heart, lung, kidney, and stomach after the ricin exposure, more pronounced for lung and kidney including severe bleeding. Sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE) and circular dichroism (CD) analyses revealed that although the primary structure of ricin was not altered, its secondary structures (beta-sheet and beta-turn) underwent transition upon the nsPEFs treatment.

  17. MAGAT gel dosimetry for its application in small field treatment techniques

    Science.gov (United States)

    Gopishankar, N.; Vivekanandhan, S.; Kale, S. S.; Rath, G. K.; Senthil Kumaran, S.; Thulkar, Sanjay; Subramani, V.; Laviraj, M. A.; Bisht, R. K.; Mahapatra, A. K.

    2010-11-01

    Purpose of this work is to present the role of in-house manufactured MAGAT gel for treatment verification in small field dosimetric techniques such as Gammaknife (GK) and intensity-modulated radiation therapy (IMRT). Magnetic resonance imaging (MRI) is one of the most extensively used imaging technique for polymer gel dosimetry hence we used this method for gel evaluation. Different MR scanners and MRI sequences were used in this study for obtaining calibration plot between R2 and absorbed dose. An experimental plan was created for Gammaknife and IMRT. The prepared gel was filled in spherical glass phantom and in-house designed human head shape phantom for verification purpose. We used 8 TE values for all the imaging sequences for two reasons. Firstly it is sufficient enough to give good signal to noise ratio. Second considering the enormous scanning time involved in multiple spin echo sequence. MATLAB based in-house programs were used for R2 estimation and dose comparison. The isodose comparison with MAGAT gel showed reasonable agreement for both Gammaknife and IMRT techniques.

  18. Effects of pulsed electromagnetic fields on benign prostate hyperplasia.

    Science.gov (United States)

    Giannakopoulos, Xenophon K; Giotis, Christos; Karkabounas, Spyridon Ch; Verginadis, Ioannis I; Simos, Yannis V; Peschos, Dimitrios; Evangelou, Angelos M

    2011-12-01

    Benign prostate hyperplasia (BPH) has been treated with various types of electromagnetic radiation methods such as transurethral needle ablation (TUNA), interstitial laser therapy (ILC), holmium laser resection (HoLRP). In the present study, the effects of a noninvasive method based on the exposure of patients with BPH to a pulsative EM Field at radiofrequencies have been investigated. Twenty patients with BPH, aging 68-78 years old (y.o), were enrolled in the study. Patients were randomly divided into two groups: the treatment group (10 patients, 74.0 ± 5.7 y.o) treated with the α-blocker Alfusosin, 10 mg/24 h for at least 4 weeks, and the electromagnetic group (10 patients, 73.7 ± 6.3 y.o) exposed for 2 weeks in a very short wave duration, pulsed electromagnetic field at radiofrequencies generated by an ion magnetic inductor, for 30 min daily, 5 consecutive days per week. Patients of both groups were evaluated before and after drug and EMF treatment by values of total PSA and prostatic PSA fraction, acid phosphate, U/S estimation of prostate volume and urine residue, urodynamic estimation of urine flow rate, and International Prostate Symptom Score (IPSS). There was a statistically significant decrease before and after treatment of IPSS (P < 0.02), U/S prostate volume (P < 0.05), and urine residue (P < 0.05), as well as of mean urine flow rate (P < 0.05) in patients of the electromagnetic group, in contrast to the treatment group who had only improved IPSS (P < 0.05). There was also a significant improvement in clinical symptoms in patients of the electromagnetic group. Follow-up of the patients of this group for one year revealed that results obtained by EMFs treatment are still remaining. Pulsed electromagnetic field at radiofrequencies may benefit patients with benign prostate hyperplasia treated by a non-invasive method.

  19. Molecular epidemiologic study on pulsed-field gel electrophoresis genotyping of methicillin-resistant Staphylococcus aureus and outbreak of nosocomial infections%耐甲氧西林金黄色葡萄球菌PFGE分型与医院感染暴发的分子流行病学研究

    Institute of Scientific and Technical Information of China (English)

    许晓枫; 耿先龙; 周丽珍

    2015-01-01

    OBJECTIVE To analyze the homology among different strains and epidemiologic characteristics of methicillin‐resistant Staphylococcus aureus (MRSA) isolated from our hospital ,so as to guide prevention and control of nosocomial infections of MRSA .METHODS A total of S . aureus strains were identified by using Biomerieux VITEK‐2 automatic microbial analysis system from various specimens collected from all patients in the hospital from Jun .to Jul .2011 ,then the MRSA strains were confirmed according to the CLSI standard of cefoxitin KB method .The clinical strains were typed with pulsed‐field gel electrophoresis (PFGE) ,and epidemiological analysis was conducted .RESULTS The 36 MRSA strains displayed 6 kinds of genotypes and 8 kinds of subtypes , which was dominated by A genotype .During this research ,outbreak of MRSA infection occurred for two times in NICU and ICU .CONCLUSIONS MRSA might have a high possibility of causing cross‐infection in ICU wards and NICU wards ,while PFGE is a good research method for the study of nosocomial infection outbreak and its epidemiology .%目的:了解医院感染耐甲氧西林金黄色葡萄球菌(M RS A )的同源性及院内流行特征,为临床控制M RS A感染、制定合适的预防控制措施提供依据。方法收集2011年6-7月全院患者各类标本中分离出的M RS A 36株,金黄色葡萄球菌鉴定采用法国生物梅里埃公司的VIT EK‐2全自动微生物分析系统,根据美国CLSI标准用头孢西丁K‐B法确认M RSA ;运用脉冲场凝胶电泳(PFGE )对医院感染 M RSA进行基因分型,并进行流行病学分析。结果临床分离的36株 MRSA ,PFGE分型为6型8个亚型,其中以 A型为主;在研究期间,NICU 及ICU发生两次MRSA感染暴发。结论 MRSA在NICU及ICU易发生交叉感染;PFGE是医院感染暴发及流行病学的较好的研究手段。

  20. Experimental Study of SO2 Removal by Pulsed DBD Along with the Application of Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    RONG Ming-zhe; LIU Ding-xin; WANG Xiao-hua; WANG Jun-hua

    2007-01-01

    Dielectric barrier discharge (DBD) for SO2 removal from indoor air is investigated.In order to improve the removal efficiency,two novel methods are combined in this paper,namely by applying a pulsed driving voltage with nanosecond rising time and applying a magnetic field.For SO2 removal efficiency,different matches of electric field and magnetic field are discussed.And nanosecond rising edge pulsed power supply and microsecond rising edge pulsed power supply are compared.It can be concluded that a pulsed DBD with nanosecond rising edge should be adopted,and electrical field and magnetic field should be applied in an appropriate match.

  1. 临床标本分离表皮葡萄球菌的耐药性与脉冲场电泳分型研究%Drug resistance of Staphylococcus epidermidis isolates from clinical specimens and pulsed-field gel electrophoresis typing

    Institute of Scientific and Technical Information of China (English)

    周树生; 曹晓光; 戴媛媛; 王贤聪; 刘宝

    2015-01-01

    OBJECTIVE To explore the drug resistance of the Staphylococcus epidermidis causing infections in the ICU and analyze the molecular epidemiology so as to prevent the multidrug‐resistant bacteria infections .METHODS From Sep 2010 to Dec 2013 ,the drug susceptibility of 43 S .epidermidis isolates from the ICU was detected by u‐sing drug susceptibility testing techniques ,meanwhile ,the restriction endonuclease XbaI was used in chipping DNA extracted from all the strains ,which then were typed by the standardized pulsed‐field gel electrophoresis ap‐paratus ,and then the similarity was calculated among the studied strains with the PFGE molecular standards of Salmonella H9812 and BioNumerics (Version 4 .0)analysis software .RESULTS Totally nine PFGE types (A ,B , C ,D ,E ,F ,G ,H ,and I )were identified from the 43 S .epidermidis strains .Type A (20 strains ,46 .51% )and type C (12 strains ,27 .90% ) were the prevalent types ,three (6 .97% )strains were type E ;there were two (4 .65% ) strains of type D and two (4 .65% ) strains of type B ;there was 1 (2 .33% ) strain of another type and 1 (2 .33% ) strain of another type .The S .epidermidis strains showed various levels of resistance to the 13 antibiotics ,invol‐ving 23 drug resistance phenotypes ,with overlaps among them .The incidence of multidrug‐resistant organisms was as high as 62 .79% .CONCLUSION The pulsed‐field gel electrophoresis typing technique can be used to accu‐rately and rapidly trace the sources of nosocomial infections due to S .epidermidis strains .At the same time ,the incidence of multidrug‐resistant S .epidermidis is high in the ICU ,and it is necessary to strengthen the surveil‐lance of drug resistance and reasonably use antibiotics .%目的:探讨IC U表皮葡萄球菌感染的耐药性及分子流行病学特点,以防多药耐药菌感染发生。方法于2010年9月-2013年12月采用药物敏感性检测技术对IC U分离出的43株表皮葡萄球菌进行药物敏

  2. Intercomparison of radiation protection instrumentation in a pulsed neutron field

    Energy Technology Data Exchange (ETDEWEB)

    Caresana, M., E-mail: marco.caresana@polimi.it [Politecnico di Milano, CESNEF, Dipartimento di Energia, via Ponzio 34/3, 20133 Milano (Italy); Denker, A. [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany); Esposito, A. [IFNF-LNF, FISMEL, via E. Fermi 40, 00044 Frascati (Italy); Ferrarini, M. [CNAO, Via Privata Campeggi, 27100 Pavia (Italy); Golnik, N. [Institute of Metrology and Biomedical Engineering, Warsaw University of Technology, Sw. A. Boboli 8, 02-525 Warsaw (Poland); Hohmann, E. [Paul Scherrer Institut (PSI), Radiation Metrology Section, CH-5232 Villigen PSI (Switzerland); Leuschner, A. [Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22603 Hamburg (Germany); Luszik-Bhadra, M. [Physikalisch-Technische Bundesanstalt (PTB), Bundesallee 100, 38116 Braunschweig (Germany); Manessi, G. [CERN, 1211 Geneva 23 (Switzerland); University of Liverpool, Department of Physics, L69 7ZE Liverpool (United Kingdom); Mayer, S. [Paul Scherrer Institut (PSI), Radiation Metrology Section, CH-5232 Villigen PSI (Switzerland); Ott, K. [Helmholtz-Zentrum Berlin, BESSYII, Albert-Einstein-Str.15, 12489 Berlin (Germany); Röhrich, J. [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, D-14109 Berlin (Germany); Silari, M. [CERN, 1211 Geneva 23 (Switzerland); Trompier, F. [Institute for Radiological Protection and Nuclear Safety, F-92262 Fontenay aux Roses (France); Volnhals, M.; Wielunski, M. [Helmholtz Zentrum München, Ingolstädter Landstr. 1, D-85764 Neuherberg (Germany)

    2014-02-11

    In the framework of the EURADOS working group 11, an intercomparison of active neutron survey meters was performed in a pulsed neutron field (PNF). The aim of the exercise was to evaluate the performances of various neutron instruments, including commercially available rem-counters, personal dosemeters and instrument prototypes. The measurements took place at the cyclotron of the Helmholtz-Zentrum Berlin für Materialien und Energie GmbH. The cyclotron is routinely used for proton therapy of ocular tumours, but an experimental area is also available. For the therapy the machine accelerates protons to 68 MeV. The interaction of the proton beam with a thick tungsten target produces a neutron field with energy up to about 60 MeV. One interesting feature of the cyclotron is that the beam can be delivered in bursts, with the possibility to modify in a simple and flexible way the burst length and the ion current. Through this possibility one can obtain radiation bursts of variable duration and intensity. All instruments were placed in a reference position and irradiated with neutrons delivered in bursts of different intensity. The analysis of the instrument response as a function of the burst charge (the total electric charge of the protons in the burst shot onto the tungsten target) permitted to assess for each device the dose underestimation due to the time structure of the radiation field. The personal neutron dosemeters were exposed on a standard PMMA slab phantom and the response linearity was evaluated.

  3. Gravitational properties of light - The gravitational field of a laser pulse

    CERN Document Server

    Rätzel, Dennis; Menzel, Ralf

    2015-01-01

    The gravitational field of a laser pulse of finite lifetime, is investigated in the framework of linearized gravity. Although the effects are very small, they may be of fundamental physical interest. It is shown that the gravitational field of a linearly polarized light pulse is modulated as the norm of the corresponding electric field strength, while no modulations arise for circular polarization. In general, the gravitational field is independent of the polarization direction. It is shown that all physical effects are confined to spherical shells expanding with the speed of light, and that these shells are associated with the emission and absorption of the pulse. Nearby test particles at rest are attracted towards the pulse trajectory by the gravitational field due to the emission of the pulse, and they are repelled from the pulse trajectory by the gravitational field due to its absorption. Examples are given for the size of the attractive effect. It is recovered that massless test particles do not experien...

  4. Review of the Dynamics of Coalescence and Demulsification by High-Voltage Pulsed Electric Fields

    Directory of Open Access Journals (Sweden)

    Ye Peng

    2016-01-01

    Full Text Available The coalescence of droplets in oil can be implemented rapidly by high-voltage pulse electric field, which is an effective demulsification dehydration technological method. At present, it is widely believed that the main reason of pulse electric field promoting droplets coalescence is the dipole coalescence and oscillation coalescence in pulse electric field, and the optimal coalescence pulse electric field parameters exist. Around the above content, the dynamics of high-voltage pulse electric field promoting the coalescence of emulsified droplets is studied by researchers domestically and abroad. By review, the progress of high-voltage pulse electric field demulsification technology can get a better understanding, which has an effect of throwing a sprat to catch a whale on promoting the industrial application.

  5. [Research progress of nanosecond pulsed electric field applied to intracellular electromanipulation].

    Science.gov (United States)

    Yao, Chenguo; Mo, Dengbin; Sun, Caixin; Chen, Xin; Xiong, Zheng'ai

    2008-10-01

    In recent years, many experts have done some researches on experiment and mechanism of intracellular electromanipulation (IEM) under nanosecond pulsed electric field (nsPEF). The experiment results have shown that nsPEF could not induce electroporation of cell membrane, but could induce intracellular effects such as apoptosis, calcium release, enhancement of gene expression, and fragmentation of DNA and chromosome. In order to account for the phenomenon, researchers believe that when the pulse width of the pulsed electric field is larger than the charging time of plasma membrane, the pulsed electric field mainly targets on the outer membrane of cell; and that the effect of the pulsed electric field on nucleus and nuclear membrane increases with the decrease of the pulse width. It is also believed that the effect of electroporation changes from the outer membrane to intracellular electromanipulation when the pulse width decreases to a value being smaller than the charging time of plasma membrane.

  6. Transient electrical field across cellular membranes: pulsed electric field treatment of microbial cells

    Energy Technology Data Exchange (ETDEWEB)

    Timoshkin, I V [High Voltage Technologies Group, Institute for Energy and Environment, Department of Electronic and Electrical Engineering, University of Strathclyde, 204 George Street, Glasgow, G1 1XW (United Kingdom); MacGregor, S J [High Voltage Technologies Group, Institute for Energy and Environment, Department of Electronic and Electrical Engineering, University of Strathclyde, 204 George Street, Glasgow, G1 1XW (United Kingdom); Fouracre, R A [High Voltage Technologies Group, Institute for Energy and Environment, Department of Electronic and Electrical Engineering, University of Strathclyde, 204 George Street, Glasgow, G1 1XW (United Kingdom); Crichton, B H [High Voltage Technologies Group, Institute for Energy and Environment, Department of Electronic and Electrical Engineering, University of Strathclyde, 204 George Street, Glasgow, G1 1XW (United Kingdom); Anderson, J G [Robertson Trust Laboratory for Electronic Sterilization Technologies (ROLEST), Department of Electronic and Electrical Engineering, University of Strathclyde, 204 George Street, Glasgow, G1 1XW (United Kingdom)

    2006-02-07

    The pulsed electric field (PEF) treatment of liquid and pumpable products contaminated with microorganisms has attracted significant interest from the pulsed power and bioscience research communities particularly because the inactivation mechanism is non-thermal, thereby allowing retention of the original nutritional and flavour characteristics of the product. Although the biological effects of PEF have been studied for several decades, the physical mechanisms of the interaction of the fields with microorganisms is still not fully understood. The present work is a study of the dynamics of the electrical field both in a PEF treatment chamber with dielectric barriers and in the plasma (cell) membrane of a microbial cell. It is shown that the transient process can be divided into three physical phases, and models for these phases are proposed and briefly discussed. The complete dynamics of the time development of the electric field in a spherical dielectric shell representing the cellular membrane is then obtained using an analytical solution of the Ohmic conduction problem. It was found that the field in the membrane reaches a maximum value that could be two orders of magnitude higher than the original Laplacian electrical field in the chamber, and this value was attained in a time comparable to the field relaxation time in the chamber. Thus, the optimal duration of the field during PEF treatment should be equal to such a time.

  7. Analytical solution of precessional switching in nanomagnets driven by hard-axis field pulses

    Energy Technology Data Exchange (ETDEWEB)

    D' Aquino, M., E-mail: daquino@uniparthenope.it [Engineering Department, University of Naples “Parthenope”, 80143 Naples (Italy); Perna, S.; Serpico, C. [DIETI, University of Naples Federico II, 80125 Naples (Italy); Bertotti, G. [Istituto Nazionale di Ricerca Metrologica, 10135 Torino (Italy); Mayergoyz, I.D. [ECE Department and UMIACS, University of Maryland, College Park, MD, 20742 (United States); Quercia, A. [DIETI, University of Naples Federico II, 80125 Naples (Italy)

    2016-04-01

    The precessional switching process of a magnetic nanoparticle subject to external field pulses applied along the hard-axis is considered. The critical field pulse amplitude necessary to realize the switching is determined. Then, the analytical solution of magnetization switching dynamics is derived in the lossless limit by using elliptic functions. Moreover, expressions for the field pulse duration tolerances which guarantee successful switching are also obtained. The theoretical predictions are verified by macrospin numerical simulations of ultra-fast magnetization switching.

  8. GROWTH, INSTABILITY AND FORECASTING OF PIGEON PEA, CHICKPEA AND FIELD PEA PULSE PRODUCTION IN BANGLADESH

    OpenAIRE

    Rahman, Niaz Md. Farhat; Imam, M. F.

    2008-01-01

    The study tried to find out the appropriate models using latest model selection criteria that could describe the best growth pattern of pigeon pea, chickpea and field pea pulse production. The study also tried to measure the instability, growth rates of pigeon pea, chickpea and field pea pulse production and to determine the efficient time series models, to forecast the future pigeon pea, chickpea and field pea pulse production in Bangladesh. Forecasting attempts have been made to achieve the...

  9. Pulsed field magnetization strategies and the field poles composition in a bulk-type superconducting motor

    Science.gov (United States)

    Huang, Zhen; Ruiz, H. S.; Coombs, T. A.

    2017-03-01

    High temperature superconducting (HTS) bulks offer the potential of trapping and maintaining much higher magnetic loading level compared with the conventional permanent magnets used in rotary machines, although the effective magnetization of multiple HTS bulks with different relative orientations over the surface of cylindrical rotors creates new challenges. In this paper, we present the design and numerical validation of the Pulse Field Magnetization (PFM) strategy considered for the magnetization of the four-pole synchronous fully superconducting motor developed at the University of Cambridge. In a first instance, singular columns of up to five HTS bulks aligned over the height of the rotor were subjected to up to three magnetic pulses of 1.5 T peak, and the experimental results have been simulated by considering the electrical and thermal properties of the system in a 2D approach. The entire active surface of the rotor is covered by HTS bulks of approximately the same dimensions, resulting in an uneven distribution of pole areas with at least one of the poles formed by up to 3 columns of magnetized bulks, with relatively the same peaks of trapped magnetic field. Thus, in order to effectively use the entire area of the superconducting rotor, multiple pulsed fields per column have been applied under the same experimental conditions, what results in about three times larger magnetic pole areas but with an average drop on the peaks of trapped magnetic field of about 50%.

  10. Observation of enhanced field-free molecular alignment by two laser pulses

    DEFF Research Database (Denmark)

    Bisgaard, Christer; Poulsen, Mikael Dahlerup; Peronne, Emmanuel

    2004-01-01

    We show experimentally that field-free alignment of iodobenzene molecules, induced by a single, intense, linearly polarized 1.4-ps-long laser pulse, can be strongly enhanced by dividing the pulse into two optimally synchronized pulses of the same duration. For a given total energy of the two...

  11. Fast magnetic field annihilation driven by two laser pulses in underdense plasma

    Energy Technology Data Exchange (ETDEWEB)

    Gu, Y. J.; Kumar, D.; Weber, S.; Korn, G. [Institute of Physics of the ASCR, ELI-Beamlines, 18221 Prague (Czech Republic); Klimo, O. [Institute of Physics of the ASCR, ELI-Beamlines, 18221 Prague (Czech Republic); FNSPE, Czech Technical University in Prague, 11519 Prague (Czech Republic); Bulanov, S. V.; Esirkepov, T. Zh. [Kansai Photon Science Institute, Japan Atomic Energy Agency, 8-1-7 Umemidai, Kizugawa-shi, Kyoto 619-0215 (Japan)

    2015-10-15

    Fast magnetic annihilation is investigated by using 2.5-dimensional particle-in-cell simulations of two parallel ultra-short petawatt laser pulses co-propagating in underdense plasma. The magnetic field generated by the laser pulses annihilates in a current sheet formed between the pulses. Magnetic field energy is converted to an inductive longitudinal electric field, which efficiently accelerates the electrons of the current sheet. This new regime of collisionless relativistic magnetic field annihilation with a timescale of tens of femtoseconds can be extended to near-critical and overdense plasma with the ultra-high intensity femtosecond laser pulses.

  12. Manipulating antiferromagnets with magnetic fields: Ratchet motion of multiple domain walls induced by asymmetric field pulses

    Science.gov (United States)

    Gomonay, O.; Kläui, M.; Sinova, J.

    2016-10-01

    Future applications of antiferromagnets (AFs) in many spintronics devices rely on the precise manipulation of domain walls. The conventional approach using static magnetic fields is inefficient due to the low susceptibility of AFs. Recently proposed electrical manipulation with spin-orbit torques is restricted to metals with a specific crystal structure. Here, we propose an alternative, broadly applicable approach: using asymmetric magnetic field pulses to induce controlled ratchet motion of AF domain walls. The efficiency of this approach is based on three peculiarities of AF dynamics. First, a time-dependent magnetic field couples with an AF order parameter stronger than a static magnetic field, which leads to higher mobility of the domain walls. Second, the rate of change of the magnetic field couples with the spatial variation of the AF order parameter inside the domain, and this enables a synchronous motion of multiple domain walls with the same structure. Third, tailored asymmetric field pulses in combination with static friction can prevent backward motion of domain walls and thus lead to the desired controlled ratchet effect. The proposed use of an external field, rather than internal spin-orbit torques, avoids any restrictions on size, conductivity, and crystal structure of the AF material. We believe that our approach paves a way for the development of AF-based devices based on the controlled motion of AF domain walls.

  13. Investigation on stresses of superconductors under pulsed magnetic fields based on multiphysics model

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Xiaobin, E-mail: yangxb@lzu.edu.cn; Li, Xiuhong; He, Yafeng; Wang, Xiaojun; Xu, Bo

    2017-04-15

    Highlights: • The differential equation including temperature and magnetic field was derived for a long cylindrical superconductor. • Thermal stress and electromagnetic stress were studied at the same time under pulse field magnetizing. • The distributions of the magnetic field, the temperature and stresses are studied and compared for two pulse fields of the different duration. • The Role thermal stress and electromagnetic stress play in the process of pulse field magnetizing is discussed. - Abstract: A multiphysics model for the numerical computation of stresses, trapped field and temperature distribution of a infinite long superconducting cylinder is proposed, based on which the stresses, including the thermal stresses and mechanical stresses due to Lorentz force, and trapped fields in the superconductor subjected to pulsed magnetic fields are analyzed. By comparing the results under pulsed magnetic fields with different pulse durations, it is found that the both the mechanical stress due to the electromagnetic force and the thermal stress due to temperature gradient contribute to the total stress level in the superconductor. For pulsed magnetic field with short durations, the thermal stress is the dominant contribution to the total stress, because the heat generated by AC-loss builds up significant temperature gradient in such short durations. However, for a pulsed field with a long duration the gradient of temperature and flux, as well as the maximal tensile stress, are much smaller. And the results of this paper is meaningful for the design and manufacture of superconducting permanent magnets.

  14. Intercomparison of radiation protection instrumentation in a pulsed neutron field

    CERN Document Server

    Caresana, M; Esposito, A; Ferrarini, M; Golnik, N; Hohmann, E; Leuschner, A; Luszik-Bhadra, M; Manessi, G; Mayer, S; Ott, K; Röhrich, J; Silari, M; Trompier, F; Volnhals, M; Wielunski, M

    2014-01-01

    In the framework of the EURADOS working group 11, an intercomparison of active neutron survey meters was performed in a pulsed neutron field (PNF). The aim of the exercise was to evaluate the performances of various neutron instruments, including commercially available rem-counters, personal dosemeters and instrument prototypes. The measurements took place at the cyclotron of the Helmholtz-Zentrum Berlin für Materialien und Energie GmbH. The cyclotron is routinely used for proton therapy of ocular tumours, but an experimental area is also available. For the therapy the machine accelerates protons to 68 MeV. The interaction of the proton beam with a thick tungsten target produces a neutron field with energy up to about 60 MeV. One interesting feature of the cyclotron is that the beam can be delivered in bursts, with the possibility to modify in a simple and flexible way the burst length and the ion current. Through this possibility one can obtain radiation bursts of variable duration and intensity. All instru...

  15. In vitro exposure of human chondrocytes to pulsed electromagnetic fields

    Directory of Open Access Journals (Sweden)

    V Nicolin

    2009-08-01

    Full Text Available The effect of pulsed electromagnetic fields (PEMFs on the proliferation and survival of matrix-induced autologous chondrocyte implantation (MACI®-derived cells was studied to ascertain the healing potential of PEMFs. MACI-derived cells were taken from cartilage biopsies 6 months after surgery and cultured. No dedifferentiation towards the fibroblastic phenotype occurred, indicating the success of the surgical implantation. The MACI-derived cultured chondrocytes were exposed to 12 h/day (short term or 4 h/day (long term PEMFs exposure (magnetic field intensity, 2 mT; frequency, 75 Hz and proliferation rate determined by flow cytometric analysis. The PEMFs exposure elicited a significant increase of cell number in the SG2M cell cycle phase. Moreover, cells isolated from MACI® scaffolds showed the presence of collagen type II, a typical marker of chondrocyte functionality. The results show that MACI® membranes represent an optimal bioengineering device to support chondrocyte growth and proliferation in surgical implants. The surgical implant of MACI® combined with physiotherapy is suggested as a promising approach for a faster and safer treatment of cartilage traumatic lesions.

  16. Shaped pulse electric-field construction and interferometric characterization: The SPECIFIC method

    CERN Document Server

    Coughlan, Matthew A; Weber, Stefan M; Bowlan, Pamela; Trebino, Rick; Levis, Robert J

    2009-01-01

    A method is reported for creating, generating, and measuring parametrically shaped pulses for time-bandwidth product >>5, which consists of a parametric pulse-shaping algorithm, a spatial light modulation system and a single shot interferometric characterization scheme (SEA TADPOLE) . The utilization of these tools marks the inception of a new method called SPECIFIC, shaped-pulse electric-field construction and interferometric characterization, capable of producing complex shaped laser pulses for coherent control experiments.

  17. Pulsed Field Waveforms for Magnetization of HTS Gd-Ba-Cu-O Bulk Magnets

    Energy Technology Data Exchange (ETDEWEB)

    Ida, T [Department of Electronic Control Engineering, Hiroshima National College of Maritime Technology, 4272-1, Higashino, Ohsakikamijima-cho, Toyota-gun, Hiroshima 725-0231 (Japan); Matsuzaki, H [Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, 2-1-6, Etchu-jima, Koto-ku, Tokyo 135-8533 (Japan); Morita, E [Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, 2-1-6, Etchu-jima, Koto-ku, Tokyo 135-8533 (Japan); Sakashita, H [Department of Electronic Control Engineering, Hiroshima National College of Maritime Technology, 4272-1, Higashino, Ohsakikamijima-cho, Toyota-gun, Hiroshima 725-0231 (Japan); Harada, T [Department of Electronic Control Engineering, Hiroshima National College of Maritime Technology, 4272-1, Higashino, Ohsakikamijima-cho, Toyota-gun, Hiroshima 725-0231 (Japan); Ogata, H [Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, 2-1-6, Etchu-jima, Koto-ku, Tokyo 135-8533 (Japan); Kimura, Y [Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, 2-1-6, Etchu-jima, Koto-ku, Tokyo 135-8533 (Japan); Miki, M [Kitano Seiki Co. Ltd., 7-13-7, Chuo, Ohta-ku, Tokyo 143-0024 (Japan); Kitano, M [Kitano Seiki Co. Ltd., 7-13-7, Chuo, Ohta-ku, Tokyo 143-0024 (Japan); Izumi, M [Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, 2-1-6, Etchu-jima, Koto-ku, Tokyo 135-8533 (Japan)

    2006-06-01

    Progress in pulse magnetization technique for high-temperature superconductor bulks of melt-textured RE-Ba-Cu-O with large diameter is important for the realization of power applications. We studied the pulsed power source and pulsed field waveforms to enhance to improve the magnetization properties for Gd-Ba-Cu-O bulk. The risetime and duration of pulse waveform effectively varied distribution of magnetic flux.

  18. Effect of pulse magnetic field on solidification structure and properties of pure copper

    Institute of Scientific and Technical Information of China (English)

    LIAO Xi-liang; GONG Yong-yong; LI Ren-xing; CHEN Wen-jie; ZHAI Qi-jie

    2007-01-01

    The application of pulse magnetic field to metal solidification is an advanced technique which can remarkably refine solidification structure. In this paper, the effect of pulse magnetic field on solidification structure,mechanical properties and conductivity of pure copper was experimentally investigated. The results showed that the solidification structure transformed from coarse columnar crystal to fine globular crystal with increasing pulse voltage.Increasing pulse voltage also improved the tensile strength. However, with the increase of pulse voltage, the elongation and electrical resistivity firstly decreased, then increased when the pulse voltage beyond a critical value. Moreover,in some conditions, pulse magnetic field can simultaneously improve the conductivity and mechanical property of pure copper.

  19. In vivo setup characterization for pulsed electromagnetic field exposure at 3 GHz

    Science.gov (United States)

    Collin, A.; Perrin, A.; Cretallaz, C.; Pla, S.; Arnaud-Cormos, D.; Debouzy, J. C.; Leveque, P.

    2016-08-01

    An in vivo setup for pulsed electric field exposure at 3 GHz is proposed and characterized in this work. The exposure system allows far field, whole-body exposure of six animals placed in Plexiglas cages with a circular antenna. Chronic exposures under 18 W incident average power (1-4 kW peak power) and acute exposures under 56 W incident average power (4.7 kW peak power) were considered. Numerical and experimental dosimetry of the setup allowed the accurate calculation of specific absorption rate (SAR) distributions under various exposure conditions. From rat model numerical simulations, the whole-body mean SAR values were 1.3 W kg-1 under chronic exposures and 4.1 W kg-1 under acute exposure. The brain-averaged SAR value was 1.8 W kg-1 and 5.7 W kg-1 under chronic and acute exposure, respectively. Under acute exposure conditions, a 10 g specific absorption of 1.8  ±  1.1 mJ · kg-1 value was obtained. With temperature rises below 0.8 °C, as measured or simulated on a gel phantom under typical in vivo exposures, this exposure system provides adequate conditions for in vivo experimental investigations under non-thermal conditions.

  20. Improving carotenoid extraction from tomato waste by pulsed electric fields.

    Directory of Open Access Journals (Sweden)

    Elisa eLuengo

    2014-08-01

    Full Text Available In this investigation, the influence of the application of Pulsed Electric Fields (PEF of different intensities (3-7 kV/cm and 0-300 μs on the carotenoid extraction from tomato peel and pulp in a mixture of hexane:acetone:ethanol was studied with the aim of increasing extraction yield or reducing the percentage of the less green solvents in the extraction medium. According to the cellular disintegration index, the optimum treatment time for the permeabilization of tomato peel and pulp at different electric field strengths was 90 µs. The PEF permeabilization of tomato pulp did not significantly increase the carotenoid extraction. However, a PEF-treatment at 5 kV/cm improved the carotenoid extraction from tomato peel by 39 % as compared with the control in a mixture of hexane:ethanol:acetone (50:25:25. Further increments of electric field from 5 to 7 kV/cm did not increase significantly the extraction of carotenoids. . The presence of acetone in the solvent mixture did not positively affect the carotenoid extraction when the tomato peels were PEF-treated. Response surface methodology was used to determine the potential of PEF for reducing the percentage of hexane in a hexane:ethanol mixture. The application of a PEF-treatment allowed reducing the hexane percentage from 45 to 30 % without affecting the carotenoid extraction yield. The antioxidant capacity of the extracts obtained from tomato peel was correlated with the carotenoid concentration and it was not affected by the PEF-treatment.

  1. Using electric fields for pulse compression and group velocity control

    CERN Document Server

    Li, Qian; Thuresson, Axel; Rippe, Lars; Kröll, Stefan

    2016-01-01

    In this article, we experimentally demonstrate a new way of controlling the group velocity of an optical pulse by using a combination of spectral hole burning, slow light effect and linear Stark effect in a rare-earth-ion-doped crystal. The group velocity can be changed continuously by a factor of 20 without significant pulse distortion or absorption of the pulse energy. With a similar technique, an optical pulse can also be compressed in time. Theoretical simulations were developed to simulate the group velocity control and the pulse compression processes. The group velocity as well as the pulse reshaping are solely controlled by external voltages which makes it promising in quantum information and quantum communication processes. It is also proposed that the group velocity can be changed even more in an Er doped crystal while at the same time having a transmission band matching the telecommunication wavelength.

  2. Pulsed-field capillary electrophoresis: optimizing separation parameters with model mixtures of sulfonated polystyrenes.

    Science.gov (United States)

    Sudor, J; Novotny, M V

    1994-07-01

    The electrophoretic transport of high molecular weight charged solutes, both flexible and stiff polymers, has been studied by capillary electrophoresis under constant-field and pulsed-field conditions. Sulfonated polystyrenes were used as model solutes in different entangled polymer solutions. First, changes of the end-to-end distance vectors of flexible polymers were examined through the mobility/potential-gradient curves. Under pulsed-field conditions, the influence of different pulse shapes, frequencies, and amplitudes of forward and backward pulses on the electrophoretic mobilities of model solutes was studied. Resolution of the mixture components was strongly affected by changes in frequency of both sine-wave and square-wave pulses. The experimental results obtained under pulse-field conditions are roughly in agreement with the existing theories of electrophoretic transport.

  3. Commercial scale pulsed electric field processing of tomato juice.

    Science.gov (United States)

    Min, Seacheol; Jin, Z Tony; Zhang, Q Howard

    2003-05-21

    Effects of commercial scale pulsed electric field (PEF) processing on the quality of tomato juice were studied and compared with those of thermal processing. Tomato juice was prepared by hot break at 88 degrees C for 2 min or by cold break at 68 degrees C for 2 min and then thermally processed at 92 degrees C for 90 s or PEF processed at 40 kV/cm for 57 micros. Thermally processed, PEF processed, and unprocessed control juices were packed into 50 mL sterilized polypropylene tubes in a sanitary glovebox and stored at 4 degrees C for 112 days. Both thermally and PEF processed juices showed microbial shelf life at 4 degrees C for 112 days. The lipoxygenase activities of thermally and PEF processed juices were 0 and 47%, respectively. PEF processed juice retained more ascorbic acid than thermally processed juice at 4 degrees C for 42 days (p Brix, pH, or viscosity between thermally and PEF processed juices during the storage (p > 0.05). Sensory evaluations indicated that flavor and overall acceptability of PEF processed juice were preferred to those of thermally processed juice (p < 0.05).

  4. Effects of pulsed electromagnetic fields on postmenopausal osteoporosis.

    Science.gov (United States)

    Zhu, Siyi; He, Hongchen; Zhang, Chi; Wang, Haiming; Gao, Chengfei; Yu, Xijie; He, Chengqi

    2017-09-01

    Postmenopausal osteoporosis (PMOP) is considered to be a well-defined subject that has caused high morbidity and mortality. In elderly women diagnosed with PMOP, low bone mass and fragile bone strength have been proven to significantly increase risk of fragility fractures. Currently, various anabolic and anti-resorptive therapies have been employed in an attempt to retain healthy bone mass and strength. Pulsed electromagnetic fields (PEMFs), first applied in treating patients with delayed fracture healing and nonunions, may turn out to be another potential and effective therapy for PMOP. PEMFs can enhance osteoblastogenesis and inhibit osteoclastogenesis, thus contributing to an increase in bone mass and strength. However, accurate mechanisms of the positive effects of PEMFs on PMOP remain to be further elucidated. This review attempts to summarize recent advances of PEMFs in treating PMOP based on clinical trials, and animal and cellular studies. Possible mechanisms are also introduced, and the future possibility of application of PEMFs on PMOP are further explored and discussed. Bioelectromagnetics. 38:406-424, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  5. Investigation of dose distribution in mixed neutron-gamma field of boron neutron capture therapy using N isopropylacrylamide gel

    Energy Technology Data Exchange (ETDEWEB)

    Bavarmegin, Elham; Sadremomtaz, Alireza [Nuclear Science and Technology Research Institute (NSTRI), Tehran (Iran, Islamic Republic of); Khalafi, Hossein; Kasesaz, Yaser [Dept. of Physics, University of Guilan, Rasht (Iran, Islamic Republic of); Khajeali, Azim [Medical Education Research Center, Tabriz (Iran, Islamic Republic of)

    2017-02-15

    Gel dosimeters have unique advantages in comparison with other dosimeters. Until now, these gels have been used in different radiotherapy techniques as a reliable dosimetric tool. Because dose distribution measurement is an important factor for appropriate treatment planning in different radiotherapy techniques, in this study, we evaluated the ability of the N-isopropylacrylamide (NIPAM) polymer gel to record the dose distribution resulting from the mixed neutron-gamma field of boron neutron capture therapy (BNCT). In this regard, a head phantom containing NIPAM gel was irradiated using the Tehran Research Reactor BNCT beam line, and then by a magnetic resonance scanner. Eventually, the R2 maps were obtained in different slices of the phantom by analyzing T2-weighted images. The results show that NIPAM gel has a suitable potential for recording three-dimensional dose distribution in mixed neutron-gamma field dosimetry.

  6. Investigation of Dose Distribution in Mixed Neutron-Gamma Field of Boron Neutron Capture Therapy using N-Isopropylacrylamide Gel

    Directory of Open Access Journals (Sweden)

    Elham Bavarnegin

    2017-02-01

    Full Text Available Gel dosimeters have unique advantages in comparison with other dosimeters. Until now, these gels have been used in different radiotherapy techniques as a reliable dosimetric tool. Because dose distribution measurement is an important factor for appropriate treatment planning in different radiotherapy techniques, in this study, we evaluated the ability of the N-isopropylacrylamide (NIPAM polymer gel to record the dose distribution resulting from the mixed neutron-gamma field of boron neutron capture therapy (BNCT. In this regard, a head phantom containing NIPAM gel was irradiated using the Tehran Research Reactor BNCT beam line, and then by a magnetic resonance scanner. Eventually, the R2 maps were obtained in different slices of the phantom by analyzing T2-weighted images. The results show that NIPAM gel has a suitable potential for recording three-dimensional dose distribution in mixed neutron-gamma field dosimetry.

  7. Research on Nanosecond Pulse Corona Discharge with Cross Magnetic Field Applied

    Institute of Scientific and Technical Information of China (English)

    HE Zheng-hao; YU Fu-sheng; HU Feng; YUAN Yun; GUO Li-na; LI Jin

    2007-01-01

    An application of magnetic field to the nanosecond pulse corona discharge is investigated.A cylinder reactor with different corona electodes is set up for experimental study.A manetic field with its direction perpendicular to the corona discharge is applied.Different discharge images are taken under single nanosecond pulse with a high sensitive UV-visible light imagine recorder.Experimental results show that with a cross magnetic field the nanosecond out the magnetic field. The results may lead to a possibility to apply a cross magnetic field on nanosecond pulse corona discharge for getting higher desulfurization effciency.

  8. A new pulsed electric field microreactor: comparison between the laboratory and microtechnology scale

    NARCIS (Netherlands)

    Fox, Martijn; Esveld, Erik; Luttge, Regina; Boom, Remko

    2005-01-01

    This paper presents a new microreactor dedicated for pulsed electric field treatment (PEF), which is a pasteurization method that inactivates microorganisms with short electric pulses. The PEF microreactor consists of a flow-through channel with a constriction where the electric field is focussed. C

  9. Field Testing Pulsed Power Inverters in Welding Operations to Control Heavy Metal Emissions

    Science.gov (United States)

    2009-12-01

    FINAL REPORT Field Testing Pulsed Power Inverters in Welding Operations to Control Heavy Metal Emissions ESTCP Project WP-200212...PROGRAM ELEMENT NUMBER Field Testing Pulsed Power Inverters in Welding Operations to Control Heavy Metal Emissions 6. AUTHOR(S) 5d. PROJECT

  10. Toward 6 log10 pulsed electric field inactivation with conductive plastic packaging material

    NARCIS (Netherlands)

    Roodenburg, B.; Haan, S.W.H. de; Ferreira, J.A.; Coronel, P.; Wouters, P.C.; Hatt, V.

    2013-01-01

    Generally, high grade products such as pulsed electric field (PEF) treated fruit juices are packaged after their preservative treatment. However, PEF treatment after packaging could avoid recontamination of the product and becomes feasible when electric field pulses of sufficient magnitude can be ge

  11. Toward 6 log10 pulsed electric field inactivation with conductive plastic packaging material

    NARCIS (Netherlands)

    Roodenburg, B.; Haan, S.W.H. de; Ferreira, J.A.; Coronel, P.; Wouters, P.C.; Hatt, V.

    2013-01-01

    Generally, high grade products such as pulsed electric field (PEF) treated fruit juices are packaged after their preservative treatment. However, PEF treatment after packaging could avoid recontamination of the product and becomes feasible when electric field pulses of sufficient magnitude can be

  12. The influence of laser pulse on the photoabsorption spectra of Li atom in strong external field

    Institute of Scientific and Technical Information of China (English)

    WANG; Dehua; LIN; Shenglu

    2006-01-01

    Using the time-dependent perturbation theory and the calculation formula of the single- and double-pulse absorption spectra of the atom in strong external fields, we calculate the single- and double-pulse absorption spectra of Li atom in strong magnetic field for different pulse widths. The results show that a pulse of some width can reduce the contribution of the short period closed orbits and eliminate the contribution of the long period orbits. Compared with the single-pulse absorption spectra, we found that for some phase differences, the double-pulse laser absorption spectra are strengthened; while for others, they are reduced. Therefore, we can use the pulse laser to control the oscillation of the absorption spectra and obtain the optimization object.

  13. Pulse

    Science.gov (United States)

    ... resting for at least 10 minutes. Take the exercise heart rate while you are exercising. ... pulse rate can help determine if the person's heart is pumping. Pulse ... rate gives information about your fitness level and health.

  14. Strong Static Magnetic Fields Increase the Gel Signal in Partially Hydrated DPPC/DMPC Membranes

    Directory of Open Access Journals (Sweden)

    Jennifer Tang

    2015-09-01

    Full Text Available NIt was recently reported that static magnetic fields increase lipid order in the hydrophobic membrane core of dehydrated native plant plasma membranes [Poinapen, Soft Matter 9:6804-6813, 2013]. As plasma membranes are multicomponent, highly complex structures, in order to elucidate the origin of this effect, we prepared model membranes consisting of a lipid species with low and high melting temperature. By controlling the temperature, bilayers coexisting of small gel and fluid domains were prepared as a basic model for the plasma membrane core. We studied molecular order in mixed lipid membranes made of dimyristoyl-sn-glycero-3-phosphocholine (DMPC and dipalmitoyl-sn-glycero-3-phosphocholine (DPPC using neutron diffraction in the presence of strong static magnetic fields up to 3.5 T. The contribution of the hydrophobic membrane core was highlighted through deuterium labeling the lipid acyl chains. There was no observable effect on lipid organization in fluid or gel domains at high hydration of the membranes. However, lipid order was found to be enhanced at a reduced relative humidity of 43%: a magnetic field of 3.5 T led to an increase of the gel signal in the diffraction patterns of 5%. While all biological materials have weak diamagnetic properties, the corresponding energy is too small to compete against thermal disorder or viscous effects in the case of lipid molecules. We tentatively propose that the interaction between the fatty acid chains’ electric moment and the external magnetic field is driving the lipid tails in the hydrophobic membrane core into a better ordered state.

  15. A 7 T Pulsed Magnetic Field Generator for Magnetized Laser Plasma Experiments

    Science.gov (United States)

    Hu, Guangyue; Liang, Yihan; Song, Falun; Yuan, Peng; Wang, Yulin; Zhao, Bin; Zheng, Jian

    2015-02-01

    A pulsed magnetic field generator was developed to study the effect of a magnetic field on the evolution of a laser-generated plasma. A 40 kV pulsed power system delivered a fast (~230 ns), 55 kA current pulse into a single-turn coil surrounding the laser target, using a capacitor bank of 200 nF, a laser-triggered switch and a low-impedance strip transmission line. A one-dimensional uniform 7 T pulsed magnetic field was created using a Helmholtz coil pair with a 6 mm diameter. The pulsed magnetic field was controlled to take effect synchronously with a nanosecond heating laser beam, a femtosecond probing laser beam and an optical Intensified Charge Coupled Device (ICCD) detector. The preliminary experiments demonstrate bifurcation and focusing of plasma expansion in a transverse magnetic field.

  16. Considerations concerning the use of counting active personal dosimeters in pulsed fields of ionising radiation.

    Science.gov (United States)

    Ambrosi, Peter; Borowski, Markus; Iwatschenko, Michael

    2010-06-01

    Active personal electronic dosimeters (APDs) exhibit limitations in pulsed radiation fields, which cannot be overcome without the use of new detection technology. As an interim solution, this paper proposes a method by which some conventional dosimeters can be operated in a way such that, based on the basic knowledge about the pulsed radiation field, any dosimetric failure of the dosimeter is signalised by the instrument itself. This method is not applicable to all combinations of APD and pulsed radiation field. The necessary requirements for the APD and for the parameters of the pulsed radiation field are given in the paper. Up to now, all such requirements for APDs have not been tested or verified in a type test. The suitability of the method is verified for the use of one APD used in two clinical pulsed fields.

  17. Nanosecond pulsed electric fields and the cell cycle

    Science.gov (United States)

    Mahlke, Megan A.

    Exposure to nanosecond pulsed electrical fields (nsPEFs) can cause poration of external and internal cell membranes, DNA damage, and disassociation of cytoskeletal components, all of which are capable of disrupting a cell's ability to replicate. The phase of the cell cycle at the time of exposure is linked to differential sensitivities to nsPEFs across cell lines, as DNA structure, membrane elasticity, and cytoskeletal structure change dramatically during the cell cycle. Additionally, nsPEFs are capable of activating cell cycle checkpoints, which could lead to apoptosis or slow population growth. NsPEFs are emerging as a method for treating tumors via apoptotic induction; therefore, investigating the relevance of nsPEFs and the cell cycle could translate into improved efficacy in tumor treatment. Populations of Jurkat and Chinese Hamster Ovary (CHO) cells were examined post-exposure (10 ns pulse trains at 150kV/cm) by analysis of DNA content via propidium iodide staining and flow cytometric analysis at various time points (1, 6, and 12h post-exposure) to determine population distribution in cell cycle phases. Additionally, CHO and Jurkat cells were synchronized in G1/S and G2/M phases, pulsed, and analyzed to evaluate the role of cell cycle phase in survival of nsPEFs. CHO populations appeared similar to sham populations post-nsPEFs but exhibited arrest in the G1 phase at 6h after exposure. Jurkat cells exhibited increased cell death after nsPEFs compared to CHO cells but did not exhibit checkpoint arrest at any observed time point. The G1/S phase checkpoint is partially controlled by the action of p53; the lack of an active p53 response in Jurkat cells could contribute to their ability to pass this checkpoint and resist cell cycle arrest. Both cell lines exhibited increased sensitivity to nsPEFs in G2/M phase. Live imaging of CHO cells after nsPEF exposure supports the theory of G1/S phase arrest, as a reduced number of cells undergo mitosis within 24 h when

  18. Tailored RF pulse optimization for magnetization inversion at ultra high field

    CERN Document Server

    Hurley, Aaron C; Li, Bai; Aickelin, Uwe; Coxon, Ron; Glover, Paul; Gowland, Penny A

    2010-01-01

    The radiofrequency (RF) transmit field is severely inhomogeneous at ultrahigh field due to both RF penetration and RF coil design issues. This particularly impairs image quality for sequences that use inversion pulses such as magnetization prepared rapid acquisition gradient echo and limits the use of quantitative arterial spin labeling sequences such as flow-attenuated inversion recovery. Here we have used a search algorithm to produce inversion pulses tailored to take into account the heterogeneity of the RF transmit field at 7 T. This created a slice selective inversion pulse that worked well (good slice profile and uniform inversion) over the range of RF amplitudes typically obtained in the head at 7 T while still maintaining an experimentally achievable pulse length and pulse amplitude in the brain at 7 T. The pulses used were based on the frequency offset correction inversion technique, as well as time dilation of functions, but the RF amplitude, frequency sweep, and gradient functions were all generate...

  19. Characteristics and Antitumor Activity of Morchella esculenta Polysaccharide Extracted by Pulsed Electric Field

    Directory of Open Access Journals (Sweden)

    Chao Liu

    2016-06-01

    Full Text Available Polysaccharides from Morchella esculenta have been proven to be functional and helpful for humans. The purpose of this study was to investigate the chemical structure and anti-proliferating and antitumor activities of a Morchella esculenta polysaccharide (MEP extracted by pulsed electric field (PEF in submerged fermentation. The endo-polysaccharide was separated and purified by column chromatography and Gel permeation chromatography, and analyzed by gas chromatography. The MEP with an average molecular weight of 81,835 Da consisted of xylose, glucose, mannose, rhamnose and galactose at the ratio of 5.4:5.0:6.5:7.8:72.3. Structure of MEP was further analyzed by Fourier-transform infrared spectroscopy and 1H and 13C liquid-state nuclear magnetic resonance spectroscopy. Apoptosis tests proved that MEP could inhibit the proliferation and growth of human colon cancer HT-29 cells in a time- and dose-dependent manner within 48 h. This study provides more information on chemical structure of anti-proliferating polysaccharides isolated from Morchella esculenta.

  20. Characteristics and Antitumor Activity of Morchella esculenta Polysaccharide Extracted by Pulsed Electric Field.

    Science.gov (United States)

    Liu, Chao; Sun, Yonghai; Mao, Qian; Guo, Xiaolei; Li, Peng; Liu, Yang; Xu, Na

    2016-06-22

    Polysaccharides from Morchella esculenta have been proven to be functional and helpful for humans. The purpose of this study was to investigate the chemical structure and anti-proliferating and antitumor activities of a Morchella esculenta polysaccharide (MEP) extracted by pulsed electric field (PEF) in submerged fermentation. The endo-polysaccharide was separated and purified by column chromatography and Gel permeation chromatography, and analyzed by gas chromatography. The MEP with an average molecular weight of 81,835 Da consisted of xylose, glucose, mannose, rhamnose and galactose at the ratio of 5.4:5.0:6.5:7.8:72.3. Structure of MEP was further analyzed by Fourier-transform infrared spectroscopy and ¹H and (13)C liquid-state nuclear magnetic resonance spectroscopy. Apoptosis tests proved that MEP could inhibit the proliferation and growth of human colon cancer HT-29 cells in a time- and dose-dependent manner within 48 h. This study provides more information on chemical structure of anti-proliferating polysaccharides isolated from Morchella esculenta.

  1. Characteristics and Antitumor Activity of Morchella esculenta Polysaccharide Extracted by Pulsed Electric Field

    Science.gov (United States)

    Liu, Chao; Sun, Yonghai; Mao, Qian; Guo, Xiaolei; Li, Peng; Liu, Yang; Xu, Na

    2016-01-01

    Polysaccharides from Morchella esculenta have been proven to be functional and helpful for humans. The purpose of this study was to investigate the chemical structure and anti-proliferating and antitumor activities of a Morchella esculenta polysaccharide (MEP) extracted by pulsed electric field (PEF) in submerged fermentation. The endo-polysaccharide was separated and purified by column chromatography and Gel permeation chromatography, and analyzed by gas chromatography. The MEP with an average molecular weight of 81,835 Da consisted of xylose, glucose, mannose, rhamnose and galactose at the ratio of 5.4:5.0:6.5:7.8:72.3. Structure of MEP was further analyzed by Fourier-transform infrared spectroscopy and 1H and 13C liquid-state nuclear magnetic resonance spectroscopy. Apoptosis tests proved that MEP could inhibit the proliferation and growth of human colon cancer HT-29 cells in a time- and dose-dependent manner within 48 h. This study provides more information on chemical structure of anti-proliferating polysaccharides isolated from Morchella esculenta. PMID:27338370

  2. Generation of flat-top pulsed magnetic fields with feedback control approach

    CERN Document Server

    Kohama, Yoshimitsu

    2015-01-01

    We describe the construction of a simple, compact, and cost-effective feedback system that produces flat-top field profiles in pulsed magnetic fields. This system is designed for use in conjunction with a typical capacitor-bank driven pulsed magnet, and was tested using a 60-T pulsed magnet. With the developed feedback controller, we have demonstrated flat-top magnetic fields as high as 60.64 T with an excellent field stability of +-0.005 T. The result indicates that the flat-top pulsed magnetic field produced features high field stability and an accessible field strength. These features make this system useful for improving the resolution of data with signal averaging.

  3. Pulsed field magnetization strategies and the field poles composition in a bulk-type superconducting motor

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Zhen, E-mail: zhen.huang@sjtu.edu.cn [Academy of Information Technology and Electrical Engineering, Shanghai Jiao Tong University, 800 Dongchuan Road, Shanghai 200240 (China); Ruiz, H.S., E-mail: dr.harold.ruiz@le.ac.uk [Department of Engineering, University of Leicester, University Road, Leicester LE1 7RH (United Kingdom); Coombs, T.A., E-mail: tac1000@cam.ac.uk [Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA (United Kingdom)

    2017-03-15

    Highlights: • Different compositions of the magnetic poles have been obtained depending on the relative orientation of the magnetizing coil and the surfaces of the columns of bulks that conform a magnetic pole. • Two bidimensional models accounting for the electromagnetic response of the top and lateral cross sections of three columns of HTS bulks subjected to multiple pulsed magnetic fields have been created. • An extended PFM strategy has been proposed by considering the magnetization of at least three successive columns of HTS bulks per pole. In the extended PFM strategy the area of each one of the poles can be seen increased by a factor of 200%-400% - Abstract: High temperature superconducting (HTS) bulks offer the potential of trapping and maintaining much higher magnetic loading level compared with the conventional permanent magnets used in rotary machines, although the effective magnetization of multiple HTS bulks with different relative orientations over the surface of cylindrical rotors creates new challenges. In this paper, we present the design and numerical validation of the Pulse Field Magnetization (PFM) strategy considered for the magnetization of the four-pole synchronous fully superconducting motor developed at the University of Cambridge. In a first instance, singular columns of up to five HTS bulks aligned over the height of the rotor were subjected to up to three magnetic pulses of 1.5 T peak, and the experimental results have been simulated by considering the electrical and thermal properties of the system in a 2D approach. The entire active surface of the rotor is covered by HTS bulks of approximately the same dimensions, resulting in an uneven distribution of pole areas with at least one of the poles formed by up to 3 columns of magnetized bulks, with relatively the same peaks of trapped magnetic field. Thus, in order to effectively use the entire area of the superconducting rotor, multiple pulsed fields per column have been applied

  4. Small field dose delivery evaluations using cone beam optical computed tomography-based polymer gel dosimetry

    Directory of Open Access Journals (Sweden)

    Timothy Olding

    2011-01-01

    Full Text Available This paper explores the combination of cone beam optical computed tomography with an N-isopropylacrylamide (NIPAM-based polymer gel dosimeter for three-dimensional dose imaging of small field deliveries. Initial investigations indicate that cone beam optical imaging of polymer gels is complicated by scattered stray light perturbation. This can lead to significant dosimetry failures in comparison to dose readout by magnetic resonance imaging (MRI. For example, only 60% of the voxels from an optical CT dose readout of a 1 l dosimeter passed a two-dimensional Low′s gamma test (at a 3%, 3 mm criteria, relative to a treatment plan for a well-characterized pencil beam delivery. When the same dosimeter was probed by MRI, a 93% pass rate was observed. The optical dose measurement was improved after modifications to the dosimeter preparation, matching its performance with the imaging capabilities of the scanner. With the new dosimeter preparation, 99.7% of the optical CT voxels passed a Low′s gamma test at the 3%, 3 mm criteria and 92.7% at a 2%, 2 mm criteria. The fitted interjar dose responses of a small sample set of modified dosimeters prepared (a from the same gel batch and (b from different gel batches prepared on the same day were found to be in agreement to within 3.6% and 3.8%, respectively, over the full dose range. Without drawing any statistical conclusions, this experiment gives a preliminary indication that intrabatch or interbatch NIPAM dosimeters prepared on the same day should be suitable for dose sensitivity calibration.

  5. Control of the polarization of attosecond pulses using a two-color field

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz, Camilo; Hoffmann, David J; Torres, Ricardo; Chipperfield, Luke E; Marangos, Jonathan P [Blackett Laboratory, Imperial College London, London SW7 2BW (United Kingdom)], E-mail: camilo@usal.es

    2009-11-15

    Control over the polarization of an attosecond pulse train (APT) is demonstrated theoretically using orthogonally polarized two-color fields. The carrier envelope phase of the two pulses is used as a control parameter to generate both an APT with linear polarization in two nearly perpendicular planes or a train of elliptically polarized pulses of alternating helicity. By using few-cycle driving laser fields an isolated attosecond pulse with elliptical polarization is shown to be generated after selecting the cut-off region of the harmonic spectrum. The control mechanism is explained in terms of classical trajectories.

  6. Investigation of the behavior of protection elements against field radiated line coupled UWB-pulses

    Directory of Open Access Journals (Sweden)

    R. Krzikalla

    2006-01-01

    Full Text Available To protect electronic systems against electromagnetic interferences in general nonlinear protection circuits are used. These protection circuits are optimized mostly against special transient interferences such as lightning electromagnetic pulses (LEMP or electromagnetic pulses caused by nuclear explosions (NEMP. Previous investigations have shown that these protection elements could be undermined by so-called ultra wideband (UWB pulses. Thereby a direct charge of the UWB-pulse to the elements has been assumed. This assumption was a worst case approximation because in practice UWB-pulses only get into systems by coupling effects. In this investigation the behavior of typical nonlinear protection elements has been tested with field radiated line coupled UWB-pulses. For that line coupled UWB-pulses have been defined depending on the coupling behavior of typical electronic systems and a possibility of generation of this kind of pulses is presented. After it typical nonlinear protection elements such as spark gaps, varistors and protection diodes have been tested with the previously defined test pulses. Finally the measured behavior of the elements has been compared with the behavior by direct charged UWB-pulses and the protection effect of the elements against field radiated line coupled UWB-pulses is re-evaluated.

  7. Analysis of Graphite Morphology of Gray Cast Iron in Pulse Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    LI Qiu-shu; LIU Li-qiang; ZHAI Qi-jie

    2005-01-01

    By self-made pulse electrical source and strong magnetic field solidification tester,the effect of strong pulse magnetic field on graphite morphology and solidification structure of gray cast iron was studied.The results show that the structure is remarkably refined after treated by pulse magnetic field,and the width of graphite flakes is decreased while the length is increased after a slight decrease.The solidification temperature and eutectic temperature are increased and the undercooling degree of eutectic transformation is decreased by magnetic field.

  8. Campo elétrico pulsado Pulsed electric field

    Directory of Open Access Journals (Sweden)

    Mirella Lima Binoti

    2012-05-01

    Full Text Available Campos elétricos pulsados de alta intensidade (CEPAI constituem um método não-térmico de conservação para alimentos em substituição à pasteurização tradicional. Em comparação ao processamento térmico, os CEPAI, além de serem eficientes na eliminação de micro-organismos e na inativação de enzimas, também minimizam as perdas de sabor, cor, textura, nutrientes e componentes termolábeis dos alimentos. O objetivo desse trabalho foi levantar dados bibliográficos atuais sobre o tema CEPAI, abordando: definição do processo, instalação experimental, efeito da ruptura dielétrica do alimento, efeito sobre micro-organismo, enzimas e constituintes dos alimentos. Os dados encontrados na literatura apontam o tratamento por CEPAI como alternativa promissora para a conservação de alimentos, podendo ser utilizado como tecnologia única ou como complemento aos processamentos térmicos.Pulsed electric fields of high intensity (HIPEF is a non-thermal food conservation to replace traditional thermal pasteurization. Compared to thermal processing, the HIPEF as well as being effective in removing microorganisms and inactivate enzymes also minimize the loss of flavor, color, texture, nutrients and labile components of food. The aim of this work was to gather bibliographic data current HIPEF on the subject, covering: experimental setup, effects of dielectric breakdown of food, effect on microorganisms, enzymes and constituents of food. The data found in the literature indicate treatment of HIPEF as a promising alternative for food conservation and it could be used as a single technology or in addition to thermal processing.

  9. Pulsed electric field processing of egg products: a review.

    Science.gov (United States)

    Yogesh, K

    2016-02-01

    Thermal processing ensures safety and enhances the shelf-life of most of the food products. It alters the structural-chemical composition, modifies heat labile components, as well as affects the functional properties of food products. This has driven the development of non-thermal food processing techniques, primarily for extending the shelf-life of different food products. These techniques are currently also being evaluated for their effects on product processing, quality and other safety parameters. Pulsed electric field (PEF) is an example of non-thermal technique which can be applied for a variety of purpose in the food processing industry. PEF can be used for antimicrobial treatment of various food products to improve the storability or food safety, for extraction and recovery of some high-value compounds from a food matrix or for stabilization of various food products through inactivation of some enzymes or catalysts. Research on the application of PEF to control spoilage or pathogenic microorganisms in different egg products is being currently focused. It has been reported that PEF effectively reduces the activity of various microorganisms in a variety of egg products. However, the PEF treatment also alters the structural and functional properties to some extent and there is a high degree of variability between different studies. In addition to integrating findings, the present review also provides several explanations for the inconsistency in findings between different studies related to PEF processing of egg products. Several specific recommendations for future research directions on PEF processing are well discussed in this review.

  10. XPCS study of dynamic correlation in polyurethane gel-carbonyl iron composite under magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Grigoriew, Helena [Institute of Nuclear Chemistry and Technology, Warsaw 03195 (Poland); Wiegart, Lutz [ESRF, Grenoble, 38043 Cedex 9 (France); Boczkowska, Anna [Faculty of Materials Science, Warsaw University of Technology (Poland); Mirkowska, Monika, E-mail: haga311@hotmail.co [Institute of Electronic Materials Technology, Warsaw (Poland)

    2010-10-01

    An X-ray photon correlation spectroscopy (XPCS) study of composite-type material consisting of polyurethane gel and carbonyl iron micrometric spheres was performed under magnetic fields of 0, 300 and 600 mT. The onion-like spheres structure was destroyed during the composite processing. The following conclusions were obtained from the study: -The polyurethane matrix is preferred as a source for the observed dynamic effects. -Below 300mT the material dynamics in direction of the outer magnetic field are very clear. -For 600 mT the dependence of the dynamics on magnetic field direction disappears, but the correlation rate is much higher. These findings may be caused by a disturbance of the polymer mesostructure by larger strain leading to its cross-linking.

  11. Transition-Selective Pulses in Zero-Field Nuclear Magnetic Resonance.

    Science.gov (United States)

    Sjolander, Tobias F; Tayler, Michael C D; King, Jonathan P; Budker, Dmitry; Pines, Alexander

    2016-06-30

    We use low-amplitude, ultralow frequency pulses to drive nuclear spin transitions in zero and ultralow magnetic fields. In analogy to high-field NMR, a range of sophisticated experiments becomes available as these allow narrow-band excitation. As a first demonstration, pulses with excitation bandwidths 0.5-5 Hz are used for population redistribution, selective excitation, and coherence filtration. These methods are helpful when interpreting zero- and ultralow-field NMR spectra that contain a large number of transitions.

  12. Comparison of membrane electroporation and protein denature in response to pulsed electric field with different durations.

    Science.gov (United States)

    Huang, Feiran; Fang, Zhihui; Mast, Jason; Chen, Wei

    2013-05-01

    In this paper, we compared the minimum potential differences in the electroporation of membrane lipid bilayers and the denaturation of membrane proteins in response to an intensive pulsed electric field with various pulse durations. Single skeletal muscle fibers were exposed to a pulsed external electric field. The field-induced changes in the membrane integrity (leakage current) and the Na channel currents were monitored to identify the minimum electric field needed to damage the membrane lipid bilayer and the membrane proteins, respectively. We found that in response to a relatively long pulsed electric shock (longer than the membrane intrinsic time constant), a lower membrane potential was needed to electroporate the cell membrane than for denaturing the membrane proteins, while for a short pulse a higher membrane potential was needed. In other words, phospholipid bilayers are more sensitive to the electric field than the membrane proteins for a long pulsed shock, while for a short pulse the proteins become more vulnerable. We can predict that for a short or ultrashort pulsed electric shock, the minimum membrane potential required to start to denature the protein functions in the cell plasma membrane is lower than that which starts to reduce the membrane integrity.

  13. Effects of spectral linewidth of ultrashort pulses on the spa-tiotemporal distribution of diffraction fields

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The spatiotemporal characteristics of electromagnetic pulses with ultrabroad spectral bandwidth in the far field are analyzed by using classical scalar diffraction theory. The effects of the ratio of the frequency width to the central frequency on the diffraction spatial distribution are discussed. It is concluded that the diffraction spatial dis-tribution of the pulsed radiation gets narrower than a mono-chromatic wave when the frequency width of the pulse is comparable to or larger than its central frequency.

  14. Preparation of zirconia nanopowders in ultrasonic field by the sol-gel method

    Energy Technology Data Exchange (ETDEWEB)

    Li Xiaoxi; Chen Ling; Li Bing; Li Lin [Inst. of Light Industry and Chemical Engineering, South China Univ. of Technology, Guangzhou (China)

    2005-07-01

    Zirconia nanopowders were prepared in the ultrasonic field by the sol-gel method and the sonochemical effect on the structure of zirconium hydroxide and the zirconia nanopowder properties were systematically investigated in this work. Ultrasound was introduced into the different stages of the synthesis of zirconia nanopowders in sol-gel reaction system, and zirconium hydroxides and the zirconia nanopowders with different properties were obtained. The results indicated that ultrasonic cavitation could not only disaggregate the agglomerates of zirconia colloidal particles but also reduce the amount of coordinated H{sub 2}O, free H{sub 2}O and free hydroxyl groups of the zirconium hydroxide colloidal particles, thus effectively preventing the formation of hard agglomerates in zirconia powders. Moreover, the effects of different ultrasonic output powers and treatment cycles on the structure and properties of ZrO{sub 2} nanopowders were studied by TEM, XRD and SAXS. Zirconia nanopowders with an extremely small crystallite size (10.3 nm) and a narrow size distribution were yielded with 520 W ultrasound for 6 treatment cycles on the formation period and 600 W ultrasound for 2 treatment cycles on the washing period. It is concluded that the ultrasonic field is a potential method for nanopowder preparation. (orig.)

  15. Study on molecular typing by pulsed-field gel electrophoresis of food Listeria monocytogenes isolates from eight province(municipalities) of China%中国八省市食品来源单核细胞增生李斯特菌的脉冲场凝胶电泳分析

    Institute of Scientific and Technical Information of China (English)

    祝仁发; 宫照龙; 叶长芸; 崔志刚; 金东; 冉陆; 许珂; 王连秀; 陈伟伟

    2007-01-01

    目的 采用国际标准化的脉冲场凝胶电泳(PFGE)分析方法对单核细胞增生李斯特菌(Lm)进行基因分型,初步建立中国Lm的基因分型数据库.方法 按照标准化的Lm-PFGE方法对来自国内8个省市、多种食品来源的118株Lm进行了PFGE分型.结果 118株Lm分成了39种带型,其中GX6A160004型有37株菌,占分析菌株的31.36%,是主要型别.结论 初步建立了中国单核细胞增生李斯特菌用于网络监测分析(PulseNet China)的基础数据库,发现同型菌株在全国多个地区广泛存在.

  16. Electric field measurements in a nanosecond pulse discharge in atmospheric air

    Science.gov (United States)

    Simeni Simeni, Marien; Goldberg, Benjamin M.; Zhang, Cheng; Frederickson, Kraig; Lempert, Walter R.; Adamovich, Igor V.

    2017-05-01

    The paper presents the results of temporally and spatially resolved electric field measurements in a nanosecond pulse discharge in atmospheric air, sustained between a razor edge high-voltage electrode and a plane grounded electrode covered by a thin dielectric plate. The electric field is measured by picosecond four-wave mixing in a collinear phase-matching geometry, with time resolution of approximately 2 ns, using an absolute calibration provided by measurements of a known electrostatic electric field. The results demonstrate electric field offset on the discharge center plane before the discharge pulse due to surface charge accumulation on the dielectric from the weaker, opposite polarity pre-pulse. During the discharge pulse, the electric field follows the applied voltage until ‘forward’ breakdown occurs, after which the field in the plasma is significantly reduced due to charge separation. When the applied voltage is reduced, the field in the plasma reverses direction and increases again, until the weak ‘reverse’ breakdown occurs, producing a secondary transient reduction in the electric field. After the pulse, the field is gradually reduced on a microsecond time scale, likely due to residual surface charge neutralization by transport of opposite polarity charges from the plasma. Spatially resolved electric field measurements show that the discharge develops as a surface ionization wave. Significant surface charge accumulation on the dielectric surface is detected near the end of the discharge pulse. Spatially resolved measurements of electric field vector components demonstrate that the vertical electric field in the surface ionization wave peaks ahead of the horizontal electric field. Behind the wave, the vertical field remains low, near the detection limit, while the horizontal field is gradually reduced to near the detection limit at the discharge center plane. These results are consistent with time-resolved measurements of electric field

  17. Temporal and Spectral Properties of Subcycle THz Pulses in Near-Field Zone

    Institute of Scientific and Technical Information of China (English)

    YANG Yu-Ping; YAN Wei; XU Xin-Long; SHI Yu-Lei; WANG Li

    2005-01-01

    @@ In a novel generation and detection configuration of terahertz (THz) radiation, we investigate experimentally and numerically the properties of sub-cycle THz pulses in the near field. It is found that the sub-cycle THz pulses experience significant spectral and temporal deformation in the near-field zone. The variations of both the pulse waveform and spectral distribution of the THz electric field are clearly observed in our experiments when the spot size of source is changed. Numerical simulations based on Gaussian distribution are performed to explain the details of the data and lead to an excellent agreement with the experimental results.

  18. Electron-Positron Pair Production in Structured Pulses of Electric Fields

    CERN Document Server

    Kohlfürst, Christian

    2012-01-01

    The non-perturbative electron-positron pair production in time-dependent electric fields is investigated. The quantum kinetic formalism is employed in order to calculate the electron density for various field configurations. The corresponding set of first order, ordinary differential equations is analyzed and numerically solved. The focus of this study lies on the dynamically assisted Schwinger effect in pulsed electric fields with at least two different time scales. Furthermore, interference effects arising in setups with multiple pulses are examined and first results for an optimization of the particle number yield by pulse-shaping are given.

  19. Theory of gel electrophoresis in high fields: Evolution of a population of hernias

    Science.gov (United States)

    Long, Didier; Viovy, Jean-Louis

    1997-02-01

    We consider long polyelectrolytes that are initially at rest in a gel and suddenly submitted to a strong electric field. The evolution of the conformation regime is described up to the final disengagement from the initial tube. Just after the field has been applied, the chain adopts a comb-like conformation with several “hernias”, which evolve in competition with each other. As long as the conformation has many hernias, the distribution of their size follows a self-similar law, first described by Deutsch. The number of hernias decreases, and ultimately the chain disengages from its initial tube. Various predictions for the conformation of the chain in this last stage and for time constants are proposed. In particular, the disengagement times are found to follow a self-similar law in the size of the chains.

  20. Transient features in nanosecond pulsed electric fields differentially modulate mitochondria and viability.

    Directory of Open Access Journals (Sweden)

    Stephen J Beebe

    Full Text Available It is hypothesized that high frequency components of nanosecond pulsed electric fields (nsPEFs, determined by transient pulse features, are important for maximizing electric field interactions with intracellular structures. For monopolar square wave pulses, these transient features are determined by the rapid rise and fall of the pulsed electric fields. To determine effects on mitochondria membranes and plasma membranes, N1-S1 hepatocellular carcinoma cells were exposed to single 600 ns pulses with varying electric fields (0-80 kV/cm and short (15 ns or long (150 ns rise and fall times. Plasma membrane effects were evaluated using Fluo-4 to determine calcium influx, the only measurable source of increases in intracellular calcium. Mitochondria membrane effects were evaluated using tetramethylrhodamine ethyl ester (TMRE to determine mitochondria membrane potentials (ΔΨm. Single pulses with short rise and fall times caused electric field-dependent increases in calcium influx, dissipation of ΔΨm and cell death. Pulses with long rise and fall times exhibited electric field-dependent increases in calcium influx, but diminished effects on dissipation of ΔΨm and viability. Results indicate that high frequency components have significant differential impact on mitochondria membranes, which determines cell death, but lesser variances on plasma membranes, which allows calcium influxes, a primary determinant for dissipation of ΔΨm and cell death.

  1. Transient features in nanosecond pulsed electric fields differentially modulate mitochondria and viability.

    Science.gov (United States)

    Beebe, Stephen J; Chen, Yeong-Jer; Sain, Nova M; Schoenbach, Karl H; Xiao, Shu

    2012-01-01

    It is hypothesized that high frequency components of nanosecond pulsed electric fields (nsPEFs), determined by transient pulse features, are important for maximizing electric field interactions with intracellular structures. For monopolar square wave pulses, these transient features are determined by the rapid rise and fall of the pulsed electric fields. To determine effects on mitochondria membranes and plasma membranes, N1-S1 hepatocellular carcinoma cells were exposed to single 600 ns pulses with varying electric fields (0-80 kV/cm) and short (15 ns) or long (150 ns) rise and fall times. Plasma membrane effects were evaluated using Fluo-4 to determine calcium influx, the only measurable source of increases in intracellular calcium. Mitochondria membrane effects were evaluated using tetramethylrhodamine ethyl ester (TMRE) to determine mitochondria membrane potentials (ΔΨm). Single pulses with short rise and fall times caused electric field-dependent increases in calcium influx, dissipation of ΔΨm and cell death. Pulses with long rise and fall times exhibited electric field-dependent increases in calcium influx, but diminished effects on dissipation of ΔΨm and viability. Results indicate that high frequency components have significant differential impact on mitochondria membranes, which determines cell death, but lesser variances on plasma membranes, which allows calcium influxes, a primary determinant for dissipation of ΔΨm and cell death.

  2. Pasteurization of strawberry puree using a pilot plant pulsed electric fields (PEF) system

    Science.gov (United States)

    The processing of strawberry puree by pulsed electric fields (PEF) in a pilot plant system has never been evaluated. In addition, a method does not exist to validate the exact number and shape of the pulses applied during PEF processing. Both buffered peptone water (BPW) and fresh strawberry puree (...

  3. Validation of a pulsed electric field process to pasteurize strawberry puree

    Science.gov (United States)

    An inexpensive data acquisition method was developed to validate the exact number and shape of the pulses applied during pulsed electric fields (PEF) processing. The novel validation method was evaluated in conjunction with developing a pasteurization PEF process for strawberry puree. Both buffered...

  4. Pulsed electromagnetic field radiation from a narrow slot antenna with a dielectric layer

    NARCIS (Netherlands)

    Štumpf, M.; De Hoop, A.T.; Lager, I.E.

    2010-01-01

    Analytic time domain expressions are derived for the pulsed electromagnetic field radiated by a narrow slot antenna with a dielectric layer in a two‐dimensional model configuration. In any finite time window of observation, exact pulse shapes for the propagated, reflected, and refracted wave constit

  5. Anomalous spectral behaviour of diffracted chirped Gaussian pulses in the near field

    Institute of Scientific and Technical Information of China (English)

    Pan Liu-Zhan; L(u) Bai-Da

    2004-01-01

    By using the Fourier transform method, analytical expressions for the axial power spectrum and near-field intensity in the spacetime domain of chirped Gaussian pulses diffracted at an aperture are derived, which permit us to study changes in spectral and temporal profiles of the chirped Gaussian pulses both analytically and numerically. Detailed numerical results and physical analysis show that spectral anomalies take place in the neighbourhood of certain critical distances, and the shifting of maximum and splitting of temporal intensity profiles appear. In particular, for ultrashort chirped pulses, there exists also spectral switch. Besides the truncation parameter, the chirp parameter and pulse duration affect the behaviour of spectral switches.

  6. Generation of elliptically polarized nitrogen-ion laser fields using two-color femtosecond laser pulses

    CERN Document Server

    Li, Ziting; Chu, Wei; Xie, Hongqiang; Yao, Jinping; Li, Guihua; Qiao, Lingling; Wang, Zhanshan; Cheng, Ya

    2015-01-01

    We experimentally investigate generation of molecular nitrogen-ion lasers with two femtosecond laser pulses at different wavelengths. The first pulse serves as the pump which ionizes the nitrogen molecules and excites the molecular ions to excited electronic states. The second pulse serves as the probe which leads to stimulated emission from the excited molecular ions. We observe that changing the angle between the polarization directions of the two pulses gives rise to elliptically polarized molecular nitrogen-ion laser fields, which is interpreted as a result of strong birefringence of the gain medium near the wavelengths of the molecular nitrogen-ion laser.

  7. Strong Field Molecular Ionization in the Impulsive Limit: Freezing Vibrations with Short Pulses

    CERN Document Server

    Sándor, Péter; Zhao, Arthur; Rozgonyi, Tamás; Ruckenbauer, Matthias; Marquetand, Philipp; Weinacht, Thomas

    2016-01-01

    We study strong-field molecular ionization as a function of pulse duration. Experimental measurements of the photoelectron yield for a number of molecules reveal competition between different ionization continua (cationic states) which depends strongly on pulse duration. Surprisingly, in the limit of short pulse duration, we find that a single ionic continuum dominates the yield, whereas multiple continua are produced for longer pulses. Using calculations which take vibrational dynamics into account, we interpret our results in terms of nuclear motion and non-adiabatic dynamics during the ionization process.

  8. Loudness of tone pulses in a free field

    DEFF Research Database (Denmark)

    Poulsen, Torben

    1981-01-01

    ) of about 200 ms near and at the threshold, whereas tau is about 100 ms at levels well above threshold. Discrepancies exist, nevertheless, between this single-time-constant model and the experimental data obtained for the pulses of shortest duration. To account for this, a model is proposed comprising...

  9. In vitro and in vivo invasiveness of different pulsed-field get electrophoresis types of Listeria monocytogenes

    DEFF Research Database (Denmark)

    Larsen, Charlotte Nexmann; Nørrung, Birgit; Sommer, Helle Mølgaard

    2002-01-01

    The virulence of different pulsed-field gel electrophoresis (PFGE) types of Listeria monocytogenes was examined by monitoring their ability to invade Caco-2 cells. Strains belonging to seven different PFGE types originating from both foods and humans were included. No significant differences...... others is supported by this study showing that certain PFGE types of L. monocytogenes commonly found in food are less invasive than others to Caco-2 cells. In contrast to the differences in invasion, identical intracellular growth rates between the different PFGE types were observed. In vivo studies...... of the actual ability of the strains to invade the liver and spleen of cimetidine-treated rats following an oral dose of 109 L. monocytogenes cells were performed for isolates of PFGE types 1, 2, 5, and 15. After 2 days, equal amounts of bacteria were observed in the liver and spleen of the rats for any...

  10. Nuclear forward scattering of synchrotron radiation in pulsed high magnetic fields.

    Science.gov (United States)

    Strohm, C; Van der Linden, P; Rüffer, R

    2010-02-26

    We report the demonstration of nuclear forward scattering of synchrotron radiation from 57Fe in ferromagnetic alpha iron in pulsed high magnetic fields up to 30 T. The observed magnetic hyperfine field follows the calculated high field bulk magnetization within 1%, establishing the technique as a precise tool for the study of magnetic solids in very high magnetic fields. To perform these experiments in pulsed fields, we have developed a detection scheme for fully time resolved nuclear forward scattering applicable to other pump probe experiments.

  11. Angular spectrum approach for fast simulation of pulsed non-linear ultrasound fields

    DEFF Research Database (Denmark)

    Du, Yigang; Jensen, Henrik; Jensen, Jørgen Arendt

    2011-01-01

    The paper presents an Angular Spectrum Approach (ASA) for simulating pulsed non-linear ultrasound fields. The source of the ASA is generated by Field II, which can simulate array transducers of any arbitrary geometry and focusing. The non-linear ultrasound simulation program - Abersim, is used...... the fundamental and keep the second harmonic field, since Abersim simulates non-linear fields with all harmonic components. ASA and Abersim are compared for the pulsed fundamental and second harmonic fields in the time domain at depths of 30 mm, 40 mm (focal depth) and 60 mm. Full widths at -6 dB (FWHM) are f0...

  12. Effect of temperature field on solidification structure of pure Al under pulse magneto-oscillation

    Directory of Open Access Journals (Sweden)

    Li Bo

    2011-05-01

    Full Text Available This article discusses the effect of temperature field on the Pulse Magneto-Oscillation (PMO induced solidification refinement of pure aluminium to provide more information for the industrial application of the PMO solidification technology. The temperature field is altered mainly by applied variable cooling conditions and pulse parameters. Experimental results show that the refinement effect in the case of full sand mould applied is weakened with the decreasing of cooling rate, however, in the alternative case, the sand mould whose sand bottom was replaced by a graphite block is favorable to the survival of equiaxed nucleus. The refinement mechanism is discussed in terms of the relationship between temperature field and the formation process of solidified structure. The formation or survival of nucleus depends on both temperature field and Joule heat produced by PMO, both low pulse frequency and high pulse current were experimentally confirmed to be effective; and PMO was demonstrated high potential in industrial application.

  13. Orientationally invariant metrics of apparent compartment eccentricity from double pulsed field gradient diffusion experiments

    DEFF Research Database (Denmark)

    Jespersen, Sune Nørhøj; Lundell, Henrik; Sønderby, Casper Kaae

    2013-01-01

    Pulsed field gradient diffusion sequences (PFG) with multiple diffusion encoding blocks have been indicated to offer new microstructural tissue information, such as the ability to detect nonspherical compartment shapes in macroscopically isotropic samples, i.e. samples with negligible directional...

  14. Heat diffusion characteristics of magnetite nanoparticles dispersed hydro-gel in alternating magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Suto, Makoto [Graduate School of Environmental Studies, Tohoku University, Sendai (Japan); Kosukegawa, Hiroyuki; Maruta, Kaoru; Ohta, Makoto [Institute of Fluid Science, Tohoku University, Sendai (Japan); Tohji, Kazuyuki [Graduate School of Environmental Studies, Tohoku University, Sendai (Japan); Jeyadevan, Balachandran [Graduate School of Environmental Studies, Tohoku University, Sendai (Japan)], E-mail: jeya@mail.kankyo.tohoku.ac.jp

    2009-10-15

    Heat diffusion characteristics of a spherical heat source dispersing magnetite nanoparticles (MNPs) in hydro-gel were investigated numerically and experimentally to evaluate the conditions required for magnetic fluid hyperthermia (MFH). Numerical estimation assumed one-dimensional spherical model and constant heat evolution. Experimental observation was carried out by exposing the magnetite-dispersed hydro-gel in an AC magnetic field with strength and frequency of 3.2 kA/m and 600 kHz, respectively. The temperature distribution observed along the radial axis of the spherical heat source agreed well with the theoretical estimation quantitatively and qualitatively. However, the minor difference existed between the theory and experiment was due to the variation in experimentally determined and actual particle size distributions. Thus, we could conclude that the proposed algorithm could be extended to be used in the estimation of the temperature distribution in intravital conditions with blood flow, metabolism etc., to arrive at biologically significant conclusions helpful for MFH cancer treatment.

  15. Effect of temperature field on solidification structure of pure Al under pulse magneto-oscillation

    OpenAIRE

    Li Bo; Yin Zhenxing; Gong Yongyong

    2011-01-01

    This article discusses the effect of temperature field on the Pulse Magneto-Oscillation (PMO) induced solidification refinement of pure aluminium to provide more information for the industrial application of the PMO solidification technology. The temperature field is altered mainly by applied variable cooling conditions and pulse parameters. Experimental results show that the refinement effect in the case of full sand mould applied is weakened with the decreasing of cooling rate, however, in ...

  16. Experimental studies of axial magnetic fields generated in ultrashort-pulse laser-plasma interaction

    Institute of Scientific and Technical Information of China (English)

    李玉同; 张杰; 陈黎明; 赵理曾; 夏江帆; 魏志义; 江文勉

    2000-01-01

    The quasistatic axial magnetic fields in plasmas produced by ultrashort laser pulses were measured by measuring the Faraday rotation angle of the backscattered emission. The spatial distribution of the axial magnetic field was obtained with a peak value as high as 170 Tesla. Theory suggests that the axial magnetic field is generated by dynamo effect in laser-plasma interaction.

  17. Metamagnetic transitions of DyAg in pulsed high magnetic field

    Science.gov (United States)

    Yamagishi, A.; Yonenobu, K.; Kondo, O.; Morin, P.; Date, M.

    1990-12-01

    Metamagnetic transitions of a single crystal DyAg are investigated by using pulsed magnetic fields up to 410 kOe. Four step-magnetizations are found with the field along the [111] direction. These transitions are well understood by introducing a new model that the quadrupole order is quenched under high magnetic field.

  18. Metamagnetic transitions of DyAg in pulsed high magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Yamagishi, A.; Yonenobu, K.; Kondo, O.; Date, M. (Research Center for Extreme Materials, Osaka Univ. (Japan)); Morin, P. (Lab. Louis Neel, CNRS, 38 - Grenoble (France))

    1990-12-01

    Metamagnetic transitions of a single crystal DyAg are investigated by using pulsed magnetic fields up to 410 kOe. Four step-magnetizations are found with the field along the (111) direction. These transitions are well understood by introducing a new model that the quadrupole order is quenched under high magnetic field. (orig.).

  19. Permeabilization of plant tissues by monopolar pulsed electric fields: effect of frequency.

    Science.gov (United States)

    Asavasanti, Suvaluk; Ristenpart, William; Stroeve, Pieter; Barrett, Diane M

    2011-01-01

    Pulsed electric fields (PEF) nonthermally induce cell membrane permeabilization and thereby improve dehydration and extraction efficiencies in food plant materials. Effects of electrical field strength and number of pulses on plant tissue integrity have been studied extensively. Two previous studies on the effect of pulse frequency, however, did not provide a clear view: one study suggested no effect of frequency, while the other found a greater impact on tissue integrity at lower frequency. This study establishes the effect of pulse frequency on integrity of onion tissues. Changes in electrical characteristics, ion leakage, texture parameters, and percent weight loss were quantified for a wide range of pulse frequencies under conditions of fixed field strength and pulse number. Optical microscopy and viable-cell staining provided direct visualization of effects on individual cells. The key finding is that lower frequencies (f plant tissue. We hypothesize that cytoplasmic streaming plays a significant role in moving conductive ionic species from permeabilized cells to the intercellular space between plant cells, making subsequent pulses more efficacious at sufficiently low frequencies. The results suggest that decreasing the pulse frequency in PEF may minimize the number of pulses needed to achieve a desired amount of permeabilization, thus lowering the total energy consumption. Practical Application: PEF cause pores to be formed in plant cell membranes, thereby improve moisture removal and potential extraction of desirable components. This study used in situ microscopic evaluation of onion cells, as they were pulsed with electric fields at different frequencies, to determine whether frequency was an important parameter. We illustrate that membranes were more effectively broken at lower frequencies as compared to higher frequencies. Application of this information will allow for improved design of PEF systems for more energy efficient dehydration or extraction of

  20. Assessment of the electrochemical effects of pulsed electric fields in a biological cell suspension.

    Science.gov (United States)

    Chafai, Djamel Eddine; Mehle, Andraž; Tilmatine, Amar; Maouche, Bachir; Miklavčič, Damijan

    2015-12-01

    Electroporation of cells is successfully used in biology, biotechnology and medicine. Practical problems still arise in the electroporation of cells in suspension. For example, the determination of cell electroporation is still a demanding and time-consuming task. Electric pulses also cause contamination of the solution by the metal released from the electrodes and create local enhancements of the electric field, leading to the occurrence of electrochemical reactions at the electrode/electrolyte interface. In our study, we investigated the possibility of assessing modifications to the cell environment caused by pulsed electric fields using electrochemical impedance spectroscopy. We designed an experimental protocol to elucidate the mechanism by which a pulsed electric field affects the electrode state in relation to different electrolyte conductivities at the interface. The results show that a pulsed electric field affects electrodes and its degree depends on the electrolyte conductivity. Evolution of the electrochemical reaction rate depends on the initial free charges and those generated by the pulsed electric field. In the presence of biological cells, the initial free charges in the medium are reduced. The electrical current path at low frequency is longer, i.e., conductivity is decreased, even in the presence of increased permeability of the cell membrane created by the pulsed electric field.

  1. [Negative air ions generated by plants upon pulsed electric field stimulation applied to soil].

    Science.gov (United States)

    Wu, Ren-ye; Deng, Chuan-yuan; Yang, Zhi-jian; Weng, Hai-yong; Zhu, Tie-jun-rong; Zheng, Jin-gui

    2015-02-01

    This paper investigated the capacity of plants (Schlumbergera truncata, Aloe vera var. chinensis, Chlorophytum comosum, Schlumbergera bridgesii, Gymnocalycium mihanovichii var. friedrichii, Aspidistra elatior, Cymbidium kanran, Echinocactus grusonii, Agave americana var. marginata, Asparagus setaceus) to generate negative air ions (NAI) under pulsed electric field stimulation. The results showed that single plant generated low amounts of NAI in natural condition. The capacity of C. comosum and G. mihanovichii var. friedrichii generated most NAI among the above ten species, with a daily average of 43 ion · cm(-3). The least one was A. americana var. marginata with the value of 19 ion · cm(-3). When proper pulsed electric field stimulation was applied to soil, the NAI of ten plant species were greatly improved. The effect of pulsed electric field u3 (average voltage over the pulse period was 2.0 x 10(4) V, pulse frequency was 1 Hz, and pulse duration was 50 ms) was the greatest. The mean NAI concentration of C. kanran was the highest 1454967 ion · cm(-3), which was 48498.9 times as much as that in natural condition. The lowest one was S. truncata with the value of 34567 ion · cm(-3), which was 843.1 times as much as that in natural condition. The capacity of the same plants to generate negative air ion varied extremely under different intensity pulsed electric fields.

  2. Treatment of nail psoriasis with Pulse Dye Laser plus calcipotriol betametasona gel vs. Nd:YAG plus calcipotriol betamethasone gel: An intrapatient left-to-right controlled study.

    Science.gov (United States)

    Arango-Duque, L C; Roncero-Riesco, M; Usero Bárcena, T; Palacios Álvarez, I; Fernández López, E

    2017-03-01

    Treatment of nail psoriasis remains a challenging and often disappointing situation. To compare the efficacy, adverse reactions and tolerability of treatment of nail psoriasis with PDL vs. Nd:YAG, in association with betametasona calcipotriol gel. An open, prospective intrapatient left-to-right study was designed. The right hand of each patient received treatment with PDL and the left hand with Nd:YAG. Betamethasone calcipotriol gel was applied once a day during the first week after each laser session. A total of four sessions were administered. The clinical efficacy was evaluated according to the NAPSI score. All patients showed improvement in nail bed and nail matrix psoriasis. The global NAPSI mean declined in 15.46 (p<0.000). There was neither statistical difference between the reduction in nail bed and matrix NAPSI nor in the treatment with PDL vs. Nd:YAG. The administration of Nd:YAG was more painful. No serious adverse effects were documented. No random assignment and the small number of patients. PDL and Nd:YAG have proven to be an effective treatment for nail psoriasis with no serious adverse effect. No statistically significant difference was found between the two treatments. Copyright © 2016. Publicado por Elsevier España, S.L.U.

  3. Analytical solution for the diffusion of a capacitor discharge generated magnetic field pulse in a conductor

    Directory of Open Access Journals (Sweden)

    Ilmārs Grants

    2016-06-01

    Full Text Available Powerful forces arise when a pulse of a magnetic field in the order of a few tesla diffuses into a conductor. Such pulses are used in electromagnetic forming, impact welding of dissimilar materials and grain refinement of solidifying alloys. Strong magnetic field pulses are generated by the discharge current of a capacitor bank. We consider analytically the penetration of such pulse into a conducting half-space. Besides the exact solution we obtain two simple self-similar approximate solutions for two sequential stages of the initial transient. Furthermore, a general solution is provided for the external field given as a power series of time. Each term of this solution represents a self-similar function for which we obtain an explicit expression. The validity range of various approximate analytical solutions is evaluated by comparison to the exact solution.

  4. Analytical solution for the diffusion of a capacitor discharge generated magnetic field pulse in a conductor

    Science.gov (United States)

    Grants, Ilmārs; Bojarevičs, Andris; Gerbeth, Gunter

    2016-06-01

    Powerful forces arise when a pulse of a magnetic field in the order of a few tesla diffuses into a conductor. Such pulses are used in electromagnetic forming, impact welding of dissimilar materials and grain refinement of solidifying alloys. Strong magnetic field pulses are generated by the discharge current of a capacitor bank. We consider analytically the penetration of such pulse into a conducting half-space. Besides the exact solution we obtain two simple self-similar approximate solutions for two sequential stages of the initial transient. Furthermore, a general solution is provided for the external field given as a power series of time. Each term of this solution represents a self-similar function for which we obtain an explicit expression. The validity range of various approximate analytical solutions is evaluated by comparison to the exact solution.

  5. Single-shot spatiotemporal measurements of high-field terahertz pulses

    Energy Technology Data Exchange (ETDEWEB)

    van Tilborg, Jeroen; Schroeder, Carl; Toth, Csaba; Geddes, Cameron; Esarey, Eric; Leemans, Wim

    2011-06-17

    The electric field profiles of broad-bandwidth coherent terahertz (THz) pulses, emitted by laser-wakefield-accelerated electron bunches, are studied. The near-single-cycle THz pulses are measured with two single-shot techniques in the temporal and spatial domains. Spectra of 0-6 THz and peak fields up to {approx_equal} 0.4 MV cm{sup -1} are observed. The measured field substructure demonstrates the manifestation of spatiotemporal coupling at focus, which affects the interpretation of THz radiation as a bunch diagnostic and in high-field pump-probe experiments.

  6. Tomographic reconstruction of transient acoustic fields recorded by pulsed TV holography.

    Science.gov (United States)

    Gren, P; Schedin, S; Li, X

    1998-02-10

    Pulsed TV holography combined with computerized tomography (CT) are used to evaluate the three-dimensional distribution of transient acoustic fields in air. Experiments are performed with an electrical discharge between two electrodes as the sound source. Holograms from several directions of the acoustic field are recorded directly onto a CCD detector by use of a double-pulsed ruby laser as the light source. Phase maps, representing projections of the acoustic field, are evaluated quantitatively from the recorded holograms. The projections are used for the CT reconstruction to evaluate the pressure-field distribution in any cross section of the measured volume of air.

  7. Improving the accuracy of pulsed field gradient NMR diffusion experiments: Correction for gradient non-uniformity

    Science.gov (United States)

    Connell, Mark A.; Bowyer, Paul J.; Adam Bone, P.; Davis, Adrian L.; Swanson, Alistair G.; Nilsson, Mathias; Morris, Gareth A.

    2009-05-01

    Pulsed field gradient NMR is a well-established technique for the determination of self-diffusion coefficients. However, a significant source of systematic error exists in the spatial variation of the applied pulsed field gradient. Non-uniform pulsed field gradients cause the decay of peak amplitudes to deviate from the expected exponential dependence on gradient squared. This has two undesirable effects: the apparent diffusion coefficient will deviate from the true value to an extent determined by the choice of experimental parameters, and the error estimated by the nonlinear least squares fitting will contain a significant systematic contribution. In particular, the apparent diffusion coefficient determined by exponential fitting of the diffusional attenuation of NMR signals will depend both on the exact pulse widths used and on the range of gradient amplitudes chosen. These problems can be partially compensated for if experimental attenuation data are fitted to a function corrected for the measured spatial dependence of the gradient and signal strength. This study describes a general alternative to existing methods for the calibration of NMR diffusion measurements. The dominant longitudinal variation of the pulsed field gradient amplitude and the signal strength are mapped by measuring pulsed field gradient echoes in the presence of a weak read gradient. These data are then used to construct a predicted signal decay function for the whole sample, which is parameterised as the exponential of a power series. Results are presented which compare diffusion coefficients obtained using the new calibration method with previous literature values.

  8. Metal release in a stainless steel Pulsed Electric Field (PEF) system Part I. Effect of different pulse shapes; theory and experimental method

    NARCIS (Netherlands)

    Roodenburg, B.; Morren, J.; Berg, H.E.; Haan, S.W.H.de

    2005-01-01

    Liquid pumpable food is mostly pasteurised by heat treatment. In the last decennia there is an increasing interest in so-called Pulsed Electric Field (PEF) treatment. During this treatment food is pumped between two metal electrodes and exposed to short high electric field pulses, typical 2-4 kV mm-

  9. Pulsed field probe of real time magnetization dynamics in magnetic nanoparticle systems

    Science.gov (United States)

    Foulkes, T.; Syed, M.; Taplin, T.

    2015-05-01

    Magnetic nanoparticles (MNPs) are extensively used in biotechnology. These applications rely on magnetic properties that are a keen function of MNP size, distribution, and shape. Various magneto-optical techniques, including Faraday Rotation (FR), Cotton-Mouton Effect, etc., have been employed to characterize magnetic properties of MNPs. Generally, these measurements employ AC or DC fields. In this work, we describe the results from a FR setup that uses pulsed magnetic fields and an analysis technique that makes use of the entire pulse shape to investigate size distribution and shape anisotropy. The setup employs a light source, polarizing components, and a detector that are used to measure the rotation of light from a sample that is subjected to a pulsed magnetic field. This magnetic field "snapshot" is recorded alongside the intensity pulse of the sample's response. This side by side comparison yields useful information about the real time magnetization dynamics of the system being probed. The setup is highly flexible with variable control of pulse length and peak magnitude. Examining the raw data for the response of bare Fe3O4 and hybrid Au and Fe3O4 nanorods reveals interesting information about Brownian relaxation and the hydrodynamic size of these nanorods. This analysis exploits the self-referencing nature of this measurement to highlight the impact of an applied field on creating a field induced transparency for a longitudinal measurement. Possible sources for this behavior include shape anisotropy and field assisted aggregate formation.

  10. Study on technology of high-frequency pulsed magnetic field strength measurement.

    Science.gov (United States)

    Chen, Yi-Mei; Liu, Zhi-Peng; Yin, Tao

    2012-01-01

    High-frequency transient weak magnetic field is always involved in researches about biomedical engineering field while common magnetic-field sensors cannot work properly at frequencies as high as MHz. To measure the value of MHz-level weak pulsed magnetic-field strength accurately, this paper designs a measurement and calibration method for pulsed magnetic-field. In this paper, a device made of Nonferromagnetic material was independently designed and applied to pulsed magnetic field measurement. It held an accurately relative position between the magnetic field generating coil and the detecting coil. By applying a sinusoidal pulse to the generator, collecting the induced electromotive force of the detector, the final magnetic field strength was worked out through algorithms written in Matlab according to Faraday's Law. Experiments were carried out for measurement and calibration. Experiments showed that, under good stability and consistency, accurate measurement of magnetic-field strength of a sinepulse magnetic-field can be achieved, with frequency at 0.5, 1, 1.5 MHz and strength level at micro-Tesla. Calibration results carried out a measuring relative error about 2.5%.

  11. Electric field induced needle-pulsed arc discharge carbon nanotube production apparatus: circuitry and mechanical design.

    Science.gov (United States)

    Kia, Kaveh Kazemi; Bonabi, Fahimeh

    2012-12-01

    A simple and low cost apparatus is reported to produce multiwall carbon nanotubes and carbon nano-onions by a low power short pulsed arc discharge reactor. The electric circuitry and the mechanical design details and a micro-filtering assembly are described. The pulsed-plasma is generated and applied between two graphite electrodes. The pulse width is 0.3 μs. A strong dc electric field is established along side the electrodes. The repetitive discharges occur in less than 1 mm distance between a sharp tip graphite rod as anode, and a tubular graphite as cathode. A hydrocarbon vapor, as carbon source, is introduced through the graphite nozzle in the cathode assembly. The pressure of the chamber is controlled by a vacuum pump. A magnetic field, perpendicular to the plasma path, is provided. The results show that the synergetic use of a pulsed-current and a dc power supply enables us to synthesize carbon nanoparticles with short pulsed plasma. The simplicity and inexpensiveness of this plan is noticeable. Pulsed nature of plasma provides some extra degrees of freedom that make the production more controllable. Effects of some design parameters such as electric field, pulse frequency, and cathode shape are discussed. The products are examined using scanning probe microscopy techniques.

  12. Electric field induced needle-pulsed arc discharge carbon nanotube production apparatus: Circuitry and mechanical design

    Science.gov (United States)

    Kia, Kaveh Kazemi; Bonabi, Fahimeh

    2012-12-01

    A simple and low cost apparatus is reported to produce multiwall carbon nanotubes and carbon nano-onions by a low power short pulsed arc discharge reactor. The electric circuitry and the mechanical design details and a micro-filtering assembly are described. The pulsed-plasma is generated and applied between two graphite electrodes. The pulse width is 0.3 μs. A strong dc electric field is established along side the electrodes. The repetitive discharges occur in less than 1 mm distance between a sharp tip graphite rod as anode, and a tubular graphite as cathode. A hydrocarbon vapor, as carbon source, is introduced through the graphite nozzle in the cathode assembly. The pressure of the chamber is controlled by a vacuum pump. A magnetic field, perpendicular to the plasma path, is provided. The results show that the synergetic use of a pulsed-current and a dc power supply enables us to synthesize carbon nanoparticles with short pulsed plasma. The simplicity and inexpensiveness of this plan is noticeable. Pulsed nature of plasma provides some extra degrees of freedom that make the production more controllable. Effects of some design parameters such as electric field, pulse frequency, and cathode shape are discussed. The products are examined using scanning probe microscopy techniques.

  13. Eradication of multidrug-resistant pseudomonas biofilm with pulsed electric fields.

    Science.gov (United States)

    Khan, Saiqa I; Blumrosen, Gaddi; Vecchio, Daniela; Golberg, Alexander; McCormack, Michael C; Yarmush, Martin L; Hamblin, Michael R; Austen, William G

    2016-03-01

    Biofilm formation is a significant problem, accounting for over eighty percent of microbial infections in the body. Biofilm eradication is problematic due to increased resistance to antibiotics and antimicrobials as compared to planktonic cells. The purpose of this study was to investigate the effect of Pulsed Electric Fields (PEF) on biofilm-infected mesh. Prolene mesh was infected with bioluminescent Pseudomonas aeruginosa and treated with PEF using a concentric electrode system to derive, in a single experiment, the critical electric field strength needed to kill bacteria. The effect of the electric field strength and the number of pulses (with a fixed pulse length duration and frequency) on bacterial eradication was investigated. For all experiments, biofilm formation and disruption were confirmed with bioluminescent imaging and Scanning Electron Microscopy (SEM). Computation and statistical methods were used to analyze treatment efficiency and to compare it to existing theoretical models. In all experiments 1500 V are applied through a central electrode, with pulse duration of 50 μs, and pulse delivery frequency of 2 Hz. We found that the critical electric field strength (Ecr) needed to eradicate 100-80% of bacteria in the treated area was 121 ± 14 V/mm when 300 pulses were applied, and 235 ± 6.1 V/mm when 150 pulses were applied. The area at which 100-80% of bacteria were eradicated was 50.5 ± 9.9 mm(2) for 300 pulses, and 13.4 ± 0.65 mm(2) for 150 pulses. 80% threshold eradication was not achieved with 100 pulses. The results indicate that increased efficacy of treatment is due to increased number of pulses delivered. In addition, we that showed the bacterial death rate as a function of the electrical field follows the statistical Weibull model for 150 and 300 pulses. We hypothesize that in the clinical setting, combining systemic antibacterial therapy with PEF will yield a synergistic effect leading to improved

  14. Effects of Pulsed Current and Pulsed Magnetic Field Complex Pretreatment on Martensite Transformation of Cr5 Steel during Continuous Cooling

    Institute of Scientific and Technical Information of China (English)

    Qing-chun LI; Li-juan LI; Guo-wei CHANG; Qi-jie ZHAI

    2015-01-01

    Carbide precipitation and martensite transformation in Cr5 steel have been observed in situ by high-temper-ature confocal laser-scanning microscopy.In this way,the influences of pulsed current and pulsed magnetic field complex pretreatment on carbide precipitation and martensite transformation during continuous cooling have been studied.The results show that the electropulsing complex pretreatment promotes the precipitation of M7 C3-type car-bides at high temperature,increases the start and finish temperatures of martensite transformation,and extends the phase transformation time.Martensite prefers to nucleate in the austenite with less precipitation of carbides due to the chemically homogeneous distribution of solute atoms.

  15. Finite pulse effects on $e^{+}e^{-}$ pair creation from strong electric fields

    CERN Document Server

    Taya, Hidetoshi; Itakura, Kazunori

    2014-01-01

    We investigate electron-positron pair creation from the vacuum in a pulsed electric background field. Employing the Sauter-type pulsed field $E(t) = E_0 {\\rm sech}^2(t/\\tau)$ with height $E_0$ and width $\\tau$, we demonstrate explicitly the interplay between the non-perturbative and perturbative aspects of the pair creation in the background field. In the constant field limit (the long pulse limit), Schwinger's non-perturbative formula is reproduced, while in the short pulse limit the leading-order perturbative treatment is justified. We show that two dimensionless parameters $eE_0 \\tau^2$ and $eE_0 \\tau /m_e$ characterize the importance of multiple interactions with the fields and the transition from the perturbative to the non-perturbative regime. We also reveal that pair creation is enhanced compared to Schwinger's formula when the field strength is relativity weak $|eE_0|/m_e^2 \\lesssim 1$ and the pulse duration is relatively short $m\\tau \\lesssim 1$ and that the enhancement is predominantly described by ...

  16. Investigation on stresses of superconductors under pulsed magnetic fields based on multiphysics model

    Science.gov (United States)

    Yang, Xiaobin; Li, Xiuhong; He, Yafeng; Wang, Xiaojun; Xu, Bo

    2017-04-01

    A multiphysics model for the numerical computation of stresses, trapped field and temperature distribution of a infinite long superconducting cylinder is proposed, based on which the stresses, including the thermal stresses and mechanical stresses due to Lorentz force, and trapped fields in the superconductor subjected to pulsed magnetic fields are analyzed. By comparing the results under pulsed magnetic fields with different pulse durations, it is found that the both the mechanical stress due to the electromagnetic force and the thermal stress due to temperature gradient contribute to the total stress level in the superconductor. For pulsed magnetic field with short durations, the thermal stress is the dominant contribution to the total stress, because the heat generated by AC-loss builds up significant temperature gradient in such short durations. However, for a pulsed field with a long duration the gradient of temperature and flux, as well as the maximal tensile stress, are much smaller. And the results of this paper is meaningful for the design and manufacture of superconducting permanent magnets.

  17. Tumour Cell Membrane Poration and Ablation by Pulsed Low-Intensity Electric Field with Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Lijun Wang

    2015-03-01

    Full Text Available Electroporation is a physical method to increase permeabilization of cell membrane by electrical pulses. Carbon nanotubes (CNTs can potentially act like “lighting rods” or exhibit direct physical force on cell membrane under alternating electromagnetic fields thus reducing the required field strength. A cell poration/ablation system was built for exploring these effects of CNTs in which two-electrode sets were constructed and two perpendicular electric fields could be generated sequentially. By applying this system to breast cancer cells in the presence of multi-walled CNTs (MWCNTs, the effective pulse amplitude was reduced to 50 V/cm (main field/15 V/cm (alignment field at the optimized pulse frequency (5 Hz of 500 pulses. Under these conditions instant cell membrane permeabilization was increased to 38.62%, 2.77-fold higher than that without CNTs. Moreover, we also observed irreversible electroporation occurred under these conditions, such that only 39.23% of the cells were viable 24 h post treatment, in contrast to 87.01% cell viability without presence of CNTs. These results indicate that CNT-enhanced electroporation has the potential for tumour cell ablation by significantly lower electric fields than that in conventional electroporation therapy thus avoiding potential risks associated with the use of high intensity electric pulses.

  18. Generation of an isolated sub-30 attosecond pulse in a two-color laser field and a static electric field

    Institute of Scientific and Technical Information of China (English)

    Zhang Gang-Tai; Bai Ting-Ting; Zhang Mei-Guang

    2012-01-01

    We theoretically investigate high-order harmonic generation(HHG)from a helium ion model in a two-color laser field,which is synthesized by a fundamental pulse and its second harmonic pulse.It is shown that a supercontinuum spectrum can be generated in the two-color field.However,the spectral intensity is very low,limiting the application of the generated attosecond(as)pulse.By adding a static electric field to the synthesized two-color field,not only is the ionization yield of electrons contributing to the harmonic emission remarkably increased,but also the quantum paths of the HHG can be significantly modulated.As a result,the extension and enhancement of the supercontinuum spectrum are achieved,producing an intense isolated 26-as pulse with a bandwidth of about 170.5 eV.In particular,we also analyse the influence of the laser parameters on the ultrabroad supercontinuum spectrum and isolated sub-30-as pulse generation.

  19. Enhanced field-dependent conductivity of magnetorheological gels with low-doped carbon nanotubes

    Science.gov (United States)

    Qu, Hang; Yu, Miao; Fu, Jie; Yang, Pingan; Liu, Yuxuan

    2017-10-01

    Magnetorheological gels (MRG) exhibit field-dependent conductivity and controllable mechanical properties. In order to extend their application field, filling a large number of traditional conductive materials is the most common means to enhance the poor conductivity of MRG. In this study, the conductivity of MRG is improved by low-doped carbon nanotubes (CNTs). The influence of CNTs on the magnetoresistance of MRG is discussed from two aspects—the improvement in electrical conductivity and the magnetic sensitivity of conductivity variation. The percolation threshold of CNTs in MRG should be between 1 wt% and 2 wt%. The conductivity of a 4 wt% CNT-doped sample increases more than 28 000 times compared with pure MRG. However, there is a cliff-like drop for the range and rate of conductivity variation when the doping amount of CNTs is between 3 wt% and 4 wt%. Therefore, it is concluded that the optimal mass fraction of CNTs is 3%, which can maintain a suitable variation range and a strong conductivity. Compared with pure MRG, its conductivity increases by at least two orders of magnitude. Finally, a sketch of particle motion simulation is developed to understand the improving mechanism and the effect of CNTs.

  20. Pulsed electric field technology: Modeling of electric field and temperature distributions within continuous flow PEF treatment chamber

    OpenAIRE

    Salengke, dkk

    2012-01-01

    Innovations and technology developments in the field of food pasteurization and sterilization are continuously evolving. These include innovations in thermal processing technologies such as aseptic processing, ohmic technology, and microwave technology, as well as non-thermal processing technologies which include pulsed electric field technology and high pressure processing technology. This paper discussed the results of a study on mathematical modeling of electric field and temperature distr...

  1. Switching field dependence on heating pulse duration in thermally assisted magnetic random access memories

    Energy Technology Data Exchange (ETDEWEB)

    Papusoi, C. [Spintec, URA 2512 CEA/CNRS, 17 rue des Martyrs, 38054 Grenoble (France)], E-mail: cristian_papusoi@yahoo.com; Conraux, Y.; Prejbeanu, I.L. [Crocus Technology, 5 Robert Schumann, BP 1510, 38025 Grenoble (France); Sousa, R.; Dieny, B. [Spintec, URA 2512 CEA/CNRS, 17 rue des Martyrs, 38054 Grenoble (France)

    2009-08-15

    The minimum applied field H{sub SW} required to reverse the magnetic moment of the ferromagnetic/antiferromagnetic storage layer of a thermally assisted magnetic random access memory (TA-MRAM) device during the application of a heating electric pulse is investigated as a function of pulse power P{sub HP} and duration {delta}. For the same power of the heating pulse P{sub HP} (or, equivalently, for the same temperature of the storage layer), H{sub SW} increases with decreasing heating time {delta}. This behavior is consistently interpreted by a thermally activated propagating domain-wall switching model, corroborated by a real-time study of switching. The increase of H{sub SW} with decreasing pulse width introduces a constraint for the minimum power consumption of a TA-MRAM where writing combines heating and magnetic field application.

  2. Comparison of Pseudomonas aeruginosa isolates from mink by serotyping and pulsed-field gel electrophoresis

    DEFF Research Database (Denmark)

    Hammer, Anne Sofie; Pedersen, Karl; Andersen, Thomas Holmen

    2003-01-01

    aeruginosa of specific PFGE types were found to cause clusters of outbreaks on several farms within a few weeks of each other. However, PFGE types of strains causing clusters of farm outbreaks changed from year to year. These results suggest that some outbreaks of haemorrhagic pneumonia are caused...... by pathogenic strains of R aeruginosa spread between farms and animals either mechanically, or through feed or water from a common source, rather than by random nosocomial infections with strains from the farm environment....

  3. Genetic heterogeneity of Campylobacter concisus determined by pulsed field gel electrophoresis-based macrorestriction profiling

    DEFF Research Database (Denmark)

    Matsheka, M.I.; Elisha, B.G.; Lastovica, A.L.

    2002-01-01

    In order to investigate the genetic diversity of Campylobacter concisus to assist molecular typing studies, the use of macrorestriction profiling was examined. A suitable protocol was developed that included the use of formaldehyde pretreatment to prevent DNA degradation, and restriction enzyme N...

  4. Molecular typing of nosocomial enterococci by pulsed-field gel electrophoresis

    Directory of Open Access Journals (Sweden)

    Dilek Güldemir

    2015-04-01

    nosocomial infections in Dicle University Hospital between November 2010 and June 2012. Our data revealed that more effective infection control programs should be implemented to prevent cross-transmission.[¤

  5. Effects of High-voltage Pulse Electric Field Treatment on the Structure Stability of Konjac Glucomannan

    Institute of Scientific and Technical Information of China (English)

    YAO Min-Na; FAN Lin-Lin; LIU Ya-Nan; CHEN Qing-Ai; ZENG Yuan; JIAN Wen-Jie; PANG Jie

    2011-01-01

    Structures of KGM treated in two high-voltage pulse electric fields were characterized by infrared spectroscopy,Raman spectroscopy,X-ray diffraction and so on.The results showed that intermolecular hydrogen bonding interactions of KGM were reduced after being treated with high-voltage pulse electric field,but there was no significant effect on its fiber chain form and thermal characteristics.Results of the study can provide a useful reference for further study on the structure and property of KGM,and especially can provide theoretical basis for the effect of physical field on the foodstuff deep processing related to KGM.

  6. Modulated heat pulse propagation and partial transport barriers in chaotic magnetic fields

    CERN Document Server

    del-Castillo-Negrete, D

    2016-01-01

    Direct numerical simulations of the time dependent parallel heat transport equation modeling heat pulses driven by power modulation in 3-dimensional chaotic magnetic fields are presented. The numerical method is based on the Fourier formulation of a Lagrangian-Green's function method that provides an accurate and efficient technique for the solution of the parallel heat transport equation in the presence of harmonic power modulation. The numerical results presented provide conclusive evidence that even in the absence of magnetic flux surfaces, chaotic magnetic field configurations with intermediate levels of stochasticity exhibit transport barriers to modulated heat pulse propagation. In particular, high-order islands and remnants of destroyed flux surfaces (Cantori) act as partial barriers that slow down or even stop the propagation of heat waves at places where the magnetic field connection length exhibits a strong gradient. Results on modulated heat pulse propagation in fully stochastic fields and across m...

  7. 25 Tesla pulsed-high-magnetic-field system for soft X-ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, M., E-mail: mhaya@imr.tohoku.ac.jp [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Narumi, Y.; Nojiri, H. [Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Nakamura, T.; Hirono, T.; Kinoshita, T. [JASRI/SPring-8, Sayo, Hyogo 679-5198 (Japan); Kodama, K. [Department of Mechanical Engineering, Nara National College of Technology, Nara 639-1080 (Japan); Kindo, K. [Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581 (Japan)

    2011-04-15

    Research highlights: {yields} We have developed a 25 T pulsed magnetic field system for soft X-ray MCD. {yields} The new capacitor bank can generate a field in the bipolar mode. {yields} We measured the Soft X-ray MCD of paramagnetic Gd{sub 2}O{sub 3} up to 25 T. - Abstract: We have developed a 25 T pulsed high magnetic field system for soft X-ray Magnetic Circular Dichroism: XMCD. The ultra-high vacuum chamber with a pulse magnet coil is installed. By using a newly developed bipolar capacitor bank, the XMCD of paramagnetic Gd{sub 2}O{sub 3} at the M{sub 5} and the M{sub 4} edges was clearly observed at low temperatures. The present system is capable of measuring XMCD of field induced moments in various compounds including paramagnets and antiferromagnets.

  8. Sub-10 nm near-field localization by plasmonic metal nanoaperture arrays with ultrashort light pulses.

    Science.gov (United States)

    Lee, Hongki; Kim, Chulhong; Kim, Donghyun

    2015-12-02

    Near-field localization by ultrashort femtosecond light pulses has been investigated using simple geometrical nanoapertures. The apertures employ circular, rhombic, and triangular shapes to localize the distribution of surface plasmon. To understand the geometrical effect on the localization, aperture length and period of the nanoapertures were varied. Aperture length was shown to affect the performance more than aperture period due mainly to intra-aperture coupling of near-fields. Triangular apertures provided the strongest spatial localization below 10 nm in size as well as the highest enhancement of field intensity by more than 7000 times compared to the incident light pulse. Use of ultrashort pulses was found to allow much stronger light localization than with continuous-wave light. The results can be used for super-localization sensing and imaging applications where spatially localized fields can break through the limits in achieving improved sensitivity and resolution.

  9. Safety Evaluation of Self-assembling Peptide Gel after Intracranial Administration to Rats Using the Open Field Test.

    Science.gov (United States)

    Tsunoda, Masashi; Sugaya, Chiemi; Sugiura, Yumiko; Nagai, Yusuke; Sakanishi, Kotaro

    2016-01-01

    Self-assembling peptides have been developed as clinical materials, which could scaffold to regenerate nerve cells and hemostatic materials in vivo. However, there has not been enough information for their in vivo application. The safety of self-assembling peptides for the application on the brain was examined using behavioral tests for each rat in this study. Self-assembling peptide gel was administered to the surface of the brain at a volume of 20 µL at 1.5%. After 2 months, the open field test and the prepulse inhibition (PPI) test were performed. There were no significant differences between the peptide gel and the control groups in locomotor distances and in %PPIs in the PPI test. The mean values of the percentage of time the rats stayed in the central area of the open field during the first 5 min and instances of center rearing or face washing in the peptide gel group were significantly higher than those in the control. There were amorphous substance in the subarachnoid region, and infiltrations of mononuclear cells were also observed in the self-assembling peptide gel group. Although the meaning of the effects observed in this study was not fully elucidated, the self-assembling gel produced marginal but significant behavioral and histological effects.

  10. Nonlinear propagation of strong-field THz pulses in doped semiconductors

    DEFF Research Database (Denmark)

    Turchinovich, Dmitry; Hvam, Jørn Märcher; Hoffmann, Matthias C.

    2012-01-01

    We report on nonlinear propagation of single-cycle THz pulses with peak electric fields reaching 300 kV/cm in n-type semiconductors at room temperature. Dramatic THz saturable absorption effects are observed in GaAs, GaP, and Ge, which are caused by the nonlinear electron transport in THz fields....

  11. Cu-Ag alloy Bitter type magnet for repeating pulsed field

    Energy Technology Data Exchange (ETDEWEB)

    Motokawa, M.; Nojiri, H.; Mitsudo, S. [Tohoku Univ., Sendai (Japan). Inst. for Materials Research; Arai, M.; Ubukata, K.; Fujita, M.; Arakawa, T.; Inamura, Y. [Kobe Univ. (Japan). Dept. of Physics

    1996-07-01

    Cu-Ag alloy is used for the repeating pulsed field magnets. It is found that fields up to 22 T or more will be available for this purpose instead of 16 T which is obtained with normal copper magnet used at present. This result is a big advantage for neutron diffraction experiments.

  12. Photodissociation dynamics of triatomic molecule in presence of pulsed and bichromatic laser field

    Science.gov (United States)

    Ahamed Khan, Basir

    2014-04-01

    The photodissociation dynamics of a triatomic molecule in the presence of pulsed and bichromatic electric field have been investigated. We have considered MgH2 molecule in its ground state potential energy surface. The time-dependent Fourier Grid Hamiltonian method is invoked to follow the dissociation dynamics as a function of field strength, frequency, phase difference, etc.

  13. Pulse Localization and Fourier Analysis in the Mathematical Model of Acoustic Transient Field

    Directory of Open Access Journals (Sweden)

    Lukas Koudela

    2016-01-01

    Full Text Available The numerical model of a semi-cylindrical acoustic diffuser in planar transient acoustic field is discussed. The finite element method was used for the solution of the model. From the computed waveforms the straight and the reflected pulses were automatically extracted using cross-correlation. The harmonic decomposition was performed on the obtained pulses and the results were plotted in the polar pattern.

  14. A numerical solution algorithm and its application to studies of pulsed light fields propagation

    Science.gov (United States)

    Banakh, V. A.; Gerasimova, L. O.; Smalikho, I. N.; Falits, A. V.

    2016-08-01

    A new method for studies of pulsed laser beams propagation in a turbulent atmosphere was proposed. The algorithm of numerical simulation is based on the solution of wave parabolic equation for complex spectral amplitude of wave field using method of splitting into physical factors. Examples of the use of the algorithm in the case the propagation pulsed Laguerre-Gaussian beams of femtosecond duration in the turbulence atmosphere has been shown.

  15. Molecular alignment and orientation in short pulse laser fields

    DEFF Research Database (Denmark)

    Henriksen, Niels Engholm

    1999-01-01

    An analytical expression for the propagator associated with impulsive excitation is derived based on the Magnus expansion. We apply this expression to the excitation of angular motion out of a rotational eigenstate for a linear polar molecule in a plane polarized electromagnetic field. We show...... that with properly chosen field parameters, the motion of the molecule alternates between orientations in the forward and backward hemisphere, respectively, with respect to the polarization axis of the field. (C) 1999 Elsevier Science B.V. All rights reserved....

  16. High Dynamic Range Electric Field Sensor for Electromagnetic Pulse Detection

    CERN Document Server

    Lin, Che-Yun; Lee, Beom Suk; Zhang, Xingyu; Chen, Ray T

    2014-01-01

    We design a high dynamic range electric field sensor based on domain inverted electro-optic (E-O) polymer Y-fed directional coupler for electromagnetic wave detection. This electrode-less, all optical, wideband electrical field sensor is fabricated using standard processing for E-O polymer photonic devices. Experimental results demonstrate effective detection of electric field from 16.7V/m to 750KV/m at a frequency of 1GHz, and spurious free measurement range of 70dB.

  17. Estimating of pulsed electric fields using optical measurements.

    Energy Technology Data Exchange (ETDEWEB)

    Flanagan, Timothy McGuire; Chantler, Gary.

    2013-09-01

    We performed optical electric field measurements ion nanosecond time scales using the electrooptic crystal beta barium borate (BBO). Tests were based on a preliminary bench top design intended to be a proofofprinciple stepping stone towards a modulardesign optical Efield diagnostic that has no metal in the interrogated environment. The long term goal is to field a modular version of the diagnostic in experiments on large scale xray source facilities, or similarly harsh environments.

  18. The impacts of magnetic field on repetitive nanosecond pulsed dielectric barrier discharge in air

    Science.gov (United States)

    Liu, Yidi; Qi, Haicheng; Fan, Zhihui; Yan, Huijie; Ren, ChunSheng

    2016-11-01

    In this paper, the impacts of the parallel magnetic field on the repetitive nanosecond pulsed dielectric barrier discharge (DBD) are experimentally investigated by optical and electrical measurements. The DBD is generated between two parallel-plate electrodes in the ambient air with the stationary magnetic field on the order of 1 T. The experimental results show that additional microdischarge channels are generated and the photocurrent intensity of the plasma is increased by the magnetic field. The microdischarge channels develop along the magnetic field lines and the diffuse background emission of the discharge is stronger in the DBD with the magnetic field. As the pulse repetition frequency decreases from 1200 Hz to 100 Hz, only the photocurrent intensity of the third discharge that occurred at about 500 ns is noticeably increased by the additional magnetic field. It is believed that the enhancement of the memory effect and the confinement of the magnetic field on electrons are the main reasons.

  19. Ultra-low field T1 vs. T1rho at 3T and 7T: study of rotationally immobilized protein gels and animal brain tissues

    Science.gov (United States)

    Dong, Hui; Inglis, Ben; Barr, Ian; Clarke, John

    2015-03-01

    Clinical magnetic resonance imaging (MRI) machines operating in static fields of typically 1.5 T or 3 T can capture information on slow molecular dynamics utilizing the so-called T1rho technique. This technique, in which a radiofrequency (RF) spin-lock field is applied with microtesla amplitude, has been used, for example, to determine the onset time of stroke in studies on rats. The long RF pulse, however, may exceed the specific absorption rate (SAR) limit, putting subjects at risk. Ultra-low-field (ULF) MRI, based on Superconducting Quantum Interference Devices (SQUIDs), directly detects proton signals at a static magnetic field of typically 50-250 μT. Using our ULF MRI system with adjustable static field of typically 55 to 240 μT, we systematically measured the T1 and T2 dispersion profiles of rotationally immobilized protein gels (bovine serum albumin), ex vivo pig brains, and ex vivo rat brains with induced stroke. Comparing the ULF results with T1rho dispersion obtained at 3 T and 7 T, we find that the degree of protein immobilization determines the frequency-dependence of both T1 and T1rho. Furthermore, T1rho and ULF T1 show similar results for stroke, suggesting that ULF MRI may be used to image traumatic brain injury with negligible SAR. This research was supported by the Henry H. Wheeler, Jr. Brain Imaging Center and the Donaldson Trust.

  20. NMR in pulsed high-field magnets and application to high-T(C) superconductors.

    Science.gov (United States)

    Stork, H; Bontemps, P; Rikken, G L J A

    2013-09-01

    This article deals with the implementation of Nuclear Magnetic Resonance (NMR) experiments in pulsed magnetic fields at the pulsed-field facility of the Laboratoire National des Champs Magnétiques Intenses and its application to the high-T(C) superconductor YBa2Cu3O6.51. The experimental setup is described in detail, including a low-temperature probe head adapted for pulsed fields. An entire paragraph is dedicated to the discussion of NMR in pulsed field and the introduction of an advanced deconvolution technique making use of the induction voltage in an additional pick-up coil. The (63)Cu/(65)Cu NMR experiments on an YBa2Cu3O6.51 single crystal were performed at 2.5K during a field pulse of 46.8-T-amplitude. In the recorded spectrum the (63)Cu center line and high-frequency satellites as well as the (65)Cu center line are identified and are compared with results in literature.

  1. Sterilization of Escherichia coli cells by the application of pulsed magnetic field

    Institute of Scientific and Technical Information of China (English)

    LI Mei; QU Jiu-hui; PENG Yong-zhen

    2004-01-01

    The inactivation of microorganisms by pulsed magnetic field was studied. It was improved that theapplication of electromagnetic pulses evidently causes a lethal effect on E. coli cells suspended in phosphate buffersolution Na2 HPO4 / NaH2 PO4 (0.334/0.867 mmol/L). Experimental results indicated that the survivability( N/N0; whereN0 and N are the number of cells survived per milliliter before and after electromagnetic pulses application,respectively) of E. coli decreased with magnetic field intensity B and treatment time t. It was also found that themedium temperatures, the frequencies of pulse f, and the initial bacterial cell concentrations have determinateinfluences in destruction of E. coli cells by the application of magnetic pulses. The application of an magneticintensity B = 160 mT at pulses frequency f = 62 kHz and treatment time t = 16 h result in a considerable destructionlevels of E. coli cells ( N/N0 = 10-4 ). Possible mechanisms involved in sterilization of the magnetic field treatmentwere discussed. In order to shorten the treatment time, many groups of parallel inductive coil were used. Thepracticability test showed that the treatment time was shortened to 4 h with the application of three groups of parallelcoil when the survivability of E. coli cells was less than 0.01%; and the power consumption was about 0.2 kWh/m3 .

  2. Inverse problem of pulsed eddy current field of ferromagnetic plates

    Science.gov (United States)

    Chen, Xing-Le; Lei, Yin-Zhao

    2015-03-01

    To determine the wall thickness, conductivity and permeability of a ferromagnetic plate, an inverse problem is established with measured values and calculated values of time-domain induced voltage in pulsed eddy current testing on the plate. From time-domain analytical expressions of the partial derivatives of induced voltage with respect to parameters, it is deduced that the partial derivatives are approximately linearly dependent. Then the constraints of these parameters are obtained by solving a partial linear differential equation. It is indicated that only the product of conductivity and wall thickness, and the product of relative permeability and wall thickness can be determined accurately through the inverse problem with time-domain induced voltage. In the practical testing, supposing the conductivity of the ferromagnetic plate under test is a fixed value, and then the relative variation of wall thickness between two testing points can be calculated via the ratio of the corresponding inversion results of the product of conductivity and wall thickness. Finally, this method for wall thickness measurement is verified by the experiment results of a carbon steel plate. Project supported by the National Defense Basic Technology Research Program of China (Grant No. Z132013T001).

  3. Complex envelope control of pulsed accelerating fields in superconducting cavities

    CERN Document Server

    Czarski, T

    2010-01-01

    A digital control system for superconducting cavities of a linear accelerator is presented in this work. FPGA (Field Programmable Gate Arrays) based controller, managed by MATLAB, was developed to investigate a novel firmware implementation. The LLRF - Low Level Radio Frequency system for FLASH project in DESY is introduced. Essential modeling of a cavity resonator with signal and power analysis is considered as a key approach to the control methods. An electrical model is represented by the non-stationary state space equation for the complex envelope of the cavity voltage driven by the current generator and the beam loading. The electromechanical model of the superconducting cavity resonator including the Lorentz force detuning has been developed for a simulation purpose. The digital signal processing is proposed for the field vector detection. The field vector sum control is considered for multiple cavities driven by one klystron. An algebraic, complex domain model is proposed for the system analysis. The c...

  4. Pulsed Field Magnetostriction and Metamagnetism in UPt3

    Energy Technology Data Exchange (ETDEWEB)

    Shivaram, B. [Univ. of Virginia, Charlottesville, VA (United States); Weickert, Dagmar Franziska [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Jaime, Marcelo [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-03-01

    Metamagnetism (MM) characterized by a sudden rise in the magnetization at a critical field is a well established phenomenon in the hexagonal system UPt3, first noted at H = 20 T nearly three decades ago. However recent detailed measurements of the nonlinear magnetic susceptibility has raised new questions. With a careful analysis of the existing data and utilizing a phenomenological single energy scale (SES) model developed in this context one of us (BSS) was able to show that there is a distinct possibility of a second MM transition at a higher field. Depending upon the parameters chosen in the model this transition is predicted to occur in the range of 60 T-100 T. Thus measurements of the magnetic and magnetoelastic properties of UPt3 in the highest available fields is desirable.

  5. Strong-field QED processes in short laser pulses. One- and two-photon Compton scattering

    Energy Technology Data Exchange (ETDEWEB)

    Seipt, Daniel

    2012-12-20

    The purpose of this thesis is to advance the understanding of strong-field QED processes in short laser pulses. The processes of non-linear one-photon and two-photon Compton scattering are studied, that is the scattering of photons in the interaction of relativistic electrons with ultra-short high-intensity laser pulses. These investigations are done in view of the present and next generation of ultra-high intensity optical lasers which are supposed to achieve unprecedented intensities of the order of 10{sup 24} W/cm{sup 2} and beyond, with pulse lengths in the order of some femtoseconds. The ultra-high laser intensity requires a non-perturbative description of the interaction of charged particles with the laser field to allow for multi-photon interactions, which is beyond the usual perturbative expansion of QED organized in powers of the fine structure constant. This is achieved in strong-field QED by employing the Furry picture and non-perturbative solutions of the Dirac equation in the presence of a background laser field as initial and final state wave functions, as well as the laser dressed Dirac-Volkov propagator. The primary objective is a realistic description of scattering processes with regard to the finite laser pulse duration beyond the common approximation of infinite plane waves, which is made necessary by the ultra-short pulse length of modern high-intensity lasers. Non-linear finite size effects are identified, which are a result of the interplay between the ultra-high intensity and the ultra-short pulse length. In particular, the frequency spectra and azimuthal photon emission spectra are studied emphasizing the differences between pulsed and infinite laser fields. The proper description of the finite temporal duration of the laser pulse leads to a regularization of unphysical infinities (due to the infinite plane-wave description) of the laser-dressed Dirac-Volkov propagator and in the second-order strong-field process of two-photon Compton

  6. Research on the Pulsed Magnetic Field Device for Sterilization of Fruit and Vegetable Equipment

    Directory of Open Access Journals (Sweden)

    Liu Mingdan

    2013-04-01

    Full Text Available In view of the requests of the sterilization device of the fruit and vegetable that integrate cleaning and juicing together, and combined with the electromagnetic theory and the cold sterilization technology which is in common use in modern food industry, circuits are designed for the pulsed magnetic field sterilization device of the integrated machine .This circuits chose a linear solenoid in which r= 30mm, l= 200 mm. The experiment shows that the pulsed magnetic field produced by the device can achieve a better effect in killing bacillus coli, beer yeast and staphylococcus aurous, etc. Compared with the traditional sterilization device, the bactericidal effect of the pulsed magnetic field sterilization device is more obvious so that it will be the direction of the development of food equipments. [1]  

  7. Interactions of Low-Frequency, Pulsed Electromagnetic Fields with Living Tissue: Biochemical Responses and Clinical Results

    DEFF Research Database (Denmark)

    Rahbek, Ulrik L.; Tritsaris, Katerina; Dissing, Steen

    2005-01-01

    In recent years many studies have demonstrated stimulatory effects of pulsed electromagnetic fields (PEMF) on biological tissue. However, controversies have also surrounded the research often due to the lack of knowledge of the different physical consequences of static versus pulsed electromagnetic...... fields. PEMF is widely used for treating fractures and non-unions as well as for treating diseases of the joints. Furthermore, new research has suggested that the technology can be used for nerve regeneration and wound healing although conclusive clinical trials, besides those for fracture healing......, are still lacking. Despite the apparent success of the PEMF technology very little is known regarding the coupling between pulsed electrical fields and biochemical events leading to cellular responses. Insight into this research area is therefore of great importance. In this review we describe the physical...

  8. A novel application of pulsed electric field (PEF) processing for improving glutathione (GSH) antioxidant activity.

    Science.gov (United States)

    Wang, Jia; Wang, Ke; Wang, Ying; Lin, Songyi; Zhao, Ping; Jones, Gregory

    2014-10-15

    Glutathione (GSH) was treated by pulsed electric field (PEF) processing to investigate its effect on antioxidant activity. The antioxidant activity of GSH was evaluated using 2,2-diphenyl-1-picrylhydrazy (DPPH) radical inhibition. A Box-Behnken design (BBD) with three independent variables, which were concentration, electric field intensity and pulse frequency was used to establish the regression equation of second-order response surface. Optimal conditions were as follows: GSH concentration 8.86mg/mL, electric field intensity 9.74kV/cm and pulse frequency 2549.08Hz. The DPPH radical inhibition increased from 81.83% to 97.40%. Near-infrared spectroscopy (NIR) and mid-infrared spectroscopy (MIR) were used to analyse the change of structure and functional groups of GSH.

  9. A Pulsed Electric Field (PEF) bench static system to study bacteria inactivation

    Energy Technology Data Exchange (ETDEWEB)

    Cortese, Pietro; Dellacasa, Giuseppe; Gemme, Roberto [Department of Science and Advanced Technology, Eastern Piedmont University, Viale Teresa Michel 11, 15121-Alessandria (Italy); Bonetta, Sara; Bonetta, Silvia; Carraro, Elisabetta; Motta, Francesca [Department of Environmental and Life Science, Eastern Piedmont University, Viale Teresa Michel 11, 15121-Alessandria (Italy); Paganoni, Marco; Pizzichemi, Marco [Physics Department G. Occhialini, University of Milano-Bicocca, Piazza della Scienza 3, 20126-Milano (Italy)

    2011-06-15

    Pulsed Electric Fields (PEF) technology is a promising non-thermal processing method for inactivation of microorganisms. A small PEF bench system able to treat a 0.4 ml static liquid volume has been built and tested at the laboratories of the Universita del Piemonte Orientale in Alessandria, Italy. The technique used to produce the required fields consists of charging high voltage cables of various lengths and subsequently discharge them on a cylindrical cell. The pulse intensity can be adjusted to reach a maximum electric field in the cell of about 35 kV/cm and the pulse frequency can reach 10 Hz. We describe the PEF system in some detail and, as a benchmark of its performances, we report preliminary results obtained on Escherichia coli (ATCC 25922) at 10{sup 9} Cfu/ml concentration suspended in a McIlvaine buffer (pH 7.2).

  10. Pre-breakdown cavitation development in the dielectric fluid in the inhomogeneous, pulsed electric fields

    CERN Document Server

    Shneider, Mikhail N

    2014-01-01

    We consider the development of pre-breakdown cavitation nanopores appearing in the dielectric fluid under the influence of the electrostrictive stresses in the inhomogeneous pulsed electric field. It is shown that three characteristic regions can be distinguished near the needle electrode. In the first region, where the electric field gradient is greatest, the cavitation nanopores, occurring during the voltage nanosecond pulse, may grow to the size at which an electron accelerated by the field inside the pores can acquire enough energy for excitation and ionization of the liquid on the opposite pore wall, i.e., the breakdown conditions are satisfied. In the second region, the negative pressure caused by the electrostriction is large enough for the cavitation initiation (which can be registered by optical methods), but, during the voltage pulse, the pores do not reach the size at which the potential difference across their borders becomes sufficient for ionization or excitation of water molecules. And, in the ...

  11. A 3He Cryostat for Scientific Measurements in Pulsed High Magnetic Fields

    Science.gov (United States)

    Wang, Shaoliang; Li, Liang; Liu, Mengyu; Zuo, Huakun; Peng, Tao

    A top loading 3He cryostat has been developed for scientific experiments with a 60 T pulsed magnetic field facility at Wuhan National High Magnetic Field Center. The cryostat consists of a 4He bath cryostat, a 3He insert and a closed circulation system for 3He gas handling. To eliminate the eddy current heating during the pulse, the tail of the 3He insert with a vacuum space at the bottom is made from fiberglass tubing coated with epoxy. The 3He bath is separated from the 4He bath with the vacuum space. The 4He bath cryostat provides cooling power to condense 3He gas by a neck tube on top of the tail. Experimental results have shown that the sample can be cooled down to 385 mK and kept cold for more than 150 second by one-shot cooling, which is sufficiently long for an experiment in a pulsed high magnetic field.

  12. Modification of Pulsed Electric Field Conditions Results in Distinct Activation Profiles of Platelet-Rich Plasma

    Science.gov (United States)

    Frelinger, Andrew L.; Gerrits, Anja J.; Garner, Allen L.; Torres, Andrew S.; Caiafa, Antonio; Morton, Christine A.; Berny-Lang, Michelle A.; Carmichael, Sabrina L.; Neculaes, V. Bogdan; Michelson, Alan D.

    2016-01-01

    Background Activated autologous platelet-rich plasma (PRP) used in therapeutic wound healing applications is poorly characterized and standardized. Using pulsed electric fields (PEF) to activate platelets may reduce variability and eliminate complications associated with the use of bovine thrombin. We previously reported that exposing PRP to sub-microsecond duration, high electric field (SMHEF) pulses generates a greater number of platelet-derived microparticles, increased expression of prothrombotic platelet surfaces, and differential release of growth factors compared to thrombin. Moreover, the platelet releasate produced by SMHEF pulses induced greater cell proliferation than plasma. Aims To determine whether sub-microsecond duration, low electric field (SMLEF) bipolar pulses results in differential activation of PRP compared to SMHEF, with respect to profiles of activation markers, growth factor release, and cell proliferation capacity. Methods PRP activation by SMLEF bipolar pulses was compared to SMHEF pulses and bovine thrombin. PRP was prepared using the Harvest SmartPreP2 System from acid citrate dextrose anticoagulated healthy donor blood. PEF activation by either SMHEF or SMLEF pulses was performed using a standard electroporation cuvette preloaded with CaCl2 and a prototype instrument designed to take into account the electrical properties of PRP. Flow cytometry was used to assess platelet surface P-selectin expression, and annexin V binding. Platelet-derived growth factor (PDGF), vascular endothelial growth factor (VEGF), endothelial growth factor (EGF) and platelet factor 4 (PF4), and were measured by ELISA. The ability of supernatants to stimulate proliferation of human epithelial cells in culture was also evaluated. Controls included vehicle-treated, unactivated PRP and PRP with 10 mM CaCl2 activated with 1 U/mL bovine thrombin. Results PRP activated with SMLEF bipolar pulses or thrombin had similar light scatter profiles, consistent with the

  13. Characterisation of practical high temperature superconductors in pulsed magnetic fields and development of associated technology

    CERN Document Server

    Saleh, P M

    2000-01-01

    including a innovative design of a 100ms pulsed magnet solenoid. Critical current measurements on state of the art practical high temperature superconductors are presented. Bi sub 2 Sr sub 2 CaCu sub 2 O silver-alloy matrix powder-in-tube and silver-alloy substrate dip-coated tapes, formed into various geometries, have been tested in pulsed magnetic fields of various pulse lengths. These measurements have been compared to tests performed in continuous magnetic fields. A distinct discrepancy between pulsed and continuous measurements has been observed in these silver-alloy, high temperature superconductor composites. The critical current measured in pulsed fields is depressed compared to those measured in continuous fields. Evidence is provided to strongly suggest that eddy current heating in the silver-alloy substrate/sheath of the conductor is responsible for this discrepancy. A model is presented to predict the temperature rise due to eddy current heating. This model shows good agreement with observations. ...

  14. Pulsed and streamer discharges in air above breakdown electric field

    NARCIS (Netherlands)

    Sun, A.B.; Teunissen, H.J.; Ebert, U.

    2013-01-01

    A 3D particle model is developed to investigate the streamer formation in electric fields above the breakdown threshold, in atmospheric air (1bar, 300 Kelvin). Adaptive particle management, adaptive mesh refinement and parallel computing techniques are used in the code. Photoionization and electron

  15. The effects of amylose and starch phosphate on starch gel retrogradation studied by low-field 1H NMR relaxometry

    DEFF Research Database (Denmark)

    Thygesen, Lisbeth Garbrecht; Blennow, A.; Engelsen, S. B.

    2003-01-01

    ) relaxation curves from the two measurements (day 1 and day 7) could be used as a simple, illustrative way of describing the retrogradation. Three different behaviours were identified: One group of samples (mostly potato starches) slowly changed from a soft to a more rigid gel from day 1 to 7. A second group...... (mostly cereal starches) formed a rigid gel already before the first measurement and changed little after that. A third group comprised a few samples containing little or no amylose aged similarly to the first group of samples, but at a much slower rate. For the potato starches, a weak negative......Low-field Nuclear Magnetic Resonance (23 MHz) was used to study the effects of the degree of phosphorylation, the amylose content and the amylopectin chain length distribution on gel retrogradation for a set of 26 starches, six of which were of crystal polymorph type A, 18 of type B and two of type...

  16. Is pulsed electric field still effective for RNA separation in capillary electrophoresis?

    Science.gov (United States)

    Li, Zhenqing; Dou, Xiaoming; Ni, Yi; Chen, Qinmiao; Cheng, Shuyi; Yamaguchi, Yoshinori

    2012-03-16

    Pulsed field capillary electrophoresis (PFCE) is a predominant technique to cope with difficulties in resolving large DNA strands, yet it is still unclear whether pulsed electric field is effective for the separation of higher mass RNA. In this paper we focused on the role of pulsed electric field in large RNA fragments analysis by comparing RNA separation performance in PFCE with that in constant field CE. Separation performance in terms of migration mobility, plate numbers, resolution, and selectivity has been tested for the analysis of RNA from 0.1 to 10.0 kilo nucleotide (knt) under different electrophoretic conditions. Denaturation, important to obtain uniform and identifiable peaks, was accomplished by heating the sample in 4.0M urea prior to analysis and the presence of 4.0M urea in the electrophoresis buffer. Results demonstrate that unlike DNA in PFCE, the pulsed electric field mainly affects the separation performance of RNA between 0.4 and 2.0 knt. The migration mobility of long RNA fragments is not a strong function of modulation depth and pulsed frequency. Moreover, the logarithm of RNA mobility is almost inversely proportional to the logarithm of molecule size up to 6.0 knt with correlation coefficient higher than 0.99 in all the polymer concentrations measured here. Resonance frequency of RNA in PFCE was also observed. While these initial experiments show no distinct advantages of using PFCE for RNA separation, they do take further step toward characterizing the migration behavior of RNA under pulsed field conditions.

  17. Quantum ring states in magnetic field and delayed half-cycle pulses

    Indian Academy of Sciences (India)

    KRITI BATRA; HIRA JOSHI; VINOD PRASAD

    2016-08-01

    The present work is dedicated to the time evolution of excitation of a quantum ring in external electric and magnetic fields. Such a ring of mesoscopic dimensions in an external magnetic field is known to exhibit a wide variety of interesting physical phenomena. We have studied the dynamics of the single electron quantum ring in the presence of a static magnetic field and a combination of delayed half-cycle pulse pair. Detailed calculations have been worked out and the impact on dynamics by variation in the ring radius, intensity of external electric field, delay between the two pulses, and variation in magnetic field have been reported. A total of 19 states have been taken and the population transfer in the single electron quantum ring is studied by solving the time-dependent Schrödinger equation (TDSE), using the efficient fourth-order Runge--Kutta method. Many interesting features have been observed in the transition probabilities with the variation of magnetic field, delay between pulses and ring dimensions. A very important aspect of the present work is the persistent current generation in a quantum ring in the presence of external magnetic flux and its periodic variation with the magnetic flux, ring dimensions and pulse delay.

  18. Pulsed magnetic field excitation sensitivity of match-type electric blasting caps.

    Science.gov (United States)

    Parson, Jonathan; Dickens, James; Walter, John; Neuber, Andreas A

    2010-10-01

    This paper presents a study on energy deposition and electromagnetic compatibility of match-type electroexplosive devices (EEDs), which recently have found more usage in pulsed power environments with high electromagnetic interference (EMI) background. The sensitivity of these devices makes them dangerous to intended and unintended radiation produced by devices commonly used in pulsed power environments. Match-type EEDs have been found to be susceptible to such low levels of energy (7-8 mJ) that safe operation of these EEDs is vital when in use near devices that produce high levels of pulsed EMI. The scope of this paper is to provide an investigation that incorporates results of similar studies to provide detonation characteristics of these EEDs. The three topics included in this study are sensitivity testing, modeling of the thermodynamic heat propagation, and electromagnetic compatibility from pulsed electromagnetic radiation. The thermodynamic joule heating of the primary explosive has been modeled by a solution to the 1D heat equation. A simple pulsed generator, Marx generator with an inductive load, was used for the electromagnetic compatibility assessment of the coupled field between the pulse generator and shorted EED. The results of the electromagnetic compatibility assessment relate the resistive, inductive, and capacitive components of the pulse generator to the area of the shorted EED.

  19. A compact field-portable double-pulse laser system to enhance laser induced breakdown spectroscopy

    Science.gov (United States)

    Li, Shuo; Liu, Lei; Yan, Aidong; Huang, Sheng; Huang, Xi; Chen, Rongzhang; Lu, Yongfeng; Chen, Kevin

    2017-02-01

    This paper reports the development of a compact double-pulse laser system to enhance laser induced breakdown spectroscopy (LIBS) for field applications. Pumped by high-power vertical-surface emitting lasers, the laser system that produces 16 ns pulse at 12 mJ/pulse with total weight less than 10 kg is developed. The inter-pulse delay can be adjusted from 0 μ s with 0.5 μ s increment. Several LIBS experiments were carried out on NIST standard aluminum alloy samples. Comparing with the single-pulse LIBS, up to 9 times enhancement in atomic emission line was achieved with continuum background emission reduced by 70%. This has led to up to 10 times improvement in the limit of detection. Signal stability was also improved by 128% indicating that a more robust and accurate LIBS measurement can be achieved using a compact double-pulse laser system. This paper presents a viable and field deployable laser tool to dramatically improve the sensitivity and applicability of LIBS for a wide array of applications.

  20. Pulsed laser deposition of graphite in air and in vacuum for field emission studies

    Energy Technology Data Exchange (ETDEWEB)

    Jadhav, Harshada; Singh, A.K.; Sinha, Sucharita, E-mail: ssinha@barc.gov.in

    2015-07-15

    A comparative study of pulsed laser deposition (PLD) based carbon films when deposited either, in atmospheric air, or under vacuum, has been performed. Micro-structural characterization of deposited films was carried out employing X-ray diffraction and Raman spectroscopic techniques. While, nanocrystalline graphite phase was observed in carbon films deposited in air, PLD films deposited under vacuum were largely amorphous in nature. Field emission (FE) properties of films deposited in air and under vacuum were investigated. Superior FE behavior characterized by a lower turn-on field (2.72 V/μm) and high field enhancement factor (∼2580) was observed for PLD films deposited in air. This improved field emission demonstrated by carbon films deposited via PLD in air can be attributed to presence of nanocrystalline graphite aggregates in such carbon films and local field enhancement near the sp{sup 2} sites. Our results therefore, establish PLD in air as a simple technique for deposition of carbon films having good field emission capability. - Highlights: • Pulsed laser deposition of graphite films, deposited in air and in vacuum. • Micro-structural, X-ray diffraction and micro-Raman spectroscopic characterization of deposited films. • Field emission properties of deposited films investigated. • Superior field emission behavior observed for films deposited in air than in vacuum. • Pulsed laser deposition in air leads to carbon films with excellent field emission capability.

  1. Use of a probing pulsed magnetic field for determining plasma parameters

    Science.gov (United States)

    Rousskikh, A. G.; Oreshkin, V. I.; Zhigalin, A. S.; Yushkov, G. Yu.

    2016-11-01

    A novel, simple, and readily usable method is proposed for measuring the electrical conductivity and temperature of a plasma. The method is based on the interaction of the test plasma with a pulsed magnetic field. The electric signals induced by the magnetic field in the circuits of two probes (miniature solenoids), one immersed in the test plasma and the other placed outside the plasma, provide data for estimating the plasma parameters. The method was verified experimentally by determining the parameters of the plasma flows generated in the cathode spots high-current pulsed vacuum arcs that were used to form cylindrical shells of bismuth Z-pinch plasma.

  2. Unipolar magnetic field pulses as transient signals prior to the 2009 Aquila earthquake shock

    CERN Document Server

    Nenovski, Petko

    2016-01-01

    Unipolar pre-seismic magnetic field pulses have been observed first by Bleier et al. (2009) and Villante et al. (2010) and Nenovski et al. (2013). In the present study a detailed analysis of the pulses is conducted looking for signatures of transient signals similar to that recorded at the 2009 Aquila earthquake main shock (Nenovski, 2015). Various magnetic field data around the Aquila earthquake provide an instrumental basis for such an analysis. In addition to fluxgate magnetometer data (already examined in previous studies), overhauser magnetometer data are involved. The result is a detection and discrimination of transient signals of diffusive form that appear prior to the earthquake main shock.

  3. Influence of laser pulse on the autocorrelation function of H in a strong electric field

    Institute of Scientific and Technical Information of China (English)

    Lifei Wang; Guangcan Yang

    2009-01-01

    The autocorrelation function of electronic wave packet of hydrogen atom in a strong electric field below the zero-field ionization threshold is investigated in the formalism of semiclassical theory. It is found that the autocorrelation depends on the applied laser pulse significantly. In the case of narrow laser pulse, the reviving peaks in the autocorrelation can be attributed to the closed orbits of electrons, which are related to the classical dynamics of the system. But this correspondence is wiped out with increasing the laser width because of the interference among the adjacent reviving peaks.

  4. Simulation and experiments of stacks of high temperature superconducting coated conductors magnetized by pulsed field magnetization with multi-pulse technique

    Science.gov (United States)

    Zou, Shengnan; Zermeño, Víctor M. R.; Baskys, A.; Patel, A.; Grilli, Francesco; Glowacki, B. A.

    2017-01-01

    High temperature superconducting bulks or stacks of coated conductors (CCs) can be magnetized to become trapped field magnets (TFMs). The magnetic fields of such TFMs can break the limitation of conventional magnets (low cost. However, due to the heat generation during the magnetization, the trapped field and flux acquired by PFM usually cannot achieve the full potential of a sample (acquired by the field cooling or zero field cooling method). The multi-pulse technique was found to effectively improve the trapped field by PFM in practice. In this work, a systematic study on the PFM with successive pulses is presented. A 2D electromagnetic-thermal coupled model with comprehensive temperature dependent parameters is used to simulate a stack of CCs magnetized by successive magnetic pulses. An overall picture is built to show how the trapped field and flux evolve with different pulse sequences and the evolution patterns are analyzed. Based on the discussion, an operable magnetization strategy of PFM with successive pulses is suggested to provide more trapped field and flux. Finally, experimental results of a stack of CCs magnetized by typical pulse sequences are presented for demonstration.

  5. Size separation of DNA molecules by pulsed electric field dielectrophoresis

    Energy Technology Data Exchange (ETDEWEB)

    Nedelcu, S [National Institute for R and D in Microtechnologies, Str. Erou Iancu Nicolae 32B, PO Box 38-160, 023573 Bucharest (Romania); Watson, J H P [School of Physics and Astronomy, University of Southampton, Highfield, SO17 1BJ, Southampton (United Kingdom)

    2004-08-07

    In this paper we propose an electrode design and a switching pattern of the applied DC electrode potentials for a microfluidic device to be used in size separation of DNA molecules. Estimates on the separation resolution, which are based on numerical solutions of a Newton-type equation on time-averaged quantities, are presented for an input batch sample of DNA fragments with sizes up to 220 base pairs (bp). The active area of the device (which can be microfabricated by standard photolitographic techniques) is a channel 6 {mu}m wide, 8 {mu}m deep and 150 {mu}m in length, flanked by 23 plane parallel integrated electrodes, individually addressed with low DC voltages, up to {+-} 25 V. In the active area a time-dependent non-uniform electric field, or a travelling dielectrophoretic wave (TDW) is being produced. In order to enhance the separation resolution, the polarization DC potentials are switched with a relatively high frequency ({approx} 10{sup -7} s), which is chosen accordingly with the buffer conductivity and dielectric constants of the fluid and particles. Since the external field is of DC type, we put forward an explanatory model of the dielectric response of the DNA to the time-dependent applied field. We then numerically investigate the size-dependent response of the DNA in a low conductivity buffer ({approx}0.01 {omega}{sup -1} m{sup -1}) under the influence of the electric field, which is calculated by means of the method of moments. The results of the computer modelling indicate the existence of a threshold value for the size of the successfully transported molecules, which can be adjusted by varying the velocity of the dielectrophoretic wave produced by the system. The estimated error in selecting a chosen group of molecules with sizes above a specified value is about 5 bp, while the processing times are of the order of hundred of seconds.

  6. Nonadiabatic dynamics and multiphoton resonances in strong field molecular ionization with few cycle laser pulses

    CERN Document Server

    Tagliamonti, Vincent; Zhao, Arthur; Rozgonyi, Tamás; Marquetand, Philipp; Weinacht, Thomas

    2016-01-01

    We study strong field molecular ionization using few- (four to ten) cycle laser pulses. Employing a supercontinuum light source, we are able to tune the optical laser wavelength (photon energy) over a range of about $\\sim$200 nm (500 meV). We measure the photoelectron spectrum for a series of different molecules as a function of laser intensity, frequency, and bandwidth and illustrate how the ionization dynamics vary with these parameters. We find that multiphoton resonances and nonadiabatic dynamics (internal conversion) play an important role and result in ionization to different ionic continua. Interestingly, while nuclear dynamics can be "frozen" for sufficiently short laser pulses, we find that resonances strongly influence the photoelectron spectrum and final cationic state of the molecule regardless of pulse duration -- even for pulses that are less than four cycles in duration.

  7. Pulse width effect on the dissociation probability of CH4+ in the intense femtosecond laser field

    Institute of Scientific and Technical Information of China (English)

    WANG Gao; SONG Di; LIU Yuyan; KONG Fan'ao

    2006-01-01

    The laser pulse width effect on the dissociation probability of CH4+ irradiated by an ultrafast laser has been investigated experimentally and theoretically. The femtosecond laser at 800 nm with an intensity of 8.0 × 1013 W/cm2 was used. The observed relative yield of the primary fragment ion CH3+ increases with increasing pulse width and tends to saturate when the pulse width is longer than 120 fs. The field-assisted dissociation (FAD) model and quasi-classical trajectory (QCT) calculation were applied to predicting the dissociation probability of CH4+.The calculated probability is corrected with the molecular orientation effect and the spatial distribution of laser intensity. The modified results show that the dissociation requires at least 23 fs and saturates with long pulse widths (≥100 rs). The result is approximately consistent with the experimental observation.

  8. Nine Channel Mid-Power Bipolar Pulse Generator Based on a Field Programmable Gate Array

    CERN Document Server

    Haylock, Ben; Kasture, Sachin; Fisher, Paul; Streed, Erik W; Lobino, Mirko

    2016-01-01

    Many channel arbitrary pulse sequence generation is required for the electro-optic reconfiguration of optical waveguide networks in Lithium Niobate. Here we describe a scalable solution to the requirement for mid-power bipolar parallel outputs, based on pulse patterns generated by an externally clocked field programmable gate array (FPGA). Positive and negative pulses can be generated at repetition rates from up to 80~MHz with pulse width adjustable in increments of 1.6~ns across nine independent outputs. Each channel can provide 1.5W of RF power and it can be synchronised with the operation of other components in an optical network such as light sources and detectors through an external clock with adjustable delay.

  9. Flux motion in Y-Ba-Cu-O bulk superconductors during pulse field magnetization

    Energy Technology Data Exchange (ETDEWEB)

    Yoshizawa, K [Department of Physics, College of Humanities and Sciences, Nihon University, 3-25-40 Sakura-Josui, Setagaya-ku, Tokyo 156-8550 (Japan); Nariki, S [Division of Material Science and Physics, Bulk Superconductor Laboratory, 1-16-25 Shibaura, Minato-ku, Tokyo 105-0023 (Japan); Sakai, N [Division of Material Science and Physics, Bulk Superconductor Laboratory, 1-16-25 Shibaura, Minato-ku, Tokyo 105-0023 (Japan); Murakami, M [Division of Material Science and Physics, Bulk Superconductor Laboratory, 1-16-25 Shibaura, Minato-ku, Tokyo 105-0023 (Japan); Hirabayasi, I [Division of Material Science and Physics, Bulk Superconductor Laboratory, 1-16-25 Shibaura, Minato-ku, Tokyo 105-0023 (Japan); Takizawa, T [Department of Physics, College of Humanities and Sciences, Nihon University, 3-25-40 Sakura-Josui, Setagaya-ku, Tokyo 156-8550 (Japan)

    2004-02-01

    We have studied the relationship between the magnetization and temperature change in Y-Ba-Cu-O bulk superconductor during pulse field magnetization (PFM). The flux motion was monitored using both Hall sensors and pick-up coils that are placed on a surface of a Y-Ba-Cu-O disc having dimensions of 15 mm in diameter and 0.95 mm in thickness. The peak value of the field was varied from 0.2 to 0.8 T. The effect of the static bias field was also studied in the range of 0-3 T. The temperature of the sample surface was measured using a resistance temperature sensor. The temperature increased with the magnitude of the applied pulsed magnetic field, and the amount of temperature rise decreased with increasing static bias field.

  10. High impact ionization rate in silicon by sub-picosecond THz electric field pulses (Conference Presentation)

    DEFF Research Database (Denmark)

    Tarekegne, Abebe Tilahun; Iwaszczuk, Krzysztof; Hirori, Hideki

    2017-01-01

    Summary form only given. Metallic antenna arrays fabricated on high resistivity silicon are used to localize and enhance the incident THz field resulting in high electric field pulses with peak electric field strength reaching several MV/cm on the silicon surface near the antenna tips. In such high...... electric field strengths high density of carriers are generated in silicon through impact ionization process. The high density of generated carriers induces a change of refractive index in silicon. By measuring the change of reflectivity of tightly focused 800 nm light, the local density of free carriers...... near the antenna tips is measured. Using the NIR probing technique, we observed that the density of carriers increases by over 8 orders of magnitude in a time duration of approximately 500 fs with an incident THz pulse of peak electric field strength 700 kV/cm. This shows that a single impact...

  11. A game of RF and gradient pulses: Obtaining an efficient homogeneous flip angle with strong inhomogeneous B1 fields

    NARCIS (Netherlands)

    van Kalleveen, IML

    2016-01-01

    Adiabatic RF pulses are useful pulses for inhomogeneous B1 fields caused by surface RF coils, however the increase in SAR will lengthen the TR, and possibly also the TE if the adiabatic pulses become too long. Using the superadiabaticity theorem the increase in SAR can already be reduced, making it

  12. Nanoparticle mediated thermal ablation of breast cancer cells using a nanosecond pulsed electric field.

    Science.gov (United States)

    Burford, Christopher D; Bhattacharyya, Kiran D; Boriraksantikul, Nattaphong; Whiteside, Paul J D; Robertson, Benjamin P; Peth, Sarah M; Islam, Naz E; Viator, John A

    2013-06-01

    In the past, ablation of cancer cells using radiofrequency heating techniques has been demonstrated, but the current methodology has many flaws, including inconsistent tumor ablation and significant ablation of normal cells. Other researchers have begun to develop a treatment that is more selective for cancer cells using metallic nanoparticles and constant electric field exposure. In these studies, cell necrosis is induced by heating antibody functionalized metallic nanoparticles attached to cancer cells. Our approach to studying this phenomenon is to use similarly functionalized metallic nanoparticles that are specific for the T47D breast cancer cell line, exposing these nanoparticle cell conjugates to a nanosecond pulsed electric field. Using fluorescent, polystyrene-coated, iron-oxide nanoparticles, the results of our pilot study indicated that we were able to ablate up to approximately 80% of the cells using 60 ns pulses in increasing numbers of pulses and up to approximately 90% of the cells using 300 ns pulses in increasing numbers of pulses. These quantities of ablated cells were achieved using a cumulative exposure time 6 orders of magnitude less than most in vitro constant electric field studies.

  13. An Optimization of Pulsed ElectroMagnetic Fields Study

    Science.gov (United States)

    Goodwin, Thomas J.

    2006-01-01

    To date, in our research we have focused on the use of normal human neuronal progenitor (NHNP) cells because of their importance in human nervous system regeneration, development and maintenance, but we have developed 2-D and 3-D bioreactors that can accommodate any cell line. In this Project, we will include the use of tissues important for physiological regeneration: Human osteoblasts or chondrocytes, and vascular cells. Our initial results with the NHNP cells were quite startling using extremely low-level electromagnetic fields (5 microtesla at 10Hz; 6mA). The low-amplitude, rapidly time-varying electromagnetic fields exert a very potent effect on the proliferation, morphology, and gene expression of the cells in culture, both in standard 2-dimensional culture plates as well as cells organized into 3-dimensional tissue-like assemblies (TLAs) in a 3D bioreactor. We have replicated our preliminary results many, many times, have analyzed the gene expression using gene arrays (followed by Luminex analysis for protein production), and have monitored cell proliferation, orientation, morphology, and glucose metabolism, and we are confident that we have a stable and reliable model to study the control of high-level cellular processes by application of low-amplitude, time varying electromagnetic fields (TVEMF) (1, 2). In additional studies at the University of Michigan, we have been able to generate functional in vitro engineered mammalian skeletal muscle, and have employed nerve-muscle co-culture techniques to promote axonal sprouting. We believe that nearly all tissues, in particular, neural, are susceptible to the influences of low-level TVEMF.

  14. Field trial of a pulsed limestone diversion well

    Science.gov (United States)

    Sibrell, Philip L.; Denholm, C.; Dunn, Margaret

    2013-01-01

    The use of limestone diversion wells to treat acid mine drainage (AMD) is well-known, but in many cases, acid neutralization is not as complete as would be desired. Reasons for this include channeling of the water through the limestone bed, and the slow reaction rate of the limestone gravel. A new approach to improve the performance of the diversion well was tested in the field at the Jennings Environmental Education Center, near Slippery Rock, PA. In this approach, a finer size distribution of limestone was used so as to allow fluidization of the limestone bed, thus eliminating channeling and increasing particle surface area for faster reaction rates. Also, water flow was regulated through the use of a dosing siphon, so that consistent fluidization of the limestone sand could be achieved. Testing began late in the summer of 2010, and continued through November of 2011. Initial system performance during the 2010 field season was good, with the production of net alkaline water, but hydraulic problems involving air release and limestone sand retention were observed. In the summer of 2011, a finer size of limestone sand was procured for use in the system. This material fluidized more readily, but acid neutralization tapered off after several days. Subsequent observations indicated that the hydraulics of the system was compromised by the formation of iron oxides in the pipe leading to the limestone bed, which affected water distribution and flow through the bed. Although results from the field trial were mixed, it is believed that without the formation of iron oxides and plugging of the pipe, better acid neutralization and treatment would have occurred. Further tests are being considered using a different hydraulic configuration for the limestone sand fluidized bed.

  15. Electric field in an AC dielectric barrier discharge overlapped with a nanosecond pulse discharge

    Science.gov (United States)

    Goldberg, Benjamin M.; Shkurenkov, Ivan; Adamovich, Igor V.; Lempert, Walter R.

    2016-08-01

    The effect of ns discharge pulses on the AC barrier discharge in hydrogen in plane-to-plane geometry is studied using time-resolved measurements of the electric field in the plasma. The AC discharge was operated at a pressure of 300 Torr at frequencies of 500 and 1750 Hz, with ns pulses generated when the AC voltage was near zero. The electric field vector is measured by ps four-wave mixing technique, which generates coherent IR signal proportional to the square of electric field. Absolute calibration was done using an electrostatic (sub-breakdown) field applied to the discharge electrodes, when no plasma was generated. The results are compared with one-dimensional kinetic modeling of the AC discharge and the nanosecond pulse discharge, predicting behavior of both individual micro-discharges and their cumulative effect on the electric field distribution in the electrode gap, using stochastic averaging based on the experimental micro-discharge temporal probability distribution during the AC period. Time evolution of the electric field in the AC discharge without ns pulses, controlled by a superposition of random micro-discharges, exhibits a nearly ‘flat top’ distribution with the maximum near breakdown threshold, reproduced quite well by kinetic modeling. Adding ns pulse discharges on top of the AC voltage waveform changes the AC discharge behavior in a dramatic way, inducing transition from random micro-discharges to a more regular, near-1D discharge. In this case, reproducible volumetric AC breakdown is produced at a well-defined moment after each ns pulse discharge. During the reproducible AC breakdown, the electric field in the plasma exhibits a sudden drop, which coincides in time with a well-defined current pulse. This trend is also predicted by the kinetic model. Analysis of kinetic modeling predictions shows that this effect is caused by large-volume ionization and neutralization of surface charges on the dielectrics by ns discharge pulses. The present

  16. Pulsed mixed n, {gamma} radiation fields for electronic testing

    Energy Technology Data Exchange (ETDEWEB)

    Nurdin, G.; Becret, C.; Jaureguy, J.C. [Etablissement Technique Central de l`Armement (ETCA), 94 - Arcueil (France); Vie, M.; Baboulet, J.P.; Lapeyre, P.; Ramisse, D. [D.G.A., 46 - Gramat (France)

    1994-12-31

    For combined n, {gamma} TREE testing we have modified the CALIBAN Fast Burst Reactor Field with CdO/Epoxy converters to cover the range [10{sup 11} -10{sup 12}] n.cm{sup -2} (1 MeV Si), [10{sup 7} - 10{sup 8}] cGy(Si).s{sup -1}. Activation and fission {sigma} {phi}vector, 1 MeV(Si) fluences, neutron spectra, total exposures and dose rates were predicted with good agreement by n, {gamma} photon transport codes. (author). 12 refs., 2 figs., 1 tab.

  17. Cavitation in dielectric fluid in inhomogeneous pulsed electric field

    CERN Document Server

    Shneider, M N

    2013-01-01

    This paper proposes a method for studying the early stages of the cavitation development in arbitrary, non-stationary conditions. This method is based on the comparison of the results of calculations in the framework of a theoretical model of the liquid dielectrics motion in a strong non-uniform electric field and experiments with controlled parameters. This approach allows us to find the critical negative pressure, at which cavitation begins to develop, and to determine the values of the constants in the classical models of cavitation.

  18. Terahertz field enhancement via coherent superposition of the pulse sequences after a single optical-rectification crystal

    Science.gov (United States)

    Sajadi, Mohsen; Wolf, Martin; Kampfrath, Tobias

    2014-03-01

    Terahertz electromagnetic pulses are frequently generated by optical rectification of femtosecond laser pulses. In many cases, the efficiency of this process is known to saturate with increasing intensity of the generation beam because of two-photon absorption. Here, we demonstrate two routes to reduce this effect in ZnTe(110) crystals and enhance efficiency, namely, by (i) recycling the generation pulses and by (ii) splitting each generation pulse into two pulses before pumping the crystal. In both methods, the second pulse arrives ˜1 ns after the first one, sufficiently long for optically generated carriers to relax. Enhancement is achieved by coherently superimposing the two resulting terahertz fields.

  19. Terahertz field enhancement via coherent superposition of the pulse sequences after a single optical-rectification crystal

    Energy Technology Data Exchange (ETDEWEB)

    Sajadi, Mohsen, E-mail: sajadi@fhi-berlin.mpg.de; Wolf, Martin; Kampfrath, Tobias [Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin (Germany)

    2014-03-03

    Terahertz electromagnetic pulses are frequently generated by optical rectification of femtosecond laser pulses. In many cases, the efficiency of this process is known to saturate with increasing intensity of the generation beam because of two-photon absorption. Here, we demonstrate two routes to reduce this effect in ZnTe(110) crystals and enhance efficiency, namely, by (i) recycling the generation pulses and by (ii) splitting each generation pulse into two pulses before pumping the crystal. In both methods, the second pulse arrives ∼1 ns after the first one, sufficiently long for optically generated carriers to relax. Enhancement is achieved by coherently superimposing the two resulting terahertz fields.

  20. Simulation and experiments of Stacks of High Temperature Superconducting Coated Conductors Magnetized by Pulsed Field Magnetization with Multi-Pulse Technique

    CERN Document Server

    Zou, Shengnan; Baskys, A; Patel, A; Grilli, Francesco; Glowacki, B A

    2016-01-01

    High temperature superconducting (HTS) bulks or stacks of coated conductors (CCs) can be magnetized to become trapped field magnets (TFMs). The magnetic fields of such TFMs can break the limitation of conventional magnets (<2 T), so they show potential for improving the performance of many electrical applications that use permanent magnets like rotating machines. Towards practical or commercial use of TFMs, effective in situ magnetization is one of the key issues. The pulsed field magnetization (PFM) is among the most promising magnetization methods in virtue of its compactness, mobility and low cost. However, due to the heat generation during the magnetization, the trapped field and flux acquired by PFM usually cannot achieve the full potential of a sample (acquired by the field cooling or zero field cooling method). The multi-pulse technique was found to effectively improve the trapped field by PFM in practice. In this work, a systematic study on the PFM with successive pulses is presented. A 2D electrom...

  1. A high-field pulsed magnet system for x-ray scattering studies in Voigt geometry

    CERN Document Server

    Islam, Zahirul; Ruff, Jacob P C; Das, Ritesh K; Trakhtenberg, Emil; Nojiri, Hiroyuki; Narumi, Yasuo; Canfield, Paul C

    2011-01-01

    We present a new pulsed-magnet system that enables x-ray single-crystal diffraction in addition to powder and spectroscopic studies in Voigt geometry. The apparatus consists of a large-bore solenoid, cooled by liquid nitrogen. A second independent closed-cycle cryostat is used for cooling samples near liquid helium temperatures. Pulsed magnetic fields up to ~30 T with a minimum of ~6 ms in total duration are generated by discharging a 40 kJ capacitor bank into the magnet coil. The unique characteristic of this instrument is the preservation of maximum scattering angle (~23.6 deg.) through the magnet bore by virtue of a novel double-funnel insert. This instrument would facilitate x-ray diffraction and spectroscopic studies that are impractical, if not impossible, to perform using conventional split-pair magnets and offers a practical solution for preserving optical access in future higher-field pulsed magnets.

  2. Pulsed high field magnets. An efficient way of shaping laser accelerated proton beams for application

    Energy Technology Data Exchange (ETDEWEB)

    Kroll, Florian; Schramm, Ulrich [Helmholtz-Zentrum Dresden - Rossendorf, 01328 Dresden (Germany); Technische Universitaet Dresden, 01062 Dresden (Germany); Bagnoud, Vincent; Blazevic, Abel; Busold, Simon [GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Helmholtz Institut Jena, 07734 Jena (Germany); Brabetz, Christian; Schumacher, Dennis [GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Deppert, Oliver; Jahn, Diana; Roth, Markus [Technische Universitaet Darmstadt, 64289 Darmstadt (Germany); Karsch, Leonhard; Masood, Umar [OncoRay-National Center for Radiation Research in Oncology, TU Dresden, 01307 Dresden (Germany); Kraft, Stephan [Helmholtz-Zentrum Dresden - Rossendorf, 01328 Dresden (Germany)

    2015-07-01

    Compact laser-driven proton accelerators are a potential alternative to complex, expensive conventional accelerators, enabling unique beam properties, like ultra-high pulse dose. Nevertheless, they still require substantial development in reliable beam generation and transport. We present experimental studies on capture, shape and transport of laser and conventionally accelerated protons via pulsed high-field magnets. These magnets, common research tools in the fields of solid state physics, have been adapted to meet the demands of laser acceleration experiments.Our work distinctively shows that pulsed magnet technology makes laser acceleration more suitable for application and can facilitate compact and efficient accelerators, e.g. for material research as well as medical and biological purposes.

  3. Control of predators in industrial scale microalgae cultures with Pulsed Electric Fields.

    Science.gov (United States)

    Rego, D; Redondo, L M; Geraldes, V; Costa, L; Navalho, J; Pereira, M T

    2015-06-01

    This work describes the utilization of Pulsed Electric Fields to control the protozoan contamination of a microalgae culture, in an industrial 2.7 m(3) microalgae photobioreactor. The contaminated culture was treated with Pulsed Electric Fields, PEF, for 6h with an average of 900 V/cm, 65 μs pulses of 50 Hz. Working with recirculation, all the culture was uniformly exposed to the PEF throughout the assay. The development of the microalgae and protozoan populations was followed and the results showed that PEF is effective on the selective elimination of protozoa from microalgae cultures, inflicting on the protozoa growth halt, death or cell rupture, without affecting microalgae productivity. Specifically, the results show a reduction of the active protozoan population of 87% after 6h treatment and 100% after few days of normal cultivation regime. At the same time, microalgae growth rate remained unaffected.

  4. Ultra-fast ballistic magnetization reversal triggered by a single magnetic field pulse

    Energy Technology Data Exchange (ETDEWEB)

    Horley, Paul P; Gonzalez Hernandez, Jesus [Centro de Investigacion en Materiales Avanzados S.C., Chihuahua/Monterrey, Av. Miguel de Cervantes 120, 31109 Chihuahua, Chihuahua (Mexico); Vieira, Vitor R; Dugaev, Vitalii K [Centro de Fisica das Interaccoes Fundamentais, Instituto Superior Tecnico, Universidade Tecnica de Lisboa, Avenida Rovisco Pais, 1049-001 Lisbon (Portugal); Gorley, Peter [Department of Physics, Yuri Fedkovych Chernivtsi National University, 2 Kotsyubynsky Street, 58012 Chernivtsi (Ukraine); Barnas, Jozef, E-mail: paul.horley@cimav.edu.m [Institute of Molecular Physics, Polish Academy of Sciences, ul. Smoluchowskiego 17, 60-179 Poznan (Poland)

    2009-12-21

    Performance of devices such as magnetic random access memories crucially depends on magnetic switching time. By numerical simulations we show that ultra-fast (in the sub-nanosecond range) magnetic reversal in nanoparticles can be achieved with a single pulse of magnetic field oriented at some specific angles with respect to the magnetic moment. These angles form the areas of ballistic reversal (with no magnetization ringing). We show that the size of these areas increases with decreasing pulse duration, which allows reaching of the sub-nanosecond reversal for a pulse duration of the order of dozen(s) of ps. When changing the magnetic field, the areas of ballistic reversal move along the equator of the unitary sphere, and eventually merge with each other. For appropriate choice of the azimuthal angle, one can reach magnetic reversal along a trajectory located in or out of the easy plane.

  5. Strong-field ionization inducing multi-electron-hole coherence probed by attosecond pulses

    CERN Document Server

    Zhao, Jing; Zhao, Zengxiu

    2015-01-01

    We propose a new scenario to apply IR-pump-XUV-probe schemes to resolving strong field ionization induced and attosecond pulse driven electron-hole dynamics and coherence in real time. The coherent driving of both the infrared laser and the attoscond pulse correlates the dynamics of the core-hole and the valence-hole which leads to the otherwise forbidden absorption and emission of XUV photon. An analytical model is developed based on the strong-field approximation by taking into account of the essential multielectron configurations. The emission spectra from the core-valence transition and the core-hole recombination are found modulating strongly as functions of the time delay between the two pulses, which provides a unique insight into the instantaneous ionization and the interplay of the multi-electron-hole coherence.

  6. The effect of high voltage, high frequency pulsed electric field on slain ovine cortical bone.

    Science.gov (United States)

    Asgarifar, Hajarossadat; Oloyede, Adekunle; Zare, Firuz

    2014-04-01

    High power, high frequency pulsed electric fields known as pulsed power (PP) has been applied recently in biology and medicine. However, little attention has been paid to investigate the application of pulse power in musculoskeletal system and its possible effect on functional behavior and biomechanical properties of bone tissue. This paper presents the first research investigating whether or not PP can be applied safely on bone tissue as a stimuli and what will be the possible effect of these signals on the characteristics of cortical bone by comparing the mechanical properties of this type of bone pre and post expose to PP and in comparison with the control samples. A positive buck-boost converter was applied to generate adjustable high voltage, high frequency pulses (up to 500 V and 10 kHz). The functional behavior of bone in response to pulse power excitation was elucidated by applying compressive loading until failure. The stiffness, failure stress (strength) and the total fracture energy (bone toughness) were determined as a measure of the main bone characteristics. Furthermore, an ultrasonic technique was applied to determine and comprise bone elasticity before and after pulse power stimulation. The elastic property of cortical bone samples appeared to remain unchanged following exposure to pulse power excitation for all three orthogonal directions obtained from ultrasonic technique and similarly from the compression test. Nevertheless, the compressive strength and toughness of bone samples were increased when they were exposed to 66 h of high power pulsed electromagnetic field compared to the control samples. As the toughness and the strength of the cortical bone tissue are directly associated with the quality and integrity of the collagen matrix whereas its stiffness is primarily related to bone mineral content these overall results may address that although, the pulse power stimulation can influence the arrangement or the quality of the collagen network

  7. All-optical control of unipolar pulse generation in spatially extended arrays of optical oscillators with nonlinear field coupling

    CERN Document Server

    Pakhomov, A V; Babushkin, I V; Arkhipov, M V; Tolmachev, Yu A; Rosanov, N N

    2016-01-01

    We study the optical response of a resonant medium possessing the nonlinear coupling to external field under excitation by few-cycle pump pulses. A theoretical approach is developed, allowing to analyze unipolar half-cycle pulse generation in such a geometry. Our approach is applicable for the arbitrary coupling functions as well as arbitrarily curved pump pulse wavefronts and defines a general framework to produce unipolar pulses of desired form.

  8. Electrosensitization assists cell ablation by nanosecond pulsed electric field in 3D cultures.

    Science.gov (United States)

    Muratori, Claudia; Pakhomov, Andrei G; Xiao, Shu; Pakhomova, Olga N

    2016-03-18

    Previous studies reported a delayed increase of sensitivity to electroporation (termed "electrosensitization") in mammalian cells that had been subjected to electroporation. Electrosensitization facilitated membrane permeabilization and reduced survival in cell suspensions when the electric pulse treatments were split in fractions. The present study was aimed to visualize the effect of sensitization and establish its utility for cell ablation. We used KLN 205 squamous carcinoma cells embedded in an agarose gel and cell spheroids in Matrigel. A local ablation was created by a train of 200 to 600 of 300-ns pulses (50 Hz, 300-600 V) delivered by a two-needle probe with 1-mm inter-electrode distance. In order to facilitate ablation by engaging electrosensitization, the train was split in two identical fractions applied with a 2- to 480-s interval. At 400-600 V (2.9-4.3 kV/cm), the split-dose treatments increased the ablation volume and cell death up to 2-3-fold compared to single-train treatments. Under the conditions tested, the maximum enhancement of ablation was achieved when two fractions were separated by 100 s. The results suggest that engaging electrosensitization may assist in vivo cancer ablation by reducing the voltage or number of pulses required, or by enabling larger inter-electrode distances without losing the ablation efficiency.

  9. Improved convection compensating pulsed field gradient spin-echo and stimulated-echo methods.

    Science.gov (United States)

    Sørland, G H; Seland, J G; Krane, J; Anthonsen, H W

    2000-02-01

    The need for convection compensating methods in NMR has been manifested through an increasing number of publications related to the subject over the past few years (J. Magn. Reson. 125, 372 (1997); 132, 13 (1998); 131, 126 (1998); 118, 50 (1996); 133, 379 (1998)). When performing measurements at elevated temperature, small convection currents may give rise to erroneous values of the diffusion coefficient. In work with high resolution NMR spectroscopy, the application of magnetic field gradients also introduces an eddy-current magnetic field which may result in errors in phase and baseline in the FFT-spectra. The eddy current field has been greatly suppressed by the application of bipolar magnetic field gradients. However, when introducing bipolar magnetic field gradients, the pulse sequence is lengthened significantly. This has recently been pointed out as a major drawback because of the loss of coherence and of NMR-signal due to transverse relaxation processes. Here we present modified convection compensating pulsed field gradient double spin echo and double stimulated echo sequences which suppress the eddy-current magnetic field without increasing the duration of the pulse sequences.

  10. Evaluation and interpretation of bubble size distributions in pulsed megasonic fields

    Science.gov (United States)

    Hauptmann, M.; Struyf, H.; De Gendt, S.; Glorieux, C.; Brems, S.

    2013-05-01

    The occurrence of acoustic cavitation is incorporating a multitude of interdependent effects that strongly depend on the bubble size. Therefore, bubble size control would be beneficial for biological and industrial processes that rely on acoustic cavitation. A pulsed acoustic field can result in bubble size control and the repeated dissolution and reactivation ("recycling") of potentially active bubbles. As a consequence, a pulsed field can strongly enhance cavitation activity. In this paper, we present a modified methodology for the evaluation of the active bubble size distribution by means of a combination of cavitation noise measurements and ultrasonic pulsing. The key component of this modified methodology is the definition of an upper size limit, below which bubbles—in between subsequent pulses—have to dissolve, in order to be sustainably recycled. This upper limit makes it possible to explain and link the enhancement of cavitation activity to a bubble size distribution. The experimentally determined bubble size distributions for different power densities are interpreted in the frame of numerical calculations of the oscillatory responses of the bubbles to the intermittent driving sound field. The distributions are found to be shaped by the size dependent interplay between bubble pulsations, rectified diffusion, coalescence, and the development of parametrically amplified shape instabilities. Also, a phenomenological reactivation-deactivation model is proposed to explain and quantify the observed enhancement of cavitation activity under pulsed, with respect to continuous sonication. In this model, the pulse-duration determines the magnitude of the reactivation of partially dissolved bubbles and the deactivation of activated bubbles by coalescence. It is shown that the subsequent recycling of previously active bubbles leads to an accumulation of cavitation activity, which saturates after a certain number of pulses. The model is fitted to the experimental

  11. Isolated attosecond pulses generation from coherent superposition state of helium ion in static electric fields and spatial nonhomogeneous fields

    Science.gov (United States)

    Liu, Hao; Zhang, Zhengzhong; Wu, Yangjiang; Jiang, Shicheng; Yu, Chao

    2016-09-01

    We present a systematic study of high-order harmonic generation (HHG) from helium ion with the initial state prepared as a coherent superposition of electronic ground state and an excited state. As a result, the conversion efficiency of the harmonic spectrum is significantly enhanced. When we add a static electric field in fundamental field, the supercontinuum region of the harmonic spectrum is distinctly extended and an isolated 100 as pulse can be generated. Moreover, we use a spatial nonhomogeneous field to increase the cutoff energy in high-order harmonic generation spectrum, which can be extended to about 700 eV, and an isolated 50 as pulse can be obtained directly by the superposition of the supercontinuum harmonics.

  12. Cost analysis of commercial pasteurization of orange juice by pulsed electric fields

    Science.gov (United States)

    The cost of pulsed electric field (PEF) pasteurization of orange juice was estimated. The cost analysis was based on processing conditions that met the US FDA (5 log reduction) requirement for fruit juice pasteurization and that achieved a 2 month microbial shelf-life. PEF-treated samples processed ...

  13. Effect of pulsed electric field treatment on hot-boned muscles of different potential tenderness.

    Science.gov (United States)

    Suwandy, Via; Carne, Alan; van de Ven, Remy; Bekhit, Alaa El-Din A; Hopkins, David L

    2015-07-01

    In this study, the effect of pulsed electric field (PEF) treatment and ageing on the quality of beef M. longissimus lumborum (LL) and M. semimembranosus (SM) muscles was evaluated, including the tenderness, water loss and post-mortem proteolysis. Muscles were obtained from 12 steers (6 steers for each muscle), removed from the carcasses 4 hour postmortem and were treated with pulsed electric field within 2h. Six different pulsed electric field intensities (voltages of 5 and 10 kV × frequencies of 20, 50 and 90 Hz) plus a control were applied to each muscle to determine the optimum treatment conditions. Beef LL was found to get tougher with increasing treatment frequency whereas beef SM muscle was found to have up to 21.6% reduction in the shear force with pulsed electric field treatment. Post-mortem proteolysis showed an increase in both troponin and desmin degradation in beef LL treated with low intensity PEF treatment (20 Hz) compared to non-treated control samples.

  14. Conductive plastic film electrodes for Pulsed Electric Field (PEF) treatment : A proof of principle

    NARCIS (Netherlands)

    Roodenburg, B.; Haan, S.W.H. de; Boxtel, L.B.J. van; Hatt, V.; Wouters, P.C.; Coronel, P.; Ferreira, J.A.

    2010-01-01

    Nowadays Pulsed Electric Field (PEF) treatment of food needs to be performed prior to packaging, either hygienic or aseptic packaging is necessary. New techniques for PEF treatment after packaging can be considered when plastic conductive (film) electrodes can be integrated within the package, so th

  15. Microstructure refinement of AZ91D alloy solidified with pulsed magnetic field

    Institute of Scientific and Technical Information of China (English)

    WANG Bin; YANG Yuan-sheng; ZHOU Ji-xue; TONG Wen-hui

    2008-01-01

    The effects of pulsed magnetic field on the solidified microstructure of an AZ91D magnesium alloy were investigated. The experimental results show that the remarkable microstructural refinement is achieved when the pulsed magnetic field is applied in the solidification of AZ91D alloy. The average grain size of the as-cast microstructure of AZ91D alloy is refined to 104μm. Besides the grain refinement, the morphology of the primary α-Mg is changed from dendritic to rosette, then to globular shape with changing the parameters of the pulsed magnetic field. The pulsed magnetic field causes melt convection during solidification, which makes the temperature of the whole melt homogenized, and produces an undercooling zone in front of the liquid/solid interface by the magnetic pressure, which makes the nucleation rate increased and big dendrites prohibited. In addition, primary α-Mg dendrites break into fine crystals, resulting in a refined solidification structure of the AZ91D alloy. The Joule heat effect induced in the melt also strengthens the grain refinement effect and spheroidization of dendrite arms.

  16. Transcranial low voltage pulsed electromagnetic fields in patients with treatment-resistant depression

    DEFF Research Database (Denmark)

    Martiny, Klaus Per Juul; Lunde, Marianne; Bech, Per

    2010-01-01

    of a new principle using low-intensity transcranially applied pulsed electromagnetic fields (T-PEMF) in combination with antidepressants in patients with treatment-resistant depression. METHODS: This was a sham-controlled double-blind study comparing 5 weeks of active or sham T-PEMF in patients...

  17. Trial Application of Pulse-Field Magnetization to Magnetically Levitated Conveyor System

    Directory of Open Access Journals (Sweden)

    Yoshihito Miyatake

    2012-01-01

    Full Text Available Magnetically levitated conveyor system using superconductors is discussed. The system is composed of a levitated conveyor, magnetic rails, a linear induction motor, and some power supplies. In the paper, pulse-field magnetization is applied to the system. Then, the levitation height and the dynamics of the conveyor are controlled. The static and dynamic characteristics of the levitated conveyor are discussed.

  18. Spin-orbit interaction in chiral carbon nanotubes probed in pulsed magnetic fields

    NARCIS (Netherlands)

    Jhang, S.H.; Marganska, M.; Skourski, Y.; Preusche, D.; Witkamp, B.; Grifoni, M.; Van der Zant, H.; Wosnitza, J.; Strunk, C.

    2010-01-01

    The magnetoconductance of an open carbon nanotube (CNT)-quantum wire was measured in pulsed magnetic fields. At low temperatures, we find a peculiar split magnetoconductance peak close to the chargeneutrality point. Our analysis of the data reveals that this splitting is intimately connected to the

  19. REMANENCE MEASUREMENTS ON INDIVIDUAL MAGNETOTACTIC BACTERIA USING A PULSED MAGNETIC-FIELD

    NARCIS (Netherlands)

    PENNINGA, Ietje; Waard , de Hendrik; MOSKOWITZ, BM; BAZYLINSKI, DA; FRANKEL, RB

    1995-01-01

    We describe pulsed-magnetic-field remanence measurements of individual, killed, undisrupted cells of three different types of magnetotactic bacteria. The measurement technique involved the observation of aligned, individual magnetotactic bacteria with a light microscope as they were subjected to mag

  20. Conductive plastic film electrodes for Pulsed Electric Field (PEF) treatment : A proof of principle

    NARCIS (Netherlands)

    Roodenburg, B.; Haan, S.W.H. de; Boxtel, L.B.J. van; Hatt, V.; Wouters, P.C.; Coronel, P.; Ferreira, J.A.

    2010-01-01

    Nowadays Pulsed Electric Field (PEF) treatment of food needs to be performed prior to packaging, either hygienic or aseptic packaging is necessary. New techniques for PEF treatment after packaging can be considered when plastic conductive (film) electrodes can be integrated within the package, so

  1. Pulsed Electric Field for protein release of the microalgae Chlorella vulgaris and Neochloris oleoabundans

    NARCIS (Netherlands)

    Lam, 't Gerard; Postma, P.R.; Fernandes, D.A.; Timmermans, R.A.H.; Vermuë, M.H.; Barbosa, M.J.; Eppink, M.H.; Wijffels, R.H.; Olivieri, G.

    2017-01-01

    Pulsed Electric Field (PEF) is currently discussed as promising technology for mild and scalable cell disintegration of microalgae. In this study Chlorella vulgaris and Neochloris oleoabundans have been subjected to batch and continuous PEF treatments under a wide range of operating conditions

  2. [Effect of pulsed electromagnetic field on orthodontic tooth movement through transmission electromicroscopy].

    Science.gov (United States)

    Chen, Q

    1991-01-01

    This experiment is to observe the effect of pulsed electromagnetic field (PEMF) on orthodontic tooth movement of guinea pigs through transmission electron microscope (TEM). 14-days observations indicate that PEMF could accelerate the rate of orthodontic tooth movement as a result of the increase in quantity of active cell without changing the ultrastructures of cells and have no unfavorable effects on periodontal tissues.

  3. Field and laboratory simulations of storm water pulses: Behavioural avoidance by marine epifauna

    Energy Technology Data Exchange (ETDEWEB)

    Roberts, David A. [School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052 (Australia)], E-mail: d.roberts@student.unsw.edu.au; Johnston, Emma L.; Mueller, Stefanie; Poore, Alistair G.B. [School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052 (Australia)

    2008-03-15

    Epifaunal communities associated with macroalgae were exposed to storm water pulses using a custom made irrigation system. Treatments included Millipore freshwater, freshwater spiked with trace metals and seawater controls to allow for the relative importance of freshwater inundation, trace metals and increased flow to be determined. Experimental pulses created conditions similar to those that occur following real storm water events. Brief storm water pulses reduced the abundance of amphipods and gastropods. Freshwater was the causative agent as there were no additional effects of trace metals on the assemblages. Laboratory assays indicated that neither direct nor latent mortality was likely following experimental pulses and that epifauna readily avoid storm water. Indirect effects upon epifauna through salinity-induced changes to algal habitats were not found in field recolonisation experiments. Results demonstrate the importance of examining the effects of pulsed contaminants under realistic exposure conditions and the need to consider ecologically relevant endpoints. - Brief storm water pulses trigger avoidance response in mobile epifauna due to the inundation of freshwater.

  4. Numerical simulation of temperature field in K9 glass irradiated by ultraviolet pulse laser

    Science.gov (United States)

    Wang, Xi; Fang, Xiaodong

    2015-10-01

    The optical component of photoelectric system was easy to be damaged by irradiation of high power pulse laser, so the effect of high power pulse laser irradiation on K9 glass was researched. A thermodynamic model of K9 glass irradiated by ultraviolet pulse laser was established using the finite element software ANSYS. The article analyzed some key problems in simulation process of ultraviolet pulse laser damage of K9 glass based on ANSYS from the finite element models foundation, meshing, loading of pulse laser, setting initial conditions and boundary conditions and setting the thermal physical parameters of material. The finite element method (FEM) model was established and a numerical analysis was performed to calculate temperature field in K9 glass irradiated by ultraviolet pulse laser. The simulation results showed that the temperature of irradiation area exceeded the melting point of K9 glass, while the incident laser energy was low. The thermal damage dominated in the damage mechanism of K9 glass, the melting phenomenon should be much more distinct.

  5. Coherent addition of gratings for chirped-pulse-amplified lasers based on near-field and far-field measurements

    Institute of Scientific and Technical Information of China (English)

    Yuchuan Yang; Hui Luo; Xiao Wang; Fuquan Li; Xiaojun Huang; Bin Feng; Feng Jing

    2011-01-01

    @@ The development of phased-array grating compressor is a crucial issue for high-energy, ultra-short pulse petawatt-class lasers.Almost all systems have adopted a tiled-grating approach to meet the size require-ments for the compression gratings.We present a computer-control test system utilizing near-field interfer-ence and far-field focusing capable of monitoring and fast correcting tiled errors of the grating compressor.In this system, the tilt/tip errors between the two gratings are determined by the Fourier transform (FT)of the individual inteiference fringe, and the piston errors are determined by the ratio of the two primary peaks formed in the far-field pattern as a function of the piston difference.Monochromatic grating phasing is achieved experimentally and pulse compression is demonstrated with a tiled grating system.%The development of phased-array grating compressor is a crucial issue for high-energy, ultra-short pulse petawatt-class lasers. Almost all systems have adopted a tiled-grating approach to meet the size requirements for the compression gratings. We present a computer-control test system utilizing near-field interference and far-field focusing capable of monitoring and fast correcting tiled errors of the grating compressor.In this system, the tilt/tip errors between the two gratings are determined by the Fourier transform (FT)of the individual inter ference fringe, and the piston errors are determined by the ratio of the two primary peaks formed in the far-field pattern as a function of the piston difference. Monochromatic grating phasing is achieved experimentally and pulse compression is demonstrated with a tiled grating system.

  6. Charge and spin current oscillations in a tunnel junction induced by magnetic field pulses

    Science.gov (United States)

    Dartora, C. A.; Nobrega, K. Z.; Cabrera, G. G.

    2016-08-01

    Usually, charge and spin transport properties in tunnel junctions are studied in the DC bias regime and/or in the adiabatic regime of time-varying magnetic fields. In this letter, the temporal dynamics of charge and spin currents in a tunnel junction induced by pulsed magnetic fields is considered. At low bias voltages, energy and momentum of the conduction electrons are nearly conserved in the tunneling process, leading to the description of the junction as a spin-1/2 fermionic system coupled to time-varying magnetic fields. Under the influence of pulsed magnetic fields, charge and spin current can flow across the tunnel junction, displaying oscillatory behavior, even in the absence of DC bias voltage. A type of spin capacitance function, in close analogy to electric capacitance, is predicted.

  7. Carrier field shock formation of long wavelength femtosecond pulses in dispersive media

    CERN Document Server

    Panagiotopoulos, Paris; Kolesik, Miroslav; Moloney, Jerome V

    2015-01-01

    We numerically demonstrate the formation of carrier field shocks in various dispersive media for a wide variety of input conditions using two different electric field propagation models. In addition, an investigation of the impact of numerous physical effects on carrier wave shock is performed. It is shown that in many cases a field shock is essentially unavoidable and therefore extremely important in the propagation of intense long wavelength pulses in weakly dispersive nonlinear media such as noble gases, air, and single-crystal diamond. The results presented here are expected to have a significant impact in the field of ultrashort nonlinear optics, attosecond pulse generation, and wavepacket synthesis where the use of mid-IR wavelengths is becoming increasingly more important.

  8. Electric field simulation and measurement of a pulse line ion accelerator

    Institute of Scientific and Technical Information of China (English)

    SHEN Xiao-Kang; ZHANG Zi-Min; CAO Shu-Chun; ZHAO Hong-Wei; WANG Bo; SHEN Xiao-Li; ZHAO Quan-Tang; LIU Ming; JING Yi

    2012-01-01

    An oil dielectric helical pulse line to demonstrate the principles of a Pulse Line Ion Accelerator (PL1A) has been designed and fabricated.The simulation of the axial electric field of an accelerator with CST code has been completed and the simulation results show complete agreement with the theoretical calculations.To fully understand the real value of the electric field excited from the helical line in PLIA,an optical electric integrated electric field measurement system was adopted.The measurement result shows that the real magnitude of axial electric field is smaller than that calculated,probably due to the actual pitch of the resister column which is much less than that of helix.

  9. Exploring the Effects of Pulsed Electric Field Processing Parameters on Polyacetylene Extraction from Carrot Slices

    Directory of Open Access Journals (Sweden)

    Ingrid Aguiló-Aguayo

    2015-03-01

    Full Text Available The effects of various pulsed electric field (PEF parameters on the extraction of polyacetylenes from carrot slices were investigated. Optimised conditions with regard to electric field strength (1–4 kV/cm, number of pulses (100–1500, pulse frequency (10–200 Hz and pulse width (10–30 μs were identified using response surface methodology (RSM to maximise the extraction of falcarinol (FaOH, falcarindiol (FaDOH and falcarindiol-3-acetate (FaDOAc from carrot slices. Data obtained from RSM and experiments fitted significantly (p < 0.0001 the proposed second-order response functions with high regression coefficients (R2 ranging from 0.82 to 0.75. Maximal FaOH (188%, FaDOH (164.9% and FaDOAc (166.8% levels relative to untreated samples were obtained from carrot slices after applying PEF treatments at 4 kV/cm with 100 number of pulses of 10 μs at 10 Hz. The predicted values from the developed quadratic polynomial equation were in close agreement with the actual experimental values with low average mean deviations (E% ranging from 0.68% to 3.58%.

  10. Exploring the effects of pulsed electric field processing parameters on polyacetylene extraction from carrot slices.

    Science.gov (United States)

    Aguiló-Aguayo, Ingrid; Abreu, Corina; Hossain, Mohammad B; Altisent, Rosa; Brunton, Nigel; Viñas, Inmaculada; Rai, Dilip K

    2015-03-02

    The effects of various pulsed electric field (PEF) parameters on the extraction of polyacetylenes from carrot slices were investigated. Optimised conditions with regard to electric field strength (1-4 kV/cm), number of pulses (100-1500), pulse frequency (10-200 Hz) and pulse width (10-30 μs) were identified using response surface methodology (RSM) to maximise the extraction of falcarinol (FaOH), falcarindiol (FaDOH) and falcarindiol-3-acetate (FaDOAc) from carrot slices. Data obtained from RSM and experiments fitted significantly (p < 0.0001) the proposed second-order response functions with high regression coefficients (R2) ranging from 0.82 to 0.75. Maximal FaOH (188%), FaDOH (164.9%) and FaDOAc (166.8%) levels relative to untreated samples were obtained from carrot slices after applying PEF treatments at 4 kV/cm with 100 number of pulses of 10 μs at 10 Hz. The predicted values from the developed quadratic polynomial equation were in close agreement with the actual experimental values with low average mean deviations (E%) ranging from 0.68% to 3.58%.

  11. Compact short-pulse laser for near-field range-gated imaging

    Science.gov (United States)

    Zutavern, Fred J.; Helgeson, Wesley D.; Loubriel, Guillermo M.; Yates, George J.; Gallegos, Robert A.; McDonald, Thomas E., Jr.

    1997-05-01

    This paper describes a compact laser, which produces high power, wide-angle emission for a near-field, range-gated, imaging system. The optical pulses are produced by a 100 element laser diode array (LDA) which is pulsed with a GaAs, photoconductive semiconductor switch (PCSS). The LDA generates 100 ps long, gain-switched, optical pulses at 904 nm when it is driven with 3 ns, 400 A, electrical pulses from a high gain PCSS. Gain switching is facilitated with this many lasers by using a low impedance circuit to drive an array of lasers, which are connected electrically in series. The total optical energy produced per pulse is 100 microjoules corresponding to a total peak power of 100 kW. The entire laser system, including prime power (a nine volt battery), pulse charging, PCSS, and LDA, is the size of a small, hand-held flashlight, System lifetime, which is presently limited by the high gain PCSS, is an active area of research and development. Present limitations and potential improvements will be discussed. The complete range-gated imaging system is based on complementary technologies: high speed optical gating with intensified charge coupled devices (ICCD) developed at Los Alamos National Laboratory and high gain, PCSS-driven LDAs developed at Sandia National Laboratories. The system is designed for use in highly scattering media such as turbid water or extremely dense fog or smoke. The short optical pulses from the laser and high speed gating of the ICCD are synchronized to eliminate the back-scattered light from outside the depth of the field of view (FOV) which may be as short as a few centimeters. A high speed photodiode can be used to trigger the intensifier gate and set the range-gated FOV precisely on the target. The ICCD and other aspects of the imaging system are discussed in a separate paper.

  12. Investigation of a direct effect of nanosecond pulse electric fields on mitochondria

    Science.gov (United States)

    Estlack, Larry E.; Roth, Caleb C.; Cerna, Cesario Z.; Wilmink, Gerald J.; Ibey, Bennett L.

    2014-03-01

    The unique cellular response to nanosecond pulsed electric field (nsPEF) exposure, as compared to longer pulse exposure, has been theorized to be due to permeabilization of intracellular organelles including the mitochondria. In this investigation, we utilized a high-throughput oxygen and pH sensing system (Seahorse® XF24 extracellular flux analyzer) to assess the mitochondrial activity of Jurkat and U937 cells after nsPEF. The XF Analyzer uses a transient micro-chamber of only a few μL in specialized cell culture micro-plates to enable oxygen consumption rate (OCR) and extracellular acidification rate (ECAR) to be monitored in real-time. We found that for nsPEF exposures of 10 pulses at 10-ns pulse width and at 50 kV/cm e-field, we were able to cause an increase in OCR in both U937 and Jurkat cells. We also found that high pulse numbers (>100) caused a significant decrease in OCR. Higher amplitude 150 kV/cm exposures had no effect on U937 cells and yet they had a deleterious effect on Jurkat cells, matching previously published 24 hour survival data. These results suggest that the exposures were modulating metabolic activity in cells possibly due to direct effects on the mitochondria themselves. To validate this hypothesis, we isolated mitochondria from U937 cells and exposed them similarly and found no significant change in metabolic activity for any pulse number. In a final experiment, we removed calcium from the buffer solution that the cells were exposed in and found that no significant enhancement in metabolic activity was observed. These results suggest that direct permeabilization of the mitochondria is unlikely a primary effect of nsPEF exposure and calcium-mediated intracellular pathway activation is likely responsible for observed pulse-induced mitochondrial effects.

  13. Investigating membrane nanoporation induced by bipolar pulsed electric fields via second harmonic generation

    Science.gov (United States)

    Moen, E. K.; Ibey, B. L.; Beier, H. T.; Armani, A. M.

    2016-09-01

    Electric pulses have become an effective tool for transporting cargo (DNA, drugs, etc.) across cell membranes. This enhanced transport is believed to occur through temporary pores formed in the plasma membrane. Traditionally, millisecond duration, monopolar (MP) pulses are used for electroporation, but bipolar (BP) pulses have proven equally effective as MP pulses with the added advantage of less cytotoxicity. With the goal of further reducing cytotoxic effects and inducing non-thermal, intra-cellular effects, researchers began investigating reduced pulse durations, pushing into the nanosecond regime. Cells exposed to these MP, nanosecond pulsed electric fields (nsPEFs) have shown increased repairable membrane permeability and selective channel activation. However, attempts to improve this further by moving to the BP pulse regime has proven unsuccessful. In the present work, we use second harmonic generation imaging to explore the structural effects of bipolar nsPEFs on the plasma membrane. By varying the temporal spacing between the pulse phases over several orders of magnitude and comparing the response to a single MP case, we systematically examine the disparity in cellular response. Our circuit-based model predicts that, as the temporal spacing increases several orders of magnitude, nanoporation increases and eventually exceeds the MP case. On the whole, our experimental data agree with this assertion; however, a detailed analysis of the data sets demonstrates that biological processes may play a larger role in the observed response than previously thought, dominating the effect for temporal spacing up to 5 μs. These findings could ultimately lead to understanding the biophysical mechanism underlying all electroporation.

  14. Pulsed ultrasound associated with gold nanoparticle gel reduces oxidative stress parameters and expression of pro-inflammatory molecules in an animal model of muscle injury

    Directory of Open Access Journals (Sweden)

    Victor Eduardo G

    2012-03-01

    Full Text Available Abstract Background Nanogold has been investigated in a wide variety of biomedical applications because of the anti-inflammatory properties. The purpose of this study was to evaluate the effects of TPU (Therapeutic Pulsed Ultrasound with gold nanoparticles (GNP on oxidative stress parameters and the expression of pro-inflammatory molecules after traumatic muscle injury. Materials and methods Animals were divided in nine groups: sham (uninjured muscle; muscle injury without treatment; muscle injury + DMSO; muscle injury + GNP; muscle injury + DMSO + GNP; muscle injury + TPU; muscle injury + TPU + DMSO; muscle injury + TPU + GNP; muscle injury + TPU + DMSO + GNP. The ROS production was determined by concentration of superoxide anion, modulation of antioxidant defenses was determined by the activity of superoxide dismutase, catalase and glutathione peroxidase enzymes, oxidative damage determined by formation of thiobarbituric acid-reactive substance and protein carbonyls. The levels of interleukin-1β (IL-1β and tumor necrosis factor-α (TNF-α were measured as inflammatory parameters. Results Compared to muscle injury without treatment group, the muscle injury + TPU + DMSO + GNP gel group promoted a significant decrease in superoxide anion production and lipid peroxidation levels (p Conclusions Our results suggest that TPU + DMSO + GNP gel presents beneficial effects on the muscular healing process, inducing a reduction in the production of ROS and also the expression of pro-inflammatory molecules.

  15. The separated electric and magnetic field responses of luminescent bacteria exposed to pulsed microwave irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Catrin F., E-mail: williamscf@cardiff.ac.uk [School of Engineering, Cardiff University, Queen' s Buildings, Newport Road, Cardiff, CF24 3AA Wales (United Kingdom); School of Biosciences, Cardiff University, Main Building, Cathays Park, Cardiff, CF10 3AT Wales (United Kingdom); Geroni, Gilles M.; Pirog, Antoine; Lees, Jonathan; Porch, Adrian [School of Engineering, Cardiff University, Queen' s Buildings, Newport Road, Cardiff, CF24 3AA Wales (United Kingdom); Lloyd, David [School of Biosciences, Cardiff University, Main Building, Cathays Park, Cardiff, CF10 3AT Wales (United Kingdom)

    2016-08-29

    Electromagnetic fields (EMFs) are ubiquitous in the digital world we inhabit, with microwave and millimetre wave sources of non-ionizing radiation employed extensively in electronics and communications, e.g., in mobile phones and Wi-Fi. Indeed, the advent of 5G systems and the “internet of things” is likely to lead to massive densification of wireless networks. Whilst the thermal effects of EMFs on biological systems are well characterised, their putative non-thermal effects remain a controversial subject. Here, we use the bioluminescent marine bacterium, Vibrio fischeri, to monitor the effects of pulsed microwave electromagnetic fields, of nominal frequency 2.5 GHz, on light emission. Separated electric and magnetic field effects were investigated using a resonant microwave cavity, within which the maxima of each field are separated. For pulsed electric field exposure, the bacteria gave reproducible responses and recovery in light emission. At the lowest pulsed duty cycle (1.25%) and after short durations (100 ms) of exposure to the electric field at power levels of 4.5 W rms, we observed an initial stimulation of bioluminescence, whereas successive microwave pulses became inhibitory. Much of this behaviour is due to thermal effects, as the bacterial light output is very sensitive to the local temperature. Conversely, magnetic field exposure gave no measurable short-term responses even at the highest power levels of 32 W rms. Thus, we were able to detect, de-convolute, and evaluate independently the effects of separated electric and magnetic fields on exposure of a luminescent biological system to microwave irradiation.

  16. Selective Strong-Field Enhancement and Suppression of Ionization with Short Laser Pulses

    CERN Document Server

    Hart, Nathan A; Kolomenskii, Alexandre A; Paulus, Gerhard G; Bauer, Dieter; Schuessler, Hans A

    2015-01-01

    We experimentally demonstrate robust selective excitation and attenuation of atomic Rydberg level populations in sodium vapor (Na I) using intense laser pulses in the strong field limit ($> 10^{12} W/cm^{2}$). The coherent control of the atomic population and related ionization channels is realized for intensities above the over-the-barrier ionization intensity. A qualitative model predicts that this strong field coherent control arises through the manifestation of a Freeman resonance.

  17. Pulsed Direct Current Electric Fields Enhance Osteogenesis in Adipose-Derived Stromal Cells

    OpenAIRE

    Hammerick, Kyle E.; James, Aaron W.; Huang, Zubin; Prinz, Fritz B.; Michael T. Longaker

    2009-01-01

    Adipose-derived stromal cells (ASCs) constitute a promising source of cells for regenerative medicine applications. Previous studies of osteogenic potential in ASCs have focused on chemicals, growth factors, and mechanical stimuli. Citing the demonstrated role electric fields play in enhancing healing in bone fractures and defects, we investigated the ability of pulsed direct current electric fields to drive osteogenic differentiation in mouse ASCs. Employing 50 Hz direct current electric fie...

  18. The separated electric and magnetic field responses of luminescent bacteria exposed to pulsed microwave irradiation

    Science.gov (United States)

    Williams, Catrin F.; Geroni, Gilles M.; Pirog, Antoine; Lloyd, David; Lees, Jonathan; Porch, Adrian

    2016-08-01

    Electromagnetic fields (EMFs) are ubiquitous in the digital world we inhabit, with microwave and millimetre wave sources of non-ionizing radiation employed extensively in electronics and communications, e.g., in mobile phones and Wi-Fi. Indeed, the advent of 5G systems and the "internet of things" is likely to lead to massive densification of wireless networks. Whilst the thermal effects of EMFs on biological systems are well characterised, their putative non-thermal effects remain a controversial subject. Here, we use the bioluminescent marine bacterium, Vibrio fischeri, to monitor the effects of pulsed microwave electromagnetic fields, of nominal frequency 2.5 GHz, on light emission. Separated electric and magnetic field effects were investigated using a resonant microwave cavity, within which the maxima of each field are separated. For pulsed electric field exposure, the bacteria gave reproducible responses and recovery in light emission. At the lowest pulsed duty cycle (1.25%) and after short durations (100 ms) of exposure to the electric field at power levels of 4.5 W rms, we observed an initial stimulation of bioluminescence, whereas successive microwave pulses became inhibitory. Much of this behaviour is due to thermal effects, as the bacterial light output is very sensitive to the local temperature. Conversely, magnetic field exposure gave no measurable short-term responses even at the highest power levels of 32 W rms. Thus, we were able to detect, de-convolute, and evaluate independently the effects of separated electric and magnetic fields on exposure of a luminescent biological system to microwave irradiation.

  19. Development of a 50-T pulsed magnetic field facility by using an 1.5-MJ capacitor bank

    Science.gov (United States)

    Shin, Y. H.; Kim, Yongmin

    2015-09-01

    Because DC magnets consume a huge amount of electricity (resistive DC magnet) or liquid helium (superconducting magnet), a capacitor-bank-driven pulsed magnet is known to be a cost-effective way of generating high magnetic fields. This type of pulsed magnet is normally operated at liquid nitrogen temperature and consumes little electric power to generate over 50 tesla (T) during a short transient time of less than 50 millisecond (ms). With modern fast data acquisition systems, almost all kinds of physical quantities, such as photoluminescence, magnetization or resistance can be measured during a short magnetic field pulse. We report a recently home-built capacitor-bankdriven pulsed magnetic field facility, in which a capacitor bank of 1.5-MJ maximum stored energy is utilized to generate pulsed magnetic fields up to 50 T with transient pulse time of 22 ms.

  20. Generation of isolated attosecond extreme ultraviolet pulses employing nanoplasmonic field enhancement: optimization of coupled ellipsoids

    Energy Technology Data Exchange (ETDEWEB)

    Stebbings, S L; Suessmann, F; Yang, Y-Y; Kling, M F [Max-Planck-Institut fuer Quantenoptik, Hans-Kopfermann-Strass e 1, 85748 Garching (Germany); Scrinzi, A [Ludwig-Maximilians-Universitaet Muenchen, Theresienstrasse 37, 80333 Muenchen (Germany); Durach, M; Rusina, A; Stockman, M I, E-mail: sarah.stebbings@mpq.mpg.de, E-mail: mstockman@gsu.edu, E-mail: matthias.kling@mpq.mpg.de [Department of Physics and Astronomy, Georgia State University, 29 Peachtree Center Avenue, Atlanta, GA 30303 (United States)

    2011-07-15

    The production of extreme ultraviolet (XUV) radiation via nanoplasmonic field-enhanced high-harmonic generation (HHG) in gold nanostructures at MHz repetition rates is investigated theoretically in this paper. Analytical and numerical calculations are employed and compared in order to determine the plasmonic fields in gold ellipsoidal nanoparticles. The comparison indicates that numerical calculations can accurately predict the field enhancement and plasmonic decay, but may encounter difficulties when attempting to predict the oscillatory behavior of the plasmonic field. Numerical calculations for coupled symmetric and asymmetric ellipsoids for different carrier-envelope phases (CEPs) of the driving laser field are combined with time-dependent Schroedinger equation simulations to predict the resulting HHG spectra. The studies reveal that the plasmonic field oscillations, which are controlled by the CEP of the driving laser field, play a more important role than the nanostructure configuration in finding the optimal conditions for the generation of isolated attosecond XUV pulses via nanoplasmonic field enhancement.

  1. Generation of isolated attosecond extreme ultraviolet pulses employing nanoplasmonic field enhancement: optimization of coupled ellipsoids

    Science.gov (United States)

    Stebbings, S. L.; Süßmann, F.; Yang, Y.-Y.; Scrinzi, A.; Durach, M.; Rusina, A.; Stockman, M. I.; Kling, M. F.

    2011-07-01

    The production of extreme ultraviolet (XUV) radiation via nanoplasmonic field-enhanced high-harmonic generation (HHG) in gold nanostructures at MHz repetition rates is investigated theoretically in this paper. Analytical and numerical calculations are employed and compared in order to determine the plasmonic fields in gold ellipsoidal nanoparticles. The comparison indicates that numerical calculations can accurately predict the field enhancement and plasmonic decay, but may encounter difficulties when attempting to predict the oscillatory behavior of the plasmonic field. Numerical calculations for coupled symmetric and asymmetric ellipsoids for different carrier-envelope phases (CEPs) of the driving laser field are combined with time-dependent Schrödinger equation simulations to predict the resulting HHG spectra. The studies reveal that the plasmonic field oscillations, which are controlled by the CEP of the driving laser field, play a more important role than the nanostructure configuration in finding the optimal conditions for the generation of isolated attosecond XUV pulses via nanoplasmonic field enhancement.

  2. Effects of Pulsed Electromagnetic Field on Differentiation of HUES-17 Human Embryonic Stem Cell Line

    Directory of Open Access Journals (Sweden)

    Yi-Lin Wu

    2014-08-01

    Full Text Available Electromagnetic fields are considered to potentially affect embryonic development, but the mechanism is still unknown. In this study, human embryonic stem cell (hESC line HUES-17 was applied to explore the mechanism of exposure on embryonic development to pulsed electromagnetic field (PEMF for 400 pulses at different electric field intensities and the differentiation of HUES-17 cells was observed after PEMF exposure. The expression of alkaline phosphatase (AP, stage-specific embryonic antigen-3 (SSEA-3, SSEA-4 and the mRNA level and protein level of Oct4, Sox2 and Nanog in HUES-17 cells remained unchanged after PEMF exposure at the electric field intensities of 50, 100, 200 or 400 kV/m. Four hundred pulses PEMF exposure at the electric field intensities of 50, 100, 200 or 400 kV/m did not affect the differentiation of HUES-17 cells. The reason why electromagnetic fields affect embryonic development may be due to other mechanisms rather than affecting the differentiation of embryonic stem cells.

  3. High-Order Temporal Corrected Fields of Ultra-Short Laser Pulses and Laser-Driven Acceleration

    Institute of Scientific and Technical Information of China (English)

    XIE Yong-Jie; HUO Yu-Kun; KONG Qing; WANG Ping-Xiao; CHEN Zhao; LIU Jing-Ru

    2006-01-01

    @@ Up to third-order temporal correction in terms of a small dimensionless temporal parameter ε = 1/(ω0t0) (ω0 =ck0 the central oscillatory frequency, t0 the pulse duration of half period), the field expressions of ultra-short focused laser pulses are explicitly presented. To evaluate the correction efficacy, electric amplitudes of zeroth-order and higher-order corrected fields are compared for different pulse durations. Furthermore, electron interaction with ultra-short laser pulses is simulated using both the zeroth-order and higher-order corrected field equations.

  4. Optical field ionization of atoms and ions using ultrashort laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Fittinghoff, D.N.

    1993-12-01

    This dissertation research is an investigation of the strong optical field ionization of atoms and ions by 120-fs, 614-run laser pulses and 130-fs, 800-nm laser pulses. The experiments have shown ionization that is enhanced above the predictions of sequential tunneling models for He{sup +2}, Ne{sup +2} and Ar{sup +2}. The ion yields for He{sup +l}, Ne{sup +l} and Ar{sup +l} agree well with the theoretical predictions of optical tunneling models. Investigation of the polarization dependence of the ionization indicates that the enhancements are consistent with a nonsequential ionization mechanism in which the linearly polarized field drives the electron wavefunction back toward the ion core and causes double ionization through inelastic e-2e scattering. These investigations have initiated a number of other studies by other groups and are of current scientific interest in the fields of high-irradiance laser-matter interactions and production of high-density plasmas. This work involved: (1) Understanding the characteristic nature of the ion yields produced by tunneling ionization through investigation of analytic solutions for tunneling at optical frequencies. (2) Extensive characterization of the pulses produced by 614-nm and 800-ran ultrashort pulse lasers. Absolute calibration of the irradiance scale produced shows the practicality of the inverse problem--measuring peak laser irradiance using ion yields. (3) Measuring the ion yields for three noble gases using linear, circular and elliptical polarizations of laser pulses at 614-nm and 800-nm. The measurements are some of the first measurements for pulse widths as low as 120-fs.

  5. Amp\\`ere-Class Pulsed Field Emission from Carbon-Nanotube Cathodes in a Radiofrequency Resonator

    CERN Document Server

    Mihalcea, D; Hartzell, J; Panuganti, H; Boucher, S M; Murokh, A; Piot, P; Thangaraj, J C T

    2015-01-01

    Pulsed field emission from cold carbon-nanotube cathodes placed in a radiofrequency resonant cavity was observed. The cathodes were located on the backplate of a conventional $1+\\frac{1}{2}$-cell resonant cavity operating at 1.3-GHz and resulted in the production of bunch train with maximum average current close to 0.7 Amp\\`ere. The measured Fowler-Nordheim characteristic, transverse emittance, and pulse duration are presented and, when possible, compared to numerical simulations. The implications of our results to high-average-current electron sources are briefly discussed.

  6. Trapped fields up to 2 T in a 12 mm square stack of commercial superconducting tape using pulsed field magnetization

    Science.gov (United States)

    Patel, A.; Hopkins, S. C.; Glowacki, B. A.

    2013-03-01

    The ability of superconductors to sustain persistent currents has been well exploited with (RE)BCO superconducting bulks, which can be magnetized to form a compact source of high magnetic field. However, thin films can also sustain persistent currents, which can be utilized by stacking them in layers to create a type of composite bulk. Such a stack is capable of trapping higher fields than a bulk, as reported in this paper. 12 mm wide, 55 μm thick commercial (RE)BCO tape from Superpower Inc was cut into 12 mm by 12 mm squares, stacked together and magnetized at temperatures between 10 and 77.4 K using a sequence of pulsed magnetic fields. The results are compared to a commercial 14 mm diameter YBCO bulk, showing that the stack of tapes outperformed the bulk at temperatures below approximately 60 K. Particularly high trapped fields were achieved below 50 K, with a maximum of 2.0 T at 10 K measured 0.8 mm from the stack surface. The maximum trapped field possible for a stack of tapes increases significantly with decreasing temperature down to 10 K, rather than saturating at a higher temperature as in the case of a bulk, due to superior thermal stability. The Jc, thermal and mechanical properties of commercial (RE)BCO tapes give them great potential for use as trapped field magnets activated by pulsed magnetic fields.

  7. Enhanced trapped field performance of bulk high-temperature superconductors using split coil, pulsed field magnetization with an iron yoke

    Science.gov (United States)

    Ainslie, M. D.; Fujishiro, H.; Mochizuki, H.; Takahashi, K.; Shi, Y.-H.; Namburi, D. K.; Zou, J.; Zhou, D.; Dennis, A. R.; Cardwell, D. A.

    2016-07-01

    Investigating and predicting the magnetization of bulk superconducting materials and developing practical magnetizing techniques is crucial to using them as trapped field magnets in engineering applications. The pulsed field magnetization (PFM) technique is considered to be a compact, mobile and relative inexpensive way to magnetize bulk samples, requiring shorter magnetization times (on the order of milliseconds) and a smaller and less complicated magnetization fixture; however, the trapped field produced by PFM is generally much smaller than that of slower zero field cooling or field cooling techniques, particularly at lower operating temperatures. In this paper, the PFM of two, standard Ag-containing Gd-Ba-Cu-O samples is carried out using two types of magnetizing coils: (1) a solenoid coil, and (2) a split coil, both of which make use of an iron yoke to enhance the trapped magnetic field. It is shown that a significantly higher trapped field can be achieved using a split coil with an iron yoke, and in order to explain these how this arrangement works in detail, numerical simulations using a 2D axisymmetric finite element method based on the H -formulation are carried to qualitatively reproduce and analyze the magnetization process from both electromagnetic and thermal points of view. It is observed that after the pulse peak significantly less flux exits the bulk when the iron core is present, resulting in a higher peak trapped field, as well as more overall trapped flux, after the magnetization process is complete. The results have important implications for practical applications of bulk superconductors as such a split coil arrangement with an iron yoke could be incorporated into the design of a portable, high magnetic field source/magnet to enhance the available magnetic field or in an axial gap-type bulk superconducting electric machine, where iron can be incorporated into the stator windings to (1) improve the trapped field from the magnetization process

  8. Mid-infrared strong-field ionization of clusters using two-cycle pulses

    CERN Document Server

    Schütte, Bernd; Austin, Dane R; Brahms, Christian; Strüber, Christian; Witting, Tobias; Tisch, John W G; Marangos, Jonathan P

    2016-01-01

    We study mid-infrared strong-field ionization of rare-gas clusters ($10^3$ to $10^5$ atoms) in the impulsive limit using 12 fs laser pulses. The emission of fast electrons with kinetic energies exceeding 3 keV is observed at 1.8 $\\mu$m and an intensity of $1\\times 10^{15}$ W/cm$^2$, whereas only electrons below 500 eV are observed at 800 nm using a similar intensity and pulse duration. Fast electrons are preferentially emitted along the laser polarization direction, indicating that they are driven out from the cluster by the laser field via direct and rescattering processes within a few femtoseconds. In contrast to previous near-infrared strong-field ionization experiments in clusters using 200-1000 fs laser pulses, the yield of fast electrons decreases with increasing pulse duration. Scaling to longer wavelengths is expected to result in a highly directional current of hot electrons on a few-femtosecond timescale.

  9. Measurement of dynamic magnetization induced by a pulsed field: Proposal for a new rock magnetism method

    Science.gov (United States)

    Kodama, Kazuto

    2015-02-01

    This study proposes a new method for measuring transient magnetization of natural samples induced by a pulsed field with duration of 11 ms using a pulse magnetizer. An experimental system was constructed, consisting of a pair of differential sensing coils connected with a high-speed digital oscilloscope for data acquisition. The data were transferred to a computer to obtain an initial magnetization curve and a descending branch of a hysteresis loop in a rapidly changing positive field. This system was tested with synthetic samples (permalloy ribbon, aluminum plate, and nickel powder) as well as two volcanic rock samples. Results from the synthetic samples showed considerable differences from those measured by a quasi-static method using a vibrating sample magnetometer (VSM). These differences were principally due to the time-dependent magnetic properties or to electromagnetic effects, such as magnetic viscosity, eddy current loss, or magnetic relaxation. Results from the natural samples showed that the transient magnetization-field curves were largely comparable to the corresponding portions of the hysteresis loops. However, the relative magnetization (scaled to the saturation magnetization) at the end of a pulse was greater than that measured by a VSM. This discrepancy, together with the occurrence of rapid exponential decay after a pulse, indicates magnetic relaxations that could be interpreted in terms of domain wall displacement. These results suggest that with further developments, the proposed technique can become a useful tool for characterizing magnetic particles contained in a variety of natural materials.

  10. Spectrum of fast electrons in a dense gas in the presence of a nonuniform pulsed field

    Science.gov (United States)

    Tkachev, A. N.; Yakovlenko, S. I.

    2007-01-01

    The problems of gas preionization in discharges related to laser physics are considered. The propagation of fast electrons injected from the cathode in the presence of a nonuniform nonstationary field and the motion of multiplying electrons at the edge of the avalanche in the presence of a nonuniform nonstationary field are simulated. The effect of the voltage pulse steepness and the field nonuniformity on the mean propagation velocity of fast electrons and their energy distribution is demonstrated. At certain combinations of the voltage pulse rise time and amplitude and at a certain time interval, the center of gravity of the electron cloud can move in the opposite direction relative to the direction of force acting upon electrons. It is also demonstrated that the number of hard particles (and, hence, the hard component of the x-ray bremsstrahlung) increases with both an increase in the voltage amplitude and a decrease in the pulse rise time. For nonoptimal conditions of the picosecond voltage pulse, an assumption is formulated: an electron beam in gas is formed due to the electrons at the edge of the avalanche rather than the background multiplication wave approaching the anode.

  11. Measurement of dynamic magnetization induced by a pulsed field: Proposal for a new rock magnetism method

    Directory of Open Access Journals (Sweden)

    Kazuto eKodama

    2015-02-01

    Full Text Available This study proposes a new method for measuring transient magnetization of natural samples induced by a pulsed field with duration of 11 ms using a pulse magnetizer. An experimental system was constructed, consisting of a pair of differential sensing coils connected with a high-speed digital oscilloscope for data acquisition. The data were transferred to a computer to obtain an initial magnetization curve and a descending branch of a hysteresis loop in a rapidly changing positive field. This system was tested with synthetic samples (permalloy ribbon, aluminum plate, and nickel powder as well as two volcanic rock samples. Results from the synthetic samples showed considerable differences from those measured by a quasi-static method using a vibrating sample magnetometer (VSM. These differences were principally due to the time-dependent magnetic properties or to electromagnetic effects, such as magnetic viscosity, eddy current loss, or magnetic relaxation. Results from the natural samples showed that the transient magnetization–field curves were largely comparable to the corresponding portions of the hysteresis loops. However, the relative magnetization (scaled to the saturation magnetization at the end of a pulse was greater than that measured by a VSM. This discrepancy, together with the occurrence of rapid exponential decay after a pulse, indicates magnetic relaxations that could be interpreted in terms of domain wall displacement. These results suggest that with further developments, the proposed technique can become a useful tool for characterizing magnetic particles contained in a variety of natural materials.

  12. Enhanced anthocyanin extraction from red cabbage using pulsed electric field processing.

    Science.gov (United States)

    Gachovska, Tanya; Cassada, David; Subbiah, Jeyamkondan; Hanna, Milford; Thippareddi, Harshavardhan; Snow, Daniel

    2010-08-01

    This study was conducted to evaluate the effect of pulsed electric field (PEF) treatment on anthocyanin extraction from red cabbage using water as a solvent. Mashed cabbage was placed in a batch treatment chamber and subjected to PEF (2.5 kV/cm electric field strength; 15 micros pulse width and 50 pulses, specific energy 15.63 J/g). Extracted anthocyanin concentrations (16 to 889 microg/mL) were determined using HPLC. Heat and light stabilities of the control and PEF-treated samples, having approximately the same initial concentrations, were studied. PEF treatments enhanced total anthocyanin extraction in water from red cabbage by 2.15 times with a higher proportion of nonacylated forms than the control (P light stabilities of the PEF-treated samples and control samples were not significantly different (P > 0.05). Practical Application: An innovative pretreatment technology, pulsed electric field processing, enhanced total anthocyanin extraction in water from red cabbage by 2.15 times. Manufacturers of natural colors can use this technology to extract anthocyanins from red cabbage efficiently.

  13. Nonmonotonous variation of DNA angular separation during asymmetric pulsed field electrophoresis.

    Science.gov (United States)

    Nazemifard, Neda; Bhattacharjee, Subir; Masliyah, Jacob H; Harrison, D Jed

    2013-09-01

    Asymmetric pulsed field electrophoresis within crystalline arrays is used to generate angular separation of DNA molecules. Four regimes of the frequency response are observed, a low frequency rise in angular separation, a plateau, a subsequent decline, and a second plateau at higher frequencies. It is shown that the frequency response for different sized DNA is governed by the relation between pulse time and the reorientation time of DNA molecules. The decline in angular separation at higher frequencies has not previously been analyzed. Real-time videos of single DNA molecules migrating under high frequency-pulsed electric field show the molecules no longer follow the head to tail switching, ratchet mechanism seen at lower frequencies. Once the pulse period is shorter than the reorientation time, the migration mechanism changes significantly. The molecule reptates along the average direction of the two electric fields, which reduces the angular separation. A freely jointed chain model of DNA is developed where the porous structure is represented with a hexagonal array of obstacles. The model qualitatively predicts the variation of DNA angular separation with respect to frequency.

  14. Near and intermediate fields of an ultrashort pulse transmitted through Young’s double-slit experiment

    NARCIS (Netherlands)

    Nugrowati, A.M.; Pereira, S.F.; Van de Nes, A.S.

    2008-01-01

    We present a systematic study of the transmitted field of an ultrashort pulse through Young’s double slit. We show how the spatial-temporal distribution of the field in the near and intermediate zone is affected by the input polarization state of the pulse. The analysis has been separated to study t

  15. Near and intermediate fields of an ultrashort pulse transmitted through Young’s double-slit experiment

    NARCIS (Netherlands)

    Nugrowati, A.M.; Pereira, S.F.; Van de Nes, A.S.

    2008-01-01

    We present a systematic study of the transmitted field of an ultrashort pulse through Young’s double slit. We show how the spatial-temporal distribution of the field in the near and intermediate zone is affected by the input polarization state of the pulse. The analysis has been separated to study

  16. The influence of size and shape of microorganism on pulsed electric field inactivation.

    Science.gov (United States)

    El-Hag, Ayman H; Jayaram, Shesha H; Gonzalez, Oscar Rodriguez; Griffiths, M W

    2011-09-01

    In this paper the effect of microorganism size and shape on the killing efficiency of pulsed electric field (PEF) is investigated both experimentally and using a transient finite element program. The effect of cell size, membrane thickness, cell shape (spherical, elliptical, and cylindrical) on the calculated transmembrane voltage is studied. It has been found that both the cell size and cell membrane thickness have significant effect on the induced field across the cell membrane. The findings of the simulation results have been evaluated by comparing the trends with some experimental results. Five different types of microorganisms that have different shapes and dimensions have been inoculated with water at a conductivity level of 100 μS/cm and have been treated with the application of a pulsed electric field of 70 kV/cm. Significant difference in bacteria reduction was noticed between the treated cells which could be attributed to the cell size and shape.

  17. Fast simulation of non-linear pulsed ultrasound fields using an angular spectrum approach

    DEFF Research Database (Denmark)

    Du, Yigang; Jensen, Jørgen Arendt

    2013-01-01

    . The accuracy of the nonlinear ASA is compared to the non-linear simulation program – Abersim, which is a numerical solution to the Burgers equation based on the OSM. Simulations are performed for a linear array transducer with 64 active elements, focus at 40 mm, and excitation by a 2-cycle sine wave......A fast non-linear pulsed ultrasound field simulation is presented. It is implemented based on an angular spectrum approach (ASA), which analytically solves the non-linear wave equation. The ASA solution to the Westervelt equation is derived in detail. The calculation speed is significantly...... increased compared to a numerical solution using an operator splitting method (OSM). The ASA has been modified and extended to pulsed non-linear ultrasound fields in combination with Field II, where any array transducer with arbitrary geometry, excitation, focusing and apodization can be simulated...

  18. Neutron investigations of magnetic properties of crystal substances with use of a pulsed magnetic field

    CERN Document Server

    Nitts, V V

    2001-01-01

    Bases for neutron researches of magnetic properties of crystal substances with use of a pulsed magnetic field and analysis of possible application of various neutron sources in this area are submitted. The review of the most interesting physical results is presented. Main investigations on pulsed reactors of JINR are researches on kinetics of the first order reorientational phase transitions induced in single crystals, and also measurements of antiferromagnetic ordering induced by an external magnetic field. Magnetic phase transitions, induced by a field up to 160 kOe in several magnetic ordering substances, were studied in KEK (Japan). Experiment on observation of spin-flop transition in MnF sub 2 was carried out on TRIGA-reactor in a mode of single flashes of power

  19. Composite NDE using full-field pulse-echo ultrasonic propagation imaging system

    Science.gov (United States)

    Hong, Seung-Chan; Lee, Jung-Ryul; Park, Jongwoon

    2016-04-01

    In this paper, a novel ultrasonic propagation imaging system, called a full-field pulse-echo ultrasonic propagation imaging (FF PE UPI) system is presented. The coincided laser beams for ultrasonic sensing and generation are scanned and pulse-echo mode laser ultrasounds are captured. This procedure makes it possible to generate full-field ultrasound in through-the-thickness direction as large as the scan area. The system nondestructively inspected targets with two-axis translation stages. Various structural inspection results in the form of full-field ultrasonic wave propagation videos are introduced, which are an aluminum honeycomb sandwich, ailerons and carbon fiber reinforced plastic (CFRP) honeycomb sandwich structures including various defects.

  20. Determination of relevant parameters for the use of electronic dosemeters in pulsed fields of ionising radiation.

    Science.gov (United States)

    Zutz, H; Hupe, O; Ambrosi, P; Klammer, J

    2012-09-01

    Active electronic dosemeters using counting techniques are used for radioprotection purposes in pulsed radiation fields in X-ray diagnostics or therapy. The disadvantage of the limited maximum measurable dose rate becomes significant in these radiation fields and leads to some negative effects. In this study, a set of relevant parameters for a dosemeter is described, which can be used to decide whether it is applicable in a given radiation field or not. The determination of these relevant parameters-maximum measurable dose rate in the radiation pulse, dead time of the dosemeter, indication per counting event and measurement cycle time-is specified. The results of the first measurements on the determination of these parameters for an electronic personal dosemeter of the type Thermo Fisher Scientific EPD Mk2 are shown.